WO2007025926A1 - Method for controlling a brake system of a motor vehicle - Google Patents

Method for controlling a brake system of a motor vehicle Download PDF

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Publication number
WO2007025926A1
WO2007025926A1 PCT/EP2006/065607 EP2006065607W WO2007025926A1 WO 2007025926 A1 WO2007025926 A1 WO 2007025926A1 EP 2006065607 W EP2006065607 W EP 2006065607W WO 2007025926 A1 WO2007025926 A1 WO 2007025926A1
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WO
WIPO (PCT)
Prior art keywords
generator
vehicle
vehicle axle
axle
braking
Prior art date
Application number
PCT/EP2006/065607
Other languages
German (de)
French (fr)
Inventor
Gregor Schmitt
Markus Jäger
Original Assignee
Continental Teves Ag & Co. Ohg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Continental Teves Ag & Co. Ohg filed Critical Continental Teves Ag & Co. Ohg
Publication of WO2007025926A1 publication Critical patent/WO2007025926A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K23/00—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for
    • B60K23/08—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for changing number of driven wheels, for switching from driving one axle to driving two or more axles
    • B60K23/0808—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for changing number of driven wheels, for switching from driving one axle to driving two or more axles for varying torque distribution between driven axles, e.g. by transfer clutch
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00—Control systems specially adapted for hybrid vehicles
    • B60W20/10—Controlling the power contribution of each of the prime movers to meet required power demand
    • B60W20/13—Controlling the power contribution of each of the prime movers to meet required power demand in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T1/00—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles
    • B60T1/02—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels
    • B60T1/10—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels by utilising wheel movement for accumulating energy, e.g. driving air compressors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
    • B60T8/1766—Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
    • B60T8/1769—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS specially adapted for vehicles having more than one driven axle, e.g. four-wheel drive vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/321—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration deceleration
    • B60T8/322—Systems specially adapted for vehicles driven by more than one axle, e.g. Four Wheel-Drive vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/08—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of electric propulsion units, e.g. motors or generators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/119—Conjoint control of vehicle sub-units of different type or different function including control of all-wheel-driveline means, e.g. transfer gears or clutches for dividing torque between front and rear axle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/18—Conjoint control of vehicle sub-units of different type or different function including control of braking systems
    • B60W10/184—Conjoint control of vehicle sub-units of different type or different function including control of braking systems with wheel brakes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/18—Propelling the vehicle
    • B60W30/18009—Propelling the vehicle related to particular drive situations
    • B60W30/18109—Braking
    • B60W30/18127—Regenerative braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2270/00—Further aspects of brake control systems not otherwise provided for
    • B60T2270/60—Regenerative braking
    • B60T2270/608—Electronic brake distribution (EBV/EBD) features related thereto
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00—Control systems specially adapted for hybrid vehicles

Definitions

  • the invention relates to a method for controlling a brake system of a motor vehicle, in particular for controlling a regenerative braking system of a motor vehicle with electronically engageable four-wheel clutch, comprising a number of hydraulic, electronically controllable, each associated with a vehicle axle friction brakes and a generator, the power flow side with a first Vehicle axle is permanently connected to the other and second vehicle axle via an electronically controllable four-wheel clutch. It further relates to a regenerative braking system for a motor vehicle.
  • regenerative braking systems In vehicles, so-called regenerative braking systems can be used, in which at least part of the energy applied during braking can be stored in the vehicle and later reused for driving the vehicle. As a result, the overall energy consumption of the vehicle can be reduced, the efficiency increased and the operation can be made more economical.
  • Motor vehicles with a regenerative braking system generally have different types of brakes, also referred to as brake actuators, namely, on the one hand, hydraulically actuated friction brakes and, on the other hand, an electrically regenerative brake with respect to varying system requirements.
  • the brake pressure for the friction brakes is applied in such systems at least partially as in conventional friction brakes via a brake pressure generating means and the brake pedal movement.
  • the electric regenerative brake is generally designed as an electrical generator, via which at least part of the total braking power is applied.
  • the electrical energy obtained is fed or fed back into a storage medium such as an on-board battery and can be reused for driving the motor vehicle via a suitable drive.
  • the braking force requirement is distributed in a suitable form to the individual brake actuators.
  • the distribution of braking energy in shares of the friction brakes and shares of the electric generator is usually dependent on the desired braking torque, the state of charge of the battery and in particular the operating range and other special properties of the generator. In this case, preference is usually given to extensive use of the electro-regenerative brakes or generator brake, the braking power of which should be used as extensively as possible in order to be able to recover a particularly high level of braking energy. Only when the braking torque of the generator brake is no longer sufficient, the system of the friction brakes is switched on. However, the generator braking torque is generally only implemented on a vehicle axle, in particular on the front axle.
  • ABS anti-lock braking system
  • the invention is therefore based on the object to provide a method for controlling the brake system of a motor vehicle of the above type, with a particularly favorable braking behavior when using the generator brake or electric regenerative brake can be achieved.
  • a particularly suitable for carrying out the method braking system for a motor vehicle of the type mentioned will be specified.
  • this object is achieved according to the invention by determining, according to the specification of a situation-dependent average rated braking torque for the generator, the four-wheel clutch is applied with a predetermined control value.
  • the invention is based on the consideration that especially in a motor vehicle with shiftable four-wheel drive, a particularly favorable braking behavior of an electric regenerative brake can be achieved by the situationally provided generator braking torque is suitably distributed to both vehicle axles, ie in particular on the front and rear axles.
  • the observance of a braking force ratio which in any case is considered to be particularly favorable or ideal, may be sought when the vehicle axles are subjected to a generator braking torque.
  • the generator should be suitably connected to the vehicle axles on the power flow side.
  • the four-wheel clutch should be acted upon with a suitably selected control value so that there is a special favorable Bremsmomentenver- distribution of the generator on the vehicle axles.
  • the manipulated variable for the four-wheel clutch can be specified such that the generator in a fixed torque ratio, preferably according to a predetermined ideal Bremskraftverhaltnis, especially in a moment ratio of about 70:30, acts on the vehicle axles.
  • the manipulated variable can advantageously also be determined depending on the situation and / or depending on the delay and suitably specified for the four-wheel clutch.
  • the four-wheel drive can be controlled advantageously delay dependent according to an on the basis of other conditions, based on empirical knowledge or situation-dependent determined ideal braking force ratio.
  • the full road friction coefficient can also be utilized in regenerative braking, with it also being possible to implement a maximum of generator power.
  • part of the total braking torque must be covered by an additional friction brake component.
  • the control value for the four-wheel drive is set such that the generator braking torque with a situation-dependent determined from a predetermined or ideal braking force braking torque on the first, permanently connected to the generator vehicle axle, in particular the front axle acts.
  • the four-wheel drive is preferably controlled such that the generator with the remaining available generator braking torque acts on the second vehicle axle, wherein the required in view of the total Sollbrems- and ideal braking force distribution additionally required for the second vehicle axle or rear axle braking torque on the rear axle associated friction brakes is applied.
  • the friction brakes associated with the second vehicle axle are advantageously switched on suitably so that, overall, a braking torque determined depending on the situation from a predetermined braking force ratio acts on the second vehicle axle.
  • control value for the four-wheel clutch is output only when the total requested brake moment exceeds a predetermined limit.
  • the activation of the all-wheel clutch above the predetermined limit value is advantageously carried out such that when the limit value is reached, first the clutch ratio is controlled as a function of the requested braking torque, that the generator torque applied to the first vehicle axle or front axle remains constant and only at the second vehicle axle or rear axle is constructed further generator torque until the torque ratio corresponds to the vehicle axles of the ideal brake force distribution.
  • the stated object is achieved by the electronically controllable four-wheel clutch, which connects the second vehicle axle frictional side operating point-dependent with the generator, is acted upon by a brake control unit with a control value.
  • the brake control unit is thus designed such that it can supply the four-wheel clutch, a control value, so that the activation of the all-wheel drive is in the context of the brake concept ever made possible.
  • the advantages achieved by the invention are in particular that by applying the four-wheel clutch with a control value as a function of the braking requirements, the electric regenerative brake is used in a particularly favorable manner.
  • the four-wheel clutch is closed during braking, which take place wholly or partly via the regenerative brake, to a certain extent such that the braking torque of the regenerative braking distributed in a certain, considered particularly favorable ratio on both vehicle axles.
  • Fig. 1 shows schematically a brake system of a motor vehicle
  • Fig. 2 is a diagram for the distribution of torque components.
  • the brake system 1 according to FIG. 1 is associated with a motor vehicle and comprises in the manner of a hybrid system a hydraulic subsystem and an electrically regenerative subsystem.
  • the hydraulic portion of the brake system 1 comprises a number of hydraulic, electronically controllable friction brakes 2, 4, which are each arranged on a wheel 6.
  • the friction brakes 2 are assigned to the front axle or first vehicle axle 8 of the motor vehicle, whereas the friction brakes 4 are assigned to the rear axle or second vehicle axle 10.
  • the friction brakes 2, 4 are acted upon by a not shown near brake hydraulic system of conventional design with a Hyraulikmannmaschine and can thus be activated.
  • a central brake control unit 14 which can selectively control hydraulic valves of the respective friction brakes 2, 4, for example via the control lines, in order to allow a controlled pressure build-up on the respective friction brake 2, 4 , By the brake control unit 14 so that a wheel-individual control of the friction brakes 2, 4 allows. If required or as a function of the situation, the brake control unit 14 can act in particular as ABS or ESP control.
  • the brake system 1 also includes an electric regenerative portion via which the Braking as far as possible recovery of the energy consumed is to be achieved.
  • the electric regenerative subsystem of the brake system 1 comprises a generator 20, which is permanently connected via a shaft 22 to a differential gear 24 and via this to the first vehicle axle 8.
  • the generator 20 In the drive mode, the generator 20 thereby drives the front axle or first vehicle axle 8 of the motor vehicle, whereas in the braking mode the generator 20 in turn is driven by the first vehicle axle 8 and thereby generates electrical energy.
  • the generator 20 is connected in a manner not shown with a suitably selected battery unit.
  • the generator 20 In order to enable a suitable integration of the electric regenerative subsystem in the braking operation in such braking phases and in particular the distribution of the torque components, which are applied to generate the total braking torque of the hydraulic portion and the electric regenerative portion of the brake system 1, adapted to predetermined or desired torque distributions to hold, the generator 20, as indicated by the arrow 25, also driven by the brake control unit 14.
  • the brake control unit 14 By the output of suitable control values to the hydraulic friction brakes 2, 4 on the one hand and to the generator 20 on the other hand, the brake control unit 14 thus contribute to maintaining predetermined torque distributions.
  • the motor vehicle is provided in the exemplary embodiment with a switchable four-wheel drive or 4x4 drive.
  • the generator 20 is on the power flow side via a shaft 26, in which an electronically controllable four-wheel clutch 28 is connected, and via a differential 30 with the rear axle or second vehicle axle 10 of the motor vehicle. prevented.
  • the four-wheel clutch 28 in a manner not shown acted upon with control values from an on-board control system in the driver's choice depending or predetermined by the on-board electronics in the drive mode opening or closing the Four-wheel clutch 28 effect.
  • the braking system 1 is designed in a specific way to integrate the switchable four-wheel drive of the motor vehicle in the braking process and in particular in the moment divisions between hydraulic components and electric regenerative shares on the one hand and between the vehicle axles 8, 10 on the other hand particularly favorable.
  • the four-wheel clutch 28 can also be controlled by the brake control unit 14 and acted upon by a control value. In this way, it can be ensured that the four-wheel drive clutch 28 can be closed to a certain extent during braking, which takes place wholly or partly via the regenerative brake, so that the braking torque of the regenerative braking or the generator 20 is applied to the vehicle axles 8 in a desired ratio , 10 distributed.
  • the brake system 1 can be designed to largely comply with a pre-set or ideal brake force distribution between the two vehicle axles 8, 10 in order to ensure particularly high vehicle stability during braking and also compliance with particularly high driver comfort requirements. chen.
  • the brake system 1 could, in particular by appropriate design of the brake control unit 14, be designed such that the regenerative braking torque in the electric regenerative braking in a fixed ratio to the vehicle axles 8, 10, for example in a ratio of 70:30 for front to rear axle is split, wherein the four-wheel clutch 28 would be acted upon by a corresponding control value from the brake control unit 14.
  • the brake system 1 is designed such that the control value for the four-wheel clutch 28 is output by the brake control unit 14 in a situation-dependent or delay-dependent manner in such a way that braking results which are perceived as particularly favorable can be achieved.
  • the diagrammatic representation in FIG. 2 is used to explain the criteria according to which the manipulated variable for the four-wheel drive 28 is output.
  • the diagram according to FIG. 2 shows as a function of the parameter total braking torque or driver command M plotted on the X-axis on the Y-axis. Axis removed individual moment contributions or shares.
  • the straight line 40 likewise represents the driver's wish and thus represents in each case the desired braking torque to be applied overall by the sum of the electric regenerative braking contribution and the hydraulic braking contribution to all four wheels 6.
  • the straight lines 42 and 44 which represent the desired torque components on the front axle (straight line 42) or on the rear axle (straight line 44) for a braking force distribution recognized as ideal.
  • the distribution of the total braking torque represented by the straight lines 42, 44 to a front axle portion and a rear axle portion corresponds to a so-called ideal Brake force ratio, which has been determined for example on the basis of stability considerations, safety criteria and the like. It is basically desirable for the brake system 1 to approximate the torque distribution between the front axle and the rear axle to the values represented by the straight lines 42, 44.
  • the brake system 1 is designed to output certain torque components to the individual brakes, the control value output to the four-wheel clutch 28 being respectively selected accordingly.
  • the torque distribution is carried out depending on the size of the total applied braking torque M according to slightly different criteria, as will be explained in more detail below.
  • the parameter range of the braking torque M to be applied overall is divided into a plurality of phases or intervals Ii to I 5 , in which the respective torque input takes place somewhat differently in each case.
  • the braking torque to be applied overall is smaller than a predetermined limit value represented by the dashed straight line 46.
  • a predetermined limit value represented by the dashed straight line 46.
  • this is expressed by the fact that in the region of the first interval Ii the line 50 representing the proportion of the regenerative braking torque on the first vehicle axle 8 is characterized by the driver's request or the total braking torque to be applied.
  • the mode of operation according to interval Ii for comparatively small braking torques to be applied overall is particularly advantageous in order to avoid an excessive increase in the numbers of load cycles of the all-wheel drive clutch 28.
  • the torque distribution takes place according to the second phase or the interval I 2 .
  • a targeted activation of the four-wheel drive clutch 28 can now be used successively to build up additional electrical-regenerative braking torque also on the rear axle or second vehicle axle 8.
  • the electric-regenerative braking torque output to the front axle or first vehicle axle 8 is therefore kept constant even with a further increase in the driver's request; Accordingly, in the interval I 2, the line 50 runs horizontally.
  • the four-wheel clutch 28 is acted upon by a control value that corresponds to the vehicle axles 8, 10 each further given electrical-regenerative torque in each case the proportion of the ideal brake force distribution.
  • the full road friction coefficient can also be exploited during regenerative braking and at the same time implement maximum generator power.
  • the fourth phase or the interval I 4 thus begins at the point at which the sum of the torque components according to line 50 and according to line 52 is equal to the value given by the dashed line 54. From this value for the driver's request, the engagement of the friction brakes is required in addition to the electric regenerative brake.
  • the control value for the four-wheel clutch 28 is set such that the output to the first vehicle axle 8 or the front axle electric regenerative braking torque still corresponds to the transmitted from the ideal braking force distribution for the front axle torque component; Accordingly, in the interval I 4, the line 50 and the line 42 also coincide.
  • the four-wheel drive clutch 28 is controlled in such a way that the remaining braking torque available from the electric regenerative brake is forwarded to the rear axle or second vehicle axle 10.
  • the friction brakes 4 on the rear axle 10 are increasingly switched in such that the total braking torque acting on the second vehicle axle 10, composed of electrically regenerative braking torque and hydraulic braking torque, corresponds to the proportion according to the ideal braking force ratio.
  • the hydraulic component of the braking torque on the second vehicle axle 10 is represented by the line 56 in the diagram according to FIG. 2.
  • the four-wheel drive 28 is thus just opened so that the resulting, as ideal as possible brake force distribution results from the resulting shift of the generator braking torque from the rear to the front axle and the structure of friction brake on the rear axle.
  • the point is eventually reached at which the available generator braking torque is no longer sufficient to apply the proportion of the front axle according to the ideal brake force distribution.
  • this corresponds to the point at which the line 42 intersects the line 54 representative of the maximum applicable generator braking torque.
  • the fifth phase or interval I 5 begins.
  • the entire applicable generator braking torque is held on the front axle; accordingly, line 50 runs horizontally in this area.
  • the desired braking torque on the rear axle is applied exclusively by the friction brakes 4; Accordingly, in the interval I 5, the line 56 is congruent with the straight line 44.
  • the additionally required Braking torque at the front axle is applied in this case by further control of the friction brakes 2, the moment proportion is represented in the diagram by the line 58.
  • the electric regenerative brake is used particularly effectively with high stability and operational safety.
  • the four-wheel clutch 28 is opened immediately and no more generator torque required to allow a wheel-individual control.

Abstract

In the control of a brake system (1) of a motor vehicle having a switchable all-wheel drive system (28) which comprises a number of hydraulic, electronically controllable friction brakes (2, 4) which are assigned in each case to one vehicle axle (8, 10) and a generator (20) which is connected permanently on the force-flow side to a first vehicle axle (8) and to the other, second vehicle axle (10) via an electronically controllable all-wheel drive clutch (28), a particularly high degree of regenerative electricity efficiency and high operational stability and reliability are to be ensured. For this purpose, according to the invention, the all-wheel drive clutch (28) is loaded with a predefined actuating value according to the stipulation of a setpoint braking moment which is determined as a function of the situation for the generator (20), in order to divide the braking moment between the front axle and the rear axle in a desired ratio, for example according to a brake force distribution which is recognized as ideal.

Description

Verfahren zur Steuerung eines Bremssystems eines KraftfahrzeugsMethod for controlling a brake system of a motor vehicle
Die Erfindung betrifft ein Verfahren zur Steuerung eines Bremssystems eines Kraftfahrzeugs, insbesondere für die Steuerung eines regenerativen Bremssystems eines Kraftfahrzeugs mit elektronisch zuschaltbarer Allradkupplung, das eine Anzahl von hydraulischen, elektronisch steuerbaren, jeweils einer Fahrzeugachse zugeordneten Reibbremsen und einen Generator umfasst, der kraftflussseitig mit einer ersten Fahrzeugachse permanent und mit der anderen, zweiten Fahrzeugachse über eine elektronisch ansteuerbare Allradkupplung verbunden ist. Sie betrifft weiterhin ein regeneratives Bremssystem für ein Kraftfahrzeug.The invention relates to a method for controlling a brake system of a motor vehicle, in particular for controlling a regenerative braking system of a motor vehicle with electronically engageable four-wheel clutch, comprising a number of hydraulic, electronically controllable, each associated with a vehicle axle friction brakes and a generator, the power flow side with a first Vehicle axle is permanently connected to the other and second vehicle axle via an electronically controllable four-wheel clutch. It further relates to a regenerative braking system for a motor vehicle.
In Kraftfahrzeugen können so genannte regenerative Bremssysteme zum Einsatz kommen, bei denen zumindest ein Teil der beim Bremsen aufgebrachten Energie im Fahrzeug gespeichert und später für den Antrieb des Fahrzeug wiederverwendet werden kann. Dadurch kann der Energieverbrauch des Fahrzeugs insgesamt gesenkt, der Wirkungsgrad erhöht und der Betrieb damit wirtschaftlicher gestaltet werden. Kraftfahrzeuge mit einem regenerativen Bremssystem weisen im Hinblick auf variierende Systemanforderungen dazu in der Regel verschiedene Arten von auch als Bremsaktuatoren bezeichneten Bremsen, nämlich üblicherweise einerseits hydraulisch betätigte Reibbremsen und andererseits eine elektrisch-regenerative Bremse, auf. Der Bremsdruck für die Reibbremsen wird in derartigen Systemen zumindest teilweise wie bei konventionellen Reibbremsen über ein Bremsdruckerzeugungsmittel und über die Bremspedalbewegung aufgebracht. Die elektrisch-regenerative Bremse ist in der Regel als elektrischer Generator ausgebildet, über den zumindest ein Teil der gesamten Bremsleistung aufgebracht wird. Die gewonnene elektrische Energie wird in ein Speichermedium wie beispielsweise eine Bordbatterie ein- oder zurückgespeist und kann für den Antrieb des Kraftfahrzeuges über einen geeigneten Antrieb wiederverwendet werden.In vehicles, so-called regenerative braking systems can be used, in which at least part of the energy applied during braking can be stored in the vehicle and later reused for driving the vehicle. As a result, the overall energy consumption of the vehicle can be reduced, the efficiency increased and the operation can be made more economical. Motor vehicles with a regenerative braking system generally have different types of brakes, also referred to as brake actuators, namely, on the one hand, hydraulically actuated friction brakes and, on the other hand, an electrically regenerative brake with respect to varying system requirements. The brake pressure for the friction brakes is applied in such systems at least partially as in conventional friction brakes via a brake pressure generating means and the brake pedal movement. The electric regenerative brake is generally designed as an electrical generator, via which at least part of the total braking power is applied. The electrical energy obtained is fed or fed back into a storage medium such as an on-board battery and can be reused for driving the motor vehicle via a suitable drive.
In derartigen Fahrzeugen mit unterschiedlichen Bremsaktuato- ren ist üblicherweise die Bremskraft-Anforderung in geeigneter Form auf die einzelnen Bremsaktuatoren zu verteilen. Die Aufteilung der Bremsenergie in Anteile der Reibbremsen und in Anteile des elektrischen Generators ist dabei in der Regel vom Sollbremsmoment, dem Ladezustand der Batterie und insbesondere auch dem Betriebsbereich und anderen speziellen Eigenschaften des Generators abhängig. Bevorzugt ist dabei üblicherweise eine weitgehende Nutzung der elektro-regenera- tiven Bremsen oder Generatorbremse, deren Bremsleistung möglichst weitgehend zum Einsatz kommen soll, um somit ein besonders hohes Maß an Bremsenergie zurückgewinnen zu können. Erst wenn das Bremsmoment der Generatorbremse nicht mehr ausreicht, wird das System der Reibungsbremsen zugeschaltet. Das Generatorbremsmoment wird allerdings hierbei in der Regel nur an einer Fahrzeugachse, insbesondere an der Vorderachse umgesetzt.In such vehicles with different Bremsaktuato- ren usually the braking force requirement is distributed in a suitable form to the individual brake actuators. The distribution of braking energy in shares of the friction brakes and shares of the electric generator is usually dependent on the desired braking torque, the state of charge of the battery and in particular the operating range and other special properties of the generator. In this case, preference is usually given to extensive use of the electro-regenerative brakes or generator brake, the braking power of which should be used as extensively as possible in order to be able to recover a particularly high level of braking energy. Only when the braking torque of the generator brake is no longer sufficient, the system of the friction brakes is switched on. However, the generator braking torque is generally only implemented on a vehicle axle, in particular on the front axle.
Dies gilt auch für Kraftfahrzeuge mit schaltbarer 4x4- oder Allradkupplung, bei denen der Generator kraftflussseitig permanent mit einer ersten Fahrzeugachse, üblicherweise der Vorderachse, und über die Allradkupplung mit der zweiten Fahrzeugachse, üblicherweise der Hinterachse, verbunden ist. Bei derartigen Fahrzeugen wird üblicherweise die Allradkupplung beim Bremsen voll geöffnet, so dass das Generatormoment auch bei diesen Fahrzeugen ausschließlich auf die erste Fahrzeugachse oder Vorderachse wirkt.This also applies to motor vehicles with switchable 4x4 or four-wheel clutch, where the generator power flow side permanently with a first vehicle axle, usually the front axle, and the four-wheel clutch with the second Vehicle axle, usually the rear axle is connected. In such vehicles, the four-wheel clutch is usually fully opened during braking, so that the generator torque acts even in these vehicles exclusively on the first vehicle axle or front axle.
Bei derartigen Systemen stellt sich jedoch üblicherweise eine vergleichsweise starke Abweichung von einer voreingestellten oder als ideal angesehenen Bremskraftverteilung ein. Darüber hinaus kann es vergleichsweise frühzeitig zu einer Uberbremsung der Vorderachse und damit zu einem frühzeitigen Eintritt des Anti-Blockier-Systems (ABS) kommen. Sobald das ABS zugeschaltet wird, was üblicherweise mit einer Aktivierung der Reibbremsen und einer Neuverteilung der Bremsmomente einhergeht, kann es zu einem Nickeffekt kommen, da schlagartig eine voreingestellte Bremskraftverteilung zwischen den Achsen eingenommen wird. Da bei derartigen Systemen zudem die Reibbremsen vorzugsweise nur an der Hinterachse zugeschaltet werden, kann es zudem zu stark unterschiedlicher Abnutzung der Bremsbelage an Vorder- und Hinterachse kommen.In such systems, however, there is usually a comparatively large deviation from a preset or considered ideal braking force distribution. In addition, it can come comparatively early to an overbraking of the front axle and thus to an early occurrence of the anti-lock braking system (ABS). As soon as the ABS is switched on, which is usually accompanied by an activation of the friction brakes and a redistribution of the braking torques, a nodding effect can occur because a preset brake force distribution between the axles is abruptly assumed. Since in such systems, moreover, the friction brakes are preferably switched on only at the rear axle, it can also lead to greatly different wear of the brake pad on the front and rear axles.
Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zur Steuerung des Bremssystems eine Kraftfahrzeugs der oben genannten Art anzugeben, mit dem ein besonders gunstiges Bremsverhalten bei Nutzung der Generatorbremse oder elektrisch-regenerativen Bremse erreichbar ist. Zudem soll ein zur Durchfuhrung des Verfahrens besonders geeignetes Bremssystem für ein Kraftfahrzeug der genannten Art angegeben werden.The invention is therefore based on the object to provide a method for controlling the brake system of a motor vehicle of the above type, with a particularly favorable braking behavior when using the generator brake or electric regenerative brake can be achieved. In addition, a particularly suitable for carrying out the method braking system for a motor vehicle of the type mentioned will be specified.
Bezuglich des Verfahrens wird diese Aufgabe erfindungsgemaß gelost, indem nach der Vorgabe eines situationsabhangig er- mittelten Sollbremsmoments für den Generator die Allradkupplung mit einem vorgegebenen Stellwert beaufschlagt wird.With regard to the method, this object is achieved according to the invention by determining, according to the specification of a situation-dependent average rated braking torque for the generator, the four-wheel clutch is applied with a predetermined control value.
Die Erfindung geht dabei von der Überlegung aus, dass gerade bei einem Kraftfahrzeug mit zuschaltbarer Allradkupplung ein besonders gunstiges Bremsverhalten einer elektrisch-regenerativen Bremse erreichbar ist, indem das situationsbedingt vorgesehene Generatorbremsmoment geeignet auf beide Fahrzeugachsen, also insbesondere auf Vorder- und Hinterachse, verteilt wird. Dabei kann insbesondere auch die Einhaltung eines ohnehin als besonders gunstig oder ideal angesehenen Bremskraftverhaltnisses bei der Beaufschlagung der Fahrzeugachsen mit Generatorbremsmoment angestrebt sein. Um dies zu ermöglichen, sollte der Generator kraftflussseitig geeignet mit den Fahrzeugachsen verbunden werden. Dazu ist vorgesehen, die ohnehin elektrisch ansteuerbare Allradkupplung geeignet zu nutzen. Zu diesem Zweck sollte die Allradkupplung mit einem geeignet gewählten Stellwert derart beaufschlagt werden, dass sich eine besondere gunstige Bremsmomentenver- teilung des Generators auf die Fahrzeugachsen ergibt.The invention is based on the consideration that especially in a motor vehicle with shiftable four-wheel drive, a particularly favorable braking behavior of an electric regenerative brake can be achieved by the situationally provided generator braking torque is suitably distributed to both vehicle axles, ie in particular on the front and rear axles. In this case, the observance of a braking force ratio, which in any case is considered to be particularly favorable or ideal, may be sought when the vehicle axles are subjected to a generator braking torque. In order to make this possible, the generator should be suitably connected to the vehicle axles on the power flow side. For this purpose, it is provided to use the already electrically controllable four-wheel drive suitable. For this purpose, the four-wheel clutch should be acted upon with a suitably selected control value so that there is a special favorable Bremsmomentenver- distribution of the generator on the vehicle axles.
In einer vorteilhaften Ausgestaltung kann der Stellwert für die Allradkupplung dabei derart vorgegeben werden, dass der Generator in einem fest vorgegebenen Momentenverhaltnis, vorzugsweise entsprechend einem vorgegebenen idealen Bremskraftverhaltnis, insbesondere in einem Momentenverhaltnis von etwa 70:30, auf die Fahrzeugachsen wirkt. Alternativ kann der Stellwert vorteilhafterweise aber auch situations- abhangig und/oder verzogerungsabhangig ermittelt und geeignet der Allradkupplung vorgegeben werden.In an advantageous embodiment of the manipulated variable for the four-wheel clutch can be specified such that the generator in a fixed torque ratio, preferably according to a predetermined ideal Bremskraftverhaltnis, especially in a moment ratio of about 70:30, acts on the vehicle axles. Alternatively, the manipulated variable can advantageously also be determined depending on the situation and / or depending on the delay and suitably specified for the four-wheel clutch.
Im Hinblick auf sonstige Randbedingungen wie beispielsweise insgesamt verfugbares Generatorbremsmoment, durch den Fah- rerwunsch vorgegebenes Gesamtsollbremsmoment und dergleichen, kann die Allradkupplung vorteilhafterweise verzögerungsabhängig entsprechend eines anhand sonstiger Bedingungen, auf der Grundlage von Erfahrungswissen oder situationsabhängig ermittelten idealen Bremskraftverhältnisses angesteuert werden. Dadurch lässt sich beim regenerativen Bremsen insbesondere auch der volle Fahrbahnreibwert ausnutzen, wobei zudem ein Maximum an Generatorleistung umgesetzt werden kann. Insbesondere wenn das vom Fahrer angeforderte Ge- samtsollbremsmoment das verfügbare Generatorbremsmoment überschreitet, muss ein Teil des Gesamtbremsmoments durch einen zusätzlichen Reibbremsanteil abgedeckt werden. Insbesondere in derartigen Situationen wird vorteilhafterweise der Stellwert für die Allradkupplung derart vorgegeben, dass das Generatorbremsmoment mit einem situationsabhängig aus einem vorgegebenen oder idealen Bremskraftverhältnis ermittelten Bremsmoment auf die erste, permanent mit dem Generator verbundene Fahrzeugachse, insbesondere die Vorderachse, einwirkt. Die Allradkupplung wird dabei vorzugsweise derart angesteuert, dass der Generator mit dem restlichen verfügbaren Generatorbremsmoment auf die zweite Fahrzeugachse wirkt, wobei das im Hinblick auf das angeforderte Gesamtsollbrems- moment und die ideale Bremskraftverteilung noch zusätzlich für die zweite Fahrzeugachse oder Hinterachse benötigte Bremsmoment über die der Hinterachse zugeordneten Reibbremsen aufgebracht wird. Dazu werden die der zweiten Fahrzeugachse zugeordneten Reibbremsen vorteilhafterweise geeignet zugeschaltet, so dass insgesamt ein situationsabhängig aus einem vorgegebenen Bremskraftverhältnis ermitteltes Bremsmoment auf die zweite Fahrzeugachse wirkt.With regard to other boundary conditions such as total available generator braking torque, by the rerwunsch predetermined total target braking torque and the like, the four-wheel drive can be controlled advantageously delay dependent according to an on the basis of other conditions, based on empirical knowledge or situation-dependent determined ideal braking force ratio. As a result, in particular, the full road friction coefficient can also be utilized in regenerative braking, with it also being possible to implement a maximum of generator power. In particular, when the total nominal braking torque requested by the driver exceeds the available generator braking torque, part of the total braking torque must be covered by an additional friction brake component. In particular, in such situations advantageously the control value for the four-wheel drive is set such that the generator braking torque with a situation-dependent determined from a predetermined or ideal braking force braking torque on the first, permanently connected to the generator vehicle axle, in particular the front axle acts. The four-wheel drive is preferably controlled such that the generator with the remaining available generator braking torque acts on the second vehicle axle, wherein the required in view of the total Sollbrems- and ideal braking force distribution additionally required for the second vehicle axle or rear axle braking torque on the rear axle associated friction brakes is applied. For this purpose, the friction brakes associated with the second vehicle axle are advantageously switched on suitably so that, overall, a braking torque determined depending on the situation from a predetermined braking force ratio acts on the second vehicle axle.
Vorteilhafterweise wird der Stellwert für die Allradkupplung erst dann ausgegeben, wenn das insgesamt angeforderte Brems- moment einen vorgegebenen Grenzwert übersteigt. Damit kann eine übermäßige Erhöhung der Lastwechselzahlen der Allradkupplung vermieden werden. Die Aktivierung der Allradkupplung oberhalb des vorgegebenen Grenzwerts erfolgt dabei vorteilhafterweise derart, dass ab Erreichen des Grenzwerts zunächst das Kupplungsverhältnis so in Abhängigkeit vom angeforderten Bremsmoment angesteuert wird, dass das an der ersten Fahrzeugachse oder Vorderachse applizierte Generatormoment konstant bleibt und lediglich an der zweiten Fahrzeugachse oder Hinterachse weiteres Generatormoment aufgebaut wird, bis das Momentenverhältnis an den Fahrzeugachsen der idealen Bremskraftverteilung entspricht.Advantageously, the control value for the four-wheel clutch is output only when the total requested brake moment exceeds a predetermined limit. Thus, an excessive increase in the load change numbers of the four-wheel drive can be avoided. The activation of the all-wheel clutch above the predetermined limit value is advantageously carried out such that when the limit value is reached, first the clutch ratio is controlled as a function of the requested braking torque, that the generator torque applied to the first vehicle axle or front axle remains constant and only at the second vehicle axle or rear axle is constructed further generator torque until the torque ratio corresponds to the vehicle axles of the ideal brake force distribution.
Bezüglich des Bremssystems wird die genannte Aufgabe gelöst, indem die elektronisch ansteuerbare Allradkupplung, die die zweite Fahrzeugachse kraftschlussseitig betriebspunktabhängig mit dem Generator verbindet, von einer Bremsensteuereinheit mit einem Stellwert beaufschlagt ist. Bei einem derartigen Bremssystem ist die Bremsensteuereinheit somit derart ausgelegt, dass sie der Allradkupplung einen Stellwert zuführen kann, so dass die Ansteuerung der Allradkupplung im Rahmen des Bremsenkonzepts überhaupt ermöglicht ist.With regard to the braking system, the stated object is achieved by the electronically controllable four-wheel clutch, which connects the second vehicle axle frictional side operating point-dependent with the generator, is acted upon by a brake control unit with a control value. In such a brake system, the brake control unit is thus designed such that it can supply the four-wheel clutch, a control value, so that the activation of the all-wheel drive is in the context of the brake concept ever made possible.
Die mit der Erfindung erzielten Vorteile bestehen insbesondere darin, dass durch die Beaufschlagung der Allradkupplung mit einem Stellwert in Abhängigkeit von den Bremserfordernissen die elektrisch-regenerative Bremse in besonders günstiger Weise nutzbar ist. Die Allradkupplung wird dabei bei Bremsungen, die ganz oder teilweise über die regenerative Bremse erfolgen, zu einem gewissen Grad derart geschlossen, dass sich das Bremsmoment des regenerativen Bremsens in einem bestimmten, als besonders günstig erachteten Verhältnis auf beide Fahrzeugachsen verteilt. Ein Ausfuhrungsbeispiel der Erfindung wird anhand einer Zeichnung naher erläutert. Darin zeigen:The advantages achieved by the invention are in particular that by applying the four-wheel clutch with a control value as a function of the braking requirements, the electric regenerative brake is used in a particularly favorable manner. The four-wheel clutch is closed during braking, which take place wholly or partly via the regenerative brake, to a certain extent such that the braking torque of the regenerative braking distributed in a certain, considered particularly favorable ratio on both vehicle axles. An embodiment of the invention will be explained in more detail with reference to a drawing. Show:
Fig. 1 schematisch ein Bremssystem eines Kraftfahrzeugs, undFig. 1 shows schematically a brake system of a motor vehicle, and
Fig. 2 ein Diagramm zur Verteilung von Momentenanteilen. Das Bremssystem 1 gemäß Fig. 1 ist einem Kraftfahrzeug zugeordnet und umfasst in der Art eines Hybridsystems ein hydraulisches Untersystem und ein elektrisch-regeneratives Untersystem. Der hydraulische Anteil des Bremssystems 1 umfasst eine Anzahl von hydraulischen, elektronisch ansteuerbaren Reibbremsen 2, 4, die jeweils an einem Rad 6 angeordnet sind. Die Reibbremsen 2 sind dabei der Vorderachse oder ersten Fahrzeugachse 8 des Kraftfahrzeugs zugeordnet, wohingegen die Reibbremsen 4 der Hinterachse oder zweiten Fahrzeugachse 10 zugeordnet sind. Die Reibbremsen 2, 4 sind über ein nicht naher dargestelltes Bremshydrauliksystem konventioneller Bauart mit einer Hyraulikflussigkeit beaufschlagbar und können somit aktiviert werden. Zur Ansteuerung der Reibbremsen 2, 4 sind diese über Ansteuerleitungen 12 mit einer zentralen Bremsensteuereinheit 14 verbunden, die beispielsweise über die Ansteuerleitungen 12 Hydraulikventile der jeweiligen Reibbremsen 2, 4 gezielt ansteuern kann, um damit einen kontrollierten Druckaufbau an der jeweiligen Reibbremse 2, 4 zu ermöglichen. Durch die Bremsensteuereinheit 14 ist damit eine radindividuelle Ansteuerung der Reibbremsen 2, 4 ermöglicht. Bedarfsweise oder situationsabhan- gig kann die Bremsensteuereinheit 14 dabei insbesondere als ABS- oder ESP-Regelung wirken.Fig. 2 is a diagram for the distribution of torque components. The brake system 1 according to FIG. 1 is associated with a motor vehicle and comprises in the manner of a hybrid system a hydraulic subsystem and an electrically regenerative subsystem. The hydraulic portion of the brake system 1 comprises a number of hydraulic, electronically controllable friction brakes 2, 4, which are each arranged on a wheel 6. The friction brakes 2 are assigned to the front axle or first vehicle axle 8 of the motor vehicle, whereas the friction brakes 4 are assigned to the rear axle or second vehicle axle 10. The friction brakes 2, 4 are acted upon by a not shown near brake hydraulic system of conventional design with a Hyraulikflussigkeit and can thus be activated. For controlling the friction brakes 2, 4, these are connected via control lines 12 to a central brake control unit 14, which can selectively control hydraulic valves of the respective friction brakes 2, 4, for example via the control lines, in order to allow a controlled pressure build-up on the respective friction brake 2, 4 , By the brake control unit 14 so that a wheel-individual control of the friction brakes 2, 4 allows. If required or as a function of the situation, the brake control unit 14 can act in particular as ABS or ESP control.
Über den hydraulischen Anteil hinaus umfasst das Bremssystem 1 auch einen elektrisch-regenerativen Anteil, über den beim Bremsen eine möglichst weitgehende Rückgewinnung der verbrauchten Energie erreicht werden soll. Das elektrisch-regenerative Untersystem des Bremssystems 1 umfasst dabei einen Generator 20, der kraftflussseitig über eine Welle 22 mit einem Differenzialgetriebe 24 und über dieses mit der ersten Fahrzeugachse 8 permanent verbunden ist. Im Antriebsmodus treibt der Generator 20 dabei die Vorderachse oder erste Fahrzeugachse 8 des Kraftfahrzeugs an, wohingegen im Bremsmodus der Generator 20 seinerseits von der ersten Fahrzeugachse 8 angetrieben wird und dabei elektrische Energie erzeugt. Zum Speichern der dabei angefallenen elektrischen Energie ist der Generator 20 in nicht näher dargestellter Weise mit einer geeignet gewählten Batterieeinheit verbunden. Um bei derartigen Bremsphasen eine geeignete Einbindung des elektrisch-regenerativen Untersystems in den Bremsvorgang zu ermöglichen und insbesondere die Verteilung der Momentenanteile, die zur Erzeugung des Gesamtbremsmoments vom hydraulischen Anteil und vom elektrisch-regenerativen Anteil des Bremssystems 1 aufgebracht werden, an vorgegebene oder gewünschte Momentenverteilungen angepasst halten zu können, ist der Generator 20, wie durch den Pfeil 25 angedeutet, ebenfalls von der Bremsensteuereinheit 14 ansteuerbar. Durch die Ausgabe geeigneter Stellwerte an die hydraulischen Reibbremsen 2, 4 einerseits und an den Generator 20 andererseits kann die Bremsensteuereinheit 14 somit zur Einhaltung vorgegebener Momentenaufteilungen beitragen.Beyond the hydraulic portion, the brake system 1 also includes an electric regenerative portion via which the Braking as far as possible recovery of the energy consumed is to be achieved. The electric regenerative subsystem of the brake system 1 comprises a generator 20, which is permanently connected via a shaft 22 to a differential gear 24 and via this to the first vehicle axle 8. In the drive mode, the generator 20 thereby drives the front axle or first vehicle axle 8 of the motor vehicle, whereas in the braking mode the generator 20 in turn is driven by the first vehicle axle 8 and thereby generates electrical energy. To store the resulting electrical energy, the generator 20 is connected in a manner not shown with a suitably selected battery unit. In order to enable a suitable integration of the electric regenerative subsystem in the braking operation in such braking phases and in particular the distribution of the torque components, which are applied to generate the total braking torque of the hydraulic portion and the electric regenerative portion of the brake system 1, adapted to predetermined or desired torque distributions to hold, the generator 20, as indicated by the arrow 25, also driven by the brake control unit 14. By the output of suitable control values to the hydraulic friction brakes 2, 4 on the one hand and to the generator 20 on the other hand, the brake control unit 14 thus contribute to maintaining predetermined torque distributions.
Das Kraftfahrzeug ist im Ausführungsbeispiel mit einem zuschaltbaren Allradantrieb oder 4x4-Antrieb versehen. Dazu ist der Generator 20 kraftflussseitig über eine Welle 26, in die eine elektronisch ansteuerbare Allradkupplung 28 geschaltet ist, und über ein Differenzial 30 mit der Hinterachse oder zweiten Fahrzeugachse 10 des Kraftfahrzeugs ver- bunden. Für eine bedarfsweise oder situationsabhangige Zu- schaltung des Allradantriebs im Antriebsmodus des Kraftfahrzeugs ist die Allradkupplung 28 dabei in nicht naher dargestellter Weise mit Stellwerten aus einem bordeigenen Regelsystem beaufschlagbar, die in vom Fahrerwunsch abhangiger oder von der Bordelektronik vorgegebener Weise im Antriebsmodus ein Offnen oder Schließen der Allradkupplung 28 bewirken .The motor vehicle is provided in the exemplary embodiment with a switchable four-wheel drive or 4x4 drive. For this purpose, the generator 20 is on the power flow side via a shaft 26, in which an electronically controllable four-wheel clutch 28 is connected, and via a differential 30 with the rear axle or second vehicle axle 10 of the motor vehicle. prevented. For an on-demand or situation-dependent connection of the four-wheel drive in the drive mode of the motor vehicle, the four-wheel clutch 28 in a manner not shown acted upon with control values from an on-board control system in the driver's choice depending or predetermined by the on-board electronics in the drive mode opening or closing the Four-wheel clutch 28 effect.
Das Bremssystem 1 ist in spezifischer Weise dafür ausgelegt, den zuschaltbaren Allradantrieb des Kraftfahrzeugs in die Bremsvorgange und insbesondere in die Momentenaufteilungen zwischen hydraulischen Anteilen und elektrisch-regenerativen Anteilen einerseits und zwischen den Fahrzeugachsen 8, 10 andererseits besonders gunstig einzubinden. Um dies zu ermöglichen, ist, wie dies durch den Pfeil 32 angedeutet ist, die Allradkupplung 28 ebenfalls durch die Bremsensteuereinheit 14 ansteuerbar und mit einem Stellwert beaufschlagbar. Dadurch kann sichergestellt werden, dass die Allradkupplung 28 bei Bremsungen, die ganz oder teilweise über die regenerative Bremse erfolgen, zu einem gewissen Grad geschlossen werden kann, so dass sich das Bremsmoment des regenerativen Bremsens oder des Generators 20 in einem gewünschten Verhältnis auf die Fahrzeugachsen 8, 10 verteilt. Damit ist insbesondere erreichbar, dass der Fahrbahnreibwert besonders weitgehend ausgenutzt wird, da nunmehr auch im elektrischregenerativen Modus über beide Fahrzeugachsen 8, 10 gebremst werden kann. Des Weiteren kann das Bremssystem 1 dafür ausgelegt sein, eine voreingestellte oder als ideal erkannte Bremskraftverteilung zwischen den beiden Fahrzeugachsen 8, 10 weitestgehend einzuhalten, um damit eine besonders hohe Fahrzeugstabilitat beim Bremsen und auch die Einhaltung von besonders hohen Komfortanspruchen des Fahrers zu ermogli- chen .The braking system 1 is designed in a specific way to integrate the switchable four-wheel drive of the motor vehicle in the braking process and in particular in the moment divisions between hydraulic components and electric regenerative shares on the one hand and between the vehicle axles 8, 10 on the other hand particularly favorable. To make this possible, as indicated by the arrow 32, the four-wheel clutch 28 can also be controlled by the brake control unit 14 and acted upon by a control value. In this way, it can be ensured that the four-wheel drive clutch 28 can be closed to a certain extent during braking, which takes place wholly or partly via the regenerative brake, so that the braking torque of the regenerative braking or the generator 20 is applied to the vehicle axles 8 in a desired ratio , 10 distributed. This makes it possible, in particular, for the road friction coefficient to be exploited to a particularly large extent, since it is now also possible to brake in the electrically regenerative mode via both vehicle axles 8, 10. Furthermore, the brake system 1 can be designed to largely comply with a pre-set or ideal brake force distribution between the two vehicle axles 8, 10 in order to ensure particularly high vehicle stability during braking and also compliance with particularly high driver comfort requirements. chen.
Das Bremssystem 1 könnte dabei, insbesondere durch geeignete Auslegung der Bremsensteuereinheit 14, derart ausgelegt sein, dass beim elektrisch-regenerativen Bremsen das regenerative Bremsmoment in einem festen Verhältnis auf die Fahrzeugachsen 8, 10, beispielsweise in einem Verhältnis von 70:30 für Vorderachse zu Hinterachse, aufgeteilt wird, wobei die Allradkupplung 28 mit einem dementsprechenden Stellwert von der Bremsensteuereinheit 14 beaufschlagt würde. Im Ausführungsbeispiel ist das Bremssystem 1 aber derart ausgelegt, dass der Stellwert für die Allradkupplung 28 von der Bremsensteuereinheit 14 situationsabhängig oder verzögerungsabhängig derart ausgegeben wird, dass als besonders günstig empfundene Bremsresultate erzielt werden können.The brake system 1 could, in particular by appropriate design of the brake control unit 14, be designed such that the regenerative braking torque in the electric regenerative braking in a fixed ratio to the vehicle axles 8, 10, for example in a ratio of 70:30 for front to rear axle is split, wherein the four-wheel clutch 28 would be acted upon by a corresponding control value from the brake control unit 14. In the exemplary embodiment, however, the brake system 1 is designed such that the control value for the four-wheel clutch 28 is output by the brake control unit 14 in a situation-dependent or delay-dependent manner in such a way that braking results which are perceived as particularly favorable can be achieved.
Zur Erläuterung der Kriterien, nach denen der Stellwert für die Allradkupplung 28 ausgegeben wird, dient die diagrammatische Darstellung in Fig. 2. Das Diagramm nach Fig. 2 zeigt als Funktion des auf der X-Achse abgetragenen Parameters Gesamtbremsmoment oder Fahrerwunsch M auf der Y-Achse abgetragen einzelne Momentenbeiträge oder -anteile. Die Gerade 40 gibt dabei ebenfalls den Fahrerwunsch wieder und repräsentiert somit in jedem Fall das insgesamt durch die Summe des elektrisch-regenerativen Bremsbeitrags und des hydraulischen Bremsbeitrags an allen vier Rädern 6 aufzubringende Sollbremsmoment. Zur weiteren Orientierung dienen die Geraden 42 und 44, die für eine als ideal erkannte Bremskraftverteilung die gewünschten Momentenanteile an der Vorderachse (Gerade 42) bzw. an der Hinterachse (Gerade 44) repräsentieren. Die durch die Geraden 42, 44 repräsentierte Aufteilung des Gesamtbremsmoments auf einen Vorderachsenanteil und einen Hinterachsenanteil entspricht dabei einem so genannten idealen Bremskraftverhältnis, das beispielsweise anhand von Stabilitätsbetrachtungen, Sicherheitskriterien und dergleichen ermittelt worden ist. Es ist für das Bremssystem 1 grundsätzlich wünschenswert, die Momentenverteilung zwischen Vorderachse und Hinterachse an die durch die Geraden 42, 44 repräsentierten Werte anzunähern.The diagrammatic representation in FIG. 2 is used to explain the criteria according to which the manipulated variable for the four-wheel drive 28 is output. The diagram according to FIG. 2 shows as a function of the parameter total braking torque or driver command M plotted on the X-axis on the Y-axis. Axis removed individual moment contributions or shares. In this case, the straight line 40 likewise represents the driver's wish and thus represents in each case the desired braking torque to be applied overall by the sum of the electric regenerative braking contribution and the hydraulic braking contribution to all four wheels 6. For further orientation, the straight lines 42 and 44, which represent the desired torque components on the front axle (straight line 42) or on the rear axle (straight line 44) for a braking force distribution recognized as ideal. The distribution of the total braking torque represented by the straight lines 42, 44 to a front axle portion and a rear axle portion corresponds to a so-called ideal Brake force ratio, which has been determined for example on the basis of stability considerations, safety criteria and the like. It is basically desirable for the brake system 1 to approximate the torque distribution between the front axle and the rear axle to the values represented by the straight lines 42, 44.
Abhängig vom insgesamt aufzubringenden Bremsmoment ist das Bremssystem 1 zur Ausgabe bestimmter Momentenanteile an die einzelnen Bremsen ausgelegt, wobei der an die Allradkupplung 28 ausgegebene Stellwert jeweils entsprechend gewählt wird. Die Momentenverteilung erfolgt dabei in Abhängigkeit von der Größe des insgesamt aufzubringenden Bremsmoments M nach etwas unterschiedlichen Kriterien, wie im Folgenden näher erläutert wird. Zur Erläuterung der Regelungsgrundsätze ist der Parameterbereich des insgesamt aufzubringenden Bremsmoments M dabei in mehrere Phasen oder Intervalle Ii bis I5 aufgeteilt, in denen die jeweilige Momentenvorgabe jeweils etwas unterschiedlich erfolgt.Depending on the braking torque to be applied overall, the brake system 1 is designed to output certain torque components to the individual brakes, the control value output to the four-wheel clutch 28 being respectively selected accordingly. The torque distribution is carried out depending on the size of the total applied braking torque M according to slightly different criteria, as will be explained in more detail below. To explain the principles of control, the parameter range of the braking torque M to be applied overall is divided into a plurality of phases or intervals Ii to I 5 , in which the respective torque input takes place somewhat differently in each case.
In der ersten Phase oder im Intervall Ii ist die insgesamt aufzubringende Bremsmoment, repräsentiert durch die Gerade 40, kleiner als ein durch die strichlierte Gerade 46 wiedergegebener vorgegebener Grenzwert. In diesem Bereich erfolgt keine Aktivierung der Allradkupplung 28; das gesamte Bremsmoment wird in diesem Bereich durch einen elektrisch-regenerativen Momentenanteil an der Vorderachse oder ersten Fahrzeugachse 8, also bei geöffneter Allradkupplung 28, aufgebracht. Im Diagramm nach Fig. 2 kommt dies dadurch zum Ausdruck, dass im Bereich des ersten Intervalls Ii die den Anteil des regenerativen Bremsmoments an der ersten Fahrzeugachse 8 repräsentierende Linie 50 mit der den Fahrerwunsch oder das insgesamt aufzubringende Bremsmoment charakterisie- renden Gerade 40 zusammenfällt. Die Betriebsweise gemäß Intervall Ii für vergleichsweise kleine insgesamt aufzubringende Bremsmomente ist insbesondere vorteilhaft, um eine übermäßige Erhöhung der Lastwechselzahlen der Allradkupplung 28 zu vermeiden.In the first phase or interval Ii, the braking torque to be applied overall, represented by the straight line 40, is smaller than a predetermined limit value represented by the dashed straight line 46. In this area, no activation of the four-wheel clutch 28 takes place; the entire braking torque is applied in this area by an electrically regenerative torque component on the front axle or first vehicle axle 8, that is to say when the all-wheel drive clutch 28 is open. In the diagram according to FIG. 2, this is expressed by the fact that in the region of the first interval Ii the line 50 representing the proportion of the regenerative braking torque on the first vehicle axle 8 is characterized by the driver's request or the total braking torque to be applied. Just 40 coincides. The mode of operation according to interval Ii for comparatively small braking torques to be applied overall is particularly advantageous in order to avoid an excessive increase in the numbers of load cycles of the all-wheel drive clutch 28.
Bei Erhöhung des Fahrerwunsches oder insgesamt aufzubringenden Bremsmoments M über den genannten Grenzwert hinaus erfolgt die Momentenverteilung gemäß der zweiten Phase oder dem Intervall I2. In diesem Bereich ist vorgesehen, über eine gezielte Ansteuerung der Allradkupplung 28 nunmehr sukzessive zusätzliches elektrisch-regeneratives Bremsmoment auch an der Hinterachse oder zweiten Fahrzeugachse 8 aufzubauen. Im Intervall I2 wird somit auch bei weiter steigendem Fahrerwunsch das an die Vorderachse oder erste Fahrzeugachse 8 abgegebene elektrisch-regenerative Bremsmoment konstant gehalten; dementsprechend verläuft im Intervall I2 die Linie 50 horizontal. Um dem im Intervall I2 zunehmend steigenden Fahrerwunsch Rechnung zu tragen, wird in gleichem Maße aber elektrisch-regeneratives Bremsmoment an der Hinterachse aufgebaut; dies ist im Diagramm durch die diesen Momentenanteil wiedergebende Linie 52 repräsentiert. Auch bei weiter steigendem Fahrerwunsch wird das elektrisch-regenerative Moment an der Vorderachse weiter konstant gehalten und ausschließlich an der Hinterachse weiteres elektrisch-regeneratives Bremsmoment aufgebaut, so lange, bis das ideale Bremskraftverhältnis zwischen diesen Momentbeiträgen erreicht ist. Dies ist gegeben, wenn die Linien 50, 52 die das ideale Bremskraftverhältnis wiedergebenden Geraden 42, 44 schneiden .When increasing the driver's request or total applied braking torque M above the limit mentioned above, the torque distribution takes place according to the second phase or the interval I 2 . In this area, it is provided that a targeted activation of the four-wheel drive clutch 28 can now be used successively to build up additional electrical-regenerative braking torque also on the rear axle or second vehicle axle 8. In the interval I 2 , the electric-regenerative braking torque output to the front axle or first vehicle axle 8 is therefore kept constant even with a further increase in the driver's request; Accordingly, in the interval I 2, the line 50 runs horizontally. In order to take into account the increasingly increasing driver request in the interval I 2 , however, electrically regenerative braking torque is built up on the rear axle to the same extent; this is represented in the diagram by the line 52 representing this moment proportion. Even with a further increase in the driver's request, the electric regenerative torque is kept constant at the front axle and built exclusively on the rear axle further electric regenerative braking torque, so long until the ideal brake force ratio between these torque contributions is reached. This is the case when the lines 50, 52 intersect the straight line 42, 44 representing the ideal braking force ratio.
Oberhalb dieser Schnittpunkte, also bei noch höherem Fahrerwunsch oder aufzubringendem Gesamtbremsmoment M, beginnt die dritte Phase oder das Intervall I3. In diesem Intervall wird die Allradkupplung 28 derart mit einem Stellwert beaufschlagt, dass das an die Fahrzeugachsen 8, 10 jeweils weiter gegebene elektrisch-regenerative Moment jeweils dem Anteil der idealen Bremskraftverteilung entspricht. Gerade in dieser Phase lässt sich auch beim regenerativen Bremsen der volle Fahrbahnreibwert ausnutzen und gleichzeitig ein Maximum an Generatorleistung umsetzen.Above these intersections, so with even higher driver's request or applied total braking torque M, the begins third phase or the interval I 3 . In this interval, the four-wheel clutch 28 is acted upon by a control value that corresponds to the vehicle axles 8, 10 each further given electrical-regenerative torque in each case the proportion of the ideal brake force distribution. Especially in this phase, the full road friction coefficient can also be exploited during regenerative braking and at the same time implement maximum generator power.
Bei noch weiter steigendem Fahrerwunsch oder aufzubringendem Gesamtbremsmoment wird ein Punkt erreicht, bei dem der Fahrerwunsch oder das insgesamt aufzubringende Gesamtbremsmoment das vom Generator 20 überhaupt insgesamt abrufbare Bremsmoment übersteigt. Dieses maximal verfügbare regenerative Bremsmoment ist im Diagramm durch die strichlierte Linie 54 wiedergegeben. Die vierte Phase oder das Intervall I4 beginnt somit an dem Punkt, an dem die Summe der Momentenanteile gemäß Linie 50 und gemäß Linie 52 gleich dem durch die strichlierte Gerade 54 gegebenen Wert ist. Ab diesem Wert für den Fahrerwunsch ist über die elektrisch-regenerative Bremse hinaus die Zuschaltung der Reibbremsen erforderlich. In dieser Phase wird der Stellwert für die Allradkupplung 28 derart vorgegeben, dass das an die erste Fahrzeugachse 8 oder die Vorderachse ausgegebene elektrisch-regenerative Bremsmoment nach wie vor dem aus der idealen Bremskraftverteilung für die Vorderachse übermittelten Momentenanteil entspricht; dementsprechend fallen im Intervall I4 die Linie 50 und die Gerade 42 ebenfalls zusammen. Die Allradkupplung 28 wird dabei derart angesteuert, dass das restliche von der elektrisch-regenerativen Bremse verfügbare Bremsmoment an die Hinterachse oder zweite Fahrzeugachse 10 weitergegeben wird. Je stärker dabei gemäß steigendem Fahrerwunsch der Anteil des an die Vorderachse abzugebenden elektrisch-regene- rativen Bremsmoments ansteigt, desto stärker fällt notwendigerweise der an die Hinterachse abgegebene Anteil elektrisch-regenerativen Bremsmoments; dementsprechend fällt die Linie im Intervall I4 mit zunehmenden Fahrerwunsch ab. Um dies zu kompensieren, werden die Reibbremsen 4 an der Hinterachse 10 zunehmend derart zugeschaltet, dass das insgesamt auf die zweite Fahrzeugachse 10 wirkende Bremsmoment, zusammengesetzt aus elektrisch-regenerativem Bremsmoment und hydraulischem Bremsmoment, dem Anteil gemäß dem idealen Bremskraftverhältnis entspricht. Der hydraulische Anteil an Bremsmoment an der zweiten Fahrzeugachse 10 wird im Diagramm gemäß Fig. 2 dabei durch die Linie 56 repräsentiert. In dieser Phase wird die Allradkupplung 28 somit gerade derart geöffnet, dass sich durch die damit ergebende Verlagerung des Generatorbremsmoments von der Hinter- zur Vorderachse und den Aufbau von Reibbremsmoment an der Hinterachse die vorgegebene, möglichst ideale Bremskraftverteilung ergibt.With still increasing driver demand or applied total braking torque, a point is reached at which the driver's request or the total applied braking torque exceeds the total of the generator 20 retrievable braking torque. This maximum available regenerative braking torque is shown in the diagram by the dashed line 54. The fourth phase or the interval I 4 thus begins at the point at which the sum of the torque components according to line 50 and according to line 52 is equal to the value given by the dashed line 54. From this value for the driver's request, the engagement of the friction brakes is required in addition to the electric regenerative brake. In this phase, the control value for the four-wheel clutch 28 is set such that the output to the first vehicle axle 8 or the front axle electric regenerative braking torque still corresponds to the transmitted from the ideal braking force distribution for the front axle torque component; Accordingly, in the interval I 4, the line 50 and the line 42 also coincide. The four-wheel drive clutch 28 is controlled in such a way that the remaining braking torque available from the electric regenerative brake is forwarded to the rear axle or second vehicle axle 10. The greater the proportion of electric-rain to be delivered to the front axle according to increasing driver demand. rative braking torque increases, the more necessarily falls the output to the rear axle share electric regenerative braking torque; Accordingly, the line drops in the interval I 4 with increasing driver demand. In order to compensate for this, the friction brakes 4 on the rear axle 10 are increasingly switched in such that the total braking torque acting on the second vehicle axle 10, composed of electrically regenerative braking torque and hydraulic braking torque, corresponds to the proportion according to the ideal braking force ratio. The hydraulic component of the braking torque on the second vehicle axle 10 is represented by the line 56 in the diagram according to FIG. 2. In this phase, the four-wheel drive 28 is thus just opened so that the resulting, as ideal as possible brake force distribution results from the resulting shift of the generator braking torque from the rear to the front axle and the structure of friction brake on the rear axle.
Bei noch weiter steigendem Fahrerwunsch oder insgesamt aufzubringendem Bremsmoment M wird schließlich der Punkt erreicht, bei dem das verfügbare Generatorbremsmoment nicht mehr ausreicht, um den Anteil an der Vorderachse gemäß der idealen Bremskraftverteilung aufzubringen. Im Diagramm entspricht dies dem Punkt, an dem die Gerade 42 die Linie 54 repräsentativ für das maximal aufbringbare Generatorbremsmoment schneidet. An diesem Punkt beginnt die fünfte Phase oder das Intervall I5. In dieser Phase wird das gesamte aufbringbare Generatorbremsmoment an der Vorderachse gehalten; dementsprechend verläuft in diesem Bereich die Linie 50 horizontal. Das gewünschte Bremsmoment an der Hinterachse wird ausschließlich durch die Reibbremsen 4 aufgebracht; dementsprechend verläuft im Intervall I5 die Linie 56 deckungsgleich mit der Gerade 44. Das noch zusätzlich benötigte Bremsmoment an der Vorderachse wird in diesem Fall durch weitere Ansteuerung der Reibbremsen 2 aufgebracht, deren Momentenanteil im Diagramm durch die Linie 58 repräsentiert ist .With still increasing driver demand or total applied braking torque M, the point is eventually reached at which the available generator braking torque is no longer sufficient to apply the proportion of the front axle according to the ideal brake force distribution. In the diagram, this corresponds to the point at which the line 42 intersects the line 54 representative of the maximum applicable generator braking torque. At this point, the fifth phase or interval I 5 begins. In this phase, the entire applicable generator braking torque is held on the front axle; accordingly, line 50 runs horizontally in this area. The desired braking torque on the rear axle is applied exclusively by the friction brakes 4; Accordingly, in the interval I 5, the line 56 is congruent with the straight line 44. The additionally required Braking torque at the front axle is applied in this case by further control of the friction brakes 2, the moment proportion is represented in the diagram by the line 58.
Durch die genannte Betriebsweise des Bremssystems 1 wird bei hoher Stabilität und betrieblicher Sicherheit die elektrisch-regenerative Bremse besonders wirkungsvoll genutzt. Beim Eintritt in eine ABS- oder ESP-Regelung wird die Allradkupplung 28 jedoch sofort geöffnet und kein Generatormoment mehr angefordert, um eine radindividuelle Regelung zu ermöglichen . Due to the aforementioned mode of operation of the brake system 1, the electric regenerative brake is used particularly effectively with high stability and operational safety. When entering an ABS or ESP control, however, the four-wheel clutch 28 is opened immediately and no more generator torque required to allow a wheel-individual control.
BezugszeichenlisteLIST OF REFERENCE NUMBERS
1 Bremssystem1 brake system
2, 4 Reibbremsen2, 4 friction brakes
6 Rad6 wheel
8 Vorderachse / erste Fahrzeugachse8 front axle / first vehicle axle
10 Hinterachse / zweite Fahrzeugachse10 rear axle / second vehicle axle
12 AnsteuerIeitungen12 control lines
14 Bremsensteuereinheit14 brake control unit
20 Generator20 generator
22 Welle22 wave
24 Differenzialgetriebe24 differential gearbox
25 Pfeil25 arrow
26 Welle26 wave
28 Allradkupplung28 four-wheel clutch
30 Differenzial30 differential
32 Pfeil32 arrow
40 Gerade40 Straight
42 Gerade42 Straight
44 Gerade44 Straight
46 strichlierte Gerade46 dashed line
50, 52 Linien50, 52 lines
54 strichlierte Gerade54 dashed straight line
56, 58 Linien56, 58 lines
Ii bis I5 IntervalleIi to I 5 intervals
M Fahrerwunsch / Bremsmoment M driver request / braking torque

Claims

Patentansprüche claims
1. Verfahren zur Steuerung eines Bremssystems (1) eines Kraftfahrzeugs, das eine Anzahl von hydraulischen, elektronisch steuerbaren, jeweils einer Fahrzeugachse (8, 10) zugeordneten Reibbremsen (2, 4) und einen Generator (20) umfasst, der kraftflussseitig mit einer ersten Fahrzeugachse (8) permanent und mit der anderen, zweiten Fahrzeugachse (10) über eine elektronisch ansteuerbare Allradkupplung (28) verbunden ist, bei dem nach der Vorgabe eines situationsabhängig ermittelten Sollbremsmoments für den Generator (20) die Allradkupplung (28) mit einem vorgegebenen Stellwert beaufschlagt wird.1. A method for controlling a brake system (1) of a motor vehicle, comprising a number of hydraulic, electronically controllable, each a vehicle axle (8, 10) associated friction brakes (2, 4) and a generator (20), the power flow side with a first Vehicle axle (8) permanently and with the other, second vehicle axle (10) via an electronically controllable four-wheel clutch (28) is connected, in which after the specification of a situation-dependent determined desired braking torque for the generator (20) the four-wheel clutch (28) with a predetermined control value is charged.
2. Verfahren nach Anspruch 1, bei dem der Stellwert derart vorgegeben wird, dass der Generator (20) in einem fest vorgegebenen Momentenverhältnis, insbesondere in einem Momentenverhältnis von etwa 70:30, auf die Fahrzeugachsen2. The method of claim 1, wherein the control value is set such that the generator (20) in a fixed torque ratio, in particular in a torque ratio of about 70:30, on the vehicle axles
(8, 10) wirkt.(8, 10) acts.
3. Verfahren nach Anspruch 1, bei dem der Stellwert situationsabhängig und/oder verzögerungsabhängig vorgegeben wird.3. The method of claim 1, wherein the control value is specified depending on the situation and / or delay dependent.
4. Verfahren nach Anspruch 3, bei dem der Stellwert derart vorgegeben wird, dass der Generator (20) mit einem situationsabhängig aus einem vorgegebenen Bremskraftverhältnis ermittelten Bremsmoment (M) auf die erste Fahrzeugachse4. The method of claim 3, wherein the control value is set such that the generator (20) with a situation-dependent determined from a predetermined braking force braking torque (M) on the first vehicle axle
(8) und mit dem restlichen verfügbaren Generatorbremsmoment auf die zweite Fahrzeugachse (10) wirkt.(8) and acts on the second vehicle axle (10) with the remaining available generator braking torque.
5. Verfahren nach Anspruch 4, bei dem die der zweiten Fahrzeugachse (10) zugeordneten Reibbremsen (4) derart zuge- schaltet werden, dass insgesamt ein situationsabhängig aus einem vorgegebenen Bremskraftverhältnis ermitteltes Bremsmoment (M) auf die zweite Fahrzeugachse (10) wirkt.5. The method of claim 4, wherein the second vehicle axle (10) associated friction brakes (4) assigned such be switched that a total of a situation dependent from a predetermined braking force ratio determined braking torque (M) acts on the second vehicle axle (10).
6. Verfahren nach einem der Ansprüche 1 bis 5, bei dem der Stellwert erst dann ausgegeben wird, wenn das insgesamt angeforderte Bremsmoment (M) einen vorgegebenen Grenzwert übersteigt .6. The method according to any one of claims 1 to 5, wherein the control value is output only when the total requested braking torque (M) exceeds a predetermined limit.
7. Bremssystem (1) für ein Kraftfahrzeug mit einer Anzahl von hydraulischen, elektronisch steuerbaren, jeweils einer Fahrzeugachse (8, 10) zugeordneten Reibbremsen (2, 4) und mit einem Generator (20), der kraftflussseitig mit einer ersten Fahrzeugachse (8) permanent und mit der anderen, zweiten Fahrzeugachse (10) über eine elektronisch ansteuerbare Allradkupplung (28) verbunden ist, die von einer Bremsensteuereinheit (14) mit einem Stellwert beaufschlagbar ist. 7. brake system (1) for a motor vehicle with a number of hydraulic, electronically controllable, in each case a vehicle axle (8, 10) associated friction brakes (2, 4) and with a generator (20) the power flow side with a first vehicle axle (8) permanently and with the other, second vehicle axle (10) via an electronically controllable four-wheel clutch (28) is connected, which is acted upon by a brake control unit (14) with a control value.
PCT/EP2006/065607 2005-09-01 2006-08-23 Method for controlling a brake system of a motor vehicle WO2007025926A1 (en)

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