WO2016001281A1

WO2016001281A1 - Internal combustion engine

Info

Publication number: WO2016001281A1
Application number: PCT/EP2015/064939
Authority: WO
Inventors: Sebastian EWERT; Sascha NAUJOKS
Original assignee: Mahle International Gmbh
Priority date: 2014-07-04
Filing date: 2015-07-01
Publication date: 2016-01-07
Also published as: DE102014213070A1

Abstract

The present invention relates to an internal combustion engine (1), in particular of a motor vehicle, comprising an engine block (2) which has multiple cylinders (3) which each contain a combustion chamber (4), comprising a fresh-air system (6) for the supply of fresh air to the combustion chamber (4), comprising an exhaust system (8) for the discharge of exhaust gas from the combustion chambers (4), comprising an exhaust-gas turbocharger (10), the turbine (11) of which is arranged in the exhaust system (8) and the compressor (12) of which is arranged in the fresh-air system (6), and comprising an exhaust-gas aftertreatment system (16) which is arranged in the exhaust system (8) and which has at least one exhaust-gas aftertreatment device (17) arranged upstream of the turbine (11). Improved response behaviour is realized by way of an electrically driven machine (18) for increasing the charge pressure in the fresh-air system (6).

Description

Internal combustion engine

The present invention relates to an internal combustion engine, in particular of a motor vehicle, having the features of the preamble of claim 1.

From DE 10 2007 032 736 A1 an internal combustion engine is known which comprises an engine block, a fresh air system, an exhaust system, an exhaust gas turbocharger and an exhaust aftertreatment system. The engine block has a plurality of cylinders, each containing a combustion chamber. The fresh air system is used to supply fresh air to the combustion chambers. The exhaust system serves to discharge exhaust gas from the combustion chambers. A turbine of the exhaust gas turbocharger is arranged in the exhaust system, while a compressor of the exhaust gas turbocharger is arranged in the fresh air system. The exhaust aftertreatment system is arranged in the exhaust system and has at least one exhaust aftertreatment device arranged upstream of the turbine.

The turbine extracts energy from the exhaust gas, which is used in the exhaust gas turbocharger to drive the compressor. In this case, the exhaust gas not only kinetic energy resulting from the exhaust gas mass flow, and potential energy resulting from the exhaust pressure, withdrawn, but also thermal energy resulting from heat capacity, mass and temperature of the exhaust gas. Thus, in particular, the exhaust gas temperature decreases during the flow through the turbine.

Certain exhaust aftertreatment devices, such as catalysts, require a certain minimum operating temperature in order to perform their intended cleaning task. When cold starting the engine is In order to comply with strict emission regulations, it is necessary to reach this minimum heating temperature as quickly as possible. Furthermore, with efficient internal combustion engines in the partial load range, the exhaust gas may have a relatively low exhaust gas temperature which is only slightly above the required minimum operating temperature. In a supercharged internal combustion engine - as shown above - the turbine leads to a reduction of the exhaust gas temperature, whereby the heating of the respective exhaust gas after-treatment device is delayed in a cold start, whereby the pollutant emissions of the internal combustion engine can increase. Furthermore, with an efficient internal combustion engine at partial load, the turbine can lead to the exhaust gas temperature downstream of the turbine being able to drop below the minimum operating temperature of the respective exhaust gas aftertreatment device. Accordingly, it is provided in the generic internal combustion engine to arrange at least one such exhaust aftertreatment device upstream of the turbine, whereby the above-mentioned problems are largely solved.

However, the arrangement of at least one exhaust aftertreatment device upstream of the turbine has the consequence that the flow through such an exhaust aftertreatment device inevitably goes hand in hand with a pressure drop in the exhaust gas flow, which leads to a significant power loss in the subsequent turbine. This has a particularly significant effect in a transient operating state, in which a speed and / or load of the internal combustion engine increases or increases. In this case, the turbine can increase its power only delayed, since only a reduced exhaust gas pressure is available. In this way, a so-called "turbo lag" is formed or increased, which corresponds to a delayed response of the turbocharger in the aforementioned transient operating conditions. The speed of the internal combustion engine corresponds to a speed of a crankshaft of the engine block, which is driven by pistons of the engine block, including the piston in the cylinders of the engine block hub-. are arranged adjustable. The load of the internal combustion engine is a torque which is provided or can be tapped off on the crankshaft.

The present invention is concerned with the problem of providing an improved embodiment for an internal combustion engine of the aforementioned type, which is characterized in particular by the fact that an improved response of the exhaust gas turbocharger can be achieved under transient conditions.

This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of equipping the internal combustion engine with an electrically driven machine with the aid of which the boost pressure in the fresh air system can be increased as needed. The invention assumes that it is sufficient to reduce or to bridge the turbo lag, temporarily increase the boost pressure until the turbine itself can generate sufficient power to generate the desired, increased boost pressure itself via the compressor. The use of an electrically driven machine can be implemented particularly easily. In particular, such a machine can be switched on and off particularly easily according to demand.

According to an advantageous embodiment, a controller for controlling the machine may be provided, which is designed or programmed to temporarily switch on the machine when there is a transient state of the internal combustion engine in which a speed and / or load of the internal combustion engine increases or increase. By this measure, the respective machine is always only turned on or activated, if due the transient state an increased boost pressure is needed. Thus, this measure works to increase performance particularly efficient.

The control device is thus ultimately designed or programmed so that it can perform a method for operating the internal combustion engine. This operating method provides for temporarily switching on the respective machine in the event of a transient state of the internal combustion engine.

According to a development, the controller may be configured or programmed such that it determines a switch-on time duration and / or a power of the machine with which the controller controls the machine in the transient state, depending on a speed difference and / or depending on a load difference is given by a comparison of an actual state of the internal combustion engine with a desired state of the internal combustion engine or yield, wherein the actual state of the internal combustion engine before the transient state or at the beginning thereof, while the target state of the internal combustion engine after the transient State or at the end should be present. The controller can thus not only turn the respective machine on and off, but also specifically with regard to the switch-on and additionally or alternatively targeted targeted in terms of performance. Thus, the operation of the machine can be specifically tuned to the respective transient state to largely eliminate the effect of the turbo lag. The control device can, for example, access characteristic maps or calculation models for determining the switch-on duration or the power.

In an advantageous development, the control device can be configured or programmed such that it always controls the machine in the transient state with the same electrical power, while a switch-on period is variable and in particular from the desired target state or from the (the) dependent difference (s). This results in a particularly simple control of the machine.

According to an advantageous embodiment, the machine may be an electric motor driven auxiliary compressor, which is arranged in the fresh air system. This additional compressor is additionally and separately arranged to the compressor of the exhaust gas turbocharger in the fresh air system, wherein the additional compressor with respect to the flow direction of the fresh air upstream or downstream of the compressor can be arranged. With the help of the additional compressor, the desired boost pressure can be built up particularly efficiently.

According to an advantageous development, the fresh air system may have a bypass for bypassing the additional compressor. The auxiliary compressor, in the event that it is not needed and accordingly switched off, a flow resistance for the fresh air flow. By the bypass, the fresh air flow can bypass the auxiliary compressor with reduced flow resistance. Appropriately, a bypass valve for controlling the bypass may be arranged in the bypass. In particular, the bypass can be blocked and opened with the help of the bypass valve. When the bypass is locked or closed, the air flow is routed through the auxiliary compressor. When the bypass is open, the fresh air automatically flows largely through the bypass when the additional compressor is switched off, which has a considerably smaller flow resistance in comparison to the additional compressor. Appropriately, the bypass begins immediately before the additional compressor. Furthermore, it can be provided that the bypass ends immediately after the additional compressor. Thus results for the additional compressor with bypass an extremely compact design.

In another advantageous development, the control device can be configured or programmed in such a way that when the additional device is switched on. dichters the bypass valve to block the bypass controls. Furthermore, the control device expediently with the switching off of the additional compressor driving the bypass valve to open the bypass. This ensures that the bypass is closed only when the booster compressor is switched on, while the bypass is always open when the booster compressor is switched off.

In another advantageous development, a charge air cooler can be arranged in the fresh air system downstream of the compressor and downstream of the additional compressor. The additional compressor can be arranged downstream or upstream of the compressor. The proposed arrangement of the intercooler can be both the associated with the compression in the compressor temperature increase in the charge air and compensate for the additional compression in the additional compressor additional temperature increase in the charge air, on the one hand to increase the air mass flow and on the other hand, the pollutant emissions of the engine to reduce.

In an alternative development of the additional compressor can be arranged downstream of the compressor in the fresh air system, wherein a charge air cooler is arranged in the fresh air system downstream of the compressor and upstream of the additional compressor. In this design, therefore, only the temperature increase in the charge air due to the compression in the compressor is compensated. This embodiment is based on the consideration that the transient states in which the auxiliary compressor is activated, only a small proportion in relation to the total operating time of the internal combustion engine, so that the short-term increased charge air temperature can have only a small effect. However, the positioning of the additional compressor downstream of the intercooler has the advantage that increased flexibility for the integration of the additional compressor in the fresh air system arises. According to another embodiment, the engine may be an electromotive drive of the exhaust gas turbocharger drivingly connected to a drive shaft drivingly connecting a turbine wheel of the turbine to a compressor wheel of the compressor. Usually turbine wheel and compressor have a common drive shaft to which they are mounted rotationally fixed and which is mounted in the housing of the exhaust gas turbocharger. The housing of the exhaust gas turbocharger usually comprises three sections, namely a turbine section, in which the turbine wheel is rotatably arranged, a compressor section, in which the compressor wheel is rotatably arranged, and a bearing section, which is arranged between the turbine section and the compressor section, and in which the drive shaft is rotatably mounted. The electromotive drive can now basically be drive-connected at any point with this drive shaft of the exhaust gas turbocharger. For example, the drive may be connected to the drive shaft through the turbine housing or through the compressor housing. In this case, a rotational axis of the drive may be aligned parallel to the axis of rotation of the drive shaft. It is also conceivable to couple the drive in the region of the bearing section with the drive shaft, wherein then a rotational axis of the drive inclined, in particular perpendicular, can extend to the axis of rotation of the drive shaft.

Particularly advantageous is an embodiment in which the drive is integrated in a housing of the exhaust gas turbocharger. Such an integration between the turbine wheel and the compressor wheel, preferably in the area of the bearing section, can be implemented particularly expediently. For example, the drive can be integrated in the bearing section.

In another development, the drive can be connected via a clutch and / or via a transmission with the drive shaft. Through the clutch or Through the transmission, the spatial orientation of the axis of rotation of the drive can be aligned almost arbitrarily to the spatial position of the axis of rotation of the drive shaft. This simplifies the drive coupling between the drive and drive shaft. The use of a transmission in particular allows a ratio between the speed of the drive and the speed of the drive shaft. In a sufficiently powerful drive while a translation is preferred to fast to realize high speeds for the drive shaft. The use of a controllable clutch allows a demand-dependent connection or engagement and disengagement or disconnection of the drive with the drive shaft.

According to an advantageous embodiment, the at least one exhaust aftertreatment device arranged upstream of the turbine can be a three-way catalyst or an oxidation catalyst or an SCR catalyst, where SCR stands for Selective Catalyst Reduction, or an LNT catalyst, where LNT stands for Lean NO _x Trap , or a particulate filter or any combination of the above elements. Such a combination is, for example, an oxidation catalyst upstream of a particulate filter in a common housing. Further, optionally, an SCR catalyst may be disposed downstream of the particulate filter in the same housing. Particularly compact are combinations in which an oxidation catalyst is arranged in the same housing and downstream of a particle filter, wherein the particle filter is provided with an SCR catalyst coating.

According to another advantageous embodiment, it can be provided that all exhaust aftertreatment devices of the exhaust aftertreatment system are arranged upstream of the turbine in the exhaust system. Thus, the exhaust aftertreatment system can be completely in the hot area of the exhaust system, ie upstream of the turbine order. Other components of the exhaust system, which do not require a minimum operating temperature, such as mufflers, are then located downstream of the turbine in the exhaust system.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

1 to 3 each show a greatly simplified, schematic diagram of a schematic diagram of an internal combustion engine in a first embodiment in three different variants,

Fig. 4 is a greatly simplified schematic diagram of the principle

Internal combustion engine in a second embodiment.

According to FIGS. 1 to 4, an internal combustion engine 1, which can be used in particular in a motor vehicle, comprises an engine block 2 which contains a plurality of cylinders 3, in each of which a combustion chamber 4 is formed. In the cylinders 3 also not shown piston are arranged adjustable stroke, which are connected in the usual way via connecting rods with a crankshaft 5 of the engine block 2. The internal combustion engine 1 further comprises a fresh air system 6 for supplying fresh air to the combustion chambers 4. A corresponding fresh air flow 7 is indicated by arrows. The internal combustion engine 1 also has an exhaust system 8, which serves for discharging exhaust gas from the combustion chambers 4. A corresponding exhaust stream 9 is indicated by arrows.

The internal combustion engine 1 is charged and is accordingly equipped with an exhaust gas turbocharger 10, which in the usual way a turbine 1 1, which is arranged in the exhaust system 8, and a compressor 12, which is arranged in the fresh air system 6. The turbine 1 1 comprises a turbine wheel 13, which is driven by the exhaust gas flow 9. The compressor 12 includes a compressor wheel 14 which drives the air flow 7. A drive shaft 15 of the exhaust gas turbocharger 10, which can also be referred to below as the turbocharger 10, connects the turbine wheel 13 to the compressor wheel 14.

The internal combustion engine 1 further comprises an exhaust aftertreatment system 16, which is arranged in the exhaust system 8 and which has at least one exhaust gas aftertreatment device 17, which is arranged upstream of the turbine 1 1 with respect to the flow direction of the exhaust gas flow 9.

The internal combustion engine 1 presented here is also equipped with an electrically driven machine 18, with the help of which the boost pressure in the fresh air system 6 can be increased as needed. For controlling this machine 18, a control device 19 is provided, which can be electrically connected to the machine 18 in a suitable manner, for example via at least one control line 20. The control device 19 can be used, for example, via at least one signal line 21 to be electrically connected to an engine control unit 22, which is provided for driving the internal combustion engine 1. For this purpose, the engine control unit 22 is purely exemplary connected via at least one line 23 to the engine block 2. The control device 19 for controlling the machine 18 is preferably integrated into the engine control unit 22 in terms of hardware and / or implemented in the engine control unit 22 by software. In any case, the control device 19, for example via the signal line 21, knows the current operating state of the internal combustion engine 1. The control device 19 may in particular also identify a transient state of the internal combustion engine 1, in which a rotational speed of the internal combustion engine 1 increases and / or in which a load of the internal combustion engine 1 increases. The control device 19 is designed or programmed so that it temporarily turns on the machine 18 in the presence of such a transient state. In this case, the control device 19 can optionally be configured or programmed such that it determines a switch-on time duration and / or a power of the machine 18 with which the control device 19 controls the machine 18 in the transient state, depending on a speed difference or a load difference , The speed difference or the load difference results from a comparison of an actual state of the internal combustion engine 1 with a desired state of the internal combustion engine. The actual state is present immediately before the transient state, while the desired state should be present immediately after the transient state. The control device 19 can now determine depending on the detected difference, for example via maps and / or calculation models, each required on-time or the respective required power of the machine 18 and control the machine 18 accordingly.

In a particularly simple embodiment, the control device 19, the machine 18 in the transient state always with the same electrical power while a turn-on time is variable and depends on the determined difference in speed and / or load.

In the examples of FIGS. 1 to 3, which relate to a first embodiment in different variants, the machine 18 is an electric motor driven auxiliary compressor 24, which is arranged in addition to the compressor 12 in the fresh air system 6. In the examples shown, the auxiliary compressor 24 accepts a compressor unit 25, which is arranged in the fresh air system 6 and which serves for driving or compressing the fresh air. The compressor unit 25 includes, for example, a corresponding compressor wheel. Further, the booster compressor 24 includes a drive unit 26, e.g. in the form of an electric motor to drive the compressor unit 25.

In the embodiments of FIGS. 1 to 3, the fresh air system 6 is also equipped with a bypass 27 for bypassing the auxiliary compressor 24. In the bypass 27, a bypass valve 28 for controlling the bypass 27 is arranged. The controller 19 communicates, e.g. via a control line 29, with the bypass valve 28, so that the control device 19, the bypass valve 28 to open and close the bypass 27 can control. The control device 19 is expediently configured in such a way that it activates the bypass valve 28 for blocking the bypass 27 when the auxiliary compressor 24 is switched on. With the switching off of the additional compressor 24, the control device 19 then controls the bypass valve 28 to open the bypass 27.

1 to 4, a charge air cooler 30 is also arranged in the fresh air system 6, which is coupled heat transfer in a conventional manner with a cooling circuit not shown here and which is arranged downstream of the compressor 12 with respect to the flow direction of the fresh air stream. In FIGS. 1 and 2, the intercooler 30 is disposed both downstream of the compressor 12 and downstream of the booster compressor 24 in the fresh air system 6. In the embodiment shown in FIG. 1, the additional compressor 24 is arranged upstream of the compressor 12 in the fresh air system 6. It is noteworthy that the bypass 27 has an inlet end 31 arranged immediately upstream of the auxiliary compressor 24 and an outlet end 32 arranged immediately downstream of the auxiliary compressor 24, the outlet end 32 being connected to the fresh air system 6 upstream of the compressor 12.

In the embodiment shown in FIG. 2, the additional compressor 24 is arranged downstream of the compressor 12 in the fresh air system 6. It is noteworthy that here the inlet end 31 of the bypass 27 is arranged between the compressor 12 and the auxiliary compressor 24, while the outlet end 32 of the bypass 27 is arranged between the auxiliary compressor 24 and the charge air cooler 30.

In the embodiment shown in FIG. 3, the additional compressor 24 is again arranged downstream of the compressor 12 in the fresh air system 6. In this variant, however, the charge air cooler 30 is arranged upstream of the auxiliary compressor 24 and downstream of the compressor 12 in the fresh air system 6. Accordingly, the charge air cooler 30 is positioned between the compressor 12 and the booster compressor 24. The inlet end 31 of the bypass 27 is connected between the intercooler 30 and the additional compressor 24 to the fresh air system 6. The outlet end 32 of the bypass 27 is connected between the auxiliary compressor 24 and the engine block 20 to the fresh air system 6.

In the second embodiment shown in Fig. 4, the machine 18, by means of which the boost pressure can be increased as needed in a transient state of the internal combustion engine 1, formed by an electric motor drive 33 of the turbocharger 10, which in a suitable manner with the drive shaft 15th is drive connected. Suitably, the drive 33, which is preferably formed by an electric motor or at least comprises an electric motor, be integrated into a not shown here housing of the turbocharger 10. The drive 33 may be connected via a coupling 34 and / or via a gear 35 to the drive shaft 15. In the example of FIG. 4, both a clutch 34 and a transmission 35 are provided purely by way of example. About the clutch 34, the drive 33 can switch on demand and completely decouple when it is not needed. Via the gear 35, a speed difference between the drive 33 and the drive shaft 15 can be generated. In the example of FIG. 4, a rotation axis 37 of the drive 33 is oriented substantially perpendicular to a rotation axis 38 of the drive shaft 15.

If such a switchable clutch 34 is provided, the control device 19 may be electrically connected to the clutch 34 via a corresponding control line 36, so that the control device 19 can actuate the clutch 34 for engaging and disengaging, appropriately in synchronism with the switching on and off of the drive 33rd

The exhaust aftertreatment device 17 arranged upstream of the turbine 11 may be, for example, a three-way catalytic converter or an oxidation catalytic converter or an SCR catalytic converter or an LNT catalytic converter or a particle filter. Also conceivable is a combination of the aforementioned facilities. For example, the exhaust gas aftertreatment device 17 may contain in a common housing a combination of an oxidation catalyst and a downstream particulate filter and a downstream SCR catalyst, wherein the SCR catalyst may be formed in particular by a catalytically active coating of the particulate filter. It may expediently be provided in a particularly advantageous embodiment that all exhaust aftertreatment devices 17 of the exhaust aftertreatment system 16 are arranged upstream of the turbine 1 1 in the exhaust system 8. Thus, the entire pollutant cleaning of the exhaust stream 9 upstream of the turbine 1 takes place 1. Sound-absorbing measures, in particular in the form of mufflers, however, can preferably be arranged downstream of the turbine 1 1 in the exhaust system 8.

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Claims

claims

1 . Internal combustion engine, in particular of a motor vehicle,

- With an engine block (2) having a plurality of cylinders (3), each containing a combustion chamber (4),

- With a fresh air system (6) for supplying fresh air to the combustion chambers (4),

with an exhaust system (8) for discharging exhaust gas from the combustion chambers (4),

- With an exhaust gas turbocharger (10) whose turbine (1 1) in the exhaust system (8) is arranged and the compressor (12) in the fresh air system (6) is arranged,

with an exhaust aftertreatment system (16) arranged in the exhaust system (8), which has at least one exhaust gas aftertreatment device (17) arranged upstream of the turbine (11),

characterized by an electrically driven machine (18) for increasing the boost pressure in the fresh air system (6).

2. Internal combustion engine according to claim 1,

characterized by a control device (19) for activating the machine (18), which is designed and / or programmed such that, in the event of a transient state of the internal combustion engine (1) during which a rotational speed and / or a load of the internal combustion engine ( 1) increases / increases, the machine (18) temporarily turns on to increase the boost pressure.

3. Internal combustion engine according to claim 2, characterized,

in that the control device (19) is designed and / or programmed such that it controls a switch-on time duration and / or a power of the machine (18) with which it activates the machine (18) in the transient state, depending on a speed difference and / or a Determined load difference, which results from a comparison of an actual state of the internal combustion engine (1), which is present before the transient state, with a desired state of the internal combustion engine (1), which should be present after the transient state.

4. Internal combustion engine according to claim 2 or 3,

characterized,

in that the control device (19) is designed and / or programmed to always drive the machine (18) in the transient state with the same electrical power while a switch-on period of time is variable.

5. Internal combustion engine according to one of claims 1 to 4,

characterized,

the machine (18) is an electric motor driven auxiliary compressor (24) arranged in the fresh air system (6).

6. Internal combustion engine according to claim 5,

characterized,

the fresh air system (6) has a bypass (27) for bypassing the additional compressor (24), in which a bypass valve (28) for controlling the bypass (27) is arranged.

7. Internal combustion engine according to claims 2 and 6,

characterized, in that the control device (19) is designed and / or programmed so that it activates the bypass valve (28) for blocking the bypass (27) when the additional compressor (24) is switched on.

8. Internal combustion engine according to one of claims 5 to 7,

characterized,

a charge air cooler (30) is arranged in the fresh air system (6) downstream of the compressor (12) and downstream of the additional compressor (24).

9. Internal combustion engine according to one of claims 5 to 7,

characterized,

- That the additional compressor (24) downstream of the compressor (12) in the fresh air system (6) is arranged,

- That a charge air cooler (30) in the fresh air system (6) downstream of the compressor (12) and upstream of the additional compressor (24) is arranged.

10. Internal combustion engine according to one of claims 1 to 4,

characterized,

in that the machine (18) is an electromotive drive (33) of the exhaust-gas turbocharger (10) which is drive-connected to a drive shaft (15) which has a turbine wheel (13) of the turbine (11) with a compressor wheel (14) of the compressor (14). 12).

1 1. Internal combustion engine according to claim 10,

characterized,

the drive (33) is integrated in a housing of the exhaust-gas turbocharger (10).

12. Internal combustion engine according to claim 10 or 1 1,

characterized, the drive (33) is connected to the drive shaft (15) via a coupling (34) and / or a gear (35).

13. Internal combustion engine according to any one of claims 1 to 12,

characterized,

in that the exhaust gas aftertreatment device (17) arranged at least one upstream of the turbine (11) is a three-way catalytic converter or an oxidation catalytic converter or an SCR catalytic converter or an LNT catalytic converter or a particle filter or any combination thereof.

14. Internal combustion engine according to one of claims 1 to 13,

characterized,

in that all exhaust aftertreatment devices (17) of the exhaust aftertreatment system (16) are arranged upstream of the turbine (11) in the exhaust system (8).

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