DE102009011244A1 - Switching arrangement for operation of e.g. electromagnetic adjusting drive, in commercial vehicle, has control circuit controlling switch such that switch electrically and alternatively couples and decouples connections - Google Patents

Abstract

The arrangement (6) has a diode (D1) coupled electrically with a capacitor (C1) and an inductive load (2) by respective anode and cathode. Another diode (D2) is coupled electrically with an inductor (L2) and an electrical energy source (4) by respective anode and cathode. A switch (8) includes two connections, where the connections are coupled by the switch depending on a signal at a control input. A control circuit (10) controls the switch when a preset voltage is lowered such that the switch electrically and alternatively couples and decouples the connections.

Description

In Modern internal combustion engines often solenoid valves are used. A solenoid valve is a valve that is actuated by an electromagnet. There is also a very wide range of applications in automation technology for the Solenoid valves, for example in hydraulics and pneumatics.

One Use of modern valves, such as solenoid valves can be a very precise and also require fast switching. This requires a fast transmission of large quantities at electrical energy.

The The object underlying the invention is to provide a cost-effective circuit arrangement to create an inductive load fast and energy efficient can be operated.

The Task is solved by the characteristics of the independent Claims. Advantageous embodiments of the invention are specified in the subclaims.

According to one In the first aspect, the invention is characterized by a circuit arrangement for Operating an inductive load. The circuit comprises a first diode over their anode is electrically coupled to a capacitor and formed is over their cathode to be electrically coupled with an inductive load. A second diode is over its anode is electrically coupled to an inductor and adapted to be over its Cathode to be coupled with an electrical energy source. A switch comprises a control input, a first connection and a second connection. about the first terminal, the switch is electrically coupled to the Anode of the first electrode and over the second terminal, the switch is electrically coupled to the anode of the second diode. The switch is designed to dependent from a signal at the control input the first connection with the electrically couple second port. A drive circuit is electrically coupled to the control input of the switch and to formed, with a falling below a voltage applied to the capacitor predetermined voltage to control the switch such that the switch the first terminal to the second terminal alternately electrically coupled and decoupled.

This allows an energy-saving operation of the inductive load. Especially allows this an energy-saving removal of electrical energy from the inductive Load. The reason for that is that a big one Proportion of the electrical energy extracted from the inductive load can be returned to the electrical energy source. electrical Losses in the circuit can be kept low. This results in a low heat development in the circuit arrangement. Furthermore, the removal of electrical energy from the inductive Load done very quickly.

In a preferred embodiment The drive circuit comprises an oscillator for generating a oscillating signal of predetermined period, which is the switch when falling below the voltage applied to the capacitor predetermined Voltage is driving. this makes possible simply a fast discharge of the capacitor and thus the inductive Last, over the capacitor is discharged.

According to one another preferred embodiment the oscillator is designed as a tilt oscillator and comprises a Schmitt trigger or an inverting Schmitt trigger. This allows a simple realization of the drive circuit.

In a further preferred embodiment the drive circuit is designed to switch the switch so to trigger that a temporal relationship between an electric coupling state to an electrically decoupling state of the Switch regarding the first terminal or the second terminal in is about 1: 1. this makes possible a very simple control of the drive circuit, which is very inexpensive.

According to one another preferred embodiment the switch comprises a field effect transistor. This allows a simple design of the switch.

In a further preferred embodiment the storage choke comprises a core, which is designed as a pot core is. this makes possible the formation of a storage choke with a relatively large inductance, which allows fast unloading of the inductive load.

According to one another preferred embodiment the circuit arrangement is designed to operate an actuator a valve. this makes possible a fast control of an actuator of the valve by the Actuator.

According to a second aspect, the invention is characterized by an arrangement for operating a fluid system in an internal combustion engine. The arrangement comprises the circuit arrangement according to the first aspect. The valve includes an electromagnetic actuator as an inductive load. Valves in internal combustion engines often experience a very intensive use. This way, especially in the case of frequent activation over a relatively long period of time, making an energy-saving effect very noticeable. Furthermore, the very cost-effective design circuitry can quickly amortize, which can be particularly for the very cost-sensitive industries of production relation ship as the assembly of internal combustion engines and in automation technology very important.

embodiments The invention are explained in more detail below with reference to the schematic drawings.

It demonstrate:

1 a circuit arrangement with an electrical energy source and an inductive load,

2A to 2D the circuit arrangement with possible current curves,

3 Signal curves of an operating cycle of the inductive load,

4 a temporal excerpt of the signal courses,

5 further signal curves of the operating cycle of the inductive load,

6 the circuit arrangement, the electrical energy source and the inductive load in a detailed circuit diagram.

elements same construction or function are cross-figurative with the same Reference number marked.

1 shows an inductive load 2 , an electrical energy source 4 and a circuit arrangement 6 for operating the inductive load 2 , The inductive load 2 can be configured for example as an actuator of a valve. The valve may be, for example, a hydraulic valve or a pneumatic valve, which may be used, for example, in an internal combustion engine, for example, for operating a geared out as a transmission control hydraulic or pneumatic fluid system. The inductive load 2 However, it can also be designed differently. Conceivable is any possible known to those skilled in the art of electrical load, which has a substantially inductive character.

At the electrical energy source 4 it may be, for example, a voltage source. For example, the source of electrical energy may be 4 to act a battery, which is arranged for example in a commercial vehicle. The operating voltage of the electrical energy source 4 can be for example 30 volts. The electrical energy source 4 comprises in a preferred embodiment a first switching element S1 ( 6 ) so that a current flow resulting from the voltage can be switched on and off.

The circuit arrangement 6 comprises a first diode D1, which is electrically coupled to a capacitor C1 via its anode. Via its cathode, the first diode D1 is electrically coupled to both the electrical energy source 4 as well as with the inductive load 2 , The capacitor C1 is electrically coupled both to the anode of the first diode D1 and to a reference potential GND. The capacitor C1 can be referred to, for example, as a DC link capacitor. The anode of the first diode D1 and the capacitor C1 are further electrically coupled to a first terminal of a switch 8th as well as with an input of a drive circuit 10 ,

The drive circuit 10 has on the input side a further diode D3 ( 6 ) on. The further diode D3 ( 6 ) is formed, for example, as a ten-diode and is connected via its anode to both the anode of the first diode D1 and the capacitor C1 and to the first terminal of the switch 8th electrically coupled. The output side is the drive circuit 10 electrically coupled to a control input of the switch 8th , The desk 8th is designed to drive at Ansteu by the drive circuit 10 via its control input to electrically couple the first terminal to a second terminal.

A second diode D2 is electrically connected to the electrical energy source via its cathode 4 coupled. Via its anode, the second diode D2 is electrically coupled both to the second terminal of the switch 8th as well as with a storage choke 12 , The storage throttle 12 essentially comprises an inductance L2 (see 6 ) and is additionally electrically coupled to the reference potential GND.

The inductive load 2 is preferably formed unipolar. Single-pole loads have, in addition to an electrical coupling with the reference potential GND, another electrical connection. The further connection of the inductive load 2 is at a first potential V1 and is electrically coupled both to the cathode of the first diode D1 and to the source of electrical energy 6 ,

The circuit arrangement 6 is designed to be the inductive load 2 to take electrical energy through the first diode D1 and the capacitor C1 and the electrical energy source 4 over the storage throttle 12 and the second diode D2 too inflict. To accomplish this, is the drive circuit 10 by means of the further diode D3 ( 6 ) are designed such that when falling below a voltage applied to the capacitor C1 predetermined voltage, the switch 8th controls. The drive circuit 10 turns on the switch 8th when operating such that the switch 8th alternately electrically couples and decouples the first connection with the second connection. Based on 2A to 2D will the operation of the circuit 6 explained in more detail below:

2A shows an operating cycle of the inductive load 2 with a charging by the electrical energy source 6 starts. During the charging process, the inductive load 2 via the electrical energy source 4 and the circuit arrangement 6 initially supplied with electrical energy. In the event that the electrical energy source 6 the first switching element S1 ( 6 ), this is closed during the charging process. 2A shows the course of a current I1, that of the electrical energy source 4 through the inductive load 2 leads to the reference potential GND. When charging the inductive load 2 becomes dependent on a useful inductance L1 ( 6 ) induces a magnetic field which is a part of the electrically supplied energy in the inductive load 2 stores. In a training of the inductive load 2 as an actuator of the valve, the charging of the inductive load 2 lead to an opening of the valve. When the valve is fully open, it remains in this state, at least as long as the current I1 through the inductive load 2 flows.

To close the valve, the first switching element S1 ( 6 ) brought into an open position with the result that a current flow from the electrical energy source 6 is interrupted. This will start a discharge process. Subsequently, the inductive load 2 taken the stored energy. The faster the removal of the stored energy, the faster the valve closes or the faster the inductive load decreases 2 a state that is identical to an original state before the start of the charging process. A quick energy withdrawal is usually desirable.

The interruption of the flow of current from the electrical energy source 6 leads to a reduction of the inductive load 2 trained magnetic field. As a result, a voltage V1 is induced between the first potential V1 and the reference potential GND. The induced voltage V1 is the cause of in the 2 B drawn current I1. The Indian 2 B drawn current I1 runs during the discharge of the reference potential GND via the capacitor C1 and the first diode D1 and from there via the inductive load 2 to the reference potential GND. Between a second potential V2, on which the anode of the first diode D1 is located, and the reference potential GND, a negative voltage V2 is established, which is referred to below as the capacitor voltage V2. The capacitor C1 is electrically negatively charged. The charging process of the capacitor C1 becomes the inductive load 2 removed electrical energy and added to the capacitor C1. The capacitor voltage V2 decreases until it falls below the predetermined voltage.

The electrically coupled to the capacitor C1 further diode D3 ( 6 ) is designed such that it is low impedance when falling below the capacitor voltage V2 and is otherwise formed high impedance. As a result, decreases when the predetermined voltage between the second potential V2 and the reference potential GND, the drive circuit decreases 10 start operating and turn on the switch 8th alternately on and off such that the first terminal is periodically electrically coupled and decoupled with the second terminal. In a preferred embodiment, the alternating coupling and decoupling follows a predetermined period. In a further preferred embodiment, the ratio of a temporal extension between the assumption of the state in which the first terminal is electrically coupled to the second terminal to the state in which the first terminal is electrically decoupled from the second terminal is approximately 1: 1.

On from the state of electrical coupling of the switch 8th resulting current curve is in 2C shown. By the inductive load 2 continues to flow the current I1, which is continuously for a transfer of energy from the inductive load 2 into the capacitor C1 provides. The capacitor C1 is therefore still negatively charged by the current I1 via the first diode D1 and the inductive load 2. The resulting current flows from the reference potential GND through the SpeI cherdrossel 12 and the switch 8th via the capacitor C1 to the reference potential GND. The capacitor C1 is thereby taken energy and the storage choke 12 fed. In other words, the capacitor C1 becomes the closed switch 8th discharged. As a result, the capacitor voltage V2 again exceeds the predetermined voltage after a certain time of discharging and the further diode D3 (FIG. 6 ) behaves like a high-ohmic resistor again, so that the drive circuit 10 the switch 8th in the open state switches and in the following the switch 8th does not continue to drive.

As a result of the closed switch 8th and the resulting current through the storage choke 12 , is from the storage choke 12 a ma gnetfeld generated.

By opening the switch 8th the current flow is interrupted and the zuforderst in the storage throttle 12 generated magnetic field is degraded again, which in turn induces a voltage. The result is a pulse of the regenerative current I2, which from the reference potential GND via the storage inductor 12 and through the second diode D2 into the electric power source 4 flows. The source of electrical energy 4 In this way electrical energy is supplied.

In the in the 4 For example, two oscillator clocks occurred before the capacitor C1 was discharged so far that the oscillator circuit temporarily stopped.

The capacitor C1 is at the re-opened switch 8th via the inductive load 2 still negatively charged. At the capacitor C1, the capacitor voltage V2 decreases again or increases the amount of the capacitor voltage V2 again until it falls below the predetermined voltage again and the other diode D3 behaves again low impedance, resulting in a renewed activation of the switch 8th through the drive circuit 10 leads.

This process is repeated until the inductive load 2 is discharged, bringing the operating cycle of the inductive load 2 is finished and can be restarted, for example.

In the 3 For example, the waveforms of current I1, regenerative current I2 and capacitor voltage V2 are shown in milliseconds during one cycle of operation versus time. The rising edge of the current I1 corresponds to that in the 2A shown current flow. In other words, the rising edge of the current I1 corresponds to the charging of the inductive load 2 , The falling edge of the current I1 corresponds to the current characteristics of the 2 B . 2C and 2D , This is the unloading process. Characteristic of the regenerative current I2 is its pulse-shaped training.

A more detailed view shows the 4 , It is a temporal excerpt of the already in 3 illustrated unloading of the inductive load 2 , In the 4 Good to see is the pulsed regenerative current I2, which is always shortly after switching the switch 8th flows. Also clearly visible is the periodic curve of the capacitor voltage V2.

5 shows the waveforms of the current I1 and the voltage V1 of an operating cycle, the charging the discharge process of the inductive load 2 includes. The charging takes place between a time from T is about equal to -17 ms to a time of T = -5 ms. The charging takes place between the time of T = 5 ms and about T = 10 ms. Characteristic of the waveform of the current I1 are its two local maxima. The first local maximum explains a transition between the charging and discharging processes. The two te local maximum is a consequence of the impact of the actuator in a mechanical support of the valve.

6 shows a detailed circuit diagram with an equivalent circuit diagram for the inductive load 2 , An exemplary circuit diagram for the circuit arrangement 6 as well as the electrical energy source 4 ,

The inductive load 2 essentially comprises the working inductance L1. The useful inductance L1 can, for example, have the inductance 185 mH. Ohmic losses can be taken into account in the equivalent circuit by means of the first and the eleventh ohmic resistors R1 and R11. The first ohmic resistance Rl is characteristic of the iron losses of the inductive load 2 , The first ohmic resistance R1 may, for example, have 11.5 Ω. The eleventh ohmic resistor R11 may have, for example, 10 KΩ.

The in the circuit arrangement 6 shown storage choke 12 comprises a core in addition to an inductance L2 in a preferred embodiment 14 , which is designed as a pot core. The inductance L2 may be 50 μH, for example.

The drive circuit 10 In a preferred embodiment, on the input side, in addition to the further diode D3, a third ohmic resistor R3. The third ohmic resistor R3 has, for example, 10 KΩ.

In a preferred embodiment, the drive circuit 10 as in 6 shown formed as an oscillator circuit. The in the 6 shown oscillator circuit generates a square wave signal during operation. In a preferred embodiment, the drive circuit 10 as in 6 shown formed as an oscillator circuit. The drive circuit is preferred 10 formed as a circuit of discrete components. This allows a very cost-effective drive circuit 10 , The drive circuit 10 However, it can also be designed differently. For example, the drive circuit 10 Also include a microcontroller, for example, by appropriate programming the control of the switch 8th pretends. A control of the switch 8th via its control input can then be made such that both the times in which the switch 8th is switched as well as the temporal relationship of the two states by the programming of the microcontroller can be arbitrarily specified. The efficiency of the circuit arrangement 6 is significantly influenced by the way the switch 8th is controlled.

Empirical studies have shown that the circuitry 6 in the form of an oscillator circuit drive circuit 10 as they are in 6 shown has an efficiency of about 90%.

The drive circuit designed as an oscillator circuit preferably comprises 10 an inverting Schmitt trigger 74HC14. On the input side, the inverting Schmitt trigger 74HC14 is electrically coupled to the collector of a third switching element S3 designed, for example, as an npn bipolar transistor, and also having a second capacitor C2 and a fourth ohmic resistor R4. The second capacitor C2 may, for example, have a size of 470 pF. The fourth ohmic resistor R4 may have, for example, 33 KΩ. A dimensioning of the second capacitor C2 and the fourth ohmic resistor R4 significantly influences the time ratio in which the switch 8th is in a closed position or an open position. This arrangement of the inverting Schmitt trigger (74HC14) together with the fourth ohmic resistor R4 and the second capacitor C2 may also be referred to as a tilt oscillator.

In the embodiment of the third switching element S3 as npn bipolar transistor, the base is electrically coupled both to the cathode of the further diode D3 via the third ohmic resistor R3, as well as to a third capacitor C3 and to an eighth ohmic resistor R8. The third capacitor C3 is, for example, 220 pF and is primarily used for an advantageous electromagnetic compatibility of the drive circuit 10 , The eighth ohmic resistor R8 comprises, for example, 10 KΩ. The eighth ohmic resistor R8 serves as a voltage divider and is further electrically coupled both to a supply terminal of a fourth switching element S4 and to a source potential V3 of a voltage source. The voltage at the source potential V3 may be, for example, 5 volts. The emitter of the third switching element S3 is electrically coupled to the reference potential GND.

On the output side For example, the inverting Schmitt trigger 74HC14 is electrically coupled via resistive base resistors R5a and R5b having the base of, for example, a pnp bipolar transistor fourth switching element S4.

In the event that the capacitor voltage V2 does not fall below the predetermined voltage, the further diode D3 is formed high impedance, resulting in that the third switch S3 is closed and the inverting Schmitt trigger 74HC14 on the input side via the third switch S3 to the reference potential GND is applied. As a result, a positive voltage is applied to the output side of the inverting Schmitt trigger 74HC14, so that the fourth switching element S4 is open. By formed as a voltage divider sixth and seventh ohmic resistance R6 and R7, which may be, for example, 2.2 KΩ and 3.3 KΩ and are electrically coupled to the gate of a formed example as a field effect transistor second switching element S2, there is the switch 8th when not driven by the drive circuit 10 in an open position. If the capacitor voltage V2 exceeds the value of the predetermined voltage, then the further diode D3 becomes low-impedance. This causes the third switching element S3 opens. By the output side of the inverting Schmitt trigger 74HC14 then applied positive voltage and designed as a voltage divider fourth resistor R4, the second capacitor C2 is charged until a voltage applied to the input side of the inverting Schmitt trigger 74HC14 voltage for the inverting Schmitt trigger Exceeds 74HC14 characteristic threshold. As a result, the inverting Schmitt trigger 74HC14 outputs again a negative voltage level on the output side. The fourth switching element S4 then closes, which at the gate of the second switching element S2 results in a positive voltage level and the switch 8th thus switches to a closed position in which the first terminal is electrically coupled to the second terminal.

The electrical energy source 4 can be operated, for example, at a voltage level of 30 volts. This corresponds to an operating voltage for which vehicle systems of commercial vehicles are frequently designed today.

2

inductive load

4

electrical energy

6

circuitry

8th

switch

10

drive circuit

12

Power inductor

14

core

C1

capacitor

C2

second capacitor

C3

third capacitor

D1

first diode

D2

second diode

D3

Further diode

L1

Nutzinduktivität

L2

inductance

R1

first ohmic resistance

R2

second ohmic resistance

R3

third ohmic resistance

R4

fourth ohmic resistance

5a, b

base resistors

R6

sixth ohmic resistance

R7

seventh ohmic resistance

R8

eight ohmic resistance

I1

electricity

I2

Feedback current

V1

tension between first potential V1 and GND

V2

capacitor voltage between 2nd potential and GND

V3

source potential

S1

first switching element

S2

second switching element

S3

third switching element

S4

fourth switching element

74HC14

inverting Schmitt trigger

Claims (8)

Circuit arrangement for operating an inductive load ( 2 ), comprising a first diode (D1) which is electrically coupled via its anode to a capacitor (C1) and which is formed via its cathode with the inductive load (D1). 2 ) to be electrically coupled, - a second diode (D2), which is electrically coupled via its anode to an inductance (L2) and is formed via its cathode with an electrical energy source ( 4 ), - a switch ( 8th ) - having a control input, a first terminal and a second terminal, - is electrically coupled via the first terminal to the anode of the first diode (D1), - is electrically coupled via the second terminal to the anode of the second diode (D2 ), - is designed to electrically couple the first terminal to the second terminal depending on a signal at the control input, - a control circuit ( 10 ) electrically connected to the control input of the switch ( 8th ) is coupled and is formed at a below a voltage applied to the capacitor (C1) predetermined voltage, the switch ( 8th ) such that the switch ( 8th ) alternately electrically couples and decouples the first terminal with the second terminal. Circuit arrangement according to Claim 1, in which the drive circuit ( 10 ) comprises an oscillator for generating an oscillating signal having a predetermined period, the switch ( 8th ) drives at a below the voltage applied to the capacitor (C1) predetermined voltage. Circuit arrangement according to Claim 2, in which the Oscillator is designed as a tilt oscillator and a Schmitt trigger or a inverting Schmitt trigger (74HC14). Circuit arrangement according to one of the preceding claims, in which the drive circuit ( 10 ) is designed to switch ( 8th ) such that a time relationship between an electrically coupling state to an electrically decoupling state of the switch ( 8th ) is about 1: 1 with respect to the first terminal and the second terminal, respectively. Circuit arrangement according to one of the preceding claims, in which the switch ( 8th ) comprises a field effect transistor (S2). Circuit arrangement according to one of the preceding claims, in which the storage choke comprises a core ( 14 ), which is designed as a pot core. Circuit arrangement according to one of the preceding claims, in the circuit arrangement is designed to operate a Actuator of a valve. Arrangement for operating a fluid system in an internal combustion engine, having - a circuit arrangement according to one of the preceding claims, - a valve serving as the inductive load ( 2 ) comprises an electromagnetic actuator.