DE102013220340A1 - Device for controlling a hydraulically actuated clutch - Google Patents

Abstract

The invention relates to a device for controlling a hydraulically actuated clutch (34) of a motor vehicle, which is equipped with a slip control system acting on the actuation of a plurality of hydraulic wheel brakes (22a, 22b), wherein a pressure source (32, 42) of the slip control system is coupled via a first control valve (36) with a hydraulic disengaging unit of the clutch (34). The invention is characterized in that the pressure source coupled to the disengagement unit of the clutch is designed as an active pressure source (32, 42) by means of which a pressure required to disengage the clutch (34) can be generated according to a current disengagement request.

Description

The invention relates to a device for controlling a hydraulically actuated clutch of a motor vehicle, which is equipped with an acting on the actuation of a plurality of hydraulic wheel slip control system, wherein a pressure source of the slip control system is coupled via a first control valve with a hydraulic disengaging unit of the clutch.

Such devices are known from the DE 195 38 974 A1 ,

Modern motor vehicles are regularly equipped with a slip control system which performs the functions of an anti-lock braking system (ABS) or typically the functions of the anti-lock braking system (ABS) and an electronic stability program (ESP) or an Electronic Stability Control (ESC ) united. The mechanical / hydraulic part of such a slip control system is interposed between the master cylinder and the wheel brakes. It comprises at least one internal pressure source and a set of control valves, which are controlled in part by a suitably established control device in a regulated manner. As part of the ESP can thereby be controlled independently of a brake pedal actuation individual wheel brakes, wherein the brake pressure required for this purpose comes from said internal pressure source. As part of the possibly additionally existing ABS, individual wheel brakes can be specifically relieved during the braking process. In the system disclosed in the aforementioned document, the master brake cylinder is preceded by an external high-pressure accumulator, the pressure of which is used to boost the brake pressure generated by the brake pedal actuation. This high-pressure accumulator is coupled via a first control valve with a hydraulic clutch-disengaging unit, in particular the hydraulic slave cylinder of a hydraulically actuated clutch. In this way, the clutch can be actuated automatically, wherein the clutch system and the brake / slip control system are formed as two branches of the same hydraulic system. A disadvantage of the known device is the need to keep the high-pressure accumulator always charged, which leads to the energy-intensive operation of a corresponding high-pressure pump permanently or at the latest after each braking or coupling process.

It is the object of the present invention to develop a generic device for controlling a hydraulically actuated clutch in such a way that the overall system can be implemented in a space-saving and energy-efficient manner.

This object is achieved in conjunction with the features of the preamble of claim 1, characterized in that the pressure source coupled to the disengagement unit of the clutch is formed as an active pressure source, by means of which a pressure required to disengage the clutch can be generated according to a current disengagement request.

Preferred embodiments of the invention are the subject of the dependent claims.

The basic idea of the invention is to use an internal pressure source of the slip control system instead of an external high-pressure accumulator for driving the clutch. These pressure sources are typically used as active pressure sources, i. not as a memory. Rather, they are provided with a motor drive, which can be controlled as needed (power on demand). This means that the required for the clutch actuation pressure is only generated and only to the extent required for a currently requested clutch operation. An inefficient provision of a high pressure in a passive pressure accumulator is not required. Accordingly, it can be dispensed with such a pressure accumulator or it can, if it is indispensable for other reasons, be dimensioned correspondingly smaller, which is advantageous in terms of the required space and resulting with a larger dimensioning or design for higher pressures leakage problems. By contrast, the active, internal pressure sources are an indispensable component of the slip control system anyway, so that their use according to the invention as a pressure source for the clutch actuation does not entail additional structural complexity. In addition, no significant larger interpretation of the internal pressure source of the slip control system is required because the vast majority of the clutch operations to be controlled in the typically very broad periods of inactivity, namely, if no actual slip control is required, the internal pressure sources will fall. The design of the internal pressure sources merely has to ensure that, exceptionally, a pressure required for clutch actuation and simultaneous, corrective brake actuation can be generated.

Which unit of a slip control system is used concretely in accordance with the invention as a pressure source for the clutch actuation depends primarily on the specific design of the slip control system.

Typical slip control systems have as internal pressure source to a so-called return pump, which is capable of depending on the switching position of a set of typically four control valves per wheel brake, hydraulic fluid from a suck in the central reservoir and pressurize the slave cylinder of the corresponding wheel brake with pressure. For this embodiment of the slip control system, the invention provides that the disengagement unit of the clutch via the first control valve, hereinafter also referred to as a clutch inlet valve, with the pressure side of a return pump of the slip control system, preferably configured as a variable speed pump, particularly preferably designed as a multi-piston pump coupled.

Another variant of slip control systems is known as a plunger variant. As internal pressure sources, these systems have a motor-bi-directionally adjustable piston which delimits a fluid space filled with hydraulic fluid and connected to the rest of the slip control system. A motor-driven feed of the piston leads to an increase in the pressure in the slip control system, which can be directed by appropriate circuit of control valves targeted to individual wheel brakes. In phases of inactive slip control, the piston can be moved back by motor and the liquid space can be filled again with hydraulic fluid from a reservoir. Such, fundamentally functional a brake booster corresponding unit of a slip control system of the plunger variant should be referred to here as a plunger. For slip control systems designed in such a way, the invention preferably provides that the disengagement unit of the clutch is coupled via the first control valve to the pressure side of a motor-operated plunger of the slip control system.

As is common practice, the disengagement of the clutch is preferably carried out antagonistically against the restoring force of a return spring. Pressure relief of the release unit is thus sufficient to provoke a re-engagement of the clutch. It is therefore preferably provided that the disengagement unit of the clutch is coupled via a second control valve to a low-pressure partial branch of the slip control system. About this second control valve, which should also be referred to as a clutch exhaust valve, the pressure from the disengaging unit of the clutch can be reduced and the corresponding hydraulic fluid directly or indirectly transferred back into the central reservoir or a low-pressure accumulator of the slip control system. The clutch inlet and the outlet valve are preferably associated with correspondingly oriented check valves, preferably as part of the slip control system.

At least one of the aforementioned control valves, preferably both the clutch inlet and the outlet valve, via which the disengagement unit of the clutch is coupled to the slip control system, is preferably designed as a normally closed control valve. This ensures that the current clutch state is maintained in the event of a sudden power failure.

Conveniently, the slip control system is coupled to a clutch control, by means of which the respectively current disengagement request can be generated. The clutch control may be a separate device module; conceivable and particularly preferred for cost reasons, the integration of the functionality in a control unit module, which controls the brake and slip control and / or the transmission in addition to the clutch.

In a first variant, it is provided that the clutch control is set up to determine the requirement of generating a current release request in accordance with predetermined rules from sensory travel situation parameters. In this embodiment, it is thus a fully automatic system which generates the current release request without corresponding input of the vehicle operator.

In an alternative embodiment it is provided that the clutch control is coupled to an actuatable by an operator of the motor vehicle actuator and is adapted to translate actuations of the actuator in each case current disengagement requirements. For example, the actuator may be formed like a conventional clutch pedal, which is followed by a pedal force simulator. The operation of the clutch pedal is passed as an operator input electrically to the clutch control, which generates a corresponding release request ("clutch-by-wire"). Alternatively, the actuator may be configured as a shift lever whose actuation represents the operator request for a gear change, which in turn requires a disengagement of the clutch, so that the clutch control generates a corresponding current disengagement request.

• – das Betätigungsorgan zusätzlich mit der Ausrückeinheit gekoppelt ist,
• – die durch dessen Betätigung mit einem Basisdruck beaufschlagbar ist und
• – das Kupplungssteuergerät eingerichtet ist, die Betätigungen des Betätigungsorgans in solche Ausrückanforderungen zu übersetzen, die die Druckquelle ansteuern, den über den Basisdruck hinaus zum Ausrücken der Kupplung benötigten Druck zu generieren.

As an alternative to these so-called clutch-by-wire or semi-automatic variants, it can be provided that

• - The actuator is additionally coupled to the disengaging unit,
• - Which can be acted upon by the actuation of a base pressure and
• - The clutch control device is adapted to translate the actuations of the actuator in such Ausrückanforderungen that control the pressure source to generate the required pressure above the base pressure for disengaging the clutch.

In this embodiment, therefore, not the entire clutch actuation pressure is generated by the pressure source of the slip control system used according to the invention; Rather, the pressure source is used in the sense of a coupling force amplification, the force of which acts additively to the applied force by means of the actuator.

• – das Betätigungsorgan zusätzlich mit der Ausrückeinheit gekoppelt ist,
• – die durch dessen Betätigung mit einem Basisdruck beaufschlagbar ist und
• – das Kupplungssteuergerät eingerichtet ist, die Betätigungen des Betätigungsorgans in solche Ausrückanforderungen zu übersetzen, die die Druckquelle ansteuern, einen zusätzlichen Volumenstrom mit einem dem Basisdruck entsprechenden Druck zum Ausrücken der Kupplung zu generieren.

As a further variant of the so-called clutch-by-wire or semi-automatic variants, it can be provided that

• - The actuator is additionally coupled to the disengaging unit,
• - Which can be acted upon by the actuation of a base pressure and
• - The clutch control device is adapted to translate the actuations of the actuator in such Ausrückanforderungen that control the pressure source to generate an additional volume flow with a pressure corresponding to the base pressure for disengaging the clutch.

In this embodiment, therefore, not the entire clutch actuation volume is generated by the pressure source of the slip control system used according to the invention; Rather, the pressure source is used in the sense of an additional master cylinder whose volume flow acts additively to the volume supplied by means of the actuator. Thus, it is possible to take over the manual Kupplungsausrücksystems without much change - the master cylinder on the clutch pedal can be taken in principle without any changes and it only need to be adapted to the dimensions of the disengaging unit by z. B. the effective area of the slave cylinder piston is increased. At the same pressure, and possibly also with the same Ausrückweg the disengaging unit, as in the manual system according to the prior art thereby greater Ausrückkräfte be achieved without extending the path of the clutch pedal.

Further features and advantages of the invention will become apparent from the following specific description and the drawings.

Show it:

1 a schematic representation of a first embodiment of a device according to the invention,

2 a schematic representation of a second embodiment of a device according to the invention.

Like reference numerals in the figures indicate like or analogous elements.

1 only shows the parts of the hydraulic system which are helpful for understanding the present invention 10 a motor vehicle, which is equipped with a conventional variant of an ABS and ESP slip control system. In another variant, however, it can only be an ABS system without ESP function.

A brake actuator, in particular a brake pedal 12 is with the master cylinder 14 coupled, which may be a direct mechanical, an electrical or a combined coupling. The master cylinder 14 is designed in the usual way as a tandem cylinder, for reasons of clarity in the other only one brake branch is shown. The second brake arm coupled to the tandem cylinder is designed in the usual way and by the master cylinder 14 outgoing dashed line indicated. It essentially corresponds to the braking portion of the first branch of the system discussed in more detail below, which in turn comprises a brake and a clutch portion.

For a conventional, purely pedal-controlled braking of two are the master cylinder 14 from the rest of the hydraulic system separating separating valves 16 . 18 the first isolation valve 16 opened and the second isolation valve closed. The brake inlet valves 20a . 20b are opened. The remaining control valves, which will be discussed in more detail below, are closed. The pressure generated in the master cylinder acts on the high-pressure branch, the non-illustrated slave cylinder of the two wheel brakes associated with the first branch 22a . 22b , In the ABS case, the first isolation valve is used to reduce the wheel brake pressures 16 and the brake intake valves 20a respectively. 20b closed and the second isolation valve 18 and the brake exhaust valves 24a respectively. 24b open so that the hydraulic fluid through the low-pressure branch of the first branch in the with the master cylinder 14 coupled storage tank 26 can flow back. Usually, in this low-pressure branch part, a low-pressure accumulator 28 arranged, which ensures the maintenance of a minimum pressure in the low-pressure partial branch. To cancel the braking process without ABS activity, the brake pedal 12 back and the brake fluid flows back directly into the master cylinder.

The speed of the wheels is determined by means of the wheel speed sensors 30a . 30b monitored and used as input to the electronic slip control system. By coordinated control of the control valves 16 . 18 . 20a , b, 24a , b if necessary in the context of the ABS, the brake pressure at the wheel brakes 22a , b temporarily reduced. Within the scope of ESP, brake pressure can be applied to individual vehicles outside driver-initiated braking processes wheel brakes 22a , b be created. For isolated control of the wheel brake 22a For example, the first isolation valve 16 and the brake exhaust valve 24a closed while the brake inlet valve 20a and the second isolation valve 18 are open. In this state, the return pump 32 put into operation and sucks hydraulic fluid from the reservoir 26 to order the slave cylinder of the wheel brake 22a to apply pressure. To cancel the brake pressure, the return pump ends 32 their activity and the brake exhaust valve 24a opens, allowing the hydraulic fluid back into the reservoir 26 can flow.

In that regard, the hydraulic system of the invention differs 10 not from conventional systems. For actuating the clutch according to the invention 34 is their not shown in detail slave cylinder via an additional control valve, namely the clutch inlet valve 36 , with the pressure side of the return pump 32 connected. He is also an additional control valve, namely the clutch exhaust valve 38 with the low-pressure partial branch, in particular with the low-pressure accumulator 28 connected. Alternatively, the clutch exhaust valve could 38 also directly with the reservoir 26 be connected.

For isolated control of the clutch 34 become the first isolation valve 16 and the brake intake valves 20a . 20b closed and the second isolation valve 18 open. In addition, the clutch inlet valve 36 opened and the clutch exhaust valve 38 closed. In this state, the return pump 32 Hydraulic fluid from the reservoir 26 suck in and the slave cylinder of the clutch 34 pressurize, resulting in disengagement of the clutch 34 leads against the force of a return spring, not shown. To close the clutch, the clutch inlet valve 36 closed and the clutch exhaust valve 38 open, so that the signal pressure of the clutch 34 in the low-pressure branch, in particular the low-pressure accumulator 28 can be discharged. As a pressure source for the disengaging unit of the clutch 34 thus serves the return pump 32 the slip control system, which only in case of need, that is, when there is a current Ausrückanforderung must be activated. Also, the respectively controlled operating strength of the return pump 32 can be adapted to the current needs, with the fine control of the control pressure also (alternatively or preferably additionally) the clutch inlet valve 36 can be used. In cases where the return pump 32 due to a parallel slip control process is already active, they can also to the disengagement of the clutch 34 to be able to provide the required signal pressure to be driven accordingly stronger. Those skilled in the art will readily understand the control of the control valves required for a combined braking and clutching operation from the schematic drawing of FIG 1 can recognize. Likewise, he will readily understand the function of the non-separately described or provided with separate reference numerals check valves associated with the described elements, due to his expertise.

The above-described control of the individual elements, in particular the control valves and the return pump 32 take place on the basis of defined rules by means of a control unit, not shown separately, which also the current disengagement requirements for the clutch 34 generated or received from upstream facilities. In a fully automatic variant, no clutch actuator is provided to the vehicle operator. The need for a disengagement process is detected in the control unit alone and a corresponding disengagement request is generated. In semi-automatic variants, a selection lever can also act as a clutch actuator by its actuation for gear selection is also interpreted as a trigger for a release request. In a clutch-by-wire system, there is a clutch pedal which is electrically connected to the controller. A pedal force simulator allows the vehicle operator to overcome a mechanical resistance when operating the clutch pedal; However, the triggering of the corresponding release request is purely electrical in the control unit. Finally, a part mechanical variant is possible in 1 dotted is indicated. A clutch pedal 40 is hydraulic with the disengagement unit of the clutch 34 connected. However, by means of the clutch pedal 40 the signal pressure for the clutch 34 not fully generated. Rather, by pressing the clutch pedal 40 only a base pressure, which may be pedal path dependent generated. To disengage the clutch 34 additionally required differential pressure generates the hydraulic system according to the invention 10 in the manner described above. It thus acts as a kind of clutch power amplifier. In another variant, by means of the clutch pedal 40 the volume flow for the clutch 34 not fully generated. Rather, by pressing the clutch pedal 40 only a base pressure, which may be pedal path dependent generated. To disengage the clutch 34 additionally required volume flow with a pressure corresponding to the base pressure generates the hydraulic system according to the invention 10 in the manner described above. Ideally, the clutch control is part of the slip control system, but may also be part of a transmission control.

2 shows an alternative variant of a hydraulic system 10 ' of a motor vehicle. ABS-assisted braking takes place with the brake inlet valves open 20a . 20b , closed brake exhaust valves 24a . 24b and closed clutch inlet valve 36 , To release the brake, the brake inlet valves 20a . 20b closed and the brake exhaust valves 24a . 24b open, so that the master cylinder 14 in the slave cylinder of the wheel brakes 22a , b pressed hydraulic fluid back into the reservoir 26 can flow. In the context of ABS, a relief of the brakes in particular by appropriate control of the brake exhaust valves 24a , b take place. A conventional braking is done by means of the plunger 42 , This includes a servomotor 44 who has a butt 46 which drives a pressure chamber 48 limited. To brake without appropriate pressure generation by means of the brake pedal 12 to initiate or strengthen the piston 46 by means of the engine 44 driven so that hydraulic fluid from the pressure chamber 48 to the brake inlet valves 20a , b flows, the corresponding opening then a corresponding pressurization of the wheel brakes 22a , b (common or separate) causes. At maximum propulsion of the piston 44 becomes the pressure room 48 completely emptied and must be refilled to be available for further operations. For this purpose, the piston 46 by means of the engine 44 actively retracted when the brake valves are closed, so that hydraulic fluid from the reservoir 26 is sucked. Thereafter, the plunger is available again as an on-demand pressure source.

To disengage the clutch 34 becomes the clutch inlet valve 36 open and the engine 44 activated. The one from the plunger 42 generated pressure becomes the slave cylinder of the clutch 34 directed and moves them against the restoring force of a return spring. Close the clutch inlet valve 36 and opening the clutch exhaust valve 38 leads to a closing of the clutch, wherein the hydraulic fluid from the disengaging device of the clutch 34 back to the reservoir 26 is dismissed. Also in this embodiment are fully automatic, semi-automatic, clutch-by-wire and Kupplungskraftverstärkungsvarianten conceivable, the latter in 2 dotted is shown. Concerning. the corresponding description will be on the above 1 Said directed.

Of course, the embodiments discussed in the specific description and shown in the figures represent only illustrative embodiments of the present invention. A broad range of possible variations will be apparent to those skilled in the art in light of the disclosure herein. Typically it will be the brake inlet valves 20a . 20b as "normally open" and the brake exhaust valves 24a . 24b Design as "normally closed" valves.

LIST OF REFERENCE NUMBERS

10

hydraulic system

12

brake pedal

14

Master Cylinder

16

first isolation valve

18

second isolation valve

20a, 20b

Brake inlet valves

22a, 22b

wheel brakes

24a, 24b

Bremsauslassventile

26

reservoir

28

Low-pressure accumulator

30a, 30b

wheel speed sensors

32

Return pump

34

clutch

36

Clutch inlet valve

38

Kupplungsauslassventil

40

clutch pedal

42

plunger

44

engine

46

piston

48

pressure chamber

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19538974 A1 [0002]

Claims (12)

Device for controlling a hydraulically operated clutch ( 34 ) of a motor vehicle, which is equipped with a vehicle to the operation of a plurality of hydraulic wheel brakes ( 22a . 22b ) is provided with a pressure source ( 32 . 42 ) of the slip control system via a first control valve ( 36 ) with a hydraulic disengaging unit of the clutch ( 34 ), characterized in that the pressure source coupled to the disengagement unit of the clutch is used as an active pressure source ( 32 . 42 ) is formed, by means of which a for disengaging the clutch ( 34 ) required pressure in each case according to a current disengagement request can be generated. Device according to claim 1, characterized in that the disengaging unit of the coupling ( 34 ) via the first control valve ( 36 ) with the pressure side of a return pump ( 32 ) of the slip control system is coupled. Device according to claim 1, characterized in that the disengaging unit of the coupling ( 34 ) via the first control valve ( 36 ) with the pressure side of a motor-operated plunger ( 42 ) of the slip control system is coupled. Device according to one of the preceding claims, characterized in that the disengagement unit of the clutch ( 34 ) via a second control valve ( 38 ) with a low-pressure partial branch ( 26 . 28 ) of the slip control system is coupled. Device according to one of the preceding claims, characterized in that at least one control valve ( 36 . 38 ), via which the disengagement unit of the clutch ( 34 ) is coupled to the slip control system, is designed as a normally closed control valve. Device according to one of the preceding claims, characterized in that the slip control system is coupled to a clutch control, by means of which the respective current disengagement request can be generated. Apparatus according to claim 6, characterized in that the clutch control is part of a control of the slip control system and / or a transmission. Device according to one of claims 6 to 7, characterized in that the clutch control is arranged to determine the requirement of generating a current disengagement request according to predetermined rules from sensory driving situation parameters. Device according to one of claims 6 to 7, characterized in that the clutch control with an actuatable by an operator of the motor vehicle actuator ( 40 ) is coupled and set up, actuations of the actuator ( 40 ) in each current release request to translate. Device according to claim 9, characterized in that - the actuator ( 40 ) is additionally coupled to the disengaging unit, which is acted upon by the actuation of a base pressure, and - the clutch control device is set, the actuations of the actuating member ( 40 ) to translate into such release requirements that the pressure source ( 32 . 42 ) beyond the base pressure for disengaging the clutch ( 34 ) to generate required pressure. Device according to claim 9, characterized in that - the actuator ( 40 ) is additionally coupled to the disengaging unit, which is acted upon by the actuation of a base pressure, and - the clutch control device is set, the actuations of the actuating member ( 40 ) to translate into such release requirements that the pressure source ( 32 . 42 ), an additional volume flow with a pressure corresponding to the base pressure for disengaging the clutch ( 34 ) to generate. Using an internal, active pressure source ( 32 . 34 ) one on the operation of a plurality of hydraulic wheel brakes ( 22a . 22b ) acting slip control system of a motor vehicle for generating to disengage a hydraulically actuated clutch ( 34 ) of the motor vehicle required pressures each according to a current disengagement request.

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