WO2017032373A1

WO2017032373A1 - Method for operating a pulley assembly for driving auxiliary units of a motor vehicle

Info

Publication number: WO2017032373A1
Application number: PCT/DE2016/200394
Authority: WO
Inventors: Benjamin Stober; Philipp Rasch; Jean Sieffert; Joseph GISSLER
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2015-08-24
Filing date: 2016-08-24
Publication date: 2017-03-02
Also published as: DE102015216079A1; DE112016003855B4; CN107848369A; DE112016003855A5; CN107848369B

Abstract

A method is provided for operating a pulley assembly for driving auxiliary units of a motor vehicle, wherein the pulley assembly has a pulley connected via a belt to the auxiliary units and a switchable freewheel for coupling the pulley to and/or decoupling the pulley from a driveshaft of a motor vehicle motor, in which before a stationary air conditioning operation is started in which an electrical machine drives an air-conditioning compressor of an air-conditioning system via the belt, the freewheel is subjected to a switching signal (12) for switching the freewheel into a free-running position for decoupling the pulley and then, before the stationary air-conditioning operation is started, a test torque (14) is introduced into the pulley, wherein the test torque (14) has a lower value than a minimum drag torque of the driveshaft in the idle state and/or a nominal torque for operating the air-conditioning compressor. Using the comparatively low test torque (14) introduced into the pulley, it can be checked whether the freewheel is clamped and, in this case, suitable measures are introduced to remove the clamping before a stationary air-conditioning operation is to be carried out, so that a smooth stationary air-conditioning operation of the motor vehicle is enabled.

Description

Method for operating a pulley arrangement for driving

Auxiliary units of a motor vehicle

The invention relates to a method for operating a pulley arrangement for driving ancillaries of a motor vehicle, with the aid of which it is possible to change between different operating modes.

WO 2015/014361 A2 discloses a pulley arrangement in which a pulley coupled via a belt with ancillary units can be coupled via a switchable pawl freewheel to a drive shaft of a motor vehicle engine. With the aid of a belt-belt generator ("RSG") connected to the belt, in a stationary air-conditioning mode, when the belt pulley is decoupled from the drive shaft of the switched-off motor vehicle engine, an air conditioning compressor of an air conditioning system also connected to the belt can be driven.

There is a constant need to avoid disturbances affecting a stationary air conditioning operation.

It is the object of the invention to provide measures that allow a low-noise stationary air conditioning operation of a motor vehicle.

The object is achieved according to the invention by a method having the features of claim 1. Preferred embodiments of the invention are set forth in the subclaims and the following description, each of which individually or in combination may constitute an aspect of the invention.

According to the invention, a method is provided for operating a pulley arrangement for driving ancillaries of a motor vehicle, wherein the pulley arrangement comprises a pulley connected to the ancillaries via a belt and a switchable freewheel for coupling the pulley with and / or decoupling the pulley from a drive shaft of a motor vehicle. in which before the start of a stationary air conditioning operation in which an electric machine via the belt drives an air conditioning compressor of an air conditioner, the freewheel is subjected to a switching signal for switching the freewheel to a freewheeling position for decoupling the pulley and subsequently before the beginning of the Stand conditioning operation, a test torque is introduced into the pulley, wherein the test torque has a smaller amount than a minimum drag torque of the drive shaft in the idle state and / or as a nominal nominal torque for operation of the air conditioning compressor. Here, the knowledge is exploited that the switchable freewheel can jam in a blocking position in which the pulley is coupled to the drive shaft, and the initiated for switching the freewheeling force may not be sufficient to move the freewheel in the freewheeling position. For example, the freewheel in a first ring pivotally mounted configured as pawls locking elements which can engage in recesses of a coaxial second ring for torque-transmitting locking of the second ring with the first ring. In case of too strong relative rotation of the rings to each other in the locked direction of rotation, the pawl could sit up so far that it is clamped so strong between the first ring and the second ring, that the blocking position of the provided for switching the freewheel actuator does not move into the freewheeling position can be. With a desired auxiliary air conditioning operation, this results in the drive shaft of the switched-off motor vehicle engine being unintentionally coupled to the belt pulley, and a correspondingly high drag torque acting on the belt pulley. The additional drag torque can have the consequence that the torque provided by the electric machine is not sufficient to overcome the drag torque and to drive the air conditioning compressor of the air conditioner. Even if the electric machine can overcome the attacking drag torque, the electric machine must be operated at a significantly higher power, so that the stored in a particular rechargeable battery electrical energy may not be sufficient to actually achieve the provided in the stationary air conditioning operation air conditioning.

Due to the comparatively low test torque, the electric machine with a low power can try to move the belt and the pulley. If the freewheel is not jammed and properly switched to its freewheeling position, the belt and the pulley can be driven by the electric machine. This movement can easily be detected and signal that there is no problem with the freewheel, which would impair a stationary air conditioning operation. Instead, if the belt and the pulley can not be driven by the test torque, this may signal a problem affecting the stationary air conditioning operation. In this case, for example, measures may be taken automatically to release a stuck freewheel and / or issue a warning signal that signals a driver to the problem and informs that a later stationary air conditioning operation may not be possible. Thereby, a problem affecting the auxiliary air conditioning operation can already be recognized and / or solved before a stationary air conditioning operation is intended at all. By introduced into the pulley comparatively low test torque can be checked whether the freewheel is jammed, and in this case appropriate measures to lift the deadlock are initiated before a stationary air conditioning operation is to be made, so that a low-noise stationary air conditioning operation of a motor vehicle is possible. The test torque may in particular be dimensioned such that a spring element of a decoupler provided in the pulley assembly can be biased. When the test torque decreases, the spring element can spring back into its initial position, as a result of which a sudden pulse in the opposite circumferential direction can act on the freewheel. Already this initiated by the decoupler pulse may be sufficient to cancel too much relative rotation of the rings of the freewheel and to solve the deadlock. In particular, the freewheel is integrated in the decoupler, resulting in correspondingly short power transmission paths. Preferably, the initiation of the test torque is repeated at least once. This makes it possible to check whether blockage of the freewheel has already been canceled by the previous initiation of the test torque. Optionally, the amount of the test torque may be increased in the subsequent repetition, respectively. In particular, if after several repetitions of the introduction of the test torque still no movement of the belt and / or the pulley can be detected, an error message can be output. the. In this case, it is also possible that another problem prevents the freewheel in the freewheeling position, for example, an interrupted switching signal to the actuator of the freewheel. A suitable switchable freewheel is described, for example, in WO 2015/021974 A1, to the content of which is incorporated by reference as part of the invention. A first ring of the freewheel can be configured as an inner ring, while a second ring is designed as an outer ring. Alternatively, the first ring may be configured as an outer ring, while the second ring is configured as an inner ring. A ring of the freewheel can in particular be non-rotatably coupled to the pulley, while the other ring can be coupled in particular rotationally fixed to the drive shaft. In particular, a plurality of locking elements are arranged distributed uniformly in the circumferential direction, it being possible that a plurality of blocking in the one circumferential direction first locking elements and a plurality of in a first circumferential direction opposing second circumferential direction locking second locking elements are provided. The first ring and / or the second ring has, in particular, a blocking recess, into which the blocking element can be pressed, in particular, by a switching ring and / or a spring element into the blocking position in order to transmit torque between the first ring and the second ring. In the blocking position, the blocking element can in particular be positively clamped between the first ring and the second ring. The freewheel can be provided in particular in a coupled to a drive shaft of a motor vehicle engine pulley, in particular for driving Kraftfahrzeugnebenaggregaten and / or for connecting a preferably designed as a starter generator electric machine for starting the motor vehicle engine, to couple the pulley on the freewheel with the drive shaft , The freewheel can be designed in particular as a one-sided switchable freewheel or two-way switchable freewheel. The freewheel can be configured for example as a pawl freewheel, sprag freewheel or roller freewheel. For this purpose, the blocking element can in particular be designed as a pivotably mounted pawl, which can preferably be pivoted into a blocking recess in the blocking position. The blocking element can also be configured as a clamping body, which can be tiltably mounted in a cage, for example, and can be tilted by a switching ring into a clamping position which is in particular self-reinforcing in the torque transmission in the blocking position. The Locking element can also be configured as a rolling body, for example cylinder or ball, which can be displaced by a switching ring in the circumferential direction along an inclined plane into a particularly self-reinforcing in the torque transmission clamping position in the blocking position. Depending on the configuration of the blocking element, the blocking element can execute a pivoting movement, a displacement in the radial direction and / or a displacement in the circumferential direction during the movement between the freewheeling position and the blocking position. If, for example, the second ring overruns the first ring, in the locked state of the freewheeling from the second ring, torque can be transmitted to the first ring in the first circumferential direction. When the first ring overruns the second ring, in the locked state of the freewheel from the first ring, a torque transmission to the second ring in a second circumferential direction opposite to the first circumferential direction can take place. In particular, a switching ring for moving the first locking elements between the freewheeling position and the blocking position is provided. The switching ring can be operated for example by means of an actuator preferably against the spring force of a return spring. The return spring can move the switching ring at a declining operating force of the actuator in a defined starting position back. The test torque can be generated in particular by the electric machine. For this purpose, the electric machine is in particular electrically connected to a preferably rechargeable motor vehicle battery. The electric machine is configured in particular as a starter generator, in particular a belt starter generator ("RSG"), in order to start the motor vehicle engine by initiating a correspondingly high starting torque.

The pulley may for example be connected via a flat belt, V-belt, timing belt to an accessory, such as fuel pump, engine oil pump, starter generator, air conditioning compressor. In particular, the belt pulley assembly may include a pulley damper for protecting the belt and / or a crankshaft shifter for protecting the drive shaft to dampen or eliminate torsional vibrations and / or peak moments. In particular, the amount of the test torque is greater than an expected maximum clamping torque of locking elements of the freewheel in a blocking position for coupling the pulley to the drive shaft. This makes it possible to reverse a too strong relative rotation of the rings of the freewheel in a opposite direction provided for the stationary air conditioning operation of the test torque and to overcome the frictional force present in the jammed position.

Preferably, it is provided that, starting from the level of the test torque, the torque introduced into the pulley is increased to the nominal torque for operation of the air conditioning compressor, or the torque introduced into the pulley is reduced to zero starting from the level of the test torque, and only after the end of a rest period, the torque is reduced to zero Pulley-introduced torque is increased to the rated torque for operation of the air conditioning compressor. The test torque can thereby be initiated immediately before the start of the stationary air conditioning operation and in the event that no jammed free-wheeling is detected, be increased to the intended level for the stationary air conditioning operation level. A repeated switching on and off of the electrical machine can be saved. However, it is also possible to provide a rest time between the duration of the applied test torque and the start of the stationary air conditioning operation, in which no torque is generated by the electric machine. As a result, enough time can be provided for a diagnosis of the state of the freewheel. In particular, the test torque can thus be initiated immediately following a situation in which the freewheel is to be switched to the freewheeling position, so that a diagnosis of the freewheel and, if appropriate, a corrective action can be initiated already at a considerable distance from the start of the stationary air conditioning operation , If then the stationary air conditioning operation is to be initiated, it is already ensured that it can be performed, so that the stationary air conditioning operation can begin without time delay. Particularly preferably, the direction of rotation of the test torque is directed against the direction of rotation of the rated torque for operation of the air conditioning compressor. Too strong relative rotation of the rings of the freewheel can be reversed. In particular, when a drive shaft is stationary, the test torque generated by an electric machine is introduced into the belt pulley. When the motor vehicle engine is turned off and the drive shaft is stationary, in a subsequent operating state usually either the motor vehicle engine is started or the stationary air conditioning operation started, wherein the freewheel for the engine start can be in the blocking position and can be moved to the freewheeling position for the stationary air conditioning operation. This makes it possible to initiate the test torque only if there is a signal to initiate the stationary air conditioning operation. An unnecessary switching of the freewheel with the aid of a starting torque to be generated by the electric machine, if the freewheel is to remain in the blocking position anyway for a subsequent engine start, can thereby be avoided. The burden of the freewheel can be kept low and unnecessary energy consumption can be avoided. Preferably, after switching off the motor vehicle engine, in particular in a start / stop situation, and during a rotation of the drive shaft, the freewheel is acted upon by a switching signal for switching the freewheel to the freewheeling position. Due to the rotating drive shaft, one of the rings of the freewheel can be taken along, so that at a low relative rotational speed of the rings of the freewheel and a low applied torque, the freewheel can easily be moved into its freewheeling position. A potentially jammed locking element can be easily solved without this, a separately generated test torque would have to be initiated during the Ausdrehens of the drive shaft. In particular, in this case the test torque can be introduced by the rotational nonuniformity of the motor vehicle engine without the test torque having to be generated by an electric machine for this purpose. The rotational irregularities coming from the motor vehicle engine and introduced into the freewheel via the drive shaft can promote release of the locking elements from the locking recesses and avoid jamming. If necessary, after complete rotation of the drive shaft to standstill, the freewheel is subjected to a switching signal for switching the freewheel to the blocking position, so that the freewheel can already be in the blocking position without jammed locking elements or automatically into the subsequently introduced torque Locked position moves. Particularly preferably it is provided that for starting the motor vehicle engine during the stationary air conditioning operation, in particular by means of the electric machine, the speed of the pulley is lowered below a defined threshold for switching the freewheel, then the freewheel at a speed of the pulley below the switching threshold in a blocking position is switched to couple the pulley with the drive shaft and subsequently, in particular by means of the electric machine, the motor vehicle engine is started. Due to the lowered speed of the freewheel can be switched at a correspondingly low differential speed in its blocking position. As a result, it can be avoided, for example, that the locking elements do not even get into locking recesses or strike so hard in the locking recess that the locking elements bend or jam in the locking recess. The risk that the freewheeling a disturbance in the stationary air conditioning operation occurs, can be reduced. After switching the freewheel into the blocking position, the torque introduced by the electric machine can optionally be increased in order to start the motor vehicle engine. A complete lowering of the speed to zero is not required, so that the motor vehicle engine can be started accordingly fast from the stationary air conditioning operation. In particular, after completion of the stationary air conditioning mode when the motor vehicle engine is switched off, the freewheel is switched to a blocking position for coupling the belt pulley to the drive shaft. By located in the blocking position freewheel then a subsequent starting the motor vehicle engine can be done without delay.

Preferably, the freewheel is acted upon by the stationary pulley with a switching signal for switching the freewheel in the blocking position. If the pulley is completely turned off after completion of the stationary air conditioning operation, the freewheeling operation can be acted upon by the switching signal for the blocking position. In a suitable relative position of the rings of the freewheel can then be moved into the locking recesses without the risk of jamming the locking elements. In a not suitable for this relative position of the rings, the locking elements can be moved at least in the vicinity of the locking recesses and at an incipient starting process for the motor vehicle engine directly into the next Blocking depression arrive without this strong impact forces are to be feared, due to which the locking elements could jam in the locking recesses. Particularly preferably, a switching torque is introduced into the pulley after the application of the freewheel with a switching signal for switching the freewheel to the blocking position to move the freewheel into the blocking position, wherein the switching torque is less than a minimum drag torque of the drive shaft in the idle state and / or as a nominal nominal torque for operation of the air conditioning compressor. If, after the application of the switching signal, the blocking elements of the freewheel have not yet reached the blocking recesses, the rings of the freewheel can be rotated relative to one another by the switching torque, so that the blocking elements can engage in the blocking recesses. Furthermore, the rings of the freewheel can be rotated relative to one another to such an extent that the blocking elements come into contact with one of the stops formed by the circumferentially facing ends of the locking recesses, so that the freewheel already has a largely optimum relative position for a subsequent starting operation of the motor vehicle engine located. The amount of the switching torque can in this case correspond to the amount of the test torque or even be chosen to be even lower, provided that the amount of switching torque is at least so high that the rings of the freewheel can be rotated against each other in the unlocked state. Preferably, the amount of switching torque is so low that in the locked position of the freewheel, the applied drag torque can not be overcome.

The invention will now be described by way of example with reference to the accompanying drawings with reference to preferred embodiments, wherein the features shown below, both individually and in combination may represent an aspect of the invention. Show it:

1 is a diagram of a first operating strategy for the start of a stationary air conditioning operation,

2 is a diagram of a second operating strategy for the start of the stationary air conditioning operation, 3 is a diagram of a third operating strategy for the termination of the stationary air conditioning operation and

4 shows a diagram of a fourth operating strategy for the termination of the stationary air conditioning operation.

In the operating strategy shown in FIG. 1, an automotive engine is switched off, for example, at the beginning of the considered time t, so that an engine speed n _{M of} the motor vehicle engine is below an idle speed 10 and is zero. In this state, for example, the motor vehicle is parked and cooled down or briefly switched off in a start / stop situation. A freewheel of a pulley assembly in this situation is not actuated by an actuator and is in a locked position corresponding to a shift state 12 of "0." A pulley of the pulley assembly is also not rotated so that the pulley has a pulley speed n _R of zero Also, an electric machine configured as a starter-type generator does not engage a belt on the pulley, so that the electric machine outputs a zero torque M. In order to start the stationary air-conditioning operation, first a drive shaft, coupled to the belt pulley via a freewheel, is to be used For this purpose, at the time ti an attempt is made to switch the freewheel into its freewheeling position by a corresponding switching signal, which corresponds to a switching state 12 of "1". Subsequently, the electric machine is operated in the engine mode and outputs a comparatively low test torque 14, which is introduced via the attacking on the electric machine belt in the pulley, which thereby rotates at a test speed 16. For example, by measuring the speed of the pulley, it can be seen that the pulley is rotating. This implies that the freewheel is actually in the freewheeling position and not in the locked position against the switching signal for the switching state 12 has remained because, for example, locking elements of the freewheel have jammed. If the freewheel had been jammed, it would not have been possible to measure the test speed 16 of the pulley at the applied test torque 14. Instead, the speed of the pulley would continue to be essentially zero. As a result of the test speed 16 present in the pulley, the torque M output by the electric machine can subsequently be increased to a nominal torque 18 the belt pulley and a belt-driven air conditioning compressor of an air conditioner with a rated speed of 20 can be driven. The stationary air conditioning operation is thereby achieved without a fault caused by a jammed free wheel.

In the operating strategy illustrated in FIG. 2, in comparison to the operating strategy illustrated in FIG. 1, the test torque 14 generated by the electric machine is introduced into the pulley for a short time only and subsequently returned to zero over a rest period 22. If at a later time, which defines the end of the rest period 22, a stationary air conditioning operation is desired, the nominal torque 18 of the electric machine and the rated speed 20 of the air compressor can be controlled directly, since 22 was already ensured by the test torque 14 before the start of the rest period, that the freewheel is in its freewheeling position. It is also possible to provide the direction of rotation of the belt and the pulley in the opposite direction than in the stationary air conditioning operation (shown in phantom), whereby an optionally present too strong relative rotation of the rings of the freewheel can be reversed. As shown in FIG. 3, when the vehicle engine is to be started in the stationary air conditioning mode, the electric machine may change from the engine operation to the generator operation at a time ti and thereby decelerate the belt, thereby decreasing the rotation speed of the pulley. If the speed of the pulley has fallen below a predefined switching speed, the freewheel is applied at a time t ₂ with a switching signal to change to the blocking state. At a time t ₃ , when the freewheel is safely in the locked state, the engine can initiate a starting torque 24 in the engine and the pulley and coupled via the freewheel drive shaft of the motor vehicle engine to start the motor vehicle engine. After the start of the vehicle engine, the vehicle engine can be operated with its idle speed 10. It is possible that the motor vehicle engine generates such a high power that the generated by the motor vehicle engine torque M for operating the pulley and the air compressor with the rated speed 20 sufficient and possibly even operated in the generator mode electrical Machine drives. As a result, the electric machine can generate electrical energy that can be stored in a rechargeable battery, for example during operation of the electric machine during engine operation during the next stationary air conditioning operation.

If, as shown in FIG. 4, the motor vehicle engine is not to be started in the running stationary air conditioning mode, it is possible at a time ti, when the stationary air conditioning operation is to be ended, to cancel the torque outputted by the electric machine compared to the operating strategy illustrated in FIG. Lower the torque M to zero and let the pulley speed n _R to zero. When the stop of the pulley is reached, the freewheel can be acted upon with a switching signal for switching to the blocking position. Thus, the freewheel actually reaches the blocking position, a low switching torque can be subsequently introduced into the pulley briefly by the electric machine to ensure that the blocking elements of the freewheel are inserted into the locking recesses. In a subsequent start of the motor vehicle engine, the starting torque 24 can be generated directly without time delay from the electric machine, without fear of a disturbance or delay caused by the freewheel.

The operating strategy illustrated in FIG. 3 and / or in FIG. 4 may be connected in time to the operating strategy illustrated in FIG. 1 and / or in FIG. 2.

LIST OF REFERENCES

10 idle speed

12 switching state

14 test moment

16 test speed

18 rated torque

20 rated speed

22 rest period

24 starting moment

26 switching torque

M torque

n _M engine speed

n _R Belt pulley speed

t time

Claims

claims

Method for operating a pulley arrangement for driving ancillaries of a motor vehicle,

the pulley assembly comprising a pulley connected to the accessories via a belt and a switchable freewheel for coupling the pulley with and / or decoupling the pulley from a drive shaft of an automotive engine,

in which before the start of a stationary air conditioning operation, in which an electric machine via the belt drives an air conditioning compressor of an air conditioner, the freewheel with a switching signal (12) for switching the freewheel is acted upon in a freewheeling position for decoupling the pulley and

subsequently introducing a test torque (14) into the pulley prior to the start of the stationary air conditioning operation, the test torque (14) being less than a minimum drag torque of the drive shaft in the idle state and / or a nominal nominal torque for operating the air conditioning compressor.

The method of claim 1, wherein the amount of the test torque (14) is greater than an expected maximum clamping torque of locking elements of the freewheel in a locking position for coupling the pulley to the drive shaft.

Method according to Claim 1 or 2, in which, starting from the level of the test torque (14), the torque (M) introduced into the pulley is increased to the rated torque (18) for operation of the air conditioning compressor or, starting from the level of the test torque (14), into the Pulley-introduced torque (M) is lowered to zero and only after a rest period (22), the introduced into the pulley torque (M) is increased to the rated torque (18) for operation of the air conditioning compressor.

4. The method according to any one of claims 1 to 3, wherein the direction of rotation of the test torque (14) is directed against the direction of rotation of the nominal torque for operation of the air conditioning compressor.

5. The method according to any one of claims 1 to 4, wherein in a stationary drive shaft, the test torque generated by an electric machine (14) is introduced into the pulley.

6. The method according to any one of claims 1 to 5, wherein after switching off the motor vehicle engine, in particular in a start / stop situation, and during a boring of the drive shaft of the freewheel is acted upon by a switching signal for switching the freewheel in the freewheeling position.

7. The method according to any one of claims 1 to 6, wherein for starting the motor vehicle engine during the stationary air conditioning operation, in particular with the aid of the electric machine, the speed (n _R ) of the pulley is lowered below a defined threshold for switching the freewheel, then the freewheel is switched at a speed (n _R ) of the pulley below the switching threshold in a blocking position for coupling the pulley to the drive shaft and subsequently, in particular by means of the electric machine, the motor vehicle engine is started.

8. The method according to any one of claims 1 to 7, wherein after completion of the stationary air conditioning mode with the motor vehicle engine, the freewheel is switched to a blocking position for coupling the pulley to the drive shaft.

9. The method of claim 8, wherein the freewheel with a stationary pulley with a switching signal (12) is acted upon for switching the freewheel in the blocking position.

10. The method of claim 9, wherein after applying the freewheel with a switching signal (12) for switching the freewheel in the blocking position a switching torque (26) is introduced into the pulley to move the freewheel in the locked position, wherein the switching torque (26) has a lower amount than a minimum drag torque of the drive shaft in the idle state and / or as a nominal nominal torque for operation of the air conditioning compressor.