WO2015014357A1

WO2015014357A1 - Hydraulic actuation system

Info

Publication number: WO2015014357A1
Application number: PCT/DE2014/200313
Authority: WO
Inventors: Dominik Herkommer; Roshan Willeke
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2013-07-31
Filing date: 2014-07-10
Publication date: 2015-02-05
Also published as: DE112014003503B4; DE102014213489A1; DE112014003503A5

Abstract

The invention relates to a hydraulic actuation system comprising a pump actuator as a generator with a pump conveying a hydraulic medium from a reservoir, a slave cylinder and an intermediate hydraulic line. The invention is characterized in that a non-return valve is arranged between the pump and the slave cylinder, said non-return valve being actively connected to a freewheel such that said non-return valve is only closed when the pump is at a standstill for maintaining the momentary pressure.

Description

Hydraulic actuation system

The invention relates to a hydraulic actuation system with a pump actuator as a donor with a pump from a reservoir hydraulic medium pump, a slave cylinder and an intermediate hydraulic line. In particular, the invention relates to an actuator, especially a pump actuator for use as a clutch actuator in motor vehicles.

Such pump actuators for clutches consist essentially of a normal positive displacement pump with a constant volume flow. When holding a pressure, ie when the clutch is actuated, unwanted leaks occur and the holding current in an electrically driven pump increases. To avoid these disadvantages, an additional valve can be installed, which, however, must be provided with its own cost-intensive control. Further cost drivers are the magnet and the coil.

Therefore, the object is to avoid these disadvantages.

The task is solved by an automatically operated sealing concept for the holding phase of the clutch actuation to minimize the leakage (and thus the current consumption of the actuator). So it is presented an automatic passive valve.

The passive valve is a combination of a check valve with a freewheel that is directly or indirectly coupled to the pump shaft.

The combination of freewheel and check valve is such that the valve is closed only when the pump is stopped to maintain the instantaneous pressure. The valve is closed by the pressure difference between the stationary pump and the slave side. This pressure difference is caused by leakage in the pump. If a volume is delivered, ie the pressure on the slave side is increased, then the check valve opens due to the excess pressure generated on the pump side. If the volume is pumped back again, ie reduced pressure on the slave side, the freewheel opens by the reverse direction of rotation of the check valve directly or by means of an additional connection.

The valve device is characterized by the following points: - Coupling of the pump drive with the valve

- Combination of freewheel and valve

- Automatic shut-off valve at standstill of the pump

- Operation of the pump in pumping and in suction direction possible.

The above object is achieved in a hydraulic actuation system with a pump actuator as a donor with a pump from a reservoir hydraulic medium pump, a slave cylinder and an intermediate hydraulic line, alternatively or additionally in that between the pump and the slave cylinder, a check valve is arranged the check valve is operatively connected to a freewheel so that the check valve is closed only when the pump is stopped to hold the instantaneous pressure. The hydraulic actuation system is preferably a hydraulic clutch actuation system for actuating a clutch. In this case, the pump actuator according to the invention replaces a conventional master cylinder.

A preferred embodiment of the hydraulic actuation system is characterized in that the freewheel is coupled directly or indirectly with a pump shaft. The freewheel includes, for example, freewheel bodies that lock or free in response to a direction of rotation of the pump shaft. With a direct coupling of the freewheel with the pump shaft, the freewheel bodies have direct contact with the pump shaft. In an indirect coupling of the freewheel with the pump shaft, for example, a transmission body, in particular a wheel or a roller rotatably connected to the pump shaft. The freewheel bodies then have no direct contact with the pump shaft. In the indirect coupling, the freewheel bodies have contact with the transfer body, for example with the wheel or with the roller. Freewheel body sliding curves are advantageously associated with the freewheel bodies, which lock or freewheel the freewheel body depending on the direction of rotation of the pump shaft. In the indirect coupling of the freewheel with the pump shaft of the transfer body is a coupling device. The coupling device may also include a coupling rod, via which a check valve body of the check valve with a freewheel body of the freewheel can be coupled. A further preferred embodiment of the hydraulic actuation system is characterized in that the pump is operable in opposite conveying directions. In a first conveying direction, the pump delivers hydraulic fluid from the reservoir via the open check valve into the slave cylinder. In a second conveying direction, the pump delivers hydraulic fluid from the slave cylinder via the open check valve back into the reservoir.

A further preferred embodiment of the hydraulic actuating system is characterized in that the check valve comprises a check valve body which is mechanically coupled to a freewheel body of the freewheel. The check valve body can be coupled directly or indirectly with the freewheel body of the freewheel. About the coupling between the freewheel body and the check valve body can be effected in a simple manner opening the check valve to allow a delivery of hydraulic fluid from the slave cylinder in the reservoir.

Another preferred embodiment of the hydraulic actuating system is characterized in that the check valve body is designed as a check valve flap. The check valve flap can interact directly with a freewheel body of the freewheel.

A further preferred embodiment of the hydraulic actuation system is characterized in that the non-return valve body and / or one or the freewheel body is biased by a spring means / is. The check valve body is biased, for example by a spring in a closed position in which the check valve is closed. The freewheel body is held by the prestressed spring device, for example by a spring, in contact with the pump shaft or the coupling device, in particular the transmission body.

Another preferred embodiment of the hydraulic actuation system is characterized in that the check valve body is combined with a seal. This can be ensured in a simple manner, a high tightness with closed check valve. Another preferred embodiment of the hydraulic actuating system is characterized in that the freewheel is associated with a hydraulic separating device. The hydraulic separator may include, for example, a seal that prevents unwanted drainage of hydraulic fluid to the freewheel. The hydraulic separator may also comprise a membrane by which the freewheel or parts of the freewheel are hydraulically encapsulated.

Another preferred embodiment of the hydraulic actuation system is characterized in that the check valve body via a coupling rod with one or the freewheel body of the freewheel can be coupled. About the coupling rod can be transmitted to the check valve body in a simple manner, a movement of the freewheel body to move the check valve body from its closed position to its open position.

The invention further relates to a coupling with a previously described

hydraulic actuation system. In this case, the pump actuator according to the invention replaces a conventional master cylinder.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail. Show it:

Figure 1 is a schematic diagram of a hydraulic actuation system with a

Pump actuator and with a clutch;

Figure 2 shows an embodiment of a check valve of the clutch actuator of Figure 1 at a standstill;

FIG. 3 shows the check valve from FIG. 2 with an indicated volumetric flow in the direction of the coupling:

4 shows the check valve on Figure 2 with an indicated flow in the direction of the pump and Figure 5 shows another embodiment of a check valve with a sealing seat.

FIG. 1 shows in simplified form an actuating arrangement 1 which comprises a hydraulic actuating system with a pump actuator 2 and a coupling 3. The pump actuator 2 comprises a pump 6, which is driven by a motor 4 via a pump shaft 8. The motor 4 is designed, for example, as an electric motor, which is controlled by a control unit 5. The control unit 5 is also referred to as Local Control Unit, abbreviated LCU.

The pump actuator 2 further comprises a valve 7 designed as a check valve. The check valve 7 is mechanically coupled to the pump shaft 8, as indicated by an arrow 9.

When the pump 6 is driven via the pump shaft 8, then it promotes hydraulic medium from a reservoir 10 into a hydraulic line 11, as indicated by a triangular symbol within a circle symbolizing the pump 6. However, the pump 6 may also, unlike shown, promote hydraulic fluid from the hydraulic line 1 1 back into the reservoir 10 when it is operated in an opposite conveying direction.

The hydraulic line 1 1 passes through the valve 7 and connects an output of the pump 6 with a slave cylinder 12. The slave cylinder 12 includes a slave piston 13 which is coupled via an engagement bearing 14 with a pressure plate 15 of the clutch 3. About the slave piston 13 and the engagement bearing 14 and an unspecified cup spring device or lever spring means, an actuating force can be applied to the pressure plate 15.

FIG. 1 shows the actuation concept 1 of the pump actuator with the valve proposed here. The arrangement can be subdivided into actuator 2 and coupling 3. The valve 7 belongs schematically to the actuator and, like the pump 6, is coupled to the actuator motor 4. The line 11 from the pump to the coupling passes through the valve.

In FIGS. 2 to 4, a valve 20 designed as a check valve is shown in various states. The valve 20 comprises a valve flap or check valve flap 21. The check valve flap 21 closes an opening in a partition wall 60 in FIG between a pump side 26 and a coupling side 27. In FIGS. 3 and 4, the valve flap 21 is opened, so that a connection between the pump side 26 and the coupling side 27 is released.

The indicated in Figure 1 by the arrow 9 coupling between the pump drive and the valve is carried out according to an aspect of the invention by a freewheel. The freewheel comprises at least one freewheel body 22, which has free contact with a roller 23 which is associated with the pump drive. The roller 23 is, for example, non-rotatably connected to a pump shaft of the pump. The freewheel further comprises two Freilaufkörper- slide curves 24, 25, which serve to represent a freewheeling function and a lock function.

In Figure 3, the freewheel body 23 has due to a direction indicated by an arrow 29 direction of rotation of the roller 23 in contact with the Freilaufkörpergleitkurve 24, which serves to represent the freewheeling function. In Figure 4, the freewheel body 22 has due to a direction indicated by an arrow 30 rotational direction of the roller 23 in contact with the Freilaufkörpergleitkurve 25, which serves to represent the blocking function of the freewheel. By blocking the freewheel body 22 opens the valve flap 21 in Figure 4. By dotted arrows 28 are indicated in Figures 3 and 4 different flow directions when the valve flap 21 is open.

Figure 2 shows the valve 20 while the pump 6 is stationary. The seal is shown here as a flap 21. On the left of this flap 21 is the pump side 26, to the right of the clutch side 27. During standstill, the flap 21 is closed by the fact that the pressure on the pump side 26 decreases by leakage and therefore the flap 21 pressed by the higher pressure on the clutch side 27 becomes.

Therefore, the other elements of the valve are currently not engaged. These are: the roller 23 may be an additional roller connected with or without translation to the spindle of motor or pump, may be a roller sitting on one of these spindles, or may be directly one of these spindles. Also, motor and pump can sit on the same spindle. Important is the direct mechanical coupling between the motor, pump and the wheel referred to here as a roller.

On this roller sits a freewheel body 22. This can be pressed by a spring, which is not shown here. This might have the advantage of a quieter fes, as well as more reliable gripping the freewheel. The movement of the freewheel body can be limited by the freewheel body sliding curves 24, 25.

Figure 3 shows the valve while being pumped towards the clutch. The valve flap 21 is pressed by the higher pressure on the pump side 26 so that the volume flow 28 can pass unhindered. The roller 23 thereby rotates 29 so that the freewheel body 22 is pressed against the freewheel body sliding curve 24 removed from the valve flap 21.

Figure 4 shows the valve while pumping fluid out of the coupling. Now, the roller 23 rotates (see arrow 30) so that the freewheel body 22 is pressed against the freewheel body sliding curve 25 while the flap 21 stops. Thus, despite the higher pressure on the clutch side 27, the fluid can flow to the pump (see arrow 28).

FIG. 5 indicates a valve 40 which is likewise designed as a check valve and which can be coupled via a roller 41 to a drive of the pump (6 in FIG. 1). By a double arrow is indicated that the roller 41 is rotatable in opposite directions. By appropriate control, the pump can promote in opposite directions.

The roller 41 is in contact with a freewheel body 42 of a freewheel. The freewheel body 42 is held in contact with the roller 41 by a spring 43. To illustrate a freewheeling function and a blocking function of the freewheel body 42 two Freilaufkörpergleitkurven 44 and 45 are assigned. The freewheel body slip curve 44 is used to represent the freewheeling function. The Freilaufkörpergleitkurve 45 serves to illustrate the blocking function of the freewheel.

When the freewheel body 42, depending on the direction of rotation of the roller 41 comes into contact with the Freilaufkörpergleitkurve 45, then the freewheel body 42 also comes into contact with a lower end in Figure 5 end of a coupling rod 46. The coupling rod 46 is in Figure 5 upwards and downwards guided below movable. The coupling rod 46 is associated with a seal 47, which prevents undesired outflow of hydraulic fluid from a pump side 51 in the direction of freewheel and pump drive.

The pump side 51 is separated from a coupling side 52 by a partition wall 70. In the partition wall 70, a passage opening is provided which can be closed by a check valve body 49 of the valve 40. The check valve body 49 is provided with a tion 48 provided, which serves to represent a sealing seat. By a spring 50 of the check valve body 49 is biased with the seal 48 in its closed position shown in Figure 5.

FIG. 5 shows an embodiment with a sealing seat. Here is an ordinary check valve 49 with gasket 48 is used. The valve can be opened via the coupling rod 46. The coupling rod is connected to a freewheel device similar to Figure 2. In this embodiment, a spring 43 is shown, which presses the freewheel body 42 against the roller 41. The freewheel body opens the valve when turned counterclockwise. So this is the direction in which the pump sucks.

The fluid flows or is promoted so that at higher pressure on the pump side 51, the valve is opened, and is closed at higher pressure on the clutch side 52. This closing is additionally supported by the spring 50.

The arrangement is further guided so that the volume flow is separated by the seal 47 on the coupling rod of the freewheel device. This separation can be implemented constructively with a membrane and a split coupling rod to seal reliable and frictionless.

Thus, a valve arrangement is proposed which automatically closes when the pump is at a standstill, thus minimizing the leakage. Nevertheless, the pump can continue to work in both directions.

LIST OF REFERENCES

actuator assembly

actuator

clutch

engine

LCU (Local Control Unit)

pump

Valve

wave

Coupling between pump drive and valve reservoir

hydraulic line

slave cylinder

slave piston

engagement bearing

pressure plate

Valve

valve flap

Freewheel body

Roller / pump drive

Freilaufkörpergleitkurve

pump side

coupling side

Arrow (indicator volumetric flow)

Arrow (indicator direction of rotation)

Valve

Roller / pump drive

Freewheel body

feather

Freilaufkörpergleitkurve Freewheel body slip curve Coupling rod

poetry

Check valve body spring

pump side

Coupling side partition wall

partition wall

Claims

claims

1 . Hydraulic actuating system with a pump actuator (2) as an encoder with a pump (6) conveying a hydraulic fluid from a reservoir (10), a slave cylinder (12) and an intermediate hydraulic line (1 1), characterized in that between the pump (6) a non-return valve (7; 20; 40) is arranged, wherein the check valve (7; 20; 40) is operatively connected to a freewheel such that the check valve (7; 20; 40) is only at standstill of the pump (6) is closed to hold the current pressure.

2. Hydraulic actuation system according to claim 1, characterized in that the freewheel is directly coupled to a pump shaft (8).

3. Hydraulic actuation system according to claim 1, characterized in that the freewheel is coupled indirectly, for example by a coupling device (9) with a pump shaft (8).

4. Hydraulic actuating system according to one of the preceding claims, characterized in that the pump (6) is operable in opposite conveying directions.

5. Hydraulic actuating system according to one of the preceding claims, characterized in that the check valve (7; 20; 40) comprises a check valve body (49) which is mechanically coupled to a freewheel body (22; 42) of the freewheel.

6. Hydraulic actuation system according to one of the preceding claims, characterized in that the check valve body is designed as a check valve (21).

7. Hydraulic actuation system according to one of the preceding claims, characterized in that the check valve body (49) and / or one or the freewheel body (22; 42) are biased by a spring device (50) / is.

8. Hydraulic actuation system according to one of the preceding claims, characterized in that the check valve body (49) with a seal (48) is combined.

9. Hydraulic actuation system according to one of the preceding claims, characterized in that the freewheel is associated with a hydraulic separating device (47).

10. Hydraulic actuation system according to one of the preceding claims, characterized in that the check valve body via a coupling rod (46) with one or the freewheel body (42) of the freewheel is coupled.