METHOD FOR ACTUATING A HYDRAULIC DEVICE

Abstract

Actuation of a hydraulic device that provides a hydraulic supply to a torque-transmitting device is provided. An electrically operated pump is operated in a first operating state. The first operating state; has a primary pump rotational speed that provides a first fluid pressure to the torque-transmitting device via a fluid tract. A switchover process is initiated to operate the electrically operated pump device in a second operating state based on a second fluid pressure and a second fluid target pressure. The second operating state has a secondary pump rotational speed that provides the second fluid pressure to the torque-transmitting device via the fluid tract. During operation of the hydraulic device, the secondary pump rotational speed for the switchover process is determined based on a first power value. The first power value includes electrical pump power of the pump device in a preceding switchover process.

Claims

1. A method for actuating a hydraulic device, which provides a hydraulic supply to a torque-transmitting device, comprising: operating an electrically operated pump device in a first operating state, wherein the first operating state has a primary pump rotational speed that provides a first fluid pressure to the torque-transmitting device via a fluid tract: based on a second fluid pressure and a second fluid target pressure initiating a switchover process to operate the electrically operated pump device in a second operating state, wherein the second operating state has a secondary pump rotational speed that provides the second fluid pressure to the torque-transmitting device via the fluid tract; and during the operation of the hydraulic device, determining the secondary pump rotational speed for the switchover process based on a first power value, the first power value includes electrical pump power of the pump device in a preceding switchover process.

2. The method according to claim 1, further comprising determining the secondary pump rotational speed for the switchover process based additionally on a secondary pump rotational speed for the preceding switchover process.

3. The method according to claim 2, further comprising determining the secondary pump rotational speed for the switchover process based additionally on a rotational speed change value.

4. The method according to claim 1, further comprising calculating the first power value as an averaged electrical pump power over a reference period.

5. The method according to claim 4, wherein reference period is a time interval between a completion time of the preceding switchover process and a completion time of a further switchover process preceding the switchover process in turn.

6. The method according to claim 1, further comprising determining the secondary pump rotational speed for the switchover process based additionally on a second power value, the second power value includes electrical pump power of the pump device in a further switchover processpreceding the preceding switchover process in turn.

7. The method according to claim 3, further comprising determining the secondary pump rotational speed for the switchover process by combining the rotational speed change value and the secondary pump rotational speed in the preceding switchover process.

8. The method according to claim 2, further comprising determining the secondary pump rotational speed for the switchover process basedadditionally on a secondary pump rotational speed for a further switchover process preceding the preceding switchover process in turn.

9. The method according to claim 1, wherein the preceding switchover process immediately precedes the switchover process.

10. The method according to claim 1, wherein the fluid tract has a first fluid branch for supplying the torque-transmitting device with the first fluid pressure and a second fluid branch, which is separated at least in portions from the first fluid branch, for supplying the torque-transmitting device with the second fluid pressure.

11. A method for actuating a hydraulic device, which provides a hydraulic supply to a torque-transmitting device, comprising: operating a first pump in a first operating state, wherein the first operating state has a primary pump rotational speed that provides a first fluid pressure to the torque-transmitting device via a fluid tract; based on a second fluid pressure being less than or equal to a target fluid pressure, initiating a switchover process by operating a second pump in a second operating state, wherein the second operating state has a secondary pump rotational speed that provides the second fluid pressure to the torque-transmitting device via the fluid tract; during operation of the hydraulic device, determining the secondary pump rotational speed for the switchover process based on a first power value for the second pump in a preceding switchover process; and based on the second fluid pressure being greater than or equal to a second target fluid pressure, stopping operation of the second pump.

12. The method of claim 11, wherein the second target fluid pressure is greater than the target fluid pressure.

13. The method of claim 11, further comprising determining the first power value based on electrical energy consumed by the second pump at a completion time of a preceding switchover process and electrical energy consumed by the second pump at a completion time of a further preceding switchover process preceding the preceding switchover process in turn.

14. The method of claim 11, further comprising determine the secondary pump rotational speed for the switchover process based additionally on a second power value for the second pump in a further preceding switchover process preceding the preceding switchover process in turn.

15. The method of claim 14, further comprising determining the secondary pump rotational speed for the switchover process based additionally on a secondary pump rotational speed for the preceding switchover process and a secondary pump rotational speed for the further preceding switchover process.

16. The method of claim 15, further comprising determining the secondary pump rotational speed for the switchover process based additionally on combining a rotational speed change value and the secondary pump rotational speed for the preceding switchover process.

17. The method of claim 11, further comprising, based on the second fluid pressure being less than or equal to the target fluid pressure, stopping operation of the first pump.

18. The method of claim 11, further comprising, based on the second fluid pressure being greater than or equal to the second target fluid pressure, operating the first pump in the first operating state.

19. The method of claim 11, further comprising, upon determining that the switchover process is a first switchover process after initiation of operation for the hydraulic device, determining the secondary pump rotational speed for the switchover process based on a preset initial value.

20. The method of claim 11, wherein the preceding switchover process immediately precedes the switchover process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The disclosure is described in detail below with reference to the drawings. Specifically:

[0030] FIG. 1: shows a block diagram of a hydraulic device for a torque-transmitting device for execution of a method in an exemplary embodiment of the disclosure.

[0031] FIG. 2: shows curve diagrams of various parameters when a method is carried out in the exemplary embodiment of the disclosure.

[0032] FIG. 3: shows a flow chart of a method in the exemplary embodiment of the disclosure.

DETAILED DESCRIPTION

[0033] FIG. 1 shows a block diagram of a hydraulic device 10 for a torque-transmitting device 12 for execution of a method in an exemplary embodiment of the disclosure. The torque-transmitting device 12 is designed as a double clutch and is arranged in a drive train of a vehicle, in particular a motor vehicle, and has a hydraulically actuatable first clutch K1 and a hydraulically actuatable second clutch K2 for alternating torque transmission between a drive element, for example an internal combustion engine and/or an electric motor, and a transmission. The torque-transmitting device 12 may be arranged in a power-shiftable E-axle of the vehicle.

[0034] Furthermore, the torque-transmitting device 12 comprises a hydraulically operated cooling device C for cooling at least one of the two clutches K1, K2. The first clutch K1, the second clutch K2, and also the cooling device C are hydraulically connected to the hydraulic device 10 via a fluid tract 14.

[0035] The hydraulic device 10 comprises an electrically operated pump device PD having a first pump P1 and a second pump P2. The first and second pumps P1, P2 are driven by a common electric motor E. A first fluid branch 16 is assigned to the first pump P1 and a second fluid branch 18 is assigned to the second pump P2. The first pump P1 can be effective in a first operating state of the pump device PD. having a primary pump rotational speed to provide the first fluid pressure pi, The second pump can be effective in a second operating state of the pump device PD, having a secondary pump rotational speed to provide the second fluid pressure p.sub.2.

[0036] Furthermore, a system pressure valve SV is provided, downstream of which there are arranged a first clutch valve KV1 assigned to the first clutch K1, and a second clutch valve KV2 assigned to the second clutch K2 and arranged in parallel with the first clutch valve KV1 ,

[0037] The first pump P1 can provide the first fluid pressure p.sub.1 required for clutch cooling via the cooling device C via the first fluid tract 16. The second pump P2 can provide the second fluid pressure p.sub.2 required to actuate the first and second clutches K1, K2 via the second fluid tract 18. The first clutch valve KV1 is actuatable to control the clutch actuation of the first clutch K1, and the second clutch valve KV2 is actuatable to control the clutch actuation of the second clutch K2.

[0038] Upstream of both the first clutch valve KV1 and the second clutch valve KV2, one spring pressure accumulator SC in each case is connected as hydraulic capacitor. In turn, a check valve RV is arranged in each case upstream of the respective spring pressure accumulator SC. This allows the second pump P2 to increase the second fluid pressure in the second fluid branch 18, thereby charging the spring pressure accumulator SC. wherein a fluid pressure drop towards the second pump P2 is in turn reduced by the corresponding check valve RV.

[0039] However, pressure leakage can also cause a small pressure drop of the second fluid pressure p.sub.2, A control unit S can, in a manner dependent on a ratio between the second fluid pressure p.sub.2 and a second fluid target pressure, initiate, as required and repeatedly, a switchover process during which the second operating state is assumed. In this regard, the first operating state can be temporarily replaced by the second operating state. The switchover process can be a post-pump process by which the second fluid pressure p.sub.2 is brought back to the target pressure level. The secondary pump rotational speed can then be a post-pump rotational speed of the second pump P2.

[0040] FIG. 2 shows curve diagrams of various parameters regarding the execution of a method in the exemplary embodiment of the disclosure. FIG. 2 a) shows the temporal course of the second fluid pressure P.sub.2, FIG. 2 b) the temporally corresponding course of the electrical energy E of the pump device PD, FIG. 2 c) the temporally corresponding course of the pump rotational speed n, and FIG. 2 d) the temporally corresponding course of the electrical pump power P of the pump device PD.

[0041] During operation of the hydraulic device 10, the secondary pump rotational speed n.sub.2 is set by initiating the switchover process as soon as the second fluid pressure p.sub.2 falls below a second fluid target pressure, in this case a minimum second fluid pressure p.sub.2,min. The particular switchover process is set when the second fluid pressure p.sub.2 reaches or exceeds a maximum second fluid pressure p.sub.2,max.

[0042] Provided that there is a point in time t.sub.0 during operation of the hydraulic device 10, there is at least one preceding switchover process U.sub.a, a switchover process U.sub.b preceding this in turn, and a next switchover process U.sub.n following the point in time to. The switchover process U.sub.b is completed at the point in time t.sub.b and the switchover process Ua is completed at the point in time t.sub.a.

[0043] For the next switchover process U.sub.n the method described calculates, during operation of the hydraulic device 10. the secondary pump rotational speed n.sub.2 to be set for the next switchover process U.sub.n at least in a manner dependent on a first power value P.sub.a characterizing the electrical pump power P of the pump device PD in the preceding switchover process U.sub.a. As a result, the energy consumption of the pump device PD can be reduced, and the hydraulic device 10 can set the required second fluid pressure p.sub.2 faster and more accurately. The secondary pump rotational speed n.sub.2 is thus adaptively preset during operation of the torque-transmitting device 12. This makes the second fluid pressure p.sub.2 less susceptible to external influences.

[0044] The secondary pump rotational speed n.sub.2 is set in the next switchover process U.sub.n with the specification of a reduction of the electrical pump power P of the pump device PD to be provided for this purpose, in that the secondary pump rotational speed n.sub.2 in the next switchover process U.sub.n is set to differ from the secondary pump rotational speed n.sub.2 of the preceding switchover process U.sub.a by a rotational speed change value Δn, i.e. lower or higher, as required. For example, the rotational speed variation value Δn can be 200 rpm.

[0045] The first power value P.sub.a is calculated as an averaged electrical pump power over a reference period as follows

[00001]$P_a=\frac{E_a-E_b}{t_a-t_b}$

with the electrical energy E.sub.a consumed by the pump device PD at the point in time t.sub.a and the electrical energy E.sub.b consumed by the pump device PD at the point in time t.sub.b.

[0046] The reference period is the time interval t.sub.a - t.sub.b between the completion of the preceding switchover process U.sub.a and the completion of the switchover process U.sub.b preceding it in turn.

[0047] Preceding the determination of the first power value P.sub.a, a second power value P.sub.b corresponding to the averaged electrical pump power in a comparable period up to the point in time t.sub.b has already been calculated analogously.

[0048] The calculation of the secondary pump rotational speed n.sub.2 to be used for the next switchover process U.sub.n can, for example, be carried out in a case-dependent manner according to the flow chart in FIG. 3. Here, the first power value P.sub.a is first calculated according to (1). Then, the comparison between the first power value P.sub.a and the second power value P.sub.b is made. The subsequent query of the secondary pump rotational speed n.sub.2 is case-dependent according to whether the first power value P.sub.a is smaller or greater than the second power value P.sub.b.

[0049] If the second power value P.sub.b is smaller than the first power value P.sub.b, for example, it is then queried whether the secondary pump rotational speed n.sub.2 in the switchover process U.sub.b is greater than the secondary pump rotational speed n.sub.2 in the switchover process U.sub.a. If this condition is fulfilled, the secondary pump rotational speed n.sub.2 for the next switchover process U.sub.B is set higher than the secondary pump rotational speed n.sub.2 of the preceding switchover process U.sub.a by the rotational speed change value Δn.

[0050] In this regard, the secondary pump rotational speed n.sub.2 to be preset calculated for the next switchover process U.sub.n is narrowed down to a value in a range of values between a minimum secondary pump rotational speed n.sub.2,min and a maximum secondary pump rotational speed U.sub.2,max. The determination of the minimum secondary pump rotational speed n.sub.2,min is useful to limit the switchover process in time. The specification of the maximum secondary pump rotational speed n.sub.2,max can be advantageous to relieve a speed controller of the pump device PD and/or to avoid a maximum permissible secondary pump rotational speed of the pump device PD.

[0051] If the second power value P.sub.b is smaller than the first power value P.sub.B, for example, and the secondary pump rotational speed n.sub.2 in the switchover process U.sub.b is smaller than or equal to the secondary pump rotational speed n.sub.2 in the switchover process U.sub.a, then the secondary pump rotational speed n.sub.2 for the next switchover process U.sub.n is set lower than the secondary pump rotational speed n.sub.2 of the receding switchover process U.sub.3 by the rotational speed change value Δn.

[0052] The change in secondary pump rotational speed n.sub.2 of the next switchover process U.sub.n for other possible states of the case conditions can be taken directly from the diagram.

LIST OF REFERENCE CHARACTERS

[0053] 10 Hydraulic device [0054] 12 Torque-transmitting device [0055] 14 Fluid tract [0056] 16 First fluid branch [0057] 18 Second fluid branch [0058] C Cooling device [0059] E Electric motor [0060] K1 First clutch [0061] K2 Second clutch [0062] KV1 First clutch valve [0063] KV2 Second clutch valve [0064] PD Pump device [0065] P1 First pump [0066] P2 Second pump [0067] S Control device [0068] SC Spring pressure accumulator [0069] SV System pressure valve [0070] p.sub.1 First fluid pressure [0071] p.sub.2 Second fluid pressure [0072] p.sub.2,min Minimum second fluid pressure [0073] p.sub.2,max Maximum second fluid pressure [0074] P Electrical pump power [0075] P.sub.a First power value [0076] P.sub.b Second power value [0077] n.sub.1 Primary pump rotational speed [0078] n.sub.2 Secondary pump rotational speed [0079] n.sub.2,min Minimum secondary pump rotational speed [0080] n.sub.2max Maximum secondary pump rotational speed [0081] Δn Rotational speed change value [0082] U.sub.a Switchover process [0083] U.sub.b Switchover process [0084] U.sub.n Next switchover process