DE102021121012A1 - Method for controlling a hydraulic device - Google Patents

Abstract

The invention relates to a method (76) for controlling a hydraulic device (10) having a system pressure branch (18) in which a system pressure is present, at least one first clutch actuating valve (24) effective between the system pressure branch (18) and a clutch pressure branch (20), in to which a clutch pressure (p1) is present for actuating a first clutch (12), the clutch pressure (p1) being increased above the system pressure (pa) initially set below the clutch pressure (p1) by the system pressure ( pt) using a first pressure gradient (G1) within a first period of time (Δt1) down to a first system pressure value (pt1), which is a first pressure difference (Δp1) below a first pressure value (p11) of the applied clutch pressure (p1) and in a subsequent second step (S2) using at least one compared to the first pressure gradient (G1) smaller second pressure gradient (G2) within a second Period of time (Δt2) greater than the first system pressure value (pt1) and greater than the first pressure value (p11) is set.

Description

The invention relates to a method for controlling a hydraulic device according to the preamble of claim 1.

A method for controlling a hydraulic device for a torque device is, for example, in DE 10 2019 130 158 described. The torque device is designed as a dual clutch and has a first and second clutch, each of which can be actuated by a clutch pressure in a clutch pressure branch and is hydraulically connected to a system pressure branch. The actuation of the respective clutch is controlled by a clutch pressure valve assigned to the individual clutch as a function of a system pressure provided by a pump in the system pressure branch.

The object of the present invention is to carry out the clutch actuation in a more comfortable and precise manner.

At least one of these objects is solved by a method having the features of claim 1. This allows the clutch to be actuated more comfortably and accurately.

The clutch can be operated more smoothly and with less energy. The pressure fluctuations in the hydraulic device can be reduced. The hydraulic device can be controlled more accurately and reliably.

The hydraulic device can be installed in a vehicle. The first clutch can be arranged between a drive element, for example an internal combustion engine or an electric motor, and a driven element, for example a transmission, for torque transmission. The hydraulic device can be set up to control a further, second clutch. The first and second clutch can be associated with a double clutch. The first and/or second clutch can be designed as a brake.

The clutch actuation valve can be actuated electromagnetically. The clutch actuation valve can have a slide that can be actuated, preferably electromagnetically, and can assume at least two positions on which a valve state of the clutch actuation valve depends. The clutch actuation valve can have a port for hydraulic connection to the clutch pressure branch, a port for hydraulic connection to the system pressure branch and a port for connection to a fluid reservoir. In a first valve state, the clutch actuation valve can hydraulically connect the clutch pressure branch to the system pressure branch and in a second valve state, the clutch pressure branch to the fluid reservoir. The slider can set the first valve state in a first position and the second valve state in a second position.

In a preferred embodiment of the invention, it is advantageous if the first clutch actuation valve is at least partially open in the first and/or second step for hydraulically connecting the system pressure branch to the clutch pressure branch. The first clutch actuation valve can be fully open in the first and/or second step.

In a special embodiment of the invention, it is advantageous if, in a third step immediately following the first step and immediately preceding the second step, the system pressure is set to be constant over a third period of time. As a result, the pressure dynamics arising from the first step can be reduced. The pressure fluctuations in the system pressure branch and in the clutch pressure branch can be reduced.

In a preferred embodiment of the invention, it is provided that the third period of time is shorter than the second period of time. The third period of time can also be greater than the second period of time.

In a preferred embodiment of the invention, it is advantageous if the second pressure gradient is constant within the second period of time. The pressure gradient can also be variable within the second period of time. The second pressure gradient and then a further pressure gradient deviating from this can be set within the second period of time. The further pressure gradient can be smaller or larger than the second pressure gradient.

A preferred embodiment of the invention is advantageous in which the clutch pressure is set independently of the system pressure before the first step is initiated. A first check valve, which maintains the clutch pressure in the clutch pressure branch independently of the system pressure, can be arranged between the system pressure branch and the clutch pressure branch.

In a preferred embodiment of the invention, it is advantageous if the first clutch is operated in a slipping manner at least when the first step is initiated. In a slipping operation of the first clutch, pressure fluctuations in the clutch pressure in the first clutch pressure branch can have a disadvantageous and noticeable effect. Spe Especially in the slipping operation, the application of the proposed method can reduce an adverse effect of changes in the system pressure on the operation of the first clutch.

A preferred embodiment of the invention is advantageous in which the first pressure difference is defined as a function of the first pressure gradient. This can prevent a large overshoot of the clutch pressure at the first step.

A preferred embodiment of the invention is advantageous in which the system pressure is provided by a pressure supply unit that can be switched between a first and second operating mode, the first operating mode being set when the first step is initiated and the second operating mode providing a pressure supply for cooling. In the first operating mode, the pressure supply unit can provide a higher system pressure than in the second operating mode with a lower fluid flow at the same time. The pressure supply unit can be a hydraulic pump. The first operating mode can be set during the first and/or second step.

In a preferred embodiment of the invention, it is provided that an increase in the clutch pressure due to the system pressure is limited to the first operating mode. In the second mode of operation, the clutch pressure can be maintained independently of the system pressure. In the second operating mode, the clutch pressure can be independent of the system pressure via a check valve.

Further advantages and advantageous configurations of the invention result from the description of the figures and the illustrations.

character list

• 1: Eine Hydraulikvorrichtung in einer speziellen Ausführungsform der Erfindung.
• 2: Einen Querschnitt eines Kupplungsbetätigungsventils einer Hydraulikvorrichtung in einer speziellen Ausführungsform der Erfindung.
• 3: Ein Zeitdiagramm verschiedener Parameter einer Hydraulikvorrichtung bei Anwendung eines Verfahrens in einer speziellen Ausführungsform der Erfindung.

The invention is described in detail below with reference to the figures. They show in detail:

• 1 : A hydraulic device in a specific embodiment of the invention.
• 2 : A cross section of a clutch operating valve of a hydraulic device in a specific embodiment of the invention.
• 3 : A timing diagram of various parameters of a hydraulic device when using a method in a specific embodiment of the invention.

1 shows a hydraulic device 10 in a special embodiment of the invention. The hydraulic device 10 is installed in a vehicle and set up for actuating a first clutch 12 and a second clutch 14, and for cooling. The first and second clutches 12, 14 can be associated with a double clutch 16, which is arranged for torque transmission between a drive element, for example an internal combustion engine, and an output element, for example a transmission.

Hydraulic device 10 has a system pressure branch 18, in which a system pressure is present, and a first clutch pressure branch 20, which is hydraulically connected to system pressure branch 18 via a first check valve 22 and a downstream first clutch actuating valve 24, and a second clutch pressure branch 26, which is connected via a second check valve 28 and a downstream second clutch actuation valve 30 is hydraulically connected to the system pressure branch 18 . The first and second clutch actuation valves 24, 30 are each connected to a fluid reservoir 32, bypassing the first and second check valves 22, 28. The respective check valve 22, 28 allows the clutch pressure in the associated clutch pressure branch 20, 26 to be maintained independently of the system pressure.

The first clutch 12 can be actuated via a first actuating device 34 as a function of the first clutch pressure. In this case, the first clutch 12 can be actuated when the pressure value of the first clutch pressure is above a default value and not actuated when the value falls below the default value. The first check valve 22 allows the first clutch 12 to remain actuated while maintaining the first clutch pressure, although the system pressure, via which the first clutch pressure was previously built up, is below the existing first clutch pressure. Therefore, the system pressure can be lowered even if the first clutch pressure for actuating the first clutch 12 needs to be maintained. The energy consumption of the hydraulic device 10 can be reduced and the actuation of the first clutch 12 can take place in a more energy-saving manner.

The second clutch 14 can be actuated via a second actuating device 36 as a function of the second clutch pressure. In this case, the second clutch 14 can be actuated when the pressure value of the second clutch pressure is above a specified value and not actuated when the value falls below the specified value. The second check valve 28 allows the second clutch 14 to remain actuated while maintaining the second clutch pressure, although the system pressure over which the second clutch development pressure was previously built up, is below the existing second clutch pressure. Therefore, the system pressure can be lowered even if the second clutch pressure for actuating the second clutch 14 has to be maintained.

A pressure supply unit 38 is connected on the suction side via a suction filter 40 to the fluid reservoir 32 and the system pressure branch 18 and provides the system pressure in the system pressure branch 18 at least in a first operating mode. The system pressure branch 18 is hydraulically connected to a high-pressure connection 42 of the pressure supply unit 38 .

The pressure supply unit 38 is designed as an electrically driven tandem pump unit 44, which can alternately assume a second operating mode with the first operating mode.

For cooling, the hydraulic device 10 comprises a cooling branch 46 which has a fluid flow in the second operating mode of the pressure supply unit 38 . The cooling branch 46 is connected to a low-pressure connection 48 of the pressure supply unit 38 and, for cooling an electric motor 50, via a first cooling branch 52 for cooling a transmission, a second cooling branch 54 for cooling a braking device and a third cooling branch 56 for further cooling with the fluid reservoir 32. A fluid cooler 58 is coupled in the cooling branch 46 to cool the fluid in the cooling branch 46 before it flows through the electric motor 50 . The fluid cooler 58 can be an oil-water cooler.

A system pressure valve 60 is arranged between the system pressure branch 18 and the fluid accumulator 32 in order to change the system pressure in the system pressure branch 18 .

2 Fig. 12 shows a cross section of a clutch operating valve of a hydraulic device in a specific embodiment of the invention. The clutch actuation valve is embodied as a first clutch actuation valve 24 and can be actuated electromagnetically. The first clutch actuation valve 24 can have an electromagnetically actuable slide 62 which can assume at least two positions on which the valve state of the first clutch actuation valve 24 depends. The first clutch actuation valve 24 has a port 64 for hydraulic connection to the first clutch pressure branch, a port 66 for hydraulic connection to the system pressure branch and a port 68 for connection to a fluid reservoir.

In a first valve state, the first clutch actuation valve 24 can hydraulically connect the first clutch pressure branch to the system pressure branch and in a second valve state the first clutch pressure branch to the fluid reservoir. The slide 62 can set the first valve state in a first position and the second valve state in a second position. The first clutch pressure acts against an adjusting force 70 of the slide 62 and is for this purpose on a pressure side 72 of the slide 62, which is opposite the actuating side 74 of the slide 62, and acts on the slide 62 as a control pressure.

3 FIG. 7 shows a timing diagram of various parameters of a hydraulic device when using a method 76 in a specific embodiment of the invention. In the time diagram, the uniform course of time from a speed n in 3 a) , a torque N in 3 b) , an actuation current I of a valve actuation in 3 c) , a pump speed np of the pressure supply unit in 3d) , a pressure p in 3e) and an actuation path d in 3 f) pictured.

In 3 a) the speed nm of the drive element, for example the internal combustion engine, and the speed n1 of the first transmission input shaft, which is connected to an output side of the first clutch, are shown.

In 3 b) the clutch setpoint torque Nt1 of the first clutch, the engine torque Nm of the internal combustion engine and the actual clutch torque Na1 of the first clutch are shown.

In 3c) shows the electrical actuation current Is of the system pressure valve and the electrical actuation current I1 of the first clutch actuation valve.

In 3e) shows the first clutch pressure p1, the target system pressure pt and the actual system pressure pa.

In 3 f) the actuation path d1 of the actuation device of the first clutch is shown.

Before the point in time t1, the actual system pressure pa and the target system pressure pt are below the first clutch pressure p1. Beginning at time t1, the first clutch pressure p1 should be increased in order to increase the first actual clutch torque Na1. In a first step S1, within a first time period Δt1, the first system setpoint pressure pt is abruptly increased using a first pressure gradient G1 to a first system setpoint pressure value pt1, which is a first pressure difference Δp1 below the first clutch pressure present at time t1 with a first pressure value p11 p1 and in a subsequent second step S2 using at least one second and approximately constant pressure gradient G2, which is smaller than the first pressure gradient G1, within a second time period Δt2, starting from time t3 to time t4, greater than the first system pressure value pt1 and greater than the first pressure value p11 is set.

As in 3 c) can be seen through the actuation current I1 of the first clutch actuation valve, the first clutch actuation valve is at least partially opened from time t1 to time t4 and thus in the first and second step for hydraulically connecting the system pressure branch to the clutch pressure branch. The system pressure valve is open during this and also before and after the first and second step. The system pressure is increased by increasing the pump speed np, as in 3d) to see increased.

In a third step S3, which immediately follows the first step S1 and immediately precedes the second step S2, the target system pressure pt is set to be constant over a third time period Δt3. As a result, the pressure dynamics of the actual system pressure pa arising from the first step S1 can be reduced. The pressure fluctuations in the system pressure branch are reduced.

If the first clutch is operated in a slipping manner during the first step S1, limiting the increase in the system setpoint pressure pt in the first step S1 to the first system setpoint pressure value pt1 can result in a dynamic of the actual system pressure pa and the first clutch pressure p1 and thus also an increase D in the first clutch pressure p1 reduce.

reference list

10

hydraulic device

12

first clutch

14

second clutch

16

Double coupling

18

system pressure branch

20

first clutch pressure branch

22

first check valve

24

first clutch actuation valve

26

second clutch pressure branch

28

second check valve

30

second clutch actuation valve

32

fluid storage

34

first actuator

36

second actuator

38

pressure supply unit

40

suction filter

42

high pressure connection

44

tandem pump unit

46

cooling branch

48

low pressure connection

50

electric motor

52

first cooling branch

54

second cooling branch

56

third cooling branch

58

fluid cooler

60

system pressure valve

62

slider

64

Connection

66

Connection

68

Connection

70

adjusting force

72

pressure side

74

actuation side

76

procedure

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102019130158 [0002]

Claims (10)

Method (76) for controlling a hydraulic device (10) having a system pressure branch (18) in which a system pressure is present, at least one first clutch actuating valve (24) effective between the system pressure branch (18) and a clutch pressure branch (20) in which a clutch pressure ( p1) for actuating a first clutch (12), characterized in that the clutch pressure (p1) is increased above the system pressure (pa) initially set below the clutch pressure (p1) by increasing the system pressure (pt ) using a first pressure gradient (G1) within a first period of time (Δt1) up to a first system pressure value (pt1), which is a first pressure difference (Δp1) below a first pressure value (p11) of the applied clutch pressure (p1) and in a subsequent second step (S2) using at least one compared to the first pressure gradient (G1) smaller second pressure gradient (G2) within a second Ze it range (Δt2) is set greater than the first system pressure value (pt1) and greater than the first pressure value (p11). Method (76) according to claim 1 , characterized in that the first clutch actuation valve (24) in the first and/or second step (S1, S2) for hydraulically connecting the system pressure branch (18) to the clutch pressure branch (20) is at least partially open. Method (76) according to claim 1 or 2 , characterized in that in a third step (S3) immediately following the first step (S1) and immediately preceding the second step (S2), the system pressure (pt) is set constant over a third period of time (Δt3). Method (76) according to claim 3 , characterized in that the third period of time (Δt3) is less than the second period of time (Δt2). Method (76) according to one of the preceding claims, characterized in that the second pressure gradient (G2) is constant within the second period of time (Δt2). Method (76) according to one of the preceding claims, characterized in that the clutch pressure (p1) is set independently of the system pressure (pt) before initiating the first step (S1). Method (76) according to one of the preceding claims, characterized in that the first clutch (12) is operated in a slipping manner at least when the first step (S1) is initiated. Method (76) according to one of the preceding claims, characterized in that the first pressure difference (Δp1) is defined as a function of the first pressure gradient (G1). Method (76) according to one of the preceding claims, characterized in that the system pressure (pt) is provided by a pressure supply unit (38) which can be switched between a first and second operating mode, the first operating mode upon initiation of the first step (S1) is set and the second mode of operation provides a pressurized supply for cooling. Method (76) according to claim 9 , characterized in that an increase in the clutch pressure (p1) by the system pressure (pa) is limited to the first operating mode.

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