DE102021124216B3 - Hydraulic device and method for operating a hydraulic device - Google Patents

Abstract

The invention relates to a method (42) for operating a hydraulic device (10) which, on the one hand, supplies an actuating device (12) for actuation with a fluid pressure and, on the other hand, a supply device (14) for cooling and/or lubrication with a fluid flow, the hydraulic device ( 10) has a pump (18) which is operated alternately between a supply operation for operating the supply device (14) and an actuation operation for operating the actuation device (12), a target speed value (n) of the pump (18) for an upcoming actuation operation being dependent is set by a pump supply speed (nc) of the pump (18) present in the cooling operation immediately before. The invention also relates to a hydraulic device (10).

Description

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

DE 10 2019 203 239 A1 and WO 2021 175 366 A1 discloses methods of operating pumps for hydraulic systems.

A hydraulic device is for example in DE 10 2020 125 635 A1 described, which has an actuating device with at least one hydraulically actuatable actuating element for actuating a clutch and a hydraulically operated cooling device for cooling. A fluid pressure for actuation and a fluid volume flow for cooling is provided by a pump which is operated alternately between a cooling operation for operating the cooling device and an actuating operation for operating the actuating device.

The object of the present invention is to operate the hydraulic device in a more energy-saving, efficient and cost-effective manner. The speed of the pump should be maintained as much as possible.

At least one of these objects is solved by a method having the features of claim 1. As a result, the hydraulic device can be operated more efficiently, more energy-efficiently and more cost-effectively. The speed changes of the pump when switching between the actuating operation and the cooling operation can be reduced.

The hydraulic device can be arranged in a drive train of a vehicle, in particular a motor vehicle.

The actuating device can be provided for actuating a clutch or a brake. The clutch or brake can be effective in an e-axle with power shift capability. The E-axis can have at least two switchable gear ratios. The clutch may transmit torque dependent on fluid pressure at the actuator. The brake can support a torque dependent on a fluid pressure at the actuating device in a fixed manner in the housing.

The supply device can bring about cooling and/or lubrication of the clutch and/or other components.

The pump can be driven electrically. An electric motor can be assigned to the pump. The pump can be driven by the electric motor, preferably in both the supply mode and the actuation mode. As a result, the pump speed can be independent of mechanical speeds, for example in a gearbox.

The hydraulic device can have at least one check valve. The check valve can be associated with the clutch or the brake. The check valve can be arranged between the pump and the clutch or the brake.

Alternating switching between the cooling mode and the actuating mode can also be necessary when the fluid pressure has built up to actuate the actuating device, for example because of a required pressure increase that builds up the fluid pressure that is decreasing due to fluid leaks in the hydraulic device.

In a preferred embodiment of the invention, it is advantageous if the target speed value is set at least to a speed value that corresponds to the pump supply speed. This allows the pump to be operated at least at the pump supply speed, further reducing the speed changes of the pump.

The target speed value can also be set to a speed value that is higher than the pump supply speed. This can be necessary, for example, when the fluid pressure that can be achieved by the pump operated at the pump supply speed is insufficient for the actuation operation.

In a special embodiment of the invention, it is advantageous if the target speed value is calculated as a function of a first condition including the pump supply speed. The first condition can still occur during the supply operation and can preferably be queried before the actuation operation.

In a specific embodiment of the invention, it is advantageous if the first condition is preceded by a conversion in which an actuating speed value of the pump required for the actuating operation is calculated as a function of an actuating target pressure required during the actuating operation and the first condition is used to check whether the Actuate speed value is less than pump supply speed. The actuation speed value can correspond to a pump speed of the pump that builds up the actuation setpoint pressure. The conversion between the specified target actuation pressure and the actu The speed value can be performed analytically, numerically, and/or through a lookup table.

In an advantageous embodiment of the invention, it is provided that the first condition is preceded by a conversion in which an actuating pressure that can be achieved by the current pump supply speed is calculated for the pending actuating operation and the first condition is used to check whether the actuating pressure that can be achieved is greater than one in the Actuating operation is the required actuating target pressure for the upcoming actuating operation. The conversion between the pump supply speed and the actuation pressure that can be achieved can be carried out analytically, numerically and/or by means of a look-up table.

A preferred embodiment of the invention is advantageous in which a pressure hysteresis value is included in the first condition and the first condition is used to check whether the achievable actuating pressure is greater than the sum of the actuating setpoint pressure and the pressure hysteresis value. As a result, the switching frequency between the operating mode and the supply mode can be reduced. The pressure hysteresis value can be constant or variable.

In a preferred embodiment of the invention, it is provided that the pressure hysteresis value for the next query of the first condition within the scope of the current query is calculated and defined as the difference between the actuation pressure that can be achieved and the actuation setpoint pressure. The pressure hysteresis value can be saved for the next query of the first condition. The larger the pressure hysteresis value is, the more the number of switching operations between the supply mode and the actuation mode can be reduced.

In a preferred embodiment of the invention, it is provided that as soon as the first condition is met, the target speed value is set to a speed value that corresponds to the pump supply speed. This allows the pump supply speed to provide the desired actuation pressure to remain adjusted during actuation operation.

In a preferred embodiment of the invention, it is advantageous that as soon as the first condition is not met, the target speed value is set to an actuation speed value that is higher than the pump supply speed. As a result, the required actuation pressure can be built up during the actuation operation.

In a special embodiment of the invention, it is advantageous if the target pump speed is calculated as a function of at least one additional parameter. The additional parameter can be a temperature of the actuating device and/or of a hydraulic fluid.

Furthermore, at least one of the objects specified above is achieved by a hydraulic device having the features according to claim 10. As a result, the hydraulic device can be designed more cost-effectively and can be operated more efficiently and with less energy consumption.

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: Ein Verfahren zum Betrieb der Hydraulikvorrichtung aus 1 in einer speziellen Ausführungsform der Erfindung.
• 3: Ein Verfahren zum Betrieb der Hydraulikvorrichtung aus 1 in einer weiteren 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 method of operating the hydraulic device 1 in a specific embodiment of the invention.
• 3 : A method of operating the hydraulic device 1 in another specific embodiment of the invention.

1 shows a hydraulic device in a special embodiment of the invention. The hydraulic device 10 can be arranged in a vehicle and supply an actuating device 12 for actuation with a fluid pressure and a supply device 14 for cooling and/or lubrication with a fluid flow. The actuating device 12 is provided in particular for actuating a clutch 16 . Depending on the fluid pressure at the actuating device 12, the clutch 16 can transmit a torque, for example between a drive element, in particular an electric motor, and a driven element, in particular at least one vehicle wheel.

The hydraulic device 10 includes a pump 18 which is connected to the actuating device 12 and the supply device 14 via fluid lines 20 . The actuating device 12 is connected via a clutch actuating valve 22 and a check valve 24 to a common fluid line 26 which is connected to further consumers, for example a further actuating device of a further clutch, preferably via a further check valve 28 . Between the clutch actuation valve 22 and the A spring-loaded accumulator 30 is arranged in the check valve 24, via which possible fluid leaks, which can lead to a pressure reduction in the fluid pressure at the actuating device 12, are compensated for.

The common fluid line 26 is connected to a first connection 32 of the pump 18 . The cooling device is connected to a second connection 34 of the pump 18 . A system pressure valve 36 is arranged between the first and second connection 32, 34, via which the fluid pressure in the common fluid line 26 is controlled.

The pump 18 is connected to a fluid reservoir 38 . An electric motor 40 drives the pump 18 and depending on the speed provided by the electric motor 40, the pump 18 has a pump speed to apply fluid flow and/or fluid pressure. The pump 18 can be operated alternately between a supply mode for operating the supply device 14 and an actuating mode for operating the actuating device 12 .

2 shows a method for operating the hydraulic device 1 in a specific embodiment of the invention. Method 42 is carried out when the hydraulic device is in operation, for example when the vehicle in which the hydraulic device is arranged is in operation. With the method 42, the hydraulic device can be switched between the actuation mode and the supply mode. Since the fluid pressure may decrease due to fluid leakage in the hydraulic device, the actuation operation is required at times to increase the fluid pressure at the actuator and ensure actuation.

Assuming supply operation, in which the pump is operated at a pump supply speed n _c , a target speed value n of the pump for the subsequent actuation operation is set as a function of the applied pump supply speed n _c . First, a conversion 44 takes place, in which an actuation speed value n _b of the pump required for the actuation operation is calculated as a function of an actuation setpoint pressure p _b required for the actuation operation. The target actuation pressure p _b is preferably predetermined. The conversion 44 is carried out, for example, analytically, numerically and/or using a lookup table and can include further parameters a, for example a temperature of the actuating device and/or a hydraulic fluid.

In a subsequent query 46 of a first condition 48, a comparison is made between the actuating speed value n _b and the present pump supply speed n _c as follows $$n_b<n_c$$

If the first condition 48 is met, ie the actuating speed value n _b is less than the pump supply speed n _c , then in a subsequent step 50 the target speed value n is set equal to the pump supply speed n _c . As a result, a speed change at the pump can be avoided as far as possible even when switching between the supply mode and the actuation mode. As a result, the pump and the hydraulic device can be operated more efficiently and with less energy consumption.

If the first condition 48 is not met, i.e. the actuation speed value n _b is equal to or greater than the pump supply speed n _c , then in a subsequent step 52 the target speed value n is set to the actuation speed value n b , which is higher than the pump supply speed n _c , which is _higher in the subsequent actuation operation applies the actuating pressure required to actuate or maintain actuation.

3 shows a method for operating the hydraulic device 1 in another specific embodiment of the invention. Method 42 can be added as an extension to 1 be applied. A conversion 44 calculates the actuating pressure p′ _b that can be achieved in a subsequent actuating operation as a function of the present pump supply speed n _c . In the conversion 44, further parameters a, such as a temperature of the actuating device and/or a hydraulic fluid, can be included.

In a subsequent query 46 of a first condition 48, a comparison is made between the achievable actuating pressure _p'b and the actuating pressure required for the actuation as follows $$p{\text{'}}_b>p_b+p_H$$

In this case, a pressure hysteresis value _ph is specified for query 46 of first condition 48 .

If the first condition 48 is met, i.e. the achievable actuating pressure _p'b is greater than the sum of the actuating setpoint pressure _pb and the pressure hysteresis value _ph , then in a subsequent step 50 the target speed value n is set equal to the pump supply speed _nc . As a result, the pump and the hydraulic device can be operated more efficiently and with less energy consumption and the number of switching operations between the supply mode and the actuation mode can be reduced.

In step 50, the pressure hysteresis value _ph to be used for the next query 46 of the first condition 48 is calculated and stored as the difference between the achievable actuating pressure p′ _b and the actuating setpoint pressure p _b .

If the first condition 48 is not met, i.e. the achievable actuating pressure p' _b is less than or equal to the sum of the target actuating pressure p _b and the pressure hysteresis value _ph , then in a subsequent step 52 the target speed value n is set to that compared to the pump supply speed n _c higher actuation speed value n _b , which applies the actuation pressure required for actuation or maintenance of actuation during the subsequent actuation operation. The specified pressure hysteresis value _ph remains unchanged.

The actuation speed value n _b is calculated from the actuation setpoint pressure p _b by means of an upstream further conversion 54 . The further conversion 54 can include further parameters a that have already been used in the conversion 44, for example.

Reference List

10

hydraulic device

12

operating device

14

supply device

16

coupling

18

pump

20

fluid line

22

clutch actuation valve

24

check valve

26

fluid line

28

another check valve

30

spring accumulator

32

first connection

34

second connection

36

system pressure valve

38

fluid storage

40

electric motor

42

procedure

44

conversion

46

query

48

first condition

50

Step

52

Step

54

further conversion

n

target speed value

nb

actuation speed value

nc

pump supply speed

p'b

achievable operating pressure

p.b

actuation target pressure

Ph

pressure hysteresis value

a

parameter

Claims (10)

Method (42) for operating a hydraulic device (10), which on the one hand supplies an actuating device (12) for actuation with a fluid pressure and on the other hand a supply device (14) for cooling and/or lubrication with a fluid flow, the hydraulic device (10) having a pump (18) which is operated alternately between a supply mode for operating the supply device (14) and an actuation mode for operating the actuation device (12), characterized in that a target speed value (n) of the pump (18) for a pending actuation mode depends on a pump supply speed (n _c ) of the pump (18) present immediately before in the cooling mode. Method (42) according to claim 1 , characterized in that the target speed value (n) is set at least to a speed value corresponding to the pump supply speed (n _c ). Method (42) according to claim 1 or 2 , characterized in that the target speed value (n) is calculated as a function of a first condition (48) involving the pump supply speed (n _c ). Method (42) according to claim 3 , characterized in that the first condition (48) is preceded by a conversion (44) in which an actuation speed value (n _b ) of the pump (18) required for the actuation operation is calculated as a function of a target actuation pressure (p _b ) required for the actuation operation and the first condition (48) checks whether the actuation speed value (n _b ) is less than the pump supply speed (n _c ). Method (42) according to claim 3 , characterized in that the first condition (48) a conversion (44) is preceded, in which an actuating pressure (p' _b ) that can be achieved by the present pump supply speed (n _c ) is calculated for the pending actuating operation, and the first condition (48) is used to check whether the achievable actuating pressure (p' _b ) is greater than an actuation set pressure (p _b ) required for the actuation operation at the pending actuation operation. Method (42) according to claim 3 , characterized in that the first condition (48) is preceded by a conversion (44) in which an actuating pressure (p' _b ) that can be achieved by the present pump supply speed (n _c ) is calculated for the pending actuating operation and in the first condition (48 ) a pressure hysteresis value ( _ph ) is included and the first condition (48) is used to check whether the achievable actuation pressure (p' _b ) is greater than the sum of the desired actuation pressure (p _b ) and the pressure hysteresis value ( _ph ). Method (42) according to claim 6 , characterized in that the pressure hysteresis value ( _ph ) for the next query of the first condition (48) within the scope of the current query is calculated and defined as the difference between the achievable actuating pressure (p' _b ) and the actuating setpoint pressure (p _b ). Method (42) according to one of claims 3 until 7 , characterized in that as soon as the first condition (48) is met, the target speed value (n) is set to a speed value corresponding to the pump supply speed (n _c ). Method (42) according to one of claims 3 until 8th , characterized in that as soon as the first condition (48) is not met, the target speed value (n) is set to an actuating speed value (n _b ) which is higher than the pump supply speed (n _c ). Hydraulic device (10) for supplying an actuating device (12) for actuation with a fluid pressure and a supply device (14) for cooling and/or lubrication with a fluid flow, the hydraulic device (10) having a pump (18) which alternates between a supply operation for operating the supply device (14) and an actuating operation for operating the actuating device (12) and the hydraulic device (10) is set up to carry out the method (42) according to one of the preceding claims.

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