Method for controlling hydraulic assembly

Abstract

The invention relates to a method for controlling a hydraulic assembly (1) comprising: a pump (5) rotationally driven by an electric motor (6) and providing a system pressure (p) of a pressure line (8) filled with hydraulic fluid; a pressure control valve (25) that controls the system pressure (p); and at least one pressure-actuated functional component (9, 10), which is integrated into the pressure line (8). In order to detect and optionally compensate for a flow force in the pressure control valve (25) without additional hydraulic components, a volumetric flow (I (V)) through the pressure control valve (25) is estimated as a function of a pump volumetric flow (I (P)) delivered by the pump (5) and a volumetric requirement (V (1), V (2)) in the pressure line (8).

Description

Field of the Invention

[0001] The present invention relates to a method for controlling a hydraulic component, which includes: a pump that is rotationally driven by an electric motor and provides a system pressure for a pressure line filled with a hydraulic fluid; a pressure control valve that controls the system pressure; and at least one pressure-actuated functional component integrated into the pressure line. Background Art

[0002] A method for controlling an electric pump used in a hydraulic system, such as a hydraulic component including a pump rotationally driven by an electric motor, is known from the publication WO 2022 / 012711 A1. The pump provides a system pressure for a separating clutch that separates two driveline components of a motor vehicle and a parking lock for the motor vehicle. The functional components for actuating the separating clutch and the parking lock are designed as slave cylinders. The system pressure is set by means of a pressure control valve.

[0003] A hydraulic system including a pump rotationally driven by an electric motor is known from the publication DE 10 2019 122 694 A1. The hydraulic system sets the system pressure in a hydraulic line and has a device integrated into the hydraulic line for detecting the volume flow rate.

[0004] The object of the present invention is to further develop a method for controlling a hydraulic component. In particular, the object of the present invention is to use this method to determine the volume flow rate through the pressure control valve without providing other hydraulic components for detecting the volume flow rate, and thus to design the hydraulic component simply and cost-effectively. Summary of the Invention

[0005] This object is achieved by the subject matter of claim 1. The claims subordinate to claim 1 propose advantageous embodiments of the subject matter of claim 1.

[0006] The proposed method is used to control a hydraulic component, in particular for actuating a parking lock, disengaging a clutch in a powertrain of a motor vehicle. The clutch is used to disengage and engage powertrain components such as an internal combustion engine and an electric motor, to disengage and engage a drive unit including the internal combustion engine and the electric motor from the rest of the powertrain, etc. The hydraulic component can also be used to cool components of the powertrain using hydraulic fluid. A pump, such as a vane pump, an axial piston pump, a radial piston pump, or advantageously a gear pump, is provided for generating a volumetric flow rate and the resulting system pressure in a pressure line. The pump is rotationally driven by an electric motor, such as a brushless commutated electric motor, which has a corresponding sensor system, such as one or more Hall sensors, for detecting and controlling rotational variables, such as the rotational speed, angular velocity, rotation angle, rotational acceleration, etc. of the rotor, and thus for detecting and controlling the rotational variables of the pump. The system pressure is controlled by a pressure control valve depending on a consumer, such as at least one pressure-actuated functional component, wherein the system pressure is set by correspondingly opening and closing the pressure control valve by discharging the corresponding volumetric flow rate of the hydraulic valve into a pressureless reservoir.

[0007] The volumetric flow rate is estimated by a pressure control valve according to the inventive concept based on the pump volumetric flow rate delivered by the pump and the volumetric requirements in the pressure line. The estimated volumetric flow rate can be used for improved control of the pressure control valve, since the flow force generated by the volumetric flow rate can be estimated and compensated by the pressure control valve, such that the flow-pressure characteristic of the pressure control valve depending on the volumetric flow rate can be controlled in an improved manner.

[0008] The pump volumetric flow rate generated by the pump, which is appropriately controlled by means of a central control unit, is continuously determined based on at least one rotational variable of the electric motor, the displacement of the pump, and the efficiency of the pump. The efficiency can be determined in a simple and approximate manner. It can be assumed that the pressure at the pump is constant, or the influence of pressure on the efficiency can be neglected. Thus, the efficiency can be determined only based on the temperature of the pump or a variable determined for this purpose and the rotational variables of the electric motor, such as the rotational speed of the rotor of the electric motor. Corresponding characteristic curves, characteristic diagrams, or mathematical equations reflecting the performance efficiency can be stored in the central control unit based on the rotational variables and temperature and, if necessary, pressure, and read out and calculated if necessary to determine the efficiency and, if necessary, adapt to the changing conditions of the hydraulic component.

[0009] At least one rotational variable of an electric motor continuously recorded to determine displacement can be, for example, the rotational speed, angular velocity, angular acceleration, etc. of one or more Hall sensors, which are used, for example, for commutation and control of the electric motor. The rotational speed of the pump is determined by the rotational variable. The rotational variable for determining the rotational movement of the pump can also be determined without sensors, for example, based on the measured current and / or the commutation specifications for operating the electric motor. Any transmission ratio set between the rotor of the electric motor and the pump shaft driven by the rotor is considered. When determining displacement as part of efficiency calculation or separately, substantially constant slip, leakage, and / or similar phenomena present at the pump, as determined by recorded parameters such as temperature, viscosity of the hydraulic fluid, and / or similar parameters, can be determined and considered.

[0010] The volume requirements in the pressure line depend on the individual volume consumption of one or more functional components and the nature of the functions of one or more functional components, as well as any leakage within the pressure line having at least one functional component. For example, all or part of the volume requirements of at least one functional component result from the absorption of the hydraulic fluid during its actuation or the reset after its actuation. For example, at least one functional component can be designed as a slave cylinder, where their volume requirements result at least in part from the stroke, such as the actuation path and piston surface of the slave cylinder piston of the slave cylinder, such that the volume requirements of the slave cylinder can be determined by the effective volume determined by the actuation path of the slave cylinder and the piston surface of the slave cylinder. The actuation path of the slave cylinder, such as the stroke of the slave cylinder piston, can be determined, for example, by means of a path sensor for path-related control of the actuation of the slave cylinder, and thus the actuation of the relevant actuating devices in the driveline, such as the parking lock and / or the disengaging clutch, can be determined by the control unit.

[0011] In addition to the volume requirements of at least one functional component during its actuation, variables considering losses such as leakage of the hydraulic fluid can also be considered to determine the volume flow rate of the pressure control valve. For example, such variables can be estimated based on the temperature, viscosity, aging, and / or other characteristics of the hydraulic fluid and / or the pressure line having at least one functional component, considered as constants, or ignored if necessary.

[0012] For example, the overall volume requirement can be formed as a summation parameter based on the volume requirements of at least one functional component and, if applicable, variables estimating losses of the hydraulic fluid. This summation parameter can be calculated at any time and subtracted from the pump volume flow rate. Then, the obtained result gives the estimated volume flow rate at the pressure control valve. The flow force effect on the pressure control valve can be compensated with this currently estimated volume flow rate. Description of the Drawings

[0013] The present invention will be explained in more detail with reference to an exemplary embodiment in a single drawing. The drawing shows a hydraulic diagram of a possible hydraulic assembly 1 for implementing the proposed method in a schematic representation. Detailed Description of the Invention

[0014] The hydraulic assembly 1 is divided into a pump unit 2, a hydraulic section 3, and a control unit 4. The pump unit 2 includes a pump 5 that is rotationally driven by the rotor of an electric motor 6. A sensor 7, for example one or more Hall sensors, is used to record the rotational variables of the rotor. The electric motor 6 can be controlled by the control unit 4 and the power electronics unit using the recorded rotational variables.

[0015] For example, the pump 5 is designed as a gear pump and sucks a hydraulic fluid, such as hydraulic oil, from an unpressurized reservoir 24, where a filter unit 23 is connected between the pump and the reservoir. The displacement V(P) and the efficiency η of the pump 5 are known or continuously determined. The displacement and efficiency depend, for example, on the temperature of the pump 5, the viscosity of the hydraulic fluid, the slip of the hydraulic fluid, and the leakage of the hydraulic fluid. The pump volume flow rate I(P) discharged into the pressure line 8 of the hydraulic section 3 is continuously determined by the rotational variables of the sensor 7, such as the rotational speed n of the rotor and the displacement V(P).

[0016] Two hydraulic active functional components 9, 10 are integrated into the pressure line 8, and these functional components require volume requirements V(1) and V(2) for operation. The functional component 9 actuates, for example, a parking lock by means of a slave cylinder 11. The actuation path s of the slave cylinder piston 12 of the slave cylinder 11 during its actuation is detected by a path sensor 13. The volume requirement V(1) is obtained by the product of the actuation path s and the piston surface F of the slave cylinder piston 12. A latching mechanism 14 holds the parking lock in its open and closed positions accordingly. For this purpose, an electric switching valve 15 is provided to enable the latching mechanism 14, and a hydraulic cylinder 16 switched by a valve 17 is provided to deactivate the latching mechanism. If necessary, the volume requirement of the cylinder 16 is considered. Once the latching mechanism 14 is deactivated by the valve 17, the slave cylinder 11 is actuated by a switching valve 18.

[0017] For example, the functional component 10 is used to actuate a disengaging clutch and is only shown in block diagram form. These are actuated by a switching valve 19, which controls the slave cylinder by means of hydraulic fluid guided in lines 20, 21, and the actuation path of which is detected by a path sensor 22, so that the volume requirement V(2) can be determined based on the surface of the slave cylinder piston of the slave cylinder and the detected actuation path.

[0018] The system pressure p in the pressure line 8 is set by means of a pressure control valve 25, which is opened accordingly and connected to the reservoir 24, where a heat exchanger 26 is connected between the pressure control valve and the reservoir to cool the outflowing hydraulic fluid.

[0019] The control unit 4 controls the electric motor 5, the valves 17, 18, 19, the electric switching valve 15 and the pressure control valve 25 using a simplified electrical connection 27, and records the measurement signals from the sensors 7 and the path sensors 13, 22.

[0020] In order to estimate the volume flow rate I(V) flowing through the pressure control valve 25, taking into account the volume requirements of the pressure line 8, the pump volume flow rate I(P) is preferably determined currently and continuously, for example to estimate the flow force effects mainly at the pressure control valve 25 and to compensate for them if necessary. As a good approximation, the volume requirements of the pressure line include the volume requirements V(1) of the functional component 9, the volume requirements V(2) of the functional component 10 and the variable G assumed in terms of volume dimensions if necessary, where additional volume requirement components can be recorded, such as leaks in the pressure line 8, the volume requirements of the cylinder 16, etc. In the simplest case, the volume requirements of the pressure line 8 are subtracted from the pump volume flow rate I(P) according to the following equation with the variables listed above to estimate the volume flow rate I(V) in the control unit 4:

[0021] I(V) = I(P) – (V(1) + V(2) + G))

[0022] List of reference signs

[0023] 1 Hydraulic assembly

[0024] 2 Pump unit

[0025] 3 Hydraulic section

[0026] 4 Control unit

[0027] 5 Electric motor

[0028] 6 Pump

[0029] 7 Sensor

[0030] 8 Pressure line

[0031] 9 Functional component

[0032] 10 Functional component

[0033] 11 Driven cylinder

[0034] 12 Driven cylinder piston

[0035] 13 Path sensor

[0036] 14 Latching mechanism

[0037] 15 Switching valve

[0038] 16 Cylinder

[0039] 17 Valve

[0040] 18 Valve

[0041] 19 Valve

[0042] 20 Pipeline

[0043] 21 Pipeline

[0044] 22 Path Sensor

[0045] 23 Filter Unit

[0046] 24 Storage Tank

[0047] 25 Pressure Control Valve

[0048] 26 Heat Exchanger

[0049] 27 Connector

[0050] F Piston Surface

[0051] I(P) Pump Volume Flow Rate

[0052] I(V) Volume Flow Rate

[0053] n Rotation Speed

[0054] p System Pressure

[0055] s Actuation Path

[0056] V(P) Displacement

[0057] V(1) Volume Requirement

[0058] V(2) Volume Requirement

[0059] η Efficiency

Claims

1. A method for controlling a hydraulic component (1), the hydraulic component having: a pump (5) which is rotationally driven by an electric motor (6) and provides a system pressure (p) for a pressure line (8) filled with hydraulic fluid; a pressure control valve (25) which controls the system pressure (p); and at least one pressure-actuated functional component (9, 10) which is integrated into the pressure line (8), characterized in that, The volume flow rate (I(V)) through the pressure control valve (25) is estimated based on the pump volume flow rate (I(P)) delivered by the pump (5) and the volume requirements (V(1), V(2)) in the pressure line (8).

2. The method according to claim 1, characterized in that, The pump volume flow rate (I(P)) is determined by at least one rotational variable of the electric motor (6), the displacement (V(P)) of the pump (5), and the efficiency (η) of the pump.

3. The method according to claim 2, characterized in that, The rotational variable is the rotational speed (n) or angular velocity of the rotor of the electric motor (6).

4. The method according to claim 2 or 3, characterized in that, The pump volume flow rate (I(P)) is determined based on temperature.

5. The method according to any one of claims 1 to 4, characterized in that, At least one functional component (9, 10) is designed as a slave cylinder (11), and the volume requirements (V(1), V(2)) are determined at least in part based on the actuation path (s) and piston surface (F) of the slave cylinder piston (12) of the slave cylinder (11).

6. The method according to claim 5, wherein The actuation path (s) of the slave cylinder piston (12) is determined based on path sensors (13, 22).

7. The method according to claim 5 or 6, characterized in that, The at least one functional component (9, 10) is designed as a slave cylinder (1) for actuating a parking lock and / or a slave cylinder for actuating a disengaging clutch of a powertrain component of a motor vehicle.

8. The method according to any one of claims 1 to 7, characterized in that The volume flow rate (I(V)) is additionally determined based on a variable (G) for estimating leakage of the hydraulic fluid.

9. The method according to any one of claims 1 to 8, characterized in that The volume requirements (V(1), V(2)) of the at least one functional component (9, 10) and optionally the variable (G) for estimating leakage of the hydraulic fluid are formed in real time as summation parameters, and the summation parameters are subtracted from the pump volume flow rate (I(P)) to form the current volume flow rate (I(V)) at the pressure control valve (25).

10. The method according to any one of claims 1 to 9, characterized in that, The flow force influence on the pressure control valve is compensated by means of the volume flow rate (I(V)) through the pressure control valve (25).

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