Method, system and computer program product for controlling at least one electrically driven hydraulic pump of a hydraulic chassis of a motor vehicle.

Abstract

Method for controlling at least one electrically driven hydraulic pump (7, 8) of a hydraulic suspension (20) of a motor vehicle, which is driven, among other things, at different speeds, accelerations and on different surfaces, wherein operational driving situations arise in which the hydraulic suspension (20) is subjected to a greater or lesser load, wherein the electrically driven hydraulic pump (7, 8) is selectively controlled by a variable control method (22) depending on a currently detected and / or recognized load of the hydraulic suspension (20), characterized in that in the variable control method (22) switching between different modulation types is performed depending on at least one of the following parameters: Vehicle speed (31), acceleration (32) in a longitudinal direction of the vehicle, acceleration in a transverse direction of the vehicle, road surface condition (33).

Description

[0001] The invention relates to a method, a system and a computer program product for controlling at least one electrically driven hydraulic pump of a hydraulic chassis of a motor vehicle, which is driven, among other things, at different speeds, accelerations and on different surfaces, wherein operational driving situations arise in which the hydraulic chassis is subjected to more or less heavy loads.

[0002] German patent application DE 10 2006 027 713 A1 discloses a method for calculating the current control signals for controlling a machine located in a vehicle, wherein the method comprises: determining an operating range of the machine based on the voltage limit of an inverter in the machine; determining a current reference signal for controlling the torque of the machine based on the determined operating range, wherein the calculation of the current reference signal includes the use of one of several equations that optimize the current reference signal based on the determined operating range; and applying the current control signals to the machine based on the calculated current reference signal. German patent application DE 10 2021 131 845 A1 discloses the control of an electric traction machine of a vehicle, wherein the control can be carried out by means of space vector modulation or discontinuous pulse width modulation.the selection is made based on driving data. German patent application DE 10 2020 131 509 A1 discloses a method for controlling an inverter in a motor vehicle, wherein the inverter converts a DC voltage from an electrical energy source of the motor vehicle into an AC voltage and outputs it to an electric machine, the method comprising the following steps: receiving a user selection; adapting a modulation method used by the inverter to convert the DC voltage into the AC voltage depending on the user selection, wherein the modulation method used is selected from the following modulation methods: continuous pulse width modulation via sinusoidal pulse width modulation, sinusoidal pulse width modulation with injection of a third harmonic or space vector modulation, each with asynchronous or synchronous and constant or variable clock frequency.as well as discontinuous or discrete pulse-width modulation at constant or variable clock frequency, block commutation and direct self-regulation via a hysteresis controller or direct self-regulation in combination with a pulse-width modulation method. U.S. patent application US 2018 / 0326810A1 discloses a suspension device comprising: a telescopic movable actuator; a pump; a fluid pressure circuit provided between the actuator and the pump, supplying fluid dispensed by the pump to the actuator, causing the actuator to expand and contract; and a controller that controls the drive of the pump, the controller comprising a preview sensor provided in a vehicle that detects a displacement of a road surface ahead of the vehicle; a unit for sensing a road surface condition index, which obtains a road surface condition index,which corresponds to a measure of the roughness of the road surface, based on the road surface displacement detected by the preview sensor in front of the vehicle; and a unit for determining the target speed, which determines a target speed of the pump based on the road surface condition index. German patent application DE 10 2006 032 893 A1 discloses a motor vehicle system with at least one actuator designed as an electric motor, a control unit for controlling the at least one actuator, wherein the control is effected by modulating the actuator supply voltage, and wherein the control unit is designed such thatthat during a first actuator operating mode, the control of the at least one actuator is carried out in a first modulation mode, and during a second actuator operating mode, the control of the at least one actuator is carried out in a second modulation mode. German patent application DE 10 2015 214 839 A1 discloses a method for the discrete-time control of an electronically commutated electric motor, in particular an electric drive motor of a motor vehicle, using a discrete-time modulation method, wherein a control frequency and a modulation frequency are set separately from each other. German patent application DE 10 2020 131 509 A1 discloses a method for controlling an inverter in a motor vehicle, wherein the inverter converts a DC voltage from an electrical energy source of the motor vehicle into an AC voltage and outputs it to an electric machine.wherein the method comprises the following steps: receiving a user selection; adapting a modulation method used by the inverter to convert the DC voltage into the AC voltage depending on the user selection, wherein the modulation methods use pulse width modulation, wherein the modulation method used is selected from the following modulation methods: continuous pulse width modulation via sine pulse width modulation, sine pulse width modulation with injection of a 3rd harmonic or space vector modulation, each with asynchronous or synchronous and constant or variable clock frequency, as well as discontinuous or discrete pulse width modulation at constant or variable clock frequency, block commutation and direct self-regulation via a hysteresis controller or direct self-regulation in combination with a pulse width modulation method.

[0003] The object of the invention is to make the control of an electrically driven hydraulic pump of a hydraulic chassis of a motor vehicle as energy-efficient as possible.

[0004] The problem is solved by a method with the features of claim 1. Thus, the electrically driven hydraulic pump can be controlled very energy-efficiently during relatively steady-state operation of the vehicle, for example, when driving a long stretch of highway at a relatively constant speed. When required, the electrically driven hydraulic pump can also be controlled with high dynamics during more sporty operation of the vehicle, for example, when driving on a racetrack. In this way, energy can be effectively saved with relatively simple means, without noticeably impairing the function of the hydraulic suspension during vehicle operation.

[0005] A preferred embodiment of the method is characterized in that the variable control method switches between space vector modulation and discontinuous pulse width modulation. Space vector modulation is also known as space vector modulation. The different modulation types are known per se.

[0006] Another preferred embodiment of the method is characterized in that the variable control method switches to block commutation when required. This control variant is also known per se. By switching between the individual modulation types, the hydraulic pump of the hydraulic suspension can be operated in an overall energy-efficient manner.

[0007] Another preferred embodiment of the method is characterized in that the electrically driven hydraulic pump is controlled by space vector modulation during comfort-oriented operation of the vehicle on a smooth road below a certain speed. In this operating mode, wheel and body accelerations are relatively low. This operating mode is, for example, a normal driving mode in which low lateral and longitudinal accelerations of the vehicle occur.

[0008] Another preferred embodiment of the method is characterized in that the electrically driven hydraulic pump is controlled by discontinuous pulse width modulation during comfort-oriented operation of the vehicle above the limit speed. The limit speed can be preset or selected. With the chosen control variant, the acoustics during operation of the hydraulic suspension can be particularly advantageously optimized.

[0009] Another preferred embodiment of the method is characterized in that the electrically driven hydraulic pump is controlled by discontinuous pulse-width modulation during comfort-oriented operation of the vehicle on an uneven road above the limiting speed, with a switch to block commutation occurring in a high load and speed range. This improves the function of the hydraulic suspension under high wheel and body accelerations. The vehicle is operated, for example, in a normal driving mode in which relatively low lateral and longitudinal accelerations occur.

[0010] Another preferred embodiment of the method is characterized in that the electrically driven hydraulic pump is controlled by discontinuous pulse width modulation during sporty operation of the vehicle on a smooth road above a certain speed, with a switch to block commutation occurring in a high load and speed range. The vehicle is operated, for example, in a sport mode or a sport plus mode, in which high lateral and longitudinal accelerations occur, particularly on a racetrack.

[0011] In a system for controlling an electrically driven hydraulic pump of a motor vehicle's hydraulic suspension according to a previously described method, the problem stated above is solved alternatively or additionally by combining the electrically driven hydraulic pump with a control logic that switches between at least two different control variants depending on the current driving situation. The claimed system advantageously comprises an actuator unit in which the hydraulic pump is combined with an electric motor and an electronic control unit for the electric motor. Particularly advantageously, two electrically driven hydraulic pumps per axle of the motor vehicle are combined in the actuator unit.

[0012] The invention further relates to a computer program product, particularly in an actuator device, comprising commands which, when the computer program is executed by a computing device, cause the computing device to execute a previously described method. The computer program product is advantageously used in the actuator device in which an electric motor, used to drive an electrically driven hydraulic pump in a hydraulic chassis, is controlled by a suitable electronic control system.

[0013] Further advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are described in detail with reference to the drawing. The drawing shows: Fig. 1. A schematic representation of a method for controlling at least one electrically driven hydraulic pump of a hydraulic chassis of a motor vehicle; and Fig. 2 a schematic representation of an axle of a motor vehicle with a hydraulic actuator.

[0014] In Fig. Figure 2 shows two wheels 1, 2 of an axle of a motor vehicle, indicated only by two circles. Rectangles indicate two hydraulic dampers 3, 4, which are assigned to the two wheels 1, 2. The hydraulic dampers 3, 4, in combination with a hydraulic actuator 5, serve to represent a system 10 for active damping control during the operation of the motor vehicle.

[0015] The hydraulic actuator assembly 5 comprises two hydraulic pumps 7, 8, which can be controlled separately via a common electrical control unit 6. Hydraulic pump 7 is hydraulically connected to the hydraulic damper 3, also referred to simply as the damper, via hydraulic lines 11, 12. Similarly, hydraulic pump 8 is hydraulically connected to the damper 4 via hydraulic lines 13, 14.

[0016] Fig. Figure 1 illustrates an axle of a hydraulic suspension 20 of a motor vehicle, which comprises at least two axles. The motor vehicle, not shown further, preferably comprises four wheels, each of which is assigned a hydraulic damper. The hydraulic damper represents a shock absorber in an active suspension of the motor vehicle.

[0017] The hydraulic medium used to operate the hydraulic suspension 20 is preferably a hydraulic fluid, also referred to as hydraulic oil or simply oil. In addition to the hydraulic damper volume, the hydraulic damper advantageously includes a gas accumulator with a compensation volume. The damping control is preferably an active damping control system.

[0018] In Fig. 2. The two electrically driven hydraulic pumps 7, 8 are controlled via a common electrical control unit 6 in the hydraulic actuator 5. Of course, each of the two electrically driven hydraulic pumps 7, 8 can also be assigned a separate electrical control unit.

[0019] In Fig. Figure 1 shows three rectangles representing an input 21, a variable control method 22, and an actuator 23. The actuator 23 is, for example, the hydraulic actuator 5 in Fig. 1.

[0020] The actuator unit 23 includes the hydraulic pump 7. Fig. 1, which is driven by an electric motor 50 (only indicated). The electric motor 50 is controlled by a controller 51 (also only indicated) using the variable control method 22. The variable control method 22 comprises various control variants or modulation types 41 to 45.

[0021] These include, for example, space vector modulation 41, discontinuous pulse width modulation 42, and block commutation 43. Reference numeral 44 illustrates switching between discontinuous pulse width modulation 42 and block commutation 43. Reference numeral 45 denotes another control method not described in detail.

[0022] A double arrow 40 is in Fig. 1 indicates that, within the framework of the variable control procedure 22, switching is made between the different modulation types or control variants 41 to 45 in order to control the electrically driven hydraulic pump 7 in an energy-efficient manner.

[0023] For example, a vehicle speed 31, accelerations 32 and a road surface condition 33 serve as input 21 for the variable control method 22. The vehicle speed 31 varies greatly during the operation of the motor vehicle.

[0024] To optimize the switching processes between the individual control variants 41 to 45, at least one limit speed can be selected or preset. The accelerations 32 include both accelerations in a longitudinal direction of the vehicle, also referred to as longitudinal accelerations, and accelerations in a lateral direction of the vehicle, also referred to as lateral acceleration.

[0025] The road surface condition 33 also varies considerably. In extreme cases, the road surface condition 33 varies between a smooth road surface, for example on a motorway, and a very uneven surface, for example on a dirt road or in an undeveloped or only inadequately developed section of terrain.

[0026] In the variable control method 22, the actuator unit 23 automatically switches between the different control variants or modulation types 41 to 45. This enables energy-efficient operation of the hydraulic suspension system for positioning requirements with low dynamics. At the same time, robust and dynamic control is enabled for positioning requirements with high dynamics.

Claims

[1] Method for controlling at least one electrically driven hydraulic pump (7, 8) of a hydraulic chassis (20) of a motor vehicle which is driven, among other things, at different speeds, accelerations and on different surfaces, wherein operational driving situations arise in which the hydraulic chassis (20) is subjected to a greater or lesser load, wherein the electrically driven hydraulic pump (7, 8) is selectively controlled by a variable control method (22) depending on a currently detected and / or recognized load of the hydraulic chassis (20), characterized by , that in the variable control method (22) switching between different modulation types is performed depending on at least one of the following parameters: Vehicle speed (31), acceleration (32) in a longitudinal direction of the vehicle, acceleration in a transverse direction of the vehicle, road surface condition (33). [2] Method according to claim 1, characterized by , that in the variable control method (22) switching is performed between a space vector modulation (41) and a discontinuous pulse width modulation (42). [3] Method according to claim 2, characterized by , that in the variable control method (22) a switch is made to block commutation (43) if necessary. [4] Method according to claim 2 or 3, characterized by , that the electrically driven hydraulic pump (7,8) is controlled by the space vector modulation (41) in a comfort-oriented operation of the motor vehicle on a smooth road below a limit speed. [5] Method according to claim 4, characterized by, that the electrically driven hydraulic pump (7,8) is controlled by discontinuous pulse width modulation (42) in the comfort-oriented operation of the motor vehicle above the limit speed. [6] Method according to claim 4 or 5, characterized by , that the electrically driven hydraulic pump (7,8) is controlled by discontinuous pulse width modulation (42) in the comfort-oriented operation of the motor vehicle on an uneven road above the limit speed, whereby a switch to block commutation (43) takes place in a high load and speed range. [7] Method according to any one of claims 2 to 6, characterized by, that the electrically driven hydraulic pump (7,8) is controlled by discontinuous pulse width modulation (42) in a sport-oriented operation of the motor vehicle on a smooth road above a limit speed, whereby a switch to block commutation (43) takes place in a high load and speed range. [8] System for controlling an electrically driven hydraulic pump (7, 8) of a hydraulic chassis (20) of a motor vehicle according to a method according to the preceding claims, characterized by , that the electrically driven hydraulic pump (7,8) is combined with a control logic that switches between at least two different control variants depending on the current driving situation. [9] Computer program product, in particular in an actuator device, comprising instructions which, when the computer program is executed by a computing device, cause the computing device to execute a method according to any one of claims 1 to 7.

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