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DE-102025102014-B3 - Method and system for determining the state of a vehicle

DE102025102014B3DE 102025102014 B3DE102025102014 B3DE 102025102014B3DE-102025102014-B3

Abstract

The presented invention relates to a method (100) for determining a state of a vehicle, wherein the method (100) comprises: - Determining (101) a static pressure in at least one hydraulic actuator (205) of a height adjustment system (201) for changing the height of the vehicle, - Assigning (103) a state of the vehicle to the determined static pressure, using a given assignment scheme, - Output (105) of the state of the vehicle, wherein the static pressure in the at least one hydraulic actuator (205) is determined on the basis of a rotational speed and an electrical operating parameter of a pump motor of a pump (213) at at least two predetermined operating points of the pump when pumping hydraulic fluid into the at least one hydraulic actuator.

Inventors

  • Dennis Vogt
  • Malte Pfennig
  • Jan Grymlas

Assignees

  • VIBRACOUSTIC SE

Dates

Publication Date
20260513
Application Date
20250121

Claims (15)

  1. Method (100) for determining a state of a vehicle, wherein the method (100) comprises: - determining (101) a static pressure in at least one hydraulic actuator (205) of a height adjustment system (201) for changing the height of the vehicle, - assigning (103) a state of the vehicle to the determined static pressure, according to a predetermined assignment scheme, - outputting (105) the state of the vehicle, wherein the static pressure in the at least a hydraulic actuator (205) is determined based on a rotational speed and an electrical operating parameter of a pump motor of a pump (213) at at least two predetermined operating points of the pump when pumping hydraulic fluid into the at least one hydraulic actuator.
  2. Procedure (100) according to Claim 1 , characterized in that the method (100) further comprises: - outputting a message describing the state of the vehicle on an output unit.
  3. Procedure (100) according to Claim 2 , characterized in that the message includes a warning that reports a critical loading condition of the vehicle in the event that the determined static pressure exceeds a predetermined threshold.
  4. Method (100) according to one of the preceding claims, characterized in that the static pressure in the at least one hydraulic actuator (205) is determined on the basis of a first rotational speed and a first electrical operating parameter of the pump motor at a first predetermined operating point, as well as a second rotational speed and a second electrical operating parameter at a predetermined second operating point, wherein the first operating point and the second operating point are different.
  5. Procedure (100) according to Claim 4 , characterized in that the static pressure in the at least one hydraulic actuator (205) is determined using the following mathematical relationship: p S t a t i c = p p , A − Q A ⋅ p p , B − p p , A Q B − Q A where p static corresponds to the static pressure in the at least one hydraulic actuator (205), p p,A to the pump pressure at the first operating point, p p,B to the pump pressure at the second operating point, Q A to the volume flow at the pump outlet at the first operating point and Q B to the volume flow at the pump outlet at the second operating point.
  6. Procedure (100) according to one of the Claims 1 until 4 , characterized in that the static pressure is determined using a non-linear function, wherein the non-linear function is determined using pressures and/or rotational speeds at various predetermined operating points.
  7. Method (100) according to one of the preceding claims, characterized in that the at least two operating points have different delivery pressures and delivery volume flows.
  8. Method (100) according to one of the preceding claims, characterized in that the at least two operating points are set by one of the following: speed or current consumption of the motor, volume flow or pressure of the pump (213), electrical or hydraulic power.
  9. Method (100) according to one of the preceding claims, characterized in that the electrical operating parameter of the pump motor comprises a current consumption of the pump motor and/or a power consumption of the pump motor at a known supply voltage and/or a determined phase angle.
  10. Method (100) according to one of the preceding claims, characterized in that when determining the static pressure in the at least one hydraulic actuator (205) a volumetric efficiency is taken into account, wherein the volumetric efficiency is determined by means of a characteristic map, a linear formula or a non-linear formula or is assumed to be constant, and/or the volumetric efficiency is formulated as a function of a temperature of the at least one hydraulic actuator (205), an ambient temperature and/or a number of operating hours of the at least one hydraulic actuator (205).
  11. Method (100) according to one of the preceding claims, characterized in that the rotational speed of the pump motor is measured by means of a sensor or derived from a rotating field of the pump motor or determined on the basis of a course of an electric current drawn by the pump motor.
  12. Method (100) according to one of the preceding claims, characterized in that the pump has a variable displacement volume and the presented method is carried out on the basis of a respective set displacement volume.
  13. Method (100) according to one of the preceding claims, characterized in that when determining the static pressure in the at least one hydraulic actuator (205), a geodetic pressure difference is taken into account with knowledge of a density of the fluid ρ and a height difference z between pump outlet and actuator according to the following mathematical relationship: p A c t o r = p s t a t i c + ρ ⋅ g ⋅ z
  14. System (200) for determining a state of a vehicle, the system comprising: - a height adjustment system (201) for changing the height of the vehicle, - a computing unit (203), wherein the computing unit (203) is configured to execute a method (100) according to one of the Claims 1 until 13 to execute.
  15. Program product, wherein the program product comprises program code means which, when the program product is executed on a computing unit, configure the computing unit to execute a procedure (100) according to one of the Claims 1 until 13 to execute.

Description

The invention relates to a method for determining the state of a vehicle according to claim 1, a system for determining the state of a vehicle according to claim 14 and a program product according to claim 15. Features according to the invention are specified in claim 1. Embodiments are the subject of claims 2 to 13. Determining a vehicle's load status typically requires several sensors, such as pressure gauges. These sensors are expensive and prone to failure. The need to determine the pressure of level control actuators is well-known from air suspension systems. Determining the air spring pressure allows conclusions to be drawn about the vehicle's load condition. For cost reasons, these systems typically use only a single, central pressure sensor integrated into the valve block. To enable this sensor to detect the static pressure of the individual air springs, the valves for one or more air springs are opened. Simultaneously, pressure must be prevented from escaping the valve block, for which the outlet line is closed by an electrically controlled release valve. The disadvantages of this solution are the requirement for a pressure sensor, an electrically controlled release valve, and the corresponding interfaces to the control unit. Another option is direct pressure measurement in the actuators. The disadvantage here is the need for a pressure sensor per actuator, along with the associated wiring and signal interfaces to the control unit. The DE 10 2022 213630 A1 describes a method in which pressure peaks in a pressure system are avoided by means of a specifically calculated speed adjustment of a pump. The DE 10 2022 208706 A1 describes a method in which a gas pressure, a current and a temperature in an actuator are used to calculate a level position. The DE 19 511 591 A1 describes a system for load detection for a vehicle. Furthermore, the DE 199 63 402 A1 , the DE 20 2024 103 450 U1 and the KR 10 2024 0 005 316 A State of the art. Against this background, it is an object of the presented invention to provide a means of determining a state of a vehicle, in particular its loading state, which is robust and cost-efficient. Thus, according to a first aspect of the presented invention, a method for determining the state of a vehicle is presented. The presented method comprises determining a static pressure in at least one hydraulic actuator of a height adjustment system for changing the height of the vehicle, assigning a state of the vehicle to the determined static pressure using a predefined assignment scheme, and outputting the state of the vehicle, wherein the static pressure in the at least one hydraulic actuator is determined using a rotational speed and an electrical operating parameter of a pump motor of a pump at at least two predefined operating points of the pump when pumping hydraulic fluid into the at least one hydraulic actuator. In the context of the presented invention, the output of a state is understood to be a process in which a message describing the state is output, i.e., transferred, for example, to a memory, in particular an error memory, and/or transmitted to a processing function, and/or displayed on an output unit, e.g., a screen. To avoid the use of additional sensors, the presented method is based on an approach in which the static pressure in at least one hydraulic actuator is determined from existing or easily ascertainable measured variables for controlling a motor-pump unit of the height adjustment system. Using the presented method, it is possible to reliably determine the static pressure in the at least one hydraulic actuator of the height adjustment system, although the line losses usually cause a significant difference between the pump output and the actuator and depend on several influencing factors that are not measured. This involves changing the fluid volume in at least one hydraulic actuator of the height adjustment system. This changes the length of the hydraulic actuator. Because the hydraulic actuator is positioned between the chassis and the vehicle body, this change in length causes the body to move vertically. A pump driven by an electric motor with a known gear ratio generates a fluid flow through the lines of the height adjustment system. Electromechanical valves allow the flow to individual hydraulic actuators to be shut off. For example, another valve can be used to regulate the flow from specific hydraulic actuators to a reservoir without causing the pump to run in reverse. The pump's motor is controlled by a control unit. This control unit can, among other things, directly or indirectly monitor the current draw and the motor's speed. Furthermore, it allows for the regulation of the motor current. Control parameters for this regulation can include, among others, the motor current (current control) or the motor speed (speed control). The following relationships apply: The generated torque of an electric motor M <sub>M</sub> corresponds to its current consump