Method for adjusting damping force and damping system for motor vehicle

Abstract

The invention relates to a method for adjusting a damping force of a damping system (10) for a motor vehicle, the damping system (10) having a working cylinder (14) which is at least partially filled with a hydraulic fluid and a pressure adjusting assembly (24) which has a pump (28), a hydraulic accumulator (26), a first valve (44) and a second valve (46) which are each connected to a first and a second working chamber (20, 22) via a hydraulic line (32-39), the valve position of the valve (44, 46) is adjustable, in particular steplessly adjustable, and the valve position of the valve (44, 46) and / or the volume flow and / or the rotational speed of the pump (28) are / is opened / closed as a function of a predeterminable force target value (Fsoll) acting on the piston rod (18). The invention also relates to a damping system (10) for a motor vehicle, comprising a working cylinder (14) which is at least partially filled with a hydraulic fluid, and a pressure regulating assembly (24), which has a pump (28), a hydraulic accumulator (26), a first valve (44) and a second valve (46), which are each connected to a first and a second working chamber (20, 22) via a hydraulic line (32-29), the invention relates to a damping system (10) comprising a pump (28), a piston rod (18), and a valve (44, 46), which is designed such that the valve position is adjustable, in particular steplessly adjustable, and comprising an open-loop / closed-loop control device (52), which is connected to the pump (28) and to the valve (44, 46) and is designed such that it opens / closes the valve position of the valve (44, 46) and / or the volume flow and / or rotational speed of the pump (28) depending on a predeterminable force target value (Fsoll) acting on the piston rod (18).

Description

Field of the Invention

[0001] The present invention relates to a method for adjusting the damping force of a damping system for a motor vehicle and a damping system for a motor vehicle. Background Art

[0002] An active damping system is known from DE102019115492B4. An active damping system is, for example, a damping system having a pump by means of which the pressure in the cylinder chamber can be actively influenced. The active damping systems known from the prior art usually have a large number of hydraulic components and sensors in order to be able to achieve a targeted adjustment of the pressure and the desired damping effect. This is usually accompanied by high manufacturing and maintenance costs. Summary of the Invention

[0003] Starting from this, the object of the present invention is to provide a damping system that enables active damping and can be manufactured at low cost and simply.

[0004] According to the present invention, this object is achieved by a method having the features of independent method claim 1 and a device having the features of independent device claim 8. Advantageous further developments are obtained from the dependent claims.

[0005] According to a first aspect, the present invention includes a method for adjusting the damping force of a damping system for a motor vehicle, wherein the damping system has: a working cylinder at least partially filled with a hydraulic fluid; and a working piston arranged in the working cylinder and axially movable, the working piston having a piston rod, the working piston dividing the working cylinder into a first working chamber and a second working chamber; and a pressure adjustment assembly for adjusting the pressure in the first and second working chambers, wherein the pressure adjustment assembly includes a pump, a hydraulic accumulator, a first valve, and a second valve, which are respectively connected to the first and second working chambers via hydraulic lines, and the valve positions of the valves are adjustable, in particular continuously adjustable. The method includes: open-loop / closed-loop controlling the valve position of the valve and / or the volumetric flow and / or the rotational speed of the pump according to a predetermined force target value F soll acting on the piston rod.

[0006] The damping system preferably includes a shock absorber having a working cylinder and a working piston. The shock absorber is, for example, a monotube shock absorber or a multi-tube shock absorber. A shock absorber for a vehicle, in particular a multi-tube shock absorber, for example includes an outer tube and an inner tube coaxially arranged with the outer tube, in particular the working cylinder, wherein a balance chamber for accommodating the hydraulic fluid is formed between the outer tube and the inner tube, and includes a working piston connected to the piston rod, the working piston being arranged to reciprocate within the inner tube, wherein the inner space of the inner tube is divided into a first working chamber and a second working chamber by the working piston.

[0007] The shock absorber is, for example, a multi-tube shock absorber, in which the balance chamber is partially filled with gas, especially at the upper end. In the balance chamber, an intermediate tube is preferably coaxially mounted with the inner tube and the outer tube, and the intermediate tube is especially mounted on the inner tube. The balance chamber is especially configured as an annular chamber and is delimited by the outer tube and the intermediate tube or the inner tube. The outer tube preferably at least partially forms the housing of the shock absorber. The inner surface of the inner tube is preferably configured as a guide for the working piston. The working piston preferably has a valve device through which the first and second working chambers are connected to each other. Optionally, the multi-tube shock absorber device is configured without an intermediate tube and has an outer gas chamber.

[0008] The shock absorber especially has a closure assembly which is configured and arranged to fluid-tightly seal the inner space of the outer tube on the piston rod side. The end of the inner tube on the piston rod side is preferably fastened to the closure assembly. Opposite the closure assembly, at the end remote from the piston rod, the inner space of the outer tube is preferably fluid-tightly sealed by means of a bottom part. Optionally, a bottom valve is arranged on the bottom part, and the bottom valve is especially mounted on the end of the inner tube remote from the piston rod. The second working chamber is preferably fluid-connected to the balance chamber via the bottom valve. The bottom valve is preferably a check valve which can be flowed through in two directions or only in one direction. For example, the bottom valve is configured as a check valve when the piston moves out of the inner tube in the extension direction, and is configured as a valve generating characteristics when the piston moves into the inner tube in the compression direction.

[0009] The pressure setting assembly is preferably configured such that it sets the pressure in each working chamber, especially the force acting on the working piston. In particular, the pressure setting assembly is configured to set the damping force of the damping system.

[0010] The pump is preferably a two-way hydraulic pump which has at least two connectors for connection to corresponding hydraulic pipelines, wherein each connector can operate as an inlet or an outlet of the hydraulic pump respectively. Preferably, the rotation direction of the pump is reversible such that it can operate in the suction or extrusion mode in two directions respectively. The hydraulic accumulator is, for example, an accumulator filled with hydraulic fluid and gas, and the accumulator is especially pressurized. The pump is preferably connected to a motor for driving the pump, especially an electric motor.

[0011] The valve is preferably a valve which can be adjusted steplessly, especially an electromagnetic valve. Preferably, the hydraulic resistance of the valve is adjustable. The valve position should especially be understood as the position of the adjusting slide of the valve, which releases or closes the flow channel such that the hydraulic resistance changes with different valve positions. Preferably, each valve respectively has a magnetic coil which can be energized and affects the position of the adjusting slide and thus the valve position.

[0012] Force target value F sollis a force value that can be preset manually or automatically, and this force value represents the target force acting on the piston rod, especially the damping force. For example, the force target value F soll is calculated from preset data, such as the pressure in each working chamber. For example, the force target value is calculated based on vehicle data determined via sensors and / or preset. Vehicle data is, for example, the acceleration or speed of the vehicle.

[0013] Based on the preset force target value F soll Adjusting the valve position of the valve and / or the volume flow and / or rotational speed of the pump has the following advantages, namely, the valve and the pump can be adjusted simply, especially based on a model, where it is possible to dispense with measuring the pressure via a pressure sensor, especially the pressure sensors in the inlet line and outlet line of the pump.

[0014] The pressure adjustment assembly preferably includes a plurality of hydraulic lines for connecting the pump and the hydraulic accumulator to the valve and the first and second working chambers of the shock absorber. The pressure adjustment assembly preferably includes at least two check valves. For example, the check valves are connected in series with each other and in parallel with the valve, the pump, and / or the hydraulic accumulator.

[0015] The pump is preferably connected to the first working chamber of the shock absorber via a hydraulic line, and especially to the second working chamber of the shock absorber via another hydraulic line. In particular, the valves are connected in series with each other and connected to the pump via a hydraulic line, where the valve is especially connected in parallel with the pump. For example, the valve is configured such that it can only be flowed through in one direction respectively. Preferably, one valve can be flowed through during the compression phase, while the other valve can be flowed through during the extension phase. In this case, the valves are preferably connected in series with a corresponding check valve.

[0016] The hydraulic accumulator is preferably connected to the two check valves via a hydraulic line such that the connection node of the hydraulic line is arranged between the two check valves. The hydraulic accumulator is preferably additionally connected to the two valves via a hydraulic line such that the connection node of the hydraulic line is arranged between the two valves.

[0017] The pressure adjustment assembly is preferably configured to affect the damping characteristics of the shock absorber and is connected to the shock absorber. The pressure adjustment assembly is preferably configured such that it can achieve active or passive damping of the shock absorber. In the case of passive damping, preferably no additional pressure is fed into the shock absorber via the pump and / or the hydraulic accumulator, where in the case of active damping, the pressure in at least one working chamber is increased via the pump and / or the hydraulic accumulator.

[0018] The force target value F soll is the target value of the force acting on the piston rod, especially the target value of the force acting on the piston rod by means of hydraulic pressure. Therefore, the force target value is the force value that should act on the piston rod, especially the desired force value.

[0019] According to the first embodiment, the force F actually acting on the piston rod is determined. ist Subsequently, preferably, the force target value F soll and the actual force F ist are determined, and the force deviation ΔF therebetween is determined, and the valve position of the control valve, in particular the open-loop / closed-loop control valve, and / or the volume flow and / or rotational speed of the pump are adjusted according to the determined force deviation ΔF. Preferably, the force Fist actually acting on the piston rod is determined based on a model, preferably by means of a pre-determined model. For this purpose, preferably, the required pressure in the corresponding working chamber is determined from the force deviation ΔF, and the valve position of the valve and / or the rotational speed or volume flow of the pump are adjusted such that the corresponding required pressure is achieved. For example, the volume flow or rotational speed of the pump and / or the current or voltage on the pump and / or valve are increased or decreased according to the force deviation ΔF. Preferably, if the force target value F soll is greater than the actual force value F ist , the volume flow or rotational speed of the pump is increased.

[0020] According to another embodiment, the valve position and / or the voltage and / or current intensity present on the valve are predetermined or determined, for example, by means of a sensor SV, and the force F actually acting on the piston rod is determined therefrom. ist For example, the valve position and / or the voltage and / or current intensity present on the valve are predetermined manually or automatically via an open-loop controller / closed-loop controller. The determination of the force F ist is preferably implemented based on a model. Preferably, the force F ist is not calculated by means of the pressure value obtained from the pressure sensor. The sensor SV is preferably configured such that it measures the valve position or determines the valve position from measured values, such as current intensity or voltage. The sensor SV is preferably configured such that it determines the current intensity and / or voltage on the valve and optionally calculates the valve position therefrom. In the sense of the present application, the sensor can also be understood as a device for indirectly determining voltage, current intensity, and / or valve position.

[0021] According to another embodiment, the voltage, current intensity, volume flow, and / or rotational speed present on the pump are determined by means of a sensor SP, and the force F actually acting on the piston rod is determined therefrom. ist The determination of the force F ist is preferably implemented based on a model. In the sense of the present application, the sensor can also be understood as a device for indirectly determining the voltage, current intensity, volume flow, and / or rotational speed of the pump.

[0022] According to another embodiment, the force F actually acting on the piston rod istis determined based on the model by means of a pre-determined pump model, which includes the pump pressure over the operating range of the pump. For this purpose, in particular, a mathematical pump model is pre-determined and stored in the damping device, preferably in the open-loop / closed-loop control device. The pump model preferably correlates the values determined by means of the sensors SV or SP with the determined pump pressure and / or the force F acting on the piston rod ist is associated. The mathematical pump model is preferably a mathematical model obtained through a series of tests performed on a test bench and subsequent verification, which is used to reflect the performance and operating range of the pump. For this purpose, for example, over the operating range of the pump, the pump pressure, volume flow, rotational speed, voltage, current consumption and / or the force present on the piston rod of the pump are measured via corresponding sensors, and a mathematical model is created therefrom, which correlates the values that can be determined via the sensors SV and SP with the corresponding pump pressure or force value F ist is associated. The pump model is preferably a dynamic pump model that can be adapted during the operation of the damping system.

[0023] By establishing the pump model, the pressure sensor used to determine the pump pressure by means of the pressure sensor can be dispensed with, whereby the manufacturing cost of the damping system can be made generally lower and less maintenance is required.

[0024] According to another embodiment, the pump model is continuously monitored and corrected. Preferably, a correction factor is determined during the operation of the damping system. In particular, the correction factor is applied to the pump model during the operation of the damping system in order to adapt the pump model to, for example, different environmental conditions and, in particular, to compensate for the deviation between the model and the actual situation. Preferably, the correction factor is taken into account when determining the actual force value F by means of the pump model ist is considered.

[0025] According to another embodiment, the acceleration and / or level of the shock absorber and / or the absolute acceleration of the vehicle and / or the wheel acceleration or the data of the IMU (inertial measurement unit) are determined by means of the sensor SF, and the correction factor μ for correcting the pump model is calculated from the values determined by means of the sensor SF. The sensor SF is installed, for example, on the vehicle body and / or the wheels of the motor vehicle, in particular on the axle. Preferably, the acceleration and / or level and / or the value of the absolute acceleration of the vehicle of the shock absorber are determined from the determined actual force value F ist is determined. In particular, the calculated acceleration and / or level and / or the absolute acceleration of the vehicle are then compared with the data measured by means of the sensor SF, and for example, the corresponding deviation is calculated. Preferably, the correction factor μ for correcting the pump model is determined from the corresponding deviation. The correction factor is transmitted to the pump model, wherein the pump model is preferably corrected by means of the correction factor. Subsequently, in particular, the actual force value F ist is calculated, which takes into account the determined correction factor of the pump model.

[0026] The invention further includes a damping system for a motor vehicle, having: a working cylinder at least partially filled with a hydraulic fluid; a working piston arranged in the working cylinder and axially movable, the working piston having a piston rod, wherein the working piston divides the working cylinder into a first working chamber and a second working chamber; and a pressure adjustment assembly for adjusting the pressure in the first working chamber and the second working chamber, wherein the pressure adjustment assembly includes a pump, a hydraulic accumulator, a first valve and a second valve, which are respectively connected to the first working chamber and the second working chamber via hydraulic pipelines, and the valves are configured such that the valve positions are adjustable, in particular continuously adjustable. The damping system has an open-loop / closed-loop control device, which is connected to the pump and the valves and is configured such that it adjusts, in particular, the valve positions of the open-loop / closed-loop control valves and / or the volume flow and / or the rotational speed of the pump according to a predefined force target value F acting on the piston rod soll to adjust, in particular, the valve positions of the open-loop / closed-loop control valves and / or the volume flow and / or the rotational speed of the pump.

[0027] The embodiments, features and advantages described above with reference to the method apply equally to the damping system in a corresponding manner for the device.

[0028] The open-loop / closed-loop control device is preferably connected to the pump, in particular a motor, and the first and second valves for open-loop / closed-loop control and for data transmission. In particular, the open-loop / closed-loop control device is connected to sensors SF, SV and SP for data transmission.

[0029] According to one embodiment, the open-loop / closed-loop control device is configured to determine the force F actually acting on the piston rod ist , wherein the open-loop / closed-loop control device is configured to determine the force target value F soll and the force F ist between the force deviation ΔF, and to adjust the valve positions of the open-loop / closed-loop control valves and / or the volume flow and / or the rotational speed of the pump according to the determined force deviation ΔF.

[0030] According to another embodiment, the pressure adjustment assembly has at least one sensor SV for determining the valve position and / or the voltage and / or the current intensity present on the valve or a controller for presetting the valve position and / or the voltage and / or the current intensity present on the valve, wherein the sensor SV or the controller is connected to the open-loop / closed-loop control device, and the open-loop / closed-loop control device is configured to determine the force F actually acting on the piston rod from the data determined by means of the sensor SV or preset by means of the controller ist .

[0031] According to another embodiment, the pressure adjustment assembly has a sensor SP for determining the voltage present on the pump, the current intensity, the volumetric flow of the pump, and / or the rotational speed, and the sensor SP is connected to the open-loop / closed-loop control device, and the open-loop / closed-loop control device is configured to determine the force F actually acting on the piston rod from the data determined by means of the sensor SP ist .

[0032] According to another embodiment, the open-loop / closed-loop control device has a pump model that includes the pump pressure over the operating range of the pump, and the open-loop / closed-loop control device is configured to determine the force F actually acting on the piston rod from the pump model ist . Preferably, the predefined pump model is stored in the open-loop / closed-loop control device.

[0033] According to another embodiment, the pressure adjustment assembly has a sensor SF for determining the acceleration and / or level of the shock absorber, the sensor is connected to the open-loop / closed-loop control device, and the open-loop / closed-loop control device is configured such that it calculates a correction factor for correcting the pump model from the values determined by means of the sensor SF

[0034] The invention also includes a motor vehicle having a chassis and a damping system as described above mounted on the chassis. Preferably, the sensor SF and / or the IMU data sensor for determining the acceleration and / or level of the shock absorber and / or the wheel acceleration, such as a navigation data sensor, is mounted on the chassis of the motor vehicle

[0035] The invention also includes a computer program product for controlling the method for adjusting the damping force of the damping system for a motor vehicle as described above Description of the Drawings

[0036] The invention will be explained in more detail below by means of some embodiments with reference to the drawings

[0037] Figure 1 Schematic diagram showing a damping system according to an embodiment

[0038] Figure 2 Schematic diagram showing an open-loop / closed-loop control device according to an embodiment

[0039] Figure 3 Schematic diagram showing an open-loop / closed-loop control device according to another embodiment Detailed Description

[0040] Figure 1There is shown a damping system 10 for a motor vehicle. In particular, such a damping system is mounted on the chassis of a motor vehicle, not shown here. The damping system 10 includes, for example, a shock absorber 12 having a working cylinder 12, in particular a monotube shock absorber. A working piston 16 is arranged in the working cylinder 12, which is preferably mounted so as to be movable in the axial direction of the working cylinder 14. A piston rod 18 is mounted on the working piston 16, which extends axially centrally through the working cylinder 14 and projects from the working cylinder. The working piston 16 is preferably guided in the working cylinder 14 in a hydraulically sealed manner and divides the working cylinder 14 into a first working chamber 20 on the piston rod side and a second working chamber 22 remote from the piston rod. The working piston 16 preferably includes a valve assembly, in particular for limiting the maximum pressure difference between the two working chambers 20, 22. The shock absorber can also be a multi-tube shock absorber.

[0041] The damping system 10 further includes a pressure setting assembly 24 for setting the damping force acting on the piston rod, in particular for setting the pressure in the first working chamber 20 and the second working chamber 22. The pressure setting assembly 24 includes, for example, a hydraulic accumulator 26 and a pump 28. The pump 28 is preferably connected to a motor 30, in particular an electric motor. The pump 28 is preferably a bi-directional hydraulic pump, which has at least two connections for connection to respective hydraulic lines, wherein each connection can operate as an inlet or an outlet of the hydraulic pump respectively. The pressure setting assembly 24 includes a plurality of hydraulic lines 32 to 38 for connecting the pump 28 and the hydraulic accumulator 26 to the first working chamber 22 and the second working chamber 24 of the shock absorber 20. The pressure setting assembly 24 preferably includes at least two check valves 40, 42. In addition, the pressure setting assembly 24 in particular includes at least two valves, a first valve 44 and a second valve 46, wherein the hydraulic resistance of the valves 44, 46 is adjustable, in particular infinitely adjustable. Optionally, the valves 44, 46 are each configured to be flowed through in only one direction. For example, the valves 44, 46 are solenoid valves that can be flowed through in one direction. In particular, the first valve 44 can only be flowed through in the extension phase, while the second valve 46 can only be flowed through in the compression phase.

[0042] For example, the pump 28 is connected to the first working chamber 20 of the shock absorber 12 via a first hydraulic line 32 and in particular to the second working chamber 22 of the shock absorber 12 via a second hydraulic line 34. The valves 44, 46 are connected in series with each other and are connected to the first and second hydraulic lines 32, 34 via a third hydraulic line 36, wherein the valves 44, 46 are connected in parallel with the pump 28. The check valves 40, 42 are connected in series with each other and are connected to the first and second hydraulic lines 32, 34 via a fourth hydraulic line 38, wherein the check valves 40, 42 are connected in parallel with the valves 44, 46 and the pump 28.

[0043] The hydraulic accumulator 26 is connected to the third and fourth hydraulic lines 36, 38 via a fifth hydraulic line 39. Herein, a first hydraulic connection node 48 for connecting the fifth hydraulic line 39 to the fourth hydraulic line 38 is arranged between two check valves 40, 42. A second connection node 50 for connecting the fifth hydraulic line 39 to the third hydraulic line 36 is arranged, for example, between two valves 44, 46, such that the hydraulic accumulator 26 is connected to the valves 44, 46 especially via the first and second connection nodes 48, 50. The valves 44, 46 are, for example, valves that can be adjusted steplessly, such as solenoid valves.

[0044] The pressure adjustment assembly 24 is preferably connected to the shock absorber 12 in order to influence the damping characteristics of the shock absorber 12. The pressure adjustment assembly 24 is preferably configured such that it can achieve active, semi-active or passive damping of the shock absorber 12. In the case of passive damping, preferably no additional pressure is fed into the shock absorber 12 via the pump 28 and / or the hydraulic accumulator 26. In addition, the valves 44, 46 preferably have a constant, unchangeable valve position in the case of passive damping. In the case of semi-active damping, preferably no additional pressure is fed into the shock absorber 12 via the pump 28 and / or the hydraulic accumulator 26, wherein the valve positions of the valves 44, 46 are changeable. In the case of active damping, a pressure increase in at least one of the working chambers 20, 22 is achieved via the pump 28 and / or the hydraulic accumulator 26, wherein the valve positions of the valves 44, 46 are adjustable.

[0045] For example, when the working piston performs a moving-in motion (compression phase) due to the second working chamber 22 being hydraulically connected to the first working chamber 20 via the valves 44, 46 and the check valve 40, Figure 1 the damping system 10 achieves passive or semi-active damping. Preferably, the hydraulic fluid flows from the second working chamber 22 into the second hydraulic line 34 and then via the valves 44, 46 into the third hydraulic line 36. After the valves, the hydraulic fluid flows into the first hydraulic line 32 and into the first working chamber 20. A partial flow branches off via the second connection node 50 between the two valves 44, 46 and this partial flow flows via the fifth hydraulic line 39 and the first connection node 48 and the check valve 40 into the first hydraulic line 32. In the case of passive or semi-active damping, preferably the damping characteristics are adjusted via the adjustment of the flow resistance of the valves 44, 46.

[0046] In the case of passive damping and the outward movement (extension phase) of the working piston, the first working chamber 20 is hydraulically connected to the second working chamber 22 via valves 44, 46 and check valve 42. Preferably, the hydraulic fluid flows from the first working chamber 20 into the first hydraulic line 32 and then via valves 44, 46 into the third hydraulic line 36. After the valves, the hydraulic fluid flows into the second hydraulic line 34 and into the second working chamber 22. A partial flow branches off via the second connection node 50 between the two valves 44, 46, and this partial flow flows via the fifth hydraulic line 39 and the first connection node 48 and check valve 42 into the second hydraulic line 34.

[0047] In the case of active damping, for example, a pressure increase is achieved in one of the working chambers 20, 22, especially when the working piston 16 is not moving within the working cylinder 14. Preferably, in the case of active damping or shock absorber activation, in addition to the pressure increase caused by the movement of the working piston 16 in the working chambers 20, 22, a further pressure increase is achieved by means of the pump 28 and the hydraulic accumulator 26. The pump 28 is preferably configured such that it can operate towards the first hydraulic line 32 or the second hydraulic line 34. When operating towards the first hydraulic line 32, the first hydraulic line is connected to the fluid outlet of the pump 28. In particular, when the rotational direction of the pump is changed, the pump can operate in the other direction, for example towards the second hydraulic line 34, such that the first hydraulic line 32 is connected to the fluid inlet of the pump and the second hydraulic line 34 is connected to the fluid outlet of the pump 28.

[0048] Preferably, when the pump 28 operates towards the first hydraulic line 32, active damping is carried out to increase the pressure in the first working chamber 20. Additionally, the hydraulic accumulator 26 is preferably connected to the pump 28, wherein the hydraulic fluid flows from the hydraulic accumulator 26 into the fourth hydraulic line 38 and via the check valve 42 into the second hydraulic line 34. The hydraulic fluid preferably flows from the second hydraulic line 34 into the fluid inlet of the pump 28 and then into the first hydraulic line 32. The hydraulic fluid introduced into the first hydraulic line 32 via the hydraulic accumulator 26 and also via the pump 28 achieves a pressure increase in the first hydraulic line 32. A partial flow returns from the first hydraulic line 32 via the third hydraulic line 36 and the first valve 44 to the hydraulic accumulator 26, wherein the remaining partial flow is conveyed via the first hydraulic line 32 to the first working chamber 20 and generates a pressure increase.

[0049] Preferably, active damping is performed when the pump 28 runs towards the second hydraulic line 34 to increase the pressure in the second working chamber 22. Additionally, the hydraulic accumulator 26 is preferably connected to the pump 28, wherein hydraulic fluid flows from the hydraulic accumulator 26 into the fourth hydraulic line 38 and via the check valve 40 into the first hydraulic line 32. The hydraulic fluid preferably flows from the first hydraulic line 32 into the fluid inlet of the pump 28 and then into the second hydraulic line 34. The hydraulic fluid introduced into the second hydraulic line 34 via the hydraulic accumulator 26 and also via the pump 28 causes an increase in the pressure in the second hydraulic line 34. A partial flow returns from the second hydraulic line 34 via the third hydraulic line 36 and the second valve 46 to the hydraulic accumulator 26, wherein the remaining partial flow is conveyed via the second hydraulic line 34 to the second working chamber 22 and causes an increase in pressure.

[0050] The damping system 10 preferably includes an open-loop / closed-loop control device 52. The open-loop / closed-loop control device 52 is connected to the pump 28, in particular the motor 30, and the first and second valves 44, 46, for example for open-loop / closed-loop control and for data transmission.

[0051] In particular, the open-loop / closed-loop control device 52 is configured and arranged such that it open-loop / closed-loop controls the valve positions of the valves 44, 46 and / or the volume flow of the pump 28 according to a predeterminable force target value acting on the piston rod 18.

[0052] Figure 2 Shows a schematic diagram of an open-loop / closed-loop control device 52 for adjusting the damping force, in particular Figure 1 the damping characteristic of the damping system. The open-loop / closed-loop control device 52 is exemplary. The open-loop / closed-loop control device 52 includes, for example, a first computing device 54 for calculating the actual value of the force present on the piston rod 18 and / or the working piston 16. Additionally, the open-loop / closed-loop control device 52 preferably includes a second computing device 56 for calculating the required valve positions of the valves 44, 46 and / or the required volume flow of the pump 28 according to a manually or automatically given force target value F soll In particular, the second computing device 56 is configured such that it determines the required current and / or voltage present on the valve and / or the pump and / or the required volume flow or rotational speed of the pump 28 according to a manually or automatically given force target value F soll

[0053] ​Preferably, the damping system 10, in particular the pressure setting component 24, has sensors SV, SP for determining, in particular measuring, the valve position and / or the voltage and / or current intensity present on the valves 44, 46 and / or the pump and / or the volume flow of the pump 28. In particular, the sensor SV is configured to determine / measure the valve position and / or the voltage and / or current intensity present on the valve, wherein the sensor SP is configured to determine the voltage, current intensity, volume flow and / or rotational speed of the pump 28 present on the pump 28. The sensors SV, SP are preferably connected to the open-loop / closed-loop control device 52 for data transmission. It is also conceivable that the valve position and / or the voltage and / or current intensity present on the valve are not measured via the sensor SV, but are predetermined via the controller, for example. The values predetermined by the controller are preferably transmitted to the open-loop / closed-loop control device 52, in particular the first computing device 54.

[0054] The values determined via the sensors SV, SP, such as the rotational speed, volume flow, current and / or voltage of the pump or the valve position, voltage and / or current intensity of the valves 44, 46, are transmitted to the open-loop / closed-loop control device 52, in particular the first computing device 54.

[0055] The first computing device 54 is preferably configured and arranged such that it determines / calculates the pressure generated by the pump 28 and / or the force F actually acting on the piston rod 18 from the values determined by means of the sensors SV and SP or predetermined by the controller. ist In particular, for this purpose, a mathematical pump model is stored in the computing device 54, which correlates the values determined by means of the sensors with the determined pump pressure and / or the force F acting on the piston rod 28. ist The mathematical pump model is preferably a mathematical model obtained by means of a series of tests on a test bench and subsequent verification, which is used to reflect the performance and operating range of the pump 28. For this purpose, for example, the pump pressure and / or the force present on the piston rod 18 are measured over the operating range of the pump via corresponding sensors, and they are correlated with the values that can be determined via the sensors SV and SP via the mathematical model.

[0056] The open-loop / closed-loop control device 52, in particular the second computing device 56, is preferably configured such that a force target value F for the force acting on the piston rod 18 soll can be given to the second computing device 56. Preferably, the second computing device 56 is configured and arranged such that it increases or decreases the volume flow or rotational speed of the pump 28 and / or the current or voltage present on the pump and / or the valves 44, 46 according to the force target value F. soll In particular, the second computing device 56 is configured and arranged such that it compares the force target value F soll with the actual force value F determined by means of the first computing device 54 istare compared and from which, for example, a force deviation ΔF is determined. For example, the second computing device 56 is configured and arranged such that it increases or decreases the volume flow or rotational speed of the pump 28 and / or the current or voltage present on the pump and / or valves 44, 46 based on the determined force deviation ΔF. Preferably, if the force target value F soll is greater than the force actual value F ist , the volume flow or rotational speed of the pump 28 is increased.

[0057] Preferably, the second computing device 56 is configured and arranged such that it adjusts the valve positions of the valves 44, 46 based on the determined force deviation ΔF. For this purpose, preferably, the open-loop / closed-loop control device 52 determines the required pressure in the Figure 1 respective working chambers 20, 22 from the force deviation ΔF, and adjusts the valve positions of the valves 44, 46 and / or the rotational speed or volume flow of the pump 28 via the open-loop / closed-loop control device 52 such that the respective required pressure is achieved.

[0058] The damping system 10, in particular the pressure adjustment assembly 24, preferably does not have a pressure sensor for measuring the pump pressure.

[0059] Figure 3 shows another embodiment of the open-loop / closed-loop control device 52 for adjusting the damping force, in particular the Figure 1 damping characteristic of the damping system. Figure 3 The open-loop / closed-loop control device 52 of Figure 2 largely corresponds to the open-loop / closed-loop control device 52 of Figure 3 , with the difference that the open-loop / closed-loop control device 52 of Figure 3 also has a third computing device 58. The damping device 10, in particular the pressure adjustment assembly 24, preferably includes a sensor SF for determining, for example, the acceleration and / or level of the shock absorber 12. The sensor SF is installed, for example, on the vehicle body of a motor vehicle. The third computing device 58 is preferably connected to the first and / or second computing devices 54, 56 for data transmission. In particular, the second computing device 56 transmits the determined force actual value F ist to the third computing device 58, and the third computing device is preferably configured such that it determines the value of the acceleration and / or level of the shock absorber 12 from the force actual value F ist .

[0060] Preferably, the third computing device 58 is configured such that it compares the determined acceleration and / or the determined level with the acceleration and level measured by means of the sensor SF and, for example, calculates the corresponding deviation. Preferably, a correction factor μ for correcting the pump model is determined from the respective deviation by means of the computing device 58. The correction factor is transmitted to the first computing device 54, in particular to the pump model, where the first computing device 54 is configured to correct, in particular to adapt, the pump model by means of the correction factor. Subsequently, the actual force value F ist is calculated by means of the first computing device 54, taking into account the determined correction factor μ of the pump model.

[0061] The correction factor takes into account the deviation of the pump model from the actual situation, for example due to external influences such as environmental conditions, temperature or wear. Preferably, the pump model is continuously monitored and corrected by means of the open-loop / closed-loop control device 52, in particular the first and third computing devices 54, 58.

[0062] List of reference numerals

[0063] 10 Damping system

[0064] 12 Shock absorber

[0065] 14 Working cylinder

[0066] 16 Working piston

[0067] 18 Piston rod

[0068] 20 First working chamber

[0069] 22 Second working chamber

[0070] 24 Pressure setting assembly

[0071] 26 Hydraulic accumulator

[0072] 28 Pump

[0073] 30 Motor

[0074] 32 First hydraulic line

[0075] 34 Second hydraulic line

[0076] 36 Third hydraulic line

[0077] 38 Fourth hydraulic line

[0078] 39 Fifth hydraulic line

[0079] 40 Check valve

[0080] 42 Check valve

[0081] 44 First valve

[0082] 46 Second valve

[0083] 48 First connection node

[0084] 50 Second connection node

[0085] 52 Open-loop / closed-loop control device

[0086] 54 First computing device

[0087] 56 Second computing device

[0088] 58 Third computing device

[0089] SV sensor (valve)

[0090] SP sensor (pump)

[0091] SF sensor (vehicle)

[0092] μ correction factor

Claims

1. A method for adjusting the damping force of a damping system (10) for a motor vehicle, wherein, The damping system (10) has: a working cylinder (14) at least partially filled with hydraulic fluid, a working piston (16) arranged within the working cylinder (14) and axially movable, the working piston having a piston rod (18), the working piston (16) dividing the working cylinder (14) into a first working chamber (20) and a second working chamber (22), and a pressure setting assembly (24) for setting the pressure in the first working chamber (20) and the second working chamber (22), wherein the pressure setting assembly includes a pump (28), a hydraulic accumulator (26), a first valve (44) and a second valve (46), which are respectively connected to the first working chamber (20) and the second working chamber (22) via hydraulic lines (32 - 39), and wherein the valve positions of the valves (44, 46) are adjustable, in particular continuously adjustable, characterized in that The valve position of the valves (44, 46) and / or the volume flow and / or rotational speed of the pump (28) are open-loop / closed-loop controlled according to a predeterminable force target value (F soll ) acting on the piston rod (18), wherein the force (F ist ) actually acting on the piston rod (18) is determined, and subsequently the force deviation (ΔF) between the force target value (F soll ) and the force (F ist ) is determined, and the valve position of the valves (44, 46) and / or the volume flow and / or rotational speed of the pump (28) are open-loop / closed-loop controlled according to the determined force deviation (ΔF).

2. The method according to claim 1, wherein, The valve position and / or the voltage and / or the current intensity present at the valve (44, 46) are predetermined or determined by means of a sensor (SV), and the force (F) actually acting on the piston rod (18) is determined therefrom. ist ).

3. The method according to claim 1 or 2, wherein The voltage present on the pump (28), the current intensity, the volumetric flow and / or the rotational speed of the pump (28) are determined by means of at least one sensor (SP), and from these the force (F ist ) actually acting on the piston rod (18) is determined.

4. The method according to any one of the preceding claims, wherein, The determination of the force (F ist ) actually acting on the piston rod (18) is carried out on the basis of a model with the aid of a pre-determined pump model which includes the pump pressure over the operating range of the pump (28).

5. The method according to claim 4, wherein the pump model is continuously monitored and corrected.

6. The method according to claim 4 or 5, wherein, The acceleration and / or level of the shock absorber (12) is determined by means of a sensor (SF), and a correction factor (μ) for correcting the pump model is calculated from the values determined by means of the sensor (SF).

7. A damping system (10) for a motor vehicle, having: a working cylinder (14) at least partially filled with hydraulic fluid, a working piston (16) arranged within the working cylinder (14) and axially movable, the working piston having a piston rod (18), the working piston (16) dividing the working cylinder (14) into a first working chamber (20) and a second working chamber (22), and a pressure setting assembly (24) for setting the pressure in the first working chamber (20) and the second working chamber (22), Among them, the pressure setting assembly (24) includes a pump (28), a hydraulic accumulator (26), a first valve (44) and a second valve (46), which are respectively connected to the first working chamber (20) and the second working chamber (22) via hydraulic lines (32 - 29), and wherein the valves (44, 46) are configured such that the valve positions are adjustable, in particular continuously adjustable, characterized in that The damping system (10) has an open-loop / closed-loop control device (52) which is connected to the pump (28) and the valves (44, 46) and which is configured such that the open-loop / closed-loop control device open-loop / closed-loop controls the valve position of the valves (44, 46) and / or the volumetric flow and / or the rotational speed of the pump (28) as a function of a predeterminable force target value (F soll ) acting on the piston rod (18). wherein the open-loop / closed-loop control device (52) is configured to determine the force (F ist ) actually acting on the piston rod (18), and the open-loop / closed-loop control device (52) is configured to determine the force deviation (ΔF) between the force target value (F soll ) and the force (F ist ), and to open-loop / closed-loop control the valve position of the valves (44, 46) and / or the volume flow and / or the rotational speed of the pump (28) as a function of the determined force deviation (ΔF).

8. The damping system (10) according to claim 7, wherein, The pressure setting assembly (24) includes at least one sensor (SV) for determining the valve position and / or the voltage and / or current intensity present on the valve (44, 46) or includes a controller for predetermining the valve position and / or the voltage and / or current intensity present on the valve, and the sensor (SV) or the controller is connected to the open-loop / closed-loop control device (52), and the open-loop / closed-loop control device is configured to determine the force (F ist ) actually acting on the piston rod (18) from the data transmitted by means of the sensor (SV) or the controller.

9. The damping system (10) according to claim 7 or 8, wherein, The pressure setting assembly (24) includes a sensor (SP) for determining the voltage present on the pump (28), the current intensity, the volumetric flow rate and / or the rotational speed of the pump (28), and the sensor (SP) is connected to the open-loop / closed-loop control device (52), and the open-loop / closed-loop control device is configured to determine the actual force (F ist ) acting on the piston rod (18) from the data determined by means of the sensor (SP).

10. The damping system (10) according to any one of claims 7 to 9, wherein, The open-loop / closed-loop control device (52) has a pump model that includes a pump pressure over the operating range of the pump (28), and the open-loop / closed-loop control device (52) is configured to determine from the pump model the force (F ist ) actually acting on the piston rod (18).

11. The damping system (10) according to claim 10, wherein, the pressure setting assembly (24) has a sensor (SF) for determining the acceleration and / or level of the shock absorber, the sensor being connected to the control loop (52), and the control loop (52) is configured such that the control loop calculates a correction factor (μ) for correcting the pump model from the values determined by means of the sensor (SF).

12. A motor vehicle having a chassis and a damping system (10) according to any one of claims 7 to 11 mounted to the chassis.

13. A computer program product for controlling the method according to any one of claims 1 to 6.

Images