Active Damper System for a Vehicle

Abstract

An active damper system is provided for a vehicle, in particular a motor vehicle. It includes a damper unit with a cylinder, a piston which is guided in the cylinder, and a piston rod which is connected to the piston. The piston divides the cylinder into a first chamber and a second chamber, and the damper unit is designed to be arranged between a body and a wheel of the vehicle. The damper system also has a pump for changing the pressure in the two chambers and for moving the piston, a first valve, a second valve, which is connected to the first valve in series, a third valve, and a fourth valve, which is connected to the third valve in series. The first and second valve are connected in parallel to the third and fourth valve. A fluid-conductive first line leads to the first chamber between the first valve and the second valve, and a fluid-conductive second line leads to the second chamber between the third valve and the fourth valve. A low-pressure side of the pump is connected between the first valve and the fourth valve, and a pressure side of the pump is connected between the second valve and the third valve. The first valve, the second valve, the third valve, and the fourth valve can be switched in order to selectively block and release the flow of fluid. A control unit is provided for switching the four valves such that the pump rotates in the same direction when compressing and rebounding during an electromotor operation and a generator operation.

Claims

1. An active damper system for a vehicle, comprising: a damper unit having a cylinder, a piston which is guided in the cylinder, and a piston rod which is connected to the piston, the piston dividing the cylinder into a first chamber and a second chamber, and the damper unit being configured for arranging between a vehicle body and a wheel of the vehicle; a pump for changing pressures in the first and second chambers and for moving the piston; a first valve and a second valve which is connected in series with the first valve; a third valve and a fourth valve which is connected in series with the third valve, wherein the first and second valves are connected in parallel with the third and fourth valves; a fluid-conducting first line leading between the first valve and the second valve to the first chamber; a fluid-conducting second line leading between the third valve and the fourth valve to the second chamber, wherein a low pressure side of the pump is connected between the first valve and the fourth valve, a pressure side of the pump is connected between the second valve and the third valve, the first valve, the second valve, the third valve and the fourth valve are switchable for selectively closing and opening the fluid flow; and a control unit for switching the first, second, third, and fourth valves, with the result that, in electric motor operation and in generator operation, the pump rotates in the same direction, both during compression and during rebound.

2. The active damper system according to claim 1, wherein the first valve, the second valve, the third valve and/or the fourth valve are check valves which can selectively be closed and opened.

3. The active damper system according to claim 1, further comprising: an electric machine which is operable as an electric motor in order to drive the pump, and which is operable as a generator in order to generate electrical energy by way of the pump.

4. The active damper system according to claim 1, wherein in each case, two valves are actuatable in pairs by the control unit, with the result that the first valve and the third valve always have the same switching position, and with the result that the second valve and the fourth valve always have the same switching position.

5. The active damper system according to claim 1, wherein the control unit for switching the four valves comprises a directional valve which is connected via control lines to the four valves and is connected via a pressure line to the pressure side of the pump.

6. The active damper system according to claim 5, further comprising: a fluid-conducting direct connection, which is switchable by the control unit, between the pressure side and the low pressure side of the pump, thus bypassing the four valves.

7. The active damper system according to claim 6, wherein the switchability of the fluid-conducting direct connection is integrated into the directional valve, or wherein a first additional valve is arranged for the switchability of the fluid-conducting direct connection.

8. The active damper system according to claim 1, further comprising: a first pressure accumulator which is connected between the first valve and the fourth valve; and a second pressure accumulator which is connected between the second valve and the third valve.

9. The active damper system according to claim 8, further comprising: a second additional valve for controlling inflow and outflow at the second pressure accumulator; and/or a third additional valve for closing the pressure side of the pump.

10. The active damper system according to claim 1, wherein the pump is a hydraulic pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic circuit diagram of an active damper system according to the invention in accordance with a first exemplary embodiment,

[0024] FIG. 2 is a schematic circuit diagram of an active damper system according to the invention in accordance with a second exemplary embodiment,

[0025] FIG. 3 is a schematic circuit diagram of an active damper system according to the invention in accordance with a third exemplary embodiment,

[0026] FIG. 4 is a schematic circuit diagram of an active damper system according to the invention in accordance with a fourth exemplary embodiment,

[0027] FIG. 5 is a schematic circuit diagram of an active damper system according to the invention in accordance with a fifth exemplary embodiment, and

[0028] FIGS. 6 and 7 show two arrangements according to the prior art.

DETAILED DESCRIPTION OF THE DRAWINGS

[0029] In the following text, five exemplary embodiments of an active damper system 1 for a motor vehicle will be described with respect to FIGS. 1 to 5. Identical or functionally identical components are provided with the same designations in all exemplary embodiments. FIGS. 1 to 5 show the active damper system 1 in a diagrammatically simplified manner.

[0030] According to FIG. 1, the active damper system 1 includes a damper unit 2 having a cylinder 3 and a piston 4 which is guided in the cylinder 3. The piston 4 is connected fixedly to a piston rod 5. The piston 4 divides the cylinder 3 into a first chamber 6 and into a second chamber 7. The piston rod 5 extends through the first chamber 6.

[0031] The damper unit 2 is arranged in the vehicle between the vehicle body and the wheel. The piston rod 5 is fastened on the vehicle body side. The designation 10 denotes the movement direction of the piston rod 5 during rebound. The damping action is preferably achieved by way of the switching which is shown and the operation of a pump 9 and an electric machine 8 as a generator.

[0032] Furthermore, the active damper system 1 includes the pump 9 which can also be operated as a turbine. The pump 9 is operatively connected to the electric machine 8. Both the electric machine 8 and the pump 9 are operated only in one direction. This applies to operation as an electric motor and to operation as a generator during compression and rebound.

[0033] Furthermore, the active damper system 1 includes a first valve 11, a second valve 12, a third valve 13 and a fourth valve 14. In the exemplary embodiment which is shown, the four valves 11, 12, 13, 14 are configured as check valves which can be closed. The first valve 11 and the second valve 12 are connected in series. The third valve 13 and the fourth valve 14 are likewise connected in series. The first and second valve 11, 12 are arranged parallel to the third and fourth valve 13, 14. A first line 15 branches off between the first valve 11 and the second valve 12. The first line 15 leads to the first chamber 6. A second line 16 branches off between the third valve 13 and the fourth valve 14. The second line 16 leads to the second chamber 7.

[0034] A low pressure line 17 between the first valve 11 and the fourth valve 14 leads to the inlet of the pump 9. A pressure line 18 between the second valve 12 and the third valve 13 leads to the pressure side of the pump 9. Independently of the switching state, the check valves close at least as follows: the first valve 11 closes the fluid flow in the direction of the first chamber 6. The second valve 12 closes the fluid flow in the direction of the pressure side of the pump 9. The third valve 13 closes the fluid flow in the direction of the pressure side of the pump 9. The fourth valve 14 closes the fluid flow in the direction of the second chamber 7.

[0035] The valves 11, 12, 13, 14 can be switched by way of a control unit 19, with the result that they also close a fluid flow in the opposite direction.

[0036] In the first exemplary embodiment, the control unit 19 comprises a directional valve 20, configured as a 4/3-way valve. From the directional valve 20, a first control line 21 leads to the first valve 11 and to the third valve 13 and a second control line 22 leads to the second valve 12 and to the fourth valve 14. The valves 11, 12, 13, 14 can therefore be switched in pairs via the control lines 21, 22.

[0037] The 4/3-way valve 20 has four connectors 25, 26, 27, 28. The first connector 25 and the second connector 26 are connected to the pressure side of the pump 9. By way of the three switching positions a, b, c of the directional valve 20, the first connector 25 and the second connector 26 can be closed in various configurations or can be connected to the third connector 27 and the fourth connector 28. The two control lines 21, 22 are connected to the third connector 27 and to the fourth connector 28.

[0038] A first additional check valve 23 is arranged between the second connector 26 and the pressure side of the pump 9. The first additional check valve 23 closes the fluid flow in the direction of the directional valve 20. Furthermore, the second connector 26 is connected via a second additional check valve 24 to the low pressure side of the pump 9. The second additional check valve 24 closes the fluid flow from the low pressure side in the direction of the directional valve 20.

[0039] In the switching position b of the directional valve 20, the two control lines 21, 22 are pressureless, with the result that the valves 11, 12, 13, 14 which are configured as check valves close merely in one direction. In the switching position, the function corresponds to the conventional arrangement according to FIG. 6. That is to say, the pump 9 and the electric machine 8 which acts as a generator can be operated in one rotational direction for recuperation.

[0040] In the switching position a, the electric machine 8 is operated as an electric motor. Here, the first control line 21 is loaded with pressure, as a result of which the first valve 11 and the third valve 13 close a fluid flow in both directions. Here, the fluid is pumped through the second valve 12 by means of the pump 9. Since the first valve 11 is closed, the fluid cannot flow back to the pump 9 and instead flows into the first chamber 6. The return from the second chamber 7 takes place via the fourth valve 14 to the pump inlet (low pressure side). Here, the damper unit 2 retracts actively.

[0041] In the switching position c, the second control line 22 is under pressure. The fluid flows to the cylinder 3 and from the cylinder 3 are reversed with respect to the switching position a, with the result that the damper unit 2 extends actively.

[0042] The two additional check valves 23, 24 ensure that the control lines 21, 22 are switched to pressureless as required with respect to the low pressure side of the pump 9, in order that the valves 11, 12, 13, 14 are opened.

[0043] In the second exemplary embodiment according to FIG. 2, a direct fluid-conducting connection is provided between the pressure side of the pump 9 and the low pressure side of the pump 9, that is to say between the pump outlet and the pump inlet. A first additional valve 29 is arranged in the direct connection. The direct connection can selectively be closed or opened by way of the first additional valve 29. If the fluid flow via the direct connection is opened, the pump 9 can be kept rotating. The fluid flow can flow back at least partially via the first additional valve 29 to the pump inlet. As a result, the oil pressure can be regulated in a sensitive and highly dynamic manner, since the pump 9 does not have to be accelerated from a standstill. In an optimum manner, the first additional valve 29 is configured as a proportional valve.

[0044] In the third exemplary embodiment according to FIG. 3, there is likewise a direct fluid-conducting connection between the pump outlet and the pump inlet. Here, however, the function of the first additional valve 29 is integrated into the directional valve 20. To this end, the directional valve 20 is configured as a 6/3-way valve. In particular, it is a proportional directional valve. For this embodiment of the directional valve 20, a fifth connector 30 and a sixth connector 31 are additionally provided on the directional valve 20. The fifth connector 30 is connected to the pressure side of the pump 9. The sixth connector 31 leads directly to the low pressure side of the pump 9. In the switching positions a and c, a direct connection takes place between the pressure side and the low pressure side of the pump 9. Here, the direct connection can be regulated proportionally, in particular, with the result that the throughflow quantity can be regulated.

[0045] As an alternative to the use of the first additional valve 29 or to the configuration of the directional valve 20 as a 6/3-way valve, it is also possible to configure the 4/3-way valve 20 which is shown in FIG. 1 as a proportional valve. In this configuration as a proportional valve, it is possible to make a direct return flow possible from the pressure side to the low pressure side via the first and second valve 11, 12 or the third and fourth valve 13, 14.

[0046] The fourth exemplary embodiment according to FIG. 4 shows a first pressure accumulator 32 which is connected to the low pressure side of the pump 9. A second pressure accumulator 33 is connected to the pressure side of the pump 9. A second additional valve 35 is arranged at the inlet of the second pressure accumulator 33. In a first switching position of the second additional valve 35, a check valve closes the fluid flow from the second pressure accumulator 33 into the pressure line 18. The second switching position of the second additional valve 35 makes a fluid flow possible between the pressure line 18 and the second pressure accumulator 33. Pump performance can be buffer-stored by means of the two pressure accumulators 32, 33. This serves, in particular, for supplying pressure during load peaks.

[0047] Furthermore, FIGS. 1 to 5 show a further pressure accumulator 34. The further pressure accumulator 34 is situated on the low pressure side of the pump 9. The further pressure accumulator 34 usually serves to compensate for the displaced volume during compression of the piston rod 5.

[0048] By way of the fifth exemplary embodiment, FIG. 5 shows a third additional valve 36, by way of which the pump inlet can be closed. Furthermore, a throttle is situated here in the second switching position of the second additional valve 35. In certain driving situations, in which the damper unit 2 has to constantly generate a holding force, the electric machine 8 can be switched off. At the same time, the pump inlet is closed via the third additional valve 36. Via the throttle in the second additional valve 35, the second pressure accumulator 33 acts as a bearing spring, the throttle having a damping action. The third additional valve 36 can also be used in the other exemplary embodiments.

[0049] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

LIST OF DESIGNATIONS

[0050] 1 Active damper system [0051] 2 Damper unit [0052] 3 Cylinder [0053] 4 Piston [0054] 5 Piston rod [0055] 6 First chamber [0056] 7 Second chamber [0057] 8 Electric machine [0058] 9 Pump [0059] 10 Rebound direction [0060] 11, 12, 13, 14 Valves (check valves) [0061] 15 First line [0062] 16 Second line [0063] 17 Low pressure line [0064] 18 Pressure line [0065] 19 Control unit [0066] 20 Directional valve [0067] 21 First control line [0068] 22 Second control line [0069] 23 First additional check valve [0070] 24 Second additional check valve [0071] 25 First connector [0072] 26 Second connector [0073] 27 Third connector [0074] 28 Fourth connector [0075] 29 First additional valve [0076] 30 Fifth connector [0077] 31 Sixth connector [0078] 32 First pressure accumulator [0079] 33 Second pressure accumulator [0080] 34 Further pressure accumulator [0081] 35 Second additional valve [0082] 36 Third additional valve [0083] a, b, c Switching positions [0084] 100 Damper unit according to the prior art [0085] 101 Check valves according to the prior art [0086] 102 Pump according to the prior art [0087] 103 Generator according to the prior art [0088] 104 Electric machine according to the prior art [0089] 105 Pump according to the prior art