Wheel suspension system for a motor vehicle

Abstract

A wheel suspension system for a motor vehicle which includes a front axle having two front wheels, to each of which a front hydraulic cylinder is assigned, and a rear axle having two rear wheels, to each of which a rear hydraulic cylinder is assigned. The hydraulic cylinders in a hydraulic system are connected crosswise hydraulically. In order to implement active roll stabilization in a wheel suspension system, a hydraulic pump in the hydraulic system is connected hydraulically between the crosswise-connected hydraulic cylinders.

Claims

1. A wheel suspension system for a motor vehicle, said wheel suspension system comprising: a front axle having two front wheels, to each of which a front hydraulic cylinder is assigned, a rear axle having two rear wheels, to each of which a rear hydraulic cylinder is assigned, wherein the front and rear hydraulic cylinders are hydraulically connected crosswise, and a hydraulic system comprising the front and rear hydraulic cylinders and a reversible hydraulic pump that is connected hydraulically between a first hydraulic subsystem and a second hydraulic subsystem in order to implement active roll stabilization, wherein, in one rotational direction of the reversible hydraulic pump, the pump is configured to supply fluid from the first hydraulic subsystem to the second hydraulic subsystem, thereby actively increasing a fluid pressure in the second hydraulic subsystem and actively decreasing a fluid pressure in the first hydraulic subsystem, and, in an opposite rotational direction of the reversible hydraulic pump, the pump is configured to supply fluid from the second hydraulic subsystem to the first hydraulic subsystem, thereby actively increasing a fluid pressure in the first hydraulic subsystem and actively decreasing a fluid pressure in the second hydraulic subsystem, wherein the first hydraulic subsystem comprises a hydraulic connection between the two front hydraulic cylinders, a hydraulic connection between the two rear hydraulic cylinders, and a first hydraulic pressure accumulator, and wherein the second hydraulic subsystem comprises a hydraulic connection between the two front hydraulic cylinders, a hydraulic connection between the two rear hydraulic cylinders, and a second hydraulic pressure accumulator.

2. The wheel suspension system as claimed in claim 1, wherein the hydraulic pump is connected between a hydraulic line of the first hydraulic subsystem and a hydraulic line of the second hydraulic subsystem.

3. A computer program product having a program code for implementing the active roll stabilization as claimed in claim 1.

4. A control unit for controlling a roll stabilization process by means of the computer program product as claimed in claim 3.

5. The control unit as claimed in claim 4, wherein the control unit receives, as inputs, a speed, a steering wheel angle, and/or a transverse acceleration of the motor vehicle, and, based upon the inputs, controls an electric motor connected to the reversible hydraulic pump for driving the reversible hydraulic pump.

6. A motor vehicle having the wheel suspension system as claimed in claim 1.

7. The wheel suspension system as claimed in claim 1, wherein each of the front and rear hydraulic cylinders has a damper valve.

8. The wheel suspension system as claimed in claim 1, wherein the first hydraulic subsystem is fluidly connected to the second hydraulic subsystem by only the reversible hydraulic pump.

9. The wheel suspension system as claimed in claim 1, further comprising an electric motor connected to the reversible hydraulic pump for driving the reversible hydraulic pump.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Further advantages, features and details of the invention will become apparent from the following description, in which various illustrative embodiments are described in detail with reference to the drawing.

(2) The FIG. illustrates a wheel suspension system for a motor vehicle having a hydraulic system, which comprises a hydraulic pump to form an active roll stabilization system.

DETAILED DESCRIPTION OF THE INVENTION

(3) In the attached FIGURE, a motor vehicle 1 having a wheel suspension system 2 is illustrated in simplified form. A front axle having a front right-hand wheel 4 and a front left-hand wheel 5 at its ends is indicated by a line 3. A rear axle having a rear right-hand wheel 7 and a rear left-hand wheel 8 at its ends is indicated by a line 6.

(4) A direction of forward travel with the motor vehicle 1 traveling straight ahead is indicated by an arrow 9. The wheel suspension system 2 is combined with a hydraulic system 10. The hydraulic system 10 comprises four hydraulic cylinders 11 to 14, which are embodied as double-acting cylinders, each having one piston.

(5) Hydraulic cylinder 11 is assigned to the front right-hand wheel 4, and is therefore also referred to as the front right-hand hydraulic cylinder 11. Hydraulic cylinder 12 is assigned to the front left-hand front wheel 5 and is therefore also referred to as the front left-hand hydraulic cylinder 12. Hydraulic cylinder 13 is assigned to the rear right-hand wheel 7 and is therefore also referred to as the rear right-hand hydraulic cylinder 13. Hydraulic cylinder 14 is assigned to the rear left-hand wheel 8 and is therefore also referred to as the rear left-hand hydraulic cylinder 14.

(6) The hydraulic system 10 furthermore comprises at least two hydraulic pressure accumulators 15, 16. Furthermore, each hydraulic cylinder 11 to 14 in the wheel suspension system 2 is assigned a spring 17 to 20. The springs 17 to 20 are embodied as helical springs and, during operation, perform movements substantially parallel to the pistons in the hydraulic cylinders 11 to 14.

(7) Hydraulic cylinder 11 comprises a first cylinder chamber 21 and a second cylinder chamber 22. Hydraulic cylinder 12 comprises a first cylinder chamber 23 and a second cylinder chamber 24. Hydraulic cylinder 13 comprises a first cylinder chamber 25 and a second cylinder chamber 26. Hydraulic cylinder 14 comprises a first cylinder chamber 27 and a second cylinder chamber 28.

(8) A piston rod 31 of hydraulic cylinder 11 extends to the right through the second cylinder chamber 22 in the FIGURE. A piston rod 32 extends to the left through the second cylinder chamber 24 of hydraulic cylinder 12 in the FIGURE. A piston rod 33 extends to the right through the second cylinder chamber 26 of hydraulic cylinder 13 in the FIGURE. A piston rod 34 extends to the left through the second cylinder chamber 28 of hydraulic cylinder 14 in the FIGURE.

(9) A hydraulic line 41 connects the second cylinder chamber 22 of the front right-hand hydraulic cylinder 11 to the first cylinder chamber 23 of the front left-hand hydraulic cylinder 12. A hydraulic line 42 connects the second cylinder chamber 26 of the rear right-hand hydraulic cylinder 13 to the first cylinder chamber 27 of the rear left-hand hydraulic cylinder 14. Hydraulic lines 41 and 42 are also referred to as connections and belong to a first hydraulic subsystem 61.

(10) A hydraulic line 43 connects the first cylinder chamber 21 of the front right-hand hydraulic cylinder 11 to the second cylinder chamber 24 of the front left-hand hydraulic cylinder 12. A hydraulic line 44 connects the first cylinder chamber 25 of the rear right-hand hydraulic cylinder 13 to the second cylinder chamber 28 of the rear left-hand hydraulic cylinder 14. The two hydraulic lines 43 and 44 are also referred to as connections and belong to a second hydraulic subsystem 62.

(11) A hydraulic line 45 connects the hydraulic pressure accumulator 15 in the second hydraulic subsystem 62 to connection 43 and to connection 44. A hydraulic line 46 connects the hydraulic pressure accumulator 16 in the first hydraulic subsystem 61 to connection 41 and to connection 42.

(12) A hydraulic pump 50 is connected hydraulically between hydraulic lines 45 and 46. The hydraulic pump 50 is embodied as a reversing pump and can be driven in opposite directions by an electric motor 49. Arrows 51 and 52 in the FIGURE indicate that the hydraulic pump 50 delivers hydraulic medium from the hydraulic line 46 of the first hydraulic subsystem 61 to the hydraulic line 45 of the second hydraulic subsystem 62 when the motor vehicle 1 drives around a left-hand bend indicated by a curved arrow 60.

(13) An arrow 54 indicates that the pressure in hydraulic line 45 and in the hydraulic pressure accumulator 15 in the second hydraulic subsystem 62 is being increased by the hydraulic pump 50. At the same time, an arrow 53 indicates that the pressure in the hydraulic pressure accumulator 16 and the hydraulic line 46 of the first hydraulic subsystem 61 is reduced when the hydraulic pump 50 is operated in this delivery direction 51, 52.

(14) The hydraulic pump 50 connects the two hydraulic subsystems 61, 62, which are also referred to as hydraulic circuits 61, 62. By means of the hydraulic pump 50, hydraulic fluid can be delivered from the first hydraulic circuit 61 to the second hydraulic circuit 62 and vice versa.

(15) If the hydraulic pump 50, which is also referred to as “pump” for short, delivers hydraulic fluid from the first hydraulic circuit 61 to the second hydraulic circuit 62, the pressure in the second hydraulic circuit 62 is increased and the pressure in the first hydraulic circuit 61 is reduced. In this way, active roll stabilization for a left-hand bend 60 is possible.

(16) For a right-hand bend, delivery must take place from the second hydraulic circuit 62 to the first hydraulic circuit 61. The resulting pressure difference between the hydraulic circuits 61 and 62 enables active roll stabilization.