Wheel suspension system for a motor vehicle

Abstract

Wheel suspension system (2) for a motor vehicle (1) comprising a front axle (3) with two front wheels (4, 5), each of which is assigned a front hydraulic cylinder (11, 12), and a rear axle (6) with two rear wheels (7, 8), each of which is assigned a rear hydraulic cylinder (13, 14), wherein the hydraulic cylinders (11-14) are hydraulically cross-connected with damper valves in a hydraulic system (10), wherein a hydraulic pump (50) is hydraulically connected in the hydraulic system (10) between a first (61) and second (62) hydraulic subsystem to implement active roll stabilization, characterized in that the hydraulic pump (50) is designed as a reversing pump, wherein the hydraulic pump (50) can actively build up a positive or negative pressure differential in the hydraulic system (10) between the cross-connected hydraulic cylinders (11-14).wherein the first hydraulic subsystem (61) comprises a hydraulic connection (41) between the two front hydraulic cylinders (11, 12), a hydraulic connection (42) between the two rear hydraulic cylinders (13, 14) and a first hydraulic pressure accumulator (16), wherein the second hydraulic subsystem (62) comprises a hydraulic connection (43) between the two front hydraulic cylinders (11, 12), a hydraulic connection (44) between the two rear hydraulic cylinders (13, 14) and a second hydraulic pressure accumulator (15).

Description

[0001] The invention relates to a wheel suspension system for a motor vehicle, comprising a front axle with two front wheels, each of which is assigned a front hydraulic cylinder, and a rear axle with two rear wheels, each of which is assigned a rear hydraulic cylinder, wherein the hydraulic cylinders are hydraulically interconnected in a hydraulic system on each axle. The invention further relates to a method for operating such a wheel suspension system.

[0002] German patent application DE 10 2006 028 511 A1 discloses a suspension system comprising: a first shock absorber, a second shock absorber, a first connecting line extending between the first and second shock absorbers; a second connecting line extending between the first and second shock absorbers; and a control unit connected to the first and second shock absorbers. German patent application DE 10 2008 028 676 A1 discloses a roll control system comprising: first and second shock absorbers, each containing a fluid; a pump fluidically connected between the first and second shock absorbers; a motor connected to the pump; and a controller communicating with the motor, the controller being configured to command the motor to drive the pump in response to a roll signal.wherein the pump supplies fluid from one of the first and second dampers to the other of the first and second dampers in a desired direction in response to the drive by the motor. From German patent application DE 102 16 132 A1, an active suspension system of a vehicle, in particular of a passenger car having at least one axle with two wheels, is known, wherein a vehicle wheel is supported on the vehicle body via a hydraulic piston-cylinder unit, which acts as a damper and hydraulic actuator to introduce an additional force between the wheel and the body, wherein the working chambers of the actuator provided on both sides of the piston in the cylinder of the piston-cylinder unit, the cross-sectional areas of which differ from one another, are each assigned a hydraulic supply line.via which either the same hydraulic pressure supplied by a feed pump can be applied to both working chambers, or a lower hydraulic pressure can be applied to the working chamber with the larger cross-sectional area compared to the other working chamber by means of a pressure regulating valve, wherein the feed pump draws the hydraulic medium from the output of the pressure regulating valve at least at certain operating points.

[0003] The object of the invention is to implement roll stabilization in a wheel suspension system for a motor vehicle, comprising a front axle with two front wheels, each of which is assigned a front hydraulic cylinder, and a rear axle with two rear wheels, each of which is assigned a rear hydraulic cylinder, wherein the hydraulic cylinders are hydraulically cross-connected in a hydraulic system per axle.

[0004] The problem with a wheel suspension system for a motor vehicle, comprising a front axle with two front wheels, each with an associated front hydraulic cylinder, and a rear axle with two rear wheels, each with an associated rear hydraulic cylinder, wherein the hydraulic cylinders are hydraulically interconnected in a hydraulic system on each axle, is solved by hydraulically connecting a hydraulic pump between the two hydraulic subsystems in the hydraulic system to implement active roll stabilization. The wheel suspension system preferably includes a spring and a hydraulic cylinder for each wheel. The spring and the hydraulic cylinder advantageously serve to isolate a sprung part of the motor vehicle from the wheels and axles of the motor vehicle in terms of vibration and to dampen the wheel and body when the motor vehicle rolls over unevenness on a road surface.Furthermore, the wheel suspension system can control and regulate unwanted movements of the vehicle, particularly body roll during cornering. The hydraulic cylinders are designed as double-acting hydraulic cylinders with a piston that separates two cylinder chambers within each cylinder. These cylinder chambers are hydraulically interconnected via hydraulic lines and combined with damping valves. These valves, along with the cross-connection of the hydraulic cylinders, serve to stabilize unwanted body roll during operation. The hydraulic pump can actively create a positive or negative pressure differential in the hydraulic system between the cross-connected hydraulic cylinders. This creates a simple and effective hydraulic roll stabilization system.

[0005] A preferred embodiment of the wheel suspension system is characterized in that the hydraulic pump is designed as a reversing pump. The reversing hydraulic pump can pump hydraulic fluid in two opposite directions.

[0006] Another preferred embodiment of the wheel suspension system is characterized in that the hydraulic pump is connected between a first and a second hydraulic subsystem. This allows the hydraulic pump to transfer hydraulic fluid from the first to the second hydraulic subsystem. The pressure in the second hydraulic subsystem then increases, while the pressure in the first hydraulic subsystem decreases. In this way, active roll stabilization can be easily represented in a corresponding curve.

[0007] Another preferred embodiment of the wheel suspension system is characterized in that 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 accumulator. Advantageously, a hydraulic line extends from the first hydraulic accumulator, connecting the two hydraulic cross-connections of the two axles.

[0008] Another preferred embodiment of the wheel suspension system is characterized in that 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. Advantageously, a hydraulic line extends from the second hydraulic pressure accumulator, connecting the two hydraulic cross-connections of the two axles.

[0009] Another preferred embodiment of the wheel suspension system is characterized in that the hydraulic pump is connected between a hydraulic line of the first hydraulic subsystem and a hydraulic line of the second hydraulic subsystem. Advantageously, the two hydraulic lines correspond to the previously described hydraulic lines originating from the hydraulic accumulators. This arrangement of the hydraulic pump allows for a simple and effective active roll stabilization system.

[0010] Another preferred embodiment involves using a hydraulic pump between the hydraulic lines for each axle. This eliminates the connecting lines between the front and rear axles and allows for variable roll moment distribution.

[0011] Another preferred embodiment is the use of additional valves which can directly connect the hydraulic connections on the hydraulic cylinders, so that compression and rebound movements result in lower pressure changes in the hydraulic accumulators.

[0012] In a method for operating a previously described wheel suspension system, the above-mentioned task is solved alternatively or additionally by actively initiating pressure increases and pressure reductions in the cross-connected hydraulic cylinders using the hydraulic pump for active roll stabilization.

[0013] This allows for a simple way to achieve comfortable damping and roll stabilization in the wheel suspension system.

[0014] The invention further relates to a computer program product comprising program code for carrying out a previously described method. The computer program is preferably executed in a control unit for controlling roll stabilization in the motor vehicle.

[0015] The invention further relates to a control unit for controlling roll stabilization with a previously described computer program. Input variables for the control unit include, for example, vehicle speed, steering wheel angle, lateral acceleration, and / or vehicle height. The computer program contains suitable logic and calculation formulas to determine a suitable pressure and / or current from the input variables, which is then generated in the hydraulic system by the hydraulic pump. The hydraulic pump is advantageously controlled via speed control or pressure control.

[0016] The invention further relates to a motor vehicle with a previously described wheel suspension system, in particular with a previously described control unit.

[0017] Further advantages, features and details of the invention will become apparent from the following description, in which various embodiments are described in detail with reference to the drawing.

[0018] The only accompanying figure shows a wheel suspension system for a motor vehicle with a hydraulic system which includes a hydraulic pump to demonstrate active roll stabilization.

[0019] In the enclosed Fig. 1 is, in simplified terms, a motor vehicle 1 with a wheel suspension system 2 represented by a line 3 is a front axle with a right front wheel 4 and a left front wheel 5 indicated at their ends. By a line. 6is a rear axle with a right rear wheel 7 and a left rear wheel 8 indicated at their ends.

[0020] Through an arrow 9 is a forward direction when the motor vehicle is traveling straight ahead 1 indicated. The wheel suspension system 2 is equipped with a hydraulic system 10 combined. The hydraulic system 10 includes four hydraulic cylinders 11 until 14 , which are designed as double-acting cylinders, each with one piston.

[0021] The hydraulic cylinder 11 is the right front wheel 4 assigned and is therefore also known as the front right hydraulic cylinder 11 The hydraulic cylinder is described. 12 is the front left front wheel 5 assigned and is therefore also known as the front left hydraulic cylinder 12 The hydraulic cylinder is described. 13 is the right rear wheel7 assigned and is therefore also known as the rear right hydraulic cylinder 13 The hydraulic cylinder is described. 14 is the left rear wheel 8 assigned and is therefore also known as the rear left hydraulic cylinder 14 designated.

[0022] The hydraulic system 10 furthermore includes at least two hydraulic pressure accumulators 15 , 16 Furthermore, the wheel suspension system 2 each hydraulic cylinder 11 until 14 a feather 17 until 20 assigned. The springs 17 until 20 are designed as coil springs and, during operation, guide movements essentially parallel to the pistons in the hydraulic cylinders. 11 until 14 out of.

[0023] The hydraulic cylinder 11 includes a first cylinder space 21 and a second cylinder chamber 22 The hydraulic cylinder12 includes a first cylindrical space 23 and a second cylinder chamber 24 The hydraulic cylinder 13 includes a first cylindrical space 25 and a second cylinder chamber 26 The hydraulic cylinder 14 includes a first cylindrical space 27 and a second cylinder chamber 28 .

[0024] A piston rod 31 of the hydraulic cylinder 11 extends through the second cylinder chamber 22 in Fig. One to the right. A piston rod 32 extends through the second cylinder chamber 24 of the hydraulic cylinder 12 in Fig. 1 to the left. A piston rod 33 extends through the second cylinder chamber 26 of the hydraulic cylinder 13 in Fig. One to the right. A piston rod 34 extends through the second cylinder chamber 28 of the hydraulic cylinder 14in Fig. 1 to the left.

[0025] A hydraulic line 41 connects the second cylinder chamber 22 of the front right hydraulic cylinder 11 with the first cylinder chamber 23 of the front left hydraulic cylinder 12 A hydraulic line 42 connects the second cylinder chamber 26 of the rear right hydraulic cylinder 13 with the first cylinder chamber 27 of the rear left hydraulic cylinder 14 The hydraulic lines 41 and 42 are also referred to as connections and belong to a first hydraulic subsystem 61 .

[0026] A hydraulic line 43 connects the first cylinder chamber 21 of the front right hydraulic cylinder 11 with the second cylinder chamber 24 of the front left hydraulic cylinder 12 A hydraulic line 44connects the first cylinder chamber 25 of the rear right hydraulic cylinder 13 with the second cylinder chamber 28 of the rear left hydraulic cylinder 14 The two hydraulic lines 43 and 44 are also referred to as connections and belong to a second hydraulic subsystem 62 .

[0027] A hydraulic line 45 connects the hydraulic pressure accumulator 15 in the second hydraulic subsystem 62 with the connection 43 and with the connection 44 A hydraulic line 46 connects the hydraulic pressure accumulator 16 in the first hydraulic subsystem 61 with the connection 41 and with the connection 42 .

[0028] A hydraulic pump 50 It is hydraulically connected between the hydraulic lines 45 and 46 switched. The hydraulic pump50 It is designed as a reversible pump and is powered by an electric motor. 49 Can be driven in opposite directions. By arrows 51 and 52 is in Fig. 1 indicated that the hydraulic pump 50 Hydraulic fluid from the hydraulic line 46 of the first hydraulic subsystem 61 into the hydraulic line 45 of the second hydraulic subsystem 62 promotes when the motor vehicle1 is guided by a curved arrow 60 Drives along a suggested left-hand bend.

[0029] Through an arrow 54 It is indicated that the hydraulic pump 50 the pressure in the hydraulic line 45 and the hydraulic pressure accumulator 15 in the second hydraulic subsystem 62 is increased. At the same time, an arrow indicates 53 indicated that the pressure in the hydraulic pressure accumulator 16 and the hydraulic line 46of the first hydraulic subsystem 61 is reduced when the hydraulic pump 50 in this funding direction 51 , 52 is operated.

[0030] The hydraulic pump 50 connects the two hydraulic subsystems 61 , 62 , which are also known as hydraulic circuits 61 , 62 be referred to as such. With the hydraulic pump 50 Can hydraulic fluid from the first hydraulic circuit 61 into the second hydraulic circuit 62 to be promoted, and vice versa.

[0031] Does the hydraulic pump deliver 50 , which is also referred to as a pump for short, hydraulic fluid from the first hydraulic circuit 61 into the second hydraulic circuit 62 , the pressure in the second hydraulic circuit increases 62 and the pressure in the first hydraulic circuit is reduced 61 This is how active roll stabilization is used for a left turn. 60 possible.

[0032] For a right turn, the second hydraulic circuit is required. 62 in the first hydraulic circuit 61 to be promoted. Due to the resulting pressure difference between the hydraulic circuits. 61 and 62 Active roll stabilization is enabled. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102006028511 A1

[0002] DE 102008028676 A1

[0002] DE 10216132 A1

[0002]

Claims

[1] Wheel suspension system (2) for a motor vehicle (1) comprising a front axle (3) with two front wheels (4,5) to which a front hydraulic cylinder (11,12) is assigned, and a rear axle (6) with two rear wheels (7,8) to which a rear hydraulic cylinder (13,14) is assigned, wherein the hydraulic cylinders (11-14) are hydraulically cross-connected with damper valves in a hydraulic system (10), characterized by , that a hydraulic pump (50) in the hydraulic system (10) is hydraulically connected between a first (61) and second (62) hydraulic subsystem in order to realize active roll stabilization. [2] Wheel suspension system according to claim 1, characterized by that the hydraulic pump (50) is designed as a reversing pump. [3] Wheel suspension system according to claim 2, characterized by, that the first hydraulic subsystem (61) comprises a hydraulic connection (41) between the two front hydraulic cylinders (11,12), a hydraulic connection (42) between the two rear hydraulic cylinders (13,14) and a first hydraulic pressure accumulator (16). [4] Wheel suspension system according to claim 2 or 3, characterized by , that the second hydraulic subsystem (62) comprises a hydraulic connection (43) between the two front hydraulic cylinders (11,12), a hydraulic connection (44) between the two rear hydraulic cylinders (13,14) and a second hydraulic pressure accumulator (15). [5] Wheel suspension system according to any one of claims 2 to 4, characterized by , the hydraulic pump (50) is connected between a hydraulic line (46) of the first hydraulic subsystem (61) and a hydraulic line (45) of the second hydraulic subsystem (62). [6] Method for operating a wheel suspension system according to any one of the preceding claims, characterized by , that with the hydraulic pump (50) active pressure increases and pressure reliefs are initiated in the cross-connected hydraulic cylinders (11-14) for active roll stabilization. [7] Computer program product comprising program code for performing a method according to claim 6. [8] Control unit for controlling a roll stabilization system with a computer program product according to claim 7. [9] Motor vehicle (1) with a wheel suspension system (2) according to any one of claims 1 to 6, in particular with a control unit according to claim 8.

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