WO2004000584A1

WO2004000584A1 - Suspension system for a vehicle

Info

Publication number: WO2004000584A1
Application number: PCT/EP2003/006285
Authority: WO
Inventors: Frank-Detlef Speck
Original assignee: Zf Friedrichshafen Ag
Priority date: 2002-06-20
Filing date: 2003-06-14
Publication date: 2003-12-31
Also published as: DE10227416A1

Abstract

Disclosed is a suspension system for a vehicle, comprising at least one suspension-absorber device (3A, 3B) which is assigned to a wheel (2A, 2B) and a low-end displacing device (4A, 4B) for the suspension-absorber device (3A, 3B). A roll-stabilizing spring element (9) which extends essentially transversal to the direction of the vehicle is disposed between two wheels that are arranged adjacent to each other in the transversal direction of the vehicle. Said spring element (9) is fixed to the body and to one respective end of the low-end displacing device (4A, 4B), which is located across from a wheel (2A, 2B) axle (7A, 7B).

Description

Suspension system for a vehicle

The invention relates to a suspension system for a vehicle, each with at least one mechanical spring damper device assigned to a wheel.

Active suspension systems for vehicles or motor vehicles are known from practice, in which a supporting unit is provided between a vehicle body and vehicle wheels. Support units of this type each comprise an actively stroke-adjustable actuator and a passive spring device arranged in series with it. The abutment of the spring device on the body side can be adjusted vertically relative to the vehicle body by means of the actuating mechanism in order, for example, to be able to carry out roll stabilization or roll compensation.

To increase the rigidity of such suspension systems, so-called stabilizers for additional roll stabilization are installed in practice, which represent a spring element which extend essentially in the transverse direction of the vehicle and are arranged between two wheels arranged adjacent to one another in the transverse direction of the vehicle. Such a stabilizer is mounted on the vehicle body side and in each case on an axle of a wheel, so that a so-called sinking in of the suspension system, as occurs, for example, when cornering at high speed, is avoided and cornering behavior is improved.

Known active suspension systems designed in this way have the disadvantage, however, that the stabilizer counteracts this when the foot point is actively adjusted, since with an adjustment of the base point of a spring damper device in the direction of the vehicle body or with an adjustment of the base point, in which the distance between the axle and the vehicle body is increased, tensile and / or compressive stresses are built up in the stabilizer, but this is energetically unfavorable is and affects the operation of the stabilizer.

In addition, due to the foot point adjustment and the tensions generated in the stabilizer

Adjustment of the spring damper device is impaired, so that the spring damper device is also adversely affected in its mode of operation.

The object of the present invention is to provide a suspension system with a stabilizer, in which a base point adjustment of a spring-damper device can be carried out without affecting the functioning of the stabilizer and the spring-damper device.

According to the invention, this object is achieved with a suspension system according to the features of claim 1.

In a suspension system according to the invention, in which a spring element for roll stabilization, which extends essentially in the transverse direction of the vehicle and is arranged between two wheels arranged adjacent in the transverse direction of the vehicle, is fixed on the body side and in each case on the end of a base point adjusting device facing away from an axis of a wheel advantageously a base of a spring damper device and the provided for additional roll stabilization spring element or stabilizer jointly adjusted. In this way, when the base point of a spring-damper device is adjusted, the build-up of component stresses in the stabilizer, which adversely affect the functioning of the stabilizer, is avoided in a simple manner.

Furthermore, the constructive design of the suspension system according to the invention represents a more energy-efficient arrangement in comparison to constructions known from practice, in which a stabilizer is fixed to an axle of a wheel, since energetic losses when adjusting a base point of a spring-damper device , which arise in the known solutions due to the build-up of stresses in a stabilizer.

Further advantages and advantageous configurations of the subject matter according to the invention can be found in the patent claims, the description and the drawing.

Six advantageous exemplary embodiments of the suspension system according to the invention are shown schematically simplified in the drawing and are explained in more detail in the following description. It shows:

Fig.l is a schematic diagram of a suspension system with a stabilizer arranged between two base adjustment devices; 2 shows a suspension system according to FIG. 1, wherein a

Damping element is integrated in a mechanical spring;

3 shows a suspension system with a controllable connection between two hydraulically controllable base adjustment device, a hydraulic pump being designed as a reversible pump;

4 shows a suspension system according to FIG. 3, wherein a

Damping element is integrated in a mechanical spring;

5 shows a suspension system according to FIG. 1, one

A hydraulic cylinder of a foot point adjustment device is controlled via a 3/3-way valve and

6 shows a further development of the suspension system according to

Fig. 5, wherein a pressure translator is additionally provided for controlling the foot adjustment devices.

1 shows a suspension system 1 for a motor vehicle, which is designed with a mechanical spring damper device 3A, 3B assigned to a wheel 2A, 2B. Furthermore, a foot point adjusting device 4A, 4B is provided for each of the spring damper devices 3A, 3B, which is shown in a highly schematic manner.

The foot point adjustment devices 4A, 4B can be controlled hydraulically in the present case, the control being on different ways can be done. Special descriptions of the hydraulic control of the foot adjustment devices are discussed in the description of FIGS. 3 to 6.

As an alternative to a hydraulic control of the foot point adjustment devices, it can also be provided that the foot point adjustment devices of the suspension system are adjusted electromechanically. The base point of a spring-damper device can preferably be adjusted via a spindle that can be actuated by an electric motor. It is, of course, at the discretion of the person skilled in the art, depending on the respective application, to provide other suitable constructive configurations of an electromechanical control of the foot point adjustment devices.

The two spring damper devices 3A, 3B shown in FIG. 1 are each designed with a damping element 5A, 5B and each with a mechanical spring 6A, 6B, which are connected in parallel to one another. The base adjustment device 4A, 4B and the mechanical springs 6A, 6B are arranged in series with one another, the base adjustment devices 4A, 4B with the end facing away from the mechanical springs 6A, βB each having an axle 7A or 7B of one of the wheels 2A or 2B are connected.

The connection between the base adjustment devices 4A, 4B and the axes 7A, 7B each provide one

Base of the mechanical springs 6A, 6B. The damper elements 5A, 5B are at one end of the vehicle body on a body 8 of a body not shown Motor vehicle and with its other end each fixed to one of the axes 7A, 7B.

A spring element 9 extending in the vehicle transverse direction is arranged between the two foot point adjustment devices 4A, 4B for additional roll stabilization. The spring element or the stabilizer 9 is fixed on the body side and with its free ends at the ends of the foot point adjusting devices 4A, 4B facing away from the axes 7A, 7B.

The stabilizer 9 is shown in a highly schematic manner in FIG. 1 as a component formed from tubular material and has an essentially trapezoidal configuration, the upper, shorter side being fixed to the body 8 at two points. Starting from the two fastening points of the stabilizer 9 on the body 8, the latter is formed with two bending points, to which two branches adjoin which run in the direction of the wheels 2A, 2B. The free end of the branches of the stabilizer 9 is each connected to one of the two base adjustment devices 4A, 4B in the region of the connection point between the mechanical spring 6A or 6B and the base adjustment device 4A or 4B.

The stabilizer 9 is designed as a spring-elastic spring element, which unfolds its full effect only when the two spring damper devices 3A, 3B deflect in opposite directions, ie when a wheel 2A or 2B experiences a displacement with respect to the vehicle body, which corresponds to the movement of the other wheel 2B or 2A with respect to the vehicle body is opposite. If the two wheels 2A, 2B move in the same direction, the influence is of the stabilizer 9 on the suspension system 1 only slightly.

If active roll stabilization is carried out by adjusting the base of the spring damper devices 3A, 3B by means of one of the two base adjustment devices 4A, 4B or at the same time both base adjustment devices 4A, 4B, the stabilizer 9 is not adjusted or is not braced against the body, which is why the fixing of the stabilizer 9 shown in FIG. 1 represents an energetically favorable arrangement.

In deviation from this, the stabilizer can also be designed with a structural design that is adapted to the available installation spaces, the respectively selected design or shape of the stabilizer having the same supporting effect or improving the roll stabilization as the shape of the stabilizer shown in FIG. 1 ,

2 shows a further exemplary embodiment of the suspension system 1, only the spring-damper devices 3A, 3B being designed differently, since the damper elements 5A, 5B are arranged within the mechanical springs or 6A, 6B, which are preferably designed as helical springs. The base points of the mechanical springs 6A, 6B and the damper elements 5A, 5B can thus be adjusted together, which is particularly advantageous in the case of a strut arrangement.

This embodiment variant of the spring-damper devices 3A, 3B contrasts with the spatially offset arrangement of the damper elements 5A, 5B and the mechanical springs 6A, 6B represent an energetically more favorable embodiment, although the coaxial arrangement of the damper elements 5A, 5B and the mechanical springs 6A, 6B requires a slightly higher control effort than the spatially separated arrangement.

3 to 6 show further exemplary embodiments of the suspension system 1, the same reference symbols as in the description of FIGS. 1 and 6 being used in the description of FIGS. 3 to 6 for identical and functionally identical components of the suspension system Fig. 2 can be used. Different configurations of a hydraulic control of the foot point adjustment devices of the suspension system are discussed in more detail below.

3, a suspension system 1 according to FIG. 1 is shown, a controllable connection 10 for shifting pressure medium from the foot point adjustment device 4A to that for performing an active roll compensation between the two hydraulic foot point adjustment devices 4A, 4B Base adjustment device 4B and vice versa is provided.

In the controllable connection 10, a hydraulic pump 11 is integrated, which is designed as a reversible pump. Between the hydraulic pump 11 and a hydraulic cylinder 12A of the foot point adjusting device 4A and between the hydraulic pump 11 and a hydraulic cylinder 12B of the foot point adjusting device 4B, a locking member 13A or 13B is arranged, the locking members each as 2/2-way Valves 13A and 13B are executed. Furthermore, in the area between the hydraulic pump 11 and the 2/2-way valve 13A or the 2/2-way valve 13B, a line 14A or 14B branches off, which opens into a pressure medium reservoir 15. The two lines 14A, 14B are each designed with controllable further 2/2-way valves 16A, 16B, by means of which the two lines 14A, 14B and a connection between the hydraulic pump 11 and the pressure medium reservoir 15 can be blocked.

The hydraulic cylinders 12A, 12B are connected in series with the mechanical springs 6A, 6B, a piston rod 17A, 17B being connected to an axle 7A, 7B of a wheel 2A, 2B and the connections between the piston rods 17A, 17B and the axles 7A , 7B each represent a base point of the mechanical springs 6A and 6B.

The combination of the reversible hydraulic pump 11 driven by an electric motor 18 with several, preferably electromagnetically unlockable blocking members or 2/2-way valves 13A, 13B, 16A, 16B enables the functions of sealing, suspension, roll stabilization, level regulation and kneeling with the suspension system 1 can be carried out in a simple manner.

The electric motor 18 used to drive the hydraulic pump 11 is preferably designed as an asynchronous motor. The asynchronous motor is particularly suitable here because it generates high torque at low speeds and has compact inverters, which is why it requires only a small installation space.

With the preferably electromagnetically unlockable 2/2-way valves 13A, 13B, 16A, 16B are in different Switching positions of the valves also various functions of the suspension system 1 can be carried out. Thus, the valves 13A, 13B assigned to the two hydraulic cylinders 12A, 12B remain closed if a purely passive vehicle without roll compensation is to be represented.

For roll stabilization, the hydraulic pump 11 delivers a certain volume of pressure medium depending on the direction of rotation of the electric motor 18 from the hydraulic cylinder 12A on one side of the vehicle to the hydraulic cylinder 12B on the other side of the vehicle or vice versa.

To implement active roll compensation, the valves 13A, 13B located between the hydraulic cylinders 12A, 12B and the hydraulic pump 11 are opened and the valves 16A, 16B arranged in the lines 14A, 14B are closed. The electric motor 18 drives the hydraulic pump 11 in a clockwise or clockwise direction depending on the desired or required direction of displacement of the pressure medium, the valves 13A, 13B arranged between the hydraulic pump 11 and the hydraulic cylinders 12A, 12B being opened and those in the to the pressure medium reservoir 15 leading lines arranged valves 16A, 16B are closed.

For a one-sided lowering of a vehicle side, the so-called kneeling, the valves 13A, 16A assigned to one vehicle side are closed and the valves 13B, 16B, which are assigned to the other vehicle side, are open. The hydraulic oil or the pressure medium of the loaded hydraulic cylinder 12B is drained into the pressure medium reservoir 15, which leads to the lowering of this vehicle side. To get the vehicle back into a horizontal To bring position, the valves 13A, 16A or 13B, 16B are opened or closed in pairs, while the hydraulic pump 11 conveys the pressure medium into the relevant hydraulic cylinder 12A or 12B of the spring system 1.

For level regulation, for example, the valve 13A is activated in such a way that it is in the flow position. The volume of pressure medium conveyed by the hydraulic pump 11 is conveyed from the pressure medium reservoir 15 into the hydraulic cylinder 12A, as a result of which a body structure 8 connected to the mechanical springs 6A, 6B is raised with respect to a surface of the vehicle. In order to lower the body structure 8 again, all valves 13A, 13B, 16A, 16B are opened so that the pressure medium can be returned to the pressure medium reservoir 15. The hydraulic system of the suspension system 1 can be protected by a pressure relief valve which is integrated into the lines which connect the hydraulic cylinders 12A, 12B to the hydraulic pump 11.

In the area of the base points of the mechanical springs 6A, 6B and the base points of the damper elements 5A, 5B, a positive guide, not shown, is provided. The positive guidance ensures that an adjustment of the base points of the mechanical springs 6A, 6B results in a simultaneous adjustment of the base points of the damper elements 5A, 5B and the axes 7A, 7B are not tilted.

In a further development of the

Suspension system according to the invention, the hydraulic cylinders of the base adjustment devices described above can also be connected to other base points via the controllable connection. Adjustment devices of the motor vehicle can be fluidly connected so that roll stabilization can also be carried out in the longitudinal direction of the vehicle and / or in the diagonal direction.

FIG. 4 shows the suspension system 1 from FIG. 2, the hydraulic system described in FIG. 3 being integrated between the two base adjustment devices 4A, 4B. The damper elements 5A, 5B are designed without positive guidance and are arranged coaxially with the mechanical springs 6A, 6B, whereby on the one hand an adjustment of the piston rods 17A, 17B also acts directly on the damper elements 5A and 5B without positive guidance and on the other hand the spring damper devices 3A, 3B have a smaller overall space requirement.

With reference to FIG. 5, a further embodiment of the suspension system 1 is shown, which in principle corresponds to the suspension system shown in FIG. 1. The two hydraulically controllable foot point adjustment devices 4A, 4B are coupled via a further hydraulic actuator, which is described in more detail below.

The hydraulic actuator system according to FIG. 5 has a hydraulic pump 11 designed as a one-way pump, by means of which pressure medium can be guided from the pressure medium reservoir 15 via a 3/3-way valve 19A, 19B to the hydraulic cylinder 12A or 12B to be controlled in each case. The 3/3-way valves 19A, 19B each represent a combination of the 2/2-way valves 8A, 16A and the 2/2-way valves 8B, 16B, depending on the possible switching positions of the two 3rd / 3-way valves 19A, 19B the above-described functions sealing, suspension, roll stabilization can be carried out in a simple manner with the suspension system 1.

6 shows the suspension system 1 with the embodiment of the spring damper devices shown in FIG. 1, the controllable connection 10 between the two hydraulic cylinders 12A, 12B being implemented with a pressure intensifier 20.

The pressure booster 20 has four chambers 21A, 21B, 22A and 22B, the chambers 21A and 21B each being connected to the hydraulic cylinders 12A and 12B via a line branch of the controllable connection 10. The chambers 22A and 22B can be supplied with pressure medium from the hydraulic pump 11, which is designed as a unidirectional pump, via further lines 23A, 23B when a 3/4-way valve 24 arranged between the pressure booster 20 and the hydraulic pump 11 is in the corresponding switching position. The 3/4-way valve 24 can preferably be held electromagnetically and mechanically with spring elements in one of the three possible switching positions.

The pressure intensifier 20 is designed with a fixed intermediate wall 25 and with two movable intermediate walls 26A and 26B designed as separating pistons. The two movable partitions 26A, 26B are firmly connected to one another by a connecting piston 27. The connecting piston 27 is guided in a longitudinally movable manner in the fixed intermediate wall 25 and penetrates the two chambers 22A, 22B in such a way that an effective area of the chambers 21A, 21B is larger than the effective area of the chambers 22A, 22B. This means that the hydraulic pump is pe 11 into the chambers 22A, 22B a larger amount of pressure medium is supplied to the respective hydraulic cylinder 12A or 12B to be supplied.

In addition, the hydraulic pump 11 can be connected directly to the hydraulic cylinders 12A, 12B via further connecting lines 28A, 28B. For this purpose, a 3/3-way valve 19A and 19B is integrated in the connecting lines 28A, 28B. If the valves 19A, 19B are in the appropriate position, the hydraulic cylinders 12A, 12B are supplied with pressure medium directly by the hydraulic pump 11. In a further switching position of the valves 19A, 19B, pressure medium is discharged from the hydraulic cylinders 12A, 12B into the pressure medium reservoir 15.

Furthermore, there is the possibility of shifting pressure medium from the hydraulic cylinder 12A to the other hydraulic cylinder 12B or in the opposite direction due to a pressure gradient between the two hydraulic cylinders 12A, 12B without compressing the hydraulic pump 11. In addition, there is the possibility of switching the 3/3-way valves 19A, 19B in such a way that, in addition to the fluidic operative connection provided via the pressure intensifier 20, there is a further direct fluidic connection between the two hydraulic cylinders 12A, 12B.

Of course, it is at the discretion of the person skilled in the art to design the spring-damper devices of the suspension system according to FIG. 6 such that the damping element of a spring-damper device is spatially integrated in the mechanical spring in the manner shown in FIG. 2. Deviating from the embodiments of the suspension according to the invention described in relation to FIGS. 1 to 6, it can also be provided that the spring damper devices are each designed as hydropneumatic suspensions and are connected in series with the base point adjusting devices.

reference numeral

1 suspension system 2A, 2B wheel

3A, 3B spring damper device

4A, 4B hydraulic foot point adjustment device

5A, 5B damping element

6A, 6B mechanical spring 7A, 7B axis

8 body

9 stabilizer

10 controllable connection

11 Hydraulic pump 12A, 12B hydraulic cylinder

13A, 13B blocking element, 2/2-way valve

14A, 14B line

15 pressure medium reservoir

16A, 16B second 2/2-way valve 17A, 17B piston rod

18 electric motor

19A, 19B 3/3-way valve

20 pressure translators

21A, 21B chamber of the pressure intensifier 22A, 22B chamber of the pressure intensifier

23A, 23B further lines

24 3/4-way valve

25 partition

26A, 26B partition 27 connecting piston

28A, 28B connecting lines

Claims

Patent claims

1. Suspension system (1) for a vehicle, each with at least one spring damper device (3A, 3B) assigned to a wheel (2A, 2B) and with a foot point adjusting device (4A, 4B) for the spring damper device (3A, 3B) , wherein between two wheels (2A, 2B) arranged adjacent to one another in the vehicle transverse direction there is arranged a spring element (9) for roll stabilization which essentially extends in the transverse direction of the vehicle, the spring element on the body side and in each case on one axle (7A, 7B) of a wheel ( 2A, 2B) facing away from the end of the foot adjustment devices (4A, 4B).

2. Suspension system according to claim 1, characterized in that the foot point adjusting device (4A, 4B) can be controlled hydraulically.

3. Suspension system according to claim 2, characterized in that the base adjustment device (4A, 4B) comprises a hydraulic cylinder (12A, 12B), the piston rod (17A, 17B) with an axis (7A, 7B) of a wheel (2A, 2B ) connected is.

4. Suspension system according to claim 3, characterized in that the spring element (9) is fixed in each case at the end of the hydraulic cylinder (12A, 12B) facing away from the axis (7A, 7B).

5. Suspension system according to claim 3 or 4, characterized in that a conveyor (11) for guiding pressure medium to the hydraulic cylinder the (12A, 12B) of the base adjustment device (4A, 4B) is provided.

6. Suspension system according to claim 4, characterized in that the delivery device for guiding pressure medium is designed as a hydraulic pump (11)

7. Suspension system according to one of claims 2 to 6, characterized in that between at least two base adjustment devices (4A, 4B) two wheels (2A, 2B) a controllable connection (10) for moving pressure medium between the base adjustment devices (4A , 4B) is provided.

8. Suspension system according to claim 7, characterized in that the conveying device for guiding pressure medium is designed as a reversible hydraulic pump (11) for displacing pressure medium between at least two base point adjusting devices (4A, 4B), the hydraulic pump (11) in the controllable connection (10) is integrated.

9. Suspension system according to one of claims 6 to 8, characterized in that a locking member (13A, 13B; 19A, 19B) is arranged between the hydraulic pump (11) and one of the hydraulic cylinders (12A, 12B).

10. Suspension system according to one of claims 6 to 9, characterized in that in each case between the hydraulic pump (11) and the hydraulic cylinder (12A, 12B) a line (14A, 14B) to a Druckmit- Telreservoir (15) branches, which can be locked against the pressure medium reservoir (15) via a locking member (16A, 16B; 19A, 19B).

11. Suspension system according to one of claims 6 to 10, characterized in that a pressure intensifier (20) is arranged between the hydraulic pump (11) and a hydraulic cylinder (12A, 12B) of a foot point adjusting device (4A, 4B).

12. Suspension system according to claim 1, characterized in that the foot point adjustment device (4A, 4B) can be controlled electromechanically

13. Suspension system according to one of claims 1 to 12, characterized in that a spring-damper device (3A, 3B) has at least one damping element (5A, 5B) and a mechanical spring (6A, 6B) which are connected in parallel with one another.

14. Suspension system according to claim 13, characterized in that the foot point adjusting device (4A, 4B) is connected in series with the mechanical spring (6A, 6B).

15. Suspension system according to one of claims 1 to 12, characterized in that the spring-damper device is designed as a hydropneumatic suspension.

16. Suspension system according to claim 5, characterized in that the foot point adjusting device is connected in series with the hydropneumatic suspension.