STABILIZER ASSEMBLY FOR A TWO-TRACK VEHICLE

Abstract

The invention relates to a stabilizer assembly of a two-track vehicle for stabilizing a rolling movement, the stabilizer assembly being operable on at least two different spring characteristics, comprising a first and a second stabilizer half, each coupled to a wheel of the vehicle, wherein the first and the second stabilizer halves are coupled such that they can rotate relative to each other about their longitudinal axis by means of a spring element, whereby the stabilizer is operable with a first spring characteristic, and wherein the first and the second stabilizer halves can be hydraulically coupled such that they can rotate relative to each other about their longitudinal axis by means of a hydraulic actuator, whereby the stabilizer is operable using at least one second spring characteristic. The actuator comprises at least two work chambers which are filled with a hydraulic medium and coupled to each other by a fluid-conducting connection, and the actuator comprises a transmission unit which is designed such that a rotational movement of the stabilizer halves can be converted into a translational movement of an intermediate element arranged between the two work chambers, and a volume flow of the hydraulic medium from the one work chamber into the other work chamber can thus be produced.

Claims

1. A stabilizer assembly for a two-track vehicle for stabilizing a rolling movement, the stabilizer assembly being operable on at least two different spring characteristics, comprising a stabilizer comprising a first and a second stabilizer half each coupleable to a wheel of the vehicle, wherein the first and the second stabilizer halves are coupled such that they are rotatable relative to each other about their longitudinal axis by means of a spring element, whereby the stabilizer is operable with a first spring characteristic and wherein the first and the second stabilizer halves are hydraulically coupleable such that they are rotatable relative to each other about their longitudinal axis by means of a hydraulic actuator, whereby the stabilizer is operable with at least one second spring characteristic, the actuator comprising at least two work chambers which are filled with a hydraulic medium and coupled to each other by a fluid-conducting connection, wherein the actuator comprises a transmission unit which is designed such that a rotational movement of the stabilizer halves is convertible into a translational movement of an intermediate element arranged between the two work chambers, and a volume flow of the hydraulic medium from the one work chamber into the other work chamber is thus producible.

2. The stabilizer assembly according to claim 1, wherein the fluid-conducting connection of the work chambers comprises a frequency-selective valve by means of which the passage cross-section of the fluid-conducting connection is alterable depending on the oscillation frequency of the stabilizer assembly and the stabilizer is operable on a variable spring characteristic.

3. The stabilizer assembly according to claim 1, wherein an actuating element altering the passage cross-section of the fluid-conducting connection is open, closed or partially closed, whereby the stabilizer is operable on one or more further spring characteristics.

4. The stabilizer assembly according to claim 3, wherein the actuating element is closed in an unpowered state.

5. The stabilizer assembly according to claim 1, wherein the spring element is a torsion spring connected to at least one of the stabilizer halves and both stabilizer halves are coupled to each other by a rod element.

6. The stabilizer assembly according to claim 1, wherein the spring element is a torsion bar spring connecting the two stabilizer halves.

7. A method for operating a stabilizer assembly of a two-track vehicle designed according to claim 1, proceeding in the following steps: detecting a rolling movement of the vehicle and detecting a first damper default setting and subsequently establishing the fluid-conducting connection of the two work chambers depending on the damper default setting so that the rolling movement is damped by the hydraulic actuator.

8. The method according to claim 7, wherein the hydraulic damping is performed by a frequency-selective valve of the fluid-conducting connection depending on the oscillation frequency of the stabilizer halves and the stabilizer is operated on a variable spring characteristic.

9. The method according to claim 7, wherein the hydraulic actuator is deactivated upon detecting a second damper default setting, so that the fluid-conducting connection between the work chambers is interrupted and the rolling movement is supported by the spring element.

10. The method according to claim 7, wherein the damper default setting is adjusted depending on a driving mode and/or further boundary conditions.

Description

[0046] In the following, the invention will be further explained with the aid of two exemplary embodiments. All features described in more detail may be essential to the invention.

[0047] FIGS. 1 and 2 show a first exemplary embodiment of a stabilizer assembly, according to the invention, of a two-track vehicle in a sectional view through a longitudinal axis of the stabilizer assembly with an open position of a fluid-conducting connection and a closed position of this connection, respectively.

[0048] FIG. 3 shows a second exemplary embodiment of a stabilizer assembly according to the invention in a sectional view through the longitudinal axis of the stabilizer assembly.

[0049] FIG. 1 shows a first design in a sectional view through the longitudinal axis of the stabilizer assembly in a sectional view through the longitudinal axis of the stabilizer assembly of a two-track vehicle. Here, the stabilizer assembly comprises a first and a second stabilizer half 1, 2, each connected to a wheel (not depicted) of the vehicle. The two stabilizer halves 1, 2 are coupled by means of a rubber rod 3, which is designed as a torsion bar spring, such that they can rotate relative to each other about their longitudinal axis A. During rolling movements of the vehicle, the two stabilizer halves 1, 2 rotate relative to each other, with the rolling movement being cushioned or damped by the rubber rod 3. The stabilizer assembly is operated on a first spring characteristic by the rubber rod 3 depending on the spring stiffness of the rubber rod 3. Usually, the cushioning effect or the damping with such a torsion bar (also known as a passive stabilizer) as a spring element is comparatively low, i.e. the road feedback and thus also the rolling movements are damped less and are therefore more perceptible and more direct for a vehicle occupant (than is the case with an active stabilizer assembly).

[0050] It is further possible to couple the two stabilizer halves such that they can rotate relative to each other about their longitudinal axis A by means of a hydraulic actuator. This hydraulic actuator is arranged between the two stabilizer halves 1, 2 and comprises a rotation-translation converter 4, which is coupled to each stabilizer half 1, 2 via an interlocking fit. The rotation-translation converter 4 converts the rotational movement (about the longitudinal axis A) of the stabilizer halves 1, 2 into a translational movement along the longitudinal axis A of an intermediate element 5 of the actuator. The intermediate element 5 is arranged between two work chambers 6, 7 which are filled with a hydraulic medium and coupled to each other by a fluid-conducting connection 8, and disconnects them from each other. The passage cross-section of the fluid-conducting connection 8 can be actively altered by means of a valve 9. By means of a control unit which is not depicted here, the valve 9 can be actively controlled, particularly in an open-loop or closed-loop manner. It is also provided that the control unit controls the actuator by closing or opening the valve 9, particularly in an open-loop or closed-loop manner. If the valve 9 is open, the actuator is activated and the stabilizer is operated on at least one second spring characteristic, which is determined by the hydraulic damping of the actuator. The second spring characteristic has a higher damping level than the first load-deflection curve.

[0051] The maximum angle of rotation of the two stabilizer halves 6, 7 depends on the pitch of the gear teeth of the rotation-translation converter 4 and thus on the translational movability of the intermediate element 5. This translational movement of the intermediate element 5 and the associated compression of the hydraulic medium in the work chambers 6, 7 can be used to adjust the force-displacement characteristic or the spring rate of the stabilizer when the valve is open.

[0052] Since the valve 9 is closed in FIG. 1, there is no exchange of hydraulic medium between the two work chambers 6, 7. The two stabilizer halves 1, 2 are maximally coupled to each other and the stabilizer thus acts like a conventional torsion bar. It has the force-displacement characteristic of a conventional one-piece stabilizer, the spring rate of which is determined in this case by the rubber rod 3. The load curve of the stabilizer assembly with the valve 9 closed is shown in FIG. 1 by a dashed line L1.

[0053] FIG. 2 shows the stabilizer assembly from FIG. 1, with the difference that the valve 9 is now shown in an open position. If the vehicle experiences a rolling movement, a hydraulic exchange takes place between the two work chambers 6, 7 through the fluid-conducting connection 8. Depending on the load, the one stabilizer half 1 is rotated relative to the other stabilizer half 2 due to the overflow of the hydraulic medium from one of the work chambers 6, 7 into the other. The degree of the prevailing torsional stiffness is determined by the pitch of the gear teeth of the rotation-translation converter 4 and the associated volume flow of the hydraulic medium flowing into the work chambers 6, 7. When the valve 9 is open, the stabilizer is thus set to be softer, i.e. the two stabilizer halves 1, 2 can rotate relative to each other more easily than in case the valve 9 is closed. For achieving the desired force-displacement characteristic of the stabilizer when the valve 9 is open, the geometry of the rotation-translation converter (in particular its gear teeth geometry) is designed accordingly.

[0054] The load curve or the flux of force through the stabilizer assembly with open valve 9 is shown in FIG. 2 by a dashed line L2.

[0055] As already mentioned in the description, instead of or in addition to the valve 9, a frequency-selective valve can also be provided in the fluid-conducting connection 8, so that the damping is set depending on the oscillation frequency of the two stabilizer halves 6, 7.

[0056] If (only) a frequency-selective valve is used as an alternative to a valve 9 to alter the passage cross-section of the fluid-conducting connection 8, an active control or active activation or energization of the hydraulic actuator or the frequency-selective valve is not necessary. The hydraulic actuator then operates purely passively, i.e. without requiring external energy to actuate or operate the actuator. In this way, it is also possible to operate the stabilizer assembly on a variable spring characteristic or on a variable characteristic diagram without any external energy supply.

[0057] FIG. 3 shows a second design of a stabilizer assembly according to the invention. The difference between this and the first mentioned embodiment shown in FIGS. 1 and 2 lies in the geometrical configuration. However, the functional design is the same as in the first exemplary embodiment. The spring element in FIG. 3 is designed as a spiral spring 30, which is connected to a stabilizer half 1 in a rotationally fixed manner. The spiral spring 30 is arranged here such that its longitudinal axis or spring axis is parallel to the longitudinal axis A of the stabilizer assembly, or such that these are coincident. The two stabilizer halves 1, 2 are also connected to each other by a simple, rigid rod 10. The rod 10 is not designed as a spring element here.

[0058] In this case, too, the actuator comprises a rotation-translation converter 40 that converts the rotational movement of the stabilizer halves 1, 2 into a translational movement of an intermediate element 50 between two work chambers 60, 70. Also in this case, the two work chambers 60, 70 can be coupled to each other via a fluid-conducting connection 80. Here too, a valve 90 is arranged in the fluid-conducting connection 80, by means of which it is possible to switch the stabilizer assembly from the first spring characteristic to the second spring characteristic.

[0059] In the case of the valve 90 being closed, the spring force or damping of the stabilizer assembly is, in contrast to the first exemplary embodiment, predominantly dependent on the spring stiffness of the spiral spring 30. In the case of an open valve 90, the situation is the same as with the open valve 9 of the first embodiment.

[0060] Of course, it is also possible in this second embodiment to arrange a frequency-selective valve as an alternative or in addition to the valve 90 in order to ensure a variable spring characteristic.

[0061] It is also possible in both embodiments to provide a frequency-selective valve at the mentioned or another fluid-conducting connection 8, 80 of the stabilizer assembly, in addition to the valve 9, 90.

[0062] Furthermore, it is preferably provided in both exemplary embodiments that switching between the first and the second spring characteristic of the stabilizer assembly, i.e. the switching of the valve 9, 90, is dependent on external boundary conditions or on a set driving mode. More details on these boundary conditions are explained in the description above.

[0063] In this way, a switchable semi-active stabilizer assembly can be provided in a simple manner, in which neither an external pumping device nor a motor is required.

LIST OF REFERENCE SIGNS

[0064] 1 stabilizer half [0065] 2 stabilizer half [0066] 3 rubber rod [0067] 4 rotation-translation converter [0068] 5 intermediate element [0069] 6 work chamber [0070] 7 work chamber [0071] 8 fluid-conducting connection [0072] 9 valve [0073] 10 rod [0074] 30 spiral spring [0075] 40 rotation-translation converter [0076] 50 intermediate element [0077] 60 work chamber [0078] 70 work chamber [0079] 80 fluid-conducting connection [0080] 90 valve [0081] A longitudinal axis [0082] L1 flux of force [0083] L2 flux of force