Switchable Stabilizer Assembly of a Vehicle

Abstract

A switchable stabilizer assembly of a vehicle, in particular for roll stabilization. The stabilizer assembly includes a first stabilizer half and a second stabilizer half, both coupled to a wheel of the vehicle, where the first and second stabilizer halves are coupled rotatably relative to each other about their longitudinal axis by a hydraulic actuator. The actuator has at least two working chambers filled with a hydraulic medium and has at least one fluid-conducting connection of variable flow cross section between the at least two working chambers. The working chambers are not elastically deformable. Instead, a spring element is arranged in the at least two working chambers and/or in at least two further working chambers of the actuator and is supported between a rotor and a stator of the actuator. The flow cross section of the fluid-conducting connection can be varied depending on the vibration frequency of the stabilizer assembly.

Claims

1. A switchable stabilizer assembly of a vehicle, comprising: a first stabilizer half and a second stabilizer half, wherein the first stabilizer half and the second stabilizer half are each coupled with a respective wheel of the vehicle; and a first hydraulic actuator, wherein the first and the second stabilizer halves are coupled rotatably against each other around a respective longitudinal axis by the first hydraulic actuator, wherein the first hydraulic actuator has at least two working chambers filled with a hydraulic medium, wherein the first hydraulic actuator has a first fluid-conducting connection between the at least two working chambers, and wherein a flow cross section of the first fluid-conducting connection is variable; wherein the at least two working chambers of the first hydraulic actuator are not elastically deformable and wherein a first spring element is disposed in the at least two working chambers of the first hydraulic actuator and/or in at least two additional working chambers of the first hydraulic actuator and is supported between a rotor and a stator of the first hydraulic actuator; wherein the flow cross section of the first fluid-conducting connection is variable as a function of a vibration frequency of the switchable stabilizer assembly.

2. The switchable stabilizer assembly according to claim 1, wherein the flow cross section of the first fluid-conducting connection is variable by a frequency-selective control element.

3. The switchable stabilizer assembly according to claim 1, wherein the first stabilizer half is non-rotatably connected with the rotor and wherein the second stabilizer half is non-rotatably connected with the stator.

4. The switchable stabilizer assembly according to claim 1, wherein a second hydraulic actuator is connected in series with the first hydraulic actuator.

5. The switchable stabilizer assembly according to claim 4, wherein a third hydraulic actuator is connected in series with the first hydraulic actuator and/or with the second hydraulic actuator and wherein the third hydraulic actuator does not have a spring element.

6. The switchable stabilizer assembly according to claim 4, wherein the second hydraulic actuator has a second spring element and wherein the first and second spring elements have a respective variable spring rate.

7. The switchable stabilizer assembly according to claim 1, wherein a control element that changes the flow cross section of the first fluid-conducting connection is coupled with a control unit, and is open, closed or partially closed depending on boundary conditions.

8. The switchable stabilizer assembly according to claim 1, wherein a control element that changes the flow cross section of the first fluid-conducting connection is coupled with an external actuating device, and is open, closed or partially closed depending on an actuation of the external actuating device.

9. The switchable stabilizer assembly according to claim 7, wherein the control element is closed in a de-energized state.

10. The switchable stabilizer assembly according to claim 1 further comprising a second fluid-conducting connection between the at least two working chambers of the first hydraulic actuator.

11. The switchable stabilizer assembly according to claim 10, wherein a control element that changes a flow cross section of the second fluid-conducting connection is coupled with a control unit, and is open, closed or partially closed depending on boundary conditions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG. 1 and FIG. 2 each here present a schematic illustration of the construction according to the invention in a cross section of an actuator.

[0058] FIG. 3, FIG. 4 and FIG. 5 show a schematic, three-dimensional view of stabilizer assemblies according to the invention.

[0059] FIG. 6 and FIG. 7 show two embodiments of a second fluid-conducting connection in a cross section of the actuator.

[0060] FIG. 8 and FIG. 9 show the embodiment of an actuator of a stabilizer assembly according to the invention, in which two working chambers are fluidically connected with a frequency-selective valve.

DETAILED DESCRIPTION OF THE DRAWINGS

[0061] FIG. 1 presents a cross section through a hydraulic, semi-active actuator of a stabilizer assembly according to the invention. This actuator 1 couples a first with a second stabilizer half (neither shown) so that they can be rotated against each other around their longitudinal axis. The first stabilizer half is here non-rotatably connected with a rotor 2 of the actuator 1, and the second stabilizer half with a stator 3 of the actuator 1. The hydraulic actuator 1 itself has two working chambers 4, 5 filled with a hydraulic fluid, wherein a fluid-conducting connection 6 is arranged between the mentioned working chambers 4, 5. The flow cross section of the fluid-conducting connection 6 can be actively varied by means of a valve 7.

[0062] According to the invention, the mentioned working chambers 4, 5 are for their part not elastically deformable; instead, in each case spring element 10 is arranged in two additional working chambers 8, 9 of the actuator 1, and supported between the rotor 2 and stator 3 of the actuator 1. The actuator or stabilizer is in an unloaded position or in the zero position on FIG. 1, in which the two stabilizer halves are not twisted opposite each other. The valve 7 can be adjusted between an open, closed and intermediate position. The hydraulic medium can flow over into the working chambers 4, 5 with the valve 7 open. The maximum angle of twist for the two stabilizer halves or between the rotor 2 and stator 3 depends on the number of stops 3a formed by the stator 3. The spring elements 10 according to the invention, which are each supported on the rotor 2 and stator 3, can be used to set the force-path characteristic curve or spring rate of the stabilizer (with the valve open). Since the valve 7 is closed on FIG. 1, no exchange of hydraulic medium takes place between the two working chambers 4, 5. The two stabilizer halves are here maximally coupled with each other, and the stabilizer thus acts like a conventional torsion bar. The latter has the force-path course of a conventional, integral stabilizer. Therefore, if the valve is closed, the stabilizer is in a sport mode. The sport mode makes sense in particular if a dynamic and agile drive is desired, for example while maneuvering curves.

[0063] If the valve 7 is open as depicted on FIG. 2, hydraulic medium can be exchanged from one working chamber 5 into the other working chamber 4 (and vice versa, of course). Depending on the load, the overflow of hydraulic medium from one of the working chambers 4, 5 into the other thus causes the one stabilizer half or the rotor 2 to twist relative to the other stabilizer half or to the stator 3. The spring rate of the spring elements 10 here determines how high the prevailing torsional stiffness is. With the valve 7 open, the stabilizer is thus in a softer setting, i.e., the two stabilizer halves can twist opposite each other more easily than with the valve 7 closed. In order to reach the desired force-path characteristic curve of the stabilizer with the valve 7 open, the spring elements are configured accordingly in terms of their material and geometry.

[0064] This makes it easy to provide a switchable, semi-active stabilizer assembly which requires neither an external pumping device nor a motor.

[0065] FIG. 3 exemplarily shows a stabilizer assembly according to the invention in a three-dimensional illustration. The actuator 1 already discernible on FIG. 1 and FIG. 2 is here shown, and couples the two stabilizer halves 11, 12 so that they can be twisted relative to each other. Both stabilizer halves 11, 12 are here connected with a vehicle wheel (not visible) at their outer ends 11a, 12a and by way of specific mountings 13 with a vehicle body (also not sketched in). The valve 7 can open, close or only partially close the mentioned fluid-conducting connection 6 between the two working chambers 4, 5, and is here actuated or set by an electrical signal in an electrical line 14. The actuation can here take place via a control unit depending on outside boundary conditions or via an actuating device, for example which is switched by the driver him or herself.

[0066] FIG. 4 shows another embodiment of the stabilizer assembly according to the invention. Apart from an already described actuator 1 from FIG. 1 and FIG. 2, another second actuator 15 is arranged or connected in series to the latter. As opposed to the described actuator 1, none of the spring elements 10 according to the invention are arranged in the second actuator 15, as evident on FIG. 5 (in which the housing of the actuators is not shown). A stabilizer half 11 is here fixedly connected with the rotor 2 of the first actuator 1, while the other stabilizer half 12 is fixedly connected with a rotor 16 of the second actuator 15. The two actuators 1, 15 comprise a shared housing, which for its part also comprises the stators 3 or stops 3a. The stators 3 or the shared housing of the two actuators 1, 15 is not fixedly connected with any stabilizer half 11, 12.

[0067] Both actuators have a valve 7, 16, which can separate or establish a fluid-conducting connection 6 between the respective working chambers 4, 5, 17, 18. The depicted series connection between the two actuators 1, 15 makes it possible to switch between a total of three different driving modes or stabilizer stiffnesses or spring rates. For example, if both valves 7, 16 of both actuators 1, 15 are closed, the two stabilizer halves 11, 12 are maximally coupled together, and the stabilizer acts like an integral torsion bar. This comparatively hard or stiff arrangement of the stabilizer makes sense in particular when driving around curves for reasons of driving dynamics and driving safety, and is thus referred to as the sport mode. By contrast, if the valve 7 of the first actuator 1 (i.e., the actuator 1 with the spring elements 10 according to the invention) is open and the valve 16 of the second actuator 15 is closed, the force-path course of the stabilizer depends on the spring rate of the spring elements 10. Because the stabilizer has a comparatively soft or less stiff configuration, the vehicle can be correspondingly more comfortable to drive. However, if it is desired that the two stabilizer halves 11, 12 be decoupled from each other, which makes sense in particular on uneven terrain, the stabilizer can be switched into an off-road mode. To this end, the valve 16 of the second actuator 15 is opened, and the valve 7 of the first actuator 1 is closed. The hydraulic fluid can in this way freely communicate or flow between the two working chambers 17, 18, wherein the two stabilizer halves 11, 12 are nearly decoupled.

[0068] FIG. 6 and FIG. 7 show a cutout from a schematically depicted cross section of the actuator 1 with exemplary embodiments of a bypass channel 19 or an overflow recess 20. To this end, an additional connection channel 19 is arranged in direct proximity to the rotor 3 located in an unloaded or immovable position between the two working chambers 4, 5. In this case, an unloaded position means that the stabilizer is in the zero position or design position. It is just as likely possible, as shown on FIG. 7, to arrange a narrow overflow recess 20 on the inner diameter 3b of the stator 3 in direct proximity to the idle rotor 2 instead of a connection channel 19. At high-frequency loads or twists with low amplitudes of the kind usually encountered on rough roads or while driving over cobblestones, a recess 20 or this type of channel 19 enables a small rotational angle of the rotor, and hence an improved ride comfort or remaining comfort, even in the stiff or hard switching mode or position. The mentioned remaining comfort varies depending on the prevailing angle of twist of the rotor 2 up to which a fluid exchange is possible within the channel 19 or overflow recess 20, and thus depending on the position of the entry or exit of the hydraulic medium in the channel 19 or in the overflow recess 20 on the inner diameter of the stator 3b.

[0069] FIG. 8 and FIG. 9 show the embodiment of an actuator of a stabilizer assembly according to the invention, in which two working chambers 4, 5 are fluidically connected with a frequency-selective valve 21.

[0070] Such a frequency-selective control element can enable a frequency-selective damping.

[0071] A frequency-selective valve can detect the vibration frequencies in the hydraulic medium and automatically open or close them in specific frequency ranges. To this end, the damping force is preferably configured by the control element of the fluid chambers to the movement frequency of the vehicle or movement frequency of the stabilizer movement or rotor movement in such way as to achieve a low damping force at higher frequencies (in particular frequencies in a range higher than 2-5 Hz), and a high damping force at lower frequencies (in particular frequencies in a range lower than 2-5 Hz).

[0072] The valve 21 itself consists of two chambers 21a, 21b, which each comprise a movable or displaceable piston 21c. In addition, a fluid line 22 runs from each chamber 21a, 21b of the valve 21 back into the working chambers 4, 5 of the actuator (also referred to as bypass lines 22). These bypass lines 22 or fluid lines 22 are here designed with the help of a check valve 26 in such a way as to allow the fluid to flow in only one direction, specifically in the direction of the respective working chamber 4, 5. Furthermore, a pressure compensation valve 25 is arranged on the fluid-conducting connection 6 for pressure compensation of the system.

[0073] Depending on the twisting direction of the stabilizer halves relative to each other, one of the two chambers 21a, 21b of the valve 21 is always in operation. For this reason, the mode of action of the right chamber 21b will be described below; however, it manifests itself in an equivalent fashion to the left chamber 21a given a different twisting direction of the stabilizer halves relative to each other.

[0074] The piston 21c in the valve 21 covers or closes the mentioned bypass line 22 in a specific position. In addition, the piston 21c forms two working spaces 21ba, 21bb within the chamber 21b of the valve 21. These two working spaces 21ba, 21bb are for their part fluidically connected with each other by a throttle 23. These throttles 23 are also referred to as small throttles, and arranged inside of the valve 21 for pressure compensation.

[0075] Arranged so as to bridge the valve 21 is an additional throttle 24 also referred to as large throttle 24, through which the hydraulic medium can also flow.

[0076] The operating principle of the frequency-selective valve 21 inside of the stabilizer assembly will be explained in more detail in the following sections and Figures.

[0077] Let it be noted beforehand that the valve 7 (i.e., a valve that is not frequency selective) is additionally arranged to even enable or entirely prevent a fluidic connection between the working chambers 4, 5 of the actuator. If the valve 7 is closed instead, the fluid-conducting connection 6 of the two working chambers 4, 5 is locked or blocked. The frequency-selective valve 21 is then not used, and the stabilizer assembly acts as a conventional, passive stabilizer.

[0078] A situation in which the valve 7 is thus open will be described in the following explanation.

[0079] FIG. 8 here shows the situation in which the stabilizer halves move relative to each other in the higher-frequency range or in which the rotor of the swivel motor vibrates at a higher frequency. The fluid or hydraulic medium is here initially conducted via the large throttle 24. However, this large throttle 24 only allows a limited volume flow per unit of time. The remaining fluid, which no longer flows through via the large throttle 24, is passed through the frequency-selective valve 21. As the pressure rises (i.e., at higher frequencies), the piston 21c of the valve 21 moves in such a way as to allow the fluid to flow through the bypass line 22. This reduces the damping force, since the resistance through the bypasses 22 is distinctly lower, and more fluid can pass through the bypass 22 than through the large throttle 24.

[0080] FIG. 9 shows the situation in which the valve 7 is open for establishing a fluid-conducting connection of the working chambers 4, 5 relative to each other, and the stabilizer halves or rotor of the actuator move at low frequencies.

[0081] The fluid can flow through the large throttle 24 at a lower pressure or at lower frequencies, while the piston 21c of the valve 21 is at a position in which it seals the bypass line 22. Since the resistance of the large throttle 24 is distinctly higher than the resistance of the bypass lines 22, the damping force in the low-frequency or lower-frequency vibration range of the stabilizer assembly is higher than in the higher-frequency range.

LIST OF REFERENCE CHARACTERS

[0082] 1 Actuator [0083] 2 Rotor [0084] 3 Stator [0085] 3a Stop [0086] 3b Inner diameter of the stator [0087] 4 Working chamber [0088] 5 Working chamber [0089] 6 Fluid-conducting connection [0090] 7 Valve [0091] 8 Working chamber [0092] 9 Working chamber [0093] 10 Spring element [0094] 11 Stabilizer half [0095] 11a End of the stabilizer half [0096] 12a End of the stabilizer half [0097] 12 Stabilizer half [0098] 13 Mounting [0099] 14 Line [0100] 15 Second actuator [0101] 16 Valve [0102] 17 Working chamber [0103] 18 Working chamber [0104] 19 Channel [0105] 20 Overflow recess [0106] 21 Frequency-selective valve [0107] 21a Chamber of the frequency-selective valve [0108] 21b Chamber of the frequency-selective valve [0109] 21c Piston [0110] 22 Bypass line [0111] 23 Throttle [0112] 24 Throttle [0113] 25 Pressure compensation valve

[0114] 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.