Leveling system

Abstract

A leveling system for a vehicle includes a electromechanical actuator including an electric motor (102), a gear reduction unit (104) selectively driven by the electric motor, a rotary to linear motion conversion mechanism (108) and a clutch (106). The rotary to linear motion conversion mechanism includes a first rotatable member adapted to be coupled to one of a sprung mass and an unsprung mass of the vehicle. A linearly translatable member of the rotary to linear motion conversion mechanism is adapted to be coupled to the other sprung and unsprung masses. The clutch is operable in an open mode or a torque transferring mode where power is transmitted between the electric motor and the rotary linear motion conversion mechanism to change a distance between the sprung mass and the unsprung mass.

Description

LEVELING SYSTEMFIELD

[0001] The disclosure generally relates to a vehicle suspension system. More particularly, a leveling system for adjusting the height of the vehicle relative to the road is discussed.BACKGROUND

[0002] Over the years of automotive vehicle development, it has been recognized that it may be beneficial to have a suspension system operable to change a ride height of the vehicle. City buses have been equipped with systems allowing the vehicle to “kneel” adjacent to a curb or sidewalk to minimize the distance from a lower stair of the bus to the ground at the time of the passenger ingress and egress. While the systems have been effective, such systems are often very complex, heavy and not necessarily structurally robust.

[0003] Many of the known systems include compressors, pumps, valves, at least one tank, accumulators, and pressurized conduits such as tubes or lines extending along and across the vehicle. Some of these systems may include air bags, or bladders that may be susceptible to leakage or puncture. Additionally, it has been found that response times to a command for a height change may be longer than desired. Additionally, the energy consumption of known systems may be undesirably high. Known systems are often bulky and voluminous requiring an undesirably large packaging envelope for the various components of the leveling system. Accordingly, a need exists for an improved leveling system having reduced costs and complexity.SUMMARY

[0004] A leveling system for a vehicle includes an electromechanical actuator including an electric motor, a gear reduction unit selectively driven by the electric motor, a rotary to linear motion conversion mechanism and a clutch. The rotary to linear motion conversion mechanism includes a first rotatable member adapted to be coupled to one of a sprung mass and an unsprung mass of the vehicle. A linearly translatable member of the rotary to linear motion conversion mechanism is adapted to be coupled to the other of the sprung and unsprung masses. The clutch is operable in a torque transferring modeto transmit power between the electric motor and the rotary linear motion conversion mechanism to change a distance between the sprung mass and the unsprung mass.

[0005] A method of changing a ride height of a vehicle comprises positioning an electromechanical actuator between a sprung mass and an unsprung mass of a vehicle. The electromechanical actuator includes an electric motor, a gear reduction unit selectively driven by the electric motor, a rotary to linear motion conversion mechanism selectively driven by the electric motor, and a clutch. The rotary to linear motion conversion mechanism includes a rotatable member adapted to be coupled to one of the sprung and unsprung masses and a linearly translatable member adapted to be coupled to the other of the sprung and unsprung masses. The clutch is positioned to selectively supply and interrupt power transmission between the electric motor and the rotary to linear motion conversion mechanism. The method further includes energizing the electric motor when the clutch is in an open mode, rotating the motor at a predetermined operating speed while the clutch is in the open mode, subsequently operating the clutch in a torque transferring mode, and changing a distance between the sprung mass and the unsprung mass when the electric motor is energized and the clutch is in the torque transferring mode.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0007] Figure 1 is a schematic of an exemplary vehicle equipped with a leveling system constructed in accordance with the teachings of the present disclosure;

[0008] Figure 2 is a schematic depicting a front suspension assembly including electromechanical actuators of a portion of the leveling system;

[0009] Figure 3 is a schematic of a rear suspension assembly equipped with electromechanical actuators of at least a portion of the leveling system of the present disclosure;

[0010] Figure 4 is a fragmentary perspective view depicting a front corner implementation of the leveling system;

[0011] Figures 5-8 are schematics depicting various configurations of components and their relative positions within different embodiments of the leveling system electromechanical actuators;

[0012] Figure 9 includes a fragmentary perspective view of another electromechanical actuator and its associated schematic depicting various components of the electromechanical actuator;

[0013] Figure 10 is a perspective view of an alternate embodiment electromechanical actuator including a helper spring;

[0014] Figure 11 is a cross-sectional view of the actuator with helper spring depicted in Figure 10;

[0015] Figure 12 is a perspective view of another alternate embodiment electromechanical actuator along with its associated schematic;

[0016] Figure 13 is a fragmentary perspective view of the electromechanical actuator depicted in Figure 12;

[0017] Figure 14 is a fragmentary perspective view of another alternate embodiment electromechanical actuator including a linkage assembly with the actuator depicted in a retracted position;

[0018] Figure 15 is a fragmentary perspective view of the electromechanical actuator depicted in figure 14 with the actuator shown in an extended position;

[0019] Figure 16 is a perspective view of another alternate embodiment electromechanical actuator including the linkage assembly;

[0020] Figure 17 is a perspective view of the actuator depicting Figure 16; and

[0021] Figure 18 is a fragmentary cross-sectional view of the actuator depicted in Figures 16 and 17.

[0022] In the drawings, reference numbers may be reused to identify similar and / or identical elements.DETAILED DESCRIPTION

[0023] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0024] Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0025] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0026] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0027] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0028] Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0029] Referring to Figure 1 , an exemplary vehicle 10 includes a rear suspension 12, a front suspension 14, and a body 16. The rear suspension 12 is adapted to operatively support the vehicle's rear wheels 18. Rear suspension 12 is operatively connected to the body 16 by a pair of dampers 20 and a pair of helical coil springs 22. Similarly, front suspension 14 operatively supports the vehicle’s front wheels 24. The front suspension is operatively connected to body 16 by a second pair of dampers 26 and by a pair of helical coil springs 28. Dampers 20 and 26 serve to dampen the relative motion of the unsprung portion (i.e., front and rear suspensions 14 and 12, respectively) and the sprung portion (i.e., body 16) of vehicle 10. While the vehicle 10 has been depicted as a passenger car having front and rear suspension or axle assemblies, dampers 20 and 26 may be used with other types of vehicles or machinery, or in other types of applications such as vehicles incorporating independent front and / or independent rear suspension systems. Further, the term “damper”, as used herein, is meant to refer to dampers and damper systems in general and thus will include MacPherson struts. It should also be appreciated that the scope of the subject disclosure is intended to include leveling systems associated with stand-alone dampers 20 and coil-over dampers 26.

[0030] As depicted in Figures 1 , 2 and 4, a leveling system 29 includes an electromechanical actuator or an electromechanical spacer 30 positioned between an upper spring seat 32 and an upper mount 34 at each corner of front suspension 14. In an alternate arrangement, electromechanical actuators 30a are positioned between lower spring seats 36 and lower mounts 38, in lieu of electromechanical actuators 30.

[0031] Figures 1 and 3 depict a portion of leveling system 29 in relation to rear suspension 12. In a first configuration, a first set of electromechanical actuators 30b are implemented. Each actuator 30b is positioned between an upper spring seat 40 of spring22 and an upper mount 42 associated with body 16. Alternatively, electromechanical actuators 30c may be installed in lieu of electromechanical actuators 30b. For example, each electromechanical actuator 30c is positioned in rear suspension 12 between a lower spring seat 44 and a lower mount 46. Each electromechanical actuator 30, 30a, 30b, 30c may be individually controlled to change its overall length to change the ride height of the vehicle.

[0032] It may be desirable to adjust the ride height of the vehicle for a variety of reasons. For example, in relation to the rear axle, it may be beneficial to selectively actuate electromechanical actuators 30b or 30c to compensate for load added to the trunk or bed of the vehicle. Other considerations may relate to improving the ride comfort of the passenger, maintaining ground clearance for a fully loaded vehicle, easing loading and unloading of cargo from the vehicle, and adjusting an angle of stall for efficient and passive battery cooling.

[0033] In relation to the front axle, it may be desirable to selectively actuate electromechanical actuators 30 or 30a to modify the ground clearance of the front end of the vehicle to account for speed bumps, driveways and steep angle approaches. It may be desirable to adjust all electromechanical actuators simultaneously to lower the vehicle in an appropriate driving situation to reduce air resistance and increase vehicle operational efficiency. When rough roads are detected, it may be beneficial to raise the ride height to protect the car body and allow the shock absorbers to account for road surface undulations. It may also be beneficial to implement a controller operable to maintain a predetermined ride height of the vehicle regardless of the loading of the vehicle to due to passengers or cargo to maintain a desired ride comfort and operation characteristics.

[0034] As depicted in Figures 5-8, the electromechanical actuators previously described may have components arranged in different sequences to address individual vehicle configuration parameters. Figure 5 depicts an electromechanical actuator identified at reference numeral 100 that may be implemented as any one of previously introduced electromechanical actuators 30, 30a, 30b, 30c. Electromechanical actuator 100 includes an electric motor 102, a gear reduction unit 104, a clutch 106, and a rotary to linear conversion mechanism 108. Electric motor 102 may be of any configuration including brushed or brushless. Electric motor 102 includes an output shaft 110 rotating at a speed directly proportional to the speed of the motor. Gear reduction unit 104 may comprise any number of mechanical advantage machines including spur gearsets,helical gearsets, ring and pinion gearsets, planetary gearsets, pulleys, belts, wedges, or any other suitable machine for reducing the speed and increasing the output torque of the input provided to gear reduction unit 104.

[0035] An output shaft 112 drivingly connects gear reduction unit 104 with an input member 114 of clutch 106. An output member 116 of clutch 106 is drivingly coupled to rotary to linear conversion mechanism 108. It is contemplated that clutch 106 is configured in a normally open condition where torque is not transferred between input member 114 and output member 116. Clutch 106 is selectively operable in a closed or torque transferring mode when input member 114 is drivingly coupled to output member 116. Clutch 106 may be a dog type clutch exhibiting only on and off characteristics. Alternatively, clutch 106 may be a variable torque transfer clutch where an amount of relative rotation between input member 114 and output member 116 is controlled to produce a desired magnitude of torque provided to rotary to linear conversion mechanism 108.

[0036] In one arrangement, clutch 106 is magnetorheological clutch. In this configuration, clutch 106 includes a housing 120 containing a magnetorheological fluid 122. Magnetorheological fluid includes ferromagnetic particles suspended in oil. When the magnetorheological fluid is exposed to a magnetic field, the ferromagnetic particles become aligned and increase the viscosity of the magnetorheological fluid. The viscosity may be varied based on the intensity of the magnetic field. Use of magnetorheological fluid within clutch 106 provides a highly controllable clutch that does not involve a direct frictional engagement of components. Concerns regarding sprag or clutch plate wear are alleviated. Additionally, the magnetorheological clutch functions without reflected inertia and without torque ripples. A source of a magnetic field (not shown) is positioned proximate magnetorheological fluid 122. Accordingly, the viscosity of magnetorheological fluid 122 may be varied in response to the magnitude of magnetic field applied.

[0037] Rotary to linear motion conversion mechanism 108 may be configured in a number of ways. For example, the mechanism may be configured as a helical screw and nut arrangement, a power screw, a ball screw, a rack and pinion, or the like. Rotary to linear motion conversion mechanism 108 is operable to change the overall length of electromechanical actuator 100.

[0038] Beneficially, clutch 106 drivingly decouples gear reduction unit 104 from rotary to linear motion conversion mechanism 108 when in the open mode of operation. Typically, a gearbox or gear reduction unit exhibits a relatively high mechanical efficiencyexceeding 94% efficiency. On the contrary, typical lead screws or power screws are relatively inefficient mechanisms operating in the 35%-45% efficiency range. Accordingly, it may be desirable to decouple electric motor 102 from the lower efficiency mechanical advantage rotary to linear motion conversion mechanism 108 when advantageous. In this manner, electric motor 102 may be initially energized to rotate only the components associated with the motor and gear reduction unit 104 while clutch 106 is in the open operating mode. A minimal resistance to start up exists, thereby requiring a minimal motor starting torque. Applicant’s invention allows the use of a low-cost electric motor that is relatively small due to the low starting torque requirement. Once electric motor 102 rotates at a predetermined operating speed, clutch 106 may be actuated to transfer torque to rotary to linear motion conversion mechanism 108 at change a distance between the sprung and unsprung masses of the vehicle.

[0039] Figure 6 depicts an alternate electromechanical actuator at reference numeral 150. Electromechanical actuator 150 is substantially similar to electromechanical actuator 100 but the components are rearranged relative to one another. In this example, electric motor 102 directly drives input member 114 of clutch 106. Gear reduction unit 104 is downstream of clutch 106. The output from gear reduction unit 104 drives rotary to linear motion conversion mechanism 108. This arrangement may be preferred when attempting to reduce the size of electric motor 102 as only the electric motor components and the input member 114 need be rotated at electric motor startup.

[0040] Figure 7 represents another electromechanical actuator identified at reference numeral 160. Electromechanical actuator 160 is substantially similar to electromechanical actuator 100 with the addition of another gear reduction unit 162 interposed between clutch 106 and rotary linear to motion conversion mechanism 108. Depending on the load to be raised and the gear ratios employed in gear reduction unit 104 and rotary to linear motion conversion mechanism 108, additional gear reduction unit 162 may be required to lift the desired load.

[0041] Figure 8 illustrates yet another electromechanical actuator identified at reference numeral 170. This arrangement illustrates the possibility of implementing several groups of gearsets or gear reduction units on either side of clutch 106. It may be desirable to incorporate additional gearsets 172, 174, 176, 178, 180 to achieve certain packaging constraints that may exist at a vehicle wheel end while obtaining a desired overall mechanical advantage prior to supplying torque to rotary to linear motion conversion mechanism 108.

[0042] Figure 9 depicts another alternate embodiment electromechanical actuator 200. As previously mentioned, any number of gear reduction units having various gear ratios may be employed. The specific gear ratios mentioned hereafter are merely exemplary. Actuator 200 includes an electric motor 202 driving a gear reduction unit 204 providing a 3:1 mechanical advantage to a magnetorheological clutch 206. Four separate gearsets are positioned downstream of clutch 206 and arranged in series. Namely a first stage gear reduction unit 208 provides a 2.1 :1 mechanical advantage to a second stage gear reduction unit 210 providing a 2.5:1 gear reduction. A third stage gear reduction unit 212 receives output torque from second stage gear reduction unit 210. Third stage gear reduction unit 212 provides a 3:1 reduction ratio. A fourth stage gear reduction unit 214 also provides a 3:1 gear reduction. Output from fourth stage gear reduction unit 214 is provided to a lead screw 216 that converts rotary motion to linear motion and changes the overall length electromechanical actuator 200.

[0043] In the example depicted, lead screw 216 is constructed as a 72x4, 4 lead arrangement. Lead screw 216 includes a helical drive screw 218 threadedly engaged with a nut 220. Nut 220 is rotatable by an output member of fourth stage gear reduction unit 214 and drive screw 218 is an axial translatable member. It should be appreciated that this arrangement may be reversed, if desired. A strut tower connector 222 is fixed for axial translation with drive screw 218. Torque retaining bars 224 may be provided to restrict rotation of strut connector 222.

[0044] Figure 10 depicts another alternate embodiment electromechanical actuator at reference numeral 300. This embodiment differs from the others primarily in that a compression or helper spring 302 is positioned within a rotary to linear motion conversion mechanism 310. A strut tower connector 304 is fixed for axial translation with a lead screw 306. A nut 308 in combination with lead screw 306 forms the rotational to linear motion conversion mechanism 310. Spring 302 urges lead screw 306 away from nut 308 thereby reducing the amount of torque required to be applied to rotary to linear conversion mechanism 310 to lift a load. Adding the spring 302 inside the lead screw mechanism may help improve stability and reduce power consumption.

[0045] It should be appreciated that any one of the previously described electromechanical actuators may be constructed without a clutch. A clutch need not be provided to allow the electric motor to be directly drivingly coupled to one more gear reduction units and a rotary to linear motion conversion device. Such a configuration may require a larger motor or more energy supplied to a given motor but the overall length ofthe electromechanical actuator will be controllable thereby allowing the ride height of the vehicle to be changed.

[0046] It is also contemplated that alternate mechanical movement devices may be installed in addition to or in lieu of the power screw / lead screw rotary to linear motion conversion devices previously described. In particular, Figures 12 and 13 depict an alternate electromechanical actuator 400 including an in-line drive mechanism providing a different packaging option and mechanical advantage choice. Actuator 400 includes an electric motor 402 and a planetary gearset 404 that is driven by electric motor 402. A magnetorheological clutch 406 is positioned further downstream in series and in receipt of an output from planetary gearset 404. A worm gearset 408 is positioned on the opposite side of magnetorheological clutch 406 as planetary gearset 404. Worm gearset 408 provides a torque input to a lead screw 410. Lead screw 410 is configured as a rotatable nut 412 having a fixed axial position threadingly engaged with a linearly translatable drive screw 414. Worm gearset 408 includes a worm 415 drivingly engaged with a worm wheel 417. Worm wheel 417 is formed on an outer perimeter of nut 412. Electromechanical actuator 400 is positioned between an upper spring seat 416 and an upper mount 418 that is fixed to a vehicle body. As previously mentioned, electromechanical actuator 400 may also be associated with a lower mount positioning on the vehicle.

[0047] In yet another alternate example, an electromechanical actuator 500 includes a mechanical linkage arrangement having an end coupled to one of the spring seats or mounts previously described. An opposite end of the mechanical linkage arrangement is driven by an electric motor with optional additional mechanical advantage devices. In the embodiment shown in Figures 14 and 15, actuator 500 includes an electric motor 502 drivingly coupled to a planetary gearset 504. A magnetorheological clutch 506 is driven by planetary gearset 504. A spur gearset 508 is coupled to an output of magnetorheological clutch 506. A ball screw mechanism 510 is downstream of and in driving engagement with spur gear 508. A linkage assembly 520 is driven by ball screw mechanism 510. A first end 522 of linkage assembly 520 is rotatably coupled to a housing 524 of ball screw mechanism 510. An opposite second end 526 of linkage assembly 520 is coupled to a linearly translatable drive screw 528 of ball screw mechanism 510. Second end 526 is fixed to or at least coupled to an upper body mount 530. Other portions of linkage assembly 520 are moveably coupled to an upper spring seat 532. Figure 14 depicts ball screw mechanism 510 in a retracted position with upper mount 530 beingminimally spaced apart from upper spring seat 532. Figure 15 depicts ball screw mechanism 510 and linkage assembly 520 in an extended or actuated position where upper mount 530 is significantly spaced apart from upper spring seat 532.

[0048] Figures 16-18 illustrate another alternate embodiment electromechanical actuator identified at reference numeral 600. Electromechanical actuator 600 is positioned between a lower spring seat 616 and an unsprung mass of the vehicle. Actuator 600 includes an electric motor 602 driving a gear reduction unit 604. Gear reduction unit 604 may provide a mechanical advantage ratio of 6:1 . An output from gear reduction unit 604 is provided to a magnetorheological clutch 606. On the opposite side of clutch 606 is a spur gearset 608 providing a 3:1 drive ratio. An output of the spur gearset 608 is provided to a ball screw 610. A linearly translatable drive screw 612 of ball screw 610 is drivingly coupled to a linkage assembly 614. The linkage assembly 614 provides a mechanical advantage to axially translate lower spring seat 616 relative to a lower mount 618. As previously described, actuation of electric motor 602 in a first direction causes drive screw 612 to translate in a first axial direction. Opposite direction rotation of motor 602 causes drive screw 612 to translate in the opposite axial direction. A ride height of the vehicle may be adjusted through selective actuation of electric motor 602.

Claims

CLAIMSWhat is claimed is:1 . A leveling system for a vehicle including a sprung mass and an unsprung mass, the leveling system comprising: an electromechanical actuator including an electric motor; a gear reduction unit selectively driven by the electric motor; a rotary to linear motion conversion mechanism selectively driven by the electric motor and including a first rotatable member and a second axially translatable member, the first rotatable member being adapted to be coupled to one of the sprung and unsprung masses, wherein the linearly translatable member is adapted to be coupled to the other of the sprung and unsprung masses; and a clutch positioned to selectively supply and interrupt power transmission between the electric motor and the rotary to linear motion conversion mechanism wherein the clutch is operable in an open mode and a torque transferring mode, the electric motor being operable in either of the open mode or the torque transferring mode of the clutch, wherein a distance between the sprung mass and the unsprung mass is changed when the electric motor is operated and the clutch is torque transferring mode.

2. The leveling system of claim 1 , further comprising a damper arranged in parallel with the electromechanical actuator, the damper including a first end adapted to be coupled to one of the sprung and unsprung masses and a second end adapted to be coupled to the other of the sprung and unsprung masses.

3. The leveling system of claim 1 , further comprising a damper including a first end adapted to be coupled to one of the sprung and unsprung masses and a second end coupled to the electromechanical actuator.

4. The leveling system of claim 1 , wherein the electric motor directly drives the gear reduction unit and an output of the gear reduction unit drives the clutch.

5. The leveling system of claim 4, further comprising another gear reduction unit positioned between the clutch and the rotary to linear motion conversion mechanism.

6. The leveling system of claim 1 , wherein the clutch includes an input and an output, the electric motor being operable to drive the input of the clutch, the output of the clutch being operable to drive the gear reduction unit.

7. The leveling system of claim 1 , wherein the rotary to linear motion conversion mechanism includes a lead screw, a power screw or a rack and pinion.

8. The leveling system of claim 1 , further comprising a linkage assembly driven by the rotary to linear motion conversion mechanism.

9. The leveling system of claim 1 , wherein the rotary to linear motion conversion mechanism includes a helper spring urging the sprung mass away from the unsprung mass.

10. The leveling system of claim 1 , wherein the clutch is a magnetorheological clutch.1 1 . The leveling system of claim 1 , wherein the electromechanical actuator is positioned between one of an upper spring seat and an upper mount, and a lower spring seat and a lower mount.

12. A method of changing a ride height of a vehicle, comprising: positioning an electromechanical actuator between a sprung mass and an unsprung mass of a vehicle; the electromechanical actuator including an electric motor, a gear reduction unit selectively driven by the electric motor, a rotary to linear motion conversion mechanism selectively driven by the electric motor, and a clutch, the rotary to linear motion conversion mechanism including a rotatable member adapted to be coupled to one of the sprung and unsprung masses and a linearly translatable member adapted to be coupled to the other of the sprung and unsprung masses, the clutch being positioned to selectively supply and interrupt power transmission between the electric motor and the rotary to linear motion conversion mechanism; energizing the electric motor when the clutch is in an open mode; rotating the motor at a predetermined operating speed while the clutch is in the open mode; subsequently operating the clutch in a torque transferring mode; andchanging a distance between the sprung mass and the unsprung mass when the electric motor is energized and the clutch is in the torque transferring mode.

13. The method of claim 12, wherein the clutch is a magnetorheological clutch.

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