PATENT DOCUMENT

Publication Number: US-11701942-B2
Application Number: US-202217735145-A
Country: US
Kind Code: B2

Title: Motion control system

Abstract:
A motion control system includes a top mount, a bottom mount, a rigid housing, an air spring, and a linear actuator. The air spring transfers force of a first load path between the top mount and the bottom mount. The air spring includes a pressurized cavity containing pressurized gas that transfers the force of the first load path. The linear actuator transfers force of a second load path between the top mount and the bottom mount in parallel to the first load path. The rigid housing defines at least part of the pressurized cavity and transfers the force of the second load path.

Claims:
What is claimed is: 
     
       1. A suspension system comprising:
 a top mount; 
 a bottom mount; 
 a rigid housing; 
 an air spring including a pressurized cavity containing pressurized gas that transfers a force of a first load path between the top mount and the bottom mount; and 
 a linear actuator that transfers a force of a second load path between the top mount and the bottom mount in parallel to the first load path, 
 wherein the pressurized cavity includes an upper chamber and a lower chamber, and wherein the pressurized gas flows between the upper chamber and the lower chamber around the linear actuator. 
 
     
     
       2. The suspension system according to  claim 1 , wherein the linear actuator is contained in the pressurized cavity. 
     
     
       3. The suspension system according to  claim 1 , wherein the rigid housing includes a first rigid housing coupled to the top mount with an isolator that seals the pressurized cavity and transfers the force of the second load path between the first rigid housing and the top mount. 
     
     
       4. The suspension system according to  claim 3 , wherein the first rigid housing is a housing of the linear actuator and defines the upper chamber of the pressurized cavity. 
     
     
       5. The suspension system according to  claim 3 , wherein the rigid housing includes a second rigid housing coupled to the bottom mount with a flexible membrane that seals the pressurized cavity. 
     
     
       6. The suspension system according to  claim 5 , wherein the flexible membrane is connected to the first rigid housing and the second rigid housing to couple the rigid housing to the bottom mount, and the second rigid housing defines the lower chamber of the pressurized cavity. 
     
     
       7. The suspension system according to  claim 5 , wherein the pressurized cavity is defined by the top mount, the isolator, the first rigid housing, the second rigid housing, the flexible membrane, and the bottom mount. 
     
     
       8. The suspension system according to  claim 1 , wherein the linear actuator is a ball screw actuator having a ball nut, a shaft, and a ball spline that prevents rotation of the shaft relative to the rigid housing, wherein torque is selectively applied to the ball nut by a motor to apply the force of the second load path to the shaft. 
     
     
       9. The suspension system according to  claim 8 , wherein the rigid housing is coupled to the ball nut with a thrust bearing. 
     
     
       10. A suspension system comprising:
 a top mount; 
 a bottom mount; 
 a rigid housing; 
 an air spring that transfers a force of a first load path between the top mount and the bottom mount, the air spring including a pressurized cavity having an upper chamber and a lower chamber containing pressurized gas that transfer the force of the first load path; and 
 a ball-screw actuator having a ball nut and a shaft, the ball-screw actuator transferring a force of a second load path between the top mount and the bottom mount in parallel to the first load path, 
 wherein the rigid housing is spaced radially apart from and surrounds the ball-screw actuator to define a circumferential gap therebetween, wherein the pressurized gas flows between the upper chamber and the lower chamber through the circumferential gap. 
 
     
     
       11. The suspension system according to  claim 10 , wherein the ball-screw actuator includes a motor having a rotor and a stator that are contained in the pressurized cavity. 
     
     
       12. The suspension system according to  claim 11 , wherein the stator is in contact with an inner surface of the rigid housing. 
     
     
       13. The suspension system according to  claim 10 , wherein the rigid housing is a first rigid housing, and the suspension system further includes a second rigid housing that surrounds the first rigid housing, wherein the first rigid housing is coupled to the second rigid housing with an upper isolator and a lower isolator by which the force of the second load path is transferred between the first rigid housing and the second rigid housing. 
     
     
       14. The suspension system according to  claim 13 , wherein the first rigid housing is coupled to the top mount with an isolator to limit relative movement between the first rigid housing and the top mount. 
     
     
       15. The suspension system according to  claim 13 , wherein the first rigid housing includes a port by which the air spring receives pressurized gas. 
     
     
       16. A suspension system comprising:
 an air spring configured to form a first load path between a vehicle body of a vehicle and an unsprung component of the vehicle, the air spring including a pressurized cavity having an upper chamber and a lower chamber containing pressurized gas that transfer a force of the first load path; 
 a ball-screw actuator configured to form a second load path between the vehicle body and the unsprung component in parallel to the first load path, the ball-screw actuator comprising:
 a shaft; 
 a housing comprising an inner housing and an outer housing to which the inner housing is coupled; 
 a motor coupled to the inner housing and having a stator and a rotor; 
 a ball nut to which the motor applies torque to transfer a force of the second load path between the housing and the shaft; and 
 a ball spline coupled to the inner housing, 
 
 wherein the ball spline applies torque to the shaft to prevent rotation of the shaft relative to the outer housing and prevent a transfer of torque from the motor to the unsprung component, and 
 wherein pressurized gas communicates between the upper chamber and the lower chamber through the ball-screw actuator through axial channels in the inner housing. 
 
     
     
       17. The suspension system according to  claim 16 , wherein the housing, the stator, and the ball spline are coupled to each other to form a stationary assembly, and the rotor and the ball nut are coupled to each other to form a rotating assembly that is rotatably supported and axially fixed to the stationary assembly with a thrust bearing. 
     
     
       18. The suspension system according to  claim 16 , wherein the motor of the ball-screw actuator is contained in the pressurized cavity. 
     
     
       19. The suspension system according to  claim 16 , wherein the inner housing is coupled to the outer housing with a first isolator positioned above the stator and with a second isolator positioned below at least a portion of the stator. 
     
     
       20. The suspension system according to  claim 16 , wherein the outer housing surrounds the inner housing, the motor, and the ball nut and the outer housing transfers the force of the first load path and the force of the second load path between the unsprung component and the vehicle body.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is continuation of U.S. application Ser. No. 16/611,612, filed Nov. 7, 2019, which is a national stage application of International Application No. PCT/US2018/029753, filed Apr. 27, 2018, which claims priority to and the benefit of U.S. Provisional Application No. 62/503,093, filed May 8, 2017, the entire disclosures of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to motion control system. 
     BACKGROUND 
     Motion control systems control transmission of forces between a sprung mass and an unsprung mass. Traditional motion control systems are passive systems that include a spring-damper system of which the spring and the damper have fixed characteristics. Such fixed characteristics, however, may not be suited for user comfort given varying surface conditions and varying user preferences. Newer motion control systems are active systems of which various characteristics may be controlled by the user (e.g., an operator) or automatically in response to various detected conditions. For example, motion control systems may utilize an air spring to allow the user to select a desired height of the sprung mass. Magnetorheological dampers provide damping characteristics that may vary according to detected conditions, such as acceleration. 
     SUMMARY 
     In one aspect, a suspension system includes a top mount, a bottom mount, a rigid housing, an air spring, and a linear actuator. The air spring transfers force of a first load path between the top mount and the bottom mount. The air spring includes a pressurized cavity containing pressurized gas that transfers the force of the first load path. The linear actuator transfers force of a second load path between the top mount and the bottom mount in parallel to the first load path. The rigid housing defines at least part of the pressurized cavity and transfers the force of the second load path. 
     The rigid housing may be coupled to the top mount with an isolator that seals the pressurized cavity and transfers the force of the second load path between the rigid housing and the top mount. 
     The linear actuator and the rigid housing may form a first piston assembly of the air spring movable relative to the bottom mount, while the top mount may form a second piston assembly of the air spring movable relative to the bottom mount. Effective piston areas of the first piston assembly and the second piston assembly may be approximately equal. 
     The rigid housing may be coupled to the bottom mount with a flexible membrane that seals the pressurized cavity and permits the first piston assembly to move relative to the bottom mount, and the isolator permits the second piston assembly to move relative to the rigid housing. The pressurized cavity may be defined by the top mount, the isolator, the rigid housing, the flexible membrane, and the bottom mount. 
     The suspension system may further include a second rigid housing coupled to the bottom mount, wherein the flexible membrane is connected to the rigid housing and the second rigid housing to couple the rigid housing to the bottom mount, and the second rigid housing defines a lower chamber of the pressurized cavity. 
     The linear actuator may include a motor having a rotor and a stator that are contained in the pressurized cavity. 
     The stator may be in contact with an inner surface of the rigid housing. 
     The rigid housing may be a first rigid housing, while the suspension system further includes a second rigid housing that surrounds the first rigid housing, and the first rigid housing is coupled to the second rigid housing with an upper isolator and a lower isolator by which the force of the second load path is transferred therebetween. 
     Alternatively, the rigid housing may be a first rigid housing, while the suspension system further includes a second rigid housing surrounded by the first rigid housing, and the second rigid housing is coupled to the linear actuator and the first rigid housing to transfer the force of the second load path therebetween. 
     The pressurized cavity may include an upper chamber and a lower chamber, wherein the pressurized gas flows between the upper chamber and the lower chamber is at least one of around or through the linear actuator. 
     The rigid housing may be spaced radially apart from and surround the linear actuator to define a circumferential gap therebetween, while the pressurized gas flows between the upper chamber and the lower chamber through the circumferential gap. Instead or additionally, the pressurized gas flows between the upper chamber and the lower chamber through an inner housing of the linear actuator. 
     The linear actuator may be a ball screw actuator having a ball nut and a shaft, and torque is selectively applied to the ball nut by a motor to apply the force of the second load path to the shaft. 
     The linear actuator may include a ball spline that prevents rotation of the shaft relative to the rigid housing. 
     A vehicle may include a vehicle body, one or more unsprung components, and one or more of the suspension systems, the top mount of each of the suspension system being coupled to the vehicle body and the bottom mount of each suspension system being coupled to one of the unsprung components. 
     The vehicle may include a pressurized air source in fluidic communication with the one or more suspension systems for supplying the pressurized gas to the pressurized cavities thereof, and a control system for controlling the linear actuators of the one or more suspension systems in response to dynamic loading between the vehicle body and the unsprung component coupled thereto. 
     The vehicle may include four of the unsprung components and four of the suspension systems. 
     A suspension system includes a spring and a ball-screw actuator. The spring is configured to form a first load path between a vehicle body of a vehicle and an unsprung component of the vehicle. The ball-screw actuator is configured to form a second load path between the vehicle body and the unsprung component in parallel to the first load path. The ball-screw actuator includes a shaft, a housing, a motor, a ball nut, and a ball spline. The motor is coupled to the housing and includes a stator and a rotor. The motor applies torque to the ball nut to transfer force of the second load path between the housing and the shaft. The ball spline applies torque to the shaft to prevent rotation thereof relative to the housing. The housing, the stator, and the ball spline are coupled to each other to form a stationary assembly. The rotor and the ball nut are coupled to each other to form a rotating assembly that is rotatably supported and axially fixed to the stationary assembly with a thrust bearing. 
     The thrust bearing may be coupled to the ball nut and the housing. The rotating assembly may be further rotatably supported by the housing with another bearing coupled to the housing and the rotor. The other bearing may be spaced apart from and positioned axially above the thrust bearing. The stator may be positioned axially between the thrust bearing and the other bearing. The spring may be one of a coil spring or an air spring. The housing may be an inner housing, while the suspension system further includes an outer housing to which the inner housing is coupled and which surrounds the inner housing, the motor, and the ball nut. The inner housing may be coupled to the outer housing with a first tube isolator positioned above the stator. The inner housing may be coupled to the outer housing with a second tube isolator positioned below at least a portion of the stator. 
     A ball screw actuator includes a housing, a motor, a shaft, a ball nut, and a ball spline. The motor is position in the housing. The housing surrounds the motor and includes cooling passages for receiving a fluid for cooling the motor. The shaft moves axially within the housing. The motor applies torque to the ball nut for transferring axial force between the housing and the shaft. The ball spline transfers torque between the housing and the shaft to prevent rotation therebetween. The housing is coupled to the ball nut to allow rotation therebetween and prevent axial movement therebetween. The housing is coupled to the ball spline to prevent rotation and axial movement therebetween. 
     The housing may be coupled to the ball nut with a thrust bearing. A rotor of the motor may be rotatably coupled to the housing with another bearing positioned above the thrust bearing. The housing may extend from above the motor to below the ball nut. The ball spline may be positioned below the ball nut and be coupled to a lower end of the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. 
         FIG.  1    is a schematic view of a vehicle according to an exemplary embodiment. 
         FIG.  2    is another schematic view of the vehicle of  FIG.  1   . 
         FIG.  3    is a cross-sectional schematic view a suspension system of the vehicle of  FIG.  1   . 
         FIG.  4    is a cross-sectional schematic view of a variant of the suspension system of  FIG.  3   . 
         FIG.  5    is a schematic view of a controller. 
         FIG.  6 A  is an elevation schematic view of a suspension system for use with the vehicle of  FIG.  1   . 
         FIG.  6 B  is a cross-sectional view of the suspension system of  FIG.  6 A . 
         FIG.  6 C  is a cross-sectional view of an actuator of the suspension system of  FIG.  6 A . 
         FIG.  6 D  is a cross-sectional view of a rotating structure of the suspension system of  FIG.  6 A . 
         FIG.  6 E  is a cross-sectional view of a stationary structure of the suspension system of  FIG.  6 A . 
         FIG.  6 F  is a schematic view of a vehicle comprising four of the suspension systems of  FIG.  6 A . 
         FIG.  7 A  is a cross-sectional schematic view of another suspension system for use in the vehicle of  FIG.  1   . 
         FIG.  7 B  is a cross-sectional schematic view of the suspension system of  FIG.  7 A  with a pressurized cavity indicated in cross-hatching. 
         FIG.  7 C  is a schematic view of a vehicle comprising four of the suspension systems of  FIG.  7 A  and a pressurized air source. 
         FIG.  8 A  is a cross-sectional schematic view of another suspension system for use in the vehicle of  FIG.  1   . 
         FIG.  8 B  is a cross-sectional schematic view of the suspension system of  FIG.  8 A  with a pressurized cavity indicated in cross-hatching. 
         FIG.  9    is a cross-sectional schematic view of a variation of the suspension system of  FIG.  8 A  with a pressurized cavity indicated in cross-hatching. 
         FIG.  10    is a cross-sectional schematic view of another variation of the suspension system of  FIG.  8 A  with a pressurized cavity indicated in cross-hatching. 
         FIG.  11 A  is a cross-sectional schematic view of another suspension system for use in the vehicle of  FIG.  1   . 
         FIG.  11 B  is a cross-sectional schematic view of the suspension system of  FIG.  11 A  with a pressurized cavity indicated in cross-hatching. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein are various embodiments of a vehicle  100  and functional subsystems thereof, including a suspension system  160 . More particularly, the suspension system  160  is an active suspension system, which is configured to control generally vertical motion of the wheels with a linear actuator that can apply upward and downward force to introduce energy into and absorb energy from the wheels. 
     Referring to  FIG.  1   , the vehicle  100  generally includes a vehicle body  102  and a drive system  120  connected to the vehicle body  102 . The vehicle body  102  may, for example, include or define a passenger compartment for carrying passengers. The drive system  120  is configured to move the vehicle  100 , including the passenger compartment. The drive system  120  includes various functional subsystems, including a propulsion system  130  (i.e., for propelling the vehicle  100 ), a braking system  140  (i.e., for slowing the vehicle  100 ), a steering system  150  (i.e., for directing the vehicle  100  in different directions), a suspension system  160  (i.e., for supporting the vehicle  100 ), a sensing system  170  (i.e., for sensing various aspects of the vehicle  100 , including the various subsystems and the external environment), and a control system  180  (i.e., for controlling the various other subsystems individually or in a coordinated manner). The drive system  120  may be an autonomous drive system that operates the various functional subsystems to move the vehicle  100  to a user-selected location without further input from the user. 
     Referring to  FIG.  2   , the vehicle  100  includes wheels  104  (e.g., four) that are coupled to and support the vehicle body  102  (e.g., on a public roadway). The wheels  104  may be coupled to the vehicle body  102 , for example, with the propulsion system  130 , the steering system  150 , and the suspension system  160 . The wheels  104  may include tires (not separately shown or labeled), such that each wheel  104  may be considered a subassembly of a wheel rim and a tire. 
     The propulsion system  130  generally includes one or more motors  232 , one or more gearboxes  234 , and drive shafts  236  (e.g., half-shafts) operatively connecting each wheel  104  to one of the gearboxes  234 . Broadly speaking, the motors  232  provide torque to the gearboxes  234 , the gearboxes  234  alter the output torque (e.g., increase) and output speed (e.g., decrease) of the motors  232 , and the drive shafts  236  transfer torque from the gearboxes  234  to the wheels  104 . The motors  232  may provide positive torque for propelling the vehicle  100  in a forward direction and for decelerating the vehicle  100  when moving in a rearward direction, and may provide negative torque for propelling the vehicle  100  in a rearward direction and for deceleration the vehicle  100  when moving in a forward direction. The motors  232  may also function as generator, when receiving torque from the wheels  104 , and function to recharge a battery (not shown) or other energy storage system of the vehicle  100 . As shown, the propulsion system  130  may include a front propulsion system  130   f  and a rear propulsion system  130   r  that each include two motors  232  coupled to a single gearbox  234  and associated with one drive shaft  236  and the one wheel  104  coupled thereto. Variations of the propulsion system  130  are contemplated, which may include a different number of driven wheels  104  (e.g., only front or rear wheels being driven), a different number of motors  232  associated with the wheels  104  (e.g., one motor  232  associated with two wheels  104 ), and a different number of gearboxes  234  associated with the wheels  104  (e.g., one gearbox  234  dedicated for each wheel  104 ). 
     The braking system  140  generally provides deceleration torque via friction for decelerating the vehicle  100  when moving in the forward direction and/or when moving in the rearward direction. 
     The steering system  150  generally includes one or more steering actuators  252  and steering linkages  254  operatively coupling each wheel  104  to one of the steering actuators  252 . Broadly speaking, the steering system  150  controls the pivoted position of the wheels  104  about generally vertical axes. The steering actuators  252  move the steering linkages  254  in inboard and outboard directions relative to the vehicle body  102  to, thereby, pivot the wheels  104  about the vertical axes. As shown, the steering system  150  may include a front steering system  150   f  and a rear steering system  150   r  that each include one steering actuator  252  that is associated with two steering linkages  254  and the wheels  104  coupled thereto. Variations of the steering system  150  are contemplated, which may include a different number of steering actuators  252  associated with the wheels  104  (e.g., one steering actuator  252  for each wheel  104 ). 
     The suspension system  160  generally includes an actuator  262  (e.g., suspension actuator) and a shaft  264  (e.g., suspension shaft) associated with each wheel  104 . Mechanical components, including the actuator  262 , the shaft  264 , and other components discussed below, of the suspension system  160  may be considered an assembly (e.g., suspension assembly). Broadly speaking, the suspension system  160  controls vertical motion of the wheels  104  relative to the vehicle body  102 , for example, to ensure contact between the wheels  104  and a surface of the roadway and to limit the influence of roadway conditions on undesirable movements of the vehicle body  102 . The suspension system  160  is an active suspension system in which the actuators  262  transfer energy into and absorb energy from the wheels  104  with upward and downward movement relative to the vehicle body  102 . As shown, the suspension system  160  may include a front left suspension system  160   fl , a front right suspension system  160   fr , a rear left suspension system  160   rl , and a rear right suspension system  160   rr , each of which include one actuator  262  and one shaft  264 . Further details of the suspension system  160  are discussed in further detail below. 
     The sensing system  170  includes sensors for observing external conditions of the vehicle  100  (e.g., location of the roadway and other objects) and conditions of the vehicle  100  (e.g., acceleration and conditions of the various subsystems and their components). The sensing system  170  may include sensors of various types, including dedicated sensors and/or functional components of the various subsystems (e.g., actuators may function as sensors). 
     The control system  180  includes communication systems and components (i.e., for receiving sensor signals and sending control signals) and processing components (i.e., for processing the sensor signals and determining control operations), such as a controller. The control system  180  may include various control subsystems, for example, associated with (or as part) of one or more of the various other subsystems described herein (e.g., the propulsion system  130 , the braking system  140 , etc.). 
     Referring to  FIG.  5   , a hardware configuration for a controller  581  of the control system  180  is shown, which may be used to implement the apparatuses and systems described herein (e.g., to detect an impact upon occurrence thereof and/or predict an impact in expectation thereof, and to control the movement mechanisms). As an example, the controller  581  may output a command, such as a voltage value, to the various subsystems of the drive system  120  in response to signals received from the sensors of the sensing system  170 . 
     The controller  581  may include a processor  581   a , a memory  581   b , a storage device  581   c , one or more input devices  581   d , and one or more output devices  581   e . The controller  581  may include a bus  581   f  or a similar device to interconnect the components for communication. The processor  581   a  is operable to execute computer program instructions and perform operations described by the computer program instructions. As an example, the processor  581   a  may be a conventional device such as a central processing unit. The memory  581   b  may be a volatile, high-speed, short-term information storage device such as a random-access memory module. The storage device  581   c  may be a non-volatile information storage device such as a hard drive or a solid-state drive. The input devices  581   d  may include any type of human-machine interface such as buttons, switches, a keyboard, a mouse, a touchscreen input device, a gestural input device, an audio input device, the sensors of the sensing system  170 . The output devices  581   e  may include any type of device operable to provide an indication to a user regarding an operating state, such as a display screen or an audio output, or any other functional output or control, such as the propulsion system  130 , the braking system  140 , the steering system  150 , and/or the suspension system  160 . 
     Referring to  FIG.  3   , the suspension system  160  is configured as a strut assembly that is coupled at an upper end thereof to the vehicle body  102  and at a lower end thereof to an unsprung component  306  that supports the wheel  104 . The unsprung component  306  moves upward and downward relative to the vehicle body  102  and may, for example, be a steering knuckle or a suspension control arm. 
     The suspension system  160  generally includes the actuator  262  and the shaft  264 , along with a spring  366 , which cooperatively function to transfer force axially between the unsprung component  306  and the vehicle body  102  through two load paths (e.g., dual paths). The spring  366  may be a coil spring (e.g., metal coil spring), or may be another suitable type of spring for use in the present suspension system  160  (e.g., an air spring, spring formed of another solid material, such as a composite). The first load path is formed by the spring  366  and carries a gravity preload of the vehicle  100  (i.e., load due to gravity irrespective of any dynamic loading) along with a portion of a dynamic load between the vehicle body  102  and the unsprung component  306 . The second load path is formed by the actuator  262  and the shaft  264 , which carries another portion of the dynamic load between the vehicle body and the unsprung component  306  and, as compared to the first load path, provides primary damping functions of the suspension system  160 . 
     The suspension system  160  further includes a housing  368 , a top mount  370 , and a bottom mount  372 , along with vibration isolators (e.g., dampers, bushings, etc.) and one or more load sensors  380 . The housing  368  is coupled to both the actuator  262  and the spring  366  to transfer the second load path and the first load path, respectively, to and from the top mount  370  (i.e., to the vehicle body  102 ) and the bottom mount  372  (i.e., to the unsprung component  306 ). The actuator  262  is generally contained within the housing  368  and is coupled thereto with an upper inner isolator  374  (e.g., first vibration isolator, or upper actuator isolator) and a lower inner isolator  376  (e.g., second vibration isolator, or lower actuator isolator) that transfer axial, radial, and torsional forces there between. The spring  366  is coupled to a lower end of the housing  368  and includes an outer isolator  378  (e.g., third vibration isolator, lower isolator, or coil spring isolator) that transfers axial force there between. 
     Because the preload (i.e., vehicle weight) is applied to the suspension system  160  via the first load path through the spring  366  and bypasses the actuator  262 , the second load path is nominal (e.g., near zero) in static or near static conditions, thereby allowing the upper inner isolator  374  and the lower inner isolator  376  to be significantly less stiff than the outer isolator  378 . For example, the upper inner isolator  374  and the lower inner isolator  376 , by not transferring the preload, may be configured with spring rate curves, damping coefficients, and other characteristics independent of the corresponding characteristics of the outer isolator  378 . Moreover, upper inner isolator  374  and the lower inner isolator  376  may have different such characteristics than each other. 
     The top mount  370  is coupled to an upper end of the housing  368  and the vehicle body  102  to transfer forces to the vehicle body  102  (i.e., the first and second load paths). The bottom mount  372  is separately coupled to lower ends of the spring  366  and the shaft  264 , respectively, to transfer force to the unsprung component  306  (i.e., the first and second load paths). 
     The actuator  262  is arranged above the spring  366 , so as to be supported (e.g., suspended) from thereabove by the vehicle body  102 . This orientation may provide several advantages as compared to mounting the actuator  262  below the spring  366  (i.e., as compared to supporting the actuator  262  with the unsprung component  306  from therebelow). For example, the actuator  262 , by being supported by the vehicle body  102 , is not unsprung mass, and also the actuator  262  is mounted closer to the vehicle body  102  for connection to power, data, and/or cooling lines at locations nearer the vehicle body  102  and less susceptible to damage (e.g., being impacted by debris). 
     The actuator  262  is a ball screw actuator, which converts rotational motion and torque from an electric motor (not labeled), respectively, into linear motion and force of the shaft  264 . A torque output of the motor generally correlates to a linear force output of the actuator  262 . Specific details of ball screw aspects of the actuator  262  are not discussed herein. 
     The actuator  262  functions to transfer energy to the wheel  104  to cause upward and downward motion of the wheel  104  relative to the vehicle body  102 . The actuator  262  also functions to absorb energy from the wheel  104  (e.g., functioning as a damper), as the wheel  104  is moved upward and downward relative to the vehicle body  102  from external forces (i.e., external to the actuator  262 ). Upward movement from external forces is caused by a roadway applying an upward force to the wheel  104  as the vehicle  100  moves therealong. Downward movement from external forces is generally caused by gravity acting on the wheel  104  and/or the spring  366  applying a downward force to the wheel  104 . 
     The actuator  262  includes a primary body  262   a  relative to which the shaft  264  is moved axially. The primary body  262   a  may, for example, form or contain a motor (e.g., forming a stator and containing a rotor of the motor) at an upper end thereof and a rotating nut (e.g., a ball nut) at a lower end thereof. As the nut is rotated by the motor, the nut engages the shaft  264  (via recirculating balls) and causes the shaft  264  to translate axially relative to the primary body  262   a.    
     The primary body  262   a  is mounted within the housing  368  with the upper inner isolator  374  and the lower inner isolator  376 , so as to transfer axial, radial, and rotational forces therebetween. The upper inner isolator  374  and the lower inner isolator  376  are configured to dampen and prevent noise and vibrations of the actuator  262  (e.g., from operating the motor and balls moving in a nut of the ball screw mechanism) from reaching the vehicle body  102 , while also allowing the actuator  262  to move axially and radially relative to the housing  368 . 
     Each of the upper inner isolator  374  and the lower inner isolator  376  are axially coupled, directly or indirectly, to inner and outer surfaces, respectively, of the housing  368  and the primary body  262   a  of the actuator  262  to transfer axial forces therebetween (i.e., the second load path). The upper inner isolator  374  and the lower inner isolator  376  are also arranged radially (e.g., concentrically) between the housing  368  and the primary body  262   a  to transfer radial forces therebetween (e.g., due to bending moments). The upper inner isolator  374  and the lower inner isolator  376  may also be rotationally coupled, directly or indirectly, to the housing  368  and the primary body  262   a  of the actuator to transfer rotational torque therebetween. The upper inner isolator  374  and the lower inner isolator  376  may, for example, be made of a suitable material (e.g., rubber or polymer) having suitable properties (e.g., damping characteristics and spring rate) due to material properties and/or structural characteristics thereof. 
     In the axial direction, the upper inner isolator  374  and the lower inner isolator  376  are configured to progressively deflect axially over a stroke (e.g., stroke distance) as axial force increases to a maximum design load. The maximum design load may be a peak (or near peak) load expected during operation of the vehicle  100  (e.g., an extreme condition during normal driving after which the suspension system  160  may be expected to continue operating). The maximum design load may, for example, be 10 kN, while a maximum design deflection (e.g., maximum stroke) may be 10 mm. A restorative spring force of the upper inner isolator  374  and the lower inner isolator  376  are preferably substantially linear over the stroke, for example, with the upper inner isolator  374  and the lower inner isolator  376  cooperatively providing an axial spring rate that is substantially constant (e.g., +/−25%, +/−˜15%, +/−10% or less) over the stroke, such as approximately 1 kn/mm. A substantially constant spring rate may be particularly advantageous for control strategies of the suspension system  160  (e.g., simplifying control strategies). 
     Alternatively, the restorative spring force may be substantially linear over a majority of the stroke. The spring rate may substantially constant over the first portion of the stroke (e.g., between approximately 75% and 90% of the stroke) and increase gradually over a second portion of the stroke (e.g., between 10% and 25% of the remaining stroke) to a markedly higher spring rate. This markedly higher spring rate in a second portion of the stroke may prevent harsh engagement between two generally rigid components of the suspension system  160  upon experiencing higher loading (e.g., near 10 kN). 
     In the radial direction, the upper inner isolator  374  and the lower inner isolator  376  are configured to prevent radial engagement of the actuator  262  (e.g., the primary body  262   a ) with the housing  368 . In the radial direction, the upper inner isolator and the lower inner isolator  376  may be significantly less stiff than in the radial direction. Radial engagement between the actuator  262  and the housing  368  might otherwise occur as a bending moment is applied to the suspension system  160 . Such a bending moment may, for example, arise from deflection of the unsprung component  306  relative to the vehicle body  102 . To this end, the upper inner isolator  374  and the lower inner isolator  376  are, respectively, coupled to the primary body  262   a  at axially spaced apart locations, which reduces the radial force components of the bending moment experienced by each of the upper inner isolator  374  and the lower inner isolator  376  as the actuator  262  pivots about the other of the upper inner isolator  374  and the lower inner isolator  376 . Larger axial spacing may allow the upper inner isolator  374  and the lower inner isolator  376  to be less stiff in the radial direction (i.e., having a lower restorative spring rate) and/or the housing  368  to be in closer proximity (e.g., being smaller) to the primary body  262   a.    
     The top mount  370  permits the suspension system  160  to pivot relative to the vehicle body  102  with little resistance (e.g., freely or with low resistance) to prevent high bending moments from being applied to the actuator  262  from movement of the unsprung component  306 . More particularly, the top mount  370  permits the suspension system  160  to pivot with little resistance (e.g., freely or with low resistance) in two rotational degrees of freedom (e.g., free or unrestricted degrees of freedom) about axes perpendicular to a longitudinal axis of the shaft  264 . By providing little (e.g., low) resistance to pivoting in the two unrestricted degrees of freedom, the coupling between the suspension system  160  and the vehicle body  102  contributes little to the bending moment otherwise acting the suspension system  160 . The top mount  370  may, as shown, be a cardan joint. Alternatively, the top mount  370  may be a ball-and-socket joint having an interference feature (e.g., protrusion in a slot), or be an isolator. As a result of the two free degrees of freedom, the suspension system  160  may pivot relative to the vehicle body  102  in a generally conical region, the peak of which is located generally at the top mount  370 . 
     The top mount  370  may also restrict (e.g., preventing or with high resistance) pivoting in a third rotational degree of freedom (e.g., restricted degree of freedom) about the longitudinal axis (top-to-bottom across the page as shown). By providing high resistance (e.g., preventing movement) in the restricted degree of freedom, the suspension system is prevented from rotating as the actuator  262  is operated (e.g., when the motor is rotated). 
     As shown schematically in  FIG.  4   , the suspension system  160  may additionally include a torsional isolator  482  (e.g., arranged between the housing  368  and the top mount  370 , which dampens rotational loads not otherwise dampened by the other isolators (discussed in further detail below), for example, caused by rotation of the motor of the actuator  262 . 
     As referenced above, the outer isolator  378  is arranged axially between the spring  366  and the housing  368  to transfer axial forces of the first load path therebetween. The preload (i.e., due to gravity acting on the vehicle) is transferred through the outer isolator, which as a result is configured to be substantially more stiff (e.g., has a higher restorative spring rate) in the axial direction than the upper inner isolator  374  and the lower inner isolator  376 . 
     The suspension system  160  may additionally include one or more load sensors  380 , which are configured to measure axial loading of the suspension system  160  to the vehicle body  102 . The one or more load sensors  380  are, for example, arranged axially between the top mount  370  and the housing  368 . The load sensors  380  may also be considered part of the sensing system  170  and be in communication with control system  180 . 
     The control system  180 , or a suspension control subsystem thereof, controls the actuator  262  to achieve desired force transfer between the wheel  104  and the vehicle body  102 . As referenced above, the actuator  262  is configured to absorb external energy acting on the wheel  104  to, thereby, function as a damper as the wheel  104  moves both up and down relative to the vehicle body  102 . Absorbing refers to taking energy out of the suspension system  160 , for example, by converting and storing the mechanical energy as electrical energy (e.g., with the motor of the actuator  262  as a motor-generator). The actuator  262  is also configured to input energy to the wheel  104  to, thereby, cause the wheel  104  to move up and down relative to the vehicle body  102 . 
     The control system  180  may, when operating the actuator  262  to achieve a desired axial force transfer between the vehicle body  102  and the wheel  104 , adjust an input of the actuator  262  to account for axial compliance introduced by the upper inner isolator  374 , the lower inner isolator  376 , and, to a lesser extent, the outer isolator  378 . For example, compressive states of the upper inner isolator  374 , the lower inner isolator  376 , and the outer isolator  378  may be accounted for using the load sensors  380  (e.g., based on known or tested spring rates). Based on different measurements by the load sensors  380  received at different times, the input to the actuator  262  (e.g., rotational speed and/or torque of the motor) may be different despite seeking the same output and response from the actuator  262  (i.e., axial force and/or displacement in a given timeframe). For example, assuming a cooperative spring rate of 1 kN/mm of the isolators and a preload of 5 kN (i.e., the first load path), an axial force measurement of 5 kN would represent a 0 kN axial load (i.e., via the second load path) and 0 mm of deflection of the isolators. Thus, to achieve a desired output force of 8 kN in the given time frame, 3 mm of compliance must be accounted for, for example, by initially rotating the motor at a relatively high rate of speed. An axial force measurement of 7 kN would represent a 2 kN axial load and 2 mm of deflection of the isolators. Thus, to achieve the same desired output force of 8 kN in the same given timeframe, 1 mm of compliance must be accounted for, for example, by initially rotating the motor at a relatively low rate of speed. 
     The suspension system  160  may additionally include position sensors  384  (e.g., displacement sensors), which measure deflection of the various isolators (e.g., by measure a change in position of the primary body  262   a  of the actuator  262  relative to the housing  368 . This displacement information may be used, alone and/or in conjunction with the force information, to determine inputs to the actuator  262  (e.g., rotational speed and/or torque of the motor). For example, material properties of the various isolators may change with temperature and/or aging, which may be accounted for by measuring displacement of the isolators with the position sensors  384 . For example, a measured displacement that does not correlate to an expected force value may be accounted for with the inputs to the actuator  262  to achieve a desired axial force or displacement output (e.g., using the example above, a 2 mm measured displacement would not correlate to a 6 kN measured force). 
     Referring to  FIGS.  6 A- 6 B , a suspension system  660  may be used as any of the suspension systems  160   fl ,  160   fr ,  160   rl ,  160   rr  shown in  FIG.  1   . The suspension system  660  is coupled at an upper end thereof to the vehicle body  102  and at a lower end thereof to the unsprung component  306 . The suspension system  660  is configured similar to the suspension system  160  described previously. Where common reference numerals are used between the suspension system  660  and the suspension system  160  to identify components, features, or other elements of the suspension system  660 , the discussion of the suspension system  160  may be referred to for further details of such components, features, or other elements. The suspension system  660  and the variations described below (e.g., suspensions systems  760 ,  860 ,  960 ,  1060 , and  1160 ) may also be referred to as suspension assemblies or devices, or strut systems, assemblies, or devices. 
     The suspension system  660  generally includes an actuator  662 , a shaft  664 , the spring  366 , and an outer housing  668 , which may be used as the actuator  262 , the shaft  264 , the spring  366 , and the housing  368 , respectively, in the suspension system  160 . The suspension system additionally includes the top mount  370  and the bottom mount  372 . 
     As discussed above with reference to the suspension system  160 , the suspension system  660  is configured to transfer force axially from the unsprung component  306  to the vehicle body  102  via two parallel load paths. The first load path is formed by the spring  366  and the outer housing  668 , which carries the preload (e.g., a portion of the weight of the vehicle  100 ) and a portion of the dynamic load between the vehicle body  102  and the unsprung component  306 . The second load path is formed by the actuator  662 , the shaft  664 , and the outer housing  668 , which carry another portion of the dynamic load between the vehicle body  102  and the unsprung component  306 , including providing primary damping functions for road disturbances. 
     Referring also to  FIG.  6 C , the actuator  662  is a linear actuator, which is configured as a ball-screw actuator or mechanism. The actuator  662  includes a motor  662   a  having a rotor  662   b  and a stator  662   c , a ball nut  662   d  (e.g., a ball screw nut), a ball spline  662   e  (e.g., a ball spline nut), and an inner housing  662   f  having a lower inner housing portion  662   g  and an upper inner housing portion  662   h . The shaft  664  extends through the actuator  662  and may be considered a part of the actuator  662 . Broadly speaking, the motor  662   a  applies torque to the ball nut  662   d  relative to the outer housing  668  to control axial motion of the shaft  664  relative to the outer housing  668  and, thereby, control axial motion of the unsprung component  306  relative to the vehicle body  102 . The ball spline  662   e  prevents rotation of the shaft  664  relative to the outer housing  668  to prevent transfer of torque from the motor  662   a  via the shaft  664  to the unsprung component  306  (e.g., a suspension arm) or other components (e.g., the steering linkage  254 ). The actuator  662  and the other actuators described herein may be configured as other types of linear actuators, such as a rack-and-pinion system, linear motor, or other suitable linear actuator. The inner housing  662   f  and the outer housing  668  may also be referred to as rigid housings. The lower inner housing portion  662   g  and the upper inner housing portion  662   h  may also be referred to as a lower housing structure and an upper housing structure, respectively. 
     Referring additionally to  FIG.  6 D , the rotor  662   b  and the ball nut  662   d  rotate in unison. The rotor  662   b  and the ball nut  662   d  may be considered to cooperatively form a rotating structure  662 ′ of the actuator  662 . The ball nut  662   d  and the rotor  662   b  may be coupled to each other at axial ends thereof. For example, the ball nut  662   d  and the rotor  662   b  may be coupled to each other with threaded fasteners (not shown) that extend axially through a radially-extending flange of the ball nut  662   d  into the axial end of the rotor  662   b , such that torque generated by the motor  662   a  is transferred to the ball nut  662   d . The rotor  662   b  and the ball nut  662   d  may be coupled to each other manners to transfer torque therebetween, for example, with a male-to-female interference fit therebetween. The rotor  662   b  may, for example, include magnets  662   b ′ mounted to an outer radial surface of a spindle  662   b ″ that is configured as a hollow shaft. The rotor  662   b  is hollow, so as to surround and rotate independent of the shaft  664 , which translates axially therein. The rotating structure  662 ′ may also be referred to as a rotating assembly. 
     Referring additionally to  FIG.  6 E , the stator  662   c , the ball spline  662   e , and the inner housing  662   f  are coupled to each other in a fixed manner to prevent rotational and axial movement therebetween. The stator  662   c , the ball spline  662   e , and the inner housing  662   f  may be considered to cooperatively form a stationary structure  662 ″ of the actuator  662  relative to which the rotating structure  662 ′ rotates. The lower inner housing portion  662   g  and the upper inner housing portion  662   h  of the inner housing  662   f  are rigid annular structures that are coupled to each other at axial ends thereof to prevent relative movement therebetween. For example, the lower inner housing portion  662   g  and the upper inner housing portion  662   h  may be coupled to each other with threaded fasteners (not shown) extending axially therein, or in another suitable manner (e.g., a male-to-female interference fit). Alternatively, the inner housing  662   f  may be a unitary structure that forms the inner housing, or may be formed of additional structures that form the inner housing  662   f  The stator  662   c  is coupled inside the inner housing  662   f  to prevent relative movement therebetween, for example, being coupled to an inner surface of the upper inner housing portion  662   h  (e.g., being in contact therewith). As shown, the upper inner housing portion  662   h  may include cooling channels  662   f ′ (e.g., cooling passages) through which a fluid may flow so as to cool the motor  662   a  (e.g., the stator  662   c ). The upper inner housing portion  662   h  may also be referred to as a stator housing or cooling jacket. The stationary structure  662 ″ may also be referred to as a stationary assembly. 
     The ball spline  662   e  is coupled to the inner housing  662   f  to prevent relative rotational and axial movement therebetween, for example, being coupled to the lower inner housing portion  662   g . As shown, the ball spline  662   e  and the lower inner housing portion  662   g  each include radially extending flanges that overlap each other radially. The flanges of the ball spline  662   e  and the lower inner housing portion  662   g  are coupled to each other, for example, with threaded fasteners (not shown) extending axially therein and which prevent axial and rotational movement therebetween. The ball spline  662   e  and the lower inner housing portion  662   g  may be coupled to each other in other manners to prevent axial and/or rotational movement relative to each other, such as with a male-to-female interference fit to prevent relative rotation and a snap ring or nut to prevent axial movement). 
     The rotating structure  662 ′ (i.e., formed by the rotor  662   b  and the ball nut  662   d ) is configured to rotate relative to the stationary structure  662 ″ (i.e., formed by the stator  662   c , the ball spline  662   e , the lower inner housing portion  662   g , and the upper inner housing portion  662   h ), so as to apply axial force (i.e., the force of the second load path) between the stationary structure and the shaft  664 . The axial force applied by the rotating structure  662 ′ to the shaft  664  is to cause, restrict, prevent, or otherwise control axial movement of the shaft  664  relative to the actuator  662  to control force transmission in the second load path between the unsprung component  306  and the vehicle body  102 . 
     More particularly, the motor  662   a  receives electrical current, which generates torque between the rotor  662   b  and the stator  662   c . As torque is applied to the rotor  662   b , torque is applied to the ball nut  662   d , and axial force is applied from the ball nut  662   d  to the shaft  664 . More particularly, the axial force is applied between the ball nut  662   d  and the shaft  664  via a first set of recirculating balls (not shown; such as ball bearings), as are known in the art of ball screw nuts. The recirculating balls engage an outer helical groove  664   a  in an outer surface of the shaft  664  and an inner helical groove  662   d ′ corresponding thereto in an inner surface of the ball nut  662   d , so as to apply the axial force between the ball nut  662   d  and the shaft  664  as torque is applied to the ball nut  662   d . By controlling the torque applied by the motor  662   a  to the ball nut  662   d  (e.g., by controlling electrical power to the motor  662   a ), the axial force applied to the shaft  664  by the actuator  662  may be controlled, so as to cause, restrict, prevent, or otherwise control axial movement of the shaft  664  relative to the actuator  662 . The actuator  662 , thereby, may control transmission of force between the unsprung component  306  and the vehicle body  102 , for example, to dissipate energy from road disturbances and/or to maintain contact of the wheels connected to the unsprung component  306  with a road surface therebeneath. For example, the actuator  662  may function as a damper. The ball nut  662   d  may also be referred to as a ball screw nut. 
     The stationary structure  662 ″ is additionally configured to prevent rotation of the shaft  664  relative thereto. The torque applied by the motor  662   a  to the ball nut  662   d , in addition to applying an axial force to the shaft  664 , applies torque to the shaft  664  due to the inclination of the helical grooves  664   a  of the shaft  664  and the helical grooves  662   d ′ of the ball nut  662   d . The stationary structure  662 ″ and, in particular, the ball spline  662   e  resists this torque applied to the shaft  664  by the motor  662   a . As a result, torque is not transferred to the unsprung component  306  from the actuator  662 , which might otherwise cause undesired lateral movement of the unsprung component  306  (e.g., if a control arm intended to pivot vertically relative to the vehicle body  102 ). Such lateral movement may, for example, induce wear on pivot joints and/or bushings by which the unsprung component  306  is mounted to the vehicle body  102  and/or may induce unwanted forces into the steering system  150 . 
     The ball spline  662   e  engages the shaft  664  to prevent such torque from causing rotation of the shaft  664  relative to the actuator  662 . More particularly, a second set of recirculating balls (not shown; such as ball bearings) engage an outer axial groove  664   b  in the outer surface of the shaft  664  and an inner axial groove  662   e ′ of the ball spline  662   e . For example, the shaft  664  may include two outer axial grooves  664   b  spaced 180 degrees apart, while the ball spline  662   e  includes two inner axial grooves  662   e ′ spaced 180 degrees apart and corresponding thereto. Tangential force arising from the torque applied by the ball nut  662   d  to the shaft  664  is transferred via the second set of recirculating balls through the ball spline  662   e , so as to prevent rotation of the shaft  664  relative to the stationary structure  662 ″ of the actuator  662 . As an alternative to the ball spline  662   e , the shaft  664  may instead include key ways in which sliding or rolling keys ride and bear tangentially to transfer torque between the shaft  664  and the stationary structure  662 ″ to prevent rotation therebetween. 
     The rotating structure  662 ′ (i.e., the assembly of the rotor  662   b  and the ball nut  662   d ) is rotatably and axially supported by the stationary structure  662 ″ (i.e., by the assembly of the stator  662   c , the ball spline  662   e , the lower inner housing portion  662   g , and the upper inner housing portion  662   h ). For example, as shown, the rotating structure  662 ′ is rotatably coupled to the stationary structure  662 ″ with a lower bearing assembly  676  and an upper bearing assembly  678 . Each of the lower bearing assembly  676  and the upper bearing assembly  678  prevent radial movement between the rotating structure  662 ′ and the stationary structure  662 ″. Each of the lower bearing assembly  676  and the upper bearing assembly  678  may be a ball, roller, or needle bearing assembly or similar having an inner race and an outer race that rotate relative to each other with roller elements therebetween (e.g., balls, roller, needles, or the like; not shown). One or both of the lower bearing assembly  676  and the upper bearing assembly  678  may additionally be configured to prevent axial movement between the rotating structure  662 ′ and the stationary structure  662 ″, for example, being configured as a thrust bearing. For example, as shown, the lower bearing assembly  676  may be a thrust bearing. 
     The lower bearing assembly  676  may be positioned radially between the ball nut  662   d  and the lower inner housing portion  662   g . An inner race of the lower bearing assembly  676  is rotationally and axially fixed with the ball nut  662   d , so as to rotate therewith, and may be considered part of the rotating structure  662 ′. For example, the inner race engages an outer radial surface of the ball nut  662   d , so as to be rotationally and radially coupled thereto. The inner race is additionally held axially between an upper flange of the ball nut  662   d , which extends radially outward of the outer radial surface thereof, and a nut  680  or other fastener (e.g., a snap or lock ring) engaged with the outer radial surface at an intermediate height of the ball nut  662   d.    
     The outer race of the lower bearing assembly  676  is rotationally and axially fixed with the inner housing  662   f , and may be considered part of the stationary structure  662 ″. For example, the outer race engages an inner radial surface of the lower inner housing portion  662   g , so as to be rotationally and radially coupled thereto. The outer race is additionally held axially between a flange of the lower inner housing  662   f , which extends radially inward from the inner radial surface, and a snap ring  682  or other fastener (e.g., an externally threaded nut) engaged with the inner radial surface of the lower inner housing portion  662   g.    
     The upper bearing assembly  678  may be positioned radially between the rotor  662   b  and the inner housing  662   f . An inner race of the upper bearing assembly  678  is engaged with the outer radial surface of the spindle  662   b ″ of the rotor (e.g., being press-fit thereto), so as to prevent radial and rotational movement therebetween. The inner race may be considered part of the rotating structure  662 ′. An outer race of the upper bearing assembly  678  is engaged with an inner radial surface of the upper inner housing portion  662   h  to prevent radial and rotational movement therebetween (e.g., being press-fit thereto), while allowing the inner race to move rotationally but not radially relative thereto. The outer race may be considered part of the stationary structure  662 ″. 
     The lower bearing assembly  676  and the upper bearing assembly  678  are spaced apart axially, so as to resist any of the bending moments between the rotating structure  662 ′ and the stationary structure  662 ″ of the actuator  662 . For example, the lower bearing assembly  676  may be positioned below the motor (e.g., below the magnets  662   b ′ of the rotor  662   b  and the stator  662   c ) and resist radial loading between the rotating structure  662 ′ and the stationary structure  662 ″, such as between the ball nut  662   d  and the lower inner housing portion  662   g , which may arise from the bending moment. The upper bearing assembly  678  may be positioned above the motor (e.g., above the magnets  662   b ′ of the rotor  662   b  and the stator  662   c ) and resist radial loading between the rotor  662   b  (e.g., the spindle  662   b ″ thereof) and the upper inner housing portion  662   h , which may arise from the bending moment. 
     The ball nut  662   d  and the ball spline  662   e  are spaced apart axially, so as to resist any bending moments between the shaft  664  and the actuator  662 . More particularly, as a result of the rotating structure  662 ′ being fixed axially to the stationary structure  662 ″ (e.g., via the lower bearing assembly  676  being configured as a thrust bearing), the ball nut  662   d  and the ball spline  662   e  are fixed axially relative to each other with the ball nut  662   d  being arranged above the ball spline  662   e . As a bending moment is applied between the shaft  664  and the actuator  662 , the ball nut  662   d  and the ball spline  662   e  apply radial force to the shaft  664  at different axial positions on the shaft  664  to resist the bending moment applied thereto. 
     As referenced above, the outer housing  668  transfers force in the first load path (i.e., with the spring  366 ) and the second load path (i.e., with the actuator  662  and the shaft  664 ) between the unsprung component  306  and the vehicle body  102 . The outer housing  668  may, as shown, be configured as a multi-piece assembly. The outer housing  668  includes an upper outer housing  668   a , an intermediate outer housing  668   b , and a lower outer housing  668   c , which are generally annular structures that surround portions of the actuator  662  and/or the shaft  664 . 
     The upper outer housing  668   a  is coupled to the top mount  370  to transfer loading thereto. Various electronic circuitry and components (e.g., rotor encoder, position sensors, load cells; not shown) may be contained in a portion of an inner cavity of the outer housing  668 , which is defined by the upper outer housing  668   a . The upper inner isolator  374  may also be coupled to the upper outer housing  668   a  and the upper inner housing portion  662   h  (e.g., being positioned radially therebetween). 
     The intermediate outer housing  668   b  is coupled to (e.g., via threaded fasteners) and extends downward from the upper outer housing  668   a . The intermediate outer housing  668   b  defines a main portion of the inner cavity of the outer housing  668 , which generally contains the upper inner housing portion  662   h  and the motor  662   a  (i.e., the rotor  662   b  and the stator  662   c ). The lower inner isolator  376  may be coupled to the intermediate outer housing  668   b  and the lower inner housing portion  662   g  (e.g., being positioned radially therebetween). 
     The lower outer housing  668   c  is coupled to (e.g., via male-to-female threaded engagement) and extends downward from the intermediate outer housing  668   b . The lower outer housing  668   c  defines a portion of the cavity of the outer housing  668 , which contains portions of the lower inner housing portion  662   g  and the ball nut  662   d , either of which may protrude axially below a bottom end of the lower outer housing  668   c . The lower outer housing  668   c  may also function as a spring seat that receives the spring  366  therein and/or thereagainst (e.g., with an isolator therebetween) for transferring loading of the first load path thereto. The lower outer housing  668   c  may be axially adjustable relative to the intermediate outer housing  668   b , for example, via the threaded engagement therebetween, so as to form an adjustable spring seat. 
     As referenced above and as shown, the actuator  662  is coupled to the outer housing  668  via the upper inner isolator  374  and the lower inner isolator  376 , which may be configured to function as described previously for coupling and transferring loading between the actuator  262  and the housing  368 . Each of the isolators may be tube isolators having inner and outer rigid ring members and an intermediate compliant ring member therebetween. The inner and outer ring members are, respectively coupled to the inner housing (e.g., to the lower inner housing portion  662   g  or the upper inner housing portion  662   h ) and the outer housing  668 , while the intermediate compliant ring member provides compliance therebetween. The upper inner isolator  374  and the lower inner isolator  376  function to transfer axial loading of the second load path between the actuator  662  and the outer housing  668 , while dampening vibrations or other disturbances generated by the actuator  662  (e.g., due to operation of the motor, movement of the recirculating balls within the ball nut  662   d  and the ball spline  662   e , other friction) and/or vibrations or other disturbances arising external to the actuator (e.g., from road disturbances acting on the unsprung component  306 ). Additionally, the upper inner isolator  374  and the lower inner isolator  376  are spaced apart axially, so as to resist bending moment between the actuator  662  and the outer housing  668 . 
     As shown in  FIG.  6 B , the suspension system  660  may also include various electronics, which are depicted schematically. These electronics are configured to monitor conditions of the suspension system  660  (e.g., force and displacement), which may be used for controlling the suspension system  660  and other systems of the vehicle  100 . For example, the top mount  370  may include one or more force sensors  671 , such as a load cell that measures force transferred between the housing  668  and the top mount (i.e., the forces of both the first load path and the second load path). The actuator  662  may include motor electronics  663 , which may include various electronics for providing power to or drawing power from the motor  662  and controlling operation thereof (e.g., a rotor encoder). The actuator  662  may also include a position sensor  665  for measuring a position of the shaft  664  relative to the actuator  662  (e.g., for determining a length of the suspension system  660  or a height of the vehicle  100  (e.g., between the vehicle body  102  and the unsprung component). Referring to  FIG.  6 F , the electronics (i.e., the force sensors  671 , the motor electronics  663 , and the position sensor  665 ) may be in communication with the control system  180 , which may provide control signals to each of the suspension systems  660  (e.g., four suspension systems  660 ) for control thereof. 
     Referring to  FIGS.  7 A- 7 B , a suspension system  760 , or strut assembly or system, may be used as any of the suspension systems  160   fl ,  160   fr ,  160   rl ,  160   rr  shown in  FIG.  1   . The suspension system  760  is coupled at an upper end thereof to the vehicle body  102  and at a lower end thereof to the unsprung component  306 . The suspension system  760  is configured in some aspects similar to the suspension systems  160  and  660  described previously. Where common reference numerals are used between the suspension system  760  and the suspension systems  160  and  660  to identify components, features, or other elements of the suspension system  760 , the discussion of the suspension systems  160  and  660  may be referred to for further details of such components, features, or other elements. 
     The suspension system  760  generally includes the actuator  662  and the shaft  664  and forms an air spring  766 . As discussed in further detail below, the air spring  766  forms the first load path between the unsprung component  306  and the vehicle body  102 , which is parallel to the second load path formed by the actuator  662 , the shaft  664 , and an upper housing  768 . The air spring  766 , as with the first load path described previously, transfers the preload (i.e., the weight of the vehicle  100 ) between the unsprung component  306  and the vehicle body  102 . The actuator  662  and the shaft  664  may be configured substantially as described previously to form the second load path between the unsprung component  306  and the vehicle body  102 . 
     The suspension system  760  includes components of the actuator  662 , the shaft  664 , the upper housing  768 , a lower housing  770 , and a membrane  772 , as well as a top mount  774 , and a bottom mount  778 . 
     The upper housing  768  is a generally rigid and annular structure, which extends downward from the top mount  774  to surround all or a portion of the actuator  662 . As discussed in further detail below, the upper housing  768  may define an upper chamber  766   b  of a pressurized cavity  766   a  of the air spring  766 . The upper housing  768  is coupled to the top mount  774  and extends downward therefrom to terminate at a bottom end thereof positioned below the ball nut  662   d , for example, at least partially overlapping the ball spline  662   e . The upper housing  768  may also reduce in diameter moving downward from the top mount  774 , for example, reducing in diameter in a stepped or gradual manner below the stator  662   c  of the motor  662   a . The upper housing  768  may, as shown, be a unitary component but may be formed as an assembly of multiple components (e.g., similar to the upper outer housing  668   a  and the intermediate outer housing  668   b ). 
     The upper housing  768  additionally includes a port  768   a  by which the air spring  766  receives pressurized gas (e.g., pressurize air) from an air source (not shown) to increase the amount of air in the pressurized cavity  766   a  to raise the vehicle  100 . Air may also be released from the air spring  766  through the port  768   a  to lessen the amount of air in the pressurized cavity  766   a  to lower the vehicle  100 . 
     The upper housing  768  is coupled to the top mount  774  with an isolator  776 , which forms a compliant coupling therebetween, while limiting rotational, radial, and axial movement therebetween. The isolator  776  may, for example, be a tube isolator having rigid inner and outer ring members coupled to and separated by a compliant intermediate ring member. The isolator  776  may be positioned radially between and be rigidly coupled to an inner radial portion of the upper housing  768  (e.g., an inner surface thereof) and an outer radial portion of the top mount  774  (e.g., a downward extending annular flange thereof). The isolator  776  transfers force of the second load path between the upper housing  768  and the top mount  774 . The isolator  776  additionally functions to seal the upper housing  768  to the top mount  774 , so as to seal the pressurized cavity  766   a  with the top mount  774 . 
     The top mount  774  is a structure that functions to both seal the pressurized cavity  766   a  and mechanically connect the suspension system  760  the vehicle body  102 . The top mount  774  may include one or more structures and/or components that are coupled to each other to form the top mount  774  as an assembly. For example, the top mount  774  may include, among other components, a lower structure that functions, in part, to seal the pressurized cavity  766   a  and an upper structure that functions to couple the suspension system  760  to the vehicle body  102 . The top mount  774  may include further components and/or functions, such as including a load cell, which measures force transfer between the suspension system  760  and the vehicle body  102 . 
     The lower housing  770  is generally rigid and annular structure, which is coupled to and extends upward from a bottom mount  778  to terminate at an upper end thereof. As the vehicle body  102  and the unsprung component  306  and, thereby, the top mount  774  and the bottom mount  778  move toward and away from each other, the upper end of the lower housing  770  changes axial position relative to the lower end of the upper housing  768 . In some positions, the lower housing  770  axially overlaps the upper housing  768 . The upper end of the lower housing  770  has a larger diameter than the lower end of the upper housing  768 , such that the upper housing  768  may be received within the lower housing  770 . A circumferential gap  766   d  is defined between the upper end of the lower housing  770  and the lower end of the upper housing  768 . The lower housing  770  may be formed, as shown, as a unitary component formed integrally with a portion of the bottom mount  778 , or may be formed as an assembly of multiple components (e.g., being formed separately from and coupled to the bottom mount  778 ). 
     The bottom mount  778  is a structure that functions to both seal the pressurized cavity  766   a  and mechanically connect the suspension system  760  the unsprung component  306 . The bottom mount  778  may include one or more structures and/or components that are coupled to each other to form the bottom mount  778  as an assembly. For example, the bottom mount  778  may include, among other components, an upper structure that functions, in part, to seal the pressurized cavity  766   a  and connect to the shaft  664 , and include a lower structure that functions to couple the suspension system  760  to the unsprung component  306 . The shaft  664  is coupled to the bottom mount  778  for transferring force of the second load path therebetween. 
     The membrane  772  extends radially between the upper end of the lower housing  770  and the lower end of the upper housing  768  to seal the circumferential gap  766   d  therebetween. The membrane  772  thereby seals the pressurized cavity  766   a . The membrane  772  may be formed of a polymeric (e.g., rubber) material or any other suitable flexible material. 
     The membrane  772  is configured to form the air spring  766  as a rolling lobe air spring as is understood in the art. The membrane  772  includes an inner membrane portion  772   a  coupled to the lower end of the upper housing  768  and an outer membrane portion  772   b  coupled to the upper end of the lower housing  770 . As the vehicle body  102  and the unsprung component  306  and, thereby, the upper housing  768  and the lower housing  770  move toward and away from each other, the inner membrane portion  772   a  and the outer membrane portion  772   b  translate axially relative to each other. 
     The actuator  662  is coupled to the upper housing  768  to prevent rotational and axial movement therebetween. For example, the actuator may be coupled to the upper housing  768  with one or more support structures  780  that extend radially between the actuator  662  and the upper housing  768 . The one or more support structures  780  may, for example, couple the upper inner housing portion  662   h  to the upper housing  768 . The support structures  780  may be positioned above the motor  662   a  (e.g., above the stator  662   c  and/or the upper bearing assembly  678 ). The one or more support structures  780  additionally allow air flow between an upper chamber  766   b  and a lower chamber  766   c  of the pressurized cavity  766   a  as discussed in further detail below (e.g., being configured as spokes). As a result, forces of the second load path are transferred between the actuator  662  and the upper housing  768  with the support structures  780 . Thus, the second load path transfers force between the unsprung component  306  to the vehicle body  102  from the bottom mount  778  to the shaft  664  to the actuator  662  to the upper housing  768  to the isolator  776  and to the top mount  774 . 
     As referenced above, the air spring  766  forms the first load path between vehicle body  102  and the unsprung component  306 , while the actuator  662 , the shaft  664 , and the upper housing  768  form the second load path in parallel to the first load path. Referring first to the first load path, the air spring  766  includes the pressurized cavity  766   a , which is a sealed chamber containing pressurized gas or air. The cavity  766   a  is generally defined by the upper housing  768 , the lower housing  770 , and the membrane  772  sealed therebetween. The cavity  766   a  may also extend from the top mount  774  to the bottom mount  778 , and may be defined therebetween. Force of the first load path is transferred by the pressurized gas acting on an upper end and a lower end of the pressurized cavity  766   a , for example, formed by the top mount  774  and the bottom mount  778 , respectively. Referring to  FIG.  7 B , the pressurized cavity  766   a  is represented by the area shown in cross-hatching. As discussed in further detail below, the actuator  662  and the shaft  664  are contained in the pressurized cavity  766   a , so as to be subject to the air pressure therein. 
     As the vehicle body  102  and the unsprung component  306  move relative to each other, the volume of the pressurized cavity  766   a  changes to further compress or decompress a given amount of air therein, such that the suspension system  760  exerts more or less force, respectively, between the vehicle body  102  and the unsprung component  306 . Further, for a given pressure, air may be selectively added to or removed from the pressurized cavity  766   a , so as to increase the volume of the pressurized cavity  766   a  and, thereby, change a length of the suspension system  760  and a distance between the vehicle body  102  and the unsprung component  306 . As the length of the suspension system changes (e.g., from different forces applied between the vehicle body  102  and the unsprung component, from forces applied by the actuator  662  between the bottom mount  778  and the top mount  774 , and/or as air is added to or removed from the cavity  666   a ), the upper housing  768  and the lower housing  770  move axially relative to each other, for example, with the upper housing  768  being received and/or sliding within the lower housing  770 . 
     As referenced above, the pressurized cavity  766   a  includes the upper chamber  766   b  and the lower chamber  766   c , which are in fluidic communication with each other. The upper chamber  766   b  is generally defined by the upper housing  768 . The lower chamber  766   c  is generally defined by the lower housing  770  and the membrane  772 . The actuator  662  and the upper housing  768  generally form an assembly (e.g., a first piston assembly of the air spring  766 ) that is movable relative to the bottom mount  778 , which is permitted or allowed to move due to the membrane  772  being flexible. The top mount  774  generally forms another assembly (e.g., a second piston assembly of the air spring  766 ) that is movable relative to the housing  768 , which is permitted or allowed to move due to the isolator  776  having compliance. The first piston assembly and the second piston assembly may have effective piston areas that are approximately equal, for example, being defined generally as the areas within, respectively, a mid-point between the inner housing  662   g  and the lower housing  770  (e.g., a mid-point of the flexible membrane) and within a mid-point of the intermediate compliant ring of the isolator  776 . By having effective piston areas that are approximately equal may allow for an axial static load on the actuator  662  to be approximately zero (e.g., from the common pressure in the upper chamber  776   b  and the lower chamber  766   c  applying approximately equal upward and downward forces to the first piston assembly that includes the actuator  662 . The effective piston areas may be approximately equal by, for example, being within 25%, 15%, 10%, 5%, or 2% of each other. Approximate equal piston areas may be applied to the further suspension systems  860 ,  960 ,  1060 , and  1160  described below. 
     The upper chamber  766   b  and the lower chamber  766   c  are in fluidic communication with each other, so as to maintain a generally even pressure therein. As shown in  FIGS.  7 A and  7 B , a circumferential gap  766   d  (e.g., an annular plenum) extends between the upper chamber  776   b  and the lower chamber  766   c , so as to maintain fluidic communication therebetween. The circumferential gap  766   d , for example, is defined radially between the upper housing  768  and the inner housing  662   f  of the actuator  662 , and circumferentially around an axis of the shaft  664 . Further, as referenced above, the one or more support structures  780 , which couple the actuator  662  to the upper housing  768 , allow air flow between the upper chamber  776   b  and the lower chamber  766   c  through the circumferential gap  766   d . For example, the support structures  780  may be spokes that are circumferentially spaced apart from each other to provide flow paths therebetween. 
     As the suspension system  760  changes in length, the volume of the pressurized cavity  766   a  changes and, in particular, the volume of the lower chamber  766   c  changes, while the volume of the upper chamber  766   b  stays generally constant. Thus, as the volume of the pressurized cavity  766   a  increases or decreases for a given amount of air, the air flows, respectively, from the lower chamber  766   c  to the upper chamber  766   b , or from the lower chamber  766   c  to the upper chamber  766   b , to maintain generally even air pressure therebetween. It should be noted, however, that pressure slight variances between the upper chamber  766   b  and the lower chamber  766   c  may occur as the air flows therebetween and is restricted within the circumferential gap  766   d.    
     Referring to the second load path, the second load path is formed by the actuator  662 , the shaft  664 , and the upper housing  768  and is in parallel to the first load path between the top mount  774  and the bottom mount  778  and, thereby, between the vehicle body  102  and the unsprung component  306 . More particularly, force is transferred between the top mount  774  and the upper housing  768  via the isolator  776 , between upper housing  768  and the actuator  662  via the support structures  780 , and between the actuator  662  (i.e., the ball nut  662   d  thereof) and the bottom mount  778  via the shaft  664 . 
     As mentioned above, the first load path supports the weight of the vehicle body  102  on the unsprung component  306 , as well as a portion of the dynamic loading to the vehicle body  102  (e.g., from weight transfer as the vehicle  100  goes around a corner or accelerates, or as masses move within the vehicle  100 ) or dynamic loading to the unsprung component  306  (e.g., as a wheel goes over a bump or through a pothole). The force in the first load path is generally a function of a spring constant of the air spring  766  and the length (e.g., displacement) of the suspension system  760  (e.g., the distance between the vehicle body  102  and the unsprung component  306 ). The spring constant of the air spring  766  may be controlled with addition or removal of air from the pressurized cavity  766   a , but may be controlled in a relatively small range (e.g., +/−20%) and at a relatively low speed (e.g., bandwidth) that is limited by the rate of air supply to or release from the pressurized cavity  766   a.    
     The second load path is configured control force transfer between the vehicle body  102  and the unsprung component  306  due to the dynamic loading, for example, functioning as a damper. The force in the second load path is controlled directly by the actuator  662  (i.e., by the motor  662   a  applying a torque to the ball nut  662   d  that in turn applies an axial force to the shaft  664 ), which may be controlled in a large range (e.g., 0 kN+/−a force capacity) and at a relatively high speed (e.g., bandwidth), as compared to first load path by the air spring  766 . As a result, the actuator  662  may be operated to selectively apply axial force to the shaft  664  (i.e., by selectively applying torque from the motor  662   a  to the ball nut  662   d ) to control force transmission from the unsprung component  306  to the vehicle body  102  in response to or anticipation of dynamic loading (e.g., in response to or in anticipation of road disturbances), while the air spring  766  may or may not be controlled in response to or in anticipation of dynamic loading. 
     As referenced above, the pressurized cavity  766   a  of the air spring  766  extends from an upper end to a lower end of the suspension system  760  (e.g., between the top mount  774  and the bottom mount  778 ), and may also contain a least a portion of the actuator  662  (e.g., one, or more, or all of the motor  662   a , including both the rotor  662   b  and the stator  662   c , the ball nut  662   d , and the ball spline  662   e ) and the shaft  664 . Various advantages may be offered by this configuration, as opposed to an air spring instead being arranged entirely below the actuator  662 . For example, the usable volume of the pressurized cavity  766   a  may be larger and/or allow for narrower packaging of the air spring  766 , as compared to an air spring mounted below the actuator  662 . Additionally, an air spring mounted below the actuator  662  might otherwise need to be sealed to and move along the shaft  664 , which may be difficult to perform given the grooves  664   a ,  664   b  in the outer surface thereof. Still further, the actuator  662  is protected from the outside environment by being located in the pressurized cavity  766   a  without the need for a protective shroud (e.g., a bellows). 
     As shown in  FIG.  7 A , the suspension system  760  may also include various electronics, which are depicted schematically. These electronics may include the force sensors  671  described previously and incorporated into the top mount  771 , the motor electronics  663 , and the position sensor  665 , and may also include a pressure sensor  766   f . Such electronics may also be included in the suspension systems  860 ,  960 ,  1060 , and  1160  described below. Referring to  FIG.  7 C , the electronics (i.e., the force sensors  671 , the motor electronics  663 , the position sensor  665 , and the pressure sensor  766   f ) may be in communication with the control system  180 , which may provide control signals to each of the suspension systems  660  (e.g., four suspension systems  660 ) for control thereof. The vehicle may additionally include pressurized gas source  790 , which is in fluidic communication with each of the suspension systems  760  of the vehicle  100  (e.g., four) and which may be controlled by the control system  180  for supplying or releasing pressurized air from the air springs  766  of each of the suspension systems  760 . 
     Referring to  FIGS.  8 A- 8 B , a suspension system  860  is a variation of the suspension system  760 . The suspension system  860  generally includes an actuator  862 , the shaft  664 , an air spring  866  having a pressurized cavity  866   a , an upper housing  868 , the lower housing  770 , and the membrane  772 . The air spring  866  forms the first load path between the top mount  774  and the bottom mount  778 . The actuator  862  and the shaft  664  form the second load path between the top mount  774  and the bottom mount  778 , and the load path may also include the upper housing  868 . 
     The actuator  862  is configured similar to the actuator  662  (e.g., by including the motor  662   a , the ball nut  662   d , the ball spline  662   e , and the inner housing  662   f ) with variations for mounting to the upper housing  868  and for communicating air between an upper chamber  866   b  and a lower chamber  866   c  of the pressurized cavity  866   a . The shaft  664  is configured as describe previously. The air spring  866  is configured similar to the actuator  662  (e.g., by being defined by the upper housing  868 , the lower housing  770 , and the membrane  772 ) with variations to the configuration of the upper chamber  866   b  of the pressurized cavity  866   a  and in communicating air between the upper chamber  866   b  and the lower chamber  866   c . The upper housing  868  is configured similar to the upper housing  768  with variations for mounting the actuator  862  thereto, in defining the upper chamber  866   b , and in connecting to the top mount  774 . The lower housing  770  and the membrane  772  are configured as described previously. These variations are described in further detail below. 
     The actuator  862  is mounted to the upper housing  868  and/or to the top mount  774  with an upper isolator  876   a  and a lower isolator  876   b . Each of the upper isolator  876   a  and the lower isolator  876   b  are configured similar to the isolator  776  described previously by including inner and outer rigid rings between which is an intermediate compliant ring. The upper isolator  876   a  is positioned radially between and is rigidly coupled to the upper housing  868  and/or the top mount  774  and to the actuator  862 . For example, the outer rigid ring of the upper isolator  776   a  may be rigidly coupled to an inner surface of the upper housing  868  and/or to the top mount  774   a , while the inner rigid ring of the upper isolator  776   a  may be rigidly coupled to an outer radial surface of the inner housing  662   f , such as to the upper inner housing portion  662   h ). The upper isolator  876   a  is positioned axially above the motor  662   a , such as above the stator  662   c  and/or the rotor  662   b ). 
     The lower isolator  876   b  is positioned radially between and is rigidly coupled to the upper housing  868  and to the actuator  862 . For example, the outer rigid ring of the lower isolator  876   b  may be rigidly coupled to an inner radial surface of the upper housing  868 , while the inner rigid ring of the lower isolator  876   b  may be rigidly coupled to an outer radial surface of the inner housing  662   f , such as to the lower inner housing portion  662   g . The lower isolator  876   b  is spaced axially apart from the upper isolator  876   a . For example, the lower isolator  876   b  is positioned below a majority of an axial length of the motor  662   a  (e.g., below a majority of the stator  662   c ), such as being coupled to the lower inner housing portion  662   g . By being spaced apart axially, the upper isolator  876   a  and the lower isolator  876   b  cooperatively resist a bending moment applied to the suspension system  860 , for example, between the actuator  862   a  and the upper housing  868 . 
     The actuator  862  is additionally configured to allow air to flow therethrough between the upper chamber  866   b  and the lower chamber  866   c  of the pressurized cavity  866   a  of the air spring  866 . Referring to  FIG.  8 B , the pressurized cavity  866   a , which is represented by cross-hatching, extends axially through the actuator  862   a . Air communicates between the upper chamber  866   b  and the lower chamber  866   c  through the actuator, such as through axial channels in the inner housing  662   f , channels and/or gaps between the inner housing  662   f  and the stator  662   c , and/or between the rotor  662   b  and the stator  662   c , such channels and/or gaps being illustrated schematically in  FIG.  8 B . 
     The cavity  866   a  is generally defined by the actuator  862  (e.g., the inner housing  662   f  thereof), the upper housing  868 , the lower housing  770 , the membrane  772 , as well as between the top mount  774  and the bottom mount  778 . The upper chamber  866   b  of the cavity is generally positioned within the upper housing  868 , but is not defined or formed thereby, and is instead defined or formed by the inner housing  662   f  of the actuator  862 , such that the upper housing  868  is isolated from the upper chamber  866   b  (e.g., is not in fluidic communication therewith or under pressure). As shown, the upper isolator  876   a  and the lower isolator  876   b  form a seal between the actuator  862  (e.g., the inner housing  662   f  thereof) and the upper housing  868 , such that an annular cavity  868   e  defined radially between the actuator  862  and the upper housing  868  and axially between the upper isolator  876   a  and the lower isolator  876   b  is not in fluidic communication with the pressurized cavity  866   a  (e.g., the upper chamber  866   b  or otherwise) of the air spring  866 . As a result, an upper portion of the upper housing  868  is not subject to the air pressure within the pressurized cavity  866   a.    
     The upper housing  868  may be rigidly coupled to the top mount  774 . For example, the upper housing  868  may be coupled directly to the upper housing  868  and/or to the outer rigid ring of the isolator  776  that is in turn rigidly coupled to the top mount  774 . 
     A port  868   a  may be a variation of the port  768   a  and be configured to communicate air to and from the upper chamber  866   b  without communicating air to the region between sealed and unpressurized region between the upper housing  868  and the inner housing  662   f  of the actuator  662 . 
     The suspension system  860  achieves various advantages of the suspension system  760 . For example, the pressurized cavity  866   a  of the air spring  866  extends from an upper end to a lower end of the suspension system  860  (e.g., between the top mount  774  and the bottom mount  778 ), so as to provide a relatively large volume and/or narrow packaging as compared to an air spring instead mounted below the actuator  662 . The actuator  862 , by being contained within upper housing  868  is protected from the outside environment, while the motor  662   a  (e.g., the rotor  662   b  and the stator  662   c ) subject to the air pressure of the pressurized cavity  866   a ). Further, by containing the shaft  664  within the pressurized cavity  866   a , a moving seal does not need to be formed therewith, which may be difficult to perform reliably with the grooves  664   a ,  664   b  thereon. 
     As referenced above, the first load path is formed by the air spring  866 , whereby pressurized gas in the cavity  866   a  transfers force of the first load path between the top mount  774  and the bottom mount  778 . The second load path is in parallel to the first load path and is formed by the actuator  862 , whereby force of the second load path is transferred between the top mount  774  and the bottom mount  778  by the shaft  664 , the ball nut  662   d , the inner housing  662   f  of the actuator  662 , the isolators  876   a ,  876   b  (e.g., by the compliant intermediate ring thereof), and the housing  868 . The housing  868  may function to both define the pressurized cavity  866   a , while also transferring force of the second load path. The isolator  876   a  may function to both seal the pressurized cavity  866   a  of the air spring  866 , while also transferring force of the second load path. The pressurized cavity  866   a  may be cooperatively defined by the top mount  774 , the isolator  776 , the housing  868 , the flexible membrane  772 , and the bottom mount  778 , and may be further defined by the lower housing  770 . 
     Refer to the discussions above of the suspension systems  160 ,  660 ,  760  for further description of other parts and features of the suspension system  860 , including those identified in  FIGS.  8 A- 8 B . 
     Referring to  FIG.  9   , a suspension system  960  is a variation of the suspension system  860 . The suspension system  860  generally includes the actuator  862 , the shaft  664 , an air spring  966  having the pressurized cavity  966   a , an upper housing  968 , the lower housing  770 , and the membrane  772 . The air spring  966  forms the first load path between the top mount  774  and the bottom mount  778 . The actuator  862  and the shaft  664  form the second load path between the top mount  774  and the bottom mount  778 , and the load path also includes the upper housing  968 . 
     The suspension system  960  differs from the suspension system  860  in that an annular cavity  968   e , which is defined radially between the upper housing  968  and the actuator  862  (similar to the annular cavity  868   e ), is in communication with an upper chamber  966   b  of the cavity. As a result, the pressurized cavity  966   a  of the air spring  966  is defined or otherwise formed by the upper housing  968 , which retains the air pressure within the pressurized cavity  966   a . The actuator  862  and, in particular, the inner housing  662   f  thereof does not seal the pressurized cavity  866   a , but is still contained within the pressurized cavity  866   a  and subject to the pressure therein. 
     Refer to the descriptions above of the suspension systems  160 ,  660 ,  760 ,  860  for further description of other parts and features of the suspension system  960 , including those identified in  FIG.  9   . 
     Referring to  FIG.  10   , a suspension system  1060  is a variation of the suspension system  960 . The suspension system  1060  generally includes the actuator  862  (or may alternatively include the actuator  662 ), the shaft  664 , the air spring  966  having the pressurized cavity  966   a , an upper housing  1068 , the lower housing  770 , and the membrane  772 . The air spring  966  forms the first load path between the top mount  774  and the bottom mount  778 . The actuator  862  and the shaft  664  form the second load path between the top mount  774  and the bottom mount  778 , and the load path may also include the upper housing  868 . 
     The suspension system  1060  differs from the suspension systems  760 ,  860 ,  960  in that the upper housing  1068  does not form part of the second load path from the actuator  862  to the top mount  774 . The upper isolator  876   a  and the lower isolator  876   b  are omitted. Rather, an upper end of the actuator  862  is coupled to the top mount  774  with an intermediate top mount  1076  being arranged therebetween. The intermediate top mount  1076  transfers forces of the second load path between the actuator  862  (e.g., the inner housing  862   g  thereof). The intermediate top mount  1076  may also provide similar damping functions of the upper isolator  876   a  and/or the lower isolator  876   b  by restraining motion between the actuator  862  and the top mount  774  (e.g., in rotational, radial, and axial directions) damping vibrations therebetween (e.g., from operation of the actuator  862  and/or from road disturbances). 
     Refer to the descriptions above of the suspension systems  160 ,  660 ,  760 ,  860 ,  960  for further description of other parts and features of the suspension system  1060 , including those identified in  FIG.  10   . 
     Referring to  FIGS.  11 A- 11 B , a suspension system  1160  is a variation of the suspension system  860 . The suspension system  1160  generally includes an actuator  1162 , the shaft  664 , an air spring  1166  having a pressurized cavity  1166   a , the lower housing  770 , and the membrane  772 . The air spring  1166  forms the first load path between the top mount  774  and the bottom mount  778 . The actuator  1162  and the shaft  664  form the second load path between the top mount  774  and the bottom mount  778 . 
     A primary difference between the suspension system  1160  and the suspension system  860  is the omission of the upper housing  868 . Without the upper housing  868 , the pressurized cavity  1166   a  is formed by a housing  1162   f  of the actuator  1162 , the lower housing  770 , and the membrane  772  that seals lower housing  770  to the housing  1162   f  of the actuator  1162 . The omission of the upper housing  868  may comparatively simplify and reduce weight of the suspension system  1160 . The cavity  1166   a  is identified by cross-hatching in  FIG.  11 B . 
     The actuator  1162  is a variation of the actuator  862 . The actuator  1162 , includes the motor  662   a  (i.e., including the rotor  662   b  and the stator  662   c ), the ball nut  662   d , and the ball spline  662   e , and a housing  1162   f . The housing  1162   f  is a variation of the inner housing  662   f , which extends further downward relative to the actuator  1162  than the inner housing  662   f  relative to the actuator  662 . 
     The housing  1162   f  is a rigid annular structure that generally includes an upper housing portion  1162   g  and a lower housing portion  1162   h , which are coupled to each other or integrally formed with each other as described previously. The housing  1162   f  may include more or fewer components than the upper housing portion  1162   g  and the lower housing portion  1162   h.    
     The housing  1162   f  may be configured similar to the upper inner housing portion  662   h , for example, by surrounding the motor  662   a  (e.g., being fixedly coupled to the stator  662   c  and/or rotatably supporting the rotor  662   b  with the upper bearing assembly  678 ) and including cooling passages (shown; not labeled). 
     An upper end of the actuator  1162  (e.g., an upper end of the upper housing portion  1162   g ) is coupled to the top mount  774  with an isolator  1176 . The isolator  1176  may be configured as a tube isolator or bushing similar to the isolator  776 , for example, by having inner and outer rigid rings coupled to and separated by an intermediate compliant ring. The isolator  1176  is rigidly coupled to each of the actuator  1162  and the top mount  774 , for example, with the outer rigid ring being coupled to the top mount  774  and the inner rigid ring being coupled to the actuator  1162  (e.g., to the housing  1162   f , such as the upper housing portion  1162   g  on an outer radial surface thereof). 
     In an alternative arrangement, the outer rigid ring of the isolator  1176  may be coupled to the housing  1162   f  of the actuator  1162  (e.g., to an inner surface thereof), while the inner rigid ring of the isolator  1176  is coupled to the top mount  774  (e.g., to an axially extending portion, such as the annular flange described above with respect to the suspension system  760  or a load cell of the top mount  774 ). Various packaging advantages may be provided by providing the isolator  1176  radially inward of the housing  1162   f , for example, by allowing the load cell of the top mount  774  to be smaller and/or positioned within the isolator  1176 . The housing  1162   f  of the actuator  1162  may be considered an outer housing of the suspension system  1160 . 
     The upper housing portion  1162   g  defines an upper chamber  1166   b  of the pressurized cavity  1166   a . The isolator  1176  functions to seal the housing  1162   f  of the actuator  1162  to the top mount  774  to define a portion of the pressurized cavity  1166   a  of the air spring  1166 . The upper chamber  1166   b , similar to the upper chambers  766   b ,  866   b  described previously, may contain therein the motor  662   a  (e.g., the rotor  662   b  and the stator  662   c ), which is subject the pressurized air. 
     The upper housing portion  1162   g  additionally includes a port  1168   a  by which air is communicated into and out of the pressurized cavity  1166   a . For example, as described above, air may be added to or removed from the pressurized cavity  1166   a  to raise or lower a ride height of the vehicle (e.g., by displacing the vehicle body  102  relative to the unsprung component  306 ). 
     The lower housing portion  1162   h  may be configured, in various aspects, similar to the lower inner housing portion  662   g , for example, by including an inner annular portion  1162   j  that surrounds the ball nut  662   d  and/or the ball spline  662   e  (e.g., being fixedly coupled to the ball spline  662   e  and/or rotatably supporting the ball nut  662   d  with a bearing assembly  676 , such as a thrust bearing). 
     The lower housing portion  1162   h  is sealingly coupled to the lower housing  770  with the membrane  772 , such that the lower housing portion  1162   h , the housing  770 , and the membrane  772  cooperatively define a lower chamber  1166   c  of the pressurized cavity  1166   a  of the air spring. For example, the lower housing portion  1162   h  includes an outer annular portion  1162   k  to which the membrane  772  is coupled. As the suspension system  1160  changes length, the outer annular portion  1162   k  of the lower housing portion  1162   h  and the lower housing  770  translate relative to each other (e.g., the lower housing  770  receiving the housing  1162   f  therein), while inner and outer portions of the membrane  772  translate past each other (as described previously). 
     The outer annular portion  1162   k  may be positioned radially outward of the inner annular portion  1162   j , so as to define an annular channel  11621  therebetween. As the length of the suspension system  1160  changes or air is added to or removed from the pressurized cavity  1166   a , air passes through the annular channel  11621  between the upper chamber  1166   b  and the lower chamber  1166   c  of the pressurized cavity  1166   a.    
     The actuator  1162  is configured similar to the actuator  862  to allow air to pass therethrough between the upper chamber  1166   b  and the lower chamber  1166   c , such as through axial channels in the housing  1162   f , channels and/or gaps between the housing  1162   f  and the stator  662   c  and/or between the rotor  662   b  and the stator  662   c , such channels and/or gaps being illustrated schematically in  FIG.  11 B . 
     As referenced above, the first load path is formed by the air spring  1166 , whereby pressurized gas in the cavity  1166   a  transfers force of the first load path between the top mount  774  and the bottom mount  778 . The second load path is in parallel to the first load path and is formed by the actuator  1162 , whereby force of the second load path is transferred between the top mount  774  and the bottom mount  778  by the shaft  664 , the ball nut  662   d , the housing  1162   f , and the isolator  1176  (e.g., by the compliant intermediate ring thereof). The housing  1162   f  may function to both define the pressurized cavity  1166   a , while also transferring force of the second load path. The isolator  1176  may function to both seal the pressurized cavity  1166   a  of the air spring  1166 , while also transferring force of the second load path. The pressurized cavity  1166   a  may be cooperatively defined by the top mount  1174 , the isolator  1176 , the housing  1162   f  of the actuator  1162 , the flexible membrane  772 , and the bottom mount  774 , and may be further defined by another housing coupled to the bottom mount  774 . The housing  1162   f  of the actuator  1162  may form an outer housing of the suspension system  1160 . 
     Refer to the descriptions above of the suspension systems  160 ,  660 ,  760 ,  860 ,  960 ,  1060  for further description of other parts and features of the suspension system  1160 , including those identified in  FIGS.  11 A- 11 B . 
     While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.

Metadata:
Filing Date: 20220503
Publication Date: 20230718
Grant Date: 20230718
Priority Date: 20170508
Inventors: HALL, JONATHAN L.
Dawson, Jacob L.
KEAS, PAUL J.
CARTER, TROY A.
Smith, Roland R.
Assignee: APPLE INC
CPC Classifications: [{"code": "B60G17/0521", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G11/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G15/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G15/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/0155", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16H25/2204", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/152", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/322", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/41", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/201", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2800/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/2075", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/2078", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/052", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G17/0521", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G11/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/0155", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16H25/2204", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/152", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/204", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/2078", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G11/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G15/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G15/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/0155", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/152", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/322", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/41", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/201", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2800/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H25/2204", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16H2025/2075", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/2078", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0523", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G17/0155", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G11/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16H25/2204", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16H25/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/152", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 62165673