PATENT DOCUMENT

Publication Number: US-11124035-B1
Application Number: US-201816115603-A
Country: US
Kind Code: B1

Title: Multi-stage active suspension actuator

Abstract:
A suspension actuator includes an upper mount, a lower mount, a first actuator mechanism, and a second actuator mechanism. The upper mount is connectable to a sprung mass of a vehicle. The lower mount is connectable to an unsprung mass of the vehicle. The first actuator mechanism forms a first load path between the upper mount and the lower mount. The first actuator mechanism is one of an electromagnetic linear actuator mechanism or a ball screw actuator mechanism. The second actuator mechanism forms a second load path in parallel with the first load path between the upper mount and the lower mount. The second actuator mechanism is one of a mechanical linear actuator mechanism, an air spring actuator mechanism, or a hydraulic actuator mechanism.

Claims:
What is claimed is: 
     
       1. A suspension actuator comprising:
 an upper mount connectable to a sprung mass of a vehicle; 
 a lower mount connectable to an unsprung mass of the vehicle; 
 a first actuator forming a first load path between the upper mount and the lower mount, wherein the first actuator is a ball screw actuator; 
 a second actuator forming a second load path in parallel with the first load path between the upper mount and the lower mount, wherein the second actuator is a hydraulic actuator; and 
 a spring arranged in series with the second actuator between the upper mount and the lower mount; 
 wherein the ball screw actuator and the hydraulic actuator are coaxial. 
 
     
     
       2. The suspension actuator according to  claim 1 , wherein the hydraulic actuator is operated by a pump located remotely from the suspension actuator. 
     
     
       3. The suspension actuator according to  claim 1 , wherein the second actuator requires less power to hold an output force than the first actuator. 
     
     
       4. The suspension actuator according to  claim 1 , further comprising a third actuator forming a third load path between the upper mount and the lower mount, the third load path being in parallel to the first load path and the second load path. 
     
     
       5. The suspension actuator according to  claim 4 , wherein the third actuator is one of a hydraulic actuator or an air spring actuator. 
     
     
       6. The suspension actuator according to  claim 1 ,
 wherein the hydraulic actuator is operated by a pump located remotely from the suspension actuator, the pump operating another hydraulic actuator of another suspension actuator; and 
 wherein the hydraulic actuator requires less power to hold an output force than the ball screw actuator. 
 
     
     
       7. The suspension actuator according to  claim 1 , wherein the hydraulic actuator surrounds the ball screw actuator. 
     
     
       8. The suspension actuator according to  claim 7 , wherein the hydraulic actuator includes a chamber that surrounds the ball screw actuator and is filled with a hydraulic fluid. 
     
     
       9. A suspension actuator comprising:
 a first mount for connecting to a sprung mass of a vehicle; 
 a second mount for connecting to an unsprung mass of the vehicle; and 
 a primary actuator for selectively applying a first force between the first mount and the second mount; 
 a spring; 
 a second actuator for selectively applying a second force between the first mount and the second mount in parallel to the primary actuator, the second actuator being a hydraulic spring seat arranged in series with the spring for selectively applying the second force between the first mount and the second mount and surrounding the primary actuator; 
 wherein the second actuator requires less power to produce an output force than the primary actuator. 
 
     
     
       10. The suspension actuator according to  claim 9 , wherein the second actuator has lower bandwidth than the primary actuator. 
     
     
       11. The suspension actuator according to  claim 10 , wherein the second actuator requires no power to sustain the output force. 
     
     
       12. The suspension actuator according to  claim 9 , wherein the primary actuator is a ball screw actuator. 
     
     
       13. The suspension actuator according to  claim 9 , wherein the second actuator includes a chamber that surrounds the primary actuator and is filled with a hydraulic fluid. 
     
     
       14. The suspension actuator according to  claim 13 , wherein the second actuator includes a piston within the chamber that is pressed by the hydraulic fluid to displace the spring. 
     
     
       15. The suspension actuator according to  claim 9 , wherein an annular structure is connected to the first mount to move therewith and a shaft is connected to the lower mount to move therewith;
 wherein the primary actuator is connected between the annular structure and the shaft such that the shaft reciprocates linearly within the annular structure; 
 wherein the second actuator includes a spring seat and extends around the annular structure. 
 
     
     
       16. The suspension actuator according to  claim 15 , wherein the second actuator includes a housing that is fixed relative to the first mount and defines a chamber that surrounds the annular structure, wherein the spring seat is a piston within the chamber. 
     
     
       17. A suspension system for a vehicle comprising:
 two suspension actuators, each suspension actuator configured to selectively apply force between a sprung mass of the vehicle and one of two unsprung masses of the vehicle, wherein each of the suspension actuators is associated with one of the unsprung masses and includes:
 an upper mount connectable to the sprung mass of the vehicle; 
 a lower mount connectable to the one of the two unsprung masses associated with the suspension actuator; 
 a primary actuator forming a first load path by applying force between the upper mount and the lower mount, the primary actuator being a ball screw actuator; 
 a second actuator forming a second load path in parallel with the first load path between the upper mount and the lower mount, the second actuator being a hydraulic actuator that includes a spring seat; and 
 a spring arranged in series with the second actuator between the upper mount and the lower mount; 
 wherein the ball screw actuator and the hydraulic actuator are coaxial; and 
 
 a fluid circuit comprising a pump in fluidic communication with the hydraulic actuator of the two of the suspension actuators to control displacement thereof. 
 
     
     
       18. The suspension system according to  claim 17 , wherein the fluid circuit transfers force between the hydraulic actuators of the two suspension actuators. 
     
     
       19. The suspension system according to  claim 17 , wherein the pump cannot cause simultaneous positive displacement of the hydraulic actuators of the two suspension actuators. 
     
     
       20. The suspension system according to  claim 17 , further comprising two additional ones of the suspension actuators configured to selectively apply force between the sprung mass of the vehicle and one of two additional unsprung masses of the vehicle associated therewith, and a second pump in fluidic communication with the hydraulic actuators of the two additional suspension actuators to control displacement thereof. 
     
     
       21. The suspension system according to  claim 20 , wherein the pump and the second pump control one of pitch or roll of the vehicle. 
     
     
       22. The suspension system according to  claim 20 , wherein the pump controls roll of the vehicle, and the second pump controls pitch of the vehicle. 
     
     
       23. The suspension system according to  claim 17 , wherein the hydraulic actuator displaces an upper end of the spring relative to the upper mount. 
     
     
       24. A suspension actuator comprising:
 an upper mount connectable to a sprung mass of a vehicle; 
 a lower mount connectable to an unsprung mass of the vehicle; 
 a first actuator forming a first load path between the upper mount and the lower mount, wherein the first actuator is one of an electromagnetic linear actuator or a ball screw actuator; 
 a second actuator forming a second load path in parallel with the first load path between the upper mount and the lower mount, wherein the second actuator is one of a mechanical linear actuator, an air spring actuator, or a hydraulic actuator; 
 a spring, wherein the hydraulic actuator acts in series with the spring between the upper mount and the lower mount; 
 a spring seat that presses against the spring, wherein the hydraulic actuator is configured to move the spring seat axially to apply force via the spring between the upper mount and the lower mount; and 
 an annular structure connected to the upper mount to move therewith and a shaft connected to the lower mount to move therewith; 
 wherein the ball screw actuator is connected between the annular structure and the shaft such that the shaft reciprocates linearly within the annular structure; 
 wherein the hydraulic actuator includes a housing that is fixed relative to the upper mount and defines a chamber that surrounds the annular structure, and the spring seat is a piston within the chamber and extends around the annular structure; and 
 wherein the second actuator requires less power to hold an output force than the first actuator. 
 
     
     
       25. The suspension actuator according to  claim 24 , wherein the housing includes a port through which the hydraulic actuator receives a hydraulic fluid from a fluid source into the chamber to change displacement of the spring seat relative to the upper mount.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/562,626, filed Sep. 25, 2017, the entire disclosure of which is incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to suspension systems for vehicles and, in particular, active suspension actuators and suspension systems with active suspension actuators. 
     BACKGROUND 
     Conventional vehicle suspension systems are passive systems having a spring and a damper that transfer and damp forces between the sprung mass (e.g., vehicle body) and the unsprung mass (e.g., tires, wheels, brakes, etc.). Handling characteristics of the vehicle and passenger comfort may be improved with an active suspension system that selectively controls force transfer to the vehicle body. 
     SUMMARY 
     Disclosed herein are implementations of active suspension systems and suspension actuators. In one implementation, a suspension actuator includes an upper mount, a lower mount, a first actuator, and a second actuator. The upper mount is connectable to a sprung mass of a vehicle. The lower mount is connectable to an unsprung mass of the vehicle. The first actuator forms a first load path between the upper mount and the lower mount. The first actuator is one of an electromagnetic linear actuator or a ball screw actuator. The second actuator forms a second load path in parallel with the first load path between the upper mount and the lower mount. The second actuator is one of a mechanical linear actuator, an air spring actuator, or a hydraulic actuator. 
     In another implementation, a suspension actuator includes a first mount, a second mount, a primary actuator, and a second actuator. The first mount is for connecting to a sprung mass of a vehicle. The second mount is for connecting to an unsprung mass of the vehicle. The primary actuator selectively applies force between the first mount and the second mount. The second actuator selectively applies force between the first mount and the second mount in parallel to the primary actuator. The second actuator requires less power to produce an output force than the primary actuator. 
     A suspension system for a vehicle includes four suspension actuators and a fluid circuit. Each suspension actuator is configured to selectively apply force between a sprung mass of a vehicle and one of four unsprung masses of the vehicle. Each suspension actuator includes a primary actuator and a hydraulic actuator mechanism. The primary actuators are for selectively applying force between the sprung mass and one of the unsprung masses. The hydraulic actuator mechanism is for selectively applying force between the sprung mass and the one of the unsprung masses in parallel with the primary actuator. The fluid circuit includes a pump in fluidic communication with the hydraulic actuator mechanism of two of the suspension actuators to control displacement thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a vehicle. 
         FIG. 2  is a view of a suspension assembly of the vehicle in  FIG. 1 . 
         FIG. 3A  is a schematic view of an embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 3B  is a schematic view of another embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 3C  is a schematic view of another embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 4  is a plot of force vs. velocity illustrating operating envelopes of actuator mechanisms for use in the suspension actuators of  FIGS. 3A-3C . 
         FIG. 5  is a cross-sectional view of an embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 6  is a cross-sectional view of another embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 7A  is a cross-sectional view of another embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 7B  is a cross-sectional view of a variation of the suspension actuator of  FIG. 7A . 
         FIG. 8  is a cross-sectional view of another embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 9  is a cross-sectional view of another embodiment of a suspension actuator for use in the suspension assembly of  FIG. 1 . 
         FIG. 10  is a schematic view of a hydraulic circuit including the suspension actuator of  FIG. 9  and an embodiment of a pump actuator. 
         FIG. 11  is a schematic view of another hydraulic circuit including the suspension actuator of  FIG. 9  and another embodiment of a pump actuator. 
         FIG. 12  is a schematic view of another hydraulic circuit including two of the suspension actuators of  FIG. 9  and another embodiment of a pump actuator. 
         FIG. 13  is a schematic view of another hydraulic circuit including four of the suspension actuators of  FIG. 9   
         FIG. 14  is a schematic view of another hydraulic circuit including four of the suspension actuators of  FIG. 9   
         FIG. 15  is a schematic view of another hydraulic circuit including four of the suspension actuators of  FIG. 9   
         FIG. 16  is a schematic view of another hydraulic circuit including four of the suspension actuators of  FIG. 9   
         FIG. 17  is a schematic view of another hydraulic circuit including four of the suspension actuators of  FIG. 9   
         FIG. 18  is a schematic view of another hydraulic circuit including four of the suspension actuators of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a vehicle  100  generally includes a vehicle body  110 , a control system  120 , an energy storage system  130 , a drive system  140 , a steering system  150 , and a suspension system  160 . The drive system  140 , the steering system  150 , and the suspension system  160  are connected to the vehicle body  110  to, respectively, propel, steer, and support the vehicle  100  on a road surface. The control system  120  controls operation of the energy storage system  130 , the drive system  140 , the steering system  150 , and the suspension system  160 . The energy storage system  130  provides electrical power to the control system  120 , the drive system  140 , the steering system  150 , and the suspension system  160  for operation thereof. 
     Referring to  FIG. 2 , the suspension system  160  is generally configured to maintain contact with the road surface and to control movement of the vehicle body  110  as the vehicle  100  travels over disturbances in the road. The suspension system  160  includes one or more suspension assemblies  262 , for example, one at each corner of the vehicle  100  (e.g., front left, front right, rear right, and rear left) to support the vehicle  100  on the road surface. 
     Each suspension assembly  262  generally includes a tire and wheel assembly  264 , a steering knuckle  266 , a suspension arm  268 , and a suspension actuator  270 . The tire and wheel assembly  264  and, specifically a tire thereof, contacts the road surface. The tire and wheel assembly  264  is rotatably coupled to the steering knuckle  266 , which is in turn pivotably coupled to the suspension arm  268 . The suspension arm  268  extends inboard the steering knuckle  266  to be pivotably coupled to the vehicle body  110 , thereby allowing the tire and wheel assembly  264  to move vertically relative to the vehicle body  110 . The suspension actuator  270  is coupled to and extends between the vehicle body  110  and the suspension arm  268  to control the vertical movement between the tire and wheel assembly  264  and the vehicle body  110 . The tire and wheel assembly  264 , the steering knuckle  266 , and the suspension arm  268  may be considered part of an unsprung mass, while the vehicle body  110  forms a sprung mass. On a vehicle having four wheels, the vehicle may be considered to have four unsprung masses. 
     The suspension actuator  270  is actively operable to control movement of the unsprung mass relative to the sprung mass, including both to cause and resist movement of the suspension arm  268  relative to the vehicle body  110 . More particularly, referring to the schematic view of  FIG. 3 , the suspension actuator  270  includes multiple actuator mechanisms, which act in parallel to each other to apply force (e.g., selectively or controllably) between the sprung mass  310  (e.g., the vehicle body) and the unsprung mass  360  (e.g., the suspension arm  268 , among other components). By acting in parallel, the total force applied by the suspension actuator  270  between the sprung mass  310  and the unsprung mass  360  is the sum of the forces applied by the actuator mechanisms. The suspension actuator  270 , by including multiple actuator mechanisms, may be referred to as a multi-element actuator, a multi-stage suspension actuator, or a suspension actuator assembly (or actuator assembly). Furthermore, the various actuator mechanisms discussed herein may be referred to as actuators. 
     Referring to the schematic views of  FIGS. 3A-3C , the multiple actuation mechanisms of the suspension actuator  270  act in parallel between the vehicle body  110  and the suspension arm  268 . The suspension actuator  270  may include different numbers of actuation mechanisms, which may have different properties and be of different types. The suspension actuator  270  includes two actuator mechanisms, including a first actuation mechanism  372  and a second actuation mechanism  374 , while an alternative suspension actuator  270 ′ additionally includes a third actuation mechanism  376 , and a still further alternative suspension actuator  270 ″ includes a still further fourth actuation mechanism  378 . The different properties of the actuation mechanisms may include force vs. velocity characteristics, mechanical advantage, force hold energy consumption, and energy regeneration capability. Force vs. velocity characteristics refer to the force output capacity for velocity (positive and negative) between ends of the actuator mechanism. Force vs. velocity envelopes for the actuator mechanism are illustrated in  FIG. 4 . Force hold energy consumption (e.g., power hold) refers to the rate of energy consumption by the actuation mechanism to sustain a force output. Energy regeneration refers to the ability of the actuation mechanism to generate electrical energy from force applied thereto. The different actuation mechanisms may, for example, electromagnetic linear actuators, lead screw actuators ball screw actuators, air spring actuators, and hydraulic actuators, which will be discussed in further detail below with respect to specific embodiments of the suspension actuator  270 . Lead screw actuators and ball screw actuators may be referred to as mechanical linear actuator mechanisms. 
     The first actuator mechanism  372  provides force output for primary ride control of road disturbances, to control force transfer from road disturbances to the vehicle body  110  (e.g., to provide passenger comfort) and to maintain contact of the tire and wheel assembly  264  with the road surface (e.g., to maintain friction contact for drive, braking, and steering control). Controlling primary ride requires the first actuator mechanism to operate at a relatively high frequency (e.g., around 2 Hz) and at relatively high forces. As such, the first actuator mechanism  372  is high velocity, high force actuation mechanism, which is capable of producing high force output at high velocities to cause and resist movement between the sprung mass  310  and the unsprung mass  360 . The first actuator mechanism  372  is capable of producing force within an area of a first operating envelope  472  illustrated in  FIG. 4 . The first actuator mechanism  372  may be considered a high bandwidth actuator. 
     The first actuator mechanism  372  has high power hold, and energy regeneration capability. 
     The first actuator mechanism  372  may, for example, be an electromagnetic linear actuator (e.g., a voice coil; see suspension actuator  570  shown in  FIG. 5 ) or a ball screw actuator (see suspension actuator  670  shown in  FIG. 6 ). 
     The second actuator mechanism  374  provides sustained force output between the sprung mass  310  and the unsprung mass  360 . For example, when the vehicle  100  is at rest, the second actuator mechanism  374  may provide the only output force from the suspension actuator  270  for supporting the vehicle  100  (e.g., the first actuator mechanism  372  produces no output force). When the vehicle  100  is moving, the second actuator mechanism  374  may sustain an output force, so as to provide a ride height of the vehicle  100 , to resist a tendency of the vehicle  100  to roll (e.g., lean outward about a roll axis as the vehicle  100  travels around a corner), or to resist a tendency of the vehicle  100  to pitch (e.g., dive forward during deceleration or squat rearward during acceleration). The second actuator mechanism  374  is a low velocity, high force actuation mechanism, which is capable of producing high force output up to low velocities to cause and resist movement between the sprung mass  310  and the unsprung mass  360 . The second actuator mechanism  374  may, for example, be capable of output force at higher magnitudes than the first actuator mechanism  372 . The second actuator mechanism  374  is capable of outputting force within an area of the second operating envelope  474  illustrated in  FIG. 4 . The second actuator mechanism  374  may be considered a low bandwidth actuator (e.g., lower bandwidth relative to the high bandwidth of the first actuator mechanism  374 ). 
     The second actuator mechanism  374  may also be arranged to apply force between the sprung mass  310  and the unsprung mass  360  in conjunction with spring  374   a . For example, the second actuator mechanism  374  may be arranged in series with the spring  374   a  between the sprung mass  310  and the unsprung mass  360 . In the case of the second actuator mechanism  374  being an air spring, the spring  374   a  is considered incorporated into and formed by the second actuator mechanism  374 . By moving to apply force to the spring  374   a , the second actuator mechanism  374  may be referred to as a spring seat actuator. 
     The second actuator mechanism  374  may have high mechanical advantage as compared to the first actuator mechanism  372 , such the second actuator mechanism  374  may require a comparatively low input force to achieve a given output force. The second actuator mechanism  374  may have low power hold as compared to the first actuator mechanism  372 , such that the second actuator mechanism  374  consumes comparatively less energy (e.g., none) to maintain a given force output between the sprung mass  310  and the unsprung mass  360 . The second actuator mechanism  374  may, depending on type, provide regeneration. 
     The second actuator mechanism  374  may, for example, be a lead screw actuator (see the suspension actuator  570  in  FIG. 5 ), a ball screw actuator (see the suspension actuator  670  in  FIG. 6 ), an air spring (see suspension actuator  770  in  FIG. 7A ), or a hydraulic actuator (see suspension actuator  970  in  FIG. 9 ). 
     Referring to the suspension actuator  270 ′ in  FIG. 3B , the third actuator mechanism  376  may be configured in different manners to supplement the output forces applied by the first actuator mechanism  372  and the second actuator mechanism  374 . 
     In one example, the third actuator mechanism  376  provides velocity dependent force only to resist, but not cause, motion between the sprung mass  310  and the unsprung mass  360 . In this example, the third actuator mechanism  376  applies increasing magnitude force between the sprung mass  310  and the unsprung mass  360  with increasing speed therebetween. The third actuator mechanism  376  provides no output force at zero velocity, and high output force at high velocities. The third actuator mechanism  376  is capable of outputting force in quadrants  2  and  4 , but not quadrants  1  and  3 , within the operating envelope  476   a . The third actuator mechanism  376  may provide high output force, which is velocity dependent, with little to no energy input, and has a zero-power hold, but does not provide regeneration. In this first example, the third actuator mechanism  376  may, for example, be a hydraulic damper controlled by a throttling valve (see suspension actuator  770  in  FIG. 7A ). 
     In a second example, the third actuator mechanism  376  is a high velocity, high force actuation mechanism, which is capable of producing high force output at high velocities to cause and resist movement between the sprung mass  310  and the unsprung mass  360 . The third actuator mechanism  376  may, for example, be capable of output force at magnitudes higher or lower (as shown) than the first actuator mechanism  372 . In this example, the third actuator mechanism  376  may have high mechanical advantage as compared to the first actuator mechanism  372 , such the third actuator mechanism  376  requires a comparatively low input force to achieve a given output force. The third actuator mechanism  376  have low, but non-zero, power hold as compared to the first actuator mechanism  372 , such that the second actuator mechanism  374  consumes comparatively less energy to maintain a given force output between the sprung mass  310  and the unsprung mass  360 . The third actuator mechanism  376  provides regeneration. In this other example, the third actuator mechanism  376  may be a hydraulic damper controlled by a pump (see suspension actuator  870  in  FIG. 8 ). 
     Referring to the suspension actuator  270 ″ in  FIG. 3C , the third actuator mechanism  376  may be configured as the first example described above, while the fourth actuator mechanism  378  is configured as the second example of the third actuator mechanism  376  described above. The third actuator mechanism  376  may, for example, be a hydraulic damper controlled by a throttling valve, while the fourth actuator mechanism  378  may be the same hydraulic damper further controlled by a pump (see the suspension actuator  870  in in  FIG. 8 ). 
     In  FIG. 5 , the suspension actuator  570  is a two-element actuator that includes an electromagnetic linear actuator mechanism  572  and a lead screw actuator mechanism  574 . The electromagnetic linear actuator mechanism  572  and the lead screw actuator mechanism  574  function similar to the first actuator mechanism  372  and the second actuator mechanism  374 , respectively, of the suspension actuator  270 . More particularly, the electromagnetic linear actuator mechanism  572  is the primary actuator for controlling primary ride with road disturbances, while the lead screw actuator mechanism  574  provides a sustained force output. 
     The suspension actuator  570  includes an upper mount  580  and a lower mount  582  by which the suspension actuator  570  is couple able to the sprung mass  310  and the unsprung mass  360 . The electromagnetic linear actuator mechanism  572  forms a first load path between the upper mount  580  and the lower mount  582 . The lead screw actuator mechanism  574  is arranged in series with a spring  574   a  to form a second load path, parallel with the first load path, between the upper mount  580  and the lower mount  582 . The lead screw actuator mechanism  574  is operable to move a spring seat member  584  axially relative to the upper mount  580  and to increase or decrease the force applied by the between the sprung mass  310  and the unsprung mass  360  to hold or move the position of the spring seat member  584  (e.g., to counter roll or pitch of the vehicle  100 ). By changing displacement of the spring seat member  584 , the lead screw actuator mechanism  574  may be referred to as a spring seat actuator. 
     The suspension actuator  570 , for example, includes an annular structure  586  connected to the upper mount  580  to move therewith and a shaft  588  connected to the lower mount  582  to move therewith. The electromagnetic linear actuator mechanism  572  is formed between annular structure  586  and the shaft  588 , such that the shaft  588  reciprocates linearly within the annular structure. The electromagnetic linear actuator mechanism  572  includes an outer coil  572   a  fixed to an inner portion of the annular structure  586  and an inner magnet  572   b  fixed to an outer portion of the shaft  588 . As current is applied to the outer coil  572   a , a magnetic field is generated that passes through the inner magnet  572   b  to apply axial force to the shaft  588 . 
     The lead screw actuator mechanism  574  is formed between the annular structure  586  and the spring seat member  584 . The lead screw actuator mechanism  574  includes a stator  574   b  and a rotor  574   c  that form an electric motor. The stator  574   b  is fixed to an outer portion of the annular structure  586 , while the rotor  574   c  is positioned radially outward thereof and is rotated thereby. The rotor  574   c  threadably engages the spring seat member  584 , such that rotation of the rotor  574   c  moves the spring seat member  584  toward or away from the upper mount  580 . For example, the rotor  574   c  includes an outer threaded member  574   d  coupled thereto and extending radially outward thereof, which engages an inner threaded portion  584   a  of the spring seat member  584 . Furthermore, when the electromagnetic linear actuator mechanism  572  is operated, the shaft  588  may be received axially by the lead screw actuator mechanism  574 . 
     The lower mount  582  and the spring seat member  584  may cooperatively define a housing, which contain both the electromagnetic linear actuator mechanism  572  and the lead screw actuator mechanism  574 . Furthermore, while the lower mount  582  engages the spring  574   a  to form a lower spring seat, one or more intermediate structures may be arranged between the spring  574   a  and the lower mount  582 . 
     Referring to  FIG. 6 , the suspension actuator  670  is a two-element actuator that includes a first ball screw actuator mechanism  672  and a second ball screw actuator mechanism  674 . The first ball screw actuator mechanism  672  and the second ball screw actuator mechanism  674  function similar to the first actuator mechanism  372  and the second actuator mechanism  374 , respectively, of the suspension actuator  270 . More particularly, the first ball screw actuator mechanism  672  is the primary actuator for controlling primary ride with road disturbances, while the second ball screw actuator mechanism  674  provides a sustained force output. The second ball screw actuator mechanism  674  may have greater mechanical advantage than the first ball screw actuator mechanism  672 , for example, by having a lower thread pitch. The first ball screw actuator mechanism  672  and the second ball screw actuator mechanism  674  are both capable of regeneration. 
     The suspension actuator  670  includes an upper mount  680  and a lower mount  682  by which the suspension actuator  670  is coupleable to the sprung mass  310  and the unsprung mass  360 . The first ball screw actuator mechanism  672  forms a first load path between the upper mount  680  and the lower mount  682 . The second ball screw actuator mechanism  674  is arranged in series with a spring  674   a  to form a second load path, parallel with the first load path, between the upper mount  680  and the lower mount  682 . The second ball screw actuator mechanism  674  is operable to move a spring seat member  684 , axially relative to the upper mount  680  and to increase or decrease the force applied between the sprung mass  310  and the unsprung mass  360  to hold or move the position of the spring seat member  684 . 
     The suspension actuator  670 , for example, includes an annular structure  686  connected to the upper mount  680  to move therewith and a shaft  688  connected to the lower mount  682  to move therewith. The first ball screw actuator mechanism  672  is connected between annular structure  686  and the shaft  688 , such that the shaft  688  reciprocates linearly within the annular structure  686 . The first ball screw actuator mechanism  672  includes an electric motor having an outer stator  672   a  fixed to an inner portion of the annular structure  686  and a rotor  672   b  fixed to a ball nut  672   c  (e.g., having recirculating balls not shown), which is in turn operably engaged with the shaft  688 . As current is applied to the outer stator  672   a , the rotor  672   b  and, thereby, the ball nut  672   c  are rotated. As a result, torque is applied to the ball nut  672   c , which applies axial force between the annular structure  686  and the shaft  688 . The first ball screw actuator mechanism  672   
     The second ball screw actuator mechanism  674  is connected between the annular structure  686  and the spring seat member  684 . The second ball screw actuator mechanism  674  includes a stator  674   b  and a rotor  674   c  that form an electric motor. The stator  674   b  is fixed to an outer portion of the spring seat member  684 , while the rotor  674   c  is positioned radially inward thereof and is rotated thereby. The rotor  674   c  rotates another ball nut  674   d , which is in turn operably engaged with the annular structure  686  (e.g., functioning as a shaft). As current is applied to the stator  674   b , the rotor  674   c  and, thereby, the ball nut  674   d  are rotated. As a result, torque is applied to the ball nut  674   d , which applies axial force between the annular structure  686  and the spring seat member  684 , so as change or hold the position of the spring seat member  684  relative to the sprung mass  310 . By changing displacement of the spring seat member  684 , the second ball screw actuator mechanism  674  may be referred to as a spring seat actuator. 
     Alternatively, a lead screw actuator mechanism, such as the lead screw actuator mechanism  574 , may be used instead of the second ball screw actuator mechanism  674 , and in combination with the first ball screw actuator mechanism  672 . As another alternative, a hydraulic actuator mechanism may be used instead of the second ball screw actuator mechanism  674  (see suspension actuator  970  in  FIG. 9 ). In still further variations, the second ball screw actuator mechanism  674  may include a brake (e.g., a mechanical brake that prevents rotation of the rotor  674   c ) that provides the second ball screw actuator mechanism  674  with low or no power hold. In still further variation, the second ball screw actuator mechanism  674  may be operated by a motor that is not coaxial with the first ball screw actuator mechanism  672 . For example, the motor may be laterally offset and parallel to the shaft  688  being operably coupled to the ball nut  674   d , for example, with an intermediate gear. 
     A variation of the suspension actuator  670  may further include an air spring actuator mechanism arranged in parallel with the first ball screw actuator  672  and the second ball screw actuator  674 . For example, the air spring actuator mechanism may include an air chamber generally concentric with the annular structure  686  and configured to apply force between the upper mount  680  and the spring seat member  684 . 
     In  FIG. 7A , the suspension actuator  770  is a three-element actuator that includes an electromagnetic linear actuator mechanism  772 , an air spring actuator mechanism  774 , and a hydraulic actuator mechanism  776 . The electromagnetic linear actuator mechanism  772 , the air spring actuator mechanism  774 , and the hydraulic actuator mechanism  776  function similar to the first actuator mechanism  372 , the second actuator mechanism  374 , and the third actuator mechanism, respectively of the suspension actuator  270 ′. More particularly, the electromagnetic linear actuator mechanism  772  is the primary actuator for controlling primary ride with road disturbances, while the air spring actuator mechanism  774  provides a sustained force output, and the hydraulic actuator mechanism  776  provides additional velocity dependent resistance, and low power hold. The electromagnetic linear actuator mechanism  772 , the air spring actuator mechanism  774 , and the hydraulic actuator mechanism  776  apply force between the sprung mass  310  and the unsprung mass  360  in parallel. 
     The electromagnetic linear actuator mechanism  772  is configured substantially similar to the electromagnetic linear actuator mechanism  572  described previously. The electromagnetic linear actuator mechanism  772  generally includes a shaft  778 , a magnet  772   a  coupled to the shaft  778 , and a coil  772   b  coupled to a housing  780 . A lower end of the shaft  778  is configured to couple to the unsprung mass  360 , such as with a lower mount  782 . Alternatively, the electromagnetic linear actuator mechanism  772  may be replaced with a ball screw actuator mechanism, such as the first ball screw actuator mechanism  672 . 
     The air spring actuator mechanism  774  generally includes the housing  780 , which is rigid and defines a chamber  780   a  therein. The air spring actuator mechanism  774  further includes a piston or plate member  774   a  and a membrane  774   b  that couples the plate member  774   a  to the housing  780 . The plate member  774   a  is connected to an upper end of the shaft  778 . An air source (not labeled) is in fluidic communication with the chamber  780   a  via a port  780   b  to provide compressed air thereto. As air is added to or removed from the chamber  780   a , the distance between the sprung mass  310  and the unsprung mass  360  is increased or decreased, respectively. As pressure increases or decreases in the chamber  780   a , greater or less force is applied to the plate member  774   a , so as to apply greater or lesser force to the shaft  778 . 
     The hydraulic actuator mechanism  776  includes a cylinder  776   a , a piston  776   b , and a throttling valve  776   c . The piston  776   b  is coupled to the shaft  778  of the electromagnetic linear actuator mechanism  772  and/or to the plate member  774   a  of the air spring actuator mechanism  774 . The piston  776   b  moves within the cylinder  776   a  that is coupled to the housing  780 , such that force may be transferred from the cylinder  776   a  to the housing  780  and, ultimately, the sprung mass  310 . The cylinder  776   a  contains fluid on each side of the piston  776   b . The throttling valve  776   c  selectively allows communication of the fluid between each side of the piston  776   b  as the piston  776   b  moves. The hydraulic actuator mechanism  776 , thereby, functions as an adjustable output hydraulic damper that applies variable, velocity-dependent force dependent. 
     Referring to  FIG. 7B , a suspension actuator  770 ′ is a variation of the suspension actuator  770 , which includes a hydraulic actuator mechanism  776 ′ having a pump  776   d  instead of the throttling valve  776   c . The pump  776   d  may provide regeneration but requires power for holding the piston  776   b  in a position within the cylinder  776   a.    
     In a still further variation, a suspension actuator assembly may include both the hydraulic actuator mechanism  776  (i.e., having the throttling valve  776   c ) and the hydraulic actuator mechanism  776 ′ (i.e., having the pump  776   d ), which act in parallel to each other (see the suspension actuator  270 ″ in  FIG. 3B ). 
       FIG. 8 , a suspension actuator  870  includes a hydraulic actuator  872 , an electromagnetic linear actuator  874 , and an air spring actuator  876 . The hydraulic actuator  872  generally includes a cylinder  872   a  and a piston  872   b  movable within the cylinder  872   a . The piston  872   b  is in turn coupled to a shaft  888  that is connectable to the unsprung mass  360  (e.g., via a lower mount  882 ). The piston  872   b  forms an intermediate chamber  872   c  and a lower chamber  872   d  within the cylinder  872   a , and a pump  886  controls flow of a fixed volume of fluid therebetween (as indicated by a dashed arrow). As fluid is moved into the intermediate chamber  872   c , the piston  872   b  is biased downward. 
     The electromagnetic linear actuator  874  is arranged in parallel with the hydraulic actuator  872  to apply force between the sprung mass  310  and the unsprung mass  360 . The electromagnetic linear actuator  874  includes another piston  874   a , which forms the upper end of the intermediate chamber  872   c  and further defines an upper chamber  872   e  in the cylinder  872   a . The piston  874   a  includes a magnet, while a coil  874   b  is arranged around the cylinder  872   a . A spring  874   c  is arranged between an upper end of the of the suspension actuator  870  (e.g., an upper mount  890  thereof). As current is sent to the coil  874   b , the coil  874   b  generates a magnetic field that moves the piston  874   a  axially, which acts on the fluid in the intermediate chamber  872   c  and, if fixed or restricted in volume by the pump  886 , causes the piston  872   b  to move and, thereby, the fluid to flow between the upper chamber  872   e  in fluidic communication with the lower chamber  872   d.    
     The air spring actuator  876  is arranged in parallel with the hydraulic actuator  872  and the electromagnetic linear actuator  874 . The air spring actuator  876  is configured similar to the air spring actuator mechanism  774  described with respect to  FIG. 7 . The air spring actuator  876  includes a chamber  880   a , which receives compressed air, and a piston  876   a  (e.g., plate member) that is movably coupled to an outer housing  880  and is fixedly connected to the shaft  888  and the piston  872   b . As air is added to or removed from the chamber  780   a , the distance between the sprung mass  310  and the unsprung mass  360  is increased or decreased, respectively. As pressure is increased in the chamber  880   a , the pressure forces the shaft  888  downward. The chamber  880   a  is defined between the outer housing  880  and an inner housing  884 , which may contain the hydraulic actuator  872  and the electromagnetic linear actuator  874 . Air is supplied to the chamber  880   a  via a port  880   b  in the outer housing  880 . 
     Referring to  FIG. 9 , a suspension actuator  970  is configured substantially similar to the suspension actuator  670 , but rather than including the second ball screw actuator mechanism  674 , the suspension actuator  970  includes a hydraulic actuator mechanism  974 , which functions as a high force, low velocity actuator. The hydraulic actuator mechanism  974  acts in series with the spring  674   a  between the sprung mass  310  and the unsprung mass  360 . The suspension actuator  970  includes the first ball screw actuator mechanism  672 , which acts in parallel to the hydraulic actuator mechanism  974  between the sprung mass  310  and the unsprung mass  360 , along with various other components described with respect to the suspension actuator  670  in  FIG. 6 . Alternatively, the suspension actuator  970  may include the magnetic linear actuator  572 , or another high force, high velocity linear actuator. By using the hydraulic actuator mechanism  974  in combination with the linear actuator  672 , or the linear actuator  572 , the suspension actuator  970  may output force for sustained loading (e.g., turns and braking events), which reduces the required force output and energy consumption otherwise required of the linear actuator  672  for certain ride control (e.g., limiting roll during turns, and limiting pitch during braking events). The suspension actuator  970  may also be referred to as a suspension actuator assembly, while the hydraulic actuator mechanism  974  may be referred to as a hydraulic actuator or hydraulic spring seat. 
     The hydraulic actuator mechanism  974  is configured to move a spring seat  984  axially, so as to apply force via the spring  674   a  between the sprung mass  310  and the unsprung mass  360 , for example, to change a height of the vehicle  100  (i.e., a distance between the sprung mass  310  and the unsprung mass  360 ) to control roll of the vehicle  100  and/or to control pitch of the vehicle  100 . The hydraulic actuator mechanism  974  generally includes a housing  974   a  that is fixed axially relative to an upper end (e.g., an upper mount  680 ) of the suspension actuator  970 . The housing  974   a  defines a chamber  974   b  (e.g., cylinder or cylindrical chamber) that surrounds the annular structure  686 . The spring seat  984  is arranged as a piston within the chamber  974   b . The housing  974   a  includes a port  974   c  through which the hydraulic actuator mechanism  974  receives a hydraulic fluid, which is generally non-compressible, from a fluid source. The hydraulic fluid fills the chamber  974   b  to press the spring seat  984  against the spring  674   a , whereby a position of the spring seat  984  may be changed relative to the sprung mass  310  and the force applied to the spring  674   a  may be varied (e.g., as loading changes, such as during roll and pitch events). By changing displacement of the spring seat  984 , the hydraulic actuator mechanism  974  may be referred to as a spring seat actuator. While the hydraulic actuator mechanism  974  is generally coaxial with (e.g., surrounds) the ball screw actuator mechanism  672  and provides packaging advantages thereby, other configurations are contemplated (e.g., being laterally offset). 
     Referring to  FIG. 10 , the suspension actuator  970  is depicted schematically with the ball screw actuator mechanism  672  acting in parallel with the hydraulic actuator mechanism  974  between the sprung mass  310  and the unsprung mass  360 . The hydraulic actuator mechanism  974  is in fluidic communication with a hydraulic circuit  1080  that includes one or more flow control devices, which are interconnected with (e.g., via conduits) and control the volume of the fluid in the chamber  974   b . The hydraulic circuit  1080  may include one or more of a pump  1082 , an isolation valve  1084 , and an accumulator  1086 . The pump  1082  is configured to selectively change the amount of fluid in the chamber  974   b  of the hydraulic actuator mechanism  974  to change displacement thereof. The pump  1082  may also increase or decrease fluid pressure within the hydraulic circuit  1080  to, thereby, apply greater or lesser force to the spring  674   a  via the spring seat  984  (e.g., during long duration loading events, such as cornering or braking). The pump  1082  may, for example, be configured as a hydraulic cylinder (e.g., master cylinder device), which includes a cylinder  1082   a  defining a fluid chamber and a piston  1082   b  therein. The piston  1082   b  is selectively movable within the cylinder  1082   a  by an actuator  1082   c , so as to provide more or less fluid to the suspension actuator  970 . As the amount of the fluid is changed, the volume of the chamber  974   b  of the hydraulic actuator mechanism  974  changes and, thereby, displacement of the spring seat  984 . The actuator  1082   c  may also apply varying force to the piston  1082   b  so as to vary pressure within the hydraulic circuit  1080  to hold or change the position of the spring seat  984  as loading of the suspension actuator  1070  changes (e.g., due to roll and/or pitch vehicle events). The actuator  1082   c  may, for example, be a ball screw actuator (e.g., having a motor that rotates a ball nut to displace a shaft coupled to the piston  1082   b ). The pump  1082  may additionally include a stability spring  1082   d , which applies passive force to the piston  1082   b  to prevent free movement of the piston  1082   b  upon failure or loss of power to the actuator  1082   c . During normal operation, the force of the stability spring  1082   d  would need to be overcome by the actuator  1082   c  to vary and/or hold the position of the spring seat  984 . The hydraulic circuit  1080  and other hydraulic circuits disclosed herein may also be referred to as hydraulic systems. 
     The isolation valve  1084  is arranged in the hydraulic circuit  1080  between the pump  1082  and the hydraulic actuator mechanism  974  of the suspension actuator  970 . The isolation valve  1084  is selectively operable (e.g., may be closed) to hold the volume of the hydraulic circuit  1080  to maintain pressure within the hydraulic actuator mechanism  974  and, thereby, force against the spring  674   a . The isolation valve  1084 , thereby, provides for zero power hold of the hydraulic actuator mechanism  974 . 
     The accumulator  1086  is arranged in the hydraulic circuit  1080  between the hydraulic actuator mechanism  974  and the isolation valve  1084 , which provides compliance in the hydraulic circuit  1080 . The accumulator  1086  may, for example, be a compressed gas accumulator or a mechanical spring accumulator. The accumulator  1086  may be selectively operated, for example, by having another isolation valve  1086   a  that selectively isolates the accumulator  1086  from the hydraulic circuit  1080 . 
     As discussed in further detail below, various components of the hydraulic circuit  1080  (e.g., the stability spring  1082   d , the isolation valve  1084 , and the accumulator  1086 ) may be used on other configurations of hydraulic circuits. 
     Referring to  FIG. 11 , a hydraulic circuit  1180  is in communication with the hydraulic actuator mechanisms  974  of two of the suspension actuators  970 , so as to transfer loading therebetween. The suspension actuators  970  are each associated with one of two unsprung masses  360  of the vehicle  100 . By transferring loading therebetween, the hydraulic actuator mechanisms  974  (or the suspension actuators  970 ) may be considered hydraulically coupled or hydraulically linked. Such an arrangement may be advantageous in scenarios where force transfer and/or relative displacement between two suspension actuators  970  is desirable, such as to control roll and pitch of the vehicle  100 , which are the vehicle tilting side-to-side and front-to-back, respectively, during turning or acceleration events. Roll of the vehicle  100  may be controlled with the suspension actuators  970  on left and right sides at each end of the vehicle  100  being interconnected by the hydraulic circuit  1180 . Pitch of the vehicle  100  may be controlled with the suspension actuators  970  at front and rear ends on each side of the vehicle being interconnected by the hydraulic circuit  1180 . 
     The hydraulic circuit  1180  includes two pump units  1082  (i.e., pump units  1081 - 1 ,  10882 - 2 ), which are in fluidic communication with the hydraulic actuator mechanisms  974  of the first pump unit  1082 - 1  and the second pump unit  1082 - 2  with fixed volumes of fluid in closed circuits. The pump units  1082 - 1 ,  1082 - 2  are configured to selectively and independently control the volume in the chambers  974   b  of each of the hydraulic actuator mechanisms  974  of the two suspension actuators  970 - 1 ,  970 - 2 . The two pump units  1082 - 1 ,  1082 - 2  are also configured to transfer an additional fluid therebetween and, thereby, transfer force between the hydraulic actuator mechanism  974  of the two suspension actuators  970 - 1 ,  970 - 2 . More particularly, while one side of each of the cylinders  1082   a  (e.g., a load side) is in fluid communication with the hydraulic actuator mechanism  974  associated therewith, the other side of each of the cylinders  1082   a  (e.g., a return side) are in fluid communication with each other, such as by an intermediate conduit extending therebetween. Thus, as the piston  1082   b  of one of the pump units  1082 - 1  moves in one direction and presses the fluid in the conduit, such fluid travels through the conduit and presses against the piston  1082   b  of the other pump units  1082 - 2  in the opposite direction. 
     The pump units  1082  (e.g., the return side of the cylinders  1082   a ) are additionally in communication with an accumulator  1182   f . The accumulator  1182   f  provides compliance between the pump units  1082 , so as to allow independent motion therebetween. The two actuators  1082   c  of the pump units  1082 - 1 ,  1082 - 2  may be operated in unison (e.g., in the same direction and same magnitude to maintain displacement therebetween), which provides generally equal and opposite displacement of the hydraulic actuator mechanisms  974  (e.g., for controlling roll or pitch). The two actuators  1082   c  of the pump units  1082 - 1 ,  1082 - b  may also be operated out of unison (e.g., in different directions and/or different magnitudes causing relative displacement therebetween), which provides unequal displacement of the hydraulic actuator mechanisms  974 , which is permitted by the compliance afforded by the accumulator  1182   f . Because of the relative displacement between the two pistons  1182   b.    
     Alternatively, the actuators  1182   c  may be configured to move only in unison, in which case the accumulator  1182   f  may be selectively isolated (e.g., with a valve) or may be omitted. 
     Referring to  FIG. 12 , a hydraulic circuit  1280  is in communication with the hydraulic actuator mechanisms  974  of two of the suspension actuators  970  (i.e., a first suspension actuator  970 - 1  and a second suspension actuator  970 - 2 ). The hydraulic circuit  1280  includes a fixed volume of fluid and a pump unit  1282  arranged between the hydraulic actuator mechanisms  974  of the suspension actuators  970 - 1 ,  970 - 2  in a closed circuit. The pump unit  1282  is configured to provide opposite outputs to each of the two hydraulic actuator mechanisms  974 , thereby transferring force between the two hydraulic actuator mechanisms  974 . For example, the pump unit  1282  is configured as a hydraulic cylinder that includes a cylinder  1282   a  and a piston  1282   b  therein, which divides the cylinder  1282   a  into two chambers  1282   c  that are each in communication with one of the hydraulic actuator mechanisms  974  of the two suspension actuators  970 - 1 ,  970 - 2 . The piston  1282   b  is movable by a linear actuator  1282   d  (e.g., a ball screw actuator, as described above, having an electric motor), so as to inversely change the volume of the two chambers  1282   c  to control relative displacement of the two hydraulic actuator mechanisms  974 , for example, to control roll or pitch of the vehicle  100 . By the hydraulic actuator mechanisms  974  being fluidically coupled to opposite sides of the piston  1282   b , the pump unit  1282   b  is not capable by itself of causing simultaneous positive displacement of the two hydraulic actuator mechanism  974 . 
     The pump unit  1282  is operated to control the amount force transferred between the two hydraulic actuator mechanisms  974 . For example, the pump unit  1282  may provide no resistance (e.g., is loose) to transfer substantially all force, high resistance (e.g., is stiff) to transfer substantially no force, or variable resistance (e.g., controlled resistance) to transfer otherwise desirable amount of force between the two hydraulic actuator mechanism  974 . The loads of the two hydraulic actuator mechanisms may be balanced on either side of the piston  1282   b , such that in static conditions, no static load is placed on the pump unit  1282 . 
     To control roll, the vehicle  100  may, for example, include two of the hydraulic circuits  1280  that hydraulically connect left and right suspension actuators  970  at the front and at the rear of the vehicle  100 , respectively. For example, during a sustained turning event as the vehicle  100  rolls about a pitch axis toward an outer side of the vehicle  100  (e.g., the right side during a left turn), the suspension actuator  970 - 2  is on the on outer side of the vehicle  100  (e.g., the right side) and may increase in loading, while the suspension actuator  970 - 1  is on an inner side of the vehicle  100  (e.g., the left side) and may decrease in loading as compared to static conditions. Fluid may be biased by the pump unit  1282  to the hydraulic actuator mechanism  974  of the outside suspension actuator  970 - 2  to increase the displacement of the spring seat of the outside suspension actuator  970 , and be drawn by the pump unit  1282  from the inside suspension actuator  970 - 1  to decrease displacement of the spring seat of the inside suspension actuator  970 - 1  as compared to static conditions. The greater displacement of the outside suspension actuator  970 - 2  offsets increased compression of the spring  974   a , which is caused by increased loading of the outside suspension actuator  970 - 2  as the vehicle  100  travels around a corner and rolls about a roll axis toward the outside of the vehicle  100 . Conversely, the lesser displacement of the inside suspension actuator  970 - 1  offsets the decreased compression of the spring  974   a , which is caused by decreased loading of the inside suspension actuator  970 - 1  as the vehicle  100  travels around the corner and rolls about the roll axis away from the inside of the vehicle  100 . As a result, the outside and the inside of the vehicle  100  experience less net displacement and the passengers thereof may experience less roll than would occur with static spring seats. Furthermore, the linear actuators  672  of the suspension actuators  970  may be operated at a much lower force output than might otherwise might be required to control roll during a sustained turn, thereby decreasing power consumption to resist roll and maintaining capacity (e.g., force and displacement) of the linear actuator  672  to control primary ride (e.g., damping low frequency inputs from the road to the unsprung mass  360 ). 
     To control pitch, the vehicle  100  may, instead, include two of the hydraulic circuits  1280  (e.g., left and right hydraulic circuits  1280 ) that hydraulically connect front and rear suspension actuators  970 - 1 ,  970 - 2  on the left and right sides of the vehicle  100 , respectively. During a sustained braking event, the vehicle  100  may tend to pitch forward about a pitch axis, thereby increasing loading to the front suspension actuator  970 - 1  and may decrease loading to the rear suspension actuator  970 - 2  as compared to static conditions. The pump unit  1282  may bias the fluid to the hydraulic actuator mechanism  974  of the front suspension actuator  970 - 1  to increase the displacement of the spring seat of the front suspension actuator  970 , and may draw the fluid from the hydraulic actuator mechanism  974  of the rear suspension actuator  970 - 2  to decrease displacement of the spring seat rear suspension actuator  970 , as compared to static conditions. The greater displacement of the front suspension actuator  970 - 1  offsets increased compression of the spring  974   a , which is caused by increased loading as the vehicle  100  brakes and pitches forward. Conversely, the lesser displacement of the rear suspension actuator  970 - 2  offsets the decreased compression of the spring  974   a  thereof, which is caused by the decreased loading as the vehicle  100  brakes and pitches away from the rear actuator  970 . As a result, the front and the rear of the vehicle  100  experience less net displacement and the passengers thereof may experience less pitch than would occur with static spring seats. Furthermore, the linear actuators  672  of the suspension actuators  970  may be operated at a much lower force output than might otherwise might be required to control pitch during a sustained braking event, thereby decreasing power consumption and maintaining capacity (e.g., force and displacement) of the linear actuator  672  to control primary ride (e.g., damping low frequency inputs from the road to the unsprung mass  360 ). 
     Referring to  FIG. 13 , a hydraulic circuit  1380  is communication with the hydraulic actuator mechanisms  974  of four of the suspension actuators  970 - 1 ,  970 - 2 ,  970 - 3 ,  970 - 4  (e.g., front left, front right, rear left, and rear right, or alternatively front left, rear left, front right, and rear right). The hydraulic circuit  1380  includes a fixed volume of fluid and a pump unit  1282 , configured as described previously. The pump unit  1282  is operated, as described above, to control displacement and the amount force transferred between the hydraulic actuator mechanisms  974  of the first two suspension actuators  970 - 1 ,  970 - 2  and the second two suspension actuators  970 - 3 ,  970 - 4 . The loads of the two hydraulic actuator mechanisms  974  may be balanced on either side of the piston  1282   b , such that in static conditions, no load is placed on the pump unit  1282 . The hydraulic circuit  1380  may be configured to control pitch of the vehicle  100  with a first of the two chambers  1282   c  in fluidic communication with left and right suspension actuators  970 - 1 ,  970 - 2  at the front of the vehicle  100 , and the other chamber  1282   c  in fluidic communication with left and right suspension actuators  970 - 3 ,  970 - 4  at the rear of the vehicle  100 . As a result, during a sustained braking event, the vehicle  100  may, as described above with respect to  FIG. 12 , pitch less than would a vehicle having static spring seats. Alternatively, the hydraulic circuit  1380  may be configured to control roll of the vehicle  100  with a first of the two chambers  1282   c  in fluidic communication with front and rear suspension actuators  970 ,  970 - 1 ,  970 - 2  on the right of the vehicle  100 , and the other chamber  1282   c  in fluidic communication with front and rear suspension actuators  970 - 3 ,  970 - 4  on the left of the vehicle  100 . As a result, during a sustained turning event, the vehicle  100  may, as described above with respect to  FIG. 12 , roll less than would a vehicle having static spring seats. 
     Referring to  FIG. 14 , a hydraulic circuit  1480  is communication with the hydraulic actuator mechanism  974  of four of the suspension actuators  970 - 1 ,  970 - 2 ,  970 - 3 ,  970 - 4  (e.g., front left, front right, rear left, and rear right). The hydraulic circuit  1480  includes four of the pump units  1282 - 1 ,  1282 - 2 ,  1282 - 3 ,  1282 - 4  configured as described previously. Each of the pump units  1282  is in communication with the two suspension actuators  970  on each side (i.e., left and right) or each end (i.e., front and rear) of the vehicle  100 . As a result, displacement and force transfer can be allocated between each of the four suspension actuators  970  to control roll and pitch of the vehicle  100 , as well as warp (e.g., having uneven displacement or force of at least one of the suspension actuators  970  relative to the two suspension actuators  970  adjacent thereto). 
     The four pump units  1282 - 1 ,  1282 - 2 ,  1282 - 3 ,  1282 - 4  of the hydraulic circuit  1480  are configured to control front roll, rear roll, left pitch, and rear pitch. As such, a first of the pump units  1282 - 1  may be considered a front roll pump unit  1282 , which is in fluidic communication with and controls the relative displacement and force transfer between the hydraulic actuation mechanisms  974  of the front left and the front right suspension actuators  970 - 1 ,  972 - 2 . A second of the pump units  1282  may be considered a rear roll pump unit  1282 , which is in fluidic communication with and controls the relative displacement and force transfer between the hydraulic actuation mechanisms  974  of the rear left and the rear right suspension actuators  970 - 3 ,  970 - 4 . A third the pump units  1282 - 3  may be considered a left pitch pump unit  1282 , which is in fluidic communication with and controls the relative displacement and force transfer between the hydraulic actuation mechanisms  974  of the front left and the rear left suspension actuators  970 - 1 ,  970 - 3 . A fourth of the pump units  1282 - 4  may be considered a right pitch pump unit  1282 , which is in fluidic communication with and controls the relative displacement and force transfer between the hydraulic actuation mechanisms  974  of the front right and the rear right suspension actuators  970 - 2 ,  970 - 4 . As compared to having pumps individually associated with each of the actuator mechanism  974 , the pump units  1282  may be under no static load, since the loads of the two hydraulic actuator mechanisms  974  associated therewith may be balanced on either side of the piston  1282   b . The four pump units  1282 - 1 ,  1282 - 2 ,  1282 - 3 ,  1282 - 4  may be operated to control roll and pitch as described above with respect to  FIG. 12 , as well as to control warp. 
     Referring to  FIG. 15 , a hydraulic circuit  1580  is in communication with the hydraulic actuator mechanism  974  of four of the suspension actuators  970 - 1 ,  970 - 2 ,  970 - 3 ,  970 - 4  (e.g., front left, front right, rear left, and rear right). The hydraulic circuit  1580  further includes fixed volumes of fluid and a pump unit  1582 , which performs the functions of four of the pump units  1282  described with respect to the hydraulic circuit  1480 . The pump unit  1582  may, for example, include four of the pump units  1282  integrated into a single assembly. The pump unit  1582  may be operated to control roll and pitch as described above with respect to  FIG. 11 , as well as to control warp. 
     Referring to  FIG. 16 , a hydraulic circuit  1680  is in communication with the hydraulic actuator mechanisms  974  of four of the suspension actuators  970 - 1 ,  970 - 2 ,  970 - 3 ,  970 - 4  (e.g., front left, front right, rear left, and rear right). The hydraulic circuit  1680  includes fixed volumes of fluid and two pump units  1682 - 1 ,  1682 - 2 . Each pump unit  1682  includes two cylinders  1682   a  and two pistons  1682   b  that are moved in unison by a common actuator  1682   d  (e.g., a ball screw actuator), one piston  1682   b  being movable in and dividing each of the cylinders  1682   a  into two sides. The two sides of each cylinder  1682   a  are in fluidic communication with the two hydraulic actuator mechanisms  974  that are either on the same side (right or left) of the vehicle  100  to control pitch or on the same end (front or back) of the vehicle to control roll. 
     As shown, one of the pump units  1682 - 1  is configured to control roll of the vehicle  100  and may be considered a roll pump unit  1682 . Either side of a first of the cylinders  1682   a  (e.g., a front roll cylinder) is in fluidic communication with the left and right hydraulic actuator mechanisms  974  of the suspension actuators  970 - 1 ,  970 - 2  at the front of the vehicle  100  to control relative displacement and force transfer between the therebetween. Either side of the other of the cylinders  1682   a  (e.g., a rear roll cylinder) is in fluidic communication with the left and right hydraulic actuator mechanism  974  of the suspension actuators  970 - 3 ,  970 - 4  at the rear of the vehicle  100  to control relative displacement and force transfer therebetween. The roll pump unit  1682 - 1  may be operated to control roll of the vehicle  100  in the manner described above with respect to  FIG. 12 . 
     The other of the pump units  1682 - 2  is configured to control pitch of the vehicle  100  and may be considered a pitch pump unit. Either side of a first of the cylinders  1682   a  (e.g., a left pitch cylinder) is in fluidic communication with the front and rear hydraulic actuator mechanisms  974  of the suspension actuators  970 - 1 ,  970 - 3  on the left side of the vehicle to control relative displacement and force transfer therebetween. Either side of the other of the cylinders  1682   a  (e.g., a right pitch cylinder) is in fluidic communication with the front and rear hydraulic actuator mechanisms  974  of the suspension actuators  970 - 2 ,  970 - 4  on the right side of the vehicle  100  to control relative displacement and force transfer therebetween. The hydraulic circuit  1680  is not, however, able to control each of the hydraulic actuator mechanisms  974  independently, such that the hydraulic circuit  1680  cannot achieve warp (as described previously). The two pump units  1682  may, instead of being provided as separate units, be provided as a combined unit (e.g., similar to the pump unit  1582  combining four of the pump units  1282 ). The pitch pump unit  1682 - 1  may be operated to control pitch of the vehicle  100  in the manner described above with respect to  FIG. 12 . 
     Variations of the fluid circuits  1280 ,  1380 ,  1480 ,  1580 , and  1680  include, for example, use of constant displacement pumps, variable fluid volumes, valves (e.g., the isolation valve  1084 ), accumulators (e.g., the accumulator  1086 ), and stability springs (e.g., the stability spring  1082   d ). The constant displacement pumps may be used in place of the pump units  1282 ,  1582 , and  1682  having the piston/cylinder arrangement described previously, for example, by being in fluidic communication on opposite sides thereof with the hydraulic actuator mechanisms  974  of the different suspension actuators  970  to control relative displacement and force transfer therebetween. Variable fluid volumes may be provided by a pump and a reservoir, which add to or remove fluid from the various fluid circuit so as to cooperative increase or decrease displacement of the hydraulic actuator mechanisms  974  (e.g., to change the ride height of the vehicle and/or to replenish lost fluid, such as from leakage). The isolation valves  1084  may be in fluidic communication with each of the hydraulic actuator mechanism  974  or each of the respective pump units to provide a zero-energy hold (e.g., by closing the valve to prevent fluid flow thereto. The accumulators  1086  may be in fluidic communication with each of the hydraulic actuator mechanisms  974  the responsiveness of load transfer between linked hydraulic actuator mechanisms  974 , and each of the accumulators  1086  may include an isolation valve to increase responsiveness of the load transfer between the linked hydraulic actuator mechanisms  974 . The stability springs  1082   d  may be provided on one or both sides of the respective pistons to provide passive stability (e.g., pitch and/or roll stability) in case of failure of the actuators. Referring to  FIG. 17 , a hydraulic circuit  1780  is a variation of the hydraulic circuit  1680 , but additionally includes a fluid source to provides fluid level control. More particularly, the hydraulic circuit  1780  additionally includes a fluid reservoir  1782  and a pump  1784  that are in fluidic communication with each of the hydraulic actuator mechanisms  974  of the suspension actuators  970 . Valves (shown; not labeled) may be associated with each of the hydraulic actuator mechanisms  974 , which allow independent control of additional fluid to each hydraulic actuator mechanism  974  from the pump  1784 . By adding or removing fluid from the hydraulic circuit  1780 , the displacement of each of the hydraulic actuator mechanisms  974  may be controlled independently, such that the ride height of the vehicle  100  may be controlled, in addition to roll and pitch in the manners described previously. Similarly, each of the hydraulic circuits  1280 ,  1380 ,  1480 ,  1580  may include the fluid reservoir  1782 , the pump  1784 , and associated valves by which fluid may be added. 
     Referring to  FIG. 18 , a hydraulic circuit  1880  is another variation of the hydraulic circuit  1680 , but additionally includes accumulators  1882  that are each in fluidic communication with one of the suspension actuators  970 . Each of the accumulators  1882  may additionally include an isolation valve (not shown). The accumulators  1882  provide compliance in the fluid circuit as referenced previously. Similarly, each of the other hydraulic circuits  1280 ,  1380 ,  1480 ,  1580 ,  1680 ,  1780  may also include accumulators associated with each of the suspension actuators  970  thereof. 
     Referring back to  FIG. 10 , the pump units  1282 ,  1582 ,  1682  may each include the stability springs  1082   d , which function to provide passive force to the respective pistons to pressurize the fluid upon failure or loss of power to the actuators thereof.

Metadata:
Filing Date: 20180829
Publication Date: 20210921
Grant Date: 20210921
Priority Date: 20170925
Inventors: HALL, JONATHAN L.
CARTER, TROY A.
KEAS, PAUL J.
Assignee: APPLE INC
CPC Classifications: [{"code": "B60G2204/62", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2800/012", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/43", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/422", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/416", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/413", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/15", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0165", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/016", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/0152", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G17/015", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2500/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0272", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/413", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2800/012", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/416", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/016", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/015", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/0152", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G17/0157", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/0165", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/43", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/422", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/15", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0408", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2204/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2800/012", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/15", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0408", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/43", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0165", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/422", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/413", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/015", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/0152", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G2202/416", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0157", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G17/016", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 77767857