Active vehicle suspension
View Patent ↗An active wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit a center of the wheel assembly to move relative to the sprung body through a jounce and rebound travel and defining a wheel center locus path relative to the body, the suspension including an actuator connected to both the wheel assembly and the sprung body and adapted to apply an active control force between the body and wheel assembly to move the wheel assembly. The wheel suspension is configured such that a tangent to the wheel center locus path is inclined rearward with respect to vertical with the wheel center at nominal ride height.
1. An active wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit a center of the wheel assembly to move relative to the sprung body through a jounce and rebound travel and defining a wheel center locus path relative to the body, the suspension comprising:
an actuator connected to both the wheel assembly and the sprung body and adapted to apply an active control force between the body and wheel assembly to move the wheel assembly;
wherein a tangent to the wheel center locus path is inclined rearward at an angle that corresponds to a resultant direction of a road surface force such that the active control force is applied on the wheel assembly in a direction opposite to the resultant direction.
2. The active wheel suspension of claim 1 wherein the suspension is configured to move the wheel center through jounce and rebound along a substantially linear path with respect to the body, the linear path inclined rearward with respect to vertical.
3. The active wheel suspension of claim 1 wherein the tangent to the wheel center locus path with the wheel center at nominal ride height defines a recession angle in a fore-aft plane with respect to vertical, the recession angle being between about 1 and 5 degrees.
4. The active wheel suspension of claim 3 wherein the recession angle is between about 2 and 4 degrees.
5. The active wheel suspension of claim 4 wherein the recession angle is about 3 degrees.
6. The active wheel suspension of claim 1 , further comprising an actuator adapted to vary the rearward inclination of the tangent to the wheel center locus path as a function of vehicle speed.
7. The active wheel suspension of claim 6 , wherein the magnitude of the rearward inclination of the tangent to the wheel center locus path is configured to vary inversely with vehicle speed.
8. The active wheel suspension of claim 1 wherein the actuator comprises an electromagnetic actuator.
9. The active wheel suspension of claim 8 wherein the actuator comprises a linear motor.
10. The active wheel suspension of claim 1 wherein the wheel suspension comprises a front wheel suspension of an automobile.
11. The active wheel suspension of claim 10 wherein the actuator is positioned as a strut.
12. The active wheel suspension of claim 1 wherein the wheel suspension comprises a rear wheel suspension of an automobile.
13. The active wheel suspension of claim 1 wherein the wheel assembly has a horizontally unsprung mass weight greater than about 120 pounds.
14. The active wheel suspension of claim 1 wherein the wheel assembly includes a damper mass vertically sprung with respect to the wheel assembly.
15. The active wheel suspension of claim 1 configured to produce an active control force between the body and wheelassembly over an active control range of at least 0.2 meters along the wheel center locus path.
16. The active wheel suspension of claim 1 further comprising mechanical stops limiting a jounce and rebound travel, wherein the mechanical stops are positioned to allow at least about 2.0 inches (50 millimeters) of jounce and about 2.0 inches (50 millimeters) of rebound.
17. The active wheel suspension of claim 1 defining a geometry selected to produce a maximum tread width change of less than about 5 millimeters through said jounce and rebound.
18. The active wheel suspension of claim 1 further comprising a structural link coupled to the wheel assembly to define a relative rotation center, and rotationally coupled to the sprung body at a pivot.
19. The active wheel suspension of claim 18 wherein the structural link is a first structural link coupled to the wheel assembly to define a first relative rotation center, and rotationally coupled to the sprung body at a first pivot, the suspension further comprising a second structural link coupled to the wheel assembly to define a second relative rotation center above the first relative rotation center, and rotationally coupled to the sprung body at a second pivot above the first pivot.
20. The active wheel suspension of claim 1 defining a geometry selected to produce a maximum horizontal kinetic displacement of the wheel assembly of less than about 4.0 millimeters as the actuator moves through its active control range.
21. The active wheel suspension of claim 20 wherein the active control range covers a vertical displacement of a gravitational center of the wheel assembly of at least 0.2 meters.
22. The active wheel suspension of claim 1 defining a geometry selected to produce a maximum wheel toe change of less than about 0.1 degrees through said jounce and rebound travel.
23. The active wheel suspension of claim 1 wherein lateral displacement of a tire patch defined between the wheel assembly and a support surface, multiplied by lateral tire stiffness, yields a maximum product of less than about 500 pounds (2200 Newtons).
24. The active wheel suspension of claim 1 wherein overall angulation of a wheel rim of the wheel assembly about a vertical axis through the jounce and rebound travel, multiplied by a cornering stiffness of a tire of the wheel assembly, yields a product of less than about 30 pounds (130 Newtons).
25. The active wheel suspension of claim 1 , wherein the wheel suspension comprises a rear wheel suspension, the rear wheel suspension comprising:
an upper structural member coupled to the wheel assembly to define an upper relative rotation center, and rotationally coupled to the sprung body at an upper pivot; and
a lower structural member coupled to the wheel assembly to define a lower relative rotation center disposed on a side of a gravitational center of the wheel assembly opposite the upper relative rotation center, and rotationally coupled to the sprung body at a lower pivot.
26. An active wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit a center of the wheel assembly to move relative to the sprung body through a jounce and rebound travel and defining a wheel center locus path relative to the body, the suspension comprising:
an actuator connected to both the wheel assembly and the sprung body and adapted to apply an active control force between the body and wheel assembly to move the wheel assembly;
wherein a tangent to the wheel center locus path is inclined rearward at an angle that corresponds to a resultant direction of a road surface force such that the active control force is applied on the wheel assembly in a direction opposite to the resultant direction, the angle being between about 1 and 5 degrees with the wheel center at nominal ride height;
wherein the suspension is configured to move the wheel center through jounce and rebound along a substantially linear path with respect to the body, the linear path inclined rearward with respect to vertical.
27. A method of actuating an active wheel suspension of a wheeled vehicle, the method comprising:
applying an active control force between a sprung vehicle body and wheel assembly to move the wheel assembly; and
moving a center of the wheel assembly relative to the sprung body through a jounce and rebound travel along a wheel center locus path relative to the body, wherein the tangent to the wheel center locus path is inclined rearward at an angle that corresponds to a resultant direction of a road surface force such that the active control force is applied on the wheel assembly in a direction opposite to the resultant direction.
28. The method of claim 27 further comprising moving the center of the wheel assembly through jounce and rebound along a substantially linear path with respect to the body.
29. The method of claim 27 further comprising varying the rearward inclination of the tangent to the wheel center locus path as a function of vehicle speed.
30. The method of claim 29 wherein the magnitude of the rearward inclination of the tangent to the wheel center locus path is configured to vary inversely with vehicle speed.
31. An active wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit a center of the wheel assembly to move relative to the sprung body through a jounce and rebound travel, the suspension comprising: an electromagnetic actuator connected to both the wheel assembly and the sprung body and adapted to apply an active control force between the body and wheel assembly to move the wheel assembly, the active control force being applied on the wheel assembly in a direction opposite to a resultant direction of a road surface force and at an angle corresponding to an angle of the resultant force; a housing of the actuator, and a mechanical stop within the housing.
32. The active wheel suspension of claim 31 wherein the actuator comprises a linear motor.
33. The active wheel suspension of claim 31 wherein the wheel suspension comprises a front wheel suspension of an automobile.
34. The active wheel suspension of claim 33 wherein the actuator is positioned as a strut.
35. The active wheel suspension of claim 31 wherein the wheel suspension comprises a rear wheel suspension of an automobile.
36. The active wheel suspension of claim 31 , wherein the mechanical stop limits a jounce travel.
37. The active wheel suspension of claim 36 , wherein the mechanical stop is positioned to allow at least about 2.0 inches (50 millimeters) of jounce.
38. The active wheel suspension of claim 31 , wherein the mechanical stop limits a rebound travel.
39. The active wheel suspension of claim 38 , wherein the mechanical stop is positioned to allow at least about 2.0 inches (50 millimeters) of rebound.
40. The active wheel suspension of claim 31 , further including, an additional mechanical stop within the housing.
41. The active wheel suspension of claim 40 , wherein one of the mechanical stop and additional mechanical stop limits a jounce travel, and the other of the mechanical stop and additional mechanical stop limits a rebound travel.
42. The active wheel suspension of claim 41 , wherein one of the mechanical stop and additional mechanical stop is positioned to allow at least about 2.0 inches (50 millimeters) of jounce, and the other of the mechanical stop and additional mechanical stop is positioned to allow at least about 2.0 inches (50 millimeters) of rebound.
43. The active wheel suspension of claim 35 wherein the actuator is positioned as a strut.