Vehicle suspension
View Patent ↗An active suspension for a wheeled vehicle is configured for improved occupant comfort, with an advantageously low maximum horizontal kinetic displacement of the wheel assembly, and particularly low horizontal inertial and tire loads, as the suspension moves through jounce and rebound under active control. The front suspension is a strut configuration, with an active actuator in place of the strut, and the rear suspension is a double wishbone configuration.
1. A wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit the wheel assembly to move relative to the sprung body through a jounce and rebound vertical travel limited by mechanical stops, the 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;
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; and
an actuator connected to both the wheel assembly and the sprung body and capable of applying an active control force between the body and wheel assembly to move the wheel assembly over an active control range comprising at least 80 percent of the vertical travel of the wheel assembly;
the upper and lower pivots and relative rotation centers being positioned to produce a maximum horizontal kinetic displacement of the wheel assembly of less than about 4.0 millimeters as the actuator moves through the active control range.
2. The wheel suspension of claim 1 wherein the maximum horizontal kinetic displacement is less than about 1.5 millimeters.
3. The wheel suspension of claim 1 wherein the maximum horizontal kinetic displacement is less than about 0.75 millimeters.
4. The wheel suspension of claim 1 wherein the maximum horizontal kinetic displacement is less than about 0.30 millimeters.
5. The wheel suspension of claim 1 wherein horizontal kinetic displacement as measured along an axis running in a direction of travel of the vehicle is less than about 0.5 millimeters.
6. The wheel suspension of claim 1 wherein horizontal kinetic displacement as measured along an axis extending perpendicular to a direction of travel of the vehicle is less than about 3.5 millimeters.
7. The wheel suspension of claim 1 wherein the wheel assembly is a rear wheel assembly of an automobile.
8. The wheel suspension of claim 7 wherein the relative rotational centers are disposed rearward and outboard of their respective pivots.
9. The wheel suspension of claim 7 wherein the wheel assembly has a horizontally unsprung mass weight greater than about 120 pounds (530 Newtons).
10. The wheel suspension of claim 9 wherein the wheel assembly includes a damper mass vertically sprung with respect to a remainder of the wheel assembly.
11. The wheel suspension of claim 1 wherein the active control range covers a vertical displacement of the gravitational center of the wheel assembly of at least 0.2 meters.
12. The wheel suspension of claim 1 wherein the actuator has an active stroke sufficient to displace the gravitational center of the wheel assembly through its entire vertical travel.
13. The 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 vertical travel.
14. The wheel suspension of claim 1 defining a geometry selected to produce a maximum wheel camber change of less than about 3.0 degrees through said vertical travel.
15. The wheel suspension of claim 1 wherein the upper relative rotation center and upper pivot are disposed along a first generally horizontal line, and the lower relative rotation center and lower pivot are disposed along a second generally horizontal line, with the automobile at rest and loaded to its design weight.
16. The wheel suspension of claim 15 wherein the upper and lower rotation centers are separated from their respective pivots by different arm lengths.
17. The wheel suspension of claim 1 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.
18. The wheel suspension of claim 17 wherein the mechanical stops are positioned to allow at least about 3.0 inches (75 millimeters) each of jounce and rebound.
19. The wheel suspension of claim 18 wherein the mechanical stops are positioned to allow at least about 4.0 inches (100 millimeters) each of jounce and rebound.
20. The wheel suspension of claim 1 wherein the pivots are located inboard of their relative rotational centers.
21. The wheel suspension of claim 1 wherein lateral displacement of a tire patch defined between wheel assembly and a support surface, multiplied by lateral tire stiffness, yields a maximum product of less than about 500 pounds (2200 Newtons).
22. The wheel suspension of claim 21 wherein the maximum product of lateral displacement of the tire patch and lateral tire stiffness is less than about 150 pounds (670 Newtons).
23. The wheel suspension of claim 1 wherein overall angulation of a wheel rim of the wheel assembly about a vertical axis through the vertical travel, multiplied by a cornering stiffness of a tire of the wheel assembly, yields a product of less than about 30 pounds (130 Newtons).
24. The wheel suspension of claim 1 defining a geometry selected to produce a maximum tread width change of less than about 5 millimeters through said vertical travel.
25. A wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit the wheel assembly to move relative to the sprung body through a jounce and rebound vertical travel limited by mechanical stops, the suspension including
an actuator connected to both the wheel assembly and the sprung body and capable of applying an active control force between the body and wheel assembly to move the wheel assembly through an active control range along its vertical travel; and
a structural link coupled to the wheel assembly to define a relative rotation center, and rotationally coupled to the sprung body at a pivot;
the suspension forming a geometry selected to produce a maximum lateral displacement of the gravitational center of the wheel assembly of less than about 20 millimeters through the jounce and rebound vertical travel, and a maximum wheel camber change of less than about 3.0 degrees through said jounce and rebound vertical travel.
26. The wheel suspension of claim 25 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.
27. The wheel suspension of claim 25 for suspending a rear wheel assembly from a sprung body of a wheeled vehicle and defining a geometry selected to produce a maximum longitudinal displacement of less than about 4.0 millimeters.
28. The wheel suspension of claim 25 for suspending a front wheel assembly from a sprung body of a wheeled vehicle and defining a geometry selected to produce a maximum longitudinal displacement of less than about 5.0 millimeters.
29. The wheel suspension of claim 25 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.
30. The wheel suspension of claim 29 wherein the active control range covers a vertical displacement of the gravitational center of the wheel assembly of at least 0.2 meters.
31. The wheel suspension of claim 25 defining a geometry selected to produce a maximum wheel toe change of less than about 0.1 degrees through said vertical travel.
32. The wheel suspension of claim 25 wherein lateral displacement of a tire patch defined between wheel assembly and a support surface, multiplied by lateral tire stiffness, yields a maximum product of less than about 500 pounds (2200 Newtons).
33. The wheel suspension of claim 25 wherein overall angulation of a wheel rim of the wheel assembly about a vertical axis through the vertical travel, multiplied by a cornering stiffness of a tire of the wheel assembly, yields a product of less than about 30 pounds (130 Newtons).
34. The wheel suspension of claim 25 defining a geometry selected to produce a maximum tread width change of less than about 20 millimeters through said vertical travel.
35. A wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit the wheel assembly to move vertically relative to the sprung body, the suspension including an actuator connected to both the wheel assembly and the sprung body and capable of applying an active control force between the body and wheel assembly to move the wheel assembly vertically over a total active control range of vertical wheel displacement, the suspension forming a geometry selected to produce a maximum horizontal kinetic displacement of the wheel assembly of less than about 3.0 millimeters as the wheel assembly is moved through said total active control range of vertical wheel displacement.
36. The wheel suspension of claim 35 wherein the maximum horizontal kinetic displacement is less than about 1.5 millimeters.
37. The wheel suspension of claim 35 wherein horizontal kinetic displacement as measured along an axis running in a direction of travel of the vehicle is less than about 0.5 millimeters.
38. The wheel suspension of claim 35 wherein horizontal kinetic displacement as measured along an axis extending perpendicular to a direction of travel of the vehicle is less than about 3.5 millimeters.
39. The wheel suspension of claim 35 wherein the wheel assembly is a rear wheel assembly of an automobile.
40. The wheel suspension of claim 39 wherein the relative rotational centers are disposed rearward and outboard of their respective pivots.
41. The wheel suspension of claim 35 wherein the active control range covers a vertical displacement of the gravitational center of the wheel assembly of at least 0.2 meters.
42. The wheel suspension of claim 35 defining a geometry selected to produce a wheel toe change of less than about 0.1 degrees through said vertical travel.
43. The wheel suspension of claim 35 defining a geometry selected to produce a wheel camber change of less than about 3.0 degrees through said vertical travel.
44. The wheel suspension of claim 35 wherein the mechanical stops are positioned to allow at least 2.0 inches (50 millimeters) of jounce and 2.0 inches (50 millimeters) of rebound.
45. The wheel suspension of claim 35 wherein lateral displacement of a tire patch defined between wheel assembly and a support surface, multiplied by lateral tire stiffness, yields a maximum product of less than about 500 pounds (2200 Newtons).
46. The wheel suspension of claim 35 wherein overall angulation of a wheel rim of the wheel assembly about a vertical axis through the vertical travel, multiplied by a cornering stiffness of a tire of the wheel assembly, yields a product of less than about 30 pounds (130 Newtons).
47. A rear wheel suspension for suspending a rear wheel assembly from a sprung body of an automobile, and adapted to permit the rear wheel assembly to move relative to the sprung body through a jounce and rebound vertical travel of at least two inches total, as limited by mechanical stops, the 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;
the suspension defining a geometry selected to produce a maximum lateral displacement of the gravitational center of the wheel assembly of less than about 10 millimeters through said vertical travel, and a maximum wheel camber change of less than about 3.0 degrees through said vertical travel.
48. The wheel suspension of claim 47 further 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 along its vertical travel.
49. The wheel suspension of claim 47 wherein the upper relative rotation center and upper pivot are disposed along a first generally horizontal line, and the lower relative rotation center and lower pivot are disposed along a second generally horizontal line, with the automobile at rest and loaded to its design weight.
50. The wheel suspension of claim 47 wherein the maximum lateral displacement of the gravitational center of the wheel assembly is less than about 5 millimeters.
51. The wheel suspension of claim 47 wherein the maximum wheel camber change is less than about 2.0 degrees through said vertical travel.
52. A wheel suspension for suspending a wheel assembly from a sprung body of a wheeled vehicle, and adapted to permit the wheel assembly to move relative to the sprung body through a jounce and rebound vertical travel limited by mechanical stops, the suspension comprising:
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; and
an actuator connected to both the wheel assembly and the sprung body to define an upper relative rotation center, and rotationally coupled to the sprung body at an upper pivot, the actuator capable of applying an active control force between the body and wheel assembly to move the wheel assembly over an active control range comprising at least 80 percent of the vertical travel of the wheel assembly;
the upper and lower pivots and relative rotation centers being positioned to produce a maximum horizontal kinetic displacement of the wheel assembly of less than about 4.0 millimeters as the actuator moves through the active control range.
53. The wheel suspension of claim 52 wherein the wheel assembly is a front wheel assembly of an automobile, and wherein the horizontal kinetic displacement as measured along an axis extending perpendicular to a direction of travel of the vehicle is less than about 2.0 millimeters.
54. The wheel suspension of claim 52 defining a geometry selected to produce a maximum tread width change of less than about 10 millimeters through said vertical travel.
55. The wheel suspension of claim 52 wherein the maximum horizontal kinetic displacement is less than about 1.5 millimeters.
56. The wheel suspension of claim 55 wherein the maximum horizontal kinetic displacement is less than about 0.30 millimeters.
57. The wheel suspension of claim 52 wherein the wheel assembly has a horizontally unsprung mass weight greater than about 120 pounds (530 Newtons).
58. The wheel suspension of claim 57 wherein the wheel assembly includes a damper mass vertically sprung with respect to wheel a remainder of the wheel assembly.
59. The wheel suspension of claim 52 wherein the active control range covers a vertical displacement of the gravitational center of the wheel assembly of at least 0.2 meters.
60. The wheel suspension of claim 52 defining a geometry selected to produce a wheel toe change of less than about 0.1 degrees through said vertical travel.
61. The wheel suspension of claim 52 wherein the mechanical stops are positioned to allow at least 2.0 inches (50 millimeters) of jounce and 2.0 inches (50 millimeters) of rebound.
62. The wheel suspension of claim 52 wherein lateral displacement of a tire patch defined between wheel assembly and a support surface, multiplied by lateral tire stiffness, yields a maximum product of less than about 500 pounds (2200 Newtons).
63. The wheel suspension of claim 52 wherein overall angulation of a wheel rim of the wheel assembly about a vertical axis through the vertical travel, multiplied by a cornering stiffness of a tire of the wheel assembly, yields a product of less than about 30 pounds (130 Newtons).
64. The wheel suspension of claim 52 defining a geometry selected to produce a maximum tread width change of less than about 20 millimeters through said vertical travel.