Height control system and sensor therefor

• US 20030205869A1
• Filed: 04/22/2003
• Published: 11/06/2003
• Est. Priority Date: 05/25/2000
• Status: Active Grant

• Current Assignee: Haldex Brake Corporation
• Original Assignee: Haldex Brake Corporation
• Inventors: Schutt, Randy
• Granted Patent: US 6,991,239 B2
• Time in Patent Office: Days
• US Class Current: 280/5.514
• CPC Class Codes: B60G 17/0155 pneumatic unit
• CPC Class Codes: B60G 17/019 characterised by the type of sensor or the arrangement thereof B60G17/01941 takes precedence
• CPC Class Codes: B60G 17/01933 Velocity, e.g. relative velocity-displacement sensors
• CPC Class Codes: B60G 2200/31 with two trailing arms rigidly connected to the axle
• CPC Class Codes: B60G 2202/152 Pneumatic spring
• CPC Class Codes: B60G 2204/11 Mounting of sensors thereon
• CPC Class Codes: B60G 2204/143 on the vehicle body or chassis
• CPC Class Codes: B60G 2204/1482 on rigid axle by elastic mount
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2401/14 Photo or light sensitive means, e.g. Infrared
• CPC Class Codes: B60G 2401/144 Fiber optic sensor
• CPC Class Codes: B60G 2401/25 Capacitance type, e.g. as level indicator
• CPC Class Codes: B60G 2401/26 Resistance type, e.g. as level indicator
• CPC Class Codes: B60G 2500/201 Air spring system type
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes

Abstract

A sensor for a height control system in a trailing arm suspension uses a transducer to detect changes in position of a trailing arm relative to a vehicle and sends a proportional signal to a microprocessor that, in turn, actuates a pneumatic valve operably connected to an air spring between the trailing arm and the vehicle. The transducer includes an optical bridge, a variable capacitor, or a flexible variable resistor.

Claims

1. A height control system for a vehicle (12) having a predetermined ride height comprising a trailing arm suspension (10) having a pair of trailing arm assemblies for carrying an axle (32) supporting ground engaging wheels, each of the trailing arm assemblies having an arm (14) with one portion pivotally mounted to the vehicle and an air spring (20) positioned between the vehicle and another portion of the arm to resist the pivotal movement of the arm toward the vehicle, and an air system (112, 116) for at least supplying pressurized to the air spring, the height control system comprising:

a selectively actuatable valve (114) adapted to selectively fluidly connect the air spring to either the air system or the atmosphere for selectively introducing or exhausting air from the air spring to effect the relative movement of the trailing arm and the vehicle and thereby alter the vehicle ride height;

a transducer sensor (40, 140, 240, 340, 440, 540, 640) operably coupled (42, 442, 542, 642) to the trailing arm that senses pivotal movement of the trailing arm and sends an output signal proportional to the amount of pivotal movement of the trailing arm; and

a controller (110) coupled to the transducer and to the valve wherein the controller receives the transducer output signal and selectively actuates the valve in response to the value of the output signal to operate the height control system between an off mode, where the air spring is fluidly disconnected from the air system and from atmosphere, a fill mode, where the valve fluidly connects the air spring to the air system, and an exhaust mode, where the valve fluidly connects the air spring to atmosphere, to maintain the vehicle at the predetermined ride height.

2. The height control system according to claim 1 wherein the output signal is representative of the pivotal movement of the trailing relative to a reference position for the trailing arm.

3. The height control system according to claim 2 wherein when the trailing arm is in the trailing arm reference position, the vehicle is at the predetermined ride height.

4. The height control system according to claim 1 wherein the output signal is representative of the change in height of the trailing arm corresponding to the sensed pivotal movement.

5. The height control system according to claim 1 wherein the transducer sensor is a light sensor (40, 140, 240).

6. The height control system according to claim 5 wherein the light sensor comprises an optical bridge (90, 190) and a light emitter (70, 170) that projects light onto the optical bridge and the optical bridge generates the output signal which corresponds to the intensity of the projected light across the optical bridge.

7. The height control system according to claim 6 wherein the optical bridge comprises multiple spaced photosensitive cells (98, 100, 198, 200).

8. The height control system according to claim 7 wherein the light emitter is operably coupled (42) to the trailing arm wherein the pivotal movement of the trailing arm correspondingly moves the light emitter to thereby move the location where the projected light contacts the light sensor to change the light intensity seen by each photosensitive cell.

9. The height control system according to claim 8 and further comprising a light diffuser panel (94) disposed between the light emitter and the optical bridge.

10. The height control system according to claim 8 wherein the light emitter comprises a light source (78, 178) and a wall with a diffraction slit (176) disposed between the light source and the optical bridge so that the light projected from the light source passes through the diffraction slit and is diffracted prior to reaching the optical bridge.

11. The height control system according to claim 10 and further comprising a collimating lens (180) disposed between the light source and the diffraction slit.

12. The height control system according to claim 6 and further comprising fresnel lens (180) disposed between the light emitter and the optical bridge and the fresnel lens is operably connected to the trailing arm wherein the pivotal movement of the trailing arm correspondingly moves the fresnel lens.

13. The height control system according to claim 1 wherein the transducer sensor is a variable-capacitance capacitor (344) operably coupled to the trailing arm so that the pivoting of the trailing arm results in a corresponding change in the capacitance of the variable capacitor.

14. The height control system according to claim 13 wherein the variable-capacitance capacitor comprises a capacitor bridge circuit (352, 354) that generates the output signal.

15. The height control system according to claim 14 wherein the capacitor bridge circuit comprises first and second capacitors (352, 354) having variable capacitance and the output signal corresponds to the capacitance differential between the first and second capacitors.

16. The height control system according to claim 15 wherein the capacitor bridge comprises first and second electrically isolated plates (348) and a moveable plate (346) having a portion overlying each of the first and second electrically isolated plates and operably coupled to the trailing arm such that the pivoting movement of the trailing arm results in a corresponding movement of the moveable plate to change the size of the portion of the moveable plate overlying each of the first and second plates to thereby vary the capacitance of each capacitor.

17. The height control system according to claim 1 wherein the transducer sensor is a variable resistor (444).

18. The height control system according to claim 17 wherein the variable resistor comprises a flexible strip (444) that changes in resistance as the strip is bent.

19. The height control system according to claim 18 wherein the flexible strip is positioned within the air spring to operably couple the bending of the flexible strip to the pivoting of the trailing arm.

20. The height control system according to claim 18 wherein the flexible strip is located on a shock absorber (27) for the trailing arm suspension and which extends between trailing arm and the vehicle.

21. The height control system according to claim 18 and further comprising a flexible support (442) on which the flexible strip is mounted.

22. The height control system according to claim 21 wherein the flexible support is spring metal.

23. The height control system according to claim 22 wherein the flexible support has a preformed shape to control the bending profile of the flexible strip.

24. The height control system according to claim 23 wherein the preformed shape bell-shaped curve when viewed in profile.

25. The height control system according to claim 23 wherein the preformed shape is a helix.

26. The height control system according to claim 1 wherein the controller comprises a microprocessor (374, 530) for analyzing the transducer output signal and controlling the operational mode of the valve in response to the analyzed signal.

27. A trailing arm suspension for a vehicle (12) having a predetermined ride height, comprising:

a pair of trailing arm assemblies carrying an axle (32) for mounting ground engaging wheels, each of the trailing arm assemblies comprising;

an arm (14) on each trailing arm assembly with one portion adapted to be pivotally mounted to a vehicle;

an air spring (20) on another portion of each arm to be positioned between the vehicle and the arm to resist the pivotal movement of the arm relative to the vehicle;

an air system (112, 116) for supplying pressurized to each air spring;

a selectively actuatable valve (114) for each air spring adapted to selectively fluidly connect the air spring to either the air system or to atmosphere for selectively introducing or exhausting air from the air bag to effect the relative movement of the trailing arm and the vehicle and thereby alter the vehicle ride height;

a transducer sensor (40, 140, 240, 340, 440, 540, 640) operably coupled (42, 442, 542, 642) to one of the trailing arms and senses the pivotal movement of the trailing arm and sends an output signal proportional to the amount of pivotal movement of the trailing arm; and

a controller (110) coupled to the transducer and to the valve wherein the controller receives the transducer output signal and selectively actuates the valve in response to the value of the output signal to operate the height control system between an off mode, where the air spring is fluidly disconnected from the air system and from atmosphere, a fill mode, where the valve fluidly connects the air spring to the air system, and an exhaust mode, where the valve fluidly connects the air spring to the atmosphere, to maintain the vehicle at the predetermined ride height.

28. The trailing arm suspension according to claim 27 wherein the output signal is representative of the pivotal movement of the trailing relative to a reference position for the trailing arm.

29. The trailing arm suspension according to claim 28 wherein when the trailing arm is in the trailing arm reference position, the vehicle is at the predetermined ride height.

30. The trailing arm suspension according to claim 27 wherein the output signal is representative of the change in height of the trailing arm corresponding to the sensed pivotal movement.

31. The trailing arm suspension according to claim 27 wherein the transducer is a light sensor (40, 140, 240).

32. The trailing arm suspension according to claim 31 wherein the light sensor is an optical bridge (90, 190) and further comprising a light emitter (70, 170) that projects light onto the optical bridge and the optical bridge generates the output signal which corresponds to the intensity of the projected light across the optical bridge.

33. The trailing arm suspension according to claim 27 wherein the transducer is a variable capacitor (344) operably coupled to the trailing arm so that the pivoting of the trailing arm results in a corresponding change in the capacitance of the variable capacitor.

34. The trailing arm suspension according to claim 33 wherein the variable capacitor comprises a capacitor bridge circuit (352, 354) that generates the output signal.

35. The trailing arm suspension according to claim 27 wherein the transducer is a variable resistor (444).

36. The trailing arm suspension according to claim 35 wherein the variable resistor comprises a flexible strip (444) that changes in resistance as the strip is bent.

37. The trailing arm suspension according to claim 36 and further comprising a flexible support (442) on which the flexible strip is mounted.

38. The trailing arm suspension according to claim 27 wherein the controller comprises a microprocessor (374, 530) for analyzing the transducer output signal and controlling the operational mode of the valve in response to the analyzed signal.

39. A suspension for a vehicle (12) having a predetermined ride height, comprising:

an arm assembly carrying an axle (32) for mounting ground engaging wheels and comprising;

an arm (14) with one portion adapted to be moveably mounted to a vehicle;

an actuator (20) extending between the vehicle and the arm for moving the vehicle relative to the arm to adjust the ride height of the vehicle;

a transducer sensor (40, 140, 240, 340, 440, 540, 640) operably coupled (42, 442, 542, 642) to one of the arm and the vehicle and sensing the relative movement between the arm and the vehicle and sending an output signal proportional to the amount of relative movement; and

a controller (110) coupled to the transducer and to the actuator wherein the controller receives the transducer output signal and selectively actuates the actuator in response to the value of the output signal to relatively move the arm and the vehicle to maintain the vehicle at the predetermined ride height.

40. The suspension according to claim 39 wherein the output signal is representative of the pivotal movement of the arm relative to a reference position for the trailing arm.

41. The suspension according to claim 39 wherein when the arm is in an arm reference position, the vehicle is at the predetermined ride height.

42. The suspension according to claim 39 wherein the transducer sensor is operably coupled to the arm and the output signal is representative of the relative change in vehicle height corresponding to the sensed movement of the arm.

43. The suspension according to claim 42 wherein the transducer sensor is a light sensor (40, 140, 240).

44. The suspension according to claim 43 wherein the light sensor is an optical bridge (90, 190) and further comprising a light emitter (70, 170) that projects light onto the optical bridge and the optical bridge generates the output signal which corresponds to the intensity of the projected light across the optical bridge.

45. The suspension according to claim 39 wherein the transducer sensor is a variable capacitor (344) operably coupled to the arm so that the movement of the arm results in a corresponding change in the capacitance of the variable capacitor and the output signal corresponds to the change in the capacitance.

46. The suspension according to claim 45 wherein the variable capacitor comprises a capacitor bridge circuit (352, 354) that generates the output signal.

47. The suspension according to claim 39 wherein the transducer sensor is a variable resistor (444).

48. The suspension according to claim 47 wherein the variable resistor comprises a flexible strip (444) that changes in resistance as the strip is bent.

49. The suspension according to claim 48 and further comprising a flexible support (442) on which the flexible strip is mounted.

50. The suspension according to claim 49 wherein the flexible support is mounted to the actuator.

51. The suspension according to claim 50 wherein the actuator is an air spring (20).

52. The suspension according to claim 39 wherein the controller comprises a microprocessor (374, 530) for analyzing the transducer sensor output signal and controlling the operation of the actuator in response to the analyzed signal.

53. The suspension according to claim 39 wherein the suspension is a trailing arm suspension comprising a trailing arm pivotally mounted to the vehicle, and an air spring positioned between the trailing arm and the vehicle for relatively moving the trailing arm relative to the vehicle by the inflation or deflation of the air spring, with the trailing arm is the arm and the air spring is the actuator.

54. The suspension according to claim 54 and further comprising a valve selectively coupling the air spring to a source of pressurized air and atmosphere, and the vale is operably coupled to the controller whereby the controller selectively actuates the valve to couple the air spring to the source of pressurized air and the atmosphere to thereby inflate or deflate the air spring to adjust the height of the vehicle.

55. A sensor for sensing the position of a first movable object relative to a second movable object characterized by:

a transducer (40, 140, 240, 340, 440, 540, 640) having a portion thereof adapted to be operably coupled to one of the first and second movable objects to sense physical movement of the first and second movable objects relative to each other, and adapted to send a signal responsive to said movement.

56. The sensor according to claim 55 wherein the transducer output signal is representative of the rotational movement of the moveable object relative to a reference position for the moveable object.

57. The sensor according to claim 55 wherein the transducer sensor is a light sensor (40, 140, 240).

58. The sensor according to claim 57 wherein the light sensor comprises an optical bridge (90, 190) and a light emitter (70, 170) that projects light onto the optical bridge and the optical bridge generates the output signal which corresponds to the intensity of the projected light across the optical bridge.

59. The sensor according to claim 58 wherein the optical bridge comprises multiple spaced photosensitive cells (98, 100, 198, 200).

60. The sensor according to claim 58 wherein the light emitter is operably coupled to the moveable object wherein the movement of the moveable object correspondingly moves the light emitter to thereby move the location where the projected light contacts the optical bridge to change the light intensity seen by each photosensitive cell.

61. The sensor according to claim 58 and further comprising a light diffuser panel (94) disposed between the light emitter and the optical bridge.

62. The sensor according to claim 58 wherein the light emitter comprises a light source (78, 178) and a wall with a diffraction slit (176) disposed between the light source and the optical bridge so that the light projected from the light source passes through the diffraction slit and is diffracted prior to reaching the optical bridge.

63. The sensor according to claim 62 and further comprising a collimating lens (180) disposed between the light source and the diffraction slit.

64. The sensor according to claim 58 and further comprising fresnel lens (180) disposed between the light emitter and the optical bridge and the fresnel lens is operably connected to the moveable object wherein the movement of the moveable object correspondingly moves the fresnel lens.

65. The sensor according to claim 55 wherein the transducer sensor is a variable-capacitance capacitor (344) operably coupled to the movable object so that the movement of the moveable object results in a corresponding change in the capacitance of the variable capacitor.

66. The sensor according to claim 65 wherein the variable-capacitance capacitor comprises a capacitor bridge circuit (352, 354) that generates the output signal.

67. The sensor according to claim 66 wherein the capacitor bridge circuit comprises first and second capacitors (352, 354) having variable capacitance and the output signal corresponds to the capacitance differential between the first and second capacitors.

68. The sensor according to claim 67 wherein the capacitor bridge comprises first and second electrically isolated plates (348) and a moveable plate (346) having a portion overlying each of the first and second electrically isolated plates and operably coupled to the moveable object such that the movement of the moveable object results in a corresponding movement of the moveable plate to change the size of the portion of the moveable plate overlying each of the first and second plates to thereby vary the capacitance of each capacitor.

69. The sensor according to claim 55 wherein the transducer sensor is a variable resistor (444).

70. The sensor according to claim 69 wherein the variable resistor comprises a flexible strip (444) that changes in resistance as the strip is bent.

71. The sensor according to claim 70 and further comprising a flexible support (442) on which the flexible strip is mounted.

72. The sensor according to claim 71 wherein the flexible support is spring metal.

73. The sensor according to claim 72 wherein the flexible support has a preformed shape to control the bending profile of the flexible strip.

74. The sensor according to claim 73 wherein the preformed shape bell-shaped curve when viewed in profile.

75. The sensor according to claim 73 wherein the preformed shape is a helix.