Hydraulic control device for active suspension system

• US 5,366,236 A
• Filed: 08/06/1992
• Issued: 11/22/1994
• Est. Priority Date: 08/06/1991
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Noro, Yoshiaki, Ohsaki, Seiji, Kuriki, Nobuharu, Shibue, Hideaki
• Primary Examiner(s): BASINGER, SHERMAN D
• Application Number:
  US07/925,991
• Time in Patent Office: 838 Days
• Field of Search: 280/707, 280/714, 280/709
• US Class Current: 280/5.514
• CPC Class Codes: B60G 17/0185 for failure detection
• CPC Class Codes: B60G 2202/413 Hydraulic actuator
• CPC Class Codes: B60G 2202/414 using electrohydraulic valves
• CPC Class Codes: B60G 2400/25 Stroke; Height; Displacement
• CPC Class Codes: B60G 2400/60 Load
• CPC Class Codes: B60G 2400/61 Load distribution
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/182 Active control means
• CPC Class Codes: F16F 9/003 Dampers characterised by having pressure absorbing means other than gas, e.g. sponge rubber

Abstract

In an active vehicle suspension system employing a double acting type single rod hydraulic linear actuator in which a piston is provided with two pressure receiving surfaces facing two different piston chambers defined by the piston received in a cylinder and having different areas, even when the line pressure of the hydraulic oil passage is lost, the height of the vehicle body can be maintained at a fixed level and a sudden change of the height of the vehicle body can be avoided by providing a hydraulic control device which appropriately controls the pressures of the upper and lower chambers so as to be inversely proportional to the areas of the corresponding pressure receiving surfaces as the pressure supplied to the hydraulic actuator is reduced.

Claims

1. A hydraulic control device for an active suspension system employing a linear hydraulic cylinder including a piston connected in parallel with a spring between a wheel and a vehicle body, said piston having two pressure receiving surfaces of different areas, comprising:

a pressure source; and

pressure relieving means for reducing pressures in two pressure chambers separated by said piston in said hydraulic cylinder so as to balance upward and downward thrusts acting upon said piston as a level of hydraulic pressure supplied to said hydraulic cylinder is reduced.

6. A hydraulic control device according to claim 1, wherein said pressure relieving means reduces the pressures of said two pressure chambers to a level near atmospheric pressure.

2. A hydraulic control device for an active suspension system employing a linear hydraulic actuator including a piston connected in parallel with a spring between a wheel and a vehicle body, said piston having first and second pressure receiving surfaces of different areas facing first and second oil chambers defined and separated by said piston in said hydraulic actuator, said first pressure receiving surface being smaller than said second pressure receiving surface said control device comprising:

a pressure source;

a first oil passage connected between said pressure source and said first chamber;

a pressure control valve connected between said first oil passage and said second chamber;

a second oil passage connected to said pressure control valve for selectively relieving pressure through said pressure control valve to a pressure sink;

a bypass passage connected between said first and second oil passages provided with a switch valve for selectively allowing at least a limited communication between said first and second chambers; and

a balancing valve for relieving pressure from said second chamber at a rate depending on a pressure in said first chamber.

3. A hydraulic control device for an active suspension system according to claim 2, wherein said balance valve is provided with a preset pressure defining means for maintaining pressure in said second oil passage at a level slightly higher than the atmospheric pressure.

4. A hydraulic control device for an active suspension system according to claim 3, wherein the first oil passage is provided with a low pressure accumulator having an operating pressure range covering said pressure level slightly higher than the atmospheric pressure.

5. A hydraulic control device for an active suspension system according to claim 2, wherein said bypass passage is provided with a storage container containing actuating oil by an amount substantially corresponding to an effective capacity of said hydraulic actuator.