| United States Patent | 7,240,906 |
| Klees | July 10, 2007 |
Hydro-pneumatic suspension system
A hydro-pneumatic suspension system for a vehicle includes hydraulic struts selectively interconnected, in on-road and off-road configurations, to obviate the need for conventional shocks and springs. In the on-road configuration, the hydraulic struts are linked cross-vehicle with multiple accumulators in the circuit for increased on-road roll stiffness. In the off-road configuration, the hydraulic struts are self-linked, with fewer accumulators, to maximize flexibility and articulation of the system. The system also includes a hydraulic supply to selectively raise and lower the vehicle for the off-road and on-road configurations, respectively. In a further configuration, the roll stiffness and articulation of the suspension system is configured solely by the selective connection of accumulators to the hydraulic suspension circuit.
| Inventors: | Klees; Gerard (Oxford, MI) |
| Assignee: | DaimlerChrysler Corporation (Auburn Hills, MI) |
| Appl. No.: | 10/728,040 |
| Filed: | December 4, 2003 |
| Current U.S. Class: | 280/5.502 ; 280/5.507 |
| Current International Class: | B60G 21/00 (20060101) |
| Field of Search: | 280/5.514,5.5,5.502,5.504,5.506,5.507,5.512,5.515,5.519,6.157,124.159,124.161,124.106,124.107 |
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Assistant Examiner: Gooden, Jr.; Barry
Attorney, Agent or Firm:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 60/430,898, filed Dec. 4, 2002, entitled "Hydro-Pneumatic Suspension System."
What is claimed is:
1. A hydro-pneumatic suspension system having a right side hydro-pneumatic strut cross-coupled to a left side hydro-pneumatic strut such that an upper chamber of the right side strut is fluidly connected to a lower chamber of the left side strut and an upper chamber of the left side strut is fluidly connected to a lower chamber of the right side strut, the suspension system further comprising: a first accumulator fluidly connected with the upper chamber of the right side strut; a second accumulator selectively fluidly connected with the upper chamber of the right side strut by a spring-rate valve; a hydraulic supply selectively fluidly connected with the right side strut by a ride-height valve; and a suspension control system adapted to control the spring-raze valve, hydraulic pump and ride-height valve to set the suspension system in one of an on-road configuration and an off-road configuration, wherein the suspension control system opens the ride-height valve to fluidly connect the hydraulic supply to the right side strut to raise the overall height of the vehicle, and closes the ride-height valve upon reaching a selected vehicle height.
2. The suspension system of claim 1 wherein the cross-flow valve selectively fluidly connects the upper chamber of the right side strut with the lower chamber of the left side strut, the system further comprising a second cross-flow valve selectively fluidly connecting the upper chamber of the left side strut with the lower chamber of the right side strut.
3. The suspension system of claim 1, further comprising a third accumulator fluidly connected with the upper chamber of the left side strut and a fourth accumulator selectively fluidly connected with the upper chamber of the left side strut by a second spring-rate valve.
4. The suspension system of claim 1, further comprising a flow-restricting orifice fluidly connecting the first and second accumulators with the right side strut, and a second flow-restricting orifice fluidly connecting the third and fourth accumulators with the left side strut.
5. In a vehicle having a hydro-pneumatic suspension system, the suspension system having a right side hydro-pneumatic strut cross-coupled to a corresponding left side hydra-pneumatic strut such that an upper chamber of the right side strut is fluidly connected to a lower chamber of the left side strut and an upper chamber of the left side strut is fluidly connected to a lower chamber of the right side strut, the suspension system further comprising: a cross-flow valve for selectively fluidly connecting the right side strut with the left side strut; an articulation valve for selectively fluidly connecting the upper chamber of the right side strut with the lower chamber of the right side strut; a first accumulator fluidly connected with the upper chamber of the right side strut; a second accumulator selectively fluidly connected with the upper chamber of the right side strut by a spring-rate valve; a hydraulic simply selectively fluidly connected with the right side and left side struts by a ride-height valve; and a suspension control system adapted to control the cross-flow valve, articulation valve, ride-height valve and spring-rate valve to set the suspension system in one of an on-road configuration and an off-road configuration and wherein the suspension control system opens the ride-height valve and fluidly connects the hydraulic supply to raise the overall height of the vehicle.
6. The suspension system of claim 5, wherein the suspension control system further closes the cross-flow valve and the spring-rate valve, and opens the articulation valve to set the suspension system in the off-road configuration.
7. The suspension system of claim 5, wherein the cross-flow valve selectively fluidly connects the upper chamber of the right side strut with the lower chamber of the left side strut, the system further comprising a second cross-flow valve selectively fluidly connecting the upper chamber of the left side strut with the lower chamber of the right side strut.
8. The suspension system of claim 5, further comprising a third accumulator fluidly connected with the upper chamber of the left side strut and a fourth accumulator selectively fluidly connected with the upper chamber of the left side strut by a second spring-rate valve.
9. The suspension system of claim 8, further comprising a flow-restricting orifice fluidly connecting the first and second accumulators with the right side strut, and a second flow-restricting orifice fluidly connecting the third and fourth accumulators with the left side strut.
10. A suspension system comprising: a right side hydro-pneumatic strut cross-coupled to a left side hydro-pneumatic strut such that an upper chamber of the right side strut is fluidly connected to a lower chamber of the left side strut and an upper chamber of the left side strut is fluidly connected to a lower chamber of the right side strut; a first accumulator fluidly connected with the upper chamber of the right side strut; a second accumulator selectively fluidly connected with the upper chamber of the right side strut by a spring-rate valve; a hydraulic supply selectively fluidly connected with the right side strut by a ride-height valve; and a suspension control system adapted to control the spring-rate valve, hydraulic pump and ride-height valve to set the suspension system in one of an on-road configuration and an off-road configuration; wherein the suspension control system opens the ride-height valve to connect the hydraulic supply to the right side strut to raise the overall height of the vehicle when converting from the on-road configuration to the off-road configuration.
11. The suspension system of claim 10 further comprising: a first cross-flow valve for selectively fluidly connecting the right side strut to the left side strut; and a second cross-flow valve for selectively fluidly connecting the left side strut to the right side strut; a conduit and an articulation valve for selectively fluidly connecting the upper chamber of the right side strut with the lower chamber of the right side strut; wherein the suspension control system is arranged to set the suspension system in the off-road configuration by closing the ride-height valve, the first and second cross-flow valves and the spring rate valve, and opening the articulation valve; and wherein the suspension control system is arranged to set the suspension in the on-road configuration by closing the articulation valve and opening the cross-flow valve and the spring-rate valve.
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