Damping force control type shock absorber
AssigneeHitachi Automotive Systems, Ltd.
InventorsHiroyuki Yabe, Yohei Katayama, Takashi Nezu
Life of this patent
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Abstract
During either of the extension and compression strokes, hydraulic liquid flows from a cylinder upper chamber into a reservoir through an annular passage and a damping force control mechanism, and a damping force is generated by the damping force control mechanism. The check valve is provided with a sub-check valve in parallel thereto, which opens in a very low piston speed region to allow the hydraulic liquid to flow through an orifice passage. These check valves are opened successively as the piston speed increases, thereby generating a sufficiently small damping force in the very low piston speed region during the compression stroke of the piston rod, and obtaining a moderate damping force when the piston speed increases.
Claims6
A damping force control type shock absorber comprising:
- a cylinder including a hydraulic liquid sealed therein;
- a reservoir including the hydraulic liquid and a gas sealed therein;
- a piston slidably fitted in the cylinder to divide an interior of the cylinder into a first chamber and a second chamber;
- a piston rod connected at one end thereof to the piston and including an another end extended to an outside through the first chamber;
- a base valve for dividing the second chamber and the reservoir from each other;
- a first check valve provided in the piston to allow a flow of hydraulic liquid from the second chamber toward the first chamber;
- a second check valve provided in the base valve to allow a flow of hydraulic liquid from the reservoir toward the second chamber;
- a passage for connecting the first chamber and the reservoir;
- and
- a damping force control mechanism for adjusting damping force by controlling a flow of hydraulic liquid in the passage;
- an orifice passage provided in parallel to at least one of the first check valve and the second check valve;
- and
- a sub-check valve provided in the orifice passage, the sub-check valve being configured to open at a lower pressure than the check valve to which the orifice passage is provided in parallel and to allow a flow of hydraulic liquid in a same direction as the check valve,
- wherein the damping force control mechanism is a pilot-type control valve, and
- wherein the piston speeds at which the first check valve and the second check valve open, respectively, are lower than a piston speed at which the pilot-type control valve opens.
Dependencies are inferred from the claim text.