Damping force control type shock absorber
View Patent ↗The flow of hydraulic fluid induced by sliding movement of a piston in a cylinder is controlled by a pilot-type main valve and a pilot valve, which is a pressure control valve, thereby generating damping force. By thrust from a solenoid actuator, the valve-opening pressure of the pilot valve is controlled, and the pressure in a pilot chamber is also controlled to control the valve-opening pressure of the main valve. When there is a failure, a valve body of the pilot valve is retracted to abut against a fail-safe disk by spring force of a valve spring. Thus, damping force is generated by the fail-safe disk at the downstream side of the pilot valve, and the valve-opening pressure of the main valve is also controlled by the fail-safe disk to obtain an appropriate damping force.
1. A damping force control type shock absorber comprising:
a cylinder having a fluid sealed therein;
a piston slidably fitted in the cylinder;
a piston rod connected at one end thereof to the piston, an other end of the piston rod extending to an outside of the cylinder;
a main valve adapted to generate damping force by controlling a flow of fluid induced by sliding movement of the piston in the cylinder;
a pilot chamber adapted to apply a pressure therein to the main valve in a direction for closing the main valve;
an inlet passage adapted to introduce the fluid into the pilot chamber;
a pilot passage adapted to communicate between the pilot chamber and a downstream side of the main valve;
a control valve provided in the pilot passage to open and close the pilot passage, the control valve having a valve body urged by an urging member in a direction for opening the pilot passage, and an actuator adapted to move the valve body in a direction for closing the pilot passage by thrust from a solenoid; and
a fail-safe valve provided in the pilot passage at a downstream side of the valve body, the fail-safe valve comprising an annular disk valve having an outer peripheral portion that is capable of being restrained,
the fail-safe valve adapted to close the pilot passage by the valve body abutting against an inner peripheral portion of the fail-safe valve, when the valve body is urged by the urging member and moves in the direction for opening the pilot passage,
the inner peripheral portion of the fail-safe valve adapted to be spaced apart from the valve body to open the pilot passage when the pressure in the pilot chamber reaches a predetermined pressure.
2. The damping force control type shock absorber of claim 1 , wherein an orifice is formed in at least one of the fail-safe valve and the valve body abuttable against the fail-safe valve.
3. The damping force control type shock absorber of claim 2 , wherein the control valve is a pressure control valve opening when the pressure in the pilot passage reaches a predetermined pressure.
4. The damping force control type shock absorber of claim 2 , wherein the valve body of the control valve is provided in a valve chamber, the valve chamber opening at one end thereof into the pilot chamber, an other end of the valve chamber opening downstream of the fail-safe valve.
5. The damping force control type shock absorber of claim 1 , wherein the valve body of the control valve is provided in a valve chamber, the valve chamber opening at one end thereof into the pilot chamber, an other end of the valve chamber opening downstream of the fail-safe valve.
6. The damping force control type shock absorber of claim 5 , wherein one end of the valve chamber is selectively opened and closed by one end of the valve body, an other end of the valve chamber being selectively opened and closed by both the fail-safe valve and an other end of the valve body.
7. The damping force control type shock absorber of claim 1 , wherein the control valve is a pressure control valve opening when the pressure in the pilot passage reaches a predetermined pressure.
8. The damping force control type shock absorber of claim 7 , wherein the valve body of the control valve is provided in a valve chamber, the valve chamber opening at one end thereof into the pilot chamber, an other end of the valve chamber opening downstream of the fail-safe valve.
9. The damping force control type shock absorber of claim 1 , wherein the other end of the valve body is provided with an annular seat portion abuttable against the fail-safe valve.