Patent ID: 8794403

Claim:
A damping force generating mechanism for a hydraulic shock absorber in which the shock absorber includes a cylinder, a piston that slides within the cylinder and defines a first fluid chamber and a second fluid chamber in the cylinder, and a piston rod that is joined to the piston so as to project from the cylinder in an axial direction, the damping force generating mechanism comprising: a port formed in the piston to cause a fluid to flow from the first fluid chamber to the second fluid chamber; a damping valve that closes the port on the second fluid chamber side; a passage that connects the first fluid chamber to the port; a throttle valve that reduces a flow sectional area of the passage based on a pressure of the first fluid chamber; a pressure chamber that exerts an oppositely oriented pressure to the pressure of the first fluid chamber on the throttle valve; a plate spring that biases the throttle valve in an opposite direction to the pressure of the first fluid chamber; and a connecting passage that is formed in the piston rod and connects the pressure chamber to the second fluid chamber without passing through the damping valve; wherein the throttle valve includes a first pressure-receiving surface that receives a pressure of the first fluid chamber and a second pressure-receiving surface that receives a pressure of the pressure chamber in an opposite direction to the first pressure-receiving surface; wherein the pressure chamber is formed in the first fluid chamber in a state isolated permanently therefrom, irrespective of a stroke speed of the piston; and wherein the throttle valve is configured to reduce a flow cross-sectional area when a differential pressure between the first fluid chamber and the pressure chamber exceeds a biasing force of the plate spring.