Shock absorber

A shock absorber comprising:

• a cylinder sealingly containing hydraulic fluid;
• a piston slidably and fittedly inserted in the cylinder;
• a piston rod coupled to the piston, and extending out of the cylinder;
• and
• a damping force generation mechanism configured to generate a damping force by controlling a flow of the hydraulic fluid generated by a sliding movement of the piston,
• wherein the damping force generation mechanism includes a main valve configured to generate the damping force, a back pressure chamber configured to apply a back pressure in a direction for closing the main valve, an introduction passage configured to guide the back pressure into the back pressure chamber, a discharge passage configured to discharge the back pressure in the back pressure chamber, and a control valve disposed in the discharge passage,
• wherein the control valve includes a valve body disposed in the discharge passage, a valve seat, an actuator configured to generate a force for moving the valve body toward the valve seat according to a current, and a spring unit configured to bias the valve body in a direction opposite from a direction in which the valve body is moved by the actuator,
• wherein the spring unit includes one member configured to act on the valve body throughout a whole range of the movement of the valve body, and a limiting member configured to limit a deflection of a part of the spring member by abutting a predetermined portion of the spring member against the limiting member with a predetermined deflection of the spring member when the valve body is moved toward the valve seat, and
• wherein the spring member has a spring constant acting on the valve body due to a deflection of another part of the spring member at which a deflection is not limited, after limitation of the deflection of the spring member by the limiting member, which is higher than that of the spring member before limiting the deflection of the spring member.