| 摘要 |
An adjustable damping force hydraulic shock absorber comprising a cylinder, a piston partitioning the interior of the cylinder into two chambers, a plurality of passages through which working fluid contained in the cylinder flows when the piston axially moves in the cylinder, a damping force generating mechanism for generating a damping force by controlling the flow of the working fluid through the passages, and a damping force regulating valve capable of regulating the damping force by opening or closing one specific passage of the plurality of passages. The present invention provides a shock absorber of the aforementioned type which is characterized in that the damping force regulating valve comprises an axially movable valve element having one end in contact with a valve seat formed in the specific passage when the valve element is seated on the valve seat to block the flow of the working fluid through the specific passage between the two chambers, the valve element being such designed as to define a space on the side of the other end thereof, the space communicating with the side of the one end, a plunger attached to the other end of the valve element, the plunger being formed of a magnetic material, a solenoid axially slidably receiving the plunger, and capable of axially moving the plunger when energized, and a permanent magnet for holding the plunger at a position to which the plunger has been moved, and that the valve element is formed so that the remainder of a subtraction of the pressure receiving area thereof receiving the pressure in one of the chambers in an opening direction from the pressure receiving area thereof receiving the pressure in the same chamber in a closing direction is zero or a positive value, and the remainder of a subtraction of the pressure receiving area thereof receiving the pressure in the other chamber in an opneing direction from the pressure receiving area thereof receiving the pressure in the same chamber in a closing direction is zero or a positive value, when the valve element is seated on the valve seat.
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