Check valve and braking system using the same

1. A check valve comprising:

a case member having an entrance-side fluid passage where fluid flows in, an exit-side fluid passage where fluid flows out, and a valve seat disposed in a downstream end of the entrance-side fluid passage;

a pipeline disposed in a housing, the pipeline being separated into a downstream side pipeline of the check valve and an upstream side pipeline of the check valve by the case member;

a valve member that opens and closes a passage between the entrance-side fluid passage and the exit-side fluid passages by touching and separating from the valve seat, and is energized in a valve opening direction by a pressure of the fluid from the entrance-side fluid passage; and

a spring that energizes the valve member in a valve closing direction; wherein,

the check valve opens when the energization force in the valve opening direction due to the pressure exceeds the energization force in the valve closing direction due to the spring; wherein,

the valve member has a piston part that reciprocates, and a valve part that is disposed in the valve seat side and touches and separates to the valve seat;

the case member has a piston accommodation cylinder part that accommodates the piston part reciprocatably;

the piston part has a valve part accommodating recess that accommodates a part of the valve part;

the valve part is disposed in the valve part accommodating recess movably relative to the piston part, and is urged against a wall surface of the valve part accommodating recess by a pressure of the fluid from the entrance-side fluid passage;

among the valve part accommodating recess, an anti-valve seat side accommodation space formed between a surface in an anti-valve seat side of the valve part and a wall surface of the valve part accommodating recess communicates to the exit side fluid passage.

a damper chamber is formed by the valve member and the case member in an anti-valve seat side of the valve member, the damper chamber generates damping force;

the anti-valve seat side accommodation space communicates with the exit side fluid passage through a piston part communicating slot formed in the wall surface of the valve part accommodating recess;

the valve part accommodating recess has a tapered surface, and the valve part is contactable to the tapered surface,

the anti-valve seat side accommodation space is formed between the piston part and the valve part; and

the piston accommodation cylinder part is formed coaxially with the entrance-side fluid passage, and only a single through hole extending in a radial direction is formed in the piston accommodation cylinder part.

2. The check valve according to claim 1 , wherein;

the depth of the valve part accommodating recess is configured so that the valve part does not detach from the valve part accommodating recess when the piston part is positioned where most distant from the valve seat.