Check valve for brake system

1. A check valve for a brake system, comprising:

a valve seat configured to form an oil passage thereinside;

an opening/closing member configured to open and close the oil passage inside the valve seat;

an elastic member having one end elastically supporting the opening/closing member;

a valve housing configured to support the other end of the elastic member and coupled to the valve seat; and

a plunger that is accommodated in the oil passage and flows according to a flow of fluid generated during operation of the brake system,

wherein

the oil passage comprises

a first oil passage that forms an inlet which fluid flows in,

a second oil passage that forms an outlet which fluid flows out, the plunger being provided on an upstream side of the second oil passage, and

a neck passage between the first oil passage and the second oil passage, the neck passage being narrower than the second oil passage,

first and second opposite ends of the plunger are restrained by the neck passage and the opening/closing member, respectively, and

the oil passage includes an empty space between an outer surface of the plunger and an inner surface of the second oil passage, and the empty space is open.

2. The check valve of claim 1 , wherein

a length of the plunger is smaller than or equal to a length of the second oil passage.

3. The check valve of claim 1 , wherein

the plunger is configured to flow in a vertical direction of the oil passage.

4. The check valve of claim 1 , wherein

the plunger is provided in a form of a polyhedral prism.

5. The check valve of claim 4 , wherein

the plunger is provided in a form of a triangular prism having a triangular horizontal cross-section.

6. A check valve for a brake system, comprising:

a valve seat configured to form an oil passage thereinside;

an opening/closing member configured to open and close the oil passage inside the valve seat;

an elastic member having one end elastically supporting the opening/closing member;

a valve housing configured to support the other end of the elastic member and coupled to the valve seat; and

a plunger configured to be flowably accommodated in the oil passage and to rise when a flow of fluid occurs, to prevent the opening/closing member from descending while in contact with the opening/closing member for reducing a stroke of the opening/closing member,

wherein

the oil passage comprises

a first oil passage that forms an inlet which fluid flows in,

a second oil passage that forms an outlet which fluid flows out, the plunger being provided on an upstream side of the second oil passage, and

a neck passage between the first oil passage and the second oil passage, the neck passage being narrower than the second oil passage,

first and second opposite ends of the plunger are restrained by the neck passage and the opening/closing member, respectively, and

the oil passage includes an empty space between an outer surface of the plunger and an inner surface of the second oil passage, and the empty space is open.

7. The check valve of claim 6 , wherein

when the plunger is in contact with the opening/closing member according to the flow of fluid, at least a part of the plunger is accommodated in the oil passage.

8. The check valve of claim 6 , wherein

the plunger is configured to flow in a vertical direction of the oil passage.

9. The check valve of claim 8 , wherein

the plunger is provided in a form of a polyhedral prism.

10. The check valve of claim 6 , wherein

a length of the plunger is smaller than or equal to a length of the second oil passage.

11. The check valve of claim 6 , wherein

the plunger is provided in a form of a triangular prism.