A piston pump includes: a sleeve housing which is provided with a discharge hole and defines a bore; a piston which has an inlet flow passage for drawing oil into the bore and is reciprocally movably inserted into the bore; an inlet valve which is configured to open/close the inlet flow passage; an outlet valve cover which is coupled to the sleeve housing to surround a portion at which the discharge hole is formed; an outlet valve which is configured to open/close the discharge hole; and a sealing member which is interposed between the sleeve housing and the piston to provide a sealing therebetween. The sealing member is provided with a separation prevention protrusion against which the piston is blocked to prevent a separation of the piston.

Embodiments of a valve assembly and a plumbing system incorporating the same are provided herein. In some embodiments, a valve assembly for use with an enclosed environment includes a housing having an interior volume, an inlet disposed at a first end of the housing and fluidly coupled to an environment surrounding the housing, and an outlet disposed at a second end of the housing opposite the first end and fluidly coupled to the enclosed environment; a first valve having a first valve seat and a first sealing member at least partially extending through a first opening in the first valve seat in a closed position; and a second valve disposed beneath the first valve and having a second valve seat and a second sealing member at least partially extending through a second opening in the second valve seat in a closed position.

A valve assembly for a fuel tank system including a fuel tank having a fuel tank outlet and a purge canister includes a main valve and a safety check valve. The main valve can be configured to move from a closed position to an open position. The main valve can have a main valve first port fluidly coupled to the outlet of the fuel tank and a main valve second port fluidly connected to the purge canister. The safety check valve can be configured to move from an open position to a closed position upon a pressure drop at the fuel tank outlet exceeding a predetermined threshold. The safety check valve can have a safety check valve first port fluidly coupled to the outlet of the fuel tank and a safety check valve second port fluidly coupled to the purge canister.

The security unit ensures, by blocking the hydraulic flow, that the rod of a cylinder is held in position. It includes two preferably twinned isolation devices, each mounted on one of the hydraulic lines supplying fluid to a chamber of the cylinder. Each isolation device includes two series-connected ball-check valves allowing the flow in the direction of inlet of the fluid into the respective chamber; and a longitudinal, separate rod, inserted between the balls but not linked thereto, and capable of being slidably guided towards each of the balls and driving same. The rod is too short to contact both balls simultaneously when the two valves are closed; but it is sufficiently long to push the ball of the second valve, thereby causing it to open, when it slides under the pushing action of the ball of the first valve upon the latter being controlled to be opened.

A check valve is disclosed. The check valve, which is installed in a modulator block of a brake system having a flow path forming a hydraulic circuit, may include: a sleeve housing whose both ends open, the sleeve housing having a discharge flow path, wherein at least one outlet is formed in the discharge flow path; a pair of adaptors respectively coupled with both open ends of the sleeve housing, wherein in one end of each adaptor, an inlet connected to a flow path of the modulator block is formed, and in the other end of the adaptor, a valve seat connected to the discharge flow path is formed; an elastic member disposed in the discharge flow path; and a pair of opening and closing members respectively supported on both ends of the elastic member, and disposed to selectively contact each valve seat of the pair of adaptors.

A fuel tank system constructed in accordance to one example of the present disclosure includes a fuel tank, a purge canister and a valve assembly. The valve assembly can be fluidly coupled between the fuel tank and the purge canister. The valve assembly can include a main valve and a safety check valve. The main valve can have a main valve first port fluidly coupled to an outlet of the fuel tank and a main valve second port fluidly connected to the purge canister. The safety check valve can be configured to move from an open position to a closed position upon a pressure drop at the fuel tank outlet exceeding a predetermined threshold. The safety check valve can have a safety check valve first port fluidly coupled to the outlet of the fuel tank and a safety check valve second port fluidly coupled to the purge canister.

A check valve supplies fluid to a system and includes a fluid barrier protects the sealing elements and surfaces of the check valve preventing degradation from any backflow of gas and debris from the system to which fluid is supplied.

An object of the present invention is to provide a simple-structured tensioner capable of consistently exhibiting the check valve function irrespective of the form of oil supply passages. The tensioner includes a plunger, a housing, a biasing unit, an oil supply passage, and a check valve. The check valve includes a plurality of valve members and a ball seat member. The ball seat member includes a plurality of oil passages and a plurality of seat parts. The check valve further includes a passage forming member having an oil inlet disposed between the plurality of oil passages and the oil supply passage.

The present invention proposes a valve assembly in which the flow direction of a fluid is controlled according to a tilt angle and a large amount of fluid can be moved. The valve assembly of the present invention consists of: a valve body (10) provided thereinside with an inner passage through which a fluid can pass, and having a pair of access ports (12, 14) which are formed at positions opposite to each other to enable the fluid to flow in and out and are relatively long in the horizontal direction compared to the longitudinal direction, and a pair of seating portions (12a, 14a) which are respectively formed in an inner portion of the pair of access ports; a pair of connection portions (32, 34) which communicate with the pair of access ports and are connected so that the fluid can flow between the inside and the outside of the valve body; and one or a pair of check balls or check rollers (16A, 16B) for controlling the flow of the fluid from the inside of the valve body to the connection portions by being seated in or spaced from the seating portions of the valve body. Also, a stopper enables the fluid to flow within a predetermined range at the access ports where the check balls or check rollers have been assigned. Accordingly, one check ball or check valve can open and close only an assigned access port so that the flow direction of the fluid can be quickly and accurately controlled.

Embodiments of a valve assembly and a plumbing system incorporating the same are provided herein. In some embodiments, a valve assembly for use with an enclosed environment includes a housing having an interior volume, an inlet disposed at a first end of the housing and fluidly coupled to an environment surrounding the housing, and an outlet disposed at a second end of the housing opposite the first end and fluidly coupled to the enclosed environment; a first valve having a first valve seat and a first sealing member at least partially extending through a first opening in the first valve seat in a closed position; and a second valve disposed beneath the first valve and having a second valve seat and a second sealing member at least partially extending through a second opening in the second valve seat in a closed position.