A linear compressor is provided that may include a shell in which a discharge port may be provided, a cylinder disposed in the shell to define a compression space for a refrigerant, a piston disposed to be reciprocated in an axial direction within the cylinder, a discharge valve disposed on or at one side of the cylinder to selectively discharge the refrigerant compressed in the compression space, a valve spring coupled to the discharge valve to provide a restoring force, and a stopper coupled to the valve spring to restrict deformation of the valve spring. The stopper may include a guide recessed in a direction in which the valve spring is deformed to reduce an impulse between the stopper and the valve spring.

A linear compressor is provided that may include a shell in which a discharge port is provided, a cylinder disposed in the shell to define a compression space for a refrigerant, a piston disposed to be reciprocated in an axial direction within the cylinder, a discharge valve disposed on or at one side of the cylinder to selectively discharge the refrigerant compressed in the compression space, the discharge valve including an insertion protrusion, and a valve spring coupled to the discharge valve to provide a restoring force to the discharge valve. The valve spring may include a spring body having a central portion defined at a portion corresponding to a center of the cylinder, and an insertion hole defined in the spring body. The insertion hole may be coupled to the insertion protrusion of the discharge valve. The central portion of the spring body may be spaced apart from a central portion of the insertion hole.

A fluid end includes a casing that defines a work space that includes a cross bore space and an inlet bore centered on an inlet bore axis and intersecting the cross bore space, the intersection of the inlet bore and the cross bore space at least partially defined by a first curved edge. An outlet bore is centered on an outlet bore axis and intersects the cross bore space, a plunger bore is centered on a plunger axis and intersects the cross bore space, a first angled surface is defined by the first curved edge, and a second angled surface is disposed adjacent the first angled surface such that the first and second angled surfaces cooperate to define a V-shaped groove having an exterior angle between 180 degrees and 270 degrees. An inlet spring retainer includes a first engagement portion, is orientable in a first orientation in which the retainer is movable from the inlet bore to the plunger bore and a second orientation in which the retainer engages the first and second angled surfaces to inhibit movement of the retainer.

Valves for relieving pressure from high-pressure fluid systems have a valve fitting and a valve actuator. The pressure relief valve is normally shut and is adapted to open at a relief fluid pressure. It comprises a valve fitting and an actuator. The actuator has a valve stem, a spring, and an electromagnet. The stem is coupled to a valve body and mounted for linear reciprocation. The spring applies a mechanical force that biases the stem to place the valve in a normally shut state, but allows the valve to open at a first fluid pressure below the relief pressure. The electromagnet applies a magnetic force that, together with the mechanical force, holds the valve in an operationally shut state at a second fluid pressure above the relief pressure. The valve may be opened at fluid pressures above the first fluid pressure by de-energizing the electromagnet at the relief pressure.

A fluid flow throttle valve that keeps the pressure of a fluid flow pumped into a system by a high-pressure pump constant and that is particularly suitable as a reject valve for maintaining the system pressure of a reverse osmosis device at a pressure level of <20 bar. The flow pressure is regulated by a spring-actuated cone that is partially within the outflow channel of the throttle valve at any given time. A motion restrictor is supported to the wider end of the cone such that in its lowest position, the cone permits a bypass flow of a predetermined volume up to the target pressure of the system. As the flow volume increases further and the cone rises as a result, the force exerted on the restrictor member by the flow pressure contributes to preventing the valve from closing.