A plunger pump, including: a tubular cylinder that has an internal space communicating with inlet and outlet flow paths; and a piston that is movable along an axis of the cylinder, wherein a head of the piston includes, on an outer peripheral surface thereof, a sealing portion that is slidable against an inner peripheral surface of the cylinder, which includes a body tubular portion wherein the head is arranged during normal use, and a cleaning tubular portion wherein the head is arranged during cleaning, an inner peripheral surface of the cleaning tubular portion has an inner diameter equal to that of an inner peripheral surface of the body tubular portion, the cleaning tubular portion includes, on the inner peripheral surface thereof, at least one cleaning liquid circulation groove that is configured by a through hole or recess, and the cleaning liquid circulation groove extends obliquely with respect to the axis.

A pump system includes a housing, a lubricant system, and control circuitry. The housing includes a pump chamber defined by the housing and a throat seal. The lubricant system includes a lubricant pump, a lubricant gallery defined within the housing of the main pump, and a lubricant circuit fluidly connecting the lubricant pump and the lubricant gallery. The throat seal is disposed adjacent to and between the pump chamber and the lubricant gallery. The control circuitry is configured to cause the lubricant pump to pump a purge volume of lubricant through the lubricant system, cause the lubricant pump to stop pumping for a first time period after the lubricant pump has pumped the purge volume, and cause the lubricant pump to pump the purge volume of lubricant through the lubricant system after the first time period.

An air stop sheet of a piston of a cylinder, the piston is accommodated in an air compressor, and an air stop sheet is accommodated on a head of the piston. The air stop sheet includes a bending section having a positioning zone and an acting zone and configured to be a boundary line of the acting zone and the positioning zone. The acting zone backing the cylinder turns on relative to the plane of the head at an open angle θ, thus producing an air flowing space. A piston rod extends downward from the head and includes a cavity, an air conduit, a column, and a spring configured to abut against the acting zone of the air stop sheet. The air stop sheet is pushed by the spring to turn on at an open angle θ, and the air conduit and the air channel communicate with atmosphere.

A compressor is disclosed. A compressor according to the present discloser includes a piston structure which has a guide member reciprocating inside a cylinder in an axial direction, and a magnet frame which supports a mover moving together with the piston structure, in which the piston structure includes the guide member, a mount member connected to the magnet frame, and an elastic member provided between the guide member and the mount member and capable of elastic deformation.

A pump module with a casing having at least one pump piston is mounted in a reciprocatingly movable manner and may include a sealing element which, in pumping operation, abuts in a sealing manner against a cylinder. An embodiment of a pump module, which is easy to produce and can be disinfected or sterilized in a simple manner, includes a pump piston that can be fixated in a parking position in which the sealing element does not abut against the cylinder.

The invention relates to a piston pump, in particular for injection systems for motorized two-wheeled vehicles and/or for motorized three-wheeled vehicles, having a compression chamber, a piston, an inlet valve, and an outlet valve. A fluid can flow into the compression chamber via the inlet valve, and the fluid can flow out of the compression chamber via the outlet valve. A region in the form of a channel, which is arranged fluidically upstream of the outlet valve, in particular directly upstream of the outlet valve, has a cross-section which is reduced compared to a compression chamber region at a distance from the outlet valve. The invention is characterized in that a piston end face facing the channel has a region which can be immersed into the channel.

An electric submersible pumping system for use in pumping fluids from a wellbore includes a motor, a pump driven by the motor, and a fluid expansion module connected to the motor. The fluid expansion module includes a piston seal housing and a piston assembly contained within the piston seal housing. The piston assembly includes a piston body having an exterior surface, a plurality of seals connected to the exterior surface of the piston body and a pressure equalization system. The pressure equalization system reduces a pressure differential between fluid in an annular space between the plurality of seals and fluid surrounding the first piston assembly.

A hermetic compressor includes a closed vessel for storing lubricating oil, an electric-driving element, and a compressing element driven by the electric-driving element. The compressing element includes a cylinder block forming a compression chamber, a piton that reciprocates inside the compression chamber, and an oiling device for supplying the lubricating oil to an outer circumference of the piston. A first oil groove is concavely formed on the outer circumference of the piston, and a second oil groove is concavely formed on a side opposite to the compression chamber relative to the first oil groove. The second oil groove has a spatial volume same or greater than that of the first oil groove. An expanded clearance portion is provided such that a clearance between the piston and the cylindrical hole portion broadens from a top dead point to a bottom dead point.

A reciprocating piston lubrication pump with a component is proposed having an opening, which has at least one cylinder-shaped part, and with at least one piston, which comprises a radially outer surface built at least partly by a coating. A clearance between the radially outer surface of the piston and the component is between 1 μm and 20 μm when the radially outer surface is positioned in the cylinder-shaped part. The surface hardness of the coating at the radially outer surface is 2 to 10 times higher than that of a region of the component, which forms the cylinder-shaped part.

A linear compressor includes: a frame comprising a body portion, a flange portion extending from a front side of the body portion along a radial direction of the body portion, and a bearing communication hole that is in fluid communication with a front surface of the flange portion and an inner circumferential surface of the body portion, a cylinder coupled to the body portion, a piston that is disposed in the cylinder and that is configured to reciprocate along an axial direction of the cylinder, and a valve member that is disposed at the frame and that is configured to open and close the bearing communication hole based on a pressure of air between the cylinder and the piston.