A hydraulic device includes a shaft mounted in a housing rotatable about a first axis of rotation. The shaft has a flange extending perpendicularly to the first axis. A plurality of pistons is fixed to the flange. A plurality of cylindrical sleeves cooperates with the pistons to form respective compression chambers of variable volume. The cylindrical sleeves are rotatable about a second axis of rotation which intersects the first axis of rotation by an acute angle such that upon rotating the shaft the volumes of the compression chambers change. Each piston has a piston head including a circumferential wall of which the outer side is ball-shaped and the inner side surrounds a cavity. Each of the pistons is fixed to the flange by a piston pin having a piston pin head including a circumferential outer side facing the inner side of the circumferential wall of the piston head.

A piston pump as a high-pressure fuel pump of a common rail system includes: a pump cylinder; a pump piston moveably mounted in a recess of the pump cylinder, the pump piston being moveable up and down in the recess; and a leakage groove arranged in the pump cylinder in a region of the recess, the leakage groove being coupled with a leakage line configured to discharge a fuel leakage. Between the pump cylinder and the pump piston a different size pairing clearance is formed in first and second portions of the pump cylinder.

A linear compressor is provided. The linear compressor may include a cylinder that defines a compression space for a refrigerant; a piston that axially reciprocates inside the cylinder; a motor configured to provide a drive force to the piston; a discharge valve configured to discharge the refrigerant compressed in the compression space; and a discharge cover having a discharge space in which the refrigerant discharged through the discharge valve flows. The discharge valve and the discharge cover may be arranged inside the motor.

A linear compressor includes a cylinder that defines a compression chamber configured to accommodate refrigerant and that includes a cylinder nozzle configured to receive refrigerant, and a piston provided in the cylinder and configured to be pressed by refrigerant in the cylinder. The piston includes a piston body configured to move forward and backward within the cylinder, a piston front part located on a front surface of the piston body, the piston front part comprising a suction port through which refrigerant is supplied into the compression chamber, and a refrigerant collection part that is recessed from an outer circumferential surface of the piston front part, that extends to a front surface of the piston front part, and that is configured to receive at least a portion of refrigerant compressed in the compression chamber.

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 linear compressor is provided. The linear compressor may include a cylinder that defines a compression space for a refrigerant; a piston that axially reciprocates inside the cylinder; a motor configured to provide a drive force to the piston; a discharge valve configured to discharge the refrigerant compressed in the compression space; and a discharge cover having a discharge space in which the refrigerant discharged through the discharge valve flows. The discharge valve and the discharge cover may be arranged inside the motor.

A reciprocating compressor is provided. The reciprocating compressor may include a cylinder having a compression space, a piston inserted into the cylinder to define the compression space while being reciprocated, the piston having a suction passage to communicate with the compression space, a gas bearing having at least one bearing hole that passes through the cylinder, so that a refrigerant gas may be injected between the cylinder and the piston to support the piston with respect to the cylinder, and a flow resister disposed at an outer circumferential surface of the cylinder or at one side of the cylinder to restrict a flow of the refrigerant gas flowing through or toward the at least one bearing hole.

A method for operating a linear compressor includes establishing a set of predictors, and establishing a model for an estimated head clearance of the linear compressor with the set of predictors. Coefficients of the model for the estimated head clearance of the linear compressor may also be established. The model for the estimated head clearance of the linear compressor may be used to calculate an estimated head clearance during operation of the linear compressor.

A reciprocating pump includes a first manifold which includes a pump chamber, a second manifold which is connected to the first manifold, and a seal which is disposed inside the second manifold and comes into slidable contact with a plunger. A communication pipe which extends across an inside of the first manifold and an inside of the second manifold comes into contact with the seal. Additionally, the reciprocating pump includes a collar which is disposed inside the first manifold and comes into contact with the communication pipe through which the plunger is inserted. The collar, the communication pipe, and the seal are sandwiched between the inside of the first manifold and the inside of the second manifold.

The present invention relates to a piston assembly for pumping a liquid, in particular in a bottle filling system. The object of the invention is to propose a piston assembly for pumping a liquid, which can be cleaned and/or disinfected without dismantling of the piston or performing any other external interventions into the assembly. The object is achieved by a piston assembly for pumping a liquid, which comprises a piston 1 that travels within a cylinder 2 and has a working path A between a first inversion point U1 and a second inversion point U2, with the piston 1 forming a tight seal with respect to the cylinder 2 in the region of the working path. The assembly is characterized in that beyond one of the two inversion points U1, U2, outside of the working path A, the diameter of the cylinder 2 is enlarged in one section 8 such that the sealing closure is eliminated there, and the piston 1 can be moved into this area for a cleaning and/or disinfection process.