A pressure monitoring apparatus for a membrane compressor, with at least one pressure transducer for recording the pressure within a certain volume, with at least one nonreturn valve and with at least one shutoff valve, for blocking of the nonreturn valve, the shutoff valve and the nonreturn valve each being located in a flow path through which a medium can flow between the volume and the pressure transducer. A pressure monitoring unit delivers exact measured values and which can be economically implemented is achieved by there being at least two nonreturn valves which are located anti-parallel in respective flow paths, the first nonreturn valve blocking in the flow direction from the volume to the pressure transducer and the second nonreturn valve blocking in the flow direction from the pressure transducer to the volume, and by there being at least two shutoff valves for blocking a respective flow path.

The piston ring assembly having a first and a second endless sealing ring and an elastic ring carrier, the first and the second sealing ring extending in a circumferential direction (U) and each having an outer circumferential surface, the first sealing ring having a first center point (M1) with respect to its outer circumferential surface and the second sealing ring having a second center point (M2 ) with respect to its outer circumferential surface, the first and second sealing rings each having a longitudinal axis (L) running perpendicular to the circumferential direction (U), wherein the ring carrier runs in the circumferential direction (U), and wherein the ring carrier and the first and second sealing rings are designed to be mutually adapted in such a way that the first and second sealing rings are arranged one after the other in the ring carrier in the direction of the longitudinal axis (L), and in that their first and second centers (M1, M2) are arranged at a distance from one another radially with respect to the longitudinal axis (L), the sealing rings being pressed in opposite directions against the inner wall of a cylinder when the piston ring assembly is used in accordance with the invention.

A rotor has at its two axis end portions an upper large-diameter inner circumferential portion and a lower large-diameter inner circumferential portion that have inner diameters larger than the inner diameter of the axially middle portion of the rotor and are offset in the radial direction. A crankshaft has a passageway, which is formed in the crankshaft and allows refrigerant to flow therethrough, and a gas venting hole, which provides communication between the passageway and at least one discharge opening formed in the outer circumferential surface of the crankshaft. The at least one discharge opening is formed at a position facing the inner circumferential surface of the lower large-diameter inner circumferential portion 5b on the compression unit side.

A rotor has at its two axis end portions an upper large-diameter inner circumferential portion and a lower large-diameter inner circumferential portion that have inner diameters larger than the inner diameter of the axially middle portion of the rotor and are offset in the radial direction. A crankshaft has a passageway, which is formed in the crankshaft and allows refrigerant to flow therethrough, and a gas venting hole, which provides communication between the passageway and at least one discharge opening formed in the outer circumferential surface of the crankshaft. The at least one discharge opening is formed at a position facing the inner circumferential surface of the lower large-diameter inner circumferential portion 5b on the compression unit side.

A preheater for a compressor that is capable of heating a lubricant oil efficiently with smaller power is provided. A preheater for a compressor includes: a capacitive oil surface sensor that is provided at a compressor used in a refrigerating cycle, and detects an oil surface of a lubricant oil A in the compressor; and a power supply unit that applies high-frequency voltage to the oil surface sensor.

The present invention relates to a fluidic cylinder. This fluidic cylinder is configured in such a manner that a piston unit is received in an axially displaceable manner within a cylinder tube formed in a rectangular cross-sectional shape. The piston unit has: a base body having the front end of a piston rod staked thereto; a wear ring having the base body received therein and having a magnet incorporated therein; and piston packing adjacent to the wear ring. The piston unit is integrally held at one end of the piston rod. The wear ring and the piston packing are formed in a rectangular cross-sectional shape corresponding to the rectangular cross-sectional shape of the cylinder tube and are provided rotatable relative to the piston rod.

An air compressor assembly may include a support structure, an operating unit including a compressor operatively connected to a motor through at least one drive belt, and at least one vibration isolator that is positioned between at least a portion of the support structure and at least a portion of the operating unit. The vibration isolator(s) is configured to dampen vibratory energy generated by the operating unit.

The present invention provides a shaft-cylinder assembly for high-temperature operation comprising a pair of first and second dynamic sealing members having a helical coiled seal ring structure configured to be in contact with the shaft for providing dynamic sealing function in the cylinder; and a cylindrical cooling jacket configured to circumferentially surround the dynamic sealing members such that a cavity is defined between the dynamic sealing members inside the cooling jacket; wherein the cooling jacket comprises one or more inflow cooling channels and one or more outflow cooling channels configured to communicating with the cavity and circulating a cooling fluid through the cavity for moving heat away from the dynamic sealing members.

An oil separator includes a heating device that heats liquid stored in a liquid storage portion, a connecting pipe that connects the liquid storage portion to an external device that utilizes oil, an opening/closing device that selectively opens and closes the flow path of the connecting pipe, and a determination device that determines whether the liquid stored in the liquid storage portion should be delivered to the external device. The opening/closing device is configured to open the flow path of the connecting pipe when the determination device determines that the liquid accumulated in the liquid storage portion should be delivered to the external device.

In order to prevent working medium from accumulating in the compressor housing (2) of a piston compressor (1) in a simple manner by means of a sealing of the piston rod (7) in the form of sealing medium barrier supplied by a hydraulic unit (12), it is provided that a ventilator (32) and a sealing medium container (37), which is partially filled with sealing medium, are provided in the hydraulic unit (12), wherein the ventilator (32) suctions air from the free space of the sealing medium container (37), and the free space (45) in the sealing medium container (37) is connected via a line (15, 17) to the compressor housing (2), and an opening (16) is provided at the compressor housing (2) for connecting the interior of the compressor housing (2) to a purge gas reservoir (18).