In an amorphous carbon film of a sliding member, provided that a number of nitrogen atoms each singly bonded to three carbon atoms is A, and a number of nitrogen atoms each singly and doubly bonded to two carbon atoms, respectively, is B, a value A/B of the amorphous carbon film obtained through X-ray photoelectron spectroscopy analysis is 10 to 18. The method includes irradiating the surface of the substrate with nitrogen ion beams and irradiating a carbon target with electron beams, thereby forming an amorphous carbon film on the surface of the substrate while vapor-depositing a part of the carbon target onto the surface of the substrate. The output of the electron beams that irradiate the carbon target is 30 to 50 W.

A rotary compressor includes: a compressing unit that includes an annular cylinder, an end plate, an annular piston which is fit in an eccentric portion of a rotation shaft, and a vane which protrudes from the inside of a vane groove of the cylinder to the inside of an operation chamber, comes into contact with the annular piston, and partitions the operation chamber into an inlet chamber and a compression chamber. The vane is formed of steel and has a diamond-like carbon layer formed on a sliding surface with respect to the annular piston. The annular piston is formed of NiCrMo cast iron to which 0.15 wt % to 0.45 wt % of phosphorus is added, or is formed of cast iron or steel and has an iron nitride layer formed on an outer circumferential surface thereof.

A gaseous fluid pump includes a compression chamber, a plurality of pistons, a plurality of electric coils, and a magnet. The chamber contains at least one inlet and one outlet and a plurality of open volumes created by an inner surface of the compression chamber. The plurality of pistons are within the compression chamber and each piston containing a body with at least a first diametrically polarized magnet centered in the body such that the first magnet attracts or repels depending on the relative position of the first magnet. The plurality of electric coils wound around laminations on an outside of the compression chamber with each of the plurality of electric coils configured to create flux paths centered around each of the pistons when provided electricity to act as a polarizing motor stator. A second magnet is centered within the compression chamber between two of the plurality of pistons.

An external rotor pump, in particular a hydraulic external rotor pump, has a first component which is configured as an outer rotor with a sliding surface which is arranged on the outer side thereof, and a second component which is configured as an opposing body and in which the outer rotor is mounted rotatably by way of the sliding surface thereof on an inner guide surface of the opposing body and is in mechanical contact with the inner guide surface. An inner rotor which is mounted such that it can be rotated eccentrically with respect to the outer rotor is provided. One of the rotors can be driven, in order to be set into a rotational movement, and the rotors are coupled to one another such that, when the drivable rotor is driven, the other rotor is likewise set into a rotational movement as a result, in order to convey fluid from a suction region to a pressure region of the external rotor pump. The sliding surface or the guide surface has a surface structure which has a load-bearing region and a non-load-bearing region which is depressed in contrast with the former. The result is that the non-load-bearing region is saved from contact between the guide surface and the sliding surface which is mounted thereon.

The invention relates to a reciprocating piston composed of ceramic material for a reciprocating-piston engine with crank drive, wherein the reciprocating piston is rigidly screwed to a piston rod by a screw, wherein between the reciprocating piston and the piston rod there is braced at least one disc composed of metallic material, wherein the screw is composed of a metallic material, wherein the coefficient of thermal expansion .sub.piston of the material of the reciprocating piston is lower than the coefficient of thermal expansion .sub.screw of the material of the screw, and the disc is an expansion compensation disc, wherein the coefficient of thermal expansion .sub.Disc 1;2 of the material of the expansion compensation disc is greater than the coefficient of thermal expansion .sub.screw of the material of the screw, and to a reciprocating-piston engine having a reciprocating piston of said type, and to a cylinder of a reciprocating-piston engine having a cylinder of said type.

A method of controlling a fluid pump. The pump has a plurality of oscillating pistons that travel along a central axis of a piston sleeve. A plurality of pistons is of similar mass within a piston sleeve are provided, and adjacent pistons are positioned to be 180 degrees apart in phase oscillations. An electric coil is provided for each piston, and the position of adjacent pistons is determined. The current to one of the electric coils for a piston is adjusted to maintain the 180 degree difference in phase between oscillations of adjacent pistons.