A denting device for forming a predetermined pattern on a surface near a discharge hole and an intake hole of a valve plate for a compressor includes: a seating jig to which the valve plate is fixed; a processing pin in which a pressing part for pressing the valve plate is formed at a distal end thereof; and a moving unit which is disposed on an upper portion of the seating jig, horizontally moves the processing pin at a constant speed while allowing the processing pin to vertically reciprocate at a constant speed, so as to form the pattern on the valve plate.

The present invention relates to a positive displacement pump having a delivery chamber, which is connected to a discharge connection and a suction connection, characterized in that the surface of the delivery chamber is configured in the form of an at least partially microstructured surface. The at least partially microstructured surface has a multiplicity of ribs and channels located therebetween, these running in a direction along the direction of flow of the delivery medium. As a result of the surface being structured, the situation where gas bubbles stick is reliably prevented and the harmful gas volume is considerably reduced.

The invention relates to a motor vehicle vacuum pump having a pump housing surface, on which a noise absorption cap is mounted, said cap defining a noise damping volume.

A cellular structure may include a plurality of cells. Each cell of the plurality of cells may have a twelve-cornered cross section. The twelve-cornered cross-section may include eight sides each having a first cross-sectional length, and four sides each having a second cross-sectional length that differs from the first cross-sectional length.

The invention relates to a motor vehicle vacuum pump having a pump housing surface, on which a noise absorption cap is mounted, said cap defining a noise damping volume.

A compressor comprises a housing having a hollow interior for communicating a fluid comprising a mixture of a gas and a lubricant therethrough. The hollow interior of the housing is divided into a low pressure side and a high pressure side. The low pressure side is disposed upstream of compression mechanism and the high pressure side is disposed downstream of the compression mechanism. A porous flow controller fluidly couples the high pressure side to the low pressure side. The porous flow controller is configured to meter a flow of the lubricant from the high pressure side to the low pressure side.