RevisionC-Developmentofconceptofcompressorforcommercialvehicle

horizontal double-acting cylinders are also arranged on each side, all operated from a single
crankpin.
There are many applications of industrial compressors in which the oil in the gas stream
cannot be tolerated. The oil-free compressed air is essential in industries such as the food
industry, the brewing industry and the packaging (Pharmaceuticals) industry as well as in some
industrial air control systems.
But even in general industry or manufacturing, there may be reasons to consider reducing
the amount of lubricating oil used in the compressor cylinders. The excess oil can build up in the
discharge valve port 10 areas, and even the best premium grades of compressor oil will oxidize
when subjected to high temperatures. These oils may eventually form gummy or sludge-like
deposits, which reduce the performance of a compressor and in some cases lead to fires in the
air system if they are allowed to build up. For these and other reasons, non-lubricated operation
has become increasingly popular.
The oil free piston compressors subjected to a greater number of premature bearing
failures in the transmission system. In this design, it is not possible to have sliding bearings due
to the absence of oil for lubrication. Unlike in oil flooded machines, cylindrical roller bearings are
not possible to implement due to the space constraint and difficulty in self lubrication.
Meece et al., (1974) described the designing of oil-less reciprocating, rotary vane,
diaphragm compressors and pumps. Since the widespread use of oil-less air is relatively new;
particular emphasis will be stressed on the design features and considerations, which distinguish
the oil less unit from a lubricated unit. The media being pumped is not exposed to an oil lubricant.
The piston pin needle bearings are contained in the connecting rod and are sized to a slip fit over
the piston pin. Since the needle bearings have very limited grease storage capacity, the
connecting rods are usually designed with an integral grease reservoir between the bearings.
Other than these compressors there is dynamic impulse type compressor, that is nonpositive
displacement compressor. And are not used for commercial vehicle purpose.
They can be one of below: -
i) Centrifugal
ii) Centrifugal mixed-flow
iii) Centrifugal axial flow
The centrifugal air compressor is a dynamic compressor which depends on transfer of
energy from a rotating impeller to the air. Centrifugal compressors produce high-pressure
discharge by converting angular momentum imparted by the rotating impeller (dynamic
displacement). In order to do this efficiently, centrifugal compressors rotate at higher speeds than
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