Equivalent Linkages of Compressor Mechanisms

Frequently, the dynamics of a compressor’s mechanism can be simplified and better understood by analyzing compressor’s equivalent linkage. Although the equivalent linkage of a reciprocating piston compressor is well known, the equivalent linkages of other types of compressors are not. For example, it is not well understood that the equivalent linkage of a rolling piston compressor is also the same slider-crank mechanism as the one of a reciprocating piston compressor. The difference between reciprocating piston compressor and the rolling piston compressor is that it is the connecting rod that compresses gas in the cylindrical chamber. If the contact between the rolling piston and the vane is flat, the equivalent linkage is the Scotch-Yoke mechanism. The difference between the two equivalent linkages of the same type of compressor is in the type of contact between the vane and the rolling piston. The equivalent linkage of a rotary vane compressor is the rocker arm mechanism. The equivalent linkage of a scroll compressor has two degrees of freedom and it has Oldham Ring. The equivalent linkages of other types of compressor mechanisms can be readily found by using approach presented in the paper. Under usual assumption of constant angular velocity, the dynamic analysis of the equivalent linkage can be done in vector form. Thus, the vectors of velocities and accelerations may be projected into the direction of a chosen coordinates. Therefore, one will only need to know geometry of the linkage as a function of the angle of crank rotation. This approach enables to avoid cumbersome time derivatives