Patent ID: 6809434
Filing Date: 2004-10-26
Classification: F04B,H02K,H02P

Abstract:
A vapour compressor comprising:a piston, a cylinder, said piston being reciprocable within said cylinder, the vibrating system of piston, spring and the pressure of said vapour having a natural frequency which varies with vapour pressure, a linear brushless DC motor drivably coupled to said piston having at least one winding, a DC power supply, commutation means for electronically commutating said at least one winding from said DC supply to provide a supply of current to said at least one winding to reciprocate said piston, resonant driving means which initiate commutation of said at least one winding to thereby drive said piston at the resonant frequency of said vibrating system, current controlling means which determine the amount of said supply of current supplied by said commutation means, said determined amount of current being related to said resonant frequency, and which initiate commutation of said at least one winding to thereby limit the amplitude of reciprocation of said piston.