Rotary piston compressor with no negative torque

A rotary piston compressor of trochoidal type construction with a 1:2 step-up transmission gearing operative in slip contact, comprising:

• a housing forming a compressor space, a side inlet port means in the housing, said inlet port means having a control edge located in the leading direction of rotation, an eccentrically rotating lobed piston in the compressor space forming chamber therein and having a piston edge moving ahead of and coinciding with the said control edge shortly before said piston is located in its dead-center position, a peripheral outlet port in the housing means having a rear control edge and dead-center space in communication therewith, and a follower piston lobe which at the same time, shortly before said piston is located in its dead center position, traverses the peripheral outlet port means to uncover it, to allow communication with the dead-center space for permitting relief of gas pressure in one of the chambers formed with said piston to avoid creation of any negative torque otherwise encountered therewith, the control edge of the inlet port means which trails in the direction of rotation coinciding with a trailing piston edge portion when said follower piston lobe is behind the outlet port means in the direction of rotation.