Piston and cylinder arrangement including means to vary the compression ratio

摘要

A piston which is reciprocable within a cylinder is rigidly connected to a bearing housing by a connection. The connection comprises a rigid tube fixed to the piston and a rigid rod fixed to the housing which extends within the tube coaxially thereof. The tube has an internal thread which engages with an external thread on the rod such that rotation of the tube changes the length of the connection and hence the position of the piston within its cylinder. The tube is rotated by way of a worm spindle which engages with longitudinal grooves formed on the external surface of the tube. The arrangement can be used particularly to vary the compression ratio of an internal combustion engine having a counter rotating crank drive.