Rod journal movable variable compression ratio mechanism

The invention provides a rod journal movable variable compression ratio mechanism. The mechanism comprises an eccentric device, a control motor, a bull gear, a pinion, a crankshaft body and a connecting rod; the eccentric device is embedded into a large end of the connecting rod; the bull gear is fixedly connected with the eccentric device and is concentric with a journal of the crankshaft body; the bull gear is meshed with the pinion; a shaft of the pinion is an output shaft of the control motor; the control motor is fixedly connected with the crankshaft body; and when the eccentric device rotates, the center of the large end of the connecting rod is pushed to be close to or away from the rod journal and further the compression ratio is changed. Compared with the scheme of changing the compression ratio of an existing multi-linkage mechanism, the rod journal movable variable compression ratio mechanism has the advantages that firstly, the occupied space is small, the swing of the connecting rod is symmetrica