A variable compression ratio control system for an internal combustion engine

A variable compression ratio control system for an internal combustion engine 10 includes an engine driven accessory hydraulic pump 12 and a hydraulic accumulator system 16 for receiving hydraulic fluid from the engine driven accessory pump 12. The hydraulic accumulator 16 also receives engine oil from an engine oil pump 20. A variable compression ratio actuator 14 is supplied with high pressure engine lubricating oil from the hydraulic accumulator system 16 so as to control the compression ratio of the engine 10.