Research on a prototype spark ignition (SI) variable compression ratio engine fitted with a pneumatic energy accumulator

The paper describes investigations performed on a prototype variable compression ratio engine fitted with a pneumatic energy accumulator. The engine was built in the Chair of Vehicles and Basics of Machine Design at Lodz University of Technology. Due to the design and principle of operation, the engine may be an alternative to the already existing VCR engines. The pneumatic energy accumulator fitted in the cylinder head with an additional moving piston allows continuous adjustment of the compression ratio. The system is adaptive and adjusts itself to the engine load, reducing the increment of maximum pressure inside the cylinder. The research focuses on the influence of adjustment parameters of the energy accumulator on the movement of the additional piston and engine performance. Engine operation stability and reproducibility of the cycles has also been investigated. An attempt was made to characterize the engine and the energy accumulator in terms of efficiency and range of applicability (profitability of application).