METHOD AND APARATUS FOR STARTING A DISPLACER ENGINE HIDRAULICALLY

摘要

A method of starting a free piston combustion engine is described in which the free piston unit consisting of the combustion pistons and the piston rod connecting them is set in motion by alternately pressurizing the hydraulic cylinder spaces of a double-acting piston and cylinder arrangement whose piston or piston is or are connected to the piston rod. For this purpose pressure from a hydraulic accumulator used for starting the engine is supplied as a control pressure to the check valve members of the one way outlet check valves of the hydraulic cylinder spaces to keep those check valves closed during starting of the engine. This control pressure supplements the spring pressure supplied by springs in the check valves biasing the check valve members towards their closed positions. Simultaneously a directional valve is used to channel hydraulic fluid from the hydraulic accumulator directly to the cylinder spaces in turn, thereby bypassing the one way inlet check valves to the cylinder spaces. In this way the free piston unit is set in motion. Once the free piston has performed a predetermined number of reciprocating movements or has attained a sufficient magnitude of inertial energy the hydraulic accumulator is disconnected so that the inlet and outlet valves can perform their normal function, while simultaneously or just before or just after this moment fuel combustion is initiated to maintain the engine in operation. An electronic controller responsive to signals from sensors mounted on the engine from which can be derived information about the position and speed of the free piston unit can be used to control starting and operation of the engine.