Abstract: A method for starting an engine uses an actuator, such as a hydraulic or pneumatic pump-motor or an electric linear alternator-starter to move the pistons to a position where the inlet ports are opened. This ensures that air is present in the cylinder in a space where fuel will be admitted and combustion will occur. This strategy compresses, with a minimum actuator capacity, such air to a state that the pressure and temperature satisfy the ignition requirements. The air stores kinetic energy of the moving pistons that partially form the air spring force of the opposite cylinder and partially from the actuator. Accumulation, cycle by cycle, of this stored energy accelerates the piston motion, increases the piston displacement, and increases the compression ratio. The cylinder pressure and temperature increas cycle by cycle until the fuel ignition conditions are satisfied.

Abstract: A method for starting an engine uses an actuator, such as a hydraulic or pneumatic pump-motor or an electric linear alternator-starter to move the pistons to a position where the inlet ports are opened. This ensures that air is present in the cylinder in a space where fuel will be admitted and combustion will occur. This strategy compresses, with a minimum actuator capacity, such air to a state that the pressure and temperature satisfy the ignition requirements. The air stores kinetic energy of the moving pistons that partially form the air spring force of the opposite cylinder and partially from the actuator. Accumulation, cycle by cycle, of this stored energy accelerates the piston motion, increases the piston displacement, and increases the compression ratio. The cylinder pressure and temperature increas cycle by cycle until the fuel ignition conditions are satisfied.