US Patent 7117779 Driver for power tools

A power source (10) for providing energy to drive a mechanical device including a receiving chamber (11) and discrete propellant charges (23) for selective detonation whereby gases generated by the selective detonation expand into the receiving chamber (11) wherein said receiving chamber includes a reactive closure (15) which dynamically responds to pressure changes in the receiving chamber and wherein said power source further includes a linkage (16) associated with the reactive closure for transmitting energy from the dynamic response of the reactive closure to the mechanical device.