Patent ID: 7942117

Claim:
An engine comprising: an air compression module comprising at least two compressors, each having a compressor inlet and a compressor outlet, wherein at least one of the compressors comprises a first piston-cylinder device having a compressor inlet valve at the inlet and compressor outlet valve at the output; first means for conducting compressed air from the compressor outlet of the first compressor to the inlet of the second compressor; and second means for conducting compressed air from the outlet of the second compressor; an expander module comprising a second piston-cylinder device having a variable volume, wherein the second piston-cylinder device comprises: a cylinder defining a head, a piston having a face, wherein the piston is reciprocal within said cylinder from a top dead center position wherein the face is near the head and the volume of the second piston-cylinder device is minimized, to a bottom dead center position wherein the face is moved away from the head and the volume of the second piston-cylinder device is maximized; a duct having a first opening at one end into said cylinder through the head and a second opening for receiving compressed air from the second compressor; an expander inlet valve near the second opening of the duct for controlling the flow of compressed air into the duct which expander inlet valve is open when the piston is at the top dead center position and closes when the piston reaches a selected point between the top dead center position and the bottom dead center position; an injector for injecting fuel into the duct wherein fuel and compressed air are mixed to form a mixture, igniting means for igniting the mixture when the piston is near the top dead center position whereby the mixture combusts and expands, driving the piston toward the bottom dead center position and forming heated exhaust gas; and wherein the second piston cylinder device further comprises an expander outlet valve near the head for controlling the expulsion of heated exhaust gas, and wherein said outlet valve is open when the piston is at the bottom dead center position and is closed at a selected point as the piston moves toward the top dead center position allowing exhaust gas remaining in the cylinder to be recompressed; and wherein the engine further comprises means for conducting the exhaust gas from the expander outlet valve.