Abstract: A free piston engine system, particularly suitable for use in a motorized vehicle, is provided with at least one hydraulic pump, each pump having a first fluid port and a second fluid port. A free piston internal combustion engine includes a combustion cylinder and a hydraulic cylinder. A low pressure accumulator is fluidly coupled with the hydraulic cylinder. A first control valve interconnects the low pressure accumulator with the hydraulic cylinder. At least one high pressure accumulator is fluidly coupled with the hydraulic cylinder. At least one second control valve is provided, with each second control valve interconnecting a respective high pressure accumulator with the hydraulic cylinder. A third control valve interconnects the hydraulic cylinder with the first fluid port of each pump. A fourth control valve interconnects the hydraulic cylinder with the second fluid port of each pump. A first working pressure accumulator is coupled between each pump and the third control valve or fourth control valve.

Abstract: A twin-turbocharged internal combustion engine improves compression efficiency and improves response by serial arrangement of a first turbocharger and a second turbocharger. An exhaust gas recirculation (EGR) system using boost cooling reduces emissions of nitrogen oxides (NOx). The EGR system cools recirculated exhaust gas by exchanging heat with compressed, cooled combustion air in an EGR heat exchanger. The second turbocharger has a variable geometry turbine to control flow of recirculated exhaust gas.

Abstract: A free piston internal combustion engine includes a housing with a combustion cylinder and a hydraulic cylinder. A piston includes a piston head reciprocally disposed within the combustion cylinder and movable during a compression stroke to a top dead center position and during a return stroke to a BDC position. A plunger head is reciprocally disposed within the hydraulic cylinder. A plunger rod interconnects and is rigidly affixed to each of the piston head and the plunger head. The plunger head and the hydraulic cylinder define a variable volume pressure chamber on a side of the plunger head generally opposite the plunger rod.

Abstract: An improved method and system for controlling exhaust gas recirculation on an internal combustion engine broadens the operating range. The system includes a plurality of combustion chambers, a recirculation combustion chamber, fuel delivery device, engine condition sensing device, and controller. The system measures engine condition to determine a total fuel mass to meet engine condition. The system then uses the recirculation manifold to set volume of recirculated air and adjusts fuel delivery to the recirculation manifold to set quality of the recirculated gas. The remainder of fuel is divided generally equally among the plurality of combustion chambers.

Abstract: A free piston internal combustion engine includes a housing with a combustion cylinder and a hydraulic cylinder. A piston includes a piston head reciprocally disposed within the combustion cylinder and movable during a compression stroke to a top dead center position and during a return stroke to a BDC position. A plunger head is reciprocally disposed within the hydraulic cylinder. A plunger rod interconnects and is rigidly affixed to each of the piston head and the plunger head. The plunger head and the hydraulic cylinder define a variable volume pressure chamber on a side of the plunger head generally opposite the plunger rod.

Abstract: An exhaust gas recirculation (EGR) system for a turbo-charged internal combustion engine is provided. The EGR system includes a recirculation conduit for recirculating a volume of exhaust gas from the exhaust manifold to the intake manifold; a cooling air conduit for transporting a flow of cooling air; and a gas-to-air heat exchanger disposed in operative association with the recirculation conduit and the cooling air conduit and adapted for cooling the volume of recirculated exhaust gas in the recirculation conduit. The cooling air passing through the gas-to air heat exchanger can be diverted from the pressurized intake air, cooled (ATAAC) air, or even fresh ambient air obtained from a source external to said engine and which optionally may be forcibly directed through the heat exchanger via a blower.

Abstract: A free piston internal combustion engine includes a combustion cylinder having an inside surface. A piston is reciprocally disposed within the combustion cylinder. The piston includes a piston head and a plunger rod attached to the piston head. The piston head has an outside surface lying closely adjacent to and defining a bearing surface with the inside surface of the combustion cylinder. The bearing surface consists essentially of a non-metallic material.

Abstract: A free piston internal combustion engine includes a housing with a combustion cylinder and a second cylinder. A piston includes a piston head reciprocally disposed within the combustion cylinder, a second head reciprocally disposed within the second cylinder, and a plunger rod rigidly attached to each of and interconnecting the piston head and the second head. The piston head defines a bearing with the inside surface of the combustion cylinder. A single bearing is carried by the housing within the second cylinder and reciprocally carries the plunger rod. The single bearing is the only bearing which directly carries the plunger rod.

Abstract: A method of operating a free piston engine of the present invention, includes a housing with a combustion cylinder and a second cylinder. A piston includes a piston head reciprocally disposed within the combustion cylinder, a second head reciprocally disposed within the second cylinder, and a plunger rod interconnecting the piston head with the second head. A supply of hydraulic fluid is pulsed from a high pressure hydraulic accumulator into a pressure chamber in the second cylinder adjacent the second head during a beginning portion of a compression stroke to cause the piston head to move toward a top dead center position. The high pressure hydraulic accumulator is decoupled from the pressure chamber after the pulsing step. A low pressure hydraulic accumulator is coupled with the pressure chamber during a remaining portion of the compression stroke. The high pressure hydraulic accumulator is coupled with the pressure chamber when the piston head is traveling toward a BDC position during a return stroke.

Abstract: A free piston internal combustion engine includes a combustion cylinder having an inside surface. A piston which is reciprocally disposed within the combustion cylinder includes a piston head and a plunger rod. The plunger rod is attached to the piston head and has a longitudinal axis. The piston head includes a non-metallic cap and a metallic skirt. The cap has a outside surface lying closely adjacent to and defining a bearing surface with the inside surface of the combustion cylinder. The cap is substantially immovably attached to the skirt in a direction parallel to the longitudinal axis of the plunger rod, and is movably attached to the skirt in a radial direction relative to the longitudinal axis of the plunger rod.

Abstract: A method of operating a free piston engine of the present invention provides a piston including a piston head reciprocally disposed within a combustion cylinder, a plunger head reciprocally disposed within a hydraulic cylinder, and a plunger rod interconnecting the piston head with the plunger head. The plunger head and the hydraulic cylinder define a variable volume pressure chamber on a side of the plunger head generally opposite the plunger rod. A supply of hydraulic fluid is pulsed from a high pressure hydraulic accumulator into the pressure chamber during a beginning portion of a compression stroke to cause the piston head to move toward a top dead center position. The high pressure hydraulic accumulator is then decoupled from the pressure chamber.

Abstract: A method of operating a free piston engine with a housing including a combustion cylinder and a second cylinder. A piston includes a piston head reciprocally disposed within the combustion cylinder, a second head reciprocally disposed within the second cylinder, and a plunger rod interconnecting the piston head with the second head. The second head and the second cylinder define a variable volume pressure chamber on a side of the second head generally opposite the interconnecting plunger rod. The piston is moved between a bottom dead center position and a top dead center position during a compression stroke. A fuel and air mixture is combusted in the combustion cylinder when the piston is at or near the top dead center position. The piston is moved between the top dead center position and the bottom dead center position during a return stroke. A hydraulic accumulator is coupled with the pressure chamber during the return stroke.

Abstract: The present invention improves the operation of an exhaust gas recirculation system having a recirculation combustion chamber or group of combustion chambers dedicated to supplying recirculated gas. Once a sensed engine load is within a predefined range, a controller advances fuel injection into the recirculation combustion chamber to reduce formation of particulates. The reduction in particulates reduces fouling of an exhaust gas recirculation system.

Abstract: A system and method for recirculating exhaust gas in a turbocharged internal combustion engine is disclosed. The disclosed method comprises the steps of: (a) recirculating a selected volume of exhaust gas from the exhaust manifold to the intake manifold via a recirculation conduit; (b) diverting a flow of cool intake air to bypass the engine via a bypass conduit; and (c) cooling the recirculating exhaust gas in the recirculation conduit using the flow of diverted intake air.

Abstract: An exhaust gas recirculation (EGR) system for a pressure-charged internal engine for use in a high load condition is presented. The disclosed EGR system includes one or more exhaust combustion chambers attached to a recirculation manifold. A pressure sensor is located in an inlet air manifold. Where the pressure in the inlet manifold is above a predetermined level, a flow control device directs recirculation flow through a supply conduit into the inlet manifold. The disclosed embodiment includes an EGR cooling system where cool air in a bleed conduit connecting an inlet conduit to the exhaust manifold exchanges heat with exhaust gas in the supply. A bleed valve in the bleed conduit moves in response to temperature in the supply duct along with the position of the flow control device to prevent condensation in the combustion chambers. The invention also includes methods for controlling EGR system and EGR cooling system.

Abstract: An exhaust gas recirculation (EGR) system for a turbo-charged internal combustion engine is provided. The EGR system includes a recirculation conduit for recirculating a volume of exhaust gas from the exhaust manifold to the intake manifold; a bypass conduit for diverting a flow of intake air around the engine; and an EGR cooler disposed in operative association with the recirculation conduit and the bypass conduit and adapted for cooling the volume of recirculated exhaust gas in the recirculation conduit. The exhaust gas recirculation cooler or heat exchanger is also adapted for concurrently heating the intake air in the bypass conduit. The heated intake air together with the exhaust gas remaining in the exhaust manifold is used to drive the turbocharger. The disclosed embodiment of the exhaust gas recirculation system also includes an air-to-air after-cooler used to cool the compressed intake air.

Abstract: A constant rate exhaust gas recirculation (EGR) system for a pressure-charged internal combustion engine is provided. The disclosed exhaust gas recirculation system includes one or more exhaust gas diversion ports, one or more EGR diversion valves each of which is operatively associated with a selected combustion chamber for diverting a flow of exhaust gas from the selected combustion chambers via an exhaust gas recirculation conduit to the intake air circuit of the pressure-charged internal combustion engine. The disclosed embodiment of the constant rate EGR system also includes a bypass conduit for diverting a flow of intake air to the exhaust manifold and an EGR cooler disposed in operative association with the recirculation conduit and the bypass conduit and adapted for cooling the volume of recirculated exhaust gas in the recirculation conduit while concurrently heating the intake air in the bypass conduit.