Ford Global Technolgoies, LLC

Lixin Peng

Peter Hofbauer

Jialin Yang

Cliff Carlson

Adrain Tusinean

Kevin Berent Fuqua

Jing Ping Liu

Wang Yanmin

Ing Peter Hofbauer

A free piston engine is configured with a pair of opposed engine cylinders located on opposite sides of a fluid pumping assembly. An inner piston assembly includes a pair of inner pistons, one each operatively located in a respective one of the engine cylinders, with a push rod connected between the inner pistons. The push rod extends through an inner pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. An outer piston assembly includes a pair of outer pistons, one each operatively located in a respective one of the engine cylinders, with at least one pull rod connected between the outer pistons. The pull rod extends through an outer pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. Piston stoppers are provided to prevent over-travel of the piston assemblies.

Piston stopper for a free piston engine

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. The actuator force is a periodic force preferably having a frequency that is the same or nearly the same as the natural frequency of the system that includes the inertia of the pistons and other masses reciprocating with the pistons and the variable spring, represented by the compressible air spring in the combustion chamber. When piston displacement reaches a sufficient magnitude, fuel is admitted to the air charge, preferably by injection. The actuator continues to increase piston displacement and the compression pressure of the air-fuel mixture in the cylinder until combustion of that mixture in the first cylinder occurs. Fuel is then admitted to the second cylinder while continuing cyclic displacement of the pistons, and combustion of the fuel-air mixture in the second cylinder occurs.

Compression pulse starting of a free piston internal combustion engine

A free piston engine is configured with a pair of opposed engine cylinders located on opposite sides of a fluid pumping assembly. An inner piston assembly includes a pair of inner pistons, one each operatively located in a respective one of the engine cylinders, with a push rod connected between the inner pistons. The push rod extends through an inner pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. An outer piston assembly includes a pair of outer pistons, one each operatively located in a respective one of the engine cylinders, with at least one pull rod connected between the outer pistons. The pull rod extends through an outer pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. The movement of the inner and outer piston assemblies during engine operation will cause the fluid plungers to pump fluid from a low pressure container into a high pressure chamber as a means of storing the energy output from the engine. Alternatively, the piston assemblies may drive a linear alternator. Each fuel injector is located so that it injects directly into its cylinder near the intake ports, while also being covered during combustion events in order to avoid exposing the fuel injector to the harsh environment of combustion.

Fuel injection for a free piston engine

A free piston engine is configured with a pair of opposed engine cylinders located on opposite sides of a fluid pumping assembly. An inner piston assembly includes a pair of inner pistons, one each operatively located in a respective one of the engine cylinders, with a push rod connected between the inner pistons. The push rod extends through an inner pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. An outer piston assembly includes a pair of pistons, one each operatively located in a respective one of the engine cylinders, with at least one pull rod connected between the outer pistons. The pull rod extends through an outer pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. Each outer piston cooperates with an integrated scavenge pump in order to compress the charge air, thus significantly increasing the air charge density into the engine cylinders for each stroke of the engine.

Air charging system for an opposed piston opposed cylinder free piston engine

A free piston engine is configured with a pair of opposed engine cylinders located on opposite sides of a fluid pumping assembly. An inner piston assembly includes a pair of inner pistons, one each operatively located in a respective one of the engine cylinders, with a push rod connected between the inner pistons. An outer piston assembly includes a pair of pistons, one each operatively located, in a respective one of the engine cylinders, with at least one pull rod connected between the outer pistons. The pull rod extends through an outer pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. Each outer piston cooperates with an integrated scavenge pump in order to compress the charge air, thus significantly increasing the air charge density into the engine cylinders for each stroke of the engine.

Air scavenging for an opposed piston opposed cylinder free piston engine

A free piston engine is configured with a pair of opposed engine cylinders located on opposite sides of a fluid pumping assembly. An inner piston assembly includes a pair of inner pistons, one each operatively located in a respective one of the engine cylinders, with a push rod connected between the inner pistons. The push rod extends through an inner pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. An outer piston assembly includes a pair of outer pistons, one each operatively located in a respective one of the engine cylinders, with at least one pull rod connected between the outer pistons. The pull rod extends through an outer pumping chamber in the fluid pumping assembly and forms a fluid plunger within this chamber. The movement of the inner and outer piston assemblies during engine operation will cause the fluid plungers to pump fluid from a low pressure container into a high pressure chamber as a means of storing the energy output from the engine. Alternatively, the piston assemblies may drive a linear alternator. The exhaust ports for each engine cylinder are sized and located to retain the desired amount of internal EGR in each cylinder without the need for exhaust valves. As an alternative, an external EGR system may supplement the internal EGR in order to obtain the desired EGR at the desired temperature.

Exhaust gas recirculation for a free piston engine

An inlet air compressor for an internal combustion engine is provided which has one inlet and a plurality of outlets. Within the compressor are disposed a plurality of diffusers coupled to the plurality of outlets. The flow is divided among the plurality of outlets so that at conditions of low overall flow rate through the engine, which would, in a compressor according to the prior art, ordinarily surge, allow the flow to be substantially discontinued through one or more diffusers and continue at through the remaining diffusers. In this way, the diffusers with flow operate within an acceptable operating range and avoid a surging condition. The present invention is directed to engines having a wide range of flow rates. A couple of examples are gasoline engines and variable displacement engines.

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Rochester Hills, MI, United States of America

Lixin Peng