Free-piston engine without compressor

A double-acting tandem free-piston engine comprising:

• a cylinder having first and second combustion chambers at opposite ends thereof and a third combustion chamber between said ends,
• a first double-acting piston displaceable between said first and third combustion chambers, and a second similar piston displaceable between said second and third combustion chambers,
• each double acting piston including opposite piston heads and a connecting rod between said heads,
• balancing means coupling said two pistons to move symmetrically,
• each of said combustion chambers including an inlet valve and an exhaust valve, said valves being timed to open and close to produce a pressure-volume relationship in each of said combustion chambers
• wherein said exhaust valves each opens and closes about 50.degree..+-.15.degree. before and after LDP, and said inlet valves each open and close respectively at about 30.degree..+-.10.degree. before LDP and 62.degree..+-.10.degree. after LDP, resulting in a pressure in each combustion chamber being below atmospheric for a period at least 10.degree. before LDP and at least 30.degree. after LDP.

In a hybrid vehicle including a frame, wheels, electric motors for driving the wheels, a storage battery for receiving electric current and for energizing said motors, and control means for operating said vehicle and components thereof, the improvement of a double-acting tandem free-piston engine-alternator for charging said battery, said engine-alternator comprising:

• a housing including a cylinder having first and second combustion chambers at opposite ends thereof and a third combustion chamber between said ends,
• a first double-acting piston displaceable between said first and third combustion chambers, and a second similar piston displaceable between said second and third combustion chambers,
• each double acting piston including opposite piston heads and a connecting rod between said heads,
• a linear alternator operable with each piston, each linear alternator comprising stator and runner parts, one of these parts secured to said rod and the other of said parts secured to the housing adjacent said rod,
• balancing means coupling said two pistons to move symmetrically,
• each of said combustion chambers including an inlet valve and an exhaust valve, said valves being timed to open and close to produce a pressure-volume relationship in each of said combustion chambers wherein said exhaust valves of each combustion chamber open and close at a similar position of the corresponding piston, said position being 50.degree..+-.20.degree. before and after lower dead position (LDP) of said piston and said inlet valves for each combustion chamber open and close respectively at about 30.degree..+-.20.degree. before LDP and 62.degree..+-.20.degree. after LDP.

A double-acting tandem free-piston engine comprising:

• a housing including a cylinder having first and second combustion chambers at opposite ends thereof and a third combustion chamber between said ends,
• a first double-acting piston displaceable between said first and third combustion chambers, and a second similar piston displaceable between said second and third combustion chambers,
• each double acting piston including opposite piston heads and a connecting rod between said heads,
• balancing means coupling said two pistons to move symmetrically,
• each of said combustion chambers including an inlet valve and an exhaust valve, said valves being timed to open and close to produce a pressure-volume relationship in each of said combustion chambers wherein said exhaust valves each open and close during the same amount of piston displacement before and after LDP, and said inlet valves each opens at more piston displacement than for said exhaust valve and each closes at greater piston displacement than for said exhaust valve.