Internal-combustion engines – Multiple piston – common nonrestrictive combustion chamber – Four-cycle
Reexamination Certificate
2000-11-30
2001-11-20
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Multiple piston, common nonrestrictive combustion chamber
Four-cycle
C123S0510BC, C123S055500
Reexamination Certificate
active
06318309
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to an internal combustion engine having two pistons disposed in a common cylinder, and more particularly to such an engine having three combustion chambers in each cylinder of the engine.
2. History of Related Art
Several arrangements have been proposed for internal combustion engines having two double-acting pistons mounted in a common cylinder. In this type of engine, a combustion chamber is provided between each piston and an adjacent cylinder head, and in some arrangements also between the two pistons, thereby providing three combustion chambers per cylinder.
For example, U.S. Pat. No. 2,203,648 issued Jun. 4, 1940 to F. C. Dons describes a two-stroke engine having three combustion chambers formed between, and at the outer ends, of two pistons disposed in a single cylinder. U.S. Pat. No. 2,388,756 granted Nov. 13, 1945 to W. G. Meyers likewise discloses an engine, operating in a two-stroke cycle, with double-acting pistons mounted in a common cylinder. U.S. Pat. No. 2,532,106, issued Nov. 28, 1950 to Theodore Korsgren also describes a two-stroke cycle opposed piston engine having three combustion chambers in each cylinder. Another example of an opposed piston engine, capable of operating in either a two or four-stroke cycle mode is described in U.S. Pat. No. 3,010,440 granted Nov. 28, 1961 to A. Roth.
All of the combustion chambers in each of the above-referenced engines operate contemporaneously in a common, i.e., the same, combustion mode using a predesignated fuel source. Thus, when optimizing engine performance, each of the above-referenced engines are limited to certain advantages provided by the particular operating cycle. For example, the four-stroke cycle has advantages in some operational areas over the two-stroke cycle, such as easier power regulation over wider variations in speed and load, cooler pistons, no fuel loss during exhaust, lower specific fuel consumption, and lower hydrocarbon emissions. The two-stroke cycle advantages, compared with four-cycle engines, include a 50% to 80% greater power output per unit piston displacement at the same speed and twice as many power impulses per crankshaft rotation.
The present invention is directed to overcoming one or more of the problems and limitations inherent in previous opposed piston engines.
SUMMARY OF THE INVENTION
In accord with one aspect of the present invention, an internal combustion engine, having at least one cylinder with spaced-apart ends, includes a cylinder head disposed at each of the spaced-apart ends of the cylinder, and a pair of pistons reciprocatively disposed in the cylinder. Each piston has a first end cooperating with one of the cylinder heads to form respective first and second combustion chambers adapted for operation in a four-stroke combustion mode, and a second end spaced from the respective first ends and cooperating with each other to form a third combustion chamber therebetween that is adapted for selective operation in a two-stroke combustion mode.
Other features of the internal combustion engine embodying the present invention include the reciprocating movement of each piston being selectively adjustable to provide a controllably variable compression ratio in the respective combustion chambers. Other features include each of the cylinder heads having at least one intake valve and at least one exhaust valve. Still an additional feature includes the third combustion chamber having at least one exhaust port and at least one intake port. Yet another feature of the internal combustion engine embodying the present invention includes the engine having a turbocharger in fluid communication with the first, second and third combustion chambers.
REFERENCES:
patent: 639686 (1899-12-01), Parks
patent: 2203648 (1940-06-01), Dons
patent: 2388756 (1945-11-01), Meyers
patent: 2532106 (1950-11-01), Korsgren
patent: 2910973 (1959-11-01), Witzky
patent: 3010440 (1961-11-01), Roth
patent: 3192783 (1965-07-01), Cruzan
patent: 3209736 (1965-10-01), Witzky
patent: 3608530 (1971-09-01), Wenzel
patent: 3866581 (1975-02-01), Herbert
patent: 5025759 (1991-06-01), Wenzel et al.
J. Witzky R. Meriwether and F. Lux; “Piston-Turbine-Compound Engine-A Design and Performance Analysis” Society of Automotive Engineers International West Coast Meeting, pp. 1-11, NY, Argued 1965.
Burrahm Robert Wayne
Hedrick John Craig
McMahon Marguerite
Oliff & Berridg,e PLC
Southwest Research Institute
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