Internal-combustion engines – Two-cycle – Pump and cylinder adjacent
Reexamination Certificate
2000-06-07
2001-11-20
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Two-cycle
Pump and cylinder adjacent
C060S620000
Reexamination Certificate
active
06318310
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an internal combustion engine and more specifically to controlling gas flow through the internal combustion engine having a combustion chamber operating in four-cycle mode and a compression/expansion chamber operating in two-cycle mode.
BACKGROUND ART
Most reciprocating piston internal combustion engines operate by converting heat and/or chemical energy into mechanical energy. Most of these internal combustion engines go through a series of processes known as thermodynamic cycles. Ideals thermodynamic cycles represent work input into a system, work gained from the system, and net work. Examining these ideal cycles shows certain inefficiencies.
In U.S. Pat. No. 3,623,463 issued to De Vries on Nov. 30, 1971, a system describes compressing and combusting an air fuel mixture in one cylinder and expanding and exhausting combustion gasses in a separate cylinder. This system effectively increases the expansion ratio of an engine by pairing a compression/combustion cylinder with an expansion/exhaust cylinder. In the limit these systems are called Atkinson cycle engines. These systems tend to increase engine size. Further, increased friction in a piston type engine may negate gains in efficiency.
In addition to increasing efficiencies, examination of the thermodynamic cycles shows that maximum power available from a given cycle depends on compression ratio instead of expansion ratio. For conventional engines, both expansion ratio and compression ratio are directly related to a cylinder bore and a piston stroke. In a typical four-cycle engine, the cylinder bore and the piston stroke remain constant during compression, expansion, exhaust, and induction cycles. U.S. Pat. No. 1,601,548 issued to Zier et al on Sep. 28, 1926 shows an engine having a compression cylinder having a larger bore taking in air on its down stroke and delivering compressed air to one of two smaller cylinders on its upward stroke. The two smaller cylinders are then used to combust, expand, and exhaust a fuel air mixture. A turbocharger may produce similar power results while reducing size and increasing efficiency relative to using a compression cylinder. However, turbochargers tend to require time for the engine to reach a certain speed before becoming effective. This problem is to referred to a turbo lag.
In an attempt to optimize both power and efficiency, U.S. Pat. No. 5,566,549 issued to Clarke on Oct. 22, 1996 shows an engine having a compression/induction cylinder, a combustion cylinder, and an expansion/exhaust cylinder. Both the compression/induction cylinder and the expansion/exhaust cylinder have larger bores than the combustion cylinder. This engine improves both efficiency and power. However, the increase in efficiency and power requires an increase in engine size. Typically, a user requires only greater efficiency or greater power but not both at the same time.
The present invention is directed to overcoming one or more of the problems set forth above.
DISCLOSURE OF THE INVENTION
In one aspect the present invention discloses a method of operating an engine in two modes. The engine has a combustion chamber and a compression/expansion chamber. Operating the engine in the first mode involves inducing a fluid charge into the compression/expansion chamber and compressing the fluid charge in the compression/expansion chamber. After inducing the fluid charge into the combustion chamber from the compression/expansion chamber, the fluid charge is further compressed in the combustion chamber. Switching the engine to a second operating mode during some predetermined range of operation causes the first combustion chamber to induce the fluid charge into the combustion chamber. After expanding the fluid charge in the combustion chamber, the fluid charge is exhausted into the compression/expansion chamber. The fluid charge is further expanded in the compression/expansion chamber. In another aspect of the invention an internal combustion engine having a first operating mode and a second operating is disclosed. The engine has a compression/expansion chamber and a combustion chamber. A valve system connects the combustion chamber and the compression/expansion chamber. The valve system allows ambient air to enter compression/expansion chamber during the first operating mode. During the second operating mode, the valve system allows ambient air to be inducted into the combustion chamber.
REFERENCES:
patent: 1601548 (1926-09-01), Zier et al.
patent: 1636937 (1927-07-01), Hult
patent: 1638287 (1927-08-01), Burtnett
patent: 2309968 (1943-02-01), Marburg
patent: 3623463 (1971-11-01), Vries
patent: 3880126 (1975-04-01), Thurston et al.
patent: 4159699 (1979-07-01), McCrum
patent: 4174683 (1979-11-01), Vivian
patent: 4202300 (1980-05-01), Skay
patent: 4248198 (1981-02-01), Deutschmann et al.
patent: 4458635 (1984-07-01), Beasley
patent: 4565167 (1986-01-01), Bryant
patent: 4860716 (1989-08-01), Deutschmann
patent: 5072589 (1991-12-01), Schmitz
patent: 5265564 (1993-11-01), Dullaway
patent: 5271229 (1993-12-01), Clarke et al.
patent: 5566549 (1996-10-01), Clarke
patent: 2 071 210 A (1981-09-01), None
Caterpillar Inc.
Kamen Noah P.
Roberson Keith P.
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