Two stroke engine with displacer

Details Two stroke engine with displacer Two stroke engine with displacer

1999-08-26

2001-03-13

McMahon, Marguerite (Department: 3747)

Internal-combustion engines

Adjustable combustion chamber

Piston in head adjusted

C123S0480AA

Reexamination Certificate

active

06199520

ABSTRACT:

BACKGROUND—FIELD OF INVENTION
The present invention relates to, reciprocating, two stroke internal combustion engines with displacers.
BACKGROUND—DESCRIPTION OF PRIOR ART
The approach taken by most inventors is that they improve existing designs (crankcase compression or the use of external compression) instead of using a displacer to aid in the intake and exhausting of air and products of combustion. With crankcase compression engines, no scavenging of the cylinder is possible, the volumetric efficiency is low (30 to 50 percent), and the engine is limited to operation at low piston speed (usually less than 1,000 fpm) for economical operation. Other inventors who have introduced displacers into their engines use linkages from the power piston to move the displacer. This includes the present inventor in his patent application “A Two Stroke Regenerative Engine”, Ser. No. 09/354670 dated Jul. 16, 1999. It also includes Hutchinson (1920, U.S. Pat. No. 1,440,150), Wagner (1914, U.S. Pat. No. 1,186,350), and Gile (1920, U.S. Pat. No. 1,335,324). What is needed is a new engine that moves the displacer without a linkage from the power piston. The present invention has no linkage between the power piston and the displacer. The exhaust port is uncovered and recovered by the position of the power piston. The displacer is moved by collision with the power piston and subsequent urging by the power piston, pressure forces and spring forces. The preferred embodiment of the present invention has no linkage between the power piston and the displacer to move the displacer.
SUMMARY
This invention is a two stroke, internal combustion, reciprocating, engine with a displacer, made up of a number of similar working units. Each working unit is comprised of a cylinder that is closed at one end by a cylinder head, and contains a compression chamber, an air inlet valve, a power piston that is connected to a power output shaft, and a displacer. The displacer is a movable wall with a cylinder attached to it. This displacer moves between the power piston and the cylinder head, and the means to accomplish this are: a spring, the urging of the power piston after a collision, and the difference between the internal and external engine pressures. During the compression stroke the pressure inside the engine exceeds the pressure outside of the engine, this pressure difference forces the displacer up against the cylinder head and deforms the spring. During the expansion stroke the pressure difference continues to keep the displacer up against the cylinder head and the spring deformed. Near the end of the expansion stroke the piston reaches the exhaust port. When the piston reaches the exhaust port the pressure is released from inside the engine. Since the spring is connected to the displacer, the spring resuming its undeformed state moves the displacer towards the power piston. While the displacer moves toward the power piston the displacer sucks in the working fluid and pushes the exhaust gases out of the cylinder. After the meeting of the power piston and the displacer and the recovering of the exhaust port, compression begins.
To provide regeneration in an alternative embodiment an alternating flow heat exchanger, called a regenerator, is attached to the displacer.
OBJECTS AND ADVANTAGES
Several objects and advantages of the engine with a displacer are:
(a) The engine compresses the air in the same cylinder that the engine expands the air in.
(b) The engine compresses the air in a portion of the cylinder that is not heated by the hot gases.
(c) The engine allows the compressed air to be cooled.
(d) In an alternative embodiment, the engine saves the heat from the exhaust gases and releases the heat to the compressed air.
(e) In an alternative embodiment, all of the engines valves operate at compressor exit temperature or slightly higher.
(f) The engine exhausts most of the exhaust gases each stroke.
(g) The engine can be operated so that the charge is almost fully expanded.
(h) In the preferred embodiment, the engine has no linkage between the displacer and the power piston.


REFERENCES:
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patent: 5024184 (1991-06-01), Nagano et al.
patent: 5063883 (1991-11-01), Dinges
patent: 5465702 (1995-11-01), Ferrenberg
patent: 5540191 (1996-07-01), Clarke
patent: 5632255 (1997-05-01), Ferrenberg
patent: 0029733 (1987-02-01), None
patent: 0216033 (1989-08-01), None
patent: 406280609 (1994-10-01), None

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