Internal-combustion engines – Two-cycle – Pump compression
Patent
1996-06-19
1997-12-09
Okonsky, David A.
Internal-combustion engines
Two-cycle
Pump compression
123 71R, F02B 7528
Patent
active
056948913
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine having a working cylinder within which is a reciprocatable working piston. The piston is connected by a piston rod to a second piston which is reciprocatable within a supercharge cylinder. The common piston rod is connected with the crank drive of the internal combustion engine. Corresponding inlet, outlet, and connecting channels are provided on the working cylinder and on the supercharge cylinder.
Such an internal combustion engine is known from British Patent No. 1,467,394 (FIG. 6). In that known internal combustion engine, a cylinder body is closed by a cylinder head and is divided by first and second partitions into a working cylinder, a supercharge cylinder and a crank shaft housing. Pistons connected by a common piston rod to the crank drive are arranged in the working cylinder and in the supercharge cylinder, respectively. In this connection, an air inlet opening is situated on the supercharge cylinder in the vicinity of the top dead center and is provided with a valve which permits flow into the supercharge cylinder. An air outlet opening is also provided and is connected by a connecting line to the working cylinder at a location such that the air inlet opening into the working cylinder is unblocked at the bottom dead center of the working piston in the same way as an exhaust channel which is also arranged in the working cylinder. Upon upward movement of the two pistons, air which had been previously drawn in above the piston of the supercharge cylinder is compressed and is used below the working cylinder to dilute the combustion gases still remaining in the exhaust system.
At the same time, a fresh gas mixture is drawn into the supercharge cylinder below the supercharge piston via a check valve which permits a flow into the supercharge cylinder. This inlet opening for the mixture is arranged in the vicinity of the bottom dead center of the supercharge piston and is closed when the latter is at bottom dead center. The inlet opening is further connected by a line which connects the space above the supercharge piston with the inlet opening of the working cylinder. Upon the downward movement of the two pistons in the working stroke after ignition, a fresh gas mixture that is already present in the space below the supercharge piston is forced through the connecting line which, in its upper region, still contains a column of air.
Upon unblocking the inlet opening into the working cylinder by the working piston, the column of air first dilutes and scavenges the combustion gases already discharging, whereupon a succeeding column of mixture then enters into the space above the working cylinder and is compressed upon the next stroke. In this way, a better exhaust-gas behavior of the two-stroke-cycle engine is obtained.
In this known internal combustion engine, however, a number of valves are necessary in addition to the ports and inlet openings controlled by the piston, and control of the exhaust gas behavior still requires essential improvement.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an internal combustion engine of the aforementioned type which has further improved exhaust gas behavior.
By the development of the internal combustion engine in accordance with the invention, dependable scavenging of the burned mixture is attained at the bottom dead center position of the working piston by mixing fresh gas which flows with increased pressure from the supercharge cylinder into the working cylinder. Because the fresh gas mixture is fed to the working cylinder with increased pressure, suction losses are avoided and the inlet port of the working piston, which is closed and opened by the working piston, can be of a very slight height and thus have improved controllability. Moreover, because the inlet port of the supercharge cylinder is unblocked only at the end of the supercharge piston moving in the direction of its top dead center position, a vacuum is produced below the superchar
REFERENCES:
patent: 2381832 (1945-08-01), Mansoff
patent: 3053342 (1962-09-01), Mansoff
patent: 4858571 (1989-08-01), Yang
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