Internal-combustion engines – Particular piston and enclosing cylinder construction – Piston
Patent
1998-12-11
2000-04-18
McMahon, Marguerite
Internal-combustion engines
Particular piston and enclosing cylinder construction
Piston
1231936, 92193, F01B 3100, F16J 114
Patent
active
060502355
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to mechanical engineering, particularly, to engine designs, and, more particularly, to sealing a cylinder and piston assembly for internal combustion engines.
BACKGROUND OF THE INVENTION
In a conventional cylinder and piston assembly, for example, for two-stroke engines with slot gas distribution, sealing is accomplished by resilient split rings (see Krouglov M. G., Combined Two-Stroke Engines, Moscow, Mashinostroenie, 1977, p.8).
The prior art, however, provides sealing only the annular gap caused by the presence of expansion clearance between a piston and a cylinder wall. With the slot gas distribution which is commonly used in the majority of two-stroke engines, the efficiency of such sealing is inferior as both the combustion products and the pre-compressed charge can flow between blowoff and exhaust ports through the annular gap around the piston, in particular, where the rings meet gas distribution ports. As in two-stroke engines the expansion clearance is relatively large, and increasing the cylinder diameter drastically contributes to the gap area to piston area ratio, the resulting enhanced loss of the fresh charge and increased residual gas ratio prohibit the attainment of high volumetric performance in the two-stroke engines having the cylinder of a diameter above 100 mm and the gas distribution ports arranged in the same lateral plane of the cylinder.
U.S. Pat. No. 2,208,782 discloses a cylinder and piston assembly for an internal combustion engine, comprising a cylinder with gas distribution ports separated by walls, a piston arranged in the cylinder and provided with at least a pair of sealing rings located in grooves and at least a pair of spring pressed elongate members located in the respective grooves on the piston cylindrical surface.
A disadvantage of the above prior art, most closely approaching the present invention, is that the elongate members do not lend themselves to sealing functions as they fail to mate the sealing rings.
SUMMARY OF THE INVENTION
It is an object of the present invention to improve the performance of engines with the slot gas distribution.
The above object is attained by arranging spring pressed elongate members between sealing rings so as to define an enclosed sealed area on the piston cylindrical surface, the spring pressed elongate members being disposed adjacent to the cylinder walls in contact with them.
The object of the present invention is also attained by making a distance between edges of the sealing rings, external to the elongate members, greater than a minimum height of the gas distribution ports.
The object of the present invention is further attained by making recesses for elongate members of a length exceeding a distance between the grooves, the elongate members being arranged so that their ends contact end faces of the sealing rings.
At the ends, the elongate members can have shanks disposed between the piston surface and the sealing rings and contacting inner annular surfaces of the latter.
A length of the elongate members can exceed a distance between the sealing rings, at least one end of the elongate member being located in a split in the sealing ring between its face ends.
A cylinder and piston assembly can be provided with at least one additional ring, the elongate members having lateral grooves, and the additional ring being located between the sealing rings in the piston groove and lateral grooves in the elongate members.
Furthermore, the elongate members can be spring pressed by band expanders arranged along the elongate members.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features and advantages of the present invention will be more clearly understood from the following detailed description of its embodiments taken in conjunction with accompanying drawings in which
FIG. 1 illustrates a cylinder and piston assembly in accordance with the present invention;
FIG. 2 is a sectional view taken through line A--A of FIG. 1;
FIG. 3 is a similar view illustrating the arrangement
REFERENCES:
patent: 1366415 (1921-01-01), Pearson
patent: 1798222 (1931-03-01), Reiland et al.
patent: 1855554 (1932-04-01), La Brie
patent: 2208782 (1940-07-01), Workman
patent: 3656414 (1972-04-01), Muller
Tyo Genya
Zakharov Evgeny Nikolaevich
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