Internal-combustion engines – Multiple cylinder – Cylinders radiating
Reexamination Certificate
1998-06-16
2001-04-10
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Multiple cylinder
Cylinders radiating
C124S055000
Reexamination Certificate
active
06213064
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an engine, and in particular to an improved form of engine that is better balanced than the prior art. The invention may be applied to an internal combustion engine, hydraulic or pneumatic pumps and/or motors, a compressor and the like.
BACKGROUND OF THE INVENTION AND PRIOR ART
A problem with known engines, be they IC engines, hydraulic pumps, compressors and the like, that have pistons moving in cylinders, is that a consequence of the piston being driven from a rotating crank is that there are lateral forces that act cyclically on the walls of the cylinder as the piston goes through one cycle of operation. The presence of these lateral forces places a number of restrictions on the design of the cylinders since they must be designed in such a way as to overcome these problems.
SUMMARY OF THE INVENTION
According to the present invention there is provided an engine comprising at least two pairs of pistons and cylinders, said pairs being disposed along mutually orthogonal first and second axes, said pairs being driven by respective first and second cranks, said first and second cranks rotating about a primary crank, said primary crank in turn rotating about a third axis orthogonal to said first and second axes, said first and second cranks having a radius of throw from said primary crank equal to the radius of throw of said primary crank from said third axis.
Preferably a counter-balancing weight is provided opposite said primary crank.
The engine may be a four-cylinder engine having two pairs of orthogonally disposed cylinders, or may be an eight-cylinder engine, having four pairs of cylinders and wherein the cylinders are divided into two groups of four disposed in parallel planes, each plane comprising two mutually orthogonal pairs.
A major advantage of the present invention is that by selecting the correct counter-balancing weight all lateral forces on the cylinders may be eliminated or at least substantially reduced and this permits the use of alternative materials for the cylinder construction. Preferably therefore the cylinders are formed of a ceramic material.
In a particularly preferred embodiment the ceramic cylinders are pre-stressed. This may be achieved by forming the external surface of each cylinder with an at least partially tapering portion, and providing an annular surrounding member having an inner surface tapering in the opposite sense to the external surface of the cylinder, and means being provided for urging said surrounding member such that said tapering surfaces are brought together to generate a radially inwardly directed force. Preferably the urging means comprises spring means.
Viewed from another aspect the present invention provides an engine having four pairs of pistons and cylinders, said four pairs being grouped into two groups of two pairs in each group, the piston and cylinder pairs in each group being disposed on mutually orthogonal first and second axes and being driven by first and second cranks respectively, said first and second cranks rotating about a primary crank, said primary crank rotating about a third axis orthogonal to the first and second axes and comprising three interconnecting sections, junctions between said three sections defining spaces for receiving the respective first and second cranks of said two groups of pistons and cylinders, each said first and second crank having a radius of throw from said primary crank equal to the radius of throw of said primary crank from said third axis, and a counterbalancing weight being provided at each junction opposite said primary crank.
Viewed from still another aspect the present invention provides a cylinder for an engine wherein said cylinder is formed of ceramic material, and wherein said cylinder has an external surface having two portions tapering in opposite senses, and wherein an annular surrounding member having an internal surface tapering in an opposite sense to a first of said two portion-surrounds said first of said two portions, and wherein urging means acts upon said surrounding member whereby the tapering internal surface of said surrounding member and said first tapering portion of said external surface of said cylinder are brought together to generate a radially inwardly directed force, and wherein an annular locking member surrounds said second tapering portion of the external surface of said cylinder and having an internal tapering surface of opposite sense to the said second tapering portion.
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Four Cylinders But Only Four Bearings, Alexander R.M: Engineerin (incl. Machine Shop Magazine), vol. 198, Jul. 24, 1964 , p. 107 XP002070097 issue: 0013-7782.
Benton Jason
McMahon Marguerite
Merchant & Gould P.C.
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