Internal-combustion engines – Multiple cylinder – Cylinders radiating
Reexamination Certificate
2000-08-28
2001-07-10
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Multiple cylinder
Cylinders radiating
C123S054400, C123S054500
Reexamination Certificate
active
06257178
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an internal combustion engine for a motorcycle, with two or more single cylinders arranged in a plane approximately normal to a crankshaft, each cylinder accommodating a reciprocating piston and the pistons acting via connecting rods on the same crank of the crankshaft supported in a crankcase.
DESCRIPTION OF THE PRIOR ART
In U.S. Des. Pat. No. 294,264 an internal combustion engine for motorcycles is described which includes two cylinders arranged radially to a crankshaft in V-type fashion, each cylinder acting on a crank via a connecting rod. This type of engine features great compactness and a very short overall length, so that it can be mounted transversely in a motorcycle. For reasons of layout and space the cubic capacity per cylinder is limited. The total cubic capacity could only be increased by adding more cylinders, which would increase the engine's overall length, however.
Another alternative known in the art is the use of three cylinders which are radially positioned relative to the engine crankshaft, where the pistons sliding in the cylinders act on a common crank of the crankshaft by means of individual connecting rods. Such an internal combustion engine whose cylinders are arranged in the shape of a W, is described in U.S. Pat. No. 5,765,451. Engines with W-type cylinder arrangement, where the cylinders are positioned essentially in a plane normal to the crankshaft, will also permit a most compact design with very short overall length. Compared to the V-engine, the additional cylinder will improve the engine's running characteristics and significantly increase its cubic capacity while the small size will be maintained. The large piston-swept volume will permit high engine performance at comparatively low rpm, combined with a typical, full, comparatively low-frequency engine sound.
The different properties of V- and W-engines will appeal to different groups of consumers.
To meet the demand for V-engines on the one hand and W-engines on the other, separate production and distribution systems would have to be set up under conventional conditions, which would require considerable production and logistics efforts and involve high manufacturing costs.
SUMMARY OF THE INVENTION
It is an object of the invention to avoid the above disadvantages and to reduce the manufacturing costs for an internal combustion engine of the afore-mentioned type.
In the invention this object is achieved by using modular components for universal use with at least two different cylinder arrangements. Preferably, the crankcase has a body, which, apart from the flange face for the cylinders, is designed for at least a first and a second cylinder arrangement, the body comprising at least main bearing walls and crankcase side walls. The body may further include a balancer shaft housing configured as an integral part of the crankcase and including balancer shaft bearing walls, and a manual transmission housing including gearshaft bearing walls.
The first cylinder arrangement is formed by at least two cylinders arranged in the shape of a V and the second cylinder arrangement is formed by at least three cylinders arranged in the shape of a W.
Production simplicity and cost-efficiency in manufacturing an internal combustion engine with at least three cylinders in W-type arrangement are considerably improved by providing that at least one component of the group consisting of cylinder head, cylinder, piston, connecting rod, valve train be identical with that of a corresponding engine whose cylinders are arranged in a V.
It is further provided preferably that at least one component of the group consisting of balancer shaft, counterweight, starter, generator, clutch, torque limiter, manual transmission, oil pump, water pump be identical with that of a corresponding engine whose cylinders are arranged in a V. If components of identical type can be used for V- and W-engines, the production process will be simplified considerably, as components may be manufactured and assembled on the same production line. Due to the modular design and component sharing principle large piece numbers will be made possible and manufacturing costs will be reduced. Cost-efficiency will be further improved if at least one component of the group consisting of oil pan, oil cooler, dry sump lubrication, intermediate gear, belt and chain is identical with that of an engine whose cylinders are arranged in a V. Depending on the engine type, carburetor or injection device for multi-point injection or direct injection may be identical in type.
In order to keep production costs for the crankcase down, the proposal is put forward that the body of the crankcase for the W-engine be given the same tooling as that of a corresponding engine with V-type cylinder arrangement. Apart from the cylinder flange the crankcases for both V- and W-engines may be tooled on the same production line.
The large number of shared components has the additional advantage that available production capacities may be fully utilized and downtimes minimized.
V-engines usually have exhaust flange faces that are positioned on the outer side faces of the cylinder heads. To permit the use of identical cylinders and cylinder heads in V-engines and W-engines the proposal is put forward that each cylinder head have a front-side exhaust flange face which is preferably located in a plane normal to the crankshaft axis. The exhaust pipes may thus depart from the front of the engine, which will permit a close spacing of cylinders and reduce the space required by the engine to a minimum.
To permit the use of one and the same crankcase for several engine types, the crankcase features an intermediate gear flange face for connection of an intermediate gear. The intermediate gear, which is configured as a reduction gear, may be designed to be shiftable to enable changing of the reduction ratio.
It may further be provided that the intermediate gear configured as reduction gear be shiftable to enable changing of the reduction ratio, a special advantage being obtained by providing the crankcase with an oil pan flange on its lower side for carrying an oilpan. The oil tank/oil cooler unit forms part of the dry sump lubrication of the engine.
REFERENCES:
patent: 4156409 (1979-05-01), Nakano
patent: 4637354 (1987-01-01), Tominaga et al.
patent: 5230311 (1993-07-01), Kuhn et al.
patent: 6058901 (2000-05-01), Lee
AVL List GmbH
Dykema Gossett PLLC
McMahon Marguerite
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