Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
1999-08-16
2001-06-26
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
Reexamination Certificate
active
06250275
ABSTRACT:
TECHNICAL FIELD
The present invention relates to lubrication of reciprocating piston internal combustion engines, and, more particularly, to piston pin lubrication within such engines.
BACKGROUND ART
Reciprocating piston internal combustion engines include one or more pistons that are reciprocally disposed within corresponding combustion cylinders. The pistons are interconnected with each other through the use of a rotatable crankshaft. Rotation of the crankshaft causes each piston to reciprocate within its corresponding combustion cylinder. Typically, each piston is pivotally connected to one end of a connecting rod. The connecting rod includes an eye defining an eye bearing that receives a piston pin of the piston such that the connecting rod pivots through a relatively small pivoting angle about the piston pin during reciprocation. The other end of the connecting rod is also pivotally coupled to the crankshaft which also pivots through a relatively small angle. Lubrication of the moving and pivoting parts within an internal combustion engine is essential during operation, as the lubricant eases friction between moving/pivoting parts and aids in the removal of heat. The lubricant generally used is oil. One area where it is desired to provide lubrication in the internal combustion engine is the piston pin of a piston.
It is known to indirectly supply a lubricant such as oil to the piston pin by splashing the oil proximate the piston pin area. In one form, oil that is sprayed onto the piston undercrown area specifically for cooling the piston crown splashes onto the connecting rod eye of the connecting rod. Since the connecting rod eye is disposed about the piston pin, the oil wicks into the connecting rod eye bearing area defined between the piston pin and the connecting rod eye to provide lubrication. While the splash method does supply lubricant to the piston pin area, the amount of lubricant supplied to the piston pin by the splash method may not be satisfactory. Further, the splash method is a passive rather than an active or positive method of providing lubrication to the piston pin and thus is not preferable.
It is also known to supply lubricant to the piston pin via a bore drilled longitudinally through a corresponding connecting rod. The connecting rod bore is in fluid communication with a lubricant supply via the crankshaft. In this manner, pressurized lubricant may be provided to the piston pin such that this is a positive method of lubrication. However, the structural integrity of the connecting rod is compromised by the connecting rod bore itself. Alternatively, if the connecting rod is enlarged to compensate for the rod bore, thereby preserving the structural integrity of the connecting rod, weight and size for example, then become of particular concern. Thus, providing a connecting rod bore for supplying lubricant to the piston pin is not preferable. Additionally, this method is prone to unacceptable oil leakage from the bearing on the crankshaft.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention, an internal combustion engine comprises a housing including a combustion cylinder, a piston including a piston skirt reciprocally disposed within the combustion cylinder and having a piston pin, the piston skirt defining a bottom surface and having a lubrication passage therein, the lubrication passage having an inlet in the bottom surface of the piston skirt and an outlet adjacent the piston pin, a connecting rod including an eye pivotally disposed about the piston pin, the eye having a lubrication bore oriented to provide at least intermittent fluid communication between the piston pin and the outlet of the lubrication passage, and a lubrication applicator adapted to apply lubricant to the inlet of the lubrication passage.
In another aspect of the invention, an internal combustion engine comprises a housing including a combustion cylinder, a piston reciprocally disposed in the combustion cylinder, the piston having a piston skirt defining a bottom end, a piston pin, and a lubrication passage, the lubrication passage having an inlet port at the bottom end of the piston skirt and an outlet port adjacent the piston pin, a bushing disposed about the piston pin, a connecting rod including an eye pivotally disposed about the bushing, the eye having a fluid feed bore providing communication between an outer surface of the eye and an inner surface of the eye, the fluid feed bore in at least intermittent communication with the outlet port of the lubrication passage during piston reciprocation, and a nozzle assembly in fluid communication with an oil gallery and adapted to apply oil to the inlet port of the piston head during piston reciprocation.
In yet another aspect of the invention, a method of lubricating a piston pin of an internal combustion engine having a housing, a combustion cylinder, a piston reciprocally disposed in the combustion chamber and having a piston skirt defining a bottom side and piston pin, and a connecting rod with an eye pivotally radially disposed about the piston pin comprises the steps of, providing a fluid bore in the eye, the fluid bore in communication between the piston pin on an inside surface of the eye and an outside surface of the eye, providing a lubrication passage in the piston skirt, the lubrication passage having an inlet port in the bottom side of the piston skirt and an outlet port adjacent the fluid bore in the eye, providing a lubrication applicator in fluid communication with a lubricant supply, and applying the lubricant via the lubrication applicator to the inlet port of the piston skirt during piston reciprocation, wherein the lubricant is caused to flow from the inlet port into the lubrication passage, out of the outlet port into the fluid bore and onto the outer surface of the piston pin.
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Bock Allyn P.
Kruse Brian K.
Ali Hyder
Caterpillar Inc.
Taylor Todd T.
Wolfe Willis R.
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