Machine element or mechanism – Elements – Cranks and wrist pins
Reexamination Certificate
1999-07-21
2001-03-06
Marmor, Charles A. (Department: 3681)
Machine element or mechanism
Elements
Cranks and wrist pins
C029S888080, C029S893200, C403S359600
Reexamination Certificate
active
06196085
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates a method and mechanism for coupling an accessory, such as an oil pump, directly to an engine crankshaft.
BACKGROUND OF THE INVENTION
It is known in certain engines to mount an oil pump on the front end of an engine offset from the axis of the crankshaft and to drive the oil pump by means of a gear on the crankshaft meshing with a gear on the oil pump that is offset from the axis of the crankshaft, so that the oil pump is driven only indirectly by the engine crankshaft.
It is desirable to be able, in different variants of the same engine, to substitute for the gear driven oil pump a concentric oil pump that is driven directly from the crankshaft. This, however, presents problems because the pumping elements of the directly driven oil pump include a sintered iron rotor that must be fitted over the nose of the crankshaft and coupled for rotation with it. The coupling mechanism on the crankshaft must be sufficiently simple to be incorporated into the manufacturing process of the crankshaft without adding considerably to the manufacturing costs. This consideration precludes the machining of splines or gear teeth on the outer surface of the crankshaft. Furthermore, the coupling mechanism must have a geometric shape that will drive the sintered iron rotor without causing damage or wear and this precludes the use of a Woodruff key. A further consideration is that it is necessary to ensure that the crankshaft should remain usable with a gear driven oil pump.
OBJECT OF THE INVENTION
The invention therefore seeks to provide a means of coupling an accessory directly to an engine crankshaft that mitigates, if not eliminates, at least some of the foregoing problems.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a method of coupling an accessory to an engine crankshaft which comprises forming the end of the crankshaft as a cylindrical nose, forming a splined sleeve and pressing the splined sleeve on the end of the crankshaft with an interference fit.
According to a second aspect of the invention, there is provided an engine having a crankshaft of which one end is formed as a cylindrical nose and a sleeve pressed over the end of the crankshaft with an interference fit, the sleeve being formed with splines for driving an accessory mounted directly on the crankshaft.
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Chimonides Nikos
Smith Damian P.
Cummins Engine Company Ltd
Gron Gary M.
Marmor Charles A.
Parekh Ankur
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