Oil pump attachment structure for engine

Details Oil pump attachment structure for engine Oil pump attachment structure for engine

1999-09-08

2001-01-30

Thorpe, Timothy S. (Department: 3746)

Pumps

Motor driven

Including means for facilitating assembly or disassembly of...

C123S1950HC, C123S090160, C123S041440, C074S604000, C074S00700R

Reexamination Certificate

active

06179582

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oil pump attachment structure for an engine and more particularly, it relates to an oil pump attachment structure for attaching an oil pump coaxially driven by a crankshaft.
2. Description of the Related Art
As an earlier structure for attaching the oil pump coaxially driven by the crankshaft, there is disclosed an attachment structure where a pump housing is carried inside a front cover for covering a timing chain and disposed between the front cover and a sprocket for a timing chain (Japanese Patent Publication No. 5-059924).
There is also another structure where a pump housing is disposed between the sprocket for the timing chain and a cylinder block, while the pump housing is either projected from the cylinder block for fixture or embedded in a recess formed on a front side of the cylinder block.
However, in case of the attachment structure allowing the front cover to carry the pump housing, the pulsation produced when operating the oil pump directly oscillates the front cover to cause the noise to radiate from the front side of the front cover, so that the engine noise is increased on the front side of the engine disadvantageously.
In case of the structure where the pump housing is disposed between the sprocket for the timing chain and the cylinder block, the running line of the timing chain is apart from the front face of the cylinder block due to the provision of the pump housing. Therefore, the driving force of the timing chain is applied on a camshaft's portion having a large overhang from journals supporting a camshaft while the whole length of the cylinder head is increased. Consequently, there is a possibility of causing the damping performance to be deteriorated due to the reduced rigidity of the camshaft and the journals or causing the weight of the cylinder block to be increased in order to ensure the rigidity of the camshaft and the journals.
In case of the structure where the pump housing is embedded in the front side of the cylinder block, there is produced a problem of causing the cylinder block to be large-sized.
SUMMARY OF THE INVENTION
Under such a circumstance, it is an object of the present invention to provide an oil pump attachment structure for an engine, which is capable of preventing the pulsation generated at the operation of the oil pump from propagating to the front cover and avoiding the running line of the timing chain from projecting forward thereby preventing the cylinder block from being large-sized.
According to the invention, the above-mentioned object is accomplished by an oil pump attachment structure for an engine having a valve system where at least one camshaft is driven by a crankshaft through at least one timing chain, the oil pump attachment structure comprising:
an oil pump coaxially driven by the crankshaft, for supplying oil to respective engine sections, the oil pump including a pump housing;
wherein the pump housing is disposed between a front cover for covering the timing chain and a sprocket for the timing chain, while leaving a clearance relative to the front cover; and
wherein the pump housing is fastened to a cylinder block of the engine so as to straddle the timing chain.
Since the pump housing is fastened to the cylinder block and the clearance is defined between the pump housing and the front cover, the pulsation produced during the operation of the oil pump is not transmitted to the front cover directly. Therefore, the noise radiated from the front face of the front cover is reduced thereby to decrease the noise occurring on the front side of the engine.
The above and other features and advantages of this invention will become apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference to the attached drawings showing one preferred embodiment of the invention.


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patent: 5758612 (1998-06-01), Tsuzuku et al.
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patent: 5951264 (1999-09-01), Hori et al.
patent: 5-59924 (1993-03-01), None

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