Four cycle engine

Details Four cycle engine Four cycle engine

1999-09-14

2001-05-01

McMahon, Marguerite (Department: 3747)

Internal-combustion engines

Particular piston and enclosing cylinder construction

Cylinder head

Reexamination Certificate

active

06223709

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a four-cycle engine including a secondary air supply passage for introducing secondary air into an exhaust port.
2. Description of the Background Art
Japanese Patent Laid-open No. Hei 9-324624 shows a secondary air supply passage for introducing secondary air into an exhaust port of a cylinder head. The secondary air supply passage connects a reed valve chamber provided in the cylinder head cover to the exhaust port provided in the cylinder head. The connecting section between the cylinder head and cylinder head cover is sealed with a knock pin.
It is known that a positioning knock pin is used to position a cam holder in the cylinder head. Further, there are some structures that use a part of a bolt hole for tightening the cam holder and provide a knock pin at another position apart from the bolt hole.
Incidentally, in the case where the bolt hole is used as a knock pin for positioning the cam holder, it is impossible to bring the bolt close to the camshaft, as the diameter of the knock pin becomes larger. Moreover, making the positioning knock pin separate from the bolt hole will necessitate a dedicated boss, thereby increasing the weight of the engine.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve one or more of the drawbacks associated with the background art.
It is a further object of the present invention to provide a simplified cylinder head, cam holder, and cylinder head cover.
It is a further object of the present invention to reduce the number of knock pins needed by having the knock pins serve a dual function of positioning and sealing the secondary air supply passages.
It is a further object of the present invention to provide an arrangement whereby the cylinder head cover and cam holder can be more compact and more easily manufactured.
These and other objects of the present invention are provided by an engine comprising: a cylinder head body having a cam holder mating surface; a cam holder attached to said cylinder head body and abutting said cam holder mating surface; a cam shaft interposed between said cylinder head body and said cam holder; a first passage formed in said cylinder head body; and a second passage formed in said cam holder, communicating with said first passage to pass secondary air into said cylinder head body.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.


REFERENCES:
patent: 4417442 (1983-11-01), Ikenoya et al.
patent: 4450684 (1984-05-01), Otani et al.
patent: 4476676 (1984-10-01), Ikenoya et al.
patent: 4499724 (1985-02-01), Ikenoya et al.
patent: 4727717 (1988-03-01), Ikenoya et al.
patent: 5657628 (1997-08-01), Takeuchi
patent: 5704315 (1998-01-01), Tsuchida et al.
patent: 55-146224 (1980-11-01), None
patent: 57-13213 (1982-01-01), None
patent: 9-324624 (1997-12-01), None

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