Breather structure for four cycle engine

Details Breather structure for four cycle engine Breather structure for four cycle engine

1999-09-14

2001-05-29

McMahon, Marguerite (Department: 3747)

Internal-combustion engines

Charge forming device

Crankcase vapor used with combustible mixture

Reexamination Certificate

active

06237577

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a breather structure for a four cycle engine.
2. Description of the Background Art
As a breather structure for a four cycle engine, a head cover and a breather plate together constitute a breather chamber. A chimney-like projection is provided on the breather plate for preventing oil from flowing into the breather chamber. An alternative breather structure utilizes a plate with a hole formed therein which do not require a chimney-like projection.
The oil scattered by a cam is likely to fall in the breather chamber. Therefore, the breather chamber has a complicated structure in order to ensure its effective performance. Also, although the provision of a chimney-like projection on the plate is effective in preventing oil invasion, it results in a complicated plate and an increased cost.
SUMMARY OF THE INVENTION
In order to solve the above problem, a partition is formed which is integrated with a cam holder for separating the cam holder into upper and lower spaces. The upper space of the cam holder and the partition are used as a breather chamber. Accordingly, a separate breather plate does not need to be provided. This allows easy formation of a breather chamber having a simple structure.
The breather chamber inlet and a separated oil returning hole are formed on the partition. These openings can be formed when the cam holder is formed. The breather chamber inlet and the separated oil returning opening are formed between intake and exhaust cam shafts, and freedom for positioning the openings is increased. The intake/exhaust cam holder is integrally formed with the partition, and they can be formed easily. However, these elements may be formed separately.
A pair of partitions may by formed above and below the cam holder, such that a breather chamber can be formed into two-story structure. A plate is provided for further separating the breather chamber, and oil separation ability can be improved.
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: 4607604 (1986-08-01), Kanoh et al.
patent: 4848170 (1989-07-01), Inagaki et al.
patent: 4922881 (1990-05-01), Tamba et al.
patent: 5664549 (1997-09-01), Hutchins

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