Cylinder head of a DOHC type engine

Details Cylinder head of a DOHC type engine Cylinder head of a DOHC type engine

1999-09-14

2001-03-20

McMahon, M. (Department: 3747)

Internal-combustion engines

Particular piston and enclosing cylinder construction

Cylinder head

Reexamination Certificate

active

06202617

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylinder head of a DOHC (Double Overhead Camshaft) type engine.
2. Description of the Background Art
A cylinder head of a DOHC engine is described in Japanese Patent No. 2584601. The cylinder head includes a tightening bolt for a cam holder, which is tightened in a direction at right angles to a mating surface of the cylinder head and the cam holder.
Providing a cylinder head with such a structure is unfavorable to maintenance performance because the tightening bolt overhangs an extension line of the plug hole. This is also unfavorable to making the space between the air intake and exhaust camshafts narrower and the cylinder head more compact. Moreover, this problem will be further exasperated if such a structure is adopted that the mating surface of the cam holder and the cylinder head is inclined with respect to the mating surface of the cylinder head and the cylinder.
FIG. 3
shows another structure in accordance with the background art. In
FIG. 3
, a cam holder mating surface c between a cylinder head a and a cam holder b is inclined with respect to a cylinder head mating surface d between the cylinder head a and the cylinder (not shown in FIG.
3
). A head gasket e is located adjacent the cylinder head mating surface d.
A lower plug hole f is provided in the cylinder head a at a right angle to the cylinder head mating surface d. An ignition plug g is located inside the lower plug hole f. An electrode section of the ignition plug g reaches to a combustion chamber h.
An upper plug hole k communicates with the lower plug hole f. The upper plug hole k is provided in the cam holder b. The upper plug hole k is formed at a right angle to the cam holder mating surface c, so that the upper plug hole f is bent relative to the lower plug hole f.
An air intake side camshaft m and an exhaust side camshaft n are arranged on the cam holder mating surface c. The air intake side camshaft m and an exhaust side camshaft n are located on either side of the lower plug hole f and the ignition plug g. The air intake side camshaft m and an exhaust side camshaft n are held by cam holder tightening bolts p, fixing the cam holder b on the cylinder head a. The cam holder tightening bolts p are provided at right angles to the cam holder mating surface c.
Such a structure makes it difficult to make the cylinder head compact because the external shape of the cam holder b projects toward the inclined direction by the size of the head section of the bolt p. In addition, a part of the cam holder b surrounding the upper plug hole k overhangs an extension line of the lower plug hole f and enters the extension line of the lower plug hole f by a dimension D. This arrangement makes it difficult to install and remove the ignition plug g. Further, the overhang sets a limit on making the air intake side camshaft m and exhaust side camshaft n closer.
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 cylinder head and cam holder which are compact is size.
It is a further object of the present invention to provide a cylinder head and cam holder which allow a pinch angle between an air intake camshaft and an exhaust camshaft to be small.
It is a further object of the present invention to provide a cylinder head and cam holder which make maintenance operations on an ignition plug easier.
These and other objects are accomplished by providing a cylinder head for an internal combustion engine comprising: a cylinder head body; a cam holder mating surface formed on one side of said cylinder head body; a cylinder mating surface formed on another side of said cylinder head body; and at least one threaded bolt hole formed in said cam holder mating surface and extending into said cylinder head body perpendicular to said cylinder mating surface.
Further, these and other objects are accomplished by providing a cylinder head for an internal combustion engine comprising: a cylinder head body; a cam holder mating surface formed on one side of said cylinder head body; a cylinder mating surface formed on another side of said cylinder head body; an ignition plug hole formed in said cylinder head body and having an axis of extension; and at least one threaded bolt hole formed in said cam holder mating surface and extending into said cylinder head body parallel to said axis of extension.
Moreover, these and other objects are accomplished by providing an internal combustion engine comprising: a cylinder head body; a cam holder body abutting said cylinder head body at a cam holder mating surface formed on one side of said cylinder head body; a cylinder mating surface formed on another side of said cylinder head body; a first threaded bolt hole formed in said cylinder head body; a second threaded bolt hole formed in said cam holder and aligned with said first threaded bolt hole, wherein said first and second threaded bolts holes extend in a direction at a right angle relative to said cylinder mating surface; and a bolt engaged within said first and second threaded bolt holes to attach said cam holder to said cylinder 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: 4709667 (1987-12-01), Ichihara et al.
patent: 4754729 (1988-07-01), Abe et al.
patent: 4757789 (1988-07-01), Laine
patent: 4879980 (1989-11-01), Piazzo
patent: 5003958 (1991-04-01), Yoneyama et al.
patent: 5080057 (1992-01-01), Batzill et al.
patent: 5535714 (1996-07-01), Aoyama et al.
patent: 5875754 (1999-03-01), Ickinger
patent: 5957104 (1999-09-01), Ohsawa
patent: 2584601 B2 (1996-11-01), None

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