JPH0622085Y2 - Push rod guide device for overhead valve type internal combustion engine - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a push rod guide device for an overhead valve internal combustion engine in which a rocker arm is swingably supported by a spherical fulcrum, and a tappet and a rocker arm are connected by a push rod.

[0002]

2. Description of the Related Art In an internal combustion engine in which a rocker arm is swingably supported by a spherical fulcrum, both ends of the rocker arm are in spherical contact with a push rod and a valve rod, respectively. As a result, the rocker arm becomes unstable in the direction perpendicular to the swinging direction, causing lateral shake during engine operation. Therefore, conventionally, a guide member that directly guides the rocker arm and a guide member that indirectly guides the rocker arm by guiding the push rod are provided to prevent lateral shake.

[0003]

However, as a conventional guide member, for example, it is provided integrally or integrally with a cylinder head as in Japanese Utility Model Laid-Open No. 58-163608, or has a special structure such as Japanese Utility Model Laid-Open No. 58-183905. Since the guide plate is provided, the structure is complicated and the assembly work is troublesome.

[0004]

An overhead valve internal combustion engine in which a rocker arm is swingably supported by a spherical fulcrum, and a tappet and a rocker arm are connected by a push rod extending in a direction substantially orthogonal to the rocker arm. ,
Push rod insertion holes are formed in the cylinder head gasket and the cylinder head cover gasket, and each push rod insertion hole is a long hole that is long in a direction substantially parallel to the rocker arm length direction and short in a direction substantially orthogonal to the rocker arm length direction. , Each push rod insertion hole is provided with a push rod guide portion that opposes the push rod insertion hole in the short width direction so as to face the push rod insertion hole at an interval that is slightly larger than the diameter of the push rod. There is.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a cylinder head 2 is fastened to the upper surface of a cylinder 1 via a cylinder head gasket 3, and a cylinder head cover 6 is fixed to the upper surface of the cylinder head 2 via a cylinder head cover gasket 5.
Is fastened.

Reference numeral 7 denotes, for example, a rocker arm for an intake valve, the central portion of which is swingably supported by a lower end spherical surface portion of a spherical fulcrum portion 8. The spherical fulcrum 8 is inserted in the upper half of the stud 9, and is locked by a nut 10 so as not to come out upward. The stud bolt 9 is screwed onto the cylinder head 2 so as to project upward. The rocker arm 7 is in contact with the lower end spherical surface of the spherical fulcrum 8 from below by the elastic force of the valve spring 11.

One end of the rocker arm 7 is formed in a downwardly projecting partial spherical shape and abuts on the upper end of the intake valve 12. The intake valve 12 is axially slidably supported by the cylinder head 2 via a valve guide 13, and is also seated by a valve spring 11 in a spring seat 14
The valve seat 15 is seated on the valve seat 15.

The other end of the rocker arm 7 is formed into a downwardly-opened concave surface and is in contact with the upper end spherical surface of the push rod 16. The push rod 16 extends into the rod insertion chamber 1 a of the cylinder 1 through the rod insertion chamber 2 a of the cylinder head 2 and the rod insertion hole 18 of the cylinder head gasket 3, and is in contact with the upper end portion of the tappet 17. The tappet 17 is slidably supported in the tappet support hole of the cylinder 1, and its lower end is in contact with the cam 19.

In FIG. 2 showing the II-II cross section of FIG. 1, the cylinder head gasket 3 is made of a metal having excellent wear resistance, and the rod insertion hole 18 is formed to be long in the length direction of the rocker arm 7. There is. A pair of rod guide portions 20 is integrally formed with the cylinder head gasket 3 at both side edge portions of the insertion hole 18 in a direction orthogonal to the rocker arm 7.

The guide portion 20 is formed at the same time as the insertion hole 18 by cutting and raising a part of the cylinder head gasket 3 in a double-opening manner as shown in FIG. The distance d between the guide portions 20 is only slightly larger than the diameter of the rod 16, and restricts the rod 16 from swinging in the direction perpendicular to the rocker arm 7. Reference numeral 16 'in FIG. 2 denotes an exhaust push rod, and the exhaust push rod 16' is also formed with a rod insertion hole 18 and a pair of guide portions 20 similar to those for intake.

Further, the cylinder head cover gasket 5
Also, although not particularly shown, the cylinder head gasket 3
The guide portion 20 having the same shape as that of the above is formed.

[0012]

When the engine is operating, the lateral shake of the rocker arm 7 is indirectly controlled by restricting the lateral shake of the push rod 16 by the guide portion 20.

[0013]

[Other Embodiments] (1) As shown in FIG. 4, the cylinder head gasket 3 is formed of a non-metallic material, and a metal grommet-shaped guide portion 20 having excellent wear resistance is provided in the rod insertion hole 18 portion, for example. It may be fixed by caulking or the like.

(2) As for the cylinder head cover gasket 5, the guide portion 20 may be formed integrally with the cylinder head cover gasket 5 by manufacturing it with a metal having excellent wear resistance as in the case of the cylinder head gasket. Alternatively, the cylinder head cover gasket 5 may be made of non-metal, and the metal grommet-shaped guide portion 20 may be fixed by caulking or the like.

[0015]

As described above, according to the present invention, the rocker arm is swingably supported by the spherical fulcrum, and the tappet and the rocker arm are connected by a push rod extending in a direction substantially orthogonal to the rocker arm. In a valve type internal combustion engine, push rod insertion holes are formed in the cylinder head gasket and the cylinder head cover gasket, and each push rod insertion hole is long in a direction substantially parallel to the rocker arm length direction and in a direction substantially orthogonal to the rocker arm length direction. Each of the push rod insertion holes faces each other at a distance slightly larger than the diameter of the push rod in the short width direction, and the push rod insertion hole restricts the deflection of the push rod in the short width direction. Since the respective guide portions are provided, there are the following advantages.

(1) Compared with the conventional case where a guide device is integrally or integrally provided on a cylinder head which is a large member, a rod guide portion is formed on a cylinder head gasket and a cylinder head cover gasket which are small members. Therefore, the structure is simple and the manufacturing or assembling is easy, and the cost can be reduced.

(2) Since the rod guide portion is made of metal, the durability is good.

(3) Since the guide portion can prevent the push rod and the rocker arm from swinging laterally, the opening and closing operations of the intake valve and the exhaust valve can be maintained in a good state.

(4) Since the push rod insertion hole is a long hole substantially parallel to the length direction of the rocker arm,
The push rod itself is allowed to move in the length direction of the rocker arm due to the rocking of the rocker arm, and the smoothness of the movement of the push rod is maintained. On the other hand, the insertion hole has a short width in a direction substantially orthogonal to the length direction of the rocker arm. Since the swing of the rod is regulated, it is possible to prevent lateral rocking of the rocker arm in the direction orthogonal to the swing direction, and the guide rod guides the push rod and the insertion hole to make direct contact during operation. It is possible to reduce noise and wear caused by.

(5) With respect to one push rod, since the push rod guide portions are provided on both the cylinder head gasket and the cylinder head cover gasket, when the push rod is inserted during assembly, the push rod guide portions are pushed by both guide portions. The insertion direction of the rod is accurately determined, and the work of inserting the tip of the push rod into the recess of the tappet becomes easy.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional view of an overhead valve internal combustion engine to which the present invention is applied.

FIG. 2 is a sectional view taken along line II-II of FIG.

3 is an enlarged partial view taken along the line III-III of FIG.

FIG. 4 shows another embodiment, and is an enlarged partial cross-sectional view of the same portion as FIG.

[Explanation of symbols]

 2 Cylinder head 3 Cylinder head gasket 5 Cylinder head cover gasket 7 Rocker arm 8 Spherical fulcrum 16 Push rod 17 Tappet 18 Rod insertion hole 20 Rod guide

Claims (1)

[Scope of utility model registration request] 1. A cylinder head gasket in an overhead valve internal combustion engine in which a rocker arm is swingably supported by a spherical fulcrum, and a tappet and a rocker arm are connected by a push rod extending in a direction substantially orthogonal to the rocker arm. Also, push rod insertion holes are formed in the cylinder head cover gasket, and each push rod insertion hole is a long hole that is long in a direction substantially parallel to the rocker arm length direction and short in a direction substantially orthogonal to the rocker arm length direction. Opposed to the rod insertion hole at intervals slightly larger than the diameter of the push rod in the width direction,
A push rod guide device for an overhead valve internal combustion engine, characterized in that push rod guide portions for restricting the deflection of the push rod in the widthwise direction of the push rod insertion hole are provided.