JP2530860Y2 - Valve train for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a valve train for an internal combustion engine, and in particular, to increase the size of a bearing portion of a camshaft journal portion of a four-cycle internal combustion engine and to securely mount a rocker shaft. The present invention relates to a valve operating device for a fixed internal combustion engine.

[Conventional technology]

2. Description of the Related Art An internal combustion engine, for example, a multi-valve internal combustion engine has a valve train having two intake valves and two exhaust valves in one combustion chamber, and these two intake valves are operated by one valve timing. At the same time, the two exhaust valves are simultaneously opened and closed at other valve timings.

In the valve gear, a push rod type in which reliability and the degree of freedom in designing the combustion chamber shape are increased by using a push rod, and a degree of freedom in designing the combustion chamber shape is increased by using an overhead cam, The rocker arm type, which has a high degree of freedom in the design of the intake port, the swing arm type, which uses the swing arm to reduce the equivalent weight on the valve side of the valve train,
There is a direct drive type that drives the tappet directly from directly above the valve without using a rocker arm and has the highest natural frequency and is suitable for a high-speed internal combustion engine.

4 and 5, the valve gear of the internal combustion engine has one end of the rocker arm 120 in contact with a valve stem end of a valve body (not shown) and the other end of the rocker arm 120 with a cam portion 112a of a cam shaft 112. Contact cylinder head 104
And a cam chamber 106 formed by the cylinder head cover 108
The rocker shaft 122 is inserted into a rocker arm bearing 138 and a spring 142 so as to swingably support the rocker arm 120, and is held in the cam chamber 106 by a holding portion 144. At this time, the side surface of the rocker arm 120 was pressed against the side surface of the holding portion 144 by the biasing force of the spring 142, and the rocker arm 120 was positioned by the holding portion 144, and was fixed to the cylinder head by the mounting bolt 146.

Further, as other valve gears for internal combustion engines,
As disclosed in Japanese Unexamined Patent Publication No. 62-124202, there is a type in which the direction of fastening of a bolt for fixing a rocker shaft to a bracket matches the direction of a force acting on the rocker shaft when the valve is seated at the time of maximum rotation of the internal combustion engine. Was.

[Problems to be solved by the invention]

By the way, in the conventional valve gear of an internal combustion engine, a hole for fixing the rocker shaft of the cylinder head is provided perpendicular to the upper surface of the cylinder head in order to achieve vibration and sound insulation of the rocker shaft. Are vertically fitted into the fixing holes via the holding portions.

As a result, the bearing portion of the camshaft journal located near the fixing hole of the rocker shaft provided in the cylinder head is reduced when the fixing hole of the rocker shaft is formed, and the holding force of the camshaft is reduced. The camshaft cannot be held sufficiently, which is disadvantageous in practical use.

[Purpose of the invention]

Therefore, an object of the present invention is to realize a valve train for an internal combustion engine that can sufficiently secure a bearing portion of a camshaft journal portion in a cylinder head and can improve a holding force of a camshaft.

[Means for solving the problem]

In order to achieve this object, the present invention provides a valve operating mechanism for an internal combustion engine in which a rocker arm that swings around a rocker shaft by rotation of a camshaft is provided and a valve body is pressed by the rocker arm to open and close the valve body. In the device, a holding portion which is fastened by a fixing bolt is provided on an upper portion of a cylinder head of the internal combustion engine, and the cam shaft is supported by the holding portion and provided.
The bearing portion of the camshaft journal portion is formed by a bearing surface of a camshaft and a bolt hole for attaching the holding portion, and the rocker is formed between the ignition plug hole formed in the cylinder head and the bolt hole. A through hole for accommodating a shaft is provided, and a fixing hole for the rocker shaft is provided which is connected to the through hole so as to enlarge a bearing portion of the camshaft journal portion and is inclined along an inclination direction of a spark plug hole. It is characterized by having.

[Action]

With the configuration as described above, when mounting the valve train of the internal combustion engine, the rocker shaft supporting the rocker arm so as to be swingable is mounted on the cylinder head,
A camshaft contacting a predetermined portion of the rocker arm is mounted on a bearing of a camshaft journal provided near a mounting portion of the rocker shaft.

At this time, the fixing hole of the rocker shaft is provided between the ignition plug hole and the bolt hole formed in the cylinder head so as to be inclined along the inclination direction of the ignition plug hole. The bearing portion of the camshaft is sufficiently secured, and the holding force of the camshaft is improved.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 to 3 show an embodiment of the present invention. 1 to 3, reference numeral 2 denotes an internal combustion engine, and reference numeral 4 denotes a cylinder head. The internal combustion engine 2 has a cylinder block (not shown) and a cylinder head 4. A cylinder head cover 8 is fixed on the upper surface of the cylinder head 4 to form a cam chamber 6.

In the cam chamber 6, a camshaft 12 of the valve train 10 is disposed so as to be directed in a predetermined direction of the internal combustion engine 2.

In addition, a center pivot type first rocker arm 16 is provided according to the number of intake valves 14 to open and close the valves, for example, the intake valves 14, and a first rocker arm 16 is provided according to the number of exhaust valves 18 to open and close the exhaust valves 18. Two rocker arms 20 are provided. These first and second rocker arms 16, 20
Are rotatably supported by the rocker shafts 22, respectively. One end portion of the first rocker arm 16 is in contact with the cam portion 12a of the camshaft 12, and the other end portion presses the valve stem end 14a of the intake valve 14. The upper surface of the second rocker arm 20 has a cam portion 12a of the camshaft 12.
And the other end portion presses the valve stem end 18a of the exhaust valve 18.

Further, a combustion chamber 24 is provided at a lower portion of the cylinder head 4,
An ignition plug hole 26 communicating from the upper side of the cylinder head 4 to the combustion chamber 24 is provided.

A bearing 28 of a camshaft journal that rotatably supports the camshaft 12 is provided on the upper surface of the cylinder head 4 and near the ignition plug hole 26. The bearing portion 28 is formed by a curved bearing surface 30 that comes into contact with the camshaft 12 and bolt holes 32 for camshafts provided at both end portions of the bearing surface 30.

Further, a holding portion (not shown) which is fastened by a fixing bolt (not shown) is provided above the cylinder head 4 of the internal combustion engine 2, and the cam shaft 12 is supported by the holding portion. A fixing bolt (not shown) is screwed into the hole 32 and fixed.

A through-hole 36 for accommodating the rocker shaft 22 is provided between the ignition plug hole 26 formed in the cylinder head 4 and the bolt hole 32 for the camshaft, and the bearing 28 of the camshaft journal is made large. In order to connect with the through hole 36 and to incline along the direction of inclination of the spark plug hole 26, a fixing hole 34 of the rocker shaft 22 is provided for the sake of simplicity.

That is, in order to separate the fixing hole portion 34 from the camshaft bolt hole portion 32 of the bearing portion 28, the ignition plug hole 26 is approached between the bearing portion 28 and the spark plug hole 26, A fixing hole 34 is provided to be inclined substantially parallel to 26.

That is, in order to separate the fixing hole portion 34 from the camshaft bolt hole portion 32 of the bearing portion 28, the ignition plug hole 26 is approached between the bearing portion 28 and the spark plug hole 26, A fixing hole 34 is provided to be inclined substantially parallel to 26.

 Next, the operation will be described.

When the valve train 10 of the internal combustion engine 2 is mounted, a rocker shaft 22 that swingably supports the first and second rocker arms 16 and 20 is mounted on the cylinder head 4 and the first and second rocker arms 16 and 20 are mounted. The camshaft 12 contacting the predetermined portion 20 is mounted on a bearing 28 of the camshaft 12 provided near the mounting portion of the rocker shaft 22.

At this time, the fixing hole 34 is made to approach the spark plug hole 26 and to be substantially parallel to the spark plug hole 26.
Of the camshaft 12
The width of 28 is sufficiently ensured, and the holding force and attachment of the camshaft 12 are improved.

Thereby, the bearing portion 28 of the camshaft 12 can be sufficiently secured in the cylinder head 4, and the holding force of the camshaft 12 can be improved, which is practically advantageous.

As shown in FIG. 3, since the axial force of the rocker shaft 22 is applied in the oblique direction C, the axial force applied to a bolt (not shown) screwed into the fixing hole 34 is reduced as compared with the conventional case. Can be. Further, since the structure for supporting the camshaft 12 and the rocker shaft 22 is compact, the cylinder head 4 can be downsized.

[Effect of the invention]

As described above in detail, according to the present invention, a holding portion fastened by a fixing bolt is provided on an upper portion of a cylinder head of an internal combustion engine, and a camshaft is supported and provided by the holding portion. Part is formed by a bearing surface of a camshaft and a bolt hole for attaching a holding part, and a through hole for accommodating a rocker shaft is provided between an ignition plug hole and a bolt hole formed in a cylinder head. Since the rocker shaft fixing hole which is connected to the through hole and is inclined along the inclination direction of the ignition plug hole is provided so as to enlarge the bearing of the shaft journal, the bearing of the camshaft journal is connected to the cylinder head. Can be secured sufficiently, and the camshaft holding force can be improved, which is practically advantageous and screwed into the fixing hole. It is possible to reduce the axial force applied to the fixing bolts. Further, since the support structure for the camshaft and the rocker shaft is compact, the cylinder head can be downsized.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a schematic sectional view of a cylinder head of an internal combustion engine, FIG. 2 is an enlarged plan view of a main part of the cylinder head of the internal combustion engine, and FIG. FIG. 2 is a schematic explanatory diagram of the valve gear of FIG. 4 and 5 show the prior art of the present invention, FIG. 4 is a schematic plan view of the internal combustion engine, and FIG. 5 is a schematic front view of the internal combustion engine. In the figure, 2 is an internal combustion engine, 4 is a cylinder head, 6 is a cam chamber, 8 is a cylinder head cover, 10 is a valve gear, 12
Is a camshaft, 14 is an intake valve, 16 is a first rocker arm, 18 is an exhaust valve, 20 is a second rocker arm, 22 is a rocker shaft, 24 is a combustion chamber, 26 is a spark plug hole, 28 is a bearing, and 30 is a bearing. Surface, 32 is a bolt hole for camshaft,
34 is a fixing hole.

Claims (1)

(57) [Scope of request for utility model registration] 1. A valve operating apparatus for an internal combustion engine, wherein a rocker arm that swings around a rocker shaft by rotation of a camshaft is provided and a valve body is pressed by the rocker arm to open and close the valve body. A holding portion fastened by a fixing bolt is provided at the upper portion of the cylinder head, and the cam shaft is supported and provided by the holding portion. The bearing portion of the cam shaft journal portion connects the bearing surface of the cam shaft to the bearing surface of the cam shaft. A bolt hole for attachment, a through hole for accommodating the rocker shaft is provided between the ignition plug hole formed in the cylinder head and the bolt hole, and a bearing for the camshaft journal is enlarged. To the through hole and along the inclination direction of the spark plug hole. A valve gear of an internal combustion engine, characterized in that a fixing hole of the rocker shaft.