JP2526131Y2 - OHC type engine cylinder head - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a cylinder head of an OHC engine, and more particularly to a cylinder head of an OHC engine which can improve the rigidity of a valve operating mechanism and make the cylinder head compact. .

2. Description of the Related Art In a cylinder head of an engine, components such as an intake valve, an exhaust valve, and a spark plug are attached to each cylinder, and a valve mechanism for operating an intake / exhaust valve is provided. This valve mechanism presses each valve stem of the intake / exhaust valve by a camshaft rotated by driving the engine, presses each valve stem of the intake / exhaust valve, and opens / closes the intake / exhaust valve. is there.

As the valve operating mechanism, a rocker arm type, a direct hit type, or a swing arm type is used depending on the intake / exhaust valve used.

Further, the cylinder head is exposed to high gas pressure and heat load because it is directly exposed to the high temperature and high pressure combustion gas similarly to the cylinder block. For this reason, the characteristics required for the cylinder head are close to those required for the cylinder block, and are often made of cast iron, like the cylinder block.

However, the point that the cylinder head differs from the cylinder block is that the combustion of the air-fuel mixture is completed near the top dead center of the piston, so the amount of heat received is larger than that of the cylinder block, and there is a sliding part with the piston and other parts. Not
It is mainly made of lightweight aluminum alloy casting with excellent heat dissipation.

As a four-stroke internal combustion engine provided with such a DOHC type valve train, for example, as disclosed in Japanese Utility Model Laid-Open No. Sho 60-77707, a bearing half is integrated with a cylinder head and a bearing half. The upper surface consists of a bearing holder that is tightened and fixed with two inner and outer tightening bolts from the inside and outside in the radial direction of the valve operating cam shaft. Machine processing such as counterboring of the axial spring seat surface of the bearing part In this case, a cutter avoiding recess which requires a cutter for performing the above is formed, and a pitch between the outer tightening bolt and the valve operating cam shaft is larger than a pitch between the inner tightening bolt and the valve operating cam shaft.

[Problems to be solved by the invention] By the way, conventional OHC (overhead camshaft)
In the cylinder head of the type engine, the pivot boss of the first rocker arm of the end pivot type, the rocker shaft boss of the second rocker arm of the seesaw type, and the spark plug mounting boss of the spark plug are provided independently. I was

For this reason, the rigidity of the pivot boss, the rocker shaft boss, and the spark plug mounting boss is significantly reduced, and the mounting rigidity of the valve train is reduced.

Further, in order to solve the above-mentioned inconvenience, ribs are provided around the pivot boss portion, the rocker arm boss portion, the spark plug mounting boss portion, and the cylinder head is thickened and reinforced. However, there is a disadvantage that the cylinder head becomes large, the weight increases, the manufacturing cost increases, and it is economically disadvantageous.

[Object of the Invention] In view of the above, an object of the invention is to provide a spark plug mounting boss having a plug insertion hole formed at an angle downward with respect to the cylinder center line in order to eliminate the above-mentioned inconvenience. A rocker shaft boss portion in which a rocker shaft holding hole portion of the second rocker arm is formed near the cylinder center line above the mounting boss portion,
The plug insertion hole and the rocker shaft holding hole are arranged so as to intersect at a substantially right angle, and a spark plug mounting boss is integrally provided on one side of the rocker shaft boss and on the other side of the rocker shaft boss. Is provided integrally with a pivot boss portion in which a pivot side insertion hole portion of the pivot support portion of the first rocker arm is formed, and the rocker shaft holding hole portion and the pivot side insertion hole portion are disposed so as to intersect at a substantially right angle. And, by providing a communicating portion for communicating the rocker shaft holding hole portion and the pivot side insertion hole portion, the rigidity of the rocker shaft boss portion, the pivot boss portion, and the spark plug mounting boss portion is improved, and Achieve an OHC engine cylinder head with improved mounting rigidity, a compact cylinder head, and lighter weight and lower cost. A.

Means for Solving the Problems In order to achieve this object, the present invention provides a cylinder head for an OHC engine having a first rocker arm of an end pivot type and a second rocker arm of a seesaw type as a valve mechanism. , A spark plug mounting boss formed with a plug insertion hole is provided to be inclined downward with respect to the cylinder center line, and the second rocker is located above the spark plug mounting boss and near the cylinder center line. A rocker shaft boss portion having a rocker shaft holding hole portion of the arm is provided, and the plug insertion hole portion and the rocker shaft holding hole portion are disposed so as to intersect at a substantially right angle. The spark plug mounting boss is integrally provided on one side, and the first rocker is provided on the other side of the rocker shaft boss. A pivot boss portion in which a pivot side insertion hole portion of the pivot support portion of the arm is formed integrally, and the rocker shaft holding hole portion and the pivot side insertion hole portion are disposed so as to intersect at substantially a right angle, A communication portion is provided for communicating the rocker shaft holding hole and the pivot side insertion hole.

According to the configuration of the present invention, when forming the cylinder head of the OHC engine, the pivot boss of the first rocker arm, the rocker shaft boss of the second rocker arm, and the spark plug mounting boss of the spark plug. The rigidity of the pivot boss, the rocker shaft boss, and the spark plug mounting boss is improved to improve the mounting rigidity of the valve operating mechanism, and the cylinder head is made more compact and lighter. Cost can be reduced.

Embodiment An embodiment of the present invention will be described in detail and specifically with reference to the drawings.

1 to 3 show an embodiment of the present invention.
In FIG. 1, reference numeral 2 denotes an OHC (overhead camshaft) type engine, 4 denotes a cylinder block, 6 denotes a cylinder head, 8 denotes a cam cap, 52 denotes a first cylinder head cover, and 54 denotes a second cylinder head cover. The engine 2 has a cylinder block 4 in which a cylinder 10 is formed.
An oil pan (not shown) is fixed below the cylinder block 4, and a cylinder head 6 is fixed above the cylinder block 4.

In the engine 2, the piston 12 slides on the cylinder 10,
A combustion chamber 14 is formed by the piston 12 and the bottom surface of the cylinder head 6.

An intake port 16 and an exhaust port 18 communicating with the combustion chamber 14 are formed in the cylinder head 6.

A water jacket 20 is formed on the upper part of the combustion chamber 14 of the cylinder head 6, a valve operating chamber 22 is formed on the upper part of the water jacket 20, and a side part of the water jacket 20 is provided via an upper deck 24. Oil chamber 26
Are formed.

The valve operating chamber 22 of the cylinder head 6 is provided with a valve operating mechanism 27 including intake and exhaust valves 28, 30 and the like. That is,
Intake and exhaust valves 28, 30 that open and close intake and exhaust ports 16, 18
In the valve operating chamber 22, respective stem ends 28a and 30a are provided to protrude. At the end portions of the stem ends 28a, 30a, intake / exhaust valves 28, 30 are connected to intake / exhaust ports 16, 18, respectively.
The spring 32 for urging in the closing direction is contracted.

The intake valve 28 is connected to a cam shaft 36 via an end pivot type first rocker arm 34. The exhaust valve 30 is connected to a camshaft 36 via a seesaw-shaped second rocker arm 38. This camshaft 36
Is provided with a cam 58.

The first rocker arm 34 has a pivot support 40 at one end.
It is swingably supported by a. The pivot supporting portion 40a is inserted into the pivot side insertion hole 46 and is held by the pivot boss portion 40. This pivot side insertion hole
46 is provided at a substantially central portion of the valve chamber 22.

The second rocker arm 38 is swingably supported by the rocker shaft 42. This rocker shaft 42
Is inserted into the rocker shaft holding hole 48 and held by the rocker shaft boss 44.

Further, the cylinder head 6 is provided with a spark plug mounting boss portion 56 in which a plug insertion hole portion 56a for inserting a spark plug (not shown) is formed.

Therefore, in this embodiment, as shown in FIG.
The spark plug mounting boss portion 56 in which the plug insertion hole portion 56a is formed is provided to be inclined downward with respect to the cylinder center line C. The second rocker arm 38 is located above the spark plug mounting boss 56 and near the cylinder center line C.
The rocker shaft boss portion 44 in which the rocker shaft holding hole 48 is formed is provided. The plug center 56c of the plug insertion hole 56a and the shaft center line 48c of the rocker shaft holding hole 48 are disposed to intersect at a substantially right angle.
As shown in FIGS. 2 and 3, a spark plug mounting boss is provided on one side of the rocker shaft boss 44 of the second rocker arm 38.
The pivot boss portion 40 in which the pivot side insertion hole portion 46 of the pivot support portion 40a of the first rocker arm 34 is formed is integrally provided on the other side of the rocker shaft boss portion 44. . The shaft center line 48c of the rocker shaft holding hole 48 and the pivot side insertion hole 46
The pivot center line 46c is disposed to intersect at a substantially right angle. Then, the rocker shaft holding hole 48 and the pivot side insertion hole 46 are communicated by a communication portion 50 as shown in FIG.

Therefore, as shown in FIG. 3, the three boss members of the pivot boss portion 40, the rocker shaft boss portion 44, and the spark plug mounting boss portion 56 are provided integrally at a substantially central portion of the cylinder head 6.

 Next, the operation of this embodiment will be described.

When forming the cylinder head 6, the pivot boss
40 is provided at a substantially central portion of the valve operating chamber 22, and the pivot boss portion
A rocker arm shaft boss portion 44 is integrally provided on 40, a spark plug mounting boss portion 56 is integrally provided on the rocker arm shaft boss portion 44, and a pivot side insertion hole 46 and a rocker arm shaft holding hole are provided. The communication unit 50 communicates with 48.

As a result, in the cylinder head 6 of the engine 2, since the pivot boss 40, the rocker shaft boss 44, and the spark plug mounting boss 56 are provided integrally, the rigidity around these boss portions is improved. Valve train
27 can improve the rigidity of the camshaft
By increasing the degree of freedom around 36, the degree of freedom of the cam profile of the cam 58 can be increased.
Can be rotated at a higher speed.

In addition, since other components such as ribs are not required to increase the rigidity of the cylinder head 6, the layout is simplified by making the cylinder head 6 compact, the weight is reduced, and the manufacturing cost is reduced. be able to.

Further, the core of the oil chamber 26 can be simplified at the time of casting the cylinder head 6, and the running of the molten metal can be improved, so that the casting workability can be improved and the production cost can be reduced.

Further, as shown in FIG. 1, the pivot boss 40, the rocker shaft boss 44, and the spark plug mounting boss 56
And the upper deck portion 24 of the water jacket 20 are integrally formed, so that the cylinder head 6 can be simplified, casting workability can be improved, and manufacturing costs can be further reduced. it can.

[Effects of the Invention] As is clear from the above detailed description, according to the invention,
A spark plug mounting boss having a plug insertion hole is provided to be inclined downward with respect to the cylinder center line, and a rocker shaft holding of a second rocker arm is provided above the spark plug mounting boss and near the cylinder center line. A rocker shaft boss having a hole formed therein is provided integrally with the spark plug mounting portion, and a plug insertion hole and a rocker shaft holding hole are disposed so as to intersect at a substantially right angle. A spark plug mounting boss portion is integrally provided on one side, and a pivot boss portion in which a pivot side insertion hole of a pivot support portion of the first rocker arm is formed integrally on the other side of the rocker shaft boss portion,
The rocker shaft holding hole and the pivot-side insertion hole are disposed so as to intersect at a substantially right angle, and a communication portion that connects the rocker shaft holding hole and the pivot-side insertion hole is provided. The rigidity of the shaft boss, the pivot boss, and the spark plug mounting boss is improved to improve the mounting rigidity of the valve operating mechanism, the cylinder head can be made compact, and the weight and manufacturing cost can be reduced. .

[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 OHC engine, FIG. 2 is an enlarged sectional view of a main part of the cylinder head, and FIG. 3 is an arrow in FIG. III
FIG. 5 is a plan view of a connecting portion of a rocker shaft boss, a pivot boss, and a spark plug mounting boss by the following method. In the figure, 2 is an engine, 4 is a cylinder block, 6
Is a cylinder head, 8 is a cam cap, 10 is a cylinder,
12 is a piston, 14 is a combustion chamber, 16 is an intake port, 18 is an exhaust port, 20 is a water jacket, 22 is a valve operating chamber, 24 is an upper deck section, 26 is an oil chamber, 27 is a valve operating mechanism, and 28 is an intake valve. , 30 is an exhaust valve, 32 is a spring, 34 is a first rocker arm, 36 is a camshaft, 38 is a second rocker arm, 40 is a pivot boss, 42 is a rocker shaft, 44
Is the rocker shaft boss, 46 is the pivot side insertion hole,
48 is a rocker shaft holding hole, 48 is a rocker shaft holding hole, 50 is a communication part, 56 is a spark plug mounting boss, and 58 is a cam.

Claims (1)

(57) [Scope of request for utility model registration] In a cylinder head of an OHC engine having a first rocker arm of an end pivot type and a second rocker arm of a seesaw type as a valve mechanism, a spark plug mounting boss having a plug insertion hole is formed. A rocker shaft boss portion provided to be inclined downward with respect to the cylinder center line and having a rocker shaft holding hole of the second rocker arm formed near the cylinder center line above the spark plug mounting boss portion; The plug insertion hole and the rocker shaft holding hole are disposed so as to intersect at a substantially right angle, and the spark plug mounting boss is integrally provided on one side of the rocker shaft boss, and On the other side of the rocker shaft boss portion, a pivot-side insertion hole of the pivot support portion of the first rocker arm was formed. A bot boss portion is provided integrally, and the rocker shaft holding hole and the pivot side insertion hole are disposed so as to intersect at a substantially right angle, and the rocker shaft holding hole and the pivot side insertion hole are provided. A cylinder head for an OHC engine, which is provided with a communicating portion for communicating.