JP2584600B2 - Valve train for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has two intake valves and two exhaust valves facing a combustion chamber, a single camshaft disposed on a cylinder head, and one of the intake valves or exhaust valves is cammed. Open / close drive by a shaft and open / close drive of the other of the intake valve or the exhaust valve by a rocker arm that engages with the camshaft.
The present invention relates to a valve operating device for an SOHC type internal combustion engine having a valve.

[0002]

2. Description of the Related Art A spark plug faces a substantially center of a combustion chamber above a cylinder bore, two intake valves face one half of one side of the combustion chamber, and two exhaust valves face one half of the other side of the combustion chamber. A camshaft is arranged on the cylinder head on the valve axis of one of the intake or exhaust valves, and a single camshaft is provided between the other of the intake or exhaust valves and the camshaft. A rocker arm that is engaged with the camshaft and swings with the rocker arm shaft as a support shaft, the one valve is opened and closed by the rotation of the camshaft, and the other valve is swung by the rocker arm. An SOHC type valve operating device which is opened and closed by movement is known, for example, from Japanese Patent Application Laid-Open No. 56-143322.

[0003]

In an SOHC type internal combustion engine equipped with such a four-valve, if an attempt is made to arrange a spark plug at the center of the combustion chamber in order to suppress knocking and increase combustion efficiency, the spark plug must be connected to the combustion chamber. The spark plug insertion hole interferes with the components that make up the valve train, so the cylinder head width and height must be increased, and the spark plug insertion hole is secured on the cylinder head. Therefore, if a member having the insertion hole is separately provided, there is a problem that the number of parts increases.

SUMMARY OF THE INVENTION The present invention has been devised to solve the above-mentioned problem, and an object of the present invention is to provide a spark plug in the center of a combustion chamber without increasing the number of parts while reducing the size of a cylinder head. An object of the present invention is to provide a four-valve SOHC type valve train in which a plug can be arranged.

[0005]

According to the present invention, in order to achieve the above object, a rock insertion arm formed with a plug insertion hole for inserting a spark plug supports both the rocker arm shaft and the cam shaft. The rocker arm shaft was arranged between the camshaft and the plug insertion hole above the center of the cylinder bore and close to the plug insertion hole.

[0006]

[Function] Since the rocker arm shaft is arranged adjacent to the camshaft arranged on one side, the camshaft arranged on one side is suitable for securing a large space on the rocker arm side and compacting the valve operating mechanism. The freedom of the cam profile design can be improved while securing the degree of freedom of the configuration of the rocker arm, and the camshaft and the rocker arm shaft are both supported by the wall for forming the plug insertion hole. Therefore, the number of parts can be reduced.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a reference example for explaining the present invention will be described. FIG. 1 is a side view of a main part of a cylinder head portion of the reference example, and FIG. 2 is a plan view of the same.

1 is a water-cooled 4-cylinder engine, 3 is a cylinder block, 5 is a cylinder head, and a cylinder block 3
, Four cylinder bores 7 are arranged in a row, a piston 9 is fitted in the cylinder bore 7, a spark plug 13 and two intake valves 15,
15 and two exhaust valves 17, 17 are exposed.

On one side of the cylinder head 5 above the cylinder bore 7, one camshaft 21 is arranged in parallel with the direction 19 in which the cylinder bores 7 are arranged.

[0010] The exhaust valves 17, 17 are deviated and shifted to one side from the center 7A of the cylinder bore to face the combustion chamber 11,
In addition, an axial center 17A is installed vertically between the combustion chamber 11 and the camshaft 21 so as to be substantially parallel to the cylinder bore center 7A.

The exhaust valve 17 is disposed by urging the exhaust port 31 in the closing direction by a valve guide 23, a spring retainer 25, a valve spring 27, and a valve spring seat 29, and a tappet 33 disposed on the top of the exhaust valve 17.
Is engaged with the exhaust valve cam portion 21A of the camshaft 21, the exhaust valves 17, 17 are directly driven by the rotation of the camshaft 21, and the exhaust ports 31, 31 are opened and closed.

The intake valves 15, 15 are deflected toward the other side from the center 7A of the cylinder bore to face the combustion chamber 11,
The shaft center 17A is vertically installed at an angle θ1 with respect to the cylinder bore center 7A.

The intake valves 15, 15 are a valve guide 23, a spring retainer 25, and a valve spring 2 respectively.
7. Intake port 43 by valve spring seat 29
And the intake ports 43, 43 are opened and closed by the intake valves 15, 15 by swinging the two rocker arms 45, 45 engaged with the camshaft 21.

The rocker arm 45 is connected to the camshaft 21.
And a rocker arm shaft 47 disposed at the top of the intake valve 15 in parallel with the cylinder bore arrangement direction 19, and the rocker arm shaft 47 is supported by a rocker arm holder 49.

The rocker arm holder 49 is disposed on the cylinder head 5 so as to be located above the cylinder bore 7 and substantially at the center in the cylinder bore arrangement direction 19, and is disposed between the two rocker arms 45 in the embodiment.

The rocker arm 45 is located at the center 4 in the longitudinal direction.
5A is supported by the rocker arm shaft 47,
A slipper surface 45C at the tip of an arm portion 45B extending from A to the camshaft 21 side is engaged with the intake valve cam portion 21B of the camshaft 21, and extends from the central portion 45A to the side opposite to the arm portion 45B. The adjusting screw 51 at the tip of the arm 45D is engaged with the top of the intake valve 15,
The rotation of the camshaft 21 drives the intake valves 15, 15 via the rocker arm 45 to open and close the intake ports 43, 43.

The rocker arm holder 49 has a bearing 49A having a semicircular bearing surface for supporting the journal of the camshaft 21 and a pair of bearings 49B, 49B having an annular bearing surface for supporting the rocker arm shaft 47.
And a cylindrical portion 49C through which a spark plug insertion hole 53 erected between the two bearing portions 49B, 49B is provided.

The spark plug insertion hole 53 is provided at the shaft center 1.
7A to cylinder bore center 7A at angle θ2 intake valve 1
The cylinder portion 49C is configured to be inclined toward the center of the cylinder head 5 and to be continuous with the spark plug insertion hole 53 of the cylinder head 5 toward the center of the combustion chamber 11.

The rocker arm holder 49 has the both sides of the bearing portion (49A) of the camshaft 21 and the outer portion of the cylindrical portion 49C attached to the cylinder head 5 with bolts 59, respectively.

The spark plug 13 is attached to the cylinder head 5 through the spark plug insertion holes 53 and 55 at substantially the center of the combustion chamber 11, and is provided around the spark plug insertion hole 53 on the lower surface of the rocker arm holder 49. Is provided with a sealing member 61.

In the reference example, the rocker arm shaft 47 is provided with a spark plug plug insertion hole 53 in the bearing portions 49B, 49.
B, the rocker arm holder 49, which is a short axis and is disposed corresponding to the adjacent cylinder bore 7, 7,
Both ends of the rocker arm shaft 47 are supported by the opposing bearing portions 49B, 49B.

In the drawing, reference numeral 62 denotes a rocker arm shaft 47.
And rocker arms 45, 45
A coil spring for biasing the rocker arms 45, 45 by biasing them toward the B, 49B side, and 63 denotes a water jacket.

In this embodiment, the rocker arm holder 49 having the spark plug insertion hole 53 formed integrally with the cylinder head 5 in the upper portion of the cylinder bore 7 is disposed substantially at the center of the cylinder bore 7 as described above. The spark plug 13 can be disposed almost at the center of the combustion chamber 11 without increasing the number of parts while reducing the size of the cylinder head 5.

Next, an embodiment of the present invention will be described with reference to FIGS.

FIG. 3 is a sectional view of a main part of a cylinder head according to the present invention, and FIG. 4 is a plan view of the same.

The members corresponding to the reference example will be described with the same reference numerals. In this embodiment, the rocker arm cylinder head 5 is connected to the camshaft 21 and the spark plug insertion hole 53.
Is different from the reference example in that the rocker arm shaft 47 is constituted by one shaft.

A rocker arm holder 49 forming a plug insertion hole forming wall in which a plug insertion hole 53 for inserting the spark plug 13 is formed. The rocker arm shaft 47 and the camshaft 21 are both supported. The rocker arm shaft 47 is disposed between the plug 21 and the plug insertion hole 53 so as to be close to the plug insertion hole 53.

According to the present embodiment, the operation according to the reference example is
In addition to the effects, the one-sided arrangement of the camshaft ensures a large space on the rocker arm side and the compactness of the valve operating mechanism, and the degree of freedom in the configuration of the valve operating mechanism at the top of the cylinder head is ensured. Because the rocker arm shaft is located adjacent to the camshaft,
Since the length of the rocker arm can be increased, the degree of freedom of the cam profile design can be improved, and the number of components can be reduced since both the camshaft and the rocker arm shaft are supported by the wall for forming the plug insertion hole.

[0029]

As is apparent from the above description, according to the present invention, since the rocker arm shaft is arranged adjacent to the camshaft arranged on one side, a large space on the rocker arm side can be secured and the valve operating mechanism can be made compact. The camshaft suitable for the one side arrangement ensures the freedom of the structure of the valve mechanism at the top of the cylinder head, while allowing the rocker arm to have a large length, improving the freedom of the cam profile design. Since the camshaft and the rocker arm shaft are both supported by the plug insertion hole forming wall, the number of parts can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a cylinder head portion of a reference example.

FIG. 2 is a plan view of the same.

FIG. 3 is a sectional view of a main part of a cylinder head according to the present invention.

FIG. 4 is a plan view of the same.

[Explanation of symbols]

3 ... cylinder block, 5 ... cylinder head, 7 ... cylinder bore, 11 ... combustion chamber, 13 ... spark plug, 15
... intake valve, 17 ... exhaust valve, 21 ... camshaft, 45 ...
Rocker arm, 47: rocker arm shaft, 49: rocker arm holder (plug insertion hole forming wall), 49A: bearing portion, 49B: bearing portion, 53: plug insertion hole.

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location F02P 13/00 301 F02P 13/00 301B

Claims (1)

(57) [Claims] A spark plug is made to face substantially the center of a combustion chamber above a cylinder bore, and two intake valves are made to face one half of one side of the combustion chamber and two exhaust valves are made to face one half of the other side of the combustion chamber. One camshaft for opening and closing the intake valve and the exhaust valve is disposed on a cylinder head on the valve axis of one of the intake valve or the exhaust valve, and the other of the intake valve or the exhaust valve is provided on the other side. An internal combustion engine having a single rocker arm shaft disposed between a valve and a camshaft, and having a rocker arm that engages with the camshaft, swings around the rocker arm shaft as a support shaft, and opens and closes the other valve. In the valve gear of the above, the rocker arm shaft and the cam shaft are both supported on the plug insertion hole forming wall in which the plug insertion hole for inserting the spark plug is formed. Wherein the rocker arm shaft is arranged between the camshaft and the plug insertion hole so as to be close to the plug insertion hole.