JPH07217410A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an SOHC valve system which can reduce a size of a cylinder head and arrange a spark plug in a center portion of a combustion chamber without increasing number of parts. CONSTITUTION:A plug inserting hole part 53 is integrated with a cylinder head 5 which has a cam shaft 21, a rocker arm shaft 47, and an ignition plug 13, for supporting the cam shaft 21 and the rocker arm shaft 47, being adapted to the ignition plug insertion in the vicinity of a rocker arm shaft supporting part 49B. A separable common abutting surface which can divide the plug insertion hole part 53, a cam shaft supporting part 49A, the rocker arm shaft supporting part 49B is formed of a plate 49D passing center axes of the cam shaft supporting part 49A and the supporting part 49B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pair of homogenous engine valves,
The present invention relates to a valve train for an SOHC type internal combustion engine having a single camshaft.

[0002]

2. Description of the Related Art A spark plug is made to face approximately the center of a combustion chamber above a cylinder bore, 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. One camshaft is arranged on the cylinder head on the valve axis of one of the intake valve or the exhaust valve, and a single camshaft is provided between the other valve of the intake valve or the exhaust valve and the camshaft. A rocker arm shaft is provided, and a rocker arm that engages with the cam shaft and swings about the rocker arm shaft is provided.The one valve is opened and closed by the rotation of the cam shaft, and the other valve swings the rocker arm. An SOHC type valve operating device which is opened and closed by motion is known, for example, from Japanese Patent Application Laid-Open No. 56-143322.

[0003]

In an internal combustion engine having four valves provided with such a SOHC type valve operating device, a spark plug should be arranged in the center of the combustion chamber in order to suppress knocking and improve combustion efficiency. If so, there is a problem that the width and height of the cylinder head must be increased because the hole for inserting the spark plug into the combustion chamber interferes with each member constituting the valve operating device. If a member having the insertion hole is provided separately in order to secure the insertion hole for the spark plug, the number of parts increases, and further, it is necessary to individually process the member mounting surface on the upper part of the cylinder head, which causes an increase in the number of steps. Occurs.

The present invention has been devised in order to eliminate the above-mentioned problems, and an object of the present invention is to reduce the number of parts while reducing the size of the cylinder head, and to reduce the number of working steps. Providing a valve device.

[0005]

In order to achieve the above object, the present invention forms a spark plug insertion hole portion for inserting a spark plug in a cylinder head, and supports a cam shaft by an upper surface of a cylinder head and an upper cam holder. The rocker arm shaft is supported by the upper surface of the cylinder head and the upper rocker arm holder, and the upper cam holder mounting surface, the upper rocker arm holder mounting surface and the spark plug insertion hole upper surface on the upper cylinder head surface are formed in the same plane, and the upper rocker arm holder is mounted on the upper rocker arm holder. Formed an ignition plug insertion hole for inserting the ignition plug.

[0006]

Since the cam shaft and the rocker arm shaft are supported by the cylinder head and the plug insertion hole is formed in the cylinder head, each supporting member is not required and the number of parts is reduced and large support is provided. Rigidity and ease of attachment / detachment can be obtained, and since the upper part of the cylinder head is on the same plane, man-hours can be reduced by simultaneous processing. Furthermore, since the upper rocker arm holder has a plug insertion hole, the cylinder It is possible to make the valve operating mechanism compact by effectively utilizing the head upper space.

[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.

Reference numeral 1 is a water-cooled 4-cylinder engine, 3 is a cylinder block, and 5 is a cylinder head.
4 cylinder bores 7 are arranged in a row, a piston 9 is fitted in the cylinder bore 7, and a spark plug 13 and two intake valves 15 are provided in a combustion chamber 11 on the lower surface of the cylinder head 5.
15 and two exhaust valves 17, 17 are exposed.

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

The exhaust valves 17 and 17 are made to deviate to the one side from the cylinder bore center 7A so as to face the combustion chamber 11.
In addition, a shaft center 17A is vertically provided between the combustion chamber 11 and the cam shaft 21 so as to be substantially parallel to the cylinder bore center 7A.

The exhaust valve 17 is disposed by urging the valve guide 23, the spring retainer 25, the valve spring 27, and the valve spring seat 29 in a direction to close the exhaust port 31, and the 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 and 15 are displaced toward the other side from the cylinder bore center 7A so as 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 and 15 include a valve guide 23, a spring retainer 25, and a valve spring 2, respectively.
7, valve spring seat 29 for intake port 43
The intake valves 15 and 15 open and close the intake ports 43 and 43 by swinging two rocker arms 45 and 45 engaged with the camshaft 21.

The rocker arm 45 is the camshaft 21.
The rocker arm shaft 47 is arranged at the top of the intake valve 15 so as to be parallel to the cylinder bore arrangement direction 19, and the rocker arm shaft 47 is supported by the rocker arm holder 49.

The rocker arm holder 49 is arranged above the cylinder bore 7 and substantially in the center in the cylinder bore arrangement direction 19 and is arranged on the cylinder head 5. In the embodiment, it is arranged between the two rocker arms 45, 45.

The rocker arm 45 has a central portion 4 in the longitudinal direction.
5A is supported by the rocker arm shaft 47, and the central portion 45
The slipper surface 45C at the tip of the 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 adjustment screw 51 at the tip of the arm portion 45D is engaged with the top portion of the intake valve 15,
The intake valves 15, 15 are driven via the rocker arm 45 by the rotation of the camshaft 21, and the intake ports 43, 43 are opened and closed.

The rocker arm holder 49 has a bearing portion 49A having a semicircular bearing surface for supporting the journal portion of the cam shaft 21, and a pair of bearing portions 49B, 49B having an annular bearing surface for supporting the rocker arm shaft 47.
And a tubular portion 49C having a spark plug insertion hole 53 provided upright between the bearings 49B and 49B.

The spark plug insertion hole 53 has a shaft center 1
7A to the cylinder bore center 7A Angle θ2 Intake valve 1
It is tilted to the 5 side and is formed toward the center of the combustion chamber 11 continuously with the spark plug insertion hole 53 of the cylinder head 5, and a flange portion 57 is formed at the upper end of the cylinder portion 49C.

The rocker arm holder 49 is attached to the cylinder head 5 by bolts 59 on both sides of the bearing portion (49A) of the camshaft 21 and on the outside of the cylinder portion 49C.

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

In the rocker arm shaft 47, in the reference example, the spark plug plug insertion hole 53 is provided in the bearing portions 49B, 49.
Due to the relationship formed between B, the rocker arm holder 49, which has a short axis and is arranged corresponding to the adjacent cylinder bores 7, 7,
Both ends of the rocker arm shaft 47 are supported by bearing portions 49B and 49B facing each other.

In the drawing, 62 is a rocker arm shaft 47.
The rocker arms 45, 45 are mounted on each bearing 49.
Coil springs for urging the rocker arms 45, 45 by urging to the B and 49B sides, and 63 a water jacket.

This reference example is constructed as described above, and the rocker arm holder 49 integrally formed with the spark plug insertion hole 53 is arranged on the cylinder head 5 above the cylinder bore 7 at the substantially center thereof. It is possible to arrange the spark plug 13 substantially in the center of the combustion chamber 11 while reducing the size of the cylinder head 5 and without increasing the number of parts.

Next, based on the above-mentioned reference example, an embodiment of the present invention will be described with reference to FIGS.

FIG. 3 is a sectional view of a cylinder head portion of the present invention, and FIG. 4 is a plan view thereof.

The members corresponding to the reference example will be described with the same reference numerals. In the present embodiment, the axis 15A between the combustion chamber 11 and the camshaft 21 is located at the cylinder bore center 7A and the angle θ.
The intake valve 15 is vertically installed on one side of the cylinder head 5 with three inclinations, and the intake valve 15 is directly opened / closed by the rotation of the camshaft 21 via the tappet 71, the spring retainer 73, the valve spring 75, the valve seat 77, and the like. Drive it,
The exhaust valve 17 is vertically installed on the other side of the cylinder head 5 with the axis 17A inclined at the cylinder bore center 7A by an angle θ4, and the exhaust valve 17 is provided with a rocker arm 45, a spring retainer 79,
The cam shaft 21 is rotated through the valve spring 81, the valve seat 83 and the like to be opened and closed, and the rocker arm shaft 47 is connected to the plug insertion hole 53 and the exhaust valve 17.
And the rocker arm shaft 47 is configured by one shaft, which is different from the reference example.

A plug insertion hole 49C for inserting a spark plug is formed in the cylinder head 5, and the camshaft 21 is supported by the upper surface of the cylinder head 5 and the upper cam holder of the camshaft support 49A. The rocker arm shaft 47 is supported by the upper surface and the upper rocker arm holder of the rocker arm supporting portion 49B, and the upper surface of the cylinder head, the upper cam holder mounting surface, the upper rocker arm holder mounting surface, and the upper surface of the ignition plug insertion hole 49C are formed in the same plane 49D. Then
An ignition plug insertion hole portion 49C for inserting the ignition plug is formed in the upper rocker arm holder.

The cam shaft and rocker arm shaft are
By being supported by the cylinder head by the half-split support portion, it is possible to reduce the number of parts without requiring each support member, and to achieve easy attachment / detachment and large support rigidity, and also the upper rocker arm holder. Since the plug insertion hole is formed in the cylinder head, the number of parts can be reduced and the space above the cylinder head can be used efficiently to make the valve operating mechanism compact. Furthermore, the cylinder head including the plug insertion hole is also included. Since the upper part of the is coplanar, the number of steps can be reduced by simultaneous processing.

[0029]

As is apparent from the above description, according to the present invention, the cam shaft and the rocker arm shaft are supported by the cylinder head, and the plug insertion hole is formed in the cylinder head. No supporting member is required, the number of parts is reduced, and large support rigidity and easy attachment / detachment can be obtained. Also, since the upper part of the cylinder head is on the same plane, it is possible to reduce man-hours by simultaneous processing. Further, since the plug insertion hole is formed in the upper rocker arm holder, the valve operating mechanism can be made compact by utilizing the space above the cylinder head without waste.

[Brief description of 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 an essential part of a cylinder head portion of 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, 49A ... Support portion, 49B ... Support portion,
49C ... Cylinder (plug insertion hole), 49D ... Mating surface, 5
3 ... Hole for plug insertion.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02P 13/00 301 B

Claims (1)

[Claims] 1. A pair of similar engine valves, a single camshaft, a pair of rocker arms swingably supported by rocker arm shafts for interlocking and connecting these engine valves and camshafts, and between the rocker arms. Is installed in
In an SOHC type internal combustion engine including an ignition plug arranged substantially in the center of the ceiling surface of a combustion chamber, an ignition plug insertion hole for inserting the ignition plug is formed in a cylinder head, and the cylinder head upper surface and an upper cam holder are formed. And the rocker arm shaft is supported by the upper surface of the cylinder head and the upper rocker arm holder, and the upper surface of the cylinder head, the upper rocker arm holder mounting surface, the upper rocker arm holder mounting surface and the upper surface of the ignition plug insertion hole are flush with each other. Formed into a
A valve operating device for an internal combustion engine, wherein the upper rocker arm holder is formed with an ignition plug insertion hole for inserting the ignition plug.