JPH062510A - Four-cycle engine valve drive - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] By reducing the contact area of the cam cap that receives the thrust on the side of the rocker arm, the frictional resistance during rocking of the rocker arm is reduced and the output loss is reduced. To obtain a valve train of a four-cycle engine that can be reduced. [Structure] A side surface of a rocker arm 5 pivotally supported by the rocker shaft 4 is pressed against an end surface of a cam cap 3 through which a rocker shaft 4 mounted on a cylinder head is inserted,
In order to control the thrust of the rocker arm 5, a radial notch 12 is provided on the end surface of the cam cap 3 to reduce the contact area between the rocker arm 5 and the cam cap 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating system for a four-cycle engine which can reduce the frictional resistance of a rocker arm that opens and closes intake and exhaust valves of a four-cycle engine used in an outboard motor or the like.

[0002]

2. Description of the Related Art An outboard motor may use a four-cycle engine as a power source. In a four-cycle engine, the rocker arm is swung by the rotation of the cam of the cam cap that links the intake valve and the exhaust valve attached to the cylinder head to the crankshaft, and the rocker arm pushes down the intake valve and the exhaust valve. I am trying to open it. The rocker arm is rotatably supported on the rocker shaft, and the side surface of the rocker arm is pressed against the end surface of a cam cap or the like through which the rocker shaft is passed with a spring to regulate the thrust direction and position in the thrust direction. I am trying to do it.

[0003]

The entire side surface of the cylindrical portion of the rocker arm axially supported by the rocker shaft is pressed against the end surface of the cam cap, and the contact area between the rocker arm and the end surface of the cam cap is large. There is a large frictional resistance when the rocker arm swings, resulting in output loss.

In view of the above point, the present invention reduces the contact area of the cam cap which receives the thrust on the side surface of the rocker arm, thereby reducing the frictional resistance during rocking of the rocker arm and reducing the output loss. The purpose of the present invention is to obtain a valve operating system for a four-cycle engine.

[0005]

In order to achieve the above object, a valve operating system for a four-cycle engine according to the present invention comprises a rocker shaft pivotally supported on an end surface of a cam cap through which a rocker shaft mounted on a cylinder head is inserted. The rocker arm is pressed against the side surface of the rocker arm to restrict the thrust of the rocker arm, and a radial notch is provided on the end surface of the cam cap to reduce the contact area between the rocker arm and the cam cap.

[0006]

In the rocker arm, one end of the rocker arm is pushed up by the cam of the cam cap interlocked with the crankshaft to swing, and the intake valve and the exhaust valve are pushed down at the tip to open. The cam cap has a notch in the radial direction on the end face against which the side of the rocker arm is pressed, so the frictional resistance when the rocker arm swings can be reduced by the radial area of the notch. Can reduce the mechanical loss. Further, the notch on the end surface of the cam cap serves as a reservoir of lubricating oil, which improves lubrication.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. The outboard motor 1 is equipped with a four-cycle engine in an upper engine room 2 with its crankshaft placed vertically. A cam cap 3 is provided on the cylinder head of the engine, and the rocker shaft 4 is inserted into and attached to the cam cap 3. A rocker arm 5 is pivotally supported by the rocker shaft 4, and the rocker arm 5 is pressed against the end surface of the cam cap 3 by a spring 6 to regulate thrust. The rocker arm 5 is pushed up and rocked by the cam 8 of the cam shaft 7 which is interlocked with the crankshaft, and the intake valve 9 and the exhaust valve 10 are pushed down by the rocker arm 5 to open. An ignition plug cylinder 11 is provided between the left and right exhaust valves 10.

The cam 8 of the cam shaft 7 which is interlocked with the engine pushes up and rocks the rocker arm 5 by rotation, and pushes down the intake valve 9 and the exhaust valve 10 at the tip to open them.
The side surface of the rocker arm 5 is pressed against the end surface of the cam cap 3 by the spring 6 or the wave washer 15,
Friction is generated when the rocker arm 5 swings. The notch 12 on the end surface of the cam cap 3 is provided on the rocker arm 5
The contact area between the cam cap 3 and the cam cap 3 is reduced to reduce frictional resistance and reduce mechanical loss. Further, the notch 12 of the cam cap 3 serves as a reservoir of lubricating oil, and the rocker arm 5
Improve lubrication.

[0009]

As described above, since the present invention is configured as described above, the friction area between the rocker arm 5 and the cam cap 3 can be reduced by the notch 12 in the cam cap 3, and the rocker arm 5 can be swayed. The frictional resistance due to the movement can be reduced to reduce the mechanical loss, and the output loss of the engine can be reduced. Further, the notch 12 of the cam cap 3 serves as a reservoir of lubricating oil, so that the lubricity of the rocker arm 5 can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of the present invention.

FIG. 3 is an enlarged end view of the cam cap showing the embodiment of the present invention.

FIG. 4 is an end view of the cam cap showing three types of modified examples (a), (b), and (c) of the notch on the end surface of the cam cap of the present invention.

FIG. 5 is an overall side view showing an outboard motor equipped with a four-cycle engine.

[Explanation of symbols]

 3 Cam Cap 4 Rocker Shaft 5 Rocker Arm 12 Notch

Claims (1)

[Claims] Claim: What is claimed is: 1. A rocker arm axially supported by a rocker shaft is pressed against an end surface of a cam cap that is inserted through a rocker shaft mounted on a cylinder head to restrict thrust of the rocker arm. A valve operating system for a four-cycle engine, characterized in that a radial notch is provided on the inner surface of the rocker arm to reduce the contact area between the cam cap and the rocker arm.