JP3106855B2 - Camshaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft used in an internal combustion engine or the like, and more particularly to a camshaft having a synthetic resin cam gear.

[0002]

2. Description of the Related Art Conventionally, a camshaft having a cam gear made of synthetic resin has a boss portion formed at an appropriate position on a cam shaft having cam members arranged in an outer periphery, and a cam gear made of synthetic resin is attached to the boss portion. I was The shape of the boss portion was substantially rectangular in a section perpendicular to the axis, and the cam gear was attached to the cam shaft against a load applied to the cam gear. Such a camshaft is disclosed in Japanese Utility Model Publication No. Sho 62-31604.

In another conventional camshaft, the shape of the boss is substantially circular in a section perpendicular to the axis, the center of the boss is decentered from the axis of the camshaft, and the cam gear is attached to the camshaft. Some of them were. Such a camshaft is disclosed in Japanese Utility Model Publication No. 2-29203.

[0004]

In the above-described camshaft, the cam gear is covered with the camshaft by making the shape of the boss substantially rectangular or by decentering the center of the boss and the axis of the camshaft. To prevent the cam gear from rotating around the cam shaft. However, such a detent structure has a small portion that receives the load against the load applied to the cam gear and is even in the rotation direction. May easily occur.

Accordingly, the present invention solves the above-mentioned problems,
An object is to provide a highly durable camshaft in which a cam gear and a boss are firmly connected.

[0006]

The configuration of the present invention is as follows.

[0007] In a camshaft in which a boss is formed at an appropriate position on a camshaft having a row of cam pieces arranged on the outer periphery and a synthetic resin cam gear is attached to the boss, the boss is perpendicular to the camshaft rotation direction. And a detent projection having at least one rotating end surface.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a partial sectional plan view of the camshaft 1, and FIG. 2 is a side view of the camshaft 1.

In the drawing, reference numeral 2 denotes a cam shaft formed by casting, and cam pieces 6a and 6b and a boss 3 are arranged in a row on the outer periphery.
Bearing portions 9 and 10 are formed at both ends. The boss portion 3 is formed with a pair of detent protrusions 4 having a rotation end face 5 perpendicular to the camshaft rotation direction in the radial direction. The outer periphery of the boss portion 3 is made of a synthetic resin such as polyacetal resin. The cam gear 7 is attached by injection molding. The rotation end face 5 perpendicular to the camshaft rotation direction is formed on a plane passing through the axis of the camshaft 2. Further, the cam gear 7 has a tooth mold 8a on the outer periphery, and has a circumferential underfill 8b on both axial end surfaces.

Next, the use state of the camshaft 1 will be described. The cam gear 7 meshes with a crank gear (not shown),
The driving force of the crank gear is transmitted to the entire camshaft 1 via the cam gear 7. Then, an intake valve and an exhaust valve (not shown) that come into contact with the cam pieces 6a and 6b are lifted. At this time, since the rotation load of the cam gear 7 is received by the rotation preventing projection 4 having the rotation end face 5 perpendicular to the cam shaft rotation direction, the rotation load can be received by the entire rotation end face 5.

In the above embodiment, the rotation end faces 5 perpendicular to the camshaft rotation direction are formed at both ends in the circumferential direction of the rotation preventing projections 4. However, only one end face that receives more rotational load may be the rotation end face 5. good.

[0013]

As described above, according to the present invention, there is provided a camshaft in which a boss is formed at an appropriate position on a camshaft having cam members arranged in a row on an outer periphery, and a synthetic resin cam gear is attached to the boss. Since the boss portion has the detent protrusion having at least one rotation end face perpendicular to the camshaft rotation direction, the rotation load of the cam gear is reduced by the detent protrusion having the rotation end face perpendicular to the camshaft rotation direction. As a result, a rotational load can be received on the entire rotating end face, a high rotational load can be received, and durability can be improved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional plan view illustrating a camshaft according to an embodiment of the present invention.

FIG. 2 is a side view illustrating a camshaft according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 camshaft 2 camshaft 3 boss 4 detent projection 5 rotating end face 6 a cam piece 6 b cam piece 7 cam gear

Claims (1)

(57) [Claims] 1. A boss portion (3) is formed at an appropriate position on a cam shaft (2) having cam members (6a) and (6b) arranged in a row on an outer periphery, and a cam gear (3) made of synthetic resin is provided on the boss portion (3). 7) The camshaft to which the boss portion (3) is attached, wherein the boss portion (3) has a detent projection (4) having at least one rotation end surface (5) perpendicular to the rotation direction of the camshaft (1). A characteristic camshaft.