JPH0512604U - Camsyaft - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] To provide a camshaft of an internal combustion engine capable of reducing the weight while maintaining necessary strength. A camshaft 1 rotatably supported by a plurality of cam journals 2 and 3 and having a plurality of cams 4 and 5 attached thereto. The camshaft 1 has a cross-sectional shape that is orthogonal to the axis and is shaped to change along the axial direction so that the cross-sectional area on the cams 4, 5 side is maximized.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a camshaft of an internal combustion engine.

[0002]

[Problems to be solved by conventional techniques and devices]

 Conventionally, a cam shaft rotatably supported by a plurality of cam journals and having a plurality of cams attached thereto is formed so that the cross-sectional area in a cross section orthogonal to the axis is constant along the axial direction. By the way, in such a camshaft, each cam attached to the shaft individually drives each rocker arm of the engine. For this reason, the plurality of cams attached to the camshaft generally receive reaction forces from the rocker arms at different timings.

Therefore, the camshaft is not stressed uniformly along the length direction, and it is not always necessary to form the cross-sectional area constant along the axial direction. On the other hand, if the camshaft is molded in the lengthwise direction, the material of the shaft is wasted in the portion that is not stressed, and the weight of the camshaft unnecessarily increases. It was

The present invention has been made in view of the above points, and an object of the present invention is to provide a camshaft capable of reducing the weight while maintaining necessary strength.

[0005]

[Means for Solving the Problems]

 According to the present invention, in order to achieve the above object, in a camshaft rotatably supported by a plurality of cam journals and having a plurality of cams attached, a cross-sectional shape orthogonal to the axis of the camshaft is cut on the cam side. It is shaped into a shape that changes along the axial direction so that the area is maximized.

[0006]

[Action]

 Since the camshaft has the largest cross-sectional area on the cam side and receives the stress acting on the cam side, the cross-sectional area of the cam journal side or the part far from the cam may be smaller than that on the cam side.

[0007]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. FIG. 1 shows a first embodiment of a camshaft according to the present invention. The camshaft 1 has cams 4 and 5 mounted between cam journals 2 and 3 which rotatably support the camshaft 1. The cross-sectional shape of the cams 4 and 5 orthogonal to the axis of the camshaft 1 is shaped to change along the axial direction so that the cross-sectional area on the cams 4 and 5 side is maximized.

When the camshaft 1 is molded into such a shape, for example, when the response W _A acts on one cam 4, the bending moment M applied between the cams 4 and 5 of the camshaft 1 is as shown in FIG. As shown in, when the distance between the cam journals 2 and 3 is L ₀ , the distance between the cam journal 2 and the cam 4 is L _1A, and the distance between the cam journal 2 and the cam 5 is L _1B , the following is obtained. Become. That is, as shown in FIG. 2, the bending moment M takes a maximum value M _MAX = (L _1A × L _1B ) / L ₀ · W _A at the position of the cam 4 and decreases as the distance from the cam 4 increases, The distribution characteristic is zero at the positions of the cam journals 2 and 3.

As shown in FIG. 2, when the distance between the cam journal 3 and the cam 4 is L _2A and the distance between the cam journal 3 and the cam 5 is L _2B , as shown in FIG. The same applies to the bending moment M _B when the stress W _B acts on the other cam 5, and the maximum value M _MAX = (L _2A × L _2B ) / L ₀ · W _B is obtained at the position of the cam 5. The distribution characteristic is zero at the positions of cam journals 2 and 3.

By the way, since not only the bending moment M but also the shearing force and the torsional force act on the camshaft 1, it is difficult to form the camshaft 1 into a shape having uniform strength against all stresses. However, from the above, when the bending moment M is taken into consideration, when the stresses W _A and W _B act on the cams 4 and 5 of the camshaft 1 alternately at different timings, the camshaft 1 is When the shape between the five is molded as shown in FIG. 1, the weight can be reduced without lowering the strength.

Further, FIGS. 4 and 5 show another modification in which the cross-sectional shape orthogonal to the axis of the cam shaft 1 between the cams 4 and 5 is formed into a shape that changes along the axial direction. FIG. 4 shows that the camshaft 1 has the largest cross-sectional area in the portions adjacent to the cams 4 and 5, and has a larger diameter than the diameter between the cam journals 2 and 4 and the cam journals 3 and 5 which are adjacent to each other. This is the case when molded. On the other hand, the cam shaft 1 shown in FIG. 5 is a modified example in which the portion having the smallest diameter with the smallest cross-sectional area between the cams 4 and 5 is biased from the center to the cam 4 side.

Next, a second embodiment of the present invention in which the cross-sectional shape of the cam shaft between the cam journal and the cam is changed along the axial direction will be described with reference to FIG. In this embodiment, the cam shaft 10 is formed between the cam 11 and the cam journals 12 and 13 so that the diameter on the cam 11 side is larger than that on the cam journals 12 and 13 side. Here, the shapes of the conventional camshaft and cam journal are represented by the two-dot chain line in the figure, and the same applies to the modified examples described below.

In the camshaft 10 having such a shape, when stress is applied to the cam 11, the distribution characteristic of the bending moment M becomes maximum at the position of the cam 11, as shown in FIG. Will be zero. As described above, the bending moment M is smaller as it is closer to the cam journals 12 and 13 side. , Can be varied along the axial direction.

Therefore, as shown in FIG. 6, the camshaft 10 can be reduced in weight while maintaining strength, and the cam journals 12 and 13 can also be downsized, so that the weight of one layer can be reduced. It will be possible. Further, as another modification of this embodiment, for example, when the cam 11 is biased to the cam journal 12 side, it is molded like the cam shaft 10 shown in FIG. 8 or shown in FIG. As described above, the portion between the cam 11 and the cam journal 13 may be partially formed in the same cross-sectional area along the axial direction as in the conventional case.

Further, as described above, in the camshaft of the present invention, as in the camshaft 30 shown in FIG. 10, with respect to the cam journals 31, 32 and the cams 33, 34, the cross-sectional areas on the cam 33 side and the cam 34 side are different. The shape may be changed along the axial direction so as to maximize.

[0016]

[Effect of the device]

 As is clear from the above description, according to the camshaft of the present invention, it is possible to effectively reduce the weight while maintaining the required strength, and the industrial utility value is great.

[Brief description of drawings]

FIG. 1 is a front view showing the shape of a camshaft according to a first embodiment of the present invention.

FIG. 2 is a distribution characteristic diagram showing a distribution characteristic of a bending moment when stress acts on one cam in the camshaft of FIG.

FIG. 3 is a distribution characteristic diagram showing a distribution characteristic of a bending moment when stress acts on the other cam in the cam shaft of FIG.

FIG. 4 is a front view of a camshaft showing another modification of the first embodiment.

FIG. 5 is a front view of a camshaft showing still another modification of the first embodiment.

FIG. 6 is a front view showing the shape of a camshaft according to a second embodiment of the present invention.

7 is a distribution characteristic diagram showing distribution characteristics of bending moment when stress is applied to the cam in the cam shaft of FIG.

FIG. 8 is a front view of a camshaft showing another modification of the second embodiment.

FIG. 9 is a front view of a camshaft showing still another modification of the second embodiment.

FIG. 10 is a front view showing still another modified example of the camshaft of the present invention.

[Explanation of symbols]

 1 camshaft 2,3 cam journal 4,5 cam 10 camshaft 11 cam 12,13 cam journal 30 camshaft 31,32 cam journal 33,34 cam

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Nagano 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (1)

[Scope of utility model registration request] 1. A camshaft, which is rotatably supported by a plurality of cam journals and has a plurality of cams attached thereto, has a cross-sectional shape orthogonal to the axis of the camshaft so that the cross-sectional area on the cam side becomes maximum. , A camshaft formed into a shape that changes along the axial direction.