JPH04105902U - camshaft - Google Patents

Abstract

(57) [Summary] [Purpose] The camshaft is made into a pipe-like structure, and the weight is reduced while maintaining the strength of the camshaft. [Structure] A camshaft 8 is constructed by fitting a cam sprocket journal 1 to the left end of a camshaft main body 5 having a cam 4 and a journal 3 fitted to its outer peripheral surface. A cam sprocket 6 is attached to the cam sprocket journal 1 with a mounting bolt 7. When the cam sprocket 6 is rotated by a belt (not shown) wrapped around the cam sprocket 6, the camshaft 8 rotates together with the cam sprocket 6. At this time, since the cam sprocket journal 1 is made of cast iron,
The axial force of the mounting bolt 7 is improved.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a camshaft that reduces engine weight and improves vehicle performance. Regarding.

0002

[Conventional technology]

Traditionally, automobile engines have been equipped with valves for supply and exhaust and for opening and closing these valves. One is known that is provided with a second cam. This cam is fixed to the camshaft As the cam rotates with the rotation of the camshaft, the valve for supply and exhaust It has a structure that opens and closes.

0003 Therefore, the camshaft resists torsional torque etc. to open and close the valve via the cam. Conventionally, an integrally formed solid shaft made of cast iron was used. It was common to be

0004

[Problem that the idea aims to solve]

As mentioned above, torsional rigidity, torsional strength (torsional breaking torque, torsional fatigue strength, etc.), etc. From the point of view, the camshaft is composed of a solid shaft, but in recent years the lightweight of the engine There is a growing demand for greater diversity and eloquence.

[0005] Therefore, we aim to reduce the weight and improve the performance of the camshaft as a component of the engine. Therefore, it has been considered to form the camshaft with a hollow pipe-shaped shaft. deer However, when a pipe-shaped camshaft is used, the material used for the camshaft changes from the conventional cast iron to the structure. It was necessary to change to carbon steel, etc. from the viewpoint of design and shape. For this reason, Kamsha The cam sprocket that transmits power to the foot is the attachment part to the camshaft. The Mus sprocket journal was also made of carbon steel.

[0006] As a result, the cam sprocket can be attached to the camshaft by screwing the mounting bolt. When installing the bolts, the problem arises that the axial tension of the mounting bolts decreases. Ta.

[0007] Based on the above, it is possible to reduce the weight of the camshaft while also supporting the cam sprocket journal. There is a need to improve the axial force of mounting bolts.

[0008]

[Means to solve the problem]

The camshaft according to the present invention is a pipe-shaped camshaft in which a cam is fitted on the outer circumferential surface. A cam sprocket is screwed to the end of the main body, and A cam sprocket journal is installed to transmit the rotation of the camshaft to the camshaft body. In the camshaft, the cam sprocket journal is made of cast iron. It is characterized by this.

[0009]

[Effect]

When the cam sprocket is rotated, the cam sprocket is screwed The camshaft body is rotated via the proket journal, causing the cam to rotate. At this time, since the cam sprocket journal is made of cast iron, it cannot be screwed. The axial force at the time is improved.

0010

【Example】

A first embodiment of the camshaft of the present invention is shown in FIG. 1, and this embodiment is based on this figure. Explain.

[0011] As shown in Figure 1, between the cam sprocket journal 1 and the rear journal 2. The camshaft body 5 connects the camshaft body 5, and the camshaft body 5 A plurality of journals 3 are fitted together to prevent deformation and maintain stable rotation. It is placed. Also, on the camshaft body 5, there is also an engine (not shown). A cam 4 for opening and closing the valve is similarly fitted and installed. In other words, by the dice The camshaft body 5 has teeth rolled on its outer periphery, and a journal with teeth formed on its inner surface. 3 and cam 4 are press-fitted and attached at predetermined positions and angles.

0012 Therefore, the cam sprocket journal 1 and rear The journal 2 etc. are press-fitted into the camshaft body 5, and the journal 3 and the camshaft body 5 are press-fitted. The cam 4 is press-fitted, and the camshaft 8 is assembled.

[0013] On the other hand, the pipe-shaped camshaft body 5 is made of carbon steel such as S45C material. However, the cam sprocket journal 1 that constitutes the end of the camshaft 8 is made of cast iron such as FCD70 material. And the cam sprocket jaw A cam sprocket 6, on which a belt (not shown) is wrapped, is attached to a mounting bolt 7 on the nut 1. It is attached by screwing into the cam sprocket journal 1.

[0014] Therefore, the cam sprocket 6 is rotated by the movement of the belt, and accordingly, the cam sprocket 6 is rotated. As the Mus sprocket journal 1 and the camshaft body 5 are rotated, the cam 3 will be rotated.

[0015] In addition, the axial force of the mounting bolt 7 in this embodiment is made of carbon steel such as S45C. A comparison with a case using a cam sprocket journal is shown below.

[0016] In other words, in this example, it is possible to obtain an axial force of 2160 kgf to 2460 kgf. However, in the case of a carbon steel cam sprocket journal, it is 175 The axial force will be between 0kgf and 2240kgf. Therefore, the cam sprocket journal By using cast iron as the material of 1, the tightening bolt 7 can be tightened more easily than carbon steel. The bolt axial force, which is an additional characteristic, will be improved by about 20%.

[0017] The conditions for the above comparison are that the tightening torque of the tightening bolt 7 is 8 kgf. m to 10 kgf・m and apply oil.

On the other hand, the cast iron that forms the cam sprocket journal 1 has a thermal expansion coefficient of 11.8 × 10 ^{-6 (1/k), whereas the carbon steel that forms the camshaft body 5 has a thermal expansion coefficient of 11.8 × 10 -6} (1/k). is 11.3×10 ⁻⁶ (1/k). Therefore, the cam sprocket journal 1, which is press-fitted into the camshaft body 5, has a larger coefficient of thermal expansion than the camshaft body 5, and as the temperature of the engine increases as the engine operates, these members are tightened. The force is even greater, and it also has the effect of preventing loosening.

[0019]

[Effect of the idea]

According to the camshaft of the present invention, the cam sprocket journal is made of cast iron. As a result, the gap between the cam sprocket and the cam sprocket journal The axial force of the tightening bolt that tightens the screw increases, making it possible to ensure sufficient strength. became.

[0020] Therefore, the strength of the camshaft formed with a hollow shaft is improved, and the strength of the camshaft formed with a conventional solid shaft is improved. It is possible to obtain performance equivalent to or better than that of a conventional camshaft.

[0021] From the above, it is possible to reduce the weight of camshafts, change materials, and reduce costs by saving materials. At the same time, it is possible to reduce the weight and cost of the engine. come.

[Brief explanation of drawings]

FIG. 1 is a side partial sectional view showing a camshaft according to an embodiment of the present invention.

[Explanation of symbols]

1 Cam sprocket journal 2 Rear journal 3 Journal 4 cam 5 Camshaft body 6 Cam sprocket 7 Mounting bolt 8 Camshaft

Claims (1)

[Scope of utility model registration request] Claim 1: A cam sprocket is screwed to an end of a pipe-shaped camshaft body into which a cam is fitted on the outer peripheral surface, and a cam sprocket journal is provided that transmits rotation from the cam sprocket to the camshaft body. A camshaft attached to the camshaft, wherein the cam sprocket journal is made of cast iron.