JPH07166818A - Divided type assembled hollow cam shaft and its manufacture - Google Patents

Abstract

PURPOSE:To facilitate manufacture of a hollow cam shaft by providing a hollow cam shaft main body composed of two or more of divided shafts, and connecting the shafts at journal positions. CONSTITUTION:A divided builtup hollow cam shaft 1 has a hollow shaft main body 2 composed of four divided shafts 2A, 2B, 2C, 2D, a plurality of cam pieces 3 press-fitted around the steel shaft main body 2 on its outer periphery of an intermediate portion, journals 4 for connecting the divided shafts 2A to 2D, and end members 5, 6 provided on both ends of the steel shaft main body 2. The cam pieces 3 are paired and press-fitted to the divided shafts 2A to 2D to form four cam piece parts 3A. Cam shaft sprokets are arranged on an end journal member 7 or the end member 5. It is thus possible to facilitate manufacture of the divided builtup hollow cham shaft 1 and satisfactorily connect the divided shafts 2A to 2D by means of the journals 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split type assembled hollow cam shaft for an internal combustion engine and a method of manufacturing the split type assembled hollow cam shaft, and more particularly to a split type assembled hollow cam shaft which is easy to produce and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, with the increasing demand for higher output and lighter weight of automobile engines, lightweight camshafts using hollow shafts have been developed to meet these demands. It is being put to practical use in the department. On the other hand, the cam piece attached to the cam shaft is required to be made of a material having excellent wear resistance and sliding characteristics in consideration of sliding contact as a valve mechanism. Bonded gold is being used.

An example of such a conventional assembled hollow camshaft is shown in FIG. The assembled hollow camshaft 101 consists of a steel hollow shaft body 102 and a steel shaft body 10
2 A plurality of cam pieces 103 press-fitted to the middle part of the outer circumference
And a journal 104 and end members 105 and 106 provided at both ends of the steel shaft body 101. This cam piece 103 forms a cam piece portion 103A by combining two pieces. The above-mentioned conventional assembled hollow camshaft 101 is provided with a predetermined phase difference on the shaft body 102 so that the campiece 10
3 and the journal 104 are sequentially press-fitted, and then the end members 105 and 106 are externally fitted.

[0004]

In the prior art described above, the cam piece 103 is press-fitted in the cam piece portion 103A with a predetermined phase difference corresponding to the intake and the outtake, respectively. Cam piece part 10
Even between 3A, the cylinders (not shown) are press-fitted with a predetermined phase difference corresponding to the difference in timing between cylinders (not shown). As described above, since it is necessary to press-fit the cam pieces 103 one by one at different angles, there is a problem that the assembling work of the assembled hollow cam shaft 101 is not efficient. Moreover, since the control of the press-fitting angle is extremely strict, it is extremely difficult to improve work efficiency.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an assembled hollow cam shaft which can be easily manufactured and a manufacturing method thereof.

[0006]

A split type assembled hollow camshaft according to claim 1, wherein the split type assembled hollow camshaft comprises a hollow shaft body and a cam piece and a journal press-fitted into the hollow shaft body. The hollow shaft body is composed of at least two split shafts, and the split shafts are joined at the journal.

In the split type assembled hollow cam shaft according to the second aspect, the split shaft has a concavo-convex portion in the circumferential direction on the joint surface by the journal.

In the split type assembled hollow cam shaft of claim 3, the journal has an axially uneven portion on its inner peripheral surface.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a split type assembled hollow camshaft, wherein cam pieces are press-fitted into the split shafts so that the cam pieces of adjacent split shafts have a predetermined phase difference between the split shafts. The journal is press fitted.

[0010]

In the split type assembled hollow camshaft according to claim 1,
The hollow shaft body is composed of at least two or more split shafts, and the split shafts are joined at the journals, so that the manufacture thereof is easy.

In the split type assembled hollow cam shaft according to the second aspect, since the split shaft has a concavo-convex portion in the circumferential direction on the joining surface by the journal, the joining of the split shaft by the journal is favorable.

In the split type assembled hollow camshaft according to claim 3, since the journal has an uneven portion in the axial direction on the inner peripheral surface, the joining of the split shaft by the journal is more favorable.

In the method of manufacturing a split type assembled hollow cam shaft according to a fourth aspect of the present invention, cam pieces are press-fitted into the split shafts so that the cam pieces of the adjacent split shafts have a predetermined phase difference between the split shafts. Since the journal is press-fitted, the split type assembled hollow camshaft can be easily manufactured.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The split type assembled hollow cam shaft 1 of the present invention includes four split shafts 2A, 2B,
Hollow shaft body 2 composed of 2C and 2D
A plurality of cam pieces 3 press-fitted into the outer peripheral intermediate portion of the steel shaft body 2 and the split shafts 2A.
.. and the end members 5, 6 provided at both ends of the steel shaft main body 1. This cam piece 3 is press-fitted into each of the divided shafts 2A. Thus, four sets of cam piece portions 3A are formed. Reference numeral 7 is an end journal member, and a camshaft sprocket (not shown) is attached to the end member 5.

In the split type assembled hollow cam shaft 1, the hollow shaft main body 2 includes split shafts 2A, 2B,
A split shaft 2A which is a cylindrical tube having 2C and 2D as its constituent units and which constitutes one end of the hollow shaft body 2.
2A, an annular knurl 22A is formed at one end as an uneven portion in the circumferential direction, as shown in FIG. Split shaft 2
B and 2C have the same shape, and as shown in FIG. 2 (b), annular knurls 22A, which are uneven portions in the circumferential direction, are formed at both ends. The split shaft 2D basically has the same shape as the split shaft 2A, but is slightly longer because the end journal member 7 is press-fitted. In the present embodiment, each of the divided shafts 2A ... Has a triangular tooth-shaped concave-convex portion 21 on the inner peripheral surface thereof, and an annular knurl 22B is also formed at the installation location of the cam piece 3. The annular knurl 22A has a shape as shown in FIG. The cam piece 3 is a sintered body, is positioned with a predetermined phase difference corresponding to the crank angle, and is press-fitted into each split shaft 2A. Further, two cam pieces 3 are press-fitted into each of the split shafts 2A ... With a phase difference corresponding to the intake and the outtake to form four sets of cam piece portions 3A. In the present embodiment, as shown in FIG. 4, the cam piece 3 has a triangular tooth-shaped uneven portion 31 formed on the inner peripheral surface thereof in the axial direction, that is, in the direction orthogonal to the annular knurl 22B. Journal 4 is made of steel,
As shown in FIG. 5, a triangular tooth-shaped uneven portion 41 similar to the cam piece 3 is formed on the inner peripheral surface thereof. The end members 5 and 6 are made of non-quenched steel material, and the press-fitting portions (not shown) of the end members 5 and 6 are press-fitted into the split shafts 2A and 2D. The press-fitting portion has an annular knurl (not shown) on the outer peripheral surface.

Next, a method for manufacturing the split type assembled hollow cam shaft of the present invention, which is made up of the above-mentioned components, will be described.

First, a hollow steel shaft having a triangular tooth-shaped uneven portion 21 formed on its inner peripheral surface is manufactured by drawing, and annular knurls 22A and 22B are provided at predetermined positions on the hollow shaft.
To roll. Then, the hollow shaft is cut at a predetermined position to manufacture a split shaft. Subsequently, two cam pieces 3 are press-fitted into each of the divided shafts 2A ... With a phase difference corresponding to the intake and the outtake to manufacture intermediate members 20A, 20B, 20C as shown in FIG. The intermediate member 20D basically has the same shape as the dividing member 20A, and therefore will be omitted. Next, the journal 4 is press-fitted into the one end of the intermediate member 20A by about half, and then the cam piece 3 of the intermediate member 20A and the cam piece 3 of the intermediate member 20B are made to have a predetermined phase difference so that the journal 4 is inserted into the remaining portion of the journal 4. The intermediate member 20B is press-fitted and fixed.
This operation is sequentially repeated for the intermediate members 20C and 20D, and the intermediate members 20A, 20B, 20C and 20D are also repeated.
To produce the hollow shaft body 2, and finally the end members 5 and 6 are press-fitted. In the present embodiment, the split shaft 2A and the split shafts 2B and 2C are slightly different in shape, but the split type assembled hollow cam shaft 1 is configured so that all the split shafts 2A ... Have the same shape. By designing the same, the same split shafts are mass-produced in advance, and the cam pieces 3 are press-fitted into them with a predetermined phase difference to manufacture intermediate members of the same shape,
The split type assembled hollow camshaft 1 can be formed by simply connecting the journals 4 with the journal 4 and finally pressing the end members 5 and 6 together.
Can be manufactured. According to the above method, the manufacture of the split type assembled hollow camshaft 1 can be further simplified, and the manufacturing cost is greatly reduced.

Split type assembled hollow camshaft 1 of the present invention
Includes a hollow shaft main body 2, end members 5 and 6 assembled to the ends of the hollow shaft main body, and a plurality of cam pieces 3 and journals 4 made of a sintered body press-fitted into the hollow shaft main body. The hollow shaft main body 2 includes split shafts 2A, 2B, 2C and 2D, and the split shafts 2A ... Are joined by the journal. In particular, each of the divided shafts 2A, ...
Therefore, the joint strength of each split shaft 2A ... Is good. Further, since the journal 4 has the concave and convex portion 41 in the axial direction on the inner peripheral surface, the joint strength of the divided shafts 2A ... With the journal 4 is extremely large, and there is no possibility that the divided shafts 2A. .

Further, in the present invention, the cam pieces 3 are press-fitted into the split shafts 2A, 2B, 2C and 2D so that the cam pieces of the adjacent split shafts have a predetermined phase difference, and the split shafts are provided between the split shafts. The split type assembled hollow camshaft 1 can be easily manufactured by press fitting the journal. Also,
Since the phase differences of the press-fitting of the cam pieces 3 into the respective split shafts 2A ... Are all the same, the intermediate members 20A ... Can be manufactured in the same process, and the work efficiency can be improved. Furthermore, since the split shafts 2B and 2C are the same member and can be shared,
Its manufacture is extremely easy. Especially the split shaft 2A,
By making 2B, 2C and 2D all have the same shape, the production of the split type assembled hollow camshaft 1 can be further simplified and the production cost is greatly reduced.

The present invention has been described above with reference to the accompanying drawings. However, the present invention is not limited to the above-mentioned embodiment, and for example, if the width of the journal 4 is made slightly larger than usual, each split shaft 2A ... The joint strength between the two can be improved. Further, the end surfaces of the divided shafts 2A ... Abutting against each other have triangular tooth shapes 23 as shown in FIG. 7 (a) and are meshed with each other as shown in FIG. 7 (b). Can be prevented.
Further, the end face portion may be roughened. Knurled 22A
And 22B are not limited to the annular ones as in this embodiment,
What has an uneven part in the circumferential direction may be used. For example, in FIG.
It may have an iris shape as shown in FIG. 2 or a spiral knurl. Further, the sectional shape of the uneven portion 21 on the inner peripheral surface of the split shafts 2A is not limited to the triangular tooth shape, and may be a substantially petal shape as shown in FIG. 9 or a shape having various other uneven portions. be able to. Further, the shape of the concave-convex portion 41 on the inner peripheral surfaces of the cam piece 3 and the journal 4 does not have to be a triangular tooth shape, and may be a substantially petal shape, or the corners may be rounded as shown in FIG. It may be a polygonal shape such as a substantially hexagonal shape. Further so-called DOHC
In the case of an engine, the phase difference of the cam piece 3 within the cam piece portion 3A is not necessary.

[0021]

According to the split type assembled hollow cam shaft of claim 1, a split type assembled hollow cam shaft is provided with a hollow shaft main body, and a cam piece and a journal press-fitted into the hollow shaft main body. Is composed of at least two split shafts, and the split shafts are joined together at the journals, so that their manufacture is easy.

In the split type assembled hollow cam shaft according to the second aspect, since the split shaft has a concavo-convex portion in the circumferential direction on the joining surface by the journal, the joining of the split shaft by the journal is good.

In the split type assembled hollow camshaft according to the third aspect, since the journal has an uneven portion in the axial direction on the inner peripheral surface, the joining of the split shaft by the journal is more favorable.

Further, in the method for manufacturing the split type assembled hollow cam shaft according to claim 4, the cam pieces are press-fitted into two or more split shafts so that the cam pieces of the adjacent split shafts have a predetermined phase difference. Since the journal is press-fitted between the split shafts, the split mold assembly hollow cam shaft can be easily manufactured.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing a split type assembled hollow camshaft according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a split shaft of the split type assembled hollow cam shaft of the first embodiment.

FIG. 3 is a partial plan view showing an annular knurl (irregular portion in the circumferential direction) of the split shaft of the first embodiment.

FIG. 4 is a perspective view showing a cam piece of the split type assembled hollow cam shaft of the first embodiment.

FIG. 5 is a perspective view showing a journal of the split type assembled hollow cam shaft of the first embodiment.

FIG. 6 is a perspective view showing an intermediate member used for manufacturing the split type assembled hollow cam shaft of the present invention.

FIG. 7 is a partial front view showing another example of the split shaft, (a) showing a state of an end face and (b) showing a joined state.

FIG. 8 is a front view showing another example of the uneven portion in the circumferential direction of the split shaft.

FIG. 9 is a partial perspective view showing still another example of the split shaft.

FIG. 10 is a perspective view showing another example of a journal.

FIG. 11 is an overall perspective view showing a conventional split type assembled hollow camshaft.

[Explanation of symbols]

 1 split type assembly hollow cam shaft 2 hollow shaft main body 2A, 2B, 2C, 2D split shaft 3 cam piece 4 journals 22A, 22B annular knurl (irregular portion in the circumferential direction) 41 triangular tooth-shaped irregular portion (irregular portion in the axial direction)

Claims (4)

[Claims] 1. A split type assembled hollow cam shaft comprising a hollow shaft main body and a cam piece and a journal press-fitted into the hollow shaft main body, wherein the hollow shaft main body is composed of at least two split shafts. A split mold assembly hollow camshaft, wherein split shafts are joined at the journal. 2. The split type assembled hollow camshaft according to claim 1, wherein the split shaft has a concavo-convex portion in a circumferential direction on a joint surface formed by a journal. 3. The split type assembled hollow camshaft according to claim 1 or 2, wherein the journal has an uneven portion in an axial direction on an inner peripheral surface thereof. 4. The method for manufacturing a split type assembled hollow cam shaft according to claim 1, wherein cam pieces are press-fitted into the split shafts, and the cam pieces of adjacent split shafts have a predetermined phase difference. A method for manufacturing a split type assembled hollow cam shaft, characterized in that the journal is press-fitted between the split shafts.