JPH0893415A - Built-up type camshaft for internal combustion engine - Google Patents

Abstract

PURPOSE: To lower the manufacturing cost by lessening the number of installation members for a built-up type camshaft. CONSTITUTION: Regarding a built-up type camshaft in which a rising part 11 is formed in the outer circumference of a metal pipe 1 and a cam piece 2 is installed; said cam piece is composed of an inner piece 21 having a circular hole having a slightly smaller inner diameter part than the outer diameter of the rising part 11 and an outer piece 22 to be joined in the outside of the inner piece 21: the inner piece 21 is extended in the axial direction and furthermore a flange part is formed at the tip of the inner piece to compose a projected-type thrust piece 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft called a prefabricated type camshaft used in an internal combustion engine such as a gasoline engine or a diesel engine.

[0002]

2. Description of the Related Art As is well known, in an internal combustion engine such as a gasoline engine or a diesel engine, a cam attached to a cam shaft which works with a main shaft (crank shaft) of the engine is used to supply or exhaust air to each cylinder. It controls the timing. An example of the camshaft is shown in FIG.

FIG. 5 shows a camshaft of a 6-cylinder engine.
A gear attached to one end rotates in conjunction with the main shaft of the engine. 1 is a metal tube, 2 is a cam piece corresponding to each cylinder a to f of the engine, 3 is a journal piece that supports rotation of the cam shaft, 4 is a thrust piece that supports axial positioning and thrust of the cam shaft, and 5 is a thrust piece. The oil seal piece 6 is an end piece that closes the end of the pipe, and 2 to 6 are hereinafter referred to as attachment members for the metal pipe 1.

Conventionally, the camshaft has been integrally manufactured by forging or casting, and the shaft portion has a solid structure.
Along with the reduction in weight and speed of engines, "assembled camshafts" having a structure in which cams and other members are attached to hollow metal pipes have been developed and are in widespread use. As an example thereof, a method of attaching a member to a metal tube disclosed in Japanese Patent Laid-Open No. 5-10340 will be described with reference to FIGS.

FIG. 6 is a front view showing an example of the material of the shaft.
A circumferential or spiral ridge 11 is formed at a predetermined location of the metal tube 1 by bulging with a knurl (a tool that presses a cylindrical work with a lathe or the like to make unevenness).
On the other hand, FIG. 7 is a side view of a cam piece 2 which is an example of a member attached to the metal tube 1. The mounting holes provided in the cam piece 2 have several points on the arc surface 2a on the chord surface.
2b, the diameter of the arc surface 2a is larger than that of the raised portion 11 of the metal tube 1, and the interplanar distance of the chord surface 2b is smaller than the outer diameter of the raised portion 11, but the metal tube 1 Is larger than the outer diameter of the general part of. Therefore, when the cam piece 2 is press-fitted to the position of the raised portion 11 of the metal tube 1, one or both of the chordal surface 2b and the raised portion 11 is plastically deformed and is fitted in a predetermined position. The state after press fitting is shown in FIG.

A member such as a cam piece attached to the metal pipe 1 has an outer portion in a follower-to-point contact in the case of a cam, and a bearing or a sliding contact in the case of a journal, so that mechanical strength and wear resistance. In addition, it is preferable that the inner portion to be attached to the shaft is made of a soft material that is easily plastically deformed, because press-fitting is easy and there is no risk of cracking, while accuracy of the finished dimensions is required. Therefore, Japanese Patent Application Laid-Open No. 5-60203 discloses a structure in which the outer portion and the inner portion are made of different members made of different materials. This is shown in FIGS.

FIG. 9 is a side view showing an example of a cam piece in which the outer portion and the inner portion are made of different members made of different materials. The cam piece 2 is an inner inner piece fitted to a shaft.
21 and the outer outer piece that defines the cam profile
Composed of 22 and. The inner piece 21 is made of low carbon steel, and the outer piece 22 is made of a sintered alloy. Both are heated to a temperature not lower than the recrystallization temperature and not higher than the melting point in a sintering furnace and integrated by diffusion bonding. This diffusion bonding is highly reliable because the difference in carbon concentration between the two is large, and the axial hole portion of the inner piece 21 is not deformed by sintering. In addition to the diffusion bonding, brazing or welding may be used. Metal tube 1
If the raised portion 11 is harder than the low carbon steel of the inner piece 21, it is less likely to be cut during fitting, and the strength of the metal tube 1 is not reduced. The mated state is shown in FIG.

On the other hand, the thrust piece 4 has various types and mounting positions depending on the engine design. The format is roughly divided into two types.
Each of them is described in Japanese Patent Publication No. 15, which will be described with reference to them. As shown in FIG. 11, the thrust piece 4 attached to the metal tube 1 has a single flange shape,
This is supported from both sides by the thrust receiving portions 7a and 7b on the casing side. 3 is a journal piece. Hereinafter, this type is referred to as a convex thrust piece.

Further, in the structure shown in FIG. 12, the thrust piece 4 attached to the metal pipe 1 has a double flange shape, and the thrust receiving portion 7 on the casing side is engaged in the middle thereof to support the thrust. There is. This type is called a concave thrust piece. Further, since the thrust piece 4 may be attached at any one position in the entire length of the camshaft, it is often provided at the shaft end portion, but it may be provided at the intermediate portion.

[0010]

By the way, such an assembly type camshaft is one in which a large number of cam pieces and other mounting members are fitted to a metal tube having a uniform outer diameter. The outer diameter of the raised portion 11 formed by is almost uniform. Therefore, when assembling the camshaft, it is not possible to perform knurling at multiple points in advance at one time.Each time one member is assembled, knurling at the next point is performed, and the members are fitted one by one from the shaft end. It takes time and effort because it has to be done. Therefore, it has been desired to reduce the number of members without changing the structure of the camshaft.

An object of the present invention is to realize a camshaft in which the number of members is reduced by combining a part of the members and the assembling work is made efficient.

[0012]

According to the present invention as set forth in claim 1, a raised portion is formed on the outer peripheral surface of a metal tube, and a circular hole having an inner diameter portion slightly smaller than the outer diameter of the raised portion is provided. In a prefabricated camshaft of an internal combustion engine, wherein a mounting member is mounted by press-fitting the circular hole into a raised portion of the metal pipe, one point of the mounting member is extended in an axial direction, and a tip is radially extended. An assembled camshaft for an internal combustion engine, characterized in that a flaring flange portion is formed to form a convex thrust piece.

According to a second aspect of the present invention, a mounting member having a circular hole having a raised portion formed on an outer peripheral surface of a metal tube and having an inner diameter portion slightly smaller than an outer diameter of the raised portion is provided. In a prefabricated camshaft for an internal combustion engine, in which holes are press-fitted and attached to the raised portion of the metal pipe, two points of the attachment member are extended in the axial direction, and a flange portion that expands in the radial direction is formed at the tip thereof. An assembling type camshaft for an internal combustion engine, characterized in that the two mounting members are mounted side by side with the flanges inside to form a concave thrust piece.

A third aspect of the present invention is the assembled camshaft for an internal combustion engine according to the first or second aspect, wherein the mounting member extending in the axial direction is low carbon steel. According to a fourth aspect of the present invention, an annular inner member having a circular hole having a raised portion formed on the outer peripheral surface of a metal tube and having an inner diameter portion slightly smaller than the outer diameter of the raised portion, and the inner member. In a prefabricated camshaft for an internal combustion engine, in which a mounting member made of an outer member joined to the outer side of the inner member is press-fitted into a raised portion of the metal pipe to mount the mounting member, An assembled camshaft for an internal combustion engine, characterized in that only the inner member is extended in the axial direction, and a flange portion extending in the radial direction is formed at the tip of the inner member to form a convex thrust piece.

According to a fifth aspect of the present invention, a ridge is formed on the outer peripheral surface of the metal tube, and an annular inner member having a circular hole having an inner diameter portion slightly smaller than the outer diameter of the ridge, In a prefabricated camshaft for an internal combustion engine, wherein a mounting member made of an outer member joined to the outside of the inner member is mounted by press-fitting a circular hole of the inner member into a raised portion of the metal pipe, Only the two inner members are extended in the axial direction, and further, a flange portion that expands in the radial direction is formed at the tip thereof, and the two-point mounting members are mounted side by side with the flange portions facing inward to form a concave thrust piece. An assembled camshaft for an internal combustion engine, which is characterized in that

The present invention according to claim 6 is the assembled camshaft for an internal combustion engine according to claim 4 or 5, wherein the inner member is low carbon steel, and the invention according to claim 7 is a flange. The assembled camshaft for an internal combustion engine according to claim 3 or 6, wherein the surface of the portion is quenched.

[0017]

According to the present invention, in the assembled camshaft of an internal combustion engine, of the mounting members such as the cam piece, journal piece, and end piece mounted on the metal pipe, the inner diameter portion of the mounting member adjacent to the thrust piece is extended. Then, by providing a flange at the tip and using this as a thrust piece, it is possible to eliminate a single thrust piece and reduce the number of members.

[0018]

【Example】

Example 1 A first example of the present invention is shown in FIG. This is a cross-sectional view showing a part of a camshaft, 1 is a metal tube, 11 is a raised part, 2 is a cam piece, 21 is an inner piece, 22 is an outer piece, and 4 is a convex thrust piece. is there. The cam piece 2 and the thrust piece 4, which were originally two separate members, are made of low carbon steel of the same material as the inner piece 21 and the thrust piece 4 of the cam piece 2, and are integrally molded to form L.
By using a member having a V-shaped cross section, it is possible to reduce the number of members by one point, and further, since the thrust piece 4 has an increased length of the mounting portion as compared with the case where it is mounted alone, the mounting strength is also improved. .

Embodiment 2 A second embodiment of the present invention is shown in FIG. This figure is a cross-sectional view showing a part of a camshaft, 1 is a metal tube, 11 is a raised portion, 2 is a cam piece, 21 is an inner piece, 22 is an outer piece, and 4 is a concave formed by a pair. It is a shaped thrust piece. Cam piece 2 which was originally a separate member
And thrust piece 4 as inner piece of cam piece 2.
21 and the thrust piece 4 are made of the same material of low carbon steel and are integrally molded into a member having an L-shaped cross section, the number of members can be reduced by 2 points, and the joining strength of the thrust piece 4 is also improved.

Third Embodiment A third embodiment of the present invention is shown in FIG. This figure is a cross-sectional view showing the end of the camshaft, where 1 is a metal pipe, 6 is an end piece attached to the shaft end, and the convex thrust piece 4 and end piece 6 are integrated as low carbon steel of the same material. It is possible to reduce the number of members by one and to improve the joint strength of the thrust piece 4. As described above, not only the end piece but also the thrust piece is integrally molded with the adjoining one-point attachment member when the thrust piece is convex, and when the thrust piece is concave, the thrust piece is formed at two points on both sides adjacent to each other. By molding integrally with the mounting member, the present invention can be implemented in various modes depending on the engine design.

Embodiment 4 A fourth embodiment of the present invention is shown in FIG. This figure is a sectional view showing a part of the camshaft as in FIG. 1, and 1 is a metal tube,
2 is a cam piece, 21 is an inner piece, 22 is an outer piece, and 4 is a thrust piece. Then, the inner piece 21 of the cam piece 2 and the thrust piece 4 were made of the same material of low carbon steel, and the flange portion surface 41 which was the sliding surface of the thrust piece 4 was quenched and then press-fitted into the metal tube 1. Since it is not preferable during press-fitting that the inner piece side becomes hard due to the quenching effect on the inner diameter portion, it is necessary to provide the chamfered portion 42 as shown in (a) or the inner diameter processed portion 43 as shown in (b). Inner piece 21
It is desirable to leave the corners of.

Since the quenching process is carried out at the parts stage, a large furnace for accommodating the entire length of the camshaft is not necessary, and the press-fitted portion such as the attached cam piece is not loosened or deformed.

[0023]

According to the present invention, in an assembled camshaft for an internal combustion engine, since it is possible to reduce the number of attached parts by eliminating a single thrust piece, it is possible to reduce the assembling time and man-hours, and further to reduce the thrust. It has an excellent effect that the attachment strength of the piece is improved and the service life is extended.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a front view showing an example of a camshaft according to the present invention.

FIG. 6 is a front view of a part of a camshaft showing a conventional technique.

FIG. 7 is a side view of a cam piece showing a conventional technique.

8 is a front view showing a state where the cam piece of FIG. 7 is press-fitted into a cam shaft.

FIG. 9 is a side view of a cam piece showing another conventional technique.

10 is a front view showing a state where the cam piece of FIG. 9 is press-fitted into a cam shaft.

FIG. 11 is an assembled sectional view around a thrust piece showing a conventional technique.

FIG. 12 is an assembled sectional view around a thrust piece showing another conventional technique.

[Explanation of symbols]

 1 metal tube 2 cam piece (mounting member) 3 journal piece (mounting member) 4 thrust piece (mounting member) 5 oil seal piece (mounting member) 6 end piece (mounting member) 7, 7a, 7b thrust receiving portion 11 raised portion 21 Inner piece 22 Outer piece 41 Flange surface 42 Chamfer processing 43 Inner diameter processing

Claims (7)

[Claims] 1. A mounting member (2) having a circular hole having a raised portion (11) formed on the outer peripheral surface of a metal pipe (1) and having an inner diameter portion slightly smaller than the outer diameter of the raised portion (11). 6)
In a prefabricated camshaft of an internal combustion engine in which the circular hole is press-fitted and mounted in a raised portion (11) of the metal pipe (1), one point of the mounting member (2-6) is extended in an axial direction, Furthermore, a prefabricated thrust piece (4) is formed by forming a flange portion that expands in the radial direction at the tip thereof, and is an assembly type camshaft for an internal combustion engine. 2. A mounting member (2) having a circular hole having a raised portion (11) formed on the outer peripheral surface of a metal tube (1) and having an inner diameter portion slightly smaller than the outer diameter of the raised portion (11). 6)
In a prefabricated camshaft of an internal combustion engine in which the circular hole is press-fitted and mounted in a raised portion (11) of the metal pipe (1), two points of the mounting member (2 to 6) are extended in an axial direction, Further, a flange portion that expands in the radial direction is formed at the tip thereof, and the two thrust members are mounted side by side with the flanges inside to form a concave thrust piece (4). Camshaft. 3. A mounting member (2 to 2) extending in the axial direction.
The assembly type camshaft for an internal combustion engine according to claim 1 or 2, wherein 6) is low carbon steel. 4. A ring-shaped inner member having a circular hole having a raised portion (11) formed on the outer peripheral surface of a metal pipe (1) and having an inner diameter portion slightly smaller than the outer diameter of the raised portion (11). 21) and an attachment member (2-6) consisting of an outer member (22) joined to the outside of the inner member (21), the inner member (21)
In a prefabricated camshaft for an internal combustion engine, in which the circular hole is press-fitted and attached to the raised portion (11) of the metal pipe, only one inner member (21) of the attachment members (2 to 6) is axially arranged. And a flange portion that extends in the radial direction at the tip thereof to form a convex thrust piece (4). 5. An annular inner member (1) having a circular hole having a raised portion (11) formed on the outer peripheral surface of the metal pipe (1) and having an inner diameter portion slightly smaller than the outer diameter of the raised portion (11). 21) and an attachment member (2-6) consisting of an outer member (22) joined to the outside of the inner member (21), the inner member (21)
In a prefabricated camshaft of an internal combustion engine in which the circular holes of are attached by press-fitting to the raised portions (11) of the metal pipe (1), only the two inner members (21) of the attachment members are axially extended. Further, a flange portion that expands in the radial direction is further formed at its tip, and the two-point mounting members are mounted side by side with the flange portion facing inward to form a concave thrust piece (4). Assembly type camshaft of engine. 6. The assembled camshaft for an internal combustion engine according to claim 4, wherein the inner member (21) extending in the axial direction is made of low carbon steel. 7. The assembled camshaft for an internal combustion engine according to claim 3, wherein the surface of the flange portion (41) is quenched.