JPH089479Y2 - Assembly camshaft - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled camshaft in which a hollow pipe material is used as a camshaft of an internal combustion engine, and a separate cam portion and optionally a journal portion are fixed thereto by utilizing bulging or the like.

[0002]

2. Description of the Related Art As camshafts assembled by this type of bulge processing, there are No. 56-124205 and No. 5
6-966 and the like. Also, there is Japanese Patent Application No. 60-22293 by the same applicant as this case.

[0003]

As in the cam shaft 101 shown in FIG. 9, the hollow shaft 102 shown in FIG. 11 is expanded by bulging to fix the cam piece 106, the journal piece 103, etc. shown in FIG. 12, respectively. Therefore, there is a drawback that a large expansion molding force is required.

In the assembled camshaft 101, the cam piece 106, the journal piece 103 and the like are fixed to the hollow shaft 102 so that they cannot rotate, and the cam piece 106, the journal piece 103 and the like are firmly fixed in the axial direction of the hollow shaft 102. There is a need to. In this respect, the through holes for the cam and journal pieces are
As compared with the curved surface shape described in No. 9-28298, through holes 120 and 122 have polygonal hole portions 121 and 123 as shown in FIG. 12, and polygonal chamfered portions 104 are provided on both sides thereof. , 105, 107, 108 are sufficiently satisfactory in terms of bond strength. However, in the case of such a cam piece 106 or the like, as shown in FIGS. 9 and 10, the expanded and deformed outer peripheral surface of the hollow shaft 102a and the polygonal chamfered portion 10 of the cam piece 106 or the like facing the outer peripheral surface thereof.
Gaps C3, C4, ...

The clearances C3, C4 accommodate foreign matter in the subsequent finishing grinding of the assembled camshaft 101 and the hardening treatment of the surface of the cam piece, and after the engine is installed, the foreign matter is discharged into the lubricating oil to form the surface of the cam piece, etc. It has provided the problem of accelerating wear of the tires.

[0006]

The present invention has the following construction.

A through hole of the cam piece is provided with a polygonal hole portion having a polygonal cross section and a circumferential opening peripheral edge, and is connected to both sides of each inner side surface of the polygonal hole portion, and spreads gently toward the side surface of the cam piece. The chamfer is provided so that the adjacent tongue-shaped chamfers are in contact with each other on the peripheral edge of the opening, and the hollow shaft is expanded along the polygonal hole and each tongue-shaped chamfer.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of an assembled camshaft 1. Reference numeral 2a is a hollow shaft such as a steel pipe, and the shape before expansion is shown in FIG. 6 is a cam piece, which is cast in advance,
As shown in FIG. 3, a desired cam profile is substantially formed by forging or sintering, and a through hole 22 through which the hollow shaft 2 before diameter expansion can be inserted is provided.

In the through hole 22, a polygonal hole portion 23 having a hexagonal cross section and a circumferential opening peripheral edge 2 are formed substantially at the center in the axial direction.
5, 26 are provided, and the tongue-shaped chamfered portions 7, 8 are connected to both sides of each inner side surface 24 of the polygonal hole 23 and spread gently toward the side surface of the cam piece 6. The chamfered portions 7, 8 are provided so as to be in contact with each other on the opening peripheral edges 25, 26.

As shown in FIG. 4, the chamfered portions 7 and 8 of the cam piece 6 are formed in such a dimensional relationship that the polygonal hole portion 23 is inscribed at the substantially maximum inner diameter position. .

The chamfered portions 7 and 8 are not limited to the linear taper shape, but as shown in FIGS.
7b may have a rounded shape such as an arc shape, and may have a dimensional relationship in which the polygonal hole portion 23b is inscribed on the smaller diameter side than the maximum inner diameter position.

Reference numeral 3 is a journal piece, which is the cam pieces 6 and 6b.
It has a through hole 20 similar to. If necessary, the cam piece 6 and the journal piece 3 are subjected to surface treatment such as induction hardening or carburizing.

As a method for connecting the hollow shaft 2 of the assembled camshaft 1 and the cam piece 6, first, the cam piece 6 and the journal piece 3 are fitted to a predetermined position of the hollow shaft 2.

Then, this is set in a split bulge mold (not shown) having a predetermined camshaft-shaped mold surface,
Close the mold. As a result, the pair of chamfered portions 7 and 8 of the cam pieces which are adjacent to each other provide an integrated expanded space in the projection surfaces of the chamfered portions which face each other.

Then, with the mold closed, an emulsion or the like is injected into the hollow shaft 2 and the emulsion is compressed and pressurized. Then, the hollow shaft 2 expands outward, and the through hole 22 of the cam piece 6
It is plastically deformed along the inner peripheral surface, the inner peripheral surface of the through hole 20 of the journal piece 3, and the mold surface of the bulge mold. In particular, as shown in FIG. 1, the pair of facing chamfered portions 7 and 8 have a gentle swelling portion common to the chamfered portions 7 and 8 ...
.. is formed. As shown in FIG. 6, the expanded hollow shaft 2a has a tongue-shaped chamfer 7,
The chamfered portions 7 and 8 facing each other at the position of the maximum inner diameter of 8 do not have a gap between the outer periphery of the hollow shaft 2a and the chamfered portions 7 and 8 for foreign matter to enter.

As a result, the cam pieces and the like are firmly fixed to the hollow shaft. Then, after taking out from the bulge mold, the cam surface and the journal portion are ground and finished, and oil holes and the like are machined to complete the desired camshaft 1.

[0018]

As described above, according to the present invention, the enlarged hollow shaft has substantially the maximum inner diameter of each tongue-shaped chamfer provided in the polygonal hole portion having a polygonal cross section of the cam piece through hole. Since the cam pieces are in close contact with the chamfered portion at a position and no gap is generated between the outer periphery of the hollow shaft and the chamfered portion, each cam piece and the like cannot be rotated and is firmly fixed in the axial direction, In addition, foreign matter does not enter the gap, and the foreign matter is not discharged after the engine is installed to abnormally accelerate the wear of the surface of the cam piece or the like.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional plan view of an assembled camshaft according to an embodiment of the present invention. (Represents a cross-sectional view taken along the line AA of FIG. 6.)

FIG. 2 is a partial sectional plan view showing a hollow shaft used in an assembled camshaft according to an embodiment of the present invention.

FIG. 3 is a partial cross-sectional plan view showing a cam piece used in an assembled camshaft according to an embodiment of the present invention.

FIG. 4 is a side view of the cam piece of FIG.

FIG. 5 is a partial cross-sectional plan view of an assembled camshaft according to an embodiment of the present invention, which is shown at an angle different from that of FIG.

6 is a sectional view taken along line FF of FIG.

FIG. 7 is a side view of a cam piece according to another embodiment of the present invention.

8 is a cross-sectional view taken along the line GG of FIG.

FIG. 9 is a partial cross-sectional plan view of a conventional assembled camshaft.

10 is a sectional view taken along line JJ of FIG.

FIG. 11 is a partial cross-sectional plan view showing a hollow shaft used in a conventional assembled camshaft.

FIG. 12 is a partial cross-sectional plan view showing a cam piece used in a conventional assembled camshaft.

[Explanation of symbols]

 1 Assembled camshaft 2, 2a Hollow shaft 3 Journal piece 6 Cam piece 7, 8 Tongue-shaped chamfer 22 Through hole 24 Inner side surface 25, 26 Opening edge

Claims (1)

[Scope of utility model registration request] 1. A hollow shaft (2) is inserted into a through hole (22) of an annular cam piece (6), and the hollow shaft (2) is expanded by bulging to increase the cam piece (6) and the hollow shaft. In the cam shaft combined with (2), the through hole (2
2) is provided with a polygonal hole portion (23) having a polygonal cross section and circumferential opening peripheral edges (25) and (26), and on both sides of each inner side surface (24) of the polygonal hole portion (23). A tongue-like chamfered portion (7) which is connected and spreads gently toward the side surface of the cam piece,
(8) the adjacent tongue-shaped chamfers (7),
(8) is provided so as to be in contact with the opening peripheral edges (25) and (26), and the hollow shaft (2) is provided with the polygonal hole (23).
And a camshaft having an enlarged diameter along the tongue-shaped chamfers (7) and (8).