JP2003184994A - Composite camshaft and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve joining force of a shaft body and a cam piece. <P>SOLUTION: The tubular shaft body 10 in which protruded parts 13 are formed on the outer periphery, and the cam piece 20 in which recessed parts 24 are formed on the inner periphery of an axis hole 23, are provided. The protruded parts 13 are forced to mesh into the recessed parts 24 by enlarging and deforming the shaft body 10 by bulge machining in a state that the shaft body 10 is penetrated into the axis hole 23, while the protruded parts 13 and the recessed parts 24 are being fitted. By this, the shaft body 10 and the cam piece 20 are connected integrally rotatably. Since the protruded parts 13 are formed on the outer periphery of the shaft body 10, and the protruded parts 13 are made so as to fit to the recessed parts 24 of the axis hole 23, even if an amount of enlarging and deforming of the shaft body 10 is small; jointing margins of the protruded parts 13 and the recessed parts 24 can be secured widely. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite camshaft in which a cam piece is connected to the outer circumference of a shaft body and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a composite camshaft in which a cam piece is connected to the outer circumference of a shaft body, a tubular shaft body is used, and the shaft body is expanded and deformed by bulge processing so as to be connected to the cam piece. There is one, and as an example of its disclosure,
No. 38796 and Japanese Utility Model Laid-Open No. 7-35706.

In the former publication, the inner circumference of the shaft hole of the cam piece is formed in a polygonal shape, and the shaft body penetrating the shaft hole is expanded and deformed in a polygonal shape so as to be in close contact with the inner circumference of the shaft hole. Have been disclosed. Further, in the latter publication, similar to the former one, a cam piece in which a shaft hole is formed in a substantially polygonal shape, and a shaft main body so that a recess is formed in the inner periphery of the shaft hole and is closely contacted with the recess. The thing which expanded and deformed is disclosed.

[0004]

In the case where the shaft hole of the cam piece is formed in a polygonal shape, the contact surface between the shaft hole and the shaft main body, that is, the connecting surface is polygonal, and each of the surfaces is generally a camshaft. Since the rotation direction is substantially the same as the rotation direction, there is a problem that the coupling force between the inner circumference of the shaft hole and the outer circumference of the shaft body in the rotation direction is weak.

Further, in the latter type in which a recess is formed on the inner periphery of the shaft hole, since the shape of the recess, that is, the contact surface between the shaft hole and the shaft main body is arcuate, the contact surface is the rotation of the camshaft. The direction is almost the same as the direction, and the coupling force in the rotation direction is also weak. As means for increasing the coupling force, a recess such as a square having a surface in a direction substantially orthogonal to the rotation direction is formed on the inner circumference of the shaft hole, and the shaft body is expanded so as to bite into the recess. It may be possible to cause radial deformation. However, in this case, if an attempt is made to deepen the recess to secure a large coupling margin, the amount of deformation of the shaft body and the curvature of bending will increase, which causes problems such as stress concentration on the shaft body. It is difficult to serve.

The present invention has been made in view of the above circumstances, and an object thereof is to improve the coupling force between the shaft body and the cam piece.

[0007]

The invention of claim 1 comprises a tubular shaft body having a convex portion formed on the outer periphery thereof, and a cam piece having a concave portion formed on the inner periphery of the shaft hole. The shaft by penetrating the shaft main body into the shaft hole through the shaft hole while fitting the recess and the recess, and by bulging the shaft main body to expand and deform the shaft main body into the recess. The main body and the cam piece are integrally rotatably connected.

According to a second aspect of the invention, in the first aspect of the invention, the convex portion and the concave portion have a trapezoidal shape in which the width becomes narrower toward the radially outer side. According to a third aspect of the present invention, in the first or second aspect of the present invention, the axially opposite end surfaces of the cam piece are formed with a pair of cutouts that open into the axial holes of the cam piece, and bulge processing is performed. By making the outer peripheral portion of the shaft body bite into the cutout portion, the cam piece and the shaft body are coupled in the axial direction.

According to a fourth aspect of the invention, in the invention of the third aspect, the innermost end surface in the axial direction of the inner surface of the cutout portion is
An acute angle is formed with respect to the inner peripheral surface of the shaft hole. According to a fifth aspect of the present invention, a convex portion is formed on the outer periphery of the tubular shaft body, and a concave portion is formed on the inner periphery of the shaft hole of the cam piece. Then, the convex portion and the concave portion are fitted to each other. While the shaft body is penetrated through the shaft hole, the shaft body and the cam piece can be integrally rotated by expanding and deforming the shaft body by bulge processing and causing the convex portion to bite into the concave portion. It is configured to be combined with.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the axially opposite end surfaces of the cam piece are formed with a pair of cutouts that open into the axial holes of the cam piece. Then, the cam piece and the shaft body are coupled in the axial direction by biting the outer peripheral portion of the shaft body into the cutout portion by bulging.

[0011]

[Advantageous Effects and Effects of the Invention] [Inventions of Claims 1 and 5] Since the projection is formed on the outer periphery of the shaft body and the projection is fitted into the recess of the shaft hole, the shaft body itself. Even if the amount of diametrical expansion deformation is small, it is possible to secure a large coupling margin between the convex portion and the concave portion. Therefore, the shaft body and the cam piece can be firmly coupled.

[Invention of Claim 2] By bulging, the convex portion fits into the concave portion like a wedge. Therefore, due to the action of the wedge, the shaft body and the cam piece are firmly joined together without rattling. [Invention of Claims 3 and 6] Since the cutout portion and the outer peripheral portion of the shaft body are locked at two positions in the axial direction, a high coupling force can be obtained. [Invention of Claim 4] When an axial force is applied, the acute angle portion bites into the outer peripheral portion of the shaft main body, so there is no fear that the coupling force will decrease.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. The composite camshaft of this embodiment includes a shaft body 10 that rotates in conjunction with an internal combustion period, and a shaft body 1
And a cam piece 20 that is fitted to be rotatable integrally with zero.

First, the shaft body 10 will be described. The shaft main body 10 has a tubular shape as a whole, and the inside of the hollow thereof is a central hole 11 having a circular cross section formed over the entire length of the shaft main body 10. The central hole 11 has a high pressure for bulging. A fluid supply source (not shown) is connected. In addition, the outer peripheral surface of the shaft body 10 that serves as a base is a circumferential surface 12 that is concentric with the central hole 11, and this circumferential surface 12 is parallel to the axial direction over the entire length of the shaft body 10. 4 projections 1 extending to
3 are formed to project at an equal angular pitch of 90 ° in the circumferential direction. The cross-sectional shape (cross-section orthogonal to the axis of the shaft body 10) of the convex portion 13 has a width dimension (circumferential dimension) gradually increasing toward the radially outer side (the protruding direction of the convex portion 13 from the circumferential surface 12). It has a trapezoid shape that narrows.

The cam piece 20 has a substantially oval shape in which a cam nose portion 22 is projected from a base circular portion 21, and the cam piece 20 has a circular shape concentric with the base circular portion 21 and an inner diameter of the outer circumference of the shaft body 10. A shaft hole 23 having a size slightly larger than the outer diameter of the circumferential surface 12 is formed therethrough. On the inner circumference of the shaft hole 23, the shaft body 1
Four concave portions 24 are formed at an equal angular pitch of 90 ° in the circumferential direction so as to correspond to the convex portions 13 of 0. Recess 24
The cross-sectional shape (a cross section orthogonal to the axis of the shaft body 10 and the cam piece 20) has a width dimension (in the circumferential direction) toward the radially outer side (the direction from the inner peripheral surface of the shaft hole 23 toward the back of the recess 24). It has an isosceles trapezoid whose dimensions gradually narrow. The inclination angle of both trapezoidal slopes 24A of the recess 24 is
The angle is set to be approximately the same as the inclination angle of both trapezoidal slopes 13A of the convex portion 13. Further, as compared with the projecting dimension of the convex portion 13 (the radial dimension from the circumferential surface 12 to the projecting end surface 13B of the convex portion 13), the depth dimension of the concave portion 24 (from the inner peripheral surface of the shaft hole 23 to the deep portion of the concave portion 24). The radial dimension up to the end surface 24B) is set larger.

Further, in the cam piece 20, four pairs of notches 25 are formed so as to open in both axial end surfaces of the cam piece 20 and open in the axial hole 23 of the cam piece 20 so as to form a pair in the axial direction. Has been done. This 4
The pair of notches 25 are arranged at an equal angular pitch of 90 ° in the circumferential direction, and each notch 25 and the recess 2 are provided.
4 are arranged so as to be offset from each other by an angle pitch of 45 ° in the circumferential direction. The shape of the notch 25 as viewed in the axial direction is substantially rectangular. Further, of the inner surface of the cutout portion 25, the innermost end surface 25A in the axial direction forms an acute angle with the inner peripheral surface of the shaft hole 23. Although not shown in the drawing, this acute angle portion has a slight curved surface (for example, 0.3 mm).
Arc shape).

Next, the shaft body 10 and the cam piece 20.
The coupling step with and will be described. First, the cam piece 20
While allowing the shaft body 10 to pass through the shaft hole 23 of
The convex portions 13 and the concave portions 24 are loosely fitted (see FIGS. 4 and 8).
See). At this time, as shown in FIG.
There is a slight gap between the inclined surface 13A of the concave portion 24 and the inclined surface 24A of the concave portion 24, and a gap is also formed between the protruding end surface 13B of the convex portion 13 and the rear end surface 24B of the concave portion 24. The shaft body 10 is allowed to expand and deform due to processing.

Next, in the outer periphery of the shaft body 10, the region is exposed from the cam piece 20 and is thinner than the region where the convex portion 13 is not formed, that is, the region where the convex portion 13 is formed, and the diameter is easily expanded and deformed. A deformation restriction jig (not shown) is applied to the area. However, the region corresponding to each notch 25 is kept in non-contact with the deformation restricting jig. When a high-pressure fluid is pressure-fed to the central hole 11 of the shaft body 10 from this state, the shaft body 10 is expanded and deformed. Due to this diameter expansion deformation,
As shown in FIG. 5B, the convex portion 13 is press-fitted into the concave portion 24, and as shown in FIG. It will be in a state of cutting into. In this coupled state, the slopes 13A and 24A of the convex portion 13 and the concave portion 24 abut (adhere) to each other in a direction substantially orthogonal to the rotation direction of the shaft body 10, so that a high coupling force is obtained in the rotation direction. . In the cutout portion 25, the shaft body 1
The outer peripheral portion 10A of 0 bulges and enters the notch 25, so that an axial coupling force is generated between the shaft body 10 and the cam piece 20. As described above, the shaft body 10 and the cam piece 20 are coupled in a state in which the free movement in the circumferential direction and the axial direction is restricted.

As described above, in the composite camshaft and the manufacturing method thereof according to the present embodiment, the convex portion 13 is formed on the outer periphery of the shaft body 10, and the convex portion 13 is formed.
Since it is adapted to be fitted into the recess 24 of the shaft hole 23 of 0,
Even if the amount of diametrical expansion of the shaft body 10 itself in the bulge processing is small, a large coupling margin between the convex portion 13 and the concave portion 24 is secured, and the shaft body 10 and the cam piece 2
It is possible to firmly bond with 0.

Further, since the convex portion 13 and the concave portion 24 have a trapezoidal shape, the convex portion 13 firmly digs into the concave portion 24 like a wedge, and the coupling strength is further enhanced. Further, the outer peripheral portion of the shaft main body 10 that bites into the cutout portion 25 is locked at the two positions so as to be sandwiched from both sides in the axial direction with respect to the cam piece 20, so that a high coupling force is obtained and the cam piece 20 with respect to the shaft main body 10 is provided. Free movement in the axial direction is regulated.

Further, since the innermost surface 25A in the axial direction of the inner surface of the cutout portion 25 makes an acute angle with the inner peripheral surface of the shaft hole 23, when the axial force acts, this acute angle portion is formed. It comes to bite into the outer peripheral portion 10A of the shaft body 10. Therefore, there is no fear that the binding force will decrease. [Other Embodiments] The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. Various modifications can be made without departing from the scope of the invention.

(1) In the above embodiment, the convex portion and the concave portion have a trapezoidal cross section, but according to the present invention, they may have other shapes such as a rectangle, a square, and a triangle. (2) In the above embodiment, four convex portions and four concave portions are provided, but according to the present invention, the number of convex portions and concave portions may be three or less, or may be five or more. (3) In the above embodiment, the axially inner end surface of the cutout portion is formed at an acute angle with respect to the inner circumference of the shaft hole. However, according to the present invention, it may be a right angle or an obtuse angle.

(4) In the above embodiment, the convex portion is provided long along the axial direction of the shaft body, but according to the present invention, the convex portion is formed only at the position corresponding to the concave portion of the cam piece in the axial direction. Good. (5) In the above embodiment, the notch is provided as the means for obtaining the coupling force in the axial direction. However, according to the present invention, the tubular spacer provided between the journal pipe and the notch does not form the cam piece. You may make it regulate the floating in the axial direction.

(6) In the above embodiment, the high pressure fluid is pumped into the central hole of the shaft body as a means for bulging the shaft body. However, according to the present invention, the diameter expansion treatment is performed inside the central hole. It is also possible to insert the tool and press the shaft main body from the inside with the diameter expanding jig to expand and deform the shaft main body.

[Brief description of drawings]

FIG. 1 is a side view of the first embodiment.

FIG. 2 is a front view of the shaft body.

FIG. 3 is a front view of a cam piece.

FIG. 4 (A) is a front view showing a fitted state of a shaft body and a cam piece before bulging, and (B) is a partially enlarged front view showing a fitted state of a shaft body and a cam piece before bulging.

FIG. 5A is a front view showing a fitted state of a shaft body and a cam piece after bulge processing. FIG. 5B is a partially enlarged front view showing a fitted state of a shaft body and a cam piece after bulge processing.

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

7 is a sectional view taken along line BB of FIG.

FIG. 8 is a vertical cross-sectional view showing a fitted state of the shaft body and the cam piece before the bulge processing.

FIG. 9 is a vertical cross-sectional view showing the fitted state of the shaft body and the cam piece after bulging.

FIG. 10 is a partially enlarged view of FIG.

[Explanation of symbols]

10 ... Shaft body 13 ... Projection 20 ... Cam piece 23 ... Shaft hole 24 ... Recess 25 ... Notch 25A ... The rear end face of the notch

Claims (6)

[Claims] 1. A tubular shaft body having a convex portion formed on an outer periphery thereof, and a cam piece having a concave portion formed on an inner periphery of an axial hole, wherein the convex portion and the concave portion are fitted to each other. With the shaft body penetrating the shaft hole, the shaft body is expanded and deformed by bulge processing so that the convex portion bites into the concave portion, so that the shaft body and the cam piece are integrally rotatable. A composite camshaft characterized in that 2. The composite camshaft according to claim 1, wherein the convex portion and the concave portion have a trapezoidal shape that becomes narrower toward the radially outer side. 3. A notch formed in a pair that is open to the axial hole of the cam piece is formed on both axial end faces of the cam piece so as to form a pair, and the outer peripheral portion of the shaft body is bited into the notch by bulging. The composite camshaft according to claim 1 or 2, wherein the cam piece and the shaft main body are coupled to each other in the axial direction. 4. The composite camshaft according to claim 3, wherein an innermost end surface in the axial direction of the inner surface of the cutout portion forms an acute angle with the inner peripheral surface of the shaft hole. 5. A structure in which a convex portion is formed on the outer periphery of a tubular shaft body and a concave portion is formed on the inner periphery of the shaft hole of the cam piece, and the convex portion and the concave portion are fitted to each other, With the shaft body penetrating the shaft hole, the shaft body is expanded and deformed by bulge processing so that the convex portion bites into the concave portion, so that the shaft body and the cam piece are integrally rotatable. A method for manufacturing a composite camshaft, comprising: 6. A structure in which a notch portion that opens in the axial hole of the cam piece is formed in pairs on both axial end surfaces of the cam piece, and the shaft main body is formed in the notch portion by bulging. The method for manufacturing a composite camshaft according to claim 5, wherein the cam piece and the shaft body are coupled in the axial direction by biting the outer peripheral portion of the.