JPH0454360Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a pulley formed by press working or roll working.

[Conventional technology]

Conventionally, this type of pulley has been used, for example, to drive a water pump shaft of an automobile engine.
FIG. 5 shows a conventional pulley 1 assembled on the shaft 4 of an automobile water pump, in which a belt is wound around a pulley main body 2 having a circular ring shape with an open center and a plurality of V-shaped grooves 3a on the outer circumferential side. Section 3 is provided.
This pulley 1 is fastened to a pulley seat 5 which is press-fitted onto a shaft 4 using bolts 6.

[The problem that the idea aims to solve]

As mentioned above, conventional pulleys have a structure that is assembled to the shaft by tightening bolts through the pulley seat, and the number of parts is large and the assembly process is time-consuming, resulting in a high-cost product. .

Therefore, a press-fit type pulley was developed, in which a press-fit part for press-fitting onto the shaft is provided on the inner circumferential side of the pulley main body by bending molding, allowing it to be assembled directly onto the shaft without using a pulley seat. has been done.

However, since this pulley has low rigidity at the edge of the press-fit part, the surface pressure at the edge of the fitting surface is small when it is press-fitted onto the shaft. The problem is that the torque transmission efficiency decreases due to slippage.

As a means to eliminate these difficulties, the fit of the press-fit part of the pulley should be an interference fit with a large interference margin, or the fit surface of the press-fit part should be a tapered surface that reduces in diameter toward the edge. It is conceivable to increase the fitting surface pressure by increasing the fitting surface pressure, but such a method has the disadvantage in terms of strength that a large stress is generated in the corner part connected to the pulley body on the opposite side from the edge part of the press-fit part. These problems hinder the practical use of press-fit pulleys.

The purpose of this invention is to solve the above problems and provide a press-fit type pulley that can obtain the necessary fitting surface pressure without increasing the interference of the press-fit portion.

[Means to solve the problem]

In order to achieve the above object, in this invention, a bent portion formed by bending toward the inner diameter side is provided at the end edge portion of the press-fitted portion of the pulley.

[Function] In the pulley of this invention, the edge portion of the press-fitting portion is reinforced by the bent portion formed by bending on the inner diameter side, so the surface pressure at the edge portion of the fitting surface of the press-fitting portion is reduced. growing.

Therefore, even when the press-fit portion has a large tightening allowance and sufficient torque transmission is obtained, the stress at the corner portion where the press-fit portion connects to the pulley body is reduced.

Further, the bent portion provided at the edge portion of the press-fit portion serves as a portion for positioning in the axial direction when assembling the pulley to the shaft.

〔Example〕

Hereinafter, embodiments of this invention will be described based on the drawings.

FIG. 1 is a longitudinal cross-sectional side view of the upper half of the pulley of this invention in a state assembled on a shaft.

The pulley 10 is formed by bending a belt winding part 12 and a press-fitting part 13 in the same axial direction by pressing and rolling on the outer circumferential side and the inner circumferential side of an annular pulley main body 11, respectively. The rotating part 12 is provided with a plurality of V-shaped grooves 12a, and the edge portion of the press-fitting part 13 is bent radially inward to form a bent part 14, and the center circular ring of the pulley 10 is bent. A circular hole 16 is formed in the inner diameter surface of the bent portion 14.

When assembling this pulley 10 to the shaft 20,
The press-fitting portion 13 is press-fitted onto the shaft 20 with the outer surface of the pulley main body 11 facing the end surface of the shaft 20 . Since the air in the internal space of the press-fitting part 13 is discharged to the outside from the circular hole 16 when the press-fitting part 13 is press-fitted, this air does not interfere with the press-fitting. Further, as the press-fitting portion 13 is press-fitted, the bent portion 14 comes into contact with the end face of the shaft 20, so that the press-fitting is completed at this point, and the pulley 10 is simultaneously positioned in the axial direction.

The pulley 10 having the above configuration has increased rigidity because the end edge portion of the press-fitting portion 13 is reinforced by the bent portion 14 that is bent toward the inner diameter side.

For this reason, the pulley 10 assembled on the shaft 20
The surface pressure distribution on the fitting surface of the press-fit portion ₁₃ is as shown in FIG.
The contact pressure P ₂ becomes approximately the same value, and a necessary and sufficient fitting contact pressure is obtained as a whole. Therefore, in the pulley 10 of this invention, there is no need to increase the interference of the press-fit portion 13 in order to obtain the required fitting surface pressure, and no large stress is generated in the corner portion 15.

FIG. 2 shows, as a comparative example, the surface pressure distribution on the fitting surface of the press-fitting part 13 for a pulley 10a in which the bent part 14 explained in FIG. 1 is not provided at the edge of the press-fitting part 13. However, it can be seen that the surface pressure P ₁ at the edge portion is significantly smaller than the surface pressure P ₂ at the corner portion 15.

3 and 4 are longitudinal sectional side views of the upper half of another embodiment of this invention, and the same components as in FIG. 1 are designated by the same reference numerals.

The pulley 10 in FIG. 3 has a cylindrical portion 17 on the inner circumferential side of a pulley main body 11 that is bent in the same axial direction as the belt winding portion 12, and a circle that is connected to the cylindrical portion 17 and bent in the radial direction. An annular portion 18 is provided, and this annular portion 18
A press-fitting part 13 is formed by bending in the axial direction opposite to the belt winding part 12 from the inner circumferential edge of the belt.

The pulley 10 shown in FIG. 4 has a cylindrical portion 17 bent in the same axial direction as the belt winding portion 12 at the center of the pulley main body 11 shown in FIG.

The pulley 10 configured as described above has a press-fit portion 1
The end edge portion of the fourth
In the figure, it is reinforced by the cylindrical part 17, so
The stress generated in the corner portion 15 can be further reduced.

In each of the above embodiments, a pulley with a plurality of V-shaped grooves on the belt winding part is illustrated, but a pulley with a single V-shaped groove on the belt winding part, or a pulley with a flat groove on the belt winding part is illustrated. This idea can also be applied to.

Regarding the press-fitting part of the pulley, this invention is not limited to a cylindrical press-fitting part, but may also be applied to a rectangular cylindrical press-fitting part.If this invention is applied to a square cylindrical press-fitting part, the pulley will be This can prevent slipping in the rotational direction.

[Effect of idea]

As explained above, according to this invention, the rigidity of the edge portion of the press-fitting part is reinforced by the bent part formed on the inner diameter side, thereby increasing the required fitting surface pressure. This not only eliminates the need to increase the interference of the press-fit part, but also reduces the stress generated at the corners where the press-fit part connects to the pulley main body, which solves the strength problem that had been an issue with press-fit pulleys. can be solved.

Furthermore, according to this invention, it is possible to press-fit the pulley onto the shaft and assemble it directly, which eliminates the need for a pulley seat and other mounting parts, improving assembly work efficiency. At the same time, a press-fit type pulley that is inexpensive and highly practical can be obtained.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional side view of the upper half of the pulley of this invention, showing the state in which it is assembled around the shaft and the fitting surface pressure distribution at the press-fitting part. FIGS. 3 and 4 are longitudinal sectional side views of the upper half showing the fitting surface pressure distribution of the parts, respectively, and FIG. is a vertical cross-sectional side view of the upper half of a conventional pulley assembled around the shaft. In the figure, 10 is a pulley, 11 is a pulley main body, 1
2 is a belt winding part, 13 is a press-fitting part, 14 is a bending part, and 20 is a shaft.

Claims (1)

[Scope of utility model registration request] On the outer circumferential side and inner circumferential side of the annular pulley body,
In a pulley in which a belt winding portion around which the belt is wound and a press-fitting portion press-fitted onto the shaft are respectively provided in the axial direction by bending, an edge portion of the press-fitting portion of the pulley is provided with a A pulley characterized by having a bent part formed by bending.