JP2003120706A - Fastening structure of rotary body and rotary shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent looseness of screw joining when joining a pulley to a shaft by a screw. SOLUTION: A second male screw part 212 is formed as an inverse directional screw to a first male screw part 211. Thus, when the pulley 100 loosens since large negative torque acts, the pulley 100 moves to the nut 213 side, and while, since a nut 213 fastens (moves to the pulley 100 side), looseness of the screw joining of the pulley 100 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening structure for a rotating body and a rotary shaft, and is effectively applied to a mounting structure for a power transmission device such as a pulley and an electromagnetic clutch.

[0002]

2. Description of the Related Art As a pulley mounting structure, for example, in the invention disclosed in Japanese Utility Model Laid-Open No. 2-67152, a male screw portion is formed on a shaft and a female screw portion is formed on a pulley. Both are fastened by screw connection.

At this time, the male screw portion and the female screw portion need to be formed in such a direction that the screws are tightened when torque acts on the pulley and the shaft. When a large torque fluctuation occurs, torque for loosening the screw (hereinafter, this torque is referred to as negative torque) acts on the pulley and the shaft,
If the negative torque is large, the screw connection between the pulley and the shaft may be loosened.

Incidentally, in the internal combustion engine, since the piston reciprocates due to intermittent combustion of fuel in the combustion chamber, the torque fluctuation is larger than that of a drive source such as an electric motor, so that negative torque is easily generated. The above problems are likely to occur.

In view of the above points, it is an object of the present invention to prevent the screw connection from loosening when the rotary body and the rotary shaft are screwed together.

[0006]

In order to achieve the above object, the present invention provides a rotating shaft (2
In 10), a first male screw part (211) that meshes with a female screw part (131) formed on the rotating body (100), and a second male screw part (211) having a screw in the opposite direction to the first male screw part (211) are formed.
A male screw part (212) is provided, and a nut (213) is fastened to the second male screw part (212) so as to face the side surface of the rotating body (100).

As a result, when a large negative torque acts to loosen the rotating body, the rotating body moves to the nut (213) side,
On the other hand, since the nut (213) is tightened (moves to the rotary body side), loosening of the screw connection of the rotary body is prevented.

By the way, when a positive torque, which is a reverse torque of a negative torque, acts on the nut (213), the nut (213) receives a loosening force (hereinafter, this force is referred to as a loose force). The larger the moment of inertia of the nut (213), the larger.

On the other hand, in the invention described in claim 2, the moment of inertia of the nut (213) is
Since it is smaller than the inertia moment of (00), the amount of loosening of the nut (213) (the amount of movement of the nut (213)) when a negative torque is generated can be suppressed to a small amount.

Therefore, since the loosening force acting on the nut (213) can be reduced, it is possible to prevent the nut (213) from loosening when the positive torque is applied. As a result, it is possible to reliably prevent the rotating body from loosening when a negative torque is applied.

Incidentally, the reference numerals in parentheses of the above-mentioned respective means are examples showing the correspondence with the concrete means described in the embodiments described later.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In this embodiment, a rotating body for transmitting a driving force from an engine, which is a drive source, to a compressor of a vehicle air conditioner, has a fastening structure of a rotating body and a rotating shaft according to the present invention. Which is applied to a pulley fastening structure as shown in FIG.
FIG. 4 is a cross-sectional view of the pulley 100 showing the pulley 100 assembled to the shaft 210 of the compressor 200.

In FIG. 1, a pulley body 110 is formed into a substantially cylindrical shape that is rotated by receiving a driving force (torque) from a traveling engine (not shown) via a V-belt (not shown). Alternatively, the cylindrical pulley hub 111 is made of hard resin (phenol resin in the present embodiment), and the radial rolling bearing 120 that rotatably supports the pulley body 110 is mounted on the inner peripheral side of the pulley body 110. Are integrally molded. Incidentally, the inner ring of the bearing 120 is mounted or press-fitted into the front housing of the compressor 200.

In this embodiment, the pulley body 110 is used.
As a pulley for a poly drive belt provided with a plurality of rows of V-shaped grooves 112 and a pulley main body 110 made of resin, the pulley hub 11
On the inner peripheral side of the bearing 1 where the bearing 120 is mounted, a metal sleeve 113 is formed by insert molding on the pulley hub 111.
Is integrated into.

The inner hub 130 is made of metal which is located on the inner peripheral side of the pulley body 110 and is arranged coaxially with the pulley body 110 to rotate.
The outer peripheral side of 0 is provided with a damper 140, which is a torque transmission member made of an elastic material (EPDM (ethylene / propylene / diene terpolymer rubber in this embodiment)) having a hardness lower than that of the inner hub 130. The inner peripheral side of the pulley body 110 mechanically engages with and meshes with the pulley body 110.

The inner hub 130 is the compressor 2
00 has a cylindrical portion 133 having a through hole 132 formed with a first male screw portion 211 formed on the outer peripheral surface of the shaft 210 and a female screw portion 131 threadedly coupled thereto, and an annular portion 135 having a protrusion 134 meshing with the damper 140. , And the annular portion 135 and the cylindrical portion 133 are mechanically coupled to transmit torque from the annular portion 135 to the cylindrical portion 133,
A plurality of (three in the present embodiment) bridge portions 1 having a strength set to break when the torque transmitted from the annular portion 135 to the cylindrical portion 133 exceeds a predetermined torque.
36 (see FIG. 2) and the like.

The bridge portion 136 and the cylindrical portion 133 are integrally formed by sintering metal powder, and the bridge portion 136 and the annular portion 135 are formed by integrally forming the bridge portion 135 and the cylindrical portion 133. The annular portion 135 is integrated by injecting the resin into the mold (insert molding) in a state of being arranged in the mold for resin molding.

Further, the inner hub 130 has at least the female screw portion 131 formed thereon, and then has a coating for corrosion prevention formed on the surface thereof by the dacro treatment. In addition, the Dakuro treatment is performed by immersing the object to be treated in a decomposition aqueous solution (treatment solution) of metallic zinc flakes, chromic anhydride, etc., and then heating the object to be treated at about 300 ° C. in a baking furnace,
Hexavalent chromium is reduced by an organic substance such as glycol to bond zinc flakes to an object to be treated to form a film. By the way, chromic anhydride oxidizes the surface of the metal substrate to chemically bond with the object to be treated, thereby generating a strong adhesive force.

By the way, as shown in FIG. 3, the first male screw portion 211 formed on the shaft 210 has a first male screw portion 211 at the front end side thereof.
A second male screw portion 212 having a thread opposite to the male screw portion 211 is provided, and a nut 213 that comes into contact with the side surface of the pulley 100 is fastened to the second male screw portion 212.

In the present embodiment, the first male screw portion 2
The screw 11 has a direction in which the first male screw portion 211 and the female screw portion 131 are tightened when the torque that drives the compressor 200 (hereinafter, the torque in this direction is referred to as positive torque) acts on the pulley 100. Is formed, and the second male screw portion 2 is formed.
The screw 12 is formed on the screw 12 so that the nut 213 and the second male screw portion 212 are tightened when the negative torque acts on the pulley 100.

In this embodiment, the pulley 100 is inserted into the shaft 210 from the tip end side of the shaft 210 and screwed to the first male screw portion 211, and then the nut 213 is inserted from the tip end side of the shaft 210 to the second male screw portion 212. Therefore, the screw diameter of the second male screw portion 212 is smaller than the screw diameter of the first male screw portion 211.

Further, the washer 214 is the first male screw portion 21.
The washer 214 is fitted to the stepped portion on the root side, and the female screw portion 131 is prevented from excessively biting into the root side of the first male screw portion 211 due to the axial force acting on the pulley 100 by the washer 214. To prevent.

Next, the general operation of the joint 100 according to this embodiment will be described.

The torque transmitted to the pulley body 110 is
It is transmitted to the inner hub 130 via the damper 140. At this time, the damper 140 compressively deforms in the rotation direction (circumferential direction) of the pulley 110, thereby transmitting torque from the pulley 110 to the inner hub 130 while absorbing torque fluctuation.

Then, from the pulley 110 to the inner hub 1
When the torque transmitted to 30 reaches or exceeds a predetermined value, the bridge portion 136 breaks, so that the torque transmission from the pulley body 110 to the inner hub 130 is interrupted. That is,
The bridge portion 136 functions as a torque limiter mechanism that prevents transmission of torque equal to or greater than a predetermined value.

Next, the features (effects) of this embodiment will be described.

When a large negative torque acts to loosen the pulley 100, the pulley 100 moves to the nut 213 side, while the nut 213 tightens (moves to the pulley 100 side), so that the pulley 100 is screwed. It is prevented from loosening.

By the way, when a positive torque acts, the nut 213 is loosened (hereinafter, this force is referred to as a loose force).
However, this loosening force increases as the moment of inertia of the nut 213 increases.

On the other hand, in this embodiment, the nut 2
Since the inertial moment of 13 is sufficiently smaller than the inertial moment of the pulley 100, the amount of loosening of the nut 213 (the amount of movement of the nut 213) when a negative torque is generated can be suppressed to a small amount. Therefore, the nut 21
Since the loosening force acting on 3 can be reduced, the nut 213 can be prevented from loosening when the positive torque acts. As a result, it is possible to reliably prevent the pulley 100 from loosening when a negative torque is applied.

In this embodiment, the second male screw part 212 is used.
Is sufficiently small (for example, the first male screw part 2
If it is smaller than 11, the loosening of the nut 213 can be suppressed, which is more effective.

(Other Embodiments) In the above-mentioned embodiment, in the above-mentioned embodiment, the metric coarse screw (JIS
However, the present invention is not limited to this, and a metric fine screw (JIS B 02) is used.
07) or other thread standards such as inch thread.

Further, in the above-described embodiment, the present invention is applied to the fastening structure of the pulley for transmitting the driving force from the engine to the compressor of the vehicle air conditioner. The application of the present invention is not limited to this. Absent.

The nut 213 is not limited to the so-called nut (JIS B 1181).

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a pulley mounting structure according to an embodiment of the present invention.

FIG. 2 is a front view of the pulley according to the embodiment of the present invention.

FIG. 3 is an enlarged sectional view showing a pulley mounting structure according to the embodiment of the present invention.

[Explanation of symbols]

100 ... pulley (rotating body), 210 ... shaft, 211
... 1st external thread part, 212 ... 2nd external thread part, 213 ... Nut.

Claims (3)

[Claims] 1. A fastening structure for a rotating body (100) and a rotating shaft (210), wherein the rotating shaft (210) meshes with a female screw portion (131) formed on the rotating body (100). A first male screw part (211) and a second male screw part (212) having a screw in a direction opposite to that of the first male screw part (211) are provided, and the second male screw part (212) is further provided. The nut (213) is tightened so as to face the side surface of the rotating body (100). 2. The fastening structure for a rotating body and a rotating shaft according to claim 1, wherein an inertia moment of the nut (213) is smaller than an inertia moment of the rotating body (100). 3. A power transmission device for transmitting torque generated by an internal combustion engine to a rotating device (200), wherein a rotating body (10) receiving torque generated by the internal combustion engine.
0) and the rotating shaft (210) of the rotating device (200) are connected by the fastening structure of the rotating body and the rotating shaft according to claim 1 or 2. .