JPH10148223A - Shaft for electromagnetic clutch and electromagnetic clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost by simplifying a manufacturing process. SOLUTION: A shaft 34 comprises a cylindrical body 38 which has a circular cross sectional passing hole 35 in an axial center direction and is formed of a metallic material having magnetism that a shaft SF on a rotation transmission side is inserted in this passing hole 35, and a detent member 40 which is arranged at least in one end part of the cylindrical body 38 and prevents the rotation of the shaft SF on the rotation transmission side in the cylindrical body 38. The detent member 40 is formed of a detent part 44 arranged along the inner circumferential surface of the cylindrical body 38, and a positioning part 46 arranged by being brought into tight with a passing hole 42 formed into a shape having a taper in a direction where the frontage of an inner circumferential surface side is formed narrower than a peripheral surface side formed in the cylindrical body 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electromagnetic clutch shaft and an electromagnetic clutch, and more particularly, to an electromagnetic clutch shaft and an electromagnetic clutch capable of reducing costs.

[0002]

2. Description of the Related Art A conventional electromagnetic clutch is constructed, for example, as shown in FIG. The electromagnetic clutch shown in FIG. 1 is applied to a paper feeding mechanism of a copying machine, and has a housing 206 having an opening 202 on one surface and a bottom 204 on the other opposite surface, and an opening 2 of the housing 206.
Field 2 composed of cover 208 covering
10 is provided. The bottom 204 of this field 210
The bearing 21 is inserted into a through hole 212 formed at the center thereof.
4 is disposed, and the cover 208 of the field 210 is provided with:
A bearing 218 is provided in a through hole 216 formed in the center.

[0003] The field 210 has a bottom 204.
The shaft 220 is rotatably disposed through the bearing 214 of the cover 208 and the bearing 218 of the cover 208. The shaft 220 has a through hole 221 formed in the axial direction thereof.
And a small-diameter portion 222 and a large-diameter portion 224 along the axial direction. The small-diameter portion 222 penetrates the bearing 214, and the large-diameter portion 224 penetrates the bearing 218. A cylindrical body 226 is rotatably fitted to the outer periphery of the small-diameter portion 222 of the shaft 220 so that a part of the cylindrical body 226 protrudes outside the bottom portion 204 of the field 210. This cylinder 226
The gear 228 is located on the outer periphery of the
Are fitted.

In the field 210, an exciting coil 23 is provided.
0 is loosely fitted to the outer periphery of the cylindrical body 226 and is fixed to the bottom 204 side. In the field 210, a support member 234 is provided at a position adjacent to the exciting coil 230.
An armature 238 is attached to the support member 234 via a leaf spring 236 on the cover 208 side. The support member 234 is integrally connected to the cylinder 226 by a coil spring 240, and is rotatable together with the cylinder 226.
In the field 210, a rotor 2 having a slit 242 is formed at a position adjacent to the armature 238.
44 is integrally attached to the shaft 220.

[0005] The electromagnetic clutch constructed as described above
When the cylindrical body 226 rotates around the outer periphery of the shaft 220 due to the rotation of the gear 228 by an external driving source, the support member 234 rotates together with the cylindrical body 226, whereby the armature 238 rotates.

Now, when the exciting coil 230 is energized,
Shaft 220, housing 206 of field 210
A magnetic flux is generated by the excitation coil 230 in a magnetic path formed by the rotor 244 and the rotor 244, and an attracting force is generated in the rotor 244 by a leakage magnetic flux generated in the slit 242 of the rotor 244. Therefore, the armature 238 is
It is attracted to the rotor 244 against the elastic force of 36. As a result, the rotor 244 is rotated by the drive source rotating the gear 228, and the shaft 220 integrated with the rotor 244 is rotated.

On the other hand, when the energization to the excitation coil 230 is cut off, the magnetic flux disappears, and the attraction force between the rotor 244 and the armature 238 disappears. As a result, the armature 238 is supported by the elastic force of the leaf spring 236. Member 234
Side, and separates from the rotor 244. As a result, even if the gear 228 rotates, the shaft 2
The rotation of 20 stops.

In the electromagnetic clutch configured as described above, the shaft 220 has an inner diameter at the end of the small-diameter portion 222 according to the cross-sectional shape of the shaft constituting the paper feed mechanism inserted therethrough, as shown in FIG. It may be necessary to form a detent shape such as a D-shaped cross section as shown. In this case, since it is difficult to obtain the shaft 220 by cutting the metal bar due to the shape of the inner diameter portion, the inner diameter portion of one end portion of the magnetic material powder has a D-shaped cross section. It was obtained by sintering at high temperature what was formed into a cylindrical shape having a detent shape.

[0009]

However, the shaft 2
When the sintered body 20 is made of a sintered body as described above, a number of steps such as a molding step and a baking step are required, and in addition, deformation occurs inevitably during sintering due to unevenness in material density during molding. Therefore, after sintering, the shape must be corrected by a polishing means or the like so as to have a predetermined shape, and there is a problem that it is difficult to reduce the cost of the shaft 220. As a result, there is a problem that the cost of the electromagnetic clutch is restricted.

[0010] Accordingly, an object of the present invention is to provide an electromagnetic clutch shaft and an electromagnetic clutch having a detent shape at an inner diameter portion capable of reducing costs by simplifying a manufacturing process.

[0011]

According to a first aspect of the present invention, there is provided an electromagnetic clutch shaft having a through-hole having a circular cross section in an axial direction, the through-hole having a shaft on the rotation transmission side. A cylindrical body made of a magnetic material having magnetic properties inserted therein, and disposed at least at one end of the cylindrical body,
A rotation preventing member for preventing rotation of the shaft in the cylinder.

In the shaft for an electromagnetic clutch according to the first aspect, the cylindrical body made of a magnetic metal material forms a part of a magnetic path through which a magnetic flux generated from the exciting coil passes. In addition, the rotation-preventing member prevents the rotation-receiving shaft inserted into the cylinder from rotating in the cylinder, and the rotation of the electromagnetic clutch shaft is efficiently transmitted to the rotation-receiving shaft.

According to a second aspect of the present invention, there is provided an electromagnetic clutch shaft according to the first aspect, wherein the cylindrical body has an engaging portion formed on an inner peripheral surface thereof. Is composed of a detent portion provided along a part of the inner peripheral surface of the cylindrical body, and a positioning portion connected to the detent portion and engaged with the engaging portion. It is characterized by being.

In the shaft for an electromagnetic clutch according to the second aspect, the detent portion provided along a part of the inner peripheral surface of the cylindrical body is engaged with the engaging portion on the inner peripheral surface of the cylindrical body. Is fixed in the cylinder by the positioning portion.

According to a third aspect of the present invention, in the electromagnetic clutch shaft according to the second aspect, the engaging portion is
It is a through hole penetrating the outer peripheral surface of the cylindrical body, this through hole,
The front end of the cylindrical body on the inner peripheral surface side is tapered in a direction to become narrower than the front end on the outer peripheral surface side.

In the shaft for an electromagnetic clutch according to the third aspect, the positioning portion engaged with the through hole of the cylindrical body is prevented from being pulled out of the through hole, and the rotation preventing portion is securely fixed in the cylindrical body. You.

According to a fourth aspect of the present invention, there is provided an electromagnetic clutch shaft according to the third aspect, wherein the cylindrical body has a circumferential groove formed on an outer peripheral surface thereof so as to communicate with the through hole. The rotation preventing member is characterized in that it is provided with a retaining portion that is connected to the positioning portion and is engaged with the groove.

In the electromagnetic clutch shaft according to the fourth aspect, the positioning portion provided in the through hole of the cylindrical body is pulled out of the through hole by the retaining portion engaged with the groove on the outer peripheral surface of the cylindrical body. Is prevented, and the rotation preventing portion is securely fixed in the cylinder.

According to a fifth aspect of the present invention, there is provided an electromagnetic clutch shaft according to any one of the first to fourth aspects, wherein the detent member is made of a resin formed by insert molding. And In the electromagnetic clutch shaft according to the fifth aspect, the detent member is easily formed on the cylindrical body.

According to a sixth aspect of the present invention, there is provided an electromagnetic clutch, which is provided on a field, a shaft penetrating through the inside of the field and rotatably attached to the field, and attached to a shaft in the field and provided from outside. An input-side rotator that rotates around a shaft by a rotational force; an output-side rotator connected to the shaft in the field; and an excitation coil disposed around the shaft in the field. When the input-side rotating body and the output-side rotating body are magnetically attracted and connected to each other when a coil is energized, the rotation of the input-side rotating body is transmitted to the output-side rotating body. An electromagnetic clutch shaft according to any one of claims 1 to 5 is used as the shaft.

In the electromagnetic clutch according to the sixth aspect, the shaft for the electromagnetic clutch according to the first to fifth aspects has exactly the same function as that of a conventional sintered body. Exactly the same performance is maintained.

[0022]

FIG. 1 is a sectional view of an electromagnetic clutch to which an electromagnetic clutch shaft according to the present invention is applied.
FIG. 2 is a cross-sectional view showing only a shaft for an electromagnetic clutch (hereinafter, simply referred to as a shaft) as viewed from the right side of FIG.
In these figures, the electromagnetic clutch has an opening 12 on one side.
And a field 20 composed of a cylindrical housing 16 having a bottom portion 14 on the other opposite surface, and a plate-like cover 18 covering the opening 12 of the housing 16.

A through hole 28 is formed at the center of the bottom portion 14 of the housing 16, and a bearing 29 is fitted into the through hole 28. The through hole 28 has a detent shape having a linear portion in part, and a fitting portion of the bearing 29 to the through hole 28 has a shape matching the through hole 28. The cover 18 is provided with a rotation preventing protrusion 30 protruding in a radial direction on a peripheral edge thereof.
A through hole 31 is formed at the center, and a bearing 32 is fitted into the through hole 31.

In the field 20, a shaft 34 is rotatably disposed through the bearing 29 of the bottom portion 14 and the bearing 32 of the cover 18. The shaft 34 has a through hole 35 having a circular cross section formed in the axial direction thereof, and has a small-diameter portion 36 slightly longer than 全長 of the entire length and a large-diameter portion 37 slightly shorter than the small-diameter portion 36. Cylindrical body 38
And a detent member 40 disposed at an end of the cylindrical body 38 on the side of the small diameter portion 36. The small diameter portion 36 penetrates the bearing 29, and the large diameter portion 37 penetrates the bearing 32. I have.

At the end of the small diameter portion 36 of the cylindrical body 38, a through hole 42 is formed for communicating the outer peripheral surface and the inner peripheral surface.
The through hole 42 is for positioning the rotation preventing member 40 as described later, and has a truncated conical shape having a taper in a direction in which a frontage on the inner peripheral surface side is narrower than the outer peripheral surface side of the cylindrical body 38. ing. Further, a washer groove 43 is formed on the outer peripheral surface of the end of the small diameter portion 36 of the cylindrical body 38 in the circumferential direction. The rotation preventing member 40 prevents the shaft SF such as the paper feed mechanism of the copying machine, which is the rotation receiving side shaft inserted into the through hole 35 on the small diameter portion 36 side, from rotating in the through hole 35. Rotation of the shaft S on the rotation receiving side
F is to be efficiently transmitted.

The detent member 40 is provided along a part of the inner peripheral surface of the through hole 35 of the cylindrical body 38, and has a shape of the through hole 35 on the side where the shaft SF on the rotation receiving side is inserted. Detent part 44 having a D-shaped cross section, and detent part 4
4 and a positioning portion 46 which is disposed in engagement with the through hole 42. In addition, the detent member 40 is formed by insert molding in which an end of the cylindrical body 38 on the small diameter portion 36 side is arranged in a mold (not shown) and a liquid resin is poured into the mold and cured. Things. The detent part 4 of the detent member 40
4 can be changed to various shapes according to the cross-sectional shape of the shaft on the rotation transmission side.

A cylindrical fitting body 48 is rotatably fitted to the outer periphery of the end of the small diameter portion 36 of the cylindrical body 38 so that a part of the cylindrical body 38 projects outside the bottom portion 14 of the field 20. . A gear 50 as a driving force transmitting member is fitted to an outer position of the field 20 on the outer periphery of the fitting body 48 so as to be able to rotate together with the fitting body 48, and the washer is fitted into the washer groove 43 of the cylindrical body 38. 51 are fitted and the fitting body 48
Is prevented from coming out of the cylinder 38, and the gear 50
Is prevented from getting out of the fitting body 48.

A coil spring 56 as a connecting member is fitted in the cylindrical body 38 so as to extend over the outer periphery of the large diameter portion 37 and the outer periphery of the fitting body 48. This coil spring 56
One end 58 located on the fitting body 48 side is the coil spring 5
6, the other end 60 located on the large diameter portion 37 side is bent toward the outer periphery of the coil spring 56,
One end 58 is locked in a locking hole 49 formed in the fitting body 48. The coil spring 56 is connected to the other end 6.
The coil spring 56 is wound in a direction in which the coil spring 56 is tightened when a clockwise rotational force as viewed from the right side in FIG.

In the field 20, a through hole 6 is provided at the center.
An excitation coil 64 having a width 2 is loosely fitted around the outer periphery of the coil spring 56 and is fixed to the bottom portion 14 by means of adhesive or the like, and a lead 66 of the excitation coil 64 is drawn out of the field 20. A plate-like support member 70 having a through hole 68 having a diameter larger than the outer diameter of the coil spring 56 at the center thereof is fitted to the outer periphery of the coil spring 56 at a position adjacent to the exciting coil 64. Have been.

The support member 70 has a recess 72 formed continuously with the through hole 68, and the other end 60 of the coil spring 56 is locked in the recess 72 and connected to the fitting body 48. It is rotatable together with the fitting body 48.
In addition, a plate-shaped armature 76 having a through hole 74 having a diameter larger than the large diameter portion 37 of the shaft 34 at the center is attached to the support member 70 via a leaf spring 78 on the cover 18 side. At a position adjacent to the armature 76, a plate-shaped rotor 82 having a plurality of arc-shaped slits 80 formed in the circumferential direction is integrally attached to the large-diameter portion 37 of the shaft 34.

The support member 70 and the armature 76 constitute an input-side rotating body that is directly rotated by an external drive source. The rotor 82 is turned on when the exciting coil 64 is energized. Is transmitted and rotated, and constitutes an output-side rotator that stops rotating when power supply to the exciting coil 64 is cut off. At least the field 20, the cylinder 38, the armature 76 and the rotor 82 constituting the shaft 34 are made of a magnetic material such as an iron-based metal, and the gear 50 and the support member 70 are made of a non-magnetic material such as a resin. It is made of material. Further, the cover 18 constituting the field 20 is
After each component is disposed in the opening 12, it is disposed in the opening 12,
Thereafter, it is swaged at a predetermined position and fixed to the housing 16.

The electromagnetic clutch configured as described above
The shaft SF of the paper feeding mechanism or the like is a small-diameter portion 36 of the shaft 34.
Is inserted in a state where the rotation is stopped by the rotation preventing member 40, and the rotation preventing projection 30 formed on the cover 18 is fixed to a fixing member inside a device such as a copying machine so that the field 20 does not rotate. In such a state, a rotational force that rotates clockwise as viewed from the right side in FIG. 1 is applied to the gear 50 from an external drive source. Accordingly, the fitting member 48 rotates around the outer circumference of the shaft 34, and the support member 70 rotates together with the fitting member 48, whereby the armature 76 rotates.

When the excitation coil 64 is energized, a magnetic flux is generated by the excitation coil 64 in a magnetic path indicated by a chain line M formed through the shaft 34, the housing 16 of the field 20, and the rotor 82, and the rotor 82 Adsorption force is generated in the rotor 82 by the leakage magnetic flux generated in the slit 80. Therefore, the armature 76 is attracted to the rotor 82 against the elastic force of the leaf spring 78. As a result, the rotor 82 is rotated by the drive source that rotates the gear 50, and the shaft 34 integrated with the rotor 82 is rotated. Due to this rotation, the shaft SF on the rotation receiving side inserted into the end of the small diameter portion 36 of the shaft 34
Rotates.

On the other hand, when the power supply to the exciting coil 64 is cut off, the magnetic flux disappears, and the attracting force between the rotor 82 and the armature 76 disappears. As a result, the armature 76
Is pulled back toward the support member 70 by the elastic force of the leaf spring 78 and separates from the rotor 82. As a result, even if the gear 50 is rotating, the rotation of the shaft 34 is stopped.

The shaft 34 for an electromagnetic clutch according to the present invention
Is composed of the cylindrical body 38 and the detent member 40, so that it has exactly the same function as that of the conventional sintered body, but the manufacturing process can be simplified and the cost can be reduced. As a result, the cost of the electromagnetic clutch using the same can be reduced.

In the embodiment shown in FIGS. 1 and 2, the detent member 40 constituting the shaft 34 is
The positioning part 46 is used as the cylindrical body 3 constituting the shaft 34.
8, the positioning portion 46 is prevented from falling out of the through hole 42 by being disposed by being engaged with the through hole 42 having a tapered shape formed in 8, so that the rotation preventing portion 44 becomes the inner periphery of the cylindrical body 38. Although it is surely fixed to the surface, a concave portion having the same taper shape as the through hole 42 may be provided on the inner peripheral surface instead of the through hole 42 as the engaging portion. Also in this case, the positioning portion 46 is engaged with the concave portion serving as the engagement portion, and the rotation preventing portion 44 can be securely fixed to the inner peripheral surface of the cylindrical body 38. Further, the rotation preventing portion 44 can be reliably fixed to the inner peripheral surface of the cylindrical body 38 also by the configuration as shown in FIG.

That is, as shown in FIGS. 3 (a) and 3 (b), instead of the through hole 42, a frontage between the outer peripheral surface side and the inner peripheral surface side is formed at the end of the cylindrical body 38 constituting the shaft 34. A through hole 90 having the same size is formed, and a circumferential groove 92 communicating with the through hole 90 is formed on the outer peripheral surface of the cylindrical body 38. The cylindrical body 38 having such a through hole 90 and the groove 92 is disposed in a mold,
By pouring a liquid resin into this mold, FIG.
As shown in (c) and (d), the rotation preventing portion 94 disposed on the inner peripheral surface of the cylindrical body 38 and the rotation preventing portion 94 Continuous positioning part 9
6 and a retaining member 98 that is disposed in engagement with the groove 92 and that is continuous with the positioning portion 96. In the configuration shown in FIG. 3, the through hole 90 may have a tapered shape as shown in FIGS. 1 and 2, and the groove 92 may have a ring shape surrounding the outer peripheral surface.

In the embodiment shown in FIGS. 1 and 2, the detent member 40 is made of a resin formed by insert molding, but may be made of a metal material, for example. That is, in the case of using a metal material, the positioning portion 46 provided in the through hole 42
After the positioning portion 46 is inserted into the through hole 42 and is beaten from the outer peripheral surface side of the cylindrical body 38, it is deformed so as to conform to the inner shape of the through hole 42. I just need.

In the embodiment shown in FIGS. 1 and 2, the detent member 40 is formed by insert molding. However, for example, the detent member 40 may be configured as follows. That is, as shown in FIG. 4A, the through hole 102 having the same size in the outer peripheral surface side and the inner peripheral surface side is formed in the cylindrical body 38, while, as shown in FIG. A detent portion 104 provided on the inner peripheral surface of the cylindrical body 38, and a through hole 102 formed integrally with the outer peripheral surface of the detent portion 104.
A detent member 108 having a positioning part 106 disposed in advance is formed in advance from a resin material, a metal material, or the like, and the detent member 108 is attached to the inner peripheral surface of the cylindrical body 38 and the through hole 102 with an adhesive. To fix.

It is to be noted that a recess formed in the inner peripheral surface of the cylindrical body 38 may be used instead of the through hole 102. Alternatively, the detent member may be formed of only the detent portion, and the detent portion may be attached to the inner peripheral surface of the cylindrical body. In this case, a through hole or the like is not required in the cylindrical body. Further, while a projection as an engaging portion is locked on the inner peripheral surface of the cylindrical body, a concave portion to be engaged with the projection is formed in the rotation preventing portion, and the projection and the concave portion are fitted. The rotation preventing portion may be fixed to the inner peripheral surface of the cylindrical body.

In the embodiment shown in FIGS. 1 and 2, the detent member 40 is provided at the end of the small-diameter portion 36 of the cylindrical body 38. It is also possible to dispose it at the end of 37, and it is also possible to dispose it over the entire area of the cylindrical body 38.

Further, in the embodiment shown in FIGS. 1 and 2, the exciting coil 64 is disposed on the bottom surface 14 side of the housing 16 forming the field 20 and the rotor 8
2 is disposed on the side of the cover 18 constituting the field 20, the excitation coil 64 may be disposed on the side of the cover 18 and the rotor 82 may be disposed on the side of the bottom surface 14. Further, the support member 70 and the armature 76 serve as an input-side rotator, and the rotor 82 serves as an output-side rotator. However, the rotor 82 serves as an input-side rotator, and the support member 70 and the armature 76 may be an output side rotating body. In short, any configuration other than the electromagnetic clutch shaft 34 other than the electromagnetic clutch shaft 34 can be adopted.

[0043]

As described above, according to the first aspect of the present invention,
Since the shaft for the electromagnetic clutch is constituted by the cylindrical body made of a metal material and the detent member provided at at least one end of the cylindrical body, its manufacturing process is simplified as compared with the one made of a sintered body. Cost can be reduced.

According to the second aspect of the present invention, the cylindrical body has a through hole communicating the outer peripheral surface and the inner peripheral surface thereof, and the detent member is provided on the inner peripheral surface of the cylindrical body. And a positioning portion disposed in close contact with the through hole, so that the rotation preventing portion is positioned by the positioning portion disposed in the through hole of the cylindrical body. Can be positioned and fixed.

According to the third aspect of the present invention, the through-hole has a taper in a direction in which a frontage on the inner peripheral surface side of the cylindrical body is narrower than a frontage on the outer peripheral surface side. As a result, the positioning portion disposed in the through hole is prevented from being pulled out of the through hole, so that the rotation preventing portion can be securely fixed in the cylinder.

According to the fourth aspect of the present invention, the cylindrical body has a circumferential groove formed on the outer peripheral surface thereof, the circumferential groove communicating with the through hole. Since it is provided with the fixing portion which is provided continuously and is arranged in close contact with the groove, the detent portion can be securely fixed in the cylinder.

According to the fifth aspect of the present invention, since the detent member is made of resin formed by insert molding, the detent member can be easily formed on the cylindrical body.

According to the invention of claim 6, according to claim 1,
Since the electromagnetic clutch is configured using any one of the shafts for electromagnetic clutches, the cost can be easily reduced despite maintaining the same performance as the conventional electromagnetic clutch.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electromagnetic clutch to which an electromagnetic clutch shaft according to an embodiment of the present invention is applied.

FIG. 2 is a side sectional view of an electromagnetic clutch shaft according to the present invention applied to the electromagnetic clutch shown in FIG. 1;

3A and 3B are diagrams illustrating a structure of a shaft for an electromagnetic clutch according to another embodiment of the present invention, wherein FIG. 3A is a cross-sectional view of a main part of a cylinder constituting the shaft, and FIG. FIG. 4 is an external perspective view of the cylindrical body, (c) is a cross-sectional view of a main part of the cylindrical body provided with a rotation preventing member, and (d) is a side cross-sectional view of the cylindrical body illustrated in (c).

4A and 4B are diagrams illustrating a structure of a shaft for an electromagnetic clutch according to another embodiment of the present invention, wherein FIG. 4A is a cross-sectional view of a main part of a cylinder constituting the shaft, and FIG. It is a perspective view.

FIG. 5 is a sectional view of a conventional electromagnetic clutch.

FIG. 6 is a diagram illustrating a cross-sectional shape of an electromagnetic clutch shaft.

[Explanation of symbols]

 12 Opening 14 Bottom 16 Housing 18 Cover 20 Field 34 Shaft 35 Through-hole 36 Small-diameter portion 37 Large-diameter portion 38 Cylindrical 40, 100, 108 Detent member 42, 90, 102 Through-hole 44, 94, 104 Detent portion 46, 96, 106 Positioning part 64 Excitation coil 70 Support member 76 Armature 78 Leaf spring 82 Rotor 98 Retaining part

Claims (6)

[Claims] 1. A cylindrical body made of a magnetic metal material having a through-hole having a circular cross section in the axial direction, into which a shaft on the rotation receiving side is inserted, and at least one end of the cylindrical body. And a detent member for preventing rotation of the shaft in the cylindrical body. 2. The cylindrical body has an engaging portion formed on an inner peripheral surface thereof, and the detent member is disposed along a part of the inner peripheral surface of the cylindrical body. 2. The electromagnetic clutch shaft according to claim 1, wherein the shaft comprises a detent portion and a positioning portion connected to the detent portion and engaged with the engaging portion. 3. The engaging portion is a through hole that penetrates the outer peripheral surface of the cylindrical body, and the through hole has a smaller width at the inner peripheral surface side than at the outer peripheral surface side of the cylindrical body. 3. The shaft for an electromagnetic clutch according to claim 2, wherein the shaft has a shape having a taper in a direction. 4. The cylindrical body has a circumferential groove formed in the outer peripheral surface thereof and communicating with the through hole. The rotation preventing member is provided continuously with the positioning portion, and The shaft for an electromagnetic clutch according to claim 3, further comprising a retaining portion engaged with the groove. 5. The electromagnetic clutch shaft according to claim 1, wherein the rotation preventing member is made of a resin formed by insert molding. 6. A field, a shaft penetrating through the interior of the field and rotatably attached to the field, and being attached to a shaft in the field and rotating around the shaft by a rotational force applied from the outside. An input-side rotator, an output-side rotator connected to a shaft in the field, and an excitation coil disposed around the shaft in the field, wherein the input-side rotator is energized when the excitation coil is energized. An electromagnetic clutch wherein a body and the output side rotating body are magnetically attracted and connected to each other, and the rotation of the input side rotating body is transmitted to the output side rotating body. 5. An electromagnetic clutch, wherein the electromagnetic clutch shaft according to any one of 5) is used.