JP2019138324A - Electromagnetic clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic latch which is not damaged even when an abnormal torque is applied to a rotor while reducing the weight. A drive-side rotating body comprises a cylindrical resin pulley 4 having a groove 40 on which a belt for transmitting a rotational driving force is mounted, and a magnetic circuit through which a magnetic flux that generates an electromagnetic force is passed. The rotor 3 is made of metal, and the inner peripheral surface of the pulley 4 and the outer peripheral surface of the rotor 3 are joined to each other. Then, the joint surface of the rotor 3 with the pulley 4 is roughened so that the joint strength of the joint surface of the pulley 4 with the rotor 3 is equal to or higher than the belt slip torque between the belt and the groove 40. [Selection diagram] Fig. 2

Description

  The present invention relates to an electromagnetic clutch.

  2. Description of the Related Art Conventionally, an electromagnetic clutch includes a cylindrical pulley having a V-groove formed on an outer peripheral surface, and a magnetic circuit and a rotor that are disposed inside the pulley and form a magnetic circuit. In this electromagnetic clutch, the pulley and the rotor are integrated by welding after the rotor is press-fitted inside the pulley.

  In such an electromagnetic clutch, the pulley diameter varies depending on the vehicle type, engine type, and the like of the vehicle on which it is mounted. Designing the magnetic circuit, pulley diameter, and rotor diameter to be different depending on the vehicle type, engine type, etc. results in poor efficiency both in design and production. Therefore, the magnetic circuit and the rotor are made common and the pulley diameter is varied. It corresponds in this way.

  Further, in such an electromagnetic clutch, the pulley does not need to be a magnetic body because it does not form a magnetic circuit, but is generally formed using a metal such as carbon steel, like the rotor. However, when the pulley is made of metal as described above, the weight becomes heavy, and the fuel efficiency of the mounted vehicle is deteriorated.

  Therefore, there is an increasing demand for weight reduction of electromagnetic clutches, and studies are being made to configure a portion that does not form a magnetic circuit using a material (for example, resin) that is lighter than metal. As for pulleys, the use of resin has been studied but has not been put to practical use.

  In Patent Document 1, a plurality of convex portions are formed on the outer peripheral surface of a rotor by a casting process, the rotor is put in a mold, and a synthetic resin pulley is insert-molded. An integrated electromagnetic clutch is described. Moreover, what was described in the said patent document 1 is ensuring the coupling | bonding strength of a rotor and resin pulley parts by forming uneven | corrugated shape in the outer peripheral surface of a rotor part.

Japanese Patent No. 2932217

  However, Patent Document 1 does not describe the strength of the joint between the synthetic resin pulley and the rotor. For example, when the compressor shaft is stuck and cannot rotate, abnormal torque is applied to the rotor. When applied, stress may concentrate on the plurality of convex portions, and the synthetic resin pulley may be damaged.

  The present invention has been made in view of the above points, and an object thereof is to provide an electromagnetic clutch that is light in weight and that is not damaged even when an abnormal torque is applied to the rotor.

  In order to achieve the above object, the invention described in claim 1 is an electromagnetic clutch, which is a drive-side rotating body (3, 4) that rotates about a rotation axis (J) by a rotational driving force output from a driving source. ) And a driven side that is arranged on one side of the rotating shaft with respect to the driving side rotating body, is attracted to the driving side rotating body by electromagnetic force, and is connected to the driving side rotating body to rotate around the rotating shaft A rotating body (5), and the driving side rotating body has a cylindrical pulley (4) having a groove (40) to which a belt for transmitting a rotational driving force is mounted, and an electromagnetic force. And a metal rotor (3) that constitutes a magnetic circuit through which a magnetic flux that generates a magnetic field passes, and the inner peripheral surface of the pulley and the outer peripheral surface of the rotor are bonded to each other. The strength should be higher than the belt slip torque between the belt and the groove. Roughening treatment is performed on the joint surface of the pulley in the other.

  According to such a configuration, the drive-side rotator generates electromagnetic force with the resin-made pulley (4) having a groove shape (40) in which the belt for transmitting the rotational drive force is mounted and the cylindrical shape. And a metal rotor (3) that constitutes a magnetic circuit through which the magnetic flux is passed, the inner peripheral surface of the pulley and the outer peripheral surface of the rotor are joined, and the joining strength of the joined surface with the rotor of the pulley is Roughening is applied to the joint surface of the rotor with the pulley so that the belt slip torque between the belt and the groove is equal to or greater, so that the weight is reduced and electromagnetic waves that do not break even when abnormal torque is applied to the rotor. A latch can be provided.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is sectional drawing of the electromagnetic clutch which concerns on 1st Embodiment. It is sectional drawing of the electromagnetic clutch which concerns on 2nd Embodiment. It is sectional drawing of the electromagnetic clutch which concerns on 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
An electromagnetic clutch according to a first embodiment of the present invention will be described with reference to FIG. The electromagnetic clutch according to the present embodiment is used in a vehicle air conditioner to intermittently transmit a rotational driving force output from a vehicle running engine as a driving source to a refrigerant compressor as a driving target device. .

  As shown in FIG. 1, the electromagnetic clutch includes an electromagnet 1, a rotor 3, a pulley 4, an armature 5, a hub 7, and the like. The rotor 3, the pulley 4, the armature 5, and the hub 7 rotate about the rotation axis J.

  The electromagnet 1 includes a stator 11 and a coil 12. The electromagnet 1 generates an electromagnetic force when the coil 12 is energized to connect the rotor 3 and the armature 5.

  The stator 11 is made of a magnetic material (specifically, iron). The stator 11 is a cylindrical stator outer cylindrical portion 111 disposed coaxially with the rotation axis J, and is disposed on the inner peripheral side of the stator outer cylindrical portion 111 and coaxial with the rotation axis J. And the stator inner cylindrical portion 112 arranged in the center, and the stator outer cylindrical portion 111 and the stator inner cylindrical portion 112 extend in the direction perpendicular to the rotational axis so as to connect the one end side in the rotational axis, and the front and back surfaces of the central portion And a disk-shaped stator end surface portion 113 in which a circular through-hole penetrating the shaft is formed.

  That is, the stator 11 has a double cylindrical structure, and its axial cross-sectional shape is two U-shapes that are positioned line-symmetrically with respect to the rotation axis J, and the inner peripheral surface of the stator outer cylindrical portion 111, the stator A cylindrical space is formed by the outer peripheral surface of the inner cylindrical portion 112 and the inner surface of the stator end surface portion 113. And the coil 12 is accommodated in the cylindrical space.

  The coil 12 is fixed to the stator 11 while being molded with an insulating resin material (specifically, epoxy), and is electrically insulated from the stator 11.

  One end of the coil 12 is electrically grounded to the vehicle side, and the other end of the coil 12 is connected to an electronic control unit (ECU) 100 of the air conditioner. The electronic controller 100 performs switching control between energization and non-energization of the coil 12.

  The rotor 3 has a cylindrical rotor outer cylindrical portion 31 that is coaxially disposed with respect to the rotational axis J, and is disposed on the inner peripheral side of the rotor outer cylindrical portion 31 and coaxially with respect to the rotational axis J. And a cylindrical rotor inner cylindrical portion 32. Further, the rotor 3 extends in the direction perpendicular to the rotation axis so as to connect one end side in the rotation axis direction of the rotor outer cylindrical portion 31 and the rotor inner cylindrical portion 32, and a circular through hole penetrating the front and back is formed in the center portion. The disk-shaped rotor end surface portion 33 and the like are formed.

  That is, the rotor 3 has a double cylindrical structure, and its axial cross-sectional shape is two U-shapes that are positioned line-symmetrically with respect to the rotation axis J, and the inner peripheral surface of the rotor outer cylindrical portion 31, the rotor A cylindrical space is formed by the outer peripheral surface of the inner cylindrical portion 32 and the inner surface of the rotor end surface portion 33. And the electromagnet 1 is accommodated in the cylindrical space.

  The rotor outer cylindrical portion 31, the rotor inner cylindrical portion 32, and the rotor end surface portion 33 are made of a magnetic material such as low carbon steel and constitute a magnetic circuit G that passes the magnetic flux of the electromagnet 1.

  That is, the rotor 3 constitutes a part of a magnetic circuit G that passes a magnetic flux that generates an electromagnetic force for attracting the armature 5.

  The rotor end surface portion 33 is formed of a plurality of plates 331 to 333 that are formed in an annular shape around the rotation axis J and are arranged in the radial direction around the rotation axis J.

  Specifically, the rotor end surface portion 33 includes a rotor outer plate 331 that is continuous with the rotor outer cylindrical portion 31, a rotor inner plate 332 that is continuous with the rotor inner cylindrical portion 32, and a space between the rotor outer plate 331 and the rotor inner plate 332. The rotor intermediate plate 333 is arranged.

  On the armature 5 side of the plates 331 to 333, rotor friction surfaces 331a to 333a that come into contact with the armature 5 when the rotor 3 and the armature 5 are connected are formed.

  The rotor outer plate 331 and the rotor intermediate plate 333 form an annular outer groove 334 with the rotation axis J as the center. Further, the rotor intermediate plate 333 and the rotor inner plate 332 form an annular inner groove 335 centering on the rotation axis J.

  The outer groove 334 is positioned on the outer peripheral side of the inner groove 335. The outer groove 334 and the inner groove 335 correspond to a magnetic blocking part that blocks a magnetic flow between the plurality of plates 331 to 333, respectively.

  A groove portion 40 on which a belt (not shown) is hung is formed on the outer peripheral side of the pulley 4. The belt transmits the rotational driving force output from the engine to the rotor 3. The pulley 4 of the present embodiment is made of resin, and is integrated with the rotor outer cylindrical portion 31 by insert molding.

  The outer peripheral side of the ball bearing 36 is fixed to the inner peripheral side of the rotor inner cylindrical portion 32, and the inner peripheral side of the ball bearing 36 is connected to the electromagnetic clutch side from the housing that forms the outer shell of the refrigerant compressor (not shown). A cylindrical boss portion (not shown) protruding to the side is fixed. Thereby, the rotor 3 is rotatably fixed with respect to the housing of a refrigerant compressor. Note that the rotor 3 and the pulley 4 correspond to a drive side rotating body of the present invention.

  The armature 5 is a disk-shaped member made of a magnetic material that spreads in the vertical direction of the rotation axis J and has a circular through hole penetrating the front and back at the center. The armature 5 includes an inner plate 53 in which a circular through hole is formed, an outer plate 54 provided on the outer peripheral side of the inner plate 53, and a leaf spring member 55. The inner plate 53 and the outer plate 54 are each made of a magnetic material (for example, iron). The armature 5 corresponds to the driven side rotating body of the present invention.

  The rotor outer cylindrical portion 31, the rotor inner cylindrical portion 32, and the rotor end surface portion 33 are coated to prevent corrosion.

  The leaf spring member 55 is a disk-like elastic member in which a circular through hole penetrating the front and back is formed at the center. The leaf spring member 55 is formed with a plurality of rivet insertion holes 55a and a plurality of rivet insertion holes 55d for inserting the rivets 540.

  An armature friction surface 51 that contacts the rotor friction surfaces 331a to 333a of the rotor end surface 33 when the rotor 3 and the armature 5 are connected is formed on the surface of the inner plate 53 and the outer plate 54 on the rotor 3 side. Yes.

  A groove-shaped slit 56 is provided between the inner plate 53 and the outer plate 54. The slit 56 is positioned between the outer groove 334 and the inner groove 335. The slit 56 has a shape that is continuous in the circumferential direction about the rotation axis J.

  The hub 7 connects the armature 5 and the refrigerant compressor, and is coupled to the shaft of the refrigerant compressor. The hub 7 is a rotating member that rotates by being connected to the rotor 3. The hub 7 includes a cylindrical cylindrical portion 71 that extends in the direction of the rotation axis J, and a flange portion 72 that extends in a direction perpendicular to the rotation axis J from one end side of the cylindrical portion 71.

  A leaf spring member 55 that extends in a direction perpendicular to the rotation axis J is disposed between the hub 7 and the outer plate 54. A plurality of rivet insertion holes (not shown) for inserting the rivets 520 are formed in the flange portion 72 of the hub 7. A rivet 520 is inserted into a rivet insertion hole 55 a formed in the leaf spring member 55 and a rivet insertion hole 72 a formed in the flange portion 72 of the hub 7, and the leaf spring member 55 is fixed to the hub 7 by the rivet 520. .

  The outer plate 54 is formed with a plurality of rivet insertion holes 54d for inserting the rivets 540. A rivet 540 is inserted into a rivet insertion hole 54 d formed in the outer plate 54 and a rivet insertion hole 55 b formed in the plate spring member 55, and the plate spring member 55 is fixed to the outer plate 54 by the rivet 540. The inner plate 53 and the outer plate 54 are fixed to a leaf spring member 55.

  The leaf spring member 55 applies an elastic force in a direction in which the armature friction surface 51 is separated from the rotor end surface portion 33. Due to this elastic force, when the coil 12 is not energized, a predetermined gap is formed between the rotor end surface portion 33 and the armature friction surface 51.

  In the electromagnetic clutch of the present embodiment, the joint surface of the rotor 3 with the pulley, that is, the cylinder, is such that the joint strength of the joint surface of the pulley 4 and the rotor 3 is equal to or greater than the belt slip torque between the belt and the groove 40 of the pulley 4. The outer peripheral surface of the cylindrical rotor outer cylindrical portion 31 is subjected to a roughening process.

  In the present embodiment, irregularities are formed on the outer peripheral surface of the rotor outer cylindrical portion 31 by knurling the outer peripheral surface of the rotor outer cylindrical portion 31 using a knurling tool.

  A resin pulley 4 is integrally formed on the outer peripheral surface of the rotor outer cylindrical portion 31 by insert molding.

  Further, in the electromagnetic clutch according to the present embodiment, a roughening process is performed on the joint surface of the rotor outer cylindrical portion 31 of the rotor 3 with the pulley 4. Thereby, when the pulley 4 is insert-molded into the rotor 3, the thermosetting resin for forming the pulley 4 enters the unevenness formed on the outer peripheral surface of the rotor outer cylindrical portion 31, and is cured there to be bonded. (Anchor effect) can be obtained. Due to such an anchor effect, the joint strength of the joint surface between the pulley 4 and the rotor 3 is further increased. Thus, the joining strength of the joining surface of the pulley 4 and the rotor 3 is equal to or higher than the belt sliding torque between the belt and the groove 40.

  Next, the basic operation of the electromagnetic clutch of this embodiment will be described. When the electronic control device 100 does not output a control voltage and the electromagnet 1 is in a non-energized state, the electromagnet 1 does not generate an electromagnetic force, so that the rotor 3 and the armature 5 are elastic of the leaf spring member 55. Separated by force. Therefore, the rotational driving force of the engine is not transmitted to the refrigerant compressor. As a result, the refrigeration cycle device does not operate.

  When the electronic control device 100 outputs a control voltage and puts the electromagnet 1 into an energized state, the electromagnetic force generated by the electromagnet 1 exceeds the elastic force of the leaf spring member 55, and the armature 5 moves toward the rotor 3 by the electromagnetic force. The rotor friction surfaces 331a to 333a and the armature friction surface 51 are brought into pressure contact with each other, and the rotor 3 and the armature 5 are connected. Accordingly, the rotational driving force of the engine is transmitted to the refrigerant compressor via the rotor 3, the armature 5, and the hub 7. Thereby, the refrigeration cycle apparatus operates.

  Further, when the shaft of the compressor is fixed and cannot rotate while the rotor 3 is rotating, the joining strength of the joining surface of the pulley 4 and the rotor 3 is greater than the belt slip torque between the belt and the groove 40. Since the belt starts to slide with respect to the pulley 4 before the pulley 4 is damaged, the pulley 4 is prevented from being damaged.

  As described above, the electromagnetic clutch includes the drive-side rotator (3, 4) that rotates about the rotation axis (J) by the rotational drive force output from the drive source. Further, a driven-side rotation that is arranged on one side of the rotating shaft with respect to the driving-side rotating body, is rotated around the rotating shaft by being attracted to the driving-side rotating body by electromagnetic force and connected to the driving-side rotating body. It has a body (5). The drive-side rotator has a cylindrical pulley (4) having a groove (40) in which a belt for transmitting a rotational driving force is mounted, and a magnetic circuit that passes a magnetic flux that generates electromagnetic force. And an inner peripheral surface of the pulley and an outer peripheral surface of the rotor are joined to each other. And the roughening process is given to the joint surface with the pulley in a rotor so that the joint strength of the joint surface with the rotor of a pulley may become more than the belt slip torque between a belt and a groove part.

  According to such a configuration, the drive-side rotator generates electromagnetic force with the resin-made pulley (4) having a groove shape (40) in which the belt for transmitting the rotational drive force is mounted and the cylindrical shape. A metal rotor (3) constituting a magnetic circuit through which the magnetic flux to be passed is passed, and the inner peripheral surface of the pulley and the outer peripheral surface of the rotor are joined. And the roughening process is given to the joint surface with the pulley in a rotor so that the joint strength of the joint surface with the rotor of a pulley may become more than the belt slip torque between a belt and a groove part. Therefore, it is possible to provide an electromagnetic latch that can be reduced in weight and that is not damaged even when an abnormal torque is applied to the rotor.

(Second Embodiment)
The electromagnetic clutch of 2nd Embodiment is demonstrated using FIG. In the electromagnetic clutch according to the first embodiment, a recess 37 that is recessed along the circumferential direction is formed on the outer peripheral surface of the rotor 3. Further, the bottom surface of the recess 37 is roughened. Specifically, the bottom surface of the recess 37 is roughened so that the joining strength of the joining surface of the pulley 4 and the rotor 3 is equal to or higher than the belt sliding torque between the belt and the groove 40 of the pulley 4.

  In the electromagnetic clutch of this embodiment, the rotor outer cylindrical portion 31, the rotor inner cylindrical portion 32, and the rotor end surface portion 33 are coated to prevent corrosion. Here, it is difficult for the coating material to be applied to the interface between the pulley 4 and the rotor outer cylindrical portion 31 of the rotor 3.

  For this reason, for example, when raindrops adhere to the rotor 3, the raindrops enter the interface between the rotor outer cylindrical portion 31 of the rotor 3 and the pulley 4, and corrosion of the rotor 3 proceeds.

  However, in the electromagnetic clutch of the present embodiment, the concave portion 37 that is recessed along the circumferential direction is formed on the outer peripheral surface of the rotor 3. For this reason, even if raindrops enter the interface between the rotor 3 and the pulley 4, the raindrops are prevented from entering the recesses 37 and the rotor 3 is prevented from corroding.

  Moreover, since the recessed part 37 is formed in the outer peripheral surface of the rotor 3, compared with the case where the recessed part 37 is not formed in the outer peripheral surface of the rotor 3, the area of the joint surface of the rotor 3 and the pulley 4 should be enlarged. The joint strength of the joint surface between the rotor 3 and the pulley 4 can be further increased.

  In the present embodiment, the same effect obtained from the configuration common to the first embodiment can be obtained as in the first embodiment.

(Third embodiment)
The electromagnetic clutch of 3rd Embodiment is demonstrated using FIG. The electromagnetic clutch of the present embodiment is formed so that the film portion 41 using the resin constituting the pulley 4 covers at least a part of the rotor 3.

  Specifically, the coating 41 using the resin constituting the pulley 4 includes a part of the rotor outer cylindrical portion 31 on the armature 5 side, a surface opposite to the armature 5 side of the rotor outer cylindrical portion 31, and the rotor. It is formed so as to cover the inner peripheral surface of the inner cylindrical portion 32 and the surface opposite to the armature 5 side of the rotor end surface portion 33. The formation of the film portion 41 is performed simultaneously with the formation of the pulley 4.

  Thus, by forming the film portion 41 using the resin constituting the pulley 4 so as to cover a part of the rotor 3, it is possible to make the coating of the rotor 3 unnecessary.

  In the present embodiment, the same effect obtained from the configuration common to the first embodiment can be obtained as in the first embodiment.

(Other embodiments)
(1) In each of the above embodiments, the outer peripheral surface of the rotor 3 is knurled so that the outer peripheral surface of the rotor 3 is roughened. For example, chemical unevenness is formed using a chemical or the like. A roughening process may be performed on the outer peripheral surface of the rotor 3 by an etching process, a laser process for forming irregularities using laser light, or the like. Further, when the rotor outer cylindrical portion 31 of the rotor 3 is cut, the outer peripheral surface of the rotor 3 may be roughened by actively roughening the cutting surface.

  (2) In the second embodiment, the concave portion 37 that is recessed along the circumferential direction is formed on the outer peripheral surface of the rotor 3, and the bottom surface of the concave portion 37 is roughened. Of these, the roughening process may be performed on the region other than the bottom surface of the recess 37. Further, a roughening process may be performed on the outer peripheral surface of the rotor 3 other than the bottom surface of the recess 37, and the roughening process may not be performed on the bottom surface of the recess 37.

  (3) In the said 3rd Embodiment, although the film | membrane part 41 using the resin which comprises the pulley 4 was formed so that a part of rotor 3 might be covered, for example, the film | membrane part 41 is made into a rotor. 3 may be formed so as to cover all of 3.

  In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, it is needless to say that elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Yes. Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case. In each of the above embodiments, when referring to the material, shape, positional relationship, etc. of the constituent elements, etc., unless otherwise specified, or in principle limited to a specific material, shape, positional relationship, etc. The material, shape, positional relationship, etc. are not limited.

(Summary)
According to the first aspect shown in part or all of the above embodiments, the electromagnetic clutch includes a drive-side rotator that rotates about a rotation axis by a rotational drive force output from a drive source. . Further, a driven-side rotation that is arranged on one side of the rotating shaft with respect to the driving-side rotating body, is rotated around the rotating shaft by being attracted to the driving-side rotating body by electromagnetic force and connected to the driving-side rotating body. Has a body. The drive-side rotator is made of a resin-made pulley having a groove portion on which a belt for transmitting a rotational drive force is mounted, and a metal circuit constituting a magnetic circuit for passing a magnetic flux that generates an electromagnetic force. And an inner peripheral surface of the pulley and an outer peripheral surface of the rotor are joined to each other. And the roughening process is given to the joint surface with the pulley in a rotor so that the joint strength of the joint surface with the rotor of a pulley may become more than the belt slip torque between a belt and a groove part.

  Moreover, according to the 2nd viewpoint, the recessed part recessed along the circumferential direction is formed in the outer peripheral surface of a rotor. Accordingly, for example, even if raindrops enter the interface between the rotor and the pulley, the penetration of raindrops into the recesses is suppressed, and corrosion of the rotor can be suppressed.

  Moreover, according to the 3rd viewpoint, the film using the resin which comprises the pulley is formed so that at least one part of a rotor may be covered. Therefore, it is not necessary to paint the rotor.

3 Rotor 4 Pulley 5 Armature 40 Groove 37 Recess 41 Film

Claims (3)

An electromagnetic clutch,
A drive-side rotating body (3, 4) that rotates about a rotation axis (J) by a rotational driving force output from a driving source;
A follower that is arranged on one side of the rotating shaft with respect to the driving side rotating body, is attracted to the driving side rotating body by electromagnetic force, and is connected to the driving side rotating body to rotate around the rotating shaft. A side rotating body (5),
The drive-side rotator is
A resin pulley (4) having a cylindrical shape having a groove (40) to which a belt for transmitting the rotational driving force is mounted;
A metal rotor (3) that constitutes a magnetic circuit that passes magnetic flux that generates the electromagnetic force, and
The inner peripheral surface of the pulley and the outer peripheral surface of the rotor are joined,
An electromagnetic clutch in which a roughening process is performed on a joint surface of the rotor with the pulley so that a joint strength of a joint surface of the pulley with the rotor is equal to or higher than a belt slip torque between the belt and the groove.   The electromagnetic clutch according to claim 1, wherein a concave portion (37) that is recessed along a circumferential direction is formed on an outer peripheral surface of the rotor.   The electromagnetic clutch according to claim 1 or 2, wherein a coating (41) using a resin constituting the pulley is formed so as to cover at least a part of the rotor.

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