JP2001336548A - Electromagnetic clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve response and operation reliability of a thermal-link. SOLUTION: A cut end part of an exciting coil and a lead wire of a thermal- link are connected to a connection part 29 provided on a coil cover 26 of a coil bobbin by a terminal. Ultraviolet curing and humidity curing silicone resin is filled in the connection part 29 with separating in several times of applies. Moreover, ultraviolet lay is irradiated for curing silicone resin to form a resin coating layer 35 on the connection part 29.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic clutch mounted on a refrigerant compressor of an automobile, and more particularly, to an electromagnetic clutch provided with a thermal fuse connected in series with an exciting coil. is there.

[0002]

2. Description of the Related Art An electromagnetic clutch mounted on an automotive refrigerant compressor includes an armature supported on a rotating shaft side of the compressor by an elastic member, and a nose of a compressor housing which faces the armature with an air gap therebetween. A rotor rotatably supported by the section and an exciting coil for generating a magnetic flux for magnetically attracting the armature to the rotor against the elastic return force of the elastic member are provided. In addition, the exciting coil is formed into a predetermined outer diameter and a predetermined length by winding and solidifying a wire made of a self-fused wire a plurality of times, and also forms a slack portion in the middle of winding and cuts it. By doing so, a pair of cut ends is provided. Further, the exciting coil is held by a coil bobbin including a bobbin main body fitted on one end face side and a coil cover covered on the other end face side. Further, the coil cover is provided with a connection portion where the cut end of the excitation coil and the lead of the thermal fuse are electrically connected by terminals. An electromagnetic clutch having such a configuration is disclosed in
The electromagnetic clutch described in Japanese Patent Application Publication No. 0-37978 (hereinafter referred to as Prior Invention 1) is typical.

[0003] In the electromagnetic clutch of the prior invention 1, a connecting portion surrounded by a peripheral wall protruding in the opening direction of the coil accommodating groove and extending in the circumferential direction of the coil cover is integrally formed on a side surface of the coil cover exposed from the coil accommodating groove of the yoke. Is formed. Hereinafter, the structure of the connection portion of the coil cover will be briefly described with reference to FIGS. FIG. 12 is a plan view of a part of the yoke, FIG. 13 is a plan view of a part of the coil cover, and FIG.
FIG. 14 is a sectional view taken along line AA of FIG. 13.

The coil cover 1 of the first invention is an annular member made of a synthetic resin material having an annular groove 1a formed on the exciting coil 7 (only the cut ends 7a and 7b are shown). The yoke 2 is fitted in the coil receiving groove 2a. Further, on the side surface 1b of the coil cover 1 exposed from the coil accommodating groove 2a, a connection portion 3 which is surrounded on all sides by peripheral walls (side plates 3a, 3b, 3c, 3d) protruding from the side surface 1b is integrally formed. I have. Still further, the connecting portion 3
A fuse holding portion 4 having a holding groove 4a in which a case 8b of the thermal fuse 8 is fitted, a pair of coil extraction holes 4b from which cut ends 7a and 7b of the exciting coil 7 are extracted, A lead engaging groove 5a provided on both sides of the holding portion 4 and into which the lead 8a of the thermal fuse 8 is engaged, and a coil engaging groove into which the cut ends 7a and 7b of the exciting coil 7 are engaged. 5b, and a terminal press-fit portion 5 having a pair of terminals 5c for terminal engagement orthogonal to the grooves 5a and 5b.

[0005] In the coil cover 1 provided with the connecting portion 3 having such a configuration, the temperature fuse 8 is assembled by fitting the case 8b into the holding groove 4a while engaging the lead 8a in the groove 5a. . The cut ends 7a and 7b of the exciting coil 7 are pulled out from the coil extraction holes 4b when the coil cover 1 is put on the exciting coil 7, and are bent in the circumferential direction of the coil cover 1 to form grooves 5a.
b. Furthermore, the exciting coil 7 and the thermal fuse 8 are connected in series by engaging the side plate portion (not shown) of the terminal 6 with the groove 5c.

In the electromagnetic clutch according to the first aspect of the present invention, when the load on the rotary shaft of the compressor is increased and frictional heat is generated by slip rotation between the armature connected to the rotary shaft and the rotor connected to the crank pulley and the belt. , Connection part 3
, And the temperature fuse 8 is blown. Further, the power supply to the exciting coil 7 is cut off, the magnetic attraction of the magnetic flux disappears, and the armature is separated from the rotor. Therefore, the electromagnetic clutch of the first aspect of the invention can solve the problem that the belt hung on the belt groove of the rotor is cut.

[0007]

In the electromagnetic clutch of the first invention, the connecting portion 3 is covered with a fuse cover (not shown) and ultrasonically welded, so that the set fusing temperature in the connecting portion 3 is 184. The temperature fuse 8 at a temperature of 8 ° C. was housed. However, in a high-load electromagnetic clutch mounted on a compressor having a large discharge pressure and a large discharge amount, the temperature fuse 8 is not operated during normal operation of the compressor, due to the use environment of the mounted vehicle. It was thought that it could be activated (blown). Further, for example, when the fusing set temperature is 21
If a temperature fuse of 6 ° C. is used, heat conductivity is not preferable in the connection portion 3, and the operating time from when the peripheral temperature starts to rise due to slip rotation between the armature and the rotor until the thermal fuse is blown becomes longer. Therefore, there was a risk that the belt might be cut before the power transmission by the electromagnetic clutch was interrupted.

Means for solving such a problem include:
It is known that a case of a thermal fuse is exposed to the outside without covering a fuse cover like an electromagnetic clutch disclosed in Japanese Patent Application Laid-Open No. 11-201190 (Prior Invention 2).
However, although the thermal conductivity is improved and the responsiveness of the thermal fuse is improved, there is a problem of rust prevention and corrosion prevention of the thermal fuse case. In addition, there is a thermal fuse in which a part of the case is not insulated, and the technique of the prior art 2 cannot be directly employed.

When a thermal fuse in which a part of the case is not insulated is employed, the coil cover 1 of the prior invention 1 is provided with a holding groove 4 for retaining the case 8b of the thermal fuse 8.
Since the coil extraction hole 4b for extracting the cut ends 7a and 7b of the excitation coil 7 was formed near the end of "a",
In order to prevent the non-insulated case 8b from coming into contact with the cut ends 7a, 7b, they had to be arranged at a sufficient interval.

However, in an electromagnetic clutch mounted on an automotive refrigerant compressor, the groove width of the coil accommodating groove 2a of the yoke 2 depends on the size of the bearing fitted on the inner peripheral surface of the rotor and the outer peripheral surface of the rotor. Since it is limited by the size of the belt groove provided, the holding groove 4a for holding the case 8b and the coil extraction hole 4b for extracting the cut ends 7a and 7b cannot be designed with a sufficient space. In particular, the electromagnetic clutch of the first invention is formed by pressing a plurality of caulking pieces 2b for holding the exciting coil 7 in the coil accommodating groove 2a on the side face of the coil cover 1 on the open end face of the yoke 2. To form, the side plate 3 of the connection part 3
b and the opening end of the yoke 2 could not be brought close to each other.

The coil cover 1 according to the first aspect of the present invention is designed so that the cut ends 7a and 7b of the exciting coil 7 can be drawn into the connecting portion 3 in consideration of workability.
The insertion openings of a and 7b were formed in a conical (tapered) shape. However, the insertion opening is narrow, and the cut ends 7a and 7b have corner portions (indicated by P and Q in FIG.
Part) was sometimes scratched. Such a problem is caused by increasing the angle R shown in FIG.
The problem can be solved by widening the insertion opening of the coil end b, but the peripheral wall of the coil extraction hole 4b is thin and the strength is insufficient.
It was considered that the peripheral wall of the coil extraction hole 4b was likely to be damaged when a and 7b were extracted.

An object of the present invention is to improve the responsiveness and operational reliability of a thermal fuse.

[0013]

In order to solve the above-mentioned problems, an electromagnetic clutch according to a first aspect of the present invention includes a yoke in which an exciting coil held in a coil bobbin is housed in a coil housing groove, and a peripheral wall protruding from a side surface. A cut end of the exciting coil, which is opened in the same direction as the coil accommodating groove and is connected to the coil bobbin where the lead of the thermal fuse is connected by a terminal, is provided. It is characterized by being filled with a moisture-curable silicone resin.

According to a second aspect of the present invention, there is provided an electromagnetic clutch in which a connection portion of a heated coil bobbin is filled with an ultraviolet-curable and moisture-curable silicone resin in appropriate amounts in several portions, and air bubbles which have appeared on the surface of the resin are blown by a breeze. The resin filled in the connection portion is cured by irradiating ultraviolet rays and leaving the resin to stand after the removal.

According to a third aspect of the present invention, the connecting portion of the coil bobbin has a fuse holding portion formed at the bottom with a holding groove for holding a case of a thermal fuse, and a lead engaging groove extending in parallel. Grooves for engaging cut ends, and terminal engaging grooves orthogonal to these grooves are formed, and terminal press-in portions provided on both sides in the longitudinal direction of the holding grooves, and the fuse holding portion of each terminal press-in portion And a coil extraction portion provided with a coil extraction hole from which a cutting end of the excitation coil is extracted, and a cutting end of the excitation coil is bent toward the terminal press-in portion to cut the excitation coil. It is characterized in that it is engaged in an end engaging groove.

The electromagnetic clutch according to a fourth aspect of the present invention is characterized in that the coil outlet has an outlet formed by a peripheral wall protruding from the bottom of the coil outlet.

[0017]

1 to 11 show an electromagnetic clutch mounted on a refrigerant compressor for a vehicle shown as an embodiment of the present invention. 1 is a cross-sectional view of an electromagnetic clutch, FIG. 2 is a plan view of an exciting device of FIG. 1, FIGS. 3 to 5 are plan views showing only main parts of FIG. 2, and FIG. FIG. 4 is a plan view of a main part in which a casting resin and terminals are omitted, and FIG. 5 is a plan view of a main part in FIG. FIG. 6 shows terminals, (a) is a bottom view,
(B) is a side view. 7 to 11 are coil covers, FIG. 7 is a sectional view taken along line BB of FIG. 3, FIG. 8 is a sectional view taken along line CC of FIG. 3, FIG. 9 is a sectional view taken along line DD of FIG. FIG.
3 is a sectional view taken along line EE of FIG. 3, and FIG. 11 is a sectional view taken along line FF of FIG.

An electromagnetic clutch 10 mounted on the vehicle refrigerant compressor 9 includes an armature assembly spline-fitted to a rotating shaft 9a of the compressor 9 and integrally fixed by a backing plate 11 and bolts 12; A rotor 14 rotatably supported by a bearing 13 on a cylindrical nose portion 9c formed in a housing 9b of the compressor 9;
A yoke assembly supported by the horn is provided.

The armature assembly has a boss portion 15 having a spline hole into which the rotating shaft 9a is spline-fitted.
a, a hub 15 having a flange 15b extending radially outward from the boss 15a, a stopper plate 17 fixed to the flange 15b of the hub 15 with a plurality of rivets 16, and In the state where the through hole 17a of the stopper plate 17 formed at a position where the through hole 17a is divided into several parts and the through hole 18a having the same center as the through hole 17a are formed at the bottom, the through hole 17a and the through hole 18a are aligned. A plurality of rubber covers 18 welded to the outer surface of the stopper plate 17, a plurality of damper rubbers 19 individually fitted in the respective rubber covers 18, and a through hole formed at the center of the damper rubber 19. Through hole 1
A plurality of headed cylindrical torque transmitting pins 20 penetrating through the through holes 17a and 8a, and a small-diameter cylindrical portion provided on the inner surface of the stopper plate 17 and formed at the tip of the torque transmitting pins 20 is crimped. And an armature 21 connected to the torque transmission pin 20 is provided. Reference numeral 21a is a circular arc-shaped long hole formed on the armature 21 at a circumferential interval for magnetic flux detour.

The rotor 14 has an inner cylindrical portion 14a in which the bearing 13 is fitted and retained, and a belt groove 22 on the outer peripheral surface.
Are formed on the outer cylindrical portion 14b,
a, 14b are connected to each other, and the outer surface is connected to an armature 21.
A disk portion 14c is provided as a friction surface opposed to the friction surface of FIG. 1 with an air gap G, and an annular groove 14d opened to the housing 9b side is formed. Note that reference numeral 14e
Is an arc-shaped slot for magnetic flux detour formed in the disk portion 14c at intervals in the circumferential direction.

The yoke assembly is integrally mounted on the compressor 9 by fixing a mounting plate 24 welded to the back surface of the yoke 23 to the side surface of the housing 9b. Further, the yoke 23 is formed with an annular coil receiving groove 23a opened on the disk portion 14c side of the rotor 14, and is inserted into the annular groove 14d of the rotor 14. Furthermore, the coil accommodating groove 23
The end surface 23b of the inner pole portion serving as the inner peripheral wall of the a and the end surface 23c of the outer pole portion serving as the outer peripheral wall of the coil accommodating groove 23a face the inner surface of the disk portion 14c of the rotor 14 at an interval. In addition, an annular space S is provided between the opening of the coil accommodating groove 23a and the disk portion 14c.

An exciting coil 27 held by a coil bobbin including a bobbin body 25 and a coil cover 26 is housed in the coil housing groove 23 a of the yoke 23. The bobbin main body 25 is formed with an annular groove in which one end face of the exciting coil 27 is fitted, and has a terminal engaging portion formed through a through hole formed in the bottom of the yoke 23 at the bottom.
Although not shown, the winding start end and the winding end of the exciting coil 27 drawn out to the terminal engagement portion are electrically connected to the terminals of the terminal housing 28 that is press-fitted into the terminal engagement portion. . The connection structure between the winding end of the excitation coil 27 and the terminal employs a structure described in JP-A-10-231860, JP-A-11-31264, or the like.

The coil cover 26 has the shape shown in FIGS. 3, 7 to 11, and the like. That is, the coil cover 26 is an annular member made of a resin material having an annular groove 26a formed on one end surface side of the exciting coil 27, and a side surface opposite to the opening direction of the annular groove 26a includes: Side plates 26b, 26c extending in the tangential direction of an arbitrary reference circle (not shown) of the coil cover 26 and protruding from the side surfaces.
Connection part 29 surrounded by a peripheral wall formed by 26d and 26e
Are integrally formed. The connecting portion 29 protrudes from the coil accommodating groove 23a into the space S as shown in FIG. 1, and its opening is close to the inner side surface of the disk portion 14c of the rotor 14.

The connecting portion 29 includes a fuse holding portion 30 located at the center in the longitudinal direction and a fuse holding portion 3.
The terminal press-fitting portions 31 formed on both sides of the “0”, and the coil pull-out portions 32 formed on the opposite side of each terminal press-fitting portion 31 to the fuse holding portion 30 are provided. A semi-cylindrical holding groove 30 a in which a cylindrical case 33 a of the thermal fuse 33 is placed is formed at the bottom of the fuse holding unit 30.
In addition, each terminal press-fitting portion 31 is provided with a holding groove 30 at an interval.
The groove 31a for engaging the cut end portion and the groove 31b for engaging the lead, which extend in the longitudinal direction of "a", and the groove 31c for engaging the terminal formed at intervals so as to be orthogonal to the grooves 31a, 31b. Are formed.

Further, the coil extraction portions 32 provided at both ends of the connection portion 29 are formed with coil extraction holes 32a from which the cut ends 27a and 27b in the middle of the winding of the exciting coil 27 are extracted. The coil extraction hole 32a is formed in the annular groove 26a.
A stepped conical insertion opening 32b opened to the side and an outlet 32d formed by an annular peripheral wall 32c protruding from the bottom are provided.

The connecting portion 29 having such a structure includes:
The pair of cut ends 27a and 27b of the exciting coil 27 drawn out from the coil drawing hole 32a are formed into grooves 3 for engaging the cut ends.
1a. Further, in the connection portion 29, each lead 33b of the thermal fuse 33 in which the case 33a is fitted in the fuse holding groove 30a is engaged in a lead engagement groove 31b. Further, the connection portion 29 is press-fitted with a terminal 34 for electrically connecting the cut ends 27 a and 27 b of the excitation coil 27 and the lead 33 b of the thermal fuse 33.

As shown in FIG.
Is a pair of side plates 34a which are bent in a U-shape and face each other,
34b are formed. Each side plate 34a, 34b has
A groove 34c having a groove width for breaking the insulating coating of the cut ends 27a and 27b of the exciting coil 27 and biting into the core wire, and a groove 34d having a groove width capable of electrically connecting to the lead 33b of the thermal fuse 33 are formed. ing. In addition, each side plate 34
Locking claws 34e are formed on the end surfaces of the a and 34b so as to bite into the wall surface of the groove 31c when pressed into the groove 31c for terminal engagement. Accordingly, the side plates 34a, 34b of the terminal 34 are engaged with the terminal engaging groove 31c while the cut ends 27a, 27b are pressed into the groove 34c and the leads 33b are pressed into the groove 34d, thereby exciting the terminal 34. Coil 27
And the thermal fuse 33 are connected in series. Terminal 3
The fourth engaging claw 34e bites into the wall surface of the terminal engaging groove 31c.

The exciting coil 27 to which the thermal fuse 33 is connected has a plurality of caulking pieces 23d formed by caulking the inner and outer extreme surfaces 23b and 23c of the yoke 23.
, And is held in the coil receiving groove 23a of the yoke 23. The connection portion 29 of the coil cover 26 is provided with a colorless and transparent ultraviolet-curable and moisture-curable silicone resin (ThreeBond (registered trademark) 316 manufactured by ThreeBond Co., Ltd.).
1, hereinafter referred to as silicone resin) to form a resin coating layer 35.

The casting (filling and curing) operation of the silicone resin is performed in the final step of the assembling step of the yoke assembly, and the main steps include a preheating step, a temporary filling step, a main filling step, a bubble removing step, and an ultraviolet ray. There is an irradiation step. In the preheating step, hot air is blown to the yoke assembly in which the connection portion 29 is not filled with the resin, and the connection portion 29 is heated. In the preheating step, in the filling step, the groove 31a for engaging the cut end, the groove 31b for engaging the lead, the groove 31c for engaging the terminal, and the gap between the case 33a of the thermal fuse 33 and the holding groove 30a are formed. This is a process for improving the fluidity of the silicone resin so that the silicone resin flows into the narrow gaps well.

The temporary filling step is a step of filling the pre-heated connection portion 29 with an appropriate amount of silicone resin, and is a step of bleeding a narrow gap by pouring the silicone resin and causing air to appear as bubbles. That is, if the connection portion 29 is filled with the silicone resin at a time, air bubbles remain inside the resin, and when the silicone resin is cured in this state, the air bubbles burst and the case 33a of the thermal fuse 33 is exposed.

The main filling step is a step of filling an appropriate amount of silicone resin into the connection portion 29 from which air has been removed in the temporary filling step until the case 33a of the thermal fuse 33 is hidden.

The bubble removing step is a step of removing bubbles that have appeared on the resin surface by blowing a breeze.

The ultraviolet irradiation step is a step of irradiating the silicone resin filled in the connection portion 29 with ultraviolet rays emitted from an ultraviolet irradiation lamp for about 1.5 minutes, thereby photochemically changing the silicone resin and curing the silicone resin. Although there is a shadow portion in the connection portion 29 where ultraviolet rays are not irradiated, the silicone resin of the embodiment has a property of curing even with moisture, and sufficient hardness can be obtained by leaving the yoke assembly for several hours.

In the yoke assembly in which the thermal fuse 33 is protected from the outside by the resin coating layer 35 by such a resin casting operation, the mounting plate 24 is fitted to the nose portion 9c and fixed to the side surface of the housing 9b. To the compressor 9. The rotor 14 is rotatably supported by the compressor 9 by fitting the bearing 13 fitted to the inner cylindrical portion 14a to the nose portion 9c. Still further, the armature assembly is configured such that the boss 15a of the hub 15 is
a, and the bolt 12 is screwed into a screw hole of the rotating shaft 9a in a state where the backing plate 11 is abutted against the rotating shaft 9a, thereby being integrally mounted on the rotating shaft 9a. The electromagnetic clutch 10 mounted on the compressor 9 is
A belt (not shown) is mounted on the belt groove 22 of the rotor 14 mounted on the vehicle.

The electromagnetic clutch 10 mounted on the vehicle turns on the armature 21 by energizing the exciting coil 27.
Is magnetically attracted to the rotor 14 against the elastic return force of the damper rubber 19, so that power is transmitted to the compressor 9. In addition, during energization of the electromagnetic coil 27, when the rotary shaft 9a is locked due to a failure of the compressor 9, the armature 21 and the rotor 14 slip and rotate, generating frictional heat. Accordingly, the temperature around the temperature fuse 33 is also increased, and the temperature fuse 33 is blown. Therefore, the power supply to the exciting coil 27 is cut off, and the power transmission to the compressor 9 is cut off.

As described above, the embodiment of the present invention has been described with respect to the electromagnetic clutch mounted on the refrigerant compressor for an automobile. However, the present invention is also applied to an electromagnetic clutch disposed on a power transmission path other than a vehicle. be able to. Further, although the coil bobbin is constituted by the bobbin main body and the coil cover, the shape and configuration of the coil bobbin are not limited to those described in the embodiment.

[0037]

According to the electromagnetic clutch of the first invention, the work of covering and fixing the connection portion of the coil bobbin with the fuse cover can be omitted. In addition, the peripheral wall of the connection portion can be made higher because the fuse cover is not required, and a temperature fuse having a large outer diameter of the case can be employed. Furthermore, compared to the case where a thermal fuse is provided in a connection portion closed by a fuse cover, the ultraviolet-curable and moisture-curable silicone resin has better heat conductivity, and thus has a responsiveness and operational reliability of the thermal fuse. Is improved. In addition, since a resin that is cured by ultraviolet irradiation and moisture is employed, the operation is easier than a casting (filling and curing) operation of a thermosetting resin such as an epoxy resin, and the productivity of the electromagnetic clutch is improved.

The electromagnetic clutch according to the second aspect of the present invention can prevent casting defects such as bubbles remaining inside the filled resin and bursting when cured. Therefore, the connection between the excitation coil and the thermal fuse can be reliably protected.

In the electromagnetic clutch according to the third aspect of the present invention, the cut end of the exciting coil is guided from the leading end side of the lead of the thermal fuse to the groove for engaging the coil, so that the space of the fuse holding portion can be effectively used. A thermal fuse having a large outer diameter can also be employed.

The electromagnetic clutch according to the fourth aspect of the present invention can increase the strength of the vicinity of the outlet of the coil drawing hole, and can prevent breakage around the outlet when the cut end is drawn. Therefore, it is possible to prevent a casting failure in which the resin before curing filled in the connection portion leaks from the damaged coil extraction hole to the exciting coil side.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electromagnetic clutch shown as an embodiment of the present invention.

FIG. 2 is a plan view of the exciting device of FIG. 1;

FIG. 3 omitting a casting resin, a thermal fuse, and terminals;
FIG.

FIG. 4 is a plan view of a main part of FIG. 2 from which a casting resin and terminals are omitted.

FIG. 5 is a plan view of a main part of FIG. 2;

6 (a) is a bottom view, and FIG. 6 (b) is a side view. FIG.

FIG. 7 is a sectional view taken along the line BB of FIG. 3 illustrating only a coil cover.

FIG. 8 is a sectional view taken along line CC of FIG. 3 illustrating only a coil cover.

FIG. 9 is a sectional view taken along line DD of FIG. 3 illustrating only a coil cover.

FIG. 10 is a sectional view taken along line EE of FIG. 3 illustrating only a coil cover.

FIG. 11 is a sectional view taken along line FF of FIG. 3 illustrating only a coil cover.

FIG. 12 is a plan view of only a main part of a conventional yoke.

FIG. 13 is a plan view of only a main part of a conventional coil cover.

FIG. 14 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 Reference Signs List 23 Yoke 25 Bobbin main body 26 Coil cover 27 Exciting coil 27a Cutting end 27b Cutting end 30 Fuse holding unit 30a Holding groove 31 Terminal press-fitting unit 31a Cutting end engaging groove 31b Lead engaging groove 31c Terminal engaging Groove 32 Coil lead-out part 32a Coil lead-out hole 32b Insertion port 32c Peripheral wall 32d Outlet 33 Thermal fuse 33a Case 33b Lead 34 Terminal 35 Resin coating layer

Claims (4)

[Claims] 1. A yoke in which an exciting coil held by a coil bobbin is accommodated in a coil accommodating groove, and a cut end of the exciting coil drawn out while being surrounded by a peripheral wall protruding from a side surface and opening in the same direction as the coil accommodating groove. An electromagnetic clutch, comprising: a connection portion of the coil bobbin in which a portion and a lead of a thermal fuse are connected by a terminal, and the connection portion is filled with an ultraviolet curable and moisture curable silicone resin. 2. A heated and hardened connection portion of the coil bobbin is filled with an appropriate amount of an ultraviolet-curable and moisture-curable silicone resin in several portions, and the ultraviolet light is removed by removing air bubbles that have appeared on the surface of the resin by a breeze. The electromagnetic clutch according to claim 1, wherein the resin filled in the connection portion is cured by irradiating and leaving the resin. 3. A connection portion of the coil bobbin has a holding portion formed with a holding groove for holding a case of a thermal fuse at a bottom portion, a groove extending in parallel extending for engaging a lead, and an engaging portion for engaging a cut end. And a terminal press-fitting portion formed with a groove for terminal engagement orthogonal to these grooves and provided on both sides in the longitudinal direction of the holding groove, and provided on the opposite side of each terminal press-fitting portion to the fuse holding portion. A coil extraction portion provided with a coil extraction hole from which a cut end of the excitation coil is extracted,
3. The electromagnetic clutch according to claim 1, wherein a cut end of the exciting coil is bent toward the terminal press-fitting portion and is engaged with the cut end engaging groove. 4. The electromagnetic clutch according to claim 3, wherein an outlet defined by a peripheral wall protruding from the bottom of the coil outlet is formed in the coil outlet.