Electromagnetic coil and electromagnetic clutch including the same

Abstract

To ensure that insulation between a coil and a coil case is reliably maintained even when the coil is housed in the coil case without performing an additional coating process after a connection process for connecting external wiring, etc.SOLUTION: An electromagnetic coil 10 includes a magnetic coil case 11 having a ring-shaped storage groove 16, a coil 12 directly housed in the storage groove 16, a covering body 13 covering the entire coil 12, an insulating layer 14 composed of an electrically insulating thermosetting resin impregnated into the covering body 13, that at least covers the surface of the coil 12, and a wiring connection part 17 to which external wiring 20 supplying power to the coil 12 is connected. An insulating member 15 is provided between the wiring connection part 17 and the coil case 11.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electromagnetic coil used in an electromagnetic clutch or the like, and an electromagnetic clutch provided with this electromagnetic coil.

Background Art

[0002] It has been proposed to abolish the coil bobbin to reduce the size and weight of the electromagnetic coil. Such a bobbinless electromagnetic coil needs to be electrically insulated between the side wall of the storage groove of the coil case and the coil without passing through the coil bobbin. Therefore, it has been considered to manufacture the electromagnetic coil by the following manufacturing process.

[0003] That is, the coil winding is wound around a winding jig by a winding machine to manufacture a bobbinless coil (winding process), The manufactured bobbinless coil is removed from the winding jig and held in a coil state by a temporary fixing tape (holding process), A connection end portion for connecting to an external wiring and a component connection portion for connecting an accessory component as necessary are drawn out from the bobbinless coil (connection preparation process), Except for the connection end portion 100a and the component connection portion 100b, the entire bobbinless coil 100 is covered with a covering body 101 (covering process, see Fig. 13(a)), The bobbinless coil is connected to an external wiring 102 at the connection end portion 100a and an accessory component 103 is connected to the component connection portion 100b (connection process, see Fig. 13(b)), The connection end portion 100a to which the external wiring 102 is connected and the component connection portion 100b to which the accessory component 103 is connected are covered with an additional covering body 101a (additional covering process, see Fig. 13(c)), The coil 100 covered with the covering bodies 101 and 101a in the covering process and the additional covering process is accommodated in the accommodation groove 111 of the coil case 110 (accommodation process), The liquid thermosetting resin and the coil case 110 are preheated (preheating process), The liquid thermosetting resin 112 is injected into the storage groove 111 and impregnated into the coatings 101, 101a (impregnation process, see Fig. 13(d)). The liquid thermosetting resin impregnated into the coatings 101, 101a is heated and cured to form the electrical insulation layer 113 (curing process). A series of steps are performed. As a result, an electromagnetic coil electrically insulated between the coil case 110 and the coil 100 was manufactured.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described steps, in the connection step, the external wiring 102 and the accessory parts 103 (such as a thermal fuse and a diode) are connected to the connection end portion 100a and the component connection portion 100b of the coil 100 outside the coating 101 wound around the coil. In order to avoid a short circuit with the coil case 110, after the connection step, an additional coating step is further provided, and the coating 101a is manually added to the exposed connection portion. For this reason, the process becomes complicated, and if the state of the coating by manual work is poor, there is a risk of short circuit.

[0005] Therefore, while aiming to reduce costs by simplifying the work, reliable insulation measures inside the coil case are required.

[0006] The present invention has been made in view of such circumstances, and an electromagnetic coil capable of surely ensuring insulation from the coil case without performing an additional coating step after the connection step, and an electromagnetic clutch provided with such an electromagnetic coil are the main problems.

Means for Solving the Problems

[0007] To achieve the above object, the electromagnetic coil according to the present invention has a magnetic coil case (11) having an annular storage groove (16), The coil (12) directly accommodated in the accommodation groove (16), A covering (13) having stretchability and resin impregnability and covering the entire coil (12), An electrical insulation layer (14) formed of an electrically insulating thermosetting resin impregnated in the covering (13) and covering the surface of the coil (12), A wiring connection part (17) through which an external wiring (20) that is inserted through the through hole (23) of the coil case (11) and supplies power to the coil (12) is connected, In the electromagnetic coil (10) provided with, It is characterized by including an insulating member (15) between the wiring connection part (17) and the coil case (11).

[0008] Therefore, when accommodating the coil in the coil case after the connection step of connecting the external wiring to the wiring connection part, since it is accommodated with an insulating member interposed between the wiring connection part and the coil case, insulation is surely ensured between the wiring connection part and the coil case. For this reason, the work of additionally covering the wiring connection part becomes unnecessary.

[0009] Here, the insulating member is preferably formed of a plate-like member made of an electrically insulating material.

[0010] Since the insulating member is arranged between the inner surface of the annular coil case and the wiring connection part, using a plate-like member makes it easy to arrange it along the inner surface of the coil case or the outer surface of the coil.

[0011] However, when the electromagnetic coil generates heat when energized and is used in an electromagnetic clutch, the frictional heat in the clutch is transmitted, so durability of 150°C or higher is required. For this reason, the insulating member is preferably formed of an insulating material (for example, PP, PA, PA66, Melinex 238, etc.) having heat resistance with a melting point temperature of 150°C or higher.

[0012] The insulating member (15) formed of a plate-like member may be composed of, for example, an inner peripheral side wall (15a), an outer peripheral side wall (15b), and a bottom wall (15c) connecting the ends of these side walls (15a, 15b).

[0013] According to such a configuration, the insulating member can surely prevent a short circuit with respect to the inner peripheral wall and the outer peripheral wall of the storage groove of the coil case.

[0014] The insulating member (15) may be provided with a wiring insertion portion (15d) through which the external wiring (20) is inserted. Here, the wiring insertion portion is not particularly limited as long as it has a shape that allows the external wiring to be inserted through the insulating member, and may be a groove-shaped one (insertion groove) or an insertion hole.

[0015] According to such a configuration, since the insulating member is provided with a wiring insertion portion through which the external wiring is inserted, it is possible to position the insulating member by the external wiring, prevent displacement of the insulating member, and surely prevent a short circuit of the wiring connection portion.

[0016] Further, the insulating member (15) may be configured such that the lengths on both sides in the circumferential direction are equal with the wiring insertion portion (15d) as the center.

[0017] According to such an insulating member, the insulating member can surely cover the wiring connection portions arranged at equal positions on both sides in the circumferential direction from the wiring insertion portion.

[0018] In the electromagnetic coil (10) in which the coil (12) has one end face (120a) provided with the wiring connection portion (17) for connecting the external wiring (20), and the other end face (120b) provided with a temperature fuse (25) and provided on the opening end side of the coil case (11), and a cross wire (27) for electrically connecting the temperature fuse (25) and the wiring connection portion (17) is disposed on the radially outer side of the coil (12), the insulating member (15) may also be disposed between the cross wire (27) and the coil case (11).

[0019] In particular, in the accommodation groove of the coil case where the width on the bottom wall side is narrower than the width on the opening side, when the coil is accommodated in the accommodation groove, the coil and the side wall of the coil case are close to each other on the bottom wall side. Further, when the lead wire is exposed on the side surface of the coil, the lead wire is likely to come into contact with the coil case on the side close to the bottom wall, and there is a concern of a short circuit. Therefore, by arranging the insulating member also between the lead wire and the coil case, it is possible to reliably prevent a short circuit regardless of the shape of the coil case.

[0020] Furthermore, even when the connection end portion (12b) of the coil (12) connected to the temperature fuse (25) is disposed on the radially outer side of the coil (12), the insulating member (15) may be arranged also between the connection end portion (12b) of the coil (12) and the coil case (11).

[0021] In such a configuration, since the insulating member is also arranged between the connection end portion of the coil and the coil case, it is possible to reliably prevent a short circuit. In such a configuration, since it is also assumed that the connection end portion of the coil is disposed at a position away from the external wiring, the insulating member may have different lengths on both sides in the circumferential direction with the wiring insertion portion (15d) as the center.

[0022] Also, the insulating member may be provided over the entire circumference of the accommodation groove of the coil case, or the heights of the inner peripheral side wall and the outer peripheral side wall may be made equal, or the height of the inner peripheral side wall may be made higher than the height of the outer peripheral side wall.

Advantages of the Invention

[0023] As described above, according to the present invention, in the electromagnetic coil, since the insulating member is provided between the wiring connection portion to which the external wiring for supplying power to the coil is connected and the coil case, the step of applying an additional coating with a covering body to insulate the wiring connection portion becomes unnecessary, and the manufacturing process can be simplified and the cost can be reduced.

[0024] In addition, since the operation of applying an additional insulation coating is eliminated, the inconvenience of the insulation state being difficult to be ensured due to variations in the state of the additional coating is also eliminated, and reliable insulation between the coil case can be ensured.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the forms shown in the accompanying drawings are examples of the present invention, and the present invention is not limited to these forms.

[0027] First, an electromagnetic clutch 1 provided with an electromagnetic coil according to the present invention will be described.

[0028] As shown in FIG. 1, the electromagnetic clutch 1 includes an electromagnetic coil 10 described later, a driving-side rotor 2 made of a magnetic material, a driven-side hub 3 that can rotate relative to the rotor 2, and an armature plate 4 made of a magnetic material and connected to the hub 3 and disposed opposite to the side end surface of the rotor 2 with a gap therebetween.

[0029] The electromagnetic coil 10 is fixed to a housing 5 (for example, the housing of a compressor) via a fixing plate 8 and is housed inside the rotor 2. When the electromagnetic coil 10 is energized, it forms a magnetic circuit passing through the rotor 2 and the armature plate 4, and magnetically attracts the armature plate 4 to the rotor 2.

[0030] The hub 3 is attached to a rotating shaft 6 protruding outward from the housing 5 with relative rotation restricted.

[0031] Further, the rotor 2 is an annular member centered on the center line CL of the rotary shaft 6, and is constituted by, for example, a pulley to which rotational power is transmitted via a belt from an external power source such as an engine. The rotor 2 is rotatably supported with respect to the boss portion 5a of the housing 5 via a radial bearing 7.

[0032] The armature plate 4 is made of a magnetic material, is fixed to the hub 3 via an elastic member, and is disposed opposite to the side end face of the rotor 2 with a gap therebetween. A friction surface 4a facing the side end face of the rotor 2 is formed on the armature plate 4. The friction surface 4a can be engaged with the side end face of the rotor 2 by electromagnetic attraction due to the deformation of the elastic member.

[0033] Therefore, when the electromagnetic coil 10 is energized while the rotor 2 is belt-driven by an external power source, the armature plate 4 is electromagnetically attracted (engaged) to the rotor 2 and rotates together with the rotor 2, and the rotary shaft 6 rotates via the hub 3 integral with the armature plate 4.

[0034] The electromagnetic coil 10 is fixed to a fixing plate 8 attached to the housing 5 and is housed while securing a predetermined clearance from the rotor 2 (pulley). That is, an annular housing recess 21 that opens to the end face opposite to the end face facing the armature plate 4 is formed in the rotor 2 centered on the center line CL. The electromagnetic coil 10 is fixed to the fixing plate 8 disposed so as to face the opening end of the housing recess 21, and is inserted into the housing recess 21 so that a gap is formed between the electromagnetic coil 10 and the inner wall of the housing recess 21. Therefore, the rotor 2 can rotate without contacting the electromagnetic coil 10.

[0035] As shown in Fig. 2, the electromagnetic coil 10 is formed in an annular shape centered on the center line CL of the rotating shaft 6, and includes an annular coil case 11, a coil 12 housed in the coil case 11, a coating 13 that has elasticity and resin impregnation property and covers the entire coil 12, an electrical insulation layer 14 formed of a thermosetting resin that is impregnated into the coating 13 and injected into the coil case 11, and an insulating member 15 interposed between the coil 12 and the coil case 11.

[0036] The coil case 11 is formed in a U-shaped cross section with an open end on the side opposite to the fixed plate 8, and includes an inner peripheral side wall 11a, an outer peripheral side wall 11b, and a bottom wall 11c that connects the ends of these side walls 11a and 11b to close the end on the fixed plate 8 side. An annular storage groove 16 is defined by the side walls 11a, 11b and the bottom wall 11c.

[0037] The groove width of the storage groove 16 is formed widest at the open end portion on the side opposite to the bottom wall 11c, and gradually narrows toward the bottom wall 11c. Further, a through hole 23 into which a grommet 22 for inserting the external wiring 20 can be attached is provided at a predetermined position of the bottom wall 11c. This through hole 23 is provided at a position aligned with the through hole 81 provided in the fixed plate 8, and the end portion of the grommet 22 protruding from the coil case 11 can be inserted into the through hole 81.

[0038] The coil 12 is directly stored in the storage groove 16 of the coil case 11 without passing through a coil bobbin. Such a coil 12 is sometimes called a bobbinless coil.

[0039] This coil (bobbinless coil) 12 is composed of a coil winding wire such as a copper wire, and the cross-sectional shape of the coil is formed in a square shape corresponding to the shape of the storage groove 16 of the coil case 11.

[0040] As described above, the covering 13 is composed of a member having stretchability and resin impregnation properties. For example, a tape-like member made of a stretchable non-woven fabric that can be wound around the coil 12 is used. By winding the covering 13 around the coil 12 (by multi-winding), the thickness of the covering 13 can be adjusted, and it becomes possible to control the thickness of the liquid thermosetting resin impregnated in the covering 13, in other words, the thickness of the electrical insulation layer 14.

[0041] The insulating member 15 is formed in a plate shape from an electrical insulating material. This insulating member 15 is at least disposed between the insertion end portion 120a of the coil 12 inserted into the storage groove 16 of the coil case 11 and the coil case 11.

[0042] That is, the insulating member 15 is disposed between the insertion end portion 120a of the coil 12 into the storage groove 16 and the bottom wall 11c of the coil case 11, and is provided so as to insulate the wiring connection portion 17 connected to the external wiring 20 from the coil case 11. As shown in FIG. 3, the insulating member 15 in this example is composed of an inner peripheral side wall 15a, an outer peripheral side wall 15b, and a bottom wall 15c that connects the ends of these side walls 15a and 15b.

[0043] The inner peripheral side wall 15a is curved along the inner peripheral side wall 11a of the coil case 11 over a range of a predetermined central angle. Also, the outer peripheral side wall 15b is curved along the outer peripheral side wall 11b of the coil case 11 over the same range of the central angle as the inner peripheral side wall 15a.

[0044] Further, a wiring insertion portion 15d for inserting the external wiring 20 is formed in a substantially central portion in the circumferential direction on the bottom wall 15c of the insulating member 15. In this example, the wiring insertion portion 15d is configured by forming a wiring insertion groove extending in the circumferential direction on the bottom wall 15c by cutting out the central portion of the inner peripheral side wall 15a. Therefore, the insulating member 15 extends the same length on both sides in the circumferential direction with the wiring insertion portion 15d as a boundary.

[0045] Further, the height β (length from the bottom wall 15c) of the outer peripheral side wall 15b is formed higher than the height α (length from the bottom wall 15c) of the inner peripheral side wall 15a. In this example, the outer peripheral side wall 15b is set to a height that can cover up to approximately half of the length along the center line CL of the outer peripheral surface of the coil 12.

[0046] As also shown in FIG. 4, a temperature fuse 25 that shuts off the circuit when the electromagnetic clutch 1 is abnormally hot, and a diode 26 that prevents a large surge voltage from being generated due to the back electromotive force generated when shutting off the current flowing through the coil 12 are connected to the coil 12 as needed.

[0047] The external wiring 20 that is directly connected to the connection end portions 12a and 12b of the coil 12 or indirectly connected via the temperature fuse 25 to supply power to the coil 12 is inserted through the through hole 23 of the coil case 11 and connected to the wiring connection portion 17 disposed between the coil 12 and the coil case 11. On the other hand, the temperature fuse 25 is attached to a portion close to the end face of the rotor 2 to which the armature plate 4 is attracted, that is, the end face 120b opposite to the end face 120a where the wiring connection portion 17 for connecting the external wiring 20 is provided, in order to detect an abnormal temperature without delay. Here, the coil surface where the wiring connection portion 17 of the coil 12 is disposed is sometimes referred to as the coil lower surface 120a, and the coil surface where the temperature fuse 25 is disposed is sometimes referred to as the coil upper surface 120b.

[0048] Therefore, one connection end portion 12a of the coil 12, one external wiring 20a, and one end portion 26a of the diode 26 are connected by a wiring connection portion 17a. The other connection end portion 12b of the coil 12 routed from the lower coil surface 120a to the upper coil surface 120b and one end portion 25a of the thermal fuse 25 are connected by a component connection portion 30a. The other end portion 25b of the thermal fuse 25 and one end portion 27a of the jumper wire 27 routed from the upper coil surface 120b to the lower coil surface 120a are connected by a component connection portion 30b. The other end portion 27b of the jumper wire 27, the other external wiring 20b, and the other end portion 26b of the diode 26 are connected by a wiring connection portion 17b.

[0049] At this time, for reasons of workability, the other connection end portion 12b of the coil 12 and the jumper wire 27 are routed along the side surface on the outer peripheral side of the coil 12 between the lower coil surface 120a and the upper coil surface 120b as shown in FIGS. 5 and 6. The storage groove 16 of the coil case 11 is formed to be narrower toward the bottom wall 11c, and the distance between the coil 12 and the coil case 11 becomes smaller as it approaches the bottom wall 11c. In this example, the length (height) of the outer peripheral side wall 15b of the insulating member 15 is provided higher than the length (height) of the inner peripheral side wall 15a. In the lower half portion where the other connection end portion 12b of the coil 12 and the jumper wire 27 are likely to approach the coil case 11, the outer peripheral side wall 15b can bring the connection end portion 12b and the jumper wire 27 closer to the coil side. Thereby, after reliably separating the connection end portion 12b and the jumper wire 27 from the coil case 11, the insulating member 15 insulates from the coil case 11.

[0050] Then, as shown in FIG. 7, the above-described insulating member 15 is attached to the coil 12 covered with the covering body 13 in a state where the external wiring 20 connected to the wiring connection portion 17 is drawn out through the wiring insertion portion 15d. Then, as shown in FIG. 10, the coil 12 in that state is stored in the storage groove 16 of the coil case 11. Thereafter, the coil 12 stored in the storage groove 16 is injected with a thermosetting resin that constitutes the electrical insulating layer 14. As a result, the coil 12 and the insulating member 15 are fixed to the coil case 11.

[0051] The coil 12 equipped with the thermal fuse 25 is fixed to the coil 12 by injecting the thermosetting resin so that the thermosetting resin adheres to the thermal fuse 25 and the component connection parts 30a and 30b when injecting the thermosetting resin.

[0052] Next, a method for manufacturing the electromagnetic coil 10 using the above insulating member 15 will be described.

[0053] The manufacturing method of the electromagnetic coil 10 in this example is the same as the conventional method up to the connection process of connecting the external wiring 20.

[0054] That is, as shown in FIG. 8(a), the coil winding 121 is wound around the winding jig 51 by a winding machine (not shown), and the coil (bobbinless coil) 12 is manufactured (winding process).

[0055] Thereafter, as shown in FIG. 8(b), the coil (bobbinless coil) 12 is removed from the winding jig 51 and the coil state is held by the temporary fixing tape 52 (holding process).

[0056] After this holding process, as shown in FIG. 8(c), the connection end parts 12a and 12b connected to the external wiring 20 and the thermal fuse 25 are pulled out from the coil 12 (component connection preparation process).

[0057] After this component connection preparation process, as shown in FIG. 9(a), except for the connection end parts 12a and 12b, the entire coil 12 is covered with the covering body 13 (covering process). This covering process is performed, for example, by winding the tape-shaped covering body 13 around the coil 12 by a winding machine (not shown). By this covering process, the coil 12 can be electrically insulated between the connection end parts 12a and 12b and the coil case 11.

[0058] After this coating process, as shown in Fig. 9(b), for the coil 12, one end 26a of the external wiring 20a or the diode 26 is connected to the connection end 12a by the wiring connection part 17a, and one end 25a of the thermal fuse 25 is connected to the connection end 12b by the component connection part 30a. Further, the other end 25b of the thermal fuse 25 is connected to one end 27a of the jumper wire 27 by the component connection part 30b. The other end 27b of the jumper wire 27 is connected to the other end 26b of the external wiring 20b or the diode 26 by the wiring connection part 17b.

[0059] The wiring connection parts 17a and 17b only need to be able to make electrical connections with each conductor and component, and are connected by crimp sleeves, welding, or soldering. The component connection parts 30a and 30b are also connected by crimp sleeves, welding, or soldering.

[0060] After this connection process, conventionally, the coil 12 would undergo an additional coating process in which the wiring connection parts 17a and 17b, the diode 26, and the jumper wire 27 that are exposed from the coating 13 are coated with an additional coating. However, here, no additional coating by the coating is performed. The wiring connection parts 17a and 17b, the diode 26, and the jumper wire 27 are covered by the insulating member 15 (see Fig. 5). Further, as shown in Figs. 6 and 7, after the external wiring 20 is drawn out from the wiring insertion part 15d, the insulating member 15 is attached to the lower coil surface 120a side of the coil 12 with the coating 13 wound over the wiring connection parts 17a and 17b, the diode 26, and the jumper wire 27 (insulating member attachment process).

[0061] Note that since the wiring connection parts 17a and 17b, the diode 26, and the jumper wire 27 protrude from the coating 13, a gap is formed between the insulating member 15 and the coating 13.

[0062] After this insulating member mounting step, as shown in Fig. 10(a), the coil 12 with the insulating member 15 mounted thereon is stored in the storage groove 16 of the coil case 11 from the side of the insulating member 15 (storage step). At this time, the grommet 22 is passed through the external wiring 20, and the external wiring 20 and the grommet 22 are inserted into the through holes 23 and 81 of the coil case 11, and the grommet 22 is fitted into the through hole 23. Note that in this storage step, the coil case 11 is pre-set in a case holding jig (not shown) in a state where the fixing plate 8 is previously fixed to the bottom wall 11c. In this set state, the coil case 11 is fixed with the fixing plate 8 facing down and the open end of the storage groove 16 facing upward.

[0063] By this storage step, as shown in Fig. 10(b), the coil 12 is stored in the storage groove 16 together with the insulating member 15 (storage step). Note that as shown in the figure, the outer shape of the insulating member 15 does not have to match the shape of the storage groove 16, and a gap may be formed between the bottom wall 15c of the insulating member 15 and the bottom wall 11c of the coil case 11.

[0064] After this storage step, in order to maintain the fluidity of the liquid thermosetting resin 70 having electrical insulation properties, the thermosetting resin 70 and the coil case 11 are preheated (preheating step). Then, after this preheating step, as shown in Fig. 10(c), the liquid thermosetting resin 70 is injected into the storage groove 16, so that the liquid thermosetting resin 70 is impregnated into the covering 13, and all the gaps between the coil 12 and the coil case 11, between the coil 12 and the insulating member 15, and between the insulating member 15 and the coil case 11 are filled with the thermosetting resin (resin injection step). At this time, the liquid thermosetting resin 70 supplied into the coil case 11 may be taken in a fixed amount preset in the container 81, preheated by the heater 82, and poured into the storage groove 16. After the resin is injected and a certain time elapses, the liquid thermosetting resin 70 uniformly impregnates the covering 13.

[0065] After the resin injection process, the poured liquid thermosetting resin 70 is heated and cured to form the electrical insulation layer 14 (curing process). For example, the coil case 11 after the resin injection process is placed in a curing furnace and heated, causing the liquid thermosetting resin 70 to cure.

[0066] After this curing process, the coil case 11 is cooled to room temperature, and a series of processes for manufacturing the electromagnetic coil 10 is completed.

[0067] Therefore, according to the above-described electromagnetic coil, since the insulating member 15 is provided at least between the wiring connection portions 17a and 17b to which the external wiring is connected and the coil case 11, it is possible to ensure insulation reliably without additionally coating the wiring connection portions 17a and 17b.

[0068] In particular, the wiring connection portion 17 to which the external wiring 20 of the coil 12 is connected is difficult to visually confirm the filling state of the thermosetting resin when the coil 12 is housed in the coil case 11. However, by interposing the insulating member 15, even if the formation of the electrical insulation layer 14 is insufficient, it is possible to surely ensure insulation between the coil 12 and the coil case 11.

[0069] Further, the insulating member 15 includes not only the bottom wall 15c but also the inner peripheral side wall 15a and the outer peripheral side wall 15b, and insulates between the corresponding wall surfaces of the coil case 11. Therefore, even when the positions of the wiring connection portions 17a and 17b and the jumper wire 27 are displaced when the coil 12 is housed in the housing groove 16, it is possible to surely ensure insulation between the coil case 11.

[0070] Further, since the insulating member 15 makes the length (height) of the outer peripheral side wall 15b higher than the length (height) of the inner peripheral wall side wall 15a, the jumper wire 27 is brought closer to the coil side by the insulating member in the lower half portion where the jumper wire 27 is likely to approach the coil case 11, so that it is possible to surely insulate between the jumper wire 27 and the coil case 11.

[0071] Furthermore, in this embodiment, since the wiring insertion portion of the insulating member is formed in the center and insulating regions of equal length are provided on both sides (since the circumferential lengths of the side walls and the bottom wall are made equal on the left and right), it is possible to insulate a portion where wiring connection portions tend to concentrate with the insulating member 15 having a length without excess or deficiency. That is, since the insulating member 15 is formed such that the circumferential length is equal on the left and right with the wiring insertion portion 15d as the center, when connection end portions are provided at equal positions from the wiring insertion portion 15d, the insulating member 15 can avoid the inconvenience that the circumferential length is too short to maintain insulation and the inconvenience that the circumferential length is too long and there are many useless portions that do not contribute to insulation.

[0072] In addition, in the above-described configuration, as shown in FIGS. 5 to 7, an example is shown in which the wiring connection portions 17a and 17b to which external wiring is connected are covered by the symmetric insulating members 15. However, when the temperature fuse 25 is provided on the opening end side of the coil case 11, conductors that connect between the opening end side and the bottom wall side of the coil case along the outer peripheral surface of the coil 12 protrude from both ends of the temperature fuse 25. The bridging wire 27 corresponds to one of the conductors, but the two conductors are not necessarily arranged at positions symmetric with respect to the wiring insertion portion 15d. Therefore, in such a case, as shown in FIG. 11, the insulating member 15 may be formed in an asymmetric shape in which the circumferential length on one side with respect to the wiring insertion portion 15d is longer than the circumferential length on the other side, so as to ensure insulation between the conductors connected to both ends of the temperature fuse and the coil case 11.

[0073] In the above example, the side wall 15b on the outer peripheral side of the insulating member 15 is made longer than the side wall 15a on the inner peripheral side, so as to ensure reliable insulation between the conducting wire (the connecting wire 27, the other connecting end portion 12b of the coil 12) connecting the opening end side and the bottom wall side of the coil case 11 on the outer peripheral side and the coil case 11. However, the shape is not limited to this, and the side wall 15a of the inner peripheral wall may be set to the same height as the side wall 15b of the outer peripheral wall. Also, the height of the side wall may be set to a height that covers the entire height (axial length) of the coil 12. Further, the side walls 15a and 15b may be provided over the entire circumference of the storage groove 16. For example, an insulating member 15 (both the side wall 15a of the inner peripheral wall and the side wall 15b of the outer peripheral wall) as shown in FIG. 12 may be used, which has a height that covers the entire height (axial length) of the coil 12 and is formed in an annular shape over the entire circumference of the storage groove 16.

[0074] Furthermore, in the above example, the wiring insertion portion 15d is shown as being constituted by an insertion groove for inserting the external wiring 20, but it may also be constituted by a through hole provided in the bottom wall 15c of the insulating member 15.

Explanation of Reference Numerals

[0075] 1 Electromagnetic clutch 10 Electromagnetic coil 11 Coil case 12 Coil 12a, 12b Connection end portions 13 Coating 14 Electric insulating layer 15 Insulating member 15a Side wall on the inner peripheral side 15b Side wall on the outer peripheral side 15c Bottom wall 15d Wiring insertion portion 16 Storage groove 17, 17a, 17b Wiring connection portions 20 External wiring 23 Through hole 25 Thermal fuse 27 Connecting wire

Claims

1. A magnetic coil case (11) having an annular storage groove (16), A coil (12) directly stored in the storage groove (16), A coating (13) having stretchability and resin impregnability and covering the entire coil (12), An electrical insulation layer (14) formed of an electrically insulating thermosetting resin impregnated in the coating (13) and covering at least the surface of the coil (12), A wiring connection portion (17) through which an external wiring (20) for supplying power to the coil (12) is connected by inserting through a through hole (23) of the coil case (11), In an electromagnetic coil (10) provided with, An electromagnetic coil characterized in that an insulating member (15) is provided between the wiring connection portion (17) and the coil case (11).

2. The electromagnetic coil according to claim 1, wherein the insulating member (15) is a plate-like member formed of an electrically insulating material.

3. The electromagnetic coil according to claim 1, wherein the insulating member (15) is composed of an inner peripheral side wall (15a), an outer peripheral side wall (15b), and a bottom wall (15c) connecting ends of these side walls (15a, 15b).

4. The electromagnetic coil according to claim 1, wherein the insulating member (15) includes a wiring insertion portion (15d) through which the external wiring (20) is inserted.

5. The electromagnetic coil according to claim 4, wherein the insulating member (15) has equal lengths on both sides in the circumferential direction with the wiring insertion portion (15d) as the center.

6. The coil 12 has one end face (120a) provided with the wiring connection portion 17 for connecting the external wiring (20), and the other end face (120b) provided with a temperature fuse (25) and provided on the opening end side of the coil case (11). In an electromagnetic coil (10) in which a connecting wire (27) for electrically connecting the temperature fuse (25) and the wiring connection portion (17) is disposed outside the radial direction of the coil (12), The electromagnetic coil according to claim 4, wherein the insulating member (15) is also disposed between the connecting wire (27) and the coil case (11).

7. The electromagnetic coil (10) according to any one of claims 1 to 6, A driving-side rotor (2) made of a magnetic material, A driven-side hub (3) rotatable relative to the rotor (2), An armature plate (4) composed of a magnetic material, connected to the hub (3), and disposed opposite to the side end face of the rotor (2) with a gap therebetween. The electromagnetic coil (10) forms a magnetic circuit passing through the rotor (2) and the armature plate (4) when the coil (12) is energized, and is accommodated inside the rotor (2) so as to be capable of generating an attractive force for magnetically attracting the armature plate (4) to the rotor (2). An electromagnetic clutch characterized by the above.

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