Electromagnetic coil and electromagnetic clutch comprising same

Abstract

The present invention addresses the problem of reliably ensuring insulation from a coil case even when a coil is accommodated in the coil case without performing an additional covering step after a connection step for connecting external wiring or the like.　The present invention provides an electromagnetic coil 10 comprising: a magnetic coil case 11 which has an annular accommodation groove 16; a coil 12 which is accommodated directly in the accommodation groove 16; a covering body 13 which covers the entirety of the coil 12; an electrical insulation layer 14 which is constituted by an electrically insulating thermosetting resin that is impregnated in the covering body 13, and which covers at least a surface of the coil 12; and a wiring connection part 17 to which is connected external wiring 20 that supplies power to the coil 12, said electromagnetic coil 10 being characterized in that an insulation member 15 is provided between the wiring connection part 17 and the coil case 11.

Description

Electromagnetic coil and electromagnetic clutch equipped with same

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

[0002] It has been proposed to eliminate the coil bobbin to reduce the size and weight of the electromagnetic coil. Such a bobbinless electromagnetic coil requires electrical insulation between the coil and the side wall of the housing groove of the coil case without using the coil bobbin. Therefore, it has been considered to manufacture the electromagnetic coil using 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 coiled state by temporary fixing tape (holding process), connection ends to be connected to external wiring and component connection parts to be connected to accessory components as needed are pulled out from the bobbinless coil (connection preparation process), the entire bobbinless coil 100 is covered with a coating 101 except for the connection ends 100a and the component connection parts 100b (covering process, see Figure 13A), the bobbinless coil has external wiring 102 connected to the connection ends 100a and accessory components 103 connected to the component connection parts 100b (connection process, see Figure 13B), the connection ends 100a to which the external wiring 102 is connected and the component connection parts 100b to which the accessory components 103 are connected are covered with an additional coating 101a (additional covering process, see Figure 13C), The coil 100 coated with the coating bodies 101, 101a in the coating process or additional coating process is accommodated in the accommodation groove 111 of the coil case 110 (accommodating process), the liquid thermosetting resin and the coil case 110 are preheated (preheating process), the liquid thermosetting resin 112 is poured into the accommodation groove 111 and impregnates the coating bodies 101, 101a (impregnation process, see FIG. 13D ), and the liquid thermosetting resin impregnated into the coating bodies 101, 101a is heated and cured to form the electrical insulating layer 113 (curing process). This series of steps results in an electromagnetic coil in which the coil case 110 and the coil 100 are electrically insulated from each other.

[0004] However, in the above-described process, the connection step connects the external wiring 102 and the accessory parts 103 (such as a thermal fuse or diode) to the connection end 100a and the component connection part 100b of the coil 100 outside the coating 101 wound around the coil. To prevent the connection end 100a and the component connection part 100b from shorting with the coil case 110, an additional coating step is provided after the connection step, in which the coating 101a is manually added to the exposed connection part. This makes the process complicated, and there is a risk of a short circuit if the coating is poorly done manually.

[0005] Therefore, there is a demand for reliable insulation measures for the inside of the coil case while also reducing costs by simplifying the work.

[0006] The present invention has been made in consideration of the above circumstances, and its main objective is to provide an electromagnetic coil that can reliably ensure insulation between the coil case without performing an additional covering process after the connection process, and an electromagnetic clutch equipped with such an electromagnetic coil.

[0007] In order to achieve the above object, the electromagnetic coil of the present invention is an electromagnetic coil (10) comprising: 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 elasticity and resin impregnation properties and covering the entire coil (12); an electrical insulating layer (14) made of an electrically insulating thermosetting resin impregnated in the coating (13) and covering the surface of the coil (12); and a wiring connection part (17) that passes through a through hole (23) of the coil case (11) and to which external wiring (20) that supplies power to the coil (12) is connected, and the electromagnetic coil (10) is characterized in that an insulating member (15) is provided between the wiring connection part (17) and the coil case (11).

[0008] Therefore, when the coil is housed in the coil case after the connection step of connecting external wiring to the wiring connection part, an insulating member is interposed between the wiring connection part and the coil case, so insulation between the wiring connection part and the coil case is reliably ensured, eliminating the need for additional coating of the wiring connection part.

[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 disposed between the inner surface of the annular coil case and the wiring connection portion, using a plate-shaped member makes it easier to arrange the insulating member along the inner surface of the coil case or the outer surface of the coil.

[0011] However, electromagnetic coils generate heat when current is applied, and when used in an electromagnetic clutch, frictional heat is transmitted from the clutch, so they are required to have durability of 150°C or higher. For this reason, it is preferable that the insulating member be made of an insulating material (such as PP, PA, PA66, or Melinex 238) that has heat resistance and a melting point of 150°C or higher.

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

[0013] With this configuration, the insulating member can reliably prevent short circuits from occurring with the inner and outer circumferential walls of the housing groove of the coil case.

[0014] The insulating member (15) may preferably have 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-like shape (insertion groove) or an insertion hole.

[0015] According to this configuration, a wiring insertion portion is provided through which external wiring is inserted into the insulating member, so that the insulating member can be positioned using the external wiring, thereby preventing the insulating member from shifting position and reliably preventing short-circuiting of the wiring connection portion.

[0016] The insulating member (15) may also be configured so that the lengths on both sides in the circumferential direction around the wire insertion portion (15d) are equal.

[0017] With such an insulating member, it is possible for the insulating member to reliably cover the wire connection portions that are arranged at equal positions on both sides of the wire insertion portion in the circumferential direction.

[0018] In addition, the coil (12) has one end face (120a) equipped with the wiring connection portion (17) that connects the external wiring (20), and the other end face (120b) equipped with a temperature fuse (25) and provided on the open end side of the coil case (11), and in an electromagnetic coil (10) in which a crossover wire (27) that electrically connects the temperature fuse (25) and the wiring connection portion (17) is arranged radially outside the coil (12), the insulating member (15) may also be arranged between the crossover wire (27) and the coil case (11).

[0019] In particular, in a coil case where the width of the bottom wall side is narrower than the width of the opening side, when a 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. Furthermore, if the crossover wire is exposed on the side of the coil, the crossover wire is likely to come into contact with the coil case on the side closer to the bottom wall, which may cause a short circuit. Therefore, by disposing an insulating member between the crossover wire and the coil case, it is possible to reliably prevent short circuits regardless of the shape of the coil case.

[0020] Furthermore, even when the connection end (12b) of the coil (12) that connects to the temperature fuse (25) is arranged radially outside the coil (12), the insulating member (15) may also be arranged between the connection end (12b) of the coil (12) and the coil case (11).

[0021] In this configuration, the insulating member is also disposed between the connection end of the coil and the coil case, which makes it possible to reliably prevent short circuits. Note that, in this configuration, it is assumed that the connection end of the coil will be disposed at a position away from the external wiring, so the insulating member may have different lengths on both sides in the circumferential direction around the wiring insertion portion (15d).

[0022] In addition, the insulating member may be provided around the entire circumference of the storage groove of the coil case, and the height of the inner side wall and the outer side wall may be equal, or the height of the inner side wall may be higher than the height of the outer side wall.

[0023] As described above, according to the present invention, in an electromagnetic coil, an insulating member is provided between the coil case and the wiring connection portion to which external wiring that supplies power to the coil is connected, thereby eliminating the need for a process of applying an additional coating with a covering body to insulate the wiring connection portion, thereby simplifying the manufacturing process and reducing costs.

[0024] Furthermore, since the work of applying additional insulating coating is eliminated, there is no need to worry about the insulation state being difficult to ensure due to variations in the state of the additional coating, and reliable insulation between the coil case can be ensured.

[0025] 5 is a diagram illustrating an example of the configuration of an electromagnetic clutch including an electromagnetic coil according to the present invention; FIG. 6 is a cross-sectional view illustrating an example of the configuration of an electromagnetic coil according to the present invention; FIG. 7 is a perspective view illustrating an example of an insulating member used in the electromagnetic coil according to the present invention; FIG. 8 is a plan view illustrating an example of an insulating member used in the electromagnetic coil according to the present invention; FIG. 9 is a view illustrating a connection configuration of external wiring and accessories connected to the electromagnetic coil according to the present invention; FIG. 10 is a perspective view illustrating an actual connection state of the connection configuration of the external wiring and accessories shown in FIG. 4; FIG. 11 is a side view of a state in which an insulating member is attached to the coil in the connected state shown in FIG. 12; FIG. 13 is a perspective view of a state in which an insulating member is attached to the coil, viewed from the side where the external wiring is connected; FIG. 14 is a diagram illustrating a manufacturing process of an electromagnetic coil, and an explanatory diagram illustrating a winding process of the electromagnetic coil; FIG. 15 is a diagram illustrating a manufacturing process of an electromagnetic coil, and an explanatory diagram illustrating a holding process of the electromagnetic coil; FIG. 16 is a diagram illustrating a manufacturing process of an electromagnetic coil, and an explanatory diagram illustrating a component connection preparation process of the electromagnetic coil; FIG. 17 is a diagram illustrating a manufacturing process of an electromagnetic coil, and an explanatory diagram illustrating a covering process of the electromagnetic coil; FIG. 18 is a diagram illustrating a manufacturing process of an electromagnetic coil, and an explanatory diagram illustrating a connecting process of the electromagnetic coil; FIG. 19 is a diagram illustrating a manufacturing process of an electromagnetic coil, and an explanatory diagram illustrating a storage process of the electromagnetic coil. 12A ; FIG. 12B is a diagram illustrating a manufacturing process of an electromagnetic coil, and is an explanatory diagram illustrating a preheating process of the electromagnetic coil and thermosetting resin after the coil is housed in a coil case; FIG. 12C is a diagram illustrating a manufacturing process of an electromagnetic coil, and is an explanatory diagram illustrating a process of injecting and hardening thermosetting resin into the electromagnetic coil; FIG. 12D is a perspective view illustrating another configuration example of an insulating member; FIG. 12E is a diagram illustrating another configuration example of an electromagnetic coil, and is a cross-sectional view thereof; FIG. 12F is a diagram illustrating another configuration example of an electromagnetic coil, and is a perspective view of an insulating member used in the electromagnetic coil of FIG. 12A; FIG. 12G is a diagram illustrating a manufacturing process of a conventional electromagnetic coil, and is an explanatory diagram illustrating a coating process of the electromagnetic coil; FIG. 12H is a diagram illustrating a manufacturing process of a conventional electromagnetic coil, and is an explanatory diagram illustrating a connecting process of the electromagnetic coil; FIG. 12H is a diagram illustrating a manufacturing process of a conventional electromagnetic coil, and is an explanatory diagram illustrating an additional coating process of the electromagnetic coil; FIG. 12I is a diagram illustrating a manufacturing process of a conventional electromagnetic coil, and is an explanatory diagram illustrating a process of impregnating and hardening thermosetting resin.

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the embodiment shown in the accompanying drawings is an example of the present invention, and the present invention is not limited to this embodiment.

[0027] First, an electromagnetic clutch 1 equipped 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 drive-side rotor 2 made of a magnetic material, a driven-side hub 3 that is rotatable relative to the rotor 2, and an armature plate 4 made of a magnetic material, connected to the hub 3, and positioned opposite the side end face of the rotor 2 across a gap.

[0029] The electromagnetic coil 10 is fixed to the casing 5 (e.g., the housing of a compressor) via a fixing plate 8, and is housed inside the rotor 2. When current is applied to this electromagnetic coil 10, a magnetic circuit is formed that passes through the rotor 2 and the armature plate 4, and the armature plate 4 is electromagnetically attracted to the rotor 2.

[0030] The hub 3 is attached to a rotary shaft 6 that protrudes from the housing 5 to the outside so that its relative rotation is restricted.

[0031] The rotor 2 is an annular member centered on the center line CL of the rotary shaft 6, and is configured by 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 by a 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 the side end face of the rotor 2 across a gap. A friction surface 4a is formed on the armature plate 4, which faces the side end face of the rotor 2. The friction surface 4a can engage with the side end face of the rotor 2 by electromagnetic attraction due to deformation of the elastic member.

[0033] Therefore, when the rotor 2 is belt-driven by an external power source and the electromagnetic coil 10 is energized, the armature plate 4 is electromagnetically attracted (engaged) to the rotor 2 and rotates together with the rotor 2, causing the rotating shaft 6 to rotate via the hub 3 that is 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 with a predetermined clearance secured between it and the rotor 2 (pulley). That is, the rotor 2 has an annular housing recess 21 centered on the center line CL, which opens on the end face opposite to the end face facing the armature plate 4. The electromagnetic coil 10 is fixed to the fixing plate 8 disposed so as to face the open end of the housing recess 21, and is inserted into the housing recess 21 so as to form a gap between it and the inner wall of the housing recess 21. Therefore, the rotor 2 is rotatable without coming into contact with the electromagnetic coil 10.

[0035] As also shown in Figure 2, the electromagnetic coil 10 is formed in a ring shape centered on the center line CL of the rotating shaft 6, and has a ring-shaped coil case 11, a coil 12 housed in this coil case 11, a coating 13 that has elasticity and resin-impregnability and covers the entire coil 12, an electrical insulating layer 14 made 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 has a U-shaped cross section with the end opposite the fixed plate 8 being open, and is provided with an inner side wall 11a, an outer side wall 11b, and a bottom wall 11c that connects the ends of these side walls 11a, 11b and closes the end on the fixed plate 8 side, and a ring-shaped storage groove 16 is defined by these side walls 11a, 11b and the bottom wall 11c.

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

[0038] The coil 12 is directly housed in the housing groove 16 of the coil case 11 without a coil bobbin. Such a coil 12 is sometimes called a bobbinless coil.

[0039] The coil (bobbinless coil) 12 is made of a coil winding such as copper wire, and the cross section of the coil is formed in a rectangular shape corresponding to the shape of the accommodation groove 16 of the coil case 11 .

[0040] As described above, the covering 13 is made of a member that is stretchable and resin-impregnable, and may be, for example, a tape-like material made of a highly stretchable nonwoven fabric or the like that can be wound around the coil 12. The thickness of the covering 13 can be adjusted by wrapping the covering 13 around the coil 12 in multiple layers (by multiple windings), and the thickness of the liquid thermosetting resin that is impregnated into the covering 13, in other words, the thickness of the electrical insulation layer 14, can be controlled.

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

[0042] That is, the insulating member 15 is disposed between the insertion end 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 that connects to the external wiring 20 from the coil case 11. As also shown in Fig. 3, the insulating member 15 in this example is composed of an inner side wall 15a, an outer side wall 15b, and a bottom wall 15c that connects the ends of these side walls 15a, 15b together.

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

[0044] Furthermore, a wiring insertion portion 15d, through which the external wiring 20 is inserted, is formed in the approximate circumferential center of the bottom wall 15c of the insulating member 15. In this example, the wiring insertion portion 15d is configured by cutting out the center of the inner side wall 15a to form a wiring insertion groove that extends circumferentially in the bottom wall 15c. Therefore, the insulating member 15 extends by the same length on both sides of the wiring insertion portion 15d in the circumferential direction.

[0045] The height β (length from the bottom wall 15c) of the outer peripheral side wall 15b is greater 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 of the outer peripheral surface of the coil 12 along the center line CL.

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

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

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

[0049] At this time, for ease of operation, the other connection end 12b of the coil 12 and the connecting wire 27 are routed along the outer side surface of the coil 12 between the coil lower surface 120a and the coil upper surface 120b, as shown in Figures 5 and 6. The storage groove 16 of the coil case 11 is formed to narrow 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 side wall 15b of the insulating member 15 is made longer than the length (height) of the inner side wall 15a. In the lower half portion where the other connection end 12b of the coil 12 and the connecting wire 27 are easily accessible to the coil case 11, the outer side wall 15b can bring the connection end 12b and the connecting wire 27 closer to the coil. This ensures that the connection end 12b and the connecting wire 27 are separated from the coil case 11, while the insulating member 15 provides insulation between them and the coil case 11.

[0050] 7, the insulating member 15 is attached to the coil 12 covered by the cover 13, with the external wiring 20 connected to the wiring connection portion 17 drawn out through the wiring insertion portion 15d. Then, as shown in FIG. 10, the coil 12 in this state is housed in the housing groove 16 of the coil case 11. Thereafter, the coil 12 housed in the housing groove 16 is injected with a thermosetting resin that forms the electrical insulating layer 14. As a result, the coil 12 and the insulating member 15 are fixed to the coil case 11.

[0051] When injecting thermosetting resin into a coil 12 equipped with a thermal fuse 25, the thermosetting resin is injected so that it adheres to the thermal fuse 25 and the component connection portions 30a, 30b, thereby fixing the thermal fuse 25 to the coil 12.

[0052] Next, a method for manufacturing the electromagnetic coil 10 using the 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 connecting step of connecting the external wiring 20 .

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

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

[0056] After this holding step, as shown in FIG. 8C, the connection ends 12a and 12b to be connected to the external wiring 20 and the thermal fuse 25 are drawn out from the coil 12 (component connection preparation step).

[0057] After this component connection preparation step, as shown in Fig. 9A, the entire coil 12 except for the connection ends 12a and 12b is covered with the covering 13 (covering step). This covering step is performed by winding, for example, a tape-like covering 13 around the coil 12 using a winding machine (not shown). This covering step allows the coil 12 to be electrically insulated from the connection ends 12a and 12b and the coil case 11.

[0058] 9B , after this covering step, the coil 12 has the external wiring 20a and one end 26a of the diode 26 connected to the connection end 12a by the wiring connection portion 17a, and one end 25a of the thermal fuse 25 connected to the connection end 12b by the component connection portion 30a, and further the other end 25b of the thermal fuse 25 is connected to one end 27a of the crossover wire 27 by the component connection portion 30b. The other end 27b of the crossover wire 27 is connected to the external wiring 20b and the other end 26b of the diode 26 by the wiring connection portion 17b.

[0059] The wiring connection portions 17a, 17b may be electrically connected to the respective conductors and components by crimping sleeves, welding, or soldering. The component connection portions 30a, 30b may also be connected by crimping sleeves, welding, or soldering.

[0060] After this connection step, in the past, the coil 12 would undergo an additional coating step in which the wiring connection portions 17a, 17b, diode 26, and connecting wire 27 exposed from the coating 13 are covered with an additional coating. However, here, no additional coating with a coating is performed, and the wiring connection portions 17a, 17b, diode 26, and connecting wire 27 are covered with insulating member 15 (see Figure 5). Furthermore, as shown in Figures 6 and 7, after the external wiring 20 is pulled out from the wiring insertion portion 15d, the insulating member 15 is attached to the underside 120a of the coil 12 on which the coating 13 is wound, from above the wiring connection portions 17a, 17b, diode 26, and connecting wire 27 (insulating member attachment step).

[0061] Since the wiring connections 17 a and 17 b , the diode 26 , and the crossover wire 27 are exposed from the coating 13 , a gap is formed between the insulating member 15 and the coating 13 .

[0062] 10A , after this insulating member attachment step, the coil 12 with the insulating member 15 attached is stored in the storage groove 16 of the coil case 11 from the insulating member 15 side (storing step). At this time, the external wiring 20 is passed through the grommet 22, and the external wiring 20 and grommet 22 are inserted into the through-hole 23 and through-hole 81 of the coil case 11, with the grommet 22 fitting into the through-hole 23. In this storing step, the coil case 11 is set in advance in a case holding jig (not shown) with the fixing plate 8 fixed to the bottom wall 11c in advance. In this set state, the coil case 11 is fixed with the fixing plate 8 facing downward and the open end of the storage groove 16 facing upward.

[0063] 10B, the coil 12 is stored in the storage groove 16 together with the insulating member 15 (storing step). Note that, as shown in the same 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 storing step, the thermosetting resin 70 and the coil case 11 are preheated to maintain the fluidity of the electrically insulating liquid thermosetting resin 70 (preheating step). After this preheating step, as shown in FIG. 10C , the liquid thermosetting resin 70 is poured into the storing groove 16, so that the liquid thermosetting resin 70 impregnates the coating 13, and the thermosetting resin is poured into all 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 (resin pouring step). At this time, the liquid thermosetting resin 70 to be supplied into the coil case 11 may be a predetermined amount stored in a container 81, preheated by a heater 82, and poured into the storing groove 16. After a certain time has passed since the resin was poured, the liquid thermosetting resin 70 evenly impregnates the coating 13.

[0065] After the resin injection process, the poured liquid thermosetting resin 70 is heated and hardened to form the electrical insulating layer 14 (hardening process). For example, the coil case 11 after the resin injection process is placed in a hardening heating furnace and heated, whereby the liquid thermosetting resin 70 is hardened.

[0066] After this hardening step, the coil case 11 is cooled to room temperature, thereby completing the series of steps for manufacturing the electromagnetic coil 10.

[0067] Therefore, according to the above-mentioned electromagnetic coil, an insulating member 15 is provided at least between the wiring connection portions 17a, 17b to which external wiring is connected and the coil case 11, so that it is possible to reliably insulate the wiring connection portions 17a, 17b without applying additional coating.

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

[0069] Furthermore, the insulating member 15 has not only a bottom wall 15c but also an inner side wall 15a and an outer side wall 15b, providing insulation between the corresponding wall surfaces of the coil case 11. Therefore, even if the positions of the wiring connection portions 17a, 17b and the crossover wire 27 are shifted when the coil 12 is accommodated in the storage groove 16, insulation between the coil case 11 can be reliably ensured.

[0070] Furthermore, since the length (height) of the outer side wall 15b of the insulating member 15 is greater than the length (height) of the inner side wall 15a, the insulating member can move the crossover wire 27 closer to the coil in the lower half where the crossover wire 27 is more likely to come close to the coil case 11, thereby ensuring insulation between the crossover wire 27 and the coil case 11.

[0071] Furthermore, in this embodiment, the wire insertion portion of the insulating member is formed in the center, and insulating regions of equal length are provided on both sides (the circumferential lengths of the side walls and bottom wall are equal on the left and right), so it is possible to insulate areas where wire connections tend to concentrate with insulating member 15 of just the right length. In other words, since insulating member 15 is formed with equal circumferential lengths on the left and right sides around wire insertion portion 15d as the center, it is possible to avoid the inconvenience of insulating member 15 being too short in the circumferential direction to maintain insulation when connection ends are provided at equal positions from wire insertion portion 15d, and it is also possible to avoid the inconvenience of insulating member 15 being too long in the circumferential direction to increase the number of wasted portions that do not contribute to insulation.

[0072] In the above-described configuration, as shown in FIGS. 5 to 7, the wiring connection portions 17a, 17b to which external wiring is connected are covered by a bilaterally symmetrical insulating member 15. However, when the thermal fuse 25 is provided on the open end side of the coil case 11, the conductor connecting the open end side and the bottom wall side of the coil case along the outer circumferential surface of the coil 12 is exposed at both ends of the thermal fuse 25. The crossover wire 27 corresponds to one of the conductors, but both conductors are not necessarily disposed in bilaterally symmetrical positions with respect to the wiring insertion portion 15d. Therefore, in such a case, as shown in FIG. 11, the insulating member 15 may be asymmetrically shaped so that the circumferential length on one side of the wiring insertion portion 15d is longer than the circumferential length on the other side, thereby ensuring insulation between the conductors connected to both ends of the thermal fuse and the coil case 11.

[0073] In the above example, the outer peripheral side wall 15b of the insulating member 15 is made longer than the inner peripheral side wall 15a to ensure reliable insulation between the coil case 11 and the conductors (the crossover wire 27 and the other connection end 12b of the coil 12) connecting the open end and bottom wall of the coil case 11 on the outer peripheral side. However, this shape is not limited to this, and the inner peripheral side wall 15a may also have a height similar to that of the outer peripheral side wall 15b. Furthermore, the height of the side walls may be such that they cover the entire height (axial length) of the coil 12. Furthermore, the side walls 15a and 15b may be provided around the entire circumference of the storage groove 16. For example, an insulating member 15 (both the inner peripheral side wall 15a and the outer peripheral side wall 15b) as shown in FIG. 12 may be used, in which the height covers the entire height (axial length) of the coil 12 and the insulating member is formed in a ring shape around the entire circumference of the storage groove 16.

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

[0075] The present invention relates to an exciting coil and an electromagnetic clutch incorporating the same, and can be used in devices equipped with a mechanism for transmitting or interrupting rotational power by utilizing electromagnetic force.

[0076] REFERENCE SIGNS LIST 1 electromagnetic clutch 10 electromagnetic coil 11 coil case 12 coil 12a, 12b connection end 13 coating 14 electrical insulating layer 15 insulating member 15a inner circumferential side wall 15b outer circumferential side wall 15c bottom wall 15d wiring insertion portion 16 storage groove 17, 17a, 17b wiring connection portion 20 external wiring 23 through hole 25 thermal fuse 27 wire crossover

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 elasticity and resin impregnation property and covering the whole of the coil (12), an electric insulation layer (14) formed of an electric insulating thermosetting resin impregnated in the coating (13) and covering at least the surface of the coil (12), and a wiring connection part (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 the electromagnetic coil (10), an insulating member (15) is provided between the wiring connection part (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 electric 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 the ends of these side walls (15a, 15b).

4. The electromagnetic coil according to claim 1, wherein the insulating member (15) is provided with a wiring insertion part (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 respect to the wiring insertion part (15d).

6. The coil 12 has one end face (120a) provided with the wiring connection part (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 the electromagnetic coil (10) in which a connecting wire (27) for electrically connecting the temperature fuse (25) and the wiring connection part (17) is disposed outside the coil (12) in the radial direction, 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) made 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, wherein the electromagnetic coil (10) is housed inside the rotor (2) so as to form a magnetic circuit passing through the rotor (2) and the armature plate (4) when the coil (12) is energized, and capable of generating an attractive force for magnetically attracting the armature plate (4) to the rotor (2). An electromagnetic clutch (1) characterized by the above.

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