Ignition coil for internal combustion engine

Abstract

To provide an ignition coil for an internal combustion engine capable of achieving productivity improvement and miniaturization of an ignition coil.SOLUTION: An ignition coil for an internal combustion engine includes a primary and a secondary coils, a circuit board on which an electronic circuit is formed, a coil case in which the primary coil, the secondary coil, and the circuit board 6 are accommodated, and a connector disposed on the coil case, in which a plurality of connector terminals 31 are provided. A plurality of groove parts 61 each having a conductor layer provided on its inner lateral surface are formed at an either end part 601 of the circuit board 6. A relay terminal 23 connected to each of a pair of coil end parts of the primary coil, a relay terminal 23 connected to a low-voltage side coil end of the secondary coil, and the plurality of connector terminals 31 are electrically connected to the conductor layer by being inserted to the groove parts 61.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an ignition coil for an internal combustion engine. [Background technology]

[0002] An ignition coil for an internal combustion engine is used to ignite a mixture of fuel and combustion air in a combustion chamber of the engine as an internal combustion engine. The ignition coil includes a primary coil, a secondary coil arranged coaxially around the outer periphery of the primary coil and magnetically coupled to the primary coil, and a circuit board that energizes and cuts off the energization of the primary coil. Each component, such as the primary coil, secondary coil, and igniter, is arranged in a coil case, and a filling resin is filled in the gaps in the coil case to insulate and fix each component. The circuit board may be embedded in the filling resin in a molded state with the molding resin, or may be embedded in the filling resin in an unmolded state.

[0003] The coil case also includes a connector portion provided with a connector terminal, which is connected to a circuit terminal drawn out from the circuit board, and the coil ends of the primary coil and the secondary coil are connected to the connector terminal or the circuit terminal via a relay terminal or the like.

[0004] For example, in the ignition coil of Patent Document 1, it is described that multiple output terminals of the coil and multiple connector terminals of the connector are connected to multiple circuit terminals provided on an electronic circuit board by press-fitting. This press-fit connection prevents foreign matter such as spatter and fumes generated during welding from adhering to the coil. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2010 / 149195A1 publication Summary of the Invention [Problem to be solved by the invention]

[0006] In the ignition coil of Patent Document 1, it is necessary to provide multiple circuit terminals protruding from the end face or surface of the electronic circuit board. Providing these multiple circuit terminals increases the number of parts in the ignition coil, which is an obstacle to simplifying the manufacturing process of the ignition coil. Furthermore, providing multiple circuit terminals is an obstacle to miniaturizing the ignition coil. Therefore, further ingenuity is required to improve the productivity and miniaturization of the ignition coil.

[0007] The present invention has been made in view of the above problems, and aims to provide an ignition coil for an internal combustion engine that can improve the productivity and reduce the size of the ignition coil. [Means for solving the problem]

[0008] One aspect of the present invention is A primary coil (21) and a secondary coil (22), A circuit board (6) on which an electronic circuit is formed; a coil case (5) in which the primary coil, the secondary coil, and the circuit board are housed; a connector (3) disposed in the coil case and provided with a plurality of connector terminals (31); A plurality of grooves (61) are formed at either end of the circuit board, and the grooves (61) have conductor layers (62A) on their inner surfaces (611), At least one of the coil end (211) of the primary coil, the coil end (221) of the secondary coil, the relay terminal (23) connected to the coil end of the primary coil, and the relay terminal (23) connected to the coil end of the secondary coil, as well as at least one of the multiple connector terminals, are inserted into the groove portion and electrically connected to the conductor layer in an ignition coil (1) for an internal combustion engine. Effect of the Invention

[0009] In the ignition coil for an internal combustion engine according to the above aspect, a plurality of grooves with conductor layers provided on the inner surfaces are formed at either end of the circuit board, and at least one of the coil ends of the primary coil, the coil ends of the secondary coil, the relay terminals connected to the coil ends of the primary coil, and the relay terminals connected to the coil ends of the secondary coil, and at least one of the plurality of connector terminals are inserted into the grooves and electrically connected to the conductor layers.

[0010] By forming such a groove having a conductor layer, it is not necessary to provide metal fittings such as terminals on the circuit board. Therefore, the number of parts in the ignition coil can be reduced, and the manufacturing process of the ignition coil can be simplified. Also, the space required for electrically connecting the coil end, relay terminal, or connector terminal to the circuit board can be reduced. Therefore, the ignition coil can be made smaller.

[0011] Therefore, according to the ignition coil for an internal combustion engine of the above aspect, it is possible to improve the productivity of the ignition coil and reduce its size.

[0012] In addition, the symbols in parentheses for each component shown in one aspect of the present invention indicate a correspondence with the symbols in the figures in the embodiment, but do not limit each component to only the contents of the embodiment. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram showing a cross section of an ignition coil for an internal combustion engine according to a first embodiment, as viewed from the front. [Diagram 2] FIG. 2 is an explanatory diagram showing a cross section of an ignition coil for an internal combustion engine according to the first embodiment in a state where no filling resin is filled, as viewed from above. [Diagram 3] FIG. 3 is an explanatory diagram showing the ignition coil for an internal combustion engine according to the first embodiment in a state where no filling resin is filled, as viewed from above. [Figure 4]FIG. 4 is a perspective view showing a part of the circuit board in which the relay terminals and the connector terminals are inserted into the grooves according to the first embodiment. [Diagram 5] FIG. 5 is a perspective view showing a part of the circuit board before the relay terminals and the connector terminals are inserted into the grooves according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing a part of the circuit board in which the relay terminal or the connector terminal is inserted into the groove according to the first embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing a part of a circuit board in which a relay terminal or a connector terminal is inserted into a groove according to the second embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing a part of another circuit board in which a relay terminal or a connector terminal is inserted into a groove according to the second embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a part of another circuit board in which a relay terminal or a connector terminal is inserted into a groove according to the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a part of another circuit board in which a relay terminal or a connector terminal is inserted into a groove according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A preferred embodiment of the above-mentioned ignition coil for an internal combustion engine will be described with reference to the drawings. <Embodiment 1> 1 to 3, the ignition coil 1 for an internal combustion engine of this embodiment includes a primary coil 21, a secondary coil 22, a circuit board 6 on which an electronic circuit is formed, a coil case 5 that houses the primary coil 21, the secondary coil 22, and the circuit board 6, and a connector 3 that is disposed in the coil case 5 and has a plurality of connector terminals 31. At one end 601 of the circuit board 6, a plurality of grooves 61 are formed, each having a conductor layer 62A provided on an inner surface 611.

[0015] The relay terminals 23 respectively connected to a pair of coil ends 211 of the primary coil 21, the relay terminals 23 connected to the coil end 221 of the low-voltage side L2 of the secondary coil 22, and the multiple connector terminals 31 are inserted into the groove portion 61 and electrically connected to the conductor layer 62A.

[0016] The ignition coil 1 for an internal combustion engine according to this embodiment will be described in detail below. (Ignition coil 1) As shown in Fig. 1, an ignition coil 1 is disposed in a cylinder head cover of an engine as an internal combustion engine of a vehicle, and is used to generate a spark discharge in a combustion chamber of the cylinder head from a spark plug disposed in the cylinder head. The ignition coil 1 of this embodiment is for mounting on a vehicle. The ignition coil 1 has a coil body 11 constituted by a primary coil 21, a secondary coil 22, etc., and a joint portion 12 protruding from the coil body 11 for electrically connecting the secondary coil 22 and the spark plug. The coil body 11 is disposed in the cylinder head cover, and the joint portion 12 is disposed in a plug hole of the cylinder head cover.

[0017] As shown in Fig. 1 and Fig. 2, the ignition coil 1 includes an inner core 41, an outer core 42, a coil case 5, a filled resin 7, etc., in addition to the primary coil 21, the secondary coil 22, and the circuit board 6. The inner core 41 is disposed inside the primary coil 21 and the secondary coil 22, and the outer core 42 is disposed outside the primary coil 21 and the secondary coil 22. The primary coil 21, the secondary coil 22, the inner core 41, the outer core 42, and the circuit board 6 are housed in the coil case 5. Gaps in the coil case 5 are filled with the filled resin 7. Figs. 2 and 3 show the ignition coil 1 in a state in which the coil case 5 is not filled with the filled resin 7.

[0018] (Axial direction L, installation direction D, horizontal direction W) As shown in Figs. 1 to 3, in the ignition coil 1, the direction in which the central axes of the primary coil 21 and the secondary coil 22 extend is referred to as the axial direction L. In the axial direction L, the side where a high voltage is generated in the secondary coil 22 is referred to as the high-voltage side L1, and the opposite side of the high-voltage side L1 is referred to as the low-voltage side L2. The direction perpendicular to the axial direction L and in which the bottom 52 and the opening 53 of the coil case 5 are aligned is referred to as the mounting direction D. In the mounting direction D, the side where the bottom 52 is located and where the spark plug is arranged is referred to as the bottom side D1, and the side opposite the bottom side D1 and where the opening 53 is located is referred to as the opening side D2. The direction perpendicular to both the axial direction L and the mounting direction D is referred to as the lateral direction W.

[0019] (Primary coil 21) As shown in Fig. 1 and Fig. 2, the primary coil 21 is formed by winding a magnet wire as a winding around the outer circumferential surface of a primary spool 210 made of a thermoplastic resin. The primary coil 21 is formed of a conductive conductor and an insulating coating layer provided around the conductor. The primary coil 21 is repeatedly energized and cut off by a switching element of a circuit board 6 that receives a command from an engine control device. An end of the winding of the primary coil 21 is connected to a conductor layer of a power source or a switching element on the circuit board 6 via a relay terminal 23.

[0020] (Secondary coil 22) 1 and 2, the secondary coil 22 is disposed coaxially with the primary coil 21 on the outside of the primary coil 21. The secondary coil 22 is formed by winding a magnet wire as a winding around the outer circumferential surface of a secondary spool 220 made of a thermoplastic resin. The secondary coil 22 is formed of a conductive conductor and an insulating coating layer provided around the conductor.

[0021] The secondary coil 22 has a smaller winding than the primary coil 21, and the number of windings is greater than that of the primary coil 21. The secondary coil 22 generates an induced electromotive force by mutual induction when the current to the primary coil 21 is cut off. The central axes of the primary coil 21 and the secondary coil 22 are oriented in a direction perpendicular to the opening 53 of the coil case 5. An end of the low-voltage side L2 of the winding of the secondary coil 22 is connected to a conductor layer of the ground or power supply in the circuit board 6 via a relay terminal 23. An end of the high-voltage side L1 of the winding of the secondary coil 22 is connected to a high-voltage terminal 24 connected to a center electrode of the spark plug.

[0022] (Relay terminal 23) As shown in the figure, a pair of coil ends 211 of the primary coil 21 in this embodiment are provided with conductive relay terminals 23 for insertion into the grooves 61 of the circuit board 6. In addition, a coil end 221 on the low-voltage side L2 of the secondary coil 22 is provided with a relay terminal 23 for insertion into the grooves 61 of the circuit board 6. The relay terminals 23 are provided on each of the coil ends 211, 221 of the primary coil 21 or the secondary coil 22 to facilitate electrical connection of the coil ends 211, 221 of the primary coil 21 or the secondary coil 22 to the circuit board 6. The relay terminals 23 may be attached to the primary spool 210 or the secondary spool 220, or may be provided on the primary spool 210 or the secondary spool 220 by insert molding. The coil ends 211, 221 of the primary coil 21 and the secondary coil 22 may be directly inserted into the grooves 61 of the circuit board 6 without using the relay terminals 23.

[0023] (Inner core 41) 1 and 2, an inner core 41 for passing magnetic flux generated by the primary coil 21 and the secondary coil 22 is disposed inside (on the inner circumferential side) of the primary coil 21. The inner core 41 in this embodiment is formed by laminating a plurality of plate-shaped electromagnetic steel sheets made of a soft magnetic material. The inner core 41 may be formed by compression molding powder made of a soft magnetic material.

[0024] (Outer core 42) 1 and 2, an outer core 42 is disposed on the outside (outer periphery) of the secondary coil 22 to pass magnetic flux generated by the primary coil 21 and the secondary coil 22. The inner core 41 and the outer core 42 form a closed magnetic path through which the magnetic flux passes. The outer core 42 in this embodiment is formed by laminating a plurality of plate-shaped electromagnetic steel sheets made of a soft magnetic material. The outer core 42 may be formed by compression molding powder made of a soft magnetic material.

[0025] A closed magnetic path through which magnetic flux passes is formed by the inner core 41 and the outer core 42. A permanent magnet 43 is disposed between the inner core 41 and the outer core 42 to prevent magnetic saturation.

[0026] (Coil case 5) 1 and 2, the coil case 5 is formed as a molded product of a thermoplastic resin. The coil case 5 has a housing portion 51 that houses the primary coil 21, the secondary coil 22, the inner core 41, the outer core 42, the circuit board 6, etc. The coil case 5 has an opening 53 for disposing a coil assembly in which the primary coil 21, the secondary coil 22, the inner core 41, the outer core 42, the circuit board 6, etc. are assembled, in the housing portion 51. The coil case 5 has a bottom portion 52 located on the joint portion 12 side, a side wall portion 54 standing from the periphery of the bottom portion 52, and the opening portion 53 located on the opening side D2 in the mounting direction D of the side wall portion 54.

[0027] (Connector 3) 1 and 2, the connector 3 is formed as a molded product of thermoplastic resin, and is disposed on a side wall 54 of the coil case 5. A portion of the side wall 54 on the low-voltage side L2 in the axial direction L of the coil case 5 is formed by the connector 3. The connector 3 of this embodiment is mounted in a mounting notch 56 formed in the side wall 54. At an end of the connector 3 on the bottom side D1 in the mounting direction D and at both ends in the lateral direction W, clamping portions 32 are formed to clamp the edges of the mounting notch 56 from both sides.

[0028] The connector 3 is provided with a plurality of conductive connector terminals 31 by insert molding, which are inserted into grooves 61 of the circuit board 6. The connector 3 is attached to the coil case 5 in a state in which the connector terminals 31 protrude to the outside of the coil case 5. The multiple connector terminals 31 are arranged in the connector 3 in a state in which they are aligned in the lateral direction W of the ignition coil 1.

[0029] A mating connector is attached to the connector 3 for electrically connecting the ignition coil 1 to an engine control device. Both ends of the multiple connector terminals 31 face toward the inside and outside of the coil case 5. The connector terminals 31 are used for power supply, ground, ignition signals, ignition detection, etc.

[0030] (Circuit board 6) As shown in Figs. 1 to 3, the ignition coil 1 includes a circuit board 6 for repeatedly energizing and cutting off the primary coil 21 upon receiving a command from an engine control device. In other words, the circuit board 6 has a function of energizing and cutting off the primary coil 21 by a switching signal sent from the outside using the connector terminal 31 of the connector 3. The circuit board 6 is disposed facing a portion of the low-voltage side L2 of the outer core 42 in the axial direction L of the primary coil 21 and the secondary coil 22. The circuit board 6 is disposed between the connector 3 attached to the coil case 5 and the axial direction L of the primary coil 21, the secondary coil 22, the inner core 41, and the outer core 42. The circuit board 6 is provided with electronic components such as switching elements that form a switching circuit.

[0031] In the ignition coil 1, a plurality of circuit boards 6 each having a groove 61 formed therein may be arranged. In addition, the circuit board 6 each having a groove 61 formed therein may have a function other than the function of supplying and cutting off current to the primary coil 21.

[0032] In the circuit board 6, the direction in which a pair of plate surfaces (widest surfaces) are aligned and which faces the axial direction L of the ignition coil 1 is referred to as the plate thickness direction T. Moreover, the direction perpendicular to the plate thickness direction T and which faces the lateral direction W of the ignition coil 1 is referred to as the width direction B. Moreover, the direction perpendicular to both the plate thickness direction T and the width direction B is referred to as the depth direction F. In the depth direction F, the bottom side D1 in the mounting direction D is referred to as the bottom side F1, and the opening side D2 in the mounting direction D is referred to as the opening side F2.

[0033] In another embodiment of the ignition coil 1, the thickness direction T of the circuit board 6 may be oriented in the lateral direction W of the ignition coil 1, and the width direction B of the circuit board 6 may be oriented in the axial direction L of the ignition coil 1.

[0034] The circuit board 6 is formed in an exposed state without being molded with the molding resin, in other words in a state in which it is in contact with the filling resin 7 filled in the coil case 5. A plurality of grooves 61 are formed in an end portion 601 of the circuit board 6 located on the side of the opening 53 of the coil case 5, penetrating in the thickness direction T of the circuit board 6 and aligned in the width direction B of the circuit board 6. The plurality of grooves 61 are formed in a recessed state from the opening side F2 to the bottom side F1 in the depth direction F of the circuit board 6. With these configurations, the space required for electrically connecting the relay terminals 23 and the connector terminals 31 to the grooves 61 of the circuit board 6 can be reduced.

[0035] The circuit board 6 has an insulating base material 60 made of resin, glass fiber, glass nonwoven fabric, or the like, and conductive conductor layers 62A, 62B provided on the surface of the insulating base material 60. The conductor layer 62A provided on a pair of inner sides 611 of the groove portion 61 is connected to a conductor layer 62B provided on the surface of the circuit board 6 and electrically connected to various electronic components such as switching elements. Each of the conductor layers 62A, 62B is formed by plating, etching, or the like on the insulating base material 60.

[0036] (Relationship between the circuit board 6, the relay terminal 23, and the connector terminal 31) 1 to 5, the pair of relay terminals 23 of the primary coil 21 and the relay terminal 23 on the low-voltage side L2 of the secondary coil 22 are inserted into the groove 61 of the circuit board 6 from one side in the plate thickness direction T of the circuit board 6, that is, from the high-voltage side L1 in the axial direction L of the ignition coil 1. The multiple connector terminals 31 are inserted into the groove 61 of the circuit board 6 from the other side in the plate thickness direction T of the circuit board 6, that is, from the low-voltage side L2 in the axial direction L of the ignition coil 1.

[0037] The relay terminal 23 and the connector terminal 31 are elongated with a predetermined length and have a flat cross section. The relay terminal 23 and the connector terminal 31 are formed in a predetermined shape that extends to a position determined according to the application. The flat shape means a cross section that is flat and has a thickness that is thin in one direction, such as a rectangular shape.

[0038] As shown in FIG. 4 and FIG. 5, the thickness direction of the relay terminals 23 and the connector terminals 31 is directed to the width direction B of the circuit board 6. The thickness direction refers to the direction in which the length of the side is the smallest. That is, the thickness direction of the relay terminals 23 and the connector terminals 31 is directed to a direction perpendicular to the board thickness direction T of the circuit board 6 so as to easily contact the conductor layer 62A of the groove portion 61 of the circuit board 6 and to easily insert the relay terminals 23 and the connector terminals 31 into the groove portion 61. The surfaces on both sides in the thickness direction of the relay terminals 23 and the connector terminals 31 are in contact with the conductor layer 62A provided on a pair of inner sides 611 located on both sides of the width direction B of the groove portion 61. This configuration can appropriately ensure the contact area between the relay terminals 23 and the connector terminals 31 and the conductor layer 62A of the groove portion 61. In FIG. 4 and FIG. 5, the shapes of the relay terminals 23, the connector terminals 31, and the groove portion 61 are simply shown.

[0039] As shown in FIG. 6, a protruding portion 613 is formed in a part of a depth direction F perpendicular to both the plate thickness direction T and the width direction B of the circuit board 6 on one of the pair of inner sides 611 of the groove portion 61 so as to reduce the width in the width direction B between the pair of inner sides 611. The conductor layer 62A of the groove portion 61 is provided on at least the protruding portion 613 on one inner side surface 611 and the other inner side surface 611. The surfaces in the thickness direction of the relay terminal 23 and the connector terminal 31 are in contact with the conductor layer 62A provided on the protruding portion 613 of one inner side surface 611 and the conductor layer 62A provided on the other inner side surface 611. With these configurations, it is possible to reduce the resistance when the relay terminal 23 and the connector terminal 31 are fitted into the groove portion 61 and to make it difficult for the relay terminal 23 and the connector terminal 31 to come out of the groove portion 61. Furthermore, by forming the protruding portion 613, it is possible to apply an appropriate surface pressure (pressing force) from the protruding portion 613 to the relay terminal 23 or the connector terminal 31 so as to make them less likely to come off.

[0040] Further, the width between the pair of inner side surfaces 611 in the groove 61, in other words the width between the conductor layer 62A of the protruding portion 613 of one inner side surface 611 and the conductor layer 62A of the other inner side surface 611, is smaller than the thickness of the relay terminal 23 and the thickness of the connector terminal 31. The relay terminal 23 and the connector terminal 31 are press-fitted (inserted) into the groove 61. Note that the conductor layer 62A in this embodiment may be provided on the entire pair of inner side surfaces 611 and the bottom surface 612 of the groove 61. In this embodiment, the relay terminal 23 and the connector terminal 31 are not welded to the conductor layer 62A of the groove 61.

[0041] 6, a pair of chamfered or tapered surfaces are formed on the ends of the relay terminal 23 and the connector terminal 31 that are inserted into the groove 61, in other words, the ends 231, 311 located on the bottom side D1 in the depth direction F. This configuration makes it easy to press the relay terminal 23 and the connector terminal 31 into the groove 61. Note that each end of the relay terminal 23 and the connector terminal 31 may be formed with a curved shape instead of a chamfered shape or a tapered surface.

[0042] (Action and effect) In the ignition coil 1 for an internal combustion engine of this embodiment, a plurality of grooves 61, each having a conductor layer 62A provided on an inner surface 611, are formed side by side in the width direction B at an end 601 of an opening side D2 in a depth direction F of a circuit board 6. The relay terminals 23 provided at a pair of coil ends 211 of the primary coil 21, the relay terminals 23 provided at the coil end 221 on the low-voltage side L2 of the secondary coil 22, and the plurality of connector terminals 31 are press-fitted into the grooves 61 and electrically connected to the conductor layer 62A of the grooves 61.

[0043] By forming the groove portion 61 having such a conductor layer 62A, it is not necessary to provide metal fittings such as terminals on the circuit board 6. Therefore, the number of parts in the ignition coil 1 can be reduced, and the manufacturing process of the ignition coil 1 can be simplified. Also, in the ignition coil 1, the space required for electrically connecting the relay terminal 23 and the connector terminal 31 to the circuit board 6 can be reduced. Therefore, the ignition coil 1 can be made more compact.

[0044] Since the groove portion 61 is formed in the circuit board 6, it is possible to allow the relay terminal 23 or the connector terminal 31 to be misaligned with respect to the thickness direction T of the circuit board 6. That is, the end portion of the relay terminal 23 or the end portion of the connector terminal 31 can be formed in a linear shape. Even if the position of the relay terminal 23 or the connector terminal 31 is misaligned with respect to the thickness direction T of the circuit board 6, no difference occurs in the contact state between the relay terminal 23 or the connector terminal 31 and the conductor layer 62A of the groove portion 61. Therefore, the positional deviation of the relay terminal 23 or the connector terminal 31 with respect to the thickness direction T of the circuit board 6 is allowed.

[0045] Therefore, according to the ignition coil 1 for an internal combustion engine of this embodiment, the productivity of the ignition coil 1 can be improved and the size of the ignition coil 1 can be reduced.

[0046] <Embodiment 2> In this embodiment, the shape of the periphery of a groove 61 of a circuit board 6 is different from that in the first embodiment. As shown in FIG. 7, the groove 61 of the circuit board 6 may be formed in a wedge shape. The groove 61 in this embodiment is formed in a shape in which the width between the pair of inner sides 611 narrows from the front to the back (toward the bottom side D1 in the depth direction F). A conductor layer 62A is formed on the pair of inner sides 611. The width between the pair of inner sides 611 changes from a state larger than the width of the relay terminal 23 or the connector terminal 31 to a state smaller than the width of the relay terminal 23 or the connector terminal 31. In this case, when the relay terminal 23 or the connector terminal 31 is press-fitted from the opening side F2 to the bottom side F1 of the groove 61 in the depth direction F, a pressing force can be applied from the pair of inner sides 611 to the relay terminal 23 or the connector terminal 31.

[0047] 7, the pair of inner side surfaces 611 of the groove portion 61 have chamfered ends 611A on the opening side F2 in the depth direction F. This configuration also makes it easier to press-fit the relay terminal 23 and the connector terminal 31 into the groove portion 61. Note that the ends 611A of the inner side surfaces 611 of the groove portion 61 may have a curved shape instead of a chamfered shape.

[0048] As shown in FIG. 8, a convex portion 614 that contacts one of the inner surfaces 611 of the groove portion 61 may be formed on one surface in the thickness direction of the relay terminal 23 and one surface in the thickness direction of the connector terminal 31. In this embodiment, the convex portion 614 is formed as a convex portion 614 on the bent side by bending a part of the relay terminal 23 or the connector terminal 31 so as to be offset in the thickness direction. A concave portion 615 is formed on the opposite side of the convex portion 614. The width between the convex portion 614 on one surface of the relay terminal 23 or the connector terminal 31 and the other surface is larger than the width between the pair of inner surfaces 611 of the groove portion 61. In this case, when the relay terminal 23 or the connector terminal 31 is press-fitted from the opening side F2 to the bottom side F1 in the depth direction F of the groove portion 61, a pressing force can be applied to the relay terminal 23 or the connector terminal 31 from the pair of inner surfaces 611.

[0049] 9, a through hole 616 may be formed in the circuit board 6 at a position adjacent to the outer side of the protruding portion 613 in the width direction B, penetrating the circuit board 6 in the plate thickness direction T, for imparting elastic force to the protruding portion 613. By forming the through hole 616, an elastic force imparting portion 617 is formed by a part of the protruding portion 613 on the pair of inner side surfaces 611 of the groove portion 61. The elastic force imparting portion 617 is formed in a linear manner so as to be elastically deformable.

[0050] In this case, the elastic force imparted to the relay terminal 23 or the connector terminal 31 can be adjusted depending on the length, thickness and width of the elastic force imparting portion 617. The protrusion 613, the through hole 616 and the elastic force imparting portion 617 may be formed on a pair of inner sides 611 of the groove portion 61 as shown in Fig. 9, or may be formed on only one of the inner sides 611 of the groove portion 61 as shown in Fig. 10. In these cases, the width of the relay terminal 23 or the connector terminal 31 may be slightly larger than the width between the pair of inner sides 611 of the groove portion 61.

[0051] Furthermore, in the case where the through hole 616 and the elastic force imparting portion 617 are formed, the conductor layer 62A may be formed on the entire pair of inner sides 611 of the groove portion 61. Specifically, the conductor layer 62A is provided on the surface around the through hole 616, the surface of the elastic force imparting portion 617, and the entire periphery of the groove portion 61, and is electrically connected to electronic components and the like arranged on the circuit board 6 by the conductor layer 62B.

[0052] Other configurations, functions, and effects of the ignition coil 1 of this embodiment are similar to those of embodiment 1. Also, in this embodiment, components denoted by the same reference numerals as those in embodiment 1 are similar to those in embodiment 1.

[0053] The present invention is not limited to the above-mentioned embodiments, and further different embodiments can be configured without departing from the spirit of the present invention. For example, the groove 61 may be formed at an end portion other than the end portion 601 of the opening side F2 in the depth direction F of the circuit board 6, for example, at an end portion of the bottom side F1. The insertion of the relay terminal 23 or the connector terminal 31 into the groove 61 may be performed at an end portion other than the end portion 601 of the opening side F2 in the depth direction F of the circuit board 6.

[0054] In addition, the present invention includes various modified examples, modified examples within the scope of equivalents, etc. Furthermore, various combinations of components, forms, etc. envisioned from the present invention are also included in the technical spirit of the present invention. [Explanation of symbols]

[0055] 1 Ignition coil 21 Primary coil 22 Secondary coil 23 Relay terminal 3 Connector 31 Connector terminal 5 Coil case 6 Circuit Board 61 Groove 62A, 62B Conductor layer

Claims

1. A primary coil (21) and a secondary coil (22), A circuit board (6) on which an electronic circuit is formed; a coil case (5) in which the primary coil, the secondary coil, and the circuit board are housed; a connector (3) disposed in the coil case and provided with a plurality of connector terminals (31); A plurality of grooves (61) are formed at either end of the circuit board, the grooves having conductor layers (62A) on their inner surfaces (611), An ignition coil (1) for an internal combustion engine, wherein at least one of the coil end (211) of the primary coil, the coil end (221) of the secondary coil, a relay terminal (23) connected to the coil end of the primary coil, and a relay terminal (23) connected to the coil end of the secondary coil, as well as at least one of the plurality of connector terminals, are inserted into the groove portion and electrically connected to the conductor layer.

2. The groove portion is formed in a plurality of rows in a width direction (B) of the circuit board at an end (601) located on the side of the opening (53) of the coil case, the groove portion penetrating the circuit board in a thickness direction (T) of the circuit board, the coil end portion or the relay terminal is inserted into the groove portion from one side in the plate thickness direction, 2. The ignition coil for an internal combustion engine according to claim 1, wherein the connector terminal is inserted into the groove from the other side in the plate thickness direction.

3. The relay terminal and the connector terminal have a flat cross section, a thickness direction of the relay terminal and the connector terminal is oriented in the width direction of the circuit board, 3. An ignition coil for an internal combustion engine as described in claim 2, wherein the surfaces of both sides in the thickness direction of the relay terminal and the connector terminal are in contact with the conductor layers provided on a pair of inner surfaces located on both sides in the width direction of the groove portion.

4. A protrusion (613) is formed in a part of a depth direction (F) perpendicular to both the plate thickness direction and the width direction of the circuit board in at least one of the pair of inner surfaces of the groove portion, the protrusion (613) protruding so as to reduce the width in the width direction between the pair of inner surfaces, 4. The ignition coil for an internal combustion engine according to claim 3, wherein a surface in the thickness direction of at least one of the relay terminal and the connector terminal is in contact with the conductor layer provided on the protruding portion.

5. 5. An ignition coil for an internal combustion engine as described in claim 3 or 4, wherein a convex portion (614) that contacts the inner surface of the groove portion is formed on at least one surface in the thickness direction of at least one of the relay terminal and the connector terminal.

6. 5. An ignition coil for an internal combustion engine as described in claim 4, wherein a through hole (616) is formed in the circuit board at a position adjacent to the outside of the protrusion in the width direction, the through hole penetrating the circuit board in the plate thickness direction and for imparting an elastic force to the protrusion.

7. 7. The ignition coil for an internal combustion engine according to claim 1, wherein the circuit board has a function of energizing and cutting off energization to the primary coil by a switching signal sent from the outside using the connector terminal of the connector.

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