Ignition coil and ignition device

Abstract

To provide an ignition coil for an internal combustion engine and an ignition device capable of efficiently radiating heat generated from two primary coils to the outside of a case.SOLUTION: An ignition coil 104 housed in a case has a first through iron core 61, a second through iron core 62, an outer peripheral iron core 6 on one end side, and an outer peripheral iron core 6 on the other end side. The first penetration iron core 61 penetrates the inside of the first primary coil and the inside of the first secondary coil L12. The second penetration iron core 62 penetrates the inside of the second primary coil and the inside of the second secondary coil L22. The one end side outer peripheral iron core 63 connects one end of the first through iron core 61 and one end of the second through iron core 62. The other end side outer peripheral iron core 64 connects the other end of the first through iron core 61 and the other end of the second through iron core 62. The case has a concave shape that is open upward and filled with the mold resin. The upper end portion of the one end side outer peripheral iron core 63 and the upper end portion of the other end side outer peripheral iron core 64 are located above the first secondary coil L12 and the second secondary coil L22, respectively.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Conventionally, in internal combustion engines of automobiles and the like, lean combustion, in which a lean fuel with a lower air-fuel ratio than the stoichiometric air-fuel ratio is burned, has been used to improve fuel efficiency in response to resource depletion. Furthermore, the use of carbon-free ammonia as a fuel has also been considered in order to realize a decarbonized society in response to global warming. However, these fuels are generally less flammable than gasoline and require high energy for ignition. Therefore, various ignition methods have been considered to effectively burn these fuels, such as multiple ignition methods in which a spark plug discharges multiple times in succession, and dual coil offset (DCO) ignition methods in which two ignition coils connected to a single spark plug are alternately operated to continuously discharge the spark plug. For example, Patent Documents 1 and 2 disclose ignition devices for internal combustion engines that employ DCO ignition methods. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-129464 [Patent Document 2] Patent Application No. 2024-079877 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, a drive circuit (2) for generating a spark discharge in an ignition plug (1) includes two coil pairs (11, 12). The first coil pair (11) is formed by winding a primary coil (11a) and a secondary coil (11b) around an iron core (10). The second coil pair (12) is formed by winding a primary coil (12a) and a secondary coil (12b) around the iron core (10) (see paragraph 0017, Figures 1-2). The iron core (10) is formed by laminating multiple thin iron plates together without any gaps. A magnetic flux (Φ1) generated by energizing the primary coil (11a) of the first coil pair (11) and a magnetic flux (Φ2) generated by energizing the primary coil (12a) of the second coil pair (12) both pass through a common portion (11c) of the iron core (10) (see paragraph 0018).

[0005] In Patent Document 2, an ignition coil (104) connected to a spark plug (101) includes a first coil set (40), a second coil set (50), and an iron core (60) (paragraph 0025). The iron core (60) is configured by combining a first iron core (61), a second iron core (62), a one-end connecting iron core (63), and an other-end connecting iron core (64). The first iron core (61) penetrates through the inside of the first primary coil (L11) and the inside of the first secondary coil (L12) of the first coil set (40). The second iron core (62) penetrates through the inside of the second primary coil (L21) and the inside of the second secondary coil (L22) of the second coil set (50) (paragraph 0031). The one-end connection core (63) connects one end (611) of the first core (61) to one end (621) of the second core (62). The other-end connection core (64) connects the other end (612) of the first core (61) to the other end (622) of the second core (62) (paragraph 0032). This forms a single annular closed magnetic circuit in which the first core (61), one-end connection core (63), second core (62), and other-end connection core (64) are connected in this order.

[0006] As described in paragraph 0025 of Patent Document 2, the two coil sets and the iron core connected to the spark plug are housed together with other components in a case (not shown). Furthermore, the gaps within the case are filled with a thermosetting molding resin to securely insulate the components. For example, epoxy resin is used as the molding resin. Epoxy resin has a low thermal conductivity of approximately 0.1 to 0.8 W / mK. Meanwhile, the thermal conductivity of the electromagnetic steel sheet (35A300) that constitutes the iron core is approximately 20 W / mK.

[0007] Furthermore, when the ignition coil is driven, current flows through each primary coil of each coil set, which is enclosed in the molded resin inside the case, each time it is charged. Therefore, repeated charging of each primary coil can cause heat generated by each primary coil to remain inside the case, potentially leading to melting or malfunction of surrounding components. Therefore, there is room for improvement in the ignition coil structure to efficiently dissipate the heat generated by each primary coil to the outside of the case.

[0008] The object of the present invention is to provide a technology that enables efficient dissipation of heat generated from each primary coil to the outside of the case by devising a structure for an ignition coil in which two coil sets connected to an ignition plug are housed within a case. [Means for solving the problem]

[0009] In order to solve the above problems, the first invention of the present application is an ignition coil for an internal combustion engine, comprising a first primary coil, a first secondary coil, a first through core, a second primary coil, a second secondary coil, a second through core, a one-end outer core, an other-end outer core, and a case. The first primary coil comprises a first primary winding, one end of which is applied with a DC voltage and the other end of which is connected to a ground. The first secondary coil comprises a first secondary winding. The first through core passes through the inside of the first primary coil and the inside of the first secondary coil, electromagnetically coupling the first primary coil and the first secondary coil. The second primary coil comprises a second primary winding, one end of which is applied with the DC voltage and the other end of which is connected to a ground. The second secondary coil comprises a second secondary winding. The second through core passes through the inside of the second primary coil and the inside of the second secondary coil, electromagnetically coupling the second primary coil and the second secondary coil. The one-end outer core connects one end of the first through core to one end of the second through core. The other-end outer core connects the other end of the first through core to the other end of the second through core. The case has a concave shape with an opening at its upper end by opening upward, and houses the first primary coil, the first secondary coil, the first through core, the second primary coil, the second secondary coil, the second through core, the one-end outer core, and the other-end outer core. The case is filled with a thermosetting molding resin. The upper end of the one-end outer core and the upper end of the other-end outer core are located higher than the first secondary coil and the second secondary coil, respectively.

[0010] A second aspect of the present invention is the ignition coil of the first aspect, wherein an upper end portion of the one end side outer peripheral iron core and / or an upper end portion of the other end side outer peripheral iron core are exposed above an upper surface of the molding resin.

[0011] The third invention of the present application is an ignition coil of the first or second invention, further having a central core arranged between the first penetrating core and the second penetrating core, connecting the one end side outer peripheral core and the other end side outer peripheral core.

[0012] The fourth invention of the present application is an ignition coil of the third invention, wherein the center core and at least a portion of the one end side outer core and / or at least a portion of the other end side outer core are each formed from a single member.

[0013] The fifth invention of the present application is an ignition coil of the third invention, wherein the center core and at least a portion of the one end side outer core and / or at least a portion of the other end side outer core are formed from separate members.

[0014] A sixth aspect of the present invention is an ignition device comprising the ignition coil of any one of the first to fifth aspects, a power supply, a first switching element, a second switching element, a first control unit, a second control unit, and an ignition plug. The power supply applies the DC voltage to one end of the first primary coil and one end of the second primary coil. The first switching element is interposed between the other end of the first primary coil and a ground and is capable of switching between conducting and cutting off a first primary current flowing from the power supply to the first primary coil. The second switching element is interposed between the other end of the second primary coil and a ground and is capable of switching between conducting and cutting off a second primary current flowing from the power supply to the second primary coil. The first control unit controls the switching of the first switching element. The second control unit controls the switching of the second switching element. The spark plug ignites fuel by discharging in a gap based on a high voltage induced at one end of the first secondary coil and / or a high voltage induced at one end of the second secondary coil.

[0015] A seventh aspect of the present invention is an ignition device according to the sixth aspect, further comprising a high-voltage terminal held in the case below the ignition coil and interposed in a conductor connecting one end of the first secondary coil and one end of the second secondary coil to the spark plug. [Effects of the Invention]

[0016] According to the first to seventh aspects of the present invention, by arranging the upper end of the one-end side outer circumferential iron core and the upper end of the other-end side outer circumferential iron core respectively at an upper position close to the opening of the case, the heat generated from each coil can be transferred upward while suppressing the influence of the thermal resistance of the molding resin. This allows the heat generated from each coil to be dissipated upward into the case via the one-end side outer circumferential iron core and / or the other-end side outer circumferential iron core.

[0017] In particular, according to the second aspect of the present invention, heat can be more efficiently dissipated upwards in the case via the one end side outer peripheral iron core and / or the other end side outer peripheral iron core.

[0018] In particular, according to the fourth aspect of the present invention, the number of parts in the entire ignition coil including the iron core can be reduced.

[0019] In particular, according to the fifth aspect of the present invention, the center core and the one end side outer peripheral core and / or the other end side outer peripheral core can be easily formed with good yield of steel sheet material. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a block diagram schematically illustrating an operating environment of an ignition device for an internal combustion engine according to a first embodiment. [Figure 2] 1 is a perspective view of an ignition device according to a first embodiment. [Figure 3] 1 is a perspective view of an ignition device according to a first embodiment. [Figure 4] 1 is a perspective view of an ignition device according to a first embodiment. [Figure 5] FIG. 1 is a perspective view of an ignition coil according to a first embodiment. [Figure 6] 1 is a schematic vertical cross-sectional view of an ignition coil according to a first embodiment, viewed from below. [Figure 7] FIG. 10 is a perspective view of an ignition device according to a first modified example. [Figure 8] FIG. 10 is a perspective view of an ignition coil according to a second modified example. [Figure 9] FIG. 10 is a perspective view of an ignition coil according to a second embodiment. [Figure 10] FIG. 11 is a perspective view of an ignition coil according to a third modified example. [Figure 11] FIG. 11 is a perspective view of an ignition coil according to a third modified example with a resin cover removed. [Figure 12] FIG. 11 is a perspective view of an ignition coil according to a fourth modified example with a resin cover removed. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. Note that the components described in these embodiments are merely examples and are not intended to limit the scope of the present invention. Furthermore, in the drawings, the dimensions and numbers of various parts may be exaggerated or simplified as necessary for ease of understanding. Furthermore, in Fig. 5 and Figs. 8 to 12 described below, the silicon steel sheets laminated in the laminated steel sheet may be simplified.

[0022] 1. First Embodiment <1-1. Ignition device configuration> First, the configuration of an ignition device 1 for an internal combustion engine according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram schematically illustrating the operating environment of the ignition device 1 according to the first embodiment. As will be described later, the first primary coil L11 and the first secondary coil L12 of the ignition coil 104 included in the ignition device 1 are arranged in a stacked direction relative to each other, but in FIG. 1, they are illustrated as being adjacent to each other for ease of understanding. Similarly, the second primary coil L21 and the second secondary coil L22 of the ignition coil 104 are arranged in a stacked direction relative to each other, but in FIG. 1, they are illustrated as being adjacent to each other for ease of understanding.

[0023] The ignition device 1 of this embodiment is mounted on an internal combustion engine such as an SI (spark ignition) reciprocating engine mounted on a vehicle body 100 such as an automobile, and applies a high voltage to generate a spark discharge to an ignition plug 101. The ignition device 1 is provided for each of one or more cylinders of the internal combustion engine.

[0024] 1, the internal combustion engine is equipped with the ignition device 1 as well as the ignition plug 101, and the vehicle body 100 is equipped with a power supply device 102 (battery) and an ECU 103 (Engine Control Unit). In a broad sense, the ignition plug 101, the power supply device 102, and the ECU 103 can also be considered to be included in the ignition device 1.

[0025] The spark plug 101 is a device for realizing an ignition operation in a combustion chamber of an internal combustion engine. The spark plug 101 is electrically connected to one end Eg12 of a first secondary coil L12 of an ignition coil 104 (described later) via a conductor (hereinafter referred to as a "first secondary ground wire Cg12"). The spark plug 101 is interposed between one end Eg12 of the first secondary coil L12 and a ground point (ground) 151. The spark plug 101 is also electrically connected to one end Eg22 of a second secondary coil L22 of the ignition coil 104 (described later) via a conductor (hereinafter referred to as a "second secondary ground wire Cg22"). The spark plug 101 is interposed between one end Eg22 of the second secondary coil L22 and the ground point 151. That is, in the ignition device 1, one spark plug 101 is provided in common for a first coil set 40 and a second coil set 50, which will be described later.

[0026] A high voltage is induced in the first secondary coil L12 and / or the second secondary coil L22 of the ignition coil 104. When the sum of the high voltage induced at one end Eg12 of the first secondary coil L12 and the high voltage induced at one end Eg22 of the second secondary coil L22 exceeds the breakdown voltage in the gap d (see FIG. 1) between the center electrode 161 and the ground electrode 162 of the spark plug 101, a discharge occurs in the gap d, generating a spark. This ignites the fuel filled in the internal combustion engine. That is, the spark plug 101 ignites the fuel by discharging in the gap d based on the high voltage induced at one end Eg12 of the first secondary coil L12 and / or the high voltage induced at one end Eg22 of the second secondary coil L22.

[0027] The first secondary ground wire Cg12 and the second secondary ground wire Cg22 join on their way to the spark plug 101 to form the "secondary ground wire Cg20." The spark plug 101 is inserted in the secondary ground wire Cg20. Furthermore, a high-voltage terminal HG is provided on the front side of the spark plug 101 (the side opposite the ground point 151). That is, the high-voltage terminal HG is interposed in the secondary ground wire Cg20, which is a conductor connecting one end Eg12 of the first secondary coil L12 and one end Eg22 of the second secondary coil L22 to the spark plug 101. The high-voltage output of the first secondary coil L12 and the high-voltage output of the second secondary coil L22 are transmitted to the spark plug 101 via the high-voltage terminal HG.

[0028] The power supply device 102 is a storage battery capable of charging and discharging DC power. In this embodiment, the power supply device 102 is electrically connected to a first primary coil L11, a first secondary coil L12, a second primary coil L21, and a second secondary coil L22 of an ignition coil 104 (described later) via conductors (hereinafter referred to as "power lines 150"). The power supply device 102 applies a DC voltage to one end Ep11 of the first primary coil L11, the other end Ep12 of the first secondary coil L12, one end Ep21 of the second primary coil L21, and the other end Ep22 of the second secondary coil L22 of the ignition coil 104 via the power line 150. However, as described later, a first diode 131 and a second diode 132 are provided to prevent current from flowing from the power supply device 102 to the first secondary coil L12 and the second secondary coil L22.

[0029] The ECU 103 is an existing computer that comprehensively controls the operation of the transmission and engine of the vehicle body 100 .

[0030] FIG. 2 is a perspective view of the ignition device 1 according to this embodiment. FIG. 3 is a perspective view of the ignition device 1 according to this embodiment, viewed from a different direction than that of FIG. 2. FIG. 4 is a perspective view of the ignition device 1 of FIG. 3 in a state in which a resin part 108, which will be described later, is not shown. However, in FIG. 4, a resin surface 109, which is the upper surface of the resin part 108, is illustrated by a dashed line. Note that in FIG. 2 to FIG. 5, which will be described later, and FIGS. 7 to 10, which will be described later, the "vertical direction," "vertically upward," and "vertically downward" are defined for ease of explanation, but the orientation in which the ignition device 1 is disposed during manufacture and use is not limited to these.

[0031] 1 to 4, the ignition device 1 includes an ignition coil 104, a first igniter 105, a second igniter 106, a case 107, a resin part 108, a first diode 131, and a second diode 132. In a broad sense, the case 107 and the resin part 108 can also be considered to be included in the ignition coil 104.

[0032] FIG. 5 is a perspective view of the ignition coil 104 according to this embodiment. FIG. 6 is a schematic vertical cross-sectional view of the ignition coil 104 as viewed from below. In FIG. 6, components such as the power supply device 102 connected to the ignition coil 104 are indicated by two-dot chain lines. As shown in FIGS. 1 and 4 to 6, the ignition coil 104 includes a first coil set 40, a second coil set 50, and an iron core 60. The first coil set 40 and the second coil set 50 are arranged side by side in the horizontal direction. As will be described later, the first coil set 40 and the second coil set 50 are connected in parallel to one ignition plug 101. The first coil set 40 includes a first bobbin 41, a first primary coil L11, and a first secondary coil L12. The second coil set 50 has a second bobbin 51, a second primary coil L21, and a second secondary coil L22. As will be described in detail later, the ignition coil 104 is integrally housed in a case 107 together with a first igniter 105 and a second igniter 106.

[0033] In the following description of the ignition coil 104, a direction parallel to the first center axis Bc1 of the first bobbin 41 is referred to as the "first axial direction," a direction perpendicular to the first center axis Bc1 is referred to as the "first radial direction," and a direction along an arc centered on the first center axis Bc1 is referred to as the "first circumferential direction." Also, a direction parallel to the second center axis Bc2 of the second bobbin 51 is referred to as the "second axial direction," a direction perpendicular to the second center axis Bc2 is referred to as the "second radial direction," and a direction along an arc centered on the second center axis Bc2 is referred to as the "second circumferential direction." Also, the term "parallel direction" includes a direction that is approximately parallel, and the term "orthogonal direction" includes a direction that is approximately perpendicular. In this embodiment, the first center axis Bc1 and the second center axis Bc2 are approximately parallel and horizontal.

[0034] The first bobbin 41 includes a first primary bobbin 411 and a first secondary bobbin 412 that are connectable to each other. The first primary bobbin 411 and the first secondary bobbin 412 each extend cylindrically along a first central axis Bc1. The first secondary bobbin 412 is disposed on the outside of the first primary bobbin 411 in a first radial direction. The first primary bobbin 411 and the first secondary bobbin 412 are made of, for example, resin. The first primary coil L11 is formed by winding a conducting wire (hereinafter referred to as the "first primary winding 811") around the outer circumferential surface of the first primary bobbin 411 in a first circumferential direction around the first central axis Bc1. That is, the first primary coil L11 is made of the first primary winding 811.

[0035] After the formation of the first primary coil L11 is completed, the first secondary bobbin 412 is disposed so as to cover the outer peripheral surface of the first primary coil L11 and is connected to the first primary bobbin 411. Then, a conductor wire separate from the first primary winding 811 (hereinafter referred to as the "first secondary winding 812") is wound around the outer peripheral surface of the first secondary bobbin 412 in a first circumferential direction centered on the first central axis Bc1, thereby forming the first secondary coil L12. That is, the first secondary coil L12 is made of the first secondary winding 812. By arranging the first primary coil L11 and the first secondary coil L12 so as to be stacked on top of each other in this manner, the entire ignition coil 104 including these coils can be made more compact. However, the first primary coil L11 and the first secondary coil L12 do not necessarily have to be wound while being stacked on top of each other in this manner, but may also be arranged adjacent to each other in the first axial direction, for example.

[0036] The second bobbin 51 includes a second primary bobbin 511 and a second secondary bobbin 512 that are connectable to each other. The second primary bobbin 511 and the second secondary bobbin 512 each extend cylindrically along a second central axis Bc2. The second secondary bobbin 512 is disposed on the outer side of the second primary bobbin 511 in the second radial direction. The second primary bobbin 511 and the second secondary bobbin 512 are made of, for example, resin. The second primary coil L21 is formed by winding a conducting wire (hereinafter referred to as the "second primary winding 821") around the outer circumferential surface of the second primary bobbin 511 in a second circumferential direction centered on the second central axis Bc2. That is, the second primary coil L21 is made of the second primary winding 821.

[0037] After the formation of the second primary coil L21 is completed, the second secondary bobbin 512 is disposed so as to cover the outer circumferential surface of the second primary coil L21 and is connected to the second primary bobbin 511. Then, a conductor wire separate from the second primary winding 821 (hereinafter referred to as the "second secondary winding 822") is wound around the outer circumferential surface of the second secondary bobbin 512 in a second circumferential direction centered on the second central axis Bc2, thereby forming the second secondary coil L22. That is, the second secondary coil L22 is made of the second secondary winding 822. By arranging the second primary coil L21 and the second secondary coil L22 so as to be stacked on top of each other in this manner, the entire ignition coil 104 including these coils can be made more compact. However, the second primary coil L21 and the second secondary coil L22 do not necessarily have to be wound while being stacked on top of each other in this manner, but may also be arranged adjacent to each other in the second axial direction, for example.

[0038] The core 60 of this embodiment has a structure in which a first through core 61, a second through core 62, a one-end outer periphery core 63, and an other-end outer periphery core 64 are combined. The first through core 61, the second through core 62, the one-end outer periphery core 63, and the other-end outer periphery core 64 are each formed, for example, from a laminated steel plate in which silicon steel plates are stacked. Note that a silicon steel plate is generally an electromagnetic steel plate formed by rolling heat-treated steel in which a few percent of silicon is mixed into iron. However, steel plates other than silicon steel plates may also be used for the first through core 61, the second through core 62, the one-end outer periphery core 63, and the other-end outer periphery core 64. Furthermore, each of the first through core 61, the second through core 62, the one end side outer peripheral core 63, and the other end side outer peripheral core 64 may be a powder core formed from a sintered material.

[0039] The first penetrating core 61 extends substantially horizontally and in a columnar shape along the first center axis Bc1. The first penetrating core 61 is inserted into a space 410 on the inside in the first radial direction of the first primary bobbin 411. That is, the first penetrating core 61 passes through the inside of the first primary coil L11 and the inside of the first secondary coil L12. The second penetrating core 62 extends substantially horizontally and in a columnar shape along the second center axis Bc2. The second penetrating core 62 is inserted into a space 510 on the inside in the second radial direction of the second primary bobbin 511. That is, the second penetrating core 62 passes through the inside of the second primary coil L21 and the inside of the second secondary coil L22.

[0040] In this embodiment, the one-end outer periphery core 63 and the other-end outer periphery core 64 each extend substantially horizontally and columnarly in a direction substantially perpendicular to the first center axis Bc1 and the second center axis Bc2. More specifically, as shown in FIGS. 5 and 6 , the one-end outer periphery core 63 is placed above one end 611 of the first through core 61 and above one end 621 of the second through core 62. As a result, the one-end outer periphery core 63 connects the one end 611 of the first through core 61 to the one end 621 of the second through core 62. Furthermore, the other-end outer periphery core 64 is placed above the other end 612 of the first through core 61 and above the other end 622 of the second through core 62. As a result, the other-end outer periphery core 64 connects the other end 612 of the first through core 61 to the other end 622 of the second through core 62.

[0041] This forms a ring-shaped closed magnetic circuit that connects the first through core 61, the one-end outer peripheral core 63, the second through core 62, and the other-end outer peripheral core 64 in this order. The first through core 61 electromagnetically couples the first primary coil L11 and the first secondary coil L12. The second through core 62 electromagnetically couples the second primary coil L21 and the second secondary coil L22.

[0042] It is desirable that the silicon steel plates are laminated in a direction perpendicular to the direction of magnetic flux in the closed magnetic circuit in each of the first through core 61, the second through core 62, the one end side outer periphery core 63, and the other end side outer periphery core 64. However, the silicon steel plates may be laminated in a direction different from the direction perpendicular to the direction of magnetic flux in the closed magnetic circuit in each of the first through core 61, the second through core 62, the one end side outer periphery core 63, and the other end side outer periphery core 64.

[0043] Furthermore, due to the space required for arranging the ignition coil 104 within the case 107, the first penetrating core 61 and the second penetrating core 62 each extend in a columnar shape in a substantially horizontal direction when the ignition coil 104 is housed in the case 107. Therefore, when housed in the case 107, the first penetrating core 61 is located farther from an opening 120 (described later) of the case 107 than the upper end of the first primary coil L11. Similarly, when housed in the case 107, the second penetrating core 62 is located farther from the opening 120 of the case 107 than the upper end of the first secondary coil L12. Furthermore, the first penetrating core 61 and the second penetrating core 62 are also disposed apart from the side surfaces of the case 107. Meanwhile, the upper ends of the one-end outer peripheral core 63 and the other-end outer peripheral core 64 are located higher than the first secondary coil L12 and the second secondary coil L22, respectively. The effect of such a structure will be described in detail later.

[0044] As described above, one end Ep11 of the first primary coil L11 is connected to the power line 150, which is a conductor extending from the power supply device 102. The other end Eg11 of the first primary coil L11 is connected to the ground 152 via the first igniter 105, which will be described later. Under the control of the first igniter 105, a low DC voltage from the power supply device 102 is applied to the one end Ep11 of the first primary coil L11, and a gradually increasing first primary current begins to flow through the first primary coil L11. Furthermore, in this embodiment, when a DC voltage from the power supply device 102 is applied to the first primary coil L11, an electromagnetic flux is generated in the first through core 61 from the other end 612 to the one end 611.

[0045] The wire diameter of the first secondary winding 812 is smaller than that of the first primary winding 811. The number of turns of the first secondary winding 812 in the first secondary coil L12 is greater (for example, about 100 times or more) than the number of turns of the first primary winding 811 in the first primary coil L11. As a result, when the first primary current is interrupted, the ignition coil 104 boosts the low-voltage DC power supplied from the power supply device 102 to, for example, several thousand to several tens of thousands of volts. That is, a high voltage is induced in the first secondary coil L12. The first secondary coil L12 then supplies the induced high-voltage power to the spark plug 101 via the secondary-side ground wires Cg12 and Cg20. This generates an electric spark in the spark plug 101, igniting the fuel.

[0046] As shown in FIG. 1, a first diode 131 is connected in series with the first secondary coil L12 to the first secondary-side ground wire Cg12. The first diode 131 has a forward direction from one end Eg12 to the other end Ep12 of the first secondary coil L12. This prevents an induced current caused by a voltage induced in the first secondary coil L12 by the first primary current, which gradually increases when the first primary coil L11 is energized, from flowing in the reverse direction to the ignition plug 101. As described above, the power supply line 150, which is a conductor extending from the power supply device 102, is connected to the other end Ep12 of the first secondary coil L12.

[0047] As described above, one end Ep21 of the second primary coil L21 is connected to the power line 150, which is a conductor extending from the power supply device 102. The other end Eg21 of the second primary coil L21 is connected to the ground point 152 via the second igniter 106, which will be described later. Under the control of the second igniter 106, a low DC voltage from the power supply device 102 is applied to one end Ep21 of the second primary coil L21, and a gradually increasing second primary current begins to flow through the second primary coil L21. In this embodiment, when a DC voltage from the power supply device 102 is applied to the second primary coil L21, an electromagnetic flux is generated in the second through core 62 from the other end 622 to the one end 621.

[0048] The wire diameter of the second secondary winding 822 is smaller than that of the second primary winding 821. The number of turns of the second secondary winding 822 in the second secondary coil L22 is greater than the number of turns of the second primary winding 821 in the second primary coil L21 (for example, about 100 times or more). As a result, when the second primary current is interrupted, the ignition coil 104 boosts the low-voltage DC power supplied from the power supply device 102 to, for example, several thousand to several tens of thousands of volts. That is, a high voltage is induced in the second secondary coil L22. The second secondary coil L22 then supplies the induced high-voltage power to the spark plug 101 via the secondary-side ground wires Cg22 and Cg20. This allows the electric spark generated in the spark plug 101 to be maintained for a longer period of time.

[0049] As shown in FIG. 1, a second diode 132 is connected in series with the second secondary coil L22 to the second secondary-side ground wire Cg22. The second diode 132 has a forward direction from one end Eg22 to the other end Ep22 of the second secondary coil L22. This prevents an induced current caused by a voltage induced in the second secondary coil L22 by the second primary current, which gradually increases when the second primary coil L21 is energized, from flowing in the reverse direction to the spark plug 101. As described above, the other end Ep22 of the second secondary coil L22 is connected to the power supply line 150, which is a conductor extending from the power supply device 102.

[0050] As described above, in this embodiment, in one ignition coil 104, the first through core 61 inserted inside the first coil set 40 and the second through core 62 inserted inside the second coil set 50 are connected to each other via the one-end outer core 63 and the other-end outer core 64, thereby forming one closed magnetic circuit. This allows the entire ignition coil 104, including the core 60, to be more compact than when a closed magnetic circuit is formed for each coil set 40, 50. As a result, the ignition device 1 including the ignition coil 104 can be more easily mounted in an internal combustion engine. Furthermore, the reduction in the number of parts leads to a reduction in the manufacturing cost of the entire device.

[0051] The first igniter 105 is a semiconductor device connected to the first primary coil L11 and controls the current flowing through the first primary coil L11. The first igniter 105 is electrically connected to the ECU 103 and receives a signal (hereinafter referred to as a "first EST signal S1") from the ECU 103. The first igniter 105 includes a first switching element 71 and a first drive IC 72. The first igniter 105 may be integrated with the electronic circuit of the ECU 103.

[0052] The first switching element 71 may be, for example, an insulated gate bipolar transistor (IGBT). The first switching element 71 is interposed between the other end Eg11 of the first primary coil L11 and a ground point 152. A collector (C) of the first switching element 71 is connected to the other end Eg11 of the first primary coil L11. An emitter (E) of the first switching element 71 is connected to the ground point 152. A gate (G) of the first switching element 71 is connected to the first driving IC 72.

[0053] This allows the first switching element 71 to switch between passing and blocking the first primary current flowing from the power supply device 102 to the first primary coil L11. When the first switching element 71 is in a closed state, the first primary current flows from the power supply device 102 to the first primary coil L11. When the first switching element 71 is in an open state, the first primary current flowing to the first primary coil L11 is blocked. However, other types of transistors may be used for the first switching element 71.

[0054] The first drive IC 72 controls the switching of the first switching element 71 based on a first EST signal S1 received from the ECU 103. The first drive IC 72 corresponds to a "first control unit" of the present invention. The first drive IC 72 has a logic device connected to the first switching element 71. The logic device includes, for example, a logic circuit, a processor, a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), or an application-specific integrated circuit (ASIC). The logic device performs arithmetic processing to operate the ignition device 1 and ignite the spark plug 101.

[0055] The second igniter 106 is a semiconductor device connected to the second primary coil L21 and controls the current flowing through the second primary coil L21. The second igniter 106 is electrically connected to the ECU 103 and receives a signal (hereinafter referred to as a "second EST signal S2") from the ECU 103. The second igniter 106 includes a second switching element 73 and a second drive IC 74. The second igniter 106 may be integrated with the electronic circuit of the ECU 103.

[0056] The second switching element 73 is, for example, an insulated gate bipolar transistor (IGBT). The second switching element 73 is interposed between the other end Eg21 of the second primary coil L21 and the ground point 152. C (collector) of the second switching element 73 is connected to the other end Eg21 of the second primary coil L21. E (emitter) of the second switching element 73 is connected to the ground point 152. G (gate) of the second switching element 73 is connected to the second drive IC 74.

[0057] This allows the second switching element 73 to switch between passing and blocking the second primary current flowing from the power supply device 102 to the second primary coil L21. When the second switching element 73 is in a closed state, the second primary current flows from the power supply device 102 to the second primary coil L21. When the second switching element 73 is in an open state, the second primary current flowing to the second primary coil L21 is blocked. However, other types of transistors may be used for the second switching element 73.

[0058] The second drive IC 74 controls the switching of the second switching element 73 based on the second EST signal S2 received from the ECU 103. The second drive IC 74 corresponds to the "second control unit" of the present invention. The second drive IC 74 has a logic device connected to the second switching element 73. The logic device includes, for example, a logic circuit, a processor, a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), or an application-specific integrated circuit (ASIC). The logic device operates the ignition device 1 to perform arithmetic processing for maintaining the electric spark generated in the spark plug 101 for a longer period of time.

[0059] The case 107 is a container made of insulating resin. The case 107 forms the outer shape of the ignition device 1 and has a generally concave shape that opens vertically upward. This forms an opening 120 at the upper end of the case 107. The case 107 houses components including the ignition coil 104, the first igniter 105, and the second igniter 106. That is, the case 107 houses the first primary coil L11, the first secondary coil L12, the first through core 61, the second primary coil L21, the second secondary coil L22, the second through core 62, the one-end outer circumferential core 63, the other-end outer circumferential core 64, the first igniter 105, and the second igniter 106. The case 107 also has a main accommodating portion 91, a first connector portion 921, a second connector portion 922, fixing portions 931 and 932, and a lower accommodating portion 94.

[0060] The main accommodating portion 91 has a concave shape that opens vertically upward. The opening 120 is formed at the upper end of the main accommodating portion 91. Hereinafter, the space inside the main accommodating portion 91 will be referred to as the "internal space 910." The internal space 910 accommodates the ignition coil 104, the first igniter 105, and the second igniter 106. The ignition coil 104 is accommodated in the internal space 910 with the first axial direction of the first coil set 40 and the second axial direction of the second coil set 50 oriented horizontally. The first igniter 105 is disposed on one side of the first coil set 40 in the first axial direction. The second igniter 106 is disposed on one side of the second coil set 50 in the second axial direction. Moreover, around the ignition coil 104, the first igniter 105, and the second igniter 106, conducting wires and the like connected to each part are appropriately arranged.

[0061] In the manufacturing process of ignition device 1, ignition coil 104, first igniter 105, second igniter 106, and the conductors connected thereto are arranged in internal space 910, and then a thermosetting molding resin is poured into case 107 to insulate and secure these components. Specifically, the thermosetting molding resin is filled into case 107. For example, epoxy resin is used as the molding resin. The molding resin is filled up to the vicinity of opening 120 in case 107. After the molding resin hardens, resin portion 108 is formed, filling the gap within case 107. As a result, each component, including ignition coil 104, first igniter 105, and second igniter 106, is held in an appropriate position within internal space 910.

[0062] In this embodiment, the upper end of the one-end outer periphery core 63 and the upper end of the other-end outer periphery core 64 are lined with corners of the silicon steel plates (laminated steel plates) that make up the one-end outer periphery core 63 and the other-end outer periphery core 64, respectively. Therefore, there is concern that these corners could become the source of cracks in the molded resin. Therefore, as shown in FIG. 5 , resin covers 66 are fitted in contact with the upper surfaces of the one-end outer periphery core 63 and the other-end outer periphery core 64 so as to cover them. This protects the corners of the silicon steel plates (laminated steel plates) at the upper end of the one-end outer periphery core 63 and the other-end outer periphery core 64 with the resin covers 66, thereby preventing cracks from occurring in the molded resin.

[0063] As will be described in detail later, when the ignition coil 104 is driven, current repeatedly flows through the primary coils L11 and L21 of each coil set 40 and 50, which are surrounded by the resin portion 108 inside the case 107. This causes repeated heat generation, primarily from each primary coil L11 and L21. If this heat were to remain inside the case 107, it could potentially affect surrounding components. Therefore, it is necessary to remove the generated heat and dissipate it to the outside of the case 107. However, the thermal conductivity of the epoxy resin forming the resin portion 108 surrounding each coil set 40 and 50 is low, approximately 0.1 to 0.8 W / mK. Therefore, it is difficult to dissipate the heat generated from each primary coil L11, L21, etc., to the outside of the case 107 via the resin portion 108.

[0064] Furthermore, although the thermal conductivity of the electromagnetic steel sheet (35A300) constituting the first penetrating core 61 that penetrates the inside of the first primary coil L11 and the second penetrating core 62 that penetrates the inside of the second primary coil L21 is a large value of about 20 W / mK, these are arranged at a position spaced downward from the opening 120 of the case 107. Furthermore, as described above, the first penetrating core 61 and the second penetrating core 62 are also arranged at a position spaced apart from the side surface of the case 107.

[0065] Therefore, in the present invention, the upper end of the one-end outer periphery core 63 and the upper end of the other-end outer periphery core 64, which connect the first penetrating core 61 and the second penetrating core 62, are positioned higher than the first secondary coil L12 and the second secondary coil L22, respectively. That is, the upper end of the one-end outer periphery core 63 and the upper end of the other-end outer periphery core 64 are each positioned higher, near the resin surface 109, which is the upper surface of the resin part 108. In other words, the upper end of the one-end outer periphery core 63 and the upper end of the other-end outer periphery core 64 are each positioned higher, near the opening 120 of the case 107.

[0066] This allows the heat generated from the primary coils L11, L21, etc. of each coil set 40, 50 to be transferred further upward while suppressing the influence of the thermal resistance of the molded resin that constitutes the resin portion 108. As a result, the heat generated from the primary coils L11, L21, etc. of each coil set 40, 50 can be dissipated upward in the case 107 via the one-end outer peripheral iron core 63 and the other-end outer peripheral iron core 64.

[0067] 7, the upper end of the one-end-side outer circumferential core 63 and / or the upper end of the other-end-side outer circumferential core 64 may be exposed above the resin surface 109. That is, the upper end of the one-end-side outer circumferential core 63 and / or the upper end of the other-end-side outer circumferential core 64 may be exposed above the upper surface of the molded resin that forms the resin portion 108. This allows heat generated from the primary coils L11, L21, etc. of each coil set 40, 50 to be more efficiently dissipated above the case 107 via the one-end-side outer circumferential core 63 and the other-end-side outer circumferential core 64.

[0068] 8, the one-end outer circumferential core 63 may be provided adjacent to one end face in the first axial direction of the first penetrating core 61 and adjacent to one end face in the second axial direction of the second penetrating core 62. The other-end outer circumferential core 64 may be provided adjacent to the other end face in the first axial direction of the first penetrating core 61 and adjacent to the other end face in the second axial direction of the second penetrating core 62. Even in this case, the one-end outer circumferential core 63 and the other-end outer circumferential core 64 can each connect the first penetrating core 61 and the second penetrating core 62.

[0069] In the second modified example, as in the present embodiment, the upper end of the one-end outer circumferential core 63 and the upper end of the other-end outer circumferential core 64 are positioned higher than the first secondary coil L12 and the second secondary coil L22, respectively. That is, the upper end of the one-end outer circumferential core 63 and the upper end of the other-end outer circumferential core 64 are positioned higher and closer to the resin surface 109 and the opening 120 of the case 107, respectively. This allows heat generated from the primary coils L11, L21, etc. of each coil set 40, 50 to be transferred upward via the one-end outer circumferential core 63 and the other-end outer circumferential core 64 and dissipated above the case 107 while suppressing the influence of the thermal resistance of the molded resin that constitutes the resin portion 108.

[0070] As shown in FIGS. 2 to 4 , a first connector 921 and a second connector 922 are provided side by side in the horizontal direction on a side of the main housing 91 of the case 107. The first connector 921 is provided on one side of the first igniter 105 in the first axial direction. The conductors connected to the first igniter 105 and the power supply line 150 extending from the first primary winding 811 are drawn to the outside of the case 107 via the first connector 921 and connected to the ECU 103, the power supply device 102, etc. The second connector 922 is provided on one side of the second igniter 106 in the second axial direction. The conductors connected to the second igniter 106 and the power supply line 150 extending from the second primary winding 821 are drawn to the outside of the case 107 via the second connector 922 and connected to the ECU 103, the power supply device 102, etc.

[0071] Furthermore, fixing portions 931 and 932 are provided on the sides of main housing portion 91 of case 107 at positions different from the positions where first connector portion 921 and second connector portion 922 are provided. Fixing portions 931 and 932 are formed at positions facing each other. Fixing portions 931 and 932 are portions that protrude from main housing portion 91 in a substantially triangular prism shape and are used to attach and fix ignition device 1 to the engine block.

[0072] The lower accommodating portion 94 is a member that extends vertically in a cylindrical shape. The upper end of the lower accommodating portion 94 is fixed near the center of the bottom of the main accommodating portion 91. A high-voltage terminal HG is fixed in the space inside the lower accommodating portion 94. That is, the high-voltage terminal HG is held by the case 107 below the ignition coil 104. A hole 915 that penetrates the bottom of the main accommodating portion 91 is provided near the center of the bottom of the main accommodating portion 91. The space inside the lower accommodating portion 94 communicates with the internal space 910 of the main accommodating portion 91 via the hole 915. The secondary-side ground wire Cg20 is inserted into the lower accommodating portion 94 through the hole 915 and connected to the high-voltage terminal HG.

[0073] <1-2. Operation of the ignition device> Next, the operation of the ignition device 1 will be described.

[0074] When the ignition device 1 is operated, first, at time t0, the signal level of the first EST signal S1 transmitted from the ECU 103 to the first drive IC 72 is changed from L to H. Then, the first drive IC 72 switches the first switching element 71 from an open state to a closed state based on the first EST signal S1. This causes a low DC voltage from the power supply 102 to be applied to one end Ep11 of the first primary coil L11. A first primary current then flows through the first primary winding 811 that forms the first primary coil L11, generating a magnetomotive force in the first primary coil L11. Furthermore, an electromagnetic flux φa1 is generated in the first through core 61, flowing from the other end 612 to the one end 611, and a magnetic field corresponding to the electromagnetic flux φa1 acts on the core 60.

[0075] Next, at time t1, which is later than time t0, the signal level of the first EST signal S1 transmitted from the ECU 103 to the first drive IC 72 is changed from H to L, and the signal level of the second EST signal S2 transmitted from the ECU 103 to the second drive IC 74 is changed from L to H. The first drive IC 72 then switches the first switching element 71 from closed to open, interrupting the primary current (first primary current) flowing from the power supply 102 to the first primary coil L11. As a result, in the first secondary coil L12, which is electromagnetically coupled to the first primary coil L11 via the iron core 60, mutual induction generates an interruption magnetic flux φs1 in the opposite direction to the above-described conduction magnetic flux φa1, and a large induced electromotive force is induced. At this time, the voltage applied to one end Eg12 of the first secondary coil L12 ranges from minus several thousand volts to several tens of thousands of volts relative to the ground point 152. As a result, an electric spark is generated in the spark plug 101 connected to one end Eg12 of the first secondary coil L12 to ignite the fuel, and an induced current (first secondary current) flows through the first secondary coil L12.

[0076] At time t1, the second driving IC 74 switches the second switching element 73 from the open state to the closed state. This applies a low DC voltage from the power supply 102 to one end Ep21 of the second primary coil L21. A second primary current flows through the second primary winding 821 that forms the second primary coil L21, generating a magnetomotive force in the second primary coil L21. An electromagnetic flux φb1 is generated in the second through core 62, traveling from the other end 622 to the one end 621. A magnetic field corresponding to the electromagnetic flux φb1 acts on the core 60. The direction of the electromagnetic flux φb1 is the same as the blocking magnetic flux φs1. This amplifies the magnetic flux generated in the closed magnetic path of the core 60. This increases the current and ignition energy supplied to the spark plug 101.

[0077] Furthermore, at time t2, which is later than time t1, the signal level of the second EST signal S2 transmitted from the ECU 103 to the second drive IC 74 is changed from H to L, and the signal level of the first EST signal S1 transmitted from the ECU 103 to the first drive IC 72 is changed from L to H. The second drive IC 74 then switches the second switching element 73 from closed to open, interrupting the primary current (second primary current) flowing from the power supply 102 to the second primary coil L21. As a result, in the second secondary coil L22, which is electromagnetically coupled to the second primary coil L21 via the iron core 60, mutual induction generates a blocking magnetic flux φs2 in the opposite direction to the conducting magnetic flux φb1, and a large induced electromotive force is induced. At this time, the voltage applied to one end Eg22 of the second secondary coil L22 ranges from minus several thousand volts to several tens of thousands of volts relative to the ground point 152. As a result, the electric spark and flame generated around the spark plug 101 connected to one end Eg22 of the second secondary coil L22 can be maintained, and an induced current (second secondary current) flows in the second secondary coil L22.

[0078] At time t2, the first driving IC 72 switches the first switching element 71 from the open state to the closed state. This applies a low DC voltage from the power supply 102 to one end Ep11 of the first primary coil L11. A first primary current flows through the first primary winding 811 that forms the first primary coil L11, generating a magnetomotive force in the first primary coil L11. Furthermore, an electromagnetic flux φa2 is generated in the first through core 61, traveling from the other end 612 to the one end 611, and a magnetic field corresponding to the electromagnetic flux φa2 acts on the core 60. The direction of the electromagnetic flux φa2 is the same as the blocking magnetic flux φs2. This amplifies the magnetic flux generated in the closed magnetic path of the core 60. As a result, the current and ignition energy supplied to the spark plug 101 can be further increased.

[0079] As described above, the first driving IC 72 alternately turns on and off the first primary coil L11 multiple times. The second driving IC 74 turns on the second primary coil L21 at the same time that the first driving IC 72 turns off the first primary coil L11, and then turns off the second primary coil L21 at the same time that the first driving IC 72 turns on the first primary coil L11. By performing this type of control, the flame generated around the spark plug 101 can be maintained for a longer period of time.

[0080] 2. Second Embodiment Next, a second embodiment of the present invention will be described. The following description will focus on differences from the first embodiment, and redundant description of parts equivalent to those in the first embodiment will be omitted. Furthermore, members having structures equivalent to those in the first embodiment will be described using the same reference numerals as in the first embodiment.

[0081] Fig. 9 is a perspective view of the ignition coil 104 according to this embodiment. As shown in Fig. 9, the ignition coil 104 has a first coil set 40, a second coil set 50, and an iron core 60B.

[0082] The core 60B of this embodiment has a structure in which a first through core 61, a second through core 62, a one-end outer periphery core 63, an other-end outer periphery core 64, and a center core 65B are combined together. The first through core 61, the second through core 62, the one-end outer periphery core 63, the other-end outer periphery core 64, and the center core 65B are each formed of, for example, laminated steel plates in which silicon steel plates are stacked. However, steel plates other than silicon steel plates may also be used for the first through core 61, the second through core 62, the one-end outer periphery core 63, the other-end outer periphery core 64, and the center core 65B. Furthermore, each of the first through core 61, the second through core 62, the one end side outer circumferential core 63, the other end side outer circumferential core 64, and the center core 65B may be a powder core formed from a sintered material.

[0083] As in the first embodiment, the one-end outer circumferential core 63 is placed above one end of the first penetrating core 61 in the first axial direction and above one end of the second penetrating core 62 in the second axial direction. The other-end outer circumferential core 64 is placed above the other end of the first penetrating core 61 in the first axial direction and above the other end of the second penetrating core 62 in the second axial direction. In this way, the one-end outer circumferential core 63 and the other-end outer circumferential core 64 each connect the first penetrating core 61 and the second penetrating core 62.

[0084] The center core 65B extends substantially horizontally and in a columnar shape substantially parallel to the first axial direction and the second axial direction. When the ignition coil 104 is viewed from above, the center core 65B is located between the first penetrating core 61 and the second penetrating core 62. One end 651B of the center core 65B is connected to the one-end-side outer periphery core 63. The other end 652B of the center core 65B is connected to the other-end-side outer periphery core 64. In other words, the center core 65B is located between the first penetrating core 61 and the second penetrating core 62, and connects the one-end-side outer periphery core 63 and the other-end-side outer periphery core 64.

[0085] This forms a single annular closed magnetic circuit connecting the first through core 61, a portion of the one-end outer periphery core 63, the center core 65B, and a portion of the other-end outer periphery core 64 in this order. Also, a single annular closed magnetic circuit is formed connecting the second through core 62, a portion of the one-end outer periphery core 63, the center core 65B, and a portion of the other-end outer periphery core 64 in this order. In this embodiment, when a DC voltage from the power supply 102 is applied to the first primary coil L11, an electromagnetic flux is generated that travels through the first through core 61, a portion of the one-end outer periphery core 63, the center core 65B, and a portion of the other-end outer periphery core 64 in this order. In addition, in this embodiment, when a DC voltage from the power supply 102 is applied to the second primary coil L21, an electromagnetic flux is generated that travels in the order of the second through core 62, a portion of the other end side outer core 64, the center core 65B, and a portion of the one end side outer core 63.

[0086] In this embodiment, the upper end of the one-end outer periphery core 63, the upper end of the other-end outer periphery core 64, and the upper end of the center core 65B are positioned higher than the first secondary coil L12 and the second secondary coil L22, respectively. That is, the upper end of the one-end outer periphery core 63, the upper end of the other-end outer periphery core 64, and the upper end of the center core 65B are positioned higher and closer to the resin surface 109 and the opening 120 of the case 107, respectively. This allows heat generated from the primary coils L11, L21, etc. of each coil set 40, 50 to be transferred upward via the upper end of the one-end outer periphery core 63, the upper end of the other-end outer periphery core 64, and the center core 65B, and dissipated above the case 107, while suppressing the influence of the thermal resistance of the molded resin that constitutes the resin portion 108.

[0087] FIG. 10 is a perspective view of an ignition coil 104 according to a third modified example. FIG. 11 is a perspective view of the ignition coil 104 of FIG. 10 with the resin cover 66 removed from the one-end outer core 63, the other-end outer core 64, and the center core 65B. As shown in the third modified example in FIGS. 10 and 11 , the one-end outer core 63 may be disposed adjacent to one end face of the first penetrating core 61 in the first axial direction and adjacent to one end face of the second penetrating core 62 in the second axial direction. The other-end outer core 64 may be disposed adjacent to the other end face of the first penetrating core 61 in the first axial direction and adjacent to the other end face of the second penetrating core 62 in the second axial direction. Even in this case, the one-end outer core 63 and the other-end outer core 64 can connect the first penetrating core 61 and the second penetrating core 62, respectively.

[0088] In this modification, the center core 65B, a portion of the one-end outer periphery core 63, and a portion of the other-end outer periphery core 64 are all formed from a single member. This reduces the number of parts in the entire ignition coil 104, including the core 60B. However, as shown in a fourth modification in FIG. 12 , the center core 65B, the one-end outer periphery core 63, and the other-end outer periphery core 64 may be formed from separate members. Furthermore, the center core 65B and one of the portion of the one-end outer periphery core 63 and the portion of the other-end outer periphery core 64 may be formed from separate members. This allows even a complex-shaped core 60B to be manufactured by punching material with a good yield when manufacturing the steel plate from which the core 60B is formed, making it easier to form the core 60B.

[0089] That is, as shown in a third modified example in FIG. 11 , the center core 65B and at least a portion of the one-end outer circumferential core 63 and / or at least a portion of the other-end outer circumferential core 64 may be formed from a single member. This reduces the number of parts in the entire ignition coil 104 including the core 60B. Also, as shown in a fourth modified example in FIG. 12 , the center core 65B and at least a portion of the one-end outer circumferential core 63 and / or at least a portion of the other-end outer circumferential core 64 may be formed from separate members. This allows the center core 65B and the one-end outer circumferential core 63 and / or the other-end outer circumferential core 64 to be manufactured by punching material with good yield when manufacturing the steel plates used to form these components, making it easier to form the core 60B.

[0090] When the ignition device 1 is operated, the first driving IC 72 alternately turns on and off the first primary coil L11 multiple times. When the first primary coil L11 is de-energized, a blocking magnetic flux is generated that travels through the first through core 61, a portion of the other-end outer circumferential core 64, the center core 65B, and a portion of the one-end outer circumferential core 63 in this order. At this time, the voltage applied to one end Eg12 of the first secondary coil L12 ranges from minus several thousand volts to several tens of thousands volts relative to the ground point 152. This generates an electric spark in the spark plug 101 connected to one end Eg12 of the first secondary coil L12, igniting the fuel, and an induced current (first secondary current) flows through the first secondary coil L12.

[0091] Furthermore, the second driving IC 74 alternately turns on and off the second primary coil L21 multiple times. When the second primary coil L21 is de-energized, a blocking magnetic flux is generated that travels through the second through core 62, a portion of the other-end outer circumferential core 64, the center core 65B, and a portion of the one-end outer circumferential core 63 in this order. At this time, the voltage value applied to one end Eg22 of the second secondary coil L22 ranges from minus several thousand volts to several tens of thousands volts relative to the ground point 152. As a result, the electric spark and flame generated around the spark plug 101 connected to one end Eg22 of the second secondary coil L22 can be maintained, and an induced current (second secondary current) flows through the second secondary coil L22.

[0092] <3. Modifications> Although exemplary embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0093] The ignition coil and ignition device of the present invention may be installed not only in vehicles such as automobiles, but also in various devices such as generators and industrial machinery, and may be used to generate an electric spark in the spark plug of an internal combustion engine to ignite fuel.

[0094] The detailed shapes and structures of the above-described ignition coil and ignition device may be appropriately modified without departing from the spirit of the present invention. Furthermore, the elements appearing in the above-described embodiments and modifications may be appropriately combined without causing any contradiction. [Explanation of symbols]

[0095] 1 Ignition device 60,60B iron core 61 First through core 62 Second through core 63 One end outer core 64 Other end outer core 65B central core 71 first switching element 72 First driving IC (first control unit) 73 Second switching element 74 Second driving IC (second control unit) 101 Spark plug 102 Power supply 104 Ignition coil 105 First Igniter 106 Second Igniter 107 cases 108 Resin part 109 Resin Surface 120 opening 611 (First iron core) one end 612 (the other end of the first iron core) 621 (One end of the second iron core) 622 (the other end of the second iron core) 651B (Central Core) One End 652B (other end of center core) 811 First primary winding 812 1st secondary winding 821 Second Primary Winding 822 Secondary Winding 910 (case) internal space Eg11 (the other end of the first primary coil) Eg12 (One end of the first secondary coil) Eg21 (other end of second primary coil) Eg22 (one end of the second secondary coil) Ep11 (one end of the first primary coil) Ep12 (other end of first secondary coil) Ep21 (one end of the second primary coil) Ep22 (other end of second secondary coil) HG high voltage terminal L11 First primary coil L12 First secondary coil L21 Second primary coil L22 Secondary coil

Claims

1. An ignition coil for an internal combustion engine, a first primary coil having a first primary winding, one end of which is applied with a DC voltage and the other end of which is connected to a ground; a first secondary coil comprising a first secondary winding; a first through core that passes through an inside of the first primary coil and an inside of the first secondary coil and electromagnetically couples the first primary coil and the first secondary coil; a second primary coil having a second primary winding, one end of which is applied with the DC voltage and the other end of which is connected to a ground; a second secondary coil comprising a second secondary winding; a second through core that passes through an inside of the second primary coil and an inside of the second secondary coil and electromagnetically couples the second primary coil and the second secondary coil; a one-end-side outer peripheral core that connects one end of the first through core and one end of the second through core; an other-end-side outer peripheral core that connects the other end of the first penetrating core and the other end of the second penetrating core; a case having a concave shape with an opening formed at the upper end by opening upward, the case accommodating the first primary coil, the first secondary coil, the first through core, the second primary coil, the second secondary coil, the second through core, the one end side outer peripheral core, and the other end side outer peripheral core; and The case is filled with a thermosetting molding resin, an upper end portion of the one end side outer peripheral iron core and an upper end portion of the other end side outer peripheral iron core are positioned higher than the first secondary coil and the second secondary coil, respectively;

2. 2. The ignition coil according to claim 1, An ignition coil, wherein an upper end portion of the one end side outer peripheral iron core and / or an upper end portion of the other end side outer peripheral iron core are exposed above an upper surface of the molding resin.

3. 2. The ignition coil according to claim 1, a center core that is disposed between the first through core and the second through core and connects the one end side outer peripheral core and the other end side outer peripheral core; an ignition coil further comprising:

4. 4. The ignition coil according to claim 3, An ignition coil, wherein the center core and at least a portion of the one end side outer peripheral core and / or at least a portion of the other end side outer peripheral core are each formed from a single member.

5. 4. The ignition coil according to claim 3, The ignition coil, wherein the center core and at least a portion of the one end side outer peripheral core and / or at least a portion of the other end side outer peripheral core are formed from separate members.

6. An ignition coil according to any one of claims 1 to 5; a power supply device that applies the DC voltage to one end of the first primary coil and one end of the second primary coil; a first switching element that is interposed between the other end of the first primary coil and a ground point and that is capable of switching between energization and interruption of a first primary current that flows from the power supply device to the first primary coil; a second switching element that is interposed between the other end of the second primary coil and a ground point and that is capable of switching between energization and interruption of a second primary current that flows from the power supply device to the second primary coil; a first control unit that controls switching of the first switching element; a second control unit that controls switching of the second switching element; an ignition plug that ignites fuel by discharging in a gap based on a high voltage induced at one end of the first secondary coil and / or a high voltage induced at one end of the second secondary coil; An ignition device having:

7. 7. The ignition device according to claim 6, a high-voltage terminal held by the case below the ignition coil and interposed in conductors connecting one end of the first secondary coil and one end of the second secondary coil to the spark plug; The ignition device further comprises:

Images