JP2007081085A - Ignition coil for internal combustion engines - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small ignition coil for internal combustion engines excellent in engine layout property attaining miniaturization. <P>SOLUTION: The small ignition coil for internal combustion engines accommodates a primary bobbin 4 winding and housing a primary coil 2, a secondary bobbin 5 winding and housing a secondary coil 3, and a core 7 constituting a magnetic circuit composed of a center core 7c and side cores 7a, 7b in a coil case 9 whose one side is opened. Insulating resin is charged and integrated in the coil case 9. It is composed by covering the side cores 7a, 7b of the core 7 constituting the magnetic circuit with an elastic member 6, and by covering the center core 7c connected to the side core 7a, 7b with a resin composing the primary bobbin 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine ignition coil that is mounted for each ignition plug of an internal combustion engine.

  In general, an ignition coil for an internal combustion engine is directly attached to a cylinder head or fixed to an engine or a body with a bracket or the like. Recently, the ignition coil is disposed on an ignition plug of each cylinder and directly fixed to a cylinder head cover. Has become the mainstream. Therefore, in recent years, in order to improve the degree of freedom in designing the layout of various engine parts, there is an increasing demand for downsizing the ignition coil for an internal combustion engine.

Therefore, conventionally, as an ignition device for an internal combustion engine that generates a high voltage in a secondary coil according to a primary current flowing in a primary coil of an ignition coil and sends the high voltage to an external spark plug, the size of the device is increased. In addition, an ignition device for an internal combustion engine that prevents the occurrence of dielectric breakdown of the insulating resin has been proposed (see, for example, Patent Document 1).
JP-A-8-306558 (FIG. 4 on the second page)

  However, in the ignition coil device for an internal combustion engine described in Patent Document 1, as is apparent from FIG. 4, the iron core constituting the magnetic circuit is exposed to the outside after being subjected to rust prevention treatment such as painting. Was. Moreover, in the ignition coil device for an internal combustion engine described in Patent Document 1, the side wall of the storage case 4 also serves as the bottom of the square tubular iron core holding portion 4c provided on the outer wall of the storage case 4. It has become.

  For this reason, in the ignition coil device for an internal combustion engine described in Patent Document 1, such a configuration has been an impediment to downsizing.

  An object of the present invention is to provide a small ignition coil for an internal combustion engine that is miniaturized and excellent in engine layout.

  An ignition coil for an internal combustion engine according to the present invention comprises a primary bobbin that winds and stores a primary coil, a secondary bobbin that winds and stores a secondary coil, a center core, and a side core to form a magnetic circuit. In an internal combustion engine ignition coil in which a core is housed in an open coil case and an insulating resin is enclosed in the coil case and integrated, the side core of the core constituting the magnetic circuit is an elastic member And the center core connected to the side core is covered with a resin constituting the primary bobbin.

  ADVANTAGE OF THE INVENTION According to this invention, the ignition coil for internal combustion engines which was small and excellent in reliability is realizable.

  First, in this invention, the core which comprises a magnetic circuit is accommodated in the coil case together with the primary coil and the secondary coil. However, in the state where the core (iron core) is exposed as it is, excessive heat is generated at the edge portion of the core due to the difference in the coefficient of linear expansion between the insulating resin that performs electrical insulation between the primary coil and the secondary coil. Stress acts and cracks occur in the insulating resin. Therefore, it is necessary to cover the core with an elastic member or resin and relieve the thermal stress. However, after the core is covered with the elastic member, the coil portion wound around the primary bobbin and the secondary bobbin is assembled. The entire coil becomes large. Therefore, the present invention is achieved by combining a bobbin formed of an elastic member and a resin member so as to cover the iron core.

  That is, the present invention provides a primary bobbin for winding and storing a primary coil, a secondary bobbin for winding and storing a secondary coil, and a core that constitutes a magnetic circuit including a center core and a side core. An ignition coil for an internal combustion engine, which is housed in an open coil case and encapsulates and integrates an insulating resin, and covers the side core of the core constituting the magnetic circuit with an elastic member. This is achieved by covering the connected center cores with the resin constituting the primary bobbin.

  FIG. 1 is a sectional view of an internal combustion engine ignition coil according to an embodiment of the present invention.

  In FIG. 1, the ignition coil 1 includes a core 7 constituting a magnetic circuit. The core 7 includes a side core formed in a rectangular ring shape, and a center core 7c that is connected to one end of the side core and extends to the inner center of the rectangular ring of the side core. This side core is divided into two, and is constituted by a first side core and a second side core. The side cores 7a and 7b and the center core 7c are formed by laminating dozens of electromagnetic steel plates having a thickness of about 0.2 to 0.5, and the side cores 7a and 7b and the center core 7c form a magnetic circuit. It is configured.

  The center core 7c is accommodated inside the primary bobbin 4 in which the primary coil 2 is wound and accommodated. A secondary bobbin 5 is arranged around the primary coil 2 wound around the primary bobbin 4 with a distance from the primary coil 2 wound around the primary bobbin 4. A secondary coil 3 is wound around the secondary bobbin 5.

  A primary coil 2 wound around the primary bobbin 4 and a secondary coil 3 wound around the secondary bobbin 5 are accommodated in a coil case 9. A thermosetting resin such as an epoxy resin 8 is enclosed in the coil case 9. That is, the primary coil 2, the secondary coil 3, the primary bobbin 4, and the secondary bobbin 5 are insulated and fixed in the coil case 9 by the thermosetting resin (for example, epoxy resin) 8 in the coil case 9. Is contained.

  Further, the igniter 10 that controls the function of cutting off the energization of the primary coil 2 and the secondary coil 3 is arranged in a different igniter accommodating portion 9 a different from the coil portion that accommodates the primary coil 2 and the secondary coil 3. It has become. The electrical connection between the igniter 10 disposed in the igniter accommodating portion 9a and the coil portion accommodating the primary coil 2 and the secondary coil 3 is performed by connecting the primary terminal 11 attached to the primary bobbin 4 and the igniter terminal 10a. By doing that. Further, the external connection such as transmission / reception of signals in the igniter 10 and the supply of power to the igniter 10 is performed by connecting the igniter 10 disposed in the igniter accommodating portion 9 a to the outside in a part of the coil case 9. This is done by connecting the connector terminal 12 of the connector portion 9b and an external terminal (not shown).

  As described above, when the coil case 9 includes not only the winding portions of the primary coil 2 and the secondary coil 3 but also the core portions including the side cores 7a and 7b and the center core 7c, the side core 7a, In the core 7 part constituted by 7b and the center core 7c, there is a difference in the respective linear expansion coefficients. Therefore, the core 7 part constituted by the side cores 7a and 7b and the center core 7c and the insulating epoxy resin 8 Stress concentrates on the interface, particularly each core edge portion 7d.

  Therefore, a thermal stress relaxation layer is required at the interface between the core 7 portion constituted by the side cores 7a and 7b and the center core 7c and the insulating epoxy resin 8, particularly at each core edge portion 7d where stress is concentrated. In this embodiment, the side core 7 a and the side core 7 b are covered with an elastic member 6 such as rubber, and the center core 7 c is accommodated inside the primary bobbin 4 to reduce thermal stress. As a material of the elastic member 6 for molding the side core 7a, the side core 7b, and the center core 7c, heat-resistant silicone rubber or the like is suitable. However, stress relaxation is possible even with a resin or the like.

  FIG. 2 shows an enlarged view of the main configuration of the ignition coil for the internal combustion engine shown in FIG.

  In FIG. 2, most of the periphery of one side core 7 a of the core 7 is covered with the elastic member 6. The other side core 7 b of the core 7 is covered with the elastic member 6, and a part of the periphery is covered not by the elastic member 6 but by a part of the primary bobbin 4. That is, one end portion of the primary bobbin 4 is formed in a claw shape with a flange-shaped tip projecting outward, and a core positioning portion 4a that engages with the other side core 7b is formed. The fitting portion of the core positioning portion 4a of the other side core 7b covered by the core positioning portion 4a of the primary bobbin 4 is not covered with the elastic member 6, and the side core 7b is exposed. Therefore, the core positioning part 4a is used to position the primary bobbin 4 and the side core 7b by fitting the core positioning part 4a of the side core 7b to the exposed part of the side core 7b that is not covered with the elastic member 6, and Instead of stress relaxation by the elastic member 6, stress relaxation is performed by the side core 7b.

  In general, a fixing portion of the primary bobbin 4 is provided on the elastic member 6. For this reason, the ignition coil for an internal combustion engine is easy to increase in size in the height direction, but in the case of the present embodiment, it contributes to downsizing by covering the other side core 7b of the core 7 with a part of the primary bobbin 4. can do. A pocket-shaped pocket portion 6 a for positioning the flange portion 4 b of the primary bobbin 4 is formed in the elastic member 6 that covers one side core 7 a of the core 7.

  FIG. 3 shows a plan view of the main configuration of the ignition coil for the internal combustion engine shown in FIG.

  In FIG. 3, the other side core 7 b of the core 7 is covered with the elastic member 6, but the periphery of the side core 7 b is not covered only with the elastic member 6. A part 7d of the side core 7b is covered with a part of the primary bobbin 4, and the side core 7b and the primary bobbin 4 are laterally covered by covering a part 7d of the side core 7b with a part of the primary bobbin 4. Is positioned against.

  On the other hand, one side core 7a of the core 7 is covered with the elastic member 6 in most of the periphery, but in order to position the side core 7a and the primary bobbin 4 in the lateral direction, the elasticity which covers the side core 7a. The member 6 is provided with a pocket portion 6a formed in a pocket shape. The pocket portion 6a provided in the elastic member 6 covering the side core 7a is adapted to be fitted with the flange portion 4b of the primary bobbin 4. As the material of the primary bobbin 4, a resin having good adhesiveness with the epoxy resin 8 such as a thermoplastic resin such as boribylene terephthalate (PBT) or modified polyphenylene ether (PPE) is used.

  Moreover, the convex part 13a is provided in the side surface of the side core 7a, and the convex part 13a is provided also in the side surface of the side core 7b, respectively. The convex portion 13 a can center the coil portion, which is a combination of the primary coil 2 and the secondary coil 3, with respect to the inner surface of the coil case 9 when the core 7 constituted by the side cores 7 a and 7 b is accommodated in the coil case 9. It is provided for positioning. Therefore, the elastic member 6 covered with the side cores 7a and 7b is centered by the convex portion 13a formed on the side surface of the side core 7a so as to correspond to the convex portion 13a of the side core 7a and the convex portion 13a of the side core 7b. A protrusion 6b is formed.

  The side core 7a, the side core 7b, and the center core 7c used in the present embodiment are usually made by laminating dozens of electromagnetic steel plates having a thickness of about 0.2 to 0.5, but have an arbitrary shape. A sintered electromagnetic material that can be formed into a single shape may be used.

  In this embodiment, the core 7 is divided into a center core 7c and side cores 7a and 7b, and the fitting portions of the side cores 7a and 7b have a structure as shown in FIG.

  In FIG. 4, a core exposed portion 7f where the side core 7a is exposed is formed in the fitting portion 7e where the elastic member mold 6c covered by the side core 7a and the elastic member mold 6d covered by the side core 7b are fitted. Has been. The core exposed portion 7f is a portion necessary for fixing the side core 7a with a mold when the side core 7a is covered with the elastic member mold 6c. By bringing the core exposed portion 7f to the fitting portion 7e, the core exposed portion 7f does not become an edge, thereby preventing thermal stress from concentrating.

  FIG. 5 is a cross-sectional configuration diagram showing another embodiment of the internal combustion engine ignition coil according to an embodiment of the present invention.

  In FIG. 5, most of the periphery of one side core 7 a of the core 7 is covered with the elastic member 6. The other side core 7 b of the core 7 is covered with the elastic member 6, and a part of the periphery is covered not by the elastic member 6 but by a part of the secondary bobbin 5. That is, one end portion of the secondary bobbin 5 is formed in a claw shape with a flange-shaped tip projecting outward, and a core positioning portion 5a that engages with the other side core 7b is formed. The fitting portion of the core positioning portion 5a of the other side core 7b covered by the core positioning portion 5a of the secondary bobbin 5 is not covered with the elastic member 6, and the side core 7b is exposed. . Therefore, by positioning the core positioning part 5a of the side core 7b in a position where the side core 7b not covered with the elastic member 6 is exposed, the core positioning part 5a positions the secondary bobbin 5 and the side core 7b. Instead of stress relaxation by the elastic member 6, stress relaxation is performed by the side core 7b.

  As described above, the primary bobbin 4 is disposed around the secondary coil 3 wound around the secondary bobbin 5 with a distance from the secondary coil 3 wound around the secondary bobbin 5. A primary coil 2 is wound around the primary bobbin 4. The secondary coil 3 wound around the secondary bobbin 5 and the primary coil 2 wound around the primary bobbin 4 are accommodated in the coil case 9.

  As described above, according to this embodiment, it is possible to provide a small ignition coil for an internal combustion engine having high thermal stress resistance.

It is a section lineblock diagram of an ignition coil for internal-combustion engines showing one example of the present invention. FIG. 2 is an enlarged view of a main configuration of an internal combustion engine ignition coil illustrated in FIG. 1. FIG. 3 is a plan view of a main configuration of an internal combustion engine ignition coil illustrated in FIG. 2. It is a figure which shows the fitting part of the two side cores of the ignition coil for internal combustion engines shown in FIG. FIG. 5 is an enlarged view of a main configuration showing another embodiment of an ignition coil for an internal combustion engine showing an embodiment of the present invention.

Explanation of symbols

1 ……………… Ignition coil 2 …………… Primary coil 3 ……………… Secondary coil 4 …………… Primary bobbin 4a ………… Core positioning part 4b ………… Head part 5… ………… Secondary bobbin 6 ……………… Elastic member 6a ………… Elastic member pocket 6b ………… Centering protrusion 6c ………… Elastic member mold 6d ………… Elastic member mold 7a …… …… Side core 7b ………… Side core 7c ………… Center core 7d ………… Primary bobbin positioning portion 7e ………… Core fitting portion 7f ………… Core exposed portion 8 …………… Insulating resin (epoxy) resin)
9 ......... Coil case 9a ............ Ignator housing 9b ………… Connector 10 ………… Ignator 10a ……… Ignator terminal 11 ………… Primary terminal 12 ………… Connector terminal 13a ……… Convex

Claims (5)

In a coil case in which a primary bobbin that winds and stores a primary coil, a secondary bobbin that winds and stores a secondary coil, and a core that is composed of a center core and a side core and constitutes a magnetic circuit is opened in one side An ignition coil for an internal combustion engine in which the insulating resin is enclosed and integrated in the coil case,
An ignition coil for an internal combustion engine, characterized in that a side core of a core constituting the magnetic circuit is covered with an elastic member, and the center core connected to the side core is covered with a resin constituting the primary bobbin. The ignition coil for an internal combustion engine according to claim 1,
An ignition coil for an internal combustion engine, wherein a corner portion of a core constituting the magnetic circuit is covered with either an elastic body or a resin constituting a primary bobbin. The ignition coil for an internal combustion engine according to claim 1 or 2,
The side core of the core constituting the magnetic circuit is divided into two parts, a first side core and a second side core, and the first side core and the second side core are fitted to each other. Comprising two side cores,
The elastic member of either the first side core or the second side core covered by the side core is formed by cutting out a part of the elastic member, and is made of a resin covering the center core. An internal combustion engine ignition coil provided with a pocket portion for fitting a flange-shaped core positioning portion formed at an end portion of a bobbin. The ignition coil for an internal combustion engine according to claim 3,
An exposed portion that is not covered with the elastic member is provided on either the first side core or the second side core of the fitting portion to which the first side core and the second side core are fitted. Ignition coil for internal combustion engines. The ignition coil for an internal combustion engine according to claim 3 or 4,
The elastic member covered by the first side core or the second side core includes the center core and the first and second side cores on the outer peripheral surface thereof, and the core constituting the magnetic circuit is accommodated in the coil case. An internal combustion engine ignition coil provided with a positioning centering protrusion for centering with respect to the inner surface of the coil case.

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