JP2014022602A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil in which the mold resin is less likely to be cracked even if the ignition coil is made compact.SOLUTION: An outer peripheral core 40 abutting against a center 30 and forming a closed magnetic circuit is configured to have a core central part 40a located above a secondary coil L2, and a first protrusion 40b projecting downward from the tip of the core central part 40a and facing an ignitor TR. The surface of the first protrusion 40b facing the ignitor TR is coated with an elastic body ER in a contact state, and a cover 3 large enough to conceal the ignitor and the outer peripheral core, in the plan view, is located above the ignitor TR and the outer peripheral core 40.

Description

  The present invention relates to an ignition coil that realizes an ignition discharge of an internal combustion engine such as an automobile engine, and more particularly to an ignition coil that is devised so that cracks do not occur in a filled resin even when the size is reduced.

  An ignition coil that is indispensable for the operation of an internal combustion engine is generally composed of a primary coil and a secondary coil, and a magnetic core that forms an open magnetic path or a closed magnetic path of magnetic flux linked to them. As the magnetic core, an electromagnetic steel plate that is an integrated stack of thin plates such as silicon steel plates is used, and the primary coil, secondary coil, and magnetic core are filled with a thermosetting resin in a coil case. By doing so, the electrical insulation of each part is ensured.

JP 2001-23839 A JP 2005-183515 A JP 2008-198833 A

  By the way, since the ignition coil is subjected to thermal stress due to engine operation and suspension, the mold resin cracks based on the difference in thermal expansion coefficient of each member accommodated in the coil case, and the insulation performance deteriorates over time. May disturb the stable operation.

  For this reason, an appropriate measure is desired, but simply increasing the number of insulating members or securing the insulating distance cannot meet the demand for downsizing and cost reduction of the device.

  For example, in the ignition coil of Patent Document 1, the magnetic core is composed of an I-type center core and an O-type outer core that circulates the entire secondary coil, and the size of the ignition coil is increased by the O shape. To do. Further, in this ignition coil, the outer peripheral core is developed on a horizontal plane, so that an occupied space on the horizontal plane is required, and the mounting position on the engine block is restricted.

  In addition, the invention of Patent Document 1 adopts a configuration in which a partition wall is provided between the igniter and the magnetic core. In this sense, the purpose of downsizing and cost reduction of the apparatus is hindered.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an ignition coil in which an appropriate measure is taken that is difficult to cause cracks in the mold resin even when the size is reduced.

  To achieve the above object, the present invention provides a primary coil in which a primary winding is wound around a primary bobbin, a secondary coil in which a secondary winding is wound around a secondary bobbin in which the primary coil is inserted, and a primary coil A central core to be inserted into the bobbin, an outer peripheral core that is in contact with the central core in a state including a part of the secondary coil to form a closed magnetic circuit, and disposed adjacent to the outer side of the outer peripheral core to energize the primary coil. An internal combustion engine having an igniter to be controlled and a current-carrying unit that supplies an output voltage of a secondary coil to a spark plug, and configured such that each member is accommodated in a coil case filled with a thermosetting resin. The outer peripheral core is an ignition coil having a core central portion disposed above the secondary coil, and a first projecting portion that projects downward from one end of the core central portion and faces the igniter. First protrusion configured and facing the igniter Surface is covered by an elastic body contact, the upper portion of the igniter and the outer core, a cover member sized to conceal igniter and the outer core in a plan view are arranged.

  In the present invention, terms such as upward, downward, vertical direction, forward, backward, front-rear direction, etc. may be used, but the vertical direction and front-rear direction are merely meanings such as the first direction and the second direction, Of course, it does not necessarily mean a vertical direction or a horizontal direction in the ignition coil in use.

  In any case, in the present invention, the surface of the first projecting portion facing the igniter is covered with a contact elastic body, and the igniter and the outer core are concealed in plan view on the igniter and the outer core. Since the cover body is arranged, cracks in the thermosetting resin can be effectively suppressed.

  That is, in the present invention, since the surface of the first projecting portion facing the igniter is covered with the elastic body in a contact state, it is possible to effectively buffer the thermal stress and without providing a partition wall or the like. The occurrence of cracks toward the igniter can be suppressed. For example, in a magnetic steel sheet in which a large number of thin plates are integrated by bonding or caulking, microscopically, there are right-angled corners for each thin plate, and all the corners are likely to become the base points of cracks. Since the corners of the laminated thin plates are covered with the elastic body in contact, the base point of the crack is eliminated.

  Moreover, in this invention, the outer periphery core is expand | deployed to the up-down direction, The occupied space in a horizontal surface can be suppressed by that much, and the freedom degree of an attachment position is high. In addition, since the cover body is sized to cover the igniter and the outer core in plan view, the corners of the thin electromagnetic steel sheet are exposed to the thermosetting resin. Even if it is made to do, the growth of the crack which goes to a coil top surface from an outer periphery core can be blocked | prevented.

  The cover body is preferably configured by integrating a box-shaped main body portion covering the uppermost portion of the outer peripheral core and a bent plate-shaped appendage portion covering the uppermost portion of the igniter. In this case, it is effective that the uppermost surface of the main body portion of the cover body and the attachment portion of the cover body form substantially the same plane. The cover body is typically made of polybutylene terephthalate (PBT), and the main body portion is formed in a substantially rectangular shape in plan view.

  The outer peripheral core is configured to have a second projecting portion projecting downward from the other end portion of the core central portion, and a thin plate integrally forming the core central portion, the first projecting portion, and the second projecting portion. Typically, an outer core is formed by laminating a large number of U-shaped electrical steel sheets.

  The core central portion of the outer core is partially covered with an elastic body that is in contact, while the uppermost surface of the elastic body and the uppermost surface of the outer core form substantially the same plane to receive the cover body. It is effective in suppressing the vertical dimension. In any case, it is preferable that the elastic body has a thickness of 0.5 to 1.0 mm, and the elastic body has a hardness at a temperature of 150 ° C. as evaluated by Shore D. It is suitable that it is 35D-50D.

  According to the above-described present invention, it is possible to realize an ignition coil in which the filling resin is hardly cracked even if the size is reduced.

It is the schematic of the completion state about the ignition coil which concerns on an Example. It is the schematic plan view (a) of the ignition coil of FIG. 1, and AA sectional drawing (b). It is a circuit diagram of the ignition coil of FIG. It is a perspective view which shows a primary bobbin and a center core. It is drawing which shows an outer periphery core. It is drawing which shows a resin cover.

  Hereinafter, the present invention will be described in more detail based on examples. FIG. 1 is a perspective view (a) of an ignition coil CL according to an embodiment and six views (b) to (g) of the ignition coil CL. FIG. 2 includes a plan view and a partial cross-sectional view (a) of the ignition coil CL, and a cross-sectional view taken along the line AA. FIG. 3 is a circuit diagram showing an electric circuit constituting the ignition coil CL. In the following description, for the sake of convenience, the upper and lower sides may be referred to as “upper” and “lower”, and the left and right sides of the paper may be referred to as “rear” and “front”.

  The ignition coil CL according to the present embodiment integrates and integrates a connector case 2 containing a connection terminal with an external device (ECU) into the coil case 1 as well as a primary coil L1, a secondary coil L2, a diode D, and an igniter. The coil case 1 containing TR or the like is completed by filling a thermosetting mold resin. The coil case 1 and the connector case 2 are made of a resin such as PBT (polybutylene terephthalate), and both are integrated by being partly fitted in the fitting groove 4 shown in FIG. Has been.

  Specifically, the coil case 1 is configured to include a main body portion BDY, a mounting flange FG, and an insertion portion IN, and a protector (not shown) that is externally fitted to the insertion portion IN is inserted into the plug hole. Thus, the ignition coil CL of the embodiment is used. The protector (not shown) incorporates a conductive spring, and the output voltage of the secondary coil L2 is supplied to the spark plug PG in the plug hole through the conductive spring.

  As shown in the perspective view of FIG. 1A, the mold resin filled in the coil case 1 does not reach the peripheral edge ED of the main body BDY, and the filling amount is set to a height at which the resin cover 3 is exposed. ing. As shown in FIG. 2B, the resin cover 3 (3a + 3b) completely covers the upper surface of the outer peripheral core 40 and the igniter TR, and the insulation performance is improved by this configuration, so the filling amount of the mold resin is suppressed. And cost reduction can be realized. In addition, you may reduce the height dimension of a coil case corresponding to the upper surface of mold resin.

  As shown in FIG. 2, the ignition coil CL of the embodiment includes a primary coil L1 in which a primary winding 11 is wound around a primary bobbin 10, and a secondary coil L2 in which a secondary winding 21 is wound around a secondary bobbin 20. The diode D disposed on the secondary bobbin 20, the central core 30 inserted into the primary bobbin 10, the outer peripheral core 40 in contact with the two end faces of the central core 30, the outer core 40 and the central core 30 Permanent magnet 50 disposed on the abutting surface, igniter TR for controlling energization of primary coil L1, high voltage terminal 60 for supplying the output voltage of secondary coil L2 to spark plug PG, outer core 40 and igniter TR It has a resin cover 3 and the like that cover the upper surface of the cover.

  As shown in FIG. 2B, the igniter TR is arranged with its connection terminal facing upward. Then, a necessary amount of mold resin is filled in order to fill the gaps between the respective parts. FIG. 2 shows a state before the filling.

  The central core 30 and the outer core 40 together with the permanent magnet 50 form a closed magnetic circuit that links the primary winding 11 of the primary coil L1 and the secondary winding 21 of the secondary coil L2. The permanent magnet 50 forms a magnetic field opposite to the magnetic field formed when the primary coil L1 is conducted. Each of the central core 30 and the outer core 40 is made of an electromagnetic steel plate such as silicon steel, and is formed by laminating a plurality of thin plates in the direction perpendicular to the paper surface of FIG. It is integrated by.

  The primary coil L1, the secondary coil L2, the igniter TR, and the diode D constitute the ignition circuit shown in FIG. 3 as a whole, and control for supplying an ignition pulse received from an ECU (Engine Control Unit) to the igniter TR. A terminal T1, a power supply terminal T2 for supplying a battery voltage to the primary coil L1, and a ground terminal T3 are arranged inside the connector case 2. The igniter TR is composed of, for example, an IGBT (Insulated Gate Bipolar Transistor), and the diode D is arranged in a direction that prevents only positive discharge toward the ground and realizes only negative discharge.

<Central core 30>
FIG. 4 is a perspective view showing the primary bobbin 10 and the central core 30. As shown in the figure, the central core 30 includes a core body part 31, a front end contact part 32 continuous in the front direction of the core body part 31, a proximal end contact part 33 continuous in the rear direction of the core body part 31, It is divided into.

  As illustrated, the center core 30 has a top surface 31a, a bottom surface 31b, and two outer surfaces 31c, and is formed in a substantially rectangular parallelepiped shape. Here, a staircase portion is formed from the uppermost surface 31a of the central core 30 toward the outer surface 31c, and a similar staircase portion is also formed from the bottom surface 31b of the central core 30 toward the outer surface 31c.

  Therefore, the outer surface of the primary bobbin 10 that holds the central core 30 can be formed into a substantially arc shape with a rounded corner, and even if the primary winding 11 is strongly wound around the primary bobbin 10 at a high speed, the primary bobbin 10 may be Troubles such as cutting will not occur.

  As shown in FIG. 2B, the distal end contact portion 32 of the central core 30 is in contact with the outer peripheral core 40 via the permanent magnet 50, and the proximal end contact portion 33 of the central core 30 is directly connected to the outer peripheral core. 40.

  As shown in FIG. 4, the tip contact portion 32 includes a core bottom surface BS formed at a position below the bottom surface 31 b of the core body portion 31, a flat front surface 34 that is inclined upward from the core bottom surface BS and extends upward, An upper back surface 35 extending downward from the top of the direction 34 and continuing to the uppermost surface 31 a of the core body 31, a lower back surface 36 extending upward from the core bottom surface BS and continuing to the bottom surface 31 b of the core body 31, and an extension surface 37 and a pair of side end surfaces 38 and 38 that connect the front surface 34 to the upper and lower back surfaces 35 and 36.

  As illustrated, the core bottom surface BS is formed with a cut groove GV that goes straight in the width direction of the core body 31. Then, the end of the conductor plate PT1 connected to the ground terminal T3 of the connector case 2 is inserted at the center position in the length direction of the cut groove GV (see FIG. 2B). Therefore, the central core 30 is constantly maintained at the ground potential.

  In the tip contact portion 32, the upper communication surface FA1 that connects the front surface 34 and the upper back surface 35 is formed as an arc surface having a predetermined curvature. For this reason, among the many laminated steel plates constituting the central core 30, the right-angled corners of the peripheral edge constituting the upper connecting surface FA1 disappear, and it is difficult to become the base point of the mold resin crack.

  The base end abutting portion 33 includes a bottom surface 33b and a side surface 33c continuous with the bottom surface 31b and the side surface 31c of the core body portion 31, a top surface 33a formed at a position lower than the top surface 31a of the core body portion 31, and the core body portion. 31 and an inclined surface 39 that connects the upper surfaces 31a and 33a of the base end contact portion 33 in a V shape, and rear surfaces 33d that are substantially orthogonal to the upper surface 33a, the bottom surface 33b, and the side surface 33c, respectively. It is configured.

  As shown in FIG. 2B, the upper surface 33a and the inclined surface 39 of the proximal end contact portion 33 are in contact with the end surface of the outer peripheral core 40 having a bent shape corresponding thereto. In this embodiment, since the outer core 40 and the center core 30 are in contact with each other through the inclined surface 39 cut into a V shape, a contact area can be ensured, leakage flux is reduced, and a predetermined magnetic resistance is obtained. Can be maintained.

  As shown in FIG. 2B, the conductor plate PT <b> 2 formed by folding is disposed on the bottom surface 33 b of the base end contact portion 33, and the bottom surface 33 b of the base end contact portion 33 and the rear surface of the outer core 40. In addition, each has a bullet contact. Therefore, the potential of the outer peripheral core 40 can be reliably maintained at the same ground potential as that of the central core 30.

<Primary bobbin 10>
As shown in FIG. 4, the primary bobbin 10 includes a body portion 12 that holds the core body portion 31 of the central core 30, a distal end portion 13 that holds the distal end contact portion 32 of the central core 30, and a proximal end of the central core 30. It is divided into a base end portion 14 that holds the contact portion 33. The central core 30 is inserted into the primary bobbin 10 in the direction of the arrow in FIG. 4. When the central core 30 is completely inserted, the rear surface of the primary bobbin coincides with the rear surface 33 d of the central core 30. The primary bobbin 10 and the rear surface of the central core 30 are in contact with the inner surface of the coil case 1 (see FIG. 2B).

  The body portion 12 of the primary bobbin 10 is set to have substantially the same height as the side surface 31c of the core main body portion 31 in order to suppress the height of the primary coil L1 to the minimum necessary, and the top surface and the bottom surface do not exist. It has become. Therefore, the lowermost part of the body part 12 is continuous with the bottom surface 31 b of the core body part 31, and the uppermost part of the body part 12 is continuous with the uppermost surface 31 a of the core body part 31.

  Further, the side surface 15 of the primary bobbin body portion 12 has a substantially arc shape with a rounded outer contour. As described above, since the side surface 31c of the core body 31 is formed in a stepped shape, the outer surface and the inner surface of the primary bobbin body 12 are correspondingly rounded to set the side surfaces 15c. The wall thickness is substantially uniform.

  And the primary coil L1 is comprised by winding the primary winding 11 in the primary bobbin trunk | drum 12 of such a structure. The primary winding 11 is wound directly around the exposed core body 31 or the primary winding 11 is wound with an appropriate insulating sheet interposed.

  The front end portion 13 of the primary bobbin 10 has a holding bottom surface 13 a that holds the core bottom surface BS, the lower back surface 36, and the extension surface 37 and a pair of side end surfaces 38, 38 with respect to the front end contact portion 32 of the central core 30. It has holding side surfaces 13b and 13b to hold, and a holding back surface 13c that comes into contact with the upper back surface 35.

  A flange portion PR protruding forward is formed at the upper end portion of the holding back surface 13c. In addition, a raised portion RI that forms a mold resin filling passage is formed in the upper portion of the holding back surface 13c. Here, the flange portion PR is arranged to prevent the progress of the resin crack, but on the other hand, the function of the raised portion RI for securing the mold resin filling passage may be hindered. A configuration in which no is provided is also suitable.

  In any configuration, the foremost surface of the primary bobbin 10 is formed in a U-shaped cross section surrounding the front surface 34 of the central core 30. Further, the holding bottom surface 13a has a central position cut out in a rectangular shape, thereby realizing a connection path of the conductor plate PT1 reaching the cut groove GV. The plate width of the conductor plate PT1 is substantially the same as the notch width of the holding bottom surface.

  Fixing pieces C1 and C2 are formed at positions above the outer surfaces of the holding side surfaces 13b and 13b to wind up the start and end of the primary winding 11, respectively. The fixed pieces C1 and C2 are in a positional relationship adjacent to both sides on the distal end side of the outer peripheral core 40.

  As shown in the circuit diagram of FIG. 3, the primary winding 11 wound around the fixed piece C1 needs to be electrically connected to the source terminal of the igniter TR, and the primary winding 11 wound around the fixed piece C2. Needs to be electrically connected to the cathode terminal of the diode D. Therefore, it is necessary to expose the conducting wire of the primary winding 11 near the fixed pieces C1 and C2, and for this purpose, a discharge path or a short circuit between the exposed conducting wire and the magnetic cores 30 and 40 having the ground potential is necessary. There is concern about the occurrence of resin cracks that become roads. In particular, in the case of a configuration in which the flange portion PR is omitted, the problem of resin cracks is important for the primary winding 11 exposed at the tip position of the primary bobbin body portion 12.

  However, in the present embodiment, the upper communication surface FA1 of the center core 30 is formed in an arc shape, and therefore, even if the flange portion PR is not present, there is a problem of resin cracks starting from the center core 30. Hateful.

<Outer peripheral core 40>
Next, the outer core 40 will be described with reference to FIG. As shown in FIG. 5 (a), in the outer peripheral core 40 of this embodiment, the main part of the main body STL (FIG. 5 (b)) made of an electromagnetic steel plate is covered with an elastic body ER in an adhesive state. As described above, the main body STL is configured by laminating a large number of thin U-shaped electromagnetic steel plates and integrating them by bonding or caulking.

  As the elastic body ER of this embodiment, a thermoplastic elastomer having a melting point (endothermic peak temperature) of 200 ° C. or higher is used, and more preferably, a thermoplastic polyether ester elastomer is used. Moreover, as an elastic body of an Example, the thing whose hardness in the temperature of 150 degreeC is evaluated by Shore D about 35D-50D is used, and it is about 0.5-1.0 mm thick. Is set.

  However, the elastic body ER of the present embodiment is not uniform in thickness, and is appropriately set corresponding to the covered portion of the main body portion STL. This will be described below including this point.

  As shown in FIG. 5 (a), the outer peripheral core 40 (main body portion STL) includes a flat core central portion 40a, a forward protruding portion 40b that protrudes downward substantially orthogonally from the tip of the core central portion 40a, and a core It is roughly divided into a rear protruding portion 40c that protrudes downward substantially orthogonally from the base end of the central portion 40a.

  The forward projecting portion (main body portion STL) 40b includes a flat front end surface 41 that extends straight downward, a flat rear surface 42 that approaches the front end surface as it goes downward, and a pair of side surfaces 43 that are substantially orthogonal to the front end surface and the rear surface 42. , And a lower communication surface FA2 having an arcuate outline that communicates the lowermost portion of the front end surface 41 and the rear surface 42.

  As shown in FIG. 2, the resin cover 3 is fitted in a contact state above the outer core 40. The front end surface 41 of the outer peripheral core 40 is close to the igniter TR arranged upside down, and the rear surface 42 of the outer peripheral core 40 is brought into contact with the front surface 34 of the central core 30 via the permanent magnet 50. ing.

  Further, the lower communication surface FA2 of the outer peripheral core 40 forms substantially the same plane as the core bottom surface BS of the central core, and is in contact with the conductor plate PT1 at the center position. Thus, the lower communication surface FA2 of the outer peripheral core 40 cannot be covered with the elastic body ER because it needs to contact the conductor plate PT1.

  The lower part of the lower contact surface FA2 is covered with the primary bobbin 10 and the conductor plate PT1, but the front part thereof is exposed to the igniter TR and the like, which may be a base point of the resin crack. Therefore, in this embodiment, the lower communication surface FA2 of the outer peripheral core 40 that must be exposed to the mold resin is processed into a predetermined arc shape to eliminate the right-angled corner, thereby avoiding the problem of the resin crack. Yes.

  As shown in FIG. 5, the core central part (main body part STL) 40a is formed in a flat plate shape having a predetermined width and a predetermined height. The upper surface SF is exposed, and the entire surface excluding the exposed surface SF is covered with an elastic body ER having a predetermined thickness (0.7 to 1.0 mm).

  Therefore, the thermal stress generated in the horizontal direction shown in FIG. 5 and the thermal stress generated in the downward direction where the secondary coil L2 is located are effectively buffered by the elastic body ER, and the occurrence of resin cracks can be prevented. However, there are concerns that a number of right-angled corners of the thin plate are aligned above the core central portion 40a, which becomes the base point of the crack.

  However, as shown in FIG. 2B, since the resin cover 3 is fitted in contact with the upper surface SF of the outer peripheral core 40, the resin cover 3 protects the resin crack. It does not occur. Note that the elastic body ER shown in FIG. 5 has a cut shape that avoids a right-angled corner with respect to the corner, and is not necessarily unclear, but the elastic body ER is located above the upper surface SF of the core central portion 40a. ER never exists. Therefore, in this embodiment, the outer core 40 is covered with the elastic body ER, but the height dimension of the ignition coil is not particularly increased.

  The proximal end portion of the forward projecting portion 40b is completely covered with an elastic body ER having a thickness of about 0.7 to 1.0 mm. On the other hand, the tip end portion of the forward projecting portion 40b is covered with the elastic body ER in which only the tip face 41 is bonded. As shown in FIG. 5 (c) and FIG. 5 (h), the elastic body ER has a thick-walled portion (wall thickness of about 0.7 to 1.0 mm) on the base end side and other thin-walled portions (wall thickness of 0.2 mm). 5 to 0.7 mm).

  Here, the thick region of the elastic body ER includes the proximal end portion of the forward projecting portion 40b and is mainly set corresponding to the arrangement position of the connection terminal of the igniter TR, and is cooled by thermal expansion and thermal contraction. By buffering the stress with the elastic body ER having a predetermined thickness (0.7 to 1.0 mm), the occurrence of the resin crack toward the connection terminal of the igniter TR is prevented.

  Moreover, the reason why the front end surface 41 of the outer peripheral core 40 is entirely covered is because the right-angle corners of the laminated electrical steel sheets are aligned on the front end surface 41. That is, when the front end surface 41 is viewed from the direction of the igniter TR, microscopically, there are right-angled corners for each thin plate. By covering all the right-angled corners with the elastic body ER, the base point of the resin crack Is prevented. In this embodiment, the pair of side surfaces 43 orthogonal to the distal end surface 41 are exposed to the mold resin except for the base end portion, but all or the main portions thereof are covered with the elastic body ER. It is also suitable.

  Next, the rear projecting portion (main body portion STL) 40c includes a bent contact surface 44 corresponding to the shape of the proximal end contact portion 33 of the central core 30, an outer surface 45 extending downward facing the coil case, The inner surface 46 extends downward in the vicinity of the secondary coil, and a pair of side surfaces 47 and 47 that communicate the outer surface and the inner surface.

  When the rear projecting portion (main body portion STL) 40c is evaluated in the covering state of the elastic body ER, the rear projecting portion 40c is almost entirely covered with the base end portion covered with the elastic body ER and the elastic body ER. Not divided into tips. The proximal end portion of the rearward projecting portion 40c is almost entirely covered with a thick (approximately 0.7 to 1.0 mm) elastic body. Covered in an H shape. Therefore, the open window 48 and the open surface 49 are formed on the outer surface 45 above and below the thick elastic body ER.

  However, since the opening window 48 is a portion where the peripheral edge of the resin cover 3 is engaged and is entirely covered with the resin cover 3, there is no possibility that a resin crack will occur from the opening window 48.

In addition, since the open surface 49 is almost entirely concealed by the contact of the ground potential conductor plate PT2, there is no particular problem. However, a gap (filled region of mold resin) corresponding to the thickness of the folded conductor plate PT2 is generated outside the conductor plate PT2 (vertical direction in FIG. 2A). Therefore, in order to prevent the occurrence of resin cracks that reach the secondary coil L2 and the like via the gap, elastic bodies ER are bonded to both sides of the open surface 49, and the thermal stress generated in the surface direction is buffered. Has been.
<Resin cover 3>
FIG. 6 is a view showing the resin cover 3 that covers the upper surfaces of the outer peripheral core 40 and the igniter TR. The resin cover 3 is an integrally molded product made of PBT resin having a plate thickness of about 0.65 to 9.5 mm, and a shallow box-shaped cover body 3a and a flange portion (attachment portion) 3b having a J-shaped cross section are integrated. It is configured. As shown in the figure, the uppermost surfaces of the cover main body 3a and the flange portion 3b form substantially the same plane.

  The inner peripheral surface of the cover main body 3a substantially matches the outer dimension of the upper portion of the outer core 40, and is configured to receive the upper portion of the outer core 40 and fit slightly tightly (see FIG. 2). And the protrusion 3c for press-fitting in a coil case is formed in the outer peripheral surface of a back side, and the insulation with the connection terminal of igniter TR is improved by forming the front peripheral edge a little deeply. . Moreover, the collar part 3b is connected with the cover main body 3a using the slightly deep front side periphery.

  And the collar part 3b is preventing the progress of the resin crack which goes upwards and diagonally upwards from the connection terminal of igniter TR because the front is bent below.

  As described above, in this embodiment, the occurrence of resin cracks and the progression thereof are effectively prevented by applying various devices to each member constituting the ignition coil. However, the specific configurations described in the embodiments are not intended to limit the present invention, and can be appropriately modified without departing from the spirit of the invention.

10 primary bobbin 11 primary winding L1 primary coil 20 secondary bobbin 21 secondary winding L2 secondary coil 30 central core 40 outer core TR igniter PG ignition plug 60 energizing part 1 coil case CL ignition coil 40a core central part 40b first Protruding part ER Elastic body 3 Cover body

Claims (9)

A primary coil with a primary winding wound around a primary bobbin, a secondary coil with a secondary winding wound around a secondary bobbin into which the primary coil is inserted, a central core inserted into the primary bobbin, and a secondary coil An outer core that is in contact with the central core to form a closed magnetic path in a state including a part of the outer core, an igniter that is arranged adjacent to the outer side of the outer core and controls energization of the primary coil, and an output voltage of the secondary coil. An ignition coil for an internal combustion engine that is configured such that each member is accommodated in a coil case filled with a thermosetting resin.
The outer peripheral core is configured to include a core central portion disposed above the secondary coil, and a first protrusion that protrudes downward from one end of the core central portion and faces the igniter,
The surface of the first protrusion facing the igniter is covered with an elastic body in contact,
An ignition coil for an internal combustion engine, wherein a cover body having a size for concealing the igniter and the outer core in a plan view is disposed on the igniter and the outer core.   2. The internal combustion engine according to claim 1, wherein the cover body is configured by integrating a box-shaped main body portion covering the uppermost portion of the outer peripheral core and a bent plate-shaped appendage portion covering the uppermost portion of the igniter. Ignition coil.   The ignition coil for an internal combustion engine according to claim 2, wherein an uppermost surface of the main body portion of the cover body and the attachment portion of the cover body form substantially the same plane.   The ignition coil for an internal combustion engine according to any one of claims 1 to 3, wherein the coil case is filled with a thermosetting resin in a state where a main body portion and an attachment portion of the cover body are exposed.   The ignition coil for an internal combustion engine according to any one of claims 1 to 4, wherein the cover body is made of PBT, and the main body is formed in a substantially rectangular shape in plan view. The outer peripheral core is configured to have a second projecting portion projecting downward from the other end portion of the core central portion,
6. The outer peripheral core is formed by laminating a plurality of thin U-shaped electromagnetic steel plates integrally forming the core central portion, the first projecting portion, and the second projecting portion. An ignition coil for an internal combustion engine according to claim 1. While the core central portion of the outer peripheral core is partially covered with a contact elastic body,
The ignition coil for an internal combustion engine according to any one of claims 1 to 6, wherein the uppermost surface of the elastic body and the uppermost surface of the outer peripheral core form substantially the same plane and receive the cover body.   The ignition coil for an internal combustion engine according to any one of claims 1 to 7, wherein the elastic body has a thickness of 0.5 to 1.0 mm.   The ignition coil for an internal combustion engine according to any one of claims 1 to 8, wherein the elastic body has a hardness at a temperature of 150 ° C of 35D to 50D as evaluated by Shore D.

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