JP2018152473A - Ignition coil of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectangular ignition coil in which miniaturization, weight reduction, and good insulation are achieved.SOLUTION: An ignition coil 20 comprises: a coil body 34, an igniter 36; a case 32 which accommodates the coil body 34 and the igniter 36 and has an open upper surface; and a gap filling material 38 filling a gap inside the case 32. The igniter 36 comprises: a box-shaped element built-in portion 62; and a plurality of terminals 64 protruding downward from the lower surface of the element built-in portion 62. The case 32 of the ignition coil 20 has recesses 42 at two corner portions close to the igniter 36 from among the corners on the bottom surface side. The terminal 64 of the igniter 36 is located inside the case 32 between the two recesses 42.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an ignition coil for an internal combustion engine.

  As a typical ignition coil for an internal combustion engine, there are a “pen type” in which the coil portion is accommodated in the plug hole of the engine and a “rectangular type” in which the coil portion is disposed on the plug hole. While the pen-type ignition coil is suitable for space saving, the coil structure is limited by the shape and size of the plug hole. With higher performance and lower fuel consumption of engines in recent years, higher output voltage is required for ignition coils. In recent years, rectangular ignition coils that have a degree of freedom in shape and can easily cope with high output voltage have been widely used.

  In manufacturing a rectangular ignition coil, a coil body including a primary coil, a secondary coil, and an iron core, and an igniter that performs current control of the primary coil are prepared. In this ignition coil, a coil body and an igniter are accommodated in a box-shaped case whose upper surface is open. FIG. 6 shows a state in which the igniter 4 is accommodated in the case 6 in the conventional ignition coil 2. In this figure, a cross section of the case 6 and the igniter 4 are shown. The igniter 4 includes a box-shaped element built-in portion 8 and a plurality of terminals 10. The igniter 4 is stored in the case 6 so that the element built-in portion 8 is positioned below the terminal 10.

  A gap generated inside the case 6 when the coil body and the igniter 4 are accommodated in the case 6 is filled with a gap filling made of a thermosetting resin. The secondary coil that generates a high voltage is insulated from the outside by the gap filling. An example of a rectangular ignition coil is disclosed in Japanese Patent Application Laid-Open No. 2014-179459.

Japanese Patent Laid-Open No. 2014-179459

  As the demand for smaller and lighter engines increases, the ignition coil is required to be smaller and lighter. This requirement is particularly strong for a rectangular ignition coil in which a coil portion is disposed on a plug hole. On the other hand, the ignition coil is required to have excellent insulation performance as the output voltage increases. In order to achieve miniaturization and weight reduction and excellent insulation performance, it has become a major issue to reliably fill the gaps inside the case with gap fillings.

  An object of the present invention is to provide a rectangular ignition coil that has been reduced in size, weight, and good insulation.

  An ignition coil according to the present invention includes a coil body with a built-in coil, an igniter, a case in which the coil body and the igniter are accommodated and an upper surface is opened, and a thermosetting resin that fills a gap in the case. And a gap filling. The igniter includes a box-shaped element built-in portion and a plurality of terminals protruding downward from the lower surface of the element built-in portion. The case has depressions in two corner portions adjacent to the igniter among the corners on the bottom surface side. Between the two depressions, the igniter terminal is located inside the case.

  Preferably, the width Wt of the terminal portion of the igniter is smaller than the width Wb of the element built-in portion. A width Wc inside the case between the two depressions is smaller than the width Wb.

  Preferably, the case includes a base portion and a resin injection enclosure protruding upward from the base portion in the vicinity of the igniter.

  Preferably, the material of the gap filling material is an epoxy resin.

  In the ignition coil according to the present invention, the terminal of the igniter is stored in the case so as to protrude downward from the lower surface of the element built-in portion. That is, unlike the conventional ignition coil shown in FIG. 6, the element built-in portion is located above the igniter terminal. In the manufacture of the ignition coil, the gap filling is poured from above the igniter. In this ignition coil, since the element built-in portion having a volume larger than that of the terminal is located above the case, the gap between the igniter and the case is small above the case. When the gap filling is poured, the liquid level of the gap filling rises compared to the conventional case. Furthermore, in this ignition coil, the case has depressions at two corners close to the igniter among the corners on the bottom side, and the igniter terminal is located inside the case between these depressions. ing. This depression reduces the volume of the case near the igniter. When the gap filling is poured, the liquid level of the gap filling rises. In this ignition coil, the liquid level of the gap filling is effectively increased by combining the element built-in portion on the upper side of the terminal and the case where the two recesses are provided in the case and the terminal is positioned therebetween. . This increases the pressure at which the liquid gap filler flows into the gap in the case. In this ignition coil, even in a miniaturized case, the internal gap can be efficiently and completely filled with the gap filler. Furthermore, voids remaining in the gap filling are suppressed. As a result, the ignition coil achieves high withstand voltage and high quality insulation performance while achieving miniaturization and weight reduction.

FIG. 1 is a perspective view illustrating an ignition coil according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the ignition coil shown in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a perspective view illustrating an ignition coil according to another embodiment of the present invention. FIG. 6 is a cross-sectional view showing a part of a conventional ignition coil.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 shows an ignition coil 20 according to an embodiment of the present invention. The ignition coil 20 is rectangular. In FIG. 1, an arrow X represents the front of the ignition coil 20. The reverse is backwards. An arrow Y represents the right direction of the ignition coil 20. The reverse is the left direction. An arrow Z represents the upward direction of the ignition coil 20. The reverse is the downward direction. FIG. 2 is an exploded perspective view of the ignition coil 20 of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. The arrows X, Y and Z have the same meaning in FIGS. The ignition coil 20 includes a main body 22, a connector part 24, a flange part 26, and a high voltage output part 28.

  The main body 22 is located at the center of the ignition coil 20. The main body 22 has a box shape. As shown in FIG. 1-4, the main body 22 of the ignition coil 20 includes a case 32, a coil body 34, an igniter 36, and a gap filler 38. In FIG. 2, the gap filler 38 is omitted. In FIG. 4, only the cross section of the case 32 and the igniter 36 are shown.

  As shown in FIG. 2, the case 32 has a hollow box shape. The case 32 has an upper surface opened. The connector portion 24 extends from the front surface 40 of the case 32, the flange portion 26 extends from the rear surface of the case 32, and the high voltage output portion 28 extends from the bottom surface of the case 32. In this embodiment, the case 32 is formed integrally with the connector portion 24, the flange portion 26, and the high voltage output portion 28.

  As shown in FIGS. 2 and 4, the case 32 has depressions 42 at two corner portions close to the igniter 36 among the corners on the bottom surface side. That is, the case 32 has a recess 42 at the front left lower corner portion and the front lower right corner portion. In the portion between these two depressions 42 (referred to herein as the case front lower portion 44), the width of the case 32 is narrower than the width of the upper portion thereof. The case 32 is made of resin. PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), and PET (polyethylene terephthalate) are exemplified as preferable materials for the case 32.

  As shown in FIGS. 2 and 3, the coil body 34 is accommodated in the case 32. The coil body 34 includes a primary coil 46, a bobbin 48, a secondary coil 50, an I-shaped iron core 52, an outer peripheral iron core 54, and a cap 56. The primary coil 46 is formed by winding a primary wire 58. FIG. 3 shows a cross section of the wound primary wire 58. A bobbin 48 is provided outside the primary coil 46. The secondary coil 50 is formed by winding a secondary wire 60 around the bobbin 48. Typically, the number of turns of the secondary wire 60 is 100 times or more the number of turns of the primary wire 58. As will be described later, a high voltage is generated in the secondary coil 50. A typical material of the primary wire 58 and the secondary wire 60 is copper (Cu).

  As shown in FIG. 3, the I-shaped iron core 52 penetrates the center of the primary coil 46 back and forth. The outer peripheral iron core 54 extends from one end of the I-shaped iron core 52 to the other end of the I-shaped iron core 52 through the upper side of the secondary coil 50. The I-shaped iron core 52 and the outer peripheral iron core 54 form an iron core loop. The I-shaped iron core 52 and the outer peripheral iron core 54 are typically made of silicon steel. The cap 56 is put on the upper surface of the outer peripheral iron core 54. The cap 56 prevents the outer peripheral iron core 54 from being exposed to the outside. The cap 56 is made of resin. PBT, PPS, and PET are illustrated as preferable materials for the cap 56.

  As shown in FIG. 2-4, the igniter 36 is accommodated in the case 32. As shown in FIGS. 2 and 3, the igniter 36 is located between the coil body 34 and the connector portion 24. The igniter 36 includes an element built-in portion 62 and a plurality of terminals 64. In this embodiment, the igniter 36 includes six terminals 64. The element built-in portion 62 has a box shape. Each terminal 64 protrudes downward from the lower surface of the element built-in portion 62. In other words, the igniter 36 is stored in the case 32 so that the element built-in portion 62 is located above the terminal 64. Some of the terminals 64 are electrically connected to connector terminals 66 described later. Some terminals 64 are electrically connected to the primary coil 46.

  In this specification, a rectangular region that surrounds all the terminals 64 (a rectangle that surrounds the left end of the leftmost terminal 64, the right end of the rightmost terminal 64, the upper end of the terminal 64, and the lower end of the longest terminal 64). Is referred to as a terminal portion 70 of the igniter 36. As shown in FIG. 4, in the ignition coil 20, the terminal portion 70 of the igniter 36 is located between the recesses 42 provided in the two corner portions of the case 32, which are close to the igniter 36. The terminal portion 70 of the igniter 36 is located between the recess 42 in the front left corner portion and the recess 42 in the lower right corner portion. That is, the terminal portion 70 of the igniter 36 is positioned inside the case front lower portion 44.

  In FIG. 4, a double arrow Wb indicates the width of the element built-in portion 62 of the igniter 36. A double arrow Wt indicates the width of the terminal portion 70 of the igniter 36. Specifically, the width Wt is the width between the left end of the terminal 64 located on the leftmost side and the right end of the terminal 64 located on the rightmost side. As shown in the figure, the width Wt is smaller than the width Wb.

  In FIG. 4, a double-headed arrow Wc represents the inner width of the case front lower portion 44. In the ignition coil 20, the width Wc is a width corresponding to the width Wt of the terminal portion 70. In the ignition coil 20, the width Wc is smaller than the width Wb. In this ignition coil 20, since the terminal portion 70 having a smaller width than the element built-in portion 62 is located inside the lower case front portion 44, the width Wc is also smaller than the width Wb.

  The gap filler 38 fills a gap generated inside the case 32 when the coil body 34 and the igniter 36 are accommodated in the case 32. The gap filling 38 is made of a thermosetting resin. As shown in FIG. 3, the gap filler 38 fills the gap between the inner wall of the case 32 and the coil body 34 and the igniter 36. Further, the gap filler 38 fills the gap between the secondary coil 50 and the outer peripheral iron core 54 inside the coil body 34. The gap filling 38 insulates the secondary coil 50 in which a high voltage is generated from other members. For this reason, a thermosetting resin excellent in insulation performance is selected as the material of the gap filling 38. Further, in order to fill all the gaps in the case 32 with resin, a thermosetting resin having a low viscosity is selected as the material of the gap filling 38.

  The connector part 24 is located in front of the main body 22. The connector part 24 includes a cylindrical part 72 and four blade parts 74 positioned at the top, bottom, left and right of the cylindrical part 72 at the root of the cylindrical part 72. In FIGS. 1 and 2, the blade portion 74 located above and to the left of the cylindrical portion 72 is shown. The connector portion 24 is opened at the front. As shown in FIG. 3, the connector portion 24 includes a connector terminal 66 on the inner side. Although not shown, the plurality of connector terminals 66 are juxtaposed in the left-right direction. When the ignition coil 20 is mounted on the vehicle, the connector terminal 66 is connected to a vehicle control unit (ECU). As described above, the connector terminal 66 is also connected to the terminal 64 of the igniter 36.

  The flange portion 26 is located behind the main body 22. The flange portion 26 is provided with a hole 76 penetrating vertically. Although not shown, the ignition coil 20 is fixed to the engine by passing a bolt through the hole 76 and a hole provided in the engine. The ignition coil 20 is firmly fixed to the engine by the flange portion 26.

  The high voltage output unit 28 is located below the main body 22. Although not shown, the high voltage output unit 28 includes a high voltage terminal therein. This high voltage terminal is connected to the terminal of the secondary coil 50. Although not shown, when the ignition coil 20 is mounted on the vehicle, the high voltage output unit 28 is inserted into the plug hole. The high voltage terminal is connected to the spark plug.

  The operation of the ignition coil 20 is as follows. A control signal from the vehicle control device is sent to the igniter 36 via the connector terminal 66. The igniter 36 is a switch that controls conduction and disconnection of the current of the primary coil 46. In accordance with the control signal, the igniter 36 conducts or disconnects the current of the primary coil 46. As described above, since the number of turns of the secondary wire 60 is 100 times or more the number of turns of the primary wire 58, a high voltage of several tens of kV is generated in the secondary coil 50 due to a change in the current of the primary coil 46. The high voltage generated in the secondary coil 50 is applied to the spark plug through the high voltage output unit 28. This ignites the gasoline. The control device controls the timing for igniting gasoline through the spark plug.

  In manufacturing the ignition coil 20, a case 32, a coil body 34, and an igniter 36 are prepared. As shown in FIG. 2, the case 32 is formed integrally with the connector portion 24, the flange portion 26, and the high voltage output portion 28. As shown in FIG. 2, the coil body 34 and the igniter 36 are accommodated in the case 32. The coil body 34 and the igniter 36 are set at predetermined positions inside the case 32. The igniter 36 is set so that the terminal portion 70 is positioned inside the case front lower portion 44. A terminal 64 of the igniter 36 is connected to the connector terminal 66 and the primary coil 46. A liquid gap filling 38 is filled in the case 32. The gap filling 38 is poured from the upper side of the front portion of the case 32 (that is, the upper portion of the igniter 36). The gap filler 38 is poured until the liquid level of the gap filler 38 reaches a predetermined height. Thereafter, the gap filling 38 is heated and cured. Thus, the ignition coil 20 is obtained.

  Hereinafter, the function and effect of the present invention will be described.

  In the ignition coil 20 according to the present invention, the terminal 64 of the igniter 36 is stored in the case 32 so as to protrude downward from the lower surface of the element built-in portion 62. That is, unlike the conventional ignition coil 2 shown in FIG. 6, the element built-in portion 62 is located above the terminal 64 of the igniter 36. In the manufacture of the ignition coil 20, the gap filling 38 is poured from above the igniter 36. In the ignition coil 20, since the element built-in portion 62 having a larger volume than the terminal 64 is positioned above the case 32, the gap between the igniter 36 and the case 32 is small above the case. When the gap filling 38 is poured, the liquid level of the gap filling 38 rises as compared with the conventional case.

  Further, in this ignition coil 20, the case 32 has depressions 42 at two corners close to the igniter 36 among the corners on the bottom surface side, and between these depressions 42, the inside of the case 32. The terminal 64 of the igniter 36 is located. The recess 42 reduces the volume of the case 32 in the vicinity of the igniter. When the gap filling 38 is poured, the liquid level of the gap filling 38 further rises. By combining the element built-in portion 62 on the upper side of the terminal 64 and the case 32 provided with the two depressions 42 and the terminal 64 positioned therebetween, the ignition coil 20 has a liquid in the gap filling 38. The surface rises effectively. This increases the pressure at which the liquid gap filler 38 flows into the gap in the case 32. In the ignition coil 20, even in the downsized case 32, the gaps inside the case 32 can be efficiently and completely filled with the gap filler 38. Furthermore, the void is suppressed from remaining in the gap filling 38. Thereby, in this ignition coil 20, after achieving miniaturization and weight reduction, high withstand voltage and high quality insulation performance is realized.

  As described above, in the conventional ignition coil 2, the igniter 4 is stored in the case 6 so that the element built-in portion 8 is positioned below the terminal 10. The element built-in portion 8 of the igniter 4 exists inside the front lower portion 14 of the case. For this reason, as shown in FIG. 6, the inner width Wc of the case front lower portion 14 cannot be made equal to or smaller than the width Wb of the element built-in portion 8.

  In the ignition coil 20, the terminal portion 70 of the igniter 36 is located below the element built-in portion 62. The width Wt of the terminal portion 70 of the igniter 36 is smaller than the width Wb of the element built-in portion 62. In the ignition coil 20, the terminal portion 70 having a small width is positioned inside the case front lower portion 44. Thereby, in this ignition coil 20, the width Wc inside the case front lower portion 44 is made smaller than the width Wb of the element built-in portion 62. In the ignition coil 20, the width of the lower front portion 44 of the case is smaller than that of the conventional ignition coil 2. This further raises the liquid level of the gap filling 38 when the gap filling 38 is poured. This further increases the pressure at which the liquid gap filler 38 flows into the gap in the case 32. In the ignition coil 20, the gap inside the case 32 can be efficiently and completely filled with the gap filler 38.

  As described above, in the ignition coil 20, the width of the lower front part 44 of the case is smaller than that of the conventional ignition coil 2. This contributes to the reduction in size and weight of the ignition coil 20. The ignition coil 20 is smaller and lighter than the conventional ignition coil 2.

  The material of the gap filling 38 is preferably an epoxy resin. Epoxy resin has high insulation performance. The epoxy resin enables insulation of the high voltage portion of the secondary coil 50 with a small volume. This contributes to downsizing of the ignition coil 20. Thereby, miniaturization and excellent insulation performance are realized. Furthermore, the viscosity of the epoxy resin before curing is low. The gap filling material 38 can be spread to every corner of the gap in the case 32. It is suppressed that a void remains in the gap filling material 38. Thereby, in this ignition coil 20, high withstand voltage and high quality insulation performance is realized.

  FIG. 5 shows an ignition coil 80 according to another embodiment of the present invention. In FIG. 5, an arrow X represents the front of the ignition coil 80. The reverse is backwards. An arrow Y represents the right direction of the ignition coil 80. The reverse is the left direction. An arrow Z represents the upward direction of the ignition coil 80. The reverse is the downward direction. The ignition coil 80 is rectangular. The ignition coil 80 includes a main body 82, a connector portion 84, a flange portion 86, and a high voltage output portion 88. The main body 82 includes a case 92, a coil body 94, an igniter (not shown), and a gap filler 98. The ignition coil 80 is the same as the ignition coil 80 of FIG.

  As shown in FIG. 5, the case 92 includes a base portion 100 and a resin injection enclosure 102 that protrudes upward from the base portion 100. In FIG. 5, a two-dot chain line M represents a boundary between the base portion 100 and the resin injection enclosure 102. This two-dot chain line M corresponds to the position of the upper end of the case 32 of the ignition coil 20 of FIG. 1 that does not have the resin injection enclosure 102. As shown in FIG. 5, the resin injection enclosure 102 is located in front of the case 92 (that is, in the vicinity of an igniter not shown). The resin injection enclosure 102 forms a space for injecting the gap filler 98. The resin injection enclosure 102 is formed on the front surface 108 (connector portion 84) of the base portion 100 from the front side portion of one side surface 104 of the base portion 100 (surface extending in the front-rear direction from the ends of the left and right blade portions 106 of the connector portion 84). Of the base portion 100 and the front side portion of the other side surface of the base portion 100.

  As described above, the gap filling 98 is poured from above the igniter. By providing the resin injection enclosure 102 in the vicinity of the igniter, the height of the liquid level when the gap filling material 98 is poured can be increased. This increases the pressure at which the liquid gap filler 98 flows into the gap in the case 92. In this ignition coil 80, the gap inside the case 92 can be efficiently and completely filled with the gap filler 98. Furthermore, voids are suppressed from remaining in the gap filling 98. Thereby, in this ignition coil 80, high withstand voltage and high quality insulation performance is realized.

  In FIG. 5, the double arrow H represents the height of the resin injection enclosure 102. The height H is preferably 2 mm or more. By setting the height H to 2 mm or more, the height of the liquid surface when the gap filling material 98 is poured can be effectively increased. In this ignition coil 80, the gap inside the case 92 can be more efficiently and completely filled with the gap filling 98. It is more effectively suppressed that voids remain in the resin. Thereby, in this ignition coil 80, high withstand voltage and high quality insulation performance is realized. The height H is preferably 5 mm or less. By setting the height H to 5 mm or less, the resin injection enclosure 102 is unlikely to become an obstacle when the ignition coil 80 is used. Further, an increase in mass due to the resin injection enclosure 102 is suppressed.

  In FIG. 5, a double-headed arrow L represents the length from the front end to the rear end of the resin injection enclosure 102 measured in the front-rear direction. The length L is preferably 2 mm or more. By setting the length L to 2 mm or more, the height of the liquid surface when the gap filling material 98 is poured can be effectively increased. In this ignition coil 80, the gap inside the case 92 can be more efficiently and completely filled with the gap filling 98. It is more effectively suppressed that voids remain in the resin. Thereby, in this ignition coil 80, high withstand voltage and high quality insulation performance is realized. The length L is preferably 10 mm or less. By setting the length L to 10 mm or less, the resin injection enclosure 102 is unlikely to get in the way when the ignition coil 80 is used. Further, an increase in mass due to the resin injection enclosure 102 is suppressed.

  As described above, according to the present invention, it is possible to obtain an ignition coil that has been reduced in size, reduced in weight, and achieved good insulation. From this, the superiority of the present invention is clear.

  The ignition coil described above is used for various internal combustion engines.

2, 20, 80 ... ignition coil 4, 36 ... igniter 6, 32, 92 ... case 8, 62 ... element built-in part 10, 64 ... terminal 12, 42 ... depression 14 44, lower case front part 22, 82 ... main body 24, 84 ... connector part 26, 86 ... flange part 28, 88 ... high voltage output part 34, 94 ... coil body 38, 98 ... Gap filling 40 ... Front surface of case 46 ... Primary coil 48 ... Bobbin 50 ... Secondary coil 52 ... I-shaped iron core 54 ... Outer iron core 56 ...・ Cap 58... Primary wire 60 .. Secondary wire 62... Secondary wire 66... Connector terminal 70... Terminal portion 72, 110. 76 ... Hole 100 ... Base 102 ... Resin Needful enclose 104 ... side 108 ... Front

Claims (4)

A coil body with a built-in coil, an igniter, a case in which the coil body and the igniter are accommodated and an upper surface is opened, and a gap filling made of a thermosetting resin filling the gap inside the case are provided. ,
The igniter includes a box-shaped element built-in part and a plurality of terminals protruding downward from the lower surface of the element built-in part,
The case has a depression in two corners close to the igniter among the corners on the bottom side,
An ignition coil for an internal combustion engine, wherein the terminal of the igniter is located inside the case between the two depressions. The width Wt of the terminal portion of the igniter is smaller than the width Wb of the element built-in portion,
The ignition coil according to claim 1, wherein a width Wc inside the case between the two depressions is smaller than the width Wb.   3. The ignition coil according to claim 1, wherein the case includes a base portion and a resin injection enclosure protruding upward from the base portion in the vicinity of the igniter.   The ignition coil according to any one of claims 1 to 3, wherein a material of the gap filling is an epoxy resin.

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