JP2006179597A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil capable of obtaining an output of best ignition performance, in which it has long life span and high reliability which is easy to assemble, and which has versatility such as mounting the ignition coil on highly reliable and versatile engines. <P>SOLUTION: A space is provided in the lower part of a case at a portion where a primary voltage input is fitted to the case, and a case lower end is protruded axially in its outer diameter end on the side of a high pressure tower. An annular recess having a smaller diameter than a cylinder outer diameter is formed peripherally on the periphery of the cylinder of the case located more axially frontally than the tip end of the outer diameter end, and a protruded part is provided on the part of an umbrella in an outer configuration peripheral direction below the upper housing of the case such that it protrudes in the direction of the upper housing. Also, a rain cover in close contact with the umblerra has a protruded part such that it protrudes in the direction of the upper housing so as to match the above situation. Further, there is provided an air vent hole in the protruded part, and an outer diameter of plug boots at the upper end of the same and the inner diameter of the case at the lower end of the same are made equal to each other, and the upper end of the plug boots gets into an inner diameter side of the case lower end. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

   The present invention relates to an ignition coil for a cylindrical internal combustion engine that supplies a high voltage to an ignition plug, and particularly accommodated in a plug hole of an engine head.

  The ignition coil used in a recent automobile internal combustion engine has conflicting demands for downsizing and higher output to cope with a lean combustion engine considering the global environment.

  Among them, the cylindrical internal combustion engine ignition coil that directly supplies a high voltage to the ignition plug of the engine accommodates a part or most of the ignition coil in the plug hole of the engine head, so that the space on the engine head can be reduced, In order to supply high voltage directly to the spark plug, there is no need for a conducting wire to the spark plug such as a high tension cable, so there is less noise during ignition that adversely affects the electrical components, and the ignition energy to the spark plug It is used in many engines because of its advantages such as low propagation loss.

  A conventional example will be described with reference to FIGS. 4 is a perspective view showing the appearance of a cylindrical ignition coil for an internal combustion engine to which the conventional technique is applied, FIG. 5 is a longitudinal sectional view of FIG. 4, and FIG. 6 is a cylinder for the internal combustion engine to which the conventional technique is applied. It is a figure showing the assembly direction of the primary bobbin of a type | mold ignition coil, and a case.

  4 to 6, the embodiment of the present invention is a polyphenylene sulfide (hereinafter referred to as “PPS”) having a large opening at the top and an opening at the bottom of the cylindrical shape, and having good electrical insulation characteristics. A cylindrical case 111 formed of a flame-retardant insulating resin material, and a primary coil 115 in which a primary copper wire is wound around a primary bobbin 114 formed of polybutylene terephthalate (hereinafter referred to as “PBT”) A section is provided by a plurality of flanges from one end to one end, and a secondary coil 117 in which a secondary copper wire is wound around a secondary bobbin 116 having a laminated winding in each section, and a central iron formed of a silicon steel plate or the like A cylindrical ignition coil 100 for an internal combustion engine having a core 118 and supplying a power supply voltage to the primary coil 115 to an upper housing part 111b having a large opening of the case 111. A primary voltage input portion 112 is attached, optionally on the primary current in the upper housing part 111b - for accommodating the igniter 113 to be turned off. In addition, the low pressure part and the high pressure part existing in the vicinity of the axial end part of the secondary bobbin 116 are provided with a plurality of flanges having a narrow-pitch section concentrated on the part, so that the bobbin due to stress during use is provided. Can be prevented from cracking and breaking. Further, a hole 111d for fitting with an engaging projection 114t of a primary bobbin described later is provided at the lower end of the cylindrical portion of the case 111. In the above, the upper storage portion 111b forms a terminal storage case, and the electrical connection between the igniter 113 and the terminal primary coil 115 is completed by simply attaching the igniter 113 to the upper storage portion 111b. Thus, no wiring routing or special connection process is required.

  In addition, the central iron core 118 and the secondary coil 117 coaxially with the central iron core 118 are disposed in the primary coil 115, and are formed in a cylindrical shape outside of the primary coil 115 and part of the circumference thereof. In some cases, two external iron cores 119 having notches are usually arranged. At this time, the cutout portions of the outer iron core 119 are alternately arranged at intervals of 180 °. At both ends of the central iron core 118, a magnetic flux generated in the primary coil 115 in order to suppress saturation of the magnetic flux of the iron core in the secondary coil 117 in which a secondary copper wire is wound around the secondary bobbin 116, A permanent magnet 121 that generates a magnetic flux in the opposite direction may be attached to both ends to increase ignition energy. These are referred to as a primary coil assembly 110.

  The bottom of the primary bobbin 114 has a high voltage tower 114a for supplying a high voltage generated by the secondary coil 117 to a spark plug (not shown), and has a secondary high voltage terminal 122 on the inner bottom of the high voltage tower 114a. An O-ring 141 for preventing leakage of the insulating casting material is mounted on the outer peripheral surface 114u of the high-pressure tower 114a, and the tip of the outer peripheral surface 114u protrudes radially outward at equal intervals of 180 °. A plurality of key-like engagement protrusions 114t are formed. Here, the high-pressure tower 114 a is configured to protrude from the end of the case when the case 111 is mounted.

  Next, when the above-described primary coil assembly 110 is assembled to the case 111, the two engaging protrusions 114t provided around the high-voltage tower 114a of the primary bobbin 114 are inserted from the upper opening of the case 111. The primary voltage input unit 112 and the primary coil assembly 110 are electrically connected at the same time as the holes 111d of the case 111 are fitted together. Further, the secondary high voltage terminal 122 is electrically connected to a conductive spring 23, and the high voltage tower portion 114a is made of rubber or the like having excellent electrical insulation so that a high voltage does not leak into a metal portion such as a plug hole. A molded plug boot 125 is attached to cover the spring 23. Further, below the upper storage portion 111b of the case 111, there is provided an umbrella portion that rapidly increases the diameter of the cylindrical portion that is the body of the case and rapidly decreases in diameter. When the ignition coil 100 is mounted on an engine head (not shown), a rain cover 126 formed of an elastically deformable rubber or the like that seals a plug hole (not shown) and the outside air is mounted on the cylindrical portion of the case 111. And placed in close contact with the umbrella portion below the upper storage portion 111b. Further, the rain cover 126 is provided with an air vent hole 127 that communicates with the plug hole when the ignition coil 100 is mounted, so that the pressure in the plug hole after the ignition coil 100 is mounted and the outside air are made uniform. Further, an insulating casting material is injected and filled from the opening at the top of the case 111 and cured to be insulated and sealed.

  When the ignition coil 100 is in operation, a primary current is input from the primary voltage input unit 112, the primary coil 115 is energized, and the magnetic energy generated in the primary coil 115 is generated by the central iron core 118 and the exterior iron core. 119 is propagated and a high voltage corresponding to the turn ratio of the primary coil 115 and the secondary coil 117 is generated in the secondary coil 117. The generated high voltage is sent from the secondary coil 117 through the secondary high voltage terminal 122 to the spark plug (not shown) connected to the spring 123 through the spring 123.

  In this way, the ignition coil 100 is isolated from the high voltage output portion, and the high voltage output portion is separated from the electrically low voltage member such as the primary coil 115, so that good insulation characteristics are maintained. The ignition coil 100 with high reliability can be provided.

In addition, the ignition coil 100 is assembled to the engine, but as a coil cover (not shown), the ignition coil 100 is entirely covered so as to directly protect against raindrops and the like.
JP2003-257755A

  However, in the above-described prior art, the ignition coil is injected and filled with an insulating casting material from the opening above the case 111 and cured and insulated and sealed, but the power supply voltage is supplied to the case 111 and the primary coil 115. There is a problem that the insulating casting material leaks by sewing the gap between the fitting groove with the primary voltage input unit 112 and the insulating casting material sags downstairs. Here, the fitting groove portion of the case 111 and the primary voltage input part 112 is doubled or more multiplexed, and the gap between the fitting grooves of the primary voltage input part 112 is sealed, thereby leaking the insulation casting material. Although the dashi may be prevented, the structure becomes complicated, so that the cost for the molding die is increased, the number of assembling steps is increased, and the working time is required. In addition, there is a problem that the lower end of the case 111 is cracked by the thermal stress that repeatedly expands and contracts over time in the engine room, but the thickness of the lower end of the case 111 is increased to compensate for the strength of the lower end of the case 111. If the thickness of the lower end is thick, the injection pressure cannot reach the lower end of the case 111 when forming the case 111, and a void is generated inside the lower end of the case 111. If a void is generated, good insulation cannot be maintained at the lower end of the case 111, which may lead to a leak failure due to poor insulation. In addition, the engine head on which the conventional ignition coil is mounted is provided with a coil cover (not shown) that covers the ignition coil to prevent drip and dust. However, when the ignition coil 100 is mounted on various engine heads, Such a coil cover may be unnecessary. In this case, liquid suitability such as rainwater drops directly on the mounting surface, and liquid suitability enters from the air vent hole 127 of the rain cover 126 against the splash of the water droplet. There is. PBT is a well-balanced resin material with good heat resistance and chemical resistance and high mechanical strength. However, when used continuously in an ozone atmosphere or in a steam atmosphere, hydrolysis or the like occurs, resulting in a continuous atmosphere. There is a problem that the mechanical strength of the PBT is lowered under the use environment. In the structure of the conventional case 111 and the primary bobbin 114 as shown in the figure, when the ignition coil 100 is mounted on the plug hole, the case 111 and the primary bobbin 114 are exposed to the atmosphere inside the plug hole. . When water droplets enter the plug hole, the inside of the plug hole may become a high-temperature steam atmosphere due to the high temperature caused by the engine start. Under such circumstances, the primary bobbin 114 with time may be hydrolyzed and deteriorated in the primary bobbin 114 of the PBT. In such a state, good insulation performance cannot be maintained, and in some cases, leakage due to insulation failure occurs.

  Therefore, in view of the above problems, the present invention is a cylindrical internal combustion engine ignition coil that is mounted in a plug hole of an engine and supplies a high voltage to an ignition plug, and has a long life, high reliability, and easy assembly. An object of the present invention is to provide an ignition coil capable of obtaining the output of the best ignition performance with versatility such as mounting the ignition coil in various engines.

  In order to solve the above-described problems, the present invention provides, in claim 1, a central iron core, a primary coil in which a primary winding is wound around a primary bobbin disposed coaxially with the central iron core, and 2 A secondary coil in which a secondary winding is wound around a secondary bobbin, an igniter that controls on / off of a primary current that flows through a primary coil of an ignition coil, a primary current input unit that supplies primary current to the igniter, A cylindrical case that accommodates the primary coil and the secondary coil, and the primary bobbin is formed from an outer periphery of a high-voltage tower section that supplies a high voltage generated by the secondary coil to the spark plug. In the ignition coil for a cylindrical internal combustion engine, in which the high voltage tower portion is accommodated and protruded in the cylindrical case, a frame is provided on the outer peripheral surface of the portion where the primary voltage input portion is fitted to the cylindrical case, The primary voltage input section is the cylindrical case. From scan mating surfaces, and an internal combustion engine for cylindrical ignition coil, characterized in that provided increased wide bottom. According to a second aspect of the present invention, a central coil, a primary coil in which a primary winding is wound around a primary bobbin disposed coaxially with the central core, and a secondary winding in a secondary bobbin are wound. A secondary coil; an igniter that controls on / off of a primary current flowing through the primary coil of the ignition coil; a primary current input unit that supplies the primary current to the igniter; and the primary coil and the secondary coil. The primary bobbin is formed from the outer periphery of a high-pressure tower portion that supplies a high voltage generated by a secondary coil to the ignition plug, and the high-pressure tower portion is accommodated in the cylindrical case. In the cylindrical internal combustion engine ignition coil projecting, the lower end of the case has an outer diameter end projecting in the axial direction toward the high-pressure tower, and the case lower end is positioned in front of the outer diameter end. On the outer periphery of the cylinder, the cylinder 3. An annular recess having a diameter smaller than the diameter is formed in the circumferential direction, and ribs protruding at equal intervals with respect to the outer periphery direction of the case are formed in the annular recess. It is set as the cylindrical ignition coil for internal combustion engines of description. According to a third aspect of the present invention, a central coil, a primary coil in which a primary winding is wound around a primary bobbin disposed coaxially with the central core, and a secondary winding in a secondary bobbin are wound. A secondary coil; an igniter that controls on / off of a primary current flowing through the primary coil of the ignition coil; a primary current input unit that supplies the primary current to the igniter; and the primary coil and the secondary coil. The primary bobbin is formed from the outer periphery of a high-pressure tower portion that supplies a high voltage generated by a secondary coil to the ignition plug, and the high-pressure tower portion is accommodated in the cylindrical case. In the cylindrical internal combustion engine ignition coil projecting, a convex portion is provided in a part of the outer circumferential direction of the umbrella portion below the upper storage portion of the case so as to protrude toward the upper storage portion. Plug hole and ignition carp The rain cover that is in close contact with the umbrella part that seals is also provided with a convex part so as to protrude in the direction of the upper storage part so as to match this, and an air vent hole that communicates with the plug hole is provided in the convex part of the rain cover. A cylindrical ignition coil for an internal combustion engine according to any one of claims 1 to 3. According to a fourth aspect of the present invention, a central coil, a primary coil in which a primary winding is wound around a primary bobbin arranged coaxially with the central core, and a secondary winding in a secondary bobbin are wound. A secondary coil; an igniter that controls on / off of a primary current flowing through the primary coil of the ignition coil; a primary current input unit that supplies the primary current to the igniter; and the primary coil and the secondary coil. The primary bobbin is formed from the outer periphery of a high-pressure tower portion that supplies a high voltage generated by a secondary coil to the ignition plug, and the high-pressure tower portion is accommodated in the cylindrical case. In the protruding cylindrical internal combustion engine ignition coil, the plug boot fitted with the spark plug has a smaller outer diameter on the side fitted with the case, and the outer diameter of the lower end of the case is the same as the inner diameter. And plug boot pair During attaching, the internal combustion engine for cylindrical ignition coil of claim 1 to claim 3, characterized in that was submerge a portion the upper end of the plug boot on the inner diameter side of the case bottom. The cylindrical ignition coil for an internal combustion engine according to any one of claims 1 to 4, further comprising: an upper storage portion having a large opening of the case for storing the igniter. . A sixth aspect of the present invention provides a cylindrical ignition coil for an internal combustion engine, which is a combination of at least two of the first to fifth aspects.

  If the said solution is used, the frame 12w will be provided in the outer peripheral surface of the location where the primary voltage input part 12 fits with the case 11, and the said frame 12w will be from the surface where the primary voltage input part 12 fits with the case 11. Since the lower part is widely provided, when the frame 12w and the primary voltage input part 12 are fitted, a space B in which the primary voltage input part 12 and the case 11 are not fitted can be set. As a result, the insulating casting material that has been sewed through the gap between the fitting groove between the case 111 and the primary voltage input unit 112 that has occurred in the past and leaked out is allowed and retained in the space B. With a simple structure, it is possible to prevent the leaked and insulative cast material from reaching downstairs. Further, the lower end of the case 11 has an outer diameter end projecting in the axial direction toward the high-pressure tower 14a, and the outer periphery of the cylinder of the case 11 positioned axially in front of the outer diameter end is smaller than the outer diameter of the cylinder. The annular recess C is formed in the circumferential direction, and the rib 11f protruding at equal intervals with respect to the outer peripheral direction of the case 11 is formed in the annular recess C. Therefore, the thickness of the lower end portion of the case 11 is thin. Thus, the injection pressure can reach the lower end of the case 11 when the case 11 is molded, and the void at the lower end portion of the case 11 which has been generated conventionally does not occur. Moreover, since the rib 11f formed in the annular recessed part C of the case 11 has a reinforcing effect on the lower end of the case 11, the lower end strength of the case 11 can be improved. Therefore, a good insulation state of the case 11 can be maintained by this synergistic effect, and leakage due to poor insulation does not occur. Further, a convex portion A is provided in a part of the outer circumferential direction of the umbrella portion 11h below the upper storage portion 11b having a large opening of the case 11 so as to protrude in the direction of the upper storage portion 11b, and is closely attached to the umbrella portion 11h. The rain cover 26 to be provided is also provided with a convex portion A so as to protrude in the direction of the upper storage portion 11b so as to match this, and an air vent hole 27 is provided in the convex portion A. Thus, by setting the air vent hole 27 position of the rain cover 26 upward from the outer peripheral surface height position of the umbrella portion 11h, the possibility of entering liquid is further reduced. Further, since the outer diameter of the upper end of the plug boot 25 is reduced to the same diameter as the inner diameter of the lower end of the case 11, when the case 11 and the plug boot 25 are assembled, the upper end of the plug boot 25 is set to the inner diameter of the lower end of the case 11. You can dive into the side. As a result, the primary bobbin 14 is completely covered in the plug boot 25, so that hydrolysis degradation of the primary bobbin 14 made of PBT occurs in a plug hole under an environment such as a high-temperature steam atmosphere or ozone. do not do. Therefore, good insulation performance can be continuously maintained.

  With the above-described configuration of the present invention, it is possible to prevent the leaked and insulative cast material from reaching the downstairs with a simple structure. Good insulation at the lower end of the case 11 can be maintained, and leakage due to poor insulation does not occur. Further, by raising and changing the position of the air vent hole 27 of the rain cover 26 in the upward direction, the possibility of liquid entry is reduced. Further, since the primary bobbin 14 is completely covered in the plug boot 25, good insulation performance can be continuously maintained even in a plug hole under a high-temperature steam atmosphere or an environment such as ozone. Therefore, it has long life, high reliability, easy assembly, high reliability, versatility such as mounting the ignition coil 1 on various engines, etc. A coil can be provided.

  Next, only different portions of the ignition coil according to the embodiment of the present invention and the background art will be described. An embodiment according to the present invention will be described with reference to FIGS. 1 is a perspective view showing the appearance of a cylindrical ignition coil for an internal combustion engine to which the technology of the present invention is applied, FIG. 2 is a longitudinal sectional view of FIG. 1, and FIG. 3 is a sectional view of a high-pressure tower portion of FIG. It is.

  1 to 3, according to the embodiment of the present invention, a primary copper wire is wound around a cylindrical case 11 having a large opening in the upper part and an opening in the cylindrical lower part, and a primary bobbin 14. A cylindrical ignition coil for an internal combustion engine having a primary coil 15, a secondary coil 17 in which a secondary copper wire is wound around a secondary bobbin 16, and a central iron core 18 formed of a silicon steel plate or the like. A primary voltage input unit 12 for supplying a power supply voltage to the primary coil 15 is mounted on the upper housing part 11b having a large opening of the case 11, and an igniter for turning on and off the primary current to the upper housing part 11b. 13 is stored. Further, a hollow 11d that fits with an engaging protrusion 14t of a primary bobbin 14 described later is provided on the inner peripheral side of the cylindrical portion tip of the case 11. The upper storage portion 11b forms a terminal storage case, and the electrical connection between the igniter 13 and the terminal primary coil 15 is completed by simply mounting the igniter 13 on the upper storage portion 11b. There is no need for wiring routing or special connection processes.

  The bottom of the primary bobbin 14 has a high voltage tower 14a for supplying a high voltage generated by the secondary coil 17 to a spark plug (not shown), and a secondary high voltage terminal 22 is provided on the inner bottom of the high voltage tower 14a. An O-ring 41 that prevents leakage of the insulating casting material is attached to the outer peripheral surface 14u of the high-pressure tower 14a, and the tip of the outer peripheral surface 14u protrudes radially outward at equal intervals of 180 °. A plurality of key-like engaging projections 14t are formed. Here, the high-pressure tower portion 14 a protrudes from the end portion of the case 11 when the case 11 is mounted. The lower end of the case 11 has an outer diameter end protruding from the base of the high pressure tower portion 14a toward the axial high pressure tower portion 14a, and the outer periphery of the cylinder of the case 11 positioned in front of the distal end of the outer diameter end An annular recess C having a diameter smaller than the diameter is formed in the circumferential direction, and ribs 11f protruding at equal intervals are formed in the annular recess C. Thus, a space B covering the lower end of the case 11 is formed at the base of the high-pressure tower portion 14a. In the above case, the case 11 is provided with a frame 12w having a large lower portion on the outer peripheral surface on the case 11 side where the primary voltage input unit 12 is fitted to the case 11, and the frame 12w includes the primary voltage input unit. The lower part is wider and larger than the surface where 12 is fitted to the case 11. Further, the lower end portion of the case 11 has a thin thickness at the lower end portion of the case 11 and is arranged at equal intervals in the outer peripheral direction of the case 11, and reinforcing ribs 11 f protruding from the outer peripheral surface of the case 11 are formed on the case 11. . Further, a convex portion is provided on a part of the outer circumferential direction of the umbrella portion 11h below the upper storage portion 11b of the case 11 so as to protrude in the direction of the upper storage portion 11b. Further, the rain cover 26 that is in close contact with the umbrella portion 11h is also provided with a convex portion A so as to protrude in the direction of the upper storage portion 11b so as to match this, and the convex portion A is connected to the inside of the plug hole after the ignition coil is assembled to the engine. An air vent hole 27 that communicates with the outside atmosphere is provided. In addition, the plug boot 25 formed of rubber or the like excellent in electrical insulation so that a high voltage does not leak into a metal portion such as a plug hole has a smaller outer diameter at the upper end of the plug boot 26 fitted to the lower end of the case 11. The structure is the same as the inner diameter of the lower end of the case 11. Thus, when the case 11 and the plug boot 26 are assembled, the upper end of the plug boot 26 can be inserted into the space B of the attaching portion on the inner diameter side of the lower end of the case 11. Finally, an insulating casting material is injected and filled from the opening in the upper part of the case 11 and cured to be insulated and sealed.

  When the ignition coil 1 is operated, a primary current is input from the primary voltage input unit 12, the primary coil 15 is energized, and the magnetic energy generated in the primary coil 15 is generated by the central iron core 18 and the outer iron core. 19, a high voltage corresponding to the turn ratio of the primary coil 15 and the secondary coil 17 is generated in the secondary coil 17. The generated high voltage is sent from the secondary coil 17 through the secondary high voltage terminal 22 through the spring 23 to a spark plug (not shown) connected to the spring 23.

In the previous embodiment, the space B is provided in the lower part of the case-side outer peripheral surface where the primary voltage input part of the case is fitted, and the space B is provided in the lower part. A wide frame may be provided also on the side surface of the primary voltage input unit. As a result, the insulating casting material that leaks out the insulating casting material by sewing the gap in the fitting groove with the primary voltage input section guides the resin when drooping downstairs to the space of the lower frame that is widely provided. It plays a role as a groove space and can suppress resin sagging to other parts as much as possible.

It is a perspective view showing the appearance of the cylindrical ignition coil for internal-combustion engines to which the technology of the present invention is applied. It is a longitudinal cross-sectional view of FIG. It is sectional drawing of the high voltage | pressure tower part of FIG. It is a perspective view showing the external appearance of the cylindrical ignition coil for internal combustion engines to which the prior art is applied. It is a longitudinal cross-sectional view of FIG. It is a figure showing the assembly | attachment direction of the primary bobbin and case of the cylindrical ignition coil for internal combustion engines to which the prior art is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 11 Case 11b Upper storage part 11d Depression 11f Rib 11h Umbrella part 12 Primary voltage input part 12w Frame 13 Igniter 14 Primary bobbin 14a High voltage tower part 14t Primary bobbin engagement protrusion 15 Primary coil 16 Secondary bobbin 17 Secondary coil 18 Central iron core 19 Exterior iron core 21 Permanent magnet 22 Secondary high voltage terminal 23 Spring 25 Plug boot 26 Rain cover 27 Air vent hole 41 O-ring A Protrusion B Space C Toroidal recess 100 Ignition coil 110 Primary coil Assembly 111 Case 111b Upper housing part 111d Hole 112 Primary voltage input part 113 Igniter 114 Primary bobbin 114a High-voltage tower part 114t Primary bobbin engagement protrusion 114u Outer peripheral surface 115 Primary coil 116 Secondary bobbin 117 Secondary coil 118 Center Iron core 119 Exterior iron core 121 Permanent magnet 122 secondary high-voltage terminal 123 spring 125 plug boot 126 rain cover 127 vent 141 O-ring

Claims (6)

  A central iron core, a primary coil in which a primary winding is wound around a primary bobbin disposed coaxially with the central iron core, and a secondary coil in which a secondary winding is wound around a secondary bobbin; An igniter that controls on / off of a primary current that flows through the primary coil of the ignition coil, a primary current input unit that supplies the primary current to the igniter, and a cylindrical case that houses the primary coil and the secondary coil; The primary bobbin is formed from the outer periphery of a high-pressure tower portion that supplies a high voltage generated by the secondary coil to the spark plug, and the high-pressure tower portion is accommodated in the cylindrical case and protrudes. In the internal combustion engine ignition coil, a frame is provided on an outer peripheral surface of a portion where the primary voltage input portion is fitted to the cylindrical case, and the frame is formed from a surface where the primary voltage input portion is fitted to the cylindrical case. The lower part is wide and large Cylindrical ignition coil for an internal combustion engine according to claim.   A central iron core, a primary coil in which a primary winding is wound around a primary bobbin disposed coaxially with the central iron core, and a secondary coil in which a secondary winding is wound around a secondary bobbin; An igniter that controls on / off of a primary current that flows through the primary coil of the ignition coil, a primary current input unit that supplies the primary current to the igniter, and a cylindrical case that houses the primary coil and the secondary coil; The primary bobbin is formed from the outer periphery of a high-pressure tower portion that supplies a high voltage generated by the secondary coil to the spark plug, and the high-pressure tower portion is accommodated in the cylindrical case and protrudes. In the ignition coil for an internal combustion engine, the lower end of the case has an outer diameter end projecting in the axial direction toward the high-pressure tower side, and the outer periphery of the cylinder of the case located in front of the outer diameter end in the axial direction is Annulus smaller than the outer diameter of the cylinder The cylindrical part for an internal combustion engine according to claim 1 or 2, wherein a concave part is formed in a circumferential direction, and the annular concave part is formed with a rib protruding at equal intervals with respect to the outer peripheral direction of the case. Ignition coil.   A central iron core, a primary coil in which a primary winding is wound around a primary bobbin disposed coaxially with the central iron core, and a secondary coil in which a secondary winding is wound around a secondary bobbin; An igniter that controls on / off of a primary current that flows through the primary coil of the ignition coil, a primary current input unit that supplies the primary current to the igniter, and a cylindrical case that houses the primary coil and the secondary coil; The primary bobbin is formed from the outer periphery of a high-pressure tower portion that supplies a high voltage generated by the secondary coil to the spark plug, and the high-pressure tower portion is accommodated in the cylindrical case and protrudes. In the internal combustion engine ignition coil, a convex portion is provided in a part of the outer circumferential direction of the umbrella portion below the upper storage portion of the case so as to protrude toward the upper storage portion, and the plug hole of the engine and the ignition coil Before sealing The rain cover that is in close contact with the umbrella portion is also provided with a convex portion so as to protrude in the direction of the upper storage portion so as to match this, and an air vent hole communicating with the plug hole is provided in the convex portion of the rain cover. A cylindrical ignition coil for an internal combustion engine according to any one of claims 1 to 3.   A central iron core, a primary coil in which a primary winding is wound around a primary bobbin disposed coaxially with the central iron core, and a secondary coil in which a secondary winding is wound around a secondary bobbin; An igniter that controls on / off of a primary current that flows through the primary coil of the ignition coil, a primary current input unit that supplies the primary current to the igniter, and a cylindrical case that houses the primary coil and the secondary coil; The primary bobbin is formed from the outer periphery of a high-pressure tower portion that supplies a high voltage generated by the secondary coil to the spark plug, and the high-pressure tower portion is accommodated in the cylindrical case and protrudes. In an internal combustion engine ignition coil, the plug boot fitted with the spark plug has a smaller outer diameter on the side fitted with the case, the outer diameter of the lower end of the case is the same as the inner diameter, and the case and the plug boot are assembled. When the plastic An internal combustion engine for cylindrical ignition coil of claim 1 to claim 3, characterized in that allowed submerge boots some upper inner diameter side of the case bottom.   5. The cylindrical ignition coil for an internal combustion engine according to claim 1, comprising: an upper storage portion having a large opening of the case for storing the igniter.   A cylindrical ignition coil for an internal combustion engine, wherein at least two or more of claims 1 to 5 are combined.

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