JP2012186299A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for an internal combustion engine which secures high waterproofness, reduces the height of the coil, and minimizes the weight increase caused by adding a chamber part.SOLUTION: A high voltage generation part 3 generating high voltage is housed in a coil case 4. A plug hole seal 5 is provided so as to close an opening of a plug hole 2 to which an ignition plug is attached. An ignition coil for an internal combustion engine includes: an air chamber part 6 provided at an outer side part of the high voltage generation part 3; and a ventilation part 9 which is located at the lateral side of the high voltage generation part 3 and is used for ventilation between the air chamber part 6 and the plug hole 2. An opening 10, which is formed at an upper part of the air chamber part 6 and has a cross section area smaller than a cross section area of the air chamber part, is sealed by a sealing member 7.

Description

  The present invention relates to an ignition coil for an internal combustion engine that supplies a high voltage to generate a spark discharge in an ignition plug of the internal combustion engine, and more particularly to an ignition coil for an internal combustion engine that is suitable for waterproofing a plug hole.

  Conventionally, an ignition coil for an internal combustion engine connects outside air and a plug hole in order to reduce an increase in pressure in the plug hole that occurs during assembly to the engine or to prevent an increase in ozone gas concentration caused by a high voltage. An air passage is provided so that the plug hole can be ventilated by outside air. However, when the engine temperature changes from high temperature to low temperature or from normal temperature to low temperature, the air in the plug hole is cooled, and as a result, the volume of the plug hole contracts and negative pressure is generated inside the plug hole. If the fire coil is flooded at this time, water may enter the plug hole from the air passage.

  In view of this, there is conventionally known one having a water retention chamber that can retain water between the coil case and the plug hole seal (see, for example, Patent Document 1).

JP 2000-291523 A

  However, in the ignition coil described in Patent Document 1, in order to ensure high waterproofness, it is necessary to increase the volume of the water retention chamber part for storing water. However, if the volume of the water retention chamber part is increased, the ignition coil This will lead to a larger size and a higher profile, and will be against the current needs for ignition coils, which are smaller and lower profile. For this reason, in the configuration described in Patent Document 1, there is a limit to the volume of the water retention chamber that can be formed in the air passage, and when it is mounted on a DOHC engine or the like having poor drainage around the ignition coil, water into the plug hole There was a problem that intrusion could not be prevented.

  An object of the present invention is to provide an ignition coil for an internal combustion engine that can ensure high waterproofness, reduce the height of the coil, and minimize the increase in weight due to the addition of the chamber portion. It is in.

(1) In order to achieve the above object, the present invention closes a high voltage generator that generates a high voltage, a coil case that houses the high voltage generator, and an opening of a plug hole to which a spark plug is attached. An independent ignition type ignition coil that is directly connected to an ignition plug of an internal combustion engine, and is provided in an outer portion of the high voltage generator , A vent portion disposed on the side of the high voltage generating portion, for venting the air chamber portion and the plug hole, and formed on an upper portion of the air chamber portion, and the air chamber portion An opening having a smaller cross-sectional area than the above-described cross-sectional area and a seal member for sealing the opening are provided.
With this configuration, high waterproofness can be secured, the coil can be reduced in height, and weight increase due to the addition of the chamber portion can be minimized.

  (2) In the above (1), preferably, the sealing member is fixed by press-fitting, adhesion or welding.

  (3) In the above (1), preferably, the opening and the seal member are circular.

  (4) In the above (1), preferably, an insulating resin is cast above the seal member.

  (5) In the above (1), preferably, the inside above the opening is tapered.

  (6) In the above (1), preferably, the seal member is made of the same material as the coil case.

  (7) In the above (1), preferably, the sealing member has a concave cross section.

  (8) In the above (1), preferably, it is provided with a water-preventing wall provided in the air chamber and in the vicinity of the inlet of the ventilation portion.

  According to the present invention, high waterproofness can be ensured, the coil can be reduced in height, and the weight increase due to the addition of the chamber portion can be minimized.

It is sectional drawing which shows the structure of the ignition coil for internal combustion engines by the 1st Embodiment of this invention. It is sectional drawing of another cross-sectional position which shows the structure of the ignition coil for internal combustion engines by the 1st Embodiment of this invention. It is a top view which shows the structure of the ignition coil for internal combustion engines by the 1st Embodiment of this invention. It is a bottom view which shows the structure of the ignition coil for internal combustion engines by the 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the ignition coil for internal combustion engines by the 2nd Embodiment of this invention.

Initially, the structure of the ignition coil for internal combustion engines by the 1st Embodiment of this invention is demonstrated using FIGS. 1-3.
FIG. 1 is a cross-sectional view showing a configuration of an ignition coil for an internal combustion engine according to a first embodiment of the present invention. FIG. 2 is a plan view of another cross-sectional position showing the configuration of the internal combustion engine ignition coil according to the first embodiment of the present invention. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a plan view showing the configuration of the ignition coil for an internal combustion engine according to the first embodiment of the present invention.

  In FIG. 1, an internal combustion engine ignition coil 1 is an independent ignition type internal combustion engine ignition coil that is mounted in a plug hole 2 of each cylinder formed in a cylinder head of an internal combustion engine and is directly connected to an ignition plug 21 for use. is there. The internal combustion engine ignition coil 1 includes a connector 16. Electric power is supplied from an external battery to the igniter 17 and the coil portion inside the internal combustion engine ignition coil 1 via the internal terminal of the connector 16, and the internal combustion engine ignition coil is supplied from an external engine control unit (ECU). An ignition signal is supplied to the igniter 17 in the interior of 1.

  The ignition coil 1 includes an igniter 17 that switches in accordance with an ignition signal from the ECU, a high voltage generator 3, a coil case 4, and a plug hole seal 5. The high voltage generating unit 3 includes a primary coil, a secondary coil, a laminated iron core, and the like, and a coil unit that generates a high voltage. The coil case 4 accommodates the high voltage generator 3 and the igniter 17 and is made of a thermoplastic resin. The plug hole seal 5 is provided between the coil case 4 and the plug hole 2 in order to close the opening of the plug hole 2.

  The plug hole 2 is formed for each cylinder in the cylinder head CH of the internal combustion engine. A spark plug 21 is attached to the cylinder head by screwing under the plug hole 2.

  The lower part of the coil case 4 is sealed with a metal terminal portion 19. Inside the coil case 4, the high voltage generator 3 is inserted. The pin 18 is fixed to the secondary bobbin of the coil part of the high voltage generating part 3, and is connected to the secondary coil. The pin 18 is made of, for example, phosphor bronze and has a spring property. In a state where the high voltage generator 3 is inserted into the coil case 4, the end of the pin 18 is in contact with the terminal portion 19 and is conductive due to the spring property of the pin 18. An insulating resin 8 such as an epoxy resin is injected into the coil case 4 to seal the igniter 17 and the high voltage generator 3.

  A plug hole seal 5 is attached to the lower part of the coil case 4. The plug hole seal 5 is made of silicon rubber or the like. The plug hole seal 5 extends in a cylindrical shape in the downward direction in the figure, and is inserted into the electrode terminal at the top of the spark plug. A metal spring 20 is inserted into the cylindrical space of the plug hole seal 5 to electrically connect the terminal portion 19 and the electrode terminal on the upper portion of the spark plug 21, and is generated in the high voltage generating portion 3. The high voltage pulse thus supplied is supplied to the spark plug 21.

  As shown in FIG. 2, a mounting portion 4 TB is integrally formed on the side portion of the coil case 4. On the other hand, a mounting seat ZA is formed integrally with the cylinder head CH on the cylinder head CH. The mounting portion 4TB is fixed to the mounting seat ZA with a bolt BT or the like, and the ignition coil 1 is fixed to the upper portion of the cylinder head CH.

  An air chamber portion 6 and a ventilation portion 9 are integrally formed on an outer side portion of the coil case 4 in the illustrated right direction (a side portion of the high voltage generating portion 3). The air chamber portion 6 and the ventilation portion 9 communicate with each other at their upper portions. The air chamber 6 has a “bottom opening” on the lower surface where the cup is turned upside down. The plug hole seal 5 is formed with a small through hole 5HO. Further, a groove portion 4GR is formed on the outer surface of the coil case 4. When the plug hole seal 5 is attached to the lower part of the coil case 4, the upper part of the groove part 4 GR communicates with the ventilation part 9, and the lower part of the groove part 4 GR communicates with the through hole 5 HO of the plug hole seal 5. The groove portion 4GR is, for example, a minute one having a width of 0.8 mm and a depth of about 0.4 mm. However, even when the plug hole seal 5 is attached to the lower portion of the coil case 4, the groove portion 4GR maintains the groove state. Thus, the ventilation portion 9 and the through hole 4HO can communicate with each other. When the ignition coil 1 is fixed to the upper part of the cylinder head CH, the through hole 5HO communicates with the plug hole 2.

  Therefore, the air flow path between the plug hole 2 and the outside air is in the order of the air chamber portion 6, the vent portion 9, the groove portion 4 GR, the through hole 5 HO, and the plug hole 2.

  When the ignition coil 1 is attached to a DOHC engine or the like having poor drainage around the ignition coil 1, if the ignition coil 1 gets wet, the cylinder head CH is cooled, and the temperature of the plug hole 2 is lowered. The air in the plug hole is cooled and the volume shrinks, and a negative pressure is generated in the plug hole. The negative pressure causes water to enter the plug hole, but by arranging the position of the air chamber 6 on the side of the high voltage generator 3, the ignition coil 1 can be reduced in height and the air can be reduced. Since the restriction in the height direction of the chamber portion 6 is reduced, the volume of the air chamber 6 can be increased, so that it is possible to cope with a larger environmental change (temperature change).

  Here, even if the water level in the air chamber part 6 rises by making the volume of the air chamber part 6 larger than the volume shrinkage due to the temperature change in the plug hole, the ventilation part continues in the plug hole. Since it does not go up to the inlet 9 (upper part of the ventilation part 9), water does not enter the plug hole. The volume of the air chamber 6 is 4 cc, for example. On the other hand, since the volume of the plug hole 2 is about 40 cc, and the volume shrinkage due to temperature change in the plug hole in this case is about 2 cc, the volume of the air chamber 6 is larger than the volume shrinkage (2 cc). It has become.

  By setting the volume in the air chamber 6 to 3 cc or more when horizontally mounted, a volume equal to or larger than the volume contraction due to the temperature change in the plug hole can be secured, so that water does not reach the vent inlet 11. , Water can be prevented from entering the plug hole.

  In addition, since the lower surface of the air chamber portion 6 is “entirely open”, when the water level around the ignition coil 1 becomes lower than the lower surface of the air chamber portion 6, the negative pressure in the plug hole is placed in the air chamber portion 6. Since the water sucked up into the air chamber 6 by the pressure is discharged instantly, the drainage is improved. Therefore, water intrusion into the plug hole can be suppressed even under environmental conditions in which the ignition coil 1 temporarily repeats a complete submerged state.

  An opening 10 is provided above the air chamber 6 and the vent 9. The sectional area of the opening 10 is smaller than the sectional area of the air chamber 6. At the upper part of the air chamber part 6, a ventilation part inlet 11 consisting of a small opening communicating with the opening part 10 is formed. The opening 10 is sealed with a seal member 7. As a result, the air chamber 6 and the vent 9 are communicated with each other, and the vent 9 is communicated with the outside air via the air chamber 6. The seal member 7 is fixed by press-fitting, adhesion, or welding.

  Here, the cross-sectional area of the opening 10 and the cross-sectional area of the air chamber 6 will be described with reference to FIG. In FIG. 3, a shape A <b> 1 indicated by a one-dot chain line indicates a cross-sectional shape of the air chamber portion 6, which is a shape obtained by subtracting a semicircular shape of the ventilation portion 9 from a substantially rectangular shape. Let the cross-sectional area be A1. On the other hand, the circle indicated by the broken line indicates the cross-sectional shape of the opening 10, and the cross-sectional area is A2. In the present embodiment, the cross-sectional area A2 of the opening 10 is smaller than the cross-sectional area A1 of the air chamber 6.

  By making the opening 10 small, the seal member 7 that seals the opening 10 can be miniaturized, so that an increase in weight due to the use of the seal member 7 can be minimized.

  Further, since the shape of the opening 10 at the upper part of the air chamber 6 is made circular, the seal member 7 can also be made circular. Therefore, when the seal member 7 is assembled, circumferential positioning is not necessary. The process can be simplified. Then, by making the guide portion 15 of the coil case 4 above the opening portion 10 into a tapered shape, when the seal member 7 is freely dropped from the assembly equipment above the coil case 4, the opening portion 10 of the coil case 4 The positional deviation of the seal member 7 can be suppressed, and variations in positional accuracy can be reduced.

  In addition, by casting an insulating resin 8 for insulating the high voltage generator 3 above the seal member 7, the weight increase of the insulating resin 8 can be limited to the range of the seal member 7. Therefore, an increase in the weight of the insulating resin 8 is minimized.

  Moreover, by making the coil case 4 and the seal member 7 the same material, it is possible to make both parts common.

  Further, the seal member 7 is formed in a concave shape, and there is no strength member other than the seal portion of the seal member 7 inside the opening portion 10, and the stress generated in the seal member 7 can be reduced when press-fitted. it can.

  In addition, when the volume in the air chamber 6 is set to 3 cc or more when mounted horizontally, a volume equal to or larger than the volume contraction due to the temperature change in the plug hole can be secured, so that water can reach the vent portion inlet 11. Therefore, water can be prevented from entering the plug hole.

  The present invention can be applied not only to a type in which a coil portion is disposed in a plug hole of an internal combustion engine, but also to a type of ignition coil in which a coil portion is disposed above a plug hole.

  As described above, in the present embodiment, the air chamber portion is disposed on the side of the coil case, and the volume of the air chamber is made larger than the volume contraction due to the temperature change in the plug hole, thereby improving the water toughness. I am letting. Moreover, the cross-sectional area of an opening part can be made smaller than the cross-sectional area of an air chamber part, the size of the sealing member of the upper part of an air chamber part can be reduced, and an increase in weight can be suppressed.

  As described above, according to the present embodiment, even when mounted on a DOHC engine or the like having poor drainage around the ignition coil, it is possible to ensure a high waterproof property that suppresses water intrusion into the plug hole. The height can be reduced, and the increase in weight due to the addition of the chamber portion can be minimized.

Next, the configuration of the ignition coil for an internal combustion engine according to the second embodiment of the present invention will be described with reference to FIGS.
FIG. 4 is a bottom view showing the configuration of the internal combustion engine ignition coil according to the second embodiment of the present invention. FIG. 5 is a cross-sectional view showing a configuration of an internal combustion engine ignition coil according to a second embodiment of the present invention. 1 and 2 indicate the same parts.

  In the present embodiment, as shown in FIG. 4, by providing a plurality of walls 12 formed by the coil case 4 in the vicinity of the vent inlet 11 in the air chamber 6, the vicinity of the vent inlet 11 is covered with water. Suppress.

  In addition, as shown in FIG. 5, the wall 12 is straight and vertically extended, and the bottom surface of the wall 12 is basically horizontal, but a slit is provided to prevent water droplets from collecting, or an inverted triangular shape. A shape may be used.

  Also according to this embodiment, even when mounted on a DOHC engine or the like with poor drainage around the ignition coil, it ensures high waterproofness that suppresses water intrusion into the plug hole, and further reduces the coil height, In addition, an increase in weight due to the addition of the chamber portion can be minimized.

DESCRIPTION OF SYMBOLS 1 ... Ignition coil 2 for internal combustion engines ... Plug hole 3 ... High voltage generation part 4 ... Coil case 5 ... Plug hole seal 6 ... Air chamber part 7 ... Sealing member 8 ... Insulating resin 9 ... Ventilation part 10 ... Opening part 11 ... Vent inlet 12 ... Water-preventing wall 15 ... Guide 16 ... Connector 17 ... Ignator 18 ... Pin 19 ... Terminal 20 ... Spring 21 ... Ignition plug

Claims (8)

A high voltage generator for generating a high voltage;
A coil case that houses the high voltage generator;
A plug hole seal provided to close the opening of the plug hole to which the spark plug is attached;
An independent ignition type ignition coil used directly connected to an ignition plug of an internal combustion engine,
An air chamber portion provided on an outer side of the high voltage generation unit;
A ventilation part disposed on the side of the high voltage generation part, for venting the air chamber part and the plug hole;
An opening having a cross-sectional area that is smaller than the cross-sectional area of the air chamber part, and formed on the air chamber part;
An ignition coil for an internal combustion engine, comprising: a seal member that seals the opening. The ignition coil for an internal combustion engine according to claim 1,
The ignition coil for an internal combustion engine, wherein the seal member is fixed by press-fitting, adhesion or welding. The ignition coil for an internal combustion engine according to claim 1,
The ignition coil for an internal combustion engine, wherein the opening and the seal member are circular. The ignition coil for an internal combustion engine according to claim 1,
An ignition coil for an internal combustion engine, wherein an insulating resin is cast above the seal member. The ignition coil for an internal combustion engine according to claim 1,
An ignition coil for an internal combustion engine, wherein an inner side above the opening is tapered. The ignition coil for an internal combustion engine according to claim 1,
The ignition coil for an internal combustion engine, wherein the seal member is made of the same material as the coil case. The ignition coil for an internal combustion engine according to claim 1,
An ignition coil for an internal combustion engine, wherein the seal member has a concave cross section. The ignition coil for an internal combustion engine according to claim 1,
An ignition coil for an internal combustion engine, comprising a water-preventing wall provided in the air chamber and in the vicinity of an inlet of the ventilation portion.

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