JP2015002303A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for internal combustion engine, including an air chamber for preventing such a phenomenon that the water enters a plug hole, and ensuring excellent production efficiency and cost without requiring a complicated metal mold.SOLUTION: An air chamber 20 having an opening on the plug hole side is formed on the side face of a case 60, and the air chamber 20 is provided with a ventilation part 10 molded separately from the case 60. A vent hole 12 connecting the inside of the plug hole and the inside of the air chamber 20 via the boundary surface of a protector 70 and the case 60 is formed in the ventilation part 10, and the ventilation part 10 is inserted from the opening side of the air chamber 20, and fixed in place. A cavity 26 penetrating the case 60 and air chamber 20 is provided in a boundary wall of the case, and a case side wall 16 for closing the cavity 26, when the air chamber 20 is mounted, is formed in the ventilation part 10.

Description

The present invention relates to an ignition coil for supplying a high voltage to an ignition plug provided in an internal combustion engine, and more particularly to an ignition coil for an internal combustion engine having a function of waterproofing a plug hole.

Conventionally, when an ignition coil for an internal combustion engine is attached to the upper part of the engine, a protector provided in the case of the ignition coil is used to securely connect the ignition plug provided in the plug hole with the upper end of the plug hole. Is sealed. In such an ignition coil, the internal pressure in the plug hole changes due to the temperature change of the engine, and when the ignition coil gets wet, the air in the plug hole is cooled and the volume is contracted, resulting in a negative pressure state. May penetrate. In order to solve this problem, it is known to form a water retention chamber in the ignition coil. For example, JP 2012-186299 A (hereinafter “Patent Document 1”) has been proposed.

FIG. 5 is a cross-sectional view showing the configuration of the ignition coil for an internal combustion engine disclosed in Patent Document 1. In the ignition coil for an internal combustion engine disclosed in Patent Document 1, an air chamber portion 20 and a ventilation portion 10 are integrally formed on the outer side portion of the coil case 60 in the illustrated left direction. Further, the air chamber portion 20 and the ventilation portion 10 communicate with each other at their upper portions. Further, the air chamber portion 20 has a “lower surface” that is a lower surface in which a cup is turned upside down.

Further, by keeping the volume of the air chamber portion 20 larger than the volume shrinkage due to the temperature change in the plug hole 90, even if the water level in the air chamber portion 20 rises, continuous air flow in the plug hole 90 Since it does not go up to the inlet of the part 10 (upper part of the ventilation part 10), water does not enter the plug hole 90. Accordingly, the volume of the air chamber 20 is set to 4 cc, for example. On the other hand, the volume of the plug hole 90 is about 40 cc, and the volume shrinkage due to the temperature change in the plug hole 90 in this case is about 2 cc. Therefore, the volume of the air chamber 20 is larger than the volume shrinkage (2 cc). It is getting bigger.

In addition, an opening 210 is provided above the air chamber 20 and the vent 10. The sectional area of the opening 210 is smaller than the sectional area of the air chamber 20. At the upper part of the air chamber part 210, a ventilation part inlet 220 comprising a small opening communicating with the opening part 210 is formed. The opening 210 is sealed by a seal member 230. As a result, the air chamber 20 and the ventilation part 10 communicate with each other, and the ventilation part 10 communicates with the outside air via the air chamber part 20. It is described that the seal member 230 is fixed by press-fitting, adhesion, or welding.

As another example, Japanese Patent Application Laid-Open No. 2012-186411 (hereinafter “Patent Document 2”) has been proposed.

FIG. 6 shows a perspective view of the case before the cover is attached to the ignition coil of Patent Document 2 and the cover. In the ignition coil for an internal combustion engine of Patent Document 2, the column portion forming side wall portion 24 provided with the column portion 10 is located on the inner peripheral side with respect to the outer peripheral position of the seal rubber 70, and the column portion 10 is formed with the column portion. It is formed upward from a base portion 310 formed on the outer peripheral side of the side wall portion 24 and at an upper position with respect to the seal rubber 70. Further, the column part 10 is formed as a substantially semicircular cylindrical part as a part protruding toward the radial direction of the ignition coil 100 on the outer side surface 330 of the side wall part 320 of the case part 60. Further, the column portion forming side wall portion 24 is formed as a planar side wall portion in which a part of the circumferential direction located above the annular seal rubber 70 is recessed inward from the outer peripheral contour of the seal rubber 70. Yes.

In addition, the base portion 310 is formed as a portion located on the inner peripheral side of the outer peripheral contour of the seal rubber 70 and on the outer peripheral side of the columnar portion forming side wall portion 24. Furthermore, the base portion 310 is provided with a protruding portion 340 that protrudes laterally with the plate surface directed in the vertical direction.

Further, the cover 350 is attached to the notch 360 in the case 60 with the lower end forming the opening portion disposed around the protrusion 340. Further, the notch 360 is provided in the side wall part 320 of the case part 60 at both side positions with respect to the column part 10 by being cut out parallel to each other downward from the side wall upper end part 370, and the notch part 360 is a slit that is long in the vertical direction. The side walls 320 are formed in parallel to each other.

JP 2012-186299 A JP 2012-186411 A

However, the conventional ignition coil for internal combustion engine has the following problems. That is, in patent document 1, since the air chamber part and the ventilation | gas_flowing part are integrally formed in the outer part of a coil case, the problem that a case shaping | molding metal will become a complicated shape arises. Further, in order to form the ventilation portion with a mold, a process of providing an opening and extracting the mold in the direction of the opening is required, and thus a seal member for sealing the opening is necessary. From FIG. 5, the weight of the resin on the seal member blocks the air inlet for communicating the air chamber and the air vent, and the connection between the air chamber and the air vent due to individual differences in the seal member and mounting errors. The problem that quality cannot be maintained arises.

In Patent Document 2, since the cover is attached to two notches in the case portion with the cover facing downward, a dimensional error is likely to occur between the cover and the notch portion, or when the cover is attached to the case. When the case or the cover is deformed, there is a problem that the cover is prevented from being attached to the notch. Furthermore, because the capacity of the plug hole and the type of ignition coil to be attached differ depending on the engine model, it is necessary to form a cover that is suitable for the capacity of the plug hole and the shape of the case, which causes problems in production efficiency and cost. .

The present invention has been made in view of the above problems, and when the density in the plug hole changes due to a change in engine temperature and the ignition coil is submerged, the plug hole is cooled and the volume is contracted. An ignition coil provided with an air chamber that prevents the phenomenon of water intrusion into a hall does not require a complicated mold, and an object is to provide an ignition coil for an internal combustion engine that is excellent in production efficiency and cost.

In order to solve the above problems, the present invention is configured as follows. That is, an internal combustion engine that includes a coil portion including a primary coil, a secondary coil, and an iron core, a case that accommodates the coil portion, and a protector that is attached to the case to seal the plug hole. In the engine ignition coil, an air chamber having an opening on the plug hole side is formed on the side surface of the case, and the air chamber includes a ventilation portion formed separately from the case. A vent hole is formed in the portion for connecting the plug hole and the air chamber through a boundary surface between the protector and the case, and the vent portion is inserted and fixed from the opening side of the air chamber. An ignition coil for an internal combustion engine characterized by the above.

In the above configuration, the ventilation portion may be fixed to a case boundary wall between the case and the air chamber by fitting or bonding, and the case boundary wall may include the inside of the case and the air chamber. A gap portion penetrating the inside may be provided, and a side portion of the case that closes the gap portion may be formed in the ventilation portion when the ventilation portion is attached to the air chamber. The vent may be arranged with the vent opening opened on the air chamber side in the vicinity of a surface facing the opening of the air chamber. Further, the vent may be configured such that the vent opening opened to the plug hole side is disposed between the protector and the case.

As described above, a coil portion including a primary coil, a secondary coil, and an iron core, a case that accommodates the coil portion, and a protector that is attached to the case for sealing the plug hole. In the ignition coil for an internal combustion engine, an air chamber having an opening on the plug hole side is formed on the side surface of the case, and the air chamber includes a ventilation portion formed separately from the case. The ventilation portion is formed with a vent hole that connects the inside of the plug hole and the air chamber via a boundary surface between the protector and the case, and the ventilation portion is inserted from the opening side of the air chamber. By fixing, an ignition coil for an internal combustion engine having a function of waterproofing the plug hole with excellent production efficiency and cost without requiring a complicated mold is realized. It can be. In addition, since the ventilation part and the case are attached at one place, a dimensional error is likely to occur between the ventilation part and the case, or the case or the ventilation part is deformed when the ventilation part is attached to the case. It is possible to prevent a problem that the mounting between the air vent and the ventilation portion is hindered.

Further, the ventilation portion is inserted from the opening side of the air chamber and fixed to the case boundary wall between the case and the air chamber by fitting or bonding, and the case boundary wall includes A gap portion penetrating through the air chamber, and a case side portion that closes the gap portion when the air chamber is attached to the air chamber, thereby forming a bottom surface and a case boundary on the plug hole side of the case The side surface as the wall side is surely sealed by the ventilation portion, and it is possible to prevent a defect that the mold resin for performing electrical connection and physical curing of the coil portion leaks out of the case.

It is a figure explaining the ignition coil for internal combustion engines which is a 1st Example of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a state before assembly of an ignition coil for an internal combustion engine according to a first embodiment. FIG. 3 is a perspective view showing an assembled internal combustion engine ignition coil according to a first embodiment. FIG. 4 is a BB cross-sectional view of the internal combustion engine ignition coil of FIG. 3 as viewed from the A direction. Sectional drawing which shows the structure of the ignition coil for internal combustion engines of patent document 1 is shown. The perspective view which shows the case part before attaching a cover concerning the ignition coil of patent document 2, and a cover is shown.

An example showing the embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a view for explaining an ignition coil for an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is a perspective view showing the state before the ignition coil for the internal combustion engine is assembled, and FIG. FIG. 3 is a perspective view showing the same, and FIG. 4 is a sectional view taken along line BB of the ignition coil for the internal combustion engine shown in FIG.

1A is a perspective view of an ignition coil for an internal combustion engine, FIG. 1B is a top view of the ignition coil shown in FIG. 1A viewed from the direction of arrow A, and FIG. The bottom view which looked at the ignition coil shown in FIG. In addition, the ignition coil 100 includes an iron core having a closed magnetic circuit structure formed by combining a central iron core 50 and an outer iron core 52 formed of a silicon steel plate, a primary coil 30 on the outer circumference of the central iron core 50, and the primary coil. The coil part which consists of the secondary coil 40 in the outer periphery of the coil 30 is accommodated in the case 60 shape | molded with insulating resin, and is comprised. Further, on the side surface of the case 60, a connector 66 for supplying a power supply voltage and an ignition signal from an external battery or ECU to the coil portion, and a flange for attaching and fixing the ignition coil 100 to the engine head 64 is formed.

Further, a high voltage tower 62 for supplying a high voltage boosted by the coil portion to a spark plug 76 is formed in a plug hole 90 formed in an upper part of the engine, which will be described later, on the bottom surface of the case 60. Further, an air chamber 20 having an opening 22 in the direction of the high-pressure tower 62 is formed on the side surface of the case 60.

Further, on the boundary wall 24 side of the air chamber 20 with the case 60, there is provided a ventilation part 10 having a cylindrical ventilation hole 12 formed in PBT (polybutylene terephthalate). Further, the vent 10 is arranged in a direction in which the vent 12 connects the opening 22 of the air chamber 20 from the opening 68 of the case 60.

Further, the vent portion 10 is formed with a fitting portion (vent portion side) 14, and the fitting portion (vent portion side) 14 is connected by a fitting portion (case side) 28 formed on the case boundary wall 24. It is fixed. Further, the case 60 is filled with a mold resin 80 to achieve electrical insulation and physical fixation of the coil portion.

2 and 3, the high-pressure tower 62 is provided with a protector 70 for connecting the spark plug 76. The protector 70 is formed of an elastic member and has a cylindrical inner peripheral portion 72. Further, the vent 10 is formed in an L shape, and the vent 12 is also formed in an L shape having a vent 12a on the air chamber 20 side and a vent 12b on the protector 70 side.

Further, the ventilation portion 10 is formed with a case side wall 16 that becomes a part of a side surface of the case 60 after being attached to the air chamber 20. Further, a gap 26 is formed in the case boundary wall 24 and penetrates the air chamber 20 and the case 60.

2, the assembling procedure of the ventilation portion 10, the case 60, and the protector 70 will be described. The ventilation portion 10 has directions x, y, and z, and arrows x, y, and z of the case 60. In addition to matching the directions, the vent portion 10 is slid and attached from the direction of the arrow 1 by aligning the vent portion side fitting portion 14 and the case side fitting portion 28. Further, after the ventilation portion 10 is attached to the case 60, the protector 70 is attached to the high-pressure tower 62 from the direction of arrow 2.

By the above assembly procedure, the gap portion 26 formed in the case boundary wall 24 is sealed by the case side wall 16 of the ventilation portion 10 by attaching the ventilation portion 10, and the inside of the case 60 and the air The chamber 20 is configured as a separate space. Accordingly, the mold resin 80 does not flow into the air chamber 20 when the mold resin 80 is filled in the case 60.

In FIG. 4, one of the protectors 70 is fitted and fixed to the high-pressure tower 62, and the other has a part of the spark plug 76 inserted into the inner peripheral portion 72. The protector 70 is provided with a spring 74 for electrically connecting the high-pressure tower 62 and the spark plug 76. Further, the protector 70 closes the plug hole 90 by closing the opening of the plug hole 90.

Further, the air chamber 20 and the plug hole 90 are ventilated, and the path of ventilation is the opening 22 of the air chamber 20 → the air chamber 20 → the air chamber side vent 12a → the vent 12 → The protector side vent 12b → the boundary surface of the case 60 and the protector inner peripheral portion 72 → the protector inner peripheral portion 72 → the plug hole 90. Accordingly, when the temperature of the engine becomes high and the air in the plug hole 90 that is sealed with the protector 70 expands, the expanded air becomes the plug hole 90 → the protector inner peripheral portion 72 → the case 60. And the boundary surface of the protector inner peripheral part 72 → the protector side vent 12b → the vent 12 → the air chamber side vent 12a → the air chamber 20 → the air chamber 20 is released through the path 22 of the air chamber 20. The

In addition, when a sudden temperature drop occurs such as the engine getting wet, the air in the plug hole 90 sealed by the protector 70 contracts and the plug hole 90 is in a negative pressure state. In order to eliminate the negative pressure, the air in the air chamber 20 is changed from the air chamber 20 → the air chamber side vent 12a → the vent 12 → the protector side vent 12b → the case 60 and the inner circumference of the protector. Injection is performed in the path of the boundary surface of the portion 72 → the protector inner peripheral portion 72 → the plug hole 90. At this time, even if the water reaches the vicinity of the ignition coil 100, the opening 22 of the air chamber 20 is provided in the direction of the high-pressure tower 62 (vertically downward), so that water enters the air chamber 20. There is nothing.

The capacity of the air chamber 20 is designed to be larger than the amount when the air in the plug hole 90 contracts most due to the temperature change of the engine, and the height of the air chamber side vent 12a is set to the height of the air chamber It is configured to be disposed at a height that prevents water that has entered 20 from reaching the air chamber side vent 12a.

With the above configuration, by forming the air chamber 20 having the opening 22 in the direction of the high-pressure tower 62 on the side surface of the case 60, the capacity of the plug hole or the ignition coil 100 to be attached depending on the model of the engine. Even if the types are different, an ignition coil having the air chamber 20 adapted to the capacity in the plug hole 90 and the shape of the case 60 can be realized.

In addition, the case boundary wall 24 of the air chamber 20 is provided with the ventilation portion 10 having the vent 12 to prevent the mold for molding the case 60 from having a complicated shape. it can. Further, by making the ventilation part 10 a separate part from the case 60, the capacity in the air chamber 20 needs to be changed depending on the capacity in the plug hole 90, but the configuration of the ventilation part 10 is changed. Since it is not necessary, it can be used for ignition coils of other models, and an ignition coil having excellent productivity can be obtained.

In addition, as shown in FIG. 2, the ventilation portion 10 matches the arrow x, y, and z directions with the arrow x, y, and z directions of the case 60, and the ventilation portion side fitting portion 14 from the direction of the arrow 1. By fitting the case side fitting part 28 and sliding the ventilation part 10, it is possible to obtain an ignition coil having excellent assemblability. Further, the gap 26 is formed in the case boundary wall 24, and the gap 26 is sealed by the case side wall 16 by attaching the ventilation portion 10, so that the high-pressure tower of the case 60 is sealed. The bottom surface on the 62 side and the side surface on the case boundary wall 24 side are reliably sealed, so that the mold resin 80 can be prevented from leaking out of the case 60. Further, when the ventilation portion 10 is not sufficiently attached, a gap generated between the gap portion 26 and the case side wall 16 is located on the opening surface 68 side of the case 60, so that an assembly operator The gap generated between the gap 26 and the case side wall 16 can be found by visual confirmation by the above, and defects can be suppressed in advance.

As a modification of the first embodiment, the shape of the air chamber 20 may be changed according to the amount of contraction of the air in the plug hole 90 due to the temperature change of the engine, or the opening of the air chamber 20 The position 22 may be changed depending on the position where the ignition coil 100 is mounted on the engine, the configuration of the engine, and the like. Further, the shape of the vent portion 10 may be changed so that the protector-side vent 12b is drawn directly to the protector inner peripheral portion 72 without passing through the boundary surface between the case 60 and the protector inner peripheral portion 72. Further, the vent portion 10 may be formed from a material other than PBT.

Further, the ventilation portion 10 and the case 60 may be fixed by bonding other than fitting, and the shape of the ventilation portion side fitting portion 14 and the case side fitting portion 28 may be any shape depending on design circumstances. You may change to Further, although the gap 26 is formed in the case boundary wall 24, the case side fitting portion 28 is directly formed on the case boundary surface 24 to be connected and fixed to the ventilation portion side fitting portion 14. Also good.

10: Ventilation part
12: Vent
12a: Vent (air chamber side)
12b: Vent (Protector side)
14: Fitting part (ventilation side)
16: Case side wall
20: Air chamber
22: Opening
24: Case boundary wall
26: Air gap
28: Mating part (case side)
30: Primary coil
40: Secondary coil
50: Central iron core
52: Outer iron core
60: Case
62: High-pressure tower
64: Flange
66: Connector
68: Case opening surface
70: Protector
72: Inner circumference
74: Spring
76: Spark plug
80: Mold resin
90: Plug hole
100: Ignition coil

Claims (5)

A coil portion comprising a primary coil, a secondary coil, and an iron core;
A case for accommodating the coil portion;
In an internal combustion engine ignition coil comprising a protector attached to the case to seal the plug hole,
An air chamber having an opening on the plug hole side is formed on the side surface of the case,
The air chamber includes a vent formed as a separate body from the case,
In the ventilation portion, a vent hole that connects the inside of the plug hole and the inside of the air chamber via a boundary surface between the protector and the case is formed.
The internal combustion engine ignition coil, wherein the ventilation portion is inserted and fixed from the opening side of the air chamber. The ignition coil for an internal combustion engine according to claim 1, wherein the ventilation portion is fixed to a case boundary wall between the case and the air chamber by fitting or bonding. The case boundary wall includes a gap that penetrates the case and the air chamber,
3. The ignition coil for an internal combustion engine according to claim 2, wherein a case side portion is formed in the ventilation portion so as to close the gap when the air chamber is mounted. The said ventilation | gas_flowing part arrange | positions the said ventilation hole opened to the said air chamber side close to the surface facing the said opening part of the said air chamber, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. Ignition coil for internal combustion engine. The ignition coil for an internal combustion engine according to any one of claims 1 to 4, wherein the ventilation part has the ventilation hole opened to the plug hole side disposed between the protector and the case. .

Images