JPH11144986A - Stick type ignition coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil, wherein avoiding a secondary spool from directly touching a rubber buffering member, an injection-mold material is surely filled over the entire periphery. SOLUTION: On an inner surface on a high-voltage side of a secondary spool 4, a high-voltage side positioning means 17 which concentrically positions a buffering member 15 with a gap against it is provided, while, on an outer surface of a low-voltage side of the buffering member 15, a low-voltage side positioning member 18, which concentrically positions the secondary spool 4 with a clearance against it is provided. The buffering member 15 is inserted in the secondary spool 4 to form a clearance, over the entire periphery between the secondary spool 4 and the buffering member 15. Filling an injection mold material allows a clearance to be filled with it, so that the contact between the secondary spool 4 and the buffering member 15 is avoided, and environmental stress cracks will not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stick-type ignition coil mounted in a plug hole of an engine, and more particularly to a stick-type ignition coil in which a secondary coil is disposed inside a primary coil.

[0002]

2. Description of the Related Art A stick-type ignition coil (hereinafter referred to as an ignition coil) has a rod-shaped central core disposed at the center, and a secondary spool made of a resin having a secondary coil wound around the core and a primary coil wound around the core. There is a known type in which a primary spool made of resin is disposed and a casting material (epoxy resin or the like) is filled in the housing of the ignition coil. The casting material has a purpose of ensuring insulation in the ignition coil, a purpose of preventing the winding of the coil from being broken by penetrating between the wire materials of the coil, and a purpose of preventing damage due to vibration.

[0003]

In the ignition coil, a secondary spool around the center core may be damaged due to a difference in expansion between the center core and surrounding members. Thus, a technique was found in which a cylindrical rubber cushioning member was mounted around the center core, and the difference in expansion was absorbed by the cushioning member to prevent breakage of the secondary spool (not a conventional technique).

On the other hand, when a polymer material such as plastic is brought into contact with an unsuitable substance (specific solid, gas, liquid, etc.) for a long time, a chemical change such as breaking or cross-linking of a molecular chain occurs, resulting in a decrease in strength. In some cases, damage may occur even when a slight load is applied. Such damage is called environmental stress cracking. As a combination that causes this environmental stress cracking, there is a combination of non-crystalline plastic PPE (polyphenylene ether) and rubber. When PPE and rubber are kept in contact for a long period of time, the PPE deteriorates and cracks are generated with extremely small stress. Will happen. Amorphous plastics such as PPE are deteriorated by contact with oil, a solvent, and the like in addition to rubber, and cause environmental stress cracking.

Here, for the secondary spool of the ignition coil, a modified PPE having a reliable adhesion to an epoxy resin is used for the purpose of ensuring the withstand voltage. After the epoxy resin injected into the ignition coil is cured, structures outside the secondary spool (secondary coil, epoxy resin, primary coil, outer core,
Due to the restraint of the housing and the like, tensile strain occurs in the circumferential direction of the secondary spool. This distortion is smaller than the tensile fracture strain of the secondary spool, and no crack is initially generated in the secondary spool.

However, PPE forming a secondary spool
Has a property of deteriorating due to long-term contact with rubber as described above, so that when a rubber cushioning member is mounted inside the spool to prevent damage to the secondary spool, If an epoxy resin layer is not interposed between the buffer member and the secondary spool, the secondary spool and the buffer member come into contact with each other, deteriorating the secondary spool, and causing environmental stress cracking at an intermediate portion of the secondary spool where stress is generated. There was a problem that occurred.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to reliably cast a casting material over the entire circumference so that a secondary spool does not directly contact a rubber cushioning member. It is to provide a chargeable ignition coil.

[0008]

According to the first aspect of the present invention, the casting material is filled over the entire circumference between the cushioning member and the secondary spool by the positioning means. Therefore, the secondary spool does not contact the cushioning member. Therefore, no matter which material is used for the secondary spool, there is no problem that environmental stress cracking occurs.

According to the second aspect of the present invention, the cushioning member and the secondary spool are positioned on the high pressure side, and from the high pressure side to the intermediate portion before the casting material is filled. A clearance is formed over the entire circumference between the buffer member and the secondary spool. For this reason, the casting material is reliably filled in the entire periphery of the intermediate portion in the axial direction between the cushioning member and the secondary spool, and there is no problem that environmental stress cracking occurs in the secondary spool.

[0010] According to the third aspect of the present invention, the cushioning member and the secondary spool are positioned on the low pressure side, and from the low pressure side to the intermediate portion before filling with the casting material. A clearance is formed over the entire circumference between the buffer member and the secondary spool. For this reason, the casting material is reliably filled in the entire periphery of the intermediate portion in the axial direction between the cushioning member and the secondary spool, and there is no problem that environmental stress cracking occurs in the secondary spool.

According to a fourth aspect of the present invention, by adopting the technique of the fourth aspect and providing six or more positioning projections at regular intervals, even if some of the projections are crushed due to a molding deviation, other pluralities are obtained. By the projections, a gap over the entire circumference is reliably formed between the cushioning member and the secondary spool.

According to the fifth aspect of the present invention, even if a secondary spool is formed by PPE having a reliable adhesion to an epoxy resin generally used as a casting material, the secondary spool is formed on the secondary spool. There is no problem that environmental stress cracking occurs.

[0013]

Next, embodiments of the present invention will be described with reference to examples and modifications. [Embodiment] FIGS. 1 to 7 show an embodiment.
The ignition coil 1 will be described with reference to FIG. The ignition coil 1 is mounted in a plug hole formed for each cylinder of the engine (not shown), and is electrically connected to an ignition plug (not shown). The ignition coil 1 includes a cylindrical housing 2 made of a resin material, and includes a central core 3, a secondary spool 4, a secondary coil 5, a primary coil 6, Next coil 7, Outer core 8
The casting material 9 is vacuum-filled in each gap.

The center core 3 has a cylindrical shape.
It is provided by laminating thin silicon steel sheets in the lateral direction (the direction perpendicular to the axial direction). At both ends of the center core 3, permanent magnets 3a, 3b are mounted.
b is mounted in a polarity opposite to the excitation pole of the center core 3.
The secondary spool 4 is a cylindrical bobbin for forming the secondary coil 5 and is positioned on the inner wall of the primary spool 6. The secondary spool 4 is modified so that its adhesion to the epoxy resin used as the casting material 9 is ensured. Molded by PPE (Fig. 1
reference). The secondary coil 5 is formed by winding a very thin coil wire coated with insulation around the outer periphery of the secondary spool 4 and is provided in a cylindrical shape. It is electrically connected.

The primary spool 6 is a bobbin for forming the primary coil 7, is positioned on the inner wall of the housing 2 and the outer core 8, and is formed of modified PPE, like the secondary spool 4. The primary coil 7 is insulated and coated, and is provided in a tubular shape by winding a coil wire thicker than the coil wire of the secondary coil 5. The primary coil 7 is electrically connected to an input terminal 11 described later on the low voltage side (upper side in FIG. 6). It is connected to the. The outer core 8 is mounted in contact with the inner wall of the housing 2. The outer core 8 is formed by rolling a thin silicon steel sheet into a cylindrical shape so as to form a slit for insulation at the start and end of winding.

A connector 10 for connecting an ignition coil is provided at the upper end of the housing 2 so as to protrude from the plug hole, and an input terminal 11 for supplying a control signal to the primary coil 7 is insert-molded on the connector 10. Or it is press-fitted. Note that a switching circuit (not shown) for supplying a control signal to the input terminal 11 is arranged outside the ignition coil 1.

The high voltage terminal 12 is insert-molded at the lower end of the housing 2 and is electrically connected to the spring 13. The spring 13 electrically connects to the ignition plug when the ignition coil 1 is mounted in the plug hole. The high voltage generated by the secondary coil 5
The voltage is applied to the ignition plug via the high voltage terminal 12 and the spring 13. A plug cap 14 made of rubber is mounted on the lower end opening of the housing 2, and the plug cap 14 is mounted on the ignition plug.

The casting material 9 enters into the gap in the housing 2 in which the members are assembled by vacuum filling, and ensures electrical insulation between the members. This prevents damage such as cracks and the like. The casting material 9 was made of an epoxy resin for the purpose of satisfying the insulating property, the fixing power, and the heat resistance.

Between the center core 3 and the secondary spool 4,
A cushioning member 15 is mounted to absorb a difference in expansion between the central core 3 and the surrounding members and prevent the secondary spool 4 from being damaged (see FIG. 1). The cushioning member 15 is made of rubber and has a cylindrical shape that covers the outer periphery of the center core 3, and absorbs a difference in expansion between the center core 3 and surrounding members by elastic deformation. In this embodiment, as shown in FIG.
A film 16 is provided between the coil 16 and the next coil 7, and is provided so as to separate the expansion difference between the inside and outside of the film 16.

As shown in FIG. 7, the space between the secondary spool 4 and the cushioning member 15 is filled with a casting material 9 for the purpose of preventing contact between the two members. Before the casting material 9 is filled in the ignition coil 1, a gap is formed over the entire circumference between the secondary spool 4 and the cushioning member 15, so that the space between the secondary spool 4 and the cushioning member 15 is reliably formed during the filling. Positioning means for filling the casting material 9 over the entire circumference is provided therebetween. The positioning means reliably guides the casting material 9 over the entire circumference of at least the intermediate portion (the portion where the environmental stress crack has occurred) in the axial direction between the secondary spool 4 and the cushioning member 15. ,
In this embodiment, the high-pressure side positioning means 17 (see FIG. 1) formed on the high-pressure side inner surface of the secondary spool 4 and the low-pressure side positioning means 1 formed on the low-pressure side outer surface of the cushioning member 15.
8 (see FIG. 1).

The high-pressure side positioning means 17 is shown in FIGS. 1 to 3, and comprises six high-pressure side projections 17a along the axial direction on the inner surface of the secondary spool 4 on the high pressure side. The six high-pressure side projections 17a are arranged at equal intervals.
As described above, the high-pressure side projection 1 serves as the high-pressure side positioning means 17.
By providing the six 7a, even if a molding displacement occurs on the high pressure side during molding of the secondary spool 4 and one high pressure side projection 17a is not formed, the high pressure side projections 17a on both sides of the secondary spool 4 make contact with the buffer member 15. A gap can be formed between them.
In other words, by providing six high-pressure side projections 17a, a gap can be reliably formed over the entire circumference between the secondary spool 4 and the buffer member 15 on the high-pressure side, and concentric positioning can be performed. As shown in FIG. 2, the six high-pressure side projections 17a are provided with a tapered portion 17b at the low-pressure side end so that the buffer member 15 can be inserted smoothly.

The low-pressure side positioning means 18 is shown in FIGS.
As shown in FIG. 5, the low-pressure side outer surface of the cushioning member 15 includes six low-pressure side projections 18a that bulge in an arc shape,
The six low-pressure side projections 18a are arranged at equal intervals. By providing the six low-pressure side projections 18a as the low-pressure side positioning means 18 as described above, even if a molding displacement occurs at the time of forming the cushioning member 15 and one low-pressure side projection 18a is not formed, the low-pressure side on both sides thereof is formed. 2 by the projection 18a
A gap can be formed with the next spool 4. In other words, the provision of the six low-pressure side positioning means 18 allows the secondary spool 4 and the cushioning member 15 to reliably form a gap over the entire circumference on the low-pressure side and to perform concentric positioning.

The high pressure side positioning means 17 allows the secondary spool 4 and the buffer member 15 to be positioned concentrically on the high pressure side via a gap, and the low pressure side positioning means 18 allows the secondary spool 4 and the buffer member 15 to be positioned on the low pressure side. 15 can be positioned concentrically via a gap, so that before filling with the casting material 9, 2
The next spool 4 and the cushioning member 15 are positioned concentrically via the gap. Thus, only by inserting the cushioning member 15 into the secondary spool 4, a gap is formed over the entire circumference between the secondary spool 4 and the cushioning member 15. When 9 is filled, the secondary spool 4
The casting material 9 is filled over the entire space between the secondary spool 4 and the cushioning member 15 at least in the axially intermediate portion (excluding the high-pressure side and the low-pressure side). Contact is reliably prevented.

(Effects of the Embodiment) As described above, the provision of the high-pressure side positioning means 17 and the low-pressure side positioning means 18 makes it possible to remove portions (specifically, parts other than the high-pressure side and the low-pressure side).
The casting material 9 is filled over the entire circumference between the secondary spool 4 and the cushioning member 15 at a portion other than the portion touched by the positioning means). Therefore, the modified PP is attached to the secondary spool 4.
Even if E is used, at least the intermediate portion in the axial direction
The contact between the next spool 4 and the cushioning member 15 is reliably prevented,
There is no problem that environmental stress cracking occurs in the secondary spool 4.

In this embodiment, an example is shown in which only the high-pressure side positioning means 17 is formed on the secondary spool 4. This is 2
When the low pressure side positioning means 18 is also formed on the next spool 4,
It is difficult to remove the secondary spool 4 from the mold.
In this embodiment, the low pressure side positioning means 18 is connected to the buffer member 15.
, The secondary spool 4 can be easily die-cut, and the productivity is excellent.

Further, in this embodiment, an example is shown in which only the low pressure side positioning means 18 is formed on the buffer member 15. This is because if the high-pressure side positioning means 17 is also formed on the buffer member 15, when the buffer member 15 is inserted into the secondary spool 4,
This is because the high-pressure side positioning means 17 slides on the inner wall of the secondary spool 4 to provide resistance over the entire insertion area, making assembly difficult.
Since 7 is located on the secondary spool 4, the sliding contact resistance occurs only at the end of insertion, and the assembling property is good.

[Modification] In the above embodiment, an example is shown in which both the high-pressure side positioning means 17 and the low-pressure side positioning means 18 are applied to the ignition coil 1.
7 or only one of the low-pressure side positioning means 18 may be provided. That is, the high-pressure side positioning means 1
7 to provide a gap over the entire circumference from the high pressure side to the middle portion, or use only the low pressure side positioning means 18 to provide a gap over the entire circumference from the low pressure side to the middle portion. May be.

In the above embodiment, the high-pressure side positioning means 1
7 is provided integrally with the secondary spool 4, but for example, a separate high pressure side positioning means 17 provided in a ring shape is
It may be mounted on the next spool 4 and used. In the above-described embodiment, an example is shown in which the low-pressure side positioning means 18 is provided integrally with the buffer member 15. However, for example, a separate low-pressure side positioning means 18 provided in a ring shape is mounted on the buffer member 15 and provided. Is also good.

In the above embodiment, the example using the outer core 8 has been described, but the present invention may be applied to an ignition coil not using the outer core 8. In the above-described embodiment, the example in which the permanent magnets 3a and 3b are mounted on the center core 3 has been described.
The present invention may be applied to an ignition coil in which the permanent magnets 3a and 3b are not mounted.

[Brief description of the drawings]

FIG. 1 is an assembly diagram of a secondary spool and a buffer member.

FIG. 2 is a sectional view of a main part of a secondary spool.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view of a main part of the cushioning member.

FIG. 5 is a view as viewed from B in FIG. 1;

FIG. 6 is a sectional view of an ignition coil.

FIG. 7 is a sectional view of a main part of the ignition coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ignition coil 2 Housing 3 Central core 4 Secondary spool 5 Secondary coil 6 Primary spool 7 Primary coil 9 Casting material 15 Buffer member 17 High pressure side positioning means 17a High pressure side projection 18 Low pressure side positioning means 18a Low pressure side projection

Claims (5)

[Claims] 1. A stick-type ignition coil in which a secondary coil is arranged inside a primary coil, a rod-shaped center core, and a cylindrical rubber cushioning member arranged on the outer periphery of the center core. A cylindrical secondary spool disposed around the buffer member and around which the secondary coil is wound; a casting material filled in a gap in the ignition coil; and a cushioning member and the secondary spool. Perform positioning,
Positioning means for forming a gap for filling the casting material over the entire circumference between the cushioning member and the secondary spool. 2. The stick-type ignition coil according to claim 1, wherein the positioning means is formed on an inner surface on a high pressure side of the secondary spool, and a gap extending over the entire circumference between the secondary spool and the cushioning member. A stick-type ignition coil characterized in that positioning is performed concentrically via a stick. 3. The stick-type ignition coil according to claim 1, wherein the positioning means is formed on an outer surface on a low-pressure side of the cushioning member, and has a full circumference between the secondary spool and the cushioning member. A stick-type ignition coil, which is positioned concentrically via a gap extending over a distance from the center to the center. 4. The stick-type ignition coil according to claim 1, wherein said positioning means comprises six or more projections provided at equal intervals in a circumferential direction. coil. 5. The stick type ignition coil according to claim 1, wherein the secondary spool is made of polyphenylene ether.