JP3608338B2 - Resin enclosed ignition coil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin-enclosed ignition coil for generating a high voltage necessary for ignition of an internal combustion engine.
[0002]
[Prior art]
As an example of a prior art of a resin-encapsulated ignition coil, a technique disclosed in Japanese Patent Laid-Open No. 2-333907 is known. As disclosed in this technology, a resin-encapsulated ignition coil has a primary spool wound with a primary coil, a secondary spool wound with a secondary coil, an iron core, a coil case, and insulation inside. It is composed of various parts such as a cured resin to be secured, and when the primary coil is subjected to current ON-OFF control, the secondary coil generates a high voltage.
[0003]
[Problems to be solved by the invention]
The ignition coil is not limited to the resin-encapsulated type, and the temperature during operation of the internal combustion engine rises, and when the operation stops, the ignition coil is cooled to the environmental temperature. That is, the ignition coil expands and contracts as the temperature rises and falls. As described above, the resin-encapsulated ignition coil is composed of parts such as a primary spool, a secondary spool, an iron core, a coil case, and a cured resin, and is repeatedly expanded and contracted due to a difference in thermal expansion / contraction rate of each component. In the meantime, a part of the component parts (particularly, a cured resin for insulation) is cracked, the insulation is interrupted, and electrical leakage may occur in the resin-encapsulated ignition coil.
[0004]
OBJECT OF THE INVENTION
The present invention has been made in view of the above circumstances, and its purpose is that an electrical leak occurs even if a component is expanded and contracted due to temperature rise and fall and cracking occurs. There is no reliable resin-encapsulated ignition coil.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the following technical means is adopted for the resin-encapsulated ignition coil of the present invention.
[Means of Claim 1]
The resin-encapsulated ignition coil expands and contracts as the temperature rises and falls. At that time, the secondary spool also expands and contracts in the axial direction. When the secondary spool expands and contracts in the axial direction, the secondary terminal fixed to the high pressure side of the secondary spool is also displaced in the axial direction. When the secondary terminal is displaced (especially when the secondary spool cools and contracts and the secondary terminal is displaced to the low pressure side), the cured resin covering the secondary terminal is directed from the end of the secondary terminal to the periphery. There is a possibility of breaking.
Therefore, by adopting claim 1 and providing a cylinder surrounding the outer periphery of the secondary terminal on the high pressure side of the secondary spool, for example, even if the cured resin cracks from the end of the secondary terminal toward the periphery, The crack stops at the inner surface of the cylinder. That is, even if the cured resin is cracked from the end of the secondary terminal toward the periphery, the high voltage applied to the secondary terminal does not leak to other parts such as the primary coil side. For this reason, the reliability of the resin-encapsulated ignition coil can be improved.
[0006]
[Means of claim 2]
By adopting claim 2 and providing a bent portion bent toward the low pressure side on the outer peripheral side of the secondary terminal, the outer peripheral end of the secondary terminal is separated from the opening end of the cylindrical body. For this reason, even if the cured resin cracks from the end of the secondary terminal toward the periphery, the crack can be reliably stopped at the inner surface of the cylindrical body, and the reliability of the resin-encapsulated ignition coil can be further improved. it can.
[0007]
[Means of Claims 3 and 4]
Since the core slit having the highest electric field of the outer peripheral core and the bald part are provided so as not to oppose each other, the core slit and the bald part are compared with the case where they are opposed to each other. The distance gets longer. That is, since the insulation distance between the core slit and the bald portion by the cured resin becomes long, even if a crack occurs in the cured resin, the possibility that the crack connects the core slit and the bald portion is low. Thus, since the possibility that the core slit and the bald portion leak due to cracking is suppressed to a very low level, the reliability of the resin-encapsulated ignition coil can be increased.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described using examples and modifications.
〔Example〕
This embodiment will be described with reference to FIGS. FIG. 1 is an assembly view of a resin-enclosed ignition coil.
The resin-encapsulated ignition coil 1 is roughly divided into a winding assembly 2, a case assembly 3 that accommodates the winding assembly 2, and an epoxy resin (corresponding to a cured resin) that is enclosed between the assembled winding assembly 2 and the case assembly 3. , Not shown).
[0009]
The winding assembly 2 is formed of a cylindrical resin primary spool 5 around which the primary coil 4 is wound, and a cylindrical resin made of a cylindrical resin around which the secondary coil 6 is wound coaxially. The secondary spool 7 and a resin connector 8 assembled on the low pressure side of the secondary spool 7.
The primary coil 4 is connected to the plus terminal in the connector 8 at the beginning of winding together with the winding end of the secondary coil 6, and is connected to the minus terminal in the connector 8 at the end of winding.
[0010]
As shown in FIG. 2B, a bald portion 7a protruding in the radial direction is integrally provided on the high pressure side of the secondary spool 7, and the secondary coil 6 is provided in the bald portion 7a. When winding, the winding on the winding start side is bald. Note that the winding at the beginning of the winding that has been bended by the bald portion 7a has a metal secondary terminal 10 fixed to the end of the secondary spool 7 on the high-pressure side, and then 2 shown in FIG. It is connected to the wound piece 10 a of the next terminal 10.
A locking hole 10b into which a projection 15a of a high-voltage terminal 15 described later is inserted is provided at the center of the secondary terminal 10, and four biting pieces 10c that bite into the protrusion 15a inserted into the locking hole 10b. Is formed.
[0011]
On the high pressure side of the secondary spool 7, as shown in FIG. 2B, a cylindrical body 7 b that surrounds the outer periphery of the secondary terminal 10 in a bag shape is provided. Although the cylindrical body 7b of this embodiment is provided integrally with the secondary spool 7, it may be attached to the high pressure side of the secondary spool 7 after being provided separately.
As shown in FIG. 2B, the outer peripheral side of the secondary terminal 10 surrounded by the cylindrical body 7b is bent toward the low pressure side by a bent portion 10d. The bent portion 10d of the present embodiment is provided in a gentle substantially dish shape so as to obtain a cross-sectional curve so that the epoxy resin is not cracked from the bent portion 10d.
[0012]
The case assembly 3 is a cylindrical coil case 11 into which the primary spool 5 is coaxially fitted, an insulating high-pressure tower 12 fixed to the high-pressure side, and an internal combustion engine fixed to the low-pressure side. Each of the members 13 is formed of resin.
In addition to the above resin members, the case assembly 3 includes an outer peripheral core 14 fitted on the inner peripheral surface of a cylindrical coil case 11 and a spark plug connecting high voltage terminal fixed inside the insulating high voltage tower 12. 15. The outer peripheral core 14 is a metal plate having a substantially C-shaped cross section provided with a core slit 14a along the axial direction.
[0013]
The core slit 14a of the outer peripheral core 14 is assembled so as to be shifted by 90 °, for example, so as not to face the same direction as the bald portion 7a described above. For this assembly, in this embodiment, the core positioning portion 11a for directing the core slit 14a in a predetermined direction with respect to the coil case 11 and the bald portion 7a for the coil case 11 in the predetermined direction are assembled. Secondary spool positioning means is used.
[0014]
The core positioning part 11a will be described. As shown in FIG. 3, a protruding core positioning portion 11 a that fits the core slit 14 a and positions the outer core 14 is provided on the inner surface of the coil case 11. Thereby, by assembling the outer peripheral core 14 in the coil case 11, the core slit 14 a is directed in a predetermined direction with respect to the coil case 11. The core positioning portion 11 a may be provided along the axial direction of the inner surface of the coil case 11 or may be provided so as to protrude from a part of the inner surface of the coil case 11.
[0015]
The secondary spool positioning means will be described. The connector 8 of the winding assembly 2 is provided with an assembly hole 8a into which two locking pieces 7c provided at the low-pressure end of the secondary spool 7 are fitted. By fitting the locking piece 7c into the assembly hole 8a, the bald portion 7a is directed in a predetermined direction with respect to the winding assembly 2. Further, the fixing member 13 of the case assembly 3 is provided with a positioning recess 13a for restricting the orientation of the connector 8. By fitting the connector 8 into the positioning recess 13a, a bald portion with respect to the coil case 11 is provided. 7a can be assembled in a predetermined direction. As a result, the core slit 14a and the bald portion 7a are assembled in different directions.
[0016]
Next, the operation of the resin-enclosed ignition coil 1 according to the present invention will be described.
The temperature of the resin-encapsulated ignition coil 1 assembled in the internal combustion engine and having the high-voltage terminal 15 connected to the spark plug is increased by the operation heat of the ignition coil itself and the transmitted heat of the internal combustion engine during operation of the internal combustion engine. When the operation stops, it is cooled to room temperature. As described above, the resin-encapsulated ignition coil 1 is repeatedly increased and decreased in temperature and expanded and contracted as the temperature increases and decreases.
[0017]
At that time, the secondary spool 7 also expands and contracts in the axial direction. When the secondary spool 7 expands and contracts in the axial direction, the secondary terminal 10 fixed to the high pressure side of the secondary spool 7 is also displaced in the axial direction. In particular, when the secondary spool 7 is cooled and contracts and the secondary terminal 10 is displaced to the low pressure side, the epoxy resin covering the secondary terminal 10 may break from the end of the secondary terminal 10 toward the periphery. Even if the epoxy resin cracks from the end of the secondary terminal 10 toward the periphery, the periphery of the secondary terminal 10 is surrounded by the cylinder 7b, so that the crack of the epoxy resin stops at the inner surface of the cylinder 7b.
[0018]
Further, since the outer peripheral side of the secondary terminal 10 is bent toward the low pressure side by the bent portion 10d, the outer peripheral end of the secondary terminal 10 is separated from the opening end of the cylindrical body 7b. For this reason, even if the epoxy resin is cracked from the end of the secondary terminal 10 toward the periphery, the probability that the crack extends to the outside of the cylindrical body 7b is small.
[0019]
On the other hand, when the resin-encapsulated ignition coil 1 expands and contracts as the temperature rises and falls, the epoxy resin sealed inside may break, particularly when contracting. In the resin-encapsulated ignition coil 1 of the present embodiment, the core slit 14a having the highest electric field of the outer peripheral core 14 and the bald portion 7a are assembled so as to be shifted by 90 ° so as not to face each other. The distance between the core slit 14a and the bald portion 7a is longer than when the bald portion 7a faces in the same direction. That is, since the insulation distance between the core slit 14a and the bald portion 7a by the epoxy resin is long, even if a crack occurs in the epoxy resin, the possibility that the crack connects the core slit 14a and the bald portion 7a is low.
[0020]
The effect of the present embodiment will be described.
Even if the epoxy resin cracks from the end of the secondary terminal 10 to the outside due to the expansion and contraction of the secondary spool 7 in the axial direction, the cracking stops at the inner surface of the cylindrical body 7b. Further, since the outer peripheral end of the secondary terminal 10 is separated from the opening end of the cylindrical body 7b by the bent portion 10d, even if the epoxy resin is cracked from the end of the secondary terminal 10 to the outside, the crack is not removed. The probability of extending outside is small. For this reason, the resin-encapsulated ignition coil 1 of this embodiment has a very low probability that the high voltage applied to the secondary terminal 10 leaks to other parts such as the primary coil 4 and obtains high reliability. Can do.
[0021]
Moreover, even if the epoxy resin sealed inside is cracked by expansion / contraction of the resin-encapsulated ignition coil 1, the core slit 14a having the highest electric field of the outer peripheral core 14 and the bald portion 7a are assembled with a 90 ° shift. Therefore, the possibility that the crack of the epoxy resin connects the core slit 14a and the bald portion 7a is extremely small. That is, in the resin-encapsulated ignition coil 1 of the present embodiment, the core slit 14a having the highest electric field of the outer peripheral core 14 and the bald portion 7a to which a high voltage is applied are extremely unlikely to leak and has high reliability. Sex can be obtained.
[0022]
[Modification]
In the above-described embodiment, an example in which the secondary coil 6 is disposed inside the primary coil 4 is shown, but conversely, the primary coil 4 may be disposed inside the secondary coil 6.
In the above embodiment, an example in which the iron core (the outer peripheral core 14) is arranged outside the primary coil 4 and the secondary coil 6 has been shown, but the iron core is arranged inside the primary coil 4 and the secondary coil 6. Also good.
In the above-described embodiment, an example in which the high voltage terminal 15 is arranged on the axis of the secondary coil 6 has been described. However, the high voltage terminal 15 may be provided so as to be shifted from the axis of the secondary coil 6.
[0023]
In the above embodiment, an example in which the periphery of the secondary terminal 10 is covered with the cylinder 7b is shown, but the periphery of the secondary terminal 10 may not be covered with the cylinder 7b. That is, you may provide so that Claim 4 may be employ | adopted instead of Claim 1.
In the above embodiment, the bent portion 10d is provided in the secondary terminal 10 and the outer peripheral side is bent toward the low pressure side. However, the secondary terminal 10 may be provided flat. That is, you may provide so that Claim 2 may not be employ | adopted.
[0024]
In the above-described embodiment, an example in which the core slit 14a and the bald portion 7a are assembled by shifting by 90 ° has been described, but the assembly may be performed by shifting to another angle such as 180 ° or 120 °. Further, the core slit 14a and the bald portion 7a may be assembled in the same direction. That is, you may provide so that Claim 3-5 may not be employ | adopted.
In the above-described embodiment, an example in which the core slit 14a and the bald portion 7a are surely shifted to a predetermined angle by the positioning means has been shown. 7a may be assembled so that it does not face the same direction. That is, you may provide so that Claim 5 may not be employ | adopted.
[Brief description of the drawings]
FIG. 1 is an assembly diagram of a resin-enclosed ignition coil.
FIG. 2 is an end view and a cross-sectional view of a secondary spool on the high pressure side.
3 is a cross-sectional view taken along the line II of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Resin enclosure type ignition coil 4 Primary coil 5 Primary spool 6 Secondary coil 7 Secondary spool 7a Bending part 7b Cylindrical body 10 Secondary terminal 10d Bending part 11 Coil case 11a Core positioning part 12 High voltage tower 14 for insulation Core 14a Core slit 15 High voltage terminal

Claims (5)

A primary spool around which a primary coil is wound;
A secondary spool around which a secondary coil is wound and fitted coaxially with the primary spool;
A coil case for storing the primary spool and the secondary spool;
A high voltage tower for insulation provided on the high voltage side of the coil case;
A high-voltage terminal fixed inside the high-voltage tower for insulation and for applying a secondary voltage to the spark plug;
A secondary terminal fixed to the high voltage side of the secondary spool and electrically connected to the secondary coil, and also electrically connected to the high voltage terminal;
In a resin-encapsulated ignition coil in which a cured resin is enclosed,
The resin-enclosed ignition coil according to claim 1, wherein a cylinder surrounding the outer periphery of the secondary terminal is provided on the high-pressure side of the secondary spool. The resin-encapsulated ignition coil according to claim 1,
The resin-enclosed ignition coil, wherein the outer peripheral side of the secondary terminal includes a bent portion bent toward the low-pressure side. The resin-encapsulated ignition coil according to claim 1 or 2,
The coil case has a cylindrical shape in which the primary spool and the secondary spool are fitted coaxially, and an outer peripheral core having a core slit along the axial direction is fitted on the inner peripheral surface thereof.
On the high pressure side of the secondary spool, a bald portion is provided for winding the winding of the secondary coil,
A resin-enclosed ignition coil, wherein the core slit and the bald portion are provided so as not to face each other. A primary spool around which a primary coil is wound;
A secondary spool around which a secondary coil is wound and fitted coaxially with the primary spool, and a bald portion on which the winding of the secondary coil is bald on the high voltage side;
A cylindrical coil case into which the primary spool and the secondary spool are fitted coaxially;
An outer peripheral core fitted with the inner peripheral surface of the coil case and provided with a core slit along the axial direction;
In a resin-encapsulated ignition coil in which a cured resin is enclosed,
A resin-enclosed ignition coil, wherein the core slit and the bald portion are provided so as not to face each other. In the resin-encapsulated ignition coil according to claim 3 or 4,
The coil case and the secondary spool include secondary spool positioning means for assembling the secondary spool in a predetermined direction with respect to the coil case,
An inner surface of the coil case includes a core positioning portion that fits into the core slit and positions the outer peripheral core, and is a resin-encapsulated ignition coil.

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