JP2002061559A - Ignition coil and ignition device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil superior in the durability and reliability capable of inhibiting the leakage generated between a secondary coil and a coil core, and preventing the corrosion of a coil case or the like accommodating a primary coil and the secondary coil, and an ignition device using the same. SOLUTION: This ignition coil 100 comprises a coil part 10 formed by accommodating the primary coil 12 and the secondary coil 14, and packing an insulating mold layer 16 inside of the coil case 15, and the coil core C having a center core part 20 and a yoke part 30, and the coil core C is mounted on the engine body by a mounting part while insulated from an engine body. The mounting part and an insulating packing part 60 for at least partially burying a gap S formed between the coil part 20 and the coil core C opposite to each other, are integrally formed by the injection molded with a high molecular material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a closed magnetic circuit type ignition coil and an ignition device using the same.

[0002]

2. Description of the Related Art An ignition coil is used to supply a high voltage of, for example, several tens of kV (high voltage for discharge) to a spark plug which ignites an air-fuel mixture which is guided into a combustion chamber of an engine by igniting sparks. . By the way, the ignition coil includes a coil core (iron core), and the shape of the coil core is various. Further, an ignition coil having an open magnetic path formed by the coil core (hereinafter referred to as an open magnetic path type ignition coil) is provided. And an ignition coil having a closed magnetic circuit (hereinafter, referred to as a closed magnetic circuit type ignition coil). However, in the open magnetic circuit type ignition coil, there is a concern that since the magnetic path is outside the coil core (in the atmosphere), the magnetic resistance is large, magnetic leakage occurs, and a loss occurs in the voltage supplied to the spark plug. Therefore, a closed magnetic circuit type ignition coil (see, for example, Japanese Patent Application Laid-Open No. 9-313226) is used to reduce magnetic leakage and suppress a loss of the supply voltage to the spark plug, of which a secondary coil is a primary coil. FIG. 7 shows a general cross-sectional structure of a closed magnetic circuit type ignition coil located outside the coil.

In FIG. 7, a closed magnetic circuit type ignition coil 150 is shown.
Are the coil part 110, the center core part 120, and the yoke part 1.
30. The coil part 110 has a shaft hole 115b.
The primary coil 112 and the secondary coil 1 are concentrically wound around the axis of the coil case 115 (that is, around the axial hole 115b) inside the coil case 115 having
14 are accommodated. The center core portion 120 is disposed inside the coil portion 110 along the axis of the coil case 115 (that is, along the shaft hole 115b). The yoke section 130 connects both ends of the center core section 120 outside the coil section 110 to form a closed magnetic path M together with the center core section 120. In the coil section 110, a primary coil 112 is wound around the outer periphery of a cylindrical bobbin 111, and a secondary coil 114 is wound around the outer periphery of a cylindrical bobbin 113. I have.
The primary coil 112 and the secondary coil 114 are
The next coil 112 is housed in the coil case 115 in a form of being wound concentrically around the axis of the resin coil case 115 so as to be located inside. Then, the insulating resin layer 116 injected and solidified in the coil case 115 is formed.
As a result, both the coils 112 and 114 and the coil case 11
The gaps between them are filled and integrated. In addition, 140 is a high voltage tower for conducting with the high voltage side of the secondary coil 114 and extracting the high voltage to the outside (for example, a spark plug), and 141 is a high voltage terminal.

On the other hand, a center core portion 120 to be disposed inside the coil portion 110 and a yoke portion 130 to be disposed outside the coil portion 110 are composed of two E-shaped laminated silicon steel plates. The closed coil M is formed by opposing the legs of the coil core C to each other. The center core portion 120 is provided with a gap G for adjusting the mutual inductance of the closed magnetic circuit M at a position facing the central leg of the E-shaped coil core C. Further, the yoke portion 130 has mounting holes H at four corners for mounting the closed magnetic circuit type ignition coil 150 at the mounting position of the ignition coil of the engine body. Therefore, the closed magnetic circuit type ignition coil 150 is attached to the attachment position via the attachment hole H formed in the yoke portion 130 and the fastener such as a bolt inserted into the attachment hole H, and the engine is grounded. The coil core C is connected to the main body and grounded.

[0005]

In the coil portion 110 of the closed magnetic circuit type ignition coil 150, for example, the following two problems arise from the viewpoint of durability.

(1) Deterioration of insulation due to increase in electric field strength In the closed magnetic circuit type ignition coil 150, the ignition coil 15 is generally provided by a mounting hole H formed in the yoke portion 130.
The ground point is the coil core C in order to attach the coil itself to the engine body. However, when the coil core C is used as the ground point, the distance L between the high voltage side of the secondary coil 114 and the ground point cannot be made large because of the structure.
When a high voltage is generated in the next coil 114, the electric field strength at the distance L often increases (for example, it reaches 20 kV / mm or more). Therefore, the secondary coil 114
If the coil case 115 or the insulating resin layer 116 (the dielectric breakdown strength) located between the coil coil C and the coil core C cannot withstand the increase in the electric field intensity, the electric field leaks between the secondary coil 114 and the coil core C. May occur.
In other words, the discharge voltage increases with the consumption of the electrodes of the spark plug, but the cause of such an increase in the discharge voltage is directly reflected in the increase in the electric field strength between the secondary coil 114 and the coil core C. . Therefore, when the spark plug is used continuously for a long time under the condition where the discharge voltage of the spark plug becomes high, a leak occurs between the secondary coil 114 and the coil core C, and the coil case 115 and the insulating resin layer 11
Of the ignition coil 1
The durability of 50 itself will be reduced.

(2) Corrosion of coil by corona discharge ...
... In the closed magnetic circuit type ignition coil 150, the electric field intensity between the coil core C, which is a conductive portion, and the secondary coil 114 that generates a high voltage is large. During use, there is a case where air existing in the gap S is ionized and corona discharge occurs. In a closed magnetic circuit type ignition coil 150 in which the secondary coil 114 is located outside the primary coil 112 as shown in FIG. 7, the gap between the inner surface 130a of the yoke portion 130 and the outer surface 115a of the coil case 115 opposed thereto is provided. Corona discharge easily occurs in the gap S. In other words, in such a type,
Of the gap S formed between the coil section 110 and the coil core C, a portion where the corona discharge is expected to occur is a gap between the inner surface 130a of the yoke portion 130 and the outer surface 115a of the coil case 115 opposed thereto. is there. When the ignition coil 150 is used for a long period of continuous use, the coil case 115 and the insulating resin layer 116 are deteriorated by heat generated by corona discharge and ozone generated during corona discharge,
Erosion of the resin constituting the coil case 115 and the insulating resin layer 116 gradually progresses, and eventually causes dielectric breakdown.

In recent years, stationary gas engines have become widespread. A stationary gas engine is an energy supply source of a cogeneration system that uses both exhaust heat and combustion heat to improve energy use efficiency.
It is used in factories, buildings, hospitals, hotels, and the like, and is used in homes and offices as a driving source of a gas heat pump (GHP) for operating a small air conditioner.

In such a stationary gas engine, reliability is first required since it is directly connected to a so-called lifeline depending on the use mode. In other words, the operating time of the stationary gas engine is much longer than that of an automobile gasoline engine or the like (for example, continuous operation for 24 hours).
For this reason, the ignition coil (closed magnetic circuit type ignition coil) is required to have sufficient durability especially in view of the above (1) and (2). In other words, since gas engines use gaseous fuel, they have higher insulation than liquid fuel, such as gasoline.Therefore, measures have been taken to reduce the discharge voltage by narrowing the gap of the spark discharge gap of the spark plug. I have. However, since the discharge voltage gradually rises with the consumption of the electrodes of the spark plug (necessarily also in the ignition coil), the maximum voltage generating capability of the secondary coil must be set higher than that of the gasoline engine. In addition, since the coil case is used for long-time continuous operation, the insulation property is degraded (dielectric breakdown) due to the increase in the electric field strength described in (1), and the coil case is generated due to the corona discharge described in (2). Etc. are likely to occur.

Therefore, an object of the present invention is to increase the maximum voltage generating capability of the secondary coil due to, for example, an increase in the discharge voltage of the spark plug, and to maintain the maximum voltage of the secondary coil even under conditions of continuous operation for a long time. Along with suppressing the leakage occurring between the next coil and the coil core, the occurrence of corona discharge between the coil portion and the coil core is suppressed,
An object of the present invention is to provide an ignition coil which can suppress erosion of a coil case or the like accommodating a primary coil and a secondary coil and which is excellent in durability and reliability, and an ignition device using the ignition coil.

[0011]

Means for Solving the Problems and Functions / Effects In order to solve the above-mentioned problems, an ignition coil according to the present invention is provided in such a form that it is wound concentrically around the axis of the coil case inside the coil case. A coil portion in which a secondary coil and a secondary coil are housed and filled with an insulating mold layer; a center core portion disposed along the axis inside the coil portion; and the center core portion outside the coil portion A coil core having a yoke portion that forms a closed magnetic path together with the center core portion by connecting both end sides of the ignition coil portion, and the ignition coil is insulated from the engine body. Thus, the gap formed between the mounting portion for mounting to the engine body and the coil portion and the coil core facing each other is reduced. And Kutomo partially fills the insulating filling unit, characterized in that it is formed by integrally injection molding at polymer material.

That is, an ignition coil according to the present invention includes a coil portion which accommodates a primary coil and a secondary coil in a coil case and is filled with an insulating mold layer, and a coil core having a center core portion and a yoke portion. So that the coil core is insulated from the engine body, and is attached to the engine body by an attachment portion formed by integral injection molding of a polymer material together with an insulative filling portion described later. Therefore, it is not necessary to attach the coil core directly to the engine body while grounding it as in the related art. In other words, the ignition coil itself is mounted so that the coil core is insulated from the engine body by the mounting portion, so that the distance between the secondary coil and the ground point is not limited and is adjusted to the position where the mounting portion is formed. Be free. Therefore, the electric field intensity between the secondary coil and the ground point can be effectively reduced. Therefore, the maximum voltage generating capability of the secondary coil increases due to, for example, an increase in the discharge voltage of the spark plug, and even if the secondary coil is subjected to continuous operation for a long time, the leakage between the secondary coil and the coil core occurs. The durability of the ignition coil can be improved without occurrence of cracks.

Further, as described above, the mounting portion is integrally formed of a polymer material together with the insulating filler by injection molding, so that the mounting portion is not limited to the coil core as in the prior art, and the ignition coil mounting position is not limited. It is possible to easily and freely adjust the position, shape, number, and the like of the mounting portions according to the shape, the number of mountings, and the like. Further, when the mounting portion is a coil core as in the related art, when the position of the mounting portion is changed according to the engine body, it is necessary to change the shape of the entire ignition coil including the coil core. However, in the present invention in which the mounting portion is integrally injection-molded with a polymer material, it is possible to cope with a change in the mounting position on the engine body only by adjusting the integrated injection-molded portion, including the coil core. The shape change can be minimized, and the cost can be reduced.

Further, in the present invention, the insulating filling portion formed of a polymer material together with the mounting portion fills a gap formed between the coil portion and the coil core, so that the coil portion by corona discharge ( In particular,
Deterioration and erosion of the coil case, the insulating mold layer, etc.) are less likely to occur, and the durability of the ignition coil can be improved.

Here, the insulating filler portion partially fills a gap formed between the coil portion and the coil core when the coil portion and the coil core face each other. This means that at least a portion of the gap formed between the coil portion and the coil core where corona discharge is expected to occur is filled. The portion where the corona discharge is scheduled to occur, in other words, in the gap formed between the coil portion and the coil core, the local potential gradient in the electric field direction of the gap is caused by the air layer filling the gap. This is the part where the dielectric strength is higher. That is, by filling the air layer portion (gap) between the coil portion and the coil core satisfying the condition for generating the corona discharge in the ignition coil with the insulating filling portion, the occurrence of the corona discharge can be prevented. The dielectric strength of the air layer depends on the rate of increase of the applied voltage.
It fluctuates depending on time, temperature, humidity, air pressure, etc. of the air layer.
/ Mm.

Specifically, in the case of a type of ignition coil in which the secondary coil is located outside the primary coil, the insulating filler portion is formed between the outer surface of the coil portion and the inner surface of the yoke portion facing the coil portion. It is necessary to fill at least the gap formed therebetween. In this type, since the high voltage side of the secondary coil is relatively located outside the coil portion, corona discharge occurs in a gap formed between the outer surface of the coil portion and the outer surface of the yoke portion facing the coil portion. Easier to do.

On the other hand, in the case of an ignition coil in which the secondary coil is located inside the primary coil, the insulating filler portion is formed between the inner surface of the coil portion and the outer surface of the center core portion opposed thereto. It is necessary to fill at least the gap to be made. In this type, since the high voltage side of the secondary coil is relatively located inside the coil portion, corona discharge is generated in a gap formed between the inner surface of the coil portion and the outer surface of the center core portion opposed thereto. Easier to do.

If the insulative filling portion fills substantially the entire gap formed between the coil portion and the coil core facing the coil portion, the type in which the secondary coil is located outside the primary coil is used. However, the present invention can be equally applied to the type in which the former is located inside the latter, and the versatility can be improved.

Further, when the insulating coating covering almost the entire coil core is formed by integral injection molding of a polymer material together with the insulating filling portion and the mounting portion, it is possible to prevent impact such as corrosion due to rust or dropping. The coil core can be protected from damage due to.

In order to improve heat resistance (softening point), an insulating filler (for example, glass fiber) may be added to the thermoplastic resin as a polymer material used in the integral injection molding. And the compounding ratio of the insulating filler is 10 to
40% by weight and its softening point is 120 ° C
By doing so, the durability of the ignition coil can be further improved.

If the compounding ratio of the insulating filler exceeds 40% by weight, the fluidity of the thermoplastic resin at the time of integral injection molding deteriorates, and for example, the insulating filler cannot fill a predetermined gap. There is a risk. When the compounding ratio of the insulating filler is less than 10% by weight, the reliability of the ignition coil may be reduced in terms of heat resistance. Also,
If the softening point of the thermoplastic resin is lower than 120 ° C., the reliability of the ignition coil may decrease in terms of heat resistance.

Here, as the thermoplastic resin used in the integral injection molding, polybutylene terephthalate resin (hereinafter, referred to as PBT resin), polyphenylene sulfide resin (hereinafter, referred to as PPS resin), and polyethylene terephthalate resin (hereinafter, referred to as PET resin) are used. It is desirable to select at least one of them. Each of these resins has extremely good fluidity even in a state where an insulating filler such as glass fiber is blended, and is excellent in moldability. In addition, generally, as a resin for integral injection molding, P with glass fiber is used.
BT resin is most widely used and has a softening point of 20
0-220 ° C.

Next, the ignition device according to the present invention is mounted on the engine body and is electrically connected to the secondary coil of the ignition coil. And a spark plug that generates a spark discharge when supplied with a high voltage for use.

As described above, by dramatically improving the durability (life) of the ignition coil, it is possible to contribute to the improvement of the durability of the ignition device. Further, since the ignition coil is excellent in reliability, a high voltage for discharge can be generated by the ignition coil without loss, and spark discharge can be reliably generated by the spark plug. Therefore, if the ignition device is used in a stationary gas engine requiring high reliability and sufficient durability, the features of the present invention can be exhibited to the maximum.

[0025]

Embodiments of the present invention will now be described with reference to the embodiments shown in the drawings. FIG. 1 shows a gas engine ignition device 400 as an embodiment of the ignition device of the present invention, and this engine E is applied to a stationary gas engine. The igniter 400 includes a spark plug 200 that ignites a gaseous fuel (air-fuel mixture) that is guided into a combustion chamber CR of an engine E, and discharge corresponding to a discharge voltage required for spark discharge by the spark plug 200. Magnetic circuit type ignition coil 100 (hereinafter, simply referred to as an ignition coil) for supplying a high voltage for use to a spark plug 200
And a high-voltage cord 300 for transmitting the high voltage at this time from the ignition coil 100 to the spark plug 200. However, in the direct ignition type in which the ignition coil 100 is directly connected to the spark plug 200, the high-pressure cord 300 is unnecessary.

The ignition coil 100 shown enlarged in FIG.
A mounting portion 70 integrally formed of a thermoplastic resin (for example, PBT resin) together with an insulating covering portion 50 that covers substantially the entirety of a main body portion 40 (see FIG. 4) described later with almost no gap.
Thereby, it is fixed to the ignition coil mounting position of the engine body EB. Specifically, a fastener 72 such as a bolt is inserted into the mounting hole 71 of the mounting portion 70 and screwed into a screw hole formed in the engine main body EB to thereby form the ignition coil 100.
Is fixed to the ignition coil mounting position (see FIG. 4). A metal reinforcing ring 73 is fitted to the inner wall surface of the mounting hole 71,
The mounting portion 70 is reinforced so as not to be crushed by the fastening force of the fastener 72. Attachment part 7 to insulating coating part 50
The position, shape, number, etc. of 0 can be easily and freely adapted to various ignition coil mounting positions by appropriately adjusting the ignition coil mounting position in the case of integral injection molding described later. In addition, 1 is a primary coil described later (see FIG. 4).
One end of a positive input code 5 is connected to the positive input terminal 4, and one end of the negative input code 3 is connected to the negative input terminal 2. The other end of the + input cord 5 is connected to a + terminal of a battery (not shown),
The other end of the negative input cord 3 is connected to a collector of an igniter (not shown).

A high-voltage tower 90 projecting from the main body 40 in one direction includes a high-voltage terminal 91 and a high-voltage protection unit 92.
And A high voltage terminal 91 for conducting to a high voltage side of a secondary coil (see FIG. 4) to be described later, connecting one end of the high voltage cord 300, and extracting a high voltage of the secondary coil to the outside.
Is integrally formed with a coil case described later (see FIG. 4).

Returning to FIG. 1, the spark plug 200 includes a cylindrical metal shell 201, an insulator 202 fitted inside the metal shell 201, a center electrode 203 provided inside the insulator 202, and one end of the metal shell. And a ground electrode 204 or the like, the other end of which is bent back to the side and the side surface of which is arranged to face the tip of the center electrode 203. A spark discharge gap g is formed between the tip surface of the center electrode 203 and the side surface of the ground electrode 204. Then, the screw portion 205 formed on the metal shell 201 is screwed into the cylinder head SH of the engine E, so that the spark discharge gap g protrudes into the combustion chamber CR. Center electrode 203
A plug-side terminal 206 is formed at the end opposite to the side on which the spark discharge gap g is formed, and the other end of the high-voltage cord 300 is connected thereto.

Next, the ignition device 400 shown in FIG.
FIG. 2 shows an embodiment of the closed magnetic circuit type ignition coil 100 according to the present invention.
5 to FIG. 2 is a perspective view, FIG. 3 is a plan view, FIG. 4 is a sectional view taken along the line XX in FIG. 3, and FIG. 5 is a sectional view taken along the line YY in FIG. Hereinafter, the configuration of the closed magnetic circuit type ignition coil 100 will be described mainly with reference to FIGS. 4 and 5.

The main body 40 of the ignition coil 100 includes a primary coil 12 and a secondary coil 14 inside a coil case.
And a center core portion 20 arranged inside the coil portion 10 along the axial direction thereof.
And a yoke portion 30 that connects both ends of the center core portion 20 outside the coil portion 10 to form a closed magnetic path M together with the center core portion 20. In the coil portion 10, one outer periphery of a cylindrical primary bobbin 11 made of a thermoplastic resin is provided.
A secondary coil 12 is wound around the secondary bobbin 13 and has a plurality of winding grooves.
The next coil 14 is wound. Primary coil 12
Is an enameled wire having a wire diameter of 0.3 to 1.0 mm for a total of 100
It is laminated and wound about 200 times. On the other hand, the secondary coil 14
In this method, an enameled wire having a wire diameter of 0.03 to 0.1 mm, which is thinner than this, is divided and wound in a total of about 5000 to 20,000 times.

The primary coil 12 and the secondary coil 14
Are concentrically housed in a coil case 15 made of a thermoplastic resin (for example, PBT resin) so that the primary coil 12 is positioned inside, and injected into the coil case 15 and cured by heating. Layer (for example, epoxy resin layer) 16
With the (insulating mold layer), the gap between the coils 12 and 14 and the coil case 15 is filled and integrated. Here, the thermosetting insulating resin layer 16 has the two coils 1 inside the hollow coil case 15 before the injection molding.
It can be formed by arranging 2, 14 and the like at predetermined positions and vacuum impregnating a thermosetting resin such as an epoxy resin in a liquefied state. In this way, by impregnating the thermosetting resin with the vacuum, the corners in the coil case 15 can be filled with the insulating resin, so that the insulation in the coil case 15 can be reliably obtained.

On the other hand, the center core portion 20 and the yoke portion 30 are formed of two U-shaped iron cores C in which a plurality of silicon steel plates C0 are laminated.
The (coil core) legs are formed to face each other to form an annular shape, and a closed magnetic path M is formed. Therefore, the coil case 15 of the coil unit 10 is located in the inner space surrounded by the closed magnetic path M so as to surround the center core unit 20 by the inner wall surface of the shaft hole 15b at the center. The center core portion 20 is provided with a gap G for adjusting the mutual inductance of the closed magnetic circuit M at a position facing the center leg of the U-shaped iron core C, and the gap G is adjusted to, for example, 1 mm. It is filled with a non-magnetic spacer 25 made of a curable resin (for example, an adhesive mainly composed of an epoxy resin). The non-magnetic spacer 25 is used when the integral molding 80 is formed by integral injection molding.
The iron core C is pressed from the outside by the injection pressure of the molding material (for example, PBT resin), thereby preventing the gap G from becoming narrower than a set value and changing the mutual inductance (so-called gap G collapse phenomenon). . That is,
Since the non-magnetic spacer 25 needs to be hardened before the integral injection molding to maintain the gap G at a predetermined value and not change its dimensions due to a temperature rise during the integral injection molding, the non-magnetic spacer 25 is made of epoxy resin or the like. It is desirable to use a thermosetting resin.

The main body 40 constructed as described above is made of a thermoplastic resin (for example, PBT resin, PPS resin or PET).
Almost the entire periphery is covered with an insulating covering portion 50 made of resin or the like. A gap S formed between the coil portion 10 and the iron core C (the center core portion 20 and the yoke portion 30) inside the closed magnetic path M is formed of a thermoplastic resin (for example, a PBT resin, a PPS resin, or a PET resin). And filled with an insulating filling portion 60 made of. The insulating filling portion 60 includes the insulating covering portion 50 and the mounting portion 70.
And an integral molding 80 is formed. Incidentally, the integrally molded portion 80 is formed by an insert molding method in which the main body 40 is embedded in a mold in advance, and a thermoplastic resin material is injected into the mold. Therefore, in this specification, “integral injection molding” is used synonymously with “insert molding”.

Next, a method for manufacturing such an ignition coil 100 will be described. (1) Assembling process of the coil unit 10 A secondary bobbin 13 wound with a secondary coil 14 is overlapped on the outside of the primary bobbin 11 wound with the primary coil 12, and a thermoplastic resin (for example, PBT resin) ), The coil part 10 is assembled by covering the coil case 15 (see FIG. 4) which is formed in advance by insert molding and has the shaft hole 15b. The primary coil 12 and the secondary coil 14 are housed inside the coil case 15 in a form of being concentrically wound around the axis of the coil case 15 (that is, around the shaft hole 15b) (see FIG. 4). ).

(2) Step of assembling the main body 40 and disposing the non-magnetic spacer 25 The shaft hole 1 formed along the axial direction of the coil case 15
5b, while inserting the legs of the two U-shaped iron cores C to form the center core portion 20, the coil portion 10 (the coil case 1).
The yoke part 30 is formed outside of 5), and the main body part 40 is assembled. A gap G is formed at an axially intermediate portion of the center core portion 20 formed by abutting the legs of the two U-shaped iron cores C, and the legs on the yoke 30 side are integrally formed into an annular shape. At this time, the gap G is filled by applying a non-magnetic spacer 25 made of an adhesive mainly containing a thermosetting resin (for example, an epoxy resin) to the leg of the one U-shaped iron core C.

(3) Step of Injecting Insulating Resin Material into Coil Case 15 The assembled main body 40 is put into a mold, and a thermosetting insulating resin (for example, epoxy resin) liquefied inside the coil case 15 while being impregnated in a vacuum. Inject).

(4) Step of Heat-Curing Non-Magnetic Spacer 25 and Insulating Resin Layer 16 The main body 40 placed in the mold is heated, and the non-magnetic spacer 25 is heat-cured to maintain the gap G at a predetermined value. Then, the thermosetting insulating resin material is cured by heating to form the thermosetting insulating resin layer 16.

(5) Integrated Injection Molding (Insert Molding) Step (See FIG. 6) The main body 40 and the reinforcing ring 73 (see FIG. 2) are arranged at predetermined positions so as to be embedded in the mold D. After the mold D is clamped, the PBT resin material P softened at a material temperature of about 220 to 260 ° C. is injected into the mold D at an injection pressure of about 5 to 10 MPa. At this time, the PBT resin material P is applied to the coil portion 10 and the iron core C (the center core portion 20 and the yoke portion 3).
0) to fill the gap S formed between
0 and an insulating coating 50 covering the main body 40.
Is formed, and the mounting portion 70 together with the reinforcing ring 73 is formed.
And these are integrated into an integrally formed part 80 (see FIG. 4). At this time, if a mounting hole is formed in the iron core C as in the related art, the PBT resin material P flows into the mounting hole 65 as well. Then, as in the normal injection molding process, the ignition coil 100 is taken out through each process of pressure-holding → cooling → release. Thereby, the insulating covering portion 50, the insulating filling portion 60, and the mounting portion 70 are integrally injection-molded as an integrated molding portion 80 made of PBT resin.
However, the PBT resin material P contains 10 to 40% by weight of glass fiber as an insulating filler (for example, 15 or 3%).
0% by weight) and the softening point is adjusted to be 200 ° C. or higher.

Of the integrally molded part 80, the insulating coating part 50
Covers almost the entirety of the main body 40,
It has a rust prevention function and a protection / buffer function against impacts such as falling.

Regarding the insulating filling portion 60, the following point is noted. That is, in the type in which the secondary coil 14 is concentrically wound outside the primary coil 12 as in the present embodiment, since the high voltage side of the secondary coil 14 is relatively located outside the coil portion 10, Corona discharge easily occurs in a gap S formed between the outer surface 10a of the coil portion 10 (the outer surface 15a of the coil case 15) and the inner surface 30a of the yoke portion 30 facing the outer surface 10a. By the way, since the injection molding is performed using the PBT resin material P containing glass fiber having good fluidity, the flow of the PBT resin material P in the mold D is extremely smooth. Therefore, the coil case 15
Outer surface 15a and the inner surface 30 of the yoke portion 30 facing the outer surface 15a
The PBT resin material P spreads over the gap S formed between the PBT resin material P and the PBT resin material P. As a result, the insulating filling portion 60 is formed so as to fill the gap S formed between the coil case 15 and the thermosetting insulating resin layer 16 (coil portion 10) and the iron core C opposed thereto. Corona discharge can be reliably prevented from occurring.

On the other hand, the mounting portion 70 serving as a ground point for grounding the engine main body EB is provided with the iron core C (the main body portion 40).
Are formed by integral injection molding together with the insulating filling portion 60 (furthermore, the insulating coating portion 50) while insulating.
Thereby, the mounting hole of the iron core C as in the prior art
There is no need to attach the main body 40 to the engine main body EB while grounding it.
Move to Therefore, the distance between the secondary coil 14 and the ground point is longer than the distance L between the conventional secondary coil 14 and the iron core C (see FIG. 4), and the secondary coil 14 and the mounting portion 7
0 (the reinforcing ring 73) (see FIG. 5). As a result, the intensity of the electric field between the secondary coil 14 and the ground point (reinforcement ring 73) is reduced, and leakage is less likely to occur. The iron core C is not grounded to the engine body EB, and is almost entirely covered with the insulating coating portion 60.
It is held in a state separated from the surface of the engine body EB.

By the way, when performing integral injection molding using a thermosetting resin such as an epoxy resin, for example, the thermosetting resin is relatively larger in heat shrinkage than the thermoplastic resin, and the thickness of the insulating coating portion 50 varies. The thinning phenomenon easily occurs.
Then, when the ignition coil 100 is repeatedly subjected to the thermal cycle, thermal stress is concentrated on the thin portion of the insulating coating portion 50, and there is a possibility that cracks or the like may occur (this is referred to as a decrease in heat cycle resistance). On the other hand, in the insulative coating portion 50 that is integrally injection-molded using a thermoplastic resin, the thickness variation is suppressed and the thickness is prevented from being reduced, so that the appearance becomes beautiful and the heat cycle resistance is improved. Is improved.

Next, based on FIG. 9 schematically showing the positional relationship between the coil portion 10 and the iron core C, a gap formed between the coil portion 10 and the iron core C and to be filled by the insulating filling portion 60 will be described. S will be described. Coil part 10 and iron core C
The portion where the corona discharge is scheduled to occur in the gap S formed between them by opposing each other differs as follows depending on the type of the ignition coil. FIG.
As apparent from the above, what has been described as an embodiment of the present invention belongs to the type (1).

(1) In the type in which the secondary coil 14 is located outside the primary coil 12, the high voltage side of the secondary coil 14 is located relatively outside the coil section 10. For this,
Inside the closed magnetic circuit M, the outer surface 10a of the coil portion 10
Corona discharge is likely to occur in the gap S1 formed between the (outer surface 15a of the coil case 15) and the inner surface 30a of the yoke 30 opposed thereto (see FIG. 9B). Therefore, in this type of ignition coil, the insulating coating 60
Needs to fill at least this gap S1.

(2) In the type in which the secondary coil 14 is located inside the primary coil 12, the high voltage side of the secondary coil 14 is located relatively inside the coil unit 10. For this,
Inner surface 10b of coil portion 10 (axial hole 1 of coil case 15)
Corona discharge is likely to occur in the gap S2 formed between the inner wall surface 5b) and the outer surface 20a of the center core portion 20 opposed thereto (see FIG. 9C). Therefore, in this type of ignition coil, it is necessary that the insulating coating portion 60 fill at least the gap S2.

(Experimental Example) In order to confirm the effect of the present invention, an endurance test of an ignition coil was performed. First, two main bodies 40 shown in FIG. 4 were prepared, and one of the main bodies 40 was subjected to the following treatment to prepare two kinds of test articles. (A) The integrated injection molding process shown in FIG.
This was performed at an injection pressure of 8 MPa using a PBT resin material at a temperature of 0 ° C. to obtain an ignition coil 100 in which an integrally molded portion 80 was formed in the main body 40. [Example A] (B) In the other ignition coil, the main body 40 was left as it was. [Conventional example B]

Next, the test products A,
B was electrically connected to a spark plug via a high-voltage cord connected to the high-voltage tower 90, and after placing them in a high-temperature bath, a spark discharge was generated by the spark plug to perform a continuous durability test. . The test was performed by counting the number of times of driving (the number of times of discharge) until the ignition coil failed due to insulation breakdown. The test conditions are as follows.・ Ambient temperature: 80 ° C. ・ Drive frequency: 150 Hz ・ Average discharge voltage: 30 kV

FIG. 8 shows the test results. In FIG. 8, the number of times of failure drive (durability) of the ignition coil is about 3 in Example A.
500 million times, and about 900 million times in Conventional Example B. It can be seen that Example A has about four times the durability of Conventional Example B.

In the ignition coil according to the present invention, the shape of the iron core is not limited to the U-shape shown in the embodiment, but may be applied to other shapes such as the E-shape shown in FIG. Also, the gap in the closed magnetic circuit is formed in the center core in the embodiment,
It may be formed in the yoke part, or may be formed in plural.
Further, the ignition coil according to the present invention is applicable to a so-called inner iron type and an outer iron type in the relative positional relationship between the coil portion and the iron core.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an ignition device for a gas engine which is an embodiment of an ignition device according to the present invention.

FIG. 2 is a perspective view of an ignition coil used in the ignition device of FIG. 1;

FIG. 3 is a plan view of the ignition coil of FIG. 2;

FIG. 4 is a cross-sectional view of the ignition coil of FIG.

FIG. 5 is a sectional view of the ignition coil of FIG.

FIG. 6 is an explanatory view showing an integral injection molding step of the ignition coil of FIG. 2;

FIG. 7 is a sectional view showing a conventional ignition coil.

FIG. 8 is a graph showing experimental results.

FIG. 9 is a perspective view schematically illustrating an arrangement relationship between a coil portion and an iron core, and a cross-sectional view taken along the line ZZ of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Coil part 10a Coil part outer surface 10b Coil part inner surface 12 Primary coil 14 Secondary coil 15 Coil case 15a Coil case outer surface 15b Shaft hole 16 Thermosetting insulating resin layer (insulating mold layer) 20 Center core part 20a Center core part outer surface 25 Non-magnetic spacer 30 Yoke part 30a Yoke part outer surface 40 Body part 50 Insulating coating part 60 Insulating filling part 70 Mounting part 71 Mounting hole 80 Integrated molding part 90 High voltage tower 91 High voltage terminal 92 High voltage protection part 100 Ignition coil 200 Spark plug 400 Ignition device C Iron core (coil core) EB Engine main body G Gap M Closed magnetic circuit S Gap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 31/00 501H 501A 501G 501L (72) Inventor Takashi Washizu 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture. F term in Japan Special Ceramics Co., Ltd. (reference) 3G019 AA02 CA08 KC02 KC03 KC04 KC05 KC06 KC10

Claims (13)

[Claims] A primary coil and a secondary coil are wound inside a coil case concentrically around an axis of the coil case.
A coil portion that accommodates a next coil and is filled with an insulating mold layer; a center core portion disposed along the axis inside the coil portion; and both end sides of the center core portion outside the coil portion And a coil core having a yoke portion that forms a closed magnetic path together with the center core portion, wherein the ignition coil is provided so that the coil core is insulated from an engine body. A mounting portion for mounting to the engine body, and an insulating filling portion that at least partially fills a gap formed between the coil portion and the coil core by facing each other, are integrally injected with a polymer material. An ignition coil characterized by being formed by molding. 2. The secondary coil is located outside the primary coil, and the insulating filling portion is formed between an outer surface of the coil portion and an inner surface of the yoke portion opposed to the coil portion. The ignition coil according to claim 1, wherein at least the gap is filled. 3. The secondary coil is located inside the primary coil, and the insulating filling portion is formed between an inner surface of the coil portion and an outer surface of the center core portion opposed to the coil portion. The ignition coil according to claim 1, wherein at least the gap is filled. 4. The ignition coil according to claim 1, wherein the insulating filling portion fills substantially the entire gap formed between the coil portion and the coil core facing the coil portion. 5. The insulating coating portion covering substantially the entire coil core is formed by integral injection molding of the polymer material together with the insulating filling portion and the mounting portion. The ignition coil according to claim 1. 6. The ignition coil according to claim 1, wherein the polymer material used for the integral injection molding is entirely made of the same material. 7. The ignition coil according to claim 1, wherein the polymer material used for the integral injection molding is made of a thermoplastic resin. 8. The ignition coil according to claim 7, wherein said thermoplastic resin used for said integral injection molding contains an insulating filler. 9. The ignition coil according to claim 8, wherein a blending ratio of the insulating filler in the thermoplastic resin is adjusted in a range of 10 to 40% by weight. 10. The thermoplastic resin has a softening point of 120.
The ignition coil according to any one of claims 7 to 9, wherein the ignition coil temperature is not lower than ℃. 11. The ignition coil according to claim 7, wherein the thermoplastic resin comprises at least one of a polybutylene terephthalate resin, a polyphenylene sulfide resin, and a polyethylene terephthalate resin. 12. The ignition coil according to claim 1, wherein the ignition coil is mounted on the engine main body, is electrically connected to the secondary coil of the ignition coil, and is generated by the ignition coil. An ignition device comprising: a spark plug that generates a spark discharge by receiving a supply of a high voltage for discharge. 13. The ignition device according to claim 12, wherein the engine is a stationary gas engine.