JP2004104005A - Ignition coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent cracks from being generated in spools and an insulation material of an ignition coil in the case of radiational cooling when linear expansion coefficients of the spools, coils and the insulation material of the ignition coil differ from each other. <P>SOLUTION: The ignition coil 10 includes: a housing 12; the secondary spool 15; the secondary coil 20 wound thereon; the primary spool 25; the primary coil 30 wound thereon; and the insulation material filled in gaps among the members as above. A buffer member 40 is placed between the primary spool 25 and the primary coil 30. The buffer member 40 is freely expanded / contracted in the axial direction and contracted in the radiational cooling of an engine and the ignition coil to permit the large contraction of the primary spool in the axial direction. Thus, the generation of cracks in flanges 27a, 27b of the primary spool can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ignition coil used in a vehicle or the like to ignite an ignition plug.
[0002]
[Prior art]
The ignition coil generally comprises a housing, a centrally located rod-shaped central core, a cylindrical secondary spool and secondary coil outside thereof, and a cylindrical primary spool and primary coil outside the housing. It comprises a cylindrical outer peripheral housing arranged on the outer periphery, and an insulating material filled in a gap between them. Since the ignition coil is inserted into the plug hole of each cylinder of the engine, when the engine is operating, its heat is transmitted and the temperature rises. When the engine is stopped, it is air-cooled (cooled). Also, since it is a kind of transformer, the primary coil and the secondary coil generate heat during operation, and are air-cooled (cooled) when not operating.
[0003]
Here, the resin which is a material of the primary spool and the secondary spool (for example, PPE (polyphenylene ether) which is a kind of thermoplastic resin) and the copper which is a material of the primary coil and the secondary coil are insulated. The material of the material (for example, epoxy resin) has a different coefficient of linear expansion. Therefore, cracks may occur in the primary spool, the secondary spool, and the insulating material.
[0004]
For example, consider a case where a primary coil is wound around the outer peripheral surface between flange portions at both ends in the axial direction of the primary spool. The insulating material (eg, epoxy resin) filled in the gap between the housing, the secondary spool and the secondary coil, the primary spool, the primary coil, and the outer core enters the gap between the primary coils and adheres to the primary spool. Further, since the linear expansion coefficient of PPE is larger than that of copper, the amount of expansion and contraction of the primary spool in the axial and radial directions during heating and cooling is larger than that of the primary coil.
[0005]
Therefore, when the engine or the like is allowed to cool, the amount of contraction of the primary spool in the axial direction is larger than that of the primary coil, so that the contraction of the primary spool is hindered by the primary coil, and as a result, cracks occur in the flange portion. easy.
[0006]
In consideration of this point, in one conventional ignition coil for an internal combustion engine, the primary spool is divided into two in the axial direction (for example, see Patent Document 1).
[0007]
[Patent Document 1]
JP-A-11-186077
In the ignition coil disclosed in Patent Document 1, as shown in FIG. 2, a primary spool 102 disposed radially inside a secondary spool 100 is divided into two in an axial direction, and each spool piece 104, Coils 106 and 109 are wound between ribs 105 and 108 provided on 107.
[0009]
In another conventional ignition coil, a peeling tape is interposed between the primary spool and the primary coil (for example, see Patent Document 2).
[0010]
[Patent Document 2]
JP-A-11-111545
In the ignition coil disclosed in Patent Document 2, as shown in FIG. 3, a separation tape 116 is interposed between a primary spool 112 and a primary coil 118 to divide the two in the radial direction. . This prevents the insulating material (not shown) from integrating the primary spool 112 and the primary coil.
[0012]
[Problems to be solved by the invention]
If the primary spool 102 is divided into two in the axial direction as in the ignition coil shown in Patent Document 1, the amount of thermal expansion and contraction of each of the spool pieces 104 and 107 is reduced, and the axial stress at both ends is reduced. Are dispersed to some extent. However, winding the primary coils 106 and 109 around the respective spool pieces 104 and 107 is not only troublesome but also increases the cost.
[0013]
Further, in the ignition coil disclosed in Patent Document 2, the separation of the primary spool 112 and the insulating material in the radial direction by interposing the peeling tape 116 between the primary spool 112 and the primary coil 118, Radial stress generated in the primary spool 112 and the insulating material is reduced. On the other hand, the primary spool 112 and the insulating material expand and contract independently in the axial direction, which is not desirable in reducing the stress in the axial direction.
[0014]
The present invention has been made in view of the above circumstances, and even when the linear expansion coefficient, that is, the thermal expansion / contraction amount of the spool, the coil, and the insulating material is different, cracks are generated in the spool and the insulating material during heating and / or cooling. It is an object of the present invention to provide an ignition coil in which noise is prevented.
[0015]
[Means for Solving the Problems]
The inventor of the present application has made the primary spool and the primary coil, the secondary spool and the secondary coil, and the primary spool and the primary coil, the secondary spool and the secondary coil without changing the material of the insulating material from the conventional one. Strategies for absorbing the difference in the amount of thermal expansion and contraction in the axial direction between the coil and the insulating material were studied. As a result, at least between the end of the primary coil and the primary spool or in the middle of the primary coil, means for absorbing the difference in thermal expansion and contraction is provided, and if necessary, the end of the secondary coil and the secondary spool are connected. The present invention has been completed with the idea that the above-mentioned means is also provided between the secondary coil and the intermediate portion of the secondary coil.
(1) The ignition coil according to the first invention of the present application is, as described in claim 1, a housing, a secondary spool wound around a secondary spool and both flange portions thereof, a primary spool and a primary spool thereof. A primary spool in an ignition coil including a primary coil wound between flange portions at both ends, a housing, a secondary spool and a secondary coil, and an insulating material filled in a gap between the primary spool and the primary coil. And a primary coil and / or a secondary spool and a secondary coil are provided with an axially expandable and contractible buffer member.
[0016]
In this ignition coil, when the engine and the ignition coil are allowed to cool, the primary spool and / or the secondary spool tend to contract more in the axial direction than the primary coil and / or the secondary coil. Then, the cushioning member contracts in the axial direction, allowing a large contraction of the first spool and / or the second spool.
[0017]
According to a second aspect of the present invention, in the first aspect, the buffer member is disposed between one end surface of the primary coil and / or the secondary coil and one of the flange portions of the primary spool and / or the secondary spool. I have.
(2) The ignition coil according to the second invention of the present application is, as described in claim 6, a housing, a secondary spool and a secondary coil wound between both flange portions thereof, a primary spool and a secondary spool thereof. In an ignition coil including a primary coil wound between both flange portions, a housing, a secondary spool and a secondary coil, an insulating material filled in a gap between the primary spool and the primary coil, the primary coil and And / or a buffer member that is axially extendable and contractible is disposed at a part of the secondary coil axial direction.
[0018]
In this ignition coil, when the engine and the ignition coil are allowed to cool, the amount of axial contraction of the primary spool and / or the secondary spool is larger than that of the primary coil and / or the secondary coil. This large contraction of the first spool and / or the secondary spool is allowed by the axial contraction of the cushioning member.
[0019]
According to a seventh aspect of the present invention, in the sixth aspect, the buffer member is disposed at an axially intermediate portion of the primary coil and / or the second coil.
(3) In the ignition coil according to the third or eighth aspect, in the first or sixth aspect, the primary spool is disposed radially outside the secondary spool. In the ignition coil according to the fourth or ninth aspect, in the first or sixth aspect, the cushioning member is made of rubber, elastomer, or sponge. In the ignition coil according to the fifth or tenth aspect, the peeling tape is interposed between the primary spool and the primary coil in the first or sixth aspect.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
The ignition coil according to the first and second inventions is a housing, a primary coil wound around an outer peripheral surface between a primary spool and a flange thereof, a secondary coil wound around an outer peripheral surface between a secondary spool and a flange thereof, Including an insulating material and a cushioning member. Further, it may include an inner core, a release tape, an outer core, and the like.
<Housing, center core, outer core>
The housing is made of resin and has a cylindrical shape, and holds a central core, a primary spool and a secondary spool, an outer core, and the like. The central core is made of steel, has a round bar shape, and is disposed at the center of the housing. The outer peripheral core is made of steel and has a cylindrical shape, and is disposed further outside the spool and the coil located radially outward. <Primary spool, primary coil, secondary spool, secondary coil>
The primary spool is made of resin and has a cylindrical shape. A pair of annular flange portions are provided at both ends (uppermost end and lowermost end) or at portions that are slightly retracted toward the middle from both ends.
[0021]
The secondary spool has the same configuration as the first spool except for the inner diameter and the outer diameter, and is arranged concentrically with the first spool. The fact that the primary spool has a larger radius than the secondary spool, that is, disposing the primary spool radially outside the secondary spool, improves the high voltage resistance by reducing the electric field strength at the outer periphery of the coil. Desirable above. However, the primary spool can be arranged radially inside the secondary spool.
[0022]
The wire diameter of the primary coil wound on the outer peripheral surface of the primary spool is larger than that of the secondary coil wound on the outer peripheral surface of the secondary spool, and the number of turns is smaller than that of the secondary coil. One end of the primary coil is connected to a power supply, and the other end is connected to a current breaker such as an igniter. One end of the secondary coil is connected to the primary coil, and the other end is connected to the ignition plug.
[0023]
The gap between each member is filled with an insulating material. A release tape can be interposed between the primary spool and the primary coil. The release tape is made of silicon or the like, and separates the primary spool from the primary coil and the insulating material in the radial direction.
<Buffer member>
"Disposing the cushioning member between the primary spool and the primary coil" means "between one end face of the primary coil and one flange portion of the primary spool, and both end faces and both of the primary spool. Including between the flange part. The term "arranged in a part in the axial direction" may be any arrangement in the middle of the primary coil, and includes the vicinity of one end, the vicinity of the other end, and the middle part. The number of buffer members may be one, or two or more.
[0024]
The same applies to the buffer member disposed between the secondary spool and the secondary coil or in the middle of the secondary coil.
[0025]
The buffer member absorbs a difference in the amount of thermal expansion and contraction in the axial direction between the primary spool, the primary coil, and the insulating material. It is made of a material such as rubber (silicon, acrylic, etc.), elastomer, sponge (silicon, etc.) and can have a ring shape or a cylindrical shape. The above situation is the same also about the buffer member arrange | positioned at a secondary spool and a secondary coil.
[0026]
The cushioning member is disposed at least between the end of the primary coil and the flange of the primary spool or at an intermediate portion of the primary coil, whereby the peeling tape is interposed between the primary spool and the primary coil. Also in this case, the stress in the axial direction can be reduced. It should be noted that a buffer member can be arranged on the secondary spool and the secondary coil as needed.
[0027]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this embodiment, a release tape is interposed between the primary spool and the primary coil, and the cushioning member is disposed between one end (upper end) of the primary coil and one (upper end) flange of the first spool. Have been.
(Constitution)
In FIG. 1, an ignition coil 10 includes a housing 12, a central core 14 arranged radially outward from a center in an inner space of the housing 12, a secondary spool 15, a secondary coil 20, a primary spool 25, and a primary coil. 30 and an outer peripheral core 35. The housing 12 is made of polyphenylene sulfide (PPT), has a cylindrical shape, and supports the upper and lower ends of the secondary spool 15 and the primary spool 25. The central core 14 is formed by laminating thin silicon steel plates, has a cylindrical shape, and is positioned on the inner wall of the secondary spool 15.
[0028]
The secondary spool 15 is a bobbin for forming the secondary coil 20, is made of resin, and has a cylindrical shape as a whole. It has a main body 16 and flanges 17 at both upper and lower ends thereof. The flange 17 is positioned by the primary spool 25. The secondary coil 20 is formed of a very thin coil wire which is wound around the outer peripheral surface of the secondary spool 15 in a cylindrical shape and coated with insulation.
[0029]
A primary spool 25 located radially outside the secondary spool 15 is a bobbin for forming a primary coil 30 and is made of resin and has a cylindrical shape as a whole. It has a main body 26 and flange portions 27a, 27b at both upper and lower ends thereof, and is supported by the outer peripheral core 35 and the housing 12 at the flange portions 27a, 27b.
[0030]
The primary coil 30 is formed of a coil wire wound around the outer peripheral surface of the primary spool 25 and coated with insulation, and is thicker than the coil wire of the secondary coil 20. The axial length of the primary coil 30 is shorter than the distance between the flange portions 27a and 27b of the primary spool 25, and the cushioning member 40 is provided between the upper end surface of the primary coil 30 and the upper flange portion 27a. It is interposed.
[0031]
The buffer member 40 is made of rubber and has a ring shape. The inner and outer diameters are substantially equal to the inner and outer diameters of the primary coil 30, respectively. The length is equal to or greater than the difference between the amount of axial contraction of the primary spool 25 and that of the primary coil 30.
[0032]
A release tape 32 made of silicon is interposed between the primary spool 25 and the primary coil 30. The outer core 35 is formed by winding a thin silicon steel sheet. A gap between the housing 12, the central core 14, the secondary spool 15, the secondary coil 20, the primary spool 25 and the primary coil 30, the buffer member 40, and the like is filled with an insulating material (not shown) made of epoxy resin. ing. The insulating material is obtained by assembling the center core 14, the secondary spool 15, the primary spool 25, the cushioning member 40, and the like in the housing 10, and then vacuum-filling these gaps. The members are electrically insulated from each other, and the members are fixed to prevent damage due to vibration.
[0033]
The ignition coil 10 is mounted in a plug hole formed for each cylinder of an engine (not shown), a lower end thereof is connected to an ignition plug, and a connector is connected to an upper end thereof. More specifically, the connector 50 mounted on the upper end of the housing 12 projects upward from the plug hole, and an input terminal 52 for supplying an ignition signal to the primary coil 30 is insert-molded. This input terminal 52 is supplied with an ignition signal from a control circuit (not shown).
[0034]
A high-voltage terminal 55 is mounted on the lower end of the housing 12. The high-voltage terminal 55 is insert-molded in the housing 12 and is electrically connected to the spring 56. The spring 56 is electrically connected to the ignition plug when the ignition coil 10 is mounted in the plug hole, and the high voltage generated by the secondary coil 20 is applied to the ignition plug (not shown) via the high voltage terminal 55 and the spring 56. Applied. A rubber plug cap 58 is attached to the lower end opening of the high-voltage terminal 55.
[0035]
The ignition coil device 60 includes the ignition coil 10, the connector 50, the high-voltage terminal 55, and the like.
(Effect)
In the ignition coil device 60, the primary current of the primary coil 30 is intermittently controlled based on the ignition signal from the control circuit. As a result, the voltage of the power supply (not shown) is boosted to a high voltage for ignition in the secondary coil 20, and a spark is generated between the electrodes of the spark plug. According to this embodiment, the following effects can be obtained.
[0036]
First, the occurrence of cracks in the flange portions 27a and 27b of the primary spool 25 due to the stress in the axial direction is prevented. The primary spool 25 is heated when the engine and the ignition coil 10 are operated, and is cooled when not operating. The amount of axial contraction of the primary spool 25 during cooling is greater than that of the primary coil 30.
[0037]
However, a buffer member 40 is interposed between the upper end surface of the primary coil 30 and the flange portion 27a above the primary spool 25. The cushioning member 40 contracts at the time of cooling, allowing the primary spool 25 to contract more than the primary coil 30 contracts. As a result, the axial outward force acting on the primary spool 25 from the primary coil 30 is reduced, and the occurrence of cracks on the flange portions 27a and 27b is prevented.
[0038]
Secondly, the occurrence of cracks in the primary spool 25 and a part of the insulating material due to circumferential stress is prevented. The amount of contraction of the primary spool 25 in the radial direction during cooling is greater than that of the primary coil 30 and the insulating material. However, the reason is that the primary spool 25 is separated from the primary coil 30 and the insulating material by the peeling tape 32 in the radial direction.
[0039]
The primary spool 25, the primary coil 30, and the insulating material are likely to contract independently in the axial direction due to the interposition of the release tape 32. However, as described above, the buffer member 40 interposed between the upper end of the primary coil 30 and the flange portion 27a absorbs the difference in the amount of contraction.
[0040]
【The invention's effect】
As described above, according to the ignition coil of the first invention and the second invention, when the engine and the ignition coil are allowed to cool, the primary spool is larger than the axial contraction of the primary coil and / or the secondary coil. And / or axial contraction of the secondary spool is allowed by contraction of the cushioning member. As a result, the occurrence of cracks in the flange portions of the primary spool and / or the secondary spool due to the stress in the axial direction is prevented, and the ignition coil can exhibit a predetermined function for a long period of time.
[0041]
According to the ignition coil of the second aspect, the arrangement of the windings of the primary coil and / or the secondary coil and the buffer member is simplified. According to the ignition coil of the seventh aspect, the buffer member can be arranged at the intermediate portion between the primary coil and / or the secondary coil, and the flexibility of arrangement is improved.
[0042]
According to the ignition coil of the third and eighth aspects, the occurrence of cracks in the flange portion is prevented in the secondary spool located radially inward and / or the primary spool located radially outward or the insulating material. According to the ignition coil of the fourth and ninth aspects, a shock-absorbing member with high contractility can be realized at low cost.
[0043]
According to the ignition coil of the fifth and tenth aspects, generation of cracks in the primary spool and the insulating material due to radial stress is more effectively prevented.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view (an intermediate portion is omitted) showing an embodiment of an ignition coil of the present invention.
FIG. 2 is a sectional view of a main part showing a first conventional example.
FIG. 3 is a sectional view of a main part showing a second conventional example.
10: ignition coil 12: housing 14: center core 15: secondary spool 20: secondary coil 25: primary spool 27a: flange portion 30: primary coil 32: peeling tape 35: outer peripheral core

Claims (10)

A housing, a secondary spool and a secondary coil wound between both flange portions of the secondary spool, a primary spool and a primary coil wound between both flange portions of the primary spool, and the housing; An ignition coil including: the secondary spool and the secondary coil; an insulating material filled in a gap between the primary spool and the primary coil;
An ignition coil characterized in that an axially expandable and contractible buffer member is disposed between the primary spool and the primary coil and / or between the secondary spool and the secondary coil. The buffer member is disposed between one end surface of the primary coil and one flange portion of the primary spool and / or between one end surface of the secondary coil and one flange portion of the secondary spool. The ignition coil according to claim 1, wherein the ignition coil is provided. The ignition coil according to claim 1, wherein the primary spool is disposed radially outward of the secondary spool. The ignition coil according to claim 1, wherein the buffer member is made of rubber, elastomer, or sponge. The ignition coil according to claim 1, wherein a release tape is interposed between the primary spool and the primary coil. A housing, a secondary spool and a secondary coil wound between both flange portions of the secondary spool, a primary spool and a primary coil wound between both flange portions of the primary spool, and the housing; An ignition coil including: the secondary spool and the secondary coil; an insulating material filled in a gap between the primary spool and the primary coil;
An ignition coil, wherein a buffer member that is axially expandable and contractable is disposed at a part of the primary coil in the axial direction and / or at a part of the secondary coil in the axial direction. The ignition coil according to claim 6, wherein the buffer member is disposed at an axial middle portion of the primary coil and / or an axial middle portion of the secondary coil. The ignition coil according to claim 6, wherein the primary spool is disposed radially outside the secondary spool. The ignition coil according to claim 6, wherein the buffer member is made of rubber, elastomer, or sponge. The ignition coil according to claim 6, wherein a release tape is interposed between the primary spool and the primary coil.

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