JP3561121B2 - Ignition coil for internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an independent ignition type ignition coil for an internal combustion engine which is prepared for each spark plug of an engine and is used directly connected to each spark plug.
[0002]
[Prior art]
In recent years, an independent ignition type ignition coil for an internal combustion engine which is introduced into a plug hole of an engine and directly connected to each ignition plug has been developed. This type of ignition coil device does not require a distributor, and as a result, the energy supplied to the ignition coil does not drop due to the distributor, its high-voltage cord, and the like, and further, there is no consideration that the ignition energy drops. The design of the ignition coil has been evaluated as being able to reduce the coil volume, reduce the size of the ignition coil, and streamline the component mounting space in the engine room by eliminating the distributor.
[0003]
Such an independent ignition type ignition coil is called a plug hole mounting type because at least a part of the coil portion is introduced and mounted in the plug hole, and also because the coil portion is inserted into the plug hole. It is generally referred to as a pencil coil which is elongated in a pencil shape, and includes a center core (in which a number of silicon steel plates are laminated with a magnetic core), a primary coil, and a secondary coil inside an elongated cylindrical coil case. The primary and secondary coils are wound around respective bobbins and are arranged concentrically around the center core. Insulation thermosetting resin is injected and hardened in the coil case for accommodating such primary and secondary coils, or insulating oil is sealed therein to assure the insulation of the coil.
[0004]
Known examples include, for example, JP-A-8-255719, JP-A-9-7860, JP-A-9-17662, JP-A-9-167709, JP-A-8-93616, and JP-A-8-93616. JP-A-97057, JP-A-8-144916, JP-A-8-203775 and the like.
[0005]
Among these conventional examples, for example, as described in Japanese Patent Application Laid-Open No. 9-167709 (Japanese Patent Application No. 7-326800), a center core formed by laminating silicon steel sheets in order from the inside of a coil case, a secondary core, A secondary coil wound on a bobbin and a primary coil wound on a primary bobbin are concentrically mounted, and a thermosetting resin (such as an epoxy resin) for insulation is provided around these components (between the components). ).
[0006]
In this conventional example, since the secondary coil is disposed inside and the primary coil is disposed outside, it may be referred to as an inner secondary coil structure.
[0007]
The so-called pencil coil (independent ignition type ignition coil for an internal combustion engine) has a so-called outer secondary coil structure in which a primary coil is disposed inside and a secondary coil is disposed outside, and an inner secondary coil as described above. The inner secondary coil structure has an advantage in output characteristics as described below, as compared with the outer secondary coil structure.
[0008]
Assuming a pencil coil in which an insulating resin (for example, epoxy resin) is injected and cured (filled) between components of the coil, as shown in FIG. 7, in the outer secondary coil structure, a primary coil and an epoxy There are resin, secondary bobbin, secondary coil, epoxy resin, coil case, and side core. Electrostatic stray capacitance between the secondary coil and the low-voltage primary coil (which can be regarded as almost ground voltage) inside it. In addition to the above, an electrostatic stray capacitance is also generated between the secondary coil and the side core (ground voltage). Therefore, the electrostatic stray capacitance on the side core side is extra compared with the inner secondary coil structure, and the outer secondary The electrostatic stray capacitance of the coil structure tends to increase. On the other hand, in the case of the inner secondary coil structure, an electrostatic stray capacitance is generated between the secondary coil and the primary coil, and between the primary coil and the side core, the electrostatic stray capacitance is substantially generated because both the primary coil and the side core are at the ground voltage. Absent.
[0009]
The secondary voltage output and its rise characteristics are affected by the electrostatic stray capacitance. As the electrostatic stray capacitance increases, the output decreases and the rise is delayed. Therefore, it is considered that an inner secondary coil structure having a small electrostatic stray capacitance is more suitable for miniaturization and high output.
[0010]
In addition, of the independent ignition type ignition coils for internal combustion engines, those in which an insulating resin (for example, epoxy resin) is injected and cured in the coil case eliminates the need for oil sealing (sealing) measures as in the insulating oil type. Also, since the components such as the center core, bobbin, coil, etc. can be fixed by simply embedding them in the insulating resin, the fixing of these components is simpler than in the case of the insulating oil system, and the simplification of the entire apparatus and the handling of the device are simplified. It is evaluated as being easy to use.
[0011]
Various thermoplastic resins have been proposed as materials for the primary bobbin and the secondary bobbin. For example, in the inner secondary coil structure as disclosed in Japanese Patent Application Laid-Open No. 9-167709, the A material using modified PPO (modified polyphenylene oxide) having a good affinity for an epoxy resin has been proposed as a material, and polybutylene terephthalate (PBT) is used as a primary bobbin. Japanese Patent Application Laid-Open No. Hei 9-17662 (Japanese Patent Application No. 7-165141) discloses an outer secondary coil structure (inner primary coil structure) in which a bobbin (primary bobbin) of the primary coil is formed of PBT or PPS (polyphenylene sulfide). ) And using a modified PPO as the secondary bobbin.
[0012]
[Problems to be solved by the invention]
In the ignition coil for an internal combustion engine of this kind of independent ignition type, in the case of the above-mentioned inner secondary coil structure and the insulating resin injection hardening method in the coil case, there are various advantages as described above, but the secondary bobbin and the It is important to make the ignition coil device more compact while ensuring the thermal shock resistance (reduction of electric field concentration) and insulation performance around the center core and the secondary coil.
[0013]
In other words, in the case of a system in which a center core, a secondary coil, and a primary coil are sequentially provided inside a coil case (so-called inner secondary coil structure), the secondary coil having a potential difference and the center core, and the secondary coil and the primary coil When a crack (gap) due to thermal shock occurs in the insulating resin between the coils, so-called electric field concentration in which the electric field intensity in the gap becomes extremely large occurs, and dielectric breakdown occurs. In particular, in the inner secondary coil structure, the thermal shock between the center core and the secondary coil and the secondary bobbin, which occupies the largest proportion of the volume, increases, and there is a concern that cracks may occur in the insulating resin therebetween. .
[0014]
Conventionally, modified PPO has been used as a secondary bobbin because of its good affinity with injected thermosetting resin such as epoxy resin.
[0015]
The present inventors have experimentally examined the coefficient of linear expansion of the secondary bobbin formed of the modified PPO. As a result, especially in the case of the inner secondary coil structure, the difference in the coefficient of linear expansion between the center core and the secondary coil was 2%. More than twice as large, the thermal shock was increased, and it was found that the thermal shock should be improved.
[0016]
That is, the coefficient of linear expansion of the thermoplastic resin used as the bobbin material changes depending on the temperature. In the case of the modified PPO, the coefficient of linear expansion was examined in the range of room temperature (20 ° C.) to 150 ° C. If the linear expansion coefficient in the temperature range is expressed as a total, 25 to 80 × 10 ° including the flow direction (flow) and the right angle direction (crossflow) during molding.⁶(In other words, 25 to 80 × 10E-6) was obtained.
[0017]
On the other hand, the linear expansion coefficient of the center core made of a silicon steel sheet is 13 × 10 °⁶It is. The coefficient of linear expansion of the secondary bobbin made of the modified PPO is more than twice the coefficient of linear expansion of the center core (the same can be said for a copper wire as a coil). When a thermal stress of up to 130 ° C. is applied, the thermal strain increases, and there is a high probability that cracks occur in the insulating resin filled between the center core and the secondary bobbin and around the secondary coil.
[0018]
The present invention has been made in view of the above points, and an object of the present invention is to provide an ignition coil for an internal combustion engine of this type of independent ignition type, particularly in an inner secondary coil structure and an insulated resin injection hardening method in a coil case. In addition to improving the thermal shock resistance and insulation performance between the center core and the secondary bobbin and between the ignition coil components such as the secondary bobbin and the secondary coil, which were the most important issues in terms of insulation performance, It is an object of the present invention to provide an ignition coil that can respond to the demands for conversion.
[0019]
The present inventionBasically, the configuration is as follows.
That is,An elongated center core serving as a magnetic circuit of an ignition coil is held in a bottomed cylindrical secondary bobbin around which a secondary coil is wound, and a cylindrical primary bobbin around which a primary coil is wound outside the secondary bobbin. Are disposed in an elongated cylindrical coil case, and an igniter case for storing an ignition circuit unit is provided at one end of the cylindrical coil case, and the ignition circuit unit includes the secondary bobbin. An ignition coil for an internal combustion engine, which is disposed on a surface of one end opening through a base holding the ignition circuit unit,
A magnet and a rubber are arranged so as to overlap between one end of the center core and the bottom of the secondary bobbin, and another magnet is arranged at the other end of the center core. Covered with a thin elastic insulating layer consisting of soft epoxy, silicone rubber, or silicone gel,
The coil case and the igniter case are filled with an insulating resin harder than the elastic insulating layer and solidified to hold between the coil case and the primary coil, between the primary bobbin and the secondary coil, and the ignition circuit unit. The hard insulating resin is filled between the base and the elastic insulating layer.
In addition, the following invention is proposed.
[0020]
(A) In an ignition coil for an internal combustion engine of an independent ignition type used directly connected to each ignition plug of the engine,
A center core, a secondary coil wound around a secondary bobbin, and a primary coil wound around a primary bobbin are concentrically housed in the coil case in order from the inside, and the secondary bobbin has a modified PPO (modified polyphenylene oxide) having a linear expansion coefficient of ) And a material closer to the center core than copper material.
[0021]
(B) Further, as such a secondary bobbin, a secondary bobbin that is made of PPS (polyphenylene sulfide) or a mixed material of PPS and another resin is proposed.
[0022]
For example, a secondary bobbin is made of a material in which PPS is mixed with glass fiber and an inorganic powder such as talc in a total amount of 50 to 70% by weight, or a material in which PPS is mixed with quartz powder and molten glass powder in a total amount of 50 to 70% by weight. It is composed of materials.
[0023]
(C) According to the secondary bobbin configured as described above, the linear expansion coefficient in the range of room temperature (20 ° C.) to 150 ° C. is 10 to 45 × 10 ° including the flow direction and the perpendicular direction at the time of molding.⁶(In other words, those in the range of 10 to 45 × 10E-6) were obtained.
[0024]
(D) With the configuration described above, the thermal shock resistance can be increased as compared with the conventional secondary bobbin material. In particular, when the secondary bobbin is made of PPS, the secondary bobbin is set to about の of the linear expansion coefficient of the modified PPO, and the secondary bobbin is made to have a center core (silicon steel plate) or a coil material (copper wire) more than ever. ) Close to the linear expansion coefficient.
[0025]
According to the experiments of the present inventors, the thermal shock test in which the secondary bobbin is made of PPS and the inorganic powder is mixed in a total of 50 to 70%, in which -40 ° C. and 130 ° C. are alternately repeated, is 300 cycles or more. Even if it was repeated, it was confirmed that no crack occurred in the insulating resin (epoxy resin) between the center core and the secondary bobbin and between the secondary bobbin and the secondary coil. On the other hand, a similar test was performed on a secondary bobbin made of modified PPO, and as a result, cracks were observed.
[0026]
(E) As a result, the present inventors have found that the secondary bobbin has a linear expansion coefficient in the range of 20 ° C. to 150 ° C. at the time of molding in the inner secondary coil / coil case insulating resin injection hardening method. 10 to 45 × 10￣ including the flow direction and the perpendicular direction⁶In order to satisfy the required thermal shock resistance as long as the material falls within the range described above, the present invention has been established for an ignition coil for an internal combustion engine having a secondary bobbin made of a material satisfying such a linear expansion coefficient.
[0027]
(F) Further, in the inner secondary coil structure, a potential difference is generated between the secondary coil and the center core (the potential difference is about 15 V, and a mechanism for generating the potential difference will be described later). However, when the secondary bobbin is made of PPS, PPS is superior to modified PPO in insulation performance and mechanical strength. On the other hand, the thickness can be reduced to half of that of the modified PPO, the thickness of the secondary bobbin can be reduced by the PPS, and the diameter of the secondary bobbin can be reduced, and the size of the ignition coil device can be reduced. That is, when the insulation performance between PPS and modified PPO is compared, PPS has a withstand voltage (breakdown voltage) of 20 kv / mm at normal temperature (20 ° C.), modified PPO has a breakdown voltage of 16 to 20 kv / mm, and PPS has a modified voltage. Since the Young's modulus can be made twice as large as that of the modified PPO by the blending ratio of the inorganic powder as compared with the PPO, the wall thickness can be reduced to half of that of the modified PPO with respect to both requirements of insulation performance and mechanical strength. .
[0028]
(G) Incidentally, Japanese Patent Application Laid-Open No. Hei 9-17662 (Japanese Patent Application No. Hei 7-165141) discloses a conventional secondary coil structure (inner primary coil structure) and a bobbin (primary bobbin) of the primary coil. Although it is suggested that PPS (polyphenylene sulfide) is used, this uses PPS for the primary bobbin of the outer secondary coil structure (inner primary coil structure). The problem of the structure and the insulating resin injection hardening method in the coil case cannot be solved.
[0029]
(H) In addition to the above-described configuration, the present invention provides a secondary bobbin in which the secondary bobbin is a mixed material of PPS and another resin,
In addition to the secondary bobbin being made of PPS or a mixed material of PPS and another resin, in addition to this, a thermosetting resin filled between the secondary bobbin and the center core may be [the secondary bobbin allowable. Stress> (resin having a glass transition point Tg that satisfies the condition of stress> (-40 ° C.−stress generated at the secondary bobbin at the glass transition point Tg of the insulating resin)), and the secondary bobbin and the center core. Has a glass transition point of at least 20 ° C. or lower, and has a Young's modulus of 1 × 10 at or above the glass transition point.⁸(Pa) the following flexible epoxy resin,
It is suggested that the thermosetting resin filled between the secondary bobbin and the center core is made of a resin substantially equivalent to the relative permittivity of the secondary bobbin. Will be described in [Embodiment].
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0031]
First, an ignition coil device according to a first embodiment will be described with reference to FIGS.
[0032]
FIG. 1 shows a longitudinal sectional view (a sectional view taken along the line BB 'in FIG. 3) of the ignition coil device 21 and an enlarged sectional view of a portion E of a part thereof, and FIG. 2 shows AA' in FIG. FIG. FIG. 3 is a view of the ignition coil device of FIG. 1 as viewed from above, and shows the inside of the circuit case 9 before filling with resin (silicon gel).
[0033]
Inside the elongated cylindrical coil case (exterior case) 6, a center core 1, a secondary bobbin 2, a secondary coil 3, a primary bobbin 4, and a primary coil 5 are arranged in order from the center (inside) to the outside. You.
[0034]
As shown in FIG. 2, for example, as shown in FIG. 2, a large number of silicon steel plates or directional silicon steel plates of about 0.3 to 0.5 mm whose width is set in several stages are pressed to increase the cross-sectional area of the center core 1. It is laminated and inserted into the inner diameter of the secondary bobbin 2.
[0035]
The secondary bobbin 2 is disposed between the center core 1 and the secondary coil 3 and also has a role of insulating high voltage generated in the secondary coil 3. The material of the secondary bobbin 2 is PPS and is a thermoplastic resin. The secondary coil 3 wound around the secondary bobbin 2 is divided into a total of about 10,000 to 30,000 times using an enamel wire having a wire diameter of about 0.03 to 0.06 mm. The outer diameter of the secondary bobbin 2 around which the secondary coil 3 is wound is formed smaller than the inner diameter of the primary bobbin 4, and the secondary bobbin 2 and the secondary coil 3 are located inside the primary bobbin 4. Since PPS is used for the secondary bobbin 2, the secondary bobbin can be made thinner and the wall thickness can be reduced to 0.5 to 1.2 mm as described in [Means for Solving the Problems]. . In addition, glass fiber and inorganic powder such as talc are mixed in an amount of 50 to 70% by weight or more to minimize the difference in linear expansion coefficient from the metal in the coil case 6. This will be described later. Among the thermoplastic synthetic resins, PPS has better fluidity at the time of molding than modified PPO and PBT, and therefore has a feature that the fluidity is not impaired even when the amount of the inorganic powder is 50% to 70% by weight.
[0036]
The primary bobbin 4 is also formed of the same PPS as the secondary bobbin 2, and has a primary coil 5 wound thereon. When PPS is adopted, as described above, molding with a thin wall is possible, and the thickness of the primary bobbin 4 is about 0.5 mm to 1.2 mm. In addition, glass fiber and inorganic powder such as talc are mixed in an amount of 50 to 70% by weight or more to minimize the difference in linear expansion coefficient between the metal and the metal in the coil. The primary bobbin 4 may be formed of modified PPO. Regardless of whether the bobbin material is made of PPS or modified PPO, it is better to use a material having a heat deformation temperature of 150 ° C. or more in consideration of the fact that the present ignition coil is mounted in the plug hole. PPS mixed with 50 to 70% of inorganic powder selected as a material for the primary bobbin 4 and the secondary bobbin 2 has a tensile strength of about 1.5 / and a linear expansion coefficient of 1/2 as compared with the conventional modified PPO. Therefore, cracking can be improved about three times.
[0037]
The primary coil 5 is wound around an enameled wire having a wire diameter of about 0.3 to 1.0 mm, several tens of times per layer, several layers and a total of about 100 to 300 times. In addition, in the enlarged sectional view of the part E in FIG. 1, the primary coil 5 is schematically represented by one layer for convenience of drawing, but is actually composed of several layers as described above.
[0038]
The number of steps in the spool area for split winding of the secondary coil 3 set by the flange 2B of the secondary bobbin 2 is in the range of 12 to 14. In the case where the output voltage of the secondary coil 3 is 25 to 40 kV, the maximum voltage difference between the low voltage and the high voltage is 25 to 40 kV as described above unless there is a division winding. If the coils are wound close to each other (winding collapse or the like), the breakdown voltage may exceed the line breakdown voltage and cause dielectric breakdown. In this example, in order to cope with such a situation, the secondary coil 3 is dividedly wound to reduce the line voltage in each spool area, and a pencil coil (ignition coil device) is used in the inner secondary coil structure. Based on the conclusion of (2) that the line withstand voltage, which can be reduced in each spool area, should be as small as possible, about 2-3V in consideration of the restrictions on the diameter and the axial direction when mounting in the plug hole. It is preferable that the number of steps of the spool area is set in the range of 12 to 14, and such a setting is made.
[0039]
The protrusion amount of the secondary bobbin flange 2B, that is, the distance from the secondary coil outer diameter to the secondary bobbin flange outer diameter is in the range of 0.1 to 0.4 mm, and the thickness of the secondary bobbin flange is 0 mm. 0.6 to 1.0 mm. The above-mentioned dimension of the amount of protrusion of the secondary bobbin flange 2B is such that the wire diameter of the secondary coil (maximum used diameter of 0.03 to 0.03 mm) is ensured by taking into account the dimensional tolerance of the amount of protrusion while securing the anchoring effect on the epoxy resin 8 by protrusion. 0.1 mm) is a result of consideration to prevent the wire of the secondary coil from crossing the flange.
[0040]
The above-mentioned thickness of the secondary bobbin flange 2B is also adopted as an optimum value in order to reduce the total length of the pencil coil and to improve the adhesive strength to the epoxy resin 8 on the secondary bobbin flange 2B. .
[0041]
In order to increase the area occupied by the center core 1 and increase the output as much as possible under the restriction of downsizing (smaller diameter) of the ignition coil device, it is necessary to select a resin that can be formed into a thin bobbin material. However, as described above, PPS has a good fluidity at the time of molding among thermoplastic synthetic resins, and is advantageous for thinning without impairing fluidity even when the blending amount of the inorganic powder is 50% by weight or more. There are features. When PPS is used for the secondary bobbin 2, glass fiber and inorganic powder such as talc are mixed in an amount of 50 to 70% by weight in order to make the difference in linear expansion coefficient between the coil part and the metal as close as possible. The linear expansion coefficient in the range of room temperature (20 ° C.) to 150 ° C. is 10 to 45 × 10 °, including the flow direction and the right angle direction during molding.⁶Range.
[0042]
When the PPS having the above composition is used, the Young's modulus of the secondary bobbin 2 is twice as large as that of the modified PPO. The thickness of the bobbin can be reduced.
[0043]
A thermosetting resin for insulation is injected around the components of the ignition coil, and a so-called soft epoxy resin (flexible epoxy) 17 is provided in a gap between the center core 1 and the secondary bobbin 2. The epoxy resin 8 is filled in the gaps between the constituent members of the secondary bobbin 2, the secondary coil 3, the primary bobbin 4, the primary coil 5, and the coil case 6 which are filled.
[0044]
If the soft epoxy resin 17 is defined here, it is an epoxy resin having a glass transition point of room temperature (20 ° C.) or lower and an elastic soft property above the glass transition point (for example, the Young's modulus is 1 × above the glass transition point). 10⁸The composition is a mixture of an epoxy resin and a modified aliphatic polyamine (mixing ratio is, for example, 1: 1, 100 parts by weight of an epoxy resin and 100 parts by weight of a modified aliphatic polyamine).
[0045]
The reason why the insulating resin between the center core 1 and the secondary bobbin 2 is made of the soft epoxy resin 17 is that the independent ignition type ignition coil device (pencil coil) mounted in the plug hole has a severe temperature environment (-40 ° C. to 130 ° C.). C.) and the thermal expansion coefficient of the center core 1 (13 × 10 ° C.).⁶mm / ° C.) and the coefficient of thermal expansion of the epoxy resin (40 × 10 °)⁶(mm / ° C.), cracks occur in the epoxy resin due to heat shock when a normal insulating epoxy resin (an epoxy resin composition harder than the soft epoxy 17) is used. This is because dielectric breakdown may occur. That is, in order to cope with such a heat shock, a soft epoxy resin 17 having an insulating property and made of an elastic material excellent in thermal shock absorption is used.
[0046]
The casting process of the soft epoxy resin 17 is as follows.
[0047]
For example, after inserting the center core 1 into the secondary bobbin 2, these are placed in a vacuum chamber and the chamber is evacuated (for example, 4 Torr). In the meantime, the soft epoxy resin 17 is injected and filled in a liquid state, and then heated and cured in air at 120 ° C. for 1.5 to 2 hours.
[0048]
By having such a step, the soft epoxy resin 17 injected in a vacuum state is placed under the atmospheric pressure at the time of heating and curing, so that the soft epoxy resin 17 between the secondary bobbin 2 and the center core 1 is heated and cured. Pressure molding (compression molding) is performed by the differential pressure between atmospheric pressure and vacuum pressure.
[0049]
By molding the soft epoxy resin 17 under pressure, the volume of voids contained in the resin can be reduced to 1/200, and further voidlessing can be achieved. The size of the void where no discharge occurs is 0.05 mm or less when the insulating layer between the discharge electrodes is 1.0 mm, and it is necessary to reduce the size of the void that does not generate the above-described discharge as the insulating layer becomes thinner. Yes, pressure molding is effective in that sense.
[0050]
FIG. 6 is a view showing only the secondary bobbin 2 filled with the soft epoxy 17 out of the above-mentioned coil elements and showing the inside thereof in a longitudinal cross section (in FIG. 6, between the center core 1 and the secondary bobbin 2). Is exaggerated for the sake of drawing convenience to clarify the features).
[0051]
As shown in FIG. 6, the soft epoxy resin 17 filled in the secondary bobbin 2 is filled from the space between the center core 1 and the secondary bobbin 2 to the upper end opening of the secondary bobbin 2 in more detail. When the pressure molding is performed using the differential pressure between the atmospheric pressure and the vacuum pressure, a mortar-shaped (hemispherical) curved concave 17 ′ is formed on the surface of the soft epoxy resin at the opening position of the upper end of the secondary bobbin 2 by pressure molding. (The depth is, for example, about 3 to 5 mm). The recess 17 ′ is formed by recessing the center of the opening end of the secondary bobbin 2, and the periphery thereof is formed in a mortar shape by maintaining a substantially unchanged state due to surface tension.
[0052]
By individually filling the soft epoxy resin 17 only in the secondary bobbin 2, a recess 17 ′ is formed on the surface of the resin 17 on the opening side of the secondary bobbin. 1, a pressing force concentrated in the axial direction acts to effectively suppress magnetic vibrations and the like generated in the center core 1 made of laminated steel sheets, and further improve vibration resistance. However, if the recess 17 'is left as it is, the center core 1 and the metal base 37 in the ignition circuit case 9 will not be connected when the ignition circuit case 9 (see FIG. 1) is arranged above the coil case (upper coil portion). Gaps are left between them, causing the following inconvenience.
[0053]
When the center core 1 is insulated, the center core is considered to have an intermediate potential of the secondary coil 3 as shown in FIG. 8 (for example, when the secondary coil generation voltage is about 30 kV, the center core has the intermediate potential of 15 kV). ). On the other hand, since the metal base 37 of the circuit located above the center core 1 is grounded, if there is a gap between the center core 1 and the metal base 37, electric field concentration occurs and dielectric breakdown occurs.
[0054]
In the present embodiment, the recesses (voids) 17 ′ generated by the pressure molding of the soft epoxy resin 17 are filled with the epoxy resin 8 having a higher insulating property than the soft epoxy resin. Insulation between the core 1 and the metal base 37 is guaranteed.
[0055]
In particular, since the recess 17 ′ formed on the upper surface of the insulating resin 17 has a hemispherical shape, no corner exists in the recess 17 ′ filled with the epoxy resin (molding resin) 8. Even if the recess 17 ′ is filled with the molding resin 8, voids are unlikely to remain, and good adhesion between the soft epoxy resin 17 at the recess interface and the epoxy resin injected thereon can be maintained. The interface between the epoxy resin 8 and the soft epoxy resin 17 (hemispherical curved concave surface 17 ′) has good adhesiveness because both are epoxy-based.
[0056]
Incidentally, the insulation performance (breakdown voltage) of the soft epoxy resin 17 used in this example changes with temperature (the insulation performance decreases as the temperature rises), but is 10 to 16 kV / mm, and the epoxy resin 8 is 16 to 20 kV / mm. mm.
[0057]
The soft epoxy resin 17 has the following formula: [Allowable stress σ of secondary bobbin 2₀> (-40 ° C.-Glass transition temperature Tg of soft epoxy resin 17)]. Here, as an example, the soft epoxy resin 17 having a glass transition point Tg of −25 ° C. is exemplified.
[0058]
For example, when the glass transition point of the soft epoxy resin 17 is Tg = −25 ° C., the secondary bobbin 2 is placed in an environment where the temperature changes from 130 ° C. to −40 ° C., and contracts due to a temperature drop after the operation is stopped. Then, in the range of 130 ° C. to −25 ° C., the secondary bobbin 2 has substantially no stress because the contraction of the secondary bobbin 2 is accepted by the elastic absorption of the soft epoxy resin 17. In the temperature range of −25 ° C. to −40 ° C., the soft epoxy resin 17 shifts to a glassy state, whereby the contraction (deformation) of the secondary bobbin 2 is prevented, so that the thermal stress (σ = E · ε = E · α · T) occurs. E is the Young's modulus of the secondary bobbin 2, ε is the strain, α is the linear expansion coefficient of the secondary bobbin, and T is the temperature change (temperature difference). Allowable stress σ of secondary bobbin 2₀Is larger than the generated stress σ (σ <σ₀), The secondary bobbin 2 is not damaged.
[0059]
In this case, even if the soft epoxy 17 between the secondary bobbin 2 and the center core 1 becomes lower than the glass transition point and becomes hard in the range of -40 ° C. to Tg (Tg is, for example, normal temperature or lower), the thermal shock relaxation effect is lost. Since the temperature range is narrow, thermal shock is weakened, and the soundness between the secondary bobbin and the center core can be maintained. Tg is not limited to −25 ° C.
[0060]
In this example, the secondary bobbin 2 has a linear expansion coefficient α in a range of room temperature (20 ° C.) to 150 ° C., including a flow direction at the time of molding and a right angle direction of 10 to 45 × 10 °.⁶The soft epoxy resin 17 has a glass transition point of −25 ° C. or higher and a Young's modulus of 1 × 10⁸(Pa) It has the following elasticity. Under these conditions, a temperature change of 130 ° C. to −40 ° C. was repeatedly given to observe the secondary bobbin 2, and it was found that the secondary bobbin 2 was not damaged. It was confirmed that soundness was maintained. That is, under the above conditions, the allowable stress σ of the secondary bobbin 2₀Is larger than σ. Since the relative permittivity of PPS is 3.8 at room temperature, the modified PPO is 3.0, and the epoxy resin (including flexible epoxy resin) is 3.5, when PPS is used for the secondary bobbin 2, The relative dielectric constant of the secondary bobbin and the insulating resin interposed between the secondary bobbin and the center core can be made closer (substantially equal) to that of the modified PPO. As the difference in the relative permittivity between the secondary bobbin and the insulating resin interposed between the secondary bobbin and the center core is reduced, the electric field concentration between the secondary bobbin and the center core of the inner secondary coil structure can be reduced. it can.
[0061]
Next, the epoxy resin 8 is filled as follows.
[0062]
As shown in FIG. 1, the circuit case 9 with a connector coupled to the coil case 6 has a bottom portion 9 </ b> E communicating with the upper portion of the coil case 6, and from the inside of the circuit case 9 with the connector, the secondary coil 3 of the coil case 6. The epoxy resin 8 is vacuum-injected between the primary bobbin 4 and between the primary coil 5 and the coil case 6 and is heated and cured at atmospheric pressure.
[0063]
Epoxy resin 8 ensures insulation between the secondary coil 3 and the primary bobbin 4 and between the primary coil 5 and the coil case 6. The epoxy resin 8 is harder than the soft epoxy resin 17.
[0064]
The epoxy resin 8 is mixed with quartz powder and molten glass powder in a total of 50% to 70% in order to improve heat resistance stress (repeated stress of −40 ° C. and 130 ° C.) and high voltage resistance under high temperature. The subsequent glass transition point is 120 ° C. to 140 ° C., and the linear expansion coefficient in the range from room temperature (20 ° C.) to the glass transition point is 18 to 30 × 10 °.⁶And the linear expansion coefficient difference between the coil portion and the metal is minimized as in the case of the primary bobbin 4 and the secondary bobbin 2. Since cracks occur due to thermal strain when the epoxy resin 8 is 0.3 mm or less, 0.4 mm or more is required from the viewpoint of mechanical strength. Further, in order to maintain a withstand voltage of about 30 kV, the thickness is required to be about 0.9 mm. In this example, the layer thickness of the insulating epoxy resin 8 between the secondary coil 3 and the primary bobbin 4 is set to 0.9 to 0.9 mm. It is about 1.05 (mm).
[0065]
In addition, since the epoxy resin 8 filled between the primary coil 5 and the coil case 6 does not require a withstand voltage and cracks are allowed, the layer thickness may be 0.4 mm or less. It is about 0.15 to 0.25 mm.
[0066]
As described above, the recess 17 ′ of the soft epoxy resin 17 is filled with the epoxy resin 8.
[0067]
The insulating layer between the secondary coil 3 and the center core 1 is composed of the soft epoxy resin 17 and the secondary bobbin 2, and the thickness of these insulating resins is set under the following considerations.
[0068]
Since the soft epoxy resin 17 has a lower insulating property than the bobbin material, it is desired to reduce the thickness as much as possible and to increase the thickness of the secondary bobbin 2 having a high insulating property. Therefore, a minimum of 0.1 mm is required in order to ensure dimensional variations in mass production of bobbin materials and cores and smoothness of voidless vacuum casting. For example, it is set to 0.1 to 0.15 ± 0.05 (mm).
[0069]
On the other hand, when the bobbin material is PPS, the thickness of the secondary bobbin 2 is required to be 0.5 mm or more from the viewpoint of moldability and mechanical strength (strength that does not cause cracks due to thermal stress (thermal strain)). From the standpoint of insulation performance, the required thickness of the secondary bobbin 2 is as follows.
[0070]
As shown in FIG. 8, for example, when the generated voltage of the secondary coil 3 is 30 kV (high voltage), the center potential is considered to be 30/2 = 15 kV because the center core 1 is not grounded. When the low voltage side of the secondary coil 3 is viewed from the center core 1, the potential difference is −15 kV, and when the high voltage side of the secondary coil 3 is viewed from the center core 1, the potential difference is +15 kV. Therefore, it is considered that the withstand voltage of the secondary bobbin may be about 15 kV. On the other hand, when PPS is used as the bobbin material, the insulation performance is about 20 kV / mm, so that it is 0.75 mm or more to withstand the voltage of 15 kV.
[0071]
The withstand voltage of the secondary bobbin 2 varies depending on the output of the secondary coil 3, but in this example, the withstand voltage (the output voltage of the secondary coil) is considered considering the output voltage of the secondary coil 3 in the range of 25 to 40 kV. / 2) under a condition satisfying the requirement of 0.5 to 1.2 mm.
[0072]
The Young's modulus of the high filler PPS is twice that of the modified PPO. Therefore, in the case where the material of the secondary bobbin 2 is modified PPO instead of the above-mentioned PPS, in order to satisfy mechanical strength, the wall thickness needs to be at least twice as large as PPS, and at least 1.0 mm is required. is there. The insulation performance of the modified PPO is 16 to 20 kV / mm.
[0073]
In other words, from the viewpoint of mechanical strength, when the high filler PPS is used for the secondary bobbin 2, the thickness can be reduced to half of that of the modified PPO.
[0074]
Further, the thickness of the secondary bobbin 2 is not uniform, and the secondary bobbin 2 has a bottomed shape, and the secondary coil low pressure side is opened to serve as the injection side of the insulating resin. As shown in FIG. 6, the inner bobbin is provided with a gradient having a difference in the inner diameter where the low pressure side of the secondary coil is large toward the high pressure side of the secondary coil and the secondary bobbin thickness on the low pressure side of the secondary coil is large. The secondary bobbin has a bobbin structure in which the thickness of the secondary bobbin is increased toward the high pressure side of the secondary coil.
[0075]
FIG. 6 is exaggerated in the drawing in order to make the gradient of the wall thickness of the secondary bobbin 2 easier to see, but the size is, for example, when the outer diameter of the secondary bobbin is Φ10 to 12 mm, the soft epoxy resin is injected. The thickness of the secondary bobbin on the side (low pressure side of the secondary coil) is 0.75 ± 0.1 (mm), and the thickness on the side opposite to the resin injection side (high pressure side of the secondary coil) is 0.9 ± 0.1 (mm). ).
[0076]
Setting the thickness specification of the secondary bobbin 2 as described above has the following advantages.
[0077]
That is, as described above, the gap between the soft epoxy resin 17 filled between the secondary bobbin 2 and the center core 1 is desired to be as thin as possible from the demand for securing the thickness of the secondary bobbin 2, and the smallest gap is 0. .About.0.15 ± 0.05 (mm), which is the gap l between the secondary bobbin and the center core on the side opposite to the soft epoxy resin injection side.₁Then, the gap l between the secondary bobbin and the center core on the soft epoxy resin injection side is₂Is 0.2 to 0.4 (mm) by providing the thickness gradient of the secondary bobbin, and therefore, the opening of the injection is widened to facilitate the resin injection, and further, the opening of the resin injection is widened. However, since the gap between the center core 1 and the secondary bobbin 2 gradually narrows, the thickness of the soft epoxy resin 17 is kept as thin as possible.
[0078]
As shown in FIG. 9, the coil portion of the ignition coil device (the portion including the coil case 6 and the coil and core housed therein) has a secondary coil high pressure side connected to the ignition plug 22 of the cylinder head 100. Because it is directly connected, it is easily affected by the thermal effects of engine combustion. (The outer surface temperature of the coil case 6 is 140 ° C. at the part directly connected to the spark plug 22, 130 ° C. near the secondary coil high pressure side. The vicinity of the low pressure side of the secondary coil is outside the cylinder head, and the distance from the high pressure side of the secondary coil is about 80 to 105 mm, so that 110 ° C., and the ignition circuit case thereover is about 100 ° C.).
[0079]
Therefore, the secondary coil high-pressure side of the secondary bobbin 2 is in a higher temperature state than the secondary coil low-pressure side, and the insulation performance is reduced. [For example, in the case of PPS used as the material of the secondary bobbin 2, the withstand voltage (The breakdown voltage is 20 kv / mm at room temperature (20 ° C.), 18 kv / mm at 100 ° C., and 17 kv / mm at 120 ° C.). Also, it is sufficiently expected that the thermal stress will increase. The thickness of the secondary bobbin on the low voltage side of the secondary coil is reduced, and the thickness of the secondary bobbin is increased toward the high voltage side of the secondary coil. Thus, the thermal effects of the engine combustion described above can be dealt with.
[0080]
The structure of the secondary bobbin 2 and the primary bobbin 4 and the combination of the bobbins (coil combination) will be described later.
[0081]
The coil case 6 is formed of a thermoplastic resin such as PPS, modified PPO, PBT or the like from the viewpoint of heat resistance, or a mixed resin in which modified PPO is mixed with PPS, for example, about 20% (mixing mode is as follows). In the sea-island structure, the sea is PPS and the island is modified PPO).
[0082]
Among them, the coil case 6 in which the modified PPO is mixed with the PPS as a compounding agent has good adhesion to the epoxy resin 8 and excellent withstand voltage, and excellent in water resistance and heat resistance (PPS is heat-resistant, Although it is excellent in voltage resistance and water resistance, it is inferior in adhesion to an epoxy resin by itself, and the adhesion is improved by blending a modified PPO with good adhesion to an epoxy resin to compensate for it.) The wall thickness of the coil case 6 is about 0.5 to 0.8 mm. In addition, inorganic powders such as glass fiber and talc are appropriately blended as fillers in the thermoplastic resin to be the coil case 6 as well as the bobbin material in order to minimize the difference in linear expansion coefficient from the metal of the coil portion as in the bobbin material. .
[0083]
It should be noted that a mixture of the above-mentioned PPS and the modified PPO as a compounding agent has the above-mentioned advantages, and thus may be used for the above-mentioned primary bobbin and secondary bobbin. It is possible to satisfy the impact property, the insulation performance, and the thickness reduction, and further, it is possible to enhance the adhesion to the epoxy resin 8 and the flexible epoxy resin 17.
[0084]
A circuit case 9 (sometimes called an ignition control unit case or an igniter case) 9 with a connector 9B disposed above the coil case 6 is formed separately from the coil case 6, and is similar to the PBT or the coil case 6. It is molded of the material.
[0085]
The circuit case 9 accommodates a unit 40 of a drive circuit (ignition circuit) for ignition control and is integrally formed with a connector (connector housing) 9B. The circuit case 9 and its connector terminals will be described later.
[0086]
The side core 7 mounted on the outer surface of the coil case 6 constitutes a magnetic path in cooperation with the center core 1, and is formed of a thin silicon steel sheet or a directional silicon steel sheet having a thickness of about 0.3 to 0.5 mm. Rolled and molded. The side core 7 is provided with a cut in the axial direction at least at one position on the circumference of the side core 7 in order to prevent a short turn of magnetic flux. In this embodiment, the side core 7 is formed by stacking a plurality of silicon steel sheets (here, two sheets) to reduce the eddy current loss and improve the output. The number may be set appropriately according to the material (aluminum, iron, etc.) of the plug hole or the like.
[0087]
The coil portion of the pencil coil of the present example has, for example, an outer diameter of the coil case 6 of about 22 to 24 mm and an area of the center core 1 of 50 to 80 mm.²The length (bobbin length) of the coil portion is about 86 to 100 mm, the outer diameter of the secondary bobbin is about 10 to 12 mm, and the outer diameter of the primary bobbin is about 16 to 18 mm. Is determined. In this example, the primary bobbin 4 and the coil case 6 are also provided with a thickness difference of about 0.15 mm so that the resin injection side is thinner and the opposite side is thicker.
[0088]
Above the secondary bobbin 2, a bobbin head 2A is formed integrally with the secondary bobbin 2. The bobbin head 2A is set so as to be located above the upper end of the primary bobbin 4.
[0089]
FIG. 10 is an enlarged perspective view of the vicinity of the bobbin head 2A after the step of winding the secondary coil 3 around the secondary bobbin 2, and FIG. 11 shows a case where the secondary bobbin 2 of FIG. Is an enlarged perspective view of the vicinity of the bobbin head 2A. In FIG. 1, the bobbin head 2 </ b> A is partially sectioned, and a portion that is not sectioned is a part of the outer surface of the bobbin head.
[0090]
The bobbin head 2A of this embodiment has a rectangular box shape, and the secondary bobbin 2 is inserted into the outer surface of the bobbin head 2A in the rotary shaft 62 (see FIG. 18) of the winding machine in the process of manufacturing the ignition coil. In this case, an engaging portion 2D is provided which engages with a detent 64 for both bobbin positioning provided on the rotary shaft side.
[0091]
The engaging portion 2D of the present example has a ridge extending in the bobbin axis direction. The detent 64 on the rotating shaft 62 side connects two pins 64 parallel to the axial direction of the shaft 62 to one end surface of the coupling 63. The convex strip engaging portion 2D is fitted between the pins 64.
[0092]
The inside of the bobbin head 2A is filled with a magnet 16 and a soft epoxy resin 17 as shown in FIG. 1 through an upper opening. In addition, despite being on the side of the secondary bobbin 2, a coil terminal 18 and a primary coil terminal 19 are provided on the outer surface of the bobbin head 2A for both primary and secondary coils.
[0093]
Here, the primary / secondary coil dual-purpose terminals 18 correspond to the dual-purpose terminals (1) and (3) in FIG. 9B. That is, a coil terminal (corresponding to the terminal (3) in the circuit of FIG. 9A) for taking out one end 3a of the secondary coil 3 and connecting it to a power supply, and taking out one end 5a of the primary coil 5 for power supply It functions as a coil terminal for connection (corresponding to terminal (1) in the circuit of FIG. 9A).
[0094]
On the other hand, the primary coil terminal 19 corresponds to the terminal (2) in the circuit of FIG. 9 (a) and FIG. 9 (b), and takes out the other end 5b of the primary coil 5 and outputs the power transistor (ignition coil drive) of the ignition circuit unit. (Element) 39.
[0095]
As shown in FIGS. 10 and 11, the primary / secondary coil combined terminal 18 is formed of a band-shaped metal plate, and is attached to a pocket 20 provided on one outer surface of the secondary bobbin head 2A via its mounting leg 18c. Press-fit fixed. The one end 18 'is formed into an L-shape, and the rising portion 18' is joined to the one end 31b of the power input connector terminal 31 by welding or the like as shown in FIGS. FIG. 12 shows a bobbin assembly (primary bobbin) in which the coil case 6 and the ignition circuit case 9 are removed from the ignition coil device, the primary bobbin 4 around which the primary coil 5 is wound, and the secondary bobbin 2 around which the secondary coil 3 is wound. FIG. 13 is an enlarged perspective view showing a coupling relationship between a secondary coil assembly) and an ignition circuit unit (sometimes referred to as an igniter) 40 installed on the secondary bobbin head 2A, and is an ignition circuit unit 40 in FIG. The lead terminals 32, 34, and 36 are actually housed in a circuit case 9 with a connector 9B as shown in FIG. 3, and the connector terminals 31, 33, and 35 are placed in the circuit case (resin case) 9. Part of it is buried.
[0096]
The primary / secondary coil dual-purpose terminal 18 is made of a metal fitting alone. As shown in FIGS. 10 and 11, one end 3a of the secondary coil 3 is pulled out and wound (wrapped), and one end 5a of the primary coil 5 is connected. The pull-out portion 18b is integrally formed, and the coil ends 3a, 5a are soldered after the coil ends 3a, 5a are tied off at the lashing portions 18a, 18b, respectively. A notch 2C for guiding one end 3a of the secondary coil to the terminal fitting 18 is formed in the upper end flange (flange portion) 2B 'of the secondary bobbin 2, and the primary coil is similarly formed in the upper end flange 4A of the primary bobbin 4. A notch 4B for guiding one end 5a to the terminal fitting 18 is formed.
[0097]
The primary coil terminal 19 is also formed of a band-shaped metal plate, and is press-fitted and fixed to a pocket (not shown) provided on the outer surface of the secondary bobbin 2 on the side opposite to the position where the pocket 20 is located. An arm 19 ″ is formed in an L-shape and formed to extend horizontally toward the primary / secondary coil dual-purpose terminal 18 side, and the distal end 19 ′ is connected to the distal end 18 ′ on the terminal 18 side. This primary coil terminal 19 is connected by welding to a lead terminal (lead terminal) 32 on the ignition circuit unit 40 side as shown in Fig. 12. As shown in FIG. 1 and FIG. 3, the collector side of the power transistor 39 of the ignition circuit unit 40 is electrically connected via the wire bonding 42.
[0098]
As shown in FIG. 15, the connector terminals (connector pins) include connector terminals 33 and 35 in addition to the connector terminal 31 described above.
[0099]
Here, the relationship between the connector terminals 31, 33, 35 and the drive circuit for ignition control will be described.
[0100]
FIG. 4 is an electric wiring diagram of the ignition circuit 41 mounted on the circuit case 9 of the ignition coil device 21, the primary coil 5, and the secondary coil 3.
[0101]
One end 5a of the primary coil 5 and one end 3a of the secondary coil 3 are connected to the + side of the DC power supply via the primary / secondary coil shared terminal 18 and the connector terminal 31 provided on the secondary bobbin 2. The primary / secondary coil dual-purpose terminal 18 corresponds to the primary / secondary coil dual-purpose terminal (1) (3) described in the ignition coil principle diagram of FIG.
[0102]
The other end 5b of the primary coil 5 is connected to the collector side of the power transistor 39 connected in Darlington via the primary coil terminal 19 provided on the secondary bobbin and the lead terminal 32 provided on the ignition circuit unit 40. The primary coil terminal 19 corresponds to the primary coil terminal (2) described above.
[0103]
The other end 3b of the secondary coil 3 is connected to the ignition plug 22 via the high voltage diode 10. The high-voltage diode 10 serves to prevent premature ignition when a high voltage generated in the secondary coil 3 is supplied to the ignition plug 22 via the leaf spring 11, high-voltage terminal 12, and spring 13 shown in FIG.
[0104]
An ignition control signal generated by an engine control unit (not shown) is input to the base of a power transistor 39 via a connector terminal 33 and a lead terminal 34 provided on the ignition circuit unit 40. Based on the ignition control signal, the power transistor 39 is turned on and off to control the energization of the primary coil 5, and a high voltage for ignition is induced in the secondary coil 3 when the primary coil 5 is cut off.
[0105]
The emitter side of the second stage transistor of the power transistor 39 is connected to the ground via a lead terminal 36 and a connector terminal 35 provided on the ignition circuit unit 40.
[0106]
From the above, as shown in FIGS. 3 and 12, one end 18 'of the primary / secondary coil dual-purpose terminal 18 and one end 31b of the connector terminal 31 are connected by welding, and one end 19' of the primary coil terminal 19 is connected to the other end. One end of the lead terminal 32 on the ignition circuit unit side is connected by welding, one end of the connector terminal 33 and one end of the lead terminal 34 on the ignition circuit unit side are connected by welding, and one end of the connector terminal 35 and one end of the lead terminal 36 are welded. Connected by
[0107]
In FIG. 4, reference numeral 71 denotes a noise prevention capacitor for preventing noise generated by controlling the energization of the ignition coil, which is disposed between the power supply line and the ground, and in this example, is disposed outside the case accommodating the ignition circuit unit. I have. For example, the noise prevention capacitor 71 is disposed at a ground point of a wiring (engine harness) in an engine room.
[0108]
The resistor 72 provided between the ignition signal input terminal 34 and the base of the power transistor 39 and the capacitor 73 provided between the resistor 72 and the ground form a surge protection circuit. The transistor 74, the resistor 76 and the zener diode 75 form an overcurrent limiting circuit of the ignition control system. Reference numeral 77 denotes a primary voltage limiting diode, and reference numeral 78 denotes a diode constituting a protection circuit when a reverse current is applied.
[0109]
As shown in FIGS. 1, 3, and 12, the lead terminals 32, 34, and 36 on the ignition circuit unit 40 side are synthetic resin terminals bonded to an aluminum metal base 37 that is press-formed in a box shape. It is fixed on a table 38. Also, the terminals 18, 31, 19, 32, 33, 34, and 35, 36 described above are arranged in parallel with their joints facing in the same direction, so that welding can be easily performed. is there.
[0110]
The ignition circuit unit 40 includes a hybrid IC circuit 41 including the above-described resistor 72, capacitor 73, transistor 74, zener diode 75, resistor 76, zener diode 77, and diode 78, and a power transistor 39 in a metal base 37. The metal base 37 is filled with silicon gel.
[0111]
The circuit case (igniter case) 9 that houses the ignition circuit unit 40 is molded integrally with the connector housing 9B that houses the connector terminals 31, 33, and 35 described above.
[0112]
As shown in FIGS. 1 and 3, the circuit case 9 has a case accommodating the ignition circuit unit 40 surrounded by a case side wall 9A, and the ignition circuit unit 40 has a space surrounded by the side wall 9A as shown in FIG. Is placed on the floor surface (inside) 9E of the first member by being guided by the positioning projection 9D. The center of the floor surface 9E is open so as to face the opening surface on the coil course 6 side.
[0113]
The circuit case 9 is formed separately from the coil case 6 and is joined to the upper end of the coil case 6 by fitting and bonding. In this connection state, as shown in FIG. 3, the projection 6A provided on the upper outer periphery of the coil case 6 is engaged with the concave groove 9F on the circuit case 9 side in a detented state.
[0114]
The metal base 37 of the ignition circuit unit 40 housed in the circuit case 9 in the coupled state is disposed immediately above the head 2A of the secondary bobbin 2, and one end 31 'of the connector terminal 31 of the circuit case 9 and the lead terminal 32 Is set so that one end of each of the primary and secondary coil terminals 18 and the primary coil terminal 19 provided on the secondary bobbin head 2A side overlaps in the circuit case 9, and welding of these overlapping terminals is performed. Is designed to be easily performed. When the ignition circuit unit 40 is set, the lead terminals 34 and 36 on the ignition circuit unit 40 side are naturally aligned with the corresponding connector terminals 33 and 35, respectively.
[0115]
Further, the circuit case 9 has a flange 9C formed around the side wall 9A, and a screw hole 25 for attaching the ignition coil device 21 to the engine cover is provided in a part of the flange 9C. The inside of the circuit case 9 is covered with an insulating epoxy resin 43.
[0116]
Next, the structure on the bottom side of the secondary bobbin 2 and the primary bobbin 4 will be described with reference to FIGS.
[0117]
FIG. 13 is a perspective view of the vicinity of the bottom when the secondary bobbin 2 and the secondary coil 3 are inserted into the primary bobbin 4. FIG. 14 shows a bottom view of the primary bobbin 4 and the secondary bobbin 2 and a bottom view of a state in which they are assembled.
[0118]
As shown in FIGS. 13 and 14, the secondary bobbin 2 is formed in a closed-end cylindrical shape with a closed bottom, and a projection 2E for attaching the high-voltage diode 10 is provided on the outer surface of the bottom. One end 3b of the secondary coil 3 is connected to a high voltage terminal 12 via a high voltage diode 10 and a leaf spring 11, as shown in FIG.
[0119]
The bottom of the primary bobbin 4 is open, and when the secondary bobbin 2 is inserted into the primary bobbin 4, the high-voltage diode 10 projects from the bottom opening 4 'of the primary bobbin 4. A pair of secondary bobbin receivers 4D opposed to each other at the bottom of the primary bobbin 4 so as to sandwich the opening 4 'are arranged so as to protrude below a bottom flange (bottom end surface) 4C of the primary bobbin 4. Is established.
[0120]
The secondary bobbin receiver 4D receives the secondary bobbin 2 via its flange portion 2B (the lowermost flange). The opposing sides of the bobbin receivers 4D are straight, and the remaining contours are arc-shaped. A concave portion (groove portion 51) is provided in the radial direction from the center of the side, and the secondary bobbin 2 and the primary bobbin 4 are engaged with the convex portion 52 provided on the bottom outer periphery of the secondary bobbin 2. The relative detent is aimed at.
[0121]
The bottom flange 4C of the primary bobbin 4 is provided with a pair of downwardly directed projections 53. The projections 53 are provided on a primary bobbin receiver 6A provided on a part of the inner periphery of the coil case 6 as shown in FIG. By engaging with the positioning groove 6B, the relative rotation between the coil case 6 and the primary bobbin 4 is prevented.
[0122]
As shown in FIG. 14B, the bottom 2 of the secondary bobbin 2 has a cut surface 2G that is substantially circular but slightly flat on the left and right, and this cut surface 2G is shown in FIG. Thus, the secondary bobbin receiver 4D is located at the bottom opening 4 'of the primary bobbin 4 in conformity with the opposite side (straight line). Further, the convex portion 52 is provided at the position of the cut surface 2G.
[0123]
The concave portion 51 formed in the secondary bobbin receiver 4D is provided with a taper 51 'at the upper end as shown in FIG. Even if the position 52 is slightly displaced from the concave portion 51, it is guided by the taper 51 'to make it easy to enter.
[0124]
The secondary bobbin receiver 4D provided on the bottom of the primary bobbin 4 is disposed opposite to the bottom opening 4 'and projects downward from the bottom of the primary bobbin 4 so that the secondary bobbin receiver 4D is provided at the bottom of the primary bobbin 4. A side space 4 "without 2D can be secured. Through this side space 4", as shown by an arrow P in FIG. 14 (d), when the insulating resin 8 'is injected, the primary bobbin 4 and the secondary bobbin 2 ( The resin circulation between the gap between the inner and outer circumferences of the secondary coil 3) and the inner and outer circumferences of the coil case 6 and the primary bobbin 4 (primary coil 5) is improved so that the resin in the injected insulating resin at the bottom of the primary bobbin 4 is improved. Bubbles are made to escape.
[0125]
At the bottom of the secondary bobbin 2, a magnet 15 and a foam rubber 45 are arranged in a laminated manner, and the center core 1 is inserted therein. The magnet 15 and the magnet 16 provided on the secondary bobbin head 2A generate magnetic fluxes in opposite directions in the magnetic paths (the center core 1 and the side cores 7), so that the ignition coil is moved below the saturation point of the magnetization curve of the core. Can work.
[0126]
The foamed rubber 45 absorbs a difference in thermal expansion between the center core 1 and the secondary bobbin 2 due to a temperature change during the injection and use of the insulating resin 8 of the ignition coil device 21 (thermal stress relaxation).
[0127]
At the lower end of the coil case 6, a cylindrical wall 6 ′ for inserting an ignition plug 22 (see FIG. 5) is formed so as to surround the spring 13. The cylinder wall 6 'is formed integrally with the coil case 6, and a boot, for example, a rubber boot 14 made of a flexible insulating material for attaching the ignition plug 22 while insulating the cylinder wall 6' is attached.
[0128]
FIG. 5 shows a state in which the ignition coil device 21 having the above configuration is mounted in the plug hole 23 of the engine.
[0129]
The coil portion of the ignition coil device 21 penetrates through the engine head cover (cover covering the cylinder head) 24, is inserted into the plug hole 23B through the guide tube 23A, and the rubber boot 14 comes into close contact with the periphery of the ignition plug 22. A part of the ignition plug 22 is introduced into the one end cylindrical wall 6 'of the coil case 6 and presses the spring 13 so that the ignition coil device 21 is directly connected to the ignition plug 22 in the plug hole 23B. The ignition coil device 21 is configured such that a screw hole 25 (see FIG. 1) provided in the circuit case 9 and a screw hole 26 provided in the engine cover 24 are tightened by screws 27, and a seal rubber 28 provided on the upper part of the coil case 6 is fixed to a head cover of the engine. It is fixed by fitting it into an annular projection 29 provided on the periphery of the 24 insertion hole of the ignition coil device.
[0130]
A vertical groove 92 is provided on the inner surface of the seal rubber 28 as shown in FIG. When the seal rubber 28 is mounted together with the ignition coil device 21, the vertical groove 92 allows the air in the flange of the seal rubber 28 (the portion fitted into the convex portion 29 on the engine cover side) to escape to facilitate the mounting work of the seal rubber 28. And maintaining the atmospheric pressure state by communicating the inside of the engine cover 24 with the atmosphere. The latter function is that if the groove 92 is not provided, the inside of the engine head cover 24 which is in a high temperature state due to engine heat will be in a negative pressure state when the engine cover is rapidly cooled due to the water applied to the engine cover. Even if it is present, water accumulated around the seal rubber 28 is drawn in by the negative pressure, so that such negative pressure is prevented. The air intake of the groove 92 is formed by the accumulated water on the engine cover. It is set at a position somewhat higher than the engine cover so that water (water that has entered the vehicle by splashing water on the road and attached to the engine cover) does not flow.
[0131]
In this embodiment, even when the head cover 24 of the engine head (cylinder head) 100 is made of plastic (for example, 6 nylon, 66 nylon) and an ignition coil device of an independent ignition type is attached thereto, the coil portion has a plug hole. The center of gravity W of the ignition coil is shifted to a position lower than the head cover 24, here, into the ignition coil guide tube 23A by being inserted into the guide tube 23B and 23A (the center of gravity W makes the length of the coil portion of the pencil coil 85 to 100 mm). Is located 50 to 70 mm below the upper end of the coil portion). In addition, the circuit case 9 with a connector, which is relatively light in the pencil coil, is fixed to the outer surface of the plastic head cover 24 (for example, by screwing 27), and the axial direction is determined at the plug coupling position between the fixing portion and the plug hole. Since the two-point support can be achieved, the vibration of the entire ignition coil device can be reduced, and the vibration of the ignition coil device applied to the plastic head cover 24 can be suppressed, and the lightweight (thin wall) and simplification of the plastic head cover can be achieved while the independent ignition type coil device is achieved. Can be realized.
[0132]
Next, a procedure for manufacturing the ignition coil device 21 having the above configuration will be described with reference to FIGS.
[0133]
As shown in FIG. 16, the secondary coil 3 is wound around the secondary bobbin 2, and one end 3 a of the secondary coil is connected to the primary / secondary coil combined terminal 18. This connection is made by winding the coil end 3a around the terminal 18 and soldering it. The other end 3b of the secondary coil 3 is also connected to a secondary coil terminal (here, a high voltage diode 10) on the high voltage side. Next, a continuity test is performed.
[0134]
The secondary bobbin 2 on which the secondary coil 3 is wound is interpolated and fixed to the primary bobbin 4, and in this state (primary and secondary bobbin superimposed state), the primary coil 5 is wound around the primary bobbin 4, and the primary coil is wound. Is connected to the primary / secondary coil combined terminal 18, and the other end 5 b of the primary coil is connected to the primary coil terminal 19. These connections are made by coil winding and soldering. In this case, even if the primary / secondary coil combined terminal 18 and the primary coil terminal 19 are provided on the secondary bobbin 2 side, the terminals 18 and 19 are located outside one end of the primary bobbin 4 together with the secondary bobbin head 2A. Therefore, both ends 5a and 5b of the primary coil 5 can be easily guided to the terminals 18 and 19, and the above-mentioned lashing and soldering work can be performed. Next, a continuity test of the primary coil is performed.
[0135]
Next, after the leaf spring 11 (see FIG. 17) is connected to the lead terminal of the high voltage diode 10 so as to be connected to the high voltage diode 10, the foam rubber 45, the magnet 15, the center core 1, and the magnet 16 are placed in the secondary bobbin 2. Then, a soft epoxy resin 17 is injected into the secondary bobbin 2 and cured.
[0136]
Here, a winding machine used in the winding step of the secondary coil 3 and the winding step of the primary coil 5 is not shown, but basically, a bobbin is set on a rotating shaft and the bobbin is rotated. Although the enamel wire is wound, various applications are conceivable as application examples.
[0137]
One is equipped with an enamel wire reel for the primary coil and an enamel wire reel for the secondary coil in one winding machine, and draws out each enamel wire from these reels and winds them around the rotating shaft. It is conceivable to use a single winding machine to wind the primary coil and the secondary coil with a hand mechanism for performing the reciprocating operation, the turning operation, etc. necessary for the lashing. In this case, in this embodiment, According to the secondary bobbin structure used, the rotary shaft of the winding machine can be shared.
[0138]
FIG. 18 shows a rotation mechanism of the winding machine. The rotating mechanism is roughly divided into a rotating shaft 62 and a motor 61. The rotating shaft 62 is detachable from an output shaft 62 '(see FIG. 19) of the motor 61 via a joint (coupling) 63 forming a part of the shaft 62. And a joint structure in which the rotating shaft 62 rotates integrally with the output shaft 62 '. The rotary shaft 62 is formed in a split pin shape by cutting a slit 65 from the tip to a midway position of the shaft, and at least a portion 62A of the split pin portion of the rotary shaft 62 is in a secondary state before the secondary bobbin 2 is inserted. A taper 62 </ b> B that extends beyond the inner diameter of the bobbin 2 and guides the secondary bobbin 2 is formed at the end. Also, two pins 64 for bobbin positioning and rotation preventing which engage with the engaging portion 2D provided on the secondary bobbin head 2A are provided on a part of the rotating shaft 63 (here, one end surface of the joint 63). The engaging portion 2D of the secondary bobbin head 2A is engaged between the pins 64.
[0139]
When the above-mentioned common winding machine is used, first, as shown in FIGS. 18A and 18B, the secondary bobbin 2 is pushed into the rotating shaft 62 of the winding machine using the shaft taper 62B. The split pin portion 62A of the shaft 62 is elastically deformed in the direction in which the diameter becomes smaller, and the secondary bobbin 2 is inserted and set in the rotary shaft 62. At this time, the split pin portion 62A is caused to resiliently return to the inner surface of the bobbin 2. , And both ends of the secondary bobbin 2 are firmly fixed on the rotary shaft 62 by engaging the engaging portion 2D provided on the secondary bobbin head 2A between the detent pins 64 of the rotary shaft. .
[0140]
Therefore, even when the secondary bobbin 2 is cantilevered by the rotary shaft 62 at the time of the secondary winding and the secondary bobbin 2 is rotated at high speed integrally with the rotary shaft 62, the secondary bobbin 2 does not slip or rotate. In addition, it enables the winding of the secondary coil 3 which requires high-precision precision winding.
[0141]
After performing winding (including soldering) of the winding of the secondary coil 3 and the end of the secondary coil to the coil terminal 18, the secondary bobbin 2 is attached to the rotating shaft 62 as shown in FIG. The primary bobbin 4 is fitted to the outside of the secondary bobbin via detents 52 and 51 (shown in FIGS. 13 and 14) between the bobbins, and one end of the primary bobbin 4 (the secondary bobbin (The side where the high voltage diode 10 is located) is rotatably supported, and the primary bobbin 4 is rotated together with the secondary bobbin 2 to wind the primary coil 5 around the primary bobbin 4.
[0142]
In addition to such a winding method, the winding machine for the secondary coil and the winding machine for the primary coil are separate, and only the rotating shaft 62 for winding is detachable as shown in FIG. It is also possible to share the primary winding machine and the secondary winding machine.
[0143]
In this case, first, the rotating shaft 62 is attached to the winding machine (here, the motor of the secondary winding machine) in the same manner as in FIG. The secondary bobbin 2 is inserted and set to the secondary bobbin via the head 2A, and the secondary coil 3 is wound around the secondary bobbin 2 by rotating the secondary bobbin 2 together with the rotary shaft 62.
[0144]
Thereafter, the rotary shaft 62 is detached from the secondary winding machine while the secondary bobbin 2 is mounted (see FIG. 19), and the rotary shaft 62 is mounted on the primary winding machine, and the primary bobbin is placed outside the secondary bobbin 2. The primary bobbin 4 is rotated together with the secondary bobbin 2 by winding the primary coil 5 around the primary bobbin 4 by fitting the primary bobbin 4 with the detents 51 and 52 between the bobbins as in FIG.
[0145]
The coil assembly manufactured through the series of steps shown in FIG. 16 is inserted into the assembly of the coil case 6 and the circuit case 9 together with the high-voltage terminal 12, the leaf spring 11, and the ignition circuit unit 40 as shown in FIG. . Here, as described above, the primary / secondary coil dual-purpose terminal 18 and the connector terminal 31, the primary coil terminal 19 and the lead terminal 32 on the ignition circuit unit side, the connector terminal 33 and the lead terminal 34 on the ignition circuit unit side, The connector terminal 35 and the lead terminal 36 are respectively connected by projection welding.
[0146]
Prior to inserting the coil assembly into the coil case 6, the circuit case 9 and the coil case 6 are fitted and bonded. After the coil assembly is inserted, the side core 7 is press-fitted into the coil case 6 and the rubber boot 14 is inserted. Press-fitting is performed, and the epoxy resin 8 is injected and cured.
[0147]
The main functions and effects of the present embodiment are as follows.
[0148]
(1) Even in the case of an independent ignition coil device mounted in a plug hole and exposed to a severe temperature environment, the primary bobbin 4 and the secondary bobbin 2 are made thinner, and the coil portion is made thinner (smaller). ), While improving the thermal shock resistance between the secondary bobbin 2 and the center core 1, between the secondary bobbin 2 and the secondary coil 3, between the secondary coil 3 and the primary bobbin 4, etc., thereby improving crack prevention and insulation performance. Can be achieved. In particular, when the primary bobbin and the secondary bobbin are made of PPS mixed with 50% or more of inorganic powder, the tensile strength is about 1.5 times and the linear expansion coefficient is 1 time as compared with the conventional modified PPO. Since it is about 2, there is an effect of being improved about three times against cracking, and an ignition coil for an internal combustion engine excellent in thermal shock resistance can be provided.
[0149]
(2) Further, by making the spool area of the divided winding of the secondary bobbin having the inner secondary coil structure into 12 to 14 sections (stages), the number of flange portions (the number of spool areas) of the secondary bobbin can be reduced by each spool area. In consideration of the lightening of the pressure resistance load, the restriction on the length of the secondary bobbin in the axial direction, and the trouble of winding the split coil, all of these conditions can be set within a range where they can be compromised.
[0150]
(3) Soft epoxy resin 17 is smoothly filled in the narrow gap between the center core 1 and the secondary bobbin 2 to improve the quality of the product, and the center core against repeated thermal stress in a severe temperature environment of the engine. 1. Increase the thermal shock between the secondary bobbins 2.
[0151]
(4) Since the secondary coil high pressure side of the coil portion of the ignition coil device is directly connected to the ignition plug 22 of the cylinder head, the secondary coil high pressure side is most thermally affected by engine combustion. Therefore, without any consideration, the secondary coil high-pressure side of the secondary bobbin 2 is in a higher temperature state than the secondary coil low-pressure side, resulting in reduced insulation performance and increased thermal stress. It becomes. In the present invention, the thickness of the secondary bobbin on the secondary coil low-voltage side is reduced and the thickness of the secondary bobbin is increased toward the secondary coil high-pressure side. The stress increases, and the thermal effect of the engine combustion described above can be dealt with.
[0152]
(5) By using PPS for the bobbin material such as the secondary bobbin 2 or the like, the wall thickness is reduced and the thickness of the soft epoxy resin 17 is reduced as compared with the case where these bobbin materials are molded with modified PPO. By doing so, the thickness of the other insulating material (the epoxy resin 8 between the secondary coil and the primary bobbin) can be sufficiently increased, and the insulation and thermal shock resistance of the coil mold are improved. In particular, the specifications of the outer diameter of the main body of the apparatus and the specifications of the inner and outer diameters of the primary coil 5 and the secondary coil 3 hardly change, and there is room for improvement in the above-mentioned thickness of the secondary bobbin 2. The thickness is an insulating resin layer between the center core 1 and the secondary bobbin 2, and the effect is large in that sense.
[0153]
(6) By determining the glass transition point Tg of the soft epoxy resin 17 in relation to the thermal shock resistance of the resin 17 and the allowable stress of the secondary bobbin 2, the insulating property of the coil portion of the inner secondary coil structure can be improved. Satisfies both the thermal shock resistance and the stress resistance of the important parts (the insulating layer between the center core 1 and the secondary coil 3) that require.
[0154]
(7) By setting the thicknesses of the soft epoxy resin 17, the secondary bobbin 2, the primary bobbin 4, and the epoxy resin 8 on a reasonable basis, the area occupied by the center core of the coil whose size is standardized is expanded. Thus, the output can be improved.
[0155]
(8) A pressureless molding of the soft epoxy 17 filled in the gaps between the coil components can be voided, and the insulation reliability of the pencil coil can be increased.
[0156]
(9) The components such as the center core 1 and the magnets 15 and 16 in the secondary bobbin 2 are intensively suppressed in the axial direction by the recess 17 ′ generated by the pressure molding of the soft epoxy resin 17, and the center core and the like are suppressed. Vibration resistance can be achieved. In particular, in this example, even if the insulating resin 17 is soft, since the intensive pressing force by the recess 17 ′ acts on the elastic member 45 via the center core 1, the intensive force generated by the recess 17 ′. The center core 1 is strongly fixed by a strong axial pressing force and the reaction force of the elastic member 45, and the vibration resistance to the magnetic vibration generated in the center core and the vibration caused by the engine is improved. Further, since the recess 17 'is filled with the epoxy resin 8, a gap between the circuit case 9 and the center core 1 is eliminated, and dielectric breakdown between the circuit base 37 and the center core 1 can be prevented.
[0157]
(10) Since the independent ignition type ignition coil device can be mounted on the plastic engine head cover without any trouble, the engine can be reduced in weight.
[0158]
(11) The pencil coil of this example was subjected to repeated thermal stress tests at −40 ° C./1 h (hour) and 130 ° C./1 h. Have confirmed.
[0159]
The soft epoxy 17 may be replaced by an insulating soft resin such as silicone rubber or silicone gel.
[0160]
In the present embodiment, the following effects are also obtained.
[0161]
(12) The secondary coil 3 requiring precise winding is wound in advance, and the primary bobbin 4 is secured outside the secondary bobbin 2 around which the secondary coil 3 is wound while ensuring that the bobbins do not rotate. The primary coil 5 is wound around the primary bobbin 4 by rotating the primary bobbin 4 together with the secondary bobbin 2 according to this method. However, according to this method, the primary coil 5 needs to be wound as precisely as the secondary coil 3. There is no hindrance because the winding is simple and easy. Therefore, it is possible to perform the coil winding operation in a state where the primary and secondary bobbins are assembled (overlaid).
[0162]
(13) As a result of enabling winding work in such a bobbin assembly state, the primary and secondary winding machines can be shared, or the rotating shafts of the primary and secondary winding machines can be shared, or the primary and secondary winding machines can be shared. The type of the rotating shaft of the secondary winding machine can be unified (shaft compatibility).
[0163]
(14) Further, by providing the primary / secondary coil dual-purpose terminal 18 ((1)-(3)) on the secondary bobbin 2, a crossover between the primary terminal (1) and the secondary terminal (3) as in the prior art. M (see FIG. 9 (c)) eliminates the need for connection and eliminates the step of connecting the crossover M. In addition, by assuring the primary winding in the bobbin-assembled state as described above, the primary coil 5 is directly provided on the secondary bobbin 2 without being temporarily fixed to the primary bobbin 4, and the primary / secondary coil is also used. It can be connected to terminal 18 and primary coil terminal 19. FIG. 9C shows a process of assembling a conventional outer secondary coil structure in which the primary coil is inside and the secondary coil is outside.
[0164]
(15) The head 2A of the secondary bobbin 2 inserted into the primary bobbin 4 is caught from the primary bobbin 3 so that the primary / secondary coil combined terminal 18 and the primary coil terminal 19 are provided on the secondary bobbin 2. Even in this case, a sufficient installation space can be secured.
[0165]
(16) When the circuit case 9 is connected to the upper end of the coil case 6 by fitting and bonding, one end 31 ′ of the connector terminal 31 and one end of the lead terminal 32 of the circuit case 9 are provided on the secondary bobbin head 2A side. Each terminal of the primary / secondary coil terminal 18 and the primary coil terminal 19 is set so as to overlap in the circuit case 9, and welding of these overlapping terminals is easily performed. Further, since the circuit unit 40 is accurately positioned via the positioning member 9D, the positioning with the connector terminal 33 / the lead terminal 34 on the circuit unit side and the connector terminal 34 / the lead terminal 36 on the circuit unit side is also performed accurately. . Therefore, no displacement occurs when the terminals are joined, and workability and quality improvement are improved.
[0166]
(17) A space between the inner and outer circumferences of the primary bobbin 4 and the secondary bobbin 2 (secondary coil 3) at the time of injecting the insulating resin 8 by securing a side space 4 ″ without the secondary bobbin receiver 2D at the bottom of the primary bobbin 4. To improve the resin flow between the coil case 6 and the gap between the inner and outer circumferences of the primary bobbin 4 (primary coil 5), to improve the elimination of air bubbles in the injected insulating resin at the bottom of the primary bobbin 4, and to insulate the ignition coil. Improve performance.
[0167]
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0168]
FIG. 20 is a partial cross-sectional view (DD-D cross-sectional view of FIG. 21) of the ignition device according to the second embodiment. In the figure, the same reference numerals as those used in the first embodiment indicate the same or common elements. FIG. 21 is a top view of the ignition coil device of FIG. 20, showing the inside of the circuit case 9 before filling with resin. The sectional view taken along the line FF ′ in FIG. 20 is the same as that in FIG.
[0169]
In this embodiment, main differences from the first embodiment will be described.
[0170]
The ignition noise preventing capacitor 71 (hereinafter, referred to as a noise preventing capacitor 71) in this embodiment is housed in the circuit case 9. Therefore, in addition to the above-mentioned connector terminal fittings (connector terminal 31 for power supply connection, connector terminal 33 for inputting ignition signal, terminal 35 for ignition circuit ground), a dedicated connector terminal for noise prevention capacitor 71 (terminal for capacitor ground). ) 72 is additionally accommodated in the connector housing 9B, and a noise prevention capacitor 71 is connected between the connector terminal 72 and the power supply (+ power) connector terminal 31.
[0171]
By expanding the space for accommodating the ignition circuit unit 40 in the circuit case 9 than in the first embodiment, the noise prevention capacitor 71 is installed in this accommodation space. The installation location of the noise prevention capacitor 71 is on the floor of the case 9 near the embedding position, with the middle portions of the connector terminals 31 to 35 and 72 buried in the resin of the case 9.
[0172]
Also, a part of the terminal fitting is bent vertically (including substantially vertically) at an intermediate portion of the power supply connector terminal 31 and one end of the capacitor ground terminal 72, and the bent portion (a rising portion) is formed. ) 31 c and 72 ′ are arranged on both sides of the noise prevention capacitor 71 so as to protrude from the floor of the case 9. Both lead wires 73 of the noise prevention capacitor 71 are connected to the bent portions 31c and 72 ', respectively. In this embodiment, the lead wire 73 of the capacitor 71 is soldered to the terminal bent portions 31c and 72 '.
[0173]
Here, one end (bent portion) 73 ′ of the lead wire 73 is formed in a ring shape before connecting to the terminals 31 and 72, and the ring 73 ′ is fitted into the terminal bent portions 31 c and 72 ′ from above. There is a shape that can be put. Reference numeral 9K shown in FIG. 24 denotes a projection provided on the floor surface (inner bottom) 9E of the case 9, which is formed to protrude vertically from the floor surface 9K adjacent to the terminal bent portions 31c and 72 '. The protrusions 9K are molded so that one side of the protrusions 31c and 72 'bite into the protrusions 9K, and the height of the protrusions 9K is lower than the height of the terminal bent portion 31c. When the lead wire one end 73 'is fitted down from the upper ends of the terminal bent portions 31c and 72' and lowered, the lead wire one end 73 'hits the upper end of the projection 9K at an intermediate position, and further lowering is prevented. In this way, the positioning of the lead wire 73 and thus the noise preventing capacitor 71 in the height direction is performed.
[0174]
By providing the noise prevention capacitor 72 as described above, the configuration of the ignition circuit 41 in the circuit case 9 is as shown in FIG.
[0175]
By providing the noise prevention capacitor 71 in the circuit case 9 as described above, the following operation and effect can be obtained as compared with the related art.
[0176]
(1) In the conventional method, the noise prevention capacitor 71 is installed at the power supply ground point in the harness of the engine room separately from the ignition coil device (pencil coil) 21, but according to such an installation method, the noise of the ignition coil is reduced. Will get on the harness between the ignition coil device and the capacitor 71 and leak out of the ignition coil device. On the other hand, in the case of the method of the present invention, the distance from the noise source of the ignition coil to the capacitor 71 is extremely short. Prevents noise from leaking and enhances noise prevention performance.
[0177]
(2) In the conventional method, since the noise prevention capacitor 71 is provided in the harness of the engine room, if the capacitor 71 is installed in a naked state, there is a possibility that the capacitor 71 may be corroded by moisture, salt, or the like entering the engine room. It must be covered, which increases costs. In contrast, in the case of the method of the present invention, the encapsulation of the insulating resin 43 in the circuit case 9 also serves as the resin sealing of the capacitor 71. This need not be performed, and the cost of the capacitor 71 can be reduced accordingly.
[0178]
(3) In the conventional method, since the noise prevention capacitor 71 is provided in the harness of the engine room, the man-hour of the harness in the engine room increases. In the case of the present invention, the installation work of the noise prevention capacitor 71 on such a harness. When the ignition coil device 21 is mounted in the engine room, the noise prevention capacitor 71 is also naturally installed, so that the load of parts mounting work in the engine room for assembling a car can be reduced.
[0179]
In this embodiment, the shape of the secondary bobbin head 2A is cylindrical as shown in FIGS. 22 and 23, and the engaging portions 2D 'which engage with the detents of the winding machine are arranged in parallel. It consisted of a pair of projection pieces. The detent on the winding machine side is in the form of a single pin (not shown) sandwiched between the pair of protrusions.
[0180]
Most of the spring 13 in the ignition coil device 21 is connected to the high-voltage terminal 12 at one end (upper end) of the spring 13 when one end (upper end) of the spring 13 enters the cylindrical wall 6 ′ of the coil case 6. The lower end of 13 (one end opposite to the high-voltage terminal 12) is made to project outside the lower end of the coil case 6 at least before coupling with the ignition plug 22. For this purpose, the length of the cylindrical wall 6 'at one end of the coil case 6 is relatively shorter than that of the spring 13 in the first embodiment (FIG. 1).
[0181]
According to such an embodiment, the spark plug 22 is not substantially connected (connected) to the lower end of the spring 13 in the coil case one end cylindrical wall 6 '(in this regard, in the first embodiment, the spark plug 22 is A substantially upper half portion is introduced into the coil case one end wall 6 ′ and connected to the lower end of the spring 13), a position at substantially the same level as the lower end opening of the tube wall 6 ′, or a position below the lower end (the tube). At a position outside the wall 6 '). Therefore, in order to compensate for the shortening of the cylindrical wall 6 ', the lower side of the lower end of the cylindrical wall 6' is made longer than that of the type of the first embodiment so as to compensate for the shortening of the cylindrical wall 6 '. A substantially sealing connection can be made below the wall 6 '.
[0182]
According to the above configuration, even if there is a relative inclination θ between the axes of the ignition plug 22 and the ignition coil device 21 as shown in FIG. 25, the ignition plug 22 interferes with the coil case cylinder wall 6 ′. Therefore, the ignition coil device 21 and the ignition plug 22 can be flexibly sealed and connected by utilizing the flexibility of the rubber boot 14.
[0183]
According to this embodiment, even when the spark plug 22 and the plug hole 23B are installed at an angle θ in the engine as shown in FIG. 25, the ignition coil device 21 is aligned with the axis of the spark plug 22. It can be guided into the guide tube 21 and the plug hole 23 and coupled to the spark plug 22 without causing the ignition plug 22 and the ignition coil device 21 to be coupled with an inclination θ due to the installation space of the automobile parts. If this is the case, it can be realized without any difference from the conventional pencil coil mounting operation.
[0184]
This type of conventional ignition coil device (pencil coil) is of a type in which the axis of the ignition plug is aligned with the axis of the ignition plug, and the ignition coil device is angled with respect to the ignition plug 22 as described above. No consideration was given to joining.
[0185]
The rubber boot 14 has a function of preventing the following creeping discharge. That is, when the ignition coil device 21 is set in the plug hole 23B, the high-voltage terminal 12 of the ignition coil device 21 is located near the plug hole 23B, but the plug hole 23B is grounded. If a crack or the like occurs in the portion, there is a possibility that creeping discharge may occur via the crack and the cylindrical wall 6 'between the high voltage terminal 12 and the plug hole 23B. When the rubber boot 14 is attached to the cylinder wall 6 ', the contact distance L between the cylinder wall 6' and the rubber boot 14 is substantially added to the distance between the high voltage terminal 12 and the plug hole 23B, so that the contact distance L is kept long. This can prevent the creeping discharge. In the present embodiment, the distance from the position of the high-voltage terminal 12 in the lower end cylindrical wall 6 ′ of the coil case to the lowermost end of the coil case cylindrical wall 6 ′ is shortened. Is extended from the lowermost end of the cylindrical wall 6 'to the vicinity of the center core 7 to secure a distance for preventing the above-described creeping discharge. That is, the rubber boot 14 extends the portion facing the outer surface of the cylindrical wall 6 ′ longer than the portion facing the inner surface of the cylindrical wall 6 ′ to secure a longer total creeping discharge prevention distance. ing.
[0186]
In this embodiment, as described above, in order to bring the lower end of the spring 13 below the lower end opening of the coil case 6, as a method of shortening the cylindrical wall 6 ′ below the coil case 6, Alternatively, the length of the high voltage terminal 12 housed in the cylindrical wall 6 ′ in the axial direction of the coil case may be extended to near the lower end opening position of the coil case 6 (in other words, the spring of the high voltage terminal 12 The high-voltage terminal 12 is extended downward to a position where the length of the spring 13 is longer than the distance from the place where the coil 13 is received to the lowermost end of the coil case 6). Can also be taken out (below). By adjusting the length (length) of the spring 13 from the lower end opening of the coil case 6 by adjusting the length of the high-voltage terminal 12 in this manner, the ignition coil device 21 can be moved in accordance with the relative inclination θ of the ignition plug 22. It can be appropriately connected to the spark plug (connection via the flexible boot 14).
[0187]
In the present embodiment, as shown in FIG. 25, an O-ring 91 is fitted into an annular groove 90 provided on the lower surface of the circuit case 9, and the ignition coil The device 21 is directly installed.
[0188]
A recess 95 is provided in the circuit case 9 to reduce the substantial thickness of the circuit case 9 to prevent sinking during resin molding.
[0189]
In the present embodiment, the same operation and effect as those of the first embodiment can be obtained.
[0190]
Further, the arrangement and configuration of the above-described noise prevention capacitor 71 (circuit case interior type) and the shape and structure of the rubber boot 14 can also be applied to an ignition coil device in which a primary coil is disposed inside and a secondary coil is disposed outside. .
[0191]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in the ignition coil for internal combustion engines of the independent ignition type of the internal secondary coil structure and the insulating resin injection hardening system in the coil case, the so-called pencil mounted in the plug hole while improving the thermal shock resistance and insulation performance. It is possible to satisfy the demand for the reduction in diameter of the coil type (thin cylindrical ignition coil device).
[Brief description of the drawings]
FIG. 1 is a vertical cross-sectional view (a cross-sectional view taken along the line BB ′ in FIG. 3) of an ignition coil device according to a first embodiment of the present invention, and an enlarged cross-sectional view of a part of FIG.
FIG. 2 is a sectional view taken along line AA ′ of FIG. 2;
FIG. 3 is a diagram of the ignition coil device of FIG. 1 as viewed from above, showing the inside of a circuit case in a state before resin filling;
FIG. 4 is an ignition circuit diagram used in the embodiment.
FIG. 5 is an explanatory diagram showing a state in which the ignition coil device according to the embodiment is attached to an engine.
FIG. 6 is a cross-sectional view schematically showing an internal structure of a secondary bobbin that stores a center core.
FIG. 7 is an explanatory diagram showing a mechanism of generating electrostatic stray capacitance of the ignition coil device.
FIG. 8 is an explanatory diagram showing potentials of a secondary coil and a center core.
9A is a circuit diagram showing the principle of an ignition coil device, FIG. 9B is an explanatory view showing the principle of manufacturing an ignition coil according to the present invention, and FIG. 9C is an explanatory view showing the principle of manufacturing a conventional ignition coil.
FIG. 10 is a partial perspective view of a secondary bobbin used in the first embodiment.
FIG. 11 is a partial perspective view showing a combination state of a primary bobbin and a secondary bobbin used in the first embodiment.
FIG. 12 is an explanatory diagram showing a positional relationship between an ignition coil set and a circuit unit used in the first embodiment.
FIG. 13 is a partial perspective view showing a state where the secondary bobbin of the first embodiment is inserted into the primary bobbin.
14A is a bottom view of the primary bobbin of the first embodiment, FIG. 14B is a bottom view of the secondary bobbin, FIG. 14C is a cross-sectional view taken along the line CC ′ of FIG. () Is a bottom view showing the state of the combination of the primary bobbin and the secondary bobbin.
FIG. 15 is a sectional view of a coil case used in the first embodiment.
FIG. 16 is an explanatory view showing a manufacturing process of the ignition coil device.
FIG. 17 is an explanatory view showing a production example of the ignition coil device.
FIG. 18 is an explanatory diagram showing an example of mounting a rotary shaft of a winding machine, a primary bobbin, and a secondary bobbin.
FIG. 19 is an explanatory view showing a state in which the rotary shaft in a state where the secondary bobbin is inserted is removed from the motor of the winding machine.
FIG. 20 is a sectional view of a main part of the ignition coil device according to the second embodiment of the present invention (a sectional view taken along line DD ′ in FIG. 21);
FIG. 21 is a view of the ignition coil device as viewed from above, showing the inside of the circuit case in a state before filling with resin.
FIG. 22 is a partial perspective view of a secondary bobbin used in the second embodiment.
FIG. 23 is a partial perspective view showing a combined state of a primary bobbin and a secondary bobbin used in the second embodiment.
FIG. 24 is an ignition circuit diagram used in the second embodiment.
FIG. 25 is an explanatory view showing a mounted state of the ignition coil device of the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Center core, 2 ... Secondary bobbin, 2A ... Secondary bobbin head, 3 ... Secondary coil, 4 ... Primary bobbin, 5 ... Primary coil, 6 ... Coil case, 7 ... Center core, 8 ... Insulating resin, 9 ... Circuit case, 9B ... Connector housing, 17 ... Soft epoxy resin, 17 '... Pressurized recess on resin surface, 18 ... Primary / secondary coil combined terminal, 19 ... Primary coil terminal, 31, 33, 33 ... Connector terminal, 32, 34, 36: lead-out terminals (lead terminals), 37: metal base, 39: ignition control drive element, 40: ignition circuit unit.

Claims (2)

An elongated center core serving as a magnetic circuit of an ignition coil is held in a bottomed cylindrical secondary bobbin around which a secondary coil is wound, and a cylindrical primary bobbin around which a primary coil is wound outside the secondary bobbin. Are disposed in an elongated cylindrical coil case, and an igniter case for storing an ignition circuit unit is provided at one end of the cylindrical coil case, and the ignition circuit unit includes the secondary bobbin. An ignition coil for an internal combustion engine, which is disposed on a surface of one end opening through a base holding the ignition circuit unit,
A magnet and a rubber are arranged so as to overlap between one end of the center core and the bottom of the secondary bobbin, and another magnet is arranged at the other end of the center core. Covered with a thin elastic insulating layer consisting of soft epoxy, silicone rubber, or silicone gel,
The coil case and the igniter case are filled with an insulating resin harder than the elastic insulating layer and solidified to hold between the coil case and the primary coil, between the primary bobbin and the secondary coil, and the ignition circuit unit. An ignition coil for an internal combustion engine , wherein the hard insulating resin is filled between the base and the elastic insulating layer . 2. The ignition coil according to claim 1, wherein the insulating resin harder than the elastic insulating layer is an epoxy resin .

Images