JP3596488B2 - Ignition coil for internal combustion engine - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an ignition coil for an internal combustion engine.
[0002]
[Prior art]
Conventionally, in an ignition coil as disclosed in Japanese Patent No. 2830416, a connector electrically connected to a primary coil and a high-pressure tower for supplying a high voltage from a secondary coil to the outside are arranged in the same direction from a casting material. It is provided so as to protrude.
[0003]
[Problems to be solved by the invention]
However, the positional relationship is not always such, and the connector and the high-pressure tower may have to be provided at opposite positions. In an ignition coil having a primary coil and a secondary coil in a case, it is necessary to put a casting material in the case to insulate the high voltage generated by the secondary coil. In that arrangement, it is not shown how the connector and the high-pressure tower should be located opposite to each other for a case with a bottom and an opening.
[0004]
Also, when the casting material shrinks due to heat, it is necessary to keep the high voltage of the high voltage terminal inside even if the casting material peels off from the high voltage terminal, as disclosed in Japanese Patent No. 2830416. In such an ignition coil, a high-pressure tower is provided at the opening of the case, and when the casting material is peeled off from the high-voltage terminal, it is difficult to keep a high voltage inside the ignition coil.
[0005]
Therefore, an object of the present invention is to provide an ignition coil for an internal combustion engine that can keep a high voltage of a high voltage terminal inside even when the casting material is peeled from a high voltage terminal when the casting material contracts due to heat. And
[0006]
[Means for Solving the Problems]
Therefore, the present invention provides a primary coil,
A secondary coil,
A resin coil case that houses the primary coil and the secondary coil and has one end open and the other end having a bottom;
A casting material injected into the coil case to fix the primary coil and the secondary coil;
A high-pressure tower that outputs a voltage generated by the secondary coil and that is formed in a cylindrical shape at the bottom portion;
A high-voltage terminal disposed in the high-voltage tower and supplied with a high voltage from the secondary coil;
The high-pressure tower is formed to protrude outward from the coil case and has a hollow high-pressure tower outer resin portion having an opening at a tip thereof, and the high-pressure tower outer resin portion inward from the opening side of the high-pressure tower outer resin portion. A high-pressure tower inner resin portion that extends through a gap between the high-pressure terminal and the outer peripheral portion of at least the connection-side end of the high-voltage terminal, and a casting material exceeds the connection-side end in the gap. The present invention provides an ignition coil for an internal combustion engine, which is filled to the maximum.
[0007]
[Action]
According to the first aspect of the present invention, the high-pressure tower is formed into a cylindrical shape at the bottom, and the resin portion inside the high-pressure tower covers the outer periphery of the connection-side end, and the casting material is filled to a point beyond the connection-side end of the high-voltage terminal. Therefore, it is possible to increase the creepage distance along the casting material, and it is possible to prevent high voltage from leaking to the outside even if the casting material is peeled off from the high voltage terminal by heat.
[0008]
According to the second aspect of the present invention, even if a crack occurs in the resin portion inside the high-pressure tower from the corner of the high-voltage terminal, the extension can be stopped by the casting material in the gap.
[0009]
【Example】
First, the configuration of an ignition coil for an internal combustion engine used in this embodiment will be described with reference to FIGS.
[0010]
As shown in FIGS. 4 and 5, the primary spool 1 made of resin is provided inside a primary spool body 1 a of a hollow quadrangular prism with rounded corners and slightly inside both ends of the primary spool body 1 a. And first and second flanges 1b and 1c projecting in the outer peripheral direction. The first flange 1b is provided with a fitting projection 1d that protrudes over the entire circumference in the axial direction toward the outer end. As shown in FIG. 2, first and second positioning portions 1 e for determining a position when the primary spool 1 and the secondary spool 2 made of resin are fitted to each other at the outer peripheral facing portion of the second flange 1 c. , 1i are provided to protrude radially outward.
[0011]
The first positioning portion 1e is built up to the end of the primary spool main body 1a to form a gate built-up portion 1f. On the second positioning portion 1i side, a T-shaped protrusion 1g is provided from the second flange 1c toward the outside in the axial direction, and the first spool main body 1a is connected to the second flange 1c on the surface. A fitting groove 1h is dug radially inward to the tip.
[0012]
One side of the resin coil case 3 is opened, and the outer periphery of one end of the primary spool 1 is fitted on the bottom side of the other side, and a through hole 3a is provided. As shown in FIG. 3, a first inwardly protruding portion 3 b protruding inward in the axial direction is formed around the through hole 3 a in the inner bottom portion of the coil case 3, and a first flange of the primary spool 1 is further formed. A second inwardly protruding portion 3c is formed to protrude inward in the axial direction from the coil case 3 so as to sandwich the fitting protrusion 1d provided on the first inwardly protruding portion 3b. Further, an outer protruding portion 3d protruding axially outward along the through hole 3a is formed around the through hole 3a in the outer bottom portion of the coil case 3.
[0013]
The length from the first flange 1b to the outer end of the primary spool 1 is substantially the same as the combined length of the outer protrusion 3d of the coil case 3 and the first inner protrusion. .
[0014]
Further, as shown in FIG. 3, a radial projection 3e is formed in the through hole 3a of the coil case 3 so as to project radially inward so as to go around the inner periphery of the through hole 3a. The inner diameter of the radial projection 3e is set to be slightly shorter than the outer diameter of the primary spool 1 at a portion fitted into the through hole 3a of the coil case 3. That is, when the outer periphery of one end of the primary spool 1 is fitted into the through hole 3a of the coil case 3, the radial projection 3e is crushed, and the fitting portion between the coil case 3 and the primary spool 1 is sealed. It has such a structure. Thereby, even if the fitting between the primary spool 1 and the through hole 3a of the coil case 3 is slightly shifted in the axial direction, the reliability of the radial seal is not impaired.
[0015]
The shape of the first magnetic core 4 is such that a center magnetic path portion 4a extending from a center portion in the hollow portion of the primary spool 1 to the case fitting side in the axial direction and a radial direction from an end portion of the center magnetic path portion 4a on the case fitting side. A radial magnetic path portion 4b extending outward and an outer peripheral magnetic path portion 4c extending axially from the radially outer end of the radial magnetic path portion 4b to near the opening of the coil case, have a J-shape. ing. The outer peripheral magnetic path 4c is provided with a fitting projection 4d.
[0016]
Further, the shape of the second magnetic core 5 is such that a center magnetic path portion 5a extending from the center portion in the hollow portion of the primary spool 1 to the case opening side in the axial direction and a radial direction from the end portion of the center magnetic path portion 5a on the case opening side. It has an L-shaped radial magnetic path 5b extending outward and an outer magnetic path 5c slightly extending from the radially outer end of the radial magnetic path 5b toward the axial case fitting side. . The outer peripheral magnetic path 5c is provided with a fitting recess 5d. The first and second magnetic cores 4 and 5 are fitted with fitting projections 4d and recesses 5d provided in the respective outer peripheral magnetic path portions to form a square-shaped magnetic circuit. A gap 13 is formed on the opposing surface of each of the center magnetic path portions 4a, 5a.
[0017]
The length of the center magnetic path portions 4a and 5a including the gap 13 of the magnetic circuit is 0 from the length from the tip of the outwardly protruding portion 3d of the coil case 3 to the tip of the primary spool 1 on the case opening side. .2 mm. This margin is provided even when the assembly of the primary spool 1 and the coil case 3 is slightly inclined with respect to the axial direction, even if the first and second magnetic cores 4 and 5 are fitted to each other. This is because the fitting in the recess 4d and the recess 5d can be performed without a gap.
[0018]
The secondary spool 2 has a primary spool through-hole through which the primary spool 1 can penetrate, and a plurality of radially extending flanges 2a are arranged in the outer peripheral portion in the axial direction at intervals. In. First and second metal fittings for fixing first and second coil connection fittings 2b and 2f for electrically connecting the ends of the primary and secondary coils 9 and 11 to both ends of the secondary spool 2. Parts 2c and 2g are formed. Also, at one end of the secondary spool 2, first and second primary spool fitting recesses 2d and 2e into which the first and second positioning portions 1e and 1i of the primary spool 1 fit are provided around the through hole. is there. A secondary coil 11 is wound separately on the outer periphery of the secondary spool 2 partitioned by each flange 2a.
[0019]
The connector 8 is fitted to the primary spool 1 configured as described above, and the primary coil 9 is wound. The primary spool 1 is fitted to a secondary spool 2 around which a secondary coil is wound with the first and second positioning portions 1e and 1i together to form a coil body. Further, while fitting one end of the primary spool 1 into the through hole 3a of the coil case 3, the fitting projection 1d of the primary spool 1 is connected to the first and second inwardly protruding portions 3b, 3c of the coil case 3. The coil body is assembled in the coil case 3 by fitting in between.
[0020]
After that, the center magnetic path portions 4a and 4b of the first and second magnetic cores 4 and 5 are inserted into the hollow portion of the primary spool 1, and the fitting protrusions on the outer peripheral magnetic path portions 4c and 5c of the assembly are provided. The portion 4d and the recess 5d are press-fitted and fitted. At this time, the first magnetic core 4 and the second magnetic core 5 are fixed to each other by bonding the joining portion on the gap 13 side in the hollow portion of the primary spool 1 with an adhesive. By the assembly of the first and second magnetic cores, the outwardly projecting portion 3d of the coil case 3 and the other end of the primary spool 1 are connected to the pair of radial magnetic poles of the first and second magnetic cores 4 and 5. The first protrusions 1d provided on the first flange 1b of the primary spool 1 and the first protrusions provided on the coil case 3 are in contact with the road portions 4b and 5b or opposed through a small gap. The axial movement of the fitting with the second two inwardly protruding portions 3b, 3c is restricted.
[0021]
Thereby, it is possible to seal between the first and second inwardly protruding portions 3b, 3c of the coil case 3 and the fitting protrusion 1d of the primary spool 1, and the casting material 6 is injected into the coil case 3. When this is done, it is possible to prevent resin leakage. In addition, by combining this with the above-described sealing by the radial projection 3e to form a double sealing structure, resin leakage can be reliably prevented.
[0022]
Further, as shown in FIG. 1, the fitting position of the first and second magnetic cores 4 and 5 is set such that the axial dimension of the outer magnetic path portion 4c of the first magnetic core 4 is L1, When the axial dimension of the outer peripheral magnetic path portion 5c of the magnetic core 5 is L2, L1≫L2 is set. Then, the resonance frequency of the first magnetic core 4 becomes lower than the resonance frequency of the magnetic core 5 due to the change in shape and weight. Therefore, since the resonance frequency of the first and second magnetic cores 4 and 5 can be changed, no resonance phenomenon occurs, and the expansion of the magnetic sound due to this can be prevented. Therefore, it is not necessary to weld the fitting portions of the first and second magnetic cores 4 and 5 to reduce the magnetic noise, and it is not necessary to mount the magnetic cores 4 and 5 via rubber between the contact surfaces when the fitting portions are attached. It can be assembled only by simple fitting.
[0023]
In addition, the first positioning portion 1e of the primary spool 1 was built up outward in the axial direction, and a gate build-up portion 1f was formed on the end face of the product for hot runner molding. This is because the shape of the runner 7 has a mortar-shaped tip as shown in FIG. 4 because the heater is disposed in the runner 7. When the gate 7a for injecting the material for forming the spool 1 is to be brought, the gate 7a for injecting the material is set in the first positioning portion 1e because the mortar portion hits the end of the primary spool 1. Because he couldn't. Here, the hot runner molding means that the mold of the runner 7 remaining during the cold runner molding can be eliminated by pouring the molding resin using the runner 7 with a heater, and further, after the primary spool 1 is molded. The step of separating the mold of the runner 7 can be reduced. As shown in FIG. 5, the resin connector 8 is provided with a T-shaped recess 8a corresponding to the T-shaped protrusion 1g provided on the primary spool 1 so as to be fitted. I have. Further, on the surface of the bottom surface of the fitting portion that comes into contact with the primary spool main body 1a, a fitting protrusion 8b is provided so as to fit into the fitting groove 1h provided in the primary spool 1. By providing the fitting portion, the casting material 6 is poured into the coil case 3 after being assembled to the primary spool 1 and the primary spool 1 and the connector are connected to the primary spool 1 in any direction until the solidification occurs. 8 can be prevented from loosening.
[0024]
By providing this fitting portion, it is not necessary to increase the number of molds for molding the connector 8 and the primary spool 1, and the mold structure is not complicated. Further, an input terminal connecting portion 8c for connecting an external terminal of the connector 8 is open toward the case opening side, and two L-shaped fittings 8d are arranged side by side inside the input terminal connecting portion 8c. One end of the L-shaped fitting 8 d extends radially outward from the connector 8, and is electrically connected to the end of the primary coil 9. The other end extends inside the connector 8 toward the case opening side, and is electrically connected to an external terminal (not shown).
[0025]
The high-pressure tower 10 is integrally formed on the bottom side of the coil case 3 with a resin material forming the coil case 3. In the high-pressure tower 10, a high-voltage fitting 10a to which a high voltage is supplied from the secondary coil 11 is arranged.
[0026]
The high-pressure tower 10 is formed so as to protrude outward from the bottom of the coil case 3, and has a hollow high-pressure tower outer resin portion 10 b having an opening at the tip and an inner side from the opening side of the high-pressure tower outer resin portion 10 b. And a high-pressure tower inner resin portion 10c which extends through the gap between the high-pressure tower outer resin portion 10b and the outer peripheral portion of the connection side end 10aa with the outside of the high-pressure metal fitting 10a. I have. The gap between the high-pressure tower outer resin portion 10b and the high-pressure tower inner resin portion 10c extends to a point beyond the connection side end 10aa with the outside of the high-pressure metal fitting 10a. Has been injected.
[0027]
As shown in FIG. 6, the connection between the high-voltage tower 10 and the external terminal is sealed by a rubber cap 12a covering the connection between the high-voltage cord 12 and the high-pressure tower 10 on the outer periphery of the high-pressure tower 10. It is.
[0028]
Further, instead of FIG. 6, the inner circumference of the high-pressure tower 10 is sealed by a rubber 12b covering the connection between the high-voltage cord 12 and the high-pressure tower 10 as shown in FIG. The connection portion may be fixed by the holder 12c so that the connection portion does not exist. Further, the high-pressure tower 10 may be separate from the coil case 3.
[0029]
The other end of the high-pressure cord 12 is connected to a spark plug of each cylinder via a distributor (not shown). In the case without a distributor, it is directly connected to an unillustrated ignition plug.
[0030]
Further, as another embodiment, the present invention is applied to an ignition coil in which a permanent magnet is inserted into a portion where the first and second magnetic cores 4 and 5 are joined to each other on the tip magnetic pole surface in the inner peripheral opening of the primary spool. Is also good. Further, the shape of the magnetic core may be a day-shaped shape obtained by combining two E-shaped ones. In addition, the radial projecting portion 3e provided on the coil case 3 does not necessarily need to be provided on the coil case 3, and the primary spool 1 is provided with a radial projecting portion around the entire periphery of the contact portion with the through hole 3a of the coil case 3. A radial projection may be provided inward.
[0031]
With the above configuration, according to the present embodiment, after the primary spool and the coil case are fitted, the magnetic core is assembled, so that the coil is provided in the through hole of the coil case toward the outside in the axial direction. The outer protruding portion and the other end of the primary spool are suppressed by the radial magnetic path portions of the plurality of magnetic cores, so that the axial movement of the fitting portion between the primary spool and the coil case is limited. . As a result, the fitting portion can be prevented from being inclined or coming out before the casting material is injected into the coil case and hardened, so that the seal between the coil case and the primary spool can be reliably performed. it can. Further, since the distance between the magnetic core and the secondary coil can be increased by the length of the outwardly protruding portion, it is possible to prevent the voltage from leaking from the high voltage portion of the secondary coil to the magnetic core.
[0032]
Furthermore, when the primary spool and the coil case are fitted together, even if the fitting is inclined, a radial projection provided in the radial direction of the fitting portion is provided on at least one of the primary spool and the coil case. The seal can be reliably performed only by changing the position where the portion is collapsed. Thus, by combining the above-described seal and this seal, a double seal structure can be obtained, and resin leakage when the casting material mainly composed of epoxy resin is poured can be prevented.
[0033]
In addition, by pouring the casting material between the high-pressure tower molding resin part and the coil case molding resin part from the external connection side end of the high-pressure metal fitting to the outside, and solidifying, the external material along the high-pressure tower molding resin part from the high-pressure metal fitting is formed. The creepage distance up to can be increased. Thereby, even if the casting material is separated from the high-pressure tower molding resin portion due to thermal distortion, it is possible to prevent the high voltage of the high-pressure fitting from leaking to the outside along the separated surface. Further, cracks generated in the high-pressure tower molding resin from the corners of the high-pressure metal fitting can be prevented from progressing by the casting material filled between the coil case and the high-pressure tower molding resin.
[0034]
In addition, the gate positioning portion is formed by building up the fitting positioning portion with the secondary spool, so that the gate mounting portion can be set on the end face of the product, and hot runner molding can be performed. As a result, the mold of the runner does not remain after the molding, and it is not necessary to use an extra material, and the step of cutting the mold of the runner remaining in the product can be reduced.
[0035]
Furthermore, by largely shifting the fitting position of the outer peripheral magnetic path between the magnetic cores to one side, magnetic noise due to resonance can be prevented. Accordingly, when the magnetic cores are welded to each other or when the ignition coil is mounted, it is not necessary to interpose rubber between the magnetic core and the mounting surface. Thereby, a significant cost reduction can be achieved.
[0036]
In addition, by providing a fitting portion in the radial direction on the surface that comes into contact when the primary spool and the connector are fitted, some force is applied in the axial direction after the connector is fitted to the primary spool. It is possible to prevent the user from falling off. Thus, it is possible to prevent the fitting from being loosened during the process until the casting material is hardened.
[Brief description of the drawings]
FIG. 1 is a side sectional view when the present invention is used for an ignition coil for an internal combustion engine.
FIG. 2 is a front view showing the fitting of a primary spool and a secondary spool when the present invention is used for an ignition coil for an internal combustion engine.
FIG. 3 is an enlarged cross-sectional view near a through hole of a coil case when the present invention is used for an ignition coil for an internal combustion engine.
FIG. 4 is a side view of the primary spool.
FIGS. 5A and 5B are perspective views showing how a primary spool and a connector are fitted when the present invention is used for an ignition coil for an internal combustion engine.
FIG. 6 is a cross-sectional view showing a connection between an external terminal and a high-pressure tower which is sealed outside when the present invention is used for an ignition coil for an internal combustion engine.
FIG. 7 is a cross-sectional view showing a connection between an external terminal and a high-pressure tower that seals inside when the present invention is used for an ignition coil for an internal combustion engine.
[Explanation of symbols]
1 Primary Spool 1e First Positioning Portion 1f Gate Overlay Portion 1h Fitting Groove 1i Second Positioning Portion 2 Secondary Spool 3 Coil Case 3a Through Hole 3d Outer Projection 3e Radial Projection 4 First Magnetic core 4a Central magnetic path 4b Radial magnetic path 4c Outer magnetic path 5 Second magnetic core 5a Central magnetic path 5b Radial magnetic path 5c Outer magnetic path 6 Casting material 8 Connector 8b Fitting protrusion 8d L-shaped fitting 9 Primary coil 10 High-pressure tower 10a High-pressure fitting 10aa Connection end 10b High-pressure tower outer resin part 10c High-pressure tower inner resin part 11 Secondary coil

Claims (2)

A primary coil,
A secondary coil,
A resin coil case that houses the primary coil and the secondary coil and has one end open and the other end having a bottom;
A casting material injected into the coil case to fix the primary coil and the secondary coil;
A high-pressure tower that outputs a voltage generated by the secondary coil and that is formed in a cylindrical shape at the bottom portion;
A high-voltage terminal disposed in the high-voltage tower and supplied with a high voltage from the secondary coil;
The high-pressure tower is formed to protrude outward from the coil case and has a hollow high-pressure tower outer resin portion having an opening at a tip thereof, and the high-pressure tower outer resin portion inward from the opening side of the high-pressure tower outer resin portion. A high-pressure tower inner resin portion provided in contact with the connection side end of the high-voltage terminal, with a casting material exceeding the connection side end in the gap. An ignition coil for an internal combustion engine, which is filled to the point. The ignition coil for an internal combustion engine according to claim 1, wherein the resin part inside the high-pressure tower covers an outer peripheral portion of the connection-side end.

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