JP3713642B2 - Engine ignition coil device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an ignition coil device for a direct plug type engine.
[0002]
[Prior art]
Conventionally, a coil unit in which a primary coil bobbin is mounted in a hollow shaft of a secondary coil bobbin and a rod-shaped core is inserted in the hollow shaft of a primary coil bobbin is placed in a cylindrical coil case, and is insulated internally. There is an ignition coil device for a spark plug direct attachment type engine in which resin is injected and solidified and integrally molded, and an ignition plug is connected to a high-pressure terminal provided in a lower portion of the coil case (Japanese Patent Application Laid-Open No. 2003-260260) (See Sho 60-10781).
[0003]
In such a conventional engine ignition coil device, when the primary coil bobbin is mounted in the hollow shaft of the secondary coil bobbin, the flange of the primary coil bobbin is in contact with the inner wall of the hollow shaft of the secondary coil bobbin. The center positioning of the primary coil bobbin placed in the hollow shaft of the secondary coil bobbin is performed.
[0004]
Further, when the coil unit is put into the coil case, the center of the coil unit to be put into the coil case is positioned so that the hook of the secondary coil bobbin is in contact with the inner wall of the coil case.
[0005]
[Problems to be solved by the invention]
The problem to be solved is that, in the case of an ignition coil device for a spark plug direct attachment type engine, since it is embedded in a hole formed in the cylinder head portion of the engine and attached to the spark plug, Therefore, a thermal stress with a large axial contraction difference is applied to the resin in the coil case, so that the primary coil bobbin and the secondary coil bobbin are cracked.
[0006]
In particular, in the coil bobbin on the secondary side, since the flange is provided close to the high voltage portion at the end of the secondary coil, there is a problem that current leakage occurs on the coil case side through the flange. There is.
[0007]
[Means for Solving the Problems]
The present invention relates to an ignition coil device for a spark plug direct attachment type engine, in which a coil bobbin flaw is destroyed by a thermal stress having a large axial contraction difference applied to a resin in a coil case, or a secondary coil bobbin In order to prevent current leakage from occurring on the coil case side through the high voltage side flange, the coil bobbin flange on both the primary and secondary sides has been abolished and the secondary coil bobbin The center positioning of the primary side coil bobbin placed in the hollow shaft and the center positioning of the coil unit placed in the coil case can be performed.
[0008]
Therefore, in the present invention, the rib that supports the end portion of the primary coil bobbin having no wrinkles is formed so as to protrude to the inside of the secondary side coil bobbin, and the end portion of the primary side coil bobbin that is inserted into the hollow shaft of the secondary side coil bobbin is formed. By supporting with the rib, the center positioning of the primary coil bobbin placed in the hollow shaft of the secondary coil bobbin is performed.
[0009]
In addition, the present invention provides a centering of the secondary coil bobbin placed in the coil case by providing a protrusion that contacts the inner wall of the coil case at a location where the terminal end of the secondary coil of the secondary coil bobbin having no wrinkles is separated. I try to make it.
[0010]
【Example】
FIG. 1 shows an example of a configuration of an ignition coil device for a spark plug direct-attached engine, which includes a cylindrical coil case 1 in which a coil unit is placed, and a portion below the coil case 1. The plug cover 2 is inserted into the opening and attached to the opening, and the low-voltage terminal socket 3 is attached to the outside of the opening above the coil case 1.
[0011]
Inside the coil case 1, a coil bobbin 8 around which a secondary coil 7 is wound is coaxially mounted in a hollow shaft of a coil bobbin 6 around which a primary coil 5 is wound, and the coil bobbin 6 on the primary side is hollow. A coil unit having a rod-shaped core 9 inserted in the shaft is accommodated. Permanent magnets 10 are attached to both ends of the core 9 so that a large change in the amount of magnetic flux can be obtained when the primary current is interrupted.
[0012]
At the lower end of the coil bobbin 8 on the secondary side, a high voltage terminal mounting portion 11 is integrally formed so as to protrude from the central portion. A contact 13 for electrical connection with the spark plug 15 is attached to the high-voltage terminal 12 that is attached by being attached to the attachment portion 11.
[0013]
When the assembly comprising the primary side coil bobbin 6, the secondary side coil bobbin 8, the high voltage terminal 12 and the contact 13 is housed in the coil case 1, the contact 13 is formed in the central portion of the plug case 2. In a state of protruding outward from the tubular hole 4, the portion of the attachment portion 11 of the high voltage terminal 12 is press-fitted into the hole 4, and the assembly is positioned in the coil case 1 at a predetermined position. ing.
[0014]
Then, in a state where the assembly is positioned in the coil case 1 in a predetermined position, an insulating resin such as epoxy melted from the opening above the coil case 1 is injected, and the insulating resin is solidified. Are integrally formed.
[0015]
At this time, the permanent magnets 10 provided at both ends of the core 9 are respectively covered so that the insulating resin does not enter the core 9 portion, and relatively large thermal stress generated in the longitudinal direction of the core 9 is absorbed. A damper member 14 is provided for preventing the surrounding insulating resin from cracking.
[0016]
A plug rubber 16 that holds a spark plug 15 is attached to the tip of the plug cover 2. When the spark plug 15 is inserted into the plug cover 2, the tip of the spark plug 15 comes into contact with the contact spring 13 to be electrically connected.
[0017]
Further, an igniter 19 is housed in the low voltage terminal socket 3 as shown in FIG.
[0018]
In a state where the cap 20 is attached to the low voltage terminal socket 3, when the insulating resin is injected into the nozzle 20 through the hole 22 formed in the cap 20, the low voltage terminal socket 3 is provided inside the cap 20. Insulating resin is injected to such a level that the tips of the plurality of ribs 21 can be used, and the cap 20 is fixed integrally.
[0019]
It is effective that the plurality of ribs 21 provided on the cap 20 disperse the thermal stress applied to the insulating resin solidified as the temperature changes, and cracks are generated in the insulating resin portion above the igniter 19. Will be prevented.
[0020]
Then, with the coil case 1 embedded in the cylinder hole 231 provided in the cylinder head 23 of the engine, the bolt 26 passes through the bolt seat 25 formed integrally with the low-voltage terminal socket 3. This ignition coil unit is attached to the cylinder head 23 side.
[0021]
The coil case 1 is formed of a magnetic material such as a silicon steel plate having high conductivity and having a high conductivity. The coil case 1 and the ground terminal 27 in the low-voltage terminal socket 3 are electrically connected, and the coil case 1 is held at the ground potential.
[0022]
Thus, the coil case 1 exhibits an electromagnetic shielding effect, and the side core plays the role of concentrating most of the magnetic flux generated by the open magnetic circuit type coil unit on the coil case 1 part. It is effectively suppressed that the magnetic flux is demagnetized by passing through a portion of the surrounding engine cylinder block and the secondary output voltage is lowered.
[0023]
Further, since the coil case 1 is held at the ground potential, it is possible to prevent electric shock due to leakage discharge from the internal high voltage portion. And the corona discharge which generate | occur | produces locally between the secondary coil 7 and the coil case 1 is suppressed, and the insulation durability of the insulating resin interposed in the meantime improves.
[0024]
In addition, the electric discharge generated through the gap between the coil case 1 and the cylinder head 23 is eliminated, and it is possible to effectively prevent the electromagnetic interference in the engine control system and surrounding equipment.
[0025]
In addition, in order to suppress the eddy current loss in the coil case 1, as shown in FIG. 3, a gap is formed in the longitudinal direction of about 0.5 to 1.5 mm so as to have a C-shaped cross section. A slit 18 is provided.
[0026]
An elastic member 17 such as rubber or elastomer is provided inside the coil case 1.
[0027]
Thus, the elastic member 17 is interposed between the coil case 1 and the insulating resin injected and solidified therein, so that the thermal stress due to the temperature change is relieved by the elastic member 17 and the surroundings. The occurrence of cracks in the insulating resin is effectively prevented.
[0028]
In the ignition coil device for a spark plug direct-attached engine configured as described above, in the present invention, in particular, the primary coil bobbin 6 having no wrinkles at one end is used, and then the coil bobbin 6 is used. A rib 38 for supporting the end portion having no wrinkles is formed so as to protrude inside the coil bobbin 8 on the secondary side.
[0029]
Thus, the tip end portion of the primary coil bobbin 6 that is inserted into the hollow shaft of the secondary coil bobbin 8 is supported by the rib 38, and the primary coil bobbin 6 that is inserted into the hollow shaft of the secondary coil bobbin 8. The center positioning is performed.
[0030]
Further, in the present invention, as shown in FIG. 4, one having no wrinkles at one end of the secondary coil bobbin 8 is used. The secondary coil 7 wound around the coil bobbin 8 is turned into a bank winding in which the coil bobbin 8 is sequentially wound in the axial direction while being obliquely overlapped with the coil bobbin 8 at an angle θ (for example, 25 °). By gradually reducing the number of times, the slope winding is performed such that the coil diameter D decreases in the winding direction indicated by the arrow in the figure.
[0031]
Then, a protrusion 28 that abuts against the inner wall of the coil case 1 is provided at a position away from the terminal portion of the secondary coil 7 with no wrinkles in the coil bobbin 8 on the secondary side. The center of the secondary coil bobbin 8 is positioned.
[0032]
A plurality of projections 28 are provided at equal intervals on the same circumference of the coil bobbin 8 on the secondary side.
[0033]
Thus, by eliminating the wrinkles at at least one end of the primary side coil bobbin 6 and the secondary side coil bobbin 8, heat in which the axial shrinkage difference applied to the resin filled in the coil coil case 1 is large. The stress prevents the primary and secondary coil bobbins 6 and 8 from being destroyed.
[0034]
Then, even if the flange at one end of the primary coil bobbin 6 and the secondary coil bobbin 8 is abolished, the center positioning of the primary coil bobbin 6 put in the hollow shaft of the secondary coil bobbin 8 and The center positioning of the secondary coil bobbin 8 placed in the coil case 1 can be easily and reliably performed.
[0035]
Further, since there is no wrinkle that contacts the coil case 1 at a location close to the high voltage portion at the end of the secondary coil 7, current leakage occurs from the high voltage portion of the secondary coil 7 to the coil case 1 side. Nothing will happen. Therefore, it is possible to effectively prevent a decrease in secondary output voltage and deterioration of surrounding resin.
[0036]
This is because it is difficult to obtain sufficient insulation by thickening the resin layer in the coil case 1 due to the restriction of the diameter of the coil case 1 embedded in the cylinder hole 231, particularly in the high-pressure part. This is advantageous in a spark plug device directly attached to a spark plug that is insufficiently insulated.
[0037]
The protrusion 28 may be provided in a bowl shape from the viewpoint of preventing leakage from the high-pressure portion without considering the destruction of the secondary coil bobbin 8 due to thermal stress having a large axial shrinkage difference.
[0038]
【effect】
As described above, according to the ignition coil device for an engine according to the present invention, the rib that directly supports the end of the primary coil bobbin without a ridge is formed so as to protrude to the inside of the secondary coil bobbin. The center portion of the primary coil bobbin placed in the hollow shaft of the secondary coil bobbin is positioned by supporting the end portion of the primary coil bobbin placed in the hollow shaft of the secondary coil bobbin by the rib. Therefore, it is possible to effectively prevent the primary side coil bobbin from being destroyed by a thermal stress that has a large axial shrinkage difference applied to the resin in the coil case, and the primary side that is put into the hollow shaft of the secondary side coil bobbin. The center positioning of the side coil bobbin can be performed easily and reliably.
[0039]
Further, according to the present invention, in the ignition coil device of the spark plug direct attachment type engine, the protrusion that contacts the inner wall of the coil case at a position away from the terminal end portion of the secondary coil of the secondary coil bobbin without any wrinkles The secondary coil bobbin placed in the coil case is positioned at the center, so the secondary coil bobbin is destroyed by thermal stress that has a large axial shrinkage difference applied to the resin in the coil case. Can be effectively prevented. In addition, current leakage from the high voltage side of the secondary coil bobbin to the coil case side can be prevented, and the center positioning of the coil unit placed in the coil case can be easily and reliably performed. .
[Brief description of the drawings]
FIG. 1 is a front sectional view showing an ignition coil device for an engine according to an embodiment of the present invention.
FIG. 2 is a plan view showing an internal structure of a low voltage terminal socket in the embodiment.
FIG. 3 is a cross-sectional view of a coil case portion in the same embodiment.
FIG. 4 is a front sectional view showing a secondary coil bobbin in which one of the hooks around which a secondary coil employing bank winding and slope winding is wound is abolished.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coil case 2 Plug cover 3 Low voltage terminal socket 5 Primary coil 6 Primary coil bobbin 7 Secondary coil 8 Secondary coil bobbin 9 Core 15 Spark plug 38 Center positioning rib 28 Center positioning protrusion

Claims (4)

A coil unit in which a primary coil bobbin is mounted in the hollow shaft of the secondary coil bobbin and a rod-shaped core is inserted in the hollow shaft of the primary coil bobbin is placed in a cylindrical coil case, and an opening below the coil case Attaching a plug cover to the part, injecting an insulating resin inside, integrally molding it, embedding it in a cylinder hole formed in the cylinder head part of the engine and attaching it directly to the ignition plug In the coil device, a rib that supports the end of the primary coil bobbin having no wrinkles is formed so as to protrude inside the secondary coil bobbin, and the end of the primary coil bobbin that is put in the hollow shaft of the secondary coil bobbin is formed on the rib. The center position of the primary side coil bobbin placed in the hollow shaft of the secondary side coil bobbin is made to be supported by Ignition coil device for an engine, wherein the door. A coil unit in which a primary coil bobbin is mounted in the hollow shaft of the secondary coil bobbin and a rod-shaped core is inserted in the hollow shaft of the primary coil bobbin is placed in a cylindrical coil case, and an opening below the coil case Ignition of the engine that is attached to the part, injecting insulating resin into the inside, integrally molded, and installed in the cylinder hole formed in the cylinder head part of the engine and directly attached to the spark plug In the coil device, a protrusion that abuts on the inner wall of the coil case is provided at a location away from the terminal end of the secondary coil of the secondary coil bobbin without any wrinkles so that the center of the coil unit placed in the coil case can be positioned. An ignition coil device for an engine. 2. The ignition coil device for an engine according to claim 2, wherein a plurality of protrusions are provided on the circumference of the secondary coil bobbin. The ignition coil device for an engine according to the second aspect, wherein the secondary coil bobbin is provided with a projection in a hook shape.

Images