JPH0128650Y2 - - Google Patents

Description

[Detailed description of the invention] The purpose of this invention is to improve the insulation of the secondary coil in the case of a closed magnetic circuit type ignition coil, and at the same time to reliably prevent the coil and iron core from moving within the case. .

A conventional closed magnetic circuit type ignition coil has a primary coil 1 passed through a bobbin of a secondary coil 2, as shown in Fig. 1.
Normally, the upper legs 3a of the U-shaped core 3 are inserted into the bobbin of the primary coil from the left and right, and U-shaped contact plates 4 are placed on both sides of the core, and rivets 5 are inserted through both contact plates and the four corners of the core. This tightens the iron core between the plates and assembles both coils 1 and 2 together. After placing this assembly horizontally in a case 6 with an open top, the spring 7 is placed on top of the secondary coil. The insulating cap 8 is fitted into the open part of the case, and the open edge of the case is crimped onto the flange 8a of the cap to seal it. The inside is filled with insulating oil 9, the high voltage terminal 10 is placed inside the tower section, and the high voltage terminal 10 is screwed into the hole 8b' and fixed to the bottom of the tower section with the tightened screw 11, whereby the spring 7 is fixed at the lower end of the screw. A lower voltage is applied to electrically connect the high voltage end of the secondary coil to the high voltage terminal 10, and the core and coil assembly is pressed and fixed to the bottom of the case.

As the cross-sectional view of the secondary coil is shown in Fig. 2, insulating paper 2a is interposed between each layer of wire winding, so there is a diameter of the wire between each end of the inner and outer insulating paper. A gap 2a' corresponding to the gap 2a' is generated.

Therefore, if the oil level of the insulating oil 9 filled in the case is as high as L-h, and the secondary coil is immersed in the insulating oil to the top, the wire of the secondary coil can be connected to the + terminal 12 of the primary. The winding start lead wire of the primary coil,
The insulation between the winding end lead wire of the primary coil connected to the primary - terminal 13 and the winding start lead wire of the secondary coil is maintained by insulating oil, but as the ambient temperature drops,
When the oil level drops to L-l and the upper part of the secondary coil is exposed above the oil level, the insulation of the exposed upper part cannot be maintained by the insulating oil, so the high voltage induced in the secondary coil is transferred to the primary terminal 12. , 13, and the performance of the ignition coil deteriorates. In addition, vibrations applied to the ignition coil may cause the core and coil assembly to shift laterally and vertically within the case, resulting in breakage of the lead wires connected to the respective primary terminals 12 and 13. The spring 7 may come off the lower end of the screw 11 and become non-functional, and the secondary coil may come close to the side wall of the case, resulting in poor pressure resistance.

Therefore, the present invention has a downward surrounding wall on the inner surface of the cap that surrounds the upper halves of both the primary and secondary coils that protrude above the upper surface of the core, and that presses down the upper surface of the core toward the bottom of the case at the lower end. Provided and gap 2
The above-mentioned conventional problem is solved by providing means for bending each end of the insulating paper downward to close the gap on both end walls of the surrounding wall opposite to each end of the insulating paper that maintains a′. This solved the problem.

Figures 3 to 5 show an embodiment of the present invention.
14 indicates the surrounding wall. The surrounding wall is integrally formed when the cap 8 is molded from plastic.

Also, one or more holes or slits 14' as shown are provided so that when the cap is caulked to the open edge of the case and then filled with insulating oil, the insulating oil quickly flows out of the surrounding wall and spreads into the case. Set them aside.

Of course, the downward length of the surrounding wall 14 is appropriately determined in consideration of the depth of the case 6 and the height of the iron core 3.

Then, each end of the insulating paper of the secondary coil is bent downward, and in order to close the gap between the insulating papers, each end wall 14a, 1 of the surrounding wall 14 facing each end of the insulating paper is bent.
In this embodiment, a slope 15 is provided on the inner surface of 4a, which slopes upward and inward.

When an ignition coil is assembled using this cap, as shown in FIG. Since the upper halves of both the primary and secondary coils that protrude upward are surrounded by the surroundings, the core and coil assembly will not move within the case even if subjected to vibrations, leading to breakage of the lead wires and poor voltage resistance. does not occur. Moreover, due to the slope 15 of the inner surface of each end wall of the surrounding wall, each end of the insulating paper of the secondary coil is bent downward more strongly the higher the end, thereby closing the gap. As a result, even if the level of the insulating oil filled in the case drops due to a drop in ambient temperature, as long as each end of the insulating paper bent downward is immersed in the insulating oil,
Insulating oil is sucked up and filled between the insulating paper by capillary action. Therefore, the secondary coil and each primary terminal 12,1
The insulation between the lead wires connected to 3 is maintained, eliminating the possibility of high voltage leaking to the lead wires and degrading performance.

FIG. 6 shows an embodiment in which one or more steps 16 are provided instead of providing an inclination on the inner surface of the end wall 14a of the surrounding wall 14 as in the above embodiment. Each end of the insulating paper is bent downward to close the gap, and when the oil level drops, the oil can be drawn up by capillary action and maintained between the insulating papers. At the center of the inner surface of the cap surrounded by the surrounding wall 14, a short cylindrical wall 17 with a downward length surrounding the spring 7 is provided.
By integrally forming the spring 7 in the same manner as the surrounding wall, it is possible to prevent the spring 7 from coming off from the lower end of the screw 11 and preventing the high voltage from flowing to the high voltage terminal. Further, if the lower end of this cylindrical wall 17 is used to push down the upper surface of the secondary coil, it will help prevent the core and coil assembly from moving. In this case, holes or slits 17' are also provided around the cylindrical wall so that the insulating oil can flow out.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional closed magnetic circuit type ignition coil.
Fig. 2 is an enlarged sectional view of a part of the secondary coil, Fig. 3 is a sectional view of an embodiment of the closed magnetic circuit type ignition coil according to the present invention, and Fig. 4 is a view from the back of the cap used in the above. 5 is a bottom view, and FIG. 6 is a cross-sectional view of another embodiment of the present invention. In the figure, 1 is a primary coil, 2 is a secondary coil, 2
3 is the insulating paper, 3 is the iron core, 6 is the case, 8 is the cap, 9 is the insulating oil, 14 is the surrounding wall, 14a is the end wall, 15 is the slope of the inner surface of the end wall, and 16 is the step.

Claims (1)

[Scope of claim for utility model registration] Closed magnetic circuit type in which the assembly of both the primary and secondary coils and the iron core is housed in a case, a cap is fitted into the open part of the case to fix it, and the case is filled with insulating oil. The ignition coil has a downward surrounding wall on the inner surface of the cap that surrounds the upper halves of both the primary and secondary coils that protrude above the upper surface of the core, and that presses down the upper surface of the core toward the bottom of the case at the lower end. A closed magnet, characterized in that the inner surface of each end wall of the surrounding wall facing each end of the insulating paper of the secondary coil is provided with means such as an incline, a step, etc. for bending each end of the insulating paper downward. road type ignition coil.