JPS58122713A - Mold ignition coil for internal combustion engine - Google Patents

Abstract

PURPOSE:To obtain superior heat resistance and heat shock resistance by concentrically positioning a cylindrical body made of an electrical insulating material having elasticity between the primary coil and the secondary coil. CONSTITUTION:A cylindrical body 8 made of an electrical insulating material having heat resistance and elasticity is engaged with the inside circumference of a bobbin 5 for the secondary coil 6. A coil 6 is positioned together with the cylindrical body 8 at the outside of the primary coil 1 concentrically with the letter. Next, a thermosetting resin 7 is poured to seal the primary and the secondary coils 1, 6 while fixing the cylindrical body 8. With this arrangement, it is possible to absorb and mitigate stress by the elastcity of the cylindrical body 8 even if the resin is stressed when the internal temperature of an ignition coil repeatedly increases and decreases by the running and stoppage of a car, for example. Therefore, the occurrence of cracks can be prevented by greatly distorting the coil 6 and the resin 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molded internal engine ignition coil in which a primary coil, a secondary coil, and a secondary coil are concentrically enclosed in a case using thermosetting synthetic resin cast into the case. In particular, the purpose is to improve its heat resistance and heat resistance.

In the conventional molded ignition coil, as shown in Jlt@IK, the iron core 3 is press-fitted into a bobbinco in which one turn of the primary coil 1 is mounted, and the iron core 3 is passed through it. By fitting one end of the bobbin 1 into the hole and fixing it, the primary coil I is housed inside the case, and the iron core 3 is passed through the top and bottom of the case, keeping a distance of 111Kf!l! outside the primary coil inside the case. Place the secondary coil 6 concentrically wound in a bopi/j manner, inject a thermosetting IIi resin, such as an epoxy resin, into the case up to the top (l), and then fill the case with the primary coil 11 and the secondary coil A+C resin. It is common to encapsulate this in resin while allowing it to bleed.

However, if you simply equip and use this automatically,
During continuous operation in an atmosphere, the AT of the beginning of the 40th turn of the secondary coil near the -secondary coil increases significantly due to heating from the primary coil, and immediately after stopping operation, the ignition coil reaches the ambient temperature. The thermosetting resin 7 is subjected to repeated thermal stress as the internal @ change descends until the secondary coil 6, the tree I! 11? Cracks occur in the layer 7, causing problems such as dielectric breakdown.

Therefore, in the present invention, a cylinder made of an elastic electrically insulating material is arranged concentrically between the primary coil and the secondary coil, and both the primary and secondary coils are simultaneously fixed in the case using thermosetting resin. This eliminates the above-mentioned drawbacks of the conventional technology and allows it to be used without any problems even under harsher atmospheric temperature fluctuations and pouring.

Figure 2 shows a first actual example of the ignition coil of the present invention, in which a cylinder t made of heat-resistant rubber such as Kono Rubber is fitted onto the inner shoulder of the bobbin 5 of the secondary coil, and this cylinder The next coil number is arranged concentrically outside the primary coil with an interval, and then the thermosetting tree 11? Both the secondary and secondary coils 71 are cast.
At the same time as enclosing 4, the cylindrical body l is fixed. As a result, the internal temperature of the ignition coil rises and falls repeatedly as the car is operated and stopped, and even if the resin receives stress, it is absorbed and relaxed by the elasticity of the cylinder 1.The secondary coil and resin 7 are greatly distorted. This can prevent cracks from occurring.

The second embodiment shown in Fig. 3 is similar to the first embodiment, in which a rubber cylindrical body L is fitted onto the inner periphery of the bobbin S of the secondary coil, but in ζ\ the secondary coil is wound in parts. It is wound on a bobbin. In this case, the thermal stress that the resin tube receives is absorbed and relaxed by the elasticity of the cylindrical body t, preventing the occurrence of cracks.In addition, the electrical insulation property of the cylindrical body prevents the occurrence of cracks between the primary coil and the split-wound secondary coil. The withstand voltage is improved to that of a plane.

The cylindrical body disposed between the primary coil and the secondary coil is not limited to being made of rubber such as Kripun rubber, but it may also be a cylinder that forms closed cells with vacuum, inert gas, or air as in the embodiment shown in Fig. 4. The cylindrical body t may be formed by foam molding of synthetic resin.

In this case, the compressibility of the closed cells can absorb and relieve the thermal stress of the resin, and the heat insulating properties of one cell can suppress the rise in temperature between the secondary coil and the resin.

As is clear from the above, the present invention has excellent heat resistance and heat stain resistance, and does not cause cracks in the secondary coil or cast thermosetting resin even when used under severe ambient temperature conditions. First, it is possible to provide a molded ignition coil that does not cause layered insulation, dielectric breakdown, or the like.

The length of the cylindrical body in the axial direction may be as long as it reaches from the bottom of the case to the top as shown in Figure 2.3, but the length K should be long enough to shield the second coil, and it should be raised from the bottom with a single fat pipe. It may be fixed inside the case.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional molded ignition coil, the first intention is a sectional view of a molded ignition coil according to the third practical example of the present invention,
FIG. 3 is a sectional view of the molded ignition coil of the second embodiment, and FIG. 4 is a sectional view of another embodiment.
is the primary coil; J is the iron core;

Claims (1)

[Scope of claims] In a molded ignition coil for an internal combustion engine in which both coils are enclosed in a thermosetting 5 liter, a cylinder made of heat-resistant and elastic electrically insulating material is placed between the primary coil and the secondary coil in the case before injecting the thermosetting resin. A molded ignition coil for an internal combustion engine in which the bodies are arranged concentrically and fixed with an injected thermosetting resin to ensure 411 details. (2) In the ignition coil according to claim (1), the cylinder body is made of silicone. A molded ignition coil for an internal combustion engine that is molded from rubber or other rubber material. (3) In the ignition coil according to claim (1), the cylinder body is molded from a foam having closed cells. Molded ignition coil.