JPH0215306Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to an ignition coil for an internal combustion engine.

[Conventional technology]

Conventional ignition coils are generally made by injecting and hardening casting resin into a case that houses the primary and secondary coils placed around the outer periphery of the core. Because the coefficients of linear expansion of the two materials differed greatly, there was a drawback that cracks occurred in the casting resin during the thermal shock test.

Conventionally, in order to eliminate the above-mentioned drawbacks, it has been considered to cover the outer periphery of the core with a primary bobbin to prevent direct contact between the core and the casting resin (for example, Utility Model No. 58-87317 However, since it is unavoidable that the core moves relative to the primary bobbin etc. due to the cooling/heating cycle, this relative movement of the core causes damage to the primary bobbin etc. that covers the core. There is a drawback.

[Problem that the invention seeks to solve]

Therefore, the present invention reliably prevents the occurrence of cracks in the casting resin and damage to the primary bobbin, etc. due to cooling and heating cycles.

[Means for solving problems]

Therefore, in the present invention, the core and the primary and secondary coils arranged around the core are housed in a case.
This ignition coil for an internal combustion engine is formed by injecting and hardening a casting resin into the case, and includes a primary bobbin in which the core is inserted and the primary coil is wound around the outer periphery of the primary bobbin. A lid is provided on the end surface to protrude from the casting resin, a through hole smaller than the outer diameter of the core is formed in the lid, and a gap is formed between the lid and the end surface of the core. An ignition coil for an internal combustion engine is provided.

[Effect]

This allows the core to move within the primary bobbin by the amount of the gap, thereby absorbing the difference in linear expansion coefficients.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings. In Fig. 1, 1 is a cylindrical 1 made of synthetic resin.
A lid portion 1a is integrally provided at the tip of the next bobbin, and a small through hole 10 is provided in this lid portion 1a.
is formed. Further, a large diameter portion (stopper portion) 1b is formed on the primary bobbin 1 adjacent to the lid portion 1a, and a winding wire is formed on the outer periphery of the intermediate portion of the primary bobbin 1 adjacent to the large diameter portion 1b. A primary coil 2 is formed in the winding recess 1c.
is wound. Further, the other end of the primary bobbin 1 is an open end. 3 is a secondary bobbin made of synthetic resin with a plurality of winding grooves formed on the outer periphery, and primary bobbin 1
The secondary coil 4 is arranged on the outer periphery of the secondary coil 4, and the secondary coil 4 is wound in parts in the winding groove on the outer periphery. Further, a lid portion 3a is formed at one end of the secondary bobbin 3, and a core positioning protrusion 3b that projects in the axial direction toward the inside of the primary bobbin 1 is integrated into the center of the inner bottom surface of the lid portion 3a. Further, a terminal fixing projection 3c is integrally formed on the outside of the lid portion 3a.
Reference numeral 5 designates a secondary terminal fixed to a terminal fixing protrusion, which includes a protrusion 5a to which the high-voltage end of the secondary coil 4 is connected, and a threaded portion 5b to which the high-voltage cord is connected.
It has Reference numeral 6 denotes a synthetic resin case, in which a partition wall 6a is integrally formed to partition the ignition coil side and the control circuit side, and a mounting stay 6b is integrally formed on the outer wall. Furthermore, a connector part 6c for the primary terminal and a cylindrical part 6d for the high voltage cord are integrally formed on the bottom wall so as to communicate with the inside of the case 6, and the screw part 5b of the secondary terminal 5 is connected to the cylindrical part 6d for the high voltage cord. It is placed protruding inside. 7 is a thermosetting resin that is vacuumed and injected into the case 6 and then hardened;
The lid portion 1a is made to protrude from inside the resin 7 to the outside. 8 has approximately the same diameter as the inner diameter of the primary bobbin 1 (slightly smaller diameter is better), and is approximately 1 mm or more larger than the dimension from the inner surface of the lid of the primary bobbin 1 to the tip of the core positioning protrusion 3b of the secondary bobbin 3. A short cylindrical core inserted inside the primary bobbin 1, and a gap 11 of 1 mm or more is formed between the end surface of the core 8 and the lid 1a of the primary bobbin 1. has been done. Further, the core positioning protrusion 3b of the secondary bobbin 3 comes into contact with the end surface of the core 8, and the cores 8 and 1
The secondary bobbin 1 is positioned shifted in the axial direction with respect to the secondary bobbin 3, and the distance between the high voltage side (secondary terminal side) of the secondary coil 4 and the core 8 and the primary coil 2 is They are spaced apart to ensure sufficient pressure resistance even when downsized.

Reference numeral 9 denotes a control circuit section for intermittent current flowing through the primary coil 2 of the ignition coil, and is housed in the case 6 separated from the ignition coil side via a partition wall 6a.
13 is a printed circuit board on which each electric circuit component of the control circuit section 9 is mounted; 14 is a primary terminal fixed to the printed circuit board 13 and disposed within the primary terminal connector section 6c. As shown in FIGS. 3 and 4, a protruding leg portion 14a is formed on the root side end of the terminal 14, and a bent portion 14b is formed on this leg portion 14a. Embossed portion 14b and leg portion 14a
Depending on the primary terminal 14, the printed circuit board 1
It is press-fitted and fixed into the through hole 13a of No. 3.

Reference numeral 15 denotes a bush made of an elastic pair of rubber or the like attached to the outer periphery of the base side of the terminal 14, and a ring-shaped fold 15a is integrally formed on the outer periphery of the bush. The bush 15 is press-fitted into a circular hole 6e formed at the base of the primary terminal connector portion 6c so as to communicate with the inside of the case 6.
The presence of this bush 15 prevents the casting resin 7 from leaking from the bottom of the case 6.

In the above configuration, the core 8 is inserted from the open end of the primary bobbin 1, and the open end of the primary bobbin 1 is inserted inside the secondary bobbin 3. There is a gap 11 of 1 mm or more between the core 8 and the lid 1a of the primary bobbin 1, and the lid 1a of the primary bobbin 1 protrudes from the surface of the casting resin 7. Inside, there is a gap of 11 minutes that allows for free movement in the axial direction, absorbing stress caused by heating and cooling cycles,
Cold and heat resistance can be improved.

Further, the through hole 10 formed in the lid portion 1a of the primary bobbin 1 is evacuated and the casting resin 7 is inserted into the case 6.
After injecting and curing, the casting resin 7 is prevented from entering into the gap 11, and the gap 11 is reliably formed between the lid part 1a and the core 8. This is to prevent movement of the core 8 relative to the primary bobbin 1 from being obstructed.

FIG. 2 shows another embodiment of the present invention, which is different from the embodiment shown in FIG. It is something. In this embodiment as well, by forming the gap 11 between the lid portion 12 and the core 8, the same effects as in the first embodiment can be obtained.

In addition, in the embodiment described above, the ignition coil and the control circuit were housed in one case 6, but
The present invention can also be applied to a case in which only the ignition coil is housed in the case 6.

[Effect of idea]

As mentioned above, in this invention, the core moves by the gap within the primary bobbin to absorb the difference in linear expansion coefficient, which prevents cracks in the casting resin due to cooling and heating cycles, and prevents the primary bobbin from cracking. This has the excellent effect of reliably preventing damage to the product.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing one embodiment of the coil of the present invention, Fig. 2 is a longitudinal sectional view showing another embodiment of the coil of the invention, and Figs. 3 and 4 are the primary terminals in the above embodiment. FIG. 2 is a partially sectional perspective view and a partially sectional front view showing the structure of the portion. 1...Primary bobbin, 1a, 12...Lid, 2...
...Primary coil, 4...Secondary coil, 6...Case, 7...Thermosetting resin forming casting resin, 8...
Core, 10... through hole, 11... gap.

Claims (1)

[Scope of utility model registration request] In an ignition coil for an internal combustion engine, a core and primary and secondary coils arranged around the outer periphery of the core are housed in a case, and a casting resin is injected and hardened into the case, and the core is inserted inside. and a primary bobbin having the primary coil wound around its outer periphery,
A lid portion is provided on the end surface of the primary bobbin so as to protrude from the casting resin, and a through hole smaller than the outer diameter of the core is formed in the lid portion. An ignition coil for internal combustion engines with a gap formed between the coils.