JPH0320892B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to structural improvement of an ignition coil for an internal combustion engine, and by improving the winding structure of the primary coil, the coil heat generation temperature is lowered and the life of the coil is increased.

In the conventional well-known battery ignition coil, a coil having a diameter of about 0.3 mm is tightly wound about 400 times in three to four layers on a core or a primary bobbin. As a result, the center of the coil generated a lot of heat when energized.

Therefore, the present invention aims to lower the temperature of the center of the primary coil and at the same time lower the temperature of the entire coil.By reducing the number of turns at the center of the primary coil and increasing the number of turns at both ends, the center of the coil is first reduced. In addition, the heat of the coil passes through the core due to thermal conduction, and either escapes from the core's actual machine mounting hole to the mounting part of the vehicle body, etc., or decreases the number of coil turns at the position close to the core's actual machine mounting hole, that is, at both ends. The purpose is to increase the amount of heat radiation and lower the overall temperature by increasing the amount.

The present invention will be described below with reference to embodiments shown in the drawings. In Figure 1, reference numeral 1 denotes a core made of laminated rectangular silicon steel plates, which has holes 2 at both ends for attachment to the vehicle body, and is tightened and fixed to a mounting part such as the vehicle body frame with bolts (not shown). . In addition to being a magnetic core, core 2 also has the function of dissipating the heat generated by the primary coil to the vehicle frame.
The temperature also increases. 4 is a primary bobbin made of resin made by insert molding the core 1, and has collars 5a, 5.
It is divided into three winding grooves by b. Reference numeral 3 denotes a primary coil wound around the bobbin 4, with 85 to 95% of the total number of turns wound around the winding grooves at both ends, and 5 to 15% wound around the central winding groove.

Figure 2 is a characteristic diagram showing the temperature of each part of the coil when the winding structure of the coil is changed.In the conventional winding structure in which all the turns are tightly wound in one winding groove, as shown by the solid line, The temperature is 205℃ at the center and 190℃ at both ends, but in the case of the split winding shown in Figure 1, the temperature drops to 180℃ at the center and 185℃ at both ends, as shown by the broken line. As a result, the peak temperature decreased by 20℃ from 205℃ to 185℃, as can be seen from the thermal life characteristic diagram of the winding wire (temperature-lifetime characteristic diagram of modified polyester wire) shown in Figure 3. ,
The lifespan is 700 hours at 205℃, while it is 3000 hours at 185℃, which is about four times longer. Further, by lowering the temperature of the primary coil 3, the temperature of the secondary coil (not shown) wound around the outer periphery of the primary coil 3 can also be lowered, thereby extending the life of the entire coil and improving its quality.

In the above embodiment, the winding groove of the primary bobbin 4 is divided into three by the flanges 5a and 5b, but the same effect can be obtained even if the flanges 5a and 5b are omitted as long as the windings do not collapse. . Also, the primary bobbin 4
Insulating means such as insulating paper can also be used instead.

As described above, in the present invention, by winding the primary coil with more windings at both ends and less windings at the center, the highest heat generating part is closer to the mounting part of the vehicle body frame, etc., and heat radiation to the mounting part is improved. This reduces the overall coil temperature, extending the life of the wire and improving its quality. Furthermore, if the wire life is of excessive quality, the heat resistance rank of the wire can be lowered by one rank to reduce costs. Moreover, there is an excellent effect that the quality of the material of the insulating means such as the primary bobbin can be improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part showing an embodiment of the coil of the present invention, FIG. 2 is a temperature characteristic diagram of the coil shown in FIG. 1, and FIG. 3 is a thermal life characteristic diagram of the winding wire. 1...Core, 2...Mounting hole, 3...Primary coil, 4...Primary bobbin.

Claims (1)

[Claims] 1. In an ignition coil for an internal combustion engine in which both ends of the core are attached and fixed to a mounting part of a vehicle body, etc., an insulating means such as a primary bobbin or insulating paper provided on the outer periphery of the core;
An ignition coil for an internal combustion engine, comprising a primary coil wound around the insulating means, wherein the winding density at the center of the primary coil is lower than the winding density at both ends.