JP2002299135A - Ignition coil for internal-combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil, for an internal-combustion engine, which is of high reliability in its assembly in the ignition coil which is mounted on the plug hole of the engine, which directly supplies high voltage to ignition plug. SOLUTION: Regarding heat generated when the bonding part of a primary copper wire situated in the upper housing part of a case used to house an ignitor to a sheetlike terminal is welded, the transmission of the heat to a terminal base can be reduced by a cutout which narrows the terminal width. A maximum-stress generation part is hardly subjected to a thermal strain, the part is made to be easy to be bent by a V-shaped nib, a tensile load can be reduced, the maximum stress generation part is hardly subjected to a deformation strain, and the ignition coil whose reliability is enhanced and whose service life is long can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for an internal combustion engine for supplying a high voltage to an ignition plug, and more particularly to an ignition coil having a built-in igniter for controlling a primary current.

[Prior art]

An example of the structure of an ignition coil mounted in a plug hole of an engine and directly supplying a high voltage to an unillustrated ignition plug to which the prior art is applied will be described with reference to FIGS. 1 and 2. FIG. The ignition coil for directly supplying a high voltage to the ignition plug includes a primary voltage input unit 12 in an upper storage portion 11b of a case 11 and an igniter 1 for turning on and off a primary current.
3 is stored. A plate-like terminal 41 is provided between the voltage input section 12 and the primary coil 15 and between the igniter 13 and the primary coil 15.
And the plate-shaped terminal 41 is connected to the terminal block 4.
2 and the primary coil 15 and the plate terminal 4
1 is welded. Case 1
At the center of 1, a center iron core 18 having magnets 21-21 for generating a magnetic flux in the opposite direction to the magnetic flux generated by the primary coil 15 in order to suppress saturation of the magnetic flux of the iron core is stored at both ends, Coaxially with the center iron core 18, two
Secondary coil 17 wound with a secondary copper wire and primary bobbin 14
A primary coil 15 wound with a primary copper wire and an armor core 19 formed in a cylindrical shape and having a cutout in a part of its circumference are arranged in order, and a secondary high-voltage terminal is provided on the bottom of the case 11. 2
The secondary high-voltage terminal 22 is electrically connected to the secondary coil 17 and a spring 23 in the high-voltage tower 11a provided in the case 11, and is filled with epoxy resin through an opening in the upper part of the case 11. Then, the ignition coil is placed in a curing furnace maintained at a uniform curing atmosphere temperature, and the epoxy resin is cured for a certain period of time to insulate and seal. Further, the high-voltage tower 11a is provided with a protector 25 so that a high voltage does not leak to a metal part such as a plug hole (not shown).

During operation of the ignition coil, a primary current is input from the primary voltage input section 12 by switching of the igniter 13, the primary coil 15 is energized, and the primary coil 15 generates magnetic energy. The generated magnetic energy propagates through the center iron core 18 and the outer core 19 and is held.
When the primary current is interrupted by the switching of the igniter 13 at the timing of ignition, the energy of the magnetic field held previously becomes high voltage due to the electromagnetic induction of the primary coil 15 and the secondary coil 17 via the iron core. And is generated in the secondary coil 17. The generated high voltage is applied to the secondary coil 17.
Through the secondary high voltage terminal 22 and through the spring 23 to an unillustrated spark plug.

[0004]

The temperature of an ignition coil for an internal combustion engine as described above rises to about 130 ° C. during operation of the engine due to self-heating or heat of the engine. It is. Since each member is bonded to each other by a hard epoxy resin, when each member having a different linear expansion coefficient expands and contracts with a change in temperature,
Each member receives a strong stress from each other. In particular, in the above-described upper housing portion 11b of the ignition coil, since the amount of epoxy resin per unit volume is large, expansion and contraction are significantly increased due to repeated thermal stress, and cracks are generated.

[0005] In particular, welding heat generated at the time of welding by welding the joint portion 43 between the primary coil 15 and the plate-shaped terminal 41 reaches the terminal block 42 holding the terminal via the plate-shaped terminal 41 and expands. The portion where the maximum stress is generated due to shrinkage is subjected to thermal strain, and cracks are induced on the joint surface between the plate-shaped terminal 41 and the terminal block 42. Further, the tensile force generated by the upper electrode and the lower electrode during welding reaches the terminal block 42 that holds the plate-shaped terminal 41 via the plate-shaped terminal 41, and receives a deformation strain at a maximum stress generating portion and the plate-shaped terminal 41 is deformed. Cracks are induced on the joint surface of the terminal block 42. The present invention has been made in view of the above problems, and in an ignition coil for directly supplying a high voltage to an ignition plug, the ignition coil is mounted on a plug hole of an engine,
It is an object of the present invention to provide a highly reliable ignition coil for an internal combustion engine.

[0006]

According to a first aspect of the present invention, there is provided an iron core, a primary coil, a secondary coil disposed coaxially with the iron core, and the primary coil. And an igniter for switching the current flowing in the case. An ignition coil for supplying a high voltage directly to an ignition plug housed in a case. The plate-like terminal for welding and fixing the end of the primary coil holds the plate-like terminal. It is characterized in that a sharpening is provided to reduce the terminal width of a part exposed from the terminal block.

According to a second aspect of the present invention, an iron core, a primary coil and a secondary coil arranged coaxially with the iron core, and an igniter for switching a current flowing through the primary coil are provided.
In an ignition coil for supplying a high voltage directly to an ignition plug housed in a case, a V-shape is provided on a plate-like terminal for welding and fixing an end of a primary coil, and on a part of a terminal exposed from a terminal block holding the plate-like terminal. Is provided.

[0008]

According to the above feature, the heat generated when welding the joint between the primary copper wire and the plate terminal can be reduced by reducing the width of the terminal to reduce the heat transfer to the terminal block. Therefore, the joint surface between the plate-shaped terminal and the terminal block at the position where the maximum stress occurs is less susceptible to thermal distortion, and the reliability can be improved. Also, V
Due to the character-shaped dowels, this portion is easily bent, the tensile load can be reduced, and the joint surface between the plate-shaped terminal and the terminal block at the position where the maximum stress occurs is less susceptible to deformation distortion, thereby improving reliability.

[0009]

FIG. 1 is a longitudinal sectional view to which the technology of the present invention is applied.
FIG. 2 shows a top view.

1 and 2, the ignition coil for directly supplying a high voltage to the ignition plug includes a primary voltage input section 12 and an igniter 13 for turning on and off the primary current in an upper storage section 11b of a case 11. To store. Voltage input sections 12 and 1
1 between the primary coil 15 and between the igniter 13 and the primary coil
Numeral 5 is connected via a plate-shaped terminal 41 to allow the current input from the voltage input unit 12 to flow to the primary coil 15 and to supply the current output from the primary coil 15 to the igniter 1.
It has the function of flowing to 3. At the center of the case 11, a center iron core 18 having magnets 21-21 for generating a magnetic flux in the opposite direction to the magnetic flux generated by the primary coil 15 in order to suppress the saturation of the magnetic flux of the iron core is housed at both ends. A secondary coil 17 in which a secondary copper wire is wound around a secondary bobbin 16 and a primary coil 15 in which a primary copper wire is wound around a primary bobbin 14 coaxially with the center iron core 18. An exterior iron core 19 formed in a cylindrical shape and having a notch in a part of its circumference is arranged in order, and a secondary high voltage terminal 22 is provided at the bottom of the case 11, and the secondary high voltage terminal 22 is a secondary coil. 17 is electrically connected to a spring 23 in a high-pressure tower 11a provided in the case 11, and is filled with an epoxy resin through an opening in the upper part of the case 11 to form a curing furnace maintained at a uniform curing atmosphere temperature. Put the ignition coil and take a certain time Curing the epoxy resin, which seals the insulating seal. Further, the high-voltage tower 11a is provided with a protector 25 so that a high voltage does not leak to a metal part such as a plug hole (not shown).

The plate-like terminal 41 is held by a terminal block 42, and a joint 43 between the primary coil 15 and the plate-like terminal 41 is welded. Primary coil 1 by welding
5 and the plate-like terminal 41 are electrically and mechanically connected.
In the welding of the joint 43 between the primary coil 15 and the plate-like terminal 41, heat is applied in proportion to the resistance value of the sandwiched portion by applying a current by sandwiching the joint between the two positive electrodes and the minus electrode. Then, the heat causes the metal in the portion sandwiched between the electrodes to melt and join.

A first embodiment will be described with reference to FIG. In order to reduce the heat generated when the joint between the primary coil 15 and the plate-shaped terminal 41 is welded reaches the terminal block 42, a sharp edge 44 is attached to the plate-shaped terminal between the joint and the terminal block 42. Provide. The shape of the sharpening 44 is circular in order to prevent stress concentration, and the sharpening amount is such that the strength of the plate-shaped terminal 41 does not decrease. Therefore, when the sheet width is set to 5 times the sheet pressure from the end face in the terminal width direction. Is within 1/2 to 2 times the plate pressure. With the above configuration, it is possible to reduce the heat generated during welding from reaching the terminal block 42 via the plate-shaped terminal 41. Therefore, by reducing the width of the terminal, heat transfer to the terminal block can be reduced, and the joint surface between the plate-shaped terminal and the terminal block at the position where the maximum stress occurs is less susceptible to thermal distortion, thereby improving reliability.

A second embodiment will be described with reference to FIGS. FIG. 4 is a top view of the joint, and FIG. 5 is a side view as viewed from the direction A in FIG. In order to reduce the stress that occurs in the machine after the welding of the joint and the separation of the electrode and the plate terminal from the others, the V-shaped dowel is attached to the plate terminal between the joint and the terminal block. 45 are provided. Therefore, this portion is easily bent by the V-shaped dowel, the tensile load can be reduced, and the joint surface between the plate-shaped terminal and the terminal block at the position where the maximum stress occurs is less likely to be deformed and the reliability can be improved.

[0014]

By applying the technology of the present invention to the ignition coil as described above, the heat generated when welding the joint between the primary copper wire and the plate-shaped terminal is reduced in the terminal width. By cutting, heat transfer to the terminal block can be reduced, making it less likely to receive heat distortion at the site where the maximum stress is generated. In addition, the V-shaped dowel can bend easily, reducing the tensile load and reducing the maximum stress. Since the deformation portion of the generation portion is less susceptible to deformation distortion, it is possible to provide an ignition coil having improved reliability and a long life.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention and a conventional ignition coil.

FIG. 2 shows a top view of an embodiment of the present invention and a conventional ignition coil.

FIG. 3 is a sectional view of the ignition coil according to the first embodiment of the present invention.

FIG. 4 is a sectional view of an ignition coil according to a second embodiment of the present invention.

5 shows a side view of the ignition coil shown in FIG. 4 as viewed from the direction A.

[Explanation of symbols]

 In the drawings, the same reference numerals indicate the same or corresponding parts. DESCRIPTION OF SYMBOLS 11 Case 11a High voltage tower part 11b Upper storage part 12 Primary voltage input part 13 Igniter 14 Primary bobbin 15 Primary coil 16 Secondary bobbin 17 Secondary coil 18 Central iron core 19 Exterior iron core 21 Permanent magnet 22 Secondary high voltage terminal Reference Signs List 23 spring 25 protector 41 plate-shaped terminal 42 terminal block 43 joint part 44 sharpening 45 V-shaped dowel

Claims (2)

[Claims] 1. An ignition plug containing an iron core, a primary coil and a secondary coil arranged coaxially with the iron core, and an igniter for switching a current flowing through the primary coil in a case. In the ignition coil supplying the voltage, 1
An ignition coil for an internal combustion engine, characterized in that a plate-shaped terminal for welding and fixing an end of a next coil is provided with a squeeze to narrow a part of a terminal exposed from a terminal block holding the terminal. 2. An ignition plug containing an iron core, a primary coil and a secondary coil arranged coaxially with the iron core, and an igniter for switching a current flowing through the primary coil in a case. In the ignition coil supplying the voltage, 1
An ignition coil for an internal combustion engine, wherein a V-shaped dowel is provided on a part of a terminal exposed from a terminal block holding the plate-shaped terminal on a plate-shaped terminal for welding and fixing an end of a next coil.