JP3385313B2 - Molded ignition coil for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine mounted on an internal combustion engine, for example, an automobile engine, for supplying a high voltage for generating spark discharge to a spark plug of the engine. The present invention relates to a molded ignition coil for an engine. [0002] The present applicant has filed a Japanese Patent Application No. 11-1928.
No. 19 and Japanese Utility Model Application No. 11-5061, an endless outer ring core and a closed magnetic path are formed with the outer ring core across the interior surrounded by the outer ring core, and the primary, concentrically fitted primary,
An iron core-coil assembly consisting of a linear center iron core penetrating and supporting both secondary coils and a high voltage terminal connected to a spark plug were held at the bottom, and the iron core-coil assembly was housed horizontally inside. A bottomed insulating case having a main housing portion, an auxiliary housing portion which is separated from the main housing portion by an insulating wall and houses a power switch therein, an annular portion contacting the upper surface of an outer ring core, and the annular portion Drooping from the inner circumference of
The core-coil assembly is provided with opposing arc-shaped hanging walls integrally in contact with the opposing inner peripheral surfaces of the outer ring core across the respective ends of the center core of the core assembly, and mounted over the outer ring core. A resin core cover is cast inside the main housing and the auxiliary housing of the insulating case, the core-coil assembly and the iron cover are inside the main housing, and the power switch is inside the auxiliary housing. A molded ignition coil for an internal combustion engine, which is provided with a solidified layer of an insulating resin to be embedded and fixed, respectively, has been proposed. [0003] The portion of the iron core facing the low-height insulating wall separating the main housing portion and the auxiliary housing portion has a clearance in consideration of assemblability in manufacturing. When a thermosetting insulating resin is cast, the resin enters the clearance and solidifies as a thin layer. The iron core housed in the main housing part has poor adhesion to the thermosetting resin such as epoxy, and when a thermal shock test is performed, the difference in the coefficient of thermal expansion between the iron core and the thermosetting resin causes Cracks occur, especially in the above-mentioned clearance portion, because the resin layer is a thin layer, the crack progresses to the upper surface of the solidified layer of the insulating resin on the upper part of the insulating case,
Insulation failure results in coil disconnection and poor performance.
To prevent this, it is necessary to increase the clearance and increase the thickness of the insulating layer. However, this increases the size of the insulating case, so that the ignition coil becomes large and the amount of the thermosetting insulating resin used increases. SUMMARY OF THE INVENTION The present invention has been developed to solve the above-mentioned problems. In an ignition coil of the type described in the prior art, an annular portion 31 of an iron core cover 30 is provided. The outer periphery of the insulating case is brought into contact with the inner periphery of the insulating case, and a portion facing the insulating wall 24 is provided with an overhang portion 33 which covers the insulating wall 24 from above and is supported by the wall 24. In the illustrated embodiment, reference numeral 10 denotes an iron core-coil assembly, which is an annular outer ring iron core 13, a center iron core 14 crossing the inside of the outer ring iron core, and an outer periphery of the center iron core. And a secondary coil 12 fitted and supported outside of the primary coil. The outer ring core comprises a C-shaped core 13a and open ends of the C-shaped core. Although it is composed of the I-shaped iron core 13b to be connected, it may be composed of two opposing U-shaped iron cores having a semicircular shape. Further, the iron core composed of the outer ring core and the center core is an E-shaped core having the center arm as the center arm among the three arms, and an I-shaped core which connects the three arms of the E-shaped core at right angles. In any case, an annular outer ring core and a primary, secondary, outer and inner concentrically fitted outer and inner cores are fitted concentrically.
What is necessary is just to have the center iron core which penetrates and supports both the following coils. [0006] Between a part of the inner circumference of the outer ring core 13 and one end of the center core 14 facing a part of the inner circumference, a closed magnetic circuit formed by the outer ring core and the center core is connected in series. A magnetic bias is applied by disposing a permanent magnet piece 15 to the ignition coil. During use as a product, when the current flowing through the primary coil is interrupted, the amount of change in the magnetic flux of the iron core is increased, and the magnetic flux is induced in the secondary coil. It is preferable to increase the voltage of the high voltage that causes sparks in the spark plug of the internal combustion engine to improve the output of the ignition coil. Reference numeral 20 denotes a high-voltage terminal 22 for receiving the core-coil assembly horizontally and connecting it to a spark plug at the bottom.
The main housing 21 holding the power switch 17 is separated from the main housing by an insulating wall 24 having a low height.
An insulating case formed of a synthetic resin having a bottom and an open upper surface 20 'having an auxiliary storage portion 23 for storing the storage case. In order to fix the outer ring core 13 to the middle stage of the inner circumference of the main housing,
The main accommodating portion is a flat annular insole 27 along the lower surface of the outer ring core, and is recessed downward from the inner periphery of the annular insole, and the lower halves of the primary and secondary coils supported by the center core therein. The high-voltage terminal 22 is held in a high-pressure cylindrical portion 22 ′ having a recess 28 for housing the portion, and protruding downward from the center of the recess 28. When molding an insulating case, a primary terminal is attached to the side wall of the auxiliary accommodating portion 23 by insert molding in a penetrating manner, and a primary terminal socket 26 surrounding the primary terminal is provided outside the side wall at the same time. Numeral 30 is the same shape as the outer ring core of the core-coil assembly, and has a thick annular portion 31 overlapping the upper surface thereof, and hanging down from the inner periphery of the annular portion, straddling each end of the center iron core 14. An iron core cover formed of a synthetic resin integrally having opposed arc-shaped hanging walls 32, 32 in contact with the opposed inner peripheral surfaces of the outer ring core. The core cover 30 is placed on the outer ring core 13 of the core-coil assembly. At this time, the arc-shaped hanging walls 32, which oppose from the inner periphery of the annular portion of the iron core cover,
32 contacts the inner periphery of the outer ring core. The power switch 17 is accommodated in the auxiliary accommodating portion 23, and the core-coil assembly in which the core cover 30 is covered on the outer ring core is accommodated in the main accommodating portion, and the outer ring core is attached to the annular midsole 27. And a winding end of the primary coil, a winding end of the primary coil, and a winding end of the secondary coil.
Connect to the next terminal, and connect the end on the winding end side of the secondary coil to the high voltage terminal. When the core-coil assembly 10 with the core cover mounted thereon is accommodated in the main accommodating portion, most of the outer periphery of the thick annular portion 31 of the core cover comes into contact with the inner periphery of the insulating case, and the insulating wall 24 is provided. Overhang 33 provided at the part facing
Are supported by the insulating wall 24 covering the insulating wall 24 from above. That is, the projecting portion 33 of the annular portion of the iron core cover is
4 contacts the upper surface. A flowable thermosetting insulating resin, for example, an epoxy resin, is poured into the main housing, and the resin in the flowed state passes between the inner periphery of the outer ring core and the center core to form the main housing. When the inside is filled from below and the liquid level of the resin is higher than the iron core cover, the resin overflows to the auxiliary accommodating portion. Thus, the core-coil assembly 10 and the core cover in the main housing portion of the insulating case are filled with the insulating resin so that the power level of the power switch 1 in the auxiliary housing portion is reduced.
When the insulating resin 7 is filled with the insulating resin, the liquid level of the insulating resin is reduced by the insulating resin continuously injected thereafter.
Rise inside the insulating case 20 including the
Reach near the open top of the. At this stage, the casting of the insulating resin is stopped, the insulating resin is solidified, the core-coil assembly and the iron core cover are fixed inside the main housing part by the solidified layer 29, and the power switch is fixed inside the auxiliary housing part. I do. At this time, the insulating wall 24 inside the main housing portion
Then, a thin layer 29 'in which the insulating resin is solidified is generated in a clearance between the iron core facing the wall and the iron core. However, since the overhang portion 33 of the core cover covers the thin layer 29 'from above, even if a crack occurs in the thin layer from the end face of the iron core portion, the crack is blocked by the overhang portion 33 of the iron cover. Therefore, it does not proceed to the upper surface of the solidified layer of the insulating resin. Even if there is a gap between the outer periphery of the outer ring core 13 and the inner wall of the main accommodating portion 21 of the insulating case, and a thin layer 29 ″ of a solidified layer of the insulating resin is generated there, the annular shape of the core cover is not affected. Since the outer periphery of the portion 31 is in contact with the inner wall of the main accommodating portion of the insulating case, even if a crack occurs in the thin layer from the end face of the iron core, it is blocked by the outer circumference of the annular portion of the iron core cover.
Therefore, also in this case, the crack does not progress to the upper surface of the solidified layer of the insulating resin. As apparent from the above, according to the present invention, even if a crack occurs in the thin layer of the solidified insulating resin layer from the end face of the iron core, the crack is blocked by the iron core cover and solidified. Do not advance to the top of the layer. Therefore, an ignition coil that does not cause insulation failure can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a plan view of an ignition coil according to the present invention before casting an insulating resin, and FIG. Sectional view. FIG. 2 is an exploded perspective view of an outer ring iron core, an iron core cover, a center iron core and a primary coil assembly according to the first embodiment; FIG. 3 is an explanatory view showing a state where the outer ring iron core is covered with an iron core cover and is housed in a main housing part of an insulating case. DESCRIPTION OF SYMBOLS 10 Iron core-coil assembly 11 Primary coil 12 of iron core-coil assembly 12 Secondary coil 13 Outer ring iron core 14 Center iron core 15 Permanent magnet piece 17 Power switch 20 Insulating case 21 Insulating case main housing part 22 High-voltage terminal 22 ′ High-pressure cylinder 23 Auxiliary housing 24 Insulating wall 26 Primary terminal socket 27 Annular middle bottom 28 of main housing 29 Depression of main housing 29 Solidified layer of insulating resin 29 ′ Thin layer of insulating resin 29 ″ Insulating resin Thin layer 30 of iron core cover 31 Annular portion of iron core cover 32 Arc-shaped hanging wall 33 of iron core cover Overhang of insulating cover

Continuation of the front page (72) Inventor Toshiyuki Kawatani 2-1-26-1 Tsutodori, Nada-ku, Kobe-shi, Hyogo Inside Hanshin Electric Co., Ltd. (56) References JP-A 2001-23839 (JP, A) 145230 (JP, U) Japanese Utility Model 57-124120 (JP, U) Registered utility model 3065554 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 38/12

Claims (1)

(57) [Claim 1] An endless outer ring core 13 and a closed magnetic path are formed with the outer ring core so as to cross the inside surrounded by the outer ring core and are fitted concentrically. Next, the core-coil assembly 10 comprising a linear center iron core 14 penetrating and supporting both the secondary coils 11, 12 and the high-voltage terminal 22 connected to the ignition plug are held at the bottom, and the core-coil assembly is provided. A bottomed insulating case 20 having a main housing portion 21 in which the three-dimensional body 10 is horizontally housed, and an auxiliary housing portion 23 separated from the main housing portion by an insulating wall 24 and housing the power switch 17 therein; An annular portion 31 that comes into contact with the upper surface of the annular core 13, and a portion that hangs down from the inner periphery of the annular portion and straddles each end of the center core 14 of the core-coil assembly and contacts the opposed inner peripheral surface of the outer annular core. Opposing arc-shaped hanging walls 32, 3 And a resin core cover 30 mounted on the outer ring core and mounted on the outer ring core. The core-coil assembly 10 is cast into the main housing portion and the auxiliary housing portion of the core case. The power switch 17 and the iron core cover 30
And a solidified layer 29 of an insulating resin for embedding and fixing in the interior of the auxiliary accommodating portion 23, respectively, the outer periphery of the annular portion 31 of the iron core cover 30 to the inner periphery of the insulating case. A mold-type ignition coil for an internal combustion engine, wherein a protrusion 33 is provided at a portion facing the insulating wall 24 so as to cover the insulating wall 24 from above and to be supported by the wall 24.