JPH1140444A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil which can prevent the occurrence of dielectric breakdown due to the discharge between a secondary terminal fitting and a primary coil. SOLUTION: An ignition coil is constituted by winding a primary coil 3 around the coil winding drum section 101 of a primary bobbin 1 having a high- voltage cord holding section 105 at the front end of an erected wall 104 installed to one end of the drum section 101 in the axial direction, and a secondary coil 4 around a secondary bobbin 2 surrounding the primary coil 3. A secondary terminal fitting 6 attached to the holding section 105 is connected to the secondary coil 4 through a secondary terminal board 9. In addition, grooves 110 and 111 are provided on the bobbin 2 side surface of the erected wall 104 of the primary bobbin 1, so as to make longer the creepage distance of insulation between the rear end section 6a of the secondary terminal fitting 6,and the wall 104 side end section 3a of the primary coil 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ignition coil for an internal combustion engine used for an ignition device for igniting an internal combustion engine.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show a conventional ignition coil for an internal combustion engine. In these figures, reference numerals 1 and 2 denote primary and secondary bobbins, respectively, and reference numerals 3 and 4 denote primary bobbins 1 and 2, respectively. A primary coil and a secondary coil wound on the secondary bobbin 2, 5 is an iron core, 6 is a secondary terminal fitting, and 7 is a case made of an insulating resin housing a main body of the ignition coil.

The primary bobbin 1 is formed of a molded article of insulating resin, is formed in a hollow shape, and has flange portions 102 and 10 near one end 101a and the other end 101b in the axial direction, respectively.
3 and a standing wall 10 protruding from the vicinity of one end 101a of the coil winding body 101 in the axial direction to the outside in the radial direction of the coil winding body.
4 and a bottom wall portion 105a provided so as to protrude from the tip of the upright wall to the opposite side of the coil winding body 101 and having a rear end located on the upright wall 104 side forming a part of the upright wall 104.
, And has a cylindrical high-voltage cord holding portion 105 integrally formed with an open end portion 105b. A primary coil 3 is wound around the outer periphery of the coil winding body 101, and a terminal on the winding start side and a terminal on the winding end side (both not shown) of the primary coil are respectively wound around the coil. Body 1
01 is pulled out from one end 101a side and the other end 101b side. The iron core 5 is attached in a state where a hole formed inside the coil winding body 101 is penetrated.

[0004] With the secondary terminal fitting 6 penetrating the bottom wall portion 105a closing the rear end of the high-voltage cord holding portion 105 of the primary bobbin 1 and having the tip directed toward the tip end of the high-voltage cord holding portion 105, Installed. The illustrated secondary terminal fitting 6 is formed of a tapping screw, and is screwed and attached to a bottom wall portion 105 a that closes a rear end of the high-voltage cord holding portion 105.

In the example shown in the figure, a flange plate projecting from the one end of the primary bobbin 1 on the opposite side to the upright wall 104 is formed, and the primary terminal fitting 8 is attached to the flange plate, The terminal fitting 8 includes a body 1 for winding a coil of a primary bobbin.
01 is connected to a terminal on the winding start side of the primary coil 3 which is led out from one end of the primary coil.

The secondary bobbin 2 has a plurality of flanges 202, 202,... Arranged in the axial direction on the outer periphery of the cylindrical portion 201, and the secondary bobbin 2 is formed in a coil winding groove formed between these flanges. It is a well-known device in which a coil is wound separately. In the illustrated example, several (three in the illustrated example) flange portions 20 formed on one axial end (low-pressure end) of the secondary bobbin.
The outer diameter of No. 2 is set smaller than the outer diameter of the other flange portion 202. Each of the unit coils 401, 4 is inserted into a series of coil winding grooves formed between the flange portions 202, 202,.
Are wound, and these unit coils are sequentially connected in series to form the secondary coil 4.

A flange 202 'formed at the other end (high-pressure side end) of the secondary bobbin 2 is formed thicker than the other flanges. A secondary terminal plate 9 bent into a V shape is press-fitted into the formed groove, and the terminal portion on the winding end side (high voltage side) of the secondary coil 4 is soldered to the secondary terminal plate 9. Connected by

The secondary bobbin 2 is disposed so as to concentrically surround the coil winding body 101 of the primary bobbin 1 from the outside, and is fitted to the outer periphery of the flange portions 102 and 103 of the primary bobbin. The terminal plate 9 is brought into contact with the rear end portion (the head of the tapping screw) 6 a of the secondary terminal fitting 6. Although not shown, the terminal on the winding end side of the primary coil 3 is led out from the other end 101b side of the coil winding body of the primary bobbin, and the terminal on the winding end side of the primary coil is a secondary bobbin. 2 is connected to a terminal portion on the winding start side (low voltage side) of the secondary coil 4 which is led out from one end side.

The case 7 includes the primary coil 3 of the primary bobbin 1.
Is wound so as to accommodate the coil winding body 101, the upright wall 104, and at least a part of the high-voltage cord holding portion 105 together with the secondary bobbin 2 around which the secondary coil 4 is wound. A thermosetting insulating resin such as an epoxy resin is cast in the case 7, and a main part of the ignition coil is embedded in a resin mold portion 10 formed of the cast resin.

[0010]

In the ignition coil shown in FIG. 5, the potential of the secondary terminal fitting 6 is the highest, and the upright wall 1 of the primary coil 3 is located relatively close to the secondary terminal fitting 6.
Since the end 3a on the 04 side (usually the end on which the terminal on the winding start side of the primary coil is disposed) is at a low potential, the rear end of the secondary terminal fitting 6 (the head of the tapping screw) And the end 3 a of the primary coil 3, the upright wall 104 of the primary bobbin
In some cases, discharge occurs along the interface between the resin and the resin mold portion 10 to cause dielectric breakdown.

It is an object of the present invention to provide an ignition coil for an internal combustion engine which can prevent discharge from occurring between a secondary terminal fitting and a primary coil.

[0012]

According to the present invention, there is provided an ignition coil for an internal combustion engine to which the present invention is applied. The coil winding body has a cylindrical shape, and one end in the axial direction of the coil winding body. And an upright wall protruding radially outward from the coil winding body portion, and being provided so as to protrude from a tip end of the upright wall to the opposite side to the coil winding body portion and located on the upright wall side. A primary bobbin made of an insulating resin integrally having a cylindrical high-voltage cord holding portion whose rear end portion is closed by a bottom wall portion forming a part of the upright wall, and a rear end of the high-pressure cord holding portion of the primary bobbin A secondary terminal fitting that penetrates the bottom wall that closes the part and is attached with its tip facing the tip side of the high-voltage cord holding part,
A primary coil wound around the coil winding body of the primary bobbin, a secondary bobbin provided to surround the coil winding body of the primary bobbin from the outside, and a secondary bobbin wound around the secondary bobbin. One end is connected to one end of the primary coil, the other end is electrically connected to the rear end of the secondary terminal fitting, and the coil winding body of the primary bobbin around which the primary coil is wound. A case accommodating an upright wall and at least a part of the high-voltage cord holding section together with a secondary bobbin wound with a secondary coil is provided, and an insulating resin is cast in the case.

According to the present invention, the creeping insulation distance between the rear end of the high-voltage cord holding portion and the end of the primary coil on the standing wall is increased on the surface of the standing wall of the primary bobbin on the side of the secondary bobbin. Groove was formed.

With the above construction, the creeping insulation distance between the rear end of the secondary terminal fitting and the end of the primary coil on the upright wall side can be made longer than before, so that the upright wall of the primary bobbin is provided. It is possible to prevent the occurrence of electric discharge between the secondary terminal fitting and the primary coil along the interface between the resin and the resin, thereby causing dielectric breakdown.

The grooves for increasing the creepage distance include a plurality of first grooves arranged in the radial direction of the coil winding body.
And a second annular groove surrounding the rear end of the secondary terminal fitting. In this case, the first groove is formed so as to extend over the entire width of the upright wall. In addition, it is preferable to form a notch for air release so as to divide a peripheral wall defining an outer periphery of the second groove and connect the inside of the second groove to the outside.

Only one annular second groove may be provided, or a plurality of annular second grooves may be provided concentrically with different diameters.

As described above, if the notch is provided so as to divide the peripheral wall defining the outer circumference of the second groove having an annular shape, when the insulating resin is cast into the case, the cut is formed. Because the air in the second groove can be evacuated through the notch,
It is possible to prevent the voids (bubbles) from being generated in the resin filled in the grooves, thereby preventing the insulating performance from being lowered. Since both ends of the first groove are open, there is no possibility that a void is generated in the resin filled therein.

[0018]

1 to 4 show examples of the configuration of an ignition coil according to the present invention. In these figures, reference numeral 1 denotes a primary bobbin made of a molded product of an insulating resin.
This primary bobbin is hollow and has one end 101 in the axial direction, similar to that used in a conventional ignition coil.
A cylindrical coil winding body 101 having flanges 102 and 103 near a and near the other end 101b, respectively, and a coil winding body from near one end 101a in the axial direction of the coil winding body 101. Standing wall 10 projecting outward in the radial direction
4 and a high-pressure cord holding portion 105 formed at the tip of the upright wall 104. High voltage cord holder 10
5 is a coil winding body 101 from the tip of the upright wall 104.
And a rear end located on the side of the upright wall 104 is closed by a bottom wall 105 a forming a part of the upright wall 104. The primary coil 3 is wound around the outer periphery of the coil winding body 101, and the terminal on the winding start side and the terminal on the winding end side of the primary coil 3 are on one end 101 a side of the coil winding body 101, respectively. And the other end 101b.

A secondary screw made of a tapping screw passes through a bottom wall 105a for closing the rear end of the high-voltage cord holding portion 105 of the primary bobbin 1 and has its tip directed toward the tip 105b of the high-pressure cord holding portion 105. The next terminal fitting 6 is attached. The tapping screw is attached by screwing into a prepared hole 105a1 that has been provided in a state where the bottom wall portion 105a of the high-voltage cord holding portion has been penetrated in advance.

The secondary bobbin 2 is provided with a large number of flanges 202, 202,... Arranged in the axial direction on the outer periphery of the cylindrical portion 201, like the one used in the conventional ignition coil. .. Are formed with coil winding grooves between them, and a series of coil winding grooves have unit coils 401, 40
Are wound, and these unit coils are sequentially connected in series to form a secondary coil 4. Secondary coil 4
Is connected to one end 2a of the secondary bobbin to the end of the primary coil 3 at the end of winding, and the terminal of the secondary coil at the end of winding is connected to the upright wall 104 of the primary bobbin. The secondary bobbin 2 is connected to a secondary terminal plate 9 attached to a thick flange portion 202 'provided at the other end 2b side (high pressure side) of the disposed secondary bobbin 2.

The secondary bobbin 2 around which the secondary coil 4 is wound is disposed so as to concentrically surround the coil winding body 101 of the primary bobbin, and is formed at both ends of the coil winding body 101. The secondary terminal plate 9 is fitted on the outer periphery of the flanges 102 and 103 so as to be in electrical contact with the rear end (head of the tapping screw) 6 a of the secondary terminal fitting 6.

The construction of each part is the same as that of the conventional ignition coil, but in the present invention, the coil winding body 10 is provided on the surface of the upright wall 104 of the primary bobbin 1 on the side of the secondary bobbin 2.
A plurality of first grooves 110 are formed in parallel with each other along the radial direction, and a second annular groove surrounding the rear end 6a is formed around the rear end 6a of the secondary terminal fitting 6. Groove 111
Is provided. As shown in FIG. 4, the first grooves 110 arranged in the radial direction of the coil winding body are formed so as to extend linearly over the entire width of the upright wall 104 and have both ends. It is open. Further, a pair of cut-out portions 112 for removing air is provided so as to divide a peripheral wall portion defining an outer periphery of the second groove 111 and communicate the inside of the second groove to the outside.
112 are formed.

A secondary bobbin on which the secondary coil 4 is wound, wherein the coil winding body 101 around which the primary coil 3 of the primary bobbin 1 is wound, the upright wall 104, and at least a part of the high-voltage cord holding section 105. 2 is inserted into a case 7, and a thermosetting insulating resin such as an epoxy resin is cast into the case 7 to form a resin mold portion 10.

Reference numeral 113 denotes a projection formed on the primary bobbin 1. The projection 113 contacts the inner surface of the case 7 to position the primary bobbin 1 in the case.

As described above, when the grooves 110 and 111 are provided on the surface of the upright wall 104 on the side of the secondary bobbin 2 where the high pressure cord holding portion of the primary bobbin is provided, the rear end portion 6a of the secondary terminal fitting 6 is connected to the primary terminal. Since the creepage insulation distance between the coil and the end on the side of the upright wall 104 can be increased, the secondary terminal fitting 6 and the end of the primary coil extend along the interface between the resin mold portion 10 and the upright wall 104. It is possible to prevent the occurrence of electric discharge between the first and second portions and the occurrence of dielectric breakdown.

When the grooves 110 and 111 were provided as shown in FIG. 1, the creepage insulation distance could be increased about 2.3 times as compared with the case where these grooves were not provided. In order to increase the creepage insulation distance, it is preferable to make the depth of the grooves 110 and 111 as deep as possible.

As described above, when the cutout portion 112 for bleeding air is provided so that the annular second groove 111 communicates with the outside, a liquid of an insulating resin such as an epoxy resin is poured into the case 7. At this time, since the air in the groove 111 can be removed through the cutout portion 112, the resin can be filled without leaving the air in the second groove 111. Therefore, it is possible to prevent voids from being generated in the resin filled in the groove 111, and to prevent a decrease in dielectric strength due to the voids. Since both ends of the first groove 110 are open, there is no possibility that voids will occur in the resin filled in the first groove.

In the above example, the upright wall 104 of the primary bobbin
Is provided on the surface on the secondary bobbin side in the width direction of the upright wall 104 (direction perpendicular to the direction in which the upright wall 104 protrudes). In addition, a second groove 111 surrounding the rear end portion of the secondary terminal fitting is provided. However, the dielectric strength against creeping discharge generated between the secondary terminal fitting and the end of the primary coil on the rising wall side is lower than before. In order to improve the above, at least one groove for extending the creepage insulation distance may be formed between the secondary terminal fitting and the end of the primary coil on the upright wall side. It is not necessary to form a groove.

In the above example, only the ignition coil is housed in the case 7, but the present invention is also applied to a case where at least a part of the circuit components constituting the ignition device together with the ignition coil is housed in the case 7. can do.

[0030]

As described above, according to the present invention, the rear end of the high-voltage cord holding portion and the end of the primary coil on the standing wall side are provided on the surface of the standing wall of the primary bobbin on the side of the secondary bobbin. Since the groove for increasing the creepage insulation distance between them is formed, it is possible to prevent the occurrence of electric discharge between the rear end of the high voltage terminal fitting and the primary coil and the occurrence of dielectric breakdown.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of the configuration of an ignition coil according to the present invention, in which a half thereof is sectioned.

FIG. 2 is a left side view showing the inside of the case by cutting only the case along the line AA in FIG. 1;

FIG. 3 is a top view showing the vicinity of a rear end of a high-voltage cord holding portion of the ignition coil of FIG. 1;

4 is a perspective view showing a state before attaching a secondary terminal fitting near a high-voltage cord holding portion of a primary bobbin used in the ignition coil of FIG. 1;

FIG. 5 is a front view showing a half of a conventional ignition coil.

FIG. 6 is a left side view showing only the ignition coil case of FIG. 5 in section along the line BB and showing the inside;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary bobbin 101 Coil winding trunk part 102, 103 Flange part 104 Upright wall 105 High voltage cord holding part 110 First groove 111 Second groove 112 Notch part 2 Secondary bobbin 3 Primary coil 4 Secondary coil 5 Iron core 6 Secondary terminal fitting 7 Case 9 Secondary terminal plate 10 Resin molded part

Claims (2)

[Claims] 1. A coil-shaped body for coil winding formed in a cylindrical shape, and an upright wall protruding radially outward of the body for coil winding from near one axial end of the body for coil winding. And a rear end portion located on the side of the upright wall, which is provided so as to protrude from a front end portion of the upright wall to a side opposite to the body portion for coil winding, and is closed by a bottom wall portion forming a part of the upright wall. A primary bobbin made of insulating resin integrally having a cylindrical high-voltage cord holding portion formed therein, and a bottom wall portion for closing a rear end portion of the high-voltage cord holding portion of the primary bobbin, and a front end of the high-voltage cord. A secondary terminal fitting attached in a state facing the distal end side of the holding portion, a primary coil wound around a coil winding body of the primary bobbin, and a coil winding body of the primary bobbin outside. Is wound around a secondary bobbin provided to surround from one end of the primary coil. A secondary coil connected to one end and the other end electrically connected to the rear end of the secondary terminal fitting, a coil winding body of the primary bobbin around which the primary coil is wound, and an upright wall. A case accommodating at least a part of the high-voltage cord holding portion together with the secondary bobbin around which the secondary coil is wound, wherein an insulating resin is cast into the case, and A groove for increasing a creepage insulation distance between a rear end of the high-voltage cord holding portion and an end of the primary coil on the upright wall side is formed on a surface of the upright wall of the primary bobbin on the side of the secondary bobbin. An ignition coil for an internal combustion engine, wherein the ignition coil is formed. 2. A coil winding body formed in a cylindrical shape and an upright wall protruding radially outside of the coil winding body from near one axial end of the coil winding body. And a bottom wall portion which is provided so as to protrude from the front end portion of the upright wall to the opposite side to the coil winding body portion and which is located on the upright wall side, forms a part of the upright wall. A primary bobbin made of insulating resin integrally having a closed cylindrical high-voltage cord holding portion, and a bottom wall that closes a rear end portion of the high-voltage cord holding portion of the primary bobbin; A secondary terminal fitting attached in a state facing the distal end side of the cord holding unit, a primary coil wound around a coil winding body of the primary bobbin, and a coil winding body of the primary bobbin. One end of the primary coil is wound around a secondary bobbin provided to surround from the outside. A secondary coil electrically connected to one end of the primary terminal and the other end electrically connected to a rear end of the secondary terminal fitting; and a coil winding body of a primary bobbin around which the primary coil is wound. A case in which a wall and at least a part of the high-voltage cord holding portion are accommodated together with a secondary bobbin around which the secondary coil is wound, and wherein an insulating resin is cast into the case. A plurality of first grooves arranged in a radial direction of the coil winding body on a surface of the upright wall of the primary bobbin on the secondary bobbin side, and surrounds a rear end of the secondary terminal fitting. Annular second
The first groove is formed so as to extend over the entire width of the upright wall, and the second groove is formed by dividing a peripheral wall defining an outer periphery of the second groove.
A cutout portion for venting air so that the inside of the groove communicates with the outside.