JP3341755B2 - Electromagnetic coil and ignition coil for internal combustion engine using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic coil, and is particularly suitable for an application used under a high voltage. For example, it is suitable for an ignition coil for an internal combustion engine that supplies ignition spark by inducing a high voltage.

[0002]

2. Description of the Related Art A conventional electromagnetic coil is disclosed in
There are known electromagnetic coils disclosed in JP-A-8572, JP-A-2-105310, and JP-A-60-107813. These prior arts propose an electromagnetic coil in which windings are stacked obliquely with respect to the axis of the spool. In the winding shape of such an electromagnetic coil, the winding layer forms a conical surface and spreads, and can be called oblique winding. Such obliquely wound electromagnetic coils can be distinguished from electromagnetic coils having classical columnar windings by the shape of the winding layer.

In such an obliquely wound electromagnetic coil, since a series of winding layers form a conical surface along a radial direction and spread,
The number of turns in one winding layer is small. This means that the number of turns between adjacent wires can be reduced. This allows
It is possible to reduce an electric potential difference generated between wires, prevent insulation breakdown between wires, and provide an electromagnetic coil suitable for use under high voltage. Such characteristics can be referred to as the withstand voltage performance or insulating property of the electromagnetic coil.

Such an obliquely wound electromagnetic coil is suitable for an ignition coil for an internal combustion engine, as disclosed in Japanese Patent Publication No. 2-18572 and Japanese Patent Application Laid-Open No. 60-107813. In particular, as disclosed in JP-A-60-107813, the present invention can be used for a secondary coil that generates a high voltage in combination with a primary coil.

[0005]

However, according to an experiment conducted by the present inventors to make the obliquely wound electromagnetic coil industrially usable, it is extremely difficult to obtain an obliquely wound wire in which wires are perfectly aligned. Turned out to be. In particular, in industrial use, an automatic winding machine that turns coils into wires at high speed is used, and it is necessary to wind thin wires in order to meet the demand for miniaturization and weight reduction. It is extremely difficult to achieve counter-winding.

In particular, in the case of oblique winding, winding collapse sometimes becomes large in the latter half of the winding. In addition, the end of winding may collapse due to variations in tension applied to the wire during winding or variations in the axial length of the spool. In addition, when a spool is used, the winding may enter the groove for taking out the winding end formed in the flange at the end of the spool, causing winding disturbance.

As described above, if the oblique winding includes a winding disorder such as a broken portion, there is a chance that wires having a large potential difference are adjacent to each other, and it becomes difficult to predict and manage the potential difference between the wires. For this reason, there has been a problem that it is difficult to realize high insulation properties expected of the obliquely wound electromagnetic coil. An object of the present invention is to provide an electromagnetic coil capable of exhibiting excellent insulating properties by reducing winding collapse of an obliquely wound electromagnetic coil. Another object of the present invention is to improve the insulation of a secondary coil of an ignition coil for an internal combustion engine.

[0008]

According to the electromagnetic coil according to the first aspect of the present invention, since the flange at the end of the oblique winding is formed with an obtuse angle, the electromagnetic coil is manufactured by the slope formed by the flange. The above error can be absorbed, and the generation of the gap and the bulging of the wire can be prevented.

[0009] According to claim 2, 3 Symbol mounting of the electromagnetic coil of the present invention, since to prevent the protrusion of the opening of the winding can be prevented collapse winding to prevent deformation of the winding. According to the ignition coil for an internal combustion engine according to claim 4 Symbol mounting of the present invention can be applied for insulation between wires of the electromagnetic coil is good, stable and high voltage to the spark plug is used as a secondary coil. According to the electromagnetic coil of claim 5 of the present invention, the oblique direction
Facing the winding of the flange at the end of winding
Surface is at an obtuse angle to the axis.
Absorbs manufacturing errors due to the slope facing the winding part,
It is possible to prevent gaps and swelling of the wire rod from occurring.
Wear.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment showing an embodiment of the present invention will be described below with reference to FIGS. The embodiment described below is an improved ignition coil for an internal combustion engine. In the embodiment described below, the obliquely wound windings are illustrated and described as being completely aligned. However, an unacceptable and unacceptable amount of winding collapse occurs in the production by an automatic winding machine.

As shown in FIG. 2, the ignition coil 2 mainly comprises a cylindrical transformer section 5 and a control circuit section 7 which is located at one end of the transformer section 5 and intermits the primary current of the transformer section 5. And a connection section 6 located at the other end of the transformer section 5 and supplying a secondary voltage of the transformer section 5 to a spark plug (not shown).

The ignition coil 2 has a cylindrical case 100 made of a resin material, which is a housing for the ignition coil 2. A high-voltage generating chamber 102 is formed in a housing chamber 102 formed inside the case 100. Of the transformer section 5, the control circuit section 7, and the insulating oil 29 filling the periphery of the transformer section 5. A control signal input connector 9 is provided at an upper end of the storage chamber 102, and a bottom 104 closed by a bottom of a cup 15 described later is formed at a lower end of the storage chamber 102. The outer peripheral wall of this cup 15
It is covered by the connection part 6 located at the lower end of the case 100.

The connecting portion 6 is formed by a case 100 with a cylindrical portion 105 for accommodating an unillustrated ignition plug, and a plug cap 13 made of rubber is mounted on an open end of the cylindrical portion 105. A metal cup 15 is insert-molded in a resin material of the case 100 at a bottom portion 104 located at an upper end of the cylindrical portion 105. For this reason, the accommodation room 102 and the connection part 6 are liquid-tightly partitioned. The spring 17 locked to the bottom of the cup 15 is formed of a compression coil spring, and the electrode of a spark plug (not shown) inserted into the connection portion 6 is electrically connected to the other end of the spring 17. Has become.

The control signal input connector 9 comprises a connector housing 18 and connector pins 19. The connector housing 18 is integrally formed with the case 100, and three connector pins 19 located in the connector housing 18 are insert-molded in the connector housing 18 so as to penetrate the case 100 and be connectable to the outside.

On the upper side of the case 100, a transformer unit 5,
An opening 100a for accommodating the control circuit 7, the insulating oil 29, and the like in the accommodation chamber 102 from outside the case 100 is formed. The opening 100 a is closed by a metal lid 33 being caulked and fixed to the upper part of the case 100.
An O-ring 32 for liquid tightness is provided between the lid 33 and the case 100.
Is interposed.

The transformer unit 5 includes an iron core 502, a magnet 50
4, 506, secondary spool 510, secondary coil 512,
It comprises a primary spool 514 and a primary coil 516. The columnar iron core 502 is assembled by stacking thin silicon steel plates so as to have a substantially circular cross section. Magnets 504, 50 having polarities opposite to the direction of the magnetic flux generated by excitation of the coil are provided at both ends of the iron core 502.
6 are each fixed by an adhesive tape.

The secondary spool 510 as a bobbin has flanges 510a, 510b at both ends and flanges 510a, 51b.
It is a resin molded product formed into a bottomed cylindrical shape having a winding portion 530 between 0b, and a lower end portion is substantially closed by a bottom portion 510c. On the bottom 510c of the secondary spool 510,
A terminal plate 34 to which a lead wire (not shown) drawn from one end of the secondary coil 512 is electrically connected is fixed, and a spring 27 for contacting the cup 15 is fixed to the terminal plate 34. The terminal plate 34 and the spring 27 function as a spool-side conductive member, and the high voltage induced in the secondary coil 512 causes the terminal plate 34, the spring 27,
It is supplied to an electrode portion of a not-shown ignition plug via a cup 15 and a spring 17.

The opposite bottom portion 510 of the secondary spool 510
At the end on the c side, a cylindrical portion 51 is concentric with the secondary spool 510.
0f is formed to extend. This secondary spool 51
0, the iron core 502 and the magnet 506 are accommodated therein, and the outer periphery of the secondary spool 510, that is, the winding portion 530
, A secondary coil 512 wound by a winding method described later is located.

The primary spool 514, which is a resin molded product,
It is formed in a bottomed cylindrical shape having flanges 514a and 514b at both ends, and the upper end is substantially closed by a lid 514c. A primary coil 516 is wound around the outer periphery of the primary spool 514. In the lid portion 514c of the primary spool 514, a cylindrical portion 514f extending toward the lower end of the primary spool 514 is formed concentrically with the primary spool 514, and an opening 514d is formed. The cylindrical portion 514f is formed so as to be concentrically located inside the cylindrical portion 510f of the secondary spool 510 when the secondary spool 510 and the primary spool 514 are assembled. Therefore, when assembling the primary spool 514 and the secondary spool 510, the cover 5 of the primary spool 514
14c and the bottom 510c of the secondary spool 510,
An iron core 502 having magnets 504 and 506 at both ends is sandwiched.

An auxiliary core 508 having a slit (not shown) is mounted outside the primary spool 514 around which the primary coil 516 is wound. This auxiliary core 508 is
A thin silicon steel sheet is wound in a cylindrical shape, and a slit is formed in the axial direction because a winding start end and a winding end end are not connected.
6 having an axial length extending over the outer peripheral position. Thereby, the short-circuit current generated in the circumferential direction of the auxiliary core 508 is reduced.

An accommodation room 1 in which a transformer unit 5 and the like are accommodated.
02 is filled with insulating oil 29 leaving a slight air space at the upper end of the accommodation chamber 102. The insulating oil 29 is provided at the lower opening end of the primary spool 514, an opening 514 d formed substantially at the center of the lid 514 c of the primary spool 514,
It penetrates through the upper opening end of the secondary spool 510 and an opening (not shown) to ensure electrical insulation between the iron core 502, the secondary coil 512, the primary coil 516, the auxiliary core 508, and the like.

Here, the configuration of the secondary coil 512 will be described with reference to FIG. As shown in FIG.
The secondary coil 512 wound around the ten winding units 530 includes:
For example, the wire 520 whose outer periphery is covered with an insulating film made of amide imide is wound 16,000 times by oblique double winding. The reason why the total number of turns of the secondary coil 512 is 16000 is that the secondary voltage determined by the turns ratio between the primary coil 516 and the secondary coil 512 is a voltage at which spark discharge of a spark plug (not shown) is possible.
This is for setting to kV. The maximum outer diameter of the wire 520 is set to, for example, 0.07 mm including the thickness of the insulating film, and the axial length of the winding part 530 around which the wire 520 is wound is set to, for example, 61.5 mm. ing. The material of the insulating film of the wire 520 may be urethane, polyesterimide, or the like, in addition to amide imide.

The winding portion 530 extends continuously along the axial direction of the secondary spool 510, and has no partition. At both ends of the secondary spool 510, flange portions 510a and 510b as flange portions are formed. The flange portion 510b is located on the winding end side, and its surface facing the winding portion 530 has an obtuse angle θ with respect to the axis of the coil.
Is formed. Where θ = 100 °
It is. Therefore, the flange portion 510b has a shape that spreads like a flare.

The collar 510b prevents the winding from breaking at the winding end. That is, due to the axial length of the secondary spool 510 being long or the tension of the wire in the winding process being too large, etc.
It is assumed that a gap remains at the end of winding as shown in FIG. 7, but the slope 540 of the flange 510b can prevent or reduce the gap. Also,
It is assumed that the winding of the secondary spool 510 is short at the end of the winding due to the axial length being short or the tension of the wire in the winding process being too small. The slope 540 of the portion 510b can eliminate or reduce the swelling of the winding. Therefore, by forming the flange portion 510b in a flared shape, it is possible to suppress the occurrence of the gap at the winding end portion and the occurrence of swelling of the winding, which may cause the winding collapse, thereby preventing the winding collapse in a later stage of the winding process. Can be. In particular, in this embodiment, since the high voltage side as the ignition coil is set as the winding end side, it is possible to prevent winding collapse on this high voltage side and secure high insulation.

Further, the flange 510b is formed with an opening through which the end on the winding end side of the wire, that is, the end on the high voltage side is drawn out of the secondary spool 510. This opening is formed as a groove 541 extending from the outer peripheral edge of the flange 510b. The groove 541 is formed at a position higher than the winding height of the winding in contact with the flange 510b. As a result, of the slope 540, the area in contact with the wire becomes a conical surface that is continuous in the circumferential direction. Therefore, the winding is not pushed out to the opening, and the winding can maintain a substantially perfect circle. This prevents the winding from collapsing. On the other hand, as shown in FIG.
If the height is lower than the winding height of the winding, for example, over the entire height of the flange portion 510b, the winding is pushed out to the opening and the winding shape of the winding is disturbed, which causes winding collapse.

In the embodiment described above, the winding start portion is formed by random winding reciprocating in the axial direction. When the turbulent winding forms a triangular turbulent winding portion 531 at the winding start portion, thereafter, oblique heavy winding aligned to the winding end portion is performed. The turbulent winding is formed by an automatic winding machine in the same manner as the oblique heavy winding, and the winding is performed exclusively for the purpose of creating a reference slope without breaking the winding. The turbulent winding is not intended to align the wires, but rather moves the wires randomly in the axial direction and stacks the wires in a triangular cross section, making it relatively easy to create a slope to start oblique winding. Moreover, it can be made by the turbulent winding portion 531 which is hard to collapse. The irregular turbulent portion 531 thus formed
Is set to the low voltage side when used as an ignition coil, the potential difference between the wires in the turbulent winding portion 531 becomes relatively low, so that the withstand voltage and the insulation are not significantly reduced.

Further, in this embodiment described above, an example in which the electromagnetic coil of the present invention is applied to a secondary coil of an ignition coil for an internal combustion engine has been described. In addition, by applying the electromagnetic coil of the present invention to an electromagnetic coil to which a relatively high voltage is applied, good withstand voltage and insulation can be exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method of winding an obliquely wound coil according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an ignition coil for an internal combustion engine to which the obliquely wound coil of the present embodiment is assembled.

FIG. 3 is a schematic view showing a state of a winding end portion of a comparative example with respect to the present embodiment.

FIG. 4 is a schematic diagram showing a state in a winding take-out part of a comparative example with respect to the present embodiment.

[Explanation of symbols]

 2 Ignition coil 5 Transformer part 6 Connection part 100 Case 510 Secondary spool (bobbin) 510a, 510b Flange part (flange part) 512 Secondary coil 514 Primary spool 516 Primary coil 520 Wire rod 530 Winding part 531 Disturbance winding part 541 Groove ( Aperture)

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Katsumi Nakazawa 1-1-1, Showa-cho, Kariya-shi, Aichi Pref. DENSO Corporation (56) References (JP, U) JP-A 4-51118 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 38/12 H01F 27/28 H01F 27/32

Claims (5)

(57) [Claims] 1. An electromagnetic coil formed by winding a wire on an axis, wherein the wire forms a winding layer along a slope inclined with respect to the axis, and a plurality of the winding layers are laminated. An electromagnetic coil, comprising: a spool having oblique winding and having a flange located at an end on the winding end side, wherein the flange forms an obtuse angle with respect to the axis. 2. An opening for taking out an end of a wire is formed in the flange, and the opening is opened at a position higher than a winding height of the wire in contact with the flange. 2. The electromagnetic coil according to claim 1, wherein: 3. The electromagnetic coil according to claim 2, wherein the opening is a groove extending from an outer peripheral edge of the flange. 4. An ignition coil for an internal combustion engine, wherein the electromagnetic coil according to claim 1, 2 or 3 is used as a secondary coil. (5) Electromagnetic coil formed by winding a wire on an axis
At The wire rod has a winding layer along a slope inclined with respect to the axis.
And a plurality of the winding layers are laminated to form a diagonal winding.
Is forming, Sp with a flange located at the end on the winding end side
And a surface of the flange portion facing the winding portion.
Has an obtuse angle with respect to the axis.
Electromagnetic coil.