JPH1167563A - Ignition coil in internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition in an internal combustion engine, in which a cylindrical outer core is provided at a given place and held appropriately. SOLUTION: A housing is so constituted that an upper end part 61a of a cylindrical lower case 61 is fitted to an opening of a cylindrical lower end part 62b of an upper case 62. An outer core 30 is fitted to the outer face of the lower case 61, and the upper end part of the outer core 30 is held between the lower end part 62b of the upper case 62 and the upper end part 61a of the lower case 61. The lower end part 62b of the upper case 62 has an annular groove 62b on its inner wall. The outer core 30 is preferably held by fitting it to the outer face of the lower case 62, while the upper end part of the outer core 30 is fitted to the annular groove 62d. In addition, the lower end part 61b of the lower case 61 preferably has a step part 61g to be fitted to the lower end part of the outer core 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil for an internal combustion engine, and more particularly to an ignition coil for an internal combustion engine in which an inner core, a primary coil and a secondary coil are housed in a housing and a cylindrical outer core is mounted on the housing. Related.

[0002]

2. Description of the Related Art Recently, there has been a demand for the development of an ignition coil for an internal combustion engine which is small and easy to wire and assemble. For example, JP-A-8-3
Japanese Patent No. 35523 discloses an ignition coil having a columnar core having a substantially circular cross section in the radial direction. In the ignition coil disclosed in the publication, a transformer section including an iron core, a magnet, a secondary spool, a secondary coil, a primary spool, and a primary coil is housed in a case together with a control circuit section, and insulating oil is injected. After that, the lid is caulked and fixed to the opening. In particular, the iron core is formed by laminating a plurality of magnetic steel plates having different plate width dimensions into a columnar shape having a substantially circular cross section.

On the other hand, Japanese Patent Application Laid-Open No. Hei 8-339931 discloses that a housing comprises a first case and a second case, in which a primary coil, a secondary coil and a secondary terminal are accommodated in a first case. After supporting the high-pressure terminal in the second case, the first case and the second case are joined to connect the secondary terminal and the high-voltage terminal, and the first and second cases are connected through the opening on the side surface of the first case. An ignition coil for an internal combustion engine configured to fill a case with a synthetic resin is disclosed.

[0004]

Problems to be Solved by the Invention JP-A-8-33 mentioned above
In the ignition coil described in Japanese Patent No. 5523, a transformer and a control circuit are accommodated in a single case (housing), and furthermore, insulating oil is injected into the case.
Therefore, the case is required to be liquid-tight, and a special structure for that purpose has been proposed. Since the outer core is housed in the case, the dimension in the radial direction is necessarily large in order to secure a predetermined gap between the outer core and the secondary coil.

In Japanese Patent Application Laid-Open No. Hei 8-339931, the housing is divided into a first case and a second case, and the outer core is built in the wall of the upper first case. For this reason, the first case portion becomes large, and a step of incorporating the outer core in the first case is also required. On the other hand, the outer core may be configured to be fitted to the outside of the housing. However, it is necessary to arrange the outer core at a predetermined position in relation to the primary coil, the secondary coil, and the like, and hold the outer core appropriately.

Accordingly, the present invention provides an ignition coil for an internal combustion engine in which an inner core, a primary coil, and a secondary coil are housed in a housing and a cylindrical outer core is mounted on the housing, wherein the outer core is arranged at a predetermined position of the housing. It is another object of the present invention to provide an ignition coil for an internal combustion engine that can be appropriately held.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an ignition system for an internal combustion engine in which an inner core, a primary coil and a secondary coil are housed in a housing and a cylindrical outer core is mounted on the housing. In the coil, the housing includes a cylindrical lower case for mounting the outer core and an upper case having a cylindrical lower end, and an upper end of the lower case is fitted into an opening on a lower end side of the upper case. The outer core is fitted to the outer surface of the lower case, and the upper end of the outer core is sandwiched between the lower end of the upper case and the upper end of the lower case.

The present invention also relates to an ignition coil for an internal combustion engine, wherein a secondary coil is wound around a columnar inner core, accommodated in a housing together with a cylindrical primary coil, and a cylindrical outer core is mounted on the housing. The housing is
An upper case having a cylindrical lower case and a cylindrical lower end is provided, and an upper end of the lower case is fitted to an opening on a lower end side of the upper case,
A permanent magnet disposed at both axial ends of the inner core; the permanent magnet is housed in the lower case together with the inner core; the outer core is fitted to an outer surface of the lower case; The upper core may be disposed so as to be substantially at the same position as the upper end of the magnet in the axial direction, and the upper end of the outer core may be sandwiched between the lower end of the upper case and the upper end of the lower case.

[0009] The outer core may be disposed so that the lower end of the outer core is located between a position substantially the same as the lower end of the permanent magnet and a position located a predetermined distance above in the axial direction.

In the ignition coil for an internal combustion engine, a step may be formed at a lower end of the lower case, and the lower end of the outer core may be locked to the step.

In the ignition coil for an internal combustion engine, an annular groove which opens downward is formed in an inner wall of a lower end of the upper case, and the outer core is fitted to an outer surface of the lower case, and an upper end of the outer core is formed. May be configured to fit into the annular groove of the upper case.

Further, in the ignition coil for an internal combustion engine, the winding of the primary coil is fitted into the lower case in a state of being wound in a cylindrical shape, and the upper end of the outer core and the upper end of the primary coil are fixed to the lower case. You may comprise so that it may be clamped between the lower end part of an upper case and the upper end part of the said lower case.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an ignition coil for an internal combustion engine according to the present invention will be described below with reference to the drawings. 1 and 2 show a cross section of an ignition coil for an internal combustion engine according to one embodiment of the present invention. A housing 60 is a synthetic resin container-like housing in which a lower case 61 and an upper case 62 are joined. The cylindrical lower end portion 62b of the case 62
The lower opening 61 is configured to fit the cylindrical upper end 61a into the opening on the side. The upper end 62a of the upper case 62 is a housing in which the igniter 8 is housed. A stepped annular groove 62d is formed inside the lower end 62b of the upper case 62. 5 shows an enlarged view of the lower end 62b of the upper case 62, and FIG. 6 shows an enlarged view of the lower end 61b of the lower case 61.

As shown in FIGS. 1 and 2, the lower case 61 houses the primary coil 12 and the secondary coil assembly 20, and the outer core 30 is mounted outside the lower case 61. A high-voltage terminal 61c is formed continuously with the lower end 61b of the lower case 61. The high-voltage terminal 61c has a built-in high-voltage terminal 7, and a plug cap 70 formed of an insulating material (for example, rubber) in a cylindrical shape is mounted outside the high-voltage terminal 61c.

The primary coil 12 is fitted in the lower case 61 with the winding wound in two or four layers. A step 61f is formed on the inner periphery of the lower end 61b of the lower case 61, and the primary coil 12 is locked to the step 61f. An insulating film 40 having a releasability from an epoxy resin or the like as an insulating material covers the inner surface of the primary coil 12 and is provided so as to extend in the axial direction above and below the primary coil 12. An annular groove 61d is formed on the inner surface of the lower end 61b of the lower case 61 so as to open upward. The lower end of the insulating film 40 is housed in the groove 61d, and is covered by the wall 61e. On the other hand, above the primary coil 12, an elastic member (for example, sponge rubber) B2 is filled between the upper end 61a of the lower case 61 and the upper end of the insulating film 40.

The outer core 30 is formed of a silicon steel plate in a cylindrical shape as shown in FIGS.
When fitted to the outside of the lower case 61 of the housing 60, the slit 31 is formed in the axial direction. An annular step 61g is formed on the outer periphery at the same position as the step 61f of the lower end 61b of the lower case 61,
The end of the outer core 30 is locked to the step 61g. When the upper case 62 is assembled to the lower case 61, for example, as shown in FIG.
The gap G is formed between d and the upper end of the outer core 30. FIG. 2 shows a case where the arrangement is different from that of FIG. 1 at the time of assembly, and a gap G is formed between the lower end of the outer core 30 and the step portion 61 g of the lower case 61.

The secondary coil assembly 20 is shown in FIGS.
As shown in FIG. 8, the secondary coil 22 is attached to the secondary bobbin 21.
Is wound, and a hollow portion of the secondary bobbin 21 accommodates the columnar inner core 10 and a pair of permanent magnets (represented by 50). As shown in FIG. 2, the inner core 10 of the present embodiment is formed by stacking a plurality of flat plates of a magnetic material, for example, silicon steel plates, and is formed in a columnar shape. The secondary bobbin 21 has a plurality of flanges (represented by 21a at regular intervals) in the axial direction.
Are formed in a resin-made cylindrical body.
The windings of the secondary coil 22 are sequentially wound in a plurality of annular grooves formed between a.

As shown in FIGS. 1 and 2, the inner core 1
Column-shaped permanent magnets 50 are disposed at both ends in the axial direction of 0, and elastic members (for example, sponge rubber) B1 are attached to both ends. A plurality of projections 21c are formed on the inner surface of the lower end of the secondary bobbin 21, and the permanent magnet 50 and the inner core 10 are supported on the projections 21c via the elastic member B1. A pair of permanent magnets 50
Are arranged so that the directions of the generated magnetic fluxes are the same, and opposite to the direction of the magnetic flux formed in the inner core 10 when the primary coil 12 is energized. Thus, the above-described inner core 10, permanent magnet 50, and outer core 30 form a magnetic circuit.

As shown in FIG. 2, the axial lengths of the inner core 10, the primary coil 12, and the secondary coil 22 are set to the same length L. In particular, the axial length of the inner core 10 is set to be substantially the same as the axial length of the secondary coil 22 so that the amount of change in magnetic flux linked to the secondary coil 22 is maximized. Inner core 10 as long as it is satisfied
May be larger than the axial length of the secondary coil 22.

With the inner core 10, the primary coil 12 and the secondary coil 22 housed in the lower case 61, the outer core 30 has an end face (lower end in FIG. 1) on the high voltage terminal 7 side from the lower end of the permanent magnet 50. It is desirable that the upper end is set within a range of a predetermined distance D (for example, 5 mm). In the present embodiment, the lower end of the outer core 30 and the lower end of the primary coil 12 can be matched as shown in FIG. . In other words, in FIG. 1, the lower end of the outer core 30 is located above the lower end of the permanent magnet 50 by the thickness (for example, 4 mm) of the permanent magnet 50, and the predetermined distance D
(5 mm). Then, as shown in FIG. 2, even if the outer core 30 moves the distance of the gap G in the axial direction, it is set so as to be within a range of a predetermined distance D (5 mm) from the lower end of the permanent magnet 50. Thereby, the electric field concentration at the lower end of the outer core 30 due to the high voltage generated in the secondary coil 22 can be avoided while increasing the amount of change in magnetic flux generated when the primary coil 12 is energized.

As shown in FIGS. 1, 2, 8, 9, and 11, a holding portion 21e is formed at the upper end of the secondary bobbin 21, and the secondary terminal 18 is supported by the holding portion 21e. The low voltage side of the secondary coil 22 is connected to this. That is, as shown in FIG. 11, the end of the winding of the secondary coil 22 on the low pressure side is led out from the axial groove 21 f of the flange 21 a, and after being wound several times around the upper end of the secondary bobbin 21, It is wound around the base end of the secondary terminal 18.

On the other hand, as shown in FIGS. 1, 2, 6, 8, 10, and 12, a secondary terminal 17 on the high-pressure side is mounted at the lower end of the secondary bobbin 21. The secondary terminal 17 is formed by bending a plate made of a conductive material into a U-shape, and as shown in FIG.
A hole 17a having an engagement projection is formed, and the tip of the high-voltage terminal 7 is engaged with the hole 17a. The pair of legs 17d of the secondary terminal 17 is engaged with a pair of grooves 21d formed on the lower end surface of the secondary bobbin 21. A connecting portion 17c extends laterally from the substrate portion 17b, and the high-voltage end of the winding of the secondary coil 22 is wound around the connecting portion 17c. Then, after the solder is attached as necessary, the connection portion 17c is bent so as to be parallel to the axis of the secondary bobbin 21 (the state after bending is shown by a solid line in FIG. 8, and the state before bending is shown in FIG. 8). (Indicated by dashed lines).

A connector portion 62c is formed integrally with the upper case 62 of the housing 60. The connector portion 62 has a connector terminal 63 as shown in FIG.
a to 63d are arranged in parallel. The base end sides of these connector terminals 63a to 63d are connected to igniter terminals 8a to 8d shown in FIG. 3, and the igniter 8 is configured so that the power supply to the primary coil 12 is intermittently controlled. The connector terminal 63a is grounded, and the connector terminal 63d is connected to a power supply (not shown). The base end of the latter is connected to the igniter terminal 8d and the winding start side of the primary coil 12 together with the igniter terminal 8d. I have. Further, the igniter 8 is provided with igniter terminals 8e and 8f, which are connected to connection terminals 63e and 63f indicated by broken lines in FIG. The diode 9 is connected between the connection terminal 63f and the secondary terminal 18.

In manufacturing and assembling the ignition coil having the above-described configuration, first, a plurality of silicon steel plates are laminated to form the inner core 10 shown in FIGS. Secondary terminals 17 and 18 are attached to both ends of the secondary bobbin 21, and a secondary coil 22 is wound around the secondary bobbin 21, and the winding of the secondary coil 22 is connected to the secondary terminals 17 and 18.
Is electrically connected to The permanent magnets 50 are attached to both ends of the inner core 10 in the axial direction, and the elastic members B
1 are adhered and formed, and these are accommodated in the hollow portion of the secondary bobbin 21 to form the secondary coil assembly 20.
At this time, the elastic member B1 makes point contact with the plurality of protrusions 21c, and the inner core 10 and the permanent magnet 50 are supported by the protrusions 21c via the elastic member B1. Thus, the inner core 10 and the permanent magnet 50 are in a state of being surrounded by the secondary bobbin 21.

On the other hand, the outer core 30 is formed in a cylindrical shape by a silicon steel plate and is pressed into the outside of the lower case 61 of the housing 60, or the silicon steel plate is wound around the lower case 61. Primary coil 1 in lower case 61
2 are accommodated, and an insulating film 4 is provided inside the primary coil 12.
0 is provided. At this time, as shown in FIG. 1, the gap G is provided between the stepped annular groove 62d of the lower end portion 62b of the upper case 62 and the upper end of the outer core 30 so as to form a gap G in FIG. 30 moves in the axial direction,
A gap G is formed between the lower end and the step 61g). An elastic member (for example, sponge rubber) B2 is filled above the primary coil 12 between the upper end 61a of the lower case 61 and the upper end of the insulating film 40.

Then, the secondary coil assembly 20 is housed in the housing 60, and the high-voltage terminal 61c
When the high pressure terminal 7 is press-fitted into the secondary terminal 1
7 is electrically connected. 3 and 4, the winding end of the primary coil 12 is connected to the connection terminal 63e, the winding start is connected to the connector terminal 63d, and the igniter 8 is connected to the upper case 62 of the housing 60. Are accommodated, and the igniter terminals 8a to 8f are respectively connected to the terminals 63a to 63f.
f. Thus, the low voltage side of the winding of the secondary coil 22 is connected to the igniter 8 via the secondary terminal 18, the diode 9, the connection terminal 63f and the igniter terminal 8f, and the high voltage side is connected to the high voltage via the secondary terminal 17. Connected to terminal 7.

The lower case 61 assembled as described above.
Is fitted to the upper case 62. That is, the lower case 6
1, the upper end portion 61a, the primary coil 12, and the outer core 30
Are fitted into the stepped annular groove 62d of the upper case 62, and the primary coil 12 and the outer core 30 are respectively fitted to the lower case 61.
Are supported between the stepped portions 61f and 61g and the stepped annular groove 62d of the upper case 62. Thereby, FIGS. 1 and 5
2, a gap G is formed between the outer core 30 and one step of the stepped annular groove 62d (or between the outer core 30 and the step 61g as shown in FIG. 2). At the same time, the primary coil 12 is sandwiched between the stepped portion 61f of the lower case 61 and another stepped portion of the stepped annular groove 62d of the upper case 62 together with the elastic member B2.

Therefore, the outer core 30 is supported between one step of the stepped annular groove 62d and the step 61f outside the lower case 61, and the other step of the stepped annular groove 62d and the lower case 61 Elastic member B between inner step 61g
2, the primary coil 12 is supported. At this time, the upper end of the insulating film 40 is attached to the wall 62 e of the upper case 62.
The lower end of the insulating film 40 is
Is covered with the wall portion 61e.

Then, the space inside the housing 60 is filled with epoxy resin as an insulating material and cured, and the insulating portion 13 is formed in the lower case 61 as shown by stippling in FIGS. 13 is omitted in the drawing).
As a result, the primary coil 12 and the secondary coil 22 are impregnated and fixed, the electrical connection portion is appropriately insulated, and the electrical insulation that can withstand the output high voltage of the secondary coil 22 is secured.

In particular, the permanent magnet 5 is provided by the secondary bobbin 21.
0 is surrounded and the joint between the end face of the inner core 10 and the permanent magnet 50 is also surrounded, so that the insulating portion 13 made of epoxy resin is not damaged. Further, since the insulating film 40 has releasability from the insulating portion 13, the primary coil 1
Even if there is a difference between the coefficient of thermal expansion such as 2 and the coefficient of thermal expansion of the insulating portion 13, the insulating portion 13 will not be damaged. In addition, since the upper end of the insulating film 40 is covered by the wall 62e and the lower end is covered by the wall 61e, the insulating film 40
Are not in direct contact with the insulating portion 13.

In the ignition coil for an internal combustion engine according to this embodiment having the above-described configuration, the plug cap 70 is mounted on the lower case 61 outside the high-voltage terminal portion 61c. Via this plug cap 70, it is attached to an internal combustion engine (not shown) and connected to an ignition plug (not shown). When the primary current of the primary coil 12 is interrupted in this state, a counter electromotive force is induced in the secondary coil 22 to generate a high voltage of 30 to 40 kv, which is output to the ignition plug. As a result, spark discharge occurs in the electrode portion of each ignition plug, and the compressed air-fuel mixture in each combustion chamber (not shown) is ignited.

[0032]

Since the present invention is configured as described above, the following effects can be obtained. That is, in the ignition coil for an internal combustion engine of the present invention, the housing is configured to fit the upper end of the cylindrical lower case into the opening on the cylindrical lower end side of the upper case, and the outer core is connected to the lower case. Since the outer core is fitted to the outer surface and the upper end of the outer core is sandwiched between the lower end of the upper case and the upper end of the lower case, the outer core can be disposed at a predetermined position of the housing and appropriately held. Thus, the ignition coil can be reduced in size while maintaining the predetermined ignition performance.

Further, according to the structure as described in claim 6, the primary coil can be appropriately held simultaneously with the holding of the outer core.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an ignition coil for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of an ignition coil for an internal combustion engine according to one embodiment of the present invention.

FIG. 3 is a plan view of an ignition coil for an internal combustion engine according to one embodiment of the present invention.

FIG. 4 is a plan view showing a state in which an igniter is removed from the ignition coil for an internal combustion engine according to the embodiment of the present invention.

FIG. 5 is an enlarged longitudinal sectional view showing an end on the low pressure side of the ignition coil for an internal combustion engine according to one embodiment of the present invention.

FIG. 6 is an enlarged longitudinal sectional view showing an end on the high pressure side of the ignition coil for an internal combustion engine according to one embodiment of the present invention.

7 is a cross-sectional view of a coil portion of the ignition coil for an internal combustion engine according to one embodiment of the present invention, which is a cross-sectional view taken along line AA of FIG. 2;

FIG. 8 is a front view of a secondary coil assembly according to the embodiment of the present invention.

FIG. 9 is an enlarged plan view showing an end on the low pressure side of the secondary coil assembly according to the embodiment of the present invention.

FIG. 10 is an enlarged plan view showing an end on the high voltage side of the secondary coil assembly according to the embodiment of the present invention.

FIG. 11 is an enlarged side view showing an end on the low pressure side of the secondary coil assembly according to the embodiment of the present invention.

FIG. 12 is an enlarged side view showing a high-pressure side end of the secondary coil assembly according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 8 igniter 10 inner core 12 primary coil 13 insulating part 17, 18 secondary terminal 20 secondary coil assembly 21 secondary bobbin 22 secondary coil 30 outer core 40 insulating film 50 permanent magnet 60 housing 61 lower case 62 upper case

Claims (6)

[Claims] 1. An ignition coil for an internal combustion engine in which an inner core, a primary coil and a secondary coil are housed in a housing, and a cylindrical outer core is mounted on the housing, wherein the housing has a cylindrical lower case on which the outer core is mounted. And an upper case having a cylindrical lower end. The upper case is configured to fit an upper end of the lower case into an opening on a lower end side of the upper case, and the outer core is fitted to an outer surface of the lower case. An ignition coil for an internal combustion engine, wherein an upper end of the outer core is sandwiched between a lower end of the upper case and an upper end of the lower case. 2. An ignition coil for an internal combustion engine in which a secondary coil is wound around a columnar inner core, accommodated in a housing together with a cylindrical primary coil, and a cylindrical outer core is mounted on the housing. A lower case and an upper case having a cylindrical lower end,
An upper end of the lower case is fitted into an opening on a lower end side of the upper case, and permanent magnets are provided at both axial ends of the inner core. Housed in the lower case,
The outer core is fitted on the outer surface of the lower case, and at least the upper end of the outer core is disposed so as to be substantially at the same position in the axial direction as the upper end of the permanent magnet. An ignition coil for an internal combustion engine, wherein the ignition coil is configured to be sandwiched between a portion and an upper end portion of the lower case. 3. The outer core is disposed such that the lower end of the outer core is located between a position substantially the same as the lower end of the permanent magnet and a position located a predetermined distance upward in the axial direction. 3. The ignition coil for an internal combustion engine according to 2. 4. An ignition coil for an internal combustion engine according to claim 1, wherein a step is formed at a lower end of said lower case, and a lower end of said outer core is locked to said step. . 5. An annular groove which opens downward on an inner wall of a lower end of the upper case, the outer core is fitted to an outer surface of the lower case, and an upper end of the outer core is fitted into an annular groove of the upper case. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the ignition coil is configured to be fitted. 6. A state in which the winding of the primary coil is fitted into the lower case while being wound in a cylindrical shape, and the upper end of the outer core and the upper end of the primary coil are connected to the lower end of the upper case and the lower case. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the ignition coil is sandwiched between upper ends of the ignition coil.