JP2597869B2 - Manufacturing method of ignition coil - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an ignition coil for an internal combustion engine,
More specifically, the present invention relates to a method for manufacturing an ignition coil in which ignition performance is improved by generating a magnetic flux in a direction opposite to a magnetic flux generated when a primary coil is energized by inserting a permanent magnet into a core.

(Prior Art) As is well known, a conventional ignition coil of an internal combustion engine is formed of a core (iron core) in which a primary coil and a secondary coil are wound, and the current flowing through the primary coil is intermittently applied to the secondary coil. A voltage is generated to ignite the mixture in the combustion chamber. As an example of such a prior art, a technique described in Japanese Patent Application Laid-Open No. 58-54618 can be mentioned. In the case of this prior art, an ignition coil having a closed magnetic circuit type core is disclosed.

(Problems to be Solved by the Invention) In an ignition coil, the magnetic energy w that the core can store per unit volume is generally (magnetic permeability μ =
When constant), Specifically, it is determined by the saturation magnetic flux density determined by the volume of the core and the material of the core. Thus, the ignition coil is also expected to be reduced in size and weight for reasons such as the layout at the time of mounting on a vehicle. For this purpose, in the conventional case, a material having the highest possible saturation point is mainly selected as a core material. Such a core material is relatively expensive and has relatively poor workability, resulting in inconvenience such as an increase in cost. Therefore, it has been difficult to sufficiently reduce the size and weight of the ignition coil.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a method of manufacturing an ignition coil capable of reducing the volume of a core and reducing the size and weight, and which is excellent in productivity. It is an object of the present invention to provide a method for producing the same.

(Means and Actions for Solving the Problems) In order to achieve the above object, the present invention provides a method of closing a magnet by inserting a permanent magnet into a core that can be divided into a plurality of core pieces wound with a primary coil and a secondary coil. A method for producing a magnetic flux in a direction opposite to a magnetic flux generated when the primary coil is energized, the permanent magnet being permanently attached to the smallest core piece of the plurality of core pieces. A structure in which a magnetizable magnetic material is fixed to produce an integrated body, then a plurality of the bodies are simultaneously magnetized via a magnetizer, and then the magnetized body is assembled to the core body. did.

In other words, the present inventors sought various ways to reduce the size and weight of the ignition coil, and found that when a permanent magnet was inserted into the core and the primary coil was energized to generate a magnetic flux, the magnetic flux was generated in the opposite direction. Has increased the porcelain energy that can be extracted from the core. That is, it has been found that by generating a magnetic flux in the opposite direction even in a core having the same cross-sectional area, the same material, and the same winding specification, the magnetic energy that can be extracted from the core increases as compared with the case where it is not possible. It has been found that this makes it possible to reduce the sectional area of the core and reduce the size and weight of the ignition coil itself. Therefore, in the present invention, when manufacturing such an ignition coil, a permanent magnetizable magnetic material is fixed to the smallest core piece among the plurality of core pieces to produce an integrated body, and then the magnetizer is manufactured. , A plurality of combined bodies are simultaneously magnetized via the core, and then the magnetized combined body is assembled to the core body, so that the permanent magnet is not handled as a single unit at the time of assembling, so that the productivity is improved. Further, a plurality of combined bodies can be magnetized at the same time, which also improves productivity.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
For convenience, an ignition coil manufactured by the manufacturing method according to the present invention will be described first with reference to FIG. 2. As shown in the drawing, this ignition coil is a flat square closed magnetic circuit type formed by laminating silicon steel plates and the like. The core 10 includes a center core 10a and a side core 10b formed integrally therewith.
And a plug-in core 10c can be fitted to the open end thereof. Thus, the center core 1
A bobbin 12 is provided on the outer periphery of 0a, and a primary coil 14 having an appropriate number of turns is wound on the bobbin 12, as is well known. A second bobbin provided with a comb-shaped protrusion outside the primary coil 14;
The secondary coil 18 is similarly wound appropriately on the coil 16 (the number of coils 14 and 18 is simplified for convenience of illustration). The primary coil 14 is connected to a terminal 19 (FIG. 11), and the output of the secondary coil 18 is taken out via a second terminal (not shown). A case 20 is mounted outside the secondary coil 18 to protect the coils 14 and 18 from the outside, and an explosion-proof / insulating resin 22 is provided in a gap between the case 20 and the bobbin or coil. Will be filled. Note that ears 28 are formed at appropriate positions of the core main body 10a, and mounting holes 30 are formed therein.

The feature of the ignition coil manufactured by the manufacturing method according to the present invention in the above configuration is that the permanent magnet 32 is inserted into the air gap portion 26 formed between the side core 10b and the insertion core 10c. This will be described with reference to FIGS. 1 and 3. The main body and the insertion core 10c will be described.
A power supply voltage is supplied from a battery 40 to a primary coil 14 wound on a core 10 which can be divided into a plurality of parts by an ignition key (not shown), and the supplied current is supplied to a contact point or an igniter (both not shown). ), A high voltage is generated in the secondary coil 18 and the discharge unit 44 sparks.
The configuration up to this point is not different from the prior art. Thus, in the coil manufactured by the method according to the present invention, the core 10
In this case, the permanent magnet 32 is interposed between the magnetic flux Φm and the magnetic flux Φm in the direction opposite to the direction of generation of the magnetic flux Φc of the primary coil generated by the connection of the switch 42 (shown by reference numeral A in FIG. 1). Is formed. That is, as shown in FIG. 3, when the conventional core uses only the magnetic flux Φc in the plus direction as shown by the broken line,
In the coil manufactured by the method according to the present invention, the core 10 receives the magnetic flux −Φm in the minus direction and generates the magnetic flux Φc in the plus direction as shown by the one-dot chain line. As a result, as shown by the solid line, Φc− ( −Φm) = Φc + Φm, and the amount of change in the magnetic flux increases by Φm compared to the conventional example. Regarding the reason why the output is improved by generating the magnetic flux in the opposite direction, the fourth is
Referring to the figures, the figures are actually measured data (in the figure, Mg represents a permanent magnet). As is clear from this figure, the permeance in a practical use range where the magnetic field strength H is large, that is, the ampere turn AT is large. This is because P does not decrease. That is, the magnetic energy w is different from the above equation. (L: inductance, I: current when the magnetic permeability μ = constant), it can be seen from this equation that the magnetic energy w increases with an increase in the inductance L. The inductance L is represented by L = μSN ² / l [H] (2) (μ: magnetic permeability, S: sectional area, N: number of turns, l: magnetic path length). Further, since the permeance P is P = μS / l (3), the inductance L is L = PN ² [H] (4) from the equations (2) and (3), and the magnetic energy w becomes It can be seen that it increases in proportion to the permeance P. That is, as shown in FIG. 4, by generating the magnetic flux Φm in the reverse direction, the permeance does not become small in the actual use range, so that a large magnetic energy can be obtained. Equations (1) and (2)
From (3), if the magnetic energy w is μ = constant, w = μSN ² I ² / 2l [J] (5) can be rewritten. If the magnetic permeability μ is an increment magnetic permeability (μ = ΔB / ΔH), the magnetic permeability μ is BH
Since the BH curve is determined by the slope of the curve, if the BH curve does not enter the saturation region, that is, if μ = constant, the magnetic energy w increases in proportion to the square of the current I, The output can be improved.

Subsequently, an embodiment of the ignition coil manufactured by the method according to the present invention will be described.

First, the conversion efficiency of magnetic energy of a 10 × 10 mm core (made of silicon steel plate) to a spark plug was calculated from FIG. In this case, the magnetic energy of the magnetized core is , And the hatched portion in FIG. In this case, the core dimensions were magnetic energy ignition energy efficiency 10 × 10 mm 47.6 mJ 32.0 mJ 67%.

Subsequently, the cross-sectional area and shape of the core were determined. That is, the sixth
As shown in the figure, as a result of conducting an experiment before and after inserting permanent magnets into cores of various sizes, permanent magnets (10 x 10 x 2 mm thick) were used for the same winding specification.
Since core area S Using it can be reduced by about 40% was found to, S = 8 × as 60% of 10 × 10 = 100mm ²
8 was determined to be 64 mm ² .

Next, the magnetic energy of a core of this size when no permanent magnet was inserted was calculated from FIG.
It was 34.4 mJ.

Next, the permeance coefficient was calculated from the following equation by the provisional magnetic path method.

Permeance coefficient ∝S / l ≒ 5.3 Next, the magnetic energy Δw of the core to be increased by interposing the permanent magnet was calculated from the above.

Δw = 47.6−34.4 = 13.2 mJ From FIG. 8, the increase ΔB of the magnetic flux density B is ΔB = 0.23 [T].

Next, based on the experimental data shown in FIGS. 8 (a) to (d) and FIG. 6, the size of the permanent magnet was changed to 7 × 8 × 2 mm in thickness.
It was tentatively decided. The permanent magnet material is a samarium / cobalt magnet CORMAX-2300 (Sumitomo Special Metals,
Product name).

Next, the operating point of this permanent magnet was confirmed. The condition under which the permanent magnet operates stably is as shown in FIG. 9: Hc-worst> Hd + Hi (6). In this case, Hc: coercive force Hc-worst: worst value of coercive force Hc in consideration of ambient temperature, conditions, manufacturing variations, etc. Hd: self-demagnetizing field Hi: magnetic field generated in the magnet by the coil, Hi = k · AT / lg
(AT: magnetomotive force (ampere turn), k: magnetomotive force loss coefficient, l
g: gap length) As a result, the values calculated from FIG. 9 are Hd = 1.6K0e, Hi
= 3.9K0e, Hc-worst = 8.8K0e (temperature 140 ° C, catalog value). Therefore, from equation (6), 8.8> 1.6 + 3.9, which was judged to be satisfactory. Also, it was confirmed from FIG. 9 that the magnetic energy increased by ΔB = 0.4 [T], and the increase was as follows: w = (ΔB ′ / ΔB) · Δw = 0.4 / 0.23 × 13.2 = 23.0 mJ, and the total magnetic energy was 34.4 + 23.0 = 57.4 mJ, so it could be judged to be satisfactory.

The results of the experiment described above are summarized in FIG. 10, and the measured values are as follows.

As described above, the values obtained through the experiment also show that the magnetic energy and the ignition energy are significantly increased by the insertion of the permanent magnet, and are increased by 50% in the experimental example.
Accordingly, the core size can be reduced, and the size of the ignition coil itself can be reduced in size and weight, so that the layout at the time of mounting on a vehicle is facilitated, and further, there is an advantage that costs such as material costs are reduced. Incidentally, in the above, as shown in FIG. 9, the permanent magnet is Hc (preferably Hc-wors) at the operating temperature.
t) Use within the range of> Hd + Hi, and use it as long as the permanent magnet is not destroyed by the magnetic field Hi due to the primary coil. From that point, as described above, Hc
Rare earth / iron magnets, such as samarium / cobalt magnets, are preferred. Further, the permanent magnet inserted into the air gap portion has a significantly lower magnetic permeability than the material of the core (silicon steel plate or the like), so that it can function not only as a magnetic flux generating means but also as an original air gap means. It goes without saying that you can do it.

Thus, the feature of the present invention is that the ignition coil is configured to be manufactured efficiently. This point will be described with reference to FIGS. 11 (a) to 11 (d). First, as shown in FIG. 1 (a), when the insertion core 10c is not fitted, the center part 10a of the core body is separately manufactured and the coil part accommodated in the coil case 20 is mounted. Thus, as shown in FIG. 2B, a magnet material 320 made of a magnetic material (hard material) that can be permanently magnetized is fixed to the insertion core 10c of the core via an appropriate means such as bonding in the process before and after the process. Then, the combined body 100 made of the insertion core and the magnet material is manufactured. Next, as shown in FIG. 1C, a plurality of the coupling bodies 100 are put together and the magnetizing yoke 1
02, a large current is passed for a short time through a magnetizing power supply (not shown) to permanently magnetize the magnet material 320,
Make 2 Finally, as shown in FIG. 5 (d), the assembly is completed when the combined body 100 including the insertion core and the permanent magnet is fitted to the core body where the coil has been mounted.

In the above manufacturing process, the permanent magnet is fixed to one of the core pieces forming the magnetic path in an unmagnetized state and magnetized in that state, so the permanent magnet magnetized when assembled to the core main body portion Does not need to be handled alone, thereby improving productivity. In other words, permanent magnets are difficult to manage on the production line because they are easily attracted to nearby iron materials or attract iron powder in the magnetized state, especially when the size of permanent magnets is small. Is remarkable, but if it is already fixed separately at the time of magnetization as described above, handling becomes easy and production efficiency is improved. Thus, in the above-mentioned manufacturing process, in order to fix the magnetic material, the core piece having the shortest magnetization direction (the insertion core) is used.
10c) is selected and fixed to it. That is, as shown in FIGS. 12 (a) and 12 (b),
Although there are various methods such as a splitting method and a three-segmenting method, in the present invention, the permanent magnet is always replaced with a core piece having the shortest magnetization direction (in FIG. 12 (a), the insertion core 10c, and in FIG. Is fixed to the center core 10a), so that the number of coupling bodies that can be accommodated in the magnetizer when magnetizing can be increased, the magnetizing power can be reduced, and the productivity can be reduced. It can be improved.

(Effects of the Invention) The present invention provides a closed magnetic circuit core by inserting a permanent magnet into a core that can be divided into a plurality of core pieces around which a primary coil and a secondary coil are wound, and when the primary coil is energized. In a method of manufacturing an ignition coil configured to generate a magnetic flux in a direction opposite to a magnetic flux generated thereby, a magnetic material capable of being permanently magnetized is fixed to a smallest core piece of the plurality of core pieces to form an integrated body. And then simultaneously magnetizing a plurality of coupling bodies via a magnetizer, and then assembling the magnetized coupling bodies to the core body, so that only the reverse magnetic flux is taken out of the core. Increased magnetic energy that can be used to reduce the cross-sectional area of the core and produce a small and lightweight ignition coil, eliminating the need to handle a permanent magnet alone, thus improving productivity It has the advantage that it can be done. Further, since the magnetic material is fixed to the smallest core piece and integrally joined, and a plurality of magnets are simultaneously magnetized via the magnetizer, the number of joined bodies that can be accommodated in the magnetizer can be increased. Thus, productivity can be further improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an ignition coil manufactured by the manufacturing method according to the present invention, FIG. 2 is an explanatory longitudinal sectional view showing a more detailed configuration of the ignition coil of FIG. 1, and FIG. FIG. 4 is a BH curve diagram for explaining the increase in magnetic energy of the ignition coil, FIG. 4 is a permeance-AT characteristic diagram for explaining the reason, and FIG. -H curve diagram, Fig. 6 shows previous experimental data on magnetic properties of cores of various sizes with and without permanent magnets interposed, and Fig. 7 shows BH curves used in the experimental examples. FIGS. 8 (a) to 8 (d) are explanatory diagrams showing the relationship between the thickness of the permanent magnet used in the experimental example and the permeance coefficient, etc. FIG. 9 is a demagnetization curve of the permanent magnet used in the experimental example FIG. 10 shows BH showing the measurement results of the experimental example. FIGS. 11 (a) to 11 (d) are explanatory views showing an embodiment of a method of manufacturing an ignition coil according to the present invention, and FIGS. 12 (a) and 12 (b) show features of the manufacturing method according to the present invention. FIG. 10 cores (10a center core, 10b side cores,
10c: Insert core), 12, 16: Bobbin, 14: Primary coil, 18: Secondary coil, 26: Air gap, 32:
Permanent magnet, 100 ... combined body, 102 ... magnetized yoke, 320 ...
… Magnetic material (magnet material)

Claims (1)

(57) [Claims] 1. A closed magnetic circuit core in which a permanent magnet is inserted into a core that can be divided into a plurality of core pieces around which a primary coil and a secondary coil are wound, and a magnetic flux generated by energizing the primary coil. A method of manufacturing an ignition coil configured to generate a magnetic flux in a direction opposite to the direction described above, comprising the steps of: a. Fixing a permanent magnetizable magnetic material to a smallest core piece of the plurality of core pieces to produce an integrated body; B. Then, a plurality of combined bodies are simultaneously magnetized via a magnetizer; and c. Then, the magnetized combined bodies are assembled to a core body.