JPH01287907A - Closed magnetic circuit coil, manufacture thereof and the same coil built-in distributor - Google Patents

Abstract

PURPOSE:To make it possible to obtain excellent thermal conductivity and heat radiating property with a simple structure by a method wherein the Joule heat generated on the main coil is transmitted to the cylindrical circumferential core of a closed magnetic circuit core, and the transmitted heat is dissipated to the outside air from the external surface of the circumferential core. CONSTITUTION:A closed magnetic circuit coil 1 consists of the primary coil 13 and a secondary coil 14 wound on a closed magnetic circuit core 11, and a circumferential core 11a and a center core 11b are integrally formed on the closed magnetic circuit core 11. When a flux change is generated on the closed magnetic circuit core 1 by the intermission of the primary current applied to the primary coil 13, high voltage is induced on the secondary coil 14. At this time, as Joule heat is generated on the primary coil 13 by the application of a secondary current, the heat is transmitted to a core 11c and the circumferential core 11a of a cylindrical body from the center core 11b, and it is dissipated to the outside air from the large surface area of the external surface. As a result, an excellent heat conductivity can be obtained, a large heat radiating area can be secured, and heat is dissipated excellently.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a closed magnetic circuit coil in which a primary coil and a secondary coil are wound around a closed magnetic circuit core, and in particular to a closed magnetic circuit coil suitable for an ignition coil of an internal combustion engine, and its method. Regarding the manufacturing method. together,
This invention relates to a power distribution device for an internal combustion engine that incorporates this closed magnetic circuit coil.

[Prior Art] As is well known, a closed magnetic circuit coil is one in which a primary coil and a secondary coil are wound around an iron core or core such that a magnetic flux path forms a closed circuit. This is contrasted with an open magnetic path coil,
It has various advantages such as low leakage magnetic flux and high energy conversion efficiency.

Therefore, it is utilized as a small, lightweight, high-performance ignition coil in internal combustion engines. In particular, in order to meet the recent demands for smaller, lighter, and space-saving parts installed in internal combustion engines,
The ignition coil is housed in the power distributor, and a closed magnetic circuit coil is utilized for this.

The general structure of a closed magnetic circuit coil used as an ignition coil is that a pair of E-shaped laminated cores of silicon steel plates are joined facing each other to form a Japanese-shaped closed magnetic circuit core, and a primary coil is wound around the central core. A secondary coil is wound around the outer circumference of the coil. A resin-molded closed magnetic circuit coil is known in which the primary coil and the secondary coil are filled with a thermosetting resin and cured by heating. Note that the closed magnetic circuit core is usually provided with a minute air gap, that is, an air gap, in the central core portion so that the hysteresis of the magnetic flux does not become large.

It also has a cylindrical central leg through which the drive shaft of the power distributor, that is, a shaft that rotates in synchronization with the rotation of the internal combustion engine, is inserted. It has an extending arm and a similar arm that is magnetically coupled to the other end in the axial direction, and has an iron core that magnetically couples these arms at the outer leg, and has an iron core that is attached to the central leg. A known technique is to form a closed magnetic circuit coil by winding a secondary coil around a primary coil and its outer periphery, and to incorporate the coil into a power distributor.

This is disclosed in Japanese Utility Model Application Publication No. 81-181877, and according to this, the space around the shaft of the power distributor can be effectively utilized. In this publication, in order to prevent noise from being generated in the magnetic pickup due to leakage magnetic flux when an air gap is formed in the central leg, an air gap is provided in the outer leg of the iron core.

[Problem to be solved by the invention] However, since the conventional closed magnetic circuit coil with a laminated steel plate core has a small heat transfer path area and low thermal conductivity, it is necessary to take measures against the temperature rise of the coil, especially when it is built into a power distribution device. This increases the number of design constraints.

In addition, in the closed magnetic circuit coil described in the above publication, the heat is radiated through the arms and outer legs extending in all directions and the case in contact with these, so the heat radiating area is small, and the heat radiating area is small. Problems with sexuality remain. Moreover, since the closed magnetic circuit core is divided into four parts: a central leg, two legs, and an outer leg, the number of parts increases, which reduces ease of assembly and increases costs.

Therefore, an object of the present invention is to provide a closed magnetic circuit coil having a simple structure and good thermal conductivity and heat dissipation.

Another object of the present invention is to provide a simple method for manufacturing the above-mentioned closed magnetic circuit coil.

Another object of the present invention is to install the closed magnetic circuit coil in a power distributor, prevent the closed magnetic circuit coil from becoming high temperature through appropriate heat radiation, and ensure its function as an ignition coil.

[Means for Solving the Problem] In order to achieve the above object, the closed magnetic circuit coil of the present invention has the following features:
A closed magnetic body comprising a peripheral core of a cylindrical body, a central core extending in the axial direction of a central portion of the peripheral core, and an end core that magnetically couples the central core and the peripheral core to form a closed magnetic path. The closed magnetic circuit core includes a primary coil and a secondary coil wound around the central core of the closed magnetic circuit core.

The closed magnetic circuit coil includes a peripheral core of a bottomed cylindrical body, a central core of the cylindrical body extending in the axial direction from the bottom surface of the peripheral core toward the open end and having a through hole in the axial direction, and an end of the central core. a closed magnetic path core of a magnetic material forming a closed magnetic path and comprising an end face core of a lid that magnetically couples the opening end of the peripheral core to the opening end of the peripheral core;
a primary coil wound around the central core of the closed magnetic circuit core;
It is preferable to include a secondary coil wound around the primary coil.

In the above-mentioned closed magnetic circuit coil, a closed magnetic circuit core is formed of magnetic aluminum obtained by mixing aluminum powder and iron powder and then press-forming, and the primary coil and secondary coil are formed in a space defined by the closed magnetic circuit core. It is preferable that the gap formed between the coil and the coil is filled with synthetic resin.

Alternatively, in the closed magnetic circuit coil, a synthetic resin and iron powder are mixed and then heated and hardened to form a closed magnetic circuit core, and between the primary coil and the secondary coil within the space defined by the closed magnetic circuit core. It is preferable to fill the voids formed with synthetic resin.

Furthermore, radiation fins may be formed on the outer peripheral surface of the cylindrical body of the peripheral core in the closed magnetic circuit coil.

The closed magnetic circuit coil includes a cylindrical primary bobbin around which a primary coil is wound and which has a through hole in the axial direction, and a through hole in the axial direction that accommodates the primary bobbin, around which the secondary coil is wound. and a secondary bobbin having a cylindrical body, and a through hole of the primary bobbin is fitted into the central core so that the primary bobbin and the secondary bobbin can be housed in the peripheral core.

In manufacturing the closed magnetic circuit coil of the present invention, magnetic aluminum, which is formed by mixing aluminum powder and iron powder and then being press-formed, is cold-forged into the peripheral core of the bottomed cylinder and from the bottom surface of the peripheral core to the open end. A central core of a cylindrical body extending in the axial direction and having a through hole in the axial direction is formed, and a primary coil and a secondary coil wound in a cylindrical shape are inserted into the central core. A preferred method is to fill the gap with a thermosetting resin and attach an end core of a lid body to the open end of the peripheral core to magnetically couple the end of the central core to the open end of the peripheral core.

The power distributor with a built-in closed magnetic circuit coil of the present invention has a closed magnetic circuit coil equipped with a peripheral core of the bottomed cylindrical body, and a shaft rotating in synchronization with an internal combustion engine is inserted into the through hole of the central core to close the magnetic circuit. The coil is housed within the housing.

Further, in the power distributor with a built-in closed magnetic circuit coil, the housing includes a cap that is a cylindrical body with a bottom, an open end that is joined to the open end of the cap, and an insertion hole that supports the shaft at the bottom. and a housing main body, at least a cylindrical portion of the housing main body is configured with the peripheral core, and the shaft can be configured to be inserted into and supported by a through hole of the central core.

Conversely, the cylindrical body portion of the cap may be formed of the peripheral core, and the shaft may be inserted into a through hole of the central core and supported.

Furthermore, radiation fins may be formed on the outer peripheral surface of the peripheral core that constitutes the housing body of the power distributor with a built-in closed magnetic circuit coil.

[Operation] In the closed magnetic circuit coil configured as described above, when a magnetic flux change occurs in the closed magnetic circuit core due to intermittent primary current supplied to the primary coil, a high voltage is induced in the secondary coil. At this time, Joule heat is generated in the primary coil due to the primary current being passed through the primary coil, which is transmitted from the center core to the end core and the peripheral core of the cylindrical body, and is radiated to the outside air from the outer surface having a large surface area.

And, in the power distributor having the above-mentioned closed magnetic circuit coil,
Due to the same action as described above, the closed magnetic circuit coil effectively functions as an ignition coil, and the generated predetermined high voltage is distributed to each cylinder of the internal combustion engine in accordance with the rotation of the shaft. Heat generated by energizing the primary coil is radiated to the outside air from the outer surface of the peripheral core.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the closed magnetic circuit coil of the present invention. The closed magnetic circuit coil 1 is formed by winding a primary coil 13 and a secondary coil 14 around a closed magnetic circuit core 11. FIG. The closed magnetic circuit core 11 is integrally formed with a peripheral core lla of a bottomed cylindrical body and a central core itb of a hollow cylindrical body extending in the axial direction from the bottom surface toward the open end. An end core tic of the annular lid that magnetically couples the peripheral core 11a and the central core llb is placed on the open end of the peripheral core lla and fixed in surface contact. Closed magnetic circuit core 11
The outer surface of is surrounded by a case 12 made of synthetic resin.

The closed magnetic circuit core 11 is formed by cold forging or cutting a block of magnetic material, commonly known as magnetic aluminum, which is formed by mixing aluminum powder and iron powder and then press-molding the mixture in a mold. Note that the iron powder to be mixed with the aluminum powder includes not only powder but also fibrous so-called iron fibers. Alternatively, the closed magnetic circuit core 11 may be formed by mixing this iron powder with a synthetic resin and then heating and curing the mixture.

Then, the central core Ilb is inserted into the hollow part of the primary bobbin 15 of the synthetic resin cylinder around which the primary coil 13 is wound, and the synthetic resin cylinder around which the secondary coil 14 is wound. A secondary bobbin 16 is fitted into the primary bobbin 15. The primary film 13 has a large diameter copper wire, and the secondary coil 1
4 is wound with a small-diameter copper wire, and the number of windings of both coils is set according to the desired output voltage to be induced in the secondary coil 14 when a predetermined temporary current is passed through the primary coil 13. Ru. The primary coil 13 and the secondary coil 14 are connected to an external circuit or the like via a lead wire (not shown) inserted through a hole (not shown) provided in the end face core lie of the lid.

A gap exists between the primary coil 13 and the primary bobbin 15 and the secondary coil 14 and the secondary bobbin 16, and a gap also exists between these and the closed magnetic circuit core 11. These voids are then filled with a thermosetting synthetic resin and cured to form the resin portion 17. Thereby, the primary coil 13 and the secondary coil 14 are impregnated and fixed, and the insulation that can withstand the high voltage output from the secondary coil 14 is ensured. In the closed magnetic circuit core 11, a small air gap, ie, an air gap lid, is formed in an annular shape between the center core ttb and the end core 11c so that the change in effective magnetic flux becomes large.

Further, the central core fib defines a through hole lie passing through in the axial direction.

In manufacturing the closed magnetic circuit coil 1 having the above configuration, the closed magnetic circuit core 11 is first formed by cold forging the magnetic aluminum described above. Next, the primary bobbin 15 around which the primary coil 13 is wound and the secondary bobbin 16 around which the secondary coil 14 is wound are assembled as one body, and the magnets are closed so that the center core flb is inserted into the hollow part of the primary bobbin 15. It is inserted into the channel core 11. Then, after filling the gap in the closed magnetic circuit core 11 with a thermosetting synthetic resin to form the resin part 17, the end face core llc is attached to the open end of the closed magnetic circuit core 11 in close contact.

Note that various joining methods such as fitting, adhesion, and screwing can be used, but it is necessary that the two be effectively coupled magnetically.

In the above embodiment, the closed magnetic circuit core 11 is the peripheral core ll
a is a cylinder with a bottom, and the central core Ilb is integrally formed so as to extend from the bottom surface of the cylinder.
It may also be joined to a.

To explain the operation of the closed magnetic circuit coil 1 having the above configuration,
The intermittent primary current supplied to the primary coil 13 causes a magnetic flux change in the closed magnetic circuit core 11 . This magnetic flux change is larger than that of an open magnetic path core, and therefore the energy conversion efficiency is also large. Furthermore, the presence of the air gap lid makes it possible to ensure effective changes in magnetic flux with suppressed hysteresis. As a result, a predetermined high voltage is generated in the secondary coil 14 and output via a lead wire (not shown).

In this case, Joule heat is generated in the primary coil 13 due to the supply of the primary current, but such heat must be quickly removed in order for the closed magnetic circuit coil 1 to function effectively. In this embodiment, the heat generated in the primary coil 13 is transferred to the closed magnetic circuit core 11, but since the closed magnetic circuit core 11 is a hollow cylinder with a large surface area, it is efficiently transmitted from the outer surface of the closed magnetic circuit core 11 to the closed magnetic circuit core 11. Dissipated. Moreover, the closed magnetic circuit core 11 has a large heat transfer passage cross-sectional area and excellent thermal conductivity, and is made of magnetic aluminum, a material with good thermal conductivity. That is, while the thermal conductivity of conventional core forming steel plates is 0.18 cal/cm .degree. C..sec, it is 50 vol/cm. The thermal conductivity of magnetic aluminum mixed with % iron powder is 0,36 cal/ca+ ・'C・se
c, which is twice the value, and good thermal conductivity can be obtained.

Next, an embodiment will be described in which the closed magnetic circuit coil shown in FIGS. 1 and 2 is built into a power distributor as an ignition coil. The power distribution device shown in FIG. 3 has a housing composed of a housing body 2 made of an aluminum alloy cylinder and a cap 3 made of a synthetic resin cylinder detachably joined to the housing body 2. The power distribution unit is mainly located within the cap 3. 50 is formed, and the signal generator 30 is housed in the housing main body 2, and the centrifugal advance mechanism 20 and the negative pressure advance mechanism 40 are also provided.

Furthermore, an ignition coil 10 constituted by the closed magnetic circuit coil 1 shown in FIGS. 1 and 2 is housed in the housing body 2, and an ignition circuit unit, commonly called an igniter 70, which connects and connects the primary current of this ignition coil 10 is housed in the housing body 2. It is housed within the cap 3.

A bearing 5 is provided in an insertion hole formed in the housing body 2, and a drive shaft 4, which is a shaft in the present invention, is inserted through the bearing 5 and supported. A gear (not shown) is fixed to one end of the drive shaft 4 and meshes with a gear formed on a camshaft (not shown) in the internal combustion engine, so that the drive shaft 4 rotates in synchronization with the camshaft. It is composed of The other end of the drive shaft 4 passes through the hollow part of the ignition coil 10, and a cylindrical rotor shaft 31 is rotatably fitted to the tip thereof, and both are connected via a centrifugal advance mechanism 20. . The drive shaft 4 is rotatably fitted into a bearing plate 35 having a cylindrical bearing portion formed in the center, and the bearing plate 35 is fixed to the housing body 2 with a screw.

The ignition coil 10 has the same structure as shown in FIGS. 1 and 2, and the same reference numerals indicate the same parts. As is clear from FIG. 3, the hollow part of the closed magnetic circuit core 11, that is, the central core ll
The drive shaft 4 is rotatably inserted through the axial through hole 11e of b, and the ignition coil 10
Direction in the direction of the power distribution unit 50 is restricted.

The centrifugal advance mechanism 20 rotates the rotor shaft 31 relative to the drive shaft 4 to advance the angle by utilizing the fact that the governor weight 21 is displaced in the radial direction by centrifugal force in accordance with the rotation of the internal combustion engine. This is a mechanism for obtaining this, and has a well-known configuration. That is, a cam-shaped governor weight 21 is rotatably attached to a governor plate 22 fitted and fixed to the drive shaft 4 by a weight support bin 23, and as the drive shaft 4 rotates, centrifugal force acts on the governor weight 21. The outer end expands outward. On the other hand, a drive plate 24 is fitted and fixed to the rotor shaft 31, one end of a governor spring 26 is locked to a spring hanger pin 25 planted on the drive plate 24, and the other end is fixed to a weight support pin 23. It is locked. Therefore, the cam surface of the governor weight 21 comes into contact with the side end of the drive plate 24, and the outer end of the governor weight 21 is rotated by centrifugal force against the tension of the governor spring 26 as the rotational speed of the drive shaft 4 increases. The cam surface expands outward, and the drive plate 24 is driven by the movement of the cam surface. As the governor weight 21 expands, the rotor shaft 31 rotates in the rotational direction of the drive shaft 4 relative to the drive shaft 4. That is, the angle is advanced by the rotation angle of the rotor shaft 31.

The signal generator 30 includes a signal plate 24a integrally formed on the peripheral edge of the drive plate 24 fitted to the rotor shaft 31, and a magnetically sensitive sensor 33 disposed opposite to the signal plate 24a. A support plate 34 having a support plate 33 mounted thereon is rotatably fitted to a bearing plate 35 via a bearing member. Signal plate 24
a is a ferromagnetic disk whose outer periphery is provided with a number of notches corresponding to the number of cylinders of the internal combustion engine, for example, four; in this embodiment, it is formed integrally with the drive plate 24; It may be formed separately and fitted. The rotor shaft 31 is a substantially cylindrical body made of iron-based metal material, and the drive plate 24 is fitted around the outer periphery of one end, and the power distribution rotor is fitted to the other end.

The magnetic sensor 33 has a signal plate 24a attached to a base 30a fixed to the peripheral edge of the support plate 34.
A slit 30c is formed to accommodate the. and,
Recesses are formed on both sides of the slit 30c, and a pair of cores 33a each having an oval-shaped cross section are disposed in each recess so that their end surfaces face each other. That is, a magnet 33m is embedded adjacent to one core of the magnetically sensitive sensor 33, a Hall element 33s is embedded adjacent to the other core, and the base 30 is embedded by insert resin molding or resin molding.
It is fixed integrally to a. The Hall element 33s has a lead wire (
(not shown) to the igniter 70. still,
A 6n air-sensitive sensor such as a magnetoresistive element or an optical sensor may be used in place of the Hall element 33s.

Therefore, when the drive plate 24 rotates due to the rotation of the rotor shaft 31, the signal plate 24a moves through the slit 3.
Move within 0c. In this case, when the plate surface portion of the signal plate 24a exists between the pair of cores 33a, a magnetic path is formed in which the magnetic flux flowing out from the magnet 33m flows into the magnet 33m via the core 33a and the signal plate 24a. , the Hall element 33s is magnetically shielded and the voltage output is small. On the other hand, when the notch of the signal plate 24a is located between the pair of cores 33a, part of the magnetic flux of the magnet 33m is given to the Hall element 33s, and a large voltage output is obtained due to the Hall effect.

Thus, the pulse signal is transmitted to the igniter 70 via the lead wire.
is output to.

A bottle 34a is installed on the outer periphery of the support plate 34, and one end of a rod 41 is rotatably attached to the bottle 34a. The other end of the rod 41 is connected to a diaphragm device 42, forming a well-known negative pressure advance mechanism 40. That is, the diaphragm chamber of the diaphragm device 42 is connected to the intake pipe (not shown) of the internal combustion engine, the rod 41 is driven according to the intake pipe negative pressure, and the support plate 34 is rotated in the opposite direction to the rotation of the drive shaft 4. move. As a result, the support plate 34 is advanced by the rotational angle of the drive shaft 4.

A lid body 2a is fixed to the housing body 2, and this lid body 2
The igniter 70 is placed and fixed on the cap 3.
is housed within. The igniter 70 is the ignition coil 10
The primary coil 13 is connected to the primary coil 13, and the primary current is interrupted in response to the pulse signal.

A power distribution rotor 51 is fitted into the tip of the rotor shaft 31 and is fixed to rotate together with the rotor shaft 31, and a rotor electrode 51a is fixed to the top surface of the power distribution rotor 51. The discharge portion at the tip of the rotor electrode 51a is connected to a side electrode 52 provided around the cap 3.
It is arranged to face the. The center electrode 53 is formed by a spring biasing the carbon brush 53a to press the sliding contact portion of the rotor electrode 51a.

Then, it is connected to the secondary coil 14 of the ignition coil 10 via the connection electrode 53c and the connection electrode 2c provided on the housing body 2 side. In addition, the connection electrodes 53c and 20
As is clear from FIG. 3, the connection structure between the caps 3 and 3 is such that it can be disconnected in response to the attachment and detachment of the cap 3, and is connected via a spring.

The operation of the embodiment configured as above will be explained. When the drive shaft 4 rotates in a predetermined direction in synchronization with the rotation of the internal combustion engine, rotational force is transmitted to the drive plate 24 and the rotor shaft 31 via the centrifugal advance mechanism 20, and the signal plate 24a rotates in the same direction. At this time, the centrifugal advance mechanism 20
According to the rotation of the internal combustion engine, the signal plate 24a
rotates in the direction of rotation with respect to the drive shaft 4 to advance the angle.

On the other hand, in the magnetic sensor 33, the support plate 34 rotates around the drive shaft 4 by the negative pressure advance mechanism 40.
The angle is advanced according to the negative pressure in the intake pipe of the internal combustion engine. Therefore, each of the signal plates 24a and 61 gas-sensitive sensor 33 is advanced in accordance with the operating state of the internal combustion engine, and the signal plate 24a is moved between the cores 33a of the magnetic sensor 33.
moves. In response, the Hall element 33s outputs a pulse signal with a pulse width corresponding to the speed of passage through the notch of the signal plate 24a. An ignition signal is output from the igniter 70 in response to this pulse signal, the primary current of the ignition coil 10 is interrupted in response to the ignition signal, and a high voltage is induced in the secondary coil 14. When this high voltage is applied from the center electrode 53 to the sliding contact portion of the rotor electrode 51a, the rotor electrode 51a
A spark discharge occurs in the gap between the discharge portion 1a and the side electrode 52, and is transmitted to the side electrode 52. And the power distribution rotor 51
each spark plug (not shown) in a predetermined order as the
Power is distributed to

In the above, when the primary current is supplied to the ignition coil 10 and Joule heat is generated, most of the Joule heat is generated by the primary bobbin 15, the resin part 17, the central core 11b, as shown by the broken line in FIG.
It is transmitted to the bottom of the first end core 1ic and the peripheral core lla, and is radiated to the outside air from the outer peripheral surface of the peripheral core lla via the case 12 and the housing body 2. In particular, the presence of the closed magnetic circuit core 11 having a high thermal conductivity and a cylindrical peripheral core Ila provides good thermal conductivity and heat dissipation, and ensures stable function of the ignition coil 10.

4 and 5 show another embodiment of the power distributor of the present invention, and the same parts as those of the power distributor shown in FIG. 3 are given the same reference numerals. In the embodiment shown in FIG. 3, the closed magnetic circuit core 11 is surrounded by a case 12 and housed in the housing body 2, whereas in this embodiment, the case 12 is not provided and the peripheral core lla of the closed magnetic circuit core 11 is housing body 2
The cylindrical body portion of the

In FIG. 4, a peripheral core 110 of a closed magnetic circuit coil 100
A constitutes the housing main body 200 of the power distributor shown in FIG. 5, and the end face core 11C is fitted into a stepped portion formed on the peripheral core 110a. In this embodiment, a non-magnetic annular member 11g is provided in the air gap corresponding to the air gap 11d shown in FIG. 3, but the rest of the structure is the same as that shown in FIG. 3, so the explanation will be omitted. do.

Then, as shown in FIG. 5, the signal generator 30 and the like are installed in the peripheral core 110a of the closed magnetic circuit coil 100 that functions as an ignition coil, and the support member 201 is fixed, similar to the embodiment shown in FIG. A power distribution device is configured. In this embodiment, the support member 201 that accommodates the bearing 5 and supports the drive shaft 4 is fixed to the peripheral core 110a to form the housing body 200, but the support member 201 is integrally formed with the peripheral core 110a. It may also be a thing.

The present embodiment operates in the same manner as the embodiment shown in FIG.
b, it is radiated to the outside air from the side surface of the peripheral core 110a and the bottom surface of the support member 201 via the end core tic and the bottom of the peripheral core 110a. That is, in the embodiment shown in FIG. 3, heat is radiated to the outside air through the case 12 and the housing body 2, whereas in this embodiment, the peripheral core 110 that constitutes the housing body 200 is radiated to the outside air through the case 12 and the housing body 2.
Since heat is radiated directly from a, even better heat dissipation performance can be obtained.

Incidentally, the peripheral core 110a in the above embodiment is also formed by cold forging or cutting the magnetic aluminum block described above, but instead of this, a synthetic resin is mixed with the aforementioned iron powder and then heated and hardened. You may use the one molded into the above shape by doing so.

FIG. 6 shows still another embodiment of the power distributor of the present invention, in which the housing main body 200 in the embodiment shown in FIGS. 4 and 5 is formed of a peripheral core, and a plurality of A housing main body 201 is constructed by forming a protrusion and providing a radiation fin 201a, and the rest of the construction is the same as the embodiment shown in FIGS. 4 and 5. The heat radiation fins 201a further improve heat radiation, and the closed magnetic circuit coil 100 efficiently radiates heat.

FIG. 7 shows another embodiment of the closed magnetic circuit coil of the present invention, and unlike the closed magnetic circuit core 11 of the embodiment shown in FIG. A core 111a and a central core 111b, which is a cylindrical body made of magnetic aluminum and which is separately joined to the center during assembly.
It is made up of. Flange portions 111C are provided at both ends of the center core 111b in the axial direction, and an epoxy resin is coated in the recess formed between the flanges 1110 to form an epoxy coating layer 1.
5a is formed. And this epoxy coating layer 1
The coil 13 is further wound around the central core 1ll.
b is joined to the bottom surface of the peripheral core 111a.

With this configuration, the primary coil 13 is connected to the center core 111 by the epoxy coating layer 15a, which is an insulating coating layer.
b, and the bobbin 15 of the embodiment shown in FIG. 1 is no longer necessary. Therefore, in the embodiment shown in FIG. 1, the distance between the primary coil 13 and the central core 111b is determined by the thickness of the bobbin 15 (0.6 to 1.2 a+m) and the distance between the primary bobbin 15 and the central core 11b. In this example, the thickness of the epoxy coating layer 15a (0.2 to 0.5 m + e
) only. Thereby, the thermal conductivity from the primary coil 13 to the central core 111b becomes even better.

As described above, in each of the embodiments, the peripheral core of the closed magnetic circuit coil disposed in the power distribution device is a cylinder, and the surface area of its outer peripheral surface is larger than that of the conventional laminated steel plate core, resulting in an excellent heat dissipation effect. Furthermore, since the heat transfer passage has a large cross-sectional area and is made of magnetic aluminum having high thermal conductivity, good thermal conductivity can be obtained.

Regarding this heat dissipation characteristic, in order to compare the prior art and each embodiment of the present invention, the temperature distribution according to the models of FIGS. 8(a) to (d) is shown, that is, in FIG. 8(a), (stomach)
8 shows a model of a power distributor having a conventional steel plate laminated core, 81 is a coil corresponding to a single-layer coil, 8
Reference numeral 2 indicates a resin corresponding to the bobbin, 83 a core corresponding to the laminated steel plate core, 84 a resin corresponding to the case, and 85 an aluminum alloy corresponding to the main body of the power distribution housing. FIG. 8(b)(a) shows the temperature distribution at each part when the end face of the aluminum alloy 85 on the opposite side is used as a heat dissipation surface. Similarly, (b) of FIG. 8(a) is a model corresponding to the embodiment of FIG. (d) A model corresponding to the embodiment shown in the figure, which is provided with only a magnetic aluminum core 86a having a resin 84 and an aluminum alloy 85;
shows a model using a magnetic aluminum core 86b that increases the heat dissipation area to the outside air and the cross-sectional area of the heat transfer path. And (b) in Figure 8(b)
, (C) and (D) show the temperature distribution of each part when each coil 81 is heated.

As is clear from FIG. 8(b), the model (b) using magnetic aluminum has better heat dissipation than the conventional model (a), and the temperature of each part is lower. Compared to the above model (b), the model (c) corresponding to a power distributor in which the housing body is formed by a peripheral core has better heat dissipation and lower temperature because the resin 84 and aluminum alloy 85 are replaced with magnetic aluminum. I can see that Model (d) having the specially shaped core 86b exhibits even better heat dissipation characteristics due to its increased heat dissipation area and heat transfer passage cross-sectional area. Therefore, the embodiment shown in FIG. 6 exhibits heat dissipation characteristics similar to model (d).

[Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below.

That is, in the closed magnetic circuit coil of the present invention, the Joule heat generated in the coil is transmitted to the peripheral core of the cylindrical body of the closed magnetic circuit core, and is dissipated to the outside air from the outer surface of the core, resulting in better heat conduction than in the past. At the same time, a large heat dissipation area is ensured, resulting in good heat dissipation, and therefore stable operation of the closed magnetic circuit coil can be ensured.

Furthermore, a closed magnetic circuit core made of magnetic aluminum has higher thermal conductivity than a conventional laminated steel plate core, so that even better thermal conductivity can be obtained.

Therefore, when the closed magnetic circuit coil is built into a power distributor as an ignition coil, the high temperature of the closed magnetic circuit coil can be suppressed due to good heat dissipation characteristics.

In particular, if the housing body of the power distribution device is composed of a peripheral core, heat is radiated directly to the outside air without going through a separate housing, ensuring stable ignition without causing the closed magnetic circuit coil to reach high temperatures. be able to. Furthermore, if the peripheral core is provided with heat dissipation fins, the heat dissipation performance will be even better.

In addition, in the inventions described in claims 1 to 11, the number of parts is smaller and the structure is simpler than in the past, and according to the method described in claim 7, it can be easily manufactured and is inexpensive. A closed magnetic circuit coil can be provided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the closed magnetic circuit coil of the present invention, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. FIG. 4 is a longitudinal sectional view of a housing main body portion of another embodiment of the closed magnetic circuit coil built-in power distributor according to the present invention, and FIG. 5 is a longitudinal sectional view of a housing main body portion shown in FIG. 4. FIG. 6 is a cross-sectional view of a housing main body portion of still another embodiment of the closed magnetic circuit coil built-in power distributor of the present invention, and FIG. FIG. 8 is a sectional view showing another embodiment of the coil. FIG. 8 shows the temperature distribution when the structures of the prior art and each embodiment of the present invention are modeled. FIG. 8(a) shows the temperature distribution of each structure. The configuration diagram shown in FIG. 8(b) is a temperature distribution diagram corresponding to each model in the configuration diagram. 1...Closed magnetic circuit coil. 2...Housing body. 3... Cap. 4... Drive shaft (shaft). 10...Ignition coil. 11.111...Closed magnetic circuit core. 11a, 110a, 1lla... peripheral core. 11b, 111b... central core. tic...end face core. lid...air gap, 11e...through hole. 12...Case. 13...Primary coil, 14...Secondary coil. 15...Primary bobbin, 16...Secondary bobbin. 17...Resin part. 20...Centrifugal advance mechanism. 30...Signal generator. 4o... Negative pressure advance mechanism. 50...Power distribution section. 70...igniter. 100...Closed magnetic circuit coil. 200...Housing body. 201a...radiating fin

Claims (11)

[Claims] (1) Magnetism that includes a peripheral core of a cylindrical body, a central core extending in the axial direction of the central portion of the peripheral core, and an end core that magnetically couples the central core and the peripheral core to form a closed magnetic path. 1. A closed magnetic path coil comprising: a closed magnetic path core; and a primary coil and a secondary coil wound around the central core of the closed magnetic path core. (2) A peripheral core of the bottomed cylinder, a central core of the cylinder extending axially from the bottom surface of the peripheral core toward the open end and having a through hole in the axial direction, and an end of the central core and the peripheral edge. a closed magnetic path core made of a magnetic material that includes an end face core of a lid that magnetically couples the open end of the core to form a closed magnetic path; a primary coil wound around the central core of the closed magnetic path core; A closed magnetic circuit coil characterized by comprising a secondary coil wound around the coil. (3) The magnetic material forming the closed magnetic circuit core is magnetic aluminum formed by mixing aluminum powder and iron powder and then press-molding the primary coil and the secondary coil in the space defined by the closed magnetic circuit core. 3. The closed magnetic circuit coil according to claim 1, wherein a gap formed between the coil and the next coil is filled with a synthetic resin. (4) The magnetic material forming the closed magnetic circuit core is a mixture of synthetic resin and iron powder and then heated and hardened, and the magnetic material forms the primary coil and the secondary coil within the space defined by the closed magnetic circuit core. 3. The closed magnetic circuit coil according to claim 1, wherein a gap formed between the coils is filled with a synthetic resin. (5) The closed magnetic circuit coil according to claim 1 or 2, wherein radiation fins are formed on the outer peripheral surface of the cylindrical body of the peripheral core. (6) A cylindrical primary bobbin around which the primary coil is wound and which has a through hole in the axial direction, and a cylinder which has a through hole in the axial direction to accommodate the primary bobbin and around which the secondary coil is wound. 3. A secondary bobbin according to claim 2, further comprising: a through-hole of the primary bobbin is fitted into the central core, and the primary bobbin and the secondary bobbin are housed in the peripheral core. Closed magnetic circuit coil. (7) Magnetic aluminum, which has been pressure-formed after mixing aluminum powder and iron powder, is cold-forged to form a peripheral core of a bottomed cylindrical body and to extend it in the axial direction from the bottom surface of the peripheral core toward the open end. forming a central core of a cylindrical body having a through hole, inserting a primary coil and a secondary coil wound into a cylindrical shape into the central core, and then filling the gap in the peripheral core with a thermosetting resin; A method for manufacturing a closed magnetic circuit coil, characterized in that an end face core of a lid body that magnetically couples an end of the central core and an open end of the peripheral core is attached to the open end of the peripheral core. (8) A peripheral core of a bottomed cylindrical body, a central core of the cylindrical body extending axially from the bottom surface of the peripheral core toward the open end and having a through hole in the axial direction, and an end of the central core and the peripheral edge. a closed magnetic path core made of a magnetic material that includes an end face core of a lid that magnetically couples the open end of the core to form a closed magnetic path; a primary coil wound around the central core of the closed magnetic path core; It has a closed magnetic circuit coil that includes a secondary coil wound around the coil, and a shaft that rotates in synchronization with the internal combustion engine is inserted into the through hole of the central core, and the closed magnetic circuit coil is housed in the housing. A power distributor with a built-in closed magnetic circuit coil. (9) The housing includes a cap that is a cylinder with a bottom, and a housing body that is a cylinder with a bottom and has an opening end that joins to the open end of the cap and an insertion hole that supports the shaft at the bottom, 9. The closed magnetic circuit coil built-in arrangement according to claim 8, wherein at least a cylindrical portion of the housing main body is constituted by the peripheral core, and the shaft is inserted into and supported by a through hole of the central core. Electric appliances. (10) The housing includes a cap that is a cylinder with a bottom, and a housing body that is a cylinder with a bottom and has an opening end that connects to the open end of the cap and an insertion hole that supports the shaft at the bottom, 9. The power distributor with a built-in closed magnetic circuit coil according to claim 8, wherein the cylindrical body portion of the cap is constituted by the peripheral core, and the shaft is inserted into and supported by a through hole of the central core. (11) The power distributor with a built-in closed magnetic circuit coil according to claim 9, characterized in that radiation fins are formed on the outer peripheral surface of the peripheral core constituting the housing main body.