JP5083258B2 - Reactor - Google Patents

Description

  The present invention relates to a reactor having a core made of a magnetic powder mixed resin.

  For example, an inverter mounted on an electric vehicle or a hybrid vehicle incorporates a reactor for boosting the battery voltage. In such a reactor, as shown in FIG. 8, in recent years, a reactor in which a magnetic powder mixed resin made of a resin mixed with a magnetic powder is filled around a coil 92 as a core 93 is realized as a cost reduction by reducing the number of parts. 9 has been proposed (Patent Documents 1 to 3).

JP 2008-218724 A JP 2008-192877 A JP 2008-166503 A

However, in the reactor 9, the coil 92 is embedded in the magnetic powder mixed resin (core 93) and the periphery is surrounded, and thus it is difficult to efficiently dissipate the heat generated from the coil 92. There's a problem.
In order to solve such a problem, a means for improving the thermal conductivity of the core 93 by mixing an additive such as silica or alumina into the core 93 can be considered. However, if the composition of the core 93 is greatly changed, the magnetic characteristics of the reactor 9 will change, so there is a limit to the mixing of additives, and it is difficult to sufficiently improve the heat dissipation efficiency.

  This invention is made | formed in view of this problem, and it aims at providing the reactor excellent in heat dissipation.

The present invention is a reactor comprising a coil that generates magnetic flux when energized, a core made of magnetic powder mixed resin filled around the coil, and a case that houses the coil and the core,
Between the coil and the case, Ri interposed a heat transfer member having high thermal conductivity than the core with contacts on both tare,
The heat transfer member is formed on substantially the entire circumference in the winding direction of the coil, and a slit is formed in a part thereof, and the slit is formed in the radial direction of the coil. Reactor.
(Claim 1).

The heat transfer member is interposed between the coil and the case so as to be in contact with both. Therefore, the heat generated in the coil can be transmitted to the case via the heat transfer member and radiated. That is, since the heat transfer member has a higher thermal conductivity than the core, heat dissipation from the coil to the case can be improved as compared with the case where no heat transfer member is provided. As a result, the temperature rise of the reactor can be effectively suppressed.
In this case, since it is not necessary to consider the core material from the viewpoint of heat dissipation, the core material can be selected from the viewpoint of magnetic characteristics. Therefore, it is possible to easily obtain a reactor with high inductance while ensuring heat radiation by the heat transfer member.

  As described above, according to the present invention, it is possible to provide a reactor excellent in heat dissipation.

The cross section parallel to the (A) winding axis | shaft of a reactor in Example 1, (A) AA arrow directional cross-sectional view of (A). Sectional drawing of the slit vicinity of the heat-transfer member in Example 1. FIG. Explanatory drawing which shows the manufacturing method of the reactor in Example 1. FIG. Explanatory drawing which shows the manufacturing method of the reactor in Example 1 following FIG. Explanatory drawing which shows the manufacturing method of the reactor in Example 1 following FIG. Sectional drawing of the slit vicinity of the heat-transfer member in a reference example . The cross section parallel to the (A) winding axis | shaft of a reactor in Example 2 , (B) The BB arrow directional cross-sectional view of (A). Sectional view parallel to (A) winding axis of a conventional reactor, (B) A cross-sectional view taken along line CC of (A).

In the present invention, as the magnetic powder mixed resin, for example, a resin obtained by mixing a magnetic powder such as iron powder in a thermosetting resin such as an epoxy resin or a resin such as a thermoplastic resin can be used.
Moreover, it is preferable that the said heat-transfer member consists of material with high heat conductivity, such as metals, such as aluminum and its alloy, for example.

Further, the heat transfer member, that is formed in more than half the entire circumference of the winding direction of the coil.
Thereby , heat dissipation through the heat transfer member can be efficiently performed.

Further, the heat transfer member is formed in substantially the entire circumference of the winding direction of the coil, ing to form a slit in a part thereof.
Thereby, since heat can be radiated through the heat transfer member over substantially the entire circumference of the coil, the coil can be radiated substantially uniformly and efficiently. Further, by providing the slit, it is possible to suppress the generation of eddy current in the heat transfer member. That is, when the metal heat transfer member is provided over the entire circumference of the coil, an eddy current in a direction opposite to the coil current may be generated in the heat transfer member when a current is passed through the coil. In this case, the temperature of the reactor is increased due to heat generation due to eddy current loss, and the magnetic characteristics of the reactor are affected, which may make it difficult to obtain a desired inductance. Therefore, by providing the slits to prevent the formation of eddy currents, the above problems can be prevented.

Further, the heat transfer member has an outer peripheral surface in the radial direction of the coil, that are arranged in contact with the inner wall surface of the case facing the outer peripheral surface preferably (claim 2).
In this case, the heat transfer member can be used as a positioning member for the coil case when the reactor is manufactured.

Further, the heat transfer member comprises a winding axis direction of the end face of the coil, which may be arranged in contact with the inner wall surface of the case facing the end surface (claim 3).
Also in this case, the heat transfer member can be used as a positioning member for the coil case when the reactor is manufactured.

Moreover, it is preferable that the said heat-transfer member consists of nonmagnetic materials (Claim 4 ).
In this case, by arranging the heat transfer member in the middle of the magnetic circuit, the nonmagnetic heat transfer member functions as a gap of the core, and magnetic saturation can be suppressed.

Example 1
A reactor according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the reactor 1 of the present example accommodates a coil 2 that generates magnetic flux when energized, a core 3 made of a magnetic powder mixed resin filled around the coil 2, and the coil 2 and the core 3. Case 4 is formed.
Between the coil 2 and the case 4, a heat transfer member 5 that is in contact with both and has a higher thermal conductivity than the core 3 is interposed.

  The heat transfer member 5 is disposed in contact with the radially outer peripheral surface 21 of the coil 2 and the inner wall surface 41 of the case 4 facing the outer peripheral surface 21. Further, the heat transfer member 5 is in contact with a substantially central position in the winding axis direction of the coil 2. The coil 2 may be covered with an insulating coating (not shown), but in that case, the heat transfer member 5 comes into contact with the insulating coating.

  As shown in FIG. 1B, the heat transfer member 5 is formed on more than half of the entire circumference of the coil 2 in the winding direction. More specifically, the heat transfer member 5 is formed on substantially the entire circumference in the winding direction of the coil 2. As shown in FIGS. 1B and 2, a slit 51 is formed in a part of the heat transfer member 5. The slits 51 are formed across the entire width of the heat transfer member 5 in the radial direction of the coil 2, and are partially evenly arranged at four locations in the circumferential direction.

  The heat transfer member 5 is made of a nonmagnetic metal having excellent thermal conductivity such as aluminum. The heat transfer member 5 is disposed in the middle of the magnetic circuit formed by energization of the coil 2 and functions as a gap of the core 3, thereby suppressing magnetic saturation. And the thickness of the heat-transfer member 5 is designed to such an extent that this magnetic saturation is effectively suppressed. For example, the thickness of the heat transfer member 5 is preferably about 5 to 10 mm.

In addition, as the magnetic powder mixed resin constituting the core 3, for example, a resin obtained by mixing magnetic powder such as iron powder into a resin such as a thermosetting resin such as an epoxy resin or a thermoplastic resin can be used.
The case 4 can be made of, for example, aluminum or an alloy thereof.

In manufacturing the reactor 1 of this example, as shown in FIG. 3, the slurry 30 of the magnetic powder mixed resin, which is the raw material of the core 3, is poured into the case 4 to about half. On the other hand, a subassembly in which the heat transfer member 5 is bonded and fixed to the outer periphery of the coil 2 is prepared. Adhesion between the coil 2 and the heat transfer member 5 uses, for example, an adhesive having excellent thermal conductivity.
Next, as shown in FIG. 4, the subassembly of the coil 2 and the heat transfer member 5 is inserted into the case 4, and the coil 2 is submerged in the slurry 30 to the portion where the heat transfer member 5 is fixed. As a result, the heat transfer member 5 is placed in close contact with the surface of the slurry 30.
Next, the slurry 30 of the magnetic powder mixed resin is further filled in the case 4, and the coil 2 and the heat transfer member 5 are buried in the slurry 30. Thereafter, the slurry 30 is cured.
Thereby, the reactor 1 as shown in FIG. 1 can be obtained.

In this example, the method of forming the core 3 by injecting the slurry 30 of the magnetic powder mixed resin directly into the case 4 is shown. However, the core 3 in a state where the coil 2 is embedded by using another forming die. After forming and demolding, the reactor 1 can be obtained by inserting it into the case 4 by shrink fitting or the like.
In addition, various methods can be used about the manufacturing method of the reactor 1 of this example.

Next, the function and effect of this example will be described.
As shown in FIG. 1, a heat transfer member 5 is interposed between the coil 2 and the case 4 so as to be in contact with both. Therefore, the heat generated in the coil 2 can be transmitted to the case 4 via the heat transfer member 5 to be radiated. That is, since the heat transfer member 5 has a higher thermal conductivity than the core 3, the heat dissipation from the coil 2 to the case 4 can be improved as compared with the case where the heat transfer member 5 is not provided. As a result, the temperature rise of the reactor 1 can be effectively suppressed.
Further, in this case, since it is not necessary to consider the material of the core 3 from the viewpoint of heat dissipation, the material of the core 3 can be selected from the viewpoint of magnetic characteristics. Therefore, it is possible to easily obtain the reactor 1 having a high inductance while ensuring heat radiation by the heat transfer member 5.

Moreover, since the heat transfer member 5 is formed in more than half of the entire circumference in the winding direction of the coil 2, the heat transfer through the heat transfer member 5 can be efficiently performed.
The heat transfer member 5 is formed on substantially the entire circumference in the winding direction of the coil 2 and is formed with a slit 51 in a part thereof. Therefore, heat can be radiated through the heat transfer member 5 over substantially the entire circumference of the coil 2, and the coil 2 can be radiated substantially uniformly and efficiently. Further, by providing the slit 51, it is possible to suppress the generation of eddy current in the heat transfer member 5. That is, when the metal heat transfer member 5 is provided over the entire circumference of the coil 2, an eddy current in a direction opposite to the current of the coil 2 may be generated in the heat transfer member 5 when a current is passed through the coil. In this case, the temperature of the reactor 1 is increased due to heat generation due to eddy current loss, and the magnetic characteristics of the reactor 1 are affected, which may make it difficult to obtain a desired inductance. Therefore, by providing the slits 51 to prevent the formation of eddy currents, the above problems can be prevented.

  The heat transfer member 5 is disposed in contact with the outer peripheral surface 21 in the radial direction of the coil 2 and the inner wall surface 41 of the case 4 facing the outer peripheral surface 21. Therefore, the heat transfer member 5 can also be used as a positioning member for the case 2 of the coil 2 when the reactor 1 is manufactured. That is, by providing the heat transfer member 5, the position of the coil 2 is determined with respect to the case 4 in the radial direction of the coil 2.

  Further, since the heat transfer member 5 is made of a nonmagnetic material and is disposed in the middle of the magnetic circuit, the nonmagnetic heat transfer member 5 functions as a gap of the core 2 and can suppress magnetic saturation.

  As described above, according to this example, it is possible to provide a reactor having excellent heat dissipation.

( Reference example )
In this example, as shown in FIG. 6, the groove 52 is formed in a part of the heat transfer member 5 formed on the entire circumference in the winding direction of the coil 2.
That is, in the state substantially the same as FIG. 1B in the first embodiment, the heat transfer member 5 is provided, and the slit 51 shown in FIG. A groove 52 as shown is formed.
Others are the same as in the first embodiment.

Also in this example, since heat can be radiated through the heat transfer member 5 over substantially the entire circumference of the coil 2, the coil 2 can be radiated substantially uniformly and efficiently. Further, by providing the groove 52, it is possible to obtain an eddy current suppressing effect substantially similar to the slit 51 in the first embodiment.
In addition, the same effects as those of the first embodiment are obtained.

( Example 2 )
In this example, as shown in FIG. 7, the heat transfer member 5 is disposed in contact with the end surface 22 in the winding axis direction of the coil 2 and the bottom surface 42 that is the inner wall surface of the case 4 facing the end surface 22. It is an example of 1.
In the case of this example, as the heat transfer member 5, four arc-shaped members having substantially the same diameter as the coil 2 are bonded and fixed to the end face 22 of the coil 2, and four slits 51 are provided between the heat transfer members 5. The pieces are arranged evenly.
The height of the heat transfer member 5 in the winding axis direction of the coil 2 is preferably equal to the distance between the other end surface 23 of the coil 2 and the upper surface 31 of the core 3.

When manufacturing the reactor 1 of this example, it can carry out as follows, for example. First, the heat transfer member 5 fixed to the end face 22 of the coil 2 is placed in the case 4. Next, the slurry of the magnetic powder mixed resin is filled in the case 4, and the coil 2 and the heat transfer member 5 are buried in the slurry. Next, the reactor 1 shown in FIG. 7 is obtained by curing the slurry.
Others are the same as in the first embodiment.

In the case of this example, when manufacturing the reactor 1, the coil 2 can be positioned with respect to the case 4 in the winding axis direction of the coil 2 using the heat transfer member 5.
In addition, the same effects as those of the first embodiment are obtained.

In addition, the aspect which combined Example 1 and Example 2 can also be taken. That is, the heat transfer member 5 can be disposed in contact with both the outer peripheral surface 21 in the radial direction of the coil 2 and the end surface 22 in the winding axis direction.
In this case, heat dissipation can be further improved, and positioning with respect to the case 4 can be easily performed in both the radial direction and the winding axis direction of the coil 2.

In addition to the states shown in the first and second embodiments, the posture of the coil 2 with respect to the case 4 can be variously arranged such that the winding axis direction is orthogonal to the opening direction of the case 4. Conceivable.
As for the shape of the coil 2, in addition to the annular as in Examples 1 and 2, oval, such as a rectangle, it can take various shapes.
The present invention can be similarly applied to reactors of these various modes.

1 Reactor 2 Coil 3 Core 4 Case 5 Heat transfer member

Claims (4)

A reactor comprising a coil that generates magnetic flux when energized, a core made of a magnetic powder mixed resin filled around the coil, and a case that houses the coil and the core,
Between the coil and the case, Ri interposed a heat transfer member having high thermal conductivity than the core with contacts on both tare,
The heat transfer member is formed on substantially the entire circumference in the winding direction of the coil, and a slit is formed in a part thereof, and the slit is formed in the radial direction of the coil. Reactor. The reactor according to claim 1, wherein the heat transfer member is disposed in contact with an outer peripheral surface in a radial direction of the coil and an inner wall surface of the case facing the outer peripheral surface . 3. The reactor according to claim 1, wherein the heat transfer member is disposed in contact with an end surface of the coil in a winding axis direction and an inner wall surface of the case facing the end surface . The reactor according to claim 1, wherein the heat transfer member is made of a nonmagnetic material .

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