JP2015126051A - Reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor including a coil configured to be embedded within a mold body, in which the mold body has favorable elasticity and thereby excellent reduction in NV (noise and vibration) is achieved, and also formability of the mold body is good.SOLUTION: A reactor 10 is formed of: a mold body 2 formed of a composite material obtained by mixing composite powder 5 including magnetic powder 3 coated with a resin layer 4, and addition curing type silicone rubber; and a coil 1 embedded in the mold body 2. The silicone rubber is favorably liquid silicone rubber.

Description

  The present invention relates to a reactor.

  More specifically, a reactor is applied as a component of a power conversion device such as an in-vehicle DC-DC converter, as a circuit component that performs voltage step-up or step-down control in the power conversion device.

  There are various types of reactors. For example, a U-shaped core and an I-shaped core are assembled in a ring shape through a gap, and a coil is formed around them. And a form in which a molded resin body is formed in the case.

  As another form, there is a reactor in which a resin core material is molded into a coil and the coil is embedded in the mold body.

  In this type of reactor, a composite material in which magnetic powder and a resin are mixed is generally used as the resin core material for forming the reactor, and a proposal relating to such a reactor is disclosed in Patent Document 1.

  And as resin which forms a resin core material, both the thermosetting resin shape | molded by heat hardening and the thermoplastic resin shape | molded by cooling hardening are applied. Among them, the method by injection molding is preferable because the molding time may be short.

  By the way, a composite material in which a resin and a magnetic powder such as soft magnetic powder are mixed is applied as a resin core material, and this composite material is formed by injection molding so as to cover a coil to manufacture a reactor. As the resin, a thermoplastic resin having a high thermal conductivity, an injection-moldable silicone resin, or the like is applied. According to the mold body made of silicone resin, both the NV (noise and vibration) reduction during driving of the reactor and the heat dissipation from the coil to the cooler are improved.

  When filling a soft magnetic powder or a filler with high thermal conductivity, or molding these by injection molding, the viscosity of these materials often tends to increase, but it is inherently somewhat resinous. If it is not a low-viscosity material, sufficient filling properties cannot be guaranteed. In addition, as a countermeasure against NV described above, the mold body needs to have a certain degree of elasticity.

  Examples of a material that can satisfy such various restrictions include silicone rubber among silicone resins.

  As for the silicone rubber, there are those that react with an organic peroxide as a catalyst (curing agent) and those that undergo an addition reaction using a transition metal compound such as platinum as a catalyst. Among these, since the former produces by-products such as alcohol and benzoic acid during the reaction, there is a concern about the influence on the coil constituting the reactor and the soft magnetic powder constituting the mold body.

JP 2013-211151 A

  The present invention has been made in view of the above problems, and relates to a reactor in which a resin material is molded into a coil and the coil is embedded in the mold body. It is an object of the present invention to provide a reactor that is excellent in vibration reduction and has good moldability and does not produce by-products that can affect the coil or the like.

  In order to achieve the above object, a reactor according to the present invention comprises a mold body made of a composite material obtained by mixing a composite powder obtained by coating magnetic powder with a resin layer and an addition-curing silicone rubber, and It is formed from a coil embedded in the mold body.

  The reactor of the present invention is a rubber that is obtained by applying a composite material obtained by mixing a composite powder in which magnetic powder is coated with a resin layer and an addition-curing silicone rubber as a material constituting the mold body. It is excellent in NV reduction property due to the damping effect due to the elasticity of the resin, and it is possible to suppress the inhibition of curing of the silicone rubber by applying a composite powder in which magnetic powder is previously coated with a resin layer. This is because, for example, impurities such as phosphorus and sulfur contained in the soft magnetic powder are surrounded by a resin layer formed on the surface of the soft magnetic powder so that these impurities appear on the surface when the silicone rubber is cured. It is because it is suppressed.

  In applying the soft magnetic powder as the magnetic powder, an iron group metal such as Fe, Co, or Ni, or an alloy powder containing Fe as a main component can be applied as the soft magnetic powder.

  Moreover, as the resin layer formed on the surface of the magnetic powder, for example, a silicone resin mainly composed of trifunctional silicone can be applied.

  Furthermore, regarding addition-curable silicone rubbers that serve as binders, the addition reaction of silane having a His triple bond to olefins or acetylenes is used as the addition-curing reaction. Moreover, Pt etc. can be used for a catalyst (curing agent), and the silicone rubber which has a linear polymer whose degree of polymerization is about 100-2000 as a main component is applicable.

  Here, the silicone rubber is preferably a liquid silicone rubber.

  Silicone rubber has a main skeleton of a siloxane bond structure in which a polymer is formed by alternately bonding silicon and oxygen. Depending on the presence and type of additives such as vulcanizing agents, sheet rubber and paste There are liquid and liquid products.

  Among these, by using liquid silicone rubber, good fluidity can be ensured even when injection molding is performed as a composite material with magnetic powder, and good moldability can be guaranteed.

  Further, an embodiment in which a nonmagnetic filler is contained in the mold body may be used.

  Although the thermal conductivity of the silicone polymer itself is as small as 0.16 W / mK, the amount of this mixture (by mixing thermally conductive fillers such as silica, alumina, boron nitride, silicon nitride, silicon carbide, magnesium oxide) According to the mixing ratio), the silicone has high heat dissipation.

  As can be understood from the above description, according to the reactor of the present invention, a composite powder obtained by coating a magnetic powder with a resin layer and an addition curing type silicone rubber are mixed as a material constituting the mold body. By applying this composite material, it is excellent in NV reduction due to the damping effect due to the elasticity of rubber, and silicone due to impurities contained in the magnetic powder because the magnetic powder is pre-coated with a resin layer Inhibition of rubber curing can be suppressed. Further, by using liquid silicone rubber, good fluidity can be ensured even when the composite material is injection-molded, and good moldability can be guaranteed.

(A) is the schematic diagram which showed embodiment of the reactor of this invention, (b) is sectional drawing of the composite powder which forms a mold body.

  Hereinafter, embodiments of a reactor of the present invention will be described with reference to the drawings.

(Embodiment 1 of the reactor)
FIG. 1a is a schematic view showing an embodiment of the reactor of the present invention, and FIG. 1b is a cross-sectional view of a composite material forming a mold body.

  A reactor 10 shown in FIG. 1 a is configured by a coil 1 being embedded in a mold body 2.

  As shown in FIG. 1b, the mold body 2 is formed of a composite material in which a composite powder 5 in which a resin layer 4 is coated around a soft magnetic powder 3 and an addition-curing liquid silicone rubber are mixed. Yes.

  The reactor 10 is manufactured by housing the coil 1 in a molding die (not shown) and injection-molding the composite material 5 forming the mold body 2.

  Here, as the soft magnetic powder 3, an iron group metal such as Fe, Co, or Ni, an alloy powder containing iron as a main component, or the like can be applied. In particular, Fe-Si alloys, Fe-Ni alloys, Fe-Al alloys, Fe-Co alloys, Fe-Cr alloys, Fe-Si-Al alloys, rare earth metals, ferrites, and the like can be applied.

Further, the addition-curable liquid silicone rubber can be represented by the following formula using an addition reaction of a silane having a His triple bond to an olefin or acetylene.
RCH = CH ₂ + HSi≡ → RCH ₂ CH ₂ Si≡

  Examples of the catalyst include Group VIII transition metals such as Ni, Rh, Pd, and Pt, or compounds and complexes thereof. Of these, platinum catalysts such as chloroplatinic acid are suitable.

  The addition-curable liquid silicone rubber is a material mainly composed of a linear polymer having a degree of polymerization of 100 to 2000, and a viscosity of about 50 to 3000 Pa · s is preferable.

  Moreover, as a material of the resin layer 4 (which can also be said to be a liquid silicone rubber curing inhibition suppressing layer) for coating the soft magnetic powder 3, a material having good adhesion to the soft magnetic powder 3 is good and may be an impurity. Some materials, such as organic compounds containing nitrogen, phosphorus, sulfur, etc., ionic compounds of heavy metals such as Sn, Pb, Hg, Bi, As, acetylene groups, etc., are not applicable as materials. . As a material for the resin layer 4, a silicone resin mainly composed of trifunctional silicone such as silicone resin is suitable.

  To outline the manufacturing method of the composite powder 5, for example, the soft magnetic powder 3 and the silicone resin constituting the resin layer 4 are stirred and heated to prepare a solvent in which the silicone resin is dispersed, and then dried. At the same time, a resin layer 4 made of silicone resin is formed around iron by a cross-linking reaction between the silicone resins to produce composite powder 5. By mixing (or mixing) the obtained composite powder 5 and addition-curable liquid silicone rubber with a stirrer, a composite material for molding the mold body 2 is obtained.

  Although the thermal conductivity of the silicone polymer itself is as small as 0.16 W / mK, it can be mixed by mixing thermal conductive fillers such as silica, alumina, boron nitride, silicon nitride, silicon carbide, and magnesium oxide. A mold body having high heat dissipation properties can be obtained according to the amount (mixing ratio).

  According to the reactor 10 in which each component is formed from the above-described various materials, it has a high NV reduction property due to the elastic damping effect of the silicone rubber that constitutes the mold body 2 and depends on impurities that the magnetic powder 3 can contain. Inhibition of curing of the silicone rubber can be suppressed, and even when the composite material is injection-molded, good fluidity is ensured, and good moldability can be ensured.

  Moreover, the present inventors manufactured the following two types of comparative examples for the reactor of the present invention described above, and performed comparative verification with the reactor of the present invention.

(Comparative Example 1)
A composite powder was produced by using iron as the soft magnetic powder and forming a resin layer made of silicone resin around the iron.

  The composite powder and millable silicone rubber were mixed with a stirrer to produce a mixed material, and the mixed material was injection molded around the coil accommodated in the mold to obtain the reactor according to Comparative Example 1.

  In this manufacturing process, the millable silicone rubber has a high viscosity because the degree of polymerization is as high as about 5000 to 10,000, and therefore does not mix well with iron powder. Even if it can be mixed with a stirrer, it does not have good fluidity during injection molding. Therefore, even if adjustments such as increasing the injection pressure or increasing the resin temperature at the time of injection are made, damage to the coil housed in the mold will increase, resulting in difficulty in molding. It was.

(Comparative Example 2)
Without forming a resin layer around soft magnetic powder such as iron, a composite material was manufactured by mixing soft magnetic powder and liquid silicone rubber with a stirrer.

  Here, as the silicone rubber, a two-component mixed type addition-curable silicone rubber was used, and soft magnetic powder was added and mixed to the one containing no catalyst (curing agent) or having a lower viscosity.

  When the liquid containing the liquid A is liquid A and the other is liquid B, a device that supplies liquid A and liquid B, and a device that quantitatively discharges liquid A and liquid B at a desired mixing ratio using a pressure pump A mixing device such as a dynamic mixer or a static mixer that mixes the liquid A and the liquid B, an injection molding machine including a mold closing device and a molding die are prepared, and a coil is accommodated in the molding die. And the silicone rubber in which A liquid and B liquid were mixed was poured in the shaping | molding die, the mold body was shape | molded around the coil, and the reactor concerning the comparative example 2 was obtained.

  In Comparative Example 2, since the surface of the iron powder is not coated with a resin layer, the platinum catalyst in the silicone rubber becomes an impurity, the silicone rubber is inhibited from curing, and the silicone rubber is not sufficiently cured. The mold body could not be formed.

  In contrast to Comparative Examples 1 and 2, according to the reactor of the present invention, a mold is made of a composite material in which a composite powder obtained by coating magnetic powder with a resin layer and an addition-curable liquid silicone rubber are mixed. By forming the body, the inhibition of curing of the silicone rubber is suppressed, the fluidity when the composite material is injection-molded becomes good, and the molded body can be molded around the coil under good moldability. it can.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Coil, 2 ... Mold body, 3 ... Magnetic powder (soft magnetic powder), 4 ... Resin layer, 5 ... Composite powder, 10 ... Reactor

Claims (3)

  It is formed from a composite body formed by mixing a composite powder in which magnetic powder is coated with a resin layer and an addition-curable silicone rubber, and a coil embedded in the mold body. Reactor.   The reactor according to claim 1, wherein the silicone rubber is a liquid silicone rubber.   The reactor according to claim 1, wherein a nonmagnetic filler is contained in the mold body.

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