JP2017050457A - Reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor not including a heat dissipation sealing resin body, where such problems that heat dissipation is hindered and a coil is pressed against the bottom surface of the case, do not occur even when the coil is expanded or contracted thermally.SOLUTION: In a reactor 10 comprising a case 4 constituted of a bottom face 4a and a side face 4b, and a core 1 including a coil 2 disposed in the case 4, a metal plate 6 including a stationary portion 6a and a floating portion 6b is fixed to the inside of the bottom face 4a of the case 4 via the stationary portion 6a, the floating portion 6b is floating from the bottom face 4a via a gap G while the metal plate 6 is in a stationary state, and the core 1 including the coil 2 is placed on the floating portion 6b.SELECTED DRAWING: Figure 1

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.

  As a general configuration form of the reactor, a coil is formed around a U-shaped core or an I-shaped core, and this is accommodated in the case, and a sealing resin body having heat dissipation is provided between the core and the coil and the bottom surface of the case. A form in which a cooler is disposed below the case can be given. Patent Document 1 also discloses a reactor in which a core on which a coil is disposed via a heat dissipating material is placed on a case and bolted to the case via a stay.

  Current reactors are driven at, for example, 10 kHz or less, but by realizing high-frequency drive of about 20 to 30 kHz, low vibration and low noise performance (so-called NV performance), which is important for current reactors, is important. It is guessed that it will disappear. Therefore, it is not necessary to secure a gap between the coil and the case, which is one of the measures for ensuring low vibration and low noise performance, and a reactor having a form in which the coil is in direct contact with the case is expected.

  In this way, when the coil is directly brought into contact with, for example, the bottom surface of the case, heat is directly transmitted from the coil as the heat generation source to the case, so that a reactor having excellent heat dissipation performance can be obtained.

  Thus, while the reactor excellent in heat dissipation performance is anticipated, in the reactor of the form in which the coil is directly in contact with the bottom surface of the case, there are concerns about some problems described below. This will be described with reference to FIGS.

  In the reactor RT shown in FIG. 4, a core Co on which a coil Ci is disposed via a bobbin Bo is fastened to a case Ca via a stay S with a bolt B, and a lower end Ci ′ of the coil Ci is a bottom surface of the case Ca. A cooler Cl that directly abuts on Ca ′ and in which the refrigerant R circulates is disposed below the case Ca to constitute the whole. That is, in the illustrated reactor RT, the sealing resin body that is a heat radiating material is not molded in the case Ca.

  Since the lower end Ci ′ of the coil Ci, which is a heat generation source, is in direct contact with the bottom surface Ca ′ of the case Ca, the heat generated in the core Co and the coil Ci is quickly transferred to the bottom surface Ca ′ of the case Ca (X1). Direction), and cooled by the cooler Cl.

Japanese Patent Laying-Open No. 2015-090912

  According to the reactor RT of the form shown in FIG. 4, the heat radiation performance is markedly improved as compared with the reactor of the form where heat is transferred from the core-coil to the bottom surface of the case and the cooler via the sealing resin body. However, various problems may occur due to thermal expansion and contraction of the coil.

  FIG. 5 shows a state where the coil Ci is thermally contracted. As shown in the figure, in a low temperature atmosphere, the coil Ci is thermally contracted (Y1 direction), the abutted coil Ci is separated from the bottom surface Ca ′ of the case Ca, and the coil Ci is separated from the bottom surface Ca ′. A gap G is generated.

  Since the gap G is generated between the coil Ci and the bottom surface Ca 'of the case Ca in this way, there is no heat dissipation route from the coil Ci to the bottom surface Ca' or the cooler Cl, and the heat dissipation performance of the reactor RT is greatly impaired.

  On the other hand, FIG. 6 shows a state where the coil Ci is thermally expanded. As shown in the figure, when the coil Ci is thermally expanded in a high temperature atmosphere (Y2 direction), the thermally expanded coil Ci is pressed against the bottom surface Ca ′ of the case Ca (pressing force P). Stress is generated inside the coil Ci, and the coil Ci may be damaged by the internal stress.

  Further, the core Co is lifted upward by the thermal expansion of the coil Ci, and accordingly, the stay S is also pulled upward and plastically deformed, which may lead to loosening of the fastening portion by the bolt B and damage to the fastening portion.

  The present invention has been made in view of the above-described problems, and relates to a reactor that does not include a heat-dissipating sealing resin body, and even when the coil is thermally expanded or contracted, the heat dissipation is hindered or the coil is An object is to provide a reactor that does not cause a problem of being pressed against the bottom surface.

  In order to achieve the above object, a reactor according to the present invention is a reactor including a case configured by a bottom surface and a side surface, and a core including a coil disposed in the case, and includes a fixed portion and a floating portion. The provided metal plate is fixed to the inside of the bottom surface of the case via the fixing portion, and the floating portion is in a state of floating through the gap from the bottom surface in the fixed state of the metal plate, and the core including the coil is floated It is placed on the part.

  The reactor of this invention has the characteristics in the structure which mounted the core which comprises a coil in the bottom face of the case through the metal plate provided with the fixing | fixed part and the floating part. Here, the metal plate can be formed from, for example, a leaf spring.

  Since the reactor of the present invention does not form a heat-dissipating sealing resin body in the case, the material cost of the sealing resin body can be reduced, the potting process of the sealing resin material can be reduced, and the weight of the entire reactor can be reduced. it can.

  The metal plate on which the core and the coil are placed has various forms as long as it has a fixed part and a floating part. For example, there is a fixed part in the center of the metal plate, there are two floating parts on the left and right sides of the fixed part, and an annular core is placed on the left and right floating parts, and there are fixed parts on the left and right ends of the metal plate A form having a flat floating part at the center, a form having a fixed part at the left and right ends of the metal plate, and a form having a floating part curved upward at the center can be exemplified.

  Since the floating part is in a state of floating through the gap from the bottom surface, even when the coil placed on the floating part is thermally expanded, the floating part is displaced downward by the expansion of the coil, The coil is not pressed against the bottom of the case.

  On the other hand, when the coil placed on the floating portion is thermally shrunk, there is still a gap between the coil and the floating portion and the bottom surface of the case, but the heat dissipation of the coil-metal plate fixing portion-case bottom surface is still present. Since the route is secured, the heat dissipation of the reactor is not hindered.

  Also in the reactor of this invention, the form by which the cooler which a refrigerant | coolant recirculates | circulates below the bottom face of a case is desirable. Moreover, it is preferable that the stay connected to the bobbin interposed between the core and the coil is bolted to the side surface of the case.

  As can be understood from the above description, according to the reactor of the present invention, the core including the coil is placed on the bottom surface of the case via the metal plate including the fixing portion and the floating portion, and the metal plate is fixed. The floating part is in a state where it floats from the bottom through a gap, so that the sealing resin body with heat dissipation can be discarded, and even when the coil is thermally expanded or contracted, the heat dissipation is guaranteed, There can be no problem that the coil is pressed against the bottom of the case and damaged.

It is a longitudinal section of an embodiment of a reactor of the present invention. It is the II-II arrow line view of FIG. 1, Comprising: It is the longitudinal cross-sectional view seen from the direction orthogonal to FIG. (A), (b), (c) is a schematic diagram illustrating an embodiment of a metal plate. It is a longitudinal cross-sectional view of embodiment of the conventional reactor. It is the longitudinal cross-sectional view which showed the state which the coil thermally contracted in the conventional reactor. It is the longitudinal cross-sectional view which showed the state which the coil expanded thermally in the conventional reactor.

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

(Reactor embodiment)
FIG. 1 is a longitudinal sectional view of an embodiment of a reactor according to the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG. 1 as viewed from a direction orthogonal to FIG. FIGS. 3A, 3B, and 3C are schematic diagrams illustrating an embodiment of a metal plate.

  The illustrated reactor 10 is roughly composed of a case 4, a core 1 in which a coil 2 is disposed via a bobbin 3 made of insulating resin, and a cooler 5 that is disposed below the case 4 and in which a refrigerant R circulates. It is configured.

  The core 1 has a U-shaped core and an I-shaped core formed in a substantially ring shape via a gap plate (not shown), and is made of a resin, soft magnetic powder, and the like. Here, as the soft magnetic powder, iron group metals such as Fe, Co, and Ni, alloy powders containing iron as a main component, and 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.

  On the other hand, the resin may be either a thermosetting resin or a thermoplastic resin, but it is preferable to apply a thermoplastic resin that can eliminate the need for a curing furnace and can be injection-molded to reduce manufacturing time. . Examples of the thermoplastic resin to be applied include polyamide, polyester, polyphenylene sulfide, polyether ether ketone, polyethylene, polypropylene, methacryl, and polyimide resin.

The gap plate can be formed of ceramics such as alumina (AL ₂ O ₃ ) or zirconia (ZrO ₂ ). If the electromagnetic characteristics of the reactor, that is, the inductance can be ensured with the structure without the gap plate, the interposition of the gap plate between the cores is unnecessary.

  The coil 2 is composed of a copper conducting wire and an insulating coating such as an enamel coating formed around the conducting wire, and a rectangular wire with a high space factor is suitable.

  The cooler 5 has a flow path 5a formed therein, and cools the heat transferred by the refrigerant R flowing back through the flow path 5a. Here, as the refrigerant, cooling water or cooling air from a radiator or the like can be applied.

  The case 4 is formed of aluminum or an alloy thereof, and includes a bottom surface 4a and, for example, four side surfaces 4b.

  On the bottom surface 4a of the case 4, a central fixed portion 6a and a floating portion 6b on the left and right of the fixed portion 6a are formed, and a metal plate 6 formed of a leaf spring is fixed via the fixed portion 6a.

  The metal plate 6 can be formed from aluminum, iron, copper, or an alloy thereof, but is preferably formed from a metal material having good thermal conductivity such as SUS304-CSP and SUS301-CSP. Further, the metal plate 6 is preferably a metal plate having a high wear resistance by performing a chrome plating process on the surface thereof. Furthermore, the thickness of the metal plate 6 is preferably 0.5 mm or more from the viewpoint of long-term reliability, and is preferably 3 mm or less in order to eliminate the need for excessive space when assembling the parts.

  The left and right coils 2, 2 disposed around the annular core 1 are placed on the left and right floating portions 6b, 6b, respectively. In this state where the coil 2 is placed on the floating portion 6b, the floating portion 6b is in a state of floating through the gap G from the bottom surface 4a. For example, it is preferable to have a gap G having a height of about 10 μm.

  The core 1 is fastened to the side surface 4 b of the case 4 with bolts 8 via a stay 7 connected to the bobbin 3 interposed between the core 1 and the coil 2.

  Since the floating part 6b of the metal plate 6 is in a state of floating through the gap G from the bottom surface 4a, the coil 2 placed on the floating part 6b is thermally expanded (Y2 direction in FIG. 1). The floating portion 6b is simply displaced downward (Z2 direction) due to the expansion of the coil 2, and the coil 2 is not pressed against the bottom surface 4a of the case 4.

  On the other hand, when the coil 2 placed on the floating portion 6b is thermally contracted (in the Y1 direction in FIG. 1), although there is still a gap G between the coil 2 and the floating portion 6b and the bottom surface 4a of the case 4, Since the heat dissipation route (X2 direction in FIG. 1) of the coil 2-the floating portion 6b of the metal plate 6-the fixed portion 6a-the bottom surface 4a of the case 4 is ensured, the heat dissipation of the reactor 10 is not hindered. .

  Next, another embodiment of the metal plate will be described with reference to FIG.

  The metal plate 6A shown in FIG. 3A has fixing portions 6a and 6a at the left and right ends, a flat floating portion 6b at the center, and a gap G between the floating portion 6b and the bottom surface 4a. It is a form.

  Also with this metal plate 6A, the thermal expansion of the coil 2 is absorbed by the displacement of the floating portion 6b, and the coil 2 is not pressed against the bottom surface 4a. In addition, even when the coil 2 is thermally contracted, a heat radiation route through the fixed portion 6a is guaranteed.

  Further, the metal plate 6B shown in FIG. 3B has a separate fixing portion 6a at the center in addition to the fixing portions 6a and 6a at the left and right ends, and a flat floating portion 6b between the fixing portions 6a and 6a. Yes, the gap G is interposed between the floating portion 6b and the bottom surface 4a.

  In this embodiment, the left and right straight portions of the annular core 1 are placed on the floating portions 6b.

  Further, the metal plate 6C shown in FIG. 3C has fixed portions 6a and 6a at the left and right ends, a floating portion 6b curved upward at the center portion, and a gap G between the floating portion 6b and the bottom surface 4a. It is an intervening form.

  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 ... Core, 2 ... Coil, 3 ... Bobbin, 4 ... Case, 4a ... Bottom surface, 4b ... Side surface, 5 ... Cooler, 5a ... Flow path, 6, 6A, 6B, 6C ... Metal plate, 6a ... Fixed part, 6b ... Floating part, 7 ... Stay, 8 ... Bolt, 10 ... Reactor, G ... Gap, R ... Refrigerant

Claims (1)

A case composed of a bottom surface and a side surface;
A core comprising a coil disposed in a case, and a reactor,
A metal plate provided with a fixed portion and a floating portion is fixed to the inside of the bottom surface of the case via the fixed portion, and in the fixed state of the metal plate, the floating portion is in a state of floating through a gap from the bottom surface,
A reactor in which a core including a coil is placed on a floating portion.

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