JP2015176989A - reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for enhancing heat dissipation by reducing the gap between the inner side face of a case and the coil side face while ensuring the creepage distance of the coil and the case in a reactor.SOLUTION: In a reactor 30, a coil 41 is housed in a metal case 2, and the gap between the inner side face 21b of the case and the coil 41 is filled with an insulating potting material 5. Upper part of the coil 41 is exposed from the upper surface of the potting material 5. In the inner side face 21b of the case facing the side face 41b of the coil, a step is provided so that the inner side face on the upper side of the step surface is separated farther than the inner side face on the lower side, from the side face 41b of the coil. The gap is filled with the potting material 5 above the step surface.

Description

  The present invention relates to a reactor. A reactor is a passive element using a coil, and is sometimes called an “inductor”.

  The reactor is a passive element used for power factor improvement, harmonic current suppression (direct current smoothing), and the like. The reactor may also be used in a device that boosts a DC voltage. The reactor includes a magnetic core and a coil wound around the core. Some reactors have a bobbin that holds a coil. The reactor may be covered with a resin for the purpose of insulation and protection from physical contact with other devices.

  In recent years, hybrid cars and electric cars have been put into full-scale use, and the number of them used is rapidly increasing. Since hybrid vehicles and electric vehicles use a motor as a driving force, a reactor is provided in the drive circuit. In these automobiles, a large capacity reactor (a motor with high power consumption) is driven, and thus a large capacity reactor is required. The main component of the reactor is a coil, and a force that vibrates the reactor itself is generated by an alternating magnetic field generated when an alternating current is passed through the coil. In a hybrid vehicle or an electric vehicle, a large current flows through the reactor, so that the vibration force is increased. It is necessary to suppress the vibration of the coil against the force causing the self-excited vibration.

  One technique for improving the vibration resistance of electronic components such as reactors is a technique called potting. Examples thereof are disclosed in Patent Documents 1-3. Potting is a technology in which an electronic component such as a reactor is placed in the case, and then a fluid insulator such as silicon resin (an insulator that solidifies later) is injected into the case to fill all or part of the electronic component. It is. Since the heat of the electronic component is diffused through the potting material, the potting material also contributes to cooling of the electronic component.

  The reactors of Patent Documents 1-3 all have the following common configuration. The reactor is obtained by winding a coil around two parallel portions of a partially parallel annular core. The two coils are arranged in the case so that the axes thereof are parallel to each other in the horizontal plane, and a potting material is filled in the gap between the lower side of the coil and the inner surface of the case so that the upper part of the coil is exposed. ing.

JP 2013-021217 A JP 2013-038324 A JP 2010-272584 A

  The case that houses the coil is often made of a metal with high thermal conductivity, typically aluminum. On the other hand, the potting material is not as thermally conductive as the metal case. Therefore, it is advantageous in terms of heat dissipation of the coil that the gap between the inner surface of the case and the coil is made as narrow as possible to reduce the thickness of the potting material layer. However, if the inner surface of the case and the side surface of the coil are close, the creepage distance between the coil and the case via the surface of the potting material will be shortened, and current will flow between the coil and the case along the surface of the potting material. There is a risk that.

  This specification was created in view of the above problems. The present specification provides a technique for reducing the clearance between the case inner side surface and the coil side surface in a reactor to improve heat dissipation and ensuring the creepage distance between the coil and the case.

  The reactor disclosed in this specification has a structure in which a coil is accommodated in a metal case, and an insulating potting material is filled between the case inner surface and the coil. The upper part of the coil is exposed from the upper surface of the potting material. And the novel reactor which this specification discloses is provided with the level | step difference in the inner surface which is an inner surface of a case and opposes a coil side surface. In this step, the inner side surface above the step surface is farther from the coil side surface than the inner side surface below the step surface. Then, the potting material is filled up to above the step surface. That is, the upper surface of the potting material is located above the step surface. Here, the “step surface” means a boundary between the lower side of the case inner surface that is close to the coil and the upper side of the case inner surface that is far from the coil.

  In the reactor having the above structure, the gap between the inner side surface and the coil side surface can be reduced below the step surface on the inner side surface of the case, and heat dissipation can be improved. On the other hand, since the distance (creeping distance) between the inner side surface and the coil side surface can be increased along the upper surface of the potting material above the step surface, high insulation can be ensured.

  According to the technology disclosed in this specification, with respect to a reactor in which a space between the case inner side surface and the coil side surface is filled with a potting material, the clearance between the case inner side surface and the coil side surface is reduced and heat dissipation is improved. In addition, it is possible to achieve a balance between the creepage distance between the coil and the case. Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a top view of the reactor of an Example. It is sectional drawing in the II-II line of FIG. It is sectional drawing in the III-III line of FIG. FIG. 4 is an enlarged view of a range surrounded by a broken line IV in FIG. 3.

  A reactor according to an embodiment will be described with reference to the drawings. FIG. 1 is a plan view of a reactor 30 of the embodiment. 2 is a cross-sectional view taken along line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. Reactor 30 is configured by attaching reactor body 3 to case 2 and filling potting material 5 between reactor body 3 and case 2. Reactor 30 is a component of a voltage converter circuit built in a power conversion device that is mounted on an electric vehicle and boosts the DC voltage of the battery, further converts it to AC and supplies it to the motor. Case 2 is a part of the casing of the power converter. Since a large current flows through the reactor 30, heat is generated. The heat diffuses into the case 2 through the potting material 5. The case 2 also has a function as a cooling member for absorbing the heat. In the figure, only a part of case 2 is shown. In addition, a coordinate system is shown in the figure, and in this specification, the configuration of the embodiment will be described using the coordinate system in a timely manner.

  The reactor main body 3 is configured by a bobbin 7 covering each of the parallel portions of the annular core 6 that is partially parallel, and coils 41 and 42 are attached to the bobbin 7. The bobbin 7 includes a pair of cylindrical core covers 81 and 82 and flanges 91 and 92. The pair of core covers 81 and 82 are arranged in parallel, and both ends thereof are connected by flanges 91 and 92. The bobbin 7 is made of resin. Parallel portions of the core 6 pass through the hollow portions of the cylindrical core covers 81 and 82.

  As shown in FIG. 3, the core 6 has a quadrangular cross-sectional shape orthogonal to the annular circumferential direction. The core 6 is made of a magnetic material. For example, the core 6 is made by solidifying a powder containing magnetic particles by a processing method such as sintering or compression molding.

  The coils 41 and 42 are configured by winding a rectangular wire 12 made of copper around the core covers 81 and 82 in an edgewise manner. That is, in the coils 41 and 42, the rectangular wire 12 is wound so that the wide side surface of the rectangular wire 12 is laminated in the direction of the winding axis of the coil (hereinafter referred to as the winding axis direction). The width (line width) of the wide side surface of the flat wire 12 is appropriately set depending on the electrical characteristics or specifications of the reactor 30. In this embodiment, the coils 41 and 42 are wound so as to form a rectangular shape (substantially square shape) when viewed from the winding axis direction (X-axis direction). The coils 41 and 42 are made of a single rectangular wire 12 and are electrically connected in series. The wound coils 41 and 42 are arranged in parallel so as to be aligned in the radial direction of the winding. Note that the ends of the rectangular wires 12 constituting the coils 41 and 42 extend toward the outside of the reactor 30. Note that in FIGS. 2 and 3, the end of the rectangular wire 12 is omitted.

  Case 2 is made of a metal having high thermal conductivity, specifically, aluminum. Heat generated from the coils 41 and 42 of the reactor body 3 is diffused through the potting material 5 filled between the reactor body 3 and the case 2 and absorbed by the case 2. As shown in FIGS. 2 and 3, the reactor main body 3 is accommodated in the inner surface 21 of the case 2. The lower side which is a part of the two coils 41 and 42 is located inside the inner surface 21. The side surface 41 b of the coil 41 (hereinafter referred to as the coil side surface 41 b) and the side surface 42 b of the coil 42 (hereinafter referred to as the coil side surface 42 b) are opposed to the inner side surface 21 b of the inner surface 21. The coils 41 and 42 are arranged so that the winding axis is parallel to the bottom surface 21 a of the inner surface 21. As shown in FIG. 1, the reactor main body 3 is attached to the case 2 by attachment plates 16 provided on both sides of the coil arrangement direction (Y-axis direction) of the flanges 91 and 92 on the four sides of the bobbin 7. . The mounting plate 16 is fastened to the case 2 by bolts 17.

  A potting material 5 is filled between the inner surface 21 of the case 2 and the reactor body 3. The potting material 5 is a fluid insulator made of silicon resin. The potting material 5 is solidified after being filled. The potting material 5 improves the vibration resistance of the reactor body 3. As shown in FIG. 3, there is a gap between the bottom surface 21 a of the inner surface 21 of the case 2 and the lower surface 41 a of the coil 41 (the lower surface 42 a of the coil 42), and the potting material 5 is filled in this gap. There is also a gap between the inner side surface 21b of the inner surface 21 and the coil side surface 41b (coil side surface 42b), and the potting material 5 is also filled in this gap. Further, the upper surface 5 a of the potting material 5 is located inside the inner surface 21 of the case 2, and the upper portions of the coils 41 and 42 are exposed from the upper surface 5 a of the potting material 5.

  With reference to FIG. 4, the level | step difference 22 provided in case 2 is demonstrated. FIG. 4 is an enlarged view of a range surrounded by a broken line IV in FIG. As shown in FIG. 4, a step 22 is provided on the inner side surface 21b of the case 2 facing the coil side surface 41b. The step 22 has a step surface 22c located above the bottom surface 21a of the case 2, and the step surface 22c is parallel to the bottom surface 21a. As shown in FIG. 4, in the inner side surface 21b, the distance L2 between the inner side surface 22b above the step surface 22c and the coil side surface 41b is equal to the inner side surface 22a and the coil side surface 41b below the step surface 22c. Is greater than the distance L1. That is, the inner side surface 22b above the step surface 22c is farther from the coil side surface 41b than the inner side surface 22a below the step surface 22c. In other words, the step 22 (step surface 22a) means a boundary between the lower inner surface 22a, which is close to the coil side surface 41b, and the upper inner surface 22b, which is far from the coil side surface 41b. Further, as shown in FIG. 4, the potting material 5 filled between the inner surface 21b of the case 2 and the coil 41 is filled up to a level above the step surface 22c. That is, the upper surface 5a of the potting material 5 is located above the step surface 22c (Z-axis positive direction). A similar step is also provided on the inner side surface 21b facing the side surface 42b of the coil 42.

  The effect of the embodiment will be described. The closer the distance between the inner surface of the case and the side surface of the coil, the more advantageous in terms of heat dissipation. However, when the distance between the inner surface and the side surface of the coil becomes shorter, the creepage distance through the upper surface of the potting material becomes shorter. That is, shortening the distance between the inner surface and the side surface of the coil has a trade-off relationship with ensuring insulation performance. In the embodiment, by providing the step 22, on the inner surface 21b, the distance L2 between the inner surface 22b above the step surface 22c and the coil side surface 41b is between the inner surface 22a and the coil side surface 41b below the step surface 22c. It is larger than the distance L1. By increasing the distance L2, the creepage distance through the upper surface 5a of the potting material 5 located between the inner side surface 22b and the coil side surface 41b can be increased, and the insulation performance can be ensured. On the other hand, the distance L1 can be determined independently of the distance L2. By making the distance L1 smaller than the distance L2, the heat dissipation performance can be enhanced. Note that reducing the distance L3 between the lower surface 41a of the coil 41 and the bottom surface 21a of the inner surface 21 contributes to improving the heat dissipation performance of the reactor 30. Preferably, the heat dissipation performance is improved by reducing both the distance L2 and the distance L3. In this way, it is possible to increase both the creepage distance through the upper surface 5a of the potting material 5 and ensure insulation and to improve the heat dissipation performance of the reactor 30.

  Further, when the reactor 30 is assembled, the potting material 5 is a fluid liquid material. If the amount of the potting material 5 to be filled at the time of assembly varies, the liquid level of the potting material 5 varies. If the liquid surface height of the potting material 5 varies, the upper surface 5a after the potting material 5 solidifies may vary, and the heat dissipation performance of the reactor 30 may vary. In the embodiment, by providing the step 22, the gap between the core side surfaces 41b and 42b where the upper surface 5a of the potting material 5 is located and the inner side surface 21b is increased. At the time of assembly, the liquid level of the potting material 5 is located in this gap. If the gap is increased, the variation in the liquid level due to the variation in the amount of the potting material to be filled can be suppressed to a small level. That is, by providing the step 22, variation in the liquid level height of the potting material 5 can be suppressed small.

  Hereinafter, points to be noted regarding the technology shown in the embodiments will be described. Upper portions of the coils 41 and 42 exposed from the potting material 5 (portions above the upper surface of the case 2 of the coils 41 and 42) may be covered with a resin cover. This cover may be large enough to cover the entire reactor body 3.

  In the inner surface 21b of the case 2, the inner surface 22a below the step surface 22c may be curved along the shape of the coil side surface 41b. The distance between the coil side surface and the inner side surface can be kept constant, which can contribute to the improvement of the heat dissipation performance of the reactor 30.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Case 3: Reactor body 5: Potting material 6: Core 7: Bobbin 12: Flat wire 16: Mounting plate 17: Bolt 30: Reactor 21: Inner surface 21b: Inner side surface 22: Step 22c: Step surfaces 22a, 22b: Inner Side surface (below and above the step surface)
41, 42: Coil 41b, 42b: Coil side surface

Claims (1)

A coil is housed in a metal case, and is a reactor filled with an insulating potting material between the inner surface of the case and the coil,
The upper part of the coil is exposed from the upper surface of the potting material,
On the inner side surface of the case that faces the side surface of the coil, a step is provided in which the inner side surface above the step surface is farther from the side surface of the coil than the inner side surface below the step surface. And
The reactor, wherein the potting material is filled to a level above the step surface.

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