JP2015176886A - Attachment structure of reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for preventing adhesion of a heat transfer sheet sandwiched between the coil of a reactor and a plate and the coil from lowering, or preventing the heat transfer sheet from scattering, relating to an attachment structure of a reactor with a coil to a plate.SOLUTION: A reactor 2 is attached to the bottom plate 10 while sandwiching a heat transfer sheet 8. The reactor 2 has coils 3a, 3b of rectangular cross section, and its one flat side face is in contact with the case bottom plate 10 while sandwiching the heat transfer sheet 8. A gap between the reactor 2 and the bottom plate 10 is sealed by a gasket 6, so as to surround the heat transfer sheet 8 exposed from between the coils 3a, 3b and the case bottom plate 10. The gasket 6 reduces the load on the heat transfer sheet 8, and even if the end of the heat transfer sheet 8 is torn off, its fragments are prevented from scattering to the outside.

Description

  The present invention relates to a reactor mounting structure. The reactor is a passive element using a coil.

  The reactor is used for a voltage converter or the like. Specifically, for example, in a voltage converter capable of performing step-up and step-down, a reactor is connected between the middle point of a series circuit of two switching elements and a high potential terminal on the low voltage side. In a power converter with a voltage converter that supplies electric power to a running motor of an electric vehicle, the amount of heat handled is large, and thus the amount of heat generated by the reactor is large. Therefore, in an electric vehicle or the like, a technique may be adopted in which the coil of the reactor is brought into contact with the case of the power converter with the heat transfer sheet interposed therebetween to diffuse heat to the case. The “case” may be provided with a flow path through which the refrigerant passes through the side wall, the bottom plate, or the like. That is, the case may also serve as a cooler.

  Since electric vehicles and the like are used every 10 years, countermeasures against aging are important. When a reactor is attached to the bottom of the case with the heat transfer sheet interposed therebetween, the heat transfer sheet may become thin due to deterioration over time, and the adhesion between the coil and the heat transfer sheet may be reduced. Also, if the heat transfer sheet is tightened tightly with the coil and case so that the adhesion does not deteriorate, the heat transfer sheet becomes brittle due to deterioration over time, and the edges of the heat transfer sheet may collapse and the dust may be scattered in the case There is also. In addition, although the power converter mounted in an electric vehicle receives the vibration of an electric vehicle, the vibration also becomes a cause of tearing the edge of a heat-transfer sheet | seat.

  Therefore, Patent Document 1 proposes a technique in which a recess is provided on the bottom surface of the case, a heat transfer sheet is disposed in the recess, and a reactor is disposed so that a coil is positioned thereon. The depression is the same size as the heat transfer sheet, and the heat transfer sheet abuts on the side surface of the depression. When the reactor is attached, the coil presses the heat transfer sheet in the thickness direction. Due to this compression, the heat transfer sheet tends to spread in the lateral direction (the direction perpendicular to the bottom surface of the dent and the stacking direction of the heat transfer sheet and the coil), but the side surface of the dent restrains the heat transfer sheet. Does not spread. Therefore, the thickness of the heat transfer sheet is not reduced over time, and high-density contact between the heat transfer sheet and the coil is maintained. Moreover, since the heat transfer sheet is housed in the recess, even if the end of the heat transfer sheet is cut off, it is prevented from scattering to various parts of the case.

JP2013-118208A

  The technique of Patent Document 1 needs to form a recess in the case. This specification provides the technique of preventing the fall of the adhesiveness of the heat-transfer sheet | seat and coil which are pinched | interposed between the coil of a reactor, and a case floor surface (plate), or scattering of a heat-transfer sheet | seat, without providing a hollow.

  The technology disclosed in this specification relates to a structure for attaching a reactor to a plate. In the structure, one side of the reactor coil is in contact with the plate with the heat transfer sheet interposed therebetween. Further, the gap between the reactor and the plate is sealed with an elastic material so as to surround the heat transfer sheet exposed from between the coil and the plate. In other words, the stretchable material is a sealing material, typically an O-ring or a gasket. More specifically, the elastic material is a silicon rubber ring. The “plate” represents a member for fixing the reactor, and is typically a side wall or a bottom plate of the case of the power converter.

  According to the above structure, the pressing force between the plate and the reactor is dispersed in the heat transfer sheet and the stretchable material. That is, since the load applied to the heat transfer sheet is reduced, the progress of deterioration of the heat transfer sheet is suppressed. Therefore, a decrease in the adhesion between the coil and the heat transfer sheet due to deterioration is suppressed. Even if the end of the heat transfer sheet is broken, the stretchable material seals the gap between the reactor and the plate, so that broken pieces are not scattered.

  According to the technology disclosed in the present specification, it is possible to prevent deterioration or scattering of the adhesion between the heat transfer sheet and the coil between the reactor coil and the floor surface (plate) without providing a recess in the plate for fixing the reactor. can do. 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 along the II-II line of FIG. It is sectional drawing along the III-III line of FIG.

  A reactor mounting structure of an embodiment will be described with reference to the drawings. In FIG. 1, the top view of the reactor 2 attached on the case bottom board 10 is shown. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. The reactor 2 is a device used for a power converter that supplies power to a traveling motor of an electric vehicle. Reference numeral 10 denotes a bottom plate of the power converter. More specifically, the reactor 2 is a component of a voltage converter circuit that boosts the voltage of the battery. In FIG. 1, parts covered by the resin cover 5 are drawn with broken lines.

  The reactor 2 includes a ring-shaped core 4 that is partially parallel, a resin bobbin 7 that covers the parallel part of the core 4, and coils 3 a and 3 b that are wound around each bobbin, A resin cover 5 in which the core 4, the bobbin 7, and the coils 3a and 3b are molded is provided. The resin cover 5 does not cover all of the coils 3 a and 3 b, but the lower surfaces of the coils 3 a and 3 b are exposed from the resin cover 5. The resin cover 5 is made by putting an assembly of the core 4, the bobbin 7, and the coils 3a and 3b into a mold and injecting molten resin therein.

  Since a large current for driving the traveling motor flows through the reactor 2, the amount of heat generated is large. In order to suppress the temperature rise of the coils 3a and 3b, the reactor 2 is fixed to the case so that one side surface of the coils 3a and 3b is in contact with the bottom plate 10 with the heat transfer sheet 8 interposed therebetween. In addition, the flange is extended from the side surface of the resin cover 5, and the reactor 2 is attached to the case (bottom plate 10) with the bolt 19 through the flange. A bolt fixing projection 10a extends from the bottom plate 10, and the bolt 19 is fixed to a screwing hole provided in the projection 10a.

  As clearly shown in FIG. 3, the cross sections of the coils 3a and 3b are rectangular. In other words, the coils 3a and 3b have a quadrangular prism shape. One flat side surface of the square pillar is in contact with the bottom plate 10 with the heat transfer sheet 8 interposed therebetween. The heat of the coils 3a and 3b is diffused to the bottom plate 10 through the heat transfer sheet 8, thereby suppressing the temperature rise of the coils 3a and 3b. The heat transfer sheet 8 is obtained by mixing, for example, a silicon resin with a large number of small metal pieces that increase thermal conductivity.

  A groove 5a is provided on the bottom surface of the resin cover 5 so as to surround the coils 3a and 3b. The lower surface of the resin cover 5 is a surface facing the bottom plate 10. A gasket 6 is fitted in the groove 5a. The groove 5a faces the bottom plate 10, and the gasket 6 fills the gap between the resin cover 5 and the bottom plate 10 while fitting into the groove 5a. The gasket 6 seals the gap between the reactor 2 and the bottom plate 10 so as to surround the heat transfer sheet 8 exposed from between the coils 3 a and 3 b and the bottom plate 10. In other words, the gasket 6 blocks the space where the heat transfer sheet 8 is located from the external space.

  The gasket 6 is made of, for example, silicon rubber and has stretchability (rebound). As shown in FIGS. 2 and 3, the gasket 6 is pressed against the resin cover 5 and the bottom plate 10, and a portion close to the bottom plate 10 side is deformed.

  The advantages of this gasket 6 will be described. As shown in FIGS. 1 and 2, the reactor 2 is attached so as to be pressed against the bottom plate 10 by four bolts 19. Due to the load, the heat transfer sheet 8 is pressed between the flat one side surface of the coils 3 a and 3 b of the reactor 2 and the bottom plate 10, and the gasket 6 is pressed between the bottom surface of the resin cover 5 and the bottom plate 10. . That is, the force pressing the reactor 2 against the bottom plate 10 is dispersed in the heat transfer sheet 8 and the gasket 6. Therefore, compared with the case where there is no gasket 6, the stress which arises in the heat-transfer sheet 8 resulting from the bolt fixation of the reactor 2 is reduced. Since the stress applied to the heat transfer sheet 8 is reduced, the progress of deterioration of the heat transfer sheet 8 is suppressed. Therefore, high adhesion between the heat transfer sheet 8 and the coils 3a and 3b is ensured over a long period of time.

  The reactor 2 itself is fixed to the bottom plate 10 with a tightening force corresponding to the resultant force of the repulsive force of the heat transfer sheet 8 and the repulsive force of the gasket 6. That is, by arranging the gasket 6, it is possible to both firmly fix the reactor 2 to the bottom plate 10 and reduce the load on the heat transfer sheet 8. In other words, the gasket 6 reduces the load on the heat transfer sheet 8.

  Further, the gasket 6 seals the heat transfer sheet 8 in a space between the reactor 2 and the bottom plate 10. Therefore, even if the end of the heat transfer sheet 8 is shredded and dispersed due to the progress of deterioration or vehicle vibration, the discrete fragments will not move out of the space between the reactor 2 and the bottom plate 10. . That is, the gasket 6 prevents the dust generated from the heat transfer sheet 8 from leaking out of the closed space (the space surrounded by the reactor 2, the bottom plate 10, and the gasket 6). For example, the dust from the heat transfer sheet 8 is prevented from being scattered in the case of the power converter in which the reactor 2 is housed. The above advantages can be obtained without requiring processing such as providing a recess in the bottom plate 10. However, it should be noted that the technique disclosed in this specification does not exclude an aspect in which a recess is provided in the bottom plate 10 and a heat transfer sheet is disposed therein.

  Other advantages of the gasket 6 will be described. The gasket 6 also contributes to vibration suppression of the reactor 2. As a result, the gasket 6 further reduces the influence of the vehicle vibration on the heat transfer sheet 8. Further, since the gasket 6 surrounds the heat transfer sheet 8 between the reactor 2 and the bottom plate 10, the heat transfer sheet 8 is also prevented from shifting. In other words, the gasket 6 regulates the position of the heat transfer sheet 8 so that the heat transfer sheet 8 always remains in contact with the coils 3a and 3b. This advantage prevents the heat transfer efficiency from the coils 3a, 3b to the bottom plate 10 via the heat transfer sheet 8 from being lowered.

  Points to be noted regarding the technology described in the embodiments will be described. The bottom plate 10 corresponds to an example of a plate in the claims. The gasket 6 corresponds to an example of the stretchable material described in the claims. An O-ring may be used instead of the gasket 6. The gasket 6 need not be silicon rubber. The gasket 6 may be made of resin, for example. The reactor 2 of the embodiment has the ring-shaped core 5 and the two coils 3a and 3b. However, the technology disclosed in the present specification has other shapes, for example, a linear core and one coil. It is also suitable to apply to the reactor which has.

  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: Reactor 3a, 3b: Coil 4: Core 5: Resin cover 5a: Groove 6: Gasket (expandable material)
7: Bobbin 8: Heat transfer sheet 10: Case bottom plate (plate)
10a: Bolt fixing protrusion 19: Bolt

Claims (1)

It is a structure to attach the reactor to the plate,
One side of the coil of the reactor is in contact with the plate across the heat transfer sheet,
A reactor mounting structure, wherein a gap between the reactor and the plate is sealed with an elastic material so as to surround the heat transfer sheet exposed from between the coil and the plate.

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