JP2019204930A - Electrical machine - Google Patents

Abstract

To provide a technique for mitigating stress generated in a board and resulting from the difference of the coefficient of linear thermal expansion of a case and a board.SOLUTION: An electrical machine comprises a board to which an electronic component has been attached, a case to which the board is fixed, and a cover fixed to the case. On the face of the case facing the board, a pressing hub abutting on the board in the outer peripheral region of the board is provided, and a coupling hub abutting on the board on the inside of the outer peripheral region is provided. The board is fixed to the coupling hub by means of a screw penetrating the board, and clamped by the pressing hub and the cover. According to the structure mentioned above, the outer peripheral region of the board is clamped by the cover and the pressing hub and fixed. Since the outer peripheral region of the board where deformation volume is large when cold can slide in the surface direction when cold, stress generated in the board and resulting from the difference of the coefficient of linear thermal expansion between the board and the case can be mitigated.SELECTED DRAWING: Figure 3

Description

  The technology disclosed in this specification relates to an electronic apparatus in which a substrate on which an electronic component is attached is fixed to a case.

  In electrical equipment, a substrate on which electronic components are attached is attached to a case. Usually, the linear expansion coefficients of the substrate and the case are different. For this reason, if the case and the substrate are firmly fixed with a plurality of screws, high stress may be generated on the substrate due to the difference in the coefficient of linear expansion. Japanese Patent Application Laid-Open No. H10-228561 discloses a technique for relieving stress generated in a substrate due to a difference in linear expansion coefficient.

  Patent Document 1 discloses an inverter in which a substrate is fixed to a metal plate inside a case with a male screw. The metal plate is provided with a first boss at positions corresponding to the four corners of the substrate, and a second boss is provided inside a rectangle connecting the four first bosses. The substrate is fixed to each of the first boss and the second boss with a male screw via a rubber washer. When the rubber washer that is an elastic body is deformed, the stress generated in the substrate due to the difference in linear expansion coefficient between the metal plate and the substrate is relieved. Patent Document 1 discloses that a rubber washer may not be sandwiched between one second boss on the inside of a rectangle and the substrate, and may be firmly fixed with a male screw.

JP 2014-240675A

  This specification provides a technique for reducing stress generated in a substrate due to a difference in linear expansion coefficient between a case and the substrate more cost-effectively than in the past.

  An electronic device disclosed in the present specification includes a substrate to which electronic components are attached, a case to which the substrate is fixed, and a cover that is fixed to the case. A pressing boss that contacts the substrate in the outer peripheral region of the substrate is provided on the surface of the case facing the substrate, and a fastening boss that contacts the substrate is provided inside the outer peripheral region. The substrate is fixed to the fastening boss with a screw that penetrates the substrate, and is sandwiched between the pressing boss and the cover. According to said structure, the outer peripheral area | region of a board | substrate is clamped and fixed by the cover and the pressing boss | hub. As a result, the outer peripheral region of the substrate having a large deformation amount at the time of cooling can slide in the surface direction at the time of cooling, so that it is caused by the difference in the coefficient of linear expansion between the substrate and the case without using a rubber washer or the like. The stress generated in the substrate can be relaxed.

  The end of the cover may be thicker than the center, and the cover may be configured so that the substrate is sandwiched between the end of the cover and the pressing boss while being fixed to the case at the end. . Rather than increasing the thickness of the entire cover, increasing the thickness only at the edges can increase the rigidity of the cover where the substrate is fixed, while suppressing an increase in the weight of the entire cover. For example, when the cover is made of a metal plate, the end portion may be thicker than the center by folding back the end of the metal plate.

  The width of the fastening boss root in the cross section along the radial direction from the substrate center of the fastening boss may be shorter than the width of the fastening boss root in the cross section perpendicular to the radial direction. The width of the pressing boss root in the cross section along the radial direction of the pressing boss may be shorter than the width of the pressing boss root in the cross section in the direction orthogonal to the radial direction. With this feature, the rigidity of the fastening boss / pressing boss in the substrate radial direction can be made lower than the rigidity in the direction crossing the radial direction. The difference in the coefficient of linear expansion between the substrate and the case appears remarkably in the radial deviation between the substrate and the case. That is, the stress generated in the substrate due to the difference in linear expansion coefficient becomes significant in the radial direction. By reducing the rigidity in the radial direction while maintaining the rigidity in the direction intersecting the radial direction of the fastening boss / pressing boss, the stress generated in the substrate can be alleviated while suppressing a decrease in strength.

  Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a perspective view of the electric equipment of 1st Example. It is a top view of the case of the electric equipment of 1st Example. It is sectional drawing along the III-III line in FIG. It is sectional drawing of the electric equipment of 2nd Example. It is a top view of the case of the electric equipment of 3rd Example. It is sectional drawing along the VI-VI line in FIG. It is sectional drawing along the VII-VII line in FIG. It is a top view of the case of the electric equipment of 4th Example. It is sectional drawing along the IX-IX line in FIG. It is sectional drawing along the XX line in FIG.

  (First Embodiment) An electric apparatus 1 according to a first embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the electric device 1, and FIG. 2 is a plan view of the case 13. The electric device 1 is a power control device mounted on an electric vehicle. The electric device 1 is a device that converts electric power of a vehicle-mounted battery into driving power of a traveling motor.

  The electrical device 1 includes a cover 11, a substrate 12, a case 13, screws 14 that fix the substrate 12 to the case 13, and screws 15 that fix the cover 11 to the case 13. The case 13 is provided with an intermediate partition plate 133 supported on the outer wall. In FIG. 1, the inner partition plate 133 of the case 13 is drawn with a solid line and the outer wall part 134 is drawn with a virtual line so that the fixing portion of the substrate 12 in the case 13 can be seen well. In addition to the substrate 12, the case 13 of the electrical device 1 houses various components such as a power module that is a main component for power conversion, but these are not shown. In FIG. 2, the cover 11, the substrate 12, the screw 14, and the screw 15 are not drawn so that the case 13 can be clearly seen, and only the case 13 is illustrated in a plan view.

  Various electronic components are attached to the substrate 12. Electronic components are mounted on the surface of the substrate 12 and printed wiring for electrically connecting the electronic components is drawn, but the illustration of the electronic components and the printed wiring is omitted. Various electronic components constitute a control circuit for controlling the power module. The substrate 12 (control circuit) receives sensor data from a current sensor (not shown) disposed under the case 13, and controls the power module based on the sensor data.

  The substrate 12 is fixed to the partition plate 133 of the case 13 with a plurality of screws 14. The substrate 12 is made of resin. The case 13 is made of a material (for example, aluminum) having a linear expansion coefficient different from that of the resin. For this reason, if the substrate 12 is firmly fixed to the case 13, a large stress is generated in the substrate 12 when thermally expanded, and the substrate 12 may be damaged. In the electric device 1, the substrate 12 is fixed to the case 13 so that the stress generated in the substrate due to the difference in linear expansion coefficient between the substrate 12 and the case 13 is low.

  The substrate 12 is attached to the partition plate 133 of the case 13. A pressing boss 132 that contacts the substrate 12 in the outer peripheral region of the substrate 12 is provided on the surface of the case 13 that faces the substrate 12 (that is, the partition plate 133). A fastening boss 131 is provided in contact with the boss 12. Here, the outer peripheral area refers to an area that goes around the outer periphery of the substrate with a predetermined width (for example, 30 mm).

  FIG. 3 is a cross-sectional view taken along line III-III in FIG. In other words, FIG. 3 shows a cross section of the fixing part of the cover 11, the substrate 12, and the case 13 of the first embodiment. Inside the outer peripheral region of the substrate 12, the substrate 12 is firmly fixed by a fastening boss 131 of the intermediate partition plate 133 (case 13) and screws 14 that penetrate the substrate 12. For this reason, the stress by the deformation | transformation at the time of the cold concerning the board | substrate 12 becomes large as the outer peripheral area | region of the board | substrate 12 is approached.

  In the outer peripheral region of the substrate 12, the substrate 12 is fixed by being sandwiched between the pressing boss 132 of the case 13 and the cover 11. Therefore, the outer peripheral region of the substrate 12 can slide in the surface direction during cooling, and the stress generated in the substrate due to the difference in the linear expansion coefficient between the substrate 12 and the case 13 can be relieved. Further, outside the outer peripheral region of the substrate 12, the case 13 and the cover 11 are fixed to the outer wall portion 134 of the case 13 by screws 15 penetrating the cover 11, so that vehicle vibration is transmitted to the outer peripheral region of the substrate 12. Can be suppressed. Further, a sealing material, rubber, or the like may be sandwiched between contact portions of the substrate 12 and the cover 11. Thereby, the force with which the cover 11 presses the substrate 12 can be made uniform.

  (Second Embodiment) An electrical apparatus 1a according to a second embodiment will be described with reference to FIG. When the cover 11a is a metal plate, for example, the thickness of the end of the cover 11a is increased by folding the end of the cover 11a. Thereby, the rigidity of the cover of the part which fixes a board | substrate can be improved, suppressing the weight increase of the whole cover 11a.

  (Third Embodiment) An electric apparatus 1b according to a third embodiment will be described with reference to FIGS. FIG. 5 shows a plan view of the case 13b. Although the substrate is not shown in FIG. 5, the substrate is attached so as to face the partition plate 133b. The case 13 in FIG. 2 differs from the case 13 in the arrangement of the fastening bosses. However, like the case 13 in FIG. 2, the board is firmly fixed by the fastening bosses 131b of the case 13b and screws passing through the board. It is fixed. For this reason, the amount of deformation during cooling increases as the distance from the center of the substrate increases in the radial direction. Therefore, the stress generated in the substrate due to the difference in linear expansion coefficient becomes significant in the radial direction.

  6 shows a cross section taken along line VI-VI in FIG. 5, and FIG. 7 shows a cross section taken along line VII-VII in FIG. FIG. 6 shows a cross section along the radial direction from the substrate center of the fastening boss 131b. FIG. 7 shows a cross section in a direction crossing the radiation direction. The root width d1 (that is, the root width in the radial direction) of the fastening boss 131b in FIG. 6 is shorter than the root width d2 in FIG. 7 (that is, the width of the root in the direction intersecting the radial direction). Although illustration is omitted, similarly, the width of the base of the pressing boss 132b in the cross section along the radial direction of the pressing boss 132b is shorter than the width of the base of the pressing boss 132 in the cross section perpendicular to the radial direction.

  As a result, the rigidity of the fastening boss 131b / pressing boss 132b in the substrate radial direction can be made lower than the rigidity in the direction crossing the radial direction. The fastening boss 131b / pressing boss 132b is easily deformed in the radial direction. Therefore, the stress generated in the substrate can be relaxed while suppressing the strength reduction of the case 13b.

  (Fourth Embodiment) An electric apparatus 1c according to a fourth embodiment will be described with reference to FIGS. FIG. 8 shows a plan view of the case 13c. Although the substrate is not shown in FIG. 8, the substrate is attached so as to face the partition plate 133c. Since the arrangement of the fastening bosses is the same as that of the case 13b in FIG. 5, the stress generated in the substrate due to the difference in the coefficient of linear expansion is significant in the radial direction, as in the electric device 1b of the third embodiment.

  A rib 135 is provided in the middle partition 133 c, and the fastening boss 131 c is formed integrally with the rib 135. The rib 135 extends in a direction intersecting the radial direction from the center of the substrate. 9 shows a cross section taken along line IX-IX in FIG. 8, and FIG. 10 shows a cross section taken along line XX in FIG. FIG. 9 shows a cross section along the radial direction from the substrate center of the fastening boss 131c, and FIG. 10 shows a cross section in a direction intersecting the radial direction.

  FIG. 9 shows a root width d3 of the fastening boss 131c in a cross section along the radial direction from the substrate center of the fastening boss 131c. Further, the fastening boss 131 c is formed integrally with the rib 135. The ribs 135 are provided on the partition plate 133c of the case 13c. Thereby, the base width of the fastening boss 131c in the direction intersecting the radial direction corresponds to the length of the rib 135 in the longitudinal direction. Accordingly, also in the electric apparatus 1c of the embodiment, the base width d3 of the fastening boss 131c in the cross section along the radial direction from the substrate center of the fastening boss 131c is the fastening boss 131c in the cross section perpendicular to the radial direction. Shorter than the width of the base (the length of the rib 135 in the longitudinal direction). Therefore, similarly to the electric device 1b of the third embodiment, the electric device 1c of the fourth embodiment can make the rigidity of the fastening boss 131c in the substrate radial direction lower than the rigidity in the direction crossing the radial direction. Therefore, the fastening boss 131c of the case 13c is easily deformed in the radial direction due to the stress generated in the substrate due to the difference in the linear expansion coefficient. Therefore, the stress generated in the substrate can be relaxed while improving the strength of the case 13c.

  Points to be noted regarding the technology described in the embodiments will be described. The shape and arrangement of the fastening boss / pressing boss correspond to an example of the technique disclosed in this specification. The shape and arrangement of the fastening boss / pressing boss may be changed depending on the outer shape of the electronic device and the relationship with peripheral components such as a current sensor.

  The technology disclosed in the present specification may be applied to electric devices other than the power converter.

  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.

1, 1a, 1b, 1c: Electronic device 11, 11a: Cover 12: Substrate 13, 13b, 13c: Case 14, 15: Screw 131, 131b, 131c: Fastening boss 132, 132b: Pushing boss

Claims (3)

A board on which electronic components are mounted;
A case where the substrate is fixed;
A cover fixed to the case so as to cover the substrate;
With
A pressing boss that contacts the substrate in the outer peripheral region of the substrate is provided on a surface of the case facing the substrate, and a fastening boss that contacts the substrate is provided inside the outer peripheral region. ,
The board is fixed to the fastening boss with a screw that penetrates the board, and is sandwiched between the pressing boss and the cover.   The end of the cover is thicker than the center, the cover is fixed to the case at the end, and the substrate is sandwiched between the end and the pressing boss. 1. The electronic device according to 1. The width of the fastening boss root in the cross section along the radial direction from the substrate center of the fastening boss is shorter than the width of the fastening boss root in the cross section perpendicular to the radial direction,
3. The electron according to claim 1, wherein a width of the pressing boss root in a cross section along the radial direction of the pressing boss is shorter than a width of the pressing boss root in a cross section orthogonal to the radial direction. machine.

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