JP5955814B2 - Fastening structure of control board to metal case of in-vehicle power control unit - Google Patents

Description

  The present invention relates to a fastening structure for fastening a control board to a metal case of a power control unit (hereinafter referred to as “PCU”) directly mounted on a vehicle-mounted transaxle.

  Electric vehicles such as hybrid cars and electric cars have become widespread. Such an electric vehicle is equipped with a power control unit (hereinafter referred to as “PCU”) incorporating an inverter, a step-up / down converter, and the like for controlling the power supplied to the motor and the power generated by the generator. The PCU case normally houses electronic components that constitute an inverter, a step-up / down converter, and the like, for example, a reactor, a capacitor, a switching element, a control board that controls driving of the switching element, and the like.

  In recent years, it has been proposed in part to attach this PCU directly to the upper part or side part of a transaxle (hereinafter referred to as “T / A”) case (for example, Patent Document 1). T / A is a unit in which a motor generator, a transmission gear group, and the like are accommodated in a T / A case.

  Since the T / A vibrates as the motor generator or the like is driven, when the PCU is directly mounted on the T / A case, both the level and frequency of vibration applied to the PCU increase. Therefore, when the PCU is directly mounted on the T / A case, it is necessary to improve the rigidity of the PCU case as a countermeasure against vibration. However, conventional PCU cases are often made of resin, and in order to improve rigidity, it is necessary to increase the thickness of the case or add ribs. Had a problem. In addition, since resin is non-conductive and has low thermal conductivity, additional components such as bus bars and cercon sheets are required for GND connection and heat dissipation of the control board. The problem of increase was also invited.

  Therefore, it is conceivable to use a case made of a metal having conductivity and high rigidity and heat conductivity as the PCU case. If a metal case is used, the rigidity can be improved without increasing the size of the PCU case. Also, if the control board is fastened at multiple points directly to the inner surface of the metal case, and GND connection and heat dissipation are performed on the fastening seating surface, parts such as bus bars and cercon seats can be omitted, and an increase in cost and size can be prevented. .

JP2013-51848A JP 2001-332878 A

  However, when the control board is directly fastened to the metal PCU case at multiple points, there is a possibility that stress is generated on the control board with a temperature change. That is, the control board is usually configured by soldering circuit elements on a printed board in which a circuit pattern is formed of copper foil on an epoxy resin plate containing glass fibers. The linear expansion coefficient differs between this printed circuit board and the metal constituting the PCU case. For this reason, the printed circuit board cannot follow the expansion and contraction of the metal case caused by the temperature change, and surface stress acts on the printed circuit board. This stress action may cause fatigue of the printed circuit board or the circuit pattern, or may crack the soldered portion of the circuit element mounted on the printed circuit board.

  Patent Document 2 discloses a screw tightening structure for an electronic device in which a fastened member (board or the like) on which an electronic component is mounted is screwed and fastened to a female screw formed in a housing (case) with a screw. ing. In this Patent Document 2, the screw is a stepped screw having a head, a screwless portion having a diameter larger than that of the head, and a male screw, and between the screw head and the housing, An O-ring or the like is arranged. However, Patent Document 2 is not a technique for fastening the control board to the PCU case directly mounted on the T / A, and has not been sufficiently studied on countermeasures against vibration caused by the T / A.

  Therefore, the present invention provides a fastening structure for fastening a control board to a metal case of a PCU that is directly mounted on a T / A, and capable of suitably fastening the control board while reducing the influence of vibration. The purpose is to do.

  The fastening structure of the present invention is a fastening structure for fastening a control board in a metal case of a power control unit mounted directly on a vehicle-mounted transaxle, and a cylindrical portion provided on an inner surface of the metal case; A nut having a flange portion at the proximal end, the nut being accommodated in the tubular portion so that the flange portion contacts the bottom surface of the tubular portion, and an elastic ring made of an elastic material, the flange An elastic ring disposed on the portion and packed between the outer peripheral surface of the nut and the inner peripheral surface of the cylindrical portion, and the tip of the cylindrical portion is bent inward, or the upper end opening of the cylindrical portion A caulking lid that is formed by caulking a plate material to the caulking lid that presses the flange portion against the bottom surface of the cylindrical portion via the elastic ring, and an attachment hole formed in the control board, Threaded onto the nut And bolts that, characterized in that it comprises a.

  In a preferred aspect, the control board is placed on a seat surface which is a tip surface of the nut. In another preferred embodiment, a groove serving as a rotational resistance of the nut with respect to the control board is formed in a seating surface that is a tip surface of the nut.

  Another fastening structure according to the present invention is a fastening structure for fastening a control board in a metal case of a power control unit mounted directly on a vehicle-mounted transaxle, and a cylinder provided on an inner surface of the metal case. A bolt having a flange portion at its proximal end, a bolt accommodated in the cylindrical portion so that the flange portion contacts the bottom surface of the cylindrical portion, and an elastic ring made of an elastic material. And an elastic ring disposed on the flange portion and packed between the outer peripheral surface of the bolt and the inner peripheral surface of the cylindrical portion, and the tip of the cylindrical portion is bent inward, or the cylindrical shape A caulking lid formed by caulking a plate material at an upper end opening of the portion, wherein the caulking lid presses the flange portion against the bottom surface of the cylindrical portion via the elastic ring, and an attachment hole formed in the control board. The above-mentioned bo Characterized in that it comprises a nut screwed with the male screw of the bets, the.

  According to the present invention, since the nut is pressed against the bottom surface of the cylindrical portion via the elastic ring, the control board and the metal case fastened to the nut can move in the plane direction with each other. The difference in linear expansion coefficient can be absorbed. The elastic ring also absorbs vertical vibrations transmitted to the metal case. As a result, the control board can be suitably fastened to the metal case while reducing the influence of vibration.

It is a figure which shows PCU directly mounted in T / A. It is a figure which shows the fastening structure which concerns on this embodiment. It is a figure which shows the fastening location of a control board. It is a figure explaining the fastening structure and rigid fixation of this embodiment. 4 is a perspective view of a nut accommodated in an insertion hole 16. FIG. It is a figure which shows the other example of a fastening structure. 4 is a perspective view of a nut accommodated in an insertion hole 16. FIG. It is a figure which shows the other example of a fastening structure. It is a figure which shows the other example of a fastening structure.

  Hereinafter, the fastening structure of the control board 34 which is embodiment of this invention is demonstrated with reference to drawings. First, a power control unit (PCU) 10 provided with a control board 34 will be briefly described with reference to FIG. FIG. 1 is a diagram illustrating an installation state of the PCU 10 in an electric vehicle.

  The PCU 10 is a unit mounted on an electric vehicle such as a hybrid vehicle or an electric vehicle, and includes an inverter, a step-up / down converter, and the like that control electric power supplied to an in-vehicle motor generator or electric power generated by the motor generator. Unit. In this embodiment, the PCU 10 is directly mounted on a case (T / A case 102) of a transaxle (T / A) 100.

  The T / A 100 includes two motor generators MG1 and MG2 and a transmission TM that transmits the output of a power source (motor or engine) to the axle. Motor generator MG and transmission TM are housed in T / A case 102 and installed in the engine compartment. The PCU 10 is directly attached to the upper surface of the T / A case 102 as shown in FIG.

  The PCU 10 has a PCU case 12 made of a metal such as aluminum. Inside the PCU 10 is an electronic component that constitutes an inverter or a step-up / down converter, such as a reactor, a capacitor, a switching element, and the switching element. A control board 34 and the like to be controlled are accommodated. Among these, the installation technology of the reactor, the capacitor, and the switching element is a well-known publicly known technology, and thus description thereof is omitted here. Below, the installation technique of the control board 34 is explained in detail.

  FIG. 2 is a view showing a fastening structure of the control board 34. FIG. 3 is a view showing a fastening portion (position of the mounting hole 40) of the control board 34. As shown in FIG. In FIG. 3, illustration of various circuit elements mounted on the control board 34 is omitted.

  The control board 34 is bolted to the inner surface of the PCU case 12 at multiple points. The structure at each fastening point is as shown in FIG. That is, in the PCU case 12, a substantially cylindrical tubular portion 14 is formed to project at a position corresponding to the fastening location. An insertion hole 16 extending in the axial direction (case thickness direction) is formed at the center of the cylindrical portion 14. In addition, in this embodiment, although the cylindrical part 14 is united with the PCU case 12, both may be comprised as a different body. Therefore, the cylindrical portion 14 formed separately from the PCU case 12 may be fixed to the PCU case 12 by bonding or screwing. In this case, it is desirable that the cylindrical portion 14 is made of a high-hardness material so that it does not wear even if it is rubbed against the nut 18, or a wear-preventing coating is applied to the contact surface with the nut 18.

  A nut 18 made of a metal such as iron is inserted and placed in the insertion hole 16. A female screw 20 extending in the axial direction is formed at the center of the nut 18. The nut 18 has a flange portion 19 formed on the bottom portion and a main body portion 21 having a smaller diameter than the flange portion 19. The outer diameter of the flange portion 19 is smaller than the inner diameter of the insertion hole 16, and a gap is generated between them. Since the height of the nut 18 is larger than the depth of the insertion hole 16, the tip of the main body portion 21 protrudes outward from the cylindrical portion 14. The front end surface of the main body portion 21 serves as a seating surface with which the control board 34 contacts.

  An annular elastic body made of an elastic material, specifically, an O-ring 30 is inserted into the body portion 21 of the nut 18. The inner diameter of the O-ring 30 is smaller than that of the flange portion 19, and the outer shape is larger than that of the flange portion 19. Therefore, the O-ring 30 inserted through the main body portion 21 stays on the flange portion 19 and is packed between the outer peripheral surface of the nut 18 (the outer peripheral surface of the flange portion 19) and the inner peripheral surface of the insertion hole 16. It plays the role of maintaining the gap between the two.

  A mounting plate 32 is press-fitted into the upper end opening of the insertion hole 16. The mounting plate 32 is an annular flat plate having an outer shape larger than the inner diameter of the insertion hole 16 and an inner diameter larger than the outer diameter of the main body 21 of the nut 18. The mounting plate 32 is press-fitted into the upper end opening of the insertion hole 16 and pressed to a position where it hits the O-ring 30. Therefore, the mounting plate 32 functions as a caulking lid that presses the nut 18 against the bottom surface of the cylindrical portion 14.

  A mounting hole 40 is formed at a position corresponding to the fastening portion of the control board 34 to be fastened. As shown in FIG. 3, a plurality of the mounting holes 40 are formed in a distributed manner on the entire substrate. The inner diameter of each mounting hole 40 is sufficiently larger than the main body 28 of the bolt 22 described later, and smaller than the outer diameter of the head 25 of the bolt 22. A GND line is formed on the back surface of the control board 34 so that it can come into contact with a nut 18 described later. Note that, as will be described in detail later, in the present embodiment, a fastening structure is employed in which each fastening point can slide with respect to the PCU case 12. However, this slidable fastening structure is not used at all fastening locations, but is rigidly fixed so that the fastening location does not move relative to the PCU case 12 at only one location (for example, the mounting hole 40a in FIG. 3). The fastening structure is used.

  The bolt 22 for screwing and fastening the control board 34 to the nut 18 has a head portion 25 and a main body portion 28 to be screwed to the female screw 20 of the nut 18. When fastening the control board 34, the main body 28 is passed through the mounting hole 40, the male screw of the main body 28 is screwed into the female screw 20 of the nut 18, and the seat surface of the nut 18 and the bolt 22 are connected. The control board 34 is sandwiched by the head 25.

  Next, the reason why the fastening structure as described above is employed will be described. As described above, in this embodiment, the PCU 10 is directly mounted on the T / A case 102. In this case, since the PCU 10 that controls the power of the motor generators MG1 and MG2 can be installed in the vicinity of the motor generators MG1 and MG2, the wiring can be shortened and the space can be effectively used. On the other hand, T / A 100 is likely to generate vibrations including high-frequency vibrations as motor generators MG1, MG2 and transmission TM are driven. When the PCU 10 is directly mounted on the T / A 100, both the level and frequency of vibration input to the PCU 10 increase. Therefore, in order to reduce the influence of such vibration on the control board 34, it is conceivable to employ the high-rigidity PCU case 12, and to fasten the control board 34 to the high-rigidity PCU case 12 at multiple points. .

  Here, the conventional PCU case 12 is often made of resin, and in order to increase the case rigidity, it is often necessary to increase the thickness or add ribs. For this reason, attempts to increase rigidity with a resin case often resulted in an increase in the size of the entire case. In recent years, since the heat generation density tends to increase due to the improvement in the mounting density of the board, an efficient heat dissipation mechanism is essential. However, in order to release the heat from the control board 34 to the outside, A separate part made of a highly conductive material was required. In addition, since the resin case is non-conductive, it is necessary to provide another part made of a conductive material such as a bus bar in order to connect the control board 34 to the GND. That is, when a resin case is used, separate parts are required for heat dissipation and GND connection, which may increase the cost and further increase the size.

  Therefore, in the present embodiment, a metal case made of a metal such as aluminum is employed as the PCU case 12. By adopting a metal as the material of the PCU case 12, high rigidity can be secured without increasing the size of the entire case. Further, the metal has superior conductivity and heat conductivity as compared with the resin. Therefore, the metal case itself can be used for GND connection and heat dissipation of the control board 34. In other words, by adopting a metal case, GND connection and heat dissipation can be performed without adding other components, thereby preventing an increase in cost and further increase in size.

  However, when the control board 34 is fastened to the inner side surface of the metal PCU case 12, stress in the surface direction acts on the control board 34 due to a difference in linear expansion between the PCU case 12 and the control board 34. Sometimes. This will be described with reference to FIG. FIG. 4B is an image diagram showing a case where the control board 34 is rigidly fixed to the inner surface of the metal PCU case 12, that is, fixed and fastened so that the fastening portion of the control board 34 does not move with respect to the PCU case 12. It is.

  In the example of FIG. 4B, a boss seat 50 formed with a female screw is provided on the inner surface of the PCU case 12, and the control board 34 is sandwiched between the head of the bolt 22 and the boss seat 50 that are screwed into the female screw. Yes. In the case of such a fastening structure, the position of the control board 34 is fixed with respect to the PCU case 12.

  Here, the control board 34 is usually configured by mounting various circuit elements on a printed board on which a circuit pattern is formed of copper foil by soldering. The printed circuit board is made of an insulating resin such as an epoxy resin containing glass fiber, and has a smaller linear expansion coefficient than the metal constituting the PCU case 12. Therefore, when the control board 34 is rigidly fixed to the PCU case 12, there arises a problem that it cannot follow the expansion / contraction of the PCU case 12 having a large linear expansion coefficient.

  That is, the temperature of the interior of the vehicle varies greatly between day and night, summer and winter, and when traveling and when stopped. With this temperature change, the metal PCU case 12 having a large linear expansion coefficient expands and contracts, and the distance between the boss seats expands and contracts. On the other hand, the printed circuit board constituting the control board 34 is made of a resin having a smaller linear expansion coefficient than that of metal. Get smaller.

  For example, when the inside of the vehicle becomes cold, such as in winter, the control board 34 contracts, but the PCU case 12 contracts more than the contraction amount of the control board 34. As the PCU case 12 contracts, the distance between the bolts screwed into the PCU case 12 becomes smaller than the distance between the mounting holes formed in the control board 34, and the bolt 22 moves the control board 34 in the surface direction. Will be pressed. By this pressing, a compressive stress acts on the control board 34, and the control board 34 bends as shown by a two-dot chain line in FIG. 4B.

  Conversely, when the interior of the vehicle becomes hot, such as in summer, the control board 34 expands, but the PCU case 12 expands more than the expansion amount of the control board 34. With the expansion of the PCU case 12, the bolt 22 whose distance between the bolts has increased presses the control board 34 in the surface direction, so that a tensile stress acts on the control board 34.

  That is, by repeating the temperature fluctuation, compressive stress and tensile stress are repeatedly applied to the control board 34, causing fatigue of the control board 34 and the circuit pattern, cracking of the solder attached to the circuit element, and the like.

  In this embodiment, the fastening structure using the nut 18 attached to the PCU case 12 via the O-ring 30 is employed in order to avoid such a problem. This will be described with reference to FIG. FIG. 4A is a schematic view of the fastening structure of the present embodiment.

  As described above, in this embodiment, the control board 34 is sandwiched between the seating surface of the nut 18 and the head 25 of the bolt 22, and these three members are firmly fastened. On the other hand, the nut 18 is pressed against the PCU case 12 by the pressing force of the mounting plate 32, and an O-ring 30 is interposed between the mounting plate 32 and the flange portion 19 of the nut 18. The vertical vibration can be effectively absorbed by the elastic force of the O-ring 30. In particular, when the PCU 10 is directly mounted on the T / A case 102, high-frequency vibration is generated as the motor generator is driven. In this embodiment, since the O-ring 30 is interposed, high-frequency vibration is also generated. Can be absorbed stably.

  Further, according to the present embodiment, an excessive portion of the pressing force of the mounting plate 32 is absorbed by the O-ring 30, so that the connecting force between the nut 18 and the PCU case 12 is relatively small. A certain amount of gap is provided between the maximum outer periphery of the nut 18 and the inner peripheral surface of the insertion hole 16. Therefore, the nut 18, the bolt 22 and the control board 34 that are firmly connected to the nut 18 can be relatively moved in the surface direction with respect to the PCU case 12 even with a relatively small force. As a result, the deviation caused by the difference in linear expansion coefficient between the PCU case 12 and the control board 34 can be absorbed.

  For example, consider a case where the interior of the vehicle is cold and the PCU case 12 contracts. In this case, the cylindrical part 14 provided in the PCU case 12 slides in a direction in which the distance between the cylindrical parts becomes smaller as shown in FIG. On the other hand, the nut 18 has a small fastening force with the PCU case 12 and a gap between the nut 18 and the inner peripheral surface of the insertion hole 16, so that the nut 18 and the bolt 22 fastened to the nut 18 are The control board 34 stays in place without following the PCU case 12 (cylindrical portion 14). The deviation due to the difference in linear expansion coefficient between the PCU case 12 and the control board 34 is absorbed by the O-ring 30, and no stress in the surface direction acts on the control board 34. As a result, deterioration of the circuit pattern formed on the control board 34, solder cracks, and the like can be effectively prevented, and the reliability of the control board 34 can be improved. Further, even when the cylindrical portion 14 is slid, the O-ring 30 continues to press the nut 18 with an appropriate force while being subjected to shear deformation. Even in this case, the vertical vibration can be effectively absorbed. .

  In the present embodiment, the control board 34 is directly placed on the seat surface of the iron nut 18. Therefore, the heat generated in the control board 34 is efficiently transmitted to the PCU case 12 through the iron nut 18 having a high heat transfer rate. As a result, it is possible to efficiently dissipate the heat generated by the control board 34 without using a separate component such as a sircon sheet. As a result, the PCU 10 can be reduced in size and cost. In addition, since heat can be efficiently dissipated, the control board 34 can be further densified and further downsized.

  Further, the GND line disposed on the back surface of the control board 34 is brought into contact with the seating surface of the iron nut 18 so that the GND line and the PCU case 12 can be electrically connected without using a separate part such as a bus bar. can do. As a result, noise can be reduced while enabling the PCU 10 to be reduced in size and cost.

  As described above, according to the present embodiment, the reliability of the PCU 10 can be improved while reducing the influence of vibration, and further, the PCU 10 can be reduced in size and cost.

  The configuration described above is an example, and the configuration may be changed as appropriate. For example, as shown in FIG. 5, a plurality of grooves 18 a extending in the radial direction may be provided on the seating surface of the nut 18. By providing the groove 18a, the rotation of the nut 18 with respect to the control board 34 is effectively prevented, and the screwing is effectively prevented from being loosened. The shape of the groove 18a is not particularly limited as long as it can be a resistance when the nut 18 rotates with respect to the control board 34, and may be a mesh pattern, for example.

  Further, when the groove 18a is provided on the seat surface of the nut 18, as shown in FIG. 6, a groove (FIG. 6) that engages with the groove 18a on the back surface of the control board 34 (the surface facing the nut 18). It is also possible to fix the washer 38 formed (not shown). In this case, it is desirable that the washer 38 is firmly fixed to the control board 34 by an adhesive or soldering. By providing the washer 38, the rotation of the nut 18 relative to the control board 34 is more reliably prevented.

  As another form, the nut 18 may be non-circular in top view (for example, a substantially rectangular shape in which arcs are formed at corners) as shown in FIG. In this case, the insertion hole 16 into which the nut 18 is inserted is also non-circular in top view (similar to the outer shape of the nut 18). By adopting such a configuration, the nut 18 is reliably prevented from rotating inside the insertion hole 16, and the loosening of the screwing is more reliably prevented. As shown in FIG. 7, when the nut 18 and the insertion hole 16 are elongated in one direction in a top view, the elongated direction is a fastening portion (mounting hole 40a) where the rigid fixing is performed. It is desirable to have an arrangement toward That is, as described above, in the present embodiment, only one of the plurality of fastening points is rigidly fixed so that the nut 18 and the insertion hole 16 (PCU case 12) do not move relative to each other. When the PCU case 12 expands and contracts with a change in temperature, the PCU case 12 slides relative to the nut 18 with reference to this rigid fixing location, for example, the fastening location corresponding to the mounting hole 40a in FIG. In other words, when a temperature change occurs, the sliding direction of each insertion hole 16 with respect to the nut 18 is a linear direction connecting the rigid fixing position (position corresponding to the mounting hole 40a) and the insertion hole 16. For example, in FIG. 3, the insertion hole 16 corresponding to the mounting hole 40b is in the direction of arrow B connecting the mounting hole 40a and the mounting hole 40b, and the insertion hole 16 corresponding to the mounting hole 40c is the mounting hole 40a and the mounting hole. Each slides in the direction of arrow C connecting 40c. When the nut 18 has a shape elongated in one direction when viewed from the top, the long direction and the sliding direction of the insertion hole 16 are made to coincide, that is, the nut 18 is long in a direction toward the rigid fixing portion. It is desirable to use a long shape.

  In the description so far, the mounting plate 32 that is separate from the cylindrical portion 14 is caulked and the nut 18 and the O-ring 30 are attached to the PCU case 12. However, as shown in FIG. The distal end of the portion 14 may be bent inward, and the flange portion 19 may be pressed and fixed to the bottom surface (PCU case 12) of the insertion hole 16 via the O-ring 30 at the distal end. In this case, the bent portion functions as a caulking lid that presses the nut 18 against the bottom surface of the cylindrical portion 14. And when it is set as this structure, since the attachment plate 32 becomes unnecessary, the number of parts as a whole can be reduced and cost can be reduced more.

  Moreover, although the case where the nut 18 was attached to the PCU case 12 was illustrated in the above description, the bolt 22 may be attached to the PCU case 12 as shown in FIG. In this case, it is desirable that the bolt 22 has a stepped shape having a flange portion 22a, an intermediate portion 22b having a smaller diameter than the flange portion 22a, and a male screw portion 22c having a smaller diameter than the intermediate portion 22b. And after installing the said volt | bolt 22 in the inside of the cylindrical part 14 formed in PCU case 12 so that the flange part 22a may turn down, it is flanged via the O-ring 30 arrange | positioned at the flange part 22a. The part 22a is pressed against the PCU case 12, and the bolt 22 is fixed. When mounting the control board 34, the control board 34 is set so that the mounting hole 40 of the control board 34 passes through the male screw portion 22c. Then, the nut 18 is screwed into the male screw portion 22 c, and the control board 34 is sandwiched between the nut 18 and the intermediate portion 22 b of the bolt 22. With this configuration, the back surface of the control board 34 is in contact with the stepped surface between the intermediate portion 22b and the male screw portion 22c. This contact enables GND connection via the bolt 22 and heat dissipation. Further, since the bolt 22 is pressed against the PCU case 12 with a relatively small force through the O-ring 30, even if the PCU case 12 expands and contracts due to a temperature change, it does not follow the PCU case 12. Stay on the spot. As a result, no stress in the surface direction acts on the control board 34. Since fatigue deterioration of the control board 34 hardly occurs, the life and reliability of the control board 34 can be improved.

  12 PCU case, 14 cylindrical part, 16 insertion hole, 18 nut, 19 flange part, 22 bolt, 30 O-ring, 32 mounting plate, 34 control board, 38 washer, 40 mounting hole, 50 boss seat, 100 T / A , 102 T / A case.

Claims (4)

A fastening structure for fastening a control board in a metal case of a power control unit mounted directly on an in-vehicle transaxle,
A cylindrical portion provided on the inner surface of the metal case;
A nut having a flange portion at a proximal end, and the nut accommodated in the tubular portion so that the flange portion contacts the bottom surface of the tubular portion;
An elastic ring made of an elastic material, disposed on the flange portion, and packed between an outer peripheral surface of the nut and an inner peripheral surface of the tubular portion;
A crimping lid formed by bending the tip of the cylindrical part inward or caulking a plate material at an upper end opening of the cylindrical part, wherein the flange part is connected to the bottom surface of the cylindrical part via the elastic ring. A caulking lid to be pressed against,
A bolt that passes through a mounting hole formed in the control board and is screwed into the nut;
A fastening structure comprising: The fastening structure according to claim 1,
The said control board is mounted in the seat surface which is the front end surface of the said nut, The fastening structure characterized by the above-mentioned. The fastening structure according to claim 1 or 2,
A fastening structure in which a groove serving as a rotational resistance of the nut with respect to the control board is formed in a seating surface which is a front end surface of the nut. A fastening structure for fastening a control board in a metal case of a power control unit mounted directly on an in-vehicle transaxle,
A cylindrical portion provided on the inner surface of the metal case;
A bolt having a flange portion at its proximal end, the bolt being housed in the tubular portion so that the flange portion contacts the bottom surface of the tubular portion;
An elastic ring made of an elastic material, disposed on the flange portion, and packed between the outer peripheral surface of the bolt and the inner peripheral surface of the tubular portion;
A crimping lid formed by bending the tip of the cylindrical part inward or caulking a plate material at an upper end opening of the cylindrical part, wherein the flange part is connected to the bottom surface of the cylindrical part via the elastic ring. A caulking lid to be pressed against,
A nut screwed with a male screw of the bolt penetrating through a mounting hole formed in the control board;
A fastening structure comprising:

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