JP2020120520A - Manufacturing method of electrical machine - Google Patents

Abstract

To provide a technology capable of preventing deviation of the screw passage hole of a bus bar and the screw receiving hole of the enclosure.SOLUTION: An electrical machine manufactured by the manufacturing method includes an enclosure having a terminal projecting outward and a screw receiving hole, a weld zone welded to the terminal, and a bus bar having a screw passage hole. The terminal inclines in the direction approaching the screw receiving hole as projecting from the enclosure in the natural shape, and a projection end deforms elastically in the direction separating from the screw receiving hole, by applying a force in the direction for pushing the bus bar against the terminal from the screw receiving hole. The manufacturing method includes a step of matching the positions of the screw receiving hole and the screw receiving hole, by applying a force having a direction component for pushing the bus bar against the enclosure and a direction component for pushing the bus bar against the terminal from the screw receiving hole, a step of welding the terminal and the weld zone while applying a force to the bus bar, a step of releasing force, and a step of screwing the screw passage hole and the screw receiving hole while releasing the force.SELECTED DRAWING: Figure 3

Description

The technique disclosed in the present specification relates to a method for manufacturing an electric device. In particular, the present invention relates to a method of manufacturing an electric device including a housing having a terminal projecting to the outside and a screw receiving hole, and a bus bar having a welding portion to be welded to the terminal and a screw passage hole.

There is known a technique of housing electric components such as a reactor and a capacitor in a housing. There is also known a technique of connecting an electric component inside the casing and an electric component outside the casing by a bus bar extending outside the casing. In order to connect the bus bar outside the housing to the electrical parts inside the housing, a part of the conductor extending from the electrical parts inside the housing is projected outside the housing, and the protruding portion is used as a terminal, and the bus bar is welded to the terminal. Is also known.

A bus bar extending outside the housing may be screwed to the housing. According to this technique, the bus bar is fixed to the housing at two points, a welding point and a screwing point, and the fixing strength of the bus bar is reinforced. There is also known a technique in which another bus bar (which will be referred to as a second bus bar for convenience) is fastened together at the screwed portion. According to this, the positional relationship between the housing and the bus bar is stabilized, and at the same time, the second bus bar is connected to the bus bar.

In the method of manufacturing the electric device by fixing the bus bar to the housing, the following is performed.
(1) Position the bus bar and the housing so that the screw passage holes formed in the bus bar and the screw receiving holes formed in the housing are aligned with each other so that the relative positional relationship between them does not move. Fix it.
(2) Weld the terminal of the housing and the welded portion of the bus bar in the fixed state.
(3) Remove the fixing jig and tighten the screws in the screw passage holes of the bus bar and the screw receiving holes of the housing.

The technique disclosed in the present specification relates to a method for manufacturing an electric device including the above-described bus bar, and solves a problem caused by variations in the size of the bus bar. As a technique for absorbing the variation in the dimensions of the bus bar, for example, the technique disclosed in Patent Document 1 is known. In Patent Document 1, in order to absorb the dimensional variation of the bus bar, a cushioning material is provided at one end of the bus bar. In this technique, the cushioning material is deformed when the dimensions of the busbar vary, thereby reducing the amount of deformation of the busbar due to the force connecting the busbar and the terminal.

JP, 2005-064398, A

In the above manufacturing method, in the case of (1), it is necessary to prevent the terminals of the housing and the welded portions of the bus bar from interfering with each other. Since the parts to be used have shape tolerances, a gap is actually created between the terminals of the housing and the welded parts of the bus bar in the step (1). In that state, the terminal and the welded portion are brought into contact with each other to perform welding, so that welding is performed in a state where internal stress remains in the terminal. As a result, when the fixing jig is removed in (3) above, the terminal is deformed by the stress remaining in the terminal, and the bus bar is also displaced accordingly. As a result, the screw passing hole of the bus bar and the screw receiving hole of the housing may deviate from each other, and a phenomenon in which they cannot be screwed may occur. When the second bus bar is fastened together, the bus bar and the second bus bar may interfere with each other, and the two bus bars may not be placed in the positional relationship of fastening both together. Alternatively, for co-fastening, three holes, that is, the screw passing hole of the second bus bar, the screw passing hole of the bus bar, and the screw receiving hole of the housing must be aligned on the same axis. There is a phenomenon that they are not aligned and cannot be tightened together.

According to the technique of Patent Document 1, the phenomenon in which the screw passing hole of the bus bar and the screw receiving hole of the housing are misaligned, and further, the screw passing hole of the second bus bar, the screw passing hole of the bus bar, and the screw receiving hole of the housing are misaligned The phenomenon cannot be prevented. This specification discloses a technique for preventing the screw passing hole of the bus bar and the screw receiving hole of the housing from being displaced from each other due to the residual stress generated in the terminal during welding.

An electric device manufactured by the technology disclosed in the present specification includes a housing having a terminal protruding to the outside and a screw receiving hole, and a bus bar having a welding portion to be welded to the terminal and a screw passage hole. ing. In addition, in this electric device, the welding portion of the bus bar is welded to the terminal, and the screw is fastened to the screw passage hole of the bus bar and the screw receiving hole of the housing. In its natural shape, the terminal is inclined in the direction closer to the screw receiving hole as it protrudes from the housing, and the protruding end is separated from the screw receiving hole by applying a force in the direction of pressing the bus bar from the screw receiving hole to the terminal. It is elastically deformed in the direction to do.

The method for manufacturing an electric device disclosed in the present specification applies a force having a directional component that pushes the busbar to the housing and a directional component that pushes the busbar to the terminal from the side of the screw receiving hole to the busbar, and the screw passage hole and the screw The step of aligning the positions of the receiving holes is provided. It also has the steps of welding the terminal and the welded portion with force applied to the bus bar, releasing the force, and screwing the screw passing hole and the screw receiving hole with the force released. There is.

According to the manufacturing method described above, a force having a directional component that pushes the busbar against the housing and a directional component that pushes the busbar toward the terminal from the side of the screw receiving hole is applied to the busbar, and the positions of the screw passage hole and the screw receiving hole are aligned. Let At this time, the terminal of the housing is elastically deformed in the direction in which the protruding end is separated from the screw receiving hole. Weld the terminal and the welded part while the terminal is elastically deformed. That is, the terminal is welded to the bus bar while the internal stress in the direction returning to the natural shape remains. Then, in order to release the force, the terminal tries to return to its natural shape due to internal stress. The terminal that returns to its natural shape presses the bus bar against the housing. The bus bar is pressed against the terminal and does not move. The bus bar does not move from the position where the screw passing hole and the screw receiving hole where the bus bar is originally arranged match. As described above, according to the method for manufacturing an electric device disclosed in the present specification, in the state where the screw passage hole and the screw receiving hole are aligned with each other, residual stress is generated in the terminal in the direction of pressing the bus bar against the housing. By doing so, it is possible to prevent the screw passing hole of the bus bar and the screw receiving hole of the housing from being displaced.

Details of the technology disclosed in the present specification and further improvements will be described in the following “Description of Embodiments”.

It is sectional drawing which shows the components layout in the case of a power converter device. It is an expanded sectional view of the range A of FIG. 1 in a natural shape. It is an expanded sectional view of the range A of FIG. 1 in a positioning process. It is an expanded sectional view of the range A of FIG. 1 in a welding process. It is an expanded sectional view of the range A of FIG. 1 in an opening process. It is an expanded sectional view of the range A of FIG. 1 in a fastening process.

Prior to describing the manufacturing method of the embodiment, a power conversion device 2 that is an example of an electric device that is a target of the manufacturing method of the embodiment will be described with reference to FIG. 1. First, the layout of the electric components inside the case of the power conversion device 2 will be described. FIG. 1 is a cross-sectional view in which a side plate on the front side in the drawing of the case is cut. The power conversion device 2 is mounted on an electric vehicle such as an electric vehicle, a hybrid vehicle, or a fuel cell vehicle.

The case of the power conversion device 2 is vertically divided into an upper case 4 and a lower case 6. The lower case 6 is located below the upper case 4. The upper case 4 and the lower case 6 have substantially the same height, and divide the internal space of the case of the power conversion device 2 into two parts, up and down. The upper case 4 and the lower case 6 are fastened with bolts 8 at both ends in the Y-axis direction. The upper case 4 has an upper opening 38 at the center of the upper surface. The upper case 4 and the lower case 6 are both made of aluminum.

The power converter 2 includes a reactor 10, an electric current sensor 30, and electric components such as a laminated body. The upper case 4 is provided with a partition 42 that divides the interior into upper and lower parts, and the stack is fixed to the partition 42. The partition 42 has a central opening 40 at the center. The reactor 10 is fixed to the lower case 6, and the current sensor 30 is fixed to the upper case 4.

Further, a boss 36 is provided on the inner side surface of the upper case 4 on the Y axis negative side, and the current sensor 30 is fixed to the boss 36 by a bolt 32 via a sensor fixing portion 34. Further, a sensor bus bar 26 extending to the side opposite to the sensor fixing portion 34 is connected to the current sensor 30. The body of the current sensor 30 is made of resin, and the base of the sensor bus bar 26 is supported by the body of the current sensor 30 made of resin.

The reactor 10 includes a housing 14 made of resin and a terminal 12 that vertically projects from the surface of the housing 14 on the upper case 4 side to the outside of the housing 14. The terminal 12 is made of copper, for example. The magnetic core and the coil, which are the main body of the reactor 10, are housed in the housing 14. The terminal 12 corresponds to the lead wire of the coil. Legs 18 that extend to both sides in the Y-axis direction are provided on the bottom surface side of the housing 14 of the reactor 10. The leg portion 18 is fixed to a boss 16 provided on the bottom surface of the lower case 6 with a bolt 20.

The bus bar 24 is arranged so as to come into contact with the flat surface 22 provided on the upper surface of the housing 14. Although details will be described later, one end of a bus bar 24 is welded to the terminal 12 of the reactor 10. The other end of the bus bar 24 is fastened together with the sensor bus bar 26 by a bolt 28 on the housing 14. By this joint tightening, the bus bar 24 and the sensor bus bar 26 are connected to each other. When the bus bar 24 and the sensor bus bar 26 are electrically connected, the reactor 10 and the current sensor 30 are electrically connected. As will be described later in detail, in the power conversion device 2, the terminal 12 has the welded portion 24a (see FIG. 2) of the bus bar 24 welded thereto and the screw passage hole 24b (see FIG. 2) and the screw receiving hole 44b (see FIG. 2). ) Is an electric device in which the bolt 28 is fastened.

Hereinafter, the manufacturing process of the power conversion device 2 will be described with reference to FIGS. 2 to 6. 2 to 6 are enlarged cross-sectional views of the range shown in A of FIG. 2 to 6 are sectional views in which the reactor 10 and the bus bar 24 are cut along the YZ plane in the coordinate system of FIG. In the present embodiment, in the method of manufacturing the power conversion device 2, the step of connecting the bus bar 24 to the reactor 10 and the step of connecting the reactor 10 and the current sensor 30 via the bus bar 24 will be mainly described.

FIG. 2 shows a diagram in which the bus bar 24 before fastening is placed on the housing 14. The positional relationship between the naturally shaped terminal 12 and the bus bar 24 will be described with reference to FIG. As shown in FIG. 2, the housing 14 includes the terminal 12 protruding to the outside of the housing 14, a first recess 14b, and a second recess 14c adjacent to the Y-axis negative side of the first recess 14b. There is. A nut 44 is provided in the first recess 14b. The nut 44 includes a screw receiving hole 44b that is screwed with the bolt 28 (see FIG. 1). The bus bar 24 includes a welded portion 24a that faces the terminal 12, a screw passage hole 24b that faces the screw receiving hole 44b, and a flange 24c that extends toward the housing 14 at the Y-axis negative terminal. The flange 24c is loosely fitted in the second recess 14c. The surface of the flange 24c on the Y axis positive side and the surface of the second recess 14c on the Y axis negative side are in contact with each other. As shown in FIG. 2, the length of the terminal 12 in the Z-axis direction is represented by the symbol L. The plate thickness of the terminal 12 is represented by the symbol t. Further, the width of the terminal 12 in the X-axis direction is represented by the symbol w. The terminal 12 is a copper plate. A space a is provided between the terminal 12 and the bus bar 24.

As described above, the bus bar 24 is arranged so as to contact the flat surface 22 of the housing 14. In FIG. 2, the position of the screw receiving hole 44b and the position of the screw passing hole 24b of the bus bar 24 are the same. That is, the bus bar 24 is arranged at the correct position with respect to the housing 14. A distance a is provided between the welded portion 24 a of the bus bar 24 and the terminal 12 in a state where the bus bar 24 is arranged at the correct position with respect to the housing 14. The space a is a space that absorbs the shape tolerance of the housing 14, the terminal 12, and the bus bar 24. For example, when the outer shape of the bus bar 24 is manufactured smaller than the distance from the screw receiving hole 44b to the terminal 12, the distance a becomes large. Further, when the bus bar 24 is manufactured to have a large outer shape with respect to the distance from the screw receiving hole 44b to the terminal 12, the distance a becomes small. The interval a is provided so that the bus bar 24 can be arranged without interfering with the terminal 12 even if the bus bar 24 has the maximum outer shape within the allowable range of the shape tolerance.

In order to weld the terminal 12 and the welded portion 24a of the bus bar 24 sandwiching the space a, it is necessary to apply a load by a fixing jig and deform the tips so that the tips approach each other to bring the tips into contact with each other. When the terminal 12 and the tip of the welded portion 24a are welded in this manner, the terminal 12 is welded while internal stress remains. When the fixing jig is removed after welding and the load is released, the internal stress remaining in the terminal 12 deforms the terminal 12 in a direction away from the screw receiving hole 44b. Due to the deformation of the terminal 12, the bus bar 24 welded to the tip of the terminal 12 rotates in a direction in which the screw passage hole 24b is separated from the nut 44. As a result, the screw passage hole 24b of the bus bar 24 and the screw receiving hole 44b may be out of alignment with each other, and a phenomenon may occur in which they cannot be screwed together. Further, when the sensor bus bar 26 of the current sensor 30 (see FIG. 1) is fastened together, the rotated bus bar 24 and the sensor bus bar 26 may interfere with each other so that the two cannot be placed in the positional relationship of fastening both together. Alternatively, in order to tighten together, the three holes of the screw passage hole 26b (see FIG. 6) of the sensor bus bar 26, the screw passage hole 24b of the bus bar 24, and the screw receiving hole 44b must be aligned on the same axis. There is a phenomenon that some of the holes are not aligned and cannot be tightened together. Here, as shown in FIG. 2, the terminal 12 is closest to the bus bar 24 at the tip. In its natural shape, the terminal 12 is inclined with respect to the axial direction of the screw receiving hole 44b. More specifically, the terminal 12 in its natural shape is inclined in a direction closer to the screw receiving hole 44b as it protrudes from the housing 14. Hereinafter, a manufacturing method that can prevent the screw passing hole 24b of the bus bar 24 and the screw receiving hole 44b from being displaced by using the terminal 12 that is inclined as described above will be described.

The positioning step will be described with reference to FIG. In the positioning step, the position of the bus bar 24 is fixed so that the position of the screw passage hole 24b of the bus bar 24 does not shift with respect to the position of the screw receiving hole 44b. As described above, the surface of the flange 24c on the Y axis positive side is in contact with the surface of the second recess 14c on the Y axis negative side. Therefore, the position of the bus bar 24 in the Y-axis direction with respect to the housing 14 is determined by the portion where the flange 24c and the second recess 14c are in contact with each other. As shown in FIG. 3, the flange 24c is provided near the screw passage hole 24b. By determining the position of the bus bar 24 with respect to the housing 14 at a portion near the screw passage hole 24b, it is possible to suppress variations in the screw passage hole 24b with respect to the screw receiving hole 44b. Further, the bus bar 24 is pressed against the housing 14 with a load F1 from above the portion contacting the flat surface 22 of the housing 14 by the first pressing jig 50. As a result, the position of the bus bar 24 is not displaced. In the positioning step, the screw passage hole 24b of the bus bar 24 and the screw receiving hole 44b can be aligned with each other.

Further, as shown in FIG. 3, in the positioning step, the second pressing jig 52 applies a load F2 in the direction in which the tip of the welded portion 24a of the bus bar 24 is pressed against the terminal 12 from the screw receiving hole 44b. As described above, the terminal 12 is a copper plate. The terminal 12, which is a copper plate, is deformed by the load F2 in a direction away from the screw receiving hole 44b.

Here, the load F2 is a load that elastically deforms the terminal 12. When the load F2 is too large and the terminal 12 is plastically deformed, no elastic force is generated in the terminal 12 and the terminal 12 does not return to its natural shape. Therefore, the moment M (see FIG. 5) due to the terminal 12 described later is not generated. Therefore, as described below, the receiving jig 52a is prepared so that the deformation of the terminal 12 is within the range of elastic deformation. As shown in FIG. 3, in the positioning step, a receiving jig 52a for suppressing the load F2 of the second pressure jig 52 is provided on the Y-axis positive side of the tip of the terminal 12. When the tip of the terminal 12 moves to the maximum displacement b shown in FIG. 3, the terminal 12 contacts the receiving jig 52a. The receiving jig 52a prevents the terminal 12 from being further deformed in a direction away from the screw receiving hole 44b. The receiving jig 52a suppresses the deformation amount of the terminal 12 so that the deformation of the terminal 12 remains within the elastic deformation range.

The maximum displacement b at which the terminal 12 elastically deforms is determined by the following (Equation 1) using the yield point strain of the terminal 12 as εy, the length L of the terminal 12 (see FIG. 2), and the plate thickness t of the terminal 12. be able to.
b=εyL ² /3t (Equation 1)
In the positioning step, by arranging the receiving jig 52a at a position away from the tip of the naturally shaped terminal 12 by the maximum displacement b calculated by the equation 1, the deformation of the terminal 12 can be kept within the elastic deformation range. ..

The welding process will be described with reference to FIG. As described above, the bus bar 24 is pressed against the housing 14 with the load F1 by the first pressure jig 50. Further, the tip of the welded portion 24 a is pressed against the terminal 12 by the second pressure jig 52. The terminal 12 is elastically deformed in a direction in which the terminal 12 is pushed by the welding portion 24a and separated from the screw receiving hole 44b. That is, there is no gap a (see FIG. 2) between the welded portion 24a and the terminal 12, and the tip of the welded portion 24a and the tip of the terminal 12 are in contact with each other. In the welding process, the contact portion between the welded portion 24a and the tip of the terminal 12 is welded with a welding torch. A bead 46 is formed at the contact portion between the welded portion 24a and the tip of the terminal 12 by welding. The bead 46 holds the connection between the welded portion 24 a and the tip of the terminal 12.

The opening step will be described with reference to FIG. In the releasing step, the load F1 applied by the first pressure jig 50 and the load F2 applied by the second pressure jig 52 are released. When the load F2 is released, a load F3 that tries to return to the natural shape is generated in the terminal 12 due to internal stress. The load F3 is transmitted to the tip of the welded portion 24a via the tip of the terminal 12 and produces a moment M that rotates the bus bar 24 counterclockwise. The moment M pushes the bus bar 24 against the housing 14. Since the moment M presses the bus bar 24 against the housing 14, the position of the bus bar 24 is not displaced even if the load F1 is released. As described above, in the positioning step, the bus bar 24 is arranged so that the position of the screw receiving hole 44b and the position of the screw passing hole 24b of the bus bar 24 match. After welding the welded portion 24a of the bus bar 24 and the terminal 12 in the welding process, the moment M presses the bus bar 24 against the housing 14 even if the loads F1 and F2 of the first and second pressing jigs are released. The position of does not change. That is, according to the manufacturing method disclosed in this specification, residual stress in the direction of pressing the bus bar 24 against the housing 14 is generated in the terminal 12 in a state where the screw passage hole 24b and the screw receiving hole 44b are aligned with each other. By doing so, it is possible to prevent the screw passage hole 24b of the bus bar 24 and the screw receiving hole 44b provided in the nut of the housing 14 from being displaced.

The fastening process will be described with reference to FIG. In the fastening step, the sensor bus bar 26 of the current sensor 30 (see FIG. 1) is arranged from above so as to face the screw passage hole 24b of the bus bar 24 with the loads F1 and F2 (see FIG. 4) opened. Then, the bolt 28 that has passed through the upper opening 38 (see FIG. 1) and the middle opening 40 (see FIG. 1) is fastened from above. As described above, the terminal 12 pushes the welded portion 24 a of the bus bar 24 to generate the moment M, and the bus bar 24 is pressed against the housing 14. Therefore, the portion of the bus bar 24 where the screw passage hole 24b is provided is not displaced in the direction away from the screw receiving hole 44b. Therefore, it is possible to prevent the bus bar 24 from interfering with the sensor bus bar 26. Further, as described above, it is not displaced from the position adjusted in the positioning process. Therefore, it is possible to prevent the screw receiving hole 44b, the screw passage hole 24b of the bus bar 24, and the screw passage hole 26b of the sensor bus bar 26 from being displaced.

Points to be noted regarding the technique described in the embodiment will be described. The method of aligning the positions of the bus bar 24 and the housing 14 is not limited to the engagement of the flange and the recess. The position may be adjusted by engaging with another shape, or the position may be adjusted by using a jig. Further, the screw receiving hole may be provided in the housing without using the nut 44.

Further, in the embodiment, the terminal 12 is elastically deformed by managing the displacement of the terminal 12 by the receiving jig 52a, but the technique disclosed in this specification is not limited to this. For example, the terminal 12 may be elastically deformed by using the load F obtained from the maximum displacement b. Here, when the Young's modulus of the copper forming the terminal 12 is E and the width of the terminal 12 is w,
F=bEwt ³ /4L ³ (Equation 2). The terminal 12 may be elastically deformed in a direction away from the screw receiving hole 44b by applying the load F thus obtained to the terminal 12 via the welded portion 24a without using the receiving jig 52a.

Although the present specification discloses a method for manufacturing an electric device, the electric device is not limited to the power conversion device 2. The housing 14 is also not limited to the housing of the reactor 10.

Specific examples of the present invention have been described above in detail, 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 the present specification or the drawings exert technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Further, the technique illustrated in the present specification or the drawings can simultaneously achieve a plurality of purposes, and achieving the one purpose among them has technical utility.

2: Power converter 4: Upper case 6: Lower case 8, 20, 28, 32: Bolt 10: Reactor 12: Terminal 14: Housing 14b: First recess 14c: Second recess 16, 36: Boss 18: Leg 22: Flat part 24: Bus bar 24a: Welded parts 24b, 26b: Screw passage hole 24c: Flange 26: Sensor bus bar 30: Current sensor 34: Sensor fixing part 38: Upper opening 40: Middle opening 42: Partition 44: Nut 44b: Screw receiving hole 46: Bead 50: First pressing jig 52: Second pressing jig 52a: Receiving jigs F1, F2, F3: Load M: Moment b: Maximum displacement

Claims (1)

A housing provided with a terminal projecting to the outside and a screw receiving hole, and a bus bar provided with a welding portion to be welded to the terminal and a screw passage hole,
In its natural shape, the terminal is inclined in a direction closer to the screw receiving hole as it protrudes from the housing, and the protrusion is obtained by applying a force in a direction of pressing the bus bar from the screw receiving hole to the terminal. The end is elastically deformed in a direction away from the screw receiving hole,
A method of manufacturing an electric device, wherein the welding portion is welded to the terminal and screws are tightened in the screw passage hole and the screw receiving hole,
A force having a directional component that pushes the busbar against the housing and a directional component that pushes the busbar from the screw receiving hole toward the terminal are applied to the bus bar to match the positions of the screw passage hole and the screw receiving hole. Process,
Welding the terminal and the welded portion while applying the force to the bus bar;
Releasing the force,
A method of manufacturing an electric device, comprising a step of screwing the screw passing hole and the screw receiving hole with the force released.

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