JP2012023331A - Manufacturing method for case mold type capacitor and bus bar used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a case mold type capacitor used for such things as a hybrid automobile which can achieve cost reduction even though it is small, light, and of low ESL.SOLUTION: A N pole bus bar is configured integrally by jointing multiple N pole division bus bars 6 to 8 with junctions 6a, 6b, 7a, and 8a on their ends by matching the junctions 6a and 6b and the junctions 7a and 8a while the junctions 6a, 6b, 7a, and 8a are cut diagonally in relation to the width direction of a substrate to configure the N pole division bus bars 6 to 8 so that the cross-sectional area of the juncture is bigger than the cross-sectional area in th case where the juncture is along the width direction of the substrate. Also, reinforcement parts 6c, 6d, 7b, 8b, and 8c which are formed by extending the substrate partially to both ends of each of the junctures are provided so that cost reduction can be achieved by material yield improvement and the size of the bus bar and the generation of unwanted resistance can be prevented.

Description

  INDUSTRIAL APPLICABILITY The present invention is used in various electronic equipment, electrical equipment, industrial equipment, automobiles, etc., and in particular, a metallized film capacitor that is optimal for smoothing, filtering, and snubbing of a motor drive inverter circuit of a hybrid car is accommodated in a case. The present invention relates to a resin mold-molded case mold type capacitor and a method of manufacturing a bus bar used therefor.

  In recent years, from the viewpoint of environmental protection, all electric devices are controlled by inverter circuits, and energy saving and high efficiency are being promoted. In particular, in the automobile industry, hybrid vehicles (hereinafter referred to as HEVs) that run on electric motors and engines have been introduced into the market, and the development of technologies relating to energy saving and high efficiency has been activated, which is friendly to the global environment.

  Since such a HEV electric motor has a high operating voltage range of several hundred volts, a metallized film capacitor having high withstand voltage and low loss electric characteristics as a capacitor used in connection with such an electric motor. In addition, the trend of adopting metalized film capacitors with a very long life is conspicuous due to the demand for maintenance-free in the market.

  Such metallized film capacitors are roughly classified into those generally using a metal foil as an electrode and those using a deposited metal provided on a dielectric film as an electrode. Among these, metallized film capacitors that use vapor-deposited metal as an electrode (hereinafter referred to as metal vapor-deposited electrode) have a smaller volume occupied by the electrode compared to that of metal foil and can be reduced in size and weight. High reliability in dielectric breakdown due to recovery function (capacity of metal evaporated electrode around the defective part evaporates and scatters and insulates when the short-circuit occurs in the defective part) Therefore, it has been widely used conventionally.

  In addition, when the metallized film capacitor configured as described above is used for HEV, it is strongly required to increase the withstand voltage, increase the current, increase the capacity, etc. of the operating voltage. A case mold type capacitor in which a metallized film capacitor is housed in a case and a mold resin is cast in the case has been developed and put into practical use.

  7A and 7B are a plan sectional view and a front sectional view showing the structure of this type of conventional case mold type capacitor. In FIG. 7, 21 is a resin capacitor case, and 22 is a capacitor element. Indicates. Reference numerals 23a and 23b are integrally connected fittings, 23a being a part built in the capacitor case 21, and 23b being a part protruding from the capacitor case 21 to the outside. Reference numeral 24 denotes a filling resin such as an epoxy resin for fixing the capacitor element 22; 25, an electrode portion; 26, a mounting leg for attaching a case mold type capacitor to the outside; and 27, a casting surface for casting the filling resin 24 It is.

  Then, the connection fitting 23a is connected to the electrode portion 25 of the capacitor element 22, and the connection fitting 23b (connected integrally with the connection fitting 23a) is connected to an external device or the like, thereby connecting the electrode portion 25 and the external device or the like. Electrically connected. The capacitor case 21 includes the entire capacitor element 22 and a connection fitting 23a, and is fixed by filling a filling resin 24 therein. In FIG. 7, the bottom portion (casting surface 27) of the capacitor case 21 is an opening surface before resin filling, and this opening surface is a surface for casting the filling resin 24. Further, the connection fitting 23 b is exposed from the casting surface 27 and led out from the capacitor case 21.

  The conventional case mold type capacitor configured as described above can suppress the inductance without increasing the overall height of the case mold type capacitor.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2003-338425 A

  However, when the conventional case mold type capacitor is used for HEV, a plurality of capacitor elements for smoothing an inverter circuit for driving a motor of a hybrid vehicle are accommodated in one case, and further, a filter Since a plurality of capacitor elements for use as a snubber or a snubber are housed in one case together with a plurality of smoothing capacitor elements and are resin-molded, a plurality of capacitor elements are used in this way. Must be connected in parallel by a pair of bus bars, the shape of the bus bar becomes complicated and the material yield becomes extremely bad, and a lot of space is required for the transportation and storage of the bus bar, and the efficiency is poor. And workability will be worse, and all these problems will lead to higher costs. There was.

  Therefore, as one of possible means for solving such problems, it is possible to divide the bus bar into a plurality of parts, and combine the divided parts into one to produce one bus bar. Such a method has been studied and proposed in Japanese Patent No. 3562431.

  In other words, it proposes a method that makes it possible to produce a large bus bar with a size exceeding the size of the bus bar punching die. Specifically, the maximum size of the bus bar that can be punched with the punching die If the size of the bus bar placed on the same plane exceeds the size, the bus bar constituting the same layer is divided into a plurality of parts, and the conductive metal plate is punched in multiple times with a punching die. The plurality of bus bars separately punched and formed are disposed opposite to each other on the same plane and provided with connection ends on the same plane, and the connection ends are extended without being refracted. Conduction by press-connecting both ends of the wire or a plate made of a conductive material, or by connecting the connection end to a female terminal connected to the end of the wire, or by overlapping the connection ends vertically Welded , Is that "to form a bus bar circuit.

  However, although it is possible to produce a large bus bar by producing a bus bar using such a technique and to improve the material yield by devising a dividing method, a plurality of bus bars can be used as electric wires or plate materials. In connection methods such as connecting via a cable or welding multiple bus bars stacked one on top of the other, the bus bar becomes unnecessarily large and increases in weight, and unnecessary resistance is generated. There is a problem, and bus bars used for HEVs such as the present invention are not only reduced in cost by improving the material yield, but also require small size, light weight and low ESL. There was a problem that it was not possible.

The present invention solves such a conventional problem, and provides a case mold type capacitor capable of realizing cost reduction without sacrificing small size and light weight and low ESL, and a method of manufacturing a bus bar used therefor. It is intended to provide.

  In order to solve the above problems, the present invention provides a case mold type capacitor in which a plurality of capacitor elements are connected to each other by a bus bar provided with a terminal portion for external connection at one end and accommodated in a case, and these are resin molded. A bus bar is formed by integrating a plurality of divided bus bars each provided with a joint at one end by abutting and joining each of the joints, and the width of the base material in which each of the joints constitutes the divided bus bar In addition to being cut in an oblique direction with respect to the direction, a reinforcing portion in which a base material is partially extended is provided at both ends of each joint portion.

  As described above, the case mold capacitor according to the present invention and the method of manufacturing the bus bar used therefor are provided with a joint cut at an angle with respect to the width direction of the base material at one end, and based on both ends of the joint. By combining the joints of multiple divided busbars that are provided with reinforcing parts that are partly extended from each other and joining them together, the material yield is improved by dividing the busbars and the cost is reduced. In addition to being able to achieve this, it is possible to obtain an effect that the bus bar is not enlarged and unnecessary resistance is not generated by the butt joining.

  Further, for example, when the joint portions of the divided bus bars are joined by laser welding, the joint portion is cut in an oblique direction with respect to the width direction of the base material, so that the cross-sectional area of the weld portion is the width of the bus bar. Since it is larger than the cross-sectional area when cut along the direction, it is possible to stabilize the welding strength, and at the start side or the end side during laser welding, the reinforcing parts provided at both ends of the joint part Even if partial cracking due to melting occurs, the bonding strength can be sufficiently ensured.

The top view before the resin mold which showed the composition of the case mold type capacitor by one example of the present invention The perspective view which showed the structure of the N pole bus bar used for the case mold type capacitor (A)-(c) The top view which showed the N pole division | segmentation bus bar which comprises the N pole bus bar shown in FIG. The perspective view for demonstrating the manufacturing method of the bus-bar used for the same case mold type capacitor The perspective view for demonstrating the manufacturing method of the bus-bar used for the same case mold type capacitor Cross-sectional conceptual diagram showing the joint of the bus bar used in the case mold type capacitor (A) Plan sectional drawing which showed composition of conventional case mold type capacitor, (b) Front sectional view

  Hereinafter, the present invention, particularly the inventions described in all claims, will be described using examples.

FIG. 1 is a plan view showing a configuration of a case mold type capacitor according to an embodiment of the present invention before resin molding. In FIG. 1, 1 and 2 are metallized film capacitors (hereinafter referred to as capacitor elements 1 and 2). The capacitor elements 1 and 2 are a pair of metallized films having a metal vapor-deposited electrode formed on one or both sides of a dielectric film made of polypropylene, and the metal vapor-deposited electrodes face each other with the dielectric film interposed therebetween. A pair of extraction electrodes of a P electrode (not shown) and an N electrode (not shown) are formed by forming a metallicon electrode which is flattened by press working after being wound in a state and sprayed with zinc on both end faces. Are provided respectively.

  In the present embodiment, an example of a configuration with a total of four capacitor elements 1 and 2 in which two capacitor elements 1 are used for smoothing and two capacitor elements 2 are used for filtering. However, the present invention is not limited to this.

  Reference numeral 3 denotes a P pole bus bar, and 4 denotes an N pole bus bar. The P pole bus bar 3 and the N pole bus bar 4 connect the four capacitor elements 1 and 2 in parallel. The details of the N pole bus bar 4 will be described later. In FIG. 1, the P-pole bus bar 3 and the N-pole bus bar 4 are shown with a part omitted that is not directly related to the present invention to make the overall configuration easy to understand.

  5 is a box-shaped case made of a resin whose upper surface is opened (in this embodiment, PPS (polyphenylene sulfide) is used, but the present invention is not limited thereto), and 5a is attached to this case 5. It is a mounting leg for mounting on a device or the like, and a total of four capacitor elements 1 and 2 connected in parallel by the P-pole bus bar 3 and the N-pole bus bar 4 are accommodated in the case 5.

  In addition, the case 5 is filled with a mold resin (not shown) (in this embodiment, an epoxy resin is used, but the present invention is not limited to this). The most part of the four capacitor elements 1 and 2 except a part of the P pole bus bar 3 and the N pole bus bar 4 in which the total of four capacitor elements 1 and 2 are connected in parallel are fixed in the case 5. It is what you are doing.

  FIG. 2 is a perspective view showing the configuration of the N-pole bus bar 4, and FIGS. 3A to 3C are divided into three parts in order to explain the configuration of the N-pole bus bar 4 shown in FIG. FIG. 4 is a plan view showing a punched N pole divisional bus bar before bending, and in FIG. 2 and FIG. 3, this N pole bus bar 4 will be described as an example, but the P pole bus bar 3 is also an N pole bus bar. 4 is configured in a divided structure, and detailed description thereof is omitted here.

  In FIG. 2, 4 is an N pole bus bar, 4a, 4b, 4c are terminal portions provided by bending a part of the N pole bus bar 4, and the terminal portions 4a, 4b, 4c are the case 5 described above. Each of them is exposed from a mold resin (not shown) filled therein.

  Further, the N pole bus bar 4 is manufactured by joining the punched parts into the three-part structure divided along the line AA in the figure, and by bending a predetermined part. The N pole bus bar 4 (hereinafter referred to as the N pole split bus bar 6, the N pole split bus bar 7, and the N pole split bus bar 8) punched into the above three split structure is shown in FIG. 3 (a) to 3 (c) will be described in detail.

  In FIG. 3, 6a and 6b at one end of the N-pole divided bus bar 6, 7a at one end of the N-pole divided bus bar 7, and 8a at one end of the N-pole divided bus bar 8 respectively represent the N-pole bus bar 4 shown in FIG. It is a junction formed when divided by the A line, and this junction 6a, 6b, 7a, 8a was cut in an oblique direction with respect to the width direction of the N pole bus bar 4 (W direction shown in FIG. 2). In this way, by cutting in an oblique direction, the cross-sectional area of the joints 6a, 6b, 7a, 8a is compared with the cross-sectional area in the case of cutting along the width direction (W direction shown in FIG. 2). It is intended to be larger.

  6c, 6d, 7b, 8b, 8c are reinforcing portions provided so as to partially extend the base material at the start and end in the cutting direction of the joint portions 6a, 6b, 7a, 8a, and 6e, 7c are the capacitor elements. Connection portions 6f, 7d, and 8d that are soldered and connected to the N-pole electrodes formed in 1 and 2 are through-holes, and some of the through-holes 6f, 7d, and 8d are N-pole divided bus bars 6 to 6 described later. When the 8 is joined together, it is inserted into a positioning pin (reference numeral 9a shown in FIG. 4) provided on the jig and used for positioning.

  Next, a method for manufacturing the N pole bus bar 4 configured as shown in FIGS. 2 and 3 will be described in detail. The P pole bus bar 3 is also configured in a divided structure in the same manner as the N pole bus bar 4. Since it is a thing, description here is abbreviate | omitted.

  FIG. 4 is a perspective view for explaining a method of manufacturing the N-pole bus bar 4. In FIG. 4, 6 to 8 denote N-pole divided bus bars divided into three, 9 denotes a jig for manufacturing the bus bar, The three N-pole divided bus bars 6 to 8 are placed at predetermined positions on the jig 9 to perform a joining operation.

  Specifically, as shown in FIG. 4, three N-pole divided bus bars 6 to 8 are arranged at predetermined positions. That is, it arrange | positions so that the junction part 6a of the N pole division | segmentation bus bar 6 and the junction part 7a of the N pole division | segmentation bus bar 7 may contact | abut in abutting state, and it joins the junction part 6b of the N pole division | segmentation bus bar 6 and the N pole division | segmentation bus bar 8 It arrange | positions so that the part 8a may contact | abut in a butt | matching state. At this time, the positioning pin 9a provided on the jig 9 is provided on the through hole 6f provided on the N pole division bus bar 6, the through hole 7d provided on the N pole division bus bar 7, and the N pole division bus bar 8. By fitting the through holes 8d, the three N-pole divided bus bars 6 to 8 are respectively positioned at predetermined positions.

  Subsequently, as shown in FIG. 5, the jigs 10 and 11 are placed on the upper surfaces of the N-pole divided bus bars 6 to 8 which are respectively arranged on the jig 9 and positioned at predetermined positions. The positioning of the jigs 10 and 11 with respect to the jig 9 is performed by fitting the through holes 10a provided in the jig 10 into the positioning pins 9b provided in the jig 9 and the holes provided in the jig 11. 11a is inserted into a positioning pin 9b provided on the jig 9.

  Subsequently, a laser beam (not shown) is irradiated to the portion where the three N pole division bus bars 6 to 8 positioned at predetermined positions through the jigs 9, 10, and 11 are in contact with each other. By performing laser welding, the three N pole division bus bars 6 to 8 are integrated to produce the N pole bus bar 4. Note that the present invention is not limited to such laser welding, and the three N pole division bus bars 6 to 8 are integrated in the same manner by any one of electron beam welding and solid phase bonding (friction stir welding). It is possible to produce the N pole bus bar 4.

  The case mold type capacitor according to the present embodiment configured as described above is an N pole bus bar in which the N pole bus bar 4 having a complicated shape is divided and three N pole divided bus bars 6 to 8 are joined and integrated. 4 has a special effect that the material yield can be greatly improved by the configuration and manufacturing method in which the N pole bus bar 4 is not divided in this embodiment. The material yield is about 20%, but the material yield is improved to about 50% by dividing.

Furthermore, the effect of splitting the bus bar is not only cost reduction by improving the material yield, but also lowering the ESL by dividing the bus bar so that the current path is the shortest, and depending on the flowing current and frequency Since it is easy to optimize the thickness of the bus bar by reducing the thickness of the bus bar, or by increasing the thickness of parts that require strength by fastening bolts, etc., it enables extremely efficient bus bar design and reduces weight. There is an extraordinary effect that it is possible to plan.

  Further, in performing the above-described joining operation, in the present invention, the joining portions 6a, 6b, 7a, and 8a of the three N-pole divided bus bars 6 to 8 are butted together and joined, Not only does the bus bar increase in size and unnecessary resistance is generated, but also the two junctions 6a, 6b, 7a, and 8a of the three N-pole divided bus bars 6 to 8 are joined together. Since the two connecting portions are arranged on the same line, the two connecting portions can be continuously joined, so that an efficient joining operation can be performed. This is a special effect.

  In addition, since the cross-sectional area of the joints 6a, 6b, 7a, 8a is larger than the cross-sectional area when cut along the width direction of the base material, the joint strength is increased by increasing the joint area. In addition, the structure provided with the reinforcing portions 6c, 6d, 7b, 8b, and 8c provided so as to partially extend the base material at the start and end in the cutting direction can be used. Even if a part of the substrate due to melting of the starting end side or the terminal end side is partly lost, the bonding strength can be sufficiently ensured.

  In addition, in order to further stabilize the above-mentioned bonding strength, the output of the bonding apparatus at the start and end during laser welding (the same applies to electron beam welding and solid phase bonding) should be lower than the same output at other parts. In addition, it is preferable to make the tact time of the joining work at the start and end times during the same work slower than the tact time at other parts.

  Further, as shown in detail in FIG. 6, the joint portions where the respective joint portions 6 a, 6 b, 7 a, and 8 a are brought into contact with each other and joined are joined as shown in FIG. 6. On the other hand, it is preferable to join so that the same bead width dimension B2 on the back surface side is 40% or more, and below this, there is a possibility that the molten state of the base material on the back surface side varies and the bonding strength decreases. For this reason, it is not preferable.

  Moreover, since the back surface side of the connection part 12 which joined each said joining part 6a, 6b, 7a, 8a each butted | joined may melt | dissolve and the base material which melted | cured may swell beyond the thickness of this base material, If the N pole bus bar 4 is disposed so that the back side faces the capacitor elements 1 and 2, the connecting portion 12 of the N pole bus bar 4 may be in contact with the capacitor elements 1 and 2, which is not preferable. It is preferable to dispose the surface on the processing start side so as to face the capacitor elements 1 and 2, and this also applies to the P-pole bus bar 3.

  In the present embodiment, as an example of the configuration for dividing the P-pole bus bar 3 and the N-pole bus bar 4, the description has been given using an example in which the substrate is cut linearly in an oblique direction with respect to the width direction of the base material. The present invention is not limited to this, and may be combined with a curved shape such as an S shape or a wave shape with respect to the width direction of the substrate, or an S shape in an oblique direction with respect to the width direction of the substrate. It is also effective to cut into a combined shape of a curve such as a wave shape, and the cross-sectional area of the joint can be increased by cutting into a combined shape of a curve such as an S-shape or a wave shape. As in the above embodiment, the bonding strength can be stabilized.

  Furthermore, when joining joints having such a combination of curves such as S-shape and wave shape by laser welding, a plurality of curves are continuous as the combination shape of curves such as S-shape and wave shape. Due to the configuration, the laser beam can be irradiated while continuously running at a constant speed, and as a result, there is an effect that a stable welding operation can be performed.

  The case mold type capacitor according to the present invention has an effect that it is possible to realize a cost reduction without sacrificing a reduction in size and weight and a reduction in ESL, particularly in the field of automobiles such as hybrid vehicles. It is useful as a capacitor.

DESCRIPTION OF SYMBOLS 1, 2 Capacitor element 3 P pole bus bar 4 N pole bus bar 4a, 4b, 4c Terminal part 5 Case 5a Mounting leg 6, 7, 8 N pole division | segmentation bus bar 6a, 6b, 7a, 8a Junction part 6c, 6d, 7b, 8b , 8c Reinforcement part 6e, 7c Connection part 6f, 7d, 8d, 10a Through hole 9, 10, 11 Jig 9a, 9b Positioning pin 11a Hole 12 Connecting part

Claims (8)

A plurality of capacitor elements each provided with a pair of electrodes on both end faces are connected by a pair of bus bars each having a terminal portion for external connection at one end, and these are accommodated in a case to remove at least the terminal portions of the bus bar. In the case mold type capacitor molded by resin, the pair of bus bars are configured by integrating a plurality of divided bus bars each provided with a joint at one end by abutting each joint to each other, and the above A case mold in which each joint portion is cut in an oblique direction with respect to the width direction of the base material constituting the divided bus bar, and a reinforcing portion in which the base material is partially extended is provided at both ends of each joint portion. Type capacitor. The pair of bus bars are integrated by joining at least three divided bus bars, and at least two of the connecting parts joining the joining parts are arranged on the same line. The case mold type capacitor according to claim 1. The case mold type capacitor according to claim 1, wherein each of the divided bus bars is provided with a through hole. The case mold type capacitor according to claim 1, wherein the joint processing start side surface of each connection portion where the joint portions of the divided bus bars divided into a plurality of portions are arranged to face the capacitor element. The bonding beat width dimension on the back surface side is 40% or more with respect to the bonding beat width dimension on the surface on the bonding work side of each connecting portion where the joint portions of the divided bus bars divided into a plurality are joined. The case mold type capacitor according to 1. A joint portion cut in an oblique direction with respect to the width direction of the base material is provided at one end, a reinforcing portion in which the base material is partially extended is provided at both ends of the joint portion, and a plurality of through holes are provided. A plurality of divided bus bars are prepared and arranged on the jig in a state in which the respective joint portions provided on the plurality of divided bus bars are in contact with each other, and a plurality of through holes provided in the divided bus bars are provided in the jig. Each segmented bus bar is positioned at a predetermined position by inserting it into the positioning pin, and in this state, the part where the joints of each segmented bus bar are in contact with each other is either laser welded, electron beam welded or solid phase joined. A method of manufacturing a bus bar in which a plurality of divided bus bars are joined together to produce a single bus bar by joining using such a method. The bus bar according to claim 6, wherein the output of the joining device at the start and end at the time of joining work using any one of laser welding, electron beam welding, and solid phase joining is lower than the same output at other portions. Manufacturing method. The bus bar according to claim 6, wherein the tact of the manufacturing operation at the start and end at the time of joining work using any one of laser welding, electron beam welding, and solid phase joining is made slower than that at the other part. Manufacturing method.

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