JP2013045781A - Cooler and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooler where a cover plate is joined to a case without continuously welding an entire periphery of an opening of the case and leaking a cooling medium.SOLUTION: In a cooler 10, a seal ring 7 is buried on a case opening peripheral upper surface 4a so as to surround a case opening, and a cover plate 2 is placed thereon to be spot-welded at multiple positions (indicated by marks Pc and Ps) of the case opening peripheral upper surface 4a. The welded positions are located at the outer side of the seal ring 7 when viewed in a plane view from a direction perpendicular to the cover plate 2. Grooves 5 guiding a cooling medium from an inner edge 4b of the case opening peripheral upper surface 4a to the seal ring 7 are formed at positions of a case 4 facing the welding points across the seal ring 7 when viewed in the plane view from the direction perpendicular to the cover plate 2.

Description

  The present invention relates to a cooler that allows a refrigerant to pass therethrough.

  In the cooler, when joining the cover plate to the case, it is necessary to join the cover plate without a slight gap so that the refrigerant does not leak. As one technique for joining the cover plates so that the refrigerant does not leak, Patent Document 1 proposes a technique for continuously joining the entire periphery of the case opening by friction stir welding.

JP 2010-140951 A

  If the entire circumference of the case opening is continuously welded, liquid leakage (gas leakage) will not occur. However, this increases costs. The present specification provides a cooler in which a cover plate is joined to a case without continuously welding the entire circumference of the opening of the case, but preventing the refrigerant from leaking.

  In the technology disclosed in this specification, a seal ring is embedded in the upper surface around the case opening so as to go around the opening of the case formed in a container shape. A cover plate is placed thereon, and a plurality of locations on the upper surface around the opening are welded in a dotted manner from the top of the cover plate. Friction stir welding is suitable for welding. That is, the seal ring secures the seal between the case and the cover plate. However, the seal ring is vulnerable to heat. On the other hand, friction stir welding involves heat generation. In friction stir welding, the members are softened and plastically flowed by frictional heat, and the two members are locally mixed and joined. Therefore, the temperature may reach several hundred degrees locally. Therefore, if the vicinity of the seal ring is to be welded, the seal ring may be damaged by the heat of welding. If the wall thickness around the case opening is increased and a distance is secured between the welded portion and the seal ring, the thermal problem can be solved, but this increases the cost and size. Therefore, in the technology disclosed in this specification, the welded portion is set to the outside of the seal ring when viewed in plan from a direction perpendicular to the cover plate. The case is formed with a groove that guides the refrigerant from the inner edge of the upper surface around the case toward the seal ring at a position facing the welding point across the seal ring when viewed from the direction perpendicular to the cover plate. To do. By adopting such a structure, when the refrigerant flows through the case, the refrigerant reaches near the seal ring near the welding point. Therefore, by welding while flowing a coolant through the case, the seal ring can be cooled during welding, and the seal ring can be prevented from being damaged by heat.

It is a disassembled perspective view of the cooler of an Example. It is the elements on larger scale of the part shown with the code | symbol A of FIG. It is a fragmentary sectional view explaining a welding process (manufacturing process). It is a typical perspective view of a welding apparatus (manufacturing apparatus). It is a figure explaining a modification.

  A cooler 10 according to an embodiment will be described with reference to the drawings. FIG. 1 is an exploded perspective view of the cooler 10. FIG. 2 is a partially enlarged view of a portion indicated by a symbol A in FIG. As shown in FIG. 1, the cooler 10 has a box shape. The cooler 10 is formed in a container shape, and the cover plate 2 is welded to the case 4 in which the coolant flows into the internal space S to seal the internal space S of the case 4. A refrigerant supply port 12 and a discharge port 13 are provided on one side surface of the case 4. In the internal space S of the case 4, a plurality of partition plates 8 for forming a refrigerant passage are provided. The refrigerant that has entered from the supply port 12 reciprocates in the case along the partition plate 8 and is discharged from the discharge port 13. The cooler 10 is used, for example, for cooling a semiconductor element by fixing a substrate on which a semiconductor element such as an IGBT having a large amount of heat generation is mounted on the cover plate 2.

  The case 4 and the cover plate 2 must be sealed so that the refrigerant does not leak. Therefore, a groove 6 that makes a round of the opening is provided in the upper surface 4a around the opening of the case 4, and a seal ring 7 is embedded in the groove 6 so as to make a round of the opening. The seal ring 7 is a ring made of, for example, silicon resin. The seal ring 7 may not be a solid that can maintain the ring shape. For example, silicon grease filled in the groove 6 or a curable resin filled in the groove 6 may be used.

  The case 4 and the cover plate 2 are joined by friction stir welding. A region indicated by a reference symbol Pc in FIG. 1 indicates a welding location (a planned welding location) in the cover plate 2. A region Ps shown in the case 4 so as to correspond to Pc indicates a welding location (scheduled welding location) on the upper surface 4 a around the opening of the case 4. As will be described later, the region Pc on the cover plate and the region Ps on the case are originally locations that are integrated by welding, but in order to help understanding in FIGS. Different symbols are used for cases. In FIGS. 3 and 5, the reference symbol P is attached to the joint where the welded part Pc of the cover plate 2 and the welded part Ps of the case 4 are integrated. Further, in FIG. 1, six welding locations are provided on the upper surface 4a around the opening, but the symbols Pc and Ps are attached to only one location, and other welding locations are provided so as not to complicate the drawing. It should be noted that there is no reference sign. In FIG. 1, the cover plate 2 is welded and joined in the form of dots at six locations on the upper surface 4 a around the opening of the case 4.

  In this cooler 10, the welding point (location indicated by symbols Ps and Pc in the figure) is located outside the seal ring 7 when viewed from the direction perpendicular to the cover plate 2 (Z-axis direction in the figure). To do. In addition, a groove 5 that guides the refrigerant from the inner edge 4b of the case peripheral upper surface 4a toward the seal ring 7 is formed in the opening peripheral upper surface 4a at a position facing the welding point Ps with the seal ring 7 interposed therebetween. This groove 5 is provided to guide the refrigerant filled in the internal space S of the case 4 to the vicinity of the seal ring 7 when the cover plate 2 is welded. In FIG. 1, reference numeral 5 is given to only one groove, but the grooves 5 are provided for all of the welding points Ps.

  FIG. 3 shows a state (cross section) during welding. In friction stir welding, a bar-shaped welding tool 31 with a thin tip is pressed against the surface of the cover plate 2 while rotating at high speed. If it does so, the contact location of the cover plate 2 will soften the location where the welding tool 31 was pressed by frictional heat. When the welding tool 31 is further pressed, the softening proceeds in the depth direction and the case 4 is softened. Thus, in the region indicated by the symbol P in FIG. 3, the material of the cover plate 2 and the material of the case 4 are mixed and integrated. That is, the cover plate 2 and the case 4 are joined. While the welding tool 31 is pressed, the coolant W continues to flow into the case internal space S. The refrigerant W is guided by the groove 5 and reaches the vicinity of the seal ring 7 to cool the seal ring 7. The cooling effect by the refrigerant W protects the seal ring 7 from heat generated by friction stir welding.

  In FIG. 4, the typical perspective view of the welding apparatus 30 is shown. It should be noted that only a part of the welding apparatus 30 is shown in FIG. The case 4 and the cover plate 2 are placed on the work table 44, and the cover plate 2 and the case 4 are pressed from above with a fixing jig 41, and the positions are fixed so that they do not shift. In this state, the welding tool 31 is pressed against the planned welding position while rotating at high speed. At this time, the refrigerant supply pipe 42 is connected to the supply port 12 of the case 4, and the refrigerant discharge pipe 43 is connected to the discharge port 13. Then, the refrigerant is supplied into the case 4 through the refrigerant supply pipe 42. The refrigerant flows along the partition plate 8 described above, and is then discharged out of the case through the refrigerant discharge pipe 43. Thus, the seal ring 7 is protected from the heat of welding by passing the coolant through the case during welding. When the welding of all the planned welding positions Pc is completed, the cover plate 2 is completely joined to the case 4. At this time, the boundary between the opening peripheral upper surface 4 a of the case and the cover plate 2 is sealed by the seal ring 7.

  With reference to FIG. 5, the modification of the groove | channel 5 provided in the surrounding upper surface 4a of case opening is demonstrated. 5A is a partial plan view of the case 4, FIG. 5B is a cross-sectional view taken along line BB in FIG. A, and FIG. 5C is C- in FIG. It is sectional drawing along C line. In addition, illustration of the cover plate 2 is abbreviate | omitted in FIG. 4 (A). In this modified example, two grooves 5 a and 5 b are provided to communicate from the case internal space S to the groove 6 in which the seal ring 7 is accommodated. In other words, when viewed in plan, a plurality of grooves 5a and 5b for guiding the refrigerant from the inner edge 4b of the upper surface around the case toward the seal ring 7 are located at positions facing the welding point P with the seal ring 7 interposed therebetween. Is formed. As described above, since the groove 5 is connected to the groove 6 in which the seal ring 7 is accommodated, the refrigerant W filled in the case space S reaches the periphery of the seal ring 7. Thereby, the seal ring 7 can be effectively cooled at the time of welding. Also, by providing a plurality of grooves, each groove can be made narrower in order to allow the same amount of refrigerant to flow as in the case of a wide single groove. By narrowing the groove, it is possible to prevent the seal ring 7 from protruding into the groove.

  Points to note about the technology shown in the examples will be described. The cooler may use a liquid (typically water) as a refrigerant, or may use a gas.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Cover plate 4: Case 4a: Upper surface around opening 4b: Edges 5, 5a, 5b: Groove 6: Groove (for sealing ring embedding)
7: Seal ring 8: Partition plate 10: Cooler 30: Welding device 31: Welding tool P: Welding spot Ps, Pc: Welding spot S: Case internal space W: Refrigerant

Claims (2)

A case for flowing refrigerant,
A seal ring embedded in the upper surface surrounding the case opening so as to go around the case opening;
A cover plate that covers the seal ring and is welded to the upper surface around the case opening at a plurality of points by friction stir welding;
When viewed in plan from a direction perpendicular to the cover plate,
The welding point is located outside the seal ring, and a groove that guides the refrigerant from the inner edge of the upper surface around the case opening toward the seal ring is formed at a position facing the welding point across the seal ring. Features a cooler.   The method for manufacturing a cooler according to claim 1, wherein friction stir welding is performed while flowing a coolant through the case.

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