JP5623270B2 - Brazing method and brazing structure - Google Patents

Description

  The present invention relates to a brazing method and a brazing structure for brazing two members constituting a cooler of a hybrid inverter (HV inverter).

  Conventionally, in order to braze two members constituting a cooler of an HV inverter, it is necessary to suppress deformation and displacement of each member during heating and melting. Therefore, conventionally, for example, as shown in FIG. 11, the cooler 31 includes a case 32, a cooling fin 33 provided in the case 32, a top plate 34 provided on the cooling fin 33, And an insulating substrate 35 fixed on the top plate 34. In order to temporarily fix the case 32 and the top plate 34, a large temporary fixing jig 40 has been used. The following Patent Document 1 describes an example of a brazing method using this type of temporary fixing jig. This type of temporary fixing jig is required to have heat resistance and rigidity, and has a complicated and expensive structure. In addition, the time for brazing heating and subsequent cooling takes as long as several tens of minutes to several hours, and the required number of temporary fixing jigs is increased depending on the number of products.

  Here, although the technical field is different from that of the HV inverter, the following Patent Document 2 describes a brazing method related to a heat exchanger such as an oil cooler of an internal combustion engine. In this brazing method, two members are temporarily fixed by laser welding, and then both members are brazed.

  Therefore, for the technical field of HV inverter coolers, like the heat exchanger of an internal combustion engine, the top plate 34 is temporarily fixed to the case 32 by laser welding, and then the case 32 and the top plate 34 are brazed. It is possible to do.

Japanese Patent Laid-Open No. 2001-129661 JP 2007-021555 A

  By the way, in the technical field of the cooler of the HV inverter, the case 32 and the top plate 34 constituting the cooler 31 are precision members, and a semiconductor element or the like is mounted on the insulating substrate 35 of the top plate 34. Precision and durability were required for joining the members.

  However, when the HV inverter cooler 31 is laser-welded for temporary fixing, there is a possibility that the case 32 and the top plate 34 which are members to be welded are deformed. That is, at the time of laser welding, thermal energy up to several tens of thousands of degrees C is applied to the case 32 and the top plate 34, heat shrinkage occurs in the case 32 and the top plate 34, and the case 32 and the top plate 34 depending on the depth of laser welding. There was a risk of distortion.

  In addition, as shown in a sectional view in FIG. 12, the case 32 and the top plate 34 are temporarily fixed by laser welding 37 before the case 32 and the top plate 34 are brazed with the brazing material layer 36 interposed therebetween. At this time, when the depth of the laser welding 37 exceeds the thickness of the brazing filler metal layer 36 and reaches the lower case 32, the flow of the molten brazing filler metal layer 36 changes due to the influence of the welding marks 38. There is a possibility that a defect (bonding failure) occurs at the bonding interface, or the case 32 and the top plate 34 are distorted by heat shrinkage as shown in the cross-sectional view of FIG. Further, since the deep welding mark 38 as shown in FIG. 13 is located at the tip of the case 32, there is a concern that the welding mark 38 may cause a crack due to the long-time use. It was.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent deformation of a member to be welded by laser welding and improve brazing quality for a cooler of an HV inverter. It is to provide a brazing method. Another object of the present invention is to provide a brazing structure capable of improving the durability of a member to be brazed.

  In order to achieve the above object, an invention according to claim 1 is a brazing method for brazing a first member and a second member constituting a cooler of an HV inverter, The second member is disposed on the first member via the brazing filler metal layer, and then the second member is laser-welded to the upper portion of the first member while limiting the depth of laser welding within the thickness range of the brazing filler metal layer. It is intended that the second member is brazed onto the first member by temporarily fixing the brazing material layer to heat and melting the brazing material layer.

  According to the configuration of the above invention, the laser welding depth for temporary fixing is limited within the range of the thickness of the brazing material layer, so that the laser welding does not reach the first member. Further, since the second member is temporarily fixed on the first member by laser welding, it is not necessary to use a jig for positioning the second member.

  To achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the depth of laser welding is controlled by adjusting at least one of the number of pulses and the output of the laser. The purpose is that.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1, the depth of laser welding can be easily controlled only by adjusting at least one of the number of pulses and the output of the laser.

In order to achieve the above object, a third aspect of the invention is a brazing structure in which a first member and a second member constituting a cooler of an HV inverter are brazed. the second member being brazed through a brazing material layer on only the second member of the first member and the second member, that the welding mark by laser welding is left in places The purpose.

  According to the configuration of the invention described above, the depth of the welding trace is located within the thickness range of the brazing filler metal layer, so that the deepest portion of the welding trace does not reach the first member.

  According to the first aspect of the present invention, when the first member, which is a precision member constituting the cooler, and the second member are brazed, the deformation of both members due to laser welding for temporary fixing is prevented. And brazing quality can be improved. Moreover, the structure for brazing can be simplified and brazed at low cost.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the depth of laser welding can be easily limited within the range of the thickness of the brazing material layer.

  According to the third aspect of the present invention, the precision member constituting the cooler can prevent the first member from cracking due to welding marks even when used for a long time. The durability after brazing can be improved for the first member.

The perspective view which concerns on one Embodiment and shows the cooler of an HV inverter. FIG. 2 is a cross-sectional view schematically showing a cross section taken along line AA of FIG. 1 showing the cooler according to the embodiment. Sectional drawing which expands and roughly shows the part of the chain line circle of FIG. 2 about a cooler concerning the embodiment. The flowchart which shows the procedure of the brazing method concerning the embodiment. The perspective view which shows the process of arrangement | positioning of the some insulated substrate to a top plate concerning the embodiment. The side view which concerns on the same embodiment and shows the process of welding the insulated substrate to a top plate. The perspective view which shows the process of arrangement | positioning a cooling fin, a top plate, etc. to a case according to the embodiment. The perspective view which concerns on the same embodiment and shows the process of the laser welding with respect to the several location on a top plate. Sectional drawing which shows the process of the laser welding of a top plate and a case concerning the embodiment. The graph which shows the relationship between a laser output and irradiation time concerning the embodiment. The partially broken side view which shows the mode of the temporary fixing of the cooler by a temporary fixing jig concerning a prior art example. Sectional drawing which shows the state by the laser welding of a case and a top plate concerning a prior art example. Sectional drawing which shows the distortion by the thermal contraction of the case and the top plate which were related to the prior art by laser welding.

  Hereinafter, an embodiment in which the “brazing method and brazing structure” in the present invention is embodied in a cooler of an HV inverter will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view of a HV inverter cooler 1. FIG. 2 is a schematic sectional view of the cooler 1 taken along the line AA of FIG. FIG. 3 is an enlarged schematic view of the portion of the chain circle S1 of FIG. The cooler 1 includes a case 2 as a first member formed in a box shape, a cooling fin 3 provided in the case 2, and a ceiling as a second member disposed on the cooling fin 3. A plate 4 and a plurality of insulating substrates 5 fixed on the top plate 4 are provided. Case 2 includes a flange 2a on the outer periphery. The top plate 4 is disposed so as to cover the cooling fins 3 and includes a flange 4a on the outer periphery thereof. The flange 4a of the top plate 4 is arranged in alignment with the flange 2a of the case 2 and is brazed.

  That is, as shown in FIG. 3, the flange 4 a of the top plate 4 and the flange 2 a of the case 2 are joined via the brazing material layer 6. Further, weld marks 7 by laser welding remain on the flange 4a of the top plate 4 in some places. This welding mark 7 is a mark by laser welding when the top plate 4 is temporarily fixed to the case 2 before brazing, and the depth thereof falls within the thickness range of the brazing material layer 6. Yes. In this embodiment, the thickness TK1 of the flange 2a of the case 2 is "3.0 (mm)", the thickness TK2 of the flange 4a of the top plate 4 is "0.6 (mm)", and the thickness TK3 of the brazing material layer 6 is “0.15 (mm)”, and the diameter D1 of the weld mark 7 is “1-2 (mm)”. In this embodiment, the brazing structure of the present invention is configured for the cooler 1 described above.

  Here, the brazing method of the brazing structure according to the above-described cooler 1 will be described. FIG. 4 is a flowchart showing the procedure of the brazing method of this embodiment.

  First, as shown in FIG. 4 (1), a plurality of insulating substrates 5 are welded to the top plate 4. That is, as shown in a perspective view of FIG. 5, a plurality of insulating substrates 5 are arranged in the recesses 4b of the top plate 4, and as shown in FIG. Laser welding is performed with a fiber laser device 21.

  Next, as shown in FIG. 4B, the top plate 4, the cooling fin 3, the case 4, and the like, to which the insulating substrate 5 is welded, are assembled together. That is, as shown in FIG. 7, the cooling fin 3 is disposed in the recess 2 b of the case 2, and the top plate 4 is disposed on the cooling fin 3. At this time, as shown in FIGS. 2 and 3, the flange 2a of the case 2 and the flange 4a of the top plate 4 are combined, and a brazing material layer 6 having a predetermined thickness TK3 is provided therebetween.

  Next, as shown in FIG. 4 (3), the top plate 4 is temporarily fixed to the case 2 by laser welding. That is, as shown in a perspective view of FIG. 8, laser welding is performed by a fiber laser device 21 at a plurality of locations on the flange 4 a of the top plate 4. At this time, the depth of laser welding is controlled within the range of the thickness TK3 of the brazing filler metal layer 6, as shown in the sectional view of FIG. In this embodiment, the fiber laser device 21 irradiates the welding point by dividing the laser into a plurality of pulses.

  FIG. 10 is a graph showing the relationship between the laser output and the irradiation time. As shown in FIG. 10, in this embodiment, the laser beam is divided into three pulses and irradiated to the welding point. Each pulse output has a uniform rise time Tu1, Tu2, Tu3, thereafter, the peak times Tp1, Tp2, Tp3 are controlled, and the fall times Td1, Td2, Td3 are controlled. Therefore, the irradiation time of each pulse output is determined by adding the variable peak times Tp1 to Tp3 and the variable falling times Td1 to Td3 to the rising times Tu1 to Tu3, respectively. In this embodiment, the total laser output to the welding point is controlled by controlling the number of pulses of the laser, the irradiation time of each pulse output, or the peak output of the laser. By this output control, the depth of laser welding is controlled.

  Thereafter, the top plate 4 is brazed to the case 2 as shown in FIG. That is, the temporarily fixed top plate 4 and the case 2 (assemblies of the cooler 1) are put into a welding furnace, and the flange 4a of the top plate 4 and the flange 2a of the case 2 are brazed. As a result, a brazed cooler 1 as shown in FIG. 1 is obtained.

  As described above, in the brazing method of this embodiment, when the case 2 and the top plate 4 constituting the cooler 1 of the HV inverter are brazed, the top 2 is placed on the flange 2 a of the case 2 via the brazing material layer 6. The flange 4a of the plate 4 is arranged, and then the flange 4a of the top plate 4 is temporarily mounted on the flange 2a of the case 2 by laser welding while limiting the depth of laser welding within the range of the thickness TK3 of the brazing material layer 6. Then, the flange 4a of the top plate 4 is brazed on the flange 2a of the case 2 by heating and melting the brazing material layer 6.

  According to the brazing method of this embodiment described above, the laser welding depth for temporary fixing is limited within the range of the thickness TK3 of the brazing material layer 6, so that the influence of laser welding is affected by the case 2. It does not extend to the flange 2a. For this reason, when the case 2 and the top plate 4 which are precision members constituting the cooler 1 are brazed, the case 2 and the top plate 4 can be prevented from being deformed by laser welding for temporary fixing. Quality can be improved. As a result, the durability after brazing can be improved for the case 2 which is a precision member constituting the cooler 1.

  Further, according to the brazing method of this embodiment, the flange 4a of the top plate 4 is temporarily fixed on the flange 2a of the case 2 by laser welding. It is not necessary to use the temporary fixing jig 40 as in the example. For this reason, the structure for brazing can be simplified and brazed cheaply.

  Further, according to the brazing method in this embodiment, the depth of laser welding can be easily controlled only by adjusting at least one of the number of pulses and the output of the laser from the fiber laser device 21. For this reason, the depth of laser welding can be easily limited within the range of the thickness TK3 of the brazing filler metal layer 6.

  Furthermore, according to the brazing structure of this embodiment, since the depth of the weld mark 7 is located within the range of the thickness TK3 of the brazing material layer 6, the deepest part of the weld mark 7 extends to the flange 2a of the case 2. There is no. For this reason, even if it uses for a long time, it can prevent that the crack 2 is generated in the flange 2a of the case 2 by the weld mark 7 as a trigger. Also in this sense, the durability after brazing can be improved for the case 2 that is a precision member constituting the cooler 1.

  In addition, this invention is not limited to the said embodiment, A part of structure can also be changed suitably and implemented in the range which does not deviate from the meaning of invention.

  For example, in the above embodiment, the present invention is embodied when the case 2 and the top plate 4 constituting the cooler 1 are brazed. However, the present invention is also embodied when the case and the cooling fin are brazed. Can do.

  The present invention can be used for a HV inverter cooler and its manufacture.

1 Cooler 2 Case (first member)
2a Flange 3 Cooling fin 4 Top plate (second member)
4a Flange 6 Brazing material layer 7 Weld mark TK3 Thickness (of brazing material layer)

Claims (3)

A brazing method for brazing a first member and a second member constituting a cooler of an HV inverter,
Disposing the second member on the first member via a brazing filler metal layer,
Thereafter, the second member is temporarily fixed on the first member by the laser welding while limiting the depth of laser welding within the range of the thickness of the brazing material layer,
Thereafter, the second member is brazed onto the first member by heating and melting the brazing material layer.   The brazing method according to claim 1, wherein the depth of the laser welding is controlled by adjusting at least one of the number of pulses and the output of the laser. A brazing structure in which a first member and a second member constituting a cooler of an HV inverter are brazed,
The second member is brazed onto the first member via a brazing material layer, and only the second member of the first member and the second member is welded by laser welding. brazed structure, characterized in that marks are left in places.

Images