Cooling air circuits for welding machine

[0002] 1. Field of the Invention

[0003] This invention pertains to electric arc welding power sources or machines, and more particularly to cooling tungsten inert gas (TIG) welding machine power supplies.

[0004] 2. Description of the Prior Art

[0005] It is well known that the power supplies of electric arc welding machines, including tungsten inert gas (TIG) welding machines, generate considerable amounts of heat. To assure continuous and proper operation, the heat must be removed from the power supplies. For that purpose, various types of air cooling designs have been developed. For example, U.S. Pat. No. 5,831,240 shows a welding machine power supply having end panels with louvers in them. A fan next to one of the louvers blows air through the power supply from one end panel to the other. Some of the cooling air passes through a heat sink to which several major heat generating components are mounted. A deficiency of the design of the Pat. No. 5,831,240 is that much of the cooling air does not flow through the heat sink. Thus, maximum efficiency is not attained for cooling the major heat generating components. In addition, dirty air is blown over delicate electronic components.

[0006] U.S. Pat. No. 5,642,260 describes a welding machine having an air tunnel between the two ends of the power supply housing. A fan at one end of the tunnel blows air through the tunnel. Some heat generating components are inside the tunnel. Others are located outside the tunnel but are mounted to two heat sinks that are inside the tunnel. The air flowing through the tunnel directly cools the heat generating components that are inside the tunnel. The cooling air also directly cools the heat sinks inside the tunnel and thus indirectly cools the-heat generating components that are outside the tunnel but that are mounted to the heat sinks. Components of the power supply that are neither in the tunnel nor mounted to the heat sinks are in a dead space, i.e., they are not directly cooled at all.

[0007] The Lincoln Electric Company of Cleveland, Ohio, markets an arc converter that includes a fan between two ends of a housing. The fan draws air into the housing from both sides of the housing and pushes the air through a tunnel and out one end of the housing. Both a heat sink and heat generating components are present in the tunnel. The cooling air directly cools the components inside the tunnel and indirectly cools the components mounted to the heat sink outside the tunnel.

[0008] Despite the various cooling systems incorporated into prior welding machine power supplies, there nevertheless is room for improvements to them.

[0009] In accordance with the present invention, cooling circuits for electronic equipment is provided that efficiently cools both major and minor heat generating components. This is accomplished by a counterflow circuit that cools the minor heat generating components in addition to a primary circuit that cools major heat generating components.

[0010] The primary circuit extends between upstream and downstream ends of a housing. A first chamber at the housing upstream end contains some minor heat generating components. Other minor heat generating components are located within the housing but outside of the primary circuit.

[0011] There is a second chamber at the housing downstream end. A fan divides the first and second chambers. The second chamber has a periphery that is aligned with the fan such that all the cooling air blown by the fan flows through the second chamber along the primary circuit. According to one aspect of the invention, the second chamber periphery next to the fan is composed of center and side walls of two symmetrically arranged heat sinks. All the air blown by the fan flows through the two heat sinks. In a preferred embodiment, the first heat sink reaches between the fan and the primary circuit downstream end. First major heat generating components are mounted to the first heat sink outside of the second chamber. Second major heat generating components are mounted to the second heat sink outside of the second chamber. There is a wind tunnel between the second heat sink and the primary circuit downstream end that contains third major heat generating components.

[0012] Operation of the fan draws cooling air through the housing upstream end into the first chamber of the primary curcuit. The fan blows the air through the second chamber and out the housing downstream end. The cooling air thus has a negative pressure in the first chamber and a positive pressure in the second chamber.

[0013] The cooling air directly cools the minor heat generating components in the first chamber. The cooling air further cools the heat sinks in the second chamber, which in turn cool the major heat generating components mounted to the heat sinks outside the second chamber. Finally, the cooling air in the primary circuit directly cools the major heat generating components in the wind tunnel.

[0014] It is a feature of the invention that the minor heat generating components outside the primary circuit are cooled by means of the fan along with the heat generating components associated with the primary circuit. Cooling the minor heat generating components and more delicate electronic components outside the primary circuit is achieved by the counterflow circuit. The counterflow circuit extends between the housing downstream end and the first chamber of the primary circuit. The negative pressure in the first chamber draws cooling air into the first chamber from the counterflow circuit, and into the counterflow circuit through the housing downstream end. The cooling air in the counterflow circuit flows parallel to but in the opposite direction as the air in the primary circuit. The air of the counterflow circuit enters the first chamber from its sides, where it mixes with the air in the primary circuit arriving through the housing upstream end. The fan blows the mixed cooling air in the downstream direction through the primary circuit second chamber. Thus, all the air under positive pressure from the fan flows through the second chamber. The temperature of the air entering the fan is only slightly above ambient, because only the minor heat generating components are cooled by the air in the counterflow circuit and by the air in the primary circuit first chamber. Accordingly, maximum cooling capacity is available to the air in the primary circuit second chamber. The air flowing past the heat sinks and through the wind tunnel provides adequate cooling for the major heat generating components mounted to the first and second heat sinks and for the major heat generating components located in the wind tunnel.

[0015] Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention.

[0016] FIG. 1 is a perspective view of a welding machine power supply that includes the present invention.

[0017] FIG. 2 is an exploded view showing the major sub-assemblies of the welding machine power supply of FIG. 1.

[0018] FIG. 3 is a perspective view of a first side of the power supply with the top cover removed.

[0019] FIG. 4 is a view similar to FIG. 3, but showing some electronic components removed.

[0020] FIG. 5 is a perspective view of a second side of the welding machine power supply.

[0021] FIG. 6 is an exploded perspective view of the second chamber of the welding machine power supply.

[0022] FIG. 7 is a perspective view of the second chamber of the primary circuit in its assembled condition.

[0023] Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention, which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto.

[0024] Referring to the drawings, an electronic power supply 1 is illustrated that includes the present invention. The particular power supply 1 shown is for a tungsten inert gas (TIG) welding machine. However, it will be appreciated that the invention is not limited to welding applications.

[0025] The power supply 1 is comprised of a base 2, a front end panel 3, and a back end panel 5. The front end panel 3 has louvers 7, and the back end panel 5 has similar louvers 9. A top cover 10, having an inverted U-shape, is assembled to the end panels and the base, such as by fasteners not illustrated in the drawings that engage holes 16 in the base 2. The base, end panels, and top cover 10 cooperate to create an interior space of the power supply 1.

[0026] In accordance with the present invention, a vertical wall 11 upstands from the base 2 between the two end panels 3 and 5. The vertical wall 11 is the full width of the base and the cover 10. The vertical wall has a large opening 12. A horizontal wall 13 connects the upper end of the vertical wall to the front end panel. As illustrated best in FIG. 2, the horizontal wall 13 has tabs 14 that abut the front end panel. The tabs 14 aid in connecting the horizontal wall to the front end panel by fasteners not shown. The top cover 10 cooperates with the base, vertical wall, horizontal wall 13, and the front end panel to define a magnetics chamber 15. There are openings, such as those represented at reference numerals 17, in the vertical wall, and there are similar openings 19 in the horizontal wall.

[0027] Located in the power supply magnetics chamber 15 are a number of electronic components, each of which generates only a minor amount of heat during operation of the welding machine 1. Examples of the minor heat generating components include a coupling coil 21, output inductor 23, transformer 25, and spark gap and high frequency board 27.

[0028] Attached to the vertical wall 11 over the opening 12 and outside of the magnetics chamber 15 is a motor driven fan 29. In the preferred embodiment, a first flange of the fan 29 is attached to the vertical wall by screws 31, FIG. 3.

[0029] Also joined to the vertical wall 11 is an upper heat sink 33. Joining of the upper heat sink 33 to the vertical wall is by an inner bracket 35. A top leg 37 of the inner bracket 35 overlies and is joined to a center wall 39 of the upper heat sink. The inner bracket overhangs the front end 41 of the upper heat sink. Tabs 43 on the inner bracket are used to join it to the vertical wall. The overhang of the inner bracket relative to the upper heat sink front end 41 is such that a second flange 45 of the fan 29 fits snugly against the upper heat sink front end 41. That is, the fan is sandwiched between the upper heat sink and the vertical wall. The second end 47 of the upper heat sink is joined to the power supply back end panel 5 by an outer bracket 49. There is thus a firm structural connection between the end panels 3 and 5 by means of the horizontal wall 13, vertical wall 11, inner bracket, upper heat sink, and outer bracket 49.

[0030] In addition to the center wall 39, the upper heat sink 33 also has two side walls 51. At the free end of each side wall 51 is a C-shaped channel 53. Between and parallel to the upper heat sink side walls are multiple fins 55, which are integral with the center wall 39.

[0031] A lower heat sink 57 has a center wall 59 and side walls 61. The side walls 61 terminate in respective C-shaped channels 63. There are multiple fins 65 parallel to and between the lower heat sink side walls and integral with the center wall 59.

[0032] To hold the heat sinks 33 and 57 to each other, a pair of rails 67 is used. The rails 67 have upper and lower tongues 69 that slide into the channels 53 and 63 of the upper and lower heat sinks, respectively. The front ends 70 of the rails abut the vertical wall 11. The rails are fastened to the vertical wall by fasteners, not shown, that engage holes 72 in the rail ends 70. In that manner, the lower heat sink is suspended from the upper heat sink. It will be noticed that the lower heat sink is approximately one-half as long as the upper heat sink.

[0033] In the illustrated construction, there is a wind tunnel 73 between the back end 71 of the lower heat sink 57 and the back end panel 5. The wind tunnel 73 is in the form of a U-shaped bracket having a center leg 75 and upstanding side legs 77. The free ends of the side legs 77 are secured to the rails 67 by fasteners 79. The wind tunnel is electrically isolated from the lower heat sink by insulation strips 81.

[0034] The walls 39 and 51 of the upper heat sink 33 and the walls 59 and 61 of the lower heat sink 57 define the periphery of a second chamber 82 that is on the opposite side of the fan 29 as the magnetics chamber 15. The wind tunnel legs 75 and 77 cooperate with the walls of the upper heat sink to define the periphery of the second chamber 82 adjacent the back end panel 5.

[0035] Mounted to the outside of the center wall 39 of the upper heat sink 33 is an input rectifier, boost converter, and half-bridge invertor shown collectively at reference numeral 83. Those components generate considerable heat during operation of the welding machine power supply 1. Other major heat generating components include diodes, rectifiers, and a snubber inductor collectively represented at reference numeral 85 and mounted to the center wall 59 of the lower heat sink 57. Another major heat generating component is an input inductor 87 inside the wind tunnel 73. During operation of the power supply 1, only small amounts of heat are generated by the components 21, 23, 25, and 27 in the magnetics chamber 15. On the other hand, considerable heat is generated by the components 83, 85, and 87. Heat from the components 83 is conducted to the upper heat sink 33, and heat from the components 85 is conducted to the lower heat sink 57.

[0036] Operation of the fan 29 creates a negative air pressure in the magnetics chamber 15. Consequently, cooling air is drawn in a downstream direction 89 into the magnetics chamber through the louvers 7 in the front end panel 3. The cooling air cools the minor heat generating components 21, 23, 25, and 27 in the magnetics chamber. The cooling air is warmed only slightly as it flows through the magnetics chamber to the fan.

[0037] It is a feature of the invention that the periphery of the second chamber 82 is arranged relative to the fan 29 such that all of the air blown by the fan flows through the second chamber; none of the air flows around the outsides of the heat sinks 33, 57 or the wind tunnel 73. Specifically, all the air flows past the fins 55 and 65 of the upper and lower heat sinks 33 and 57, respectively, which cools the fins and therefore the major heat generating components 83 and 85. The cooling air also passes over the input inductor 87 to cool it.

[0038] From the second chamber 82, the cooling air flows out the louvers 9 in the back end panel 5. It is thus seen that there is a primary circuit 91 for the cooling air that extends from the front end panel 3, through the magnetics chamber 15, and through the second chamber 82 to the back end panel 5. All the cooling air in the primary circuit 91 flows in the downstream direction 89.

[0039] Further in accordance with the present invention, electronic components in the power supply 1 other than those cooled by the air flowing in the primary circuit 91 are also cooled. Looking especially at FIGS. 2, 3, and 5, there are a number of electronic components 93 inside the power supply 1 but outside of the primary circuit and not mounted to either heat sink 33 or 57. Although the components 93 do not generate major amounts of heat, it is nevertheless beneficial to cool them.

[0040] It will be noticed in FIGS. 4 and 5 that the heat sinks 33 and 57 and the wind tunnel 73 do not take up the full width of the power supply 1. Rather, there is a distance D between the side walls 51 and 61 of the upper and lower heat sinks, respectively, and the side edges 95 of the back end panel 5. Consequently, when the top cover 10 is in place, there are spaces 97 inside the power supply between the two sides of the top cover and the associated sides of the second chamber 82. The spaces 97 are open to atmospheric air through the louvers 9 in the back end panel.

[0041] As described previously, operation of the fan 29 causes cooling air to flow in the downstream direction 89 through the primary circuit 91. At the same time, the negative-pressure in the magnetics chamber 15 draws air from the spaces 97 through the openings 17 in the vertical wall 11 and through the openings 19 in the horizontal wall 13 into the magnetics chamber. Consequently, a counterflow circuit 99 is created from the louvers 9 in the back end panel 5 to the magnetics chamber. The flowing cooling air in the counterflow circuit 99 flows past and cools the electronic components 93. The air from the counterflow circuit mixes with the air in the primary circuit in the magnetics chamber. The mixed air flows in the downstream direction 89 from the fan 29 through the second chamber 82. Since the components 93 produce only minor amounts of heat, the cooling air entering the second chamber is cool enough to efficiently cool the heat sinks 33, 57 and the inductor 87 in the wind tunnel 73.

[0042] Thus, it is apparent that there has been provided, in accordance with the invention, cooling circuits for a welding machine power supply, including a TIG welding machine power supply, that fully satisfy the aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.