Gm Global Technolgoy Operations, Inc.

S. a. Day Manufacturing Co., Inc.

Other

Gary A Halstead

Brian L Barten

Richard P Ryan

Shrikant M Joshi

David M Smith

Ronald C Treloar

Paul J Conn

Glenn W Shaffer

Gregory R Smith

Michael J Irish

Terence Trentacoste

An improved method is provided for producing an aluminum tube of the type used as cooling tubes for heat exchangers, and particularly automotive heat exchangers. The method utilizes a flux-containing composition that can be selectively deposited in a manner that permits the manufacture of aluminum tubes having a lockseam construction. As a result, the method made possible by this invention provides for the manufacture of heat exchanger tubes that offer the weight, durability and safety advantages of aluminum alloy construction, but at lower investment, processing and material costs as compared to prior art welded aluminum tubes. Another advantage of the present method is that minimal amounts of braze alloy and flux are required, yet uniform and consistent brazed joints can be produced to yield leak-proof brazed assemblies.

Method for forming aluminum tubes and brazing a lockseam formed therein

A high capacity condenser for automotive application is built up from two layers or modules so as to make maximum use of standard components. The tanks of header tank and tube type condensers are extruded with interfitting clearance notches and stand-off flanges along the length of the tanks that maintain the two modules spaced apart and aligned. A specially designed cross-over pipe interconnects the two modules in a fluid sense and also cooperates in mechanically joining the two.

High capacity automotive condenser

A headered tube and type condenser for automotive applications has a pair of tanks with side walls that face the ends of the tubes, and flat face walls perpendicular thereto. After installation, the tank face walls face the vehicle radiator. The ends of the tubes extend partially into the tanks, and have a predetermined spacing from the side walls of the tank, A fitting, either inlet our outlet or both, is secured to the face wall of either or both tanks. The portion of the fitting that extends into the tank has a smaller width than the predetermined spacing, and so can be placed anywhere along the entire length of the face wall without hitting the ends of the tubes.

Face plumbed condenser for automotive air conditioner

A braze furnace of the inert gas type cooperatively uses the waste heat from the cooling chamber to vaporize liquid inert gas, while using the coolness of the inert gas being vaporized to accelerate the cooling process itself. The walls of the cooling chamber provide a hollow plenum into which stored liquified inert gas is metered and vaporized. From the plenum, vaporized gas is routed wherever needed to purge oxygen from the system. In addition, liquid gas can be injected directly into the cooling chamber for even quicker, direct part cooling and the purge the cooling chamber.

Braze furnace with improved inert gas system

A muffle furnace assembly for brazing aluminum heat exchanger workparts comprises a tubular muffle having a workpart conveyer extending therethrough. A pair of fans disposed inside the muffle circulate high temperature atmosphere through the workparts. The muffle is surrounded by an insulative outer shell spaced to form an interstitial cavity therebetween. High temperature combustion gasses are directed into the interstitial cavity and flow in a helical path about the muffle. Louvers are provided in the muffle, between the workparts and the fans, for regulating the amount of inert gas flow within the muffle. Inlet and exit vestibules usher workparts into and out of the furnace assembly to minimize oxygen contamination within the muffle.

Aluminum heat exchanger braze furnace

The brazing process for an aluminum headered condenser is improved by adding a flux drying and preheating process that both dries the wet flux layer and prepares the part for more efficient brazing. An oven is divided into two directly connected zones, one that dries the flux layer at a lower temperature, and one that preheats the condenser at a higher temperature that is still too low to melt the flux layer. Both the tanks and the core of the condenser are heated hotter than they would be if they were only flux dried, although the core is heated significantly more. The preheated parts are then transported to the braze furnace indirectly, through ambient, which serves to cool the core more than the tanks, to a temperature lower than the tanks. Finally, the part is run through a normal braze cycle. Because the tanks begin hotter than normal, they reach braze melt temperature sooner than they normally would. Because the core starts out cooler than the tanks, they reach braze temperature closer in time to the tanks.

Aluminum heat exchanger brazing method and apparatus

A heat exchanger apparatus includes a pair of tank units for containing a fluid, such as an engine coolant, or freon, each including a header having a plurality of slots for receiving a plurality of parallel fluid flow tubes in fluid communication between the tanks. Air centers are connected between the parallel fluid flow tubes for directing an inlet air stream of the vehicle. Side plates are secured between the ends of the headers to protect and provide rigidity to the heat exchanger. Interlocking members are provided between the headers and sideplates for interlocking same to one another during the brazing process.

Heat exchanger sideplate interlocked with header

An improved method for assembling a brazed heat exchanger unit suitable for use in an automobile air conditioning system. Prior to assembly, a sufficiently viscous flux-brazing composition is selectively applied to the internal and external features of the heat exchanger which serve as the joining surfaces of the heat exchanger. The flux-brazing composition is specifically applied to the internal surfaces of the aluminum alloy header and the external surfaces of the tubes so as to form uniformly and consistently brazed internal and external joints. The flux-brazing composition of this invention consists of potassium tetrafluoroaluminate particles, an aluminum-silicon powder, zinc and a binder. The flux-brazing composition enables the selective application of both a flux compound and a brazing compound, eliminating excessive use of flux and eliminating the need to clad the components of the heat exchanger with an aluminum alloy brazing material.

Method for forming heat exchangers

A heat exchanger apparatus includes a pair of tanks with parallel tube passes and air centers connected therebetween for cooling the engine fluid, such as a coolant, by the air intake stream to the vehicle. The tanks are formed by an extrusion forming three sides thereof and a header is brazed thereto for forming the fluid chamber in the tanks. The extrusion includes a die formed pocket therein to receive the sides and one end of a partition member and the second end of the partition member is curved to abut the header. The curved second end has flanged ears therein that seat in segments of the die formed pocket which are laterally outwardly of spaced sides segments of the pocket to position the partition within the pocket so that an outer surface thereon will be positioned against a header to form a braze seal between the partition and both the header and the extruded tank.

Extruded tank pocket design for separator

A heater of a vehicle includes a pair of tank units with fluid tube passes and air centers formed therebetween. The tank units include a separate tank extrusion and header. The tank extrusion comprises a generally U-shaped extrusion with recesses provided on the exterior side of the side walls of the U-shaped extrusion. A mounting flange extends from one side wall of each tank extrusion. The header includes deformable tabs which extend over the recesses to allow clinching of the header to the tank extrusion. The mounting flanges slide within notches of a plastic case in the air module for sealing and securing the heater to the module.

Slide mounted heater assembly

A convection braze furnace for brazing aluminum heat exchangers in an inert gas rich atmosphere includes entrance and exit vestibules forming atmosphere barriers of suspended stainless steel strips. The interior of the braze furnace is divided into multiple zones for progressively heating the heat exchangers to a brazing temperature and then cooling the heat exchangers in the final zone. An impeller circulates the heated intent gas atmosphere within each zone to accelerate heat transfer. A chain type conveyor supports the heat exchangers as they are moved through the braze furnace. An isolated return tube surrounds the lower return side of the conveyor chain as it passes through the braze furnace. The braze furnace housing is comprised of inner and outer shells having an inert gas pressurized interstitial cavity therebetween. The inner shell includes a plurality of expansion strips having generally ellipsoidal corner expansion joints.

Method and apparatus for convection brazing of aluminum heat exchangers

A combination radiator and condenser apparatus has a pair of extruded tank and header assemblies adapted to be connected in both a coolant system for liquid cooled engine and a refrigerant system of an automobile air conditioning system. The assemblies each include an extruded tank with two chambers separated by an internal partition which extends the full height of the tank. Each extruded tank further includes a slotted wall for receiving the ends of a plurality of unitary extruded fluid flow tubes extending between each extruded tank. Each of the unitary extruded fluid flow tubes has first and second passages therein connected respectively to the coolant chamber and the high pressure refrigerant chamber of each of the extruded tanks. An open-sided gap or channel extends within the partition and the length of the tank for reducing heat conduction between the coolant and refrigerant. The channel is open through a longitudinal wall of the extruded tank.

Combination condenser and radiator tank thermal gap

A combination radiator and condenser apparatus has a pair of tank and header assemblies adapted to be connected in both a coolant system for liquid cooled engine and a refrigerant system of an automobile air conditioning system. The assemblies each include a tank with two compartments separated by an internal partition which extends the full height of the tank. Each tank includes a slotted header for receiving the ends of a plurality of unitary extruded fluid flow tubes extending between each extruded tank and each of the unitary extruded fluid flow tubes have first and second passages therein connected respectively to the coolant chamber and the high pressure refrigerant chamber of each tank. Each tank includes a unitary tank extrusion and separate header assembly connected thereto. The tank extrusion includes a pair of side walls with the partition therebetween. A first embodiment of the header assembly includes two separate headers extending between the respective side wall and partition within grooves thereof. A second embodiment includes a single header extending between the side walls with a slot in the center to receive locking tabs extending from the partition.

Extruded coolant/refrigerant tank with separate headers

A heat exchanger apparatus includes first and second parallel tank units with a core of parallel tube passes and air centers extending therebetween for cooling the fluid in the tanks and flowing through the tube passes. The first tank unit includes an integral main tank and outlet tank. The main tank is connected to an inlet fitting for receiving refrigerant vapor and is in fluid communication with the tube passes. The outlet tank is parallel with the main tank and spaced from the tube passes and includes the outlet fitting for directing the high pressure refrigerant liquid to the evaporator of a refrigerant system in an automotive air conditioning system and an aperture between the main tank and outlet tank supplies refrigerant from the core to the outlet tank.

Extruded tank condenser with integral manifold

A condenser having two piece die formed condenser tube parts that are joined along a beveled outer edge. The tube material is braze cladded on both sides for corrosion resistance and for high quality internal braze bonding of (1) longitudinal tube webs for optimizing burst strength, and (2) the tubes to associated air centers which are not cladded for an economical unit. The tubes can be readily made in a multiport or single port design by die forming the longitudinal webs in each tube part, and at discreet lengths along the tube length to provide a cut off area for sizing the tube and a smooth circumferential area where the tube parts with a beveled outer edge enter the header providing a close fit and high quality brazed joints. This tube design provides material and cost advantages over the conventional extruded tubes or roll formed condenser tubes and is readily fabricated using corrosion resistant alloys providing long service life. The number and spacing of the webs in this construction can be readily made by changing the spacing of the dies for forming the tube parts. The method provided by this invention provides increased output with higher machine speeds as compared to extrusion type processes.

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Lockport, NY, United States of America

Gary A Halstead