Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Reexamination Certificate
1999-05-17
2001-01-16
Leo, Leonard (Department: 3743)
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
C029S890054, C165S148000, C165S165000, C165S173000, C165S175000, C165S178000
Reexamination Certificate
active
06173493
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a modular heat exchanger wherein each of the core modules is formed from a unitary block of extruded heat exchange material and, in particular, to a heat exchanger that provides enhanced beat dissipation and to a method of making the same using an all-welded construction.
Typically, conventional of heat exchangers for use in automobiles utilize heat exchanging core elements which include a series of generally parallel tubular conduits extending between and attached at their opposite ends to inlet and outlet headers. The tubular conduits are provided with heat conducting and dissipating fins which may be either of a flat plate or serpentine construction, and which are soldered or brazed to the tubular conduits. The conduits, in turn, are soldered or brazed to the headers or to similar fluid accumulating tanks.
The rigid soldered or brazed joints have always constituted a common source of heat exchanger failure and, when the heat exchangers are used in automotive applications, usually require removal of the entire radiator for repair, thereby resulting in down time for the automotive equipment. Thus, there has been a long need and desire for both a heat exchanger having unitary core elements and for one in which braised or soldered connections can be minimized and, preferably, eliminated completely.
U.S. Pat. No. 5,303,770 discloses a modular heat exchanger which includes unitary finned tubular core elements which can be assembled into a multi-module heat exchanger, including flow distributing headers or end tanks without brazed, soldered, or welded connections of any kind. The heat exchanger is fully disassemblable in one embodiment, however, mechanical connectors and a substantial number of o-ring seals are required for assembly. In another embodiment, welded or braised connections may be utilized to provide units which are partially disassemblable. However, these units are potentially subject to the prior art problems of inadequate joint strength and environmentally less desirable materials.
U.S. Pat. No. 5,383,517 discloses a modular heat exchanger having unitary finned tubular core elements which can be assembled without any braised, soldered or welded connections or mechanical connectors. The modules are formed from extruded aluminum blocks into which heat exchanging fins are cut or cold formed. Flow accumulating passages are bored into the ends of the modules. The modules are assembled with a high strength adhesive sealant which simultaneously secures the modules together and seals the peripheries of the bore adhesive sealant which simultaneously secures the modules together and seals the peripheries of the bore passages at the module interfaces. However, it has been found during certain applications, increased heat dissipation by the heat exchanging fins is necessary.
It is an object and feature of the present invention to provide a modular heat exchanger with increased heat dissipating ability.
It is a further object and feature of the present invention to provide a modular heat exchanger wherein the modules may be formed from extruded aluminum blocks in to which the heat exchanging fins are cut.
It is a particular object of the present invention to provide such a heat exchanger which utilizes all aluminum components and an all-welded construction.
SUMMARY OF THE INVENTION
In accordance with the method of the present invention, a modular heat exchanger is made by the steps of (1) extruding a rectangular cross section tube which has a longitudinal through bore and opposite faces having parallel longitudinal grooves; (2) cutting parallel slots in the opposite faces which slots are transverse to and extend into the longitudinal grooves to form a pattern of thin toothed fins between opposite unslotted grooved face portions; and (3) welding two of the tubes together in face-to-face relation with welds that fill the abutting grooved face portion. The method preferably also includes the step of welding a tank to the joined tubes to enclose the through bores at the ends of the tubes.
Preferably, the longitudinal grooves formed in the extruding step have V-shaped cross sections. The cutting step comprises cutting the slots to a depth at least equal to the depth of the grooves and, preferably, to a depth greater than the depth of the grooves. In the extruding step, the through bore is preferably formed with a plurality of longitudinally extending ribs.
A variant method for making an all-welded aluminum heat exchanger in accordance with the present invention comprises the steps of: (1) cutting a plurality of equal length tubes from an aluminum extrusion having a rectangular cross section, a longitudinal through bore and longitudinally V-grooved opposite faces; (2) cutting parallel slots in said faces transverse to the grooves to form a plurality of thin parallel toothed fins between opposite unslotted V-grooved face portions; (3) welding pairs of said tubes together in face-to-face relation with aluminum welds that fill the abutting V-grooved face portions to form a heat exchanger core; and, (4) welding an aluminum tank to each end of the core with aluminum welds to enclose the through bores at the ends of the core. The method preferably includes the additional steps of forming a fluid inlet opening in one of said tanks, and forming a fluid discharge opening in the other of said tanks. The method may also include the step of welding respective inlet and outlet pipes to said inlet and outlet openings.
An all-welded heat exchanger of the present invention comprises a plurality of rectangular cross section tubes, each of which has a longitudinal through bore and opposite faces having parallel longitudinal grooves. The faces are provided with parallel slots that extend across the faces transversely to and through the grooves to define thin toothed fins between unslotted grooved face portions. Welded connections are provided to join pairs of tubes in face-to-face relation, the welded connections filling the ends of the grooves in the abutting grooved face portions. A tank is welded to enclose the through bores at the ends of the joined tubes. The tank preferably includes a peripheral edge along which welded seams join the tank to the periphery of the ends of the joined tubes. The tank includes a fluid opening and a fluid transfer pipe is attached to the opening with a welded joint. In the preferred construction, the tubes, and the welded connections, seams and joints are all made of aluminum.
The modified construction of a modular heat exchanger of the present invention is made in accordance with the method comprising steps of (1) extruding a rectangular cross section tube which has a longitudinal through bore and opposite faces having parallel longitudinal grooves, (2) cutting parallel slots in the opposite faces, which slots are transverse to and extend into the longitudinal grooves to form a pattern of thin toothed fins between opposite unslotted groove face portions, (3) providing a cross bore in the tube ends which extend between the opposite face portions and is in fluid communication with the through bore, (4) placing two tubes in face-to-face abutment with the cross bores in axial alignment and the slots defining air flow passages through the abutting tubes, (5) sealing the abutting face portions around the periphery of the aligned cross bores, and (6) welding the abutting tubes together with welds entering the abutting grooved face portions.
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paten
Andrus Sceales, Starke & Sawall
Leo Leonard
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