Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Reexamination Certificate
1999-08-25
2001-06-26
Cuda Rosenbaum, I (Department: 3726)
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
C029S890043, C029S890054
Reexamination Certificate
active
06249968
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to heat exchange structures, and is particularly concerned with improvements in heat exchangers of the type disclosed in U.S. Pat. No. 5,501,270 issued Mar. 26, 1996 in the names of the present inventor and Barry W. Blumel.
2. Background Information
U.S. Pat. No. 5,501,270 shows a heat exchange structure that comprises a stack of metal fins laced together by parallel tubes. Consecutive fins are substantially uniformly spaced from each other throughout the stack. The fins comprise identical patterns of collared holes through which the tubes lace the stack. The tubes have oval transverse cross sections. In plan view, the fin holes have oval shapes just slightly larger than the oval cross sections of the tubes. The fins and tubes are brazed together around each hole through which a tube passes.
When the heat exchanger is in use, a first heat exchange fluid flows through the parallel tubes, and a second heat exchange fluid flows through the stack from a front face of the stack to a rear face of the stack. The second heat exchange fluid enters the front face from a direction that is generally perpendicular to the tubes.
Within the interior of the stack, a major portion of the area of each fin lies in a respective plane that is non-perpendicular to the direction from which the second fluid approaches it. In general, those interior portions of the fins are disposed in planes that are non-perpendicular to the direction from which the second fluid approaches the front face of the stack.
In addition to the collared holes, the interior portions of the fins contain rows of louvered slots arranged to cause the second fluid to flow through the slots as it passes through the stack. The novel core constructions disclosed in the referenced patent are efficient in respect of both heat exchange and fluid pressure drop.
SUMMARY OF THE INVENTION
In a general respect, the present invention relates to improvements in fabricating heat exchanger cores, especially cores that comprise tubes having generally flat, oblong cross sections, for facilitating the lacing of tubes through fins stacks and for mechanically staking the tubes to the fins prior to metallurgical bonding of the tubes to the fins.
A general aspect of the within claimed invention relates to a method of making a heat exchanger core that comprises a stack of fins having sets of aligned holes through which tubes are laced, the method comprising: corrugating at least portions of the lengths of the tubes; lacing each tube through a respective set of aligned holes in the fins; and then expanding the cross sections of the corrugated portions of the tubes.
Another general aspect of the within claimed invention relates to a method of making a heat exchanger core that comprises a stack of fins having sets of aligned oval holes through which tubes of oval cross section are laced, wherein the oval cross section of the tube comprises nominal width and thickness having substantially flat, substantially parallel, sides that are spaced apart in the direction of the nominal thickness and that are joined by rounded ends in the direction of nominal width, the method comprising: corrugating the substantially flat, substantially parallel, sides of the tubes along at least portions of the lengths of the tubes and lacing each tube through a respective set of aligned holes in the fins; and then expanding the cross sections of the tubes containing the corrugated sides.
Still another general aspect of the within claimed invention relates to a method of making a heat exchanger core that comprises a stack of fins having at least one set of aligned holes through which a respective nominally oval tube is laced, the method comprising: for each set of aligned holes, providing a respective tube that has an oval cross section of nominal width and thickness and a corrugated lengthwise leading end portion that has a transverse cross section of overall width and thickness slightly less than the nominal width and thickness of the oval cross section; and lacing each tube through the respective set of holes by inserting the leading lengthwise end portion into a first hole of the respective set that is in a first of the fins in the stack and then through successive holes of the respective set that are in successive fins in the stack.
Still another general aspect of the within claimed invention relates to a method of making a heat exchanger core that comprises a stack of fins having at least one set of aligned holes through which a respective nominally oval tube is laced, the method comprising: for each set of aligned holes, providing a respective tube that comprises an oval cross section of nominal width and thickness having substantially flat, substantially parallel, sides that are spaced apart in the direction of the nominal thickness and that are joined by rounded ends in the direction of nominal width and that comprises a lengthwise leading end portion that comprises a transverse cross section of overall width and thickness slightly less than the nominal width and thickness of the oval cross section and that comprises corrugated sides continuing lengthwise of the tube from the substantially flat, substantially parallel, sides of the oval cross section of nominal width and thickness; and lacing each tube through the respective set of holes by inserting the corrugated leading lengthwise end portion into a first hole of the respective set that is in a first of the fins in the stack and then through successive holes of the respective set that are in successive fins in the stack.
The invention also relates to heat exchanger cores made by these methods.
Other general and more specific aspects will been set forth in the ensuing description and claims.
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Cuda Rosenbaum I
Shelton Larry I.
Visteon Global Technologies Inc.
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