Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Patent
1996-03-05
1997-11-11
Cuda, Irene
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
29890043, F28F 904
Patent
active
056850751
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND ART
This invention relates to a method for brazing flat tubes of a laminated heat exchanger in which tube insertion ports of header tanks and flat tubes to be inserted into the tube insertion ports have an improved brazing property.
A conventionally used laminated heat exchanger has flat tubes laminated and connected to header tanks, and a heat-exchanging medium meandered a plurality of times to flow between inlet and outlet joints disposed on the header tanks.
For such flat tubes of a laminated heat exchanger, various types are known; e.g., (1) made by overlaying two plates having many projections (hereinafter referred to as beads) which are protruded inward to have their ends connected to one another, and brazing joints at both ends of the plates; (2) made by forming many projections (beads) on one plate which has a certain area, folding the plate double at the center, and brazing joints to connect mutually; (3) made by inserting inner fins inside; and (4) made by extrusion molding.
The flat tubes of the above (1) and (2) have a structure that beads cause a heat-exchanging medium to make a turbulent flow within the flat tubes to enhance a heat-exchanging capacity, increase the strength of the tube's flat surfaces, and improve a pressure resistance.
In general the header tanks have tube insertion ports corresponding to the cross sections of the above various flat tubes formed in multiple numbers by pressing or the like, these tube insertion ports being formed to have an external size slightly larger than the cross section of the flat tubes so that the laminated multiple flat tubes can be inserted by a single action, and after insertion, the flat tubes and the tube insertion ports being fitted completely.
And, to assemble a heat exchanger, a jig is used to laminate the multiple flat tubes with fins between respective flat tubes, the both ends of each flat tube are inserted into the tube insertion ports formed in the header tanks, and the both ends of each flat tube are brazed with the tube insertion ports of the header tanks in a furnace (e.g., Japanese Patent Application Laid-open Print No. Hei 4-62394).
But, when a clearance between the tube insertion ports and the flat tubes to be inserted therein is excessive, the flat tubes can be inserted easily, but there is a disadvantage that the flat tubes and the header tanks are not brazed completely.
When the clearance between the tube insertion ports and the flat tubes is too small, the flat tubes are hard to be inserted, making it impossible to assemble, and if they are forcedly assembled, the flat tubes may be crushed, or even if they can be assembled, there is a disadvantage that a lot of steps are required to adjust the assembling.
In particular, the flat tubes which are of the type having two plates of brazing sheet overlaid or of the type having one plate folded are required to be assembled carefully because they become thin.
Besides, with the above flat tubes which are of the type having two plates overlaid or of the type having one plate folded, when the clearance between the tube insertion ports and the flat tubes is made small, the thermal expansion in the breadth direction of the flat tubes upon brazing is limited by the both ends in the width direction of the tube insertion ports of the header tanks, the flat tubes are deformed and expanded in the thickness direction, and respective beads of the flat tubes disposed near the tube insertion ports cannot be contacted mutually, thereby causing a disadvantage that the opposed beads cannot be brazed. As a result, the flat tubes can not acquire a sufficient pressure resistance. For example, flat tubes for a condenser are not satisfactory in terms of a pressure resistance.
In view of the above, this invention aims to provide a method for brazing flat tubes for a laminated heat exchanger in which a brazing property of the tube insertion ports and the flat tubes can be improved while keeping an insertion property of the flat tubes when assembling, and even for the flat tubes which are of the typ
REFERENCES:
patent: 3855682 (1974-12-01), Chartet
patent: 4377024 (1983-03-01), Saperstein
patent: 5251374 (1993-10-01), Halstead et al.
patent: 5271151 (1993-12-01), Wallis
patent: 5292056 (1994-03-01), Borchert et al.
patent: 5423112 (1995-06-01), Murphy et al.
Cuda Irene
Zexel Corporation
LandOfFree
Method for brazing flat tubes of laminated heat exchanger does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for brazing flat tubes of laminated heat exchanger, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for brazing flat tubes of laminated heat exchanger will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1219987