Heat exchange – With repair or assembly means – Positioner or retainer for settable material
Reexamination Certificate
2001-05-02
2004-04-13
Flanigan, Allen (Department: 3743)
Heat exchange
With repair or assembly means
Positioner or retainer for settable material
C165S178000, C165S069000, C029S890043
Reexamination Certificate
active
06719037
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to heat exchangers and, more particularly, to heat exchangers utilizing tube-to-header joints.
2. Description of Related Art
Heat exchangers of many types, such as radiators, charge air coolers, oil coolers and the like, suffer limited life as a result of high working stresses at their tube-to-header joints. These stresses are a result of thermal expansion and contraction of the tubes, thermal changes in header length, and variations in internal pressure during operation. Since the tubes are usually rigidly attached to a relatively inflexible header by means of soldering, brazing, welding or the like, the resulting stresses ultimately lead to joint fatigue failure or tube fatigue in the area next to the joint.
In an effort to minimize or eliminate the stresses described above, some heat exchangers have been made with grommeted tube-to-header joints. In such heat exchangers, tube openings in the headers are made to be oversize with respect to the tubes. These openings are fitted with resilient grommets, usually made of high temperature silicone rubber. The grommets have slightly smaller openings than the tubes, so that when the tubes are pushed through the grommets the compression fit provides a leak-free connection of each tube to the header. The heat exchanger assembly involves the tedious handling of numerous small parts (the grommets), and lacks any real bond between the tubes and the headers, relying solely on the compression fit to provide a seal. To achieve the desired compression fit with the grommets, the fit and alignment of the core tubes to the grommeted header openings must be critically maintained through close dimensional tolerances. A major disadvantage of this design is that sealing is dependent on providing and maintaining a compression fit between the grommet, tube, and header.
Heat exchangers have also been made with specially made resilient headers. In such heat exchangers, a rigid metal header with oversized tube openings accepts loosely fitted brass ferrules in each tube opening. The brass ferrules are then bonded to the metal header by molding silicone rubber around each ferrule. The brass ferrules are later soldered to brass heat exchanger tubes.
The disadvantages of specially made resilient headers include the substantial amount of skill and labor required to solder the tubes and headers together. Further, great care must be exercised in the soldering operation to prevent destruction of the silicone bond to the ferrules. Also, the specially molded resilient headers are extremely expensive to produce.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a method of manufacturing a heat exchanger having long-life properties.
It is another object of the present invention to provide a method of manufacturing a heat exchanger with resilient headers or resilient tube-to-header joints.
It is a further object of the present invention to provide a method of manufacturing a heat exchanger having long-life properties and which is substantially simpler to manufacture.
It is another object of the present invention to provide a method of manufacturing a heat exchanger which requires fewer parts.
It is a further object of the present invention to provide a method of manufacturing a heat exchanger which requires less critical dimensional tolerances.
It is yet another object of the present invention to provide a method of manufacturing a heat exchanger which provides improved joint integrity.
It is still another object of the present invention to provide a method of manufacturing a heat exchanger which is easier to assemble.
It is another object of the present invention to provide a method of manufacturing a heat exchanger which provides a resilient tank to header joint.
It is a further object of the present invention to provide a heat exchanger which includes a resiliently bonded tube-to-header joint.
It is another object of the present invention to provide a heat exchanger which includes a sealing joint using compression and bonding.
It is another object of the present invention to provide a heat exchanger which includes a resilient joint including a bonded grommet.
It is another object of the present invention to provide a heat exchanger which includes a resilient tank to header joint.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
SUMMARY OF THE INVENTION
The above and other objects and advantages, which will be apparent to one of skill in the art, are achieved in the present invention which is directed to, in a first aspect, a method of making a heat exchanger by initially providing a header defining openings. The header openings are adapted to receive a plurality of tubes having outer surfaces. The tubes are inserted into the header openings such that the inner surfaces of the header openings and the outer surfaces of the tubes are adjacent to each other. Then, substantially uncured fluid sealing material is applied to at least the inner surfaces of the header openings such that the inner surfaces of the header openings and the outer surfaces of the tubes are connected by the sealing material. Finally, the method includes curing the sealing material after the tubes are inserted into the header openings, the sealing material provides a flexible, bonded, liquid tight, tube-to-header joint.
Preferably, the sealing material is an elastomer, and is cured by room temperature vulcanization or by ultraviolet light. The sealing material may be a liquid applied to the outer surface of the tubes. The inner surface of the header opening and the outer surface of the tubes frictionally fit in one preferred embodiment.
In another embodiment of the present invention a gap is defined by the inner surfaces of the header openings and the outer surfaces of the tubes, and the fluid sealing material is applied in the gap. In such case, the sealing material is essentially uncompressed after the curing.
The method may further include providing a tank having an inner cavity. The tank may be attached to or integral with the header such that the tubes extend through the header openings and open ends of the tubes communicate with the tank inner cavity.
Another aspect of the present invention relates to a method of making a heat exchanger by initially providing a header having openings. The header openings are adapted to receive a plurality of tubes. Then, the method includes providing a tank having an inner cavity. The tank is attached to the header. Next, the method includes inserting the tubes into the header openings and fixedly attaching the tubes to the header such that the tubes extend through the header openings and the open ends of the tubes communicate with the tank inner cavity. Then, the method includes applying substantially uncured fluid sealing material between the tank and the header defining a joint such that the header and the tank are connected by the sealing material. Finally, the method includes curing the sealing material of the joint such that the sealing material provides a flexible, bonded, liquid tight, header-tank joint. The tubes may be attached to the header by brazing.
A further aspect of the present invention provides a method of making a heat exchanger which initially provides a header defining openings having inner surfaces. The header openings are adapted to receive a plurality of tubes having outer surfaces. The method includes applying substantially uncured fluid sealing material to at least the inner surfaces of the header openings. Then, the method includes curing the sealing material, preferably by room temperature vulcanization or ultraviolet light, before the tubes are inserted into the header openings. The cured sealing material provides elastomeric members bonded to the inner surfaces of the header openings adapted to receive the tubes. Then, the tubes are inserted into the header openings such that the inner surfaces of
DeLio & Peterson LLC
Flanigan Allen
Peterson Peter W.
Transpro, Inc.
LandOfFree
Resiliently bonded 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 Resiliently bonded heat exchanger, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Resiliently bonded heat exchanger will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3199868