Information
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Patent Grant
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6520252
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Patent Number
6,520,252
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Date Filed
Friday, December 21, 200122 years ago
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Date Issued
Tuesday, February 18, 200321 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
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CPC
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US Classifications
Field of Search
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International Classifications
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Abstract
A heat exchanger assembly includes a plurality of fluid flow pathways including fins. Closure bars associated with each of the layers have a core reinforcing portion. Each core reinforcing portion includes first and second reinforcing members with a modified flow passage between them. The example embodiments include modified flow passages with generally C-shaped cross sections. The reinforcing portions preferably extend toward a center of the heat exchanger core varying distances along the body of the core so that reinforcing material is concentrated near the ends of the core where deformation caused by heat stress is most likely to occur.
Description
BACKGROUND OF THE INVENTION
This invention generally relates to plate-fin type heat exchangers. More particularly, this invention relates to a heat exchanger assembly having core-reinforcing closure bars.
Plate-fin type heat exchangers with various fluid flow patterns are well known. Typical arrangements include a core that comprises stacked layers of continuous corrugated fin elements. Each layer typically is mounted so that the channels formed by the fins in one layer are oriented relative to the channels formed by the fins in an adjacent layer so that fluid flow through the channels is in different directions. A parting sheet typically is placed between adjacent fin layers to maintain separation between alternate fluid flow paths. Top and bottom cover sheets typically are included at the ends of the heat exchanger core for structural support.
Conventional arrangements include closure bars mounted on the core sides that act as seals maintaining fluid flow in the desired direction through the channels.
One innovation in the design of closure bars is shown in U.S. Pat. No. 4,301,863, where extensions on the closure bars are provided to establish a spacing between the heat exchanger core and the locations where headers are welded to the closure bars. While such an arrangement has proven effective, those skilled in the art are always striving to make improvements.
One challenge facing designers of heat exchangers includes the competing interests between structural integrity and weight. Lightweight designs are particularly desirable for aircraft applications, for example. Utilizing less material or lighter weight materials, however, can be problematic if the structural integrity of the core is not sufficient to withstand the temperature extremes experienced by the heat exchanger. It has proven difficult to establish a heat exchanger design that withstands extreme temperatures, yet operates efficiently and does not weigh too much.
This invention addresses the need for an improved design by providing a heat exchanger assembly with closure bars that reinforce the core of the heat exchanger while minimizing the amount of additional weight compared to other designs. Additionally, the inventive arrangement strikes a balance between maximizing the efficiency of the heat exchanger while providing the desired enhanced structural integrity.
SUMMARY OF THE INVENTION
In general terms, this invention is a heat exchanger having core-reinforcing closure bars.
A heat exchanger assembly designed according to this invention includes a plurality of first fluid pathway layers that allow fluid to flow in a first direction through the assembly. A plurality of second fluid pathway layers allow fluid to flow in a second direction through the assembly. A parting sheet separates each of the fluid pathway layers. A plurality of first closure bars are associated with the first fluid pathway layers. The first closure bars have a solid surface that is operative to guide fluid through the first fluid pathways in the first direction. The closure bars have a reinforcing portion extending at least partially into the first fluid pathways. The reinforcing portion of each closure bar has first and second reinforcing members on opposite sides of a modified flow passage. The first and second reinforcing members are secured to corresponding ones of the parting sheets, respectively.
A second plurality of closure bars preferably is associated with the second fluid pathway layers. The second closure bars, like the first closure bars, preferably have a solid surface operative to guide fluid through the second fluid pathways in the second direction. A reinforcing portion of each second closure bar extends at least partially into the corresponding second fluid pathway. The reinforcing portions, in one example, have first and second reinforcing members on opposite sides of a modified flow passage. The first and second reinforcing members are secured to corresponding ones of the parting sheets, respectively.
In one example, the closure bars and fluid pathways are oriented so that the two different directions of fluid flow through the exchanger assembly are perpendicular relative to each other.
In one example, the reinforcing portions modified flow passages have a generally C-shaped cross section. The reinforcing portions preferably extend in toward a center of the core in a direction perpendicular to the fluid pathways varying distances along the length of the core of the heat exchanger assembly. The reinforcing portions preferably extend further into the core near ends of the heat exchanger where deformation is more likely. Near the central portion of the heat exchanger, the reinforcing portions preferably extend less toward the center of the core. Having varying dimensions of the reinforcing portions, facilitates enhancing the structural integrity of the assembly while minimizing the amount of material weight.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiments. The drawings that accompany the detailed description can be briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
illustrates a heat exchanger assembly designed according to this invention.
FIG. 2
illustrates, in somewhat more detail, selected features of the embodiment of FIG.
1
.
FIG. 3
schematically illustrates a closure bar designed according to this invention.
FIG. 4
illustrates another example closure bar designed according to this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As schematically shown in
FIG. 1
, a heat exchanger assembly
20
includes a plurality of first fluid pathway layers
21
that allow fluid flow in one direction through the assembly. The first layers
21
include a plurality of corrugated-style fins
22
as known in the art. A plurality of second fluid pathway layers
23
allow fluid flow through the assembly in a second direction, which in the illustrated example happens to be perpendicular to the first direction. The second layers
23
include fins
24
as known in the art.
A plurality of parting sheets
26
preferably separate the fluid pathway layers. Cover sheets
28
preferably are included on the ends of the assembly
20
. Only one cover sheet
28
is illustrated in FIG.
1
. The fins
22
,
24
, parting sheets
26
and cover sheets
28
preferably are assembled using a brazing method as known in the art.
A plurality of first closure bars
30
are associated with the first fluid pathway layers
21
that include the fins
22
. The first closure bars
30
include surfaces
32
that are adapted to be secured to the parting sheets
26
or a cover sheet
28
, depending on the position of the particular layer that a particular closure bar
30
is associated with. A second surface
34
on the closure bars
30
establishes a seal that is operative to guide fluid through the first fluid pathways
21
in the selected direction. The surfaces
34
preferably extend parallel to the desired direction of fluid flow along the fins
22
.
The closure bars
30
preferably include a header support section
36
including a welding surface
38
to which headers
39
can be secured using a conventional welding technique. The header supporting sections
36
preferably extend outward away from the body of the exchanger assembly core. Distancing the welding surfaces
38
from the fins
22
provides advantages when securing the headers
39
to the assembly
20
.
The closure bars
30
include a core reinforcing portion
40
. A first reinforcing member
42
is spaced from a second reinforcing member
44
. The reinforcing members
42
and
44
preferably extend inward into the body of the core of the heat exchanger assembly
20
. The reinforcing members
42
and
44
preferably are spaced apart from each other so that between them a modified fluid flow passage
46
is established to allow fluid flow in the first direction. In the illustrated example, the modified flow passage
46
has a generally C-shaped cross section. The reinforcing members
42
and
44
preferably are tapered relative to the surface
34
on the closure bars
30
so that the reinforcing members
42
and
44
have the greatest length adjacent the edge of the core of the assembly
20
at which fluid enters the flow pathway of the fins
22
.
A plurality of second closure bars
50
is associated with the fluid pathways
23
having the fins
24
. The closure bars
50
includes surfaces
52
that are adapted to be secured to the parting sheets in a conventional manner. Surfaces
54
provide a seal that operates to guide fluid flow along the fins
24
in the desired direction. In the illustrated example, the surfaces
54
on the closure bars
50
are perpendicularly oriented relative to the surfaces
34
on the closure bars
30
.
The closure bars
50
include a welding support portion
56
having a welding surface
58
to which the headers
39
can be welded in a conventional fashion. When the closure bars
50
and
30
are situated in the assembly
20
, the welding surfaces
38
and
58
preferably are aligned and adjacent to each other establishing a welding surface along the entire length (i.e., from top to bottom in
FIGS. 1 and 2
) of the assembly
20
.
The closure bars
50
include a core reinforcing portion
60
having reinforcing members
62
and
64
. A modified flow passage
66
preferably is established between the reinforcing member
62
and
64
. In the illustrated example, the modified flow passage
66
has a generally C-shaped cross section. Fluid flowing through the modified flow passage
66
preferably also encounters corresponding ones of the fins
24
as the fluid moves in the second direction through the second fluid pathways having fins
24
.
The reinforcing members
62
and
64
preferably extend toward a center of the core portion to provide reinforcing material at the corners of the core. The reinforcing member
62
and
64
preferably are tapered toward the surface
54
of the closure bars
50
as can be appreciated from
FIG. 4
, for example.
Including the reinforcing portions
40
and
60
on the closure bars provides greater stability and structural integrity to the heat exchanger core. The preferred arrangement includes a feature best appreciated from
FIG. 2
where the illustrated example includes reinforcing portions having varying lengths along the core. Reinforcing portions near the ends of the core preferably are longer than those associated with layers that are closer to the center of the core. The closure bars
30
, for example, preferably include reinforcing portions
40
that have a varying length along the core which follows a generally curved pattern illustrated in phantom at
80
. A corresponding curve pattern
82
preferably is followed by the reinforcing portion
60
of the closure bars
50
.
Utilizing shorter reinforcing portions at the layers that are near the center of the core compared to those associated with the layers near the ends of the core concentrates more material at locations where greater heat stress is likely to occur. Deformation of the core as caused by heat stress is more likely to occur near the ends (i.e., closer to the cover sheets
28
) than is likely to occur at the center of the core. Therefore, this invention includes concentrating more reinforcing material at the portions of the core that are more likely to experience deformation as a result of heat stress. A variety of patterns may be used, depending on the configuration and dimensions of a particular heat exchanger. In one example, there is approximately a one-quarter inch difference in length of the reinforcing members of each reinforcing portion compared to the next layer. In one example, the longest reinforcing portion is approximately one inch while the shortest is approximately one-eighth of an inch. Given this description, those skilled in the art will be able to select appropriate dimensions and configurations to meet the needs of their particular situation.
The closure bars
30
and
50
can be formed using conventional molding, casting or extrusion processes, for example. One example includes using Inconal 625 high nickel content steel as the preferred material for forming the closure bars. This material is believed to have structural properties that provides the necessary amount of strength while keeping the weight of the assembly within desired limits.
This invention provides a number of advantages, including providing a more structurally stable core arrangement that does not have significantly higher weight compared to previous arrangements. Another advantage associated with the inventive arrangement is that the parting sheet thickness may be changed. The thickness of the parting sheets can be varied between {fraction (45/1000)} and {fraction (5/1000)} of an inch. The reinforcing portions of the closure bars provide added structural stability that allows for thinner parting sheet thicknesses to be used, which provides weight advantages.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.
Claims
- 1. A heat exchanger assembly, comprising:a plurality of first fluid pathway layers that allow fluid to flow in a first direction through the assembly; a plurality of second fluid pathways layers that allow fluid to flow in a second direction through the assembly; a parting sheet separating each of the fluid pathway layers; and a plurality of first closure bars associated with the first fluid pathway layers, the first closure bars having a solid surface that is operative to guide fluid through the first fluid pathways in the first direction and having a reinforcing portion extending at least partially into the first fluid pathways, each reinforcing portion having a modified flow passage that allows fluid flow in the first direction, each reinforcing portion having two reinforcing members spaced apart from each other, a distal edge of the reinforcing members being spaced from the solid surface a varying distance along a length of the reinforcing members, a distance between the distal edges and the solid surface being greatest near one end of the reinforcing members.
- 2. The assembly of claim 1, including a plurality of second closure bars associated with the second fluid pathway layers, the second closure bars having a solid surface that is operative to guide fluid through the second fluid pathways in the second direction, the second closure bars having a reinforcing portion extending at least partially into the second fluid pathways, the reinforcing portions having a modified flow passage that allows fluid flow in the second direction.
- 3. The assembly of claim 2, wherein the first closure bars are perpendicularly oriented relative to the second closure bars.
- 4. The assembly of claim 2, wherein each second closure bar reinforcing portion has two reinforcing members spaced apart from each other, a distal edge of the reinforcing members being spaced from the solid surface a varying distance along a length of the reinforcing members, a distance between the distal edges and the solid surface being greatest near one end of the reinforcing members.
- 5. The assembly of claim 4, including a header attachment surface on each second closure bar and a concave transition between the header attachment surface and a portion of the reinforcing members that is aligned to face in the same general direction as the header attachment surface.
- 6. The assembly of claim 4, wherein the modified flow path has a varying depth along the length of the path.
- 7. The assembly of claim 1, wherein the reinforcing portions modified flow passages each have a generally C-shaped cross section.
- 8. The assembly of claim 1, wherein the reinforcing portions in one layer extend in a distance different than that of a next layer.
- 9. The assembly of claim 8, wherein the distance extending into the assembly is largest near ends of the assembly and the distance becomes increasingly smaller for the layers approaching a central layer of the assembly.
- 10. The assembly of claim 1, wherein the assembly includes headers and the closure bars have header supporting portions extending away from the pathway layers.
- 11. The assembly of claim 10, wherein the reinforcing portions are open at one end distal from the header supporting portions.
- 12. The assembly of claim 1, including fins in the pathways arranged relative to the closure bars such that fluid passing through the modified passages of the reinforcing portions passes over corresponding portions of the fins.
- 13. The assembly of claim 1, wherein the reinforcing portions each include reinforcing members on opposite sides of the modified flow passage.
- 14. The assembly of claim 1, including a header attachment surface near one end of the closure bar with a concave transition between the header attachment surface and the solid surface.
- 15. The assembly of claim 1, wherein the distal edges of the reinforcing members taper toward the solid surface in a direction into the assembly.
- 16. A closure bar for use in a heat exchanger, comprising:a body having a first surface adapted to establish a seal and to direct fluid flow generally parallel to the first surface and a core reinforcing portion having first and second reinforcing members extending away from the first surface and spaced apart such that a flow passage exists between the reinforcing members, the reinforcing members having an edge distal from the first surface, the distal edge of the reinforcing members being spaced from the first surface a varying distance along a length of the reinforcing members, the distal edges being a greatest distance from the first surface near one end of the reinforcing members.
- 17. The closure bar of claim 16, including a header attachment surface near one end of the closure bar with a concave transition between the header attachment surface and the first surface.
- 18. The closure bar of claim 16, including a header attachment surface and a concave transition between the header attachment surface and a portion of the reinforcing members that is aligned to face in the same general direction as the header attachment surface.
- 19. The closure bar of claim 16, wherein the modified flow path has a varying depth along the length of the path.
US Referenced Citations (6)