U.S. patent application number 13/743986 was filed with the patent office on 2014-07-17 for plate heat exchanger.
This patent application is currently assigned to HAMILTON SUNDSTRAND CORPORATION. The applicant listed for this patent is HAMILTON SUNDSTRAND CORPORATION. Invention is credited to Michael R. Barone, Matthew William Miller, Richard Rusich.
Application Number | 20140196870 13/743986 |
Document ID | / |
Family ID | 49920277 |
Filed Date | 2014-07-17 |
United States Patent
Application |
20140196870 |
Kind Code |
A1 |
Rusich; Richard ; et
al. |
July 17, 2014 |
PLATE HEAT EXCHANGER
Abstract
A plate heat exchanger includes a plurality of main plates
having ridges and troughs to direct first and second flows of
fluids across the main plates to exchange heat between the fluids
while maintaining the first and second flows of fluids separate
from each other. The heat exchanger also includes a first end plate
including first and second inlets and first and second outlets. The
first end plate includes a substantially flat inside surface
configured to contact the ridges of a first main plate among the
plurality of main plates and at least one slot formed in the
substantially flat surface to provide a fluid communication of the
first fluid flow between the inlet and a cavity formed by the first
end plate and the first main plate.
Inventors: |
Rusich; Richard; (Ellington,
CT) ; Barone; Michael R.; (Amston, CT) ;
Miller; Matthew William; (Enfield, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HAMILTON SUNDSTRAND CORPORATION |
Windsor Locks |
CT |
US |
|
|
Assignee: |
HAMILTON SUNDSTRAND
CORPORATION
Windsor Locks
CT
|
Family ID: |
49920277 |
Appl. No.: |
13/743986 |
Filed: |
January 17, 2013 |
Current U.S.
Class: |
165/104.14 |
Current CPC
Class: |
F28F 3/005 20130101;
F28F 3/083 20130101; F28D 9/005 20130101; F28F 2265/16
20130101 |
Class at
Publication: |
165/104.14 |
International
Class: |
F28F 3/00 20060101
F28F003/00 |
Claims
1. A plate heat exchanger, comprising: a plurality of main plates
having ridges and troughs to direct first and second flows of
fluids across the main plates to exchange heat between the fluids
while maintaining the first and second flows of fluids separate
from each other; and a first end plate including first and second
inlets to provide the first and second flows to the plurality of
main plates and first and second outlets to output the first and
second flows from the plurality of main plates, the first end plate
including a substantially flat inside surface configured to contact
the ridges of a first main plate among the plurality of main plates
and at least one slot formed in the substantially flat surface to
provide a fluid communication of the first fluid flow between the
inlet and a cavity formed by the first end plate and the first main
plate.
2. The plate heat exchanger of claim 1, wherein the at least one
slot includes a first slot extending radially from the first inlet,
a second slot having a substantially circumferential shape around a
portion of the first inlet and connected to the first slot, and a
third slot extending lengthwise along a center of the first end
plate.
3. The plate heat exchanger of claim 1, wherein the at least one
slot includes a first slot extending circumferentially around an
entire circumference of the first inlet, and a second slot
extending lengthwise along a center of the first end plate.
4. The plate heat exchanger of claim 1, wherein the first fluid is
pressurized in the cavity formed by the first end plate and the
first main plate.
5. The plate heat exchanger of claim 1, wherein the first main
plate includes a plurality of ridges separated by a plurality of
troughs, the plurality of troughs and ridges forming a chevron
pattern, the at least one slot includes a first slot adjacent to
the first inlet and a second slot extending lengthwise along a
center of the first end plate at an apex of the chevron pattern,
and the first slot is in fluid communication with at least one
trough between adjacent ridges of the first main plate, the at
least one trough is in fluid communication with the second slot,
and the second slot is in fluid communication with each other
trough of the plurality of troughs.
6. The plate heat exchanger of claim 1, further comprising a
protrusion surrounding the first inlet on an inside surface of the
first end plate, the protrusion configured to contact the first
main plate to form a fluid-tight seal with the first main
plate.
7. The plate heat exchanger of claim 1, wherein the first main
plain includes a ridged portion and a flange surrounding the ridged
portion and extending outward from the ridged portion to have a
draft angle that is an acute angle, and the first end plate
comprises a body having an inside surface configured to contact the
ridges of the ridged portion of the first main plate and a flange
surrounding the main body, an inside surface of the flange of the
first end plate configured to contact an outer surface of the
flange of the first main plate, and a draft angle of the first end
plate being less than the draft angle of the first main plate
8. The plate heat exchanger of claim 7, further comprising: a
second main plate among the plurality of plates, the second main
plate including a ridged portion and a flange surrounding the
ridged portion and extending outward from the ridged portion to
have a draft angle that is an acute angle; and a second end plate
having a first outer side configured to contact the ridged portion
of the second main plate and a second outer side surrounding the
first outer side and having a draft angle that is an acute angle,
the second outer side configured to contact an inner side of the
flange of the second main plate, the draft angle of the second
outer side being greater than the draft angle of the second main
plate.
9. The plate heat exchanger of claim 1, wherein the first end plate
includes at least one thin region and at least one thick region,
the at least one thick region located in a region identified as
being subject to a greater stress than the at least one thin region
when the plate heat exchanger is in operation.
10. The plate heat exchanger of claim 9, wherein the at least one
thick region includes regions surrounding the first and second
inlets and first and second outlets at ends of the first end plate,
and ribs extending width-wise across the first end plate.
11. The plate heat exchanger of claim 1, wherein the first end
plate includes at least one receptacle on an outward-facing surface
opposite the inside surface, the at least one receptacle comprising
a base and a protrusion having a shape configured to receive and
surround a mounting stud, such that sides of the mounting stud
contact sides of the protrusion while an end of the mounting stud
contacts the base of the receptacle.
12. The plate heat exchanger of claim 1, further comprising a fluid
fitting configured to fit into at least one of the first inlet and
the first outlet to provide a flow of fluid through the fluid
fitting into or out from the plurality of main plates, the fluid
fitting including a recess in a surface adjacent to an inner
diameter surface of the at least one of the first inlet and the
first outlet.
13. The plate heat exchanger of claim 12, wherein the recess
surrounds the fitting.
14. The plate heat exchanger of claim 12, wherein the inside
diameter surface of the first inlet or the second inlet includes a
pilot located linearly between the recess and an end of the inside
diameter surface corresponding to the inside surface of the first
end plate and a braze region located between the recess and an end
of the inside diameter surface corresponding to an outer surface of
the first end plate, the braze region having a diameter greater
than the pilot.
15. The plate heat exchanger of claim 1, further comprising: a
second end plate on an opposite side of the plurality of main
plates from the first end plate.
16. The plate heat exchanger of claim 15, wherein the second end
plate includes a substantially flat inside surface configured to
contact the ridges of a second main plate among the plurality of
main plates and at least one slot formed in the substantially flat
surface to fill with fluid from one of the first fluid flow and the
second fluid flow a cavity formed by the second end plate and the
second main plate.
17. The plate heat exchanger of claim 15, wherein each of the first
end plate and the plurality of main plates includes a flange
surrounding a ridged portion, the flanges of the first end plate
and the plurality of main plates extending toward the second end
plate and being in contact with a flange of an adjacent main plate
to inhibit movement of the first end plate and the plurality of
main plates, and the second end plate includes an upper surface and
an outer side surface surrounding the upper surface and having a
draft angle that is an acute angle, the second side surface
configured to contact a flange of a second main plate among the
plurality of main plates and the draft angle of the second side
surface being greater than a draft angle of the flange of the
second main plate.
18. The plate heat exchanger of claim 17, wherein the outer side
surface of the second end plate has a draft angle greater than a
draft angle of the flange of the first end plate.
19. A plate heat exchanger, comprising: a plurality of main plates
having a ridged region including ridges and troughs to direct first
and second flows of fluids across the main plates to exchange heat
between the fluids while maintaining the first and second flows of
fluids separate from each other, each of the plurality of main
plates further including a flange extending from the ridged region
at an oblique angle; and a first end plate including first and
second inlets to provide the first and second flows to the
plurality of main plates and first and second outlets to output the
first and second flows from the plurality of main plates, the first
end plate including a substantially flat main surface configured to
contact the ridged region of a first main plate among the plurality
of main plates and a flange surrounding the main surface and
extending at an oblique angle with respect to the main surface, the
flange of the first end plate having a draft angle less than a
draft angle of the flange of the first main plate.
Description
BACKGROUND OF THE INVENTION
[0001] Embodiments of the invention relate to a plate heat
exchanger, and in particular to end plates of plate heat
exchanger.
[0002] Plate heat exchangers are widely used in the commercial
industry as a means of exchanging energy between two liquids. The
construction consists of a series of main plates having ribbed
patterns on their surfaces and stacked one on top of the other.
This arrangement forms channels between the plates through which
the two liquids pass. As the two liquids enter their respective
inlet ports they are independently directed to flow into
alternating fin channels which permits heat to transfer from one
liquid to the other. In order to maintain separation of the two
liquids within the ports, the main plates incorporate local
depressions in the port areas which alternately block off the flow
passage from the port to the fin channels. In this way each port is
hydraulically connected to every other fin channel. Each plate is
coated with a braze filler metal. The entire heat exchanger
assembly is placed in a furnace where the filler metal is melted
creating a metallurgical bonds between the plates and forming a
fluid seal.
[0003] Plate heat exchangers include top and bottom seal plates and
top and bottom outer plates on outward-facing surfaces of the top
and bottom seal plates, respectively. The top seal plate has a
smooth surface and the bottom seal plate has a ribbed inward-facing
surface (toward a center of the plate heat exchanger) and a smooth
outward-facing surface (away from the center of the plate heat
exchanger). The top and bottom seal plates form the outer pressure
vessel of the heat exchanger. Typically, individual seals or seal
slugs must be installed to block off the flow passage from an inlet
port to a flow channel in the plate heat exchanger. The seal slugs
are positioned around the inlets between the top seal plate and an
adjacent main plate. However, the position of the individual seal
slugs can shift during assembly and therefore are prone to cause
fluid leakage of the heat exchanger.
[0004] In addition, ambient air can migrate into the space between
the top seal plate and top outer plate. While the fluids passing
through the heat exchanger may exhibit low freezing points that
allow their temperatures to fall below 0.degree. F. (-17.78.degree.
C.) without affecting the liquid states of the fluids, moisture
within the ambient air freezes at 32.degree. F.(0.degree. C.).
Consequently, the moisture in trapped between the top seal plate
and the top outer plate may expand and crack the heat exchanger
plates resulting in fluid leakage.
[0005] In addition, the draft angle of flanges of the main plates
are chosen to ensure a proper braze seal between each main plate.
The raised ribbed areas (herringbones) control the distance of
separation between adjacent plates. A top seal plate having a
flange with a same draft angle as an adjacent main plate may result
in a poor fit, since the top seal plate does not include ridges.
The poor fit may result in poor braze adhesion and fluid
leakage.
[0006] The heat exchanger is subjected to stresses from the
internal fluid pressures. The top plate and bottom plate provided
support and stiffness to resist the internal pressure. The load
emanating from the fluid pressure in the vicinity of the ports is
commonly called a plug load. The area immediately surrounding the
port areas is inherently subjected to high stresses due to the
reduction of material (port holes) which must exist to allow fluid
flow. Insufficient material around the port holes results in the
inability of the heat exchanger to withstand low cycle fatigue
resulting from pressure cycles of the liquids, ultimately leading
to cracks and fluid leakage. However, the addition of excess
material to compensate for the local high stresses would result in
large weight penalties which cannot be tolerated in some
applications, such as aerospace applications.
[0007] In addition, a position tolerance of the ports is subject to
the ability to maintain a repeatable and consistent stack height of
the main plates. Small variations in material thickness of the main
plates (in the order of thousandths of an inch) will multiply by
the number of main plates. An eighty-plate heat exchanger, for
example can differ in stack height from unit to unit by 20
millimeters (mm) if each main plate had a variation of just 0.25
mm. When considering the additional position tolerances associated
with other components of the heat exchanger, the resultant position
tolerance of the ports can be 2.5 mm for example. This large
variation from unit to unit is unacceptable for installations where
precision is critical.
[0008] Mounting studs are conventionally welded to the thin top
plate and bottom plate prior to furnace braze of the heat exchanger
assembly. This requires time consuming welding and flush grinding
of the underlying surfaces of the top and bottom plates adjacent to
the studs to ensure a smooth uninterrupted surface against the
adjacent main plates. The resultant strength of the stud retention
is dramatically reduced. Also, the relatively thin top and bottom
plates prevent sufficient thread engagement yielding a large
variation in position tolerance of the studs. Additionally, the
fluid fittings are historically welded to the weld stubs after
furnace brazing. This requires time consuming welding and greater
position tolerance of the final location of the fittings. The large
variation from unit to unit is unacceptable for installations where
precision is critical.
BRIEF DESCRIPTION OF THE INVENTION
[0009] Embodiments of the present invention include a plate heat
exchanger that includes a plurality of main plates having ridges
and troughs to direct first and second flows of fluids across the
main plates to exchange heat between the fluids while maintaining
the first and second flows of fluids separate from each other. The
heat exchanger also includes a first end plate including first and
second inlets to provide the first and second flows to the
plurality of main plates and first and second outlets to output the
first and second flows from the plurality of main plates. The first
end plate includes a substantially flat inside surface configured
to contact the ridges of a first main plate among the plurality of
main plates and at least one slot formed in the substantially flat
surface to provide a fluid communication of the first fluid flow
between the inlet and a cavity formed by the first end plate and
the first main plate.
[0010] Embodiments of the invention further include a plate heat
exchanger including a plurality of main plates having a ridged
region including ridges and troughs to direct first and second
flows of fluids across the main plates to exchange heat between the
fluids while maintaining the first and second flows of fluids
separate from each other. Each of the plurality of main plates
further includes a flange extending from the ridged region at an
oblique angle. The plate heat exchanger further includes a first
end plate including first and second inlets to provide the first
and second flows to the plurality of main plates and first and
second outlets to output the first and second flows from the
plurality of main plates. The first end plate includes a
substantially flat main surface configured to contact the ridged
region of a first main plate among the plurality of main plates and
a flange surrounding the main surface and extending at an oblique
angle with respect to the main surface. The flange of the first end
plate has a draft angle less than a draft angle of the flange of
the first main plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0012] FIG. 1 is an exploded view of a plate heat exchanger
according to one embodiment;
[0013] FIG. 2A is a perspective view of a bottom end plate
according to an embodiment;
[0014] FIG. 2B is a cut-away view of a portion of a bottom end
plate according to an embodiment;
[0015] FIG. 3A is a top view of a top end plate according to one
embodiment;
[0016] FIG. 3B is a cut-away view of the top end plate according to
an embodiment;
[0017] FIG. 3C is a top view of a top end plate according to
another embodiment;
[0018] FIG. 3D is a cut-away view of the top end plate according to
an embodiment;
[0019] FIG. 3E is a cut-away view of the top end plate and a main
plate according to an embodiment;
[0020] FIG. 4A illustrates a flange of a top end plate according to
one embodiment;
[0021] FIG. 4B illustrates the flange of the top end plate in
contact with a main plate according to one embodiment;
[0022] FIG. 4C illustrates a bottom end plate in contact with a
main plate according to one embodiment;
[0023] FIG. 5A illustrates a perspective view of an outward-facing
side of a top end plate according to one embodiment;
[0024] FIG. 5B illustrates a perspective view of an outward-facing
side of a bottom end plate according to one embodiment;
[0025] FIG. 6 illustrates the mounting of a stud according to a
conventional configuration;
[0026] FIG. 7 illustrates a stud-mounting portion of an end plate
according to one embodiment of the invention; and
[0027] FIG. 8 illustrates a cut-away view of a portion of a top end
plate and a fluid fitting according to one embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0028] Conventional plate heat exchangers have structures that
result in cracking in leaking due to misalignments of parts of the
plate heat exchangers. Embodiments of the invention relate to a
plate heat exchanger having end plates configured to improve the
structural integrity of the plate heat exchanger, reducing cracking
and leaks.
[0029] FIG. 1 is an exploded view of a plate heat exchanger 100
according to one embodiment. The plate heat exchanger 100 includes
main plates 110 having ridged regions 111 and openings 112
corresponding to inlets and outlets of a fluid. The ridged regions
111 may have a herringbone or chevron pattern to increase a surface
area of the main plate 110 contacted by the fluid and to generate
turbulence in the fluid. The openings 112 of the main plates may be
provided, alternatingly, with protrusions or recesses surrounding
the openings 112 to alternate a fluid that enters a cavity between
the main plates. For example, a first fluid may enter first, third
and fifth cavities between the main plates, and a second fluid may
enter second, fourth and sixth cavities. The fluids are maintained
separate and exchange heat as they flow through the cavities.
[0030] The plate heat exchanger 100 includes a first end plate 120,
also referred to herein as a top end plate 120 for purposes of
description. The plate heat exchanger 100 also includes a second
end plate 130, also referred to herein as a bottom end plate 130
for purposes of description. The top end plate 120 and bottom end
plate 130 are positioned at opposite sides of the plurality of main
plates 110. It is understood that although the terms "top" and
"bottom" may be used for purposes of description, embodiments of
the invention encompass a plate heat exchanger 110 having the first
and second end plates 120 and 130 arranged with any spatial
alignment relative to an earth plane.
[0031] The illustrated top end plate 120 includes openings 122 to
receive fluid fittings 151, 152, 153 and 154. A first fluid may be
input to the plate heat exchanger 100 via a fluid fitting 150 and
output from the heat exchanger via a fluid fitting 152. Another
fluid may be input to the plate heat exchanger 100 via the fluid
fitting 153 and output from the plate heat exchanger 100 via the
fluid fitting 154. Weld stubs 155, 156, 157 and 158 may also be
provided between a wide portion of the fluid fittings 151, 152, 153
and 154 and the top end plate 120.
[0032] While particular shapes are used in FIG. 1 to represent the
main plates 110, end plates 120 and 230, fittings 151, 152, 153 and
154, it is understood that these and other elements may have any
desired shape. For example, the main plates 110 may have
substantially rectangular, square, oval or any polygonal shape. In
addition, the openings 112 and 122 may have a round shape, oval
shape, square shape, or any other desired shape. Embodiments of the
invention are not limited to the shapes illustrated, but include
plate heat exchangers having any desired shape.
[0033] FIGS. 2A and 2B illustrate an integrated seal feature of a
bottom end plate 230 according to one embodiment. The bottom end
plate 230 may correspond to the bottom end plate 130 of FIG. 1. The
bottom end plate 230 includes an inward-facing surface 231, inlet
regions 232a and 232b and outlet regions 232c and 232d. The inlet
region 232b and the outlet region 232d each include a raised
portion 233, which may also be referred to as a protrusion 233,
surrounding an area corresponding to an opening in an adjacent main
plate to prevent a first flow fluid from flowing across the surface
230 from the inlet region 232b and from flowing out from the
surface 230 via the outlet region 232d. In contrast, the inlet
region 232a and outlet region 232c include no such raised portion
233 or protrusion. Consequently, fluid from the inlet region 232a
flows over the inward-facing surface 231 and out through an opening
in an adjacent main plate at the outlet region 232c.
[0034] While the raised portions 233 of the bottom end plate 230
are illustrated in FIGS. 2A and 2B, the top end plate includes
similar raised portions. However, where the bottom plate 230 is
closed-off or solid in each of the inlet regions 232a and 232b and
outlet regions 232c and 232d, the inlet regions and outlet regions
of the top plate are open to permit the flow of fluid through the
top plate, such as by inserting fluid fittings or ports into the
top plate. Accordingly, the raised portions on an inward-facing
surface surrounding one inlet and one outlet of the top plate
prevent fluid from flowing in a cavity between the top plate and an
adjacent main plate. Conversely, the absence of the raised portions
around another of the inlets and outlets permits fluid flow into
and out from the cavity between the top plate and an adjacent main
plate.
[0035] FIGS. 3A to 3E illustrate a top end plate 320 including
flow-permitting slots according to one embodiment. The top end
plate 320 may correspond to the top end plate 120 of FIG. 1. In
FIGS. 3A and 3C, a view of the figures is of a top side 329 or
outward-facing side 329 of the top end plate 320. Dashed lines
represent features on an underside 330 of the top end plate 320
relative to the viewpoint of the figure (or in other words,
features located on an inward-facing side 330). Dashed and dotted
lines represent features on a main plate 370 (of FIG. 3E, for
example) adjacent to the inward-facing side which are illustrated
for purposes of description.
[0036] The top end plate 320 includes openings 322a, 322b, 322c and
322d corresponding to fluid inlets and outlets. For purposes of
description, opening 322c will be described as a fluid inlet 322c
and opening 322d will be described as a fluid outlet 322d.
Depressions or slots 323, 324, 325 and 326 are formed in the
inward-facing surface 330 of the top end plate 320. Slots 323 and
325 connect to, and extend radially from the inlet 322c and the
outlet 322d, respectively. Slots 324 and 326 may be connected to
the slots 323 and 325, and may partially surround the inlet 322c
and the outlet 322d, respectively, along an outer edge of the
inward-facing surface 330 of the top end plate 320.
[0037] A slot 327 may extend lengthwise along a center of the top
end plate 320. In another embodiment, the slot 327 may be
off-center. In FIG. 3, the location of the slot 327 is positioned
to correspond to an apex of the herringbones or chevrons 311 of an
adjacent main plate 370 (in FIG. 3E, for example). While only a few
ridges 311 are illustrated in FIGS. 3A and 3C for purposes of
description, it is understood that ridges 311 of the adjacent main
plate extend over an entire surface of the adjacent main plate.
When fluid F is input to the opening 322c from an external source
and input to the opening 322d from a channel within the plate heat
exchanger, fluid F from the openings 322c and 322d enters the slots
323 and 325, and from the slots 323 and 325, the fluid is
transmitted to the slots 324 and 326. The slots 324 and 326 are in
fluid communication with troughs located between the ridges 311 of
the adjacent main plate. Accordingly, fluid F from the slots 324
and 326 flows through the troughs between the ridges 311 to the
slot 327. From the slot 327, the fluid F may flow into any trough
between ridges 311 of the main plate. Consequently, the fluid F may
fill every cavity between the top end plate 320 and the adjacent
main plate.
[0038] Referring to FIGS. 3B, 3D and 3E, in embodiments of the
invention, the space between the top end plate 320 and the adjacent
main plate is hermetically sealed, such as via a braze joint, from
the ambient environment. This may be accomplished in one embodiment
by incorporating a flange 334 to the top end plate 320 with the
proper draft angle to ensure that the faying surface 335 between
the top end plate flange 334 and the adjacent main plate flange 336
is brazed and entirely sealed from the ambient environment. This
may reduce ambient moisture from entering this space and
subsequently freeze and rupture the plates.
[0039] To ensure that the faying surfaces 335 have been properly
brazed, the space between the plates, which may also be referred to
as a dead zone 371, is pressurized with one of the fluids F
entering the heat exchanger. Any voids in the braze will be
immediately detected as an external leak during final test of the
heat exchanger. A hermetically sealed joint may be detected by
detecting no evidence of leakage. To achieve the pressurized dead
zone 371, the port area, or the openings 322c and 322d and the dead
zone may be hydraulically connected. The slots 323, 324, 325, 326
and 327 are strategically located to allow fluid pressure to enter
each and every herringbone space between the top end plate 320 and
the adjacent main plate 370. While only the top end plate 320 is
illustrated in FIGS. 3A to 3E, similar slots may be formed in the
bottom end plate, such as the bottom end plate 130 of FIG. 1, to
similarly pressurize the dead zone 371 between the bottom end plate
and an adjacent main plate.
[0040] A raised portion 328 or protrusion 328 surrounds the opening
322a to prevent fluid from the opening 322a from entering the dead
zone 371 between the top end plate 320 and an adjacent main plate
370. The raised portion 328 is illustrated with dashed lines in
FIGS. 3A and 3C.
[0041] While FIGS. 3A and 3B illustrate slots 323, 324, 325 and
326, any configuration of slots may be used that allow for the
fluid F from at least one of the openings 322a, 322b, 322c and 322d
to fill the dead zone between the top end plate 320 and an adjacent
main plate 370. For example, FIGS. 3C and 3D illustrate an
embodiment in which a slot 332 or depression 332 is formed to
entirely or substantially surround the openings 322c and 322d. The
slot 322 may be in fluid communication with the troughs between
ridges 311 of the adjacent main plate 370 (of FIG. 3E), such that
fluid flows from the openings 322c and 322d to the slots 332, to
the troughs between the ridges 311, to the slot 327, and from the
slot 327 to every trough to fill every space within the dead zone
371.
[0042] FIGS. 4A to 4C illustrate faying surfaces of end plates
according to embodiments of the present invention. The top end
plate 420 may correspond to the top end plate 120 of FIG. 1, and
the bottom end plate 430 may correspond to the bottom end plate 130
of FIG. 1.
[0043] FIG. 4A illustrates a top end plate 420 including a body 421
and a flange 422 extending downward and away from the body 421.
When an inward-facing surface 425 of the top end plate 420 defines
a first axis X, which may also be referred to for purposes of
description as horizontal axis X, a second axis Y, also referred to
as a vertical axis Y, is perpendicular to the horizontal axis X.
The flange 422 may extend outward from the body at an acute angle A
relative to the vertical axis Y. The inside surface 424 of the
flange 422, which is also referred to as the faying surface 424 may
be at an obtuse angle A1 relative to the inward-facing surface 425.
The flange 422 may also include a protrusion 423 at its end that
bends outward toward the horizontal axis X.
[0044] FIG. 4A also illustrates a main plate 410, which may
correspond to one of the main plates 110 of FIG. 1. As illustrated
in FIG. 4B, the main plate 410 is adjacent to the top end plate 420
and is configured to be bonded to the top end plate 420 on an
outside flange surface 413 and ridge peaks 414, such as by brazing.
The main plate 410 includes ridges 411 having peaks 414 and a
flange 412 extending downward from the ridges 414. A line passing
through a substantially center portion of each of the ridges 411
defines the horizontal axis X. The flange 412 extends downward from
the ridges 411 to be at an acute angle B relative to the vertical
axis Y, and at an obtuse angle B1 relative to the horizontal axis
X, as measured along an inside arc from an inside surface 414 of
the flange 412 to a portion of the axis X along the ridges 411. In
the present specification and claims, the angles A and B are also
referred to as draft angles A and B.
[0045] In one embodiment, the draft angle A is different than the
draft angle B. In particular, the draft angle A may be less than
the draft angle B, and the angle A1 may be less than the angle B1.
As illustrated in FIG. 4B, the top end plate 420 is configured to
be mounted onto the main plate 410, such that the inward-facing
surface 425 contacts the peaks 414 of the ridges 411 of the main
plate 410, while at the same time the inward-facing surface 424 of
the flange 422 contacts the outer surface 413 of the flange 412.
Since the draft angles A and B of the top end plate 420 and the
main plate 410 are dissimilar, a "line contact" is formed around
the periphery of the two flanges 422 and 412. When a braze melts
during a brazing operation, capillary action forces the braze to
"wick up" along the entire flange faying surfaces 413 and 424, thus
providing a highly reliable braze joint and hermetic seal. In other
words, since the draft angles A and B of the top end plate 420 and
the main plate 410 are dissimilar, the flange 422 does not contact
the flange 412 along an entire length of the flange 412, but only
along a narrow region that defines the line contact around an
entire circumference of the flange 412.
[0046] A similar feature is provided for the bottom end plate 430,
as illustrated in FIG. 4C. The bottom end plate 430 includes an
upper surface 432, or an inward-facing surface 432, which defines
the horizontal axis X. The vertical axis Y is perpendicular to the
horizontal axis X. An outer side or surface 431 of the bottom end
plate 430 has a draft angle C. A main plate 415 adjacent to the
bottom end plate 430 has ridges 416 with peaks 419 contacting the
inside-facing surface 432 of the bottom end plate 430. The main
plate 415 includes a flange 418 extending over the outer surface
431 of the bottom end plate 430 and having a draft angle D. In
embodiments of the present invention, the draft angle C is greater
than the draft angle D. As discussed above, since the draft angles
C and D of the bottom end plate 430 and the main plate 415 are
dissimilar, a "line contact" is formed around the periphery of the
outer surface 431 and the inner surface 417 of the flange 418. When
a braze melts during a brazing operation, capillary action forces
the braze to "wick up" along the entire flange faying surfaces 431
and 417, thus providing a highly reliable braze joint and hermetic
seal.
[0047] FIGS. 5A and 5B illustrate strengthening structures of a top
end plate 510 and a bottom end plate 530 according to embodiments
of the invention. The top end plate 510 and bottom end plate 530
may correspond to the top end plate 120 and bottom end plate 130,
respectively, of FIG. 1, for example.
[0048] Referring to FIG. 5A, the top end plate 520 includes an
outward-facing surface 511 and an inward-facing surface 512
opposite the outward-facing surface 511. The top end plate 520 is
made up of a thin layer 519, resulting in a top end plate 520
having a lighter weight. The top end plate 520 also includes thick
regions 517a and 517b around the openings 513, 514, 515 and 516.
The thick regions 517a and 517b are situated in areas that have
been predetermined to be subject to higher levels of stress during
operation of the plate heat exchanger. The top end plate 520 also
includes ribs 518 extending width-wise across the outward-facing
surface 511 to provide additional strength. Bosses 520 may be
formed along the ribs 518 for receiving mounting studs.
[0049] Referring to FIG. 5B the bottom end plate 530 includes an
outward-facing surface 531 and an inward-facing surface 532
opposite the outward-facing surface 531. The bottom end plate 530
is made up of a thin layer 539, resulting in a bottom end plate 530
having a lighter weight. The bottom end plate 530 also includes
thick regions 537a and 537b around the port regions 533, 534, 535
and 536. The thick regions 537a and 537b are situated in areas that
have been predetermined to be subject to higher levels of stress
during operation of the plate heat exchanger. The bottom end plate
530 also includes ribs 538 extending width-wise across the
outward-facing surface 511 to provide additional strength. Bosses
540 may be formed along the ribs 538 for receiving mounting
studs.
[0050] FIG. 6 illustrates the mounting of a stud 601 according to a
conventional configuration, and FIG. 7 illustrates a stud-mounting
portion of an end plate 700 according to one embodiment of the
invention. The end plate 700 may correspond to the top end plate
120 or bottom end plate 130 of FIG. 1, for example. Referring to
FIG. 6, in conventional plate heat exchangers, a stud 601 was
inserted into a hole in an outer plate 601 and was brazed or welded
to a seal plate 603. However, in conventional plate heat
exchangers, shifting of one of the plates 602 or 603 prior to
brazing, during brazing or after brazing may result in a bending or
tilting of the stud 601. Referring to FIG. 7, in embodiments of the
invention, a boss 704 or protrusion 704 is configured to protrude
from a base 703 of an end plate 700. The protrusion 704 has a shape
configured to receive the stud 701, such as a round inner shape of
a same size as a round outer shape of the stud 701. The base 703 of
the end plate 700 is the base of the receptacle defined by the
protrusion 704. Since the protrusion 704 extends outward from the
base 703 of the end plate 700, the stud 701 does not shift, bend or
tilt in the event that the end plate 700 shifts.
[0051] FIG. 8 illustrates a cut-away view of a portion of a top end
plate 820 and a fluid fitting 854 according to one embodiment. The
top end plate 820 may correspond to the top end plate 120 of FIG.
1, and the fluid fitting 854 may correspond to one of the fluid
fittings 151, 152, 153 or 154 of FIG. 1, for example.
[0052] The top end plate 820 includes a port defined by an inner
diameter surface made up of a lower portion 821, also referred to
as a pilot region 821 and an upper portion 822, also referred to as
a braze region 822. The top end plate 820 may be configured to be
attached to the main plate 810, and the main plate 810 may be
configured to be attached to the main plate 811. The inner diameter
surface of the top end plate 820 may be configured to receive the
fluid fitting 854 having an outer diameter surface 857. A recess
856 is formed in the outer diameter surface 857 of the fluid
fitting 854, the recess 856 defined by recess walls 855. The fluid
fitting 854 may also include a fluid channel 858.
[0053] In embodiments of the invention, the recess 856 is formed to
have a pre-defined size such that a predetermined amount of braze
material may be provided in the recess 856. The pilot region 821
has a diameter smaller than the braze region 822, such that the
pilot region 821 tightly or closely contacts the outer diameter
surface 857 while the braze region 822 defines a gap between a
surface of the braze region 822 and the outer diameter surface 857.
The thickness of the braze material between the outer diameter
surface 857 and the braze region 822 may be pre-determined and
controlled based on controlling the diameter of the braze region
822, thereby maintaining the strength of a braze joint.
[0054] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
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