Note: Descriptions are shown in the official language in which they were submitted.
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PLATE-TYPE HEAT EXCHANGER
FIELD OF THE INVENTION
This invention relates to plate-type heat exchangers for effecting heat
transfer
between two fluids, for example between a lubricating oil and a liquid
coolant.
BACKGROUND OF THE INVENTION
Plate-type heat exchangers comprising a stack of heat exchanger plates are
well
known. Such heat exchangers are commonly employed for effecting heat transfer
between a first fluid, for example a lubricating oil to be cooled, and a
second fluid, for
example a liquid coolant.
There is a need for improved heat exchangers of this type which are economical
to
manufacture and in which the heat transfer between the fluids is optimized.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a heat exchanger
comprising a plurality of first fluid core plates and a plurality of second
fluid core
plates, each of the core plates comprising a periphery; a first end; a second
end; a
generally flat base having a top surface and a bottom surface; a first fluid
inlet
opening proximate the first end of the plate; a first fluid outlet opening
spaced from
the first fluid inlet opening toward the second end of the plate; a second
fluid inlet
opening; and a second fluid outlet opening;
wherein the first fluid inlet and outlet openings are spaced from one another
along a plate axis and wherein the second fluid inlet and outlet openings are
located
on opposite sides of the plate axis;
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each of the first fluid core plates further comprises a first raised barrier
portion
having an upper surface which is raised relative to the top surface of the
base and
relative to the first fluid inlet and outlet openings, the first raised
barrier portion having
a first end proximate the first fluid inlet opening and a second end spaced
from the
first fluid inlet opening toward the second end of the plate, the second end
of the first
raised barrier portion being spaced toward the second end of the plate
relative to the
first fluid outlet opening, with a first fluid flow gap being provided between
the second
end of the first raised barrier portion and the second end of the plate
through which
the first fluid can flow between the first fluid inlet and outlet openings;
each of the first fluid core plates further comprises a first recessed barrier
portion having a lower surface which is recessed relative to the bottom
surface of the
base, with both the first fluid inlet and outlet openings being formed in the
first
recessed barrier portion, the first recessed barrier portion having a first
end proximate
the first end of the plate and a second end proximate the second end of the
plate,
wherein a second fluid flow gap is provided through which the second fluid can
flow
between the second fluid inlet and outlet openings, the second fluid flow gap
being
spaced toward the first end of the plate relative to at least one of the
second fluid
inlet and outlet openings;
each of the second fluid core plates further comprises a second raised barrier
portion having an upper- surface which is raised relative to the top surface
of the
base, with both the first fluid inlet and outlet openings of the second plate
being
formed in the second raised barrier portion, the second raised barrier portion
having
a first end proximate the first end of the plate and a second end proximate
the
second end of the plate, wherein a second fluid flow gap is provided through
which
the second fluid can flow between the second fluid inlet and outlet openings,
the
second fluid flow gap being spaced toward the first end of the plate relative
to at least
one of the second fluid inlet and outlet openings;
each of the second fluid core plates further comprises a second recessed
barrier portion having a lower surface which is recessed relative to the
bottom
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surface of the base and relative to the first fluid inlet and outlet openings,
the second
recessed barrier portion having a first end proximate the first fluid inlet
opening and a
second end spaced from the first fluid inlet opening toward the second end of
the
plate, the second end of the second recessed barrier portion being spaced
toward
the second end of the plate relative to the first fluid outlet opening, with a
first fluid
flow gap being provided between the second end of the second recessed barrier
portion and the second end of the plate through which the first fluid can flow
between
the first fluid inlet and outlet openings;
the first fluid core plates and the second fluid core plates being in
alternating
stacked relationship with the periphery of each first fluid core plate being
sealed to
the periphery of an adjacent second fluid core plate to form a plurality of
fluid flow
passages;
said plurality of fluid flow passages comprising a plurality of first fluid
flow
passages for flow of the first fluid, each of the first fluid flow passages
being formed
between the top surface of a first fluid core plate and the bottom surface of
an
upwardly adjacent second fluid core plate, with the upper surface of the first
raised
barrier portion of the first fluid core plate being in sealed contact with the
lower
surface of the second recessed barrier portion of the second fluid core plate
and with
the gap of the first raised barrier portion communicating with the gap of the
second
recessed barrier portion, such that the first fluid can flow from the first
fluid inlet
opening, through the first fluid flow passage, and through the gaps to the
first fluid
outlet opening;
said plurality of fluid flow passages further comprising a plurality of second
fluid flow passages for flow of the second fluid, each of the second fluid
flow
passages being formed between the top surface of a second fluid core plate and
the
bottom surface of an upwardly adjacent first fluid core plate, with the upper
surface of
the second raised barrier portion of the second fluid core plate being in
sealed
contact with the lower surface of the first recessed barrier portion of the
first fluid core
plate and with the gap of the second raised barrier portion communicating with
the
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gap of the first recessed barrier portion, such that the second fluid can flow
from the
second fluid inlet opening, through the second fluid flow passage, and through
the
gaps to the second fluid outlet opening;
wherein the first fluid flow passages alternate with the second fluid flow
passages.
It will be appreciated that alternatively the first fluid may flow in the
reverse direction
through the first fluid flow passage in which case the first fluid outlet
openings in the
plates would function as first fluid inlet openings, and the first fluid inlet
openings in
the plates would function as first fluid outlet openings.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be more clearly understood and more readily
carried
into effect, the same will now, by way of example, be more fully described
with
reference to the accompanying drawings in which:
Figure 1 is a top perspective view of an oil core plate of a heat exchanger
according
to a preferred embodiment of the invention;
Figure 2 is a bottom perspective view of the oil core plate shown in Figure 1;
Figure 3 is a top perspective view of a coolant core plate of the heat
exchanger
according to a preferred embodiment of the invention;
Figure 4 is a bottom perspective view of the coolant core plate shown in
Figure 3;
Figure 5 is a top plan view of the oil core plate shown in Figures 1 and 2;
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Figure 6 is a bottom plan view of the oil core plate shown in Figures 1 and 2;
Figure 7 is a top plan view of the coolant core plate shown in Figures 3 and
4;
Figure 8 is a bottom plan view of the coolant core plate shown in Figures 3
and 4;
Figure 9 is a cross sectional view of a heat exchanger according to a
preferred
embodiment of the invention comprising a stack of oil core plates as shown in
Figures 1, 2, 5 and 6 and a plurality of coolant core plates as shown in
Figures 3, 4, 7
and 8, with the oil core plates being sectioned along line 9-9 in Figure 5 and
the
coolant core plates being sectioned along line 9'-9' in Figure 7; and
Figure 10 is a further cross sectional view of the heat exchanger shown in
Figure 9,
with the oil core plates being sectioned along line 10-10 in Figure 5 and the
coolant
core plates being sectioned along line 10'-10' in Figure 7.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The preferred embodiment of the invention relates to a plate-type heat
exchanger for
effecting heat transfer between a first fluid to be cooled and a second fluid.
The first
fluid may preferably comprise a lubricating oil such as natural or synthetic
engine oil,
transmission oil or power steering oil or other fluid to be cooled, such as
fuel. The
second fluid may preferably comprise a liquid coolant for cooling the oil in
the heat
exchanger, for example a glycol coolant. Alternatively, at least one of the
first and
second fluids could be, for example, water, deionized waiter, or refrigerant,
the fluid
being in liquid, gaseous"or two-phase form. In the following detailed
description, the
first and second fluids are referred to as the oil and the coolant,
respectively and are
in liquid form.
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Terms such as "top", "bottom", "upward", "downward", "raised", "recessed" and
the
like are used herein as terms of reference to describe features of the heat
exchangers and heat exchanger plates according to the invention. It will be
appreciated that these terms are used for convenience only, and the heat
exchangers and heat exchanger plates according to the invention can have any
desired orientation when in use.
The oil core plate 10 is now described in detail below with reference to
Figures 1, 2, 5
and 6. Oil core plate 10 comprises a generally flat, planar base 12 having a
top
surface 14 and a bottom surface 16. In the preferred embodiment of the
invention,
the periphery 18 of plate 10 is provided with an upstanding flange 20, this
flange 20
being outwardly inclined in a direction away from the base 12, such that there
is an
obtuse angle between the flange 20 and the adjacent portion of base 12. The
base
12 has an oil inlet opening 22 proximate a first end 24 of plate 10 and an oil
outlet
opening 26 spaced from the oil inlet opening 22 toward a second end 28 of
plate 10.
The oil inlet and outlet openings 22, 26 are spaced from one another along a
plate
axis P which, in the preferred embodiment shown in the drawings,
longitudinally
bisects the plate 10. It will, however, be appreciated that the axis P does
not
necessarily bisect the plate 10.
Plate 10 further comprises a coolant inlet opening 30 and a coolant outlet
opening 32
together with, in the preferred embodiment shown in the drawings, a further
opening
34 located between the.oil inlet and outlet openings 22, 26. The coolant inlet
and
outlet openings 30, 32 are preferably located on opposite sides of the plate
axis P,
and are preferably located proximate the second end 28 of the plate 10. The
further
opening 34, the purpose of which will be explained later, is preferably
located
between the oil inlet and outlet openings 22, 26, preferably in close
proximity to
openings 22, 26 and preferably located along the plate axis P.
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The base 12 of oil core plate 10 is provided with a plurality of protrusions
and
depressions in order to direct flow of the heat exchange fluids along its top
and
bottom surfaces 14, 16. In particular, the core plate 10 is provided with
features
which protrude in opposite directions from its top and bottom surfaces 14, 16.
For
consistency with the terms of reference used to describe the relative
orientations of
the plates, the features which protrude from the top surface 14 of the base 12
are
described as "raised", while those protruding from the bottom surface 16 are
described as "depressed". Again, it will be appreciated that these terms are
used for
convenience only. These features of the oil core plate 10 are now described in
detail
below.
As shown in Figures 1 and 5, the top surface 14 of base 12 is provided with a
first
raised barrier portion 36 having an upper surface 38 which is raised relative
to the top
surface 14 of base 12 and relative to the oil inlet and outlet openings 22,
26. The
function of the first raised barrier portion 36 is to direct the flow of oil
along the top
surface 14 of base 12 between the oil inlet and outlet openings 22, 26 in a
manner
which maximizes the use of the plate surface area and thereby provides optimal
heat
transfer with the coolant. This will be described in detail below.
The first raised barrier portion 36 has a first end 40 proximate the oil inlet
opening 22
and a second end 42 spaced from the oil inlet opening 22 toward the second end
28
of plate 10. An oil flow gap 44 is preferably provided between the second end
42 of
first raised barrier portion 36 and the second end 28 of the plate 10, through
which oil
can flow between the oil inlet and outlet openings 22, 26, as explained in
detail
below.
As shown in Figures 2 and 6, the bottom surface 16 of base 12 is provided with
a first
recessed barrier portion 46 having a lower surface 48 which is recessed
relative to
the bottom surface 16. The function of the first recessed barrier portion 46
is to direct
the flow of coolant along the bottom surface 16 of base 12 between the coolant
inlet
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and outlet openings 30, 32 in a manner which optimizes heat transfer with the
oil.
This is described in detail below.
The first recessed barrier portion 46 has a first end 50 proximate the first
end 24 of
plate 10 and a second end 52 proximate the second end 28 of plate 10. Both the
oil
inlet and outlet openings 22, 26 are formed in the lower surface 48 of the
first
recessed barrier portion 46, with the oil inlet opening 22 preferably being
located
proximate the first end 50 of barrier portion 46 and the oil outlet opening 26
preferably being located intermediate the first and second ends 50, 52 of
barrier
portion 46.
Preferably, as shown in the drawings, the first recessed barrier portion 46
extends
along the plate axis P, with the coolant inlet and outlet openings 30, 32
being located
on opposite sides of the barrier portion 46. At least one coolant flow gap is
provided,
either through the first recessed barrier portion 46 or between the barrier
portion 46
and the first end 24 of plate 10, through which the coolant can flow generally
transversely as it flows between the coolant inlet and outlet openings 30, 32.
In the
preferred embodiment shown in the drawings, a first coolant flow gap 54 is
provided
between the first end 50, of the first recessed barrier portion 46 and the
first end 24 of
plate 10, through which the coolant can flow between the coolant openings 30,
32.
To maximize the length of the coolant flow path along the bottom surface 16 of
base
12, and thereby optimize heat transfer, the coolant flow gap 54 is spaced
toward the
first end 24 of plate 10 relative to the coolant openings 30, 32, and
preferably the
coolant flow gap 54 and coolant openings 30, 32 are located at opposite ends
of
plate 10.
The coolant core plate 60 is now described in detail below with reference to
Figures
3, 4, 7 and 8. Coolant core plate 60 comprises a generally flat, planar base
62
having a top surface 64 and a bottom surface 66. In the preferred embodiment
of the
CA 02485036 2004-10-19
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invention, the periphery.68 of plate 60 is provided with an upstanding flange
70, this
flange 70 being outwardly inclined in a direction away from the base 62, such
that
there is an obtuse angle between the flange 70 and the adjacent portion of
base 62.
The base 62 has an oil inlet opening 72 proximate a first end 74 of plate 60
and an oil
outlet opening 76 spaced from the oil inlet opening 72 toward a second end 78
of
plate 60, preferably along plate axis P.
Plate 60 further comprises a coolant inlet opening 80 and a coolant outlet
opening 82
together with, in the preferred embodiment shown in the drawings, a further
opening
84 located between the oil inlet and outlet openings 72, 76. The purpose of
opening
84 will be explained in detail later. The coolant inlet and outlet openings
80, 82 are
preferably located on opposite sides of the plate axis P, and are preferably
located
proximate the second end 78 of the plate 60. The further opening 84 is
preferably
located between the oil inlet and outlet openings 72, 76, preferably in close
proximity
to openings 72, 76 and preferably located along the plate axis P.
The base 62 of coolant core plate 60 is provided with a plurality of
protrusions and
depressions in order to direct flow of the heat exchange fluids along its top
and
bottom surfaces 64, 66. In particular, the core plate 60 is provided with
features
which protrude in opposite directions from its top and bottom surfaces 64, 66.
As
with the oil core plate, the features which protrude from the top surface 64
of the
coolant core plate 60 are described as "raised", while those protruding from
the
bottom surface 66 are described as "depressed". Again, it will be appreciated
that
these terms are used for convenience only. These features of the coolant core
plate
60 are now described in detail below.
As shown in Figures 3 and 7, the top surface 64 of base 62 is provided with a
second
raised barrier portion 86 having an upper surface 88 which is raised relative
to the top
surface 64. The function of the second raised barrier portion 86 is to direct
the flow
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of coolant along the top surface 64 of base 62 between the coolant inlet and
outlet
openings 80, 82 in a manner which optimizes heat transfer with the oil. This
is
described in detail below.
The second raised barrier portion 86 has a first end 90 proximate the first
end 74 of
plate 60 and a second end 92 proximate the second end 78 of plate 60. Both the
oil
inlet and outlet openings 72, 76 are formed in the upper surface 88 of the
second
raised barrier portion 86, with the oil inlet opening 72 preferably being
located
proximate the first end 80 of barrier portion 86 and the oil outlet opening 76
preferably being located intermediate the first and second ends 90, 92 of
barrier
portion 86.
Preferably, as shown in the drawings, the second raised barrier portion 86
extends
along the plate axis P, with the coolant inlet and outlet openings 80, 82
being located
on opposite sides of the. barrier portion 86. At least one coolant flow gap is
provided,
either through the second raised barrier portion 86 or between the barrier
portion 86
and the first end 74 of plate 60, through which the coolant can flow generally
transversely as it flows between the coolant inlet and outlet openings 80, 82.
In the
preferred embodiment shown in the drawings, a first coolant flow gap 94 is
provided
between the first end 90 of the second raised barrier portion 86 and the first
end 74
of plate 60, through which the coolant can flow between the coolant openings
80, 82.
To maximize the length of the coolant flow path along the top surface 64 of
base 62,
and thereby optimize heat transfer, the coolant flow gap 94 is spaced toward
the first
end 74 of plate 60 relative to the coolant openings 30, 32, and preferably the
coolant
flow gap 94 and coolant openings 80, 82 are located at opposite ends of plate
60.
As shown in Figures 4 and 8, the bottom surface 66 of base 62 is provided with
a
second recessed barrier portion 96 having a lower surface 98 which is recessed
relative to the bottom surface 66 of base 62 and relative to the oil inlet and
outlet
openings 72, 76. The function of the second recessed barrier portion 96 is to
direct
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the flow of oil along the bottom surface 66 of base 62 between the oil inlet
and outlet
openings 72, 76 in a manner which optimizes heat transfer with the coolant.
This will
be described in detail below.
The second recessed barrier portion 96 has a first end 100 proximate the oil
inlet
opening 72 and a second end 102 spaced from the oil inlet opening 72 toward
the
second end 78 of plate 60. An oil flow gap 104 is preferably provided between
the
second end 102 of second recessed barrier portion 96 and the second end 78 of
the
plate 60, through which oil can flow between the oil inlet and outlet openings
72, 76,
as explained in detail below.
It will be appreciated from the drawings that the first raised barrier portion
36 of the oil
core plate 10 and the second recessed barrier portion 96 of coolant core plate
60
correspond in size, shape and location so that their respective upper and
lower
surfaces 38 and 98 are in sealed contact with one another in the assembled
heat
exchanger. Preferred features of first raised barrier portion 36 are now
described
below with reference to the drawings. Except where noted to the contrary, the
following discussion also applies to the second recessed barrier portion 96 of
plate
60, and corresponding features of the second recessed barrier portion 96 are
identified in the drawings with corresponding, primed reference numerals.
Firstly, it will be noted from Figures 1 and 5 that the first raised barrier
portion 36
comprises a first portion 106 and a pair of legs 108, 110. The first portion
106 of
barrier portion 36 is located between the oil inlet and outlet openings 22, 26
and
includes the first end 40 of barrier portion 36. In the preferred embodiment
shown in
the drawings, the first portion 106 of barrier portion 36 comprises a raised,
approximately circular rib surrounding the further opening 34 of oil core
plate 10, the
outer periphery of the rib being in close proximity to both the oil inlet and
outlet
openings 22, 26.
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As shown in the drawings, the legs 108, 110 of first raised barrier portion 36
extend
from the first portion106 of barrier portion 36 toward the second end 28 of
plate 10.
Preferably, the terminal ends 112, 114 of legs 108, 11 C) are located at the
second
end 42 of barrier portion 36 and are proximate to the second end 28 of plate
10, with
the oil flow gap 44 being defined by the distance (measured parallel to axis
P)
between the terminal ends 112, 114 of the legs 108, 110 and the second end 28
of
plate 10.
Preferably, the legs 108, 110 extend along opposite sides of the oil outlet
opening 26
for at least a portion of their lengths and are spaced apart so as to define a
channel
116. With an axial distance from the terminal ends 112, 114 of legs 108, 110
and the
second end 28 of plate 10 preferably being less than an axial distance between
the
oil outlet opening 26 and the second end 28 of plate 10, the channel 116
provides a
flow path extending from gap 44 toward the first end of plate 10, along which
the oil
must flow in order to reach the oil outlet opening 26. This has the effect of
lengthening the flow path between the oil inlet and outlet openings 22, 26,
thereby
maximizing use of the plate surface area and optimizing heat transfer.
Preferably, the channel 116 is coplanar with the first fluid outlet opening 26
and with
the first recessed barrier portion 46, i.e. it is recessed relative to the
base 12. In the
preferred embodiment shown in the drawings, the channel 116 preferably extends
continuously along axis P from the oil outlet opening 26 to the second end 28
of plate
10.
As shown in the drawings, a pair of grooves 118 and 120 is formed in the top
surface
14 of plate 10. Each groove 118, 120 extends along a side of one of the legs
108,
110 opposite the channel 116. Preferably, the grooves 118, 120 are coplanar
with
the channel 116 and each have an end communicating with the channel 116 at the
terminal end 112 or 114 of one of the legs 108 or 110.
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Lastly, the base 12 of oil core plate 10 is provided on its top surface 14
with a pair of
upstanding bosses 122, 124 having respective upper surfaces 126, 128 in which
the
coolant inlet and outlet openings 30, 32 are formed. In the preferred
embodiment
shown in the drawings, the upper surfaces 126, 128 of bosses 122, 124 are
raised
relative to the base 12 and relative to the first raised barrier portion 36,
with the
corresponding coolant inlet and outlet openings 80, 82 of the coolant core
plate 60
being coplanar with the base 62 thereof. It will, however, be appreciated that
this is
not necessarily the case. For example, the upper surfaces 126, 128 of raised
bosses
122, 124 could be coplanar with the upper surface 38 of raised barrier portion
36,
and the coolant core plate could be provided with corresponding recessed
bosses
(not shown) which come into sealed contact with the raised bosses 122, 124.
It will further be appreciated from the drawings that the first recessed
barrier portion
46 of the oil core plate 10 and the second raised barrier portion 86 of
coolant core
plate 60 correspond in size, shape and location so that their respective lower
and
upper surfaces 48 and 88 are in sealed contact with one another in the
assembled
heat exchanger. Preferred features of first recessed barrier portion 46 are
now
described below with reference to the drawings. Except where noted to the
contrary,
the following discussion also applies to the second raised barrier portion 86
of plate
60, and corresponding features of the second raised barrier portion 86 are
identified
in the drawings with corresponding, primed reference numerals.
It will be noted that the first recessed barrier portion 46 is comprised of a
plurality of
bosses, including a first boss 130 in which the oil inlet opening 22 is formed
and a
second boss 132 in which the oil outlet opening 26 is formed. In preferred
embodiments where the plate 10 includes a further opening 34, the barrier
portion 46
further comprises a third boss 134 located between and in close proximity to
the first
and second bosses 130, 132. The third boss 134 surrounds the further opening
34
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and is located radially inwardly of the approximately circular rib comprising
the first
portion 106 of the first raised barrier portion 36, discussed above.
As shown in the drawings, the first coolant flow gap 54 is located between the
first
boss 130 and the first end 24 of plate 10. In addition a second coolant flow
gap 136
is located between the first boss 130 and the third boss 134, and a third
coolant flow
gap 138 is located between the second boss 132 and the third boss 134. The
first
gap 54 is preferably wider than the second and third gaps 136, 138 so that
most of
the coolant flowing from. the coolant inlet opening 30 to the coolant outlet
opening 32
will be forced to flow around the first boss 130, thereby maximizing the
distance
travelled by the coolant and maximizing use of the plate surface area, thereby
optimizing heat transfer.
As shown in the drawings, the second boss 132 is elongate and extends axially
from
the oil outlet opening 26 to the second end 28 of plate 110, thereby
preventing short
circuit flow of coolant across the plate between inlet and outlet openings 30,
32. It
will also be appreciated that the second boss is coextensive with the recessed
channel 116, discussed above, which is formed in the top surface 14 of plate
10.
The first recessed barrier portion 46 further comprises a pair of legs 140,
142 to help
direct flow of the coolant. These legs 140, 142 extend alongside and in close
proximity to the second boss 132 and are coincident with the grooves 118, 120
on
the other side of the plate 10. Each of the legs 140, 142 has a free end which
terminates proximate the third coolant flow gap 138 and an opposite end which
is
joined to a side of the second boss 132. The legs 140, 142 are spaced from the
second boss 132 by a pair of narrow grooves 144, 146, comprising the
undersides of
the legsl08, 110 formed in the top surface 14 of plate 10. The grooves 144,
146 are
preferably coplanar with a groove 148 surrounding the third boss 134, which
forms
the underside of the first portion 106 of the first raised barrier portion 36,
described
above.
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Referring now to Figures 9 and 10 of the drawings, there is illustrated a heat
exchanger 150 according to the invention comprising a plurality of oil core
plates 10
and a plurality of coolant core plates 60 which are comprised of one or more
metals
such as aluminum, stainless steel or copper alloy. Alternatively, the plates
could
comprise a non-metallic material such as plastic, preferably having high
thermal
conductivity. The plates 10, 60 are disposed in alternating stacked
relationship, with
all plates 10, 60 facing the same direction and with the flanges 20, 70 of
adjacent
plates 10, 60 being in sealed nested contact with one another, thereby sealing
together the peripheries 18, 68 of adjacent core plates 10, 60. In the
drawings, all
plates 10, 60 of heat exchanger 150 are shown facing upwardly and, with the
exception of the plates at the top and bottom of the heat exchanger, each oil
core
plate 10 has its top surface 14 facing the bottom surface 66 of an upwardly
adjacent
coolant core plate 60 and each coolant core plate 60 has its top surface 64
facing the
bottom surface 16 of an upwardly adjacent oil core plate 10. Only some of the
plates
comprising heat exchanger 150 are shown in the drawings.
The bases 12, 62 of alternating oil and coolant core plates 10, 60 are in
spaced
relation to one another to define a series of alternating oil flow passages
152 and
coolant flow passages 154. Oil flow passages 152 are formed between the top
surfaces 14 of oil core plates 10 and the bottom surfaces 66 of upwardly
adjacent
coolant core plates 60. Similarly, coolant flow passages 154 are formed
between the
top surfaces 64 of coolant core plates 60 and the bottom surfaces 16 of
upwardly
adjacent oil core plates 10.
It will be seen from the drawings of heat exchanger 150 that the first raised
barrier
portions 36 of the oil core plates 10 are in sealed contact with the
corresponding
second recessed barrier portions 96 of an upwardly adjacent coolant core plate
60,
the barrier portions 36, 96 being in sealed contact along their upper and
lower
surfaces 38, 98, respectively. As mentioned above, the barrier portions 36, 96
are
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preferably identical in size and shape and are of sufficient height so that
each raised
element making up barrier portion 36 (i.e. first portion 106 and legs 108,
110) is in
sealed contact with a corresponding recessed element of barrier portion 96
(i.e. first
portion 106' and legs 108', 110'). Furthermore, the oil flow gaps 44 and 104
of the
respective oil and coolant core plates 10, 60 are aligned, as are the channels
116,
116' and the grooves 118, 118', 120 and 120' of respective plates 10, 60.
It will also be seen that the second raised barrier portions 86 of the coolant
core
plates 60 are in sealed contact with the corresponding first recessed barrier
portions
46 of an upwardly adjacent oil core plate 10, the barrier portions 86, 46
being in
sealed contact along their upper and lower surfaces 88, 48, respectively. The
barrier
portions 46, 86 are preferably identical in size, shape and height so that
each
recessed element making up barrier portion 46 (i.e. first boss 130, second
boss 132,
third boss 134 and legs 140, 142) is in sealed contact with a corresponding
raised
element of barrier portion 86 (i.e. first boss 130', second boss 132', third
boss 134'
and legs 140', 142'). Furthermore, the first coolant flow gaps 54 and 94 of
the
respective oil and coolant core plates 10, 60 are aligned, as are the second
coolant
flow gaps 136, 136', the third coolant flow gaps 138, 138' and the narrow
grooves
144, 144', 146 and 146' of the respective plates 10, 60.
It will also be appreciated that the bosses 122, 124 formed in the top surface
14 of
each oil core plate 10, in which the coolant inlet and outlet openings 30, 32
are
formed, are sealed along their upper surfaces 126, 128 to the bottom surface
66 of
an upwardly adjacent coolant core plate 60. Furthermore, the plates 10, 60 are
sealed together with the openings of each oil core plate 10 (i.e. oil inlet
opening 22,
oil outlet opening 26, coolant inlet opening 30, coolant outlet opening 32,
further
opening 34) being in alignment with the corresponding openings of each coolant
core
plate 60 (i.e. oil inlet opening 72, oil outlet opening 76, coolant inlet
opening 80,
coolant outlet opening 82, further opening 84).
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Where the plates are made of a metallic material, they may be provided with a
brazing filler metal in the form of a cladding, a coating or. shim plates so
that, after
assembly of the plurality of oil core plates 10 and the plurality of coolant
core plates
60 as described above, the assembled plates 10, 60 may be disposed in a
brazing
furnace or other suitable heating means thereby to provide the above-described
sealing contact between the plates 10, 60. Metallic plates can also be joined
by
alternate suitable means such as welding, adhesive bonding, or mechanical
assembly using sealing gaskets. Non-metallic plates can be joined by other
means,
such as ultrasonic welding.
Ends plates 156 and 158 are schematically shown in the drawings for sealing
the
ends of the plate stack and connecting it to the oil and coolant systems.
Figure 9
shows lower end plate 158 being provided with a coolant inlet opening 160 and
a
coolant inlet fitting 162, and also with a coolant outlet opening 164 and a
coolant
outlet fitting 166. The coolant inlet opening 160 of plate 158 is in
communication with
the coolant flow passages 154 and is aligned with the coolant inlet openings
30, 80 of
the stacked plates 10, 60. Similarly, the coolant outlet opening 164 of plate
158 is in
communication with the coolant flow passages 154 and is aligned with the
coolant
outlet openings 32, 82 of the plates 10, 60. The aligned inlet openings 30, 80
and
aligned outlet openings 32, 82 are closed at the upper end of heat exchanger
150 by
the upper end plate 158.
As shown in Figure 10, the lower end plate 158 may preferably be mounted to an
engine block 168 and the upper end plate may preferably be mounted to an oil
filter
170. The lower end plate 158 is provided with an oil inlet opening 172 through
which
oil enters the heat exchanger 150 from an internal flow passage 174 in the
engine
block 168. The oil inlet opening 172 of lower end plate 158 is in
communication with
oil flow passages 152 and is aligned with the oil inlet openings 22, 72 of the
stacked
plates 10, 60. The upper end plate 156 is provided with an oil outlet opening
176
which is in communication with an inlet opening 178 of the oil filter 170. The
oil outlet
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opening 176 is also in communication with oil flow passages 152 and is aligned
with
the oil outlet openings 26, 76 of the plates 10, 60.
The upper end plate 156 is also provided with an oil return opening 180
through
which filtered oil is returned to the engine block 168 via the aligned further
openings
34, 84 of the stacked plates 10, 60 which together form an oil return passage
182
which is sealed from the oil flow passages 152. The oil return passage 182 is
in
communication with an oil return opening 184 in the lower end plate 158 and
with an
oil return passage 186 of the engine block 168.
In operation, oil from engine block 168 enters the heat exchanger 150 through
the oil
inlet opening 172 in the lower end plate 158 and then flows into one end of
the
aligned oil inlet openings 22, 72. Since the other end of the aligned openings
22, 72
is blocked by upper end plate 156, the oil is forced to flow through the oil
flow
passages 152 as indicated in chain-dotted lines in Figure 5. In order to flow
from the
oil inlet opening 22 to the oil outlet opening 26, the oil must flow alongside
the first
raised barrier portion 36 toward the second end 28 of plate 10, through oil
flow gap
44 and along channel 116 to oil outlet opening 26. Therefore, the oil must
flow over
a substantial portion of the base 12 of each plate 10 as it flows from the oil
inlet
opening 22 to the oil outlet opening 26.
The oil flowing from the heat exchanger through the aligned oil outlet
openings 26, 76
flows through the oil outlet opening 176 in the upper end plate 156 and into
oil filter
170 where it passes through a filter medium 188 and enters a perforated
central tube
190 for return to the engine block 168 through the oil return passage 182 and
the oil
return openings 180, 184. The flow of oil through the engine block 168, heat
exchanger 150 and oil filter 170 is indicated by arrows in Figure 10. In this
embodiment, it will be appreciated that the oil is cooled before it is
filtered.
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In the alternative, the oil flow may be reversed so that it is filtered before
being cooled
by heat exchanger 150. In this embodiment, the oil flows from passage 186 of
engine block 168 into the passage 182 of heat exchanger 150. The oil flows
through
passage 182 and enters the oil filter 170 to be filtered. The filtered oil
then enters the
heat exchanger 150 through opening 176 in upper end plate 156 and exits the
heat
exchanger through the opening 172 in the lower end plate 158, returning to
engine
block 168 through passage 174.
In the preferred heat exchanger 150 shown in Figure 10, the aligned inlet
openings
22, 72 are sealed from direct flow communication with the oil filter 170 under
all
operating conditions, i.e. the oil must pass through the oil flow passages 152
before
entering the oil filter 170. It may be preferred to provide a further opening
(not
shown) in the upper end plate 156 which is aligned with the inlet openings 22,
72 of
plates 10, 60 and which is provided with a by-pass valve (not shown), for
example an
active pressure or thermal relief valve, to permit oil to by-pass the heat
exchanger
under start-up conditions and directly enter the oil filterr. Such by-pass
valves are
known in the art and do not form part of the present invention. Alternatively,
it may
be preferred to provide a passive by-pass orifice, in the form of a calibrated
opening
in the upper end plate 156, so as to permit controlled flow of fluid to the
oil filter under
various conditions.
As shown in Figure 9, coolant enters the heat exchanger 150 through a coolant
inlet
opening 160 in the lower end plate 158 and then flows into one end of the
aligned
coolant inlet openings 30, 80. Since the other end of the aligned openings 30,
80 is
blocked by upper end plate 158, the coolant is forced to flow through the
coolant flow
passages 154 following the path indicated in chain-dotted lines in Figure 7.
In order
to flow from the coolant inlet opening 30 to the coolant outlet opening 32,
the coolant
must flow along one side of the second raised barrier portion 86 toward the
first end
24 of plate 10, through the first coolant flow gap 54, then alongside the
other side of
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barrier portion 86 toward the second end 28 of plate 10, to the coolant outlet
opening
32. Therefore, the coolant must flow over a substantial portion of the base 62
of
each coolant core plate 60 as it flows from the coolant inlet opening 30 to
the coolant
outlet opening 32. It will be appreciated that a relatively small amount of
coolant will
flow through the second and third coolant flow gaps 136, 138, but this has a
minimal
impact on the performance of heat exchanger 150.
The heat exchanger 150 according to the invention thus achieves a high rate of
heat
transfer between the oil and the coolant. It will, of course, be appreciated
that the
openings 32, 82 could be the coolant inlet openings with the openings 30, 80
being
the coolant outlet openings. Furthermore, the openings 26, 76 could function
as the
oil inlet openings, with the openings 22, 72 functioning as the oil outlet
openings.
It will be appreciated that the height of each oil flow passage 152 and the
height of
each coolant flow passage 154 is partly dependent on the extent of the nesting
of the
alternate plates 10, 60 and therefore is partly dependent on the angle of
inclination of
the flanges 20, 70. It will also be appreciated that the heights of the flow
passages
152, 154 are also partly dependent on the heights of the barrier portions 36,
46, 86,
96 and the heights of bosses122, 124.
Turbulisers which may be of conventional form, such as the turbulisers 60 of
U.S.
Patent No. 6,244,334 issued on June 12, 2001 to Wu, et at., are preferably
disposed
in one or more of the oil-flow passages 152 and may also be disposed in one or
more
of the coolant flow passages 154, these turbulisers serving to disrupt the oil
or
coolant flow in each of the oil or coolant flow passages 152, 154 in which
they are
installed and to disturb the boundary layers of the oil or coolant flow at the
surfaces of
the plates 10, 60, thereby improving the efficiency of heat transfer from the
oil to the
coolant in the heat exchanger 150. For clarity, these turbulisers are shown
only in
Figures 5 and 7 and only in outline denoted by broken lines 178, 180. The
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turbulisers 178, 180 have a high pressure drop (HPD) flow direction in which
maximum turbulising of the oil flow occurs but with a high pressure drop in
the oil
flow, and a transverse low pressure drop (LPD) flow direction in which there
is
reduced turbulising of the oil flow but with low pressure drop in the oil
flow. As
desired, the turbulisers 178, 180 may each be disposed in either the HPD or
LPD
flow direction.
Instead of using turbulisers 178, 180, the base 62 of one or more of the
coolant core
plates 60 may be formed with spaced protrusions such as ribs and/or dimples,
similar
to those shown in Figures 1 and 2 of U.S. Publication No. 2004/0040697 Al (St.
Pierre et al.) published on March 4, 2004.
Although the invention has been described in connection with certain preferred
embodiments, it is not limited thereto. Rather, the invention includes all
embodiments which may fall within the scope of the following claims.
