U.S. patent application number 14/569881 was filed with the patent office on 2015-06-18 for heat recovery device with standoff heat exchanger mount.
The applicant listed for this patent is Dana Canada Corporation. Invention is credited to Brian E. Cheadle, Ihab Edward Gerges.
Application Number | 20150167519 14/569881 |
Document ID | / |
Family ID | 53367819 |
Filed Date | 2015-06-18 |
United States Patent
Application |
20150167519 |
Kind Code |
A1 |
Gerges; Ihab Edward ; et
al. |
June 18, 2015 |
HEAT RECOVERY DEVICE WITH STANDOFF HEAT EXCHANGER MOUNT
Abstract
A heat recovery device comprises a gas flow conduit, a
gas/liquid heat exchanger and a gas diverter valve provided in the
gas flow conduit, the valve being movable between a bypass position
and a heat exchange position. The gas flow conduit includes a
divergent branch point at which it is divided into a bypass branch
conduit and a heat exchange branch conduit. The bypass branch
conduit bypasses the heat exchanger, and the heat exchange branch
conduit includes an upstream conduit portion and a downstream
conduit portion. The gas flow direction from the upstream conduit
portion into the gas inlet opening of the heat exchanger diverges
in a direction away from the overall gas flow direction, permitting
the heat exchanger to be spaced away from the exhaust gas
conduit.
Inventors: |
Gerges; Ihab Edward;
(Oakville, CA) ; Cheadle; Brian E.; (Brampton,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dana Canada Corporation |
Oakville |
|
CA |
|
|
Family ID: |
53367819 |
Appl. No.: |
14/569881 |
Filed: |
December 15, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61916336 |
Dec 16, 2013 |
|
|
|
Current U.S.
Class: |
165/104.19 |
Current CPC
Class: |
F01N 2410/00 20130101;
F01N 2240/02 20130101; Y02T 10/20 20130101; Y02T 10/12 20130101;
Y02T 10/16 20130101; F01N 3/0205 20130101; F01N 2240/36 20130101;
F01N 5/02 20130101 |
International
Class: |
F01N 3/04 20060101
F01N003/04 |
Claims
1. A heat recovery device, comprising: a gas flow conduit having an
inlet and an outlet, wherein an overall gas flow direction through
the gas flow conduit is defined between the inlet and the outlet
thereof; a gas/liquid heat exchanger having a gas inlet opening and
a gas outlet opening; a gas diverter valve provided in the gas flow
conduit, wherein the valve is movable between a bypass position and
a heat exchange position; wherein the gas flow conduit includes a
divergent branch point at which the gas flow conduit is divided
into a bypass branch conduit and a heat exchange branch conduit;
wherein the bypass branch conduit bypasses the heat exchanger, and
the heat exchange branch conduit includes an upstream conduit
portion and a downstream conduit portion; wherein the upstream
conduit portion has a first end in flow communication with said gas
flow conduit at said divergent branch point, and a second end in
flow communication with the gas inlet opening of the heat
exchanger; wherein the downstream conduit portion has a first end
in flow communication with the gas outlet opening of the heat
exchanger; and wherein a gas flow direction into the gas inlet
opening of the heat exchanger diverges in a direction away from the
overall gas flow direction through the gas flow conduit.
2. The heat recovery device of claim 1, further comprising a
convergent branch point at which the bypass branch conduit and the
heat exchange branch conduit converge, the convergent branch point
being located upstream of the outlet of the gas flow conduit.
3. The heat recovery device of claim 2, wherein the downstream
conduit portion has a second end in flow communication with the gas
flow conduit at the convergent branch point.
4. The heat recovery device of claim 1, wherein a first plane
passes through the inlet and outlet of the gas flow conduit, the
first branch point and the bypass branch conduit.
5. The heat recovery device of claim 4, wherein a second plane
passes through the second end of the upstream conduit portion and
the first end of the downstream conduit portion, and wherein
portions of the first and second planes passing through heat
recovery device are spaced apart from one another.
6. The heat recovery device of claim 5, wherein the second end of
the upstream conduit portion and the first end of the downstream
conduit portion are secured to the heat exchanger at the respective
gas inlet opening and gas outlet opening, in said second plane.
7. The heat recovery device of claim 4, wherein the upstream
conduit portion and the downstream conduit portion curve away from
the first plane toward the second plane.
8. The heat recovery device of claim 1, wherein the second end of
the upstream conduit portion and the first end of the downstream
conduit portion are free from connection to each other or to other
portions of the gas flow conduit.
9. The heat recovery device of claim 1, wherein the gas flow
direction at the gas inlet opening of the heat exchanger is at an
angle of about 90 degrees to the overall gas flow direction through
the gas flow conduit.
10. The heat recovery device of claim 1, wherein the gas flow
direction at the gas outlet opening of the heat exchanger is at an
angle of about 90 degrees to the overall gas flow direction through
the gas flow conduit.
11. The heat recovery device of claim 1, wherein the gas flow
direction at the second end of the upstream conduit portion and the
first end of the downstream conduit portion is at an angle of about
90 degrees to the overall gas flow direction through the gas flow
conduit.
12. The heat recovery device of claim 1, wherein the heat exchanger
is constructed from a stack of plates defining alternating gas flow
passages and liquid flow passages extending substantially parallel
to the overall gas flow direction through the gas flow conduit.
13. The heat recovery device of claim 1, wherein the heat exchanger
further comprises a gas inlet manifold communicating with the gas
inlet opening and a gas outlet manifold communicating with the gas
outlet opening, and wherein a gas flow direction through each of
the gas inlet manifold and the gas outlet manifold is at an angle
to the overall gas flow direction through the gas flow conduit.
14. The heat recovery device of claim 1, wherein the gas diverter
valve is located at the divergent branch point.
15. The heat recovery device of claim 14, wherein, with the gas
diverter valve in the bypass position, gas flow to the heat
exchange branch conduit is substantially completely blocked; and
with the gas diverter valve in the heat exchange position, gas flow
to the bypass branch conduit is substantially completely
blocked.
16. The heat recovery device of claim 1, wherein the heat exchanger
further comprises a bottom plate in which the gas inlet opening and
the gas outlet opening are provided, and wherein the second end of
the upstream conduit portion and the first end of the downstream
conduit portion are secured to the bottom plate.
17. The heat recovery device of claim 16, wherein the bottom plate
is reinforced or thickened, at least in areas proximate to the gas
inlet opening and the gas outlet opening.
18. The heat recovery device of claim 1, wherein the second end of
the upstream conduit portion and the first end of the downstream
conduit portion are aligned with one another along the overall gas
flow direction.
19. The heat recovery device of claim 1, wherein the second end of
the upstream conduit portion and the first end of the downstream
conduit portion are aligned with one another along a direction
which is substantially perpendicular to the overall gas flow
direction.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of U.S.
Provisional Patent Application No. 61/916,336 filed Dec. 16, 2013,
the contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to devices for removing heat from gas
streams, such as heat recovery devices for removing heat from motor
vehicle intake and exhaust gas systems.
BACKGROUND OF THE INVENTION
[0003] The need to remove heat from gas streams arises in numerous
applications. In motor vehicles, for instance, it may be necessary
to remove heat from the intake and/or exhaust gas streams. For
example, intake air (or "charge air") requires cooling in some
applications, for example in turbocharged or supercharged engines.
In vehicles incorporating exhaust gas recirculation (EGR) or
exhaust gas heat recovery (EGHR) systems, heat is removed from the
exhaust gas stream. The heat removed from the intake or exhaust gas
stream is typically transferred to a liquid coolant in a heat
exchanger.
[0004] In EGHR systems, for example, heat from vehicle exhaust
gases is transferred to other vehicle components via a liquid
coolant or oil in order to provide faster heating of air and
vehicle fluids on start-up of the vehicle, thereby reducing fuel
consumption. Air heated by the exhaust gases can be used for rapid
heating of the passenger compartment and for window defrosting,
reducing the need for long idling periods during start-up in cold
weather. Heat extracted from the exhaust and used to heat up
vehicle fluids such as engine oil and transmission fluid makes them
less viscous and improves fuel economy during start-up. After the
initial start-up period the recovery of heat from the exhaust gases
is no longer required. Therefore, EGHR systems typically include a
bypass to minimize heat transfer from the exhaust gases to the
liquid coolant once the vehicle reaches normal operating
temperature. This helps to minimize the load on the cooling system
and minimizes the risk of boiling or thermal degradation of the
liquid coolant.
[0005] An EGHR system therefore incorporates a gas-to-liquid heat
exchanger for extracting heat from the vehicle exhaust gas and
transferring the heat to a liquid coolant, typically a water/glycol
engine coolant, although direct heat transfer to an oil is also
possible. The EGHR system also includes a gas diverter valve for
directing at least a portion of the exhaust gas flow through the
heat exchanger during vehicle start-up, and for bypassing the heat
exchanger once the heat from the exhaust gas is no longer required.
The heat exchanger and the valve need to be connected to the
exhaust gas system piping. An actuator is also provided in order to
control operation of the valve. The valve may be operated by means
of an electronically controlled solenoid, a wax motor, engine
vacuum or a bimetal or shape memory alloy (SMA) actuator.
[0006] To save space and to reduce cost and vehicle weight, the
valve and heat exchanger may be integrated into a single unit,
referred to herein as an EGHR device. In many integrated EGHR
devices, however, the heat exchanger is heated by the exhaust gases
whether the device is in heat exchange mode or bypass mode. This
may be due to exhaust gas leakage past the valve and/or thermal
conduction. This increases the amount of heat transferred to the
coolant, increasing the load on the cooling system, and risking
cumulative thermal degradation of the coolant or induced thermal
stresses which can cause damage to the heat exchanger.
[0007] EGHR devices have been developed to address some of these
issues. For example, commonly assigned U.S. Provisional Patent
Application No. 61/771,608 filed on Mar. 1, 2013, and U.S. patent
application Ser. No. 13/599,339 filed on Aug. 30, 2012 (published
as US 2013/0061584 A1 on Mar. 14, 2013), have a substantially
T-shaped or U-shaped configuration. This configuration has a
shorter module length in the gas flow direction, which may allow it
to be located in the engine compartment, closer to the source of
the hot exhaust gas. Also, the T-shaped configuration also permits
the heat exchanger to be spaced away from the exhaust gas conduit,
reducing the amount of heat transferred from the exhaust gas to the
coolant with the device in bypass mode. However, this design
requires a separate valve body or flow duct between the exhaust gas
conduit and the heat exchanger, with a solid flange interface
between the heat exchanger and the valve body or flow duct. This
structural constraint affects the ability of the EGHR device to
expand under different operating gas temperatures and, in
particular, affects the flexibility of the heat exchanger body
between its inlet and outlet ports, which are at significantly
different temperatures. This may lead to high thermal stresses in
the heat exchanger, and potential failure of the heat exchanger
plates close to the flange interface.
[0008] Therefore, there remains a need for simple and effective
heat recovery devices for motor vehicle intake and exhaust gas
systems which minimize usage of space, weight, and number of
components, which are readily integratable into existing exhaust
system piping, and which also minimize thermal stresses and
unwanted heat transfer to the coolant in bypass mode.
SUMMARY
[0009] In an embodiment, there is provided a heat recovery device,
comprising: a gas flow conduit having an inlet and an outlet,
wherein an overall gas flow direction through the gas flow conduit
is defined between the inlet and the outlet thereof; a gas/liquid
heat exchanger having a gas inlet opening and a gas outlet opening;
a gas diverter valve provided in the gas flow conduit, wherein the
valve is movable between a bypass position and a heat exchange
position. The gas flow conduit includes a divergent branch point at
which the gas flow conduit is divided into a bypass branch conduit
and a heat exchange branch conduit. The bypass branch conduit
bypasses the heat exchanger, and the heat exchange branch conduit
includes an upstream conduit portion and a downstream conduit
portion. The upstream conduit portion has a first end in flow
communication with said gas flow conduit at said divergent branch
point, and a second end in flow communication with the gas inlet
opening of the heat exchanger. The downstream conduit portion has a
first end in flow communication with the gas outlet opening of the
heat exchanger. The gas flow direction into the gas inlet opening
of the heat exchanger diverges in a direction away from the overall
gas flow direction through the gas flow conduit.
[0010] According to one aspect, the heat recovery further comprises
a convergent branch point at which the bypass branch conduit and
the heat exchange branch conduit converge, the convergent branch
point being located upstream of the outlet of the gas flow conduit.
The downstream conduit portion may have a second end in flow
communication with the gas flow conduit at the convergent branch
point.
[0011] According to another aspect, a first plane passes through
the inlet and outlet of the gas flow conduit, the first branch
point and the bypass branch conduit. A second plane may pass
through the second end of the upstream conduit portion and the
first end of the downstream conduit portion, wherein portions of
the first and second planes passing through heat recovery device
are spaced apart from one another. The second end of the upstream
conduit portion and the first end of the downstream conduit portion
may be secured to the heat exchanger at the respective gas inlet
opening and gas outlet opening, in said second plane.
[0012] According to yet another aspect, the upstream conduit
portion and the downstream conduit portion curve away from the
first plane toward the second plane.
[0013] According to yet another aspect, the second end of the
upstream conduit portion and the first end of the downstream
conduit portion are free from connection to each other or to other
portions of the gas flow conduit.
[0014] According to yet another aspect, the gas flow direction at
the gas inlet opening of the heat exchanger is at an angle of about
90 degrees to the overall gas flow direction through the gas flow
conduit.
[0015] According to yet another aspect, the gas flow direction at
the gas outlet opening of the heat exchanger is at an angle of
about 90 degrees to the overall gas flow direction through the gas
flow conduit.
[0016] According to yet another aspect, the gas flow direction at
the second end of the upstream conduit portion and the first end of
the downstream conduit portion is at an angle of about 90 degrees
to the overall gas flow direction through the gas flow conduit.
[0017] According to yet another aspect, the heat exchanger is
constructed from a stack of plates defining alternating gas flow
passages and liquid flow passages extending substantially parallel
to the overall gas flow direction through the gas flow conduit.
[0018] According to yet another aspect, the heat exchanger further
comprises a gas inlet manifold communicating with the gas inlet
opening and a gas outlet manifold communicating with the gas outlet
opening, and wherein a gas flow direction through each of the gas
inlet manifold and the gas outlet manifold is at an angle to the
overall gas flow direction through the gas flow conduit.
[0019] According to yet another aspect, the gas diverter valve is
located at the divergent branch point. With the gas diverter valve
in the bypass position, gas flow to the heat exchange branch
conduit may be substantially completely blocked; and with the gas
diverter valve in the heat exchange position, gas flow to the
bypass branch conduit may be substantially completely blocked.
[0020] According to yet another aspect, the heat exchanger further
comprises a bottom plate in which the gas inlet opening and the gas
outlet opening are provided, and wherein the second end of the
upstream conduit portion and the first end of the downstream
conduit portion are secured to the bottom plate. The bottom plate
may be reinforced or thickened, at least in areas proximate to the
gas inlet opening and the gas outlet opening.
[0021] According to yet another aspect, the second end of the
upstream conduit portion and the first end of the downstream
conduit portion are aligned with one another along the overall gas
flow direction.
[0022] According to yet another aspect, the second end of the
upstream conduit portion and the first end of the downstream
conduit portion are aligned with one another along a direction
which is substantially perpendicular to the overall gas flow
direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The invention will now be described, by way of example only,
with reference to the accompanying drawings, in which:
[0024] FIG. 1 is a top perspective view of a heat recovery device
according to a first embodiment of the invention;
[0025] FIG. 2 is an end elevation view of the heat recovery device
of FIG. 1, taken from the inlet end thereof;
[0026] FIG. 3 is a top plan view of the heat recovery device of
FIG. 1, with the gas diverter valve in the bypass mode, and with
the gas flow conduit sectioned in first plane PL1 of FIG. 2;
[0027] FIG. 4 is a top plan view of the heat recovery device of
FIG. 1, with the gas diverter valve in the heat exchange mode, and
with the gas flow conduit sectioned in first plane PL1 of FIG.
2;
[0028] FIG. 5 is an isolated, top perspective view showing the gas
flow conduit of the heat recovery device of FIG. 1;
[0029] FIG. 6 is a perspective view of the device of FIG. 1,
showing the opposite side of the device;
[0030] FIG. 7 is a cross section along line 7-7' of FIG. 1;
[0031] FIG. 8 is a bottom perspective view of a heat recovery
device according to a second embodiment;
[0032] FIG. 9 is a top perspective view of the heat recovery device
shown in FIG. 8;
[0033] FIG. 10 is a top plan view of a heat recovery device
according to a third embodiment, partly in cross-section; and
[0034] FIG. 11 is a top perspective view of the gas flow conduit of
the heat recovery device of FIG. 10.
DETAILED DESCRIPTION
[0035] A heat recovery device 10 according to a first embodiment is
now described with reference to FIGS. 1-5. The heat recovery device
10 may be used as an EGHR device in a motor vehicle exhaust system,
and is therefore sometimes referred to herein as EGHR device
10.
[0036] The device 10 comprises a gas diverter valve 12, a
gas/liquid heat exchanger 14 and a gas flow conduit 16. The gas
flow conduit 16 has an inlet 18 and an outlet 20. Where device 10
is an EGHR device, the device 10 will be installed in an exhaust
gas conduit of a motor vehicle, downstream of the exhaust manifold
and upstream of the tail pipe. Due to its compact size, the device
10 may be located in the engine compartment of the vehicle, close
to the exhaust manifold. As used herein, the terms "upstream" and
"downstream" are terms which are used to describe the locations of
elements of the device 10, relative to the flow path of a gas
flowing through the device 10.
[0037] An overall direction of gas flow through device 10 is
defined between the inlet 18 and the outlet 20. In the present
embodiment, the overall direction of gas flow is parallel to arrows
A and B of FIG. 1, which is the same as the direction of gas flow
at the inlet 18 and outlet 20, respectively.
[0038] The heat exchanger 14 may be similar or identical to the
heat exchanger described in commonly assigned U.S. patent
application Ser. No. 13/599,399 for an invention entitled "Exhaust
Gas Heat Recovery Device", filed on Aug. 30, 2012, which is
incorporated herein by reference in its entirety.
[0039] The heat exchanger 14 comprises a heat exchanger core 22
including a stack of core plates 24 defining a plurality of gas
flow passages 26 and a plurality of liquid flow passages 28
arranged in alternating order. The gas flow passages 26 and the
liquid flow passages 28 may be parallel to the flow of gas through
the gas conduit 20. The gas flowing through the gas flow passages
26 may be a hot vehicle exhaust gas, and the liquid flowing through
the liquid flow passages 28 may be a liquid coolant, such as a
water/glycol engine coolant which may also circulate through other
components of the vehicle's cooling system. The core plates 24 may
comprise stainless steel or other heat resisting material, and may
be joined by brazing with a suitable filler metal.
[0040] A plurality of manifolds extends through the core 22, and
may be substantially perpendicular to the direction of gas flow
through conduit 20. The heat exchanger 14 includes four such
manifolds, namely a gas inlet manifold 30 and a gas outlet manifold
32 in flow communication with the gas flow passages 26; and a
liquid inlet manifold 34 and a liquid outlet manifold 36 in flow
communication with the liquid flow passages 28. The liquid
manifolds 34, 36 are in flow communication with a pair of liquid
fittings 6, 8.
[0041] The heat exchanger core 22 has a bottom plate 38 provided
with a gas inlet opening 40 and a gas outlet opening 42. The
openings 40, 42 extend through the bottom plate 38 and communicate
with the gas inlet and outlet manifolds 30, 32, respectively. The
heat exchanger 14 differs from that described in U.S. patent
application Ser. No. 13/599,399 in that it does not include a thick
mounting plate for mounting to the flange of a valve body. The
attachment of a continuous mounting plate to the bottom plate 38
could constrain the flexibility of the heat exchanger 14 between
the gas inlet and outlet openings 40, 42, and lead to high thermal
stresses in the heat exchanger.
[0042] The structure of the heat exchanger 14 is not shown in
detail in any of the drawings, except in the cross section of FIG.
7. It will be appreciated that the heat exchanger may be
"self-enclosing" as shown in FIG. 7, i.e. it does not include an
external housing. However, this is not essential, and the heat
exchanger 14 may instead include an external housing enclosing a
plurality of tubes or plates defining gas and/or liquid flow
passages.
[0043] Between its inlet 18 and outlet 20, the gas flow conduit 16
is divided into a bypass branch conduit 46 and a heat exchange
branch conduit 48. In this embodiment, the bypass branch conduit 46
extends along the overall gas flow direction. The bypass branch
conduit 46 defines a bypass gas flow path along which the gas may
flow without passing through the heat exchanger 14 under conditions
where recovery of heat from the gas is not required, such as when
the vehicle reaches its normal operating temperature.
[0044] The gas flow conduit 16 is divided into branch conduits 46,
48 at a divergent branch point 50 located upstream of the heat
exchanger 14. In this embodiment the gas diverter valve 12 is
located at the divergent branch point 50 to selectively block gas
flow to either of the branch conduits 46, 48, depending on a
position of the valve 12.
[0045] The branch conduits 46, 48 may converge downstream of heat
exchanger 14, at a convergent branch point 52 located upstream of
the outlet 20 of gas flow conduit 16.
[0046] The heat exchange branch conduit 48 comprises an upstream
conduit portion 54 and a downstream conduit portion 56. The
upstream conduit portion 50 has a first end 58 in flow
communication with the gas flow conduit 16 at the divergent branch
point 50, so as to receive the gas from the inlet 18, and a second
end 60 in flow communication with the gas inlet opening 40 of heat
exchanger 14.
[0047] The downstream conduit portion 56 has a first end 62 in flow
communication with the gas outlet opening 42 of the heat exchanger
14, and a second end 64 which may be in flow communication with the
gas flow conduit 16 at the convergent branch point 52.
[0048] It can be seen from the drawings that the direction of gas
flow at the gas inlet opening 40 and gas outlet opening 42 of heat
exchanger 14 is different from the overall gas flow direction
through the gas flow conduit 16. In this regard, the direction of
gas flow diverges from the overall gas flow direction as it flows
through the heat exchange branch conduit 48 toward the heat
exchanger 14. In the present embodiment, the direction of the gas
flow as it enters the first end 58 of the upstream conduit portion
54 is substantially the same as the overall gas flow direction. The
upstream conduit portion 54 is curved by about 90 degrees along its
length, to cause the gas flow to undergo a change in direction of
about 90 degrees relative to the overall gas flow direction, at the
second end 60 of the upstream conduit portion 54 and the gas inlet
opening 40 of the heat exchanger.
[0049] Also, it can be seen from FIG. 7 that the direction of gas
flow within the heat exchanger 14 is substantially U-shaped,
flowing through the gas inlet and outlet manifolds 30, 32 in
opposite directions which are at about 90 degrees to the overall
gas flow direction, and flowing through the gas flow passages 26 in
a direction which may be substantially parallel to the overall gas
flow direction. This U-shaped flow path through heat exchanger 14
provides device 10 with a short module length in the gas flow
direction, as in the T-shaped EGHR devices mentioned above.
[0050] At the gas outlet opening 42 of heat exchanger and the first
end 62 of the downstream conduit portion 56 the gas flow direction
is still at an angle of about 90 degrees relative to the overall
gas flow direction. The downstream conduit portion 56 is curved by
about 90 degrees along its length, to cause the gas flow to undergo
a change in direction of about 90 degrees, such that the gas flow
is substantially parallel to the overall gas flow direction by the
time it reaches the second end 64 of the downstream conduit portion
56.
[0051] Thus, it can be seen that the upstream and downstream
conduit portions 54, 56 form curved transitions to change the
direction of the gas flow entering and exiting the heat exchanger
14. This permits the use of a compact heat exchanger with a
U-shaped flow path, but also provides other advantages. It can be
seen from the drawings, and particularly from FIGS. 3 to 5, that
the second end 60 of the upstream conduit portion 54 and the first
end 62 of the downstream conduit portion 56 are free from any
connection to each other and are also free from any connection to
other portions of the gas flow conduit 16. The upstream and
downstream conduit portions 54, 56 are only connected to the
remainder of the gas flow conduit 16 at their respective opposite
ends 58, 64. Because the ends 60 and 62 of conduit portions 54, 56
are free from connection to the remainder of the gas flow conduit
16, and because the conduit portions 54, 56 are themselves curved,
they are able to flex toward and away from each other (i.e.
substantially in the overall gas flow direction) by a small amount,
thereby relieving potential thermal stresses which may be brought
about by thermal expansion and contraction of the heat exchanger 14
along the lengths of the plates 24.
[0052] It can be seen from the drawings that, with the exception of
the divergent portions of the heat exchange branch conduit 48, the
gas flow conduit 16 lies substantially in a single plane. In this
regard, the inlet 18, outlet 20, bypass branch conduit 46, the
divergent branch point 50 and the convergent branch point 52 are
all substantially coplanar, such that a first plane PL1 (FIG. 2)
may pass through some or all of these components.
[0053] The divergent portions of the heat exchange branch conduit
48, on the other hand, and particularly the upstream and downstream
conduit portions 54, 56, curve away from this first plane, and
extend toward a second plane PL2 (FIG. 2) which passes through the
second end 60 of upstream conduit portion 54 and the first end 62
of the downstream conduit portion 56, and/or the points at which
the conduit portions 54 and 56 are secured to the heat exchanger
14.
[0054] While the first and second planes need not be parallel to
one another, the portions of the planes passing through portions of
device 10 are spaced apart from one another. This spacing can be
seen, for example, in FIG. 2, and results in the heat exchanger 14
being spaced apart from portions of the gas flow conduit 16, except
of course the heat exchange branch conduit 48. Thus, with the
device 10 in bypass mode, the heat exchanger 14 is spaced from the
flow of hot gas through the bypass branch conduit 46, reducing the
amount of heat transferred from the exhaust gas to the coolant with
the device 10 in bypass mode.
[0055] The gas diverter valve 12 includes a movable valve element
82 which is pivotably mounted in the gas flow conduit 16. The valve
member 82 comprises a flapper which pivots about a pivot axis P
extending through the flow duct at an angle of about 90 degrees to
the direction of gas flow through the conduit 16. The valve member
82 may be mounted on a rod 84, and is rotated on rod 84 between the
heat exchange position (FIG. 4) and the bypass position (FIG.
3).
[0056] In the embodiments shown in the drawings, the valve element
82 is mounted at the convergent branch point 50, which enables the
valve element 82 to block the entrance to the bypass branch conduit
46 or the heat exchange branch circuit 48. While this arrangement
provides the maximum benefit in terms of isolating the heat
exchanger 14 from the flow of hot gas in the bypass mode, it will
be appreciated that the valve element 82 may be mounted elsewhere
in the gas flow conduit. For example, a similarly configured valve
element 82 could be mounted at the convergent branch point 52 to
alternately block the exits of the bypass branch conduit 46 and the
heat exchange branch conduit 48. Alternatively, the valve element
82 could be a butterfly type valve element mounted in the bypass
branch conduit, to alternately open and block the bypass gas flow
through the bypass branch conduit 46. As another alternative, the
valve element 82 could be a butterfly type valve element mounted in
the heat exchange branch conduit 48, to alternately open and block
the bypass gas flow through the heat exchange branch conduit
48.
[0057] The pivoting of valve member 82 about axis P may be
controlled by any suitable means, including an electronic solenoid
or an actuator driven by engine vacuum, or other suitable actuator
or control system. The valve member 82 and may be of any suitable
shape, so as to seal with the inner surface of the gas flow conduit
16 in the heat exchange position and the bypass position, and will
depend at least partly on the shape of the flow duct 16. To
maximize thermal isolation of the heat exchanger 14 in the bypass
mode, the valve member 82 should substantially completely block gas
flow to the heat exchange branch conduit 48 when in the bypass
position. It may also be desired to seal with the inner surface of
conduit 16 so that it will substantially completely block gas flow
to the bypass branch conduit 48 when in the heat exchange position,
although this is less critical.
[0058] Shown in the drawings is a bushing or "bearing block" 88
into which an end of the valve rod 84 extends and which may house
valve bearings (not shown). Typically one end of the valve rod will
be received in a bushing 88 which may be located within the flow
duct 16, and an opposite end of the valve rod 84 will typically
penetrate the duct wall and extend through a bushing or bearing
block 88 mounting either inside or outside the duct wall. Also, the
penetrating end of valve rod 84 will typically be attached to the
valve actuation mechanism 86, schematically shown in FIG. 5.
[0059] In operation of device 10, with the valve member 82 in the
heat exchange position shown in FIG. 4, the bypass branch conduit
46 is at least partly blocked by valve member 82 while the entrance
to the heat exchange branch conduit 48 is substantially completely
open, permitting flow through heat exchanger 14. The gas flow from
the inlet 18 enters the heat exchange branch circuit 48 at
divergent branch point 50 and enters the first end 58 of the
upstream conduit portion 54. The gas then flows through the
upstream conduit portion 54 to the second end 60 thereof, before
entering the heat exchanger 14 through the gas inlet opening 40.
Inside the heat exchanger 14, the gas flows into the gas inlet
manifold 30, from where it enters the gas flow passages 26 to
transfer heat to the liquid coolant flowing through liquid flow
passages 28. The gas then flows out from the gas flow passages 26
and into the gas outlet manifold 32, from where it exits the heat
exchanger 14 through the gas outlet opening 42. From the gas outlet
opening 42 of heat exchanger 14, the gas enters the first end of
the downstream conduit portion 56 and flows to the second end 64
thereof at the convergent branch point 52, from where it flows
toward the outlet 20.
[0060] With the valve 12 in the bypass position of FIG. 3, the gas
flow from the inlet 18 enters the bypass branch circuit 46 at the
divergent branch point 50. The gas then flows through the bypass
branch circuit 46 to the convergent branch point 52, from where it
flows toward the outlet 20.
[0061] The conduit portions 54, 56 of the heat exchange branch
circuit 48 may be secured to the heat exchanger 14 by various
means, one of which is shown in the cross-section of FIG. 7. As
shown, the second end 60 of upstream conduit portion 54 and the
first end 62 of downstream conduit portion 56 may be provided with
ridges 66 and 68, respectively, adjacent their ends, to act as
stops against over-insertion into the heat exchanger 14 through the
bottom plate 38. The ends 60, 62 may also be expanded by swaging to
achieve a tight fit within the gas inlet and outlet openings 40,
42, followed by brazing. It will be appreciated that other
arrangements exist for mounting the conduit portions 54, 56 to heat
exchanger 14. It will also be appreciated that the bottom plate 38
may be reinforced and/or thickened, at least in the areas
surrounding the gas inlet and outlet openings 40, 42, so as to
provide a strong joint between the bottom plate 38 and the conduit
portions 54, 56.
[0062] In device 10 the upstream and downstream conduit portions
54, 56 of the heat exchange branch circuit 48 are aligned with one
another along the overall gas flow direction. Also, the heat
exchange branch circuit 48 is parallel to the bypass branch circuit
46, at least in the plan view of FIGS. 3 and 4. However, the
orientation of the components relative to one another is subject to
change, depending at least partially on packaging requirements.
Therefore, the orientation of components may vary from that of
device 10, as will be discussed below with reference to FIGS. 8 to
10.
[0063] FIGS. 8 and 9 illustrate a heat recovery device 100
according to a second embodiment of the invention. The heat
recovery device 100 of FIGS. 8 and 9 differs from heat recovery
device 10 in the orientation of its components. All the elements of
device 100 are also included in device 10 and have already been
described above, and further description of these elements is
unnecessary. The elements which are shared by heat recovery devices
10 and 100 are identified by like reference numerals in FIGS. 8 and
9.
[0064] In the heat recovery device 100 of FIGS. 8 and 9, the
upstream and downstream conduit portions 54, 56 of the heat
exchange branch circuit 48 are aligned with one another along a
direction which is at about 90 degrees to the overall gas flow
direction, and at about 90 degrees to the direction of gas flow
through the bypass branch circuit 46. In addition, the direction of
gas flow through the gas flow passages 26 is oriented at an angle
of about 90 degrees to the overall gas flow direction. It will be
appreciated that the orientation of the heat exchanger 14 at 90
degrees to the overall gas flow direction is not necessary in this
embodiment. For example, the heat exchanger 14 may be oriented
diagonally to the overall gas flow direction.
[0065] It can be seen that the device 100 according to the second
embodiment considerably shortens the length of the downstream
conduit portion 56 in the heat exchange branch circuit 48,
effectively eliminating the portion of downstream conduit portion
56 which extends parallel to the bypass branch circuit 46, as the
two branch circuits 46, 48 approach the convergent branch point 52.
Thus, the device 100 may be more compact, lighter and use less
material than the device 10 described above. It will be
appreciated, however, that the overall configuration of the heat
recovery devices described herein will depend at least partially on
space restraints in the vehicles in which they are installed.
[0066] FIGS. 10 and 11 illustrate a heat recovery device 110
according to a third embodiment of the invention. The view of heat
recovery device 110 in FIG. 10 is similar to that shown in FIG. 3;
sectioned in a first horizontal plane, with the valve 12 in the
bypass position, and showing the outline of heat exchanger 14 in
dotted lines. FIG. 11 shows the gas flow conduit 16 of heat
recovery device 110 in isolation. The heat recovery device 110
differs from heat recovery devices 10 and 100 in the orientation of
its components. All the elements of device 110 are also included in
devices 10 and 100, and have already been described above, and
further description of these elements is unnecessary. The elements
which are shared by heat recovery devices 10 and 110 are identified
by like reference numerals in FIG. 10.
[0067] The heat recovery device 110 of FIGS. 10 and 11 achieves a
similar benefit as the heat recovery device 100 described above, in
that it substantially eliminates the portion of downstream conduit
portion 56 which extends parallel to the bypass branch circuit 46.
In heat recovery device 110, the rectangular openings at the second
end 60 of upstream conduit portions 54 and the first end 62 of the
downstream conduit portion 56 are aligned relative to one another
(as shown by the dotted lines in FIG. 11), but are rotated slightly
(about an axis perpendicular to the plane of the paper in FIG. 10)
relative to the overall gas flow direction, and to the gas flow
direction through the bypass branch circuit 46. This slight
rotation minimizes the length of the downstream conduit portion 56
while maintaining alignment of the rectangular openings, to
simplify the connection of the heat exchanger 14 to the conduit
portions 54 and 56. As a result, the heat exchanger 14 and the gas
flow passages 26 thereof are angled relative to the overall gas
flow direction and to the direction of gas flow through the bypass
branch conduit 46.
[0068] 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.
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