U.S. patent application number 14/190648 was filed with the patent office on 2014-09-11 for heat recovery system and heat exchanger.
This patent application is currently assigned to Wescast Industries, Inc.. The applicant listed for this patent is Wescast Industries, Inc.. Invention is credited to Clayton A. Sloss.
Application Number | 20140251579 14/190648 |
Document ID | / |
Family ID | 51486389 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140251579 |
Kind Code |
A1 |
Sloss; Clayton A. |
September 11, 2014 |
HEAT RECOVERY SYSTEM AND HEAT EXCHANGER
Abstract
An exhaust gas heat recovery system may include a housing, a
valve member, and a heat exchanger. The housing may include an
inlet, an outlet, a first exhaust gas pathway in communication with
the inlet and outlet, and a second exhaust gas pathway in
communication with the inlet and outlet. The valve member may be
disposed within the housing and may be movable between first and
second positions. In the first position, the valve member may allow
fluid flow through the first exhaust gas pathway and substantially
prevent fluid flow through the second exhaust gas pathway. In the
second position, the valve member may allow fluid flow through the
second exhaust gas pathway. The heat exchanger may be in
communication with the second exhaust gas pathway and may include a
conduit containing a fluid in thermal communication with exhaust
gas when the valve member is in the second position.
Inventors: |
Sloss; Clayton A.; (Paris,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wescast Industries, Inc. |
Brantford |
|
CA |
|
|
Assignee: |
Wescast Industries, Inc.
Brantford
CA
|
Family ID: |
51486389 |
Appl. No.: |
14/190648 |
Filed: |
February 26, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61772578 |
Mar 5, 2013 |
|
|
|
Current U.S.
Class: |
165/96 |
Current CPC
Class: |
F01N 5/02 20130101; F28D
21/0003 20130101; F28D 9/0093 20130101; Y02T 10/12 20130101; F28F
27/02 20130101; Y02T 10/16 20130101; F28D 9/0043 20130101; F01N
2240/02 20130101 |
Class at
Publication: |
165/96 |
International
Class: |
F01N 5/02 20060101
F01N005/02 |
Claims
1. A system for recovering heat from exhaust gas of an internal
combustion engine, the system comprising: a body including an
inlet, an outlet, a first exhaust gas pathway in communication with
the inlet and the outlet, and a second exhaust gas pathway in
communication with the inlet and the outlet, the body adapted to
receive exhaust gas from the internal combustion engine; a valve
member disposed within the body and movable between a first
position allowing fluid flow through the first exhaust gas pathway
and restricting fluid flow through the second exhaust gas pathway
and a second position allowing fluid flow through the second
exhaust gas pathway; and a heat exchanger in communication with the
second exhaust gas pathway and including first, second, third and
fourth cooling plates arranged parallel to each other, the first
and second cooling plates defining a first working fluid cavity
therebetween, the third and fourth cooling plates defining a second
working fluid cavity therebetween, the second and third cooling
plates defining a first exhaust passage therebetween, the first
cooling plate defining a second exhaust passage that is parallel to
the first exhaust passage, the first and second exhaust passages
are in communication with the second exhaust gas pathway.
2. The system of claim 1, wherein the heat exchanger includes a
housing in which the first, second, third and fourth cooling plates
are disposed, the housing includes a working fluid inlet and a
working fluid outlet in fluid communication with the first and
second working fluid cavities.
3. The system of claim 2, wherein the first, second, third and
fourth cooling plates are arranged parallel to a direction of fluid
flow through the first exhaust gas pathway.
4. The system of claim 3, wherein the heat exchanger includes first
and second deflector plates disposed within the housing at
respective first and second opposing edges of the first, second,
third and fourth cooling plates.
5. The system of claim 4, wherein the housing includes a proximal
end attached to the body and a distal end opposite the proximal
end, and wherein the working fluid inlet and the working fluid
outlet are disposed in respective corners of the housing at or near
the distal end.
6. The system of claim 5, wherein the first working fluid cavity
defines first and second generally U-shaped flow paths extending
from the working fluid inlet and providing working fluid to the
working fluid outlet, the first U-shaped flow path is disposed
within the second U-shaped flow path.
7. The system of claim 6, wherein the heat exchanger includes first
and second ribs defining the first generally U-shaped flow path and
defining the second generally U-shaped flow path, at least one of
the first and second ribs including leakage openings through which
working fluid leaks between the first and second generally U-shaped
flow paths.
8. The system of claim 7, wherein the first rib is generally
U-shaped and the second rib is generally straight.
9. The system of claim 6, wherein the heat exchanger includes first
and second fin packs attached to the second and third cooling
plates, respectively, and disposed in the first and second exhaust
passages, respectively.
10. The system of claim 4, wherein the housing includes a proximal
end attached to the body and a distal end opposite the proximal
end, and wherein the working fluid inlet and the working fluid
outlet are disposed along a line extending between the distal and
proximal ends and guide exhaust gas in a U-shaped path through the
heat exchanger.
11. The system of claim 10, wherein each of the first, second and
third cooling plates include a plurality of dimples protruding into
one of the first and second exhaust passages.
12. The system of claim 1, further comprising a deflector attached
to edges of the first, second, third and fourth cooling plates
adjacent the body, the deflector preventing leakage of exhaust gas
between the valve member and the edges of the first, second, third
and fourth cooling plates when the valve member is in the second
position, and wherein the valve member abuts the deflector in the
second position.
13. A system for recovering heat from exhaust gas of an internal
combustion engine, the system comprising: a body including an
inlet, an outlet, a first exhaust gas pathway in communication with
the inlet and the outlet, and a second exhaust gas pathway in
communication with the inlet and the outlet, the body adapted to
receive exhaust gas from the internal combustion engine; a valve
member disposed within the body and movable between a first
position allowing fluid flow through the first exhaust gas pathway
and restricting fluid flow through the second exhaust gas pathway
and a second position allowing fluid flow through the second
exhaust gas pathway; and a heat exchanger in communication with the
second exhaust gas pathway and including a plurality of cooling
plates arranged parallel to each other and defining an exhaust
passage and a working fluid passage, the exhaust passage defining a
generally U-shaped flow path therethrough, the working fluid
passage including first and second generally U-shaped flow paths
receiving working fluid from a working fluid inlet and providing
working fluid to a working fluid outlet, the first U-shaped flow
path is disposed within the second U-shaped flow path, wherein a
divider defines the first and second generally U-shaped flow paths
and includes leakage openings through which working fluid leaks
between the first and second generally U-shaped flow paths.
14. The system of claim 13, wherein the plurality of cooling plates
includes first, second, third and fourth cooling plates, the first
and second cooling plates defining the working fluid passage
therebetween, the third and fourth cooling plates defining another
working fluid passage therebetween, the second and third cooling
plates defining the exhaust passage therebetween, the first cooling
plate defining another exhaust passage.
15. The system of claim 14, wherein the heat exchanger includes
another divider defining the first and second generally U-shaped
flow paths and including leakage openings through which working
fluid leaks between the first and second generally U-shaped flow
paths.
16. The system of claim 15, wherein one of the dividers is
generally U-shaped and the other divider is generally straight.
17. The system of claim 13, wherein the cooling plates are arranged
parallel to a direction of fluid flow through the first exhaust gas
pathway.
18. The system of claim 13, wherein the heat exchanger includes a
housing in which the cooling plates are disposed.
19. The system of claim 18, wherein the heat exchanger includes
first and second deflector plates disposed within the housing at
respective first and second opposing edges of the cooling
plates.
20. The system of claim 19, wherein the housing includes a proximal
end attached to the body and a distal end opposite the proximal
end, and wherein the working fluid inlet and the working fluid
outlet are disposed in respective corners of the housing at or near
the distal end.
21. The system of claim 20, wherein the heat exchanger includes a
fin pack disposed between adjacent cooling plates and disposed in
the exhaust passage.
22. The system of claim 18, wherein the housing includes a proximal
end attached to the body and a distal end opposite the proximal
end, and wherein the working fluid inlet and the working fluid
outlet are disposed along a line extending between the distal and
proximal ends and guide exhaust gas in a U-shaped path through the
heat exchanger.
23. The system of claim 22, wherein at least one of the cooling
plates includes a plurality of dimples protruding into the exhaust
passage.
24. The system of claim 13, further comprising a deflector attached
to edges of the cooling plates adjacent the body, the deflector
preventing leakage of exhaust gas between the valve member and the
edges of the cooling plates when the valve member is in the second
position, and wherein the valve member abuts the deflector in the
second position.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/772,578, filed on Mar. 5, 2013. The entire
disclosure of the above application is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates to a compact heat exchanger
and a flow control assembly, and more particularly, an automotive
exhaust heat recovery system and heat exchanger.
BACKGROUND
[0003] This section provides background information related to the
present disclosure and is not necessarily prior art.
[0004] A significant amount (e.g., approximately one-third) of
energy in fuel consumed by an internal combustion engine is lost as
heat rejected through an exhaust system associated with the
internal combustion engine. It is desirable to recover this heat or
thermal energy from exhaust gas flowing through the exhaust system
for various purposes. For example, such recovered thermal energy
can be used to heat vehicle fluids to provide faster passenger
cabin warm-up and windshield defrosting. Additionally or
alternatively, the recovered thermal energy can be used to improve
fuel economy by reducing friction and viscous losses in the vehicle
lubrication systems, for example in the engine, transmission, or
transaxle, by increasing the temperature of the corresponding
lubricants in those systems.
[0005] Recovering the heat from exhaust gases can pose technical
challenges with respect to the heat recovery device, especially
with the heat exchanger. The heat recovery system must overcome
harsh operating conditions (e.g., heat, oxidation, and corrosion)
while extracting a desired amount of heat with minimal
backpressure. Additional constraints are applied to this scenario
when the requirements for compact size, light weight, and low cost
are needed for implementation into automobiles. Additionally, the
ability to have a bypass mode where the back pressure and heat
transfer are minimized may be desirable for some engine operating
conditions or vehicle applications.
SUMMARY
[0006] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0007] The present disclosure provides a heat exchanger assembly
disposed in an exhaust gas stream that may recover thermal energy
from the exhaust gas stream. The heat exchanger assembly may be
coupled with a valve element that can be controlled to regulate a
flow of exhaust gas through either or both of a heat exchanger flow
path and a bypass flow path that bypasses the heat exchanger flow
path. The valve element may be controlled by an external actuator
and may be positioned depending upon operating conditions of the
exhaust gases, working limits of the heat exchanger, and/or demand
for thermal energy recovery, for example. The heat exchanger flow
path and the bypass flow path may terminate in a common collector
which has an outlet to connect with the remainder of the exhaust
system. The assembly can be placed at any location within the
exhaust stream. Locations relatively close to the engine may have
the potential to provide the heat exchanger with the hottest
exhaust gas temperatures, which may increase an amount of thermal
energy that the assembly is able to recover. However, the higher
the exhaust gas temperature the more demanding it is for the
durability of the heat recovery system due to the increased thermal
loading.
[0008] The controllable heat recovery assembly can be used with an
internal combustion engine, such as in an automobile, for example,
or any other combustion engine. Recovered thermal energy may be
used for rapid warm-up of engine coolant to aid in faster
windshield defrosting, improved HVAC (heating, ventilation and air
conditioning) system performance for accelerated passenger cabin
warm up, and/or to improve fuel economy by reducing viscous losses
through heating of various fluid systems in the vehicle, such as
engine oil and transmission fluid, for example. Further uses of the
recovered thermal energy may include steam generation for power
generation (e.g., in Rankine cycle systems). It will be appreciated
that the heat exchangers disclosed herein could be used with
thermoelectric devices to generate electricity from the thermal
energy in the exhaust gases.
[0009] During some periods of operation of the engine, it may not
be desirable to extract energy from the exhaust system. During
these periods it may be desirable to route exhaust gases through a
bypass flow path. It may be desirable to minimize any heat transfer
from the exhaust gases to the working fluid during bypass flow
operation. During other operating conditions, when heat extraction
is desirable, some or all of the exhaust gas may be diverted
through a flow path including the heat exchanger. The routing of
exhaust gas may be controlled in such a way that it is throttled or
adjusted to a certain percentage of flow through each of the bypass
and heat exchanger flow paths. In some embodiments, a control
module may send electronic signals to an actuator driving the valve
assembly to control and adjust a position of the valve assembly
based on operating conditions and parameters of various engine and
vehicle systems and subsystems. In some embodiments, a thermally
controlled actuator may be used to control the position of the
valve assembly. Such a thermally controlled actuator could include
a wax valve, a thermostat device, and/or any other device
configured to actuate the valve assembly in response to exhaust
gases, coolant and/or any other fluid reaching one or more
predetermined thermal states.
[0010] Regulation of the exhaust flows through the bypass and heat
exchanger flow paths allows for control over the amount of heat
energy that is able to be recovered or extracted from the exhaust
gases. Heat energy recovery from the exhaust gas may be desirable
following a start-up of the engine, for example. Under cold
start-up conditions, it may be desirable to maximize heat
extraction from the exhaust gases in order to warm up the engine
coolant, to speed up windshield defrost, and/or heat-up a passenger
compartment of the vehicle, for example. Accelerated heat-up of the
engine coolant also decreases the time-averaged engine oil
viscosity, resulting in lower viscous losses in the moving parts of
the engine and reduced fuel consumption. Alternatively, under high
speed and/or high load engine operating conditions, it may be
desirable to reduce or minimize the thermal extraction from the
exhaust gases so that excessive heat does not have to be carried
and rejected by the engine/vehicle cooling system.
[0011] In some embodiments, the assembly of the present disclosure
transfers heat from exhaust gases to additional or alternative
vehicle fluids, such as lubricants for an engine, a transmission,
an axle, and/or a differential, for example, and/or any other
fluid.
[0012] Control of the heat extraction can also be employed for
other reasons in a vehicle. For example, if the heat extraction
system is located upstream of an emissions device such as a
catalytic converter or lean NOx trap, then it may be desirable to
maintain the temperature of the exhaust gases entering that
emissions device within a specific temperature range. The
temperature range may depend upon the conversion efficiency of the
emissions device and service temperature limits for long life and
durability of the device. In this type of application, it may be
desirable to reduce or prevent heat extraction from the exhaust
gases when the emissions device is below operating temperature so
that the emissions device heats up as quickly as possible to an
optimal operating temperature. Likewise, it can be desirable to
extract heat energy from the exhaust gases, even under conditions
of high engine speed and/or load, to keep the operating temperature
of an emissions device below an upper operating temperature
threshold to prevent damage and/or maintain the efficiency of the
emissions device.
[0013] In some forms, the present disclosure provides an exhaust
gas heat recovery system that may include a housing, a valve
member, and a heat exchanger. The housing may include an inlet, an
outlet, a first exhaust gas pathway in communication with the inlet
and the outlet, and a second exhaust gas pathway in communication
with the inlet and the outlet. The valve member may be disposed
within the housing and may be movable between a first position and
a second position. In the first position, the valve member may
allow fluid flow through the first exhaust gas pathway and
substantially prevent fluid flow through the second exhaust gas
pathway. In the second position, the valve member may allow fluid
flow through the second exhaust gas pathway. The heat exchanger may
be in communication with the second exhaust gas pathway and may
include a conduit having a fluid flowing therein. The fluid may be
in thermal communication with exhaust gas in the heat exchanger
when the valve member is in the second position and may be
substantially thermally isolated from the exhaust gas when the
valve member is in the first position. The heat exchanger may be
substantially fluidly isolated from the first exhaust gas pathway
when the valve member is in the first portion.
[0014] In other forms, the present disclosure provides an exhaust
gas heat recovery system that may include a housing, a valve
member, and a heat exchanger. The housing may include an inlet, an
outlet, a first exhaust gas pathway in communication with the inlet
and the outlet, and a second exhaust gas pathway in communication
with the inlet and the outlet. The valve member may be disposed
within the housing and may be movable between a first position
allowing fluid flow through the first exhaust gas pathway and a
second position allowing fluid flow through the second exhaust gas
pathway. The heat exchanger may be in communication with the second
exhaust gas pathway and may include a conduit having a fluid
flowing therein. The fluid may be in thermal communication with
exhaust gas in the heat exchanger when the valve member is in the
second position. The housing may include a first stop member
contacting a leading end of the valve member when the valve member
is in the first position and a second stop member contacting a
trailing end of the valve member when the valve member is in the
first position. The leading end may contact a surface of the first
stop member that faces generally away from the first exhaust gas
pathway.
[0015] In some embodiments, the first exhaust gas pathway is
substantially aligned with the inlet and the outlet to define a
substantially linear flow path therethrough. In some embodiments,
the valve member at least partially defines a substantially
U-shaped flow path through the heat exchanger when the valve member
is in the second position, the valve member defining an inlet into
the U-shaped flow path and an outlet out of the U-shaped flow path
when the valve member is in the second position.
[0016] The present disclosure also provides a heat exchanger that
operates within such a heat recovery system. The heat exchanger may
utilize a U-shaped flow path through which the exhaust gases may
flow when the heat recovery system is operating in a heat recovery
mode. The construction of the heat exchanger is designed to provide
good durability under severe thermal operating conditions while
still providing good performance for heat transfer at low pressure
drop. In some embodiments, parallel cooling plates of the heat
exchanger are arranged in a manner that is perpendicular to an axis
about which a rotary valve member rotates. Heat transfer fins may
be arranged between the cooling plates to increase heat transfer
from the exhaust gases. Cooling plate coolant headers may be
located in opposite corners of the heat exchanger along an edge of
the cooling plates distal to the valve body. Features may be
provided in the cooling plates to uniformly distribute coolant
throughout the cooling cavity.
[0017] In some embodiments, the heat exchanger is configured for
high temperature applications. In such embodiments, cooling plates
may be arranged perpendicular to the rotary valve member axis, and
one or more surfaces of the cooling plates are textured with heat
transfer enhancing geometric features. The coolant headers in these
embodiments may be located on or near a centerline of the cooling
plates, adjacent to each other and proximate to the valve body to
form a distinct U-shaped flow path through which the exhaust gases
flow. Features may be provided in the cooling plates to uniformly
distribute coolant throughout the cooling cavity.
[0018] In some embodiments, a cooling plate arrangement is provided
whereby the cooling plates are parallel to the valve plate when the
valve plate is in the bypass position. In such embodiments the
cooling plates may be contained in an outer shell which may also
form the exhaust gas headers on both the inlet and outlet sides of
the gas pathway through the heat exchanger.
[0019] In some embodiments, the exhaust gas heat recovery system
heats two fluid streams from the exhaust gas. In some embodiments,
an exhaust gas recirculation (EGR) cooler is combined and/or
operate in concert with an exhaust gas heat recovery (EGHR) system.
In some embodiments, the exhaust gas heat recovery system includes
a gas to gas heat exchanger arrangement.
[0020] In some embodiments, an inlet and an outlet of the valve
body may be in communication with an exhaust manifold associated
with an engine and substantially all of the exhaust gas that flows
through the exhaust manifold may flow through the inlet and the
outlet.
[0021] In another form, the present disclosure provides another
system for recovering heat from exhaust gas of an internal
combustion engine. The system may include a body, a valve member
and a heat exchanger. The body may include an inlet, an outlet, a
first exhaust gas pathway in communication with the inlet and the
outlet, and a second exhaust gas pathway in communication with the
inlet and the outlet. The body may be adapted to receive exhaust
gas from the internal combustion engine. The valve member may be
disposed within the body and may be movable between a first
position allowing fluid flow through the first exhaust gas pathway
and restricting fluid flow through the second exhaust gas pathway
and a second position allowing fluid flow through the second
exhaust gas pathway. The heat exchanger may be in communication
with the second exhaust gas pathway and may include first, second,
third and fourth cooling plates arranged parallel to each other.
The first and second cooling plates may define a first working
fluid cavity therebetween. The third and fourth cooling plates may
define a second working fluid cavity therebetween. The second and
third cooling plates may define a first exhaust passage
therebetween. The first cooling plate may define a second exhaust
passage that is parallel to the first exhaust passage. The first
and second exhaust passages may be in communication with the second
exhaust gas pathway.
[0022] In some embodiments, the heat exchanger includes a housing
in which the first, second, third and fourth cooling plates are
disposed. The housing may include a working fluid inlet and a
working fluid outlet in fluid communication with the first and
second working fluid cavities.
[0023] In some embodiments, the first, second, third and fourth
cooling plates are arranged parallel to a direction of fluid flow
through the first exhaust gas pathway.
[0024] In some embodiments, the heat exchanger includes first and
second deflector plates disposed within the housing at respective
first and second opposing edges of the first, second, third and
fourth cooling plates.
[0025] In some embodiments, the housing includes a proximal end
attached to the body and a distal end opposite the proximal end.
The working fluid inlet and the working fluid outlet may be
disposed in respective corners of the housing at or near the distal
end.
[0026] In some embodiments, the first working fluid cavity defines
first and second generally U-shaped flow paths extending from the
working fluid inlet and providing working fluid to the working
fluid outlet, the first U-shaped flow path is disposed within the
second U-shaped flow path.
[0027] In some embodiments, the heat exchanger includes first and
second ribs defining the first generally U-shaped flow path and
defining the second generally U-shaped flow path. At least one of
the first and second ribs may include leakage openings through
which working fluid leaks between the first and second generally
U-shaped flow paths.
[0028] In some embodiments, the first rib is generally U-shaped and
the second rib is generally straight.
[0029] In some embodiments, the heat exchanger includes first and
second fin packs attached to the second and third cooling plates,
respectively, and disposed in the first and second exhaust
passages, respectively.
[0030] In some embodiments, the housing includes a proximal end
attached to the body and a distal end opposite the proximal end.
The working fluid inlet and the working fluid outlet may be
disposed along a line extending between the distal and proximal
ends and guide exhaust gas in a U-shaped path through the heat
exchanger.
[0031] In some embodiments, each of the first, second and third
cooling plates include a plurality of dimples protruding into one
of the first and second exhaust passages.
[0032] In some embodiments, the system includes a deflector
attached to edges of the first, second, third and fourth cooling
plates adjacent the body. The deflector may prevent leakage of
exhaust gas between the valve member and the edges of the first,
second, third and fourth cooling plates when the valve member is in
the second position. The valve member may abut the deflector in the
second position.
[0033] In some embodiments, the heat exchanger includes a deflector
plate and a housing in which the cooling plates are disposed. The
deflector plate may be disposed within the housing and may include
a plurality of slots receiving the cooling plates. Each of the
slots may be defined by a corresponding pair of resiliently
flexible tabs that grip edges of the cooling plates.
[0034] In some embodiments, the tabs may be arranged to increase a
grip on the edges of the cooling plates in response to movement of
the deflector plate relative to the cooling plates.
[0035] In another form, the present disclosure provides another
system for recovering heat from exhaust gas of an internal
combustion engine. The system may include a body, a valve member
and a heat exchanger. The body may include an inlet, an outlet, a
first exhaust gas pathway in communication with the inlet and the
outlet, and a second exhaust gas pathway in communication with the
inlet and the outlet. The body may be adapted to receive exhaust
gas from the internal combustion engine. The valve member may be
disposed within the body and movable between a first position
allowing fluid flow through the first exhaust gas pathway and
restricting fluid flow through the second exhaust gas pathway and a
second position allowing fluid flow through the second exhaust gas
pathway. The heat exchanger may be in communication with the second
exhaust gas pathway and may include a plurality of cooling plates
arranged parallel to each other and defining an exhaust passage and
a working fluid passage. The exhaust passage may define a generally
U-shaped flow path therethrough. The working fluid passage may
include first and second generally U-shaped flow paths receiving
working fluid from a working fluid inlet and providing working
fluid to a working fluid outlet. The first U-shaped flow path may
be disposed within the second U-shaped flow path. A divider may
define the first and second generally U-shaped flow paths and may
include leakage openings through which working fluid leaks between
the first and second generally U-shaped flow paths.
[0036] In some embodiments, the plurality of cooling plates
includes first, second, third and fourth cooling plates. The first
and second cooling plates may define the working fluid passage
therebetween. The third and fourth cooling plates may define
another working fluid passage therebetween. The second and third
cooling plates may define the exhaust passage therebetween. The
first cooling plate may define another exhaust passage.
[0037] In some embodiments, the heat exchanger includes another
divider that defines the first and second generally U-shaped flow
paths and includes leakage openings through which working fluid
leaks between the first and second generally U-shaped flow
paths.
[0038] In some embodiments, one of the dividers is generally
U-shaped and the other divider is generally straight.
[0039] In some embodiments, the cooling plates are arranged
parallel to a direction of fluid flow through the first exhaust gas
pathway.
[0040] In some embodiments, the heat exchanger includes a housing
in which the cooling plates are disposed.
[0041] In some embodiments, the heat exchanger includes first and
second deflector plates disposed within the housing at respective
first and second opposing edges of the cooling plates.
[0042] In some embodiments, the housing includes a proximal end
attached to the body and a distal end opposite the proximal end.
The working fluid inlet and the working fluid outlet may be
disposed in respective corners of the housing at or near the distal
end.
[0043] In some embodiments, the heat exchanger includes a fin pack
disposed between adjacent cooling plates and disposed in the
exhaust passage.
[0044] In some embodiments, the housing includes a proximal end
attached to the body and a distal end opposite the proximal end.
The working fluid inlet and the working fluid outlet may be
disposed along a line extending between the distal and proximal
ends and guide exhaust gas in a U-shaped path through the heat
exchanger.
[0045] In some embodiments, at least one of the cooling plates
includes a plurality of dimples protruding into the exhaust
passage.
[0046] In some embodiments, the system includes a deflector
attached to edges of the cooling plates adjacent the body. The
deflector may prevent leakage of exhaust gas between the valve
member and the edges of the cooling plates when the valve member is
in the second position. The valve member may abut the deflector in
the second position.
[0047] In some embodiments, the heat exchanger includes a deflector
plate and a housing in which the cooling plates are disposed. The
deflector plate may be disposed within the housing and may include
a plurality of slots receiving the cooling plates. Each of the
slots may be defined by a corresponding pair of resiliently
flexible tabs that grip edges of the cooling plates.
[0048] In some embodiments, the tabs may be arranged to increase a
grip on the edges of the cooling plates in response to movement of
the deflector plate relative to the cooling plates.
[0049] In another form, the present disclosure provides another
system for recovering heat from exhaust gas of an internal
combustion engine. The system may include first and second valve
assemblies and a heat exchanger. The first valve assembly may
include a first valve body and a first valve member. The first
valve body may include a first inlet, a first outlet and a first
opening. The first inlet may be configured to receive exhaust gas
from the internal combustion engine. The first valve member may be
disposed within the first valve body and may be movable relative
thereto between a first bypass position and a first heat exchange
position. The first valve member restricts fluid communication
between the first inlet and the first opening in the first bypass
position and allows fluid communication among the first inlet, the
first opening and the first outlet in the first heat exchange
position. The second valve assembly may include a second valve body
and a second valve member. The second valve body may include a
second inlet, a second outlet and a second opening. The second
inlet may be configured to receive a fluid from a fluid source. The
second valve member may be disposed within the second valve body
and may be movable relative thereto between a second bypass
position and a second heat exchange position. The second valve
member restricts fluid communication between the second inlet and
the second opening in the second bypass position and allows fluid
communication among the second inlet, the second opening and the
second outlet in the second heat exchange position. The heat
exchanger may be attached to and disposed between the first and
second valve bodies and may include an exhaust gas passageway and a
fluid passageway. The exhaust gas passageway may be in fluid
communication with the first opening and may receive exhaust gas
from the first inlet when the first valve member is in the first
heat exchange position. The fluid passageway may be in fluid
communication with the second opening and may receive fluid from
the second inlet when the second valve member is in the second heat
exchange position. The fluid passageway may be fluidly isolated
from the exhaust gas passageway and may be in a heat transfer
relationship with the exhaust gas passageway.
[0050] In some embodiments, the heat exchanger includes first and
second plates and first and second fin packs. The second fin pack
may be disposed between the first and second plates.
[0051] In some embodiments, the first plate and the first fin pack
may define a first portion of the exhaust gas passageway. The first
plate and the second fin pack may define a first portion of the
fluid passageway. The second fin pack and the second plate may
define a second portion of the exhaust gas passageway.
[0052] In some embodiments, the heat exchanger includes an outer
housing encasing the first and second plates and the first and
second fin packs. The first and second valve bodies may be attached
to opposing first and second ends of the outer housing.
[0053] In some embodiments, the first valve assembly and the heat
exchanger cooperate to define a first U-shaped flow path. The
second valve assembly and the heat exchanger may cooperate to
define a second U-shaped flow path.
[0054] In some embodiments, the first and second U-shaped flow
paths are misaligned with each other by one-hundred-eighty
degrees.
[0055] In some embodiments, the fluid is air and the fluid source
is an HVAC duct.
[0056] In some embodiments, the fluid is air and the fluid source
is an air-induction duct supplying air to the engine.
[0057] In another form, the present disclosure provides another
system for recovering heat from exhaust gas of an internal
combustion engine. The system may include a valve assembly and a
heat exchanger. The valve assembly may include a valve body and a
valve member. The valve body may include an inlet, an outlet and an
opening. The inlet may be configured to receive exhaust gas from
the internal combustion engine. The valve member may be disposed
within the valve body and movable relative thereto between a bypass
position and a heat exchange position. The valve member restricts
fluid communication between the inlet and the opening in the bypass
position and allows fluid communication among the inlet, the
opening and the outlet in the heat exchange position. The heat
exchanger may be attached to the valve body and may include an
exhaust gas passageway, a first fluid passageway and a second fluid
passageway. The first and second fluid passageways may be fluidly
isolated from each other and from the exhaust gas passageway. The
exhaust gas passageway may be in heat transfer relationships with
the first and second fluid passageways.
[0058] In another form, the present disclosure provides another
system for recovering heat from exhaust gas of an internal
combustion engine. The system may include a valve assembly and a
heat exchanger. The valve assembly may include a valve body and
first and second valve members. The valve body may include an
inlet, an outlet, a first volume, a second volume, a first opening
and a second opening. The inlet may be configured to receive
exhaust gas from the internal combustion engine and supply the
exhaust gas to the first and second volumes. The first valve member
may be disposed within the first volume and may be movable relative
thereto between a first bypass position and a first heat exchange
position. The first valve member restricts fluid communication
between the first volume and the first opening in the first bypass
position and allows fluid communication among the inlet, the first
volume, the first opening and the outlet in the first heat exchange
position. The second valve member may be disposed within the second
volume and may be movable relative thereto independently of the
first valve member between a second bypass position and a second
heat exchange position. The second valve member restricts fluid
communication between the second volume and the second opening in
the second bypass position and allows fluid communication among the
inlet, the second volume, the second opening and the outlet in the
second heat exchange position. The heat exchanger may be attached
to the valve body and may include first and second exhaust gas
passageways and first and second fluid passageways. The first and
second fluid passageways may be fluidly isolated from each other
and from the first and second exhaust gas passageways. The first
and second exhaust gas passageways may be in heat transfer
relationships with the first and second fluid passageways,
respectively. The first and second exhaust gas passageways may be
substantially thermally isolated from the second and first fluid
passageways, respectively.
[0059] In some embodiments, the valve body includes an interior
dividing wall that separates the first and second volumes.
[0060] In another form, the present disclosure provides another
system for recovering heat from exhaust gas of an internal
combustion engine. The system may include a valve assembly and a
heat exchanger. The valve assembly may include a valve body and a
valve member. The valve body may include an inlet, an outlet and an
opening. The inlet may be configured to receive exhaust gas from
the internal combustion engine. The valve member may be disposed
within the valve body and may be movable relative thereto between a
bypass position and a heat exchange position. The valve member
restricts fluid communication between the inlet and the opening in
the bypass position and allows fluid communication among the inlet,
the opening and the outlet in the heat exchange position. The heat
exchanger may be attached to the valve body and may include an
exhaust gas passageway and a fluid passageway. The fluid passageway
may be fluidly isolated from the exhaust gas passageway. The
exhaust gas passageway may be in a heat transfer relationship with
the fluid passageway. The exhaust gas passageway may include an
inlet and first and second outlets. The inlet may receive exhaust
gas from the opening in the valve body. The first outlet may
provide exhaust gas to the outlet of the valve body. The second
outlet may provide exhaust gas to an exhaust gas recirculation
conduit.
[0061] In some embodiments, the first outlet of the heat exchanger
is disposed at a first end of the heat exchanger and the second
outlet of the heat exchanger is disposed at a second end of the
heat exchanger opposite the first end.
[0062] In some embodiments, the exhaust gas recirculation conduit
includes a valve movable between a first position allowing exhaust
gas from the exhaust gas passageway to exit the heat exchanger
through the second outlet and a second position restricting exhaust
gas from the exhaust gas passageway from exiting the heat exchanger
through the second outlet.
[0063] In some embodiments, the exhaust gas recirculation conduit
provides exhaust gas to an induction system of the engine.
[0064] In another form, the present disclosure provides another
system for recovering heat from exhaust gas of an internal
combustion engine. The system may include a valve assembly and a
heat exchanger. The valve assembly may include a valve body and a
valve member. The valve body may include an inlet, an outlet and an
opening. The inlet may be configured to receive exhaust gas from
the internal combustion engine. The valve member may be disposed
within the valve body and movable relative thereto between a bypass
position and a heat exchange position. The valve member restricts
fluid communication between the inlet and the opening in the bypass
position and allows fluid communication among the inlet, the
opening and the outlet in the heat exchange position. The heat
exchanger may be attached to the valve body and may include cooling
plates defining an exhaust gas passageway and a fluid passageway.
The fluid passageway may be fluidly isolated from the exhaust gas
passageway. The exhaust gas passageway may be in a heat transfer
relationship with the fluid passageway. The heat exchanger may also
include a deflector plate and a housing in which the cooling plates
are disposed. The deflector plate may be disposed within the
housing and may include a plurality of slots receiving the cooling
plates. Each of the slots may be defined by a corresponding pair of
resiliently flexible tabs that grip edges of the cooling
plates.
[0065] In some embodiments, the tabs are arranged to increase a
grip on the edges of the cooling plates in response to movement of
the deflector plate relative to the cooling plates.
[0066] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0067] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0068] FIG. 1 is a schematic representation of an engine and
exhaust system having an exhaust gas heat recovery system according
to the principles of the present disclosure;
[0069] FIG. 2 is a perspective view of an exhaust gas heat recovery
system according to the principles of the present disclosure;
[0070] FIG. 3 is a perspective, partially cross-sectioned view of
the exhaust gas heat recovery system of FIG. 2 with a heat
exchanger core that is decoupled from the heat exchanger cover
plates;
[0071] FIG. 4 is a cross-sectional view of the exhaust heat
recovery system of FIG. 2 including a valve element shown in a heat
exchange position;
[0072] FIG. 4a is a cross-sectional view of the exhaust heat
recovery system of FIG. 2 including the valve element in a bypass
position;
[0073] FIG. 5 is a partial perspective view of a fin pack of the
exhaust gas heat recovery system of FIG. 4;
[0074] FIG. 6 is a perspective view of a side deflector plate of
the exhaust gas heat recovery system of FIGS. 3 and 4;
[0075] FIG. 6b is a partial cross-sectional view of the side
deflector plate engaging cooling plates of a heat exchanger;
[0076] FIG. 7a is a front view of a cooling plate with a fin
pack;
[0077] FIG. 7b is an end view of an offset strip fin pack coupled
with cooling plates;
[0078] FIG. 7c is an end view of decoupled saw-tooth fin packs
joined to cooling plates;
[0079] FIG. 7d is an end view of a single decoupled saw-tooth fin
pack joined to a single cooling plate;
[0080] FIG. 8 is a front view of the interior of a coolant cavity
to illustrate the flow and distribution of coolant within a coolant
cavity;
[0081] FIG. 9 is a clipped perspective view of a heat exchanger
core to illustrate the flow of coolant into the heat exchanger,
distributed to each of the coolant cavities, and finally out of the
heat exchanger;
[0082] FIG. 10 is a clipped perspective view of a heat exchanger
core that is coupled with the heat exchanger cover plates;
[0083] FIG. 11 is a perspective view of another exhaust gas heat
recovery system wherein the heat exchanger has coolant inlet and
outlet tubes near the centerline of the heat exchanger;
[0084] FIG. 12 is a perspective partially cross-sectioned view of
the exhaust gas heat recovery system of FIG. 11 with a heat
exchanger core that is coupled to the heat exchanger cover
plates;
[0085] FIG. 13 is a perspective view of a top deflector plate that
can be incorporated into either of the exhaust gas heat recovery
systems of FIGS. 12 and 3;
[0086] FIG. 14 is a cross-sectional view of the exhaust heat
recovery system of FIG. 11 including a valve element shown in a
heat exchange position;
[0087] FIG. 14a is a partial cross-sectional view of the exhaust
gas heat recovery system of FIG. 14;
[0088] FIG. 15 is a front view of the interior of a coolant cavity
of the embodiment in FIG. 12 to illustrate the flow and
distribution of coolant within a coolant cavity;
[0089] FIG. 15a is a cross-sectional view taken along line A-B of
FIG. 15;
[0090] FIG. 15b is a cross-sectional view taken along line C-D of
FIG. 15;
[0091] FIG. 16 is a clipped perspective view of an alternative heat
exchanger core that is decoupled from the heat exchanger cover
plates to illustrate the flow of coolant into the heat exchanger,
distributed to each of the coolant cavities, and finally out of the
heat exchanger;
[0092] FIG. 17 is a front view of an alternative cooling plate for
the heat exchanger core for the embodiment shown in FIG. 12;
[0093] FIG. 17a is a cross-sectional view taken along line A-A of
FIG. 17;
[0094] FIG. 18 is a schematic representation of a dual working
fluid heat exchanger for an EGHR system;
[0095] FIG. 19 is a partially cross-sectioned perspective view of
the dual working fluid heat exchanger EGHR system of FIG. 18;
[0096] FIG. 20 is a partially cross-sectioned perspective view of
another dual working fluid heat exchanger EGHR system;
[0097] FIG. 21 is a schematic representation of a combined EGHR-EGR
system whereby a single heat exchanger can be used for both EGR
cooling and exhaust gas heat recovery to transfer heat to other
fluid systems in a vehicle;
[0098] FIG. 22 is a partially cross-sectioned perspective view of
the combined EGHR-EGR system of FIG. 21, with a closed EGR valve
position;
[0099] FIG. 23 is a cross-sectional perspective view of the
combined EGHR-EGR embodiment of FIG. 22, shown with an open EGR
valve position;
[0100] FIG. 24 is a cross-sectional view of another combined
EGHR-EGR system including an EGR valve in the closed position;
[0101] FIG. 25 is a schematic representation of another EGHR system
that can transfer heat from the engine exhaust system to a second
gaseous fluid;
[0102] FIG. 26 is a schematic representation of another EGHR system
that can transfer heat from the engine exhaust system to the intake
air of the same engine system;
[0103] FIG. 27 is a perspective cross-sectional view of an
air-to-air heat exchanger EGHR system that can be incorporated into
either of the systems shown in FIGS. 25 and 26;
[0104] FIG. 27a is a perspective cross-sectional view of the heat
exchanger core of an air-to-air heat exchanger;
[0105] FIG. 27b is a perspective view of a heat exchanger plate of
the type described for use in an air-to-air heat exchanger
core;
[0106] FIG. 27c is a close-up, perspective partial view of the heat
exchanger plate of FIG. 27b;
[0107] FIG. 27d is an end view of the heat exchanger for an
air-to-air heat exchanger;
[0108] FIG. 27e is a close-up partial view of the heat exchanger in
FIG. 27d;
[0109] FIG. 27f is a cross-section through an air-to-air heat
exchanger, corresponding to section A-A of FIG. 27d;
[0110] FIG. 27g is a close-up partial view of the heat exchanger
view in FIG. 27f;
[0111] FIG. 28 is a perspective view of another heat exchanger and
valve body for an EGHR system;
[0112] FIG. 29 is a perspective view illustrating a heat exchanger
core and heat exchanger housing for the EGHR system of FIG. 28;
[0113] FIG. 30 is a perspective view illustrating side deflector
plates and cooling plate geometry of the heat exchanger of the EGHR
system of FIG. 28; and
[0114] FIG. 31 is a cross-sectional view of the EGHR system of FIG.
28 depicting coolant headers and illustrating a manner in which
coolant inlet and outlet tubes from the heat exchanger cooperate
with coolant conduits in the valve body.
DETAILED DESCRIPTION
[0115] Example embodiments will now be described more fully with
reference to the accompanying drawings. It should be understood
that throughout the drawings, corresponding reference numerals
indicate like or corresponding parts and features. The following
description is merely exemplary in nature and is not intended to
limit the present disclosure, application, or uses.
[0116] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific components, and devices, to provide a thorough
understanding of embodiments of the present disclosure. It will be
apparent to those skilled in the art that specific details need not
be employed, that example embodiments may be embodied in many
different forms and that neither should be construed to limit the
scope of the disclosure. In some example embodiments, well-known
processes, well-known device structures, and well-known
technologies are not described in detail.
[0117] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an" and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0118] When an element or layer is referred to as being "on,"
"engaged to," "connected to" or "coupled to" another element or
layer, it may be directly on, engaged, connected or coupled to the
other element or layer, or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," "directly engaged to," "directly connected to" or
"directly coupled to" another element or layer, there may be no
intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0119] Although the terms first, second, third, etc. may be used
herein to describe various elements, components, regions, layers
and/or sections, these elements, components, regions, layers and/or
sections should not be limited by these terms. These terms may be
only used to distinguish one element, component, region, layer or
section from another region, layer or section. Terms such as
"first," "second," and other numerical terms when used herein do
not imply a sequence or order unless clearly indicated by the
context. Thus, a first element, component, region, layer or section
discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of
the example embodiments.
[0120] Spatially relative terms, such as "inner," "outer,"
"beneath," "below," "lower," "above," "upper" and the like, may be
used herein for ease of description to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Spatially relative terms may be
intended to encompass different orientations of the device in use
or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an
orientation of above and below. The device may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein interpreted
accordingly.
[0121] With reference to FIGS. 1-10, an exhaust gas heat recovery
system (EGHR system) 10 is provided and may include a valve
assembly 16 and a heat exchanger assembly 17. The EGHR system 10
may be disposed in an exhaust gas flow path of an engine exhaust
system 15 at any suitable location between the cylinder head 14
associated with an engine 11 and a tailpipe through which exhaust
gas is discharged into ambient air. In some embodiments, the EGHR
system 10 may be in direct or indirect fluid communication with a
catalytic converter, a NO.sub.x trap, an exhaust manifold, or
turbocharger for example, or any other exhaust system component.
The EGHR system 10 may be disposed in a tunnel or channel (not
shown) in the underside of a vehicle where the exhaust system 15
may be routed, or closer to the engine 11 in an engine compartment
of a vehicle. In some embodiments, the EGHR system 10 may receive
substantially all of the exhaust gas discharged from the engine 11
and the cylinder head 14. In other embodiments, an exhaust gas
recirculation (EGR) device may be disposed between the engine 11
and the EGHR system 10. In such embodiments, the EGHR system 10 may
receive substantially all of the exhaust gas that is not
recirculated from the EGR device back to the engine intake charge
air system 12 and/or intake air pipe 13. In some embodiments, the
EGR device may be disposed downstream of the EGHR system 10. Heat
that is recovered from the exhaust gases by the heat exchanger
assembly 17 may be transferred to a working fluid, such as an
engine coolant, an engine oil, or a transmission oil, for example,
or any other lubricant or other fluid in the vehicle. When heat is
transferred to the working fluid, the temperature of the working
fluid exiting the heat exchanger 17 through an outlet 58 is warmer
than the temperature of the working fluid entering the heat
exchanger 17 through an inlet 57.
[0122] The valve assembly 16 may be of one of the types disclosed
in Assignee's commonly owned United States Patent Application
Publication No. 2012/0017575, the disclosure of which is hereby
incorporated by reference in its entirety. As will be subsequently
described, a valve plate 80 of the valve assembly 16 may be movable
between a bypass position (FIG. 4a) and a heat-exchange position
(FIGS. 3 and 4). In the heat-exchange position, exhaust gas may
flow through the heat exchanger assembly 17 and transfer heat to
the working fluid. In the bypass position, the exhaust gas may
bypass the heat exchanger assembly 17 and exit the EGHR system 10
through an outlet collector 59 without transferring heat (or any
significant amount of heat) between the exhaust gas and the heat
exchanger assembly 17. While not specifically shown, the valve
plate 80 can be positioned anywhere between the bypass position and
the heat-exchange position to allow a first portion of the exhaust
gas entering the EGHR system 10 to bypass the heat exchanger
assembly 17 and a second portion of the exhaust gas to flow through
the heat exchanger assembly 17. In this manner, the EGHR system 10
can adjust and optimize an amount of heat transfer between the
exhaust gas and the fluid in the heat exchanger assembly 17.
[0123] The valve assembly 16 may include a valve body 50, a main
valve shaft 54, and the valve plate or diverter plate 80. The valve
body 50 may house the main valve shaft 54 and diverter plate 80 and
may be shaped so as to control and regulate the exhaust gas flow
through the valve body 50 and heat exchange flow paths. The valve
body 50 may include an inlet 51, an outlet 59, and one or more
openings for fluid communication with the heat exchanger assembly
17.
[0124] The valve assembly 16 may be attached to the exhaust system
by an inlet flange 52 and an outlet flange 53. The connection with
the exhaust system may be by bolted flange, welded connection, or
otherwise coupled. Similarly, the valve assembly 16 may be attached
to the heat exchanger assembly 17 by welded interface (shown) or
otherwise bolted or coupled, with or without a gasket. In this
embodiment, the valve body 50 has a flange 55 for coupling with the
heat exchanger assembly 17. The welded coupling provides the
advantage of a leak-free seal, while the gasketed version of the
coupling helps to reduce conductive heat transfer, especially if
the gasket contains an insulating material. Coolant enters the heat
exchanger assembly 17 through a working fluid inlet tube 57 and
exits through a working fluid exit tube 58. In some operating
environments it may be desirable to reverse the flow of working
fluid through the heat exchanger assembly, depending on the
construction of the heat exchanger assembly and the desired
operating conditions of the heat exchanger (parallel flow or
counter flow operation).
[0125] The position of the valve plate 80 may regulate exhaust gas
flow through the EGHR system 10 downstream of the valve body inlet
51. The valve plate 80 may be a "butterfly" type (e.g., extending
in both directions from axis of the main valve shaft 54) but the
valve plate 80 may also be a "flap" type, extending in only one
direction from the axis of the main valve shaft 54. The valve plate
80 is may be supported by a main shaft 54 on one side and a stub
shaft 85 on the other. The valve plate 80 may also be cantilevered
from a single end, the main valve shaft 54. The main valve shaft 54
and stub shaft 85 are supported by a bushing 81 or bearing surface,
in cooperation with the valve housing 50. The choice of bushing
and/or bearing material may depend on the application temperature
and the material of the valve shaft(s) and valve body 50. An
actuator (not shown) may rotate the main valve shaft 54 to move the
valve plate 80 between the bypass and heat-exchange positions.
Motion of the actuator may be controlled by a control module and
may transferred to the main valve shaft 54 by means of an actuator
arm, linkage, or any other suitable mechanism (not shown). The main
valve shaft 54 is externally retained in axial position by a
retaining washer 56.
[0126] During operation of the EGHR system 10, the exhaust gases
enter into the valve body 50 and are directed into the bypass
conduit and/or the heat exchanger assembly 17, depending on the
position of the valve plate 80. Valve plate stop or seat features
87 may be formed into the valve body 50 to reduce or prevent
unwanted leakage between the valve body 50 and the valve plate 80
when the valve plate 80 is in the heat-exchange position. The seat
feature 87 for the valve plate 80 also provides a positive stop to
limit the rotation of the valve plate 80 about the axis of the main
valve shaft 54. This may allow some embodiments to employ a simple
actuator without position control (or without fine position
control). For example, in applications that do not require
modulation of the position of the valve plate 80, a low-cost
two-position actuator may be used.
[0127] The heat exchanger assembly 17 may include a plurality of
coolant plates 100 that are perpendicular to a rotational axis of
the main valve shaft 54 and substantially parallel to the bypass
flow path between the valve body inlet 51 and the valve body outlet
59. This configuration may help to minimize back pressure through
the EGHR system 10 when operating in heat exchange mode. A heat
exchanger core may include a stack of interior cooling plates 100,
along with a heat exchanger front coolant plate 95 and a heat
exchanger back coolant plate. The front coolant plate 95 and the
back coolant plate may or may not be identical to the interior
cooling plates 100. The cooling plates are arranged such that there
is a coolant cavity 104 (FIG. 3) between the cooling plates. The
working fluid is circulated in this cavity 104 between the cooling
plates. Exhaust gas is circulated outside of the cooling plate
cavities and heat transfer occurs between the exhaust gas and the
working fluid. The working fluid cavity 104 is sealed from direct
contact with the exhaust gas. The working fluid cavity 104 from one
cooling plate pair is fluidly connected to the working fluid cavity
104 in an adjacent cooling plate pair through a working fluid inlet
header 124 and a working fluid outlet header 125. The working fluid
inlet header 124 is connected to the working fluid supply via the
coolant inlet tube 57, and similarly, the working fluid outlet
header is connected to the working fluid return system via the
coolant outlet tube 58. The cooling plate subassembly or heat
exchanger core is contained within a heat exchanger housing 91. The
heat exchanger housing 91 may include a series of cover plates that
form a sealed enclosure for the cooling plate subassembly when
coupled with the valve body 50. Specifically, the heat exchanger
housing 91 may include a front cover plate 98, a back cover plate
97, and a side cover plate 96. In the embodiment shown, the heat
exchanger housing 91 is welded to valve body flange 55.
[0128] In one embodiment of the heat exchanger assembly 17, the
first cooling cavity 104 may be formed between the front coolant
plate 95 and the adjacent interior cooling plate 100. Similarly,
the last cooling cavity in the heat exchanger core is formed
between the back coolant plate and its adjacent interior cooling
plate 100. The sub-assembly of cooling plates is held within the
heat exchanger housing 91 by welded or brazed coupling around the
cooling inlet and outlet tubes, 57 and 58, respectively, and at
other coupling zones 105 where the front cover plate 98 is coupled
with the front cooling plate 95 and similarly the back cover plate
is coupled with the back cooling plate. The placement of the
coupling zones 105 are selected to be in relatively cooler areas of
the heat exchanger and located to allow differential movement
between the heat exchanger core and the front and rear cover plates
without inducing stresses between the heat exchanger housing and
the heat exchanger core. This method of having selective coupling
between the heat exchanger housing and the front and back cooling
plates was found to have the least thermal durability issues when
fin packs 83 are used in the exhaust gas passageways between the
cooling plates to enhance heat transfer from the exhaust gases.
[0129] A side deflector plate 99 is used on both sides of the heat
exchanger between the heat exchanger side cover plate 96 and the
cooling plates 100, primarily in the region adjacent to the fin
packs 83. The function of the side deflector plate 99 is to prevent
exhaust gases from bypassing the fin packs 83 by filling in the
spaces between the edges of the cooling plates 100, and between the
edge of the fin pack 83 and the side cover plate 96. The side
deflector plates 99 can also serve to locate and hold the cooling
plates 100 together during the manufacturing process. A top
deflector plate 82 is used on the top side of the cooling plates
100 between the heat exchanger and the valve assembly 16. The top
deflector plate 82 prevents unwanted exhaust gas leakage along the
top edge of the cooling plates 100 and also provides a stop and
sealing surface for the valve plate 80 when in the heat exchange
position.
[0130] Joining of all the components in the assembly can be
achieved either through laser welding, brazing, or a combination of
these two methods. It is conceivable that the components could also
be joined through any other combination of processes such as
soldering, other welding methods, gluing, and similar.
[0131] The exhaust gas flow path 132 through the EGHR system (in
the heat exchange mode) is illustrated in FIG. 4. The exhaust gases
enter the valve body inlet 51 and with the valve plate 80 in the
heat exchange position, the exhaust gases are directed to the first
portion of the heat exchanger core where the fin pack 83 is
located. The exhaust gases then travel in the exhaust gas
passageways between the coolant plate pairs. Upon exiting the first
portion of the heat exchanger fin pack 83, the exhaust gases change
direction in a generally U-shaped flow path in the second portion
of the heat exchanger core. The exhaust gases then enter the third
portion of the heat exchanger core which contains the second
portion of the fin pack 83. After the exhaust gases exit the heat
exchanger core they enter a second portion of the valve body 50
(i.e., downstream of the valve plate 80) and exit out the valve
body outlet 59. The working fluid or coolant is distributed between
the cooling plate pairs and within the cooling plate pairs via the
coolant inlet header 124 and the coolant outlet header 125. The
cooling plates are sealed together along their perimeter in an edge
coupling land 134. The pairs of cooling plates are sealed together
at the header coupling land 133 to form the coolant distribution
header.
[0132] Ideally, the fin packs 83 are located in place during
assembly with at least one locator protrusion 121 in the cooling
plates 100. The locator protrusion 121 extends outward from the
cooling cavity into the exhaust gas passageway between the cooling
plate pairs. The entire second portion of the heat exchanger
cooling plates may or may not be covered with heat transfer
enhancing geometric features 135 to increase heat transfer in the
regions of the cooling plates not directly adjacent to the fin
packs 83. The fin packs 83 can be made of a variety of heat
transfer surfaces such as lanced offset strip fin packs (FIG. 5)
and louvered fin packs (not shown). These two types of fin packs
may provide a large amount of heat transfer with minimal exhaust
gas pressure drop. The purpose of the fins is to increase the heat
transfer surface area for the exhaust gases to transfer heat to the
fins, and the fins in turn conduct the heat to the cooling plates
and ultimately to the working fluid. The height of the fin packs 83
must correspond closely with the distance between cooling plate
pairs (the gap that forms the exhaust gas passageway) to ensure
good contact between the cooling plates 100 and the fin packs 83 to
provide for good brazing conditions and/or good heat transfer.
[0133] The side deflector plates 99 are used to prevent exhaust
gases from bypassing the fin packs 83. The side deflector plates 99
(FIG. 6) have slots 151 that receive edges of the cooling plates
100 and effectively seal the gap between the edge of the fin pack
83 and the heat exchanger side cover plate 99. The side deflector
plates 99 also have a corner notch 152 to provide a good fit around
the side cover plate 96 and the front and back cover plates. The
side deflector plates 99 space the cooling plates 100 at regular
intervals (FIGS. 3 and 6b). The side deflector plates 99 are formed
in the stamping process such that the slots 151 are defined by
spring-like tabs 101 that slide over and grasp the edges of the
cooling plates 100 to firmly hold the cooling plates 100 in
place.
[0134] As shown in FIG. 6b, when the side deflector plate 99 is
engaged with the cooling plates 100, first and second tabs 101 of
each pair of adjacent tabs 101 that cooperate to define each slot
151 are angled such that the first and second tabs 101 extend
toward each other as they extend outward from a main body 103 of
the side deflector plate 99. When the cooling plates 100 are
received in the slots 151, the tabs 101 of each adjacent pair of
tabs 101 are spring biased toward each other (i.e., the resilient
flexibility of the tabs 101 urges the tabs 101 toward each other in
a manner that constricts the slots 151). This configuration of the
adjacent tabs 101 causes the tabs 101 to grip the edges of the
cooling plates 100 even tighter with any movement of the side
deflector plate 99 relative to the cooling plate 100 in the
direction (i.e., upward relative to the frame of reference of FIG.
6b) that the side deflector plate 99 must move in order to remove
the side deflector plate 99 from the cooling plate 100. Therefore,
once the side deflector plates 99 are assembled onto the cooling
plates 100, the side deflector plates 99 are very difficult to
remove because of the retaining force of the tabs 101 that grip the
cooling plates 100 with increased force as forces to remove the
side deflector plates 99 increase.
[0135] In FIGS. 7a through 7d, it can be seen how the cooling
plates 100 cooperate to form a coolant channel. The cooling plates
100 are sealed around their perimeter at the edge coupling land 134
to form cooling plate pairs. The cooling plate pairs are joined
around the coolant inlet header 124 and the coolant outlet header
125 at the header coupling land 133. The fin packs 83 are located
between the plate pairs. The fin packs 83 can traverse the entire
gap between the cooling plates 100 as in FIG. 7b. This may be
referred to as a coupled fin pack, because each fin pack 83 is in
thermal contact with two cooling plates 100 in different cooling
plate pairs. With coupled fin packs, it is may be desirable to
ensure good thermal contact between the cooling plates 100 and the
fin packs 83 by brazing the fin packs 83 to the cooling plates
100.
[0136] An alternative fin structure, such as that shown in FIG. 7c
is a decoupled fin pack. In this embodiment, each cooling plate 100
is in thermal contact with a single fin pack 83. When assembled in
the heat exchanger core, the decoupled fin packs operate much like
the coupled fin packs for heat transfer. The potential advantage of
decoupled fin packs is that they can be welded, brazed, or
otherwise joined to the cooling plates 100 in a separate
manufacturing operation prior to the assembly of the heat exchange
core. This is desirable in the case of welding the entire heat
exchanger, without the need for brazing in the manufacturing
process. For clarity, FIG. 7d illustrates the decoupled nature of a
single cooling plate 100 attached to a fin pack 83. When the
cooling plates with attached fins of FIG. 7d are assembled
together, the heat exchanger core of FIG. 7c is formed. Note also
in FIGS. 7a-7d the cooling plate ribs or diverter features 117. The
cooling plate diverter features 117 adjacent to each other in a
coolant plate pair cooperate with each other to control and direct
the flow path of the working fluid or coolant within the cooling
cavities.
[0137] The flow path of the working fluid or coolant through the
cooling cavity between cooling plates 100 is shown in FIG. 8.
Coolant entering the cooling cavity from the coolant inlet header
124 is split into two coolant flow paths: a first outer U-shaped
flow path 150a along the three perimeter edges of the coolant
cavity (i.e., outside of the U-shaped diverter features 117); and a
second, interior U-shaped flow path 150b between the diverter
feature 117 and generally linear diverter features 118. Coolant
from both flow paths is collected at the coolant outlet header
opening 125. The specific size and placement of the diverter
feature 117 and the diverter feature 118 have been calculated using
computational fluid dynamics simulation software. These features
were chosen to provide a uniform distribution of coolant across the
entire cooling plate 100 surface. In some areas the diverter
features 117, 118 on mating cooling plates cooperate to prevent
coolant flow between the diverter features 117, 118. In other
areas, the diverter features on mating cooling plates allow a
controlled amount of coolant redistribution flow 151 between or
across them. This controlled redistribution flow 151 across the
diverter features prevents regions of recirculation and stagnation
in the coolant cavity, especially on the downstream side of the
diverter features 117 and 118. For clarity, FIG. 8 depicts the
distribution and flow path of coolant within a cooling cavity
between two cooling plates 100 of a cooling plate pair, whereas
FIG. 9 illustrates the distribution of coolant throughout the
cooling plate pairs of the entire heat exchanger core. Furthermore,
FIG. 9 helps to explain the coolant or working fluid inlet flow 160
and outlet flow 161, as well as in the outer U flow path 150a. In
this view the front cooling plate 95 can be seen to form one side
of the first cooling cavity 166 and the back cooling plate 165 can
be seen to form one side of the last cooling cavity 167.
[0138] FIG. 10 represents an additional embodiment of the heat
exchanger assembly 17 of FIG. 1. In this case the first coolant
plate 170 is fully coupled with the front cover plate 180 of the
heat exchanger, and the last coolant plate 171 is fully coupled
with the back cover plate 181 of the heat exchanger. In other
words, a coolant cavity is formed between each of the front and
back cover plates and the adjacent interior cooling plates 100. To
be explicit, the first coolant cavity 183 is formed between the
front cover plate 180 and the first interior coolant plate 170, and
the last coolant cavity 184 is formed between the back cover plate
181 and the last interior coolant plate 171. The side cover plate
194 couples with the front cover plate 180 and the back cover plate
181 to enclose the heat exchanger core and contain the exhaust
gases within the heat exchanger. A U-shaped diverter rib 182 and a
linear diverter rib 193 are also formed in both the front cover
plate 180 and the back cover plate 181. Although this embodiment
may have advantages in terms of weight and cost for a given heat
exchanger core volume, the thermally induced strains may be higher
than the decoupled core design of FIG. 3 for some applications.
[0139] The areas where the coolant diverter features from one
cooling plate touch the coolant diverter features on its mating
cooling plate serve to reinforce the structure of the heat
exchanger core and prevent collapsing of the cooling cavity in the
event of an overpressure situation on the exhaust gas side or an
under-pressure situation on the cooling cavity side. Similarly,
features such as the coolant header lands 133, the fin packs 83,
and the fin pack locator protrusions 121 may cooperate between
cooling plate pairs to prevent the cooling plates 100 from buckling
due to situations where the coolant pressure is higher than the
exhaust gas pressure.
[0140] Another series of heat exchanger embodiments for an EGHR
system are disclosed in FIGS. 11-17. In the embodiment of the heat
exchanger assembly 17 depicted in FIG. 11 the coolant inlet tube
310 and coolant outlet tube 311 and coolant headers are at the
centerline of the heat exchanger. The coolant inlet header is
proximate the valve body assembly 16 to direct the coolest working
fluid to the regions of the heat exchanger coolant cavities which
experience contact with the hottest exhaust gases as they enter the
heat exchanger core. The heat exchanger front cover plate 307 and
back cover plate attach to the side cover plate 308. The front
cover plate 307 may also have relief features 312 to accommodate
cooling plate features. The features of the present valve body
assembly 16 are similar to those of the valve body assembly of FIG.
3, and like features are not described again.
[0141] In the heat exchanger 17 embodiment shown in FIG. 12, there
are no fin packs between the cooling plate pairs. Instead, the
cooling plates have a series of geometric features that work to
enhance heat transfer when compared to a flat cooling plate. In the
first finless heat exchanger embodiment, it was found that a dimple
319 height of approximately 1 mm and a dimple diameter of
approximately 2 mm gave good heat transfer with modest backpressure
while still being easily stamped into a cooling plate 306 during
the manufacturing process. Compared to the heat exchanger
identified by the embodiment shown in FIG. 3, the present
embodiment has an extra pair of cooling plates 303 added to make up
for the lower heat transfer to a single cooling plate without a fin
pack compared to a finned heat transfer surface. As well, the
general spacing between cooling plates 303 for the exhaust gas
passageway was reduced from approximately 5 mm for a finned heat
exchanger to approximately 4 mm between cooling plates 303 for the
finless heat exchanger of the present embodiment. Cooling plates
303 are may be 0.5 mm thick and the cover plates (front cover plate
307, side cover plate 308, and back cover plate 321) may be
approximately 1 mm thick. There is a tradeoff between pressure drop
and heat transfer when designing the cooling cavity separation
distance. The cooling plate cavity height is nominally between
approximately 2 and 3 mm. If the cooling cavities have too much
distance between cooling plates 303, the coolant velocity is
lowered and pressure drop is reduced, but heat transfer is
adversely affected. The heat exchanger of FIG. 3 utilizes fin packs
made from approximately 0.25 to 0.4 mm thickness. The heat
exchanger materials may be stainless steel or any other material
suitable for providing good durability and long life in the exhaust
environment which can have high temperatures and rapid temperature
changes as well as requirements to resist oxidation and corrosion.
For example, 304L stainless steel can be used for many
applications, and grades of 309 and 319 stainless steel can be
considered for more severe applications.
[0142] FIG. 12 also depicts an embodiment for the finless heat
exchanger in which the front cover plate 307 is directly sealed
with the first (or front) coolant plate 306 to form the first
coolant cavity. This coupled nature of the cover plate and the
adjacent cooling plate was found to have the lowest thermal
stresses and therefore have the best thermal durability for the
finless heat exchanger. The front and back cover plates 307, 321,
may include the coolant diversion ribs 312 stamped therein to
cooperate with the adjacent cooling plate coolant diversion ribs
320 that they are coupled with in order to control the distribution
of coolant within the coolant cavity. Coolant enters the heat
exchanger assembly 17 through the coolant inlet tube 310 and is
distributed to each cooling cavity via the coolant inlet header
309. Coolant from each cooling cavity is collected in the coolant
outlet header 305 and the coolant exits the heat exchanger assembly
through the coolant outlet tube 311.
[0143] The interior cooling plates 303 are located during assembly
with the side deflector plates 318. The side deflector plates 318
prevent the exhaust gases from bypassing the heat transfer surfaces
by filling in the gap around the cooling plate 303 edges near the
side cover plate 308. As seen in FIG. 14, side deflector plates can
be used on all three sides of the cooling plates 303 that are
adjacent to the side cover plate 308.
[0144] The top deflector plate 317 performs the same function in
the present embodiment as the embodiment shown in FIG. 3. FIG. 13
better illustrates the notches 314 that fit over the edges of the
coolant plates 303 to block the flow of exhaust gases from short
circuiting the heat exchanger from valve assembly inlet to outlet
without passing through the heat exchanger. The top deflector plate
317 may also include side blocker tabs 304 to cooperate with the
valve plate 80 to block the flow of exhaust gas in the region near
the front and rear cover plates, between the valve body and the top
edges of the cooling plates 303.
[0145] In FIG. 14 it can be seen that the central location for the
coolant tubes and headers makes for a natural U-shaped flow path
for the exhaust gases through the heat exchanger in heat exchange
operating mode. The inlet exhaust gas flow path 350 begins with
exhaust gas transferred from an upstream exhaust component to
exhaust inlet tube 363. In heat exchange mode, the exhaust gases
enter a first portion of the valve assembly 16 then turn along the
valve plate 80 to enter the heat exchanger. The exhaust gases make
one continuous U-turn through the heat exchanger core and exit the
heat exchanger into the second portion of the valve assembly 16.
The exhaust gas flow path then leaves the valve assembly and the
exhaust gases enter the next downstream exhaust component or
exhaust outlet tube 364. FIG. 14 also illustrates how three side
deflector plates 318 can be used to keep the exhaust gases within
the main heat transfer surfaces between cooling plates 303 and
prevent the gases from circulating in the regions at the cooling
plate edges between cooling plate pairs and the side cover plate
308. It should be noted that the side deflector plates 318 of FIG.
14 are similar to the side deflector plate shown in FIG. 6, except
that the notch spacing is adjusted accordingly for the specific
cooling plate 303 spacing. FIG. 14 also shows the relationship
between the valve plate 80, the top deflector plate 317, and the
cooling plates 303.
[0146] In FIG. 14 it can be seen that stand-off features 371 are
provided at various locations of the cooling plates to provide a
positive separating distance between the cooling plates 303. Also,
the plate pairs are sealed at the cooling plate inlet header land
398 and the outlet header land 399. These features hold the plate
pairs a fixed distance apart during manufacturing and help to keep
the cooling plates from bowing when the pressure on one side of a
cooling plate 303 is different from the pressure on the other side
of the cooling plate 303. A unique requirement of this embodiment
with the inlet coolant header 309 directly adjacent to the outlet
coolant header 305 is the need to put a gas flow blocker plug 372
between the coolant inlet header 309 and the coolant outlet header
305. The gas flow blocker plug 372 fills the open gas volume
created between the coolant headers due to manufacturing
constraints and prevents short circuiting of the exhaust gases
through the heat exchanger. The heat transfer enhancement features
319 on the cooling plates 303 are arranged everywhere on the
cooling plates possible to maximize heat transfer. Areas of the
cooling plates 303 that cannot easily incorporate enhanced heat
transfer features 319 include the stand-off features 371, coolant
inlet header 309, inlet header land 398, coolant outlet header 305,
outlet header land 399, and the coolant diversion ribs 320.
[0147] An additional feature which may be found on any of the heat
exchanger embodiments disclosed here is the internal heat shield
372 as detailed in FIG. 14a. This heat shield 372 is a heat
resistant material that is attached along one edge to the heat
exchanger cover plates, near the interface between the heat
exchanger and the valve body. The heat shield limits the heat
transfer from the exhaust gases to the first and last coolant
plates, thereby reducing the thermal strains that develop in the
first and last coolant plates and the front and back cover plates.
The heat shield 372 is not attached to any cooling plate so it is
free to expand without undue influence on the cooling plates. Note
that the cooling cavity 333 incorporates the back cover plate 321
which helps to cool the back cover plate and improve the durability
of the assembly. The heat shield provides a similar function for
the front cover plate 307 and the first cooling plate 306, although
not shown. Also detailed in FIG. 14a is the coupling of the valve
body flange 55 with the back cover plate 321. In this embodiment,
the cover plates are coupled to the valve body flange 55 with a
weld 377.
[0148] The placement of the coolant inlet and outlet headers
adjacent to each other on the centerline of the cooling plate also
poses an interesting problem in how to evenly distribute the
coolant over the nearly rectangular cooling plate 303 surface. A
symmetric system of coolant diversion ribs 320 was developed
through a series of computational fluid dynamics simulations as
shown in FIG. 15. Typically, the coolant inlet header 309 is placed
at the top of the heat exchanger cooling plate 303, nearest the
valve plate. This ensures that the coolest working fluid or coolant
is in contact with the cooling plates along the edge where the
exhaust gases first encounter the heat exchanger core. This aids in
keeping the heat exchanger cooling plates cool in the zone of
highest exhaust gas temperature, minimizes thermal distortion, and
extends durability. The coolant diversion ribs 320 were designed
with varying height to aid in the even distribution of coolant in
the cooling cavities. FIGS. 15a and 15b show section views through
four cooling plates 303 of the heat exchanger core, the middle two
cooling plates 303 forming a cooling cavity 345. As seen in FIGS.
15-15b, the varying height of the coolant diversion ribs
effectively blocks and permits controlled amounts of coolant flow
in certain regions to redirect the coolant and prevent regions of
stagnation and recirculation. This is also illustrated by the
general coolant flow path 391 patterns on the coolant plate 303.
The coolant diverter ribs 320 allow no leakage coolant paths in the
areas of the initial flow straighteners 393 or the coolant header
separator stand-off 394. The flow straighteners 393, coolant header
separator stand-off 394, and lower cooling plate stand-offs 392 all
serve to maintain the cooling cavity at the desired cooling cavity
height, even when the cooling plates 303 have a differential
pressure between their gas and coolant sides. The cooling plate
sealing land 390 is coupled between adjacent cooling plates 303 of
a plate pair by welding or brazing to form the peripheral seal for
the cooling cavity.
[0149] One key feature of all of the heat exchanger embodiments
disclosed in FIGS. 1-17 is that substantially all of the cooling
plate surfaces are in contact with the working fluid. Minimizing
the un-cooled portions of the cooling plates helps to improve
overall durability of the assembled plates and entire heat
exchanger.
[0150] FIG. 16 discloses another embodiment of the heat exchanger.
In this embodiment, the cooling plate pairs are mostly decoupled
from the heat exchanger front cover plate 359 and the back cover
plate 358. In other words, there is not a cooling cavity formed
between the front or back heat exchanger cover plates and the
adjacent cooling plate. The only places the first and last coolant
plates are coupled with the front and back cover plates are at the
coolant header recess 344 of the cover plates and at the stand-off
coupler recess 376 of the coupler plate.
[0151] FIG. 16 also depicts the general distribution of coolant
entering through the coolant inlet tube 310, the flow path of the
coolant 391 amongst the cooling cavities of the heat exchanger
core, and finally the coolant exiting through the coolant outlet
tube 311. The heat exchanger top deflector plate 317 and side
deflector plate 318 are also shown. The top deflector plate 317 and
side deflector plate 318 are modified as required for this
embodiment based on the particular spacing of the cooling plates
303. The notches in the heat exchanger top deflector plate 317
allow it to fit around and between the cooling plate edges to
prevent unwanted leakage of exhaust gas between the cooling plate
edges when the valve plate is in full heat exchange position. The
heat exchanger top deflector plate 317 also provides a positive
stop location for the valve plate in full heat exchange
position.
[0152] FIG. 17 discloses yet another embodiment for the cooling
plates 303 of the heat exchanger assembly. In this embodiment, a
series of ripples or ridges 381 in a herringbone pattern are formed
to enhance heat transfer between the exhaust gases in the exhaust
gas passageway 388 and the working fluid in the cooling cavity 389.
The ripple pattern can be designed to help redistribute the flow of
exhaust gases 380 to help negate the misdistribution that occurs
due to inertial forces on the exhaust gases as they travel from the
valve body through the U-shaped flow path of the heat exchanger,
while also inducing higher heat transfer than would be otherwise
encountered with a generally flat cooling plate. Such an
alternative cooling plate embodiment utilizes similar coolant
diverter ribs 320 as shown in the previous embodiment.
[0153] The embodiments disclosed in FIGS. 11-17 could be modified
to use industry standard fin packs like that shown in FIG. 5 in
cooperation with cooling plates with flat sections for coupling
with said fin packs. Similarly, any of the embodiments in FIGS.
2-10 could be utilized without the fin packs, with or without
additional heat transfer geometrical surface enhancements. In each
of the embodiments shown for a heat exchanger, it should be noted
that the first and last coolant plates may or may not be identical
to all of the other interior cooling plates.
[0154] The schematic shown in FIG. 18 is a variation of the EGHR
system in which two working fluids are used in separate coolant
circuits of the EGHR heat exchanger. In some applications, it is
desirable to heat two fluids simultaneously instead of heating one
working fluid and in turn heating the second working fluid with the
first working fluid in a serial manner. An example of this serial
heating of working fluids is using the EGHR to transfer heat to the
engine coolant, and then using the heated engine coolant to heat
the transmission oil. The problem with serial heating of working
fluids is that it takes substantially longer to heat the second
working fluid than with direct working fluid heating. For maximum
fuel economy benefit, it is advantageous to heat the transmission
oil at the same time as the engine coolant to provide faster warm
up and obtain maximum reduction of viscous friction losses.
[0155] FIG. 18 illustrates a dual working fluid EGHR system that is
attached to an engine system similar to FIG. 1. However, in the
schematic of FIG. 18, the heat exchanger assembly 25 contains a
first working fluid conduit 24 with a first working fluid inlet 18
and a first working fluid outlet 19, and a second, separate fluid
conduit 20 in the heat exchanger assembly 25 with a working fluid
inlet 21 and working fluid outlet 22 for the second working fluid.
Like numbered items are the same as in the description of FIG. 1
and are not necessarily repeated here.
[0156] FIG. 19 discloses an EGHR embodiment according to the
principles illustrated in FIG. 18. The present embodiment includes
a valve assembly 400 and a heat exchanger assembly 402. The valve
assembly 400 contains a valve body 401 with a single valve plate
420 for control of the exhaust gases through the exhaust gas
portion of the heat exchanger for both working fluids. Also note
the valve body reinforcement rib 421 that spans the valve from
front to back to reduce the thermal expansion of the valve body 401
and lessen the thermal stresses on the heat exchanger assembly 402.
The valve body reinforcement rib 421 aligns with the top deflector
plate 417 to help provide a stop for the valve plate 420 and block
the exhaust gas short circuit path when the valve plate 420 is in
full heat exchange position as shown. This valve body reinforcement
rib 421 could be included in any of the valve body embodiments
disclosed herein.
[0157] In the heat exchanger assembly 402 of FIG. 19, there is a
front cover plate 407a with a coolant inlet tube 410 and outlet
tube 411 for the first working fluid, and a second front cover
plate 407b with a coolant inlet tube and coolant outlet tube 412 on
the opposite side of the heat exchanger for the second working
fluid. Also, at least one of cooling plates 423 does not have a
through hole in the coolant inlet and outlet header. This plate(s)
423 without coolant inlet and outlet header holes effectively
separates the first working fluid from the second working fluid. As
well, the position of the plate(s) 423 without coolant inlet and
outlet header holes in the heat exchanger core determines the
relative amount of heat transfer that will be available to each
working fluid. For example, if the plate(s) 423 without coolant
inlet and outlet header holes is in the middle of the heat
exchanger core then each working fluid will receive approximately
the same amount of heat from the exhaust gases when the valve
assembly is in heat exchange mode. However, if the plate(s) 423
without coolant inlet and outlet header holes is between the third
and fourth coolant plate pairs of a nine plate pair heat exchanger,
then one working fluid will receive approximately one third of the
heat from the exhaust gases and the other fluid will receive
approximately two thirds of the heat from the exhaust gases. One
issue with this design of dual working fluid EGHR is that there is
only one valve system 400 to control the heat transfer to two
working fluids. In this case, if one working fluid is at a
condition that it cannot accept more heat input the valve system
must go into bypass mode, even if the other working fluid requires
more thermal input from the exhaust gases.
[0158] A solution to control the heat transfer to each of the
working fluids in a two working fluid EGHR system is shown in FIG.
20. In this embodiment, the inlet exhaust gases 449 can be
independently controlled to both portions of the heat exchanger
assembly 402 with first and second valve plates 425, 426,
respectively. This way each working fluid can be heated at an
independent time and rate, depending on operating conditions and
requirements. In FIG. 20, the valve body assembly 444 is shown in
the operating mode where the first exhaust gas flow path 431 is
completely bypassing the heat exchanger first portion associated
with the first working fluid (first valve plate 425 is in the
bypass position), and the second exhaust gas flow path 432 is fully
engaging the heat exchanger second portion with the second working
fluid (second valve plate 426 is in the full heat exchange
position). Two control mechanisms (actuators, mechanical couplings
or linkages, sensors, and control logic systems) are required for
this embodiment to independently control the heat transfer to each
of the working fluids.
[0159] The valve body assembly of FIG. 20 is the same in principle
as the valve bodies described above, except the valve body has an
interior dividing wall 443 that houses at least one bushing and two
stub shafts 442. Note that with this arrangement, two valve plates
425 and 426 are provided along with two main shafts 441.
[0160] FIG. 21 discloses an embodiment where the EGHR system also
provides the function of an EGR cooler. Since space in a vehicle is
limited, it would be desirable to utilize the EGHR heat exchanger
as an EGR cooler as required to avoid separate EGHR and EGR heat
exchangers. In this embodiment, exhaust gases leaving the engine
through the exhaust system pass into the EGHR system 10. When
cooled EGR gas is needed by the engine 11 to feed back into the
intake charge air system 12, a separate EGR valve 24 would open to
provide cooled exhaust gases through the EGR gas circuit 25. The
portion of exhaust gases not entering the EGR gas circuit 25 would
be discharged from the EGHR system 10 into the remainder of the
exhaust system 15. Description of the other components not
mentioned here can be found in the description of like numbered
components for the schematic of FIG. 1.
[0161] An example of an integrated EGHR-EGR system is shown in FIG.
22. The EGHR valve assembly 500 is mated to an EGHR heat exchanger
assembly 501. The EGHR heat exchanger assembly 501 can be similar
to any of the embodiments disclosed herein, with a modification to
the side cover plate 510 to make provision for attaching to the EGR
valve assembly and EGR conduit 534. In this view the butterfly
style EGR valve plate 533 is shown in the closed position,
preventing the flow of exhaust gases 545 into the EGR circuit. The
EGR valve plate is mounted on a shaft 508 and its position is
controlled by a lever arm 532 that is moved by an actuator (not
shown).
[0162] FIG. 23 is a section of the same EGHR-EGR system of FIG. 22,
only in this view the EGR butterfly valve 533 is shown in the fully
open position and exhaust gases 543 are flowing through the EGR
conduit 534. As seen in FIG. 23, when the EGHR valve plate 520 is
in the heat exchange mode and the EGR valve 533 is open, there is a
split in the flow of inlet exhaust gas 540 between the EGR circuit
flow 543 and the EGHR outlet gas flow 545. As EGR flows are
typically less than one quarter of the entire exhaust gas flow, the
EGR valve plate 533 and conduit 534 sizing is much smaller than the
EGHR control valve plate 520 size. The EGR valve system, comprised
of an EGR valve plate 533, EGR bushings 531, EGR valve shaft 508,
and EGR control arm 532, requires a complete control system
(including actuator, motor, or similar) with an integrated control
logic that would cooperate with the control system of the EGHR
valve to function properly.
[0163] FIG. 24 is an alternative EGHR-EGR system embodiment wherein
the EGR control valve 550 is of the poppet valve style and is
integrated into the EGR conduit 534. The actuation system for the
EGR valve is not shown. In FIG. 24 the EGR valve is shown in the
closed position.
[0164] An air-to-air heat exchange schematic is shown in FIG. 25.
In this case, the exhaust flow from the engine system 11 passes
through the EGHR system 600. In the EGHR heat exchanger 601, heat
is transferred from the exhaust gases to a second gas media. The
second gas media also has a gas control valve assembly 26 that
selectively passes the second gas media through the heat exchanger
601 or bypasses the heat exchanger 601 when low pressure drop
and/or no additional heat transfer is desired. An example of a
second gas media would be the cabin air heating circuit 27 of a
vehicle for rapid warm up of the passenger compartment. Since the
second gas media is fluidly isolated from the exhaust gases, there
would be no contamination of the second gas media by the exhaust
gases.
[0165] FIG. 26 shows another use of the air-to-air EGHR system. In
this case, the air-to-air EGHR system 610 is used to heat or
control the temperature of the air in the charge air intake system
12. The exhaust gases from the engine system 11 pass through the
exhaust component or conduit 15 to the exhaust gas control valve
assembly 16 before exiting the EGHR system to the remainder of the
exhaust system. When low engine exhaust back pressure or low heat
transfer from the exhaust gases is required, the exhaust gas
control valve system 16 moves into bypass position. Similarly, when
low engine intake pressure drop or low heat transfer to the intake
gases is required, the intake gas control valve 29 moves into
bypass position. To achieve maximum heat transfer from the exhaust
gases, both the exhaust gas control valve 16 and the intake air
control valve 29 would be rotated into the full heat exchange
position. It would be possible to also modulate the position of
either or both gas control valves to an intermediate position when
partial heat transfer is desired. Description of the other
components not mentioned here for FIGS. 25 and 26 can be found in
the description of like numbered components for the schematic of
FIG. 1.
[0166] The physical embodiment of the air-to-air EGHR system can be
seen in FIG. 27 and FIGS. 27a through 27f. In this cross-section of
the disclosure, the first gas control valve plate 602 is in the
heat exchange position. The flow of the first gas 603 (e.g. exhaust
gas) enters the first gas control valve assembly 650 and turns to
enter the first portion of the first gas fluid circuit of the EGHR
heat exchanger 652. The first gas then exits the first fin pack
portion 609 and enters a first fluid volume 610 between the first
and second portions of the first fin pack 609. In the volume 610
between fin pack portions the exhaust gases make a general U-turn
to enter the second portion of the first fin pack. After travelling
through the second portion of the first fluid fin pack 609, the
exhaust gases enter the second portion of the first valve body
assembly 650 and exit through the gas outlet portion 604 of the
first valve body. Similarly, when the second gas control valve
plate 618 is in the heat exchange position, the flow of the second
gas 615 (e.g. intake air) enters the second gas control valve
assembly 651 and turns to enter the first portion of the second gas
fluid circuit of the EGHR heat exchanger. The second gas then
travels through the first portion of the second fluid fin pack 607
and enters a second fluid volume 653 between the first and second
portions of the second fluid fin pack 607. In the volume between
the first and second fin pack portions of the second fluid circuit,
the intake air gases make a general U-turn to enter the second
portion of the second fluid fin pack 607. After travelling through
the second portion of the second fluid fin pack 607, the intake air
gases enter the second portion of the second gas valve body
assembly 651 and exit through the second gas outlet portion 616 of
the second gas valve body assembly.
[0167] For ease of construction, one gas control valve assembly 650
is welded to the heat exchanger 652 and the second gas control
valve assembly 651 is joined to the heat exchanger with a gasket
(not shown) and fasteners 612 at a bolted flange 611. Other
combinations of joining the first and second gas control valves to
the heat exchanger 652 could be employed. A side cover 630
surrounds the heat exchanger plates 631 and fin packs 609 and 607
to cooperate with the valve assemblies 650 and 651 to enclose both
fluid streams. FIG. 27a illustrates the locating features 619 in
the heat exchanger plates 631 that are used to locate the fin packs
609 and 607 in place prior to brazing.
[0168] The heat exchanger plate 631 is shown alone in FIG. 27b. In
this embodiment, the heat exchanger plate 631 is common throughout
the heat exchanger core. When assembling the heat exchanger core,
each heat exchanger plate 631 is rotated 180 degrees and stacked
upon the previous heat exchanger plate 631. The heat exchanger
plate has a side edge 632 and an end side 633. The side edges 632
and end side 633 of a first heat exchanger plate 631 cooperate with
an adjacent heat exchanger plate 631 to enclose the fin packs, form
the volumes 610 and 653, as well as keep both fluids separate. In
other embodiments there are two different heat exchanger plate
shapes that are alternately used to build up the heat exchanger
core.
[0169] For clarity as to the assembly of heat exchanger plates 631
and fin packs 609 and 607, FIG. 27d shows the opening 635 for the
first fluid to communicate with the first valve assembly 650 and
the opening 634 for the second fluid to communicate with the second
valve assembly 651. FIG. 27d also clearly shows how the first
volume 610 is formed between the heat exchanger plates 631, the
heat exchanger end side 633, and the first fluid fin pack 609.
Similarly, the second volume 653 is formed between the heat
exchanger plates 631, the heat exchanger end side 633, and the
second fluid fin pack 607.
[0170] Another EGHR assembly 700 is shown in FIG. 28. In this
embodiment, the valve body 701 contains the working fluid inlet
conduit 710 and the working fluid outlet conduit 711. The heat
exchanger assembly 702 is of the parallel plate style.
[0171] The heat exchanger assembly of FIG. 28 is illustrated in
FIG. 29. The heat exchanger cooling plates 720 are parallel to the
valve plate when the valve is in bypass mode. The heat exchanger
coolant inlet tube 716 and coolant outlet tube 717 mate up with
respective coolant conduits in the valve body assembly. The heat
exchanger core is contained in a heat exchanger housing which is
comprised of a side cover plate 708 and a bottom plate 709. The top
of the heat exchanger core has a gas leakage prevention plate 707
and a top valve plate stop 718 that cooperates with the valve plate
of the valve assembly. The side cover plate 708 forms the inlet
exhaust gas header 728 as well as the exhaust gas outlet header
729.
[0172] FIG. 30 shows the heat exchanger core with a partial section
of the gas leakage prevention plate 707 and a partial section of
the side leakage prevention plate 726. The coolant header gas
leakage prevention plate 725 provides a gas flow restriction to
exhaust gases trying to flow around the coolant headers. These
three leakage prevention plates fill gaps between the coolant
plates 720 and adjacent components through which exhaust gas could
bypass the heat exchanger core. Fin packs 719 ensure good heat
transfer from the exhaust gases to the cooling plates 720. Coolant
diverter ribs 727 help to uniformly distribute the coolant flow
over the entire surface of the cooling plates 720 to achieve good
heat transfer and avoid hot spots and durability issues in the heat
exchanger core. Coolant enters the heat exchanger core through a
coolant inlet tube 716 and exits through a coolant outlet tube
717.
[0173] FIG. 31 illustrates how the coolant inlet conduit 710 and
the coolant outlet conduit 711 in the valve body 701 cooperate with
the heat exchanger inlet coolant tube 716 and outlet coolant tube
717 to create a continuous coolant circuit. The heat exchanger
coolant tubes are sealed in the valve body coolant conduits with
the aid of o-ring seals 740. The cross section of FIG. 31 also
shows how the cooling plates 720 join together to form the heat
exchanger coolant inlet header 733 and the heat exchanger coolant
outlet header 732. Gas blockage features 722 are stamped into the
cooling plates 720 to prevent exhaust gases from bypassing the
primary heat exchanger surfaces and fin packs in the region between
the coolant headers.
[0174] An alternative embodiment to the heat exchanger shown in
FIGS. 28 to 31 would have a similar structure for the heat
exchanger core shown in FIG. 30, only the working fluid inlet 716
and outlet 717 would pass through the bottom cover 709 rather than
connecting into the valve body 701. Such an arrangement may be
desirable in the case that the valve body 701 is a fabricated
wrought structure rather than made from a casting.
[0175] The EGHR valve housings described here may be manufactured
as a single, integrally formed component and may be cast or
fabricated from wrought materials. A material from which the valve
housing is formed may be selected depending on a range of
temperatures and/or other operating conditions that the EGHR system
may be operating under in a given application. For applications in
which the material of the valve housing will reach temperatures of
about eight-hundred degrees Celsius (800.degree. C.) during
operation of the EGHR system, the valve housing may be formed from
a ferritic cast iron, for example. For applications in which the
material of the valve housing will reach temperatures of more than
eight-hundred degrees Celsius (800.degree. C.) during operation of
the EGHR system, the valve housing may be formed from austenitic
cast iron or a heat-resistant steel, for example. The valve shaft
and valve diverter plate may be formed from a steel alloy such as a
heat-resistant wrought steel, for example, and/or any other
suitable material.
[0176] The heat exchanger assemblies may include a heat exchanger
core defining generally parallel exhaust gas flow channels in
communication with the heat exchange conduits in the valve housing.
The exhaust gas flow channels may direct the exhaust gases in a
two-pass, generally U-shaped flow path when the diverter plate is
in the heat-exchange position. This allows the exhaust gas to
contact more surface area of the entire heat exchanger core. A
first portion of the exhaust gas flow channels may be formed by a
part of the heat exchanger core disposed upstream of the diverter
plate and the second portion of the exhaust gas flow channels may
be formed by a part of the heat exchanger core disposed downstream
of the diverter plate.
[0177] When the valve diverter plate is in the bypass position,
exhaust gases may enter the valve housing through the inlet opening
and may flow through the bypass conduit to bypass the heat
exchanger assembly. In this operating mode, little or no heat will
be transferred from the exhaust gas to the working fluid in the
heat exchanger assembly.
[0178] An additional benefit of the EGHR valve assemblies shown
here is that the potential for internal exhaust gas leakage around
the diverter plate and through the heat exchanger core is low when
the diverter plate is in the bypass position. This potential for
internal leakage is low because the pressure drop through the
bypass conduit is minimal, thus minimizing the root cause that
could drive unwanted flow past the diverter plate and into the heat
exchanger core. This internal flow leakage is undesirable because
it would increase heat transfer between the exhaust gases and the
heat exchanger working fluid when it is unwanted. Furthermore, if
and when exhaust gases do leak past the valve diverter plate and
into the heat exchanger core when the valve diverter plate is in
the bypass position, minimal unwanted heat transfer will result
because the leaked gases may be prevented from flowing past the
diverter plate a second time to reach the outlet opening.
[0179] Furthermore, the substantial lack of leakage around the
diverter plate in the bypass position and the physical separation
between the bypass conduit and the heat exchanger assembly allows
the flow of exhaust gas entering the inlet opening to flow through
the valve housing in a manner that substantially thermally isolates
the exhaust gas from the working fluid in the heat exchanger
assembly. Accordingly, very little or no heat transfer may occur
therebetween in the bypass mode when such heat transfer may be
undesirable. If any small amount of leakage past the diverter plate
were to occur when the diverter plate is in the bypass position,
the velocity of flow once the exhaust gas leaked past the diverter
plate would be very low and would be prevented or restricted from
flowing into the heat exchanger assembly or leaking past the
diverter plate a second time and reaching the outlet opening.
[0180] The EGHR systems presented here can be utilized as an
independent or self-contained system that can be inserted into an
exhaust gas stream wherever there is sufficient packaging space. It
should be noted that these EGHR systems can be integrated into
other components in the exhaust system.
[0181] While the following examples and discussion generally relate
to exhaust gas heat recovery applications, the general concepts
discussed herein are also applicable to other "exhaust
applications" such as thermal protection of exhaust components, or
EGR systems, for example. The principles of the present disclosure
can be employed in exhaust systems associated with internal or
external combustion systems for stationary or transportation
applications. It will be appreciated that an assembly including the
valve housings and heat exchangers described above may be used to
transfer heat between other fluids in other applications (e.g.,
charge air cooling applications, lubricant heating applications,
etc.). Therefore, the principles of the present disclosure are not
limited in application to transferring heat from engine exhaust gas
to a working fluid. In some embodiments, the valve assembly and
heat exchanger could be used to transfer heat between a working
fluid and ambient air or air to be drawn into an engine for
combustion.
[0182] In some embodiments, the EGHR systems may be configured to
transfer heat from exhaust gases directly or indirectly to
additional or alternative vehicle fluids, such as lubricants for an
engine, a transmission, an axle, and/or a differential, for
example, and/or any other fluid. For example, a lubricant or other
fluid may flow into the heat exchanger core of the heat exchanger
assembly to absorb heat from the exhaust gas when the diverter
plate is not in the bypass position. In this manner, the EGHR
system may transfer heat from exhaust gas to the lubricant and/or
other fluid to optimize a viscosity of the fluid, for example, to
improve the performance and/or fuel-economy of the vehicle.
[0183] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
* * * * *