U.S. patent application number 12/915764 was filed with the patent office on 2012-05-03 for method for controlling exhaust gas heat recovery systems in vehicles.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS, INC.. Invention is credited to Teresa L. Cerbolles, Brian L. Spohn.
Application Number | 20120102952 12/915764 |
Document ID | / |
Family ID | 45935941 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120102952 |
Kind Code |
A1 |
Spohn; Brian L. ; et
al. |
May 3, 2012 |
METHOD FOR CONTROLLING EXHAUST GAS HEAT RECOVERY SYSTEMS IN
VEHICLES
Abstract
A method of operating an exhaust gas heat recovery (EGHR) system
in a vehicle including an engine, a transmission, and an EGHR heat
exchanger is provided. The method includes monitoring an engine
water temperature and may include monitoring a transmission oil
temperature and an ambient air temperature. The method includes
comparing the monitored engine water temperature to one or more
calibrated engine temperatures. Based upon the monitored
temperatures and comparison to the calibrated temperatures, the
method controls a two-way valve. The two-way valve is configured to
be set to one of an engine position and a transmission position.
The engine position allows heat-exchange communication between the
EGHR heat exchanger and the engine, and the transmission position
allows heat-exchange communication between the EGHR heat exchanger,
the transmission, and the engine.
Inventors: |
Spohn; Brian L.; (Holly,
MI) ; Cerbolles; Teresa L.; (Troy, MI) |
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS,
INC.
Detroit
MI
|
Family ID: |
45935941 |
Appl. No.: |
12/915764 |
Filed: |
October 29, 2010 |
Current U.S.
Class: |
60/645 |
Current CPC
Class: |
F16H 57/0413 20130101;
Y02T 10/16 20130101; Y02T 10/12 20130101; F01N 5/02 20130101; F01P
2060/16 20130101; F01N 2240/02 20130101 |
Class at
Publication: |
60/645 |
International
Class: |
F01K 13/00 20060101
F01K013/00 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0001] This invention was made with U.S. Government support under
Agreement No. PHEV DOE GMT311/166 awarded by the Department of
Energy. The U.S. Government may have certain rights in this
invention.
Claims
1. A method of operating an exhaust gas heat recovery (EGHR) system
in a vehicle including an engine, a transmission, and an EGHR heat
exchanger, the method comprising: controlling a two-way valve,
wherein the two-way valve is configured to be set to one of an
engine position and a transmission position, wherein the engine
position allows heat-exchange communication between the EGHR heat
exchanger and the engine and the transmission position allows
heat-exchange communication between the EGHR heat exchanger, the
transmission, and the engine; monitoring an engine water
temperature; comparing the monitored engine water temperature to a
calibrated first engine temperature; and if the monitored engine
water temperature is below the calibrated first engine temperature,
setting the two-way valve to the engine position.
2. The method of claim 1, further comprising: monitoring a
transmission oil temperature; comparing the monitored transmission
oil temperature to a calibrated first transmission temperature; and
if the monitored transmission oil temperature is below the
calibrated first transmission temperature and the monitored engine
water temperature is below the calibrated first engine temperature,
setting the two-way valve to the transmission position.
3. The method of claim 2, further comprising: monitoring an ambient
air temperature; comparing the monitored ambient air temperature to
a calibrated hot ambient temperature; if the monitored ambient air
temperature is greater than the calibrated hot ambient temperature,
comparing the monitored engine water temperature to a calibrated
extreme engine temperature; and if the monitored engine water
temperature is less than the calibrated extreme engine temperature,
setting the two-way valve to the engine position.
4. The method of claim 3, wherein the vehicle further includes a
transmission radiator, and further comprising: if the monitored
engine water temperature is greater than the calibrated extreme
engine temperature, comparing the monitored transmission oil
temperature to a calibrated extreme transmission temperature; and
if the monitored transmission oil temperature is below the
calibrated extreme transmission temperature, setting the two-way
valve to the transmission position, such that the transmission
radiator is in heat-exchange communication with the engine.
5. The method of claim 4, further comprising: if the monitored
engine water temperature is greater than the calibrated extreme
engine temperature and the monitored transmission oil temperature
is greater than the calibrated extreme transmission temperature,
setting the two-way valve to the engine position, such that the
transmission radiator is not in heat-exchange communication with
the engine.
6. The method of claim 5, further comprising: comparing the
monitored ambient air temperature to one of a calibrated cold
ambient temperature, a calibrated mild ambient temperature, and the
calibrated hot ambient temperature; if the monitored ambient air
temperature is below the calibrated cold ambient temperature,
comparing the monitored engine water temperature to a calibrated
second engine temperature, wherein the calibrated second engine
temperature is greater than the calibrated first engine
temperature; and if the monitored engine water temperature is below
the calibrated second engine temperature, setting the two-way valve
to the engine position.
7. The method of claim 6, further comprising: monitoring for an
auto-stop mode, wherein the auto-stop mode occurs when the engine
is not producing positive torque; if the engine is in the auto-stop
mode and if the monitored ambient air temperature is below the
calibrated cold ambient temperature, comparing the monitored
transmission oil temperature to a calibrated second transmission
temperature, wherein the calibrated second transmission temperature
is less than the calibrated first transmission temperature; and if
the monitored transmission oil temperature is below the calibrated
second transmission temperature, setting the two-way valve to the
transmission position.
8. The method of claim 7, wherein the calibrated hot ambient
temperature is seventeen degrees Celsius.
9. The method of claim 8, wherein the calibrated cold ambient
temperature is eight degrees Celsius.
10. A method of operating an exhaust gas heat recovery (EGHR)
system in a vehicle including an engine, a transmission, a
transmission radiator, and an EGHR heat exchanger, the method
comprising: controlling a two-way valve, wherein the two-way valve
is configured to be set to one of an engine position and a
transmission position, wherein the engine position allows
heat-exchange communication between the EGHR heat exchanger and the
engine and the transmission position allows heat-exchange
communication between the EGHR heat exchanger, the transmission,
and the engine; monitoring an engine water temperature; monitoring
a transmission oil temperature; monitoring an ambient air
temperature; and comparing the monitored ambient air temperature to
a calibrated hot ambient temperature, and: if the monitored ambient
air temperature is greater than the calibrated hot ambient
temperature, comparing the monitored engine water temperature to a
calibrated extreme engine temperature, if the monitored engine
water temperature is less than the calibrated extreme engine
temperature, setting the two-way valve to the engine position, if
the monitored engine water temperature is greater than the
calibrated extreme engine temperature, comparing the monitored
transmission oil temperature to a calibrated extreme transmission
temperature, and if the monitored transmission oil temperature is
below the calibrated extreme transmission temperature, setting the
two-way valve to the transmission position, such that the
transmission radiator is in heat-exchange communication with the
engine.
11. The method of claim 10, further comprising: if the monitored
engine water temperature is greater than the calibrated extreme
engine temperature and the monitored transmission oil temperature
is greater than the calibrated extreme transmission temperature,
setting the two-way valve to the engine position, such that the
transmission radiator is not in heat-exchange communication with
the engine.
12. The method of claim 11, further comprising: comparing the
monitored ambient air temperature to one of a calibrated cold
ambient temperature, a calibrated mild ambient temperature, and the
calibrated hot ambient temperature; if the monitored ambient air
temperature is below the calibrated cold ambient temperature,
comparing the monitored engine water temperature to a calibrated
second engine temperature, wherein the calibrated second engine
temperature is greater than the calibrated first engine
temperature; and if the monitored engine water temperature is below
the calibrated second engine temperature, setting the two-way valve
to the engine position.
13. The method of claim 12, further comprising: monitoring for an
auto-stop mode, wherein the auto-stop mode occurs when the engine
is not producing positive torque; if the engine is in the auto-stop
mode and if the monitored ambient air temperature is below the
calibrated cold ambient temperature, comparing the monitored
transmission oil temperature to a calibrated second transmission
temperature, wherein the calibrated second transmission temperature
is less than the calibrated first transmission temperature; and if
the monitored transmission oil temperature is below the calibrated
second transmission temperature, setting the two-way valve to the
transmission position.
Description
TECHNICAL FIELD
[0002] This disclosure relates to control of exhaust gas heat
reclaim, recovery, or recirculation systems for vehicles.
BACKGROUND
[0003] Internal combustion engines produce energy by combustion of
a fuel with an (usually) air in a combustion chamber. The
combustion process in internal combustion engines produces power to
move the vehicle, usually converting the linear motion within the
combustion chamber to rotation, but also produces heat.
[0004] The combustion products--uncombusted fuel, unused oxygen,
and byproducts, in the form of (often) hot exhaust gases--are
expelled through an exhaust system taking the combustion products
away from the engine. Exhaust gas heat recovery is designed to
remove heat from the exhaust gas of engines and transfer it
elsewhere, such as to a water circuit. The interior of the car may
be warmed using exhaust heat, or thermoelectric devices may produce
electricity from the exhaust heat.
SUMMARY
[0005] A method of operating an exhaust gas heat recovery (EGHR)
system in a vehicle including an engine, a transmission, and an
EGHR heat exchanger is provided. The method includes monitoring an
engine water temperature and may include monitoring a transmission
oil temperature and an ambient air temperature. The method includes
comparing the monitored engine water temperature to one or more
calibrated engine temperatures. Based upon the monitored
temperatures and comparison to the calibrated temperatures, the
method controls a two-way valve.
[0006] The two-way valve is configured to be set to one of an
engine position and a transmission position. The engine position
allows heat-exchange communication between the EGHR heat exchanger
and the engine, and the transmission position allows heat-exchange
communication between the EGHR heat exchanger, the transmission,
and the engine.
[0007] The method may include comparing the monitored engine water
temperature to a calibrated first engine temperature, and if the
monitored engine water temperature is below the calibrated first
engine temperature, setting the two-way valve to the engine
position. The method may further include comparing the monitored
transmission oil temperature to a calibrated first transmission
temperature, and if the monitored transmission oil temperature is
below the calibrated first transmission temperature and the
monitored engine water temperature is below the calibrated first
engine temperature, setting the two-way valve to the transmission
position.
[0008] The above features and advantages, and other features and
advantages, of the present invention are readily apparent from the
following detailed description of some of the best modes and other
embodiments for carrying out the invention, as defined in the
appended claims, when taken in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic diagram of an exemplary hybrid vehicle
powertrain having an exhaust gas heat recovery (EGHR) system in
communication with an engine and a transmission;
[0010] FIG. 2 is a schematic flow chart diagram of an algorithm or
method for controlling an EGHR system, such as that shown in FIG.
1;
[0011] FIG. 3 is a schematic flow chart of a subroutine of the
method shown in FIG. 2, showing portions of the method for mild
ambient temperatures;
[0012] FIG. 4 is a schematic flow chart of another subroutine of
the method shown in FIG. 2, showing portions of the method for cold
ambient temperatures; and
[0013] FIG. 5 is a schematic flow chart of another subroutine of
the method shown in FIG. 2, showing portions of the method for
extreme or hot ambient temperatures.
DETAILED DESCRIPTION
[0014] Referring to the drawings, wherein like reference numbers
correspond to like or similar components whenever possible
throughout the several figures, there is shown in FIG. 1 a
schematic diagram of an exhaust gas heat recovery (EGHR) system,
referred to generally as EGHR system 10. The EGHR system 10 is in
selective fluid flow and heat-exchange communication with an
internal combustion engine 12 and a transmission 14 of a vehicle
(not shown).
[0015] The engine 12 is drivingly connected to the transmission 14,
which may be a hybrid transmission having one or more electric
machines (not shown). Alternatively, the vehicle may include one or
more electric machines acting directly on the engine output or the
transmission input. The engine 12 releases exhaust gas through an
exhaust pipe or exhaust system 16, which includes an EGHR heat
exchanger 18, as explained herein.
[0016] While the present invention is described in detail with
respect to automotive applications, those skilled in the art will
recognize the broader applicability of the invention. Those having
ordinary skill in the art will recognize that terms such as
"above," "below," "upward," "downward," et cetera, are used
descriptively of the figures, and do not represent limitations on
the scope of the invention, as defined by the appended claims.
[0017] FIG. 1 shows a highly-schematic control architecture or
control system 20 for the EGHR system 10. The control system 20 may
include one or more components (not separately shown) with a
storage medium and a suitable amount of programmable memory, which
are capable of storing and executing one or more algorithms or
methods to effect control of the EGHR system 10. Each component of
the control system 20 may include distributed controller
architecture, such as a microprocessor-based electronic control
unit (ECU). Additional modules or processors may be present within
the control system 20.
[0018] An engine water circuit 22 moves coolant or water from the
engine 12 through, eventually, the EGHR heat exchanger 18. The
engine water circuit 22 is supplied with pressurized coolant by a
primary pump (not separately shown) incorporated with the engine
12. The primary pump may be a mechanical pump driven by rotation of
the engine 12. Depending upon the operating conditions of the EGHR
system 10, the coolant in the engine water circuit 22 may be heated
by the exhaust gases from the engine 12. A transmission water
circuit 24 is selectively connected to the engine water circuit 22
by a two-way valve 26, which allows heat-flow or heat-exchange
communication between the transmission water circuit 24 and the
engine water circuit 22.
[0019] The two-way valve 26 is configured to be selectively
controlled or set to one of an engine position and a transmission
position. The engine position of the two-way valve 26 allows
heat-exchange communication between the EGHR heat exchanger 18 and
the engine 12. The transmission position allows heat-exchange
communication between the EGHR heat exchanger 18 and both the
transmission 14 and the engine 12. When the two-way valve 26 is in
the transmission position, the transmission water circuit 24 is
supplied with coolant or water from the engine water circuit 22 by
the primary pump, if the primary pump is operating. A transmission
oil circuit 28 circulates lubricating and cooling oil from the
transmission 14. The two-way valve 26 may be electrically operated,
fluid operated (such as by a pilot valve), or operated in any
suitable manner to move between the engine position and the
transmission position.
[0020] The exact boundaries and paths of the engine water circuit
22 and the transmission water circuit 24 may vary slightly. The
engine water circuit 22 provides communication between the engine
12 and the EGHR heat exchanger 18. The transmission water circuit
24 provides communication between the engine water circuit 22 and
the transmission oil circuit 28. The two-way valve 26 has three
ports: a first port or inlet port brings water or coolant in from
the heater core 30 or directly from the coolant outlet of the
engine 12; a second port links the inlet flow to the engine water
circuit 22 such that only the engine water circuit 22 has flow; and
a third port links the inlet flow to the transmission water circuit
24.
[0021] In addition to the EGHR heat exchanger 18, the EGHR system
10 includes other heat exchangers or radiators. A heater core 30
allows heat to be transferred from the coolant or water leaving the
engine 12 to the cabin (passenger compartment) of the vehicle. An
engine radiator 32 is a water-to-air heat exchanger configured to
selectively dissipate heat from the engine 12 to ambient air
flowing through the engine radiator 32. A thermostat (not shown)
may be used to control flow of coolant from the engine 12 through
the engine radiator 32. A transmission radiator 34 is an oil-to-air
heat exchanger configured to selectively dissipate heat from the
transmission oil circuit 28 of the transmission 14 to ambient air
flowing through the transmission radiator 34.
[0022] While the engine radiator 32 and the transmission radiator
34 are shown schematically side-by-side, in many applications of
the EGHR system 10, the engine radiator 32 and transmission
radiator 34 would be placed one in front of the other at an area of
high airflow into the underhood area of the vehicle. However, the
engine radiator 32 and the transmission radiator 34 may be located
elsewhere in the vehicle. As used herein, heat exchanger may refer
to myriad different devices for exchanging heat energy between two
mediums or two systems.
[0023] The actual direction of flow of heat energy between any
sides of a heat exchanger is controlled by temperature difference
across the specific heat exchanger. For example, if the engine 12
were very cold and the thermostat allowed circulation through the
engine radiator 32 on a very hot day, the engine radiator 32 would
warm the coolant until it reached (approximately) the ambient
temperature and would then cool the engine coolant when the coolant
temperature exceeded the ambient temperature.
[0024] A central heat exchanger 36 is an oil-to-water heat
exchanger which allows heat-exchange communication between the
transmission oil circuit 28 of the transmission 14 and the
transmission water circuit 24. The central heat exchanger 36 allows
heat to be transferred from the transmission water circuit 24 to
the transmission oil circuit 28 in order to warm the transmission
14 and reduce slip loss. Furthermore, as discussed herein, the
central heat exchanger 36 also allows the transmission 14 and
transmission radiator 34 to dissipate excess heat from the engine
12 during hot or extreme conditions.
[0025] An auxiliary pump 38 is disposed within the engine water
circuit 22. The auxiliary pump 38 may be used to add pressure and
increase flow through the engine water circuit 22 and, selectively,
the transmission water circuit 24 when the need arises.
Furthermore, when the engine 12 is turned off or un-fueled by the
hybrid vehicle controls (not shown separately) the auxiliary pump
38 may be used as the main pressure source for the engine water
circuit 22 and the transmission water circuit 24. Therefore, the
auxiliary pump 38 may be used to supplement the primary pump
incorporated into the engine 12, may be used as the only pump when
the engine 12 and the primary pump are not operating, or may be
used as the sole pump for the engine water circuit 22 and the
transmission water circuit 24.
[0026] An EGHR bypass valve 42 controls flow of exhaust gases
through the EGHR heat exchanger 18. The EGHR bypass valve 42 is
shown in its non-bypass position, which allows flow of exhaust
gases through the EGHR heat exchanger 18 and allows heat-exchange
communication between the exhaust gases and the engine water
circuit 22. When the EGHR bypass valve 42 is switched, flipped, or
otherwise actuated to a bypass position--shown in FIG. 1 as a
dashed line and labeled as element 43--exhaust gases leaving the
engine 12 are not allowed to pass through the EGHR heat exchanger
18.
[0027] The EGHR bypass valve 42 may be controlled by a solenoid, a
mechanical thermostat, a wax motor, vacuum actuator, or other
suitable controls, and may be switched between the non-bypass
position and the bypass position at varying temperatures and
conditions. The EGHR bypass valve 42 may be controlled based upon
the monitored engine temperature or based upon the temperature of
the coolant flowing through the EGHR heat exchanger 18. For
example, and without limitation, the EGHR bypass valve 42 may be a
wax motor driven by coolant temperatures of seventy-two degrees
Celsius or greater in the engine water circuit 22. The set-point
temperature for the EGHR bypass valve 42, and other settings within
the EGHR system 10, is exemplary and illustrative only. The
specific values for set points will be determined based upon the
specific configuration of the EGHR system 10 and the vehicle into
which it is incorporated.
[0028] A transmission thermostat 44 controls flow between the
transmission oil circuit 28 and the transmission radiator 34. The
transmission thermostat 44 is shown in its direct return position,
which directs flow of exhaust returning from the central heat
exchanger 36 back to the transmission 14 without passing through
the transmission radiator 34. When the transmission thermostat 44
is switched, flipped, or otherwise actuated to a radiator
position--shown in FIG. 1 as a dashed line and labeled as element
45--oil returning from the central heat exchanger 36 is directed
through the transmission radiator 34 before returning to the
transmission 14.
[0029] When the transmission thermostat 44 is in the radiator
position (as shown as 45 in FIG. 1) heat may be transferred or
communicated from either the transmission 14 or the central heat
exchanger 36 to the ambient air via the transmission radiator 34.
For example, and without limitation, the transmission thermostat 44
may be a mechanical or an electromechanical thermostat opened by
oil temperatures greater than eighty-two degrees Celsius or greater
than ninety-two degrees Celsius in the transmission oil circuit 28,
depending upon the size of the transmission radiator 34.
[0030] Flow arrows are shown in FIG. 1 in order to illustrate the
path and direction of flow through some areas and components of the
EGHR system 10 during specific operating modes. The EGHR bypass
valve 42 is shown in the non-bypass modes so that exhaust gases are
flowing through the EGHR heat exchanger 18. The transmission
thermostat 44 is shown in the direct return position so that oil is
not passing through the transmission radiator 34. The two-way valve
26 is shown in the transmission position so that the transmission
water circuit 24 is in fluid communication with the engine water
circuit 22. When the two-way valve 26 is in the transmission
position the central heat exchanger 36 allows heat-exchange
communication between the engine water circuit 22 (via the
transmission water circuit 24) and the transmission oil circuit
28.
[0031] An ambient air sensor 46 monitors the temperature of the
ambient air around (and flowing through) the vehicle and is in
communication with the control system 20. Either the control system
20 or the ambient air sensor 46 compares the monitored ambient air
temperature to one of a calibrated cold ambient temperature, a
calibrated mild ambient temperature, and a calibrated hot ambient
temperature. Each of the calibrated temperatures referred to herein
may be determined through testing or modeling of the EGHR system 10
and the vehicle. Furthermore, the calibrated temperatures may be
altered throughout the lifetime of the vehicle based upon the
lifecycle of the vehicle or components thereof or based upon
learned operating characteristics of the vehicle of having the EGHR
system 10. The values given for the calibrated temperatures are
illustrative and exemplary only, and the values are not intended to
limit the scope of the invention unless included in the claims
defining the invention.
[0032] Referring now to FIGS. 2-5, and with continued reference to
FIG. 1, there are shown schematic flow chart diagrams of an
algorithm or method 200 for controlling exhaust gas heat recovery,
such as the EGHR system 10 shown in FIG. 1. The exact order of the
steps of the algorithm or method 200 shown in FIGS. 2-5 is not
required. Steps may be reordered, steps may be omitted, and
additional steps may be included. Furthermore, the method 200 may
be a portion or sub-routine of another algorithm or method.
[0033] For illustrative purposes, the method 200 may be described
with reference to the elements and components shown and described
in relation to FIG. 1 and may be executed by the control system 20.
However, other components may be used to practice the method 200
and the invention defined in the appended claims. Any of the steps
may be executed by multiple components within the control system
20.
[0034] FIG. 2 shows a high-level diagram of the method 200. FIG. 3
shows a mild sub-routine 300 of the method 200 occurring during
mild ambient temperatures; FIG. 4 shows a cold sub-routine 400 of
the method 200 occurring during cold ambient temperatures; and FIG.
5 shows a hot sub-routine 500 of the method 200 occurring during
hot ambient temperatures.
[0035] Step 210: Start.
[0036] The method 200 may begin at a start or initialization step,
during which time the method 200 is monitoring operating conditions
of the vehicle and of the EGHR system 10. Initiation may occur in
response to the vehicle operator inserting the ignition key or in
response to specific conditions being met, such as in response to a
negative torque request (braking or deceleration request) from the
driver or cruise control module combined with a predicted or
commanded downshift. Alternatively, the method 200 may be running
constantly or looping constantly whenever the vehicle is in
use.
[0037] Step 212: Determine Ambient, Transmission, and Engine
Temperatures.
[0038] The method 200 includes monitoring or determining
temperatures of different components or conditions. An ambient air
temperature is monitored, such as with the ambient air sensor 46.
An engine water temperature is also monitored. The engine water
temperature may be determined from within the engine 12, at the
entrance to the engine water circuit 22, or from another location
of the engine water circuit 22. A transmission oil temperature is
also monitored. The transmission oil temperature may be determined
from within the transmission 14, at the entrance to the
transmission oil circuit 28, or from another location.
[0039] Step 214: Compare Ambient Air to Calibrated
Temperatures.
[0040] The method 200 compares the monitored ambient air
temperature to the calibrated cold ambient temperature, the
calibrated mild ambient temperature, and the calibrated hot ambient
temperature to determine the ambient air temperature range. For
example, and without limitation, the calibrated cold ambient
temperature may be any monitored ambient temperature below eight
degrees Celsius; the calibrated mild ambient temperature may be any
monitored ambient temperature between eight and seventeen degrees
Celsius; and the calibrated hot ambient temperature may be any
monitored ambient temperature above seventeen degrees Celsius.
[0041] If the method 200 determines that the temperature is within
the mild range, the method 200 proceeds to the mild sub-routine
300. If the method 200 determines that the temperature is within
the cold range, the method 200 proceeds to the cold sub-routine
400. If the method 200 determines that the temperature is within
the hot range, the method 200 proceeds to the hold sub-routine
500.
[0042] Mild Sub-Routine 300.
[0043] Referring now to FIG. 3, and with continued reference to
FIGS. 1-2, there is shown a schematic flow chart diagram of the
mild sub-routine 300. The mild sub-routine 300 is a portion of the
method 200 shown in FIG. 2 and is represented in FIG. 2 as a part
of the block denoted by the number 300. The steps shown in the flow
chart diagram of FIG. 3 may be only a portion of the mild
sub-routine 300, such that the method 200 may include further steps
within the mild sub-routine 300. The mild temperature range occurs
when the ambient air temperature is monitored to be between the
cold temperature range and the hot temperature range.
[0044] Step 310: Engine Temperature Less than Calibrated First
Temperature?
[0045] The method 200 includes comparing the monitored engine water
temperature to a calibrated first engine temperature. For example,
and without limitation, the calibrated first engine temperature may
be approximately sixty degrees Celsius.
[0046] As viewed in FIGS. 3-5, basic decision steps answered
positively (as a yes) follow the path labeled with a "+" sign (the
mathematical plus or addition operator). Similarly, decision steps
answered negatively (as a no) follow the path labeled with a "-"
sign (the mathematical minus or subtraction operator).
[0047] Step 312: Engine-Warming Mode.
[0048] If the method 200 determines that the monitored engine water
temperature is below the calibrated first engine temperature, the
method 200 proceeds to an engine-warming mode for the EGHR system
10. Depending upon the configuration of the engine 12, operating
below the calibrated first engine temperature may affect fuel
efficiency. Therefore, the method 200 places the EGHR system 10
into the engine-warming mode to increase the temperature of the
engine 12 with any available heat from the exhaust gases through
the EGHR heat exchanger 18.
[0049] Step 314: Valve Set to Engine Position.
[0050] If the monitored engine water temperature is below the
calibrated first engine temperature, then execution of the
engine-warming mode includes controlling (setting) the two-way
valve 26 to the engine position. The control system 20 may actuate
the two-way valve 26 based upon the determination of the method
200. Furthermore, the EGHR bypass valve 42 is calibrated to remain
in the non-bypass position because the temperature of the coolant
passing through the engine water circuit 22 is insufficient to
actuate or trigger the bypass valve.
[0051] When in the engine-warming mode, hot exhaust gases travel
through the exhaust system 16 and are directed through the EGHR
heat exchanger 18 by the EGHR bypass valve 42. Coolant leaves the
engine 12 and passes through the heater core 30. The two-way valve
26 prevents flow of the coolant through the transmission water
circuit 24, so the coolant is circulated only through the engine
water circuit 22. The exhaust gases transfer heat to the coolant in
the engine water circuit 22, which returns to the engine 12 and
warms the engine 12.
[0052] Although the transmission water circuit 24 has no flow, the
transmission oil circuit 28 may be circulating oil through the
central heat exchanger 36. The temperature of the transmission 14
is substantially controlled by heat generated within the
transmission 14 and by heat dissipated through the transmission
radiator 34 if the transmission thermostat 44 moves to the radiator
position.
[0053] The method 200 may stay in engine-warming mode with the
two-way valve 26 set to the engine position for a pre-determined or
a calculated time period. However, the method 200 may be looping or
iterating repeatedly and the engine-warming mode may continue until
a subsequent loop determines that conditions of the EGHR system 10
have changed, and the method 200 results in another operating
mode.
[0054] Step 316: Transmission Temperature Less than Calibrated
First Temperature?
[0055] If the method 200 determines that the monitored transmission
oil temperature is at or above (i.e. not below) the calibrated
first engine temperature, then the method 200 does not need to
enter the engine-warming mode. The method 200 then includes
comparing the monitored transmission oil temperature to a
calibrated first transmission temperature. For example, and without
limitation, the calibrated first transmission temperature may be
approximately eighty degrees Celsius.
[0056] Depending upon the configuration of the transmission 14,
operating below the calibrated first transmission temperature may
affect fuel efficiency. However, the transmission 14 may be
negatively effected if the monitored transmission oil temperature
too hot.
[0057] Step 318: Transmission-Warming Mode.
[0058] If the monitored transmission oil temperature is below the
calibrated first transmission temperature and the monitored engine
water temperature is below the calibrated first engine temperature,
then the method 200 will control the EGHR system 10 to a
transmission-warming mode. In the transmission-warming mode, heat
from the engine 12, the EGHR heat exchanger 18, or both, is
transferred through the central heat exchanger 36 to the
transmission oil circuit 28 and the transmission 14.
[0059] Step 320: Valve Set to Transmission Position.
[0060] When in the transmission-warming mode, the method 200
includes setting the two-way valve 26 to the transmission position.
When the two-way valve 26 is in the transmission position, coolant
passes through the heater core 30 and is then directed through the
transmission water circuit 24 and the central heat exchanger 36
before proceeding to the EGHR heat exchanger 18 and back to the
engine 12. Any time that the EGHR system 10 is in the
transmission-warming mode, the two-way valve 26 will be set to the
transmission position.
[0061] During the transmission-warming mode, heat from the engine
12 will be transferred through the central heat exchanger 36 to the
transmission 14. Furthermore, heat from the exhaust gases will
transfer from the EGHR heat exchanger 18 to the engine water
circuit 22 to either raise the temperature of engine 12 or to
replenish the heat transferred to the transmission 14. If the
temperature of the engine rises substantially during the
transmission-warming mode, the EGHR bypass valve 42 will close
(driven by, for example, the wax motor) to the bypass position
(shown as 43 in FIG. 1) and prevent heat from exhaust gases from
passing to the engine water circuit 22. The transmission-warming
mode is shown in FIG. 1 where the two-way valve 26 is allowing
heat-exchange communication between the EGHR heat exchanger 18, the
engine 12, and the transmission 14.
[0062] Like the engine-warming mode, the method 200 may stay in
transmission-warming mode with the two-way valve 26 set to the
transmission position for a pre-determined or a calculated time
period. However, the method 200 may be looping or iterating
repeatedly and the transmission-warming mode may continue until a
subsequent loop determines that conditions of the EGHR system 10
have changed, and the method 200 results in another operating mode.
Whenever the EGHR system 10 is in the transmission-warming mode,
the two-way valve 26 will be set to the transmission position.
[0063] Step 322: Transmission Cooling Mode.
[0064] If the monitored transmission oil temperature is above the
calibrated first transmission temperature and the monitored engine
water temperature is below the calibrated first engine temperature,
then the method 200 will control the EGHR system 10 to a
transmission cooling mode. In the transmission cooling mode, heat
from the transmission 14 is either retained within the transmission
oil circuit 28 or dissipated through the transmission radiator
34.
[0065] Step 324: Valve Set to Engine Position.
[0066] When in the transmission cooling mode, the method 200
includes setting the two-way valve 26 to the engine position. When
the two-way valve 26 is in the engine position, no coolant flow
occurs in the transmission water circuit 24. Therefore, heat is not
exchanged through the central heat exchanger 36 to the transmission
14.
[0067] During the transmission cooling mode, coolant continues to
flow through the engine water circuit 22 and the temperature of the
engine 12 will be controlled solely by the EGHR bypass valve 42.
Oil continues to circulate through the transmission oil circuit 28.
However, because no coolant is flowing through the central heat
exchanger 36, no heat will be transferred to the transmission 14.
If the temperature of the transmission 14 rises above the level
necessary to actuate or trigger the transmission thermostat 44,
fluid will flow through the transmission radiator 34 and dissipate
heat from the transmission oil circuit 28, thereby cooling the
transmission 14.
[0068] Cold Sub-Routine 400.
[0069] Referring now to FIG. 4, and with continued reference to
FIGS. 1-3, there is shown a schematic flow chart diagram of the
cold sub-routine 400. The cold sub-routine 400 is a portion of the
method 200 shown in FIG. 2 and is represented in FIG. 2 as a part
of the block denoted by the number 400. The steps shown in the flow
chart diagram of FIG. 4 may be only a portion of the cold
sub-routine 400, such that the method 200 may include further steps
within the cold sub-routine 400. The cold temperature range occurs
below the mild temperature range. The cold sub-routine 400 may be
called-up whenever the method 200 determines that the ambient
temperature is below the calibrated cold ambient temperature.
[0070] Step 410: Engine Temperature Less than Calibrated Second
Temperature?
[0071] If the monitored ambient air temperature is below the
calibrated cold ambient temperature, the method 200 includes
comparing the monitored engine water temperature to a calibrated
second engine temperature. The calibrated second engine temperature
may be the same as or different from the calibrated first engine
temperature. For example, and without limitation, the calibrated
second engine temperature may be approximately seventy-five degrees
Celsius, while calibrated first engine temperature is sixty degrees
Celsius. The calibrated second engine temperature may be greater
than the calibrated first engine temperature because the relatively
colder ambient air temperature provides less heat to the engine
12.
[0072] Step 412: Engine-Warming Mode.
[0073] If the method 200 determines that the monitored engine water
temperature is below the calibrated second engine temperature, the
method 200 proceeds to the engine-warming mode for the EGHR system
10. The method 200 places the EGHR system 10 into the
engine-warming mode to increase the temperature of the engine
12--if any heat is available from the exhaust gases--through the
EGHR heat exchanger 18.
[0074] Step 414: Valve Set to Engine Position.
[0075] Executing the engine-warming mode includes controlling or
setting the two-way valve 26 to the engine position. The control
system 20 may actuate the two-way valve 26 based upon the
determination of the method 200. Furthermore, the EGHR bypass valve
42 is calibrated to remain in the non-bypass position because the
temperature of the coolant passing through the engine water circuit
22 is insufficient to actuate or trigger the bypass valve.
[0076] As during the engine-warming mode of the mild ambient
sub-routine 300 shown in FIG. 3, when the EGHR system 10 is in the
engine-warming mode, hot exhaust gases travel through the exhaust
system 16 and are directed through the EGHR heat exchanger 18 by
the EGHR bypass valve 42. Coolant leaves the engine 12, passes
through the heater core 30, and the two-way valve 26 prevents flow
of the coolant through the transmission water circuit 24. The
coolant is circulated only through the engine water circuit 22. The
exhaust gases transfer heat to the coolant in the engine water
circuit 22, which returns to warm the engine 12.
[0077] Step 416: Engine Producing Positive Torque?
[0078] If the method 200 determines that the monitored engine water
temperature is not below the calibrated second engine temperature,
the method 200 proceeds to monitoring for an auto-stop mode.
Auto-stop mode occurs when vehicles shut down, power off, or cut
fuel to the engine 12. Alternatively stated, auto-stop mode occurs
when the engine 12 is not producing positive torque.
[0079] Step 418: Transmission-Warming Mode.
[0080] If the engine 12 is not in auto-stop mode, such that the
engine 12 is producing positive torque, then the method 200 will
control the EGHR system 10 to the transmission-warming mode. In the
transmission-warming mode, during cold ambient temperatures, heat
from the engine 12, residual heat from the EGHR heat exchanger 18,
or heat from both, is transferred through the central heat
exchanger 36 to the transmission oil circuit 28 and the
transmission 14.
[0081] Step 420: Valve Set to Transmission Position.
[0082] When in the transmission-warming mode, the method 200 sets
the two-way valve 26 to the transmission position. When the two-way
valve 26 is in the transmission position, coolant passes through
the heater core 30 and is then directed through the transmission
water circuit 24 and the central heat exchanger 36 before
proceeding to the EGHR heat exchanger 18 and back to the engine 12.
Any time that the EGHR system 10 is in the transmission-warming
mode, the two-way valve 26 will be set to the transmission
position.
[0083] During the transmission-warming mode, heat from the engine
12 will be transferred through the central heat exchanger 36 to the
transmission 14. Furthermore, heat from the exhaust gases left in
the EGHR heat exchanger 18 will transfer from the EGHR heat
exchanger 18 to the engine water circuit 22 and eventually to the
transmission 14.
[0084] Step 422: Auto-Stop Mode.
[0085] If the engine 12 is in the auto-stop mode, the engine 12 is
not producing torque and is likely not producing heat. Furthermore,
during the auto-stop mode, the auxiliary pump 38 will be turned on
to provide pressure to the engine water circuit 22 and, if
connected by the two-way valve 26, to the transmission water
circuit 24.
[0086] Step 424: Transmission Temperature Less than Calibrated
Second Temperature?
[0087] After determining that the engine 12 is in auto-stop mode,
the method 200 then includes comparing the monitored transmission
oil temperature to a calibrated second transmission temperature.
For example, and without limitation, the calibrated second
transmission temperature may be approximately seventy degrees
Celsius, which is lower than the first calibrated transmission
temperature used in the mild ambient temperature sub-routine
300.
[0088] Step 426: Transmission-Warming Mode.
[0089] If the engine 12 is in auto-stop mode and the monitored
transmission oil temperature is below the calibrated second
transmission temperature, then the method 200 will again control
the EGHR system 10 to the transmission-warming mode. In the
transmission-warming mode, during cold ambient temperatures, heat
from the engine 12, residual heat from the EGHR heat exchanger 18,
or heat from both, is transferred through the central heat
exchanger 36 to the transmission oil circuit 28 and the
transmission 14.
[0090] Step 428: Valve Set to Transmission Position.
[0091] When in the transmission-warming mode, the method 200 sets
the two-way valve 26 to the transmission position. When the two-way
valve 26 is in the transmission position, coolant passes through
the heater core 30 and is then directed through the transmission
water circuit 24 and the central heat exchanger 36 before
proceeding to the EGHR heat exchanger 18 and back to the engine
12.
[0092] During the transmission-warming mode, heat from the engine
12 will be transferred through the central heat exchanger 36 to the
transmission 14. Furthermore, heat from the exhaust gases left in
the EGHR heat exchanger 18 will transfer from the EGHR heat
exchanger 18 to the engine water circuit 22 and eventually to the
transmission 14.
[0093] Step 430: Engine-Warming Mode.
[0094] If the method 200 determines that the engine 12 is in the
auto-stop mode (not producing torque) and if the monitored
transmission oil temperature is not below the calibrated second
transmission temperature, the method 200 proceeds to the
engine-warming mode for the EGHR system 10. The method 200 places
the EGHR system 10 into the engine-warming mode to increase the
temperature of the engine 12--if any heat is available from the
exhaust gases--through the EGHR heat exchanger 18. During auto-stop
mode, additional heat in the transmission 14 may be used as
additional thermal mass to delay the next engine-on event if the
transmission 14 is above the calibrated second transmission
temperature.
[0095] Step 432: Valve Set to Engine Position.
[0096] Executing the engine-warming mode includes controlling or
setting the two-way valve 26 to the engine position. When the EGHR
system 10 is in the engine-warming mode, residual heat from hot
exhaust gases is directed through the EGHR heat exchanger 18 by the
EGHR bypass valve 42. Coolant leaves the engine 12, passes through
the heater core 30, and the two-way valve 26 prevents flow of the
coolant through the transmission water circuit 24. The exhaust
gases transfer heat to the coolant in the engine water circuit 22,
which returns to warm the engine 12.
[0097] Hot Sub-Routine 500.
[0098] Referring now to FIG. 5, and with continued reference to
FIGS. 1-4, there is shown a schematic flow chart diagram of the hot
sub-routine 500. The hot sub-routine 500 is a portion of the method
200 shown in FIG. 2 and is represented in FIG. 2 as a part of the
block denoted by the number 500. The steps shown in the flow chart
diagram of FIG. 5 may be only a portion of the hot sub-routine 500,
such that the method 200 may include further steps within the hot
sub-routine 500. The hot temperature range occurs above the mild
temperature range.
[0099] The hot sub-routine 500 may be called-up whenever the method
200 determines that the ambient temperature is above the calibrated
hot ambient temperature. When the ambient air temperature is in the
hot range, the potential for heat degradation or damage to the
engine 12 or the transmission 14 is increased.
[0100] Step 510: Transmission Temperature Less than Calibrated
First Temperature?
[0101] The method 200 again includes comparing the monitored
transmission oil temperature to the calibrated first transmission
temperature. If the monitored transmission oil temperature is below
the calibrated first transmission temperature, then the
transmission 14 is cold--even though the ambient temperature is
hot--and efficiency may be reduced.
[0102] Step 512: Transmission-Warming Mode.
[0103] If the monitored transmission oil temperature is below the
calibrated first transmission temperature and the monitored ambient
air temperature is above the calibrated hot ambient temperature,
then the method 200 will control the EGHR system 10 to a
transmission-warming mode. As in other ambient air temperatures,
such as those shown in FIGS. 3 and 4, when the EGHR system 10 is in
the transmission-warming mode, heat from the engine 12 or from the
EGHR heat exchanger 18, or both, is transferred through the central
heat exchanger 36 to the transmission oil circuit 28 and the
transmission 14.
[0104] Step 514: Valve Set to Transmission Position.
[0105] When in the transmission-warming mode, the method 200
includes setting the two-way valve 26 to the transmission position.
When the two-way valve 26 is in the transmission position, coolant
passes through the heater core 30 and is then directed through the
transmission water circuit 24 and the central heat exchanger 36
before proceeding to the EGHR heat exchanger 18 and back to the
engine 12. Any time that the EGHR system 10 is in the
transmission-warming mode, the two-way valve 26 will be set to the
transmission position.
[0106] During the transmission-warming mode, heat from the engine
12 will be transferred through the central heat exchanger 36 to the
transmission 14. Furthermore, heat from the exhaust gases will
transfer from the EGHR heat exchanger 18 to the engine water
circuit 22 to either raise the temperature of engine 12 or to
replenish the heat transferred to the transmission 14. If the
temperature of the engine rises substantially during the
transmission-warming mode, the EGHR bypass valve 42 will close
(driven by, for example, the wax motor) to the bypass position
(shown as 43 in FIG. 1) and prevent heat from exhaust gases from
passing to the engine water circuit 22.
[0107] Step 516: Transmission Temperature not Cold.
[0108] If the monitored transmission oil temperature is not below
the calibrated first transmission temperature, then the method 200
does not need to warm the transmission 14. The method 200 may then
determine whether either the engine 12 or the transmission 14 is
experiencing extremely high temperatures.
[0109] Step 518: Engine Temperature Less than Calibrated Extreme
Temperature?
[0110] The method 200 includes comparing the monitored engine water
temperature to a calibrated extreme engine temperature or a
calibrated third engine temperature. The calibrated extreme engine
temperature may be based upon temperatures above which the engine
12 is likely to degrade, if maintained for an extended period of
time. For example, and without limitation, the calibrated extreme
engine temperature may be approximately one hundred twenty degrees
Celsius.
[0111] Step 520: Engine Temperature not Extreme.
[0112] If the method 200 determines that the monitored engine water
temperature is less than the calibrated extreme engine temperature,
then the engine 12 is not experiencing extreme temperatures.
However, although warming of the engine 12 may not be needed, the
method 200 then sets the two-way valve 26 to the engine
position.
[0113] Step 522: Valve Set to Engine Position.
[0114] When the two-way valve 26 is set to the engine position, the
temperature of the engine 12 may warm, cool, or stay relatively
constant. If the temperature of the coolant in the engine water
circuit 22 is below the temperature necessary to actuate the EGHR
bypass valve 42, heat will be transferred from the exhaust gases to
the engine 12. However, if the temperature is above the level
necessary to close the EGHR bypass valve 42--by actuating, for
example, the wax motor--to the bypass position (shown as 43 in FIG.
1), exhaust gases will be prevented from passing to the engine
water circuit 22. Note also that high temperatures within the
engine 12 may trigger the engine thermostat to begin flow through
the engine radiator 32 to cool the engine 12.
[0115] Step 524: Transmission Temperature Less than Calibrated
Extreme Temperature?
[0116] If the monitored engine water temperature is greater than
the calibrated extreme engine temperature, then the engine 12 is
experiencing extreme temperatures. The method 200 then proceeds to
determine whether the excess heat in the engine 12 may be
dissipated through the transmission 14 and the transmission
radiator 34. Therefore, the method 200 includes comparing the
monitored transmission oil temperature to a calibrated extreme
transmission temperature.
[0117] The calibrated extreme transmission temperature may be based
upon temperatures above which the transmission 14 is likely to
degrade, if maintained for an extended period of time. For example,
and without limitation, the calibrated extreme transmission
temperature may be approximately one hundred ten degrees Celsius.
Note that when the temperature of the engine 12 is above the
calibrated extreme engine temperature, the engine thermostat is
likely allowing flow through the engine radiator 32 and the EGHR
bypass valve 42 is in the bypass position (shown as dashed line 43
in FIG. 1).
[0118] Step 526: Engine Cooling Through the Transmission.
[0119] If the monitored transmission oil temperature is below the
calibrated extreme transmission temperature while the monitored
engine water temperature is greater than the calibrated extreme
engine temperature, then there is excess cooling capacity through
the transmission 14. Excess heat from the engine 12 may be
transferred from the engine 12 to the transmission oil circuit 28
and the transmission radiator 34.
[0120] Step 528: Valve Set to Transmission Position.
[0121] The method 200 includes setting the two-way valve 26 to the
transmission position, such that the transmission radiator 34 is in
heat-exchange communication with the engine 12. Heat is transferred
from the engine 12 to the engine water circuit 22 and through the
central heat exchanger 36 to the transmission oil circuit 28.
[0122] If the temperature of the transmission oil circuit 28 rises
above the level necessary to actuate the transmission thermostat 44
to the radiator position (shown as dashed line 45 in FIG. 1). Once
the transmission thermostat 44 allows flow through the transmission
radiator 34, the excess heat transferred from the engine 12 is
dissipated through the transmission radiator 34. By setting the
two-way valve 26 to the transmission position, this configuration
of the EGHR system 10 allows excess heat from the engine 12 to be
dissipated through the transmission 14 and the transmission
radiator 34.
[0123] Therefore, in certain conditions, the EGHR systems 10 may be
placed into engine-warming, engine-cooling, transmission-warming,
or transmission-cooling modes. The vehicle cabin may also be warmed
through the heater core 30. Operation of the EGHR system 10 in the
various modes is controlled by selection of the position of the
two-way valve 26 based upon monitored or determined temperatures of
the ambient air, the engine 12, or the transmission 14.
[0124] Step 530: No Excess Cooling Capacity.
[0125] If the monitored engine water temperature is greater than
the calibrated extreme engine temperature and the monitored
transmission oil temperature is also greater than the calibrated
extreme transmission temperature, there is no excess cooling
capacity available through the transmission 14 or transmission
radiator 34.
[0126] Step 532: Valve Set to Engine Position.
[0127] The method then sets the two-way valve 26 to the engine
position, such that the transmission radiator 34 is not in
heat-exchange communication with the engine 12. Therefore, the EGHR
system 10 is configured to only transfer heat to the transmission
14 when it is below the calibrated extreme transmission
temperature. When both the engine 12 and the transmission 14 are
above their respective extreme temperatures, the engine radiator 32
and the transmission radiator 34 are used to dissipate heat.
[0128] The detailed description and the drawings or figures are
supportive and descriptive of the invention, but the scope of the
invention is defined solely by the claims. While some of the best
modes and other embodiments for carrying out the claimed invention
have been described in detail, various alternative designs and
embodiments exist for practicing the invention defined in the
appended claims.
* * * * *