U.S. patent application number 11/297299 was filed with the patent office on 2007-06-14 for apparatus and method for comparing the fuel consumption of an alternative fuel vehicle with that of a traditionally fueled comparison vehicle.
Invention is credited to Kevin S. Kidston, Richard A. Marsh, Paul E. Reinke, Jonathan R. Schwarz, Carlene M. Sienkiewicz.
Application Number | 20070135988 11/297299 |
Document ID | / |
Family ID | 38140494 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070135988 |
Kind Code |
A1 |
Kidston; Kevin S. ; et
al. |
June 14, 2007 |
APPARATUS AND METHOD FOR COMPARING THE FUEL CONSUMPTION OF AN
ALTERNATIVE FUEL VEHICLE WITH THAT OF A TRADITIONALLY FUELED
COMPARISON VEHICLE
Abstract
A fuel savings informational system is provided for
implementation on an alternative fuel vehicle the operation of
which may be characterized by a first plurality of fixed parameters
and a second plurality of variable parameters. The system compares
the fuel consumption of the alternative fuel vehicle to that of a
virtual comparison vehicle characterized by a third plurality of
fixed parameters, and comprises a plurality of sensors for
monitoring the second plurality and a processor coupled thereto.
The processor is configured to recall the first and third
pluralities, capture data corresponding to the second plurality,
and determine the fuel consumption of the alternative fuel vehicle
from the second plurality. The processor is further configured to
estimate the fuel consumption of the comparison vehicle from the
first, second, and third pluralities, and compare the fuel
consumption of the alternative fuel vehicle to the estimated fuel
consumption of the comparison vehicle.
Inventors: |
Kidston; Kevin S.; (New
Hudson, MI) ; Marsh; Richard A.; (Beverly Hills,
MI) ; Reinke; Paul E.; (Rochester Hills, MI) ;
Schwarz; Jonathan R.; (Oakland Township, MI) ;
Sienkiewicz; Carlene M.; (Brighton, MI) |
Correspondence
Address: |
GENERAL MOTORS CORPORATION;LEGAL STAFF
MAIL CODE 482-C23-B21
P O BOX 300
DETROIT
MI
48265-3000
US
|
Family ID: |
38140494 |
Appl. No.: |
11/297299 |
Filed: |
December 8, 2005 |
Current U.S.
Class: |
701/102 ;
340/439; 701/103; 701/115; 701/22 |
Current CPC
Class: |
B60R 16/0232 20130101;
G07C 5/08 20130101 |
Class at
Publication: |
701/102 ;
701/103; 701/115; 701/022; 340/439 |
International
Class: |
G06F 19/00 20060101
G06F019/00; B60Q 1/00 20060101 B60Q001/00 |
Claims
1. A fuel savings informational system for implementation on an
alternative fuel vehicle the operation of which may be
characterized by a first plurality of fixed parameters and a second
plurality of variable parameters, the informational system for
comparing the fuel consumption of the alternative fuel vehicle to
that of a virtual comparison vehicle characterized by a third
plurality of fixed parameters, the system comprising: a plurality
of sensors for monitoring the second plurality of variable
parameters; and a processor coupled to said plurality of sensors,
said processor configured to (i) recall the first and third
pluralities of fixed parameters; (ii) capture data corresponding to
the second plurality of variable parameters; (iii) determine the
fuel consumption of the alternative fuel vehicle from the second
plurality of variable parameters; (iv) estimate the fuel
consumption of the comparison vehicle from the second plurality of
variable parameters and from the first and third pluralities of
fixed parameters; and (v) compare the fuel consumption of the
alternative fuel vehicle to the estimated fuel consumption of the
comparison vehicle.
2. A fuel savings informational system according to claim 1 further
comprising a display coupled to said processor for displaying the
results of the fuel consumption comparison.
3. A fuel savings informational system according to claim 2 wherein
the alternative fuel vehicle and the comparison vehicle each have
an axle and where the first plurality of fixed parameters includes
a first axle ratio and the third plurality of fixed parameters
includes a second axle ratio.
4. A fuel savings informational system according to claim 2 wherein
the alternative fuel vehicle and the comparison vehicle have first
and second wheels, respectively, and where the first plurality of
fixed parameters includes the rolling radius of the first wheel and
the third plurality of fixed parameters includes the rolling radius
of the second wheel.
5. A fuel savings informational system according to claim 2 wherein
the alternative fuel vehicle includes a wheel coupled to said
plurality of sensors and wherein the second plurality of variable
parameters comprises wheel speed and wheel torque.
6. A fuel savings informational system according to claim 5 wherein
the alternative fuel vehicle further includes an accelerator pedal
coupled to said plurality of sensors and wherein the second
plurality of variable parameters further comprises vehicular speed,
vehicular acceleration, and pedal position.
7. A fuel savings informational system according to claim 2 wherein
said processor is further configured to display the instantaneous
fuel consumption rate of the alternative fuel vehicle on said
display.
8. A fuel savings informational system according to claim 2 wherein
the alternative fuel vehicle has an engine coupled to said
plurality of sensors, and wherein the second plurality of variable
parameters includes engine speed and torque model output.
9. A fuel savings informational system according to claim 2 wherein
the alternative fuel vehicle includes an engine having a
predetermined number of cylinders, said engine coupled to said
plurality of sensors, and wherein the second plurality of variable
parameters comprises cylinder count, injector pulse width, and
engine speed.
10. A fuel savings information system according to claim 2 wherein
said processor is configured to estimate the fuel consumption of
the comparison vehicle via a three dimensional look-up table
associating fuel consumption with engine speed and engine torque of
the alternative fuel vehicle.
11. A fuel savings informational system for implementation on a
hybrid vehicle for comparing the fuel consumption of the hybrid
vehicle to that of a virtual comparison vehicle, the operation of
the hybrid vehicle being characterized by a plurality of variable
operational parameters, the hybrid vehicle having a first
predetermined axle ratio and a first predetermined tire rolling
radii and the comparison vehicle having a second predetermined axle
ratio and a second predetermined tire rolling radii, the system
comprising: a display deployed on the hybrid vehicle; a plurality
of sensors for monitoring the plurality of variable operational
parameters; and a processor coupled to said display and to said
plurality of sensors, said processor configured to (i) recall the
first and second axle ratios and the first and second tire rolling
radii; (ii) capture data corresponding to the plurality of variable
operational parameters; (iii) determine the fuel consumption of the
hybrid vehicle from a first subset of the plurality of variable
operational parameters; (iv) estimate the fuel consumption of the
comparison vehicle from a second subset of the plurality of
variable operational parameters, from the first and second axle
ratios, and from the first and second tire rolling radii; (v)
compare the fuel consumption of the hybrid vehicle to the estimated
fuel consumption of the comparison vehicle; and (vi) display the
results of the comparison on said display.
12. A fuel savings informational system according to claim 11
wherein the alternative fuel vehicle includes a wheel and an
accelerator pedal coupled to said plurality of sensors, and wherein
the plurality of variable operational parameters comprises wheel
speed, wheel torque, vehicular speed, vehicular acceleration, and
pedal position.
13. A fuel savings informational system according to claim 11
wherein said processor is further configured to display the
instantaneous fuel consumption rate of the alternative fuel vehicle
on said display.
14. A method for informing a driver of a hybrid vehicle of the
difference between the fuel consumption rate of a virtual
comparison vehicle and the fuel consumption rate of a hybrid
vehicle that includes a display, a plurality of sensors for
measuring a plurality of variable operational parameters relating
to the driving conditions experienced by the hybrid vehicle, and a
processor for recalling a plurality of fixed parameters describing
physical aspects of the hybrid vehicle and the comparison vehicle,
the method comprising: recalling the plurality of fixed parameters;
capturing data corresponding to the plurality of variable
operational parameters; determining hybrid vehicle fuel consumption
rate from the plurality of variable operational parameters;
estimating comparison vehicle fuel consumption rate from the
plurality of variable operational parameters and the plurality of
fixed parameters; comparing hybrid vehicle fuel consumption rate to
comparison vehicle fuel consumption rate; and displaying the
results of the comparison on the display.
15. The method according to claim 14 wherein the step of recalling
comprises recalling tire rolling radii and axle ratios for the
hybrid vehicle and for the comparison vehicle.
16. The method according to claim 14 wherein the hybrid vehicle
includes a wheel and an accelerator pedal and the step of
estimating comprises determining the comparison vehicle fuel
consumption rate from pedal position, vehicular acceleration,
vehicular speed, wheel torque, wheel speed, tire rolling radii, and
axle ratios.
17. The method according to claim 14 wherein the step of displaying
further comprises displaying the instantaneous fuel consumption
rate of the hybrid vehicle on the display.
18. The method according to claim 16 wherein the step of estimating
comprises determining (i) the comparison vehicle deceleration gear
ratio from the pedal position and from the vehicular speed when the
acceleration of the hybrid vehicle is less than zero, and (ii) the
comparison vehicle acceleration gear ratio from the pedal position
and the vehicular speed when the acceleration of the hybrid vehicle
is greater than zero.
19. The method according to claim 16 wherein the step of estimating
comprises (i) calculating the torque converter slip speed when the
torque converter clutch of the virtual comparison vehicle is
unlocked, and (ii) assuming a predetermined torque converter slip
speed when the torque converter clutch of the virtual comparison
vehicle is locked.
20. The method according to claim 16 wherein the step of estimating
comprises assigning a predetermined engine speed to the engine of
the comparison vehicle when the speed of the hybrid vehicle is
substantially zero.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to a fuel savings
display system for use in an alternative fuel vehicle (e.g., a
hybrid vehicle) and, more particularly, to an apparatus and method
for comparing the fuel consumption of an alternative fuel vehicle
with that of a traditionally fueled comparison vehicle.
BACKGROUND OF THE INVENTION
[0002] Since the industrial revolution, society has been reliant on
fossil fuels as its foremost energy source. It is common knowledge
that fossil fuels are in limited supply and that the combustion of
fossil fuels releases environmental pollutants (e.g., carbon
monoxide). Petroleum, which currently supplies approximately 40% of
the planet's energy, has overtaken coal as the most commonly
consumed fossil fuel. One of petroleum's major uses is the
production of gasoline, which drives the internal combustion
engines of the more than 530 million gasoline-powered cars
currently in use throughout the world. In contrast, a much smaller
number of automobiles in existence today utilize alternative
fuels.
[0003] Hybrid electric vehicles improve gas mileage by combining a
battery-powered electric motor/generator with a highly efficient
heat engine, typically an internal combustion engine. In some of
these hybrid or mild-hybrid power train systems, an electric
motor-generator system replaces the conventional starter motor and
the alternator. When the hybrid vehicle is decelerating or is
stopped, the fuel flow to the gasoline-powered engine is shut-off
to improve fuel economy. The motor-generator system of the hybrid
vehicle is implemented to enable this fuel shut-off feature with
substantially no effect on drivability.
[0004] Owners of hybrid automobiles have expressed a desire that
they be provided with data regarding short term and long term fuel
savings. Considering this, it should be appreciated that it would
be desirable to provide a fuel usage and savings informational
system for use on an alternative fuel vehicle that determines the
vehicle's fuel consumption and compares it to the quantity of fuel
that would be consumed by an analogous, exclusively
gasoline-powered vehicle under similar driving conditions. It
should further be appreciated that it would be desirable for such a
fuel informational system to provide accurate data regarding the
vehicle's instantaneous fuel usage that a driver may utilize to
learn how to operate the vehicle in a more fuel efficient manner.
Furthermore, other desirable features and functions of the present
invention will become apparent from the subsequent detailed
description of the invention and the appended claims, taken in
conjunction with the accompanying drawings and this background of
the invention.
SUMMARY OF THE INVENTION
[0005] A fuel savings informational system is provided for use on
an alternative fuel vehicle the operation of which may be
characterized by a first plurality of fixed parameters and a second
plurality of variable parameters. The informational system compares
the fuel consumption of the alternative fuel vehicle to that of a
virtual comparison vehicle characterized by a third plurality of
fixed parameters, and comprises a plurality of sensors for
monitoring the second plurality of variable parameters and a
processor coupled to the plurality of sensors. The processor is
configured to recall the first and third pluralities of fixed
parameters, capture data corresponding to the second plurality of
variable parameters, and determine the fuel consumption of the
alternative fuel vehicle from the second plurality of variable
parameters. The processor is further configured to estimate the
fuel consumption of the comparison vehicle from the second
plurality of variable parameters and from the first and third
pluralities of fixed parameters, and compare the fuel consumption
of the alternative fuel vehicle to the estimated fuel consumption
of the comparison vehicle.
[0006] A method for informing a driver of a hybrid vehicle of the
difference between the fuel consumption rate of a virtual
comparison vehicle and the fuel consumption rate of a hybrid
vehicle is also provided. The hybrid vehicle includes a display, a
plurality of sensors for measuring a plurality of variable
operational parameters relating to the driving conditions
experienced by the hybrid vehicle, and a processor for recalling a
plurality of fixed parameters describing physical aspects of the
hybrid vehicle and the comparison vehicle. The method comprises
recalling the plurality of fixed parameters, capturing data
corresponding to the plurality of variable operational parameters,
and determining hybrid vehicle fuel consumption rate from the
plurality of variable operational parameters. The comparison
vehicle fuel consumption rate is estimated from the plurality of
variable operational parameters and the plurality of fixed
parameters, the hybrid vehicle fuel consumption rate is compared to
comparison vehicle fuel consumption rate. Lastly, the results of
the comparison are displayed on the display.
DESCRIPTION OF THE DRAWINGS
[0007] The present invention will hereinafter be described in
conjunction with the following figures, wherein like reference
numerals denote like elements, and:
[0008] FIG. 1 is a functional block diagram of a vehicular system
suitable for carrying out the inventive fuel usage comparison
process;
[0009] FIG. 2 is a flowchart illustrating a first, generalized
embodiment of the inventive fuel usage comparison process;
[0010] FIG. 3 is a flowchart illustrating a second, more detailed
embodiment of the inventive fuel usage comparison process; and
[0011] FIGS. 4 and 5 are flowcharts illustrating an exemplary
method for comparing vehicle fuel usage suitable for use in
conjunction with the process illustrated in FIG. 3.
DESCRIPTION OF AN EXEMPLARY EMBODIMENT
[0012] The following detailed description of the invention is
merely exemplary in nature and is not intended to limit the scope,
applicability, or configuration of the invention in any way.
Rather, the following description provides a convenient
illustration for implementing exemplary embodiments of the
invention. Various changes to the described embodiments may be made
in the function and arrangement of the elements described herein
without departing from the scope of the invention.
[0013] FIG. 1 is a functional block diagram of a vehicular system
100 for comparing the fuel consumption of an alternative fuel
vehicle with that of a traditionally fueled comparison vehicle. The
system comprises a central Communications Gateway Module (CGM) 102
that is coupled to three Local Area Networks (LANs): Low Speed LAN
104, High Speed LAN 106, and Power-Train Expansion LAN 108. As is
well known in the automotive industry, LANs 104, 106, and 108 may
each comprise a plurality of components; however, only some of
these components are shown and discussed below to ensure clarity.
As can be seen in FIG. 1, Low Speed LAN 104 comprises an Electronic
Climate Control (ECC) 110, an Air Conditioning Control Module
(ACCM) 112, and an Instrument Control Panel (ICP) 114. High Speed
LAN 106 comprises an Engine Control Module (ECM) 116, an Electronic
Brake Control Module (EBCM) 118, and a Transmission Control Module
(TCM) 120. Lastly, Power-Train Expansion LAN 108 comprises an
Accessory Control Module (ACM) 122 and a Hybrid Control Processor
(HCP) 124. As will be more fully described below, each of these
components may communicate with CGM 102 on their respective LANs as
the inventive fuel usage comparison process is performed.
[0014] System 100 may be deployed on an alternative fuel vehicle
(referred to as the host vehicle below) and may determine and
display fuel usage information regarding various aspects of the
host vehicle's fuel usage. Some or all of these aspects may be
compared to fuel usage information determined for a virtual model
of a similar vehicle that is exclusively powered by gasoline
(referred to as the comparison vehicle below). More specifically, a
processor or processors associated with system 100 (e.g., employed
in CGM 102) may determine fuel usage information (e.g., fuel
consumption rate) for both the host vehicle and the comparison
vehicle utilizing driving parameters experienced by the host
vehicle and reported by various components on the Local Area
Networks. After establishing the desired fuel usage statistics, a
processor or module (e.g., CGM 102) may display the statistics on a
suitable display in the manner described below.
[0015] FIG. 2 is a flowchart illustrating a first, generalized
embodiment of a fuel usage comparison process 126 that may be
carried out by system 100. The process begins by recalling constant
or fixed parameters that describe physical aspects of the host
vehicle and/or the comparison vehicle (e.g., the tire rolling radii
of the host vehicle and the comparison vehicle, etc.) and capturing
variable operational parameters experienced by the host vehicle
during operation (e.g., vehicular speed, engine RPM, etc.) as
illustrated in FIG. 2 at 128 and 130, respectively. From these
parameters, fuel usage information for the host vehicle may be
determined by the vehicle's processors in accordance with a know
technique (132). As indicated in FIG. 2 at 134, fuel usage
information for the comparison vehicle may be determined by
execution of a comparison vehicle fuel usage process 150 discussed
below in conjunction with FIGS. 4 and 5. Very generally, such a
comparison vehicle fuel usage process may determine the fuel
consumption rate of the comparison vehicle by establishing the
current rotational speed and torque of the host vehicle's wheels
and, subsequently, determining the torque and speed (in RPM) at
which the engine of the comparison vehicle must operate to generate
to produce the same rotational speed and torque at the comparison
vehicle's wheels. After fuel usage information has been determined
for the host vehicle and the comparison vehicle, fuel usage
comparison data (e.g., the host vehicle's fuel savings relative to
the comparison vehicle for a given period of time) may then be
determined (136) and displayed (138) on a display associated with
ICP 114, a navigational system, a driver control interface, or the
like. Finally, as indicated in FIG. 2 at 140, process 126 may be
repeated.
[0016] FIG. 3 is a flowchart illustrating a second, more detailed
embodiment of a fuel usage comparison process 142 that may be
carried out by system 100. As indicated at 144, process 142 may
begin by recalling fixed vehicular parameters; i.e., the tire
rolling radii and axle ratios for both the host vehicle and the
comparison vehicle. Next, a group of variable parameters may be
gathered indicative of the current driving conditions under which
the host vehicle is operating (146). These parameters may include:
(1) engine speed/RPM, (2) torque model output, (3) vehicular speed,
(4) vehicular acceleration, (5) pedal position, (6) cylinder count,
(7) injector pulse width, and (8) wheel torque. The current values
of these parameters are reported over the Local Area Networks by
the components discussed above in conjunction with FIG. 1. As an
example, the following components may determine and report the
following host vehicle parameters. ECM 116 may report: (a) engine
speed, which may be determined by the rotational frequency of the
host vehicle's crank shaft; (b) the torque model output, which may
be determined from the axle torque reported to ECM 116 by HCP 124;
(c) the speed of the host vehicle; (d) cylinder count; and (e)
injector pulse width. EBCM 118 may report: (a) vehicle
acceleration, which may be determined from the rotational frequency
of the host vehicle's wheels, (b) accelerator pedal position, and
(c) wheel torque.
[0017] After capturing the current status of each of the variable
operational parameters, the process may determine the host
vehicle's fuel consumption rate by reference to a known three
dimensional look-up table that compares fuel rate to engine speed
and torque, as indicated at 148 in FIG. 3. Alternatively, the host
vehicle's fuel consumption rate be expressed as a function of
cylinder count, pulse width, and engine speed. If desired, the host
vehicle's fuel consumption rate may be adjusted by further
considering other relevant factors (e.g., engine coolant
temperature, transmission oil temperature, elapsed time since
start, pedal position, etc.). Also, after the variable parameters
have been captured, the fuel consumption rate for the comparison
vehicle may determined by execution of a suitable comparison
vehicle fuel usage process (150), such as the exemplary process
describe in detail below in conjunction with FIGS. 4 and 5. When
the host vehicle's fuel rate and the comparison vehicle's fuel rate
have been determined, they may be compared in a number of ways. As
suggested in FIG. 3 at 152, for example, the instantaneous fuel
savings (IFS), the updated cumulative fuel savings (CFS), and the
fuel efficiency percentage (FEP) may be determined via equations
(1), (2), and (3) below: IFS = FR comp . - FR host t ( 1 ) ##EQU1##
where FR is fuel rate and t is elapsed time, and
CFS.sub.new=IFS+CFS.sub.old (2) where CFS.sub.new is the updated
cumulative fuel savings and CFS.sub.old is the prior cumulative
fuel savings (i.e., the cumulative fuel savings that does not
account for the fuel used by the host vehicle during the latest
iteration of the fuel comparison process). FEP = 100 .times. ( FR
comp . - FR host FR comp ) ( 3 ) ##EQU2##
[0018] After establishing the desired fuel comparison metrics, the
metrics may be displayed along with host vehicle fuel usage
information (e.g., the host vehicle's fuel consumption rate) on a
suitable display associated with, for example, ICP 114, a driver
control interface, or a navigational system that is integrated with
the host vehicle's radio. The exemplary fuel usage comparison
process is then repeated to continually update the displayed fuel
usage information as indicated in FIG. 3 at 156.
[0019] As mentioned previously, the comparison vehicle's fuel rate
may be determined by the performance of a suitable comparison
vehicle fuel usage process (see step 150 in FIG. 3). This process
may estimate the comparison vehicle's fuel consumption rate by
determining the torque and speed/RPM at which the comparison
vehicle's engine must operate to generate the torque and rotational
speed at its wheels matching that generated at the host vehicle's
wheels. An exemplary embodiment of such a process (i.e., process
150) is illustrated in FIGS. 4 and 5.
[0020] As indicated at 160 in FIG. 4, process 150 begins by
determining the wheel speed of the host vehicle by way of the
following equation: WS host = K .function. ( VS host 2 .times. .pi.
.times. TRR host ) ( 4 ) ##EQU3## where WS is wheel speed, VS is
vehicular speed, TRR is tire rolling radius (multiplied by 2.pi. in
EQ. 4 to convert to the tire rolling circumference), and K is a
constant representing distance and time conversions (for English
units in miles and feet K may be approximately 5280/60, and for
metric units in kilometers and meters K may be approximately
1000/60). In EQ. (4) and hereafter, it should be noted that the
subscripts "host" and "comp." indicate that the metric to which the
subscript is attached describes the host vehicle and the comparison
vehicle, respectively.
[0021] After determining the host vehicle's wheel speed, the
comparison vehicle's wheel speed may be determined as indicated at
step 162 in accordance with the following equation: WS comp . = WS
host .function. ( TRR comp . TRR host ) ( 5 ) ##EQU4## However, it
should be noted that, although wheel speed is calculated in the
exemplary embodiment, in other embodiments of the invention wheel
speed may instead be monitored by a suitable sensor and simply
reported to a processor, such as processor 150. Next, the process
determines the comparison vehicle's transmission output speed (TOS)
in the following manner (164 in FIG. 4):
TOS.sub.comp.=WS.sub.comp..times.AR.sub.comp. (6) where AR is axle
ratio.
[0022] The comparison vehicle's transmission output speed may be
utilized to help determine the comparison vehicle's transmission
input speed; however, first the appropriate gear ratio must be
determined. Thus, as indicated in FIG. 4 at 166, if the host
vehicle is accelerating, the corresponding acceleration gear ratio
is established via a three dimensional look-up table associating
gear ratio with the host vehicle's pedal position and speed in the
well-known manner (170). Conversely, if the host vehicle is not
accelerating (i.e., if the host vehicle is coasting or
decelerating), the comparison vehicle's deceleration gear ratio is
established with a similar three dimensional look-up table (168).
After being established, the comparison vehicle's gear ratio may be
multiplied by the transmission output speed to determine the
transmission input speed (TIS) of the comparison vehicle (172 in
FIG. 4) as indicated by EQ. 7 below:
TIS.sub.comp.=TOS.sub.comp..times.GR.sub.comp. (7) where GR is the
gear ratio.
[0023] Next, as indicated in FIG. 4 at 174, the transmission output
torque (TOT) may be determined in accordance with EQ. 8: TOT comp .
= WT host AR comp . ( 8 ) ##EQU5## where WT is wheel torque.
[0024] Although EQ. 8 will provide a fairly accurate estimate of
the comparison vehicle's transmission output torque, it should be
noted that, if the tire rolling radius for the host vehicle and for
the virtual comparison vehicle differ, especially by a large
amount, a more accurate estimate of the comparison vehicle's
transmission output torque may be obtained using equations 8A-8D: F
host = WT host TRR host ( 8 .times. A ) F comp . = F host
.function. ( M comp . M host ) ( 8 .times. B ) WT comp . = F comp .
.times. TRR comp . ( 8 .times. C ) TOT comp . = WT comp . AR comp .
( 8 .times. D ) ##EQU6## where F.sub.host is the drive force
exhibited on the host vehicle, F.sub.comp. is the drive force
exhibited on the comparison vehicle, M.sub.comp. is the comparison
vehicle's mass, and M.sub.host is the host vehicle's mass.
[0025] After the comparison vehicle's transmission output torque is
known, the transmission input torque (TIT) may subsequently be
determined in accordance with EQ. 9 (shown at 176 in FIG. 4): TIT
comp . = TOT comp . GR comp . ( 9 ) ##EQU7##
[0026] After establishing the comparison vehicle's transmission
input torque, the process may move to step 178 illustrated in FIG.
5 to determine if the comparison vehicle's torque converter clutch
is locked by way of a known four dimensional look-up table that
compares torque converter clutch to the host vehicle's pedal
position, the host vehicle's vehicular speed, and the comparison
vehicle's gear ratio. If it is determined that the torque converter
clutch is not locked (determined at 179 in FIG. 5), then the torque
converter slip speed (SS) may be determined via the following
empirical equation (180 in FIG. 5):
SS.sub.comp.=(-0.76).times.(TIT.sub.comp.).sup.2+14.3.times.TIT.sub.comp.-
+500 (10) where transmission input torque is in Newton-meters and
slip speed is in revolutions per minute.
[0027] If, instead, the torque converter clutch is determined to be
locked at 180, the process assumes torque converter slip speed to
be a controlled slip of 40 RPM as indicated in FIG. 5 at 182. After
determining the slip speed, the comparison vehicle's engine speed
(ES) may be determined as follows (184 in FIG. 5):
ES.sub.comp.=TIS.sub.comp.+SS.sub.comp. (11)
[0028] After determining the comparison vehicle's engine speed, the
process next determines the comparison vehicle's engine torque to
ultimately establish the comparison vehicle's fuel consumption
rate. If the host vehicle is a hybrid vehicle, the process
preferably accounts for the rotational frequency of the comparison
vehicle's engine at idle when the hybrid host is stopped and its
engine is shut off. If the host vehicle is at a standstill
(determined in FIG. 5 at 186), this may be done by assuming the
comparison vehicle's engine speed to be 525 RPM as indicated in
FIG. 5 at 188. If, however, the host vehicle is moving (again,
determined in FIG. 5 at 186), the process determines the comparison
vehicle's transmission torque converter speed ratio (SR) in the
following manner (indicated in FIG. 5 at 192): SR comp . = TIS comp
. ES comp . ( 12 ) ##EQU8##
[0029] Next, the torque converter torque multiplier (TM) is
established via a conventional two dimensional look-up table that
associates the torque multiplier with the torque converter speed
ratio (indicated in FIG. 5 at 194). After the torque multiplier is
known, the process determines the comparison vehicle's engine
torque (ET) in accordance with EQ. 13 below (196 in FIG. 5): ET
comp . = TIT comp . TM comp . .times. ( 13 ) ##EQU9##
[0030] It may be desirable to adjust the engine torque determined
from EQ. 13 to account for the load placed on the host vehicle's
engine by the accessories (e.g., the vehicle's air conditioning)
currently operating in the host vehicle as reported on Power-Train
Expansion LAN 108 by ACM 122. As indicated at 198 in FIG. 5, this
may be done by simply adding the accessory load to the comparison
vehicle's engine torque determined in EQ. 13.
[0031] Now that the comparison engine's speed and torque based on
the host vehicle's operating conditions are known, the comparison
vehicle's fuel consumption rate may be determined as indicated in
FIG. 5 at 200. This may be done by reference to a three dimensional
look-up table wherein fuel rate is associated with engine speed and
engine torque in the well-known manner. After the comparison
vehicle's fuel rate has been determined, process 150 is complete.
It should thus be appreciated that the process has now utilized
fixed parameters describing physical aspects of the host vehicle
and the comparison vehicle and variable parameters relating to the
operational conditions of the host vehicle to determine comparison
vehicle fuel usage data (e.g., the comparison vehicle's fuel
consumption rate), which may then be compared to host vehicle fuel
usage data in the manner described above in conjunction with EQs.
1-3 and steps 152 and 154 of FIG. 3.
[0032] On a closing note, it may be desirable to further improve
accuracy in determining the comparison vehicle's fuel consumption
rate by considering component efficiencies, including, but not
limited to, axle efficiencies, transmission efficiencies, and
torque converter efficiencies. Axle efficiency, for example, may be
accounted for by multiplying the comparison's vehicle axle ratio
(AR.sub.comp.) by a value representing the comparison vehicle's
axle efficiency (e.g., approximately 0.97 for a rear drive
differential) in EQ. 8 above, providing that the host vehicle is
moving. In a similar fashion, transmission efficiency, which may
include transmission gear losses and hydraulic losses, may be
accounted for by multiplying the comparison's gear ratio
(GR.sub.comp.) by a value representing the comparison vehicle's
transmission efficiency (e.g., a number between 0 and 1 determined
by, for example, a conventional look-up table) in EQ. 9 above.
Lastly, torque converter efficiency may be accounted for by
multiplying the comparison vehicle's torque converter multiplier
(TM.sub.comp.) by a value representing torque converter efficiency
in EQ. 13 above. However, it may desirable to only compensate for
torque converter efficiencies when the torque converter is
unlocked; when locked, the torque converter is very efficient and
thus torque converter efficiencies have little effect on the
comparison vehicle's fuel consumption rate.
[0033] It should thus be appreciated that there has been provided a
fuel usage and savings informational system for use on an
alternative fuel vehicle that determines the vehicle's fuel
consumption and compares it to the estimated fuel usages of an
analogous, exclusively gasoline-powered vehicle operating under
similar driving conditions. It should further be appreciated that
there has been provided a system that indicates the host vehicle's
instantaneous fuel usage, which a driver may utilize to learn how
to operate the vehicle in a fuel efficient manner.
[0034] While a limited number of exemplary embodiments have been
presented in the foregoing detailed description, it should be
appreciated that a vast number of variations exist. It should also
be appreciated that the exemplary embodiments are only examples,
and are not intended to limit the scope, applicability, or
configuration of the invention in any way. Rather, the foregoing
detailed description will provide those skilled in the art with a
convenient road map for implementing the exemplary embodiments.
Various changes can be made in the function and arrangement of
elements without departing from the scope of the invention as set
forth in the appended claims and the legal equivalents thereof.
* * * * *