U.S. patent application number 15/452398 was filed with the patent office on 2018-09-13 for methods and systems for improving electric energy storage device durability for a stop/start vehicle.
The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Alexander O`Connor Gibson, Thomas G. Leone, Kenneth James Miller, Eric Michael Rademacher.
Application Number | 20180258898 15/452398 |
Document ID | / |
Family ID | 63258553 |
Filed Date | 2018-09-13 |
United States Patent
Application |
20180258898 |
Kind Code |
A1 |
Leone; Thomas G. ; et
al. |
September 13, 2018 |
METHODS AND SYSTEMS FOR IMPROVING ELECTRIC ENERGY STORAGE DEVICE
DURABILITY FOR A STOP/START VEHICLE
Abstract
Systems and methods for restarting an engine are presented. In
one example, an engine may be automatically stopped and started in
response to thresholds that may be adjusted as a distance traveled
by the vehicle increases. The thresholds may be adjusted responsive
to useful life consumed of devices that may participate in
automatic engine starting and stopping.
Inventors: |
Leone; Thomas G.;
(Ypsilanti, MI) ; Miller; Kenneth James; (Canton,
MI) ; Rademacher; Eric Michael; (Beverly Hills,
MI) ; Gibson; Alexander O`Connor; (Ann Arbor,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Family ID: |
63258553 |
Appl. No.: |
15/452398 |
Filed: |
March 7, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02N 11/0825 20130101;
F02N 2011/0888 20130101; F02N 11/0862 20130101; B60W 30/188
20130101; F02N 2200/14 20130101; Y02T 10/48 20130101; F02N 11/084
20130101; F02N 2011/0885 20130101; F02N 11/0833 20130101; F02N
2200/061 20130101; Y02T 10/40 20130101 |
International
Class: |
F02N 11/08 20060101
F02N011/08; B60W 30/188 20060101 B60W030/188 |
Claims
1. A vehicle operating method, comprising: estimating an amount of
electric energy storage device useful life consumed via a
controller; adjusting automatic engine stop/start thresholds in
response to the amount of electric energy storage device useful
life consumed; and starting or stopping the engine in response to
the automatic engine start/stop thresholds via the controller.
2. The method of claim 1, where the automatic engine stop/start
thresholds include a minimum electric energy storage device state
of charge threshold for permitting automatic engine stopping
responsive to a percentage of useful electric energy storage device
life consumed.
3. The method of claim 1, where the automatic engine stop/start
thresholds include a maximum accessory load threshold for
permitting automatic engine stopping responsive to a percentage of
useful electric energy storage device life consumed.
4. The method of claim 1, where the automatic engine stop/start
thresholds include a maximum vehicle speed for permitting automatic
engine stopping responsive to a percentage of useful electric
energy storage device life consumed.
5. The method of claim 1, where the automatic engine stop/start
thresholds include a minimum electric energy storage device state
of charge threshold for automatic engine starting responsive to a
percentage of useful electric energy storage device life
consumed.
6. The method of claim 5, where the automatic engine stop/start
thresholds include a maximum accessory load threshold for automatic
engine starting responsive to a percentage of useful electric
energy storage device life consumed.
7. The method of claim 1, where the automatic engine stop/start
thresholds include a maximum vehicle speed for automatic engine
stopping responsive to a percentage of useful electric energy
storage device life consumed.
8. A vehicle operating method, comprising: estimating an amount of
useful life consumed of a device via a controller, the amount of
useful life consumed a summation of individual estimates; adjusting
automatic engine stop/start thresholds in response to the amount of
useful life consumed; and automatically starting or stopping the
engine in response to the automatic engine start/stop thresholds
via the controller.
9. The method of claim 8, where the summation of individual
estimates includes estimates of DC/DC converter life consumed.
10. The method of claim 8, where the summation of individual
estimates includes estimates of electrical energy storage device
life consumed.
11. The method of claim 8, where the summation of individual
estimates includes estimates of power relay life consumed or
inverter system life consumed.
12. The method of claim 8, where the automatic engine stop/start
thresholds include a minimum electric energy storage device state
of charge threshold for permitting automatic engine stopping
responsive to a percentage of useful electric energy storage device
life consumed.
13. The method of claim 8, where the automatic engine stop/start
thresholds include a maximum accessory load threshold for
permitting automatic engine stopping responsive to a percentage of
useful electric energy storage device life consumed.
14. The method of claim 8, where the automatic engine stop/start
thresholds include a maximum vehicle speed for permitting automatic
engine stopping responsive to a percentage of useful electric
energy storage device life consumed.
15. A vehicle system, comprising: an engine including a device, the
device participating in automatically starting and stopping the
engine; and a controller including non-transitory instructions
executable to adjust automatic engine stop/start thresholds in
response to an amount of useful life consumed of the device, and to
automatically start or stop the engine in response to the automatic
engine start/stop thresholds.
16. The vehicle system of claim 15, where the device is a DC/DC
converter.
17. The vehicle system of claim 15, where the device is an electric
energy storage device.
18. The vehicle system of claim 15, where the device is a power
relay.
19. The vehicle system of claim 15, where the automatic engine
stop/start thresholds include a minimum electric energy storage
device state of charge threshold.
20. The vehicle system of claim 15, where automatic engine
stop/start thresholds include a maximum accessory load threshold.
Description
FIELD
[0001] The present description relates to a system and methods for
improving durability of components for a vehicle with an engine
that may be automatically stopped and started. The methods may be
particularly useful for extending component life while still
enabling automatic engine starting and stopping.
BACKGROUND AND SUMMARY
[0002] A vehicle may include an engine that may be automatically
stopped and restarted without a driver of the vehicle specifically
requesting an engine stop and start. The engine may be
automatically stopped and restarted to conserve fuel. The engine
may be stopped when the driver of the vehicle is not requesting
torque while the vehicle is moving or while the vehicle is stopped.
Before the engine is automatically stopped, a controller may
require that certain conditions be met. For example, the controller
may require that electric energy storage device state of charge is
higher than a threshold, an electrical load applied to the vehicle
electrical system is less than a threshold, electric energy storage
device temperature is less than a threshold, and driver demand
torque is less than a threshold. If the conditions are met, the
engine may be automatically stopped and then restarted to conserve
fuel. However, some vehicles may be more frequently automatically
stopped and started as compared to other vehicles. Vehicle
components used to automatically stop and start the engine may be
constructed to provide the engine start/stop functionality over a
predetermined vehicle travel distance even when the engine is
frequently stopped and started; however, the cost of producing such
vehicle components may be prohibitive. Therefore, it would be
desirable to provide a way of permitting automatic engine stopping
and starting over a predetermined travel distance with reasonable
vehicle component cost.
[0003] The inventors herein have recognized the above-mentioned
issues and have developed a vehicle operating method, comprising:
estimating an amount of electric energy storage device useful life
consumed via a controller; adjusting automatic engine stop/start
thresholds in response to the amount of electric energy storage
device useful life consumed; and starting or stopping the engine in
response to the automatic engine start/stop thresholds via the
controller.
[0004] By adjusting automatic engine stopping and starting
thresholds in response to an amount of electric energy storage
device useful life consumed, it may be possible to decrease
frequency and rigorousness of automatic engine stops and starts so
that devices may operate over their expected life cycle. Further,
automatic engine stopping and starting may still be permitted so
that the vehicle's fuel efficiency may be relatively high. In some
examples, if the percent of useful life consumed of the device is
less than a threshold, the automatic engine stopping and starting
thresholds may be returned to base values. In this way, automatic
engine stopping and stopping entry conditions may be made more or
less rigorous depending on how the engine has been previously
stopped and started so that component life may meet expectations
while delivering desirable fuel economy.
[0005] The present description may provide several advantages. For
example, the approach may allow engine components to reach a
desired life span. In addition, the approach may allow component
life spans to be met without having to make the components suitable
for extreme duty cycle conditions. Further, the approach may be
applicable to more than one type of component.
[0006] The above advantages and other advantages, and features of
the present description will be readily apparent from the following
Detailed Description when taken alone or in connection with the
accompanying drawings.
[0007] It should be understood that the summary above is provided
to introduce in simplified form a selection of concepts that are
further described in the detailed description. It is not meant to
identify key or essential features of the claimed subject matter,
the scope of which is defined uniquely by the claims that follow
the detailed description. Furthermore, the claimed subject matter
is not limited to implementations that solve any disadvantages
noted above or in any part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The advantages described herein will be more fully
understood by reading an example of an embodiment, referred to
herein as the Detailed Description, when taken alone or with
reference to the drawings, where:
[0009] FIG. 1 is a schematic diagram of an engine;
[0010] FIG. 2 is a prophetic example plot illustrating useful
electric energy storage device life versus vehicle travel
distance;
[0011] FIG. 3 shows plots of an example sequence for extending
stop/start vehicle component life; and
[0012] FIG. 4 is a flowchart showing one example method for
extending stop/start vehicle component life.
DETAILED DESCRIPTION
[0013] The present description is related to extending life of
vehicle components that participate in automatic engine stopping
and starting. The engine may be automatically stopped and started
based on vehicle conditions. FIG. 1 shows an example engine that
may be automatically stopped and started. FIG. 2 shows an example
curve that describes percentage of electric energy storage device
life consumed versus vehicle travel distance. A prophetic sequence
for extending vehicle component life according to the method of
FIG. 4 is shown in FIG. 3. Finally, a method for providing desired
component life over a predetermined vehicle travel distance is
shown in FIG. 4.
[0014] Referring to FIG. 1, internal combustion engine 10,
comprising a plurality of cylinders, one cylinder of which is shown
in FIG. 1, is controlled by electronic engine controller 12. Engine
10 includes combustion chamber 30 and cylinder walls 32 with piston
36 positioned therein and connected to crankshaft 40. Flywheel 97
and ring gear 99 are coupled to crankshaft 40. Starter 96 includes
pinion shaft 98 and pinion gear 95. Pinion shaft 98 may selectively
advance pinion gear 95 to engage ring gear 99. Starter 96 may be
directly mounted to the front of the engine or the rear of the
engine. In some examples, starter 96 may selectively supply torque
to crankshaft 40 via a belt or chain. In one example, starter 96 is
in a base state when not engaged to the engine crankshaft.
Combustion chamber 30 is shown communicating with intake manifold
44 and exhaust manifold 48 via respective intake valve 52 and
exhaust valve 54. Each intake and exhaust valve may be operated by
an intake cam 51 and an exhaust cam 53. The position of intake cam
51 may be determined by intake cam sensor 55. The position of
exhaust cam 53 may be determined by exhaust cam sensor 57. Intake
cam 51 and exhaust cam 53 may be moved relative to crankshaft 40
via variable intake cam actuator 59 and variable exhaust cam
actuator 60.
[0015] Starter 96 may receive electrical power from electric energy
storage device 155 (e.g., battery or ultra-capacitor) via power
relay or inverter system 115. Power relay/inverter 115 may close to
allow current to flow from electric energy storage device 155 to
starter 96 in response to a signal from controller 12. Power relay
115 may open to interrupt current flow from electric energy storage
device 155 to starter 96 in response to a signal from controller
12. DC/DC converter 135 may provide power to electric energy
storage device 155 from alternator or integrated starter generator
119. Crankshaft 40 may rotate alternator or integrated starter
generator 119 to produce electrical power to charge electric energy
storage device 155.
[0016] Fuel injector 66 is shown positioned to inject fuel directly
into cylinder intake port 49, which is known to those skilled in
the art as port fuel injection. Fuel injector 66 delivers liquid
fuel in proportion to the pulse width of signal from controller 12.
Fuel is delivered to fuel injector 66 by a fuel system (not shown)
including a fuel tank, fuel pump, and fuel rail (not shown). In
addition, intake manifold 44 is shown communicating with optional
electronic throttle 62 which adjusts a position of throttle plate
64 to control air flow from air intake 42 to intake manifold 44. In
some examples, throttle 62 and throttle plate 64 may be positioned
between intake valve 52 and intake manifold 44 such that throttle
62 is a port throttle.
[0017] Distributorless ignition system 88 provides an ignition
spark to combustion chamber 30 via spark plug 92 in response to
controller 12. Universal Exhaust Gas Oxygen (UEGO) sensor 126 is
shown coupled to exhaust manifold 48 upstream of catalytic
converter 70. Alternatively, a two-state exhaust gas oxygen sensor
may be substituted for UEGO sensor 126.
[0018] Converter 70 can include multiple catalyst bricks, in one
example. In another example, multiple emission control devices,
each with multiple bricks, can be used. Converter 70 can be a
three-way type catalyst in one example.
[0019] Controller 12 is shown in FIG. 1 as a conventional
microcomputer including: microprocessor unit 102, input/output
ports 104, read-only memory 106 (e.g., non-transitory memory),
random access memory 108, keep alive memory 110, and a conventional
data bus. Controller 12 is shown receiving various signals from
sensors coupled to engine 10, in addition to those signals
previously discussed, including: engine coolant temperature (ECT)
from temperature sensor 112 coupled to cooling sleeve 114; a
position sensor 134 coupled to an accelerator pedal 130 for sensing
force applied by foot 132; a measurement of engine manifold
pressure (MAP) from pressure sensor 122 coupled to intake manifold
44; an engine position sensor from a Hall effect sensor 118 sensing
crankshaft 40 position; a measurement of air mass entering the
engine from sensor 120; and a measurement of throttle position from
sensor 58. Barometric pressure may also be sensed (sensor not
shown) for processing by controller 12. In a preferred aspect of
the present description, engine position sensor 118 produces a
predetermined number of equally spaced pulses every revolution of
the crankshaft from which engine speed (RPM) can be determined.
[0020] During operation, each cylinder within engine 10 typically
undergoes a four stroke cycle: the cycle includes the intake
stroke, compression stroke, expansion stroke, and exhaust stroke.
During the intake stroke, generally, the exhaust valve 54 closes
and intake valve 52 opens. Air is introduced into combustion
chamber 30 via intake manifold 44, and piston 36 moves to the
bottom of the cylinder so as to increase the volume within
combustion chamber 30. The position at which piston 36 is near the
bottom of the cylinder and at the end of its stroke (e.g. when
combustion chamber 30 is at its largest volume) is typically
referred to by those of skill in the art as bottom dead center
(BDC). During the compression stroke, intake valve 52 and exhaust
valve 54 are closed. Piston 36 moves toward the cylinder head so as
to compress the air within combustion chamber 30. The point at
which piston 36 is at the end of its stroke and closest to the
cylinder head (e.g. when combustion chamber 30 is at its smallest
volume) is typically referred to by those of skill in the art as
top dead center (TDC). In a process hereinafter referred to as
injection, fuel is introduced into the combustion chamber. In a
process hereinafter referred to as ignition, the injected fuel is
ignited by known ignition means such as spark plug 92, resulting in
combustion. During the expansion stroke, the expanding gases push
piston 36 back to BDC. Crankshaft 40 converts piston movement into
a rotational torque of the rotary shaft. Finally, during the
exhaust stroke, the exhaust valve 54 opens to release the combusted
air-fuel mixture to exhaust manifold 48 and the piston returns to
TDC. Note that the above is shown merely as an example, and that
intake and exhaust valve opening and/or closing timings may vary,
such as to provide positive or negative valve overlap, late intake
valve closing, or various other examples.
[0021] The system of FIG. 1 provides for a vehicle system,
comprising: an engine including a device, the device participating
in automatically starting and stopping the engine; and a controller
including non-transitory instructions executable to adjust
automatic engine stop/start thresholds in response to an amount of
useful life consumed of the device, and to automatically start or
stop the engine in response to the automatic engine start/stop
thresholds. The vehicle system includes where the device is one or
more of an inverter system, rectifier system, of a DC/DC converter.
The vehicle system includes where the device is an electric energy
storage device. The vehicle system includes where the device is a
capacitor or ultra-capacitor. The vehicle system includes where the
device is a power relay. The vehicle system includes where the
automatic engine stop/start thresholds include a minimum electric
energy storage device state of charge threshold. The vehicle system
includes where the automatic engine stop/start thresholds include a
maximum electric energy storage device temperature. The vehicle
system includes where the automatic engine stop/start thresholds
include a maximum vehicle speed threshold. The vehicle system
includes where automatic engine stop/start thresholds include a
maximum accessory load threshold.
[0022] Referring now to FIG. 2, a prophetic example plot
illustrating an estimated of percentage useful electric energy
storage device life consumed versus vehicle travel distance is
shown. The relationship shown in FIG. 2 may be incorporated into
the system of FIG. 1 and the method of FIG. 3.
[0023] The plot includes a vertical axis representing percent of
useful electric energy storage device life consumed and the
vertical axis starts at a value of zero and ends at a value of one
hundred. The horizontal axis represents a distance traveled by the
vehicle and the actual distance traveled by the vehicle increases
from the left side of the figure to the right side of the figure.
The distance traveled at the vertical axis is zero.
[0024] Curve 202 shows an example relationship of percentage of
useful electric energy storage device life consumed and distance
traveled by the vehicle. In this example, the electric energy
storage device is expected to be degraded when the percentage of
useful electric energy storage device life consumed is one hundred
percent. The distance traveled by the vehicle is expected to be the
value at B when one hundred percent of useful electric energy
storage device life is consumed. Thus, the electric energy storage
device may be expected to operate for the distance corresponding to
B. Similarly, half the useful life of the electric energy storage
device, or fifty percent of useful electric energy storage device
life consumed, may be expected to be consumed when the vehicle has
traveled the distance corresponding to A. Curve 202 may be
empirically determined from a variety of vehicle and electric
energy storage device operating conditions as discussed in further
detail with regard to method 400.
[0025] The percent of useful electric energy storage device life
consumed may be estimated from curve 202 by determining an actual
total distance traveled by the vehicle and indexing a table or
function via the actual total distance traveled by the vehicle. The
point on curve 202 where the distance traveled by the vehicle
intersects curve 202 corresponds to a single value of useful
electric energy storage device life consumed. In this way,
percentage of useful electric energy storage device life consumed
may be estimated via knowing the distance traveled by the vehicle.
Data values that form curve 202 may be empirically determined and
stored to controller memory.
[0026] Although FIG. 2 discloses a relationship between useful
electric energy storage device life consumed and distance traveled
by a vehicle, similar relationships between other components of a
start/stop vehicle and distance traveled by a vehicle may be
provided. For example, another curve or plot may describe a
relationship between percent of useful life of a electric power
relay consumed versus distance traveled by the vehicle. In this
way, expected useful life consumed of the various vehicle devices
associated with a stop/start vehicle may be estimated.
[0027] Referring now to FIG. 3, an example sequence illustrating
modifications to an automatic engine stop/start procedure according
to the method of FIG. 4 is shown. The operating sequence of FIG. 3
may be provided via the system of FIG. 1 executing instructions
according to the method of FIG. 4 that are stored in non-transitory
memory. Vertical markers D1-D3 represent times of particular
interest during the sequence. All plots in FIG. 3 are aligned with
regard to vehicle travel distance. Note that a small space may
exist between traces to improve visibility even though the traces
are described as being equal at some conditions.
[0028] The first plot from the top of FIG. 3 is a plot of time
versus distance traveled by a vehicle. The vertical axis represents
time and time increases in the direction of the vertical axis
arrow. The horizontal axis represents distance traveled by the
vehicle and the distance traveled increases in the direction of the
horizontal axis arrow. Curve 302 indicates the relationship between
time and distance traveled by the vehicle.
[0029] The second plot from the top of FIG. 3 is a plot of
percentage of electric energy storage device life consumed versus
distance traveled by a vehicle. The vertical axis represents
percentage of electric energy storage device life consumed and
percentage of electric energy storage device life consumed
increases in the direction of the vertical axis arrow. The percent
of electric energy storage device life consumed is zero when the
electric energy storage device is new and percent of electric
energy storage device life consumed is one hundred percent when the
electric energy storage device is degraded. The horizontal axis
represents distance traveled by the vehicle and the distance
traveled increases in the direction of the horizontal axis arrow.
Solid line curve 304 represents a predetermined expected
relationship between percent of electric energy storage device life
consumed and distance traveled by the vehicle and it may be
referred to as a percentage of electric energy storage device
useful life consumed threshold. Dotted line curve 306 represents a
relationship between percentage of electric energy storage device
life consumed and distance traveled by the vehicle that is
determined in real-time as the vehicle is operated and travels an
increasing amount of distance. Curve 306 may be referred to as the
estimated percent of electric energy storage device useful life
consumed.
[0030] The third plot from the top of FIG. 3 is a plot of minimum
electric energy storage device state of charge (SOC) for automatic
engine stopping versus distance traveled by a vehicle. The minimum
electric energy storage device state of charge is a threshold level
of electric energy storage device charge below which the engine is
not automatically stopped. For example, if the minimum electric
energy storage device SOC is 40% and the actual or measured
electric energy storage device SOC is 35%, the engine will not be
automatically stopped and started. However, if the actual or
measured SOC is 65% then the engine may be automatically stopped
and started. The vertical axis represents minimum electric energy
storage device SOC for automatic engine stopping and minimum
electric energy storage device SOC for automatic engine stopping
increases in the direction of the vertical axis arrow. The
horizontal axis represents distance traveled by the vehicle and the
distance traveled increases in the direction of the horizontal axis
arrow.
[0031] Solid line curve 312 represents a relationship between
minimum electric energy storage device SOC for automatic engine
stopping and distance traveled by the vehicle for an electric
energy storage device exhibiting a low amount of degradation. Curve
312 may also be referred to as minimum electric energy storage
device SOC threshold for automatic engine stopping for an electric
energy storage device exhibiting a low amount of degradation or a
lower electric energy storage device SOC threshold for automatic
engine stopping for an electric energy storage device exhibiting a
low amount of degradation. Solid line curve 308 represents a
relationship between minimum electric energy storage device SOC for
automatic engine stopping and distance traveled by the vehicle for
an electric energy storage device that is older and exhibiting a
higher level of degradation. Curve 308 may also be referred to as
minimum electric energy storage device SOC threshold for automatic
engine stopping for an electric energy storage device exhibiting a
higher amount of degradation or a lower electric energy storage
device SOC threshold for automatic engine stopping for an electric
energy storage device exhibiting a higher amount of degradation.
Dashed line curve 310 represents a minimum electric energy storage
device SOC threshold for permitting automatic engine stopping
responsive to the percentage of useful electric energy storage
device life consumed at the present distance traveled by the
vehicle. Operating the electric energy storage device at state of
charge values below 310 may degrade the electric energy storage
device in an undesirable way so automatic engine starting and
stopping may be prohibited when electric energy storage device
state of charge is below curve 310.
[0032] The fourth plot from the top of FIG. 3 is a plot of maximum
accessory load for permitting automatic engine stopping versus
distance traveled by a vehicle. The maximum accessory load for
permitting automatic engine stopping is a threshold level of
electrical load above which the engine is not automatically
stopped. For example, if the maximum accessory load is 5 amperes
and the actual or measured accessory load is 6 amperes, the engine
will not be automatically stopped and started. However, if the
actual or measured accessory load is 3 amperes then the engine may
be automatically stopped and started. The vertical axis represents
maximum accessory load for permitting automatic engine stopping and
maximum accessory load for permitting automatic engine stopping
increases in the direction of the vertical axis arrow. The
horizontal axis represents distance traveled by the vehicle and the
distance traveled increases in the direction of the horizontal axis
arrow.
[0033] Solid line curve 314 represents a relationship between
maximum accessory load for permitting automatic engine stopping and
distance traveled by the vehicle for a new electric energy storage
device. Curve 314 may also be referred to as maximum accessory load
threshold for automatic engine stopping for an electric energy
storage device exhibiting a low amount of degradation or an upper
accessory load threshold for automatic engine stopping for an
electric energy storage device exhibiting a low amount of
degradation. Solid line curve 316 represents a relationship between
maximum accessory load for permitting automatic engine stopping and
distance traveled by the vehicle for an electric energy storage
device that is older and partially degraded. Curve 316 may also be
referred to as maximum accessory load threshold for automatic
engine stopping for an electric energy storage device exhibiting a
higher amount of degradation or an upper accessory load threshold
for automatic engine stopping for an electric energy storage device
exhibiting a higher amount of degradation. Dashed line curve 318
represents a maximum accessory load threshold for permitting
automatic engine stopping responsive to the percentage of electric
energy storage device life consumed at the present distance
traveled by the vehicle. Operating the electric energy storage
device when accessory load is above curve 318 may degrade the
electric energy storage device in an undesirable way (e.g., higher
current draw than is desired) so automatic engine starting may be
prohibited when accessory load is above temperatures of curve
318.
[0034] The fifth plot from the top of FIG. 3 is a plot of maximum
vehicle speed for permitting automatic engine stopping versus
distance traveled by a vehicle. The maximum vehicle speed for
permitting automatic engine stopping is a threshold level of
vehicle speed above which the engine is not automatically stopped.
For example, if the maximum vehicle speed for permitting automatic
engine stopping is 35 Kph and the actual or measured vehicle speed
40 Kph, the engine will not be automatically stopped and started.
However, if the actual or measured vehicle speed is 30 Kph then the
engine may be automatically stopped and started. The vertical axis
represents maximum vehicle speed for permitting automatic engine
stopping and maximum vehicle speed for permitting automatic engine
stopping increases in the direction of the vertical axis arrow. The
horizontal axis represents distance traveled by the vehicle and the
distance traveled increases in the direction of the horizontal axis
arrow.
[0035] Solid line curve 320 represents a relationship between
maximum vehicle speed for permitting automatic engine stopping and
distance traveled by the vehicle for a new electric energy storage
device. Curve 320 may also be referred to as the maximum vehicle
speed threshold for permitting automatic engine stopping for an
electric energy storage device exhibiting a lower amount of
degradation or an upper vehicle speed threshold for permitting
automatic engine stopping for an electric energy storage device
exhibiting a lower amount of degradation. Solid line curve 322
represents a relationship between maximum vehicle speed for
permitting automatic engine stopping and distance traveled by the
vehicle for an electric energy storage device that is older and
partially degraded. Curve 322 may also be referred to as maximum
vehicle speed threshold for permitting automatic engine stopping
for an electric energy storage device exhibiting a higher amount of
degradation or an upper vehicle speed threshold for permitting
automatic engine stopping for an electric energy storage device
exhibiting a higher amount of degradation. Dashed line curve 324
represents a maximum vehicle speed for permitting automatic engine
stopping responsive to the percentage of electric energy storage
device life consumed at the present distance traveled by the
vehicle. Operating the electric energy storage device when vehicle
speed is above curve 324 may degrade the electric energy storage
device in an undesirable way (e.g., higher current draw than is
desired) so automatic engine starting may be prohibited when
vehicle speed is above temperatures of curve 324.
[0036] At travel distance D0, the amount of time in the first plot
is zero and the estimated percent of electric energy storage device
life consumed (curve 306) is less than the predetermined percent of
electric energy storage device life consumed threshold (curve 304).
The minimum electric energy storage device SOC for automatic engine
stopping (curve 310) is adjusted to a low level that is equal to
the threshold electric energy storage device SOC for automatic
engine stopping for an electric energy storage device exhibiting a
low amount of degradation (curve 312). Therefore, the engine is
permitted to automatically stop and start when electric energy
storage device SOC is greater than the level of curve 312 because
the electric energy storage device is exhibiting a low amount of
degradation. The maximum accessory load for permitting automatic
engine stopping (curve 318) is adjusted to a higher level that is
equal to the maximum accessory load threshold for automatic engine
stopping for an electric energy storage device exhibiting a low
amount of degradation (curve 314). Consequently, the engine is
permitted to automatically stop and start when accessory load is at
a higher level because the electric energy storage device is
exhibiting a low amount of degradation. The maximum vehicle speed
for permitting automatic engine stopping (curve 324) is adjusted to
a higher level that is equal to the maximum vehicle speed threshold
for permitting automatic engine stopping for an electric energy
storage device exhibiting a lower amount of degradation (curve
320). As such, the engine is permitted to automatically stop and
start when vehicle speed is higher because the electric energy
storage device is exhibiting a low amount of degradation.
[0037] Between distance D0 and distance D1, the amount of time
increases and the distance traveled by the vehicle increases. The
estimated percent of electric energy storage device life consumed
(curve 306) increases but it remains less than the predetermined
percent of electric energy storage device life consumed threshold
(curve 304). Further, the expected relationship between percent of
electric energy storage device life consumed and distance traveled
by the vehicle (curve 304) increases to show that expected electric
energy storage device degradation increases with distance traveled
by the vehicle. The estimated percent of electric energy storage
device life consumed (curve 306) increases but it remains less than
the expected percentage of electric energy storage device life
consumed threshold (curve 304).
[0038] The minimum electric energy storage device SOC for automatic
engine stopping for an electric energy storage device exhibiting a
low amount of degradation (curve 312) increases to show that the
minimum electric energy storage device state of charge for
automatic engine stopping with a small amount of electric energy
storage device degradation increases as distance traveled by the
vehicle increases. Likewise, minimum electric energy storage device
SOC for automatic engine stopping for an electric energy storage
device exhibiting a higher amount of degradation (curve 308)
increases to show that minimum electric energy storage device state
of charge for automatic engine stopping with a larger amount of
electric energy storage device degradation increases as distance
traveled by the vehicle increases. The minimum electric energy
storage device SOC for automatic engine stopping responsive to
percentage of electric energy storage device life consumed at the
present distance traveled by the vehicle (curve 310) follows and
stays equal to the minimum electric energy storage device SOC for
automatic engine stopping for an electric energy storage device
exhibiting a low amount of degradation (curve 312).
[0039] The maximum accessory load for permitting automatic engine
stopping for an electric energy storage device exhibiting a low
amount of degradation (curve 314) decreases to show that the
maximum accessory load for automatic engine stopping with a small
amount of electric energy storage device degradation decreases as
distance traveled by the vehicle increases. Likewise, maximum
accessory load for permitting automatic engine stopping for an
electric energy storage device exhibiting a higher amount of
degradation (curve 316) decreases to show that the maximum
accessory load for automatic engine stopping with a larger amount
of electric energy storage device degradation decreases as distance
traveled by the vehicle increases. The maximum accessory load for
permitting automatic engine stopping responsive to percentage of
electric energy storage device life consumed at the present
distance traveled by the vehicle (curve 318) follows and stays
equal to the maximum electric energy storage device SOC for
automatic engine stopping for an electric energy storage device
exhibiting a low amount of degradation (curve 318).
[0040] The maximum vehicle speed for permitting automatic engine
stopping for an electric energy storage device exhibiting a low
amount of degradation (curve 320) decreases to show that the
maximum vehicle speed for automatic engine stopping with a small
amount of electric energy storage device degradation decreases as
distance traveled by the vehicle increases. Likewise, maximum
vehicle speed for permitting automatic engine stopping for an
electric energy storage device exhibiting a higher amount of
degradation (curve 322) decreases to show that the maximum vehicle
speed for automatic engine stopping with a larger amount of
electric energy storage device degradation decreases as distance
traveled by the vehicle increases. The maximum vehicle speed for
permitting automatic engine stopping responsive to percentage of
electric energy storage device life consumed at the present
distance traveled by the vehicle (curve 324) follows and stays
equal to the maximum vehicle speed for automatic engine stopping
for an electric energy storage device exhibiting a low amount of
degradation (curve 320).
[0041] At distance D1, the amount of time in the first plot and the
distance traveled continue to increase. The estimated percent of
electric energy storage device life consumed (curve 306) increases
to a value greater than the predetermined percent of electric
energy storage device life consumed threshold (curve 304).
Consequently, the minimum electric energy storage device SOC for
automatic engine stopping is adjusted to a higher level that is
equal to the minimum electric energy storage device SOC threshold
for automatic engine stopping for an electric energy storage device
exhibiting a higher amount of degradation (curve 308). Therefore,
the engine is permitted to automatically stop and start when
electric energy storage device SOC is at a higher level so that the
electric energy storage device may be exposed to less rigorous
conditions to extend electric energy storage device life. The
maximum accessory load for permitting automatic engine stopping is
adjusted to a lower level that is equal to the maximum accessory
load threshold for automatic engine stopping for an electric energy
storage device exhibiting a higher amount of degradation (curve
316). As a result, the engine is permitted to automatically stop
and start when accessory load is at a lower level so that
conditions that may accelerate electric energy storage device
degradation to a level greater than desired may be avoided. The
maximum vehicle speed for permitting automatic engine stopping
(curve 324) is adjusted to a lower level that is equal to the
maximum vehicle speed threshold for permitting automatic engine
stopping for an electric energy storage device exhibiting a higher
amount of degradation (curve 322). This change permits the engine
to automatically stop and start when vehicle speed is lower;
thereby, potentially reducing the actual total number of automatic
engine stops and start to reduce the possibility of electric energy
storage device degradation exceeding a desired level.
[0042] Between distance D1 and distance D2, the amount of time
increases and the distance traveled by the vehicle increases. The
estimated percent of electric energy storage device life consumed
(curve 306) remains above the predetermined percent of electric
energy storage device life consumed (curve 304), but the measured
percentage of electric energy storage device life consumed
increases at a slow rate. In addition, the expected relationship
between percent of electric energy storage device life consumed and
distance traveled by the vehicle (curve 304) continues to
increase.
[0043] The minimum electric energy storage device SOC for automatic
engine stopping for an electric energy storage device exhibiting a
low amount of degradation (curve 312) increases and the minimum
electric energy storage device SOC for automatic engine stopping
for an electric energy storage device exhibiting a higher amount of
degradation (curve 308) also increases with distance traveled. The
minimum electric energy storage device SOC for automatic engine
stopping responsive to percentage of electric energy storage device
life consumed at the present distance traveled by the vehicle
(curve 310) follows and stays equal to the minimum electric energy
storage device SOC threshold for automatic engine stopping for an
electric energy storage device exhibiting a higher amount of
degradation (curve 308). Adjusting the minimum electric energy
storage device SOC for automatic engine stopping responsive to
electric energy storage device life consumed in this way may extend
electric energy storage device life and reduce a rate of electric
energy storage device degradation.
[0044] The maximum accessory load for permitting automatic engine
stopping for an electric energy storage device exhibiting a low
amount of degradation (curve 314) decreases and the maximum
accessory load for permitting automatic engine stopping for an
electric energy storage device exhibiting a higher amount of
degradation (curve 316) also decreases. The maximum accessory load
for permitting automatic engine stopping responsive to percentage
of electric energy storage device life consumed at the present
distance traveled by the vehicle (curve 318) follows and stays
equal to the maximum accessory load threshold for automatic engine
stopping for an electric energy storage device exhibiting a higher
amount of degradation (curve 316) to extend electric energy storage
device life. The maximum vehicle speed for permitting automatic
engine stopping responsive to percentage of electric energy storage
device life consumed at the present distance traveled by the
vehicle (curve 324) follows and stays equal to the maximum vehicle
speed threshold for permitting automatic engine stopping for an
electric energy storage device exhibiting a higher amount of
degradation (curve 322).
[0045] At distance D2, the amount of time in the first plot and the
distance traveled continue to increase. The estimated percent of
electric energy storage device life (curve 306) consumed falls
below the predetermined percent of electric energy storage device
life consumed threshold (curve 304). Therefore, the minimum
electric energy storage device SOC for automatic engine stopping is
adjusted to a lower level that is equal to the minimum electric
energy storage device SOC threshold for automatic engine stopping
for an electric energy storage device exhibiting a low amount of
degradation (curve 312). This allows the engine to be automatically
stopped and started when electric energy storage device SOC is at a
lower level so that vehicle fuel economy may be increased. The
maximum accessory load for permitting automatic engine stopping is
also adjusted to a higher level that is equal to the maximum
accessory load threshold for automatic engine stopping for an
electric energy storage device exhibiting a low amount of
degradation (curve 314). This action allows the engine to be
automatically stopped and started when accessory load is at a
higher level so that vehicle fuel economy may be increased. The
maximum vehicle speed for permitting automatic engine stopping is
adjusted to a higher level that is equal to the maximum vehicle
speed threshold for permitting automatic engine stopping for an
electric energy storage device exhibiting a lower amount of
degradation (curve 320) so that vehicle fuel economy may be
increased.
[0046] Between distance D2 and distance D3, the amount of time
increases and the distance traveled by the vehicle increases. The
estimated percent of electric energy storage device life consumed
(curve 306) remains below the predetermined percent of electric
energy storage device life consumed threshold (curve 304) so the
electric energy storage device is estimated to exhibit a lower
level of degradation. Additionally, the percentage of electric
energy storage device useful life consumed threshold (curve 304)
continues to increase.
[0047] The minimum electric energy storage device SOC for automatic
engine stopping for an electric energy storage device exhibiting a
low amount of degradation (curve 312) continues to increase and the
minimum electric energy storage device SOC for automatic engine
stopping for an electric energy storage device exhibiting a higher
amount of degradation (curve 308) continues to increase with
distance traveled. The minimum electric energy storage device SOC
for automatic engine stopping responsive to percentage of electric
energy storage device life consumed at the present distance
traveled by the vehicle (curve 310) follows and stays equal to the
minimum electric energy storage device SOC threshold for automatic
engine stopping for an electric energy storage device exhibiting a
low amount of degradation (curve 312).
[0048] The maximum accessory load threshold for permitting
automatic engine stopping for an electric energy storage device
exhibiting a low amount of degradation (curve 314) continues to
decrease and the maximum accessory load threshold for permitting
automatic engine stopping for an electric energy storage device
exhibiting a higher amount of degradation (curve 316) also
continues to decrease. The maximum accessory load for permitting
automatic engine stopping responsive to percentage of electric
energy storage device life consumed at the present distance
traveled by the vehicle (curve 318) follows and stays equal to the
maximum accessory load threshold for automatic engine stopping for
an electric energy storage device exhibiting a low amount of
degradation (curve 314) to improve vehicle fuel economy. The
maximum vehicle speed for permitting automatic engine stopping
responsive to percentage of electric energy storage device life
consumed at the present distance traveled by the vehicle (curve
324) follows and stays equal to the maximum vehicle speed threshold
for permitting automatic engine stopping for an electric energy
storage device exhibiting a lower amount of degradation (curve
320).
[0049] At distance D3, the amount of time in the first plot and the
distance traveled continue to increase. The measured percent of
electric energy storage device life consumed increases to a value
greater than the predetermined percent of electric energy storage
device life consumed (curve 304) for a second time. Therefore, the
minimum electric energy storage device SOC for automatic engine
stopping (curve 310) is adjusted to a higher level that is equal to
the minimum electric energy storage device SOC threshold for
automatic engine stopping for an electric energy storage device
exhibiting a higher amount of degradation (curve 308). This action
allows the engine to automatically stop and start when electric
energy storage device SOC is at a higher level so that the electric
energy storage device may be exposed to less rigorous conditions to
extend electric energy storage device life. The maximum accessory
load for permitting automatic engine stopping (curve 318) is also
adjusted to a lower level that is equal to the maximum accessory
load threshold for automatic engine stopping for an electric energy
storage device exhibiting a higher amount of degradation (curve
316). In this way, the engine is permitted to automatically stop
and start when accessory load is at a lower level, instead of a
higher level, so that conditions that may accelerate electric
energy storage device degradation to a level greater than desired
may be avoided. The maximum vehicle speed for permitting automatic
engine stopping (curve 324) is adjusted to a lower level that is
equal to the maximum vehicle speed threshold for permitting
automatic engine stopping for an electric energy storage device
exhibiting a higher amount of degradation (curve 322) so that the
engine may only automatically stop and start when vehicle speed is
lower.
[0050] In this way, thresholds that define whether or not an engine
may be automatically stopped and started may be adjusted to
compensate for component life consumed. This may help to ensure
that a vehicle may travel a desired distance before degradation of
selected vehicle components may be expected.
[0051] Referring now to FIG. 4, a flow chart describing a method
for controlling degradation of start/stop vehicle components is
shown. The method of FIG. 4 may be incorporated into and may
cooperate with the system of FIG. 1 to provide the operating
sequence shown in FIG. 3. Further, at least portions of the method
of FIG. 4 may be incorporated as executable instructions stored in
non-transitory memory while other portions of the method may be
performed via a controller transforming operating states of devices
and actuators in the physical world.
[0052] At 402, method 400 estimates a percentage of vehicle
component life that has been consumed. One estimate of component
life consumed is provided for an electric energy storage device
(e.g., a battery or ultra-capacitor). The amount of electric energy
storage device life consumed may be estimated via the following
equation:
ELC=.SIGMA..sub.i.sup.nf.sub.i(.DELTA.SOC,t,E.sub.temp)
where ELC is electric energy storage device life consumed, f is a
function that estimates percentage of electric energy storage
device life consumed during a charging or discharging event (e.g.,
a period of time where the electric energy storage device is
charging or discharging), i is a variable identifying the present
electric energy storage device charge or discharge cycle event
number, .DELTA. SOC is an average rate of change for electric
energy storage device state of charge during the present electric
energy storage device charging or discharging event, t is the
duration of the electric energy storage device charging or
discharging event, and E.sub.temp is average electric energy
storage device temperature during the present electric energy
storage device charging or discharging event. An electric energy
storage device charging event may begin after an electric energy
storage device has finished a discharging cycle and begins to be
charged. The electric energy storage device charging cycle may end
when the electric energy storage device begins to discharge. An
electric energy storage device discharging event may begin after an
electric energy storage device has finished a charging cycle and
begins to discharge. The electric energy storage device discharging
cycle may end when the electric energy storage device begins to
charge. The value of i is incremented for each new charging cycle
and each new discharging cycle. In one example, function f is
outputs empirically determined values of percentage of electric
energy storage device life consumed for an electric energy storage
device charging or discharging cycle responsive to .DELTA. SOC, t,
and E.sub.temp. The parameters .DELTA. SOC, t, and E.sub.temp
provide indications of electric energy storage device performance,
which may be useful to determine electric energy storage device
stress since lower SOC, t, and E.sub.temp may influence stress on
an electric energy storage device. By factoring these parameters
into electric energy storage device life consumption estimation, a
more accurate estimate of electric energy storage device life may
be provided.
[0053] Method 400 may also include an estimate of DC/DC converter
life consumed and an estimate of power relay life consumed. The
amount of DC/DC converter life consumed may be estimated via the
following equation:
DLC=.SIGMA..sub.i.sup.ng.sub.i(.DELTA.I,t,DC.sub.temp)
where DLC is DC/DC converter life consumed, g is a function that
estimates percentage of DC/DC converter life consumed during an
electric energy storage device charging or discharging event (e.g.,
a period of time where the electric energy storage device is
charging or discharging), is a variable identifying the present
electric energy storage device charge or discharge cycle event
number, .DELTA.I is an average rate of change of DC/DC current
input or output during the present electric energy storage device
charging or discharging event, t is the duration of the electric
energy storage device charging or discharging event, and
DC.sub.temp is average DC/DC converter temperature during the
present electric energy storage device charging or discharging
event. In one example, function g is outputs empirically determined
values of percentage of DC/DC converter useful life consumed for an
electric energy storage device charging or discharging cycle
responsive to .DELTA.I, t, and DC.sub.temp. The parameters
.DELTA.I, t, and DC.sub.temp provide indications of DC/DC converter
performance, which may be useful to determine DC/DC converter
stress since lower I, t, and DC.sub.temp may influence stress on
the DC/DC converter. By factoring these parameters into DC/DC
converter life consumption estimation, a more accurate estimate of
electric energy storage device life may be provided.
[0054] The amount of power relay life consumed may be estimated via
the following equation:
PLC=.SIGMA..sub.j.sup.nh.sub.i(.diamond.I,P.sub.temp)
where PLC is power relay life consumed, h is a function that
estimates percentage of power relay life consumed during power
relay operation (e.g., a period of time where the electric energy
storage device is charging or discharging), j is a variable
identifying the present opening or closing event number for the
power relay, .DELTA.I is an average rate of change current flow
through the power relay when the power relay is opened or closed
and P.sub.temp is average power relay temperature during the
present power relay opening or closing event. In one example,
function h is outputs empirically determined values of percentage
of power relay life consumed for a power relay opening or closing
event (e.g., contacts of the power relay close to allow current
flow through the power relay and contacts of the power relay open
to not allow current flow through the power relay). Estimates for
amount of useful life consumed of other components, such as an
invertor, may be estimated in a similar way. Method 400 proceeds to
404.
[0055] At 404, method 400 adjusts the electric energy storage
device useful life consumed threshold (e.g., 304 of FIG. 3), the
DC/DC converter useful life consumed threshold, and the power relay
useful life consumed threshold. In one example, each of the
electric energy storage device useful life consumed threshold, the
DC/DC converter useful life consumed threshold, and the power relay
useful life consumed threshold may be expressed as polynomials. The
coefficients of the respective polynomials may be adjusted
responsive to vehicle operating conditions to increase the
respective useful life consumed thresholds or decrease the useful
life thresholds with respect to distance the vehicle travels. For
example, if the electric energy storage device useful life
threshold is approximated by:
EUL=a+bD+cD.sup.2
where EUL is the percentage of electric energy storage device
useful life consumed, a is a first coefficient, b is a second
coefficient, c is a third coefficient, and D is distance traveled
by the vehicle. Coefficients a, b, and c may be adjusted to
increase EUL for a given D or decrease EUL for the given D. For
example, coefficient a may be a function of ambient temperature,
ambient humidity, and other vehicle operating conditions, and the
state of the vehicle operating conditions may operate to modify
coefficient a. Method 400 proceeds to 406 after adjusting the
electric energy storage device useful life threshold, the DC/DC
converter useful life threshold, and the power relay threshold.
[0056] At 406, method 400 judges if the percentage of actual
electric energy storage device useful life consumed is greater than
the electric energy storage device useful life consumed threshold.
An example visual reference of estimated electric energy storage
device useful life consumed (e.g., 306) and the electric energy
storage device useful life consumed threshold (e.g., 304) is
provided in the second plot from the top of FIG. 3. Further, method
400 may judge if the percentage of actual DC/DC converter useful
life consumed is greater than the DC/DC converter useful life
consumed threshold. Method 400 may also judge if the percentage of
actual power relay useful life consumed is greater than the power
relay useful life consumed threshold. If method 400 judges that the
estimated electric energy storage device useful life consumed is
greater than the electric energy storage device useful life
consumed threshold, the answer is yes and method 400 proceeds to
408. Similarly, if method 400 judges that the estimated DC/DC
converter useful life consumed is greater than the DC/DC converter
useful life consumed threshold, the answer is yes and method 400
proceeds to 408. Further, if method 400 judges that the estimated
power relay useful life consumed is greater than the power relay
useful life consumed threshold, the answer is yes and method 400
proceeds to 408. However, if the estimates of electric energy
storage device useful life consumed, DC/DC converter useful life
consumed, and power relay useful life consumed do not exceed their
respective thresholds, the answer is no and method 400 proceeds to
410.
[0057] At 408, method 400 adjusts entry conditions that permit
automatic engine starting and stopping. An engine may be
automatically started and stopped without a driver requesting
engine start or stop through a dedicated input for engine starting
and stopping (e.g., an ignition switch or key switch). In
particular, an engine may be stopped when driver demand torque as
determined from an accelerator pedal position or an autonomous
vehicle controller output is less than a threshold. However, the
engine may not be permitted to automatically stop and start
responsive to driver demand unless other conditions are also met.
For example, for an automatic engine stop to be permitted, electric
energy storage device SOC must be greater than a minimum electric
energy storage device SOC threshold. Further, for an automatic
engine stop to be permitted, electrical load on the vehicle
electrical system (e.g., electrical power drawn from the electrical
system) must be less than a threshold electrical load. In addition,
for an automatic engine stop to be permitted, vehicle speed may
have to be less than a vehicle speed threshold. The thresholds
against which vehicle operating conditions are compared to before
allowing or rejecting automatic engine stopping and starting may be
referred to as entry conditions for automatically stopping the
engine (e.g., automatically ceasing engine rotation). Similar entry
conditions are provided for automatically starting an engine that
is stopped and not rotating.
[0058] The entry conditions or thresholds may require different
conditions to be met before an engine is automatically stopped or
started as a distance the vehicle travels increases. For example,
as shown in FIG. 3, electric energy storage device SOC may be
compared to a minimum electric energy storage device SOC threshold
to determine if automatic engine stopping is permitted. The minimum
electric energy storage device SOC threshold may increase as a
distance the vehicle travels increases. The minimum electric energy
storage device SOC threshold may be set to a minimum electric
energy storage device SOC threshold above which the engine may be
automatically stopped for an electric energy storage device
exhibiting low degradation (curve 312) or a minimum electric energy
storage device SOC threshold at which the engine may be
automatically stopped for an electric energy storage device
exhibiting higher degradation (curve 308). At 408, method 400 may
require that electric energy storage device SOC be greater than the
minimum electric energy storage device SOC threshold. Method 400
may also require that the minimum electric energy storage device
SOC threshold be equal to an electric energy storage device SOC
threshold for automatic engine stopping for an electric energy
storage device exhibiting a higher amount of degradation (curve
308) when the actual percentage of electric energy storage device
useful life consumed is greater than the expected electric energy
storage device useful life threshold. Method 400 may also require
that the minimum electric energy storage device SOC threshold be
equal to an electric energy storage device SOC threshold for
automatic engine stopping for a DC/DC converter exhibiting higher
degradation when actual percentage of DC/DC converter useful life
consumed is greater than the expected DC/DC converter useful life
threshold. Method 400 may also require that the minimum electric
energy storage device SOC threshold be equal to an electric energy
storage device SOC threshold for automatic engine stopping when a
power relay is exhibiting higher degradation and when actual
percentage of power relay useful life consumed is greater than the
expected power relay useful life threshold. For a particular
distance traveled by the vehicle, the minimum electric energy
storage device SOC threshold for permitting automatic engine
stopping for an electric energy storage device exhibiting higher
degradation is greater than the minimum electric energy storage
device SOC threshold for permitting automatic engine stopping for
an electric energy storage device exhibiting less degradation as
shown in FIG. 3.
[0059] Similarly, electric energy storage device SOC may be
compared to a minimum electric energy storage device SOC threshold
to determine if automatic engine starting is permitted. The minimum
electric energy storage device SOC threshold may increase as a
distance the vehicle travels increases to ensure engine starting.
The minimum electric energy storage device SOC threshold may be set
to a minimum electric energy storage device SOC threshold above
which the engine may be automatically started for an electric
energy storage device exhibiting low degradation or a minimum
electric energy storage device SOC threshold above which the engine
may be automatically started for an electric energy storage device
exhibiting higher degradation. At 408, method 400 may require that
electric energy storage device SOC be greater than the minimum
electric energy storage device SOC threshold. Method 400 may also
require that the minimum SOC threshold be equal to an electric
energy storage device SOC threshold for automatic engine starting
for an electric energy storage device exhibiting higher degradation
when the actual percentage of electric energy storage device useful
life consumed is greater than the expected electric energy storage
device useful life threshold so that a higher confidence level of
engine starting may be provided and so that the possibility of
electric energy storage device degradation may be reduced. Further,
method 400 may require that the electric energy storage device SOC
threshold be equal to the minimum electric energy storage device
SOC threshold for automatic engine starting for a DC/DC converter
exhibiting a higher amount of degradation when actual percentage of
DC/DC converter useful life consumed is greater than the expected
DC/DC converter useful life threshold. Method 400 may also require
that the electric energy storage device SOC threshold be equal to
the minimum electric energy storage device SOC threshold for
automatic engine starting for a power relay exhibiting a higher
amount of degradation when an estimated percentage of power relay
useful life consumed is greater than the expected power relay
useful life threshold. For a particular distance traveled by the
vehicle, minimum electric energy storage device SOC threshold for
permitting automatic engine starting for an electric energy storage
device exhibiting higher degradation is greater than the minimum
electric energy storage device SOC threshold for permitting
automatic engine starting for an electric energy storage device
exhibiting less degradation.
[0060] Accessory load may be compared to a maximum accessory load
(e.g., an electrical load or power consumed by electric consumers
of the vehicle) threshold for permitting automatic engine stopping,
and the maximum accessory load threshold may be decreased as a
distance the vehicle travels increases. Additionally, there may be
a maximum accessory load threshold below which the engine may be
automatically stopped for an electric energy storage device
exhibiting low degradation (curve 314) and a maximum accessory load
threshold below which the engine may be automatically stopped for
an electric energy storage device exhibiting higher degradation
(curve 316). At 408, method 400 may require that the accessory load
be less than the maximum accessory load threshold. Method 400 may
also require that the maximum accessory load threshold be equal to
an accessory load threshold for automatic engine stopping for an
electric energy storage device exhibiting higher degradation (curve
316) when the actual percentage of electric energy storage device
useful life consumed is greater than the expected electric energy
storage device useful life threshold. Method 400 may also require
that the accessory load threshold be equal to the maximum accessory
load threshold for automatic engine stopping for a DC/DC converter
exhibiting higher degradation when the actual percentage of DC/DC
converter useful life consumed is greater than the expected DC/DC
converter useful life threshold. Method 400 may also require that
the accessory load threshold be equal to the maximum accessory load
threshold for automatic engine stopping for a power relay
exhibiting higher degradation (curve 316) when the actual
percentage of power relay useful life consumed is greater than the
expected power relay useful life threshold. The maximum accessory
load threshold for permitting automatic engine stopping for an
electric energy storage device exhibiting higher degradation is
less than the maximum accessory load threshold for permitting
automatic engine stopping for an electric energy storage device
exhibiting less degradation as shown in FIG. 3.
[0061] Accessory load may be compared to a maximum accessory load
threshold for permitting automatic engine starting, and the maximum
accessory load threshold may be decreased as a distance the vehicle
travels increases so that the engine is restarted sooner if
accessory load increases while the engine is stopped. There may
also be a maximum accessory load threshold at which the engine may
be automatically started for an electric energy storage device
exhibiting low degradation and a maximum accessory load threshold
at which the engine may be automatically started for an electric
energy storage device exhibiting higher degradation. At 408, method
400 may require that the maximum accessory load be less than the
maximum accessory load threshold. Method 400 may also require that
the maximum accessory load threshold be equal to a maximum
accessory load for automatic engine starting for an electric energy
storage device exhibiting higher degradation when the actual
percentage of electric energy storage device useful life consumed
is greater than the expected electric energy storage device useful
life threshold. Similarly, method 400 may require that the
accessory load threshold be equal to the maximum accessory load
threshold for automatic engine starting for a DC/DC converter
exhibiting higher degradation when actual percentage of DC/DC
converter useful life consumed is greater than the expected DC/DC
converter useful life threshold. Method 400 may also require that
the accessory load threshold be equal to the maximum accessory load
threshold for automatic engine starting for a power relay
exhibiting higher degradation when actual percentage of power relay
useful life consumed is greater than the expected power relay
useful life threshold. The maximum accessory load threshold for an
electric energy storage device exhibiting higher degradation is
less than the maximum accessory load threshold for an electric
energy storage device exhibiting less degradation.
[0062] The maximum vehicle speed at which an engine may be
automatically be stopped may decrease as a distance the vehicle
travels increases so that the possibility of stopping the engine
may be reduced, thereby reducing possibility of degrading engine
stop/start system components. There may also be a maximum vehicle
speed threshold at which the engine may be automatically stopped
for an electric energy storage device exhibiting low degradation
and a maximum vehicle threshold at which the engine may be
automatically stopped for an electric energy storage device
exhibiting higher degradation. At 408, method 400 may require that
the vehicle speed be less than the maximum vehicle speed threshold.
Method 400 may also require that the maximum vehicle speed
threshold be equal to a maximum vehicle speed threshold for
automatic engine stopping for an electric energy storage device
exhibiting higher degradation when the actual percentage of
electric energy storage device useful life consumed is greater than
the expected electric energy storage device useful life threshold.
Similarly, method 400 may require that the maximum vehicle speed
threshold be equal to the maximum vehicle speed threshold for
automatic engine stopping for a DC/DC converter exhibiting higher
degradation when actual percentage of DC/DC converter useful life
consumed is greater than the expected DC/DC converter useful life
threshold. Method 400 may also require that the maximum vehicle
speed threshold be equal to the maximum vehicle speed threshold for
automatic engine stopping for a power relay exhibiting higher
degradation when actual percentage of power relay useful life
consumed is greater than the expected power relay useful life
threshold. The maximum vehicle speed threshold for an electric
energy storage device exhibiting higher degradation is less than
the maximum vehicle speed threshold for an electric energy storage
device exhibiting less degradation as shown in FIG. 3.
[0063] Alternatively, instead of adjusting the minimum electric
energy storage device SOC for automatic engine stopping from a
threshold for low electric energy storage device degradation to a
minimum electric energy storage device SOC for automatic engine
stopping from a threshold for higher electric energy storage device
degradation, a single threshold for minimum electric energy storage
device SOC for automatic engine stopping may be adjusted to a
higher level (e.g., requiring electric energy storage device SOC to
be a higher level to permit automatic engine stopping) or a lower
level via adjusting coefficients of a polynomial that describes the
minimum electric energy storage device SOC for automatic engine
stopping threshold. Similarly, coefficients of polynomials
describing maximum accessory load for permitting automatic engine
stopping and maximum vehicle speed for permitting automatic engine
stopping may be adjusted to lower or raise the maximum accessory
load and maximum vehicle speed at which the engine may be
automatically stopped. Method 400 proceeds to 412.
[0064] At 410, method 400 adjusts entry conditions for automatic
engine stopping and starting to base levels. Method 400 requires
that electric energy storage device SOC be greater than the minimum
electric energy storage device SOC threshold for automatic engine
stopping for an electric energy storage device exhibiting lower
degradation (curve 312) when the actual percentage of electric
energy storage device useful life consumed is less than the
expected electric energy storage device useful life threshold.
Method 400 requires that accessory load be less than a maximum
accessory load threshold for automatic engine stopping for an
electric energy storage device exhibiting lower degradation (curve
314) when the actual percentage of electric energy storage device
useful life consumed is less than the expected electric energy
storage device useful life threshold. Additionally, method 400
requires that electric energy storage device SOC be greater than
the minimum electric energy storage device SOC threshold for
automatic engine stopping for an electric energy storage device
exhibiting lower degradation when actual percentage of DC/DC
converter useful life consumed is less than the expected DC/DC
converter useful life threshold. Method 400 also requires that
accessory load be less than a maximum accessory load threshold for
automatic engine stopping for an electric energy storage device
exhibiting lower degradation when actual percentage of DC/DC
converter useful life consumed is less than the expected DC/DC
converter useful life threshold. Method 400 also requires that
electric energy storage device SOC be greater than the minimum
electric energy storage device SOC threshold for automatic engine
stopping when an electric energy storage device is exhibiting lower
degradation and when actual percentage of power relay useful life
consumed is greater than the expected power relay useful life
threshold. Method 400 requires that accessory load be less than a
maximum accessory load threshold (curve 314) for automatic engine
stopping for an electric energy storage device exhibiting lower
degradation when actual percentage of DC/DC converter useful life
consumed is less than the expected DC/DC converter useful life
threshold.
[0065] Regarding engine starting requirements, method 400 requires
that electric energy storage device SOC be greater than the minimum
electric energy storage device SOC threshold for automatic engine
starting for an electric energy storage device exhibiting lower
degradation when the actual percentage of electric energy storage
device useful life consumed is less than the expected electric
energy storage device useful life threshold. Method 400 also
requires that accessory load be less than a maximum accessory load
threshold for automatic engine starting for an electric energy
storage device exhibiting lower degradation when the actual
percentage of electric energy storage device useful life consumed
is less than the expected electric energy storage device useful
life threshold. Method 400 also requires that electric energy
storage device SOC be greater than the minimum electric energy
storage device SOC threshold for automatic engine starting for an
electric energy storage device exhibiting lower degradation when
actual percentage of DC/DC converter useful life consumed is less
than the expected DC/DC converter useful life threshold. Method 400
also requires that accessory load be less than a maximum accessory
load threshold for automatic engine starting for an electric energy
storage device exhibiting lower degradation when actual percentage
of DC/DC converter useful life consumed is less than the expected
DC/DC converter useful life threshold. Method 400 also requires
that electric energy storage device SOC be greater than the minimum
electric energy storage device SOC threshold for automatic engine
starting for an electric energy storage device that is exhibiting
lower degradation and when actual percentage of power relay useful
life consumed is greater than the expected power relay useful life
threshold. Method 400 also requires that accessory load be less
than a maximum accessory load threshold for automatic engine
starting for an electric energy storage device that is exhibiting
lower degradation and when actual percentage of power relay useful
life consumed is greater than the expected power relay useful life
threshold. Method 400 proceeds to 412.
[0066] At 412, method 400 automatically stops and starts the engine
according to the entry condition thresholds and entry conditions
previously mentioned. The engine may automatically be stopped and
started via a controller judging whether or not the entry
conditions previously mentioned have been met. Method 400 proceeds
to exit.
[0067] Thus, the method of FIG. 4 provides for a vehicle operating
method, comprising: estimating an amount of electric energy storage
device useful life consumed via a controller; adjusting automatic
engine stop/start thresholds in response to the amount of electric
energy storage device useful life consumed; and starting or
stopping the engine in response to the automatic engine start/stop
thresholds via the controller. The method includes where the
automatic engine stop/start thresholds include a minimum electric
energy storage device state of charge threshold for permitting
automatic engine stopping responsive to a percentage of useful
electric energy storage device life consumed. The method includes
where the automatic engine stop/start thresholds include a maximum
accessory load threshold for permitting automatic engine stopping
responsive to a percentage of useful electric energy storage device
life consumed.
[0068] In some examples, the method includes where the automatic
engine stop/start thresholds include a maximum vehicle speed for
permitting automatic engine stopping responsive to a percentage of
useful electric energy storage device life consumed. The method
includes where the automatic engine stop/start thresholds include a
minimum electric energy storage device state of charge threshold
for permitting automatic engine starting responsive to a percentage
of useful electric energy storage device life consumed. The method
includes where the automatic engine stop/start thresholds include a
maximum accessory load threshold for permitting automatic engine
starting responsive to a percentage of useful electric energy
storage device life consumed. The method includes where the
automatic engine stop/start thresholds include a maximum vehicle
speed for permitting automatic engine stopping responsive to a
percentage of useful electric energy storage device life
consumed.
[0069] The method of FIG. 4 also provides for a vehicle operating
method, comprising: estimating an amount of useful life consumed of
a device via a controller, the amount of useful life consumed a
summation of individual estimates; adjusting automatic engine
stop/start thresholds in response to the amount of useful life
consumed; and automatically starting or stopping the engine in
response to the automatic engine start/stop thresholds via the
controller. The method includes where the summation of individual
estimates includes estimates of DC/DC converter life consumed. The
method includes where the summation of individual estimates
includes estimates of electric energy storage device life consumed.
Note that maximum thresholds or limits described herein may be
referred to as upper thresholds or limits. Likewise, minimum
thresholds or limits described herein may be referred to as lower
thresholds or limits.
[0070] In some examples, the method includes where the summation of
individual estimates includes estimates of power relay life
consumed. The method includes where the automatic engine stop/start
thresholds include a minimum electric energy storage device state
of charge threshold for permitting automatic engine stopping
responsive to a percentage of useful electric energy storage device
life consumed. The method includes where the automatic engine
stop/start thresholds include a maximum accessory load threshold
for permitting automatic engine stopping responsive to a percentage
of useful electric energy storage device life consumed. The method
includes where the automatic engine stop/start thresholds include a
maximum vehicle speed for permitting automatic engine stopping
responsive to a percentage of useful electric energy storage device
life consumed.
[0071] Note that the example control and estimation routines
included herein can be used with various engine and/or vehicle
system configurations. The control methods and routines disclosed
herein may be stored as executable instructions in non-transitory
memory and may be carried out by the control system including the
controller in combination with the various sensors, actuators, and
other engine hardware. The specific routines described herein may
represent one or more of any number of processing strategies such
as event-driven, interrupt-driven, multi-tasking, multi-threading,
and the like. As such, various actions, operations, and/or
functions illustrated may be performed in the sequence illustrated,
in parallel, or in some cases omitted. Likewise, the order of
processing is not necessarily required to achieve the features and
advantages of the example embodiments described herein, but is
provided for ease of illustration and description. One or more of
the illustrated actions, operations and/or functions may be
repeatedly performed depending on the particular strategy being
used. Further, at least a portion of the described actions,
operations and/or functions may graphically represent code to be
programmed into non-transitory memory of the computer readable
storage medium in the control system. The control actions may also
transform the operating state of one or more sensors or actuators
in the physical world when the described actions are carried out by
executing the instructions in a system including the various engine
hardware components in combination with one or more
controllers.
[0072] This concludes the description. The reading of it by those
skilled in the art would bring to mind many alterations and
modifications without departing from the spirit and the scope of
the description. For example, I3, I4, I5, V6, V8, V10, and V12
engines operating in natural gas, gasoline, diesel, or alternative
fuel configurations could use the present description to
advantage.
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