U.S. patent application number 14/230280 was filed with the patent office on 2014-10-16 for method of controlling an engine of a motor vehicle.
This patent application is currently assigned to Ford Global Technologies, LLC. The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Ian HALLERON, David HESKETH, Christopher Edward PEDLAR, Themi Philemon PETRIDIS.
Application Number | 20140309910 14/230280 |
Document ID | / |
Family ID | 48483680 |
Filed Date | 2014-10-16 |
United States Patent
Application |
20140309910 |
Kind Code |
A1 |
HESKETH; David ; et
al. |
October 16, 2014 |
METHOD OF CONTROLLING AN ENGINE OF A MOTOR VEHICLE
Abstract
A method of controlling an engine of a stop-start enabled motor
vehicle is disclosed in which the conditions used to determine
whether to stop or start the engine are changed based upon whether
maximum driver comfort or maximum fuel economy are requested by a
driver of the motor vehicle.
Inventors: |
HESKETH; David; (Stock,
GB) ; PETRIDIS; Themi Philemon; (Bishop's Stortford
Herts, GB) ; HALLERON; Ian; (Danbury, GB) ;
PEDLAR; Christopher Edward; (Chelmsford Essex, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Assignee: |
Ford Global Technologies,
LLC
Dearborn
MI
|
Family ID: |
48483680 |
Appl. No.: |
14/230280 |
Filed: |
March 31, 2014 |
Current U.S.
Class: |
701/112 |
Current CPC
Class: |
Y02T 10/40 20130101;
F02N 2200/105 20130101; Y02T 10/48 20130101; B60W 20/10 20130101;
F02N 11/0814 20130101; G05B 13/02 20130101; F02N 11/0818 20130101;
F02N 11/0822 20130101 |
Class at
Publication: |
701/112 |
International
Class: |
F02N 11/08 20060101
F02N011/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2013 |
GB |
1306504.0 |
Claims
1. A method of controlling an engine of a stop-start enabled motor
vehicle, the engine having at least first and second stop-start
modes of operation in each of which stopping of the engine is
effected when respective stop conditions are met and starting of
the engine is effected when respective start conditions are met and
a user input device to select the stop-start mode of operation to
be used, wherein the method comprises: providing a first set of
engine stop conditions for use when the first stop-start mode of
operation is selected that is more restrictive than a second set of
engine stop conditions for use when the second stop-start mode of
operation is selected; and providing a first set of engine start
conditions for use when the first stop-start mode of operation is
selected that are less restrictive that a second set of engine
start conditions for use when the second stop-start mode of
operation is selected.
2. The method of claim 1, wherein there is at least one further
engine stop-start mode of operation and a corresponding set of stop
conditions and the further stop conditions are less restrictive
than the first set of stop conditions and more restrictive than the
second set of stop conditions.
3. The method of claim 1, wherein there is at least one further
engine stop-start mode of operation and a corresponding set of
start conditions and the start conditions are more restrictive than
the first set of start conditions and less restrictive than the
second set of start conditions.
4. The method of claim 1, wherein the first set of stop and start
conditions increase the opportunities to start the engine and
minimise the opportunities to stop the engine so as to bias control
of the engine towards driver comfort.
5. The method of claim 1, wherein the second set of stop and start
conditions maximize the opportunities to stop the engine and
minimise the opportunities to start the engine so as to bias
control of the engine towards fuel economy.
6. A system for controlling the operation of an engine of a
stop-start enabled motor vehicle, the engine having at least first
and second engine stop-start modes of operation in each which
stopping of the engine is effected when respective stop conditions
are met and starting of the engine is effected when respective
start conditions are met, the system comprising: a stop-start
controller arranged to receive information regarding the operating
state of the motor vehicle, information regarding operation of one
or more vehicle controls by an operator of the motor vehicle and
information from a human machine interface of which engine
stop-start mode of operation is selected for use, wherein the
stop-start controller is operable to use a first set of engine stop
conditions when the first engine stop-start mode of operation is
selected and use a second set of engine stop conditions when the
second engine stop-start mode of operation is selected, the first
set of stop conditions being more restrictive than the second set
of stop conditions and is operable to use a first set of engine
start conditions when the first engine stop-start mode of operation
is selected and use a second set of engine start conditions when
the second engine stop-start mode of operation is selected, the
first set of start conditions being less restrictive than the
second set of start conditions.
7. The system of claim 6, wherein there is at least one further
engine stop-start mode of operation and a corresponding set of stop
conditions and the further stop conditions are less restrictive
than the first set of stop conditions and more restrictive than the
second set of stop conditions.
8. The system of claim 6, wherein there is at least one further
engine stop-start mode of operation and a corresponding set of
start conditions and the further start conditions are more
restrictive than the first set of start conditions and less
restrictive than the second set of start conditions.
9. The system of claim 6, wherein the first set of stop and start
conditions increase the opportunities to start the engine and
minimise the opportunities to stop the engine so as to bias control
of the engine towards driver comfort.
10. The system of claim 6, wherein the second set of stop and start
conditions maximize the opportunities to stop the engine and
minimise the opportunities to start the engine so as to bias
control of the engine towards fuel economy.
11. A method of controlling a vehicle comprising: in response to
user selection, selectively auto-starting an engine in response to
a first or second set of engine start conditions and selectively
auto-stopping the engine in response to a corresponding first or
second set of stop conditions, wherein for a same drive cycle the
first sets of stop and start conditions result in non-zero fewer
engine stops than the second sets of stop and start conditions.
12. The method of claim 11, wherein the first set of engine stop
conditions is more restrictive than the second set of engine stop
conditions and the second set of engine start conditions is more
restrictive than the first set of engine start conditions.
13. The method of claim 12, further comprising, in response to the
user selection, selectively starting the engine in response to a
third set of engine start conditions and stopping the engine in
response to a third set of engine stop conditions, the third set of
start conditions being more restrictive than the first set of start
conditions and less restrictive than the second set of start
conditions and the third set of stop conditions being less
restrictive than the first set of stop conditions and more
restrictive than the second set of stop conditions.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims foreign priority benefits under 35
U.S.C. .sctn.119(a)-(d) to GB 1306504.0 filed Apr. 10, 2013, which
is hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] This invention relates to motor vehicles and in particular
to a method and apparatus for controlling the operation of an
engine of a stop-start enabled motor vehicle.
BACKGROUND
[0003] It is well known to provide a motor vehicle with apparatus
often referred to as a stop-start system to automatically stop and
start the engine when a number of predefined conditions are found
to be present.
[0004] Such stop-start systems reduce fuel consumption and
emissions by stopping the engine when it would otherwise by
unnecessarily idling.
[0005] Typically, a number of other components or systems such as,
for example and without limitation, a climate control system, an
instrument cluster, a brake system and an electric power supply
system have a modified operation to provide an appropriate behavior
during the various engine operating states.
[0006] For example, the loss of engine idling when the engine has
been automatically stopped means that power is unavailable for
typical engine driven ancillaries e.g. the alternator, vacuum pump,
water pump and air conditioning compressor. This lack of power
often leads to reduced performance of the associated systems and
this loss in performance may be noticeable by an occupant of the
motor vehicle.
[0007] The most noticeable loss is that associated with the climate
control system. To maintain cabin comfort in winter, a source of
heat energy must be transferred from the engine to the cabin heater
matrix and to maintain cabin comfort in summer, a source of cold
refrigerant must be supplied to the evaporator or heat exchanger in
the cabin.
[0008] As neither is normally possible with the engine stopped, the
climate control system often automatically operates in an attempt
to maximize the time that acceptable cabin comfort can be
maintained by taking mitigating actions such as changing the
position of air control flaps and reducing the blower speed.
Ultimately, the climate system may request that the engine be
automatically restarted to maintain cabin comfort for a longer
period, or request that further engine stops be prevented until a
range of parameters within the climate system is met. Such
parameters may include, in winter, ensuring the engine coolant is
sufficiently warm to provide heat to the cabin and, in summer,
ensuring that the evaporator is sufficiently cold to prevent the
formation of damp or musty smells in the cabin.
[0009] In order to maximize stop availability whilst minimizing the
impact on cabin climate comfort, an inevitable trade-off must
therefore be made by the system designers and this trade-off is
likely to be sub-optimal for many vehicle occupants, leading to
dissatisfaction with vehicle performance.
[0010] It is further known to provide a stop-start enabled motor
vehicle with a driver selectable switch, which can be used to
de-activate the stop-start system.
[0011] However, although such a switch enables a driver to manually
deactivate the automatic stop start behavior of the motor vehicle
this will result in an unacceptable increase in both fuel
consumption and engine emissions.
SUMMARY
[0012] It is an object of the invention to provide a method of
controlling an engine of a stop-start enabled motor vehicle that
enables a user of the motor vehicle to adjust the stop-start
behavior of the motor vehicle to better suit the current operating
conditions of the motor vehicle.
[0013] According to a first aspect of the invention there is
provided a method of controlling an engine of a stop-start enabled
motor vehicle, the engine having at least first and second
stop-start modes of operation in each of which stopping of the
engine is effected when respective stop conditions are met and
starting of the engine is effected when respective start conditions
are met and a user input device to select the stop-start mode of
operation to be used wherein the method comprises providing a first
set of engine stop conditions for use when the first stop-start
mode of operation is selected that is more restrictive than a
second set of engine stop conditions for use when the second
stop-start mode of operation is selected and further comprises a
first set of engine start conditions for use when the first
stop-start mode of operation is selected that are less restrictive
that a second set of engine start conditions for use when the
second stop-start mode of operation is selected.
[0014] This has the advantage that the opportunities to stop the
engine are increased when the second set of stop conditions are
used compared to the first set of stop conditions and the
opportunities to start the engine are increased when the first set
of start conditions are used compared to the second set of start
conditions.
[0015] There may be at least one further engine stop-start mode of
operation and a corresponding set of stop conditions and the
further stop conditions may be less restrictive than the first set
of stop conditions and may be more restrictive than the second set
of stop conditions.
[0016] There may be at least one further engine stop-start mode of
operation and a corresponding set of start conditions and the start
conditions may be more restrictive than the first set of start
conditions and less restrictive than the second set of start
conditions.
[0017] The first set of stop and start conditions may increase the
opportunities to start the engine and may reduce the opportunities
to stop the engine so as to bias control of the engine towards
driver comfort.
[0018] The second set of stop and start conditions may maximize the
opportunities to stop the engine and may minimize the opportunities
to start the engine so as to bias control of the engine towards
fuel economy.
[0019] According to a second aspect of the invention there is
provided a system for controlling the operation of an engine of a
stop-start enabled motor vehicle, the engine having at least first
and second engine stop-start modes of operation in each which
stopping of the engine is effected when respective stop conditions
are met and starting of the engine is effected when respective
start conditions are met, the system comprising a stop-start
controller arranged to receive information regarding the operating
state of the motor vehicle, information regarding operation of one
or more vehicle controls by an operator of the motor vehicle and
information from a human machine interface of which engine
stop-start mode of operation is selected for use, wherein the
stop-start controller is operable to use a first set of engine stop
conditions when the first engine stop-start mode of operation is
selected and use a second set of engine stop conditions when the
second engine stop-start mode of operation is selected, the first
set of stop conditions being more restrictive than the second set
of stop conditions and is operable to use a first set of engine
start conditions when the first engine stop-start mode of operation
is selected and use a second set of engine start conditions when
the second engine stop-start mode of operation is selected, the
first set of start conditions being less restrictive than the
second set of start conditions.
[0020] This has the advantage that the opportunities to stop the
engine are increased when the second set of stop conditions are
used compared to the first set of stop conditions thereby
increasing fuel economy and the opportunities to start the engine
are increased when the first set of start conditions are used
compared to the second set of start conditions thereby increasing
driver comfort.
[0021] There may be at least one further engine stop-start mode of
operation and a corresponding set of stop conditions and the
further stop conditions may be less restrictive than the first set
of stop conditions and may be more restrictive than the second set
of stop conditions.
[0022] There may be at least one further engine stop-start mode of
operation and a corresponding set of start conditions and the
further start conditions may be more restrictive than the first set
of start conditions and may be less restrictive than the second set
of start conditions.
[0023] The first set of stop and start conditions may increase the
opportunities to start the engine and may reduce the opportunities
to stop the engine so as to bias control of the engine towards
driver comfort.
[0024] The second set of stop and start conditions may maximize the
opportunities to stop the engine and may minimize the opportunities
to start the engine so as to bias control of the engine towards
fuel economy.
[0025] The invention will now be described by way of example with
reference to the accompanying drawing of which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic plan view of a motor vehicle according
to a third aspect of the invention having a stop-start system
according to a second aspect of the invention;
[0027] FIGS. 2a and 2b are a table indicating various engine stop
conditions used in a method and stop-start system according to
first and second aspects of the invention; and
[0028] FIG. 3 is a high level flow chart showing one embodiment of
a method according to the first aspect of the invention.
DETAILED DESCRIPTION
[0029] As required, detailed embodiments of the present invention
are disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention that
may be embodied in various and alternative forms. The figures are
not necessarily to scale; some features may be exaggerated or
minimized to show details of particular components. Therefore,
specific structural and functional details disclosed herein are not
to be interpreted as limiting, but merely as a representative basis
for teaching one skilled in the art to variously employ the present
invention.
[0030] With particular reference to FIG. 1 there is shown a motor
vehicle 1 having in this case four road wheels 5.
[0031] An engine 10 is arranged to drive at least two of the road
wheels 5 via a driveline (not shown).
[0032] Operation of the engine 10 is controlled by a stop-start
system comprising a stop-start controller 20, a human machine
interface 21, a number of vehicle operational inputs 22 and a
number of driver inputs 24.
[0033] The human machine interface (HMI) 21 can be in the form of a
switch having a number of operational positions or be a touch
screen device in which a user can input demands/selections and in
some cases via which messages can be output to the user.
[0034] The vehicle operational inputs 22 may include one or more
of, for example and without limitation, the current speed of the
motor vehicle 1, the temperature of engine coolant, the rotational
speed of the engine, ambient temperature, cabin temperature,
climate control evaporator temperature and vehicle occupancy.
[0035] The driver inputs 24 will depend upon whether the motor
vehicle 1 has an automatic or manual transmission but may include
two or more of, for example and without limitation, accelerator
pedal position, clutch pedal position, brake pedal position, brake
pedal load, transmission engagement state (engaged/neutral) and
parking brake (handbrake) state.
[0036] As is well known in the art, the vehicle operational inputs
22 and the driver inputs 24 are used in combination by the
stop-start controller 20 to determine when it is possible/safe to
stop and start the engine 10 and there are many possible strategies
currently in use. These include but are not limited to stop in
gear, stop in neutral and free rolling (engine stopped while the
vehicle is moving).
[0037] In the case of the stop-start system shown in FIG. 1 the HMI
21 is used to vary the operation of the stop-start system and
includes at least three instructional outputs or selections.
[0038] If the HMI 21 is in the form of a switch these outputs will
correspond to a first switch position in which the stop-start
conditions used to decide whether to stop and start the engine 10
are optimized to provide the best possible comfort for a user of
the motor vehicle 1, a second switch position in which the
stop-start conditions used to decide whether to stop and start the
engine 10 are optimized to provide the best possible economy and a
third switch position in which stop-start operation of the engine
is disabled.
[0039] A similar arrangement may be provided if the HMI 21 is a
touch screen device with the user being provided with three options
corresponding to the first, second and third switch positions
referred to above. However, in the case of an HMI 21 in the form of
a touch screen device many more options can be provide so that a
user such as a driver of the motor vehicle 1 can customize the
operation of the stop-start system to meet their particular
preferences. For example, economy can be optimized while retaining
a user selectable level of climate control or of steering
assistance so that the stop-start conditions lie somewhere between
those optimized for comfort and economy.
[0040] Although more than three switch positions can be provided in
the case of the use of a switch, it will be appreciated that the
range of options available to a user can be far greater if a touch
screen HMI device 21 is used.
[0041] In operation the stop-start controller 20 of the stop-start
system analyses the vehicle and driver information 22 and 24 it
receives and compares these to sets of conditions that need to be
met to stop or start the engine 10 for the current driver
demand/selection as input via the HMI 21.
[0042] For example, if the driver selects the engine be run
continuously then no stop-start conditions have to be set because,
irrespective of the various vehicle and driver inputs 22 and 24
received by the stop-start controller 20, the engine 10 is
continuously run while motor vehicle 1 is in a `Key-On` state.
[0043] Similarly, if the driver selects comfort to be maximized,
the stop-start conditions are set to ensure that cabin temperature,
for example, is not compromised by stopping of the engine 10 even
if this results in a reduction in the fuel economy of the motor
vehicle 1. This normally results in the opportunities for stopping
the engine 10 being reduced compared to a conventional stop-start
system.
[0044] If the driver selects economy to be maximized, the
stop-start conditions are set to ensure that whenever possible the
engine 10 is stopped even if this results in a reduction in comfort
for the driver. This setting may, for example, be used by a driver
if the ambient temperature is not too hot or too cold because in
such a situation neither heating nor cooling of the cabin may be
essential. Also, if the ambient humidity is low a driver may select
the economy setting because it is easier to tolerate even a
relatively high cabin temperature if there is low humidity. The use
of the economy setting will normally result in the opportunities
for stopping the engine 10 being increased compared to a
conventional stop-start system.
[0045] Therefore a first set of engine stop conditions are provided
for use when the first or comfort stop-start mode of operation is
selected and a second set of engine stop conditions are provided
for use when the second stop-start mode of operation is selected.
It will be appreciated that the first set of conditions will reduce
the opportunities to stop the engine compared to the second set of
conditions.
[0046] Examples of various control options for these comfort and
economy stop settings are shown in the table included as FIGS. 2a
and 2b and will be described in more detail hereinafter.
[0047] Although the invention has been described with respect to a
stop-start enabled motor vehicle in the form of a `micro-hybrid`
having only an internal combustion engine as a source of motive
power it will be appreciated by those skilled in the art that it
could also be applied with advantage to a stop-start enabled motor
vehicle in the form of a `mild or full-hybrid` motor vehicle having
an internal combustion engine and one or more electric motors as
sources of motive power.
[0048] In the case of a `mild or full-hybrid` motor vehicle the
automatic stopping and starting is not only controlled by the
actions of the driver but also without driver intervention to
maximize full economy and reduce fuel consumption by using the
electric motor or motors to drive the motor vehicle when the
operational conditions permit. In such a case, the HMI 21 can be
used by a user or driver of the motor vehicle 1 to customize the
circumstances in which electric power is utilized by reducing the
opportunities for use of electric power when the comfort setting is
selected and increasing the opportunities for use of electric power
when economy mode is chosen. It will however be appreciated that
such changes will be restricted by the physical capability of the
electrical drive to provide power, the electrical storage capacity
of the electric system of the motor vehicle and the requirement to
use electric power to reduce fuel consumption and emissions.
[0049] Referring now to FIG. 3 there is shown a high level flow
chart of a method of controlling an engine of a stop-start enabled
motor vehicle such as the engine 10 shown in FIG. 1.
[0050] The method shown starts at box 110 where the engine 10 is
running but it will be appreciated that prior to this step there
will be the steps of `Key-On` and a manual starting of the engine
10.
[0051] From box 110 the method advances to box 115 where it is
checked whether the driver has selected using the HMI 21 to
deactivate stop-start running so that the engine 10 is run
continuously while a `Key-On` state persists. It will be
appreciated that in some cases such as when the engine 10 is cold
stop-start operation is not possible and so box 115 could also
check to see whether stop-start operation is possible.
[0052] If continuous running is to be used, the method returns to
box 110 and the engine remains running However, if continuous
running is not to be used then the method advances to box 120 where
it is checked whether the economy mode has been selected and, if it
has, the method advances to box 130 and, if it has not, the method
advances to box 125. It will be appreciated that alternative logic
could be used to obtain the same effect.
[0053] For example and without limitation, the method could advance
from box 110 to box 125 and then check whether the comfort mode is
active and, if it is not, proceed to box 120 but otherwise continue
to box 135. Alternatively, a single test could be used to replace
boxes 115, 120 and 125 such as "Is driver requested selection,
`continuous`, `economy` or `comfort`" "If `continuous` go to 110,
if `economy` go to 130 and if `comfort` go to 135".
[0054] Assuming the economy mode is active, then the method
advances from box 120 to box 130 it is checked whether economy
optimized stop conditions are present. That is to say, if the
economy mode has been selected, a predefined number of economy
biased stop conditions are set for use in determining whether to
stop the engine 10.
[0055] If, when checked in box 130, the economy stop conditions are
not present, the method returns to box 110 with the engine 10 still
running However, if when checked in box 130 the economy stop
conditions are present, the method advances to box 140 and the
necessary actions to stop the engine 10 are taken. The method then
advances to box 150 where the engine 10 is stationary in a stopped
state.
[0056] It is then checked in box 160 whether start conditions are
present and preferably whether economy optimized start conditions
are present. That is to say, if the economy mode has been selected,
a predefined number of economy biased start conditions are set for
use in determining whether to start the engine 10.
[0057] If, when checked in box 160, the economy start conditions
are not present, the method returns to box 150 with the engine 10
still stopped. However, if when checked in box 160 the economy
start conditions are present, the method advances to box 170 and
the necessary actions to start the engine 10 are taken. The method
then returns to box 110 with the engine 10 running
[0058] Returning now to box 125, where it has been determined that
the comfort mode has been selected, the method advances from box
125 box 135. A further option (not shown) could be provided to
allow for system errors by making the box 125 a test for whether
the comfort mode has been selected and, if it has not been
selected, returning to box 110 and, if it has been selected,
continuing to box 135 as shown on FIG. 3.
[0059] Assuming the comfort mode is active then in box 135 it is
checked whether comfort optimized stop conditions are present. That
is to say, if the comfort mode has been selected, a predefined
number of comfort biased stop conditions are set for use in
determining whether to stop the engine 10.
[0060] If, when checked in box 135, the comfort stop conditions are
not present the method returns to box 110 with the engine 10 still
running However, if when checked in box 135 the comfort stop
conditions are present, the method advances to box 145 and the
necessary actions to stop the engine 10 are taken. The method then
advances to box 155 where the engine 10 is stationary in a stopped
state.
[0061] It is then checked in box 165 whether start conditions and
preferably comfort optimized start conditions are present. That is
to say, if the comfort mode has been selected, a predefined number
of comfort biased start conditions are set for use in determining
whether to start the engine 10.
[0062] If, when checked in box 165, the comfort start conditions
are not present the method returns to box 155 with the engine 10
still stopped. However, if when checked in box 165 the comfort
start conditions are present, the method advances to box 175 and
the necessary actions to start the engine 10 are taken. The method
then returns to box 110 with the engine 10 running
[0063] It will be appreciated that various features of the method
have been omitted from FIG. 3. For example, if at any time a
vehicle `Key-Off` event occurs then the method will end. In
addition, if the driver changes the required operation selection at
any time then operation of the engines will immediately be changed
to reflect the change in driver selection.
[0064] FIGS. 2a and 2b show a table providing examples of some
possible stop conditions (as checked in boxes 130 and 135 on FIG.
3) for the economy and comfort modes. FIGS. 2a and 2b also show
corresponding start conditions (as checked in boxes 160 and 165 on
FIG. 3).
[0065] Referring now to FIGS. 2a and 2b the differences in the stop
conditions between the comfort setting and the economy setting are
shown in more detail.
[0066] In column `A` the affected subsystem or action is given and
in columns `B` and `C` different stop and start conditions are
shown.
[0067] The conditions shown in column `B` are various examples of a
first set of stop and start conditions used when a comfort
selection has been made by the driver. That is to say, control of
the engine 10 is biased towards driver comfort and not economy when
this driver selection is made. These conditions restrict stopping
of the engine 10 and encourage starting of the engine 10.
[0068] The conditions shown in column `C` are various examples of a
second set of stop and start conditions used when an economy
selection has been made by the driver. That is to say, control of
the engine 10 is biased towards economy and not driver comfort when
this driver selection is made. These conditions encourage stopping
of the engine 10 and restrict starting of the engine 10.
[0069] Therefore the first set of stop conditions are more
restrictive than the second set of stop conditions and the second
set of start conditions are more restrictive than the first set of
start conditions.
[0070] In the first example shown in FIG. 2a, the affected system
is the climate control system and in column `B`, which are the
comfort conditions, the engine 10 is only stopped if tightly
defined climate comfort criteria such as, for example, cabin
temperature, evaporator temperature or humidity are met. The engine
10 is started if tightly defined climate comfort criteria such as
those referred to above are not met. In column `C` corresponding
economy mode conditions are to stop the engine 10 irrespective of
cabin comfort conditions and to start the engine 10 based only on
driver intention to drive away and ignore any cabin comfort
conditions.
[0071] In the second example given in FIG. 2a, the affected system
is driver controls and in column `B`, which are the comfort
conditions, the engine 10 is only stopped when the transmission is
in neutral and the clutch pedal is fully released. That is to say,
the engine stop is a Stop in Neutral (SIN) stop. The engine 10 is
started when the clutch is pressed. That is to say, the engine
start is a Start in neutral (SIN) start. In column `C`
corresponding economy mode conditions are to permit stop in gear
(SIG) engine stops as well as SIN engine stops and to permit SIG
and SIN engine starts.
[0072] In the third example given in Table 2a, the affected system
is a clutch pedal state determination. Clutch pedal position is
normally used in the case of a manual transmission motor vehicle as
a key factor in deciding whether to stop the engine. To achieve
this clutch pedal position is normally sensed using a clutch pedal
sensor or one or more switches associated with the clutch pedal and
the state of engagement of a drive clutch between the engine 10 and
a transmission (not shown) of the motor vehicle 1 is inferred based
upon the sensed clutch pedal position. In such a system three
ranges of clutch pedal movement are often defined, released,
pressed and depressed.
[0073] In the released range it is assumed that the clutch pedal is
not being touched, in the pressed range the clutch pedal has been
moved beyond the released range and in the depressed range the
clutch pedal has been moved beyond the pressed range. Expressed in
percentages a released range may be in the order of 0% to 30%
travel in the depressed direction, the pressed range may be in the
order of 8% to 80% travel in the depressed direction and the
depressed range may be in the order of 65 to 100% of travel in the
depressed direction.
[0074] In column `B` the comfort conditions are "Only stop the
engine if the clutch pedal is fully released". This condition
indicates that the driver intends to stop for an extended period of
time and hence to maximize the comfort of the driver, those stops
which could be result in a short duration stop are prevented by
detecting that the driver is resting their foot on the clutch pedal
and restart the engine 10 when the clutch pedal is slightly
pressed.
[0075] In column `C` the economy conditions are "Allow an engine
stop even if the clutch pedal is still partially pressed", even
though this condition indicates that the driver may not intend to
stop for an extended period of time. Such a condition maximizes the
stop opportunities and fuel can be saved and restart the engine 10
when the clutch pedal is partially pressed.
[0076] In the fourth example shown in FIG. 2a, the affected system
is a brake pedal state determination for use on automatic
transmission applications. Brake pedal position or applied load is
normally used in the case of an automatic transmission motor
vehicle as a key factor in deciding whether to stop the engine. In
the case of brake pedal position this can be sensed using a sensor
associated with the brake pedal and in the case of brake pedal
applied load this can be sensed via a load sensor on the brake
pedal or by sensing the pressure of hydraulic fluid in an
associated braking system.
[0077] In column `B` the stop condition for driver comfort is "Only
stop the engine if the brake pedal is pushed hard". This condition
would in practice be a test such as "Is the applied load greater
than a high threshold value". The application of a high load
implies that the driver intends to stop for an extended period of
time. Since the comfort of the driver is likely to be adversely
affected by frequent short engine stops and starts, stops are only
permitted when the brake pedal is pushed hard. The start condition
for driver comfort is to start the engine 10 when the brake pedal
is moved in a released direction.
[0078] In column `C` the stop economy condition is "Allow stop even
if the brake pedal is only lightly pressed". This condition would
in practice be a test such as "Is the applied load greater than a
lower threshold value but less than a higher threshold value". The
application of a light load implies that the driver may not intend
to stop for an extended period of time but such a stop condition
maximizes the engine stop opportunities. The corresponding start
condition is to start the engine 10 only when the brake pedal is
fully released thereby maximizing engine shutdown time.
[0079] Numerous further stop and start conditions for the comfort
and economy modes are given in FIGS. 2a and 2b but are not
described in detail. It will be appreciated that these could be
used either on their own or in combination with one or more of the
other stop and start conditions. That is to say, a number of these
stop and start conditions could be used in boxes 130, 135 and 160,
165 respectively shown in FIG. 3 depending upon the complexity of
the motor vehicle and the sub-systems present.
[0080] It will also be appreciated that the method steps shown in
FIG. 3 could be used by the stop-start controller 20 to decide when
to stop and start the engine 10.
[0081] Therefore in summary, the invention provides a driver of a
motor vehicle with the opportunity to directly influence a
trade-off between conflicting attributes of `comfort` and `economy`
beyond those offered by the use of a conventional stop/start
deactivate button, without the driver having to consider each
subsystem explicitly.
[0082] For example, one driver may wish to absolutely maximize the
fuel economy of the vehicle, whilst accepting a larger degradation
in cabin comfort. Another driver may accept the operation of the
stop/start system, but only if it results in no discernible
degradation in climate comfort.
[0083] To achieve this functionality the stop-start system of the
motor vehicle includes a driver control which allows the driver to
indicate a general attribute preference. This may be in the form of
a multi-position switch in the instrument panel, or menu options
within a human machine interface such as a cluster display. The
driver can in some embodiments choose from a range of possible
attribute balances such as, for example, "maximum economy",
"balanced" (possibly as per current stop-start operation) and
"maximum comfort").
[0084] The terms `comfort` and `user comfort` as meant herein
include not only the climatic conditions within a passenger
compartment of the motor vehicle but also indicating minimal
intrusiveness of the system and ease of use. For example,
increasing the assistance provided to a steering system would be an
increase in `user comfort` because less physical effort has to be
provided by the driver and reducing the frequency of short stops is
also to be considered a comfort because such short stops can be
annoying to some drivers. The term `Economy mode` or `ECO mode`
means a mode of operation where economy of the motor vehicle is
given preference over comfort and so more opportunities for
stopping the engine are provided and the conditions for restarting
the engine are stricter so that the shutdown period lasts as long
as possible without compromising vehicle operation. Therefore the
comfort mode of operation could be considered to be a reduced
stop/maximum comfort mode of operation and the ECO or economy mode
of operation could be considered to be a maximum stop/maximum fuel
economy mode of operation.
[0085] While exemplary embodiments are described above, it is not
intended that these embodiments describe all possible forms of the
invention. Rather, the words used in the specification are words of
description rather than limitation, and it is understood that
various changes may be made without departing from the spirit and
scope of the invention. Additionally, the features of various
implementing embodiments may be combined to form further
embodiments of the invention.
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