U.S. patent application number 09/849543 was filed with the patent office on 2001-11-22 for vehicle passing speed timer.
This patent application is currently assigned to Detroit Diesel Corporation. Invention is credited to Avery, Richard M. JR., Flammersfeld, Stephen Karl, McKenzie, Ian D..
Application Number | 20010044690 09/849543 |
Document ID | / |
Family ID | 23708821 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010044690 |
Kind Code |
A1 |
Flammersfeld, Stephen Karl ;
et al. |
November 22, 2001 |
Vehicle passing speed timer
Abstract
A system and method for controlling an engine in a vehicle which
allows the vehicle operator to manually request a vehicle speed in
excess of the established vehicle speed limit that includes
establishing a normal vehicle speed limit, establishing a passing
duration period, establishing a passing override reset interval,
and controlling the engine in response to operator input to provide
a greater vehicle speed for a cumulative period not greater than
the passing duration period at any time during the passing override
reset interval. The system and method may include the capability of
establishing a passing speed increment and controlling the vehicle
speed during passing to limit the vehicle to a speed not exceeding
the normal vehicle speed limit plus the passing speed
increment.
Inventors: |
Flammersfeld, Stephen Karl;
(Ann Arbor, MI) ; Avery, Richard M. JR.; (West
Bloomfield, MI) ; McKenzie, Ian D.; (Canton,
MI) |
Correspondence
Address: |
Earl J. LaFontaine
Brooks & Kushman P.C.
22nd Floor
1000 Town Center
Southfield
MI
48075-1351
US
|
Assignee: |
Detroit Diesel Corporation
Detroit
MI
|
Family ID: |
23708821 |
Appl. No.: |
09/849543 |
Filed: |
May 4, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09849543 |
May 4, 2001 |
|
|
|
09430739 |
Oct 29, 1999 |
|
|
|
Current U.S.
Class: |
701/93 ;
180/170 |
Current CPC
Class: |
B60Y 2200/14 20130101;
B60K 31/042 20130101; B60K 31/18 20130101; B60W 30/146
20130101 |
Class at
Publication: |
701/93 ;
180/170 |
International
Class: |
B60K 031/00 |
Claims
What is claimed is:
1. A method for controlling an engine to allow a vehicle operator
to obtain a vehicle passing speed in excess of the normal vehicle
speed limit, the method of comprising: establishing a normal
vehicle speed limit; establishing a passing duration; establishing
a passing override reset interval; controlling the engine in
response to vehicle operator input to provide a vehicle speed
exceeding the normal vehicle speed limit for a cumulative passing
period not greater than the passing duration at any time during the
passing override reset interval.
2. The method of claim 1 further including: establishing a passing
speed increment; and controlling the engine in response to vehicle
operator input to provide a vehicle speed exceeding the normal
vehicle speed limit by an amount not greater than the passing speed
increment for a cumulative passing period not greater than the
passing duration at any time during the passing override reset
interval.
3. The method of claim 1 further including: establishing a warning
period; warning the driver that the vehicle speed will be limited
to the normal vehicle speed limit at the expiration of the warning
period whenever the difference between the passing duration and the
cumulative passing period is less than the warning period and the
vehicle speed exceeds the normal vehicle speed limit.
4. The method of claim 1 further including controlling the engine
to reduce the vehicle speed from a speed exceeding the normal
vehicle speed limit to the normal vehicle speed limit once the
passing duration has lapsed.
5. The method of claim 1 further including: establishing a speed
reduction interval; and including controlling the engine to reduce
the vehicle speed during this speed reduction interval from a speed
exceeding the normal vehicle speed limit to the normal vehicle
speed limit once the passing duration has lapsed.
6. The method of claim 1 further including: setting the cumulative
passing period to zero upon the expiration of the passing override
reset interval.
7. A method for controlling an engine in a vehicle including an
internal combustion engine in communication with an electronic
control module to allow the operator to attain a passing speed
greater than the preset vehicle speed limit, the method comprising:
establishing a normal vehicle speed limit; establishing a passing
speed increment; establishing a passing duration; establishing a
passing override reset interval; controlling the engine in response
to vehicle operator input to provide a vehicle speed exceeding the
normal vehicle speed limit by an amount not greater than the
passing speed increment for a cumulative period not greater than
the passing duration at any time during the passing override reset
interval; and upon the expiration of the passing override reset
interval, resetting the passing duration and the passing override
reset interval to their established values, to allow for operator
requested passing speed exceeding the vehicle speed limit for the
next override reset interval.
8. The method of claim 7 wherein the vehicle speed limit, passing
speed increment, passing duration, and passing override reset
interval values are established during calibration of the engine
control module.
9. The method of claim 7 wherein establishing a passing speed
increment comprises establishing a passing speed increment variable
in the memory associated with the electronic control module with a
preselected value.
10. The method of claim 7 wherein establishing a passing duration
comprises establishing a passing duration variable in the memory
associated with the electronic control module with a preselected
value.
11. The method of claim 7 wherein establishing a passing override
reset interval comprises establishing a passing override reset
interval variable in the memory associated with the electronic
control module with a preselected value.
12. The method of claim 1 wherein the passing override reset
interval is reset at a selected real time, and wherein the operator
is allowed to exceed the normal vehicle speed limit by an amount
not greater than the passing speed increment for a cumulative
period equal to the established value of the passing duration
period whenever the real time is equal to the selected real
time.
13. The method of claim 12 further including: determining whether
the system clock has been changed to a time which would prompt
resetting the passing override reset interval and resetting the
passing duration to its established value, and if such a change has
occurred, maintaining the current value of the duration interval
rather than resetting it to its established value until completion
of the next reset interval to prevent an operator from obtaining
additional speed limit override time by changing the clock.
14. The method of claim 6 further including: resetting the passing
duration to its established value upon the expiration of the
passing override reset interval.
15. The method of claim 14 further including: determining whether
the system clock has been changed to a time which would otherwise
prompt setting the cumulative passing period to zero and resetting
the passing duration to its established time, and if such a change
has occurred, maintaining the cumulative passing period at its
current value and not resetting the passing duration until
completion of the next passing override reset interval.
16. In a method for controlling an engine to allow an operator to
override then normal vehicle speed limit for a cumulative passing
period which is reestablished at a predefined reset interval, a
method of determining whether the operator has tampered with the
engine control system clock to obtain an additional time period for
exceeding the normal vehicle speed limit, the method including:
determining whether the system clock has been changed to a time
which would prompt reinitialization of the passing period during
which the operator may override the vehicle speed limit and, if
such a change has occurred, suspending any steps which would
allocate additional capability to the operator to exceed the normal
speed limit until the completion of the next full reset
interval.
17. In a method for controlling an engine which provides the
operator with a particular operating capability for a time period
which is reestablished at a predefined reset interval, a method of
determining whether the operator has tampered with the engine
control system clock to obtain an additional time period for the
particular capability, the method including: determining whether
the system clock has been changed to a time which would prompt
reinitialization of the time period during which the operator may
utilize the particular capability and, if such a change has
occurred, suspending any steps which would provide the capability
to the operator for any additional time.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 09/430,739, filed Oct. 29, 1999.
TECHNICAL FIELD
[0002] This application relates to a system and method for
controlling an engine to allow a vehicle operator to manually
exceed an established maximum vehicle speed normally imposed by the
vehicle's engine control so that the operator may safely pass other
vehicles.
BACKGROUND ART
[0003] Vehicle engines, and particularly truck engines, are
typically controlled by electronic engine control modules which
implement various methods of controlling the vehicle engine to
optimize the operation of the vehicle. For example, U.S. Pat. No.
5,477,827, assigned to Detroit Diesel Corporation, also the
assignee of the present invention, discloses a system and method
for controlling an engine including the capability of establishing
a normal maximum speed and adding to that maximum speed for a
selected time period as a driver performance incentive whenever the
driver operates the vehicle within certain established performance
goals, such as minimization of idle time, selection of the optimal
transmission gear, maintaining a steady throttle, or reducing the
use of engine driven accessory loads.
[0004] The capability of establishing a normal speed limit provides
fleet managers and individual truck owners with the capability of
insuring that their truck operators drive safely and meet desired
fuel efficiency and other vehicle and engine operation goals.
However, programming electronic engine control modules to establish
vehicle speed limits which may, for example, maximize fuel
efficiency, may otherwise limit the operator's ability to operate
the vehicle in an optimal fashion in an atypical situation, such as
an emergency, or when it is desirable to safely pass other vehicles
at a speed in excess of the established normal speed limit for the
vehicle.
DISCLOSURE OF INVENTION
[0005] It is therefore an object of the present invention to
provide a system and method for controlling an engine which allows
the manufacturer, fleet manager, or vehicle owner to establish a
normal vehicle speed limit, but which also allows the vehicle
operator to exceed that established speed limit to allow the
operator to safely pass other vehicles, or otherwise operate the
vehicle at a higher speed in an emergency.
[0006] It is also an object of the present invention to provide a
system and method for controlling a vehicle engine which provides
the operator the capability of manually operating the vehicle to
exceed the established normal speed limit of the vehicle for a
preselected time period, including warning the operator when the
period during which the operator can manually override the vehicle
speed limit is about to lapse.
[0007] In carrying out the above and other objects, the method of
the present invention includes establishing a normal vehicle speed
limit, establishing a passing duration period, establishing a
passing override reset interval, and controlling the engine in
response to operator input to provide a vehicle speed exceeding the
normal vehicle speed limit for a cumulative passing period not
greater than the passing duration period at any time during the
passing override reset interval. When implemented on an electronic
engine control module, the system and method of the present
invention thus allows an operator to override the normal vehicle
speed limit imposed, for example, by the vehicle fleet manager, for
a limited period of time to allow the vehicle operator to safely
pass other vehicles.
[0008] In one embodiment, the method of the present invention also
includes establishing a passing speed increment. The engine is
controlled to allow the operator to increase the vehicle speed
beyond the normal speed limit by an amount up to but not exceeding
the passing speed increment.
[0009] In another embodiment, the method of the present invention
also includes establishing a warning period, and issuing a warning
to the operator whenever the amount of time that the operator may
manually exceed the normal speed limit is less than the warning
period. In this embodiment, the warning period is preferably set
for an amount of time adequate to allow the vehicle's operator to
complete his passing maneuver and return the vehicle to its normal
speed at or below the established vehicle speed limit.
[0010] In one embodiment, the method of the present invention
includes controlling the engine to gradually reduce the vehicle
speed upon the expiration of the passing duration period to cause
the vehicle to gradually slow to the normal maximum speed
limit.
[0011] These and other objects, features and advantages of the
present invention are readily apparent from the following detailed
description of the best mode for carrying out the invention when
taken in connection with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a block diagram illustrating a system including an
electronic control module which may be programmed to employ the
method of the present invention;
[0013] FIG. 2 is a flow chart generally illustrating the method of
the present invention;
[0014] FIG. 3 is a flow chart illustrating a particular embodiment
of the method of FIG. 2;
[0015] FIG. 4 is a flow chart illustrating another particular
embodiment of the method of FIG. 2; and
[0016] FIG. 5 is a flow chart illustrating yet another particular
embodiment of the method of FIG. 2.
BEST MODE FOR CARRYING OUT THE INVENTION
[0017] Referring now to FIG. 1, a block diagram illustrating a
system including the vehicle passing speed timer according to the
present invention is shown. The system is particularly suited for
use in a vehicle, indicated generally by reference numeral 10,
which includes an engine 12 coupled to a transmission 14 via a
master friction clutch 16. In a preferred embodiment, engine 12 is
a compression-ignition internal combustion engine, such as a four,
six, eight, or more cylinder diesel engine. Transmission 14 is
preferably a multiple gear ratio transmission which is manually or
semi-automatically actuated to select one of the available gear
ratios. Master friction clutch 16 may be manually or automatically
controlled by a clutch actuator (not specifically illustrated) as
is well known in the art.
[0018] Vehicle 10 may also include various sensors 18 for
generating signals indicative of corresponding operational
conditions or parameters of engine 12, transmission 14, clutch 16,
and the like. Sensors 18 are in electrical communication with a
controller 20 via input ports 22. Controller 20 preferably includes
a microprocessor 24 in communication with various computer readable
storage media 26 via data and control bus 28. Computer readable
storage media 26 may include any of a number of known devices which
function as a read-only memory (ROM) 30, random access memory (RAM)
32, keep-alive memory (KAM) 34, and the like. The computer readable
storage media may be implemented by any of a number of known
physical devices capable of storing data representing instructions
executable via a computer such as controller 20. Known devices may
include but are not limited to PROMs, EPROMs, EEPROMs, flash
memory, and the like in addition to magnetic, optical and
combination media capable of temporary or permanent data
storage.
[0019] Computer readable storage media 26 include various program
instructions, software, and control logic to effect control of
various systems and sub-systems of vehicle 10, such as engine 12,
transmission 14, and the like. Controller 20 receives signals from
sensors 18 via input ports 22 and generates output signals which
may be provided to various actuators and/or components via output
ports 36. Signals may also be provided to a display device 40 which
includes various indicators such as lights 38 to communicate
information relative to system operation to the operator of the
vehicle. Preferably, display 40 includes at least one illuminated
indicator such as a check engine light to alert the operator to a
malfunction or error. Display 40 may also include an alphanumeric
portion or other suitable operator interface to provide status
information to a vehicle operator or technician. As such, display
40 represents one or more displays or indicators which may be
located throughout the vehicle interior and exterior but is
preferably located in the cab or interior of the vehicle. A data,
diagnostics, and programming interface 42 may also be selectively
connected to controller 20 via a plug 44 to exchange various
information therebetween. Interface 42 may be used to change values
within the computer readable storage media 26, such as
configuration settings, calibration variables, control logic and
the like. Interface 42 may also be used to retrieve engine
historical information logged as a result of diagnostic or
malfunction codes, including information which is used to assist
personnel performing routine maintenance, or troubleshooting
malfunctions, as well as engine and vehicle operation data,
including data specifically associated with the vehicle's passing
speed timer feature of the present invention, which may be analyzed
to evaluate vehicle operator performance in addition to vehicle
performance.
[0020] Sensors 22 preferably include an engine speed sensor 46.
Engine speed may be detected using any of a number of known sensors
which provide signals indicative of rotational speed for flywheel
18, or various internal engine components such as the crankshaft,
camshaft, or the like. In a preferred embodiment, engine speed is
determined using a timing reference signal generated by a
multi-tooth wheel coupled to the camshaft. A clutch sensor 48 may
be provided to determine the clutch slip or engagement position of
master friction clutch 16. An input shaft speed sensor 50 may be
provided to determine the input speed of transmission 14. An output
shaft sensor 52 may be provided to detect the rotational speed of
output shaft 54. Wheel speed sensors, such as sensor 56, may be
used to provide an indication of the current wheel speed of one or
more vehicle wheels. Such sensors are commonly used in traction
control systems (TCS) and anti-lock braking systems (ABS). Of
course, one or more sensors may provide signals to various other
controllers which are eventually communicated to controller 20
rather than being directly connected via input ports 22 as
illustrated in FIG. 1.
[0021] As will be appreciated by one of ordinary skill in the art,
most vehicle applications will neither require nor utilize all of
the sensors illustrated in FIG. 1. As such, it will be appreciated
that the objects, features, and advantages of the present invention
are independent of the particular manner in which the selected
operating parameters are sensed.
[0022] In operation, controller 20 receives signals from sensors 18
and executes control logic embedded in hardware and/or software to
implement the vehicle passing speed control feature of the present
invention. In a preferred embodiment, controller 20 is the DDEC
controller available from Detroit Diesel Corporation in Detroit,
Mich. Various other features of this controller are described in
detail in U.S. Pat. Nos. 5,477,827 and 5,445,128, the disclosures
of which are hereby incorporated by reference in their
entirety.
[0023] Referring now to FIGS. 2 through 5, flow charts illustrating
representative control logic 100 of a system and method according
to the present invention are shown. As will be appreciated by one
of ordinary skill in the art, the control logic may be implemented
or effected in hardware, software, or a combination of hardware and
software. The various functions are preferably effected by a
programmed microprocessor, such as the DDEC controller, but may
include one or more functions implemented by dedicated electric,
electronic, and integrated circuits. As will also be appreciated,
the control logic may be implemented using any of a number of known
programming and processing techniques or strategies and is not
limited to the order or sequence illustrated here for convenience
only. For example, interrupt or event driven processing is
typically employed in real-time control applications, such as
control of a vehicle engine or transmission. Likewise, parallel
processing or multi-tasking systems and methods may be used to
accomplish the objects, features, and advantages of the present
invention. The present invention is independent of the particular
programming language, operating system, or processor used to
implement the control logic illustrated.
[0024] Block 102 of FIG. 2 represents initialization of various
programming variables and thresholds, one or more of which may be
determined during initialization or reprogramming of the system.
Other values may be retrieved from a non-volatile memory or
computer readable storage media upon engine start-up or other event
such as detection of a fault or error. The reference values are
determined and stored in memory, and preferably include vehicle
speed, normal maximum speed, passing duration, and reset interval.
Vehicle speed may be sensed directly and/or derived from the gear
ratio and/or one or more of sensors 18. The gear ratio may be
communicated by a transmission controller but is preferably a
virtual gear ratio (VGR) which may be determined using the ratio of
transmission input to output speed. One of ordinary skill in the
art will recognize a number of methods to determine transmission
input and output speeds which may be directly sensed or indirectly
inferred from various other sensed parameters.
[0025] The passing duration and reset interval values, as well as
the threshold values for other operating parameters described
hereinafter, are typically programmed into the computer readable
storage media 26 via interface 42 during the initial configuration
of the engine control, or subsequently by the truck owner or fleet
service personnel. The reference values determined by block 102 are
periodically reset or captured (and stored) based on occurrence of
one or more predetermined events.
[0026] The normal maximum road (vehicle) speed limit is typically
set by the vehicle owner or fleet manager at a value which
maximizes fuel efficiency, and/or otherwise maximizes the
economical operation of the vehicle.
[0027] The passing duration is the time period during which the
driver is allowed to manually request vehicle speed in excess of
the normal maximum vehicle speed. In one embodiment, this time
period may be programmed to be between 0 and 255 minutes, and is
typically of about 30 minutes duration. It should be noted,
however, that the system of the present invention can be configured
to accommodate a passing duration period of greater than 255
minutes, if so desired.
[0028] The reset interval is the period of time after which the
electronic control module 20 reestablishes the passing duration, to
enable operation of the vehicle at passing speed in excess of the
programmed vehicle speed limit for a period of time up to the
passing duration period during the next interval. The reset
interval is preferably 24 hours, but it can be any desired time
period. In one embodiment, the reset interval is reestablished
(i.e., a new 24 hour period begins) upon the lapse of the previous
reset interval, regardless of the real time. In an alternative
embodiment, the reset interval may be reestablished at midnight,
based upon the real-time clock in the controller 20 in lieu of, or
in addition to, reestablishing the interval period at the lapse of
the current interval.
[0029] The threshold values for other operating parameters utilized
in the method of the present invention, such as the passing speed
increment the upper activation throttle position, the lower
activation throttle position, the throttle sequence activation
period, the warning period, and/or the ramp-down time are also
preferably initialized at 102 as described above.
[0030] As indicated at 104, if the passing speed timer is enabled,
the system periodically determines whether the operator has made a
manual speed request, such as by moving the foot pedal. It should
be noted that it is contemplated that the passing speed timer of
the present invention will be enabled to provide speed in excess of
the vehicle speed limit to the operator only upon manual input by
the operator, since it is anticipated that this excess speed will
be utilized only for passing or other unanticipated emergencies.
Thus, if the operator has not made a manual request for speed
(e.g., cruise control or another automatic speed control is in
effect), the system exits the passing speed logic 100. If the
driver has made a manual speed request, the system checks, at 106
to determine whether the requested speed is greater than the normal
vehicle speed limit. If the requested speed is within the normal
vehicle speed limit, the system exits logic 100.
[0031] In one embodiment, the passing speed adder of the present
invention is activated by a specific positioning sequence of the
throttle. In this embodiment the driver must press the throttle
pedal above an upper activation throttle position (preferably
between 60 and 99% of full throttle, and most preferably about 95%
of full throttle), then release the throttle to a position below
the lower activation throttle position (preferably between 1 and
50% of full throttle, and most preferably about 5% of full
throttle), then above the upper limit again, then below the lower
limit, and then above the upper limit for a third time, all within
a specified activation period. The activation time may be any
preselected time which is adequate to allow the driver to move the
throttle through the sequence of positions required to activate the
feature. This time period is preferably set to between 1 and 20
seconds, and most preferably about 3 seconds.
[0032] It will be appreciated that other predefined throttle
positioning sequences may be utilized to activate the passing speed
timer of the present invention. The sequence should preferably be
simple, relatively quick to perform, and preferably not a sequence
of throttle positions which might be encountered in the course of
normal driving. Alternatively, a separate switch, or other operator
signaling device, may be utilized to activate the passing speed
adder without departing from the spirit of the present
invention.
[0033] It should be noted that it is contemplated that the method
and system of the present invention will be implemented in
conjunction with other systems and methods which automatically
adjust the vehicle speed limit, such as the fuel economy speed
limit adder disclosed in U.S. Pat. No. 5,477,827, or other
speed-based incentive engine controls. When the method of the
present invention is implemented with, for example, a fuel economy
speed adder, it is contemplated that the passing speed increments,
the fuel economy incentive speed adder, and any other speed adders
will be cumulatively added to the vehicle's normal speed limit when
appropriate. Of course, if desired, a programmable optimal vehicle
speed limit may be provided to limit the cumulative total of the
normal maximum vehicle speed and any cumulative total speed
adders.
[0034] If (as shown at 108) the requested speed is greater than the
normal maximum vehicle speed (and any other speed adders) within a
selected threshold time period (preferably about 20 seconds), the
system will allow the vehicle to operate at a higher speed until
the speed requested by the operator drops or until the passing
duration time expires (as shown at 110). If the speed requested by
the operator is now below the normal limit (at 112), the system
thereafter limits the speed to its normal maximum (at 111). If the
vehicle speed is above the normal maximum, the system checks to
determine whether the passing duration interval has lapsed (at
113). If not, the system continues to monitor the vehicle speed and
the amount of time left in the passing duration interval. If the
passing duration interval has lapsed (at 113) the system restores
the speed limit to the normal maximum (plus any other vehicle speed
adders supported by the system) until such time as the passing
speed timer is again activated (as determined at 104).
[0035] FIG. 3 illustrates one embodiment wherein the logic at 112
of FIG. 1 includes the additional capability of providing speed in
excess of the normal vehicle speed limit up to an amount equal to
an established passing speed increment. The passing speed increment
variable in this embodiment would be established at 102 (in FIG. 1)
as a threshold operating parameter at the time the system is
configured, or at the time the vehicle passing speed feature of the
present invention is enabled. A passing speed increment of between
one and 20 miles per hour is preferably allowed. More preferably,
the passing speed increment is ten miles per hour. Thus, in this
embodiment, the logic at 112 determines whether the requested speed
is greater than the sum of the normal maximum vehicle speed and the
passing speed increment, at 114. If so, the system limits the
vehicle speed to the sum of the maximum vehicle speed and the
passing speed increment for the duration of the request, or for the
remainder of the passing duration, whichever is less. If the
requested speed is not greater than the sum of the vehicle speed
limit and the established passing speed increment, the system
allows the requested speed, at 118 for the duration of the request,
or until the passing duration period has expired, whichever is
sooner.
[0036] FIG. 4 illustrates another embodiment of the present system
and method wherein the logic of block 112 (shown in FIG. 2) also
includes logic for determining whether the passing duration period
has diminished to a period of time less than an established warning
period (at 120). If so, the system issues a warning, at 122, either
in the form of a message on a graphic display, illuminating a
light, activating an alarm, or other method of indicating to the
operator that the passing speed timer is about to lapse and he/she
will shortly be limited to the normal maximum vehicle speed. In one
embodiment the system will cause the check engine lamp (CEL) to
flash rapidly as a warning that the passing speed duration time is
about to lapse. The established warning period is an adequate
amount of time to allow the driver to complete a typical passing
maneuver. In one embodiment this period may be set at 0-255
seconds, and is most preferably about one minute prior to the end
of the passing duration.
[0037] FIG. 5 illustrates additional logic which may be included in
the logic at 112 of FIG. 2 which allows speed in excess of the
normal maximum, but gradually reduces the vehicle speed once the
passing duration period has lapsed, in order to allow the vehicle
to gradually slow to the normal maximum speed limit. The system
determines, at 124, whether the passing duration period is now
equal to zero. If so, the system, at 126 allows the requested speed
in excess of maximum (or, if the embodiment of FIG. 3 is
implemented, the system allows the speed up to the maximum plus any
other speed adders, plus the passing speed increment). The speed
is, however, gradually reduced following expiration of the passing
duration period, preferably at a rate adequate to slow the vehicle
to the normal maximum speed within a preselected speed reduction
time interval. In one embodiment, this ramp-down time is five
seconds. The engine control can, of course, use any of a variety of
methods to slow the vehicle to its normal maximum speed including
controlling the fuel supply, and/or other engine breaking and speed
control techniques such as are disclosed in U.S. Pat. No.
5,477,827, the disclosure of which is hereby incorporated
herein.
[0038] If the passing duration period has not lapsed, the system
allows speed in excess of the normal maximum as described above. As
with the other threshold values, the ramp-down time is preferably
established when the ECM is calibrated, or during a subsequent
programming by authorized personnel, such as a fleet manager. In
one embodiment, the ramp-down time may be specified to be between 0
to 255 seconds.
[0039] It will be appreciated that the various different
embodiments of FIGS. 3-5 may be implemented alone or in conjunction
with each other so that, for example, the system may limit
requested speed to the normal maximum plus an established passing
speed increment, issue a warning to the driver when the passing
duration period is less than an established warning period, and/or
gradually reduce the requested additional speed when the passing
duration has lapsed.
[0040] To reduce the risk of tampering, it may be required that the
time of the next reset interval, along with the current remaining
duration value be periodically stored in memory. Whenever the
system clock is changed to a time which prompts reinitialization of
the reset interval, the then current value of the duration interval
could be maintained until completion of the next reset interval.
For example, assume the system establishes the reset interval at
four hours and the passing duration interval at 30 minutes. If the
vehicle has been operated so that there is one hour remaining in
the current reset interval and there is six minutes of passing
speed duration time remaining, and the system clock is moved ahead
two hours, a new four hour reset interval is initiated, but only
six minutes of passing duration time is allocated for the next four
hour interval. Thereafter the passing speed duration will be
reestablished to 30 minutes at the beginning of each subsequent
reset interval. In this manner, an operator cannot easily obtain a
full passing speed duration of 30 minutes by simply resetting the
clock to the next four hour interval.
[0041] It will also be appreciated that the system of the present
invention may record various data associated with the use of this
feature for later review by the operator, fleet manager, vehicle
owners, or service personnel. For example, the system may record
cumulative time spent in "passing speed", cumulative distance
traveled in "passing speed", and the time and frequency of any
warnings issued. This information may be downloaded with other
engine historical information using interface 42 or other known
methods and apparatus.
[0042] Again, the particular order of operations illustrated is for
convenience only. Preferably, one or more of the
computations/decisions illustrated are made essentially
concurrently and do not depend on the result of other operations
except where necessary as will be recognized by one of ordinary
skill in the art.
[0043] Thus, the present invention provides a system and method for
allowing a vehicle operator the flexibility to operate his/her
vehicle at a speed exceeding the normal vehicle speed limit to
allow the driver to perform normal passing, and to provide
additional speed in limited emergencies, while limiting this
capability so as not to frustrate vehicle operation and safety
goals attained by normally established vehicle speed limits.
[0044] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
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.
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