Note: Descriptions are shown in the official language in which they were submitted.
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FUEL ECONOMY SYSTEM AND METHOD FOR A VEHICLE
FIELD OF THE INVENTION
The present invention relates to a fuel economy system and method for a
vehicle, and is more particularly concerned with a fuel economy system and
method for a vehicle which regulate the power output of an engine of a
vehicle,
and thereby the fuel consumed thereby, based on a mass of a load carried by
the vehicle.
BACKGROUND OF THE INVENTION
Systems and methods for limiting the power output of an engine, for fuel
economy and other purposes are well known in the art. For example, United
States patent number 6,052,644, issued to Murakami et al. on April 18, 2000
teaches an device and a method for limiting the vehicle speed in which the
apparatus judges a vehicle speed limit traveling period when a vehicle speed
signal is equal to or greater than a vehicle speed limit value, to calculate a
corrected depressing stroke signal by a control gain based on a deviation
value
between the vehicle speed signal and the vehicle speed limit value so that the
deviation value becomes smaller to output to an engine control device, and
judges an accelerated traveling period, when the vehicle speed signal is
smaller
than the vehicle speed limit value and the corrected depressing stroke signal
is
larger than a depressing stroke signal, to output the depressing stroke signal
to
the engine control device. However, disadvantageously, such devices as that
disclosed by Murakami only regulates the speed of the vehicle by taking into
account the actual speed of the vehicle and correcting the speed of the motor
only after the speed of the vehicle has surpassed or fallen below the vehicle
speed limit value, and are thus not ideal for purposes of economizing fuel.
Further, such devices do not take into account the mass of a load carried by
the
vehicle.
Japanese patent application publication number 05221251, filed on
February 12, 2002 by Komatsu Ltd. with Hattori Masaharu named as inventor,
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discloses another device for limiting the output of an engine, and thereby the
speed, of a dump truck which obviates some of these disadvantages by taking
into account the mass of a load carried by the dump truck using a pressure
sensor. However, the system taught by Komatsu is above all conceived for
preventing overloading of the dump truck and damage to a surface upon which
the dump truck operates. Further, the device taught by Komatsu is complicated
in that it requires connection to a multiplicity of components, including a
transmission shifting device, rotational speed sensors for the motor, and to a
pressure sensor.
Accordingly, an improved fuel economy system and method for a vehicle is
required.
SUMMARY OF THE INVENTION
It is therefore a general object of the present invention to provide an
improved
fuel economy system and method that limits the power output of an engine of a
vehicle based on the mass of a load carried by the vehicle.
An advantage of the present invention is that the fuel economy system and
method provided thereby does not require modification of the engine control
unit
of the vehicle.
Another advantage of the present invention is that the fuel economy system and
method provided thereby provides fuel economy transparently and automatically
based on the mass of the load carried by the vehicle without express
intervention or knowledge of the driver of the vehicle so as to significantly
reduce the effect of bad drivers on fuel consumption.
According to a first aspect of the present invention, there is provided a fuel
economy system connectable to a throttling means of a vehicle and to an
engine control unit connected to an engine of the vehicle, the throttling
means
generating an unmodified throttling signal having a throttling signal voltage
in an
unmodified throttling signal voltage range between a minimum throttling signal
voltage and an unmodified maximum throttling signal voltage in response to a
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throttling input between a minimum throttling input and a maximum throttling
input received by the throttling means, the engine control unit increasing and
decreasing an engine power output of the engine, and thereby an amount of
fuel consumed thereby, as the throttling signal voltage and throttling input
both
respectively increase and decrease, the system comprises:
- a sensor for sensing a mass of a load carried by the vehicle; and
- a signal control unit connected to the sensor and connectable to the
throttling means and the engine control unit, the signal control unit, when
the mass sensed by the sensor is within a pre-determined mass range
below a pre-determined load mass value, reducing a range of the engine
power output for the throttling input from an unmodified engine power
output range having a minimum engine power output corresponding to
the minimum throttling input and an unmodified maximum engine power
output corresponding to the maximum throttling input to a modified
engine power output range between the minimum engine power output
and a modified engine power output corresponding to the maximum
throttling input and below the unmodified throttling input, thereby
gradually reducing the engine power output, compared to the unmodified
engine power output, for the throttling input and the amount of fuel
consumed when the mass is in the pre-determined mass range.
In another aspect of the present invention, there is provided a fuel economy
method for a vehicle having a throttling means and an engine control unit
connected to an engine of the vehicle, the throttling means generating an
unmodified throttling signal having a throttling signal voltage in an
unmodified
throttling signal voltage range between a minimum throttling signal voltage
and
an unmodified maximum throttling signal voltage in response to a throttling
input
between a minimum throttling input and a maximum throttling input received by
the throttling means, the engine control unit increasing and decreasing an
engine power output of the engine, and thereby an amount of fuel consumed
thereby, as the throttling signal voltage and throttling input both
respectively
increase and decrease, the method comprises the steps of:
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a) sensing whether the mass of a load carried by the vehicle is within a pre-
determined mass range; and
b) when the mass of the load is within the pre-determined mass range
below a pre-determined load mass value, reducing a range of the engine
power output for the throttling input from an unmodified engine power
output range having a minimum engine power output corresponding to
the minimum throttling input and an unmodified maximum engine power
output corresponding to the maximum throttling input to a modified
engine power output range between the minimum engine power output
and a modified engine power output corresponding to the maximum
throttling input and below the unmodified throttling input, thereby
gradually reducing the engine power output and the fuel consumed,
compared to the unmodified engine power output and fuel consumed, as
the throttling input approaches the maximum throttling input when the
mass is in the pre-determined mass range.
Other objects and advantages of the present invention will become apparent
from a careful reading of the detailed description provided herein, with
appropriate reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects and advantages of the present invention will become better
understood with reference to the description in association with the following
Figure, wherein:
Figure 1 is a schematic view of a fuel economy system in accordance with an
embodiment of the invention connected to a throttling means and engine control
unit of a vehicle; and
Figure 2 is a flow chart of a fuel economy method in accordance with an
embodiment of the invention connected to a throttling means and engine control
unit of a vehicle.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the annexed drawings the preferred embodiments of the
present invention will be herein described for indicative purpose and by no
means as of limitation.
5 Reference is now made to Figures 1 and 2. Figure 1 shows a schematic view
of
a fuel economy system, shown generally as 10, in accordance with an
embodiment of the invention connected to a throttling means 12 and engine
control unit (ECU) 14 of a vehicle 20. Figure 2 shows a fuel economy method,
shown generally as 100, in accordance with an embodiment of the invention
and which is deployed with the system shown in Figure 1.
The system 10 consists of a signal control unit (SCU) 16 and at least one
sensor (SN) 18 to which the SCU 16 is connected. The SN 18 is connected to
the vehicle or to a trailer 26 connected to the vehicle and senses, i.e.
measures
or determines, the mass of a load 24 carried by the vehicle 20 or on the
trailer
26 connected thereto at step 102 of method 100. The SN 18 transmits the
mass of the load 24 determined thereby, as a mass signal, to the SCU 16,
which determines, at step 104, whether the mass of the load 24 is within one
or
more pre-determined mass ranges, below a pre-determined load mass value,
such as the manufacturer maximum rated load mass value for the vehicle.
Alternatively, the SN 18 may simply transmit a mass signal to the SCU 16
indicating whether the mass of the load 24 is within one or more pre-
determined
mass ranges, in which case steps 102 and 104 of method 100 are combined.
The SCU 16 is, in turn, connectable to the, typically pre-existing, throttling
means 12 on the vehicle 20 and the ECU 14, generally also pre-existing, of the
vehicle 20. The throttling means 12 typically has a throttling input
mechanism,
such as pedal or the like, operated by the driver of the vehicle 20 and by
which
the throttling means receives a throttling input within a throttling input
range
defined by a minimum throttling input and a maximum throttling input. In
response to the throttling input, the throttling means generates an unmodified
throttling signal having a throttling signal voltage which increases and
decreases within an unmodified throttling signal range defined by a minimum,
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and possibly null, throttling signal voltage and an unmodified maximum
throttling
signal voltage in response to, respectively, increases and decreases in the
throttling input within the throttling input range. When the system 10 is not
deployed or installed in the vehicle 20, in which case the ECU 14 is typically
directly connected to the throttling means 12, or when the mass of the load 24
detected by the SN 18 is determined at step 104 to be outside, and typically
above, the pre-determined mass range, that is above the pre-determined load
mass value, the ECU 14 receives the throttling signal, at step 108, as an
unmodified throttling signal from the throttling means 12. The ECU 14, in
response to the unmodified throttling signal, increases and decreases the
engine power output (referred to as engine output hereinafter) of engine 22
within an unmodified engine output range defined by a minimum, or possibly
null, engine output and an unmodified maximum engine output as the throttling
signal voltage respectively increases and decreases, within the unmodified
throttling signal range. Accordingly, the minimum engine output corresponds to
the minimum throttling signal which corresponds to the minimum throttling
input.
Similarly, the unmodified maximum engine output corresponds to the
unmodified maximum throttling signal which corresponds to the maximum
throttling input. As is well known in the art, the amount of fuel consumed by
the
vehicle increases and decreases as the output of the engine 22 respectively
increases and decreases. For the purposes of this description, the engine
output of the engine 22 may be considered to be the number of revolutions
thereof in a given period of time.
To install the system 10, the SN 18 is connected to the vehicle 20, or the
trailer
26 connected to the vehicle 20, and to the SCU 16. The SCU 16 is, in turn,
connected to the output of throttling means 12 and to the input of the ECU 14
to
which the output of the throttling means 12 would be connected if the system
10
were not installed. Accordingly, when the system 10 is installed, the SCU 16
receives the unmodified throttling signal from the throttling means 12 and
provides the input to the ECU 14, i.e. the throttling signal, based upon which
the
ECU 14 controls the engine output, which in turn determines the amount of fuel
consumed thereby.
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When the system 10 is installed and actuated, the SN 18 constantly senses and
determines the mass of the load 24 carried by the vehicle 20 and transmits a
mass signal to the SCU 16 as described above for steps 102 and 104. If the
mass sensed by the SN 18 is determined at step 104 to be within a pre-
determined mass range below the pre-determined load mass value, the SCU 16
limits, i.e. reduces, the range of the engine output from the unmodified
engine
output range to a modified engine output range at step 106. To restrict the
range to the modified engine output range at step 106, the SCU 16 preferably
modifies, i.e. translates or maps, the throttling signal voltage of the
unmodified
throttling signal received from the throttling means 12 into a modified
throttling
signal using a pre-determined algorithm programmed into the SCU 16. The
modified throttling signal has a modified throttling signal voltage in a
modified
throttling signal range between the minimum throttling signal voltage and a
modified maximum throttling signal voltage which is lower than the unmodified
maximum throttling signal voltage and is transmitted by the SCU 16 to the ECU
14. Thus, when the mass sensed by the SN 18 is within the pre-determined
mass range, determined at steps 102 and 104, the ECU 14, at step 106,
receives the modified throttling signal from the SCU 16, which increases and
decreases within the modified throttling signal range between the minimum
throttling signal voltage and the modified maximum signal voltage as the
throttling input respectively increases and decreases within the throttling
input
range. Accordingly, while the mass sensed by the SN 18 is within the pre-
determined mass range, the minimum throttling signal voltage received by the
ECU 14 from SCU 16 when the throttling input is at the throttling input
minimum
remains the same at step 106 as when the SN 18 is not within the pre-
determined mass range for step 108. However, the throttling signal received by
the ECU 14 when the throttling input is at the maximum throttling input during
step 106 is modified, i.e. decreased, from the unmodified maximum throttling
signal voltage to the modified maximum throttling signal voltage. Accordingly,
when the mass sensed by the SN 18 is within the pre-determined mass range,
the maximum engine output is decreased at step 106 from the unmodified
maximum engine output to a decreased modified maximum engine output,
requiring less fuel, when the throttling input is at the maximum throttling
input
and as throttling input approaches the maximum throttling input, as compared
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when to the mass sensed by the SN 18 is not within the pre-determined mass
range, i.e. during step 108. Thus, at step 106, when the mass of the load 24
sensed by the SN 18 is within the pre-determined mass range, as determined at
steps 102 and 104, the range of the throttling signal received by the ECU 14
is
reduced from the unmodified throttling signal voltage range received by the
ECU 14, and used in step 108, to the modified throttling signal voltage range
received from the SCU 16 by the ECU 14, which reduces the engine output
range from the unmodified engine output range, used in step 108, to the
modified engine output range, whereas the throttling input range remains the
same. Accordingly, if, at step 104, the mass sensed by the SN 18 is within the
pre-determined mass range, the engine output range of the engine 22 is
automatically and transparently reduced at step 106 for the same throttle
input
range, without requiring any intervention by the driver of the vehicle. The
reduced modified engine output range of the engine 22 used at step 106
reduces, for a given period of time while the mass is in the predetermined
mass
range, the amount of fuel consumed by the engine 22, compared to the
unmodified output range used in step 108, as the throttle input approaches the
maximum throttle input as the output of the engine 22 is lowered compared to
the unmodified output range. As the mass of the load 24 is constantly sensed
by SN 24 at step 102 and measured against the predetermined mass range at
step 104, once the SCU 16 selects the modified engine output range at step
106 or unmodified engine output range at step 108, the method 100
automatically returns to step 102 and repeats.
The mass range and modified throttling signal voltage range are generally pre-
configured, i.e. programmed into the system 10 with a pre-determined
algorithm, such that the corresponding modified maximum engine output for the
modified maximum throttling signal voltage used in step 106, while reduced
compared to the unmodified maximum engine output, is sufficient to carry the
mass of the load 24 in the pre-determined mass range while still allowing the
vehicle to move at a predetermined, and commonly accepted, maximum speed,
for example between 80 and 110 km/h (kilometers per hour) or 55 to 70 mph
(miles per hour). The pre-determined algorithm applied at step 106 and by
which the unmodified throttling signal is modified into the modified
throttling
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signal may be any algorithm or function by which the voltages in the
unmodified
throttling signal range may be mapped into voltages in the modified throttling
signal range. However, preferably the algorithm will generally generate a
modified throttling signal voltage that approximates the line or curb of
voltage for
the unmodified throttling signal voltage in response to the throttling input.
However, the voltage of the modified throttling signal voltage generated by
application of the pre-determined algorithm by the SCU 16 is, preferably,
gradually decreased compared to the unmodified throttling signal voltage as
the
throttling input increases from the throttling input minimum towards the
throttling
input maximum. In other words, when the mass is in the predetermined mass
range, the difference, or gap, between the unmodified throttling signal
voltage
and the modified throttling signal voltage will increase as the throttling
input
decreases from the minimum throttling input towards the maximum throttling
input as the throttling input increases.
Typically, and referring to steps 106 and 108, the unmodified throttle signal
voltage range generated by the throttling means 12 is between the minimum
throttle signal voltage of 0 Vdc (volts, direct current) and an unmodified
maximum throttling voltage of 5 Vdc. When the mass of the load 24 is within
the pre-determined mass range, as determined at steps 102 and 104, the SCU
16, ideally, reduces the unmodified throttle signal voltage range of 0 to 5
Vdc to
a modified throttle signal voltage range between the minimum throttle signal
voltage of 0 Vdc and a modified maximum throttle signal voltage of 3.5 Vdc at
step 106. However, the system 10 may be configured for other minimum and,
both modified and unmodified, maximum throttling signal voltage values.
Further, the system 10 may be configured such that there is more than one pre-
determined mass range, each predetermined mass range having a
corresponding modified maximum throttle signal voltage and modified throttle
signal voltage range and corresponding modified engine output range and
corresponding modified maximum engine output. For example, if the mass of
the load 24 is within a first predetermined mass range of 0 and 2000 kg (or
4400 lbs), then the SCU 16 could reduce the unmodified throttle signal voltage
range of 0 to 5 Vdc to a modified throttle signal voltage range between the
minimum throttle signal voltage of 0 Vdc and a modified maximum throttle
signal
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voltage of 0 to 3.5 Vdc, reducing the engine output range accordingly. If the
mass of the load 24 is in a second pre-determined mass range between 2001
and 4000 kg (4401 and 8800 lbs)), then the SCU 16 could reduce the
unmodified throttle signal voltage range of 0 to 5 Vdc to a modified throttle
5 signal voltage range between the minimum throttle signal voltage of 0 Vdc
and a
modified maximum throttle signal voltage of 0 to 4 Vdc, which would again
reduce the engine output range accordingly, but provide a greater modified
maximum engine output than for the first pre-determined mass range so that
more power will be available to carry the additional mass of the load 24. If
the
10 mass of the load 24 is above 4000 kg (8800 lbs), as the pre-determined
load
mass value, then the SCU 16 could leave the throttle signal voltage range
unmodified, thus leaving the engine output range unmodified to provide the
full,
unmodified, power output of the engine 22 to carry the load 24.
The vehicle 20 is, typically, a truck having a trailer 26 connected thereto
and
upon which the load 24 is carried, the SN 18 being connected to the trailer 26
for sensing the mass of the load 24 carried thereon. However, the vehicle 20
could also be an automobile, tractor, or any other motorized vehicle which
carries a load 24. Further, the load 24 need not be carried on a trailer 26
attached to the vehicle 20, and can be carried directly on the vehicle 20, in
which case the SN 18 is also connected directly to the vehicle and is
configured
to detect the difference between the vehicles mass without a load 24 and the
mass with a load 24. The SN 18 may be any type of sensor or device capable
of sensing or otherwise determining the mass of the load 24. For example, the
SN 18 could be a mass sensor disposed under the load 24 for sensing and
measuring the mass thereof at step 102. The SN 18 could also, for example, be
a pressure sensor connected to the wheels underneath the load 24 and upon
which the load is carried. More specifically, the SN 18 could be a pressure
sensor 18 which measures the pressure or deformation caused by the load 24
inside the tires for the wheels upon which the load 24 is carried and which
determines, for example by calculation, the mass of the load 24 at step 102
based upon the pressure or deformation measured thereby. Similarly, the SN
18 could be a pressure sensor connected to the suspension upon which the
load 24 is carried, in which case the SN 18 could measure the deformation of
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the suspension caused by the load 24 to determine, for example by calculation,
the mass of the load at step 102 based on the deformation measured thereby.
The SN 18 could also be a sensor, such as a velocity sensor or acceleration
sensor, or other mechanism which determines, for example by calculation, the
mass of the load 24 at step 102 by measuring linear acceleration of the
vehicle
20, and specifically the effect of the mass of the load 24 on the linear
acceleration. Alternatively, the SN 18 could be a sensor, such as a velocity
sensor or acceleration sensor, for measuring angular acceleration of a
driveline
component of the vehicle and which determines the mass of the load 24 at step
102 by measuring the effect of the mass on the angular acceleration and
calculating the mass based on the effect measured. Such driveline components
could include, for example, the wheels, differential(s), hubs, as well as and
any
interconnecting shafts, of the vehicle 20.
The throttling means 12 typically has a conventional accelerator pedal, as the
throttling input device, and a transducer connected thereto, the throttling
input
being provided, and generally increased, by depression of the accelerator
pedal
and converted into the throttling signal by the transducer. Thus, the
throttling
signal voltage of the throttling signal is generally increased and decreased
as
the level of depression of the accelerator pedal respectively increases and
decreases. However, the throttling means 12 may also be a gear shift, an
accelerator lever connected to a transducer, or any other apparatus by which a
throttling input is provided by the driver of a vehicle for controlling the
output of
the engine 22 thereof and for which an electronic throttling signal is
generated in
response to the throttling input.
Optionally, the SCU 16 may also be connected to a transmission 30 of the
vehicle 20, the transmission being connected to the engine 22 and the ECU 14
and having a, preferably electronic, switch (SW) 32 connected thereto for
selecting between at least two shift schedules which control access to use of
uppermost gears when driving the vehicle 20. Typically, such schedules include
an unrestricted first shift schedule, in which the engine 22 may be shifted
without restriction, manually or automatically, into the uppermost gears which
deliver the most engine output, up to the unmodified maximum engine output,
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for the vehicle 20, and at least one additional restricted shift schedule in
which
the engine 22 may not be shifted into the uppermost gears or in which shifting
the engine 22 into the uppermost gears is restricted. In other words, the
engine
output range for the unrestricted modified engine output is the unmodified
engine output range extending from the minimum engine output and the
unmodified maximum engine output.
Conversely, for the restricted shift
schedule, the engine output is reduced to the modified engine output range
extending from the minimum engine output to the modified maximum engine
output. As the engine output is generally reduced in the restricted shift
schedules, the amount of fuel is also reduced.
Typically, when the system 10 is not installed or actuated, the driver selects
the
shift schedule by selecting a corresponding setting on the switch 32. However,
when the system 10 is installed on a vehicle 20 having a transmission 30
having
such selectable shift schedules, the SCU 16 automatically places, at step 106,
the transmission 30, engine 22 and ECU 14, in the restricted shift schedule,
by
selection thereof, when the mass detected by the SN 18 is within the
corresponding pre-determined mass range, as determined at steps 102 and
104, for which the full engine output is not required and which corresponds to
the restricted shift schedule. Thus, when the mass detected by the SN 18 is
determined at step 104 to be within the pre-determined mass range, shifting to
the uppermost gears is either automatically prevented or restricted by the SCU
16, thus limiting the engine output to the modified engine output range and
reducing the fuel consumed, without the driver having to manually select the
shift schedule using the switch 32 or other intervention thereby. Similarly,
the
SCU 16 may automatically switch, i.e. select, the engine 22 and transmission
30, and switch 32 now connected to the SCU 16, to the unrestricted shift
schedule when the mass detected by the SN 18 is sufficiently elevated above
the pre-determined load mass value that the unmodified maximum engine
output is required, i.e. outside the predetermined mass range, as determined
at
steps 102 and 104. Typically, the SCU 16 selects the restricted shift schedule
and unrestricted shift schedule by actuating, i.e. triggering, the switch 32,
typically be transmitting a signal thereto causing the switch to switch the
transmission 30, engine 22, and ECU 14 between the restricted shift schedule
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and unrestricted shift schedule. It should be noted that the automatic
switching
of the shifting schedules by the SCU 16 may be deployed either separately or
in
conjunction with adjustments to the throttling signal voltage by the SCU 16,
as
described above.
Although the fuel economy system 10 and method 100 provided by the present
invention have been described with a certain degree of particularity, it is to
be
understood that the disclosure has been made by way of example only and that
the present invention is not limited to the features of the embodiments
described
and illustrated herein, but includes all variations and modifications within
the
scope of the invention as hereinafter claimed.
