Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-03-24
2001-03-13
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S091000
Reexamination Certificate
active
06202021
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems for controlling road speed of a vehicle driven by an internal combustion engine, and more specifically to such systems for controlling maximum road speed under manual throttle control of the engine.
BACKGROUND OF THE INVENTION
Road speed governing systems are generally known in the automotive and heavy duty truck industries. Such systems are typically computer controlled wherein a control computer is responsive to a present vehicle speed signal to limit engine fueling signals to thereby limit vehicle speed to a programmed maximum road speed limit. An example of a portion of one prior art engine and road speed governing control system is illustrated in FIG.
2
.
Referring to
FIG. 2
, the prior art engine and road speed governing control system includes a control computer
5
, typically referred to as an Engine Control Module (ECM), Engine Control Unit (ECU) or the like. Control computer
5
receives engine/vehicle operating signals from a number of sensors and other electrical components such as, for example, an accelerator pedal signal via signal path
24
, an engine speed signal via signal path
32
and a vehicle speed signal via signal path
36
. Control computer
5
is responsive to at least the foregoing signals to produce one or more fuel command signals, via signal path
58
, for controlling a fuel system of an internal combustion engine.
Control computer
5
includes a fuel request calculation block
80
receiving the accelerator pedal signal via signal path
24
, wherein block
80
is operable to compute an engine speed reference value ESREF therefrom and provide the ESREF value to a summing node &Sgr;. The summing node &Sgr; subtracts the ESREF signal from the engine speed signal supplied thereto via signal path
32
, and produces a corresponding error signal which is supplied to an engine speed governor
82
. Gov
82
may be any one of a variety of known engine speed governors such as a PID, all-speed or other known engine speed governor. Gov
82
produces an engine speed governor fuel command signal ESG FUEL, which corresponds to engine fueling conditions required to achieve the desired engine speed, and supplies the ESG fuel value to one input of a MIN block
84
.
Control computer
5
further includes a road speed governor (RSG)
86
which includes a max road speed block
88
representing a programmed maximum road speed value, RSREF, stored within control computer
5
. The maximum road speed value RSREF is supplied to a road speed limiter (RSL)
90
which also receives the vehicle speed signal supplied thereto via signal path
36
. RSL
90
produces a road speed governor fuel command signal RSG FUEL, and supplies the RSG fuel value to a second input of MIN block
84
. The output of MIN block
84
provides the fuel command signal, FUEL COMMAND, on signal path
58
.
In operation, RSL
90
is operable to compare the vehicle speed signal with RSREF, and if vehicle speed is less than RSREF, RSL
90
produces a maximum fuel command as the RSG FUEL value on signal path
92
. In this case, MIN block
84
is correspondingly operable to produce the ESG FUEL value on signal path
58
as the commanded fueling signal FUEL COMMAND. If, on the other hand, the vehicle speed signal exceeds RSREF, RSL
90
produces an RSL FUEL command as the RSG FUEL value on signal path
92
, wherein the RSL FUEL command corresponds to engine fueling conditions in which actual vehicle speed is limited to the maximum road speed value RSREF. Since RSG FUEL will typically be less than ESG FUEL under such road speed limiting conditions, the FUEL COMMAND signal produced by MIN block
84
will accordingly be equal to RSG FUEL.
While road speed governing systems such as that just described have been extensively used in the automotive and heavy duty truck industries, they have certain drawbacks associated therewith. For example, while cruise control systems are often used by drivers as a technique for automatically limiting vehicle speed to a desired road speed, no such mechanism exists for limiting vehicle speed to a desired road speed under manual fueling conditions (typically via an accelerator pedal). As another example, fleet owners/managers typically set the maximum road speed value at or near a maximum speed limit likely to be encountered by the vehicle. Accordingly, passing another vehicle can be difficult, and sometimes dangerous, if vehicle speed is limited to the maximum road speed value during such passing attempts. This is particularly true when both vehicles involved in a passing maneuver have identically matched maximum road speed values, since the vehicles will actually be limited to different maximum road speed values due to mechanical differences therebetween (e.g. tire wear, etc.).
What is therefore needed is an improved road speed control system which overcomes the drawbacks associated with prior art road speed governing systems. Such an improved road speed control system should ideally allow the driver to adjust the maximum road speed value within some range of road speeds, and should further allow the driver to over-ride the maximum road speed value, at least temporarily, to facilitate the passing of another vehicle.
SUMMARY OF THE INVENTION
The foregoing shortcomings of the prior art are addressed by the present invention. In accordance with one aspect of the present invention, a system for controlling road speed of a vehicle driven by an internal combustion engine comprises an accelerator pedal producing an accelerator pedal signal in response to manual actuation thereof, a fuel system associated with an internal combustion engine, the fuel system supplying fuel to the engine in accordance with a fuel signal provided thereto, means responsive to the accelerator pedal signal for producing the fueling signal, means for producing a first control signal, means for sensing vehicle speed and producing a vehicle speed signal corresponding thereto, and a road speed governor having a maximum road speed value associated therewith, the road speed governor responsive to the vehicle speed signal to limit the fuel signal to thereby limit vehicle speed to the maximum road speed value, the road speed governor responsive to the first control signal to decrease the maximum road speed value to a lesser road speed value.
In accordance with another aspect of the present invention, a method of controlling road speed of a vehicle driven by an internal combustion engine, comprising the steps of producing a fueling signal in response to manual actuation of an accelerator pedal, fueling an internal combustion engine in accordance with the fueling signal, sensing vehicle speed and producing a vehicle speed signal corresponding thereto, comparing the vehicle speed signal to a maximum road speed value, producing a fuel limiting value in response to the vehicle speed signal exceeding the maximum road speed value, limiting the fueling signal to the fuel limiting value to thereby limit vehicle road speed to the maximum road speed value, and decreasing the maximum road speed value to a lesser road speed value in response to a first control signal.
In accordance with a further aspect of the present invention, a system for controlling road speed of a vehicle driven by an internal combustion engine comprises an accelerator pedal producing an accelerator pedal signal in response to manual actuation thereof, a fuel system associated with an internal combustion engine, the fuel system supplying fuel to the engine in accordance with a fuel signal provided thereto, means responsive to the accelerator pedal signal for producing the fueling signal, means for producing a control signal, means for sensing vehicle speed and producing a vehicle speed signal corresponding thereto, and a road speed governor having a maximum road speed value associated therewith, the road speed governor responsive to the vehicle speed signal to limit the fuel signal to thereby limit vehicle speed to the maximum road speed value, the road speed governor responsive to the con
Kresse John P.
Niehus W. Patrick
Baker & Daniels
Cummins Engine Company, Inc.
Nguyen Tan
LandOfFree
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