Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2002-02-21
2003-04-08
Vo, Hien T. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S102000, C701S110000, C477S111000, C123S480000, C123S478000
Reexamination Certificate
active
06546329
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems for electronically controlling and managing the operation of drivetrain components including internal combustion engines and change gear transmissions, and more specifically to such systems for controlling such drivetrain components during gear shifting operations.
BACKGROUND OF THE INVENTION
Electronic control systems for managing the operation of internal combustion engines are well known and widely used in the automotive and tractor truck industries. Such systems are typically operable to control engine fueling as well as many other engine and/or vehicle operating conditions.
Designers of electronic engine control systems have heretofore devised numerous techniques for controlling engine fueling during various engine operating conditions, and one such technique is illustrated in FIG.
1
. Referring to
FIG. 1
, a prior art technique for controlling engine fueling to thereby limit engine speed during manual gear shifting operations is illustrated, wherein such a technique is commonly referred to as progressive shift control.
FIG. 1
shows a graph of engine RPM vs. vehicle speed, wherein a linear engine speed limit
10
is typically established by specifying a first engine speed limit RPM
1
at a first vehicle speed VS
1
and a second engine speed limit RPM
2
at a second vehicle speed VS
2
. The engine speed limit
10
linearly increases from RPM
1
to RPM
2
between VS
1
and VS
2
and is held constant at RPM
2
beyond VS
2
, wherein RPM
2
is typically less than rated engine speed
12
. Rated engine speed, also known as governed engine speed, is defined for purposes of the present invention as the engine speed at which the engine produces an advertised engine output horsepower or torque value.
The purpose of progressive shift control is to gradually increase available engine speed (and thus more engine power) as vehicle speed increases between VS
1
and VS
2
, wherein typical values for VS
1
and VS
2
are 0.0 and 40 mph respectively. This engine speed limiting scheme accordingly encourages the vehicle operator to manually shift gears at lower engine speeds than may otherwise occur, particularly in the lower transmission gears, thereby resulting in fuel savings associated with more efficient engine operation. This feature is illustrated by gear shifting pattern
14
wherein three gear shifts are shown, each occurring at progressively increasing engine speed values.
While the progressive shift control feature
14
illustrated in
FIG. 1
achieves the goal of encouraging vehicle operators to shift at lower engine speeds, it has certain drawbacks associated therewith. For example, under high engine load operating conditions, such as when traversing a grade and/or when hauling a heavily loaded trailer, providing a hard limit
10
on available engine speed can hinder the drivability of the vehicle. One example of such hindered drivability is shown by shifting pattern
16
of
FIG. 1
, which illustrates the effect on the shifting pattern
14
of a steep grade encountered by the same vehicle. Under such operating conditions, the limit
10
on engine speed causes the vehicle operator to shift sooner than would otherwise be preferred and the effect of the steep grade causes additional loss in both engine speed and vehicle speed over that of shifting pattern
14
. Under severe operating conditions, the vehicle may accordingly have insufficient momentum to justify a shift to the next higher gear, thereby defeating the purpose of engine speed limit
10
. What is needed under such conditions, is the ability to increase engine speed up to rated engine speed
12
before shifting to the next higher gear as illustrated by shifting pattern
18
in
FIG. 1
, wherein engine speed following a shift should ideally remain above a peak torque engine RPM
15
. This scenario would improve grade climbing performance as well as the likelihood of successfully completing the shift, wherein both of these improvements result from additional kinetic energy present in the vehicle prior to the shift and from the increased engine power and response after the shift. However, while sufficient engine speed for grade climbing and the like is necessary, there is also a need for limiting engine output conditions during such grade climbing or other operation so as to maintain fuel efficient engine operation.
What is therefore needed is a system for controlling drivetrain components, which may include an internal combustion engine and a change gear transmission, to thereby achieve desired fuel economy goals while also allowing for additional engine output only when the need therefore legitimately exists.
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 a vehicle drivetrain comprises a memory having stored therein an engine output characteristics map for an internal combustion engine and a number of fuel consumption contours associated with the map, and means for establishing a region of the engine output characteristics map wherein engine operation is undesirable, the region defining a first border as a function of at least one of the fuel consumption contours and a second border intersecting the first border.
In accordance with another aspect of the present invention, a method of controlling a vehicle drivetrain comprises the steps of establishing in memory an engine output characteristics map for an internal combustion engine, defining a number of fuel consumption contours associated with the engine output characteristics map, defining a first border relative to the engine output characteristics map as a function of at least one of the fuel consumption contours, and defining a second border relative to the engine output characteristics map and intersecting the first border, the first and second borders defining a region of the engine output characteristics map wherein engine operation is undesirable.
In accordance with yet another aspect of the present invention, a system for controlling a vehicle drivetrain comprises a memory having stored therein an engine output characteristics map, a region thereof of undesirable engine operation and a number of fuel consumption contours associated with the engine characteristics map, the region having a first border defined as a function of at least one of the number of fuel consumption contours and a second border intersecting the first border, and a control computer controlling engine operation according to the engine output characteristics map while maintaining or encouraging engine operation outside the region.
In accordance with still another aspect of the present invention, a method of controlling a vehicle drivetrain comprises the steps of providing an engine output characteristics map for an internal combustion engine, providing a number of fuel consumption contours associated with the map defining a region of the engine output characteristics map of undesirable engine operation, the region having a first border defined as a function of at least one of the fuel consumption contours and a second border intersecting the first border, and controlling engine operation according to the engine output characteristics map while maintaining or encouraging engine operation outside the region.
In accordance with a further aspect of the present invention, a system for controlling a vehicle drivetrain comprises a memory having stored therein an engine output characteristics map of an internal combustion engine and a contour associated with the map extending from a low engine load value to a high engine load value thereof, means for determining at least one engine operating parameter, and a control computer responsive to the at least one engine operating parameter to control shift points of a transmission coupled to the engine as the at least one engine operating parameter approaches the contour.
In accordance with yet a further aspect of the present invention, a metho
Barnes & Thornburg
Cummins Inc.
Vo Hien T.
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