Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Traffic analysis or control of aircraft
Reexamination Certificate
2000-03-10
2001-07-10
Dolinar, Andrew M. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Traffic analysis or control of aircraft
C701S103000, C477S054000, C477S113000, C477S181000, C477S073000, C477S001000
Reexamination Certificate
active
06259986
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention relates to a method for controlling a vehicle powertrain having a torque sensor by adjusting torque in response to the information provided by the torque sensor.
BACKGROUND OF THE INVENTION
Vehicles driven by an internal combustion engine having a torque converter and an automatic transmission have used a torque sensor. The output of the torque sensor can be used to control engine or transmission performance. A number of approaches have been proposed for utilizing the engine torque sensor signal to achieve improved powertrain control. One such method is described in U.S. Pat. No. 5,319,555. Using the engine torque sensor output signal, vehicle driving resistance can be calculated with high precision. This information is then used to determine the most appropriate transmission gear ratio for various driving conditions such as hill climbing. In other words, transmission performance can be improved by using the output signal of the engine torque sensor.
The inventors herein have recognized a disadvantage with this approach. A typical torque sensor is usually a piezoelectric or a magnetostrictive device, which has a tendency to drift under certain operating conditions. For example, changes in ambient temperature may cause errors in the output signal values. Such errors are especially significant near very low engine torque levels such as those experienced in idle conditions. These errors lead to degraded engine control and cause reduced fuel economy and degradation in drive feel and vehicle performance. In other words, when the output signal of the engine torque sensor is not representative of the actual engine torque, engine performance optimization is degraded.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for controlling engine torque by using the output signal of a torque sensor.
The object of the invention is achieved and disadvantages of prior approaches overcome by a method for controlling torque of a powertrain coupled to a torque sensor. The method comprises indicating when the powertrain torque is substantially zero, in response to said indication, correcting an output signal of the torque sensor, and controlling the powertrain torque in response to said corrected torque sensor output signal.
An advantage of the above aspect of the invention is that a more precise value of torque can be determined from the torque sensor and, therefore, better engine and transmission control can be achieved. These improvements will contribute to improved drive feel, vehicle performance, and fuel economy.
In another aspect of the present invention, the object is achieved and disadvantages of prior approaches overcome by a method for controlling torque of a powertrain coupled to a torque sensor where the powertrain has a torque converter. The method comprises determining desired powertrain torque based on an operator command, indicating when speed ratio across the torque converter is substantially unity, in response to said indication, correcting an output signal of the torque sensor, filtering said corrected powertrain torque sensor output signal, and controlling the powertrain in response to said filtered corrected powertrain torque sensor output signal and said desired powertrain torque.
An advantage of the above aspect of the invention is that it is possible to correct offsets in the torque sensor. Further, by filtering these corrections, it is possible to prevent abrupt changes in measured actual torque. Thus, is it possible to provide smooth powertrain control even when correcting for offsets. These improvements will further contribute to improved drive feel, vehicle performance, and fuel economy.
Other objects, features and advantages of the present invention will be readily appreciated by the reader of this specification.
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Dolinar Andrew M.
Ford Global Technologies Inc.
Russell John D.
Voutyras Julia
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