Closed loop computer control for an automatic transmission
First Claim
1. A method for controlling during a drive ratio change the operation of a power source and a transmission, which driveably connects the power source and the drive wheels of a motor vehicle, has a gearset capable of producing multiple drive ratios and a clutch engaged and disengaged to change the drive ratio produced by the transmission, the power source producing torque whose magnitude varies in accordance with a signal supplied to the power source control unit, comprising:
- producing a commanded power source speed corresponding to the drive ratio to which the transmission will be shifted;
producing a commanding clutch pressure from the power source torque error derived from the difference between the commanded power source speed and the actual power source speed;
controlling the torque transmitted by the clutch by supplying pressure to the clutch in accordance with the clutch pressure error derived from the difference between the commanded clutch pressure and the actual clutch pressure;
producing a commanded drive wheel torque corresponding to the drive wheel speed demanded by the vehicle operator;
producing a commanded power source torque from the motor type error derived from the difference between the commanded drive wheel torque and the actual drive wheel torque; and
controlling the torque produced by the power source by supplying to the power source control unit a compensated commanded power source error signal derived from the difference between the commanded power source torque and the actual power source torque.
1 Assignment
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Accused Products
Abstract
In an automotive vehicle having an automatic transmission that driveably connects a power source to the driving wheels, a method to control the application of hydraulic pressure to a clutch, whose engagement produces an upshift and whose disengagement produces a downshift, the speed of the power source, and the output torque of the transmission. The transmission output shaft torque and the power source speed are the controlled variables. The commanded power source torque and commanded hydraulic pressure supplied to the clutch are the control variables. A mathematical model is formulated that describes the kinematics and dynamics of the powertrain before, during and after a gear shift. The model represents the operating characteristics of each component and the structural arrangement of the components within the transmission being controlled. Next, a close loop feedback control is developed to determine the proper control law or compensation strategy to achieve an acceptably smooth gear ratio change, one in which the output torque disturbance is kept to a minimum and the duration of the shift is minimized. Then a computer algorithm simulating the shift dynamics employing the mathematical model is used to study the effects of changes in the values of the parameters established from a closed loop control of the clutch hydraulic and the power source torque on the shift quality. This computer simulation is used also to establish possible shift control strategies. The shift strategies determined from the prior step are reduced to an algorithm executed by a computer to control the operation of the power source and the transmission.
53 Citations
7 Claims
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1. A method for controlling during a drive ratio change the operation of a power source and a transmission, which driveably connects the power source and the drive wheels of a motor vehicle, has a gearset capable of producing multiple drive ratios and a clutch engaged and disengaged to change the drive ratio produced by the transmission, the power source producing torque whose magnitude varies in accordance with a signal supplied to the power source control unit, comprising:
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producing a commanded power source speed corresponding to the drive ratio to which the transmission will be shifted; producing a commanding clutch pressure from the power source torque error derived from the difference between the commanded power source speed and the actual power source speed; controlling the torque transmitted by the clutch by supplying pressure to the clutch in accordance with the clutch pressure error derived from the difference between the commanded clutch pressure and the actual clutch pressure; producing a commanded drive wheel torque corresponding to the drive wheel speed demanded by the vehicle operator; producing a commanded power source torque from the motor type error derived from the difference between the commanded drive wheel torque and the actual drive wheel torque; and controlling the torque produced by the power source by supplying to the power source control unit a compensated commanded power source error signal derived from the difference between the commanded power source torque and the actual power source torque. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification