Clutch Torque Trajectory Correction to Provide Torque Hole Filling During a Ratio Upshift
First Claim
1. A powertrain having a source of input torque and a multiple ratio power transmission with oncoming and off-going friction elements, and a shift controller configured for correcting an estimated oncoming friction element torque during a torque phase of a ratio shift using a measured powertrain operating variable whereby an increasing torque for the oncoming friction element is achieved with minimal torque transients during the torque phase.
1 Assignment
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Accused Products
Abstract
A control system and method for controlling a multiple gear ratio automatic transmission in a powertrain for an automatic transmission having pressure activated friction torque elements to effect gear ratio upshifts. The friction torque elements are synchronously engaged and released during a torque phase of an upshift event as torque from a torque source is increased while allowing the off-going friction elements to slip, followed by an inertia phase during which torque from a torque source is modulated. A perceptible transmission output torque reduction during an upshift is avoided. Measured torque values are used during a torque phase of the upshift to correct an estimated oncoming friction element target torque so that transient torque disturbances at an oncoming clutch are avoided and torque transients at the output shaft are reduced.
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Citations
15 Claims
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1. A powertrain having a source of input torque and a multiple ratio power transmission with oncoming and off-going friction elements, and a shift controller configured for correcting an estimated oncoming friction element torque during a torque phase of a ratio shift using a measured powertrain operating variable whereby an increasing torque for the oncoming friction element is achieved with minimal torque transients during the torque phase.
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2. A powertrain having a source of input torque and a multiple ratio power transmission with oncoming friction elements and off-going friction elements for effecting ratio upshifts, and a shift controller configured for:
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increasing input torque during a torque phase of an upshift; estimating oncoming friction element target torque during the torque phase of the upshift; measuring an actual transmission operating variable for a torque transmitting element of the transmission; and correcting estimated oncoming friction element torque using the measured variable whereby an increasing torque for the oncoming friction element is achieved with minimal torque transients during the torque phase. - View Dependent Claims (3, 4, 5, 6, 10, 14)
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7. A powertrain having a torque input shaft and a multiple ratio power transmission mechanism with an oncoming torque transmitting friction element and an off-going torque transmitting friction element for effecting ratio upshifts during torque delivery to a torque output shaft, and a shift controller configured for:
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increasing torque input at a controlled rate during a torque phase of a ratio upshift; estimating oncoming friction element torque during the torque phase of the upshift; controlling torque input to achieve a desired off-going friction element slip; measuring actual friction element torque for the torque transmitting friction elements of the transmission; and correcting estimated oncoming friction element torque using the measured torque whereby a target torque for the oncoming friction element is achieved with minimal torque transients during the torque phase. - View Dependent Claims (9, 11, 12, 15)
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8. A method for controlling an oncoming friction element and an off-going friction element in a multiple ratio transmission during a torque phase of an upshift, the method comprising the steps of:
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increasing a transmission input torque during the torque phase; choosing a desired output shaft torque and a desired off-going friction element torque; controlling input torque to achieve desired off-going friction element slip; measuring oncoming and off-going friction element torque; and calculating an oncoming feed-forward friction element torque as a function of chosen output shaft torque and measured off-going friction element torque followed by an inertia phase of the upshift.
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13. A method for controlling upshifts in a powertrain having a torque input shaft and a multiple ratio power transmission with an oncoming friction element and an off-going friction elements for effecting ratio upshifts during torque delivery from a torque input shaft to a torque output shaft, the method comprising the steps of:
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choosing a desired output shaft torque and a desired input shaft slip torque; calculating a target input torque during a torque phase of an upshift; calculating an oncoming friction element torque target as a function of a change in off-going friction element torque during the torque phase and a change in torque of the input shaft and ramping oncoming clutch torque to the torque target; measuring actual oncoming friction element torque during the torque phase and calculating a feedback correction based on measured oncoming friction element torque; and ramping input torque toward the target input torque.
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Specification