Adaptive pressure control method for synchronous downshifts in a multiple-ratio transmission
First Claim
1. An adaptive control method for an electronic ratio shift controller for a multiple-ratio transmission, the transmission comprising gear elements defining plural torque flow paths between a torque input shaft and a torque output shaft, and pressure-actuated friction elements selectively establishing a power-off downshift in gear ratio as an oncoming friction element and an offgoing friction element are applied and released, the downshift having adaptive shift characteristics including pressure boost time as pressure at the oncoming friction element is boosted and starting pressure for the oncoming friction element at the beginning of a ratio change is increased, the control method comprising the steps of:
- monitoring measured operating conditions during a current power-off downshift; and
adjusting the adaptive shift characteristics for a subsequent downshift as determined by the measured operating conditions, whereby power-off downshift quality is improved;
the step of adjusting the adaptive shift characteristics being executed in a predetermined order of priority to achieve shift smoothness in a reduced power-off downshift time.
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Accused Products
Abstract
An adaptive pressure control method for synchronous downshifts in an automatic transmission that uses pressure actuated friction elements. The method uses characteristic parameters that determine downshift quality for both power-on downshifts and power-off downshifts. Selected measured variables are monitored to detect changes in the parameters. Adjustments for the friction elements are made in response to changes in the measured variables.
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Citations
34 Claims
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1. An adaptive control method for an electronic ratio shift controller for a multiple-ratio transmission, the transmission comprising gear elements defining plural torque flow paths between a torque input shaft and a torque output shaft, and pressure-actuated friction elements selectively establishing a power-off downshift in gear ratio as an oncoming friction element and an offgoing friction element are applied and released, the downshift having adaptive shift characteristics including pressure boost time as pressure at the oncoming friction element is boosted and starting pressure for the oncoming friction element at the beginning of a ratio change is increased, the control method comprising the steps of:
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monitoring measured operating conditions during a current power-off downshift; and adjusting the adaptive shift characteristics for a subsequent downshift as determined by the measured operating conditions, whereby power-off downshift quality is improved; the step of adjusting the adaptive shift characteristics being executed in a predetermined order of priority to achieve shift smoothness in a reduced power-off downshift time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An adaptive control method for an electronic ratio shift controller for a multiple-ratio transmission, the transmission comprising gear elements defining plural torque flow paths between a torque input shaft and a torque output shaft, and pressure-actuated friction elements selectively establishing a power-on downshift in gear ratio as an oncoming friction element and an offgoing friction element are applied and released, the downshift having an adaptive shift characteristic comprising starting pressure for the offgoing friction element at the beginning of a ratio change, the control method comprising the steps of:
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monitoring measured operating conditions during a current power-on downshift; and adjusting the adaptive shift characteristic for a subsequent shift as determined by the measured operating conditions, whereby power-on downshift quality is improved; the step of adjusting shift characteristics being executed in a predetermined order of priority to achieve shift smoothness in a reduced power-on downshift time. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification