Clutch Torque Trajectory Correction to Provide Torque Hole Filling during a Ratio Upshift

• US 20140287872A1
• Filed: 06/04/2014
• Published: 09/25/2014
• Est. Priority Date: 06/08/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Teslak, Christopher John, Pietron, Gregory Michael, Tseng, Hongtei Eric, Fujii, Yuji, Fodor, Michael Glenn, Yanakiev, Diana, Lee, Seung-Hoon
• Granted Patent: US 9,260,102 B2
• Time in Patent Office: Days
• US Class Current: 477/79
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/115 with planetary gears
• CPC Class Codes: B60W 2050/0008 Feedback, closed loop systems or details of feedback error signal
• CPC Class Codes: B60W 2050/0043 Signal treatments, identification of variables or parameters, parameter estimation or state estimation
• CPC Class Codes: B60W 2510/0275 Clutch torque
• CPC Class Codes: B60W 2510/105 Output torque
• CPC Class Codes: B60W 2710/025 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: B60W 2710/027 Clutch torque
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: B60W 50/06 Improving the dynamic response of the control system, e.g. improving the speed of regulation or avoiding hunting or overshoot
• CPC Class Codes: F16D 67/02 Clutch-brake combinations
• CPC Class Codes: F16H 2061/0462 by controlling slip rate during gear shift transition
• CPC Class Codes: F16H 59/16 Dynamometric measurement of torque
• CPC Class Codes: F16H 61/061 using electric control means

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.

Claims

1. 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:

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.

2. The powertrain set forth in claim 1 wherein the controller is configured further for determining whether measured off-going friction element torque is less than a predetermined threshold and releasing the off-going clutch if measured off-going friction element torque is less than the threshold;

and

repeating the correction of estimated oncoming friction element torque if the off-going friction element torque is not less than the threshold.

3. The powertrain set forth in claim 1 including at least two torque sensors for measuring friction torque values for off-going and oncoming friction elements, one sensor being adapted to measure actual input torque and the other torque sensor being adapted to measure friction element torque of one of the friction elements;

the controller having memory registers with a stored transfer function for each friction element;

the transfer function being precalibrated with a functional relationship between a sensor actuator displacement and friction element torque;

the one sensor being adapted to measure a sum of torque input for each friction element;

the other sensor being adapted to measure torque output of one of the friction elements, whereby torque output of the other friction element is equal to a difference between torque measured by the one sensor and the torque measured by the other torque sensor.

4. 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:

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.

5. The method set forth in claim 4 wherein the step of increasing torque input comprises:

controlling the engine to achieve an increasing torque input and a controlled slip of the off-going friction element during the torque phase.

6. The method set forth in claim 4 wherein the step of correcting an estimated oncoming friction element torque is followed by a determination of whether a measured torque of the off-going friction element is less than a predetermined threshold and releasing the off-going clutch if the measured off-going friction element torque is less than the threshold, and

repeating the steps for correcting an estimated oncoming friction element torque if the off-going friction element torque is greater than the threshold.

7. The method set forth in claim 4 wherein the step of correcting estimated oncoming friction element torque includes computing a correction in a closed loop fashion using measured off-going friction element torque as a feedback variable.

8. 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:

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.