# US 5,343,782 A · Anti-flare method using offgoing slip speed and rate of change of slip-speed to determine pressure compensation for incoming clutch > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,343,782 A - Document ID: US5343782A - Status: Granted - Kind: A - Application number: 07/936,994 - Filed: 1992-08-31 - Granted: 1994-09-06 - Earliest claimed: 1992-08-31 - Assignees: General Motors Corporation - Inventors: Fereydoon Jamzadeh - Web page: https://patentgrep.com/patent/US5343782A ## CPC - F16H 61/061: {using electric control means} - B60W 2050/001: {Proportional integral [PI] controller} - B60W 2050/0012: {Feedforward or open loop systems} - B60W 2050/0022: {Gains, weighting coefficients or weighting functions} - F16H 59/48: Inputs being a function of acceleration - F16H 2059/385: {Turbine speed} - F16H 2059/467: {of torque converter} - F16H 2061/0078: {Linear control, e.g. PID, state feedback or Kalman} - F16H 2061/0477: {by suppression of excessive engine flare or turbine racing during shift transition} - F16H: GEARING - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT ## Abstract In a computer-based control, pressure is progressively decreased in an off-going clutch for gradual release while pressure is progressively increased in an on-coming clutch. Positive off-going clutch slip and the rate of slip change are monitored to detect the onset of turbine flare. A control calculates a compensation pressure which is added to the on-coming clutch pressure to reduce the slip and thus the flare. The control calculates a term proportional to slip and an integral term when the slip and slip rate are positive. When the slip rate goes negative, the control calculates a negative integral term. All the calculated terms are combined to produce the compensation pressure value. ## Claims ### Claim 1 In a control for an automatic transmission having a turbine driving an output shaft through a gearset which achieves an upshift by controllably releasing an off-going torque transmitting device for a current speed ratio and controllably applying a fluid operated on-coming torque transmitting device for a lower speed ratio by a commanded on-coming pressure, wherein the turbine is subject to flare if the on-coming pressure is insufficient when the off-going torque transmitting device is released, a method of controlling the turbine flare comprising the steps of: determining a slip speed across the off-going torque transmitting device, wherein the slip speed is a measure of flare; calculating a rate of slip speed change; when the determined slip speed is positive and the calculated rate of slip speed change is positive, calculating a proportional term based on the detected slip and a first integral term based on the calculated rate of slip speed change; summing the proportional and integral terms to form a compensation term; and correcting the commanded on-coming pressure in accordance with the compensation term. ### Claim 2 (depends on 1) The method of controlling flare as defined in claim 1 including the step of calculating the first integral term only when the calculated rate of slip speed change is below a positive threshold. ### Claim 3 (depends on 1) The method of controlling flare as defined in claim 1 including the steps of: calculating a second integral term based on the calculated rate of slip speed change when the detected slip is positive and the calculated rate of slip speed change is less than a determined negative value; and including the second integral term in the compensation term. ### Claim 4 (depends on 1) The method of controlling flare as defined in claim 1 wherein the slip speed is determined periodically during a shift and wherein the step of calculating a rate of slip speed change comprises subtracting a previously determined slip speed from a currently determined slip speed. ### Claim 5 (depends on 1) The method of controlling flare as defined in claim 1 wherein an interim proportional term is calculated periodically during the shift and wherein the step of calculating the proportional term includes updating the proportional term in accordance with the interim term whenever the interim term exceeds the proportional term. ### Claim 6 In a control for an automatic transmission having a turbine driving an output shaft through a gearset which achieves an upshift by controllably releasing an off-going torque transmitting device for a current speed ratio and controllably applying a fluid operated on-coming torque transmitting device for a lower speed ratio by a commanded on-coming pressure, wherein the turbine is subject to flare if the on-coming pressure is insufficient when the off-going torque transmitting device is released, a method of controlling the turbine flare comprising the steps of: measuring turbine speed and output speed; determining a slip speed across the off-going torque transmitting device as the measured turbine speed less the product of the measured output speed and the current speed ratio, wherein the slip speed is a measure of flare; calculating a rate of slip speed change; when the determined slip speed is positive and the calculated rate of slip speed change is positive, calculating a proportional term based on the detected slip and a positive integral term based on the calculated rate of slip speed change; when the determined slip speed is above the first threshold and the calculated rate of slip speed change is less than a determined negative value, calculating a negative integral term based on the calculated rate of slip speed change; summing the proportional and the integral terms to form a compensation term; and correcting the commanded on-coming pressure in accordance with the compensation term. ### Claim 7 (depends on 6) The method of controlling flare as defined in claim 6 wherein the proportional and the positive integral terms are updated periodically when the calculated rate of slip speed change exceeds the second threshold; and the negative integral term is updated periodically when the calculated rate of slip speed change is below the determined negative value. ### Claim 8 (depends on 6) The method of controlling flare as defined in claim 6 wherein the proportional term is calculated as the product of the determined slip and a gain factor. ### Claim 9 (depends on 6) The method of controlling flare as defined in claim 6 wherein a trial term is calculated periodically as the product of the determined slip and a gain factor and the proportional term is selected as the largest periodically calculated trial term. ### Claim 10 (depends on 7) The method of controlling flare as defined in claim 7 wherein each integral term is calculated by calculating the product of the calculated rate of slip speed change and a gain factor and summing such products for a series of update periods. ### Claim 11 In a control for an automatic transmission having a turbine driving an output shaft through a gearset which achieves an upshift by controllably releasing an off-going torque transmitting device for one gear range and controllably applying an on-coming torque transmitting device for a higher gear range by a commanded on-coming pressure, wherein the turbine is subject to flare if the on-coming pressure is insufficient when the off-going torque transmitting device capacity is reduced, a method of automatically shifting the transmission comprising the steps of: disengaging the off-going torque transmitting device by reducing its pressure according to an off-going pressure command having a progressively decreasing value to complete such disengagement; engaging the on-coming torque transmitting device by successively supplying it with hydraulic pressure for a predefined fill period and thereafter controlling such pressure to effect a progressive engagement of the same; determining slip speed across the off-going torque transmitting device and the rate of slip speed change; when the slip is positive and the rate of slip speed change is positive, calculating a term proportional to slip and an integral term for positive slip rate; calculating a compensation term by summing the proportional and the integral terms; and correcting the commanded on-coming pressure by the amount of the compensation term. ### Claim 12 (depends on 11) The method of shifting a transmission as defined in claim 11 including the steps of: calculating an integral term for negative slip rate when the slip is positive and the rate of slip speed change is less than a determined negative value; and including the integral term for negative slip rate in the compensation term.