Closed loop shift quality control system
AssigneeGeneral Motors Corporation
InventorsBruce D. Lockhart, Dean E. McCulloch
Life of this patent
Estimating the term…
Abstract
The output power of an automotive powertrain including a throttled engine and a stepped ratio transmission is maintained substantially constant during upshifting of the transmission. The powertrain output torque is actively measured during shifting, and the output power of the powertrain is controlled by modulation of the engine throttle position and spark timing, and the transmission clutch apply pressures.
Claims5
In a motor vehicle powertrain including a throttled spark ignition internal combustion engine adapted to drive a powertrain output shaft through a shiftable ratio transmission having first and second elements defining first and second torque and speed ratios between the engine and the powertrain output shaft, the second torque ratio providing less torque advantage than the first torque ratio, and the second speed ratio providing greater speed advantage than the first speed ratio, and a torque transmitting device associated with each of said first and second elements selectively operable to activate the respective speed and torque ratios, and a controller normally effective to set the timing of the engine spark ignition in accordance with engine operating parameters, and to set the position of the engine throttle in accordance with a measured powertrain parameter so as to maintain the powertrain power output at a level selected by the motor vehicle operator, a method of operation which maintains the powertrain power output at the selected level during shifting from said first speed and torque ratios to said second speed and torque ratios, the method comprising the steps of:
- detecting an operating condition in which the first speed and torque ratios of the transmission are activated and in which the engine would be capable of driving the powertrain output shaft at the power level selected by the operator with the second torque ratio activated, and in response to such detection:
- increasing the position of the engine throttle to produce an engine torque increase in relation to the decrease in torque advantage between the first and second torque ratios, and concurrently retarding the timing of the engine spark ignition to counter the increase in torque due to the increase in throttle position, thereby to prepare the engine for spark timing control of its output torque while maintaining the powertrain output power substantially at the level selected by the operator;
- progressively increasing the torque capacity of the torque establishing device associated with said second elements, and decreasing the torque capacity of the torque establishing device associated with said first elements;
- advancing the timing of the engine spark ignition in accordance with a measured powertrain parameter to maintain the powertrain output power substantially at the level selected by the operator, whereby the engine torque increases in the amount necessary to counter the decreased torque advantage of said second torque ratio;
- and
- returning the engine throttle position to the normally effective setting and controlling the torque capacity of the torque transmitting device associated with said second elements in accordance with a measured powertrain parameter when the engine speed changes in response to increased torque capacity of the torque transmitting device associated with the second elements, so as to maintain the powertrain output power at the level selected by the operator while the speed ratio of the transmission changes from the first speed ratio to the second speed ratio.
In a motor vehicle powertrain including a throttled spark ignition internal combustion engine adapted to drive a powertrain output shaft through a shiftable ratio transmission having first and second elements defining first and second torque and speed ratios between the engine and the powertrain output shaft, the second torque ratio providing less torque advantage than the first torque ratio, and the second speed ratio providing greater speed advantage than the first speed ratio, and a torque transmitting device associated with each of said first and second elements selectively operable to activate the respective speed and torque ratios, and a controller normally effective to set the timing of the engine spark ignition in accordance with engine operating parameters, and to set the position of the engine throttle in accordance with a measured powertrain parameter so as to maintain the powertrain power output at a level selected by the motor vehicle operator, a system for maintaining the powertrain power output at the selected level during shifting of the transmission from said first speed and torque ratios to said second speed and torque ratios, the system comprising:
- means including control means for detecting an operating condition in which the first speed and torque ratios of the transmission have been activated and in which the engine would be capable of driving the powertrain output shaft at the power level selected by the operator with the second torque ratio activated, the control means being effective in response to such detection to initiate activation of the torque transmitting device associated with the second elements and deactivation of the torque transmitting device associated with the first elements;
- the control means being further effective in a preparatory phase wherein the torque transmitting device associated with the second elements is not yet ready for engine torque transmission, for (1) increasing the position of the engine throttle to produce an engine torque increase in relation to the reduction in torque advantage between the first and second torque ratios, and (2) retarding the timing of the engine spark ignition to counter the increase in torque due to the increase in throttle position, thereby preparing the engine for spark timing control of its output torque while maintaining the powertrain output power substantially at the level selected by the operator;
- the control means being further effective in a torque phase wherein the torque transmitting device associated with the second elements begins transmitting engine torque without decreasing the engine speed, and the torque ratio of the transmission decreases from the first torque ratio to the second torque ratio, for advancing the timing of the engine spark ignition in accordance with a measured powertrain parameter to maintain the powertrain output power substantially at the level selected by the operator, whereby the engine torque increases in the amount necessary to counter the decreased torque advantage of said second torque ratio;
- and
- the control means being further effective in an inertia phase wherein the engine speed decreases in response to the transmission of engine torque by the torque transmitting device associated with the second elements, and the speed ratio of the transmission increases from the first speed ratio to the second speed ratio, for (1) returning the engine throttle position to the normally effective setting, (2) controlling the torque capacity of the torque transmitting device associated with said second elements in accordance with a measure of the powertrain output power to maintain the powertrain output power at the level selected by the operator
Dependencies are inferred from the claim text.