Observer-based control method for automatically shifting a manual transmission
AssigneeSouthwest Research Institute
InventorBapiraju Surampudi
Life of this patent
Estimating the term…
Abstract
A method of controlling the shifting of an automatic manual transmission is based on observer-based timing of different phases of the shift process. The observer-based control strategy includes simultaneous management of the engine throttle and transmission actuators. The torque characteristics of the transmission are also taken into consideration during control of the engine throttle, thereby minimizing shift time and wear on transmission components. The control strategy uses mathematical models called observers to monitor the value of inherent properties attributable to specific actuators and to provide signals used to implement parallel task execution.
Claims18
An observer-based control method for automatically shifting a synchromesh transmission having an input shaft connected to an engine through a disengageable clutch, an output shaft, a plurality of drive gears mounted on the output shaft , a shift fork adapted to move a selected one of a plurality of synchronizers arranged to bring a selected drive gear mounted on the output shaft to a rotational speed substantially equal to that of the output shaft prior to connecting the selected drive gear to the output shaft, a clutch actuator, and a shift fork actuator, said method comprising:
- first monitoring an intrinsic operating parameter of said clutch actuator and determining the status of clutch disengagement corresponding to an observed value of said intrinsic operating parameter of the clutch actuator to disengage said disengageable clutch when a shift decision is made;
- second monitoring at least one intrinsic operating parameter of said shift fork actuator and determining a spatial position of said shift fork corresponding to an observed value of said at least one intrinsic operating parameter of the shift fork actuator to engage a next gear in said plurality of drive gears upon synchronization;
- and
- third monitoring said intrinsic operating parameter of said clutch actuator and determining the status of clutch engagement corresponding to an observed value of said intrinsic operating parameter of the clutch actuator to engage said disengageable clutch for smooth interpolation.
An observer-based control method for automatically shifting a manual transmission on a vehicle having at least one drive wheel, an engine having a throttle, a synchromesh transmission having an input shaft connected to the engine through a disengageable clutch, an output shaft connected to the at least one drive wheel of the vehicle, a plurality of gears mounted on the output shaft for selective rotation therewith, a shift fork adapted to move one of a plurality of synchronizers adapted to bring a selected gear mounted on the output shaft to a speed matching that of the output prior to connecting the selected gear to the output shaft, a clutch actuator system, a shift fork actuator system, and a programmable transmission controller adapted to receive engine speed, vehicle speed, and gear selection input signals, monitor preselected intrinsic operating parameter of the clutch and shift fork actuator systems, and provide control signals to the engine throttle, the clutch actuator system and the shift fork actuator system, said method comprising:
- selecting a desired gear not rotationally connected to the output shaft and delivering a signal to the transmission controller correlative of the selected gear;
- providing a clutch disengage command to the clutch actuator system and controllably initiating disengagement of the clutch;
- initiating a clutch disengagement process and simultaneously assuming control of the engine throttle to reduce drive train oscillations during the process of disengaging the clutch;
- monitoring the clutch disengagement process and determining that said clutch is disengaged when a predefined value of the intrinsic operating parameter of the clutch actuator system is observed;
- disconnecting a gear that is rotationally connected to the output shaft from said output shaft;
- moving the shift fork into initial contact with a synchronizer associated with the selected gear while simultaneously throttling the engine under no load;
- observing a countershaft speed control process in which friction contact between the synchronizer and said selected gear is monitored and the engine throttle is simultaneously controlled to bring the selected gear and the output shaft to the same speed;
- moving the synchronizer into rotationally fixed relationship with said selected gear and connecting the selected gear to the output shaft in response to observing that said countershaft and said output shaft are at the same speed;
- initiating a clutch engagement process and simultaneously controlling the engine throttle to reduce drive train oscillations during the process of engaging the clutch;
- observing clutch engagement;
- and
- returning engine throttle control to the vehicle driver in response to observing that said clutch is engaged.
Dependencies are inferred from the claim text.