摘要:
An improved shift control for a hydraulic automatic transmission in which the apply chamber of an on-coming clutch is filled in the preparation phase of the shift using a hydraulic flow rate model to estimate the volume of hydraulic fluid supplied to the apply chamber. In an initial portion of the fill interval, fluid is supplied to the apply chamber at a first elevated pressure, while continuously updating the fluid volume estimate. When the remaining un-filled volume of the apply chamber reaches a reference volume, the supply pressure is reduced to a second pressure at which the next phase of the shift is to be carried out. When the chamber volume is filled, the torque capacity of the clutch rises to a level corresponding to the second pressure, and the next phase of the shift automatically ensues.
摘要:
An improved control for an automatic transmission garage shift, wherein a dynamic model of the transmission is used to estimate the transmission input torque during the shift and to schedule the on-coming clutch pressure in accordance with the estimated input torque to achieve a desired input shaft trajectory. The transmission input torque is estimated based on two different methodologies —one suited to steady-state engine idle conditions, and the other suited to engine output torque transient conditions. A fuzzy summation of the input torques provided by the two methodologies is utilized in transitions between the two conditions. Shift quality variations due to variations in mechanical and/or hydraulic stiffness are minimized by a pause or hold interval inserted between the end of the fill period and the initiation of on-coming clutch pressure control, which results in a reasonably consistent degree of perceived transmission-to-transmission hydraulic and mechanical compliance.
摘要:
An improved control for an automatic transmission upshift, wherein the engine output torque and on-coming clutch pressure are coordinated during the shift based on an inverse dynamic model of the transmission to achieve a desired output torque trajectory. The desired output torque trajectory is influenced by operator demand, and an initial value of the desired output torque trajectory is used along with the engine output torque to develop an input acceleration trajectory. The inverse dynamic model of the transmission is used (1) to determine an engine torque command that will achieve both the input acceleration trajectory and the desired output torque trajectory, and (2) to determine a feed-forward pressure command for the on-coming clutch that will produce the input acceleration trajectory, given the engine torque command. The desired output torque trajectory and the engine output torque are used to determine the expected input speed, and a feed-back control term based on the deviation of the measured input speed from the expected input speed is used to adjust the on-coming clutch pressure command to account for model errors. Finally, the closed-loop feedback error is used to enable adaptive correction of the feed-forward control so that the feed-forward clutch pressure more nearly produces the commanded input shaft acceleration.
摘要:
An improved control for an automatic transmission closed-throttle downshift, wherein closed-throttle engine torque is used to raise the transmission input speed to the synchronous speed of the target speed ratio, and wherein the on-coming clutch is controlled in a manner to complete the shift with minimum driveline torque disturbance in spite of clutch control variability. The invention includes a primary on-coming clutch control for completing the downshift when the input speed reaches the synchronous speed, and a contingent on-coming clutch control that is initiated if shift completion is not achieved by the primary control, the contingent control being effective to re-establish input speed synchronization and thereupon engage the on-coming clutch to complete the shift. The primary clutch control involves holding the on-coming clutch in readiness for engagement while the input speed approaches the synchronous speed, and when the synchronous speed is reached, raising the on-coming pressure by a predetermined amount designed to maintain the input speed at the synchronous speed. The contingent clutch control includes a first open loop stage that progressively increases the on-coming clutch pressure to gradually re-establishing the input speed synchronization, and a second closed-loop stage that adjusts on-coming clutch pressure to conform the input speed to a defined trajectory.
摘要:
An improved on-coming clutch fill control method in which a model of the transmission hydraulic system is used for control purposes to accurately predict the achievement of on-coming clutch torque capacity based on a comparison of the modeled volume of supplied fluid to a reference volume representing the actual volume of the on-coming clutch, and in which the reference volume for each type of shift is adaptively adjusted based on input speed aberrations observed during shifting. If input speed flaring occurs due to an underestimated reference volume, the reference volume is adaptively increased based on the volume of fluid supplied to the on-coming clutch between the initial detection of flaring and a detection of maximum flaring. If the input speed does not flare, but an early pull-down or overlap is detected, the reference volume is adaptively decreased based on the volume of fluid supplied to the on-coming clutch between the initial detection of pull-down or overlap and the expected achievement of on-coming clutch torque capacity.
摘要:
An improved speed indication method for a sensor that develops one or more electrical pulses per unit movement of a movable part, wherein the indicated speed is based on the number of speed pulses generated per unit time, but is constrained by a limit function based on the time elapsed without the generation of a speed pulse. When the pulse generation rate falls below the update rate of the speed indication, a maximum possible speed based on the duration of the “no pulse interval” is computed, and the indicated speed is reduced based on the computed maximum. When the next pulse occurs, the speed indication is updated based on the lower of a new speed calculation and the computed maximum speed. If speed pulses continue to be received, the computed maximum is no longer used as a limit, and the speed indication is updated in accordance with the pulse based speed calculation. As a result, the indicated speed provides a smoothly varying and more accurate representation of the shaft speed at very low speeds, enabling more accurate low speed control.
摘要:
An improved control for an automatic transmission power-on downshift, wherein a dynamic model of the transmission is used to schedule the on-coming and off-going clutch pressures based on the transmission input torque and a desired trajectory of the input shaft during the shift. The shift is initiated with the off-going clutch by using the dynamic model achieve consistent initiation of clutch slippage, and to conform the input speed to the desired trajectory. When the input speed nears a synchronization speed for the target speed ratio, the dynamic model is used to engage the on-coming clutch at a rate based on the input torque while maintaining the input speed in synchronism with the target speed ratio. As a result, the control responds appropriately to dynamic changes in input torque, the input speed more accurately tracks the desired trajectory, and the shifts are completed at or near synchronism. Additionally, scheduling the clutch pressures based on the dynamic model achieves more consistent shift feel and improved adaptability to different powertrain and vehicle-type configurations while reducing the number of calibrated parameters requiring adaptive correction.
摘要:
An improved control for an automatic transmission upshift, wherein the on-coming clutch pressure (Ponc) is scheduled during the torque and inertia phases of the shift in accordance with the summation of feed-forward and feed-back control terms, the feed-forward control term being developed using an inverse dynamic model of the transmission. The feed-forward control term is determined by developing a desired acceleration trajectory of the input shaft, and periodically applying the acceleration trajectory to the inverse dynamic model to obtain an estimate of the required on-coming clutch pressure, given the transmission input torque. The feed-back control term is based on a comparison of the expected input speed response with the actual input speed response, and corrects for modeling errors in the feed-forward control, providing disturbance rejection and improved command following. Additionally, the closed-loop feedback error is used to enable adaptive correction of the feed-forward control so that the estimated on-coming clutch pressure more nearly produces the commanded input shaft acceleration. Controlling the input shaft acceleration in this manner achieves more consistent shift feel and energy dissipation in the on-coming clutch, with less intensive calibration effort and improved adaptability to different powertrain and vehicle-type configurations.
摘要:
An improved force motor current control including feed-forward and feed-back control terms summed to determine a force motor activation for achieving a current command. The feed-forward control term estimates the force motor activation required to achieve the current command, based on the force motor temperature, the system voltage and a model of the force motor circuit. The feed-back control term compares an expected response to the actual response and develops a control term that corrects for modeling errors, providing disturbance rejection and improved command following. The closed-loop feedback error is used to enable adaptive correction of the feed-forward control so that the estimated force motor activation more nearly produces the commanded current.
摘要:
An improved engine and transmission control method for coordinated control of closed-throttle transmission shifting, wherein the transmission control provides engine speed and torque rate limits to the engine control based on the shift parameters. The speed and/or torque rate limits come into play if the driver suddenly increases the engine throttle setting. Additionally, in driver requested garage shifts, initiation of the shift is prevented until the engine speed is within the speed limit. Preferably, the engine speed limit is set a calibrated amount above the computed input synchronization speed (SYNC). Alternately, the engine speed limit may be set to a value that limits the energy dissipated in the on-coming clutch to a predetermined value. With either approach, the engine speed and torque limits modify the engine control only to the extent necessary to preserve high shift quality while limiting the on-coming clutch energy dissipation to a safe level.