Abstract:
Systems and methods for improving operation of a hybrid vehicle are presented. In one example, application of a driveline disconnect clutch to start an engine is described. The approach applies the driveline disconnect clutch to rotate an engine and at least partially disengages the driveline disconnect clutch to reduce the possibility of a reduction in torque applied to vehicle wheels.
Abstract:
A hybrid vehicle has an engine, an electric machine connected to the engine by an upstream clutch, a transmission gearbox connected to the electric machine by a downstream clutch, and a controller. The controller is configured to, in response to a user commanded shift of the transmission, control the electric machine speed to a designated speed based on gearbox output speed and the transmission gear ratio after the shift, thereby synchronizing speeds across the gearbox for the shift. A method for controlling a hybrid vehicle provides, in response to a user commanded shift of an automatic transmission gearbox, controlling an electric machine speed to a target speed based on the transmission gear ratio after the shift where the target speed is synchronized with the transmission gearbox output speed.
Abstract:
Methods and systems are provided for reducing audible clunks and objectionable drive feel in vehicles including start/stop systems. In one example, a vehicle engine is shutdown during vehicle coasting. The vehicle engine is then restarted, while the vehicle is moving with a torque converter clutch disengaged. A transmission clutch pressure is then adjusted during the restart based on a torque converter output speed relative to a torque converter input speed.
Abstract:
A speed ratio shaft control for multiple ratio vehicle transmission has controlled release of an off-going transmission clutch and controlled engagement of an on-coming transmission clutch during a speed ratio upshift, at least one clutch being a friction torque establishing clutch. A controller, using shift-timing software strategy, actively manages in real time a clutch torque level for each clutch so that transient torque disturbances in a transmission torque output shaft are mitigated.
Abstract:
Systems and methods for operating a driveline of a hybrid vehicle are described. In one example, vehicle launch is controlled according to a linear quadratic regulator that provides feedback control according to torque converter slip error and vehicle speed error. The vehicle launch is also controlled according to feed forward control that is based on requested torque converter slip and requested vehicle speed.
Abstract:
Powertrains may include a spring damper between the engine crankshaft and transmission input shaft. In some circumstances, an oscillation known as shuffle may occur in such powertrains. Active adjustment of engine torque is substantially more effective at mitigating shuffle oscillations if the engine torque includes a p-term proportional to displacement of the damper spring in addition to a d-term proportional to the speed difference across the damper. For various reasons, the spring displacement is difficult to measure directly. An observer algorithm is utilized to calculate a current estimated spring displacement based on a crankshaft speed sensor, a transmission input speed sensor, a wheel speed sensor, and past engine torques, using a dynamic model of the powertrain.
Abstract:
Methods and systems for improving operation of a vehicle driveline that includes an engine and an automatic transmission with a torque converter are presented. In one non-limiting example, the engine may be stopped while a vehicle in which the engine operates is rolling. A transmission coupled to the engine may be shifted as the vehicle rolls so that vehicle response may be improved if a driver requests an increase of engine torque.
Abstract:
To reduce fuel consumption, a transmission is shifted into a neutral state, called neutral idle, when a vehicle stops in a drive mode. During a transition from a neutral idle state to an engaged state, the engine torque is controlled to avoid excessive shift energy and to mitigate acceleration drop. Specifically, the engine torque is set to a level equal to a sum of a transmission torque capacity and an offset, which is a function of accelerator pedal position. The transmission torque capacity is calculated based on the engaging shift element torque capacity and torque ratios associated with the kinematics and the torque converter. To accommodate noise factors such as variation over time, the offset function is adapted in response to measured clutch energy and acceleration drop.
Abstract:
Systems and methods for improving operation of a driveline disconnect clutch for a hybrid vehicle shifting are presented. In one example, pressure of a working fluid supplied to the driveline disconnect clutch is adjusted in response to a rate of change in accelerator pedal position. Further, pressure of the working fluid may be decreased responsive to selected operating conditions.
Abstract:
Systems and methods for operating a transmission of a hybrid vehicle's driveline are presented. In one example, the systems and methods adjust operation of an electrically driven transmission pump that supplies transmission fluid to one or more transmission components in response to a rotational stopping position of a mechanically drive transmission pump.