摘要:
When it is determined to perform nth to (n+1)th coast downshift during nth to (n+1)th power-off upshift, an ECU starts increasing control to increase the hydraulic pressure of an engage-side element A in a predetermined mode and maintains the hydraulic pressure of a release-side element B at a value at which the increasing control is started until a predetermined period of time elapses from when the start of the increasing control. When a turbine rotational speed does not increase even after the predetermined period of time has elapsed, as the turbine rotational speed decreases below a value lower by a predetermined value than a synchronous rotational speed in the (n+1)th gear, the ECU executes feedback control over the hydraulic pressure of the element B so that the turbine rotational speed becomes the value lower by the predetermined value than the synchronous rotational speed in the (n+1)th gear.
摘要:
The invention relates to a vehicle integrated-control apparatus and method that sets a final control target by coordinating a control target primarily set based on an input of a driver with instruction values from the control systems; and that causes a drive control system to control a drive source and a stepped automatic transmission to achieve the final control target. With this apparatus and method, at least one of the control systems, which provide instruction values to be coordinated with the primarily set control target, is notified of a range of control targets that can be achieved at a current shift speed; a range of control targets that can be achieved by changing the current shift speed to a currently achievable shift speed; and a range of control targets that can be achieved without changing the current shift speed to another shift speed.
摘要:
In shift control apparatus and method for an automatic transmission in which an engine speed is inputted, and a shift change in a shift stage of the automatic transmission is performed to make a gear shift, a shift revolution synchronization control in synchronization with the engine speed is performed and, in a case where the gear shift is made under a driving state in which there is a possibility of an occurrence of a shift shock, an engagement section which performs a power transmission under a presently selected shift stage is gradually released and another engagement section which enables a power transmission through the next selection scheduled shift stage is gradually engaged without an execution of the shift revolution synchronization control.
摘要:
A shift control apparatus for a vehicular automatic transmission provided with a fuel cut apparatus which cuts off fuel supplied to an engine when an engine speed exceeds a predetermined value during deceleration of a vehicle, and an automatic transmission in which a gearshift is achieved with a clutch-to-clutch downshift in which a hydraulic friction device to be released is released and a hydraulic friction device to be applied is applied, further includes a controller. The controller corrects, through learning control, an apply pressure of at least one of the hydraulic friction devices to be operated for the clutch-to-clutch downshift such that an amount of drop in a rotational speed of an input shaft of the automatic transmission increases when that amount of drop is less than a predetermined value during the clutch-to-clutch downshift.
摘要:
A control strategy for a multiple-ratio transmission for an automotive vehicle comprising a shift valve system that responds to shift valve signals developed by a microprocessor controller, the controller being in communication with engine sensors indicating engine operating variables and transmission sensors indicating transmission operating variables, the shift valve system responding to shift signals developed by the microprocessor during coasting downshift of the vehicle from one gear ratio to a lower gear ratio with a closed engine throttle whereby torque reversals are avoided during coast-down, thereby eliminating inertia torque changes to improve the smoothness of coasting downshifts during cold engine operation.
摘要:
A vehicle automatic transmission control controls fluid pressure changes applied to a frictional engagement element which is being changed from an engaged state to a disengaged state at a stage before input shaft rotational speed starts to increase from the beginning of a down-shift control. The control instruction value is set to gradually decrease the applied fluid pressure and to increase the ratio of such decrease with elapsed time. Specifically, a solenoid is used to control the fluid pressure applied to a clutch. The duty-cycle instruction for the solenoid is determined based on a quadratic function expressed as: duty cycle value=initial value-at.sup.2.
摘要:
A shift control apparatus in a vehicle automatic transmission, where down-shift is carried out from a high velocity step to a low- velocity step.A flatness-aiming control has a common targetted change rate with respect to a turbine rotational speed in the inertia phase, and aims a hydraulic command value for the engaging side element and a hydraulic command value for the releasing side element at flatness in the inertia phase with the passage of time.An initial value setting control sets an engaging side initial value and a releasing side initial value at the beginning of the inertia phase in response to the turbine torque and the turbine rotational speed.
摘要:
An interactive cruise control system and method for providing automatic speed control of a vehicle with improved shifting of an automatic transmission. The system and method controls speed of a vehicle equipped with cruise control and minimizes downshifts in an automatic transmission of the vehicle. Vehicle speed is detected and compared with a setpoint speed which is associated with the cruise control system. Transmission gear shifting is determined based on predetermined shift schedule points. Determined transmission gear downshifts are prevented for a kickdown delay period based on vehicle speed loss and the presence of vehicle deceleration. Also provided is an overspeed reduction method for causing a transmission downshift during an overspeed condition with the throttle closed. Further, the system provides hunting prevention between both second gear and third gear as well as between third gear and fourth gear for a four speed automatic transmission.
摘要:
In a shift control method, when a speed ratio of an automatic transmission is shifted from a third speed ratio to a first speed ratio before stoppage of a vehicle, a down shift line 3-1 in a shift pattern is shifted to a high-speed side to initiate shifting under a power-OFF condition. A third brake is released by setting the duty ratio of an electromagnetic valve of the third brake at 0% to establish a free condition (neutral condition) in an output shaft of a second transmission. While the duty ratio of an electromagnetic valve of a second clutch in a first transmission mechanism is set at 0%, the duty ratio of an electromagnetic valve of a second brake is gradually increased, so that the shifting from the second clutch to the second brake is made, and the first transmission mechanism is operatively shifted from the third speed ratio to a speed ratio corresponding to the first speed ratio. Then, the third brake is engaged again upon completion of the shifting and after mechanical engagement of a one-way clutch. Consequently, it is possible to reduce shocks in shifting the speed of the vehicle.
摘要:
A shift control system for an automatic power transmission is capable of optimizing operation timing of a timing valve and whereby eliminate a shift-shock and occurrence of racing. The system includes an input device including a detector for detecting a vehicle speed and a load detector for detecting an engine load, a switching device for switching states of the friction elements for establishing the transmission speed ratios, a switching controller for selecting a transmission speed ratio among the speed ratios on the basis of the inputs from the input device and issuing a shifting demand for the switching device, a measuring device for measuring an elapsed time from a timing of recognition of the shifting demand from the switching controller, a timing adjusting device for adjusting response of hydraulic pressure supply for the friction elements upon down-shifting, a weighting and summing derive for deriving weighted sum of inputs including at least the vehicle speed, the elapsed time from the timing of recognition of the shifting demand and the engine load, upon down-shifting, and a timing control device for outputting a control signal to operate the timing adjusting devicee to perform a predetermined operation when the weighted sum derived by the weighting and summing device exceeds a predetermined threshold value.