Jatco Transtechnology Ltd.

Jatco Corporation

Yuji Saito

An automatic transmission is driven by an engine through a torque converter. The transmission includes a plurality of friction elements which are selectively engaged to provide a selected gear thereby to transmit the power of engine to an output shaft of the transmission while changing the rotation speed. A speed change completion degree estimating system is provided, which comprises a first section that derives a difference (Nt&minus;Ne) between an input rotation speed (Nt) of the transmission and an engine rotation speed (Ne); a second section that derives a difference (g&times;No&minus;Ne) between the input rotation speed (g&times;No) of the transmission provided after completion of the speed change operation and the engine rotation speed (Ne); and a third section that calculates a speed change completion degree (Shift) of the transmission by using a ratio between the (Nt&minus;Ne) and the (g&times;No&minus;Ne).

Speed change completion degree estimating system of automatic transmission and speed change control device using same

When a reshift request for a second shift to a second gear ratio is produced during a first shift operation to a first gear ratio in an automatic transmission, a reshift control apparatus performs a reshift operation in response to the reshift request in a first reshift control mode by terminating the first shift operation at an intermediate state without completing the first shift operation, and instead initiating the second shift operation from an intermediate state.

Reshift control system for automatic transmission

In gear shift controlling method and apparatus for an automatic transmission, the automatic transmission comprising a plurality of frictional elements, a working liquid pressure for each of first and second frictional elements is controlled to make a gear shift in the automatic transmission in such a manner that while the first frictional element is released by a decrease pressure control for the working liquid pressure, the second frictional element is clutched by an increase pressure control for the working liquid pressure and a release capacity during an inertia phase during which the gear shift from a first gear range to a second gear range occurs is set in accordance with an instantaneous gear ratio during the inertia phase so as to output the release capacity set according to the instantaneous gear ratio.

Apparatus and method for controlling gear shift for automatic transmission

In a shift control device for an automatic transmission capable of switching from a normal automatic shift control to a drive-downshift forcible termination control when a time rate of change in transmission input speed is reduced to below a threshold value owing to a drop in transmission input torque during drive downshift from a higher gear position to a lower gear position with an accelerator pedal depressed, a drive-downshift forcible termination control section is provided. The drive-downshift forcible termination section executes the drive-downshift forcible termination control only when the time rate of change in transmission input speed is reduced to below a first predetermined threshold value and a value equivalent to the transmission input torque is reduced to below a second predetermined threshold value, to forcibly terminate the drive downshift.

Shift control device for automatic transmission

If, in a gear shift from one-way clutch involved gear speed to another gear speed, the inertia phase control time) is less than a predetermined time length, or the effective gear ratio on the inertia phase end detection instant is out of a range between before-shift gear ratio and after-shift gear ratio, a transmission control system controls the operating fluid pressure in a time management mode to prevent a shift shock by increasing the fluid pressure) at a gradual rate &Dgr;PC during a longer time interval TMC after an end of the inertia phase.

Shift control apparatus for automatic transmission

An automatic transmission controller carries out (a) changing a control for engaging the engaging-side frictional element between in a first condition in which a speed of progression in the shift is managed mainly in accordance with a volume of the hydraulic fluid to be supplied to the engaging-side frictional element itself and in a second condition in which the shift progresses regardless of the volume of hydraulic fluid to be applied to the engaging-side frictional element itself; and (b) accomplishing a volume control for the engaging-side frictional element from a timing immediately after a decision of the shift under a command hydraulic pressure of the hydraulic fluid to be supplied to the engaging-side frictional element in the second condition, the command hydraulic pressure having a lower limit value for securing that a piston stroke of the engaging-side frictional element completes within a predetermined time.

Shift control system for automatic transmission

An automatic transmission includes a low reverse brake and a reverse clutch that are engaged at different timings to determine a selected gear position, the reverse clutch being engaged immediately before the low reverse brake to be engaged last. It is determined whether or not a piston for actuating the reverse clutch has completed its stroke up to the position where it can start actual engagement. Before determination that the piston of the reverse clutch has completed its stroke up to the position where it can start actual engagement, it is prevented to determine whether or not a piston for actuating the low reverse brake has completed its stroke up to the position where it can start actual engagement.

System and method of determining completion of piston stroke in automatic transmission

In an automatic transmission, transient control of the working oil pressures for friction elements whose state is to be switched is normally carried out in accordance with a degree of shift development determined based on at least a vehicle speed. When the vehicle speed is too low to provide determination of the degree of shift development, transient control of the working oil pressures for the friction elements is carried out in accordance with elapsed time from shift instead of normal transient control.

Shift control system and method for automatic transmissions

In a replacement gear shift effected by engagement of a first friction engagement element by increasing a first fluid pressure and instead by disengagement of a second friction engagement element by decreasing a second fluid pressure, a shift control apparatus forcibly increases the first fluid pressure at a gradual rate to prevent an undesired shift shock if the inertia phase does not end within a predetermined time.

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Shizuoka, Japan

Yuji Saito