Jatco Corporation

Nissan Motor Company Limited

Jatco Transtechnology Ltd.

Jacto Ltd

Kazuhiro Takatori

Osamu Sato

Tatsuya Imamura

Yasushi Fujita

Kazuhito Sano

Kazuo Tomioka

Toshihide Fukasawa

Hiroyuki Hirano

Kenji Ikeura

Nobuteru Hitomi

Kunihiko Morikawa

Masaki Sugimoto

Hisashi Kitahara

Tatsuo Wakahara

Hiromasa Sakai

Morimasa Yamawaki

Satoshi Sakakibara

Chiaki Harada

Koji Koizumi

Nobuaki Mochizuki

Hiroyuki Tsukamoto

A shift pressure control apparatus for an automatic transmission is arranged to hold the shift pressure during a shift at a starting input-torque-dependent pressure determined from a transmission input torque at a start of a shift. A controller is configured to monitor an operating parameter representing an engine load of an engine, to detect an engine load change. When the engine load change is detected, the controller modifies the shift pressure to a modified pressure determined by modifying the starting input-torque-dependent pressure with a difference between a second engine-load-dependent pressure determined from the engine load after the engine load change and a first engine-load-dependent pressure determined from the engine load at the start of the shift.

Shift pressure control for automatic transmission

A lock-up control device for a lock-up torque converter of an automatic transmission is provided which starts measuring an elapsed time when the throttle opening exceeds a first predetermined value due to depression of an accelerator pedal during lock-up clutch slip control. When the throttle opening exceeds a second predetermined value due to sudden depression of the accelerator pedal prior to the elapse of a determination time, a transmission controller terminates the lock-up clutch slip control. After a rapid increase, the slip amount starts decreasing upon termination of the lock-up clutch slip control. Therefore, the temperature of a facing stops rising when the lock-up clutch slip control is terminated, and this improves the durability of the facing. The lock-up clutch slip control is re-started when the throttle opening is reduced to a predetermined value, and this maintains the excellent fuel economy performance.

Lock-up control device for torque converter of automatic transmission

A pressure regulating valve regulates an original pressure outputted from a manual valve by means of a control pressure generated by a solenoid in a D range and supplies the regulated original pressure to an engaging element. An electronic control unit filters a current signal supplied to the solenoid to generate the control pressure by using a strong filter when a N range is switched to a D range during stoppage of a vehicle so that the control pressure has a gentle rise characteristic, switches the filtering process to a filtering process using a weak filter to rapidly move the pressure regulating valve in a working pressure discharge direction when the N range is switched to the D range during running of the vehicle and returns the filtering process to the filtering process using a strong filter after a predetermined time period. Thereby, occurrence of shock is suppressed when the D range is again selected after the N range is selected during running in the D range.

Control system for automatic transmission

A shift control system for an automatic transmission having an automatic shift mode in which a proper gear ratio is automatically selected according to a shift command based on a throttle valve opening and a vehicle speed, and further having a manual shift mode in which a gear ratio is selected according to a shift command given by driver's manual operation. The shift control system includes timer means for counting an elapsed time after a shift operation has been started. The elapsed time is compared with a predetermined first re-shift permission time in the case of automatic shift operation and with a predetermined second re-shift permission time in the case of manual shift operation. The first re-shift permission time and the second re-shift permission time are different from each other to optimize the shift control both in the automatic shift mode and in the manual shift mode.

Shift control system for automatic transmission

An automatic transmission has a gear transmission mechanism with engaging devices. Up-shifting is achieved with oil pressure, which is controlled with an open control component, a gradient of which is determined based on input torque, and a feedback control component, which is based on a target gear ratio. To prevent shock during an up-shift caused by releasing the accelerator, the feedback control component is set to zero when the amount of change in the throttle opening is equal to or greater than a predetermined threshold value. As a result of inhibiting increase in feedback to make up for a tendency for oil pressure depending on an open control component to decrease as a result of the throttle opening reducing and input torque falling, increase of the oil pressure command value becomes smooth. Peaks of the output torque are therefore suppressed.

A hydraulic control system controls a hydraulic pressure as a standby pressure in a period from an engagement start point at which an engagement instruction for engaging a friction element is started to an abutment start point at which an abutment between an input element and an output element is started. The hydraulic pressure supplied to at least one friction element is so increased as to switch the friction element from a disengagement state to an engagement state, thus transmitting a revolution of the input element of the friction element to the output element of the friction element. The hydraulic control system includes: a speed sensor for sensing a speed of the friction element; and a standby pressure increase section for increasing the standby pressure in accordance with the speed of the friction element sensed with the speed sensor.

Hydraulic control system for automatic transmission, and method of controlling hydraulic pressure

When a transmission selector lever is operated from P or N range to D range, an input clutch to be engaged at the fifth gear position is temporally engaged to reduce shift shock when the engaging element for the first gear position is engaged. An oil pressure command value for actuating the input clutch is increased with a constant inclination from a start point oil pressure value, and the start point oil pressure value is lowered when the engine speed is low or when an oil temperature is high. Even if a timing of completion of filling of working fluid to the input clutch is fluctuated, the difference between the actual oil pressure and the oil pressure command value is suppressed to a small level and the occurrence of shock due to surge at the time of the filling completion is prevented.

An initial command oil pressure of a lock-up control of coasting lock-up region is set by using a lock-up learning correction amount calculated by a learning control in a lockup control of the other of the plurality of lock-up regions such as slip lock-up region and complete lock-up region when one of the lock-up control of these other lock-up regions is performed before the lock-up control of the coasting lock-up region. Thus, a lock-up learning correction amount can be commonly used among three kinds of lock-up regions, and a lock-up as set is early realized in each lock-up region.

In solenoid control method and apparatus for an automatic transmission, a current signal varied in a stepwise manner is caused to pass through a filter having a predetermined transfer function, the current signal being inputted to a solenoid to drive a control valve by which a working oil pressure on at least one frictional element of the automatic transmission is controlled by reducing the working oil pressure to release the frictional element and the filter passed current signal is inputted to the solenoid to drive the control valve. The solenoid control method and apparatus described above are applicable to a change-over shift operation.

Solenoid control method and apparatus for automatic transmission

A control system for controlling operation of a pre-charge system of an automatic transmission. The control system comprises a first section which receives first and second gear change instructions which are issued in succession. The first and second gear change instructions are of a type of needing an engaged condition of a same friction element. The control system further comprises a second section which, when the second gear change instruction is issued during a pre-charge period of the friction element which is needed by the first gear change instruction, extends the pre-charge period of the friction element to a time when a pre-charge period needed by the second gear change instruction lapses.

Pre-charge control system of automatic transmission

A standby phase target time is determined with reference to a table according to a read engine load and vehicle speed. A standby phase real time is then measured, and a learning correction value is calculated and stored. In a next shifting operation, a value that is found by adding the learning correction value to a hydraulic pressure command value in the previous shifting operation is used as a new hydraulic pressure command value. This learning correction is performed in small regions where the vehicle speed increases with the throttle opening being substantially constant. This accurately compensates a change in characteristics of a hydraulic system without being affected by a rapid change in torque or the like.

Shift control system of automatic transmission

In an automatic transmission performing change-over of a first engaging element and a second engaging element between two gear positions, for example between the fourth gear and the fifth gear, an oil pressure command value A to one of these two engaging elements is retained as a current value &ldquo;a&rdquo; and an oil pressure command value B to the other of these two engaging elements is retained as a current value &ldquo;b&rdquo; and at the same time the calculation of a calculation value of a downshift form the fifth gear is started when a target gear position changes to the fourth gear or lower during upshift between the two gear positions. When downshift calculation values Ad, Bd reach the retained values &ldquo;a&rdquo;, &ldquo;b&rdquo;, the oil pressure command values A, B are switched to the downshift calculation values. Thereby, a timing for performing the change-over of respective engaging elements is properly achieved, and a downshift to the fourth gear can be promptly performed before the upshift is not finished, and shift shock and engine racing can be prevented.

A motor vehicle includes an internal combustion engine and an automatic transmission powered by the engine. The engine has a throttle valve for controlling the amount of air fed thereto. The transmission selectively assumes an Over-drive possible D-range wherein both a lock-up ON condition and a lock-up OFF condition are available and an Over-drive impossible D-range wherein only the lock-up OFF condition is kept. A control system comprises a first section for detecting a first condition of the engine wherein an open degree of the throttle valve is reduced to a certain degree; a second section for detecting a second condition of the transmission wherein the lock-up ON condition of the Over-drive possible D-range is kept; and a third section for engaging a friction element of the transmission to induce an engine brake when the first and second sections detect the first and second conditions respectively.

Control system of automotive automatic transmission

A line pressure control apparatus of an automatic transmission controls the line pressure of the automatic transmission under a lockup condition to ensure an engagement capacity and an amount of lubrication oil for an engaged friction element under a high vehicle speed condition. The line pressure control apparatus comprises a line pressure lowering section, a vehicle speed deciding section and a pressure changing section. The pressure lowering section lowers a line pressure under a lockup condition of the automatic transmission. The vehicle speed deciding section decides whether a vehicle speed of the automotive vehicle is higher than a predetermined value. The pressure changing section changes the line pressure under the lockup condition from the lowered line pressure to a line pressure under a normal condition when the vehicle speed is higher than the predetermined value.

Line pressure control apparatus of automatic transmission

An automatic transmission has a friction element which induces a certain speed gear of the transmission when hydraulically operated. A fluid control circuit of the transmission comprises an accumulator valve unit which receives a line pressure for regulating a pressure of an operation fluid applied to the friction element in accordance with an engine load; and a shift valve which feeds the line pressure to the accumulator valve unit when assuming a first position and drains the operation fluid when assuming a second position. A flow restriction device is employed in the fluid control circuit for restricting the draining flow of the operation fluid.

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Fuji, Japan

Kazuhiro Takatori