Mazda Motor Corporation

Mazada Motor Corporation

Fumiaki Baba

Hiroshi Yoshimura

Takuji Fujiwara

Masahito Kitada

Tatsutoshi Mizobe

Kazuo Takemoto

Koichiro Takeuchi

Shinya Kamada

Koichi Yamamoto

Kozo Ishii

Keiji Bota

Kenji Sawa

Shigeru Nagayama

Osamu Watanabe

Masanori Izumi

Susumu Kurumida

Jyujiro Oda

A control system for a torque converter includes a lock-up clutch provided in the torque converter for connecting input and output members of the torque converter directly, and a shift valve having first and second spools disposed in series in a sleeve for shifting an introduction of an engaging and releasing pressure acting on the lock-up clutch in accordance with positions of the first and second spools. The first spool is subjected to a first hydraulic pressure at one end thereof. The second spool is subjected to a second hydraulic pressure at one end thereof opposite to the one end of the first spool. The first and second spools are subjected to a third hydraulic pressure therebetween. The control system further has a first control device for controlling the first hydraulic pressure, and an adjusting valve for controlling the releasing pressure of the lock-up clutch. The shift valve provides the first and second spools with first, second and third positions corresponding to a converter condition, lock-up condition and slip condition, respectively. The shift valve is shifted between the second and third positions when the releasing pressure is relatively low so that the releasing pressure is continuously changed irrespective of the shifting action among the first, second and third positions of the shift valve. An abrupt change in the engaging force of the lock-up clutch is prevented.

Control system for torque converter

A shift control system for an automatic transmission includes a shift gear mechanism for providing a plurality of shift stages of different speed ratios, a plurality of frictional elements, a first valve for controlling a hydraulic fluid supply, a second valve provided in a hydraulic release line to control hydraulic fluid release, a first frictional element included in the plurality of the frictional elements, a second frictional element included in the plurality of the frictional elements, a piston provided in the second frictional element, a timing valve for controlling a supply timing of the hydraulic pressure for the releasing chamber of the second frictional element in response to actuating hydraulic pressure introduced into the first frictional element, an oil temperature detecting device, and a start detecting device for detecting start of engaging operation of the first frictional element. A shift judging device for judging whether or not a shift command in the control unit is made to a specific shift stage in which the first frictional element is engaged and the second frictional element, is released. A shift control mode switching device switches between a first shift control mode and a second shift control mode, the shift control mode switching device selecting the first shift control mode when the temperature of the hydraulic fluid is relatively high, and selecting the second shift control mode when the temperature of the hydraulic fluid is relatively low. Torque shock and engine speed racing can be avoided through the shift operation.

Control system for automatic transmission

A control system for an automatic transmission includes a main hydraulic line to which hydraulic pressure is introduced when a manual valve takes a reverse range position for reverse movement. First and second hydraulic lines are separated from the main hydraulic line, a first frictional element is connected with the first hydraulic line, and a second frictional element is connected with the second hydraulic line. An accumulator is disposed on the second hydraulic line, a shift valve is disposed on the second hydraulic line closer to the second frictional element than the accumulator, and a first drain port is formed on the manual valve for draining hydraulic fluid from the main hydraulic line when the manual valve is shifted from the reverse range to another range. A spool is disposed in the shift valve for moving to a position to shift the shift valve so that the second line is interrupted by the shift valve and divided between a second frictional element line and an accumulator line. A second drain port is formed in the shift valve for draining the hydraulic fluid in the second frictional element line when the spool moves to the position where the shift valve interrupts the second hydraulic line between the second frictional element line and the accumulator line. A shift shock can be suppressed in a shifting operation involving the reverse range.

A control system for an automatic transmission has a shift gear mechanism with a plurality of frictional elements, including a low reverse brake which is selectively actuated for switching a power transmitting path to establish a desired shift stage. A hydraulic control circuit controls supply of a hydraulic fluid to and relief of the fluid from an actuator for the frictional element. An accumulator is provided in a hydraulic passage communicated with the low reverse brake for obviating a shock as the low reverse brake is engaged. Back pressure of the accumulator is controlled when a first shift gear stage is established through the engagement of the low reverse brake. A torque shock can be suppressed when the first stage is established in an L-range.

Control system for an automatic transmission

A shift control system for an automatic transmission including a shift gear mechanism for providing a plurality of shift stages of different speed ratios, a plurality of frictional elements to be selectively actuated for switching a power transmitting path to establish a desired shift stage, range selecting device for selecting a shift range at least between a forward and a reverse ranges through a manual operation of a driver, control device for providing the shift gear mechanism with a specific shift stage in which an input member and output member of the shift gear mechanism are rotated together with each other in the case where the reverse range is selected during a forward movement and thereafter a forward range is selected again, the specific shift stage being provided for a predetermined time period after the forward range is selected again. A double lock condition of the shift gear mechanism can be avoided.

Shift control system for an automatic transmission

A control system for a vehicle engine coupled with an automatic transmission, which comprises a detecting portion for detecting a condition of speed change operation in the automatic transmission, a speed sensor for detecting engine speed or turbine speed in the automatic transmission, a first period determining portion for determing a first period of time, in which the speed change operation is to be carried out, by calculation based on the speed detected by the speed sensor, a second period determining portion for determining a second period of time, in which the speed change operation is to be carried out, in accordance with a predetermined lapse of time after the condition of the speed change operation is selected, and a torque control portion operative to vary torque produced by the vehicle engine to suppress torque shock resulting from the speed change operation during the first period of time when a condition of shifting-up operation is detected by the detecting portion and to vary the torque so as to suppress torque shock resulting from the speed change operation during the second period of time when a condition of predetermined shifting-down operation is detected by the detecting portion.

Control systems for vehicle engines coupled with automatic transmissions

A line pressure control system for an automatic transmission, including a multiple shift stage transmission gear mechanism having a plurality of power transmitting paths of different speed ratios, has a line pressure control device for controlling a line pressure for frictional elements of the transmission gear mechanism associated with each other to establish a desirable shift gear stage. A shift period detector detects a time period for a shift operation, accomplished in terms of operation of the frictional elements controlled by the line pressure. A first compensating device controls the line pressure in terms of a learing control in a manner such that the time period for the shift operation is controlled to a target value. An abnormality detecting device detects an abrupt change, such as a turbine speed rise or, depression, or a driving torque depression in an operating condition of the transmission. A second compensating device compensates the line pressure prior to compensation of the line pressure by the first compensating device when the abrupt change is detected. The torque shock can be effectively obviated during a shift operation.

Line pressure control system for automatic transmission

A lock-up control system for an automatic transmission including a torque converter having an input member and an output member, a multiple stage gear transmission gear mechanism connected with the output member of the torque converter and having a plurality of gear stages and a lock-up clutch for connecting the input member and the output member bypassing the torque converter wherein an engaging force in the lock-up clutch is controllable so as to change the amount of torque transmitted through the lock-up clutch. The system comprises shift detecting device for detecting a shift operation in the transmission mechanism and control device for controlling the engaging force of the torque converter to be maintained at a predetermined value smaller than a fully engaged condition of the lock-up clutch and larger than an entirely released condition of the lock-up clutch when the shift operation is detected by the shift detecting device.

Lock-up control system for automatic transmission

A shift control system for the vehicle contains a torqueconverter, a multiple stage gear mechanism adapted for a shift of an operating state of a friction coupling means of a hydraulic pressure type which is coupled to the torque converter, a temperature sensor for sensing temperatures of the operating oil for the torque converter and the friction coupling element, and a control unit for shift control. The control unit controls operation of the friction coupling elements on the basis of a predetermined shift characteristic and shifts the shift characteristic, when the temperature of the operating oil to be sensed by the temperature sensor is lower than a given value, is in such a manner that the area of driving at least for first speed stage is narrowed.

In an automatic transmission, a hydraulic pressure control valve produces hydraulic pressure according to a pilot pressure fed thereto. A duty solenoid valve controls the pilot pressure. An oil temperature sensor detects the temperature of the hydraulic oil and a driving period changing circuit changes the driving period of the duty solenoid valve according to the temperature of the hydraulic oil so that the driving period is long when the temperature of the hydraulic oil is low and short when the temperature of the hydraulic oil is high.

Duty solenoid valve control system for an automatic transmission

A control system for a vehicle engine coupled with an automatic transmission, which comprises a torque controller operative to vary torque produced by the vehicle engine, in accordance with a controlled variable, so as to suppress torque shock resulting from a speed change operation carried out to vary a gear ratio in a power transmitting gear arrangement provided in the automatic transmission, an operation detector for detecting the speed change operation, a controlled variable setting device for determining the controlled variable in accordance with an operating condition of the vehicle engine and the speed change operation, and a controlled variable revising device for varying the controlled variable so as to reduce variation in the torque brought about by the torque controller under a condition in which the speed change operation causing a change from one to another of speed ranges of relatively small gear ratios is detected by the operation detector, as compared with variation in the torque brought about by the torque controller under a condition in which the speed change operation causing a change from one to another of speed ranges of relatively large gear ratios is detected by the operation detector.

A control system for an automatic transmission employed in a vehicle comprises a torque converter coupled with an engine, power transmitting gear arrangement disposed at an output end of the torque converter, a speed change mechanism for giving rise to speed change in the power transmitting gear arrangement, a fluid servo control device having an applying chamber and a releasing chamber to each of which a fluid is supplied and operative to cause the speed change mechanism to work, and an additional control device for controlling the fluid servo control device under a situation in which the fluid in the releasing chamber of the fluid servo control device is so controlled as to have one of speeds in the power transmitting gear arrangement. The fluid servo control device is controlled by the additional control device to be in a first condition wherein the fluid is supplied to the applying chamber and in a second condition wherein the fluid is drained from the applying chamber selectively in response to the operating condition of the engine or the travelling condition of the vehicle.

System for controlling rate of speed change in automatic transmission

A control system for automatic transmission employed in vehicle comprises a torque converter coupled with an engine, a power transmitting gear arrangement coupled with the torque converter, a speed change device for giving rise to speed change in the power transmitting gear arrangement, a valve arrangement for controlling an operation fluid to be supplied to and drained from the speed change device, a revolving speed sensor for detecting the revolving speed of an input or output portion of the power transmitting gear arrangement when the shifting-down to a low speed with which an engine brake effect is to be obtained from a high speed in the power transmitting gear arrangement is carried out, and a control device for selecting, as the low speed of a target of the shifting-down, a first low speed with which the engine brake effect can be obtained and a second low speed with which the engine brake effect can not be obtained alternatively in response to the revolving speed detected by the revolving speed sensor. The control device selects further the first low speed after the second low speed is selected for a predetermined period of time on the occasion of the shifting-down.

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Higashihiroshima, Japan

Fumiaki Baba