Nissan Motor Company Limited

Jatco Corporation

Aichi Machine Industry Co., Ltd.

Hirofumi Okahara

Tatsuo Ochiai

Makoto Sawada

Koichi Hayasaki

Yasutaka Kawamura

Jihoon Kang

Hiroyasu Tanaka

Akito Suzuki

Nobuaki Mochizuki

Kazuhiko Sugano

Yutaka Suzuki

Yusuke Kimura

Shigeki Shimanaka

Tateki Jozaki

Hiromi Taguchi

Ikuo Hirose

Masahiko Yamada

Katsumi Doihara

Toshio Yamaguchi

Hironobu Waki

Yoshichika Hagiwara

Yoshimi Iwaya

Seiji Kaminaga

Donggyun Park

Wataru Onuki

Tsuyoshi Maeda

Yoshiyasu Murakami

Kiyoshi Kudou

An abnormal oil pressure reduction determining device has an oil pressure sensor which detects a real oil pressure, a sensor which detects a vehicle running state, and a controller which sets an oil pressure command value for an oil pressure control mechanism. The controller computes the lower limiting oil pressure which is possible in the present vehicle running state, and when the real oil pressure is less than this lower limiting oil pressure and the pressure difference between the real oil pressure and oil pressure command value exceeds a reference value, determines that there is an abnormal pressure reduction due to a fault in the oil pressure control mechanism. Even if the oil pressure of the transmission has dropped abnormally due to some reason, the abnormal oil pressure reduction determining device determines the situation without fail.

Abnormal oil pressure reduction determination device for vehicle transmission

A clutch engagement control device controls the engagement of a forward clutch () and reverse clutch () in an automatic transmission connected to an engine () in a vehicle. An inhibitor switch () outputs a range signal in accordance with a position range of a select lever (). A manual valve () supplies oil pressure selectively to one of the forward clutch () and the reverse clutch () by changing position in accordance with the position range of the select lever (). A controller () of the clutch engagement control device determines whether an unmatching range condition occurs in which the range of the select lever () indicated by the range signal and the range of the manual valve () do not match, when the range of the select lever () indicated by the range signal is a drive range or reverse range; and suppress an increase in engine rotation speed prior to engagement of the forward clutch or reverse clutch when the unmatching range condition occurs.

Clutch engagement control of automatic transmission

A vehicle engine () is connected with a belt-type continuously variable transmission () via a clutch (). The transmission () transmits torque via a belt () between a pair of pulleys (), and varies the transmission torque according to a supply of oil pressure. The clutch () engages by means of oil pressure supplied as a shift lever is changed over from a neutral range to a drive range. An oil pressure supplying device () supplies the oil pressure required to transmit torque between the belt () and the pulleys (), and the oil pressure for engaging the clutch (). Slippage between the belt () and the pulleys () is prevented during engagement of the clutch () by restricting the output torque of the engine () over a predetermined period of time.

Prevention of slippage in belt-type continuously variable transmission

A control system for an automatic transmission ( ) includes an oil pressure control mechanism ( ) for supplying an oil pressure to the transmission ( ), and sensor ( ) for detecting the oil pressure supplied from the oil pressure control mechanism ( ) to the transmission ( ). System controller ( ) calculates a maximum torque transmittable by the transmission ( ) based on a speed ratio of the transmission ( ) and the detected oil pressure; calculate an engine torque reduction amount from the difference between the torque being inputted into the transmission ( ) and the maximum transmittable torque; and reduce the torque of an engine ( ) according to the engine torque reduction amount.

Control system and control method for automatic transmission

In a vehicle transmission wherein plural speed change ratios from a largest speed change ratio to a smallest speed change ratio are selectively applied according to a command input by a driver, a real speed change ratio of the transmission is detected. It is determined whether or not the transmission is performing a shift-down based on the input command and the real speed change ratio. A shift-down limit speed change ratio is determined based on the speed change ratio before the shift-down operation is performed, and when the engine brake of the vehicle is operating, the transmission is controlled so as not to apply a speed change ratio larger than this shift-down limit speed change ratio. Due to this, the driver does not experience an excessive engine braking sensation even when an extreme speed change command is issued.

Speed change controller for automatic transmission

A speed change ratio of a stepless transmission of a vehicle is controlled so as to decrease the greater the vehicle speed, but this control of speed change ratio is suppressed when the drive wheels are slipping. This prevents misinterpretation of the slipping of the drive wheels as an increase of vehicle speed, and prevents shift-up of the transmission when the drive wheels are slipping.

Speed change ratio controller for stepless automatic transmission

A control system controls a line pressure applied to a CVT upon taking account of a certrifugal pressure caused by a rotation of pulleys. The control system determines whether the centrifugal pressure is greater than a predeterminied value only by which the pulley transmits an input torque from an engine. When the determination is affirmative, a lower limit of a duty ratio for operating a line pressure control valve is switched from a lower limit of a linear range to 0% duty ratio. Therefore, an actual transmissiou ratio control range is expanded while preventing an undershoot of the line pressure.

Control system for continuously variable transmission

An electronic transmission control system having a fail-safe system for an automotive vehicle with a continuously variable automatic transmission whose speed-change ratio is changeable continuously depending on vehicle speed and engine load, comprises a hydraulic modulator producing at least a regulated line pressure necessary to adjust the speed-change ratio hydraulically, a desired speed-change ratio arithmetic processing section for calculating a desired speed-change ratio based on the vehicle speed and the engine load, and a desired line pressure arithmetic processing section for calculating a desired line pressure based on the desired speed-change ratio and the engine load. Also provided is a fail-safe section comprises a comparing portion for comparing the desired line pressure to a predetermined line pressure threshold above which the desired line pressure is within an unreasonably high line pressure zone, a decision portion for deciding on the basis of a result of comparison of the comparing portion whether the desired line pressure is above the predetermined line pressure threshold, and a speed-change ratio retaining portion for retaining the speed-change ratio of the continuously variable automatic transmission unchanged, when the desired line pressure exceeds the predetermined line pressure threshold.

Electronic transmission control system with fail-safe system for

A control system comprises a line pressure control section which controls a line pressure applied to pulleys of a CVT according to an input load from the engine. When the input load is temporally increased, the line pressure is temporally increased by a pressure increasing section. After the line pressure is held for a predetermined time, the temporally increased line pressure is slowly decompressed by a step amount which is set small according to the increase of a transmission ratio of the CVT. This slow decompression of the line pressure suppresses the generation of vibrations of a drive system. Further, when an anti-skid control apparatus is operating or when a start clutch is engaged by the increase of the line pressure, the slow decompression is cancelled to smoothly execute their operations.

A control system for a CVT comprises a controller arranged to compute an engine revolution condition on the basis of an engine revolution speed indicative signal, to compute actual and estimated engine outputs on the basis of the engine revolution condition, to compute a rotational change condition of the drive system, to compute an actual input load change amount caused by the inertia by multiplying the actual rotational change condition detection value by a predetermined inertial constant, to compute an estimated input load change amount by multiplying the estimated rotational change condition detection value by a predetermined inertia coefficient, to select larger one of the actual input load change amount and the estimated input load change amount as the input load change amount for outputting a command signal, and to output the command signal to a line pressure duty valve on the basis of the engine output and the selected input load change amount so as to further accurately control a line pressure.

Line pressure control system for continuously variable transmission

In a continuously variable transmission (CVT) for a vehicle wherein a belt of V-shaped cross-section is looped around a drive pulley and a driven pulley respectively having grooves of identical shape to this belt, and the width of the groove of each pulley is varied according to a supplied oil pressure, an oil pressure when an accelerator pedal is released is maintained at or above a predetermined value. The oil pressure is controlled according to a torque input to the drive pulley, and the input torque varies according a depression amount of the accelerator pedal. As a result, the speed change ratio easily varies due to insufficient oil pressure when the accelerator pedal is released. This invention stops decline of oil pressure when the accelerator is released, and thereby prevents variation of the speed change ratio due to release of the accelerator pedal. This is especially useful when the speed change ratio of the transmission has been fixed by the driver in a manual speed change mode.

Controller and control method for continuously variable transmission

A method and apparatus for controlling a transmission for use with an automotive vehicle including an engine. The transmission coupled to the engine for transmitting a torque inputted thereto from the engine to produce an output torque at a continuously variable speed ratio. A target value for the speed ratio is calculated based on vehicle operating conditions. A rate at which the speed ratio changes to the calculated target value is calculated. An upper limit for the rate is calculated to satisfy such a condition that the transmission input torque is less than a maximum value below which there is no danger of damaging the transmission. The rate of change of the speed ratio is limited to the upper limit when the calculated rate of change of the speed ratio is greater than the upper limit.

Continuously variable transmission control method and apparatus

A control system for an engine-CVT drivetrain controls torque transmitting capacity of a lock-up clutch in response to drop of operator's power demand to keep hydraulic drive of a fluid coupling operable until a predetermined period of time passes after the subsequent increase of operator's power demand.

Engine-CVT drivetrain control system

A park lock arrangement for use in a continuously variable transmission including a housing, an end cover and a casing having one end portion coupled with the housing and the opposite end portion coupled with the end cover. The casing has an inwardly recessed portion to define a reduced container space. A follower shaft supporting a follower pulley has one end portion rotatably supported on the end cover and the opposite end portion extending into the housing. A driver gear is mounted on the opposite end portion of the follower shaft. A parking gear is disposed on the follower shaft between the follower pulley and the driver gear. A control shaft extends through the reduced container space and has one end portion projecting outwardly from the inwardly recessed portion of the casing. The control shaft drivingly supports a park lock mechanism for locking the parking gear. The park lock mechanism is disposed within the reduced container space.

Park lock arrangement for continuously variable transmission

A control system for an engine-CVT drive-train includes a ratio control element positionable to various command positions in response to a rate of change per unit time of CVT ratio determined by a controller to establish various CVT ratios. The controller decreases the rate of change per unit time of CVT ratio as the rate of change per unit time of the position of a gas pedal toward a release position thereof increases.

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Isehara, Japan

Hirofumi Okahara