摘要:
In a certain speed stage shifting of an automatic transmission of a vehicle including a speed change gear mechanism including rotary members such as gears and gear carriers and hydraulically operated friction engaging brakes and clutches adapted to provide various speed stages according to selective engagement and disengagement of the friction engaging brakes and clutches, the servo oil pressure of a first friction engaging brake is immediately lowered down to a stand-by pressure marginally higher than a threshold pressure bordering non sliding and sliding of the first friction engaging brake at the start of a change-over of a second friction engaging brake is and then, when a substantial change-over of the second friction engaging means started, the servo oil pressure is further lowered across the threshold pressure and thereafter periodically lowered by a decrement the magnitude of which may desirably be increased along with a lapse of time.
摘要:
A shift control system controls an automatic transmission of a vehicle wherein half-lock-up control for a lock-up clutch is executed when the running state of the vehicle is in a predetermined operative range. The shift control system includes a half-lock-up control inhibiting unit for inhibiting the half-lock-up control from being executed when the running state of the vehicle is held in a specific operative state even though the running state of the vehicle is in the predetermined range, a determining unit for determining whether or not the half-lock-up control is inhibited by the half-lock-up control inhibiting means, and a controlling unit for controlling the automatic transmission such that a low speed stage at which the half-lock-up control is easily executed is positively utilized when it is determined that the half-lock-up control is not inhibited by the determining unit, and moreover, controlling shift change of the automatic transmission such that a high speed stage having a gear ratio lower than that at the lower speed stage is positively utilized when it is determined that the half-lock-up control is inhibited by the determining unit.
摘要:
A five-speed automatic transmission includes a main transmission and an over-drive transmission of a front disposition type. The main transmission includes three sets of planetary gears, a clutch for engaging and disengaging speed-change elements of the planetary gear sets, and a brake for fixing and releasing the speed change elements, and provides for four forward speed ranges and one reverse speed range. In the over-drive transmission of a front disposition type, a speed change element of an over-drive planetary gear set connected to an input element of the main transmission is adapted to be engaged, disengaged and fixed for achieving either a directly coupled stage or an over-drive stage. The over-drive transmission releases the direct coupling for reverse driving operation. One of the clutches of the main transmission for achieving the directly coupled stage and one of the brakes for achieving the low speed stage are engageable in the reverse driving operation.
摘要:
An automatic transmission which includes a device for selecting and temporarily setting such one of other speed stages, if any, between a present speed stage and a target speed stage as can have a small number of fluctuating revolutions of rotary members of planetary gear sets of the automatic transmission and two or less frictional engagement elements to be switched.
摘要:
A shift control system for use in an automatic transmission having a gear train to be set to a plurality of gear stages of different gear ratios in accordance with the engagement/release states of a plurality of fricitional engagement devices. The gear train is enabled to set a predetermined gear stage in accordance with plural kinds of combination of the engagement/release of the frictional engagement devices. The shift control system comprises: an input torque detector for detecting input torque to be inputted to the gear train; a torque evaluator for evaluating the level of the input torque; and an engagement/release pattern selector for selecting the combination of engagement/release of the frictional engagement devices for setting the predetermined gear stage, on the basis of the result of the input torque evaluated by the torque evaluator.
摘要:
A shift control system for use in an automatic transmission which comprises: a plurality of frictional engagement components; and a gear train adapted to set a plurality of speed stages having different gear ratios in accordance with the combination for engagement/release of the frictional engagement components and enabled to select a combination for engaging and releasing any of the frictional engagement components as that for engagement/release of the frictional engagement components for setting any of the speed stages. The shift control system comprises: a detector for detecting the engagement failure of the frictional engagement components; an engagement/release pattern selector for selecting a combination for releasing any one of the frictional engagement components as the combinations for engagement/release of the frictional engagement components for setting any one of the speed stages, if the engagement failure of any one of the frictional engagement components is detected; and an output device for outputting an instruction signal for setting the selected combination for engagement/release of the frictional engagement components.
摘要:
A hydraulic control device is provided for automatic transmission in a vehicle such as an automobile. The transmission includes a combination of a gear mechanism and friction engaging devices which allows engagement of a particular first speed stage, such as first gear, and a particular second speed stage, such as second gear, according to selective engagement and disengagement of the friction engaging devices. Engine braking is not provided in the first speed stage, but is provided in the second speed stage when an under-D range is selected by the manual shift valve. Low coast upshifting is thus performed more smoothly. The shift from the first speed stage to the second speed stage is also completed more slowly than any other shift.