摘要:
Uncomfortable travel of a vehicle due to engine brake actions during the travel of the vehicle in traffic is prevented without using an one-way clutch within a transmission mechanism. An automatic transmission is composed of rotational elements that are braked at the time of establishing low stages, a brake that brakes the rotational elements, and control systems which control the oil pressure of the hydraulic servo in the brake. A band brake that creates differences in application forces, using self-energizing and deenergizing actions, serves as the brake, which is set to have an area in which the oil pressure during the drive is lower than the oil pressure during the non-drive, by setting the self-energizing direction as a direction of rotation of the rotational element during the drive and the deenergizing direction as an opposite direction of rotation of the rotational element during the non-drive. The control systems have a supplying mechanism which supplies oil to the hydraulic servo of the band brake at an oil pressure that is lower than the oil pressure during the non-drive and is equal to or higher than the oil pressure during the drive.
摘要:
A shift control system is provided for an automatic transmission having, connected in series, a secondary shifting unit, capable of being shifted between a high speed stage and a low speed stage, and a primary shifting unit which provides plural speed stages including a reverse speed stage. The secondary shifting unit can be set to the high speed stage upon a shift into reverse. The shift control system is equipped with a reverse range detector for detecting a shift from neutral to reverse range, a vehicle stop detector for detecting that vehicle is stopped, and a high speed stage command device for setting the secondary shifting unit at the high speed stage when, subsequent to a shift of the primary shifting unit into reverse, the vehicle is determined by a signal from the vehicle stop detector to have substantially stopped.
摘要:
A control system is provided for servo hydraulic pressure in an automatic transmission. Upon downshifting, one of first and second frictional engagement devices is released while the other is engaged. A directional control valve is provided to feed or drain servo hydraulic pressure to selectively engage or release the first and second devices. The hydraulic pressure is regulated by a pressure regulator under the control of an electronic control unit. Detectors are also provided to determine input rotation and torque, respectively. The regulator is interposed between the directional control valve and the engaged device. The regulator is controlled to maintain the servo hydraulic pressure at a predetermined value under the control of the electronic control unit until predetermined input rotation is detected and then to gradually raise the servo hydraulic pressure under the control of the electronic control on the basis of the value of input torque.
摘要:
A shift control system of an automatic transmission for setting a predetermined gear stage by applying first frictional engagement means and releasing second frictional engagement means, comprising: a pressure regulating mechanism for regulating an oil pressure to be fed to or drained from the first frictional engagement means; a failure detector for detecting a failure of an apparatus to participate in the regulation and control of the oil pressure which is to be fed to or drained from at least one of the first and second frictional engagement means: and a gear stage inhibitor for inhibiting the setting of the predetermined gear stage if the failure is detected by the failure detector.
摘要:
An automatic transmission control apparatus has a vehicle speed detector, an accelerator pedal operation detector, a brake pedal operation detector, a clutch hydraulic servo that is neutral-controlled, a brake hydraulic servo that is hill holding-controlled, and a control device for controlling the fluid pressure supplied to the two servos. The control device selectively changes the start timing of the fluid pressure supply control. If it is determined that the vehicle is stopped and that the vehicle is not on an uphill, the control device causes a pressure reducing device and a pressure supplying device to simultaneously start reducing the fluid pressure supply to the clutch servo and supplying fluid pressure to the brake servo, respectively. If it is determined that the vehicle is on an uphill, the control device causes the pressure supplying device to start supplying fluid pressure to the brake servo and, after a predetermined time period, causes the pressure reducing device to start reducing the fluid pressure supply to the clutch servo.
摘要:
An automatic transmission control apparatus has first and second hydraulic servos for engaging forward and reverse driving friction engaging elements, respectively, a fluid pressure control unit, a range shift detector, and an electronic control unit. When the forward driving range is selected, the fluid pressure control unit supplies a forward driving range pressure to the hydraulic servo via a changeover valve operated by a signal pressure from a normal open-type solenoid valve, when the signal pressure is drained. When the reverse driving range is selected, the electronic control unit outputs a signal to magnetize the solenoid valve. The solenoid valve is thus turned on to discontinue the drain. The control apparatus thus prevents low pressure in the reverse driving range pressure to prevent delay of engagement of the clutch.
摘要:
A control system for an automatic transmission having a running status detector for detecting the running status of a vehicle including an input torque from an engine; a running resistance estimator for estimating a running resistance on the basis of the running status of the vehicle; a running resistance comparator for comparing the estimated running resistance and a preset reference value; and a shift characteristic changing device for changing shift characteristics in accordance with the comparison result of the running resistance comparator. The automatic transmission control system further has a temperature sensor for detecting a temperature relating to the temperature of the engine and a decision device for determining a specific engine running status, in which the output of the engine drops, on the basis of an output signal coming from the temperature sensor. The running resistance comparator changes the reference value in accordance with the determination of the decision device.
摘要:
In an automatic transmission, a small-capacity second clutch that does not engage for reverse drive is mounted forward of a counter drive gear, and the other engaging elements of relatively larger capacity, that is, first and third clutches and first to third brakes, are disposed rearward of the counter drive gear, so that an axially extending space is formed between the counter drive gear and the second clutch, which space is utilized to accommodate a parking gear. Such an arrangement of engaging elements allows the counter shaft to be placed closer to the input shaft without the parking gear interfering with the second clutch, thereby enabling a more compact automatic transmission. Furthermore, since there is no need to relocate the counter drive gear rearward, the length of the counter shaft can be reduced, thereby enabling still greater compactness.
摘要:
An automatic transmission comprising a torque converter and a change speed transmission having a plurality of planetary gearsets and friction elements is provided with an input shaft supported by a transmission case. On the input shaft is mounted a small-diameter first drum. In the first drum are mounted a first clutch having a clutch piston, friction plates, separate plates and a clutch hub. On the input shaft is further mounted a large diameter second drum, in which are disposed a second clutch having a clutch piston, friction plates, separate plates and a clutch hub.The friction plates and separate plates in the second drum are disposed radially outside on top of the friction plates and separate plates in the first drum.
摘要:
A direct coupling clutch being assembled within a casing of a fluid coupling having an impeller mounted on the casing and a turbine supported on an output shaft of the fluid coupling. The direct coupling clutch includes a piston mounted slidably on a turbine hub in axial direction for engaging with and disengaging from a front cover of the casing and a damper device resiliently connecting the turbine hub and piston. The damper device includes an annular driven plate consisting of two guide plates secured concentrically with each other and having a first set and a second set of spaces arranged in double rows along two concentric circles, an annular drive plate having a set of openings arranged in a row along a first circle, a set of projections arranged in a row along a second circle, a first coil spring inserted in each of the first set of spaces and within each of the set of openings and a second coil spring inserted in each of the second set of spaces and between the projections. The first coil spring is continually compressed by the relative rotation of the drive and driven plates and the second coil spring having a greater spring constant than that of the first coil spring is compressed after the first coil spring has been compressed in a predetermined value.