Abstract: A hydraulic control apparatus of automatic transmission comprising a hydraulic pressure source, hydraulic paths, hydraulic servos for operating friction elements which are coupled with the hydraulic source and the hydraulic paths, a control device arranged on the hydraulic paths for operating engagement release through supply/removal of hydraulic pressure to the hydraulic servos and valves which are arranged on the hydraulic path for cutting off hydraulic pressure from the hydraulic pressure source to the hydraulic servo with hydraulic pressure in the downstream side of the control means as signal pressure.

Abstract: A learning controller makes learning correction based on a time tST between start of a shift control routine and detection of start of a change in rotational speed of the transmission input shaft and further based on the amount of rotational speed change &ohgr;S′ at the detected start of the rotational speed change. When the time tST is longer than a basic time and when the rotational change amount &ohgr;S′ is too large, it is determined that a servo piston has not been sufficiently advanced and the shift control is corrected so that the time tST is lengthened. When the time tST to the detected start of the rotational speed change &ohgr;S′ is too small, it is determined that, while the piston has been advanced properly, the target engagement pressure PTA in torque phase control is too low because of a miscalculation, and the shift control is corrected so that the target engagement pressure is raised.

Abstract: In a multiple speed-change operation for switching between an up-shift operation and a down-shift operation, engine torque control is adapted to an actual change in speed-change state, whereby an abrupt change in rotational speed of the input shaft is prevented. One embodiment relates to a speed-change operation from the second speed to the third speed, wherein the engagement-side hydraulic pressure B4 rises and the release-side hydraulic pressure B5 drops, the rotational speed NT of the input shaft changes from a second speed state toward a third speed state and the engine torque TE is reduced by a predetermined amount TCU. If a command to perform a speed-change operation from the third speed to the second speed is issued during the aforementioned speed-change operation from the second speed to the third speed, control of the hydraulic pressures is switched to the speed-change operation from the third speed to the second speed.

Abstract: A hydraulic control apparatus for automatic transmissions, capable of adapting the apparatus to a change in the specifications for a lockup clutch which causes the relationship between the supplying and discharging of a hydraulic pressure for a lockup control operation to be reversed with respect to the connection of oil passages. A valve body of the hydraulic control apparatus is formed by laminating at least two members on each other, and has a valve for regulating a hydraulic pressure supplied to a lockup clutch of a hydraulic transmission unit, a control unit for applying a signal pressure to the pressure regulating valve, a source pressure oil passage for supplying a basic pressure for a pressure regulating operation, and drain oil passage communicated with a drain port. The pressure regulating passage is provided at both sides of a port, which communicates with a lockup oil chamber via an oil passage, with a port communicating with an oil passage, and a port communicating with another oil passage.

Abstract: A hydraulic servo includes a cylinder, a piston and a rod. The piston divides the interior space of the cylinder between a closed hydraulic chamber and a back chamber which has an opening to the interior space of an automatic transmission. The rod is slidably mounted in the piston for relative movement through a predetermined distance. A frictional engagement element is engaged by the rod which is extended from one end of the cylinder by applying a hydraulic pressure to the hydraulic chamber. A passage is provided between the piston and the rod which is opened or closed by the relative movement between the piston and rod so that the hydraulic chamber and the back chamber are connected or disconnected. A valving arrangement (“closer”) closes the passage at the end of the return stroke of the piston toward the hydraulic chamber.

Abstract: A reduction in the weight and size of a speed-change mechanism is obtained by shortening a high-torque transmission system. The speed-change shock is attenuated by reducing an inertia torque in a muilti-stage vehicular automatic transmission. The vehicular automatic transmission is equipped with a planetary gear set that receives a decelerated rotation and a non-decelerated rotation as inputs and outputs a plurality of speed-change rotations, a reduction planetary gear, an input shaft that passes through an inner side of the planetary gear set, first and third clutches that couple the input shaft to two different speed-change elements of the planetary gear set respectively through the reduction planetary gear in an engageable and disengageable manner, and a second clutch that couples the input shaft to the other speed-change element of the planetary gear set in an engageable and disengageable manner.

Abstract: An automatic transmission comprises a reduction planetary gear, two clutches transmitting a decelerated rotation transmitted from the reduction planetary gear, and a planetary gear set comprising two elements to which the decelerated rotation is inputted through the two clutches. The reduction planetary gear and the two clutches are arranged in one side of the planetary gear set. The second clutch is closer to the planetary gear set than the clutch. The input side member of the first clutch is connected to an output element of the reduction planetary gear and the input side member of the second clutch. The output side member of the first clutch is extended through the radial inner space of the second clutch and connected to one of the two elements of the planetary gear set. Thus, no member is arranged in the radial outer side of the both clutches, and the both clutches are radially enlarged.

Abstract: An automatic transmission, which establishes automatic shifts in a multiple gear stages by selectively inputting a plurality of input rotations to a planetary gear set, includes first and third clutches connected through a reduction planetary gear to an input shaft and transmits a decelerated rotation to the planetary gear set and a second clutch directly connected to the input shaft and transmits a non-decelerated rotation to the planetary gear set. The reduction planetary gear is arranged on the end of a boss portion of a transmission case wall and the one element is fixed to the end of the boss portion, hydraulic servos of the first and third clutches are arranged on the boss portion, a hydraulic servo of a second clutch is arranged in the other side of the reduction planetary gear from the hydraulic servos, and the hydraulic paths for the hydraulic servos are formed in the boss portion.

Abstract: In a disengagement side control, in a power on state, a disengagement side pressure P.sub.W is output, P.sub.W being set higher than a base pressure dependent on input torque, and a disengagement side frictional engagement element is engaged and maintained. In a power off state, a disengagement side pressure lower than the base pressure is output, and the disengagement side frictional engagement element slips. In the disengagement side control, when the vehicle driving state is changed from the power off state to the power on state, the disengagement side pressure P.sub.W is changed from that for a slip state to that for a maintain state.

Abstract: An automatic transmission establishing multiple gear stages includes a reduction planetary gear, at least two clutches transmitting a decelerated rotation transmitted from the reduction planetary gear, and a planetary gear set inputted the decelerated rotation transmitted through the two clutches. The reduction planetary gear and the two clutches are arranged in one side of the planetary gear set. The reduction planetary gear is arranged between the clutches.

Abstract: An automatic transmission includes a planetary gear set inputted a decelerated rotation and a non-decelerated rotation and outputting a plurality of shift rotations, a reduction planetary gear, an input shaft, first and third clutches which are able to engage/disengage for connecting the input shaft through the reduction planetary gear to two different decelerated rotation input elements of the planetary gear set individually, and a second clutch which is able to engage/disengage for connecting the input shaft to a non-decelerated rotation input element. The first clutch, the third clutch and the reduction planetary gear are arranged together, and the second clutch is arranged in the other side of the planetary gear set.

Abstract: When a shift to a second gear ratio (second ratio) is determined during a shift control for a first shift (shift from fourth ratio to third ratio), the process status, or circumstances, of the first shift is determined using a hydraulic pressure for a fourth brake being engaged at the determination. When the process status, that is, the process circumstances, is in early phase, the first shift is interrupted and shift control for the direct shift to the second ratio (shift from fourth ratio to second ratio) is performed (first shift pattern). When the process status is in a late phase, the first shift control is continued, and after ending of the first shift control, the control for the shift to the second gear ratio (shift from third ratio to second ratio) is performed (second shift pattern). In the case of power off state, the second shift pattern is performed irrespective of the process status.

Abstract: When a vehicle driving state of an automatic transmission is changed to a power-off state from a power-on state during a down shift involving the disengagement of one friction element and the engagement of another friction element, a disengagement side pressure PA is reduced rapidly by a feedback control based on the change in gear ratio because of a reduction of an input torque. The disengagement side pressure control is unable to complete change of the gear ratio to complete the down shift. When the disengagement side pressure is reduced to a value less than a return spring load pressure PG or when the gear ratio change has not achieved a basic value in a predetermined time, the down shift control is changed from primary control by the disengagement side pressure control to primary control by an engagement side control so that the gear ratio change is completed by control of the engagement side pressure.

Abstract: The present invention prevents shift shock and reduces time required to execute the complete speed change operation in the case where a second speed change is commanded while a first speed change operation is still in progress. If a down-shift to a first speed stage is commanded during an up-shift operation from the first to the second speed, the hydraulic pressure in the second speed change operation is controlled in accordance with the state of the first speed change operation at the time of generation of the command for the second speed change. For example, if a down-shift to the first speed stage is commanded during the torque phase of an up-shift operation from first to second speeds, namely, before change in the rotational speed of the input shaft has started, only completion control of the down-shift operation is executed.

Abstract: A control apparatus executes appropriate speed change control under any operating conditions encountered during an up-shift by change-over, without requiring an increase in control logic. Engagement side hydraulic pressure is swept up as a result of an arithmetic operation in torque phase speed change control. Disengagement side hydraulic pressure is calculated by initial speed change control, dependent on the engagement side hydraulic pressure. The engagement side hydraulic pressure is directly controlled and the disengagement side hydraulic pressure is indirectly controlled, i.e. responsive to the engagement side control. Consequently, the same control scheme can be executed regardless of power-on state or power-off state and regardless of vehicle operating conditions.

Abstract: In a driven state, a hydraulic pressure of disengagement side is set at a stroke pressure, a one-way clutch in an operating state is over-run, an engine rotation speed is in an idle state, and an automatic transmission is in a neutral state. In a drive state, the hydraulic pressure of disengagement side is controlled so that a difference between an engine rotation speed and an input rotation speed reaches a difference between the both rotation speeds at a start of the shift control. In a state of a synchronized rotation after the shift, the hydraulic pressure of disengagement side is controlled so that the input rotation reaches the synchronized rotation.

Abstract: If a shift to the 3rd speed is decided during the 5th-4th speed shift, in which the hydraulic servo for a second clutch is released by pressure regulation control, a changeover valve is switched by a solenoid valve so that the fluid pressure P.sub.C2 from the pressure regulating valve is conducted to a third clutch hydraulic servo. Thereby, the third clutch hydraulic servo pressure P.sub.C3 stands by at a predetermined engaging pressure P.sub.H and, at the same time, the servo-start of a fourth brake fluid pressure P.sub.B4 is performed by another pressure regulating valve. Meanwhile, the fluid pressure P.sub.C2 is released by an accumulator. After the servo-start ends and the 4th speed is established, the 4-3 speed shift control is performed, thus preventing shift shock and reducing shift duration.

Abstract: When a vehicle is halted with the transmission in a forward drive range, an input clutch is disengaged to enhance the fuel efficiency and, at the same times a hill-hold brake is engaged to prevent the vehicle from rolling backward on a steep up-slope. At that time, the hydraulic pressure P.sub.C-1 of the input clutch C1 is gradually reduced by .DELTA.P.sub.CIR (P.sub.C-1 =P.sub.C-1 -.DELTA.P.sub.CIR) while the hydraulic pressure P.sub.B-1 of the hill-hold brake B1 is increased gradually so as to satisfy an equation P.sub.B-1 =K1+K2 X e where .DELTA.P.sub.cir is a change in hydraulic pressure which is required for gradually disengaging the first clutch C1, K1 is a hill-hold brake pressure at which braking resistance begins, K2 is hill-hold brake pressure producing a fully braked condition, and e is the input/output rotational-speed ratio of a torque converter Subsequently during start of vehicle movement, the hydraulic pressure P.sub.C-1 of the input clutch C1 is gradually increased (P.sub.C-1 =p.sub.C-1 +.

Abstract: In power-on, high-vehicle-speed and high-torque conditions, a control unit sets a torque allotment ratio such that a main clutch bears all the torque. Thereby, the input shaft rotational speed is increased by controlling solely the main clutch releasing pressure. In power-on and low-torque or low-vehicle-speed conditions, the control unit sets a torque allotment ratio for the main clutch torque and the sub-clutch torque to 1:1. Thereby, control of the main clutch releasing pressure and control of the sub-clutch engaging pressure simultaneously proceed in parallel to produce a change in the input shaft rotational speed without a time lag. The hydraulic control apparatus thus conducts proper downshift control for a shift involving clutch engagement changeover, under all vehicle running conditions, without need for additional control logic.

Abstract: A hydraulic servo unit for a vehicular power transmission system having a helical gear, including a clutch for connecting predetermined rotary elements to each other and a hydraulic servo for applying the clutch, the hydraulic servo including a cylinder, a piston fitted in the cylinder, a push member abutting against the piston through a bearing for transmitting the push force of the piston to the clutch, and a return spring for the piston, one of the rotary elements including a reaction member opposed to the push member for transmitting the push force of the piston to a case, and the cylinder is a stationary cylinder formed in the case. Further, the return spring is arranged between the push member and the reaction member and is loaded to apply a load higher than the thrust force of the helical gear, as acting upon the reaction member.