Abstract: A vehicle powertrain includes an engine driven variable displacement pump and an accumulator. A switch network controls the flow of fluid among the pump, the accumulator, a line pressure circuit of a valve body, and the sump, enabling several operating modes. In a balanced operating mode, no fluid flows into or out of the accumulator. In a discharging mode, fluid flows from the accumulator reducing the power required by the pump to increase output torque or reduce fuel consumption. In a charging mode, fluid flows into the accumulator for later use. Fluid also flow into the accumulator in a high-torque mode in which the pump and switch network are set to intentionally increase the pump torque to assist in deceleration.

Abstract: In a non-forward range, the same gear position as a forward first gear position is established in a stepped transmission. A hydraulic controller includes a second linear solenoid valve and third linear solenoid valve that respectively supply hydraulic pressure to a second clutch and first brake, and a selector valve that is provided in an oil passage upstream of the second and third linear solenoid valves and that switches between a state where hydraulic pressure is supplied to the oil passage and a state where supply of hydraulic pressure is cut off. When the non-forward range is set or when a vehicle is moving backward, the selector valve cuts off supply of hydraulic pressure to the oil passage. Thus, when there is a failure in the second or third linear solenoid valve, it is possible to suitably establish a gear position wherein the vehicle is not allowed to move backward.

Abstract: A method of shifting a vehicle drive-train transmission having frictional and interlocking shifting elements which are engageable to obtain various gears. When shifting from a current gear to a target gear, in which the interlocking shifting element is engaged, if after the shift starts it becomes necessary to engage the current gear in the transmission while engaging the interlocking shifting element, a current operating condition of the interlocking shifting element is determined. If the current operating condition of the interlocking shifting element indicates that engagement can be interrupted and the interlocking shifting element can be disengaged, the interlocking shifting element is disengaged.

Abstract: A vehicle drive apparatus for supplying oil pressure to a hydraulic servo at restart of an engine. The vehicle drive apparatus includes an accumulator that accumulates the oil pressure, an electromagnetic switching valve that retains oil pressure of the accumulator when an oil pump is stopped, a switching valve control unit that controls opening and closing of the electromagnetic switching valve, and a restart determining unit that determines whether or not to restart the vehicle drive source from a stopped state. When it is determined by the restart determining unit to restart the vehicle drive source, the switching valve control unit is started so as to supply the oil pressure accumulated in the accumulator to the hydraulic servo. As a result, engine friction engagement elements are quickly engaged to enable starting of a vehicle.

Abstract: A hydraulic control system for actuating at least one torque transmitting device in a transmission includes a sump, a pump in communication with the sump, and an accumulator. A first control device and a second control device control the communication of hydraulic fluid between the pump, the accumulator, and the torque transmitting device.

Abstract: An improved on-coming clutch fill control method in which a model of the transmission hydraulic system is used for control purposes to accurately predict the achievement of on-coming clutch torque capacity based on a comparison of the modeled volume of supplied fluid to a reference volume representing the actual volume of the on-coming clutch, and in which the reference volume for each type of shift is adaptively adjusted based on input speed aberrations observed during shifting. If input speed flaring occurs due to an underestimated reference volume, the reference volume is adaptively increased based on the volume of fluid supplied to the on-coming clutch between the initial detection of flaring and a detection of maximum flaring.

Abstract: An improved shift control for a hydraulic automatic transmission in which the apply chamber of an on-coming clutch is filled in the preparation phase of the shift using a hydraulic flow rate model to estimate the volume of hydraulic fluid supplied to the apply chamber. In an initial portion of the fill interval, fluid is supplied to the apply chamber at a first elevated pressure, while continuously updating the fluid volume estimate. When the remaining un-filled volume of the apply chamber reaches a reference volume, the supply pressure is reduced to a second pressure at which the next phase of the shift is to be carried out. When the chamber volume is filled, the torque capacity of the clutch rises to a level corresponding to the second pressure, and the next phase of the shift automatically ensues.

Abstract: A control for determining the state of adjustment or misadjustment of a master friction clutch (14) in a vehicular automated mechanical transmission system (10). A system controller (24) receives input signals (26) indicative of the engaged or disengaged condition of the master clutch, the rotational speed of the transmission input shaft (IS) and the engaged or disengaged condition of the mechanical transmission (16). When the master clutch and the transmission both are disengaged, the rate of change of input shaft speed (dIS/dt) is compared to a predetermined reference value, and if the rate of deceleration of the input shaft speed is less than said reference value, significant master clutch misadjustment is determined and corrective action is initiated. Corrective action may include causing a display (48) to signal the operator that the master clutch is improperly adjusted and/or operating an input shaft brake (50) in a fault-tolerant mode.

Abstract: An up-shift control apparatus installed to an automatic transmission, where an up-shift is executed by disengaging a first friction element and by engaging a second friction element, includes an A/T control unit for deciding the up-shift, a gear ratio detecting unit for detecting a gear ratio of the automatic transmission, a discharging pressure control actuator, and an up-shift discharging pressure control unit. The up-shift discharging pressure control unit outputs a command to the discharging pressure control actuator to temporally increase the discharging pressure of the first friction element when the detected gear ratio becomes a preset gear ratio indicative of a time just before the end of the inertia phase during an up-shift.

Abstract: An automotive automatic transmission has an input shaft receiving a rotational force from an engine, an output shaft for outputting a rotational force to a vehicle driving wheel, a frictional engagement device having an adjustable engagement condition, and a transmission device for transmitting a rotational force from the input shaft to the output shaft at a gear speed ratio depending on the engagement condition of the frictional engagement device. A control apparatus for the automotive automatic transmission includes an engagement condition adjusting device for adjusting the engagement condition of the frictional engagement device by feeding a hydraulic pressure thereto in response to an instructed control amount.

Abstract: A hydraulic control system for an automatic transmission used in a vehicle, the hydraulic control system includes a pressure regulating part for regulating hydraulic pressure generated from a hydraulic pump to constant line pressure, a manual valve selectively supplying hydraulic pressure to a drive pressure passage, a reverse pressure passage, and a first and a second speed pressure passage. A pressure control part supplies standard pressure to solenoid valves which are duty-controlled by a transmission control unit. The pressure control part has a solenoid supply valve. A damper clutch control part controls a damper clutch of a torque converter. A pressure distributing part distributes an appropriate amount of pressure to friction members, and has shift valves and clutch valves. A torque pressure generating part reduces the line pressure so that it can be used for initial shifting control.

Abstract: An automatic transmission having a multiple ratio gearset arranged in series with an overdrive gearset wherein ratio upshifts and downshifts are effected by separate reaction brakes for each gearset, each brake being independently controlled to achieve an enhancement of shift quality using closed loop control of reaction brake pressure and high ratio clutch pressure as a function of turbine speed, output shaft speed, brake drum speed for the multiple ratio gearset and input shaft speed in establishing control of upshifts and downshifts.

Abstract: A multiple ratio transmission having a main gear unit with at least three forward driving ratios and a single reverse drive ratio and a simple planetary gear unit in series with the main gear unit, the simple planetary gear unit being downshifted and the main gear unit being upshifted on an upshift from a first intermediate ratio to a higher intermediate ratio, the simple planetary gear unit being upshifted and the main gear unit being downshifted on a downshift from the higher intermediate ratio to the first intermediate ratio, the initiation of the inertia phase of the upshifting mean gear unit on an overall automatic transmission ratio upshift triggering the beginning of the release of a reaction element of said simple planetary gear unit upon downshifting of said simple planetary gear unit.

Abstract: An automatic transmission gear shift control system controls a transitional pressure level during a gear shift according to engine output conditions and correctively changes a rate at which the transitional pressure changes according to a time difference between an actual gear shift time and a target gear shift time when an engine output is less than a specified level. If the corrected rate is greater than a specified rate, then the transitional pressure level is increased. According to the control system, even when a drop in the transitional pressure does not cause a change in shifting time, a shifting time learning control is properly conducted.

Abstract: 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.

Abstract: An automotive automatic transmission has a hydraulically operated clutch device and an electronic control unit. The clutch device includes drive and driven clutch plates and a piston for pressing the drive and driven clutch plates to establish an engagement therebetween when an oil chamber for the piston is fed with a certain amount of fluid. In order to control the clutch device, the following steps are employed, which are (a) issuing a first instruction signal to the clutch device; (b) feeding the oil chamber with the fluid by an amount which is sufficient for moving the piston from a rest position to a critical position which is ready for effecting the actual pressure against the drive and driven clutch plates; (c) issuing a second instruction signal to the clutch device; and (d) increasing the hydraulic pressure in the oil chamber to cause the piston to instantly establish the engagement between the drive and driven clutch plates.

Abstract: An automatic transmission control system includes a hydraulic circuit for controlling coupling pressure supplied to frictional coupling elements of the automatic transmission, which are selectively coupled and uncoupled so as to shift the automatic transmission into desired gears. The hydraulic circuit has a solenoid valve, for regulating a principal hydraulic pressure to provide a control pressure in accordance with vehicle driving conditions. The coupling pressure, supplied to a frictional coupling element, is regulated by a regulating valve in accordance with a control pressure level, and during shifting of the automatic transmission, is supplied through an accumulator whose back pressure is controlled in accordance with the control pressure by a control valve.