Abstract: A control system for an automatic transmission includes a first frictional engagement element and a second frictional engagement element; and a first hydraulic servo for controlling the application/release of the first frictional engagement element and a second hydraulic servo for controlling the application/release of the second frictional engagement element. A regulator valve regulates the oil pressure to the first hydraulic servo. A signal pressure is applied to the regulator valve to establish a predetermined gear stage by switching the applied/released states of the first frictional engagement element and the second frictional engagement element by feeding/releasing oil pressure to/from the first hydraulic servo and the second hydraulic servo.

Abstract: A friction brake band actuating system for automatic transmissions operative for obtaining smooth self-synchronized freewheeler type shifts without the use of one-way roller or sprag clutches. The band functions normally like a conventional brake band providing engine braking while the vehicle is coasting. For both upshifting and downshifting, the actuating system is staged in a one-way mode at the beginning of the shift event. In the one-way mode the self-synchronizing brake band utilizes the band reaction force to regulate a common pressure, which is acting on the apply piston and also on a reaction piston provided for counteracting the force at the band anchor end. The resulting torque capacity of the band varies in direct relationship with the torque the band is transmitting.

Abstract: An arrangement for controlling an automatic selector device of a change-speed gearbox has two selecting connections engageable alternately by selecting actuators operated by pressure medium can be actuated into two non-transient and two transient selector conditions. This alternate engageability is provided by an electronic control unit by way of just one electromagnetic control valve. The arrangement also uses three pressure systems and two multi-way valve arrangements.

Abstract: An electronic and hydraulic system of a five speed automatic transmission adapted to establish five forward and one reverse gear ratios by way of effecting selective engagement and disengagement of friction elements comprises an oil pump for producing a pressurized working fluid, a manual selector valve manually operated for distributing the working fluid to forward and reverse fluid lines, first to fourth shift valves for directing the working fluid to one of the friction elements, first to fourth solenoid valves associated with the first to fourth shift valves, respectively, for controlling positions of the shift valves in correspondence to a vehicle speed and a throttle opening degree, second to fourth speed valves each position-controlled by the first to third shift valves to change flow path of the working fluid and an overdrive unit valve position-controlled by the fourth shift valve.

Abstract: The present invention relates to an adaptive control method for an automatic transmission. The method includes the steps of:(a) commanding a predetermined clutch to fill in accordance with a plurality of clutch fill parameters;(b) determining the actual time to completely fill the clutch;(c) comparing the actual fill time with a predetermined fill time; and(d) adjusting at least one of the plurality of clutch fill parameters in response to the comparison in order to modify the clutch fill period during subsequent shifts to the predetermined clutch. Accordingly, the present invention adapts future shifts based on past shifts to improve the shift quality of the transmission.

Abstract: The present invention is directed to methods and systems for improving the operation of a transmission for an automotive vehicle, and in particular the transmission as installed by the original automobile manufacturer. The methods and systems of the present invention modify the original hydraulic fluid circuits of the automotive transmission provided by the automobile manufacturer to enable the transmission to select any available ratio at any time, and to enable the transmission to produce quick applies and releases for racing applications with only minimum ratio sharing or overlap.

Abstract: A changeover valve is provided on an upstream side of solenoid valves for hydraulic engaging elements. The changeover valve is urged to the closed position by the hydraulic oil pressure of a plurality of hydraulic engaging elements which are concerned with the speed changing. At the time of failure in which three or more of the hydraulic engaging elements are simultaneously engaged, the changeover valve is changed over to the closed position to thereby lower the hydraulic oil pressure in the hydraulic engaging elements on the downstream side of the changeover valve, whereby the simultaneous engagement is prevented. In the closed position, a hydraulic oil pressure of a predetermined pressure is inputted to the changeover valve via an oil passage. The chattering of the changeover valve is thus prevented even if the hydraulic oil pressure in the hydraulic engaging elements may be lowered.

Abstract: A diagnosing apparatus for diagnosing a vehicle automatic transmission system including an automatic transmission having frictional coupling devices, and solenoid-operated valves for controlling the frictional coupling devices to shift the automatic transmission according to shift commands generated by a control device, the apparatus including a speed detector for detecting an engine speed of the vehicle, a device for determining a reference range of the engine speed within which the engine speed is expected to fall when the transmission is placed in a position selected by a shift command, a device for determining whether a predetermined running condition of the vehicle is satisfied, and a defect detector for determining whether there exists a defect associated with the automatic transmission system, depending upon whether the detected engine speed is held within or outside the determined reference range when the predetermined vehicle running condition is satisfied.

Abstract: A control system for a shift-by-wire automatic transmission, comprises: a first range changing valve for having an input port switched to communicate with a first output port and a second output port; a second range changing valve for causing the first input port connected with the first output port to communicate with two range ports selectively and for causing a second input port connected with the second output port to communicate with at least another of the range ports selectively; and a drive mechanism for switching and operating the first and second range changing valves. Further comprised are: a fail detector for detecting a failure that either of the first range changing valve and the second range changing valve fails to be switched; and a fail controller for outputting an instruction signal to the drive mechanism to change the range by actuating the switchable one of the range changing valves if the fail detector detects the failure.

Abstract: A system and method for controlling the bypass clutch of an automatic transmission includes an electronic microprocessor, an electronic memory accessible to the microprocessor, solenoid-operated bypass valve, pressure actuated bypass clutche, a variable force solenoid-operated bypass valve, a torque converter bypass friction clutch, and control algorithms that produce output signals to control the state of the solenoid-operated valve. The vehicle speed at which the bypass clutch engages and disengages, according to a reference schedule, is compensated for loss of engine torque at conditions that differ from the conditions at which the reference schedule is defined. Vehicle speed is compensated for torque variation with reference to the ratio of current calculated engine torque divided by current engine output torque.

Abstract: A hydraulic control for an automatic transmission is composed of a gear shift mechanism having first and second frictional engagement elements, a hydraulic control unit for the engagement elements, and an electronic control unit for the hydraulic control unit. The first element is engaged to achieve a first speed stage and the second element is engaged to achieve a second speed stage faster than and closest to the first speed stage. The hydraulic control unit has a first directional control valve for switching the feeding and discharge of hydraulic pressure between the first and second engagement elements, responsive to a first solenoid signal from the electronic control unit. A second directional control valve is adapted to be switched by a second solenoid signal from the electronic control unit to achieve a third speed stage yet faster than the second speed stage. The first engagement element has a discharge line connected to a drain line via the second directional control valve.

Abstract: In one aspect of the present invention, an electronic shift control for a powershift transmission is disclosed. The transmission includes a plurality of speed and direction changing clutches. A plurality of pressure control valves are individually connected to the clutches. A hydraulic pump delivers pressurized hydraulic oil to predetermined pressure control valves to meter hydraulic fluid in response to receiving a clutch command signal. The method produces a shift from a first transmission ratio to a second transmission ratio through disengagement of an off-going clutch associated with the first transmission ratio and engagement of an on-coming clutch associated the second transmission ratio. The method includes filing an on-coming speed clutch, releasing an off-going direction clutch in response to the on-coming speed clutch being filled, and thereafter, gradually increasing the on-coming speed clutch pressure to engage the speed clutch.

Abstract: An automatic transmission control method and apparatus for a vehicle includes a first gear change mechanism in which an input shaft is connected to an output shaft of a fluid coupling and a rotational speed of the output shaft of the first gear change mechanism is changed by selectively controlling hydraulic oil supplied to and discharged from a plurality of first frictional engaging elements. It further includes a second gear change mechanism in which an input shaft is connected to the output shaft of the first gear change mechanism, the output shaft is connected to a driving wheel member and an output shaft rotational speed of the second gear change mechanism is controlled by selectively controlling the hydraulic oil supplied to and discharged from a plurality of second frictional engaging elements.

Abstract: A valve (36) for controlling pressure supplied to a friction clutch (32) of an automatic transmission includes several valve spools (38,40,44) each formed with control lands located within a bore (42) opening to various ports (60,66,68,72,76,80) that are supplied selectively with line pressure depending upon the operating state of the transmission. The valve operates in a primed condition, whereby a predetermined low pressure is supplied continually to the friction clutch. The valve supplies the clutch with a higher pressure that operates to stroke the clutch cylinder and friction element and thereafter regulates clutch pressure in accordance with changes in pressure in one of the ports. The clutch is stroked rapidly because the valve provides a relatively unrestricted supply of pressurized fluid through one of its inlet ports. After the clutch free-pack clearances are taken up, the valve restricts the clutch stroke against a cushion spring by opening the clutch cylinder to an orificed supply circuit.

Abstract: A hydraulic control system for an automatic transmission comprises a plurality of shift valves which connect a first hydraulic passage communicating with an N+2 speed apply chamber to a second hydraulic passage communicating with an N+1 speed release chamber upon N speed, where N is a whole number equal to or greater than 1.

Abstract: A hydraulic control system for controlling an automatic transmission includes a regulating valve which reduces a line pressure in accordance with a control pressure, provided in accordance with vehicle driving conditions, to provide a coupling pressure for coupling a specific one of frictional coupling elements of the automatic transmission. The regulating valve is enabled to provide the coupling pressure independently from the control pressure when a coupling pressure for another frictional coupling element higher than a specified level.

Abstract: A fail-safe hydraulic control system for an automatic transmission for a vehicle is provided.

Abstract: In an automatic transmission including first and second planetary gear sets and a plurality of friction elements, during an up-shift and a time after the up-shift, a hydraulic pressure of a released friction element is kept at a predetermined value corresponding to the biasing force of a return spring set in the control valve of the friction element for a predetermined time after the end of the up-shift. When a down-shift is carried out immediately after the above-mentioned up-shift, the engagement of the released friction element is rapidly carried out since the hydraulic pressure of the friction element is kept at the predetermined value.

Abstract: Disclosed is a clutch changeover circuit suitably used for a multi-stage stationary non-stage transmission. Valve bodies of pressure regulating valves (211, 221, 231, 241) are respectively provided with throttle passages (311, 321, 331, 341) communicating therewith in such a manner that hydraulic oil flows to the clutch sides when they are closed, since the sliding of the clutches or damage thereto can occur if pressure regulating valves having good override characteristics are used. Accordingly, at the time of changing over the clutch, since hydraulic oil flows at least by a portion corresponding to the rate of flow of leaking oil, it is possible to prevent the clutches from sliding or becoming damaged while using regulating valves having good override characteristics.

Abstract: A power transmission for driving a vehicle wherein a high-low speed changer is disposed between an engine and a primary speed change mechanism. The speed changer comprises a planetary gear mechanism provided between an input shaft and an output shaft, a speed increasing clutch for causing the gear mechanism to effect a speed increase, and a direct coupling clutch for coupling the input shaft to the output shaft via the gear mechanism without speed change. Since the torque transmitted to the speed change mechanism is small, the transmission can be compact in its entirety.

Abstract: Disclosed is a clutch changeover circuit suitably used for a multi-stage stationary non-stage transmission. Valve bodies of pressure regulating valve (211, 221, 231, 241) are respectively provided with throttle passages (311, 321, 311, 341) communicating therewith in such a manner that hydraulic oil flows to the clutch sides when they are closed, since the sliding of the clutches or damage thereto can occur if pressure regulating valves having good override characteristics are used. Accordingly, at the time of changing over the clutch, since hydraulic oil flows at least by a portion corresponding to the rate of flow of leaking oil, it is possible to prevent the clutches from sliding or becoming damaged while using regulating valves having good override characteristics.

Abstract: A hydraulic controller for an automatic transmission, having a band brake having a large stopping force based on a self-boosting effect against rotation in a self-binding direction and having a comparatively small stopping force against rotation in the unbinding direction, a modulator valve for producing a modulator pressure by reducing a line pressure, a band brake hydraulic servo having a brake engaging hydraulic chamber and a brake releasing hydraulic chamber. A line pressure is supplied to the band brake hydraulic servo to stop rotation in the self binding direction when a predetermined transmission speed is selected. The line pressure is also supplied the band brake hydraulic servo to stop rotation in the unbinding direction when another transmission speed is selected. A modulator pressure is supplied to the brake engaging hydraulic chamber to stop the rotation in the self-binding direction of the band brake and to allow the rotation in the unbinding direction when an intermediate speed is selected.

Abstract: A transmission control system for controlling a transmission. The system has a main transmission with a speed changing mechanism and an output shaft, a substransmission connected to the output shaft, and a control system for receiving outputs from a number of sensors which sense the running state of the vehicle. The control system itself has two outputs, there being two separate hydraulic controls connected to the two system outputs, respectively. The two hydraulic controls control the speed changing mechanisms of the main and subtransmissions, respectively. Also provided is a hydraulic pressure source which supplies a working fluid to the two hydraulic controls. The control system determines whether the main and subtransmissions are in a transient period of the speed changing operation and, as long as one of the two transmissions is in the transient period, inhibits the speed changing operation of the other transmission.

Abstract: A sequence valve is interposed between the manual valve and the reverse clutch and arranged to control the communication therebetween. The valve is responsive to the pressure which develops in the low and reverse brake and establishes communication between the manual valve and the reverse clutch when the pressure prevailing in the low and reverse brake is such as to indicate that the brake is engaged to a predetermined degree.

Abstract: Herein disclosed is a brake system for use with an automatic transmission for braking a rotatable member such as a brake drum, which is accommodated in a casing and connected to the sun gear or the like of a planetary gear mechanism, by bringing a brake band having two ends into contact with the outer circumference with the rotatable member.