Abstract: A powertrain has an electro-hydraulic control mechanism that provides for the establishment of six forward speeds, a neutral condition and a reverse speed. The control system also permits operation in the fifth forward range if electrical power is discontinued when the transmission is operating in the third range or higher, and permits operation in the third range if the transmission is operating in the second range or lower when an electrical power discontinuance occurs. If an electric disconnect occurs, the reverse drive is available, neutral is available, and third forward drive is available from the reverse and neutral conditions. The drive-home functions described are provided through the use of a multiplex valve, default valve and a pair of solenoid valves. The multiplex valve and default valve also permit the controlling of two mutually exclusive torque transmitting devices through the use of a single trim valve.

Abstract: A powertrain has an electro-hydraulic control mechanism that provides for the establishment of six forward speeds, a neutral condition and a reverse speed. The control system also permits operation in the fifth forward range if electrical power is discontinued when the transmission is operating in the third range or higher, and permits operation in the third range if the transmission is operating in the second range or lower when an electrical power discontinuance occurs. If an electric disconnect occurs, the reverse drive is available, neutral is available, and third forward drive is available from the reverse and neutral conditions. The drive-home functions described are provided through the use of a multiplex valve, default valve and a pair of solenoid valves. The multiplex valve and default valve also permit the controlling of two mutually exclusive torque transmitting devices through the use of a single trim valve.

Abstract: The power transmission has a fly-by-wire electro-hydraulic control mechanism that controls the engagement and disengagement of the range clutches in both forward and reverse operation. In forward operation, the control mechanism permits continued vehicle operation in the third forward range should electrical discontinuance occur during the first through fourth forward ranges, and in the fifth forward range should electrical discontinuance occur in the fifth or sixth forward range. Also, the control mechanism includes two logic valves and a forward on/off solenoid valve that permits the logic valves to control three torque-transmitting mechanisms with the use of two trim solenoid valves.

Abstract: The power transmission has a fly-by-wire electro-hydraulic control mechanism that controls the engagement and disengagement of the range clutches in both forward and reverse operation. In forward operation, the control mechanism permits continued vehicle operation in the third forward range should electrical discontinuance occur during the first through fourth forward ranges, and in the fifth forward range should electrical discontinuance occur in the fifth or sixth forward range. Also, the control mechanism includes two logic valves and a forward on/off solenoid valve that permits the logic valves to control three torque-transmitting mechanisms with the use of two trim solenoid valves.

Abstract: An improved and self-diagnosing shift pressure regulator apparatus for an automatic shift transmission provides a diagnostic output that reliably and timely detects initiation and cessation of fluid supply to a friction element. The regulator apparatus includes a pressure regulator valve responsive to an electronically developed pilot pressure, and a diagnostic switch. The pilot pressure positions the pressure regulator valve in one of three states—ON, TRIM, and OFF—and the diagnostic switch is continuously activated by a control pressure whenever the pressure regulator valve is in the TRIM or ON states.

Abstract: An improved control for an automatic transmission garage shift, wherein a dynamic model of the transmission is used to estimate the transmission input torque during the shift and to schedule the on-coming clutch pressure in accordance with the estimated input torque to achieve a desired input shaft trajectory. The transmission input torque is estimated based on two different methodologies —one suited to steady-state engine idle conditions, and the other suited to engine output torque transient conditions. A fuzzy summation of the input torques provided by the two methodologies is utilized in transitions between the two conditions. Shift quality variations due to variations in mechanical and/or hydraulic stiffness are minimized by a pause or hold interval inserted between the end of the fill period and the initiation of on-coming clutch pressure control, which results in a reasonably consistent degree of perceived transmission-to-transmission hydraulic and mechanical compliance.

Abstract: A power transmission includes a plurality of torque transmitting mechanisms controlled by an electro-hydraulic control system to provide a reverse drive ratio, a neutral condition and a plurality of forward drive ratios. The electro-hydraulic control has three shift valves, two variable pressure control valves, and a manual control valve. Each of the shift valves have a hydraulically on position, established by a respective solenoid valve, and a hydraulically off position, established by a spring. The manual control valve is moveable to a neutral condition, a reverse drive condition and a forward drive condition. In each of the positions during a neutral to reverse, neutral to forward, or forward/reverse interchange, the shift valves are conditioned to be hydraulically on thereby permitting the manual control valve to be the controlling valve member for completing the interchange.

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 a multi-speed transmission has a multiple gain trim valve that controls the engagement pressure rise in a selectively engageable torque transmitting mechanism. The trim valve has a valve spool and a plug valve longitudinally aligned in a valve bore such that four separate areas are present. One of the areas has the engagement pressure of the torque transmitting mechanism imposed thereon. Another of the areas has a control pressure imposed thereon and the remaining two areas are subjected to the trim pressure. The gain rate between the trim pressure and the engagement pressure determines the rapidity with which the torque transmitting mechanism is engaged. The control pressure reduces the effect of the trim pressure to provide a low gain rate until the product of the trim pressure and one of the areas is equal to or greater than the product of the control pressure and the area on which it operates.

Abstract: A powertrain has a multi-speed transmission with an electro-hydraulic control system for establishing the operating conditions of the transmission. The control system has a plurality of shift or relay valves that are each alternatively positioned by a spring or a solenoid controlled pressure bias. One of the relay valves, which controls two friction devices, has a latching mechanism which will retain the valve in the pressure set condition until the pressure in one of the friction devices is decreased below a predetermined pressure. The latch mechanism will also serve to retain the transmission in a low forward ratio if an electrical discontinuance should occur when the transmission is conditioned for the low forward ratio. The control will also permit retention in the highest forward ratio if electrical discontinuance occurs during operation in this ratio. Following an engine shutdown and restart, the transmission can be selectively operated in a reverse ratio, a neutral condition or the third forward ratio.

Abstract: A pressure control valve system for a friction device has a regulator valve with a plurality of pressure feedback differential areas which are selectively pressurized during the engagement of a friction device to control the apply pressure at one rate during normal operation and at a higher rate during high torque demand operation. A plug valve is disposed adjacent the regulator valve to establish two variable control forces acting on the regulator valve in response to a variable control pressure. The combination of the differential areas and the plug valve permit the regulator valve to establish two distinct pressure gain functions, each of which has a knee or inflection point resulting in two pressure gain ratios.

Abstract: A power transmission control selectively establishes five forward speeds and one reverse speed by the controlling of three relay valves and two variable pressure TRIM valves. The TRIM valves normally control the pressure in the on-coming and off-going friction devices, respectively. The TRIM valves switch functions between ranges. In the fifth speed, the relay valves provide a pathway or passage for directing the fluid output of one of the TRIM valves to a control area on a system regulator valve to effect a variable main pressure.

Abstract: A rotating clutch has a feed passage that is maintained at a predetermined pressure by a backfill control valve during periods of clutch disengagement when the clutch apply chamber is not pressurized. The valve is slidably disposed in a stationary housing in fluid communication between a pressure source and the apply chamber of the clutch. When the pressure source is reduced below a predetermined level, the valve is positioned to prevent the pressure in the passage from decreasing below the predetermined level while exhausting the clutch apply chamber. When clutch actuation is desired, the pressure source increases to open the backfill valve. With the valve opened by pressure, the fluid pressure is supplied to the clutch apply chamber thereby applying the clutch. The valve is positioned in the housing to admit pressurized fluid from the source to the clutch apply chamber while disconnecting the apply chamber from exhaust when clutch apply is required.

Abstract: An electro-hydraulic transmission control has a plurality of shift valves or relay valves controlling the selective delivery of pressure fluid to friction devices and for exhausting pressure from the friction devices. One of the shift valves is operable in reverse and low drive range to prevent engagement of a torque converter clutch and is also operable to permit engagement of the torque converter clutch in neutral and in low hold range.

Abstract: A hydraulic control for a transmission has a main line regulator, a torque converter clutch relay valve and a torque converter clutch solenoid valve. During torque converter operation, the pressure regulator is subjected to a line pressure bias signal and supplies pressurized hydraulic fluid to a control system at a substantially constant pressure level. During torque converter clutch operation, the pressure regulator is subjected to an additional line pressure bias signal and a variable pressure bias signal from the torque converter clutch solenoid valve to provide a modulated pressure control whereby main pressure is varied proportionally with torque converter clutch apply pressure.

Abstract: Power transmissions incorporate gear ratios including a plurality of forward ratios, a neutral condition and at least one reverse ratio. The establishment of each ratio is controlled by selectively engageable hydraulically operated friction devices, such as clutches and brakes. The interchange between forward ratios is controlled by the interchange of at least one friction device. The control elements to accomplish the establishment and interchange of the ratios include a pressure source, shift valve, solenoid control valves and pressure control valves. The solenoid valves are electrically actuated and the hydraulic portion of the control includes elements that permit continued operation of the transmission in selected ratios in the event of electrical discontinuance.