Gm Global Technolgoy Operations, Inc.

Carl A Lentz

John A Hibner

Jeffrey Kurt Runde

Joseph H Hunter

Christopher R Wiles

Charles Francis Long

James C Polak

Kenneth B Harmon

Walter Eric Palmer

Robert H Schaefer

Stephen F Spurlin

Richard J Koenig

Harry Fackenthal

Jon M Huber

Clement P Miller

The on-coming clutch of an automatic transmission is filled for a fill time determined from empirical data embodied in look-up tables which relate the effects of pump speed and fluid temperature on the fill time. The fill time is determined for a baseline clutch and then multiplied by a volume ratio for a particular clutch. The effect of fluid temperature on leakage is tabulated and used with the pump speed to determine the effective pumping speed. The effects of fluid temperature on viscosity and oil flow rate are determined and used to adjust the base fill time for low pumping speeds. The fluid retained in a clutch cavity from a recent application and not fully exhausted is also taken into account.

Compensated control method for filling a fluid-operated automatic

In an automatic transmission upshifting is controlled by ramping down the pressure in an off-going clutch associated with a high speed ratio and increasing the pressure in an on-coming clutch associated with a lower speed ratio. The on-coming clutch has commanded pressure at a maximum value for an initial fill time, a lower increasing ramp value during the ramp of the off-going clutch until the on-coming clutch starts to engage, and then a closed-loop control until the clutch reaches a synchronous speed. The closed-loop control parameter is on-coming clutch slip which is controlled to a calculated slip speed profile. Parameters for controlling the quality of a shift such as on-coming clutch initial pressure, off-going clutch initial pressure and on-coming clutch fill time are automatically adjustable during vehicle use to correct shift aberrations which degrade shift quality. A fast adjustment mode is in effect initially to calibrate the transmission control for the engine and vehicle. After a smooth shift is obtained only small adjustments are allowed.

Adaptive control of an automatic transmission

In an automatic transmission, clutch-to-clutch powered downshifting is controlled by filling the on-coming clutch at a low pressure while ramping down the off-going clutch pressure until turbine speed is pulled up due to off-going clutch slippage, and then increasing the off-going pressure stepwise to compensate the change from static to dynamic coefficients of friction. Then the on-coming pressure is gradually ramped up and a closed-loop profile control period starts wherein the slip speed of the on-coming clutch is measured and controlled to a slip speed profile by controlling the off-going clutch pressure. When synchronization of the on-coming clutch is first detected, a closed-loop sync control period starts wherein the off-going pressure is controlled to minimize the slip and the on-coming pressure is ramped up at a steeper rate to begin clutch engagement during the sync control period. Adaptive control is accomplished for the initial on-coming pressure by an iterative process which decreases that pressure stepwise until flare occurs and then increases the pressure to stop the flare and repeating the changes in smaller steps to approach the flare condition. Initial off-going pressure is modified when early slip or late slip of the off-going pressure is detected. A modification of off-going pressure step value is effected when the final pressure in the closed-loop period is greater or smaller than the initial pressure. The modifications are targeted to fully correct the respective conditions.

Adaptive powered downshift control of an automatic transmission

The present invention provides a hydraulic control system for the automatic transmission of a vehicle. The control system utilizes only one pulse width modulating valve to provide modulated pressure to whichever of the torque transfer devices--in the nature of clutches and brakes--constitutes the single, on-coming torque transfer device required to effect the drive ratio selected in accordance with electrical control signals from an on-board, pre-programmed computer. The control system accomplishes its objective by cascading a plurality of relay valves which are coupled to preferably latching, solenoid valves (A through E) which are also controlled by computer. A control valve is interposed between the single, pulse width modulating valve and the plurality of cascaded relay valves to provide both modulated pressure (P.sub.3) and main line pressure (P.sub.1) to the various torque transfer devices of the transmission. The computer controls the solenoid valves (A through E) to determine which of the torque transmitting devices shall receive line pressure (P.sub.1) and which shall receive modulated pressure (P.sub.3). In this regard it is noted that the on-going torque transfer device is always actuated by modulated pressure (P.sub.3). Moreover, the control system is adapted for operation with vehicular transmissions that provide one more forward drive ratio than the number of torque transfer devices in the transmission.

Hydraulic control system for vehicular automatic transmission

In an automatic transmission, upshifting is controlled by ramping down the pressure in an off-going clutch associated with a high speed ratio and increasing the pressure in an on-coming clutch associated with a lower speed ratio. The on-coming clutch has commanded pressure at a maximum value for an initial fill time, a lower increasing ramp value during the ramp of the off-going clutch until the on-coming clutch starts to engage, and then a closed-loop control until the clutch reaches a synchronous speed. The closed-loop control parameter is on-coming clutch slip speed which is controlled to a calculated slip speed profile. The profile has a first steep slope and a final less steep slope so that the actual slip can smoothly go to zero in a given time period.

Clutch-to-clutch control in an automatic transmission

Garage shifts are accomplished at shifts from neutral to forward or reverse or between forward and reverse. An off-going clutch is released at the beginning of the shift for shifts between forward and reverse; shifts from neutral have no off-going clutch. The on-coming clutch has a fill time at maximum pressure, a lower increasing pressure ramp to begin engagement as indicated by pullup or pulldown, and a closed-loop control triggered by pullup or pulldown. The closed-loop control commands the pressure to control the turbine speed to a calculated profile to bring the speed to a target value. When the target value is attained the closed-loop control is terminated and maximum pressure is applied. For low speed shifts and for a high speed shift between forward and reverse, the target value is zero. For high speed shifts from neutral the target value may be either above or below the initial turbine speed.

Control method for automatic transmission garage shifts

In an automatic transmission, clutch-to-clutch closed throttle downshifting is controlled by filling the on-coming clutch at a maximum pressure command for a set period while commanding the off-going clutch pressure to a low value and exhausting the off-going clutch before the end of the fill period. At the end of the fill period the on-coming pressure is set to an initial value and then ramped up until turbine speed is pulled up due to off-going clutch slippage. Then a closed-loop profile control period starts wherein the slip of the on-coming clutch is measured and controlled to a slip profile. When synchronization of the on-coming clutch is detected, maximum pressure is commanded. If the throttle is opened during the downshift, the algorithm reverts to a powered downshift algorithm if the off-going clutch still has pressure or to an open-loop ramp control of the on-coming clutch if the off-going clutch has been exhausted.

Method of clutch-to-clutch closed throttle downshift in an automatic

The disengagement of the off-going clutch is monitored to determine as early as possible if there is a clutch tie-up due to failure to disengage. Beginning at the initial clutch release command, the turbine speed and output speed are used to determine if clutch slip has occurred and a pass signal is given if slip occurs in several consecutive control loops. Beginning a preset time after the command to fully exhaust the clutch, the number of no-slip conditions are counted. A fail signal is given when a set number of no-slip conditions are counted.

Method of detecting clutch tie-up during transmission shifting

In an automatic transmission, clutch-to-clutch powered downshifting is controlled by filling the on-coming clutch at a low pressure while ramping down the off-going clutch pressure until turbine speed is pulled up due to off-going clutch slippage, and then increasing the off-going pressure stepwise to compensate the change from static to dynamic coefficients of friction. Then the on-coming pressure is gradually ramped up and a closed-loop profile control period starts wherein the slip of the on-coming clutch is measured and controlled to a slip profile by controlling the off-going clutch pressure. When synchronization of the on-coming clutch is first detected, a closed-loop sync control period starts wherein the off-going pressure is controlled to minimize the slip and the on-coming pressure is ramped up at a steeper rate to begin clutch engagement during the sync control period.

Control method of clutch-to-clutch powered downshift in an automatic

A brake unit having a hydrodynamic retarder providing brake torque proportional to speed and inlet pressure, and a friction brake providing brake torque proportional to net brake pressure, the brake apply pressure minus retarder inlet pressure. The controls have a brake demand valve providing a brake demand pressure. A retarder valve is biased by brake demand pressure from brake-off position to brake-on position for switching the retarder circuit to fill the retarder and to connect low and high speed regulator valves to regulate retarder inlet pressure respectively to increase in the low speed range and to decrease in the high speed range with increasing speed, and to limit retarder inlet pressure proportionally to brake demand. The controls, in the low speed range, provide friction brake apply pressure proportional to brake demand, so the friction brake net apply pressure and torque decrease to zero and retarder torque increases as speed increases. In the high speed range, retarder torque decreases with increasing speed. Total brake power increases in an approximately straight line relation to speed.

Power limiting control for retarder with friction brake

A retarder and friction brake system having vehicle service brakes and a shaft brake unit having a hydrodynamic retarder and friction brake. Manual brake controls provide for initial brake apply of the brake unit and then apply of the service brakes or independent apply of the service brakes. The brake unit has a dual chamber, hydrodynamic retarder with opposed bladed stators and a central rotor member having opposed bladed rotors mounted between the stator members for limited axial movement and rotation with a drum fixed to the shaft, and a friction brake having plates located concentrically within the retarder chambers on opposite sides of the rotor and splined to the drum and stators and a brake apply motor. In response to brake demand, the brake controls provide air pressure proportional to brake demand to the brake apply motor and fluid pressure proportional to brake demand and, in a low speed range limited to lower values with decreasing speed, to a brake chamber to provide a release pressure on the brake apply motor and flow through the constant restriction cooling passages in the brake plates to the retarder chambers for retarder braking and pumping through a cooler to provide with increasing speed in the low speed range, decreasing friction braking and increasing retarder braking having a total value proportional to brake demand, and in the higher speed range low friction braking and high retarder braking having a total value proportional to brake demand and increasing in a substantially straight line with increasing speed.

Retarder and friction brakes

A multiratio powershift transmission with a shift control system having a manually selected roading phase and a working phase. The roading phase for vehicle drive permits manual selection of a normal automatic shift control mode providing automatic shifting between ratio drives in response to output speed and throttle for maintaining the engine driven input in a normal speed range for optimum economy at part throttle and optimum performance at full throttle, and a hold automatic shift control mode providing a manually selected ratio drive with hold automatic upshifts and normal automatic downshifts and inhibiting manual hold downshifts between ratio drives in response to output speed to limit engine driven input speed to a maximum speed range during overrun drive. The working phase for driving a works, such as a derrick, permits manual selection of the ratio drives to provide progressive output speed control in response to throttle, and provides hold upshifts and inhibited manual downshifts to limit engine speed to a maximum speed range.

Transmission with automatic and manual control modes

A multiratio powershift transmission having automatic shift valves normally operative in response to output speed governor pressure and throttle pressure to automatically upshift the transmission to higher ratios with increasing speed with the upshift at higher speeds with increasing throttle. A back-up governor pressure system having an input governor pressure regulated by a pressure regulator valve to provide a reduced modified governor pressure in first ratio and operative in response to progressively higher ratio signals to progressively increase the reduced pressure to provide a modified input governor pressure varying with output speed similar to output governor pressure which is used instead of output speed governor pressure to provide a similar shift schedule relative to output speed.

Range shift control by input governor

A transmission having a fluid operated forward and reverse drive gear unit and a three speed gear unit to provide three forward and three reverse speed drives. A one-two relay valve in downshift position provides first speed drive and on upshift functions with a downshifted two-three relay valve to provide second speed drive. The two-three relay valve on upshifts provides third speed drive. The one-two relay valve is upshifted in response to either forward or reverse second pressure and the two-three relay valve will upshift in reponse to either forward or reverse third pressure. Each relay valve will downshift in the absence of such pressure except when output speed is above a predetermined value. A manual selector valve is operative in first, second or third forward drive positions to provide first forward pressure to engage forward drive in all forward positions, second forward pressure in second and third forward positions and third forward pressure in third forward position and similarly operative in first, second or third reverse drive positions to provide first reverse pressure to engage reverse drive in all reverse positions, second reverse pressure in second and third reverse position and third reverse pressure in third reverse position. The second forward or reverse pressure is connected to upshift the one-two relay valve. The third forward or reverse pressure is connected to upshift the two-three relay valve. This system provides manual selection of first, second or third speed in either forward or reverse drive and inhibits downshifts above a predetermined speed.

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Mooresville, IN, United States of America

Carl A Lentz