Ford Global Technolgoies, LLC

Cory Benson LaRoche

Stephen Michael Cicala

Kendrick Morrison

Bradley Dean Riedle

Jianping Zhang

Derek Kinch

Kurt Howard Nickerson

Brian Michael O'Neil

Philip Joseph Wiethe

John Randall Armstead

Jaewon Choi

Kenneth Edward Sovel

Pramod Kumar Jain

Alexander Phillip McDonnell

Markian Oleh Diakiw

Joseph Scott Slayton

Jeremy L Russell

Brad Warren Probert

Benjamin Rupley

Mehran Namazkar

Ravindra Velamakanni

Leonidas Kiliaris

Spencer Johnson

According to one embodiment, a vehicle includes a transmission, a brake pedal, and a controller. The controller is programmed to, in response to an upshift of the transmission, a driver-demanded torque being zero, and the brake pedal being released, command a first pressure, that is greater than zero, to an oncoming shift element associated with the upshift such that the oncoming shift element has a torque capacity of zero, in response to the brake pedal being applied during the upshift of the transmission, command a second, larger pressure to the oncoming shift element to increase the torque capacity to a non-zero value, and, in response to expiration of a threshold time from the brake pedal being applied, command a series of sequentially ramping pressures to the oncoming shift element to further increase the torque capacity and lock the oncoming shift element.

Transition control for low torque upshifts of an automatic transmission

In a transmission hydraulic control system, a gain control valve may be used to switch between a low gain and a high gain based on line pressure. Line pressure may be controlled as a function of turbine torque. If the gain of a holding element or oncoming element changes during a shift as a result of changing turbine torque, shift quality may degrade. If the gain is set low at the beginning of the shift, the controller limits engine torque to ensure that the line pressure is not increased beyond a level that would cause a gain switch. If the gain is set high at the beginning of a shift, the controller maintains the line pressure high enough to prevent a switch to low gain, even if turbine torque drops.

Transmission control to avoid gain switch during shift

A controller commands an engine torque level in response to a driver demanded torque based on an accelerator pedal position. If the driver demanded torque decreases rapidly during or just prior to a torque phase of a shift, the controller commands the engine to temporarily generate torque exceeding the driver demand. The controller sets a nominal engine torque equal to the driver demand torque before the rapid decrease, slowly decreases the nominal engine torque during the torque phase, and decreases the nominal torque at progressively faster rates during the inertia phase to bring the nominal torque back into agreement with the driver demanded torque. The commanded engine torque is based on the nominal torque, but may be less than the nominal torque during the inertia phase to permit the engine speed to decrease faster.

Input torque control during transmission shift

In order to pre-stage a clutch piston in preparation for clutch engagement, a controller commands a high current to a Casting Integrated Direct Acting Solenoid (CIDAS) valve. This staging is performed in two distinct phases wherein the current is higher in the first phase than in the second phase. Staging the piston in this manner reduces the staging time and reduces the variability of the staging time. The duration of the first phase may be adjusted based on a number of parameters including, the length of a preceding engine off period, the number of clutch applications since the engine off period, a fluid temperature, and a length of time since a preceding engagement of the clutch.

Two-phase transmission clutch staging

A vehicle includes a transmission and a controller. The transmission has clutches and multiple speed ratios that are established during gear upshifts upon torque being transferred from off-going to oncoming clutches. The controller is programmed to, in response to a difference between actual and target times of a desired flare at a transmission input exceeding a threshold during an upshift, adjust the torque of the off-going clutch during a torque transfer phase of a subsequent upshift based on the difference.

Adaption of off-going clutch torque

A vehicle powertrain includes an engine and a transmission, each controlled by controllers that communicate with one another. When the vehicle is coasting in certain gears, a one-way clutch over-runs. When the driver depresses the accelerator pedal (tips in), the transmission controller adjusts a transmission torque demand limit which is communicated to the engine controller. In response, the engine controller adjusts the engine torque, resulting in a smooth re-engagement of the one-way clutch.

Vehicle control during tip-in

A vehicle includes an accelerator pedal moveable across a plurality of predefined positions and a controller programmed to, responsive to the pedal reaching a tip-in position, command a downshift to a downshift gear from an initial gear. A difference between the initial and downshift gears exceeds a number of predefined positions crossed upon moving to the tip-in position when a rate of change of pedal position exceeds a predefined threshold.

Downshift scheduling for a vehicle

During the inertia phase of a shift, the oncoming clutch is controlled to alleviate shift quality degradation due variability of clutch friction coefficient. The friction coefficient sometimes increases as the slip speed nears zero. The commanded clutch pressure is a sum of an open loop term and a closed loop term. The open loop term decreases as the clutch slip decreases. Thus, when the friction coefficient increases at the end of the inertia phase, the clutch torque remains nearly constant. When the friction coefficient does not increase at the end of the inertia phase, the closed loop term responds to the resulting decreasing rate of slip speed reduction.

Method of controlling a transmission clutch

A transmission includes a latch valve with latched and de-latched states. In the de-latched state, the latch valve directs a control pressure to a clutch apply circuit. In the latched state, which is entered in response to a control pressure higher than a latch pressure, the latch valve directs a line pressure to the clutch apply circuit. A controller manages the transition from latched to de-latched differently depending upon the transmission input torque and gear state. At high transmission input torque, the controller first reduces the control pressure to rapidly accelerate a spool in the latch valve, and then increases the control pressure to prevent clutch slip. At low torque, the controller reduced the pressure to an intermediate value during the transition and then reduces it again. At moderate torques, the controller reduces the pressure directly to a target pressure in a single step.

Control of transmission latch valve

A method for controlling gearshifts of an automatic transmission includes preventing an upshift while the vehicle accelerates on an ascending grade, if predicted vehicle acceleration in a target gear is less than a reference vehicle acceleration in the target gear; accelerating the vehicle on the grade; and producing the upshift, if predicted vehicle acceleration in the target gear is greater than a reference vehicle acceleration.

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Wixom, MI, United States of America

Cory Benson LaRoche