Gm Global Technolgoy Operations, Inc.

Craig J Hawkins

Matthew D Whitton

Christopher Jay Weingartz

Steven Patrick Moorman

Xuefeng Tim Tao

Keith D Van Maanen

Crystal Nassouri

Colin Hultengren

David H Vu

Roger Joseph Rademacher

Christopher E Whitney

Paul Alan Bauerle

Paul G Otanez

Bret M Olson

Andrew W Baur

Brian M Porto

Adam J Heisel

Chinar S Ghike

Michael J Pitsch

Mark A Schang

Robert L Williams

Jonathan P Kish

Brian James Pellerito

Roberto Diaz

Jayson S Schwalm

Herve Scelers

Jeryl McIver

Matthew Kempeinen

Brandon M Fell

Alexander S Barath

James L Abington

Cheol W Kim

Pratap Atchutha Naick

Michael Chernyak

Minh Q Truong

Hiep T Do

Timothy J Keenan

Emmanuel V Yabes

Ruobai Zhang

Paul R Peterson

Mark A Yacoub

A continuously variable transmission (CVT) for a vehicle includes an input member, an output member and a variator assembly including a first pulley rotatably coupled to the input member and a second pulley rotatably coupled to the output. The first and second pulleys are rotatably coupled by a flexible continuous rotatable device. A control system is provided including an instruction set executable to determine an initial variator speed ratio of the variator assembly and detect an event causing a change in an operational state of the vehicle. The control system determines a compensation strategy to adjust the variator speed ratio in response to the change in the operational state of the vehicle and generates an adjusted variator speed ratio based upon the compensation strategy. The control system transmits the adjusted variator speed ratio to the variator assembly.

System and method for controlling a continuously variable transmission

A powertrain system including an internal combustion engine rotatably coupled to a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining minimum and maximum CVT input speeds in response to an accelerator pedal position, and monitoring vehicle speed and a CVT input speed. A target CVT input acceleration rate is determined based upon the vehicle speed, and a desired speed ratio is determined that is responsive to the target CVT input acceleration rate. The CVT is controlled based upon the desired speed ratio.

Method and apparatus to control a continuously variable transmission

A target module determines a target ratio between a speed of an input shaft and a speed of an output shaft of a continuously variable transmission (CVT) based on an accelerator pedal position. A maximum rate of change (ROC) module determines a maximum ROC of the target ratio. A switching valve control module, based on a comparison of the maximum ROC and a ROC of the target ratio, selectively actuates a switching valve of the CVT one of (i) from a closed position to an open position and (ii) from the open position to the closed position. The switching valve prevents transmission fluid flow through a flow path between a transmission fluid pump and a pressure regulator valve of the CVT when the switching valve is in the closed position. The switching valve allows transmission fluid flow through the flow path when the switching valve is in the open position.

Pump switching control systems and methods for continuously variable transmissions

A method for learning the bite point of a position-controlled clutch in a vehicle having an engine and a transmission includes commanding an engagement of a clutch fork via a controller when the transmission is in park and the engine is idling. The method also includes controlling an apply position of the clutch via the controller, calculating a clutch torque capacity of the clutch, and measuring the apply position via a position sensor. The apply position is recorded as the clutch bite point when the calculated clutch torque capacity equals a calibrated clutch torque capacity. The transmission is then controlled using the recorded clutch bite point. A system includes the transmission, input clutches, and a controller configured to execute the method. A vehicle includes an engine, the transmission, the position-controlled input clutch, and the controller, as well as a clutch position sensor.

Transmission system with clutch bite point learning logic

A method of controlling a clutch-to-clutch power-on upshift of a transmission includes defining a possible engine torque as a latched possible engine torque value. An on-coming clutch torque phase target value is defined as a latched on-coming clutch torque value, and held constant until a final ramp. A commanded engine torque is reduced and maintained to a maximum torque reduction value until a shift completion ratio is achieved. The commanded engine torque is increased until the commanded engine torque is equal to a restore ramp target value. Both the on-coming clutch torque and the commanded engine torque are simultaneously increased at a final ramp rate, such that the increase in the on-coming clutch torque parallels the increase in the commanded engine torque, until an actual engine torque is substantially equal to the possible engine torque, to complete the shift.

Method of controlling a vehicle during a clutch-to-clutch power upshift of a transmission

A method of controlling a downhill rolling shift sequence (DRSS) of a vehicle having an engine and a dual-clutch transmission (DCT) includes initiating a DRSS upon detecting a rolling downhill condition of the vehicle in an initial gear state, identifying an exit gear state corresponding to the initial gear state, shifting the DCT to a rolling neutral state when a speed of an initial gear input shaft is equal to an idle speed of the engine, initiating synchronization of the engine speed with the speed of an exit gear input shaft when the shaft speed is equal to the engine idle speed, and shifting the DCT from the rolling neutral state to the exit gear state when the synchronized speed of the engine and the exit gear input shaft is equal to a calibrated exit speed defined by the exit gear state. A system for controlling the DRSS is provided.

Rolling downhill shift control of a transmission

A method of controlling a transmission includes selecting a target speed of a second shaft, and measuring a second speed of the second shaft and an output speed of an output shaft. The method includes detecting a rolling neutral condition wherein a first and second clutch are uncoupled from a torque generator and a synchronizer is mated to a predicted gear to apply a load in a direction, and one of a first condition wherein the output speed is decreasing and the target speed is less than the second speed and a second condition wherein the output speed is increasing and the target speed is less than the second speed. The method then includes translating the synchronizer away from the predicted gear, coupling and decoupling the second clutch to and from the torque generator, and mating the synchronizer to the predicted gear to again apply the load in the direction.

Method of controlling a transmission

A method of executing a downshift in a fixed-gear powertrain having an input node and an output node related by a starting speed ratio before the downshift and a finishing speed ratio after is provided. The downshift includes a torque phase and an inertia phase. A starting output torque is calculated as a function of a starting driver request. An electric machine applies a starting regenerative input torque which is calculated as substantially equal to the starting output torque divided by the starting speed ratio. A finishing output torque is calculated as a function of a finishing driver request. The electric machine applies a finishing regenerative input torque which is calculated as substantially equal to the finishing output torque divided by the finishing speed ratio.

Negative-torque downshift execution for fixed-gear transmissions

A vehicle includes an engine, a dry dual-clutch transmission (dDCT) having a pair of input clutches and a gearbox containing oddly- and evenly-numbered gear sets, and a transmission control module (TCM). Application of one of input clutches connects the engine to a corresponding one of the oddly- or evenly-numbered gear sets. The TCM includes feed-forward PID-based control logic, and a torque-to-position (TTP) table for each input clutch. The TCM commands a position of a designated input clutch during a power-on upshift using the feed-forward, PID-based control logic, and selectively adapts the TTP table as a function of an inertia and acceleration value of the engine. The TCM may apply an asymmetrical handoff profile to commanded oncoming and offgoing clutch torques during the torque phase of the upshift. The TCM may also adjust the TTP table as a function of the frequency of use of the input clutches.

Upshift control of a dry dual-clutch transmission

A vehicle includes an engine having autostart functionality, a source of fluid pressure when the engine is off, a flow control solenoid that outputs a variable clutch pressure, a transmission, an electric motor, and a controller. The transmission includes a clutch in fluid communication with the solenoid. The clutch applies via the clutch pressure to establish a first gear launch state. The motor is powered via a rechargeable energy storage system. The controller executes a method to transmit pulse width modulation (PWM) control signals to the solenoid upon detection of a set of conditions triggering the autostart event to lower clutch pressure to a first calibrated level. Restart of the engine is commanded, and the clutch pressure increases toward a second calibrated level while engine speed is increasing. The controller discontinues the PWM control signals and increases clutch pressure to line pressure when the input speed exceeds a calibrated threshold.

Transmission oil pressure control during engine autostart

A system and method can control the dry dual clutch transmission (dDCT) of a vehicle. The method includes modifying a recorded torque-to-position (TTP) table based on a calculated clutch torque difference between a calculated clutch torque and a commanded clutch torque. The commanded clutch torque is provided by a transmission control module and is defined as a clutch torque sufficient to move the vehicle without applying the accelerator applier after the brake applier has been released. The calculated clutch torque is a function of the actual engine torque value, the engine inertia, and the engine acceleration.

System and method for controlling a dry dual clutch transmission of a vehicle

A vehicle includes an engine, an engine control module (ECM), and a dual clutch transmission (DCT) assembly. The DCT assembly has first and second input clutches, first and second gear sets selectively connected to the engine via the respective first and second input clutches, and a transmission control module (TCM). In executing a launch control method, the TCM receives a launch request, receives an actual engine torque, and determines the inertia and acceleration of the engine. The TCM then calculates a clutch torque for the particular input clutch used for vehicle launch as a function of the actual engine torque and the product of the inertia and the acceleration, compares the calculated clutch torque to the commanded clutch torque, modifies a torque-to-position (TTP) table depending on the comparison result, and transmits a clutch position signal to the designated input clutch to command an apply position extracted from the TTP table.

Dual clutch transmission vehicle launch control

A clutch control system for a vehicle includes a shift command module and an offgoing clutch control module. The shift command module commands an upshift of a clutch-to-clutch transmission when an engine torque is less than a predetermined negative torque. The offgoing clutch control module increases an offgoing clutch pressure above a predetermined apply pressure in response to the command. An offgoing clutch is fully engaged when the offgoing clutch pressure is greater than the predetermined apply pressure.

Negative torque upshift offgoing clutch control systems and methods

A control system for an engine includes a torque phase detection module, a torque request generation module, and an engine torque control module. The torque phase detection module detects a start of a torque phase of an upshift of a transmission coupled to the engine. The torque request generation module generates an engine torque request at the start of the torque phase of the transmission upshift. The engine torque control module controls engine torque during the torque phase of the transmission upshift based on the engine torque request.

System and method for decreasing acceleration disturbance during transmission upshifts

A method of controlling a vehicle includes signaling a transmission to shift into a first gear ratio and sensing a current gear ratio of the transmission after signaling the transmission to shift into the first gear ratio. The method further includes implementing a diagnostic transmission shift control strategy to override a normal transmission shift control strategy when the current sensed gear ratio is not equal to the requested first gear ratio to verify proper functionality of a mode control valve that is responsible for shifting the transmission into the first gear ratio.

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Howell, MI, United States of America

Craig J Hawkins