A clutch includes a clutch disk that rotates by receiving motive power from an engine and a clutch plate switched between an engaged state in which it is engaged with the clutch disk and a disengaged state in which it is not engaged with the clutch disk. A controller calculates a coefficient of friction μ between the clutch disk and the clutch plate based on a time period Δt elapsed from a first time point when the number of relative rotations of the clutch disk and the clutch plate attains to a first number of rotations to a second time point when a second number of rotations smaller than the first number of rotations is attained, in a state in which the clutch disk rotates while transfer of motive power from the engine to the clutch disk is cut off and in the engaged state.

Methods and systems are provided for controlling and diagnosing one or more clutches in a transmission. In one example, a method for operation of a vehicle system is provided that includes at a diagnostic controller or processing unit independent from a driveline controller or processing unit, respectively, determining an engagement state of a clutch in a transmission of the vehicle system, wherein the engagement state is selected from a group of three or more clutch engagement states. The method further includes identifying an unauthorized clutch state based on the engagement state of the clutch and a speed of the vehicle and responsive to the identification of the unauthorized clutch state, operating the vehicle system in a fault state.

A transmission for a vehicle having a prime mover with an output shaft. The transmission includes an offgoing clutch that is selectively connected to the output shaft, and a controller in communication with the prime mover. The controller includes an offgoing clutch control module that determines an offgoing clutch torque profile at the start of a torque phase in a power downshift that does not exceed a predetermined offgoing clutch energy threshold and a torque request module that limits a rate of input torque into the transmission from the prime mover based upon the determined offgoing clutch torque profile.

A method is provided for calibrating a control algorithin of a clutch control unit of a vehicle. The method includes requesting, clutch disengagement, or engagement, monitoring clutch actuator position, determining a time interval that starts with the clutch disengagement or engagement request and ends when the clutch actuator has reached a predetermined position, and calibrating an estimated time interval of the control algorithm starting with clutch disengagement or engagement bequest and when the clutch actuator has reached a predetermined position based on the determined time interval. A computer program for implementing the method, as well as a vehicle comprising a clutch control unit calibrated according to the method, are also provided.

A system for a vehicle includes a desired pressure module, a valve actuation module, a filter module, and a capacity detection module. The desired pressure module selectively generates an increase in a desired pressure of hydraulic fluid for a clutch of an automatic transmission. The valve actuation module actuates a solenoid valve based on the desired pressure. The solenoid valve supplies hydraulic fluid to a regulator valve, and the regulator valve supplies hydraulic fluid to the clutch. The filter module filters an acceleration of a shaft of the automatic transmission to generate a filtered acceleration. The capacity detection module indicates whether the clutch reached torque carrying capacity based on the filtered acceleration.

At the time when a hydraulic actuator is operated to engage a dog clutch, after it is detected that a hydraulic pressure for operating the hydraulic actuator is higher than or equal to a predetermined hydraulic pressure, it is determined whether the dog clutch is not engaged. Therefore, non-engagement determination due to insufficient hydraulic pressure for operating the hydraulic actuator is prevented. Thus, at the time when the hydraulic actuator is operated to engage the dog clutch, it is possible to prevent consumption of time to engage the dog clutch due to unnecessary re-engagement operation.

A shift control method for a DCT vehicle, which adjusts a time required to shift gears through clutch control in a DCT. The shift control method includes controlling a release-side dutch such that the release-side dutch is partially disengaged by a controller when gear shifting is initiated in a state in which an accelerator pedal is not pressed, performing synchronization control by partially applying an apply-side dutch torque in an initial stage of synchronization such that an engine rotational speed follows and synchronizes an apply-side input shaft speed, and partially applying a release-side dutch torque in a last stage of synchronization by the controller, and performing torque hand-over control such that an apply-side clutch is engaged while the release-side clutch is disengaged by the controller, after performing the synchronization control.

A transmission includes a first hydraulic clutch, a second hydraulic clutch, a third hydraulic clutch, a pump and a controller. The first, second, and third hydraulic clutches are configured to established a parked-ready condition upon engagement of all three clutches. The pump is configured to generate hydraulic fluid pressure. The controller is programmed to, in response to a command to start an engine that powers the pump, engage the first and second clutches. The controller is further programmed to, in response to engagement of the first and second clutches and obtaining operating hydraulic fluid pressure, engage the third clutch.

A vehicle control system for improving vibration suppressing performance and acceleration response is provided. A controller is configured to set the torque transmitting capacity of an engagement device to a first torque transmitting capacity that is smaller than a value required to transmit a peak value of a second drive torque applied to an output shaft of a transmission having the engagement device but greater than a value required to transmit an estimated first drive torque generated by an engine, when the second drive torque is amplified by pulsation of the first drive torque.

A method for controlling a manual transmission includes using a controller to determine a desired torque transmitted through an input clutch for the desired gear after a shift lever is moved to a desired gear position and while a clutch pedal is being released for engaging the clutch; inferring torque in the vehicle drive assembly; using inferred torque to determine clutch torque; and using the controller to automatically adjust a clutch actuator such that a difference between the desired torque and the inferred torque is reduced.