Aspects of the present invention relate to a method of using a transmission with multiple clutches in order to provide improved methods of traction control on a hill ascent. Embodiments provide for the use of power-shift, automatic or dual clutch gearboxes.

CVT controller has rotation speed sensors detecting driving and driven wheel rotation speed; driving and driven wheel speed difference detection unit detecting wheel speed difference vfr; and bad road judgment unit judging that road is bad road when vfr is first value vfr_br or greater. CVT controller further has first belt clamping force increase unit increasing belt clamping force in case where road is judged to be bad road, as compared with case where road is not judged to be bad road; vibration detection unit detecting vehicle speed vibration fvsp; and second belt clamping force increase unit increasing belt clamping force when vfr is second value vfr_psec or greater or when fvsp is third value fvsp_psec or greater in case where road is not judged to be bad road, as compared with case where vfr is less than vfr_psec and case where fvsp is less than fvsp_psec.

A continuously variable transmission, a transmission control system, and a method is provided. The control system is configured to determine whether a predetermined condition is met for applying a clutch critical pressure to an applied clutch. The clutch critical pressure is less than line pressure and is a pressure at which the clutch may slip upon experiencing a predetermined torque disturbance level. The control system is configured to command the clutch critical pressure to be applied to the clutch if the predetermined condition is met. The control system is further configured to determine whether the clutch is slipping beyond a predetermined threshold, and if the clutch is slipping beyond the predetermined threshold, command a clutch slip control scheme to be applied to the clutch that is configured to bring a clutch slip of the clutch under the predetermined threshold.

A method for controlling the traction of a vehicle hydraulic assistance circuit, including a target pressure is applied, a setpoint pressure and a theoretical value of a parameter are determined, a pressure setpoint is applied to the hydraulic pump, equal to the setpoint pressure, and an actual value is measured in the hydraulic assistance circuit. The actual value measured in the hydraulic assistance circuit is compared to the theoretical value, and if a gap between the actual value and the theoretical value is greater than a threshold value, a step of adjusting the setpoint is carried out in which the pressure setpoint of the hydraulic pump is modified so that it is equal to an actual pressure, to within an adjustment coefficient.

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.

A system and method for controlling a vehicle having a continuously variable transmission (CVT) comprises a control system having at least one controller, an accelerometer and one or more sensors in communication with the at least one controller to monitor and detect a change in an operational state of the vehicle. The control system determines a vehicle acceleration rate with the accelerometer in response to the change in the operational state of the vehicle. An adjusted vehicle speed is computed based, at least in part, on the vehicle acceleration rate. A variator speed ratio is generated based upon the adjusted vehicle speed and transmitted to the variator assembly of the CVT.

An electronic control unit is configured to, when the electronic control unit determines that any one of a first condition and a second condition is satisfied, preferentially execute lower limit speed ratio control. The first condition is a condition that, after the electronic control unit starts shift prohibition control, a wheel lock has occurred before a condition for cancelling the shift prohibition control is satisfied. The second condition is a condition that, after the electronic control unit starts the lower limit speed ratio control, a wheel spin has occurred before a condition for cancelling the lower limit speed ratio control is satisfied.

Embodiments of the present invention provide a system comprising: a first controller configured in each of a predetermined plurality of states to generate a torque request signal in order to cause a vehicle to operate in accordance with a target speed value, the system being configured, when the first controller is one of said plurality of states to generate a gear shift limit signal to cause a change in an engine speed at which a transmission controller is permitted to cause a gear downshift, the gear shift limit signal being generated in dependence on at least one traction indicator signal indicative of an amount of estimated traction between the vehicle and a driving surface.

A transmission system for vehicle includes a clutch disposed in a power transmission path between an engine and a vehicle wheel, a transmission disposed in the power transmission path, a clutch actuator, a shift actuator, a vehicle wheel speed sensor, a sudden deceleration detecting unit that detects a sudden deceleration of the vehicle wheel based on an output signal of the vehicle wheel speed sensor, and a shift control unit. The shift control unit executes an ordinary shift control to shift to a speed adaptive shift stage associated with the rotational speed and to execute, when the sudden deceleration detecting unit detects the sudden deceleration of the vehicle wheel, a sudden deceleration adaptive shift control to shift to a shift stage lower than an actual shift stage at the point of detection of the sudden deceleration and higher than the speed adaptive shift stage associated with the rotational speed.

A method is proposed to complete a power-on upshift while a vehicle encounters wheel slip conditions such as driving in loose sand. The wheels slip conditions may be detected based on a maximum rate of change of an output shaft exceeding a threshold. In response to the wheel slip conditions, one or more shift parameters may be adjusted to bias the shift toward a tie-up and decrease the chance of a flare. These modified shift parameters may include an increased stroke pressure, a delayed off-going clutch release timing, and an increased ratio change capacity.