Operating a clutch assembly of a vehicle drive train, the clutch assembly comprising a clutch with a clutch component that exchanges heat at least indirectly with a medium which is conducted at least partially in the clutch, comprises at least: a) determining an operating point parameter which is representative of a current operating state of the clutch; b) determining a first thermal property parameter of the medium, as a function of the determined operating point parameter; c) determining a second thermal property parameter of the at least one clutch component; d) calculating a component temperature of the at least one clutch component as a function of at least the following three values: a further component temperature of a further clutch component, the first thermal property parameter, and the second thermal property parameter; and e) adapting activation of the clutch as a function of the calculated component temperature.

Methods and systems for operating a dog clutch actuator are disclosed. In one example, the voltage that is supplied to a dog clutch actuator is gradually reduced when a dog clutch is returned to a base position via a return spring. The voltage may be reduced at a rate that is based on a temperature of a fluid in which a dog clutch may be submerged.

A vehicle includes an engine, a transmission, and a controller. The transmission has clutches, a circuit configured to transport fluid to the clutches, a pump configured to circulate the fluid through the circuit, and an accumulator disposed along the circuit. The controller is programmed to, responsive to an engine start and a fluid temperature being less than a temperature threshold, discharge the accumulator to prime the pump.

A driving-force transmitting apparatus includes first and second friction clutches, a piston that presses the first and second friction clutches, a hydraulic pump that feeds hydraulic oil to a cylinder chamber in the piston, an electric motor that drives the hydraulic pump, and a control apparatus that controls the electric motor to adjust the discharge pressure of the hydraulic pump. The control apparatus has a feedback control apparatus that controls the electric motor using a correction value based on a deviation between a target value and an actual value of the discharge pressure of the hydraulic pump, a hydraulic-oil temperature estimating apparatus that estimates a temperature of hydraulic oil, and a gain adjusting apparatus that changes a correction amount for feedback control in accordance with the estimated temperature of the hydraulic oil.

Methods and systems for operating a dog clutch actuator are disclosed. In one example, the voltage that is supplied to a dog clutch actuator is gradually reduced when a dog clutch is returned to a base position via a return spring. The voltage may be reduced at a rate that is based on a temperature of a fluid in which a dog clutch may be submerged.

A clutch control method, including: determining whether a current vehicle state satisfies a condition for a clutch to enter a sliding friction state; if so, controlling the clutch to enter the sliding friction state, and determining a target sliding friction rotating speed of the clutch; determining whether the current vehicle state satisfies a condition for entering a clutch torque deviation collecting state; if so, collecting a torque deviation once and storing the torque deviation; at an end of an adjustment period, accumulating all torque deviations collected previously and taking an average value according to an accumulation number of times, so as to obtain an average torque deviation; if the average torque deviation exceeds a preset deviation threshold, recording the average torque deviation; and if the current vehicle state satisfies a condition for entering a deviation applying state, adjusting a current clutch friction coefficient according to the recorded average torque deviation.

A control device of an automatic transmission controls an automatic transmission 1 comprising a transmission mechanism 3 including a plurality of engagement elements, and a hydraulic oil supply device 4 supplying hydraulic oil to the transmission mechanism The control device of the automatic transmission comprises an engagement element control part 41 configured to use the hydraulic oil supply device to make the plurality of engagement elements change between an engaged state and a disengaged state; and a deceleration degree calculating part 42 configured to calculate a target deceleration degree of a vehicle in which the automatic transmission is provided. The engagement element control part is configured to make the engagement element in the disengaged state engage so that the vehicle decelerates if the target deceleration degree is equal to or more than a predetermined value when an increase in temperature of hydraulic oil in the automatic transmission is demanded.

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.

A hydrodynamic clutch having an input side and an output side, the rotational motions of which are coupled to one another with a hydraulic fluid. A method for determining the degree of filling of the hydrodynamic clutch with fluid including steps of periodically sensing a fluid temperature of the hydraulic fluid, determining the thermal output supplied to the clutch on the basis of the temperature, determining a lambda value on the basis of the thermal output and determining the degree of filling on the basis of the lambda value.

A vehicle includes a drive source, driving wheels driven by a driving force output from the drive source, a clutch disposed between the drive source and the driving wheels, the clutch being switchable to an arbitrary fastening position between a connection state that enables transmission of the driving force between the drive source and the driving wheels and a disconnection state that disconnects the transmission; a clutch actuator that applies a fastening load to the clutch and provides a torque transmission capacity corresponding to the fastening load to the clutch; and a controller that controls operation of the drive source and operation of the clutch actuator. The controller includes a clutch temperature estimation circuit that estimates the temperature of the clutch, and a driving force adjustment circuit that performs driving force adjustment control to adjust the driving force transmitted to the downstream side of the clutch on the basis of the estimated temperature of the clutch.