Method of controlling a dual clutch transmission

A method of controlling the pressure applied to the engaged clutch of a vehicle having a dual clutch transmission to control the torque transferred across the engaged clutch thereby providing engine speed control for each gear based on the engine throttle position, said method includes the steps of:

• sensing the engine throttle position;
• determining the currently engaged gear of the transmission;
• sensing the speed of the driven member of the engaged clutch;
• selecting an engine stall speed for the current gear and engine throttle position at which the increasing pressure applied to the engaged clutch will stop further engine acceleration and will hold the engine to a constant speed, from a look-up table;
• continuously redetermining a target engine speed based on the engine stall speed and the clutch speed using a target engine speed equation that influences the rate of increase of engine and clutch speed, said target engine speed equation defined as:
• 3 T = S + { [ C + [ K - 2 ) * S ] } 2 4 * ( K - 1 ) * S
• wherein T is the target engine speed, S is the stall speed determined for the current gear and throttle position, C is the clutch speed, and K is a control constant having a value between 1 and 2, said control constant providing control over the rate of clutch engagement and thus the rate of vehicle acceleration, such that the closer K is set to 1 the more rapid and harsher the clutch engagement with sharper engine acceleration, based on predetermined desired vehicle ride characteristics;
• varying the torque transferred across the clutch driving the engaged gear to cause the engine to track the target engine speed based on the difference between the target engine speed and the actual engine speed;
• and
• increasing the applied pressure on the engaged clutch so as to operatively lock the clutch and engine together as the clutch speed reaches a predetermined multiple of the engine stall speed.

A method of controlling the pressure applied to the engaged clutch of a vehicle having a dual clutch transmission to control the torque transferred across the engaged clutch thereby providing engine speed control for each gear based on the engine throttle position, said method includes the steps of:

• determining the engine throttle position;
• determining the currently engaged gear of the transmission;
• sensing the speed of the driven member of the engaged clutch;
• selecting an engine stall speed for the current gear and engine throttle position, at which the increasing pressure applied to the engaged clutch will stop further engine acceleration and will hold the engine to a constant speed, from a look-up table;
• initiating said engine speed control by continuously redetermining a target engine speed based on the engine stall speed and the clutch speed using a target engine speed equation that influences the rate of increase of engine and clutch speed after the clutch speed reaches a predetermined percentage of the engine stall speed, said target engine speed equation defined as:
• 4 T = S + { [ C + [ K - 2 ) * S ] } 2 4 * ( K - 1 ) * S
• wherein T is the target engine speed, S is the stall speed determined for the current gear and throttle position, C is the clutch speed, and K is a control constant, the clutch speed increasing in response to the increasing engine speed;
• varying the torque transferred across the clutch driving the engaged gear to cause the engine to track the target engine speed based on the difference between the target engine speed and the actual engine speed;
• increasing the applied pressure on the engaged clutch so as to operatively lock the clutch and engine together as the clutch speed reaches a predetermined multiple of the engine stall speed;
• and
• ceasing the engine speed control after the clutch speed reaches the predetermined multiple of the engine stall speed.