System for controlling an engine disconnect clutch in a hybrid vehicle

A vehicle comprising:

• an engine having a crankshaft;
• an electric machine having a rotor;
• a disconnect clutch having an input secured to the crankshaft and an output secured to the rotor;
• a hydraulic pump mechanically powered via rotation of the rotor and configured to supply hydraulic fluid to actuate the disconnect clutch;
• a torque converter having an impeller secured to the rotor;
• and
• a controller programmed to,
• responsive to a speed of the impeller decreasing to less than a first threshold, which is indicative of a subsequent shutdown of the hydraulic pump, and responsive to the disconnect clutch being open while the engine is shut down, advance the disconnect clutch to a touch point where opposing sides of disconnect clutch make contact but substantially zero power is transferred between the engine and the electric machine, and
• responsive to the speed of the impeller increasing to greater than a second threshold while the disconnect clutch is at the touch point and the engine is shut down, retract and open the disconnect clutch, wherein the second threshold is greater than the first threshold.

A vehicle comprising:

• a powertrain having an engine and an electric machine each configured to generate power;
• a disconnect clutch disposed between the engine and electric machine;
• a hydraulic pump mechanically powered via rotation of the electric machine and configured to supply hydraulic fluid to actuate the disconnect clutch;
• and
• a controller programmed to,
• responsive to a speed of a rotor of the electric machine decreasing to less than a first threshold, which is indicative of a subsequent shutdown of the hydraulic pump, and responsive to the disconnect clutch being open while the engine is shut down, advance the disconnect clutch to a touch point where opposing sides of disconnect clutch make contact but substantially zero power is transferred between the engine and the electric machine, and
• responsive to the speed of the rotor increasing to greater than a second threshold while the disconnect clutch is at the touch point and the engine is shut down, retract and open the disconnect clutch, wherein the second threshold is greater than the first threshold.