Method and apparatus for optimizing braking control during a threshold braking event

A method of optimizing braking in a hybrid electric vehicle (HEV) having a plurality of drive wheels, a friction braking system having antilock braking system (ABS) capability, and an electronically variable transmission (EVT) having a low speed/high torque EVT mode and at least one high speed/low torque EVT mode, the method comprising:

• measuring a plurality of vehicle performance values including:
• a braking input force and a slip level between the drive wheels and a road surface;
• comparing said plurality of vehicle performance values to corresponding threshold values;
• automatically cycling the friction braking system to thereby activate the ABS capability when each of said plurality of vehicle performance values exceeds a respective one of said corresponding threshold values;
• determining a present deceleration rate of the HEV;
• and
• automatically commanding an upshift of the EVT from the low speed/high torque EVT mode into the at least one high speed/low torque EVT mode when said ABS is activated and when a magnitude of said present deceleration rate is less than a magnitude of a calibrated maximum deceleration rate.

A hybrid electric vehicle (HEV) having a friction braking system with antilock braking system (ABS) capability and an electronically variable transmission (EVT) having a plurality of EVT modes, the plurality of EVT modes including a low speed/high torque EVT mode and at least one high speed/low torque EVT mode, the HEV comprising:

• a plurality of drive wheels for propelling the HEV with respect to a road surface;
• a brake pedal configured to receive a threshold braking input force;
• a friction braking system adapted to slow the HEV in one manner in response to an application of said threshold braking input force to said brake pedal;
• and
• a controller adapted to activate the ABS capability to automatically cycle the friction braking system in response to a threshold level of slip between said drive wheels and said road surface when said threshold braking input force is present, thereby slowing the HEV in another manner;
• and
• at least one sensor adapted to measure a dynamic value used for determining a present deceleration rate of the HEV;
• wherein said controller has an algorithm adapted to automatically shift the EVT from the low speed/high torque EVT mode into the at least one high speed/low torque EVT mode when the ABS capability is activated and when said present deceleration rate has a magnitude that is less than a magnitude of a calibrated maximum deceleration rate, and to automatically retain the EVT in the at least one high speed/low torque EVT mode when the ABS capability is activated while the EVT is already operating in said at least one high speed/low torque EVT mode.