Hybrid Vehicle Shift Scheduling Using Battery State of Charge

The patent divides the operational range into multiple segments based on vehicle speed (below trigger speed and above trigger speed). Each segment has its own optimized shift schedule, allowing the system to achieve high fuel efficiency in each segment without requiring a single complex schedule for the entire range. The controller selects between first and second shift schedules based on whether vehicle speed is below or above the trigger speed.

The patent implements dynamic shift schedule selection that adapts to changing operating conditions. The controller dynamically switches between different shift schedules based on real-time vehicle speed relative to the trigger speed and battery state of charge. This dynamic adaptation allows the system to optimize fuel efficiency across varying operational conditions without requiring manual intervention or complex driver input.

The patent segments the operational range at a trigger speed threshold, creating distinct control regions. Below the trigger speed, the first shift schedule optimizes for acceleration and performance. Above the trigger speed, the second shift schedule optimizes for fuel efficiency and reduces unnecessary shifts. This segmentation allows each schedule to be tuned for its specific operational context, preventing the performance degradation caused by overly aggressive shift schedules during cruising.

The patent applies different shift schedule characteristics to different operational regions. The first shift schedule uses performance-oriented shift points suitable for low-speed acceleration, while the second shift schedule uses efficiency-oriented shift points suitable for high-speed cruising. This local optimization ensures that each region receives the appropriate shift behavior, avoiding the energy waste from applying a single aggressive schedule across all conditions.

The patent segments the control strategy into speed-based regions (below and above trigger speed) and within each region, further segments based on battery state of charge thresholds. This creates a hierarchical segmentation that efficiently utilizes the battery SOC degree of freedom without requiring complex continuous control. The controller checks SOC against thresholds within each speed region to select appropriate shift schedules, maintaining simplicity while capturing hybrid vehicle advantages.

The patent introduces battery state of charge as an intermediary parameter that mediates between vehicle speed and shift schedule selection. Rather than directly controlling shifts based only on speed and pedal position, the SOC acts as an intermediary that influences schedule selection, enabling the system to leverage battery charging opportunities during deceleration and optimize shifts based on energy availability without requiring complex real-time optimization algorithms.