CVT Variator Downshift Control Under Engine Torque-Down

The patent applies dynamics by making the shift speed variable rather than fixed. The control device dynamically adjusts the variator's shift speed during downshift based on whether torque-down is being performed. During torque-down, the shift speed is reduced to prevent inertia torque from exceeding engine torque, while during normal operation, faster shift speed is maintained for responsive acceleration. This dynamic adjustment resolves the contradiction between fast shifting and maintaining acceleration.

The patent changes the parameter of shift speed based on the torque-down state. When torque-down is detected, the control device modifies the shift speed parameter to be slower, ensuring engine torque remains greater than inertia torque. This parameter change directly addresses the contradiction by adapting the shifting characteristics to the current operational conditions, preventing acceleration degradation while maintaining overall system performance.

The patent makes the torque-down application dynamic by selectively applying it only during specific conditions. The control device determines whether torque-down should be performed based on the shift type (auxiliary transmission shift versus variator shift) and the current operational state. By dynamically controlling when torque-down is applied, the system maintains torque stability during necessary shifts while preventing the engine torque from dropping below inertia torque levels that would degrade acceleration.

The patent applies local quality by differentiating the torque management approach for different transmission components and operational states. Instead of applying uniform torque-down across all scenarios, the control device applies torque-down selectively based on the specific shift context. This localized approach ensures smooth shifts where needed while preserving acceleration performance in scenarios where maintaining engine torque above inertia torque is critical.