Automatic Transmission Shift Control via Input Torque Detection
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Solution Overview
Problem
Existing automatic transmission systems face challenges in accurately detecting the initial rise time of on-coming clutch torque capacity during shift events, leading to inconsistent shift quality and perceivable shift shocks due to mismatched control timings between the on-coming clutch and other torque-generating devices.
Innovation Solution
A system and method that induce a detectable slope change in the input shaft torque profile by adjusting clutch actuator control parameters, allowing for the accurate detection of the initial rise time of on-coming clutch torque capacity, thereby synchronizing control timing with other torque-generating devices like engines and electric motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hydraulic pressure transducer is used to monitor OCC actuator pressure, then pressure monitoring capability is improved, but accurate detection of initial rise time remains challenging under various operating conditions
Solution Approach 1:
The patent uses transmission input torque as an intermediary parameter to indirectly detect OCC torque capacity. Instead of directly measuring OCC pressure or torque, the system calculates transmission input torque from engine torque and torque converter torque, which reflects the net torque available to the OCC. This intermediary measurement approach enables accurate detection of the initial rise time of OCC torque capacity under various operating conditions without requiring direct OCC sensors.
Solution Approach 2:
The patent replaces direct mechanical pressure sensing in the OCC actuator with a computational approach using torque calculations. By substituting the mechanical measurement system with a torque-based computational model, the system achieves more reliable detection of torque phase initiation across different operating conditions without being constrained by pressure transducer limitations.
2Reliability
If OCC torque capacity is raised in a consistent manner under all operating conditions, then shift quality is improved, but accurate knowledge of initial rise time is difficult to obtain
Solution Approach 1:
The patent implements a feedback mechanism where transmission input torque is continuously monitored and compared against threshold values to detect the initial rise time of OCC torque capacity. The system uses this detected timing information to adjust and synchronize control of other torque-generating devices, creating a closed-loop control system that maintains consistent shift quality across all operating conditions while accurately capturing the torque phase initiation moment.
3Object-affected harmful factors
If control timing of OCC and other torque-generating devices is synchronized, then shift shock is reduced, but accurate timing detection is challenging
Solution Approach 1:
The patent performs preliminary detection of the initial rise time of OCC torque capacity using transmission input torque calculations before finalizing the torque phase control timing. By提前 identifying the torque phase initiation point through the intermediary torque measurement, the system can pre-synchronize the control timing of engine, clutches, and electric motor to eliminate shift shocks.
Data Source
AI summary
A system and method for controlling a vehicle powertrain having a transmission to improve shift quality is based on detection of an initial rise time of an on-coming clutch torque capacity, which indicates the start of the torque phase. The initial rise time is detected using a transmission input shaft torque computation. The system may include a vehicle powertrain having an engine, a transmission coupled to the engine via a torque converter and a controller configured to initiate torque phase control when a difference between a first transmission input shaft torque and a second transmission input shaft torque exceeds a first predetermined threshold parameter during a shift event characterized by a preparatory phase, a torque phase and an inertia phase.