Blended Gear Ratio Torque Estimation During Transmission Shifts
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Solution Overview
Problem
Existing vehicle systems for sensing transmission output torque are cumbersome, expensive, and lack durability, leading to inaccuracies in torque estimation, especially during gear shifts, which can cause instability and performance issues, particularly in four-wheel drive systems.
Innovation Solution
An apparatus and method that estimate transmission torque output by using a blended gear number to determine a gear ratio that decreases proportionally with torque output, allowing for more accurate torque distribution between wheels during shifts, thereby enhancing shift smoothness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If actual transmission output torque sensing systems are implemented, then torque measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual copy of the torque sensing function through software-based torque estimation algorithms. Instead of physical sensors, the system uses mathematical models that calculate torque based on engine parameters, transmission state, and clutch characteristics, replicating the information function of actual torque sensors without the hardware complexity
Solution Approach 2:
The patent replaces mechanical/physical torque sensing systems with an electronic/software-based estimation system. The control unit uses computational algorithms to determine torque values, substituting physical measurement devices with electronic processing and mathematical modeling
2Ease of manufacture
If constant gear ratio values are used for torque estimation, then calculation simplicity is improved, but torque estimation accuracy deteriorates during gear shifts
Solution Approach 1:
The patent transitions from static constant gear ratio values to dynamic blended gear ratio values that change continuously during gear shifts. The blended gear ratio is calculated based on the transition state between gears, allowing the system to adapt to changing transmission conditions and maintain accuracy throughout the shift process
Solution Approach 2:
The patent changes the gear ratio parameter from fixed constant values to variable blended values during gear transitions. This parameter modification allows the torque estimation to reflect the actual intermediate states during shifting, improving accuracy without significantly complicating the calculation process
3Adaptability or versatility
If multiple clutches are actuated for gear selection, then transmission versatility is improved, but torque fluctuation increases during shifts
Solution Approach 1:
The patent incorporates feedback from clutch actuation state and transmission position into the torque estimation calculation. By monitoring which clutches are engaged and the current gear transition state, the system adjusts the blended gear ratio to compensate for torque fluctuations, using this feedback information to maintain more stable torque estimates during multi-clutch operations
Data Source
AI summary
Some embodiments relate to determining an estimated torque output by a vehicular transmission. A first controller determines a target gear number and an actual gear number during shifting between the gears of the transmission, the target gear number being equal to a value of a gear number to which the transmission is shifting, the actual gear number being equal to a value of a gear number from which the transmission is shifting. A second controller compares the target gear number to the actual gear number and retrieves a blended gear number if the target gear number is greater than the actual gear number, determines an approximate value for a gear ratio that decreases in proportion to a rate of decrease in torque output by the transmission based on the blended gear number, and estimates a value of the torque output by the transmission based on the determined gear ratio.