CVT Torque Estimation With Inertia Compensation Across Multiple Ranges
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Solution Overview
Problem
Existing continuously variable transmission (CVT) systems with multiple ranges face reduced accuracy in torque estimation due to the inertia of variator and CVT components, leading to potential 'torque holes' or deficits during rapid acceleration in lower ranges.
Innovation Solution
A method that determines transmission input and output speeds, calculates speed changes, and accounts for inertia torque of multiple components to accurately estimate and adjust torque values, using sensors and predetermined inertia values to refine torque calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the variator accelerates quickly through multiple ranges in lower CVT ranges, then productivity is improved, but measurement precision of torque estimation deteriorates due to inertia effects
Solution Approach 1:
The control system performs preliminary calculations of inertia torque for multiple transmission components (variator, planetary gears, shafts, carriers) before torque estimation, using predetermined inertia values and calculated speed rates of change. This preliminary action allows the system to compensate for inertial effects in advance, maintaining accurate torque estimation even during rapid variator acceleration through multiple CVT ranges
Solution Approach 2:
The invention segments the transmission system into multiple independent components (variator, planetary gears, shafts, carriers) and calculates the inertia torque of each component separately. By reflecting speeds through transmission ratios to each component and calculating individual speed rates of change, the system accurately captures the inertial effects of each segment, enabling precise total torque estimation during rapid acceleration
2Measurement precision
If multiple transmission components are included in torque estimation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The invention uses predetermined inertia values for each transmission component, stored in the control system, which simplifies the calculation process. By changing the approach from real-time inertia measurement to using pre-characterized parameter values combined with calculated speed rates of change, the system achieves high measurement precision while keeping computational complexity manageable through efficient parameter utilization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides more accurate torque estimation and control, mitigating torque deficits by accounting for inertia torque, enabling better management of prime mover input and variator output, thus improving CVT performance during rapid acceleration.
Implementation Method 1
the accuracy of such torque estimates is reduced due to the inertia of the variator and CVT components such as transmission shafts and planetary gears and associated carriers
Data Source
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AI summary
A method is provided for estimating input torque and output torque in a continuously variable transmission having a variator. The method comprising the steps of determining (202) a transmission input and/or output speed, calculating (204) the speed of each of a plurality of transmission components by reflecting the transmission input and/or output speed through the transmission to each of the plurality of transmission components, and calculating (208) the speed rate of change of each of the plurality of transmission components. The inertia torque of each of the plurality of transmission components is calculated (210) based upon its respective speed rate of change and a predetermined component inertia value (209). The method further comprises the steps of determining (211) a motor torque of the variator, and calculating (212) a transmission input torque and transmission output torque by reflecting the motor torque of the variator through the transmission to the transmission input and output. The calculated transmission input and output torque values are adjusted (214) to account for the calculated inertia torque values of those of the plurality of transmission components which lie between the variator and the transmission input, and the variator and the transmission output, respectively.