Dynamic Transmission Torque Limiting for Work Vehicle Drivetrain
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Solution Overview
Problem
Current work vehicles face undesirable performance 'feel' and increased complexity due to fixed torque limits, which restrict transmission output torque and lead to reduced drivetrain component lifespan under varying loads.
Innovation Solution
A system and method that dynamically calculates transmission output torque limits based on current and reference transmission speeds using an exponential formula, allowing increased torque as output speed reduces, and determines these limits using drivetrain life data to prevent component damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed torque limits are defined for each transmission gear, then drivetrain components are protected from damage, but operator performance feel deteriorates and system complexity increases
Solution Approach 1:
The patent applies dynamics by transitioning from fixed torque limits to dynamic torque limits that vary continuously with transmission output speed. The torque limit is calculated using the formula T_limit = T_ref * (S_ref / S) ^ m, where the limit adapts in real-time based on operating conditions, allowing higher torque at lower speeds to improve operator feel while still protecting components through speed-dependent limiting
Solution Approach 2:
The patent changes the parameter of torque limit from a constant value to a variable value that depends on transmission output speed. By introducing the speed-dependent relationship T_limit = T_ref * (S_ref / S) ^ m, the system adjusts the torque limit parameter dynamically, resolving the contradiction between component protection and operational performance
2Duration of action of stationary object
If fixed torque limits are defined for each transmission gear, then drivetrain component lifespan is reduced under varying loads, but this approach simplifies control system development
Solution Approach 1:
The patent replaces the mechanical approach of fixed gear-specific torque limits with a mathematical model T_limit = T_ref * (S_ref / S) ^ m that calculates appropriate limits based on transmission output speed. This substitution allows the system to adapt to varying loads and extend component lifespan while maintaining manageable control complexity through a unified formula rather than multiple fixed values
3Reliability
If transmission output torque is capped at fixed limits, then component damage is prevented, but operator has to downshift frequently to maintain torque
Solution Approach 1:
The patent uses dynamics to allow the torque limit to vary with transmission output speed, enabling the operator to maintain higher torque levels across a wider speed range without downshifting. The dynamic formula T_limit = T_ref * (S_ref / S) ^ m automatically adjusts limits to match operating conditions, improving productivity while maintaining component protection
Data Source
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AI summary
A method for enhancing the performance of a work vehicle (10) including storing a reference transmission torque and a reference transmission speed for a transmission (24) of the work vehicle. At least one of the reference transmission torque or the reference transmission speed may be determined based at least in part on drivetrain life data associated with at least one drivetrain component of the work vehicle. In addition, the method may include determining a current transmission speed for the transmission, determining a transmission output torque limit for the transmission based on the current transmission speed, the reference transmission torque and the reference transmission speed and controlling an engine (22) of the work vehicle such that a transmission output torque of the transmission does not exceed the transmission output torque limit while the transmission is being operated at the current transmission speed.