Clutch Temperature Estimation Using Slippage and Fluid Data
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Solution Overview
Problem
Existing systems for estimating clutch temperatures in mobile machines, such as those described in U.S. Pat. No. 6,769,526 B2, face inaccuracies due to the use of fixed heat rejection rates, leading to low accuracy in determining temperature changes in clutches.
Innovation Solution
A mobile machine propulsion system that includes a prime mover, traction devices, and a clutch, with propulsion-system controls featuring an information processor that estimates clutch temperature based on estimated slippage and fluid temperature, allowing for dynamic adjustments to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed heat rejection rate is used to estimate clutch temperature, then the system complexity is reduced, but the measurement precision of clutch temperature decreases
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed heat rejection rate to a dynamic, variable heat rejection rate that changes based on clutch operating conditions. The heat rejection rate is now determined by monitoring parameters such as clutch slippage, torque, and fluid temperature, allowing the estimation system to adapt to varying operational states and significantly improving temperature estimation accuracy without requiring excessive system complexity
Solution Approach 2:
The patent implements parameter changes by modifying the heat rejection rate parameter from a constant fixed value to a variable parameter that responds to changes in clutch operating conditions. By continuously adjusting the heat rejection rate based on real-time measurements of slippage, torque, and fluid temperature, the system achieves more accurate temperature estimation while maintaining reasonable system complexity through the use of established thermal models
2Adaptability or versatility
If clutch slippage is used to modulate power transmission, then the adaptability of the propulsion system is improved, but the temperature of the clutch increases due to heat generation
Solution Approach 1:
The patent applies the feedback principle by implementing a closed-loop temperature estimation and monitoring system. The information processor continuously estimates clutch temperature based on slippage, torque, and fluid temperature measurements, and this temperature information can be fed back to control the clutch operation. When the estimated temperature approaches unacceptable levels, the system can adjust clutch engagement to prevent overheating, thereby maintaining both adaptability and acceptable temperature levels
Solution Approach 2:
The patent implements beforehand cushioning by proactively monitoring and estimating clutch temperature before damage occurs. By continuously tracking temperature trends based on slippage and operating conditions, the system can take preventive actions such as reducing slippage or increasing cooling fluid flow before the clutch temperature reaches dangerous levels, thus cushioning against potential thermal damage while preserving the benefits of clutch modulation
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 approach enhances the accuracy of clutch temperature estimation and prevents overheating by dynamically monitoring and controlling clutch temperatures, thereby protecting the clutch and other components from damage.
Implementation Method 1
an amount of heat dissipated by the clutch to the fluid
Data Source
AI summary
A mobile machine includes a propulsion system. The propulsion system may include a prime mover, a traction device, and a clutch operable to transmit power produced by the prime mover to the traction device. The propulsion system may also include propulsion-system controls operable to control the clutch. The propulsion-system controls may include at least one information processor configured to estimate a temperature of the clutch based at least in part on an estimated slippage of the clutch and a fluid temperature.