Friction Element Temperature Estimation Using Mapping Data
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Solution Overview
Problem
Accurate temperature estimation of friction engaging elements in a transmission system is challenging due to varying heat generation and cooling characteristics among elements, especially when shifting intervals and hydraulic pressure conditions change.
Innovation Solution
A temperature estimation device that uses mapping data to calculate the temperature of friction engaging elements by inputting variables such as heat amount, shifting interval, relative rotation speed, hydraulic pressure, oil temperature, and output torque, considering the unique characteristics of each element to improve estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single temperature estimation model is used for all friction engaging elements, then the device complexity is reduced, but the temperature estimation accuracy for each element deteriorates due to different heat capacity and cooling characteristics
Solution Approach 1:
The patent divides the temperature estimation into separate processes for different friction engaging elements. The calculation unit performs distinct estimation calculations for each element (first friction engaging element and second friction engaging element) using element-specific parameters such as heat capacity, cooling characteristics, and engagement timing. This segmentation allows accurate temperature estimation for each element while maintaining a unified overall system architecture.
2Productivity
If the shifting interval is shortened to improve productivity, then the transmission shifting speed increases, but the temperature estimation accuracy deteriorates because the friction engaging element temperature does not converge to a constant temperature
Solution Approach 1:
The patent implements dynamic temperature estimation that adapts to varying shifting intervals. The calculation unit determines temperature based on actual engagement timing and duration for each shifting operation, rather than assuming a fixed convergence behavior. When shifting intervals are short and temperatures do not converge, the system still performs accurate estimation by using real-time parameters including the actual time elapsed since previous engagement and the current engagement characteristics.
Solution Approach 2:
The system performs preliminary determination of temperature estimation parameters before completing the shifting operation. By calculating the expected temperature rise based on predetermined heat capacity and cooling characteristics, and combining this with actual engagement timing data, the system prepares the estimation framework in advance, allowing accurate temperature calculation even when shifting occurs before thermal convergence.
3Measurement precision
If multiple input variables are used to improve temperature estimation accuracy, then the measurement precision increases, but the device complexity and data processing requirements increase
Solution Approach 1:
The patent employs a universal temperature estimation framework that handles multiple input variables through a unified calculation approach. The same calculation unit processes various parameters (heat capacity, cooling characteristics, engagement timing, rotational speed, hydraulic pressure) using a consistent methodology applicable to all friction engaging elements. This multi-functional approach allows accurate temperature estimation with multiple variables while avoiding the need for separate specialized processing systems for each parameter type.
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
The device provides more accurate temperature calculations by accounting for the specific conditions of each friction engaging element, enhancing the precision of temperature estimation during transmission shifting.
Implementation Method 1
a heat amount variable that is a variable indicating an amount of heat generated by the friction engaging elements during the shifting of the transmission
Implementation Method 2
the cooling effect of the friction engaging elements differs from each other when the friction engaging elements are cooled by hydraulic oil or the like
Data Source
AI summary
A temperature estimation device for friction engaging elements including an execution device and a storage device is provided. The storage device stores mapping data that defines mapping. The mapping includes, as an input variable, a heat amount variable that is a variable indicating an amount of heat generated by the friction engaging elements during the shifting of the transmission and a shifting variable indicating the friction engaging elements to be engaged at the time of the shifting of the transmission, and, as an output variable, the temperature. The execution device executes an acquisition process of acquiring a value of the input variable and a calculation process of inputting the value of the input variable acquired by the acquisition process into the mapping to calculate a value of the output variable.