Vehicle Control Device Temperature Estimation Prohibition
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Solution Overview
Problem
In vehicles with frictional engagement elements, incorrect temperature estimation occurs when the range switching valve is at an intermediate position, leading to overheating and reduced durability due to improper lubrication, as the system mistakenly engages the frictional engagement element despite lack of hydraulic pressure.
Innovation Solution
A vehicle control device and method that includes determination means for the inhibitor switch signal and oil path state, prohibiting temperature estimation when the inhibitor switch indicates a traveling position and the oil path is in a drain state, ensuring accurate engagement status and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature estimation is performed based on inhibitor switch signal indicating traveling position, then the frictional engagement element is determined to be engaged and temperature control is activated, but the temperature estimation becomes incorrect when the oil path is in drain state causing unnecessary protection control
Solution Approach 1:
The temperature estimation process is segmented into multiple determination steps: first determining engagement status based on inhibitor switch signal, then separately determining oil path state, and only performing temperature estimation when both conditions indicate actual engagement. This segmentation prevents incorrect temperature estimation by breaking the single-step estimation into conditional stages.
Solution Approach 2:
The oil path state determination acts as an intermediary check between the inhibitor switch signal and temperature estimation. By introducing this intermediate verification step, the system ensures that temperature estimation only occurs when both the engagement signal and oil path state confirm actual engagement, preventing false temperature readings.
2Temperature
If the frictional engagement element is engaged while slipping, then heat is generated in the frictional engagement element, but the durability is reduced due to overheating
Solution Approach 1:
The system continuously monitors the oil path state and inhibitor switch signal to provide feedback on actual engagement status. This feedback mechanism ensures that temperature estimation and subsequent cooling control are activated only when genuine engagement occurs, preventing both overheating during actual engagement and false protection control during non-engagement states.
Solution Approach 2:
The oil path state determination is performed preliminarily before temperature estimation to ensure the frictional engagement element is actually engaged. This preliminary check prevents subsequent temperature estimation errors and ensures that cooling measures are applied at the appropriate time, protecting durability while managing heat generation.
Data Source
AI summary
A vehicle control device for controlling a vehicle with a frictional engagement element provided between a drive source and drive wheels includes a first determination unit configured to determine whether or not a signal of an inhibitor switch indicates a traveling position, a second determination unit configured to determine whether or not an oil path communicating with the frictional engagement element is in a drain state, a temperature estimation unit configured to estimate temperature of the frictional engagement element, and a temperature estimation prohibition unit configured to prohibit temperature estimation of the frictional engagement element by the temperature estimation unit when the signal of the inhibitor switch indicates the traveling position and the oil path is in the drain state.