Four-Wheel Drive Vehicle Control Device Temperature Estimation
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Solution Overview
Problem
Existing vehicle control devices for four-wheel drive vehicles may inaccurately estimate the temperature of the heat generating location in the driving force transmission system, particularly during low μ road conditions where wheel slip occurs, leading to potential overheating issues.
Innovation Solution
A vehicle control device with an electronic control unit that calculates a command torque based on vehicle information and estimates the temperature of the heat generating location using the command torque, even when the driving force corresponding to the torque cannot be transmitted to the auxiliary drive wheels due to wheel slip or the magnitude of the driving force generated by the drive source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature estimation is based on command value of clutch engagement force, then temperature estimation can be performed, but estimation accuracy deteriorates under wheel slip conditions
Solution Approach 1:
The system continuously monitors actual driving force transmission status and compares it with commanded values. When wheel slip is detected (actual transmission < commanded transmission), the estimation method automatically switches from command-value-based to actual-value-based estimation, creating a feedback loop that adapts to changing conditions and maintains accuracy.
Solution Approach 2:
The estimation approach changes parameters based on operating conditions. Under normal conditions, command value parameters are used for estimation. Under wheel slip conditions, the system switches to using actual driving force parameters, effectively changing the estimation parameters to match the actual physical state and improve accuracy.
2Temperature
If driving force transmission to auxiliary drive wheels is reduced to prevent overheating, then heat generation is reduced, but driving performance deteriorates
Solution Approach 1:
The system uses real-time temperature estimation feedback to dynamically adjust clutch engagement force. When temperature approaches thresholds, the control amount is adjusted to reduce heat generation. This feedback mechanism allows the system to prevent overheating while maintaining maximum driving force transmission when conditions permit, resolving the contradiction between temperature control and power delivery.
Data Source
AI summary
A vehicle control device mounted on a four-wheel drive vehicle including a driving force transmission system includes an electronic control unit. The electronic control unit calculates a command torque based on vehicle information. The electronic control unit estimates a temperature of a heat generating location in the driving force transmission system based on the command torque. The electronic control unit estimates the temperature of the heat generating location based on an estimated value of a driving force input to an input rotating member, when it is not possible for the driving force corresponding to the command torque to be transmitted to auxiliary drive wheels due to a magnitude of the driving force generated by a drive source or occurrence of a wheel slip.