Vehicle Drive Force Control for Stability Under Overheating Limits
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Solution Overview
Problem
Conventional techniques for managing driving stability in vehicles with multiple drive sources, such as those described in JP 2012-095378 A, face challenges in maintaining stability due to rapid decreases in driving force that can lead to overheating, making it difficult to sustain stable traveling performance over time.
Innovation Solution
A vehicle control device that includes a first determination unit to assess a first condition, a second determination unit to assess a second condition, and a control unit to execute a second driving force limiting process, which adjusts the rate of decrease in driving force based on these conditions, specifically using a first rate of decrease when the second driving force limiting process is not executed and a second, slower rate of decrease when the second condition is met, thereby managing driving force distribution to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the second driving force is rapidly decreased to prevent overheating, then the overheating problem is mitigated, but the traveling stability deteriorates
Solution Approach 1:
The patent applies dynamics by making the rate of decrease of the second driving force variable rather than fixed. The control unit adjusts the rate of decrease based on real-time temperature conditions and driving state, transitioning between different control modes (first rate when temperature is normal, second rate when temperature is high). This dynamic adjustment allows the system to balance overheating prevention with traveling stability maintenance.
Solution Approach 2:
The patent changes the parameter of driving force reduction rate based on temperature conditions. When the temperature of the second driving source exceeds a threshold, the system switches from a first rate of decrease to a second rate of decrease (which is smaller). This parameter change enables the system to prevent overheating while minimizing the impact on traveling stability by reducing the driving force more gradually under high-temperature conditions.
2Stability of the object's composition
If the second driving force is limited to maintain stability, then the traveling stability is maintained, but the cooling efficiency decreases
Solution Approach 1:
The system dynamically adjusts the driving force limitation based on real-time temperature feedback. When temperature rises above the threshold, the control unit increases the rate of decrease of the second driving force, enhancing cooling efficiency. When temperature is within normal range, the system maintains a smaller rate of decrease to preserve traveling stability. This dynamic response resolves the contradiction by adapting the control strategy to current thermal conditions.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the temperature of the second driving source and adjusting the driving force limitation accordingly. The control unit receives temperature information and modifies the rate of decrease of the second driving force based on whether the temperature exceeds the threshold. This feedback mechanism enables the system to balance stability and cooling efficiency by responding to actual thermal states rather than using fixed control parameters.
3Device complexity
If a single rate of decrease is used for the second driving force, then the control is simple, but the traveling stability cannot be maintained under varying temperature conditions
Solution Approach 1:
The patent segments the control of the second driving force into two distinct modes based on temperature conditions. The control unit determines whether to apply a first rate of decrease or a second rate of decrease depending on whether the temperature exceeds the threshold. This segmentation allows the system to handle different operational conditions with appropriate control strategies, maintaining traveling stability across varying temperature scenarios while keeping the control logic structured and manageable.
Data Source
AI summary
The vehicle control device decreases the second driving force at a first rate of decrease when limiting the second driving force in a state where the second driving force limiting process is not executed, and decreases the second driving force at a second rate of decrease smaller than the first rate of decrease when the second determination unit determines that the second condition is fulfilled in a state where the second driving force limiting process is executed.