Electric Power Steering Self-Checking Logic for Abnormal Sound Prevention
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Solution Overview
Problem
Conventional electric power steering systems fail to detect abnormalities occurring after the ignition switch is turned off due to a lack of initial checking, leading to potential delays and sonic booms when the system is restarted, which affects reliability and user experience.
Innovation Solution
An electric power steering apparatus that performs initial checking upon every operation start, determining necessary checking items based on previous operation results, and excludes conduction/interruption operations of power interruption means when restarting before a predetermined delay, ensuring the system operates efficiently and quietly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If initial checking including power interruption means is performed every time the ignition switch is turned on, then abnormality detection reliability is improved, but checking time is extended and sonic booms occur during power interruption means operation
Solution Approach 1:
The patent applies partial action by performing only necessary checking items based on the previous operation state. When the ignition switch is turned on again before the predetermined delay time elapses, the system determines that power interruption means checking is unnecessary and skips this item, thereby reducing checking time and avoiding sonic booms while maintaining adequate abnormality detection capability.
2Reliability
If power interruption means is operated during initial checking, then conduction state is ensured, but abnormal sounds occur and merchantability is aggravated
Solution Approach 1:
The patent extracts the power interruption means checking item from the initial checking process under specific conditions. When the ignition switch is turned on again before the predetermined delay time elapses, the system excludes power interruption means checking from the necessary checking items, thereby eliminating the source of abnormal sounds while maintaining adequate system reliability through other checking items.
3Speed
If assist start condition is set to input waiting state without initial checking when ignition switch is turned on before delay time elapses, then assist start delay is prevented, but abnormality occurring after previous initial checking cannot be detected
Solution Approach 1:
The patent applies partial action by performing a reduced set of checking items tailored to the specific operational context. When the ignition switch is turned on again before the predetermined delay time elapses, the system performs checking items except power interruption means checking, thereby achieving a balance between quick assist start and adequate abnormality detection for the given situation.
Data Source
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AI summary
An electric power steering apparatus is provided that can prevent an abnormal sound from causing while shortening the initial checking time when the ignition switch is turned to on state again before the elapse of the predetermined delay time since the ignition switch is turned to off state. The electric power steering apparatus comprising: a steering assisting control means that controls driving an electric motor of the steering assisting mechanism; and a self-checking means (steps S21 to S46) that performs an initial checking including a checking of a power interruption means at least when the ignition switch is turned to on state and, allows the steering assisting control means to operate when there is no abnormality to operate in a result of the initial checking of the steering assisting control means, wherein the self-checking means is configured to determine checking items for being executed in the next initial checking on the basis of a checking result in a period until the ignition switch is turned to off state since the steering assisting control means operates (step S45).