Steering Lock Driving Circuit Latch Mechanism
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Solution Overview
Problem
Conventional electronic steering lock systems malfunction, leading to unintended locking or unlocking of the steering shaft, especially when the microcomputer is starting up or experiences errors, and this can be inconvenient for passengers who need to start the engine with the shift position set to 'N'.
Innovation Solution
A steering lock driving circuit and device that includes a microcomputer, latch circuit, OR circuit, AND circuit, unlock sensor, and motor, which outputs a drive permission signal based on specific conditions such as the shift position and vehicle speed, ensuring accurate locking and unlocking of the steering shaft without errors due to microcomputer malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the condition for releasing steering lock includes a state in which the shift position signal is 'P' (to prevent erroneous release due to microcomputer malfunction), then the reliability of steering lock control is improved, but the ease of operation deteriorates because engine start is not allowed unless the shift position is 'P' and passengers find it inconvenient
Solution Approach 1:
The patent introduces a latch circuit as an intermediary component between the microcomputer and the steering lock control system. The latch circuit holds the unlock signal once generated, preventing direct microcomputer errors from causing unintended lock release while allowing the steering lock to be released under appropriate conditions regardless of shift position. This mediator resolves the contradiction by filtering out erroneous signals while preserving legitimate unlock commands.
2Device complexity
If the integrated microcomputer directly controls steering lock release without additional protection circuits, then the device complexity is reduced, but the reliability deteriorates because the microcomputer may erroneously output unlock signals during startup or malfunction
Solution Approach 1:
The patent implements a latch circuit that anticipates and prevents potential microcomputer errors before they can cause unintended steering lock release. The latch circuit is designed to hold the unlock signal only when properly generated, providing a buffer against future errors during microcomputer startup or malfunction. This beforehand cushioning approach adds minimal complexity while significantly improving reliability.
3Reliability
If the shift position must be 'P' for steering lock release (to ensure accurate control), then the reliability of steering lock positioning is improved, but the productivity deteriorates because passengers have to retry engine start when changing shift position quickly
Solution Approach 1:
The latch circuit performs preliminary action by holding the unlock signal once generated, ensuring the steering lock is fully released before the engine start process begins. This preliminary locking release action prevents situations where the lock bar has not reached the unlock position yet, eliminating the need for retry operations when passengers quickly change shift position during engine start attempts.
Data Source
AI summary
A steering lock driving circuit includes: a microcomputer that, based on a detected condition of a vehicle, outputs one of a lock command for restricting rotation of a steering shaft by a rock member to carry out steering lock and an unlock command for releasing the steering lock; a latch circuit that, when an unlock signal indicating that the lock member is located in an unlock position is input to the latch circuit, holds the unlock signal; an OR circuit to which a logical NOT signal of a signal output from the latch circuit and a parking signal indicating that a shift position is a parking position are input; and an AND circuit to which one of the lock command and the unlock command, a signal output from the OR circuit and a condition coincidence signal generated when information detected from the vehicle satisfies a predetermined condition are input.