Electric Steering Lock Signal Hold Circuit for Low Voltage
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Solution Overview
Problem
The existing electric steering lock systems erroneously determine the steering shaft's unlock state when the operation voltage decreases, leading to engine start failures due to insufficient battery voltage, especially during cranking or low temperatures.
Innovation Solution
An electric steering lock with a latch mechanism, drive means, detection means, and state holding means, including a non-contact unlock sensor and a hold circuit, which outputs a hold signal to prevent erroneous state determination by maintaining the detection signal's voltage and ensuring correct operation state signaling even at low voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electric non-contact switch (Hall IC) is used to detect the unlock state, then the durability and reliability of the switch is improved, but the output signal voltage decreases when operation voltage decreases, leading to erroneous determination
Solution Approach 1:
A signal hold circuit is introduced as an intermediary between the Hall IC and the engine ECU. This hold circuit maintains the detection signal voltage at a sufficient level even when the operation voltage decreases, preventing erroneous determination while preserving the use of the reliable non-contact switch.
Solution Approach 2:
The invention changes the voltage parameter of the detection signal by using a hold circuit that outputs a signal with voltage maintained at a sufficient level regardless of operation voltage fluctuations. This allows the system to maintain measurement precision despite varying operating conditions.
2Use of energy by moving object
If the battery voltage decreases during cranking or at low temperatures, then the power consumption is reduced, but the unlock switch cannot maintain H level signal output, causing engine start failure
Solution Approach 1:
The signal hold circuit acts as a mediator that ensures the detection signal voltage remains sufficient even when battery voltage decreases during cranking or at low temperatures. This prevents engine start failures while allowing the system to operate under reduced power conditions.
3Loss of energy
If the unlock switch output voltage decreases due to low operation voltage, then the voltage consumption is reduced, but the engine ECU cannot correctly determine the unlock state, leading to false negative determination
Solution Approach 1:
The signal hold circuit serves as an intermediary that preserves the integrity of the operation state information by maintaining sufficient signal voltage levels. This prevents loss of information regarding the unlock state while allowing reduced voltage consumption in the overall system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents erroneous determination of the steering lock mechanism's state, allowing the engine to start correctly even when battery voltage is low by continuously outputting the unlock completion signal, ensuring reliable engine cranking and operation.
Implementation Method 1
An electric non-contact switch having high durability and reliability is used as the lock and unlock switches. An example of such an electric non-contact switch is a Hall IC.
Implementation Method 2
A state holding means, connected to the detection means, generates a hold signal held at a voltage that is the same as that of the detection signal
Data Source
AI summary
An electric steering lock capable of outputting a signal correctly indicating an operation state of a steering lock mechanism even when the operation voltage of a lock detector decreases. The electric steering lock includes a CPU, a signal hold circuit, and an OR circuit. When the steering lock mechanism unlocks a steering wheel, an unlock sensor provides an H level detection signal to the CPU and the signal hold circuit. In response to the detection signal, the CPU issues a state hold command to the signal hold circuit. In response to the state hold command, the signal hold circuit generates an H level hold signal in correspondence with the detection signal. The OR circuit provides an H level signal to an immobilizer ECU when at least one of the detection signal from the unlock sensor or the hold signal has an H level.