Active Front Steering Lock Pin Noise Reduction
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Solution Overview
Problem
The active front steering system's locking solenoid generates an objectionable 'click' noise during vehicle shutdown due to the solenoid pin's acceleration and contact with the locking disc, necessitating a solution that maintains functionality while eliminating noise.
Innovation Solution
The implementation of a pulse width modulation (PWM) signal control for the solenoid coil, combined with a current sensor, to gradually reduce the magnetic force and decelerate the pin before locking, along with potential sound-deadening materials, to minimize noise during shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid and locking pin are used as a lock actuator for an AFS system, then the locking function is achieved, but objectionable 'click' noise is generated during shutdown
Solution Approach 1:
The patent applies preliminary action by gradually reducing the current to the solenoid coil before complete shutdown, which gradually reduces the magnetic force and decelerates the pin before it contacts the locking disc. This preliminary deceleration action prevents the sudden impact that causes the objectionable click noise, while still achieving the required locking function.
Solution Approach 2:
The patent changes the parameter of current supplied to the solenoid coil from a sudden cutoff to a gradual reduction. By controlling the current decay rate, the magnetic force decreases progressively, which slows down the pin's movement and eliminates the impact noise when the pin contacts the locking disc, while maintaining the locking reliability.
2Productivity
If current is suddenly removed from the solenoid coil during shutdown, then the locking action is completed quickly, but the pin accelerates rapidly causing noise
Solution Approach 1:
The system performs preliminary deceleration by gradually reducing current before the pin reaches the locking disc. This preliminary action ensures the pin is already slowing down before impact, eliminating noise while still achieving quick locking through the controlled current reduction profile.
Solution Approach 2:
The patent uses periodic or pulsed current reduction rather than sudden cutoff. By applying current in a controlled, gradually decreasing manner, the magnetic force is maintained just enough to control the pin's descent speed, preventing impact noise while completing the locking action efficiently.
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
This approach effectively reduces or eliminates the noise associated with the locking mechanism while ensuring the active front steering system operates correctly, meeting customer and regulatory requirements.
Implementation Method 1
When the current is removed from the solenoid coil, the solenoid pin begins to accelerate from the force of the coil spring
Implementation Method 2
gradually reduce the magnetic force and decelerate the pin before locking
Implementation Method 3
the solenoid pin begins to accelerate from the force of the coil spring of the solenoid which biases the locking pin toward the locked position
Data Source
AI summary
A vehicle including an active front steer system including a locking mechanism having a solenoid actuated locking pin and a spring for biasing the pin toward an extended or locked position for engaging a locking disc of the active front steer system wherein the active front steer system further includes a current sensor for sensing the motion of the pin of the solenoid when the engine of the vehicle is shut down and pulse width modulated current to the solenoid is reduced and when the pin movement is sensed, the pulse width modulated current is increased (fed forward duty cycle) to reduce the movement of the pin to reduce the noise made when the metal pin makes when contacting the metal locking disc. The end of the pin and/or the locking disc may also include an insulating material to further reduce any remaining noise made when the metal pin makes when contacting the metal locking disc.