Appliance Latch Bi-Stable Bolt Locking Against Bounce Back
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Solution Overview
Problem
Existing washing machine lid locking mechanisms are prone to 'bounce back' and vibration-induced failures, and require bidirectional actuators, which can be complex and prone to contamination, necessitating a more reliable and simpler solution for ensuring the lid is fully locked during the spin cycle.
Innovation Solution
A spring-biased bolt mechanism with a bi-stable mechanical linkage allows for unidirectional actuator use, ensuring full locking engagement and automatic retraction when the lid is not closed, eliminating the need for separate lid closure sensors and providing a reliable electrical signal for safe appliance operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bidirectional actuator is used to control the lock bolt, then the bolt can be extended and retracted reliably, but the device complexity increases and the actuator is more prone to contamination
Solution Approach 1:
The patent extracts the bidirectional control function from a single complex actuator and replaces it with a unidirectional actuator combined with a spring mechanism. The spring provides the return force automatically, eliminating the need for the actuator to perform reverse motion, thus simplifying the actuator design while maintaining reliable bolt positioning.
Solution Approach 2:
The patent replaces the electrical bidirectional control system with a mechanical spring-based return system. The spring automatically pushes the bolt back to its initial position, substituting the need for electrical reverse actuation and reducing the complexity of the control system.
2Reliability
If the lock bolt is extended fully to ensure engagement, then the locking reliability improves, but the bolt may bounce back or fail to maintain engagement due to vibration
Solution Approach 1:
The patent incorporates a spring mechanism that applies continuous force to the bolt, providing a cushioning effect that compensates for vibration and bounce-back. The spring ensures the bolt maintains full engagement with the latch plate even under vibrational conditions, preventing loss of locking reliability.
Solution Approach 2:
The patent changes the force parameter applied to the bolt by introducing a spring mechanism. Instead of relying solely on the actuator to maintain position, the spring continuously applies a force that pushes the bolt into full engagement, dynamically compensating for vibration and ensuring stable positioning.
3Device complexity
If a spring-biased mechanism is used with unidirectional actuator, then the device complexity reduces and power consumption decreases, but the bolt must be precisely controlled to achieve full engagement
Solution Approach 1:
The patent uses the spring as a counterforce mechanism that automatically compensates for positioning variations. The spring force ensures that even if the unidirectional actuator does not extend the bolt to the absolute maximum position, the spring will push the bolt into full engagement with the latch plate, eliminating the need for extremely precise actuator control.
4Strength
If the bolt mechanism is designed to resist external forces, then the locking strength improves, but the actuator requires more force to operate
Solution Approach 1:
The patent applies preliminary action by using the spring to continuously pre-load the bolt into engagement with the latch plate. This preliminary spring force ensures that when external forces are applied during operation, the bolt is already in a strong engaged position, providing locking strength without requiring the actuator to continuously overcome large external forces.
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
The solution provides reliable lid locking with reduced complexity and power consumption, ensuring safety and efficient operation by using a spring to maintain bolt engagement and a bi-stable linkage for unidirectional actuation, allowing for the use of simpler actuators like DC motors or solenoids.
Implementation Method 1
incorporating a spring into the bolt mechanism that biases the bolt outward to fully engage the lid
Implementation Method 2
A bi-stable mechanical linkage is attached to the bolt to hold the bolt at a stable position resisting movement by the spring
Implementation Method 3
An electromechanical actuator operates to receive an electrical signal to apply a force to the bolt
Data Source
AI summary
A door locking mechanism for an appliance provides a bolt that is biased by a spring but may be moved by a unidirectional actuator. A bi-stable mechanism blocks movement of the bolt at certain positions at successive actuations of the unidirectional actuator. In this way, energy need not be provided to the electromechanical actuator except periodically.