Bi-Stable Appliance Latch With Shock-Blocking Restraint
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Solution Overview
Problem
Bi-stable lock mechanisms in household appliances can inadvertently lock during transportation due to shocks, causing inconvenience as they lack differentiation between electrical actuation and shock forces, leading to increased actuator size and manufacturing complexities.
Innovation Solution
A bi-stable lock mechanism that includes a restraining element sensitive to acceleration, using a weight or magnetically attracted armature to distinguish between electrical actuation and shock forces, allowing movement only under electrical power or compensating for shock forces, thus preventing unintended locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the force of the over-center spring is increased to prevent inadvertent locking during transportation, then the reliability of the lock is improved, but a larger electromagnetic actuator is required which increases device complexity and cost
Solution Approach 1:
A restraining element is introduced as an intermediary component between the actuator element and the external environment. This element selectively restricts movement during transportation shocks while permitting normal actuator operation, thereby preventing inadvertent locking without requiring increased spring force or larger actuators.
Solution Approach 2:
The restraining element changes its mechanical properties based on acceleration conditions. During normal operation, it permits free movement of the actuator element. During transportation shocks (high acceleration), it engages to restrict movement, effectively changing the system's mechanical parameters dynamically to resolve the contradiction between reliability and actuator size.
2Reliability
If frictional elements are added to the latch to prevent inadvertent actuation, then the reliability is improved, but the manufacturing complexity increases and consistent friction is difficult to achieve
Solution Approach 1:
The restraining element serves as a mechanical intermediary that provides shock resistance without relying on friction. By using inertial forces and mechanical engagement rather than frictional elements, the design achieves reliable protection against inadvertent actuation while maintaining ease of manufacture and consistent performance throughout the product lifecycle.
3Use of energy by moving object
If a bi-stable actuator is used to reduce power consumption, then the energy efficiency is improved, but the lock becomes susceptible to transportation shocks causing inadvertent locking
Solution Approach 1:
The restraining element applies preliminary protective action by being positioned to engage and restrict movement before transportation shocks can cause inadvertent locking. This preventive mechanism counteracts the harmful effect of shocks on the bi-stable actuator, allowing the system to maintain low power consumption while becoming resistant to transportation-related failures.
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 ensures reliable and efficient operation by preventing shock-induced locking during transportation, maintaining low actuation thresholds, and utilizing existing solenoid components, while ensuring the lock remains functional only when intended by electrical actuation.
Implementation Method 1
an electromagnetically driven bi-stable actuator. Such an actuator may include a bidirectional solenoid that may either push or pull an actuator element depending on polarity of applied electrical power
Implementation Method 2
A shock-sensitive restraining element may be attached to the latch body and sensitive to acceleration of the latch body to prevent movement of the actuator element with respect to the latch body when acceleration is detected
Implementation Method 3
In another embodiment, the restraining element may be a magnetically attracted armature moved in response to electrical power flowing through a coil
Data Source
AI summary
A transportation-robust bi-stable latch mechanism preserves low actuation forces by means of an auxiliary mechanism blocking the effects of shock forces during transportation.