Bistable Micro-Relay With Symmetrical Electrothermal Actuation
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Solution Overview
Problem
Conventional micro-relays have a limited service life due to mechanical stress on actuator legs during switching operations, leading to premature damage and reduced functionality, especially when one-sided loading occurs.
Innovation Solution
A bistable micro-relay design featuring two U-shaped electrothermal microactuators with a permanent magnet arrangement and symmetrical heating of actuator legs, allowing for alternating heating to distribute mechanical stress evenly and increasing the number of switching operations, along with a polymer-based microactuator and nickel metal film heating elements for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microactuators with one-sided loading are used for switching operations, then the relay can be actuated, but the actuator leg suffers mechanical stress and damage after fewer switching processes
Solution Approach 1:
The patent applies asymmetry in reverse by creating symmetry - both actuator legs are designed identically and both are heated alternately, transforming the asymmetric one-sided loading problem into a symmetric dual-leg configuration that distributes mechanical stress evenly, preventing premature damage to any single leg
Solution Approach 2:
The patent implements periodic action by alternating the heating of the two actuator legs in a cyclic manner. Instead of continuously heating one leg, the system periodically switches between heating leg 3 and leg 4, allowing each leg to undergo thermal expansion and contraction cycles that distribute mechanical stress and prevent fatigue damage
2Adaptability or versatility
If two separate microactuators are used to achieve bistable switching, then switching functionality is improved, but the device complexity and mechanical coupling increase
Solution Approach 1:
The patent merges two separate microactuator systems into a single integrated U-shaped actuator structure with two legs (3 and 4) that share a common base. This consolidation maintains the bistable switching functionality while eliminating the need for complex mechanical coupling between separate actuators, reducing overall device complexity
Solution Approach 2:
The U-shaped actuator structure serves multiple functions simultaneously: it provides both actuator legs for bistable switching, acts as its own mechanical coupling through the shared base, and enables symmetric stress distribution. This multi-functionality eliminates the need for separate coupling mechanisms
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 bistable micro-relay design significantly extends the service life and reduces mechanical stress on actuator legs, enabling more efficient and reliable switching operations while minimizing material usage and production costs.
Implementation Method 1
One of the two legs of the microactuators can be heated and expands when heated. The heating is usually generated by a resistance element which is arranged in or on the leg in question and which can be supplied with current in a suitable manner.
Implementation Method 2
Due to the heating-related expansion of a first leg of a micro-actuator relative to a second leg of the micro-actuator, the connection section of the micro-actuator is displaced.
Implementation Method 3
The permanent magnet arrangement consists of two spaced-apart permanent magnets between which a magnetic field is formed.
Implementation Method 4
Depending on the position of the flux element within the magnetic field, the flux element is attracted more strongly by one of the permanent magnets and held in a stable position.
Data Source
Figure 1a~1b
Figure 2
Figure 3~4
AI summary
The invention relates to a bistable microrelay (11) with a pivotably mounted switching contact (12), with at least one electrothermal microactuator (1, 32, 35) with a permanent magnet arrangement (13), with a signal input (16) and with at least one signal output (14, 15). The permanent magnet arrangement (13) is operatively connected to a flux element (21) of the switching contact (12). The switching contact (12) has two contact areas (22) for establishing an electrical connection between the signal input (16) and one signal output (14) or between each of the signal outputs (14, 15) depending on the switching state. The microactuator (1, 32, 35) is U-shaped. The U-shaped microactuator (1, 32, 35) has two actuator legs (31, 34, 39, 41) arranged parallel to each other and connected to each other by a connecting section (4) of the microactuator (1, 32, 35).The end regions (5) of the actuator legs (31, 34, 39, 41) opposite the connecting section (4) are fixed. The length of the actuator legs (31, 34, 39, 41) can be changed by heating. The invention also relates to a microrelay matrix with a number of bistable microrelays (11).