Electromagnetic Relay Contact Timing Control
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Solution Overview
Problem
Existing electromagnetic relays experience contact welding and defects due to arc discharge when handling large energizing currents, leading to unreliable operation and potential failure.
Innovation Solution
The design incorporates a pressing member with a step configuration between contact pressing and detachment portions, using blade springs with varying lengths and materials to control contact timing and heat distribution, ensuring that larger contacts handle arc discharge during both contact and detachment, thereby reducing welding and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross-sectional area of the spring is enlarged to handle large energizing currents, then the spring can withstand higher currents, but the bending of the spring for leading contact rolling cannot be secured adequately
Solution Approach 1:
The spring is divided into multiple segments along its length, with each segment having a different cross-sectional area. The lower portion has a larger cross-sectional area to withstand high currents and resist welding, while the upper portion has a smaller cross-sectional area to provide adequate bending flexibility for contact rolling. This segmentation allows the spring to simultaneously satisfy both requirements that would be contradictory in a uniform spring design.
2Object-affected harmful factors
If rolling of one contact is used to prevent welding, then contact welding is reduced, but when energizing current is large, the spring bending for leading rolling cannot be secured
Solution Approach 1:
Different portions of the spring are given different local qualities through varying cross-sectional areas. The upper portion with smaller cross-sectional area is designed to bend easily to enable contact rolling, while the lower portion with larger cross-sectional area maintains sufficient strength to support the rolling action under large current conditions. This local differentiation of properties allows the spring to achieve both welding prevention through rolling and adequate structural strength.
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 solution effectively manages arc discharge during both contact and detachment, minimizing contact welding and maintaining reliable operation even under large current conditions, with the use of high-conductivity and high-spring-characteristic materials enhancing the relay's performance and durability.
Implementation Method 1
an electromagnet 20, yokes 10, armatures 12... The polarity of the electromagnet is changed, so that the magnetic pole of the yoke is changed. Thereby, the armature comes in contact with the yoke or detaches from the yoke.
Implementation Method 2
an armature magnetized with a permanent magnet. The polarity of the electromagnet is changed, so that the magnetic pole of the yoke is changed. Thereby, the armature comes in contact with the yoke or detaches from the yoke.
Implementation Method 3
The movable contact is biased by an elastic body, and the pressing member presses the elastic body according to the operation of the armature.
Data Source
Figure 1
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Figure 3
AI summary
An electromagnetic relay (100) includes: a first movable contact (30a) that comes in contact with a first fixed contact (40a); a second movable contact (30b) that comes in contact with a second fixed contact (40b); a first elastic body (32a, 36a) that biases the first movable contact; a second elastic body (32b, 36b) that biases the second movable contact; a pressing member (14) that presses the first elastic body and contacts the first movable contact to the first fixed contact, presses the second elastic body and contacts the second movable contact to the second fixed contact; wherein the pressing member contacts the second movable contact to the second fixed contact before contacting the first movable contact to the first fixed contact.