Relay Contact Arrangement With Serrated Crown for Dry Switching
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Solution Overview
Problem
Existing relay contact arrangements for dry switching loads face challenges in achieving high specific contact pressure and reliable two-point contact without sparking, especially when interacting with smooth contact heads.
Innovation Solution
A contact arrangement featuring a first contact head with a serrated crown and a second contact head without a crown, where the serrated crown is designed with multiple teeth separated by interruptions, and the contact spring is twistable to ensure two-point contact, achieving high contact pressure and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a continuous crown is used on the contact head, then the contact surface area is increased, but the specific contact pressure decreases and reliable two-point contact cannot be ensured
Solution Approach 1:
The continuous crown is segmented into multiple individual contact elements (protrusions) spaced around the circumference. This segmentation reduces the total contact area while concentrating the force onto discrete points, thereby increasing the specific contact pressure and ensuring reliable two-point contact with the mating contact head.
2Stress or pressure
If the contact surface area is reduced to increase specific contact pressure, then contact reliability improves, but the contact heads may miss each other due to asymmetry or misalignment
Solution Approach 1:
The contact head is designed with locally concentrated contact elements (protrusions) at specific positions around the crown circumference. These localized contact points ensure that even with misalignment or asymmetry, at least two contact points will engage with the mating contact surface, maintaining both high specific pressure and reliable electrical contact.
Solution Approach 2:
The crown is designed with an asymmetric distribution of contact elements rather than uniform spacing. This asymmetric arrangement increases the probability that at least two contact elements will align with the mating contact surface, compensating for potential misalignments and ensuring reliable two-point contact.
3Device complexity
If a single contact point is used, then the structure is simple, but electrical disconnection can occur due to foreign layers or surface irregularities
Solution Approach 1:
Instead of a single contact point, the crown is segmented into multiple discrete contact elements (protrusions) distributed around its circumference. This segmentation ensures that even if one contact point fails due to foreign layers or surface irregularities, other contact points remain available to maintain electrical continuity, thereby significantly improving contact reliability.
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 serrated crown design with a twistable contact spring ensures a secure two-point contact with high specific surface pressure, preventing electrical disconnection and enhancing contact reliability in dry switching applications.
Implementation Method 1
the contact spring is designed to be twistable. This ensures that in the closed position there are always two prongs of the first contact head resting on the contact surface of the second contact head
Data Source
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AI summary
The invention relates to a contact arrangement of a relay with a contact head (11) having a crown (17) that surrounds a contact surface (15) and projects beyond the contact surface. According to the invention, to increase contact reliability under dry switching loads, this crown (17) is interrupted at a plurality of points, forming teeth (21) and spaces between the teeth (21). In the closed position of the contact arrangement, this crown contact head rests at an angle against a crownless contact head. The contact spring (23) supporting the movable contact head is designed to be twistable. This results in the crown contact head (11) contacting the adjacent crownless contact head (25) with a high specific surface pressure at at least two small contact points.