Relay Contact Chamber Pressure Relief for Arc-Sealed DC Switching
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Solution Overview
Problem
High-voltage DC relays are prone to explosion due to rapid gas pressure buildup in sealed contact cavities during short circuits or overloads, leading to potential ignition and reliability issues.
Innovation Solution
A relay design incorporating a pressure relief valve assembly on the yoke plate that opens when gas pressure exceeds a threshold, allowing gas to escape and preventing explosion, while maintaining sealing in normal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact chamber is sealed to assist in extinguishing the arc, then the arc extinguishing performance is improved, but the contact chamber is prone to explosion under short circuit or overload conditions
Solution Approach 1:
The contact chamber is segmented into a sealed cavity for arc extinguishing and a pressure relief cavity connected via a pressure relief hole. This segmentation allows the sealed cavity to maintain its arc extinguishing function while the pressure relief cavity provides a safe path for pressure release, preventing explosion of the entire contact chamber.
Solution Approach 2:
The pressure relief hole acts as an intermediary element between the sealed contact cavity and the external environment. It remains closed during normal operation to maintain sealing for arc extinguishing, but opens under overpressure conditions to release gas and prevent explosion, thus mediating between the conflicting requirements of sealing and pressure relief.
2Reliability
If the contact chamber is sealed and filled with pressurized gas, then the arc extinguishing capability is enhanced, but the structural integrity is compromised under high pressure conditions
Solution Approach 1:
The contact chamber structure is divided into a sealed cavity that can be filled with pressurized gas for enhanced arc extinguishing, and a pressure relief cavity that serves as a weak link with lower structural strength. This segmentation allows the main sealed cavity to maintain high pressure for arc extinguishing while the pressure relief cavity fails safely at a predetermined pressure threshold.
Solution Approach 2:
The pressure relief cavity or its closure structure is designed as a sacrificial element with deliberately reduced strength. Under extreme overpressure conditions, this element is intended to fail or be broken, providing pressure relief while protecting the main contact chamber structure from catastrophic failure. This disposable element sacrifices itself to preserve the overall system.
3Object-affected harmful factors
If a pressure relief mechanism is added to prevent explosion, then the safety is improved, but the device complexity increases
Solution Approach 1:
The pressure relief function is merged with the existing contact chamber structure by forming a pressure relief cavity within the yoke plate and utilizing the pressure relief hole as part of the chamber architecture. This integration avoids adding separate complex pressure relief mechanisms while still providing effective pressure relief functionality.
Solution Approach 2:
The pressure relief mechanism operates automatically based on the internal pressure conditions without requiring external control systems. The pressure relief hole remains closed during normal operation due to the structural design, and automatically opens when the gas pressure exceeds the structural strength of the pressure relief cavity, providing self-regulating pressure relief.
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 pressure relief valve assembly effectively prevents explosion by releasing excess gas, enhancing the relay's reliability and safety by avoiding disintegration of the sealed cavity.
Implementation Method 1
The pressure relief valve assembly is configured to close the pressure relief hole when a gas pressure in the contact chamber is less than a threshold and configured to be broken to open the pressure relief hole when the gas pressure in the contact chamber is greater than or equal to the threshold
Data Source
Figure 1~2
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Figure 4
AI summary
A relay of the present disclosure includes an insulation cover (21), a first yoke plate (22), a contact assembly (3), a driving assembly (4) and a pressure relief valve assembly (5). The first yoke plate (22) connects with the insulation cover (21) and encloses a contact chamber (27) with the insulation cover (21). The first yoke plate (22) is provided with a pressure relief hole (221). The driving assembly (4) connects with the movable contact piece (32) and drives the movable contact piece (32) move. The pressure relief valve assembly (5) is on the first yoke plate (22) and configured to close the pressure relief hole (221) when a gas pressure in the contact chamber (27) is less than a threshold and configured to be broken to open the pressure relief hole (221) when the gas pressure in the contact chamber (27) is greater than or equal to the threshold.