Latching Relay Failsafe Control for Refrigerant Leak Mitigation
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Solution Overview
Problem
Existing failsafe systems in refrigerant systems, which rely on relays, can become unreliable due to years of non-use and ambient conditions, posing a risk of accidental refrigerant buildup in enclosed areas.
Innovation Solution
A control circuit with a latching relay, power loss detection, and failsafe operation mechanisms, including a watchdog circuit, fan control, compressor control, and power loss activation circuit, to ensure reliable relay operation and initiate emergency mitigating actions during power loss or component failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a latching relay is used in a failsafe system, then the system can maintain relay state during power loss, but the relay may become unreliable after years of non-use and exposure to ambient conditions
Solution Approach 1:
The system performs preliminary actions by periodically activating the relay during normal operation to prevent it from remaining completely idle. The relay is cycled through states and reinforced with control signals to maintain its operational reliability even during extended periods between actual fault conditions.
Solution Approach 2:
The control circuit implements periodic action by sending reinforcement signals to the relay at regular intervals during normal operation. This periodic activation keeps the relay mechanism engaged and functional, preventing degradation that would occur with complete non-use, while still maintaining the failsafe capability during actual power loss or fault conditions.
2Reliability
If the relay is continuously monitored and reinforced during normal operation, then relay reliability is improved, but energy consumption increases
Solution Approach 1:
The system applies partial action by providing relay reinforcement signals at reduced power levels or for shorter durations than would be required for full activation. This allows the relay to be kept in a stable state with minimal energy input, balancing reliability maintenance with energy conservation during normal operation.
Solution Approach 2:
The control circuit prepares the relay for potential failsafe operation by maintaining it in a known good state during normal operation through periodic reinforcement. This preliminary preparation ensures the relay will function correctly when needed without requiring continuous full-power activation, thus reducing energy consumption while maintaining reliability.
3Reliability
If the system implements comprehensive power loss detection and watchdog circuits, then failsafe operation is improved, but device complexity increases
Solution Approach 1:
The system merges multiple functions into integrated circuits where possible. The watchdog circuit and power loss detection are combined with the relay control logic, allowing a single control circuit to perform multiple functions (normal operation control, relay reinforcement, fault detection, and failsafe activation) rather than requiring separate dedicated circuits for each function.
Solution Approach 2:
The control circuit is designed with multi-functionality to handle both normal operation and failsafe conditions through a unified architecture. The same control circuit that manages relay operation during normal conditions also detects power loss and initiates failsafe sequences, eliminating the need for completely separate detection and response systems.
Data Source
AI summary
A control circuit includes a latching relay, a power loss activation circuit, and a watchdog circuit. A microcontrol unit (MCU) communicates with the watchdog circuit in a normal operation of the control circuit. As an action of a failsafe precaution in the event of a main power loss or a component failure, the MCU stops communicating with the watchdog circuit, at which point the watchdog circuit instructs the power loss activation circuit to continue operation of the control circuit. The control circuit further operates to implement mitigation operations in the event of a main power loss or component failure.