Relay Acoustic Noise Reduction via Current Control
Solution Overview
Problem
Relays generate significant acoustic noise during connection and disconnection due to the rapid movement of contacts, which is not effectively mitigated by existing technologies, and manufacturers face challenges in producing low-noise relays at reasonable costs without resorting to single-sourced components.
Innovation Solution
A circuit that controls the current to the relay coil to slow the movement of contacts by limiting and diverting the current during closing and opening, using capacitor-based current control circuits to gradually close and open the contacts, thereby reducing acoustic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional relay operation is used, then the relay can perform connection and disconnection functions, but significant acoustic noise is generated due to rapid contact movement
Solution Approach 1:
The circuit performs preliminary action by controlling the current rise time before contacts close and current decay time before contacts open. By预先 (in advance) limiting the rate of current change through RC circuits, the contacts move more slowly during the critical closing and opening phases, preventing sudden impacts and reducing acoustic noise before it can occur.
Solution Approach 2:
The invention changes the electrical parameters (current magnitude and rate of change) to control mechanical parameters (contact movement speed). By adjusting the current waveform characteristics through circuit components like resistors and capacitors, the contact movement speed is controlled to reduce noise while still achieving reliable connection and disconnection.
2Object-affected harmful factors
If current is limited to slow contact movement, then acoustic noise is reduced, but the relay operation time is extended
Solution Approach 1:
The circuit applies partial action by controlling current only during the critical transition phases (closing and opening) rather than throughout the entire relay operation. The RC circuits limit current change rates only when contacts are moving, allowing full current flow during stable closed and open states, thus reducing noise during transitions without significantly extending overall operation time.
3Ease of manufacture
If standard relay components are used, then the relay can be manufactured at reasonable cost, but acoustic noise remains significant and cannot be effectively mitigated
Solution Approach 1:
The invention introduces intermediary components (resistors, capacitors, and control circuitry) between the power source and the relay coil. These intermediary elements control the current waveform and indirectly control contact movement speed, reducing acoustic noise without requiring specialized low-noise relay components, thus maintaining reasonable manufacturing costs while effectively mitigating noise.
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 solution effectively reduces acoustic noise during relay operations by controlling the speed and impact of contact movements, making the noise levels acceptable without the need for specialized low-noise relays or single-sourced components.
Implementation Method 1
a first capacitor based current control circuit having a connection to the coil of the relay
Implementation Method 2
when a relay coil causes the contacts to come together for a connection
Data Source
AI summary
A system for controlling a relay to reduce acoustic noise of connections and disconnections being made within the relay. An impact of closing and opening contacts in a relay may cause the acoustic noise. For instance, when a relay coil causes the contacts to come together for a connection, an acoustic noise may occur. When the relay coil causes the contacts to separate for breaking a connection, another acoustic noise may occur. Reduction of acoustic noise may be realized by controlling movement of the contacts. The present system may control current to the relay coil to slow the movement of contacts while closing and opening to reduce the acoustic noise.