Method and actuator for detecting blocking of control valve regulating flow of fluid
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Solution Overview
Problem
Existing HVAC systems face inefficiencies and risk of actuator damage due to control valve failures, particularly when the valve member becomes blocked, leading to excessive torque application by the HVAC actuator, which can result in overheating and damage.
Innovation Solution
A method for operating a control valve using an HVAC actuator that involves monitoring the rotation angle and drive torque, detecting blockages by a threshold angle, and controlling the actuator to alternate between higher and lower torque values, as well as modulating the torque to efficiently release blockages without causing harm to the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HVAC actuator applies a large driving torque to overcome valve blocking, then the valve can be opened, but the actuator may overheat and be damaged
Solution Approach 1:
The actuator applies torque periodically in pulses rather than continuously, alternating between applying torque and coasting. This periodic action allows the actuator to overcome valve blocking gradually without sustained high torque that would cause overheating and damage.
Solution Approach 2:
The actuator dynamically adjusts its operation between different states: applying torque, coasting, and detecting blocking. This dynamic operation allows the system to respond to blocking conditions in real-time and adjust torque application accordingly, preventing damage while maintaining effectiveness.
2Reliability
If the actuator uses a large torque range to handle blocking, then it can overcome blockages, but the actuator becomes overdimensioned and less efficient
Solution Approach 1:
By using periodic torque application with coasting phases, the actuator achieves the ability to handle blocking without requiring a continuously large torque capacity. The periodic pulses accumulate effect over time, allowing a smaller, more efficient actuator to perform the function of what would otherwise require an overdimensioned continuous torque source.
3Reliability
If the actuator continuously applies high torque to ensure valve operation, then the valve can be opened reliably, but energy consumption increases and the actuator overheats
Solution Approach 1:
The actuator applies torque in periodic pulses rather than continuously, significantly reducing energy consumption. The coasting phases between torque applications allow the system to maintain momentum and continue valve opening without additional energy input, while still achieving reliable valve operation through cumulative torque effect.
Solution Approach 2:
The system converts the potential harm of insufficient torque into a benefit by using coasting phases. During coasting, the actuator maintains valve movement momentum without energy consumption, and the periodic torque pulses are sufficient to overcome blocking when applied at the right moments, converting what would be energy waste into efficient operation.
Data Source
AI summary
A method for operating a control valve using an HVAC actuator is described, the method comprises a circuit of the HVAC actuator executing the steps of: monitoring (S1) a rotation angle (ϕ) associated with a drive torque (Mdrive) applied by the HVAC actuator for moving the valve member; detecting (S2) a blocking of the control valve, if the applied drive torque (Mdrive) effects a change of the rotation angle (Δϕ) which is smaller than a threshold angle (ϕth); upon detection of the blocking, controlling the HVAC actuator to repeatedly change the applied drive torque (Mdrive) between a first torque value (M1) and a second torque value (M2); and controlling the HVAC actuator to periodically modulate (S4) the first torque value (M1) between a third torque value and a fourth torque.