Method for detecting a blocked valve of a coolant compressor and a control system for a coolant compressor
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Solution Overview
Problem
Existing methods for detecting a blocked valve in refrigerant compressors are unreliable, as they often fail to accurately identify the blockage state, leading to continuous operation at maximum speed and increased energy consumption, which can be ineffective across various compressor designs.
Innovation Solution
A method involving monitoring parameters such as electric motor current consumption and temperature, where a maximum value is determined after a predefined time, and a percentage decrease is calculated to confirm a blocked valve, allowing for reliable detection and verification of the blockage state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature monitoring is used to detect blocked valves, then shutdown can be triggered when limit temperature is exceeded, but this method does not work for all refrigerant compressor designs as temperature sometimes doesn't rise high enough
Solution Approach 1:
The patent changes the detection parameter from temperature to motor current. Instead of monitoring temperature rise which varies across compressor designs, the invention monitors the electrical current consumed by the motor, which exhibits a consistent characteristic pattern (initial increase to maximum value then decrease) when a blocked valve occurs, regardless of compressor design variations.
2Productivity
If the compressor continues to run at maximum speed after a blocked valve, then cooling capacity is maintained, but energy consumption increases unnecessarily and the blockage worsens
Solution Approach 1:
The patent implements a feedback mechanism where the control system continuously monitors motor current and automatically shuts down the compressor when the characteristic current pattern indicating a blocked valve is detected. This feedback loop prevents unnecessary energy consumption by stopping the compressor at the appropriate time, while also preventing further worsening of the blockage condition.
3Loss of energy
If the compressor is shut down immediately when a blocked valve is detected, then energy consumption is reduced, but the blockage may not be resolved and may recur
Solution Approach 1:
The patent employs periodic action by implementing a restart mechanism after a predetermined time interval following shutdown. The control system shuts down the motor upon detecting a blocked valve, waits for a specified period to allow the blockage to potentially resolve, then restarts the motor to check if normal operation is restored. This periodic on-off-cycling approach balances energy conservation with maintaining operational reliability.
Data Source
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AI summary
A method for detecting a blocked valve of a coolant compressor (1) comprising a drive unit (4) and a piston-cylinder unit for cyclical compression of a coolant, wherein the drive unit (4) has an electric motor for driving the piston-cylinder unit, wherein the speed (ω) of the electric motor is monitored. According to the invention, a maximum speed (ωmax) of the electric motor is initially detected, and the following steps are carried out, as long as the speed (ω) of the electric motor substantially corresponds to the maximum speed (ωmax): determining a maximum value Xmaxof a monitoring parameter (I, T) of the coolant compressor (1); determining a value Xt1of the monitoring parameter (I, T) after a first time period (t1) after determining the maximum value Xmax; detecting a blocked valve if Xt1 is less than Xmax and (Xmax- Xt1) / Xmax≥ Δx applies, wherein Δx is predetermined.