Compressor Plain Bearing Monitor Using Current Rate Detection
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Solution Overview
Problem
Refrigeration apparatuses face challenges in detecting and addressing poor lubrication in plain bearings, leading to variations in torque and driving current pulsations, which can cause compressor failure.
Innovation Solution
Incorporating a bearing monitor that calculates the rate of change of current and compares it to a reference value to detect abnormal lubrication conditions, triggering an abnormal-state operation to reduce load on the bearings and prevent damage, with the drive shaft's journal portions having a surface roughness of at least 0.05 μm to enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the surface roughness of the journal portion is increased to at least 0.05 μm, then the detection sensitivity of poor lubrication is improved, but the manufacturing precision requirement becomes more stringent
Solution Approach 1:
The patent changes the surface roughness parameter of the journal portion to at least 0.05 μm, which modifies the physical characteristics of the bearing surface. This parameter change enhances the sensitivity of current variation detection for poor lubrication conditions while establishing a clear manufacturing specification that balances detectability with manufacturability
2Reliability
If the bearing monitor continuously monitors the driving current to detect poor lubrication, then the reliability of compressor operation is improved, but the use of energy increases due to continuous monitoring and abnormal-state operations
Solution Approach 1:
The bearing monitor continuously measures the driving current of the compressor and compares it against reference values to detect poor lubrication conditions. This feedback mechanism enables real-time monitoring of bearing health, allowing the system to respond to abnormal conditions while optimizing the balance between reliability and energy consumption through intelligent detection algorithms
3Duration of action of stationary object
If the abnormal-state operation is triggered to reduce load on bearings, then the lifespan of the drive shaft and bearings is extended, but the productivity of the refrigeration apparatus decreases due to operational restrictions
Solution Approach 1:
The system performs abnormal-state operations that reduce the load on bearings before severe damage occurs. By detecting early signs of poor lubrication through current monitoring and implementing protective measures in advance, the system extends bearing lifespan while minimizing the impact on productivity through controlled, preventive actions rather than reactive repairs
Data Source
AI summary
A refrigeration apparatus includes a compressor connected to a refrigerant circuit, and a bearing monitor. The compressor includes a compression mechanism, an electric motor, a drive shaft, and a plain bearing that supports a journal portion of the drive shaft. The bearing monitor performs an abnormal-state operation to cope with poor lubrication on the plain bearing if an abnormal state condition is satisfied. The abnormal state condition is a condition indicating that a rate of change of current exceeds a first reference value. The rate of change of current is an amount of change in a driving current usable to drive the compressor per unit time. The journal portion of the drive shaft has a surface roughness of at least 0.05 μm.