Sealed Compressor Pressure Switch and Fuse Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sealed electric refrigerant compressors fail to reliably interrupt motor energization during sudden rises in refrigerant pressure, leading to potential damage from high pressure and overheating, particularly affecting piping and glass terminals.
Innovation Solution
A sealed electric compressor design featuring a normally-off type pressure switch connected in parallel to the main winding and a fuse element in series with both windings, which short-circuits the main winding upon high pressure detection and interrupts motor energization upon overcurrent, preventing restart and reducing component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thermally responsive protector is used to protect the motor from overcurrent and temperature rise, then the motor can be protected from overload and overtemperature, but the protector cannot reliably detect sudden refrigerant pressure rises and interrupt motor energization in time
Solution Approach 1:
The protection function is segmented into two independent components: a pressure switch for detecting refrigerant pressure abnormalities and a thermally responsive protector for detecting motor temperature and overcurrent. This segmentation allows each component to specialize in its detection function, improving overall protection reliability while maintaining manageable complexity through modular design
Solution Approach 2:
The pressure switch acts as an intermediary device that detects refrigerant pressure changes and converts them into electrical signals to control motor energization. This intermediary mechanism enables indirect detection of pressure conditions that would otherwise be difficult to monitor directly, allowing timely interruption of motor power before damage occurs
2Productivity
If the motor continues to operate during sudden refrigerant pressure rise, then the motor can maintain continuous operation, but high pressure damages piping and glass terminals before the thermally responsive protector can interrupt energization
Solution Approach 1:
The pressure switch is configured to detect refrigerant pressure abnormalities and interrupt motor energization before the high pressure can cause damage to piping and glass terminals. By taking preliminary protective action at the pressure detection stage, the system prevents the development of harmful high-pressure conditions that would otherwise lead to component failure
Solution Approach 2:
The pressure switch provides continuous feedback on refrigerant pressure conditions to the motor control circuit. When abnormal pressure is detected, the feedback signal triggers immediate interruption of motor energization, creating a closed-loop protection system that responds dynamically to pressure changes and prevents damage
3Adaptability or versatility
If the sealed housing is repeatedly subjected to high pressure, then the system can handle pressure fluctuations, but deterioration progresses in weaker parts particularly the glass terminal comprising conductive terminal pins
Solution Approach 1:
The pressure switch provides beforehand protection by detecting pressure rises and interrupting motor energization before the glass terminal and other weaker components can be damaged by repeated high-pressure exposure. This preventive cushioning action eliminates the cumulative deterioration effect that would otherwise occur with repeated pressure cycles
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
Effectively interrupts motor energization during extraordinary pressure and overcurrent conditions, preventing damage to high-pressure components and ensuring reliable operation by preventing repeated high-pressure exposure.
Implementation Method 1
a normally-off type pressure switch disposed in the sealed housing and connected in parallel to the main winding, the pressure switch being operated to short-circuit the main winding when a refrigerant pressure in the sealed housing rises to an extraordinary high pressure state
Implementation Method 2
a fuse element which is connected in series to the main winding and the auxiliary winding and interrupts energization of the motor when an overcurrent flows in the motor with the main winding being short-circuited by the pressure switch
Implementation Method 3
The thermally responsive protector 109 has a thermally responsive contact mechanism (a thermally responsive switch) comprising a thermally responsive element such as a bimetal
Data Source
AI summary
A sealed electric compressor having a normally-off type pressure switch and a fuse element. The pressure switch is placed in a sealed housing, connected parallel to a main winding of an electric motor, and, when the pressure of refrigerant in the sealed housing is abnormally high, activates to short-circuit the main winding. The fuse element is connected in series to the main winding and an auxiliary winding of the electric motor and interrupts conduction of electricity to the electric motor when an excess current that is produced when the pressure switch short-circuits the main winding flows.