Motor-Driven Compressor Check Valves for Refrigerant Holdback
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Solution Overview
Problem
Motor-driven compressors face insulation deterioration due to liquid refrigerant accumulation, which increases the size requirement and complicates mounting, and leads to excessive pressure and higher torque demands during startup.
Innovation Solution
Incorporating check valves in the suction and discharge passages that are closed during compressor stoppage to prevent liquid refrigerant from entering the housing, ensuring insulation integrity and reducing refrigerant accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an extra length part is provided to extend the insulation distance between the wiring connection part and the housing, then the insulation resistance is improved, but the size of the motor-driven compressor increases
Solution Approach 1:
A resin layer is introduced as an intermediary insulating material between the wiring connection part and the housing. The resin fills the space and provides electrical insulation, allowing the compressor to maintain compact dimensions while achieving sufficient insulation resistance without requiring an extended insulation distance through structural modifications.
2Reliability
If the compressor housing is sealed to prevent liquid refrigerant accumulation, then insulation is maintained, but pressure buildup during startup increases
Solution Approach 1:
The harmful liquid refrigerant is extracted from the housing through dedicated drainage paths (suction and discharge passages) while the housing remains otherwise sealed. This allows the housing to maintain insulation integrity and prevent widespread liquid accumulation, while simultaneously providing controlled egress for liquid refrigerant to avoid dangerous pressure buildup during startup.
Solution Approach 2:
Check valves are introduced as intermediary components in the drainage passages. These valves remain closed during normal operation to maintain sealing and insulation, but open automatically when liquid refrigerant accumulates, providing a controlled release mechanism that prevents both insulation deterioration and excessive pressure buildup.
3Reliability
If check valves are added to prevent liquid refrigerant flow, then insulation is protected, but device complexity increases
Solution Approach 1:
The check valves are designed as passive, self-actuating components that automatically open or close based on pressure differential and liquid refrigerant presence without requiring external control systems. This self-service mechanism protects insulation integrity while minimizing added complexity, as the valves respond autonomously to operating conditions.
4Adaptability or versatility
If the compressor is designed for compact mounting, then vehicle installation flexibility is improved, but space for insulation measures is reduced
Solution Approach 1:
The insulation structure utilizes composite construction combining the resin material with the existing housing structure and wiring arrangement. This composite approach provides effective insulation within the compact space available in vehicle-mounted applications, maintaining both mounting flexibility and insulation reliability without requiring separate dedicated insulation compartments.
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
Prevents liquid refrigerant from accumulating in the compressor housing, maintaining insulation, reducing startup pressure, and enhancing mounting flexibility by minimizing the compressor's size and power consumption.
Implementation Method 1
a check valve that is provided in at least one of the suction passage and the discharge passage, opened while the compressor is in operation and closed while the compressor is at a stop
Data Source
AI summary
A motor-driven compressor includes an electric motor, a compression mechanism driven by the electric motor so as to compress refrigerant gas, a metal housing accommodating the electric motor and the compression mechanism, a suction passage communicable with interior of the housing wherein refrigerant gas flows through the suction passage, a discharge passage communicable with the interior of the housing wherein refrigerant gas discharged from the compression mechanism flows through the discharge passage and a check valve that is provided in at least one of the suction passage and the discharge passage, opened while the compressor is in operation and closed while the compressor is at a stop.