Scroll Backpressure Control for High-Speed Electric Compressors
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Solution Overview
Problem
Electric compressors in battery-powered vehicles face challenges with high-speed operation leading to noise, inefficiency, and reduced operating life due to improper backpressure management and oil film loss between scrolls.
Innovation Solution
A scroll backpressure system with a first and second pressure pathway, including a dump valve and a backpressure regulator valve, controls refrigerant flow to manage backpressure effectively, preventing excess friction and noise while maintaining efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backpressure is increased to prevent axial separation of scrolls and maintain sealing, then sealing performance is improved, but friction and heat generation increase reducing efficiency
Solution Approach 1:
The backpressure system is segmented into multiple independent pathways: a first pressure pathway with a flow restrictor for continuous backpressure maintenance, and a second pressure pathway with a dump valve for periodic pressure relief. This segmentation allows independent control of sealing pressure and friction prevention, resolving the contradiction between maintaining sealing performance and reducing energy loss.
2Productivity
If compressor operates at high speed to improve productivity, then cooling capacity is improved, but noise level increases
Solution Approach 1:
The backpressure system applies preliminary anti-action by maintaining controlled backpressure before excessive axial separation occurs. The flow restrictor continuously provides backpressure to keep scrolls properly engaged, while the dump valve prevents pressure buildup that would cause excessive friction and noise. This preliminary control allows high-speed operation without the harmful effects of improper scroll loading.
3Reliability
If backpressure is maintained to ensure proper scroll loading, then compression reliability is improved, but oil film between scrolls is lost reducing efficiency
Solution Approach 1:
The backpressure system transitions from static to dynamic control through the combination of flow restrictor and dump valve. The flow restrictor provides continuous dynamic backpressure to maintain scroll loading and reliability, while the dump valve dynamically releases pressure when oil film degradation is detected. This dynamic adjustment maintains the optimal balance between compression reliability and efficiency throughout operation.
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
The system enhances compressor efficiency, reduces noise, and extends operating life by optimizing backpressure to prevent axial separation of scrolls and maintaining proper sealing, thus improving overall performance.
Implementation Method 1
The first pressure pathway is located between the discharge volume and the backpressure pocket and is configured to allow pressurized refrigerant in the discharge volume to be introduced into the backpressure pocket
Implementation Method 2
The second pressure pathway is located between the backpressure pocket and the intake volume and includes a dump valve for controllably bleeding off pressured refrigerant in the backpressure pocket into the intake volume
Implementation Method 3
The orbiting scroll and the fixed scroll form compression chambers for receiving the refrigerant from the intake volume and compressing the refrigerant as the drive shaft is rotated about the center axis
Data Source
AI summary
An electric compressor includes a housing, refrigerant inlet port, a refrigerant outlet port, an inverter section, a motor section, a compression device and a front cover. The housing defines an intake volume and a discharge volume. The refrigerant inlet port is coupled to the housing and is configured to introduce the refrigerant to the intake volume. The compression device is a scroll-type compression device configured to compress the refrigerant. The refrigerant outlet port is coupled to the housing and is configured to allow compressed refrigerant to exit the scroll-type electric compressor from the discharge volume. The electric compressor including a scroll backpressure system, located at least partially, within a compression device body.