Electric Scroll Compressor Backpressure Control for Low Friction
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Solution Overview
Problem
Electric compressors in battery-powered vehicles face challenges with high-speed operation leading to noise and efficiency loss due to improper backpressure, which can cause oil film loss and excess friction between scrolls.
Innovation Solution
A scroll compressor with a backpressure system that includes a first pressure pathway to introduce pressurized refrigerant into a backpressure pocket and a second pathway with a dump valve to control refrigerant flow, maintaining a fixed pressure differential and reducing excess friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backpressure is increased to prevent scroll separation, then sealing is improved, but friction increases and efficiency decreases
Solution Approach 1:
A dump valve is introduced as an intermediary component between the backpressure pocket and the atmosphere. This valve mediates the backpressure by selectively releasing excess pressure when the orbiting scroll separates from the fixed scroll, thereby maintaining reliable sealing during normal operation while preventing excessive friction and energy loss during separation events.
2Productivity
If compressor speed is increased to improve productivity, then cooling capacity increases, but noise increases
Solution Approach 1:
The dump valve creates a feedback mechanism that responds to scroll separation conditions. When the orbiting scroll separates from the fixed scroll, the backpressure increases and triggers the dump valve to open, releasing pressure. This feedback loop actively dampens vibrations and noise generated during separation, allowing the compressor to operate at high speeds with reduced noise levels.
3Reliability
If backpressure is increased to maintain scroll contact, then sealing is improved, but oil film is lost
Solution Approach 1:
The dump valve acts as an intermediary that releases excess backpressure when it reaches levels that would cause oil film breakdown. By controlling the maximum backpressure through this valve, the system maintains sufficient contact pressure for sealing while preventing the excessive pressure that would strip the protective oil film from the scroll surfaces.
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 efficiency and reduces noise by controlling backpressure, minimizing friction, and extending the compressor's operating life.
Implementation Method 1
a first pressure pathway 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
a second pressure pathway between the backpressure pocket and the intake volume, the second pressure pathway including a dump valve for controllably bleeding off pressured refrigerant in the backpressure pocket into the intake volume
Implementation Method 3
an orbiting scroll and a fixed scroll forming compression chambers for receiving the refrigerant from the intake volume and compressing the refrigerant
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An electric (10) compressor includes a housing (12), refrigerant inlet port (68), a refrigerant outlet port (70), an inverter section (44), a motor section (54), a compression device (18) and a front cover (28). The housing defines an intake volume (74) and a discharge volume (82). The refrigerant inlet port (68) 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 (70) is coupled to the housing and is configured to allow compressed refrigerant to exit the scroll-type electric compressor from the discharge volume (82). The electric compressor including a scroll backpressure system (200), located at least partially, within a compression device body (202).