Scroll Compressor Back Pressure Chamber Refrigerant Trapping
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Solution Overview
Problem
In scroll compressors, the challenge lies in maintaining efficient operation by preventing refrigerant from being trapped in the back pressure chamber during shutdown, which leads to high initial torque requirements and increased noise and abrasion when restarting, due to the difficulty in discharging refrigerant from the back pressure chamber to the suction side.
Innovation Solution
The design incorporates a switching device with a recessed surface and a flow restrictor to reduce contact area and prevent refrigerant flow into the discharge pressure apply hole, allowing the switching device to move freely and ensuring quick re-operation by maintaining equilibrium pressure in the back pressure chamber during shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the end of the wrap and the surface of the head plate are strongly attached to each other, then leakage is prevented, but friction increases, increasing damage due to noise and abrasion
Solution Approach 1:
The patent applies different attachment strengths to different regions of the wrap-end-to-head-plate interface. The wrap end is designed to be closely attached to the head plate at the peripheral region for effective sealing, while the central region maintains a controlled gap. This local differentiation allows the system to achieve reliable sealing at the edges without excessive friction across the entire contact surface.
2Object-affected harmful factors
If adhesion strength is low, then friction is reduced, however, sealing force decreases, increasing leakage
Solution Approach 1:
The contact interface between the wrap end and head plate is segmented into two functional zones: a peripheral sealing zone with strong attachment for preventing leakage, and a central operating zone with reduced attachment for minimizing friction. This segmentation allows each zone to optimize its performance independently without compromising the other.
3Device complexity
If the back pressure chamber is formed on the bottom surface of the orbiting scroll, then the structure is simple and bypass hole formation is easy, but the back pressure chamber changes configuration and position according to orbiting motion, causing tilt, vibration and noise
Solution Approach 1:
The patent extracts the back pressure chamber from the moving orbiting scroll and relocates it to the stationary head plate. This extraction removes the back pressure chamber from the orbiting motion, eliminating the configuration changes and positional variations that cause tilt, vibration, and noise, while maintaining structural simplicity.
4Stability of the object's composition
If the back pressure chamber is formed on the top surface of the fixed scroll, then the configuration and position are fixed, preventing tilt and improving sealing, but the structure becomes more complicated
Solution Approach 1:
The patent merges the back pressure chamber with the head plate structure, combining two previously separate components (back pressure chamber and head plate) into a unified structure. This integration maintains the configuration stability and anti-tilt benefits while reducing overall structural complexity by eliminating the need for separate back pressure chamber components.
5Reliability
If refrigerant is trapped in the back pressure chamber during shutdown, then high initial torque is required for restart, but the switching device cannot discharge refrigerant to the suction side
Solution Approach 1:
The patent introduces an intermediate discharge hole as a mediator between the back pressure chamber and the suction side. This intermediate pathway allows refrigerant to be gradually discharged from the back pressure chamber to the suction side during shutdown, preventing pressure buildup that would otherwise require high initial torque for restart, while maintaining reliable restart capability.
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
This solution enables the scroll compressor to quickly re-start with reduced noise and abrasion, improving operational efficiency by ensuring proper discharge of refrigerant and maintaining equilibrium pressure in the back pressure chamber.
Implementation Method 1
a back pressure chamber having an intermediate pressure, which is defined as a value between a discharge pressure and a suction pressure, may be formed in or at a back surface of the orbiting scroll or the fixed scroll
Implementation Method 2
The orbiting scroll revolves with respect to the fixed scroll, thereby reducing a volume of a compression chamber, which is formed between the fixed scroll and the orbiting scroll according to an orbiting motion of the orbiting scroll, thus increasing a pressure of a fluid
Data Source
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AI summary
A scroll compressor is provided that may include a casing including a rotational shaft, a cover fixed inside of the casing to partition the inside of the casing into a suction space and a discharge space, a first scroll revolved by rotation of the rotational shaft, a second scroll disposed on or at one side of the first scroll to define a compression chamber together with the first scroll, the second scroll including a discharge, through which a refrigerant pressed in the compression chamber may be discharged, a switching device movably disposed on or at one side of the discharge to selectively open and close the discharge, a back pressure portion including a moving guide that accommodates at least a portion of the switching device, and a top surface that covers one side of the switching device; and an adhesion preventer that reduces a contact area between the switching device and at least a portion of the back pressure portion.