Scroll Compressor Back Pressure Chamber and Oil Throttle Design
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Solution Overview
Problem
In motor-driven scroll type compressors, the lack of a back pressure chamber and throttle in the oil supply passage leads to excessive pressure leakage, compromising the function of the back pressure chamber and reducing lubrication to remote bearings, which affects compressor durability and performance.
Innovation Solution
A motor-driven scroll type compressor design that includes a back pressure chamber and an oil supply passage with a first throttle, where the lubricating oil is supplied from an oil reserve chamber to remote bearings without affecting the back pressure chamber's function, using a combination of clearances and strategically placed throttles to maintain appropriate pressure and lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back pressure chamber is added to the compressor, then the compression unit can function properly to compress refrigerant gas, but the structure becomes more complex and requires additional components
Solution Approach 1:
The back pressure chamber is merged with the discharge chamber by forming a partition wall that divides the discharge chamber into a compression chamber and a back pressure chamber. This integration allows the back pressure chamber to function without requiring a completely separate structure, thus improving reliability while controlling complexity.
Solution Approach 2:
The discharge chamber is segmented into two functional regions: a compression chamber for compressing refrigerant gas and a back pressure chamber for maintaining pressure. This segmentation allows each region to perform its specific function optimally while being part of an integrated structure.
2Reliability
If a throttle is added to the oil supply passage, then lubricating oil can be supplied stably to remote bearings without affecting back pressure chamber function, but the device complexity increases
Solution Approach 1:
A throttle is added locally at the oil supply passage leading to the remote bearing, rather than modifying the entire oil supply system. This localized modification allows stable lubrication delivery to the specific bearing location without affecting the overall system complexity significantly.
Solution Approach 2:
The throttle acts as an intermediary component in the oil supply passage, regulating oil flow pressure and quantity to ensure stable lubrication reaches the remote bearing. This intermediary element solves the lubrication problem without requiring complex system-wide changes.
3Device complexity
If no throttle is provided in the oil supply passage, then the structure is simpler, but pressure leaks excessively through the oil supply passage causing the back pressure chamber to fail
Solution Approach 1:
A throttle is introduced locally in the oil supply passage to control pressure, preventing excessive pressure leakage. This localized addition maintains the overall simplicity of the structure while ensuring the back pressure chamber functions reliably.
4Quantity of substance
If lubricating oil is separated and reserved in the oil reserve chamber, then the oil rate in refrigerant gas is reduced, but the supply of lubricating oil to remote bearings deteriorates
Solution Approach 1:
The oil reserve chamber acts as an intermediary storage location for separated lubricating oil. A throttle in the oil supply passage regulates the flow from the oil reserve chamber to ensure adequate lubrication reaches remote bearings, balancing oil separation benefits with lubrication requirements.
Solution Approach 2:
The throttle modifies the flow parameters (pressure and flow rate) of lubricating oil from the oil reserve chamber, transforming the oil flow to ensure sufficient lubrication reaches remote bearings even after oil separation has reduced the overall oil rate in the refrigerant gas.
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 design ensures stable lubrication to remote bearings, maintains the functionality of the back pressure chamber, and enhances compressor durability and efficiency, while simplifying the structure and reducing production costs.
Implementation Method 1
a first throttle (77) in the oil supply passage (70) of the rotary shaft (24)
Implementation Method 2
the clearance (36) and a first throttle (77) in the oil supply passage (70)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A motor-driven scroll type compressor (1) has a motor (40) that includes a rotary shaft (24) and rotates the rotary shaft, a bearing (25) for rotatably supporting front end (24A) of the rotary shaft, a fixed scroll member (16), a movable scroll member (22) driven by rear end (24B) of the rotary shaft, compression chambers (38) defined by the movable scroll member and the fixed scroll member and a housing (10). The rotation of the rotary shaft makes an orbital motion of the movable scroll member around the axis of the rotary shaft and accordingly the compression chambers are moved radially and inwardly thereby to compress the refrigerant gas. The compressor further has a suction chamber (41) communicating with the compression chambers, a discharge chamber (47), an oil separation chamber (51) separating lubricating oil from the refrigerant gas and communicating with the discharge chamber and a back pressure chamber (39) provided in front of the movable scroll member in the housing and facing to the rear end of the rotary shaft. The back pressure chamber communicates with the oil separation chamber. The rotary shaft includes a first opening (71) at a position adjacent to the front end of the rotary shaft and facing an inner surface of the bearing, a second opening (72) at a position adjacent to the rear end of the rotary shaft and communicating with the back pressure chamber, a communication passage (73) interconnecting the first opening and the second opening and a throttle (77) formed by a clearance between the first opening and the inner surface of the bearing.