Scroll Compressor Hydrostatic Lower Bearing Arrangement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional scroll compressors experience inefficiency and reduced lifetime due to insufficient lubrication at high rotational speeds, leading to high friction losses and wear at the lower axial thrust bearing.
Innovation Solution
Incorporating a pressurized oil chamber connected to the oil pump, which generates hydrodynamic pressure to counteract gravitational forces, improving lubrication and reducing friction at the axial thrust bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scroll compressor operates at high rotational speed, then productivity is improved, but the lower axial thrust bearing experiences insufficient lubrication leading to high friction losses and wear
Solution Approach 1:
The patent introduces a hydrostatic lubrication system using pressurized oil supplied to the lower axial thrust bearing. The oil pump delivers pressurized lubricant through supply channels to the bearing surfaces, creating a hydrostatic film that separates the bearing surfaces and reduces friction. This hydraulic approach ensures reliable lubrication even at high rotational speeds where conventional hydrodynamic lubrication becomes insufficient.
Solution Approach 2:
The patent changes the lubrication parameter from relying solely on hydrodynamic effects (speed-dependent) to hydrostatic effects (pressure-dependent). By introducing a pressurized oil supply system, the lubrication regime is transformed to maintain adequate film thickness and reduce friction losses regardless of rotational speed variations.
2Productivity
If the scroll compressor operates at high rotational speed, then productivity is improved, but friction losses at the lower axial thrust bearing increase due to gravitational force
Solution Approach 1:
The hydrostatic lubrication system uses pressurized oil to create a lubricating film between the bearing surfaces. The pressure-generated oil film counteracts the gravitational force acting on the drive shaft and reduces direct metal-to-metal contact, thereby minimizing friction losses and energy consumption at the lower axial thrust bearing during high-speed operation.
Solution Approach 2:
The pressurized oil film acts as a counterbalancing force against the gravitational load on the drive shaft. The hydrostatic pressure generated in the lubricant film provides an upward force that counteracts the weight of the rotating components, reducing the effective load on the bearing and consequently lowering friction losses.
3Device complexity
If conventional lower bearing arrangement is used, then device complexity is low, but wear of thrust bearing surfaces reduces lifetime
Solution Approach 1:
The patent incorporates a hydrostatic lubrication system with oil supply channels and pressurized lubricant delivery to the lower axial thrust bearing. This additional hydraulic infrastructure, while increasing device complexity, ensures continuous film formation and reduced wear on bearing surfaces, thereby extending compressor operational lifetime.
Solution Approach 2:
The oil supply channels are pre-configured within the bearing housing to deliver lubricant to critical bearing surfaces before contact occurs. This preliminary lubrication action ensures that the bearing surfaces are always separated by an oil film, preventing wear and extending component life.
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
Enhances compressor efficiency and extends the lifespan by reducing frictional losses and wear on thrust bearing surfaces.
Implementation Method 1
a pressurized oil chamber which is fluidly connected to the oil pump, the pressurized oil chamber being at least partially delimited by the outer surface of the lower end portion of the drive shaft, the inner radial bearing surface and the upper and lower axial thrust bearings
Implementation Method 2
Such a configuration of the lower bearing arrangement, and particularly the provision of the pressurized oil chamber, leads to significant hydrodynamic pressure in the pressurized oil chamber when the scroll compressor operates at high rotational speed. Such a significant hydrodynamic pressure generate hydrostatic forces at the upper and lower axial thrust bearings
Implementation Method 3
an oil pump arranged at a lower end of the drive shaft and immersed in an oil sump arranged in a bottom section of the hermetic outer shell, the oil pump being configured to deliver, during operation of the scroll compressor, oil to the compression unit and to the upper and lower bearing arrangements
Data Source
AI summary
The scroll compressor includes a compression unit; a drive shaft which is vertically orientated; a lower bearing arrangement (28) configured to rotatably support the drive shaft; and an oil pump (29) arranged at a lower end of the drive shaft and configured to deliver oil to the compression unit and to the lower bearing arrangement (28). The lower bearing arrangement (28) comprises a radial bearing housing (34) including an inner radial bearing surface (37) surrounding the lower end portion of the drive shaft; upper and lower axial thrust bearings (43, 44) configured to limit an axial movement of the drive shaft; and a pressurized oil chamber (51) fluidly connected to the oil pump (29), the pressurized oil chamber (51) being at least partially delimited by the outer surface of the lower end portion of the drive shaft, the inner radial bearing surface (37) and the upper and lower axial thrust bearings (43, 44).