Trochoid Oil Pump for Hermetic Compressor Lubrication
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Solution Overview
Problem
Centrifugal oil pumps in hermetic compressors face challenges in efficiently pumping oil during low-speed operations, leading to increased abrasion and reduced reliability due to insufficient lubrication of sliding parts, and the 'double-layer separation phenomenon' where refrigerant and oil separate, causing the pump to primarily suck refrigerant rather than oil.
Innovation Solution
A trochoid oil pump is introduced, which uses a trochoid gear coupled with the driving shaft to pump oil by varying volume, incorporating multiple suction holes that extend perpendicular to the surface to ensure consistent oil supply, even when oil and refrigerant separate, and adjustable suction hole configurations to manage mixed or separated refrigerant and oil states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a centrifugal oil pump is used to pump oil at high speeds, then the pump can efficiently pump oil using centrifugal force, but during low-speed operations the pump fails to pump oil effectively leading to insufficient lubrication
Solution Approach 1:
The patent replaces the centrifugal force-based mechanical pumping system with a trochoid gear mechanism that uses positive displacement and volume variation to pump oil. This substitution eliminates the speed-dependent centrifugal force mechanism and replaces it with a gear-driven volumetric pumping system that delivers consistent oil flow regardless of operating speed.
Solution Approach 2:
The patent changes the fundamental pumping parameter from centrifugal force (speed-dependent) to volumetric displacement (gear-driven). The trochoid gear mechanism varies the volume of oil captured in gear teeth spaces, creating a speed-independent pumping action that maintains reliable lubrication across all operating conditions.
2Quantity of substance
If the oil pump sucks from the bottom of the compressor casing, then it can access oil reservoir, but when refrigerant and oil separate into layers the pump primarily sucks refrigerant instead of oil
Solution Approach 1:
The patent applies local quality by creating a specific oil suction structure with multiple openings at different heights and positions on the pump housing. This localized multi-point suction system ensures that oil is drawn from various locations, preventing the pump from being misled by the refrigerant-oil interface and ensuring consistent oil supply regardless of separation conditions.
Solution Approach 2:
The patent segments the single suction opening into multiple openings positioned at different heights and locations on the pump housing. This segmentation allows the pump to draw oil from multiple zones simultaneously, ensuring that at least some openings remain in contact with the oil layer even when refrigerant-oil separation occurs, thereby maintaining reliable oil supply.
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 trochoid oil pump effectively lubricates compressor components at all operation speeds, preventing dry friction and ensuring reliable performance by consistently pumping oil, even during low-speed operations and when refrigerant and oil separate, thereby enhancing the compressor's reliability and efficiency.
Implementation Method 1
A trochoid gear (130) which performs a relative rotary motion so as to vary a volume thereof and pump the oil
Implementation Method 2
A trochoid gear (130) which performs a relative rotary motion so as to vary a volume thereof and pump the oil by being coupled with a driving shaft (4)
Data Source
AI summary
A hermetic compressor uses an oil pump that includes a trochoid gear. Therefore, regardless of the rotation speed of a driving motor of the compressor, a sufficient amount of oil can always be pumped. The oil pump unit may include a plurality of suction holes with openings at different heights. If the refrigerant and oil separate, at least one of the openings will admit oil into the oil pump unit, to ensure lubricating oil is supplied to the moving parts of the compressor.