Rotary Compressor Oil Storage Layout for Low Refrigerant Charge

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Solution Overview

Problem

Conventional rotary compressors face challenges in maintaining sufficient refrigerant charge while using hydrocarbon refrigerants due to high miscibility with lubricating oil, leading to reduced efficiency and safety concerns.

Innovation Solution

A rotary compressor design with a specialized housing structure that includes an oil storage area between the cylinder end surface and bottom cover, reducing lubricating oil volume by 55%, while maintaining optimal refrigerant operation and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the compressor is filled with sufficient lubricating oil to ensure operational reliability, then the reliability is improved, but the refrigerant charge increases due to high miscibility between hydrocarbon refrigerant and lubricating oil

Engineering Contradiction:
Improveoperational reliabilityVSAvoidrefrigerant charge
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent divides the compressor internal space into distinct regions: an oil storage groove at the bottom for lubricating oil and a compression chamber above it for refrigerant compression. This spatial segmentation prevents mixing between the refrigerant and lubricating oil, allowing sufficient oil for reliability while minimizing refrigerant charge in the oil.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the lubricating oil into a separate storage groove located at the bottom of the compressor housing, isolating it from the main compression chamber. This extraction allows the system to maintain necessary oil levels for operational reliability while preventing excessive refrigerant dissolution in the oil, thus reducing overall refrigerant charge requirements.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If the compressor is filled with more lubricating oil to maintain oil level height, then the reliability is improved, but the operation efficiency decreases due to increased refrigerant dissolution in the oil

Engineering Contradiction:
Improveoperational reliabilityVSAvoidoperation efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

By segmenting the compressor into an oil storage groove and a compression chamber, the patent enables sufficient oil coverage for reliable operation while preventing refrigerant-oil mixing that would reduce operation efficiency. The groove structure ensures oil remains in the designated area without excessive refrigerant dissolution.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The oil storage groove acts as an intermediary structure that separates the lubricating oil from the refrigerant compression process. This intermediary allows the oil to perform its lubrication function for reliability while preventing it from absorbing excessive refrigerant that would harm operation efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Quantity of substance

If the lubricating oil volume is reduced to decrease refrigerant charge, then the refrigerant charge is reduced, but the operational reliability may be compromised

Engineering Contradiction:
Improverefrigerant chargeVSAvoidoperational reliability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent uses spatial segmentation with an oil storage groove to concentrate lubricating oil in a specific bottom region, ensuring sufficient oil volume for reliability while minimizing the overall refrigerant-oil interaction volume, thus reducing refrigerant charge requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

By extracting and isolating the lubricating oil into a separate groove, the patent reduces the volume of oil exposed to refrigerant, thereby decreasing refrigerant charge while maintaining adequate oil levels in the groove for operational reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If the compressor uses conventional housing structure without oil storage area, then the device complexity is lower, but the refrigerant-oil mixing increases leading to reduced safety and efficiency

Engineering Contradiction:
Improvehousing structure complexityVSAvoidrefrigerant-oil mixing
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an oil storage groove that segments the housing structure, creating a distinct oil storage region separate from the compression chamber. This simple segmentation effectively prevents refrigerant-oil mixing while adding minimal structural complexity to the housing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the lubricating oil into a dedicated storage groove within the housing, isolating it from the refrigerant compression space. This extraction prevents harmful refrigerant-oil mixing while requiring only a simple groove structure, thus maintaining low device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

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 design effectively reduces refrigerant-oil mixing, enhances safety, and improves energy efficiency by minimizing lubricating oil volume without compromising performance.

Implementation Method 1

At least one spring is located at each of the spring holes of the vane, so that the front end of the vane is in contact with the peripheral surface of the ring

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The basic working principle of the compressor is as follows: when the compressor is energized, the stator generates a magnetic field, which rotates the rotor, drives the crankshaft, and causes the rings to move eccentrically in the cylinder

Methodology Applied
Scientific EffectEccentric motion: Eccentric

Implementation Method 3

when the compressor is energized, the stator generates a magnetic field, which rotates the rotor, drives the crankshaft

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4692554A1Rotary compressor
Publication Date: 2026.02.11 RECHI PRECISION CO LTD
  • EP4692554A1 patent drawingFigure 1
  • EP4692554A1 patent drawingFigure 2
  • EP4692554A1 patent drawingFigure 3

AI summary

A rotary compressor includes a housing, a motor and a compression pump. The housing includes a main shell, a top cover and a bottom cover. The motor is located in the housing. The compression pump is located in the housing and below the motor. The compression pump includes a cylinder. The cylinder includes a first end surface and a second end surface, an oil storage area is formed between the second end surface of the cylinder of the compression pump and a bottom cover of the housing. Wherein a volume of the refrigerant oil in the oil storage area is V, an inner diameter of the main shell is M, a distance between a bottom surface of the bottom cover and a bottom surface of the cylinder of the compression pump is H, a circumference is π, and the following condition is satisfied: 25% ≤ V/(π(M/2)2H) ≤ 40%.