Compressor Unit Oil Level Balancing Through Rotation Speed Control

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Solution Overview

Problem

Compressor units with two compressors in parallel face challenges in oil level balancing, leading to unbalanced oil levels and potential oil loss, affecting normal operation.

Innovation Solution

A control method and device that alternately execute conventional operation steps and oil level adjustment steps, adjusting rotation speeds of compressors to balance oil levels without additional oil return pipelines, using a gas balance pipe and oil balance pipe for communication between compressors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an oil return pipeline device is added to balance oil levels between compressors, then oil level balance is improved, but device complexity and cost increase

Engineering Contradiction:
Improveoil level balanceVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the oil level balancing function from the mechanical oil return pipeline device and transfers it to the control system. The control device monitors oil levels and regulates compressor operation parameters (such as suction valve opening degree or injection quantity) to achieve oil level balancing without requiring additional physical oil return infrastructure, thereby reducing device complexity while maintaining reliability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical oil return pipeline system with a control-based regulation system. Instead of using physical oil return paths and mechanical components to balance oil levels, the system uses electronic sensors and control algorithms to monitor and adjust compressor parameters, substituting a mechanical solution with a control-based one that reduces structural complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If compressors operate simultaneously for a period of time, then productivity is improved, but oil level balance deteriorates

Engineering Contradiction:
ImproveproductivityVSAvoidoil level balance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention implements a feedback control mechanism where oil level sensors continuously monitor the oil levels in both compressors, and the control device receives this feedback information. Based on the feedback, the control device dynamically adjusts operation parameters such as suction valve opening degree or injection quantity to maintain oil level balance even when both compressors operate simultaneously for extended periods, thus preserving both productivity and reliability

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control device performs periodic oil level monitoring and adjustment cycles. During simultaneous compressor operation, the system periodically checks oil levels and makes necessary parameter adjustments at regular intervals, ensuring that oil level balance is maintained throughout the operation period without interrupting productivity

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP4641117A1Control method and control device for compressor unit
Publication Date: 2025.10.29 CARRIER CORP
  • EP4641117A1 patent drawingFigure 1
  • EP4641117A1 patent drawingFigure 2~3
  • EP4641117A1 patent drawingFigure 4~5

AI summary

The invention aims to provide a control method and a control device (200) for a compressor unit (100), in which oil levels of a first compressor (1) and a second compressor (2) can be adjusted without additionally arranging an oil return pipeline. A first aspect of this invention provides a control method for a compressor unit (100), the compressor unit (100) having a first compressor (1) and a second compressor (2), and the first compressor (1) and the second compressor (2) being in communication with each other through a gas balance pipe (3) and an oil balance pipe (4). The compressor unit (100) has a conventional operation step and an oil level adjustment step that are alternately executed, and in the oil level adjustment step, the compressor unit (100) changes a rotation speed of the first compressor (1) and/or the second compressor (2) to adjust oil levels of the first compressor (1) and the second compressor (2).