Magnetic Scroll Compressor Coupling for Torque Ripple Smoothing

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Solution Overview

Problem

Existing scroll compressors experience uneven torque curves and current ripples in the drive motor's supply line, leading to increased mechanical stress on the drive motor and bearing assembly, which affects durability and efficiency.

Innovation Solution

A scroll compressor design featuring a magnetic coupling between a stator and an orbiter, where a drive torque and a coupling torque act on the orbiter to smooth out torque fluctuations, reducing mechanical stress and current ripples by aligning torques in opposite directions during certain phases of the orbiter's movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional drive motor is used to drive the orbiter, then the orbiter can be driven, but uneven torque curves and current ripples occur leading to increased mechanical stress

Engineering Contradiction:
Improvedurability of drive motor and bearing assemblyVSAvoidmechanical stress and current ripple
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A coupling device with first and second coupling units is introduced as an intermediary between the drive motor and the orbiter. The coupling device includes magnetic coupling elements that generate a coupling torque to counteract uneven torque curves, smoothing the total torque applied to the orbiter while reducing current ripples in the drive motor's supply line.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The coupling device changes the torque parameter by generating a coupling torque that varies during the orbiter's movement. The coupling torque is adjusted to act against the drive torque during compression phases and in the same direction during expansion phases, thereby smoothing the total torque curve and reducing mechanical stress on the drive system.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a powerful drive motor is used to overcome torque fluctuations, then the orbiter can be driven reliably, but the compressor becomes heavier and more expensive

Engineering Contradiction:
Improveconsistent operation of scroll compressorVSAvoidweight of drive motor
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The coupling device acts as a torque-smoothing intermediary that allows the use of a less powerful drive motor. By generating a coupling torque that counteracts uneven torque curves, the system achieves reliable operation without requiring an oversized motor, thereby reducing the weight and cost of the drive system.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Power

If mechanical coupling is used between stator and orbiter, then torque can be transmitted, but wear occurs reducing durability

Engineering Contradiction:
Improvetorque transmissionVSAvoidwear resistance
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent replaces mechanical coupling with magnetic coupling. The coupling device uses magnetic coupling elements (permanent magnets or electromagnets) to transmit torque between the stator and orbiter without physical contact. This eliminates wear associated with mechanical coupling while maintaining effective torque transmission.

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

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 results in a more durable, quiet, and cost-effective scroll compressor with reduced mechanical stress on the drive motor and bearing assembly, allowing for a less powerful motor and improved operational efficiency.

Implementation Method 1

the first coupling unit is magnetically coupled to the second coupling unit and the second coupling unit introduces a coupling torque acting about the orbiter axis into the orbiter

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Implementation Method 2

the first coupling unit or the second coupling unit comprises at least one laminated core with at least two layers of a ferromagnetic material arranged side by side in a stack. The layers are arranged axially relative to each other. This design has the advantage that only small eddy currents are generated in the laminated core during operation of the scroll compressor, thus preventing overheating of the coupling unit and the laminated core.

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Data Source

PatentEP4326989B1Scroll compressor and method for operating the scroll compressor
Publication Date: 2025.12.31 ROBERT BOSCH GMBH
  • EP4326989B1 patent drawingFigure 1
  • EP4326989B1 patent drawingFigure 2~3
  • EP4326989B1 patent drawingFigure 4~5

AI summary

The invention relates to a scroll compressor (10) and to a method for operating the scroll compressor (10). The scroll compressor (10) has a stator (15), an orbiter (20) which can be moved about an orbiter axis (55) relative to the stator (15), and a coupling device (50). The stator (15) and the orbiter (20) engage into each other and at least partly delimit at least one working area (105) for compressing a fluid (110) which can be filled into the working area (105). The coupling device (50) has a first coupling unit (60) which is arranged on the stator (15) and a second coupling unit (65) which is arranged on the orbiter (20) opposite the first coupling unit (60), wherein the first coupling unit (60) is magnetically coupled to the second coupling unit (65), and the second coupling unit (65) introduces a coupling torque (MK) which acts about the orbiter axis (55) into the orbiter (20).