Scroll Compressor External Shell Heating for Lap-Tip Clearance Control

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Solution Overview

Problem

In scroll compressors with an outer-wall-less structure, pressure and heat cause the fixed and orbiting scrolls to bend and thermally expand, leading to potential seizing issues due to inadequate lap-tip clearance, which can result in refrigerant leakage and efficiency reduction.

Innovation Solution

A scroll compressor design that includes a heat source device to adjust the lap-tip clearance by heating or cooling the shell externally, allowing for dynamic adjustment of the clearance during operations to prevent contact and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the lap-tip clearance is set wide to prevent contact between scroll tips during operations, then the reliability is improved, but the refrigerant gas leaks more through the clearance causing efficiency reduction

Engineering Contradiction:

Improveprevention of lap-tip contactVSAvoidrefrigerant gas leakage

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies thermal expansion dynamics by heating the shell to expand it, which increases the lap-tip clearance dynamically during operations. This transforms a static clearance issue into a dynamic adjustment where the clearance expands with the shell, simultaneously preventing lap-tip contact while maintaining optimal refrigerant sealing to reduce leakage and energy loss.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the temperature parameter of the shell through heating. By increasing the shell temperature, thermal expansion occurs which increases the lap-tip clearance. This parameter change (temperature) directly affects the clearance dimension, allowing the system to achieve both reliability (contact prevention) and efficiency (reduced leakage) by optimizing the clearance through thermal control.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the lap-tip clearance is set narrow to reduce refrigerant gas leakage, then the efficiency is improved, but the scrolls may contact during operations due to thermal expansion and bending

Engineering Contradiction:

Improverefrigerant gas leakageVSAvoidprevention of lap-tip contact

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by proactively heating the shell before or during operations to induce thermal expansion that increases the lap-tip clearance. This preemptive action counteracts the potential harmful effect of thermal expansion and bending that would otherwise cause the scrolls to contact, thereby preventing reliability issues before they occur while maintaining narrow initial clearance for efficiency.

Inventive Principle:

Principle #9Preliminary anti-action

3Stability of the object's composition

If the frame includes an outer wall to support the fixed scroll, then the structural stability is improved, but the refrigerant suction space becomes narrow

Engineering Contradiction:

Improvestructural stability of frameVSAvoidrefrigerant suction space

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The patent extracts and removes the outer wall from the frame structure, transitioning to an outer-wall-less design. This extraction eliminates the space occupation by the outer wall, thereby enlarging the refrigerant suction space. The fixed scroll is alternatively supported by directly fixing to the inner wall of the shell or through other support mechanisms that do not require the outer wall, thus resolving the contradiction between structural stability and suction space volume.

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 adjustable lap-tip clearance maintains optimal performance by reducing refrigerant leakage while preventing contact between scroll tips, enhancing the compressor's efficiency and reliability.

Implementation Method 1

the pressure and heat generated during operations cause the fixed scroll and an orbiting scroll to bend and thermally expand

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the lap-tip clearance during operations may be adjusted by adjusting the temperature of the shell to cause the shell to expand or contract

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS11493046B2Scroll compressor

Publication Date: 2022.11.08 MITSUBISHI ELECTRIC CORP

AI summary

A scroll compressor includes a shell that is cylindrical, a fixed scroll fixed to an inner wall of the shell, an orbiting scroll that faces the fixed scroll, a frame fixed to the inner wall of the shell and that supports the orbiting scroll, and a heat source device provided on an outside of the shell and between the fixed scroll and the frame and configured to heat or cool the shell from the outside.