Scroll Compressor Radial Compliance for Stable Involute Contact

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Solution Overview

Problem

Variable speed scroll compressors face challenges in maintaining constant involute wall contact and optimal compression performance across different operating conditions and speeds, due to bending of the main shaft under high loads and centrifugal forces.

Innovation Solution

The implementation of a scroll compressor design with dynamic radial compliance, utilizing a compliant counterweight and counterweight guide plate to maintain constant involute wall contact, offsetting the centrifugal force of the orbiting scroll and stabilizing the slider block, thereby optimizing flank contact force across varying speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If variable speed operation is implemented to improve energy efficiency and adaptability, then the compressor can operate across different cooling loads, but the main shaft bends under high loads and centrifugal forces causing loss of involute wall contact

Engineering Contradiction:

Improvevariable speed operationVSAvoidinvolute wall contact

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

A counterweight is added to the crankshaft that generates centrifugal force opposite to the orbiting scroll, balancing the radial forces acting on the main shaft. This prevents shaft bending and maintains the eccentricity required for involute wall contact during variable speed operation.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent introduces dynamic radial compliance through a compliant counterweight and counterweight guide plate assembly that allows the eccentricity to self-adjust during operation. This dynamic adjustment maintains optimal flank contact force across varying speeds by compensating for shaft deflection in real-time.

Inventive Principle:

Principle #15Dynamics

2Productivity

If high compression ratios are achieved through increased shaft eccentricity, then compression performance improves, but centrifugal forces increase causing shaft bending and loss of contact

Engineering Contradiction:

Improvecompression performanceVSAvoidcentrifugal force

Core Design Contradiction:

ProductivityVSForce

Solution Approach 1:

The counterweight is designed to generate centrifugal force that directly opposes the force from the orbiting scroll, balancing the radial loads on the main shaft. This allows high compression ratios to be achieved without shaft bending, as the counterweight compensates for the increased centrifugal forces.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent employs dynamic radial compliance that allows the shaft eccentricity parameters to self-adjust during operation. The compliant counterweight guide plate assembly enables the eccentricity to adapt to varying operating conditions, maintaining optimal flank contact force while accommodating high compression ratios without excessive shaft bending.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If rigid shaft design is used to maintain structural integrity, then manufacturing is simpler, but the shaft bends under load causing noise and leakage

Engineering Contradiction:

Improveshaft designVSAvoidnoise and leakage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

By adding the counterweight to balance centrifugal forces, the patent eliminates shaft bending in rigid shaft designs. This allows the use of simpler rigid shaft construction while preventing the harmful effects of noise and leakage that would otherwise result from loss of involute wall contact.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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

This design ensures constant involute flank contact from low to high speeds, reducing noise and leakage, and maintaining optimal compression performance by balancing the centrifugal forces and stabilizing the orbiting scroll bearing.

Implementation Method 1

offsetting the centrifugal force of the orbiting scroll and stabilizing the slider block

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS11542942B2Dynamic radial compliance in scroll compressors

Publication Date: 2023.01.03 HITACHI JOHNSON CONTROLS AIR CONDITIONING INC

AI summary

In some examples, a scroll compressor may include an orbiting scroll and a fixed scroll having spiral involutes intermeshed together. A slider block may be disposed on the eccentric portion of a main shaft and the slider block may be attached to a compliant counterweight. The counterweight may be supported by a counterweight guide plate that is supported by the main shaft. The counterweight guide plate may also have an arm securing a top portion of the counterweight thereby securing the slider block. In some implementations, a spring assembly may be provided between an outer edge of the counterweight and the counterweight guide plate. These components may, in part, allow for a constant involute contact between the fixed scroll and orbiting scroll involutes at high speeds thereby achieving high compression efficiency.