Boltless Twist-Lock Joint for Scroll Compressor Frame

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Solution Overview

Problem

Existing scroll compressor designs require fixed scroll bolts for assembly, increasing material costs, assembly time, and overall diameter due to the need for bolt holes and additional components, which complicates the manufacturing process and assembly.

Innovation Solution

A boltless connection is achieved by machining matching tapered radially contacting surfaces on the fixed scroll and frame, allowing them to twist together for secure locking, with a pressure dome clamping the scroll in place, eliminating the need for fixed scroll bolts and reducing the compressor's diameter, weight, and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fixed scroll bolts are used to attach the fixed scroll to the upper frame, then the connection strength and reliability are improved, but the overall diameter, weight, and manufacturing cost increase due to bolt holes and additional components

Engineering Contradiction:
Improveconnection strengthVSAvoidoverall diameter
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The patent removes the bolts entirely from the assembly, extracting the fastening function from separate components and integrating it into the twist-lock mechanism between the fixed scroll and frame. This eliminates the need for bolt holes and external fasteners, directly reducing the overall diameter while maintaining connection strength through the twisted interlocking surfaces.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the connection function into the structural components themselves. The fixed scroll and frame are designed with complementary tapered surfaces that, when twisted together, create an integrated lock. This combines the fastening function with the structural components, eliminating separate bolts and reducing part count, weight, and diameter.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If fixed scroll bolts are used to attach the fixed scroll to the upper frame, then the connection strength is improved, but the assembly time and manufacturing complexity increase due to drilling, tapping, and bolt installation

Engineering Contradiction:
Improveconnection strengthVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent extracts the fastening operation from multi-step processes (drilling, tapping, bolting) and replaces it with a single twist-lock action. The complementary tapered surfaces are pre-formed during manufacturing, and assembly requires only rotating the fixed scroll to engage the lock, dramatically reducing assembly time and manufacturing complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs the connection preparation in advance during manufacturing by forming the complementary tapered surfaces on the fixed scroll and frame. This preliminary action eliminates the need for on-site drilling and tapping, allowing rapid assembly through simple rotation and locking of the pre-prepared interfaces.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If fixed scroll bolts are used to attach the fixed scroll to the upper frame, then the connection reliability is improved, but the material cost and component quantity increase

Engineering Contradiction:
Improveconnection strengthVSAvoidcomponent quantity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the bolts and associated fastening components from the assembly. The connection function is extracted from separate fasteners and integrated into the twist-lock mechanism formed by the complementary tapered surfaces on the fixed scroll and frame, reducing component quantity and simplifying the device.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the fastening function into the structural components themselves. The fixed scroll and frame are designed with integrated tapered locking surfaces, combining the structural support and fastening functions into single components rather than requiring separate bolts and mounting features.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If fixed scroll bolts are used to attach the fixed scroll to the upper frame, then the connection strength is improved, but the weight of the compressor increases due to additional bolts and larger diameter requirements

Engineering Contradiction:
Improveconnection strengthVSAvoidcompressor weight
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent extracts the fastening mass from separate bolt components and eliminates it entirely. The connection is achieved through the twisted interlocking of the fixed scroll and frame themselves, removing the weight of multiple bolts, washers, and associated hardware while maintaining connection strength through the mechanical lock.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the fastening function into the existing structural mass of the fixed scroll and frame. Rather than adding separate fastening components, the connection strength is derived from the interlocked geometry of the components themselves, utilizing their existing mass and structure for both support and fastening functions.

Inventive Principle:
Principle #5Merging (Combining)

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 boltless design simplifies assembly, reduces material costs, and minimizes the radial footprint of the compressor, while maintaining secure locking during operation through discharge gas pressure, thus enhancing manufacturing efficiency and reducing component complexity.

Implementation Method 1

machining matching tapered radially contacting surfaces on each part which, when twisted together, pulls the fixed scroll axially toward the frame, locking it in place

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

when twisted together, pulls the fixed scroll axially toward the frame, locking it in place

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 3

discharge gas pressure acts on the dome to further clamp the fixed scroll in place with sufficient force

Methodology Applied
Scientific EffectPressure Increase: Pressure Increase

Implementation Method 4

discharge gas pressure acts on the dome to further clamp the fixed scroll in place

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP3998404B1Twist-lock, boltless fixed scroll-to-frame joint
Publication Date: 2024.10.23 TRANE INTERNATIONAL INC
  • EP3998404B1 patent drawingFigure 1
  • EP3998404B1 patent drawingFigure 2
  • EP3998404B1 patent drawingFigure 3

AI summary

A scroll compressor and methods of assembling the scroll compressor are disclosed. The scroll compressor includes a frame aligned about a longitudinal axis of the scroll compressor, the frame including a plurality of extensions extending radially from the longitudinal axis, the plurality of extensions including axially extending frame interlock mechanisms. A fixed scroll support is aligned about the longitudinal axis, the fixed scroll support including a plurality of extensions extending radially from the longitudinal axis, the plurality of extensions including axially extending fixed scroll support interlock mechanisms configured to engage the frame interlock mechanisms upon radial rotation. A fixed scroll wrap is integral with or attached to the fixed scroll support.