Compressor Bolt Spacer for Scroll-Chamber Frame Stability

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Solution Overview

Problem

In turbochargers, impeller breakage can generate tensile stress in bolts fastening the scroll-chamber frame and adjacent frames, leading to potential bolt breakage and instability in the joint state between these frames.

Innovation Solution

The introduction of a spacer between the head portion of the bolt and the scroll-chamber frame, or the use of a clamp to nip the frames, increases the shank length of the bolt or applies a pressing force to prevent bolt breakage due to tensile stress caused by impeller fragments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a bolt is used to fasten the scroll-chamber frame and the first frame, then the frames are joined together, but the bolt may break due to tensile stress from impeller fragments

Engineering Contradiction:
Improvebolt strengthVSAvoidjoint stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

A spacer is introduced as an intermediary component between the bolt head and the scroll-chamber frame. This spacer extends the bolt's shank length, providing additional engagement length and distributing the tensile stress from impeller fragments over a longer distance, thereby preventing bolt breakage while maintaining joint stability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The spacer acts as a cushioning element that is pre-installed between the bolt head and the frame. When impeller fragments cause sudden tensile stress, the extended shank length provided by the spacer absorbs and distributes the shock load, preventing the bolt from breaking under unexpected impact forces

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Strength

If the bolt shank length is increased to prevent breakage, then the bolt can withstand tensile stress, but the device complexity increases

Engineering Contradiction:
Improvebolt tensile resistanceVSAvoidfastening structure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The fastening system is segmented into distinct functional components: the bolt, the spacer, and the frames. By separating the stress-absorbing function into a dedicated spacer component, the bolt itself can remain a standard length while the system as a whole achieves the required tensile resistance, avoiding the need for an overly long complex bolt

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spacer serves as a simple intermediary element that adds functional capability (stress distribution) without significant complexity. It is a basic mechanical component that can be easily manufactured and installed, providing the needed shank extension while maintaining overall system simplicity

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3009633B1Compressor and supercharger
Publication Date: 2020.02.05 MITSUBISHI HEAVY IND LTD
  • EP3009633B1 patent drawingFigure 1
  • EP3009633B1 patent drawingFigure 2
  • EP3009633B1 patent drawingFigure 3~4

AI summary

An object of the present invention is to provide a compressor and a turbocharger whereby it is possible to suppress breakage of a bolt fastening a frame adjacent to a scroll-chamber frame and the scroll-chamber frame effectively and to join the frames stably. A compressor 10 includes: an impeller 14 for compressing air; an air-guide cylinder 16 for housing the impeller 14 and guiding the air; a scroll-chamber frame 20 disposed adjacent to the air-guide cylinder16, the scroll-chamber frame 20 forming a scroll chamber 18 for guiding the air having passed through the air-guide cylinder 16 to outside; a frame (22, 40) disposed adjacent to the scroll-chamber frame 20; a bolt (25, 48) for fastening the scroll-chamber frame 20 and the frame (22, 40); and a spacer 28 disposed between a head portion (26, 52) of the bolt (25, 48) and the scroll-chamber frame 20.