Swing Arm Rib Segmentation for Casting Crack Prevention

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Solution Overview

Problem

The existing swing arm designs for two-wheeled sports vehicles require unnecessary thickness to prevent casting cracks, leading to increased weight and mold costs due to acute angles in the rib configuration.

Innovation Solution

The swing arm design features a rib connected to the pivot pipe at a location spaced from the connection between the outer wall and pivot pipe, eliminating acute angles and allowing for a hollow structure without additional thickness, thus reducing weight and mold complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the rib is connected to the pivot pipe at the same place as the outer wall part, then the casting structure is simple, but acute angles are formed causing cracks and requiring unnecessary thickness

Engineering Contradiction:

Improvecasting structure simplicityVSAvoidcrack prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The connection location of the rib to the pivot pipe is segmented from the connection location of the outer wall part to the pivot pipe. This spatial segmentation prevents the formation of acute angles at the same location, eliminating the root cause of casting cracks while maintaining manufacturing simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The problem is solved by transitioning from a two-dimensional planar connection (where all connections occur at the same location) to a three-dimensional spatial arrangement (where connections occur at different locations along the pivot pipe axis). This dimensional change eliminates acute angle formation without complicating the casting structure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If unnecessary thickness is added to secure casting thickness, then casting cracks are prevented, but the weight of the swing arm increases

Engineering Contradiction:

Improvecrack preventionVSAvoidswing arm weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The connection locations are preliminarily arranged at different positions before casting begins. This preliminary spatial arrangement prevents acute angle formation during the casting process itself, eliminating the need for compensatory thickness additions and thereby preventing unnecessary weight increase.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If the rib is connected at the same location as the outer wall, then the structure is compact, but acute angles cause casting defects

Engineering Contradiction:

Improvestructural compactnessVSAvoidcasting quality

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The rib connection is segmented from the outer wall connection location along the pivot pipe axis. This segmentation creates separate connection zones that avoid acute angle formation, ensuring high casting quality without significantly increasing structural complexity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9873478B2Swing arm

Publication Date: 2018.01.23 SUZUKI MOTOR CORP

AI summary

There is provided a swing arm configured to be coupled to a vehicle body frame to be vertically swingable via a pivot shaft. A main body has a pivot pipe in which the pivot shaft is to be inserted. A pair of right and left arm parts extend rearward from the main body. The main body is made by casting to have a hollow structure. The main body is provided with a rib configured to vertically partition an internal space thereof. The rib is connected to the pivot pipe at a place spaced from a connection place between the pivot pipe and an outer wall part defining an outer surface shape of the main body.