Connecting Rod Width Reduction for Long Stroke Engines

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Solution Overview

Problem

The existing manufacturing methods for connecting rods in internal combustion engines are not adaptable for long stroke configurations, leading to interference issues during assembly, increased costs, and reduced productivity due to the need for new manufacturing facilities and potential fretting wear and deformation at the mating surfaces.

Innovation Solution

A method that involves pre-machining and cutting the connecting rod and bearing cap to reduce their widths to match the cylinder bore diameter, creating a step-free surface and allowing the same jigs to be used for both existing and long stroke engines, thereby avoiding interference and maintaining the same clamping reference points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional partitioning methods (horizontal or slant) are used for connecting rod manufacturing, then the manufacturing process is simple and existing facilities can be used, but the connecting rod width interferes with long stroke engine cylinder bores during assembly

Engineering Contradiction:

Improveadaptability to long stroke engine configurationsVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by performing width reduction machining on the connecting rod and bearing cap before final assembly. The upset portions are machined down to create a step-free surface that allows the connecting rod to pass through the cylinder bore without interference, enabling long stroke engine configurations while using conventional manufacturing facilities.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If the connecting rod width is reduced to fit long stroke engines, then adaptability to long stroke configurations is improved, but new manufacturing facilities and processes are required increasing cost and reducing productivity

Engineering Contradiction:

Improveadaptability to long stroke engine configurationsVSAvoidmanufacturing productivity

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent achieves universality by designing a connecting rod with upset portions that can be machined to different width specifications. The same basic connecting rod design and manufacturing process can serve both conventional engines and long stroke engines, eliminating the need for dedicated facilities for long stroke production and maintaining high productivity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the connecting rod width is reduced for long stroke engines, then interference with cylinder bore is avoided, but manufacturing costs increase due to new facilities and processes

Engineering Contradiction:

Improveadaptability to long stroke engine configurationsVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by machining only the upset portions of the connecting rod and bearing cap to reduce width, rather than redesigning the entire component. This localized modification allows the connecting rod to fit long stroke engines while maintaining the original design for the majority of the structure, minimizing manufacturing cost increases.

Inventive Principle:

Principle #3Local quality

4Ease of manufacture

If conventional connecting rod design is used, then manufacturing is simpler and costs are lower, but fretting wear and deformation occur at mating surfaces during assembly

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidresistance to fretting wear and deformation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by creating a step-free surface through width reduction machining before assembly. This preliminary modification eliminates the stepped configuration that causes stress concentration and fretting wear at mating surfaces, improving reliability without complicating the manufacturing process.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9784304B2Connecting rod for an engine and method of making thereof

Publication Date: 2017.10.10 NISSAN MOTOR CO LTD

AI summary

A method to modify the geometry of a connecting rod of an internal combustion engine includes providing a connecting rod having a crankshaft bore at a first end, wherein the first end has a bearing cap and a bottom end portion of the connecting rod, mating the bearing cap with the bottom end portion of the connecting rod to form the crankshaft bore of the connecting rod, machining a width upset portion of the bottom end portion to reduce a width of the bottom end portion of the connecting rod, machining a width upset portion of the bearing cap to reduce a portion of a width of the bearing cap, and reducing the width of the bottom end portion of the connecting rod and the portion of the width of the bearing cap to a width smaller than a cylinder bore of the internal combustion engine.