Engine Breather Oil Passage Segmentation

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Solution Overview

Problem

Existing engine designs with oil passages separate from the crankcase require precise machining, increasing costs and limiting the flexibility of the oil passage shape, as well as risking oil leakage.

Innovation Solution

An engine design featuring an oil passage defining member with a combination of integral and separate components within a breather device, allowing for flexible oil passage shapes while preventing leakage by routing oil back to the crankcase through a breather chamber and oil return hole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an oil passage is provided separate from the crankcase to improve shape flexibility, then the oil passage can have non-linear shapes, but the machining precision requirements increase and manufacturing cost increases

Engineering Contradiction:

Improveoil passage shape flexibilityVSAvoidmachining precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The oil passage is divided into two segments: a first oil passage formed integrally with the crankcase by casting, and a second oil passage formed separately by assembling an oil passage defining member. This segmentation allows the first portion to be manufactured with simple casting (high shape flexibility) while the second portion can be precisely machined (high precision) to connect to the transmission, thus resolving the contradiction between shape flexibility and machining precision requirements

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines two different manufacturing approaches (casting and separate machining) into a single oil passage system. The integrally-formed first oil passage and the separately-assembled second oil passage are merged to create a complete oil passage that achieves both shape flexibility (from casting) and precision (from machined connection), resolving the technical contradiction

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If an oil passage is provided separate from the crankcase to enhance shape flexibility, then the oil passage can be configured in complex shapes, but the manufacturing cost increases

Engineering Contradiction:

Improveoil passage shape flexibilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The oil passage system is segmented into a mass-produced integral portion (first oil passage) and a customized connection portion (second oil passage). This allows the majority of the oil passage to be manufactured through simple casting processes (low cost), while only the necessary connection sections require precise machining (higher cost), thus reducing overall manufacturing cost while maintaining shape flexibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different manufacturing qualities are applied to different portions of the oil passage: the main body uses simple casting (cost-effective) while the connection areas use precise machining (high quality). This local differentiation of manufacturing quality allows the system to achieve complex shapes without uniformly high manufacturing costs across the entire oil passage

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If an oil passage is made integral with the crankcase to reduce manufacturing cost, then the manufacturing process is simplified, but the oil passage shape is limited to linear forms

Engineering Contradiction:

Improvemanufacturing costVSAvoidoil passage shape flexibility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The oil passage is segmented into an integral casting portion (first oil passage) that provides cost-effective manufacturing, and a separate assembled portion (second oil passage) that enables complex non-linear shapes. This segmentation resolves the contradiction by allowing the inexpensive integral portion to handle straightforward routing while the flexible separate portion handles complex geometric requirements

Inventive Principle:

Principle #1Segmentation

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 reduces manufacturing costs and enhances oil passage flexibility, ensuring efficient lubrication without additional oil return components and minimizing leakage risks.

Implementation Method 1

the breather device being arranged to separate oil contained in blowby gas flowing into the enclosed space and return the separated oil to the crankcase

Methodology Applied

Scientific EffectGravitational settling: Gravitation

Data Source

PatentUS9546579B2Engine and straddle-type vehicle including the same

Publication Date: 2017.01.17 YAMAHA MOTOR CO LTD

AI summary

An engine 40 includes a breather device 20 and an oil passage defining member 30 disposed in the breather device 20. The breather device 20 includes a breather main body 22 integral with a crankcase 50, and a breather cover 24. The breather main body 22 and the breather cover 24 define an enclosed space 26 in communication with an inner space of the crankcase 50. The oil passage defining member 30 includes a first member 32 integral with the crankcase 50, and a second member 34. The first and second members 32 and 34 define an oil passage 38. The crankcase 50 includes a transmission chamber 60 in which a main shaft 72 and a drive shaft 74 are disposed, and oil feed holes 82A to 82C through which the oil passage 38 and the transmission chamber 60 are in communication with each other.