Welded Aluminum Engine Block Joining

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Solution Overview

Problem

Small air-cooled internal combustion engines face issues with leaks, thermal expansion, and material distortion due to bolted connections between the cylinder block and cylinder head, leading to inefficiencies in heat transfer and increased oil consumption.

Innovation Solution

Implementing a welded connection between the aluminum cylinder block and cylinder head, utilizing advanced aluminum die-casting techniques to reduce gas porosity and allow for effective welding, eliminating the need for head and crankcase gaskets and reducing material mass at connection points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If bolted connections are used between cylinder block and cylinder head, then assembly and disassembly are easier, but leaks and thermal expansion occur leading to reduced reliability

Engineering Contradiction:

Improveassembly easeVSAvoidconnection reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the mechanical bolted connection system with a welding system. Instead of using bolts and gaskets to join the cylinder block and cylinder head, the invention uses welding to create a permanent, leak-proof connection. This substitution eliminates the problems of thermal expansion, distortion, and leakage associated with bolted connections while maintaining assembly feasibility through pre-positioned guide pins and alignment features.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If gaskets are used at head and crankcase connections, then sealing is achieved, but material mass increases and heat transfer efficiency decreases

Engineering Contradiction:

Improvesealing effectivenessVSAvoidconnection mass

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent extracts and eliminates the gasket component from the connection system. By using welding to join the cylinder block to the cylinder head and the crankcase to the engine block, the invention removes the need for gaskets entirely. This extraction reduces material mass at connection points and eliminates the thermal barrier that gaskets create, thereby improving heat transfer efficiency while maintaining sealing effectiveness through the metallurgical bond of welding.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of manufacture

If traditional aluminum die-casting is used, then manufacturing is easier, but gas porosity prevents effective welding

Engineering Contradiction:

Improvecasting easeVSAvoidgas porosity level

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the parameters of the aluminum die-casting process to produce metal with suitable welding properties. This involves modifying casting parameters such as temperature, pressure, and cooling rates to minimize gas porosity and produce dense, homogeneous aluminum alloy structures. The invention specifies using aluminum alloys with controlled composition and properties that are optimized for both casting and subsequent welding operations, thereby achieving both ease of manufacture and welding suitability.

Inventive Principle:

Principle #35Parameter changes

4Ease of repair

If bolted connections are used, then disassembly for maintenance is easier, but thermal distortion and leaks increase oil consumption

Engineering Contradiction:

Improvedisassembly easeVSAvoidoil consumption

Core Design Contradiction:

Ease of repairVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical bolted connection system with a welded connection system, which eliminates thermal distortion and leakage issues that lead to increased oil consumption. While welded connections are permanent, the invention incorporates design features such as removable valve covers and accessible push rod tubes that allow for maintenance without requiring disassembly of the main welded joints. This approach prioritizes preventing oil loss through improved sealing and thermal management over ease of disassembly.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution reduces oil consumption, improves heat transfer, minimizes material usage, and enhances engine performance by eliminating leak points and thermal distortion, resulting in a more efficient and cost-effective engine design.

Implementation Method 1

an aluminum push rod tube separate from and press fit between the aluminum cylinder block and the aluminum cylinder head

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS10202938B2Welded engine block for small internal combustion engines

Publication Date: 2019.02.12 BRIGGS & STRATTON CORP

AI summary

A small air-cooled internal combustion engine includes an aluminum cylinder block at least partially defining an aluminum cylinder bore, an aluminum cylinder head attached to the aluminum cylinder block, and an aluminum push rod tube separate from and press fit between the aluminum cylinder block and the aluminum cylinder head. The aluminum push rod tube includes a cylinder block end portion, a cylinder head end portion, and a main body extending between the cylinder block end portion and the cylinder head end portion.