Engine Cylinder Bolt Shortening via Piston Ring Inversion

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Solution Overview

Problem

The existing engine designs require longer bolts to connect the head cylinder, body cylinder, and crankcase, leading to increased weight due to the longer distance between these components, which is inefficient and heavy.

Innovation Solution

The engine design includes a piston ring that abuts on a lower section within the crankcase when at bottom dead center, allowing for a shorter distance between the head cylinder and crankcase, thus reducing the length of the cylinder fixing bolts and overall engine weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the piston ring is positioned higher than the crankcase (conventional design), then the piston can complete its full stroke, but the distance between the head cylinder and crankcase increases, requiring longer bolts and increasing engine weight

Engineering Contradiction:

Improvepiston stroke completionVSAvoidengine weight

Core Design Contradiction:

Ease of operationVSWeight of moving object

Solution Approach 1:

The patent inverts the conventional arrangement by positioning the piston ring below the crankcase at bottom dead center instead of above it. This inversion allows the piston to complete its full stroke while reducing the distance between the head cylinder and crankcase, thereby shortening the bolt length and reducing engine weight.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the vertical dimension of the piston ring position relative to the crankcase. By moving the piston ring from a higher position (conventional) to a lower position (below crankcase), the overall height of the engine assembly is reduced, allowing shorter connecting bolts and reducing engine weight.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If longer bolts are used to connect the head cylinder, body cylinder, and crankcase, then the components can be properly secured, but the engine weight increases

Engineering Contradiction:

Improvecomponent connection strengthVSAvoidengine weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the key parameter of bolt length by repositioning the piston ring. This parameter change allows the use of shorter bolts while maintaining adequate connection strength, as the reduced distance between head cylinder and crankcase provides sufficient engagement length for the shortened bolts.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the upper section of the body cylinder is made longer to accommodate the piston stroke, then the piston can reach bottom dead center, but the distance between head cylinder and crankcase increases, requiring longer bolts

Engineering Contradiction:

Improvepiston bottom dead center reachVSAvoiddistance between head cylinder and crankcase

Core Design Contradiction:

Ease of operationVSLength of stationary object

Solution Approach 1:

The patent inverts the conventional design by allowing the piston ring to extend below the crankcase at bottom dead center. This inversion eliminates the need for a long upper section of the body cylinder, as the piston stroke is accommodated by the downward extension rather than upward extension, thereby reducing the distance between head cylinder and crankcase.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8695561B2Engine and straddle-type vehicle including the engine

Publication Date: 2014.04.15 YAMAHA MOTOR CO LTD

AI summary

An engine that is lighter in weight includes a crankcase, a crankshaft, a body cylinder, a head cylinder, a piston, a piston ring and a cylinder fixing bolt. The piston ring is arranged on an outer peripheral surface of the piston. One end portion of the cylinder fixing bolt extends toward the head cylinder and an other end portion of the cylinder fixing bolt extends toward the crankcase. The cylinder fixing bolt connects the head cylinder, the body cylinder and the crankcase to one another. A lower section of the body cylinder is located within the crankcase. The piston ring abuts on the lower section when the piston is located at a bottom dead center.