Fuel Cutoff Valve Float Segmentation for Molding Precision

Solution Overview

Problem

Conventional fuel cutoff valves experience variability in cutoff fuel level due to temperature changes within the fuel tank, affecting molding precision and productivity during injection molding.

Innovation Solution

A fuel cutoff valve design featuring a float mechanism with a first cup-shaped float body and a second float body that fills the storage chamber, reducing shrinkage and vapor volume, and incorporating a spring support system to stabilize the float mechanism, thereby minimizing buoyancy variations and improving manufacturability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the buoyancy chamber is reduced in size to eliminate vapor expansion effects, then temperature-induced variability in cutoff fuel level is reduced, but molding precision deteriorates due to shrinkage and productivity decreases due to longer cooling time

Engineering Contradiction:

Improvecutoff fuel level stabilityVSAvoidmolding precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The float is divided into two separate parts: a cup-shaped float body and a separate buoyancy chamber. This segmentation allows the buoyancy chamber to be designed as a thin-walled structure that can be quickly cooled and molded with high precision, while the overall float mechanism maintains stability against temperature-induced variability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buoyancy chamber is placed inside the cup-shaped float body, forming a nested structure. This allows the thin-walled buoyancy chamber to be housed within the larger float structure, enabling rapid cooling and precise molding of the chamber while maintaining the overall float's functional integrity and stability.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If the buoyancy chamber is reduced in size to reduce vapor volume, then cutoff fuel level variability is reduced, but productivity decreases due to increased cooling time

Engineering Contradiction:

Improvecutoff fuel level stabilityVSAvoidmolding productivity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The float is divided into two separate parts: a cup-shaped float body and a separate buoyancy chamber. This segmentation allows the buoyancy chamber to be designed as a thin-walled structure that can be quickly cooled and molded with high precision, while the overall float mechanism maintains stability against temperature-induced variability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The buoyancy chamber is placed inside the cup-shaped float body, forming a nested structure. This allows the thin-walled buoyancy chamber to be housed within the larger float structure, enabling rapid cooling and precise molding of the chamber while maintaining the overall float's functional integrity and stability.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Manufacturing precision

If the float wall thickness is reduced to improve molding precision, then shrinkage is reduced, but structural strength may be compromised

Engineering Contradiction:

Improvemolding precisionVSAvoidfloat structural strength

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The float is divided into two separate parts: a cup-shaped float body and a separate buoyancy chamber. This segmentation allows the buoyancy chamber to be designed as a thin-walled structure that can be quickly cooled and molded with high precision, while the overall float mechanism maintains stability against temperature-induced variability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The float combines two different structural elements: a thin-walled buoyancy chamber and a cup-shaped float body. This composite structure allows the thin-walled chamber to provide precise molding while the overall assembly maintains sufficient structural strength through the combined geometry and material properties.

Inventive Principle:

Principle #40Composite materials

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

The design reduces variability in the cutoff fuel level, enhances molding precision, and shortens the fabrication cycle by reducing shrinkage and cooling time, while maintaining superior manufacturability and assembly efficiency.

Implementation Method 1

a spring that presses the float mechanism in a closing direction

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

the float mechanism is raised by a buoyant force, caused by the fuel that has flowed into the valve chamber

Methodology Applied

Scientific EffectBuoyant force: Archimedes' Principle (Buoyancy)

Data Source

PatentUS7571740B2Fuel cutoff valve

Publication Date: 2009.08.11 TOYODA GOSEI CO LTD

AI summary

A fuel cutoff valve is provided with a casing that forms a valve chamber that is connected to a connection conduit, a float mechanism that is housed so as to be able to rise and fall in the valve chamber, and a spring that supports the float mechanism. The float mechanism is structured through an assembly of a first float body and a second float body, where the first float body is provided with a valve portion that opens and closes the connection conduit and provided with a storage chamber that is open on the bottom, where the second float body is housed in the storage chamber to be assembled into the first float body.