Fuel Injector Retaining Ring for Noise Damping

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Solution Overview

Problem

Existing fuel injection devices face challenges in noise reduction and tolerance compensation, particularly in direct injection systems, where complex and costly solutions are required to manage structural and airborne noise, and manufacturing tolerances, often resulting in unfriendly installation and high production costs.

Innovation Solution

A compact, solid retaining ring with a cushion-like cross-section is used to decouple the fuel injector from the cylinder head, providing noise damping and tolerance compensation, featuring a captive design with functional areas for holding, securing, centering, and pre-positioning, made from injection-molded plastic or cold-formed aluminum, ensuring easy installation and high fatigue strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a multi-layered intermediate element with damping material is used to reduce noise, then noise damping is improved, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvenoise emissionsVSAvoidintermediate element structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent combines the decoupling function, damping function, and retention function into a single integrated intermediate element. This element comprises a first part with a damping function (absorbing vibrations and noise) and a second part with a retention function (securing the fuel injection valve), eliminating the need for separate damping layers and retaining structures while achieving all required functions in one component.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The intermediate element is designed as a universal component that simultaneously performs multiple functions: it decouples the fuel injection valve from the cylinder head, dampens vibrations and noise through its damping material, compensates for manufacturing tolerances, and secures the valve through its retention structure. This multi-functional design simplifies the overall device architecture.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a retaining O-ring is used to secure the decoupling element, then retention is improved, but the O-ring dissolves during engine operation causing reliability issues

Engineering Contradiction:
Improveretention securityVSAvoidservice life of retaining element
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent replaces the dissolvable rubber O-ring with a retaining structure made from temperature-stable plastic material that does not dissolve during engine operation. This retaining structure is designed to withstand the thermal and mechanical conditions throughout the engine's service life, eliminating the reliability issue associated with dissolvable retaining elements.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If a complex multi-part intermediate element is used for tolerance compensation, then adaptability is improved, but ease of manufacture and installation deteriorate

Engineering Contradiction:
Improvetolerance compensation capabilityVSAvoidproduction complexity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple functional parts into a single intermediate element that can be manufactured as one piece using injection molding or similar processes. The element includes a damping portion for absorbing vibrations, a retention structure for securing the valve, and a geometry designed to compensate for manufacturing tolerances in both the fuel injection valve and cylinder head, achieving adaptability without manufacturing complexity.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If a solid single-piece intermediate element is used, then ease of manufacture is improved, but noise damping capability deteriorates

Engineering Contradiction:
Improveproduction simplicityVSAvoidnoise emissions
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The intermediate element is manufactured as a single piece using composite materials, specifically a plastic base material reinforced with damping material or designed with a cellular/corrugated internal structure. This composite construction provides both the structural integrity needed for a single-piece manufacture and the vibration-damping properties required for noise reduction, combining the benefits of simplicity and noise control.

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 solution effectively reduces noise emissions and maintains secure retention of the fuel injector during operation, allowing for quick assembly and disassembly, while being cost-effective and resistant to temperature variations, thus addressing the limitations of existing technologies.

Implementation Method 1

The damping material, made of metal, rubber, or PTFE, is selected and designed to dampen the vibrations and noise generated by the operation of the fuel injection valve.

Methodology Applied
Scientific EffectVibration damping: Damping

Implementation Method 2

The retaining ring is made of an elastic material and has a captive design, in that it prevents the decoupling element from slipping off before the fuel injection valve is mounted in the receiving bore.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3234346B1Fuel injection device
Publication Date: 2020.03.18 ROBERT BOSCH GMBH
  • EP3234346B1 patent drawingFigure 1
  • EP3234346B1 patent drawingFigure 2~3
  • EP3234346B1 patent drawingFigure 4

AI summary

The fuel injection device according to the invention is characterized particularly by providing a low-noise and pivotal structure. The fuel injection device comprises at least one fuel injection valve (1), a receiving bore (20) in a cylinder head (9) for the fuel injection valve (1), and a decoupling element (25) between a valve housing (22) of the fuel injection valve (1) and a wall of the receiving bore (20). The decoupling element (25) is arranged on the fuel injection valve (1) in a captive manner before the fuel injection valve is assembled in the receiving bore (20), wherein a securing ring (29) is attached to the outer circumference of the fuel injection valve (1) below the decoupling element (25), and the securing ring (29) is a closed plastic ring. The fuel injection valve is particularly suitable for injecting fuel directly into a combustion chamber of a mixture-compressing spark-ignited internal combustion engine.