Fuel Injector Armature Bolt Radial Mobility Design

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Solution Overview

Problem

Existing fuel injectors face challenges in achieving cost-effective production while maintaining good sealing properties under high operating pressures, as precise radial guidance and self-centering mechanisms require high accuracy and lead to increased production costs and potential leakage due to restricted mobility of the armature bolt.

Innovation Solution

The armature bolt is designed with a section of reduced diameter and increased radial distance from the compression spring, allowing for enhanced radial mobility and self-centering without contact, ensuring effective sealing and reduced production costs through a one-piece component design and conical centering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the armature bolt diameter is reduced to match the valve seat diameter, then the sealing capability is improved, but the radial guidance precision and production cost are worsened

Engineering Contradiction:
Improvesealing capabilityVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The armature bolt features a reduced diameter section specifically at the sealing area to match the valve seat diameter, while maintaining a larger diameter in other areas for structural strength. This local modification provides the necessary sealing capability without requiring the entire bolt to be precisely manufactured to tight tolerances, thereby reducing production costs.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If precise radial guides are implemented for the magnet armature, then the sealing seat accuracy is improved, but the production cost and manufacturing complexity are worsened

Engineering Contradiction:
Improvesealing seat accuracyVSAvoidproduction cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The armature bolt is designed with a conical sealing surface that automatically self-centers when pressed against the valve seat by the compression spring. This self-centering mechanism eliminates the need for complex external radial guides, achieving accurate sealing while significantly reducing manufacturing complexity and production costs.

Inventive Principle:
Principle #25Self-service

3Force

If the armature bolt is surrounded by a compression spring, then the closing force is improved, but the radial mobility of the armature bolt is worsened

Engineering Contradiction:
Improveclosing forceVSAvoidradial mobility
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The armature bolt is segmented into different diameter sections: a larger diameter section for structural support and a reduced diameter section at the sealing area. This segmentation allows the reduced diameter portion to move radially with minimal friction against the compression spring, maintaining both closing force and radial mobility.

Inventive Principle:
Principle #1Segmentation

4Stability of the object's composition

If the armature bolt diameter is increased, then the structural stability is improved, but the sealing capability on the valve seat is worsened

Engineering Contradiction:
Improvestructural stabilityVSAvoidsealing capability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The armature bolt features a reduced diameter section specifically at the sealing area to match the valve seat diameter, while maintaining a larger diameter in other areas for structural strength. This local modification provides the necessary sealing capability without requiring the entire bolt to be precisely manufactured to tight tolerances, thereby reducing production costs.

Inventive Principle:
Principle #3Local quality

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 enhances the radial mobility and stability of the armature bolt, reducing production costs and maintaining effective sealing properties, even under high pressures, by allowing for easier self-centering and minimizing the risk of leakage.

Implementation Method 1

the magnet armature requires relatively precise guidance in the radial direction so that it can ensure the sealing seat... the armature pin is surrounded by a compression spring which urges the armature toward the seat

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

an electromagnetic actuator (32) having an armature plate (31) which is connected to the valve piece (16) in an axially displaceable manner

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP2473728B1Injector for injecting fuel
Publication Date: 2014.11.26 ROBERT BOSCH GMBH
  • EP2473728B1 patent drawingFigure 1
  • EP2473728B1 patent drawingFigure 2

AI summary

The invention relates to an injector (1) for injecting fuel into a combustion chamber of an internal combustion engine, wherein an injection member (10), which releases or closes at least one injection opening (20), is actuated by a control valve (29), wherein the control valve (29) releases or closes a connection (43) from a control space (24) to a fuel return (8) in that a closing member (30) arranged in operational connection to a pressure spring (36) is placed in a seat (34) or releases said seat, and wherein a pin-like element (35), which in the region protruding from the closing member (30) is radially surrounded by the pressure spring (36) and on the side opposite the seat (34) is supported against a stationary support element (37) together with the pressure spring (36), is arranged axially movably in the closing member (30). According to the invention, the closing member (30) is arranged with radial play in relation to a valve piece (16), and the pin-like element (35) has an enlarged radial distance (R) to the pressure spring (36) at least in the contact region with the support element (37).