Fuel Injector Coil Spring External Calibration

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Solution Overview

Problem

Fuel injectors face dispersion in fuel flow rate characteristics due to non-adjustable compression spring dimensions, leading to a wide tolerance range that limits production quality.

Innovation Solution

A coil assembly with an adjustable spring calibration mechanism, featuring a deformable part that can be compressed externally to adjust the spring compression, allowing for precise control of the fuel flow rate through a radial bore and adjustment tool engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the spring compression is determined by fixed dimensions during assembly, then the manufacturing process is simple, but the fuel flow rate characteristic has wide tolerance range and poor precision

Engineering Contradiction:
Improvefuel flow rate characteristicVSAvoidadjustment mechanism
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The spring compression is made adjustable through a deformation element that can be modified by an external adjustment tool. The deformation element changes its dimensional characteristics (length or position) when acted upon by the adjustment tool, allowing dynamic adjustment of spring compression to achieve precise fuel flow rate characteristics while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention allows changing the physical parameters of the spring compression system by deforming a specific element. The deformation element's dimensions or position can be modified to adjust the spring compression force, thereby changing the fuel flow rate characteristic without requiring complete redesign of the assembly dimensions.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If tighter manufacturing tolerances are applied to individual dimensions, then the fuel flow rate tolerance range is restricted, but the production quality improvement is limited and manufacturing cost increases

Engineering Contradiction:
Improvefuel flow rate tolerance rangeVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Instead of relying on tight manufacturing tolerances for fixed dimensions, the invention introduces a dynamic adjustment capability. The deformation element can be modified after assembly to achieve the desired fuel flow rate precision, eliminating the need for expensive tight tolerances on multiple individual components.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention enables parameter adjustment (spring compression) through a simple deformation mechanism rather than requiring precise control of multiple dimensional parameters during manufacturing. This approach achieves the desired tolerance range while maintaining ease of manufacture and lower production costs.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the spring compression is fixed during assembly, then the device structure is simple, but the fuel injector lacks adaptability for calibration adjustments

Engineering Contradiction:
Improvespring calibration adjustabilityVSAvoidadjustment mechanism
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention introduces a minimal dynamic element (the deformation element) that enables calibration adjustment. This element can be deformed by an adjustment tool to modify spring compression, providing adaptability for calibration while adding only minimal complexity to the overall device structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention enables calibration adaptability by allowing parameter changes in the deformation element's dimensions or position. This single element's modification is sufficient to adjust the spring compression and achieve the desired fuel flow rate characteristics, providing versatility without significant structural complexity.

Inventive Principle:
Principle #35Parameter changes

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

Enables fine-tuning of the fuel flow rate within a predefined tolerance range, improving the production quality of fuel injectors by allowing for external adjustment of the spring calibration.

Implementation Method 1

When the solenoid valve is energized it generates a magnetic field which attracts a magnetic core integral with a control valve spool

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a compression spring housed in a bore provided in the heart of the solenoid valve pushes back the magnetic core and the control valve spool closing said evacuation channel

Methodology Applied
Scientific EffectElastic force: Elasticity

Data Source

PatentEP3344867B1Fuel injector having external setting of the coil spring
Publication Date: 2020.08.12 DELPHI TECH IP LTD
  • EP3344867B1 patent drawingFigure 1~2
  • EP3344867B1 patent drawingFigure 3~4
  • EP3344867B1 patent drawingFigure 5~6

AI summary

A coil assembly includes an electric coiling included in an overmold, the coiling being suitable to drive the control valve of a fuel injector. The coil assembly is provided with a longitudinal bore suitable for receiving a spring and with an adjusting member for the setting of the spring which can be moved from outside the injector, the adjusting member forming a transfer of movement such that the movement of the adjusting member from outside the injector is transformed into a compression of the spring.