Fuel Injector Contact Detection Using Constant Current Source

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current fuel injector systems face challenges in accurately determining the contact and non-contact states between moving parts due to small contact surfaces and high, varying impedances, which complicates precise control and measurement of fuel dispensing.

Innovation Solution

A system utilizing a constant current source and transistor switch to detect electrical continuity between moving parts, allowing for precise measurement of current and voltage changes to determine the degree of electrical continuity, thereby improving the accuracy of contact detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If electrical contact switch is used to determine contact between needle and valve seat, then contact detection capability is improved, but measurement precision deteriorates due to high and varying capacitance and complex time dependent impedance behavior

Engineering Contradiction:

Improvecontact detection capabilityVSAvoidmeasurement precision

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by transforming the measurement approach from direct impedance measurement to current measurement. By using a constant current source, the system converts the varying impedance problem into a linear current signal that can be easily filtered and measured, resolving the measurement precision issue while maintaining contact detection capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary constant current source between the power supply and the electrical contact switch. This current source acts as a mediator that converts the complex impedance variations into a stable, linear current signal, enabling precise measurement without being affected by the high and varying capacitance of the contact surfaces

Inventive Principle:

Principle #24Intermediary (Mediator)

2Difficulty of detecting and measuring

If additional wiring and electrical contact switch are provided in injector, then contact detection between moving parts is improved, but device complexity increases

Engineering Contradiction:

Improvecontact detection between moving partsVSAvoiddevice complexity

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent applies universality by making the additional wiring serve multiple functions: it provides both the electrical contact detection path and the measurement current path. The constant current source and associated circuitry are integrated into the existing injector control system, allowing the same wiring to be used for both actuator control and contact detection, thereby reducing overall device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If constant current source is used to measure current through injector, then measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improvemeasurement precisionVSAvoiduse of energy

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by using a constant current source that provides just enough current for accurate measurement without excessive energy consumption. The measurement current is kept separate from and independent of the main actuator current, allowing precise measurement of contact state with minimal additional energy usage while maintaining measurement precision

Inventive Principle:

Principle #16Partial or excessive action

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 solution enhances the precision of fuel injector control by providing a more responsive and less filtered signal, allowing for finer tuning and accurate measurement of fuel dispensing, even with high impedance conditions.

Implementation Method 1

A wire connected to an electrical contact point on said fuel injector from a supply voltage (VICL) forming a circuit allowing current to pass through said injector (Iinj) to ground via said components when said components have a degree of electrical continuity

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentEP3526460B1Method and apparatus to detect impedance of contact between injector valve moving parts

Publication Date: 2022.06.29 DELPHI TECH IP LTD

Figure 1
Figure 2~3
Figure 4

AI summary

A system adapted to detect the electrical continuity between components of an actuator operated fuel injector (1), where said components are adapted move relative to one another in operation, said system including a wire (7) connected to an electrical contact point on said fuel injector from a supply voltage (VICL ) forming a circuit allowing current to pass through said injector (Iinj) to ground via said components when said components have a degree of electrical continuity, and including a constant current source (8) and transistor switch (Q1) connected in parallel such that one terminal of the current source is connected to the supply voltage VICL and a first terminal of the transistor switch, and the other terminal of said current source is connected to said electrical contact and a second terminal of the transistor switch, such that current from the constant current source is adapted to forma first pathway through the injector dependent on said electrical continuity and a second pathway though the switch via the from said second terminal to the third terminal of the transistor switch.