Fuel Injector Injection Law Determination via Rail Pressure Drop

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Solution Overview

Problem

Current methods for determining the injection law of fuel injectors are inefficient and costly, leading to inaccuracies in fuel quantity delivery, especially in the ballistic-operation area, due to constructive tolerance and aging phenomena, which affects combustion efficiency and increases pollution.

Innovation Solution

A method that involves interrupting fuel supply to a common rail, measuring pressure drops during controlled openings of a specific injector, and estimating the injected fuel quantity using pressure sensors, allowing for accurate determination of the actual injection law without additional hardware or complex calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional methods are used to determine injection law with nominal specifications, then production costs are reduced, but injection accuracy deteriorates due to constructive tolerance and aging phenomena

Engineering Contradiction:

Improveinjection accuracyVSAvoidproduction cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention changes the parameter used for injection law determination from nominal specifications to actual specifications measured during engine operation. By measuring the real fuel quantity injected and comparing it with the commanded fuel quantity, the system adapts the injection law to account for constructive tolerances and aging phenomena, thereby improving injection accuracy without increasing manufacturing precision requirements

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system implements feedback by continuously monitoring the actual fuel injection quantity and comparing it with the desired quantity. Based on this comparison, the electronic control unit adapts the injection law parameters to minimize deviations, creating a closed-loop control system that compensates for manufacturing variations and aging effects

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If electromagnetic actuators are designed for high accuracy in ballistic-operation area, then injection accuracy improves, but device complexity and production costs increase

Engineering Contradiction:

Improveinjection accuracy in ballistic areaVSAvoidelectromagnetic actuator complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system enables self-service by allowing the electromagnetic actuators to operate with standard manufacturing tolerances while the control system automatically compensates for inaccuracies through adaptive injection law determination. The system uses real-time measurements and calculations to correct for individual actuator characteristics, eliminating the need for high-precision manufacturing

Inventive Principle:

Principle #25Self-service

3Measurement precision

If adaptive injection law determination is implemented during engine operation, then measurement accuracy improves, but loss of time occurs due to sequential testing of multiple injectors

Engineering Contradiction:

Improveinjection law measurement accuracyVSAvoidtesting time for multiple injectors

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system implements periodic action by determining the injection law for each injector sequentially during scheduled maintenance or initialization phases. The electronic control unit systematically cycles through each injector, performing measurements and calculations in a structured periodic manner, which minimizes the impact on overall engine operation time while ensuring comprehensive calibration

Inventive Principle:

Principle #19Periodic 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 method provides high accuracy in determining the actual injection law, enabling precise combustion control across all engine points, including the ballistic-operation area, without increasing production costs or requiring new hardware, thus improving fuel injection accuracy and reducing pollution.

Implementation Method 1

measuring a pressure drop in the common rail during the opening of the fuel injector to be tested, which is equal to a difference between the initial pressure and final pressure

Methodology Applied

Scientific EffectPressure drop measurement: Pressure Drop

Data Source

PatentUS9212640B2Method for determining the injection law of a fuel injector using a roller-test bench

Publication Date: 2015.12.15 MARELLI EURO SPA

AI summary

A method determines an injection law of a fuel injector to be tested in an injection system and includes steps of: completely interrupting feeding of fuel from a fuel pump to a common rail; avoiding opening of all injectors except for one to be tested; measuring initial pressure of the fuel inside the rail before starting the opening of the injector; opening the injector for consecutive openings with a same test-actuation time; measuring final pressure after ending the opening; determining a pressure drop in the rail during the opening (equal to a difference between the initial and final pressures); estimating, according to the pressure drop, a fuel quantity that is actually injected by the injector when the injector is opened for the time; and causing an internal-combustion engine using the system to rotate by an external actuator during the openings to allow execution of consecutive openings with the same time.