Venturi Mass Airflow Sensor for Aircraft Engine Fuel Metering

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Solution Overview

Problem

Conventional piston aircraft engines with constant flow mechanical systems, such as those using carburetors, are inadequate for fuel-injected engines as they lack precise control over air mass flow, making it difficult to accurately meter fuel, and existing automotive sensors are too fragile for the harsh aircraft environment.

Innovation Solution

A Venturi-based mass airflow sensing apparatus provides a pressure signal to an electronic engine controller, which generates fuel injector signals for precise fuel delivery to each cylinder, using a durable Venturi meter device and differential pressure sensor to measure air pressure changes, enabling reliable and precise fuel metering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional automotive thin wire pressure sensor is used to measure mass airflow, then measurement capability is provided, but the sensor is too fragile for the harsh aircraft environment

Engineering Contradiction:

Improvemass airflow measurementVSAvoidsensor durability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the fragile automotive thin wire pressure sensor with a Venturi-based mass airflow sensing apparatus that uses differential pressure measurement across a Venturi tube. This mechanical substitution eliminates the fragile wire sensor while maintaining measurement capability through a more robust differential pressure approach that is suitable for harsh aircraft environments.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If a carburetor-based constant flow mechanical system is used, then fuel and air delivery is simplified, but precise control over air mass flow and fuel metering is lost

Engineering Contradiction:

Improvefuel and air deliveryVSAvoidair mass flow control

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements an electronic control system that receives differential pressure signals from the Venturi-based mass airflow sensing apparatus and uses this feedback to precisely control fuel injection timing and quantity. This feedback mechanism enables accurate air mass flow measurement and corresponding fuel metering, replacing the open-loop carburetor system with a closed-loop electronic fuel injection system.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical carburetor system with an electronic fuel injection system controlled by an electronic control unit. This substitution enables precise digital control of fuel delivery based on measured air mass flow, replacing the imprecise mechanical mixing and delivery mechanism of the carburetor with electronically controlled injectors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If manual throttle linkage control is used, then pilot control capability is maintained, but automated precise fuel metering cannot be achieved

Engineering Contradiction:

Improvepilot controlVSAvoidfuel metering control

Core Design Contradiction:

Ease of operationVSExtent of automation

Solution Approach 1:

The patent maintains pilot control through the throttle linkage while enabling automated fuel metering through the electronic control system. The system dynamically adapts by using the pilot's throttle position as an input signal while automatically calculating and controlling fuel injection based on measured air mass flow and engine parameters, combining manual control with automated precision.

Inventive Principle:

Principle #15Dynamics

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 allows for reliable and precise fuel metering to each cylinder of the piston aircraft engine, improving engine operation by accurately determining air mass flow and adjusting fuel delivery, enhancing durability and performance in the aircraft engine environment.

Implementation Method 1

A Venturi-based mass airflow sensing apparatus provides a pressure signal to an electronic engine controller

Methodology Applied

Scientific EffectVenturi effect: Venturi Effect

Implementation Method 2

using a durable Venturi meter device and differential pressure sensor to measure air pressure changes

Methodology Applied

Scientific EffectDifferential pressure measurement: Pressure Gradient

Data Source

PatentUS7827965B2Techniques for delivering fuel to a piston aircraft engine

Publication Date: 2010.11.09 LYCOMING ENGINES A DIV OF AVCO

AI summary

A piston aircraft engine assembly includes a piston aircraft engine, a fuel source, and a control system adapted to deliver fuel from the fuel source to the piston aircraft engine. The control system includes a mass airflow sensing apparatus adapted provide a pressure signal, an electronic engine controller coupled to the mass airflow sensing apparatus, and a set of fuel injectors. The electronic engine controller is adapted to (i) receive the pressure signal from the mass airflow sensing apparatus and (ii) generate a set of fuel injector signals based on the pressure signal received from the mass airflow sensing apparatus. The set of fuel injectors is adapted to meter the fuel in response to the set of fuel injector signals generated by the electronic engine controller.