Fuel Injection Control Apparatus for Transient Air-Fuel Ratio

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Solution Overview

Problem

The in-cylinder injection valve in internal combustion engines faces challenges in accurately controlling the minimum fuel injection amount due to high fuel pressure, leading to difficulties in achieving a desired air-fuel ratio, especially during transient engine operating states.

Innovation Solution

A fuel injection control apparatus that includes an operating state detection system to adjust fuel injection based on intake air changes, allowing additional injections by the in-cylinder valve and subtracting the minimum injectable fuel amount to ensure accurate fuel delivery, thereby maintaining a desired air-fuel ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high fuel pressure is supplied to the in-cylinder injection valve to enable direct injection into the combustion chamber, then the ability to inject fuel directly into the combustion chamber is improved, but the minimum injection amount increases and injection accuracy deteriorates

Engineering Contradiction:

Improvefuel injection capabilityVSAvoidminimum injection amount accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The fuel injection process is divided into two separate stages: first, the intake passage injection valve injects a base amount of fuel during the intake stroke; second, the in-cylinder injection valve injects an additional small amount of fuel during the compression stroke. This segmentation allows the high-pressure in-cylinder valve to deliver precise small amounts of fuel that would otherwise be impossible to achieve with a single injection event.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The intake passage injection valve performs a preliminary fuel injection during the intake stroke, delivering a base fuel amount before the compression stroke begins. This preliminary action ensures that sufficient fuel is introduced into the combustion chamber early, allowing the subsequent in-cylinder injection to focus solely on delivering the precise additional small amount needed, thereby overcoming the minimum injection amount limitation.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If the minimum pulse width is kept constant, then the valve control simplicity is maintained, but the minimum injection amount increases as fuel pressure rises

Engineering Contradiction:

Improvevalve control simplicityVSAvoidminimum injection amount

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The system performs a partial injection during the intake stroke using the intake passage injection valve, delivering a base fuel amount that is less than the total required fuel. The remaining fuel is injected during the compression stroke by the in-cylinder injection valve. This partial action approach allows the high-pressure system to deliver precise small amounts of fuel that would be impossible to achieve with a single full-stroke injection, effectively overcoming the minimum injection amount limitation while maintaining constant pulse width control.

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If additional fuel injection is performed in the compression stroke to achieve desired air-fuel ratio during transient states, then the air-fuel ratio control is improved, but the injection amount becomes smaller than the minimum injectable amount

Engineering Contradiction:

Improveair-fuel ratio controlVSAvoidadditional fuel injection amount

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the injection timing parameter by performing additional fuel injection during the compression stroke rather than only during the intake stroke. This parameter change allows the in-cylinder injection valve to deliver precise small amounts of fuel (less than minimum injection amount) by utilizing the higher compression pressure and temperature conditions, thereby achieving the desired air-fuel ratio control during transient operating states.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10337447B2Fuel injection control apparatus of internal combustion engine

Publication Date: 2019.07.02 MITSUBISHI MOTORS CORP

AI summary

A fuel injection control apparatus of an internal combustion engine, which can appropriately control the amount of fuel injection from an in-cylinder injection valve so as to achieve a desired air-fuel ratio, regardless of the operating state of the internal combustion engine, is provided. The fuel injection control apparatus comprises: an additional injection means which, when determining that the operating state of the internal combustion engine is a transient state, allows the in-cylinder injection valve to inject a fuel amount conformed to a changing intake air amount; and a subtraction means for subtracting a minimum fuel amount, injectable from the in-cylinder injection valve, from a fuel amount to be injected, before injection by the additional injection means is performed.