Variable Valve Actuation for Diesel Exhaust Temperature Control

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Solution Overview

Problem

Diesel engines face challenges in controlling exhaust gas temperature and space velocity during aftertreatment device regeneration, which can lead to thermal damage to engine components and aftertreatment devices due to high exhaust gas temperatures.

Innovation Solution

A method using variable valve actuation to control exhaust gas temperature and mass flow rate by determining maximum safe temperatures and desirable space velocities, sensed through temperature and mass airflow sensors, and adjusting intake and exhaust valve operations to maintain optimal conditions for regeneration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high exhaust gas temperature is used for regeneration, then regeneration efficiency is improved, but thermal damage to engine components and aftertreatment devices occurs

Engineering Contradiction:

Improveregeneration efficiencyVSAvoidthermal damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The exhaust valve timing is dynamically adjusted based on real-time exhaust gas temperature measurements. When temperature exceeds a predetermined threshold during regeneration, the control system modifies the exhaust valve opening/closing timing to reduce exhaust gas temperature, thereby preventing thermal damage while maintaining regeneration efficiency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs a feedback control mechanism where exhaust gas temperature is continuously sensed and compared against predetermined thresholds. Based on this feedback, the control system automatically adjusts exhaust valve timing to maintain temperature within safe operating ranges, resolving the contradiction between achieving high temperature for regeneration and preventing thermal damage

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If variable valve timing is used to control exhaust temperature, then thermal damage is prevented, but device complexity increases

Engineering Contradiction:

Improvethermal damageVSAvoidvalve actuation system complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The variable valve timing system, while adding complexity, provides multiple functions: it controls exhaust gas temperature during normal operation and specifically manages temperature during regeneration events. This multi-functionality justifies the added complexity by solving multiple problems with a single system

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system changes the timing parameters of valve actuation based on operating conditions. By adjusting valve timing parameters dynamically, the system achieves temperature control without requiring additional hardware beyond the existing variable valve timing mechanism, thereby limiting the increase in device complexity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7299623B2Method for controlling exhaust gas temperature and space velocity during regeneration to protect temperature sensitive diesel engine components and aftertreatment devices

Publication Date: 2007.11.27 SOUTHWEST RES INST

AI summary

A method for controlling the temperature and/or space velocity of exhaust gas provides control of the maximum temperature of the exhaust gas to prevent thermal damage to the Diesel engine components and associated aftertreatment devices during regeneration of the aftertreatment devices. The method includes controlling intake and/or exhaust valve opening timing and duration, either singly or in combination with selective individual cylinder cutout, in response to sensed engine operating parameters.