Parasitic Torque Control for Diesel Exhaust Temperature Maintenance

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Solution Overview

Problem

Existing methods for maintaining exhaust temperature in diesel engines, particularly for diesel particulate filter regeneration, fail to effectively utilize a parasitic load and determine minimum load based on exhaust temperature, leading to inefficient particulate matter oxidation at low ambient temperatures or idle conditions.

Innovation Solution

A method and system where a controller determines a target increase in exhaust temperature and torque output for an engine with a continuously variable or hybrid transmission, using a parasitic torque increase via an electrohydraulic pump to maintain a minimum load without increasing the engine's stroke rate, ensuring adequate exhaust temperature for particulate filter regeneration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the engine operates at low load to reduce fuel consumption, then fuel efficiency is improved, but exhaust temperature falls below the threshold required for DPF regeneration

Engineering Contradiction:

Improvefuel consumptionVSAvoidexhaust temperature

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

The patent introduces a parasitic load (electrical load such as alternator, air conditioner, or water pump) as an intermediary mechanism to increase exhaust temperature without increasing engine load. The controller selectively applies parasitic load to generate additional exhaust heat when DPF regeneration is needed, while maintaining low overall engine load for fuel efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the operating parameters of the engine by dynamically adjusting the level of parasitic load based on exhaust temperature measurements and DPF regeneration requirements. The controller monitors exhaust temperature and selectively increases parasitic load parameters only when needed, rather than maintaining constant high engine load.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If the engine load is increased to maintain exhaust temperature for DPF regeneration, then exhaust temperature is improved, but fuel consumption increases

Engineering Contradiction:

Improveexhaust temperatureVSAvoidfuel consumption

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The parasitic load acts as an intermediary that provides the necessary exhaust temperature increase without requiring increased engine load. By using auxiliary components like the alternator or air conditioner, the system achieves DPF regeneration while keeping the main engine load low.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the typically harmful parasitic load (which consumes engine power) into a beneficial tool for DPF regeneration. By strategically applying parasitic load, the system transforms what is normally a source of inefficiency into a means of achieving emissions compliance without sacrificing fuel economy.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If the engine stroke rate is increased to maintain minimum load, then exhaust temperature is improved, but engine wear and fuel consumption increase

Engineering Contradiction:

Improveexhaust temperatureVSAvoidengine wear

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The parasitic load serves as an intermediary mechanism that achieves exhaust temperature maintenance without increasing engine stroke rate. The controller applies parasitic load selectively to generate the necessary thermal conditions for DPF regeneration while keeping the engine operating at lower, less wearful speeds.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical approach of increasing engine stroke rate with an electrical/auxiliary approach using parasitic load. Instead of mechanically increasing engine load and speed, the system uses electrical loads or auxiliary mechanical components that do not directly increase engine wear.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach ensures efficient particulate filter regeneration by maintaining a minimum exhaust temperature, improving filter longevity and reducing the need for excessive engine load, thereby enhancing regeneration efficiency and maintaining a calibrated load without increasing engine stroke rate.

Implementation Method 1

causing, by the controller, a parasitic torque of the engine to be increased based on the target increase to the torque output

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11225920B2Exhaust temperature maintenance using a parasitic load

Publication Date: 2022.01.18 CATERPILLAR INC

AI summary

A power system is disclosed. The power system may include one or more memories and a controller. The controller may determine an exhaust temperature of an engine associated with a continuously variable transmission or a hybrid transmission. The controller may determine a target increase to the exhaust temperature based on the exhaust temperature failing to satisfy a threshold. The controller may determine, based on a lookup table, a target increase to a torque output of the engine based on the target increase to the exhaust temperature. The controller may cause a parasitic torque of the engine to be increased based on the target increase to the torque output.