Sensor Thermal Control for Exhaust Aftertreatment Systems

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Exhaust system sensors in internal combustion engines are prone to thermal shock due to rapid temperature changes, leading to potential dew formation and component failure, which can result in incorrect readings and the need for repair or replacement.

Innovation Solution

A controlled heating process is implemented for the sensors, using a thermal model that calculates the sensor temperature based on exhaust mass flow, outlet temperature, and ambient air velocity, activating a heater to maintain a threshold temperature above dew formation risk, typically between 130°C and 160°C, to prevent thermal shock.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sensor is exposed to rapid temperature changes in the exhaust system, then the sensor can detect exhaust conditions, but thermal shock occurs leading to dew formation and sensor failure

Engineering Contradiction:

Improvesensor operationVSAvoidthermal shock

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary heating of the sensor before it is exposed to cold exhaust conditions. The controller activates the heater element to raise the sensor temperature above the dew point before the exhaust flow reaches conditions that would cause condensation, thereby preventing thermal shock and dew formation in advance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system converts the harmful effect of cold exhaust temperatures into a beneficial heating source. When exhaust flow is present, it naturally heats the sensor, and the controller uses this information to reduce or shut off the electric heater, thereby using the exhaust's thermal energy to maintain sensor temperature while reducing electrical power consumption

Inventive Principle:

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

2Reliability

If a heater is used to maintain sensor temperature above dew point, then dew formation is prevented, but energy consumption increases

Engineering Contradiction:

Improvesensor operationVSAvoidheater energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The controller continuously monitors exhaust flow conditions and sensor temperature, using this feedback to dynamically adjust the heater operation. When exhaust flow is detected or sensor temperature approaches the dew point, the controller modulates or shuts off the heater, thereby minimizing energy consumption while maintaining reliable sensor operation through closed-loop control

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The heater operates in periodic cycles rather than continuously. The controller activates the heater intermittently to maintain sensor temperature above the dew point, allowing the sensor to benefit from periodic heating while reducing overall energy consumption compared to continuous operation

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

The controlled heating process effectively reduces instances of thermal shock, ensuring accurate temperature estimation and sensor operation by maintaining the sensor above the dew point, thereby preventing dew formation and extending sensor lifespan.

Implementation Method 1

activating a controlled heating process for the sensor responsive to the calculated temperature being below the threshold temperature. The controlled heating process may include activating a heater to heat the sensor

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

the thermal model includes a conductive heat transfer model when the exhaust mass flow is below a predetermined threshold

Methodology Applied

Scientific EffectConductive heat transfer: Conduction (thermal)

Implementation Method 3

the thermal model includes a convective heat transfer model when the exhaust mass flow is above a predetermined threshold

Methodology Applied

Scientific EffectConvective heat transfer: Convection

Implementation Method 4

one or more sensors to monitor conditions within the exhaust system

Methodology Applied

Scientific EffectTemperature detection:

Data Source

PatentUS11480478B2Temperature estimation for sensor

Publication Date: 2022.10.25 CUMMINS EMISSION SOLUTIONS INC

AI summary

A process for controlled heating of a sensor of an aftertreatment system comprising accessing several parameters, including an exhaust mass flow, an outlet temperature, an ambient air temperature, and an ambient air velocity, calculating a temperature of the sensor based on a thermal model and the accessed parameters, comparing the calculated temperature to a threshold temperature, and activating a controlled heating process for the sensor responsive to the calculated temperature being below the threshold temperature. The controlled heating process can include activating a heater to heat the sensor.