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Blog: Measuring automotive exhaust gas temperature

An important part of reducing the emissions of diesel combustion engines depends on knowing the temperature of the exhaust gases - let’s take a closer look at this topic:

Starting in the early 1990s, legislators around the world began to limit the amount of pollutants emitted by motor vehicles to protect the environment. While CO2 and other emissions from petrol-engines is a concern, a more significant focus has clearly been on the diesel engine.

The result - despite all the negative headlines - is, that today's diesel vehicles are significantly cleaner than 10 or 15 years ago. There are a lot of improvements but importantly amongst these are temperature sensors, measuring directly in the exhaust pipe. This is a very demanding environment and, since the introduction of the EURO 5 emission standard in 2008 that demands diesel particulate filters, TT Electronics has been actively involved in meeting this requirement.

Diesel particulate filters need temperature sensing for the regeneration process

To be effective, diesel particulate filters must be regularly regenerated during operation. Regeneration is an internal burning process, which starts at about 500 °C, and takes place without any involvement from the driver. Due to exothermicity, the release of heat during a chemical reaction, temperatures in the range of 700 to 800 °C can be achieved, which allow accumulated soot to be burnt off. In addition to pressure monitoring, which will be discussed in a later blog, temperature detection plays an important role in this process.

TT Electronics’ engineering involvement in such applications began in 2005. At that time, TT Electronics was able to purchase a license for a very robust temperature sensor setup. Subsequently based on the company’s long term experience with temperature sensors and with significant further engineering investment, TT Electronics has refined its exhaust sensor design and made it ready for high volume production.

 

 

 

Robust design is key for the harsh environment in the exhaust pipe of diesel engines
The outcome is a very robust temperature sensor, based on a passive resistance measuring element that responds with different resistance values at different temperatures. Platinum is used as the resistance material as this element is characterised by a nominal resistance of 200 Ohm at 0 °C (PT-200).

The most important advantage of this high-temperature sensor is its robust design. The measuring element is embedded in a monolithically closed tube made of a special stainless steel using a particular ceramic powder mixture. The bubble-free filling of the sensor tip ensures that motor vibrations do not pose a threat to the sensor's service life. In addition, the sensor can be bent from 0 to 120°. Specially developed seals guarantee a long service life even under the harshest environmental conditions in and around the exhaust pipe.

The next level of high temperature design is up to 1200 °C

The experience gained in the last few years has enabled TT Electronics to develop a new generation of high-temperature sensors. The aim of this development was to make a sensor technology suitable for use in vehicles that require temperature measurement up to 1200 °C, which is the case in petrol engines.

Robust sensor design

TT Electronics’ sensors incorporate N-type thermocouples to send continuous measurement signals to the vehicle’s control electronics. Thermocouples use the physical effect of thermoelectricity. A pair of metallic conductors of different materials are joined at one end. Due to the temperature gradient between the measuring point (hot side) and the plug side (cold side) an electric voltage is generated (see Wikipedia). This electrical voltage is proportional to the temperature change on the hot side and can thus be processed as a sensor signal. An electronic unit, which is integrated into the plug housing, provides the necessary signal processing.

Thermocouples have been used for many years in industrial electronics for temperature measurement. TT Electronics’ sensor has been specially adapted to the requirements of automotive applications and only use welded or soldered connections to avoid signal interruption. Protective housings at the sensor tip are made exclusively from high-temperature-resistant stainless steel, using deep-draw technology. The sensors can be attached to the exhaust pipe with a union nut or hollow screw of various dimensions. Cable shields are used to allow high temperature resistance measurements in the vicinity of exhaust pipes.

Various electronic interfaces are available

The electrical signal, as already mentioned, is processed electronically. Users can choose between different digital interfaces. To date, TT Electronics has implemented PWM, SENT and CAN (according to SAE J1939). Like the entire sensor, the electronics unit offers protection class IP6K9K (with its mating connector).

This sensor is suitable for temperature measurements in the range -40 to 1200 °C. With these characteristics, the sensor can be used at any point in the exhaust pipe of petrol engines. Manufacturers of turbo-charged vehicle engines can also use this sensor in the exhaust manifold (before the turbocharger) to warn against excessive temperatures, which can be dangerous for the turbocharger.

Double high temperature sensors will be required for next generation of petrol engines

With the introduction of the latest emission standard (EURO 6c), direct-injection petrol engines must also be equipped with particulate filters for the first time. These use slightly different regeneration processes that, while similar to the particulate filters in diesel engines, need to operate at higher temperatures and require temperature measurements at two points.

Precisely for this application, TT Electronics has developed a thermocouple sensor as a double module that combine two sensors with one electronics unit. Apart from cost benefits, this allows the sensors to be matched with tolerances of +/- 1 °C.

 

 

If you would like to learn more about this sensor concept, watch the product Video

Blog: Sensors are critical to enabling greener vehicle emissions

Blog: Sensors are critical to enabling greener vehicle emissions

Frank Rothe, Product Application Manager Sensors, considers the importance of sensors in the drive to greener vehicle emissions

 

Mobility is essential to modern life, and is a key driver for economic growth. At the same time, the world's ever-increasing traffic volumes are a major source of pollution, which poses a fundamental threat to our future.

 

The solution lies in emission-free transport, an aim that leading car manufacturers and developers around the globe are working towards intensively. Until that goal can be fully achieved, new electronic systems and technologies will be instrumental in reducing emissions from combustion engines.

 

TT Electronics is a recognised expert in this specialist field, where the impact that exhaust fumes, extremely high temperatures and other aggressive factors can have on surrounding components represents a significant challenge.

 

An example of these increasing demands can be found in the latest generation of high-power vehicles, where the combustion process generates ultra-high temperatures to keep emissions down. These temperatures can harm the engines’ expensive turbocharger systems, meaning that precise monitoring is required to ensure temperatures remain within acceptable bounds, and to limit the engine power, should the acceptable range be exceeded. Our state-of-the-art temperature sensors can monitor this. They transfer thermal data as electrical information which can be handled by engine control units (ECU). For the driver of the car, the impact is barely noticeable.

 

TT Electronics’ sensors excel in their ability to withstand a variety of corrosive gases and aggressive liquids, thanks to their extremely robust housing. This level of protection has traditionally come at the expense of inferior temperature measurement: enclosing the cells typically makes them slow to detect changes in temperature, when what we need for turbocharger applications is real-time information. This is where our long experience and sophisticated modular mechanics concepts come in. Combined with endlessly tried-and-tested technologies such as thermal resistive like PT-200 and others, our sensors are highly responsive and extremely resistant to harmful external factors. The variety of available technologies and our ability to design customised solutions have already proved a competitive advantage in many cases.

 

Further limitations on specific pollutants (soot particles, nitrous oxides, CO and CO2) have been introduced at regular intervals for on-road and off-road vehicles. Europe and the USA have played a pioneering role, and their regulations generally provide a model for other countries around the world.

 

The currently applicable emissions standards are EURO 6, EPA 13 (both on-road) and Tier4final (off-road). The limits defined by these standards are forcing vehicle and engine manufacturers to introduce sophisticated exhaust after-treatment systems, as well as modifying their engines. The most important adaptations are diesel oxidation catalysts (re-oxidation of unburned hydrocarbons), diesel particulate filters (retention of rust particles) and selective catalytic reduction (conversion of harmful nitrous oxides in nitrogen and water).

 

While this change has so far mostly affected diesel engines, some petrol engines – particularly those with direct fuel injection – will have most likely to be fitted with gasoline particulate filters from September 2018 at the latest, when the next stage of the emissions standard (EURO 6c) is due to come into force.

 

To implement these measures effectively, we will need extreme systems that are able to support control algorithms, so that initial process and end values can be measured and transmitted in a suitable form to the vehicles’ electronic control units (ECUs). Sensors for key indicators measure the relevant physical properties, converting them into electrical signals and then relaying them to the ECU.

 

For these specific requirements, TT Electronics has a broad portfolio of temperature, pressure and fluid quality sensors, which we will expand upon in the future.

 

Best regards

 

 Frank Rothe

 

Frank Rothe

Product Application Manager Sensors

Whitepaper

Our white paper will provide technical and background knowledge on the important issues of Sensing and Control industry. After a short registration on our website, we will send you our free White Paper via email. Currently we are happy to inform you on the following topics:

SIMPSpad - Magneto-inductive position sensing

ECUs - Electronic Control Units for e-traction drive

MCUs - Motor Control Units

In the media

High-temperature sensor - Technical article in Diesel Progress 2017

TT Electronics makes high-temperature sensor technology used in passenger cars available for heavy duty trucks, off highway equipment.

 

 » Download PDF Article

» Learn more about High-temperature sensors

Haptic pedals - Technical article in ATZ elektronik 01 2017

Haptic pedals - The new information source for the driver

 

» Download PDF Article

» Learn more about haptic pedals

New emission norms - Technical articles in Motorindia Dez/2016

TT Electronics confident of robust growth in Indian market
New emission norms to propel company prospects

 

» Download PDF Article

» Learn more about Exhaust-after-treatment

Presentation of Ralph Stömmer at IDTechEx – Vehicle Electronics Magazine 06/2016

Vehicle Electronics magazine reported on Ralph Stömmer's presentation on the IDTechEx Congress in March, where he spoke on "Electric Vehicles: Everything is Changing"– read the article in the new issue on page 15 and learn more about new visions and concepts about Future 48V Motor Controllers.


» Download PDF Article
» Download presentation (short form)
» Learn more about our 48V technologies

LED-Precision-Mounting – Technical article in ATZ Elektronik 06/2015

LED-Precision-Mounting replaces LED-Arrays with single LED-Chips.The process enables the individual placement of Single-Chip-LEDs with a positioning accuracy of ± 50µm of the light emitting area while enabling individual lighting illustration.

 

» Find more details about our LED technology in latest essay of ATZ Elektronik

» Learn more about LED-Precision-Mounting

» Erfahren Sie mehr über unser Product portfolio for Controls

Fluid properties sensor technical article - Diesel Progress China 02/2015

Fluid properties sensors optical-based detect continuously and very accurately the concentration of urea in DEF / AdBlue ® / UREA (aqueous urea solution) and thus contribute substantially to comply with the latest emission standards for.


Learn more with the latest essay of issue of Diesel Progress China (Chinese language):
» Extract of Diesel Progress China edition 02-2015

 

» Learn more about Fluid Properties Sensors

» Learn more about our wide product portfolio for exhaust after treatment

HSRP technical article - Emobilitytec - 04/2015 (German language)

HSRP - High accuracy resolver for e- drives


Learn more with the latest essay in Emobilitytec (German language):

Extract of Emobilitytec edition 04/2015 (German language)

 

» Learn more about HSRP Sensor

» Learn more about our product portfolio for Speed Sensors

HSRP technical article - Automobil Elektronik - 09-10/2015

HSRP – Rotation speed sensors for driver assistance.


Learn more with the latest essay in Automobil Elektronik (German language):

Extract of Automobil Elektronik edition 09-10/2015

 

» Learn more about HSRP Sensor

» Learn more about our product portfolio for Speed Sensors

 

 

Power Stack technical article - Hanser Automotive - Emobility 10-2015

Power Stack – Power electronics for 48 V on board system.


Learn more with the latest essay in Hanser Automotive - Emobility (German language):

Extract of Hanser Automotive - Emobility edition 10-2015

 

» Learn more about Power Stack

» Learn more about our product portfolio for Controls

Fluid properties sensor technical article - Diesel Progress international 10-2015

Fluid properties sensors – Continuous sensing of Urea Quality and Urea concentration in DEF / AdBlue® / UREA aqueous solution: AB Elektronik begins series production of Fluid Quality Sensor first introduced in 2014.


Learn more with the latest essay in Diesel Progress international:

Extract of Diesel Progress international edition 10-2015

 

» Learn more about Fluid Properties Sensors

» Learn more about our product portfolio for Exhaust After Treatment

HSRP Position Sensor - Technical article on allelectronics.de 10/2015 (German language)

Higher resolution and faster measurement - HSRP - rotation speed sensors for ADAS
While the current differential Hall sensors now come to the limits of their maximum accuracy, the HSRP technology is in its infancy. It offers great potential for the next generation of rotary position sensors. 

 

» Read the article on allelectronics.de

 

» Learn more about HSRP Sensor

» Learn more about our product portfolio for Speed Sensors

 

 

 

Fluid properties sensor technical article - AI Magazine China 07/2015

Fluid properties sensors optical-based detect continuously and very accurately the concentration of urea in DEF / AdBlue ® / UREA (aqueous urea solution) and thus contribute substantially to comply with the latest emission standards for.


Learn more with the latest essay of issue of AI magazine (Chinese language):
» Extract of AI Magazine edition 07-2015

 

» Learn more about Fluid Properties Sensors

» Learn more about our wide product portfolio for exhaust after treatment

Electronic pump control – Technical Article ATZ Elektronik 04/2015

The customer-specific control module is fully integrated into the electric motor and includes all components which are necessary for the control of an electronic motor by using best cost/benefit ratio in technology and materials. The inputs from the master control unit are transmitted via PWM, LIN or CAN to the microcontroller which calculates the speed and the necessary commutation of the electronic motor (block, trapezoidal or sine). With gate driver and power MOSFET the coils of the motor are energized. In this process the speed (with or without sensors), current, voltage and temperature are monitored and in case of an error reported back to the master control unit.

 

Learn more about the savings by further development of power electronics on our website: http://www.abelektronik.com/mcu.

 

» Learn more about Electronic pump control 

» Learn more about our product portfolio for Controls

 

 

AB Mikroelektronik receives VERENA award - Automobilkonstruktion 02/2015

Automobilkonstruktion is reporting about AB Mikroelektronik receiving the VERENA award 2015 for innovative Power Stack technology.


AB Mikroelektronik developed the first to the market process for soldering of electronic components to Aluminum which makes Power Electronics for E-Drive much more eco-friendly and offers also a very high cost/efficiency benefit.


» Read the full magazine (German language)
» Learn more about Power Stack technology

TT Electronics to expand product range in India - Autocar Professional 02/2015

Amrei Drechsler (EVP, Sensing and Control – Transportation) and Lokesh Payik (Country Leader & Head, Engineering Centre India) have given an outlook on TT Electronics India location in the interview with Autocar Professional: Starting out its India innings as a two-wheeler centre of excellence, TT Electronics is now eyeing clients in passenger vehicles, commercial vehicles and tractors.


Read the complete article of the latest essay of Autocar Professional (India)

 

 

Fluid properties sensor technical article - Electronic Products 02-2015

Continuous sensing of Urea Quality and Urea concentration in DEF / AdBlue® / UREA aqueous solution.

Using special optical techniques, AB Elektronik’s sensor is capable of detecting variances in urea concentration as small as +/- 2 %, and can operate at temperatures from -10 degC to +85 degC.
The optical measurement principle is robust against dirt and moving fluids including gasoline, diesel or coolant.

 


Learn more with the latest essay in Electronic Products:

Extract of Electronic Products edition 02-2015

 

 

Mechatronics for safety, convenience and efficiency in October’s Vehicle Electric Electronics

Electronic control of mechanical automotive applications presents highly demanding design challenges, requiring experience in conventional PCB and specialised high temperature thick film substrate technology, to create reliable mechatronic system solutions.


Published Article PDF

More information

Mechatronics for safety, convenience and efficiency in October’s Vehicle Electric Electronics

Electronic control of mechanical automotive applications presents highly demanding design challenges, requiring experience in conventional PCB and specialised high temperature thick film substrate technology, to create reliable mechatronic system solutions.

You can read the paper in 2 formats:

Published Article PDF

White Paper PDF

- See more at: www.ttelectronics.com/en/news-and-media/in-the-media/octobers-vee-article

Mechatronics for safety, convenience and efficiency in October’s Vehicle Electric Electronics

Electronic control of mechanical automotive applications presents highly demanding design challenges, requiring experience in conventional PCB and specialised high temperature thick film substrate technology, to create reliable mechatronic system solutions.

You can read the paper in 2 formats:

Published Article PDF

White Paper PDF

- See more at: www.ttelectronics.com/en/news-and-media/in-the-media/octobers-vee-article

Fluid properties sensor technical article - Diesel Progress international 10-2014

Fluid properties sensors – Continuous sensing of Urea Quality and Urea concentration in DEF / AdBlue® / UREA aqueous solution.


Learn more with the latest essay in Diesel Progress international:

Extract of Diesel Progress international edition 10-2014

 

 

KTM E-Bike technical article - emobility tec 09/2014

TT Electronics develops ECU for KTM Freeride E bike


Learn more with the latest essay in emobility tec (German language)

 

 

 

Magnetorque® Plus technical article - Automobilkonstruktion 09-2014

Magnetorque®  Plus – A compact solution for torque and position sensing

 


Learn more with the latest essay in Automobilkonstruktion (German language).

 

 

 

Magnetorque® Plus technical article - Power World 09-2014

Magnetorque®  Plus – A compact solution for torque and position sensing

 


Learn more with the latest essay in Power World (German language):

Extract of Power World edition 09-2014

 

 

Fluid properties sensor technical article - Power World 09-2014

Fluid properties sensors – Continuous sensing of Urea Quality and Urea concentration in DEF / AdBlue® / UREA aqueous solution.


Learn more with the latest essay in Power World (German language):

Extract of Power World edition 09-2014

 

 

Magnetorque® Plus online article - Automobilkonstruktion 06-2014

Magnetorque®  Plus – A compact solution for torque and position sensing

 
Learn more with the latest essay online on autokon.de (German language)

SIMPSpad technical article - Automobilelektronik 01/2014

Position Sensing – Customized Technologies

Learn more with the latest essay in Automobilelektronik (German language):

Extract AEL edition of 1-2014

Full version AEL edition of 1-2014

Press Releases

AdBlue® / DEF quality sensor

Optical sensor uses the refractive index to log AdBlue® quality
Since the introduction of the EURO 5 standard and especially in accordance with US 10 and EURO 6, the NOx proportion of exhaust gas in high performance diesel engines has to be reduced with the assistance of SCR technology (selective catalytic reduction). This is achieved by dosed supply of a water based urea solution, so-called AdBlue®, to the exhaust flow. According to the latest requirements, the quality of the urea solution requires permanent monitoring.

 

Read more

Graphic download

Magnetorque® Plus - Sensor for Transportation Electronic Power Steering

Magnetorque® Plus provides compact solution for torque and position sensing

TT Electronics’ Sensing and Control division has expanded its series of sensors for electronic power steering (EPS) applications.  The new Magnetorque® Plus combines TT Electronics’ proven non-contacting torque sensor with a multi-turn position sensor in a single compact package. The integrated and fully calibrated design is significant in providing engineers with an integrated solution for measuring torque and steering wheel angle.

 

Read full article here

Graphic download

LED modules for automotive headlights applications
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Blog: Measuring automotive exhaust gas temperature

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Please find Annual Results for year ended 31 December 2016 on the TT Electronics website
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