This document summarizes temperature sensors used in automotive applications. It describes two main types of temperature sensors: contact sensors which require direct physical contact like thermocouples, RTDs, and thermistors, and non-contact infrared sensors. It provides details on the structure, working principles, and common applications of these sensors for measuring coolant, air, oil, exhaust, and other temperatures. The document was presented by Hardik Rathod at Chemnitz University of Technology on automotive sensors.

1. Hardik Rathod
Chemnitz University of Technology
Course of Studies M_Es
SS2015 Semester
Temperature Sensors
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun

2. 2
Contents
• Introduction
• Types and short discription
• Structure
• Working principle
• Application in Automotive Domain
• References
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun

3. 3
Introduction
• Physical, electronic, chemical, mechanical and biological systems are
affected by temperature
• Temperature is most often measured quantity
• Most commonly used in Food processing, environmental control, medical
devices, chemical handling and in Automotive
• Used to ensure that a process is either staying with certain range
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun

4. 4
Types
• Two types: 1. Contact
2. Non-contact
• Contact Temperature Sensors:
o Thermocouples
o Resistance Temperature Detectors (RTD)
o Thermistors
o Filled system thermometers
o Bimetallic thermometers
• Non-Contact Temperature Sensors:
o Pyrometer or
o Infrared Temperature sensors
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun

5. 5
Contact Temperature Sensors
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Thermocouples
•Pair of junction formed from two different
metals
•One junction represents reference
temperature, other is the temperature to be
measured
•Temperature difference cause a voltage
that is temperature dependent
•Commonly used sensor (inexpensive,
reliable, do not require power)
•Wide temperature range
Fig.1 Thermocouple structure
Fig.2 Typical thermocouple sensors

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Contact Temperature Sensors
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Fig.3 structure of RTDs
Fig.4 R vs T

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Contact Temperature Sensors
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Fig.5 thermistor characteristic
Fig.6 thermistor

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Contact Temperature Sensors
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Filled system thermometer
•Liquid enclosed in a tube
•Volume of liquid changes as function of
temperature
•Liquids used- Mercury, alcohol
Bimetallic thermometer
•Two metals with different thermal expansion
coefficients are fixed together
•Change in temperature causes expansion in
metal
•Steel and copper are used for this
Fig.7 Filled system thermometers
Fig.8 Bimetallic thermometer

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Non-contact Temperature Sensors
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Infrared temperature sensor
•Measures heat radiated by object
•Thermal energy focused on thermopile using
lens
•Output of thermopile is given to the electronic
package for amplification and further process
•Relatively faster
•Used when direct contact is undesirable
Fig.9 IR temperature sensor
Fig.10 IR gun

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Structure
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Structure
•Sensing element surrounded by metal body
•Typically 2 pin device
Manufacturers
•Bosch, Continental, Delphi, Denso, TI, Beru,
C-Temp, etc.
Fig.11 structure
Fig.12 typical automotive temperature sensors

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Working principle
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
• Constant voltage is supplied to sensor
• Resistance changes with respect to
temperature
• Voltage sensing circuit determines resulting
voltage drop across thermistor
• Resulting signal given is to the control unit
• Control unit takes decisions according to
results
Fig. 13 Working

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Application in Automotive domain
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Coolant temperature Sensor
•Used to adjust fuel injection, ignition timing and cooling fan
Air temperature Sensor
•Installed in the intake air manifold
•Measures temperature of engine intake air
•Range -40 ˚C to +120 ˚C
Engine Oil temperature Sensor
•Calculates engine oil temperature (-40 ˚C to +170 ˚C)
Exhaust Gas temperature Sensor
•Employs platinum measuring resistor (-40 ˚C to +1000 ˚C)
•Used to regulate exhaust gas recirculation
•Mounted in exhaust system

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Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
Fuel temperature Sensor
•Located along fuel delivery system
•Provides fuel temperature (-40 ˚C to +160 ˚C)
Vehicle’s in-out temperature Sensor
•Exterior temperature sensor: located around front bumper area
•Cabin temperature sensor: near or within steering column
Gives signal to HVAC (heating, ventilation and air conditioning) system
Tire and Brake disc temperature Sensor
•Located around tire envelope
•IR temperature sensors employed
Application in Automotive domain

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References
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
[1] The Michigan Chemical Process Dynamics and Controls open text book
https://controls.engin.umich.edu (20, April 2015)
[2] DeVale INDUSTRIES Inc. - http://www.devale.com (20, April 2015)
[3] AZO SENSORS - http://www.azosensors.com (25, April 2015)
[4] WATLOW, Sensor selection guide - http://watlow.com (25, April 2015)
[5] Engine coolant temperature sensor, Wikipedia - http://en.wikipedia.org
(25, April 2015)
[6] CVEL AUTOMOTIVE ELECTRONICS, The Clemson university vehicular
electronics laboratory- http://www.cvel.clemson.edu (10, May 2015 )
[7] FreeASEStudyGuides.com - http://www.freeasestudyguides.com (10, May
2015)
[8] Online Electrical Engineering, electrical4u.com - http://www.electrical4u.com
(10, May 2015)

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References (Figure sources)
Seminar Automotive Sensors
Chair for Measurement and Sensor Technology
Univ.-Prof. Dr.-Ing. O. Kanoun
[Fig.1] Thermocouple structure: maxim integrated, http://www.maximintegrated.com
[Fig.2] Typical thermocouple sensors: Engine thermocouples,
http://www.fwmurphy.co.uk
[Fig.3] and [Fig.4] exsense electronics, http://www.exsense.cn
[Fig.5] and [Fig.6] EAGER learning,
http://eagerlearning.org/practice/sensors/temperature-sensor/
[Fig.7] Filled system thermometer – Liquid filled temperature sensors, FTB
instruments
[Fig.8] bimetallic thermometer, Physics world - http://www.hk-phy.org
[Fig.9] and [Fig.10] measurement specialties, http://www.meas-spec.com
[Fig.11] and [Fig.12] – AutoZone, http://www.autozone.com
[Fig.13] Working – AZO sensors, http://www.azosensors.com