automotive temperature sensors

Hardik Rathod

Chemnitz University of Technology

Course of Studies M_Es

SS2015 Semester

Temperature Sensors

Seminar Automotive Sensors

Chair for Measurement and Sensor TechnologyUniv.-Prof. Dr.-Ing. O. Kanoun

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Contents

• Introduction

• Types and short discription

• Structure

• Working principle

• Application in Automotive Domain

• References



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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



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



5

Contact Temperature Sensors



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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Fig.3 structure of RTDs

Fig.4 R vs T

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Fig.5 thermistor characteristic

Fig.6 thermistor

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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



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



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



• 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



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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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

14

References



[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)



[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

automotive temperature sensors

Education

temperature temperature

ir temperature sensor

sensor technology

temperature dependent

reference temperature

temperature difference

temperature causes expansion

typical thermocouple