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UNIT 5
5
Sensors &Αctuators
VOCABULARY
SKILLS WORK
FUNCTIONS
QUIZ
Lead-in activity
Reading A
Learn about sensors and
Click on the icon and fill the
Sensors and actuators
actuators
gaps
carefully and fill the Reading B
Learn & Identify common
Click the icon and solve the
gaps
Common types of Sensors
sensors and actuators types in
crossword
& actuators
an vehicle
Watch the images
Watch carefully the
image. Click the
Spell each Sensor & Actuator
icon to watch the
name
video
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Click the icon and solve the
multiple choises exercise
In this Unit, you will learn:

Sensors and actuators are the sensing and also
the acting of the engine
 The basic types of sensors and actuators which are used in a vehicle
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UNIT 5
Sensors & Actuators
 ICE Sensors
 ICE Actuators
 ICE data management
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Lead-in Activity: Lead-in Activity: Watch the images carefully and fill the gaps below.
a. An _________ _________ transforms electricity into mechanical energy or motion.
b. A _____________ converts sound in to electric pulses.
c. The ________________ sensor is a NTC resistor.
d. In order to check the exhaust gases we use an ________ or ___ sensor.
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Watch carefully the following image. Then click on the image to watch the video!
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2
Reading: Read the text carefully.
Sensors and actuators
Computer controlled systems monitor the operating condition of today vechicles. Through sensors computer receive vital information about
many conditions of the engine sensors are the computer’s eyes as they convert physical signals (e.g tempreture,pressure) into digital or analog
electrical signals.
There are three main categories of sensors used in automobiles:
Resistive sensors, Voltage generating sensors, Switch sensors.
On the other hand actuators are the devices uses energy to provide motion.(e.g electric motors, step motors, valves).
We could say that actuators complete the control process by carrying out the computer’s instuctions . An actuator can adjust engine idle speed
or regulate the fuel metered into the engine.
Actuators are divided into the following areas : Electric motors, Stepper motors, Solenoids.
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At the following image we can see a gasoline engine’s sensors and actuators. Spell their names!
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3
Application I
Fill in the blanks using the words given. Click on the icon to start! Must reach 70% to be satisfied!
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Reading: Read the text carefully.
Common Sensors types
Resistive sensors
Manifold Absolute Pressure (MAP) Sensor
The manifold absolute pressure sensor is a variable resistor used to monitor the difference in pressure
between the intake manifold at outside atmosphere. This information is used by the engine computer to
monitor engine load (vacuum drops when the engine is under load or at wide open throttle). When the engine
is under load, the computer may alter spark timing and the fuel mixture to improve performance and
emissions.
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Engine Coolant Temperature (CTS) Sensor
An ECT sensor is a simple sensor that it’s fitted in the engine’s block or cylinder head and
determines the temperature of the engine coolant. Basically is a thermistor that can change its
resistance with engine coolant temperature changes, usually a NTC type –Negative Temperature
Coefficient. The resistance reading by the ECM can be used to change the air/fuel ratio and the
ignition timing, to activate emission control or turn the cooling fan on.
Voltage generative sensors
Knock sensor
Engine knock is characteristic of an uncontrolled combustion process and can cause engine damage. That is
prevented by a knock sensor, a noise sensor near the engine. The Knock Sensor is a Piezo Electric device that
when you stress it, a voltage is produced. It senses knock and transmits information to the electronic engine
management control unit. This influences process control in the engine, for example timing and fuel injection
until knock is eliminated. Knock is frequently caused by fuel that does not comply with the required minimum
quality.
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λ or oxygen sensor
An Oxygen sensor is a chemical generator. It is constantly making a comparison
between the Oxygen inside the exhaust manifold and air outside the engine. If this
comparison shows little or no Oxygen in the exhaust manifold, a voltage is generated.
The output of the sensor is usually between 0 and 1.1 volts. All spark combustion
engines need the proper air fuel ratio to operate correctly. For gasoline this is 14.7 parts
of air to one part of fuel. When the engine has more fuel than needed, all available
Oxygen is consumed in the cylinder and gasses leaving through the exhaust contain
almost no Oxygen. This sends out a voltage greater than 0.45 volts. If the engine is
running lean, all fuel is burned, and the extra Oxygen leaves the cylinder and flows into
the exhaust. In this case, the sensor voltage goes lower than 0.45 volts. Usually the
output range seen seen is 0.2 to 0.7 volts.
Switch sensors
Throttle position (TPS) sensor
The TPS is a potentiometer attached to the throttle shaft. A voltage signal is supplied to the sensor,
and a variable voltage is returned. The voltage increases as the throttle is opened. This signal and
the MAP output determines how much air goes into the engine) so the computer can respond
quickly to changes, increasing or decreasing the fuel rate as necessary
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Brake sensors
Brake sensors are used in vehicle applications such as travel sensor for brake master cylinder
position detection (optional redundant); travel sensor for rear axle steering to support advanced
ESP; rotary sensor for brake pedal position detection (optional redundant); hall brake light switch
and wheel speed sensor. We also provide pressure sensors such as the vacuum brake booster
sensor.
Actuators types
Stepper motors
Digital Linear Actuator – Idle Air Control Valve
The Digital Linear Actuator has two major functions:
Idle Air Control Valve in the gasoline engine vehicles equipped with mechanical throttle
body. The valve allows accurate and precise air flow during idle phase. Accurate and precise
linear positioning against external load.
The Idle Air Control Valve offers:





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Accurate and stable idle air control
Various gas (air) flow curve can be achieved
High accuracy under severe conditions
Proven reliability and long durability
High resolution linear positioning against load
Solenoids
Injectors
Fuel Injectors are solenoids valves. Usually, the injector have
two pins. One pin is connected to the battery through the
ignition relay and the other pin goes to the ECU. The ECU
sends a pulsing ground to the injector, which closes the circuit,
providing the injector's solenoid with current. The magnet on
top of the plunger is attracted to the solenoid's magnetic field,
opening the valve. Since there is high pressure in the rail,
opening the valve sends fuel at a high velocity through the
injector's spray tip. The duration that the valve is open- and
consequently the amount of fuel sent into the cylinder- depends
on the pulse width -how long the ECU sends the ground signal
to the injector. When the plunger rises, it opens a valve and the
injector sends fuel through the spray tip and into either the
intake manifold, just upstream of the intake valve, or directly
into the cylinder. The former system is called multiport fuel
injection and the latter is direct injection.
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Application II
Let’s solve the crossword in order to check the above reading. Click on the icon to start!
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Test. Click on the icon to start multiple choises exercise.
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Homework!
Create a table with names, acronyms and the characteristics of the main Sensors and Actuators in a modern car. For your assistance follow the
links below, but also search the web services. Assignment must be delivered next week!
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Additional video sources
https://www.youtube.com/watch?v=HkIfG8DCIV4 Sensors
https://www.youtube.com/watch?v=Fl3aD1qJrEg λ sensor
https://www.youtube.com/watch?v=sSuL58YEH-E MAF
https://www.youtube.com/watch?v=_vAtjLil5Y0 MAP
http://www.anaheimautomation.com/manuals/forms/stepper-motor-guide.php#sthash.thXEG9hg.dpbs Stepper motors
http://densoautoparts.com/fuel-injectors Injectors
https://www.facebook.com/MechanicsTips/videos/601495239999216/ how injectors work
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