sensors , LE THANH PHUC

Potentiometer: Vane type airflow meterThe vane type air flow meter is located in theair induction system inlet pipe between theair cleaner and the throttle body... Potentiometer: Vane ty

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SENSORS

Le Thanh Phuc

Faculty of Automotive Engineering

Email: thanhphucckd@gmail.com

University of Technical Education

Ho Chi Minh City

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Thermistors are commonly used to

measure the temperature of liquids and

ambient air

A thermistor is a solid-state variable

resistor made from a semiconductor material that have very reproducible resistance

verses temperature properties

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There are two types of thermistors:

negative temperature coefficient (NTC)

thermistors and positive temperature

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Thermistors: Water Temperature Sensor

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The water temperature sensor is typically

located near the cylinder head water

outlet

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Position and Motion Detection Sensors

Many electronic systems require input data concerning position, motion, and speed

Most motion and speed sensors use a

magnet as the sensing element or sensed

target to detect rotational or linear speed

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A common position sensor used to monitor linear or rotary motion is the potentiometer

A potentiometer is a voltage divider that

provides a variable DC voltage reading to the computer

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Potentiometer: Vane type airflow meter

The vane type air flow meter is located in theair induction system inlet pipe between theair cleaner and the throttle body

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The potentiometer converts the mechanical movement of the measuring plate into a

variable voltage signal

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Movement of the measuring plate and

the analog voltage signal produced by thissensor are proportional to the volume of airentering the intake manifold

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Karman airflow meter

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Intake air flow reacting against the vortex

generator creates a swirling effect to the air

downstream, very similar to the wake created in the water after a boat passes

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Mass Air Flow (MAF) Sensors

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The Mass Air Flow Sensors converts the amount of air drawn into the engine into a voltage

signal.

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The air flow sensor is located directly in the

intake air stream, between the air

cleaner and throttle body where it can measure incoming air

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Wheatstone Bridges

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A Wheatstone bridge is nothing more than two simple series circuits connected in parallel across a power supply

When all four resistors have the same value, the bridge is balanced and the voltage sensor will indicate a value of 0 volts

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The thermistor measures the temperature of the incoming air

The hot wire is maintained at a constant

temperature in relation to the thermistor by the electronic control circuit

An increase in air flow will cause the hot wire

to lose heat faster and the electronic control

circuitry will compensate by sending more

current through the wire

The electronic control circuit simultaneously measures the current flow and puts out a

voltage signal (VG) in proportion to current

flow

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Manifold Absolute Pressure (MAP) Sensor

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In the Manifold Absolute Pressure (MAP)

sensor there is a silicon chip mounted inside a

reference chamber On one side of the chip is a reference pressure On the other side is the

pressure to be measured

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Magnetic Pulse Generator

The components of the pulse generator are:

1 A timing disc that is attached to the

rotating shaft or cable The number of teeth

on the timing disc is determined by the

manufacturer and depends on application

2 A pickup coil consists of a permanent

magnet that is wound around by fine wire

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Position/speed sensors provide information to

the ECM about the position of a component, thespeed of a component, and the change in speed

of a component

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This system consists of a gear (reluctor wheel), that is mounted on the distributor shaft, has a

number of teeth equaled to number of engine

cylinders, permanent magnet and pick up coil

wrapped around the magnet

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Hall-Effect Sensors

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Based on the principle that if a current is

allowed to flow through thin conducting

material that is exposed to a magnetic

field, another voltage is produced

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Switch Inputs

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Switches are simplest of all input devices

The computer monitors the two states of

the switch by measuring the voltage on the

sense circuit

There are two types of voltage sensing

circuits used with switches; the pull-down

circuit and the pull-up circuit

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Switch Inputs

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Switch Inputs: Stop switch

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