Different types of automotive sensors and introduce the basics
Release Date：2013-12-10 00:00
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压力传感器、油量传感器和水温传感器到经历帮助控制汽车的动力系统(汽车传动系统的组成)及维持一定的空">Sensors
used in the 1960s auto ( automotive sensor applications ) only
from the initial oil pressure sensor , fuel sensor and temperature
sensor to help control the car through the power system ( consisting of
automotive driveline ) and maintain a certain air fuel
ratio sensor to control emissions and then applied to today's anti-lock
braking system and improved vehicle safety airbag sensor , the size of
automotive sensors has been growing. So, what does the car sensor type ? Xiaobian finishing by
collecting inion on the automotive sensor types and their related
knowledge to do a brief introduction .
Automotive
sensor type more, like we usually encounter automotive sensors in
general are: a temperature sensor ( cooling water temperature sensor
THW, intake air temperature sensor THA); flow sensor ( air flow sensor ,
fuel flow sensors ) ; intake air pressure sensor MAP ; throttle position sensor TPS; engine speed sensor ; speed sensor
SPD; crankshaft position sensor ( ignition timing sensor ) ; oxygen
sensor ; knock sensor (KNK); air flow sensor ;
Let us briefly explain some commonly used automotive sensors :
Air flow sensor
Intake
air flow sensor is converted into an electric air supplied to the
electronic control unit ) , a basic fuel injection signal is determined
as one . Depending
on the measuring principle, can be divided into rotary vane air flow
sensor Karman vortex air flow sensor tours , hot air flow sensor VG30E
engine and domestic passenger cars equipped with three peaks Tianjin
Volvo B230F engine ) and four kinds of hot-film air flow sensor types. The former two both volume flow type , after the mass flow type . At present, the use of hot air flow sensor and two kinds of hot-film air flow sensor . In
order to meet the requirements of ion of the mixed gas , air-fuel
ratio reaches the optimum value , we must engine intake air flow rate
for precise control . Here we introduce several common air flow sensor .
Oxygen Sensor
When
the oxygen content of the exhaust gas is too high , indicating that the
mixture is too thin, the oxygen sensor that outputs an electrical
signal to the ECU, let instruction injector fuel injection quantity
increases ; When the oxygen content of the exhaust gas is too low ,
indicating mixture
is too thick , the oxygen sensor imtely pass this inion to
the ECU, allowed to reduce the amount of fuel injection injector
instruction . Auto oxygen sensor is currently used mainly in the titanium
dioxide and zirconium dioxide oxygen sensor oxygen sensor two types of
sensors .
How it works: oxygen sensor installed in the engine exhaust tube , used to measure the oxygen content in the exhaust gas . It
is in accordance with the difference between the atmosphere and the
oxygen concentration of the exhaust gas to produce a battery emf . As shown , in the ceramic electrolyte , respectively, the outer sides to form an electrode coated with platinum . When
it is inserted into the exhaust pipe , the exhaust gas contacts the
outer surface , the inner surface of the atmospheric air . When a temperature above about 300 degrees , can be changed to ceramic electrolyte oxygen ion conductor . When
a lean mixture , that is, the excess air coefficient α> 1, the
oxygen concentration in the exhaust gas more bound oxygen concentration
inside and outside surfaces of the ceramic electrolyte is small , only
small voltage ; darker when the mixture , which is excess
air coefficient α < 1, the less oxygen content in the exhaust gas ,
accompanied by a large number of incomplete combustion such as CO,
hydrocarbons , etc. These ingredients may react with oxygen in the role
of a catalyst , exhaust gas consumption residual oxygen , the oxygen concentration in the outer surface of
the ceramic electrolyte tends to zero , thus making the oxygen
concentration difference between inside and outside the sudden increase
of the electrolyte , the sensor output voltage suddenly increases , its
value tends to 1V.
Throttle position sensor
( 1 ) switch type throttle position sensor
This is essentially a throttle position sensor switch , also called a throttle switch. This includes moving contact throttle position sensor , idle contact , full load contacts. Idle and full load using contacts to detect an idle state and the contact state of the engine heavy . Generally
referred to as the moving contact TL contacts, idle contact called IDL
contact, full load contacts called PSW contacts. As
can be seen from the chart, under the action of the throttle linkage
rod , the cam can be rotated along the movable contact of the moving cam
groove . This throttle position sensor structure is relatively simple, but its output is non- continuous.
When
the throttle is fully closed , the voltage applied to the terminals
from TL IDL terminal , then back to the electronic controller. When passing the signal through this pathway , the electronic controller is now understood fully closed throttle . When
the accelerator pedal is depressed , the opening degree of a throttle
valve in the above , the voltage from the terminal TL terminal PSW then
passed through the electronic controller . Electronic controllers understand, now open the throttle a certain angle.
( 2 ) linear throttle position sensor
Linear throttle position sensor mounted on the throttle , it can continuously detect the throttle opening . It mainly consists of a potentiometer and the throttle linkage , idle contact other components. The
movable contact of the potentiometer ( i.e., a throttle opening degree
output contact ) with the degree of opening of the throttle slide in the
resistor film , so that on the contact (TTA terminal ) to obtain the
throttle opening degree proportional to the linear voltage output. Figure . When
the throttle is fully closed , the other one with the throttle linkage
dynamic contact with IDL contact connected , idle sensor output signal . Linear voltage output from the throttle position signal after A / D conversion fed to the computer.
Pressure Sensor
( 1 ) capacitive pressure sensor
Capacitive
pressure sensor disposed in the cavity by the two movable piece (
resilient metal diaphragm ) , the two other fixed plate ( metal coating
on a flexible diaphragm on the concave glass ) , the output terminal and
the housing components. Form two capacitors in series between the two fixed pieces and movable pieces . When
force is applied to a flexible diaphragm intake pressure , the elastic
diaphragm displacement bound decreases with distance from a given piece ,
but with another set piece from the increase ( by a piece of paper can
be used to demonstrate ) . We
can see from the equation, the distance between the two metal electrode
plates is one of the important factors affecting capacitance , the
distance increases, the capacity reduced by the distance, the
capacitance increases . This
is caused by an amount of two sensing elements measuring parameters
equal , opposite change of the structure is called a differential
structure. If
the elastic diaphragm and the atmospheric pressure is placed between
the side ( upper cavity to atmosphere elastic diaphragm ) , is measured
by the gauge pressure ; if the elastic membrane is placed ( space
between the upper side of the elastic diaphragm and the vacuum pressure through the vacuum chamber ) , the measured absolute pressure.
( 2 ) the differential transformer intake pressure sensor
Differential pressure sensor is a magnetic sensor to open mutual inductors . Because of the two secondary coils connected in a differential configuration , it is also known a differential transmission.
When
the differential transformer primary winding power by alternating
excitation , its secondary coil induced electromotive force is generated
. As the secondary coil is connected as a differential , so the total output is the difference between the two coils EMF . When the core is not moving , the total output of zero ; when the
core moves , the output force varies linearly with the displacement of
the core .
Detection
and conversion differential transformer intake pressure sensor are:
changes in pressure into the displacement of the first transformer core
and core displacement by differential transmission and then converted
into an electrical signal output. This pressure sensor is mainly a vacuum bellows ( bellows ) , differential transmissions and other components. When
the pressure changes , the deion of the bellows , the core
to drive the differential transformer , as the displacement of the core
, i.e., the output terminal of the differential voltage generating
transformer , this voltage is supplied to ECU after processing the input
. If the voltage level is determined according to the time and make
the injector spray job, you can determine the basic fuel injection
quantity .
( 3 ) Intake semiconductor strain gauge pressure sensor
Intake semiconductor pressure sensor is the use of strain effects work.
The so-called strain effect , refers to as a conductor ,
semiconductor strain generated in the external force , the phenomenon of
resistance value changes .
Resistance
strain sensor chip is a chip resistor , which is a semiconductor
material when using the principle of the so-called piezoresistive effect
of stress , its resistance will occur at a certain load is applied
axially changing work .
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