Auto Sensors Category and Work Rule

How many kind Auto Sensors , Car sensor. and how they work.

Vehicle sensors are the input devices of the automobile computer system. It converts various operating conditions of the automobile, such as vehicle speed, temperature of various media, engine operating conditions, etc., into electrical signals and sends them to the computer so that the engine is at its best Working status. There are many automotive sensors. When judging the fault of the sensor, you should not only consider the sensor itself, but the entire circuit where the fault occurs. Therefore, when troubleshooting, in addition to checking the sensor, the wiring harness, connectors, and related circuits between the sensor and the electronic control unit should also be checked.
Chinese name automotive sensor application automotive type input device field electronic equipment
table of Contents
1 Detailed introduction
2 Test characteristics
▪ Test similarity
▪ Test equipment
▪ Other requirements
3 Common types
▪ Odometer
▪ Engine oil pressure
▪ Water temperature sensor
▪ Air flow
▪ ABS sensor
▪ Airbag
▪ Gas concentration
▪ Position and speed
▪ Speed ​​sensor
4 Basic characteristics
▪ Sensor characteristics
▪ Working mechanism
5 categories
6 Development history
7 Market conditions
8 Application status
▪ Application
▪ Temperature sensor
▪ Pressure sensor
▪ Flow sensor
▪ Position and speed
▪ Gas concentration
▪ Knock sensor
▪ Radar sensor
▪ Body application
▪ Chassis application
▪ Application status
▪ For navigation system
▪ Automatic transmission
9 Application
10 Domestic development
▪ Market
▪ Importance
▪ Domestic sensors
11 Development Trend
12 Technology Development
13 How to detect
Detailed introductionedit
Car sensor
Car sensor (4 photos)
One of the characteristics of the development of automobile technology is that more and more components adopt electronic control. According to the function of the sensor, it can be classified into sensors that measure temperature, pressure, flow, position, gas concentration, speed, brightness, dry humidity, distance and other functions. They each perform their duties. Once a sensor fails, the corresponding device works It will be abnormal or even not working. Therefore, the role of sensors in automobiles is very important.
Automotive sensors used to be used solely on engines, but have been extended to chassis, body and light electrical systems. There are more than 100 kinds of sensors used in these systems. Among the wide variety of sensors, the common ones are:
Intake pressure sensor: It reflects the change of absolute pressure in the intake manifold, and provides a reference signal for calculating the fuel injection duration to the ECU (engine electronic control unit);
Air flow meter: Measure the amount of air sucked by the engine and provide it to ECU as a reference signal of fuel injection time;
Throttle position sensor: Measure the angle of throttle opening and provide it to ECU as a reference signal for fuel cutoff, fuel/air ratio control, and ignition advance angle correction;
Crankshaft position sensor: detects the crankshaft and engine speed, and provides it to the ECU as a reference signal for determining the ignition timing and working sequence;
Oxygen sensor: it detects the oxygen concentration in the exhaust gas and provides it to the ECU as a reference signal to control the fuel/air ratio near the optimal value (theoretical value);
Car sensor
Intake air temperature sensor: detects the intake air temperature and provides it to the ECU as a basis for calculating air density;
Coolant temperature sensor: detects the temperature of the coolant and provides engine temperature information to the ECU;
Knock sensor: It is installed on the cylinder block to specifically detect the engine’s knocking situation, and is provided to the ECU to adjust the ignition advance angle according to the signal.
These sensors are mainly used in transmission, steering, suspension and ABS.
Transmission: There are vehicle speed sensors, temperature sensors, shaft speed sensors, pressure sensors, etc., and direction sensors include rotation angle sensors, torque sensors, and hydraulic sensors;
Suspension: vehicle speed sensor, acceleration sensor, vehicle height sensor, roll angle sensor, rotation angle sensor, etc.;
Let’s get to know the main sensors on the car.
The air flow sensor converts the inhaled air into an electric signal and sends it to the electronic control unit (ECU) as one of the basic signals for determining fuel injection. According to different measurement principles, it can be divided into four types: rotary vane air flow sensor, Karman vortex air flow sensor, hot wire air flow sensor and hot film air flow sensor. The first two are volume flow type, and the latter two are mass flow type. Mainly use two kinds of hot wire air flow sensor and hot film air flow sensor.
The intake pressure sensor can measure the absolute pressure in the intake manifold according to the load state of the engine, and convert it into an electrical signal and a speed signal and send it to the computer as a basis for determining the basic fuel injection volume of the injector. The semiconductor piezoresistive intake pressure sensor is widely used.
The throttle position sensor is installed on the throttle to detect the opening of the throttle. It is linked with the throttle through a lever mechanism to reflect the different operating conditions of the engine. This sensor can detect the different working conditions of the engine and input it into the electronic control unit (ECU) to control different fuel injection quantities. It has three types: switch contact type throttle position sensor, linear variable resistance type throttle position sensor, and integrated throttle position sensor.

Crankshaft position sensor
Crankshaft position sensor, also called crankshaft angle sensor, is the most important sensor in the computer-controlled ignition system. Its function is to detect top dead center signal, crankshaft angle signal and engine speed signal, and input it into the computer so that the computer can press cylinders The best ignition timing command is issued in the ignition sequence. There are three types of crankshaft position sensors: electromagnetic pulse type crankshaft position sensor, Hall effect type crankshaft position sensor, photoelectric effect type crankshaft position sensor. Different types of crankshaft position sensors have different control methods and control accuracy. The crankshaft position sensor is generally installed on the side of the crankshaft pulley or sprocket, and some are installed on the front end of the camshaft, and some are installed on the distributor.
The knock sensor is installed on the engine block to monitor the engine’s knock at any time. There are two types of resonance type and non-resonance type.
Test features
Diversity and rapid change of tested objects
The sensor types commonly used in automobiles include wheel speed sensors, crankshaft/camshaft position sensors, temperature sensors, pressure sensors, knock sensors, etc. In view of the endless stream of models, each sensor with the same function has various differences in appearance, coupled with the increasingly demanding requirements of measurement indicators and production environment, making the traditional single test bench unable to take into account such diverse Sensor production.
Test proximity
In actual production, the test content of different sensors has a certain similarity. Because from the principle of testing, automotive sensors are mainly divided into active/passive, temperature, and pressure sensors. In other words, for different sensors, as long as the test principle is the same, it means that their test instruments and other equipment are also the same.
Test Equipment
Automobile sensor production lines require the use of economical, efficient, automatic, and flexible test equipment, and they must have the characteristics of high automation, high efficiency, high productivity, and high reliability. Sensor manufacturers hope that after a one-time investment, the test equipment itself can be continuously expanded to effectively support the latest products and higher performance index requirements, thereby ensuring the effectiveness of equipment capital investment.
other requirements
In order to ensure production quality, the equipment needs to have certain production process statistics capabilities and help reduce the problem of reduced production quality due to human factors. Integration and intelligence are the development trend of automotive sensors. If only the final test is carried out, it is too late to find the problem, so the test will often interact with the production process. In this way, on the one hand, the test equipment is required to be well connected with other equipment on the production line, and on the other hand, information and data sharing between equipment can be realized.
Common types

Odometer sensor
The sensor on the differential or the half shaft can sense the number of turns. Generally, Hall and photoelectric are used to detect the signal. Its purpose is to use the odometer to effectively analyze and judge the driving speed and mileage of the car. Because the angular velocities of the axle shaft and the wheel are equal, the radius of the tire is known and calculated directly by the mileage parameter. Two bearings are designed on the drive shaft, which greatly reduces the torque during operation, reduces friction, and enhances the service life; the original dynamic detection signal is changed to the gear operation detection signal; the original direct-plug vertical gearbox Change to chamfered interface gearbox. The odometer sensor plug is generally on the gearbox, some can be seen by opening the engine cover, and some need to be operated in the trench.
hydraulics pressure
Refers to a micro-electromechanical system that integrates micro-sensors, actuators, signal processing and control circuits, interface circuits, communications and power supplies. Commonly used are silicon piezoresistive and silicon capacitive, both of which are micromechanical electronic sensors generated on silicon wafers. In general, we use the oil pressure sensor to detect how much oil is in the car’s oil, and convert the detected signal into a signal we can understand, reminding us how much oil is left, or how far we can go, It even reminds the car that it needs oil.
Water temperature sensor
Inside it is a semiconductor thermistor, the lower the temperature, the greater the resistance; on the contrary, the smaller the resistance, it is installed on the water jacket of the engine block or cylinder head and is in direct contact with the cooling water. So as to get the temperature of engine cooling water. The electronic control unit measures the temperature of the engine cooling water according to this change. The lower the temperature, the greater the resistance; otherwise, the smaller the resistance. The electronic control unit measures the temperature of the engine’s cooling water according to this change, which is used as a correction number for fuel injection and ignition timing. That is, we can understand the running state of the car, stop or movement, or how long the movement is from the temperature of the engine water temperature.
Air flow

Air flow sensor
Its function is to detect the size of the engine’s intake air volume, and convert the intake air volume information into electrical signal output, and send it to the ECU. We know that the driving of a car requires an ignition device to ignite to obtain a forward impulse. Therefore, the amount of charge is the basis for the ECU to calculate the fuel injection time and fuel injection volume and ignition time required by the ignition device when the car is ignited. Its function is to allow us to better accelerate and decelerate the car.
ABS sensor
Beside the brake piston (the caliper holding the brake disc, inside is the brake piston), the ABS job is to ensure that the brake piston and the brake disc are not stuck, and that they are on the edge of sliding friction and static friction. Most of the vehicle speed is monitored by inductive sensors. The ABS sensor outputs a set of quasi-sinusoidal alternating current signals through the action of the ring gear that rotates with the wheels. The frequency and amplitude are related to the wheel speed. The output signal is transmitted to the ABS electronic control unit (ECU ) To realize real-time monitoring of wheel speed.
airbag
Airbag sensor
Airbag sensor
Also known as collision sensor, according to different purposes, it is divided into trigger collision sensor and protection collision sensor. The trigger collision type is used to detect the acceleration change during the collision and transmit the collision signal to the airbag computer as the trigger signal of the airbag computer; the protective collision type is connected in series with the trigger collision type to prevent the airbag from accidentally exploding.
Gas concentration
Mainly used to detect the gas and exhaust emissions in the car body. Among them, the most important is the oxygen sensor, which detects the oxygen content in the car exhaust, determines the air-fuel ratio according to the oxygen concentration in the exhaust, and sends a feedback signal to the microcomputer control device to control the air-fuel ratio to converge to the theoretical value. When the air-fuel ratio becomes higher and the oxygen concentration in the exhaust gas increases, the output voltage of the oxygen sensor decreases; when the air-fuel ratio becomes lower and the oxygen concentration in the exhaust gas decreases, the output voltage increases. The electronic control unit recognizes this sudden change signal and corrects the fuel injection volume, thereby adjusting the air-fuel ratio accordingly to make it change near the ideal air-fuel ratio.
Position and speed
Mainly used to detect engine crankshaft angle, engine speed, throttle opening, vehicle speed detection, automobile acceleration detection, automobile deceleration detection, etc., provide reference point signals for ignition timing and fuel injection timing, and provide engine speed signals. The position and speed sensors used in automobiles mainly include alternator type, magnetoresistive type, Hall effect type, reed switch type, optical type, and semiconductor magnetic transistor type.
speed sensor
speed sensor
speed sensor
Speed ​​sensor is a more important sensor for electric vehicles, and it is also a sensor with more applications. In terms of its definition, the speed sensor is mainly used to measure the speed of the sensor, divided into speed sensor, vehicle speed sensor, wheel speed sensor and so on.
Rotational speed sensors are mainly used to detect the rotation speed of electric vehicles. There are three commonly used speed sensors, namely electromagnetic induction speed sensors, photoelectric induction speed sensors, and Hall-effect speed sensors, all of which use non-contact measurement principles to enhance detection safety and improve detection accuracy.
Vehicle speed sensors are used to measure the speed of electric vehicles. The vehicle speed sensor signal is mainly used for the speedometer display of the dashboard and the control of the engine idling speed and the acceleration of the electric vehicle. At present, most of the speedometers on electric vehicles in our country are measured by converting the rotation speed of the car tires into the car speed. In the case of car braking or skidding, as well as changes in the outer circumference of the tire due to new and old tires, friction, road surface, tire pressure, etc., the error will be too large, or even unable to work. Vehicle speed sensors mainly include electromagnetic induction, photoelectric Type, variable reluctance type and Hall type concentration. Electromagnetic induction and Hall-type speed sensors are commonly used in electric vehicles.
Basic characteristics
Sensor characteristics
Sensors refer to devices or devices that can sense specified physical quantities and convert them into usable input signals according to certain rules. Simply put, a sensor is a device that converts non-electricity into electricity.
Sensors are usually composed of three parts: sensitive components, conversion components and measurement circuits.
1) Sensitive element refers to the part that can directly feel (or respond) to the measurement, that is, the sensitive element that is measured through the sensor is converted into non-electricity or other quantities that have a definite relationship with the measurement.
2) The conversion element converts the above non-electricity into electrical parameters.
3) The function of the measuring circuit is to convert the electrical parameters input by the conversion element into a measurable amount of voltage, current or frequency after processing, so as to display, record, control and process the part.
Sensor’s static characteristic parameter index
⒈Sensitivity
Sensitivity refers to the ratio of the sensor output y to the input x at steady state, or the ratio of the increment of the output y to the increment of the input x, expressed as k
k=dY/dX
⒉Resolution
The smallest amount of change that the sensor can detect within the specified measurement range is called the resolution.
⒊Measuring range and measuring range
Within the allowable error limit, the range from the lower limit to the upper limit of the measured value is called the measurement range.
⒋Linearity (non-linear error)
Under specified conditions, the percentage of the maximum deviation between the sensor calibration curve and the fitted straight line and the full-scale output value is called linearity or nonlinear error.
⒌Hysteresis
Hysteresis refers to the degree of inconsistency between the positive travel characteristics and the reverse travel characteristics of the sensor under the same working conditions.
⒍Repeatability
Repeatability refers to the inconsistency of the characteristic curve obtained by continuously changing the input quantity in the same direction over the entire measurement range under the same working conditions.
⒎Zero drift and temperature drift
When the sensor has no input or the input is another value, at regular intervals, the percentage of the maximum deviation of the input value from the original display value and the full range is zero drift. And every time the temperature rises by 1℃, the maximum deviation of the sensor output value and the percentage of full scale is called temperature drift.
Working mechanism
A) Magnetoelectric effect
According to Faraday electromagnetic induction

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