Brothers, do you know the meaning of various automobile computer terminal numbers?

[Share] Automobile Computer An automobile computer is an electronic device that automatically processes the input signals of various sensors according to a predetermined program, and then outputs the signals to an actuator, thereby controlling the operation of the automobile.

Classification of automobile computers

At present, automobile computers have been widely used, such as body computers, engine computers, transmission computers, ABS computers and so on. Although the number and types of computers on different models are different, the general development trend is to use a main computer to process the input signals of most sensors and use some smaller electronic control units to control other systems.

Composition of automobile computer

The main part of an automobile computer is a single chip microcomputer, which is a circuit board integrated with a microprocessor (CPU), a memory and an input/output interface. Microprocessor is the core component of single chip microcomputer. The microprocessor converts the input analog signal into digital signal, compares it with the stored reference data, and calculates the output value. After power amplification, the output signal controls actuators, such as fuel injectors and relays. With the continuous improvement of the computing power and storage capacity of single chip microcomputer, the functions of automobile computer are also increasing.

Working process of automobile computer

(1) signal filtering and amplifying input circuit receives the input signals of sensors and other devices, and filters and amplifies the signals. The purpose of input signal amplification is to increase the signal to a level that can be recognized by the automobile computer. Some sensors, such as oxygen sensors, produce low-voltage signals less than 1V, and can only produce small current. This signal must be amplified before it is sent to the microprocessor of the computer. This amplification is completed by the amplifier circuit of the input chip in the computer.

(2) Analog-to-digital (A/D) conversion Because many sensors produce analog signals and microprocessors process digital signals, it is necessary to convert analog signals into digital signals, which is completed by the analog-to-digital converter in the computer input chip. The analog-to-digital converter continuously scans the analog input signal of the sensor at a fixed time interval, assigns a fixed value to the analog signal, and then converts the fixed value into a binary code. In some automobile computers, the input processing chip and microprocessor are integrated.

(3) The microprocessor calculates the preprocessed signal and sends the processed data to the output circuit. The output circuit amplifies the digital signal, and part of it is converted into analog signal to drive the actuator to work.

With the improvement of automobile electronization and automation, there will be more and more automobile computers, which will inevitably lead to more and more complicated body wiring harness. In order to realize the rapid transmission of information between multiple automobile computers, simplify the circuit and reduce the cost, it is necessary to connect automobile computers into a network system by using communication network technology. For example, the transmission needs to coordinate with the engine and automatically shift gears according to factors such as vehicle speed, engine speed and power load, so the transmission computer needs to obtain signals such as throttle position sensor, vehicle speed sensor, water temperature sensor and engine speed sensor, which will realize information transmission between the transmission computer and the engine computer. This work is usually done by CAN bus.

Characteristics of automobile computer

(1) Cars need to run in different roads and climatic conditions, and the working environment of on-board computers is poor, and they often have to bear the changes of vibration and temperature and humidity. The power supply voltage of automobile computer changes greatly, and it will also be interfered by electromagnetic waves inside and outside the car, so the automobile computer requires high reliability and durability of the environment.

(2) The automobile computer must have sufficient intelligence, self-diagnosis and detection capabilities, be able to find faults in the system in time, store fault codes, and inform the maintenance personnel of the parts where faults may occur, so as to facilitate maintenance. For example, the airbag must be opened in time, correctly and quickly at the critical moment, but most of the time the airbag is in standby state, so the airbag computer must have self-checking ability to continuously confirm whether the airbag system works normally.

(3) With a few exceptions, all automobile computers use 5V power supply to drive their sensors. In the electronics industry, 5V voltage is almost universally used as the standard for transmitting information. This voltage is high enough for transmission reliability, but low enough for the safety of computer chips. Moreover, the use of computer industry standard voltage will standardize and reduce the cost of electronic components for automobile manufacturers.

Maintenance of automobile computer

The internal circuit of automobile computer can be divided into two parts, namely, the conventional circuit including input, output and conversion circuits and the microprocessor. Conventional circuits mostly use common electronic components, which can be repaired if damaged. In the actual use process, most of the faults of automobile computers occur in conventional circuits. If you want to repair the car computer, you must first make sure that it is a computer fault, so as to avoid blind maintenance, causing unnecessary waste of time and other circuit failures.

(1) The usual method to judge whether the computer is damaged is that the computer can't output the control signal correctly to drive the actuator when the relevant sensor signals can be normally input into the computer. Although this sentence is simple, it needs a lot of detailed basic inspection work. For example, if the engine cannot be started, make sure that there is no frequency voltage on the fuel injector plug when it is started. Check that the relevant circuits are normal, and the starting signal can be input to the engine computer normally, but the computer does not output the driving signal to the injector, so it can be concluded that there is a fault inside the engine computer.

(2) Find the damaged component according to the circuit. According to the circuit diagram or the actual circuit trend, find the corresponding computer terminal connected with the fuel injector, and then use the on-off block of the digital multimeter to start from the determined computer terminal and search along the printed circuit of the computer until a transistor is found. This is because computers usually use high-power transistors to amplify execution signals to drive actuators, so most of these failures are caused by short circuits of transistors that act as switches.

(3) Measure the triode to determine the triode. The pin corresponding to the printed line is the collector of the triode, and the thinner printed line next to it is the base. The confirmation method is to plug in the porous plug of the engine computer, start the engine, connect the voltage block of the multimeter to the printing line to be confirmed, and display 5V as the base. Test triode with multimeter. If it is found that the forward and reverse resistance between the collector (C) and the base (B) is infinite, it means that the triode has been disconnected. If the resistance between the collector (C) and the emitter (E) is found to be zero, the triode has been broken down. In addition, other triodes and diodes connected near the triodes also need to be measured.

(4) There are roughly the following methods to determine the model of the triode: ① Model. Check the model of triode, and determine the matching domestic triode through the triode correspondence table. ② Resistance. The base of a triode is generally connected in series with a resistor, and the resistance value of the base is close to that of the original triode, and the resistance values of different colors are different. Because the base of the transistor is controlled by the current and the computer voltage is fixed, it is necessary to control the current with a resistor. Too much current will burn out the triode, and too little current will not trigger it. ③ measurement. Measure the characteristics of triode with diode measuring block of multimeter. According to the characteristics of triode, only the 1 pin should conduct in one direction relative to the other two pins. With this property, it can be determined that it is a triode. Only one pair of pins is conductive in one direction, and the conductive pin of the other two pins is the base of the triode.

(5) When welding the replacement transistor to the circuit board, pay attention to the minimum amount of solder to avoid overheating. After welding, use a multimeter to measure whether the pins are not connected.

(6) Test the maintenance effect. Connect the computer board to the body harness, start the engine to check whether the corresponding function is normal, and touch the triode with your hand at the same time. Some heat is normal, and when it is hot, there is something wrong. Observe whether the fault light is on, and carry out a road test for a certain mileage.

Taking the fuel injector circuit controlled by engine computer as an example, the process of engine computer maintenance is briefly explained.

(1) Fuel injector power supply circuit The fuel injector circuit is divided into two parts: power supply circuit and engine computer control circuit. The power supply of the fuel injector is mostly provided by the fuel injection relay, that is, after the ignition switch is turned on, the fuel injection relay acts and the battery voltage reaches the fuel injector. At this time, it waits for the control signal of the engine computer to cooperate with the work required by the engine.

(2) Engine computer control circuit The engine computer calculates according to the load, rotating speed and various correction signals, the output circuit outputs the fuel injector pulse signal, and the driving circuit amplifies the voltage signal and then connects it to the base (b) of the NPN power transistor, so that the triode can switch the pulse frequency, that is, the electromagnetic coil of the fuel injector is turned on and off.

(3) Fault Analysis of the Fuel Injector Circuit The control circuit that performs the switching action of the fuel injector is a triode that controls the grounding loop of the fuel injector coil. The collector (C) of the triode is connected to the fuel injector, and the emitter (E) is grounded. If the C-pole and E-pole are short-circuited, the fuel injector will always inject fuel after the ignition switch is turned on. If the C pole is open, it will make the fuel injector unable to complete the grounding circuit, resulting in the fuel injector unable to inject fuel. In addition, if the protection diode connected in parallel with the C pole of the triode is short-circuited, the phenomenon that the fuel injector keeps injecting fuel will also occur.

(4) Tools such as digital multimeter, oscilloscope or LED test lamp can be used to detect the fuel injector circuit. It is forbidden to plug or unplug the wiring harness with electricity, or use pointer multimeter or high-power test lamp, so as not to cause instantaneous high current to damage the internal triode of the engine computer.

Connect the LED test light to the two sockets of the fuel injector plug and turn on the ignition switch. If the LED light is always on, it means that the C and E poles of the triode are short-circuited; If the LED light is off, start the engine. If the LED light is still off, it means that the C and E poles of the triode are open.

Automobile computer manufacturer

The main manufacturers of automotive computers in the world are multinational companies such as Delphi, Bosch, Siemens VDO and Denso, and their products occupy a large proportion in the vehicle supporting market and parts market. Because of the supporting system, their products occupy an important position in the supporting system of domestic automobiles.

Major automobile manufacturers have entered China one after another, which has also driven the huge parts market in China. Many multinational parts companies have fully realized the huge potential of the China market. They have established wholly-owned or joint ventures in China and set up a technology research and development center in China to better provide supporting products according to the requirements of China automobile manufacturers. Relatively speaking, domestic auto parts manufacturers are weak in R&D and automobile computer production, and the matching rate of their products is also very low, so their position in the automobile computer market is not optimistic.