ABS的组成和工作原理（The composition and working principle of ABS）

ABS的组成和工作原理（The composition and working principle of ABS） ABS的组成和工作原理(The composition and working principle of ABS) The composition and working principle of ABS Usually, ABS is composed of wheel speed sensor, ABS electronic control unit, braking pressure regulating device and braking control circuit on the basis of common braking system. In the process of braking, ABS electronic control unit (ECU) 3 continuously from sensors 1 and 5 get the wheel speed signal, and then processed to analyze whether the wheel is about to lock slip. If there is no wheel about locking slip, the brake pressure regulating device 2 is not involved in the work, the brake master cylinder and the 7 wheel brake cylinder 9 is in the wheel brake cylinder pressures continue to increase, the ABS braking process of pressurized state. If the control unit judged a wheel (assuming the left front wheel) is locked to slip, it brake pressure regulator ordered off the brake master cylinder and the left front wheel brake cylinder of the channel, so that no longer increases left front wheel brake cylinder pressure, the ABS process of braking pressure state. If the control unit judges that the left front still tend to slip locking state, it is to the brake pressure regulating device sends a command, open the left front wheel brake cylinder and a liquid storage chamber or accumulator (not shown in the figure) of the channel, the left front wheel brake cylinder pressure in the braking process is reduced, ABS in the vacuum state The vehicle speed sensor speed sensor for the detection of electric vehicle speed control computer with the input signal to control the engine idle speed, torque converter automatic transmission lock and other functions of automatic transmission shift and engine cooling fan opening and closing and cruise and other. The output signal of the speed sensor can be magnetoelectric AC signal, can also be a Holzer type digital signal or photoelectric digital signal, speed sensors are usually installed in the drive axle or the transmission housing, the speed sensor signal line is usually installed in the shielding casing, which is in order to eliminate the electromagnetic voltage line of fire and car phone or other electronic devices and RF interference, to ensure the electronic communication without interruption, to prevent poor or other problems in the automobile driving performance, magnetoelectric and photoelectric sensor is the most widely used two kinds of speed sensor, in Europe, North America and Asia various automobiles more widely used magnetoelectric sensor to speed (VSS), crank angle (CKP) and cam angle (CMP) control at the same time, you can also use it to feel the speed and other rotating parts Place signals, such as compressors, clutches, etc.. 1) magnetoelectric speed sensor, magnetoelectric speed sensor is an analog AC signal generator, which produces alternating current signals, usually composed of two terminals with magnetic cores and coils. The two coil terminals are terminals of the sensor output. When the rotating ring made of iron (sometimes referred to as the magnetic pulley) rotates through the sensor, the coil generates alternating voltage signals. Each of the gears on the magnetic pulley will produce a series of pulses corresponding to the same shape. The amplitude of the output signal (peak to peak voltage) is proportional to the speed of the magnetic pulley, and the frequency of the signal is expressed in terms of the speed of the magnetic pulley. The air gap between the sensor core and the magnetic pulley has a great effect on the amplitude of the input signal of the sensor. If one or more teeth are removed from the magnetic pulley, a synchronous pulse can be generated to determine the position of the tdc. This will cause the frequency of the output signal and the output signal amplitude changes in tooth reduction will change, the engine control computer or ignition module is on the synchronous pulse signal to determine the trigger electric fire time or fuel injection time. The test step can drive the wheel of the system to simulate the driving conditions, and also can lengthen the test line of the automobile oscillograph and test it while driving. After the wheel turns, the waveform signal starts to jump up and down on the zero neutral line at the center of the oscilloscope, and gets higher and higher with the increase of the speed. The waveform display is very similar to the example, which is recorded at a speed of about 30 miles per hour, and does not look like an AC waveform, The waveform generated by the speed sensor is very similar to the shape of the waveform of the crankshaft and camshaft sensors. In general, the jump of the waveform on the zero volt line is very symmetrical, and the amplitude of the signal of the speed sensor increases with the speed. The higher the speed, the higher the amplitude of the waveform, and the increase in speed, waveform frequency will also increase, the oscilloscope will show a lot of waveform oscillation. The key dimensions such as amplitude, frequency, and shape are determined to be correct, repeatable, regular, predictable. This refers to the peak amplitude of the normal time, two pulse shape is unchanged, unchanging and predictable, uneven peak is caused by the magnetic core and the magnetic wheel collide sensor, which could be a bushing or transmission components of the sensor is not caused by the loss of the peak is round, the shortcomings of the magnetic damage group the wheel. Different types of sensors, the waveform of the peak voltage and the shape of a slight difference, because the sensor is a coil, so the fault is related to temperature, in most cases the waveform will become much shorter, the deformation is also great, but may also set the trouble code (DTC), the fault on the oscilloscope display shake the harness, which should further determine the magnetoelectric sensor is the cause of the fault, the common faults of the speed sensor signal output is no signal, but if the car is straight line waveform straight, then you should check the oscilloscope and the sensor line, there is no ground for determining circuit, confirmation parts can be rotated (plastic gears have killed) confirm the sensor air gap is normal, and then determine the sensor. 2) Holzer effect Holzer type speed sensor sensor (switch) in automotive applications is very special, this is mainly due to the transmission of space around the conflict, Holzer effect sensor is a solid sensor, they are mainly used in crank and camshaft position, switch for ignition and fuel injection circuit, it is also used to control rotor position and speed control circuit in other computer. Holzer effect sensor or switch, consisting of an almost completely closed magnetic circuit includes a permanent magnet and magnetic pole, a magnetic rotor blade passes through the air gap between the magnet and the magnetic pole, the blade on the rotor window allowed through the magnetic field is not affected by the Holzer effect and reach the sensor, but not part of the window therefore, the rotor magnetic field interruption, window function is to switch magnetic field, the Holzer effect as the same switch open or close, this is some car manufacturers will Holzer effect sensor and other similar electronic devices that switch the reason for Holzer, the component is actually a switching device, and it is the key part of Holzer the effect of sensor. The test step can drive the wheel top to simulate the running state, or the automobile oscilloscope test line can be extended to carry on the running test. The waveform when the wheel begins to rotate, the Holzer sensor began to produce a series of signals, pulse number will increase with the increase of speed, and legend alike, which is about 30 miles per hour when recording, the pulse signal frequency speed sensor with the speed increase, but the position of the duty ratio keep constant at any speed. The higher the speed sensor, the more waveform pulses on the oscilloscope. Confirmation from a pulse to another pulse amplitude, frequency and shape is consistent, that is to say cuts usually equal to the supply voltage of the sensor, two pulse interval, the same shape, and expected the same. Determine the frequency of the waveform and speed synchronization, and the duty cycle must not change, but also observe the following: observe the consistency of the waveform, check the top of the waveform and the sharp corners at the bottom. Observe the amplitude consistency: the waveform height should be equal because the supply voltage to the sensor is constant. Some examples show that the bottom or top of the waveform has a gap or irregularity. The key point here is that the stability of the waveform remains unchanged. If the waveform is too high to the ground, it shows that the resistance is too high or the sensor is not grounded properly. To observe the abnormal waveform caused by the generation of traffic performance problems and the occurrence of fault codes, it is possible to determine the signal problems directly related to the customer's failure or driving performance and the root cause of the malfunction. Although the Holzer effect sensors are generally designed to operate at temperatures as high as 150 degrees Celsius, their work is still subject to temperature, and many of the Holzer effect sensors will fail at certain temperatures (cold or heat). If the oscilloscope shows that the waveform is abnormal, check the disturbed line or connect the poor wire harness, check the oscilloscope and wiring, and determine the relevant components to rotate properly (such as: output shaft, sensor shaft, etc.). When the oscilloscope fails, shake the wiring harness, which provides further judgment to verify that the Holzer effect sensor is the root cause of the failure. 3) photoelectric speed sensor photoelectric speed sensor is photoelectric semiconductor sensor solid, comprising a rotary table with a hole in the two optical fiber conductor, a light-emitting diode, a photoelectric triode as the light sensor tube. An amplifier based on a photoelectric triode that provides sufficient power for an engine, a control computer, or an ignition module. A photoelectric triode and an amplifier generate a digital output signal (switching pulse). The light emitting diode passes through the hole on the turntable to light the photodiode to realize the transmission and reception of light. The intermittent holes on the turntable can switch on and off the light source on the photoelectric triode, and then trigger the photoelectric triode and amplifier to switch on or off the output signal as if the switch is on. From the oscilloscope observation and Holzer method of photoelectric speed sensor output waveform type speed sensor is exactly the same as the photoelectric sensor has a weakness that they on oil or light passing through the turntable in stolen goods is very sensitive to interference, so the functional element of photoelectric sensor is often designed to seal well, but the damage to the distributor or seal container in use will make the oil or dirt into sensitive areas, this will cause the driving performance problems and generate fault codes. The bright ABS lamp on you, may be the following causes: ABS speed sensor is mud, mud and other pollution sources covering, affect the speed sensor signal corresponding to the ABS computer, can not determine speed, can not determine the slip ratio of the wheel, and then can't make corresponding action instructions to adjust the brake; at this time as long as clean the dirt on the vehicle speed sensor, speed sensor and signal gap adjusting ring gear, can be restored to normal; the damage speed sensor is the most common cause of ABS in light of reason, which must then be replaced; there is the line between the loose connection system, ABS relay caused by poor contact and bad signal the malfunction in the system. The most common is the speed sensor cable loosening caused by fault, the fault memory in the ABS computer in this case will show the speed sensor signal is bad; you wash the car after the lights went out should be the speed sensor is dirty or caused by problems My Landry traveling near 6WKM, but some time ago, in the course of normal driving suddenly found ABS and handbrake lights on at the same time, the information store and query 4S friends "Elantra ABS lights and brake fault lights on the Internet, this is a common problem that the Elantra, KIA car, the reason is the generator the voltage regulator is broken, the failure occurs, the output voltage is above 17V, very easy to burn the lamp, and under normal circumstances is about 14V. The Internet also saw a lot of friends complain Beijing Hyundai Elantra, requirements of recall, because the problem is that individual design problem of the generator, but also in foreign website also found no centralized fault phenomenon, if the fault occurs in the running process of the key circuit and burned cars, it is hard to say what will happen serious accident. I have made a complaint on the quality network of China. I strongly recommend that all users who have similar faults send complaints to the following websites and ask for the modern recall vehicles in Beijing.