Statistics show that the share of electrical equipment accounts for about 25% of all vehicle faults arising in the process of operation. The condition of the ignition system significantly affects the operation of the engine. Due to the wear of its components, loosening of joints, erosion of contacts worsens the start of the engine, increasing fuel consumption, loss of power, reduced service life of the battery and increases the toxicity of exhaust gases. For example, disruption of the normal operation of centrifugal or vacuum regulator ignition timing causes an increase in fuel consumption by 6...8 %; one idle spark of the four - power reduced to 30 %; the delay of ignition timing by 5...8° against the norms reduces the effective power of the engine 8...12 %.
For diagnosing created special stands. One of the most common oscilloscope is a device for testing engines "Alcon S-200" produced by Hungary. With the help of this device can detect failures of the primary and secondary circuits of ignition systems by assessing the waveforms of voltages, measure the angle of the closed state of the breaker contacts in the range from 36 to 90°, the ignition timing from 0 to 60°, the peak voltage in the primary circuit 40 and In the secondary to 40 kV, measure the shaft speed of the engine to 10000 min-I, and to assess the difference in the power developed by the cylinders.
Structural scheme of the device "Alcon S-200" is shown in Fig. 1 in the text. The analyzed signals from the distributor of the car are removed from inductive and capacitive sensors Ul, U2.
Fig.1 (click to enlarge)
After limiting and synchronization with the rotation speed of the shaft of the distributor signals through the switch enter the electronic switch. This received input signals of the tachometer and gauges ignition timing. The operation of the electronic switch synchronizes the sawtooth generator. The result on the screen of a cathode-ray tube in between the analog image signal is reproduced, the frequency of rotation and the angle of an advancing of ignition in the form of a vertically moving labels.
When measuring the amplitude of the breakdown voltage on the spark plugs sawtooth generator generates a sweep signal for the horizontal deflection of the beam. In addition, its functions include control of the generator speed signal, which is necessary to create bitmaps. The generator speed signal generates pulses to control the blanking of the beam in the measurement of the difference in the capacities of the cylinders. In this case, the screen displays a bitmap image of the analog signal in the primary or the secondary circuit of the ignition system.
After clicking the button automatic switch-off of the cylinders on the screen, disappear the waveform of the ignition system of each of the cylinders and changing the rotational speed of the motor shaft, which can be monitored by the tachometer scale on the right side of the image. Readings outside the acceptable, indicate malfunction of the ignition system.
The signal from the tachometer unit is supplied to the measuring of the ignition timing (voltage-frequency), which, in turn, provides the strobe signal. The voltage necessary for the operation of the CRT, generates the power supply; it also performs the function of blanking blanking scanner, receiving the signals from the generator, saw-tooth voltage and the electronic switch.
In recent times, increases the production of specialized compact portable devices. A typical representative of this class of devices is the so-called measuring bag "Alcon S-320" (Hungary) for the diagnosis of vehicles. The minimum number of connecting cables and multi inductive probe, which allows to determine the state of the diodes and coils of the generator, to a great extent facilitates the measurements. Modern exterior design, small dimensions and weight (6 kg), easy maintenance provide quick and accurate execution of diagnostic tests.
Longstanding business relations, our foreign trade organizations with the Austrian firm "SIMA und Klein". It supplies motor vehicles and service enterprises diagnostic equipment, devices for rapid battery charging, etc.
The latest model of the firm", the Microcomputer of the motor-tester 1212". Unlike previous models, this widely used microprocessor technology, applied digit typer device. The device is designed for three main modes: start-movement-analysis of the cylinders. On the analog display shows relevant information about the order of work performed, is stored in ROM. Moreover, the language in which the information is displayed on the display can be easily changed by replacing the entire single chip. The digital display is designed for comparing the actual measured values from a table stored in a storage device. If the operator is inconvenient to go to the dashboard, it is possible to transfer the device to another mode with the remote control.
The share of road transport pollution of large cities is $ 30.. .40 %, with most of the harmful emissions - carbon monoxide. The contents of this extremely harmful substances in the exhaust gases of vehicles with gasoline engine is regulated by GOST and should not exceed 1.5...3.5 percent.
In the conditions of service stations the amount of toxic components is determined by means of gas analyzers. One such device is the sensor In-fruit-8T" production GDR, the device which is shown schematically in Fig. 2.
Fig.2
Infrared radiation from two incandescent spirals 1 (included in the collector circuit of power transistor of the power supply unit) is focused by a parabolic mirror 2 along the camera comparisons 3 and the working chamber 4, respectively. The first nitrogen-filled, virtually no absorbing IR radiation. In the same working chamber, through which blow exhaust gases from the engine, they absorb part of the spectrum components. Both cameras closed ends with filter, transparent to the infrared rays. Under the action of radiation, the air in the cavities of the receiver 7 is divided by a partition 5, is heated in different ways. The pressure difference causes the partition to bend. It is a capacitive pressure sensor.
Working in conjunction with the electronic control unit 6, the sensor generates a signal which is a function of the percentage of carbon monoxide. After amplification, the signal is sent to the indicator pointer instrument 9, showing the content of carbon monoxide, and the recorder 8.
It is well known that the angles of the front wheels and the tire pressure has a significant impact on their wear, vehicle handling and safety movement in General. Therefore, these diagnostic parameters should be checked on a regular basis. Stand model 9820 (Sims und Klein) is designed to control the geometry of the wheels. Large alphanumeric led indicators display information about the angles of the toe and camber, the longitudinal tilt of the king pin, centering steering. Stand samoustranitsya, manages the microprocessor. Unlike other similar devices that use special optics, in the stand of the applied liquid and semiconductor sensors for detecting angular and linear displacement.
Tire wear is affected and wheel balancing. French firm of Boehm Muller produces stand model 5609 for balancing wheels without removing them from the car. On the mobile trolley is fitted with a small electric motor, provided with a device for spinning the wheel, which pre-lift transmission Jack. The vibrations of the vehicle suspension caused by the imbalance of the rotating wheel, perceives piezoelectric transducer. When you receive the maximum signal is activated, a strobe lamp and the operator easily determines the position of the unbalanced mass. Coming from the sensor signals after conversion displays a dial indicator with a scale of prograde-of Rowan in grams additional weight.
Recently found wide application in technology endoscope - a medical device for examination of the stomach. The company "Starts" (Germany) produces a type of endoscope light - Motocop designed to autodiagnosis. Powerful focused light beam is directed through a flexible optical waveguide to the sample surface. The brightness of the lamp manages the trinistorny regulator. A special nozzle is allowed to observe with increasing hidden to the eye pockets of corrosion, the nature of the wear parts in closed cavities, the surface of the cylinders etc., the object may be photographed or displayed in an enlarged scale on the display screen.
Even from our brief review shows how durable is today with electronics in the diagnostics. With the aid of a microprocessor in the near future, the machine itself will set diagnosis." Constantly asking every few minutes on the programmed cycle controlled parts of the vehicle, the alarm system gives the driver the processed information prepared phrases, for example: "reserve fuel", "oil pressure drop", "speeding", etc., in Parallel, the display shows the values of the measured parameters. Changes and sensors that convert various electric signals into electrical signals. Information from the sensors will be supplied in one line, ring covering the car.
Author: A. Crimea, Moscow; Publication: N. Bolshakov, rf.atnn.ru