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英文原文1. The carburetorCarburetor is under the effects of the vacuum engine working, will be a percentage of the fuel and air mixing mechanism. It to important function that the engine can be called the heart of the engine. The complete device shall include starting device, idle speed device, medium load, full load device, accelerating device. Carburetor will according to the requirements of different working state of the engine, automatically matching the corresponding concentration, output the corresponding amount of mixture, in order to make the mixture mixed more evenly, carburetor has make fuel atomization effect, for the normal operation of machine.Simple carburetor is made up of 3 three parts, the part with air inlet and the float chamber, the middle section there are pipes, orifice, nozzle, how a portion of the valve, etc. Float chamber is a rectangular container, store of gasoline from the gasoline pump, there is a float container using surface (oil level height controls the input. In the middle of an oil inlet and the amount of float chamber nozzle hole, the other end oil outlet in throat throat.It is throat waist, two big middle small, of which the minimum cross-sectional area of throat. Suction when the engine is started the piston downward, inhalation of maximum speed when the airflow through the throat, static pressure is the lowest, so the throat pressure less than atmospheric pressure, that is to say throat throat and produced the pressure difference between the float chamber, that is the people often say vacuum, the greater the pressure range of vacuum. Under the action of gas in the vacuum from the oil outlet nozzle jet, because of throat throat 25 times that of gas flow rate of air flow, so the nozzle jet flow that is dispersed by high speed air flow, forming fog particles of various sizes, namely atomization. Initial atomizing oil mixed with air into a mixture, through the throttle, air intake pipe and inlet valve into the combustion chamber of cylinder. Here, the throttle opening size and rotational speed of engine, determined the throats of vacuum degree, and the throttle opening change directly affects the mixture ratio of ingredients, these are the important reason for affecting the operation of the engine.Changes due to the concentration of the mixture with engine under various operating conditions of load change is closely related, simple carburetor far cannot satisfy the change request at any time, so people on the simple carburetor constantly add new device used for adjusting the working state of the carburetor. Development today, has formed the carburetor has a variety of auxiliary equipment, mainly are idle, tangy, acceleration and initiating device. Now 4 cylinder engine common dynamic carburetor carburetor is double cavity, it has two pipes, and according to the different engine operating conditions or work at the same time, respectively. 6 cylinder engine common carburetor is double cavity and carburetor, it is actually two single cavity carburetor and together, each cavity is responsible for half of the number of mixture gas cylinder. And multi-cavity carburetor, usually assembled on large power engine.Carburetor of the multiple functions of device, the main oil supply unit is in addition to the idle speed, engine working condition of various other needs of oil supply device, is the basic fuel supply carburetor structure. The idle device is in idle speed runtime provides few but strong mixture device, with the lowest stable engine speed. Add device is big engine load extra oil supply device, in order to make up for the inadequacy of the main oil supply. Accelerating device is increased when the car suddenly accelerated time of valve opening extra oil supply device, when the engine speed and power can be increased rapidly. Starter is to provide extremely rich mixture when the engine cold start device, the common way is in the front hose to a choke valve to control the volume.The speed of particular mention here. Working condition of engine idle speed is the most commonly used for engine thermal process and no parking stall and so on. For the car performance has very important significance, especially in city driving, idle speed condition often determine the cars fuel consumption and emission level.Engine idle speed running speed is typically 600 800 RPM, throttle close to shut down, the speed of pipes, vacuum degree cant float chamber gasoline it sucked out smoothly, but the throttle at the back of the vacuum degree is high. So just on the basis of simple carburetor of setting up a idle oil duct, the nozzle is located in the throttle, the problem is solved.Due to idle need less thick mixture, the engine operation condition is more sensitive, stable and should be the minimum speed of the idle state, to control the oil amount of the adjustment and the opening of throttle. Now the carburetor of idle speed device has two adjusting screw, adjust the oil and the throttle opening respectively. At the same time, in order to prevent the phenomenon of close auto ignition switch and the engine is still running, the oil in the carburetor idle way will also include a idle speed solenoid valve, specifically responsible for opening and closing the idle oil duct, guarantee engine can quickly shut down.2. The working principle of the carburetorCarburetor is actually a pipe, tube middle there is a called the throttle adjustable plate door plank, is used to control the flow of air through the tube. Tube has a section called venturi contraction, the shrinkage will form a vacuum. The contraction section orifice, the use of vacuum can be hole inhale fuel from now on.Motorcycle carburetor looks very complex, but as long as grasp some principle, can adjust the motorcycle to the best state. All carburetors are working under the basic principle of atmospheric pressure. Atmospheric pressure is a power to put pressure on everything. It will have slight variations, but usually fifteen pounds of pressure per square inch (PSI). This means that the atmospheric pressure in anything is fifteen pounds per square inch pressure. By changing atmospheric pressure within the engine and carburetor, you can change the pressure and make the fuel and air flow through the carburetor.The atmospheric pressure will spread from high pressure to low pressure. When two stroke engine piston at top dead center (or four stroke engines piston at the check point), under in the crankcase piston (four-stroke engine piston above) will form a low pressure. At the same time, the low pressure can also cause low pressure in the carburetor. Because of the high pressure compared to the outside of the engine and carburetor, will burst into the carburetor and air into the engine until the pressure is balanced. Air flowing through the carburetor will drive the fuel, and fuel will be mixed with air.Inside the carburetor is a throat. Throat is inside the carburetor forced air speed through the contraction section. Can all of a sudden narrowing river to illustrate the situation of occurred in the carburetor. Narrow the river near the Banks of the river will speed up, if Banks continuous narrow will be faster. If the same thing happen in the carburetor, accelerate the flow of air will lead to the inside of the carburetor air pressure is reduced.Gasoline is the fuel tank through the fuel filter again into the carburetor, fuel filter the impurities can be mixed with gasoline and the scale filter inside the tank. If the filter quality defective, there are still some impurities through the filter into the carburetor. Other gasoline contained can form gel ingredients after long time deposit will condense out of the colloid, attached to the carburetor parts (such as orifice), oil and float on the surface.Air is through air filter into the carburetor, based on the air intake resistance cannot be too big and other factors to consider, filtering device cannot too tight, so part of the tiny impurities in the air will enter the carburetor through air filter. If the filter quality defective, can cause more serious influence.Composition in the airways of the carburetor oil duct, more spare parts, such as the main measure holes, idle hole orifice, primary air, idle air hole, the foam pipe, and so on all have inside a small hole (diameter between 0.3 1.5 mm), into the carburetor petrol impurity, colloid and impurities in the air, tend to the aperture change or jams, cause carburetor airway, poor oil duct, make the carburetor fuel supply characteristics change, even cause the carburetor performance failure.3. The pneumatic systemPneumatic technology is one of the ways in which industrial production mechanization and automation. Pneumatic system the use of safe, reliable, can be in high temperature, vibration, corrosion, inflammable, explosive, more dust, strong magnetic, radiation, etc. Work under the bad environment, which application is increasingly wide. Pneumatic system and hydraulic system, are made by one or more of the most simple of basic circuits. Pneumatic circuit and common basic circuit is in order to achieve the specific functions and pneumatic components and pipes in a certain way of combined structure, analysis, design and use of the pneumatic system is.Pneumatic transmission and control is one of the most effective way in the production process automation and mechanization, but its working medium (compressed air) manufacturing cost is high, the energy utilization rate is quite low. Pneumatic actuators is mainly used to make linear reciprocating motion. Engineering practice, this kind of movement form used most, such as many machines or devices transmitting device, product processing workpiece feeding, positioning and clamping workpiece, workpiece assembly and material forming are linear motion form. But some pneumatic actuators can make rotation movement, such as the oscillating cylinder (swing Angle is 360 ). Pneumatic technology application range, in addition to the individual circumstances, to do linear motion form, from the technology from a cost point of view, all mechanical SheBi cannot compared with pneumatic equipment. (from the technical and cost point of view, cylinder as actuator is the best form of complete linear motion, like motor to complete rotation movement.) Pneumatic technology, the interaction between actuators and control element is based on the simple element. Mission requirements, these components can be assembled into a variety of system solutions. Pneumatic control agencies or equipment greatly improve the mechanization degree, and can realize fully automated, pneumatic technology has made a significant contribution to the cheap automation. In fact, a single pneumatic components, such as various types of cylinder and control valve) can be as modular components, this is pneumatic components must be combined, to form a control loop used to complete a specific assignments. Broadly speaking, pneumatic equipment can be applied to any engineering field. Pneumatic equipment is often by a small amount of pneumatic components and several basic loop combination. Pneumatic control system composition is reproducible, it laid the foundation for combination and pneumatic components and applications. In general, the combination of pneumatic components with many reservations within functions. Batch feeder is also often used as a component to provide the whole machine. Thus greatly simplify the pneumatic system design, reduce the workload of design and installation debugging personnel, make the pneumatic system cost is reduced greatly.Pneumatic system basic composition: composition of the pneumatic circuit to drive mechanism for various purposes, its content is: the three most important control force, the size of the force direction and speed of movement. Connected to production devices of various types of cylinder, by pressure control valves, directional control valves and flow control valve, the contents of the three control is implemented, i.e., the pressure control valve, pneumatic control the size of the output force, direction control valves, control the movement direction of the cylinder, the speed control valve - control the movement of the cylinder. A pneumatic systems typically include air equipment (air compressor, gas), gas source treatment components, after cooler, filter, dryer and drainage), a pressure control valve (pressure valve, pressure reducing valve, relief valve, sequence valve, etc.), lubrication components (oil mist, centralized lubrication components), direction control valves, solenoid directional control valve, pneumatic directional control valve, control reversing valve, mechanical control reversing valve, check valve, etc.), various types of sensors (magnetic switch, limit switches, pressure switches, pneumatic sensor), flow control valve (speed control valve, cushion valve, quick discharge valve), cylinder actuators (cylinder, gas motors, vacuum suction cup, etc), other auxiliary components (muffler, connection and trachea, hydraulic buffers, converter gas and liquid, etc.). A typical pneumatic system consists of direction control valves, pneumatic actuators, pneumatic auxiliary components and air purification device.4.The PLCPLC is a specialized in industrial environment application and design of the electronic device digital computing operations. It can adopt program memory, used in its internal storage implementation logic operation, sequence operation, timing, counting and arithmetic operation instruction, and can through digital or analog input and output, control various types of machinery or production process. PLC and related peripheral equipment should be in accordance with the easily and industrial control system to form a whole, easy to expand its function design principles. Early Programmable Controller called Programmable Logic Controller (Programmable Logic Controller, PLC), it mainly used instead of relay realize Logic control. With the development of technology, which USES a microcomputer technology of industrial control device functionality is considerably more than the scope of logic control, therefore, today the device called the programmable controller, hereinafter referred to as PC. But in order to avoid and Personal Computer (Personal Computer) abbreviation confusion, it will be referred to as PLC programmable controller. PLC data since 1969, when the American equipment corporation (DEC) is developed, the United States, Japan, Germany, the programmable controller of high quality, powerful function. PLC is a specialized in industrial control computer, its hardware structure is basically the same with a microcomputer, basic structure as follows:a. The powerPLC power plays a very important role in the whole system. If you dont have a good and reliable power supply system is unable to work normally, so PLC manufacturer of power supply design and manufacturing also attaches great importance to. General ac voltage fluctuation within + 10% (+ 15%), can not take other measures to PLC directly connected to the ac gridb. A central processing unit (CPU)The central processing unit (CPU) is the control center of the PLC. Which is in accordance with the function of the PLC system program to receive and storage from the programming device type in the user program and data; Check that the power supply, memory, I/O and warn the timer state, and diagnose the grammatical errors in the user program. When PLC in operation, the first it receives in the form of scanning field state of each input device and data, and deposited in the I/O image area respectively, and then from the user program memory to read a detailed user program, after command interpretation shall be governed by the provisions of the directive arithmetic or logical operations into the I/O image area or the result of the data register. Etc. After all of the user program has been completed, and finally to the I/O image in the output state or output register data transmitted to the appropriate output device, so cycle run, until stop running.In order to further improve the reliability of PLC, to large PLC also adopts double CPU redundancy system, CPU or the use of three voting system. In this way, even if a CPU fails, the whole system can still run normally.c.The memoryMemory to store system software is called the system program memory, memory storage applications called user program memory.d.The input and output interface circuit1. The input interface circuit and microcomputer by optical coupling circuit of the input interface circuit, PLC is used with the control interface interface input channel.2. The output interface circuit by the output data registers, called the road and interrupt request circuit integration, the function of PLC through the output interface circuit output corresponding control signal to perform on site components.e. The function moduleSuch as counting, positioning function module.f.The communication moduleSuch as Ethernet and RS485, profibus-dp communication module, etc.5. The characteristics of the PLC(1) the function is perfect, flexible combination, extension, convenient and practical. The functions of modern PLC and its various extension units, intelligent units and special function modules, can be convenient, flexible, varying in size and require the control system, in order to adapt to the needs of all kinds of industrial control. To switch quantity control for the specialty; Can continuous process PID loop control; And with the upper body into a complex control system, such as DDC and DCS, realize the comprehensive automation of production process.(2) easy to use, simple programming, using simple ladder diagram, logic diagram or statements table such as programming language, without the need for computer knowledge, so the system development cycle is short, the scene debugging easier. The use of PLC can modify the program online, change control schemes without having to tear open machine equipment. It can run in a different environment, the reliability is very strong.(3) simple installation, easy maintenance. PLC can be run directly under all kinds of industrial environment, you only need to the scene of the various devices connected to the PLC corresponding I/O at, write programs to run. On various modules are run and fault indication device, making it easy for users to understand operation and malfunction. PLC has strong self-checking function, which provides the convenience for its maintenance.(4) the ability of anti-jamming and reliability are strong, far higher than other models. Isolation and filtering, are two main measures of anti-interference. Of the PLCs internal power also took measures such as shielding, voltage stability, protection, in order to reduce interference, ensure the quality of power supply. In addition to input/output interface circuit of the power independent of each other, in order to avoid interference between the power supply. Right choice grounding place and perfect system is the PLC control system is one of the important measures of resistance to electromagnetic interference. In order to adapt to the severe environment of working site, also USES the sealing, dustproof, seismic shell encapsulation structure. Through the above measures to ensure that the PLC can reliable operation in harsh environment, the average time between failures, fault repair time is short.(5) low environmental requirements. PLC technology can conditions in high temperature, vibration, shock, dust and other harsh environments, able to work under the environment of strong electromagnetic interference and reliable. This is market survival value of PLC products.(6) easy to learn and easy to use. PLC is an industrial and mining enterprises of the industrial control equipment, easy interface, programming language is easy to accept for engineering and technical personnel. Similar- 配套讲稿:
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