Since gasoline engines are easier to start at different temperatures, special diesel engines are used to start the engine on some of the more powerful diesel engines. This type of gasoline engine is usually called a start-up gasoline engine. It is an important part of the use of a gasoline engine in winter if the correct operation of gasoline engine carburetor valves can be achieved during work. It directly affects the starting performance, economic performance, and dynamic performance of the engine. The operating method is described as follows:
First, start
When the starter starts, the rotation speed of the starter is very low, the air flow is slow, and the degree of vacuum at the throat is not large, so that the amount of oil discharged from the main nozzle is not large, and the engine temperature is low, which is not conducive to vaporization, and most of the gasoline emitted is emitted. Condensed on the wall of the intake pipe, only a small part of the air mixed. Therefore, to increase the actual concentration of the mixture, it is necessary to increase the supply of gasoline. For this reason, different engine carburetors are provided with different concentration devices. Taking the 223 carburetor as an example, a small damper is closed at startup, on the one hand, the air entering the carburetor is reduced, and on the other hand, the vacuum behind the choke is increased so that gasoline can be ejected from all the spouts (main spout, rapid spout, transition spout ). In addition, before the start, the concentration button should be adjusted to improve the floater's oil level, so that the oil can overflow from the main nozzle and increase the concentration of the mixture to meet the requirements of the start-up. Immediately after startup, the choke valve should be opened, otherwise the air-fuel mixture will be more and more concentrated as the engine speed increases, causing the engine to smoke or even turn off.
Second, rapid operation
When the engine runs at a high speed, on the one hand, due to the low speed and temperature, it is not conducive to the ejection and vaporization of gasoline. On the other hand, since only the friction resistance of the engine itself is overcome at this time, the amount of air-fuel mixture required is small, so that the cylinder The proportion of the remaining exhaust gas in the mixture is relatively high. To avoid over-leaning of the mixture during rapid operation, ensure that there is enough vaporization of gasoline to stabilize the engine at low-speed idling, and then the carburetor supplies a small amount of high when it is required to run at a high speed. Concentration mixture.
In order to meet the requirements of the rapid operating conditions for the mixture gas concentration, in the rapid operation, it is required that the choke valve is fully opened and the throttle valve is slightly opened (commonly referred to as the throttle). The air velocity at the throat is small and the vacuum is not so great that gasoline cannot be ejected from the main jet. At this time, the degree of vacuum behind the throttle valve is very large, and the rapid nozzle emits a foam-like emulsion formed after premixing with the air entering the transition nozzle, and is blown and atomized by the airflow flowing along the edge of the throttle. Since the throttle is opened slightly at this time, the amount of air in the mixture is very small, so that a rich combustible mixture is formed to meet the requirements of rapid operation.
Third, load work
When the load is working, the throttle valve should be opened large, so that the air velocity at the throat pipe increases, which is beneficial to the atomization and atomization of gasoline. At the same time, since the engine temperature increases, the gasoline is easy to evaporate and vaporize, so the mixture gas forming conditions are improved. To ensure that the mixed gas can be completely burned during the load operation, to achieve economical purposes, it is necessary to increase the proportion of air in the mixture so that the carburetor can supply a low concentration of the mixture.
In summary, whether it is a special start gasoline engine or a gasoline engine for motorcycles or automobiles, under different ambient temperatures, different operating conditions require different operating requirements for choke and throttle valves. Really understand the different operating conditions on the mixture of gas concentration, the number of requirements in order to properly operate in use.
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