The carburetor is what? Principle of operation, application

In this article you will learn about fuel injection systems. The carburettor is the very first mechanism that allowed to combine gasoline with air in the right proportion for the preparation of a fuel-air mixture and its supply to the combustion chambers of the engine. These devices are actively used to this day - on motorcycles, chainsaws, motorcycles and so on. That's only from the automotive industry, they have long been supplanted by injection injection systems, more advanced and perfect.

What is a carburettor?

The carburettor is a device that mixes fuel and air, supplies the resulting mixture to the intake manifold of an internal combustion engine. Early carburettors worked, simply allowing air to pass on the surface of the fuel (in the specific case - gasoline). But most of them later distributed the measured amount of fuel into the air stream. This air passes through the jets. For a carburetor, the condition of these parts is extremely important.

The carburetor was the main instrument for mixing fuel and air in internal combustion engines until the 1980s, when doubts arose about the effectiveness of its use. When fuel burns, a lot of harmful emissions are formed. Although carburettors were used in the United States, Europe and other developed countries until the mid-1990s, they worked alongside more sophisticated control systems to meet the requirements for carbon dioxide emissions.

History of development

Various types of carburetors were developed by a number of pioneers in the automotive industry, including the German engineer Carl Benz, the Austrian inventor Siegfried Markus, the English scholar Frederick W. Lanchester, and others. Since so many different methods of mixing air and fuel were applied in the early years of the existence and development of cars (and originally stationary petrol engines also used carburetors), it is difficult to determine exactly who is the inventor of this complex device.

Types of carburettors

Early designs differed according to the basic method of operation. They also differ from the more modern ones that dominated throughout much of the twentieth century. Modern carburetor for chainsaw spray type, the same are used on modern cars. The very first, historical, so to speak, designs can be divided into two main types:

1. Surface type carburetors.
2. Spray carburetors.

Let us examine them in detail later.

Surface carburettors

All early designs of carburetors were superficial, although there was a wide variety in this category. For example, Siegfried Marcus introduced something called the "rotating carburetor brush" in 1888. And Frederick Lanchester developed his carburettor wick in 1897.

The first carburetor float was developed in 1885 by Wilhelm Maybach and Gottlieb Daimler. Karl Benz also patented a carburetor of the float type at about the same time. Nevertheless, these early designs were surface carburetors that worked by passing air above the surface of the fuel in order to mix them. But why do you need a carburetor engine? And without it, it was not possible to feed the fuel mixture to the combustion chambers (the injector was not yet known in the nineteenth century).

Most surface devices functioned on the basis of simple evaporation. But there were other carburetors, they were known as devices that work by "bubbling" (they are also called filter carburetors). They work by forcing the air to move up through the bottom of the fuel chamber. As a result, a mixture of air and fuel is formed over the main volume of gasoline. And this mixture is subsequently sucked into the intake manifold.

Spray carburettors

Although various surface carburetors were dominant during the first decades of the car's existence, spray carburetors began to occupy a significant niche at the turn of the 19th and 20th centuries. Instead of relying on evaporation, these carburetors actually sprayed a measured amount of fuel into the air that was sucked in by the air intake. These carburetors use a float (like Maybach and earlier Benz designs). But they acted on the basis of the Bernoulli principle, as well as the Venturi effect, as well as modern devices, such as the K-68 carburetor.

One of the subtypes of aerosol carburettors is the so-called carburetor of pressure. It first appeared in the 1940s. Although the carburettors of pressure resemble aerosols only externally, they were in fact the earliest examples of devices for forced fuel injection (injectors). Instead of relying on the Venturi effect to suck fuel from the chamber, the pressure carburettors sprayed fuel from the valves in much the same way as modern injectors. Carburettors became increasingly complex during the 1980s and 1990s.

What does "carburettor" mean?

"Carburettor" is an English word that is derived from the term carbure, translated from French - "carbide." In French, a carburer simply means "combining (something) with carbon". Similarly, the English word "carburetor" technically means "an increase in the carbon content."

The K-68 carburetor works similarly, which was used on scooters of the Tula type (later the Ant), motorcycles Ural and Dnepr.

Components

All types of carburettors have different components. But modern devices have a number of common characteristics, including:

1. Air channel (Venturi tube).
2. Throttle valve.
3. The solenoid valve is idling.
4. Accelerating pump.
5. Carburetor chambers (primary, float and so on).
6. The float mechanism.
7. Carburettor membrane for fuel transfer.
8. Adjusting screws.

How does the carburetor work?

All types of carburetors work by means of various mechanisms. For example, carburetors of wick type work, causing air to pass through the surface of gas-impregnated wicks. This causes the evaporation of gasoline into the air. Nevertheless, devices of the wick type (and other superficial ones) have become obsolete over a hundred years ago.

Most carburettors, which are used by vehicles today, use a spraying mechanism. They all work in a similar way. Modern carburetors function due to the Venturi effect to draw fuel from the chamber.

Basic principles of carburettors

Carburettors, whose work is based on the Bernoulli principle, have some peculiarities. Air pressure changes are predictable and directly dependent on how quickly it moves. This is important because the air passage through the carburetor contains a narrow, compressed Venturi tube. It is necessary to accelerate the air as it passes through it.

The flow of air (not the flow of the mixture) through the carburetor is controlled by the accelerator pedal. It is connected to the throttle valve located in the carburetor, using a cable. This valve closes the venturi when the accelerator pedal is not used, and it opens when this pedal is depressed. This allows air to pass through the venturi. Consequently, more fuel is drawn from the mixing chamber. On such principles the carburetor's work is based.

Most carburettors have an additional valve above the venturi (called the throttle, which acts as a secondary throttle). The throttle remains partially closed when the engine is cold, which reduces the amount of air that can pass into the carburettor. This leads to a richer air / fuel mixture , so the throttle should open (automatically or manually) as soon as the engine warms up and will no longer need a rich mixture.

Other components of carburettor systems are also designed to affect the air-fuel mixture during various operating conditions. For example, a power valve or metering rod can increase the amount of fuel under an open throttle, or it occurs in response to a low pressure in the vacuum system (or the actual throttle position). The carburettor is not an easy element, and the physical foundations of its functioning are quite complex.

Problems

Some problems of carburettors can be solved by adjusting the air damper, the mixture or idle, and others require repair or replacement. Often wear out the carburettor membrane, stops pumping gasoline into the chambers.

When the carburetor breaks down, the engine will run poorly under certain conditions. Some problems of carburetor systems lead to engine failure, it can not operate normally at idle without assistance (for example, pulling a suction or constant sub-gas). The most common problems are manifested in the cold season, when the engine is most difficult to operate. A carburettor that works poorly on a cold engine can function normally when the heat is (this is due to problems with the coking of the channels).

It is worth noting that the carburetor for the motoblock has the same composition as the car. The difference in the number of elements and their size. In some cases, problems with the carburetor can be solved by manually adjusting the mixture or idle speed. For this purpose, the mixture is usually regulated by turning one or more screws. Needle valves are fixed on them. These screws allow physically to change the position of the needle valves, and this leads to the fact that the amount of fuel can be reduced (poor mixture) or increased (enrichment occurs), depending on the specific situation.

Carburetor Repair

Many problems of carburetor systems can be solved by making changes or performing other corrections without removing the device from the engine. To adjust the carburetor for the motor block, there is no need to remove it. But some problems can be solved only with the removal of the device and its full or partial restoration. The carburetor repair operation generally involves removing the block, disassembling it and cleaning it with a solvent designed specifically for this purpose.

A number of internal components, seals and other parts must then be replaced before installation. Only after careful handling, it is necessary to assemble the carburetor and replace it. To carry out high-quality maintenance, you will need a repair kit for the carburetor. It includes all the most important elements of the design.

So, we found out that the carburetor is literally a device that adds gasoline (fuel) to the air and feeds this mixture into the combustion chambers of the engine.