Design and operation of the K-22G carburetor

Carburetor K-22G vertical, with falling mixture flow, balanced

It consists of a float chamber, a main jet device, an additional (compensation) jet device, a starting device and an idle jet, an accelerator pump, a power jet (economizer), a mixing chamber and an engine speed limiter.

Each jet consists of a plug with a calibrated hole (the jet itself), a spray tube and channels supplying gasoline from the float chamber to the jet and from the jet to the spray.

The nozzles of all jets are routed into the carburetor diffuser block.

The carburetor consists of three main parts (Fig. 1): cover 13, body 4 and pipe.

A block of 10 diffusers is attached between the cover and the carburetor body.

For tightness, a sealing gasket 5 is placed between the cover and the carburetor body. A sealing gasket is also placed between the carburetor body and the pipe.

In the lower part of the pipe there is a flange, which, with an iron-asbestos gasket on two studs, secures the carburetor to the inlet pipe.

Depending on the operating mode of the engine, gasoline is supplied through various carburetor jets to prepare the combustible mixture.

When starting a warm engine or when operating at low idle speed, gasoline enters the mixing chamber through the idle jet.

At low and medium speeds at low and medium loads, when the throttle valve is open more than at idle speed, but less than at full engine load, gasoline enters the mixing chamber only through the main jet.

As the engine speed increases, gasoline begins to flow through the additional jet.

And the higher the engine speed, the more gasoline passes through the additional jet.

The carburetor is designed and adjusted so that the engine always operates in these modes with a lean (economical) mixture.

When the engine is producing maximum power, the throttle valve is fully open.

In this case, not only the main and additional jets work, but also the power jet, through which the additional amount of gasoline necessary to obtain a rich mixture passes.

The power jet turns on every time the throttle valve is fully or almost fully opened at any engine speed, and not just at the maximum speed.

The carburetor float chamber is located in front of the mixing chamber.

A constant fuel level in the float chamber is maintained using a float and a needle valve.

Gasoline from the gasoline pump enters the float chamber through a needle valve, which is closed by the float after the chamber is filled to normal level.

The fuel level in the float chamber is at a distance of 17-19 mm from the upper plane of the body.

The carburetor float chamber is balanced, i.e. the air space of the chamber communicates not with the outside atmospheric air, but with the carburetor cover pipe through tube 13 (Fig. 2).

The air pressure in the balanced float chamber is the same as in the carburetor body cover pipe after the air filter.

The advantage of a balanced float chamber over an unbalanced one (connected to atmospheric air) is that the combustible mixture prepared by the carburetor is not enriched when the air filter is clogged.

When the engine is running, the air pressure in the housing cover pipe and, consequently, in the float chamber is always less than atmospheric pressure.

This turns out to be due to the resistance of the air filter and due to the higher speed of air passing through the pipe.

However, the air pressure in the diffusers is less than in the lid nozzle, since the air speed in the diffusers, which have a smaller flow area than the nozzle, is always greater than the air speed in the nozzle.

Consequently, when the engine is running, the air pressure in the diffusers is always lower than in the float chamber.

To eliminate the possibility of outside air penetrating into the float chamber, causing an imbalance in its balancing, starting from 1955, the carburetor cover is attached to the body with seven bolts instead of five.

Main and auxiliary jets

In the lower part of the carburetor body (Fig. 3) there is a socket through which the block of 2 atomizers of the main and additional jets exits into the diffuser block.

The nozzle block is secured in the socket with a block of 5 jets with sealing fiber gaskets.

Gasket 3 eliminates the possibility of gasoline penetrating into the mixing chamber in addition to the nozzles, and gasket 4 ensures tightness in the connection of the channels of the main 14 additional jets with their nozzles.

In the same socket with a sealing gasket 10, the housing 7 of the adjusting needle is screwed, which is also the plug of the socket,

In the needle body, an adjusting needle 8 is installed on the thread, which, when rotated, enters at different depths into the calibrated hole of the main jet located in the center of block 5, changing the cross-section of the jet. The needle is sealed with an oil seal located inside nut 9.

Between the needle body and the jet block there is a space that communicates with the float chamber through channel 6; the additional jet is not located in the center of the jet block.

It communicates with its atomizer by an annular recess at the end of the nozzle block and at the end of the nozzle block.

When the engine is not running, the gasoline in the main and auxiliary jet nozzles is at the same level as in the float chamber.

The atomizer block 2 is installed so that the main jet nozzle is located in the smallest section of the small diffuser 13, and the additional nozzle nozzle is in the neck 15 of the diffuser block.

In Fig. Figure 3 shows the operation of the carburetor at low speeds and low engine load, when the air damper 1 is fully open and the throttle valve 11 is open more than at idle speed, but less than at maximum power.

In this case, all the air passes through the neck 15 of the diffuser block and then through two diffusers simultaneously: small 13 and medium 12, as well as through the slots formed between the ends of the spring plates 14 of the diffuser block and the end of the middle diffuser (see section A -A).

The air speed in the neck of the diffuser block is not sufficient to create the pressure drop necessary for the operation of the additional jet, and in the small diffuser the air speed is sufficient to create the necessary difference in air pressure at the holes of the main jet nozzle and in the float chamber, causing gasoline to flow out of the diffuser spray nozzle.

To operate the main jet, the pressure difference may be less than that required to operate an auxiliary jet whose nozzle end is higher than the nozzle end of the main jet.

In a small diffuser, gasoline is atomized with air for the first time. When leaving the small diffuser - a second time (with the same air that enters the middle diffuser).

When leaving the middle diffuser, gasoline is atomized again (by air that passes through the gaps between the ends of the spring plates and the end of the middle diffuser).

As the engine shaft speed increases, the air speed in the neck of the diffuser block and in the small diffuser increases.

This leads to an increase in the flow of gasoline from the main jet nozzle and the mixture leaving the middle diffuser becomes richer. But since, as the air speed increases, the spring plates of the diffuser block automatically move apart, allowing air to pass through, the composition of the mixture remains the same.

With a further increase in the throttle opening, the air speed in the neck of the diffuser block increases, causing gasoline to begin flowing through the additional nozzle.

However, in this case, the composition of the combustible mixture remains the same as when operating one main jet, since the throughput of the additional jet and the elasticity of the plates of the diffuser block are selected accordingly.

Accelerator pump

When the throttle valve is opened sharply, the fuel mixture becomes leaner.

This happens because the flow rate of gasoline increases much more slowly, 600 times less than the specific gravity of gasoline.

To ensure good acceleration of the car, it is necessary that when the throttle valve is opened sharply, the fuel mixture does not become leaner, but becomes richer.

When the throttle valve is opened sharply, the mixture is enriched using the accelerator pump.

The accelerator pump consists of a well in which the piston moves and a valve system.

The piston is moved by rod 8, which, through rod 30 (Fig. 1) and lever 31, is driven by throttle lever 40.

In Fig. Figure 4 shows the operation of the accelerator pump. From the float chamber, gasoline enters the pump well through inlet valve 6, filling the well to the level of gasoline in the float chamber.

As piston 7 moves from top to bottom, gasoline pressure is created in the well, under the influence of which the inlet valve 6 closes and the discharge valve 9 opens. Gasoline passes through the discharge valve through channel 2 and is injected through the sprayer 1 into the diffuser block.

When the throttle valve is sharply opened, the piston rod 4 moves along the piston driver 3 and compresses the piston drive spring 5. By expanding, the spring moves the piston and ensures smooth and uniform fuel injection.

Thanks to this, fuel injection continues significantly longer than the throttle opening period.

When the throttle valve is slowly opened, and, consequently, when the accelerator pump piston moves slowly, fuel injection does not occur, since the gasoline displaced by the piston exits back into the float chamber through the inlet valve 6, which does not close due to the lack of gasoline pressure.

For the same reason, injection valve 9 does not open, preventing gasoline from penetrating into the diffuser block and enriching the mixture unnecessarily.

But already at an increased speed of opening the throttle valve, the gasoline pressure becomes sufficient to close the inlet valve, open the discharge valve and inject gasoline.

Gasoline, which has penetrated into the gaps and ends up on top of the piston, flows into the float chamber through slot 8 during the upward stroke of the piston.

The K-22G carburetor does not provide the ability to change the amount of gasoline injected by the pump depending on the time of year, since the performance of the accelerator pump, equal to 1.0 cm³ per working stroke, ensures proper enrichment of the mixture and for the winter season.

Power jet

It was already mentioned above that the engine develops the most power with a rich mixture.

When the vehicle is running, maximum engine power is used quite rarely.

To reduce vehicle fuel consumption, the carburetor adjustment is selected so that at medium loads the engine runs only on the economy mixture.

The carburetor has a power jet, which is Pressures the mixture when it is necessary to obtain the greatest engine power.

Figure 5 shows the power jet design.

The K-22G carburetor has a mechanical drive for turning on the power jet, which is combined with the accelerator pump drive.

The power jet consists of a ball valve 4, located at the bottom of the accelerator pump well, and channel 5, through which fuel from the valve is supplied to the additional jet nozzle.

The accelerator pump piston drive rod is pivotally connected to the throttle valve so that when the throttle valve is closed, the piston is in the upper position, and when open, it is in the lower position.

As long as the throttle valve is not fully open, the power jet cannot be turned on.

To obtain the greatest power, the throttle valve opens completely, the piston is lowered to the lower position and needle 3 presses the nozzle valve ball and enriches the mixture.

Starting device and idle jet

When starting a cold engine, the speed of air passing through the carburetor is low and the mixture is not heated.

This does not allow all the gasoline to evaporate, and mainly the starting fractions participate in the formation of the combustible mixture.

In order for the resulting combustible mixture to be able to start the engine under the specified conditions, several times more gasoline is required than under normal operating conditions; the mixture must be over-enriched.

Re-enrichment of the mixture is achieved by increasing the vacuum in the mixing chamber, as a result of which gasoline enters the mixing chamber not only from the idle jet, but also from the main and additional jets.

To re-enrich the mixture, the carburetor has a special device, shown in Fig. 6.

The device consists of an air damper 12 located in the upper part of the inlet pipe of the carburetor cover, two levers 7 and 10 and a flexible rod 6 for the damper drive.

In the pipe, the damper is mounted on an axis not in the center, but so that its lower part is significantly larger than the upper.

Two holes are stamped in the lower part of the damper, closed by valve 14 under the action of spring 13. A lever 10 is mounted on the damper axis, which, by the force of the spring 11, constantly holds the damper in the closed position.

The air damper is controlled from the dashboard using a flexible rod, the handle of which is located on the instrument panel.

The thrust drives the fork-shaped drive lever 7, which, acting on the air damper lever 10, opens or closes the damper through the bent arm 8.

Spring 9 presses lever 7 to the position corresponding to the fully open air damper, and when the flexible rod is suddenly disconnected, it holds the damper in the open position.

In Fig. Figure 6 shows the damper drive positions corresponding to:

• a) a forced closed damper; in this position of lever 7, the control handle for the flexible rod of the air damper drive is extended to its full stroke;
• b) and c) the position of lever 7, which allows lever 10 (under the action of spring 11) to automatically close the damper or (Fig. 6, c) to automatically open the damper as much as it can open it, overcoming the action of spring 11, flow of air entering the pipe; in this position of lever 7, the flexible rod control handle is extended approximately ⅔ of its stroke;
• d) forced fully open damper; in this position of lever 7, the valve cannot close, since lever 10 rests against lever 7 with shoulder 8; in this case, the control handle of the flexible rod of the damper drive is pushed into the guide sleeve completely to the extent of its stroke.

The operation of the carburetor when starting a cold engine is shown in Fig. 7. Air flows through valve 3 of the closed air damper 2. Narrow gaps remain between the throttle valve 5 and the pipe when starting the engine.

Below the upper edge of the damper, in the area of the upper slot, in the pipe there are two spray holes 6 and 8, through which the emulsion prepared by the idle jet passes.

Both holes communicate with channel 9 in the carburetor body.

This channel connects holes 6 and 8 with the air jet 14 and the emulsion jet 12.

Channel 4 is connected to the petrol jet socket 10, through which petrol is supplied from the additional jet.

The gasoline jet is connected by channel 11 to the emulsion jet 12 and the air jet 13.

When the engine is not running, gasoline in channel 11 is at the same level as in the float chamber.

Under the influence of vacuum in the area of the spray holes that occurs when starting the engine, gasoline from the float chamber through gasoline nozzle 10 enters channel 11.

Air from the carburetor cover pipe passes into the same channel through air jet 13 through channel 1 and is mixed with gasoline for the first time.

The resulting emulsion exits through nozzle 12 into channel 9, is mixed a second time with air, which is supplied to channel 9 through air nozzle 14 and flows through channel 9 to the spray holes.

The main spraying of gasoline occurs when the emulsion exits spray holes 6 and 8 of the idle jet.

When the engine starts, the emulsion comes out of both holes.

Atomization of gasoline coming out of the nozzles of the main and additional jets occurs when the mixture passes through the gap between the throttle valve and the pipe.

Therefore, when starting a cold engine, the mixture damper does not need to be opened more than it is opened automatically by arm 3 of lever 4 (Fig. 8) when closing the air damper.

If the throttle valve is opened more, poorly atomized gasoline will spray into the spark plugs, making it impossible to start the engine.

To start a warm engine, as well as to keep the engine idling, a less rich mixture is required (about 9 parts by weight of air to one part of gasoline).

As a result, there is no need to close the air damper.

In this case, gasoline flows only through the idle jet.

The composition of the mixture prepared by the idle speed device depends on the throughput of the gasoline and air jets.

The adjusting screw 7 (see Fig. 6), installed opposite the lower spray hole 6, regulates only the amount of emulsion coming from the lower spray hole at low idle speed.

The operation of the idle jet when starting a warm engine and at minimum engine idle speed is shown in Fig. 9.

The top edge of the flap is above the top hole.

The emulsion comes out of both holes.

The emulsion passes through the upper hole at increased idle speeds, and it serves for a smooth transition from engine operation at idle speed to operation at medium loads.

Revolution limiter

The speed limiter prevents the engine crankshaft from reaching more speed than is necessary for normal truck operation.

It operates automatically depending on the flow rate of the mixture in the carburetor.

The limiter, of which the carburetor throttle valve is part, reduces the filling of the cylinders with the mixture when the engine speed becomes higher than necessary to move a loaded vehicle at a speed of 70 km/h (in fourth gear, on a flat section of the road), and also does not allow the engine crankshaft to develop without load above 4300 rpm, which significantly extends its service life.

The limiter does not impair engine response, since it does not prevent the engine from running at full throttle until the engine crankshaft reaches its maximum permissible speed.

The limiter is especially important in that it prevents the engine from “running away” when operating without load.

The speed limiter is shown in Fig. 10.

The limiter consists of a throttle valve 7, a spring 1, a limiter spring tension bushing 2 and a limiter clutch 3.

The carburetor throttle valve has a special shape and is located on an axis offset from the axis of the pipe.

The throttle valve drive has a special device.

In Fig. Figure 1 clearly shows the device of the limiter and the damper drive.

Valve 1 is freely mounted on axis 38 on needle bearing 2.

One end of the spring 35 with a pin, which passes between the coils of the spring, is attached to the limiter coupling 34, and the other end is attached to the roller of the damper earring.

When the clutch 34 rotates, the number of working turns of the spring 35 changes.

The spring tension is regulated by a sleeve 36 moving along the threads in the carburetor pipe.

To rotate the throttle valve, there are cams on its axis, into the groove between which the valve fits.

The thickness of the damper is less than the width of the groove between the cams, so there is free play in the damper drive.

The amount of free play is greater than the travel of the damper until it is fully opened.

The position corresponding to the fully open damper is fixed by a pin pressed into the damper, which, when the damper is fully open, rests against the carburetor pipe.

The limiter spring constantly strives to open the throttle valve, but the valve rests against the cams of axis 38 (Fig. 1) and does not open until the driver, by pressing the throttle pedal, turns the valve axis and thereby moves the cams away.

When the pedal is released, the damper drive tension spring rotates the damper axis, the cams of the axis press the damper, which closes, stretching the limiter spring.

As the engine speed increases, the pressure of the mixture flow on the inclined surface of the throttle valve increases.

At the moment when the pressure of the mixture flow on the damper is stronger than the action of the spring, the damper begins to close regardless of the position of the pedal (which allows it to move freely in the groove between the cams), and the engine crankshaft speed decreases.

There is a special protrusion on the throttle linkage. It serves to increase the leverage of the spring force after the damper closes enough to rest against this protrusion.

When the damper is closed further, the action of the limiter spring increases significantly and prevents the possibility of complete closing of the throttle valve under the influence of vacuum and mixture flow.

The moment the limiter comes into effect depends on the tension of its spring.

The more the spring is tensioned, the higher the maximum engine speed of the crankshaft, since a greater pressure of the mixture flow is required to begin closing the damper.

By changing the spring tension, you can adjust the maximum engine crankshaft speed.

The spring tension is controlled by two damper positions. One position corresponds to 3500 - 4300 rpm of the engine crankshaft when operating without load.

In the K-22G carburetor in this position the damper is at an angle of 21 ÷ 23° relative to the position occupied by the fully open damper.

The damper is open relatively little, so the limiter spring is stretched almost completely, the other position corresponds to 2800-3175 rpm of the engine crankshaft with full load; in the K-22G carburetor it corresponds to an angle of 3 - 4°, i.e. the damper is almost completely open.

The limiter spring is almost not stretched.

The spring tension mechanism is closed by a cap, inside of which there are planes for locking the hexagons of the coupling and the spring tension nut, which eliminates the possibility of arbitrary adjustment changes.

The spring tension is adjusted at the factory using a special device, after which the screws securing the cap are sealed so that this adjustment cannot be adjusted during operation to be violated.