Starting device
The enrichment of the combustible mixture when starting a cold engine is ensured by closing the air damper 1 (see diagram) with offset axle. The air damper has a mechanical drive, which consists of a handle, rod, shell and lever. Simultaneously with the closing of the air damper, under the action of vacuum, the throttle valve 2 of the 1st chamber opens slightly. This leads to an increase in the engine speed to accelerate the warm-up of the engine.
When the engine switches to operating modes, the system of 3 rods and the lever opens the air damper, thus eliminating the re-enrichment of the combustible mixture when the throttle valve of the 1st chamber is opened.
Idle system and transition system
Diagram of the idle system and the transition system of the Keihin carburetor: 1 - air damper; 2 - throttle valve of the 1st chamber; 4 - main fuel jet of the 1st chamber; 5 - idle fuel jet; 6 - air idle jet; 7 - electromagnetic shut-off valve; 8 - adjusting screw quality (composition) mixtures.
From the float chamber, fuel is supplied through the main fuel jet 4 of the 1st chamber through the channel to the idle fuel jet 5. Not leaving the jet 5, the fuel mixes with the air leaving the vertical channel after the idle air jet 6. The emulsion passes through the channel, the flow section of which is blocked by the electromagnetic shut-off valve 7 at forced idle, and exits under the throttle valve through the hole regulated by the quality screw 8 (composition) dare.
When the throttle valve is opened before the main metering system of the 1st chamber is turned on, the air-fuel mixture enters the 1st chamber through the bypass channels of the transition system, the slots of which are located above the throttle valve in the closed position and are made at the level of the hole regulated by the quality screw (composition)
Main dosing system of the 1st chamber
Scheme of the main dosing system of the 1st chamber of the Keihin carburetor: 2 - throttle valve; 4 - main fuel jet; 9 - main air jet; 10 - emulsion tube; 11 power mode economizer valve; 12 - economizer valve piston; 13 - vacuum supply channel.
From the float chamber, fuel enters through the main fuel jet 4 (see diagram) into the emulsion tube 10, in the upper part of which it mixes with the air leaving the opening of the main air jet 9. The air-fuel emulsion is sucked into the small and large diffusers through the horizontal channel. In the full load mode of the engine, the vacuum in the intake manifold opens the valve 11 of the power modes economizer. The fuel leaving the economizer valve opening 11 is added to the fuel that passes through the main fuel jet 4, enriching the combustible mixture.
Main dosing system 2nd chamber
Scheme of the main dosing system of the 2nd chamber of the Keihin carburetor: 2 - throttle valve of the 1st chamber; 4 - main fuel jet of the 1st chamber; 14 - main fuel jet of the 2nd chamber; 15 - emulsion tube; 16 - main air jet of the 2nd chamber; 17 - slots of the transition system of the 2nd chamber; 18 - thermopneumatic valve; 15 - pneumatic actuator of the throttle valve of the 2nd chamber; 20 - axis of the throttle valve of the 2nd chamber; 21 - throttle valve of the 2nd chamber.
When the throttle valve of the 1st chamber is opened by a certain amount, the 2nd chamber is unlocked and the pneumatic actuator 19 acts on the throttle valve 21 of the 2nd chamber. The main dosing system of the 2nd chamber works in the same way as the main dosing system of the 1st chamber. The pneumatic actuator of the throttle valve of the 2nd chamber is controlled by a vacuum taken in the zone of the carburetor diffusers, the value of which is regulated by a thermo-pneumatic valve 18 included in the engine cooling system.
Accelerator pump
Keihin carburetor accelerator pump diagram: 2 - throttle valve of the 1st chamber; 22 - pump drive lever; 23 - pump rod; 24 - pump diaphragm; 25 - check valve; 26 - atomizer.
When the throttle valve of the 1st chamber is opened, the accelerator pump drive cam, fixed on the axis of the throttle valve of the 1st chamber, acts on the lever 22, which through the rod 23 acts on the diaphragm 24 of the pump. The fuel injected by the diaphragm is fed through the channel through the check valve 25 to the atomizer 26.
The damper spring prevents rapid movements of the throttle valve of the 1st chamber, which leads to an increase in the duration of fuel supply by the accelerator pump. After the pump diaphragm returns to its original position, the atomizer check valve closes, and the shut-off valve in the float chamber opens and the pump cavity is filled with fuel.
Keihin Carburetor Details: 1 - carburetor cover; 2 - needle valve; 3 - throttle control lever of the 2nd chamber; 4 - adjusting screw for the amount of idle mixture; 5 - restrictive screw ajar throttle valve of the 2nd chamber; 6 - axis of the throttle valve of the 2nd chamber; 7 - starting device; 8 - float; 9 - accelerator pump drive lever; 10 - main air jets; 11 - emulsion tubes; 12 - accelerator pump sprayer; 13 - idle fuel jet; 14 - main fuel jets; 15 - electromagnetic shut-off valve; 16 - quality adjusting screw (composition) mixtures; 17 - accelerator pump; 18 - carburetor body; 19 - throttle actuator of the 2nd chamber.
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