Starting device
When starting a cold engine under the influence of a thermostatic bimetallic spring of an automatic starter, air damper 1 (see diagram) blocks the air flow through the carburetor duct, the throttle valve 3 opens a little under the action of the drive system of rods and cams 2, providing an increase in the idle speed of a cold engine.
Under the action of vacuum in the diaphragm cavity of the starting device, an increased amount of fuel passes through the main fuel jet, which ensures the start of a cold engine.
After starting the engine, the vacuum that occurs in the intake piping of the running engine drives the pneumatic actuator 4, which opens the air damper a little. After warming up with the transition to the load mode through the system of rods and levers actuated by the throttle valve, the air damper opens slightly, which causes a depletion of the combustible mixture and ensures uninterrupted engine operation.
Idle system and transition system
Fuel taken from the float chamber through the main fuel jet 5 (see diagram) enters the well of the emulsion tubes and is supplied to the idle fuel jet 6. At the outlet of the jet 6, the fuel is mixed with air entering through the idle air jet. The emulsion is supplied to the outlet 7 of the idle system under the throttle valve through a hole regulated by a quality needle screw 8 (composition) mixture, and through the hole closed when the ignition is turned off by an electromagnetic shut-off valve 9.
When the throttle valve 3 is smoothly opened, the combustible mixture enters the vertical channel of the transition system 10, which leads to a gradual increase in the engine crankshaft speed.
The transition system of the 2nd chamber works similarly, providing an increase in the crankshaft speed as the throttle valve of the 2nd chamber opens. The transition system of the 2nd chamber is not adjustable and does not have a shut-off valve.
Scheme of the idle system and the transition system of the Pierburg 2V5 carburetor:
3 - throttle valve of the 1st chamber;
5 - main fuel jet of the 1st chamber;
6 - idle fuel jet;
7 —outlet of the idle system;
8 - quality adjusting screw (composition) mixtures;
9 - electromagnetic shut-off valve;
10 - slots of the transition system
Main dosing system
Fuel through the needle valve is supplied to the float chamber 11 (see diagram). The float hinged on the axis regulates the opening of the needle valve to maintain a constant fuel level in the float chamber.
From the float chamber, the fuel enters the emulsion tube through the main fuel jet 5 of the 1st chamber, where it mixes with the air supplied through the jet 12. Then the air-fuel mixture fills the mixing chamber formed by the small and large diffusers 13.
The main dosing system of the 1st chamber has a power mode economizer. When the vacuum drops in the zone of the throttle valve 3 of the 1st chamber, caused by a significant opening of the throttle valve, the vacuum is removed in the diaphragm cavity of the power modes economizer housing 14, the valve 15 of which, under the influence of a spring, opens the channel 16 for supplying additional fuel to the channel of the fuel jet of the main metering system 1 th camera.
The main dosing system of the 2nd chamber works similarly, except that it does not have a power mode economizer.
Scheme of the main dosing system of the 1st chamber and the economizer of the power modes of the Pierburg 2V5 carburetor:
3 - throttle valve;
5 - main fuel jet;
11 - float chamber;
12 - main air jet;
13 - diffuser;
14 - economizer power modes;
15 - economizer valve;
16 - fuel supply channel from the economizer.
Accelerator pump
Opening throttle 3 (see diagram) The cam 17 of the 1st chamber actuates the lever 18 of the drive of the accelerator pump 19 and the pump pumps the fuel sucked into the float chamber into the mixture formation zone through the check valve 20 and the atomizer 21.
Pierburg 2V5 carburetor accelerator pump operation diagram:
3 - throttle valve of the 1st chamber;
17 - thrust drive accelerator pump;
18 - lever drive accelerator pump;
19 - piston rod of the accelerator pump;
20 - check valve;
21 - accelerator pump sprayer
Pierburg 2V5 carburetor operation schemes when starting a cold engine:
1 - air damper;
2 - system of rods and cams for slightly opening the throttle;
3 - throttle valve;
4 - pneumatic actuator of the air damper.
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