Carburettor

The Solex carburetor 28 PICT to 34 PICT of the former German carburetors society is downdraft carburetors with suction widths between 28 and 34 mm. Actually the carburetor would have correctly " Zerstäuber" are called, because it transfers the liquid fuel into a mixture from air and fuel droplet. After today's view carburetors are as Gemichaufbereitungssysteme outdated, there with fuel injection systems • the pollutants in the exhaust gas to be substantially reduced can, • the achievement related to the capacity rises, • Cold weather starting, warm up and transition behaviour to be improved can and • a fülligerer torque process to be reached can. Carburetors are nevertheless complex wonderworks of the technology with many mechanical and pneumatic control members, whose failure probability is accordingly high with older engines. The main construction units of a simply developed carburetor are in detail in the following pictures shown, i.e. • Air tunnel (venturi tube) with mixing chamber, • Butterfly valve, • Withdrawal pipe with main jet as well as • Schwimmergehäuse, float and Schwimmernadelventil (J), fuel connection. As necessary additional devices the Solex carburetor exhibits 28 PICT to 34 PICT the following functions: • for part-load: Luftkorrekturdüse with mixing tube, • for the acceleration procedure: Diaphragm pump (H), injection pipe (I), • for the no-load operation: Leerlaufdüse (G), Umluftabschlaltventil (e), idling speed adjusting screw (D), CO adjusting screw, • for the transition from no-load operation to accelerating: Transition mechanism (bypass drilling), • for the cold weather starting: Automatic choke with electrically heated bimetal feather/spring (A) and Starterklappe, Pulldown mechanism (B + C) • for the full load: Enrichment pipe Function: With opened butterfly valve a increased flow rate of sucked in air and thus a negative pressure develop in the air judge when sucking in the engine.

This negative pressure sucks the fuel, that before in the mixing tube with air enriched itself through the withdrawal pipe into the mixing chamber. Here itself explosive fuel/air mixture of approx. 14.7 kg of air should to 1 kg fuel (Lambda = 1) to adjust. The butterfly valve steers the quantity of the sucked in mixture and thus the engine speed. The float device keeps the supply of fuel in the Schwimmerkammer constant over the Schwimmernadelventil. As soon as the Kraftstoffstand reached its Füllhöhe, the Schwimmernadelventil locks the supply of fuel by the lift of the float. The additional devices stop the composition fuel/air mixture in the operating conditions no-load operation, part-load, accelerating and cold weather starting deviating from the basic adjustment of the lean or fatter. The Luftkorrekturdüse works against by Vorverschäumung of a over greasing with increasing opening of the butterfly valve. In the no-load operation a bypass drilling leads a small quantity additional fuel around the closed butterfly valve into the syphon. Far drillings with the types PICT-3 provide with the transition from the no-load operation to acceleration for a further dose fuel. If the driver wishes a higher acceleration, then a diaphragm pump coupled with the butterfly valve manipulation pumps a defined amount of fuel to the mixing chamber, around which mixture anzufetten. With the carburetors of the type PICT-3 the injection amount depends even on the temperature. With cold engine more fuel is injected. With cold weather starting of the engine fuel at the cold walls of the suction tube condenses, so that the mixture must be stopped fatter. This is done via temporary closing of the Starterklappe with the automatic choke. By the only little opened Starterklappe the negative pressure before the butterfly valve and more fuel rise are sucked in. After a preset time (notch K), in which the engine its operating temperature have reached should, the Starterklappe is again fully opened and the carburetor in the basic adjustment is operated. An electromagnetic circulating air turn off valve prevents a running after of the engine after switching the ignition off (starting from PICT-1). With full power, i.e. the butterfly valve is opened full, comes into force the full load enrichment. By the negative pressure, decreasing at height of the starter flap wave a ball valve is opened and additional fuel into the mixing chamber is given, in order to achieve full engine performance.