Simple Carburettor Fuel System for a Piston Engine And how it works
Inlet Exhaust Tank PISTON ENGINE Carburettor Fuel System
Filler Cap COCKPIT FUEL GAUGE E FUEL 1/2 F Filler Neck Tank Cavity FUEL LEVEL SENSOR PISTON ENGINE Carburettor Fuel System - Tanks
E FUEL 1/2 F PISTON ENGINE Carburettor Fuel System - Tanks
WHERE ARE THE FUEL TANKS IN AIRCRAFT? IN THE OTHERWISE EMPTY WING SECTIONS CI30 HERCULES PISTON ENGINE Carburettor Fuel System - Aircraft Tanks
Cockpit Gauge Inlet Exhaust Tank Pump PISTON ENGINE Carburettor Fuel System
One-way Inlet Valve One-way Outlet Valve Diaphragm Driving Cam PISTON ENGINE Mechanical Diaphragm Pump
One-way Inlet Valve One-way Outlet Valve Diaphragm Magnetic Plate Solenoid Windings Switch Mechanism PISTON ENGINE Solenoid Diaphragm Pump
PUMP FLOW AND RESTRICTION TO FLOW IN CONTROLLER CAUSES PRESSURE TO INCREASE SPUR GEARS Flow FLOW Controller OUT PISTON ENGINE Gear Type Pump
Air Filter Carburettor Cockpit Gauge Inlet Exhaust Tank Pump PISTON ENGINE Carburettor Fuel System
Filter element corrugated breathable paper Dirt trapped by Filter element Air and Dirt Clean Air PISTON Basic Air ENGINE Filter Operation Air Filter
Air Filter Carburettor Cockpit Gauge Inlet Exhaust Tank Pump PISTON ENGINE Carburettor Fuel System
We are now going to look at how the carburettor controls the flow to the engine This is done by the: - THE FLOAT CHAMBER
FUEL NOZZLE VENTURI NEEDLE VALVE AIR VENT FUEL LEVEL FLOAT FLOAT CHAMBER SIMPLIFIED PISTON ENGINE FUEL SYSTEM FUEL FEED
AIR/FUEL MIXTURE FLOWS TO ENGINE AIR FLOW FUEL FLOW AIR FLOW AIR IS SUCKED THROUGH VENTURI BY.. A PISTON MOVING DOWN ON INDUCTION STROKE THE LOWER AIR PRESSURE PULLS FUEL THROUGH THE JET FUEL LEVEL DROPS MOVING AIR HAS LOWER PRESSURE SIMPLIFIED PISTON ENGINE FUEL SYSTEM
FUEL LEVEL DROPPING LOWERS FLOAT PULLING AIR INTO FLOAT CHAMBER FUEL LEVEL DROPS SIMPLIFIED PISTON ENGINE FUEL SYSTEM
FUEL LEVEL DROPPING LOWERS FLOAT FUEL LEVEL RISING FORCES THE NEEDLE VALVE CLOSED AND ALLOWS FUEL TO ENTER FLOAT CHAMBER FROM PUMP FUEL LEVEL DROPS SIMPLIFIED PISTON ENGINE FUEL SYSTEM
FUEL LEVEL RISING FORCES THE NEEDLE VALVE CLOSED FUEL IS PULLED OUT OF THE FLOAT CHAMBER ONLY WHEN ONE OF THE PISTONS IS ON THE INDUCTION STROKE SIMPLIFIED PISTON ENGINE FUEL SYSTEM
We now need to look at controlling the air/fuel mixture flowing into the engine Controlling the air/fuel mixture means controlling the engine The carburettor part which controls the flow is. THE THROTTLE
THROTTLE VALVE VALVE DISC VALVE SPINDLE LINK TO THROTTLE LEVER/PEDAL SIMPLIFIED PISTON ENGINE FUEL SYSTEM
BETWEEN THROTTLE VALVE AND ENGINE IS A PARTIAL VACUUM AND FLOW RESTRICTION THROUGH THROTTLE VALVE CAUSED BY SUCTION FROM ENGINE AIR FILTER CARB. FUEL AND AIR IS MIXED VENTURI DUE TO LOWERED AIR PRESSURE CONTROLS THROTTLE MIXTURE FLOW VALVE TO ENGINE ENGINE PULLS AIR IN DURING INDUCTION STROKE INLET MANIFOLD THE INLET MANIFOLD VACUUM CAN BE USED TO HELP APPLY THE BRAKES CALLED POWER-ASSISTING ENGINE EXHAUST MANIFOLD SIMPLIFIED PISTON ENGINE FUEL SYSTEM
THROTTLE VALVE THIS WOULD BE A HIGH THROTTLE SETTING OR FULL POWER OPEN THROTTLE ALLOWS VENTURI TO WORK AT MAXIMUM EFFICIENCY SIMPLIFIED PISTON ENGINE FUEL SYSTEM
LOW THROTTLE SETTING - CALLED IDLE OR TICK-OVER ALMOST CLOSED THROTTLE MEANS THE VENTURI DOES NOT WORK VERY WELL LOW AIR FLOW MEANS VERY LITTLE OR NO FUEL/AIR MIXING IN THE VENTURI SO AN ALTERNATIVE AND EFFECTIVE VENTURI NEEDS TO BE FOUND SIMPLIFIED PISTON ENGINE FUEL SYSTEM
LOW THROTTLE SETTING - CALLED IDLE OR TICK-OVER EDGE GAPS BECOME THE VENTURI FOR THE LOW AIR FLOW AT IDLE - SLOW RUNNING JETT CONTROLS FUEL FLOW SIMPLIFIED PISTON ENGINE FUEL SYSTEM
NEXT IS. BALANCED AIR PRESSURE AT THE MAIN JET
THIS WOULD CREATE A PRESSURE DIFFERENCE BETWEEN:- HERE AND HERE FLOAT CHAMBER VENT THE AIR FILTER CAN ALSO CAUSE RESTRICTION TO AIR FLOW AND THEREFORE A SLIGHT VACUUM BEFORE CARB SIMPLIFIED PISTON ENGINE FUEL SYSTEM
AND THE FLOAT CHAMBER IS CONNECTED TO THE CARB AIR INTAKE EQUALISING THE PRESSURE AT LOW SPEED SO THE VENT TO THE FLOAT CHAMBER IS CLOSED OFF THEREFORE PREVENTING TOO MUCH FUEL MIXING WITH THE AIR FLOAT CHAMBER VENT SIMPLIFIED PISTON ENGINE FUEL SYSTEM
NEXT. MORE EFFICIENT MIXING OF AIR AND FUEL
MORE EFFICIENT MIXING OF AIR AND FUEL IS ACHIEVED BY FITTING A DIFFUSER TUBE LET S TAKE A CLOSER LOOK AT THIS AREA HERE, ABOVE THE MAIN JET SIMPLIFIED PISTON ENGINE FUEL SYSTEM
INCREASED FLOW OF MIXED AIR/FUEL AIR/FUEL MIXING IN DIFFUSER TUBE AIR INLET FUEL LEVEL IN FLOAT CHAMBER AIR MIXES WITH FUEL DIFFUSER TUBE IDLE FUEL OPEN CRUISE HIGH THROTTLE POWER SETTING SUPPLIED SETTING VIA IDLE JET IDLE JET STOPS WORKING MAIN JET FUEL FEED FROM FLOAT CHAMBER SIMPLIFIED PISTON ENGINE FUEL SYSTEM
NEXT... AUTOMATIC MIXTURE CONTROL This is required to take into account that at higher altitude there is less air, so therefore less fuel is required. This change in fuel flow is controlled by a device that can sense the change in air pressure. It is called a pressure bellows or pressure capsule.
CAPSULE EXPANDS IN LOWER PRESSURES AND CONTRACTS IN HIGHER PRESSURES FIXED END PRESSURE CAPSULE MOVING END NEEDLE VALVE SIMPLIFIED PISTON ENGINE FUEL SYSTEM
AT LOW HIGH ALTITUDE HIGHER LOWER ATMOSPHERIC PRESSURE CAPSULE CONTRACTED EXPANDS HIGH FUEL FLOW SIMPLIFIED PISTON ENGINE FUEL SYSTEM
AT HIGH ALTITUDE LOWER ATMOSPHERIC PRESSURE CAPSULE EXPANDS CLOSING FUEL ORIFICE AND REDUCING FUEL FLOW SIMPLIFIED PISTON ENGINE FUEL SYSTEM
NEXT... AUTOMATIC MIXTURE CONTROL This is required to take into account that at higher altitude there is less air, so therefore less fuel is required. This change in fuel flow is controlled by a device that can sense the change in air pressure. It is called a pressure bellows or pressure capsule.
Auxiliary Air Device Warm Up Regulator Mixture Control Unit (Fuel Distributor Valve) Fuel Injector Primary Pressure Valve Air Sensor Plate Throttle Valve Idle Speed Adjuster Cold Start Valve Air Inlet (from Air Filter) Engine Temp Sensor Fuel Accumulator Safety Relay Ignition Switch Filter Pump Fuel Tank Battery Legend High Pressure Fuel Low Pressure Fuel Supply Pressure Fuel Servo Pressure Fuel Electrical Signal PISTON ENGINE Hydro-Mechanical Fuel Injection System
Injection Control Unit Common Rail Engine ECU Engine Temp Engine RPM/TDC Exhaust Temp Throttle Position Forward Speed Air Temps Inlet & Ambient Air Filter Fuel Injectors Cockpit Gauge Throttle Pressure Regulator Tank Pump PISTON ENGINE Electronic Fuel Injection System
Any Questions?