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Simple Carburettor Fuel System for a Piston Engine

Simple Carburettor Fuel System for a Piston Engine. And how it works. Inlet. Exhaust. Tank. PISTON ENGINE – Carburettor Fuel System. COCKPIT FUEL GAUGE. Filler Cap. FUEL. 1/2. Filler Neck. E. F. FUEL LEVEL SENSOR. Tank Cavity. PISTON ENGINE – Carburettor Fuel System - Tanks. FUEL.

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Simple Carburettor Fuel System for a Piston Engine

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  1. Simple Carburettor Fuel System for a Piston Engine And how it works

  2. Inlet Exhaust Tank PISTON ENGINE – Carburettor Fuel System

  3. COCKPIT FUEL GAUGE Filler Cap FUEL 1/2 Filler Neck E F FUEL LEVEL SENSOR Tank Cavity PISTON ENGINE – Carburettor Fuel System - Tanks

  4. FUEL FUEL 1/2 1/2 E E F F PISTON ENGINE – Carburettor Fuel System - Tanks

  5. PISTON ENGINE – Carburettor Fuel System - Aircraft Tanks WHERE ARE THE FUEL TANKS IN AIRCRAFT? IN THE OTHERWISE EMPTY WING SECTIONS CI30 HERCULES

  6. 1/2 F E Cockpit Gauge Inlet Exhaust Tank Pump PISTON ENGINE – Carburettor Fuel System

  7. One-way Inlet Valve One-way Outlet Valve Diaphragm Driving Cam PISTON ENGINE – Mechanical Diaphragm Pump

  8. One-way Inlet Valve One-way Outlet Valve Diaphragm Magnetic Plate Solenoid Windings Switch Mechanism PISTON ENGINE – Solenoid Diaphragm Pump

  9. PUMP FLOW AND RESTRICTION TO FLOW IN CONTROLLER CAUSES PRESSURE TO INCREASE ‘SPUR’ GEARS FLOW OUT Flow Controller PISTON ENGINE – Gear Type Pump

  10. Air Filter Carburettor 1/2 F E Cockpit Gauge Inlet Exhaust Tank Pump PISTON ENGINE – Carburettor Fuel System

  11. Filter element – corrugated breathable paper Dirt trapped by Filter element PISTON ENGINE – Air Filter Air and Dirt Clean Air Basic Air Filter Operation

  12. Air Filter Carburettor 1/2 F E Cockpit Gauge Inlet Exhaust Tank Pump PISTON ENGINE – Carburettor Fuel System

  13. We are now going to look at how the carburettor controls the flow to the engine This is done by the: - THE FLOAT CHAMBER

  14. FUEL NOZZLE VENTURI NEEDLE VALVE AIR VENT FUEL LEVEL FUEL FEED SIMPLIFIED PISTON ENGINE FUEL SYSTEM FLOAT FLOAT CHAMBER SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  15. AIR FLOW AIR FLOW MOVING AIR HAS LOWER PRESSURE SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM AIR/FUEL MIXTUREFLOWS TO ENGINE AIR IS SUCKED THROUGH VENTURI BY….. A PISTON MOVING DOWN ON INDUCTION STROKE THE LOWER AIR PRESSURE PULLS FUEL THROUGH THE JET FUEL FLOW FUEL LEVEL DROPS SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  16. SIMPLIFIED PISTON ENGINE FUEL SYSTEM FUEL LEVEL DROPPING LOWERS FLOAT PULLING AIR INTO FLOAT CHAMBER FUEL LEVEL DROPS

  17. 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

  18. 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

  19. 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

  20. THROTTLE VALVE VALVE DISC VALVE SPINDLE LINK TO THROTTLE LEVER/PEDAL SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  21. 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

  22. 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

  23. EDGE GAPS BECOME THE VENTURI FOR THE LOW AIR FLOW AT IDLE - SLOW RUNNING JET LOW THROTTLE SETTING - CALLED ‘IDLE’ OR ‘TICK-OVER’ T CONTROLS FUEL FLOW SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  24. NEXT IS…. BALANCED AIR PRESSURE AT THE MAIN JET

  25. HERE AND HERE FLOAT CHAMBER VENT AND THEREFORE A SLIGHT VACUUM BEFORE CARB THIS WOULD CREATE A PRESSURE DIFFERENCE BETWEEN:- THE AIR FILTER CAN ALSO CAUSE RESTRICTION TO AIR FLOW SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  26. FLOAT CHAMBER VENT 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 SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  27. NEXT…. MORE EFFICIENT MIXING OF AIR AND FUEL

  28. LET’S TAKE A CLOSER LOOK AT THIS AREA HERE, ABOVE THE MAIN JET SIMPLIFIED PISTON ENGINE FUEL SYSTEM MORE EFFICIENT MIXING OF AIR AND FUEL IS ACHIEVED BY FITTING A DIFFUSER TUBE

  29. INCREASED FLOW OF MIXED AIR/FUEL AIR INLET FUEL LEVEL IN FLOAT CHAMBER AIR MIXES WITH FUEL DIFFUSER TUBE CRUISE SETTING HIGH POWER SETTING MAIN JET FUEL FEED FROM FLOAT CHAMBER SIMPLIFIED PISTON ENGINE FUEL SYSTEM AIR/FUEL MIXING IN DIFFUSER TUBE IDLE SETTING FUEL SUPPLIED VIA IDLE JET OPEN THROTTLE IDLE JET STOPS WORKING

  30. 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 pressurecapsule.

  31. FIXED END PRESSURE CAPSULE MOVING END NEEDLE VALVE CAPSULE EXPANDS IN LOWER PRESSURES AND CONTRACTS IN HIGHER PRESSURES SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  32. AT LOW ALTITUDE – HIGHER ATMOSPHERIC PRESSURE AT HIGH ALTITUDE – LOWER ATMOSPHERIC PRESSURE CAPSULE CONTRACTED CAPSULE EXPANDS HIGH FUEL FLOW SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  33. AT HIGH ALTITUDE – LOWER ATMOSPHERIC PRESSURE CAPSULE EXPANDS E AND REDUCING FUEL FLOW CLOSING FUEL ORIFICE SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM SIMPLIFIED PISTON ENGINE FUEL SYSTEM

  34. 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 pressurecapsule.

  35. Auxiliary Air Device Mixture Control Unit (Fuel Distributor Valve) Fuel Injector Warm Up Regulator Throttle Valve Air Sensor Plate Primary Pressure Valve Cold Start Valve Idle Speed Adjuster Engine Temp Sensor Air Inlet (from Air Filter) Fuel Accumulator Safety Relay Ignition Switch Filter Pump Legend High Pressure Fuel Low Pressure Fuel Fuel Tank Battery Supply Pressure Fuel Servo Pressure Fuel Electrical Signal PISTON ENGINE – Hydro-Mechanical Fuel Injection System

  36. Engine ECU 1/2 F E Injection Control Unit ‘Common Rail’ Engine Temp Engine RPM/TDC Fuel Injectors Exhaust Temp Throttle Position Forward Speed Air Temps – Inlet & Ambient Air Filter Throttle Cockpit Gauge Pressure Regulator Tank Pump PISTON ENGINE – Electronic Fuel Injection System

  37. Any Questions?

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