H. SCHEMATIC DIAGRAM OF CNG INJECTION SYSTEM CNG is stored in a high pressure cylinders that is mounted in boot space (rear luggage space) of the vehicle. CNG is stored at around 200 bar in the CNG cylinders. A cylinder valve is mounted on each cylinder which features multiple safety devices and a manual service valve. Gas enters to both the cylinders parallely from the filling receptacle through the cylinder valve and is fed to the regulator from the cylinders through the cylinder valves. A filler valve is used for filling CNG in cylinders. The capacity of CNG tank is 30 liters each (Total capacity is 60 liters). For filling, as the fuel flap is opened a magnetic sensor on the fuel filling dome deactivates engine cranking as a safety feature. Cranking can be done only after the CNG dispensing gun is removed and the fuel flap is shut. CNG from the CNG cylinders is fed to the CNG regulator through Stainless Steel tubes which is packaged on the underbody of the vehicle and travels along the gasoline fuel lines. The pressure regulator reduces pressure from tank storage pressure (~ 20 to 200 bar) to 4 bar. It is also connected with coolant connections that circulate coolant through pressure regulator to make up for the drop in temperature that occurs due to expansion of gas during pressure reduction. The High Pressure (HP) Sensor fitted on inlet of pressure regulator monitors pressure in high pressure line and tank,and sends signal to the ECU which is used to display quantity of CNG available in the tank on the instrument cluster. Gas from the CNG regulator after pressure reduction is sent to the low pressure filter unit where dust particles and oil from gas are removed before it goes to the gas rail. The pressure temperature sensor on the rail measures gas temperature and pressure for density calculation. Gas is then injected into the intake ports of the engine through injectors. The CNG and Gasoline Engine Management System is done by a single ECU. 1.2L REVOTRON CNG PHASE-2 ENGINE 93
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