HEXA

ENGINE 74 F. Fuel System : Introduction to VARICOR System : 1. This engine uses DELPHI high-pressure pump and a common rail for supplying all the cylinders with high-pressure diesel through the electronically-controlled fuel injectors. High pressure results in better atomization which leads to complete combustion. 2. Common-rail is a key to better diesel engine performance, since more accurate high pressure injection results in more efficient fuel combustion. It also injects the fuel only when it is required thereby increasing fuel efficiency. It helps the engine to create a perfect blend of power and fuel economy. 3. The brain of the VARICOR engine is the ECU (Electronic Control Unit) which keeps the VARICOR engine functioning at its optimal capacity. It continuously receives signal from various sensors to calculate the timing and quantity of fuel required by the engine with complete flexibility. Besides the ECU also controls Engine cooling electric fans, A/C, EGR, VNT and diagnosis etc. 4. In addition to the other sensors, the ECU also receives continuous inputs from the rail pressure sensor which monitors fuel pressure. The ECU can thus keep the system pressure at an optimal value as per the engine speed, load and various operating conditions. For example, if the pedal is pressed, depending on the amount of pedal depression, the accelerator pedal sensor immediately sends a signal to the ECU. The VARICOR System has “Drive by wire” technology where in Driver demand translation is done through ECU. 5. The ECU determines the load required by the engine to meet the driver demand. It then sends a signal to the high pressure pump through the IMV (Inlet Metering Valve) to send the exact amount of fuel to common rail to meet the requirement. The Inlet Metering Valve determines the quantity of fuel required to be pumped to the rail depending on the engine speed & load and pressurizes the same thus avoiding wastage of fuel. This helps in improving the fuel consumption. 6. The ECU also tells the injectors exactly when and how much to inject, to produce the amount of power actually needed. 7. The high pressure pump has an internal lift pump to draw the fuel from the fuel tank. (In case, the pedal is released abruptly the excess fuel is recycled back into the fuel tank via the injectors, through the venturi and fuel return lines). 8. The desired amount of fuel is pumped into the common rail after taking into account the current fuel pressure (as detected by the rail pressure sensor and sent to the ECU). 9. The fuel gets distributed through the rail to the individual electronically controlled injectors into the cylinders. 10.The fuel is injected into the combustion chamber at the specified time and pressure. As a result it increases the power output and vastly enhances the fuel efficiency. 11.In addition the ECU commands the injectors to inject a small amount of fuel in to the cylinder before the main injection happens. This pilot injection helps to reduce the instantaneous combustion which causes the traditional Diesel ‘Knock’. As a consequence there is far less noise, vibration and harshness that is conventionally associated with DI diesel engines. 12.This entire process happens in tiny fractions of a second. 13.Finally to control the emission, the EGR (Exhaust Gas Recirculation) valve along with EGR cooler does its bit to reduce nitrogen oxides and particulate matter content in the emissions by effectively managing exhaust gas and unburned fuel by returning it to the combustion chamber for further combustion events. 14. The VARICOR System is equipped with Fuel filter & fuel prefilter cum s edimentor designed to filter out external particles & separate water from Diesel. The water sensor in Sedimentor gives an alarm to the Driver through a Dashboard indicator when the water level increases which indicates presence of water in fuel.