NOX REDUCTION

EGR (Exhaust Gas Recirculation)
Exhaust Gas Recirculation (EGR) systems effectively reduce NOx emissions by recirculating a portion of the exhaust gas and mixing it with the intake air to lower the burning temperature. A computer automatically controls the EGR amount in accordance with the engine load or speed.

Continuous Control EGR System (for Light Duty Trucks)
Isuzu light duty trucks employ a continuous control system for the EGR valve and a 9-step control for the intake throttle valve. This system contributes to NOx reduction by electronically controlling the EGR volume and the intake air amount through linkage with the EGR valve and intake throttle valve.

One-Way Cooled EGR (for Heavy Duty Trucks)
In the EGR gas pipe of heavy duty trucks with intercooler turbo-charger, cooling devices are equipped to lower the EGR gas temperature before feeding it back into the engine intake. This "Cooled EGR system" results in an even cooler combustion temperature than when using an ordinary EGR system. Using a cooled EGR system raises the density of the intake air so the amount of air entering the combustion chamber increases. This helps to make combustion more complete, thereby reducing the generation of PM. Isuzu has also introduced the world's first check valve-equipped EGR system. The check valve prevents new air from entering the EGR gas pipe as well as a back-flow of gas. Also, the check valve increases the EGR recirculation amount by ensuring the gas flows in one direction. Continuous control EGR used in engine of the ELF N-Series Light Duty Truck

Source : http://www.isuzu.co.jp

CO² REDUCTION TECH

Diesel Engine Combustion Systems
The quality of combustion in diesel engines depends on how quickly and how completely the fuel mixes with the air as it is injected into the combustion chamber. Two basic systems have been devised to improve this mixing: direct-injection and indirect-injection.

Direct-Injection
The direct-injection system introduces the fuel directly into the combustion chamber. Direct-injection promotes good fuel economy, but the air swirling is not strong enough to achieve an ideal mixture with the fuel. This weakness is overcome with specially designed chambers and air-intake ports, and by the use of high-pressure fuel injection. Direct-injection diesel engines are gathering increasing popularity. They are now used in nearly all trucks with payloads of four tons or more and also in a significant proportion of passenger cars in Europe. The most popular form of direct-injection system provides a strong swirl of air in the combustion chamber to aid the air-fuel mixing process, with the fuel being injected under high pressure from four or five nozzle holes.

Indirect-Injection
The indirect-injection system is currently limited to use in passenger cars and light-duty trucks. The most popular design features a spherical swirl chamber in the cylinder head. Air is forced into the chamber by the piston and begins swirling rapidly, which promotes a good mix when the fuel is injected. A preliminary combustion of the mixture takes place and heat rises, forcing the remaining unburned fuel into the chamber at high velocity, where it mixes well with the air and undergoes complete combustion.

Intercooler-Equipped Turbocharger

Turbocharger
Intercooler-Equipped Turbocharger
A turbocharger is a mechanism that increases the amount of air supplied to an internal combustion engine at higher than normal pressure by means of a turbine powered by the exhaust gases. By allowing more air to enter the cylinder while maintaining the exhaust amount at the same level, a turbocharger can improve combustion efficiency and improve the power output.

Intercooler
An intercooler is a device that cools the supplied air, which is heated to a high temperature upon being compressed in the turbocharger. Then, it will send the cool high-density air to the cylinder.

Source : http://www.isuzu.co.jp

OTHER TECH FOR CLEANER DIESEL

Oxidizing Catalytic Converter
This catalytic converter oxidizes PM and HC from the engine exhaust by chemically converting them into harmless substances such as CO2 and water. The exhaust gas passes through a high-purification-ratio catalyst comprising precious metals such as white gold, which is installed midway along the exhaust system, and the PM and HC is significantly reduced.

Isuzu's oxidizing catalytic converter effectively removes SOF (Soluble Organic Fractions) particles such as unburned fuel in PM and HC. However, the converter does not remove the soot or carbon particles in PM.

NOx Catalyst (Under Development)
This is a catalytic device designed to convert NOx generated by the diesel engine into harmless nitrogen, water and CO2. Isuzu is currently researching deoxidizing (reduction) type NOx catalysts that employ diesel oil or urea as reduction agents. The type using diesel as the reduction agent realizes even more efficient NOx purification by utilizing a high-density carrier, which radically reforms the contact surface between the exhaust gas and the reduction agent. Before this catalyst can be employed for practical applications, however, we need to find effective ways of reducing the high oxygen concentration of the exhaust gas and the sulfur component of the diesel oil.

Continuous Regeneration DPF (Under Development)
The continuous regeneration type DPF (Diesel Particulate Filter) is a system that coverts the nitrogen monoxide (NO) in the exhaust gas into nitrogen dioxide (NO2), which can then be well oxidized in a catalytic converter, and burns the PM trapped on the filter. This system doesn' t require an energy source to support PM burning. For practical use, the sulfur contained in the fuel must be significantly reduced.

SUPER COMMON RAIL

Common rail system
Fuel under high pressure is stored in the common rail and uniformly supplied to each fuel injector. Injecting the fuel under higher pressures enables the engine to have more complete combustion, which reduces the creation of PM. At the same time, the use of multiple fuel injectors helps to prevent excessively high temperatures in the combustion chamber, thereby reducing the creation of NOx. The key to the common rail system is the precise electronic control of the fuel injection pressure, injection timing, the number of injections and the amount of fuel injected.

TURBO CHARGER

Uses the engine's exhaust gas to power a turbine, which in turn charges the cylinders with high-density air which has been compressed. This enables a higher volume of air to be taken into the cylinder and improves combustion efficiency.

Turbocharger with intercooler:
This adds a cooling device to rapidly cool intake air which gets heated as it gets compressed by the turbocharger. By charging cylinders with high-density intake air, the system is able to improve the engine's combustion efficiency, as well as the vehicle's fuel economy. while lowering its CO2 emissions.

Turbo Charger with Intercooler