The Hindu Business Line : Ashok Leyland develops new CNG engine for buses

Chennai, Jan. 2 Commercial vehicle major, Ashok Leyland Ltd, has developed CNG engine for buses with multi-point fuel injection (MPFI) system that can meet Euro IV emission standards. The MPFI system will inject the gas at several points into the cylinder, progressively within infinitesimal fractions of a second. In contrast, in the conventional engine, the gas-air mixture is injected at one point. Consequently, fuel burns better in the MRFI engine and, hence, it delivers more power and torque, fuel efficiency and lower emissions than the existing carburettor engine. It will also cost “significantly more” than the conventional CNG engine.

Currently, the company produces the ‘H’ series 6E, six cylinder engine for CNG buses that give maximum power of 90 kW at 2,400 rpm. The new engine offers superior power rating at 135 kW at 2,400 rpm. This 5.7-litre turbocharged inter-cooled natural gas engine meets Euro IV emission norms ahead of the mandate in India, by 2010.

Speaking to Business Line the Executive Director (product development) of Ashok Leyland, Mr M. Natraj, said the engine would be commercially manufactured beginning early 2009.

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According to a company press release, the new ‘H’ series CNG engine is the country’s first one-litre-per-cylinder in six cylinder configuration. The engine offers superior power rating (135 kW @ 2,400 rpm) with low emissions.

The CNG engine uses stoichiometric (chemically correct air-fuel ratio) combustion technology in combination with three-way catalytic converter to reduce the emissions to the lowest level possible. The MPFI system delivers the required gas quantity at the intake manifold, as per the vehicle demand even in transient operating conditions.

In addition to the MPFI, Ashok Leyland also plans to fit the CNG engines with a few other gizmos — the EGR and ECU. The exhaust gas re-circulation (EGR) used in this engine not only lowers the NOx emission but also restricts the thermal load on the engine components. EGR was introduced about four decades ago to curtail oxides of nitrogen (NOx), which when combined with hydrocarbons in the presence of sunlight, produced smog. When re circulated, the exhaust gases displace some of the normal intake charge and slows down the combustion process by few hundred degrees, thus reducing formation of NOx.

While the electronic control unit (ECU) controls the sequential gas injection and high-energy ignition systems, the plug-on coils used in the engine coupled with long life spark plug, makes for maintenance-free operation of the vehicle, the release added.

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