Introduction to Engine Types

 

Diesel / compression ignition engine

Petrol / Otto / Spark engine

   

 

Petrol direct-injection stoichiometric

 Bellaballoons Image

Petrol direct-injection stratified

 

Diesel / compression ignition engine

In a diesel / compression ignition engine, air is drawn into the cylinder during the intake stroke and is compressed increasing in temperature and pressure during the compression stroke. Towards the end of the compression stroke, fuel is injected into the hot and high pressure air. The heat and pressure causes pre-mixed areas of air and fuel in the fuel-injection spray to ignite / combust. The pre-mixed regions form between the start of the fuel injection event and the onset of combustion. The pre-mixed phase is then followed by the diffusion-controlled combustion phase.

 

Petrol / Otto / spark engine

In a petrol / Otto / spark engine, a homogeneous mixture of air and fuel is drawn into the cylinder during the intake stroke. Alternatively, air and fuel are both drawn into the cylinder during the intake stroke and the homogeneous mixture forms during the intake and compression strokes. This mixture is then compressed during the compression stroke and increases in temperature and pressure. Towards the end of the compression stroke a spark plug ignites the mixture and a flame propagates across the cylinder.

 

Direct injection petrol / spark engine

Direct injection petrol / spark engines are a new type of engine and are beginning to displace traditional petrol / spark engines which draw in a homogeneous mixture of air and fuel into the combustion chamber during the intake stroke. The key difference in a direct injection petrol / spark engine is that the fuel is injected directly into the cylinder rather than into the intake port. These engines can operate in either stoichiometric or stratified mode. The strategies to achieve either a stoichiometric or stratified air and fuel mixture in the cylinder may differ from one OEM product to another.

 

Direct injection stoichiometric petrol / spark engine

In a direct injection stoichiometric petrol / spark engine, air is drawn into the cylinder during the intake stroke. Fuel is injected directly into the cylinder during the intake stroke. A homogeneous mixture forms and this is ignited by the spark plug. As before, the flame propagates across the cylinder.



Direct injection stratified petrol / spark engine

In a direct injection stratified petrol / spark engine, air is drawn into the cylinder during the intake stroke. Fuel is injected directly into the cylinder towards the end of the compression stroke. The in-cylinder swirl and air flow is designed such that a richer charge of air and fuel forms in the region of the spark plug. However, in the rest of the cylinder and considering the overall air to fuel ratio in the cylinder, the engine runs in a stratified or lean manner. 

 

Multi-fuel engine

 

Multi-fuel engine 

A multi-fuel engine is one which runs on two or more fuel simultaneously. G-volution's Optimiser system allows an original single fuel engine to run on two or more fuels simultaneously. Examples of multi-fuel engines are dual-fuel concepts such as diesel-CNG, diesel-CBG, diesel-LPG and diesel-ethanol.

In a multi-fuel or dual-fuel compression ignition engine, a mixture of air and one fuel (the secondary fuel) is drawn into the cylinder during the intake stroke. A homogeneous mixture of air and fuel forms in the cylinder. This air and fuel mixture is then compressed during the compression stroke and increases in temperature and pressure. Towards the end of the compression stroke, diesel is injected into the cylinder. As per the diesel / compression ignition engine type detailed above, the air-diesel-secondary fuel mixture then ignites.

Multi-fuel or dual-fuel engines allow fuels such as CNG, LPG and ethanol to be utilised in the more efficient and higher compression ratio diesel / compression ignition engine. Traditionally, such fuels were utilised in the lower-efficiency and lower-compression ratio petrol / Otto / spark engine.

G-volution's Optimiser system provides a robust control system methodology to allow diesel engines to be converted to multi-fuel or dual-fuel engines.

 

Mono-Fuel, Bi-Fuel, Dual-Fuel and Multi-Fuel engines

 

Mono-fuel engines are ones which utilise one fuel only. Examples of this would be the traditional petrol / Otto / spark engine or the diesel / compression ignition engine. These run on 100% petrol or 100% diesel respectively.

Bi-fuel engines are ones which are able to utilise two different fuels. However, the engine uses one fuel OR the other. Examples of this would be petrol / Otto / spark engines able to run on petrol or LPG. Another example would be petrol or CNG. The engine has two different sets of fuel-injection equipment and will only use one set at a time. The engines can use 100% petrol or 100% gas.

Dual-fuel engines are the next generation of powertrains and are engines which combust two fuel simultaneously. Examples would be diesel-CNG, diesel-CBG, diesel-LPG and diesel-ethanol. These engines do not have a spark plug and require sophisticated equipment from G-volution to achieve their dual-fuel combustion. These engines offer better fuel economy, lower emissions and have lower fuel operating costs than 100% diesel engines.

Multi-fuel engines are the next generation of powertrains and are engines where a wide range of liquid and gaseous fuels can be simultaneously combusted including both fossil and new renewable fuels. G-volution leads the world in the development of multi-fuel engines.