MAHLE Jet Ignition®

MAHLE Jet Ignition® enables homogeneous ultra-lean combustion in modern gasoline engines.

The MAHLE Jet Ignition® system is a new combustion technology which replaces the standard spark plug in SI engines with a jet ignition chamber assembly. MAHLE Jet Ignition® facilitates the implementation of ultra lean-burn operation in gasoline engines, improving their efficiency and reducing the formation of pollutants such as nitrogen oxide and particulates.

Inside the jet igniter assembly is a small ignition chamber with a direct injector (DI) that provides a small amount of auxiliary fuel (<5% of the total system fuel) and a spark plug to ignite that charge. The ignition chamber is connected to the main chamber by a number of orifices which allow jets of partially combusted products to ignite the main charge. The smaller orifice size causes turbulence in the hot gas jets which then penetrate deeper into the main combustion chamber and cause an evenly distributed ignition effect. The main chamber is fuelled through a conventional port or direct-injection injector. With 4-8 ignition jets, depending on the application, the main charge is extensively ignited and a faster burn-through and pressure build-up is generated. Furthermore, this process allows increased compression ratios (a 4 point increase in some applications) combined with lower combustion temperatures and reduced throttling / pumping losses to achieve peak indicated thermal efficiencies up to 45%.

The MAHLE Jet Ignition® system’s combustion is much quicker than with standard spark ignition, enabling the engine to operate at optimum spark timing as the knock limit is extended significantly. In car engines, high fuel savings are achieved by the higher, almost diesel-like efficiency. Engine tests show specific consumption below 200g / kWh and significant related reductions in CO2 emissions. In addition to providing efficiency and fuel consumption advantages, MAHLE Jet Ignition® also achieves reductions in engine-out NOx emissions by more than 99 per cent in the ultra-lean area. Hydrocarbon (HC) emissions are maintained at levels equivalent to standard spark ignition operation. MAHLE Jet Ignition® (with a PFI main chamber) generates slightly elevated particulates compared to a PFI engine but these are significantly reduced versus a DI engine.

In “passive” guise, the MAHLE Jet Ignition® pre-chamber contains only a spark plug, and fuel is transfered to the pre-chamber through the nozzle orifices during the compression stroke. The operating principle of a passive system is consistent with that of an “active” system. Passive MAHLE Jet Ignition® produces shorter burn durations which reduce the tendency of the engine to knock at high loads, thereby increasing peak power and efficiency.

MAHLE Jet Ignition® is an exciting new combustion system that provides great potential for further CO2 emissions reduction in latest generation gasoline engines.

MAHLE Jet Ignition® [PDF; 561 KB]

MAHLE Jet Ignition® - Animation

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