Mahle details hydrogen jet injection system

The Mahle Jet Ignition system makes lean, high-compression hydrogen combustion possible

Mahle Powertrain is supporting Liebherr Machines Bulle with research related to development of a hydrogen-fuelled internal combustion engine.

Specifically, the work involves use of Mahle’s prechamber jet ignition (MJI) system. Using this system, a mix of hydrogen and air can be ignited and burned at a high compression ratio, making the combustion efficient and stable.

The system is described as ‘paving the way for hydrogen generated in climate-neutral processes to be used in heavy-duty and off-road applications’.

To achieve stable operation with a high compression ratio, while also avoiding engine knock and pre-ignition, engines need to be operated with excess air. The energy from a conventional spark plug is not sufficient to ignite such a mix.

MJI solves the problem by burning a small amount of ignitable mixture in a pre-chamber cylinder. The resulting gas plasma is passed through small openings into the main combustion chamber and, due to its high energy content, rapidly and evenly ignites the main gas mixture.

Tests with H966 and H964 engines from Liebherr have delivered ‘excellent results’ in terms of speed, performance and emissions.

Hydrogen engines are ideal for high load cycles with sudden load changes. Plus they can manage heat, dust and vibrations. This gives them a distinct advantage over fuel cells in off-road applications.