The combustion of hydrogen to power a vehicle rather than feeding it through a hydrogen cell to produce an electrical current, has taken another step forward with Bosch announcing that it has developed a high pressure injector.
However, earlier this year, JCB announced that, for the time being, its clean sheet hydrogen engine design was to rely on the induction of a hydrogen air mix rather than have the gas directly injected into the combustion chamber.
One gas, two solutions
These are two rather distinct approaches to the challenge of ensuring a correct fuel/air mix with JCB claiming that hydrogen requires a total rethink on how an internal combustion (ICE) engine works.
Bosch feels that it can bring hydrogen to existing diesel engines with purpose designed injectors.
Bosch noted that the biggest obstacle to overcome with direct hydrogen injection is the lack of lubrication within the injector that diesel fuel provides in conventional systems, a major consideration as it is estimated that an injector may operate around a billion times or more during the life of an engine.
The company claims that it has overcome this problem through careful design of the injector and advanced coating technologies, granting the components a life comparable to that of existing items.
Keeping to the familiar
By doing so, it means that the fundamental structure of the engine, as well as the fuel, air-supply, and exhaust systems, already in use on existing engines, along with a large number of other familiar system components, can still be used on hydrogen powered engines.
More than 90% of the development and manufacturing technologies needed for the hydrogen engine already exist.
Jan-Oliver Rohrl, executive vice-president responsible for commercial vehicle powertrains noted:
It “allows us to maintain large parts of our value chain – and applies to the aftermarket as well. In addition, the hydrogen engine consists primarily of steel and aluminium, which reduces dependencies on critical raw materials and their supply chain."
This new technology does not displace Bosch’s interest in the low pressure systems it already manufactures, and it will continue to offer these products for converting existing ICE engines to hydrogen power.
Purpose designed hydrogen engine
Meanwhile, JCB is of the opinion that for the gas to work in an ICE engine, then a new approach needs to be taken, not only in creating the correct fuel air mix but also the actual design parameters of the engine itself to reduce nitrogen oxide (NOx) emissions.
JCB engineers have achieved this by reducing the temperature and compression ratio of the company’s hydrogen engine which, it claims, eliminates NOx production altogether and so dispenses with the need for any exhaust gas treatment, simplifying the installation and reducing costs.
With the reduction of the compression ratio comes the need for spark ignition, making it more akin to a petrol engine rather than a diesel which may come as something of a culture shock to operators of off-road vehicles.
JCB already has prototype off-road machines running in the real world and is refining its engine, which is based on tried and trusted technology.
On the other hand, the Bosch system has only just been introduced to the world and relies on new coatings and a sophisticated redesign of the injector body.
