Hydrogen power has been on a rollercoaster ride when it comes to addressing the needs of the modern driver. On the one hand, it offers an eco-energy solution in addition to electric vehicles and gas-hybrid engines. On the other hand, the lack of broad support, including buyers and infrastructure support, has caused the country to slowly sink into the realm of ‘what could have been’.
But Toyota isn’t ready to give up on the dream just yet. The Japanese manufacturer has been vocal and proactive in its support of the energy solution, both in the form of fuel cell technology and direct hydrogen combustion, and recently filed a patent detailing a more refined hydrogen combustion engine. Let’s check it out!
How Toyota plans to make hydrogen combustion more effective
In the diagram above we see what largely resembles a standard internal combustion engine, with a piston, crankcase and intake valves. But what sets this layout apart are the added passageways, which provide more ventilation. The patent states that combustion of hydrogen produces more moisture than combustion of petrol or gasoline operation of diesel combustion. This moisture is often expelled with the blowing gas, which, when mixed with oil, can cause a host of problems, including increased oil consumption and increased emissions of pollutants.
To combat this, Toyota engineers have incorporated additional ventilation in the form of positive crankcase ventilation (PCV) valves, one of which connects the intake manifold (28) to a one-way valve (60) leading to the crankcase (15). This valve acts as an air intake valve, which, as the name suggests, introduces air from the intake into the crankcase to aid ventilation and prevent backflow.
A separate passage (R1) gives the vented mixture a place to escape, where it meets another one-way valve (42) and multiple separators that separate the oil mist from the purge gas. A third passage (R3) functions primarily as an oil return passage returning the oil, separated from the blowing gas, back into the crankcase. During operation, these systems work together to create a more sustainable environment within the engine. This helps the engine waste less oil, produce fewer harmful emissions, and protect the system from future failures that a less efficient system may encounter.
How this patent improves the system as a whole
The inclusion of the improved PCV system, specifically the unidirectional valve connected to the crankcase from the intake manifold, helps counteract one of the disadvantages of the hydrogen combustion cycle by addressing the need for improved ventilation and moisture control. It is also designed to prevent future problems that may arise from the added PCV on the crankcase. As mentioned, the added moisture can mix with oil and, under certain climatic conditions, liquefy and form an emulsion. If the climate is particularly cold, the moisture can even freeze.
The unidirectional PCV valve connected to the crankcase uses the heat removed from the combustion cycle to heat up quickly and prevent emulsion formation. While a patent doesn’t guarantee production, it’s interesting to see Toyota pushing hydrogen technology when most of the mainstream industry has all but left this technology behind. It reflects a commitment to clean energy solutions that can only come from a pioneer in sustainability.
Source: WIPO
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