News - Mazda
Mazda files supercharged two-stroke patent
New USPTO filing shows two-stroke Skyactiv-X engine tech with supercharger
7 Feb 2022
By MATT BROGAN
MAZDA has filed a patent with the United States Patent and Trademark Office (USPTO) for a two-stroke and supercharged version of its existing Skyactiv-X engine technology.
The reciprocating piston engine blueprints clearly show a two-stroke combustion cycle coupled with a “bolt-on” supercharger, low-load compression ignition and high-load spark ignition system.
The package is further complemented by variable valve timing, which reduces the compression ratio and, therefore, the likelihood of engine knock when the spark-ignition system is active.
While the ignition system isn’t new to Mazda – it is already offered in Skyactiv-X powered Mazda3 variants – the two-stroke design is entirely curious, as the long-established technology is typically associated with higher exhaust emissions.
The patent does hint that the two-stroke supercharged engine offers improved fuel economy, but does not say in relation to what.
In fact, the whole patent filing raises more questions than answers. Some suggest that Mazda could be making a move into the two-wheeled world or offer the engine as a range extender in a hybrid-style format.
It’s also entirely possible that the design is purely that, and that the patent filing is simply a way for Mazda to protect its IP.
The news of the patent filing follows an October report from Autocar that suggests Mazda is looking to use similar technology in its next-generation MX-5.
According to an article published by the UK website, Mazda will equip the MX-5 with the same spark-controlled compression ignition (SPCCI) engine found in the MX-30 SUV.
The MX-5 is said to be an ideal candidate for ongoing petrol power because “its relatively low sales volumes would have a negligible impact on Mazda’s European fleet-average CO2 emissions” and because the car’s diminutive size makes extensive electrification largely unviable.
Mazda said previously that its Skyactiv-X would only be used in all-new models that have been designed with associated mild-hybrid hardware.
However, owing to weight considerations, the MX-5 is expected to remain a petrol-only proposition and will likely include the Skyactiv-X’s small supercharger, which pressurises air into the combustion chamber when operating on spark-controlled ignition.
Mazda has yet to provide any official details of its next-generation MX-5 and has given no clues as to the model’s expected launch date.
However, based on the lengthy life cycles of previous MX-5 generations – most of which have remained in market for the best part of a decade – it can be expected the ‘NE-series’ MX-5 will go on sale in 2024.
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