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posted by Fnord666 on Wednesday August 09 2017, @10:46PM   Printer-friendly
from the more-vroom-per-mile dept.

Submitted via IRC for AndyTheAbsurd

Mazda Motor Corp said it would become the world's first automaker to commercialize a much more efficient petrol engine using technology that deep-pocketed rivals have been trying to engineer for decades, a twist in an industry increasingly going electric.

The new compression ignition engine is 20 percent to 30 percent more fuel efficient than the Japanese automaker's current engines and uses a technology that has eluded the likes of Daimler AG and General Motors Co.

Mazda, with a research and development (R&D) budget a fraction of those of major peers, said it plans to sell cars with the new engine from 2019.

"It's a major breakthrough," said Ryoji Miyashita, chairman of automotive engineering company AEMSS Inc.

[...] A homogeneous charge compression ignition (HCCI) engine ignites petrol through compression, eliminating spark plugs. Its fuel economy potentially matches that of a diesel engine without high emissions of nitrogen oxides or sooty particulates.

[...] AEMSS' Miyashita said a key issue would be how smooth and responsive the engine is.

"Is it jerky? If so, that would pose a big question when it comes to commercializing this technology." he said. "Hopefully Mazda has an answer to that question."

Source: http://www.reuters.com/article/us-mazda-strategy-idUSKBN1AO0E7


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  • (Score: 0) by Anonymous Coward on Thursday August 10 2017, @04:17AM (3 children)

    by Anonymous Coward on Thursday August 10 2017, @04:17AM (#551449)

    There are a ton of differences between Diesel and Otto cycle engines. I took courses on the very subject back in college.

    Diesel runs higher compression. But the fuel has a LOWER energy density. Diesels simply inject more fuel to get more power, up until the maximum fuel richness.

    Gasoline has a higher density. However, the THROTTLE creates a constant vacuum loss on efficiency. They have to run the right mixture always (within reason, they still go slightly RICH when WOT. Why rich? Because it's the maximum chance of maximum gas molecules finding an oxygen molecule. If it were 1:1 stiocheometric, many gas molecules would bump into gas molecules before the time is up. Which is also why older cars will "pop" in the exhaust... pockets of hot gas never got to meet their oxygen counterpart. Too many sausages, not enough buns. However, once they hit the exhaust, they finally find their mate and bang out a good one.)

    Back to the point, advantage of HCCI is that they can get rid of the biggest flaw of Otto engines... the throttle.

  • (Score: 0) by Anonymous Coward on Thursday August 10 2017, @04:24AM (1 child)

    by Anonymous Coward on Thursday August 10 2017, @04:24AM (#551454)

    Diesel has lower energy density? Which "college" did you go to?

    • (Score: 0) by Anonymous Coward on Thursday August 10 2017, @04:39AM

      by Anonymous Coward on Thursday August 10 2017, @04:39AM (#551464)

      Liberty University? Praise Jesus! Diesel is communist.

  • (Score: 3, Interesting) by shortscreen on Thursday August 10 2017, @06:39AM

    by shortscreen (2252) on Thursday August 10 2017, @06:39AM (#551498) Journal

    You are correct but I am still not sure what the breakthrough is here.

    Diesels don't have a throttle because they run lean at low loads. As GP pointed out, running lean produces more NOx (for either gasoline or diesel) (hence the VW diesel emissions fraud).

    Gasoline engines without a (conventional) throttle have already been around for a while. Instead of a butterfly valve in the intake, they use their variable valve timing/lift system to limit opening of the intake valve(s). So instead of pulling vacuum on the whole intake it's only inside the cylinder. Pumping losses inside the cylinder can additionally be reduced with EGR or Miller cycle.

    Raising the compression ratio of a gasoline engine is generally good for efficiency but beyond a certain point it causes problems. The main one of course is detonation, and there are some ways to mitigate this. Direct injection is one, but again gasoline engines with DI have already been around for a while. The higher the compression, the less freedom there is in designing the combustion chamber shape. Either you end up with domed pistons with ugly valve reliefs and the associated slow burn, reduced combustion efficiency, or you have to change the valve angles and compromise port flow.

    I'm not sure why you'd want to use compression ignition if you have spark plugs. With spark plugs, you control when the mixture ignites. With CI, you don't. Fuel takes time to burn, and being able to begin the process earlier at different engine speeds seems like the superior option. Certainly this is related to the fact that diesel engines make their maximum power at a relatively low speed (like 4000RPM or less) whereas gasoline engines with spark advance don't peak until 6,7,8000RPM or beyond.