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Nissan Motor Company has announced a new type of gasoline engine

• gervase 10y ago
  This should probably link to the original Reuters article: http://www.reuters.com/article/us-autos-japan-nissan-engine-idUSKCN10P0IK?il=0 http://www.reuters.com/article/us-autos-japan-nissan-engine-...
• vmarsy 10y ago
  Interesting news, The Reuters article[1] they cite has more content than the current article[2], but even the Reuters article looks very PR-like. The TLDR appears to be: The new engine uses variable compression technology, which [allows] at any given moment to choose an optimal compression ratio for combustion. > The [new VC-T engine] averages 27 percent better fuel economy than the 3.5-liter V6 engine it replaces, with comparable power and torque. Nissan says the new engine matches the diesel engine in torque. It will be officially unveiled at next month's Paris motor show [1] http://www.reuters.com/article/us-autos-japan-nissan-engine-idUSKCN10P0IK?il=0 http://www.reuters.com/article/us-autos-japan-nissan-engine-... [2] http://www.thedailynewsgrabber.com/nissan-on-gasoline-engine-breakthrough-diesel-obsolete/ http://www.thedailynewsgrabber.com/nissan-on-gasoline-engine...
• watmough 10y ago
  Any way to know how they accomplish the variable compression?
  • qbrass 10y ago
    https://www.google.com/patents/US7165517 https://www.google.com/patents/US7165517
    • Animats 10y ago
      Oh, so that's how it works. See Fig. 2 of the patent. It's a lot like the Peugeot MCE-5, an earlier variable-displacement engine. The Nissan mechanism looks simpler and seems to take up less space inside the engine. Maybe that will make this workable. Variable-displacement isn't new, but previous attempts were mechanically clunky. It adds extra moving parts to the highest-load path in an engine - the piston to crankshaft connection. It has to deliver large benefits to justify the costs and problems that implies. Most engines already have knock sensors. They're used to adjust fuel/air ratio and spark timing to just above/after where the engine starts to knock. A few engines adjust valve timing while running, which is also complex mechanically, but not as difficult as adjusting compression. Now there's another variable to tweak. It may take a machine learning system to tune such an engine. All those interdependent variables to adjust make that a hard problem. Different values required based on engine speed, load, temperature, fuel consumption, and emissions outputs. All this is usually expressed as precomputed tables which are interpolated within the engine controller. Those tables have to be developed somehow.
  • stillworks 10y ago
    A couple of questions purely out of curiosity... - Will the ignition need to be cut off before the ratio change happens ? - Will this apply the change to all the cylinders at the same time ?
• AmVess 10y ago
  SAAB was working on one of these years ago before GM flew that company into the ground. This link gives you an idea of how it works. https://en.wikipedia.org/wiki/Saab_Variable_Compression_engine https://en.wikipedia.org/wiki/Saab_Variable_Compression_engi...
  • AmVess 10y ago
    And a youtube vid: https://www.youtube.com/watch?v=oxR-3Un6WkU https://www.youtube.com/watch?v=oxR-3Un6WkU
  • tedunangst 10y ago
    Variable compression? So logical next step is variable octane, right? One tank of 87 and one tank of 93, dynamically mixed in response to changing compression ratio. :)
    • gcb0 10y ago
      not sure if joking or not, but the injection map on your ecu does that.
      • tedunangst 10y ago
        If only my car had an 87 tank...
      • Unklejoe 10y ago
        I think you are incorrect. Most production cars (all that I know) have only a single fuel tank, thus nothing to mix.
        • asimuvPR 10y ago
          I think the point of the person you replied to is that any variation in octane is handled by the fuel injection system. This renders having two tanks unnecessary (unless you require more distance between fill ups).
• shawkinaw 10y ago
  From the (much better) Reuters article [0]: > The higher the ratio, the more efficiently the engine works, producing better fuel economy and, with the addition of a turbo-charger, more power. > Traditionally, design engineers had to fix a gasoline engine's combustion compression ratio, essentially deciding whether to go for power or economy. Everything gets better with higher compression ratio, so where's the compromise? As I understand it, the only reason engine makers don't crank the ratio as high as possible is to avoid knocking. [0] http://www.reuters.com/article/us-autos-japan-nissan-engine-idUSKCN10P0IK?il=0 http://www.reuters.com/article/us-autos-japan-nissan-engine-...
  • Aelinsaar 10y ago
    The drawback is that higher compression ratios require higher octane fuels. Nissan claims to have solved this by some kind of intelligent feedback system that allows them to control compression ratios on the fly. Presumably the compromise there is that it will require more moving parts, be expensive, and may come with issues of its own. Variability in something like a combustion chamber is a cool idea, so is variability in the angle of turbo vanes. The issue is how you do it, affordably, and in a way that lasts the way that consumers expect from their cars.
    • paulmd 10y ago
      The obvious precedent for variable-pitch blades are variable-pitch propellers on aircraft and helicopters. I don't want to say it's a solved problem for turbos, but there is almost a century's worth of prior art on the topic. That's one of those things that (in hindsight) really makes you wonder what took so long to think up. https://en.wikipedia.org/wiki/Variable-pitch_propeller https://en.wikipedia.org/wiki/Variable-pitch_propeller
      • seanp2k2 10y ago
        Because it has to be cheap and reliable at 1000*C for 200,000 miles over 10 years while constantly accelerating to 280,000RPM and decelerating with no oil or cooling air circulating when the car is stopped. https://garrett.honeywell.com/products/how-a-turbo-works/ https://garrett.honeywell.com/products/how-a-turbo-works/ http://www.epi-eng.com/piston_engine_technology/turbocharger_technology.htm http://www.epi-eng.com/piston_engine_technology/turbocharger...
• brownbat 10y ago
  I have a lot of respect for Nissan's engineers, but somewhat less respect for their lawyers, who hounded Uzi Nissan for a decade trying to get him to turn over his domain. http://www.nissan.com/Lawsuit/The_Story.php http://www.nissan.com/Lawsuit/The_Story.php Cybersquatting is obnoxious, but once they found out it was the guy's actual name, and that he was using it to run his own business, they should have just accepted he had a right to the site and worked to buy it from him or moved on.
  • bmh_ca 10y ago
    Lawyers are tools. (Being one, I feel I can say so, with a humble degree of confidence.) Certainly there's a give-and-take between lawyers giving advice and clients taking it, but by the "big X" their lawyers essentially do what they are told - lest the big client move elsewhere. All to say: Lawyers doing a bad thing are often a symptom of an internal disease or conflict. Which is to summarize a whole host of conflicting emotions: I'm slightly defensive about the profession, wholly sympathetic to the outcomes of wielding lawyers to achieve evil ends, and biased by personal experience – but nevertheless appreciative of comments, like this, that highlight the responsibility that lawyers bear to not only advise and act but to represent the reputations of institutions.
    • brownbat 10y ago
      Fellow attorney, I know how it feels to be defensive about the profession. So I should have said I'm less than enthused with their legal strategy, rather than placing blame on a specific group of people. GC definitely has an obligation to provide guidance on legal strategy before following the board's demands, and maybe they did so. Impossible to say where things broke down in this case.
    • jmus 10y ago
      I had to chuckle at your first sentence. Over here (UK) 'tool' is often used in slang as a derogatory term for a person, effectively likening them to an obvious part of the male anatomy...
    • temac 10y ago
• reidacdc 10y ago
  I am far from an expert, but there are two ways I know of to do something like variable compression, one is that Saab technique already mentioned, where the cylinder head is displaced to change the size of the combustion chamber. The other related scheme is the Atkinson cycle: https://en.wikipedia.org/wiki/Atkinson_cycle https://en.wikipedia.org/wiki/Atkinson_cycle The wiki page shows a complicated mechanical arrangement for having a smaller intake volume vs. expansion volume, but the "poor man's" way to do this is to just keep the intake valve open for the first part of the compression stroke. The upside is that you can then adjust the effective compression ratio with valve timing. The downside is that it reduces the intake manifold vacuum by blowing back some of the intake air, not sure how that's handled. Don't know what the Nissan guys are doing.
  • hvidgaard 10y ago
    This is what Mazda is doing with their Skyactive-G engines if I'm not mistaken. It works reasonably well.
• kposehn 10y ago
  More information: http://www.autoblog.com/2016/08/14/infiniti-vc-t-engine-variable-compression-official/ http://www.autoblog.com/2016/08/14/infiniti-vc-t-engine-vari...
• asimuvPR 10y ago
  Here is a simple explanation gathered from this image http://o.aolcdn.com/hss/storage/midas/de3e84cf46030cd7b3ea39900a1fa7ba/204201576/image1+%281%29.JPG http://o.aolcdn.com/hss/storage/midas/de3e84cf46030cd7b3ea39... : The difference from a conventional engine is that the engine stroke is increased or decreased automatically. The stroke is the distance the piston travels up and down in order to turn the crankshaft. A shorter distance that is closer to the combustion chamber increases the compression ratio because there is less space for the fuel/air mixture. When the system is operating in low compression mode the piston travels more and does not reach as high. The combustion chamber then ends up being farther away and a lower compression ratio is achieved. What is novel about this approach is how the combustion chamber was left in the same place. Past efforts by SAAB had the engine head moving the combustion chamber away from the pistons. This drastically changes the characteristics of the combustion process. Something that makes emissions control challenging. Any power loss due to a dynamic combustion chamber is removed by pressurising it with a turbocharger, just like Nissan did. Possible issues with this design could be: - Uneven wear of the cylinder bore due to the piston travel being dynamic. - An overboost condition during a high compression cycle could damage the mechanism and even crack the engine block. - Increased NHV due to regular wear and tear making its way into the valvetrain and transmission input shaft. This is a good effort and I hope Nissan is able to pull it off. Make sure to wait two years before you buy a vehicle with this technology. Dont be the guinea pig. :)
  • themodelplumber 10y ago
    > Make sure to wait two years Haha, this reminded me of a friend who did a summer engineering internship with a U.S. automaker. He came back and related one of the most important things he learned: "never, ever buy a first-run car." I remember hearing him tell about tolerances still being adjusted after all these cars had shipped, cringing to think of all the problems that could cause.
    • creshal 10y ago
      Engine control computers are even more fun. A friend of mine works for Audi's/VW's supplier, and honestly my biggest surprise about the emission scandal was that the code actually worked. (They had to write their own linter, because they need to ship slightly broken code written by code generators, and last I heard Windows XP is still part of the compilation chain…)
• Sanddancer 10y ago
  I'm curious as to what, if anything, would preclude variable displacement from being used in diesels as well as petrol engines. Diesels also have performance/economy tradeoffs like this gasoline engines, so it stands to reason that tweaking compression should give similar benefit. I've got a feeling that rumors of diesel's impending demise are greatly exaggerated.
  • dredmorbius 10y ago
    Diesel's fatal flaw is particulate emissions. Attempts to mitigate those, without cheating (e.g., VW), have proven difficult.
    • Sanddancer 10y ago
      Volkswagen cheated to try to get a less expensive system in place. DPFs and urea injection are pretty well proven technologies and work pretty well.
      • Reason077 10y ago
        They work well enough on new vehicles coming out of the factory. The real problem is 5-10 years later when these systems need repair or replacement. For many the economic temptation to have them "nulled" is too great (fuel efficiency is improved by removing the DPF) - and that once-clean diesel is now a toxic, polluting nightmare. This is a huge problem in the UK - and why we need to phase out diesel in private/light motor vehicles.
        • icebraining 10y ago
          How do they pass the emissions test?
          • Reason077 10y ago
            In the UK, there is no emissions test for particulate or NOx emissions, other than the subjective "does it emit visible smoke?". A visual inspection for the presence of the DPF is required, but this is easily defeated by installing a look-alike "null" filter. The people doing the MOT testing can be pretty shady anyway. Since any mechanic can operate as a testing facility, it's often the same people who remove DPFs that will then pass them in the MOT inspection.
• userbinator 10y ago
  Despite claiming they could replace diesels, I don't see any real numbers other than comparisons with their own gasoline engines. For internal combustion engines, the most efficent are still two-stroke diesels, which can have thermal efficiencies of over 50%: https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption#Examples_of_values_of_BSFC_for_shaft_engines https://en.wikipedia.org/wiki/Brake_specific_fuel_consumptio... Seeing as this design includes several more moving parts than conventional ones, it's an open question how much reliability and longevity are affected; I remember reading in a book that over the years many have tried to make more efficient engines and succeeded in achieving that goal, only to be let down because of real-world reliability issues.
  • HNSucksAss 10y ago
    The article doesn't explain what this has to do with diesel at all. Why the emphasis on replacing diesel with this technology?
• alacombe 10y ago
  How are they preventing engine knock ? At 14:1 compression you'd have to be running premium gas, which would pretty much cancel the efficiency saving, in a $$ perspective.
  • crypto5 10y ago
    Mazda has 14:1 for regular gas.
  • Unklejoe 10y ago
    I think direct injection allows engines to run higher compression ratios without knocking. I'm not sure exactly why, but I assume it's because the fuel sprays directly on top of the piston which could allow it to cool any hot spots which would have normally caused detonation.
    • jschwartzi 10y ago
      The fuel probably has to fully vaporize before it can ignite. This happens in the manifold for a normal EFI, or in the carburetor for an older engine. There's some short period of time that this is happening, and so if you time the injection to happen with enough time to vaporize the fuel before ignition it probably doesn't have enough time to pre-ignite before spark. This is speculation.
  • asimuvPR 10y ago
    Direct injection makes a significant difference by delivering cooler fuel at the correct timing point. The fuel is also delivered at a higher pressure and with better atomization.
  • micaksica 10y ago
    Don't advance ignition timing so far at 14:1 compression, and DI helps.
  • Gibbon1 10y ago
    Not sure, but would assume a gas engine can run with a higher compression ratio when under partial load than full load. If you can increase the compression ratio on the fly then you can keep the compression ratio at optimum over the whole power band. Goes double if you have a turbo since the boost provide by the turbo goes from nil to lots at the high end of the power band. I think there isn't much improvements to be had for engines at full power. But lots of room for improvement at partial power. Interesting bit, hybrid cars have really low emissions. Which says to me they're avoiding running their engines at power/rpm ranges that create high emissions.
• jacknews 10y ago
  This looks cool, but complicated. The problem addressed seems to be that turbocharged (and supercharged) engines are sub-optimal at lower powers. IMHO mild electric hybrids, or full serial electric hybrids would be a more elegant solution - only run the combustion engine when full power is needed, and use the electric motor otherwise. "full power" could be used to top the battery if it's not all required for motion.
  • dclowd9901 10y ago
    Would an electrically powered, computer-controlled turbo be silly?
    • HNSucksAss 10y ago
      I've wondered that too, primarily in the context of reducing or eliminating turbo lag by spinning up the thing electrically.
    • l0neranger 10y ago
      Audi is working on a type of electric turbocharger that spools the turbo ahead of the exhaust gas pressure, to eliminate lag . VW is working on one that uses an air compressor to pre-spool the turbo charger. And Eaton has an electric assisted supercharger that helps the supercharger spool, it can also can start the engine, and recover energy from engine braking. I'm wondering if something like stored kinetic energy like that on the Audi e-tron (a carbon vacuum sealed flywheel) could also be used to ram air into the intake, and how much resistance the air would have against the stored energy.
    • asimuvPR 10y ago
      Not at all. Problem is that ir has been an uphill battle to develop such technology. The energy required to move a turbo compressor fast enough ti generate boost is very high. A hydraulic approach has also been under works but proved challenging. Although Garret has promoted turbochargers with embedded motors to speed up the compressor speed and reduce lag.
    • ArkyBeagle 10y ago
• andrewvijay 10y ago
  "tarnished by Volkswagen's (undefined) emissions cheating scandal." Dear Reuters time for you guys to use flow in your js code.
• JumpCrisscross 10y ago
  > "Increasing the fuel efficiency of internal combustion engines is critical to automakers. Not all consumers will accept a battery electric vehicle solution. That's the thesis?
  • deleted 10y ago
    [deleted]
• Annatar 10y ago
  This is still using ignition timing and spark plugs. Additionally, the connecting shim and the timing advancer/retarder introduce not one, but two points of failure. Thanks, but no thanks: I'll just stick to my simple (by comparison) direct injected turbo diesel cars. When there is a gasoline engine which can ignite the fuel without spark plugs and ignition timing, that'll be the right solution. mazda experimented with this (see "VCCI"), but it never made it into production, because it's not a trivial problem to solve. This Nissan patent is a mechanical engineer's equivalent of a duct tape hack. Or we could just ditch this entire nonsense with pistons and optimize the Chrysler's super simple turbine car engine until it matches today's exhaust emission regulations. This was a tough problem to solve in 1978, but should be doable now with a particulate filter. And that engine isn't picky: since it's a turbine, it'll run on anything that's combustible, from filtered cooking oil to cologne. https://www.youtube.com/watch?v=b2A5ijU3Ivs https://www.youtube.com/watch?v=b2A5ijU3Ivs
  • Neil44 10y ago
    Disesl engines have very fine control of ignition timing via injection timing which is now very complex. There are tiny pilot injections and multiple short injections over a carefully controlled length of time so I don't agree that needing to time a spark makes spark ignition a more complex and by implication worse solution.
    • Annatar 10y ago
      First of all, timing by injection is still simpler than timing by spark: in gasoline engines, the computer must time both the injection and the ignition. Second, timing by spark means that spark plugs are necessary, so that is more parts, and more parts means higher probability of failure. Third, spark plugs are needed to start a chain reaction of igniting fuel, because gasoline fuel is volatile enough as not to be combustible. Gasoline fuel is not flammable, but the vapor is, did you know that? That's what makes it volatile as far as combustibility, otherwise we would have self igniting gasoline engines by now.
      • Neil44 10y ago
• SixSigma 10y ago
  In economics, the Jevons paradox occurs when technological progress increases the efficiency with which a resource is used (reducing the amount necessary for any one use), but the rate of consumption of that resource rises because of increasing demand. https://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox
• tonylemesmer 10y ago
  So if this engine changes the compression ratio (the amount the mixture is compressed) how is all this complexity better than a supercharger which changes the amount the air is compressed? Surely increasing the compression of the mixture and compressing the air before it goes in is pretty much the same thing? Except...that all that variable stroke length mechanism is a lot more complicated, and patentable?
  • ruste 10y ago
    Higher compression ratio allows better fuel efficiency. Supercharging forces more fuel and air into the same cylinder.
• Rexxar 10y ago
  It will interesting to see if this can be combined with electric power to have a very efficient hybrid engine.
• jalada 10y ago
  > The turbo-charged, 2-liter, four-cylinder [VC-T] engine averages 27 percent better fuel economy than the 3.5-liter V6 engine it replaces. You don't say.
  • gmac 10y ago
    ... with comparable power and torque.
  • rwmurrayVT 10y ago
    I'd like to hear a bit more about their definition of "comparable power and torque".
• Neil44 10y ago
  The way that makes most sense to think about this to me is in terms of dynamic compression. At full throttle the turbo is shoving a large mass of air into the cylinder for every firing. The compression ratio has to be fixed lower to control detonation under these circumstances. At light throttle / cruise there is now hardly any mass of air in the cylinder, so although mecanically nothing has changed (same / fixed compression ratio) we are hardly compressing the air at all and we're giving away a load of efficiency for that reason. The ability to up the compression ratio at cruise / light throttle claims some of that basic efficiency back.
• codeulike 10y ago
  This is all moot. Battery technology and charging infrastructure for EVs will improve so much over the next 5 to 10 years that engines running on dinosaur juice will no longer be worth the hassle for mainstream vehicles.
  • lutefisk 10y ago
    So all companies related to gas technology should just close up shop? Something that may or may not work is on the horizon, so all the engineers that have been researching gas technology for years should throw in the towel and quit? There is no chance that electric overtakes gas in 5 years.
    • codeulike 10y ago
      er, electric cars work fine. They just need to get cheaper and have longer range. That will happen easily in the next 5 to 10 years.
      • barney54 10y ago
        ...But it hasn't happened in the last 100 years--it also hasn't happened over the last 5-10 years. The Nissan Leaf, for example, is over 5 years old. There are good reasons why EVs haven't dominated yet--cost, range, flexibility, etc. Battery technology hasn't changed all that much either: http://www.cnet.com/news/why-batteries-arent-getting-better/ http://www.cnet.com/news/why-batteries-arent-getting-better/ Someday EVs may dominate, but it's doubtful that will happen in the next 5-10 years unless there is a large technological leap.
  • CWuestefeld 10y ago
    Downvoted, so I owe you an explanation. This comment didn't add to the conversation, it diverts away from it. And to the degree that it's a related topic, all you've done is to assert your own opinions, without any substance behind it.
• nickhalfasleep 10y ago
  This is an excellent implementation of variable valve gear timing that external combustion steam locomotives have had for about a century and a half. Impressive to see it put into an internal combustion engine. Edit: looking at the posted image, they change the stroke depth of the power linkage. That plus valve timings let them customize the entire combustion cycle.