Dynamic Skip Fire: A Technology to Improve Engine Efficiency

The concept of dynamic skip fire is a technology that aims to improve the efficiency of engines by utilizing variable cylinder deactivation. The more cylinders an engine has, the greater the effect this technology will have on fuel economy. This means that larger engines with multiple cylinders will benefit more from this technology than smaller engines.

While it's true that smaller engines tend to be more efficient and provide better fuel economy numbers, dynamic skip fire is not intended for these types of engines. Instead, its purpose is to bring larger engines closer to the same fuel economy levels as smaller engines. This is achieved by allowing the engine to run on any combination of cylinders, from one cylinder to all available cylinders.

The beauty of this technology lies in its ability to provide fully variable cylinder deactivation. This means that with a V8 engine, for example, you can run on just one cylinder or eight cylinders, depending on the situation. This allows the engine to be optimized for fuel efficiency and power output, making it an ideal solution for vehicles that require both.

So, how does dynamic skip fire work? The technology employs a locking pin system to deactivate individual cylinders. Each intake and exhaust valve is equipped with a similar locking mechanism, which can be opened or closed on command. When the deactivation arm is pressed down, the locking pin acts as a hinge, allowing the valve to open or close.

The advantage of using this system lies in its ability to minimize pumping losses. Pumping losses occur when the engine has to work hard to pull in air or push out exhaust gases. By closing off valves in cylinders that aren't firing, the engine can reduce these losses and operate more efficiently. This is particularly beneficial at low load conditions, where the engine is not producing as much power.

Another advantage of dynamic skip fire is its ability to minimize heat rejection. When an engine operates at low loads, it tends to lose heat more efficiently through the cylinder walls. By deactivating cylinders, the engine can reduce this heat loss and operate more efficiently.

The benefits of dynamic skip fire are substantial. According to Delphi, a company that has been working on this technology, users can expect a 7-15% reduction in CO2 emissions and a 10-20% improvement in fuel economy. However, it's worth noting that these numbers will vary depending on the size of the engine.

For smaller engines, such as four-cylinder models, the improvements may be less significant. This is because larger engines tend to produce more power at lower speeds, making dynamic skip fire more beneficial. In contrast, smaller engines tend to operate at higher loads and are more efficient in their natural state.

The success of dynamic skip fire will depend on its reliability and performance. While it's a complex technology, many experts believe that it has the potential to revolutionize engine design and efficiency. As with any new technology, there may be concerns about its reliability and durability, but early results suggest that dynamic skip fire is a promising solution for improving engine efficiency.

In conclusion, dynamic skip fire is a technology that aims to improve the efficiency of engines by utilizing variable cylinder deactivation. By allowing engines to run on any combination of cylinders, it provides a substantial benefit in terms of fuel economy and CO2 emissions reduction. While its success will depend on its reliability and performance, early results suggest that it has the potential to revolutionize engine design and efficiency.

"WEBVTTKind: captionsLanguage: enHello everyone and welcome in this video we are talking about dynamic skip firewhich is a technologywhich seeks to improve the efficiency ofengines and now the interesting thing about it is the larger your engine the more cylinders your engine hasthe greater the effect that this has now that's not to say that smaller engines aren't more efficientthey tend to be more efficientthey tend to get better fuel economy numbersso this technology isn't going to make you know an already super efficient small compact engine more efficientbut it will bring a larger engine closer to those fuel economy numbersso that's the goal with this technology and essentially what it does is it gives you fully variable cylinder deactivationso let's say you have a v8 enginewell you can run on one cylinder or you can run on eight cylindersor you can run on anycombination of cylinders in betweenso that's kind of the beauty of this is it allows you to run on any number of cylindersand it's the theoretical limit of what cylinder deactivation can be and how it can improveyour vehicle's fuel economy through cylinder deactivation.So how does it work first of all? And the way we're going to discuss is by closing off the intake and the exhaustvalves and there are many ways to you know stop an intake or exhaust valve from workingwe're gonna be talking about this one here using a locking pin, and so essentially we've got our cylinderwhich is going to be right here Here's our intake valvethere'll be this similar system for both the intake and the exhaust valve so you'll be blocking off both of them on command for eachindividual cylinder and so what's going on is you've got your camshaft like normaland then you have this deactivation arm and so when it's normally operating as that camshaft rotatesthere's a locking pin which acts as a hinge and you press down on thatdeactivation arm and it opens up your intake valve nothing fancy therenow oil pressure is what's keeping that locking pin in place and then when you want to deactivate this cylindercompletely and it can do this in real time. So it says you know okay, the next cylinderthat's going to fire is this one do I want to fire it yes or noand then it'll use this pin todetermine whether or not it's going to and so you'll have oil that will come in through this passageway right here it will press thatpin back so now it's no longer holding up thatdeactivation arm so now as your camshaft rotates and it hits that deactivation armit pushes it down without pushing the valve down so it comes down herepivoting more towards where the the valve is rather than pivoting where the pin isso you don't open up that valve and as a result you do not fire that cylinder and again this can be done in anycombination with any of the cylinders that you have you only use as many cylinders as you need so if you're cruising down the highwayand you really only need the power from two cylindersyou only use two cylinders and also because this can you know dynamically changewhich cylinder is firing it can actually choose an order of firing that makes sense in order for the engine to be well balanced soversus traditional cylinder deactivationcontrol methods where you may just use four cylinders or eight cylindersthis is actually going to provide you better balance and better fuel efficiency now looking at a four cylinder as an examplewhy is it more efficient to run on one cylinder than running all four cylinders for the same amount of power needed?So let's say you need to produce 25 horsepower.Why is it more efficient to run one cylinder then four cylinders each producing less than 25 horsepower?versus one producing all of that 25 horsepowerwell the reason the main reason is it comes down to having a significant reduction in pumping lossesoperating with just that single cylinderand so if you think about it from a throttle standpoint if you're just running on one cylinderyour throttle is going to be pretty wide open in order to get enough air for just that one cylinderversus if you're running a bunch of different cylindersyou don't need all that much air because you have all four of them operating so your throttle is going to be you know relativelyclosed in comparison to our example over here and with that throttle closedI meanthere's it means your engine has to work harder to pull in that air so the pumping workthat an engine is doing essentially the pumping losses is afunction of you know the pressure of the exhaust minus the pressure of the intakemultiplied by volume and solooking at it as a function of you know the pressure at the exhaust and the pressure at the intake ifyou can have that intake pressure really high as you can see this number here will decrease that means your pumping losses are lessor if you can have yourexhaust gasses your exhaust pressure really low then that means this number here is also lowerso you're pumping losses are lower so that means you'remaximizing the amount of energy if you get all of that pressure turned into useful work when you open up the exhaust valve there's nopressure left to push out of course, that's not realisticbut that's the ideal version andthen same with the intake if your engine doesn't have to work very hard to pull in that air because the pressure outside of itis already really highthen it's going to operate more efficiently and so that's the huge benefit with using just a single cylinderand having that throttle open so you reduce your pumping lossesand you don't have to have as much pumping work required versus having that throttle partially closedit's actually acting you know a lot like a damper in a way where it's requiring energyit's putting heat into the air as you pull it through requires that engine to work harder to do itanother reason is by operating at low loadsit's actually not as efficientfrom a you know within the cylinder how much heat is rejected to those cylinder wallsso you're not creating as much heat in each of those individual cylindersbut the percentage of that heat that is lost to the cylinder walls isgreater when you're operating at low load conditions rather than when you're operating at higher load conditionsengines operate more efficiently at higher loadsbut of course you're using more fuel and you're creating more power when you do that so by deactivatingseveral of the cylinders you're creating a smaller amount of power you're not creating as much efficiency lossesand you're operating so you're getting better fuel economywhile maintaining the power that you neednow as mentioned the more cylinders you have the more effective this becomes so let's say you have 16 cylindersbut you only need a little bit of power well that means if you're running all 16 cylinders your throttle is going to be nearlyclosed so you're pumping losses are hugeand you're running all 16 of those cylinders versus if you're running just a single cylinder out of those 16your you know you're pumping losses are very low and your efficiency is greater the other thing is because you are closing off the valvesusing cylinder these valvedeactivationsfor both the intake and the exhaust in the cylinders that aren't firing you don't have pumping losses because you're not actually moving any airthrough it so that's another advantage of using a system like this where you do activate it by deactivating the valvesso you don't have those pump losses associated going through those cylinders, which aren't firing nowwhat does this mean for fuel economy and for emissions?wellDelphi is saying that you can expect 7 - 15% reduction in co2 emissions and a 10 - 20%improvement in fuel economyand you know this number will be larger depending on the size of the enginesmaller four-cylinder engines aren't going to see as much of an improvement as biggerV8s V12s things like that so now that you all understand how it worksyou can let me know in the comments that because it's complicated it will fail. It's unreliableit's a dumb idea all those kinds of thingsthank you so much for watching if you have any questions or comments feel free to leave them below.\n"