Honda Power Unit Hardware & Software

[gruntguru]

Re Honda video, I agree that the self ignition at the periphery is entirely independent of the spark but it wouldn't make sense to fire the spark after the HCCI event.

[Hoffman900]

Re Honda video, I agree that the self ignition at the periphery is entirely independent of the spark but it wouldn't make sense to fire the spark after the HCCI event.

I didn’t say after, just that it’s timed so they pair. You couldn’t do that without measuring cylinder pressure.

[vorticism]

Re Honda video, I agree that the self ignition at the periphery is entirely independent of the spark but it wouldn't make sense to fire the spark after the HCCI event.

I didn’t say after, just that it’s timed so they pair. You couldn’t do that without measuring cylinder pressure.

Do these pressure sensors provide measurements per stroke or as an average? i.e. at what rate do they provide measurements? Does it essentially become an average across multiple strokes, or can they tune spark timing and injector pulses in real time based on sensor data mid stroke? Are they reading at the relatively low compression pressures or at combustion pressures only?

Sidenote: why would the periphery light off first?

[Hoffman900]

Re Honda video, I agree that the self ignition at the periphery is entirely independent of the spark but it wouldn't make sense to fire the spark after the HCCI event.

I didn’t say after, just that it’s timed so they pair. You couldn’t do that without measuring cylinder pressure.

Do these pressure sensors provide measurements per stroke or as an average? i.e. at what rate do they provide measurements? Does it essentially become an average across multiple strokes, or can they tune spark timing and injector pulses in real time based on sensor data mid stroke? Are they reading at the relatively low compression pressures or at combustion pressures only?

Sidenote: why would the periphery light off first?

In-situ pressure sensors read at minimum every crank degree. They are very common in engine R&D and have been for 30 years. Most professional series engine builders (NASCAR, factory IMSA builders, Cosworth, etc) use them on dynos to map ignition timing in addition to lots of other development work. You also use them to calibrate your simulation models (heat release, pumping losses, cycle-cycle variation, etc).

I don’t know how F1 measures it beyond the compression stroke and combustion event. They might skip some data to manage their data load.

I have some experience using them to correlate 1D engine sims. You can put them in exhaust and intake ports as well. Most amateurs can be set up for about $10k to start. Sensor calibration and life is a problem and adds up fast ($). You can learn more in a handful of dyno runs mapping intake, cylinder, exhaust port pressures than you could in a decade or two of just using a dyno.

Pat Symonds in his video mentioned these engines couldn’t run without them. I have heard the same from a RB Powertrain engineer in a podcast. These would represent a costly part of these engines as the sensors aren’t cheap and likely have to be replaced often (as Pat Symonds hinted at).

This all requires an immense amount of computing power. It’s a lot of data for one sensor from a single dyno run, let alone 6 cylinders for an entire session.

As for the periphery, there is a paper called “evaluation of in-cylinder mixture homogeneity in a diesel HCCI engine” that might be helpful. They specifically tak about air fuel ratio variability with an omega shape piston (which Pat Symonds cites). The paper even refers the fuel distribution in the chamber as omega shaped, with a lean center and richer periphery.

Without turning it into a dissertation, you can imagine the periphery is richer with this “omega” distribution, and the TJI jet combustion event (in the lean portion of the chamber) meets the compression induced combustion event that starts in these richer periphery regions. Ferrari has mentioned 5 injection events / a cycle. So you can imagine they’re pushing fuel into the chamber for some of these without the spark plug firing. That happens only during the TJI combustion portion.

[vorticism]

+1 Thanks, Hoff. I wouldn't be surprised if they need to be replaced often. Accuracy fall off could destroy the engine.

fwiw I understand the omega shape (omega bowl, at least) to be a reference to the crown shape which looks like four omega forms in top view. As for an omega/horseshoe fuel distribution, unless a result of injector shaping, might be due to compression forcing the fuel mix toward the periphery away from the center due to heat and inertia effects. Maybe that's common in these schema.

[Hoffman900]

+1 Thanks, Hoff. I wouldn't be surprised if they need to be replaced often. Accuracy fall off could destroy the engine.

fwiw I understand the omega shape (omega bowl, at least) to be a reference to the crown shape which looks like four omega forms in top view. As for an omega/horseshoe fuel distribution, unless a result of injector shaping, might be due to compression forcing the fuel mix toward the periphery away from the center due to heat and inertia effects. Maybe that's common in these schema.

An omega piston bowl may be less about the actual shape and more a reference about the distribution that it creates. They cite both.

[saviour stivala]

If as claimed on here compression induced ignition at the periphery of the piston is happening, it happens after the primary spark plug induced compression ignition. There is no other way to be within the rules. But the question is, How can a compression induced ignition at the periphery of the piston be controlled (controlled combustion), with the flame-front of the primary spark-plug induced combustion racing towards the said periphery of the piston. This assertion that two types of combustion at the same time are taking place and are controlled, begs the question of how two types of combustion provided they can be controlled, can be/happen faster than a single combustion. HCCI is claimed to be spark assisted, but the design also is said to require other assisting's by things not allowed by F1 rules. So HCCI is not in it's current form compatible with F1 rules.

[Hoffman900]

If as claimed on here compression induced ignition at the periphery of the piston is happening, it happens after the primary spark plug induced compression ignition. There is no other way to be within the rules. But the question is, How can a compression induced ignition at the periphery of the piston be controlled (controlled combustion), with the flame-front of the primary spark-plug induced combustion racing towards the said periphery of the piston. This assertion that two types of combustion at the same time are taking place and are controlled, begs the question of how two types of combustion provided they can be controlled, can be/happen faster than a single combustion. HCCI is claimed to be spark assisted, but the design also is said to require other assisting's by things not allowed by F1 rules. So HCCI is not in it's current form compatible with F1 rules.

Maybe send a letter to Pat Symonds. It’s an open secret. Honda has showed a video and has shared it in a Japanese publication, Pat Symonds says it’s happening and had a slide on it, Merc has hinted at it for a few years, Ferrari calls it “super fast” in reference to their combustion events.

[saviour stivala]

If as claimed on here compression induced ignition at the periphery of the piston is happening, it happens after the primary spark plug induced compression ignition. There is no other way to be within the rules. But the question is, How can a compression induced ignition at the periphery of the piston be controlled (controlled combustion), with the flame-front of the primary spark-plug induced combustion racing towards the said periphery of the piston. This assertion that two types of combustion at the same time are taking place and are controlled, begs the question of how two types of combustion provided they can be controlled, can be/happen faster than a single combustion. HCCI is claimed to be spark assisted, but the design also is said to require other assisting's by things not allowed by F1 rules. So HCCI is not in it's current form compatible with F1 rules.

Maybe send a letter to Pat Symonds. It’s an open secret. Honda has showed a video and has shared it in a Japanese publication, Pat Symonds says it’s happening and had a slide on it, Merc has hinted at it for a few years, Ferrari calls it “super fast” in reference to their combustion events.

I did not say that compression induced ignition is not happening, but because of my doubt I asked questions. I went back to the Pat Symonds ''The road to 50% efficiency'' and confirmed again that he did not say that it (compression induced ignition) is happening. What he said was that running with high compression ratio allows us to:- ''increase in-cylinder pressure and temperatures''. ''improve the fuel conversion efficiency''. ''EXPLORE new types of combustion, different from conventional pre-mixed''. ''mix of homogeneous, stratified, diffusion flame, HCCI, Spark assisted HCCI combustion''. As to Honda, Mercedes and FERRARI I have yet to come upon an official admittance that they are using compression induced ignition.

[AR3-GP]

As to Honda, Mercedes and FERRARI I have yet to come upon an official admittance that they are using compression induced ignition.

If you were, would you want to admit to it?

[saviour stivala]

As to Honda, Mercedes and FERRARI I have yet to come upon an official admittance that they are using compression induced ignition.

If you were, would you want to admit to it?

Who would not?. Up to now I know of no official confirmation by any of the four manufacturers, and from the (Pat Symonds - "the way to 50% efficiency" pushing aside 'assumptions' - a thing that is accepted as or as certain to happen, without proof. All I got was that he was exploring some of the techniques that have been employed on current F1 hybrid power units to reach 50% thermal efficiency, AS WELL as considering how such an engine could develop in the future. Assuming things beyond what he said is at least to me overtaking him. And also, a lot have been pushed out on here about ''in-cylinder' sensors. As to controllable combustion Symonds said - ''controllable combustion is achieved using an advanced ignition system''. - ''high risk of misfire when trying to ignite a mixture at ^=1.4 with a conventional spark-plug ignition system''. - ''this led to the introduction of a passive pre-chamber - a spark plug surrounded by a perforated cap''. So my final take - a spark induced compression ignition is still being used as per the rules up to now.

[AR3-GP]

As to Honda, Mercedes and FERRARI I have yet to come upon an official admittance that they are using compression induced ignition.

If you were, would you want to admit to it?

Who would not?.

You are supposed to have a spark ignition system. Why would you admit to compression ignition?

[vorticism]

The reg is worded as:

5.12.1 Ignition is only permitted by means of a single ignition coil and single spark plug per cylinder.
No more than five sparks per cylinder per engine cycle are permitted.

They might infer something from schematics and sensor readings f.e. comparing pressure sensor readings to spark timing. Regardless, can these ignition systems alter their voltage/amperage in real time? f.e. weak spark corresponding with CI, then full spark to initiate TJI; all just to provide a rules satisfying spark at the moment of CI.

[saviour stivala]

If you were, would you want to admit to it?

Who would not?.

You are supposed to have a spark ignition system. Why would you admit to compression ignition?

Yes righto. "You are supposed to have a spark ignition system" as per the rules. And that is why I stated that 'if' compression induced combustion is being used, it is happening after the start of the by the rules spark induced compression combustion. which will push the situation into "two types of compression combustions are being used at the same time". But apart from all this, back to your question, - If any of the four engine manufacturers happen to officially admit to using compression induced combustion, WHO WOULD DARE SAY IT'S NOT THROUGH. On a different note, although I was convinced of what I was saying all along, and not amused with high ended technical push-outs of magical sounded omega bowls/sensors/dyno running and what not, I didn't expect that from you (You are supposed to have a spark ignition system. why would you admit to compression ignition?) I expected you to come out and prove a manufacturer admittance to the use of compression ignition.

[Tommy Cookers]

"using compression induced ignition" .......................
what's that ?

all ignition is compression induced
the spark ignition system wouldn't trigger ignition unless the mixture had been compressed
(also - electric ignition sparks can be produced without electromagnetic induction)

so perhaps the term compression-initiated should be used ?


and remember - to deter CI the fuel rules demand (or demanded) a minimum octane number of 75