fmzambon

I'm under the impression that all of these patents are actually dead ends, in the sense that none of these will see production. This is based on the fact that patents describing features actually found in the Renesis showed up basically as the car was being delivered to the final customers.
Since we're still many months (years?) away from that moment for the new car, I can only assume that the reason to patent something now is that no further development of that thing is expected, so better patent it before anyone else may stumble on it and use it.

If this is the case, even if none of this makes it to production, that's still very good because it means that Mazda found some other solution to these problems that is even better

7Suns

Man, that's a radical design. Still makes one wonder why they hadn't tried it before, seems so simple.
Very interesting.

arghx

iTrader: (3)

the good thing about Mazda making patents is that it shows Mazda still has some resources devoted to a rotary. When Audi (which bought NSU) killed their rotary program in the early 80s I doubt they were still releasing patents afterwards.

7Suns

Ah well, after reviewing that diagram a bit closer, I see why Mazda may have been hesitant to use such a design.

The exhaust manifolds, they would be unconventional to how the 13Bs' manifolds have been arranged all these years (ports separated far from each other).

But then again, perhaps it would be an opportunity to use a true-dual exhaust arrangement.

fmzambon

In technical terms, it would be a plumbers' nightmare

arghx

iTrader: (3)

It's more complex than the current arrangement, which is sort of like an I6 engine with a counterflow (non crossflow) head (like an old Datsun I6). But that design is not much different than a V6 or V8 or a boxer or any other 2 bank engine.

fmzambon

Yeah, I know. I was exaggerating, hence the smile at the end

BLUE TII

iTrader: (9)

Mazda's next engine the Sky Activ-X Homogeneous Charge Compression Ignition is loaded up with sensors including

Cylinder pressure sensor.

And it has an onboard Ozone Generator as well.

The Secret Device That Could Be the Key to Mazda's Revolutionary Gas Engine

If Mazda implements the cylinder pressure sensor on the next rotary we should have very good knock control (though aftermarket tuning could be a headache at first).

Also, if Mazda can spend the money for an on board Ozone generator for the piston engines, maybe they can spend the money for an on board Hydrogen reformer for the rotary.

arghx

iTrader: (3)

Cylinder pressure sensors in mass produced engines aren't new. VW has glow plug cylinder pressure transducers in their diesels. They're just really expensive.

fmzambon

Having a gazillion of sensors is pretty much a must AFAIK, given how sensitive the compression ignition process is. The ECU must know as much as possible to control the engine effectively and safely.

Regarding HCCI in the rotary, the big question I have is: would this compression ignition technology work even in an engine that does not have continuously variable intake and exhaust timing and duration?
I ask because everything else should be reasonably straightforward to carry over to a rotary engine, but if the compression ignition technique developed by Mazda completely relies on continuously variable valve timing and/or duration, then it may be difficult to adopt it to the rotary.
Perhaps the high pressure air injection and/or other strategies could supplement the "stepped" intake configurations that are inherent to the rotary design, I don't know

On a side note, I'm fairly surprised that it wasn't FCA that got to the HCCI engine first with their Multiair system. That system can be used to alter the intake valve timing cylinder by cylinder and cycle by cycle, so it could allow instantaneous and precise control of the pressure inside each cylinder. And that, in turn, should be perfect to control compression ignition by just working with the intake valve timing.

BLUE TII

iTrader: (9)

I don't think the way Mazda is doing the HCCI can be implemented in a turbo rotary yet. I think they are depending on varying the the supercharger output for variable compression ratio in the SkyActiv-x engine.

I don't see boost at the low loads they are trying to do HCCI (cruise) as possible with the turbo.

But just having the combustion pressure sensor in Mazda's parts bin and available for their halo car will really help turbo rotary reliability as it can predict/eliminate knock and protect the apex seals.

Supplemental Hydrogen injection is easy/cheap to implement in the rotary however. If the cost of the compact on-board Hydrogen reformer is feasible.

arghx

iTrader: (3)

I read the patent that the article was referring to. There are a lot of details in there that the writer of the Road & Track article skipped over or didn't see the important of.

The HCCI piston engine has a lean burn area, and that's where the O3 generator is used, to stabilize the combustion and reduce the NOx so that aftertreatment isn't needed when running super lean (Lambda > 2.4). There are a lot of things to make the HCCI work when the engine is cold. A lot of it has to do with controlling gas temperature using hot EGR or cooled EGR, and retarding the injection timing.

The valve timing diagrams in the patent are mostly relying on a 2 step cam profile for both intake and exhaust events. On a rotary you could do the same thing (like the aux ports on a 6 port n/a engine) but you lose the ability to continuously vary the opening and closing timings. All the EGR and other stuff they are doing could be done on the rotary.

With MultiAir, it's not nearly as precise as initially advertised years ago. Half those trick valve timing things they say in marketing it doesn't actually do (like "multi lift"), because it can't be controlled well in a car with varying oil temperatures and driving conditions. What it does do well is late intake valve closing (Miller cycle) and early intake valve opening (for overlap).

All MultiAir engines have fixed exhaust profiles. That's a big constraint, unless they redesign the basic concept. The other concern is the nature of hydraulic actuation of the valves. There is a sophisticated model that calculates when the solenoids should engage and disengage to achieve a target valve opening and closing angle, and it's pretty sensitive.

Change the oil grade, they run different. Cold start? Runs different. Run them hot and get oil aeration, they run different. That's fine for basic stuff like Miller cycle (run the cam out to the end of the profile, closing about 80-100 degrees ABDC), but when you are talking about really precise cycle to cycle control it's not so straightforward.

fmzambon

I wasn't aware that the system was so imprecise, even though it makes sense in hindsight. Perhaps using a specific fluid rather than engine oil could solve part of these problems?
And as for the exhaust valves, it seems to me that the same system could be applied to them as well, provided that one physically manages to package the system needed to actuate them in the cylinder head. But maybe there's some other limitation that prevents its use on the exhaust side, such as the heat being transmitted to the fluid through the valve stems?

arghx

iTrader: (3)

This is where the big picture comes in. Do you dump a ton of money into the combustion engine to figure all that stuff out or do you just make everything at least a mild hybrid? Mazda has gone with the former, Volvo has gone with the latter.

BLUE TII

iTrader: (9)

Well, it is all relative.

Mazda is a tiny company that didn't dump a ton of money into combustion engine technology because they didn't have a ton of money to spend.

Still, like you say Mazda put almost EVERYTHING they had into refining the combustion engine technology.

Mazda doesn't pay their employees crap, they try to hire on people that are super motivated by the idea of getting something right instead of getting paid.

Mazda has always been its best when it was operating in this way... operating like a start-up.

I would call 1996-2008 when Ford had controlling share of Mazda stock "the dark years" (and Mazda still managed to produce the incredible RX-8 chassis and revive rotary engine production).

j9fd3s

iTrader: (3)

ive been thinking the rotary progression from 67 Cosmo to 787B (or FD), as almost like an art project. they had an idea, and in trying to capture it, they made many things we really like on the way to making a couple of iconic cars.

if you want the film parallel, its like Hitchcock's "wrong man" theme, which culminates in 'North by Northwest'.

and they have just started this Skyaktiv thing, and we'll see where they go with it

fmzambon

I don't think it's strictly one or the other. I mean, once Mazda decides it's time to go hybrid, the combustion engine part of the hybrid system will be using the HCCI technology they are developing now.

If Mazda spends X dollars (or yens) to develop a hybrid system, it will only benefit the hybrid vehicles, which will not be 100% of the lineup. If the same amount X is spent improving the combustion engine, then 100% of the vehicle lineup can benefit from that.

That is especially true if Mazda knows it can leverage off Toyota tech for the hybrid part, so why spend money redeveloping it?

arghx

iTrader: (3)

Only if they do with BMW did with Valvetronic and deploy it across the entire lineup which is a huge investment.

They don't have to develop a new hybrid system from scratch. Other manufacturers have done that and not had much success in terms of sales and fuel economy benefit. They can just buy stuff off the shelf. There are tons of suppliers out there who will sell you a kit basically.

Only if they deploy it to every engine. If it costs Mazda $500 or $1000 per engine (which is really expensive from the OEM side) it could be hard to justify putting that on lower priced vehicles if off the shelf hybrid systems are available. BMW made a huge commitment to Valvetronic and they only deployed it to all their engines maybe 15 years after Valvetronic first went to production.

I think the first Valvetronic engine was in 1999 and BMW went all Valvetronic/turbo in maybe 2013. Similarly Fiat/FCA has limited deployment of MultiAir because of the cost. There were rumors of a 3.6L V6 (Pentastar) with MultiAir, but it got canceled due to cost.

The other risk is the OBD risk. If they have problems with the OBD system California regulators will give huge huge fines.

It's a big problem the whole industry has with the very fast increasing greenhouse gas regulations. It's one of the reasons why diesels are projected to decrease in volume, and HCCI is about as complex as a modern diesel.

The main hybrid type that Toyota uses is the power-split architecture which isn't exactly the best for driving dynamics. It's good for appliances but doesn't fit so well with Mazda's "driving matters" philosophy. But maybe the more boring cars will get it, although I'd like to see a rotary range extender hybrid than a Prius knock off.

fmzambon

Another confirmation of the 2019 rotary range extender, directly by Kiyoshi Fujiwara

https://www.goauto.com.au/news/mazda...-04/65249.html

And then some more talk about the new Rx:

https://www.wheelsmag.com.au/news/17...lly-happening!

From the second link above:

Well, doesn't HCCI side step the flame propagation problem completely? If one can make HCCI work in a rotary, that is...

This 2020 date keeps popping up. There must be a reason for this

EDIT: another link: https://www.autoevolution.com/news/b...ar-120175.html

arghx

iTrader: (3)

"We cannot improve the rotary engine to the current conventional engine emissions"

That is a VERY vague statement. It doesn't say which emissions. It doesn't say under what conditions. And there's usually a work around, it just costs money.

For example, is it going too rich under heavy loads and failing tailpipe CO? Or is it still the engine out emission (HC primarily) during cold start on NEDC/WLTP or FTP test? Or is it newer stuff like N20 and Particulate Mass? Or does that just mean that the engine out emissions are worse than a piston engine, but with the right after treatment (such as catalytic converter and secondary air injection) it will pass tailpipe emissions?

Or is it purely a fuel economy/CO2/Greenhouse gas thing? That can be improved if you use it with some kind of electrification/mild hybrid like a 48 volt system.

The apex seal wear and oil consumption stuff has been in the works for years. I've already posted about the guy from MIT who was running the oil blowby study for them (oil leakage past gas and oil seals) and published 2 papers in collaboration with Mazda.

As for HCCI, it's probably not going to work on a cold start when tailpipe emissions are high due to the catalytic converter not being hot--whether it is a piston or a rotary engine.

j9fd3s

iTrader: (3)

the Nissan Cedric turns 67....

its Mazda's 100 year anniversary, AND the Tokyo Olympics....

fmzambon

Yeah, I know. I mean that it keeps popping up in relation to the rotary.

fmzambon

Ouch Mazda still working on rotary engine; needs more money

10 years? 20 years??? WTF
I hope it's just a bluff to come up with a surprise announcement soon

arghx

iTrader: (3)

while they have been underperforming profit wise, other reports are saying that they will release a rotary for a range extender similar to the concept.

So it may be true in the sense that an Rx-9 has been delayed, but that doesn't mean a rotary is dead.

RCCAZ 1

iTrader: (10)

Hoping their recent partnership with Toyota may help infuse some additonal R&D dollars. We'll see.