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CorneringArtist 10-02-2018 07:11 AM

Mazda to revive rotary engine as EV range extender
 
https://www.mazda-press.com/eu/news/...nge-extender-/

To be honest, if the resulting car is RWD, I'm sold even with the infrastructure needs for home charging.

Quote:

Mazda will launch its first Electric Vehicles (EV) in 2020 as part of its 'Sustainable Zoom-Zoom 2030' long-term technology development programme.



Unique technology approach

Mazda will initially launch two battery EVs. One powered solely by battery, the other pairing a battery with Mazda's small, lightweight and exceptionally quiet rotary engine as a range-extender.

The range-extender will recharge the battery when necessary to increase the vehicle's driving range, eliminating the range anxiety which continues to trouble a high percentage of battery EV users.

The rotary engine's small size and high power output make multiple electrification technology solutions possible via a shared packaging layout. Taking advantage of the rotary engine’s compatibility with gaseous fuels, the rotary-powered range extender is designed to also burn liquefied petroleum gas and provide a source of electricity in emergencies.



Mazda Sustainable Zoom-Zoom 2030

Expecting that internal combustion engines combined with some form of electrification will account for 95% of the vehicles it produces in 2030 (with battery electric vehicles accounting for the remaining 5%), Mazda will continue to focus on maximising the efficiency of the internal combustion engine, as exemplified by its new, new-generation SKYACTIV-X petrol engine, which combusts through compression ignition.

Mazda is committed to reducing its corporate average 'Well-to-Wheel' CO2 emissions to 50% of 2010 levels by 2030, and to 90% by 2050. But the company is also committed to the principal of the right solution at the right time and -since energy availability and automotive power source fitness vary from region to region- in the right place.

Clearly, the electric power generation system in any given region determines how much an EV can contribute to 'Well-to-Wheel' reductions in CO2 emissions. And with CO2-emitting thermal power generation still globally predominant, a goal to reduce those emissions is likely to diversify fuel options in the immediate future.

In addition to alternative fuels including compressed natural gas, liquefied petroleum gas and even hydrogen, the automotive industry is also researching the viability of recyclable liquid fuels such as biofuels from microalgae growth.

Mazda considers the development of the latter critical to achieving the carbon neutrality of cars powered by the internal combustion engine, and is already involved in joint research projects and studies with the Tokyo Institute of technology and Hiroshima University as part of an ongoing, industry-academia-government collaboration.

Mazda hopes to further the contributions of its 'Sustainable Zoom-Zoom 2030' vision to society by sending EVs with the range-extender to areas affected by natural disasters, providing LPG-generated electricity for those in need.

Ever committed to the pursuit of driving pleasure, Mazda will also be exploiting the advantages of electric drive in combination with the company's proprietary technologies to produce EVs that not only comply with ever tightening environmental restrictions, but also fulfil its ongoing commitment to Hashiru Yorokobi -the 'exhilaration of driving'- through its Jinba Ittai driver and car as one design and engineering philosophy.

Badhobz 10-02-2018 07:19 AM

makes no sense... if you wanted an IC engine for a range extender, why would you pick a gas guzzling rotary instead of your skyactive lineup which has amazing fuel efficiency. Yeah rotaries are cool, but not in this application.

BIC_BAWS 10-02-2018 07:25 AM

Quote:

Originally Posted by Badhobz (Post 8921691)
makes no sense... if you wanted an IC engine for a range extender, why would you pick a gas guzzling rotary instead of your skyactive lineup which has amazing fuel efficiency. Yeah rotaries are cool, but not in this application.

Because Mazda is focused on fuel efficiency, but wants to hit the rotary enthusiast market.

Ironically, it negates the purpose, like you said.

Sent from my Pixel XL using Tapatalk

CorneringArtist 10-02-2018 07:29 AM

Quote:

Originally Posted by Badhobz (Post 8921691)
makes no sense... if you wanted an IC engine for a range extender, why would you pick a gas guzzling rotary instead of your skyactive lineup which has amazing fuel efficiency. Yeah rotaries are cool, but not in this application.

Reading into it a little, a rotary at constant load is very efficient, which is why they're used in aircraft applications and in UAVs. When you use the rotary as the propulsion source itself in a car, that's when you have the inefficiency problems because of the varying loads from regular driving.

UnknownJinX 10-02-2018 09:19 AM

The idea has been around for a while, but I haven't seen any technical data yet, so I still have doubts.
Quote:

Originally Posted by Badhobz (Post 8921691)
makes no sense... if you wanted an IC engine for a range extender, why would you pick a gas guzzling rotary instead of your skyactive lineup which has amazing fuel efficiency. Yeah rotaries are cool, but not in this application.

There are advantages you are overlooking.

Ever looked at a 13B and wonder, "Wow, that tiny thing makes 200+ BHP?!" It actually works out to be about 1 cubic foot in physical volume. Now imagine a generator that will supposedly have about 1/4 of the displacement of the 13B. It can be very beneficial to packaging. People call it a "shoebox" for a reason.

And if you drive a rotary car, you will definitely notice the fact it's silky smooth, to the point that RX-7 and RX-8 both have a redline beeper from the factory. This is very beneficial for the comfort.

Fuel consumption is not a huge deal. Sure, a rotary is less efficient than a piston engine, but like CorneringArtist mentioned, it's running at a constant load as a generator only, which means it will still sip fuel rather than chug it like my RX-8.

Design the exhaust for that specific RPM the generator runs at and you will barely even notice it running.

The only real concern I have is how rotary burns oil by design. Burning 4-stroke is easier for maintenance but harder for emissions, while 2-stroke burns cleaner, but requires more attention.

CorneringArtist 10-02-2018 09:27 AM

They've already tested the rotary generator in the Mazda2 in 2013. It was a single rotor 300CC unit and reached about 400km combined range. Full electric was 200km. I'm guessing if they can minimise oil consumption or even have a feed system to maintain oil levels, it might solve that problem.

forcedot 10-02-2018 09:53 AM

Quote:

Originally Posted by UnknownJinX (Post 8921710)
The idea has been around for a while, but I haven't seen any technical data yet, so I still have doubts.There are advantages you are overlooking.

Ever looked at a 13B and wonder, "Wow, that tiny thing makes 200+ BHP?!" It actually works out to be about 1 cubic foot in physical volume. Now imagine a generator that will supposedly have about 1/4 of the displacement of the 13B. It can be very beneficial to packaging. People call it a "shoebox" for a reason.

And if you drive a rotary car, you will definitely notice the fact it's silky smooth, to the point that RX-7 and RX-8 both have a redline beeper from the factory. This is very beneficial for the comfort.

Fuel consumption is not a huge deal. Sure, a rotary is less efficient than a piston engine, but like CorneringArtist mentioned, it's running at a constant load as a generator only, which means it will still sip fuel rather than chug it like my RX-8.

Design the exhaust for that specific RPM the generator runs at and you will barely even notice it running.

The only real concern I have is how rotary burns oil by design. Burning 4-stroke is easier for maintenance but harder for emissions, while 2-stroke burns cleaner, but requires more attention.


I think you are down playing how inefficient these engines were.

An Evo for example made 70hp and 150 torque more (yes double the torque), was much heavier, had AWD, and yet was able to still be more fuel efficient than an RX8.

ANNND Evos were known to be one of the worst fuel guzzlers of the day when compared to any other car like a 135i that was able to produce even more power and use much less fuel.

I can't see a rotary ever making a return, especially with all the advancements in the piston engine. Even as just a range extender, its automatically a less efficient platform which defeats the whole purpose.

UnknownJinX 10-02-2018 10:20 AM

Quote:

Originally Posted by CorneringArtist (Post 8921712)
They've already tested the rotary generator in the Mazda2 in 2013. It was a single rotor 300CC unit and reached about 400km combined range. Full electric was 200km. I'm guessing if they can minimise oil consumption or even have a feed system to maintain oil levels, it might solve that problem.

I know they have tested it a long time ago, but it then just kind of disappeared. I could never find much technical data on it.


This actually makes me wonder if they will implement some designs from the 16X concept, namely the flatter rotor, direct injection, and all-aluminum construction(old 13Bs all come with aluminum housings and cast iron plates).

Quote:

Originally Posted by forcedot (Post 8921717)
I think you are down playing how inefficient these engines were.

An Evo for example made 70hp and 150 torque more (yes double the torque), was much heavier, had AWD, and yet was able to still be more fuel efficient than an RX8.

ANNND Evos were known to be one of the worst fuel guzzlers of the day when compared to any other car like a 135i that was able to produce even more power and use much less fuel.

I can't see a rotary ever making a return, especially with all the advancements in the piston engine. Even as just a range extender, its automatically a less efficient platform which defeats the whole purpose.

You can't compare an ICE-powered car and a range extender, as the load is constantly changing for an ICE-powered car. Pretty much every RX-7/RX-8 owner nowadays drives the piss out of them and rev them to redline every day. Of course the gas mileage will be crap because we are optimizing for smiles per gallon.

I realize that a rotary is not as efficient as a piston engine, I stated that, and Mazda realizes it as well. But what if you compare this new 300cc rotary range extender to a piston engine that can generate the same amount of power at a constant load? You just have a set RPM you can optimize everything(air flow, fuel injection, etc.) for and that can certainly have some interesting results.

One optimization I can think right off my head: I know that a stock RX-8 ECU will have the AFR in the range of 10 when you floor it, and in general, it runs pig rich to, ironically, help the catalytic converter. There is no need for that in a range extender. You can always just target close to the 14.7 stoich AFR and adjust a tiny bit for the NOx emission.

All that said, I am not delusional. There are definitely problems and that's why I am not overly optimistic about it. Last time I checked, Mazda only has about 20 people working on the rotary engine, so I am not that hopeful. The Renesis in RX-8 was already on the back bench when it was in development and look what happened. This will also give the marketing department a run for its money given rotary's track record of non-reliability.

welfare 10-02-2018 11:32 AM

man mazda dumped so much money and time into that rotary since buying the patent they just can't let it go lol.

but i still got love. got bit by the rotary bug myself once upon a time. took one look at the animated video and said this is just fucking retarded... i gotta get one! had an s4t2 and s5na street ported.
haven't looked much into this thing but i'm curious how it'll meet emissions standards. always a problem with rotaries since there's no dwell.
that and, as mentioned, the lubrication

Jmac 10-02-2018 12:17 PM

Quote:

Originally Posted by Badhobz (Post 8921691)
makes no sense... if you wanted an IC engine for a range extender, why would you pick a gas guzzling rotary instead of your skyactive lineup which has amazing fuel efficiency. Yeah rotaries are cool, but not in this application.

It says right in the article: small, lightweight, and quiet. Also, as mentioned, rotaries are decently efficient at constant loads.

UnknownJinX 10-02-2018 06:14 PM

Quote:

Originally Posted by welfare (Post 8921731)
man mazda dumped so much money and time into that rotary since buying the patent they just can't let it go lol.

but i still got love. got bit by the rotary bug myself once upon a time. took one look at the animated video and said this is just fucking retarded... i gotta get one! had an s4t2 and s5na street ported.
haven't looked much into this thing but i'm curious how it'll meet emissions standards. always a problem with rotaries since there's no dwell.
that and, as mentioned, the lubrication

They probably made it back by now with nearly 2 million rotary-powered cars sold since Cosmo Sport's debut in 1967 to RX-8's demise in 2012.

And yeah, I think all car people know it's a dumb idea in many ways, but everyone still loves it when they see one.

As for emission, I wonder if Mazda has figured out that sweet spot for the amount of oil to inject to keep the seals lubricated while keeping the emissions low. Again, it's a compromise between 4-stroke oil and 2-stroke oil. If they make the oil pan big enough and go with the same 4-stroke oil injection that has been used historically, the engine can potentially not need any oil added between oil changes. Actually, my RX-8's oil injection is electronically controlled and it doesn't consume much oil on highway trips(constant RPM and load).

It's true that the timing is static on a rotary engine. No valves in a rotary engine mean fewer moving parts and high revs, but the timing cannot be optimized for all RPM, unfortunately. However, since this generator runs at a set load and RPM, this will also become a non-issue. Figure out the best intake and exhaust port positions for that set RPM and you are good to go.

twitchyzero 10-02-2018 09:38 PM

few thoughts

I am continually blown away that a relatively small manufacturer can continue to push the envelope...Skyactiv-X squeezing out another 25% on top of the ultra-high compression the 2012 Skyactiv-G

this rotary-range extender in the article has already been tested since 2013

https://o.aolcdn.com/images/dims3/GL...e-extender.jpg

Quote:

the prototype range extender incorporates a 28 kW (38 PS; 38 hp) rotary engine generator, a lightweight 100 kg (220 lb) downsized single-rotor Wankel engine with 330 cc (20 cu in) displacement mounted on its side in the rear of the car. A 10 L (2.2 imp gal; 2.6 US gal) fuel tank that can be filled with gasoline, butane, or propane was claimed to almost double the EV range to 380 kilometres (236.1 mi).[53]
and sorry but even a late-model RX-8 mpg is 18 accordingly to Fuelly and EPA hence not bouncing off the rev-limiter...which is basically half of Skyactiv-G's efficiency as the sole powerplant

Also, do you still need to warm up a Rotary for longevity sake?

the hassle and durability of a rotary probably means I would not want one in a daily

welfare 10-02-2018 10:16 PM

Quote:

Originally Posted by UnknownJinX (Post 8921768)

As for emission, I wonder if Mazda has figured out that sweet spot for the amount of oil to inject to keep the seals lubricated while keeping the emissions low. Again, it's a compromise between 4-stroke oil and 2-stroke oil. If they make the oil pan big enough and go with the same 4-stroke oil injection that has been used historically, the engine can potentially not need any oil added between oil changes. Actually, my RX-8's oil injection is electronically controlled and it doesn't consume much oil on highway trips(constant RPM and load).

It's true that the timing is static on a rotary engine. No valves in a rotary engine mean fewer moving parts and high revs, but the timing cannot be optimized for all RPM, unfortunately. However, since this generator runs at a set load and RPM, this will also become a non-issue. Figure out the best intake and exhaust port positions for that set RPM and you are good to go.


actually when i said dwell i was referring to piston dwell time. Which promotes a fuller burn and higher thermal efficiency.
There's no dwell in a rotary since the rotor is constantly spinning. During combustion, the charge mixture at the trailing side of the rotor is pretty much thrown out the tailpipe.
Hence the trailing plug. But it doesn't help much.
One of the reasons for the multiple cats and high hc.

Maybe they'll implement hcci. That would probably remedy it. Or maybe laser ignition.

underscore 10-15-2018 03:09 PM

Quote:

Originally Posted by UnknownJinX (Post 8921768)
As for emission, I wonder if Mazda has figured out that sweet spot for the amount of oil to inject to keep the seals lubricated while keeping the emissions low.

I would think that since the load/rpm can be fixed they can design the motor for maximum efficiency/longevity under those conditions. So instead of needing seals and oiling designed for a wide range of operating conditions and abuse levels they can dial it back to seals that will work well for what the generator will be running at and only need to provide enough oil to support that.

UnknownJinX 10-15-2018 06:39 PM

1 Attachment(s)
Quote:

Originally Posted by twitchyzero (Post 8921809)
few thoughts

I am continually blown away that a relatively small manufacturer can continue to push the envelope...Skyactiv-X squeezing out another 25% on top of the ultra-high compression the 2012 Skyactiv-G

this rotary-range extender in the article has already been tested since 2013

https://o.aolcdn.com/images/dims3/GL...e-extender.jpg

and sorry but even a late-model RX-8 mpg is 18 accordingly to Fuelly and EPA hence not bouncing off the rev-limiter...which is basically half of Skyactiv-G's efficiency as the sole powerplant

Also, do you still need to warm up a Rotary for longevity sake?

the hassle and durability of a rotary probably means I would not want one in a daily

Mazda has always been known to pursue quirky engine technologies.

And yes, RX-8 gas mileage is pretty bad, but again, as it has to drive the wheels, the load will constantly change as you accelerate the car. The highway mileage also suffers because of the short gears and thus more pumping losses. My RX-8 will rev at 3k RPM at 92 km/h in 6th(last) gear. It's to the point that some RX-7 owners claim that they get better gas mileage on highways. Also, remember that these are sports cars - performance will be a bigger concern than fuel economy.

As for warm-up, that has always been a myth in ANY modern car. The "idle until warm" should have died with carburetors. The only time I would do that is if my windshield is covered in ice and I can't safely drive until everything is warmed up. Otherwise, I idle for 15 seconds after a cold start and off I go. Any engine shouldn't be driven hard when cold, piston or rotary.

And one last thing to clear up since we are here: flooding. I have never flooded my 8. I stalled my car while cold twice, and both times it fired right back up. If an RX-8 floods, something is wrong. Either your ignition systems are dying, your battery is taking a dump or your engine has low compression.

Quote:

Originally Posted by welfare (Post 8921811)
actually when i said dwell i was referring to piston dwell time. Which promotes a fuller burn and higher thermal efficiency.
There's no dwell in a rotary since the rotor is constantly spinning. During combustion, the charge mixture at the trailing side of the rotor is pretty much thrown out the tailpipe.
Hence the trailing plug. But it doesn't help much.
One of the reasons for the multiple cats and high hc.

Maybe they'll implement hcci. That would probably remedy it. Or maybe laser ignition.

One key difference between the RX-7 and RX-8 engines is the fact that the RX-8 uses side exhaust port vs. RX-7's peripheral exhaust port.

The RX-8 side exhaust port gets rid of the port overlapping and makes it so that there is a greater chance that some unburnt gas will be burned in the next cycle.

I think Mazda will be sticking to the side exhaust ports.

HCCI could be a solution, but wouldn't that require a higher compression ratio? A Wankel rotary engine is only capable of 11:1 or so by design. That's why Rolls Royce's concept diesel Wankel had two rotors - a big rotor as a compressor and a small rotor as the actual engine.

As for laser... Just the cost alone will mean it won't be in an econo car. And is it even in use in any road vehicles, anyway?

Quote:

Originally Posted by underscore (Post 8923590)
I would think that since the load/rpm can be fixed they can design the motor for maximum efficiency/longevity under those conditions. So instead of needing seals and oiling designed for a wide range of operating conditions and abuse levels they can dial it back to seals that will work well for what the generator will be running at and only need to provide enough oil to support that.


True, and in an RX-8 that's driven genetally, it wouldn't burn much oil. Again, the constant load and RPM means they can optimize everything for that particular condition.


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