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Mazda’s rotary engine in the age of the electric car

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Re: Mazda’s rotary engine in the age of the electric car

#151

Post by simne »

486sx33 wrote: post #2

Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? Is it more efficient with less load? The article mostly makes it sound like Mazda just loves the wankle and wants to find any possibly way to bring it back - even though it has “high” emissions… so coupling it with a hybrid electric motor makes it happen.. That can’t be t…

Wankels have only one advantage - they are about two times more powerful on same volume (you could consider them as very clean two stroke engines).

Unfortunately, Wankels have extremely huge mechanical problems - complex geometry (classic ICU are very close to just cylinders), need of better materials, depend on much better oil.

And also big problem is production scale, as I talked with people, they considered Wankels as toy, you will just utilize when it run out guarantee term.

For example, for standard ICU, considered big repair, sleeves, so they will continue working, sure, less heavy duty than new.

Re: Mazda’s rotary engine in the age of the electric car

#152

Post by KptMarchewa »

cpursley wrote: post #134
pavlov wrote: post #131

Earlier quoted context omitted.

It can be the whole story. Engineering organizations fall in love with superficial attributes of solutions that worked especially well for them in the past. When RIM/BlackBerry realized the iPhone was a serious threat, they built a touchscreen phone where the entire display produces a physical clicking effect because they were so convinced that what people really want from a smartphone is the click of a keyboard. Maz…

> Mazda is BlackBerry No, they're not. Go test drive a Miata. They make the most fun cars to come out of Japan. And also have one of the better design languages.

As much as I love Mazda, if the only thing they'll have for them is fun, they are dead as a mass manufacturer.

Re: Mazda’s rotary engine in the age of the electric car

#154

Post by simne »

coryrc wrote: post #28
sethhochberg wrote: post #16

Earlier quoted context omitted.

They have a pretty narrow power band (produce efficient max power at a small range of RPMs) which always somewhat limited their use for normal ICE cars, but is a pretty workable constraint for an electrical generator. So you have compact size, good power to weight ratio, and power limitations that don't really matter for range extender purposes. Lots of potential. I can't find the article right now, but I'd swear I r…

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

Gas turbines are economically effective when larger than about 300hp. This border with time slow lowered, but I don't know, when it will appear somewhere about 50Kw of most popular automobiles (Toyota Corolla, WV Golf, Ford Focus).

When scaling down, gas turbines become much more expensive than ICE. For example on small planes market, exist many dual-powered models (in range 200-300hp), and with gas turbine it typically priced twice of ICU-powered with very similar parameters. Range of 1000hp+ on planes are near totally gas turbines.

Re: Mazda’s rotary engine in the age of the electric car

#155

Post by ggreer »

discreteevent wrote: post #120
ggreer wrote: post #60

Earlier quoted context omitted.

Several reasons. First, like most of the Japanese manufacturers, Mazda bet against electric vehicles. They focused R&D on improving engine efficiency and getting their engines to run on hydrogen. If Mazda wants to make electric vehicles now, they have to play catch-up, or license key technologies from other manufacturers. Second, batteries are heavy. For sedans and mid-size crossovers, this isn't much of a problem. E…

“Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere.” - Colin Chapman (Lotus)

I agree with the adage, but brute force seems to win in this specific case. Even though it's the lightest model made, my Miata only gets 0.82g on the skidpad.[1] The Model 3 Performance gets 0.96g thanks to its wide tires, which are needed to transfer all its power to the asphalt.[2] This difference isn't just due to the 1990 Miata's older suspension and tire technology. Even the latest Miatas only get 0.90g of lateral acceleration.[3]

1. https://www.caranddriver.com/reviews/a15141519/1990-mazda-mx...

2. https://www.caranddriver.com/reviews/a36329678/2019-tesla-mo...

3. https://www.caranddriver.com/reviews/a22678665/2019-mazda-mx...

Re: Mazda’s rotary engine in the age of the electric car

#156

Post by DarmokJalad1701 »

Baeocystin wrote: post #137
avalys wrote: post #100

Earlier quoted context omitted.

What's your point? There's no reason to have a generator that charges the pack in a hurry. It really only needs to cover the maximum sustained average draw - driving up an extended grade at high speed. That's a lot less than 300 hp - it's probably not more than 80 hp or so at most.

I remember back in the 90's in auto shop we calculated that you'd only need 15-25hp continuous to essentially power all of a car's needs if you could smooth demand for power from the peaks over the length of the trip. It stuck with me as a surprisingly small number, but it mathed out, even including heating and AC. Cars are both larger and more aerodynamic nowadays; I wonder if the amount would still be the same?

A Model 3 or Model Y's "rated efficiency" of 250-300 Wh/mi corresponds to 16-20 kW assuming a 65 mph speed. That's well within that range you quote.

Re: Mazda’s rotary engine in the age of the electric car

#157

Post by defrost »

avalys wrote: post #100
bob1029 wrote: post #83

Earlier quoted context omitted.

300 HP = ~220 kW I believe a Tesla can charge its battery pack at approximately this rate.

What's your point? There's no reason to have a generator that charges the pack in a hurry. It really only needs to cover the maximum sustained average draw - driving up an extended grade at high speed. That's a lot less than 300 hp - it's probably not more than 80 hp or so at most.

For many 'standard' driving patterns (relatively 'flat' urban commutes with approx balanced medium length up and down grades) there are lightweight optimal solutions for EV's that can minimise both battery pack size (and weight) and the need to draw on a small rotary engine for recharge.

The UK's drone engines come in light and small with models that range from 5 BHP to 120 BHP with 40 BHP being suitable for broad swathe of "typical" driving.

https://www.aieuk.com/wankel-rotary-uav-engines/

Re: Mazda’s rotary engine in the age of the electric car

#158

Post by sanderjd »

ryukoposting wrote: post #141
486sx33 wrote: post #2

Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? Is it more efficient with less load? The article mostly makes it sound like Mazda just loves the wankle and wants to find any possibly way to bring it back - even though it has “high” emissions… so coupling it with a hybrid electric motor makes it happen.. That can’t be t…

It has nothing to do with sentimentality. Wankels have tremendous power-to-weight and power-to-size ratios. Their main problem is reliability. The generally accepted solution to improve rotary engine reliability (oil injection) results in poor emissions. The wide, flat-ish combustion chamber doesn't help the emissions problem, either. The Wankel is at its most efficient and its most reliable when operating at a const…

These three paragraphs would have been a far more enlightening article than the posted article.

Re: Mazda’s rotary engine in the age of the electric car

#159

Post by ghostly_s »

ryukoposting wrote: post #141
486sx33 wrote: post #2

Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? Is it more efficient with less load? The article mostly makes it sound like Mazda just loves the wankle and wants to find any possibly way to bring it back - even though it has “high” emissions… so coupling it with a hybrid electric motor makes it happen.. That can’t be t…

It has nothing to do with sentimentality. Wankels have tremendous power-to-weight and power-to-size ratios. Their main problem is reliability. The generally accepted solution to improve rotary engine reliability (oil injection) results in poor emissions. The wide, flat-ish combustion chamber doesn't help the emissions problem, either. The Wankel is at its most efficient and its most reliable when operating at a const…

> The Wankel is at its most efficient and its most reliable when operating at a constant RPM. Conveniently, the EV generator application demands a pretty flat RPM band.

If I understand the article correctly, the "series" hybrid configuration means precisely that it cannot operate at the ideal rpm when charging the battery, because it is always driving the wheels directly as well.

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