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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

#11

Post by ianai »

_ea1k wrote: post #7
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…

Low end torque tends to be the rotary's Achilles heel. I think the claim being made is that efficiency is better at high, steady RPMs, but tbh, I've always found that claim a bit dubious. If you love the rotary engine, this does have some nice perks as the electric motor basically fixes the rotary engine's main weakness. Having said that, I'd have been much more excited about this 10-15 years ago.

A YTer said it allows the rotary engine to operate in its best circumstances. It’s essentially a range extender while battery tech improves.

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

#15

Post by mattmaroon »

I have never understood why the Volt Series Hybrid idea never took off. It is more efficient to turn gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels. Is it perhaps that the cost involved is just too much more than a plugin hybrid to make the small extra fuel savings worth it?

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

#16

Post by sethhochberg »

jpgvm wrote: post #3
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 can be made extremely compact so that might have something to do with it, i.e it has both very high power to weight and power to volume specs. I honestly don't know if that is the reason though, perhaps someone more knowledgeable of the specifics of range extenders might chime in but I imagine that is an important factor.

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 remember discussion here a handful of months ago about a startup marketing a similar EV range extender engine design.

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

#17

Post by speed_spread »

jpgvm wrote: post #3
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 can be made extremely compact so that might have something to do with it, i.e it has both very high power to weight and power to volume specs. I honestly don't know if that is the reason though, perhaps someone more knowledgeable of the specifics of range extenders might chime in but I imagine that is an important factor.

In a hybrid vehicle, the gas engine can be run mostly as a generator, which makes it possible to further optimize it for a very specific load. It's possible that such an updated+tuned Wankel could be a great fit for certain applications where space and weight are at a premium.

They can simulate lots of it but to get real answers, they have to build the engine and see how it holds up.

Also Mazda is a small-ish manufacturer at the Japanese scale. Since Wankels are part of their identity they could decide to build a car with it even though the downsides wouldn't make sense for a "rational" brand like Toyota. It can give them that creative freedom that help make desirable cars and keep Mazda relevant.

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

#18

Post by jiveturkey »

pengaru wrote: post #5
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…

> Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? What does low end torque have to do with electrical generation ?

It's not a direct connection.

You do want efficient horsepower to drive a generator. More low end torque means the HP comes at lower RPM, which should mean less fuel consumption.

Sibling says the achilles heel of the Wankel rotary is low end torque, but you don't take the direct output from the engine, it goes through gear reduction for final drive output. The real achilles heel is the awful emissions. It's more or less a 2 cycle engine from that POV.

When driven at variable speeds it's hard to wrangle.

The reason it's well suited for electrical generation is its mechanical simplicity, compactness, low weight, low NVH, and not least important, "rotary" brand value. I suppose that when run at constant RPM and constant or smoothly changing load, the emissions is easier to deal with.

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

#19

Post by HPsquared »

mattmaroon wrote: post #15

I have never understood why the Volt Series Hybrid idea never took off. It is more efficient to turn gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels. Is it perhaps that the cost involved is just too much more than a plugin hybrid to make the small extra fuel savings worth it?

Surely the "generator -> charger -> battery -> inverter -> motor" chain is less efficient than a driveshaft. Perhaps the only benefit is the engine can run at an optimal speed, but an appropriate gear ratio should handle that.

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

#20

Post by ch_sm »

mattmaroon wrote: post #15

I have never understood why the Volt Series Hybrid idea never took off. It is more efficient to turn gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels. Is it perhaps that the cost involved is just too much more than a plugin hybrid to make the small extra fuel savings worth it?

> It is more efficient to turn gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels

I thought so too, but my research suggested that the efficiency is pretty much the same if not worse and power delivery is worse. Do you have some links? I‘d like to be wrong on this one.

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