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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

#131

Post by pavlov »

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 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.

Mazda is BlackBerry, and the rotary engine is their clicky keyboard.

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

#132

Post by cranky908canuck »

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.

Want to comment explicitly, though I upvoted a similar comment ... a gas turbine in a consumer car will be a maintainability nightmare (where do you find the technicians that can do anything with it?), at least in the current automotive ecosystem.

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

#133

Post by pfdietz »

gambiting wrote: post #123
01HNNWZ0MV43FF wrote: post #103

Earlier quoted context omitted.

This company Toyota started a pretty popular line of hybrid gas-electric cars, maybe 20 years ago, called Priuses. I think they sell pretty well. I see a lot of them running as taxis. The new ones can plug in and drive a few miles on the highway on pure electric before starting the gas engine.

Priuses do use the ICE to drive the wheels though, no?

Yes, they are parallel hybrids.

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

#134

Post by cpursley »

pavlov wrote: post #131
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 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.

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

#135

Post by fragmede »

explorigin wrote: post #69
Projectiboga wrote: post #13

I was always impressed by this engine in my childhood, but it never really caught on. Here is a variation I've seen on the internet, i'm not sure how practible it would be. https://arstechnica.com/cars/2023/11/this-inside-out-design-...

https://www.youtube.com/watch?v=X5UOqZn43gY It has longevity-issues due to an internal roller bearing on the main shaft.

Depending on how it's being used. Rotary engines are better in some ways when being run hard (ie as a track car) compared to more traditional layouts.

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

#136

Post by thehappypm »

joking wrote: post #10
WillAdams wrote: post #6

Earlier quoted context omitted.

Pretty much. One (potential?) advantage not mentioned in the article is lighter weight relative to a similar traditional engine.

Would be good as a range extender motor. I think smaller battery cars with range extenders should be a better option than what we have now.

Oh my God, if Tesla sold a range extender gas generator that sat in the frunk, and could add an extra 150 miles.. take my money.

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

#137

Post by Baeocystin »

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.

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?

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

#138

Post by labcomputer »

dragontamer wrote: post #29
HPsquared wrote: post #19

Earlier quoted context omitted.

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.

> but an appropriate gear ratio should handle that. See Prius's "Powersplit Device". I'd describe the Powersplit device to be a combination of generator/alternator, starter/electric motor, reversed-differential (2x power inputs -> 1x driveshaft), and effective gear-ratio. All in one planetary gearset. EV motor2 determines the speed of the car. The ICE motor can spin at any speed that the computer determines to be use…

> I do think that the Prius (and Prius Prime) have surpassed the Volt's design, and the proof is in the pudding. Prius Prime has 52mpg, a figure far more efficient than the Volt ever had.

This is partly because the Prius is optimized as a hybrid-first design, while the Volt is optimized as a BEV-first design. The difference is in the gear ratios of the planetary CVTs: Prius is optimized to minimize the amount of energy transmitted electrically, which maximizes overall efficiency.

However, that design is sub-optimal for a car that you want to act like an EV. As your link shows, the Prius must have the ICE spinning at speeds greater than 42 mph. Not a problem for a hybrid, but that doesn't work for a "range-extender EV" like the Volt. Additionally, (before the current model year) Toyota's plug-in hybrids can't provide full acceleration in EV mode--they always kick in the ICE when you floor it. That's again a consequence of how the transmission is optimized for hybrid operation.

By making compromises to the gasoline efficiency, GM was able to create a car which acts like a real EV most of the time: A 1st gen Volt will go at least 80 mph in EV mode, and won't turn on the ICE (come hell or high water) until the battery is below 5%. And, it will do that for an honest 35 miles of freeway driving.

The second generation Volt uses GM's "2 mode" hybrid transmission, which closes some of the MPG gap by adding one fixed ratio (100% mechanical transmission) as well as high and low speed eCVT ratios (to minimize electrical power in those two speed ranges).

https://www.gm-volt.com/threads/gen-2-volt-transmission-oper...

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

#139

Post by fragmede »

ggreer wrote: post #112
eggsboenk wrote: post #106

Earlier quoted context omitted.

The McMurtry Spéirling is claimed to be under 1000kg. A lightweight electric car may not be an oxymoron after all. Just some concessions to make.

The McMurtry Spéirling is not street legal and it costs $1 million.

And what a car it is!

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

#140

Post by SeanLuke »

> Despite all this, though, the MX-30 R-EV still falls somewhat short, with a catalog fuel efficiency of 15.4 kilometers per liter (as measured in WLTC mode). With no similar vehicles on the market, like-for-like comparison is not possible, although the Toyota RAV4 plug-in hybrid gets 22.2 km/l, while the Prius plug-in hybrid gets 26.0 km/l. The MX-30 R-EV is clearly inferior in terms of its fuel economy.

That's because the engine serves an entirely different purpose. The Prius plug-in hybrid is a 13.6kWh battery mated to a regular engine. The MX-30 R-EV is a 17.8 kWh battery mated to a tiny ultralight emergency range extender.

As to similar designed cars, um, hello, the BMW I3 Hybrid? Exactly the same design.

The failing of the MX-30 R-EV is that its battery size is pathetically small for what amounts to an EV with a range extender. It is an embarrassment.

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