"will Ultracapacitors Save Start-stop Systems From Consumer Wrath?"

[champsman]

http://www.mazda.com/technology/env/i-stop/

From what I see, and think , it has to stop a touch past TDC, or fireing backwards might be possable

 

[Ty]

Not sure what the point would be of spinning backward first instead of just continuing in the usual direction. One cylinder firing is the same as any other firing. And at TDC it should already HAVE a fuel charge and compression. I always was told it was BAD to spin a motor backward, though I guess I can't exactly say why now that you mention it. Anyway, I really wonder how they get the engine to stop right at the point of rotation they want it at?

I wondered the same thing. The way they did it, they didn't ha e to add in the cost of regenerative braking or battery or alternator. I think

Not sure what the point would be of spinning backward first instead of just continuing in the usual direction. One cylinder firing is the same as any other firing. And at TDC it should already HAVE a fuel charge and compression. I always was told it was BAD to spin a motor backward, though I guess I can't exactly say why now that you mention it. Anyway, I really wonder how they get the engine to stop right at the point of rotation they want it at?

http://m.caranddriver.com/features/engine-stop-start-systems-explained-tech-dept

Mazda tried to complicate things in 2008 when it teased engine geeks with its theoretical Smart Idle Stop System (SISS), which attempted the operation without relying on the starter motor. SISS would have manipulated the alternator load to stop all four pistons exactly halfway through their stroke. To restart, the cylinder in its compression stroke would get a small squirt of fuel that, when burned, would spin the internals backward just enough to produce compression in the neighboring cylinder. That cylinder would then receive a normal supply of fuel, and its combustion would spin the crank in the proper direction. Unfortunately, this elegant idea never materialized, and Mazda went the more traditional route with its i-stop, available on 2.0-liter gasoline Mazdas in Japan and Europe. The i-stop system, though, does use an initial combustion blast to aid firing, easing starter stress and reducing the restart time by half, to a claimed 0.35 second.


I stand corrected. I read it in Car and Driver. I didn't realize they never used the system in production. Still, they fire that first cylinder first which reduces wear and tear on the starter and battery.

 

[Ty]

Interesting system. As I understand it though it would only work on a gasoline direct injected engine. Looks like it still uses the starter motor also. Seems to be all about making the startup faster and less noticeable. The Elio motor isn't direct injected is it?

No, the Elio is not direct injection... the first year model anyway.
With how small the engine is, it won't take much of starter to spin it over without fancy stuff.

 

[carzes]

No, the Elio is not direct injection... the first year model anyway.
With how small the engine is, it won't take much of starter to spin it over without fancy stuff.

Agreed. Then again, any way I've done the math there is no point putting a start/stop system on a car that I figure can idle for 14 hours on a gallon of gasoline unless the system cost pretty much nothing. Most people don't like them anyway.

 

[goofyone]

Mazda is actually already using capacitors in their i-ELOOP brake energy regeneration system which is designed to work in tandem with the i-Stop system to allow the engine to stay off longer by providing power for the accessories.

"In 2011, Mazda announced i-ELOOP, a system which uses a variable-voltage alternator to convert kinetic energy to electric power during deceleration. The energy stored in a double-layer capacitor, is used to supply power needed by vehicle electrical systems. When used in conjunction with Mazda’s start-stop system, i-Stop, the company claims fuel savings of up to 10%."
http://en.wikipedia.org/wiki/Start-stop_system#Mazda

http://www.motorauthority.com/news/...king-system-switches-batteries-for-capacitors
http://www.mazda.com/technology/env/i-eloop/