Those cleverJapanese.....

[Keith Lane]

Auto engineers, that is.

They have learned how to restart the engine after a shutdown at a stop light/sign, which according to them improves fuel economy by 10% (the stopping that is).

http://www.mazda.com/publicity/release/2008/200809/080909a.html

In order to restart the engine by combustion, the pistons must be stopped at exactly the correct position to create the right balance of air volume in each cylinder. The Smart Idle Stop System provides precise control over the piston positions during engine shutdown to accomplish this. The SISS indexes each cylinder and initiates fuel injection before the engine begins to rotate. This enables the engine to be restarted in just 0.35 seconds*2, roughly half the time of a conventional electric motor idling stop system.

 

[woodstock]

BMW is already doing that... or something along those lines. The guy from BMW who drove us to the airport had a car that did that.

 

[jesse]

I think Toyota has been doing that in their Prius since day one.

 

[Keith Lane]

I'm pretty sure Mazda is the only one restarting the engine without the aid of the electric starter used to start the engine normally. They are indexing the engine and pre-fueling the cylinder that is just past TDC on the compression stroke and when they want to restart the engine, just fire that spark plug, using the power stroke to restart. I have two relatives running the Toyota and I always hear the starter motor kick the engine back to life.

Of course,I have been wrong more than twice or three times a day for a while now.

 

[Capt. Geoffrey Thorpe]

I think Toyota has been doing that in their Prius since day one.

They are using the electric motor as the starter - that's been around for quite a while. What Mazda is doing different is directly injecting fuel into a cylinder and firing the spark plug to start the engine WITHOUT using a starter.

 

[jesse]

They are using the electric motor as the starter - that's been around for quite a while. What Mazda is doing different is directly injecting fuel into a cylinder and firing the spark plug to start the engine WITHOUT using a starter.

Looks like you might be right. I know someone that owns an older Prius and just bought a new one. He told me it starts in the way that this Mazda article describes. He probably just has no idea what he actually owns and read that same article and thought that was his car.

 

[Steve Foley]

Auto engineers, that is.

They have learned how to restart the engine after a shutdown at a stop light/sign, which according to them improves fuel economy by 10% (the stopping that is).

I've got a 1987 Jeep Wrangler that does that. Every time I stop (red light, stop sign, traffic) it shuts off. I start it again by turning the key. What's the big deal?

 

[SCCutler]

Like a big EZ-Go golf cart. Big deal.

Makes some sense in heavily urban areas, provided (of course) it is not hot enough to need AC.

Many Japanese "innovations" are adaptations more suited to their home market than most of ours; this is one such example.

The complexity of a system which must index a cylinder to the proper restart position each time it automatically shuts down is a lot better suited to Japanese market and driving conditions, including: (1) the extreme vehicle density in Japanese cities, creating conditions where this technology can actually help, and (2) Japanese vehicle laws, which essentially mandate replacement of vehicles before they get old.

Their drawing seems to imply that the alternator is used as a motor to assist in indexing the restart cylinder.