Paris Preview: Mazda introducing new, smarter Smart Idle Stop System
Automatic start-stop systems for engines are becoming increasingly common on vehicles in Europe. However, these systems typically use the conventional starter motor to re-start the engines after a stop. This can result in slow re-starts and additional load on the starter. Mazda has devised a new system that they claim will provide quicker, more consistent re-starts. The Mazda system relies on direct injection to function. When the engine is stopped, sensors are used to stop the engine with the pistons in a precise location. This will allow one of the cylinders to have a known amount of air in the combustion chamber. When the time comes to re-start, fuel is injected directly into the cylinder and ignited. The expansion of the burning fuel is used to get the engine turning to re-start the engine. Mazda claims the engine can re-start in 350 milliseconds, about half the time of a conventional starter. The re-starts are indexed to consecutive cylinders so that the same cylinder isn't used every time. Mazda claims a 10 percent reduction in fuel consumption on the Japanese urban test cycle.
[Source: Mazda]
Mazda Develops UNIQUE Smart Idle Stop System Using Direct Injection Engine Technology
HIROSHIMA, Japan-Mazda Motor Corporation has independently developed an idling stop system, called the Smart Idle Stop System (SISS), which improves fuel economy by about ten percent (in Japan's 10-15 mode tests*1) in urban areas where vehicles frequently stop at traffic lights or in heavy traffic during operation. The SISS uses direct injection technology to achieve an excellent engine restart, ensuring drivers do not experience any discomfort with the new system. Mazda plans to introduce this core environmental technology to the marketplace in 2009.
Idling stop systems save fuel by shutting down the engine automatically when the car is stationary, and restarts it when the driver resumes driving.
Conventional idling stop systems restart a vehicle's engine with an electric motor using exactly the same process as when the engine is started normally. Mazda's SISS, on the other hand, restarts the engine through combustion. Mazda's system initiates engine restart by injecting fuel directly into the cylinder while the engine is stopped, and igniting it to generate downward piston force.
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.
In addition to saving fuel, Mazda's Smart Idle Stop System ensures that the engine will restart quickly and with exactly the same timing every time. Drivers will feel no delay when resuming their drive, which means they can enjoy a comfortable and stress-free ride.
| *1 | The 10-15 mode test is the Japanese standard for emission certification and fuel economy for light duty vehicles. It consists of two separate drive cycles. The 10-mode drive cycle is a low speed drive cycle test, while the 15-mode is a higher speed assessment. |
| *2 | For vehicles with automatic transmissions. Restart times measured by Mazda. |
Reader Comments (Page 1 of 1)
Tim 11:31AM (9/10/2008)
Brilliant!
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ryan 8:32AM (9/10/2008)
Give me this system with a manual transmission and a small displacement turbo diesel packed into the Demio and you have my money.
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woodenbee 9:10AM (9/10/2008)
It's a shame 99% of Americans think that restarting your engine uses more gas than restarting! that's why they sit there idling all day, gee I wonder who fed us that lie? why is it most of my questions have the same answer? big oil
or new term "military, petroleum, automotive industrial complex"
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Jerry 9:23AM (9/10/2008)
Can this remove the need and weight of a starter and allow the battery to be smaller and lighter?
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Bill 11:13AM (9/10/2008)
I doubt this could work for cold starts, so you'd still need a starter.
Just my impression, I'm certainly not an engineer.
GoodCheer 9:47AM (9/10/2008)
Wow, that's smart! I love it.
Even on ABG it's not every day that I see a new idea or application that makes me really want to shake the engineer's hand. Simple, efficient, and inexpensive to implement (once you have direct injection)... what a great idea!
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Mike Z 9:49AM (9/10/2008)
"It's a shame 99% of Americans think that restarting your engine uses more gas than restarting!"
Source?
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Whopper 11:11AM (9/10/2008)
Well, shades of the Coffman starter! To the uninitiated, this was the method of starting some radial aircraft engines in the 1930' & 40's. You load a blank shotgun cartridge into the breach, pump the primer to inject some fuel into the cylinder and fire the cartridge. The fuel burns, hopefully cranking the engine sufficiently to start it.
@ryan, the diesel, being a compression ignition device, would have to have an auxiliary ignition system since there is no compression with the piston stationary.
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Woodenbee 11:55AM (9/10/2008)
Mike Z, well its just an observation, 80% don't care enough to know either way, the other 19% are deliberately misled, and the remaining 1% read books and stuff, plus I see people doing it all the time, especially in diesels, whats wrong with these people! turn off your engine when your not driving! no matter whose paying for the gas/diesel.
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jzj 12:18PM (9/10/2008)
I'm not aware of a means of stopping an engine in a particular crank position: how is that accomplished?
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Chris 12:40PM (9/10/2008)
Other manufacturers with hybrids have been using similar engine pre-orientation to reduce NVH (Noise,Vibration, and Harshness) on restart. It makes sense to use the electric motor (or alternator in the BAS types) to position at least one cylinder for easy combustion on the next start-up.
Direct injection just allows this to go one step further by having the cylinder already compressed (and past TDC), then spray fuel and ignite. I expect they save the time it takes for 1 revolution (intake and compression) over a non-direct injected engine and you don't need to turn the engine via some type of starter/motor at startup.
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