Talk:Gasoline direct injection

Honda 2.0 L DOHC i-VTEC I

Here's the transcript of the technology video from http://world.honda.com/HDTV/news/2003-4031127a/ (10 min 19 Mbyte streamed Flash Video, resides in your browser cache once downloaded).

HONDA: The Power of Dreams

HONDA cars must be both fun to drive and environment-friendly. That's why we've developed a direct injection gasoline engine with an air-fuel ratio of 65 to 1. This is an unheard of level of ultra-lean combustion. The new engine delivers superior fuel economy and emission levels, along with high output and abundant torque. Introducing the new HONDA 2-liter DOHC i-VTEC I direct injection engine!

In direct injection engines, the fuel is injected directly into the cylinder. This allows leaner combustion for greater fuel economy. However, conventional direct injection technology has failed to deliver both clean exhaust emissions during lean-burning and high output during combustion at stoichiometric air-fuel ratios. That's why HONDA turned its attention to developing direct injection technology that would excel in both respects, using the i-VTEC engine as a base.

In addition to HONDA's i-VTEC intelligent valve timing and lift function, the i-VTEC I also features a newly-developed center injection system, a HONDA original. With other systems, the injector is positioned at an angle, but with the center injection system, it is positioned vertically, injecting the fuel at right angles to the piston, so that the fuel will not adhere to the cylinder wall. And since the fuel is injected directly into the cavity on the piston's upper surface, regardless of the piston position, injection timing and volume can be freely adjusted to obtain ultra-lean burn operation over a broader range. The injection system uses 10 mega-pascal injection pressure and a lateral swirl guide on the injector tip to achieve a droplet size just one tenth that of most engines. What's more, the optimised injection pattern disperses the fuel conically, to achieve improved combustion efficiency. The new engine employs these core technologies to achieve optimal combustion control in all driving conditions; together with advanced nitrogen oxide reduction technology, they insure that i-VTEC I delivers high fuel economy, clean emissions, powerful output and ample torque, outstanding engine performance.

The i-VTEC I offers outstanding fuel economy during both ultra-lean and stoichiometric combustion. Under ordinary driving conditions, when engine load is comparatively low, the engine uses ultra-lean combustion. With the i-VTEC system, the V-TEC mechanism causes one of the intake valves to remain closed, generating a powerful swirl pattern. Meanwhile, VTC optimises valve overlap timing, to create a stable environment for rapid combustion. The fuel is injected during the compression stroke. Only a small amount of fuel is injected into the cylinder, but the piston cavity positions the fuel in the vicinity of the spark plug, creating a pocket of high-density air-fuel mixture that makes combustion possible. A large volume of air remains in the cylinder, resulting in an ultra-lean air-fuel mixture overall. Once ignition takes place, the powerful swirl created by the i-VTEC system propagates efficiently, contributing to rapid combustion. These innovation result in an air-fuel ratio for the i-VTEC engine of 65 to 1, a level of ultra-lean combustion unheard up until now. Stable combustion is achieved with far less fuel than conventional direct injection engines, for which an air-fuel ratio of 40 to 1 was the limit. The result is enhanced fuel economy.

Fuel economy has also been improved during stoichiometric combustion, which takes place during moderate to high load conditions, such as rapid acceleration during city driving. The i-VTEC system causes one of the intake valves to remain closed, generating a powerful swirl pattern. VTC controls intake valve closure timing, for maximum intake efficiency. Fuel is injected during the intake stroke; the strong swirl pattern evenly disperses the air-fuel mixture for improved combustion efficiency. At the same time, a large volume of EGR gas is introduced, reducing pumping losses to promote better fuel economy. As a result, the new engine achieves a 20 percent increase in engine fuel efficiency over conventional 2-liter engines. Equipped with this new engine, the new Stream minivan delivers top of class fuel economy of 15 kilometers per liter.

During high-speed acceleration, aggressive driving and other high-load conditions, the new engine delivers ample output and torque. Fuel is injected during the intake stroke to obtain stoichiometric combustion, while i-VTEC mechanism opens both of intake valves for improved intake efficiency. Meanwhile, VTC provides optimal control over intake timing to insure maximum air intake. These innovations make the i-VTEC I the top performing engine in its class, with maximum output of 115 kilowatts and maximum torque of 188 Newton meters. A Stream equipped with a new engine combines fuel economy of the top of its class with powerful high-speed acceleration. The result is a combination of fuel economy and performance beyond the reach of conventional minivans.

Controlling nitrogen oxide emissions in lean burn direct injection engines is a key issue. With the new i-VTEC I, HONDA has gone all out to overcome that challenge. The new engine utilizes a high-precision EGR valve with large capacity and outstanding responsibleness. This delivers a large volume of exhaust gas to the cylinder, lowering the combustion temperature to reduce nitrogen oxide production. In addition to the high-density, three-stage catalytic converter, a newly developed high-performance catalyst helps scrub exhaust gases. Along with outstanding heat resistance, the nitrogen oxide adsorption catalytic converter offers improved durability and scrubbing performance, effectively reducing nitrogen oxide emissions. These innovations help the i-VTEC I achieve ultra-low emission levels and superior environmental performance.

The newly developed 2-liter DOHC i-VTEC I incorporates advanced HONDA technologies and intelligent control systems to achieve superior fuel economy, environmental performance at the top of its class and high power output. The new i-VTEC I, the next generation in direct-injection engines!

Modes of operation

I doubt about the three modes of combustion. According to Mitsubishi site there are just two different modes of combustion (Ultra Lean Mode and the Superior Output Mode)[1]. I believe the stoichiomeric mode and full power modes can be merged into one as the time of injection is same and the difference lies only in the air fuel ratio.Gaurav1146 14:22, 6 May 2005 (UTC)

I'm not sure. I don't have exact numbers for the air-fuel rate at high loads, but even if full power mode is close to stoichiometric, Honda GDI engine is distinct in using variable intake and VVT to increase torque at low RPM. Otherwise it uses very much the same approach however (see the transcript above).

I think we should first streamline the article by adding some some extra bits from these two presentations and then look if the disntinction remains. Meanwhile, I'll try to find some detailed info on the Direct Ecotec engine, so we can make some further generalisations. To start with, here's a small bit from 2004 GM Technology Preview Displays. DmitryKo 18:06, 6 May 2005 (UTC)

Well I saw a training video that Volkswagen put out about direct injection that idenified 3 modes of operation. I think it's a matter of the engineers and manufacturers.Mustang6172 07:37, 20 September 2006 (UTC)

"In full power mode, the air-fuel mixture is homogeneous as well and contains the maximum amount of fuel that is possible to ignite without knocking out, as defined by the compression ratio of the engine." This part needs attention. It would be more correct to say the minimum mass of fuel over the amount required for stoic that is possible to ignite without knocking. Also, the compression ratio doesn't alone dictate when a mix will knock/det. The mass of air in the chamber also plays a part. Zoolio 23:41, 17 November 2006 (UTC)

pump pressure

Does direct gasoline injection require high pressures similar to diesel injectors? I would guess injecting during the intake stroke doesn't, but injection during the compression stroke would, except that that mode is not operational during wide open throttle, so that it doesn't have to operate when the cylinders are fully filled.... ?? Gzuckier 15:31, 3 October 2005 (UTC)

Blonde2max 11:54, 28 April 2006 (UTC) Diesel engines have MUCH higher compression ratios- often double that of petrol cars

I have a question about "History" entry.

History The first direct injection system was developed by Bosch, and was introduced by Goliath and Gutbrod in 1952.

How first direct injection system was developed in 1952 if wiki page about DB 605 http://en.wikipedia.org/wiki/DB_605 states that it had direct fuel injection? Maybe first automotive direct injection system was developed in 52 but I wonder if it was any different from airplane.

Krzys

Additions to GDI page

Information on the most of the GDI products now available was missing from the Gasoline Direct Injection page. I added the names of four motorscooter manufacturers, three of the four outboard motor manufacturers, and a personal watercraft manufacturer. I also added information on why GDI is especially beneficial in two-stroke motors, and information on how GDI is being used to reduce deadly pollution in Southeast Asia and the Pacific. I am new to Wikipedia,and would appreciate any assistance in putting my additions into the proper format. I did include links to news articles and other sources to support my additions, and will work on the page to get it into the proper format when I have more time. --GT 08:01, 3 August 2007 (UTC)

Changes to GDI page

I've changed most references to "GDI" to simply "DI" for two reasons. First, the wikipedia page on fuel injection itself references it as DI, so the change is consistent. Second, "GDi" is a trademark of Mitsubishi, and only Mitsubishi systems are referred to as GDI or GDi. Other automotive manufacturers have other acronyms for their direct injection systems.

Perhaps the usage of DI should be further changed to MPFI, which is what this page is talking about.