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EspañolGASOLINE DIRECT INJECTION
(Redirected from Fuel Stratified Injection)
'Gasoline direct injection' or 'GDi' is a variant of fuel injection employed in modern two- and four- stroke petrol engines. The gasoline is highly pressurised, and injected via a common rail fuel line directly into the combustion chamber of each cylinder, as opposed to conventional multi point fuel injection that happens in the intake tract, or cylinder port. GDi enables stratified charge (ultra lean burn) combustion for improved fuel efficiency and emission levels at low load.
The major advantages of a GDi engine are increased fuel efficiency and high power output. This is achieved by the precise control over amount of fuel and injection timings which are varied according to the load conditions. In addition, there are no throttling losses when compared to a conventional fuel injected or carbureted engine, which greatly improves efficiency in engines without a throttle plate.
The engine management system continually chooses among three combustion modes: ultra lean burn, stoichiometric, and full power output. Each mode is characterized by the air-fuel ratio. The stoichiometric air-fuel ratio for petrol (gasoline) is 14.7 to 1 by weight, but ultra lean mode can involve ratios as high as 65 to 1. These leaner mixtures, much leaner than in a conventional engine, reduce fuel consumption.
★ 'Ultra lean' mode is used for light-load running conditions, when little or no acceleration is required. The fuel is not injected at the intake stroke but rather at the latter stages of the compression stroke, so that the small amount of air-fuel mixture is optimally placed near the spark plug. This stratified charge is surrounded by mostly air which keeps the fuel away from the cylinder walls for lowest emissions. The combustion takes place in a toroidal cavity on the piston's surface. This technique enables the use of ultra-lean mixtures impossible with carburetors or conventional fuel injection.
★ 'Stoichiometric' mode is used for moderate load conditions. Fuel is injected during the intake stroke, creating a fuel-air mixture in the cylinder. From the stoichiometric ratio, an optimum burn results in clean exhaust readily further cleaned by the catalytic converter.
★ 'full power' mode is used for rapid acceleration and heavy loads (as when climbing a hill). The air-fuel mixture is homogeneous and the ratio is slightly richer than stoichiometric, which helps prevent pinging. The fuel is injected during the intake stroke.
Direct injection may also be accompanied by other engine technologies such as variable valve timing and tuned or variable length intake manifolding. Water injection or (more commonly) exhaust gas recirculation can help reduce the high NOx emissions that result from burning ultra lean mixtures.
The first direct injection system was developed by Bosch, and was introduced by Goliath and Gutbrod in 1952. The 1955 Mercedes-Benz 300SL, the first sports car to use fuel injection, used direct injection. The Bosch fuel injectors were placed into the bores on the cylinder wall used by the spark plugs in other Mercedes-Benz six-cylinder engines (the spark plugs were relocated to the cylinder head). Later, more mainstream applications of fuel injection favoured less expensive indirect injection methods.
During the late 1970's, the Ford Motor Company developed a stratified-charge engine they called "ProCo" (programmed combustion),[1][2] utilizing a unique high pressure pump and direct injectors. One hundred Crown Victoria cars were built at Ford's Atlanta Assembly in Hapeville, Georgia utilizing a ProCo V8 engine. The project was canceled for several reasons; electronic controls, a key element, were in their infancy; pump and injector costs were extremely high; and lean combustion produced nitrogen oxides in excess of near future EPA limits. Also, the three way catalytic converter was proven to be a more cost effective solution.
It was not until 1996 that gasoline direct injection reappeared in the automotive market. Mitsubishi Motors was the first with a GDI engine in the Japanese market Galant/Legnum's ''4G93'' 1.8 L straight-4,[3] which it subsequently brought to Europe in 1997 in the Mitsubishi Carisma,[4] although Europe's high-sulphur fuel led to emissions problems, and fuel efficiency was less than expected.[5] It also developed the first six cylinder GDI powerplant, the ''6G74'' 3.5 L V6, in 1997.[6] Mitsubishi applied this technology widely, producing over one million GDI engines in four families by 2001,[7] PSA Peugeot Citroën and Hyundai Motors both licensed Mitsubishi's GDI technology in 1999, the latter using the first GDI V8.[8][9] DaimlerChrysler produced a special engine for 2000, offered only in markets with low sulphur fuel.
Although other companies have since developed gasoline direct injection engines, GDI (with an uppercase final "I") remains a registered trademark of Mitsubishi Motors.[10]
Toyota introduced direct injection engine D4 (Toyota AZ engine) in 2000 Toyota Avensis. Toyota's ''2GR-FSE'' V6 uses a combination of direct and indirect injection. It uses two injectors per cylinder, a traditional port injector and a new direct injector.
Later GDi engines have been tuned and marketed for their high performance. Volkswagen/Audi introduced their GDi engine in 2001, under the product name Fuel Stratified Injection (FSI), the technology adapted from Audi's Le Mans prototype racecar.
Alfa Romeo introduced their first direct injection engine JTS in 2002, and today the technology is used on almost every Alfa Romeo engine.
BMW introduced GDi V12 BMW N73 engine in 2003. This initial BMW system used low-pressure injectors and could not enter lean-burn mode, but the company introduced its second-generation High Precision Injection system on the updated N52 straight-6 in 2006. This system surpasses many others with a wider envelope of lean-burn time, increasing overall efficiency.[11] PSA is cooperating with BMW on a new line of engines which will make its first appearance in the 2007 MINI Cooper S.
General Motors had planned to produce a full range of GDi engines by 2002, but so far only two such engines have been introduced — in 2004, a version of the 2.2 L Ecotec used by the Opel Vectra and in 2005, a 2.0 L Ecotec with VVT technology for the Pontiac Solstice GXP, the Vauxhall GT, the Opel Speedster, and the Saturn Sky Red Line. The forthcoming 2008 Cadillac CTS and Cadillac STS will also be available GDi 3.6 L LLT engine due out in the fall of 2007.
In 2004 Isuzu Motors produced the first GDi engine sold in a mainstream American vehicle. Standard on the 2004 Axiom and optional on the 2004 Rodeo. Isuzu claimed the benefit of GDi is that the vaporizing fuel has a cooling effect, allowing a higher compression ratio (10.3 to 1 versus 9.1 to 1) that boosts output by 20 horsepower and that 0-to-60 times drop from 8.9 to just 7.5 seconds, with the quarter-mile being cut from 16.5 seconds to 15.8 ticks.[12]
Mazda uses their own version of direct injection in the Mazdaspeed 6 / Mazda 6 MPS, the CX-7 sport-ute, and the new Mazdaspeed 3. It is referred to as Direct Injection Spark Ignition.
The benefits of direct injection are even more pronounced in two-stroke engines, because it eliminates much of the pollution they cause. In conventional two-strokes, the exhaust and intake ports are both open at the same time, at the bottom of the piston stroke. A large portion of the fuel/air mixture entering the cylinder from the crankcase through the intake ports goes directly out, unburned, through the exhaust port. With direct injection, only air comes from the crankcase, and fuel is not injected until the piston rises and all ports are closed.
Two types of GDI are used in two-strokes: low-pressure air-assisted, and high pressure. The former, developed by Orbital Engine Corporation of Australia (now Orbital Corporation) injects a mixture of fuel and compressed air into the combustion chamber. When the air expands it atomizes the fuel into 8-micrometre droplets, very small relative to the 20 to 30-micrometre fuel droplets in other direct injection systems. The Orbital system is used in motor scooters manufactured by Aprilia, Piaggio, Peugeot and Kymco, in outboard motors manufactured by Mercury and Tohatsu, and in personal watercraft manufactured by Bombardier.
In the early 1990s, Ficht GmbH of Kirchseeon, Germany developed a high-pressure direct injector for use with two stroke engines. This injector was unique in that it did not require a high pressure pump but was still capable of generating enough pressure to inject into a closed combustion chamber. Outboard Marine Corporation (OMC) licensed the technology in 1995 and introduced it on a production outboard engine in 1996.[13][14] OMC purchased a controlling interest in Ficht in 1998.[15]
Beset by extensive warranty claims for its Ficht outboards,
OMC declared bankruptcy in December of 2000 and the engine manufacturing portion and brands (Evinrude Outboard Motors and Johnson Outboards), including the Ficht technology, were purchased by Bombardier in 2001.[16], [17]
Evinrude introduced the E-Tech system, an improvement to the Ficht fuel injection, in 2003, based on U.S. patent 6,398,511. In 2004, Evinrude received the EPA Clean Air Excellence Award for their outboards utilizing the E-Tech system.[18]
Yamaha also has a high-pressure direct injection system for two-stroke outboards. It differs from the Ficht/E-Tech and Orbital direct injection systems because it uses a separate, belt driven, high pressure, mechanical fuel pump to generate the pressure necessary for injection in a closed chamber. This is similar to most current 4-stroke automotive designs.
EnviroFit, a non-profit corporation sponsored by Colorado State University, has developed direct injection retrofit kits for two-stroke motorcycles in a project to reduce air pollution in Southeast Asia, using technology developed by Orbital Corporation of Australia.[19]
The World Health Organization says air pollution in Southeast Asia and the Pacific causes 537,000 premature deaths each year. The 100-million two-stroke taxis and motorcycles in that part of the world are a major cause.[20] [21]
1. "Detroit's "Total Revolution"", ''TIME magazine'', March 19 1979
2. "Will gasoline direct injection finally make it?", Csaba Csere, ''Car and Driver'', June 2004
3. "Latest MMC technologies and near-future goals: GDI - The pursuit of a high-efficiency engine", Mitsubishi Motors website
4. "European Launch for GDI CARISMA", Mitsubishi Motors press release, August 29 1997
5. "Direct Injection Petrol engine - Mitsubishi GDI", Mark Wan, AutoZine Technical School
6. "Mitsubishi Motors Adds World First V6 3.5-liter GDI Engine to Ultra-efficiency GDI Series", Mitsubishi Motors press release, April 16 1997
7. "GDI1 engine production tops 1,000,000 unit mark", Mitsubishi Motors press release, September 11 2001
8. "Mitsubishi Motors and PSA Peugeot Citroen Reach Agreement on GDI Engine Technical Cooperation", Mitsubishi Motors press release, January 12 1999
9. "Mitsubishi Motors Supplies Hyundai Motor Co. with GDI Technology for New V8 GDI Engine", Mitsubishi Motors press release, April 28 1999
10. "GDI-ASG Pistachio", Mitsubishi Motors press release, September 28 1999
11. Inside BMW's Latest Powertrain Technologies
12. "Isuzu Direct-Injection V6", ''Popular Science'', 2003
13. "OMC and Ficht announce stategic alliance", PR Newswire, July 24 1995
14. " OMC Ficht fuel injection engines hit the market", PR Newswire, July 31 1996
15. "Marriage Made in Boat Heaven", ''Sarasota Herald-Tribune'', December 26 1998
16. "Canadian, German Companies Buy Assets of Waukegan, Ill., Boating Company", ''St. Louis Post-Dispatch'', March 26 2001
17. http://findarticles.com/p/articles/mi_m0BQK/is_2_6/ai_71766946
18. "2004 Clean Air Excellence Awards Recipients", EPA website, 2004
19. Envirofit works to retrofit the Philippines
20. http://www.ernasia.org/index.php?option=com_content&task=view&id=313&Itemid=75
21. http://www.worldwatch.org/node/5267
★ Aprilia 2-stroke direct injection technology comparison
★ Orbital Corporation's direct injection technology
★ Mitsubishi's Page on Gasoline Direct Injection
★ Synerject LLC
★ Envirofit
★ Ucal Fuel Systems Limited
'Gasoline direct injection' or 'GDi' is a variant of fuel injection employed in modern two- and four- stroke petrol engines. The gasoline is highly pressurised, and injected via a common rail fuel line directly into the combustion chamber of each cylinder, as opposed to conventional multi point fuel injection that happens in the intake tract, or cylinder port. GDi enables stratified charge (ultra lean burn) combustion for improved fuel efficiency and emission levels at low load.
| Contents |
| Theory of operation |
| History |
| In two-stroke engines |
| References |
| External links |
Theory of operation
The major advantages of a GDi engine are increased fuel efficiency and high power output. This is achieved by the precise control over amount of fuel and injection timings which are varied according to the load conditions. In addition, there are no throttling losses when compared to a conventional fuel injected or carbureted engine, which greatly improves efficiency in engines without a throttle plate.
The engine management system continually chooses among three combustion modes: ultra lean burn, stoichiometric, and full power output. Each mode is characterized by the air-fuel ratio. The stoichiometric air-fuel ratio for petrol (gasoline) is 14.7 to 1 by weight, but ultra lean mode can involve ratios as high as 65 to 1. These leaner mixtures, much leaner than in a conventional engine, reduce fuel consumption.
★ 'Ultra lean' mode is used for light-load running conditions, when little or no acceleration is required. The fuel is not injected at the intake stroke but rather at the latter stages of the compression stroke, so that the small amount of air-fuel mixture is optimally placed near the spark plug. This stratified charge is surrounded by mostly air which keeps the fuel away from the cylinder walls for lowest emissions. The combustion takes place in a toroidal cavity on the piston's surface. This technique enables the use of ultra-lean mixtures impossible with carburetors or conventional fuel injection.
★ 'Stoichiometric' mode is used for moderate load conditions. Fuel is injected during the intake stroke, creating a fuel-air mixture in the cylinder. From the stoichiometric ratio, an optimum burn results in clean exhaust readily further cleaned by the catalytic converter.
★ 'full power' mode is used for rapid acceleration and heavy loads (as when climbing a hill). The air-fuel mixture is homogeneous and the ratio is slightly richer than stoichiometric, which helps prevent pinging. The fuel is injected during the intake stroke.
Direct injection may also be accompanied by other engine technologies such as variable valve timing and tuned or variable length intake manifolding. Water injection or (more commonly) exhaust gas recirculation can help reduce the high NOx emissions that result from burning ultra lean mixtures.
History
The first direct injection system was developed by Bosch, and was introduced by Goliath and Gutbrod in 1952. The 1955 Mercedes-Benz 300SL, the first sports car to use fuel injection, used direct injection. The Bosch fuel injectors were placed into the bores on the cylinder wall used by the spark plugs in other Mercedes-Benz six-cylinder engines (the spark plugs were relocated to the cylinder head). Later, more mainstream applications of fuel injection favoured less expensive indirect injection methods.
During the late 1970's, the Ford Motor Company developed a stratified-charge engine they called "ProCo" (programmed combustion),[1][2] utilizing a unique high pressure pump and direct injectors. One hundred Crown Victoria cars were built at Ford's Atlanta Assembly in Hapeville, Georgia utilizing a ProCo V8 engine. The project was canceled for several reasons; electronic controls, a key element, were in their infancy; pump and injector costs were extremely high; and lean combustion produced nitrogen oxides in excess of near future EPA limits. Also, the three way catalytic converter was proven to be a more cost effective solution.
It was not until 1996 that gasoline direct injection reappeared in the automotive market. Mitsubishi Motors was the first with a GDI engine in the Japanese market Galant/Legnum's ''4G93'' 1.8 L straight-4,[3] which it subsequently brought to Europe in 1997 in the Mitsubishi Carisma,[4] although Europe's high-sulphur fuel led to emissions problems, and fuel efficiency was less than expected.[5] It also developed the first six cylinder GDI powerplant, the ''6G74'' 3.5 L V6, in 1997.[6] Mitsubishi applied this technology widely, producing over one million GDI engines in four families by 2001,[7] PSA Peugeot Citroën and Hyundai Motors both licensed Mitsubishi's GDI technology in 1999, the latter using the first GDI V8.[8][9] DaimlerChrysler produced a special engine for 2000, offered only in markets with low sulphur fuel.
Although other companies have since developed gasoline direct injection engines, GDI (with an uppercase final "I") remains a registered trademark of Mitsubishi Motors.[10]
Toyota introduced direct injection engine D4 (Toyota AZ engine) in 2000 Toyota Avensis. Toyota's ''2GR-FSE'' V6 uses a combination of direct and indirect injection. It uses two injectors per cylinder, a traditional port injector and a new direct injector.
Later GDi engines have been tuned and marketed for their high performance. Volkswagen/Audi introduced their GDi engine in 2001, under the product name Fuel Stratified Injection (FSI), the technology adapted from Audi's Le Mans prototype racecar.
Alfa Romeo introduced their first direct injection engine JTS in 2002, and today the technology is used on almost every Alfa Romeo engine.
BMW introduced GDi V12 BMW N73 engine in 2003. This initial BMW system used low-pressure injectors and could not enter lean-burn mode, but the company introduced its second-generation High Precision Injection system on the updated N52 straight-6 in 2006. This system surpasses many others with a wider envelope of lean-burn time, increasing overall efficiency.[11] PSA is cooperating with BMW on a new line of engines which will make its first appearance in the 2007 MINI Cooper S.
General Motors had planned to produce a full range of GDi engines by 2002, but so far only two such engines have been introduced — in 2004, a version of the 2.2 L Ecotec used by the Opel Vectra and in 2005, a 2.0 L Ecotec with VVT technology for the Pontiac Solstice GXP, the Vauxhall GT, the Opel Speedster, and the Saturn Sky Red Line. The forthcoming 2008 Cadillac CTS and Cadillac STS will also be available GDi 3.6 L LLT engine due out in the fall of 2007.
In 2004 Isuzu Motors produced the first GDi engine sold in a mainstream American vehicle. Standard on the 2004 Axiom and optional on the 2004 Rodeo. Isuzu claimed the benefit of GDi is that the vaporizing fuel has a cooling effect, allowing a higher compression ratio (10.3 to 1 versus 9.1 to 1) that boosts output by 20 horsepower and that 0-to-60 times drop from 8.9 to just 7.5 seconds, with the quarter-mile being cut from 16.5 seconds to 15.8 ticks.[12]
Mazda uses their own version of direct injection in the Mazdaspeed 6 / Mazda 6 MPS, the CX-7 sport-ute, and the new Mazdaspeed 3. It is referred to as Direct Injection Spark Ignition.
In two-stroke engines
The benefits of direct injection are even more pronounced in two-stroke engines, because it eliminates much of the pollution they cause. In conventional two-strokes, the exhaust and intake ports are both open at the same time, at the bottom of the piston stroke. A large portion of the fuel/air mixture entering the cylinder from the crankcase through the intake ports goes directly out, unburned, through the exhaust port. With direct injection, only air comes from the crankcase, and fuel is not injected until the piston rises and all ports are closed.
Two types of GDI are used in two-strokes: low-pressure air-assisted, and high pressure. The former, developed by Orbital Engine Corporation of Australia (now Orbital Corporation) injects a mixture of fuel and compressed air into the combustion chamber. When the air expands it atomizes the fuel into 8-micrometre droplets, very small relative to the 20 to 30-micrometre fuel droplets in other direct injection systems. The Orbital system is used in motor scooters manufactured by Aprilia, Piaggio, Peugeot and Kymco, in outboard motors manufactured by Mercury and Tohatsu, and in personal watercraft manufactured by Bombardier.
In the early 1990s, Ficht GmbH of Kirchseeon, Germany developed a high-pressure direct injector for use with two stroke engines. This injector was unique in that it did not require a high pressure pump but was still capable of generating enough pressure to inject into a closed combustion chamber. Outboard Marine Corporation (OMC) licensed the technology in 1995 and introduced it on a production outboard engine in 1996.[13][14] OMC purchased a controlling interest in Ficht in 1998.[15]
Beset by extensive warranty claims for its Ficht outboards,
OMC declared bankruptcy in December of 2000 and the engine manufacturing portion and brands (Evinrude Outboard Motors and Johnson Outboards), including the Ficht technology, were purchased by Bombardier in 2001.[16], [17]
Evinrude introduced the E-Tech system, an improvement to the Ficht fuel injection, in 2003, based on U.S. patent 6,398,511. In 2004, Evinrude received the EPA Clean Air Excellence Award for their outboards utilizing the E-Tech system.[18]
Yamaha also has a high-pressure direct injection system for two-stroke outboards. It differs from the Ficht/E-Tech and Orbital direct injection systems because it uses a separate, belt driven, high pressure, mechanical fuel pump to generate the pressure necessary for injection in a closed chamber. This is similar to most current 4-stroke automotive designs.
EnviroFit, a non-profit corporation sponsored by Colorado State University, has developed direct injection retrofit kits for two-stroke motorcycles in a project to reduce air pollution in Southeast Asia, using technology developed by Orbital Corporation of Australia.[19]
The World Health Organization says air pollution in Southeast Asia and the Pacific causes 537,000 premature deaths each year. The 100-million two-stroke taxis and motorcycles in that part of the world are a major cause.[20] [21]
References
1. "Detroit's "Total Revolution"", ''TIME magazine'', March 19 1979
2. "Will gasoline direct injection finally make it?", Csaba Csere, ''Car and Driver'', June 2004
3. "Latest MMC technologies and near-future goals: GDI - The pursuit of a high-efficiency engine", Mitsubishi Motors website
4. "European Launch for GDI CARISMA", Mitsubishi Motors press release, August 29 1997
5. "Direct Injection Petrol engine - Mitsubishi GDI", Mark Wan, AutoZine Technical School
6. "Mitsubishi Motors Adds World First V6 3.5-liter GDI Engine to Ultra-efficiency GDI Series", Mitsubishi Motors press release, April 16 1997
7. "GDI1 engine production tops 1,000,000 unit mark", Mitsubishi Motors press release, September 11 2001
8. "Mitsubishi Motors and PSA Peugeot Citroen Reach Agreement on GDI Engine Technical Cooperation", Mitsubishi Motors press release, January 12 1999
9. "Mitsubishi Motors Supplies Hyundai Motor Co. with GDI Technology for New V8 GDI Engine", Mitsubishi Motors press release, April 28 1999
10. "GDI-ASG Pistachio", Mitsubishi Motors press release, September 28 1999
11. Inside BMW's Latest Powertrain Technologies
12. "Isuzu Direct-Injection V6", ''Popular Science'', 2003
13. "OMC and Ficht announce stategic alliance", PR Newswire, July 24 1995
14. " OMC Ficht fuel injection engines hit the market", PR Newswire, July 31 1996
15. "Marriage Made in Boat Heaven", ''Sarasota Herald-Tribune'', December 26 1998
16. "Canadian, German Companies Buy Assets of Waukegan, Ill., Boating Company", ''St. Louis Post-Dispatch'', March 26 2001
17. http://findarticles.com/p/articles/mi_m0BQK/is_2_6/ai_71766946
18. "2004 Clean Air Excellence Awards Recipients", EPA website, 2004
19. Envirofit works to retrofit the Philippines
20. http://www.ernasia.org/index.php?option=com_content&task=view&id=313&Itemid=75
21. http://www.worldwatch.org/node/5267
External links
★ Aprilia 2-stroke direct injection technology comparison
★ Orbital Corporation's direct injection technology
★ Mitsubishi's Page on Gasoline Direct Injection
★ Synerject LLC
★ Envirofit
★ Ucal Fuel Systems Limited
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