The Story Of Fuel Injection

in the internal combustion engine a tank full of liquid fuel is directly unusable it must first be prepared to be efficiently combined with oxygen this process begins with a careful metering of fuel flow in order to stoichiometrically match the expected oxygen content at the point of ignition the fuel is then broken down into smaller droplets or atomized dramatically increasing its surface area it's then emulsified with air where it vaporizes and in this Vapor State effective combustion can finally occur and useful work extracted the exact nature of how these three stages are executed has been under constant development for over 140 years becoming a key element to the advancement of the internal combustion engine early on in the history of the internal combustion engine carburation was developed to both meter and vaporized fuel invented by Samuel Mori in 1826 the carburetor operates on the principle of drawing and fuel using the airflow created by aspiration his developments were the result of years of experimentation with flammable Vapors and combustion in fact early carburetors operated by passing an airflow over the surface of a volatile fuel where vaporization would occur at the interface as the internal combustion engine grew more sophisticated carburetors would evolve into venturi-based devices that utilized complementing mechanical circuits in order to accurately meter and atomize fuel across a broad range of engine conditions however despite its Simplicity carburation would prove problematic for heavier less volatile fuel oils a new approach to delivering more viscous fuels for combustion was needed in 1872 American mechanical engineer and inventor Georgia Bailey Brayton had patented a unique internal combustion engine design known as the constant pressure internal combustion engine known as Brighton's ready motor his two-stroke design had two Pistons mounted to a common connecting rod the smaller of the two Pistons functioned as an air pump compressing air to around four and a half bar flammable gases mixed with the air as it enters and the compressed air fuel mixture is passed through a valve and stored in a reservoir an engine driven camshaft would then open a valve that allowed the pressurized air fuel mixture to flow from the reservoir into the larger combustion cylinder then as the mixture enters the combustion cylinder it is passed through a layer of flame arresting wire mesh where it's ignited by a constant burning pilot flame the combusting and expanding gases generated around a four bar of pressure creating the power stroke simultaneously the small piston is brought towards the top dead center in its cylinder compressing the subsequent charge of air brayton's engines suffered from a fatal flaw if the flame arresting mesh failed the ignition Source could run back into the reservoir for the air fuel mixture leading to an explosion to counter this Hazard Brayden would go on to develop a system that used compressed air created by the engine to blast liquid fuel oil into the induction pipe of the combustion chamber onto a porous material as the liquid fuel is heated by the engine and vaporized it mixes with the air charge being admitted into the cylinder eliminating the explosion hazard by 1874 Braden would file a patent for his Air Blast injection mechanism making it the first liquid fuel injection system brain's engine would quickly evolve achieving commercial success and powering various vehicles for a few years but it would soon be overtaken by the more popular Auto cycle engine brayton's Air Blast fuel injection concept would resurfaced almost two decades later when German inventor Rudolph diesel struggled to figure out how to fuel his new highly efficient engine design Diesel's engine much like brayton's later engines operated on fuel oil however unlike most other engine designs of the time it did not require an ignition Source but rather relied on the elevated temperature of the mechanically compressed air within the cylinder to ignite the incoming fuel initially diesel attempted an injection system based on a mechanically driven accumulator however this would prove to be insufficient due to the high viscosity of the fuel used ultimately he would successfully adopt a high pressure Air Blast injection system similar to that of Brayton fuel oil was metered and delivered by a metering pump to an atomizer the atomizer was driven by high pressure air from a storage tank which itself is supplied by an attached air compressor when ejection occurred the injector valve was opened by a cam actuated mechanism and high pressure air then flowed into the engine cylinder carrying with it a metered finely atomized spray of fuel despite the success of Diesel's engine for many years he would revisit mechanical injection with some minor successes though the process remained impractical due to pump design limitations around the turn of the 20th century a new type of airless injection system began to appear among various engine manufacturers that used a plunger mechanism to deliver fuel at high pressure in this design fuel oil was delivered by a metering pump to a spring-loaded plunger which was compressed by an engine driven cam as the cam released the spring fuel would be injected into the engine cylinder as the spring returned the plunger to its bottom position plunger pumps were easily synchronized with the engine however these early designs still relied on a separate metering pump to control the supply of delivered fuel the plunger style injection mechanism would evolve incorporating metering into its function known as a jerk pump these designs used a helix feature on the pump's plunger that could be rotated allowing field to be variably bypassed through a spill Port during the pump stroke as diesel engines expanded in complexity and multiple cylinders became common a new injection system that utilized a rotary distribution pump began to appear pioneered by Francois feigns of Belgium in 1913. these types of pumps had only one fuel metering plunger mechanism a spinning rotor would make a hydraulic connection with the different ports on a distributor's head each feeding a cylinder this design only required one plunger allowing it to produce a more consistent fuel distribution as well as a smaller overall package these systems also benefited from having fewer moving Parts than inline jerk pumps feeding each cylinder that same year Vickers limited of England would develop its own multiple cylinder fueling system called common rail injection in common rule injection a multi-plunger pump delivers fuel to an accumulator where the fuel pressure is maintained by a relief valve the accumulator also functioned as a header supplying each cylinder's injector nozzle metering off the fuel was accomplished by varying the period of opening of the injection valve the flexibility of this design made it an appealing choice in fact the fundamentals of common rail injection can still be found in most modern diesel engines the field delivery nozzles of Diesel Injection systems had also simultaneously evolved early systems operated on Lower pressures and used a simple poppet type valve as fuel injection went airless fuel pressure is between 200 to 340 bar or about 3 000 to 5000 PSI became common and injection nozzles that utilized an inwardly opening valve started to appear this configuration would grow both in popularity and sophistication allowing for more complex spray patterns and handling fuel pressures well above 2000 bar or about 30 000 PSI one notable variation was the pencil valve first patented by Peter Bowman of Denmark in 1910 the Pendle protruded through the spray hole to produce an annular orifice that produced a spray pattern that offered excellent atomization and throttling characteristics in diesel engines even today pencil-based injectors are common across most forms of fuel injection due to these characteristics common rail diesel injectors which were activated externally would see a move from mechanical to electromechanical control during the 1930s with the atlas Imperial diesel engine company of California being the first to announce such a system these injectors further enhanced the common rail system's flexibility by fully decoupling injection timing from the engine early on there were many experiments to simplify the complexity of Diesel Injection in 1905 Carl Weedman made one of the first known successful attempts by combining the injector pump and the injector into a single mechanism known as a unit injector unit injectors are compact designs that use a traditional plunger pump to create high fuel pressures mechanically however unlike traditional systems the plunger and injector blend into one unit that delivers a fuel spray to the combustion chamber the commercial usage of unit injectors began in the early 1930s and became common in large diesel engines particularly in Marine use well into the 1920s fuel injection was primarily seen as a component of fuel oil engines for decades engines fueled by gasoline and other similarly volatile fuels operated adequately by carburation how however with the Advent of Aviation carburetors would now have to deal with the forces and altitude changes of flight many aircraft engine designers sought to bypass this complication altogether with gasoline fuel injection the first gasoline fuel injection systems were crewed and operated indirectly pre-mixing with air just before entering a cylinder these injection systems first began to appear around 1900. one notable example was Leon levovosaurus Antoinette 8v aircraft engine painted in 1902 it was not only the world's first V8 engine but it employed one of the first crude forms of gasoline fuel injection and love of a swords design a belt driven fuel pump at the rear of the engine fed fuel into a smaller injector Reservoir above each intake valve when the intake valve opened the air draw also pulled in fuel from the reservoir via a narrow capillary passageway within two decades direct gasoline fuel injection that operated in a manner similar to diesel jerk pump systems would start appearing on aircraft engines these injection systems operated at far lower pressures typically 30 to 40 bar and offered Superior mixture consistency over carburetors as well as eliminating backfire they were also more immune to the highly Dynamic operating environment of an aero engine by World War II direct gasoline injection expanded in popularity in Germany most aircraft engines ran on direct injection systems most of which were supplied by Bosch while in Japan Mitsubishi powered their Kinsey and Kasi radio aircraft engines with the technology the right Cyclone series engines and later versions of the Rolls-Royce Merlin engines or other noteworthy applications of direct gasoline injection after World War II amidst post-war recovery Germany's dominance of gasoline fuel injection technology would resurface in 1952 Bosch introduced an automotive version of their gasoline direct injection system derived from the db601 V12 used on the messerschmidt bf-109e this system would make its debut on the two-stroke engines of the good broad Superior 600 and the Goliath gp700 the Bosch system also doubled as an oil injection mechanism that lubricated the two-stroke engines in these vehicles allowing oil to be precisely metered into the fuel system from a secondary tank Bosch's system was so successful it would be fitted to several notable race cars including the race version of the Mercedes-Benz 300 SL and the w196 Grand Prix car Mercedes victories at Le Mans meal miglia and in Formula 1 demonstrated the power advantages fuel injection could provide in racing however Bosch's direct injection system was expensive and operated at very high pressures it also lacked the refinements needed for common use road cars during the 1950s manufacturers began to pursue a more practical form of gasoline fuel injection suitable for mass production from these developments came the introduction of mass-produced manifold fuel injection systems manifold fuel injection introduces fuel Upstream of the cylinder mixing it with air within the intake track often just before the intake valve while not as efficient as direct injection this approach allowed for significantly lower system pressures inherently reducing component costs one notable example of this was the General Motors Rochester Ramjet system developed by their Rochester product division for the 1957 Corvette this purely mechanical constant flow system worked by creating a vacuum signal at the throttle body that regulated fuel flow based on engine load fuel was first pumped from the fuel tank into a reservoir Bowl similar to a carburetor where it was fed through a gear pump that pressurized it to around 13.7 bar or 200 PSI the high pressure fuel flow was regulated via a bypass valve where it was then fed to the intake manifold injectors that supplied each cylinder the lower operating pressures of the system allowed for far simpler and cheaper to manufacture spur gear pump it also Incorporated features that improved drivability such as cold start fuel enrichment and overrun fuel cutoff at the time the performance advantage of V8s equipped with the Rochester system was acclaimed for attaining The elusive one horsepower per cubic inch mark during the same time period Bosch introduced its own indirect mechanical injection system for the new Mercedes-Benz 220se though unlike GM's system it used timed low pressure injection that regulated fuel Flow by varying the injected fuel flow duration this was accomplished by using a unique camshaft within the pump that was designed with a variable lobe that adjusted fuel flow based on the engine's operating conditions effectively making it one of the first forms of fuel mapping in addition to engine load Bosch's System Incorporated RPM air temperature and ambient pressure sensing into its design on the Mercedes-Benz 220se this resulted in 18 percent more power and 8 percent better fuel economy over the twin carburetor version Bosch's system was so successful it would be fitted to Mercedes entire line of top tier vehicles Bosch's timed approach would also be emulated over the next decade by several other manufacturers making appearances in a handful of vehicle lines throughout the 1960s it was during this decade that the United States Environmental Protection Agency created legislation that would set new limits on Automotive exhaust emissions beginning in 1968. the Precision and flexibility offered by Fuel Injection allowed manufacturers to meet these regulations without adding additional costly emissions compliance subsystems further motivating its development for Mass adoption timed fuel injection systems in particular proved to be superior to both constant flow injection and carburation in meeting these new standards however existing systems operated on a fuel pump that required extremely close tolerances and were expensive to manufacture this was due to the fact that they needed to provide not only the requisite fuel pressure but also the determined injection timing in fuel quantity during the mid-1950s the use of low pressure manifold-based gasoline mechanical fuel injection began to appear within a handful of vehicles these early systems implemented airflow sensing and fuel metering mechanically some of these mechanisms were even barred from existing carburetor designs however one company in particular took a completely different approach to the concept in 1955 engineers at Bendix took note of the recent introduction of the commercial transistor and its potential for automotive use Bendix theorized that by combining electromechanically operated solenoid fuel injectors with transistor-based electronic air sensing and fuel metering a more versatile and less mechanically complex form of fuel injection could be created this novel approach led to the introduction of the first electronic fuel injection system the Bendix electrojector in 1957. in bendex's system fuel at a constant pressure of 1.3 bar or about 20 psi was supplied by a non-metering electric fuel pump to electrically actuated solenoid fuel injectors located within the intake manifold and aimed at each intake valve the fuel pressure was regulated by a combination of an inline restriction and a return line which also purged air and vapor from the fuel line the engine's distributor was modified to incorporate a second rotor and set of contacts known as the trigger selector unit this unit was used to electrically tie the injector of the firing piston to the control Electronics allowing the system to match both the rotational speed and piston timing of the engine in a manner similar to the ignition system what made the electro injector system remarkable for its day was how it controlled fuel flow each injector was metered by pulse width modulation where the open time or duty cycle was determined by a pulse width metering was accomplished through an analog electronic modulator unit that modified the injector pulse width primarily using sensors that measured intake manifold pressure and air temperature the vacuum created within the intake manifold directly corresponded to the airflow into the engine when combined with a measure of the Air's density via its temperature the air mass and required fuel quantity can be determined this method for determining air mass is known as the speed density system additionally other electromechanical control elements modified the pulse width in a manner similar to a carburetor these included an idle mixture control circuit acceleration enrichment circuit deceleration cutoff circuit starting enrichment circuit and an altitude compensation circuit bendix's electronic fuel injection system was so far ahead of its time that its use of a common rail timed or sequential multi-point fuel injection system metered by RPM manifold pressure and air temperature can still be found as a part of many modern gasoline engine fuel injection systems the electro ejector system was first offered by AMC in 1957 as an option on the Rambler Rebel the next year Chrysler would also offer the system in the 1958 Chrysler 300D DeSoto Adventurer Dodge custom Royal Lancer d500 and Plymouth Fury ultimately the sophistication of bendix's system became its downfall as it proved to be far too unreliable for vehicle use this was attributed to cost cutting measures due to the high prices of early transistors this forced the use of failure prone lower quality capacitors to keep the system's costs down the operating environment was also harsher than anticipated for the sensitive electrical connections used particularly in sealing against moisture the electric ejector system would eventually be phased out in late 1958 due to excessive customer complaints with little more than 50 cars ever being built with the system it was so unreliable that Chrysler had even offered to replace it with carburetors at no charge over the next decade electronic fuel injection would be relegated to an experimental Endeavor due to the infancy of the electronic industry at the time despite this Bosch would still pursue electronic fueling control as an evolution to its successful mechanical systems in 1965 Bosch had licensed the patents for the problematic Bendix electro-ejector system and began to Leverage The then recent massive leaps in reliability and cost reduction the electronics Industry had made from this Bosch introduced their first electronic fuel injection system called jetronic in the Autumn of 1967 on the Volkswagen 1600 Le and tle the jetronic system was effectively a refinement of the electro ejector system it operated in a similar manner utilizing solenoid injectors a constant pressure common fuel rail and a distributor based ejector selection system however unlike electric most earlier implementations grouped the injector operation into Banks of two or three much like the Electric System the jetronic electronic control units or ECU was completely analog performing all of its functions with just 25 transistors however because it used more resilient capacitors that could withstand heat cycling and housed off its components on a single circuit board within a metal o-ring sealed case it was far more reliable than bendix's system drivability of vehicles equipped with jetronic was also very well received with the power output being comparable to multiple carburetor setups of the day the system also inherently reduced exhaust emissions and decreased fuel consumption particularly in City Driving due to the tighter control of fueling and fuel cutoff on deceleration the Bosch jetronic system lasted over a decade in production use with its final appearance being on Jaguar's xj12 V12 engine in 1979. despite the success of electronic fuel injection in the early 1970s Bosch would once again return to mechanical fuel injection with the introduction of its cage electronic mechanical continuous injection system this new nomenclature of the jektronic trademark also resulted in the retroactive branding of the original jetronic system to de jetronic the cage electronic system fundamentally was similar to GM's mechanical Rochester Ramjet system described in part one it operated by pumping fuel to a large control valve mechanism called a fuel distributor which mechanically metered the constant flow of fuel from there this metered fuel was then distributed to spring-loaded check valve injector nozzles located at each cylinder what made cage electronic unique is how it metered fuel the fuel distributor was mounted to a calibrated control vein in which intake air passed through the fuel volume supplied to the injectors was varied based on the angle of this moving vein effectively forming one of the first commercial volume airflow sensor-based fuel injection systems a secondary mechanism known as a control pressure regulator simultaneously adjusted the operating fuel pressure of the air metering system to better match the operating state of the engine electromechanical Regulators were utilized to adjust fueling during specific operating conditions in a manner similar to the digitronic system these included engine warm-up acceleration deceleration and altitude compensation the cage electronic system had proved to be so reliable and robust that its use spanned over two decades initially debuting in 1973 on the Porsche 911t it would soon be found on vehicles for most of Europe's major manufacturers throughout the 1980s with its final application being on the 1994 Porsche 911 Turbo 3.6 up until the mid-1970s the primary objectives of fuel injection tend to focus around fuel efficiency drivability and performance however with the introduction of legislation that restricted Automotive exhaust emissions in the late 1960s fuel injection would now become a critical tool in meeting these new requirements vehicle manufacturers look to several add-on devices to reduce emissions and among them the catalytic converter proved to Be an Effective solution to reducing carbon monoxide and unburned hydrocarbons catalytic converters however tend to require an air fuel mixture around the stoichiometric point of gasoline in order to operate efficiently it was soon realized that fuel injection was the most effective method to easily and consistently maintain these ratios particularly under partial throttle cruising conditions because this target window was so narrow and oxygen or Lambda sensor would be placed within the exhaust stream creating a closed loop feedback system that would permit a fuel metering mechanism to closer achieve an ideal air fuel mixture for efficient catalytic converter operation the early integration of Lambda sensors into fuel injection was relatively crude and tended to be a modification of existing open loop designs that enabled the use of a catalytic converter Bosch's Lambda equipped cage uptronic variants for example employed a frequency valve which essentially was a modified solenoid fuel injector inserted into one of the lines of its fuel distributor the frequency valve operated in parallel with the other two fuel regulating mechanisms offering a finer level of fuel flow control this valve was electronically driven by an analog control circuit that varied fuel pressure within the fuel distributor in response to a signal produced by the engine's oxygen sensor this allowed an ideal mixture to be maintained for a catalytic converter operation under partial throttle conditions as fuel injection moved into the 1980s the lowering costs and increasing reliability of electronics led to more electronic control and fuel injection control units would now grow in sophistication while simultaneously the accompanying engine sensors that drove them became more standardized in the automotive industry Bosch would extend the inline electromechanical flow control technique first to use on its Lambda sensor variants to its ke jetronic system transitioning fuel metering further to electronic control ultimately a fully electronic system would be embraced with the introduction of lgtronic in 1974. much like the original djtronic system l-jetronic employed a constant pressure common fuel rail to supply each solenoid injector however unlike djtronic injection timing and duty cycle was determined fully electronically within the engine control unit the l-chronic ECU metered fuel using an airflow meter combined with sensors that measure throttle position engine temperature air temperature and an engine speed signal from the distributor it also Incorporated a signal from an oxygen sensor for emissions compliance El jatronic rapidly grew in popularity and was used heavily in 1980s era European cars as well as BMW's k-series motorcycles Bosch would go on to license components of its technology to Lucas Hitachi Automotive Products and Nippon Denso for use by Asian car manufacturers Kawasaki would even use a variant of the system on their 1980s z1000 H1 making it the first fuel injection system to appear on a production motorcycle during the second half of the 1970s microprocessors were becoming more capable as well as cheaper to manufacture several major manufacturers particularly in the United States began exploring their use in a supplementary capacity to meet emissions requirements they were initially employed in a limited manner alongside analog and mechanical systems for fuel metering control both in carburetors and mechanical fuel injection and for ignition control finally By 1979 the first fully digital engine management fuel injection system called motronic would be introduced by Bosch shortly after both Motorola and Delphi Automotive Systems would offer their own fully digital systems much like its electronic analog counterpart these systems all used in engine control unit to vary the duty cycle of solenoid fuel injectors fed by constant fuel pressure to meter fuel however unlike analog and mechanical systems digital ecu's do not directly tie the various engine sensors to the injector control signal but rather convert them to a digital value and indirectly determine the ideal injector duty cycle for a given engine State completely in software in non-digital fuel injection control how an engine's sensors impact fuel metering was determined during the system's design and was relatively difficult to modify furthermore the fine controlling complex intermixing of these signal relationships were either not possible or impractical to implement with the Advent of digital engine management a finer more complex level of control can now be accomplished while simultaneously offering incredible versatility with sensor signals and their impact on fuel metering now modeled in software changes could now be made more rapidly and at any time by modifying elements of the ecu's programming digital ecu's generally operate by using a lookup table called a map that assigns an output parameter to a combination of sensor readings typically in air sensing strategy is used to form a primary fuel metering map with layers of additional Maps based on various sensor inputs modifying the space map the cumulative effect of these outputs is then used to determine the duty cycle of the appropriate fuel injector many modern fuel injection systems employ some combination of manifold pressure sensing vein-based volume flow sensing or mass flow sensing as the basis for their air sensing strategy air mass flow sensing in particular was introduced during the 1980s as manufacturers began to fully Embrace digital electronic fuel injection mass airflow sensors typically operate by placing a wire heated by a constant voltage within the intake Airstream as air flows past the wire the wire cools decreasing its resistance providing an accurate measure of the mass of air moving through it and some Modern engine management systems manifold pressure and mass airflow sensing are combined into a hybrid strategy to achieve better fuel economy and engine performance engine ignition would also integrate into these Management Systems ignition timing could now be implemented fully in software using the find control offered by ECU ignition mapping engine knock sensing would also be integrated allowing software to constantly adapt ignition timing based on engine operating conditions and fuel properties by the mid-1990s microprocessor-based electronic fuel injection became a standard of the automotive industry these systems came in a myriad of configurations from simple single injector throttle body injection systems all the way to sophisticated two-stage sequential multi-port injection systems found on high performance engines the ECS that drove them also became more complex and capable as embedded microprocessors rapidly evolved engine management systems were now tasked with operating variable camshaft timing and duration mechanisms forced induction variable length intake tracks throttle by wire and various Emissions Control devices their tight integration into Vehicles would also make them an important diagnostic tool and by the second half of the 1990s they even functioned as an emissions regulatory device the fuel injector itself had now become a minor component of fuel injection by the late 1990s the centriole concept of directly injecting gasoline into a combustion chamber would merge with the recent introduction of high performance 32-bit embedded microprocessor-based engine management systems to produce the next Milestone of fuel injection development electronic gasoline direct injection first introduced in 1996 on the Japanese Market Mitsubishi Galant modern gasoline direct injection or GDI Works in a manner similar to its common rail Diesel Injection counterpart where a relatively low pressure fuel supply that is pumped electrically is mechanically pressurized to up to 350 bar or about 5000 PSI these high pressure pumps are generally camshaft driven plunger mechanisms that regulate fuel pressure with an ecu-controlled solenoid bypass valve the high pressure fuel is then fed to a common rail where it supplies an ecu-controlled injector that sprays directly into the combustion chamber unlike direct fuel injection of the past modern GDI systems use a precisely metered spray of fuel that is accurately timed to exploit its flow characteristics as it enters the combustion chamber the swirl pattern of the injected fuel is tightly controlled by the injector's placement fuel injection timing and by the geometry of the Piston's top face the structure of how fuel is distributed throughout the combustion chamber can be categorized into two charge modes homogeneous and stratified in homogeneous charging air and fuel is mixed uniformly within the cylinder with the goal of achieving a mixture ratio near ideal in order to increase the mixing time with incoming air fuel is injected towards the beginning of the intake stroke because of the mixing characteristics of the higher fuel pressure combined with the induced swirl homogeneous direct fuel injection is capable of producing more power overall when compared to manifold fuel injection permitting the use of smaller engines fuel efficiency is also slightly increased as comparatively less fuel enrichment is needed under certain engine conditions additionally homogeneous charging retains compatibility with existing catalytic converters due to its near stoichiometric operation stratified charging by comparison produces a unique fuel mixing condition within the combustion chamber that cannot be produced by manifold injection the induced fuel swirl pattern in this mode produces a small zone of air fuel mixture localized around the spark plug that is encapsulated by the surrounding air within the cylinder though this forms an ultra lean mixture across the entire cylinder the swirl cavity of air fuel is close to stoichiometrically Ideal and can be safely ignited this technique permits overall air fuel mixtures as high as 80 to 1 allowing for unmatched fuel efficiency at low to medium engine loads furthermore because the flame front is predominantly contained by air more heat is retained as it expands increasing the overall torque produced stratified charging also allows engine torque to be partially throttled by the combustion chamber fuel supply in a manner similar to a diesel engine this allows the throttle to remain open as much as possible reducing pumping losses in general one of three techniques are employed in order to shape the distribution of fuel within the combustion chamber in wall-guided direct injection fuel is sprayed against a swirl cavity on the top of the Piston which channels fuel towards the spark plug fuel mixing is aided by a high tumble intake Port design this technique is highly reliant on precise injection and ignition timing and also suffers from incomplete combustion issues at low to medium engine load due to the relatively cooler piston surface the fuel contacts another less popular technique is known as air guided direct injection this technique relies completely on intake air swirled to guide the injected fuel because the intake charge must maintain its swirl characteristics for a relatively long duration this technique compromises charging efficiency and ultimately power output often a hybrid model of wall-guided and air-guided direct injection is used to compensate for the deficiencies of both techniques the most popular of these three techniques is known as spray guided direct injection in this method fuel is injected directly at the spark plug at later stages of the compression stroke forming a tightly controlled stratification fuel gradient because ignition takes place immediately after injection and at a precisely determined location within the fuel gradient engine efficiency is increased however this technique requires tight manufacturing tolerances as this efficiency quickly breaks down as components come out of alignment Additionally the spark plug must be capable of tolerating heat shock caused by cooling from Fuel and the subsequent ignition event because the timing and flow characteristics of GDI injectors are critical to fuel swirl formation the method of their control is vastly different from manifold injection due to the high pressures involved they cycle rapidly with pulse widths lasting no more than a few milliseconds this requires a technique known as Peak and hold where the injector is quickly opened with a relatively high peak voltage that produces a high current Surge from there the injector is held open by subsequent steps of lower Drive currents until the spray duration ends in some contemporary designs the electromechanical solenoid has been replaced by a stack of piezoelectric material because piezoelectric injectors operate with just one tenth of a millimeter of valve motion they offer faster more accurate control when compared to solenoid injectors they can also be opened partially and the actuation speed of the technology also permits multiple injections during a single combustion cycle opening new design possibilities for GDI throughout the 2000s GDI technology began to expand rapidly within the automotive industry by 2018 GDI had seen the highest level of adoption of any emerging efficiency technology reaching 51 percent of new vehicles manufactured they're pairing with turbocharged smaller displacement engines in particular has grown in popularity over the last decade however despite the unprecedented level of fuel control GDI offers the technology still suffers from several notable disadvantages because no fuel is flowed over intake valves and GDI engines there is a lack of fuel cleaning action leading to an increase in carbon deposits GDI engines also struggle with producing Peak power at high engine RPM due to the limited window for introducing fuel to air some manufacturers have addressed both issues by the use of a two-stage system that employs both direct injection for fuel efficiency and manifold injection for Peak power and cleaning action while GDI engines produce significantly less CO2 emissions the use of ultra lean stratified charging suffers from excessive nitrogen oxide production and higher levels of black carbon aerosols than traditional fuel injection this combined with the relatively low gains in efficiency had led several manufacturers to abandon the concept other noteworthy disadvantages include injector wear due to the high operating pressures involved and lack of suitable lubrication and the need for more complex diagnostic procedures in their service despite the expeditious nature of the adoption of electric vehicles in recent years the automotive industry anticipates that more than 80 percent of light duty Vehicles sold in 2030 are still expected to have an internal combustion engine with most of these engines being gasoline powered it's anticipated that the fuel injection technology Market will grow by over 30 percent in both the US and EU over the next five to ten years still with the shift towards electronic Vehicles underway it's quite likely that the current state of fuel injection technology may prove to be the final evolution of a century and a half long pursuit of mixing fuel with air to extract work from combustion

Channel: New Mind

Views: 1,374,397

Keywords: fuel injector, injector bump, distribution pump, jerk pump, diesel fuel injection, injector nozzle, pintle injector, air blast injector, common rail injector, unit injector, direct gasoline injection, fuel rail, mechanical injection, bosch, mistubishi, Rochester ramjet, constant flow fuel injection, mechanical fuel pump, fuel pump, how fuel injection works, air injector, air blast, solenoid injector, gear pump, spur gear pump, manifold injection, direct injection, gdi, ecu

Id: N0RIGWUnVFc

Length: 39min 0sec (2340 seconds)

Published: Wed Nov 23 2022