The Fuel Injector Story - Part 1

this episode is brought to you by curiositystream 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 in 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 george bailey brayton had patented a unique internal combustion engine design known as the constant pressure internal combustion engine known as brayton'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 gas is 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-resting wire mesh where it's ignited by a constant burning pilot flame the combusting and expanding gases generated around 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 engine suffered from a fatal flaw if the flame arresting mesh failed the ignition source could run back into the reservoir of the air fuel mixture leading to an explosion to counter this hazard brayton 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 brayton 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 britain'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 fuel 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 feynes 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 rail 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 of the feel 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 fuel 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 pressures between 200 to 340 bar or about 3000 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 pintle 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 pintle 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 wiedman 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 carburetion 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 levassour's 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 in lava vasor's 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 kinsei and kasi radial aircraft engines with the technology the right cyclone series engines and later versions of the rolls-royce merlin engines were 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 messerschmitt bf109e this system would make its debut on the two-stroke engines of the guproad 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 300sl and the w196 grand prix car mercedes victories at le mans mill 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 core event 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 bulb 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 a far simpler and cheaper to manufacture spur gear pump it also incorporated features that improved drivability such as coal stock 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 80 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 compliant 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 and fuel quantity in part two we'll look at how the emergence of the transistor and the electronics industry converging with policy changes and a failed research and development initiative that was decades ahead of its time would lead to one of the most groundbreaking changes within the automotive industry the introduction of electronic fuel injection one of my favorite topics to explore is how technology developed in the motorsports world migrates to everyday vehicles in fact i highly recommend the documentary i found on curiosity stream called how to build a supercar it dives into mclaren's re-entry into the production car market and how they carried over technologies and manufacturing secrets from their formula one program into their first modern road car the mp412c in 2011. curiosity stream is an online streaming service with an incredible library of thousands of documentaries and non-fiction titles from some of the best filmmakers in the game their huge catalog offers titles covering a broad range of topics like history nature science food technology and travel as well as several award-winning exclusives and originals they even feature 35 collections of curated programs hand-picked by their experts each perfectly tailored to a topic of interest and right now if you use the code new mind to sign up curiosity stream is available for just 14.99 for the whole year curiosity stream is available on just about any platform you can imagine including smart tvs so wherever you are you will always have access to great interesting content check out curiositystream with the link in the description below or go to curiositystream.com front slash new mind you

Channel: New Mind

Views: 172,917

Rating: 4.9203219 out of 5

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, fuel map, mechanical fuel pump, fuel pump, how fuel injection works, air injector, air blast, delphi, solenoid injector, gear pump, spur gear pump, manifold injection

Id: rrXsATzAFto

Length: 17min 22sec (1042 seconds)

Published: Tue Apr 13 2021