![]() ![]() Internal mixture formation systems can be separated into direct and indirect injection systems. There exist two types of manifold injection systems: multi-point injection (or port injection) and single-point injection (or throttle body injection). A fuel injection system that uses external mixture formation is called a manifold injection system. There are two main functional principles of mixture formation systems for internal combustion engines: internal mixture formation, and external mixture formation. Typically, the only thing all fuel injection systems have in common is a lack of carburetion. ![]() The term "fuel injection" is vague and comprises various distinct systems with fundamentally different functional principles. The primary difference between carburetion and fuel injection is that fuel injection atomizes the fuel through a small nozzle under high pressure, while a carburettor relies on suction created by intake air accelerated through a Venturi tube to draw fuel into the airstream. In passenger car petrol engines, fuel injection was introduced in the early 1950s and gradually gained prevalence until it had largely replaced carburettors by the early 1990s. Mass-produced diesel engines for passenger cars (such as the Mercedes-Benz OM 138) became available in the late 1930s and early 1940s, being the first fuel-injected engines for passenger car use. petrol (gasoline) engines, such as Otto or Wankel), use fuel injection of one kind or another. diesel engines), and many spark-ignition engines (i.e. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines.Īll compression-ignition engines (e.g. The injection process occurs extremely fast and because the actuator can be activated and deactivated so quickly, piezo injectors are known for their superior reliability, increased durability, efficiency and reduced emissions.A cutaway model of a petrol direct-injected engineįuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. When the Piezo actuator is de-energized, the valve closes and high pressure fuel forces the needle to return to the closed position. With no pressure at the top of the needle, it springs open, allowing fuel to be injected into the combustion chamber. When the Piezo crystal is energized, a valve at the top of the needle opens, allowing the pressurized fuel at the top of the needle to return to the tank through the return line. Piezo electric fuel injector process diagram (via Diesel Hub) Pressurized fuel is also delivered to the top of this needle, the force of which keeps the needle closed. High pressure fuel is delivered to the tip of the injector where a needle rests and blocks fuel from being injected. A piezo injector can act up to five times faster than a standard injector solenoid and the motion is frictionless, which allows for precise fuel measurement and multiple injector events per combustion cycle. It rapidly expands when electricity is applied, making it suitable to act as the actuator in a diesel fuel injector. Piezo injectors are crucial in modern common rail diesel engines, instigating a rapid series of injection events which allow for greater efficiency, performance & reduced emissions.Īt the heart of a piezo injector is the piezoelectric (piezo) crystal. ![]()
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