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by Hi Tech Diesel Injection | Mar 8, 2017 | Fuel Injections Parts
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.
At the heart of a piezo injector is the piezoelectric (piezo) crystal. It rapidly expands when electricity is applied, making it suitable to act as the actuator in a diesel fuel injector. 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.
High pressure fuel is delivered to the tip of the injector where a needle rests and blocks fuel from being injected. Pressurized fuel is also delivered to the top of this needle, the force of which keeps the needle closed.
Piezo electric fuel injector process diagram (via Diesel Hub)
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. With no pressure at the top of the needle, it springs open, allowing fuel to be injected into the combustion chamber. When the Piezo actuator is de-energized, the valve closes and high pressure fuel forces the needle to return to the closed position.
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.