![]() ![]() ![]() The original benefit of the piezo injector design was the very fast operation which was up to five times faster than the inductive injectors of the time.Īdvances however in inductive diesel injector technology have meant that both injector types can now provide similar performance and it's difficult to clearly pick a winner. It's this movement that is in turn used to actuate and open the injector to start fuel flowing. The principal of operation is that when voltage is applied to the crystal stack, it expands, albeit only very slightly. Part of the solution to this is the very high voltages and currents used to control the injectors.įor example it's common for peak voltages to exceed 100 volts and peak current to reach in excess of 10 amps.Ī piezo injector on the other hand uses a crystal stack inside the injector which is typically made from quartz. In a common rail diesel injector this presents some challenges however as a result of the incredibly high fuel pressures that the injectors are subject to, and the very fast response required from the injector. This is more relevant for those of you considering the fitment of a univeral standalone ECU rather than reflashing the factory fitted ECU.Īn inductive injector is similar in operation to a conventional low pressure gasoline port fuel injector, where a magnetic coil inside the injector is responsible for opening and closing the injector to control fuel flow. In particular it's important to know that the way piezo and inductive injectors are controlled by the ECU are very different. 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.- The fuel injectors used for common rail diesel engines are generally grouped into two methods of operation, piezo, or piezo electric, and inductive or solenoid.Īs a diesel engine tuner it's not strictly essential to have a deep understanding of the specifics of the injector construction and operation, however it's still useful to understand the basic concepts. 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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