For the first time, the pipes with piezoelectric power have appeared in the design of the Common Rail Diesel engine system. In contrast to widely used solenoids, the new-generation nozzle is extremely fast. The use of piezoelectric nozzles allows for the injection of fuel repeatedly over the course of one cycle, at the expense of record speed. In the future, the principle was successfully applied in direct injection systems. History of piezoelectric nozzles
History of piezoelectric nozzles
The Common Rail gas storage system was developed in the middle of the ' 90s by the Japanese DENSO Corporation. It was initially planned to use the new injection technology on trucks, but it was so successful that DENSO has sold the production license to other manufacturers since 1995.
The discovery of the piezoeffect belongs to the French physicists the brothers Jacques and Pierre Curie
Robert Bosch GmbH played a major role in the improvement of the system. It has become a pioneer of adaptation of the system for gasoline engines.
In the system of direct injection of production of Robert Busch, the piezoelectric power train is used. A good example is the Mercedes-Benz M278 engine. In this eight-cylinder engine, which has been installed at Mercedes-Benz S-Class S500 since 2011, the use of piezoelectric nozzles has made it possible to achieve this economy, which in the United States has ceased to fall under the so-called "Gas Guzzler Tax", the law on which heavy motor vehicles are subject to an additional tax on the principle of increased fuel consumption. The actual volume of the S-Class S500 engine has not changed.
Principle of pyeelectro-electric trout
The control valve of the nozzle valve is based on the well-known piezoelectric effect, which is applied, for example, in the construction of gas lighters. A button that a person presses with a finger deforms a work item from a special material-dielectric. The deformation shall contribute to the charge that shall be used for the ignition of the gas.
In addition to fuel injectors, the piezoeffect is used in the detonation sensor and inlet absolute pressure transducer (MAP)
The piezoelectric nozzeces use the so-called inverse piezoelectric effect. A dielectrac is energyled to deformation the material. A valve dielectro is associated with a dielectric current when the valve is applied to the nozzle.
Advantages of piezoelectric nozzles
Injection phase management
The use of the pio-electric valve has increased the speed of the injectable with the electromagnetic valve (solenoid) almost four times. The most precise splitting of the injection phase was achieved by allowing a high response rate to contribute to the full opening and locking of the valve in a short time. The same characteristic allowed for high accuracy to change the duration of opening of the control valve of the nozzle.
Variable injection pressure
Frequently, with a post-injective injection that involves multiple opening of the nozzles, each phase requires not only varying durations, but also pressure. For the primary, the "ignition" phase, the pressure must be minimal, and a very high pressure is required to supply the working dose. The use of the piezoelectric trout made it possible to change the injection pressure within a wide range of approximately 130 to 2,200 bar.
Noise reduction in engine operation
The sound of the engine at idling is caused by sudden changes in the pressure of the fuel in the nozzle, as well as the vibrations resulting from the vibrations of the engine. The new nozzle speed, thanks to the speed of the piezovalve, makes it possible to significantly reduce the noise level. During the development of the piezoelectric trout, the diameter of the trout was reduced, which made it possible to reduce mechanical noise in its work.
Communist Party of the Soviet Party
The high efficiency of the injector pump is due to the reduction in the electrical power required for the valve operation. By reducing the amount of fuel necessary for the injection, the diameter of the nozzle of the injector was 6.35 mm without losing the intensity of its delivery.
Design considerations for piezoelectric trout
Fish Multiplier
The feature of the piez-drive is that its work element is compressed by only 0.04 mm, and a minimum of 0.1 mm is required to fully open the needle of the valve. To solve this problem, between a valve needle and a piezodrive, a chivalricator, having the desired transmission ratio, is mounted. At the time the voltage is applied, the multiplier is actuated from the pressure plate while ensuring the movement of the needle by 0.1 mm.
spring trout
The spring is an important part of the piezoelectric trout. A specially provided cavity contains a spring that controls the landing of a sprayer needle in the saddle. Pruzhin carries out another responsible function-it prevents the opening of the nozzle at the injection of fuel in the very first phase (at the end of the compression cycle). The principle of post injection for different phases requires different pressure on the valve needle.
Non-return valve
The end of each injection phase is accompanied by the disposal of unused excess fuel. A throttle was fitted with a non-return valve on the discharge. If the flow of the fuel is waning, the pressure before the throttle shall be reduced. The non-return valve shall be closed to maintain the position of the needle for the next injection phase.
Specific features of piezoelectric trout
The use of such a precision mechanism as a piezoelectric trout allows for vertices of speed. For the same reason, the fuel used in the car should not be even the smallest impurities. When dirt is hit, the noonkers get out of formation almost instant-instantly. The cost of piezoelectric nozzles varies from 10 to 15 thousand rubles, while the repair will cost about half of this amount.
