![]() Moreover, electrical faults lead to deactivation of cylinder balancing and limited anti slip regulation (no intervention in engine management). resulting from cut-off of the pilot injection) If the wiring harness connector is detached at the moment of injection, this leads to continuous injection and engine damage.As the injection is ended by means of the discharging current, the wiring harness connector of the piezo fuel injectors must on no account be detached when the engine is running. ![]() The discharging current causes the piezo actuator to return to its initial position and injection ends. To reverse the expansion of the piezo actuator, a short burst of current in the opposite direction (discharging current) is generated. 140 V is maintained by the PCM by means of a capacitor. ![]() During the injection phase, a voltage of approx. In order to operate the piezo actuator, a brief burst of current (charging current) is needed. In the case of vehicles with diesel particulate filters, any possible post-injections following the main injections during the regeneration process are comparable to the pilot injections. The various characteristic curves during pilot injection and main injection are shown in the illustration. 0.2 milliseconds.įuel injector actuation characteristic curveĪ Injected fuel quantity for pilot injectionī Injected fuel quantity for main injection The discharging time of the piezo actuator and consequently the closing time of the fuel injector needle is approx. In order to end the injection process, a further voltage impulse is required from the PCM. During the charging phase, the piezo actuator expands (elastic tension) and opens the fuel injector needle. The voltage pulse causes the individual peizoelements to press against one another, generating further voltage. 140 V within 0.2 milliseconds by the piezoelement. ![]() The initial charging voltage applied by the PCM for opening the fuel injectors is 70 V, however, this is increased to approx. A voltage pulse is required both for opening and closing the fuel injectors. The piezo-electrically controlled fuel injectors switch up to four times more rapidly than electro-magnetically actuated fuel injectors.Īctuation of the fuel injectors for fuel metering (start of injection and injected fuel quantity) is performed directly by the PCM, whereby the target rail pressure must be at least 150 bar during startup. B Voltage pulse from the PCM: Start of charging phase, fuel injector begins to openĭ Voltage pulse from the PCM: Start of discharging phase, injection ends ![]()
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