Piezo injectors play a key part in developing modern engine combustion processes in the automotive industry. Permitting high-precision injection, they are also capable of operating at very high pressures. On top of this, piezo injectors are far lighter and respond more quickly than conventional solenoid injectors. Their greatest edge lies in them being able to realize partial needle lifts, something the principle behind solenoid valves is incapable of doing. This provides the basis for continuously shaping the rate of injection. The new piezo output stage for the FI2RE makes it possible to control as many as four injectors of this type, providing flexibility actuating injection in each cylinder. The user can also group up to three output stages that are then capable of controlling as many as twelve injectors. The output stage permits up to five injections per work cycle, such as three preinjections, a main injection and a postinjection. Featuring high-performance technology, the output stage actuates injectors more quickly and also controls the injected fuel quantity and course of injection with significantly greater flexibility. All of these benefits are important criteria in the context of providing efficient, smooth and low-emission combustion. This is where injectors work on a voltage of up to 200 V and currents ranging from -20 to +20 amps. Adjustments beyond these levels can be made on request.
The piezo output stage is an all-new development. Digitally clocked, it is significantly smaller and lighter than its analog predecessor, meaning it requires no special cooling system. The high voltage demanded for the piezo injectors is generated by a built-in power pack from the voltage supplied to the FI2RE. This simplifies handling in the vehicle and on the test bench.
Operation has been simplified too. A new oscilloscope function provided by the FI2RE commander provides the facility of observing voltage, charge, current and capacitance while the injector is being actuatedd. Calibration tools, such as INCA from ETAS and other applications, are capable of communicating with the piezo output stage using a CAN interface.
Internal control is handled by means of four real-time ASIPs (Application-Specific Instruction-Set Processor) developed specifically for the output stage. The ASIPs work independently of each other to ensure a high degree of flexibility and real-time performance. Also new to the system are two trigger outputs that users can configure themselves. These outputs can be employed, for instance, for triggering an external oscilloscope or camera in synchrony with time. The software can now also be updated by means of online firmware. Customer-specific adaptations are fast to implement since updates can simply be sent in electronic form.
The new piezo output stage is an extension of the FI2RE (Flexible Injection and Ignition for Rapid Engineering) development control unit that has been in service for some time now for a wide and diverse range of applications. FI2RE is capable of providing flexibility in activating all components in synchrony with crank angle and in relation to testing their behavior even before suitable control units are developed.
About IAV GmbH:
Employing over 3,000 members of staff across the globe, IAV (Ingenieurgesellschaft Auto und Verkehr) is one of the leading providers of engineering services to the automotive industry. The company has been developing innovative concepts and technologies for future vehicle generations for over 25 years. Core competencies include production-ready solutions in all fields of electronics, powertrain and vehicle development. Clients include all of the world's premier automobile manufacturers and suppliers. In addition to development centers in Berlin, Gifhorn and Chemnitz, IAV also operates from other locations in Europe, Asia as well as North and South America.
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