Magneti Marelli is an international group that develops and produces high-tech components and systems for the automotive sector. With more than 38,000 employees, 89 production units, 12 research and development (R&D) centers and 26 application centers, the group is located in 19 countries. Magneti Marelli supplies major automakers in Europe, Asia, North and South America. Its business lines are automotive lighting, powertrain, electronic systems, suspension systems, exhaust systems, aftermarket parts and services, plastic components and motorsport.
The fuel injection system plays a key role in the reduction of vehicle fuel consumption and pollutant emissions. Gasoline and diesel direct injection engines require extremely reliable high-pressure injection systems for advanced combustion strategies and to improve the fuel atomization and air-fuel mixing processes.
Nevertheless, in these installations the rapid opening and closing of the injectors and pump flow rate may cause fuel pressure fluctuations. These fluctuations can cause inferior precision, irregular fuel injections between cylinders and relatively poor spray quality. For this reason, the injection system design must be supported by accurate computational models able to predict the actual injector flow and the whole fuel system behavior.
A worldwide automotive tier-one supplier, Magneti Marelli is providing its know-how and wide-ranging expertise in electronics through a process of ongoing innovation and environmental sustainability. The group wants to develop intelligent systems for active and passive vehicle safety, onboard comfort and powertrain technologies. In 2009, Magneti Marelli chose Simcenter Amesim™ software, part of the Simcenter portfolio from Siemens Digital Industries Software, to support the design process of its high-tech fuel injection components and systems for cars, motorbikes and light vehicles.
“Model-based systems engineering is the only possible approach to deal with the actual complexity of injection system design,” says Domenico Paolino, mechanical engineer at Magneti Marelli.
With Simcenter Amesim, Magneti Marelli precisely models multi-domain components of modern fuel injection systems in order to control the fuel pressure fluctuation, inject the exact amount of fuel into the combustion chamber and thus lower the fuel consumption and meet stringent emission regulations. Using Simcenter Amesim, engineers check the correct dimensions of the fuel system and the right positions for flow restrictors and dampers to enhance their effectiveness.
Recently, the company developed a new technology, Controlled Low-Pressure Pump Supply (COLPS), to optimize its previous fuel system which included a pressure regulating valve (PRV) and fuel metering valves (FMVs). The injection system rail simplification enabled Magneti Marelli to reduce production costs. With COLPS, the low-pressure pump is controlled with an electric motor, which allows better control and pressure variation optimization. Moreover, the low-pressure pump can generate the exact flow rate to meet the target rail pressure with possible energy savings and emissions reduction.
Even though the injection system design was greatly simplified, the new technology requires a much more sophisticated controls strategy. To address controls complexity, Magneti Marelli system engineers use Simcenter Amesim to support the controls and software design teams that need to receive indications on hydraulic components’ behavior. Co-simulation with Simcenter Amesim and the Simulink® environment enables the controls algorithm to communicate with a plant model at a fixed time step, as in a real engine control unit (ECU).
“This approach enables us to assess in parallel hydraulic components and software behavior, which would be extremely time-consuming if performed directly on the test bench,” says Paolino. “Dealing with the validated hydraulic components of Simcenter Amesim enables the optimization of the software structure from the first design step. Further advantages are those related to the simulation of possible mechanical failures and software malfunctions, which help us understand the effects on the system and thus give important information about all the diagnosis design.”
Magneti Marelli chose to develop its controls strategy with Simulink while using Simcenter Amesim to model the multidomain engine components. The two solvers are in communication, and inputs and outputs are exchanged between the two environments. The creation of a complete virtual system environment enables simulation of the system behavior, for both hydraulic components and software. Simcenter Amesim and Simulink work together to improve the reliability of the controls strategy.
“We were able to match the advantages of these two environments to build complete model-based software including a multidomain system built using Simcenter Amesim and controls model built using Simulink. It enables us to optimize the product and components design from the first stages,” says Paolino.
Using co-simulation, Magneti Marelli runs virtual tests that would be impossible to recreate in reality. Their goals are to analyze the response of driving commands, outlet pressure and fuel temperature, and to measure the pump flow rate as a function of various external factors. The simulation of possible mechanical failures and software malfunctions helps engineers to understand their effects on the system and thus gives relevant information for design optimization.
“Another really useful functionality of Simcenter Amesim is the possibility to simulate some conditions that are quite difficult to recreate in reality,” says Marco Parotto, mechanical engineer at Magneti Marelli. “The controls designer can use this information to more precisely build the controls strategy from the beginning of the design process. Performing all these verifications on the test bench would be extremely time- and cost-consuming. The co-simulation with Simcenter Amesim and Simulink enabled us to reduce controls validation effort by 50 percent. Consequently, the time on the test bench has been considerably reduced as well.” Moreover, these virtual tests are becoming more and more valuable for regulation authorities.
“We work closely with BSim Engineering, a Siemens Digital Industries Software partner in Italy,” says Parotto. “The high responsiveness of BSim Engineering specialists helps us streamline our model development process.”
It has become common in the automotive industry to provide not only real products, but also related simulation models. On the one hand, as a customer Magneti Marelli receives Simcenter Amesim simulation models from its suppliers; on the other hand, as a supplier, the company provides models to its customers. “Simcenter Amesim has become a standard language that allows you to communicate faster and easier with your customers and suppliers,” says Parotto.