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Electrical Oil Pump (e-OP): Layout Definition and Design Validation through the 3D Thermal Simulation Approach

Giorgio Peroni, Alessandro Malvasi, Raffaele Squarcini
Pierburg Pump Technology Italy

During last years, new concepts of oil pumps for automotive applications have become matter of accurate study for international producers like Pierburg Pump Technology, due to the increasingly demanding requirements for lowering the power consumption. As a result, new products have been developed and introduced into the market: electric oil pump (e-OP) is one of the most innovative.
This consists of a traditional pumping gear unit driven by a dedicated electric motor and controlled by an electronics module: based on the customer’s specifications, the rotating speed of the pump can be changed by the control unit according to the different working conditions. This allows adapting the oil supply to the actual needs of the circuit. An essential phase of the engineering process of such a product is the thermal management: the functionality of the electronic module has to be assured under the thermal loads generated by the combination of current, oil and environment; moreover, the temperature of the plastic components should be minimized for structural reasons as well as the motor cannot exceed given temperature values. To this aim, two features play a key role: an appropriate choice of the overall pump’s layout and a suitable choice of the components’ materials.
To support these decisions the simulation approach has been heavily employed during the pre-design phase of the new generation of e-OPs due to the consequent benefit in terms of time and cost saving; thus, a specific methodology to predict the temperature field of the pump has been developed by the means of the three-dimensional thermal analysis with CFD. This provides higher accuracy in comparison to the traditional zero- or mono-dimensional approaches, being sensitive to the spatial arrangement of the heat sources as respects to the cool spots of the pump and considering such complex heat exchange surfaces. Anyway, the drawback of the higher effort in terms of model setup has been faced employing dummy models aimed to the layout evaluations so as to simplify the complete model with specific assumptions. Finally the test measurements performed on the actual pump have shown a good agreement with the results from the complete model: this confirms that the calculation assumptions are correct providing also some useful indications for the future enhancements of the methodology.