Lubrication pumps for internal combustion engines: a review

The paper presents the evolution of the lubrication pumps for internal combustion engines in the last two decades. After the description of the traditional fixed displacement gear units, the interaction with the circuit is evaluated to determine their operating points. The analysis brings to evidence a mismatch in terms of flow rate and pressure between the engine requirements and the pump characteristic. Such difference has a negative effect on the overall efficiency of the flow-generating unit, leading to a significant waste of fuel. For this reason, several innovations aimed at reducing the power absorbed by the lubrication pump have been developed in recent years. The solutions presented in this paper range from variable displacement to variable timing to electric pumps. Moreover, different methods for controlling the circuit pressure, such as thermostatic and electrical devices, discrete and continuous, are also discussed. From this extensive analysis, it is evident that the most recent innovations can lead to a reduction of the fuel consumption from 2 to 4%.