Abstract
In this paper the main performance parameters of an innovative high-speed external gear pump have been measured and analyzed for verifying its potential use as a reliable and efficient power unit for advanced electro-hydraulic actuated, automotive transmissions. More in detail, in order to deal with extremely challenging operating conditions, mainly in terms of rotational speed and delivery pressure, this volumetric machine is equipped with both two suction and delivery ports.
Firstly, the most important hydraulic and mechanical performance parameters have been acquired and evaluated, over a wide range of rotational speeds, spanning between 500 and 7000 rpm, and for two different operating temperatures, respectively equal to 40 and 60 °C.
With the aim to demonstrate the consistency of the implemented experimental procedure, two external gear pump prototypes, with the same design geometrical features, have been tested and compared, also with equivalent measurements provided by the pump manufacturer.
All the experimental tests have been completed with the help of a custom-tailored test bench, equipped with a double Cardan joint and an overdrive, specifically designed for running the pump at high rotational speed and applying a delivery pressure of about 45 bar, very near to a typical actuation value of a modern high-performance automotive transmission.
Finally, an interesting hydraulic layout, where a fraction of the overall volumetric flow rate delivered by the pump is recirculated through the secondary suction port, has been tested and compared with the standard setup where both the suction ports are directly connected to an atmospheric pressure tank. The main performance parameters measured for the two cases are very similar and, thus, the recirculating configuration can be considered as a very promising design solution for the entire actuation system.
At the end of this thorough experimental study, it is possible to conclude that the high-speed external gear pump prototypes tested and analyzed can be considered a reliable and effective alternative hydraulic power unit for advanced high-performance electro-hydraulic actuated automotive transmissions.
