Optimization of a Sliding Rotary Vane Pump for Heavy Duty Internal Combustion Engine cooling 2024-37-0030

The benefits introduced by the replacement of conventional centrifugal pumps with volumetric machines for Internal Combustion Engines (ICEs) cooling were experimentally and theoretically proven in literature. In particular, Sliding Rotary Vane Pumps (SVRPs) ensure to achieve an interesting reduction of ICEs fuel consumption and CO2 emissions. Despite volumetric pumps are a reference technology for ICE lubrication oil circuits, the application in ICE cooling systems still not represent a ready-to-market solution. Particularly challenging is the case of Heavy-Duty ICE due to the wide operating range the pump covers in terms of flow rate delivered. Generally, SVRPs are designed to operate at high speeds to reduce machine dimensions and, consequently, the weight. Nevertheless, speed increase could lead to a severe penalization of pump performance since the growth of the friction losses. They produce wear phenomena which require expensive surface treatments or, more generally, the adoption of materials which resist to higher mechanical stresses. Authors in their previous works developed an alternative design strategy based on the speed reduction compensating the size increase with an increase of the volumetric capability. It was found thanks to a peculiar property of SVRPs, an optimized variation of machine eccentricity leads to a higher volume capability, with a negligible increase of machine dimensions. In this way, the operating speed could be reduced avoiding the increase of machine size. A Low-Speed (LS) SVRP prototype was hence built, and the benefit introduced by the proposed design strategy was experimentally demonstrated in previous works after a theoretical model-based design. A further increase of performances was presented in this paper. The subject of interest was found on the intake and exhaust ports optimization which enhance vane filling and emptying, improving the volumetric capacity of the machine and decreasing the “passive” volume which is recirculated inside the pump decreasing volumetric and indicated efficiency. Non-conventional solutions were found to gain the fluid dynamic performances of ports. The cavitation phenomenon was also included having observed from preliminary testing the occurrence of it on stator casing in similar applications. Machine shaping was also optimized in terms of diameter/length ratio, considering that the two geometrical parameters can influence in opposite directions volumetric, indicated, and mechanical efficiencies. A trade-off between these performances exists if the goal is the overall efficiency optimization. Hence, thanks to an updated more comprehensive modelling, an optimized model-based design was produced in this work. Finally, the optimized SVRP was compared with the conventional centrifugal pump operating on the reference ICE (CURSOR 13 NG) over a WHTC (World Harmonized Transient Cycle) to quantify the benefits offered in terms of ICE fuel saving and CO2 emission reduction.