An Investigation of the Impact of Pump Deformations on Circumferential Gap Height as a Factor Influencing Volumetric Efficiency of External Gear Pumps

Abstract

Gear pumps are widely used in transport machines not only in hydraulic drive systems, but also in lubrication and fuel systems. A positive displacement pump converts mechanical energy into pressure energy stored in the liquid, which it transports to the hydraulic cylinder or motor. The efficiency of this process depends on the efficiency of the system components, including the efficiency of the pump, which depends on the amount of internal leakage through the gaps between the high and low pressure sides. The larger the gaps, the lower the volumetric efficiency. This article presents an investigations of impact of pump deformations on circumferential gap height. The article presents a three-dimensional model of an external gear pump using Finite Element Method (FEM) during operating conditions. The model reflects pumping operation at discharge pressures up to 32 MPa and it was validated against strain measurements of pump casing. The simulation results indicate that the pump casing becomes deformed due to pressure, causing a significant increase in the height of the circumferential gap. The increase of the discharge pressure from 8 to 32 MPa causes more than twofold local increase in the height of the circumferential gap. The obtained results indicate that for the correct modelling of the flow generated by gear pumps, it is necessary to consider the change in the size of the gaps resulting from the deformation of the pump.

Influence of the Hydraulic Circuit Setup on the Dynamic Performance of an Axial Piston Pump by Numerical and Experimental Analysis

“…There are other research works in the literature discussing simulations and modeling of this type of gear (e.g., [12,13]). Finite element analysis is frequently used in strength calculation of pumps, and the study of Cieślicki and Karpenko [14] is one example of the recent studies that used this approach. Finite element analysis is also performed to study the vibratory performance of peristaltic pumps [15,16].…”

Improving the Design of a Multi-Gear Pump Switchgear Using CFD Analysis

“…Gear pumps belong to a separate group of positive displacement pumps [1,2]. The suction and injection of the working fluid into the hydraulic system from the gear pump are provided due to the variable volume in the low-and high-pressure cavities caused by the entrance and exit of the teeth of the meshing during their rotation [3,4].…”

Numerical Investigation on Pairing Solutions of Non-Positive Displacement Pumps and Internal Gear Pump for High-Speed Design

“…There are many reasons for the reduction of the effective oil delivery of a hydraulic pump. Rafał and Mykola demonstrated the pump deformations on circumferential gap height as a factor influencing volumetric efficiency [8]. Therefore, regardless of high-speed or high-pressure conditions, if low-viscosity liquids were to be used, the axial and radial clearances between the gear pair and the housing should be reduced to avoid large internal leakage [9].…”