Abstract
The improvement of the overall performance of hydraulic pumps is the basis of intelligent hydraulics. Taking the straight line conjugate internal meshing gear pump as the research object, the theoretical flow rate and the geometric flow pulsation rate equations are established in this study through the volume change method. The change laws of the gear pair’s geometric parameters on the theoretical flow rate and the geometric flow pulsation rate are studied. The simulation model of the internal flow channel is established, and the influence factors and the influence degree of the flow pulsation and average flow rate are analyzed. The high-pressure positive displacement pump test system is also designed and built. The performance evaluations are conducted, and the experimental results are analyzed. The results show that the periodic change of the meshing point position is the root cause of the geometric flow pulsation. The theoretical flow rate and the geometric flow pulsation rate are 103.71 L/min and 1.76%, respectively. To increase the theoretical flow rate whilst decreasing the geometric flow pulsation rate, the tip circle radius of the external gear should be increased as much as possible within the allowable range of the design calculation. Amongst the three influencing factors that produce flow pulsation, the oil compressibility has no effect on the flow pulsation. The uneven internal leakage is the main factor, and the geometric flow pulsation only accounts for a small proportion. The internal leakage reduces the simulated flow rate by 3.59 L/min. The difference between the experimental and simulated flow rates is less than 2%. Within the allowable speed range, the rotation speed of the external gear should be increased as much as possible to increase the average flow rate and the volumetric efficiency.
Highlights
With the continuous development of hydraulic technology, digital and intelligent hydraulics have become hotspots in the industry
The core components include an external gear with a straight tooth profile
The corresponding constraint conditions include the limitation of the tooth thickness in the gear tip circle, the continuous transmission condition of gear pair, the limitation of meshing limit point, the limitation of tooth profile overlap interference, etc
Summary
With the continuous development of hydraulic technology, digital and intelligent hydraulics have become hotspots in the industry. The advancement of the body part and the improvement of the hydraulic pump’s overall performance (e.g., high pressure, low noise, low pulsation, and large and variable displacements) are an objective of intelligent hydraulics [1,2,3,4,5]. These flow characteristics should be accurately determined for the research and development of high-performance gear pumps. Its internal ring gear has a high-order circular tooth profile and is conjugate to the straight tooth profile of the external gear. Given unfavourable factors such as the technical protection of foreign companies, open and complete standardised design systems are scarce. Few studies on the performance of the entire pump have been published
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