The behaviour of tooth mesh frequency sound radiated from a tooth mesh point of a spur gear pair was investigated to see how it is generated. after examining the effect of bottom clearance, torque ...and material (steel or nylon) upon the radiation, the sound proved to be an aerodynamic sound; i.e., the sound is born from the pumping action of the clearance between meshing teeth, under high speed conditions. Especially towards the exit side of meshing, the radiation is prominent, with a "level trough" feature, which occurs due to the existence of two sorts of sounds having a phase difference of 180° near the meshing point. It has also become clear that this aerodynamic sound can not necessarily be reduced by increasing the clearance, after a consideration based on an analogy to the fluctuation of the flow rate of a gear pump.
By allowing for a small amount o gearing errors, the authors established a new design method of internal gear pumps with an appreciably larger specific-delivery than that of the internal trochoid ...pumps, etc. Using this method, three kinds of internal gear pumps with numbers of teeth z1 = 8 and z2 = 11 and also with z1 = 7 and z2 = 10 were designed and made in the author's laboratory. The performance of the trial-made gear pumps was as good as supposed, and almost the same as that estimated from the theory. Endurance tests were conducted using one of the trial-made gear pumps because there was a possibility of tooth surface failure due to excessive contact stress between the meshing teeth. However, no failure occurred at all when the gear pump was operated at a delivery pressure of 1.0 MPa (≒ 10 kgf/cm2) for 5×106 revolutions.
This paper presents characteristics of discharge pulsating pressure generated by an external gear pump. Based on the theoretical and experimental examinations, it is pointed out first that the former ...mathematical model for flow ripple is insufficient in the case of high working pressure or low pump speed. It is found experimentally that a large amount of leakage through relief grooves takes place intermittently in the vicinity of the central position of trapping. This leakage affects dominantly the fluctuation of a discharge flow (flow ripple), especially its higher harmonic components. The calculated values of discharge pressure pulsations based on the presentmathematical model for flow ripple taking the leakage mentioned above into consideration agree well up to about tenth harmonic with the experimental values.
The paper presents in an applicative manner a parameter-based methodology about design, modeling and optimization of a spur gear pump, currently under production in a Romanian company. Wanting to ...expand their product range, the company asked for a parameter-based design of this type of pump, FEM simulations and optimization of its conception to cover a wider range of flow rates, as required by current beneficiaries. The purpose of this research was to find improved alternative solutions via parametric design, mathematical validation and finite element simulation of the manufacturing solutions. The pump model is well known and has been manufactured for decades in many countries, under various licenses and constructive variants. The research process analyzed the functional role of the gear pump, its structure, its 3D model, which was reconstructed from the last manufactured solution, while identifying certain dimensions to be optimized and used in parametric design relations. The author used the CATIA V5 software and Visual Basic programing language. By mathematical computation, there were identified the pressure values and forces generated in the pump’s gears, applied later in FEM simulations to check the behavior of the pump components at the loads generated by these forces and pressures. The paper identifies and presents in a summary table the maximum stress values, deformations and percentages of computation errors for each pump’s constructive solution.
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