Analysis of Stress and Deformation in Plastic Gears Used in Gerotor Pumps

Abstract

The mechanism of induction of stresses and deformations in plastic cycloidal gears used in gerotor pumps has been analysed using the finite element method and the ABAQUS program. It has been found that the gear system remains under the influence of the mechanical load resulting from the torque on the pump shaft and the hydraulic load resulting from the activity of pressure in the intertooth displacement chambers. It has also been discovered that the intertooth forces and stresses are formed only in the part of the gear that can be referred to as 'active'. In the other part of the gear, forces and stresses do not occur, and the part can be referred to as 'passive'. Another finding of the research is that gear deformations occur such that the teeth of the external gear are deformed and moved in the direction of the active part of the mesh, and the teeth of the internal gear in the direction of the passive part. Thus, radial and axial intertooth clearances are formed, which result in internal leakages in the pump, as well as in lower working pressure and efficiency of the machine. A way of determining the load range for plastic gears used in gerotor pumps has been specified. It has also been observed that the loading of the pump should not result in reduced stresses s z higher than compressive stresses s c equal to the plasticity limit Re of the plastic, that is, s z ( s c 5 Re. At the same time, the radial clearance h r and the axial clearance h a should not exceed the extreme values h r max and h a max assumed for a particular size of gerotor pump, that is, h r , h r max and h a , h a max .

Analysis of the material and design modifications influence on strength of the cycloidal gear system

“…The maximum value of the clearance was defined as the allowable radial clearance value hr prm =0.1mm. 25 Value For the cycloidal gear system depicted in Fig. 2b, the maximum deformation was observed at the top of tooth 4' and radial clearance h r generated by the deformation was h r =0.082mm.…”

“…In this area keyways are made, and also there is a contact with the shaft. According to the previous analyses 25,29,30 around the keyways high stress values are recorded. It is also to see in Fig.…”

“…In the papers 25,29,30 results of the theoretical and practical research on the gerotor pump featuring a polyoxymethylene (POM) gear system have been presented. It enabled the practical verification of the strength models for the cycloidal gears made of polyoxymethylene, which had been described in the previous work.…”

“…It enabled the practical verification of the strength models for the cycloidal gears made of polyoxymethylene, which had been described in the previous work. 25,29 The practical research showed that a gerotor pump with such gears can work up to the value of working pressure p=6MPa. 30 In order to take the next step in the development of the gerotor machines, it is necessary to present design solutions for the cycloidal gears made of plastics, which will enable their operation at higher values of working pressure p. The solutions ought to be focused both on the material modifications and on the changes in the gear design Therefore, it is necessary to introduce modifications in the cycloidal gears' design in order to widen the range of operational parameters for the gears.…”

Effect of load and speed on warship power rear drive system helical gear anti-scuffing properties in thermal elasto-hydrodynamic lubrication

“…It usually occurs in a short time and could sometimes damage gear surface. [1][2][3] To date, a great deal of studies 4 have been done to study teeth cracking and pitting due to scoring. Some empirical equations and criteria 5 were thereafter presented.…”