Scientific and technical journal

«Equipment and technologies for oil and gas complex»

ISSN 1999-6934

Equipment and technologies for oil and gas complex

UDC: 621.665:622.24
DOI: 10.33285/1999-6934-2021-6(126)-22-26



1 National University of Oil and Gas "Gubkin University", Moscow, Russian Federation

Keywords: positive displacement motor, cycloidal gearing, face profile, wide-line profiling, working part, useful area, optimization of geometric parameters, numerical method


One of the trends of improving positive displacement motors (PDM), used for drilling oil and gas wells and increasing their operational showings is optimization of the geometric parameters of the cycloidal gearing of motor’s working parts. The article considers the influence of evolution of the cycloidal face profile on the geometric and kinematic parameters of the PDM and offers a generalized table of the effect of dimensionless coefficients on the cycloidal gearing characteristics, which allows optimization of the profile based on geometric and kinematic criteria generalized in the objective function. The analysis of the evolution of the cycloidal profile shape showed that, if it is necessary to modify the power section due to varying by the dimensionless geometric coefficients (while maintaining the smoothness of the contours), the useful area can be changed in a wide range, and the maximum value of the area refers to the cycloidal gearing with the minimum numerical values of the geometric coefficients. This allows a more reasonable approach to the cycloidal profile design and selection of its optimal parameters for various types of drill bits and diametrical dimensions of the motor. The proposed methodology can also be used when designing the end profile of gerotor hydraulic machines.


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