Friction Torque Modelling and Efficiency Analysis of the Preloaded Inverted Planetary Roller Screw Mechanism

2017 ◽  
Author(s):  
Guan Qiao ◽  
Geng Liu ◽  
Shangjun Ma ◽  
Zhenghong Shi ◽  
Teik C. Lim
Keyword(s):  
Optimization Design ◽  
Sliding Friction ◽  
Helix Angle ◽  
Efficiency Analysis ◽  
Transmission Efficiency ◽  
Friction Torque ◽  
Operating Conditions ◽  
Design Parameters ◽  
Roller Screw ◽  
Screw Mechanism

The efficiency analytical model of the inverted planetary roller screw mechanism is formulated based on the friction torque calculation. Firstly, the friction torque model considering the load distribution of thread teeth is established including the components such as curvature friction torque, friction torque due to spinning sliding, pure sliding friction torque between rollers and carriers, friction torque generated by the viscosity of lubricant, and preload torque. Secondly, the contribution of the friction torque components and torque distribution on the roller thread teeth are investigated. Finally, efficiency analysis is conducted by discussing the influences of structure parameters of the inverted planetary roller screw mechanism and operating conditions. Computational results reveal that the total friction torque and efficiency are influenced by axial load, number of roller thread teeth, nut speed, contact angle, and helix angle of nut with different extents. This study provides an understanding of the relationship between friction torque, transmission efficiency, and system design parameters, which can be employed to enhance the inverted planetary roller screw mechanism optimization design.

scholarly journals Friction Torque Analysis of Planetary Roller Screw Mechanism in Roller Jamming

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Linjie Li ◽  
Yongling Fu ◽  
Shicheng Zheng ◽  
Jian Fu ◽  
Tianxiang Xia
Keyword(s):  
Transmission Efficiency ◽  
Friction Torque ◽  
Contact Theory ◽  
Distribution Model ◽  
Structural Failure ◽  
Roller Screw ◽  
Torque Analysis ◽  
Screw Mechanism ◽  
Actuation Systems ◽  
Electromechanical Actuation

The load distribution model of the planetary roller screw mechanism (PRSM) is established on the basis of Hertz contact theory. The objective is to obtain a friction torque model of the PRSM in roller jamming. An example is provided to calculate the friction torque of the PRSM in roller jamming. Thereafter, the transmission efficiency is calculated. A static structural analysis is performed using the finite element method to estimate the contact stress between the threads of the PRSM components. Computational results indirectly reveal that roller jamming exerts considerable influence on the friction torque of the PRSM. Results show that the friction torque of the planetary roller screw increases when the roller is jammed and the wear of the parts is accelerated. This condition leads to structural failure. The results of this study can serve as a foundation for electromechanical actuation systems, which can be useful in designing antijamming systems for safety-critical aircraft applications.

Dynamic Stiffness Model of Planetary Roller Screw Mechanism With Clearance, Geometry Errors and Rolling-Sliding Friction

2017 ◽  
Author(s):  
Shangjun Ma ◽  
Cheng Peng ◽  
Xiaofeng Li ◽  
Geng Liu
Keyword(s):  
Sliding Friction ◽  
Contact Stiffness ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Helix Angle ◽  
Calculation Model ◽  
Load Distributions ◽  
Roller Screw ◽  
Screw Diameter ◽  
Screw Mechanism

This paper applies the bond graph theory to construct a dynamic stiffness calculation model for the planetary roller screw mechanism with factors such as structural stiffness and contact stiffness of screw, clearances, geometry errors, rolling-sliding friction, and load distributions on the roller threads and a group of rollers under two installation modes. In addition to predicting how dynamic stiffness varies with the load frequency and load amplitude under two installation modes, how does it change with the structural parameters such as screw diameter, helix angle, contact angle and number of roller threads under two installation modes are also investigated. The results can provide theoretical basis for the design of planetary roller screw mechanism considering dynamic stiffness with the influences of clearances, geometry errors, friction and installation modes.

scholarly journals Influence of design parameters and operating conditions on performance indicators of magnetic fluid seals of electric motor shafts

Vestnik IGEU ◽  
2019 ◽  
pp. 40-47
Author(s):  
A.M. Vlasov ◽  
Yu.B. Kazakov ◽  
V.A. Poletaev
Keyword(s):  
Surface Roughness ◽  
Magnetic Fluid ◽  
Electric Motor ◽  
Performance Indicators ◽  
Rough Surfaces ◽  
Rotation Frequency ◽  
Friction Torque ◽  
Operating Conditions ◽  
Design Parameters ◽  
External Temperature

Magnetic fluid seals (MFS) are beginning to be used to seal rotating shafts in electric motors operating in conditions of high humidity, dust and pollution. Friction torque and heating are the most important operational indicators of MFS depending on the design parameters and operation conditions: rotation frequency, operation time, temperature and clearance (taking into account roughness and waviness). An urgent task is to study the influence of design parameters and operating conditions on the performance indicators of MFS of such electric motor shafts. The modeling of rough surfaces was performed using orthogonal transformations of roughness matrix vectors and a visual representation. The contact area of the magnetic fluid with rough surfaces was determined by mathematical modeling. The experimental studies were performed on a test bench. Wear sleeves and poles made of various steels with different roughness parameters were used. Models of MFS clearances formed by surfaces with different roughness have been obtained. The contact areas of the magnetic fluid with the surfaces of MFS at different roughness values have been determined. Nonlinear dependences and variation limits of the friction torque and MFS temperature on the surface roughness of the poles and sleeves, rotation frequencies of the electric motor, and the external temperature have been obtained. Clearance models allow determining the roughness of MFS surfaces. The developed experimental unit allows carrying out studies on the effect of changes of design parameters and operating conditions on the performance indicators of MFS. At a 5,21 time higher rotation frequency (from 556 to 2897 rpm), the MFS temperature can increase by up to 2 times, the friction torque – by up to 2,2 times. If the temperature rises by 50 оC, the friction torque can drop by up to 3 times. With an increase in the surface roughness from 0,357 to 7,21 μm, the temperature of the MFS can rise by 20 %, and the friction torque by 55 %.

scholarly journals Research on friction torque analysis of planetary roller screw mechanism considering load distribution

2018 ◽  
Author(s):  
Fajin Gan ◽  
Pengcheng Mao ◽  
Shicheng Zheng ◽  
Guangliang Li ◽  
Shupeng Xin
Keyword(s):  
Load Distribution ◽  
Friction Torque ◽  
Roller Screw ◽  
Torque Analysis ◽  
Screw Mechanism

scholarly journals Transient thermal analysis of standard planetary roller screw mechanism based on finite element method

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881230 ◽  
Author(s):  
Chuanming Du ◽  
Geng Liu ◽  
Guan Qiao ◽  
Shangjun Ma ◽  
Wei Cai
Keyword(s):  
Finite Element Method ◽  
Thermal Analysis ◽  
Finite Element ◽  
Friction Torque ◽  
Transient Thermal Analysis ◽  
Contact Points ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Transient Thermal ◽  
Element Method

The thermal behavior of the standard planetary roller screw mechanism needs to be investigated since the large amount of heat generated by the friction torque on multiple contact points during the transmission process. In this article, a simplified transmission system model of standard planetary roller screw mechanism is first established for the finite element analysis. Second, the friction torque of standard planetary roller screw mechanism is calculated and the boundary conditions of thermal analysis are deduced. Then, the transient thermal analysis of the standard planetary roller screw mechanism based on finite element method is conducted by considering the moving heat source and thus temperature field distribution at any time and the temperature rise curve at different positions of the standard planetary roller screw mechanism can be obtained. Finally, the correlation between the experimental data and the calculated values confirms the validity of the proposed thermal model for the transient thermal analysis.

Optimization Design of Rectangular Cross-Sectional Wire Race Ball Bearing

2014 ◽  
Vol 541-542 ◽  
pp. 553-558
Author(s):  
Yi Zhao ◽  
Jin Yao ◽  
Chun Tong
Keyword(s):  
Optimization Design ◽  
Ball Bearing ◽  
Design Method ◽  
Optical Design ◽  
Maximum Load ◽  
Friction Torque ◽  
Design Parameters ◽  
Original Sample ◽  
Cross Sectional ◽  
Design Specifications

Wire race ball bearing with large radial size and small axial size, saves space extremely, and is widely used in rotary devices of large machineries. This paper establishes a mathematical model of optimization design of rectangular cross-sectional wire race ball bearing,and considers minimum friction torque as objective function, and analyses constraints of contact intensity and design specifications of wire race ball bearing, and forges an optical design method that determines the number of balls, the diameter of ball, the contact angle and the diameter of ball center circle as optimal design parameters, to attain the purpose of extending bearings life. Comparing results of Optimization with original sample, the friction torque of ball that bears maximum load reduces by 10.20%. This method provides a reference for conducting further scientific researches on wear of wire race ball bearing.

An improved thermal estimation model of the inverted planetary roller screw mechanism

2018 ◽  
Vol 232 (23) ◽  
pp. 4430-4446 ◽  
Author(s):  
Guan Qiao ◽  
Geng Liu ◽  
Shangjun Ma ◽  
Zhenghong Shi ◽  
Yawen Wang ◽  
...  
Keyword(s):  
Heat Generation ◽  
Mechanical Response ◽  
High Load ◽  
Operating Conditions ◽  
Electrical Machine ◽  
Conductive Heat ◽  
Actuation System ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Mechanical Actuation

The inverted planetary roller screw mechanism has recently become competitive in the electro-mechanical actuation system due to its high load-carrying capacity and small assembly size. However, a significant amount of heat at the frictional contact interfaces and power loss inside the electrical machine can be naturally generated in a compact and high-load inverted planetary roller screw mechanism system. The conductive heat leads to the temperature rise of inverted planetary roller screw mechanism components that subsequently results in thermal drift and error as well as the actuation accuracy degradation. An analytical approach is applied to calculate the friction torque of the contact pairs and support bearings in the inverted planetary roller screw mechanism system. As the thermal load, heat generation is derived from the friction in nut-roller-screw section and bearings. Then, the heat generation and convection boundary conditions are formulated to facilitate thermal behavior analysis. Finally, using the finite element method, steady-state and transient thermal-mechanical coupling analyses are performed to estimate the temperature distribution and thermal expansion of the inverted planetary roller screw mechanism components. Computational results reveal that operating conditions of rotation speed and external load have significant influence on the thermal characteristics of the inverted planetary roller screw mechanism. This study can serve as a foundation for modeling temperature field and analyzing coupled thermal-mechanical response of inverted planetary roller screw mechanism in electro-mechanical actuation system, which can be useful in determining thermal error compensation.

Kinematics and Efficiency Analysis of the Planetary Roller Screw Mechanism

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Steven A. Velinsky ◽  
Baeksuk Chu ◽  
Ty A. Lasky
Keyword(s):  
Elastic Deformation ◽  
Carrying Capacity ◽  
Kinematic Analysis ◽  
Efficiency Analysis ◽  
Ball Screw ◽  
Load Carrying Capacity ◽  
Equilibrium Conditions ◽  
Load Carrying ◽  
Roller Screw ◽  
Screw Mechanism

This paper analyzes the kinematics and the efficiency of the planetary roller screw mechanism (RSM) to provide a fundamental basis to support its various applications. The mechanical structure and practical advantages are presented in comparison with the conventional ball screw mechanism (BSM). Kinematic analysis involves derivation of the angular and axial motions, as well as the development of the slip pattern between the contacting components. Results show that for any motion of the RSM slip always occurs. Kinematic analysis including elastic deformation is also presented. The load carrying capacity and efficiency of the RSM are derived based on geometric and equilibrium conditions, and the results are compared with the BSM.

Optimizing a Helical Groove Seal With Grooves on Both the Rotor and Stator Surfaces

2017 ◽  
Author(s):  
Cori Watson ◽  
Houston G. Wood
Keyword(s):  
Axial Flow ◽  
Helix Angle ◽  
Operating Conditions ◽  
Design Parameters ◽  
Screw Pump ◽  
Performance Function ◽  
Seal Design ◽  
Interaction Terms ◽  
Helical Groove ◽  
Groove Seal

Helical groove seals are non-contacting annular seals commonly used in pumps within the impeller stages to sustain a pressure differential for a given leakage. Helical groove seals have continuously cut grooves, like the threads of a screw, on the surface of the rotor, the surface of the stator, or both. The two main components of the flow within helical groove seals are axial flow and groove flow. The axial flow serves to reduce the leakage by dissipating kinetic energy as the fluid expands in the grooves and then is forced to contract within the jet stream region. The groove flow serves to reduce the leakage by acting as screw pump. The fluid within the grooves is displaced towards the high pressure region as it spins with the rotor. Previous work has shown that seals with grooves on both the surface of the rotor and the surface of the stator can sustain higher pressure differentials for a given leakage than seals with grooves on only one surface. The goal of this study is to optimize the leakage performance of a double surface helical groove seal for a given set of operating conditions. To accomplish this goal, simulations are run in ANSYS CFX. A sufficient mesh with appropriate boundary layers is determined from the mesh independence study. The turbulence model is k-ε turbulence for water at 25°C. This is the first paper to present numerical results for the performance of helical groove seals with grooves on both the rotor and the stator. The design parameters used in the optimization are inner (rotor) groove size, inner helix angle, outer (stator) groove size, and outer helix angle. A Kennard-Stone algorithm, which optimally spaces the simulations within the design space, is used to select the designs to be simulated. A multifactor quadratic regression is derived. Backward regression is used to reduce the performance function to only statistically significant terms. Finally, the optimal seal design is derived from the performance function and is simulated to demonstrate the predictive power of the performance function. Interaction terms for the rotor and stator design parameters will be used to explore the mechanism whereby helical groove seals with grooves on both the rotor and the stator surfaces are able to have lower leakage than helical groove seals with grooves on just one surface. The end result of this study is a seal design which minimizes leakage and therefore improve machine efficiency.

scholarly journals Load Sharing Multiobjective Optimization Design of a Split Torque Helicopter Transmission

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Chenxi Fu ◽  
Ning Zhao ◽  
Yongzhi Zhao
Keyword(s):  
Multiobjective Optimization ◽  
Optimization Design ◽  
Optimal Solution ◽  
Load Sharing ◽  
Operating Conditions ◽  
Design Parameters ◽  
Nonlinear Dynamic Model ◽  
Nsga Ii ◽  
Reference Design ◽  
Split Torque

Split torque designs can offer significant advantages over the traditional planetary designs for helicopter transmissions. However, it has two unique properties, gap and phase differences, which result in the risk of unequal load sharing. Various methods have been proposed to eliminate the effect of gap and promote load sharing to a certain extent. In this paper, system design parameters will be optimized to change the phase difference, thereby further improving load sharing. A nonlinear dynamic model is established to measure the load sharing with dynamic mesh forces quantitatively. Afterwards, a multiobjective optimization of a reference split torque design is conducted with the promoting of load sharing property, lightweight, and safety considered as the objectives. The load sharing property, which is measured by load sharing coefficient, is evaluated under multiple operating conditions with dynamic analysis method. To solve the multiobjective model with NSGA-II, an improvement is done to overcome the problem of time consuming. Finally, a satisfied optimal solution is picked up as the final design from the Pareto optimal front, which achieves improvements in all the three objectives compared with the reference design.

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