Cycloid Drives With Machining Tolerances: Part I — Kinematic Analysis

1987 ◽  
Author(s):  
J. G. Blanche ◽  
D. C. H. Yang
Keyword(s):  
High Efficiency ◽  
Dynamic Instability ◽  
Torque Ripple ◽  
Gear Train ◽  
Space Applications ◽  
Design Synthesis ◽  
Input Shaft ◽  
Epicyclic Gear ◽  
Speed Reducer ◽  
Gear Mechanism

Abstract The cycloidal speed reducer, or cycloid drive, is an epicyclic gear train in which the profile of the planet gear is an epitrochoid and the annular sun gear has rollers as its teeth. The cycloid drive has very high efficiency and small size, in comparison with a conventional gear mechanism, making it an attractive candidate for limited space applications. On the other hand, in this type of transmissions there exist two major drawbacks, namely, backlash and torque ripple Backlash, the angle through which the output shaft can rotate when the input shaft is held fixed, has a degrading effect on the output accuracy. Torque ripple, the variation in mechanical advantage as the input shaft rotates, causes vibrations and could lead to dynamic instability of the machinery. If the cycloid drive were manufactured to the ideal dimensions, there would be no backlash nor torque ripple. However, in reality, there will always be some machining tolerances. In this paper an analytical model is developed which models the cycloid drive with machining tolerances. This model is used in Part II of this investigation to determine the effect of machining tolerances on backlash and torque ripple. As a result, simple and practical equations for design synthesis of this type of drives are formulated.

Cycloid Drives With Machining Tolerances

1989 ◽  
Vol 111 (3) ◽  
pp. 337-344 ◽  
Author(s):  
J. G. Blanche ◽  
D. C. H. Yang
Keyword(s):  
High Efficiency ◽  
Dynamic Instability ◽  
Torque Ripple ◽  
Gear Train ◽  
Space Applications ◽  
Input Shaft ◽  
Epicyclic Gear ◽  
Speed Reducer ◽  
Planet Gear ◽  
Gear Mechanism

The cycloidal speed reducer, or cycloid drive, is an epicyclic gear train in which the profile of the planet gear is an epitrochoid and the annular sun gear has rollers as its teeth. The cycloid drive has very high efficiency and small size, in comparison with a conventional gear mechanism, making it an attractive candidate for limited space applications. On the other hand, in this type of transmissions there exist two major drawbacks, namely, backlash and torque ripple. Backlash, the angle through which the output shaft can rotate when the input shaft is held fixed, has a degrading effect on the output accuracy. Torque ripple, the variation in mechanical advantage as the input shaft rotates, causes vibrations and could lead to dynamic instability of the machinery. If the cycloid drive were manufactured to the ideal dimensions, there would be no backlash nor torque ripple. However, in reality, there will always be some machining tolerances. In this paper an analytical model is developed which models the cycloid drive with machining tolerances. Consequently, the effect of machining tolerances on backlash and torque ripple are investigated. It is found that both the backlash and the torque ripple are inherent periodic functions of the input crank angle.

The Synthesis of a Transmission With Intersecting Axes for Rectifying and Reducing a Periodic Speed: A Preliminary Study

1996 ◽  
Author(s):  
ChinPun Teng ◽  
Jorge Angeles ◽  
Khaled Khader
Keyword(s):  
Power Transmission ◽  
Spur Gear ◽  
Transmission Mechanism ◽  
Gear Train ◽  
Motor Speed ◽  
Input Shaft ◽  
Speed Reducer ◽  
Chain Transmission ◽  
Preliminary Study ◽  
Bevel Gear Train

Abstract In power-transmission tasks, the mechanical designer faces sometimes the problem of transmitting a constant angular velocity from a shaft at the output of a motor to another shaft connected to the load. When the first shaft is connected to the rotor of the motor via a gear box directly, and the motor is supplied with an effective speed control system, then the problem of power transmission can be readily solved using a spur-gear train if the shafts are parallel; a bevel-gear train if the two shafts intersect; and a gear train with skew axes if the shafts are neither parallel nor intersecting. However, instances occur in practice whereby the rotor of the motor is connected to a speed reducer that does not preserve the constancy of the motor speed, e.g., when a sprocket-chain transmission is used. In these cases, the input speed is not constant, but periodic. This paper focuses on the design of a transmission mechanism that serves to rectify the periodic speed of an input shaft to deliver a constant speed to the load. Moreover, in doing this, we show that it is possible to reduce the speed delivered by the motor as well. The problem of power transmission between parallel axes was reported in an earlier paper. Here, we report work on the corresponding problem when the shafts intersect. In the two cases, a transmission based on cams is synthesised, this paper reporting on a design based on spherical cams.

Cycloid Drives With Machining Tolerances: Part II — Computer-Aided Design

1987 ◽  
Author(s):  
D. C. H. Yang ◽  
J. G. Blanche
Keyword(s):  
Computer Aided Design ◽  
Torque Ripple ◽  
Gear Ratio ◽  
Performance Indices ◽  
Design Synthesis ◽  
Input Shaft ◽  
Crank Angle ◽  
Computer Aided ◽  
And Performance ◽  
Aided Design

Abstract In this paper a computer-aided design package is developed for analyzing cycloid drives with machining tolerance. It is found that both the backlash and the torque ripple are periodic functions of the input crank angle. The frequency is equal to the number of teeth on the ring gear times the input shaft frequency. Also, simple and practical formulas for design synthesis of these types of transmissions are developed with the consideration of tolerance, drive parameters (gear ratio, normalized tooth height and pitch diameter) and performance indices (backlash and torque ripple).

The Mechanical Efficiency of Harmonic Drives: A Simplified Model

2020 ◽  
pp. 1-17
Author(s):  
Federico Gravagno ◽  
Victor Mucino ◽  
Ettore Pennestri
Keyword(s):  
Mechanical Efficiency ◽  
Angular Speed ◽  
Gear Train ◽  
Simplified Model ◽  
Significant Feature ◽  
Main Concern ◽  
Harmonic Drive ◽  
Space Applications ◽  
New Model ◽  
Epicyclic Gear

Abstract Harmonic drives are widely used devices in robotic and space applications. As for any device transmitting motion, its mechanical efficiency is one of the main concern for the designer. In this paper it is proposed a new model to estimate this significant feature. The proposed approach makes use of the kinematic correspondence between the harmonic drive and an epicyclic gear train. Although the authors introduced crude approximations to describe the complex tribological phenomena during harmonic drive teeth meshing, the numerical results match the trend of experimental. In particular, assuming the harmonic drive working at the rated torque, the plots of the mechanical efficiency versus different parameters such as temperature and angular speed have been reported.

Enumeration of Feasible Clutching Sequences of Epicyclic Gear Mechanisms

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Shaker S. Hassan
Keyword(s):  
Artificial Intelligence ◽  
Velocity Ratio ◽  
Automatic Transmission ◽  
Gear Train ◽  
Artificial Intelligence Technique ◽  
Transmission Mechanisms ◽  
Epicyclic Gear ◽  
Gear Mechanism ◽  
Algorithmic Technique ◽  
Intelligence Technique

A new methodology for enumeration of feasible clutching sequences of epicyclic gear mechanism (EGM) composed of two or more fundamental gear entities is presented. The method relies on previous work on algorithmic technique. It improves on existing techniques used for automatic transmission mechanisms in its ability to accurately solve the kinematics of geared mechanisms and estimating their velocity ratios and arranging them in a descending order in a simpler manner without depending on certain gear sizes. Twelve velocity-ratio-relations are derived for any four coaxial links of an epicyclic gear train. These velocity-ratio-relations are three more than the nine relations given in literature. In addition, the velocity ratios can be arranged in a descending sequence without using complicated artificial intelligence technique or complicated computer algorithm. The present methodology is judged to be more efficient for enumeration of all feasible clutching sequences of an EGM.

Reliability Analysis and Design of Epicyclic Gear Trains

1979 ◽  
Vol 101 (4) ◽  
pp. 625-632 ◽  
Author(s):  
S. S. Rao
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Design Criterion ◽  
Gear Train ◽  
Design Parameters ◽  
Analysis And Design ◽  
Input Shaft ◽  
Reliability Based Design ◽  
Epicyclic Gear ◽  
Gear Trains

The concepts of system reliability are applied for the structural reliability analysis and design of epicyclic gear trains. The reliability analysis is based on the representation of an epicyclic gear train as a series-parallel network. The power transmitted, the speed of the input shaft, the center distance between the gear pairs and the permissible stresses are assumed to be random variables following normal distribution. The layout of the gears and the speed ratios are assumed to be known. The face widths of the gears are taken as random design parameters. The design criterion is that the reliability of the gear train either in bending or surface wear failure mode at any of the output speeds must be equal to a specified value. The design of an epicyclic transmission system which gives four forward speeds and one reverse speed is considered for illustration. The results of the reliability-based design of the gear train are compared with those of the conventional deterministic design.

Topological Synthesis of Epicyclic Gear Trains Using Vertex Incidence Polynomial

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Vinjamuri Venkata Kamesh ◽  
Kuchibhotla Mallikarjuna Rao ◽  
Annambhotla Balaji Srinivasa Rao
Keyword(s):  
High Velocity ◽  
Mechanical Energy ◽  
Gear Train ◽  
Recursive Method ◽  
Gear Pair ◽  
Simple Method ◽  
Epicyclic Gear ◽  
Thick Line ◽  
Gear Trains ◽  
Isomorphic Graphs

Epicyclic gear trains (EGTs) are used in the mechanical energy transmission systems where high velocity ratios are needed in a compact space. It is necessary to eliminate duplicate structures in the initial stages of enumeration. In this paper, a novel and simple method is proposed using a parameter, Vertex Incidence Polynomial (VIP), to synthesize epicyclic gear trains up to six links eliminating all isomorphic gear trains. Each epicyclic gear train is represented as a graph by denoting gear pair with thick line and transfer pair with thin line. All the permissible graphs of epicyclic gear trains from the fundamental principles are generated by the recursive method. Isomorphic graphs are identified by calculating VIP. Another parameter “Rotation Index” (RI) is proposed to detect rotational isomorphism. It is found that there are six nonisomorphic rotation graphs for five-link one degree-of-freedom (1-DOF) and 26 graphs for six-link 1-DOF EGTs from which all the nonisomorphic displacement graphs can be derived by adding the transfer vertices for each combination. The proposed method proved to be successful in clustering all the isomorphic structures into a group, which in turn checked for rotational isomorphism. This method is very easy to understand and allows performing isomorphism test in epicyclic gear trains.

Design of an Epicyclic Transmission for Speed Control of a Turbine-Generator System

1992 ◽  
Author(s):  
Indranil Barman ◽  
Donald R. Flugrad
Keyword(s):  
Control Method ◽  
Equations Of Motion ◽  
Speed Control ◽  
Gear Train ◽  
Turbine Generator ◽  
Generator System ◽  
Epicyclic Gear ◽  
The Face ◽  
Fine Control ◽  
Parameter Values

Abstract An improved speed control method is proposed for a turbine-generator system. Whereas the present method employs a steam valve to control the flow of steam according to the desired output, the proposed system uses an epicyclic gear train to provide fine control of the speed, while coarse control is still maintained through the steam valve. The systematic design of such a gear train is the objective of this project. Two configurations are considered as suitable candidates. After the transmissions are analyzed to obtain the speed and torque relations, the dynamic equations of motion and control equations for the systems are derived for simulation purposes. The simulations are then conducted for various load cases and parameter values to determine a suitable design for application in the power industry. The final configuration allows constant generator output speeds to be reliably maintained in the face of significant load disturbances.

Meshing Efficiency Analysis of Two Degree-of-Freedom Epicyclic Gear Trains

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Essam Lauibi Esmail
Keyword(s):  
Reference Frame ◽  
Power Efficiency ◽  
Power Flow ◽  
Flow Direction ◽  
Efficiency Analysis ◽  
Degree Of Freedom ◽  
Gear Train ◽  
Epicyclic Gear ◽  
Gear Trains ◽  
Two Degree Of Freedom

The concept of potential power efficiency is introduced as the efficiency of an epicyclic gear train (EGT) measured in any moving reference frame. The conventional efficiency can be computed in a carrier-moving reference frame in which the gear carrier appears relatively fixed. In principle, by attaching the reference frame to an appropriate link, torques can be calculated with respect to each input, output, or (relatively) fixed link in the EGT. Once the power flow direction is obtained from the potential power ratio, the torque ratios are obtained from the potential power efficiencies, the particular expression of the efficiency of the EGT is found in a simple manner. A systematic methodology for the efficiency analysis of one and two degree-of-freedom (DOF) EGTs is described, and 14 ready-to-use efficiency formulas are derived for 2DOF gear pair entities (GPEs). This paper includes also a discussion on the redundancy of the efficiency formulas used for 1DOF GPEs. An incomplete in the efficiency formulas in previous literature, which make them susceptible to wrong application, is brought to light.

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