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.

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.

scholarly journals Computer-Aided Sketching of Epicyclic-Type Automatic Transmission Gear Trains

1994 ◽  
Author(s):  
Goutam Chatterjee ◽  
Lung-Wen Tsai
Keyword(s):  
Automatic Transmission ◽  
Reverse Transformation ◽  
Epicyclic Gear ◽  
Computer Aided ◽  
Planet Gear ◽  
Gear Mechanism ◽  
Gear Trains ◽  
Transmission Gear

Abstract The enumeration of epicyclic gear mechanisms in the form of graphs gives rise to the need of a methodology for reverse transformation, that is, for constructing the mechanisms from graphs. This paper addresses the issue by discretizing an epicyclic gear mechanism into Fundamental Geared Entities. Further, these geared entities are shown to be a conglomeration of four primitives; namely, the carrier, sun, ring, and the planet gear. An algorithm is formulated to create the entities from a graph by using these primitives. The entities are then connected together to form a mechanism.

Geometric Construction of Piecewise Line-Symmetric Spherical Motions Using Quaternion Biarcs

2006 ◽  
Author(s):  
Carlos A. Trujillo ◽  
Q. J. Ge
Keyword(s):  
Gear Train ◽  
Robot Path Planning ◽  
B Spline ◽  
Cam Mechanism ◽  
Epicyclic Gear ◽  
Cad Cam ◽  
Planet Gear ◽  
Velocity Constraints ◽  
C1 Continuity ◽  
Robot Path

This paper employs quaternion biarcs to interpolate a set of orientations with angular velocity constraints. The resulting quaternion curve represents a piecewise spherical line-symmetric rational motion with C1 continuity. Since a quaternion arc corresponds to the motion of the planet gear in a special spherical epicyclic gear train, each segment of the quaternion biarcs can be realized with such an epicyclic gear train. Quaternion biarcs may be used to approximate B-spline quaternion curves that represent rational spherical motions that have applications in robot path planning, CAD/CAM, mechanism design, and computer graphics.

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.

scholarly journals Computer-Aided Sketching of Epicyclic-Type Automatic Transmission Gear Trains

1996 ◽  
Vol 118 (3) ◽  
pp. 405-411 ◽  
Author(s):  
G. Chatterjee ◽  
Lung-Wen Tsai
Keyword(s):  
Automatic Transmission ◽  
Reverse Transformation ◽  
Epicyclic Gear ◽  
Computer Aided ◽  
Planet Gear ◽  
Gear Mechanism ◽  
Gear Trains ◽  
Transmission Gear

The enumeration of epicyclic gear mechanisms in the form of graphs gives rise to the need of a methodology for reverse transformation, that is, for constructing the mechanisms from graphs. This paper addresses the issue by discretizing an epicyclic gear mechanism into Fundamental Geared Entities. Further, these geared entities are shown to be a conglomeration of four primitives; namely, the carrier, sun, ring, and the planet gear. An algorithm is formulated to create the entities from a graph by using these primitives. The entities are then connected together to form a mechanism.

scholarly journals Method and Device for Speed Change by the Epicyclic Gear Train with Stepped-Planet Gear Set

2016 ◽  
Vol 38 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Volodymyr Malashchenko ◽  
Oleh Strilets ◽  
Volodymyr Strilets
Keyword(s):  
Change Management ◽  
Gear Train ◽  
Closed Circuit ◽  
Theoretical Research ◽  
Control Element ◽  
Ring Gear ◽  
Variable Speed ◽  
Epicyclic Gear ◽  
Planet Gear ◽  
Speed Change

Abstract The article describes new method and device for continuously variable speed change management via compound epicyclic gearing with composite planet gears and closed circuit hydrosystem, when the speed control element is either outer ring gear (annulus) or the carrier or sun gear. In each case, the control element connected to closed circuit hydrosystem and can be in motion or immovable depending on the bandwidth of hydrosystem’s regulating throttle. We had held theoretical research and received graphic dependences between velocities of driving, control and driven elements by means of computer programing.

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.

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