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.

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.

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.

A PLANETARY GEAR TRAIN WITH RING-INVOLUTE TOOTH

2008 ◽  
Vol 32 (2) ◽  
pp. 251-266
Author(s):  
Shyue-Cheng Yang ◽  
Tsang-Lang Liang
Keyword(s):  
Planetary Gear ◽  
Conjugate Problem ◽  
Gear Ratio ◽  
Gear Train ◽  
Tooth Surface ◽  
The Sun ◽  
Ring Gear ◽  
Planetary Gear Train ◽  
Envelope Method ◽  
Planet Gear

This paper proposes a planetary gear train with ring-involute tooth profile. Inherent in a planetary gear train is the conjugate problem among the sun, the planet gears and the ring gear. The sun gear and the planet gear can be obtained by applying the envelope method to a one-parameter family of a conical tooth surface. The conical tooth rack cutter was presented in a previous paper [5]. The obtained planet gear then becomes the generating surface. The double envelope method can be used to obtain the envelope to the family of generating surfaces. Subsequently the profile of a ring gear of the planetary gear trains can be easily obtained, and using the generated planet gear and applying the gear theory, the ring gear is generated. To illustrate, the planetary gear train with a gear ratio of 24:10:7 is presented. Using rapid prototyping and manufacturing technology, a sun gear, four planet gears, and a ring gear are designed. The RP primitives provide an actual full-size physical model that can be analyzed and used for further development. Results from these mathematical models are applicable to the design of a planetary gear train.

Evaluation of Ring Gear Tooth Stress

2002 ◽  
Author(s):  
Loc Duong ◽  
Michael McCune ◽  
Kazem Kazerounian
Keyword(s):  
Structural Integrity ◽  
Gear Tooth ◽  
Three Dimensional ◽  
Weight Ratio ◽  
Helix Angle ◽  
Gear Train ◽  
Ring Gear ◽  
Gear Mesh ◽  
Epicyclic Gear ◽  
Three Dimensional Finite Element

To optimize the operating speeds of the low spool of a gas turbine engine together with the overall transmitted horsepower to weight ratio, an epicyclic gear train is used to transmit power from the turbine section to the propeller shaft (as in PWC PT6 engine) or to the fan shaft (as in Honeywell TFE-731 engine). In order to achieve an optimum design in view of structural integrity, the stress characteristics of each component of the epicyclic gear train needs to be optimized. In general, the external gear mesh (as in the sun and planet mesh), needs a back up rim to tooth thickness ratio of not less than 1.2. However, this is not always the case for internal gear mesh such as the ring gear. The objective of this paper is to present analytical results on the stress behavior of the ring gear under different loading conditions. Three dimensional finite element method is employed to study the internal tooth fillet stress under the effects of fillet radius, gear rim thickness, pressure angle and helix angle. This study is the first part of a work aiming to determine the failure mode of the ring gear and leading to design optimization of epicyclic systems.

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.

The Research on Natural Characteristic and Eigensensitivity of Ravingneaux Compound Planetary Gear Sets

2013 ◽  
Vol 446-447 ◽  
pp. 590-596
Author(s):  
Bo Qian ◽  
Shi Jing Wu
Keyword(s):  
Natural Frequency ◽  
Planetary Gear ◽  
Torsional Stiffness ◽  
Ring Gear ◽  
Vibration Model ◽  
Planetary Gear Sets ◽  
Planet Gear ◽  
Natural Characteristic ◽  
Gear Ring ◽  
The Moment

The dynamic model of Ravingneaux compound planetary gear sets has been built. Then the Natural frequency and vibration model have been solved in the Ravingneaux compound planetary gear sets. The eigensensitivity to parameters have been researched based on the dynamical model. The varying trend of natural frequency according to the varying of parameters have been researched, which include gear mass (sun gear, ring gear , or planet gear), the moment of inertia of gears, the support stiffness , the torsional stiffness.

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.

scholarly journals Gear Tooth Stress Measurements of Two Helicopter Planetary Stages

1992 ◽  
Author(s):  
Timothy L. Krantz
Keyword(s):  
Load Distribution ◽  
Gear Tooth ◽  
Nasa Lewis Research ◽  
Ring Gear ◽  
Gear Teeth ◽  
Load Variation ◽  
Planet Gear ◽  
Helicopter Main Rotor ◽  
Stress Variations ◽  
Root Location

Abstract Two versions of the planetary reduction stages from U.S. Army OH-58 helicopter main rotor transmissions were tested at the NASA Lewis Research Center. One sequential and one nonsequential planetary were tested. Sun gear and ring gear teeth strains were measured, and stresses were calculated from the strains. The alternating stress at the fillet of both the loaded and unloaded sides of the teeth and at the root of the sun gear teeth are reported. Typical stress variations as the gear tooth moves through the mesh are illustrated. At the tooth root location of the thin-rimmed sun gear, a significant stress was produced by a phenomenon other than the passing of a planet gear. The load variation among the planets was studied. Each planet produced its own distinctive load distribution on the ring and sun gears. The load variation was less for a three-planet, nonsequential design as compared to that of a four-planet, sequential design. The results reported enhance the data base for gear stress levels and provide data for the validation of analytical methods.

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