Efficiency of the High Contact Ratio Involute Spur Gears With Asymmetric Teeth

2010 ◽  
Author(s):  
F. Karpat ◽  
S. Ekwaro-Osire
Keyword(s):  
High Performance ◽  
Load Capacity ◽  
Design Parameters ◽  
Spur Gears ◽  
Contact Ratio ◽  
Pressure Angle ◽  
Low Weight ◽  
Standard Design ◽  
Load Carrying ◽  
The Impact

Gears with asymmetric teeth have unique potential for application in gearboxes, particularly when uni-directional loading is applied. Most recently, gears with asymmetric teeth have received much attention for use in applications that require high performance due to increased load capacity. Such applications include aircraft and wind turbine. These gears offer flexibility to designers due to their non-standard design. In asymmetric teeth, the geometry of the drive side is not to be symmetric to the coast side. In other words, the pressure angle on the drive side is greater or smaller than that on the coast side. Asymmetry between tooth sides provide vital in obtaining key properties, such as high load carrying capacity, low weight, low wear or low vibration. In order to effectively design asymmetric teeth, it is necessary to perform analyses on the efficiency of these gears under various loading. In this study, the results obtained on high contact ratio involute spur gears with asymmetric teeth are presented and discussed. The impact of a few design parameters, such as pressure angle or tooth height, on sliding velocities and friction is investigated and illustrated with numerical examples.

Modeling and Analysis of the Meshing Losses of Involute Spur Gears in High-Speed and High-Load Conditions

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
L. Chang ◽  
Yeau-Ren Jeng ◽  
Pay-Yau Huang
Keyword(s):  
High Speed ◽  
High Performance ◽  
High Load ◽  
Design Parameters ◽  
Physical Parameters ◽  
Spur Gears ◽  
Modeling And Analysis ◽  
Helical Gears ◽  
Viscosity Coefficients ◽  
Pressure Angle

A first-principle based mathematical model is developed in this paper to analyze the meshing losses in involute spur gears operating in high-load and high-speed conditions. The model is fundamentally simple with a few clearly defined physical parameters. It is computationally robust and produces meaningful trends and relative magnitudes of the meshing losses with respect to the variations of key gear and lubricant parameters. The model is evaluated with precision experimental data. It is then used to study the effects of various gear and lubricant parameters on the meshing losses including gear module, pressure angle, tooth addendum height, thermal conductivity, and lubricant pressure-viscosity and temperature-viscosity coefficients. The results and analysis suggest that gear module, pressure angle, and lubricant pressure-viscosity and temperature-viscosity coefficients can significantly affect the meshing losses. They should be the design parameters of interest to further improve the energy efficiency in high-performance, multistage transmission systems. Although the model is developed and results obtained for spur gears, the authors believe that the trends and relative magnitudes of the meshing losses with respect to the variations of the gear and lubricant parameters are still meaningful for helical gears.

Analytical Model of the Efficiency of Spur Gears: Study of the Influence of the Design Parameters

2011 ◽  
Author(s):  
Miguel Pleguezuelos ◽  
Jose´ I. Pedrero ◽  
Miryam B. Sa´nchez
Keyword(s):  
Load Distribution ◽  
Gear Ratio ◽  
Design Parameters ◽  
Spur Gears ◽  
Transmitted Power ◽  
Power Losses ◽  
Contact Ratio ◽  
Complete Study ◽  
Uniform Model ◽  
Analytical Expressions

An analytic model to compute the efficiency of spur gears has been developed. It is based on the application of a non-uniform model of load distribution obtained from the minimum elastic potential criterion and a simplified non-uniform model of the friction coefficient along the path of contact. Both conventional and high transverse contact ratio spur gears have been considered. Analytical expressions for the power losses due to friction, for the transmitted power and for the efficiency are presented. From this model, a complete study of the influence of some design parameters (as the number of teeth, the gear ratio, the pressure angle, the addendum modification coefficient, etc.) on the efficiency is presented.

Influence of Undercut on the Load Capacity for Involute Teeth With Small Pressure Angle

2003 ◽  
Author(s):  
Jose´ I. Pedrero ◽  
Mariano Arte´s ◽  
Carlos Garci´a-Masia´
Keyword(s):  
Load Capacity ◽  
Geometrical Parameters ◽  
Contact Ratio ◽  
Helical Gears ◽  
Small Pressure ◽  
Pressure Angle ◽  
Number Of Teeth ◽  
Minimum Number

The minimum number of teeth to avoid undercut on involute spur and helical gears depends on the pressure angle, among some other geometrical parameters. Higher number of teeth is required if the pressure angle becomes smaller. However, the contact ratio may be increased by reducing the pressure angle, which means the load is distributed along a longer line of contact. In many cases, even if undercut arises and teeth are weakened, both effects may result in higher load capacity for the gears. This paper presents a study on the influence of the pressure angle on the contact ratio, and through it on the length of contact and the load capacity, including a discussion on the condition to improve the load capacity by reducing the pressure angle beyond the undercut limit.

Further Evaluation of Spur Gear Tooth Profile Designs Used in Heavily Loaded Transmissions

2011 ◽  
Author(s):  
Nihat Yıldırım ◽  
Hakan I˙s¸c¸i ◽  
Abdullah Akpolat
Keyword(s):  
Gear Tooth ◽  
Transmission Error ◽  
Spur Gear ◽  
Tooth Profile ◽  
Design Parameters ◽  
Preference Order ◽  
Spur Gears ◽  
Tooth Root ◽  
Contact Ratio ◽  
Practical Applications

Aerospace applications require special procedures for component design and manufacturing. Spur gears of different designs, because of their simpler geometries, are used in vital units-transmissions of helicopters and alike aerospace vehicles. In this study, performances of various profile designs of previously researched low and high contact ratio spur gears with some realistic design parameters are studied. Effects of the realistic parameters of variable tooth pair stiffness, relief shape, and adjacent pitch error on Transmission Error (TE), tooth loads and root stresses are presented; composition of these parameters determines the efficiency of the gearbox assembly. Detail of minimization of tooth root stress through optimized/proper design of relief is described. More comprehensive comparison of the gear tooth profile design cases is done to be able to guide aerospace transmission designers for practical applications with realistic parameters for each of the design cases. A preference order is done among the design cases, depending on effect of some design parameters on the results such as tooth loads, tooth root stresses, TE curves and peak-to-peak TE values.

FRICTIONAL PROBLEMS IN CONTINUOUSLY VARIABLE TRANSMISSION BELT DRIVES

Tribologia ◽  
2017 ◽  
pp. 93-100 ◽  
Author(s):  
Wojciech SZCZYPIŃSKI-SALA ◽  
Krzysztof DOBAJ ◽  
Adam KOT
Keyword(s):  
High Performance ◽  
Angular Speed ◽  
Continuously Variable Transmission ◽  
Design Parameters ◽  
Belt Drive ◽  
Power Losses ◽  
Belt Drives ◽  
Variable Transmission ◽  
Drive Systems ◽  
The Impact

The article describes the results of the research carried out on the evaluation of the influence of friction pairs (rubber belt – belt pulley in belt drive) on the ability to transmit power. In order to determine the characteristics of the belt drive operation, measurements were made on a real belt drive from the drive train of a light two-wheeled vehicle. The measurement was carried out in conditions of changes in the dynamic load. The measurements of the belt slip on the belt pulley within the whole range of the changes of gear ratios and angular speed of the engine were made. During the tests, belts made from various rubber mixtures were compared. The values of the friction coefficients between the surface of belts and the belt pulley were measured. Model analyses of the impact of belt slip on the wheel related to the temperature of Belt drive elements were also made. Generally, one can ascertain that, in belt drive systems, power losses are a combination of speed losses and torque losses. The increase in the efficiency of belt drives is possible by decreasing power losses. It is possible to obtain the high performance of continuously variable transmission belt drives with a V- belt solely with the proper choice of the design parameters, which is possible only after the exact recognition of the operational characteristics unique to this class of belt drive systems.

scholarly journals Mathematical model of energy efficiency in internal spur gears

2019 ◽  
Vol 23 (Suppl. 5) ◽  
pp. 1801-1813
Author(s):  
Predrag Dobratic ◽  
Mileta Ristivojevic ◽  
Bozidar Rosic ◽  
Radivoje Mitrovic ◽  
Dragan Trifkovic
Keyword(s):  
Mathematical Model ◽  
Load Distribution ◽  
Energy Losses ◽  
Spur Gears ◽  
Contact Ratio ◽  
Cylindrical Gear ◽  
Heating Effects ◽  
Effective Efficiency ◽  
The Impact ◽  
The Mathematical Model

The impact of geometric parameters of teeth and lubricating oils to the efficiency of involute internal spur gears, when the transverse contact ratio is 2 < ?? ?3, has been analyzed in this paper. The mathematical model and computer program for determining the current and the effective value of the efficiency have been developed. The influence of the character of load distribution and energy losses due to heating effects during the meshing period is included in the factor of load distribution. The results of computer simulation are given in the form of a diagram of the current values of the efficiency during the meshing period. Also, the values of effective efficiency for the considered cylindrical gear pairs have been calculated.

A Virtual Tool for Wear Simulation of Standard and Non-Standard Spur Gears

2012 ◽  
Author(s):  
F. Karpat ◽  
S. Ekwaro-Osire ◽  
E. Karpat
Keyword(s):  
High Speed ◽  
High Performance ◽  
Failure Modes ◽  
Power Transmission ◽  
Wear Behavior ◽  
Gear Tooth ◽  
Load Capacity ◽  
High Load ◽  
Wear Depth ◽  
Spur Gears

There is an industrial demand for the increased performance of mechanical power transmission devices. This need in high performance is driven by high load capacity, high endurance, low cost, long life, and high speed. New designs and modifications in gears have been investigated to obtain high load carrying capacity and increased life with less volume and weight. Tooth wear is one of the major failure modes in gears. Although there are different classifications of wear mechanisms, wear on gears can be simply classified as mild wear, pitting, and severe wear, depending on the wear rate. These types of wear may lead to power transmission losses, decreased efficiency, increased vibration and noise, and gear tooth failure. This paper deals with the simulation of wear for standard and non-standard gears using an analytical approach. A numerical model for wear prediction of gear pair is developed. A wear model based on Archard’s equation is employed to predict wear depth. A MATLAB-based virtual tool is developed to analyze wear behavior of standard and non-standard spur gears with various gear parameters. In this paper, this virtual tool is introduced by using many numerical examples.

Influence of Geometry and Deformation on the Performance of Profiled Hydrosatic Thrust Bearings

2003 ◽  
Author(s):  
Jianpeng Feng ◽  
Harish Cherukuri ◽  
Robert E. Johnson ◽  
Noah Manring
Keyword(s):  
Contact Area ◽  
Thrust Bearing ◽  
Load Carrying Capacity ◽  
Ball Joint ◽  
Thrust Bearings ◽  
Lubrication Film ◽  
Deforma Tion ◽  
Standard Design ◽  
Load Carrying ◽  
The Impact

In a previous study, the authors investigated the effect of various thrust bearing profiles on the bearing performance and concluded that bearing performance is significantly influenced by the deformations resulting from lubrication film pressure. In the present work, results from a recent study on the effect of the interaction between the ball-joint and bearing on bearing deforma tion and hence, on bearing performance are reported. The motivation behind the study is to investigate the impact of raising or lowering the contact area between the ball-joint and bearing surface on bearing performance as this has the effect of influenceing the bearing deformation. Several designs involving various geometries of the bearing that affect the contact area are considered. The coupled fluid-solids problem is solved by using an iterative technique where the fluid problem is solved using the lubrication theory and the bearing deformation is analyzed by using the commercial FEA software ABAQUS standard. Results from the numerical simulations are compared with experimental results for the standard design of the bearing. The effect of varying the pocket width on the load carrying capacity of the bearing is also investigated.

scholarly journals Selection of Pressure Angle based on Dynamic Effects in Asymmetric Spur Gear with Fixed Normal Contact Ratio

2019 ◽  
Vol 69 (3) ◽  
pp. 303-310
Author(s):  
Benny Thomas ◽  
K. Sankaranarayansamy ◽  
S. Ramachandra ◽  
Suresh Kumar S.P.
Keyword(s):  
Gear Tooth ◽  
Transmission Error ◽  
Spur Gear ◽  
Dynamic Factor ◽  
Spur Gears ◽  
Contact Ratio ◽  
Normal Contact ◽  
Pressure Angle ◽  
Side Pressure ◽  
Static Transmission Error

Asymmetric spur gears are finding application in many fields including aerospace propulsion and automobile which demand unidirectional or relatively higher load on one side of the gear flank. Design intend to maximise the load carrying capacity of the drive side of asymmetric gear by increasing the pressure angle is achieved at the expense of coast side capacity. Multiple solution for coast to drive side pressure angle exist for a given contact ratio and each of these have relative merits and demerits. In the present work asymmetric spur gears of theoretically equal contact ratio as that of corresponding symmetric gears are selected to investigate the change in gear tooth static transmission error and dynamic behaviour with coast and drive side pressure angle. Study shows that dynamic factor of normal contact ratio asymmetric spur gears below resonance speed are relatively lower than corresponding symmetric gears of same module, contact ratio, number of teeth, coast side pressure angle and fillet radii. Results also show that, coast and drive side pressure angle can be suitably selected for a given contact ratio to reduce the single tooth and double tooth contact static transmission error and dynamic factor of asymmetric spur gears.

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