An Expression Method of Kinematic and Structure Diagrams for Planetary Gear Systems

2021 ◽  
pp. 145-156
Author(s):  
Vu Le Huy ◽  
Do Duc Nam
Keyword(s):  
Planetary Gear ◽  
Gear Systems

scholarly journals Reliability and Random Lifetime Models of Planetary Gear Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Peng Gao ◽  
Liyang Xie ◽  
Wei Hu
Keyword(s):  
Load Distribution ◽  
Planetary Gear ◽  
Working Process ◽  
Random Load ◽  
Working Mechanism ◽  
Dynamic Reliability ◽  
Reliability Models ◽  
Process Failure ◽  
Failure Dependence ◽  
Gear Systems

Conventional reliability models of planetary gear systems are mainly static. In this paper, dynamic reliability models and random lifetime models of planetary gear systems are developed with dynamic working mechanism considered. The load parameters, the geometric parameters, and the material parameters are taken as the inputs of the reliability models and the random lifetime models. Moreover, failure dependence and dynamic random load redistributions are taken into account in the models. Monte Carlo simulations are carried out to validate the proposed models. The results show that the randomness of the load distribution is obvious in the system working process. Failure dependence has significant influences on system reliability. Moreover, the dispersion of external load has great impacts on the reliability, lifetime distribution, and redundancy of planetary gear systems.

Effect of the bearing clearance on vibrations of a double-row planetary gear system

2019 ◽  
Vol 234 (2) ◽  
pp. 347-357
Author(s):  
Jing Liu ◽  
Shizhao Ding ◽  
Linfeng Wang ◽  
Hongwu Li ◽  
Jin Xu
Keyword(s):  
Contact Stiffness ◽  
Planetary Gear ◽  
Gear Ratio ◽  
Gear System ◽  
Double Row ◽  
External Torque ◽  
Bearing Clearance ◽  
Gear Systems ◽  
Planetary Gear System ◽  
Stiffness And Damping

The bearing clearance, external torque, and input speed can greatly affect vibrations of the planetary gear system. The double-row planetary gear systems are commonly used in the gearbox of special vehicles, which are the key parts to obtain a larger gear ratio. Although many works have been presented to study those factors on vibrations of the single-row planetary gear system, a few works were focused on vibrations of the double-row planetary gear system with the bearing clearance. To overcome this problem, a multi-body dynamic model of a double-row planetary gear system with six planet bearings and one supported bearing of the sun gear is presented. This model is the main part of a gear box transmission system. The new model is developed for studying the effect of the bearing clearance on the planetary system. The meshing stiffness and damping between the gears are obtained by current methods in the listed references, as well as the contact stiffness and damping in bearings. The liner stiffness and damping model is used. The effects of the bearing clearance, external torque, and input speed on vibrations of the system are analyzed. The results show that vibrations of the ring gear and sun gear decrease with the increment of the external torque and increase with the increment of the input speed. Moreover, a reasonable bearing clearance can be helpful for reducing system vibrations for some mating external torque and input speed conditions. The results can provide some guidance to find new method to reduce vibrations and increase the service life of planetary gear systems.

Use of the Integrated Flexpin Bearing for Improving the Performance of Epicyclical Gear Systems

2003 ◽  
Author(s):  
Gerald P. Fox ◽  
Eric Jallat
Keyword(s):  
Power Density ◽  
Planetary Gear ◽  
Load Sharing ◽  
Contact Patterns ◽  
Length Direction ◽  
Gear Systems ◽  
Planetary Gear System ◽  
Gear Contact ◽  
Gear Drives ◽  
Deflected State

Epicyclical gear systems have typically been equipped with straddle-mounted planetary idlers having pins supported on the input and output sides of the carrier. Torsional wind-up of the carrier, position accuracy of the pins, machining tolerances of the planetary gear system components and bearings clearances can all contribute to a poor load sharing among the planetary idlers as well as misaligned gear contacts in the deflected state. Use of the double-cantilevered flexible pin concept to achieve better load sharing and gear contact patterns among a multiplicity of planetary idlers, has been used to improve reliability in advanced gear drives for many years. The consequence of this practice is to build a compliant epicyclical system that improves power density in the gear length direction because the probability of achieving a properly centered gear contact is increased. The Integrated Flexpin Bearing, the subject of this paper, is capable of achieving additional power density in the gear diameter direction through integration of bearing components, gearing and shafting. This paper presents one designer’s approach to optimizing an Integrated Flexpin Bearing to improve the reliability of an epicyclical gearbox.

Understanding Vibration Spectra of Planetary Gear Systems for Fault Detection

2003 ◽  
Author(s):  
Marianne Mosher
Keyword(s):  
Fault Detection ◽  
Kinematic Model ◽  
Planetary Gear ◽  
Model Data ◽  
Vibration Measurements ◽  
Flight Data ◽  
Vibration Spectra ◽  
Gear Mesh ◽  
Gear Systems ◽  
Made In

This paper explores the vibration spectra for planetary gear systems by studying a kinematic model of vibration and comparing the model with measurements of two helicopter transmissions made in flight. The model and flight data include systems with both uniformly and nonuniformly spaced planet gears. This model predicts vibration to occur only at frequencies that are integer multiples of the planet spacing repetition frequency and clustered around gear mesh harmonics. Vibration measurements show the model correctly predicts the frequencies with large components around the first several harmonics of the gear mesh frequency. Measurements do not confirm some of the more detailed features predicted by the model. Some features in the spectra from the numerically derived model can be used to separate the model data with and without planted faults. These features were not found useful for detecting faults in the vibration measurements of real gearboxes in flight due to added complexity in the spectra from real gearboxes.

Detection of Carrier-Plate Cracks Using Vibration Spectra

2007 ◽  
Author(s):  
Romano Patrick ◽  
Al Ferri ◽  
George Vachtsevanos
Keyword(s):  
Experimental Data ◽  
Mathematical Analysis ◽  
Planetary Gear ◽  
Vibration Signals ◽  
Vibration Spectra ◽  
Vibration Sensors ◽  
Vibration Signature ◽  
Frequency Components ◽  
Planet Gear ◽  
Gear Systems

This paper examines the problem of identifying cracks in planetary gear systems through use of vibration sensors on the stationary gearbox housing. In particular, the effect of unequal spacing of planet gears relative to the rotating carrier plate on various frequency components in the vibration spectra is studied. The mathematical analysis is validated with experimental data comparing the vibration signature of helicopter transmissions operating either normally or with damage leading to shifts in the planet gear positions. The theory presented is able to explain certain features and trends in the measured vibration signals of healthy and faulty transmissions. The characterization offered may serve as a means of detecting damage in planetary gear systems.

scholarly journals Vibration Characteristics Analysis of Planetary Gears with a Multi-Clearance Coupling in Space Mechanism

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2687 ◽  
Author(s):  
Huibo Zhang ◽  
Chaoqun Qi ◽  
Jizhuang Fan ◽  
Shijie Dai ◽  
Bindi You
Keyword(s):  
Rotational Velocity ◽  
Dynamic Performance ◽  
Planetary Gear ◽  
Vibration Characteristics ◽  
Radial Clearance ◽  
Nonlinear Dynamic Model ◽  
Planetary Gears ◽  
Light Load ◽  
Characteristics Analysis ◽  
Gear Systems

Multi-clearance is the main cause for the performance and reliability decline of complicated mechanical systems. The increased clearance could induce contacts and impacts in joints, and consequently affect control accuracy. A nonlinear dynamic model of planetary gears with multi-clearance coupling is proposed in the current study to investigate the mechanism of influence of clearance on the dynamic performance. In addition, the coupling relationship between radial clearance and backlash is integrated into the multi-body system dynamics. The vibration characteristics of planetary gears with the changes of rotational velocity, clearance size and inertia load are explored. The numerical simulation results show that there are complex coupling relations in planetary gear systems, due to the multi-clearance coupling. The phenomenon of system resonance may occur with the changes of rotational velocities and clearances’ sizes. Multi-clearance coupling can significantly increase the resonant response of planetary gear systems in empty-load or light-load states.

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