一种消象旋传动机构的设计与精度分析

本文提出了一种消象旋机构的结构形式.并对齿轮传动的结构方式做了重点介绍.通过对齿轮传动进行精度分析,可以得出传动过程中齿轮精度及传动误差对棱镜消旋系统正象精度的影响.     

A new method for testing polymer gear wear rate and performance

This paper provides details of a new test rig design and methodology intended for, and successfully applied to, measuring the gear wear rate and performance of polymer composite gears under both dry and lubricated conditions. One of its unique contributions is that it continuously measures the gear wear rate, a feature essential for understanding polymer gear behaviour. While sharing some concepts with the traditional back-to-back test configuration used for steel gears, the new method introduces a rotary freedom to the block supporting the polymer gears under test. This block rotates if the gear tooth thickness is reduced, which aids control of the test load. The gear surface wear rate is recorded continuously by using a capacitance transducer to measure the pivot block motion. A second unique contribution of the new test method involves splitting the support block so that controlled misaligned gear engagements (not reported in other designs) can be introduced and subsequent changes to wear behaviour studied. The paper first outlines the test rig concepts and design before discussing in more detail the gear wear rate measuring principles, the methods of centre distance adjustment and the achievement of virtually constant gear loading. Finally, a selection test results are presented in summary to further validate the new test method and illustrate potential applications.     

Prediction of airborne radiated noise from lightly loaded lubricated meshing gear teeth

This paper introduces a novel analytical method for determination of gear airborne noise under lightly loaded conditions, often promoting gear rattle of loose unengaged gear pairs. The system examined comprises a single gear pair, modelled through integrated contact tribology and inertial transient dynamics. Lubricant film thickness, structural vibration and airborne gear noise are predicted and correlated with experimental measurements undertaken in a semi-anechoic environment. Good agreement is noticed between the numerical predictions and the experimental measurements. The presented model is capable of estimating the airborne radiated gear noise levels and the dynamic behaviour of gear pairs under different operating conditions, with superimposed impulsive input speed harmonics.     

Experimental study of gear rattle excited by a multi-harmonic excitation

This paper deals with the rattle noise, caused by the fluctuations of the engine torque (acyclic excitation) which, under special conditions, can cause multiple impacts inside the gearbox. Its aim is to experimentally describe the rattle phenomenon in a gearbox. First, a fully instrumented test rig consisting of a simplified gearbox was designed in order to recreate the rattle noise phenomenon for a multi harmonic excitation imposed to the input shaft of the gearbox. Second, different gearbox configurations were used to characterize the rattle threshold and the rattle noise evolution, in relation to excitation parameters and mechanical gearbox parameters. Third, a simplified model of the rattle phenomenon is drawn, using a Kelvin-Voigt model, aiming to determine the most significant parameters influencing the rattle noise.     

Experimental study of dynamic and noise produced by a gearing excited by a multi-harmonic excitation

This paper deals with the rattle noise, caused by the fluctuation of the engine torque (acyclic excitation) which, under special conditions, can cause multiple impacts inside the gearbox. Its aim is to experimentally describe the rattle phenomenon in a gearbox. First, a fully instrumented test rig consisting of a simplified gearbox was designed in order to recreate the rattle noise phenomenon for a multi harmonic excitation imposed to the input shaft of the gearbox. Second, different gearbox configurations were used to characterize the rattle threshold and the rattle noise evolution, in relation to excitation parameters and mechanical gearbox parameters. Third, a simplified model of the rattle phenomenon is drawn, aiming to determine the most significant parameters to the rattle noise.     

Preparation and microstructure characteristics of low-temperature bainite in surface layer of low carbon gear steel

A kind of technology was proposed for the development of low-temperature bainitic microstructure in the surface layer of low-carbon gear steel 20CrMnMo, which is based on carburization and succedent low-temperature austempering. The carbon content in the surface carburization layer increases to 0.81 wt.%, making the martensite starting point depressed. Low-temperature bainite formed in the carburization layer and lath martensite with low carbon content in the center by austempering at a low temperature slightly higher than the martensite starting point of the surface layer. Aluminum is added as alloying elements with the purpose of enhancing the driving force of bainitic transformation and retarding the precipitation of cementite during austempering. With the excellent toughness of low-temperature bainite, this low-temperature austempering technology could be a potential substitute of the traditional quenching and tempering heat treatment in the manufacture of gear.     

Identification and control of chaos in nonlinear gear dynamic systems using Melnikov analysis

In this paper, the Melnikov analysis is extended to develop a practical model of gear system to control and eliminate the chaotic behavior. To this end, a nonlinear dynamic model of a spur gear pair with backlash, time-varying stiffness and static transmission error is established. Based on the Melnikov analysis the global homoclinic bifurcation and transition to chaos in this model are predicted. Then non-feedback control method is used to eliminate the chaos by applying an additional control excitation. The regions of the parameter space for the control excitation are obtained analytically. The accuracy of the theoretical predictions and also the performance of the proposed control system are verified by the comparison with the numerical simulations. The simulation results show effectiveness of the proposed control system and present some useful information to analyze and control the gear dynamical systems.     

Influence of nonlinear stiffness of teeth on dynamic loads in gear transmission

In this paper the influence of the nonlinear stiffness of mating gear teeth on dynamic loads occurring between teeth in a single gear transmission is investigated using a discrete-continuous model consisting of two ponderable shafts torsionally deformed and four rigid bodies. The influence of a weak nonlinearity is discussed for a soft and a hard characteristics of mating gear teeth. Considerations are performed by means of the wave method which enables nonlinear dynamic loads in steady as well as in transient states to be determined.

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Sommario L'influenza della rigidezza nonlineare di ruote dentate sui carichi dinamici presenti tra i denti di una singola trasmissione a ruote, viene analizzata usando il modello discreto-continuo formato da due alberi ponderabili torsionalmente deformati e quattro corpi rigidi. L'influenza di una debole nonlinearità viene discussa per una caratteristica debole ed una forte di ruote dentate. Vengono fatte alcune considerazioni per mezzo del metodo delle onde che permette di determinare i carichi dinamici nonlineari sia negli stati stazionari che in quelli transitori.

     

Optimisation de la forme de la trochoïde dans un engrenage droitOptimization of the trochoid form in spur wheels

Generally, mechanical damage in gear wheels results from either cracks at the base of the tooth or from high contact pressure between the teeth.Starting from the principle of mass minimization, this Note develops a new formulation in terms of displacement, calling on a new, more resistant and less voluminous form for the base of the teeth. As a result, the first cause of the breakages which happen at this point because of a concentration of constraints are limited. To cite this article: M.E.H. Bouanane, M. Bouchama, C. R. Mecanique 331 (2003).     

On Gear Modelling in Multistage Rotary Vane Engines

A discussion of the dynamics of a multistage rotary vane engine is given in terms of a simplified model for combustion driving torques, power dissipation, and torque transmission. Torque transmission is effected by conjugate gear pairs attached to each unit of the engine. An argument for the design of such pairs is presented so that unwanted torque fluctuations in a flywheel attached to a member of the pair can be significantly attenuated. It is suggested that a variant of simple Cosserat dynamics offers a useful modelling tool for discussing the complex interaction between interacting gear teeth. A quasi-stationary analysis is used to place bounds of a particular choice of conjugate gear coupling in the presence of such interactions. It is concluded that a multistage rotary vane engine with at least two units can be usefully coupled to a single flywheel via a well-defined conjugate gear system that attenuates unwanted torque fluctuations over a broad range of rotary speeds.