Design and experimental study of novel multi-stage gearbox

Automatic transmission has been widely used in the automotive industry, and novel automatic transmissions with simple structure and reliable operation are a research hotspot. This paper proposes an automatic transmission with multi-stage gears to simplify its working process. The automatic transmission comprises a case and a driving transmission shaft and driven shaft which are mounted on the case. The transmission gear pairs are superimposed on the driving and driven shafts similar to a tower. The gear pairs on the driving and driven shafts are always engaged. All the driving gears are connected to the driven shaft via a flat key, and the driven gear and the driven shaft are connected by a join key, which is used to connect or disconnect the gear and the driven shaft, and are controlled by a hydraulic shifting mechanism and have been designed in detail. Numerical simulation is adopted to verify the strength of the core components. In addition, the transmission performance of the gearbox is experimentally tested. The results indicate that the novel gearbox can achieve variable speed and work smoothly. The gearbox has a novel structure, the driving and driven shafts are simple and installed friendly, and the transmission gear meshes are reliable.

Whining noise computation of a planetary gear set induced by the multi-mesh excitations

A complete procedure for the whining noise computation of a planetary gear set induced by the multi-mesh excitations is presented. This procedure is divided into three main steps. First, the parametrical internal excitations are simultaneously characterized by considering all contacts at the multiple gear meshes. Secondly, a finite element model of the planetary gear set is built. Finally, the coupled equations of motion are projected onto the modal basis and the stationary dynamic response is computed using an iterative spectral method.

Down Angle Gearboxes – Calculation and Manufacturing Innovation for Low Noise Beveloid Gears

Conical involute gears, also known as beveloid gears, are used in marine gearboxes to provide an angle between the drive shaft and the output shaft. The axes of the beveloid gear meshes reviewed can be intersecting or skewed. Beveloid gears are a general case of spur gears with their virtual generating rack cutter tilted in the direction of feed. An appropriate variable addendum modification along the face width leads to conjugate flanks and therefore to tooth line contact. The elasticity of the gear mesh itself, the shafts, bearings and the gear housing cause deformations and deflections. Thus a tip relief at the generating tool in combination with flank modifications is applied to improve strength and transmission characteristics. Noise emission is reduced by comparing the level of dynamic excitation of different profile corrections. Strength calculations are done with local stresses, since there is no standardized nominal stress assessment. Theoretical evaluations are confirmed by prototype testing. This integrated designing procedure allows for an efficient planning and engineering for special beveloid gears. Several examples of application will be shown.

A Load Distribution Model for Planetary Gear Sets

A load distribution model of planetary gear sets presented is capable of simulating planetary gear sets having component- and system-level design variations such as component supporting conditions, different kinds of gear modifications and planetary gear sets with different numbers of equally or unequally spaced planets as well as different gear set kinematic configurations while considering gear mesh phasing. It also accounts for classes of planetary gear set manufacturing and assembly related errors associated with the carrier or gears, i.e., pinhole position errors, run-out errors, and tooth thickness errors. Example analyses are provided to indicate the need for a model of this type when studying load distribution of planetary gear sets due to unique loading of the gear meshes associated with planetary gear sets. Comparisons to measurements existing in the literature are provided.

Schwingungsinteraktion benachbarter Zahneingriffe*/Excitation behavior of adjacent gear meshes – Influence of interactions on rotational deviations in the drive train

Das Anregungsverhalten von Zahnradgetrieben mit Mehrfacheingriff, wie mehrstufige Getriebe und Räderketten, ist geprägt von Wechselwirkungen zwischen den Getriebestufen. Weisen die Getriebestufen identische Zahneingriffsfrequenzen auf, kann durch zeitliche Verschiebung der Eingriffsbeginne, genannt Phasenverschiebung, eine Reduktion der Rotationsabweichungen im Maschinenantrieb erzielt werden. Die optimale Wahl der Phasenverschiebung hängt vom Drehmoment und der Mikrogeometrie der Verzahnung ab.   The excitation behavior of gearboxes with multiple gear meshes, such as multi-stage gearboxes and gear chains, is characterized by interactions between the gear stages. If the gear stages have identical gear mesh frequencies, a reduction of the rotational deviations in the drive train can be achieved by temporally shifting the start of the gear mesh, called phase shift. The ideal choice of the phase shift depends on the torque at the operating point and the micro-geometry of the gear.

A Load Distribution Model for Planetary Gear Sets

Here, a load distribution model of planetary gear sets is presented capable of dealing with planetary gear sets with any component level and gear set level design variations such as component supporting conditions, different kinds of gear modifications and planetary gear sets with different numbers of equally or unequally spaced planets as well as different gear set kinematic configurations while considering gear mesh phasing. It also accounts for classes of planetary gear set manufacturing and assembly related errors associated with the carrier or gears, i.e. pinhole position errors, run-out errors and tooth thickness errors. Example analyses are provided to indicate the need for a model of this type when studying load distribution of planetary gear sets due to unique loading of the gear meshes associated with planetary gear sets. Comparisons to measurements existing in the literature are provided.

Dynamic meshing incentive analysis for wind turbine planetary gear system

Purpose Irregular windy loads are loaded for a wind turbine. This paper aims to determine the form of gear failure and the working life of the gear system by assessing the dynamic strength of gears and dynamic stress distribution. Design/methodology/approach The helical planetary gear system of the wind turbine growth rate gearbox was investigated, and while a variety of clearance and friction gear meshing processes were considered in the planetary gear system, a finite element model was built based on the contact–impact dynamics theory, solved using the explicit algorithm. The impact stress of the sun gear of the planetary gear system was calculated under different loads. An integrated planetary gear meshing stiffness, and the error of system dynamic transmission error were investigated when the planetary gear meshes with the sun or ring gears. Findings The load has little effect on the sun gear of the impact stress which was known. The varying stiffness is different while the planetary gear meshes with the sun and ring gears. There were differences between the planetary gear system and the planetary gear, and with load, the planetary gear transmission error decreases. Originality/value This study will provide basis knowledge for the planetary gear system.

Tooth modification for optimizing gear contact of a wind-turbine gearbox

This study investigates a method of calculating tooth modification amount of a wind-turbine gearbox. The requirements of high reliability and a service life of 20 years or longer for wind power gearboxes necessitate appropriate gear meshes, which require elaborate tooth modification. The interference between teeth caused by deformation of the gear body and the shaft alignment error, which is caused by deformation of system components such as the housing, the bearings, and the shaft, was calculated, and the result was used to determine the tooth modification parameters. Thus, a method of calculating tooth modification amount was developed that can be performed without trial and error; its reliability was confirmed by an evaluation through simulation. Contact was evenly distributed over the tooth surfaces after the tooth profile was corrected, thus improving the edge contact pattern relative to the situation before correction.

Optimization of Profile Modifications With Regard to Dynamic Tooth Loads in Single and Double-Helical Planetary Gears With Flexible Ring-Gears

This paper is mostly aimed at analyzing optimum profile modifications (PMs) in planetary gears (PGTs) with regard to dynamic mesh forces. To this end, a dynamic model is presented based on 3D two-node gear elements connected to deformable ring-gears discretized into beam elements. Double-helical gears are simulated as two gear elements of opposite hands which are linked by shaft elements. Symmetric tip relief on external and internal gear meshes are introduced as time-varying normal deviations along the lines of contact and time-varying mesh stiffness functions are deduced from Wrinckler foundation models. The equations of motion are solved by coupling a Newmark time-step integration scheme and a contact algorithm to account for possible partial or total contact losses. Symmetric linear PMs for helical and double-helical PGTs are optimized by using a genetic algorithm with the objective of minimizing dynamic tooth loads over a speed range. Finally, the sensitivity of these optimum PMs to speed and load is analyzed.