multi stage planetary gearbox

With single spur gears, a pair of gears forms a gear stage. If you connect several gear pairs one after another, this is known as a multi-stage gearbox. For each gear stage, the path of rotation between your drive shaft and the result shaft is usually reversed. The entire multiplication aspect of multi-stage gearboxes is calculated by multiplying the ratio of every gear stage.
The drive speed is reduced or increased by the factor of the gear ratio, depending on whether it is a ratio to slow or a ratio to fast. In the majority of applications ratio to sluggish is required, because the drive torque is multiplied by the overall multiplication factor, unlike the drive rate.
A multi-stage spur gear can be realized in a technically meaningful method up to a gear ratio of around 10:1. The reason behind this lies in the ratio of the number of teeth. From a ratio of 10:1 the traveling gearwheel is extremely little. This has a poor influence on the tooth geometry and the torque that’s becoming transmitted. With planetary gears a multi-stage gearbox is extremely easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by simply increasing the space of the ring gear and with serial arrangement of many individual planet levels. A planetary equipment with a ratio of 20:1 could be manufactured from the individual ratios of 5:1 and 4:1, for example. Instead of the drive shaft the planetary carrier provides the sun equipment, which drives the next planet stage. A three-stage gearbox can be obtained through increasing the distance of the ring gear and adding another world stage. A transmitting ratio of 100:1 is obtained using person ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios could be combined, which results in a big number of ratio choices for multi-stage planetary gearboxes. The transmittable torque can be increased using extra planetary gears when performing this. The path of rotation of the drive shaft and the output shaft is often the same, so long as the ring equipment or housing is fixed.
As the amount of gear stages increases, the efficiency of the entire gearbox is reduced. With a ratio of 100:1 the efficiency is lower than with a ratio of 20:1. In order to counteract this scenario, the actual fact that the power loss of the drive stage is low must be taken into account when working with multi-stage gearboxes. This is achieved by reducing gearbox seal friction multi stage planetary gearbox reduction or having a drive stage that is geometrically smaller, for example. This also decreases the mass inertia, which is usually advantageous in powerful applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes can also be realized by combining different types of teeth. With a right position gearbox a bevel equipment and a planetary gearbox are simply just combined. Here too the entire multiplication factor may be the product of the individual ratios. Depending on the type of gearing and the type of bevel equipment stage, the drive and the output can rotate in the same path.
Benefits of multi-stage gearboxes:
Wide range of ratios
Constant concentricity with planetary gears
Compact design with high transmission ratios
Combination of different gearbox types possible
Wide variety of uses
Disadvantages of multi-stage gearboxes (compared to single-stage gearboxes):
More complex design
Lower degree of efficiency
The automatic transmission system is quite crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a typical feature. With the upsurge in design intricacies of planetary gearbox, mathematical modelling has become complex in character and therefore there is a dependence on modelling of multistage planetary gearbox including the shifting scheme. A random search-centered synthesis of three levels of freedom (DOF) high-rate planetary gearbox provides been presented in this paper, which derives an efficient gear shifting mechanism through designing the transmission schematic of eight rate gearboxes compounded with four planetary gear sets. Furthermore, by using lever analogy, the tranny power circulation and relative power effectiveness have been motivated to analyse the gearbox design. A simulation-based screening and validation have been performed which display the proposed model is effective and produces satisfactory change quality through better torque features while shifting the gears. A new heuristic method to determine ideal compounding arrangement, predicated on mechanism enumeration, for developing a gearbox layout is proposed here.
Multi-stage planetary gears are widely used in many applications such as automobiles, helicopters and tunneling boring machine (TBM) due to their benefits of high power density and large reduction in a small quantity [1]. The vibration and noise problems of multi-stage planetary gears are always the focus of attention by both academics and engineers [2].
The vibration of simple, single-stage planetary gears has been studied by many researchers. In the early literatures [3-5], the vibration structure of some example planetary gears are identified using lumped-parameter models, however they didn’t give general conclusions. Lin and Parker [6-7] formally determined and proved the vibration framework of planetary gears with equal/unequal planet spacing. They analytically classified all planetary gears modes into exactly three categories, rotational, translational, and planet settings. Parker [8] also investigated the clustering phenomenon of the three mode types. In the recent literatures, the systematic classification of settings had been carried into systems modeled with an elastic continuum ring equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high quickness gears with gyroscopic effects [12].
The organic frequencies and vibration modes of multi-stage planetary gears also have received attention. Kahraman [13] established a family of torsional dynamics models for compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general description including translational levels of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal features of substance planetary gears had been analogous to a simple, single-stage planetary gear system. Meanwhile, there are various researchers concentrating on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as TBM [15] and wind turbine [16].
Based on the aforementioned versions and vibration framework of planetary gears, many experts worried the sensitivity of the natural frequencies and vibration settings to program parameters. They investigated the effect of modal parameters such as tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary equipment natural frequencies and vibration modes [17-19]. Parker et al. [20-21] mathematically analyzed the effects of style parameters on natural frequencies and vibration modes both for the single-stage and compound planetary gears. They proposed closed-form expressions for the eigensensitivities to model parameter variants according to the well-defined vibration setting properties, and founded the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They utilized the organized vibration modes to show that eigenvalue loci of different setting types often cross and those of the same setting type veer as a model parameter is certainly varied.
However, the majority of of the existing studies only referenced the method used for single-stage planetary gears to investigate the modal features of multi-stage planetary gears, while the differences between these two types of planetary gears were ignored. Because of the multiple degrees of freedom in multi-stage planetary gears, more detailed division of organic frequencies must analyze the impact of different system parameters. The aim of this paper can be to propose a novel method of examining the coupled modes in multi-stage planetary gears to analyze the parameter sensitivities. Purely rotational degree of freedom models are used to simplify the analytical investigation of gear vibration while keeping the primary dynamic behavior generated by tooth mesh forces. In this paper, sensitivity of natural frequencies and vibration modes to both gear parameters and coupling shaft parameters of multi-stage planetary gears are studied.
1. Planetary gear sets are available in wide reduction gear ratios
2. Gear established can combine the same or different ratios
3. Planetary gear set is available in plastic, sintered metallic, and steel, based on different application
4. Hight efficiency: 98% efficiency at single reduction, 95% at double reduction
5. Planetary gear set torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, result shafts
The planetary equipment is a special kind of gear drive, where the multiple world gears revolve around a centrally arranged sunlight gear. The planet gears are installed on a planet carrier and engage positively in an internally toothed ring equipment. Torque and power are distributed among many planet gears. Sun equipment, planet carrier and band gear may either be traveling, driven or fixed. Planetary gears are found in automotive building and shipbuilding, aswell as for stationary use in turbines and general mechanical engineering.
The GL 212 unit allows the investigation of the powerful behaviour of a two-stage planetary gear. The trainer contains two planet gear pieces, each with three planet gears. The ring equipment of the initial stage can be coupled to the planet carrier of the next stage. By fixing individual gears, it is possible to configure a complete of four different tranny ratios. The apparatus is accelerated with a cable drum and a adjustable set of weights. The group of weights is elevated with a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight provides been released. The weight is usually caught by a shock absorber. A transparent protective cover prevents accidental contact with the rotating parts.
In order to determine the effective torques, the drive measurement measures the deflection of bending beams. Inductive rate sensors on all drive gears allow the speeds to be measured. The measured ideals are transmitted right to a PC via USB. The data acquisition software is roofed. The angular acceleration can be read from the diagrams. Effective mass moments of inertia are dependant on the angular acceleration.
investigation of the dynamic behaviour of a 2-stage planetary gear
three world gears per stage
four different transmission ratios possible
gear is accelerated via cable drum and variable set of weights
weight raised by hand crank; ratchet prevents accidental release
clamping roller freewheel enables free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
power measurement on different equipment phases via 3 bending pubs, display via dial gauges
inductive speed sensors
GUNT software program for data acquisition via USB under Windows 7, 8.1, 10
Technical data
2-stage planetary gear
module: 2mm
sun gears: 24-tooth, d-pitch circle: 48mm
planet gears: 24-tooth, d-pitch circle: 48mm
band gears: 72-tooth, d-pitch circle: 144mm
Drive
set of weights: 5…50kg
max. potential energy: 245,3Nm
Load at standstill
weight forces: 5…70N
Measuring ranges
speed: 0…2000min-1
230V, 50Hz, 1 phase
230V, 60Hz, 1 stage; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic type of planetary gearing involves three sets of gears with different degrees of freedom. World gears rotate around axes that revolve around a sun gear, which spins in place. A ring equipment binds the planets on the outside and is completely fixed. The concentricity of the planet grouping with sunlight and ring gears means that the torque bears through a straight range. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not merely decreases space, it eliminates the necessity to redirect the power or relocate other parts.
In a straightforward planetary setup, input power turns the sun gear at high quickness. The planets, spaced around the central axis of rotation, mesh with the sun as well as the fixed ring gear, so they are forced to orbit as they roll. All the planets are mounted to a single rotating member, called a cage, arm, or carrier. As the earth carrier turns, it provides low-speed, high-torque output.
A fixed component isn’t constantly essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single result driven by two inputs, or an individual input traveling two outputs. For instance, the differential that drives the axle in an automobile can be planetary bevel gearing – the wheel speeds represent two outputs, which must differ to take care of corners. Bevel equipment planetary systems operate along the same principle as parallel-shaft systems.
Even a simple planetary gear train has two inputs; an anchored ring gear represents a constant insight of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (as opposed to basic) planetary trains have at least two planet gears attached in collection to the same shaft, rotating and orbiting at the same speed while meshing with different gears. Compounded planets can have different tooth numbers, as can the gears they mesh with. Having this kind of options greatly expands the mechanical options, and allows more decrease per stage. Compound planetary trains can easily be configured so the planet carrier shaft drives at high speed, while the reduction issues from sunlight shaft, if the designer prefers this. Another thing about substance planetary systems: the planets can mesh with (and revolve around) both set and rotating external gears simultaneously, therefore a ring gear isn’t essential.
Planet gears, for his or her size, engage a whole lot of teeth as they circle the sun equipment – therefore they can easily accommodate several turns of the driver for each output shaft revolution. To perform a comparable reduction between a standard pinion and equipment, a sizable gear will need to mesh with a fairly small pinion.
Basic planetary gears generally provide reductions as high as 10:1. Substance planetary systems, which are far more elaborate than the simple versions, can offer reductions often higher. There are apparent ways to further reduce (or as the case could be, increase) quickness, such as for example connecting planetary phases in series. The rotational result of the first stage is from the input of another, and the multiple of the individual ratios represents the final reduction.
Another option is to introduce regular gear reducers into a planetary train. For instance, the high-quickness power might pass through an ordinary fixedaxis pinion-and-gear set before the planetary reducer. Such a configuration, known as a hybrid, is sometimes favored as a simplistic alternative to additional planetary levels, or to lower insight speeds that are too much for some planetary units to take care of. It also has an offset between the input and result. If the right angle is necessary, bevel or hypoid gears are occasionally attached to an inline planetary system. Worm and planetary combinations are uncommon since the worm reducer by itself delivers such high changes in speed.

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