multi stage planetary gearbox

With single spur gears, a set of gears forms a gear stage. If you connect several gear pairs one after another, that is known as a multi-stage gearbox. For every gear stage, the path of rotation between the drive shaft and the output shaft is definitely reversed. The entire multiplication element of multi-stage gearboxes is certainly calculated by multiplying the ratio of each gear stage.
The drive speed is reduced or increased by the factor of the apparatus ratio, depending on whether it is a ratio to gradual or a ratio to fast. In the majority of applications ratio to gradual is required, since the drive torque is certainly multiplied by the overall multiplication factor, unlike the drive velocity.
A multi-stage spur gear can be realized in a technically meaningful way up to gear ratio of around 10:1. The reason for this lies in the ratio of the number of tooth. From a ratio of 10:1 the generating gearwheel is extremely little. This has a negative effect on the tooth geometry and the torque that is being transmitted. With planetary gears a multi-stage gearbox is incredibly easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by basically increasing the length of the ring gear and with serial arrangement of several individual planet stages. A planetary gear with a ratio of 20:1 could be manufactured from the average person ratios of 5:1 and 4:1, for example. Instead of the drive shaft the planetary carrier provides the sun equipment, which drives the following planet stage. A three-stage gearbox is obtained through increasing the space of the ring equipment and adding another world stage. A tranny ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all person ratios can be combined, which results in a sizable number of ratio options for multi-stage planetary gearboxes. The transmittable torque can be increased using additional planetary gears when doing this. The path of rotation of the drive shaft and the result shaft is constantly 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 circumstance, the fact that the power loss of the drive stage can be low must be taken into thought when working with multi-stage gearboxes. That is attained by reducing gearbox seal friction loss or having a drive stage that is geometrically smaller, for instance. This also decreases the mass inertia, which can be advantageous in dynamic applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes can also be realized by combining various kinds of teeth. With a right angle gearbox a bevel equipment and a planetary gearbox are simply combined. Here as well the overall multiplication factor is the product of the individual ratios. Depending on the type of gearing and the type of bevel gear stage, the drive and the result can rotate in the same direction.
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 range of uses
Disadvantages of multi-stage gearboxes (compared to single-stage gearboxes):
More complex design
Lower amount of efficiency
The automatic transmission system is quite crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a standard feature. With the increase in style intricacies of planetary gearbox, mathematical modelling has become complex in nature and for that reason there is a dependence on modelling of multistage planetary gearbox including the shifting scheme. A random search-based synthesis of three degrees of freedom (DOF) high-quickness planetary gearbox offers been provided 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, with the help of lever analogy, the tranny power circulation and relative power effectiveness have been decided to analyse the gearbox style. A simulation-based tests and validation have already been performed which show the proposed model is certainly effective and produces satisfactory change quality through better torque characteristics while shifting the gears. A new heuristic method to determine ideal compounding arrangement, predicated on mechanism enumeration, for designing a gearbox layout is proposed here.
Multi-stage planetary gears are widely used in many applications such as for example 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 often the focus of interest by both academics and engineers [2].
The vibration of simple, single-stage planetary gears has been studied by many researchers. In the first literatures [3-5], the vibration framework of some example planetary gears are recognized using lumped-parameter models, but they didn’t give general conclusions. Lin and Parker [6-7] formally identified and proved the vibration structure of planetary gears with equal/unequal world spacing. They analytically categorized all planetary gears settings into exactly three classes, rotational, translational, and planet modes. Parker [8] also investigated the clustering phenomenon of the three mode types. In the latest literatures, the systematic classification of settings had been carried into systems modeled with an elastic continuum band equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high acceleration gears with gyroscopic results [12].
The natural frequencies and vibration modes of multi-stage planetary gears also have received attention. Kahraman [13] founded a family of torsional dynamics versions for compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of substance planetary gears of general description including translational examples of freedom, which multi stage planetary gearbox allows an infinite number of kinematic combinations. They mathematically proved that the modal features of compound planetary gears had been analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are plenty of researchers focusing 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 models and vibration framework of planetary gears, many experts concerned the sensitivity of the organic frequencies and vibration modes to program parameters. They investigated the result 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 design parameters on organic frequencies and vibration settings both for the single-stage and substance planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variations according to the well-defined vibration setting properties, and set up the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They utilized the organized vibration modes showing that eigenvalue loci of different setting types always cross and the ones of the same mode type veer as a model parameter can be varied.
However, the majority of of the current studies just referenced the technique used for single-stage planetary gears to analyze the modal features of multi-stage planetary gears, as the differences between these two types of planetary gears were ignored. Due to the multiple degrees of freedom in multi-stage planetary gears, more descriptive division of organic frequencies are required to analyze the influence of different system parameters. The aim of this paper is usually to propose an innovative way of analyzing the coupled settings in multi-stage planetary gears to analyze the parameter sensitivities. Purely rotational amount of freedom models are used to simplify the analytical investigation of equipment vibration while keeping the main dynamic behavior produced 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 set can combine the same or different ratios
3. Planetary gear set comes in plastic, sintered steel, and steel, depending 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 type of gear drive, in which the multiple planet gears revolve around a centrally arranged sun gear. The earth gears are installed on a world carrier and engage positively in an internally toothed ring gear. Torque and power are distributed among several planet gears. Sun gear, planet carrier and band equipment may either be driving, driven or fixed. Planetary gears are found in automotive structure and shipbuilding, as well as for stationary use in turbines and general mechanical engineering.
The GL 212 unit allows the investigation of the dynamic behaviour of a two-stage planetary gear. The trainer contains two planet gear units, each with three world gears. The ring equipment of the 1st stage is coupled to the earth carrier of the second stage. By fixing individual gears, you’ll be able to configure a total of four different tranny ratios. The gear is accelerated via a cable drum and a adjustable group of weights. The set 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 caught by a shock absorber. A transparent protective cover prevents accidental contact with the rotating parts.
In order to determine the effective torques, the pressure measurement measures the deflection of bending beams. Inductive velocity sensors on all drive gears permit the speeds to become measured. The measured ideals are transmitted right to a Personal computer via USB. The info acquisition software is included. The angular acceleration can be read from the diagrams. Effective mass occasions of inertia are dependant on the angular acceleration.
investigation of the powerful behaviour of a 2-stage planetary gear
three planet gears per stage
four different transmission ratios possible
equipment is accelerated via cable drum and variable set of weights
weight raised yourself crank; ratchet prevents accidental release
clamping roller freewheel enables free further rotation after the weight has been released
shock absorber for weight
transparent protective cover
drive measurement on different gear levels via 3 bending bars, display via dial gauges
inductive speed sensors
GUNT software 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
ring gears: 72-tooth, d-pitch circle: 144mm
Drive
group 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 phase; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic kind 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 gear binds the planets on the outside and is completely set. The concentricity of the planet grouping with sunlight and ring gears implies that the torque carries through a straight line. Many power trains are “comfortable” prearranged straight, and the absence of offset shafts not only reduces space, it eliminates the necessity to redirect the power or relocate other parts.
In a simple planetary setup, input power turns sunlight gear at high rate. The planets, spaced around the central axis of rotation, mesh with sunlight as well as the fixed ring gear, so they are forced to orbit as they roll. All the planets are mounted to an individual rotating member, called a cage, arm, or carrier. As the planet carrier turns, it delivers low-speed, high-torque output.
A set component isn’t often essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output powered by two inputs, or an individual input generating two outputs. For example, the differential that drives the axle in an car is certainly planetary bevel gearing – the wheel speeds represent two outputs, which must differ to take care of corners. Bevel gear planetary systems operate along the same principle as parallel-shaft systems.
Even a simple planetary gear train provides 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 world gears attached in range to the same shaft, rotating and orbiting at the same acceleration while meshing with different gears. Compounded planets can have got different tooth figures, as can the gears they mesh with. Having such options greatly expands the mechanical possibilities, and allows more reduction per stage. Compound planetary trains can simply be configured therefore the world carrier shaft drives at high acceleration, while the reduction issues from the sun shaft, if the designer prefers this. One more thing about substance planetary systems: the planets can mesh with (and revolve around) both set and rotating exterior gears simultaneously, therefore a ring gear isn’t essential.
Planet gears, because of their size, engage a lot of teeth as they circle the sun equipment – therefore they can simply accommodate numerous turns of the driver for every output shaft revolution. To perform a comparable decrease between a standard pinion and equipment, a sizable gear will need to mesh with a rather small pinion.
Basic planetary gears generally offer reductions as high as 10:1. Substance planetary systems, which are more elaborate compared to the simple versions, can offer reductions many times higher. There are apparent ways to further reduce (or as the case could be, increase) velocity, such as for example connecting planetary levels in series. The rotational output of the initial stage is linked to the input of another, and the multiple of the average person ratios represents the final reduction.
Another option is to introduce regular gear reducers into a planetary train. For instance, the high-velocity power might go through a typical fixedaxis pinion-and-gear set prior to the planetary reducer. This kind of a configuration, called a hybrid, is sometimes favored as a simplistic option to additional planetary phases, or to lower insight speeds that are too much for a few planetary units to take care of. It also provides an offset between your input and output. If the right angle is needed, bevel or hypoid gears are sometimes mounted on an inline planetary program. Worm and planetary combinations are rare since the worm reducer alone delivers such high changes in speed.

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