With single spur gears, a couple of gears forms a gear stage. If you connect several equipment pairs one after another, this is referred to as a multi-stage gearbox. For every gear stage, the path of rotation between the drive shaft and the result shaft is definitely reversed. The overall multiplication element of multi-stage gearboxes is certainly 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 gradual or a ratio to fast. In nearly all applications ratio to gradual is required, since the drive torque is definitely multiplied by the overall multiplication element, unlike the drive speed.
A multi-stage spur gear can be realized in a technically meaningful method up to gear ratio of approximately 10:1. The reason for this is based on the ratio of the amount of teeth. From a ratio of 10:1 the traveling 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 simply increasing the length of the ring gear and with serial arrangement of several individual planet levels. 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 next world stage. A three-stage gearbox can be obtained through increasing the space of the ring gear and adding another world stage. A transmission ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios could be combined, which outcomes in a sizable number of ratio choices 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 often the same, provided that the ring equipment or casing is fixed.
As the amount of gear stages increases, the efficiency of the entire gearbox is decreased. With a ratio of 100:1 the effectiveness is lower than with a ratio of 20:1. To be able to counteract this situation, the fact that the power lack of the drive stage is definitely low should be taken into thought when working with multi-stage gearboxes. This is attained by reducing gearbox seal friction reduction or having a drive stage that’s 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 combined. Here too the overall multiplication factor may be the product of the average person ratios. Depending on the type of gearing and the type of bevel equipment stage, the drive and the output can rotate in the same direction.
Advantages 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 automated transmission system is quite crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a typical feature. With the upsurge in style intricacies of planetary gearbox, mathematical modelling has become complex in nature and for that reason there is a need for modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three degrees of freedom (DOF) high-quickness planetary gearbox provides been offered in this paper, which derives a competent gear shifting mechanism through designing the transmission schematic of eight velocity gearboxes compounded with four planetary equipment sets. Furthermore, with the help of lever analogy, the tranny power movement and relative power efficiency have been decided to analyse the gearbox style. A simulation-based testing and validation have been performed which show the proposed model is definitely effective and produces satisfactory shift quality through better torque features while shifting the gears. A new heuristic solution to determine suitable compounding arrangement, based 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) because of their benefits of high power density and large reduction in a small volume [1]. The vibration and noise complications of multi-stage planetary gears are always 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 early literatures [3-5], the vibration framework of some example planetary gears are identified using lumped-parameter models, but they didn’t provide general conclusions. Lin and Parker [6-7] formally discovered 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 world modes. Parker [8] also investigated the clustering phenomenon of the three mode types. In the recent literatures, the systematic classification of modes had been carried into systems modeled with an elastic continuum ring gear [9], helical planetary gears [10], herringbone planetary gears [11], and high speed 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 models for compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general description including translational examples of freedom, which allows an infinite number of kinematic combinations. They mathematically proved that the modal features of substance planetary gears were analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are several researchers concentrating on the nonlinear dynamic characteristics of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind turbine [16].
According to the aforementioned models and vibration structure of planetary gears, many researchers concerned the sensitivity of the natural frequencies and vibration settings to system parameters. They investigated the result of modal parameters such as for example tooth mesh stiffness, world bearing stiffness and support stiffness on planetary equipment natural frequencies and vibration modes [17-19]. Parker et al. [20-21] mathematically analyzed the consequences of style parameters on organic frequencies and vibration modes both for the single-stage and substance planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variants 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 to show that eigenvalue loci of different mode types constantly cross and the ones of the same mode type veer as a model parameter is varied.
However, most of the existing studies only referenced the method used for single-stage planetary gears to analyze the modal characteristics of multi-stage planetary gears, while the differences between these two types of planetary gears had been ignored. Because of the multiple levels of freedom in multi-stage planetary gears, more descriptive division of organic frequencies are required to analyze the impact of different program parameters. The objective of this paper can be to propose an innovative way of examining the coupled modes in multi-stage planetary gears to analyze the parameter sensitivities. Purely rotational amount of freedom models are accustomed to simplify the analytical investigation of equipment vibration while keeping the main 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 comes in plastic, sintered metallic, and steel, depending on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear arranged torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, output 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 planet carrier and engage positively in an internally toothed ring gear. Torque and power are distributed among many planet gears. Sun gear, planet carrier and band equipment may either be driving, driven or fixed. Planetary gears are found in automotive building and shipbuilding, aswell as for stationary make use of 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 models, each with three planet gears. The ring equipment of the first stage is usually coupled to the planet carrier of the next stage. By fixing person gears, you’ll be able to configure a complete of four different transmission ratios. The gear is accelerated via a cable drum and a adjustable group of weights. The group of weights is raised with a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight offers been released. The weight is certainly captured by a shock absorber. A transparent protective cover prevents accidental connection with the multi stage planetary gearbox rotating parts.
To be able to determine the effective torques, the pressure measurement measures the deflection of bending beams. Inductive swiftness sensors on all drive gears allow the speeds to end up being measured. The measured values are transmitted right to a PC via USB. The info acquisition software is roofed. The angular acceleration could 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
drive measurement on different gear stages via 3 bending bars, display via dial gauges
inductive speed sensors
GUNT software program for data acquisition via USB below 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 phase; 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 gear binds the planets on the outside and is completely set. The concentricity of the earth grouping with sunlight and ring gears means that the torque bears through a straight range. Many power trains are “comfortable” prearranged straight, and the absence of offset shafts not only reduces space, it eliminates the need to redirect the energy or relocate other parts.
In a simple planetary setup, input power turns sunlight gear at high quickness. The planets, spaced around the central axis of rotation, mesh with the sun and also the fixed ring gear, so they are forced to orbit as they roll. All of the planets are mounted to an individual rotating member, known as a cage, arm, or carrier. As the planet carrier turns, it delivers low-speed, high-torque output.
A set component isn’t always essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output powered by two inputs, or an individual input traveling two outputs. For instance, the differential that drives the axle in an vehicle is usually planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel gear planetary systems operate along the same principle as parallel-shaft systems.
Even a simple planetary gear train offers two inputs; an anchored ring gear represents a continuous insight of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains possess at least two planet gears attached in series to the same shaft, rotating and orbiting at the same rate while meshing with different gears. Compounded planets can possess different tooth numbers, as can the gears they mesh with. Having such options significantly expands the mechanical opportunities, and allows more decrease per stage. Compound planetary trains can easily be configured so the planet carrier shaft drives at high velocity, while the reduction problems from the sun shaft, if the designer prefers this. Another thing about compound planetary systems: the planets can mesh with (and revolve around) both set and rotating external gears simultaneously, hence a ring gear is not 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 each output shaft revolution. To perform a comparable reduction between a standard pinion and equipment, a sizable gear will need to mesh with a rather small pinion.
Basic planetary gears generally provide reductions as high as 10:1. Compound planetary systems, which are more elaborate compared to the simple versions, can provide reductions often higher. There are obvious ways to additional reduce (or as the case may be, increase) velocity, such as connecting planetary stages in series. The rotational output of the first stage is from the input of the next, and the multiple of the average person ratios represents the ultimate reduction.
Another choice is to introduce regular gear reducers into a planetary train. For example, the high-swiftness power might go through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. This kind of a configuration, known as a hybrid, is sometimes favored as a simplistic option to additional planetary stages, or to lower insight speeds that are too much for some planetary units to handle. It also provides an offset between your input and output. If a right angle is needed, bevel or hypoid gears are occasionally attached to an inline planetary system. Worm and planetary combinations are rare because the worm reducer by itself delivers such high changes in speed.