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, this is known as a multi-stage gearbox. For every gear stage, the path of rotation between the drive shaft and the output shaft is usually reversed. The overall multiplication factor of multi-stage gearboxes is usually calculated by multiplying the ratio of every gear stage.
The drive speed is reduced or increased by the factor of the apparatus ratio, depending on whether it is a ratio to slower or a ratio to fast. In nearly all applications ratio to gradual is required, since the drive torque is usually multiplied by the overall multiplication factor, unlike the drive acceleration.
A multi-stage spur gear could be realized in a technically meaningful method up to a gear ratio of approximately 10:1. The reason for this is based on the ratio of the number of teeth. From a ratio of 10:1 the traveling gearwheel is extremely small. This has a negative effect on the tooth geometry and the torque that’s getting 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 merely increasing the length of the ring equipment and with serial arrangement of several individual planet levels. A planetary gear 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 gear, which drives the next planet stage. A three-stage gearbox is definitely obtained by way of increasing the space of the ring equipment and adding another planet stage. A tranny ratio of 100:1 is obtained using person ratios of 5:1, 5:1 and 4:1. Basically, all person ratios could be combined, which results in a large number of ratio choices for multi-stage planetary gearboxes. The transmittable torque could be increased using additional planetary gears when performing this. The path of rotation of the drive shaft and the output shaft is generally the same, provided that the ring gear or housing is fixed.
As the number of gear stages increases, the efficiency of the overall gearbox is reduced. With a ratio of 100:1 the effectiveness is leaner than with a ratio of 20:1. In order to counteract this situation, the actual fact that the power loss of the drive stage is usually low must be taken into account when using 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 reduces the mass inertia, which is usually advantageous in powerful applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes can also be realized by combining different types of teeth. With a right angle gearbox a bevel equipment and a planetary gearbox are simply just combined. Here too the entire 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 variety of ratios
Constant concentricity with planetary gears
Compact style with high transmission ratios
Mix of different gearbox types possible
Wide variety of uses
Disadvantages of multi-stage gearboxes (in comparison to single-stage gearboxes):
More complex design
Lower amount of efficiency
The automatic transmission system is very 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 is becoming 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-velocity planetary gearbox has been shown in this paper, which derives a competent gear shifting system through designing the tranny schematic of eight swiftness gearboxes compounded with four planetary gear sets. Furthermore, by using lever analogy, the tranny power flow and relative power effectiveness have been decided to analyse the gearbox style. A simulation-based assessment and validation have already been performed which display the proposed model is effective and produces satisfactory shift quality through better torque features while shifting the gears. A fresh heuristic solution to determine ideal compounding arrangement, predicated on mechanism enumeration, for developing a gearbox design is proposed here.
Multi-stage planetary gears are widely used in many applications such as for example automobiles, helicopters and tunneling uninteresting machine (TBM) due to their advantages of high power density and huge reduction in a small volume [1]. The vibration and noise complications of multi-stage planetary gears are usually 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 structure of some example planetary gears are discovered using lumped-parameter models, however they didn’t provide general conclusions. Lin and Parker [6-7] formally determined and proved the vibration framework of planetary gears with equivalent/unequal planet spacing. They analytically categorized all planetary gears modes into exactly three groups, rotational, translational, and planet modes. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of modes were carried into systems modeled with an elastic continuum ring equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high acceleration gears with gyroscopic effects [12].
The natural frequencies and vibration settings of multi-stage planetary gears have also received attention. Kahraman [13] founded a family of torsional dynamics models for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic style of substance planetary gears of general explanation including translational degrees of freedom, which enables thousands 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 concentrating on the nonlinear dynamic features of the multi-stage planetary gears for engineering applications, such as TBM [15] and wind mill [16].
According to the aforementioned models and vibration framework of planetary gears, many experts concerned the sensitivity of the organic frequencies and vibration settings to system parameters. They investigated the effect of modal parameters such as for example tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary equipment organic 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 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 equipment eigenvalues. They used the structured vibration modes showing that eigenvalue loci of different mode types constantly cross and those of the same mode type veer as a model parameter is definitely varied.
However, many of the current studies just referenced the method 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. Because of the multi stage planetary gearbox multiple examples of freedom in multi-stage planetary gears, more descriptive division of organic frequencies are required to analyze the influence of different system parameters. The objective of this paper is usually to propose a novel method of examining the coupled settings 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 equipment parameters and coupling shaft parameters of multi-stage planetary gears are studied.
1. Planetary gear sets can be found in wide reduction gear ratios
2. Gear established can combine the same or different ratios
3. Planetary gear set is available in plastic, sintered metal, and steel, depending on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear set torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, output shafts
The planetary gear is a special type of gear drive, in which the multiple world gears revolve around a centrally arranged sunlight gear. The planet gears are installed on a world carrier and engage positively in an internally toothed band gear. Torque and power are distributed among many planet gears. Sun gear, planet carrier and band gear may either be driving, driven or fixed. Planetary gears are found in automotive construction 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 includes two planet gear models, each with three world gears. The ring gear of the 1st stage is definitely coupled to the earth carrier of the next stage. By fixing individual gears, it is possible to configure a complete of four different transmitting ratios. The gear is accelerated via a cable drum and a adjustable set of weights. The group of weights is raised via a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight has been released. The weight is usually caught by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
To be able to determine the effective torques, the push measurement measures the deflection of bending beams. Inductive velocity sensors on all drive gears allow the speeds to be measured. The measured ideals are transmitted directly to a Computer via USB. The info acquisition software is included. The angular acceleration can be read from the diagrams. Effective mass occasions of inertia are determined by the angular acceleration.
investigation of the dynamic behaviour of a 2-stage planetary gear
three world gears per stage
four different transmission ratios possible
equipment 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 after the weight has been released
shock absorber for weight
transparent protective cover
power measurement on different equipment stages via 3 bending pubs, 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 form of planetary gearing involves three sets of gears with different examples of freedom. World gears rotate around axes that revolve around a sunlight gear, which spins set up. A ring equipment binds the planets externally and is completely set. The concentricity of the planet grouping with the sun and ring gears means that the torque bears through a straight series. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not only reduces space, it eliminates the need to redirect the energy or relocate other elements.
In a simple planetary setup, input power turns the sun gear at high speed. The planets, spaced around the central axis of rotation, mesh with sunlight along with the fixed ring equipment, so they are pressured to orbit because they roll. All the planets are mounted to a single rotating member, called a cage, arm, or carrier. As the earth 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 result driven by two inputs, or an individual input driving two outputs. For instance, the differential that drives the axle within an car is certainly 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 basic principle as parallel-shaft systems.
Even a simple planetary gear train provides two inputs; an anchored band gear represents a constant input of zero angular velocity.
Designers can move deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains possess at least two planet gears attached in range to the same shaft, rotating and orbiting at the same rate while meshing with different gears. Compounded planets can possess different tooth quantities, as can the gears they mesh with. Having this kind of options significantly expands the mechanical options, and allows more decrease per stage. Substance planetary trains can easily be configured therefore the planet carrier shaft drives at high velocity, while the reduction issues from the sun shaft, if the developer prefers this. One more thing about compound planetary systems: the planets can mesh with (and revolve around) both fixed and rotating external gears simultaneously, therefore a ring gear isn’t essential.
Planet gears, for their size, engage a lot of teeth because they circle the sun gear – therefore they can simply accommodate several turns of the driver for each result shaft revolution. To execute a comparable decrease between a typical pinion and gear, a sizable gear will have to mesh with a fairly 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 often higher. There are apparent ways to further decrease (or as the case may be, increase) speed, such as for example connecting planetary levels in series. The rotational output of the initial stage is from the input of the next, and the multiple of the individual ratios represents the ultimate reduction.
Another option is to introduce regular gear reducers right into a planetary train. For instance, the high-rate power might go through a typical 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 levels, or to lower input speeds that are too high for a few planetary units to handle. It also provides an offset between the input and output. If a right angle is necessary, bevel or hypoid gears are sometimes mounted on an inline planetary system. Worm and planetary combinations are rare since the worm reducer alone delivers such high changes in speed.