With single spur gears, a pair 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 direction of rotation between the drive shaft and the result shaft is usually reversed. The overall multiplication element of multi-stage gearboxes can be calculated by multiplying the ratio of each 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 nearly all applications ratio to slower is required, because the drive torque is definitely multiplied by the entire multiplication element, unlike the drive quickness.
A multi-stage spur gear can be realized in a technically meaningful method up to a gear ratio of approximately 10:1. The reason for this lies in the ratio of the number of the 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 is 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 merely increasing the distance of the ring gear and with serial arrangement of several individual planet phases. A planetary equipment 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 contains the sun equipment, which drives the next world stage. A three-stage gearbox is definitely obtained by way of increasing the length of the ring gear and adding another planet stage. A transmitting ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios can be combined, which outcomes in a huge number of ratio options for multi-stage planetary gearboxes. The transmittable torque could 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 equipment 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 low should be taken into concern when using multi-stage gearboxes. That is attained by reducing gearbox seal friction reduction or having a drive stage that is geometrically smaller, for instance. This also decreases the mass inertia, which is 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 angle gearbox a bevel equipment and a planetary gearbox are simply combined. Here too the overall multiplication factor is the product of the individual ratios. Depending on the kind 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 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 quite crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a standard feature. With the increase in style intricacies of planetary gearbox, mathematical modelling is becoming complex in character and for that reason there is a need for modelling of multistage planetary gearbox including the shifting scheme. A random search-based synthesis of three degrees of freedom (DOF) high-swiftness planetary gearbox provides been presented in this paper, which derives a competent gear shifting system through designing the transmission schematic of eight velocity gearboxes compounded with four planetary equipment sets. Furthermore, by making use of lever analogy, the tranny power circulation and relative power performance have been decided to analyse the gearbox design. A simulation-based examining and validation have already been performed which display the proposed model is definitely effective and produces satisfactory shift quality through better torque features while shifting the gears. A fresh heuristic solution to determine suitable compounding arrangement, based on mechanism enumeration, for developing a gearbox design 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 huge reduction in a small volume [1]. The vibration and noise problems of multi-stage planetary gears are generally 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, but they didn’t give general conclusions. Lin and Parker [6-7] formally determined and proved the vibration structure of planetary gears with equivalent/unequal planet spacing. They analytically classified all planetary gears modes into exactly three categories, rotational, translational, and world settings. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of settings had been carried into systems modeled with an elastic continuum ring gear [9], helical planetary gears [10], herringbone planetary gears [11], and high velocity gears with gyroscopic effects [12].
The organic frequencies and vibration settings 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 degrees of freedom, which enables an infinite number of kinematic combinations. They mathematically proved that the modal features of substance planetary gears were analogous to a simple, single-stage planetary gear program. Meanwhile, there are many researchers concentrating on the nonlinear dynamic characteristics of the multi-stage planetary gears for engineering applications, such as for example TBM [15] and wind mill [16].
According to the aforementioned versions and vibration structure of planetary gears, many researchers concerned the sensitivity of the natural 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 natural frequencies and vibration modes [17-19]. Parker et al. [20-21] mathematically analyzed the effects of design parameters on organic frequencies and vibration modes both for the single-stage and compound planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variants according to the well-defined vibration mode properties, and set up the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They utilized the structured vibration modes to show that eigenvalue loci of different mode types usually cross and those of the same setting 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 natural frequencies are required to analyze the impact of different system parameters. The objective of this paper is definitely to propose an innovative way of analyzing the coupled modes in multi-stage planetary gears to analyze the parameter sensitivities. Purely rotational degree of freedom models are accustomed to simplify the analytical investigation of equipment vibration while keeping the primary dynamic behavior generated by tooth mesh forces. In this paper, sensitivity of organic frequencies and vibration modes to both equipment 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 arranged 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 reduction, 95% at double reduction
5. Planetary gear arranged torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, result shafts
The planetary equipment is a special kind of gear drive, where the multiple planet gears revolve around a centrally arranged sun gear. The planet gears are installed on a world carrier and engage positively within an internally toothed ring gear. Torque and power are distributed among a number of planet gears. Sun equipment, planet carrier and band equipment may either be driving, driven or fixed. Planetary gears are used in automotive multi stage planetary gearbox 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 includes two planet gear units, each with three planet gears. The ring gear of the initial stage is definitely coupled to the planet carrier of the second stage. By fixing person gears, you’ll be able to configure a total of four different transmitting 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 helps prevent the weight from accidentally escaping. A clamping roller freewheel allows free further rotation following the weight offers been released. The weight is definitely caught by a shock absorber. A transparent protective cover prevents accidental connection with the rotating parts.
To be able to determine the effective torques, the pressure measurement measures the deflection of bending beams. Inductive acceleration sensors on all drive gears allow the speeds to become measured. The measured values are transmitted directly to a Computer via USB. The info acquisition software is roofed. The angular acceleration can be read from the diagrams. Effective mass occasions 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 after the weight has been released
shock absorber for weight
transparent protective cover
power measurement on different gear stages 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
sunlight 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 degrees 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 sunlight and ring gears means that the torque carries through a straight collection. Many power trains are “comfortable” prearranged straight, and the lack of offset shafts not merely reduces space, it eliminates the need to redirect the power or relocate other parts.
In a simple planetary setup, input power turns sunlight gear at high swiftness. The planets, spaced around the central axis of rotation, mesh with the sun and also the fixed ring equipment, so they are forced to orbit as they roll. All of the planets are installed to an individual rotating member, called a cage, arm, or carrier. As the earth carrier turns, it delivers low-speed, high-torque output.
A fixed component isn’t at all times essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single result powered by two inputs, or an individual input driving two outputs. For instance, the differential that drives the axle within an vehicle is planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel gear planetary systems operate along the same basic 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 move deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains have at least two world gears attached in range to the same shaft, rotating and orbiting at the same velocity while meshing with different gears. Compounded planets can have different tooth quantities, as can the gears they mesh with. Having such options greatly expands the mechanical options, and allows more reduction per stage. Substance planetary trains can easily be configured so the planet carrier shaft drives at high velocity, while the reduction problems from sunlight shaft, if the developer prefers this. One more thing about substance 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, for their size, engage a whole lot of teeth because 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 gear, a sizable gear will have to mesh with a rather small pinion.
Basic planetary gears generally provide reductions as high as 10:1. Compound planetary systems, which are far more elaborate compared to the simple versions, can provide reductions often higher. There are obvious ways to additional decrease (or as the case may be, increase) quickness, 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 individual ratios represents the ultimate reduction.
Another option is to introduce regular gear reducers into a planetary train. For instance, the high-rate power might go through an ordinary fixedaxis pinion-and-gear set before the planetary reducer. This kind of a configuration, known as a hybrid, is sometimes preferred as a simplistic option to additional planetary levels, or to lower insight speeds that are too high for some planetary units to handle. It also provides an offset between the input and result. 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.