With single spur gears, a couple of gears forms a gear stage. In the event that you connect several gear pairs one after another, that is referred to as a multi-stage gearbox. For every gear stage, the path of rotation between your drive shaft and the output shaft is usually reversed. The entire multiplication aspect 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 slower is required, because the drive torque is 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 gear ratio of around 10:1. The reason for this lies in the ratio of the amount of the teeth. From a ratio of 10:1 the traveling gearwheel is extremely small. This has a poor influence on the tooth geometry and the torque that’s becoming transmitted. With planetary gears a multi-stage gearbox is incredibly easy to realize.
A two-stage gearbox or a three-stage gearbox can be achieved by simply increasing the length of the ring equipment and with serial arrangement of a number of individual planet levels. A planetary equipment with a ratio of 20:1 can be manufactured from the average person ratios of 5:1 and 4:1, for instance. Rather than the drive shaft the planetary carrier provides the sun gear, which drives the following world stage. A three-stage gearbox is obtained by means of increasing the distance of the ring gear and adding another world stage. A transmission 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 outcomes in a big number of ratio choices for multi-stage planetary gearboxes. The transmittable torque could be increased using additional planetary gears when carrying out this. The direction of rotation of the drive shaft and the output shaft is always the same, provided that the ring equipment or casing is fixed.
As the number of gear stages increases, the efficiency of the overall gearbox is decreased. With a ratio of 100:1 the effectiveness is multi stage planetary gearbox leaner than with a ratio of 20:1. In order to counteract this circumstance, the fact that the power loss of the drive stage is definitely low must be taken into factor when working with multi-stage gearboxes. That is attained by reducing gearbox seal friction reduction or having a drive stage that’s geometrically smaller, for instance. This also decreases the mass inertia, which is usually advantageous in powerful applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes may also be realized by combining various kinds of teeth. With the right position gearbox a bevel gear and a planetary gearbox are simply just combined. Here too the overall multiplication factor may be the product of the average person ratios. Depending on the type of gearing and the kind of bevel equipment stage, the drive and the output can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide variety of ratios
Constant concentricity with planetary gears
Compact design with high transmission ratios
Mix of different gearbox types possible
Wide range of uses
Disadvantages of multi-stage gearboxes (in comparison to single-stage gearboxes):
More complex design
Lower amount of efficiency
The automated transmission system is quite crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a typical feature. With the increase in style intricacies of planetary gearbox, mathematical modelling is becoming complex in character and therefore there is a need for modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three examples of freedom (DOF) high-acceleration planetary gearbox offers been shown in this paper, which derives a competent gear shifting mechanism through designing the tranny schematic of eight rate gearboxes compounded with four planetary equipment sets. Furthermore, by making use of lever analogy, the transmitting power circulation and relative power effectiveness have been motivated to analyse the gearbox design. A simulation-based assessment and validation have already been performed which show the proposed model is certainly efficient and produces satisfactory shift quality through better torque characteristics while shifting the gears. A new heuristic solution to determine ideal compounding arrangement, predicated on mechanism enumeration, for developing a gearbox design is proposed here.
Multi-stage planetary gears are trusted in many applications such as automobiles, helicopters and tunneling boring machine (TBM) due to their advantages of high power density and huge reduction in a little 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, but they didn’t provide general conclusions. Lin and Parker [6-7] formally discovered and proved the vibration structure of planetary gears with equivalent/unequal world spacing. They analytically classified all planetary gears settings into exactly three classes, rotational, translational, and planet settings. Parker [8] also investigated the clustering phenomenon of the three mode types. In the latest literatures, the systematic classification of settings were carried into systems modeled with an elastic continuum band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high speed gears with gyroscopic effects [12].
The natural frequencies and vibration settings of multi-stage planetary gears have also received attention. Kahraman [13] set up a family group of torsional dynamics models for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general explanation including translational examples of freedom, which enables an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears had been analogous to a simple, single-stage planetary gear program. 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].
According to the aforementioned models and vibration framework 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 tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary equipment natural frequencies and vibration settings [17-19]. Parker et al. [20-21] mathematically analyzed the effects of style 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 variations 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 gear eigenvalues. They utilized the structured vibration modes to show that eigenvalue loci of different setting types generally cross and the ones of the same setting type veer as a model parameter is certainly varied.
However, the majority of of the existing studies only referenced the technique used for single-stage planetary gears to analyze the modal features of multi-stage planetary gears, while the differences between both of these types of planetary gears were ignored. Due to the multiple examples of freedom in multi-stage planetary gears, more descriptive division of organic frequencies must analyze the influence of different system parameters. The aim 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 primary 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 arranged 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 reduction, 95% at double reduction
5. Planetary gear arranged torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, output shafts
The planetary gear is a special kind of gear drive, where the multiple world gears revolve around a centrally arranged sun gear. The earth gears are mounted on a planet carrier and engage positively in an internally toothed band gear. Torque and power are distributed among many planet gears. Sun equipment, planet carrier and ring equipment may either be generating, driven or set. Planetary gears are found in automotive building and shipbuilding, as well as for stationary make use of 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 consists of two planet gear pieces, each with three planet gears. The ring equipment of the first stage can be coupled to the earth carrier of the next stage. By fixing person gears, it is possible to configure a complete of four different transmitting ratios. The gear is accelerated with a cable drum and a variable set of weights. The set of weights is raised with a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight has been released. The weight can be caught by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
In order to determine the effective torques, the force measurement measures the deflection of bending beams. Inductive rate sensors on all drive gears permit the speeds to become measured. The measured ideals are transmitted right to a Computer via USB. The info acquisition software is roofed. The angular acceleration could 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 adjustable set of weights
weight raised yourself crank; ratchet prevents accidental release
clamping roller freewheel allows free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
pressure measurement on different equipment phases 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
world 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 kind of planetary gearing involves three sets of gears with different levels of freedom. World gears rotate around axes that revolve around a sun gear, which spins set up. A ring gear binds the planets externally and is completely set. The concentricity of the earth grouping with sunlight and ring gears implies that the torque bears through a straight line. Many power trains are “comfortable” prearranged straight, and the lack of offset shafts not merely decreases space, it eliminates the need to redirect the energy or relocate other elements.
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 and also the fixed ring gear, 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 provides low-speed, high-torque output.
A fixed component isn’t generally essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output powered by two inputs, or a single input driving two outputs. For example, the differential that drives the axle in an vehicle 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.
A good simple planetary gear train has two inputs; an anchored ring gear represents a constant input of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (instead of basic) planetary trains have at least two planet gears attached in line to the same shaft, rotating and orbiting at the same rate while meshing with different gears. Compounded planets can have different tooth numbers, as can the gears they mesh with. Having such options significantly expands the mechanical opportunities, and allows more reduction per stage. Substance planetary trains can certainly be configured so the world carrier shaft drives at high acceleration, while the reduction issues from sunlight shaft, if the designer prefers this. One more thing about substance planetary systems: the planets can mesh with (and revolve around) both fixed and rotating exterior gears simultaneously, hence a ring gear is not essential.
Planet gears, for his or her size, engage a lot of teeth because they circle the sun gear – therefore they can certainly accommodate several turns of the driver for each result shaft revolution. To perform a comparable reduction between a typical pinion and gear, a sizable gear will have to mesh with a rather small pinion.
Simple planetary gears generally provide reductions as high as 10:1. Substance planetary systems, which are far more elaborate compared to the simple versions, can offer reductions often higher. There are apparent ways to further reduce (or as the case may be, increase) rate, such as for example 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 final reduction.
Another option is to introduce regular gear reducers into a planetary teach. For instance, the high-quickness power might go through an ordinary fixedaxis pinion-and-gear set before the planetary reducer. This kind of a configuration, called a hybrid, is sometimes favored as a simplistic option to additional planetary stages, or to lower insight speeds that are too high for some planetary units to take care of. It also has an offset between your input and result. If the right angle is needed, bevel or hypoid gears are occasionally attached to an inline planetary program. Worm and planetary combinations are rare since the worm reducer by itself delivers such high adjustments in speed.