With single spur gears, a pair of gears forms a gear stage. In the event that you connect several equipment 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 result shaft is definitely reversed. The overall multiplication element of multi-stage gearboxes is usually 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 sluggish is required, since the drive torque is usually multiplied by the overall multiplication element, unlike the drive velocity.
A multi-stage spur gear could be realized in a technically meaningful way up to gear ratio of around 10:1. The reason behind this lies in the ratio of the amount of tooth. From a ratio of 10:1 the traveling gearwheel is extremely little. This has a poor 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 can be achieved by merely increasing the length of the ring gear and with serial arrangement of several individual planet phases. A planetary gear with a ratio of 20:1 can 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 planet stage. A three-stage gearbox is definitely obtained through increasing the length of the ring equipment and adding another planet 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 results in a big number of ratio options 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 always the same, so long as the ring equipment or casing 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 leaner than with a ratio of 20:1. In order to counteract this scenario, the fact that the power lack of the drive stage can be low should be taken into thought when using multi-stage gearboxes. This is achieved by reducing gearbox seal friction reduction or having a drive stage that’s geometrically smaller, for instance. This also reduces the mass inertia, which is definitely advantageous in powerful applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes can 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 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 path.
Benefits of multi-stage gearboxes:
Wide variety of ratios
Constant concentricity with planetary gears
Compact style with high transmission ratios
Combination of different gearbox types possible
Wide variety of uses
Disadvantages of multi-stage gearboxes (compared to single-stage gearboxes):
More complex design
Lower degree of efficiency
The automatic transmission system is very crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a typical feature. With the increase in design intricacies of planetary gearbox, mathematical modelling has become complex in character and for that reason there is a need for modelling of multistage planetary gearbox including the shifting scheme. A random search-centered synthesis of three degrees of freedom (DOF) high-velocity planetary gearbox offers been presented in this paper, which derives a competent gear shifting mechanism through designing the transmission schematic of eight speed gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the transmitting power stream and relative power effectiveness have been established to analyse the gearbox style. A simulation-based examining and validation have been performed which show the proposed model is certainly efficient and produces satisfactory change quality through better torque features while shifting the gears. A new heuristic solution to determine ideal compounding arrangement, based on mechanism enumeration, for creating a gearbox design is proposed here.
Multi-stage planetary gears are widely used in many applications such as automobiles, helicopters and tunneling uninteresting machine (TBM) due to their benefits of high power density and huge reduction in a small volume [1]. The vibration and noise complications 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 discovered using lumped-parameter models, but they didn’t provide general conclusions. Lin and Parker [6-7] formally identified and proved the vibration framework of planetary gears with equal/unequal world spacing. They analytically classified 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 quickness gears with gyroscopic results [12].
The natural frequencies and vibration modes of multi-stage planetary gears have also received attention. Kahraman [13] established a family group of torsional dynamics versions for substance 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 allows thousands of kinematic combinations. They mathematically proved that the modal features of compound planetary gears were analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are numerous researchers focusing 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 versions and vibration framework of planetary gears, many researchers worried the sensitivity of the natural frequencies and vibration modes to system parameters. They investigated the effect of modal parameters such as tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary gear organic 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 substance planetary gears. They proposed closed-form expressions for the eigensensitivities to model parameter variants according to the well-defined vibration mode properties, and established 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 constantly cross and the ones of the same setting type veer as a model parameter can be varied.
However, many of the current studies only referenced the technique used for single-stage planetary gears to investigate the modal features of multi-stage planetary gears, while the differences between both of these types of planetary gears had been ignored. Due to the multiple examples of freedom in multi-stage planetary gears, more descriptive division of organic frequencies are required to analyze the impact of different system parameters. The objective of this paper is definitely to propose a novel method 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 gear 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 can be found in wide reduction gear ratios
2. Gear set can combine the same or different ratios
3. Planetary gear set comes in plastic, sintered metallic, and steel, based on different application
4. Hight efficiency: 98% efficiency at single reduction, 95% at double reduction
5. Planetary gear established torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, output shafts
The planetary equipment is a special kind of gear drive, in which the multiple planet gears revolve around a centrally arranged sun gear. The earth gears are mounted on a world carrier and engage positively in an internally toothed ring gear. Torque and power are distributed among a number of planet gears. Sun gear, planet carrier and ring equipment may either be traveling, driven or fixed. Planetary gears are used in automotive building and shipbuilding, aswell 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 sets, each with three world gears. The ring gear of the first stage is definitely coupled to the earth carrier of the next stage. By fixing individual gears, it is possible to configure a total of four different transmitting ratios. The gear is accelerated via a cable drum and a adjustable set of weights. The set of weights is elevated with a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel allows free further rotation following the weight provides been released. The weight is definitely caught by a shock absorber. A transparent protective cover helps prevent accidental contact 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 permit the speeds to end up being measured. The measured ideals are transmitted directly to a Personal computer via USB. The data acquisition software is roofed. The angular acceleration could be read from the diagrams. Effective mass occasions of inertia are determined by the angular acceleration.
investigation of the powerful 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 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 stages via 3 bending bars, display via dial gauges
inductive speed sensors
GUNT software program 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 stage; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic kind 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 in place. A ring equipment binds the planets on the outside and is completely fixed. The concentricity of the planet grouping with the sun and ring gears implies that the torque bears through a straight collection. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not merely reduces space, it eliminates the need to redirect the power or relocate other elements.
In a multi stage planetary gearbox simple planetary setup, input power turns the sun gear at high rate. 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 the planets are installed to an individual rotating member, known as a cage, arm, or carrier. As the planet carrier turns, it provides low-speed, high-torque output.
A set component isn’t at all times essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output powered by two inputs, or a single input generating two outputs. For instance, the differential that drives the axle in an vehicle is certainly planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel equipment planetary systems operate along the same basic principle as parallel-shaft systems.
Even a simple planetary gear train has two inputs; an anchored band gear represents a constant insight of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains possess at least two planet gears attached in collection to the same shaft, rotating and orbiting at the same speed while meshing with different gears. Compounded planets can possess different tooth quantities, as can the gears they mesh with. Having such options significantly expands the mechanical possibilities, and allows more decrease per stage. Compound planetary trains can certainly be configured so 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, because of their size, engage a lot of teeth as they circle the sun gear – therefore they can easily accommodate several turns of the driver for every result shaft revolution. To perform a comparable reduction between a standard pinion and gear, a sizable gear will need to mesh with a fairly small pinion.
Basic planetary gears generally offer reductions as high as 10:1. Compound planetary systems, which are more elaborate compared to the simple versions, can provide reductions many times higher. There are obvious ways to additional reduce (or as the case may be, increase) acceleration, such as for example connecting planetary stages in series. The rotational result of the 1st stage is linked to the input of the next, and the multiple of the individual ratios represents the final reduction.
Another option is to introduce standard gear reducers right into a planetary teach. For instance, the high-acceleration power might go through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, known as a hybrid, is sometimes preferred as a simplistic alternative to additional planetary stages, or to lower insight speeds that are too high for some planetary units to take care of. It also provides an offset between your input and result. If the right angle is necessary, bevel or hypoid gears are sometimes attached to an inline planetary program. Worm and planetary combinations are uncommon since the worm reducer by itself delivers such high adjustments in speed.