With single spur gears, a pair of gears forms a gear stage. In the event that you connect several gear pairs one after another, this is known as a multi-stage gearbox. For each gear stage, the path of rotation between your drive shaft and the output shaft is certainly reversed. The overall multiplication element of multi-stage gearboxes can be 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’s a ratio to slower or a ratio to fast. In nearly all applications ratio to gradual is required, since the drive torque is certainly multiplied by the overall multiplication element, unlike the drive acceleration.
A multi-stage spur gear can be realized in a technically meaningful method up to gear ratio of approximately 10:1. The reason behind this is based on the ratio of the number of teeth. From a ratio of 10:1 the generating gearwheel is extremely small. This has a poor influence on the tooth geometry and the torque that is being transmitted. With planetary gears a multi-stage gearbox is extremely easy to realize.
A two-stage gearbox or a three-stage gearbox can be achieved by just increasing the distance of the ring gear and with serial arrangement of many individual planet stages. A planetary equipment with a ratio of 20:1 can be manufactured from the average person ratios of 5:1 and 4:1, for example. Rather than the drive shaft the planetary carrier contains the sun gear, which drives the following planet stage. A three-stage gearbox is usually obtained by way of increasing the distance of the ring gear and adding another planet stage. A transmission ratio of 100:1 is obtained using individual 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 can be increased using extra planetary gears when carrying out this. The path of rotation of the drive shaft and the output shaft is always the same, provided that the ring gear or housing is fixed.
As the amount of equipment stages increases, the efficiency of the overall gearbox is reduced. With a ratio of 100:1 the performance is leaner than with a ratio of 20:1. In order 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 loss or having a drive stage that is geometrically smaller, for instance. This also reduces the mass inertia, which is definitely advantageous in dynamic applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes may also be realized by combining various kinds of teeth. With a right position gearbox a bevel equipment and a planetary gearbox are simply combined. Here as well the overall multiplication factor may be the product of the individual ratios. Depending on the type of gearing and the type of bevel gear stage, the drive and the result can rotate in the same direction.
Advantages of multi-stage gearboxes:
Wide variety of ratios
Continuous 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 degree of efficiency
The automatic 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 has become complex in character and therefore there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-based synthesis of three levels of freedom (DOF) high-rate planetary gearbox offers been offered in this paper, which derives an efficient 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 transmission power stream and relative power efficiency have been decided to analyse the gearbox design. A simulation-based screening and validation have already been performed which show the proposed model is certainly effective and produces satisfactory shift quality through better torque characteristics while shifting the gears. A fresh heuristic method to determine suitable compounding arrangement, predicated on mechanism enumeration, for creating a gearbox layout 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 large reduction in a small volume [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 first literatures [3-5], the vibration structure of some example planetary gears are recognized using lumped-parameter models, but they didn’t provide general conclusions. Lin and Parker [6-7] formally determined and proved the vibration structure of planetary gears with the same/unequal world spacing. They analytically classified all planetary gears settings into exactly three categories, rotational, translational, and planet settings. 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 speed gears with gyroscopic effects [12].
The organic frequencies and vibration modes of multi-stage planetary gears have also received attention. Kahraman [13] set up a family group of torsional dynamics versions for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic style of substance planetary gears of general description including translational degrees of freedom, which allows an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of compound planetary gears had been analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are several researchers focusing on the nonlinear dynamic characteristics of the multi-stage planetary gears for engineering applications, such as TBM [15] and wind mill [16].
Based on the aforementioned versions and vibration framework of planetary gears, many experts worried the sensitivity of the organic frequencies and vibration modes to system parameters. They investigated the result of modal parameters such as 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 consequences 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 variations based on 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 organized vibration modes to show that eigenvalue loci of different mode types at all times cross and those of the same setting type veer as a model parameter is certainly varied.
However, most of the current studies only referenced the technique used for single-stage planetary gears to investigate the modal characteristics of multi-stage planetary gears, while the differences between both of these types of planetary gears were ignored. Because of the multiple examples of freedom in multi-stage planetary gears, more detailed division of organic frequencies must analyze the influence of different program parameters. The objective of this paper is definitely to propose an innovative way of examining the coupled modes in multi-stage planetary gears to investigate 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 produced by tooth mesh forces. In this paper, sensitivity of natural frequencies and vibration settings 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 established can combine the same or different ratios
3. Planetary gear set comes in plastic, sintered metal, and steel, based 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, result shafts
The planetary gear is a special kind of gear drive, where the multiple planet gears revolve around a centrally arranged sun gear. The planet gears are mounted on a planet carrier and engage positively within an internally toothed ring equipment. Torque and power are distributed among several planet gears. Sun equipment, planet carrier and ring equipment may either be driving, driven or set. Planetary gears are used in automotive construction and shipbuilding, as well 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 includes two planet gear pieces, each with three planet 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 transmission ratios. The apparatus is accelerated with a cable drum and a adjustable set of weights. The set of weights is raised via a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel allows free further rotation following the weight has been released. The weight is definitely captured by a shock absorber. A transparent protective cover stops accidental contact with the rotating parts.
To be able to determine the effective torques, the force measurement measures the deflection of bending beams. Inductive quickness sensors on all drive gears allow the speeds to end up being measured. The measured ideals are transmitted right to a PC 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 planet 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 enables free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
power measurement on different gear levels 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
sun gears: 24-tooth, d-pitch circle: 48mm
planet gears: 24-tooth, d-pitch circle: 48mm
ring gears: 72-tooth, d-pitch circle: 144mm
Drive
group 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 levels of freedom. Planet gears rotate around axes that revolve around a sunlight gear, which spins set up. A ring equipment binds the planets externally and is completely fixed. The concentricity of the planet grouping with sunlight and ring gears implies that the torque bears through a straight collection. Many power trains are “comfortable” prearranged straight, and the absence of offset shafts not merely decreases space, it eliminates the necessity to redirect the energy or relocate other components.
In a straightforward planetary setup, input power turns the sun gear at high rate. The planets, spaced around the central axis of rotation, mesh with the sun along with the fixed ring gear, so they are forced to orbit as they roll. All the planets are installed to a single rotating member, known as a cage, arm, or carrier. As the planet carrier turns, it delivers low-speed, high-torque output.
A fixed component isn’t usually essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output powered by two inputs, or an individual input traveling two outputs. For example, the differential that drives the axle within an car is usually 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 theory 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 go deeper with this “planetary” theme. Compound (as opposed to simple) planetary trains have at least two planet gears attached in line to the same shaft, rotating and orbiting at the same swiftness while meshing with different gears. Compounded planets can possess different tooth figures, as can the gears they mesh with. Having such options significantly expands the mechanical options, and allows more reduction per stage. Compound planetary trains can certainly be configured so the world carrier shaft drives at high speed, while the reduction issues from sunlight 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 is not essential.
Planet gears, for his or her size, engage a whole lot of teeth as they circle the sun gear – therefore they can certainly accommodate several turns of the driver for every result shaft revolution. To execute a comparable decrease between a standard pinion and gear, a sizable gear will need to mesh with a rather small pinion.
Simple 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 many times higher. There are obvious ways to further decrease (or as the case could be, increase) acceleration, such as for example connecting planetary multi stage planetary gearbox phases in series. The rotational result of the initial stage is linked to the input of the next, and the multiple of the average person ratios represents the final reduction.
Another option is to introduce regular gear reducers into a planetary train. For example, the high-rate power might go through an ordinary fixedaxis pinion-and-gear set before the planetary reducer. This kind of a configuration, called a hybrid, may also be favored as a simplistic option to additional planetary levels, or to lower input speeds that are too much for some planetary units to handle. It also has an offset between the input and result. If the right angle is needed, bevel or hypoid gears are sometimes attached to an inline planetary program. Worm and planetary combinations are uncommon because the worm reducer by itself delivers such high adjustments in speed.