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 referred to as a multi-stage gearbox. For each gear stage, the direction of rotation between the drive shaft and the output shaft can be reversed. The entire multiplication factor of multi-stage gearboxes is definitely 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 slow or a ratio to fast. In nearly all applications ratio to slow is required, since the drive torque is multiplied by the overall multiplication aspect, unlike the drive velocity.
A multi-stage spur gear can be realized in a technically meaningful method up to a gear ratio of around 10:1. The reason behind this is based on the ratio of the amount of teeth. From a ratio of 10:1 the driving gearwheel is extremely little. This has a poor influence on the tooth geometry and the torque that is 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 just increasing the space of the ring equipment and with serial arrangement of many individual planet levels. A planetary gear with a ratio of 20:1 can be manufactured from the individual ratios of 5:1 and 4:1, for example. Instead of the drive shaft the planetary carrier contains the sun equipment, which drives the following world stage. A three-stage gearbox is obtained through increasing the length of the ring gear 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 individual 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 doing this. The direction of rotation of the drive shaft and the result shaft is constantly the same, provided that the ring gear or casing is fixed.
As the number of equipment stages increases, the efficiency of the overall gearbox is reduced. With a ratio of 100:1 the performance is lower 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 thought when using multi-stage gearboxes. That 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 advantageous in dynamic applications. Single-stage planetary gearboxes will be the most efficient.
Multi-stage gearboxes may 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 entire 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 result can rotate in the same path.
Benefits of multi-stage gearboxes:
Wide range of ratios
Continuous 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 (compared to single-stage gearboxes):
More complex design
Lower amount of efficiency
The automated transmission system is quite crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a typical feature. With the increase in design intricacies of planetary gearbox, mathematical modelling is becoming complex in nature and for that reason there is a dependence on modelling of multistage planetary gearbox including the shifting scheme. A random search-centered synthesis of three levels of freedom (DOF) high-speed planetary gearbox offers been shown in this paper, which derives an efficient gear shifting mechanism through designing the transmitting schematic of eight speed gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the transmission power movement and relative power effectiveness have been identified to analyse the gearbox style. A simulation-based tests and validation have already been performed which display the proposed model is certainly effective and produces satisfactory shift quality through better torque features while shifting the gears. A new heuristic solution to determine ideal 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 for example automobiles, helicopters and tunneling boring machine (TBM) because of their advantages of high power density and large reduction in a small quantity [1]. The vibration and noise problems of multi-stage planetary gears are usually 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 framework of some example planetary gears are discovered using lumped-parameter models, however they didn’t provide general conclusions. Lin and Parker [6-7] formally discovered and proved the vibration structure of planetary gears with the same/unequal world spacing. They analytically classified all planetary gears settings into exactly three classes, 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 modes had been carried into systems modeled with an elastic continuum ring gear [9], helical planetary gears [10], herringbone planetary gears [11], and high swiftness gears with gyroscopic results [12].
The natural frequencies and vibration settings of multi-stage planetary gears also have received attention. Kahraman [13] established a family of torsional dynamics versions for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model of compound planetary gears of general explanation including translational degrees of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears were analogous to a straightforward, single-stage planetary gear system. 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 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 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 natural frequencies and vibration modes both for the single-stage and substance planetary gears. They proposed closed-form 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 gear eigenvalues. They utilized the organized vibration modes to show that eigenvalue loci of different mode types at all times cross and the ones of the same mode type veer as a model parameter is certainly varied.
However, most of the existing studies only referenced the technique used for single-stage planetary gears to analyze 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 levels of freedom in multi-stage planetary gears, more detailed division of natural frequencies are required to analyze the influence of different program parameters. The aim of this paper is usually to propose a novel method of examining the coupled modes in multi-stage planetary gears to investigate 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 settings to both gear 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 metallic, and steel, based on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear established torque range: Low torque, middle torque, high torque
6. Easy connecting with couplings, input shafts, output shafts
The planetary equipment is a special kind of gear drive, where the multiple planet gears revolve around a centrally arranged sunlight gear. The planet gears are installed on a planet carrier and engage positively in an internally toothed band equipment. Torque and power are distributed among many planet gears. Sun gear, planet carrier and ring gear may either be driving, driven or fixed. Planetary gears are used in automotive structure 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 contains two planet gear sets, each with three planet gears. The ring gear of the first stage can be coupled to the planet carrier of the next stage. By fixing individual gears, it is possible to configure a total of four different tranny ratios. The gear is accelerated via a cable drum and a variable group of weights. The set of weights is raised via a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight has been released. The weight is usually captured by a shock absorber. A transparent protective cover prevents accidental contact with the rotating parts.
To be able to determine the effective torques, the push measurement measures the deflection of bending beams. Inductive rate sensors on all drive gears allow the speeds to be measured. The measured ideals are transmitted directly to a 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 dynamic behaviour of a 2-stage planetary gear
three planet gears per stage
four different transmission ratios possible
equipment is accelerated via cable drum and adjustable 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 phases via 3 bending pubs, 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
group of weights: 5…50kg
max. potential energy: 245,3Nm
Load at standstill
weight forces: 5…70N
Measuring multi stage planetary gearbox 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. Planet gears rotate around axes that revolve around a sun gear, which spins set up. A ring gear binds the planets on the outside and is completely set. The concentricity of the earth grouping with sunlight and ring gears means that the torque bears through a straight collection. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not only reduces space, it eliminates the necessity to redirect the power or relocate other parts.
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 sunlight along with the fixed ring gear, so they are pressured 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 set component isn’t constantly 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 in an vehicle is certainly 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 provides two inputs; an anchored ring gear represents a continuous input of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (as opposed to basic) planetary trains have 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 have got different tooth quantities, as can the gears they mesh with. Having this kind of 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 problems from sunlight shaft, if the developer prefers this. One more thing about compound planetary systems: the planets can mesh with (and revolve around) both set and rotating external gears simultaneously, hence a ring gear isn’t essential.
Planet gears, because of their size, engage a lot of teeth because they circle the sun equipment – therefore they can easily accommodate numerous turns of the driver for every result shaft revolution. To perform a comparable reduction between a typical pinion and gear, a sizable gear will need to mesh with a fairly small pinion.
Simple planetary gears generally provide reductions as high as 10:1. Compound planetary systems, which are more elaborate than the simple versions, can offer reductions often higher. There are apparent ways to further decrease (or as the case may be, increase) quickness, such as connecting planetary stages in series. The rotational output of the 1st 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 right into a planetary train. For instance, the high-speed power might pass through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, called a hybrid, may also be favored as a simplistic option to additional planetary stages, or to lower insight speeds that are too much for some planetary units to handle. It also has an offset between your input and output. If the right angle is needed, bevel or hypoid gears are occasionally attached to an inline planetary program. Worm and planetary combinations are rare because the worm reducer by itself delivers such high adjustments in speed.