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 every gear stage, the path of rotation between the drive shaft and the result shaft is certainly reversed. The entire multiplication factor of multi-stage gearboxes is 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 sluggish or a ratio to fast. In the majority of applications ratio to slower is required, because 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 a 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 negative 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 may be accomplished by merely increasing the space of the ring gear and with serial arrangement of many individual planet stages. 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 provides the sun gear, which drives the following planet stage. A three-stage gearbox is definitely obtained by means of increasing the length of the ring gear and adding another world 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 huge number of ratio choices for multi-stage planetary gearboxes. The transmittable torque can be increased using extra planetary gears when doing this. The path of rotation of the drive shaft and the result shaft is constantly the same, provided that the ring gear or housing is fixed.
As the number of gear stages increases, the efficiency of the entire gearbox is reduced. With a ratio of 100:1 the effectiveness is leaner than with a ratio of 20:1. To be able to counteract this circumstance, the actual fact that the power loss of the drive stage can be low should be taken into factor 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 certainly 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 position gearbox a bevel gear and a planetary gearbox are simply combined. Here too the entire multiplication factor is the product of the individual ratios. Depending on the type of gearing and the type of bevel gear stage, the drive and the output can rotate in the same path.
Advantages of multi-stage gearboxes:
Wide variety of ratios
Constant concentricity with planetary gears
Compact design 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 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 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-velocity planetary gearbox provides been offered in this paper, which derives an efficient gear shifting mechanism through designing the transmitting schematic of eight acceleration gearboxes compounded with four planetary gear sets. Furthermore, with the aid of lever analogy, the transmitting power stream and relative power performance have been motivated to analyse the gearbox design. A simulation-based tests and validation have been performed which display the proposed model is certainly efficient and produces satisfactory shift quality through better torque features while shifting the gears. A fresh heuristic solution to determine ideal compounding arrangement, based on mechanism enumeration, for designing a gearbox design is proposed here.
Multi-stage planetary gears are trusted in many applications such as for example automobiles, helicopters and tunneling uninteresting machine (TBM) because of their benefits of high power density and large reduction in a small quantity [1]. The vibration and noise problems of multi-stage planetary gears are constantly 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 framework of some example planetary gears are discovered using lumped-parameter models, however they didn’t give general conclusions. Lin and Parker [6-7] formally recognized and proved the vibration structure of planetary gears with equivalent/unequal world spacing. They analytically categorized all planetary gears modes 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 settings 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 effects [12].
The organic frequencies and vibration modes of multi-stage planetary gears also have received attention. Kahraman [13] established a family group of torsional dynamics multi stage planetary gearbox models for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic style of substance planetary gears of general description including translational levels of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal characteristics of compound planetary gears were analogous to a simple, single-stage planetary gear program. Meanwhile, there are plenty of 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 models and vibration structure of planetary gears, many experts worried the sensitivity of the natural frequencies and vibration modes to system parameters. They investigated the result of modal parameters such as for example tooth mesh stiffness, world bearing stiffness and support stiffness on planetary equipment organic frequencies and vibration settings [17-19]. Parker et al. [20-21] mathematically analyzed the consequences of style parameters on natural frequencies and vibration settings both for the single-stage and substance planetary gears. They proposed closed-type expressions for the eigensensitivities to model parameter variants based on the well-defined vibration setting properties, and established the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They used the structured vibration modes showing that eigenvalue loci of different setting types always cross and the ones of the same setting type veer as a model parameter is varied.
However, most of the existing studies just 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 degrees of freedom in multi-stage planetary gears, more descriptive division of organic frequencies are required to analyze the impact of different program parameters. The aim of this paper is 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 used to simplify the analytical investigation of equipment vibration while keeping the primary dynamic behavior produced 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 are available in wide reduction gear ratios
2. Gear established can combine the same or different ratios
3. Planetary gear set is available 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, result shafts
The planetary gear is a special type of gear drive, in which the multiple planet gears revolve around a centrally arranged sun gear. The earth gears are installed on a world carrier and engage positively in an internally toothed ring equipment. Torque and power are distributed among several planet gears. Sun gear, planet carrier and ring gear may either be traveling, driven or fixed. Planetary gears are found 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 consists of two planet gear sets, each with three planet gears. The ring equipment of the first stage is coupled to the earth carrier of the next stage. By fixing individual gears, you’ll be able to configure a complete of four different transmission ratios. The apparatus is accelerated via a cable drum and a adjustable group of weights. The set of weights is raised via a crank. A ratchet prevents the weight from accidentally escaping. A clamping roller freewheel enables free further rotation after the weight provides been released. The weight is captured by a shock absorber. A transparent protective cover stops accidental connection with the rotating parts.
In order to determine the effective torques, the drive measurement measures the deflection of bending beams. Inductive velocity sensors on all drive gears permit the speeds to end up being measured. The measured ideals 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 powerful 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 following the weight has been released
shock absorber for weight
transparent protective cover
pressure measurement on different gear stages 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
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
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 form 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 in place. A ring equipment binds the planets on the outside and is completely fixed. 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” 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 the sun gear at high swiftness. The planets, spaced around the central axis of rotation, mesh with the sun along with the fixed ring gear, so they are pressured to orbit because they roll. All the planets are installed to an individual rotating member, known as a cage, arm, or carrier. As the earth carrier turns, it provides low-speed, high-torque output.
A fixed component isn’t often essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single result powered by two inputs, or a single input driving two outputs. For instance, the differential that drives the axle within an car 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.
A good simple planetary gear train provides two inputs; an anchored band gear represents a continuous insight 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 swiftness 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 greatly expands the mechanical options, and allows more reduction per stage. Substance planetary trains can simply be configured therefore the planet carrier shaft drives at high acceleration, 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 fixed and rotating external gears simultaneously, therefore a ring gear isn’t essential.
Planet gears, for their size, engage a whole lot of teeth as they circle the sun equipment – therefore they can easily accommodate several turns of the driver for each result shaft revolution. To execute a comparable decrease between a standard pinion and equipment, a sizable gear will need to mesh with a fairly small pinion.
Simple planetary gears generally offer reductions as high as 10:1. Compound planetary systems, which are far 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) velocity, such as connecting planetary levels in series. The rotational result of the 1st stage is linked to the input of the next, and the multiple of the average person ratios represents the ultimate reduction.
Another choice is to introduce regular gear reducers right into a planetary teach. For example, the high-quickness power might pass through a typical fixedaxis pinion-and-gear set prior to the planetary reducer. This kind of a configuration, known as a hybrid, may also be favored as a simplistic alternative to additional planetary levels, or to lower input speeds that are too high for a few planetary units to take care of. It also provides an offset between your input and result. If a right angle is needed, bevel or hypoid gears are occasionally mounted on an inline planetary program. Worm and planetary combinations are uncommon because the worm reducer by itself delivers such high adjustments in speed.