With single spur gears, a couple of gears forms a gear stage. In the event that you connect several equipment 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 output shaft can be reversed. The entire multiplication aspect 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 sluggish or a ratio to fast. In the majority of applications ratio to slow is required, since the drive torque can be multiplied by the overall multiplication factor, unlike the drive rate.
A multi-stage spur gear can be realized in a technically meaningful way up to a gear ratio of around 10:1. The reason for this is based on the ratio of the amount of tooth. From a ratio of 10:1 the driving gearwheel is extremely little. This has a negative effect on the tooth geometry and the torque that is becoming 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 simply increasing the length of the ring equipment and with serial arrangement of many individual planet levels. A planetary equipment with a ratio of 20:1 could be manufactured from the individual ratios of 5:1 and 4:1, for instance. 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 way of increasing the distance of the ring equipment and adding another world stage. A transmitting ratio of 100:1 is obtained using person ratios of 5:1, 5:1 and 4:1. Basically, all individual ratios can be combined, which results in a sizable number of ratio choices for multi-stage planetary gearboxes. The transmittable torque can be increased using additional planetary gears when doing this. The path of rotation of the drive shaft and the result shaft is often the same, so long as the ring gear or housing is fixed.
As the number 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 situation, the fact that the power lack of the drive stage is definitely low must be taken into thought when working with multi-stage gearboxes. That is achieved by reducing gearbox seal friction reduction or having a drive stage that is geometrically smaller, for example. This also decreases the mass inertia, which can be 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 the right position gearbox a bevel equipment 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 type of gearing and the kind of bevel gear stage, the drive and the result can rotate in the same direction.
Advantages 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 (in comparison to single-stage gearboxes):
More complex design
Lower degree of efficiency
The automated transmission system is very crucial for the high-speed vehicles, where the planetary or epicyclic gearbox is a standard feature. With the increase in design intricacies of planetary gearbox, mathematical modelling is becoming complex in nature and therefore there is a need for modelling of multistage planetary gearbox like the shifting scheme. A random search-based synthesis of three levels of freedom (DOF) high-velocity planetary gearbox offers been presented in this paper, which derives an efficient gear shifting mechanism through designing the transmission schematic of eight swiftness gearboxes compounded with four planetary equipment sets. Furthermore, by making use of lever analogy, the transmitting power stream and relative power effectiveness have been identified to analyse the gearbox style. A simulation-based screening and validation have been performed which show the proposed model can be effective and produces satisfactory change quality through better torque features while shifting the gears. A new heuristic solution to determine appropriate 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 for example automobiles, helicopters and tunneling uninteresting 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 at all times 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 determined using lumped-parameter models, however they didn’t provide general conclusions. Lin and Parker [6-7] formally determined and proved the vibration structure of planetary gears with equivalent/unequal world spacing. They analytically categorized all planetary gears modes into exactly three categories, rotational, translational, and world settings. Parker [8] also investigated the clustering phenomenon of the three mode types. In the recent literatures, the systematic classification of modes were carried into systems modeled with an elastic continuum band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high rate gears with gyroscopic effects [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 compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic model 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 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 experts 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 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 based on the well-defined vibration mode properties, and founded 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 constantly cross and those of the same setting type veer as a model parameter is usually varied.
However, the majority of 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 had been ignored. Because of the multiple degrees of freedom in multi-stage planetary gears, more descriptive division of organic frequencies are required to analyze the influence of different program parameters. The aim of this paper can be 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 gear vibration while keeping the main dynamic behavior produced 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 are available in wide reduction gear ratios
2. Gear set 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 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 type of gear drive, in which the multiple planet gears revolve around a centrally arranged sunlight gear. The planet gears are mounted on a planet carrier and engage positively in an internally toothed band equipment. Torque and power are distributed among many planet gears. Sun equipment, planet carrier and band gear may either be generating, 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 includes two planet gear pieces, each with three world gears. The ring equipment of the initial stage is certainly coupled to the planet carrier of the second stage. By fixing individual gears, you’ll be able to configure a complete of four different transmission ratios. The gear is accelerated via a cable drum and a adjustable group of weights. The group of weights is elevated via a crank. A ratchet prevents the weight from multi stage planetary gearbox accidentally escaping. A clamping roller freewheel enables free further rotation following the weight offers been released. The weight is definitely captured 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 quickness sensors on all drive gears allow the speeds to be measured. The measured values are transmitted right to a Personal computer via USB. The data acquisition software is roofed. The angular acceleration can be read from the diagrams. Effective mass moments of inertia are dependant on the angular acceleration.
investigation of the powerful 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 allows free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
power measurement on different equipment phases 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
world 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 type of planetary gearing involves three sets of gears with different levels of freedom. World gears rotate around axes that revolve around a sunlight gear, which spins in place. A ring equipment binds the planets externally and is completely fixed. The concentricity of the earth grouping with the sun and ring gears means that the torque carries through a straight collection. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not only decreases space, it eliminates the need to redirect the energy or relocate other parts.
In a straightforward planetary setup, input power turns the sun gear at high acceleration. 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 because they roll. All of 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 set component isn’t usually essential, though. In differential systems every member rotates. Planetary arrangements like this accommodate a single output powered by two inputs, or an individual input generating two outputs. For instance, the differential that drives the axle in an car is usually 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 provides two inputs; an anchored band 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 world gears attached in collection to the same shaft, rotating and orbiting at the same rate while meshing with different gears. Compounded planets can have got different tooth amounts, 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 therefore the planet carrier shaft drives at high speed, while the reduction problems from sunlight shaft, if the designer prefers this. Another thing about compound 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 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 output shaft revolution. To perform 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 often higher. There are apparent ways to further reduce (or as the case may be, increase) speed, such as for example 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 individual ratios represents the final reduction.
Another option is to introduce standard gear reducers into a planetary teach. For instance, the high-swiftness 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 preferred 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 provides an offset between the input and result. If a 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.