With single spur gears, a pair 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 direction of rotation between your drive shaft and the result shaft is definitely reversed. The overall multiplication aspect of multi-stage gearboxes is certainly calculated by multiplying the ratio of every gear stage.
The drive speed is reduced or increased by the factor of the apparatus ratio, depending on whether it is a ratio to slow or a ratio to fast. In the majority of applications ratio to slower is required, because the drive torque is certainly multiplied by the entire 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 approximately 10:1. The reason for this is based on the ratio of the amount of the teeth. From a ratio of 10:1 the generating gearwheel is extremely small. This has a negative effect on the tooth geometry and the torque that is becoming 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 basically increasing the distance of the ring equipment and with serial arrangement of many individual planet phases. A planetary equipment with a ratio of 20:1 can be manufactured from the individual ratios of 5:1 and 4:1, for instance. Instead of the drive shaft the planetary carrier contains the sun equipment, which drives the following world stage. A three-stage gearbox is usually obtained by way of increasing the length of the ring equipment and adding another world stage. A transmitting ratio of 100:1 is obtained using individual ratios of 5:1, 5:1 and 4:1. Basically, all person ratios can be combined, which outcomes in a large number of ratio options for multi-stage planetary gearboxes. The transmittable torque can 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, provided that the ring equipment or casing 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. In order to counteract this circumstance, the actual fact that the power lack of the drive stage is certainly low should be taken into account when working with multi-stage gearboxes. That is achieved by reducing gearbox seal friction reduction or having a drive stage that’s geometrically smaller, for example. This also decreases the mass inertia, which is certainly advantageous in powerful applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes may also be realized by combining different types of teeth. With a right position gearbox a bevel equipment and a planetary gearbox are simply combined. Here as well the entire multiplication factor is the product of the individual ratios. Depending on the kind of gearing and the kind of bevel equipment 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
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 quite crucial for the high-speed vehicles, where in fact the planetary or epicyclic gearbox is a standard feature. With the increase in design intricacies of planetary gearbox, mathematical modelling has become complex in nature and therefore there is a need for modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three levels of freedom (DOF) high-rate planetary gearbox offers been shown in this paper, which derives an efficient gear shifting system through designing the transmission schematic of eight acceleration gearboxes compounded with four planetary gear sets. Furthermore, by using lever analogy, the transmitting power stream and relative power effectiveness have been decided to analyse the gearbox design. A simulation-based testing and validation have been performed which show the proposed model is certainly effective and produces satisfactory change quality through better torque features while shifting the gears. A new heuristic solution to determine suitable compounding arrangement, based on mechanism enumeration, for designing a gearbox layout is proposed here.
Multi-stage planetary gears are trusted in many applications such as automobiles, helicopters and tunneling uninteresting machine (TBM) due to their advantages of high power density and large reduction in a small volume [1]. The vibration and noise problems of multi-stage planetary gears are constantly the focus of interest 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, however they didn’t give general conclusions. Lin and Parker [6-7] formally determined and proved the vibration framework of planetary gears with equal/unequal world spacing. They analytically classified all planetary gears settings into exactly three types, rotational, translational, and planet modes. 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 swiftness gears with gyroscopic results [12].
The organic frequencies and vibration settings 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 explanation including translational levels of freedom, which allows thousands of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears had been analogous to a simple, single-stage planetary gear system. Meanwhile, there are several researchers focusing 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 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 result of modal parameters such as tooth mesh stiffness, world 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 natural frequencies and vibration settings 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 founded the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary equipment eigenvalues. They utilized the organized vibration modes to show that eigenvalue loci of different mode types usually cross and those of the same setting type veer as a model parameter is usually varied.
However, the majority of of the current studies just referenced the technique used for single-stage planetary gears to analyze the modal features of multi-stage planetary gears, while the differences between both of these types of planetary gears had been ignored. Because of the multiple examples of freedom in multi-stage planetary gears, more descriptive division of natural frequencies must analyze the impact of different system parameters. The objective of this paper is certainly to propose an innovative way of examining the coupled settings 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 organic 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, 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 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 sunlight gear. The earth gears are mounted on a world carrier and engage positively within an internally toothed band equipment. Torque and power are distributed among a number of planet gears. Sun equipment, planet carrier and ring gear may either be generating, 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 includes two planet gear sets, each with three world gears. The ring equipment of the initial stage is coupled to the earth carrier of the second stage. By fixing person gears, it is possible to configure a total of four different transmission ratios. The gear is accelerated with a cable drum and a adjustable set of weights. The set of weights is raised with a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller multi stage planetary gearbox freewheel enables free further rotation after the weight provides been released. The weight is caught by a shock absorber. A transparent protective cover helps prevent accidental contact with the rotating parts.
In order to determine the effective torques, the drive measurement measures the deflection of bending beams. Inductive quickness sensors on all drive gears permit the speeds to end up being measured. The measured ideals are transmitted right to a Computer via USB. The data acquisition software is roofed. The angular acceleration could 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 world gears per stage
four different transmission ratios possible
gear 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 following the weight has been released
shock absorber for weight
transparent protective cover
power measurement on different gear levels 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
world 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 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 examples of freedom. Planet 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 sunlight and ring gears implies that the torque carries through a straight line. Many power trains are “comfortable” lined up straight, and the absence of offset shafts not only decreases space, it eliminates the need to redirect the energy or relocate other elements.
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 as well as the fixed ring equipment, so they are forced to orbit because they roll. All the planets are mounted to an individual rotating member, known as a cage, arm, or carrier. As the earth 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 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 vehicle is planetary bevel gearing – the wheel speeds represent two outputs, which must differ to handle corners. Bevel gear planetary systems operate along the same principle as parallel-shaft systems.
A good simple planetary gear train has two inputs; an anchored band gear represents a constant input 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 range to the same shaft, rotating and orbiting at the same velocity while meshing with different gears. Compounded planets can have different tooth quantities, as can the gears they mesh with. Having this kind of options greatly expands the mechanical opportunities, and allows more decrease per stage. Compound planetary trains can certainly be configured so the world carrier shaft drives at high quickness, while the reduction issues from the sun 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 isn’t essential.
Planet gears, because of their size, engage a whole lot of teeth because they circle the sun gear – therefore they can easily accommodate many turns of the driver for every result shaft revolution. To perform a comparable reduction between a typical pinion and equipment, a sizable gear will need to mesh with a fairly small pinion.
Simple planetary gears generally provide reductions as high as 10:1. Substance planetary systems, which are far more elaborate than the simple versions, can provide reductions many times higher. There are apparent ways to further reduce (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 average person ratios represents the final reduction.
Another choice is to introduce regular gear reducers into a planetary train. For example, the high-velocity power might pass through a typical fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, known as a hybrid, is sometimes preferred as a simplistic option to additional planetary levels, or to lower insight 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 necessary, bevel or hypoid gears are sometimes mounted on an inline planetary program. Worm and planetary combinations are rare since the worm reducer by itself delivers such high adjustments in speed.