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 referred to as a multi-stage gearbox. For every gear stage, the path of rotation between your drive shaft and the output shaft is definitely reversed. The overall multiplication factor of multi-stage gearboxes is 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, because the drive torque is multiplied by the overall multiplication element, unlike the drive swiftness.
A multi-stage spur gear could be realized in a technically meaningful way up to a gear ratio of approximately 10:1. The reason behind this is based on the ratio of the amount of the teeth. From a ratio of 10:1 the driving gearwheel is extremely small. This has a negative influence on the tooth geometry and the torque that’s becoming transmitted. With planetary gears a multi-stage multi stage planetary gearbox gearbox is incredibly easy to realize.
A two-stage gearbox or a three-stage gearbox may be accomplished by just increasing the length of the ring gear and with serial arrangement of many individual planet phases. A planetary gear with a ratio of 20:1 can be manufactured from the average person 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 world stage. A three-stage gearbox can be 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 person ratios could be combined, which results in a large number of ratio choices for multi-stage planetary gearboxes. The transmittable torque can be increased using additional planetary gears when performing this. The direction of rotation of the drive shaft and the result shaft is usually the same, provided that the ring equipment or casing is fixed.
As the amount of gear stages increases, the efficiency of the entire gearbox is decreased. With a ratio of 100:1 the efficiency is leaner than with a ratio of 20:1. In order to counteract this situation, the fact that the power loss of the drive stage is definitely low should be taken into consideration when using multi-stage gearboxes. This is attained by reducing gearbox seal friction loss or having a drive stage that’s geometrically smaller, for example. This also decreases the mass inertia, which is advantageous in dynamic applications. Single-stage planetary gearboxes are the most efficient.
Multi-stage gearboxes can also be realized by combining various kinds of teeth. With the right position gearbox a bevel equipment and a planetary gearbox are simply just combined. Here as well the entire multiplication factor may be 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
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 (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 the planetary or epicyclic gearbox is a standard feature. With the upsurge in style intricacies of planetary gearbox, mathematical modelling is becoming complex in nature and for that reason there is a need for modelling of multistage planetary gearbox including the shifting scheme. A random search-centered synthesis of three examples of freedom (DOF) high-quickness planetary gearbox offers been shown in this paper, which derives an efficient gear shifting system through designing the transmitting schematic of eight swiftness gearboxes compounded with four planetary gear sets. Furthermore, with the help of lever analogy, the tranny power stream and relative power effectiveness have been decided to analyse the gearbox design. A simulation-based tests and validation have already been performed which show the proposed model is definitely efficient and produces satisfactory shift quality through better torque features while shifting the gears. A fresh heuristic method to determine appropriate compounding arrangement, predicated on mechanism enumeration, for developing a gearbox layout is proposed here.
Multi-stage planetary gears are trusted in many applications such as automobiles, helicopters and tunneling boring machine (TBM) due to their advantages of high power density and large reduction in a small quantity [1]. The vibration and noise complications of multi-stage planetary gears are at all times 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 first literatures [3-5], the vibration framework of some example planetary gears are identified using lumped-parameter models, but they didn’t give general conclusions. Lin and Parker [6-7] formally identified and proved the vibration framework of planetary gears with equivalent/unequal world spacing. They analytically classified all planetary gears modes into exactly three categories, 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 ring equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high swiftness gears with gyroscopic effects [12].
The natural frequencies and vibration settings of multi-stage planetary gears have also received attention. Kahraman [13] founded a family of torsional dynamics versions for compound planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic style of compound planetary gears of general description including translational degrees of freedom, which allows an infinite number of kinematic combinations. They mathematically proved that the modal features of compound planetary gears were analogous to a straightforward, single-stage planetary gear program. Meanwhile, there are various 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 program parameters. They investigated the result of modal parameters such as for example tooth mesh stiffness, planet bearing stiffness and support stiffness on planetary gear natural 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 according to the well-defined vibration mode properties, and established the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They utilized the structured vibration modes showing that eigenvalue loci of different setting types constantly cross and those of the same setting type veer as a model parameter is usually varied.
However, most of the current studies just referenced the method 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 examples of freedom in multi-stage planetary gears, more descriptive division of organic frequencies must analyze the influence of different program parameters. The objective 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 amount of freedom models are accustomed to simplify the analytical investigation of equipment vibration while keeping the primary dynamic behavior generated 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 can be found in wide reduction gear ratios
2. Gear set can combine the same or different ratios
3. Planetary gear set is available 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 arranged torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, output shafts
The planetary gear is a special type of gear drive, where the multiple world gears revolve around a centrally arranged sunlight gear. The earth gears are installed on a planet carrier and engage positively in an internally toothed ring equipment. Torque and power are distributed among a number of planet gears. Sun gear, planet carrier and ring equipment may either be traveling, driven or fixed. Planetary gears are found in automotive building 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 powerful 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 earth carrier of the next stage. By fixing individual gears, it is possible to configure a complete of four different transmission ratios. The gear is accelerated with a cable drum and a variable group of weights. The set of weights is raised with a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel allows free further rotation after the weight provides been released. The weight can be caught 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 force measurement measures the deflection of bending beams. Inductive rate sensors on all drive gears allow the speeds to end up being measured. The measured values are transmitted directly to a Personal computer via USB. The info acquisition software is included. The angular acceleration could be read from the diagrams. Effective mass moments of inertia are dependant on 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 variable set of weights
weight raised yourself 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
drive measurement on different equipment levels via 3 bending pubs, 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
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 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 degrees of freedom. World gears rotate around axes that revolve around a sun 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 means that the torque carries through a straight range. Many power trains are “comfortable” prearranged straight, and the lack of offset shafts not only reduces space, it eliminates the need to redirect the power or relocate other elements.
In a straightforward planetary setup, input power turns sunlight gear at high acceleration. The planets, spaced around the central axis of rotation, mesh with sunlight as well as the fixed ring equipment, so they are pressured to orbit because they roll. All the planets are mounted to an individual 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 constantly essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single output driven by two inputs, or a single input traveling two outputs. For instance, the differential that drives the axle within an automobile is usually planetary bevel gearing – the wheel speeds represent two outputs, which must differ to take care of corners. Bevel gear planetary systems operate along the same theory as parallel-shaft systems.
A good simple planetary gear train offers two inputs; an anchored ring gear represents a constant input of zero angular velocity.
Designers can go deeper with this “planetary” theme. Compound (as opposed to basic) planetary trains possess at least two world gears attached in range to the same shaft, rotating and orbiting at the same swiftness while meshing with different gears. Compounded planets can have got different tooth numbers, as can the gears they mesh with. Having such options greatly expands the mechanical possibilities, and allows more decrease per stage. Substance planetary trains can certainly be configured so the planet carrier shaft drives at high speed, 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 external gears simultaneously, therefore a ring gear isn’t essential.
Planet gears, for their size, engage a lot of teeth because they circle the sun gear – therefore they can simply accommodate numerous turns of the driver for every output shaft revolution. To execute a comparable reduction between a standard pinion and gear, a sizable gear will need to mesh with a rather small pinion.
Basic planetary gears generally offer reductions as high as 10:1. Compound 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) speed, such as connecting planetary phases in series. The rotational result of the first stage is linked to the input of another, and the multiple of the average person ratios represents the ultimate reduction.
Another option is to introduce standard gear reducers 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, is sometimes preferred as a simplistic alternative to additional planetary stages, or to lower insight speeds that are too high for a few planetary units to take care of. It also provides an offset between the input and result. If a right angle is needed, bevel or hypoid gears are sometimes mounted on an inline planetary system. Worm and planetary combinations are rare because the worm reducer by itself delivers such high adjustments in speed.