With single spur gears, a set 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 your drive shaft and the result shaft can be reversed. The overall multiplication element of multi-stage gearboxes can be calculated by multiplying the ratio of each gear stage.
The drive speed is reduced or increased by the factor of the apparatus ratio, depending on whether it’s a ratio to gradual or a ratio to fast. In nearly all applications ratio to slower is required, because the drive torque is multiplied by the entire multiplication factor, unlike the drive speed.
A multi-stage spur gear could be realized in a technically meaningful method up to gear ratio of around 10:1. The reason behind this is based on the ratio of the number of the teeth. From a ratio of 10:1 the generating gearwheel is extremely small. This has a poor 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 merely increasing the space 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 average person ratios of 5:1 and 4:1, for instance. Instead of the drive shaft the planetary carrier contains the sun gear, which drives the following planet stage. A three-stage gearbox is definitely obtained through increasing the distance of the ring gear and adding another planet stage. A tranny ratio of 100:1 is obtained using person ratios of 5:1, 5:1 and 4:1. Basically, all person ratios can be combined, which results in a large number of ratio options for multi-stage planetary gearboxes. The transmittable torque could be increased using extra planetary gears when performing this. The direction of rotation of the drive shaft and the result shaft is always the same, so long as the ring gear or casing is fixed.
As the amount of equipment stages increases, the efficiency of the overall gearbox is decreased. With a ratio of 100:1 the effectiveness is leaner than with a ratio of 20:1. To be able to counteract this situation, the actual fact that the power loss of the drive stage is certainly low should be taken into concern when using multi-stage gearboxes. That is achieved by reducing gearbox seal friction loss or having a drive stage that’s geometrically smaller, for example. 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 the right position gearbox a bevel gear and a planetary gearbox are simply just combined. Here too the entire multiplication factor may be the product of the individual ratios. Depending on the type of gearing and the type of bevel equipment stage, the drive and the output can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide range of ratios
Constant concentricity with planetary gears
Compact style with high transmission ratios
Mix 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 typical feature. With the upsurge in design intricacies of planetary gearbox, mathematical modelling is becoming complex in nature and therefore there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three degrees of freedom (DOF) high-velocity planetary gearbox has been offered in this paper, which derives an efficient gear shifting mechanism through designing the transmitting schematic of eight speed gearboxes compounded with four planetary equipment sets. Furthermore, by making use of lever analogy, the transmitting power flow and relative power efficiency have been decided to analyse the gearbox design. A simulation-based assessment and validation have already been performed which display the proposed model is definitely efficient and produces satisfactory shift quality through better torque features while shifting the gears. A new heuristic method to determine appropriate compounding arrangement, predicated on mechanism enumeration, for designing a gearbox layout 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 benefits of high power density and large reduction in a little volume [1]. The vibration and noise problems of multi-stage planetary gears are always 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 identified 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 equivalent/unequal world spacing. They analytically categorized all planetary gears settings into exactly three categories, rotational, translational, and planet settings. Parker [8] also investigated the clustering phenomenon of the three setting types. In the latest literatures, the systematic classification of modes were carried into systems modeled with an elastic continuum band equipment [9], helical planetary gears [10], herringbone planetary gears [11], and high rate gears with gyroscopic results [12].
The organic frequencies and vibration modes of multi-stage planetary gears also have received attention. Kahraman [13] founded a family group of torsional dynamics versions for substance planetary gears under different kinematic configurations. Kiracofe [14] developed a dynamic style of compound planetary gears of general description including translational examples of freedom, which allows an infinite number of kinematic combinations. They mathematically proved that the modal characteristics of substance planetary gears had been analogous to a straightforward, 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 for example TBM [15] and wind turbine [16].
Based on the aforementioned versions and vibration structure of planetary gears, many experts worried the sensitivity of the organic frequencies and vibration modes to program parameters. They investigated the effect of modal parameters such as tooth mesh stiffness, world bearing stiffness and support stiffness on planetary equipment natural frequencies and vibration settings [17-19]. Parker et al. [20-21] mathematically analyzed the effects of style 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 variants based on the well-defined vibration setting properties, and founded 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 setting types usually cross and those of the same setting type veer as a model parameter is certainly varied.
However, many of the current studies just referenced the method used for single-stage planetary gears to analyze the modal characteristics of multi-stage planetary gears, as 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 must analyze the impact of different program parameters. The objective of this paper is definitely to propose an innovative way of analyzing the coupled settings 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 organic frequencies and vibration modes to both gear 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 arranged can combine the same or different ratios
3. Planetary gear set comes in plastic, sintered steel, and steel, based on different application
4. Hight efficiency: 98% efficiency at single decrease, 95% at double reduction
5. Planetary gear set torque range: Low torque, middle torque, high torque
6. Easy linking with couplings, input shafts, result shafts
The planetary gear is a special kind of gear drive, in which the multiple planet gears revolve around a centrally arranged sun gear. The earth gears are mounted on a world 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 equipment may either be generating, driven or fixed. Planetary gears are used 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 contains two planet gear pieces, each with three planet gears. The ring gear of the 1st stage is certainly coupled to the earth carrier of the second stage. By fixing individual gears, it is possible to configure a total of four different tranny ratios. The apparatus is accelerated via a cable drum and a variable group of weights. The set of weights is elevated via a crank. A ratchet stops the weight from accidentally escaping. A clamping roller freewheel allows free further rotation following the weight offers been released. The weight is certainly captured by a shock absorber. A transparent protective cover stops accidental connection with the rotating parts.
To be able to determine the effective torques, the drive measurement measures the deflection of bending beams. Inductive rate sensors on all drive gears permit the speeds to become measured. The measured values are transmitted directly to a Computer via USB. The data acquisition software is included. The angular multi stage planetary gearbox acceleration could be read from the diagrams. Effective mass moments 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 allows free further rotation following the weight has been released
shock absorber for weight
transparent protective cover
force measurement on different equipment stages 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
sun gears: 24-tooth, d-pitch circle: 48mm
planet gears: 24-tooth, d-pitch circle: 48mm
band 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 phase; 120V, 60Hz, 1 phase
UL/CSA optional
he most basic type of planetary gearing involves three sets of gears with different degrees of freedom. World gears rotate around axes that revolve around a sunlight gear, which spins set up. 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 bears through a straight series. Many power trains are “comfortable” lined up straight, and the lack of offset shafts not only decreases space, it eliminates the necessity to redirect the energy or relocate other parts.
In a simple planetary setup, input power turns the sun gear at high velocity. 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 as they roll. All of the planets are installed to an individual rotating member, called a cage, arm, or carrier. As the planet carrier turns, it delivers low-speed, high-torque output.
A fixed component isn’t generally essential, though. In differential systems every member rotates. Planetary arrangements such as this accommodate a single result powered by two inputs, or a single input driving two outputs. For instance, the differential that drives the axle in an automobile is definitely 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.
Even a simple planetary gear train provides two inputs; an anchored ring gear represents a continuous insight of zero angular velocity.
Designers can proceed deeper with this “planetary” theme. Compound (instead of simple) planetary trains have at least two planet gears attached in range to the same shaft, rotating and orbiting at the same speed while meshing with different gears. Compounded planets can possess different tooth numbers, 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 world carrier shaft drives at high velocity, while the reduction issues from sunlight shaft, if the developer prefers this. One more thing about compound planetary systems: the planets can mesh with (and revolve around) both fixed and rotating exterior gears simultaneously, therefore a ring gear is not essential.
Planet gears, because of their size, engage a whole lot of teeth as they circle the sun equipment – therefore they can simply accommodate several turns of the driver for every result 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.
Simple planetary gears generally provide reductions as high as 10:1. Substance planetary systems, which are more elaborate compared to the simple versions, can offer reductions many times higher. There are obvious ways to additional reduce (or as the case could be, increase) quickness, such as connecting planetary phases in series. The rotational result of the initial stage is linked to the input of another, and the multiple of the individual ratios represents the final reduction.
Another choice is to introduce regular gear reducers into a planetary teach. For instance, the high-acceleration power might pass through an ordinary fixedaxis pinion-and-gear set prior to the planetary reducer. Such a configuration, known as 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 take care of. It also provides an offset between the input and result. If the right angle is necessary, bevel or hypoid gears are sometimes mounted on an inline planetary system. Worm and planetary combinations are rare because the worm reducer alone delivers such high adjustments in speed.