With single spur gears, a couple of gears forms a gear stage. In the event that you connect several equipment pairs one after another, that is referred to as a multi-stage gearbox. For every gear stage, the direction of rotation between your drive shaft and the result shaft is certainly reversed. The overall multiplication factor of multi-stage gearboxes is definitely 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 is a ratio to slow or a ratio to fast. In the majority of applications ratio to gradual is required, since the drive torque is definitely multiplied by the overall multiplication element, unlike the drive quickness.
A multi-stage spur gear could be realized in a technically meaningful way up to a gear ratio of around 10:1. The reason for this lies in the ratio of the amount of tooth. From a ratio of 10:1 the driving gearwheel is extremely small. This has a negative effect on the tooth geometry and the torque that is getting transmitted. With multi stage planetary gearbox 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 several individual planet stages. 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. Rather than the drive shaft the planetary carrier contains the sun gear, which drives the following world stage. A three-stage gearbox is obtained by means of increasing the space of the ring gear and adding another planet stage. A transmission 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 huge number of ratio options for multi-stage planetary gearboxes. The transmittable torque could be increased using additional planetary gears when carrying out this. The direction of rotation of the drive shaft and the result shaft is always the same, provided that the ring gear or housing is fixed.
As the number of equipment stages increases, the efficiency of the overall 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 situation, the fact that the power lack of the drive stage is definitely low should be taken into consideration when using multi-stage gearboxes. That is attained by reducing gearbox seal friction loss or having a drive stage that is geometrically smaller, for instance. This also decreases the mass inertia, which can be advantageous in dynamic 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 angle gearbox a bevel gear and a planetary gearbox are simply combined. Here as well the overall 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 result can rotate in the same direction.
Benefits of multi-stage gearboxes:
Wide variety of ratios
Continuous concentricity with planetary gears
Compact design with high transmission ratios
Mix of different gearbox types possible
Wide range of uses
Disadvantages of multi-stage gearboxes (compared 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 style intricacies of planetary gearbox, mathematical modelling is becoming complex in nature and for that reason there is a dependence on modelling of multistage planetary gearbox like the shifting scheme. A random search-centered synthesis of three examples of freedom (DOF) high-acceleration planetary gearbox offers been offered in this paper, which derives an efficient gear shifting system through designing the tranny schematic of eight quickness gearboxes compounded with four planetary equipment sets. Furthermore, by making use of lever analogy, the transmitting power stream and relative power efficiency have been decided to analyse the gearbox design. A simulation-based examining and validation have already been performed which show the proposed model is definitely efficient and produces satisfactory change quality through better torque features while shifting the gears. A fresh heuristic solution to determine suitable 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 advantages of high power density and large reduction in a small quantity [1]. The vibration and noise problems of multi-stage planetary gears are usually 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 recognized using lumped-parameter models, however they didn’t provide general conclusions. Lin and Parker [6-7] formally identified and proved the vibration framework of planetary gears with equivalent/unequal planet spacing. They analytically categorized all planetary gears settings 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 modes were carried into systems modeled with an elastic continuum band gear [9], helical planetary gears [10], herringbone planetary gears [11], and high velocity gears with gyroscopic results [12].
The natural frequencies and vibration settings of multi-stage planetary gears have also 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 model of substance planetary gears of general explanation including translational degrees of freedom, which enables an infinite number 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 many 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].
According to the aforementioned models and vibration framework of planetary gears, many researchers concerned 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, 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 design parameters on organic 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 mode properties, and founded the relation of eigensensitivities and modal energies. Lin and Parker [22] investigated the veering of planetary gear eigenvalues. They used the organized vibration modes showing that eigenvalue loci of different mode types generally cross and the ones of the same mode type veer as a model parameter is usually varied.
However, many of the existing studies just referenced the method 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 had been ignored. Due to the multiple examples of freedom in multi-stage planetary gears, more descriptive division of natural frequencies must analyze the impact of different program parameters. The objective of this paper is to propose an innovative way of examining 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 main 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 steel, 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 connecting with couplings, input shafts, output 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 gear. Torque and power are distributed among several planet gears. Sun gear, planet carrier and ring equipment may either be generating, driven or set. Planetary gears are used in automotive construction 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 consists of two planet gear units, each with three planet gears. The ring gear of the first stage can be coupled to the earth carrier of the second stage. By fixing individual gears, you’ll be able to configure a total of four different tranny ratios. The gear is accelerated with a cable drum and a variable group of weights. The set of weights is raised via a crank. A ratchet helps prevent the weight from accidentally escaping. A clamping roller freewheel enables free further rotation following the weight has been released. The weight is definitely captured by a shock absorber. A transparent protective cover helps prevent accidental connection with the rotating parts.
To be able to determine the effective torques, the pressure measurement measures the deflection of bending beams. Inductive acceleration sensors on all drive gears permit 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 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 planet 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 after the weight has been released
shock absorber for weight
transparent protective cover
force measurement on different gear phases via 3 bending bars, 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
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 kind of planetary gearing involves three sets of gears with different levels of freedom. Planet gears rotate around axes that revolve around a sun gear, which spins set up. A ring gear binds the planets on the outside and is completely fixed. The concentricity of the earth grouping with the sun and ring gears means that the torque carries through a straight line. Many power trains are “comfortable” prearranged straight, and the lack of offset shafts not only reduces space, it eliminates the necessity to redirect the energy or relocate other elements.
In a simple planetary setup, input power turns sunlight gear at high rate. The planets, spaced around the central axis of rotation, mesh with the sun as well as the fixed ring equipment, 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 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 output driven by two inputs, or a single input generating two outputs. For instance, the differential that drives the axle within 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 basic principle as parallel-shaft systems.
A good simple planetary gear train offers two inputs; an anchored band gear represents a continuous input 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 range to the same shaft, rotating and orbiting at the same acceleration while meshing with different gears. Compounded planets can possess different tooth figures, as can the gears they mesh with. Having this kind of options significantly expands the mechanical possibilities, and allows more decrease per stage. Substance planetary trains can simply be configured therefore the world carrier shaft drives at high acceleration, while the reduction problems 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, hence a ring gear is not essential.
Planet gears, for his or her size, engage a lot of teeth because they circle the sun gear – therefore they can simply accommodate many turns of the driver for every result shaft revolution. To perform a comparable decrease between a typical pinion and gear, a sizable gear will have to mesh with a rather 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 provide reductions many times higher. There are obvious ways to additional reduce (or as the case may be, increase) velocity, such as for example connecting planetary stages in series. The rotational output of the first stage is linked to the input of another, 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-velocity power might go 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 preferred as a simplistic option to additional planetary phases, or to lower input speeds that are too much for a few planetary units to handle. It also has an offset between your input and output. If a right angle is necessary, bevel or hypoid gears are occasionally mounted on an inline planetary system. Worm and planetary combinations are uncommon because the worm reducer by itself delivers such high adjustments in speed.