Planetary Gear Research Articles

Mechanism Isomorphism Identification Based on Decision Tree Algorithm and Hybrid Particle Swarm Optimization Algorithm

Mechanism isomorphism identification is a typical quadratic assignment problem similar to traveling salesman and job-shop scheduling. For the complex mechanism with more components, common methods of isomorphism identification may fail due to low solving efficiency and reliability. Based on the decision tree algorithm and hybrid particle swarm optimization (HPSO) algorithm, the global-local search method is proposed to identify isomorphism of mechanisms. More precisely, based on the intrinsic relationship between links and vertices in the mechanism, the decision tree algorithm globally searches the characteristic path with mapping properties of different mechanisms. On this basis, HPSO algorithm combines genetic algorithm with particle swarm optimization algorithm to find the exact global optimal solution instead of local optimal solution. Some complex cases such as 14-link kinematic chains, 18-vertex topological graphs, and 8-vertex planetary gear trains are used to evaluate the efficiency and reliability of the proposed method. Results show that the proposed method can accurately identify isomorphism of mechanisms in a relatively short time. It can improve the solving efficiency of isomorphism identification in structural synthesis.

A study of the dynamic transmission efficiency of the cycloid pin gear pair under dynamic characteristic analysis

Transmission efficiency is one of the main technical indicators for evaluating the transmission performance of a cycloid pin gear planetary reducer. The cycloid pin gear pair is a crucial component of such a reducer. When the design parameters of the cycloid pin gear pair are determined, its transmission efficiency is often considered a constant, which significantly hinders accurate calculations of the transmission efficiency of the cycloid pin gear planetary reducer. To address this issue, this paper introduces a dynamic transmission efficiency analysis method specifically tailored for the cycloid pin gear pair, grounded firmly in dynamic characteristic analysis. Firstly, a comprehensive and meticulous dynamic performance analysis method is proposed for the cycloid pin gear pair, enabling precise calculations of dynamic transmission efficiency. Secondly, an optimization framework is introduced, with a primary focus on enhancing the transmission efficiency of the cycloid pin gear pair. A transmission efficiency assessment model is established as the objective function, which takes into account the pressure angles of both the driving gear and the driven gear at the meshing position. To demonstrate the practical utility and effectiveness of these methodologies, an illustrative example is presented. The results obtained from this example underscore a remarkable improvement in the overall transmission performance of the system. This enhancement is characterized by substantial gains in transmission efficiency and effective vibration control, highlighting the significance and practicality of the proposed approaches.

Erratum to “Fault feature detection of planet gear in multi-stage planetary gearbox based on angle compensation synchronous averaging”

Erratum to “Fault feature detection of planet gear in multi-stage planetary gearbox based on angle compensation synchronous averaging”

Experimental Verifications of Uninterruptible Power Supply Using a Flywheel Motor-generator and a Planetary Gear

Experimental Verifications of Uninterruptible Power Supply Using a Flywheel Motor-generator and a Planetary Gear

Dynamic analysis of two-stage steering reducer for electric vehicle based on ROMAX

Abstract. With the rapid development of electric vehicles in the modern market, the efficiency and performance requirements of electric vehicle transmission systems are getting higher and higher. As an important part of the electric vehicle reducer, the steering reducer can make full use of the advantages of the two-stage deceleration transmission, achieve more efficient power transmission, and improve the acceleration performance and driving performance of electric vehicles. This paper aims to design a two-stage steering reducer for an electric vehicle, which adopts planetary gear transmission type. Firstly, the working principle of the electric vehicle steering reducer is analyzed, and the overall design scheme of the reducer is drawn up. Secondly, the transmission system parameters of the reducer are designed and calculated, including transmission ratio distribution, tooth number ratio calculation, etc. Secondly, the transmission structure of the reducer is designed, including input shaft, output shaft, first planetary gear train, second planetary gear train, reducer shell, bearing, etc., and the reducer model is drawn by three-dimensional software Solidworks. Finally, the strength and deformation check analysis of the two-stage reducer is carried out by using the finite element software ROMAX to evaluate the performance of the designed reducer under this working condition. The full text design has a certain reference, and can be applied to other electric vehicle reducer design to provide theoretical guidance.

The effect of a 120 kg pontoon mass on the wave energy converter device due to heaving

The environment is negatively impacted by the use of fossil fuels as a source of electricity. Using sustainable ocean wave energy is one way to replace fossil fuels and maximize the usage of natural energy. Electrical energy is produced from mechanical energy by ocean waves. An apparatus for converting wave energy from the ocean is needed to absorb it. The wave energy converter uses the up-and-down action of a chain on a pontoon to rotate a generator, producing electrical energy. The mass of the pontoon and the force of the ocean waves that excite it both have an impact on its vertical movement. Thus, the impact of pontoon mass on the wave energy converter is examined in this research. Both a planetary gear system and one without were used in the investigation. The voltage and current obtained at a wave height of 35 cm were 2.28 Volts and 0.160 A, respectively, without the planetary gear and 160.41 Volts and 13.95 A, with the planetary gear. Furthermore, an evaluation of the wave energy converter machine's performance was carried out. Using a planetary gear and a wave height of 13 cm, the second experiment's minimum power production was 212.63 Watts, while the sixth experiment's maximum power output was 2237.72 Watts with a wave height of 35 cm. In the second experiment, the generator without a planetary gear produced 0.0327 watts of power with the same wave height, and in the sixth trial, the generator produced a maximum of 0.3648 watts with a 35 cm wave height. As a result, utilizing a generator with a planetary gear is preferable to using one without one

Study on the effect of pitching on wave energy converter devices due to a spring constant of 980 N/M

Having enough energy is crucial to living a healthy and fulfilling life. Energy is necessary for many of the actions and tasks that individuals carry out regularly. To increase national resilience and enhance the welfare of its citizens, Indonesia is thought to be a good place to use renewable energy through the development of its natural resources. The Wave Energy Converter is one of the energy producers (WEC). The Wave Energy Converter is a machine that uses the up-and-down motion of a chain through a pontoon to drive the rotation of a solenoid in a generator to produce electrical energy. The component that produces energy is the vertical movement of waves. Thus, the impact of the spring constant on ocean waves is examined in this work. Both planetary and non-planetary approaches were used in this study. Based on the research objectives and the experimental results on the pitching motion performance of the Wave Energy Converter machine, it can be concluded that the power without planetary gear in the analysis of potential energy and sea data identification is 0.43 Volts, and the highest is 4.2 Volts. The RPM range is 78.18 RPM at the minimum and 91.45 RPM at the maximum. 0.021 amps is the minimum and 0.043 amps is the maximum current value. The power range for planetary gear potential energy analysis and sea data identification is 58.5 volts to 168.36 volts. The RPM range is 78.18 RPM at the minimum and 91.45 RPM at the maximum. 1.93 amps is the least current value, and 14.01 amps is the maximum

Nonlinear dynamics of continuous steady-state tunable mechanical metamaterials based on planetary gears

Mechanical metamaterials with tunable mechanical properties have received extensive attention. In this work, a continuous steady-state metamaterial with tunable mechanical based on planetary gear cells is designed. Firstly, the excellent tunable properties of metamaterials are studied, which shows the designed metamaterials has a wide range of programmable stiffness and a significantly tunning band gap. The configuration relationship between tunability and structural parameters is analyzed. Then, a rigid-flexible coupling nonlinear dynamic model of planetary gear metamaterials is established and the dynamic characteristics of planetary gear metamaterials in the process of dynamic tunning are explored by numerical simulation. Moreover, the distribution characteristics of the system vibration response with the coupling parameter plane are disclosed, and the influence of the system dynamic parameters on its bifurcation characteristics and stability under coupling excitation is explored. Furthermore, an improved non-iterative cell mapping method is used to analyze the dependence of the vibration response of the system on the initial conditions. This work shows that the planetary gear metamaterials have a wide range of stiffness tunability and significantly variable band gap interval. Under the influences of internal and external excitations, the system exhibits various dynamic characteristics. The dynamic characteristics of flexible construction are mainly affected by structural parameters, and the dynamic characteristics of rigid construction are affected by multiple sets of coupling parameters and initial conditions.

A study on load sharing characteristics of the planetary gear train system with cracked gears

Load sharing characteristic is very important for the reliability of the planetary gear train. Cracked gears can make the load sharing performance become worse. Nevertheless, previous studies have not paid enough attention to the influence of cracked gears on the load sharing behavior, when compared with the impact of multiple factors under healthy condition. An 18 degrees of freedom dynamic model for the spur planetary gear train is established based on the centralized parameters theory in this paper. The influences of cracked gears on the load sharing behavior are investigated, which include the cracked sun gear, the planet gear containing cracked side meshing with the sun gear, the planet gear having cracked side meshing with the ring gear and the cracked ring gear. Additionally, the sensitivity analysis of the external and internal load sharing behavior to different cracked components is conducted. The results indicate that the load distribution becomes more uneven with the propagation of crack in the sun gear and ring gear, while the change regulation is different for each cracked planet gear. Moreover, the load sharing characteristic of the external meshing is more sensitive to the cracked sun gear and the planet gear 1, which has the crack side meshing with the ring gear. While the load sharing characteristic of the internal meshing is more sensitive to the cracked ring gear and the planet gear 3, which owns the crack side meshing with the ring gear than others. The output of this paper will be useful for the crack fault diagnose and fault source identification of the planetary gear train system.

Investigations on Spin Power Losses Generated in a Planetary Gear Set Using Thermal Network Method

Investigations on Spin Power Losses Generated in a Planetary Gear Set Using Thermal Network Method

Power Losses of Oil-Bath-Lubricated Ball Bearings—A Focus on Churning Losses

This study investigates the power losses of rolling element bearings (REBs) lubricated using an oil bath. Experimental tests conducted on two different deep-groove ball bearings (DGBBs) provide valuable insights into the behaviour of DGBBs under different oil levels, generating essential data for developing accurate models of power losses. Observations of the oil bath dynamics reveal the formation of an oil ring at high oil levels, as observed for planetary gear trains, leading to modifications in the oil flow behaviour. The experiments demonstrate that oil bath lubrication generates power losses comparable to injection lubrication when the oil level is low. However, as the oil level increases, so do the power losses due to increased drag within the bearing. This study presents a comprehensive model for calculating drag losses. The proposed drag power loss model accounts for variations in oil level and significantly improves loss predictions. A comparison of existing models with the experimental results shows good agreement for both bearings, demonstrating the effectiveness of the developed model in accounting for oil bath height in loss calculations.

Investigation of contact ratio and dynamic characteristics of non-circular planetary gear train in hydraulic motor

As a basic component of the non-circular gear hydraulic motor (NGHM), the non-circular planetary gear train (NPGT) offers a number of advantages, including low velocity, high output torque and compact design. Two different types of NPGT pitch curves have been designed using the 4–6 type of NGHM as an example. Aiming at two kinds of pitch curves, the contact ratio solution methods for the planetary gear meshing respectively with the sun gear and the inner gear ring are proposed. A comparative analysis of an integrated pitch curve design and a segmented pitch curve design is conducted to evaluate the effects of varying addendum coefficient (AC) and tool tooth profile angle (TTPA) on the contact ratio. Furthermore, the influence of load, velocity, and contact ratio on the dynamic characteristics (DC) of the NPGT with a segmented pitch curve is investigated through dynamic simulation. The results show that AC and TTPA significantly affect the contact ratio, with an increase in contact ratio observed as TTPA decreases and AC increases. Additionally, the load has a notable impact on the dynamic meshing force and its fluctuation. A higher contact ratio is associated with greater transmission stability in the gear train. This study provides a theoretical foundation for the design and optimization of NGHMs, and expands the potential application of contact ratio effects on NPGTs in this field.

Nonlinear performance of aerospace face gear-planetary gear transmission system under multi-factors including the effect of temperature

Face gear-planetary gear transmission system combines the advantages of both planetary and face gears. And has enormous advantages in the aerospace field. The meshing of gear teeth generates heat through friction, resulting in thermal deformation and affects nonlinear dynamic characteristics. Exploring the temperature effect on the nonlinear dynamics of the transmission system of face gear-planetary gear is of great significance. Considering the temperature variations effect and time-varying meshing stiffness, tooth side clearance as well as meshing error, a nonlinear dynamic model of the face gear-planetary gear system is established. The nonlinear dynamic characteristics of the system were described by maximum Lyapunov exponent diagram, phase diagram, bifurcation diagram et al. The findings indicate that the effect of temperature variations on the gear system is related to the values of the time-varying mesh stiffness coefficient and mesh damping ratio. When the mesh damping ratio is small, the influence of temperature changes on the bifurcation characteristics of the system is more obvious. As the time-varying mesh stiffness value increases, the temperature rise gradually stabilizes in the range of 15°C to 42°C; Under certain temperature changes, as the meshing damping ratio and time-varying meshing stiffness coefficient increase, the face gear planetary gear system gradually tends to stabilize.

Innovations in Engineering and Technology of Worm-Type Gears

Relatively small changes in engineering and technology of traditional established products turn over time into a series of milestones that determine both technical characteristics and production methods, and as a consequence - the competitiveness of the final product. Accordingly, it is relevant to periodically look at the evolution of the accumulated solutions and make some conclusions on it. For this purpose, the paper reviews innovations in design and production of worm-type gears obtained in Izhevsk scientific school in the field of gears for the last two decades: spiroid gears operating at low rotational speeds and transmitting high loads, leading to plastic deformations due to compactness of gears; spiroid gears with small gear ratios (3...8) competing with more expensive in production bevel and hypoid ones; worm gears with steel hardened gearwheels with increased strength and manufacturability; planetary spiroid gears providing extremely high gear ratio, improved methods and techniques of design and preproduction of gear cutting. The paper presents the review of innovations in design of worm-type gears made in Izhevsk scientific school in the field of gears for the last two decades: spiroid gears for cases of low speeds and small gear ratios, worm gears with steel hardened gearwheels, planetary and spiroid gears, improved methods and techniques of design and preparation of gear cutting.

Simulation and validation of the transmission error, meshing stiffness, and load sharing of planetary spur gear transmissions

Although the load sharing between planets of sequentially phased planetary gear transmissions has been studied in the past, the required solving techniques based on the Finite Element Method result in long time consuming and high computational cost. This limits the possibilities of undertaking extensive studies that take into consideration a high number of cases allowing optimal solutions to be sought or general conclusions drawn. In addition, the determination of the curves of transmission error, time-varying mesh stiffness, and load sharing among tooth pairs in simultaneous contact are also complicated. In this work an analytical model has been developed for the simulation of the time-varying mesh stiffness, quasi-static transmission error, and load sharing ratio between planets and tooth pairs of planetary spur gear transmissions. It is based on similar models for external and internal spur gears previously developed and has been validated by comparison with a hybrid model based on the Finite Element Method and theoretic-experimental correlation.

Creation of self-aligning multisatellite planetary gears

In this study, we aim to identify shortcomings in the operation of multisatellite planetary gearboxes and to justify improved designs of planetary self-aligning mechanisms, which allow torque to be transmitted through all installed satellites. To that end, we studied a domestic planetary three-satellite MPZ gearbox installed on a magnetic separator, designed for wet separation of strongly magnetic ores and materials into magnetic and non-magnetic products, and a planetary gearbox of a special structure. 3D models of the classical three-satellite and single-sliding self-aligning gearboxes were constructed in the 3D module of the T-Flex CAD software. The performance of the mechanisms was evaluated by structural analysis and Chebyshev’s mobility formula. The constructed 3D models were used to study the engagement process of the classical three-satellite and single-sliding self-aligning gearbox. The latter is distinguished by the presence of two levers, which are introduced additionally to three satellites. During the research, the lateral clearance between the pairs of satellite teeth and center wheels was accepted according to GOST 1643–81. The conducted analysis of contacts at rotation of the central driving wheel by 30°, 110°, 200°, and 310° established further designing of the applied planetary gears to be inexpedient due to impossibility of realization of power transfer simultaneously through all satellites. The main disadvantage of the operation of multisatellite gearboxes was found to be the requirement for the side clearance selection, which should ensure the operability of the transmission at the moment of motion transfer. When designing multi-satellite single-slide selfaligning planetary mechanisms, additional levers should be introduced into the structure, the number of which should be equal to the number of satellites. Hence, the use of self-aligning planetary gears makes it possible to reduce the dimensions due to the uniform distribution of the transmitted torque, since the calculated value of the torque can be reduced by the number of satellites. This allows the gears to be adapted to the working loading conditions, which significantly improves the performance of the entire machine or unit.

Numerical investigation of vibratory response of planetary gear sets and modulation effects induced by carrier rotation

In geared system, the main source of excitation is generated by the mesh process itself. Depending on the dynamic conditions involved, the system may present a variety of problems, ranging from acoustic nuisance to system failure. Predicting and controlling the mesh process at an early design stage is a key point to avoid such issues. The problem is complex, mainly due to its multi-scale nature. Indeed, the vibroacoustic behavior of geared systems (on the scale of a meter) depend on the local micro-geometry of the teeth (of the scale of a micron), associated with the transmission error. Moreover, the problem is parametric in nature, due to the periodic fluctuation of the mesh stiffness. These parametric internal excitations generate dynamic mesh forces which are transmitted to the housing through wheel bodies, shafts and bearings. In the case of planetary gear sets, the numerical prediction presents a complementary challenge as, in many application, the carrier rotation modulates the housing vibration response, at its rotational frequency. This paper present an original simulation process to deal with modulation effects in planetary gear systems.

Effect of Planetary Gear Set Designs on Thrust Bearing Power Loss in Automatic Transmission

Effect of Planetary Gear Set Designs on Thrust Bearing Power Loss in Automatic Transmission

Effect of meshing-induced deformation on lubrication for journal planet gear bearings

To increase the power density and reliability of wind turbine gearboxes (WTGs), journal planet gear bearings (JPGBs) are increasingly employed in their low-speed planet stages. Except for the pressure- and temperature-induced deformations, the JPGB is also structurally deformed by the gear pair meshing in this application, complicating the lubrication and deformation characteristics. Considering the above meshing-induced deformation, a thermo-elasto-hydrodynamic (TEHD) model is proposed for the JPGB, whose deformation is predicted using a self-programmed procedure based on the finite element method (FEM). Besides, this model is verified through a lubrication experiment of the JPGB in the WTG. It is found that the appropriate meshing-induced deformation, varying periodically in the meshing process, can improve the TEHD and misalignment behaviors of the JPGB due to the load-carrying region expansion or twice hydrodynamic action. This phenomenon becomes increasingly obvious with increasing the WTG's input power and the planet's inner radius.

Research on the Energy Management Strategy of a Hybrid Tractor OS-ECVT Based on a Dynamic Programming Algorithm

The multi-degree-of-freedom characteristics of the planetary gear electronic continuously variable transmission (ECVT) configuration in series-parallel hybrid tractors impose more complex requirements for energy management strategies under variable load conditions. For a high-power hybrid tractor, this paper takes the hybrid tractor output-split (OS)-ECVT configuration as the research object and describes the principles of stepless transmission and power-splitting within the configuration. In order to improve the fuel economy of high-power hybrid tractors and the running status of power components, an energy management strategy focused on ploughing conditions based on the Bellman minimum dynamic programming (DP) algorithm is proposed in this paper. Second, equivalent fuel consumption is selected as the performance index for energy-saving control, and the solving principle of the energy management strategy based on the dynamic programming algorithm is established to facilitate the resolution process of the energy management strategy. Finally, the energy-saving control simulation is completed under ploughing conditions. The results show that compared with the energy management strategy based on the optimal operating line (OOL), the energy management strategy based on DP fully utilizes the benefits of low-cost electric energy and enables the hybrid power system to have a wider range of stepless transmission performance. In addition, the hybrid power system has the advantages of enhanced decoupling of speed and torque, higher efficiency, and more economical secondary energy conversion. As a result, the whole machine has enhanced power-split performance, greatly improving the running conditions of the power components. The equivalent fuel consumption values of the energy management strategies based on DP and OOL are about 3.1238 L and 4.2713 L, respectively. The equivalent fuel consumption based on DP is reduced by about 26.87%, which effectively improves the fuel efficiency of hybrid tractors.