Mechanical Gearbox Research Articles

Electromagnetic performance analysis of the umbrella shaping inner rotor coaxial magnetic gear with dual modulation rings

The coaxial magnetic gear is a new type of noncontact transmission mechanism, which avoids the inherent defects of the mechanical gearbox due to gear meshing transmission. To study a coaxial magnetic gear (CMG) with high torque density and low torque ripple to replace the mechanical gear in the semidirect drive wind turbine, a novel umbrella shaping inner rotor CMG (US-CMG) with an auxiliary modulation ring is proposed in this paper. The novel structure adopts a CMG with a dual modulated ring to increase the electromagnetic torque. In addition, the magnetic block of the poled inner rotor is divided into three pieces magnetized by Halbach arrays, and the middle piece is umbrella-shaped to reduce torque ripple. Based on the topology of the US-CMG and the principle of the magnetic field modulation, the operation mechanism of the US-CMG is analyzed. A contrastive analysis among the US-CMG, Halbach magnetized dual-modulator CMG (HM-CMG), and surface-mounted CMG (SM-CMG) is established to identify the performance of the US-CMG. Compared with the SM-CMG, the results show that the electromagnetic torque of the US-CMG has increased by 65.46%, and the torque ripple of the US-CMG is 57.6% of that of the SM-CMG.

Design of Active Continuous Variable Transmission Control System with Planetary Gear

Planetary gearboxes have been employed in various applications due to their advantages of maintaining a high speed-reduction ratio, such as in wind power applications which have now become a prevailing green energy resource. A traditional power transmission machine of the wind turbine has a fixed gear-ratio mechanical gearbox for speed-increasing transmission. The purpose of this study is to propose an active continuous variable transmission (ACVT) control system with a planetary gear to apply to the wind turbine. The planetary gear holds three terminals, i.e., the ring gear, the planet carrier, and sun gear, and the motions of three terminals can be controlled purposely by the servomotors to achieve ACVT. The three different transmission types of the proposed ACVT can be operated. The dynamic characteristic of the planetary gear is expressed in block diagram form, and a pseudo derivative feedback feed-forward controller of the velocity control loop is designed for the required performance. The results can be used to verify the effect of the proposed ACVT with the planetary gear.

A Novel Algorithm for Hydrostatic-Mechanical Mobile Machines with a Dual-Clutch Transmission

Mobile machines using a hydrostatic transmission is highly efficient under lower working-speed condition but less capable at higher transport velocities. To enhance overall efficiency, we have improved the powertrain design by combining a hydrostatic transmission with a dual-clutch transmission (DCT). Compared with other mechanical gearboxes, the DCT avoids the interruption of torque transmission in the process of shifting without sacrificing more transmission efficiency. However, there are some problems of unstable torque transmission during the shifting process, and an excessive torque drop occurring at the end of the gear shift, which result in a poor drive comfort. To enhance the performance of the novel structural possibility of powertrain design, we designed a novel control strategy, which maintains the sliding in the torque phase and reduces the difference before and after the engagement, for the motor torque and the clutch torques during the shifting process, and then validated the control effect with model-based simulation. As a result, the control strategy employing clutch and motor torque control achieve a smooth shifting process since the drive torque is well tracked, and highly dynamical actuators are not required. As another benefit, only two calibration parameters are designed and actually needed to adjust the control performance systematically, even for any different sizes machines. Our research indicates the possibility to adopt dual-clutch in the field of construction machines.

Schemes of momentum/reaction wheels unloading by mechanical restructuring and gearbox for spacecraft

A new principle and linked schemes of reaction/momentum wheels unloading are proposed and constructed. This principle is based on the instantaneous restructuring and changing the mechanical system itself, when additional internal degrees of freedom become available. These releasing additional degrees of freedom correspond to additional rotors, which take “after unfreezing” their own opportunity to rotate. At the connection of additional “unfrozen” rotors to the main wheels by gear type, these rotors become involved in the rotation with opposite direction relatively to the main wheels rotation, and it instantaneously provides nulling the relative angular momentum. Then electric motors of additional rotors and wheels can start the process of the rotational energy recovery, which decelerates and unloads angular velocities of all rotors and wheels. The proposed principle of releasing additional degrees of freedom and reconfiguring internal mechanical multi-rotor subsystem allow to immediately change values and directions of the relative angular momentum. This changeable multi-rotor subsystem represents the multifunctional attitude control system, which can be figuratively called as a “gearbox”. As a part of the gearbox a special mechanical device is proposed, which represents a “gravitational damper” to unloading the total absolute angular momentum of spacecraft with the help of external gravitational torques.

Intelligent Machine Fault Diagnosis Using Convolutional Neural Networks and Transfer Learning

With the development of automated and integrated large-scale industrial systems, accurate and effective fault diagnosis methods are required to ensure the security and reliability of running mechanical equipment. Due to the time consumption and poor generalization performance of conventional machine learning-based methods, deep learning (DL)-based methods have wider application prospects due to their end-to-end architectural properties. However, in the DL models, problems such as a large number of trainable parameters, complicated hyperparameter tuning, and initialization instability increase the difficulty of model training and limit higher performance. To address these disadvantages of the DL method, we proposed a novel DL framework by applying convolutional neural networks (CNNs) based on the optimization of transfer learning (TL). TL can help the model achieve higher precision with less computational cost by transferring low-level features and fine-tuning high-level layers. In addition, data processing was implemented using continuous wavelet transformation (CWT) to convert vibration signals into 2-D images, and support vector machines (SVM) were employed to replace the fully connected layers for better classification. As a result, the proposed method was superior to the classical deep architecture trained from scratch. The performance of the proposed method is analyzed by presenting testing reports, convergence curves, and confusion matrixes. Moreover, experiments comprised of cross-domain diagnosis, simulated composite fault detection, and performance comparison on seven mechanical datasets, including bearings, gearboxes, and rotors, are presented. Based on these results, it can be observed that our method achieved the highest accuracy under various conditions.

Анализ проблем механических редукторов транспортных систем и их решение с помощью магнитного датчика

Objective: Increasing reliability of mechanical gearboxes using a magnetic sensor, which will sig nifi cantly increase the reliability of transport mechanisms and systems in general. Methods: An analysis of incidents covered in the media was carried out. Results: Conclusions are drawn about the consequences of failure of mechanical gearboxes. To prevent emergency situations caused by a breakdown of a mechanical gearbox, it is proposed to use a magnetic sensor, which allows carrying out analysis and diagnostics of the gearbox and its components during operation. A mathematical model of a magnetic sensor is compiled and a block diagram of a device for processing the output signal of the sensor modulator is presented. Practical importance: Failure of a mechanical gearbox is a common problem that leads to a stop of transport mechanisms and systems. Detection of a mechanical gearbox malfunction can signifi cantly reduce the cost of repairs, as well as prevent unexpected damage to the mechanism, which can lead to a complete stop of the transport system. The use of a magnetic sensor in the traction gearbox of an electric train will reduce the likelihood of a traction gearbox breakdown during operation and reduce the cost of repairs, increase the reliability of the traction drive, and also simplify the commissioning of new electric trains and traction gearboxes.

Power Plant for a 0.6­0.8 Class Mobile Vehicle Based on the T­16 Self­Propelled Tractor Chassis

The authors showed the necessity to develop a rear-wheel drive hybrid mobile agricultural vehicle with electric drive and power plant. (Research purpose) To develop and study a new kinematic scheme of a mobile vehicle based on a self-propelled tractor T-16 chassis, which provides increased reliability, comfortable working conditions for the operator, a significant improvement in the environmental situation, and better economic efficiency. (Materials and methods) The authors listed the advantages of the new hybrid vehicle kinematic scheme. They gave the comparative technical characteristics of a diesel engine and an asynchronous electric motor. They developed a new methodology for calculating gas turbine engine technical parameters and described the production process of an electric drive with a capacity of 11 kilowatts to drive the driving wheels. The authors gave a thermal design of the compressor parameters, turbine. They calculated the excess air ratio. According to the parameters obtained, a K27-145 turbocharger was chosen, which simultaneously served as a turbine and a compressor of a gas turbine engine. A kinematic diagram was created with a gas turbine electric generator, storage batteries, an asynchronous frequency-controlled motor and a mechanical gearbox. (Results and discussion) The authors proposed to use a mobile vehicle as a mobile power plant: an output socket with a voltage of 220-230 volts operated from an inverter connected to batteries; the second socket – with a three-phase voltage of 400 volts – from the generator of the power gas turbine plant. (Conclusions) It was proved that the proposed hybrid mobile vehicle design on a battery and a gas turbine was capable of operating throughout the entire working day, and to provide 16 horsepower of a diesel engine, it was enough to install an asynchronous electric motor with a capacity of 7.5 kilowatts. The authors calculated the compressor performance of the gas turbine engine, which was 0.178 kilograms per second. The geometric parameters of the combustion chamber and the technical characteristics of the turbocharger were determined.

МАГНІТОЕЛЕКТРИЧНИЙ ПЕРЕТВОРЮВАЧ ЕНЕРГІЇ МОРСЬКИХ ХВИЛЬ

To convert the energy of sea waves, the use of cylindrical (with a radial magnetic flux) three-phase magnetoelectric generators with a permanent magnet rotor using a mechanical gearbox to increase the rotor speed is considered. Given the real rotor motion, a mathematical model has been developed to calculate the distribution of magnetic fields in the gap of the generator, and functional dependences of the flux linkage of the winding and the electromagnetic moment of the generator on its design and the parameters of permanent magnets have been obtained. For the adopted design, the electromagnetic moment, the distribution of phase currents in the windings, the power and voltage of the generator are determined. A comparison is made of the energy performance of generators with a traditional float drive and using a ratchet to ensure one-sided rotation of the rotor. The expediency of using a ratchet generator to convert the energy of sea waves is considered. References 6, figures 7.

Operation of the Pumping System with Rods

Abstract The asynchronous electric motor is used in the electric stock industry. The inverter adjusts the speed of an asynchronous motor from level 0 to rated speed. An oil pumping plant comprises the bottom machine and the surface machine. The lower machine consists of the depth pump, gas and sand separator, extraction pipe, pump rods. The surface tool includes the pump unit and other equipment. In turn, the pumping unit consists of the rocker, mechanical gearbox, connecting rods, cranks and electric motor. In pump extraction processes, maximum engine speed and / or power is not required. Significant reductions in power consumption can be achieved by adjusting the engine speed with the help of a converter. This solution can reduce production costs and increase productivity by up to 50-60%. The paper is dedicated to studying the regulation of the asynchronous electric motor using a converter controlled by a Siemens PLC. The equipment used is didactic, being produced by the company ASTI Romania.

Design and validation of a self-powered device for wireless electronically controlled pneumatic brake and onboard monitoring in freight wagons

Electronically controlled pneumatic (ECP) brake system achieves better brake consistency because of fast braking command transmission, but the practical application is limited by the lack of power transmission in standard railway freight wagons. This paper presents the excitations analysis, design, modelling and experimental validation of a novel self-powered device (SPD) utilizing vertical mechanical energy of freight car for onboard power supply. The device with ball crew, mechanical motion rectifier, gearbox and generator converts the bi-directional vertical translation between the car body and bogie into the unidirectional rotation of generator. The electromechanical coupled model of SPD is established to predict the performance versus different load conditions and train speeds. A peak voltage of 29.3 V and an average power of 50.26 W with 16 Ω external resistance are obtained when the full-loaded vehicle speed is 100 km/h, which indicates the potential of single device to power the wireless ECP brake system and sensor nodes simultaneously. The experiments are carried out and the results are in good agreement with the simulations. Moreover, the SPD adapts well to the broadband characteristics of railcars vertical vibration. The experimental results show that an average power of 4.6 W is achieved even in unfavorable condition. This onboard SPD as distributed power supply in unpowered freight car will realize the popularization of more smart devices and improve the overall performance of heavy-haul trains with long group.

Magnetic Gears and Magnetically Geared Machines with Reduced Rare-Earth Elements for Vehicle Applications

This paper covers a new emerging class of electrical machines, namely, Magnetic Gears (MGs) and Magnetically Geared Machines (MGMs). This particular kind of gears/machines is capable of either scaling up or down the revolutions-per-minute to meet various load profiles as in the case of mechanical gearboxes, but with physical isolation between the rotating components. This physical isolation between the rotational components leads to several advantages in favor of MGs and MGMs over mechanical gearboxes. Although MGs and MGMs can potentially provide a solution for some of the practical issues of mechanical gears, MGs and MGMs have two major challenges that researchers have been trying to address. Those challenges are the high usage of rare-earth Permanent Magnet (PM) materials and the relatively complex mechanical structure of MGs and MGMs, both of which are a consequence of the multi-airgap design. This paper presents designs that reduce the PM rare-earth content for Electric Vehicles (EVs). Additionally, the paper will ensure having practical designs that do not run the risk of permanent demagnetization. The paper will also discuss some new designs to simplify the mechanical structure.

A Model-Based SHM Strategy for Gears—Development of a Hybrid FEM-Analytical Approach to Investigate the Effects of Surface Fatigue on the Vibrational Spectra of a Back-to-Back Test Rig

Transmissions are extensively employed in mechanical gearboxes when power conversion is required. Being able to provide specific maintenance is a crucial factor for both economics and reliability. However, although periodic transmission maintenance increases the systems’ longevity, it cannot prevent or predict sporadic major failures. In this context, structural health monitoring (SHM) represents a possible solution. Identifying variations of a specific measurable signal and correlating them with the type of damage or its location and severity may help assess the component condition and establish the need for maintenance operation. However, the collection of sufficient experimental examples for damage identification may be not convenient for big gearboxes, for which destructive experiments are too expensive, thus paving the way to model-based approaches, based on a numerical estimation of damage-related features. In this work, an SHM approach was developed based on signals from numerical simulations. To validate the approach with experimental measurements, a back-to-back test rig was used as a reference. Several types and severities of damages were simulated with an innovative hybrid analytical–numerical approach that allowed a significant reduction of the computational effort. The vibrational spectra that characterized the different damage conditions were processed through artificial neural networks (ANN) trained with numerical data and used to predict the presence, location, and severity of the damage.

Control of a Wind Power Plant with a Synchronous Permanent Magnet Generator and a Magnetic Variator

Currently, the use of wind power plants with magnetic speed reduction is beginning to develop in the world literature. Features of the application of these systems in combination with a wind power plant allows you to solve the issue of its interface with the electric power system. The controlled flexible connection between the turbine and the generator makes it possible to coordinate the control of the load angle of the synchronous generator. In this paper, we consider a developed controller that provides integrated control of a wind turbine with a magnetic variator with a variable pitch of the blade angle and a variable speed of rotation of the wind turbine. A promising direction for the construction of wind power systems is currently the use of electromagnetic variators as part of wind power plants. This work is devoted to the study of electric power systems that include wind turbines with electromagnetic variators. The variator is built between the wind turbine and the generator, instead of a mechanical gearbox. The high-speed change in the torque of the electromagnetic variator allows you to keep the speed of the generator. Due to the inherent non-linearity of the wind turbine and CVT, a set of operational and emergency modes was defined and then the controller was designed for each operating point. In addition, the aerodynamic torque and effective wind speed are estimated online and a planned variable schedule for the controller implementation is obtained. Was tested by simulating with MATLAB/Simulink

Optimization design of magnetic gear integrated PMSG using improved bat algorithm for wave energy conversion

The magnetic gear integrated permanent magnet synchronous generator (MG-PMSG) can reduce the acoustic noise and mechanical loss, which are caused by the mechanical gear box. It also has the merits of increasing efficiency and reducing system volume when it is used for wave energy conversion system. In this paper, an improved bat algorithm (BA) based on velocity weighting factor is proposed. The improved BA is applied for the optimization design of permanent magnet (PM) to reduce the cogging torque of MG-PMSG. The numerical model is constructed by response surface methodology (RSM). The influences of key pole shape parameters on cogging torque were investigated, including the eccentric distance, the pole-arc coefficient and the permanent magnet thickness. A global optimization design is then carried out by using the improved BA, so that the magnet dimensions corresponding to the optimal cogging torque are obtained. Finally, the performances of the MG-PMSG with the optimized permanent magnet are analyzed by finite element method. Results show that cogging torque, steady torque ripple and back electromotive force (EMF) waveform distortion of the optimized MG-PMSG are reduced.

Analysis of Electromagnetic Performance of Modulated Coaxial Magnetic Gears Used in Semi-Direct Drive Wind Turbines

Wind turbine is a key device to realize the utilization of wind energy, and it has been highly valued by all countries. But the mechanical gear transmission of the existing wind power device has the disadvantages of high vibration and noise, high failure rate, and short service time. Magnetic field modulation electromagnetic gear transmission is a new non-contact transmission method. However, the conventional modulation magnetic gear has low torque density and torque defects with large fluctuations. In order to overcome the gear transmission problems of the existing semi-direct drive wind power generation machinery and improve the electromagnetic performance of the traditional magnetic gear transmission, this paper proposes a new transmission scheme of a non-contact semi-direct drive wind generator with a surface mount Halbach array modulated magnetic gear method, and considers the electromagnetic properties of the semi-direct drive modulation magnetic gear of the wind turbine. The finite element software is used to construct the model of the surface-mounted Halbach array magnetic gear and the conventional gear, analyzed the distribution of magnetic field lines of the two magnetic gears, calculated the air gap magnetic flux density of the inner and outer air gap, and obtained the main harmonics of the inner and outer air gap magnetic density; calculated the static torque and steady-state operating torque of the inner and outer rotors in the model, compared the air gap flux density, harmonics and torque of the magnetic gears. The simulation results show that the magnetic field modulation type magnetic gear of the surface mount Halbach array magnetic gear method improves the magnetic induction waveform of the inner and outer air gap, reduces the pulse torque fluctuation, and has a 60% higher static torque. Applying it to semi-direct drive wind power generation equipment not only overcomes the shortcomings of mechanical gears, but also has higher electromagnetic performance. Therefore, the surface-mounted Halbach array modulated magnetic gear can be used to replace the mechanical gearbox in the semi-direct drive wind power generation equipment.

Manyetik Dişli Sisteminin Sonlu Elemanlar Yöntemi ile Analizi

The magnetic gear system works with magnetic forces obtained with the help of permanent magnets and has a structure that can be an alternative to classical gear systems. In order to transmit torque between the input and output shaft, unlike conventional gears, there is a transmission without mechanical contact in the magnetic gear system. Therefore, friction is eliminated. Elimination of friction means that magnetic gear systems operate at much higher efficiency compared to conventional gearbox systems. Since the movement and torque transmission in magnetic gear systems occur without contact, it never requires lubrication and problems arising from lubrication do not occur. In conventional mechanical gearbox systems, the conversion rate is determined by the number of teeth used. Similarly in magnetic gear systems, the number of permanent magnets used determines the conversion rate. In this study, a magnetic gear system with a coaxial structure was designed and its electromagnetic analysis was made with the finite element method. Axial torque values at certain speeds in the input shaft and output shaft were obtained as a result of finite element analysis depending on time.

Simulation of Vibration Propagated by Rolling Element Bearings in Mechanical Gearbox

Simulation of Vibration Propagated by Rolling Element Bearings in Mechanical Gearbox

A comparison of conventional and modified vector control strategies for controlling transient currents and voltage dips in grid‐connected wind and photovoltaic hybrid system

AbstractA comparison of conventional and modified vector control strategies for controlling transient currents and voltage dips in grid‐connected wind and photovoltaic (PV) hybrid system is the purpose of this paper. The wind system is composed of three‐bladed rotor with a corresponding mechanical gearbox, a doubly fed induction generator, two power converters (rotor side converter [RSC] and grid side converter), a DC‐link capacitor that put with PV generator, and a grid filter. The big difficulty encountered for a wind and PV hybrid system is to withstand the voltage dip to avoid severe unbalanced grid voltage and transient currents that can damage the RSC. Simulation results show that with the new control, the wind and PV hybrid is able to eliminate large unbalanced grid voltages dips. The non‐negligence of the stator flux is taken into account of the modified control. Oscillation of rotor currents and overvoltage in the DC bus are low by the modified control strategy. The modified vector control constitutes a good alternative solution to overcome the problem introduced by voltage dips.

Techno-economic analysis of a hydraulic transmission for floating offshore wind turbines

Mechanical gearboxes have one of the highest failure rates of wind turbine components while being one of the most expensive parts to replace or service. They are easily fatigued and have a low power rating relative to their size and mass. In this article, hydraulic transmissions are proposed as an alternative to mechanical drive trains and their feasibility has been established, particularly for offshore wind turbine applications. Here, we provide an in-depth analysis regarding the techno-economic benefits of replacing the mechanical gearbox with a hydraulic transmission in an offshore system. Our analysis shows that hydraulic transmissions are particularly beneficial for offshore applications: (i) relocating 35.3% of the nacelle mass to the base, thus moving the center of gravity toward the ground level, (ii) diminishing operation and maintenance costs, and (iii) replacing now-redundant power electronics. These three benefits contribute to saving between 3.92 and 18.8% on the Levelized Cost of Electricity for average cost offshore wind turbines.

Methods of the driver’s activity when fulfilling the tasks in emergency

The article deals with the algorithm of the vehicle driver control activity using the method of logic-probabilistic modeling. When performing military automobile transporting in conditions of intense traffic flow, in conditions of performance of military-combat tasks the driver undergoes a significant amount of visual and auditory influences, the frequency of which increases significantly in situations that can cause incidents of traffic accidents. The driver is the operator of the system «driver-car-road-environment», the service processes are mainly reduced to the reception and analysis of operational information, decision-making that controls the actions and control of their implementation. Lack of time and necessary information, intense and uneven information load while driving the vehicle leads to the development of the driver psychological stress. At the same time, the important psycho-physiological characteristics of the driver deteriorate substantially, such as a complicated motor reaction, characterized by the average duration of response time, emotional stability and stability of attention. The factors that determine the possibility of traffic accidents, among others, include driver's level of qualification, his physical and psycho-physiological characteristics. In this case, the term of the reaction of the driver, which is an integral indicator of the visual-motor system, is of great importance. A long reaction time increases the risk of road traffic accidents which can cause both material and human losses. The car is the object of management in the «driver-car-road-environment» system. In recent years there is a continuous increase in the number of cars and improving their speed characteristics. In this regard, the safe operation of a modern car requires the use of modern pedagogical tools and training methods for drivers. In these conditions, not the knowledge of its design is essential for the effective operation of the car, but the knowledge of its properties as an object of management, understanding the role of automatic systems, the ability to perform operations with the control of these systems, the ideas about changing the properties of the car in the case of the failure of such systems. The safety of the vehicle driving depends on the psychological characteristics of drivers, the ability to perceive unexpected information quickly and respond to itadequately. Vision, hearing and touch are the most important channels of perception of information. The level of safe driving depends on the characteristics of mental processes, such as: attention, memory, thinking, psychomotor, sensation and perception, since they play an important role in the vehicle driving. Estimation of the driver's activity in terms of the degree of complexity of the driving of motor vehicles of standard sizes and the nature of the route must be complex, taking into account the design features of the control of vehicles and conditions of movement on the route. It must be carried out in different ways and take into account its various components. During the work the driver performs a large number of actions which seem to be quite simple such as pedaling, pressing the levers, turning on and off the toggle switches, turning the steering wheel. All these driving actions are carried out in a certain order, depending on typical traffic situations. During the operation, the driver performs a large number of motor activities, and the amount of effort applied to the control of the car, is quite large and different. Therefore, it is advisable not just to take into account the typical actions of the driver, but to estimate them by the amount of the efforts applied to the control of the car. A significant disadvantage of this method is the disregard for technical factors that affect the complexity of the driver activity of vehicle management (overall length, gross vehicle weight, type of gearbox design). It should also be noted that the nature of the connection between the complexity of the official driver activity and fuel consumption can be different. For example, considering the movement of a vehicle with a variable longitudinal profile of the traffic route, it can be noted that fuel consumption is greater when moving on the rise, and the difficulty, on the contrary, when driving on the descent. Comparison of fuel consumption and complexity of vehicle control processes, equipped with a hydro mechanical gearbox and conventional mechanical gear shows that fuel economy is less, and the complexity of the driving is lower. The use of methods of algorithmic analysis in road transport is a scientifically grounded method, an analysis of working processes with the introduction of their quantitative characteristics, having a certain psycho physiological content. The principle of this method is to decompose the work process into qualitatively different elemental components. The work of the car driver is presented as a logical activity, consisting of a set of actions and operational units of information. Examples of application of the algorithm and evaluation of the driver's activity on the control of the vehicle are considered.