最新刊期
卷 48 ， 期 7 ， 2024
- 摘要：The complex flow field in the high-speed gearbox affects the transmission efficiency and performance of the transmission system by affecting the gear oil injection lubrication characteristics. Therefore, it is necessary to carry out research on the two-phase flow field and lubrication characteristics of high-speed gear oil injection considering the complex flow field of high-speed gear box and the baffle structure. Based on the computational fluid dynamics method, a two-phase flow field analysis model of high-speed helical gear oil injection lubrication is established, and the two-phase flow field distribution characteristics are analyzed. On this basis, the effects of injection parameters such as injection speed, injection angle, axial injection angle, and gear baffle on the injection lubrication characteristics are further studied. The results show that the oil on the surface of high-speed helical gear inclines to one side. By increasing the injection speed or adding the positive axial angle, the oil deflection and the lubrication effect can be improved. The gear baffle plays a role in guiding the oil, and the setting of axial baffle is conducive to increasing the oil on the tooth surface. This study provides a basis for the study of two-phase flow field distribution characteristics of high-speed gearboxes and the optimization design of oil injection lubrication.关键词：High-speed gear;Oil injection lubrication;Computational fluid dynamics;Gear baffle
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：In order to improve the braking energy recovery rate, the braking effect required by drivers with different braking intentions under different working conditions is considered, and a braking control strategy of four-wheel-drive electric vehicles is proposed. Firstly, according to conventional braking conditions, control strategies are designed from the perspectives of braking energy recovery rate, stability and safety based on conventional braking intention recognition. Secondly, according to different coasting braking intentions under coasting conditions, whether and when the electric force intervenes are determined, and the size of the braking force from motors is calculated according to the driver's required coasting distance. Thirdly, the external characteristics of the front and rear motors are obtained by bench tests, and the optimal utilization efficiency model of the front and rear motors is established. Finally, Carsim and Simulink are used for co-simulation analysis. The results show that the braking energy recovery rate is improved by 13.64 percentage points compared with the parallel control strategy in new European driving cycle （NEDC） condition. It can effectively identify the driver's required coasting distance under coasting conditions and improve the vehicle's coasting economy.关键词：Four-wheel-drive electric vehicle;Braking intention recognition;Dual-motor external characteristics;Braking energy recovery;Control strategy
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：Fault mechanism is the basis of fault diagnosis, and modelling is an important means to investigate the fault mechanism. The existing research on modelling of planetary gear systems mainly includes the dynamic modelling and the phenomenological modelling. The dynamic modelling is difficult to be established and mainly focuses on dynamic characteristics of a single component. The phenomenological modelling can describe a system from a macroscopic perspective, which is beneficial for the fault diagnosis of planetary gear systems. Root crack is a common fault type in planetary gear systems. In this study, phenomenological modelling of vibration signals of planetary gear systems under normal and cracked conditions are established. Firstly, based on the theory of impact dynamics, the meshing impact force when the gear tooth enters into meshing is calculated, and its effect on the dynamic load factor is simulated. Secondly, phenomenological modelling of vibration signals considering the meshing impact is established, and model responses of planetary gear systems under different health conditions including normal, cracked sun gears and cracked planet gears are obtained. Finally, the model responses are analyzed using the statistical indexes such as root mean square and kurtosis, etc., and the sensitivity of each statistical index in reflecting the crack fault is compared. The comparison results show that the kurtosis can be used as one of the effective indexes to reflect the tooth root crack in planetary gear systems.关键词：Fault mechanism;Planetary gear system;Fault diagnosis;Root crack;Phenomenological modelling
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：The fuel economy of hybrid electric vehicles largely depends on the transmission system parameters and energy management strategy. However, due to the interaction between the transmission system parameters and energy management strategies on the optimization of fuel economy, and the difficulty in balancing the real-time and global optimality of energy management strategies, there is still a lack of an effective implementation method. This study takes the hybrid electric mining truck as a research object, establishes the mathematical model of the whole vehicle, takes reducing fuel consumption as the goal, establishes a collaborative optimization model that comprehensively considers the interaction between transmission system parameters and energy management strategies, and combines particle swarm optimization (PSO) algorithm and dynamic programming (DP) algorithm to build a two-layer interactive optimization algorithm to eliminate the interaction between transmission system parameters and energy management strategies. The optimal energy distribution can be achieved while optimizing the transmission parameters. On this basis, in order to solve the problem that the DP algorithm is difficult to realize online control, the optimal solution of DP energy management corresponding to the optimal transmission parameters is integrated, an effective method to extract the optimal control rules of DP is designed, and an energy management strategy based on the optimal control rules is established to realize online control of hybrid electric mining trucks. Thus, the integrated realization method of the coordinated optimization of transmission system parameters and energy management strategy, as well as the optimal energy management real-time control strategy, is established. The obtained optimal transmission system parameters and corresponding optimal energy management real-time control strategy are simulated and verified on the Stateflow-AMESim joint simulation platform. The results show that the fuel consumption results obtained by this method are better than those obtained by DP optimization alone, and they are closer to the results obtained by PSO-DP optimization, indicating that the optimization method is effective and feasible.关键词：Hybrid mining truck;Transmission system parameter;Energy management strategy;Fuel economy;Joint optimization
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：Aiming at the problems of single structure form and limited transporting range of existing underwater vehicles, receiving and placing system, this study carries out comprehensive research on actuator configuration of the receiving and placing system with the help of relevant graph theory, and finally establishes 14 actuator configuration libraries of the receiving and placing system. Firstly, the types of the planar nine-bar single-hinge mechanism are synthesized based on the method of blastogram insertion, and 40 kinds of monochrome topological maps are obtained. Secondly, based on 40 kinds of monochrome topological maps, a method for synthesizing planar nine-bar mechanism with only one type of complex hinge mechanism is proposed. By transforming the monochrome topological map and its specific markings, and generating feature array of the complex hinge mechanism according to certain rules, the mechanism isomorphism judgment and negative sub-link recognition are realized based on the feature array, and 83 kinds of bi-color topological maps are obtained. Then, based on the flat nine-bar single-color and two-color topological map and combining the operating characteristics of the collection system, six configuration screening conditions for the implementation mechanism of the collection system are proposed and 71 feasible configurations are selected. Finally, based on 71 feasible configurations and considering mechanism control, cost and aesthetics comprehensively, three configuration optimization criteria are proposed, and 14 optimal configurations are finally obtained. An optimum configuration is selected for motion simulation analysis. The results show that the actuator of the new placing system meets the operating conditions, the end integrated hoist can achieve far and near displacement and accurate positioning, and the rationality of the mechanism configuration design is verified.关键词：Graph theory;Multiple gemel;Configuration synthesis;Receiving and placing system;Underwater vehicle
- 23
- |
- 5
- |
- 0
发布时间：2024-07-22 - 摘要：Due to the characteristics of multi-tooth line contact, toroidal involute worm drive has the advantages of high bearing capacity and so on. However, due to increased constraints, it is more sensitive to manufacturing error and assembly error. To reduce the error sensitivity, this study proposes a modified toroidal involute worm drive based on the medium gear. The meshing geometry model between involute gears, medium gears and toroidal worms is constructed, and the local conjugate contact analysis method of space points of the drive pair is established. The spatial point-contact analysis method is developed, combined with numerical analysis and finite element simulation analysis, and the variation principles of meshing characteristics are revealed.The results show that the novel toroidal worm drive has lower error sensitivity, and can maintain the bearing capacity under high load. Based on a man-machine interactive heavy-duty robot rotary joint applied to 7 km automatic drilling rigs, a prototype of modified involute enveloping toroidal worm drive reducers is developed, and the correctness of theoretical analysis is verified.关键词：Toroidal worm drive;Meshing geometry;Medium gear;Error sensitivity
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22
Theory·Research
- 摘要：In the design of coaxial magnetic gears, the bridged modulating ring is proved to be an effective strategy for reducing the manufacturing difficulty and enhancing the mechanical strength of the structure. The design of modulating rings necessitates a comprehensive consideration of the factors including electromagnetic performances, mechanical strength, and manufacturing cost. This study investigates the design of bridged modulating rings employed in coaxial magnetic gears. By changing the design variables such as the thickness of the bridge, the proportion of modulation blocks, the number and diameter of clamping rods, a focused analysis is carried out to illustrate the variation pattern of the maximum torque of magnetic gears and the stress distribution in the bridged modulating rings with the change of these design variables, and a design method for bridged modulating ring is also proposed based on above analysis.关键词：Magnetic gear;Bridged ring modulator;Clamping rod;Mechanical stress;Maximum torque
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：Due to its natural characteristics, coaxial magnetic gears are still difficult to be directly applied to industrial robots. Some key basic characteristics such as torque density, transmission ratio, null-space, backlash and torsional stiffness, and stable working area are still insufficient. For this reason, this study takes the harmonic gear performance of the national standard type 14 as the reference object, uses the relevant electromagnetic theory and the analogy method to study and compare the related performance of the coaxial magnetic gear with the same space size and its numerical calculation method, stability and the integrated technology of servo motors and coaxial magnetic gears. It is pointed out that the lack of torsional stiffness is the key factor that restricts the use of coaxial magnetic gears in robots, and the research focus of the coaxial magnetic gear servo control for robots in the future is clarified.关键词：Coaxial magnetic gear;Null-space;Backlash;Torsional rigidity
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：The hinge position of the turnover mechanism directly affects the overall working performance of the mobile garbage compression device and the working life of each hinge point of the turnover mechanism. To improve the overall working performance of the turnover mechanism and the working life of each hinge point, Adams software is used to establish a virtual prototype model and conduct simulation to obtain the load of each hinge point of the turnover mechanism. Then, the static strain tester is used to test the turnover mechanism, and it is found that the virtual prototype model conforms to the actual situation and has verified the validity of the model. On this basis, through further analysis of simulation data, the maximum load and minimum transmission angle of hinge point A and C of the tilting mechanism are determined as the optimization objectives. The ideal point method is applied to construct a comprehensive evaluation function in Adams software and solve it optimally. Through comparing the data before and after the optimization, the maximum load of hinge point A of the tilting mechanism is reduced by 19.3%, the maximum load of hinge point C is reduced by 16.2%, and the minimum transmission angle is increased by 32.1%. Finally, the optimal design value of the hinge position of the turnover mechanism is determined, which can provide reference for the subsequent design and application of the turnover mechanism of the mobile garbage compression device.关键词：Turnover mechanism;Transmission angle;Ideal point method;Multi-objective optimization
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：In order to solve the problem of back pressure caused by the nursing bed during the back lifting process, a new type of back lifting mechanism that can link with the waist plate is innovatively designed. Firstly, the multi-link mechanism is used to realize the linkage of the waist plate during the back lifting process, and the triangular suspended area generated in the waist part during the back lifting process is filled, so as to provide support to the waist and reduce the back pressure. When the back is lifted, the raised waist plate acts as a cushion, which is more in line with the ergonomic requirements under the sitting state. Combined with the parameters of the body size, the back forces of the new back lifting mechanism and the traditional back lifting mechanism are analyzed and compared, and it is verified that the new back lifting mechanism can reduce the back pressure feeling. In addition, the kinematics analysis of the back lifting mechanism is executed, and the parametric modeling is carried out. Meanwhile, the size optimization design is carried out with the minimization of the maximal angular acceleration of the back plate as the optimization objective. Then, the dynamic simulation of the mechanism is carried out to obtain the maximum force in the movement process, which is imported into Ansys for statics simulation to verify the safety and stability of the back lifting mechanism. Finally, a prototype testing is conducted to verify the lifting angle of the back plate and the smoothness during the lifting process through an angle sensor.关键词：Multi-link mechanism;Back lifting mechanism;Back pressure;Size optimization;Kinematic analysis;Finite element analysis;Prototype test
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：Aiming at the problem of small workspace in the majority of parallel robotic legs, a novel R&(2-RPR)+UPS parallel mechanical leg with an amplification mechanism is proposed, and its main structural parameters are optimized. Firstly, the three-dimensional models of the parallel mechanical leg and the whole quadruped robot are established by SolidWorks software. The position inverse solution of the single leg mechanism is derived, and its correctness is verified through simulations using Adams and Matlab software. Secondly, the workspace volume of the single leg is computed by Monte Carlo method and used as the optimization index. The rules between the optimization index and various structural parameters are studied separately, and the optimization variables are determined. Finally, the main structural parameters of the robotic leg are optimized by the particle swarm optimization algorithm. The results show that the optimized robotic leg's workspace volume is increased by 69.83%, and the workspace ranging in X and Y directions are increased respectively by 35.26% and 19.51%, which has improved the quadruped robot's ability of fast walking and obstacle overcoming.关键词：Parallel mechanical leg;Structural parameter optimization;Particle swarm optimization algorithm;Workspace
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：The load sharing design is a crucial technology that leverages the configuration advantages of the herringbone power split gear train. To improve the load sharing characteristics of the herringbone power split gear train, a static model that accounts for support stiffness, torsional stiffness, and gear mesh stiffness is construceted. The main factors affecting load sharing characteristics under the influence of errors and varying loads are analyzed. By using Romax software, a finite element simulation model consideres structural features like floating components, flexible elements, and herringbone gears, as well as errors and transmission system deformations, and load sharing coefficients are determined. The isolated impact of factors such as eccentricity error, synchronization angle, elastic shaft torsional stiffness, and herringbone gear symmetry error on load sharing characteristics is examined. Furthermore, utilizing the orthogonal experimental method, the interaction patterns and significance levels of these factors on load sharing characteristics are uncovered. The results show that synchronization angle and herringbone gear symmetry error significantly affect load sharing characteristics, with elastic shaft torsional stiffness being the next most influential factor, and eccentricity error having a noticeable impact. To achieve superior load sharing characteristics, it is recommended to use lower elastic shaft torsional stiffness in design, and employ parameter-matching design methods for the connection between the transmission shaft and gear keyway to reduce synchronization angles.关键词：Dual-path power split gear train;Herringbone tooth;Load sharing characteristics
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22
Design· Calculation
- 摘要：The spur gear with high contact degree used in the helicopter transmission system is lubricated and cooled by oil injection, and its temperature characteristics are related to the service life of the gear. Based on the computational fluid dynamics (CFD) idea, a numerical model for the temperature field of oil injection lubrication of spur gears with high contact degree is established. The volume of fluid (VOF) and the multiple reference frame (MRF) method are used to obtain the temperature and convective heat transfer coefficient of gear surfaces. The influence of lubricating oil parameters, working condition parameters and gear parameters on tooth surface temperature and convective heat transfer is analyzed by the control variable method. The gear temperature test is carried out on the CL-100 type gear testing machine. The results show that the trend of the gear temperature rising with the increase of load is consistent with the CFD simulation results. The temperature of the gear with high contact degree is higher than that of the gear with ordinary contact degree, and this phenomenon becomes more obvious with the increase of load.关键词：Spur gears with high contact degree;Oil injection lubrication;Temperature field;CFD
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：Polymer gears have the advantages of good self-lubrication and low production cost. Polymer gears are susceptible to pitting failure in transmission due to load, lubrication, etc. Metal-polymer gears' pairs have a longer service life than polymer-polymer gear pairs. To investigate the performance of elastohydrodynamic lubrication for metal-polymer gear pairs under lubrication condition, analysis of elastohydrodynamic lubrication is carried out for steel-polymer gear pairs under different working conditions, and the lubrication status and micro-pitting failure are determined by film thickness ratios and oil film safety factors. The results show that steel-polyoxymethylene (POM) gears' pairs can form stable lubricant film under oil lubrication, and the pressure angle, the rotational speed, the load and the viscosity can affect the lubrication state of gears. Therefore, the effects of pressure angle, rotational speed, load and lubricant viscosity need to be considered to avoid pitting failure.关键词：Elastohydrodynamic lubrication;Polymer gear;Micro-pitting
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：A spiral bevel gear system of the aero-engine is taken as the research object. A method of gear system-level traveling wave resonance characteristics analysis of bevel gears is proposed. Based on design parameters and machining parameters, a 3D model of spiral bevel gear pairs with accurate tooth surface is established. The static mechanical analysis of the spiral bevel gear system is carried out to ensure the normal contact of the gears. The pre-stressed modal analysis is conducted to obtain the modal characteristics of the gear system. Based on the traveling wave resonance theory, the traveling wave resonance of the bevel gear system is predicted. The result is compared with the experimental data to verify the accuracy and effectiveness of the method. The results show that the theoretical analysis is in good agreement with experimental results. This study provides a valuable reference method for resonance prediction of the spiral bevel gear system.关键词：Spiral bevel gear;Accurate tooth surface;Modal analysis;Traveling wave resonance
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22
Test·Analysis
- 摘要：To solve the engineering problem of power loss in wet brakes under non-braking conditions, taking into consideration the influence of the lubricating oil in the clearance of friction pairs on the drag torque of the friction pair, making use of the strong nonlinear fitting ability of the sparrow-search-algorithm-back propagation (SSA-BP) neural network, and taking the no-load operating condition of wet brakes as the input variable and the drag torque as the output variable, an approximate model of wet brakes is established. Compared with the traditional BP model, the prediction accuracy is obviously improved, which can meet the needs of practical engineering. In order to obtain the minimum drag torque, the working parameters are searched and optimized through chicken swarm optimization （CSO） intelligent algorithm, and the best working condition of the wet brake is obtained. The experimental results show that the drag torque and power loss between the friction pairs after optimization are significantly lower than those before optimization. This study provides theoretical research basis and engineering practice experience for the further optimization of wet brake structure.关键词：Wet brake;Drag torque;SSA-BP model;CSO algorithm;Approximate model
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：Based on the characteristics of high error sensitivity and large load capacity of the shoulder joint of the upper limb rehabilitation robot relative to other joints, an involute planetary reducer with small tooth number difference is applied to its shoulder joint drive in this study. Considering the main factors of transmission errors caused by machining and assembly errors, the analytical calculation model of transmission errors of the planetary reducer with small tooth number difference is established based on the mesh line increment method. From the perspective of statistics, Monte Carlo method is used to analyze the effects of eccentricity error and initial phase on the transmission accuracy of the shoulder joint of upper limb rehabilitation robots. Based on the analytical model of shoulder joint transmission accuracy, the output torque fluctuation caused by transmission error is analyzed and particle swarm optimization algorithm is adopted to optimize transmission accuracy under the condition of constant machining accuracy, so as to improve the output torque fluctuation caused by transmission error of the shoulder joint of the upper limb rehabilitation robot to avoid the secondary injury of the patients.关键词：Upper limb rehabilitation robot;Shoulder joint reducer;Transmission accuracy;Optimization
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：The increase of parts in the assembly leads to the complexity of the assembly process and technology, the planning of the assembly sequence has become more rigorous, and the computer-aided assembly sequence planning has become an important direction of virtual assembly. In this study, taking vertical planetary gearbox as an example, assembly coupling undirected relation diagram is used to determine the assembly coupling relation, and the assembly association matrix is transformed into mathematical information. Then through the in-depth study of ant colony algorithm, the assembly path is planned. The results show that the assembly time of the vertical planetary gearbox is reduced by 20%, and human resources are saved by 1/3.关键词：Assembly sequence planning;Vertical planetary gearbox;Parallel assembly;Ant colony algorithm
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：The electrification of heavy duty commercial vehicles is one of the critical path for solving its problems of high energy consumption and high pollutant emission. And the configuration scheme design and parameter matching of electric drive systems are the foundation of heavy duty commercial vehicle electrification. The dual driving axles of heavy duty trucks are taken as the research object. Then, the electric drive configuration scheme and parameter matching of the dual electric driving axles are studied. Several kinds of electrical drive configurations are analyzed and compared. Then, the dual electrical drive axles are determined. Specifically, the number of driving motors and the number of transmission gears are determined. Based on the configuration scheme, the main components structural performance parameters are calculated according to the functional and performance requirements of the vehicle. These parameters include power, speed and torque of the driving motors, the speed ratio of the transmission device, and the terminal voltage and capacity of the power battery. Then, the dynamic model of the electric heavy commercial vehicle is developed based on the designed configuration scheme and the matched components parameters. The dynamic and economy performance of this vehicle are simulated using the model. The simulation results show that the maximum speed can reach 100 km/h, the maximum grade-ability can reach 30%, and the driving range exceeds 300 km. It is illustrated that the configuration and parameters of the electric dual driving axles can meet the heavy commercial vehicle performance requirements. In the end, the relevant research can provide theoretical and technical support for the electrification of heavy commercial vehicles.关键词：Heavy duty commercial vehicle;Electrical drive axle;Configuration design;Parameter matching
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22
Development·Application
- 摘要：The main responsibilities, standardization fields and current centralized standards of standardization technical committees in the domestic and foreign gear industry are summarized. The corresponding relationship between the number of standards in different technical fields and the year of publication is statistically analyzed. The standardization technical elements of standards at different levels in China are also analyzed, and the development trend of gears related technologies is analyzed. In response to several new changes in China's standardization work in the new era, new requirements for the standardization work in the gear industry are proposed from both opportunities and challenges.关键词：Field of gears;Standard statistics;Technical element;Standardization
- 3
- |
- 0
- |
- 0
发布时间：2024-07-22 - 摘要：Patients' quality of life is greatly affected by shoulder joint injuries resulting from stroke, occupational hazards, or accidents. The development and application of shoulder joint rehabilitation equipment can effectively improve the mobility of patients' upper limbs. This study briefly describes the anatomical structure of the shoulder joint and the kinematics of upper limb movement. Rehabilitation equipment is categorized into three types: shoulder joint rehabilitation devices, end-effector-oriented, and exoskeleton-oriented rehabilitation robots. The characteristics of shoulder joint rehabilitation equipment are detailed, including the structural design, actuation methods, and human-machine interactions, and these aspects are summarized and compared. Problems and key technologies associated with current shoulder joint rehabilitation equipment are analyzed, and its future developmental directions are discussed. The study provides references and offers insights for future related research work.关键词：Shoulder joint rehabilitation equipment;Rehabilitation device;Upper limb rehabilitation robot;Key technology
- 2
- |
- 0
- |
- 0
发布时间：2024-07-22
Review
- Technical support is provided by Beijing Founder electronics co., LTD 豫ICP备05013835号-5
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0