用变惯量飞轮实现往复压缩机速度波动的调节

提出了一种变等效转动惯量飞轮的设计方法。将微型飞轮安装在与往复压缩机曲轴保持变速比的固定轴上。通过非圆齿轮传动实现轴与曲轴之间的变速比传动，这不仅能完全消除曲轴的速度波动．而且能平衡输入扭矩的波动，减少飞轮自身的重量和转动惯量。     

A novel torsional exciter for modal vibration testing of large rotating machinery

A novel exciter for applying a dynamic torsional force to a rotating structure is presented in this paper. It has been developed at IPP in order to perform vibration tests with shaft assemblies of large flywheel generators (synchronous machines). The electromagnetic exciter (shaker) needs no fixture to the rotating shaft because the torque is applied by means of the stator winding of an electrical machine. Therefore, the exciter can most easily be applied in cases where a three-phase electrical machine (a motor or generator) is part of the shaft assembly. The oscillating power for the shaker is generated in a separate current-controlled DC circuit with an inductor acting as a buffer storage of magnetic energy. An AC component with adjustable frequency is superimposed on the inductor current in order to generate pulsating torques acting on the rotating shaft with the desired waveform and frequency. Since this torsional exciter does not require an external power source, can easily be installed (without contact to the rotating structure) and provides dynamic torsional forces which are sufficient for multi-megawatt applications, it is best suited for on-site tests of large rotating machinery.     

Stossfreie tourenkupplung für hohe arbeitsgeschwindigkeitenA shock-free,high-speed,rotating coupling

The present paper reports on the development of principles allowing a considerable improvement in the efficiency of rotating couplings. A block diagram is shown in Fig. 2. The constant angular input velocity ω₀ is transformed by a step gear into a progressive stepping motion with the intermittent angular velocity ω_A (0 ? ω_Amax ω_A), and fed to a clutch with torque transmission through a positive connection. Establishing and releasing this connection is performed through response to control signals whenever the angular velocity ω_A = 0. The control signals are generated by a synchronizing unit, a logical operation being carried out between the external coupling instructions and clock pulses identifying the angular velocity ω_A = 0. Since the angular velocity difference between the input and output of the clutch is zero during the coupling action, the driven side is moved harmonically.The three gear drive and the cycloidal step gear for generating the stepping motion, as well as an electromagnetic drive for the clutch, are represented as self-contained function units for the technical implementation of the above principles. The step gears feature a shock- and jerk-free motion transmission with near-dwell. The near-dwell and the coupling time of the clutch are coordinated such that high working speeds are obtained from the rotating coupling.Theoretical considerations about the particular function units are complemented by essential suggestions concerning design and production engineering.The test results listed refer to both the individual function units and the entire coupling. The step gears can be used successfully when step angles of 360° or 180° are desired, with stepping frequencies of up to 50 Hz and higher. The electromagnetic drive enabled coupling times of less than 2 miliseconds to be obtained. In the long-duration test, 2.6 (10)⁶ stepping cycles were attained (for Vf_S = 35 Hz with J_A = 250 gcm²) by means of the full-revolution coupling, and 4(10)⁶ stepping cycles (for f_S = 50 Hz with J_A = 250 gcm²) by means of the half-revolution coupling without disturbances having occured. The results prove the fact that an ingenious combination of mechanism engineering on the one hand and of electromechanics and electronics on the other hand can produce assemblies of high efficiency.     

用变惯量飞轮实现往复式压缩机速度波动的调节

提出一种变等效转动惯量飞轮的设计方法。将微型飞轮安装在与往复式压缩机曲轴保持变速比的固定轴上,通过非圆齿轮传动实现轴与曲轴之间的变速比传动,不仅能完全消除曲轴的速度波动,而且能平衡输入扭矩的波动,减少飞轮自身质量和转动惯量。     

非圆齿轮变等效转动惯量飞轮的设计

提出了一种变等效转动惯量飞轮的设计方法。将微型飞轮安装在与等效构件保持变速比的固定轴上,通过非圆齿轮传动实现轴与等效构件之间的变速比传动,不仅能完全消除等效构件的速度波运,而且能平衡输入扭矩的波动,大大减少飞轮自身的重量和转动惯量。     

基于解决传动系统变速器齿轮敲击的分析方法

建立一汽车传动系统6自由度动力学模型,模型中包括发动机、离合器、变速器与整车,考虑了变速器内承载齿轮副以及非承载齿轮副啮合间隙。以变速器输入轴的角加速度值为评价指标,研究模型参数变化对传动系统扭转振动的影响。利用序列二次规划法对存在非承载齿轮敲击问题的某车辆的飞轮转动惯量和离合器设计参数进行优化。根据优化结果,试制了离合器,并对新旧离合器下传动系统非承载齿轮敲齿的情况进行测试,测试了变速器处的输入轴扭转角加速度、变速器壳体处加速度以及发动机舱变速器侧声压。测试结果表明,增大飞轮侧转动惯量和离合器阻尼转矩、合理地调节离合器刚度可以衰减变速器输入轴角加速度幅值,抑制非承载齿轮副敲击现象。     

The effect of cam profile errors and system flexibility on cam mechanism outputL'effet des erreurs de profil des cames et de la flexibilite du systeme sur son fonctionnement

An investigation of the effects of machining errors in the contact surfaces of a cam mechanism together with all possible system flexibility errors is carried out by simulation. An 11 degree of freedom dynamic model of a cam follower system including its drive system was selected, and the dynamic simulation is combined with a stochastic simulation of the random nature of the machining tolerances which have a considerable effect on the actual output. Jump phenomena, the preloading of the retaining spring, variations in angular velocity, characteristics of the various motion curves, flexibility of the various components, non-roundness of cam shaft bearings, non-concentricity of the base circle and machining tolerance on both cam profile and follower are all taken into account, and an analytical method to calculate the spring constant between cam and follower considering Hertzian contact is developed.The lengthy simulation program is handled on a mini-computer by utilizing suitable numerical methods and overlay techniques resulting in a continuous simulation of the effects of all input errors in a cam-mechanism. The effects of tolerance and flexibility errors are examined separately as well as in combination.     

Comprehensive analysis of the influence of structural and dynamic parameters on the accuracy of nano-precision positioning stages

Nano-precision positioning stages are characterized by rigid-flexible coupling systems. The complex dynamic characteristics of mechanical structure of a stage, which are determined by structural and dynamic parameters, exert a serious influence on the accuracy of its motion and measurement. Systematic evaluation of such influence is essential for the design and improvement of stages. A systematic approach to modeling the dynamic accuracy of a nano-precision positioning stage is developed in this work by integrating a multi-rigid-body dynamic model of the mechanical system and measurement system models. The influence of structural and dynamic parameters, including aerostatic bearing configurations, motion plane errors, foundation vibrations, and positions of the acting points of driving forces, on dynamic accuracy is investigated by adopting the H-type configured stage as an example. The approach is programmed and integrated into a software framework that supports the dynamic design of nano-precision positioning stages. The software framework is then applied to the design of a nano-precision positioning stage used in a packaging lithography machine.     

Application of whitworth quick return mechanism for high velocity impacting pressL'application du mecanisme a retour rapide de whitworth pour une presse d'impact a grande vitesse

The Whitworth quick return mechanism has been modified and used for constructing high-velocity impacting press. The impacting press drive comprises a Whitworth quick return mechanism consisting of a crank and a drive arm together with a variable speed d.c. motor, a flywheel, bearings, etc. The end of the drive arm is attached by a connecting rod to a cycloidal cam. In single cycle operation, the cam is made to engage with an upper platen (or ram) which impacts the workpiece. The upper platen and cam are both mounted on multirod supports with linear ball bushings. A brake is provided on the flywheel for emergency purposes. The high-speed impacting presses are subject to severe dynamic forces when operating at speeds of 200 rpm and greater. Although the mechanism has been designed to withstand operation at higher frequencies, the loads transmitted to the building foundations cause unwanted vibrations and noise. This paper also examines the causes of the unbalanced forces and means to reduce the loads transmitted to the foundations of the high velocity impacting press. An analysis is presented which yields an approximate expression for the angular displacement, velocity and acceleration of the quick return mechanism. Rapid changes in acceleration and high-peak values contribute to the severity of the problem. The bearing reaction forces are determined. Different approaches of this problem have been discussed and analyzed.     

Load-sharing characteristic of multiple pinions driving in tunneling boring machine

The failure of the key parts, such as gears, in cutter head driving system of tunneling boring machine has not been properly solved under the interaction of driving motors asynchronously and wave tunneling torque load. A dynamic model of multi-gear driving system is established considering the inertia effects of driving mechanism and cutter head as well as the bending-torsional coupling. By taking into account the nonlinear coupling factors between ring gear and multiple pinions, the influence for meshing angle by bending-torsional coupling and the dynamic load-sharing characteristic of multiple pinions driving are analyzed. Load-sharing coefficients at different rotating cutter head speeds and input torques are presented. Numerical results indicate that the load-sharing coefficients can reach up to 1.2-1.3. A simulated experimental platform of the multiple pinions driving is carried out and the torque distributions under the step load in driving shaft of pinions are measured. The imbalance of torque distribution of pinions is verified and the load-sharing coefficients in each pinion can reach 1.262. The results of simulation and test are similar, which shows the correctness of theoretical model. A loop coupling control method is put forward based on current torque master slave control method. The imbalance of the multiple pinions driving in cutter head driving system of tunneling boring machine can be greatly decreased and the load-sharing coefficients can be reduced to 1.051 by using the loop coupling control method. The proposed research provides an effective solution to the imbalance of torque distribution and synchronous control method for multiple pinions driving of TBM.     

尺蠖式直线微驱动器的设计

针对普通尺蠖式直线微驱动器运动速度低和输出力小等问题,基于柔顺机构设计了一种新型尺蠖式直线微驱动器。微驱动器由箝位机构、驱动机构和输出轴组成,其运动特点是驱动机构驱动箝位机构进行往复直线运动,箝位机构带动输出轴作直线运动。箝位机构和驱动机构均采用柔性杠杆结构,保证了微驱动器所需的箝位力与驱动力,并提高了其运动速度。采用伪刚体方法建立了驱动电压与箝位力、驱动机构输入位移与输出位移之间的关系,根据功能原理建立了输入力与驱动力之间的关系并制作了样机,搭建了实验测试系统进行性能测试,测试结果表明,驱动器最大箝位力为216.43N,最大驱动力为13.5N,在驱动电压120V,频率95Hz时,达到最大速度48.91mm/s。     

Combined two-line power transmission synthesisCинтeз кoмБиниpoяaннoй дяyчпoтoчнoй cилoяoй тpaнcмиccии

The synthesis of a multistage electromechanical transmission consisting of two directly connected three-link gear differentials is proposed. The characteristic feature of the transmission is the fact that, for shifting control ranges, the effect of a structural change is used instead of a gear box. This effect is achieved by means of connecting electrical machines to the input shaft, output shaft or, finally, to the external support shaft. In this case, an expansion of the control range is achieved by means of a double change of electrical machine regimes. Continuous control and constant torque action are secured by means of shifting over at the moment when shifted links are in the zero-power regime.     

Dynamic analysis and load-sharing characteristic of multiple pinion drives in tunnel boring machine

A dynamic model of multi-gear drive in a tunnel boring machine is demonstrated in this study in which the effects of inertia on the driving mechanism and cutter head are considered. With the nonlinear coupling factors between the ring gear and multiple pinions considered, a dynamic analysis of multiple pinion drives is conducted, and their load-sharing characteristic is proposed. The load-sharing coefficients at different rotating cutter head speeds and input torques are determined and are found to reach up to 1.2–1.3. A simulated experimental platform of multiple pinion drives is performed, and subsequent torque distributions are measured under step load in the driving shaft of pinions. An imbalance in torque distribution of pinions is verified, and the load-sharing coefficients in each pinion can reach 1.262. Torque load fluctuation is regarded as system noise that can directly be coupled into the control system in the control strategy.     

变惯量高效微型飞轮的理论与综合

与传统飞轮不同的变惯量飞轮不与机器的主轴固联,这样变速运动的飞轮折算到主轴的等效惯量不是常数,其动能也不是常数。利用变惯量飞轮的动能波动来抵消原机器中惯性和载荷对机器平稳运转的不利影响,从而平稳机器主轴的角速度波动。在起到同样的平稳效果时,变惯量飞轮的惯量比传统的飞轮小许多。给出了变惯量飞轮的原理以及变惯量飞轮的二种结构型,并相应给出二个计算实例。     

Optimum elastodynamic synthesis of a cam-follower train using stochastic-geometric programmingOptimale elastodynamische synthese von kurvengetrieben mittels stochastisch geometrischer programmierung

Due to inertia and elasticity of the follower train the actual response is always different from the motion machined into the cam. The object of the designer is to reduce this error, which may be termed as flexibility error, and to prevent the separation between the cam and follower. In this paper a method is presented to determine stochastically the optimum values of the retainer spring constant and the mass of the follower train for minimum flexibility error and no separation. Signomial geometric programming is used for optimization. An example problem is included.     

MICRAS,Microcomputer interactive codes for robot analysis and simulationMICRAS: Logiciel interactif sur micro-ordinateur pour l'analyse et la simulation des robots

With the growth and acceptance of interactive computer graphics, contemporary robotic research trends are focusing on the development of robot simulation packages. This paper describes a new microcomputer interactive package for the analysis and simulation of industrial robots. The package represents an extension of the state-of-the-art developments in the technology of industrial robots. The novel features are derived from the use of the microcomputer for analysis and simulation. The package includes all aspects of the kinematic analysis of the six general geometric structures of industrial robots.MICRAS is a package of microcomputer interactive codes for robot analysis and simulation. The program WORKSPACE is used for obtaining the value and plot of the workspace of two- and three-link revolute-jointed arms. DIRKIN is a program that generates the forward solution for any robot with up to six degrees of freedom. The data input section provides the robot geometric parameters and joint angles interactively. The program REVKIN is constructed to give the inverse solution of the six major kinematic structures of robots and display all possible configurations for each robot. COJOINT is a program that implements coordinated joint motion of a robot with defined range of motion of each joint. The modules with prefix CAT constitute the program for the simulation of robot movements for a specified cartesian path of the end effector. Finally, DIRDIF is a program for the differential kinematic analysis of robots.     

The minimization of the fluctuation of input shaft speed in cam mechanismsDie minimierung der drehzahlschwankungen in der antriebswelle der kurvengetriebe

In this article, a disc cam with an oscillating flat faced follower is considered and the speed fluctuation of the input shaft driven by a three-phase a.c. motor is minimized. First, the equation of motion for the mechanism is determined, then by solving this equation for steady state motion the coefficient of speed fluctuation is calculated. The optimum dimensions that would minimize the coefficient of speed fluctuation are determined by taking into account various geometrical parameters.     

Computer optimization of trailer suspensionsOptimisation par ordinateur des suspensions de remorque

This paper presents an optimization procedure which has been developed to select appropriate suspension design parameters for a simple two wheel trailer. A modern approach to the optimization problem has been used applying non-linear programming to the constrained search for the minimum of an objective function. The acceleration response to roadway input of selected points on the load of the trailer has been designated for minimization. This acceleration has an important significance to the trailer design because of its effect on the stable and smooth ride of the trailer. Two computational procedures have been used and the results compared. The first approach involves the linear superposition of responses to a series of discrete sinusoidal inputs while the second applies more contemporary random vibration theory using power spectral density curves to simulate the actual road surfaces. The results of the optimization procedure are then compared with the response characteristics of the original trailer design and demonstrate that a substantial improvement has been made.     

Toggle mechanisms: Dynamics and energy dissipationDynamik,reibung und energieverluste beim kniehebelgetriebe

The dynamic performance of a toggle mechanism is investigated. Particular attention is given to (i) the collapse of the toggle in the presence of Coulomb friction, and (ii) the effect of a varying periodic force on the mechanism with damped elastic coupling. For case (i), a method utilizing both equations of motion and the kinetostatic analysis is outlined to solve for frictional torque and it is concluded that the performance of the mechanism under the influence of Coulomb friction depends highly upon the input energy to the system. It is shown that there is an optimum impulse speed almost equal to a defined version of the quasi-natural frequency of the system which can minimize the energy loss. For case (ii), a dimensionless grouping in terms of the forcing amplitude and the parameters of the system is found for determining the stability of the system. An approximate analytical solution for the time history of motion under the assumed condition is obtained.     

Computer-aided design of a leg for an energy efficient walking machineLa conception assitee par ordinateur d'une jambe pour une machine marchante energetiquement efficace

Vehicles with legs instead of wheels have been studied for a number of years. One of the reasons for interest in such vehicles is that animals use only 10% as much energy as wheeled or tracked vehicles when traveling over rough terrain. The leg geometry is the most crucial aspect of the design since it strongly influences the efficiency of the vehicle. The legs should be simple in structure, and when the motion of the body is on a horizontal straight line, only one actuator per leg should be active in order to have good energy efficiency. The design of an energy efficient walking machine leg is described in this paper. In the design procedure, the motion of the leg is considered first, and a very simple leg developed from a 4-bar linkage and designed using a computer-aided interactive program is described. Second, the forces on this leg during a typical motion cycle are discussed. The leg is driven by a primary actuator for straight line walking and two secondary actuators which vary working height and change direction. A prototype of the leg is being built in The Department of Mechanical Engineering at The Ohio State University.