Aiming at the problems in the design of traditional involute internal gear, such as the limitation of teeth number, the inflexibility of the profile shift coefficient and the low contact ratio, a method of internal gear with high contact ratio (HCR) based on predefined circular arc meshing line is provided. In order to realize the HCR, the circular arc connecting the intersection point of the inner gear and the outer gear tooth tip circle to the pitch point is used as the meshing line. According to the principle of gear meshing theory, firstly, an equation expression for the conjugate tooth profile curve that satisfies the circular arc meshing line is established, and the dedendum profile curve conjugated with the addendum profile curve is constructed. Then, the dedendum profile curve of the internal gear is modified to avoid simultaneous contact between two points. Finally, the tooth dedendum profiles of the internal and external meshing gears were designed. Compared with traditional involute gears, gears with HCR have greater coincidence and therefore have greater load-bearing capacity. The finite element analysis software ABAQUS is used to simulate the HCR gear meshing process. The simulation results show that, after the modification, the problem of sudden change in meshing force is improved, and the relative sliding rate of meshing in and out is reduced from -1.176/0.593 to -0.823/0.509. The maximum power loss during the meshing process is reduced from 930w to 850w, and the meshing efficiency is increased from 99.267% to 99.333%.

A kind of cycloidal cylindrical gear is presented in this study.Unlike conventional cylindrical gears,the shape of the tooth profile of this gear in its axial direction is a cycloid.This cycloid gear has the char-acteristics of large bearing capacity,smooth transmission and no axial force in performance.It adopts the method of continuous-index processing,which greatly improves the processing efficiency.The cycloidal cylindrical gear is machined with a disc milling cutter,and the disc milling cutter is equipped with replaceable blades.The same modulus gear can be machined with only one disc cutter.By replacing the blade,different modulus gear can be machined with the same disc cutter.Firstly,based on the gear meshing theory,the mathematical model of the cy-cloidal gear was deduced,the discrete tooth surface points were generated by the self-developed calculation soft-ware,and three-dimensional models were built.Then,the geometric design of the disc cutter and the processing principle of the cycloidal gear were also introduced.Finally,a calculating table for determining processing param-eters was given.This research provides a new idea and basis for the design and machining of cylindrical gears.

The research on electric drive wheel technology is an important direction of the research on the new energy drive system in the future. With the increasing requirements of the electric drive wheel on the speed, the oil churning power loss has become a non-negligible part, even up to 50%-80% of the total power loss. The existing calculation method of churning loss mainly adopts simple empirical formula, which cannot be applied to complex planetary gear transmission. The splash lubrication of the two-stage planetary gear drive is simulated by computational fluid dynamics (CFD) software and C language user defined function (UDF), and the visualization of oil gas two-phase transient flow field is realized; by extracting the surface pressure and the viscous force, the churning loss of the sun gears, planet gears and planet carriers are obtained; the simulation and analysis of the 25 working conditions show that the churning loss varies with the immersion depth and speed; the results show that the oil churning power loss increases with the oil immersion depth and the speed, and there is no obvious inflection point. To achieve the minimum oil stirring loss, the minimum oil immersion depth should be taken on the premise of ensuring full lubrication.

This article presents a method of design, manufacturing, and measuring S-gear. S-gear is a kind of gear whose tooth profile is an S-shaped curve. The sine (cosine) gear, cycloid gear, polynomial gear, and circular arc gear are all S-gears in essence. In the S-gear transmission, the concave surface of one gear and the convex surface of the other gear contact each other. Therefore, the power transmitted by S-gear is much larger than that of the convex-convex-contact involute gear. Some scholars have studied the characteristics of S-gear, but few have explored its manufacturing. In this article, the Numerical Control (NC) machining technology of S-gear is studied in detail for its industrial application. The polynomial curve is used to construct the tooth profile of the S-gear based on the Gear Meshing Theory. The mathematical model of polynomial S-gear is established, by which involute gear can be represented as a special S-gear. The steps of generating NC codes are described. Then, the S-gear sample is processed with an NC machining center. Finally, the sample is measured with a Coordinate Measuring Machine (CMM), and the measurement results show that the accuracy of the S-gear processed by the NC machining center reaches ISO6. This research provides a feasible approach for the design, manufacturing, and measuring of S-gear.

基于平面展成原理建立双圆弧齿轮齿面数学方程,通过编写的齿轮设计软件,输出齿面的离散点,通过样条曲面构造双圆弧齿轮精确的三维模型.采用视觉测量法对齿轮实物进行了测量,通过对比实物与模型,验证了建模方法的正确性.该研究成果为双圆弧齿轮的检验评定、力学分析及动态仿真提供了准确的三维模型.

双圆弧齿轮具有承载能力大、接触强度高、跑合效果好等优点,广泛应用在冶金、矿山、化工、起重、运输等机械传动领域.但是,双圆弧齿轮常常由于测量的不准确而造成切齿深度偏差,从而影响其传动性能.基于齿轮啮合原理,在基本齿条齿廓的基础上通过展成的方法,建立了双圆弧齿轮的数学模型,实现了双圆弧齿轮的数字化精确建模.采用三坐标测量仪(CMM)技术,利用齿面被测量位置法线方向作为基本测量轨迹,实现测头的精确导向.利用DMI编程自动测量技术,通过自主编写测量程序模块,实现了双圆弧齿轮的自动测量.该测量方法可以精确测量齿轮的齿形、齿廓精度,准确地反映齿形的误差,为双圆弧齿轮的高精度、精细化加工提供高效、精准的检测手段.

A new internal gear drive with a high contact ratio (HCR) is presented in this paper. In the new gear drive, the number of teeth working at the same time has reached 7, which is usually only less than 2 in the traditional involute gear drive. The bearing capacity of the new gear is improved significantly. To obtain a high contact ratio, the addendum tooth profiles of the pinion and internal gear are deduced by a given path of contact based on gear meshing theory and the dedendum tooth profile is designed as the envelope to the family of addendum tooth profile of the mating gear. The mathematical models, including the equation of the path of contact, the equations of addendum and dedendum tooth profiles and the equation of modification, are established. An example drive in the three-dimensional (3D) model is presented. The characteristics, such as contact ratio, sliding ratio, induced curvature, and the contact and bending stress are evaluated. The results confirm that the novel internal gear drive has a higher contact ratio and lower sliding coefficient, and the contact and bending stresses are reduced in comparison with the involute gear drive. Furthermore, a prototype is produced, which illustrate the feasibility of manufacturing.

It is seen that the relative motion between the friction and separate plates causes drag torque of the disengaged wet clutch, which reduces the efficiency of the automatic transmission. A mathematical model of the drag torque was presented in this paper to study the effects of the grooves and waviness on the friction plate during the disengagement of the wet clutch. The modified Reynolds equation of the lubricant film was derived from the governing equations by considering the centrifugal effect. The finite difference method was applied to solve Reynolds equation, and the shape and size of groove and waviness on the friction plates were described by the thickness of lubricant film at each mesh point in the numerical solution. Equivalent outer radius was introduced to estimate the drag torque of the disengaged wet clutch based on Newton's internal friction theorem. The influencing factors including groove shapes, groove depth and width, waviness, lubricant viscosity, and supply flow were discussed to analyze their effects on the drag torque of the disengaged wet clutch. An experimental rig was set up to test the drag torque of the grooved wet clutch and results indicated that the theoretical drag torque had good agreement with the experimental data.

针对一种模块化液压动力换挡变速器样机,设计了动力性换挡规律.对于稳态规律不能适应车辆动态工况以及油门突变情况下易导致误换挡问题,以油门开度、油门变化率、加速度和车速为参数,设计了4参数的模糊控制方法进行修正.分析车辆在坡道工况下出现循环换挡的原因,基于递推最小二乘法设计坡道预测和坡道换挡控制方法.仿真实验表明,模糊控制方法可以有效提高整车起步动力性,消除快速给油导致的误换挡;所设计坡道换挡控制方法可以有效识别坡度并消除循环换挡.

A high contact ratio internal gear drive with arc contact path was proposed for internal gear transmission. The circular arc connecting the intersection point of addendum circles and the intersection point of pitch circles was chosen as the path of contact. The addendum tooth profiles of pinion and internal gear conjugated with each other were constructed based on the given path of contact. According to gearing theory, the dedendum tooth profile was designed as conjugate curve of the addendum tooth profile of the mating gear and modification of dedendum tooth profile to internal gear was carried out. Geometric properties analysis and loaded contact analysis of the novel internal gear were also carried out. The results show that undercutting and addendum interference do not occur for the novel internal gear. The novel internal gear drive has higher contact ratio, smaller sliding ratio, but bigger induced curvature compared with the involute internal gear drive. The stress, especially the bending stress of the novel high contact ratio internal gear drive decreases remarkably. The novel high contact ratio internal gear with tooth number of 38/53 has 7 tooth being in meshing, which confirms the high contact ratio for the novel internal gear drive.

为实现一种新式模块化变速器试验样机的自动换挡功能,设计了样机配套换挡液压系统,并对换挡过程进行仿真建模.基于刚体动力学原理对二挡模块样机进行分析,并利用MATLAB/Simulink建立包括传动系和液压缸的整体仿真模型,利用溢流调压控制,设计一套简化换挡液压系统.以输出轴扭矩变化率和输入轴最低转速作为评价指标,研究充油流量、复位弹簧预紧量等参数对该新型结构样机换挡品质的影响规律.用换挡试验验证了模型和样机换挡可信度.结果表明,充油流量决定零件运动速度和液压缸内压力上升速度,影响换挡速度和换挡制动时间,增大流量可有效消除换挡制动,但会引起冲击增加;使用较小的弹簧预紧量可以减小换挡冲击.