【作者】 赵小波；

【导师】 姬长英；

【作者基本信息】 南京农业大学 ， 农业机械化工程， 2009， 博士

【摘要】 制动性是车辆主动安全性能中最主要的性能之一,良好的制动性能是车辆安全行驶的重要保障。随着车辆动力技术的提高和道路条件的改善,车辆载重量和行驶速度的增加使得主制动系统制动负荷过大的问题日渐突出,车辆的安全性能越来越受到人们的普遍重视。解决制动负荷过大等问题切实可行的方法是加装辅助制动装置。永磁式涡流缓速器是独立于车辆主制动系统和驻车制动系统以外的一种新型的节能、环保行车辅助制动装置。它通过电磁感应原理,利用永磁场产生强大的非接触式制动效能,及时对车辆制动负荷分流,不仅增强了行车安全性,而且延长了主制动器的使用寿命,是将来车辆辅助制动装置发展的新方向。目前,国内的相关研究仍处于起步阶段,制动系统生产企业缺乏具有自主知识产权的永磁式涡流缓速器产品。因此,开展永磁式涡流缓速器关键技术的研究,不仅具有重要的学术价值,而且对提高国内车辆主动安全性能以及推动我国车辆辅助制动装置行业的科技进步都具有重要意义。在此背景下,结合当前国内外在永磁式涡流缓速器方面的研究现状,采用理论分析、有限元求解和试验测试相结合的方法对永磁式涡流缓速器的制动力矩、电磁场和制动性能展开了系统的研究工作。主要研究内容和取得的结论包括：1、永磁式涡流缓速器涡流与制动力矩计算方法的研究。在合理简化永磁式涡流缓速器物理模型的基础上,以电磁场理论为理论指导,考虑涡流透入深度,推导出永磁式涡流缓速器转子鼓上涡流密度和有效电流数学表达式,在此基础上,将永磁体等效为磁动势,把涡流去磁效应折算到永磁体上,利用等效磁路方法获取了气隙磁密的计算公式,进而由涡流损耗原理推导出制动力矩的计算公式。为深入揭示出永磁式涡流缓速器制动机理,将永磁体等效为磁化面电流,从麦克斯韦方程出发,应用Rogowski方法,重点分析了气隙磁场和涡流密度的分布,推导出了永磁式涡流缓速器制动力矩计算公式。为验证制动力矩理论计算公式的有效性,在缓速器试验台上进行了试验研究。结果表明：制动力矩理论计算值与试验结果的误差小于10%，在可接受范围内,等效磁路法适用于缓速器工程设计,Rogowski法适用于永磁涡流制动机理理论研究。2、永磁式涡流缓速器磁场有限元分析与漏磁研究。忽略转子鼓转动效应和涡流去磁效应,应用有限元理论和有限元软件ANSYS建立永磁式涡流缓速器有限元模型,对准制动状态时转子鼓、永磁体和磁铁支架等部件上的静磁场分布进行数值模拟,分析了准制动状态时气隙磁密随磁性材料特性、气隙宽度、永磁体尺寸、转子鼓尺寸以及磁铁支架厚度变化的关系,试验验证了气隙磁密有限元计算结果。运用有限元法研究了非制动状态时气隙宽度、永磁体尺寸和磁极数对漏磁系数的影响规律,并对一种新型永磁式涡流缓速器漏磁进行了探讨。研究结果表明：有限元计算结果与试验值基本吻合,采用有限元方法研究永磁式涡流缓速器电磁场特性是可行的。仿真计算结果为该类缓速器的结构参数优化选择和进一步的性能分析奠定了基础。3、永磁式涡流缓速器的关键技术研究。对永磁式涡流缓速器的永磁材料、软磁材料、永磁体磁化方式的选择,磁极数和磁极片厚度的确定进行了系统的分析和探讨。针对制动状态时要对感应涡流进行直接测量非常困难,提出了永磁式涡流缓速器制动状态下感应涡流密度的软测量技术。根据仿真分析的结果得出了永磁式涡流缓速器制动状态下感应涡流随转子鼓转速、气隙宽度的变化规律,在此基础上建立了永磁式涡流缓速器制动状态下涡流密度的软测量模型。研究结果表明：基于RBF神经网络的涡流的软测量模型具有很高的测量精度,可以在实际工程计算研究中发挥有效作用。4、永磁式涡流缓速器制动性能影响因素敏感性研究。为研究永磁式涡流缓速器制动性能与结构参数的关系,以制动力矩作为评价缓速器制动性能的指标,采用均匀设计和逐步回归分析方法建立了制动力矩与五个结构参数(转子鼓内半径、永磁体周向长度、气隙宽度、转子鼓轴向宽度以及永磁体高度)的回归方程,分析了上述5个结构参数对永磁式涡流缓速器制动力矩影响的敏感性,掌握了结构参数变化对制动性能影响的规律。基于敏感性分析结果,以增大制动力矩为目标,采用全排列法对永磁式涡流缓速器结构参数优化。研究结果表明：永磁体高度对永磁式涡流缓速器制动性能有显著影响,其次为永磁体周向长度,第三为气隙宽度,第四为转子鼓轴向宽度,而转子鼓内半径对制动性能的影响不敏感；结构参数优化效果显著。研究结论可为永磁式涡流缓速器设计过程中各主要结构参数的选择和优化提供参考依据。5、装用永磁式涡流缓速器车辆制动性能研究。建立了使用永磁式涡流缓速器制动时的汽车动力学方程,基于ECE法规实例仿真分析了永磁式涡流缓速器与主制动器复合制动对车辆制动稳定性的影响,采用道路试验和理论分析相结合的方法,从平路减速距离和坡道稳定持续下坡车速与坡度关系两个方面分别考察了使用永磁式涡流缓速器单独制动以及其与排气制动联合制动的制动能力。研究结果表明：只要永磁式涡流缓速器与整车匹配得当,复合制动对原车的制动稳定性没有太大影响；车辆装用永磁式涡流缓速器能缩短减速距离,在坡度不大于5%的坡道上能满足车辆持续制动下坡的要求；制动联合制动能进一步提高车辆的制动能力。更多还原

【Abstract】 The braking ablity is one of the major performances for vehicle’s active safety, and good braking will guarantee safe working for vehicles. Along with the improvements of vehicle dynamical technology and road conditions, which lead to the increase of automotive loading capacity and driving speed, the importance of vehicle’s safety performance is getting more and more emphasized. A practical solution to problems resulting from large braking load of vehicles is the auxiliary braking device.Permanent magnet type eddy current retarder is a novel auxiliary braking device apart form the vehicle’s own braking and parking brake system, featuring beneficial to energy saving and environment protection. Based on the principle of electromagnetic interaction, the device redistributes the braking load in time by making use of the strong non-contact braking ability generated by the permanent magnetic field. With this kind of the device, not only is the safety performance enhanced, but also the service life of the main braking system is greatly prolonged, indicating a new direction for auxiliary braking device development. At present, the domestic research on permanent magnet type eddy current retarder is just in its initial stage. Domestic auxiliary braking system manufacturing enterprises are short of their own intellectual properties of permanent magnet type eddy current retarder. Under the background mentioned above, research on permanent magnet type eddy current retarder will not only have academic values, but also be important to improve the vehicle’s main braking performance, and lead to scientific and technological progress of vehicle’s auxiliary braking system industry of China. Based on the present study and technology of permanent magnet type eddy current retarder at home and abroad, the author made systematic study on the electromagnetic field, braking toque and braking performance of the permanent magnet type eddy current retarder with theoretical analysis, finite element analysis and testing approaches. The major research work and results are summarized as followed: 1. The computation of eddy current and braking torque for permanent magnet type eddy current retarder. Based on the reasonable simplification of the physical model and the consideration of penetration depth, the author derived the formulations to calculating eddy current density and effective current. Furthermore, through computing the equivalent magnetic potential, adding the demagnetization effect to the permanent-magnet and applying the air-gas magnetic flux density expression obtained with method of equivalent magnetic circuit, the author derived the braking torque formulation from the eddy current loss principle. To find the braking principle of the retarder, the equivalent magnetic surface current was calculated. Based on the Maxwell equation and the Rogowski method, the distribution pattern of air gas magnetic field and eddy current density were analyzed, and braking torque formulation for calculating permanent magnet type eddy current retarder was derived. To prove the effectiveness of braking torque theory, experiments were carried out on the test-bed. The results showed that the error between theoretical and experimental results was less than 10%, which is acceptable. It is concluded that the equivalent-magnetic-circuit method could be suitable for the engineering design and the Rogowski method effective for the braking principle theoretical research.2. The finite element analysis of magnetic field and magnetic leakage research. Under the condition of ignoring the rotation effect and demagnetization effect, and with the help of finite element analysis software ANSYS, the author completed the following research:building the finite element model for permanent magnet type eddy current retarder, simulating the static magnetic field distribution of the quasi-braking state, analyzing the relationships among the air-gas magnetic density, various magnetic material characteristics, size of rotor and permanent magnet, air-gas width and thickness of the components. The experimental results showed to be consistent to the theoretical results. Based on the finite element method, the influence of air-gas width, permanent magnet size and magnetic polar number on the leakage coefficient was analyzed, and the magnetic leakage for a novel permanent magnet type eddy current retarder was discussed. The finite element analysis results showed to be consistent to the experimental results. It is concluded that it could be feasible to apply finite element analysis to study the magnetic field characteristics. The simulation result may provide the foundation to the further performance analysis and the optimal parameters selection.3. The research of key techniques for permanent magnet type eddy current retarder. The techniques for selection of material, size, magnetization methods and polar number and thickness were analyzed. Since it is difficult to directly measure the induction current of braking states, the author proposed a Soft measurement method. Behavior of induction current with the variation of rotating speed and air-gap width was obtained based on the simulation analysis. The soft-measuring model of eddy current density for braking state then was built. The results show clearly that RBF neural network based soft-sensing model has high measurement precision, and can play efficiency effect in practice engineering calculation and study.4. The sensitivity research of influential factors of braking performance. In order to learn the relationship between the braking performance and structural parameters, the regression equation with braking torque as the function of five structural parameters (inner radius of rotor, circumferential length of permanent magnet, air-gap width, axial width of rotor, height of permanent magnet) was constructed based on the uniform design and regression analysis. The influential sensitivity of the above five structural parameters on the braking performance was analyzed and their relationships were obtained. Based on the results from sensitivity analysis, the structural parameters of retarder were optimized by the full-arrangement method, aimed at increasing the braking torque. The results showed that the height of permanent magnet was the most significant factor to impact the braking performance and the other factors were inner radius of rotor, air-gap width and axial width of rotor in a descending order. The inner radius of rotor had no significant influence on the braking performance. Structural parameters optimization showed remarkable effect. The research results may be helpful to the selection and optimization of the structural parameters.5. The research of the braking performance for vehicles equipped with permanent magnet type eddy current retarder. The researches in this part include:constructing the dynamics equation for vehicles equipped with permanent magnet type eddy current retarder, analyzing the influence of united braking system witch includes the permanent magnet type eddy current retarder and the vehicle’s own braking device on the braking stability based on the ECE law simulation, and comparing the braking performance of single retarder to that of the retarder combined with exhaust braking system in terms of the deceleration distance on flat road and the relationship between speed and slope on slope road, the researching approach being field test combined with theoretical analysis. The results showed that united braking had no significant influence on braking stability if the retarder matches well to the whole vehicle. The equipment of the permanent magnet type eddy current retarder could reduce the deceleration distance and meet the continuous braking requirement in the case of slope less than 5%. The united braking system could further improve the braking capability of vehicles.更多还原