The trapped oil phenomenon of gear pump directly affects the working characteristics of gear pump,although scholars at home and abroad have done a lot of theoretical research and obtained a lot of research results,but the trapped oil area parameter measurement is still difficult to solve the prob-lem.A small side-gap gear pump model was established,the oil trapping characteristics of the external gear pump were simulated by PumpLinx software,the tracking observation point setting method was studied,and the results were compared with those in the existing literature,which verified the reliability of the proposed method and provided references for further design and development of high-perform-ance external gear pumps.

根据一种移动式排水泵站的水泵设计工作点及工作环境,确定了水泵结构的总体方案,并对水泵的关键结构参数进行了计算与选择确定.基于CFturbo软件对水泵过流几何参数进行了设计,并利用CFD数值计算软件PumpLinx与CFturbo软件无缝连接功能构建了水泵的仿真模型,利用三维造型软件Creo实现叶轮的三维造型.对水泵的内部流场及工作特性进行仿真分析,并进行了装车试验,试验与理论分析结果吻合较好,验证了设计的合理性.同时,分析了导叶和导流罩对水泵内部流场的影响,当无导叶时内部流速与轴向有很大的夹角,使静压水头减小,动压水头增大;当无导流罩时,在径向突变位置出现环流现象,增大了流场混乱程度.

为了解决目前逃生缓降器下降速度变化范围大的问题,在固定节流口液压阻式逃生缓降器的基础上,提出了一种感载式自动调速液压缓降器.对感载式自动调速液压缓降器的工作原理进行了阐述,建立了感载式自动调速液压缓降器的结构及动力参数关系表达式.对影响感载式自动调速液压缓降器下降速度的关键要素进行了分析,推导出下降速度、节流口直径以及人体重力等工作变量关系式,并通过实例对感载式自动调速液压缓降器的工作特性进行了分析.本文研究的感载式自动调速液压缓降器可以实现人体重力自动调节下降速度,使下降速度在较窄的范围内变化,提高了缓降器工作速度的稳定性,因此可以实现在国家标准规定的安全下降速度0.16～1.5 m/s范围内,在接近1.5 m/s速度的快速区域内工作,提高人员的逃生速度和缓降器的工作效率.本研究为高端液压缓降器的开发奠定理论基础.

针对现有水田打浆机水平控制系统在耕作时机械的倾斜和振动会导致耕整后的地表平整精度低、可控性差等问题,设计了以STM32为主控芯片的平地系统控制器.为了消除振动对控制效果的影响,设计了基于限幅递推平均滤波的PID算法并进行试验研究,试验结果证明,限幅递推平均滤波对倾角数据处理有效地抑制了系统干扰和机具振动干扰;再此之后并进行了田间试验以证明本设计的水平控制系统明显比现有的平地系统耕整后的田间土壤起伏波动小,以期达到较好的控制效果.

This paper firstly presents a novel 4-SPS/S (active chain/passive chain) parallel manipulator (PPM) driven by four pneumatic artificial muscles (PAMs). SPS denotes a spherical pair–prismatic pair–spherical pair chain and S denotes a spherical pair chain. The PPM proposed can be utilized as shoulder, wrist, waist, hip and ankle simulators or ankle rehabilitation robot. And we present a comprehensive analysis on the PPM proposed, including degrees of freedom (DOF), position, kinematic, Jacobian, singularity, decoupling and workspace analysis. In order to decrease the influence of the maximum angle of spherical pairs in four active chains on the workspace, a novel connector for PAM is proposed. The structure of the PPM is explicitly described, and DOF of the PPM are analyzed based on constraint screw theory. The posture of the moving platform (MP) of the PPM is obtained though Z–Y–X (α–β–γ) type Euler angles and the inverse position solution is obtained. When the MP moves toward any a single Euler angle direction, the closed-form direct position solution is presented by geometric analysis. A back propagation (BP) neural network model for the whole direct position solution is established. Two methods for the Jacobian matrix, one velocity composition, one differentiation, are addressed, and the acceleration inversion is obtained. Based on the Jacobian matrix, the singularity and kinematic decoupling of the PPM are both analyzed. The geometric model of expanded PAM is introduced, and the change of diameters of four PAMs in active chains is taken into consideration when chains of the PPM interfere. Based on length ranges of four active chains, the maximum angle of spherical pairs and possible interferences between chains of the PPM, the configuration workspace is presented. Finally, the characteristic of the workspace and the influence of the maximum angle of spherical pairs in active chains on the configuration workspace are both analyzed.

随着自动控制技术的发展,农业自动化程度越来越高,水田地面平整机的控制系统亦多样化发展.打浆机作为平地方式的一种,采用先打浆再通过平地装置将泥浆抹平的方式平整水田地面,以其成本低,效率高的特点被广泛使用.目前,国内的平地机械有传统平地和激光平地2种.传统的平地机具采用仿形平地原理,平整精度主要靠平地工作人员目测确定,难以达到农艺要求.光平地是利用固定的激光器提供高度基准,在移动平台有一套高度控制系统和水平控制系统,固定的基准激光和高度控制系统保证了在平地机移动过程中刮板高度的整体统一,消除由于机器振动以及地面不平对平地装置高度造成的影响,整套技术已经颇为成熟.但激光平地机一般适用于旱地平整,且装置庞大,结构复杂;又由于激光平地系统的配套设备多,成本高,且工作时所需的功率大,难以在我国推广使用.

静液压传动装置(HST)由定量马达、齿轮油泵、双向变量泵和控制阀组成,具有空间小,结构紧凑,布置比较方便等优点,大面积应用于工程机械、收割机和拖拉机等机械中.HST装置具有对外载荷的自动调节性,实现无级调速,而且可以实现扭矩连续控制.美中不足,在负载波动剧烈或工作环境过于复杂时,发动机的有效功率不能得以充分发挥,此时发动机和HST的匹配性较差.拟采用适当的调控装置与液压传动相配合,从而达到使发动机工作在最佳经济性区域和最佳动力性区域,达到很好适应外界负荷的复杂的变化目的,使工作状况达到最佳.

以4根气动人工肌肉构成的肌肉群驱动,采用加约束从动支链的方法构建了4-SPS/S并联机构;以Z-Y-X型欧拉角表示了动平台的位姿,给出了机构位置逆解的显性式;通过刚体绕定点运动的动力学方程建立了机构的动力学方程和机构的运动学影响系数矩阵,结合气动人工肌肉的内腔充气压力-伸缩力-收缩比三者的非线性关系,建立了机构动平台位姿控制系统的数学模型,并应用Simulink进行了仿真。仿真结果表明,通过输入一组可行控制电压来控制气动人工肌肉的内腔充气压力,可实现动平台的三自由度转动,而且系统运动平稳。

According to the configuration evolution method, a parallel mechanism with three rotational degrees of freedom, which is driven by group of four pneumatic artificial muscles, was designed by removing two SPS branches of Stewart mechanism and adding constraint branch to constrain the three translational degrees of freedom of the moving platform. A parallel mechanism experimental table was established. The measurement device, which is constructed by three displacement sensors, is built. The pose of the moving platform obtained by the measurement subsystem is compared with the pose from theory. Therefore, the closed-loop control was obtained.

The 4-SP xyz S/S xyz parallel bionic joint, which is driven by group of four pneumatic artificial muscles, was built by adding constraint branch. The dominant equation of the inverse kinematics solution was obtained. To solve the direct kinematics problem, a BP neural network is established by considering some special outputs (i.e. length of the driving branch) of the inverse kinematics solution as the BP neural network's inputs and the corresponding inputs as the BP neural network's outputs. And the constraint condition of solving the configuration space of 4-SP xyz S/S xyz parallel mechanism was built. The configuration space was analyzed in theory by comparing the two configuration spaces obtained by the BP neural network and the inverse kinematics solution.

The human wrist has three rotational DOFs. Elbow muscle group work together to drive the wrist joint. According to the above characteristics of human wrist, parallel mechanism with three rotational DOFs of the imitation of human wrist is built. Traditional method for calculating DOF based on arithmetic is not that accurate. The method for analysis of DOF based on theory of constraint screw is explained. According to theory of constraint screw, the parallel mechanism built was analyzed. All the kinematic pairs in the mechanism will be expressed with screws so that the common constraints and the over constraints will be obtained. Through analysis above, the DOFs of the mechanism can be calculated and which a few degrees of freedom of the mechanism will be known. The new method avoids the disadvantages of the traditional method.

The human wrist has three rotational DOFs. Elbow muscle group work together to drive the wrist joint. According to the above characteristics of human wrist, parallel mechanism with three rotational DOFs of the imitation of human wrist is built. Traditional method for calculating DOF based on arithmetic is not that accurate. The method for analysis of DOF based on theory of constraint screw is explained. According to theory of constraint screw, the parallel mechanism built was analyzed. All the kinematic pairs in the mechanism will be expressed with screws so that the common constraints and the over constraints will be obtained. Through analysis above, the DOFs of the mechanism can be calculated and which a few degrees of freedom of the mechanism will be known. The new method avoids the disadvantages of the traditional method.

高等教育趋于大众化后,人们更加关注的是高校的人才培养问题。高校之间的竞争取决于学生综合水平,而学生综合水平很大程度上与学生的创新能力密切相关。只有具有一定的创新能力,不断提出更有益于生活与发展的创新思维,学生才能更好地完善个人的综合能力,提高个人的综合素质。学校将培养学生创新能力提上日程,并相应的颁布措施与相关政策,创立并不断完善适应创新能力培养的新的教育体系。本文在探讨高校培养创新能力方式的基础上,浅析高校学生创新能力下教育体系的创立。

介绍了HZY-18新型环保全自动液压制砖机的结构组成、工作原理和性能指标;介绍了该机产品尾矿砂混凝土多孔砖的主要性能指标和特点,通过分析可以看出该产品与传统红砖比较的优势和市场潜力.

课程设计是教学过程中的一个重要的实践性教学环节,通过课程设计,使学生能够将课本上的理论知识和实际应用较好地结合起来,运用所学的理论知识解决工程中所遇到的实际问题。本文从液压传动课程设计的目的、内容、步骤及现状等几个方面对课程设计进行了综合论述,并阐述了课程设计过程中存在的问题与改革尝试,并对改革后的设计效果进行了评价,为液压传动精品课实践教学环节建设奠定了基础。

Based on the study of the mechanics features of pneumatic artificial muscle including the nonlinearities in material, geometry, and with the method of nonlinear finite element analysis, the three-dimensional finite element model of a pneumatic artificial muscle was established. The analytical results were confirmed by the experiment with the use of a pneumatic artificial muscle test bench.

The article introduces TRIZ theory to the value optimization,after confirms object of optimization by means of value analysis of engineering goods,utilizes method of TRIZ to transform practical problem into problem of TRIZ and increases the value of optimizing object,puts forward innovating program for practical problem of the value optimization,to achieve purpose of preferably accomplishing the product value optimization.

The pneumatic artificial muscle contraction range is directly determined by the extremum values of braid angle.In theory,the extremum values of braid angles are θmin=0° and θmax=54.73°,respectively.However,the fibre which constitute the pneumatic artificial muscle has geometric shape,so the actual extremum value of braid angle are different from the theory extremum value.The formula of the actual braid angle extremum value was deduced.Through discussion,the method to determine the braid angle extremum value was obtained.

Pneumatic artificial muscle (PAM) is a new pneumatic actuator. A lot of work have been completed about the principle, theoretical, experimental modeling and applications of pneumatic artificial muscle. Researchers have found that PAMs exhibit non-linear characteristic. Base on the published literatures, non-linear characteristic related to elasticity, friction between rubber and braid and the constraint ring. The former two aspects have been mainly studied in the published papers. However, study on the influence of constrains on the end of pneumatic artificial muscle is still rare. This study establishes the PAM static characteristic experimental system, and the PAM characteristics about multiple constraints are tested. Through the analysis of experimental results, the influence is obtained which constraints the work for pneumatic artificial muscle working characteristics.

The trapping phenomenon stems from the principle of gear pumps, and it affects directly the performance and life of gear pump. Reducing pressure in trapping area is an important aspect to improve working performance of gear pump, and how to test the pressure of trapping area is one of the most important problems. According to such requirements, an experimental system has been designed, and then relevant experiments are conducted on the designed experimental system. The experimental results indicate that the system can fulfill the requirements commendably.