摘要：
装载机动力传动系统的设计借鉴了汽车动力传动系统的设计理念,而循环工况是汽车动力传动系统参数设计的重要参考依据.由于目前还没有装载机的循环工况,所以在设计阶段也无法利用循环工况考察其燃油经济性和动力性.根据装载机发动机功率分流情况,装载机循环工况应由装载机典型工况液压系统载荷时间历程、铲斗工作阻力时间历程、工作速度时间历程构成.针对这一情况,以ZL50装载机为例,构建了试验方案,分别试验测试了装载机液压泵消耗发动机转矩的时域波形数据,前、后传动轴消耗发动机转矩的时域波形数据,以及前传动轴转速时域波形数据.对液压系统试验获取的数据进行分段、合并、去除异常值等预处理后,采用加权求和方法,制取了典型工况液压系统载荷时间历程.应用同样的数据处理方法,分别获得典型工况工作速度时间历程,以及典型工况传动系统载荷时间历程.根据典型工况传动系统载荷时间历程,应用装载机工作过程中力的平衡方程方程,求得典型工况铲斗工作阻力时间历程.典型工况液压系统载荷时间历程、铲斗工作阻力时间历程、工作速度时间历程组合在一起,共同构成装载机循环工况.应用该循环工况,虚拟试验ZL50装载机燃油经济性,与实车试验结果的一致性较好,构建的循环工况可行.装载机循环工况可为虚拟试验装载机动力性、燃油经济性提供加载数据,具有重要的工程实践意义.%The design of loader's driveline draws on the design concept of automobile's, while driving cycle is the important reference for designing the parameters of automobile's driveline. Because there is no driving cycle for loader, it is impossible to investigate the fuel economy and power performance by using it for loader in design stage. According to the power diffluence of loader engine, the loader cycle condition should consist of time course of loading, bucket's working resistance and working speed under loader's typical working condition. In view of this situation, taking ZL50 type loader as an example, this paper builds the test scheme, and the time domain waveform data of the engine torque consumed by hydraulic pump, steering pump, variable speed pump, front transmission shaft, and rear drive shaft, as well as the time domain waveform data of revolving speed of front transmission shaft are obtained. The steps of constructing the driving cycle of loader under typical working conditions are as follows: (1) On the basis of tested gear signal and hydraulic pump pressure signal, the working cycle of loader is divided into 4 work periods in terms of signal change characteristics: no-loading driving, shoveling, going forward with heavy load and unloading. Meanwhile the no-loading driving includes going forward without load and retreat without load. The all tested channel signal is shown by Vib array of data collection system, the initial time of all work periods is recorded conveniently by channel signal, and the beginning time of signal is defined according to the work period in order to determine the time period of signal segmentation. The data section of the signal can be realized directly by the nsoft. Specifically after all tested loader signals are divided according to working period, all the loading signals of the same working period are merged in each test, and lastly the acquired signals of the same working period of all tests are merged and set zero. (2) The loading time course of engine torque consumed by working pump is acquired correspondingly when shoveling the 5 kinds of material by using the nsoft, and then the loading time course of engine torque consumed by working pump is obtained by means of weighted summation method. The loading time course contains 5 working steps, which include going forward without load, shoveling, retreat with heavy load, going forward with heavy load, unloading and retreat without load. (3) According to the above method, the loading time course of engine torque consumed by variable speed pump and steering pump is got. (4) The loading time course of hydraulic system under typical working condition is acquired by adding up the above 3 time courses of the torque. (5) In a similar way, the working speed time course and loading time course of loader transmission system under typical working condition are obtained. The traditional system is mainly used to overcome the bucket work resistance, climbing resistance, rolling resistance, air resistance and acceleration resistance. (6) Based on the changes of the tested working pump pressure and gear signal, the 5 steps of a working cycle can be determined, which include going forward without load, shoveling, retreat with heavy load, going forward with heavy load, unloading and retreat without load. During the loading time course of transmission system under typical working condition, the added torque of shoveling period is consumed by the bucket's working resistance. The time course of bucket's working resistance under the typical working condition can be acquired by converting the difference value of torque. Using the same data processing method, the working speed time of typical working conditions and the load time of the typical driving system are obtained respectively. According to the load time of the transmission system under typical working conditions, the working force time of a typical working bucket is obtained by applying the balance equation of force in the working process of the loaders. In typical working conditions, hydraulic system load time, bucket working resistance time and working speed time are combined together to form loader cycle condition. Based on the cycle working condition, the fuel economy of the virtual test ZL50 loader is in good agreement with the real vehicle test result with relative error of 5.0％, which indicates that the cycle condition built in this paper can be trusted. The driving cycle of loader can supply loading data for virtual tests of loader's power performance and fuel economy, as well as provide reference for matching the power transmission system and optimizing the economic performance.
