基于典型工况的装载机发动机与液力变矩器匹配

针对目前发动机与液力变矩器常用匹配方案中发动机净转矩获取方法的不足,为实现发动机与液力变矩器更科学、合理的匹配,构建了装载机液压测试系统,对传感器性能进行了标定。在典型工况下开展了实机试验,应用nSoft软件对测试数据进行处理,得到液压系统实际消耗的发动机转矩为288.76 N·m,进而提出了一种基于典型工况的发动机与液力变矩器匹配方案。根据试验用装载机发动机与液力变矩器原始特性数据,应用数据拟合方法,得到了发动机与变矩器的共同输入与输出特性。采用积分平均方法求取了涡轮工作高效区涡轮轴平均输出功率和发动机平均油耗率。在变矩器高效区,试验功率匹配方案的涡轮轴平均输出功率分别比原匹配方案、部分功率匹配方案高17.02%和42.59%,试验功率匹配方案的发动机平均油耗率分别比原匹配方案、部分功率匹配方案低3.80%和8.72%。结果表明文中提出的匹配方案优于目前常用的匹配方案。该研究为液力变矩器的优化设计、发动机与液力变矩器合理匹配提供了参考。

Power matching on loader engine and hydraulic torque converter based on typical operating conditions

Abstract: In order to avoid the deficiencies of obtaining net engine torque in several common methods, and realize more scientific and reasonable matching between engine and hydraulic torque converter, a hydraulic test system for wheel loader was established, the performances of three sensors were calibrated, and a quantitative relationship was obtained between outlet pressure of hydraulic pump and engine torque consumed by the pump. Some actual tests were performed under typical operating conditions, and the test data were processed by a series of procedures, including segmentation, mergence, filtration, elimination of abnormal value and weighted average calculation with nSoft software, and the engine torque actually consumed by loader hydraulic system was obtained when comprehensively considering operation materials and their corresponding proportions, then a matching scheme between engine and hydraulic torque converter was put forward based on typical operating conditions. According to the original feature data of the tested loader engine, the deducted empiric values of engine torque for full power matching and partial power matching, and the actual engine torque value consumed by loader hydraulic system, three kinds of different characteristic curves of net engine torque were obtained by using a data fitting method. After fitting the original feature data of tested loader hydraulic torque converter, according to the characteristic curves of hydraulic torque converter between efficiency, torque coefficient, moment coefficient and rotational speed ratio, the corresponding torque coefficient, moment coefficient and rotational speed ratio were obtained when the torque converter efficiency was the highest; and according to the matching principle of engine with torque converter and load calculation formula of torque converter, the corresponding torque converter diameters of matching schemes for full power, experimental power and partial power were calculated. On the basis of determining jointly working points of different engine and torque converter matching schemes, and combined with the parameter relationships between pump impeller and turbine of hydraulic torque converter, the jointly working output characteristics of engine and torque converter were obtained, then the average turbo-shaft output power and the average engine fuel consumption rate of turbine working in high efficient area for experimental power matching scheme were calculated by using integral average method, and a contrast analysis of the corresponding calculated values had been carried out among the matching schemes of experimental power, original power and partial power. The results showed that the average turbo-shaft output power of experimental power matching scheme was respectively 17.02% and 42.59% higher than those of original scheme and partial scheme, and the average engine fuel consumption rate of experimental power matching scheme was respectively 3.80% and 8.72% lower than those of original scheme and partial scheme. Therefore, the proposed matching scheme is superior to several kinds of matching schemes commonly used in power matching at present, which provides a reference for optimum design of hydraulic torque converter and proper matching between engine and hydraulic torque converter.