单轨道山地果园运输机齿条齿形优选

为减小单轨道山地果园运输机能耗及提高运输效率,该文基于动力学理论建立了运输机驱动轮与轨道齿条啮合的动力学模型,并设计、加工制造了链轮齿形齿条、销轮齿形齿条、摆线齿形齿条。以运输机驱动轮旋转角速度、轨道坡度、齿条齿形为考察因素,以驱动轮与不同齿形齿条啮合时所需提供的驱动扭矩为评价指标,探究齿条齿形对单轨道山地果园运输机力学性能的影响,得到在相同条件下驱动轮与链轮齿形齿条啮合时的驱动扭矩最小,且波动幅度最小。在驱动轮转速为+88.08 rad/s、轨道坡度分别为+0?、+6?、+12?时,驱动轮与链轮齿形齿条啮合时的驱动扭矩均值较驱动轮与圆弧齿形齿条啮合时的驱动扭矩均值分别减小33.82%,33.45%,21.59%;在驱动轮转速为-88.08 rad/s、轨道坡度分别为-0?、-6?、-12?时,驱动轮与链轮齿形齿条啮合时的驱动扭矩均值较驱动轮与圆弧齿形齿条啮合时的驱动扭矩均值分别减小35.55%,27.24%,30.43%。试验结果表明,链轮齿形齿条综合性能最优,较圆弧齿形齿条更适宜用于单轨道山地果园运输机的轨道运输中。该研究为单轨道山地果园运输机轨道的结构优化设计提供了参考。

Optimization of rack tooth forms of monorail mountain orchard transporter

Abstract: Due to the rugged terrain, there are many difficulties in the transportation of fruits and materials in hilly lands in the south of China. In order to solve the problem, self-propelled monorail mountain orchard transporter and its corresponding rail were designed and manufactured. However, in reality, the accumulative pitch error of tooth is unavoidable due to uncertainties such as manufacturing and tolerances, assembly errors and wear. And the driving wheel is the main power-consumption component. In order to reduce energy consumption and cost of transport, and increase transport efficiency and the mechanical property of the transporter, it is of great significance to research the influence of the rack tooth forms on the mechanical property of self-propelled monorail mountain orchard transporter and attempt to find the optimal rack tooth form. The paper designed another 3 kinds of tooth forms, which were chain wheel tooth form, pin tooth form and cycloidal tooth form. The original tooth form is arc tooth form, which is very sensitive to center-distance error and pitch error. And the 2 errors have great impact on the mechanical property. Meanwhile, the dynamic models of the transmission system including the driving wheel and racks were established based on the dynamic theory. As the trend of the driving torque variation is the same with the resistance torque variation which is not convenient to be measured, the experiment was carried out with tooth forms, rail gradients and angular velocity as experiment factors and with the driving torque as assessment index. The experiment was conducted from July 10 to July 22, 2017 at the Machinery Electronic Engineering Training Center in Huazhong Agricultural University. A torque sensor and a data acquisition and analysis system were used to measure the driving torque. Four kinds of racks were manufactured and spot welded to the rails, and the relation between the tooth forms and the resistance torque of the driving wheel was investigated while engaged with the racks. Experimental results indicated that the tooth forms had great influence on the driving torque, as on the resistance torque. For the 4 racks, the driving torque and the amplitude of the driving torque were the least when the driving wheel was engaged with the rack of chain wheel tooth form, while the largest when the driving wheel was engaged with the rack of pin tooth form. Contribution to the average driving torque and the fluctuation range of the driving torque, from small to large order, was chain wheel tooth form, cycloidal tooth form, arc tooth form and pin tooth form in identical condition. Under the working condition that the (rear drive) transporter moves forward along the level track at +88.08 rad/s, the average driving torque was decreased by 20.80% when the driving wheel was engaged with the rack of cycloidal tooth form than the rack of arc tooth form, while increased by 158.73% when the driving wheel was engaged with the rack of pin tooth form than the rack of arc tooth form. Compared with the rack of arc tooth form, experimental results showed that the rack of chain wheel tooth form had a better comprehensive performance by decreasing the average driving torque by 33.82%, 33.45% and 21.59% respectively under the condition that the angular velocity of the drive wheel was +88.08 rad/s, and the rail gradients were +0°, +6°, +12°, respectively; while by 35.55%, 27.24% and 30.43% respectively under the condition that the angular velocity of the drive wheel was ?88.08 rad/s, and the track gradients were ?0°, ?6°, and ?12°, respectively. By the experimental results, the rack of chain wheel tooth form is more suitable for the rail transport. This research provides the important reference for the structural optimization design of the rail.