【摘要】 木田叶轮的轮叶是参与土壤相互作用的基本元件。轮叶驱动面是轮叶产生推力、承力性能的工作面。轮叶驱动面的几何形状参数对驱动轮的工作性能和整机牵引性能有重要影响。本文提出确定轮叶驱动面几何参数的两个基本原则:一是机械原理的共轭啮合基本定律,要求啮合过程节点位置不变,压力角维持一定;二是符合驱动轮的滑转滚动轨迹和规律。本文提出以滑转率δ为最基本参数建立其他参数关系式。本文对轮叶驱动面下面九个几何形状参数进行分析:顶圆、节圆、基圆、倾角、压力角、轮叶高、叶形曲率弧长、啮合线长、以及一个轮叶与土壤啮合过程中的轮子转角。本文推导出上述几何参数与滑转率的八个关系式。其中,对轮叶倾角和压力角作了详细的分析,用编程序的电子计算器Casio·Pro·Fx-1将倾角、压力角与滑转率关系式(δ=1-(2sinγ-tgγ)/γ,δ=1-cos(tgα)-tgαsin(tgα)/1-tg~2α)进行连续计算并绘出两曲线,得出交点可作为倾角与压力角最佳值γ=α=26.51°,其相应最佳滑转率值为14.87％。根据上述原则,可推算出一个轮叶与土壤啮合接触过程的轮子转角,对于压力角及倾角等于26.51°的轮叶来说,轮子转角为68.08°,这样表明叶轮的最少叶数为六个,便可保证任何时刻都有轮叶与土壤啮合接触。本文列出多年来按上述原则设更多还原

【Abstract】 The blade (lug) of a blade-wheel is the basic element to interact with the soil. The driving profile of a double-curved-profile blade is the profile to obtain thrust and lift characteristics. It’s geometrical parameters have highly significant effect on the mobility performance of the rigid wheel at wet paddy field.In order to develop and to design the geometrical parameters of the driving profile, there are two fundamental principles that must be kept in mind. The first principle is the fundamental law of conjugate action between two meshing profiles, when two profiles are designed to produce a constant angular velocity ratio during meshing, they are said to have conjugate action. In order to transmit motion at a constant angular velocity ratio, the pitch point P must remain fixed, and the line of action must remain intersected the horizontal line at a constant pressure angle. The second principle is that the rolling motion and locus of any point of a slipping wheel must be used in developing the parameters of a blade.The rate of slip of a slipping driving wheel is the main parameter which relates with all other geometric parameters of blades. It acts some thing like the ’module m’ of a gear profile.This paper analyses and deals with nine geometrical parameters of the driving profile of a blade. Those are.Top circle pitch circleBase circle Inclined anglePressure angle Radial height of profileContact length Arc length of profileRolling wheel angle within meshing The author derives the following equations to relate the nine parameters.1 . Rate of slip 5 and radius of pitch circle r, radius of top circle2 . The inclined angle (y) equation 0=1- ^-HULjSY-.3. The pressure angle (a) equationcos (tga) -tgasin (tga)b _ jTo compute the above two equations, the author develops his program using the Programmable casio fx-1 calculator, and obtains the value y and a with respect to 6, and plots the curves of the above equations. The curves intersect at a point which represents optimum value of inclined angle and pressure angle with respect to the rate of slip (y = a = 26.5%, o=14.87%) .4 . Radius of base circle (rg)rg = rcoscc = r0 (1-5) cosacos (tga) -tgasin (tga) = r0 -------- ------------- cosa5. The radial height (h)h"=r0 (1 -5) ( 1 -cosa) 6 . The arc length of profile (s) s= -i-rgtg2a0r20 sin2a 2rg7. Contact length (L)L = r0sina8. The rolling wheel angle within meshing? - L ro sina , 昬A + eA2=-^ + Y = - - - + Yrs rgFor a blade profile with 26.51? inclined angle and pressure angle, the rolling angle of wheel within meshing is 60. 08? and thus the minimum blades in one wheel are six. Six blades are sufficient to assure that there is always a blade in meshing with the soil.This paper lists out three tables of tractor test data which reveal the performance of 30? inclined angle blade wheel mounted on wheel tractors, riding tractors, and boat-type tractors. The data shows that the tractive efficiency of these three kinds of tractors with blade wheels are 48-54%, but for other wheels they are 10-43%.The author designs the optimum geometrical parameters of 26.50?blade wheels and compares them with the parameters of the 30癰lade wheels.The author hopes that the advanced theoretical study of the driving profile of a blade will give the tractor more tractive efficiency,and thus increasing the tractor’s pull and obtaining the higher fuel efficiency. The fuel saving will give from 5 to 9 % for the paddy field wheel tractors.更多还原