Design of Chassis Transmission and Steering System for Hilly Tractor
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摘要:
针对拖拉机在丘陵山区适应性差，田间地头转向半径大、易损害作物，耗时长和效率低等问题，设计了一种可原地转向的504型丘陵山地拖拉机底盘。整机采用四驱轮式行走系统，前进和后退速度为0～5 km/h，可无级调速。传动系统采用机械式“H”型传动路线，通过纵梁内外双轴的设计将左右两侧的驱动力独立分开。采用离合器式转向分动器，通过转向分动箱内的牙嵌式离合器两两组合，完成底盘不同作业状态的控制，两路动力通过正转+正转、反转+反转、正转+反转和反转+正转4种状态的组合，实现拖拉机的前进、倒退、左右大小半径转向和原地转向。结果表明，整机最大牵引力为10.78 kN，最大及最小总传动比分别为732.50和73.25，前后驱动桥传动轴最高及最低转速分别为31.07和6.21 r/min。底盘的轮距和轴距比值为1，其所受滑移阻力矩与滚动阻力矩之和小于其所受驱动力矩，可在窄小地头实现原地转向，减小拖拉机田间作业的空行程，提高作业效率，有效保护农作物。
Abstract:Aiming at problems of poor adaptability of tractors in hilly and mountainous areas, large turning radius in field, easy to damage crops, long time-consuming and low efficiency, a 504-type hilly tractor chassis that could turn in situ was designed．Whole machine adopted a four-wheel drive walking system, with forward and backward speeds of 0-5 km/h and stepless speed regulation．Transmission system adopted mechanical "H" transmission route, and driving forces on the left and right sides were separated independently through design of inner and outer double shafts of longitudinal beam．Clutch type steering transfer gear was used to complete control of different working states of chassis through combination of two tooth type clutches in steering transfer box．The two-way power realized the forward, reverse, left and right radius steering and in-situ steering of tractor through combination of four states: forward rotation + forward rotation, reverse rotation + reverse rotation, forward rotation + reverse rotation, reverse rotation + forward rotation．Results showed that the maximum traction force of whole machine was 10.78 kN, the maximum and minimum total transmission ratios were 732.50 and 73.25, respectively．The maximum and minimum speeds of front and rear drive axle drive shafts were 31.07 and 6.21 r/min, respectively．Ratio of wheelbase to wheelbase of chassis was equal to 1, and sum of sliding resistance moment and rolling resistance moment of chassis was less than driving moment of chassis, which could realize in-situ steering in narrow ground, reduce empty travel of tractor in field operation, improve operation efficiency and effectively protect crops．
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Keywords:
- hilly tractor /
- transmission system /
- steering system /
- spin turn
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图 1 504型丘陵山地拖拉机整体结构
1. 动力输出 2. 后驱动轮 3. 齿轮传动箱 4. 后轮边传动箱 5. 转向分动箱 6. 后驱动桥 7. 上梁 8. 连接架 9. 制动装置 10. 纵梁车架11. 前驱动桥 12. 前轮边传动箱 13. 发动机 14. 前驱动轮 15. 机架16. 无级变速箱 17. 齿轮减速控制箱 18. 减速器
Figure 1. Overall structure of 504-type hilly tractor
图 2 504型丘陵山地拖拉机总体传动路线
Figure 2. Overall transmission route of 504-type hilly mountain tractor
图 4 驱动桥和中央传动结构
1. 轮边直齿轮 2. 驱动半轴 3. 换向锥齿轮 4. 实心轴 5. 轮胎6. 等速万向节 7. 空心轴动力输出
Figure 4. Structure of drive axle and central transmission
图 5 504型丘陵山地拖拉机原地转向传动系统
注：实线传动路线为底盘左侧驱动力，虚线传动路线为底盘右侧驱动力
Figure 5. In-situ steering transmission system of 504-type hilly mountain tractor
图 6 转向分动器机构展开示意
Figure 6. Schematic diagram of expansion of steering transfer mechanism
图 7 转向分动器直线行驶传动原理
Figure 7. Steering transfer case linear driving transmission principle
图 8 转向分动器原地转向传动原理
Figure 8. Steering transfer case in-place steering transmission principle
表 1 各级传动比分配方案
Table 1. Distribution plan of transmission ratios at all levels
传动方式 无级变速箱 主减速器 动力输出减速器 中央传动 低—高 传动比 1.00～5.00 77.24 2.40 1.00 
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表 2 转向机构不同工况分析
Table 2. Analysis of different working conditions of steering mechanism
转向形式 离合器组合状态 内外轴转向 左右驱动轮 直线前进行驶（R=∞） 接合C1、C4，断开C2、C3 轴1正转，轴2正转 同向等速 直线倒退行驶（R=∞） 接合C2，C3，断开C1、C4 轴1反转，轴2反转 同向等速 原地左转向（R=0） 接合C1、C3，断开C2、C4 轴1正转，轴2反转 反向等速 原地右转向（R=0） 接合C2、C4，断开C1、C3 轴1反转，轴2正转 反向等速 大小半径左转向（0≤R≤A/2）＆（R≥A/2） 接合C1、C3，断开C2、C4 轴1正转，轴2反转 反向等速 大小半径右转向（0≤R≤A/2）＆（R≥A/2） 接合C2、C4，断开C1、C3 轴1反转，轴2正转 反向等速 注：R为底盘转向半径，mm；A为两驱动轮中心距，mm。
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