in (3-9)Р则斗杆的作用力臂Рe2=l9∠DEF (3-10)Р显然斗杆的最大作用力臂e2max = l9,此时θ2 = COS-1(l9/l8),L2 = sqr(l82-l92)Р3. 3 铲斗的运动分析Р铲斗相对于XOY坐标系的运动是L1、L2、L3的函数,现讨论铲斗相对于斗杆的运动,如图3-5所示,G点为铲斗油缸与斗杆的铰点,F点为斗杆与动臂的铰点Q点为铲斗与斗杆的铰点,v点为铲斗的斗齿尖点,K点为连杆与铲斗的饺点,N点为曲柄与斗杆的铰点,M点为铲斗油缸与曲柄的铰点,H点为曲柄与连杆的铰点[1]。Р铲斗连杆机构传动比iР利用图3-3,可以知道求得以下的参数:Р在三角形HGN中Р α22 = ∠HNG = COS-1[(l152+l142-L32)/2×l15×l14]Рα30 = ∠HGN = COS-1[(L32+ l152- l142)/2×L3×l14]Рα32=∠HNG = π- ∠MNG - ∠MGN =π-α22-α30 (3-11)Р在三角形HNQ中РL272 = l132 + l212 + 2×COSα23×l13×l21Р∠NHQ = COS-1[(l212+l142- L272)/2×l21×l14] (3-12)Р在三角形QHK中Рα27 = ∠QHK= COS-1[(l292+l272-L242)/2×l29×l27] (3-13)Р在四边形KHQN中Р∠NHK=∠NHQ+∠QHK (3-14)Р铲斗油缸对N点的作用力臂r1Рr1=l13×Sinα32 (3-15)Р连杆HK对N点的作用力臂r2Рr2=l13×Sin∠NHK (3-16)Р而由r3 = l24,r4 = l3 有[3]Р连杆机构的总传动比Рi = (r1×r3)/(r2×r4) (3-17)Р显然3-17式中可知,i是铲斗油缸长度L2的函数,用L2min代入可得初传动比
全文预览
