点,建立如图2-4所示的直角坐标系DXY,各点的坐标如下:D(0,0)B(-78,78)B'(78,78)C'(130,130)O(225,Oy)C(-130,130)则:OB=(-303,78-Oy)OB'=(-147,78-Oy)BB'=(156,0)OC=(-355,130-Oy)OC'=(-95,130-Oy)OD=(-225,-Oy)由余弦定理得:解之得:Oy1=239.4193Oy2=30.7806Oy3=562.0679Oy4=-291.8679图2-5①当Oy1=239.4193时:OA=OA'=70.1006mmAB=A'B'=250.3546mmOB'=180.2540mmOB=320.4552mmOC'=96.0632mmB'C'=104mmOC=355.2860mm机构在左极限位置时,在ΔOB'C'中(如图2-5所示),可算得此时机构的传动角:机构在右极限位置时,在ΔOBC(如图2-5所示)中,可算得此时机构的传动角:所以,,不满足设计要求,故舍去。②当Oy2=30.7806时:OA=OA'=70.1006mmAB=A'B'=250.3546mmOB'=180.2540mmOB=320.4552mmOC'=216.3583mmB'C'=104mmOC=404.7356mm机构在左极限位置时,在ΔOB'C'(如图2-5所示)中,可算得此时机构的传动角:机构在右极限位置时,在ΔOBC(如图2-5所示)中,可算得此时机构的传动角:由于,,故满足设计要求。③当Oy3=562.0679时:OA=OA'=35.9956mmAB=A'B'=487.5601mmOB'=451.5646mmOB=523.5557mmOC'=350.0392mmB'C'=104mmOC=489.4154mm机构在左极限位置时,在ΔOB'C'(如图2-5所示)中,可算得此时机构的传动角:
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