3.3 Application of the linkages Can you give some examples used in machinery? Crank-rocker:Blender, Crank-slider block:piston engine,punch Others:bus door driving mechanism, crank-shaper hand-operated well pump 00
3.3 Application of the linkages ◼ Can you give some examples used in machinery? ◼ Crank-rocker: Blender, ◼ Crank-slider block: piston engine, punch ◼ Others： bus door driving mechanism， ◼ crank-shaper ◼ hand-operated well pump
3.3 Application of the linkages(ct) Please try to type the quite different applications above. They represent three different tasks: ■ 1)Path generation:concern with the path of a tracer point.For example? 2)function generator:the relative motion between links connected to ground is of interest.For example? 3)motion generation:the entire motion of the coupler link is of concern.For example?
3.3 Application of the linkages(ct) ◼ Please try to type the quite different applications above. ◼ They represent three different tasks: ◼ 1) Path generation: concern with the path of a tracer point. For example? ◼ 2) function generator: the relative motion between links connected to ground is of interest. For example? ◼ 3) motion generation: the entire motion of the coupler link is of concern. For example?
3.4 Characteristics Analysis of four-bar linkages mI.The Grashof condition(曲柄存在条件) ■2.Fourbar Quick-Return(急回特性) 3.Transmission angle Pressure angle (传动角与压力角) 4.Toggle positions Dead-points (极限位置与死点) 5.Mechanical advantage(机械增益)
3.4 Characteristics Analysis of four-bar linkages ◼ 1. The Grashof condition(曲柄存在条件) ◼ 2. Fourbar Quick-Return （急回特性） ◼ 3. Transmission angle & Pressure angle （传动角与压力角） ◼ 4. Toggle positions & Dead-points ◼ （极限位置与死点） ◼ 5. Mechanical advantage（机械增益）
I.The Grashof condition(曲柄存在条件) It is used to predict b the rotation behavior or rotatability of a four-bar linkage's B inversions based only on the link lengths. Two key positions
1.The Grashof condition(曲柄存在条件) It is used to predict the rotation behavior or rotatability of a four-bar linkage’s inversions based only on the link lengths. Two key positions
1)Let S=length of shortest link L=length of longest link P=length of one remaining link Q=length of other remaining link Then if S+L<=P+Q,the linkage is Grashof and at least one link will capable of making a full revolution with respect to the ground plane. Otherwise,the linkage is non-Grashof and no link will be capable of a complete revolution relative to any other link. 2)The Grashof condition are independent from the order of the S,L,P,Q when the mechanism is assembled
1) Let S=length of shortest link L=length of longest link P= length of one remaining link Q= length of other remaining link Then if S+L<=P+Q, the linkage is Grashof and at least one link will capable of making a full revolution with respect to the ground plane. Otherwise, the linkage is non-Grashof and no link will be capable of a complete revolution relative to any other link. 2) The Grashof condition are independent from the order of the S,L,P,Q when the mechanism is assembled