3.3 Application of the linkages r Can you give some examples used in machinery? r Crank-rocker blender Crank-slider block: piston engine, punch r Others: bus door driving mechanism crank-shaper hand-operated well pump
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) r Please try to type the quite different applications above r They represent three different tasks r 1 Path generation: concern with the path of a tracer point. For example? r 2)function generator: the relative motion between links connected to ground is of interest. For example? r 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 1. The grashof condition(曲柄存在条件) 2. Fourbar Quick-Return(急回特性) r3 Transmission angle pressure angle (传动角与压力角) r4 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）
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 g/ A D 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
1Let $=length of shortest link L=length of longest ink P=length of one remaining ink Q=length of other remaining ink 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 pQwhen 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