2016 Volume 3 Issue 1 Pages 15-00551
Slider-crank mechanisms are frequently used to convert between linear and rotational motion. When a slider-crank mechanism creates linear piston motion, a side force occurs between the cylinder sides and the piston head. The side force can be reduced using a Scotch yoke mechanism. However a Scotch yoke mechanism requires two parallel opposed sliders, therefore it is difficult to keep a precision and structure complicated each machine elements. This side force causes various problems, so authors have proposed an orthogonal double-slider joint mechanism to reduce the side force acting on the piston. We build three types of water-pump to investigate efficiency differences among the driving mechanism types, namely, a slider-crank mechanism with a crosshead, a Scotch yoke mechanism, and the orthogonal double-slider joint mechanism. We measure the input torque needed to drive a water-pump under same conditions for stroke, cylinder cross-section, and crank rotational speed. To investigate the influence of sliding frictional resistance acting on the crosshead, we compare results between the cases of driving by the slider-crank mechanism with a crosshead and the orthogonal double-slider joint mechanism. To investigate the influence of structural differences, we compare results between the cases of driving by the Scotch yoke mechanism and the orthogonal double-slider joint mechanism. We find that among the three mechanisms the orthogonal double-slider joint mechanism can drive the water-pump with the least input torque.
