Patent ID: 7526976

Claim:
A periodical driving system comprising: a circular wheel having a top surface portion and a plurality of high portions extending from the top surface portion at an equal angular interval, the high portions located at a distance from an outer periphery of the wheel and a low portion defined between each high portion and the outer periphery of the wheel, an open space defined between the low portion and an end of the high portion, a plurality of recesses defined between the high portions and opening to the outer periphery of the wheel, an inner bottom of each recess being lower than the low portions, each recess defined by two inner sides and each inner side including an inward curved section so as to form a convergent opening in the outer periphery of the wheel, and a driving disk having a disk body which has a disk surface located corresponding to the top surface portion of the wheel, two driving pins extending from the disk surface and each driving pin having a cylindrical base portion extending from the disk surface and a protrusion extending axially from a distal end of each base portion, a height between the distal end of the base portion and a distal end of the protrusion being higher than a height from the inner bottom of the recess to the low portion, the driving pins being freely moved through the spaces and the entering into the recesses via the openings so as to push the inner sides of each recess, the two protrusions being in contact with the two curved sections of the two recesses when the wheel is in stationary status, one of the two protrusions moving out from the recess via the opening and the other protrusion moving toward a curved inner end of the recess corresponding thereto when the wheel is rotated.