Patent ID: 7063634
Filing Date: 2006-06-20
Classification: F16H

Abstract:
1. A tension-imparting device comprising: a housing having a plunger-receiving hole with an enlarged end portion; a plunger slidable in said hole, extending through said enlarged end portion, and protruding therefrom in a protruding direction, for exerting a tensioning force against a traveling flexible transmission medium; toothed racks formed on opposite sides of the plunger; a protrusion biasing spring biasing the plunger in the protruding direction; a cam-receiving ring fitted on the outside of plunger and disposed in said enlarged end portion of the plunger-receiving hole, said cam-receiving ring having a pair of grooves with oblique cam-engaging surfaces; a spring, also disposed in said enlarged end portion, biasing the cam-receiving ring in said protruding direction; a pair of wedge-shaped cam chips, also disposed in said enlarged end portion of the plunger-receiving hole, the cam chips being situated respectively in said grooves and engaged with, and slidable on, said oblique, cam-engaging surfaces of the cam-receiving ring, said cam chips having teeth engaged respectively with said toothed racks on opposite sides of the plunger; a cam guide ring, fitted on the plunger, and also disposed within the enlarged end portion of the plunger-receiving hole, for guiding and controlling disengagement of the pair of wedge-shaped cam chips from said racks; a seal plate having a central opening slidably fitting the plunger, and sealing the biasing spring, the cam-receiving ring, the cam chips, and the cam guide ring, all of which are disposed in the enlarged end portion of the plunger-receiving hole; and a plunger releasing mechanism, for temporarily holding the plunger in a retracted condition, and responsive to an external pressing force urging the plunger in a retracting direction opposite to the protruding direction, for releasing the plunger for protruding movement, in which said plunger releasing mechanism comprises a pin protruding laterally from the plunger, a loop-shaped retainer engageable with said pin, and a roll-shaped tube on the seal plate, said loop-shaped retainer being engaged with, and pivoted in, said roll-shaped tube, and movable from a first position, in which it engages said laterally protruding pin and thereby holds the plunger in its retracted condition, to a second position, in which it releases the plunger for protruding movement.