Rectilinear transfer mechanism with pulleys and belts

#The invention concerns a mechanism meant for transforming the rotation of a shaft into the rectilinear movement of a body in relation to a support including the bearings of said shaft. The motion transformation is provided by pulleys and belts, in particular, thin metal (foil) belts wound on cylindrical-rim pulleys.

#The invention resides in using two opposite belts staggered along the shaft axis and wound on two pulleys of the same diameter, each belt having its first end fixed on the corresponding pulley and its second end fixed directly or indirectly on the moving body, the winding direction of the two pulleys being opposite, so that the rotation of the shaft in one direction or the other causes the winding of one belt and the unwinding of the other.

#According to the conditions of use, the invention can take on at least one of two principal forms. In the case where the length of the moving body in the direction of displacement is greater than the corresponding length of the support, the two ends of the two belts are fixed on the moving body at mounting points which are far apart, from which the two belts converge towards a double pulley, both belts being situated in one plane tangent to the two pulleys.

#Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views, and wherein:

#FIG. 1 is a perspective view, partially in section, of a double displacement mechanism combining the two embodiments;

#FIG. 2 is a larger-scale transverse cut of one element of the double pulley showing the attachment of the corresponding belt; and

#According to the invention, as seen in FIG. 1, it is desirable to displace a moving body M in relation to a fixed support plate P. The moving body M is slidably mounted in the plate P by means permitting rectilinear sliding motion. For example, a roller guide 1 fixed to the moving body M includes on two opposing sides edges bevelled at 45.degree.. The roller guide 1 is carried by four rollers 2 which rotate around axes fixed to the plate P, each of the rollers including a V-shaped groove of a contour corresponding to that of the bevelled edges of the roller guide 1. Naturally, these rollers are precisely positioned and fixed so as to suppress all loose play. One can assume,for simplicity, that the moving body M travels horizontally.

#To produce rectilinear reciprocating movement of the moving body M in relation to the plate P, a shaft 3 is arranged to be driven in rotation by an appropriate electro-mechanical or hydraulic device, shown schematically by a servomotor 4 with two directions of rotation.

#According to the invention, the transformation of the rotating movement of the shaft 3 to a linear movement of the moving body M is obtained by using two belts 5 and 6, with opposite actions, staggered along the shaft axis 3 and wound on two pulleys, 7 and 8 respectively, of the same diameter, which consequently can be united in a single cylinder.