Patent ID: 7137729

Claim:
A gravimetric dosing apparatus comprising: a support frame; a plurality of loading hoppers for a respective granular material to be dosed, each carried by said support frame and provided with a respective discharge outlet and an opening-closing device for their respective discharge outlet; inclined calibration flaps disposed at each loading hopper discharge outlet, the calibration flaps being sized and positioned to prevent material discharged by the hoppers from falling out laterally of the respective opening-closing device; a weighing hopper including a discharge outlet and an opening and closing device for its respective discharge outlet and arranged in cascade with respect to said loading hoppers to receive from at least two of said hoppers dosed quantities of different granular materials; a support element articulated to said frame and designed to overhangingly support said weighing hopper; transducing means located outside said frame between said frame and said articulated support element and designed to generate output signals proportional to the weight of the material discharged into said weighing hopper; a mixing assembly carried by said support frame and arranged in cascade with respect to said weighing hopper, whereby dosed and weighed granular material is received therefrom; and a program control unit that receives input signals from said transducer means and that program controls said opening-closing devices, wherein each of said opening-closing devices comprises a pair of opening and closing bucket-like elements articulated to one another about a common articulation axis, a reciprocating actuator means, and a fork-shaped linkage member having one fork-shaped end pivoted to said bucket-like elements, respectively and having an opposite end pivoted to said reciprocating actuator means, thereby obtaining short response times of said opening-closing device.