Patent ID: 6035994
Filing Date: 2000-03-14
Classification: B65G

Abstract:
A conveyor comprising an endless conveyor belt driven at constant speed and passing over a pair of fixed drums (R2,R4) and over a pair of drums (R1,R3) that can move in translation parallel to the conveyor belt and means of driving the mobile drums back and forth driving these drums, in the opposite direction to the travel of the belt, at a speed equal to half of the constant speed of the belt in such a way that the speed of one section of the belt relative to a fixed point is temporarily equal to zero, wherein the conveyor belt forms a main loop between one of the fixed drums (R4) and one of the mobile drums (R1) and, within the main loop, a secondary loop between the other fixed drum (R2) and the other mobile drum (R3); and wherein said conveyor further comprises two auxiliary rolls (R5,R6) close together situated above and between the drums (R2,R3) of the secondary loop and forming return rolls for the upper strand of the conveyor belt toward the drums of the auxiliary loop and dividing the upper strand of the conveyor belt into two coplanar sections, one of variable speed and the other of fixed speed, said rolls also being able to move as one, in translation parallel to the conveyor belt; wherein the means of driving the translationally mobile drums (R1,R3) back and forth are arranged in such a way that in a first phase the mobile drums are shifted in the opposite direction to the conveying at a speed equal to half the constant speed of the belt, then in a second phase, in the direction of conveying with an increase, then a decrease in speed, so that objects (P) can be deposited on a zero-speed section, then driven at the constant speed; and wherein the conveyor further comprises means of driving the auxiliary rolls (R5,R6) back and forth, these means being synchronized with the means for driving the mobile drums back and forth, in such a way that the shifting of the auxiliary rolls in the direction of travel of the conveyor belts, at the same time as driving the mobile drums in the same direction, allows the objects driven by the variable-speed section to catch up with the objects driven by the constant-speed section.