Patent Number: 
Section: claims

1. A tight connection device for tight connection between a system for feeding with powdery or granular materials and a container fitted with a filling orifice, where the said device includes:a stationary connection portion intended to be connected to the feed system,a moving connection portion which moves relative to the stationary connection portion along a vertical direction, said moving connection portion being intended to be connected to the filling orifice of the container, the moving connection portion including:a first part forming a support which is configured to move relative to the stationary connection portiona second part forming a downstream end of the moving connection portion and supporting at least one seal to accomplish a tight connection by contact with the contour of the filling orifice, said first part and said second part being connected by flexible sealing system such that the downstream end of the moving connection portion and the stationary connection portion can be mechanically disengaged,a device for limiting the movement of the second part away from the first part, said device being active when the second part is not in contact with the contour of the filling orifice, and being inactive when the second part is in contact with the contour of the filling orifice. 2. A tight connection device according to claim 1, in which the limitation device includes radial pins and a shoulder upstream from the pins such that, when the second part comes into contact with the contour of the filling orifice the shoulder and the pins separate. 3. A tight connection device according to claim 1, in which the stationary connection portion forms a hopper collecting the materials, and in which the first part of the moving connection portion includes a supporting ring assembled in sliding and tight fashion around the collecting hopper and in which the second part forms a seal ring, the seal ring and the supporting ring being connected by a tight bellows providing the mechanical disengagement between the stationary connection portion and the downstream end of the moving connection portion. 4. A tight connection device according to claim 3, in which the seal supported by the seal ring is formed by a lip seal assembled in a groove. 5. A connection device according to claim 3, in which the supporting ring is extended by a pipe conveying in the direction of the seal ring. 6. A tight connection device according to claim 5, comprising a seal between the conveyance pipe and the collecting hopper to provide tight sliding. 7. A tight connection device according to claim 3, including a device to cause the supporting ring to slide axially relative to the stationary connection portion. 8. A tight connection according to claim 3, in which the bellows is assembled on the supporting ring by means of a mounting flange, and the upstream and downstream ends of the bellows are attached on the mounting flange and on the seal ring, respectively, by means of clamp connections. 9. A tight connection device according to claim 8, in which the mounting flange is secured axially to the supporting ring by a bayonet system. 10. A tight connection device according to claim 5, including a ventilating aperture in the supporting ring, and communicating with the interior of the jar through a passage demarcated between the bellows and the conveyance pipe. 11. A filling system including a tight connection device according to claim 1, pipes for feeding with powdery or granular materials upstream to the tight connection device, and a weighing device supporting the container, the feed pipes being connected to the stationary connection portion. 12. A filling system according to claim 11, in which the feed pipes are of the vibrating chute type. 13. A filling system according to claim 12, in which the vibrating chutes are operated so as to deliver the materials at high speed at the start of the filling, and then to deliver the materials at slower speeds when the delivered quantity is close to the desired quantity. 14. A filling system according to claim 11, in which the weighing system is able to bring the filling orifice of the container close to the tight connection device. 15. A jar-filling system according to claim 11, with a mixture of powdery materials including uranium oxide and/or plutonium oxide or a mixture of these, and intended for the production of nuclear fuel. 16. A method of filling a container by means of the system for filling a container according to claim 11, including the following steps:positioning of the container beneath the tight connection device,weighing of the container,bringing the tight connection device close to the container's filling orifice,bringing the seal ring into contact with the contour of the filling orifice in order to make a tight connection,weighing of the assembly formed by the container and the seal ring,arrival of the material or materials. 17. A filling method according to claim 16 in which, between each filling by a material, the seal ring is separated from the contour of the filling orifice and the container with its content is weighed.