Device for sampling a liquid in a tube closed by a cap
Device for sampling a liquid in a tube by means of a hollow needle ( 10 ) passing through the closing cap ( 12 ) of the tube ( 14 ), means ( 18, 20 ) with rack and toothed wheel being provided to oppose the rising of the tube ( 14 ) when the needle is extracted from the cap ( 12 ).
1. Device for sampling a liquid in a tube closed by a cap, comprising a needle displaced in translation by motor means in order to pass through the cap of the tube, means of immobilising the tube which can be displaced with the needle in order to press against the cap when the needle is descended through the cap, means for blocking means for immobilising when the needle is raised through the cap and means for unblocking means for immobilising when the needle is out of the cap, wherein the means for blocking include a toothed wheel mounted rotating about a stirrup by the intermediary of a unidirectional rotation mechanism, said stirrup being mounted pivoting around an axis between a first position where the toothed wheel is engaged with a rack parallel to the direction of displacement of the needle and a second position where it is separated from this rack, the unidirectional rotation mechanism of the toothed wheel authorising, when the toothed wheel is in the first position, a descending of the means for immobilising and prohibiting in this first position the rising of the means for immobilising.
2. Device according to claim 1 , wherein the centre of gravity of the stirrup of the toothed wheel is off centre in relation to the axis of rotation of the stirrup in such a way that the toothed wheel is brought by gravity into its first position.
3. Device according to claim 2 , the stirrup is solicited by a spring in rotation around the axis in a direction pressing the toothed wheel on the rack.
4. Device according to claim 1 , wherein the means for unblocking include a transversal finger displaced by the needle in order to come and press, when the needle is out of the cap, against the stirrup of the toothed wheel and pivot this stirrup around the axis of rotation in order to bring the toothed wheel into its second position.
5. Device according to claim 4 , wherein the transversal finger bears a contact roller bearing with the stirrup of the toothed wheel.
6. Device according to claim 1 , wherein the pivoting axis of the stirrup of the toothed wheel is mounted on a steady bearing in translation on the rack.
7. Device according to claim 6 , wherein the rack and the steady bearing are immobilised in rotation in relation to one another by a roller bearing mounted in the bearing and engaged on the rack.
8. Device according to claim 6 , wherein the steady bearing is mounted on a fixed support and the rack is fastened to the means for immobilising.
9. Device according to claim 6 , wherein the rack is mounted on a fixed support and the steady bearing is fastened to the means for immobilising.
10. Device according to claim 1 , wherein the means for unblocking include means for raising means for immobilising when the needle is out of the tube.