| 摘要 |
In a first aspect the invention relates to a drill-string-forming drill tube which includes a channel (15) intended for passing flushing liquid, inside of which there is a restriction which forms a seat (14) for a valve body (16) serving as a check valve. Said drill tube comprises, in addition to a partly spherical skittle member (17) for engagement in the seat (14), two or more tangentially separated blocking elements (21). The purpose of said elements is, when flushing liquid is fed from the valve seat towards a second restriction distanced therefrom, to stop the valve body against said second restriction without sealing thereagainst. Therefore, one and the same drill tube may be used for upwardly directed as well as downwardly directed drilling. In a second aspect, the invention relates to the valve body as such. |
