| 摘要 |
<p>Device for recognising foreign bodies in a crop stream which is conveyed by a conveying roller (21) and a prepressing roller forming between them a conveying gap having a width in each case matched to the crop quantity, with a metal detector (1) which covers the conveying gap of the conveying track (B) and which consists of at least one permanent magnet (M) which extends transversely relative to the conveying direction and is arranged with one pole (PM) near the conveying gap and directed towards the latter and around which is arranged a sensor winding (S1), the metal-detector signal of which is fed to a threshold switch, the output signal of which is applied to a cut-off means which stops the conveying roller (21) when the metal-detector signal exceeds a predetermined threshold value. The permanent magnet (PM) is arranged centrally in the recess of a U-shaped yoke (J) made of ferromagnetic material, and the free yoke-leg ends form secondary poles (PZ, PA) which terminate on the run-in side and on the run-off side of the middle pole (PM) in relation to the conveying direction. Various designs of the arrangement and of the wiring are specified. <IMAGE></p> |
