| 摘要 |
A new mass transducer with electromagnetic compensation is described, comprising a load-detection part, fitted with a coil fixed to the load levers, a reference part comprising a sample weight and a second coil (called reference coil) fixed to the reference levers, a magnetic unit (yoke) with permanent magnets in the air gap whereof the coils are placed coaxially, free to move independently of one another, a control device for keeping the load coil and the reference coil in place and a device for comparing the current flowing through the coils. According to the invention, the coils are of the flattened toric type, their biggest dimension being perpendicular to the longitudinal axis of the lever arm of the load levers and the winding axis X-X of the coil lined up with the force axis. The magnetic circuit has the form of a wafer formed by two flat magnetic elements facing each other, made integral with a central plate through one or more fastening members, inside which at least one pair of permanent magnets, fitted so as to form two air gaps symmetrical to the central metal body wherein the coils are housed. The magnets are positioned so that each coil is immersed in an equiversal magnetic field, directed perpendicular to its biggest surface. |
