| 摘要 |
The contactless force coupling between a self-compensating balance and a weighing material, which, for specific reasons, has to be enclosed in a weighing cell, is carried out very simply and inexpensively by means of a single permanent magnetic field in contrast to the known complicated suspension-type coupling methods. The weighing material is connected to a ferromagnetic body which rests on a mounting in the non-ferromagnetic weighing cell. It is attracted by a permanent magnet fastened to the load arm of the balance. The determination of mass is based on the principle of the dependence of the magnetic force between two magnetic poles on the distance between these. By means of a slow change in the distance between the weighing cell and the magnet, the point of unstable force equilibrium between magnetic force and effective gravitational force, at which the mass indicated by the balance is therefore exactly equal to the sought effective mass of the ferromagnet/weighing-material system, is reached. This point can be determined very accurately by means of the jump of the system in relation to a second mounting, which jump takes place at an insignificantly smaller distance and can be observed directly by means of the balance as a discontinuous apparent change of mass.
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