Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1999-07-30
2002-08-13
Patidar, Jay (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207200
Reexamination Certificate
active
06433538
ABSTRACT:
PRIOR ART
The invention is based on a measuring device for contactless determination of an angle of rotation as generically defined by the preamble to the independent claims. From published French Patent application FR 90 15 223, a measuring device is known in which a stator and a rotor are moved relative to one another. There is a small air gap between the stator and the rotor, each of which is made of magnetically conductive material. A first annular permanent magnet, which is radially polarized, is disposed in the rotor over a length of 180°. In the remaining region of the stator, also encompassing 180°, there is a second annular permanent magnet of opposite polarization. The stator also has two diametrically opposed air gaps. In at least one of these air gaps, there is a Hall sensor. In the rotary motion of the rotor, relative to the stator, the intensity of the magnetic field passing through the Hall sensor changes. The linear measurement range of the measurement signal thus generated is limited to a magnitude of ±75°, however. This linear measurement range also has a change of sign. This change of sign could possibly be corrected, at some expense, in an adjacent electrical circuit.
From German published, non-examined Patent Application DE-OS 196 34 381.3, published after the filing date of the present application, a sensor is also known that is disposed in three planes, one above the other. The rotor forms the middle plane and comprises the carrier plate for a permanent magnet. The carrier plate itself comprises magnetically nonconductive material, so that the magnetic flux passes via the other two planes, that is, the stator, and is controlled with the aid of two spacers, which are disposed between the two planes of the stator. With this sensor, a relatively wide angular range can be measured without a change of sign, but it is not suitable for measurements over 180°.
ADVANTAGES OF THE INVENTION
The measuring device of the invention for contactless determination of an angle of rotation, having the characteristics of the body of the independent claim, has the advantage over the prior art that the sensor makes it possible to determine an angle of rotation of over 200°. The virtually linear measurement line has no change of sign. The zero point of the induction is equal to the zero point of the angle measurement. Because of the structural arrangement of the flux conductors and the air gaps, the measurement range can be varied to over 240°. If the measurement gap is curved, then the permanent magnet can be smaller than the angle to be characterized. If the spiral permanent magnet system is smaller than the angle to be characterized, then flux elements for example need not be a full circle or have other similar complete shapes. Furthermore, the drive shaft need not be disposed at the center of the sensor.
Advantageous refinements of and improvements to the measuring device defined by the independent claim are possible with the provisions recited in the dependent claims.
REFERENCES:
patent: 6130535 (2000-10-01), Herden et al.
patent: 196 34 281 (1998-02-01), None
Gauger Tilman
Klotzbuecher Thomas
Reichl Asta
Patidar Jay
Robert & Bosch GmbH
Striker Michael J.
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