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US 4,229,696 AGranted
Sensor for measuring magnetic field changes
OwnerAdolf G. Gustafsoninventor
Life of this patent
Estimating the term…
Abstract
A sensor for measuring the change of a magnetic field comprises a magnet for generating a constant magnetic flux, and magnetically conductive members magnetically coupled to the magnet for producing first and second magnetic fields, the first magnetic field passing through an object and the second magnetic field not passing through said object, the object being of a material which influences the first magnetic field. A magnetic field measuring device located in the second magnetic field to measure the second magnetic field and to indicate a change in the second magnetic field as a result of the first magnetic field being influenced by the object. A magnetically conductive outer shielding member, which may be one of the magnetically conductive members, is provided.
Claims20
Sensor for measurement of a distance to a magnetically conductive object comprising:
- means (2;
- 22;
- 19, 20) for generating a substantially constant magnetic flux, said magnetic flux generating means including a permanent magnet having north and south poles which are disposed on an axis substantially parallel to the surface of an object (1) the distance to which is to be measured;
- magnetic flux guiding means including at least two magnetically conductive magnetic flux guiding members (3, 4;
- 21, 23) magnetically coupled to said magnetic flux generating means (2;
- 22) and arranged in the vicinity of said object (1), said magnetic flux guiding means having an end at least adjacent said object (1) and an end remote from said object (1);
- said magnetic flux generating means being arranged to provide a first magnetic field passing through said object (1) and a second magnetic field which is directed away from the object (1) and which does not pass through said object (1), said magnetic flux guiding means guiding said first and second magnetic fields in two directions which are mutually opposed by substantially 180.degree.;
- an outer magnetically conductive member (15';
- 23;
- 25) surrounding said magnetic flux generating means and at least one of said magnetic flux guiding members to shield said sensor against environmental electric fields, said at least one magnetic flux guiding member being an integral uninterrupted elongated member;
- and
- a single magnetic field measuring means (5) located in said second magnetic field and in an air gap positioned close to the end of the magnetic flux guiding means which is located remote from said object (1) so as to substantially not be influenced by heat generated in the vicinity of said object, said first and second magnetic fields varying in mutually inverse relationship as a function of variation in the distance between said object and said sensor;
- said permanent magnet being slideably mounted between said at least two magnetic flux guiding members, whereby the position of said permanent magnet relative to said magnetic flux guiding members determines the measuring sensitivity of the sensor.
10 more elements
Sensor for measurement of a change of a magnetic field comprising:
- means (2) for generating a substantially constant magnetic flux, said magnetic flux generating means comprising a first permanent magnet (19) and a second permanent magnet (20);
- magnetic flux guiding means comprising at least first (3) and second (4) magnetically conductive magnetic flux guiding members which are magnetically coupled to said first and second permanent magnets and which are arranged in the vicinity of a magnetically conductive object (1), said first permanent magnet (19) being magnetically connected to said first magnetically conductive member (3), and said second permanent magnet (20) being magnetically connected to said second magnetically conductive member (4);
- said first and second magnetically conductive members and said first and second permanent magnets cooperating to provide a first magnetic field passing through said object (1) and a second magnetic field which does not pass through said object (1);
- an outer magnetically conductive member ( ) surrounding said first and second permanent magnets and at least one of said first and second magnetically conductive flux guiding members to shield said sensor against environmental electric fields;
- a magnetic field measuring means (5) located in said second magnetic field for measuring said second magnetic field, said first and second magnetic fields varying in mutually inverse relationship as a function of variation in the distance between said object and said sensor;
- and
- said magnetic flux guiding means further comprising a third magnetically conductive member (12) magnetically connecting said first and second magnetically conductive members (3, 4) together, said third magnetically conductive member (12) being arranged to guide said first magnetic field to run through said object (1) and said second magnetic field to said magnetic field measuring means (5);
- said first and second permanent magnets (19, 20) being located on those sides of said first and second magnetically conductive members (3, 4) which are located farthest away from each other and from said third magnetically conductive member (12).
5 more elements
Dependencies are inferred from the claim text.