Electricity: measuring and testing – Electrical speed measuring – Including speed-related frequency generator
Patent
1997-06-20
1999-12-28
Strecker, Gerard
Electricity: measuring and testing
Electrical speed measuring
Including speed-related frequency generator
324173, 3242072, 32420726, 324202, G01P 2102, G01P 348, G01B 714
Patent
active
060086386
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to sensor elements for determining displacements, motional speeds, and rotational speeds in the field of mechanical engineering, in particular in the automotive vehicle industry and, more particularly, in the range of application of controlled brakes, for determining the rotational speeds of wheels.
BACKGROUND OF THE INVENTION
Sensor devices for determining the rotational speeds of wheels are known. Normally, the devices include an incremental encoder which is mechanically coupled to the rotating part, and a sensor which scans the encoder in a non-contact manner. Ferromagnetic toothed wheels or ferromagnetic discs are used as encoders. When sensors are used in wheel bearings, it is customary to employ magnetized structures, for example, an annular or circular arrangement of adjacent north and south poles, embedded in a mechanical carrier.
It is most common to use so-called "passive" sensors according to the reluctance principle. The sensors include a combination of a copper coil with a permanent magnet which is magnetically coupled to the encoder. The encoder modulates the magnetic coupling reluctance synchronously with movement. An alternating voltage, synchronous with movement, is induced in the copper coil in the way of a dynamo, and the frequency of the alternating voltage is evaluated as a measured quantity. The induced signal voltage fades away during standstill and will possibly adopt undesirably high values at high speeds.
To avoid such high voltages, so-called "active" sensors, have been developed. Sensors of this type are described in German patent application No. 41 35 789, for example. The sensors are a combination of a magnetostatically sensitive element and a permanent magnet which is magnetically coupled to the encoder. In this arrangement also, the encoder modulates the magnetic coupling reluctance or, in the case of the magnetized encoder, the field direction, synchronously with movement. The sensor element responds to the variations of the flux density or to the movement of a field vector. Examples in the art of such basic elements are Hall probes or magneto-resistive permalloy structures. The signal amplitude of active sensors of this type is independent of the speed of the encoder. Active sensors require for operation an electric energy which is supplied by an electronic controller. Technical methods involving a three-conductor feed-in or a two-conductor feed-in are known in the art. The three-conductor version supplies a signal voltage to the input of the electronic controller, while the two-conductor version furnishes a signal current.
Active sensors of the current type limit the sensor information available to them to one single parameter, the signal frequency. An internal amplifier trigger circuit generates a binary output signal with two constant amplitude values in the area of a defined, permissible air slot between the sensor and encoder, irrespective of the size of the air slot. The change in flanks of the amplitude values is evaluated, but the signal itself does not indicate the changed values. However, the signal discontinues abruptly when the permissible air slot size is exceeded because in this event the induced sinusoidal input signal falls short of a sensor-inherent hysteresis threshold, and the sensor stops responding.
A device for the adjustment of the air slot size, as disclosed in German patent application No. 40 33 064, ensures a proper mounting position of the sensor and maintains the permissible air slot size. The sensor is fitted in a sleeve-shaped mounting support and is urged by a compression spring with a flange against a corresponding flange of the mounting support in the direction of the encoder. The flange of the sensor includes a plurality of similar, axial teeth, while the flange of the mounting support includes two groups of axial indentations, the number of which corresponds to the number of teeth. When the sensor is installed, its teeth are placed in the group of the deep indentations, and the assembly of
REFERENCES:
patent: 3923030 (1975-12-01), Luteran
patent: 4293814 (1981-10-01), Boyer
patent: 4902970 (1990-02-01), Suquet
patent: 5043658 (1991-08-01), Braschel et al.
Japanese Abstract Application No. JP860245445. Publication date May 2, 1988.
Japanese Abstract Application No. JP900299140. Publication date Jun. 19, 1992.
Article "Automatic Testing of Sensors in ABS Systems"; Technisches Messen 58 (1991) 7/8.
Article "Drehzahlerfassung mit Differenz-Hall-IC"; Elektronik Apr. 1991.
Bleckmann Hans-Wilhelm
Lohberg Peter
Loreck Heinz
ITT Manufacturing Enterprises Inc.
Strecker Gerard
LandOfFree
Active motion sensor having post-assembly air slot signal adjust does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Active motion sensor having post-assembly air slot signal adjust, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Active motion sensor having post-assembly air slot signal adjust will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2384787