Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1993-03-24
1995-01-17
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
25023114, G01D 534
Patent
active
053827929
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
The invention is based on an angle sensor of the no contact type, preferably for motor vehicles, which includes a first component which is attached to or carried along by the rotatable arrangement or device to be monitored, and a second component or measuring device which cooperates with the first component to determine the rotational displacement angle. Such angle sensors are known in principle, with the measuring of the angle being effected optically, inductively or capacitively. Also known in machine construction are magnetic couplings, for example for use in pumps employed in process technology.
SUMMARY AND ADVANTAGES OF THE INVENTION
An angle sensor according to the invention, which is a no-contact angle sensor, particularly for motor vehicles, includes a component that is carried along by the arrangement whose angular displacement is to be monitored and an optical measuring device for determining the displacement angle (.PSI.), with the measuring device including a coding disc which is rotatably mounted within a hermetically sealed housing and is magnetically coupled with the component carried along by the arrangement to be monitored. The magnetic coupling includes at least one pair of magnets, with one magnet of each pair being on the coding disc and the other magnet of each pair being on the component carried along by the arrangement to be monitored.
The angle sensor according to the invention has the advantage that hermetic encapsulation becomes possible; this provides protection against the high stresses and interferences to which such sensors may be subjected, particularly in operation in a motor vehicle. Their operational reliability is consequently increased significantly, without adversely influencing the accuracy of the sensor, since, if dimensioned correctly, practically no measuring errors occur from the magnetic circuit. The structural measures to be discussed and illustrated below permit optimization of the dynamic behavior.
The measures defined in the dependent claims provide for advantageous modifications and improvements of the basic angle sensor. Particularly advantageous in this connection is the versatility of the structural configuration while simultaneously providing for a gas-tight encapsulation of the measuring device which is susceptible to interference.
BRIEF DESCRIPTION OF THE DRAWING
Two embodiments of the invention are illustrated in the drawing and will be described in greater detail below.
FIG. 1 is a sectional view of an angle sensor according to the invention,
FIG. 2 depicts a first embodiment equipped with radially oriented magnets,
FIG. 3 shows a second embodiment equipped with axially oriented magnets, and
FIG. 4 is a curve of the restoring moment of the magnetic coupling as a function of the rotational displacement angle between the two coupling components.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a sectional view of a no-contact angle sensor operating according to the optical measuring principle, particularly for use in motor vehicles. This angle sensor includes a component 10 that is carried along by a non-illustrated, rotationally movable arrangement to be monitored which is connected to shaft 11 and a measuring device 12. Component 10 thus is driven to rotate by way of a shaft 11. The measuring device, which as a whole is marked 12, detects the rotational displacement angle 13 of the arrangement to be monitored.
Measuring device 12 includes a coding disc 14 as well as an optical scanner 16 in which a bundle 18 of optical conductors is held hermetically sealed adjacent to coding disc 14. A holder 26 is seated in a gas-tight manner in a metal cover plate 19 which is soldered in a gas-tight manner to a likewise metal housing 20. Cover plate 19 and housing 20 are preferably made of brass.
Magnets 22 that are driven by the arrangement to be monitored are fastened to the carried-along component 10 and are opposed by magnets 24 which are carried along in the interior of the gas-tight housing 20. Magnets 24 are seated on an
REFERENCES:
patent: 4767164 (1988-08-01), Yeung
patent: 4796966 (1989-01-01), Kovaleski et al.
patent: 4947035 (1990-08-01), Zook et al.
patent: 5047629 (1991-09-01), Geist
Braun Hans
Brill Klaus
Hurst Kurt
Nelms David C.
Robert & Bosch GmbH
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