Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1998-10-30
2001-05-15
Patidar, Jay (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S174000, C324S226000, C384S448000
Reexamination Certificate
active
06232772
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a device for measuring the rotation of a rotating element and, more particularly, to a device which has an encoder element that is carried by the rotating element and that cooperates with a sensor unit connected to a stationary element.
Conventionally, devices for measuring the angular position or speed of a rotating element include a sensor unit; immobile with respect to a measuring reference frame, cooperating with an encoder put in rotation by the rotating element, to provide a signal to an electronic processing center. A disadvantage of this type of device is that the active surface of the encoder facing the sensor, which is most often a multipolar magnetic surface or a surface with regularly spaced perforations possibly covered with a plastic or rubber-type protective film, is particularly sensitive to deposits of all sorts, possibly leading to disturbances of the generated signal. In particular, during the operation of such devices in an unfavorable environment, contaminating particles can adhere by projection or by magnetic attraction to the encoder.
A known approach to remedy this disadvantage is to enclose the encoder in a sealed enclosure in order to prevent the introduction of contaminating particles during operation. An example of this type of device is described and illustrated in the document EP-A-0 675 364 filed by The Timken Company. However, that proposed solution leads to the realization of a device which is complex and expensive to produce and does not make it possible to eliminate contaminating particles from depositing on the encoder during the phase of assembling the device in workshops.
Also proposed, as described and illustrated in the French patent application FR-A-2 730 566 filed by SKF, is a magnetic encoder device for a speed sensor in which the magnetic encoder is attached to a protective element. However, the thickness of the protective element increases the air gap between the magnetic encoder and the sensor and reduces the quality of the magnetic field received by the sensor, which makes the device more sensitive to exterior disturbances and reduces its range of operation.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
SUMMARY OF THE INVENTION
In one aspect of the invention, this is accomplished by providing a device for measuring the rotation of a rotating element comprising an encoder element, a sensor unit, and a scraping means. The encoder element rotates with the rotating element, and the sensor unit is connected to a stationary element. The scraping means cooperates with a surface of the encoder element in order to remove contaminating particles from the surface of the encoder element before the surface of the encoder element passes in front of the sensor unit.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.
REFERENCES:
patent: 4400890 (1983-08-01), Ohkubo et al.
patent: 4631403 (1986-12-01), Rieder et al.
patent: 5157329 (1992-10-01), Brauer
patent: 5640087 (1997-06-01), Alff
Liatard Bernard
Nantua Rene
Riviere Isabelle
Andersen Henry S.
Bigler John C.
Patidar Jay
The Torrington Company
LandOfFree
Device for measuring the rotation of a rotating element does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for measuring the rotation of a rotating element, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for measuring the rotation of a rotating element will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2564744