Method and apparatus for preventing contamination from affecting magnetic field sensors
First Claim
Patent Images
1. A power transmission unit comprising:
- a rotatable element for transmitting power through the power transmission unit;
a magnet for creating a magnetic flux that develops frequency variations proportional to a rotational velocity of the rotatable element; and
a magnetic field sensor configured to sense the frequency variations and including;
a sensor face provided with obstacles, wherein the obstacles constitute a series of grooves formed in the sensor face for preventing movement of contamination across the sensor face, anda sensor element located between the magnet and the sensor face,wherein contamination is caused to move in a first direction across the sensor face during rotation of the rotatable element, said obstacles being arranged in a second direction that is different from the first direction to inhibit movement of contamination across the sensor face so as to minimize false frequency variations in the magnetic flux.
1 Assignment
0 Petitions
Accused Products
Abstract
A magnetic field sensor is employed to determine a rotational velocity of an element by sensing frequency variations in a magnetic flux during rotation of the element. The magnetic field sensor includes a sensor face provided with obstacles, such as a series of spaced, substantially parallel grooves arranged perpendicular to a direction in which contamination tends to move across the face during operation of the sensor. The obstacles inhibit movement of contamination across the face such that the contamination does not cause false variations in the magnetic flux which would degrade sensor signals.
-
Citations
22 Claims
-
1. A power transmission unit comprising:
-
a rotatable element for transmitting power through the power transmission unit; a magnet for creating a magnetic flux that develops frequency variations proportional to a rotational velocity of the rotatable element; and a magnetic field sensor configured to sense the frequency variations and including; a sensor face provided with obstacles, wherein the obstacles constitute a series of grooves formed in the sensor face for preventing movement of contamination across the sensor face, and a sensor element located between the magnet and the sensor face, wherein contamination is caused to move in a first direction across the sensor face during rotation of the rotatable element, said obstacles being arranged in a second direction that is different from the first direction to inhibit movement of contamination across the sensor face so as to minimize false frequency variations in the magnetic flux. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A magnetic field sensor comprising:
-
a sensor face provided with obstacles, wherein the obstacles constitute a series of grooves formed in the sensor face for preventing movement of contamination across the sensor face; a magnet; and a sensor element located between the magnet and the sensor face; wherein the magnetic field sensor is configured to sense variations in a magnetic flux; and wherein contamination is caused to move in a first direction across the sensor face, the obstacles being arranged in a second direction that is different from the first direction so as to inhibit movement of the contamination across the sensor face to minimize false variations in the magnetic flux. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
-
-
17. A method of measuring a rotational velocity of an element comprising:
-
creating a magnetic flux with a magnet; causing frequency variations in the magnetic flux proportional to the rotational velocity of the element; passing the magnetic flux through a face of a magnetic field sensor; converting the variations in the magnetic flux into an electrical signal by employing a sensor element located between the face and the magnet; and preventing movement of contamination across the face to minimize false variations in the magnetic flux which would degrade the electrical signal, wherein contamination is caused to move across the face of the magnetic field sensor in a first direction, wherein preventing movement of the contamination includes providing grooves in the face of the magnetic field sensor and wherein providing the grooves includes positioning the grooves in a second direction that is different from the first direction. - View Dependent Claims (18, 19, 20, 21, 22)
-
Specification