ROTATION DETECTOR

• US 20110084691A1
• Filed: 09/15/2010
• Published: 04/14/2011
• Est. Priority Date: 10/13/2009
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho
• Original Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho
• Inventors: TAKEUCHI, Shuichi
• Granted Patent: US 8,436,606 B2
• Time in Patent Office: Days
• US Class Current: 324/207.25
• CPC Class Codes: G01D 5/24476 Signal processing G01D5/2448 - G01D5/24495 take precedence
• CPC Class Codes: G01D 5/2448 Correction of gain, threshold, offset or phase control

Abstract

A rotation detector includes a first distance sensor disposed to face a rotating body with a gear portion formed non-parallel to a rotation axis for continuously measuring a distance from the gear portion during rotation of the rotating body, a second distance sensor disposed at a position different from the first distance sensor in a direction of the rotation axis for continuously measuring a distance from the gear portion during rotation of the rotating body, and an axis shift detecting portion for detecting an axis shift of the rotation axis based on a variation in the distance measured by at least one of the first and second distance sensors.

Claims

1. A rotation detector, comprising:

a first distance sensor disposed to face a rotating body with a gear portion formed non-parallel to a rotation axis for continuously measuring a distance from the gear portion during rotation of the rotating body;

a second distance sensor disposed at a position different from the first distance sensor in a direction of the rotation axis for continuously measuring a distance from the gear portion during rotation of the rotating body; and

an axis shift detecting portion for detecting an axis shift of the rotation axis based on a variation in the distance measured by at least one of the first and second distance sensors.

2. The rotation detector according to claim 1, wherein the axis shift detecting portion detects the shift of the rotation axis based on an increase, a decrease or a combination thereof in the distance measured by at least one of the first and second distance sensors.

3. The rotation detector according to claim 1, wherein the axis shift detecting portion detects the shift of the rotation axis based on a difference of timing to measure the distance that is measured by at least one of the first and second distance sensors.

4. The rotation detector according to claim 1, further comprising:

a rotation detecting portion for correcting the distance measured by the first or second distance sensor based on the shift of the rotation axis detected by the axis shift detecting portion and detecting the number of revolutions of the gear portion.

5. The rotation detector according to claim 1, further comprising:

an abnormal condition detecting portion for detecting an abnormal condition of the rotating body based on the shift of the rotation axis detected by the axis shift detecting portion.

6. The rotation detector according to claim 1, wherein the first and second distance sensors are disposed at positions to provide the same argument on an x-y plane centered around the rotation axis.

7. The rotation detector according to claim 1, wherein the first and second distance sensors are disposed at positions to provide different arguments on an x-y plane centered around the rotation axis.

8. The rotation detector according to claim 6, wherein the first and second distance sensors are disposed directly above end portions of the gear portion in the direction of the rotation axis.

9. The rotation detector according to claim 7, wherein the first and second distance sensors are disposed directly above portions other than above the end portions of the gear portion in the direction of the rotation axis.

10. The rotation detector according to claim 1, wherein the first and second distance sensors comprise a magnetic or optical distance sensor.