Fluid gauges comprising multiple differential pressure sensors

Patent metadata

Field	Value
Publication number	US-10466045-B2
Application number	US-201313753754-A
Country	US
Kind code	B2
Filing date	Jan 30, 2013
Priority date	Jan 31, 2012
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

The subject fluid gauges measure actual position of a workpiece relative to a target position. A gauge body that is positionable relative to the workpiece and that includes multiple differential-pressure (DP) sensors has a measurement channel and respective reference channels. Each DP sensor measures, over a respective individual dynamic pressure range, a differential pressure established by a respective fluid flow in the measurement channel relative to a fluid flow in a respective reference channel. The dynamic pressure ranges of the DP sensors substantially overlap each other. A controller is connected to and monitors the DP sensors. The controller is configured to select, for obtaining a differential pressure indicative of the position of the workpiece, a DP sensor sensing the smallest magnitude of DP.

First claim

What is claimed is:

1. A fluid gauge for measuring actual position of an object relative to a target position, comprising:
a gauge body that is positionable relative to the object and that includes a measurement fluid passageway and multiple differential-pressure sensors which measure a difference between pressure of fluid in the measurement fluid passageway and pressure of fluid in a respective reference fluid passageways and which produce respective differential-pressure signals, the differential-pressure sensors measuring respective differential pressures established by respective fluid flows in the measurement fluid passageway relative to fluid flow in the respective reference fluid passageways having respective reference outlets situated at different gaps with respect to respective reference planes, each of the respective reference fluid passageways coupled to an associated flow restrictor, wherein each flow restrictor is associated with a different flow restriction and each of the respective reference fluid passageways are independent of each other; and
a controller connected to and monitoring the differential-pressure sensors, the controller being configured to determine respective position estimates based on the differential-pressure signals, and to determine a measured position of the object based on determined weighted averages of the position estimates.

2. A fluid gauge for measuring an axial position of a workpiece, comprising:
a fluid source coupled to supply a fluid;
a measurement fluid passageway, one end of the measurement fluid passageway connected to the fluid source and another end of the measurement fluid passageway having a measurement outlet adjacent to the workpiece;
a first reference fluid passageway, one end of the first reference fluid passageway connected to the fluid source and another end of the first reference fluid passageway having a first reference outlet situated at a first interval with respect to a first reference plane so that fluid from the fluid source flows to the first reference plane;
a second reference fluid passageway, independent of the first fluid passageway, one end of the second reference fluid passageway connected to the fluid source and another end of the second reference fluid passageway having a second reference outlet situated at a second interval which differs from the first interval with respect to a second reference plane so that fluid from the fluid source flows to the second reference plane;
a first differential-pressure sensor that detects a differential pressure between fluid passing through the measurement fluid passageway and fluid passing through the first reference fluid passageway;
a second differential-pressure sensor that detects a differential pressure between fluid passing through the measurement fluid passageway and fluid passing through the second reference fluid passageway; and
a controller configured to determine the axial position of the workpiece by using at least one of a first output from the first differential-pressure sensor and a second output from the second differential-pressure sensor.

3. The fluid gauge of claim 2 , wherein the controller is configured to select one of the first output and the second output.

4. The fluid gauge of claim 2 , wherein the first differential-pressure sensor has a first differential-pressure measurement range and the second differential-pressure sensor has a second differential-pressure measurement range partially overlapping the first differential-pressure measurement range.

5. The fluid gauge of claim 3 , wherein the first output from the first differential-pressure sensor has a first magnitude and the second output from the second differential-pressure sensor has a second magnitude, and the controller determines the axial position based on the smaller of the first magnitude and the second magnitude.

6. The fluid gauge of claim 3 , wherein the controller is configured to determine the axial position by using either the first output from the first differential-pressure sensor or the second output from the second differential-pressure sensor, whichever is closest to zero.

7. The fluid gauge of claim 4 , wherein the controller is configured to determine the axial position based on whichever of the first output from the first differential-pressure sensor or the second output from the second differential-pressure sensor is closer zero to reduce an axial position measurement error.

8. The fluid gauge of claim 3 , wherein the controller is configured to determine the axial position based on whichever of the first output from the first differential-pressure sensor or the second output from the second differential-pressure sensor is closer to zero to reduce an axial position measurement error.

9. The fluid gauge of claim 2 , wherein the measurement outlet is provided at gap with respect to the workpiece.

10. A fluid gauge for measuring axial position of a workpiece, comprising:
a fluid source coupled to supply a fluid;
a measurement fluid passageway, one end of the measurement fluid passageway connected to the fluid source, and another end of the measurement fluid passageway having a measurement outlet adjacent to the workpiece;
a first reference fluid passageway, one end of the first reference fluid passageway connected to the fluid source, and another end of the first reference fluid passageway connected to a first flow restrictor associated with a first flow restriction so that fluid flows from the fluid source to an output of the first flow restrictor;
a second reference fluid passageway, independent of the first fluid passageway, one end of the second reference fluid passageway connected to the fluid source, and another end of the second reference fluid passageway connected to a second flow restrictor associated with a second flow restriction that is different from the first flow restriction so that fluid flows from the fluid source to an output of the second flow restrictor;
a first differential-pressure sensor coupled to detect a differential pressure between the measurement fluid passageway and the first reference fluid passageway;
a second differential-pressure sensor coupled to detect a differential pressure between the measurement fluid passageway and the second reference fluid passageway; and
a controller configured to determine an axial position of the workpiece based on at least one of a first output from the first differential-pressure sensor and a second output from the second differential-pressure sensor.

11. The fluid gauge of claim 10 , wherein the controller is configured to select one of the first output and the second output.

12. The fluid gauge of claim 10 , wherein the first differential-pressure sensor has a first differential-pressure measurement range and the second differential-pressure sensor has a second differential-pressure measurement range which partially overlaps the first differential-pressure measurement range.

13. The fluid gauge of claim 12 , wherein the first output has a first magnitude and the second output has a second magnitude, and the controller is configured to determine the axial position based on the smaller of the first magnitude and the second magnitude.

14. The fluid gauge of claim 12 , wherein the controller is configured to determine the axial position based on whichever of the first output or the second output is associated with a differential pressure value that is closer to zero.

15. The fluid gauge of claim 12 , wherein the controller is configured to determine the axial position based on whichever of the first output and the second output is associated

Assignees

• Nikon Corp

Inventors

• Sogard Michael

Classifications

• G01B13/12 Primary

  for measuring distance or clearance between spaced objects or spaced apertures (G01B13/18 takes precedence) · CPC title