Proximity sensor system for industrial process transmitter

• US 20100148982A1
• Filed: 02/19/2010
• Published: 06/17/2010
• Est. Priority Date: 12/28/2006
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Hedtke, Robert C.
• Granted Patent: US 8,669,866 B2
• Time in Patent Office: Days
• US Class Current: 340/686.600
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect

Abstract

A process transmitter for measuring a process variable comprises a process sensor, transmitter circuitry, a transmitter housing, a mounting component, and a non-contact proximity sensor. The process sensor senses a process variable of a process fluid. The transmitter circuitry processes a signal from the process sensor. The transmitter housing receives the process sensor and transmitter circuitry. The transmitter mounting component is connected to the housing to isolate the sensor, the transmitter circuitry or the transmitter housing from the process fluid or an external environment. The non-contact proximity sensor system detects a spatial relationship between the transmitter housing and the transmitter mounting component.

Claims

1. A process transmitter for measuring a process variable, the process transmitter comprising:

a process sensor for sensing a process variable of a process fluid;

transmitter circuitry for processing a signal from the process sensor;

a transmitter housing for receiving the process sensor and transmitter circuitry;

a transmitter mounting component connected to the housing to isolate the sensor, the transmitter circuitry or the transmitter housing from the process fluid or an external environment; and

a non-contact proximity sensor system for detecting a spatial relationship between the transmitter housing and the transmitter mounting component.

2. The process transmitter for measuring a process variable of claim 1 wherein the proximity sensor system generates:

an active input signal between the transmitter housing and the transmitter mounting component, the input signal corresponding to the spatial relationship between the transmitter housing and the transmitter mounting component; and

an output signal corresponding to a change in the input signal due to a change in the spatial relationship.

3. The process transmitter for measuring a process variable of claim 2 wherein the proximity sensor system comprises an analog sensor.

4. The process transmitter for measuring a process variable of claim 3 wherein the proximity sensor system detects different degrees of closeness of the transmitter housing and the transmitter mounting component.

5. The process transmitter for measuring a process variable of claim 3 wherein the proximity sensor system output signal is proportional to a distance between the transmitter housing and the transmitter mounting component.

6. The process transmitter for measuring a process variable of claim 2 wherein:

the input signal comprises a magnetic field between the transmitter housing and the transmitter mounting component; and

the change in the input signal comprises a change in strength of the magnetic field due to a change in the spatial relationship.

7. The process transmitter for measuring a process variable of claim 6 wherein the proximity sensor system comprises:

a magnet connected to the transmitter mounting component to generate the magnetic field; and

a magnetometer connected to the transmitter housing opposite the magnet to detect the magnetic field.

8. The process transmitter for measuring a process variable of claim 2 wherein:

the input signal is based upon a sound wave between the transmitter housing and the transmitter mounting component; and

the change in the input signal comprises an increase in distance traveled by the sound wave due to a change in the spatial relationship.

9. The process transmitter for measuring a process variable of claim 8 wherein the proximity sensor system comprises:

an ultrasonic sensor connected to the transmitter housing to generate the sound wave; and

a reflector connected to the transmitter mounting component opposite the ultrasonic sensor to deflect the sound wave back to the ultrasonic sensor.

10. The process transmitter for measuring a process variable of claim 2 wherein:

the input signal comprises an eddy current between the transmitter housing and the transmitter mounting component; and

the change in the input signal comprises a change in an amplitude of oscillation of the eddy current due to a change in the spatial relationship.

11. The process transmitter for measuring a process variable of claim 10 wherein the proximity sensor system comprises:

permeable material connected to the transmitter mounting component; and

an inductive proximity sensor connected to the transmitter housing opposite the permeable material, the inductive proximity sensor;

an inductance coil for generating an electrostatic field positioned;

core material positioned within the inductance coil;

an oscillator for generating an eddy current in the core; and

a signal level detector for sensing a change in an amplitude of oscillation of the eddy current when position of the permeable material changes with respect to the inductive proximity sensor.

12. The process transmitter for measuring a process variable of claim 2 wherein:

the input signal comprises a light wave between the transmitter housing and the transmitter mounting component; and

the change in the input signal comprises a formation of a circuit by the light wave due to a change in the spatial relationship.

13. The process transmitter for measuring a process variable of claim 12 wherein the proximity sensor system comprises:

an optical sensor connected to the transmitter housing to generate the light wave; and

a target connected to the transmitter mounting component opposite the optical sensor to deflect the light wave back to the optical sensor.

14. The process transmitter for measuring a process variable of claim 2 wherein:

the input signal comprises an electrostatic field between the transmitter housing and the transmitter mounting component; and

the change in the input signal comprises a change in strength of the electrostatic field due to a change in the spatial relationship.

15. The process transmitter for measuring a process variable of claim 14 wherein the proximity sensor system comprises:

a first capacitor connected to the transmitter housing; and

a second capacitor connected to the transmitter mounting component opposite the first capacitor.

16. The process transmitter for measuring a process variable of claim 2 wherein the transmitter circuitry includes predetermined proximity values for comparison to the output signal generated by the proximity sensor system.

17. The process transmitter for measuring a process variable of claim 16 wherein the transmitter circuitry annunciates that the transmitter mounting component is improperly positioned or missing when the output signal does not match the predetermined proximity values.

18. The process transmitter for measuring a process variable of claim 1 wherein the transmitter mounting component comprises a sensor module.

19. The process transmitter for measuring a process variable of claim 1 wherein the transmitter mounting component comprises a process flange.

20. The process transmitter for measuring a process variable of claim 1 wherein the transmitter mounting component comprises a housing cover.