Industrial process field device with improved battery assembly

• US 8,031,453 B2
• Filed: 05/02/2008
• Issued: 10/04/2011
• Est. Priority Date: 05/02/2007
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Johnson, James A., Nelson, Richard L.
• Primary Examiner(s): Nguyen; Danny
• Application Number:
  US12/114,099
• Publication Number:
  US 20080274772A1
• Time in Patent Office: 1,250 Days
• Field of Search: 361 937- 939, 361/92
• US Class Current: 361/93.9
• CPC Class Codes: G05B 2219/24136 Monitor load state of battery
• CPC Class Codes: G05B 2219/25428 Field device
• CPC Class Codes: H01M 2200/00 Safety devices for primary or secondary batteries
• CPC Class Codes: H01M 2200/103 Fuse
• CPC Class Codes: H01M 50/213 adapted for cells having curved cross-section, e.g. round or elliptic H01M50/209, H01M50/216 take precedence
• CPC Class Codes: H05K 7/1462 for programmable logic controllers [PLC] for automation or industrial process control
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An industrial process field device is provided. The device includes wireless process field device electronics disposed within the industrial process field device and at least one battery cell disposed within the industrial process field device and operably coupled to the wireless process field device electronics. A circuit is provided that senses an electrical characteristic related to the at least one cell and provides an output to a switch to decouple the at least one cell from the industrial process field device electronics in response to certain conditions. Such conditions include too much current flowing from the at least one cell; the voltage of the at least one cell being too low; or a short circuit being generated or otherwise observed.

Claims

1. An industrial process field device, comprising:

wireless process field device electronics disposed within the industrial process field device;

at least one battery cell disposed within the industrial process field device and operably coupled to the wireless process field device electronics;

a fuse electrically interposed between the wireless process field device electronics and the at least one battery cell, the fuse having a rated fuse current value;

a circuit configured to measure current through the fuse and provide an output if the current exceeds a threshold below the rated fuse current value; and

a switch coupled to the output of the circuit to decouple the at least one battery cell from the wireless process field device when the current exceeds the threshold.

2. The industrial process field device of claim 1, wherein at least a portion of the circuit is designed to meet an intrinsic safety requirement.

3. The industrial process field device of claim 2, wherein the circuit measures a voltage drop across the fuse.

4. The industrial process field device of claim 2, and further comprising a sense resistor disposed in series between the fuse and the circuit, and wherein the circuit measures a voltage from the sense resistor that is proportional to the current.

5. The industrial process field device of claim 1, wherein the circuit further includes an operational amplifier operably coupled to the fuse, a voltage reference coupled to operational amplifier, and a switch coupled the output of the operational amplifier.

6. The industrial process field device of claim 5, wherein the voltage reference has an output that provides a reference voltage to the operational amplifier.

7. The industrial process field device of claim 5, wherein the voltage reference comprises a resistor divider network.

8. The industrial process field device of claim 1, and further comprising low-voltage cutoff circuitry to decouple the at least one battery cell from the wireless process field device electronics when the battery voltage is below a threshold.

9. The industrial process field device of claim 8, and further comprising a transistor having a first leg coupled to a first side of the fuse, a second leg coupled to an opposite side of the fuse, and a third leg coupled to a switch interposed between the at least one cell and the wireless process field device electronics.

10. The industrial process field device of claim 1, and further comprising a transistor having a first leg coupled to a first side of the fuse, a second leg coupled to an opposite side of the fuse, and a third leg coupled to a switch interposed between the at least one cell and the wireless process field device electronics.

11. An industrial process field device, comprising:

wireless process field device electronics disposed within the industrial process field device;

at least one battery cell disposed within the industrial process field device and operably coupled to the wireless process field device electronics;

a circuit configured to measure voltage of the at least one cell and provide an output if the voltage falls below a threshold, wherein the circuit includes an operational amplifier for comparing a plurality of inputs, and generating an output based on the comparison, wherein a first input is coupled to the voltage of the at least one battery cell, the second input is coupled to a reference voltage; and

a switch coupled to the output of the operational amplifier to decouple the at least one battery cell from the wireless process field device electronics when the voltage falls below the threshold.

12. The industrial process field device of claim 11, wherein at least a portion of the circuit is designed to meet an intrinsic safety requirement.

13. An industrial process field device, comprising:

wireless process field device electronics disposed within the industrial process field device;

at least one battery cell disposed within the industrial process field device and operably coupled to the wireless process field device electronics;

a circuit configured to measure voltage of the at least one cell and provide an output if the voltage falls below a threshold; and

a fuse electrically interposed between the at least one battery cell and the wireless process field device electronics, and a transistor having a first leg coupled to a first side of the fuse, a second leg coupled to an opposite side of the fuse, and a third leg coupled to the switch.