BATTERY ASSEMBLY FOR WIRELESS FIELD DEVICES

Abstract

An intrinsically-safe battery assembly for field devices, the intrinsically-safe battery assembly includes an intrinsically-safe battery and polymeric chassis. In an example, the polymeric chassis is removably coupled to the intrinsically-safe battery and has at least one retention mechanism configured to engage the intrinsically-safe battery. In another example, the polymeric structure has at least one battery ejection mechanism configured to eject the intrinsically-safe battery. A field device is also provided.

Claims

1. An intrinsically-safe battery assembly for field devices, the intrinsically-safe battery assembly comprising: an intrinsically-safe battery; and a polymeric chassis removably coupled to the intrinsically-safe battery, the polymeric structure having at least one retention mechanism configured to engage the intrinsically-safe battery.

2. The intrinsically-safe battery assembly of claim 1, wherein the at least one retention mechanism includes a plurality of retention mechanisms and wherein the plurality of retention mechanisms is configured to engage an outer diameter of the intrinsically-safe battery.

3. The intrinsically-safe battery assembly of claim 2, wherein engagement of the plurality of retention mechanisms with the outer diameter of the intrinsically-safe battery generates a retention force urging the intrinsically-safe battery into contact with the polymeric chassis.

4. The intrinsically-safe battery assembly of claim 3, wherein the plurality of retention mechanisms includes four retention mechanisms.

5. The intrinsically-safe battery assembly of claim 1, and wherein the polymeric chassis further comprises at least one battery ejector mechanism.

6. The intrinsically-safe battery assembly of claim 5, wherein the at least one battery ejection mechanism includes a pair of ejection mechanisms disposed on opposite sides of the intrinsically-safe battery.

7. The intrinsically-safe battery assembly of claim 6, wherein ejection of the intrinsically-safe battery occurs when the pair of ejection mechanisms are squeezed together sufficiently.

8. The intrinsically-safe battery assembly of claim 6, wherein ejection occurs when a force generated by the ejection mechanisms being squeezed together exceeds a retention force of the at least one retention mechanism.

9. The intrinsically-safe battery assembly of claim 1, wherein the intrinsically-safe battery includes at least one alignment feature and the polymeric chassis includes a second alignment feature and wherein the alignment features cooperate to ensure insertion of the intrinsically-safe battery into the polymeric chassis without rotation.

10. An intrinsically-safe battery assembly for field devices, the intrinsically-safe battery assembly comprising: an intrinsically-safe battery; and a polymeric chassis removably coupled to the intrinsically-safe battery, the polymeric structure having at least one battery ejection mechanism configured to eject the intrinsically-safe battery.

11. The intrinsically-safe battery assembly of claim 10, wherein the at least one battery ejection mechanism includes a pair of ejection mechanisms disposed on opposite sides of the intrinsically-safe battery.

12. The intrinsically-safe battery assembly of claim 11, wherein ejection of the intrinsically-safe battery occurs when the pair of ejection mechanisms are squeezed together.

13. A field device comprising: an intrinsically-safe battery; a polymeric chassis removably coupled to the intrinsically-safe battery, the polymeric structure having at least one retention mechanism configured to engage the intrinsically-safe battery and at least one ejection feature configured to eject the intrinsically-safe battery; an electronics housing coupled to the polymeric chassis; field device electronics disposed within the electronics housing and configured to measure a sensor signal and provide an output.

14. The field device of claim 13, wherein the at least one retention mechanism includes a plurality of retention mechanisms and wherein the plurality of retention mechanisms is configured to engage an outer diameter of the intrinsically-safe battery.

15. The field device of claim 14, wherein engagement of the plurality of retention mechanisms with the outer diameter of the intrinsically-safe battery generate a retention force urging the intrinsically-safe battery into contact with the polymeric chassis.

16. The field device of claim 13, wherein the field device electronics includes wireless communication circuitry.

17. The field device of claim 13, wherein the at least one ejection feature includes a pair of ejection mechanisms disposed on opposite sides of the intrinsically-safe battery.

18. The field device of claim 17, wherein ejection of the intrinsically-safe battery occurs when the pair of ejection mechanisms are squeezed together.

19. A battery assembly for field devices, the battery assembly comprising: a battery; and a polymeric chassis removably coupled to the battery, the polymeric structure having at least one retention mechanism configured to engage the battery.

20. The battery assembly of claim 19, wherein the at least one retention mechanism includes a plurality of retention mechanisms and wherein the plurality of retention mechanisms is configured to engage an outer diameter of the battery.

21. The battery assembly of claim 20, wherein engagement of the plurality of retention mechanisms with the outer diameter of the battery generates a retention force urging the battery into contact with the polymeric chassis.

22. The battery assembly of claim 21, wherein the plurality of retention mechanisms includes four retention mechanisms.

23. The battery assembly of claim 19, and wherein the polymeric chassis further comprises at least one battery ejector mechanism.

24. The battery assembly of claim 23, wherein the at least one battery ejection mechanism includes a pair of ejection mechanisms disposed on opposite sides of the battery.

25. The battery assembly of claim 24, wherein ejection of the battery occurs when the pair of ejection mechanisms are squeezed together sufficiently.

26. The battery assembly of claim 25, wherein ejection occurs when a force generated by the ejection mechanisms being squeezed together exceeds a retention force of the at least one retention mechanism.

27. The battery assembly of claim 19, wherein the battery includes at least one alignment feature and the polymeric chassis includes a second alignment feature and wherein the alignment features cooperate to ensure insertion of the battery into the polymeric chassis without rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a diagrammatic view of a wireless field device with which embodiments described herein are particularly useful.

[0011] FIG. 2 is a block diagram of a wireless field device.

[0012] FIG. 3 is a diagrammatic exploded perspective view of a polymeric chassis and battery that form an intrinsically-safe battery assembly in accordance with an embodiment of the present invention.

[0013] FIG. 4 is a diagrammatic front view of a polymeric chassis of an intrinsically-safe battery assembly in accordance with an embodiment of the present invention.

[0014] FIG. 5 is a diagrammatic top cross section view of a polymeric chassis of an intrinsically-safe battery assembly in accordance with an embodiment of the present invention.

[0015] FIGS. 6A and 6B are diagrammatic views showing various degrees of insertion of an intrinsically-safe battery into a polymeric chassis in accordance with an embodiment of the present invention.

[0016] FIG. 7 is a diagrammatic view of an intrinsically-safe battery assembly in accordance with an embodiment of the present invention.

[0017] FIG. 8. is a top cross section view of an intrinsically-safe battery being removed from a polymeric chassis in accordance with an embodiment of the present invention.

[0018] FIG. 9 is a diagrammatic perspective view of an intrinsically-safe battery assembly being removed from a field device in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0019] Embodiments described herein generally provide an intrinsically-safe, easily replaceable, single cell, low cost, compact battery assembly for wireless field devices. The battery assembly is suitable for an industrial application and provides a reliable electrical connection that is resistant to vibration, shock, and other environmental stresses. In some embodiments, the battery assembly meets all industry intrinsically-safe requirements allowing it to be removed and replaced in a hazardous location without the need for declassifying the area or obtaining a hot work permit. For example, in some embodiments, the battery assembly may meet all Division 1 and Zone 0 requirements to facilitate such operations in the hazardous environment. Alternatively, in some embodiments, the battery assembly may not have to be intrinsically-safe.

[0020] Batteries/power modules are used across many wireless field devices and can be replaced several times over the life of a given field device. Due to this replacement routine, current solutions are limited in terms of efficiency and commissioning time. Embodiments described below provide an intrinsically-safe battery assembly with more efficient battery retention and ejection mechanisms. In some embodiments, both retention features and ejection features are provided in a single polymeric component. The polymeric chassis contains built-in snap retention features which wrap slightly around the power module. Embodiments also provide a rear-mounted battery ejector features that, when squeezed together, push forward and eject the battery by overcoming the retaining force of the retention snaps. The squeeze displacement moves the battery assembly beyond the retention/capture features to obtain a clean ejection. Some embodiments also feature one or more directional guides at the base of the chassis to eliminate rotational and axial movement. These guides interface with corresponding grooves in the battery assembly to lock the battery assembly in place once inserted. These guides also allow the battery assembly to eject without binding.

[0021] FIG. 1 is a diagrammatic view of a wireless field device with which embodiments described herein are particularly useful. In the illustrated example, field device 100 is a wireless process variable transmitter that measures a process variable, such as temperature, and wirelessly transmits an indication of the process temperature to a remote device or control room (not shown). Field device 100 includes an enclosed, weather-proof compartment 102 that is removably coupled to sensing adapter 104. As used herein, weather-proof means a covered, watertight enclosure. Sensing adapter 104 may take various forms depending on the type of field element used. For example, if the field element is a process variable temperature sensor, sensing adapter may appear as provided in FIG. 1 and be coupled to a process temperature sensor body 106. Sensor body 106, may then be coupled to an industrial process to measure the temperature of a process fluid. As can be appreciated, different types of sensors (e.g., temperature, pressure, acoustic, corrosion, pH, ORP, conductivity, level, gas, etc.) will have different forms for their respective sensor body 106. However, in one embodiment, sensor adapter 104 allows the variety of sensor bodies 106 to be used with the same enclosure 102. Enclosure 102 and/or sensor body 104 can be constructed from any suitable material as long as enclosure 102 is watertight.

[0022] FIG. 2 is a block diagram of a wireless field device 100. As shown in FIG. 2, wireless field device 100 is coupled to one or more sensors 150, which are, in turn, coupled to an industrial process 152. Sensor(s) s 150 may include one or more of any of the process sensors described above. Sensor(s) 150 is coupled to measurement circuitry 154 of wireless transmitter 100. Measurement circuitry 154 receives an electrical output from sensor(s) 150 that represents a process variable that is sensed from an industrial process 152. Measurement circuitry 154 may include suitable analog-to-digital conversion circuitry to transform an analog sensor signal into a digital representation. Additionally, measurement circuitry 154 may include suitable filter circuitry, amplification circuitry, and/or switching circuitry in order to provide compatibility for a variety of different sensor types. Measurement circuitry 154 provides an output representative of the process state to controller 156.

[0023] Controller 156 may be any suitable circuitry or combination of circuitry that executes programmatic steps to generate a process variable output based upon signals received from measurement circuitry 154. In one example, controller 156 is a microprocessor. Controller 156 is also coupled to communication circuitry 158 which can receive the process variable output information from controller 156 and provide wireless industry standard process communication signals based thereon. Preferably, communication circuitry 158 allows bidirectional wireless communication utilizing wireless antenna 160. As shown diagrammatically at reference numeral 162, this bidirectional wireless communication generally communicates with the industrial process control system 164. An example of a suitable wireless process communication protocol is set forth in IEC 62591. However, other examples instead of or in addition to IEC 62591 are also contemplated.

[0024] As shown in FIG. 2, wireless field device 100 includes an intrinsically-safe battery assembly 166. Battery assembly 166 is electrically coupled to other circuitry of field device 100 to supply operating power to field device 100. Each battery assembly 166 includes a battery (not shown in FIG. 2) and may include intrinsic safety circuitry (not shown in FIG. 2). The battery may be a primary, non-rechargeable battery or it may be a rechargeable battery. In one embodiment, the battery is a lithium ion, non-rechargeable battery. The battery may be in the form of a C-cell battery (length of about 1.9 inches and diameter of about of 1.02 inches) or a D-cell battery (length of about 2.3 inches and diameter of about of 1.3 inches). Other battery types may also be used.

[0025] Wireless field device 100 also preferably includes battery identification circuitry 167 that is coupled to, or part of, controller 156. As will be described in greater detail below, embodiments disclosed herein may generally use different battery form factors (e.g., D-cell and C-cell) for powering wireless field device 100. Since different battery form factors generally provide batteries with different energy storage, battery identification logic 167 allows wireless field device 100 to determine the type of battery assembly 166 used. This allows controller 156 to modify operation of wireless field device 100 based on the type of battery detected by battery identification logic 167. Examples of such modification of operation include, without limitation, limiting or inhibiting available features and/or functions, limiting performance, and limiting a measurement interval. An example of limiting or inhibiting available features and or functions can include selectively enabling/disabling a local display of the field device based on available power from the identified type of battery assembly used. Another example includes reducing radio-frequency power of the communication circuitry 158 based on the type of battery assembly used. An example of reducing performance of the wireless field device may include selecting a lower power mode of controller 158 or reducing the set of functions it performs and/or when it performs them. An example of limiting a measurement interval includes changing the measurement interval from 10 times per second to one measurement per minute.

[0026] Battery identification logic 167 is coupled, either electrically or mechanically, to battery assembly 166, as indicated by dashed line 168. By virtue of coupling 168, battery identification logic 167 is able to determine a form factor of the battery cell within battery 166. This determination may be done using an electrical aspect of battery 166 or a mechanical aspect of battery 166.

[0027] FIG. 3 is a diagrammatic exploded perspective view of a polymeric chassis and battery that form an intrinsically-safe battery assembly in accordance with an embodiment of the present invention. Intrinsically-safe battery assembly 200 includes intrinsically-safe battery 202 and polymeric chassis 204. As shown, intrinsically-safe battery 202 is removeable from chassis 204 for periodic replacement as the battery becomes depleted. Intrinsically-safe battery 202 includes a primary cell (i.e., non-rechargeable) or secondary cell (i.e., rechargeable) battery 206 coupled to a polymeric circuit board housing 208. In some embodiments, battery 206 is cylindrical, such as a D-cell or C-cell battery. Electrical contact with battery 206 occurs in circuit board housing 208, which may include intrinsic-safety circuitry to ensure that intrinsically-safe battery assembly 202 is intrinsically-safe.

[0028] As can be seen in FIG. 3, polymeric chassis 204 includes a pair of semi-circular ribs 212 that are sized and shaped to support an external diameter of battery 206 when battery 206 is mounted within polymeric chassis 204. Additionally, a pair of alignment features 216, 216 are shown in polymeric chassis 204 that cooperate with alignment grooves or channels 218, 220, respectively, to ensure that intrinsically-safe battery assembly 202 slides into polymeric chassis 204 without rotating. This is particularly advantageous as electrical connection between connectors 222 of polymeric chassis 204 and intrinsically-safe battery 202 are preferably pin/receptacle connectors and they would not mate and could potentially be damaged if intrinsically-safe battery 202 were misaligned during insertion.

[0029] FIG. 3 also shows a pair of retention features 224, 226 that are positioned to slightly interfere with the outer diameter of battery 206 as battery 206 is inserted. A second pair (not shown) is located on an opposite side of polymeric chassis 204 but is not visible in FIG. 3 because the view is blocked by battery 206. Retention features 224, 226 are located such that when battery 206 is fully inserted into polymeric chassis 204, the interference is reduced. However, retention features help to apply a force component that urges battery 206 into polymeric chassis 204.

[0030] FIG. 3 also shows a battery ejection feature 228 that is inwardly deflectable when squeezed to force battery 206 to overcome the inward force of the retention features 224, 226 and eject intrinsically-safe battery assembly 202 from polymeric chassis 204. While FIG. 3 shows one battery ejection feature 228 a similar feature is disposed on an opposite side of polymeric chassis 204 such that a user will squeeze the two ejection features 228 together (for example between a user's thumb and forefinger) and then the intrinsically-safe battery assembly will be ejected into the user's open hand.

[0031] FIG. 4 is a diagrammatic front view of a polymeric chassis of an intrinsically-safe battery assembly in accordance with an embodiment of the present invention. FIG. 4 shows all battery retention features 224, 224, 226, 226 as well as all battery ejection features 228 and 228. Additionally, both alignment features 216, 216 are shown in FIG. 4.

[0032] FIG. 5 is a diagrammatic top cross section view of a polymeric chassis of an intrinsically-safe battery assembly in accordance with an embodiment of the present invention. As shown in FIG. 5, retention features 226 and 226 taper and/or tilt toward one another such that in the circled regions, they are spaced apart by a distance that is less than the outer diameter of battery 206. Thus, battery 206 will cause the circled regions to deform outwardly as the intrinsically-safe battery 202 is inserted.

[0033] FIG. 5 also shows polymeric chassis 204 coupled to electronics compartment 230. Electronics compartment 230 houses at least one circuit board 232, which may contain any or all of the circuitry described above with respect to FIG. 2.

[0034] FIGS. 6A and 6B are diagrammatic views showing various degrees of insertion of an intrinsically-safe battery into polymeric chassis in accordance with an embodiment of the present invention. FIG. 6A show intrinsically-safe battery 202 almost fully inserted into polymeric chassis 204 while FIG. 6B shows the completed intrinsically-safe battery assembly 300 formed of intrinsically-safe battery 202 and polymeric chassis 204 fully coupled together.

[0035] FIG. 7 is a diagrammatic view of an intrinsically-safe battery assembly in accordance with an embodiment of the present invention. As can be seen, battery 206 has an outer diameter 302 that is greater than the distance between battery retention features 224 and 224 as well as greater than the distance between battery retention features 226 and 226. As such features 224, 224, 226, and 226 operate to exert a force on battery 206 that urges battery 206 into contact with polymeric chassis 204. Additionally, FIG. 7 shows alignment features 216 of polymeric chassis 204 engaged within alignment grooves/channels 218, 220. FIG. 7 also shows a number of conductors 304 that are coupleable to a sensor module to form a completed industrial transmitter.

[0036] FIG. 8. is a top view of an intrinsically-safe battery being removed from a polymeric chassis in accordance with an embodiment of the present invention. As shown in FIG. 8, a squeeze force (F_Squeeze) is directed as shown at arrows 310, 312 on ejection features 228, 228. This causes ejection features 228, 228 to contact batter 206 at interfaces 314, 316, respectively. This contact generates an ejection force (F_Rear) that opposes the retention force (F_front) generated by retention features 224, 224, 226, and 226. When the ejection force (F_Rear) exceeds the retention force (F_front), battery 206 is ejected from polymeric chassis 204.

[0037] FIG. 9 is a diagrammatic perspective view of an intrinsically-safe battery being removed from a polymeric chassis in accordance with an embodiment of the present invention. FIG. 9 shows the location of squeeze force 310 on ejection feature 228.

[0038] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.