Battery assembly for wireless field device

Abstract

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

Description

Technical Field

[0001] The present invention relates generally to industrial process control and monitoring systems. More particularly, the present invention relates to wireless process field devices used in such systems. Background Art

[0002] In industrial settings, process control systems are used to monitor and control, among other things, the inventory and operation of industrial and chemical processes. Typically, systems that perform these functions use field devices distributed at key locations in the industrial process, which are connected to control circuits in the control room through process control loops. The term "field device" refers to any device that performs a function in a distributed control or process monitoring system, including all devices used for measurement, control, and monitoring of industrial processes. Typically, such field devices have field-hardened enclosures so that they can be installed in relatively harsh outdoor environments and can withstand climatic extremes in temperature, humidity, vibration, and mechanical shock.

[0003] Typically, each field device also includes communication circuitry for communicating with a process controller or other field devices or other circuits via a process control loop. In some installations, the process control loop is also used to deliver regulated current and / or voltage to the field device for powering the field device. The process control loop also carries data in analog or digital format.

[0004] In some installations, wireless technology is now used to communicate with field devices. Wireless operation simplifies the wiring and setup of field devices. Currently, wireless installations are used in which field devices include a local power source. However, due to power limitations, the functionality of such wireless field devices may be limited.

[0005] Wireless field devices may employ an intrinsically safe local power source that may be replaceable when the power source is depleted or falls below a selected threshold. When a battery replacement is required, it is desirable that the battery be easily replaceable and intrinsically safe so that it can be replaced in an explosive environment without requiring a hot work permit or removing the wireless transmitter from the explosive environment. Alternatively, some wireless field devices may use a battery that is not intrinsically safe as a power source.

[0006] Intrinsic safety is a term that refers to the ability of field devices to operate safely in potentially unstable environments. For example, the environment in which a field device operates can sometimes be so unstable that an errant spark or sufficiently high surface temperatures of an electrical component can cause the environment to ignite and produce an explosion. In order to ensure that such situations do not occur, intrinsic safety specifications have been developed. Compliance with intrinsic safety requirements helps ensure that even under fault conditions, the circuit or device itself will not ignite an unstable environment. One specification for intrinsic safety requirements is listed in APPROVAL STANDARD INTRINISICALLY SAFE APPARATUS AND ASSOCIATED APPARATUS FORUSE IN CLASS I, II AND III, DIVISION 1HAZARDOUS (CLASSIFIED) LOCATIONS, CLASS 3610, issued by Factory Mutual Research in October 1988. Adaptation to comply with additional industry standards, such as the Canadian Standards Association (CSA) and European Cenelec standards, is also considered.

[0007] Many wireless field devices are specified for use in Class 1 and Zone 0 areas. This means that explosive atmospheres may be present and very strict standards are applied to electronic equipment used in these areas. If the battery does not meet specific energy limit standards or is not properly protected from damage if dropped, it cannot be brought into a Class 1 or Zone 0 area without obtaining a hot work permit and taking steps to temporarily downgrade the area. This is a time-consuming and costly process. While there are some commercially available batteries that meet the short-circuit temperature rise requirements for intrinsic safety certification, they are easily damaged when dropped from heights as small as 2 to 3 feet because the battery positive terminal is usually sealed with a fragile glass-to-metal seal.

[0008] Another challenge in powering wireless field devices is securing the battery. Wireless field devices are often installed in very harsh industrial environments. Since the batteries in wireless field devices are expected to last up to 10 years, the long-term reliability of the connection to the battery is very important. Fretting corrosion is a phenomenon that can occur when the mating parts of a connection move very slightly relative to each other. When this happens, the protective coating on the mating interface of the connector is disturbed, resulting in the formation of corrosion that ultimately causes the contact resistance to increase and the battery can no longer power the field device. Summary of the invention

[0009] An intrinsically safe battery assembly for a field device, the intrinsically safe battery assembly comprising an intrinsically safe battery and a polymer base. In one example, the polymer base is removably connected to the intrinsically safe battery and has at least one retention mechanism configured to engage the intrinsically safe battery. In another example, the polymer structure has at least one battery ejection mechanism configured to eject the intrinsically safe battery. A field device is also provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of a wireless field device with which the embodiments described herein are particularly useful.

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

[0012] Figure 3 is a schematic exploded perspective view of a polymer base and batteries forming an intrinsically safe battery assembly according to an embodiment of the present invention.

[0013] Figure 4 is a schematic front view of a polymer base of an intrinsically safe battery assembly according to an embodiment of the present invention.

[0014] Figure 5 is a schematic top cross-sectional view of a polymer base of an intrinsically safe battery assembly according to an embodiment of the present invention.

[0015] Fig. 6A and Figure 6B is a schematic diagram showing different degrees of insertion of an intrinsically safe battery into a polymer base according to an embodiment of the present invention.

[0016] Figure 7 is a schematic diagram of an intrinsically safe battery assembly according to an embodiment of the present invention.

[0017] Figure 8 is a top cross-sectional view of an intrinsically safe battery being removed from a polymer base in accordance with an embodiment of the present invention.

[0018] Fig. 9 is a schematic 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

[0019] The 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 industrial applications and provides a reliable electrical connection that is resistant to vibration, shock, and other environmental stresses. In some embodiments, the battery assembly meets all industrial intrinsic safety requirements, thereby allowing the battery assembly to be removed and replaced in hazardous locations without downgrading the area or obtaining a hot work permit. For example, in some embodiments, the battery assembly can meet all Class 1 or Zone 0 requirements to facilitate such operations in hazardous environments. Alternatively, in some embodiments, the battery assembly may not need to be intrinsically safe.

[0020] The battery / power module is used in many wireless field devices and can be replaced many times within the life of a given field device. Due to this replacement routine, current solutions are limited in efficiency and commissioning time. The embodiments described below provide an intrinsically safe battery assembly with a more efficient battery retention and ejection mechanism. In some embodiments, both the retention component and the ejection component are set in a single polymer component. The polymer base contains a built-in snap-on retention component that slightly wraps around the power module. The embodiment also provides a rear-mounted battery ejection component that, when squeezed together, pushes forward and ejects the battery by overcoming the retention force of the retention snap. The squeeze displacement moves the battery assembly out of the retention / capture component for a clean ejection. Some embodiments also feature one or more directional guides at the base of the base to eliminate rotational and axial movement. These guides dock with corresponding grooves in the battery assembly to lock the battery assembly in place once the battery assembly is inserted. These guides also allow the battery assembly to be ejected without being restrained.

[0021] Figure 1 1 is a schematic diagram of a wireless field device with which the embodiments described herein are particularly useful. In the example shown, the 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). The field device 100 includes an enclosed weather-proofed compartment 102 that is removably connected to a sensing adapter 104. As used herein, weather-proofed refers to a covered, waterproof enclosure. Depending on the type of field element being used, the sensing adapter 104 can take a variety of forms. For example, if the field element is a process variable temperature sensor, the sensing adapter can be, for example, a temperature sensor. Figure 1102 and can be connected to a process temperature sensor body 106. The sensor body 106 can then be connected to an industrial process to measure the temperature of the process fluid. It is understood that different types of sensors (e.g., temperature, pressure, acoustic, corrosion, pH, ORP, conductivity, level, gas, etc.) will have different forms for their respective sensor bodies 106. However, in one embodiment, the sensor adapter 104 allows a variety of sensor bodies 106 to be used with the same cover 102. The cover 102 and / or the sensor body 104 can be constructed of any suitable material, as long as the cover 102 is waterproof.

[0022] Figure 2 is a block diagram of the wireless field device 100. Figure 2 As shown, the wireless field device 100 is connected to one or more sensors 150, which are in turn connected to an industrial process 152. The sensor(s) 150 may include one or more of any of the process sensors described above. The sensor(s) 150 are connected to a measurement circuit 154 of the wireless transmitter 100. The measurement circuit 154 receives an electrical output from the sensor(s) 150, which represents a process variable sensed from the industrial process 152. The measurement circuit 154 may include suitable analog-to-digital conversion circuitry to convert the analog sensor signal into a digital representation. In addition, the measurement circuit 154 may include suitable filter circuitry, amplification circuitry, and / or switching circuitry to provide compatibility with a variety of different sensor types. The measurement circuit 154 provides an output representing a process state to the controller 156.

[0023] The controller 156 can be any suitable circuit or combination of circuits that executes programmed steps to generate a process variable output based on the signal received from the measurement circuit 154. In one example, the controller 156 is a microprocessor. The controller 156 is also connected to a communication circuit 158, which can receive process variable output information from the controller 156 and provide a wireless industry standard process communication signal based on the information. Preferably, the communication circuit 158 ​​allows for two-way wireless communication using a wireless antenna 160. As schematically shown by reference numeral 162, such two-way wireless communication is typically communicated with an industrial process control system 164. Examples of suitable wireless process communication protocols are set forth in IEC 62591. However, other examples may also be considered in place of or in addition to IEC 62591.

[0024] like Figure 2 As shown, the wireless field device 100 includes an intrinsically safe battery assembly 166. The battery assembly 166 is electrically connected to other circuits of the field device 100 to provide operating power to the field device 100. Each battery assembly 166 includes a battery ( Figure 2 ) and may include intrinsically safe circuits ( Figure 2 1. 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-type cell (about 1.9 inches in length and about 1.02 inches in diameter) or a D-type cell (about 2.3 inches in length and about 1.3 inches in diameter). Other types of batteries may also be used.

[0025] The wireless field device 100 also preferably includes a battery identification circuit 167 that is connected to or is part of the controller 156. As will be described in more detail below, the embodiments disclosed herein may generally use different battery form factors (e.g., D-cell batteries and C-cell batteries) to power the wireless field device 100. Since different battery form factors generally power batteries with different energy storage, the battery identification logic system 167 allows the wireless field device 100 to determine the type of battery assembly 166 used. This allows the controller 156 to modify the operation of the wireless field device 100 based on the type of battery detected by the battery identification logic system 167. Examples of such modifications to the operation include, but are not limited to, limiting or disabling available components and / or functions, limiting performance, and limiting measurement intervals. Examples of limiting or disabling available components and / or functions may include selectively enabling / disabling a local display of the field device based on the available power from the identified type of battery assembly used. Another example includes reducing the RF power of the communication circuit 158 ​​based on the type of battery assembly used. Examples of reducing the performance of the wireless field device may include selecting a lower power mode of the controller 158, or reducing the set of functions it performs and / or when it performs those functions. Examples of limiting the measurement interval include changing the measurement interval from 10 measurements per second to one measurement per minute.

[0026] As indicated by dashed line 168, battery identification logic system 167 is electrically or mechanically connected to battery assembly 166. Through connection 168, battery identification logic system 167 is able to determine the form factor of the battery cells within battery 166. This determination may be done using electrical aspects of battery 166 or mechanical aspects of battery 166.

[0027] Figure 3is a schematic exploded perspective view of a polymer base and batteries forming an intrinsically safe battery assembly according to an embodiment of the present invention. The intrinsically safe battery assembly 200 includes an intrinsically safe battery 202 and a polymer base 204. As shown, the intrinsically safe battery 202 can be removed from the base 204 for periodic replacement when the battery is depleted. The intrinsically safe battery 202 includes a primary cell (i.e., non-rechargeable) or a secondary cell (i.e., rechargeable) 206 connected to a polymer circuit board housing 208. In some embodiments, the battery 206 is cylindrical, such as a D-cell or C-cell. Electrical contact with the battery 206 occurs in the circuit board housing 208, which may include intrinsically safe circuitry to ensure that the intrinsically safe battery assembly 202 is intrinsically safe.

[0028] As in Figure 3 As can be seen in the polymer base 204, the polymer base 204 includes a pair of semi-circular ribs 212, which are sized and shaped to support the outer diameter of the battery 206 when the battery 206 is installed in the polymer base 204. In addition, a pair of alignment features 216, 216' are shown in the polymer base 204, which cooperate with the alignment grooves or channels 218, 220, respectively, to ensure that the intrinsically safe battery assembly 202 slides into the polymer base 204 without rotation. This is particularly advantageous because the electrical connection between the connector 222 of the polymer base 204 and the intrinsically safe battery 202 is preferably a pin / socket connector, and if the intrinsically safe battery 202 is misaligned during insertion, they will not mate and may be damaged.

[0029] Figure 3 Also shown is a pair of retaining members 224, 226 which are positioned to slightly interfere with the outer diameter of the battery 206 when the battery 206 is inserted. A second pair (not shown) is located on the opposite side of the polymer base 204, but is located on the opposite side of the polymer base 204. Figure 3 204 because the view is blocked by the battery 206. The retaining features 224, 226 are positioned so that when the battery 206 is fully inserted into the polymer base 204, the interference is reduced. However, the retaining features help to apply a component force that pushes the battery 206 into the polymer base 204.

[0030] Figure 3 Also shown is a battery ejection member 228 which, when squeezed, can deflect inwardly to force the battery 206 to overcome the inward force of the retaining members 224, 226 and eject the intrinsically safe battery assembly 202 from the polymer base 204. Figure 3One battery ejection feature 228 is shown, but a similar feature is provided on the opposite side of the polymer base 204 so that the user squeezes the two ejection features 228 together (e.g., between the user's thumb and index finger) and the intrinsically safe battery assembly will be ejected into the user's open hand.

[0031] Figure 4 is a schematic front view of a polymer base of an intrinsically safe battery assembly according to an embodiment of the present invention. Figure 4 All battery holding components 224, 224', 226, 226' and all battery ejection components 228 and 228' are shown. Figure 4 Alignment features 216, 216' are shown in FIG.

[0032] Figure 5 is a schematic top cross-sectional view of a polymer base of an intrinsically safe battery assembly according to an embodiment of the present invention. Figure 5 As shown, the retaining members 226 and 226' taper and / or slope toward each other so that in the circular region they are spaced apart a distance less than the outer diameter of the battery 206. Thus, when the intrinsically safe battery 202 is inserted, the battery 206 will cause the circular region to deform outwardly.

[0033] Figure 5 Also shown is a polymer base 204 connected to an electronics compartment 230. The electronics compartment 230 houses at least one circuit board 232, which may include the above-described Figure 2 Any or all of the circuits described.

[0034] Fig. 6A and Figure 6B is a schematic diagram showing different degrees of insertion of an intrinsically safe battery into a polymer base according to an embodiment of the present invention. Fig. 6A The intrinsically safe battery 202 is shown almost completely inserted into the polymer base 204, while Figure 6B The complete intrinsically safe battery assembly 300 is shown with the intrinsically safe battery 200 and the polymer base 204 fully connected together.

[0035] Figure 7 is a schematic diagram of an intrinsically safe battery assembly according to an embodiment of the present invention. It can be seen that the outer diameter 302 of the battery 206 is greater than the distance between the battery retaining components 224 and 224', and also greater than the spacing between the battery retaining components 226 and 226'. Therefore, these components 224, 224', 226 and 226' operate to exert a force on the battery 206, which forces the battery 206 to contact the polymer base 204. In addition, Figure 7The alignment features 216 of the polymer base 204 are shown engaged within the alignment grooves / channels 218 , 220 . Figure 7 Also shown are a plurality of conductors 304 that may be connected to the sensor module to form a complete industrial transmitter.

[0036] Figure 8 FIG. 1 is a top view of an intrinsically safe battery being removed from a polymer base according to an embodiment of the present invention. Figure 8 As shown, the squeezing force (F_squeeze) is directed to the ejection members 228, 228' as shown by arrows 310, 312. This causes the ejection members 228, 228' to contact the battery 206 at the docking points 314, 316, respectively. This contact generates an ejection force (F_Rear) that is opposite to the retention force (F_front) generated by the retention members 224, 224', 226 and 226'. When the ejection force (F_Rear) exceeds the retention force (F_front), the battery 206 is ejected from the polymer base 204.

[0037] Fig. 9 is a schematic perspective view of an intrinsically safe battery being removed from a polymer base in accordance with an embodiment of the present invention. Fig. 9 The location of the compressive force 310 on the pop-up member 228 is shown.

[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.

Claims

1. An intrinsically safe battery assembly for a field device, the intrinsically safe battery assembly comprising: Intrinsically safe batteries; and A polymer base is removably connected to the intrinsically safe battery, the polymer base having at least one retention mechanism configured to engage the intrinsically safe battery.

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

3. The intrinsically safe battery assembly according to claim 2, wherein: Engagement of the plurality of retention mechanisms with the outer diameter of the intrinsically safe battery creates a retention force that urges the intrinsically safe battery into contact with the polymer base.

4. The intrinsically safe battery assembly according to claim 3, wherein: The plurality of retaining mechanisms includes four retaining mechanisms.

5. The intrinsically safe battery assembly according to claim 1, wherein: The polymer base also includes at least one battery ejection mechanism.

6. The intrinsically safe battery assembly according to 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 according to claim 6, wherein: Ejection of the intrinsically safe battery occurs when the pair of ejection mechanisms are maximally squeezed together.

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

9. The intrinsically safe battery assembly according to claim 1, wherein: The intrinsically safe battery includes at least one alignment feature and the polymer base includes a second alignment feature, and wherein the at least one alignment feature and the second alignment feature cooperate to ensure that the intrinsically safe battery is inserted into the polymer base without rotation.

10. An intrinsically safe battery assembly for a field device, the intrinsically safe battery assembly comprising: Intrinsically safe batteries; and A polymer base is removably connected to the intrinsically safe battery, the polymer base having at least one battery ejection mechanism configured to eject the intrinsically safe battery.

11. The intrinsically safe battery assembly according to 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 according to claim 11, wherein: Ejection of the intrinsically safe battery occurs when the pair of ejection mechanisms are squeezed together.

13. A field device comprising: Intrinsically safe batteries; a polymer base removably connected to the intrinsically safe battery, the polymer base having at least one retaining mechanism configured to engage the intrinsically safe battery and at least one ejection feature configured to eject the intrinsically safe battery; an electronics housing connected to the polymer base; Field device electronics are disposed within the electronics housing and are configured to measure the sensor signal and provide an output.

14. The field device according to claim 13, wherein: The at least one retention mechanism includes a plurality of retention mechanisms, and wherein the plurality of retention mechanisms are 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 creates a retention force that urges the intrinsically safe battery into contact with the polymer base.

16. The field device of claim 13, wherein: The field device electronics include wireless communications circuitry.

17. The field device of claim 13, wherein: The at least one ejection member 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 a field device, the battery assembly comprising: Battery; and A polymer base is removably connected to the battery, the polymer base having at least one retention mechanism configured to engage the battery.

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

21. The battery assembly according to claim 20, wherein: Engagement of the plurality of retention mechanisms with the outer diameter of the battery creates a retention force that urges the battery into contact with the polymer base.

22. The battery assembly according to claim 21, wherein: The plurality of retaining mechanisms includes four retaining mechanisms.

23. The battery assembly according to claim 19, and wherein: The polymer base also includes at least one battery ejection mechanism.

24. The battery assembly according to 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 according to claim 24, wherein: Ejection of the battery occurs when the pair of ejection mechanisms are maximally squeezed together.

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

27. The battery assembly according to claim 19, wherein: The battery includes at least one alignment feature and the polymer mount includes a second alignment feature, and wherein the at least one alignment feature and the second alignment feature cooperate to ensure that the battery is inserted into the polymer mount without rotation.

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