EXPLOSION PROOF FEED-THROUGH

Abstract

An explosion proof electronics enclosure (200), is provided having a first compartment (206) and a second compartment (207) defined by a body (205). A septum (208) is between the first compartment (206) and the second compartment (207). A first aperture (209) in the septum (208) connects the first compartment (206) and the second compartment (207). A cavity (225) communicates with the first aperture (209), wherein the cavity (225) comprises an undercut taper (226). A potting (230) in the cavity (225) conforms to the cavity (225) shape, and forms a substantially explosion-proof interface between the first compartment (206) and the second compartment (207).

Claims

1. An explosion proof electronics enclosure (200), comprising: a first compartment (206) defined by a body (205); a second compartment (207) defined by the body (205); a septum (208) between the first compartment (206) and the second compartment (207); a first aperture (209) with the septum (208) that connects the first compartment (206) and the second compartment (207); a cavity (225) in communication with the first aperture (209), wherein the cavity (225) comprises an undercut taper (226); and a potting (230) with the cavity (225) that conforms to the cavity (225) shape, and forms a substantially explosion-proof interface between the first compartment (206) and the second compartment (207).

2. The explosion proof electronics enclosure (200) of claim 1, comprising: a feed-through element (210) comprising a first interface region (211) and a second interface region (212), wherein one or more conductors (217) extend between the first interface region (211) and the second interface region (212), and wherein the first interface region (211) resides in the first compartment (206), and the second interface region (212) resides in the second compartment (207); and wherein the potting (230) retains the feed-through element (210) in the cavity (225) and the first aperture (209).

3. The explosion proof electronics enclosure (200) of claim 2, wherein the feed-through element (210) comprises a printed circuit board.

4. The explosion proof electronics enclosure (200) of claim 1, wherein a cross section of the cavity (225) comprises a dovetail shape.

5. The explosion proof electronics enclosure (200) of claim 1, wherein a cross section of the cavity (225) comprises a frustoconical shape.

6. The explosion proof electronics enclosure (200) of claim 1, comprising a support plate (240) disposed in the cavity (225), wherein the support plate (240) comprises a second aperture (241) therein, and wherein the support plate (240) aids retaining the potting (230) during an explosion.

7. The explosion proof electronics enclosure (200) of claim 6, wherein the support plate (240) is configured to maintain a feed-through element (210) in a predetermined position in the first aperture (209) and cavity (225).

8. The explosion proof electronics enclosure (200) of claim 1, wherein a cross section of the undercut comprises an undercut angle between 15° and 25°.

9. A method of forming an explosion proof electronics enclosure (200), with the method comprising: providing a feed-through body (205) comprising a first compartment (206) and a second compartment (207); separating the first compartment (206) and the second compartment (207) with a septum (208); placing a first aperture (209) in the septum (208) that connects the first compartment (206) and the second compartment (207); providing a cavity (225) in communication with the first aperture (209), wherein the cavity (225) comprises an undercut taper (226), and wherein a maximally undercut portion of the undercut taper (226) is proximate the first compartment (206); and placing potting (230) in the cavity (225), such that the potting (230) conforms to the cavity (225) shape, and forms a substantially explosion-proof interface between the first compartment (206) and the second compartment (207).

10. The method of forming an explosion proof electronics enclosure (200) of claim 9, comprising: inserting a feed-through element (210) through the first aperture (209) and cavity (225), wherein the feed-through element (210) comprises a first interface region (211) and a second interface region (212), wherein one or more conductors (217) extend between the first interface region (211) and the second interface region (212), and wherein the first interface region (211) resides in the first compartment (206), and the second interface region (212) resides in the second compartment (207); and retaining the feed-through element (210) in the cavity (225) and the first aperture (209) with the potting (230).

11. The method of forming an explosion proof electronics enclosure (200) of claim 9, comprising shaping a cross section of the cavity (225) to comprise a dovetail shape.

12. The method of forming an explosion proof electronics enclosure (200) of claim 9, comprising shaping a cross section of the cavity (225) to comprise a frustoconical shape.

13. The method of forming an explosion proof electronics enclosure (200) of claim 9, comprising: forming a second aperture (241) in a support plate (240); and placing the support plate (240) in the cavity (225), wherein the support plate (240) aids retaining the potting (230) during an explosion.

14. The method of forming an explosion proof electronics enclosure (200) of claim 13, comprising the steps of: installing a feed-through element (210) through the second aperture (241) of the support plate (240); and maintaining a feed-through element (210) in a predetermined position in the first aperture (209) and cavity (225) with the support plate (240).

15. The method of forming an explosion proof electronics enclosure (200) of claim 14, wherein the feed-through element (210) is installed through the second compartment (207).

Description

DESCRIPTION OF THE DRAWINGS

[0033] The same reference number represents the same element on all drawings. The drawings are not necessarily to scale.

[0034] FIG. 1 shows a vibratory flowmeter according to an embodiment of the invention;

[0035] FIG. 2 illustrates an embodiment of an explosion proof electronics enclosure mounted on a portion of a flowmeter;

[0036] FIG. 3 is a cutaway isometric view of the explosion proof electronics enclosure of FIG. 2; and

[0037] FIG. 4 illustrates a magnified cross-sectional view of the explosion proof electronics enclosure of FIG. 3.

DETAILED DESCRIPTION

[0038] FIGS. 1-4 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

[0039] FIG. 1 shows a vibratory flowmeter 5 according to the invention. The explosion proof feedthrough described herein is contemplated for use with such a vibratory flowmeter 5. However, this is merely an example of an application for the explosion proof feedthrough, and is in no way limiting, as the explosion proof feedthrough may be utilized with any appropriate device. The vibratory flowmeter 5 comprises a flowmeter assembly 10 and meter electronics 20. The meter electronics 20 is connected to the meter assembly 10 via leads 100 and is configured to provide measurements of one or more of a density, mass flow rate, volume flow rate, totalized mass flow, temperature, or other measurements or information over a communication path 26. It should be apparent to those skilled in the art that the vibratory flowmeter 5 can comprise any manner of vibratory flowmeter, regardless of the number of drivers, pick-off sensors, flow conduits, or the operating mode of vibration. In some embodiments, the vibratory flowmeter 5 can comprise a Coriolis mass flowmeter. In addition, it should be recognized that the vibratory flowmeter 5 can alternatively comprise a vibratory densitometer.

[0040] The flowmeter assembly 10 includes a pair of flanges 101a and 101b, manifolds 102a and 102b, a driver 104, pick-off sensors 105a and 105b, and flow conduits 103A and 103B. The driver 104 and the pick-off sensors 105a and 105b are connected to the flow conduits 103A and 103B.

[0041] The flanges 101a and 101b are affixed to the manifolds 102a and 102b. The manifolds 102a and 102b can be affixed to opposite ends of a spacer 106 in some embodiments. The spacer 106 maintains the spacing between the manifolds 102a and 102b in order to prevent pipeline forces from being transmitted to flow conduits 103A and 103B. When the flowmeter assembly 10 is inserted into a pipeline (not shown) which carries the flow fluid being measured, the flow fluid enters the flowmeter assembly 10 through the flange 101a, passes through the inlet manifold 102a where the total amount of flow fluid is directed to enter the flow conduits 103A and 103B, flows through the flow conduits 103A and 103B and back into the outlet manifold 102b, where it exits the meter assembly 10 through the flange 101b.

[0042] The flow fluid can comprise a liquid. The flow fluid can comprise a gas. The flow fluid can comprise a multi-phase fluid, such as a liquid including entrained gases and/or entrained solids.

[0043] The flow conduits 103A and 103B are selected and appropriately mounted to the inlet manifold 102a and to the outlet manifold 102b so as to have substantially the same mass distribution, moments of inertia, and elastic modulus about the bending axes Wa—Wa and Wb—Wb respectively. The flow conduits 103A and 103B extend outwardly from the manifolds 102a and 102b in an essentially parallel fashion.

[0044] The flow conduits 103A and 103B are driven by the driver 104 in opposite directions about the respective bending axes Wa and Wb and at what is termed the first out of phase bending mode of the vibratory flowmeter 5. The driver 104 may comprise one of many well known arrangements, such as a magnet mounted to the flow conduit 103A and an opposing coil mounted to flow conduit 103B. An alternating current is passed through the opposing coil to cause both conduits to oscillate. A suitable drive signal is applied by the meter electronics 20 to the driver 104 via the lead 110. Other driver devices are contemplated and are within the scope of the description and claims.

[0045] The meter electronics 20 receives sensor signals on the leads 111a and 111b, respectively. The meter electronics 20 produces a drive signal on the lead 110 which causes the driver 104 to oscillate the flow conduits 103A and 103B. Other sensor devices are contemplated and are within the scope of the description and claims.

[0046] The meter electronics 20 processes the left and right velocity signals from the pick-off sensors 105a and 105b in order to compute a flow rate, among other things. The communication path 26 provides an input and an output means that allows the meter electronics 20 to interface with an operator or with other electronic systems. The description of FIG. 1 is provided merely as an example of the operation of a Coriolis flowmeter and is not intended to limit the teaching of the present invention.

[0047] The meter electronics 20 in one embodiment is configured to vibrate the flowtubes 103A and 103B. The vibration is performed by the driver 104. The meter electronics 20 further receives resulting vibrational signals from the pickoff sensors 105a and 105b. The vibrational signals comprise vibrational responses of the flowtubes 103A and 103B. The meter electronics 20 processes the vibrational responses and determines a response frequency and/or phase difference. The meter electronics 20 processes the vibrational response and determines one or more flow measurements, including a mass flow rate and/or density of the flow fluid. Other vibrational response characteristics and/or flow measurements are contemplated and are within the scope of the description and claims.

[0048] In one embodiment, the flowtubes 103A and 103B comprise substantially U-shaped flowtubes, as shown. Alternatively, in other embodiments, the flowtubes can comprise substantially straight flowtubes or can comprise one or more flowtubes of curved shapes other than U-shaped flowtubes. Additional flowmeter shapes and/or configurations can be used and are within the scope of the description and claims.

[0049] FIG. 2. is a view of an explosion proof electronics enclosure 200 according to an embodiment of the invention. The explosion proof electronics enclosure 200 is installed on a flowmeter 5 for illustrative purposes only, as the explosion proof electronics enclosure 200 may be utilized in any application where an explosion proof electronics enclosure 200 is contemplated. The explosion proof electronics enclosure 200 comprises a first access point 201 and a second access point 202. These access points 201, 202 provide means to access the interior spaces of the explosion proof electronics enclosure 200. In an embodiment, the access points 201, 202 may comprise cap members 203 that are secured to the body 205 of the explosion proof electronics enclosure 200. In an embodiment, at least one of the cap members may be transparent so that interior electronics and/or a display may be visible to a user.

[0050] FIG. 3 is an exploded view of the explosion proof electronics enclosure 200 according to an embodiment of the invention. FIG. 4 is a magnified view of a portion of FIG. 3. The explosion proof electronics enclosure 200 in this embodiment includes a feed-through element 210. In an embodiment, the feed-through element 210 comprises a substantially planar shape, a first interface region 211, and a second interface region 212, wherein one or more conductors 217 extend between the first interface region 211 and the second interface region 212.

[0051] The body 205 of the explosion proof electronics enclosure 200 defines a first compartment 206 and a second compartment 207. In an embodiment, meter electronics 20 or other types of electronics are disposed in the first compartment 206, while terminals and/or interfaces are disposed in the second compartment 207. A septum 208 separates the first compartment 206 and a second compartment 207.

[0052] A first aperture 209 between the first interface region 211 and the second interface region 212 allows communication between the first compartment 206 and a second compartment 207. The aperture 209 may comprise an aperture in a barrier, wall, the septum, or any other partition between the first compartment 206 and the second compartment 207.

[0053] The interface regions 211, 212 may include, define, or receive an electrical connector or other electrical component.

[0054] The first interface region 211 of the feed-through element 210 extends at least partially to the first compartment 206 of the explosion proof electronics enclosure 200. The second interface region 212 of the feed-through element 210 extends at least partially to the second compartment 207 of the explosion proof electronics enclosure 200.

[0055] The feed-through element 210 may comprise a substantially planar shape in some embodiments. However, the feed-through element 210 may be formed in any desired or needed shape. In some embodiments, the second interface region 212 may be substantially opposite the first interface region 211. However, this is not required and the second interface region 212 may be at any position/orientation with respect to the first interface region 211.

[0056] The feed-through element 210 includes one or more conductors 217 extending from the first interface region 211 to the second interface region 212. The one or more conductors 217 may comprise external conductors formed on an outer surface of the feed-through element 210. Alternatively, the one or more conductors 217 may comprise one or more internal conductors formed partially or completely within the feed-through element 210. The one or more conductors 217 may conduct electricity and/or electrical signals between the first interface region 211 and the second interface region 212.

[0057] The feed-through element 210 may comprise an electrical insulator material. The feed-through element 210 may comprise a non-flammable or flame or heat-resistant material. In some embodiments, the feed-through element 210 may comprise a printed circuit board (PCB). The one or more conductors 217 may be formed on outside surfaces of the feed-through element 210 or may be located partially or completely inside the feed-through element 210. The ends of the one or more conductors 217 at the first interface region 211 are exposed to be electrically contacted or coupled. Similarly, the ends of the one or more conductors 217 at the second interface region 212 are likewise exposed to be electrically contacted or coupled. A first electrical connector 220 (or similar device) may be assembled or affixed to the first interface region 211 and the conductors there. A second electrical connector 221 (or similar device) may be assembled or affixed to the second interface region 212 and the conductors there.

[0058] In some embodiments, the feed-through element 210 may be at least partially flexible. For example, in some embodiments the feed-through element 210 may comprise a flexible member that is similar to a ribbon cable.

[0059] The feed-through element 210 may also provide an electrical interface that provides a predetermined impedance characteristic for the one or more conductors 217. It should be understood that the impedance characteristics of individual conductors 217 may be the same or may be different. The one or more conductors 217 may be formed of predetermined thicknesses and predetermined widths. The one or more conductors 217 may be formed in predetermined geometric shapes or patterns and may include a ground plane or ground planes. The one or more conductors 217 may be formed of predetermined conductor compositions. Further, the one or more conductors 217 may be formed to have a predetermined DC resistance and/or a predetermined AC impedance. This may comprise including any manner of passive and/or active electrical components as part of either the feed-through element 210 or as part of subsequent electrical circuits. Further, in some embodiments the explosion proof electronics enclosure 200 may include interchangeable feed-through elements 210 of various impedances/resistances for use during the manufacturing process. As a result, the explosion proof electronics enclosure 200 can be assembled to comprise a desired impedance/resistance from among a plurality of possible impedances/resistances.

[0060] A cavity 225 is disposed proximate the first aperture 209. When the feed-through element 210 is installed in the explosion proof electronics enclosure 200, the feed-through element 210 passes through the first aperture 209 and the cavity 225. The cavity 225 thus opens to the first aperture 209 and to the second compartment 207.

[0061] The cavity 225 is sealed by injecting a potting material 230 therein, also surrounding and embedding the feed-through element 210 therein. The potting material 230 prevents a spark, flame, or explosion from passing between the first and second compartments 206, 207.

[0062] In some embodiments, compliance with a flame proof standard may require maintaining a small gap, a long flame path length, or both. The flame path length may be selected so that a flame may not propagate from one side of the explosion proof electronics enclosure 200 to the other side with sufficient heat or energy content to cause ignition, given a gap between the feed-through element 210 and the body 205.

[0063] In some embodiments, it is desired that gaps do not exist, as gaps may allow gasses to leak therethrough, and may allow possible gas ignition. Since gaps may allow ignition products to propagate through the joint, both the feed-through element 210 and first aperture 209 may be smooth and regular, i.e., to within a predetermined surface finish.

[0064] Potting material 230 is an epoxy, plastic, or other filling material which seals the cavity 225, thus preventing a flame or explosion from escaping through the cavity 225 or first aperture 209.

[0065] To ensure the potting material 230 is not dislodged due to the pressure related to an explosion, the cavity 225 comprises an undercut taper 226.

[0066] As part of the assembly process, the feed-through element 210 is disposed in the first aperture 209, such that the feed-through element 210 is inserted through the first aperture 209 and the cavity 225, wherein the one or more conductors 217 extend between the first interface region 211 and the second interface region 212, and wherein the first interface region 211 resides in the first compartment 206, and the second interface region 212 resides in the second compartment 207. The potting material 230 is then placed in the cavity 225, and takes the shape of the cavity 225, and is allowed to cure or harden. The feed-through element 210 is thus retained in the cavity 225 and the first aperture 209 with the potting 230.

[0067] In an embodiment, the feed-through element 210 is inserted through the first aperture 209 and the cavity 225 via the first compartment 206. In an embodiment, the feed-through element 210 is inserted through the first aperture 209 and the cavity 225 via the second compartment 207.

[0068] In an embodiment, the feed-through element 210 may be machined to a predetermined profile tolerance, wherein the junction between the feed-through element 210 and the first aperture 209 mates with sufficient precision to create a substantially explosion proof interface. For example, the feed-through element 210 may be manufactured to be thicker than desired and then the feed-through element 210 may be planed, milled, etched, ground, or otherwise processed until the explosion proof electronics enclosure 200 comprises a junction between the feed-through element 210 and the first aperture 209 having a desired size and shape and desired uniformity. The feed-through element 210 and/or the first aperture 209 may be manufactured to achieve one or more of a predetermined perimeter size, a predetermined perimeter shape, and/or a predetermined perimeter surface smoothness and/or uniformity. In an embodiment, the feed-through element 210 overlaps the first aperture 209 completely on one of the sides of the first aperture 209, with no portions of the aperture remaining uncovered, such that the feed-through element 210 acts as a stop to achieve a predetermined position in the first aperture 209.

[0069] The undercut taper 226 is provided such that when the potting material 230 cures or hardens, the potting material 230 is permanently placed. The undercut taper 226 results in a potting material 230 plug with a lower region 231 having a larger area than the opening 232 of the cavity 225. Therefore, upon explosive forces, the potting material 230 is trapped in the cavity 225, which results in an explosion proof junction between the first compartment 206 and second compartment 207.

[0070] The undercut taper 226 may be provided having a dovetailed shape with a flat region 227 proximate the opening 232 of the cavity 225, as is shown in FIG. 4. In another embodiment, the undercut taper 226 may be provided having a frustoconical shape with no flat region 227 proximate the opening 232 of the cavity 225. The angle of the undercut may be between about 10° and 50°. Preferably, the angle of the undercut is between about 15° and 25°. In FIG. 4, the angle of the undercut is illustrated as being approximately 20°, though this is merely an example of an embodiment.

[0071] In an embodiment, a support plate 240 is provided having a second aperture 241 therein. The support plate 240 is ultimately disposed proximate the first aperture 209, at the bottom of the cavity 225. In an embodiment, the potting material 230 is then introduced to the cavity 225, and the support plate 240 is lowered into the cavity 225. The support plate 240 acts as a dam to contain the potting material 230 as it cures or hardens. The support plate 240 also aids to keep the feed-through element 210 properly located during the curing or hardening process. The support plate 240 may simply fit into the bottom of the cavity 225, or may be disposed in a recess 242 proximate the bottom of the cavity 225, wherein the recess is a size and dimension to receive the support plate 240.

[0072] In an embodiment, the support plate 240 is placed in the cavity 225, and then the feed-through element 210 is passed through the cavity 225, second aperture 241, and the first aperture 209. In an embodiment, the feed-through element 210 is first passed through the second aperture 241, and then the support plate 240 and feed-through element 210 are subsequently placed into the cavity 225.

[0073] In some embodiments, the explosion proof electronics enclosure 200 may additionally include a seal or seals (not shown) between any portion of the body and the feed-through element 210. The seal or seals may comprise a solid seal or seals, such as O-rings, gaskets, or other components that may be disposed between other components. Alternatively, the seal or seals may comprise a liquid, paste, grease, or other material that does not have a predetermined shape and that can be applied to one or more of the components of the explosion proof electronics enclosure 200. The seal or seals may comprise a material that does not substantially change. Alternatively, the seal or seals may comprise a material that hardens, cures, or otherwise transforms or is transformed during or after the assembly process.

[0074] In an embodiment, the feed-through element 210 may receive one or more fasteners 235 that fasten the feed-through element 210 to the body 205 or other portion of the explosion proof electronics enclosure 200. In a related embodiment, the feed-through element 210 may include one or more fastener apertures 213. The one or more fastener apertures 213 may receive electrical conductors of any manner or may receive a connector or other component. The one or more fastener apertures 213 may include any manner of pads, through-plating, or other conductor coupling feature.

[0075] The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention. Accordingly, the scope of the invention should be determined from the following claims.