Pressure sensors with increased fatigue resistance

Abstract

An improved pressure sensor includes one or more features for reducing stress at a weld joint fixing a header assembly to a pressure port. The feature(s) can include an undercut formed in a bore of the pressure port and / or a backplate that at least partially covers the weld joint.

Description

Pressure Sensors with Increased Fatigue ResistanceCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit or priority of United States Provisional Patent Application No. 63 / 666,975, filed July 2, 2024, and titled “Pressure Sensors with Increased Fatigue Resistance,” the entirety of which is hereby incorporated by reference.FIELD OF THE TECHNOLOGY

[0002] The subject disclosure relates to sensing devices, such as pressure sensors. More specifically, this disclosure relates to improved pressure sensors that may have increased fatigue resistance.BACKGROUND OF TECHNOLOGY

[0003] Conventional pressure sensors are used in many applications. However, these conventional devices and their associated components may not be rated for use in certain operating environments. For example, some conventional pressure sensors include a header welded to a pressure port. However, this weld has proven to be prone to failure when the pressure sensor is used in relatively high pressure applications.

[0004] Accordingly, there is a need in the art for improved sensing devices, such as pressure sensors, capable of use in a greater operating conditions.SUMMARY OF THE TECHNOLOGY

[0005] The subject technology relates to improved pressure sensors. In examples, aspects of this disclosure relate to pressure sensors for use in high pressure applications. For example, aspects of this disclosure relate to improved micro-electro-mechanical system (MEMS) type pressure sensors that may have features for reduced stress and / or longer life spans. Sensors according to this disclosure may be configured for use in higher pressure applications in which conventional sensors are prone to failure. More specifically, aspects of this disclosure incorporate one or more features for reducing stress at a weld joint that fixes a header assembly to a pressure port.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] So that those having ordinary skill in the art to which the disclosed systems and techniques pertain will more readily understand how to make and use the same, reference may be had to the following drawings.

[0007] FIG. 1 is a cross-sectional view of a conventional MEMS pressure sensor, in accordance with aspects of this disclosure.

[0008] FIG. 2 is a partial cross-sectional view of a conventional pressure sensor and a graph illustrating stresses associated with a weld joint of the pressure sensor, in accordance with aspects of this disclosure.

[0009] FIG. 3 is a perspective view of a conventional pressure sensor demonstrating weld joint failure, in accordance with aspects of this disclosure.

[0010] FIG. 4 is a cross-sectional view of an improved MEMS pressure sensor, in accordance with aspects of this disclosure.

[0011] FIG. 5 is a cross-sectional view of the pressure sensor of FIG. 4, in accordance with aspects of this disclosure.

[0012] FIG. 6 shows impulse testing profiles associated with testing pressure sensors, in accordance with additional aspects of this disclosure.

[0013] FIGS. 7 includes a cross-sectional view of a portion of a conventional sensor and finite element analysis resulting from impulse testing of the sensor, in accordance with additional aspects of this disclosure.

[0014] FIG. 8 includes a cross-sectional view of a portion of an improved sensor and finite element analysis resulting from impulse testing of the sensor, in accordance with additional aspects of this disclosure.

[0015] FIG. 9 includes a cross-sectional view of a portion of an improved sensor and finite element analysis resulting from impulse testing of the sensor, in accordance with additional aspects of this disclosure.

[0016] FIG. 10 is a chart showing stresses associated with different sensor configurations, in accordance with aspects of this disclosure.

[0017] FIG. 11 includes a cross-sectional view of a portion of an improved sensor and finite element analysis resulting from impulse testing of the sensor, in accordance with additional aspects of this disclosure.

[0018] FIGS. 12A-12D include views of another improved pressure sensor in accordance with aspects of this disclosure.DETAILED DESCRIPTION

[0019] The subject technology overcomes many of the prior art problems associated with pressure sensors. In brief summan', the subject technology provides improved pressure sensors with increased robustness, which may be useful in higher pressure applications.

[0020] A conventional pressure sensor 100 is illustrated in FIG. 1. As shown there, the pressure sensor 100 generally includes a pressure port 102 defining a channel 104. The pressure port 102 has threads 106, which are an example of an attachment feature for securing the pressure sensor 100 to a pressurized volume (not shown). Once attached, pressurized fluid in the volume passes through the channel 104 to interface with a header assembly 108. The header assembly 108 may include a MEMS die assembly, which is configured to generate electrical signals in response to pressure applied at a MEMS die 110.

[0021] As also shown in FIG. 1. the pressure sensor 100 can include header pins 112 (electrically) connecting aspects of the header assembly 108 to external components (not shown). In some examples, the header pins 112 may be fixed to the header assembly via glass seals 114, e.g., via a glass-to-metal sealing operation. The pressure sensor 100 can also include a printed circuit board (PCB) 116 and / or other features, as is / are conventionally known. For example, the PCB 116 may facilitate signal conditioning, power management, and / or other functionality associated with the MEMS Die 110 and / or other aspects of the pressure sensor 100.

[0022] In the conventional pressure sensor 100. the pressure port 102 includes a bore 118 disposed generally opposite the threaded end and the 106 and the channel 104. The bore 118 is configured to receive the header assembly 108. FIG. 1 shows the header assembly 108 disposed in the bore 118. As also illustrated, the header assembly 108 can include a flanged periphery or flanged portion 120 that rests on a stepped surface 122 of the bore 118. In the conventional pressure sensor 100, the header assembly 108 is fixed to the pressure port 102 bywelding, e.g., at a weld joint 124 at an interface of the flanged periphery 120 and the pressure port 102.

[0023] In some applications, e g., higher pressure applications, the weld joint 124 may be prone to failure. One of the main requirements for pressure sensors is the number of pressure impulse cycles the sensor should complete without any failure or leakage. Although the conventional design of FIG. 1 can satisfy low-pressure applications, due to higher generated mechanical stress for high-pressure applications, cracks can propagate through the weld joint 124. Such cracks may cause an external leak or other failure. For instance, the w eld joint 124 is subject to stress as pressure increases and decreases. In some applications, it may be desirable for a pressure sensor to withstand up to about 1.7 million or more cycles with 6350 PSI or more applied pressure. Instead, the illustrated conventional design of FIG. 1 has demonstrated w eld failure at about 0.5 million cycles at these relatively high pressures.

[0024] FIG. 2 includes a partial, perspective, cross-sectional view of the pressure sensor 100 and a graph 200 showing generated stresses along the weld joint 124. More specifically, the graph 200 shows stresses (von Mises stresses) betw een a bottom extent of the weld joint 124. represented as point A, and a top extent of the weld joint 124, represented as point B. As shown, the highest stresses are located at the edges (e.g., top and bottom) of the weld joint 124.

[0025] FIG. 3 shows failure of the pressure sensor 100. More specifically, FIG. 3 demonstrates fonnation of a crack 302 at the weld joint 124. The crack 302 results in failure of the pressure sensor 100. For example, the pressurized gas intended to be sensed can leak through the pressure sensor 100 via the crack 302, resulting in leakage. In the example, the crack 302 formed prematurely during pressure impulse testing. In other examples, however, the crack 302 may form during use, resulting in inefficiencies associated with lost time,expense, and / or the like. As will be appreciated, the crack 302 is for example only. Other failures may also result at the weld joint 124.

[0026] Some conventional design features have been implemented in an attempt to reduce the stress at the weld joint 124, e.g., in an attempt to prevent the illustrated crack 302. For example, one conventional approach has been to create a threaded interface of the header assembly 108 and the pressure port 102. For example, first threads (not shown) may be formed on an outside surface area of the header assembly 108 and second, mating threads (also not shown) may be formed on an inside surface area of the bore 118 (shown in FIG. 1 , for example). In this conventional example, the threads engage with each other to mount the header inside the pressure port, e.g., by coupling the header to the pressure port. These threads may remove partial loading from the weld joint 124. In this approach, the header assembly 108 should be fully tightened to the pressure port 102 to take advantage of the threads. However, when tightening the header assembly 108 into position, there is no control on the orientation of the header assembly 108 (e.g., no rotational alignment). This is problematic for downstream assembly steps, including in instances in which the PCB 116 must be aligned with the header pins 112 for mounting. Designs with multi -headers (multi-channel pressure sensors) suffer even more from this approach because all headers should be aligned correctly to be able to install the PCB 116 over the corresponding header pins 112 of the multiple headers.

[0027] Another approach has been to use a relatively thicker header and / or a header with a smaller diameter. This approach may help reduce the amount of header deformation under the same applied pressure, similar to deformation of a clamped-clamped beam that becomes shorter and thicker, so deformation reduces under loading. However, this approach has its own limitations too. For example, the thicker header puts at risk the continuity of the glass seal material around the pins 112 (e.g., air pockets and / or voids are introduced) whichresults in degraded electrical insulation and dielectric strength properties (arcing or current leakage takes place at lower applied voltages). In addition, cracks may be introduced into the glass during fabrication due to higher variation of stress along the header thickness. Moreover, the limits for reducing the size of the header are limited. For example, the header assembly 108 must be sufficiently sized to install the MEMS die 110. Moreover, the glass seals cannot be positioned too close to each other, otherwise the mechanical strength of the header assembly 108 is compromised. Moreover, testing has proven that when the diameter becomes too small, the weld joint AB becomes too close to the glass seals, and when the laser weld operation is completed, due to amount of injected heat (thermal shock) the glass seals are cracked and the header assembly 108 starts leaking when the pressure is applied. Essentially, the failure mode is moved from the weld joint to the glass seal in some of these designs.

[0028] Accordingly, there is a need for other design approaches. FIG. 4 shows an example pressure sensor 400 according to aspects of this disclosure. In FIG. 4, reference numerals used in FIG. 1 are used to show corresponding components, including the pressure port 102, the header assembly 108, and the bore 118.

[0029] Unlike in the conventional pressure sensor 100, the pressure sensor 400 includes an undercut 402 in the wall forming the bore 118. Specifically, in the illustrated example, the bore 118 includes a stepped profile, having a substantially cylindrical body portion 404, the stepped surface 122 (which is substantially horizontal in the orientation of FIG. 4), and a flanged opening portion 406. The flanged opening portion 406 has a larger diameter than the cylindrical body portion 404, and the stepped surface 122 extends between the flanged opening portion 406 and the cylindrical body portion 404. As will be appreciated, the flanged opening portion 406 and the stepped surface 122 may form a counterbore about the cylindrical body portion 404, e.g., sized to receive the flanged portion 120 of the headerassembly 108. The undercut 402 is formed proximate the junction of the flanged opening portion 406 and the stepped surface 122 of the bore 118.

[0030] The undercut 402 is illustrated as being substantially semi-circular in profile, effectively forming a groove or indent about the circumference of the bore 118. In examples, the undercut 402 may have a radius of from about .005” to about .05”. Although illustrated as semi-circular, the undercut 402 may alternatively have different profiles, including but not limited to arcuate, angular, and / or other profiles. Moreover, although FIG. 4 shows the undercut 402 as being fornied in the flanged opening portion 406 of the bore 118, in other examples at least a portion of the undercut 402 may be formed in the stepped surface 122 of the bore 118, e.g., proximate the junction between the flanged opening portion 406 and the stepped surface 122. In still further examples, the undercut 402 may be formed entirely in the stepped surface 122. As will be appreciated from this disclosure, the undercut 402, regardless of where positioned, provides a recess or relief proximate a portion of the header assembly 108, when the header assembly 108 is coupled (e.g., by welding) to the pressure port 102.

[0031] According to aspects of this disclosure, the undercut 402 is close to or proximate the weld joint 124 formed to secure the header assembly 108 to the pressure port 102. More specifically, assembly of the pressure sensor 400 can include positioning the header assembly 108 into the bore 118 such that the flanged portion 120 of the header assembly 108 contacts the stepped surface 122 of the bore 118. In this position, an outer surface 408 of the flanged portion 120 of the header assembly 108 is disposed proximate the flanged opening portion 406 of the bore 118. The weld joint 124 is then formed, e.g., by laser welding, to join the header assembly 108 to the pressure port 102 at the outer surface 408 of the flanged portion 120 and the flanged opening portion 406 of the bore 118. For example, the header assembly 108 and the pressure port 102 may be formed such that a gap is formed between the outer surface 408of the flanged portion 120 and the flanged opening portion 406 of the bore 118, with the weld joint 124 being formed in the gap. In at least some examples, metal used to fonn the weld joint 124 may be at least partially disposed in the undercut 402. For instance, during the welding process some molten metal may flow between the header assembly 108 and the pressure port 102 and into the void or recess created by the undercut.

[0032] When the header assembly 108 is welded to the pressure port 102, e.g., at the weld joint 124. the undercut 402 effectively reduces the generated stress at the weld joint 124 during use of the pressure sensor 400. By reducing the stress in this manner, crack propagation through the weld joint 124, which is a common failure mode in conventional sensors (e.g., as shown in FIG. 3 and discussed above), can be significantly reduced.

[0033] As also shown in FIG. 4, the sensor 400 can also optionally include a backplate 410. The backplate 410 is disposed on top of and extends across at least a portion of each of the pressure port 102 and the header assembly 108. Accordingly, the backplate 410 is disposed over the weld joint 124. In the illustrated example, the backplate 410 may be formed as aring- shaped plate defining a central opening through which the header pins 112 can extend. In other examples, the backplate 410 may have any opening or openings that do not impede the header pins 112 and / or other components that extend at least partially above the header assembly 108. The backplate 410 may be secured in the illustrated position using mechanical fasteners, e.g., screws, bolts, or the like, and / or any other means that secures the backplate 410. In some examples, a weld, such as a peripheral weld, can be added to fix the backplate 410 to the pressure port 102. In still further examples, a weld may be added at a junction of the backplate 410 and the header assembly 108, e.g., at an inner diameter of the ring-shaped backplate 410. As will be appreciated, once formed, the weld joint 124 may be machined or otherwise formed to facilitate flush contact of the backplate 410 with the tops of the pressure port 102 and theheader assembly 108. In still further examples, the backplate 410 may have a cutout or void that accommodates a clearance fit with the weld joint 124.

[0034] In operation, the backplate 410 may prevent the header from undergoing large defonnations when pressure is applied to the pressure sensor 400, e.g., during use. For instance, the rigidity provided by the backplate 410 can reduce deformations. As will be appreciated, smaller deformations cause less mechanical stress, which consequently increases the life span of the sensor.

[0035] The pressure sensor 400 is illustrated as including both the undercut 402 and the backplate 410. Each of these features may reduce the stress at the eld joint 124. In other examples, only the undercut 402 or only the backplate 410 may be provided. For example, FIG. 5 is another cross-sectional view of the sensor 400, in which the backplate 410 is not included. FIG. 5 also shows a possible profile of the weld joint 124, which may be formed via laser welding. In the illustrated example of FIG. 5, the weld joint 124 is substantially tapered, e.g., being wider proximate a top surface 502 of the pressure sensor 400 and relatively narrower at distances spaced from the surface 502. In examples, the header assembly 108 and / or the pressure port 102 may be configured to accommodate the tapered weld. For instance, and without limitation, the surfaces of the header assembly 108, e.g., the outer surface 408 of the flanged portion 120 of the header assembly 108, and / or of the pressure port 102, e.g., the flanged opening portion 406 of the bore 118 may be angled relative to each other to create a "V" or other similar shape. In these examples, one or both of the outer surface 408 and the flanged opening portion 406 may be other than cylindrical. As also illustrated in FIG. 5, some weld material 504 may flow7into the undercut 402 during assembly.

[0036] As just described, the undercut 402 and / or the backplate 410 have been measured to improve the impulse lifetime of pressure sensors at least in part by removing thestress concentration zone away from the weld joint 124 and / or reducing the header deformation in the presence of pressure. In examples, the undercut 402 adds a groove to the pressure port 102, proximate the bottom of the weldjoint 124. When used, the backplate 410 is disposed on top of header 108 / pressure port 102 assembly.

[0037] FIGS. 6-9 show details and results of stress testing performed using examples of this disclosure. Specifically, FIG. 6 shows a first pressure profile 602 and a second pressure profile 604 used to perform impulse testing on various pressure sensors. As illustrated, the first pressure profile 602 is a sinewave. The second pressure profile 604 is a damped waveform. These profiles are for example only; other profiles and / or pressure tests may be used.

[0038] FIG. 7 shows results of the impulse testing performed on a conventional pressure sensor 700, which may be the pressure sensor 100. FIG. 7 includes a schematic cross- sectional view of the pressure sensor 700. FIG. 7 also includes finite element analysis 702 showing the high stresses at the weld joint 124. In the example, and similar to FIG. 2, the von Mises stresses are particularly high at the lower edge of the outer surface (e g., the surface corresponding to the outer surface 408) of the header assembly 108.

[0039] FIG. 8 shows results of the impulse testing performed on another pressure sensor according to aspects of this disclosure. Specifically, FIG. 8 includes a schematic cross- sectional view of a pressure sensor 800 that includes an undercut 802, which may be the undercut 402. In more detail, the pressure sensor 800 has a pressure port 804 defining a bore 806 and a header assembly 808 disposed in the bore 806. A weld joint 810, generally corresponding to the weld joint 124 described herein, is formed at an interface of the header assembly 808 and the bore 806 to fix the header assembly 808 to the pressure port 804. In the example of FIG. 8, unlike in previous examples, the bore 806 in the pressure port 804 is not stepped, e.g., omitting the stepped surface 122 of FIGS. 4 and 5. Save for the undercut 802,the pressure sensor 800 may be substantially identical to the pressure sensor 700 illustrated in FIG. 7.

[0040] FIG. 8 also includes finite element analysis 814 showing that the inclusion of the undercut 802 greatly reduces stresses at the weld joint 810. especially at the bottom edge of the weld joint 810. As also shown, the stresses are moved away from the weld joint 810, into the undercut 802. In the example of FIG. 8, the undercut 802 has a diameter of .060 inches and is formed in the sidewall of the bore in the pressure port. As noted above, the pressure sensor 800 does not include a backplate. As evident from FIG. 8, the inclusion of the undercut 402 significantly reduces stresses.

[0041] FIG. 9 shows results of the impulse testing performed on a pressure sensor according to aspects of this disclosure. Specifically. FIG. 9 includes a schematic cross- sectional view of a pressure sensor 900 that includes both an undercut 902, which may the undercut 402, and the backplate 904, which may be the backplate 410. In more detail, the pressure sensor 900 includes a pressure port 906 defining a bore 908 and a header assembly 910 disposed in the bore 908. A weld joint 912, generally corresponding to the weld joint 124 described herein, is formed at an interface of the header assembly 910 and the bore 908 to fix the header assembly 910 to the pressure port 906. As with the example of FIG. 8, the bore 908 in the pressure port 906 is not stepped, e g., omitting the stepped surface 122 of FIGS. 4 and 5. The pressure sensor 900 may be substantially identical to the pressure sensor 800 illustrated in FIG. 8, but also include the backplate

[0042] FIG. 9 also includes finite element analysis 914 illustrating the relatively lower stresses at the weld joint 912. As shown, the stresses are moved away from the weld joint 912, into the undercut 902. Moreover, because of the backplate 904, the magnitude of the stresses are further reduced relative to the sensor 800.

[0043] FIG. 10 includes a summary' chart 1000 demonstrating improvements associated with aspects of this disclosure. In FIG. 10, the first row corresponds to the impulse testing having the results shown in FIG. 7, e.g., testing done on the conventional sensor 100. The second row shows results associated with FIG. 8, e.g., in which the undercut 802 is provided (but not the backplate). The third row shows results associated with impulse testing on another pressure sensor (not illustrated in the FIGS.) that includes a backplate, but not the undercut. And the fourth row shows results associated with FIG. 9, e.g., in which both the undercut 902 and the backplate 904 are provided. As illustrated, in these examples the undercut 802, 902 has a diameter of 0.060” and the backplate has a thickness of 0.1”. As also shown in the summary chart 1000, the use of only the backplate provided a 38% decrease in von-Mises stresses at the tip of the weld joint, while the use of only the undercut 402 provided a 93% decrease in those von-Mises stresses. Moreover, the use of both the undercut 402 and the backplate 410 resulted in a 95% decrease in the von Mises stresses.

[0044] As will be appreciated, the improvements over conventional sensors may be beneficial in a number of applications. For example, for applications that can use the conventional sensor 100, the improved sensors according to this disclosure can be used to increase the margin of the product safety, which may allow for improved results and / or use of the sensor in different areas, including in the aerospace industry. Moreover, the robust sensors according to this disclosure can meet higher pressure impulse requirements, thereby providing a reliable solution in additional applications.

[0045] FIG. 11 shows results of additional testing on sensors according to aspects of this disclosure. Specifically, FIG. 11 includes a schematic cross-sectional view7of a pressure sensor 1100 that includes an undercut 1102 and a backplate 1104. As with other embodiments, a weld joint 1106 is formed at a junction of a pressure port 1108 and a header assembly 1110.The pressure sensor 1100 may be substantially the same as the pressure sensor 900 discussed herein.

[0046] FIG. 11 also includes a graph 1112 that shows stresses (von Mises stresses) between a bottom extent of the weld joint 1106, represented as point A. and a top extent of the weld joint 1106, represented as point B, for different thicknesses of the backplate 1104. As illustrated, for any thickness equal to or greater than about . 1 inch, the stresses are about the same at each of Point A and Point B, whereas for smaller thicknesses stresses increase. While FIG. 11 suggests that the thickness of the backplate 1104 may have some influence on stress reduction in the pressure sensor 1100, other characteristics can also have an impact. For instance, the type of material used for the backplate 1104 and / or properties of that material can have an effect.

[0047] FIGS. 12A-12D includes images of an additional pressure sensor according to aspects of this disclosure. More specifically. FIGS. 12A-12D show various views of a pressure sensor 1200 that includes a pressure port 1202 and multiple header assemblies 1204 (two of which are shown). For example, the pressure sensor 1200 may be a differential pressure sensor that includes tw o header assemblies 1204.

[0048] As shown in FIG. 12A, the pressure port 1202 defines two bores 1208. For instance, each of the bores 1208 may be substantially similar to the bore 118 discussed above. In other examples, one or more of the bores 1208 may be substantially similar to the bores 806, 908, discussed above. As also shown in FIG. 12A (and also in FIG. 12D), each of the bores 1208 includes an undercut 1210 or groove, like the undercuts 402. 802, 902, 1102 discussed above. Each of the undercuts 1210 is illustrated as being substantially continuous about the diameter of the respective bore 1208, although the undercuts 1210 need not be continuous in other examples. Without limitation, the undercuts 1210 may be discontinuous about thediameter. As also illustrated in FIG. 12A, two threaded openings 1212 also are formed in an upper surface of the pressure port 1202.

[0049] The pressure port 1202 illustrated in FIGS. 12A-12D also includes an upper rim 1214. generally circumscribing a cover-receiving bore 1216. as detailed further herein. In some examples, the upper rim 1214 may be omitted. As will be appreciated, the arrangement, size, shape, and / or locations of the features of the pressure port 1202 are for example only.

[0050] FIG. 12B shows the header assemblies 1204 disposed in the bores 1208. During assembly, the header assemblies may be placed into the bores 1208 and fixed in the bores, as detailed further herein. For example, the header assemblies 1204 may be welded, e.g.. laser welded, to the pressure port 1202. For instance. FIG. 12B shows a plurality of welds 1206 formed at an interface of the header assemblies 1204 and the bores 1208. The welds 1206 may be the weld joints 124, discussed above. Although the welds 1206 are illustrated as a plurality of spot welds fonned about a periphery of the header assemblies 1204, other welds may also be used, as will be appreciated by those having ordinary skill in the art with the benefit of this disclosure.

[0051] FIG. 12C shows a backplate 1218 disposed partially over the header assemblies 1204. Specifically, the backplate 1218 is configured to be disposed in the cover receiving bore 1216 defined by the upper rim 1214. The backplate 1218 has two openings 1220 through which header pins of the header assemblies 1204 extend. Otherwise, the backplate 1218 extends over the welds 1206 formed between the header assemblies 1204 and the pressure port 1202. As also shown in FIG. 12C, the backplate 1218 is secured to the pressure port 1202 via screws 1222, which are received in the threaded openings 1212. Of course, the screws 1222 are but one example of fasteners that can secure the backplate 1218. As also illustrated in FIG. 12C,an outer periphery of the backplate 1218 may also or alternatively be welded to the upper rim1214 of the pressure port 1202, e.g., at a weld 1224, to secure the backplate 1218 in position.

[0052] FIG. 12D includes a cross-sectional view of the sensor 1200 of FIG. 12C and a magnified portion of the cross-sectional view. As illustrated, aspects of the sensor 1200 are substantially the same as the sensors described herein previously. The pressure port 1202 includes the two bores 1208 formed therein for receiving the header assemblies 1204. The bores 1208 include a stepped profile, generally as described above with the example of FIGS. 4 and 5. Each of the bores 1208 is configured to be in fluid communication with a pressurized fluid via an associated fluid passageway 1226 extending through the pressure port 1202. In the example of FIG. 12D, the pressure port 1202 has external threads 1230 to facilitate connection of the pressure sensor 1200 to a pressurized vessel (not shown).

[0053] FIG. 12D, and in particular the magnified partial view, also shows that a bottom surface of the backplate 1218 has indentations 1220 or recesses. The indentations may provide clearance for the weld joints 1206, e.g., such that if the weld joints 1206 extend above the top surface of the pressure port 1202 and / or the top surface of the header assembly 1204, the backplate 1218 will still sit flush in the backplate receiving bore 1216. In the illustrated example, because of the indentations 1232, the backplate 1218 may only make contact with the header assemblies 1204. Of course, varying the size and position of the indentations 1232 can cause other points of contact for the backplate 1218, including at one or both of the header assemblies 1204 and / or the pressure port 1202.

[0054] As will be appreciated from the foregoing, aspects of this disclosure can be incorporated into many sensors, including high-pressure sensors, absolute pressure sensors, gauge pressure sensors, differential pressure sensors, and / or any other pressure sensors to meet increased pressure and / or impulse cycle demands.

[0055] While the subject technology has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and / or modifications can be made to the subject technology without departing from the spirit or scope of the subject technology7. For example, each claim may depend from any or all claims in a multiple dependent manner even though such has not been originally claimed.

Claims

WHAT IS CLAIMED IS:

1. A sensing device comprising: a pressure port defining a bore and having an undercut formed in an inner surface of the bore; a header assembly disposed in the bore of the pressure port; and a weld joint formed at an interface of the pressure port and the header assembly, proximate the undercut.

2. The sensing device of claim 1, wherein the undercut is a groove formed around a circumference of the bore.

3. The sensing device of any one of claim 1 or claim 2, wherein: the bore comprises a stepped profile comprising a body portion having a first diameter, a stepped surface extending radially outwardly from the body portion, and a flanged opening portion having a second diameter larger than the first diameter.

4. The sensing device of claim 3, wherein: the header assembly comprises a flanged portion; and the header assembly is disposed in the bore such that the flanged portion contacts the stepped surface of the bore.

5. The sensing device of claim 4, wherein the weld joint is formed between an outer surface of the flanged portion of the header assembly and the flanged opening portion.

6. The sensing device of claim 5, wherein the outer surface of the flange portion of the header assembly and the flanged opening portion of the bore are angled relative to each other.

7. The sensing device of claim 4 or claim 5, wherein the undercut is formed at least partially in at least one of the flanged opening portion or the stepped surface.

8. The sensing device of claim 1, further comprising a backplate extending over the weld joint, wherein the backplate is coupled to the pressure port or the header assembly.

9. The sensing device of claim 8, wherein the backplate comprises one or more recesses generally aligned w ith the weld joint.

10. The sensing device of claim 8 or claim 9, wherein: the backplate contacts at least a portion of the header assembly; and the backplate is at least one of welded or fastened to the pressure port.

11. The sensing device of claim 8, wherein the backplate has a thickness of at least about 0. 1 inches.

12. The sensing device of claim 1. wherein the bore comprises a first bore and the header assembly comprises a first header assembly, the sensing device further comprising: a second bore formed in the pressure port at a position spaced from the first bore, the second bore having a second undercut formed in an inner surface of the second bore;a second header assembly disposed in the second bore of the pressure port; and a second weld joint formed at an interface of the pressure port and the second header assembly, proximate the second undercut.

13. The sensing device of claim 12, further comprising a backplate coupled to the pressure port and disposed over the first weld joint and the second weld joint, wherein the backplate comprises a first opening aligning with the first header assembly and a second opening aligning with the second header assembly.

14. The sensing device of claim 13, wherein the backplate comprises one or more recesses formed in a surface facing the first header assembly and the second header assembly, the one or more recesses aligning with the first weld joint or the second weld joint.

15. The sensing device of claim 13 or claim 14, wherein: the pressure port further comprises an upper rim defining a backplate receiving bore; the backplate is disposed in the backplate receiving bore, and the backplate is welded to the upper rim.

Images