An embedded stress sensor

Abstract

The present application provides an embedded stress sensor for being embedded in a curing material to measure the stress of the curing material, which comprises: a main housing internally forming a sealed installation cavity; at least one strain beam fixedly connected to the main housing at one axial end and arranged in the sealed cavity isolated from the curing material; the sealed cavity is communicated to the installation cavity through a communication port on the main housing; a stress measurement circuit arranged on a first side surface of the strain beam in a thickness direction of the strain beam; an electronic module assembly at least partially arranged in the installation cavity, partially protruding into the sealed cavity from the communication port and electrically connected to the stress measurement circuit; and at least one anchoring element fixedly corresponding to the other axial end of the strain beam and anchored in the curing material. The stress sensor of the present application can be embedded in the curing material at a lower cost to measure the stress of the curing material.

Description

Technical Field

[0001] This application relates to the field of sensor technology, and more specifically to an embedded stress sensor. Background Technology

[0002] When conducting long-term monitoring of the structure of solidified building materials, sound waves, ultrasonic waves, frequency-modulated electromagnetic waves, or infrared radiation can be used to scan the material from the outside to locate internal volumetric defects such as cracks. However, these methods cannot monitor stress changes prior to crack formation. Other sensors, such as distributed fiber optic sensors and vibrating wire sensors, can be embedded in building materials for long-term stress monitoring. However, these methods are more expensive due to higher material and data acquisition / processing costs. For example, the vibration signals obtained by vibrating wire sensors require dedicated acquisition modules, and the optical signals obtained by fiber optic sensors require specialized demodulation.

[0003] The information disclosed in the background section of this invention is only intended to enhance the understanding of the general background of this invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides an embedded stress sensor that can monitor the stress within a cured material by pre-embedding it, while simultaneously reducing costs.

[0005] This invention provides an embedded stress sensor for measuring the stress of a cured material by embedding it within the material, comprising:

[0006] A main housing that forms a sealed mounting cavity inside;

[0007] At least one strain beam is fixedly connected to the main housing at one axial end and disposed in a sealed cavity isolated from the cured material; the sealed cavity is connected to the mounting cavity through a communication port on the main housing; a stress measurement circuit is disposed on a first side surface of the strain beam in the thickness direction;

[0008] An electronic module assembly, at least partially disposed in the mounting cavity, extends partially from the communication port into the sealed cavity and is electrically connected to the stress measurement circuit;

[0009] and at least one anchoring element that is fixed to the other axial end of the strain beam and anchored in the cured material.

[0010] Preferably, the main housing includes a seat having a recessed cavity with an upper opening and a cover that closes the upper opening.

[0011] Preferably, the strain beam is integrally connected to the base at one end of its axial direction.

[0012] Preferably, the stress measurement circuit includes at least one Wheatstone bridge, the strain beam includes a plate portion and a thickened portion formed by only a portion of the plate portion thickening towards a second side in the thickness direction, and the Wheatstone bridge includes two first thick-film resistors located on the back side of the thickened portion and two second thick-film resistors located outside the back side of the thickened portion.

[0013] Preferably, the thickened portion is located at one axial end of the strain beam and is integrally connected to the seat in the axial direction.

[0014] Preferably, it further includes at least one sleeve that is fitted onto the outside of the strain beam at one axial end, corresponding to the strain beam; one end of the sleeve is sealed to the base, and the other end is sealed to the connecting part integrally connected to the other axial end of the strain beam.

[0015] Preferably, the anchoring element extends axially and is fixed to the connection portion, and includes at least one protrusion that protrudes outward in the transverse plane to be anchored in the cured material.

[0016] Preferably, the strain measurement circuit, which is electrically connected to the electronic module assembly, is additionally provided on the side wall of the strain beam.

[0017] Preferably, the electronic module assembly includes a circuit board fixed to the bottom surface of the mounting cavity, and the first side surface of the strain beam having the stress measurement circuit is coplanar with the bottom surface of the mounting cavity.

[0018] Preferably, there are at least two strain beams, and their axes are arranged orthogonally to each other.

[0019] The stress sensor of the present invention can be embedded in a cured material at a low cost to measure the stress of the cured material. Attached Figure Description

[0020] Figure 1 This is a perspective view of an embedded stress sensor according to a preferred embodiment.

[0021] Figure 2 This is a perspective view of a portion of the structure of an embedded stress sensor according to a preferred embodiment.

[0022] Figure 3 This is a top view of a portion of the structure of an embedded stress sensor according to a preferred embodiment.

[0023] Figure 4 This is a perspective view of a portion of the structure of an embedded stress sensor according to a preferred embodiment.

[0024] Figure 5 This is a perspective cross-sectional view of an embedded stress sensor according to a preferred embodiment. Detailed Implementation

[0025] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings. The following embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. In the following description, the same reference numerals are used to denote the same or equivalent elements, and repeated descriptions are omitted.

[0026] In the description of this application, it should be understood that the terms "upper," "lower," "inner," "outer," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the prepositions "first," "second," etc., are only used for the purpose of distinguishing the modified objects, and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] It should also be further understood that the term "and / or" as used in this application specification and the corresponding claims refers to any combination of one or more of the listed items, as well as all possible combinations.

[0029] like Figures 1 to 5 As shown. In a preferred embodiment of the present invention, the stress sensor 100 includes a main housing (not labeled) and an electronic module assembly 4 disposed at least partially within a mounting cavity 20 formed within the main housing. The main housing may include a base 2 and a cover 8. The base 2 has a recess (not shown) with an upper opening. The cover 8 closes the upper opening of the recess. For example, the upper opening of the recess may form an upward-facing support step 20b. The cover 8 is supported and positioned on the support step 20b and may be welded to the edge of the upper opening of the recess to form a weld 2f, thereby forming a sealed mounting cavity 20 surrounded by the base 2 and the cover 8.

[0030] The stress sensor 100 also includes strain beams 1a and 1b, and stress measurement circuits 13 respectively disposed on the first side surface (i.e., the upper side surface in the figure) in the thickness direction of strain beams 1a and 1b. Both strain beams 1a and 1b are fixedly connected to the base 2 at one axial end. The stress sensor 100 also includes anchoring elements 6, which are correspondingly fixed to the other axial ends of strain beams 1a and 1b. The anchoring elements 6 are used for anchoring within the cured material. The strain beams 1a and 1b are each disposed in a sealed cavity 70 isolated from the curing material. For example, the strain beams 1a and 1b can each be disposed inside a sleeve 7. One end of the sleeve 7 is sealed to the seat 2, and the other end is sealed to a connecting part 14 integrally connected to the other end of the strain beam 1a. In particular, the sleeve 7, the connecting part 14 and the seat 2 are all made of metal. Thus, one end of the two sleeves 7 is respectively welded to the surface 2a and the surface 2b of the seat 2 to form a weld 7a, and the other end is respectively welded to an annular support step 141a formed on the connecting part 14 to form a weld 7b.

[0031] Stress measurement circuits 13 are provided on the upper surfaces of strain beams 1a and 1b to measure the stress on strain beams 1a and 1b respectively. Surfaces 2a and 2b are each connected inward to the mounting cavity 20 via a connecting port 21, thereby connecting the mounting cavity 20 to the sealed cavity 70 containing the stress measurement circuits 13. This provides an electrical connection channel between the stress measurement circuits 13 and the electronic module assembly 4. For example, at least a portion of the electronic module assembly 4 extends into the two mounting cavities 20 from the connecting ports 21, and multiple pads 401a on this portion are electrically connected to the pads 132 of the stress measurement circuits 13 via several leads 133. The stress measurement circuits 13 are housed within the sealed cavity 70, thus isolating them from curing materials such as concrete to prevent chemical corrosion and contact with strain beams 1a and 1b that could affect the measurement accuracy.

[0032] During the gradual curing process of the curing material, the anchoring element 6 can anchor the ends of strain beams 1a and 1b away from the main housing into the curing material, while at the ends of strain beams 1a and 1b closer to the main housing, another strain beam 1b and 1a, along with the main housing, can provide anchoring in the curing material. This ensures that both ends of strain beams 1a and 1b are anchored in the curing material. Specifically, the cross-sectional area of ​​the anchoring element 6 is larger than the outer circumferential cross-sectional area of ​​the sleeve 7. For example, the anchoring element 6 extends axially and is fixed to the connecting portion 14. It may include protrusions 61 that project outwards in the transverse plane to be anchored into the curing material. These protrusions 61 can be disc-shaped, or two or more can be provided. These protrusions 61 can be spaced apart axially along the corresponding strain beams, allowing the curing material and the anchoring element 6 to interpenetrate and reinforce the anchoring effect. In other schemes, the cross-sectional area of ​​the anchoring element 6 does not necessarily need to be greater than the outer circumferential cross-sectional area of ​​the sleeve 7. For example, the anchoring element 6 can be a divergent claw shape, thus anchoring itself into the solidified material. The cross-section of the seat 2 in both directions perpendicular to the strain beams 1a and 1b can also be greater than the corresponding outer circumferential cross-sectional area of ​​the sleeve 7.

[0033] The stress measurement circuit 13 may include four thick-film resistors printed on the upper surfaces of strain beams 1a and 1b, and printed wires 131 connecting them to form a Wheatstone bridge. The thick-film resistors also need to be sintered to reliably adhere to the surface of the strain beams. When strain beams 1a and 1b are conductors such as metals, the thick-film resistors and printed wires 131 are disposed on an additional insulating layer disposed on the upper surfaces of strain beams 1a and 1b. In particular, the strain beam may include a plate portion 11 disposed in the vertical direction of thickness and a thickened portion 12 formed by only a portion of the plate portion 11 thickening towards a second side in the thickness direction (i.e., the downward direction opposite to the first side direction). The Wheatstone bridge accordingly includes two thick-film resistors 13a located on the back side of the thickened portion 12 and two thick-film resistors 13b located outside the back side of the thickened portion 12. In this way, the strain beam can output a corresponding electrical signal not only when subjected to bending stress, but also when subjected to tensile stress only. The side portion of the plate portion 11 and / or the outer edge of the thickened portion 12 can form a clearance fit with the inner wall of the sleeve 7.

[0034] Preferably, strain beams 1a and 1b are integrally connected to the base 2 and / or the connecting portion 14 at one end of their axial direction. This ensures that strain beams 1a and 1b are subjected to less installation stress. The electronic module assembly 4 may include a circuit board 40 fixed to the bottom surface 20a of the mounting cavity 20. The upper surface of the strain beam 1a, which may be provided with stress measurement circuit 13, is coplanar with or has a slight height difference from the bottom surface of the mounting cavity 20. For example, the electronic module assembly 4 may include a main body portion 400 completely located inside the mounting cavity 20, and an extension portion 401 formed by extending from the corresponding end of the main body portion 400 along the corresponding strain beams 1a and 1b toward the connecting portion 14. The outer end of the extension portion 401 extends outward from the corresponding communication port 21 to mount the solder pad 401a.

[0035] The connecting portion 14 may include a flange portion 141 perpendicularly connected to the end of the strain beam away from the seat 2, and a connecting post 142 integrally and coaxially connected to the outer end of the flange portion 141. A blind hole 6a may be formed at the corresponding end of the anchoring element 6, which can be threadedly connected to the connecting post 142. The sleeve 7 may include a sleeve body 71 and a support ring 72 extending inward from the end of the sleeve body 71 away from the seat 2. After the sleeve 7 is fitted onto the corresponding strain beam on the side facing the seat 2, the support ring 72 can be supported and positioned on the flange portion 141, and can be welded to the annular support step 141a formed on the flange portion 141 to form a weld 7b. In some other embodiments, alternatively or additionally, the end of the anchoring element 6 facing the seat 2 may also be directly welded to the outer wall of the corresponding end of the sleeve 7.

[0036] The stress sensor 100 may also include a cable assembly 5 that is electrically and hermetically connected from the outside of the mounting cavity 20 to the electronic module assembly 4. For example, a through hole (not marked) may be provided on the side wall of the mounting cavity 20, through which the cable 51 of the cable assembly 5 extends into the mounting cavity 20 and is electrically connected to the electronic module assembly 4. The outside of the cable 51 is sealed by a sealing plug 52, which is sealed and fixed in the through hole.

[0037] In the above embodiments, the cover 8 is preferably circular to facilitate welding.

[0038] In some other simplified embodiments, the stress sensor 100 may consist of only a strain beam 1a or strain beam 1b, and be disposed in a suitable manner in a cured material, such as a specific portion within a beam, where the tensile stress is primarily generated by the bending moment.

[0039] In the above embodiments, the sidewall of at least one of the strain beams 1a and 1b (see reference) Figure 5 The cross-sections of strain beams 1a and 1b in the circuit may be additionally provided with strain measurement circuits, which are electrically connected to circuit board 40.

[0040] In some other embodiments, the stress sensor 100 may be further equipped with a strain beam orthogonal to both strain beams 1a and 1b to measure stress in three different directions. The end of the additional strain beam near the base 2 may be connected to the upper surface of the base 2 by welding or integral connection. In this case, the cover 8 and the circuit board 40 need to shrink accordingly or the base 2 needs to expand accordingly to avoid interference with the additional strain beam. The first side of the additional strain beam faces the circuit board 40.

[0041] The scope of this disclosure is not limited by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be included in this disclosure.

Claims

1. An embedded stress sensor (100), characterized in that, For measuring the stress of a cured material by embedding it in the cured material, it includes: A main housing that forms a sealed mounting cavity (20) inside; At least one strain beam (1a) is fixedly connected to the main housing at one end in the axial direction and disposed in a sealed cavity (70) isolated from the cured material; the sealed cavity (70) is connected to the mounting cavity (20) through a communication port (21) on the main housing; a stress measuring circuit (13) is disposed on a first side surface in the thickness direction of the strain beam (1a); An electronic module assembly (4) is at least partially disposed in the mounting cavity (20), which extends partially from the communication port (21) into the sealed cavity (70) and is electrically connected to the stress measurement circuit (13); and at least one anchoring element (6) that is fixed to the other axial end of the strain beam (1a) and anchored to the cured material.

2. The embedded stress sensor (100) according to claim 1, characterized in that, The main housing includes a seat (2) with a recessed cavity having an upper opening and a cover (8) that closes the upper opening.

3. The embedded stress sensor (100) according to claim 2, characterized in that, The strain beam (1a) is integrally connected to the seat (2) at one end of its axial direction.

4. The embedded stress sensor (100) according to claim 2, characterized in that, The stress measurement circuit (13) includes at least one Wheatstone bridge. The strain beam (1a) includes a plate portion (11) and a thickened portion (12) formed by only a portion of the plate portion (11) thickening toward a second side in the thickness direction. The Wheatstone bridge includes two first thick-film resistors (13a) located on the back side of the thickened portion (12) and two second thick-film resistors (13b) located outside the back side of the thickened portion (12).

5. The embedded stress sensor (100) according to claim 4, characterized in that, The thickened portion (12) is located at one axial end of the strain beam (1a) and is integrally connected to the seat (2) in the axial direction.

6. The embedded stress sensor (100) according to claim 2, characterized in that, It also includes at least one sleeve (7) that is fitted onto the outside of the strain beam (1a) at one axial end, corresponding to the strain beam (1a); one end of the sleeve (7) is sealed to the seat (2), and the other end is sealed to the connecting part (14) integrally connected to the other axial end of the strain beam (1a).

7. The embedded stress sensor (100) according to claim 6, characterized in that, The anchoring element (6) extends axially and is fixed to the connection portion (14), and includes at least one protrusion (61) that protrudes outward in the transverse plane to be anchored in the cured material.

8. The embedded stress sensor (100) according to claim 7, characterized in that, The strain measurement circuit, which is electrically connected to the electronic module assembly (4), is additionally provided on the side wall of the strain beam (1a).

9. The embedded stress sensor (100) according to claim 1, characterized in that, The electronic module assembly (4) includes a circuit board (40) fixed to the bottom surface (20a) of the mounting cavity (20), and the first side surface of the strain beam (1a) on which the stress measurement circuit (13) is located is coplanar with the bottom surface of the mounting cavity (20).

10. The embedded stress sensor (100) according to any one of claims 1 to 9, characterized in that, There are at least two strain beams (1a), and their axes are arranged orthogonally to each other.

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