Compressible element for a sensor assembly - Patents.com

Abstract

To provide a compressible element for a sensor assembly capable of preventing damage to a sensor element even if liquid periodically repeats freezing and thawing.SOLUTION: A compressible element 200 for a sensor assembly 10 includes an elastomer matrix 210 having first compressibility and a plurality of closed areas 220 distributed within the elastomer matrix 210 and each surrounded by the elastomer matrix 210. Each of the plurality of closed areas 220 has second compressibility greater than the first compressibility.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sensor assembly, and more particularly to a compressible element for a sensor assembly. [Background technology]

[0002] Some sensor or transducer assemblies have a sensing element and a compressible plug disposed within the structure of the sensor assembly. This type of pressure sensor assembly is positioned, for example, within a bath containing a fluid. The fluid surrounds the compressible plug and contacts the sensing element to detect the level and flow rate of the fluid. The fluid may freeze under certain environmental conditions, causing the fluid to expand significantly. The compressible plug compensates for volumetric variations of the surrounding fluid to protect the sensing element from damage. Summary of the Invention [Problem to be solved by the invention]

[0003] Compressible plugs for sensor assemblies are typically made from solid elastomers, which in many applications do not provide sufficient compressibility to compensate for volumetric variations. For compressible plugs formed from more compressible porous closed-cell elastomers, the pore structure of the closed-cell elastomer material is difficult to control, resulting in uneven pore distribution and thin and weak walls between the pores. In addition, the closed-cell elastomer material is often cut from the formed material, exposing pores at the cut edges, which allow liquid to penetrate the compressible plug. The weak pore structure and liquid infiltration can make the compressible plug mechanically weak and unable to maintain the required compressibility through cyclic freezing and thawing, which can lead to damage to the sensor element. [Means for solving the problem]

[0004] A compressible element for a sensor assembly includes an elastomeric matrix having a first compressibility and a plurality of closed areas dispersed within and surrounded by the elastomeric matrix, each of the plurality of closed areas having a second compressibility greater than the first compressibility.

[0005] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a cross-sectional side view of a sensor assembly according to one embodiment. [Figure 2A] FIG. 2 illustrates a cross-sectional perspective view of a compressible element according to one embodiment. [Figure 2B] FIG. 13 is a perspective view of an outer shell of a compressible element according to another embodiment. [Figure 2C] FIG. 13 is a perspective view of a compressible element according to another embodiment. [Figure 3A] FIG. 13 is a cross-sectional side view of a compressible element according to another embodiment. [Figure 3B] FIG. 13 is a cross-sectional side view of a compressible element according to another embodiment. [Figure 4] FIG. 13 is a schematic diagram of a sensor assembly according to another embodiment. [Diagram 5] FIG. 13 is a schematic diagram of a sensor assembly according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same reference numbers refer to similar elements. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that the present disclosure can convey the concept of the present disclosure to those skilled in the art. In addition, in the following detailed description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it is clear that one or more embodiments can be implemented without these specific details.

[0008] A sensor assembly 10 according to one embodiment is shown in Figure 1. The sensor assembly 10 comprises a cavity structure 100, a compressible element 200 disposed within the cavity structure 100, a sensor element 300 disposed within the cavity structure 100, and a ledge adapter 400 attached to the cavity structure 100.

[0009] The cavity structure 100 includes a cavity 110 defined by an inner surface 120 and a cavity wall 130, as shown in Figure 1. The inner surface 120 is positioned at an inner end 112 of the cavity 110, and an outer end 114 of the cavity 110 opposite the inner end 112 opens to an area A outside the cavity structure 100. In the illustrated embodiment, the cavity 110 is cylindrical. In other embodiments, the cavity 110 may be a rectangular prism or any other shape capable of receiving the compressible element 200 and the sensor element 300. The cavity 110 has a cavity width 116 in a width direction W.

[0010] 1-3B, includes an elastomeric matrix 210, a plurality of closed regions 220 dispersed within and each surrounded by elastomeric matrix 210, and passages 240 extending through elastomeric matrix 210. Elastomeric matrix 210 has a first compressibility, and each of closed regions 220 has a second compressibility greater than the first compressibility.

[0011] The compressible element 200 has an interior side 212, an exterior side 214 opposite the interior side 212, and a plurality of lateral sides 216 connecting the interior side 212 to the exterior side 214, as shown in Figures 1-3B. Between the sides 216, the compressible element 200 has an elastomer width 218 in a width direction W, as shown in Figure 1, and an elastomer length 219 in a length direction L perpendicular to the width direction W. In the illustrated embodiment, the compressible element 200 has a cylindrical shape corresponding to the cavity 110. In other embodiments, the elastomeric matrix 210 can be a rectangular prism or any other shape corresponding to the shape of the cavity 110.

[0012] In various embodiments, elastomeric matrix 210 can be formed from silicone, fluorosilicone, epoxy, or any other elastomeric material. The hardness of elastomeric matrix 210 can be selected based on the application, with a harder elastomeric matrix 210 having a higher resilience to high pressure environments and a softer elastomeric matrix 210 being better suited for compressibility. Elastomeric matrix 210 has a chemical compatibility appropriate for the application. For example, in embodiments in which elastomeric matrix 210 is exposed to diesel exhaust fluid (DEF), as described below, elastomeric matrix 210 is selected to avoid degradation under DEF exposure.

[0013] 1-3B, compressible element 200 includes only closed regions 220, and none of the regions in elastomeric matrix 210 having the second compressible property are open to faces 212, 214, 216 of compressible element 200. The exposed surface of each face 212, 214, 216 of elastomeric matrix 210 is a continuous, uninterrupted elastomeric material.

[0014] Each closed region 220 can be a hollow void having a second compressibility, or each can be filled with a solid material having a second compressibility. The size of each closed region 220 can be selected depending on the application, with larger closed regions 220 increasing the compressibility of the compressible element 200 and smaller closed regions 220 increasing the strength and having a higher resilience to high pressure environments. In the embodiment of Figures 1-2B, the closed regions 220 are distributed within the elastomeric matrix 210 such that the thickness 222 of the elastomeric matrix 210 disposed between each closed region 220 and its nearest adjacent closed region 220 is approximately the same.

[0015] 1 and 2A , the passageway 240 extends in an axial direction P through the elastomeric matrix 210 from the inner surface 212 to the outer surface 214. In the illustrated embodiment, the passageway 240 is approximately centrally positioned within the elastomeric matrix 210. In other embodiments, the passageway 240 may be positioned off-center within the elastomeric matrix 210.

[0016] The particular embodiments of the compressible elements 200 shown in Figures 1-3B will now be individually described in more detail.

[0017] In the embodiment of compressible element 200 shown in Figure 1, each of the closed regions 220 is formed by a polymeric microsphere 224. The compressible element 200 is formed by mixing a plurality of polymeric microspheres 224 into the uncured liquid elastomer of the elastomeric matrix 210, pouring the mixture into a mold or cavity 110, and allowing the mixture to cure. This process results in a uniform thickness 222 between the closed regions 220 described above and shown in Figure 1.

[0018] The polymeric microspheres 224 forming the closed region 220 can be hollow or solid. The weight percentage of the polymeric microspheres 224 compared to the uncured liquid elastomer is selected to affect the compressibility of the compressible element 200. In one embodiment, the hollow polymeric microspheres 224 are incorporated at 0-4% by weight of the uncured liquid elastomer of the elastomeric matrix 210. The size of each polymeric microsphere 224 is also selected to affect the compressibility of the compressible element 200. In one embodiment, the diameter of each polymeric microsphere 224 is less than 200 μm.

[0019] Another embodiment of the compressible element 200 is formed with closed regions 220 as a plurality of contained volumes 226 defined by the elastomeric matrix 210, as shown in Figures 2A-2C. The contained volumes 226 are hollow voids within the elastomeric matrix 210. In the embodiment shown in Figures 2A and 2B, the contained volumes 226 are each formed as a polyhedron, e.g., having a triangular shape or forming a trapezoidal wheel pattern. In other embodiments, the contained volumes 226 can have an annular shape, as shown in Figure 2C, a spherical shape, a cylindrical shape, or any other three-dimensional shape. In one embodiment, the contained volumes 226 can be connected to each other to form a continuous closed region 220 surrounded by the elastomeric matrix 210, as shown in Figures 2B and 2C. The shape of the containing volumes 226, the total volume of the containing volumes 226, the size of each containing volume 226, and the thickness of the elastomeric matrix 210 between the containing volumes 226 can be adjusted and selected depending on the balance of compressibility and mechanical strength desired for a particular application.

[0020] In one embodiment, the compressible element 200 is made by attaching a first shell 227 shown in FIG. 2B to an identical second shell 227. Each shell 227 forms one half of the compressible element 200. To attach the shells 227 to one another, an adhesive 229 is applied to the mating surface 228 of each shell 227, and the mating surfaces 228 are arranged to abut one another along a mating plane M shown in FIG. 2A to define a plurality of contained volumes 226. In one embodiment, the adhesive 229 is an uncured elastomer formed from the same material as the elastomeric matrix 210. In other embodiments, the adhesive 229 can be an adhesive or glue layer. In another embodiment, instead of forming each shell 227 as one half of the compressible element 200, the compressible element 200 can be formed as a cap that is attached to the remainder of the compressible element 200.

[0021] 2A and 2B, the shell 227 or other portions of the compressible element 200 can be formed in a mold, or in another embodiment, the shell 227 or other portions of the compressible element 200 can be formed by 3D printing or additive manufacturing of the material of the elastomeric matrix 210. The 3D printing can be material jetting, material extrusion, stereolithography, or digital light processing type 3D printing.

[0022] In another embodiment, drainage holes 225 can be 3D printed throughout compressible element 200 shown in Figure 2A, as shown in Figure 2C, provided that containing volumes 226 are connected to one another, and uncured material occupying containing volumes 226 can then be drained from compressible element 200 through drainage holes 225. Drainage holes 225 are then filled with uncured elastomer, which in one embodiment is the same material as elastomeric matrix 210, which is cured to close containing volumes 226.

[0023] Another embodiment of a compressible element 200 is shown in Figures 3A and 3B, which are shown in cross section without intersecting passageway 240. Although passageway 240 is not shown, passageway 240 is still present in the embodiment shown in Figures 3A and 3B as well as in the embodiment of Figures 1-2C.

[0024] As shown in Figures 3A and 3B, the compressible element 200 includes a base matrix 230 formed from an elastomeric matrix 210 with a plurality of cells 234 disposed within the base matrix 230. The cells 234 are hollow voids. In the illustrated embodiment, the cells 234 are of various sizes, various shapes, and have various thicknesses of the base matrix 230 between one of the cells 234 and its nearest neighboring cell 234. The base matrix 230 has a pair of faces 236. At least some of the cells 234 are open areas at the faces 236 of the base matrix 230. In one embodiment, the base matrix 230 is formed by cutting a portion from a porous closed cell elastomer.

[0025] 3A and 3B includes a sealing layer 232 disposed about a base matrix 230. The sealing layer 232 closes the cells 234 exposed at face 236 and defines all of the cells 234 as a closed region 220. The sealing layer 232 is formed from an elastomeric material. In one embodiment, the elastomeric material of the sealing layer 232 can be selected for chemical compatibility.

[0026] In the embodiment shown in Figure 3A, the sealing layer 232 is attached to a surface 236 of the base matrix 230. The sealing layer 232 can be attached, for example, by wrapping the uncured sealing layer 232 around the base matrix 230 and then curing the sealing layer 232, as shown in the embodiment of Figure 3A.

[0027] In the embodiment shown in Figure 3B, the sealing layer 232 is attached to the entire periphery of the base matrix 230, including surface 236. The sealing layer 232 can be attached, for example, by encapsulating the base matrix 230 with the uncured sealing layer 232 in a mold and then curing the sealing layer 232, as shown in the embodiment of Figure 3B.

[0028] As shown in Figures 1, 4 and 5, the sensor assembly 10 is assembled with the compressible element 200 and the sensor element 300 disposed within the cavity structure 100. The sensor element 300 is positioned at the inner end 112 of the cavity 110 along the inner surface 120 of the cavity structure 100. A ledge adapter 400 is attached to the cavity structure 100 such that it at least partially covers the outer end 114 of the cavity 110. The ledge adapter 400 can be attached to the cavity structure 100 by welding or any other type of fastening.

[0029] The compressible element 200 according to the embodiment shown in Figures 1-3B is positioned within the cavity 110 and is held and constrained in the length direction L within a portion 118 of the cavity 110 separated from the sensor element 300 by a sensor gap 119, as shown in Figures 4 and 5. In various embodiments, for example, the sensor gap 119 is at least 10 mm, and in other embodiments, at least 30 mm. The portion 118 and the sensor gap 119 are also present in the embodiment of the sensor assembly 10 shown in Figure 1, but for ease of understanding the drawings, the portion 118 and the sensor gap 119 are shown only in the schematic diagrams of Figures 4 and 5.

[0030] 1, the compressible element 200 is held within the cavity 110 by an interference fit with the cavity structure 100. The elastomer width 218 is greater than the cavity width 116 in the width direction W when the compressible element 200 is in an uncompressed state. In one embodiment, the elastomer width 218 is at least 6% greater than the cavity width 116.

[0031] When the compressible element 200 is inserted into the cavity 110, the compressible element 200 is compressed in a width direction W by the cavity wall 130 into a compressed state. As a result of the compression of the compressible element 200, a radial force FR is exerted by the compressible element 200 outward in the width direction W on the cavity wall 130. The radial force FR increases friction between the compressible element 200 and the cavity wall 130 in the length direction L, constraining the compressible element 200 within a portion 118 separated from the sensor element 300 by a sensor gap 119.

[0032] Other embodiments for confining compressible element 200 within portion 118 of cavity 110 are shown in Figures 4 and 5. In each of the embodiments of Figures 4 and 5, compressible element 200 is shown generally in cross section not intersecting passageway 240, although passageway 240 is still present in the embodiment shown in Figures 4 and 5 as well as in the embodiment of Figures 1-2C.

[0033] In the embodiment shown in FIG. 4, the sensor assembly 10 includes a stopper 500 disposed within the cavity 110. The stopper 500 is positioned on the cavity wall 130 within the sensor gap 119 and projects into the cavity 110 in the width direction W. The stopper 500 is a physical barrier that prevents the compressible element 200 from moving into the sensor gap 119 along the length direction L, thereby maintaining the sensor gap 119 between the sensor element 300 and the compressible element 200. In various embodiments, the sensor assembly 10 can include a single stopper 500 disposed on a portion of the cavity wall 130 and extending around the entire cavity wall 130, or can include multiple stoppers 500 disposed on the cavity wall 130. The compressible element 200 shown with the stopper 500 in the embodiment of FIG. 4 can also be further interference-fitted into the cavity structure 100 as described above with reference to FIG. 1.

[0034] In the embodiment shown in FIG. 5, the compressible element 200 is attached to a surface 410 of the ledge adapter 400 facing the cavity 110. In one embodiment, the compressible element 200 can be deposited in an uncured state on the surface 410 and cured on the surface 410. In another embodiment, vinyl silane is first disposed on the surface 410, and then the uncured compressible element 200 is deposited on the surface 410 and cured. Curing the compressible element 200 on the surface 410 forms a bond between the compressible element 200 and the ledge adapter 400, confining the compressible element 200 within the portion 118 of the cavity 110 and preventing the compressible element 200 from moving along the length direction L into the sensor gap 119. The embodiment shown in FIG. 5 can be optionally combined with either or both of the above-described embodiments shown in FIG. 1 and FIG. 4.

[0035] An exemplary use of the sensor assembly 10 will now be described with reference to Figure 1. In the embodiment shown in Figure 1, the sensor assembly 10 includes a housing 600 to which a cavity structure 100 is attached. In the illustrated embodiment, the sensor assembly 10 is a pressure sensor assembly, and the housing 600 is attached to a tank T. An area A outside the cavity structure 100 is disposed in the tank T and filled with a fluid, for example, DEF.

[0036] 1, fluid in region A flows into cavity 110 and through passageway 240 into contact with sensor element 300. Sensor element 300 in contact with the fluid measures the fluid level and pressure in reservoir T. The fluid contacts at least inner surface 212 of compressible element 200, and in the illustrated embodiment, outer surface 214. Under certain conditions the fluid freezes, causing the fluid to expand.

[0037] The compressible element 200 compresses when the fluid freezes, compensating for the increase in volume of the fluid to avoid damage to the sensor element 300. The compensation volume of the compressible element 200 can be selected for a particular application and depends on the compressibility of the compressible element 200 and the total volume of the compressible element 200. The compressibility of the compressible element 200 is determined by the hardness of the elastomeric matrix 210 and the selection of the size and total volume of the closed region 220, as described above. The volume of the compressible element 200 is determined by the elastomer width 218 and the elastomer length 219. The compensation volume required to determine the compressibility and volume selection of the compressible element 200 is determined based on the expected volumetric variation of the fluid.

[0038] In other embodiments, the sensor assembly 10 may be used with fluids other than DEF and may be used to measure fluid properties other than pressure, such as the temperature of the fluid. The sensor assembly 10 may be used in any application where volume compensation is required to protect the sensor element 300.

[0039] The sensor assembly 10 of the embodiments of the invention described herein includes a compressible element 200 to provide volume compensation to protect the sensor element 300. The elastomeric matrix 210 of the compressible element 200 includes only closed regions 220 that are uniformly spaced apart from one another. The compressible element 200 is thus resilient and resilient due to its fluid-tight and mechanically strong internal structure. Furthermore, restricting the compressible element 200 within a portion 118 spaced apart from the sensor element 300 by the sensor gap 119 improves the accuracy and reliability of the sensor element 300 by preventing the compressible element 200 from contacting the sensor element 300.

Claims

1. A compressible element (200) for a sensor assembly (10), comprising: - a first compressible elastomeric matrix (210); - dispersed within said elastomeric matrix (210), a plurality of closed regions (220) surrounded by a matrix (210); Each of the plurality of closed regions (220) has a second compressibility greater than the first compressibility, and The compressible element (200) has a passageway (240) extending through the elastomeric matrix (210); the passage (240) passes through the compressible element (200) in a thickness direction of the compressible element (200); The passage (240) is configured as a flow path for a fluid to be detected by the sensor assembly (10). A compressible element (200).

2. the elastomeric matrix (210) has no open regions within the elastomeric matrix (210) on faces (212, 214, 216) of the elastomeric matrix (210); The compressible element (200) of claim 1.

3. Each of the multiple closed regions (220) is a hollow space. The compressible element (200) of claim 1.

4. Each of the plurality of closed regions (220) is formed by polymer microspheres (224). The compressible element (200) of claim 1.

5. each of the plurality of closed regions (220) is filled with a solid material having the second compressibility; The compressible element (200) of claim 1.

6. The passageway (240) extends through the elastomeric matrix (210) from an inner surface (212) of the elastomeric matrix (210) to an outer surface (214) of the elastomeric matrix (210). The compressible element (200) of claim 1.

7. the thickness (222) of the elastomeric matrix (210) disposed between each of the closed regions (220) and the nearest adjacent closed region (220) is approximately the same; The compressible element (200) of claim 1.

8. The elastomeric matrix (210) is configured to define the plurality of closed regions (220), a first shell (227), - a second shell (227) identical to said first shell (227), - an adhesive (229) attaching said first shell (227) to said second shell (227); ), including The compressible element (200) of claim 1.

9. The elastomeric matrix (210) comprises: a base matrix (230), a sealing layer (232) disposed around said base matrix (230); 、 the base matrix (230) has a plurality of cells (234) disposed within the base matrix (230), at least one of the plurality of cells (234) being open at a face (236) of the base matrix (230); the sealing layer (232) is disposed on the base matrix (230) so as to define the plurality of cells (234) as the plurality of closed regions (220); The compressible element (200) of claim 1.

10. A sensor assembly (10), comprising: - a cavity structure (100) defining a cavity (110) having an inner surface (120); - a sensor element (300) positioned on said inner surface (120) of said cavity structure (100); a compressible element (200) positioned within said cavity (110) and confined within a portion (118) of said cavity (110) separated from said sensor element (300) by a sensor gap (119) which is an air gap; In addition to providing The compressible element (200) has a passage (240) passing through the compressible element (200) in a thickness direction of the compressible element (200); the passage (240) communicates with the sensor gap (119); The passage (240) is configured as a flow path for a fluid to be detected by the sensor element (300). A sensor assembly (10).

11. the compressible element (200) has, in an uncompressed state, an elastomeric width (218) that is greater than a cavity width (116) of the cavity (110); the compressible element (200) is positioned in the cavity (110) in a compressed state and exerts a radial force (FR) on a cavity wall (130) of the cavity structure (100); The sensor assembly (10) of claim 10.

12. Further comprising a ledge adapter (400) attached to the cavity structure (100); the ledge adapter (400) extends over at least a portion of the outer end (114) of the cavity (110) opposite the inner surface (120); the compressible element (200) is attached to a surface (410) of the ledge adapter (400) facing towards the cavity (110); The sensor assembly (10) of claim 10.

13. a stopper (500) disposed within the sensor gap (119), the stopper (500) preventing the compressible element (200) from moving into the sensor gap (119); The sensor assembly (10) of claim 10.

14. The compressible element (200) comprises: - a first compressible elastomeric matrix (210); - a plurality of closed regions (220) dispersed within said elastomeric matrix (210), each of said closed regions being surrounded by said elastomeric matrix (210); each of the plurality of closed regions (220) has a second compressibility greater than the first compressibility; The sensor assembly (10) of claim 10.

15. The compressible element according to claim 1, wherein the passage (240) extends through the elastomeric matrix (210) of the compressible element (200); The passage (240) communicates with the sensor gap (119). The sensor assembly (10) of claim 14.

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