A pressure sensor

Abstract

A pressure sensor comprises a housing enclosing a mounting cavity, including a main casing and an upper cover; the main casing includes a tube body and a seat body; the upper side surface of the seat body partially defines the mounting cavity and is connected downwardly to the interior of the tube body through a pressure hole; a metal cylinder shell is embedded in the main casing, which presses the upper cover downwardly to the main casing; a base plate is integrally extended inwardly from the lower end of the metal cylinder shell, which closes the pressure hole downwardly and has a transverse mounting plane exposed in the mounting cavity, which is provided with a via hole for connecting the pressure hole upwardly to the transverse mounting plane; a pressure measuring element is closed on the upper end of the via hole; and an electronic module assembly is fixed in the mounting cavity; the base plate is integrally designed with the metal cylinder shell, which is integrally extended inwardly from the lower end of the metal cylinder shell, so that the overall axial height of the pressure sensor is significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically a pressure sensor. Background Technology

[0002] Pressure sensors are used to measure the pressure of media within containers. Their pressure-sensitive element is typically mounted on a circuit board and base plate. The base plate and pressure interface are not integrated; therefore, a reliable seal must be maintained between the base plate and the housing to prevent media leakage. To ensure this seal, a relatively thick base plate is usually required. This base plate is pressed downwards against the housing by the metal casing, and the seal is achieved through two sealing rings, one inner and one outer, positioned between the base plate and the housing. This results in a relatively large sensor height and higher cost.

[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] The purpose of this invention is to provide a pressure sensor to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A pressure sensor, comprising: An outer shell forming an installation cavity includes a main plastic shell and a top cover; the main shell includes a tube extending horizontally and at least one end for introducing the pressure medium to be measured, and a seat formed by the outer wall of the tube protruding upward; the upper surface of the seat partially defines the installation cavity and communicates downward to the interior of the tube through a pressure hole; The lower metal cylindrical shell is embedded in the main housing, which presses the upper cover downwards against the main housing; A base plate integrally extended inward from the lower end of the metal shell has a downward-facing closed pressure hole and a transverse mounting plane exposed in the mounting cavity, on which a through hole is provided to allow the pressure hole to communicate upward to the transverse mounting plane. A pressure measuring element, which is enclosed at the upper end of the through hole; and an electronic module assembly fixed within the mounting cavity, which is electrically connected to the pressure measuring element.

[0006] Preferably, the upper surface of the seat body forms a cavity surrounding the transverse mounting plane, and the cavity is filled with a first sealant that is lower than the transverse mounting plane.

[0007] Preferably, the substrate includes a horizontal plate and a skirt integrally connected to the outer edge of the horizontal plate at its upper end. The lateral mounting plane is defined by the upper surface of the horizontal plate. The skirt extends from the bottom of the cavity and is embedded in the interior of the main housing. The interface between the outer wall of the skirt and the bottom of the cavity is covered by the first sealant. One side edge of the lower end of the skirt integrally extends to the metal shell.

[0008] Preferably, the lower end of the skirt is radially outward relative to the upper end, and one side edge of the lower end of the skirt extends integrally and laterally to the metal shell.

[0009] Preferably, the metal shell and the substrate are integrally pressed together.

[0010] Preferably, a sealing groove is formed between the outer wall of the metal cylinder and the base, and the sealing groove is filled with a second sealant.

[0011] Preferably, the upper end of the metal shell is rolled inward to form a pressing edge, and the pressing edge presses the upper cover tightly against the base body.

[0012] Preferably, the pressing edge forms a complete circle on the transverse plane, and a sealing ring is used to seal the pressing edge and the upper cover.

[0013] Preferably, the electronic module assembly includes a laterally extending circuit board and a processing circuit fixed to the upper surface of the circuit board and electrically connected to the pressure measuring element. The lower surface of the circuit board is sealed to the upper surface of the base by a third sealant. The circuit board is provided with a window for accommodating the pressure measuring element.

[0014] Preferably, the upper cover is provided with a plurality of pins, one end of the pin is located outside the mounting cavity, and the other end passes through the upper cover and extends into the mounting cavity. The end of the pin located in the mounting cavity is electrically connected to the electronic module assembly.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention eliminates the need for a separate substrate component, integrating the substrate function with the metal casing in a single design. The substrate is formed by an integral inward extension from the lower end of the metal casing. This significantly reduces the number of sensor components, simplifies the assembly process, and directly lowers material and assembly costs.

[0016] 2. By eliminating the need for a thicker independent substrate and the double sealing ring structure required to seal the substrate, the overall axial height of the pressure sensor is significantly reduced, resulting in a more compact structure that is more suitable for applications with limited installation space.

[0017] 3. This invention utilizes a first sealant to fill the joint interface between the substrate and the main housing, thereby strengthening the seal at the joint interface and preventing the risk of seal failure due to penetration of the pressure medium under temperature changes. This sealing method provides excellent sealing performance, further reduces the axial height of the pressure sensor, and avoids the risk of seal ring failure at low temperatures.

[0018] 4. By setting a second sealant, the annular joint interface between the outer wall of the metal cylinder and the seat can be strengthened to prevent the risk of the pressure medium to be tested from seeping in under conditions such as temperature changes. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the pressure sensor structure in this embodiment; Figure 2 for Figure 1 Enlarged view of a portion of point A in the middle; In the diagram: 1. Outer shell; 11. Main shell; 111. Tube body; 112. Seat body; 1121. Upper surface; 1122. Pressure hole; 1123. Cavity; 12. Top cover; 121. Pin; 122. Sealing ring; 2. Metal cylinder shell; 21. Pressing edge; 3. Base plate; 31. Horizontal plate; 311. Horizontal mounting plane; 312. Through hole; 32. Skirt; 4. Pressure measuring element; 5. Electronic module assembly; 51. Circuit board; 511. Window; 512. Third sealant; 52. Processing circuit; 53. Connecting plate; 6. First sealant; 7. Second sealant; 8. Upper reinforcing plate; 9. Upper circuit board. Detailed Implementation

[0020] 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.

[0021] 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," and "third," etc., are only used for the purpose of distinguishing the modified objects, and should not be construed as indicating or implying relative importance.

[0022] 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.

[0023] 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 and all possible combinations.

[0024] like Figure 1 and Figure 2 As shown, this embodiment provides a pressure sensor, including a housing 1, a metal cylindrical shell 2, a substrate 3, a pressure measuring element 4, and an electronic module assembly 5.

[0025] The outer casing 1 encloses a sealed mounting cavity, providing protection for the internal components. The outer casing 1 includes a main housing 11 and a top cover 12 made of plastic. The main housing 11 is preferably integrally molded using an injection molding process, and its material can be engineering plastics with good mechanical strength, dimensional stability, and chemical resistance, such as PPS (polyphenylene sulfide), PBT (polybutylene terephthalate), and PA (nylon). The main housing 11 includes a horizontally extending tube 111. At least one end of the tube 111 is open for introducing the pressure medium to be measured. Exemplarily, the tube 111 may have one blind end and the other a threaded connection interface; or both ends may be connection interfaces. A body 112 protrudes upwards (i.e., away from the axis of the tube 111) from the outer wall of the tube 111. The upper surface 1121 of the body 112 partially defines the bottom contour of the mounting cavity. A pressure hole 1122 is provided in the central region of the base 112. The pressure hole 1122 extends downward (i.e., toward the interior of the tube 111), so that the internal space of the tube 111 is connected to the mounting cavity on the upper side of the base 112. After the pressure medium to be measured is introduced through the tube 111, it can be transmitted to the mounting cavity through this pressure hole 1122.

[0026] The metal shell 2 is made of metal, such as stainless steel, copper alloy, or aluminum alloy, and its lower part is embedded in the seat 112 of the main shell 11 during assembly. A key function of the metal shell 2 is to provide axial clamping force. Specifically, the upper end of the metal shell 2 is pressed down on the upper cover 12 (i.e., towards the seat 112 of the main shell 11) by a structure, thereby clamping and fixing the upper cover 12 together with the main shell 11, forming the top sealing boundary of the mounting cavity.

[0027] The substrate 3 is integrally formed by extending inward from the lower end of the metal shell 2 (i.e., towards the axis of the pressure hole 1122). The substrate 3 has multiple functions: firstly, its downward-facing position closes the upper port of the pressure hole 1122. Secondly, the substrate 3 has a transverse mounting plane 311 exposed within the mounting cavity C. At least one through hole 312 is formed on this transverse mounting plane 311, allowing the lower pressure hole 1122 to communicate upwards with the transverse mounting plane 311. The integrated design of the substrate 3 and the metal shell 2 simplifies the structure and reduces the number of parts.

[0028] Exemplary examples show that the metal shell 2 and the substrate 3 can be manufactured using various integral forming processes. For instance, they can be manufactured using metal cold heading, stamping, and stretching integral forming processes. Specifically, a metal sheet is selected, and through multiple stamping and stretching processes, a cylindrical metal shell 2 and a substrate 3 extending inward from its bottom are formed simultaneously. Alternatively, they can be integrally formed using metal casting (such as precision casting). Preferably, the metal shell 2 and the substrate 3 are integrally pressed, which provides high production efficiency, the best connection strength, and eliminates the potential corrosion or fatigue risks associated with weld seams.

[0029] The pressure measuring element 4 is fixed on the transverse mounting plane 311 of the substrate 3, and the upper end of the through hole 312 is sealed. The pressure measuring element 4 is used to sense the medium pressure transmitted through the pressure hole 1122 and the through hole 312, and convert it into an electrical signal. The pressure measuring element 4 is fixed on the transverse mounting plane 311 by means of bonding, welding or glass micro-melting, and the through hole 312 is completely covered and sealed to ensure that the pressure medium acts only on its pressure-sensing diaphragm.

[0030] The electronic module assembly 5 is fixed within the mounting cavity and electrically connected to the pressure measuring element 4. The electronic module assembly 5 processes the electrical signals output by the pressure measuring element 4. The electrical connection between the pressure measuring element 4 and the electronic module assembly 5 can be achieved through wire bonding or flip-chip bonding, among other methods.

[0031] To ensure a reliable seal between the substrate 3, which is integrally extended from the metal shell 2, and the plastic main shell 11, and to prevent the pressure medium from leaking from their contact interface to other parts of the mounting cavity, this invention employs a sealant filling scheme. In a preferred embodiment, the upper surface 1121 of the seat 112 forms a recess 1123 surrounding the transverse mounting plane 311. This recess 1123 can be an annular groove, with its bottom lower than the transverse mounting plane 311. The recess 1123 is filled with a first sealant 6, and the filling amount is controlled so that the upper surface of the first sealant 6 is lower than the transverse mounting plane 311. After the first sealant 6 is filled and cured, it can completely fill the interface between the edge of the substrate 3 and the bottom and sidewalls of the recess 1123, forming a continuous sealing barrier. Compared with traditional O-ring seals, this design has lower requirements for part machining tolerances and assembly alignment, higher sealing reliability, and the first sealant 6 can also play a role in bonding, fixing, and buffering stress. For example, the first sealant 6 may be epoxy resin sealant, silicone rubber, polyurethane sealant or anaerobic adhesive, etc. When selecting, its adhesion to metals and plastics, flexibility, resistance to media and temperature resistance should be considered.

[0032] Furthermore, to enhance the structural stability of the substrate 3 within the main housing 11 and the length of the sealing path, the substrate 3 can be designed to include a horizontal plate 31 and a skirt 32. The horizontal plate 31, which bears the pressure measuring element 4, extends upwards to form the transverse mounting plane 311. The upper end of the skirt 32 is integrally connected to the outer edge (i.e., the edge in the circumferential direction) of the horizontal plate 31 and extends downwards. In the assembled state, the skirt 32 extends downwards from the bottom of the cavity 1123 and is embedded in the internal plastic body of the main housing 11. The annular joint interface between the outer wall of the skirt 32 and the bottom of the cavity 1123 is precisely covered and sealed by the first sealant 6. By providing the skirt 32, the contact area and interlocking depth between the metal and the plastic are increased, improving the bonding strength. One side edge of the lower end of the skirt 32 integrally extends to the lower end of the metal shell 2, thus structurally completing the transition from the metal shell 2 to the horizontal plate 31.

[0033] As an optimized form of the skirt 32, the lower end of the skirt 32 can be inclined radially outward relative to its upper end. One side edge of the lower end of the skirt 32 extends integrally and laterally to the metal shell 2, forming a stable support and force transmission structure.

[0034] A sealing groove is formed between the outer wall of the metal shell 2 and the inner wall of the base 112, and the sealing groove is filled with a second sealant 7. The second sealant 7 forms a second sealing barrier between the outer wall of the metal shell 2 and the plastic base 112, mainly preventing moisture, dust or other pollutants from the external environment from entering the mounting cavity from the top of the sensor along the outer wall of the metal shell 2. Exemplarily, the second sealant 7 can be the same as or different from the first sealant 6, commonly silicone rubber or polyurethane sealant, requiring good elasticity and aging resistance.

[0035] Preferably, the upper end of the metal shell 2 is rolled inward to form a pressing edge 21, and the pressing edge 21 presses the upper cover 12 against the seat body 112 with the lower end facing downward. The pressing edge 21 forms a complete circle on the transverse plane, and a sealing ring 122 forms a seal between the pressing edge 21 and the upper cover 12.

[0036] In one embodiment, the electronic module assembly 5 includes a laterally extending circuit board 51. Processing circuitry 52 is integrated or soldered onto the circuit board 51 and is electrically connected to the pressure measuring element 4. A window 511 is provided on the circuit board 51 to mount the pressure measuring element 4 and allow its signal to be output. The pressure measuring element 4 is located within this window 511, and leads for electrical connection between the pressure measuring element 4 and the circuit board 51 are connected to wiring on the circuit board 51 through the window 511. The lower surface of the circuit board 51 is sealed to the upper surface 1121 of the housing 112 using a third sealant 512.

[0037] A plurality of pins 121 are fixed on the upper cover 12. One end (outer end) of the pin 121 is located outside the mounting cavity and is used to connect external cables or connectors; the other end (inner end) is sealed through the upper cover 12 and extends into the mounting cavity. The inner end of the pin 121 is electrically connected to the electronic module assembly 5, thereby realizing signal input and output.

[0038] In this embodiment, an upper reinforcing plate 8 is fixed to one inner end of the pin 121. The upper reinforcing plate 8 can be made of metal or rigid plastic, and its function is to strengthen the mechanical strength of the root of the pin 121 and prevent it from breaking or loosening under vibration. An upper circuit board 9 is fixed to the surface of the upper reinforcing plate 8 facing the circuit board 51. The upper circuit board 9 is electrically connected to the circuit board 51 below it through a connecting plate 53. The circuit board 51, the upper circuit board 9, and the connecting plate 53 can all be made of flexible printed circuit board (FPC).

[0039] It should be noted that although the present invention has been disclosed above with specific embodiments, the above embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A pressure sensor, characterized in that, include: An outer shell forming an installation cavity includes a main plastic shell and a top cover; the main shell includes a tube extending horizontally and at least one end for introducing the pressure medium to be measured, and a seat formed by the outer wall of the tube protruding upward; the upper surface of the seat partially defines the installation cavity and communicates downward to the interior of the tube through a pressure hole; The lower metal cylindrical shell is embedded in the main housing, which presses the upper cover downwards against the main housing; A base plate integrally extended inward from the lower end of the metal shell has a downward-facing closed pressure hole and a transverse mounting plane exposed in the mounting cavity, on which a through hole is provided to allow the pressure hole to communicate upward to the transverse mounting plane. A pressure measuring element, which is enclosed at the upper end of the through hole; and an electronic module assembly fixed within the mounting cavity, which is electrically connected to the pressure measuring element.

2. The pressure sensor according to claim 1, characterized in that, The upper surface of the seat forms a cavity surrounding the transverse mounting plane, and the cavity is filled with a first sealant that is lower than the transverse mounting plane.

3. The pressure sensor according to claim 2, characterized in that, The substrate includes a horizontal plate and a skirt integrally connected to the outer edge of the horizontal plate at its upper end. The horizontal mounting plane is defined by the upper surface of the horizontal plate. The skirt extends from the bottom of the cavity and is embedded in the interior of the main housing. The interface between the outer wall of the skirt and the bottom of the cavity is covered by the first sealant. One side edge of the lower end of the skirt integrally extends to the metal shell.

4. The pressure sensor according to claim 3, characterized in that, The lower end of the skirt slopes radially outward relative to the upper end, and one side edge of the lower end of the skirt extends integrally and laterally into the metal shell.

5. The pressure sensor according to claim 1, characterized in that, The metal shell and the substrate are integrally pressed together.

6. The pressure sensor according to claim 1, characterized in that, A sealing groove is formed between the outer wall of the metal cylinder and the base, and the sealing groove is filled with a second sealant.

7. The pressure sensor according to claim 1, characterized in that, The upper end of the metal shell is rolled inward to form a pressing edge, and the pressing edge presses the upper cover tightly against the base.

8. The pressure sensor according to claim 7, characterized in that, The pressing edge forms a complete circle on the transverse plane, and a sealing ring is used to seal the pressing edge and the upper cover.

9. The pressure sensor according to claim 1, characterized in that, The electronic module assembly includes a laterally extending circuit board and a processing circuit fixed to the upper surface of the circuit board and electrically connected to the pressure measuring element. The lower surface of the circuit board is sealed to the upper surface of the base by a third sealant. The circuit board has a window for accommodating the pressure measuring element.

10. The pressure sensor according to claim 1, characterized in that, The top cover is provided with a plurality of pins, one end of which is located outside the mounting cavity, and the other end passes through the top cover and extends into the mounting cavity. The end of the pin located in the mounting cavity is electrically connected to the electronic module assembly.

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