A pressure sensor

Abstract

A pressure sensor comprises a housing with an inner cavity and a medium introduction hole; a substrate; a circuit board with a window; a pressure core in the window and electrically connected with the circuit board; a protective cover sealingly fixed to the upper surface of the circuit board, the window upwardly communicates with the interior of the protective cover; a communication pipe integrally extended from the interior of the protective cover to the bottom side, which extends into and sealingly communicates with the medium introduction hole through the window; the interior of the communication pipe communicates with the interior of the protective cover through a communication hole arranged on the side wall of the communication pipe; the window, the interior of the protective cover and the upper part of the communication pipe are filled with protective gel covering the pressure core; only the protective gel contacts the pressure sensing surface of the pressure core, the medium to be measured is limited in the medium introduction hole and the communication pipe, so that the electronic circuit is reliably isolated from the medium to be measured.

Description

Technical Field

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

[0002] When measuring pressure media using a semiconductor pressure core, the medium being measured is often harmful to electronic components and needs to be isolated from them. However, if a large medium pressure needs to be measured simultaneously, the pressure core must be positioned on the side of the substrate closer to the medium being measured. To electrically connect to the pressure core, the circuitry must also be placed on the same side of the substrate, making it difficult to reliably isolate the electronic circuitry from the medium. Regardless of where the pressure core is positioned on the substrate, the gel protecting the pressure core's leads introduces measurement errors due to its own weight while conducting pressure.

[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: The housing has an inner cavity and a medium inlet port for introducing the medium to be tested into the inner cavity; A horizontally extending substrate is disposed within the inner cavity; A horizontally extending circuit board has a window connecting its upper and lower surfaces, the lower surface of which is sealed to the upper surface of the substrate by a ring of first sealant; the first sealant is located around the periphery of the window. A pressure core fixed to the upper surface of the substrate is located within the window and is electrically connected to the circuit board. A protective cover is fixed downwards and sealed to the upper surface of the circuit board, with the window facing upwards and communicating directly into the interior of the protective cover; A connecting tube integrally extends from the inside of the protective cover toward the bottom side, passes through the window toward the bottom side, and extends into and seals the medium inlet hole; its interior is connected to the interior of the protective cover through a connecting hole provided on the side wall of the connecting tube. The interior of the window and the protective cover, as well as the upper part of the connecting tube, are filled with a protective gel covering the pressure core.

[0006] Preferably, the lower surface of the protective gel is flush with or extends downward beyond the upper surface of the substrate.

[0007] Preferably, an annular sealing groove is provided on the lower outer wall of the connecting pipe, and the connecting pipe is sealed to the inner wall of the medium inlet hole by a sealing ring disposed in the annular sealing groove.

[0008] Preferably, the lower edge of the connecting hole is flush with or extends upward beyond the upper surface of the circuit board.

[0009] Preferably, the protective cover includes a cover body and a sealing flange extending downward from the cover body, the lower end of the sealing flange being sealed to the upper surface of the circuit board by a second sealant.

[0010] Preferably, the upper end of the connecting pipe is integrally connected to the cover body.

[0011] Preferably, the upper sidewall of the connecting pipe is integrally connected to the sealing flange in a transverse outward direction.

[0012] Preferably, the housing comprises a lower shell having a recessed cavity with an upper opening and a cover having an upper opening that closes the recessed cavity downwards; the inner cavity is at least partially defined by the recessed cavity.

[0013] Preferably, the lower shell extends integrally downward around the medium inlet hole to form a connector tube, and the internal cross-sectional area of ​​the connector tube is larger than the cross-sectional area of ​​the medium inlet hole.

[0014] Preferably, a connector is integrally connected to one lateral end of the lower shell; multiple conductive pins are fixed on the lower shell, with the top of the conductive pins passing through and electrically connected to multiple conductive holes provided on the circuit board; several of the conductive pins extend outward from inside the lower shell into the connector to form an external part.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention fixes the pressure core to the upper side of the substrate and positions it within a window on the circuit board. Simultaneously, a protective cover seals the upper surface of the circuit board to form an independent chamber. This seals the pressure core and its above-ground electrical connection area within this chamber and the protective gel, isolating it from the lower shell cavity. The test medium enters through a medium inlet hole and a connecting tube, contacting the pressure-sensing surface of the pressure core only through the protective gel. The test medium is confined within the medium inlet hole and the connecting tube, reliably isolating the electronic circuitry from the test medium.

[0016] 2. This invention fills the window, the inside of the protective cover, and the upper part of the connecting tube with protective gel. When the pressure sensor is in normal use, the medium inlet hole faces downward, and the gravity of the protective gel inside the connecting tube generates an upward "negative pressure." This effect is transmitted to the inside of the protective cover through the connecting hole, balancing the positive pressure of the protective gel acting on the upper surface of the pressure core inside the protective cover. This can reduce the error caused by the gravity of the protective gel.

[0017] 3. The connecting tube and protective cover of this invention are integrally formed and extend downward from the inside of the protective cover. After passing through the circuit board window, they are directly and sealed to the medium inlet hole. The structure is compact, and the pressure transmission path is direct and short, reducing the cavity and hysteresis of pressure transmission and improving the dynamic response performance of the sensor. At the same time, the integrated structure reduces the number of assembly parts and sealing interfaces, improving the sealing reliability and long-term stability of the product.

[0018] 4. The circuit board of the present invention is sealed and fixed to the substrate by a first sealant, and the protective cover is sealed and fixed to the circuit board by a second sealant, forming a multi-level sealing barrier, which further ensures the isolation reliability of the pressure core and its electrical connection area from the external environment and the inner cavity of the lower shell, and enhances the environmental adaptability and durability of the sensor. 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. Shell; 11. Lower shell; 111. Cavity; 112. Medium inlet hole; 113. Connector tube; 114. Connector; 12. Cover; 13. Inner cavity; 2. Substrate; 3. Circuit board; 31. Window; 32. Conductive hole; 4. Pressure core; 41. Lead wire; 5. Protective cover; 51. Cover body; 52. Sealing flange; 53. Second sealant; 6. Connecting tube; 61. Connecting hole; 62. Sealing ring; 7. Protective gel; 8. First sealant; 9. Conductive pin; 91. External part. 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 sensing component disposed within the housing 1, and a connector 114 for external electrical connection.

[0025] In this embodiment, the housing 1 includes a lower shell 11 and a cover 12. The lower shell 11 has an upward-opening cavity 111 inside. The shape of the cover 12 is adapted to the upper opening of the lower shell 11 and closes the upper opening of the cavity 111 downward, thereby defining an inner cavity 13 together with the lower shell 11.

[0026] The bottom of the lower shell 11 is provided with a medium inlet hole 112 for introducing the external medium to be tested into the inner cavity 13. Further, the lower shell 11 can extend downward integrally to form a connector tube 113 around the medium inlet hole 112. The internal cross-sectional area of ​​the connector tube 113 is usually larger than the cross-sectional area of ​​the medium inlet hole 112 itself, forming a flared or stepped structure.

[0027] The sensing component is disposed in the inner cavity 13 of the housing 1 and is used to sense the pressure to be measured introduced through the medium inlet hole 112 and convert it into an electrical signal. The sensing component mainly includes a substrate 2, a circuit board 3, a pressure core 4, a protective cover 5, a connecting tube 6, and a protective gel 7.

[0028] The substrate 2 is disposed horizontally within the cavity 13. Exemplarily, the substrate 2 can be made of a material with good thermal conductivity and a certain rigidity, such as a ceramic or metal substrate 2. The substrate 2 can be fixed to the bottom of the recess 111 of the lower shell 11 or to a support structure inside it using adhesive, ensuring its positional stability.

[0029] Circuit board 3 is also horizontally extended and disposed above substrate 2. Circuit board 3 has a window 31 connecting its upper and lower surfaces. The function of window 31 is to provide mounting and pressure-sensing space for pressure core 4. The lower surface of circuit board 3 is sealed and fixed to the upper surface of substrate 2 by a ring of first sealant 8. The first sealant 8 is located around the window 31, isolating the area of ​​window 31 from other areas between substrate 2 and circuit board 3. The first sealant 8 can be epoxy resin, silicone rubber, or other adhesives with good adhesion and sealing properties. Through this sealing and fixing method, a reliable sealed connection is formed between circuit board 3 and substrate 2, preventing media from intruding into the circuit area on the upper surface of circuit board 3 from below.

[0030] The pressure core 4 is fixed to the upper surface of the substrate 2 and is located within the window 31 of the circuit board 3. The pressure core 4 is electrically connected to the circuit board 3 via leads 41, such as gold wires or copper wires, so as to transmit the pressure signal it senses to the processing circuit on the circuit board 3.

[0031] The protective cover 5 is fixedly and sealed to the upper surface of the circuit board 3 with its face downwards. The protective cover 5 can be a cap-shaped or cup-shaped component made of plastic or ceramic. The internal space of the protective cover 5 is directly opposite and communicates with the window 31 of the circuit board 3 with its face upwards.

[0032] The connecting tube 6 is integrally formed from the interior of the protective cover 5, extending towards the bottom (i.e., towards the circuit board 3 and the substrate 2). The connecting tube 6 can be considered as a downwardly extending tubular structure at the bottom of the protective cover 5. The connecting tube 6 passes through the window 31 of the circuit board 3 towards the bottom (downward) and extends further downward, finally sealingly connecting to the medium inlet hole 112 of the lower shell 11. The internal channel of the connecting tube 6 is connected to the internal space of the protective cover 5 through a connecting hole 61 provided on the side wall of the connecting tube 6.

[0033] To ensure a reliable seal between the connecting pipe 6 and the medium inlet hole 112, in a preferred embodiment, an annular sealing groove is provided on the lower outer wall of the connecting pipe 6. A sealing ring 62 (such as an O-ring) is disposed within this annular sealing groove. When the connecting pipe 6 is inserted into the medium inlet hole 112, the sealing ring 62 is compressed between the outer wall of the connecting pipe 6 and the inner wall of the medium inlet hole 112, forming a radial seal.

[0034] The window 31, the internal space of the protective cover 5, and the upper part of the connecting pipe 6 together form a continuous volume. This volume is filled with protective gel 7. The protective gel 7 covers the pressure core 4 and the lead wire 41 above it. The protective gel 7 is preferably a soft, pressure-permeable, and chemically stable gel material, such as silicone gel. It has three functions: first, to protect the pressure core 4 and the fragile lead wire 41 from mechanical damage and environmental influences; second, to serve as a medium for transmitting pressure, transferring the pressure of the medium to be measured to the pressure-sensing surface of the pressure core 4; and third, to assist in fixing the internal components. In this embodiment, in order to fill the window 31, the internal space of the protective cover 5, and the upper part of the connecting pipe 6 with protective gel 7, the bottom end of the connecting pipe 6 can be used as the glue-filling port, and the pressure sensor can be inverted for glue filling.

[0035] In this embodiment, the lower surface of the protective gel 7 is flush with or extends downward beyond the upper surface of the substrate 2, thereby using the negative pressure formed by the gravity of the protective gel 7 in the connecting tube 6 to balance the positive pressure caused by the gravity of the protective gel 7 on the upper side of the pressure chip (not completely or absolutely balanced), which can reduce the error caused by the gravity of the protective gel.

[0036] In this embodiment, the protective cover 5 may include a cover body 51 and a sealing flange 52 extending downward from the edge of the cover body 51. The lower end of the sealing flange 52 is sealed to the upper surface of the circuit board 3 by a ring of second sealant 53 and surrounds the periphery of the window 31. The second sealant 53 may also be epoxy resin or silicone rubber, etc. In this embodiment, the upper end of the connecting pipe 6 may be directly and integrally connected to the top of the cover body 51. As another preferred embodiment, the connecting pipe 6 may also be integrally connected to the inner side of the sealing flange 52 laterally outward through its upper sidewall.

[0037] In this embodiment, a connector 114 is integrally connected to one lateral end of the lower shell 11. A plurality of conductive pins 9 are fixed on the lower shell 11. The tops of these conductive pins 9 pass through the corresponding conductive holes 32 provided on the circuit board 3 and are electrically connected to the circuit on the circuit board 3. The conductive pins 9 extend outward from the inside of the lower shell 11 to form an external part 91, and are embedded or fixed in the connector 114.

[0038] 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: The housing has an inner cavity and a medium inlet port for introducing the medium to be tested into the inner cavity; A horizontally extending substrate is disposed within the inner cavity; A horizontally extending circuit board has a window connecting its upper and lower surfaces, the lower surface of which is sealed to the upper surface of the substrate by a ring of first sealant; the first sealant is located around the periphery of the window. A pressure core fixed to the upper surface of the substrate is located within the window and is electrically connected to the circuit board. A protective cover is fixed downwards and sealed to the upper surface of the circuit board, with the window facing upwards and communicating directly into the interior of the protective cover; A connecting tube integrally formed from the inside of the protective cover extending towards the bottom side passes through the window and extends into and seals the medium inlet hole. Its interior is connected to the interior of the protective cover through a connecting hole provided on the side wall of the connecting pipe; The interior of the window and the protective cover, as well as the upper part of the connecting tube, are filled with a protective gel covering the pressure core.

2. The pressure sensor according to claim 1, characterized in that, The lower surface of the protective gel is flush with or extends downward beyond the upper surface of the substrate.

3. The pressure sensor according to claim 1, characterized in that, An annular sealing groove is provided on the lower outer wall of the connecting pipe, and the connecting pipe is sealed to the inner wall of the medium inlet hole by a sealing ring disposed in the annular sealing groove.

4. The pressure sensor according to claim 1, characterized in that, The lower edge of the connecting hole is flush with or extends upward beyond the upper surface of the circuit board.

5. The pressure sensor according to claim 1, characterized in that, The protective cover includes a cover body and a sealing flange extending downward from the cover body. The lower end of the sealing flange is sealed to the upper surface of the circuit board by a second sealant.

6. The pressure sensor according to claim 5, characterized in that, The upper end of the connecting pipe is integrally connected to the cover body.

7. The pressure sensor according to claim 5, characterized in that, The upper sidewall of the connecting pipe is integrally connected to the sealing flange in a transverse outward direction.

8. The pressure sensor according to claim 1, characterized in that, The housing includes a lower shell having a recessed cavity with an upper opening and a cover having an upper opening that closes the recessed cavity downwards; the inner cavity is at least partially defined by the recessed cavity.

9. The pressure sensor according to claim 8, characterized in that, The lower shell extends integrally downward around the medium inlet hole to form a connector tube, and the internal cross-sectional area of ​​the connector tube is larger than the cross-sectional area of ​​the medium inlet hole.

10. The pressure sensor according to claim 8, characterized in that, A connector is integrally connected to one lateral end of the lower shell; multiple conductive pins are fixed on the lower shell, with the top of the conductive pins pointing upwards and passing through and electrically connected to multiple conductive holes provided on the circuit board; several of the conductive pins extend outwards from inside the lower shell into the connector to form an external part.

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