Pressure transmitter

Abstract

The present invention provides a pressure transmitter, wherein the shell of the pressure transmitter is integrally connected with a plastic socket by injection molding, a receiving cavity is formed inside the shell, a sealing groove is provided at the connection transition position between the plastic socket and the inner wall surface of the shell, a sealing ring is embedded in the sealing groove, a pressing piece is provided in the receiving cavity, the pressing piece and the plastic socket are tightly connected by a hot air cold riveting process, and the pressing piece presses the sealing ring in the sealing groove, so that when the pressure transmitter is applied to a vibration condition, the pressing piece can still be kept in a state of pressing the sealing ring. The compression amount of the sealing ring is greater than the volume deformation amount of the sealing ring itself and its surrounding components when thermal expansion and contraction occur in the application environment, so that the sealing ring of the pressure transmitter and the shell and the plastic socket are still in an elastic sealing state, which prevents water vapor from entering the receiving cavity from between the shell and the plastic socket, improves the sealing property and reliability of the pressure transmitter, and enables it to be applied to special application conditions such as large temperature and humidity cycle changes or damp heat.

Description

Technical Field

[0001] The present invention relates to the field of sensors, and in particular to a pressure transmitter. Background Art

[0002] A pressure transmitter is a device or apparatus that can sense pressure signals and convert them into usable output electrical signals according to certain rules.

[0003] Pressure transmitters are the most commonly used sensors in industrial practice. They are widely used in various industrial automatic control environments, involving many industries such as water conservancy and hydropower, railway transportation, intelligent buildings, production automatic control, aerospace, military industry, petrochemicals, oil wells, electric power, ships, machine tools, pipelines, etc.

[0004] A pressure transmitter includes a mounting base, a housing, a socket, and a circuit structure. The mounting base, housing, and socket are connected in sequence to form the housing of the pressure transmitter to protect the circuit structure installed inside the housing. The housing is usually made of metal, and the socket is usually made of industrial plastic. The two materials have different thermal expansion and contraction rates, and industrial plastic has poor elasticity. Therefore, in environments with large temperature and humidity fluctuations, such as when used in excavators, the working conditions of excavators are relatively harsh, with high vibration, high humidity, exposed sensors, etc., and the temperature of the excavator increases with long working hours. During use, a gap is easily formed between the housing and the socket of an ordinary pressure transmitter due to the different thermal expansion and contraction rates, resulting in the failure of the sealing of the ordinary pressure transmitter. In turn, water vapor can enter the circuit structure inside the housing of the pressure transmitter through this gap and damage the circuit structure. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that the existing pressure transmitter is not suitable for harsh working conditions, hot and humid environments or environments with large temperature and humidity changes.

[0006] In order to solve the above technical problems, the present invention provides a pressure transmitter, including a shell, a plastic socket, a sealing ring and a pressing piece, wherein a receiving cavity is formed inside the shell; the plastic socket is connected to one end of the shell, and a sealing groove is provided at the connection transition position between the plastic socket and the inner wall surface of the shell, and the opening of the sealing groove is connected to the receiving cavity; the sealing ring is embedded in the sealing groove; the pressing piece is arranged in the receiving cavity, and the pressing piece is connected and fixed to the plastic socket through a hot air riveting process, and abuts against the sealing ring, so that the pressing piece presses the sealing ring, and the compression amount of the sealing ring is greater than the thermal expansion and contraction amount of the sealing ring.

[0007] In one embodiment of the present application, the sealing ring is made of one of silicone, hydrogenated nitrile butadiene rubber and / or the compression amount of the sealing ring is greater than 10%.

[0008] In one embodiment of the present application, a bevel is provided on the circumferential outer surface of the plastic socket, the sealing groove is formed between the bevel and the inner wall surface of the shell, and the sealing ring is elastically sealed with the bevel and the inner wall surface of the shell; or the cross-section of the sealing groove is triangular, trapezoidal or rectangular, and the sealing ring is elastically sealed with the inner wall surface of the sealing groove.

[0009] In one embodiment of the present application, a bending portion is provided on the shell, and the bending portion is injection-molded in the plastic socket; a plurality of bends are formed on the bending portion; and an angle of the bends is greater than 45°.

[0010] In one embodiment of the present application, a first positioning hole is provided on the pressing piece; the plastic socket is provided with a first positioning column, the first positioning column passes through the first positioning hole and extends into the receiving cavity, and the pressing piece is riveted to the plastic socket by hot air cold riveting on the side of the pressing piece away from the plastic socket.

[0011] In one embodiment of the present application, there are a plurality of first positioning posts, and the plurality of first positioning posts are symmetrically distributed on a side surface of the plastic socket facing the pressing piece.

[0012] In one embodiment of the present application, the pressure transmitter also includes a mounting base, a pressure seat and a circuit board; the mounting base is seal-welded to the end of the shell facing away from the plastic socket, so that the receiving cavity forms a closed cavity; the mounting base is provided with a mounting port, which connects the receiving cavity and the outer surface of the mounting base; one end of the pressure seat is seal-welded in the mounting port, and the other end extends into the receiving cavity; the pressure seat is provided with a blind hole, the opening of the blind hole is connected to the end face of the pressure seat facing away from the plastic socket, and the fluid to be measured can enter the blind hole to detect the pressure of the fluid; the circuit board is installed in the receiving cavity and is connected to the pressure seat and the plastic socket.

[0013] In one embodiment of the present application, a damping member is fixed at the opening of the blind hole, and a through hole is provided on the damping member, which connects the interior of the blind hole and the outer surface of the pressure seat, and the diameter of the through hole is smaller than the diameter of the blind hole; and / or the circumferential outer surface of the pressure seat at one end of the receiving cavity may be free of or may have one or more stress isolation grooves.

[0014] In one embodiment of the present application, a strain gauge is fixed to one end of the pressure seat close to the plastic socket, and a socket pin is provided on the plastic socket; the pressure transmitter also includes a bracket and a shielding cover, the bracket is fixed on the mounting base and is located on a side of the accommodating cavity close to the pressure seat, and the shielding cover is arranged in the accommodating cavity and on a side close to the plastic socket; the circuit board includes a first circuit board, a second circuit board and an electrical connector, the first circuit board is fixed on a side of the bracket facing the shielding cover and is electrically connected to the strain gauge, the second circuit board is fixed on a side of the shielding cover facing the bracket and is electrically connected to the socket pin, and the electrical connector connects the first circuit board and the second circuit board.

[0015] In one embodiment of the present application, the shielding cover is provided with an avoidance hole, which is used to avoid the first positioning column; and / or the circumferential outer surface of the shielding cover is provided with an elastic contact pin, which abuts the outer shell; and / or the first circuit board is provided with a third positioning hole, the second circuit board is provided with a fifth positioning hole, and the plastic socket is also provided with a second positioning column, the second positioning column extends toward one side of the bracket, and the second positioning column passes through the third positioning hole and the fifth positioning hole to position the first circuit board and the second circuit board; and / or the electrical connector is an elastic conductive component, and the two ends of the elastic conductive component are electrically connected to the first circuit board and the second circuit board respectively.

[0016] The present invention has the following beneficial effects: the housing of the pressure transmitter is connected to the plastic socket, a receiving cavity is formed inside the housing, a sealing groove is provided at the connection transition position between the plastic socket and the wall surface inside the housing, the opening of the sealing groove is connected to the receiving cavity, a sealing ring is embedded in the sealing groove, a pressing piece is provided in the receiving cavity, the pressing piece is tightly connected to the plastic socket by a hot air cold riveting process, thereby improving the connection strength between the pressing piece and the plastic socket, and making the pressing piece abut against the sealing ring and pressing the sealing ring tightly in the sealing groove, so that when the pressure transmitter is used in a vibration condition, the pressing piece can still maintain a state of pressing the sealing ring. Moreover, the compression amount of the sealing ring is greater than the volume deformation amount of the sealing ring itself and its surrounding components due to thermal expansion and contraction in the application environment, thereby ensuring that the sealing ring of the pressure transmitter, the housing and the plastic socket are still in an elastic sealing state, thereby preventing water vapor from entering the receiving cavity from between the housing and the plastic socket, improving the sealing and reliability of the pressure transmitter, and enabling it to be used in special application conditions such as large temperature and humidity cycle changes or humid heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of a pressure transmitter in one embodiment.

[0018] Figure 2yes Figure 1 The exploded structural diagram of the pressure transmitter is shown.

[0019] Figure 3 yes Figure 2 The pressure transmitter shown is a schematic diagram of the exploded structure from another perspective.

[0020] Figure 4 It is a schematic cross-sectional structural diagram of a pressure transmitter in a three-dimensional state in one embodiment.

[0021] Figure 5 It is a schematic diagram of the cross-sectional front view structure of a pressure transmitter in one embodiment.

[0022] Figure 6 and Figure 5 The cross-sectional structural diagram of the pressure transmitter shown in the AA direction.

[0023] Figure 7 This is a schematic diagram of the connection structure between the housing, plastic socket, sealing ring and pressing piece, in which the housing is cut away.

[0024] Figure 8 It is a schematic structural diagram of a bracket in one embodiment.

[0025] Figure 9 It is a schematic structural diagram of a shielding cover in one embodiment.

[0026] Figure 10 It is a schematic structural diagram of a first circuit board in one embodiment.

[0027] Figure 11 2 is a schematic structural diagram of a second circuit board in one embodiment.

[0028] Figure 12 It is a schematic cross-sectional structural diagram of a rear-end component in one embodiment.

[0029] Figure 13 yes Figure 12 The main structural diagram of the back-end components is shown.

[0030] Figure 14 It is a schematic cross-sectional structural diagram of a front-end component in one embodiment.

[0031] Figure 15 yes Figure 14 The main structural diagram of the front-end components is shown.

[0032] Figure 16 It is a schematic structural diagram of an electrical connector in one embodiment.

[0033] The reference numerals are as follows: 10-rear end assembly; 1-housing; 11-accommodating cavity; 12-bending portion; 2-plastic socket; 21-first positioning column; 22-sealing groove; 23-socket pin; 24-second positioning column; 25-third positioning column; 3-sealing ring; 4-pressing sheet; 41-first positioning hole; 5-shielding cover; 51-elastic contact pin; 52-second protrusion; 53-avoidance groove; 20-front end assembly; 6-mounting base; 61-base; 6 11-mounting port; 62-mounting hexagon; 7-pressure seat; 71-blind hole; 72-stress isolation groove; 73-strain gauge; 74-damping element; 741-through hole; 8-bracket; 81-first protrusion; 9-circuit board; 91-first circuit board; 911-second positioning hole; 912-third positioning hole; 92-second circuit board; 921-fourth positioning hole; 922-fifth positioning hole; 93-electrical connector; 931-shrapnel; 932-protective shell. DETAILED DESCRIPTION

[0034] Typical embodiments embodying the features and advantages of the present invention are described in detail in the following description. It should be understood that the present invention is capable of various variations in different embodiments without departing from the scope of the present invention, and that the descriptions and illustrations herein are intended to be illustrative rather than limiting.

[0035] In the description of this application, it should be understood that in the embodiments shown in the drawings, indications of directions or positional relationships (such as up, down, left, right, front, and back) are merely for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the positions of these elements are "first" or "second," they are only used for descriptive purposes and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "multiple" means two or more, unless otherwise explicitly and specifically defined.

[0036] This application provides a pressure transmitter primarily for use in tunnel excavation equipment, such as excavators. Excavators operate in harsh conditions, characterized by high vibration, high humidity, and exposed sensors. Furthermore, excavators experience elevated temperatures over time, making conventional products susceptible to failure during use. The structural design of the pressure transmitter in this application is specifically tailored to the harsh operating conditions of excavators, providing excellent protection. Furthermore, assembly is simple, reliable, and space-saving.

[0037] The pressure transmitter of the present application is provided with a sealing groove at the connection transition between the plastic socket and the inner wall of the housing. The opening of the sealing groove communicates with the receiving cavity within the housing. A sealing ring is disposed within the housing and is compressed within the sealing groove by a pressing plate, so that the sealing ring is in contact with both the inner wall of the housing and the surface of the plastic socket. The compression of the sealing ring is greater than the thermal expansion and contraction of the sealing ring in the application environment. As a result, the sealing ring, the housing, and the plastic socket maintain an elastic seal. This prevents moisture from entering the receiving cavity between the housing and the plastic socket, improving the sealing performance of the pressure transmitter and enabling its application in special environments such as high or low temperatures. Furthermore, the pressing plate and the plastic socket are tightly connected through a hot air cold riveting process, which improves the connection strength between the pressing plate and the plastic socket, allowing the pressing plate to remain in a state of compression against the sealing ring when the pressure transmitter is used in vibrating conditions. The terms "high temperature" and "low temperature" are relative to room temperature and do not limit specific temperatures. Generally, low temperature refers to -40°C to 25°C, and high temperature refers to 40°C to 150°C.

[0038] For details, see Figures 1 to 7 The pressure transmitter includes a housing 1, a plastic socket 2, a mounting base 6, a pressure seat 7, a circuit board 9, a sealing ring 3 and a pressing piece 4. The plastic socket 2 and the mounting base 6 are respectively fixed at the axial ends of the housing 1, and the housing 1, the plastic socket 2 and the mounting base 6 together form a sealed receiving cavity 11. The circuit board 9 is installed in the receiving cavity 11, so that the housing 1, the plastic socket 2 and the mounting base 6 play a protective role for the circuit board 9. The pressure seat 7 is fixed on the mounting base 6 and contacts the fluid to be measured to detect the pressure of the fluid to be measured. The pressure seat 7 is connected to the circuit board 9 so that the pressure is converted into an electrical signal and output to the controller of the device using the pressure transmitter. The fluid to be measured can be a gas, a liquid or a gas-liquid mixture.

[0039] The sealing ring 3 and the pressing piece 4 are arranged in the accommodating cavity 11. The sealing ring 3 abuts against the plastic socket 2 and the shell 1. The pressing piece 4 is connected to the plastic socket 2 and abuts against the sealing ring 3, so that the sealing ring 3 maintains an elastic sealing state with the shell 1 and the plastic socket 2, thereby improving the sealing between the plastic socket 2 and the shell 1.

[0040] Specifically, the housing 1 is annular, so that a receiving cavity 11 is formed inside the housing 1. A bending portion 12 is provided at one axial end of the housing 1, and the bending portion 12 is injection-molded together with the plastic socket 2. Figure 5 In the illustrated embodiment, the bent portion 12 has two bends, each forming a 90-degree angle. In other embodiments, the bent portion 12 may have one, three, or more bends, and the bend angles may be other angles. Preferably, the angles at the bends are greater than 45°, thereby further stabilizing the connection between the housing 1 and the plastic socket 2.

[0041] The plastic socket 2 can be in the form of a straight-out cable (i.e., PG7 locking wire), a rimmed socket, a Hussmann connector, or a housing / hexagonal insert. The plastic socket 2 includes socket pins 23, which are conductive components, and a plastic body. The plastic body is formed by injection molding industrial plastic, and the socket pins 23 and the plastic body are integrally molded, ensuring a complete elastic seal between the socket pins 23 and the plastic body. The socket pins 23 penetrate the plastic body, with one end extending into the receiving cavity 11 for connection to the circuit board 9. The other end is located outside the plastic body and is connected via wires to the controller of the device using the pressure transmitter.

[0042] The plastic body is also integrally injection-molded with the housing 1, completely covering the bent portion 12 of the housing 1. This ensures that even when the pressure transmitter is subjected to axial tension, the plastic socket 2 and the housing 1 will not separate, thereby enhancing the secure connection between the two. Furthermore, while ensuring the secure connection between the plastic socket 2 and the housing 1, the length of the portion of the plastic socket 2 covering the housing 1 can be shortened, thereby reducing the axial length of the pressure transmitter and achieving miniaturization. When the materials of the plastic socket 2 and the housing 1 expand and contract due to heat, a gap channel forms, which becomes curved, increasing the resistance and length of the gap channel for water vapor to pass through, and also improving the seal between the plastic socket 2 and the housing 1.

[0043] To form the plastic socket 2, the socket pins 23 and the housing 1 are first fixed to corresponding positions in the mold, with a distance between the outer wall of the housing 1 and the inner wall of the mold cavity. A high-temperature industrial plastic solution is then injected into the mold, covering the bent portion 12 of the housing 1. After the solution cools and solidifies, the industrial plastic forms a plastic body that is fixed to the socket pins 23 and the housing 1. This arrangement wraps the plastic body around both the inner and outer sides of the housing 1, increasing the contact area between the housing 1 and the plastic socket 2 and enhancing the secure connection between the two.

[0044] In one embodiment, a sealing groove 22 (corresponding to Figure 5 The sealing ring 3 is located in the sealing groove 22, which is also the connection transition position between the plastic socket 2 and the inner wall surface of the shell 1). The opening of the sealing groove 22 is communicated with the accommodating cavity 11. The sealing ring 3 is installed in the sealing groove 22, and the pressing piece 4 is arranged at the opening of the sealing groove 22, so that the pressing piece 4 presses the sealing ring 3 tightly in the sealing groove 22, and the sealing ring 3 is elastically sealed with the plastic socket 2 and the shell 1 at the same time, thereby improving the sealing between the plastic socket 2 and the shell 1.

[0045] In this embodiment, since the plastic socket 2 and the housing 1 are integrally injection-molded, it is not possible to install the plastic socket 2 by first sleeve-fitting the sealing ring 3 onto the outer surface of the plastic socket 2 and then inserting the plastic socket 2 with the sealing ring 3 into the interior of the housing 1. Therefore, the present application arranges the opening of the sealing groove 22 to communicate with the receiving cavity 11, so that the sealing ring 3 can be installed into the sealing groove 22 from one side of the receiving cavity 11. The pressing piece 4 is arranged at the opening of the sealing groove 22, so that the pressing piece 4 presses the sealing ring 3 tightly into the sealing groove 22, thereby enhancing the sealing between the housing 1 and the plastic socket 2. Furthermore, the sealing ring 3 and the pressing piece 4 are easy to install, and the process is simple.

[0046] Compared with the external gluing method of applying a layer of soft glue at the connection position between the shell 1 and the outside of the socket for sealing, the glue in the external gluing method is located on the outside and is easily affected by touch or aging and becomes ineffective, and can only be used in some occasions with better working conditions. The sealing ring 3 of the present application is arranged inside the accommodating cavity 11, and the sealing performance is not easy to fail, and can adapt to different application environments.

[0047] Compared to internal gluing, which involves applying a layer of soft glue to seal the connection between the housing 1 and the interior of the socket, the sealing performance of this method depends on the cleanliness of the gluing location, such as the presence of dust and oil film, the uniformity of the glue application, and the consistency of the gluing process. Therefore, internal gluing requires a good process guarantee to improve the level of protective performance. The sealing ring 3 of this application has the ability to elastically deform. Under the pressure of the pressing plate 4, it can achieve a complete elastic seal between the housing 1 and the plastic socket 2, with good sealing performance and simple process.

[0048] exist Figure 5 In the illustrated embodiment, the plastic socket 2 has an inclined surface at one end within the housing 1, forming a sealing groove 22 between the inclined surface and the inner wall of the housing 1. The cross-section of the sealing groove 22 is triangular or trapezoidal, meaning that the bottom of the sealing groove 22 is smaller than the opening. When the pressing piece 4 presses the sealing ring 3 into the sealing groove 22, the sealing ring 3 slides along the inclined surface into the sealing groove 22. This further strengthens the elastic seal between the sealing ring 3, the inclined surface, and the inner wall of the housing 1, thereby improving the sealing between the plastic socket 2 and the housing 1. In other embodiments, the cross-section of the sealing groove 22 may also be rectangular or have other shapes.

[0049] The overall volume of the pressure transmitter is relatively small. In this embodiment, the sealing groove 22 is sized to be a right-angled triangle with a length of 3 mm and a width of 2.3 mm. The diameter of the sealing ring 3 is greater than or equal to 1.5 mm. This ensures sufficient contact sealing surface while minimizing space requirements. In other embodiments, the sealing groove 22 and sealing ring 3 may have other dimensions.

[0050] The plastic socket 2 is also provided with a first positioning post 21, which extends into the receiving cavity 11. The first positioning post 21 passes through the pressing piece 4 and secures the pressing piece 4 on the side of the pressing piece 4 facing away from the plastic socket 2. In one embodiment, the first positioning post 21 is a hot air rivet post. The free end of the hot air rivet post passes through the pressing piece 4 and forms a protrusion on the side of the pressing piece 4 facing away from the plastic socket 2 through hot air rivet processing. This protrusion can prevent the pressing piece 4 from separating from the plastic socket 2, allowing the pressing piece 4 to be riveted to the plastic socket 2 and thus securing the pressing piece 4. After the hot air rivet processing, the connection between the pressing piece 4 and the plastic socket 2 has high strength, low stress, and reliable fixing effect. Therefore, even when the pressure transmitter is used in vibrating working conditions, the sealing effect of the sealing ring 3 will not fail due to separation of the pressing piece 4 from the plastic socket 2. Moreover, since the pressing piece 4 is riveted to the plastic socket 2 through the hot air rivet process, compared with the screw fixing method, the size of the pressure transmitter can be reduced in the axial direction.

[0051] The steps for riveting the pressing piece 4 to the plastic socket 2 by the hot air cold riveting process are as follows: first, the first positioning post 21 is passed through the pressing piece 4, and then the hot air cold riveting post is melted by hot air to soften the end of the hot air cold riveting post, and then the hot air cold riveting post is pressed down by the cold riveting mold column to form the hot air cold riveting post, so as to achieve riveting and fixing between the hot air cold riveting post and the pressing piece 4. Therefore, by connecting the first positioning post 21 and the pressing piece 4 by hot air cold riveting, automatic positioning can be achieved without manual alignment and welding, which can not only realize automated production, but also improve product quality, greatly reduce labor costs, and greatly improve processing efficiency.

[0052] There are multiple hot air cooling rivet studs, which are distributed on the side of the plastic socket 2 facing the pressing piece 4. Figure 7 In the illustrated embodiment, four hot air cooling rivet studs are provided. These four hot air cooling rivet studs are positioned off-center on the plastic socket 2, and two hot air cooling rivet studs are symmetrically arranged. When the hot air cooling rivet studs pass through the pressing piece 4, the pressing piece 4 and the plastic socket 2 are aligned. In other embodiments, one, two, three, or more hot air cooling rivet studs may be provided.

[0053] The diameter and protrusion height of the hot air cooling rivet column are designed according to the required strength. The strength refers to the rebound force during the O-ring press-fitting process, high and low temperature deformation force, etc. Figure 7 In the embodiment shown, after the pressing sheet is pressed, the height of the protrusion is 3.4 mm, and the rivet column is circular with a diameter of 1.6 mm.

[0054] The plastic socket 2 is further provided with a second positioning post 24 . The second positioning post 24 extends toward one side of the mounting base 6 . The second positioning post 24 passes through the circuit board 9 to achieve positioning of the circuit board 9 .

[0055] In one embodiment, the cross-section of the second positioning post 24 is non-circular, so that the second positioning post 24 not only positions the circuit board 9 but also prevents the circuit board 9 from rotating about the second positioning post 24. In other embodiments, the cross-section of the second positioning post 24 is circular, and multiple second positioning posts 24 are provided at intervals, which can also position the circuit board 9 and prevent the circuit board 9 from rotating about the second positioning post 24.

[0056] The plastic socket 2 is further provided with a third positioning post 25, which extends into the receiving cavity 11 and is shorter than the second positioning post 24. The third positioning post 25 abuts against the side of the circuit board 9 facing away from the pressure seat 7 to limit the axial position of the circuit board 9.

[0057] In one embodiment, the third positioning post 25 can be integrally formed with the second positioning post 24, and the cross-sectional dimensions of the third positioning post 25 are larger than the cross-sectional dimensions of the second positioning post 24, so that the third positioning post 25 forms an end surface for limiting the position of the circuit board 9. The third positioning post 25 can also be spaced apart from the second positioning post 24.

[0058] exist Figure 7 In the embodiment shown, there is one second positioning column 24 and two third positioning columns 25. The two third positioning columns 25 are symmetrically arranged, and one of the third positioning columns 25 is integrated with the second positioning column 24, so that the third positioning column 25 can stably support the circuit board 9, and also make the overall structure of the pressure transmitter more compact, realizing a miniaturized setting.

[0059] In one embodiment, the sealing ring 3 is an O-ring or a rubber gasket. Preferably, the sealing ring 3 is made of silicone or hydrogenated nitrile butadiene rubber with a low permanent deformation rate. The sealing ring 3 has excellent elastic deformation ability, so that under special conditions of low or high temperature, it can still maintain elastic sealing with the shell 1 and the plastic socket 2, thereby improving the sealing between the plastic socket 2 and the shell 1.

[0060] Among them, the compressibility of the sealing ring 3 is greater than the thermal expansion and contraction rate of the sealing ring 3, and after the sealing ring 3 is installed in the sealing groove 22, the pressing sheet 4 compresses the sealing ring 3 to a contraction amount that is greater than the thermal expansion and contraction amount of the sealing ring 3 at the application environment temperature, so that the sealing ring 3 still maintains a sealed state at the temperature of the working environment.

[0061] For example, a pressure transmitter is used in tunnel excavation equipment, which typically operates in an environment of around 20°C and with a humidity of over 80%. As the tunnel excavation equipment operates, heat is generated, causing the temperature of the pressure transmitter to rise. However, the operating temperature of a pressure transmitter typically does not exceed 90°C. When the pressing disc 4 compresses the sealing ring, the sealing ring is compressed by 20%. When the sealing ring 3 expands and contracts by 2% at the application temperature, the sealing ring 3 still has an 18% compression, maintaining an elastic seal between the sealing ring 3, the housing 1, and the plastic socket 2. This prevents moisture from entering the receiving cavity 11 from between the housing 1 and the plastic socket 2.

[0062] In a preferred embodiment, the compressibility of the sealing ring 3 is greater than 10%, and the thermal expansion and contraction of the sealing ring 3 under the temperature of the application environment is less than 5%. The thermal expansion and contraction of the sealing ring 3 under the application environment can be calculated based on the material and the application environment temperature, and the compression of the sealing ring 3 can be calculated based on the volume change of the sealing ring 3 when the pressing plate 4 presses the sealing ring 3.

[0063] The pressing sheet 4 is preferably made of metal, which can be stainless steel or carbon steel, with a thickness greater than or equal to 0.8 mm. The material and thickness of the pressing sheet 4 mainly consider the hardness and material of the sealing ring 3, ensure the rigidity of the pressing sheet 4, maintain the long-term reliability of the pressed sealing ring 3, and prevent deformation during high and low temperature thermal expansion and contraction processes or after aging.

[0064] The pressing piece 4 is provided with a first positioning hole 41 . The position of the first positioning hole 41 corresponds to the position of the first positioning post 21 . The first positioning post 21 passes through the first positioning hole 41 to achieve positioning between the pressing piece 4 and the plastic socket 2 .

[0065] See again Figures 2 to 6 The mounting base 6 includes a base 61 and a mounting hexagon 62. The mounting hexagon 62 is welded to the shell 1. The base 61 is arranged at one end of the mounting hexagon 62 away from the shell 1. The mounting hexagon 62 is welded to the base 61 or integrally formed to achieve a sealed connection between the mounting base 6 and the shell 1, so that the accommodating cavity 11 forms a closed cavity.

[0066] The base 61 is provided with external threads for threaded connection to the equipment to which the pressure transmitter is applied. The outer circumferential surface of the mounting hexagon 62 is provided with a wrench slot for receiving a wrench. When installing the pressure transmitter on the equipment, the wrench is engaged in the wrench slot and then the pressure transmitter is tightened to the equipment, making it easy to install the pressure transmitter on the equipment.

[0067] The outer diameter of the mounting hexagon 62 is larger than the outer diameter of the base 61, so that the mounting hexagon 62 serves to limit the depth of the threaded hole of the pressure transmitter into the device. A sealing ring can also be provided on the outer surface of the base 61 to achieve a sealed connection between the pressure transmitter and the device.

[0068] An installation port 611 is provided on the base 61, which extends along the axial direction of the base 61 and is connected to the end faces of the base 61 at both ends, that is, the installation port 611 is connected to the outside of the accommodating cavity 11 and the base 61, and the pressure seat 7 is sealed and welded in the installation port 611, so that the fluid cannot enter the accommodating cavity 11 from between the pressure seat 7 and the base 61.

[0069] The pressure seat 7 is provided with a blind hole 71, the opening of which communicates with the end face of the pressure seat 7 facing away from the plastic socket 2. The fluid to be measured can enter the blind hole 71 to detect the fluid pressure. A strain gauge 73 is fixed to the end face of the pressure seat 7 near the plastic socket 2. The strain gauge 73 is connected to the circuit board 9. When fluid enters the blind hole 71 of the pressure seat 7, the fluid pressure causes the pressure seat 7 to elastically deform. The amount of elastic deformation is detected by the strain gauge 73 and then converted into an electrical signal by the circuit board 9, which then outputs the pressure signal.

[0070] Among them, the depth of the blind hole 71 extends into the accommodating cavity 11, and the thickness between the bottom of the blind hole 71 and the end face of the pressure seat 7 close to the plastic socket 2 is smaller than that at other positions. Therefore, the elastic deformation of the pressure seat 7 at the bottom of the blind hole 71 is larger, making the elastic deformation of the pressure seat 7 easier to be detected by the strain gauge 73.

[0071] The pressure seat 7 is a stress-sensitive structure. When the pressure seat 7 is connected to the base 61 or the pressure transmitter is connected to the device, stress will be present on the pressure seat 7. The stress will affect the accuracy of the pressure transmitter in detecting fluid pressure, that is, the sensitivity of the pressure transmitter. The present application provides one or more stress isolation grooves 72 on the pressure seat 7. The stress isolation grooves 72 are annular and are arranged on the circumferential outer surface at one end of the receiving cavity 11. When stress is generated on the pressure seat 7, the stress isolation grooves 72 can block the transmission of stress, so that the stress cannot be transmitted to the strain gauge 73, thereby avoiding affecting the accuracy and long-term stability of the strain gauge 73. In other embodiments, the stress isolation grooves 72 may not be provided on the pressure seat 7.

[0072] A damping member 74 is fixed at the opening of the blind hole 71. The damping member 74 is provided with a through hole 741 connecting the interior of the blind hole 71 and the outer surface of the pressure seat 7. The diameter of the through hole 741 is smaller than the diameter of the blind hole 71, so that when the fluid to be measured changes suddenly, the fluid pressure inside the pressure seat 7 will not change suddenly, that is, the water hammer effect is avoided, and the measured fluid is prevented from impacting the bottom of the pressure seat 7, resulting in over-range and damage to the product.

[0073] The pressure transmitter also includes a bracket 8 and a shielding cover 5. The bracket 8 is fixed on the base 61 and is located on the side of the receiving cavity 11 close to the pressure seat 7. The shielding cover 5 is arranged in the receiving cavity 11 and close to the side of the plastic socket 2. The circuit board 9 is arranged between the bracket 8 and the shielding cover 5. The bracket 8, the shielding cover 5 and the shell 1 are all made of metal to shield the circuit board 9.

[0074] In one embodiment, the circuit board 9 includes a first circuit board 91 and a second circuit board 92 . The first circuit board 91 is connected to the strain gauge 73 , and the second circuit board 92 is connected to the socket pins 23 .

[0075] See Figure 6 and Figure 8 The bracket 8 is annular, that is, the end of the bracket 8 close to the plastic socket 2 is connected to the pressure seat 7, so as not to affect the electrical connection between the strain gauge 73 and the first circuit board 91. The first circuit board 91 and the bracket 8 can be fixedly connected by bonding, screw connection or clamping.

[0076] exist Figure 8 In the illustrated embodiment, a first protrusion 81 is provided on the bracket 8, and the first protrusion 81 extends toward one side of the plastic socket 2. When the first circuit board 91 is fixed to the bracket 8, the first circuit board 91 is sleeved on the first protrusion 81, thereby realizing the mutual positioning between the first circuit board 91 and the bracket 8.

[0077] See Figure 6 and Figure 9 The shielding cover 5 is annular, and an elastic contact pin 51 is provided on the circumferential outer surface of the shielding cover 5. When the shielding cover 5 is placed in the receiving cavity 11, the elastic contact pin 51 abuts against the inner wall of the shell 1 under the elastic action of the elastic contact pin 51, so that the shielding cover 5 is fixed inside the receiving cavity 11. In addition, the elastic contact pin 51 can realize the conductive connection between the shielding cover 5 and the shell 1, and realize the ground connection of the circuit board.

[0078] exist Figure 9 In the embodiment shown, a second protrusion 52 is provided on the shielding cover 5, and the second protrusion 52 extends toward one side of the pressure seat 7. When the second circuit board 92 is installed on the shielding cover 5, the second circuit board 92 is sleeved on the second protrusion 52, so that the second protrusion 52 plays a positioning role for the second circuit board 92.

[0079] An avoidance groove 53 is provided on the shielding cover 5, and the position of the avoidance groove 53 corresponds to the position of the first positioning column 21, so that the protrusion formed by the hot air cold riveting process of the first positioning column 21 can extend into the avoidance groove 53, thereby reducing the axial size of the pressure transmitter.

[0080] The first circuit board 91 and the second circuit board 92 are spaced apart in the axial direction of the housing 1 , thereby reducing the area of ​​each circuit board 9 and further reducing the radial size of the pressure transmitter.

[0081] See Figure 10 The first circuit board 91 is provided with a second positioning hole 911 that mates with the first protrusion 81, and a third positioning hole 912 that mates with the second positioning post 24. When the first circuit board 91 is connected to the bracket 8, the first protrusion 81 is inserted into the second positioning hole 911, thereby positioning the first circuit board 91 with the bracket 8. When the first circuit board 91 and the bracket 8 are formed into a single unit and connected to the plastic socket 2, the second positioning post 24 passes through the third positioning hole 912, thereby positioning the first circuit board 91 and the bracket 8 with the plastic socket 2.

[0082] See Figure 11 The second circuit board 92 is provided with a fourth positioning hole 921 that mates with the second protrusion 52, and a fifth positioning hole 922 that mates with the second positioning post 24. When the second circuit board 92 is connected to the shielding cover 5, the second protrusion 52 is inserted into the fourth positioning hole 921, thereby positioning the second circuit board 92 with the shielding cover 5. When the second circuit board 92 and the shielding cover 5 are formed into a single unit and connected to the plastic socket 2, the second positioning post 24 passes through the fifth positioning hole 922, thereby positioning the second circuit board 92 and the shielding cover 5 with the plastic socket 2.

[0083] See Figures 12 to 15 When assembling the pressure transmitter, the pressure transmitter is divided into two parts, a front-end component 20 and a rear-end component 10, at the connection between the housing 1 and the mounting hexagon 62. The front-end component 20 and the rear-end component 10 are assembled separately, and then the front-end component 20 and the rear-end component 10 are fixed together, so that most of the parts of the pressure transmitter are assembled outside the receiving cavity 11, thereby making assembly more convenient.

[0084] See Figure 12 and Figure 13 The back-end assembly 10 includes a plastic socket 2, a housing 1, a sealing ring 3, a pressing piece 4, a shielding cover 5, a second circuit board 92 and an electrical connector 93. When assembling the back-end assembly 10, the assembly can be performed in the following order:

[0085] The plastic socket 2 is injection molded together with the housing 1 so that the plastic socket 2 and the housing 1 are fixed together.

[0086] Install the sealing ring 3 in the sealing groove 22.

[0087] The pressing piece 4 is fixed in the receiving cavity 11. When the pressing piece 4 is placed in the receiving cavity 11, the first positioning post 21 is passed through the first positioning hole 41 on the pressing piece 4, and then pressure is applied to the pressing piece 4 so that the pressing piece 4 presses the sealing ring 3. Then, the hot air cooling riveting process is performed on the side of the first positioning post 21 on the pressing piece 4 away from the sealing ring 3 to achieve a riveted connection between the pressing piece 4 and the plastic socket 2.

[0088] The second circuit board 92 is fixed to the shielding cover 5, and the electrical connector 93 is welded to the second circuit board 92. When the second circuit board 92 is mounted on the shielding cover 5, the fourth positioning hole 921 on the second circuit board 92 cooperates with the second protrusion 52 on the bracket 8 to achieve alignment and positioning, thereby defining the circumferential angle of the second circuit board 92. The second protrusion 52 is welded to the second circuit board 92, thereby fixing the second circuit board 92, the shielding cover 5, and the electrical connector 93 together.

[0089] The entire assembly after the second circuit board 92, the shielding cover 5, and the electrical connector 93 are fixed together is installed in the receiving cavity 11. When the entire assembly is placed in the receiving cavity 11, the fifth positioning holes 922 on the second circuit board 92 engage with the second positioning posts 24. The entire assembly is then pressed into the receiving cavity 11 until the second circuit board 92 abuts against the third positioning posts 25. The assembly is then fixed to the housing 1 under the elastic force of the elastic contact pins 51 of the shielding cover 5, preventing the entire assembly after the second circuit board 92, the shielding cover 5, and the electrical connector 93 are fixed together from moving at will.

[0090] See Figure 14 and Figure 15 The front-end assembly 20 includes a base 61, a mounting hexagon 62, a bracket 8, a pressure seat 7, a damping member 74, and a first circuit board 91. When assembling the front-end assembly 20, the assembly can be performed in the following order:

[0091] The base 61 and the mounting hexagon 62 are integrally formed or welded together to form the mounting base 6 .

[0092] Fix the bracket 8 on the mounting base 6. Figure 15 In the embodiment, the bracket 8 is fixed to the base 61, and the fixed connection between the bracket 8 and the base 61 can be welding, bonding, screw connection or clamping. Preferably, the bracket 8 and the base 61 are welded, so that no other connecting structure is required between the bracket 8 and the base 61, thereby making the connection structure simpler.

[0093] Insert the pressure seat 7 into the mounting hole on the base 61, and then weld the pressure seat 7 and base 61 to secure the pressure seat 7 to the base 61. The connection between the pressure seat 7 and base 61 is placed after the connection between the bracket 8 and base 61, so that welding between the bracket 8 and base 61 does not affect the pressure seat 7. In other embodiments, the two processes can be interchanged.

[0094] The strain gauge 73 is fixed to the pressure seat 7, and the first circuit board 91 is fixed to the bracket 8, and an electrical connection is established between the strain gauge 73 and the first circuit board 91. The fixed connection between the strain gauge 73 and the pressure seat 7 is achieved by bonding or binding with a strap. When the first circuit board 91 is fixed to the bracket 8, the second positioning hole 911 on the first circuit board 91 cooperates with the first protrusion 81 on the bracket 8 to achieve alignment and positioning, thereby defining the circumferential angle of the first circuit board 91.

[0095] The damping member 74 is fixed on the pressure seat 7. Wherein, the installation of the damping member 74 can be placed at the end, and also after the pressure seat 7 is produced, the damping member 74 can be fixed on the pressure seat 7.

[0096] See again Figure 5 , the front-end assembly 20 and the back-end assembly 10 are connected together, and welding is performed between the mounting hexagonal bracket 62 and the housing 1 to secure the front-end assembly 20 and the back-end assembly 10 together. When the front-end assembly 20 and the back-end assembly 10 are connected together, the third positioning hole 912 on the first circuit board 91 engages with the second positioning post 24, and then slides along the second positioning post 24, so that the end of the electrical connector 93 facing away from the second circuit board 92 is electrically connected to the first circuit board 91. Then, welding is performed between the mounting hexagonal bracket 62 and the housing 1, so that the receiving cavity 11 forms a sealed cavity.

[0097] In one embodiment, the electrical connector 93 is an elastic conductive member, and the elastic direction of the elastic conductive member is the same as the axial direction of the shell 1, so that when the front-end component 20 and the rear-end component 10 are docked, the accuracy of the electrical connection between the electrical connector 93 and the first circuit board 91 can be ensured, and the mounting hexagon 62 and the shell 1 can be aligned.

[0098] exist Figure 16 In the embodiment shown, the electrical connector 93 includes an S-shaped spring piece 931 and a protective shell 932. The protective shell 932 is arranged on the outside of the spring piece 931 to limit the deformation direction of the spring piece 931 and to limit the collision between the electrical components on the first circuit board 91 and the second circuit board 92.

[0099] In the pressure transmitter of the present application, the housing 1 and the plastic socket 2 are integrally injection-molded together, and the interior of the housing 1 forms a receiving chamber 11. A sealing groove 22 is provided at the connection transition position between the plastic socket 2 and the inner wall of the housing 1. The opening of the sealing groove 22 is connected to the receiving chamber 11. A sealing ring 3 is embedded in the sealing groove 22. A pressing piece 4 is provided in the receiving chamber 11. The pressing piece 4 is tightly connected to the plastic socket 2 by a hot air cold riveting process, so that it abuts against the sealing ring 3. The pressing piece 4 presses the sealing ring 3 in the sealing groove 22, so that when the pressure transmitter is used in a vibration condition, the pressing piece 4 can still maintain a state of pressing the sealing ring 3. Moreover, the compression amount of the sealing ring 3 is greater than the thermal expansion and contraction amount of the sealing ring 3 under the application environment. Therefore, when the plastic socket and housing of the pressure transmitter expand and contract, the sealing ring 3, the housing 1 and the plastic socket 2 remain in an elastic sealing state. Therefore, moisture is prevented from entering the receiving chamber from between the housing 1 and the plastic socket 2, thereby improving the sealing performance of the pressure transmitter and enabling it to be used in special environments such as high or low temperatures. This configuration enables the pressure transmitter of the present application to pass tests such as IP68 (2-meter water depth, 24 hours), IP69K, damp heat vibration test (30G, 95% humidity), GB / T 2423.17 salt spray test, GB / T 2423.3 steady state damp heat test, GB / T 2423.4 Db damp heat cycle test, and GB / T28046.4-2011 ice water test. Existing pressure transmitters, on the other hand, typically fail these special operating condition tests and are difficult to use or have a short service life in harsh operating conditions.

[0100] While the present invention has been described with reference to several exemplary embodiments, it should be understood that the terms used are intended to be illustrative and exemplary rather than restrictive. Since the present invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above-described embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope of the appended claims. All changes and modifications that fall within the scope of the claims or their equivalents are intended to be covered by the appended claims.

Claims

1. A pressure transmitter, characterized in that: include: A housing, the interior of which forms a receiving cavity; A plastic socket connected to one end of the shell, a sealing groove is provided at a connection transition position between the plastic socket and the inner wall surface of the shell, and an opening of the sealing groove is communicated with the receiving cavity; A sealing ring, embedded in the sealing groove; A pressing sheet is arranged in the receiving cavity, the pressing sheet is connected and fixed to the plastic socket by a hot air cold riveting process, and abuts against the sealing ring, so that the pressing sheet presses the sealing ring tightly, and the compression amount of the sealing ring is greater than the thermal expansion and contraction amount of the sealing ring; The compression amount of the sealing ring is greater than 10%; The circumferential outer surface of the plastic socket is provided with an inclined surface, the sealing groove is formed between the inclined surface and the inner wall surface of the shell, and the sealing ring is elastically sealed with the inclined surface and the inner wall surface of the shell.

2. The pressure transmitter according to claim 1, characterized in that: The sealing ring is made of one of silicone, hydrogenated nitrile butadiene and rubber.

3. The pressure transmitter according to claim 2, characterized in that: The cross section of the sealing groove is triangular, trapezoidal or rectangular.

4. The pressure transmitter according to claim 3, characterized in that: The shell is provided with a bending portion, and the bending portion is injection-molded in the plastic socket; A plurality of bends are formed on the bend portion; The bending angle is greater than 45°.

5. The pressure transmitter according to claim 1, characterized in that: The pressing sheet is provided with a first positioning hole; the plastic socket is provided with a first positioning column, the first positioning column passes through the first positioning hole and extends into the accommodating cavity, and the pressing sheet is riveted to the plastic socket by hot air cold riveting on the side of the pressing sheet away from the plastic socket.

6. The pressure transmitter according to claim 5, characterized in that: There are a plurality of first positioning posts, and the plurality of first positioning posts are distributed on the side surface of the plastic socket facing the pressing sheet.

7. The pressure transmitter according to claim 1, characterized in that: The pressure transmitter also includes a mounting base, a pressure seat and a circuit board; The mounting base is sealed and welded to the end of the housing away from the plastic socket, so that the receiving cavity forms a closed cavity; the mounting base is provided with a mounting opening, and the mounting opening communicates with the receiving cavity and the outer surface of the mounting base; One end of the pressure seat is sealed and welded in the installation port, and the other end extends into the receiving cavity; a blind hole is provided on the pressure seat, and the opening of the blind hole is connected to an end surface of the pressure seat away from the plastic socket, so that the fluid to be measured can enter the blind hole to detect the pressure of the fluid; The circuit board is installed in the receiving cavity and is connected to the pressure seat and the plastic socket.

8. The pressure transmitter according to claim 7, characterized in that: A damping member is fixed at the opening of the blind hole, and a through hole is provided on the damping member to communicate with the interior of the blind hole and the outer surface of the pressure seat, and the diameter of the through hole is smaller than the diameter of the blind hole; and / or One or more stress isolation grooves are provided on the circumferential outer surface of the pressure seat at one end of the accommodating cavity.

9. The pressure transmitter according to claim 7, characterized in that: A strain gauge is fixed to one end of the pressure seat close to the plastic socket, and a socket pin is provided on the plastic socket; The pressure transmitter further comprises a bracket and a shielding cover, wherein the bracket is fixed on the mounting base and is located in the receiving cavity on one side close to the pressure seat, and the shielding cover is arranged in the receiving cavity and on one side close to the plastic socket; The circuit board includes a first circuit board, a second circuit board and an electrical connector. The first circuit board is fixed to a side of the bracket facing the shielding cover and is electrically connected to the strain gauge. The second circuit board is fixed to a side of the shielding cover facing the bracket and is electrically connected to the socket pin. The electrical connector connects the first circuit board and the second circuit board.

10. The pressure transmitter according to claim 9, characterized in that: The shielding cover is provided with an avoidance hole, and the avoidance hole is used to avoid the first positioning column.

11. The pressure transmitter according to claim 9, characterized in that: The circumferential outer surface of the shielding cover is provided with elastic contact pins, and the elastic contact pins are in contact with the shell.

12. The pressure transmitter according to claim 9, characterized in that: A third positioning hole is provided on the first circuit board, a fifth positioning hole is provided on the second circuit board, and a second positioning column is also provided on the plastic socket. The second positioning column extends toward one side of the bracket, and the second positioning column passes through the third positioning hole and the fifth positioning hole to position the first circuit board and the second circuit board.

13. The pressure transmitter according to claim 9, characterized in that: The electrical connection member is an elastic conductive member, and two ends of the elastic conductive member are electrically connected to the first circuit board and the second circuit board respectively.

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