Miniature pressure sensor and preparation method thereof

Abstract

The invention relates to a miniature pressure sensor and a preparation method, the miniature pressure sensor comprises a shell, a mounting joint, a mounting structure, a circuit board and a pressure sensing element, the mounting joint is provided with a first end capable of being riveted with a hydraulic control valve body and is also provided with a second end capable of being connected with the pressure sensing element, and the shell is connected with the mounting joint; the pressure sensing element and the circuit board are electrically connected and arranged in the shell, the pressure sensing element is sleeved with the mounting structure, the circuit board is mounted on the mounting connector through the mounting structure, a liquid inlet is formed in the first end of the mounting connector, a drainage hole communicated with the liquid inlet is formed in the second end of the mounting connector, and the pressure sensing element blocks the drainage hole. A first annular groove surrounding the drainage hole is formed in the circumferential surface of the second end; and the outer diameter of the mounting joint corresponding to the first annular groove is smaller than the aperture of the liquid inlet. According to the miniature pressure sensor and the preparation method, the problems that an existing pressure sensor is complex in structure and large in packaging difficulty, and the installation stress borne by the pressure sensing element during riveting is too large are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a micro pressure sensor and a preparation method thereof. Background Art

[0002] The ESC brake pressure sensor, installed on the valve body of the ESC hydraulic control unit, measures brake pressure, a crucial factor in improving vehicle stability and safety. The overall structure of the hydraulic control valve requires a pressure sensor with a compact size, a pressure range of 25 MPa, and high overload and shock resistance. This requires additional components within the sensor to protect the pressure-sensing element and circuit board to improve overload and shock resistance, resulting in a complex internal structure and challenging packaging.

[0003] At the same time, the brake pressure sensor is currently installed on the hydraulic control valve body using a special "metal flow" riveting process, which involves squeezing the valve body's aviation-grade aluminum alloy into the corresponding groove of the sensor's front-end connector to form a reliable riveted connection. This riveting method results in very large installation stress, which can affect the measurement accuracy and stability of the pressure-sensing element of the brake sensor (especially the miniature brake sensor). Summary of the Invention

[0004] The main purpose of the present invention is to provide a micro pressure sensor and a preparation method, aiming to solve the problems of existing pressure sensors such as complex structure, difficult packaging and excessive installation stress on the pressure-sensitive element during riveting.

[0005] To achieve the above-mentioned objectives, the present invention proposes a miniature pressure sensor, comprising a housing, a mounting joint, a mounting structure, a circuit board and a pressure-sensitive element, wherein the mounting joint has a first end that can be riveted to a hydraulic control valve body, and also has a second end that can be connected to the pressure-sensitive element, the housing is connected to the mounting joint, the pressure-sensitive element is electrically connected to the circuit board, and both are arranged in the housing, the mounting structure is sleeved on the pressure-sensitive element, and the circuit board is mounted on the mounting joint through the mounting structure, the first end of the mounting joint is provided with a liquid inlet connected to the hydraulic control valve body, the second end is provided with a drainage hole connected to the liquid inlet, the pressure-sensitive element blocks the drainage hole, the circumferential surface of the second end is provided with a first annular groove surrounding the drainage hole, and the outer diameter of the mounting joint corresponding to the first annular groove is smaller than the aperture of the liquid inlet.

[0006] According to some embodiments of the present invention, a second annular groove is formed on the groove wall of the first annular groove near the liquid inlet, and the second annular groove extends from the groove opening toward the first end to near the liquid inlet.

[0007] According to some embodiments of the present invention, the circuit board includes a binding board, a signal conditioning board, and a contact board electrically connected to an external power supply, the binding board is electrically connected to the pressure-sensitive element, and the binding board and the contact board are both electrically connected to the signal conditioning board. The circuit board also includes a first flexible board and a second flexible board that can be bent, and the binding board, the first flexible board, the signal conditioning board, the second flexible board, and the contact board are connected in sequence.

[0008] According to some embodiments of the present invention, a plurality of welding grooves are provided on the side of the binding plate at intervals along its circumference, the mounting structure includes a mounting bracket, the pressure-sensing element is located in the mounting bracket, one end of the mounting bracket is connected to the mounting joint, and the other end is provided with a plurality of welding protrusions that can be welded and fixed to the plurality of welding grooves on the binding plate.

[0009] According to some embodiments of the present invention, the mounting structure also includes a protective bracket mounted on the mounting bracket, the outer wall of the mounting bracket is provided with a plurality of mounting clips spaced apart along its circumference, the side wall of the protective bracket is provided with a plurality of bayonet holes corresponding to the positions of the plurality of mounting clips, the protective bracket and the mounting bracket are fixed by the mounting clips and the bayonet holes, the protective bracket is provided with a mounting groove for the signal conditioning board to be inserted and placed, one end of the protective bracket is provided with an avoidance opening in its axial direction for the first flexible board to pass through, and the other end is provided with a positioning portion for positioning through the positioning hole of the contact plate.

[0010] According to some embodiments of the present invention, a first step surface is formed at the second end of the mounting joint, the pressure-sensitive element includes a varistor and a pressure-sensitive steel cup welded on the first step surface, the pressure-sensitive steel cup includes a steel cup body and an elastic diaphragm, the steel cup body is penetrated by a pressure-inducing hole, the pressure-inducing hole is connected to the drainage hole, the elastic diaphragm is arranged at one end of the steel cup body away from the mounting joint and blocks the pressure-inducing hole, a stress ring is protruded from the side of the steel cup body, the varistor is connected to the end of the elastic diaphragm facing away from the stress ring, and the varistor is electrically connected to the circuit board through a bonding wire.

[0011] In addition, the present invention also provides a sensor preparation method, comprising the following steps:

[0012] Prefabricated housing, mounting structure, circuit board and pressure-sensitive components;

[0013] Determine the aspect ratio of the drainage hole of the installation joint;

[0014] Processing and installing the joint according to the aspect ratio and designed diameter of the drainage hole;

[0015] Welding the pressure-sensitive element to the second end of the mounting joint;

[0016] Fixing the circuit board on the mounting joint via the mounting structure and electrically connecting the pressure-sensitive element to the circuit board;

[0017] The housing is put on the mounting structure and the end of the housing is fixed to the mounting joint by welding to complete the preparation of the sensor.

[0018] According to some embodiments of the present invention, fixing the circuit board on the mounting joint via the mounting structure and electrically connecting the pressure-sensitive element to the circuit board includes:

[0019] Sleeve the mounting bracket of the mounting structure onto the pressure-sensitive element, and fix the mounting bracket to the mounting joint by welding;

[0020] Welding and fixing the welding grooves on the binding plate of the circuit board to the welding protrusions on the mounting joint in a one-to-one correspondence;

[0021] electrically connecting the piezoresistor of the pressure-sensitive element to the binding plate of the circuit board through bonding wires;

[0022] Put one end of the protective bracket on the mounting bracket, pass the first flexible plate through the avoidance opening of the protective bracket, and make the mounting buckles on the mounting bracket correspond to the buckles on the protective bracket and fix them;

[0023] Bend the first flexible board so that the signal conditioning board of the circuit board extends into the mounting slot of the protective bracket, and fix the signal conditioning board by using a plurality of limiting buckles spaced apart at the notches of the mounting slot;

[0024] Bend the second flexible board and pass the positioning portion on the protection bracket through the positioning hole of the contact plate so that the contact plate of the circuit board is installed and positioned at the other end of the protection bracket;

[0025] One end of the protection bracket close to the mounting bracket is welded and fixed to the mounting joint.

[0026] According to some embodiments of the present invention, the step of putting the housing on the mounting structure and welding the end of the housing to the mounting joint comprises:

[0027] Rotate the shell of the housing so that the limiting protrusion located in the shell is aligned with the limiting long hole provided at the bottom of the mounting groove of the protective bracket;

[0028] Putting the housing on the mounting structure so that the contact springs extending into the housing abut against the contact pads of the contact plate in a one-to-one correspondence;

[0029] The end of the shell is fixed to the mounting joint by welding.

[0030] According to some embodiments of the present invention, the step of sleeve-mounting the mounting bracket of the mounting structure on the pressure-sensitive element and welding and fixing the mounting bracket to the mounting joint includes:

[0031] Rotate the mounting bracket of the mounting structure so that the tangent surface of the side of the mounting bracket is aligned with the tangent surface of the side of the pressure-sensitive steel cup of the pressure-sensitive element;

[0032] Putting the mounting bracket onto the pressure-sensitive element;

[0033] Weld the end of the mounting bracket to the mounting joint

[0034] The present invention has at least the following beneficial effects:

[0035] In the present invention, the liquid to be pressure-measured flows from the hydraulic control valve body through the liquid inlet and the drainage hole in sequence into the pressure-sensitive element, the pressure-sensitive element measures the pressure and sends the detection result to the circuit board, the pressure-sensitive element is connected to the second end of the mounting joint, and the circuit board is mounted on the mounting joint through the mounting structure. Since the mounting structure is sleeved on the pressure-sensitive element, the distance between the pressure-sensitive element and the circuit board is relatively close. On the one hand, it is convenient for the wiring of the wires when the pressure-sensitive element and the circuit board are electrically connected through the wires. On the other hand, the mounting structure can simultaneously realize the installation of the circuit board and the protection of the pressure-sensitive element and the circuit board, so that no additional protective components are required in the sensor, thereby improving the integration, streamlining the internal structure of the sensor, reducing the difficulty of packaging, and providing a basis for reducing the size of the sensor. At the same time, by providing the first annular groove at the second end of the mounting joint, the outer diameter of the mounting joint corresponding to the first annular groove is smaller than the aperture of the liquid inlet, forming a localized flexible isolation zone with an extremely weak structure at the second end. During the "metal flow" riveting process, the aluminum alloy of the hydraulic control valve body is squeezed and deformed by high pressure in an attempt to bond with the first end of the mounting joint. This process generates enormous local plastic deformation and impact forces. Because the local area of ​​the second end corresponding to the first annular groove has a stiffness far lower than that of the surrounding solid parts, when the riveting force is transmitted through the first end of the mounting joint, this weak area becomes the primary deformation point, allowing for slight, controllable elastic deformation. This deformation process effectively absorbs and dissipates most of the impact stress generated by the riveting. The narrow cross-section of the flexible isolation zone greatly increases the impedance of the stress transmission path, significantly attenuating most of the stress. Only a small amount of residual stress can cross this isolation zone and be transmitted to the pressure-sensitive element connected to the second end, significantly reducing the impact of the riveting stress on the pressure-sensitive element. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 An exploded diagram of a micro pressure sensor provided by an embodiment of the present invention;

[0038] Figure 2 for Figure 1 A cross-sectional view of a micro pressure sensor in FIG.

[0039] Figure 3 for Figure 2 A partial enlarged schematic diagram;

[0040] Figure 4 for Figure 1 Schematic diagram of the welding of the installation joint and the pressure-sensitive element;

[0041] Figure 5 for Figure 1 A three-dimensional diagram of the medium pressure-sensitive steel cup;

[0042] Figure 6 for Figure 1 A three-dimensional schematic diagram of the mounting bracket;

[0043] Figure 7 for Figure 1 A three-dimensional schematic diagram of the middle protective bracket;

[0044] Figure 8 for Figure 1 A three-dimensional schematic diagram of the middle protective bracket from another perspective;

[0045] Figure 9 for Figure 1 Schematic diagram of each flexible board of the circuit board before bending;

[0046] Figure 10 for Figure 1 Schematic diagram of each flexible board of the circuit board after bending;

[0047] Figure 11 for Figure 1 Schematic diagram of the structure of the middle shell;

[0048] Figure 12 This is a schematic flow chart of a first embodiment of a sensor preparation method according to the present invention;

[0049] Figure 13This is a schematic flow chart of a second embodiment of a sensor preparation method according to the present invention;

[0050] Figure 14 This is a schematic flow chart of a third embodiment of a sensor preparation method according to the present invention;

[0051] Figure 15 Schematic diagram of the fourth embodiment of the sensor preparation method of the present invention.

[0052] Description of reference numerals:

[0053] 100-micro pressure sensor; 1-housing; 11-limiting protrusion; 12-contact spring; 13-housing; 14-base; 141-mounting hole; 2-mounting connector; 21-first end; 211-liquid inlet; 22-second end; 221-drainage hole; 23-first annular groove; 24-second annular groove; 25-first step surface; 26-second step surface; 3-mounting structure; 31-mounting bracket; 311-welding protrusion; 312-mounting buckle; 32-protective bracket; 321-bayonet; 322-mounting groove; 323-avoidance; 324-positioning Part; 325-limiting buckle; 326-limiting long hole; 4-circuit board; 41-binding board; 411-soldering groove; 412-window; 413-binding pad; 42-signal conditioning board; 421-card slot; 422-conditioning chip; 43-contact board; 431-positioning hole; 432-contact pad; 433-limiting groove; 44-first flexible board; 45-second flexible board; 5-pressure-sensing element; 51-piezoresistor; 52-pressure-sensing steel cup; 521-steel cup body; 5211-pressure-inducing hole; 522-elastic diaphragm; 523-stress ring; 6-bonding lead. DETAILED DESCRIPTION

[0054] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0055] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0056] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0057] The present invention provides a micro pressure sensor and a preparation method thereof. Figures 1 to 15 This invention provides a micro pressure sensor and a specific embodiment of its preparation method.

[0058] like Figures 1 to 4 As shown, an embodiment of the present invention provides a miniature pressure sensor 100, including a housing 1, a mounting joint 2, a mounting structure 3, a circuit board 4 and a pressure-sensitive element 5. The mounting joint 2 has a first end 21 that can be riveted to a hydraulic control valve body, and also has a second end 22 that can be connected to the pressure-sensitive element 5. The housing 1 is connected to the mounting joint 2, and the pressure-sensitive element 5 is electrically connected to the circuit board 4, and both are arranged in the housing 1. The mounting structure 3 is sleeved on the pressure-sensitive element 5, and the circuit board 4 is mounted on the mounting joint 2 through the mounting structure 3. The first end 21 of the mounting joint 2 is provided with a liquid inlet 211 connected to the hydraulic control valve body, and the second end 22 is provided with a drainage hole 221 connected to the liquid inlet 211. The pressure-sensitive element 5 is provided to block the drainage hole 221. The circumferential surface of the second end 22 is provided with a first annular groove 23 surrounding the drainage hole 221. The outer diameter of the mounting joint 2 corresponding to the first annular groove 23 is smaller than the aperture of the liquid inlet 211.

[0059] In the present invention, the liquid to be pressure-measured flows from the hydraulic control valve body through the liquid inlet 211 and the drainage hole 221 in sequence into the pressure-sensitive element 5, and the pressure-sensitive element 5 performs pressure measurement and sends the detection result to the circuit board 4, the pressure-sensitive element 5 is connected to the second end 22 of the mounting joint 2, and the circuit board 4 is mounted on the mounting joint 2 through the mounting structure 3. Since the mounting structure 3 is sleeved on the pressure-sensitive element 5, the distance between the pressure-sensitive element 5 and the circuit board 4 is relatively close. On the one hand, it is convenient for the wiring of the wires when the pressure-sensitive element 5 and the circuit board 4 are electrically connected through the wires. On the other hand, the mounting structure 3 can simultaneously realize the installation of the circuit board 4 and the protection of the pressure-sensitive element 5 and the circuit board 4, so that no additional protective components are required in the sensor, thereby improving the integration, streamlining the internal structure of the sensor, reducing the packaging difficulty, and providing a basis for reducing the size of the sensor. At the same time, by providing the first annular groove 23 at the second end 22 of the mounting joint 2, the outer diameter of the mounting joint 2 corresponding to the first annular groove 23 is smaller than the aperture of the liquid inlet 211. This forms an extremely weak localized flexible isolation zone at the second end 22. During the "metal flow" riveting process, the aluminum alloy of the hydraulic control valve body is squeezed and deformed by high pressure in an attempt to bond with the first end 21 of the mounting joint 2. This process generates enormous localized plastic deformation and impact forces. Because the local area of ​​the second end 22 corresponding to the first annular groove 23 has a much lower stiffness than the surrounding solid parts, when the riveting force is transmitted through the first end 21 of the mounting joint 2, this weak area becomes the primary deformation point, allowing for slight, controllable elastic deformation. This deformation process effectively absorbs and dissipates most of the impact stress generated by the riveting. Furthermore, the narrow cross-section of the flexible isolation zone significantly increases the impedance of the stress transmission path, significantly attenuating most of the stress. Only a small amount of residual stress can cross this isolation zone and be transmitted to the pressure-sensitive element 5 connected to the second end 22. This significantly reduces the impact of the riveting stress on the pressure-sensitive element 5.

[0060] In order to further reduce the riveting stress transmitted to the pressure-sensitive element 5, in some embodiments, as Figure 4As shown, a second annular groove 24 is formed on the groove wall of the first annular groove 23 on the side near the liquid inlet 211. The second annular groove 24 extends from the groove opening toward the first end 21 to the vicinity of the liquid inlet 211. Since the riveting stress is transmitted from the first end 21 to the second end 22, the provision of the second annular groove 24 ensures that the local area between the second annular groove 24 and the liquid inlet 211 has a stiffness far lower than that of the surrounding solid parts and a narrower cross-section. This can reduce stress transmission through slight elastic deformation and increased resistance in the stress transmission path. The second annular groove 24 and the first annular groove 23 double-reduced the transmitted stress, minimizing the impact of the riveting stress on the pressure-sensitive element 5 and ensuring the measurement accuracy and stability of the pressure-sensitive element 5.

[0061] In order to further improve the integration level, reduce the packaging difficulty, and provide a basis for reducing the size of the sensor, in some embodiments, such as Figure 1 、 Figure 9 and Figure 10 As shown, the circuit board 4 includes a binding board 41, a signal conditioning board 42, and a contact board 43 electrically connected to an external power supply. The binding board 41 is electrically connected to the pressure-sensitive element 5, and the binding board 41 and the contact board 43 are both electrically connected to the signal conditioning board 42. The circuit board 4 also includes a first flexible board 44 and a second flexible board 45 that can be bent. The binding board 41, the first flexible board 44, the signal conditioning board 42, the second flexible board 45, and the contact board 43 are connected in sequence. In this configuration, the binding board 41, the signal conditioning board 42, and the spring contact board 43 are integrally formed during manufacturing via the first flexible board 44 and the second flexible board 45. Unlike traditional solutions, there is no need to use independent binding boards 41, signal conditioning boards 42, and output boards and achieve electrical interconnection through flying wires, solder joints, or micro connectors. This greatly reduces the packaging difficulty and improves the integration level. In addition, by bending the first flexible board 44 and the second flexible board 45, the circuit board 4 can adapt to complex spatial layouts, thereby reducing the size of the sensor.

[0062] The specific structure of the mounting structure 3 is not limited, as long as the circuit board 4 can be mounted on the mounting connector 2 through the mounting structure 3. In some embodiments, such as Figure 1 、 Figure 3 、 Figure 9 and Figure 10As shown, the side of the binding plate 41 is provided with a plurality of welding grooves 411 spaced apart along its circumference. The mounting structure 3 includes a mounting bracket 31, and the pressure-sensing element 5 is located within the mounting bracket 31. One end of the mounting bracket 31 is connected to the mounting joint 2, and the other end is provided with a plurality of welding protrusions 311 that can be welded and fixed to the plurality of welding grooves 411 on the binding plate 41. With this arrangement, the welding protrusions 311 are welded to the welding grooves 411. Since the welding protrusions 311 extend into the welding grooves 411 during welding, the welding area is increased. At the same time, since the plurality of welding grooves 411 are spaced apart along the circumference of the binding plate 41, the plurality of welding protrusions 311 are also arranged correspondingly along the circumference of the mounting bracket 31. The connection strength between the binding plate 41 and the mounting bracket 31 is improved through multi-point welding. And since the binding plate 41 is electrically connected to the pressure-sensitive element 5, the mounting bracket 31 is sleeved on the pressure-sensitive element 5, which can protect the pressure-sensitive element 5 on the one hand, and on the other hand make the distance between the pressure-sensitive element 5 and the binding plate 41 smaller, facilitating the wiring of the connecting wires.

[0063] Specifically, a window 412 is formed on the binding plate 41. The binding plate 41 and the pressure-sensitive element 5 are connected via a bonding wire 6. One end of the bonding wire 6 is connected to the bonding wire 6, and the other end passes through the window 412 and is soldered to a bonding pad 413 on the binding plate 41. This arrangement prevents the bonding wire 6 from being exposed, thereby improving the stability of the electrical connection between the binding plate 41 and the pressure-sensitive element 5.

[0064] Furthermore, in some embodiments, Figure 1 、 Figure 3 、 Figure 7 、 Figure 9 and Figure 10As shown, the mounting structure 3 also includes a protective bracket 32 ​​that is sleeved on the mounting bracket 31. The outer wall of the mounting bracket 31 is provided with a plurality of mounting clips 312 spaced apart along its circumference. The side wall of the protective bracket 32 ​​is provided with a plurality of bayonet holes 321 corresponding to the positions of the plurality of mounting clips 312. The protective bracket 32 ​​and the mounting bracket 31 are fixed by the mounting clips 312 and the bayonet holes 321. The protective bracket 32 ​​is provided with a mounting groove 322 for the signal conditioning board 42 to be inserted and placed. One end of the protective bracket 32 ​​is provided with an avoidance opening 323 in its axial direction for the first flexible board 44 to pass through, and the other end is provided with a positioning portion 324 for positioning through the positioning hole 431 of the contact plate 43. First, weld and fix the binding plate 41 to the mounting bracket 31, then put the protective bracket 32 ​​on the mounting bracket 31, and let the first flexible plate 44 pass through the avoidance opening 323 to avoid interference between the first flexible plate 44 and the end of the protective bracket 32. Then, the protective bracket 32 ​​and the mounting bracket 31 are fixed by the mounting buckle 312 and the bayonet 321. After the connection between the protective bracket 32 ​​and the mounting bracket 31 is completed, bend the first flexible plate 44 so that the signal conditioning board 42 extends into the mounting groove 322. At the same time, bend the second flexible plate 45 and pass through the positioning hole 431 of the contact plate 43 through the positioning portion 324 so that the contact plate 43 is fixed to the other end of the protective bracket 32. In this arrangement, since the protective bracket 32 ​​is mounted on the mounting bracket 31, a double layer of protection is formed for the pressure-sensitive element 5, further preventing the pressure-sensitive element 5 from being affected by external impact. At the same time, after the packaging is completed, the signal conditioning board 42 is arranged in the mounting groove 322, so that the protective bracket 32 ​​can not only fix the signal conditioning board 42 and the contact plate 43, but also protect the signal conditioning board 42.

[0065] Furthermore, if Figure 1 、 Figure 3 、 Figure 7 、 Figure 9 and Figure 10 As shown, the side of the signal conditioning board 42 is provided with a plurality of slots 421 spaced apart along its circumference, and the slots of the mounting slots 322 are correspondingly provided with a plurality of limiting buckles 325, and the protective bracket 32 ​​and the signal conditioning board 42 are connected and fixed via the limiting buckles 325 and the slots 421.

[0066] Specifically, if Figure 1As shown, the signal conditioning board 42 is electrically connected to a conditioning chip 422, which is located on the side of the signal conditioning board 42 facing away from the mounting slot 322. Since the housing 1 is made of metal and the protective bracket 32 ​​is made of plastic, the conditioning chip 422 is positioned facing the inner wall of the housing 1 so that the heat generated by the conditioning chip 422 can be directly transferred to the housing 1, thereby being conducted away more quickly.

[0067] The specific structure of the housing 1 is not limited, as long as the pressure-sensitive element 5 and the circuit board 4 are arranged in the housing 1. For example, in some embodiments, Figure 1 、 Figure 2 and Figure 11 As shown, a second step surface 26 is formed on the mounting joint 2, and the second step surface 26 is located between the first end 21 and the second end 22 of the mounting joint 2. The housing 1 includes a shell 13, a base 14, a limiting protrusion 11 and a contact spring 12. The shell 13 has a accommodating cavity with two ends open. One end of the shell 13 is welded to the second step surface 26, and the other end is connected to the base 14. The base 14 can block the opening. One end of the limiting protrusion 11 is connected to the base 14, and the other end passes through the limiting groove 433 opened on the contact plate 43 and the limiting long hole 326 opened at the bottom of the mounting groove 322 in sequence. The housing 1 and the protective bracket 32 ​​are connected through the limiting protrusion 11 and the limiting long hole 326. A mounting hole 15 is opened on the base 14. One end of the contact spring 12 is electrically connected to the external power supply, and the other end passes through the mounting hole 15 and abuts against the contact pad 432 on the contact plate 43.

[0068] The specific structure of the pressure-sensitive element 5 is not limited, as long as the pressure-sensitive element 5 is connected to the second end 22 of the mounting connector 2 and can measure the pressure of the liquid input from the drainage hole 221. For example, in some embodiments, Figures 3 to 5As shown, the second end 22 of the mounting joint 2 is formed with a first step surface 25, the pressure-sensitive element 5 includes a piezoresistor 51 and a pressure-sensitive steel cup 52 welded on the first step surface 25, the pressure-sensitive steel cup 52 includes a steel cup body 521 and an elastic diaphragm 522, the steel cup body 521 is penetrated by a pressure-inducing hole 5211, the pressure-inducing hole 5211 is connected to the drainage hole 221, the elastic diaphragm 522 is arranged at one end of the steel cup body 521 away from the mounting joint 2 and blocks the pressure-inducing hole 5211, a stress ring 523 is protruded from the side of the steel cup body 521, the piezoresistor 51 is connected to one end of the elastic diaphragm 522 facing away from the stress ring 523, and the piezoresistor 51 is electrically connected to the circuit board 4 through a bonding wire 6. When the pressure-sensing steel cup 52 is welded to the first step surface 25 of the mounting joint 2, the high temperature generated by welding and the resulting thermal expansion will generate concentrated stress at the pressure-inducing hole 5211. In order to avoid the stress being transmitted to the elastic diaphragm 522 and affecting the detection accuracy and stability, the stress ring 523 is protruded from the side of the steel cup body 521. The slight elastic deformation of the stress ring 523 can absorb and dissipate most of the residual stress from the welding area, preventing it from being directly transmitted to the thinner and more sensitive elastic diaphragm 522 area.

[0069] Specifically, the varistor 51 is a silicon strain gauge, an alloy thin film resistor or a metal thick film resistor. When the varistor 51 is a silicon strain gauge, it is sintered and melted onto the elastic diaphragm 522 through glass micro-melting; when the varistor 51 is an alloy thin film resistor, ion beam sputtering thin film technology is used to form a thin film alloy resistor layer on the surface of the stainless steel elastic substrate; when the varistor 51 is a metal thick film resistor, screen printing technology is used to screen-print and sinter the thick film resistor slurry onto the elastic diaphragm 522.

[0070] Those skilled in the art will appreciate that the above structure does not limit the micro pressure sensor 100 , and the micro pressure sensor 100 may include more or fewer components than those described above, or a combination of certain components, or a different arrangement of components.

[0071] like Figure 12 As shown, an embodiment of the present invention provides a sensor preparation method, comprising the following steps:

[0072] Step S10: Prefabricate the housing 1 , the mounting structure 3 , the circuit board 4 and the pressure-sensitive element 5 .

[0073] It should be noted that when prefabricating the pressure-sensitive element 5, if the varistor 51 is a silicon strain gauge, it is sintered and melted onto the elastic diaphragm 522 through glass micro-melting; if the varistor 51 is an alloy thin film resistor, ion beam sputtering thin film technology is used to form a thin film alloy resistor layer on the surface of the stainless steel elastic substrate; if the varistor 51 is a metal thick film resistor, screen printing technology is used to screen-print the thick film resistor slurry and sinter it to form it on the elastic diaphragm 522.

[0074] Step S20: determining the aspect ratio of the drainage hole 221 of the joint 2 to be processed and installed.

[0075] It should be noted that due to the different size parameters of the drainage hole 221, the flow resistance of the input liquid medium will be different, which in turn will cause different effects of the fluctuation and impact of the liquid medium on the pressure-sensitive element 5, and will also affect the frequency response performance of the pressure-sensitive element 5. Therefore, in order to ensure that the pressure-sensitive element 5 has a certain impact resistance while having a higher frequency response performance, it is necessary to process a mounting joint 2 with a drainage hole 221 having a specific aspect ratio.

[0076] Step S30 : machining and installing the joint 2 according to the aspect ratio and the designed diameter of the drainage hole 221 .

[0077] It should be noted that, when the aspect ratio and the design diameter of the drainage hole 221 are known, the depth of the drainage hole 221 can be calculated, and the mounting joint 2 with the drainage hole 221 can be processed accordingly.

[0078] Step S40 : welding and fixing the pressure-sensitive element 5 to the second end 22 of the mounting connector 2 .

[0079] It should be noted that after welding is completed, the welded assembly of the mounting joint 2 and the pressure-sensitive element 5 needs to be subjected to high and low temperature aging to remove welding stress.

[0080] Step S50 : fixing the circuit board 4 on the mounting joint 2 via the mounting structure 3 and electrically connecting the pressure-sensitive element 5 to the circuit board 4 .

[0081] Step S60: Put the housing 1 on the mounting structure 3 and fix the end of the housing 1 to the mounting joint 2 by welding to complete the preparation of the sensor.

[0082] In the present invention, the sensor preparation method includes the following steps: prefabricating the components of the shell 1, the mounting structure 3, the circuit board 4 and the pressure-sensitive element 5; determining the aspect ratio of the drainage hole 221 of the mounting joint 2 to be processed; processing the mounting joint 2 according to the aspect ratio and the design diameter of the drainage hole 221; welding and fixing the pressure-sensitive element 5 to the second end 22 of the mounting joint 2; fixing the circuit board 4 on the mounting joint 2 through the mounting structure 3 and electrically connecting the pressure-sensitive element 5 to the circuit board 4; putting the shell 1 on the mounting structure 3 and welding and fixing the end of the shell 1 to the mounting joint 2 to complete the preparation of the sensor.

[0083] Specifically, step S20 includes:

[0084] Step S21: prefabricate a plurality of the mounting joints 2 according to the designed diameter of the drainage hole 221 and a plurality of sets of designed aspect ratios.

[0085] It should be noted that if the diameter selected for the drainage hole 221 is too small, on the one hand, processing will be difficult, and on the other hand, there will be a risk of clogging. If the diameter is too large, the hole depth of the drainage hole 221 needs to be lengthened when the aspect ratio is fixed, which may exceed the length of the mounting joint 2. At the same time, an excessively large diameter will cause the wall thickness of the mounting joint 2 to be too small, thereby reducing the impact resistance of the mounting joint 2. Therefore, the design diameter of the drainage hole 221 is generally between 0.5 mm and 1.5 mm, and the specific value is selected according to actual conditions.

[0086] Step S22: prefabricate a corresponding number of the pressure-sensitive elements 5 , and weld each pressure-sensitive element 5 to the second end 22 of each mounting joint 2 to form a plurality of assembled welded parts.

[0087] Step S23: performing impact resistance test on each of the assembled welded parts to select corresponding qualified installation joints 2 .

[0088] It should be noted that the water hammer effect can be simulated by introducing a high-pulse liquid medium into the combined welded part to observe whether the elastic diaphragm 522 of the pressure-sensing element 5 will be permanently deformed or ruptured under extreme hydraulic transient pressure. If the elastic diaphragm 522 of the pressure-sensing element 5 does not show permanent deformation or rupture after the test is completed, the corresponding installation joint 2 is judged to be a qualified installation joint 2.

[0089] Step S24: determining the aspect ratio of the drainage hole 221 of the to-be-processed mounting joint 2 according to the aspect ratios corresponding to the qualified mounting joints 2 .

[0090] It should be noted that since the larger the aspect ratio of the drainage hole 221, the stronger the impact resistance of the pressure-sensing element 5, and the worse its frequency response capability, different aspect ratios of the drainage hole 221 can be selected according to the different needs of the sensor application scenarios. For example, the micro pressure sensor 100 in the present invention is applied to the automobile customization system. It is necessary to ensure that the pressure measurement system has a certain impact resistance while having a high frequency response capability. Therefore, the smallest aspect ratio among multiple qualified installation joints 2 can be selected as the aspect ratio of the drainage hole 221 of the installation joint 2 to be processed.

[0091] refer to Figure 13 , Figure 13 Schematic diagram of the second embodiment of the sensor preparation method of the present invention.

[0092] Based on the first embodiment, the sensor preparation method of this embodiment includes, in step S50:

[0093] Step S51 : putting the mounting bracket 31 of the mounting structure 3 on the pressure-sensitive element 5 , and welding and fixing the mounting bracket 31 to the mounting joint 2 .

[0094] Step S52 : welding and fixing the welding grooves 411 on the binding plate 41 of the circuit board 4 to the welding protrusions 311 on the mounting connector 2 in a one-to-one correspondence.

[0095] Step S53 : electrically connecting the piezoresistor 51 of the pressure-sensitive element 5 to the binding plate 41 of the circuit board 4 through the bonding wires 6 .

[0096] Step S54: Put one end of the protection bracket 32 ​​on the mounting bracket 31, pass the first flexible plate 44 through the avoidance opening 323 of the protection bracket 32, and make the mounting clips 312 on the mounting bracket 31 correspond to the clips on the protection bracket 32 ​​and be fixed one by one.

[0097] Step S55: bend the first flexible board 44 so that the signal conditioning board 42 of the circuit board 4 extends into the mounting slot 322 of the protection bracket 32, and fix the signal conditioning board 42 by a plurality of limiting clips 325 spaced apart at the notches of the mounting slot 322.

[0098] It should be noted that the signal conditioning board 42 is provided with a slot 421 at a position corresponding to each of the limit buckles 325 , and the signal conditioning board 42 is fixed in the mounting slot 322 by the cooperation and limitation between each of the limit buckles 325 and the slot 421 .

[0099] Step S56 : bend the second flexible board 45 and allow the positioning portion 324 on the protection bracket 32 ​​to pass through the positioning hole 431 of the contact plate 43 so that the contact plate 43 of the circuit board 4 is installed and positioned at the other end of the protection bracket 32 ​​.

[0100] It should be noted that after the positioning portion 324 on the protection bracket 32 ​​passes through the positioning hole 431 of the contact plate 43 , the contact plate 43 is bonded and fixed to the end of the protection bracket 32 ​​.

[0101] Step S57 : Weld and fix the end of the protection bracket 32 ​​close to the mounting bracket 31 to the mounting joint 2 .

[0102] After the first and second ends of the cam 33 are in contact with each other, the cam 33 is in contact with the second end of the cam 33. The cam 33 is in contact with the second end of the cam 33. The cam 33 is in contact with the second end of the cam 33.

[0103] refer to Figure 14 , Figure 14 Schematic diagram of the process of the third embodiment of the sensor preparation method of the present invention.

[0104] Based on the above-mentioned second embodiment, the sensor preparation method of this embodiment includes, in step S60:

[0105] Step S61 : rotating the shell 13 of the housing 1 so that the limiting protrusion 11 inside the shell 13 is aligned with the limiting long hole 326 formed at the bottom of the mounting slot 322 of the protection bracket 32 ​​.

[0106] It should be noted that, since the protection bracket 32 ​​is welded and fixed to the mounting joint 2 , the rotation of the housing 1 can be limited by the cooperation between the limiting protrusion 11 and the limiting long hole 326 , so as to facilitate the subsequent welding and fixation of the end of the shell 13 .

[0107] Step S62 : The housing 13 is placed on the mounting structure 3 , so that the contact springs 12 extending into the housing 13 abut against the contact pads 432 of the contact plate 43 in a one-to-one correspondence.

[0108] Step S63: Welding and fixing the end of the shell 13 to the mounting joint 2 .

[0109] In this embodiment, the shell 13 of the housing 1 is first rotated so that the limiting protrusion 11 located in the shell 13 is aligned with the limiting long hole 326 provided at the bottom of the mounting groove 322 of the protective bracket 32, and then the shell 13 is put on the mounting structure 3 so that the contact springs 12 extending into the shell 13 are in one-to-one contact with the contact pads 432 of the contact plate 43, and finally the end of the shell 13 is welded and fixed to the mounting joint 2.

[0110] refer to Figure 15 , Figure 15 Schematic diagram of the fourth embodiment of the sensor preparation method of the present invention.

[0111] Based on the above second embodiment, the sensor preparation method of this embodiment includes, in step S51:

[0112] Step S511 : rotating the mounting bracket 31 of the mounting structure 3 so that the tangent surface of the side of the mounting bracket 31 is aligned with the tangent surface of the side of the pressure-sensitive steel cup 52 of the pressure-sensitive element 5 .

[0113] It should be noted that since the pressure-sensitive steel cup 52 is welded and fixed to the second end 22 of the mounting joint 2, aligning the cross-section of the side of the mounting bracket 31 with the cross-section of the side of the pressure-sensitive steel cup 52 of the pressure-sensing element 5 can limit the rotation of the mounting bracket 31, thereby facilitating the subsequent welding and fixation of the mounting bracket 31.

[0114] Step S512 : putting the mounting bracket 31 on the pressure-sensitive element 5 .

[0115] Step S513 : welding the end of the mounting bracket 31 to the mounting joint 2 .

[0116] In this embodiment, the mounting bracket 31 of the mounting structure 3 is first rotated so that the cross-section of the side of the mounting bracket 31 is aligned with the cross-section of the side of the pressure-sensing steel cup 52 of the pressure-sensing element 5 to limit the rotation of the mounting bracket 31 and facilitate the subsequent welding and fixation of the mounting bracket 31. Then, the mounting bracket 31 is put on the pressure-sensing element 5, and finally the end of the mounting bracket 31 is welded to the mounting joint 2.

[0117] It should be understood that, although the various steps in the flowcharts of the embodiments of the present invention are shown in sequence as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they may be performed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily performed at the same time, but may be performed at different times, and their execution order is not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A miniature pressure sensor, characterized in that: It includes a shell, a mounting joint, a mounting structure, a circuit board and a pressure-sensitive element, the mounting joint has a first end that can be riveted to the hydraulic control valve body, and also has a second end that can be connected to the pressure-sensitive element, the shell is connected to the mounting joint, the pressure-sensitive element is electrically connected to the circuit board, and both are arranged in the shell, the mounting structure is sleeved on the pressure-sensitive element, and the circuit board is installed on the mounting joint through the mounting structure, the first end of the mounting joint is provided with a liquid inlet connected to the hydraulic control valve body, the second end is provided with a drainage hole connected to the liquid inlet, the pressure-sensitive element blocks the drainage hole, the circumferential surface of the second end is provided with a first annular groove surrounding the drainage hole, and the outer diameter of the mounting joint corresponding to the first annular groove is smaller than the aperture of the liquid inlet.

2. The micro pressure sensor according to claim 1, wherein A second annular groove is formed on the groove wall of the first annular groove near the liquid inlet. The second annular groove extends from the groove opening toward the direction close to the first end to the vicinity of the liquid inlet.

3. The micro pressure sensor according to claim 1, wherein The circuit board includes a binding board, a signal conditioning board and a contact board electrically connected to an external power supply. The binding board is electrically connected to the pressure-sensitive element. The binding board and the contact board are both electrically connected to the signal conditioning board. The circuit board also includes a first flexible board and a second flexible board that can be bent. The binding board, the first flexible board, the signal conditioning board, the second flexible board and the contact board are connected in sequence.

4. The micro pressure sensor according to claim 3, wherein The side of the binding plate is provided with a plurality of welding grooves spaced apart along its circumference. The mounting structure includes a mounting bracket. The pressure-sensing element is located in the mounting bracket. One end of the mounting bracket is connected to the mounting joint, and the other end is provided with a plurality of welding protrusions that can be welded and fixed to the corresponding welding grooves on the binding plate.

5. The micro pressure sensor according to claim 4, wherein: The mounting structure also includes a protective bracket mounted on the mounting bracket, and the outer side wall of the mounting bracket is provided with a plurality of mounting clips spaced along its circumference, and the side wall of the protective bracket is provided with a plurality of bayonet holes corresponding to the positions of the plurality of mounting clips, and the protective bracket and the mounting bracket are fixed by the mounting clips and the bayonet holes, and the protective bracket is provided with a mounting groove for the signal conditioning board to be inserted and placed, and one end of the protective bracket is provided with an avoidance opening in its axial direction for the first flexible board to pass through, and the other end is provided with a positioning portion for passing through the positioning hole of the contact plate for positioning.

6. The micro pressure sensor according to claim 1, wherein A first step surface is formed at the second end of the mounting joint, the pressure-sensitive element includes a varistor and a pressure-sensitive steel cup welded on the first step surface, the pressure-sensitive steel cup includes a steel cup body and an elastic diaphragm, the steel cup body is penetrated by a pressure-inducing hole, the pressure-inducing hole is connected to the drainage hole, the elastic diaphragm is arranged at one end of the steel cup body away from the mounting joint and blocks the pressure-inducing hole, a stress ring is protruded from the side of the steel cup body, the varistor is connected to the end of the elastic diaphragm facing away from the stress ring, and the varistor is electrically connected to the circuit board through a bonding wire.

7. A sensor preparation method, characterized in that: The following steps are involved: Prefabricated housing, mounting structure, circuit board and pressure-sensitive components; Determine the aspect ratio of the drainage hole of the joint to be processed and installed; Processing and installing the joint according to the aspect ratio and designed diameter of the drainage hole; Welding the pressure-sensitive element to the second end of the mounting joint; Fixing the circuit board on the mounting joint via the mounting structure and electrically connecting the pressure-sensitive element to the circuit board; The housing is put on the mounting structure and the end of the housing is fixed to the mounting joint by welding to complete the preparation of the sensor.

8. The sensor preparation method according to claim 7, wherein: The method of fixing the circuit board on the mounting joint via the mounting structure and electrically connecting the pressure-sensitive element to the circuit board includes: Sleeve the mounting bracket of the mounting structure onto the pressure-sensitive element, and fix the mounting bracket to the mounting joint by welding; Welding and fixing the welding grooves on the binding plate of the circuit board to the welding protrusions on the mounting joint in a one-to-one correspondence; electrically connecting the piezoresistor of the pressure-sensitive element to the binding plate of the circuit board through bonding wires; Put one end of the protective bracket on the mounting bracket, pass the first flexible plate through the avoidance opening of the protective bracket, and make the mounting buckles on the mounting bracket correspond to the buckles on the protective bracket and fix them; Bend the first flexible board so that the signal conditioning board of the circuit board extends into the mounting slot of the protective bracket, and fix the signal conditioning board by using a plurality of limiting buckles spaced apart at the notches of the mounting slot; Bend the second flexible board and pass the positioning portion on the protection bracket through the positioning hole of the contact plate so that the contact plate of the circuit board is installed and positioned at the other end of the protection bracket; One end of the protection bracket close to the mounting bracket is welded and fixed to the mounting joint.

9. The sensor preparation method according to claim 8, characterized in that: Said putting the housing on the mounting structure and welding and fixing the end of the housing to the mounting joint comprises: Rotate the shell of the housing so that the limiting protrusion located in the shell is aligned with the limiting long hole provided at the bottom of the mounting groove of the protective bracket; Putting the housing on the mounting structure so that the contact springs extending into the housing abut against the contact pads of the contact plate in a one-to-one correspondence; The end of the shell is fixed to the mounting joint by welding.

10. The sensor preparation method according to claim 8, wherein: The step of sleeve the mounting bracket of the mounting structure onto the pressure-sensitive element and welding and fixing the mounting bracket to the mounting joint comprises: Rotate the mounting bracket of the mounting structure so that the tangent surface of the side of the mounting bracket is aligned with the tangent surface of the side of the pressure-sensitive steel cup of the pressure-sensitive element; Putting the mounting bracket onto the pressure-sensitive element; The end portion of the mounting bracket is welded to the mounting joint.

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