Differential pressure sensor

Abstract

The utility model discloses a differential pressure sensor which comprises a first sensitive core body, a second sensitive core body, a circuit board and a shell. The circuit board is connected with the first sensitive core body and the second sensitive core body. The shell is provided with a cavity for accommodating the first sensitive core body, the second sensitive core body and the circuit board, and the first sensitive core body and the second sensitive core body are distributed in the cavity of the shell side by side at intervals. Wherein the first sensitive core body and the second sensitive core body adopt the same core body structure. The core body structure comprises a tube socket, an annular connecting piece and a chip, and the chip adopts a back pressure type SOI (Silicon On Insulator) chip structure. The chip of the sensitive core body does not need to be packaged in the core body filled with silicone oil, the back of the chip is directly contacted with a measured medium to sense pressure, the optimized structure enables the sensitive core body not to need processes of oil filling, packaging and the like, and the reliability of the differential pressure sensor is improved.

Description

Technical Field

[0001] This utility model relates to the technical field of differential pressure transmitters, and more particularly to a differential pressure sensor. Background Technology

[0002] A differential pressure transmitter is a transmitter that measures the pressure difference between two points on its terminals and is widely used in industrial automation and process control systems. The differential pressure sensor, as the core component of the differential pressure transmitter, works by sensing the differential pressure between two pressure points and converting it into a standard electrical signal output.

[0003] Currently, the most commonly used type in the industry is the silicon piezoresistive differential pressure sensor. Its packaging structure works by sealing silicone oil inside the sensing element. Pressure is applied to a corrugated diaphragm used for isolation, and the diaphragm transmits the pressure equally to the chip through the incompressible silicone oil. However, the applicant's research has revealed a technical problem: due to the complexity of the silicone oil sealing process, there is a risk of silicone oil leakage from the sensing element, leading to sensor failure. Utility Model Content

[0004] To address the technical problems existing in the prior art, the purpose of this utility model is to provide a differential pressure sensor whose sensitive core structure design does not require oil filling, packaging, or other processes. Its core structure has great flexibility in design, and different core packaging structures can be designed according to different product structures and operating conditions.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] This utility model provides a differential pressure sensor, the differential pressure sensor comprising:

[0007] First sensitive core;

[0008] Second sensitive core;

[0009] A circuit board, which is connected to the first sensitive core and the second sensitive core;

[0010] The housing has a cavity for accommodating the first sensitive core, the second sensitive core, and the circuit board, wherein the first sensitive core and the second sensitive core are arranged side by side at intervals within the cavity of the housing;

[0011] The first sensitive core and the second sensitive core adopt the same core structure; the core structure includes a socket, an annular connector and a chip, the chip is connected to one end face of the annular connector, the lower end of the annular connector is connected to the socket, and the chip adopts a back-pressure SOI chip structure.

[0012] In a preferred embodiment, the chip is provided with a Wheatstone bridge.

[0013] In a preferred embodiment, the end of the tube seat is provided with a countersunk hole structure, the annular connector is embedded in the countersunk hole structure of the tube seat, and the chip is exposed in the countersunk hole structure of the tube seat.

[0014] In a preferred embodiment, the tube seat is made of heat-resistant titanium alloy TC11, and the annular connector is bonded to the tube seat with high-temperature AB adhesive.

[0015] In a preferred embodiment, the outer peripheral wall of the tube seat is provided with at least two sealing grooves, and the tube seat is connected to at least two O-rings. The O-rings are correspondingly disposed in the sealing grooves, and the O-rings are used for sealing between the tube seat and the outer shell.

[0016] In a preferred embodiment, the annular connector is a glass ring or a ceramic ring, and the thickness of the annular connector is greater than the thickness of the chip.

[0017] In a preferred embodiment, the circuit board has:

[0018] A high-end pressure amplification circuit, wherein the high-end pressure amplification circuit is used to connect to the first sensitive core;

[0019] A low-end pressure amplification circuit is used to connect to the second sensitive core.

[0020] A differential amplifier circuit, wherein the two input terminals of the differential amplifier circuit are respectively connected to the output terminal of the high-end pressure amplifier circuit and the output terminal of the low-end pressure amplifier circuit;

[0021] An output protection and filtering circuit is provided, which is connected to the output terminal of the differential amplifier circuit.

[0022] In a preferred embodiment, the housing includes:

[0023] A base, wherein the base is hollow to form a cavity for accommodating the first sensitive core, the second sensitive core, and the circuit board;

[0024] A cover plate, which is bolted to the base.

[0025] In a preferred embodiment, the cavity of the base has two grooves, which are adapted to install a first sensitive core and a second sensitive core.

[0026] The circuit board is positioned above the first and second sensitive cores.

[0027] In a preferred embodiment, the base is provided with a cable bundle for threading cables that connect to the circuit board.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] This invention discloses a differential pressure sensor, comprising a first sensitive core, a second sensitive core, a circuit board, and a housing. The circuit board is connected to the first and second sensitive cores. The housing has a chamber for accommodating the first and second sensitive cores and the circuit board, with the first and second sensitive cores arranged side-by-side at intervals within the chamber. The first and second sensitive cores employ the same core structure; the core structure includes a socket, an annular connector, and a chip, wherein the chip employs a back-pressure SOI chip structure. The chip is connected to one end face of the annular connector, and the lower end of the annular connector is connected to the socket.

[0030] The sensing chip of this invention does not need to be encapsulated inside a core filled with silicone oil. The back of the chip directly contacts the measured medium to sense pressure. This optimized structure eliminates the need for oil filling and encapsulation processes, improving the reliability of the differential pressure sensor. Furthermore, the chip structure offers great design flexibility, allowing for different encapsulation structures to be designed according to different product structures and operating conditions. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the differential pressure transmitter used in the differential pressure sensor of this utility model.

[0032] Figure 2 This is a cross-sectional assembly diagram of the differential pressure sensor of this utility model;

[0033] Figure 3 This is a three-dimensional schematic diagram of the core structure of the differential pressure sensor of this utility model;

[0034] Figure 4 This is a circuit diagram of the circuit board of this utility model.

[0035] In the picture:

[0036] 100 - First Sensitive Core;

[0037] 200 - Second sensitive core;

[0038] 300 - Circuit Board;

[0039] 400 - Outer shell, 410 - Base, 420 - Cover plate;

[0040] 10 - Differential pressure transmitter, 20 - Pipe socket, 30 - Ring connector, 40 - Chip. Detailed Implementation

[0041] To facilitate understanding of this utility model, the technical solutions and advantages of the utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Any mechanisms or methods not elaborated in this utility model can be referred to in the prior art. The specific structure and features of this utility model are illustrated below by way of example and should not constitute any limitation on this utility model. Furthermore, any technical feature mentioned below (including implicit or disclosed features), as well as any technical feature directly shown or implied in the figures, can be arbitrarily combined or deleted among these technical features to form more other embodiments that may not be directly or indirectly mentioned in this utility model. The accompanying drawings show preferred embodiments of this utility model. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0042] like Figure 1-3 As shown, this embodiment of the differential pressure sensor has a preferred structure.

[0043] like Figure 1 The differential pressure transmitter 10, which is the application device of the differential pressure sensor in this embodiment, is a differential pressure sensor. As the core component of the differential pressure transmitter 10, the core function of the differential pressure sensor is to convert the pressure difference into a standard electrical signal output.

[0044] like Figure 2 As shown, the differential pressure sensor includes a first sensitive core 100 and a second sensitive core 200, a circuit board 300, and a housing 400. The circuit board 300 is connected to the first sensitive core 100 and the second sensitive core 200. The housing 400 has a chamber for accommodating the first sensitive core 100, the second sensitive core 200, and the circuit board 300. The first sensitive core 100 and the second sensitive core 200 are arranged side-by-side at intervals within the chamber of the housing 400. The first sensitive core 100 and the second sensitive core 200 employ the same core structure; the core structure includes a tube seat 20, an annular connector 30, and a chip 40. The chip 40 is connected to one end face of the annular connector 30, and the lower end of the annular connector 30 is connected to the tube seat 20.

[0045] The working principle of this differential pressure sensor is based on the piezoresistive effect, sensing the pressure difference between two sides through two sensitive cores. Each sensitive core consists of a housing 20, an annular connector 30, and a chip 40. The chip 40 adopts a back-pressure SOI chip structure, directly exposed to the measured medium without the need for silicone oil isolation. When pressure is applied to the chip 40, its resistance changes linearly with the pressure difference. The circuit board 300 converts the resistance change into a standard electrical signal output, thereby achieving accurate measurement of the pressure difference. This direct-contact design avoids the failure problem caused by silicone oil leakage in traditional silicone oil-sealed structures, improving the sensor's reliability.

[0046] Understandably, the two sensitive cores use the same core structure and are arranged side by side with a gap between them through the outer shell 400, ensuring that they can independently sense the pressure on both sides.

[0047] It should be noted that chip 40 adopts a back-pressure SOI chip 40 structure. SOI technology achieves electrical isolation between the device and the substrate by introducing an insulating layer (usually silicon dioxide) between the top silicon layer and the substrate. This structure significantly reduces parasitic capacitance and leakage current, improving sensor performance. The back-pressure SOI chip 40 structure allows chip 40 to be directly exposed to the measured medium, sensing pressure changes through the piezoresistive structure on the back and converting them into an electrical signal output. The back-pressure design allows chip 40 to directly contact the measured medium, eliminating the risk of silicone oil leakage in traditional silicone oil-sealed structures, thereby improving sensor reliability; it also reduces packaging steps, lowers production costs, and increases design flexibility, enabling customization for different application scenarios.

[0048] In one specific implementation, a Wheatstone bridge is incorporated into chip 40. A Wheatstone bridge is a bridge circuit consisting of four resistors that measures changes in physical quantities by measuring changes in resistance. In differential pressure sensors, the four resistive arms of the Wheatstone bridge are typically composed of piezoresistors. When chip 40 senses a pressure change, these resistors change accordingly, causing the bridge to become unbalanced. Specifically, when a resistor in the bridge changes due to a pressure change, a voltage difference proportional to the pressure change is generated at the bridge's output. By acquiring and processing this voltage difference, the pressure change can be accurately measured. This design not only improves measurement accuracy and sensitivity but also converts minute pressure changes into easily measurable electrical signals.

[0049] like Figure 3As shown, the other parts of the core structure are consistent with those of a traditional sensor core. The selected chip 40 is bonded to the annular connector 30 using electrostatic bonding technology. Then, after annealing the gold wire, the ends of the gold wire are heated to form a spherical shape. The gold wire is then pressed together with the chip 40 to complete the inner lead bonding. The other end of the gold wire is connected to a lead plate, and finally, silver-plated copper core wire is used as the outer lead to connect to the circuit board 300.

[0050] In a specific implementation, such as Figure 4 As shown, the sensor circuit of circuit board 300 includes:

[0051] High-end pressure amplification circuit, used to connect to the first sensitive core 100.

[0052] The low-end pressure amplification circuit is used to connect to the second sensitive core 200.

[0053] The differential amplifier circuit has two input terminals connected to the output terminals of the high-end pressure amplifier circuit and the low-end pressure amplifier circuit, respectively.

[0054] Output protection and filtering circuit, which is connected to the output terminal of the differential amplifier circuit.

[0055] It should be noted that the high-end pressure amplification circuit is an important component of the sensor circuit, and its main function is to amplify the pressure signal detected by the first sensing element 100. Since the first sensing element 100 is in direct contact with the measured medium, its output signal is usually weak and needs to be boosted to a level suitable for subsequent processing by the amplification circuit. The low-end pressure amplification circuit functions similarly to the high-end circuit, but it is connected to the second sensing element 200. The second sensing element 200 is also in direct contact with the measured medium, detecting the pressure signal on the other side.

[0056] In practical implementation, the differential amplifier circuit is the core component of the differential pressure sensor circuit. Its input terminals are connected to the output terminals of the high-side and low-side pressure amplifier circuits, respectively. The main function of the differential amplifier circuit is to calculate the difference between the two pressure signals, thereby obtaining the differential pressure signal. The output protection and filtering circuit is connected to the output terminal of the differential amplifier circuit, and its main function is to protect and filter the final differential pressure signal.

[0057] In practice, the annular connector 30 is a glass ring or a ceramic ring, and the thickness of the annular connector 30 is greater than the thickness of the chip 40.

[0058] The annular connector 30 is a crucial component of the sensing element, primarily serving to connect the chip 40 to the socket 20 while providing mechanical support and electrical insulation. Traditional annular connectors 30 may be made of metal or other materials, but glass or ceramic rings offer superior insulation, chemical stability, and mechanical strength, making them particularly suitable for use in complex industrial environments. A thicker annular connector 30 provides more stable mechanical support, ensuring that the chip 40 does not deform or shift under pressure, thereby improving the sensor's measurement accuracy and repeatability.

[0059] In one specific embodiment, the end of the tube seat 20 is provided with a countersunk hole structure, and the annular connector 30 is embedded in the countersunk hole structure of the tube seat 20, with the chip 40 exposed in the countersunk hole structure of the tube seat 20. The tube seat 20 is made of heat-resistant titanium alloy TC11, and the annular connector 30 is bonded to the tube seat 20 with high-temperature AB adhesive.

[0060] Understandably, the tube socket 20 is a crucial component of the sensing core, primarily serving to provide mechanical support and protection for the chip 40 and the annular connector 30. Under complex operating conditions, the tube socket 20 needs to possess high strength, corrosion resistance, and high-temperature resistance to ensure the long-term stable operation of the sensor. Furthermore, the connection method between the annular connector 30 and the tube socket 20 directly affects the reliability and sealing performance of the sensor.

[0061] In practice, the high-temperature AB adhesive can maintain good bonding strength in high-temperature environments, ensuring a tight connection between the annular connector 30 and the pipe seat 20, and preventing loosening or detachment due to temperature changes.

[0062] In a preferred embodiment, the outer peripheral wall of the tube seat 20 is provided with at least two sealing grooves, and the tube seat 20 is connected to at least two O-rings. The O-rings are correspondingly disposed in the sealing grooves and are used for sealing between the tube seat 20 and the outer shell 400.

[0063] Understandably, the O-ring generates pre-compression force within the sealing groove through its elastic deformation, thereby tightly fitting the contact surfaces of the pipe seat 20 and the outer casing 400 to prevent fluid or gas leakage. This sealing method has a self-sealing effect; that is, under working pressure, the contact pressure of the O-ring increases with the increase of system pressure, further enhancing the sealing effect.

[0064] like Figure 2As shown, the housing 400 includes a base 410 and a cover plate 420. The base 410 is hollow, forming a cavity to accommodate the first sensitive core 100, the second sensitive core 200, and the circuit board 300; the cover plate 420 is bolted to the base 410. The cavity of the base 410 has two slots, which are adapted to mount the first sensitive core 100 and the second sensitive core 200; the circuit board 300 is disposed above the first sensitive core 100 and the second sensitive core 200.

[0065] In this field, the primary function of the housing 400 is to provide physical protection for the sensing core and circuit board 300, while ensuring the sensor's internal sealing to prevent external media (such as liquids or gases) from seeping in and affecting the sensor's performance and reliability. Furthermore, the design of the housing 400 must also consider the ease of installation, maintenance, and signal output of the sensor within the differential pressure transmitter. The circuit board 300 is positioned above the first sensing core 100 and the second sensing core 200. This layout allows the circuit board 300 to be electrically connected to the sensing core while avoiding mutual interference between the sensing core and the circuit board 300. The circuit board 300 connects to external devices via leads or interfaces to output signals.

[0066] In another specific implementation, the base 410 is equipped with a cable tie for threading the cables connecting the circuit board 300. This ensures the sealing of the cable installation and improves the overall reliability of the sensor.

[0067] The above embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of protection of the present utility model. For those skilled in the art, it will be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present utility model. The scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. A differential pressure sensor, characterized in that, The differential pressure sensor includes: First sensitive core; Second sensitive core; A circuit board, which is connected to the first sensitive core and the second sensitive core; The housing has a cavity for accommodating the first sensitive core, the second sensitive core, and the circuit board, wherein the first sensitive core and the second sensitive core are arranged side by side at intervals within the cavity of the housing; The first sensitive core and the second sensitive core adopt the same core structure; the core structure includes a socket, an annular connector and a chip, the chip is connected to one end face of the annular connector, the lower end of the annular connector is connected to the socket, and the chip adopts a back-pressure SOI chip structure.

2. A differential pressure sensor as described in claim 1, characterized in that: The chip is equipped with a Wheatstone bridge.

3. A differential pressure sensor as described in claim 1, characterized in that: The end of the tube base is provided with a countersunk hole structure, the annular connector is embedded in the countersunk hole structure of the tube base, and the chip is exposed in the countersunk hole structure of the tube base.

4. A differential pressure sensor as described in claim 3, characterized in that: The tube seat is made of heat-resistant titanium alloy TC11, and the annular connector is bonded to the tube seat with high-temperature AB adhesive.

5. A differential pressure sensor as described in claim 4, characterized in that: The outer peripheral wall of the tube seat is provided with at least two sealing grooves, and the tube seat is connected to at least two O-rings. The O-rings are correspondingly disposed in the sealing grooves, and the O-rings are used for sealing between the tube seat and the outer shell.

6. A differential pressure sensor as described in claim 1, characterized in that: The annular connector is a glass ring or a ceramic ring, and the thickness of the annular connector is greater than the thickness of the chip.

7. A differential pressure sensor as described in any one of claims 1 to 6, characterized in that, The circuit board has: A high-end pressure amplification circuit, wherein the high-end pressure amplification circuit is used to connect to the first sensitive core; A low-end pressure amplification circuit is used to connect to the second sensitive core. A differential amplifier circuit, wherein the two input terminals of the differential amplifier circuit are respectively connected to the output terminal of the high-end pressure amplifier circuit and the output terminal of the low-end pressure amplifier circuit; An output protection and filtering circuit is provided, which is connected to the output terminal of the differential amplifier circuit.

8. A differential pressure sensor as described in any one of claims 1 to 6, characterized in that, The outer casing includes: A base, wherein the base is hollow to form a cavity for accommodating the first sensitive core, the second sensitive core, and the circuit board; A cover plate, which is bolted to the base.

9. A differential pressure sensor as described in claim 8, characterized in that: The cavity of the base has two column slots, which are adapted to install the first sensitive core and the second sensitive core. The circuit board is positioned above the first and second sensitive cores.

10. A differential pressure sensor as described in claim 8, characterized in that: The base is equipped with a cable bundle for threading cables that connect to the circuit board.

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