Split type differential pressure measuring device

Abstract

The utility model provides a split type differential pressure measuring device, and relates to the technical field of pressure measurement. The device comprises a high-voltage end measuring module, a low-voltage end measuring module and a differential signal processing unit. The high-voltage end measuring module and the low-voltage end measuring module are in a physical separation structure and are respectively connected with the differential signal processing unit through cables. The differential signal processing unit comprises a double-path signal sampling circuit, a difference value operation processor and a communication interface. The two-way signal sampling circuit is connected with the high-voltage end measuring module and the low-voltage end measuring module, the output end of the two-way signal sampling circuit is connected with the difference value operation processor, and the difference value operation processor outputs pressure difference value signals through a communication interface. The device solves the technical problems that a traditional integrated differential pressure transmitter is low in measurement precision and difficult in modular maintenance, the measurement precision is remarkably improved, modular maintenance is achieved, and meanwhile the anti-interference capacity and the long-distance transmission stability are enhanced.

Description

TECHNICAL FIELD

[0001] The utility model relates to pressure measurement technical field, specifically, relate to a split type differential pressure measuring device. BACKGROUND

[0002] In the field of petrochemical industry, intelligent water affairs, differential pressure measurement needs to adapt to high and low pressure end long distance separation scene (such as oil pipeline head and tail, water supply network pressurizing station and user end). The traditional integrated differential pressure transmitter is designed with high integration, and the physical structure limitation leads to that the maximum deployment distance of high and low pressure sensors is less than 10 meters, which cannot meet the kilometer level separation point pressure difference monitoring demand, and seriously restricts the expansion of industrial monitoring scene.

[0003] The existing improvement scheme tries to expand the installation distance by extending the signal cable, but new defects are exposed: 1) when the analog signal (4-20mA) is transmitted at a long distance, the attenuation and electromagnetic interference are superimposed, and the error rate is more than 0.5% FS; 2) the sensor and the processing unit are strongly coupled, and the whole machine needs to be replaced when a single module fails, which greatly increases the maintenance cost; 3) after split deployment, the high and low pressure ends cannot be independently compensated due to the environmental temperature difference (such as high temperature pipeline end and normal temperature storage tank end). Essentially, the traditional technology has not broken through the contradiction between "split physical structure" and "signal accuracy / reliability".

[0004] In summary, how to solve the technical problems of low measurement accuracy and difficult modular maintenance of traditional integrated differential pressure transmitter is a technical problem urgently needed to be solved in the field. UTILITY MODEL CONTENT

[0005] The main purpose of the utility model is to provide a split type differential pressure measuring device to at least solve the technical problems of low measurement accuracy and difficult modular maintenance of traditional integrated differential pressure transmitter, significantly improve the measurement accuracy, realize modular maintenance, and enhance the anti-interference ability and long distance transmission stability.

[0006] In order to achieve the above purpose, the utility model provides a split type differential pressure measuring device, which comprises:

[0007] High pressure end measurement module, low pressure end measurement module and differential signal processing unit;

[0008] The high pressure end measurement module and the low pressure end measurement module are physically separated structures, and the high pressure end measurement module and the low pressure end measurement module are connected with the differential signal processing unit through cables respectively;

[0009] The differential signal processing unit comprises a double-channel signal sampling circuit, a difference operation processor and a communication interface, the input ends of the double-channel signal sampling circuit are connected with the high-voltage end measurement module and the low-voltage end measurement module respectively, the output end of the double-channel signal sampling circuit is connected with the difference operation processor, and the difference operation processor outputs a pressure difference value signal through the communication interface.

[0010] Specifically, the high-voltage end measurement module comprises a first pressure sensor, a first analog conditioning circuit, a first sealed shell and a first threaded interface.

[0011] The first pressure sensor is fixed in the first sealed shell, the sensing end of the first pressure sensor is in communication with the first threaded interface, the input end of the first analog conditioning circuit is connected with the first pressure sensor, and the output end of the first analog conditioning circuit is connected with the differential signal processing unit through the cable.

[0012] Specifically, the first sealed shell has an IP67 protection level, and the first threaded interface has an M20x1.5 standard threaded structure.

[0013] Specifically, the low-voltage end measurement module comprises a second pressure sensor, a second analog conditioning circuit, a second sealed shell and a second threaded interface.

[0014] The second pressure sensor is fixed in the second sealed shell, the sensing end of the second pressure sensor is in communication with the second threaded interface, the input end of the second analog conditioning circuit is connected with the second pressure sensor, and the output end of the second analog conditioning circuit is connected with the differential signal processing unit through the cable.

[0015] Specifically, the low-voltage end measurement module further comprises an independent power supply, and the independent power supply is electrically connected with the second analog conditioning circuit.

[0016] Specifically, the double-channel signal sampling circuit comprises a first current sampling unit and a second current sampling unit, and the first current sampling unit and the second current sampling unit are connected with the current output ends of the first analog conditioning circuit and the second analog conditioning circuit respectively.

[0017] Specifically, the communication interface is a Modbus RTU protocol interface, and an anti-surge protection circuit is integrated.

[0018] Specifically, the cable comprises a first cable and a second cable, two ends of the first cable are connected with the high-voltage end measurement module and the differential signal processing unit through first waterproof joints respectively, two ends of the second cable are connected with the low-voltage end measurement module and the differential signal processing unit through second waterproof joints respectively, and the first cable and the second cable are both shielded twisted pairs.

[0019] The utility model provides a kind of split type differential pressure measuring device, and the device includes high voltage end measurement module, low voltage end measurement module and differential signal processing unit.High voltage end measurement module and low voltage end measurement module adopt physical separation design, and they are connected with differential signal processing unit by cable respectively, realize the independent transmission of signal.Differential signal processing unit internally includes double-path signal sampling circuit, difference operation processor and communication interface.Double-path signal sampling circuit is responsible for the signal of high voltage end and low voltage end acquisition, and transmission to difference operation processor for processing, finally output pressure difference value signal through communication interface.The device solves the technical problem of low measurement accuracy and modular maintenance difficulty of traditional integrated differential pressure transmitter, significantly improves measurement accuracy, realizes modular maintenance, while enhancing anti-interference ability and long-distance transmission stability. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings accompanying the specification provide further understanding of the utility model, and the illustrative embodiments of the utility model and the description thereof are used to explain the utility model, and do not constitute undue limitation on the utility model.In the drawings:

[0021] Figure 1 It is according to the cross section schematic diagram of a kind of split type differential pressure measuring device optionally according to the utility model embodiment.

[0022] 10, high voltage end measurement module;20, low voltage end measurement module;30, differential signal processing unit;31, double-path signal sampling circuit;32, difference operation processor;33, communication interface;11, first pressure sensor;12, first analog conditioning circuit;13, first sealed shell;14, first threaded interface;21, second pressure sensor;22, second analog conditioning circuit;23, second sealed shell;24, second threaded interface;25, independent power supply;311, first current sampling unit;312, second current sampling unit;331, anti-surge protection circuit;40, cable;401, first cable;402, second cable;411, first waterproof joint;412, second waterproof joint. DETAILED DESCRIPTION

[0023] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.The utility model will be described in detail below with reference to the drawings and in combination with embodiments.

[0024] According to the split type differential pressure measuring device provided by the utility model embodiment, Figure 1The utility model provides a kind of split type differential pressure measuring device, the device includes: high voltage end measurement module 10, low voltage end measurement module 20 and differential signal processing unit 30;The high voltage end measurement module 10 with the low voltage end measurement module 20 is physically separated structure, and the high voltage end measurement module 10 with the low voltage end measurement module 20 is connected with the differential signal processing unit 30 by cable 40 respectively;The differential signal processing unit 30 includes two-way signal sampling circuit 31, difference operation processor 32 and communication interface 33, the input of two-way signal sampling circuit 31 is connected high voltage end measurement module 10 and low voltage end measurement module 20 respectively, the output of two-way signal sampling circuit 31 is connected the difference operation processor 32, and the difference operation processor 32 is output pressure difference value signal by the communication interface 33.This embodiment provides a kind of specific implementation of split type differential pressure measuring device.The device includes high voltage end measurement module 10, low voltage end measurement module 20, differential signal processing unit 30 and the cable 40 of connecting three.The following detailed description is carried out to each component and connection relationship:

[0025] 1. the structure and connection of high voltage end measurement module 10 and low voltage end measurement module 20

[0026] High voltage end measurement module 10 includes pressure sensor, signal amplifier, analog-digital converter and communication module.The output of pressure sensor is connected the input of signal amplifier by wire, and signal amplifier adopts low-noise operational amplifier, and millivolt level signal output by pressure sensor is amplified to volt level;The output of signal amplifier is connected the input of analog-digital converter, and analog-digital converter adopts 24-bit high-precision ADC chip, and analog signal is converted into digital signal;The output of analog-digital converter is connected the input of communication module, and communication module adopts RS485 communication protocol chip, and is used to transmit digital signal to differential signal processing unit 30 by cable 40.

[0027] The structure of low voltage end measurement module 20 is identical with high voltage end measurement module 10, including pressure sensor, signal amplifier, analog-digital converter and communication module, and each component connection mode is identical with high voltage end measurement module 10, and the difference lies in that pressure sensor is used to gather low pressure side pressure signal.High voltage end measurement module 10 and low voltage end measurement module 20 are two physically separated shells of independent encapsulation, and shell material is aluminum alloy, and silicon gel is filled in interior to enhance anti-vibration and anti-electromagnetic interference ability.

[0028] 2. the structure and connection of differential signal processing unit 30

[0029] The differential signal processing unit 30 comprises a double-channel signal sampling circuit 31, a difference operation processor 32 and a communication interface 33. The input end of the double-channel signal sampling circuit 31 is connected to the communication module of the high-pressure end measurement module 10 and the communication module of the low-pressure end measurement module 20 through a cable 40. The cable 40 adopts a shielded twisted pair, and an RJ45 or M12 industrial connector is arranged at both ends to ensure the anti-interference performance of signal transmission. The double-channel signal sampling circuit 31 is a differential amplification circuit, and two independent sampling channels are integrated inside, which synchronously sample the high-pressure end and low-pressure end signals respectively, and the sampling rate is 1 kHz. The output end of the double-channel signal sampling circuit 31 is connected to the input end of the difference operation processor 32 through a parallel data bus. The difference operation processor 32 adopts an ARM Cortex-M4 microcontroller, and a subtraction algorithm program is built-in to calculate the difference between the high-pressure end and low-pressure end signals in real time. The output end of the difference operation processor 32 is connected to the input end of the communication interface 33. The communication interface 33 adopts an RS485 or 4-20mA current loop interface to transmit the pressure difference signal to the upper computer or PLC control system.

[0030] 3. Connection mode and effect of the device as a whole

[0031] The high-pressure end measurement module 10 and the low-pressure end measurement module 20 are connected to the double-channel signal sampling circuit 31 of the differential signal processing unit 30 through the cable 40. The length of the cable 40 is 1-100 meters, and the shielding layer is grounded to suppress common-mode interference in long-distance transmission. The communication interface 33 of the differential signal processing unit 30 is connected to external equipment through a standard industrial communication cable to realize stable output of the pressure difference signal.

[0032] 4. Materials and installation mode of components

[0033] The high-pressure end measurement module 10 and the low-pressure end measurement module 20 are provided with flanges or threaded interfaces on the surface of the shell for direct installation at the measurement points of the high-pressure pipeline and the low-pressure pipeline to reduce signal delay caused by traditional pressure lead pipes. The sensitive diaphragm of the pressure sensor is made of single crystal silicon, and a silicon nitride protective layer is plated on the surface to improve corrosion resistance and long-term stability.

[0034] The split differential pressure measurement device provided by the embodiment avoids measurement errors caused by high-low voltage signal crosstalk in the traditional integrated structure through the physically separated high-pressure end measurement module 10 and low-pressure end measurement module 20. The synchronous sampling technology of the double-channel signal sampling circuit 31 combined with the subtraction algorithm of the difference operation processor 32 improves the measurement accuracy. The modular design allows individual replacement of the high-pressure end or low-pressure end measurement module to reduce maintenance costs. The shielded twisted pair cable 40 and grounding design enhance the anti-electromagnetic interference capability to ensure that the signal is not distorted within a transmission distance of 100 meters.

[0035] The following are preferred specific embodiments:

[0036] Specifically, the high-pressure end measurement module 10 comprises a first pressure sensor 11, a first analog conditioning circuit 12, a first sealed shell 13 and a first threaded interface 14.

[0037] The first pressure sensor 11 is fixed inside the first sealed shell 13, the sensing end of the first pressure sensor 11 is in communication with the first threaded interface 14, the input end of the first analog conditioning circuit 12 is connected to the first pressure sensor 11, and the output end of the first analog conditioning circuit 12 is connected to the differential signal processing unit 30 through the cable 40.

[0038] Specifically, the protection level of the first sealed shell 13 is IP67, and the first threaded interface 14 is a standard threaded structure of M20x1.5.

[0039] Specifically, the low-pressure end measurement module 20 comprises a second pressure sensor 21, a second analog conditioning circuit 22, a second sealed shell 23 and a second threaded interface 24.

[0040] The second pressure sensor 21 is fixed inside the second sealed shell 23, the sensing end of the second pressure sensor 21 is in communication with the second threaded interface 24, the input end of the second analog conditioning circuit 22 is connected to the second pressure sensor 21, and the output end of the second analog conditioning circuit 22 is connected to the differential signal processing unit 30 through the cable 40.

[0041] Specifically, the low-pressure end measurement module 20 further comprises an independent power supply 25, and the independent power supply 25 is electrically connected to the second analog conditioning circuit 22.

[0042] Specifically, the dual-channel signal sampling circuit 31 comprises a first current sampling unit 311 and a second current sampling unit 312, and the first current sampling unit 311 and the second current sampling unit 312 are respectively connected to the current output ends of the first analog conditioning circuit 12 and the second analog conditioning circuit 22.

[0043] Specifically, the communication interface 33 is a Modbus RTU protocol interface, and integrates a surge protection circuit 331.

[0044] Specifically, the cable 40 comprises a first cable 401 and a second cable 402, two ends of the first cable 401 are respectively connected to the high-pressure end measurement module 10 and the differential signal processing unit 30 through a first waterproof joint 411, two ends of the second cable 402 are respectively connected to the low-pressure end measurement module 20 and the differential signal processing unit 30 through a second waterproof joint 412, and the first cable 401 and the second cable 402 are both shielded twisted pairs.

[0045] The following is the implementation process of the preferred specific embodiment:

[0046] The preferred split differential pressure measurement device includes a high-pressure end measurement module 10, a low-pressure end measurement module 20, a differential signal processing unit 30, and a cable 40. The components and connection relationships are described in detail as follows:

[0047] 1. Structure and connection of high-pressure end measurement module 10

[0048] The high-pressure end measurement module 10 includes a first pressure sensor 11, a first analog conditioning circuit 12, a first sealed housing 13, and a first threaded interface 14. The first pressure sensor 11 is fixed inside the first sealed housing 13, and the sensing end of the first pressure sensor 11 is in communication with the first threaded interface 14, which is a M20x1.5 standard threaded structure for direct installation to the measurement point of the high-pressure pipeline. The protection level of the first sealed housing 13 is IP67, and the shell material is stainless steel, which is filled with epoxy resin glue to provide waterproof, dustproof, and mechanical impact resistance. The output end of the first pressure sensor 11 is connected to the input end of the first analog conditioning circuit 12 through a wire, and the first analog conditioning circuit 12 includes a signal amplification circuit and a filter circuit. The signal amplification circuit uses an instrumentation amplifier chip to amplify the millivolt-level voltage signal output by the first pressure sensor 11 to a standard range of 0-5V, and the filter circuit uses a second-order Butterworth low-pass filter with a cutoff frequency of 100Hz to suppress high-frequency noise; the output end of the first analog conditioning circuit 12 is connected to the differential signal processing unit 30 through the cable 40.

[0049] 2. Structure and connection of low-pressure end measurement module 20

[0050] The low-pressure end measurement module 20 includes a second pressure sensor 21, a second analog conditioning circuit 22, a second sealed housing 23, a second threaded interface 24, and an independent power supply 25. The second pressure sensor 21 is fixed inside the second sealed housing 23, and the sensing end of the second pressure sensor 21 is in communication with the second threaded interface 24, which is a M20x1.5 standard threaded structure for installation to the low-pressure pipeline. The protection level of the second sealed housing 23 is consistent with that of the first sealed housing 13. The output end of the second pressure sensor 21 is connected to the input end of the second analog conditioning circuit 22, and the circuit structure of the second analog conditioning circuit 22 is the same as that of the first analog conditioning circuit 12. The independent power supply 25 is a lithium sub-battery pack with an output voltage of 3.6V, which is connected to the power input end of the second analog conditioning circuit 22 through a wire to provide independent power for the low-pressure end measurement module 20, avoiding voltage attenuation caused by long-distance power supply. The output end of the second analog conditioning circuit 22 is connected to the differential signal processing unit 30 through the cable 40.

[0051] 3. Structure and connection of differential signal processing unit 30

[0052] The differential signal processing unit 30 comprises a dual-channel signal sampling circuit 31, a difference operation processor 32 and a communication interface 33. The dual-channel signal sampling circuit 31 comprises a first current sampling unit 311 and a second current sampling unit 312. The input end of the first current sampling unit 311 is connected to the current output end of the first analog conditioning circuit 12 of the high-voltage end measurement module 10 through the cable 40, and the input end of the second current sampling unit 312 is connected to the current output end of the second analog conditioning circuit 22 of the low-voltage end measurement module 20 through the cable 40. Both the first current sampling unit 311 and the second current sampling unit 312 are precision resistance current-voltage conversion circuits, and the conversion accuracy is ±0.05%. The output end of the dual-channel signal sampling circuit 31 is connected to the input end of the difference operation processor 32 through an I2C bus. The difference operation processor 32 adopts an STM32F407 microcontroller, and is internally provided with a subtraction operation program to calculate the difference value of the high-voltage end and the low-voltage end signals in real time at a sampling rate of 1 kHz. The communication interface 33 is a Modbus RTU protocol interface, and is integrated with a surge protection circuit 331. The surge protection circuit 331 adopts a series connection structure of a TVS diode and a gas discharge tube, and can withstand a 8 / 20 μs waveform and a 5kA surge current. The output end of the communication interface 33 is connected to an upper computer or a PLC system through an RS485 bus, and is used for outputting a pressure difference value signal.

[0053] 4. Structure of cable 40 and waterproof joint

[0054] The cable 40 comprises a first cable 401 and a second cable 402. The two ends of the first cable 401 are respectively connected to an aviation socket on the side wall of the first sealed shell 13 of the high-voltage end measurement module 10 and an input port of the differential signal processing unit 30 through first waterproof joints 411. The two ends of the second cable 402 are respectively connected to an aviation socket on the side wall of the second sealed shell 23 of the low-voltage end measurement module 20 and the input port of the differential signal processing unit 30 through second waterproof joints 412. Both the first cable 401 and the second cable 402 are shielded twisted pairs, and the core cross-sectional area is 0.5 mm 2 . The shielding layer adopts an aluminum foil wrapping plus tinned copper mesh weaving structure, and the shielding layers at the two ends are grounded through the metal shells of the first waterproof joints 411 and the second waterproof joints 412 to suppress electromagnetic interference.

[0055] The above only describes preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can be variously changed and modified. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A split-type differential pressure measuring device, characterized in that, include: High-voltage side measurement module (10), low-voltage side measurement module (20) and differential signal processing unit (30); The high-voltage end measurement module (10) and the low-voltage end measurement module (20) are physically separated, and the high-voltage end measurement module (10) and the low-voltage end measurement module (20) are respectively connected to the differential signal processing unit (30) via cables (40); The differential signal processing unit (30) includes a dual-channel signal sampling circuit (31), a difference calculation processor (32), and a communication interface (33). The input terminals of the dual-channel signal sampling circuit (31) are respectively connected to the high-pressure end measurement module (10) and the low-pressure end measurement module (20). The output terminal of the dual-channel signal sampling circuit (31) is connected to the difference calculation processor (32). The difference calculation processor (32) outputs the pressure difference signal through the communication interface (33).

2. The split-type differential pressure measuring device according to claim 1, characterized in that: The high-pressure end measurement module (10) includes a first pressure sensor (11), a first analog conditioning circuit (12), a first sealed housing (13), and a first threaded interface (14); The first pressure sensor (11) is fixed inside the first sealed housing (13). The sensing end of the first pressure sensor (11) is connected to the first threaded interface (14). The input end of the first analog conditioning circuit (12) is connected to the first pressure sensor (11). The output end of the first analog conditioning circuit (12) is connected to the differential signal processing unit (30) through the cable (40).

3. The split-type differential pressure measuring device according to claim 2, characterized in that: The first sealed housing (13) has an IP67 protection rating, and the first threaded interface (14) has an M20×1.5 standard thread structure.

4. The split-type differential pressure measuring device according to claim 2, characterized in that: The low-pressure end measurement module (20) includes a second pressure sensor (21), a second analog conditioning circuit (22), a second sealed housing (23), and a second threaded interface (24); The second pressure sensor (21) is fixed inside the second sealed housing (23). The sensing end of the second pressure sensor (21) is connected to the second threaded interface (24). The input end of the second analog conditioning circuit (22) is connected to the second pressure sensor (21). The output end of the second analog conditioning circuit (22) is connected to the differential signal processing unit (30) through the cable (40).

5. The split-type differential pressure measuring device according to claim 4, characterized in that: The low-voltage side measurement module (20) also includes an independent power supply (25), which is electrically connected to the second analog conditioning circuit (22).

6. The split-type differential pressure measuring device according to claim 4, characterized in that: The dual-channel signal sampling circuit (31) includes a first current sampling unit (311) and a second current sampling unit (312), and the first current sampling unit (311) and the second current sampling unit (312) are respectively connected to the current output terminals of the first analog conditioning circuit (12) and the second analog conditioning circuit (22).

7. The split-type differential pressure measuring device according to claim 1, characterized in that: The communication interface (33) is a Modbus RTU protocol interface and integrates a surge protection circuit (331).

8. The split-type differential pressure measuring device according to claim 1, characterized in that: The cable (40) includes a first cable (401) and a second cable (402). The two ends of the first cable (401) are connected to the high-voltage end measurement module (10) and the differential signal processing unit (30) respectively through a first waterproof connector (411). The two ends of the second cable (402) are connected to the low-voltage end measurement module (20) and the differential signal processing unit (30) respectively through a second waterproof connector (412). Both the first cable (401) and the second cable (402) are shielded twisted-pair cables.

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