Flange-mounted flat diaphragm pressure sensor

Abstract

The utility model provides a flange installation type flat diaphragm pressure sensor, which comprises a stainless steel glass sintering seat, a PCB (printed circuit board), a silicon piezoresistive chip, a flange diaphragm capsule and a threaded seat, a metal bonding pad is arranged on the surface of the silicon piezoresistive chip and is connected with a Wheatstone bridge, a flange plate is arranged on the end face of one side of the flange diaphragm capsule, a flat diaphragm is arranged on the end face of the flange plate, and the threaded seat is connected with the flange diaphragm. A mounting hole is formed in the end face of the other side of the flange diaphragm capsule, the stainless steel glass sintering seat is mounted in the mounting hole, a slim hole is formed in the center of the flange diaphragm capsule, one end of the slim hole is communicated with an oil filling cavity of the stainless steel glass sintering seat from the flat diaphragm to the other end, and a threaded seat is mounted at one end, far away from the flange plate, of the flange diaphragm capsule. The sensor has the advantages of being easy to install, convenient to use, high in interchange capacity and the like, is more suitable for occasions with requirements for cleanliness or high medium viscosity, and meanwhile is easy to clean and maintain.

Description

Technical Field

[0001] The utility model mainly relates to the technical field related to sensors, in particular to a flange-mounted flat diaphragm pressure sensor. Background Art

[0002] As a general product in the fields of fluid monitoring and measurement, automatic control and environmental monitoring, steel-sealed pressure sensors are widely used in the measurement of liquid level, flow, pressure, etc., providing effective measurement and monitoring means for industrial and production fields. Different product appearances will be used in different fields. Flanges are common components for connecting pipes / containers and equipment. Their main function is to provide a stable fixed platform to prevent the sensor from vibrating or moving.

[0003] In the prior art, the main structure of the pressure sensor with flange mounting structure is generally flange diaphragm box + finished steel-sealed pressure sensor. The finished steel-sealed pressure sensor is welded to the flange diaphragm box, and then refilled with oil to form a new steel-sealed pressure sensor, commonly known as a secondary oil-filled sensor. This type of sensor has the following disadvantages: 1. The amount of oil filling is large; 2. Because of the error of the steel-sealed pressure sensor, the performance of this type of product is worse than that of the once-filled oil product; 3. The cost is high; 4. It is impossible to develop high-performance products. Utility Model Content

[0004] In order to solve the shortcomings of current technology, the utility model combines the existing technology and, based on practical applications, provides a flange-mounted flat diaphragm pressure sensor. This type of pressure sensor only needs to be filled with oil once, has no external error superposition, has the characteristics of small oil filling volume, can reduce costs and produce products with high precision.

[0005] The technical solution of the utility model is as follows:

[0006] A flange-mounted flat diaphragm pressure sensor comprises a stainless steel glass sintering seat and a PCB board. An oil-filling cavity and a silicon piezoresistive chip are arranged in the stainless steel glass sintering seat. The oil-filling cavity is provided with an oil-filling hole for filling silicone oil, and the oil-filling hole is closed by a steel ball. A metal pad is arranged on the surface of the silicon piezoresistive chip to connect a Wheatstone bridge. The sensor also comprises a flange diaphragm box and a threaded seat. A flange is arranged on one end face of the flange diaphragm box, a flat diaphragm is arranged on the end face of the flange, and a mounting hole is arranged on the other end face of the flange diaphragm box. The stainless steel glass sintering seat is installed in the mounting hole. A fine hole is provided in the center of the flange diaphragm box, and one end of the fine hole is connected to the flat diaphragm and the other end is connected to the oil-filling cavity of the stainless steel glass sintering seat. A threaded seat is installed on the end of the flange diaphragm box away from the flange.

[0007] Furthermore, the flat diaphragm is a corrugated flat diaphragm.

[0008] Furthermore, the stainless steel glass sintering seat and the flange membrane box are connected as one through laser welding.

[0009] Furthermore, a positioning platform is provided on the flange membrane box, and a positioning hole is provided at one end of the threaded seat. The threaded seat and the flange membrane box are positioned through the positioning hole and the positioning platform, and are connected as a whole at the joint by laser welding.

[0010] Furthermore, the stainless steel glass sintering seat is provided with gold-plated pins, and the metal pads of the silicon piezoresistive chip are connected to the gold-plated pins through gold wires or aluminum wires. The PCB board is installed on the gold-plated pins at the rear end of the stainless steel glass sintering seat, and signal transmission is achieved through high-temperature wires, which pass through the internal through holes of the threaded seat.

[0011] Furthermore, a chip resistor is welded on the PCB board.

[0012] Furthermore, the silicon piezoresistive chip is bonded to the center of the stainless steel glass sintering seat by means of silica gel.

[0013] Beneficial effects of the utility model:

[0014] 1. The utility model has a flange installation at one end and a threaded joint at the other end. It has the advantages of simple structure, easy use, wide application scenarios, strong versatility, etc. The structural design of the pressure sensor only requires one-time filling of oil, no external error superposition, and has the characteristics of small oil filling volume, which can reduce costs and produce products with high precision.

[0015] 2. The utility model adopts a corrugated flat diaphragm structure arranged at the flange, which is more suitable for occasions with high cleanliness requirements or high medium viscosity. Its structural design makes the sensor easy to clean and maintain.

[0016] 3. The design of the final welded threaded seat of the utility model can change the thread specifications according to customer needs, which reduces the company's stocking costs.

[0017] 4. The two welds in the utility model product are both laser welded, and laser welding is cold welding, which has little effect on the silicon piezoresistive chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Attached Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0019] Attached Figure 2 for Figure 1 Enlarged view of the structure of part I in the middle.

[0020] Attached Figure 3 A flow chart is prepared for the utility model product.

[0021] The numbers shown in the figure are: 1. Flange diaphragm box; 2. Flat diaphragm; 3. Fine hole; 4. Silicone oil; 5. Threaded seat; 6. High-temperature wire; 7. Two welding positions; 8. Heat shrink tube; 9. Stainless steel glass sintering seat; 10. Silicon piezoresistive chip; 11. Mounting hole; 12. Oil-filled cavity; 13. Gold wire or aluminum wire; 14. Gold-plated pin; 15. Steel ball; 16. PCB board; 17. Chip resistor. DETAILED DESCRIPTION

[0022] The utility model is further described in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the utility model and are not used to limit the scope of the utility model. In addition, it should be understood that after reading the content taught by the utility model, those skilled in the art can make various changes or modifications to the utility model, and these equivalent forms also fall within the scope defined by this application.

[0023] like Figure 1 , Figure 2 As shown, a flange-mounted flat diaphragm pressure sensor provided in this embodiment.

[0024] The flange-mounted flat diaphragm pressure sensor of the present embodiment mainly comprises a flange diaphragm box 1, a flat diaphragm 2, a threaded seat 5, a stainless steel glass sintered seat 9, a PCB board 16 and the like.

[0025] Among them, an oil-filled cavity 12 and a silicon piezoresistive chip 10 are arranged in the stainless steel glass sintering seat 9. The oil-filled cavity 12 has an oil-filled hole, which connects the oil-filled cavity 12 with the atmosphere. Silicone oil 4 is poured into the oil-filled hole and sealed by a steel ball 15. The silicon piezoresistive chip 10 is bonded to the center of the stainless steel glass sintering seat 9 by silicone. A metal pad is arranged on the surface of the silicon piezoresistive chip 10 to connect the Wheatstone bridge. A gold-plated pin 14 is arranged on the stainless steel glass sintering seat 9. The metal pad of the silicon piezoresistive chip 10 is connected to the gold-plated pin 14 by a gold wire or an aluminum wire 13. The PCB board 16 is installed on the gold-plated pin at the rear end of the stainless steel glass sintering seat 9, on which a chip resistor 17 is welded. The PCB board 16 transmits the signal through the high-temperature wire 6. The above structure constitutes the main part of the pressure sensor.

[0026] In this embodiment, the flange diaphragm box 1 is mainly used to install the sensor. A flange is provided on one end of the flange diaphragm box 1, and a flat diaphragm 2 is provided on the end of the flange. A mounting hole 11 is provided on the other end of the flange diaphragm box 1, and the stainless steel glass sintering seat 9 is installed in the mounting hole 11. A fine hole 3 is provided in the center of the flange diaphragm box 1, and one end of the fine hole 3 is connected to the flat diaphragm 2 and the other end is connected to the oil filling 12 of the stainless steel glass sintering seat 9. In this structure, the flange diaphragm box 1 is mainly used to be conveniently connected to the corresponding position of the pipeline or equipment through the flange. The pressure of the liquid medium acts on the flat diaphragm 2, and the signal is transmitted to the silicon piezoresistive chip 10 through the silicone oil in the flat diaphragm 2 and the fine hole 3, so as to generate a pressure signal. A threaded seat 5 is installed at the end of the flange diaphragm box 1 away from the flange. The threaded seat 5 is a reserved joint. The threaded seat 5 can facilitate customers to install the meter head or other components.

[0027] In this embodiment, the flat diaphragm 2 is a corrugated flat diaphragm, which has higher sensitivity and is more suitable for occasions with high cleanliness requirements or high medium viscosity, and is easy to clean and maintain.

[0028] In this embodiment, the stainless steel glass sintering seat 9 and the flange membrane box 1 are connected as a whole by laser welding, and a positioning platform is provided on the flange membrane box 1, and a positioning hole is provided at one end of the threaded seat 5. After the flange membrane box 1 and the threaded seat 5 are positioned and assembled, laser welding is used to integrate them at the combined position. The two welding positions 7 refer to Figure 1 As shown in the figure, the two welds in the product are both laser welded, which is a cold weld and has little effect on the silicon piezoresistive chip.

[0029] The preparation method of the sensor provided in this embodiment can refer to Figure 3 shown.

[0030] The preparation method of the pressure sensor consists of the following processes: dispensing glue - patch - drying and curing chip - lead - welding base - oil filling - sealing welding - temperature shock - pressure shock - initial test - glue coating - welding PCB (data processing - resistance compensation) - final test - welding installation thread. The process methods are described as follows:

[0031] Apply glue at the center of the stainless steel glass sintering seat 9 to bond the silicon piezoresistive chip 10 to the stainless steel glass sintering seat 9 through glue;

[0032] The adhesive is cured by high temperature, and the metal pad of the silicon piezoresistive chip 10 is connected to the gold-plated pin 14 on the stainless steel glass sintering seat 9 by a gold wire or an aluminum wire 13 to form a lead;

[0033] The flange membrane box 1 is provided with a mounting hole 11, and the lower end of the stainless steel glass sintering seat 9 is positioned with the flange membrane box 1 through the mounting hole 11, and the two are integrated by laser welding;

[0034] The welded product and the steel ball 15 are placed in a heated vacuum environment for vacuum treatment, and the silicone oil 4 is vacuum pre-extracted. A certain height difference is maintained between the silicone oil 4 and the product. When the time and vacuum value specified by the process are reached, the oil is drained and filled. The silicone oil 4 enters the oil filling cavity 12 from the oil filling hole under the action of the pressure difference until the oil level is higher than all the oil filling holes and the oil is drained.

[0035] Before sealing welding, the steel ball 15 is placed in the oil filling hole, and the steel ball 15 and the oil filling hole are sealed together by resistance welding;

[0036] Temperature shock: After cleaning the oil-filled product, place it in a high-temperature oven and keep it at 100°C for more than 6 hours;

[0037] Pressure shock: Assemble the product to the pressure fixture, set the shock pressure value and keep it for more than 16 hours;

[0038] Initial test and data processing: Connect the product to a 1mA constant current source or a 3.3V constant voltage source to collect its signal output and determine its resistance compensation value;

[0039] Glue coating: The root of the rear end pin of the stainless steel glass sintering seat 9 is coated with silicone to prevent moisture;

[0040] Resistance compensation: Based on the result of the initial test data processing, the chip resistor 17 is soldered to the pad on the PCB board 16 by an electric soldering iron;

[0041] Soldering PCB: Six round holes are provided on the PCB board 16, which correspond to the round holes of the pins on the stainless steel glass sintering seat 9. The PCB board 16 is installed to the stainless steel glass sintering seat 9 through the round holes and the two are soldered with an electric soldering iron;

[0042] Final test: Connect the product to a 1mA constant current source to collect its signal output and verify whether the compensation value meets the specification;

[0043] Welding threaded seat: A positioning hole is provided on the threaded seat 5, and a positioning platform is provided on the flange membrane box 1. The two are installed through the positioning, and then the two are connected by laser welding from the joint to complete the preparation of the finished product.

Claims

1. A flange mounted flat diaphragm pressure sensor, comprising a stainless steel glass sintering seat and a PCB board, wherein an oil filling cavity and a silicon piezoresistive chip are arranged in the stainless steel glass sintering seat, the oil filling cavity is provided with an oil filling hole for filling silicone oil, the oil filling hole is closed by a steel ball, and a metal pad is arranged on the surface of the silicon piezoresistive chip to connect a Wheatstone bridge, characterized in that: It also includes a flange diaphragm box and a threaded seat, wherein a flange is arranged on one end face of the flange diaphragm box, a flat diaphragm is arranged on the end face of the flange, a mounting hole is arranged on the other end face of the flange diaphragm box, the stainless steel glass sintering seat is installed in the mounting hole, a fine hole is provided in the center of the flange diaphragm box, one end of the fine hole is connected to the flat diaphragm, and the other end is connected to the oil filling cavity of the stainless steel glass sintering seat, and a threaded seat is installed at the end of the flange diaphragm box away from the flange.

2. The flange mounted flat diaphragm pressure sensor according to claim 1, characterized in that: The flat diaphragm is a corrugated flat diaphragm.

3. The flange mounted flat diaphragm pressure sensor according to claim 1, characterized in that: The stainless steel glass sintering seat and the flange membrane box are connected as one body through laser welding.

4. The flange mounted flat diaphragm pressure sensor according to claim 1, characterized in that: The flange diaphragm box is provided with a positioning platform, and one end of the threaded seat is provided with a positioning hole. The threaded seat and the flange diaphragm box are positioned through the positioning hole and the positioning platform, and are connected as a whole at the joint by laser welding.

5. The flange mounted flat diaphragm pressure sensor according to claim 1, characterized in that: The stainless steel glass sintering seat is provided with gold-plated pins, and the metal pads of the silicon piezoresistive chip are connected to the gold-plated pins through gold wires or aluminum wires. The PCB board is installed on the gold-plated pins at the rear end of the stainless steel glass sintering seat, and signal transmission is achieved through high-temperature wires, which pass through the internal through holes of the threaded seat.

6. The flange mounted flat diaphragm pressure sensor according to claim 1, characterized in that: The PCB board is welded with a chip resistor.

7. The flange mounted flat diaphragm pressure sensor according to claim 1, characterized in that: The silicon piezoresistive chip is bonded to the center of the stainless steel glass sintering seat through silica gel.

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