High-overpressure-resistant micro-differential pressure sensor

Abstract

The invention provides a high-overpressure-resistant micro-differential pressure sensor, which comprises a positive pressure clamping plate and a negative pressure clamping plate, and is characterized in that a sensing cavity is formed in the butt joint of the positive pressure clamping plate and the negative pressure clamping plate; the induction module comprises a first electrode fixing seat, a second electrode fixing seat and a stainless steel membrane located between the first electrode fixing seat and the second electrode fixing seat, fixed electrodes are arranged in the first electrode fixing seat and the second electrode fixing seat, and the outer edge of the stainless steel membrane is welded to the end face of the first electrode fixing seat; the first electrode fixing seat and the second electrode fixing seat are oppositely arranged in the induction cavity, and when an external medium acts on different end faces of the stainless steel diaphragm, the stainless steel diaphragm can be far away from the first electrode fixing seat or the second electrode fixing seat under the action of different pressures. The sensor provided by the invention has a small sensing coefficient and also has a single-side high overvoltage resistance capability.

Description

Technical Field

[0001] The present invention belongs to the technical field of pressure sensors, and particularly relates to a micro differential pressure sensor resistant to high overpressure. Background Art

[0002] Differential pressure type airtightness detectors are widely used in the airtightness detection of components due to their high sensitivity (0.1 Pa). The measuring range of the differential pressure sensor is generally about ±1 kPa and is used in the case of a test pressure below 2 MPa. The sensing coefficient is an important index to measure the differential pressure sensor, which represents the change in the volume of the differential pressure sensor required to measure a unit pressure. That is, the sensing coefficient of the differential pressure sensor = change in unit volume / change in unit pressure (ΔV / ΔP). The smaller the sensing coefficient of the differential pressure sensor, the stronger the ability of the sensor to sense the differential pressure, that is, the higher the sensitivity.

[0003] During the test process of the instrument, it is inevitable that the differential pressure exceeds the measuring range of the sensor. After mild overpressure, the sensor will return to the zero position within a short time after the pressure is relieved, and it will not affect the accuracy of the instrument. If there is unilateral high overpressure, the sensor will be damaged and the instrument cannot be used. The existing dry metal capacitive differential pressure sensor has the advantages of fast response, high sensitivity, and high static pressure resistance. However, in order to ensure its sensitivity, this type of sensor often needs to make the elastic diaphragm relatively thin and apply a large tension force to the elastic diaphragm, which results in low unilateral overpressure resistance of the sensor. Summary of the Invention

[0004] The present invention provides a micro differential pressure sensor resistant to high overpressure, aiming to solve the problem that the existing metal capacitive differential pressure sensor often needs to make the elastic diaphragm relatively thin and apply a large tension force to the elastic diaphragm in order to ensure its sensitivity, and such a structure results in low unilateral overpressure resistance of the sensor.

[0005] The present invention is implemented as follows. A micro differential pressure sensor resistant to high overpressure includes:

[0006] A positive pressure clamping plate and a negative pressure clamping plate, which are fixedly connected by bolts between the positive pressure clamping plate and the negative pressure clamping plate, and an induction cavity is provided at the butt joint of the positive pressure clamping plate and the negative pressure clamping plate;

[0007] An induction module, which includes a first electrode fixing seat, a second electrode fixing seat, and a stainless steel diaphragm located between the first electrode fixing seat and the second electrode fixing seat. Fixed electrodes are provided inside the first electrode fixing seat and the second electrode fixing seat, and the outer edge of the stainless steel diaphragm is welded to the end face of the first electrode fixing seat;

[0008] The first electrode fixing seat and the second electrode fixing seat are arranged oppositely in the induction cavity. The positive pressure clamping plate and the negative pressure clamping plate are respectively provided with a first flow channel and a second flow channel. The first flow channel and the second flow channel communicate with the inside of the induction cavity. When the medium introduced by the first flow channel and the second flow channel acts on different end faces of the stainless steel diaphragm through the vent holes provided on the first electrode fixing seat and the second electrode fixing seat respectively; when the external medium acts on different end faces of the stainless steel diaphragm, the stainless steel diaphragm will move away from the first electrode fixing seat or the second electrode fixing seat under different pressures.

[0009] Preferably, a stepped through groove is provided at the center of the first electrode fixing seat. An electrode insulating ring is provided in the through groove. One end of the fixed electrode away from the stainless steel diaphragm is embedded in the inner edge of the electrode insulating ring. The fixed electrode and the electrode insulating ring seal one end of the through groove away from the second electrode fixing seat, and a first pressure chamber is formed in the through groove.

[0010] Preferably, the stainless steel diaphragm is arranged on the first electrode fixing seat. The stainless steel diaphragm is arranged on the end face of the pressure chamber of the first electrode fixing seat away from the fixed electrode. The vent hole provided on the first electrode fixing seat communicates with the first pressure chamber. When the medium introduced by the first flow channel enters the first pressure chamber along the vent hole, the medium acts on the end face of the stainless steel diaphragm away from the second electrode fixing seat.

[0011] Preferably, a lead insulating tube is provided on the side wall of the first electrode fixing seat. An electrode lead is provided in the lead insulating tube. The electrode lead is electrically connected to the fixed electrode.

[0012] Preferably, the second electrode fixing seat has the same structure as the first electrode fixing seat.

[0013] Preferably, a fixed electrode and an electrode insulating ring are also provided in the second electrode fixing seat, and a second pressure chamber is formed in the second electrode fixing seat. The vent hole provided on the second electrode fixing seat communicates with the second pressure chamber. When the medium introduced by the second flow channel enters the second pressure chamber along the vent hole, the medium acts on the end face of the stainless steel diaphragm away from the second electrode fixing seat.

[0014] Preferably, a sealing ring is provided on the outer edge of the connection between the first electrode fixing seat and the second electrode fixing seat.

[0015] Preferably, a first groove is provided on the positive pressure clamping plate, and a second groove is provided on the negative pressure clamping plate. The first electrode fixing seat is arranged in the first groove, and the second electrode fixing seat is arranged in the second groove.

[0016] Preferably, the first groove and the second groove adopt a stepped structure. The first electrode fixing seat does not contact the bottom surface of the first groove, and the second electrode fixing seat does not contact the bottom surface of the second groove.

[0017] Compared with the prior art, the embodiments of the present application mainly have the following beneficial effects:

[0018] In the anti-high overpressure micro differential pressure sensor provided by the present invention, the stainless steel diaphragm is directly welded to the first electrode fixing seat, and the outer edge structure of the first electrode fixing seat is used as a support to provide a small tension force for the stainless steel diaphragm. The advantage of this design is that it can increase the stress area of the stainless steel diaphragm or increase the diaphragm thickness, enabling the sensor to have a small sensing coefficient while having the ability to resist high overpressure unidirectionally. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an anti-high overpressure micro differential pressure sensor provided by the present invention.

[0020] Figure 2 is a schematic internal structure diagram of an anti-high overpressure micro differential pressure sensor provided by the present invention.

[0021] Figure 3 is an anti-high overpressure micro differential pressure sensor provided by the present invention Figure 2 schematic diagram of the partial structure at internal position A.

[0022] Figure 4 is a schematic structural diagram of the diaphragm tensioning and fixing device in an anti-high overpressure micro differential pressure sensor provided by the present invention.

[0023] Figure 5 is a schematic internal structure diagram of the diaphragm tensioning and fixing device in an anti-high overpressure micro differential pressure sensor provided by the present invention.

[0024] Figure 6 is an anti-high overpressure micro differential pressure sensor provided by the present invention Figure 5 schematic diagram of the partial structure at internal position B.

[0025] Figure 7 is a schematic diagram of the structure after the diaphragm of the anti-high overpressure micro differential pressure sensor provided by the present invention is tensioned and fixed.

[0026] DESCRIPTION OF THE REFERENCE NUMERALS

[0027] 1. Positive pressure clamping plate; 2. Negative pressure clamping plate; 3. First electrode fixing seat; 4. Second electrode fixing seat; 5. Fixed electrode; 6. Stainless steel diaphragm; 7. Electrode insulating ring; 8. Electrode lead; 9. Lead insulating tube; 10. Clamping plate fixing screw; 11. Welding point;

[0028] 20. Diaphragm tensioning upper die; 21. Diaphragm tensioning lower die; 22. Insulating plate; 23. Spot welding negative connection block; 24. Insulating plate fastening screw; 25. Diaphragm tensioning upper die fastening screw; 26. Rubber ring. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order.

[0030] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] An embodiment of the present invention provides an anti-high overpressure micro differential pressure sensor, as Figures 1-7 shown, the anti-high overpressure micro differential pressure sensor includes:

[0032] A positive pressure clamping plate 1 and a negative pressure clamping plate 2, which are fixedly connected by bolts between the positive pressure clamping plate 1 and the negative pressure clamping plate 2. A first groove and a second groove are respectively provided on the butting surfaces of the positive pressure clamping plate 1 and the negative pressure clamping plate 2, and an induction cavity is formed at the butting portion of the first groove and the second groove; it should be noted that a first flow channel and a second flow channel are respectively provided on the positive pressure clamping plate 1 and the negative pressure clamping plate 2, and the first flow channel and the second flow channel are communicated with the inside of the induction cavity, and the medium to be measured outside will be introduced into the induction cavity from the first flow channel or the second flow channel;

[0033] An induction module, the induction module includes a first electrode fixing seat 3, a second electrode fixing seat 4 and a stainless steel diaphragm 6 attached to the end face of the first electrode fixing seat 3. Fixed electrodes 5 are provided inside the first electrode fixing seat 3 and the second electrode fixing seat 4, and the stainless steel diaphragm 6 is arranged between the first electrode fixing seat 3 and the second electrode fixing seat 4; the first electrode fixing seat 3 and the second electrode fixing seat 4 have the same structure. Here, the first electrode fixing seat 3 and the second electrode fixing seat 4 are used for distinction to facilitate those skilled in the art to understand the electrode fixing seat connected to the stainless steel diaphragm 6 and the electrode fixing seat not connected to the stainless steel diaphragm 6;

[0034] The first electrode fixing seat 3 and the second electrode fixing seat 4 are respectively embedded inside the first groove and the second groove. Fixing electrodes 5 are provided inside both the first electrode fixing seat 3 and the second electrode fixing seat 4. The medium introduced by the first flow channel or the second flow channel will act on different end faces of the stainless-steel diaphragm 6 through the vent holes provided on the first electrode fixing seat 3 and the second electrode fixing seat 4. The displacement amount of the stainless-steel diaphragm 6 between the two groups of fixing electrodes 5 is utilized to generate an electrical signal on the fixing electrodes 5, and the pressure value borne on the stainless-steel diaphragm 6 is obtained by analyzing the data of the electrical signal. The specific principle is as follows: When there is a pressure difference on both sides, the diaphragm will bend towards the side with lower pressure, changing the distance between the diaphragm and the electrode fixing electrodes, thereby changing the capacitance of the two capacitors. This change can be converted into a voltage or current signal through a measuring circuit to achieve the measurement of the pressure difference.

[0035] The stainless-steel diaphragm 6 is directly welded to the first electrode fixing seat 3. The outer edge structure of the first electrode fixing seat 3 is used to provide a tension force for the stainless-steel diaphragm 6. Since the outer edge of the stainless-steel diaphragm 6 is fixed to the first electrode fixing seat 3, different from the existing structure restricted by the electrodes, the stress area of the stainless-steel diaphragm 6 can be increased or the diaphragm thickness can be increased, enabling the sensor to have a small sensing coefficient while having the ability to resist high overpressure unilaterally.

[0036] As a preferred implementation manner in this embodiment, a stepped through groove is provided at the center of the first electrode fixing seat 3, and an electrode insulating ring 7 is provided in the through groove; a first-level support ring surface and a second-level support ring surface are provided in the through groove, and the electrode insulating ring 7 is snap-fitted with the second-level support ring surface and the side wall of the second-level support ring surface; one end of the fixing electrode 5 away from the stainless-steel diaphragm 6 is embedded in the inner edge of the electrode insulating ring 7, and after the fixing electrode 5 and the electrode insulating ring 7 are assembled together, the end of the through groove away from the second electrode fixing seat 4 is blocked, and a first pressure chamber is formed in the through groove. The fixing electrode 5 does not come into contact with the first-level support ring surface with the help of the electrode insulating ring 7. Here, the gap between the fixing electrode 5 and the through groove will be used as a part of the first pressure chamber.

[0037] In this embodiment, a lead insulating tube 9 is provided on the side wall of the first electrode fixing seat 3, and an electrode lead 8 is provided inside the lead insulating tube 9. The electrode lead 8 is electrically connected to the fixing electrode 5; the second electrode fixing seat 4 has the same structure as the first electrode fixing seat 3. Fixing electrodes 5 and an electrode insulating ring 7 are also provided inside the second electrode fixing seat 4. The fixing electrodes 5 and the electrode insulating ring 7 inside the second electrode fixing seat 4 form a second pressure chamber in the second electrode fixing seat 4.

[0038] As a preferred implementation mode in this embodiment, the stainless-steel diaphragm 6 is arranged on the first electrode fixing seat 3, and the stainless-steel diaphragm 6 is arranged on the end face of the pressure chamber of the first electrode fixing seat 3 far away from the fixed electrode 5. The vent hole provided on the first electrode fixing seat 3 is communicated with the first pressure chamber. When the medium introduced into the first flow channel enters the first pressure chamber along the vent hole, the medium acts on the end face of the stainless-steel diaphragm 6 far away from the second electrode fixing seat 4;

[0039] The vent hole provided on the second electrode fixing seat 4 is communicated with the second pressure chamber. When the medium introduced into the second flow channel enters the second pressure chamber along the vent hole, the medium acts on the end face of the stainless-steel diaphragm 6 far away from the second electrode fixing seat 4;

[0040] In this embodiment, the medium introduced into the first flow channel or the second flow channel will finally reach different sides of the stainless-steel diaphragm 6. During the pressure test, the medium generates pressure on the stainless-steel diaphragm 6, forcing the stainless-steel diaphragm 6 to deform, and generating an electrical signal between the two groups of fixed electrodes 5 to realize the perception and measurement of the pressure value;

[0041] An outer edge of the connection between the first electrode fixing seat 3 and the second electrode fixing seat 4 is provided with a sealing ring; when the medium input into the second flow channel enters the second pressure chamber, the sealing ring seals the connection between the first electrode fixing seat 3 and the second electrode fixing seat 4 to prevent the medium in the second pressure chamber from leaking; in addition, the first flow channel and the second flow channel can only be enabled separately to avoid simultaneous pressure on both sides of the stainless-steel diaphragm 6, resulting in abnormal test data;

[0042] As a preferred implementation mode in this embodiment, the first groove and the second groove adopt a stepped structure, the first electrode fixing seat 3 does not contact the bottom surface of the first groove, and the second electrode fixing seat 4 does not contact the bottom surface of the second groove;

[0043] In a further preferred embodiment of the present invention, the space between the first electrode fixing seat 3 and the bottom surface of the first groove and the space between the second electrode fixing seat 4 and the bottom surface of the second groove will serve as channels for the medium to flow in the sensing chamber;

[0044] This application also provides a diaphragm tensioning and fixing device for tensioning the first electrode fixing seat 3 and the stainless-steel diaphragm 6 in an anti-high overpressure micro differential pressure sensor. The diaphragm tensioning and fixing device includes a diaphragm tensioning upper die 2, a diaphragm tensioning lower die 21, an insulating plate 22, a spot welding negative connection block 23, an insulating plate fastening screw 24, a diaphragm tensioning upper die fastening screw 25, and a rubber ring 26;

[0045] The specific processing method is as follows:

[0046] S1: Place the first electrode fixing seat 3 with an outer diameter of 40.4 mm inside the diaphragm tensioning lower die 21.

[0047] S2: Cut a 304 stainless steel circular sheet with an outer diameter of 62 mm and a thickness of 0.04 mm.

[0048] S3: Place the stainless steel circular sheet inside the diaphragm tensioning lower die 21.

[0049] S4: Install the diaphragm tensioning upper die 20, and tighten the fastening screw 25 of the diaphragm tensioning upper die 20. By means of the raised circular ring inside the upper die cooperating with the grooved circular ring of the lower die to extrude the stainless steel diaphragm 6, a U-shaped grooved circular ring is generated inside the stainless steel to achieve the purpose of diaphragm tensioning; as Figure 6 shown, the inner diameter of the raised circular ring of the diaphragm tensioning upper die 20 is 46 mm, the outer diameter is 49.6 mm, and the height of the convex platform is 0.15 mm.

[0050] S5: The negative connection block 23 is connected to the negative pole of the resistance welding machine, and the negative connection block 23 is connected to the diaphragm tensioning lower die 21 through the rubber ring 26; the positive electrode welding torch of the resistance welding machine performs spot welding with a multi-point uniform distribution on the stainless steel diaphragm 6 to form welding points 11, so that the stainless steel diaphragm 6 is fixed on the electrode fixing seat 44, as Figure 4 shown.

[0051] S6: Take out the welded stainless steel diaphragm 6 and the first electrode fixing seat 3, as Figure 7 shown, and cut off the excess stainless steel diaphragm 6 along the outer circle of the first electrode fixing seat 3. The cut stainless steel diaphragm 6 and the first electrode fixing seat 3 can be installed inside the differential pressure sensor.

[0052] It should be noted that for the foregoing embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps may be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the protection scope of the invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still, without conflict, make combinations, additions, deletions, or other adjustments to the features in the embodiments of the present invention according to the situation without creative efforts, so as to obtain different technical solutions that are essentially not divorced from the concept of the present invention, and these technical solutions also belong to the scope of protection of the present invention.

Claims

1. A micro differential pressure sensor resistant to high overpressure, characterized in that: include: A positive pressure splint (1) and a negative pressure splint (2), wherein a sensing cavity is provided at the joint between the positive pressure splint (1) and the negative pressure splint (2); A sensing module, the sensing module comprising a first electrode fixing seat (3), a second electrode fixing seat (4) and a stainless steel diaphragm (6) located between the first electrode fixing seat (3) and the second electrode fixing seat (4), wherein the first electrode fixing seat (3) and the second electrode fixing seat (4) are provided with fixed electrodes (5) inside, and the outer edge of the stainless steel diaphragm (6) is welded to the end surface of the first electrode fixing seat (3); The first electrode fixing seat (3) and the second electrode fixing seat (4) are arranged opposite to each other in the sensing cavity. The positive pressure clamping plate (1) and the negative pressure clamping plate (2) are respectively provided with a first flow channel and a second flow channel. The first flow channel and the second flow channel are connected to the sensing cavity. The medium introduced into the first flow channel and the second flow channel will act on different end faces of the stainless steel diaphragm (6) through the vent holes provided on the first electrode fixing seat (3) and the second electrode fixing seat (4). When the external medium acts on different end faces of the stainless steel diaphragm (6), the stainless steel diaphragm (6) will move away from the first electrode fixing seat (3) or the second electrode fixing seat (4) under the action of different pressures.

2. A high overpressure resistant micro differential pressure sensor as claimed in claim 1, characterized in that: A stepped through groove is provided at the center of the first electrode fixing seat (3), an electrode insulating ring (7) is provided in the through groove, and an end of the fixed electrode (5) away from the stainless steel diaphragm (6) is embedded in the inner edge of the electrode insulating ring (7), the fixed electrode (5) and the electrode insulating ring (7) block an end of the through groove away from the second electrode fixing seat (4), and a first pressure chamber is formed in the through groove.

3. A high overpressure resistant micro differential pressure sensor as claimed in claim 2, characterized in that: The stainless steel diaphragm (6) is arranged on the first electrode fixing seat (3), and the stainless steel diaphragm (6) is arranged on the end face of the pressure chamber of the first electrode fixing seat (3) away from the fixed electrode (5). The vent hole provided on the first electrode fixing seat (3) is connected to the first pressure chamber. When the medium introduced into the first flow channel enters the first pressure chamber along the vent hole, the medium acts on the end face of the stainless steel diaphragm (6) away from the second electrode fixing seat (4).

4. A high overpressure resistant micro differential pressure sensor as claimed in claim 3, characterized in that: A lead wire insulation tube (9) is provided on the side wall of the first electrode fixing seat (3), an electrode lead wire (8) is provided inside the lead wire insulation tube (9), and the electrode lead wire (8) is electrically connected to the fixed electrode (5).

5. A high overpressure resistant micro differential pressure sensor as claimed in claim 4, characterized in that: The second electrode fixing seat (4) has the same structure as the first electrode fixing seat (3).

6. A high overpressure resistant micro differential pressure sensor as claimed in claim 5, characterized in that: The second electrode fixing seat (4) is also provided with a fixed electrode (5) and an electrode insulating ring (7), and a second pressure chamber is formed in the second electrode fixing seat (4). The second electrode fixing seat (4) is provided with a vent hole which is connected to the second pressure chamber. When the medium introduced into the second flow channel enters the second pressure chamber along the vent hole, the medium acts on the end surface of the stainless steel diaphragm (6) away from the second electrode fixing seat (4).

7. A high overpressure resistant micro differential pressure sensor as claimed in claim 6, characterized in that: A sealing ring is provided at the outer edge of the connection between the first electrode fixing seat (3) and the second electrode fixing seat (4).

8. The high overpressure resistant micro differential pressure sensor according to claim 7, characterized in that: The positive pressure clamping plate (1) is provided with a first groove, the negative pressure clamping plate (2) is provided with a second groove, the first electrode fixing seat (3) is arranged in the first groove, and the second electrode fixing seat (4) is arranged in the second groove.

9. A high overpressure resistant micro differential pressure sensor as claimed in claim 8, characterized in that: The first groove and the second groove adopt a stepped structure; the first electrode fixing seat (3) does not contact the bottom surface of the first groove; and the second electrode fixing seat (4) does not contact the bottom surface of the second groove.

Images