Capacitive pressure sensor

Abstract

The utility model relates to a capacitive pressure sensor, which comprises a shell, a main body, an upper polar plate and a lower polar plate, the main body, the upper polar plate and the lower polar plate are arranged in the shell, a pressure sensing diaphragm is arranged on the main body, a middle column is arranged on the pressure sensing diaphragm, a movable polar plate is arranged on the middle column, and the movable polar plate is arranged between the upper polar plate and the lower polar plate. And metal protection rings are arranged on the upper polar plate and the lower polar plate. The differential capacitance principle is adopted, the movable polar plate is connected with the pressure sensing diaphragm through the middle column, and when measured pressure pushes the pressure sensing diaphragm to deform, the pressure sensing diaphragm synchronously pushes the movable polar plate to move between the upper polar plate and the lower polar plate, so that a differential structure is formed; pressure measurement is achieved by measuring capacitance changes formed by the movable polar plate, the upper polar plate and the lower polar plate, and small water level changes are accurately measured under the condition that high sensitivity, high precision and high stability are guaranteed.

Description

Technical Field

[0001] The utility model belongs to the technical field of safety monitoring and measuring instruments, and specifically relates to a capacitive pressure sensor. Background Art

[0002] Water level measurement, especially water level measurement and uplift pressure measurement of large and medium-sized dams, is the most important indicator of dam safety. The existing water level sensor measurement technology is not ideal in terms of instrument sensitivity, accuracy and stability, and cannot achieve high-precision and stable measurement of small water levels in dams. Utility Model Content

[0003] The purpose of the utility model is to propose a pressure measurement sensor based on the capacitive principle to address the defects of the prior art, which can achieve high-precision and stable measurement of small water levels.

[0004] In order to achieve the above purpose, the utility model provides a capacitive pressure sensor, including a shell and a main body, an upper electrode plate and a lower electrode plate installed in the shell, a pressure-sensitive diaphragm is installed on the main body, an intermediate column is installed on the pressure-sensitive diaphragm, an active electrode plate is installed on the intermediate column, the active electrode plate is arranged between the upper electrode plate and the lower electrode plate, and metal protective rings are provided on the upper electrode plate and the lower electrode plate.

[0005] The utility model adopts the differential capacitance principle, the movable plate is connected to the pressure-sensitive diaphragm through the middle column, the measured pressure change felt by the pressure-sensitive diaphragm is converted into the displacement of the movable plate, and then the capacitance between the movable plate and the upper plate and between the movable plate and the lower plate is changed, the capacitance ratio is measured, and the water level is measured.

[0006] The utility model further adopts the following technical solutions:

[0007] Preferably, connecting screws are installed on the pressure-sensitive diaphragm, and the upper electrode plate and the lower electrode plate are connected via the connecting screws.

[0008] Preferably, the upper electrode plate and the lower electrode plate are mounted on the edge of the pressure-sensitive diaphragm by connecting screws.

[0009] Preferably, the active electrode plate is connected to the center position of the pressure-sensitive diaphragm through an intermediate column.

[0010] Preferably, the pressure-sensitive diaphragm is in a mountain shape, the center of the pressure-sensitive diaphragm has a first screw hole matching the middle column, and the edge of the pressure-sensitive diaphragm has a second screw hole matching the support column.

[0011] In this way, the positions of the upper plate and the lower plate can be fixed by connecting the screws.

[0012] Preferably, a sealing ring is provided between the main body and the shell; and a sealing assembly is provided on the upper part of the shell.

[0013] Preferably, an annular sealing groove is formed on the outer wall of the main body, and the sealing ring is installed in the sealing groove; a stepped groove is formed on the upper outer wall of the main body, and the stepped groove matches the lower edge of the pressure-sensitive diaphragm.

[0014] Preferably, the upper electrode plate, the lower electrode plate and the movable electrode plate are ceramic plates.

[0015] Preferably, the lower surface of the upper electrode plate, the upper surface of the lower electrode plate, and the upper and lower surfaces of the movable electrode plate are respectively provided with capacitor electrodes, and the capacitor electrodes and the metal protection ring are metal coatings with stable performance.

[0016] Preferably, the metal plating layer is a gold plating layer.

[0017] The upper electrode plate, the lower electrode plate and the capacitor electrode of the movable electrode of the utility model are all gold-plated, which can not only improve the accuracy of the sensor but also prevent the capacitor electrode from being oxidized.

[0018] Preferably, the upper electrode plate and the lower electrode plate are respectively provided with three screw holes evenly distributed at 120° at the metal protective ring, and the connecting screws are fixed to the edge of the pressure-sensitive diaphragm after passing through the screw holes of the upper electrode plate and the lower electrode plate.

[0019] In the above structure, the metal protection rings of the upper plate and the lower plate are connected to the pressure-sensitive diaphragm structure through connecting screws, so that the metal protection rings of the upper plate and the lower plate are grounded through the connecting screws, which can eliminate the edge effect between the upper plate and the active plate and between the lower plate and the active plate, thereby improving the measurement accuracy of the sensor.

[0020] In the utility model, the sealing ring, the main body, the pressure-sensitive diaphragm, the lower electrode plate, the connecting screws, the movable electrode plate, the middle column, the upper electrode plate and the sealing assembly are installed in the shell to form a sealed enclosed space, which can realize both electrical shielding space and waterproof enclosed space.

[0021] The utility model adopts the differential capacitance principle, and the active plate is connected to the pressure-sensitive diaphragm through the middle column. When the measured pressure pushes the pressure-sensitive diaphragm to deform, the pressure-sensitive diaphragm synchronously pushes the active plate to move between the upper plate and the lower plate to form a differential structure. The pressure measurement is achieved by measuring the capacitance changes formed by the active plate and the upper plate and the lower plate respectively. Under the condition of ensuring high sensitivity, high precision and high stability, small water level changes can be accurately measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The utility model is further described below in conjunction with the accompanying drawings.

[0023] Figure 1It is a structural schematic diagram of the utility model.

[0024] Figure 2 It is a structural schematic diagram of the main body in the utility model.

[0025] Figure 3 It is a structural schematic diagram of the pressure-sensitive diaphragm in the utility model.

[0026] Figure 4 It is a structural schematic diagram of the upper electrode plate in the utility model.

[0027] Figure 5 It is a structural schematic diagram of the active electrode plate in the utility model.

[0028] Figure 6 It is a structural schematic diagram of the lower electrode plate in the utility model.

[0029] In the figure: 1. shell, 2. sealing ring, 3. main body, 4. pressure-sensitive diaphragm, 41. pressure-sensitive membrane, 5. lower electrode plate, 6. connecting screws, 7. movable electrode plate, 8. middle column, 9. upper electrode plate, 10. sealing assembly. DETAILED DESCRIPTION Embodiment 1

[0030] like Figure 1 As shown, a capacitive pressure sensor includes a housing 1 and a sealing ring 2, a main body 3, a pressure-sensitive diaphragm 4, a lower electrode 5, a connecting screw 6, an active electrode 7, an intermediate column 8, an upper electrode 9 and a sealing assembly 10 installed in the housing 1. The sealing ring 2 and the pressure-sensitive diaphragm 4 are installed on the main body 1, the connecting screws 6 and the intermediate column 8 are installed on the pressure-sensitive diaphragm 4, there are three connecting screws 6, the active electrode 7 is installed on the intermediate column 8, the lower electrode 5 and the upper electrode 9 are both installed on the connecting screws 6, and the active electrode 7 is located between the upper electrode 9 and the lower electrode 5. The lower surface of the upper electrode 9, the upper surface of the lower electrode 5, and the upper and lower surfaces of the active electrode 7 are respectively provided with capacitor electrodes, and the capacitor electrodes are gold-plated layers or other metal coatings with stable performance (see Figures 4 to 6 ).

[0031] In addition, a grounded metal protection ring is plated on the outer circumference of the capacitor pole on the lower surface of the upper plate 9 and the upper surface of the lower plate 5. In addition to gold plating, the metal protection ring can also be designed with other metal platings with stable performance. The metal protection ring is not connected to the capacitor pole. The capacitor poles of the three plates can also be plated with other metal platings with stable performance besides gold. Three screw holes are evenly distributed at 120 degrees on the upper surface of the lower plate 5 and the lower surface of the upper plate 9 at the metal protection ring (see FIG. Figure 4 and Figure 6), the connecting screw 6 is arranged in cooperation with the screw hole, and the connecting screw 6 passes through the screw holes of the upper electrode plate 9 and the lower electrode plate 5 and is inserted into the second screw hole of the pressure-sensitive diaphragm 4. The gold-plated grounding protective layer of the upper electrode plate 9 and the lower electrode plate 5 is grounded through the connecting screw 6, which can eliminate the edge effect of the electrode plate and improve the accuracy.

[0032] The sealing assembly 10 is installed on the upper part of the housing 1. The sealing assembly 10 is composed of a circular sealing plate and an annular sealing ring. The sealing ring is sleeved on the outer circle of the sealing plate and has an interference fit with the inner wall of the housing 1. The sealing ring 2, the main body 3, the pressure-sensitive diaphragm 4, the lower electrode plate 5, the connecting screws 6, the movable electrode plate 7, the intermediate column 8, the upper electrode plate, and the sealing assembly 10 are placed in the housing 1 to form a sealed closed space, which can realize both an electrical shielding space and a waterproof closed space.

[0033] The sealing ring 2 is arranged between the main body 3 and the housing 1. Figure 2 As shown, an annular sealing groove is formed on the outer wall of the main body 3, and the sealing ring 2 is installed in the sealing groove; a stepped groove is formed on the upper outer wall of the main body 3, and the lower edge of the pressure-sensitive diaphragm 4 is installed in the stepped groove, which plays a role in supporting the edge of the pressure-sensitive diaphragm 4 and preventing the edge of the pressure-sensitive diaphragm from deforming.

[0034] The upper electrode plate 9 and the lower electrode plate 5 are mounted on the edge of the pressure-sensitive diaphragm 4 by means of connecting screws 6. After the upper electrode plate 9 and the lower electrode plate 5 are mounted, their positions are fixed.

[0035] like Figure 3 As shown, the cross section of the pressure-sensitive diaphragm 4 is in a mountain shape, and the center position of the pressure-sensitive diaphragm 4 has a first screw hole matching the middle column 8, and the lower end of the middle column 8 is inserted into the first screw hole, so that the movable electrode 7 is connected to the center position of the pressure-sensitive diaphragm 4 through the middle column 8. The upper electrode plate 9 and the lower electrode plate 5 are installed on the edge of the pressure-sensitive diaphragm 4 through the connecting screw 6. The edge of the pressure-sensitive diaphragm 4 has a second screw hole matching the connecting screw 6, and the lower end of the connecting screw 6 is inserted into the second screw hole. The pressure-sensitive membrane 41 of the pressure-sensitive diaphragm 4 can sense pressure changes.

[0036] In addition, the upper electrode plate 9, the lower electrode plate 5, and the movable electrode plate 7 are all made of ceramic materials with stable performance, and the main body 3 and the pressure-sensitive mold 4 are all made of stainless steel materials.

[0037] When the measured pressure pushes the pressure-sensitive diaphragm 4 to deform, the pressure-sensitive diaphragm 4 synchronously pushes the active electrode 7 to move between the upper electrode 9 and the lower electrode 5 to form a differential structure. Pressure measurement is achieved by measuring the capacitance changes formed by the active electrode and the upper and lower electrodes.

[0038] In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A capacitive pressure sensor, comprising a housing, a main body, an upper plate and a lower plate installed in the housing, characterized in that: A pressure-sensitive diaphragm is installed on the main body, an intermediate column is installed on the pressure-sensitive diaphragm, a movable electrode plate is installed on the intermediate column, the movable electrode plate is arranged between an upper electrode plate and a lower electrode plate, and metal protective rings are arranged on the upper electrode plate and the lower electrode plate.

2. A capacitive pressure sensor according to claim 1, characterized in that: The pressure-sensitive diaphragm is provided with connecting screws, and the upper electrode plate is connected with the lower electrode plate through the connecting screws.

3. A capacitive pressure sensor according to claim 2, characterized in that: The upper electrode plate and the lower electrode plate are mounted on the edge of the pressure-sensitive diaphragm through connecting screws; the movable electrode plate is connected to the center position of the pressure-sensitive diaphragm through an intermediate column.

4. A capacitive pressure sensor according to claim 3, characterized in that: The pressure-sensitive diaphragm is in a mountain shape, the center of the pressure-sensitive diaphragm has a first screw hole matching the middle column, and the edge of the pressure-sensitive diaphragm has a second screw hole matching the connecting screw.

5. The capacitive pressure sensor according to claim 1, characterized in that: A sealing ring is arranged between the main body and the shell; and a sealing assembly is arranged on the upper part of the shell.

6. A capacitive pressure sensor according to claim 5, characterized in that: An annular sealing groove is formed on the outer wall of the main body, and the sealing ring is installed in the sealing groove; a stepped groove is formed on the upper outer wall of the main body, and the stepped groove matches the lower edge of the pressure-sensitive diaphragm.

7. A capacitive pressure sensor according to claim 1, characterized in that: The upper electrode plate, the lower electrode plate and the movable electrode plate are ceramic plates.

8. A capacitive pressure sensor according to claim 1 or 7, characterized in that: The lower surface of the upper electrode plate, the upper surface of the lower electrode plate, and the upper and lower surfaces of the movable electrode plate are respectively provided with capacitor electrodes, and the capacitor electrodes and the metal protection ring are metal coatings with stable performance.

9. A capacitive pressure sensor according to claim 8, characterized in that: The metal plating layer is a gold plating layer.

10. A capacitive pressure sensor according to claim 2, characterized in that: The upper electrode plate and the lower electrode plate are respectively provided with three screw holes evenly distributed at 120 degrees at the metal protection ring, and the connecting screws are fixed to the edge of the pressure-sensitive diaphragm after passing through the screw holes of the upper electrode plate and the lower electrode plate.

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