A differential pressure gauge

Abstract

The present invention provides a differential pressure gauge, which relates to the field of flow meters, and comprises a measuring tube with a sealed cavity, a first bellows fixed in the measuring tube cavity, and an elastic sheet and a movement amplification mechanism installed outside the measuring tube, wherein the measuring tube is provided with a high-pressure channel connected to the inner cavity of the first bellows and a low-pressure channel connected to the inner cavity of the measuring tube, the first bellows has a sealed inner cavity, the first bellows is connected to the elastic sheet through a pressure-sensitive component to make the elastic sheet tilt, and the movement amplification mechanism is connected to the elastic sheet to display the differential pressure. The invention solves the problem that the pressure bearing capacity and sensitivity of the double bellows differential pressure gauge in the prior art cannot be taken into account at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of differential pressure detection, in particular to a differential pressure gauge. Background Art

[0002] Differential pressure gauges are mainly used in the filtration and purification industries to measure the differential pressure before and after the filter element to determine the degree of blockage of the filter element.

[0003] Currently, there are differential pressure gauges with two bellows on the market. When using them, high-pressure gas and low-pressure gas need to be introduced into the two bellows respectively. In order to ensure the accuracy of measurement, the pressure-sensing areas of the two bellows usually need to be set equal. When other conditions are the same, the pressure-sensing area of ​​the bellows is proportional to the square of its diameter, but the pressure-bearing capacity of the bellows is negatively correlated with its diameter. If two bellows with larger diameters are selected, their pressure-bearing capacity is poor, and if two bellows with smaller diameters are selected, their detection sensitivity is low. It can be seen that the pressure-bearing capacity and sensitivity of the existing double-bellows differential pressure gauge cannot be taken into account at the same time. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a differential pressure gauge, which solves the problem that the pressure bearing capacity and sensitivity of the double bellows differential pressure gauge in the prior art cannot be taken into account at the same time.

[0005] According to an embodiment of the present invention, a differential pressure gauge includes a measuring cylinder with a closed cavity, a first bellows fixed in the cavity of the measuring cylinder, and an elastic sheet and a movement amplifying mechanism installed outside the measuring cylinder, the measuring cylinder is provided with a high-pressure channel connected to the inner cavity of the first bellows and a low-pressure channel connected to the inner cavity of the measuring cylinder, the first bellows has a closed inner cavity, the first bellows is connected to the elastic sheet through a pressure-sensing component to make the elastic sheet tilt, and the movement amplifying mechanism is connected to the elastic sheet to display the differential pressure.

[0006] Compared with the prior art, the present invention has the following beneficial effects: when in use, the high-pressure gas and the low-pressure gas are respectively transported to the closed cavity of the first bellows and the measuring tube through the high-pressure channel and the low-pressure channel; since the first bellows is fixed in the measuring tube, the high pressure and the low pressure inside and outside the first bellows cancel each other out, and the first bellows only bears the differential pressure between the high pressure and the low pressure; the differential pressure drives the first bellows to extend upward and then lift the elastic sheet and finally display the differential pressure through the movement amplification mechanism; it can be seen that by adopting the above scheme, when a first bellows with a larger diameter is selected, the pressure-sensing area of ​​the first bellows is increased to ensure the sensitivity of the device, and the bearing pressure of the first bellows is reduced, thereby achieving a balance between sensitivity and pressure-bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0008] In the above drawings: 1. Measuring cylinder; 101. High-pressure channel; 102. Low-pressure channel; 103. End cover; 104. Pressure-sensing seat; 105. Cylinder body; 2. First bellows; 3. Elastic sheet; 4. Movement amplification mechanism; 5. Pressure-sensing assembly; 501. Pressure-sensing plate; 502. Connecting rod; 6. Second bellows; 7. Third bellows. DETAILED DESCRIPTION

[0009] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0010] like Figure 1 As shown, a differential pressure gauge comprises a measuring tube 1 with a sealed cavity, a first bellows 2 fixed in the cavity of the measuring tube 1, and an elastic sheet 3 and a movement amplifying mechanism 4 installed outside the measuring tube 1; specifically, the measuring tube 1 comprises an end cover 103, a cylinder body 105 with open ends at both ends, and an upper pressure-sensing seat 104 and a lower pressure-sensing seat 104 detachably connected to the two ends of the cylinder body 105, the number of the end covers 103 is two and they are detachably connected to the middle part of each pressure-sensing seat 104, the end cover 103, the pressure-sensing seat 104 and the cylinder body 105 are all arranged to be detachably connected to facilitate the assembly and disassembly of the parts in the measuring tube 1; it should be noted that the end cover 103, the pressure-sensing seat 104 and the cylinder body 105 are all required to be provided with a conventional sealing structure to ensure that the inner cavity of the measuring tube 1 is sealed; each of the end covers 103 is provided with an air duct connected to the outside.

[0011] The measuring tube 1 is provided with a high-pressure channel 101 connected to the inner cavity of the first bellows 2 and a low-pressure channel 102 connected to the inner cavity of the measuring tube 1, and the high-pressure channel 101 and the low-pressure channel 102 are both arranged on the lower pressure-sensing seat 104; the first bellows 2 has a closed inner cavity. In order to facilitate the fixation and sealing of the bellows, the bellows in this specification are all taken as metal bellows as an example; the first bellows 2 is connected to the elastic sheet 3 through a pressure-sensing component 5 to make the elastic sheet 3 tilt; the movement amplification mechanism 4 is connected to the elastic sheet 3; during operation, the differential pressure between the high pressure and the low pressure drives one end of the elastic sheet 3 to warp and displace, and the displacement of the elastic sheet 3 further pushes the movement amplification mechanism 4 to display the differential pressure on the dial through a pointer; the specific structures of the above-mentioned movement amplification mechanism 4, the dial, and the pointer (not shown in the figure) themselves and the specific connection method with the elastic sheet 3 are all prior art and will not be repeated here.

[0012] When in use, the high-pressure gas and the low-pressure gas are respectively transported to the closed chambers of the first bellows 2 and the measuring tube 1 through the high-pressure channel 101 and the low-pressure channel 102. Since the first bellows 2 is fixed in the measuring tube 1, the high pressure and low pressure inside and outside the first bellows 2 cancel each other out, and the first bellows 2 only bears the differential pressure between the high pressure and the low pressure; the differential pressure drives the first bellows 2 to extend upward, thereby tilting the elastic sheet 3 and finally displaying the differential pressure through the movement amplification mechanism 4; it can be seen that by adopting the above scheme, when a first bellows 2 with a larger diameter is selected, the pressure-sensing area of ​​the first bellows 2 is increased to ensure the sensitivity of the device, and the bearing pressure of the first bellows 2 is reduced, thereby achieving a balance between sensitivity and pressure-bearing capacity.

[0013] like Figure 1 As shown, the present invention proposes another embodiment, one end of the elastic sheet 3 is fixedly mounted on the measuring tube 1, the top end of the first bellows 2 is open and the bottom end thereof is sealed and welded to the measuring tube 1; in order to facilitate the high-pressure channel 101 to be connected with the inner cavity of the first bellows 2, the bottom end of the first bellows 2 can also be set to be open and the high-pressure channel 101 is connected from below to the bottom end of the first bellows 2; the pressure-sensing component 5 includes a pressure-sensing plate 501 and a connecting rod 502 fixedly mounted on the pressure-sensing plate 501. In this embodiment, the pressure-sensing plate 501 is made of metal, and the pressure-sensing plate 501 is sealed and welded to the open end of the first bellows 2; both high pressure and low pressure act on the pressure-sensing plate 501. On the pressure plate 501, in practice, it is more convenient to calculate the pressure-sensitive area of ​​the pressure-sensitive plate 501 than to calculate the pressure-sensitive area of ​​the first bellows 2, which reduces the workload; the first bellows 2 and the connecting rod 502 are both set to be coaxial with the measuring tube 1 to ensure good symmetry and force; the free end of the connecting rod 502 passes through the air passage of one of the end covers 103 and abuts against the middle part of the elastic sheet 3, and the air passage restricts the connecting rod 502 from swinging at will, and the connecting rod 502 further plays a vertical guiding role for the pressure-sensitive plate 501 and the first bellows 2. It should be understood that if the above scheme is adopted, a conventional dynamic sealing structure needs to be set between the connecting rod 502 and the measuring tube 1 to ensure that the inner cavity of the measuring tube 1 is closed.

[0014] Furthermore, it also includes a second bellows 6 sleeved on the outside of the connecting rod 502, the second bellows 6 is coaxial with the first bellows 2, and the two ends of the second bellows 6 are respectively sealed and welded to the measuring tube 1 and the pressure-sensitive plate 501 to close the inner cavity of the measuring tube 1. Since the second bellows 6 realizes the sealing of the inner cavity of the measuring tube 1, the adoption of this technical solution does not require the provision of a dynamic sealing structure between the connecting rod 502 and the measuring tube 1; in addition, the second bellows 6 enhances the guiding effect on the first bellows 2, so that the first bellows 2 and the second bellows 6 only produce vertical movement when subjected to force to avoid deflection; the inner cavity of the second bellows 6 is facing one of the airways and the two are connected. During the compression process of the second bellows 6, the second bellows 6 discharges the gas in the inner cavity to the outside to avoid affecting the detection result.

[0015] Furthermore, it also includes a third bellows 7 sleeved in the first bellows 2, the third bellows 7 is coaxial with the first bellows 2, and both ends of the third bellows 7 are respectively sealed and welded on the measuring tube 1 and the pressure-sensitive plate 501. Similarly, the third bellows 7 further enhances the guiding effect on the first bellows 2, so that each bellows only produces vertical movement when subjected to force; in order to prevent the gas in the inner cavity of the third bellows 7 from affecting the detection result, the inner cavity of the third bellows 7 is connected to another airway.

[0016] like Figure 1 As shown, the present invention proposes another embodiment, the diameters of the second bellows 6 and the third bellows 7 are smaller than the first bellows 2, and the second bellows 6 and the third bellows 7 with smaller diameters can withstand greater pressure than the first bellows 2. In this embodiment, the diameters of the second bellows 6 and the third bellows 7 are equal; of course, the diameters of the second bellows 6 and the third bellows 7 can also be set to be unequal, for example, the diameter of the third bellows 7 is set to be larger than the diameter of the second bellows 6, so that the third bellows 7 can withstand the high pressure in the inner cavity of the first bellows 2.

[0017] like Figure 1 As shown, the present invention proposes another embodiment, the pressure-sensitive plate 501 includes a cylindrical body and a flange fixed on the ring side of the body, the flange is sealed and welded to the end face of the first bellows 2, the body is coaxial with the first bellows 2 and its insertion into the first bellows 2 reduces the axial size of the device and provides an installation space for the second bellows 6, the initial lengths of the second bellows 6 and the third bellows 7 are equal, and their opposite ends are respectively sealed and fixed on both sides of the body; the diameter and initial length of the second bellows 6 and the third bellows 7 are equal, which further improves the symmetry of the differential pressure gauge, and each bellows is subjected to more uniform force and can only move vertically, and is durable.

[0018] like Figure 1 As shown, further, the main body is fitted with the inner wall of the first bellows 2, and the main body is supported inside the first bellows 2 to further prevent the first bellows 2 from swinging.

[0019] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A differential pressure gauge, characterized in that: The invention comprises a measuring tube (1) having a sealed cavity, a first bellows (2) fixed in the cavity of the measuring tube (1), an elastic sheet (3) and a movement amplifying mechanism (4) installed outside the measuring tube (1), wherein the measuring tube (1) is provided with a high-pressure channel (101) connected to the inner cavity of the first bellows (2) and a low-pressure channel (102) connected to the inner cavity of the measuring tube (1), the first bellows (2) having a sealed inner cavity, the first bellows (2) being connected to the elastic sheet (3) via a pressure sensing component (5) so that the elastic sheet (3) is tilted, and the movement amplifying mechanism (4) is connected to the elastic sheet (3) to display differential pressure; One end of the elastic sheet (3) is fixed on the measuring tube (1); one end of the first bellows (2) is open and the other end is sealed and fixed on the measuring tube (1); the pressure-sensing component (5) comprises a pressure-sensing plate (501) and a connecting rod (502) fixed on the pressure-sensing plate (501); the pressure-sensing plate (501) is sealed and fixed on the open end of the first bellows (2); the free end of the connecting rod (502) passes through the measuring tube (1) and abuts against the elastic sheet (3); It also includes a second bellows (6) sleeved outside the connecting rod (502), the two ends of the second bellows (6) are respectively sealed and fixed on the measuring tube (1) and the pressure-sensitive plate (501), and the inner cavity of the second bellows (6) is connected to the outside; It also includes a third bellows (7) sleeved inside the first bellows (2), the two ends of the third bellows (7) being respectively sealed and fixed on the measuring tube (1) and the pressure-sensitive plate (501), and the inner cavity of the third bellows (7) being connected to the outside; The diameters of the second bellows (6) and the third bellows (7) are both smaller than the diameters of the first bellows (2); The pressure-sensitive plate (501) comprises a cylindrical body and a flange fixed on the ring side of the body, the body is inserted into the first bellows (2), the flange is sealed and fixed on the end surface of the first bellows (2), the second bellows (6) and the third bellows (7) have the same initial length and their opposite ends are sealed and fixed on both sides of the body respectively; The body is in contact with the inner wall of the first corrugated tube (2); The measuring cylinder (1) comprises an end cover (103), a cylinder body (105) with both ends open, and two pressure-sensing seats (104) detachably connected to the two ends of the cylinder body (105). The number of the end covers (103) is two and they are detachably connected to each of the pressure-sensing seats (104). Each of the end covers (103) is provided with an air passage connected to the outside, and each of the air passages is connected to the inner cavity of the second bellows (6) and the third bellows (7), respectively. The connecting rod (502) is coaxial with one of the air passages.

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