A differential pressure flow meter and its sensing components
By employing a metal encapsulation shell and adhesive guide groove structure in the differential pressure flow meter, complementary wafers are encapsulated within the same isothermal body, solving the zero-point offset problem caused by temperature and humidity changes and achieving higher measurement accuracy and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN WEILANG INSTR CO LTD
- Filing Date
- 2025-08-27
- Publication Date
- 2026-06-30
AI Technical Summary
Traditional differential pressure flowmeters suffer from significant zero-point offset errors due to poor temperature uniformity of complementary wafers when temperature and humidity change, and existing technical solutions have failed to effectively address this issue.
Two complementary wafers are encapsulated in the same housing using a metal encapsulation shell, and a ceramic plate is fixed by adhesive channels and glue. This ensures that the wafers operate in the same isothermal body. The high thermal conductivity of the metal reduces temperature differences, and the adhesive in the adhesive channels absorbs thermal stress to prevent the ceramic plate from cracking.
It effectively offsets the zero-point offset caused by temperature and humidity changes, improves measurement accuracy, reduces the impact of heat generation, avoids the cracking of the ceramic plate, and ensures the reliability and accuracy of the sensing components.
Smart Images
Figure CN224435488U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of measurement technology, specifically to a differential pressure flow meter and its sensing components. Background Technology
[0002] Traditional differential pressure flowmeters typically use a single micro differential pressure wafer to measure the required signal. However, a single micro differential pressure wafer can experience zero-point shift when the temperature and humidity of the measurement environment change, leading to errors. To address this issue, related technologies, such as US Patent 6023978A, provide a solution using complementary outputs from dual micro differential pressure sensors. This solution connects the high-pressure end of a first wafer to the low-pressure end of a second wafer in the gas path, and simultaneously connects the low-pressure end of the first wafer to the high-pressure end of the second wafer. In the circuit, the positive output of the first wafer is connected to the negative output of the second wafer, and vice versa. When temperature and humidity change, the common-mode offset outputs of the first and second wafers are canceled out, thus suppressing zero-point shift caused by temperature and humidity changes. However, because the first and second wafers are encapsulated in different housings using engineering plastics, the temperature uniformity between the two complementary wafers is not optimized, resulting in a temperature difference between them, which affects the effectiveness of canceling zero-point shift when temperature and humidity change. Utility Model Content
[0003] In order to overcome the shortcomings of the prior art, the purpose of this utility model is to provide a sensing component that can optimize the temperature uniformity between two complementary wafers as much as possible and improve the effect of offsetting zero-point offset between the two complementary wafers.
[0004] To solve the above problems, the technical solution adopted by this utility model is as follows: A sensing component includes a metal encapsulation shell, a ceramic plate, a first wafer, and a second wafer, wherein the first wafer and the second wafer are bonded to the ceramic plate; the metal encapsulation shell includes a front cover and a rear cover, wherein the front cover has a low-voltage wafer slot and a high-voltage wafer slot, the ceramic plate, the first wafer, and the second wafer are encapsulated between the front cover and the rear cover, and the first wafer and the second wafer are respectively housed in the low-voltage wafer slot and the high-voltage wafer slot; both the inner sides of the front cover and the rear cover have adhesive guide grooves, and the adhesive guide grooves are filled with adhesive to fix the ceramic plate between the front cover and the rear cover.
[0005] Compared to existing technologies, the advantages of this invention are as follows: This sensing component places the low-voltage wafer slot and the high-voltage wafer slot on the same metal front cover, allowing the first and second wafers to be encapsulated within the same metal package. The metal package has a high thermal conductivity, reducing the heat generated during circuit board operation. This allows the two complementary wafers to operate within an isothermal environment, ensuring that the temperature changes are consistent across the two complementary wafers with virtually no temperature difference, thus better offsetting zero-point shifts. Due to the significant difference in thermal expansion coefficients between the metal package and the ceramic plate, to prevent thermal stress during thermal cycling from causing the ceramic plate to crack, this sensing component has adhesive guide grooves on the inner sides of both the front and rear covers, filled with adhesive to fix the ceramic plate between them. The adhesive in the guide grooves has a certain elasticity, absorbing sufficient thermal stress during temperature changes to prevent the ceramic plate from cracking.
[0006] In the aforementioned sensing component, the adhesive guide groove on the front cover is arranged around the outer periphery of the low-voltage wafer trench and the high-voltage wafer trench.
[0007] In the aforementioned sensing component, the bottom of the front cover is provided with a first low-voltage pressure tap and a first high-voltage pressure tap, which are respectively connected to the low-voltage wafer trench and the high-voltage wafer trench; the rear cover is provided with a low-voltage pressure trench and a high-voltage pressure trench; the ceramic plate is provided with a second low-voltage pressure tap and a second high-voltage pressure tap, which are connected to the low-voltage wafer trench and the low-voltage pressure trench, and the second high-voltage pressure tap is connected to the high-voltage wafer trench and the high-voltage pressure trench.
[0008] In the aforementioned sensing component, the adhesive guide groove on the rear cover is arranged around the outer periphery of the low-pressure guide groove and the high-pressure guide groove.
[0009] The aforementioned sensing component further includes a third wafer bonded to the ceramic plate, which is housed in either the low-voltage wafer trench or the high-voltage wafer trench. An atmospheric pressure-guiding hole is provided on the ceramic plate corresponding to the position of the third wafer, and an atmospheric communication hole communicating with the atmospheric pressure-guiding hole is provided on the rear cover.
[0010] The aforementioned sensing component has a metal encapsulation shell made of stainless steel, aluminum alloy, or copper.
[0011] This utility model also provides a differential pressure flow meter, including the above-mentioned sensing components, which has at least all the beneficial effects that the above-mentioned sensing components can bring.
[0012] The differential pressure flow meter described above also includes a base, a top cover, a throttling element, and a PCB main board. The throttling element is disposed between the base and the top cover. The sensing component is electrically connected to the PCB main board, and both the sensing component and the PCB main board are connected to the top cover.
[0013] In the aforementioned differential pressure flow meter, the PCB main board is equipped with a TVS or a varistor, the PE terminal of the PCB main board is connected to the metal package shell, and the PE terminal of the PCB main board is connected to the reference ground of the PCB main board through the TVS or varistor.
[0014] The differential pressure flow meter described above has a fluid inlet and a fluid outlet on its base. The fluid inlet, the throttling element, and the fluid outlet are connected in sequence. The upper cover has a third low-pressure tap and a third high-pressure tap. The third low-pressure tap connects the throttling element to the first low-pressure tap, and the third high-pressure tap connects the throttling element to the first high-pressure tap.
[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the overall structure of the sensing component according to Embodiment 1 of this utility model;
[0017] Figure 2 for Figure 1 One of the exploded diagrams of the structure shown;
[0018] Figure 3 for Figure 1 The second exploded diagram of the structure shown, in which, Figure 2 and Figure 3 These are different perspectives of the exploded diagram;
[0019] Figure 4 This is a schematic diagram of the front cover of Embodiment 1 of the present invention;
[0020] Figure 5 This is a diagram showing the fit and relationship between the front cover, ceramic plate, first wafer, second wafer, and third wafer in Embodiment 1 of this utility model. Part of the ceramic plate has been cut off to make the positions of the first wafer, second wafer, and third wafer clear.
[0021] Figure 6 This is a schematic diagram of the overall structure of the differential pressure flow meter according to Embodiment 2 of this utility model;
[0022] Figure 7 for Figure 6 A cross-sectional view of the structure shown;
[0023] Figure 8 This is a partial circuit diagram of the differential pressure flowmeter according to Embodiment 2 of this utility model.
[0024] Explanation of icon numbers:
[0025] 100 Sensing component, 110 Metal package housing, 111 Front cover, 1111 Low-voltage wafer slot, 1112 High-voltage wafer slot, 1113 First low-voltage pressure port, 1114 First high-voltage pressure port, 112 Rear cover, 1121 Low-voltage pressure groove, 1122 High-voltage pressure groove, 1123 Atmosphere communication hole, 113 Adhesive guide groove, 120 Ceramic plate, 121 Second low-voltage pressure port, 122 Second high-voltage pressure port, 123 Atmosphere pressure port, 124 First pressure port, 125 Second pressure port, 130 First wafer, 140 Second wafer, 150 Third wafer;
[0026] 200 base, 210 fluid inlet, 220 fluid outlet;
[0027] 300 Top cover, 310 Third low-pressure tap, 320 Third high-pressure tap;
[0028] 400 throttling element;
[0029] 500PCB motherboard. Detailed Implementation
[0030] The embodiments of this utility model are described in detail below.
[0031] Example 1
[0032] Reference Figures 1 to 5 Embodiment 1 of this utility model provides a sensing component 100, including a metal encapsulation shell 110, a ceramic plate 120, a first wafer 130, and a second wafer 140. The first wafer 130 and the second wafer 140 are bonded to the ceramic plate 120 and then encapsulated together with the ceramic plate 120 within the metal encapsulation shell 110. The metal encapsulation shell 110 includes a front cover 111 and a rear cover 112. The rear cover 112 is locked and fixed to the front cover 111 by screws or other locking devices. The front cover 111 is locked to other structures of the differential pressure flow meter by screws or other locking devices.
[0033] Furthermore, referring to Figure 2 , Figure 4 and Figure 5The front cover 111 has a low-voltage wafer slot 1111 and a high-voltage wafer slot 1112. The ceramic plate 120, the first wafer 130, and the second wafer 140 are encapsulated between the front cover 111 and the rear cover 112, with the first wafer 130 and the second wafer 140 respectively housed in the low-voltage wafer slot 1111 and the high-voltage wafer slot 1112. The end of the first wafer 130 and the second wafer 140 facing the front cover 111 is the high-voltage end, and the end facing the rear cover 112 is the low-voltage end. The bottom of the front cover 111 is also provided with a first low-pressure tapping hole 1113 and a first high-pressure tapping hole 1114. The first low-pressure tapping hole 1113 and the first high-pressure tapping hole 1114 are respectively connected to the low-pressure end wafer trench 1111 and the high-pressure end wafer trench 1112. After the sensing component 100 is installed on the other structure of the differential pressure flow meter, during operation, the low-pressure end air pressure will enter the low-pressure end wafer trench 1111 from the first low-pressure tapping hole 1113 and act on the high-pressure end of the first wafer 130 in the low-pressure end wafer trench 1111. The high-pressure end air pressure will enter the high-pressure end wafer trench 1112 from the first high-pressure tapping hole 1114 and act on the high-pressure end of the second wafer 140 in the high-pressure end wafer trench 1112.
[0034] Furthermore, referring to Figure 2 and Figure 3 The rear cover 112 has a low-pressure tapping groove 1121 and a high-pressure tapping groove 1122. The ceramic plate 120 has a second low-pressure tapping hole 121 and a second high-pressure tapping hole 122. The second low-pressure tapping hole 121 connects the low-pressure end wafer trench 1111 and the low-pressure tapping groove 1121, and the second high-pressure tapping hole 122 connects the high-pressure end wafer trench 1112 and the high-pressure tapping groove 1122. The second low-pressure tapping hole 121 and the second high-pressure tapping hole 122 on the ceramic plate 120 introduce low-pressure and high-pressure gas into the rear cover 112. The low-pressure end of the first wafer 130 introduces high pressure through the high-pressure tapping groove 1122 on the rear cover 112, and the low-pressure end of the second wafer 140 introduces low pressure through the low-pressure tapping groove 1121 on the rear cover 112. Therefore, low-pressure gas is introduced into the high-pressure end of the first wafer 130 and the low-pressure end of the second wafer 140, and high-pressure gas is introduced into the low-pressure end of the first wafer 130 and the high-pressure end of the second wafer 140, thus realizing the reverse gas path connection between the first wafer 130 and the second wafer 140.
[0035] Furthermore, a third wafer 150 is also bonded to the ceramic plate 120. The third wafer 150 is used to measure pressure to convert the operating flow rate into the standard flow rate. It can be housed in the low-pressure wafer slot 1111, or in the high-pressure wafer slot 1112. Similarly, the end of the third wafer 150 facing the front cover 111 is the high-pressure end, and the end facing the rear cover 112 is the low-pressure end. An atmospheric pressure tap 123 is provided on the ceramic plate 120 corresponding to the position of the third wafer 150, and an atmospheric communication hole 1123 communicating with the atmospheric pressure tap 123 is provided on the rear cover 112. The first wafer 130 and the second wafer 140 are differential pressure wafers, and the third wafer 150 is an absolute pressure or gauge pressure wafer. Specifically, refer to... Figure 2 and Figure 3 The ceramic plate 120 has a first pressure-guiding hole 124 and a second pressure-guiding hole 125 at positions corresponding to the first wafer 130 and the second wafer 140. The front ends of the first pressure-guiding hole 124 and the second pressure-guiding hole 125 are respectively bonded to the first wafer 130 and the second wafer 140, and the rear ends are respectively connected to the high-voltage pressure-guiding groove 1122 and the low-voltage pressure-guiding groove 1121, so that the low-voltage end of the first wafer 130 can introduce high voltage through the high-voltage pressure-guiding groove 1122 on the back cover 112, and the low-voltage end of the second wafer 140 can introduce low voltage through the low-voltage pressure-guiding groove 1121 on the back cover 112.
[0036] This sensing component 100 places the low-voltage wafer bay 1111 and the high-voltage wafer bay 1112 on the same metal front cover 111, allowing the first wafer 130 and the second wafer 140 to be encapsulated within the same metal package 110. The metal package 110 has a high thermal conductivity, which reduces the heat generated during circuit board operation, enabling the two complementary wafers to operate in an isothermal environment. When the temperature changes, the temperature effects on the two complementary wafers are consistent, with almost no temperature difference, thus better canceling out zero-point offsets. Furthermore, the metal package 110 is made of stainless steel, aluminum alloy, or copper, preferably aluminum alloy, which has a higher thermal conductivity, better avoiding the heat generated during PCB motherboard 500 operation, achieving faster thermal equilibrium, and reducing processing costs.
[0037] The metal casing 110 of this sensing component 100 is a metal structural component. Due to the significant difference in thermal expansion coefficients between the metal casing 110 and the ceramic plate 120, to prevent thermal stress during thermal cycling from causing the ceramic plate 120 to crack, the sensing component 100 has adhesive guide grooves 113 on the inner sides of both the front cover 111 and the rear cover 112. Adhesive is filled into the adhesive guide grooves 113 to fix the ceramic plate 120 between the front cover 111 and the rear cover 112. The adhesive in the adhesive guide grooves 113 has a certain degree of elasticity, which can absorb sufficient thermal stress during temperature changes, thereby preventing the ceramic plate 120 from cracking. The adhesive guide grooves 113 ensure that after the adhesive cures, it not only fixes the ceramic plate 120 but also ensures that the adhesive thickness meets the requirements. Furthermore, the adhesive guide grooves 113 on the front cover 111 surround the outer periphery of the low-voltage wafer trench 1111 and the high-voltage wafer trench 1112. The adhesive guide groove 113 on the back cover 112 is arranged around the outer periphery of the low-pressure guide groove 1121 and the high-pressure guide groove 1122. The adhesive guide groove 113 can be set to an appropriate depth according to the thermal expansion coefficient of the adhesive, metal and ceramic.
[0038] Example 2
[0039] Reference Figure 6 and Figure 7 Embodiment 2 of this utility model provides a differential pressure flow meter, including the aforementioned sensing component 100, which has at least all the beneficial effects that the aforementioned sensing component 100 can bring.
[0040] Furthermore, the differential pressure flow meter also includes a base 200, a top cover 300, a throttling element 400, and a PCB main board 500. The throttling element 400 is located between the base 200 and the top cover 300. The top cover 300 can press the throttling element 400 onto the base 200, and a sealing gasket can be added if necessary. The sensing component 100 is electrically connected to the PCB main board 500, and both the sensing component 100 and the PCB main board 500 are connected to the top cover 300. In the circuit, the positive output of the first wafer 130 is connected to the negative output of the second wafer 140, and the negative output of the first wafer 130 is connected to the positive output of the second wafer 140, completing the wafer signal crossover in the circuit. Since the copper wires and each wafer are located on the same side in the circuit, the distance between the wires and the front cover 111 is relatively short. At this time, the pressure resistance level between the wires and the front cover 111 can be ensured by setting the thickness of the adhesive.
[0041] Furthermore, referring to Figure 8The PCB motherboard 500 is equipped with a TVS or varistor. The PE terminal of the PCB motherboard 500 is connected to the metal package housing 110, and the PE terminal of the PCB motherboard 500 is connected to the reference ground of the PCB motherboard 500 through the TVS or varistor. By setting the clamping voltage of the TVS or varistor and leaving sufficient margin, it can be ensured that the TVS or varistor conducts and releases energy before the adhesive layer of the sensing component 100 is broken down, so as to avoid electrostatic discharge breaking down the adhesive layer between the metal package housing 110 and the conductors on the ceramic plate 120, and avoid damage to the wafer inside the PCB motherboard 500 or the sensing component 100. Specifically, the PE terminal of the PCB motherboard 500 can be connected to the front cover 111 of the sensing component 100 via screws. Therefore, the PE terminal of the metal package 110 and the PCB motherboard 500 are at the same potential. The PE terminal of the PCB motherboard 500 is then connected to the reference ground GND of the PCB motherboard 500 via a TVS or varistor. After the sensing component 100 is soldered onto the PCB motherboard 500, the signal voltage on the ceramic plate 120 is a low voltage relative to GND. When static electricity or surge occurs, the potential difference between the wires on the metal package 110 and the ceramic plate 120 is controlled by the TVS or varistor. Therefore, by selecting a suitable TVS or varistor, it can be ensured that the adhesive layer will not be broken down, ensuring the safe and reliable operation of the sensing component 100.
[0042] Specifically, the base 200 has a fluid inlet 210 and a fluid outlet 220, which are sequentially connected. The upper cover 300 has a third low-pressure tap 310 and a third high-pressure tap 320. The third low-pressure tap 310 connects the throttling element 400 to the first low-pressure tap 1113, and the third high-pressure tap 320 connects the throttling element 400 to the first high-pressure tap 1114. When fluid flows from the fluid inlet 210 through the throttling element 400 and out of the fluid outlet 220, low-pressure gas can enter the first low-pressure tap 1113 from the third low-pressure tap 310, and high-pressure gas can enter the first high-pressure tap 1114 from the third high-pressure tap 320. Specifically, the throttling element 400 can be in the form of a laminar flow element, an orifice plate, or a sonic nozzle, etc., and is not limited here, as long as it can generate a pressure difference when the fluid flows through it.
[0043] It should be noted that in the description of this utility model, any descriptions of orientation, such as up, down, front, back, left, right, etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of this utility model.
[0044] In the description of this utility model, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first" or "second" is mentioned, it is only for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0045] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.
[0046] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.
Claims
1. A sensing assembly, characterized by, It includes a metal encapsulation shell (110), a ceramic plate (120), a first wafer (130) and a second wafer (140), wherein the first wafer (130) and the second wafer (140) are bonded to the ceramic plate (120); The metal encapsulation housing (110) includes a front cover (111) and a rear cover (112). The front cover (111) has a low-voltage wafer slot (1111) and a high-voltage wafer slot (1112). The ceramic plate (120), the first wafer (130) and the second wafer (140) are encapsulated between the front cover (111) and the rear cover (112), and the first wafer (130) and the second wafer (140) are respectively housed in the low-voltage wafer slot (1111) and the high-voltage wafer slot (1112). The inner sides of the front cover (111) and the rear cover (112) are provided with adhesive guide grooves (113), which are filled with adhesive to fix the ceramic plate (120) between the front cover (111) and the rear cover (112).
2. The sensing assembly of claim 1, wherein, The adhesive guide groove (113) on the front cover (111) is arranged around the outer periphery of the low-voltage wafer trench (1111) and the high-voltage wafer trench (1112).
3. The sensing assembly of claim 1, wherein, The bottom of the front cover (111) is provided with a first low-pressure tapping hole (1113) and a first high-pressure tapping hole (1114), and the first low-pressure tapping hole (1113) and the first high-pressure tapping hole (1114) are respectively connected to the low-pressure end wafer trench (1111) and the high-pressure end wafer trench (1112). The rear cover (112) is provided with a low-pressure tapping groove (1121) and a high-pressure tapping groove (1122). The ceramic plate (120) is provided with a second low-pressure tapping hole (121) and a second high-pressure tapping hole (122). The second low-pressure tapping hole (121) connects the low-pressure end wafer groove (1111) and the low-pressure tapping groove (1121), and the second high-pressure tapping hole (122) connects the high-pressure end wafer groove (1112) and the high-pressure tapping groove (1122).
4. The sensing component according to claim 3, characterized in that, The adhesive guide groove (113) on the back cover (112) is arranged around the outer periphery of the low pressure guide groove (1121) and the high pressure guide groove (1122).
5. The sensing component according to claim 3, characterized in that, A third wafer (150) is also bonded to the ceramic plate (120), and the third wafer (150) is housed in the low-voltage wafer trench (1111) or the high-voltage wafer trench (1112); An atmospheric pressure hole (123) is provided on the ceramic plate (120) at a position corresponding to the third wafer (150), and an atmospheric communication hole (1123) is provided on the back cover (112) that communicates with the atmospheric pressure hole (123).
6. The sensing component according to any one of claims 1-5, characterized in that, The metal encapsulation shell (110) is made of stainless steel, aluminum alloy or copper.
7. A differential pressure flow meter, characterized in that, Includes the sensing component (100) as described in any one of claims 1-6.
8. The differential pressure flow meter according to claim 7, characterized in that, It also includes a base (200), a top cover (300), a throttling element (400), and a PCB motherboard (500). The throttling element (400) is disposed between the base (200) and the top cover (300). The sensing component (100) is electrically connected to the PCB motherboard (500), and both the sensing component (100) and the PCB motherboard (500) are connected to the top cover (300).
9. The differential pressure flow meter according to claim 8, characterized in that, The PCB motherboard (500) is provided with a TVS or a varistor. The PE terminal of the PCB motherboard (500) is connected to the metal package shell (110), and the PE terminal of the PCB motherboard (500) is connected to the reference ground of the PCB motherboard (500) through the TVS or varistor.
10. The differential pressure flow meter according to claim 8, characterized in that, The base (200) has a fluid inlet (210) and a fluid outlet (220). The fluid inlet (210), the throttling element (400) and the fluid outlet (220) are connected in sequence. The top cover (300) has a third low-pressure tapping hole (310) and a third high-pressure tapping hole (320). The third low-pressure tapping hole (310) connects the throttling element (400) and the first low-pressure tapping hole (1113). The third high-pressure tapping hole (320) connects the throttling element (400) and the first high-pressure tapping hole (1114).