Pressure measuring assembly

Abstract

The utility model discloses a pressure measurement assembly and a manufacturing method, which can measure absolute pressure through a metal diaphragm and simplify the structure and process of the pressure measurement assembly. The pressure measuring assembly comprises a metal elastic body, the metal elastic body comprises a diaphragm extending transversely and a circle of base part which is integrally connected to the edge of the diaphragm and extends towards the back side, and the base part and the back side of the diaphragm define a pressure cavity which is used for containing a pressure medium to be measured and provided with an opening; the insulating layer is arranged on the surface of the forward side of the metal elastomer; the cover covers the central part of the diaphragm from the forward side, is connected to the forward side of the diaphragm through a circle of insulating connecting material, and forms a reference pressure cavity with the diaphragm; the pressure measuring circuit is arranged on the surface of the insulating layer and located in the reference pressure cavity; and the plurality of bonding pads are arranged on the surface of the insulating layer, are positioned outside the reference pressure cavity and are connected to a pressure measuring circuit through a plurality of electric lead-out parts arranged on the surface of the insulating layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a pressure measurement assembly. BACKGROUND

[0002] Currently, mainstream piezoresistive pressure sensors are usually coupled by a side of a diaphragm to a pressure medium to be measured, so as to generate corresponding strain, and the strain is converted into an electrical signal by a bridge composed of pressure-sensitive resistors on the side of the diaphragm. When the other side is coupled to atmospheric pressure, the pressure measured is a relative pressure (gauge pressure) with atmospheric pressure as the reference pressure. These diaphragms can be semiconductor diaphragms or metal diaphragms. For semiconductor diaphragms, a vacuum cover can be provided on the other side surface by micro-machining, so as to measure the pressure of the pressure to be measured relative to vacuum (absolute pressure). However, for metal diaphragms, although atmospheric pressure can be ignored in general cases because the metal diaphragm can be integrally machined and installed by welding, so that the measurable pressure can be as high as tens of megapascals, if the medium pressure to be measured is not too high relative to atmospheric pressure, the atmospheric pressure cannot be ignored at this time. If the absolute pressure is measured by a metal diaphragm, a metal cover can only be welded on the other side surface of the metal diaphragm, and the absolute pressure is measured by vacuumizing the inside of the metal cover.

[0003] CN112857635A discloses a metal diaphragm type pressure core, which is provided with a medium layer, a conductive layer and a thick film pressure sensitive resistance constituting a pressure measurement circuit on the surface of a metal elastic body to measure the pressure of a medium to be measured. If a metal cover is welded on the surface of the metal diaphragm, there are great difficulties, which are specifically shown as follows: when the metal cover is welded to the other side surface of the metal diaphragm, it is difficult to reliably insulate between the metal cover and the metal elastic body, and between the metal cover and the conductive layer, and if the electrical signal is led out from the via hole provided on the metal cover through a long flexible electrical connecting piece (even if the inside end of the connecting piece is welded to the welding pad before the metal cover is welded to the metal diaphragm), the process is also complex and still needs complex insulation and sealing treatment between the lead wire and the metal cover. In addition, if welding is performed in a vacuum environment so that the reference pressure cavity is vacuumized, such welding process requires high requirements and has high cost. UTILITY MODEL CONTENT

[0004] In view of the deficiencies of the prior art, the present application provides a pressure measurement assembly to solve at least one aspect of the above technical defects.

[0005] To achieve the above object, the present application provides the following technical scheme: a pressure measurement assembly, comprising:

[0006] A metal elastic body comprising a diaphragm extending in a transverse direction and a base integrally connected to an edge of the diaphragm and extending from the edge toward a back side to form a ring, the base and the back side of the diaphragm enclosing a pressure cavity for accommodating a pressure medium to be measured and having an opening;

[0007] An insulating layer provided on a front side surface of the metal elastic body;

[0008] A cover covering a central portion of the diaphragm from the front side, the cover being connected to the front side of the diaphragm by a ring of insulating connecting material and enclosing a reference pressure cavity with the diaphragm;

[0009] A pressure measurement circuit provided on a surface of the insulating layer and inside the reference pressure cavity;

[0010] And a plurality of pads provided on the surface of the insulating layer and outside the reference pressure cavity, the pads being connected to the pressure measurement circuit by a plurality of electrical leads provided on the surface of the insulating layer.

[0011] Preferably, the pressure measurement circuit comprises a plurality of piezoresistors and electrical connections configured to form a Wheatstone bridge with the piezoresistors.

[0012] Preferably, the piezoresistors are thick-film piezoresistors sintered to the front side surface of the insulating layer.

[0013] Preferably, the cover is a ceramic or glass article.

[0014] Preferably, the insulating layer is a first vitreous material sintered to the front side surface of the diaphragm.

[0015] Preferably, the insulating connecting material is a sintered second vitreous material, the cover being sealed and fixed to the front side of the insulating layer and the electrical leads by the sintered second vitreous material.

[0016] Preferably, the base is provided with an exhaust passage having one end communicating with the reference pressure cavity and the other end communicating with an outer wall of the base, the outer end of the exhaust passage being sealed by a seal.

[0017] Preferably, the exhaust passage comprises a transverse passage and a longitudinal passage in communication, the end of the transverse passage away from the longitudinal passage being in communication with the reference pressure cavity via the front side surface of the metal elastic body, the end of the longitudinal passage away from the transverse passage extending to the outer wall of the base and being sealed by a seal.

[0018] Preferably, the exhaust passage has one end in communication with the reference pressure cavity via the front side surface of the metal elastic body and the other end extending to the back side surface of the base and being sealed by a seal.

[0019] Preferably, the insulating connecting material also covers at least a portion of the pressure measuring circuit and or at least a portion of the electric lead-out portion located within the reference pressure chamber. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Longitudinal sectional view of the pressure measuring assembly of the first embodiment;

[0021] Figure 2 Top view of the partial structure of the pressure measuring assembly of the first embodiment;

[0022] Figure 3 Enlarged view of the portion A shown in Figure 1

[0023] Figure 4 Perspective view of the pressure measuring assembly of the second embodiment;

[0024] Figure 5 Sectional view of the pressure measuring assembly of the second embodiment along Figure 4 B-B shown;

[0025] Figure 6 Top view of the partial structure of the pressure measuring assembly of the second embodiment;

[0026] Figure 7 Perspective view of the partial structure of the pressure measuring assembly of the second embodiment;

[0027] BRIEF DESCRIPTION OF REFERENCE NUMERALS: 100, pressure sensor; 110, pressure chamber; 11, diaphragm; 12, base; 13, connecting portion; 14, insulating layer; 151, electric connecting portion; 152, electric lead-out portion; 153, pad; 15a, piezoresistor; 15b, piezoresistor; 15, pressure measuring circuit; 16, positioning groove; 17a, transverse passage; 17b, longitudinal passage; 17c, inner side one end; 17d, outer side one end; 17, exhaust passage; 1, metal elastic body; 20, reference pressure chamber; 22, longitudinal extension; 2, cover; 3, insulating connecting material; 4, external connecting lead wire; 5, sealing body; 141, first portion; 142, second portion; 21, transverse extension; 22, longitudinal extension; 23, flat portion. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. The following examples are exemplary and are used only to explain the present application, and cannot be interpreted as a limitation on the present application. In the following description, the same reference signs are used to represent the same or equivalent elements, and repeated descriptions are omitted.

[0029] ​In the description of this application, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of this application are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0030] In addition, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0031] It should be further understood that the term “and / or” used in this specification and the corresponding claims refers to any and all possible combinations of one or more of the listed items.

[0032] See also Figure 1 、 Figure 2 . In the first embodiment of the present invention, the pressure measuring assembly includes a metal elastic body 1. The metal elastic body 1 includes a transversely extending diaphragm 11 and a circle of base 12 integrally connected to the edge of the diaphragm 11 and extending toward the back side. The base 12 and the back side of the diaphragm 11 form a pressure chamber 110 for accommodating the pressure medium to be measured and having an opening. Among them, the front of the base 12 and the front of the diaphragm 11 are preferably located on the same transverse plane, and it has a greater thickness in the longitudinal direction than the diaphragm 11, so that it has greater rigidity relative to the diaphragm 11, so that when the diaphragm 11 is subjected to the medium pressure from the back side, the strain on the front of the base 12 can be ignored relative to the strain on the front of the diaphragm 11. Among them, the radially inner part of the back end of the base 12 can continue to extend downward to form a connecting portion 13 connected to an external element.

[0033] The metal elastic body 1 has a circular insulating layer 14 on the front side surface, and the insulating layer 14 has a pressure measuring circuit 15 on the surface. The pressure measuring circuit 15 can include two piezoresistors 15a and two piezoresistors 15b and an electrical connection part 151, and the four piezoresistors are configured as a Wheatstone bridge in a full-bridge form by the electrical connection part 151, in which two piezoresistors 15a are located in a low strain area, and the other two piezoresistors 15b are located in a high strain area (closer to the center of the diaphragm 11 than the low strain area). In this way, when the pressure medium in the pressure cavity 110 exerts a certain pressure on the diaphragm, the Wheatstone full-bridge outputs a corresponding electrical signal under the driving of the power supply, for example, the Wheatstone full-bridge is electrically connected to the outside through four electrical lead-out parts 152 (the number is related to the structure of the pressure measuring circuit) provided on the surface of the insulating layer 14, two of which are connected to the two ends of the power supply, and the other two output electrical signals. In other schemes, the pressure measuring circuit 15 can also be any other suitable structure, for example, it can include two Wheatstone half-bridges combined together, and the two piezoresistors 15a can also not be provided on the front side of the metal elastic body 1 but on other elements so that their resistance changes to zero. The above-mentioned piezoresistors can be thick film piezoresistors, metal strain gauges or silicon strain gauges, etc., and in this embodiment, the piezoresistors are preferably thick film piezoresistors which can be sintered on the front side surface of the insulating layer 14.

[0034] The pressure measuring assembly of the present embodiment also includes a cover 2. The cover 2 covers the center part of the diaphragm 11 from the front side, and is connected to the front side of the diaphragm 11 by a ring of insulating connecting material 3 (see Figure 3 ) and forms a reference pressure cavity 20 with the diaphragm 11. The pressure measuring circuit 15 is provided inside the reference pressure cavity 20, so as to avoid contact with the external environment. The pressure measuring assembly also includes a plurality of solder pads 153 provided on the surface of the insulating layer 14. These solder pads 153 are located outside the reference pressure cavity 20, and are connected to the pressure measuring circuit 15 inside the reference pressure cavity 20 through the electrical lead-out parts 152, which can be connected to external equipment through external connecting leads 4.

[0035] The cover 2 can include a lateral extension 21 and a longitudinal extension 22 extending from the edge of the lateral extension 21 to the side of the metal elastic body 1, wherein the lateral extension 21 can be circular and the longitudinal extension 22 can be annular. The bottom of the longitudinal extension 22 is fixed to the annular area (not labeled) of the insulating layer 14 and the positive side of the electric lead-out part 152 by the sintered second glass material, which annular area spans the inside and outside of the reference pressure cavity 20 from the electric lead-out part 152. The insulating layer 14 is the first glass material, such as glass or glaze, sintered to the positive side surface of the metal elastic body 1, and can also be organic or ceramic under the conditions allowed by the process. The insulating connecting material 3 is preferably the sintered second glass material, such as glass or glaze, and can also be glue with insulating properties in some other solutions. The insulating connecting material 3 can cover at least a part of the pressure measuring circuit 15 and / or the part of the electric lead-out part 152 inside the reference pressure cavity 20 in addition to the above-mentioned annular area, thereby forming a certain protection for the above-mentioned parts of the pressure measuring circuit 15 and / or the electric lead-out part 152. In this embodiment, the insulating connecting material 3 can cover the above-mentioned annular area and its inside to form a complete circular area S1.

[0036] The cover 2 can be metal, but is preferably ceramic or glass in this embodiment, so that the cover 2 can be better combined with the second glass material.

[0037] Preferably, the base 12 is provided with an exhaust passage 17 having one end communicating with the reference pressure cavity 20 and the other end communicating with the outer wall of the base 12. The outer end 17d of the exhaust passage 17 is sealed by a sealing body 5. More preferably, at least one longitudinal positioning groove 16 can be formed on the outer wall of the base 12 to form circumferential positioning with external elements or external devices. The outer end 17d of the exhaust passage 17 can be arranged at the bottom of the positioning groove 16 and sealed by a sealing body 5. The above-mentioned sealing body can be a steel ball, which can be fixed and sealed to the base 12 by welding. The exhaust passage 17 can include a communicating lateral passage 17a and a longitudinal passage 17b. The end of the longitudinal passage 17b away from the lateral passage 17a extends to the positive side and communicates with the reference pressure cavity 20. The end of the lateral passage 17a away from the longitudinal passage 17b extends laterally to the outer wall of the base 12. In particular, at least one longitudinal positioning groove 16 for positioning with external elements is arranged on the outer wall of the base 12. The outer end 17d of the exhaust passage 17 penetrates into the positioning groove 16 and is sealed by a sealing body 5.

[0038] The pressure measuring assembly of this embodiment can be obtained by the following manufacturing method:

[0039] A metal elastic body 1 is provided, which comprises a diaphragm 11 extending in a transverse direction, a base 12 integrally connected to the edge of the diaphragm 11 and extending towards a back side to form a ring, and a pressure cavity 110 formed by the back side of the diaphragm 11 and the base 12 and having an opening for accommodating a pressure medium to be measured;

[0040] An insulating layer 14 is formed on the front side surface of the metal elastic body 1 by coating a first glass paste, drying and sintering the first glass paste;

[0041] An electrically conductive layer is formed on the surface of the insulating layer 14 by coating an electrically conductive paste, drying and sintering the electrically conductive paste. The electrically conductive layer comprises an electrically connecting part 151, a plurality of electrically leading parts 152 and a plurality of pads 153;

[0042] A plurality of thick film pressure sensitive resistors are formed on the surface of the insulating layer 14 by coating a thick film pressure sensitive resistor paste, drying and sintering. The thick film pressure sensitive resistors are connected to the electrically connecting part 151 to form a pressure measuring circuit for measuring the pressure of the pressure medium in the pressure cavity 110. The pads 153 are electrically connected to the pressure measuring circuit through the electrically leading parts 152;

[0043] A layer of glass paste is arranged on at least one ring-shaped area on the insulating layer 14 which spans the electrically leading parts 152;

[0044] A ceramic cover 2 is positioned on the front side to cover the pressure measuring circuit so that a ring-shaped connecting plane on the back end of the cover 2 which is matched in shape and size with the ring-shaped area is in contact with the glass paste. The glass paste is then sintered to seal the cover 2 to the ring-shaped area by a second glass material so that the cover 2 and the metal elastic body 1 form a reference pressure cavity 20;

[0045] Preferably, the base 12 is further provided with an exhaust passage 17 which is connected to the reference pressure cavity 20 at one end and to the outer wall or the bottom wall of the base 12 at the other end. Correspondingly, the method for manufacturing the pressure measuring assembly further comprises: after the pressure in the reference pressure cavity 20 is set to a preset pressure, sealing a sealing body 5 to the outer end 17d of the exhaust passage 17. When the pressure in the reference pressure cavity 20 is set to the preset pressure, a protective gas such as nitrogen can be filled into the pressure cavity 110.

[0046] Please refer to Figure 4 to Figure 7 Compared with the first embodiment, the pressure measuring assembly of the second embodiment of the utility model can be changed as follows:

[0047] Unlike the longitudinal extension 22 in the first embodiment which is annular, the longitudinal extension 22 in the present embodiment has a flat portion 23 which is disposed across the front side of the electrical lead-out portion 152, so that the solder pad 153 has a larger space for arrangement, and the solder pad 153 can be arranged side by side to facilitate connection with external devices. Accordingly, the insulating connecting material 3 does not cover the annular region S1, but covers a region S2 which is composed of an arcuate strip-shaped region S21 and a straight strip-shaped region S22.

[0048] Unlike the outer end 17d of the exhaust passage 17 in the first embodiment which is disposed on the outer wall of the base 12, the outer end 17d of the exhaust passage 17 in the present embodiment extends directly longitudinally to the back surface of the base 12, and the back surface of the base 12 is easily disposed as a flat surface, so that the mounting of the sealing body 5 is more convenient.

[0049] In addition, in the present embodiment, the insulating layer 14 can include a first portion 141 which is generally annular and disposed on the back side of the pressure measurement circuit 15 and the electrical lead-out portion 152, and a second portion 142 which is disposed on the back side of S2. The insulating layer 14 does not cover the inner end 17c of the exhaust passage 17.

[0050] Similarly, the insulating connecting material 3 in the present embodiment, in addition to covering the region S2, can additionally cover at least a portion of the pressure measurement circuit 15 and / or the electrical lead-out portion 152 which is located in the reference pressure chamber 20, so that when the connecting cover 2 is connected to 1 through the insulating connecting material 3, the portion in the reference pressure chamber 20 can be protected at the same time. More directly, it can cover all other portions except the edge of the insulating layer 14.

[0051] The scope of the disclosure is not limited by the detailed description, but is instead defined by the claims, with equivalents of the claims to be within their scope. By the claims and their equivalents, all variations and modifications are intended to be included.

Claims

1. A pressure measuring assembly, characterized by The pressure sensor comprises: a metal elastic body (1) comprising a diaphragm (11) extending in a transverse direction and a base (12) integrally connected to the edge of the diaphragm (11) and extending towards the back side to form a ring, the base (12) and the back side of the diaphragm (11) forming a pressure cavity (110) for accommodating a pressure medium to be measured and having an opening; an insulating layer (14) provided on the front side surface of the metal elastic body (1); a cover (2) covering the central portion of the diaphragm (11) from the front side, which is connected to the front side of the diaphragm (11) by a ring of insulating connecting material (3) and forms a reference pressure cavity (20) with the diaphragm (11); a pressure measurement circuit (15) provided on the surface of the insulating layer (14) and located inside the reference pressure cavity (20); and a plurality of pads (153) provided on the surface of the insulating layer (14) and located outside the reference pressure cavity (20), which are connected to the pressure measurement circuit (15) through a plurality of electrical lead-out portions (152) provided on the surface of the insulating layer (14).

2. The pressure measurement assembly of claim 1, wherein, The pressure measurement circuit (15) comprises a plurality of piezoresistors (15a, 15b) and an electrical connection portion (151) configured as a Wheatstone bridge.

3. The pressure measurement assembly of claim 2, wherein, The piezoresistors (15a, 15b) are thick film piezoresistors sintered on the front side surface of the insulating layer (14).

4. The pressure measurement assembly of claim 1, wherein, The cover (2) is made of ceramic or glass.

5. The pressure measuring assembly according to any one of claims 1 to 4, characterized in that, The insulating layer (14) is a first glass material sintered on the front side surface of the diaphragm (11).

6. The pressure measurement assembly of claim 5, wherein, The insulating connecting material (3) is a sintered second glass material, and the cover (2) is sealed and fixed to the front side of the insulating layer (14) and the electrical lead-out portion (152) by the sintered second glass material.

7. The pressure measurement assembly of claim 1, wherein, The base (12) is provided with an exhaust passage (17) having one end connected to the reference pressure cavity (20) and the other end connected to the outer wall of the base (12), and the outer side end of the exhaust passage (17) is sealed by a sealing body (5).

8. The pressure measurement assembly of claim 7, wherein, The exhaust passage (17) comprises a transverse passage (17a) and a longitudinal passage (17b) connected in series, the end of the transverse passage (17a) away from the longitudinal passage (17b) is connected to the reference pressure cavity (20) through the front side surface of the metal elastic body (1); the end of the longitudinal passage (17b) away from the transverse passage (17a) extends to the outer wall of the base (12) and is sealed by a sealing body (5).

9. The pressure measurement assembly of claim 7, wherein, The exhaust passage (17) is connected to the reference pressure cavity (20) through the front side surface of the metal elastic body (1) at one end and extends to the back side surface of the base (12) at the other end, and is sealed by a sealing body (5).

10. The pressure measurement assembly of claim 1, wherein, The insulating connecting material (3) also covers at least a portion of the pressure measurement circuit and / or at least a portion of the electrical lead-out portion (152) located inside the reference pressure cavity (20).

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