CN220772417U

CN220772417U - Differential pressure sensor

Info

Publication number: CN220772417U
Application number: CN202321115912.4U
Authority: CN
Inventors: 王小平; 曹万; 杨军; 王红明; 赵鹍; 洪鹏
Original assignee: Wuhan Finemems Inc
Current assignee: Wuhan Finemems Inc
Priority date: 2023-05-07
Filing date: 2023-05-07
Publication date: 2024-04-12
Anticipated expiration: 2033-05-07

Abstract

A differential pressure sensor, comprising: a housing defining a mounting cavity, including a housing, an upper cover and a lower cover; a pressure sensing assembly disposed within the mounting cavity; the pressure sensing assembly comprises a first circuit board, a second circuit board, a first surrounding frame and two pressure chips; a first pressure tube for introducing a first pressure into the first pressure chamber and a second pressure tube for introducing a second pressure into the second pressure chamber; the first enclosing frame, the first circuit board and the second circuit board enclose to form a first cavity, and the first enclosing frame and the second circuit board enclose to form two left and right spaced second cavities; the pressure chip is electrically connected with the second circuit board through a first electric connecting piece positioned in the second cavity, and the second circuit board is electrically connected with the first circuit board through a first electric connecting piece positioned in the first cavity; the first pressure cavity and the second pressure cavity are communicated to the two second cavities in a one-to-one correspondence manner; the first and second chambers are filled with a first protective gel that can increase the life of the pressure sensor.

Description

Differential pressure sensor

Technical Field

The application relates to the technical field of pressure sensors, in particular to a differential pressure sensor.

Background

Pressure sensors are sensors for measuring the pressure of an environment or medium, and MEMS (microelectromechanical systems) are currently widely used due to low cost and small volume, which measure the pressure by the piezoresistive effect of semiconductor silicon. The middle part of the silicon core body is provided with a film shape, the pressure applied to the silicon film on two sides changes the resistance value of the doped resistor on the silicon film, and a current or voltage signal output by a measuring circuit formed by connecting a plurality of resistors can be further processed by a conditioning circuit and then the measuring result is output. When a vacuum cavity is arranged on one side of the diaphragm in the silicon chip, the measured pressure is the pressure applied by the other side relative to the vacuum pressure, namely the absolute pressure; when atmospheric pressure is introduced into one side of the diaphragm, the measured pressure is the pressure relative to the atmosphere, namely gauge pressure; when other pressures are respectively introduced to the two sides of the diaphragm, the measured pressure is the difference between the pressures of the two sides, namely the differential pressure. The pressure core can be arranged on a ceramic matrix or a metal matrix with a special thermal expansion coefficient to avoid precision reduction and even stress damage caused by temperature expansion coefficient mismatch, and the conditioning circuit is arranged on a printed circuit board fixed with the matrix.

Under severe working conditions such as high temperature, vibration and the like, the pressure core of the pressure sensor is more easily damaged by temperature stress to fail when the temperature changes. For example, to meet the national six emission standards, diesel engines typically require an EGR (exhaust gas recirculation) loop, where the exhaust gas Gao Wenjiao typically has an exhaust gas temperature of 130 ℃ that is 30-40 ℃ higher; at this time, the life of the printed circuit board may be significantly reduced.

One of the applicant's assumptions is to mount the pressure core on a ceramic substrate or a metal substrate of a particular thermal expansion coefficient to reduce the risk of damage to temperature stresses, but due to cost and technical considerations, it is preferable that the ceramic or metal substrate is glued to the printed circuit board and the pressure core is fixed to the pads on the printed circuit board by Jin Sibang after the glue has cured. However, the two are not firmly fixed due to adhesion, so that the risk of breakage and desoldering of the gold wire caused by displacement and false touch occurs during production and assembly or use is caused; on the other hand, the tightness of the sensor is reduced at high temperature, so that the medium to be measured (such as high-temperature tail gas) is more likely to invade the cavity where the electronic element is located, and the service life of the sensor is further reduced.

The statements in this section merely provide background information related to the present application and may not constitute prior art.

Disclosure of Invention

In view of the shortcomings of the prior art, the application provides a differential pressure sensor, so that manufacturability of the differential pressure sensor can be improved on the premise of protecting a circuit.

In order to achieve the above purpose, the present application provides the following technical solutions: a differential pressure sensor, comprising:

a housing defining a mounting cavity, including a housing, an upper cover and a lower cover;

the pressure sensing assembly is arranged in the mounting cavity and divides the mounting cavity into an upper part and a lower part, and the lower part of the mounting cavity comprises a first pressure cavity and a second pressure cavity which are mutually isolated; the pressure sensing assembly comprises a first circuit board, a second circuit board, a first surrounding frame and two pressure chips, wherein the first circuit board is horizontally arranged, the second circuit board is adhered to the lower side surface of the first circuit board, the first surrounding frame is adhered to the lower side surface of the second circuit board, and the two pressure chips are arranged on the first surrounding frame;

a first pressure tube for introducing a first pressure into the first pressure chamber and a second pressure tube for introducing a second pressure into the second pressure chamber;

the first enclosing frame, the first circuit board and the second circuit board are enclosed together to form a first cavity, the first enclosing frame and the second circuit board are enclosed to form two left and right spaced second cavities, and the two pressure chips are arranged in the two second cavities in a one-to-one correspondence manner; the pressure chip is electrically connected with the second circuit board through a first electric connecting piece positioned in the second cavity, and the second circuit board is electrically connected with the first circuit board through a first electric connecting piece positioned in the first cavity; the first pressure cavity and the second pressure cavity are communicated to the two second cavities in a one-to-one correspondence manner; the first cavity and the second cavity are filled with first protective gel; one second cavity is positioned between the other second cavity and the first cavity, the front side wall and the rear side wall of the first enclosure frame, which correspond to the first cavity, respectively protrude towards the front side and the rear side to form side positioning parts, and the upper ends of the side positioning parts are abutted to the lower surface of the first circuit board.

Preferably, the first enclosure frame comprises a wall extending up and down and two partition boards integrally connected in the wall, and the partition boards divide a space enclosed between the first enclosure frame and the second circuit board into one first cavity and two second cavities.

Preferably, the first enclosure frame further comprises a plate fixed at the lower end of the wall, three windows corresponding to the first cavity and the two second cavities one by one are formed in the plate, and the two second cavities are communicated to the corresponding pressure cavities through the corresponding windows.

Preferably, the plate is fixedly supported downwards on a supporting surface formed on the shell; two through holes which are opposite to the two windows in a one-to-one correspondence manner are formed on the supporting surface.

Preferably, the periphery of the via hole is recessed inwards to form a circle of second sealing groove, the periphery of each window is downward to form a circle of sealing flange correspondingly inserted and extended in the second sealing groove, and the second sealing groove is internally provided with first sealing adhesive.

Preferably, the upper cover comprises a cover plate and a flange formed by downwards protruding the horizontal edge of the cover plate, the upper end edge of the shell correspondingly forms a circle of first sealing grooves, and the inner side and the outer side of each first sealing groove correspondingly form a circle of inner surrounding walls and a circle of outer surrounding walls; the flange is correspondingly inserted into the first sealing groove, and the second sealing adhesive is filled in the first sealing groove.

Preferably, the left end and the right end of the shell are fixedly connected with an electric connector, a plurality of first contact pins are fixedly arranged on the electric connector, the first ends of the first contact pins inwards extend into the upper part of the mounting cavity, the first ends are provided with fish-eye structures, and the fish-eye structures are upwards tightly matched in metallized connecting holes formed in the left end and the right end of the first circuit board.

Preferably, the metallized connection hole is disposed on a portion of one side edge of the first circuit board that is exposed toward an edge of the second circuit board.

Preferably, the upper surface of the first circuit board is provided with an electronic element, the periphery of the electronic element is provided with a second enclosing frame, and the second enclosing frame is filled with second protective gel.

According to the differential pressure sensor, the first enclosure frame, the first circuit board and the second circuit board are arranged to form the first cavity and the second cavities, so that the first electric connecting piece, the second electric connecting piece and the pressure chip can be protected respectively, and the service life of the pressure sensor can be prolonged.

Drawings

FIG. 1 is an exploded view of a differential pressure sensor according to a preferred embodiment of the present utility model;

FIG. 2 is a cross-sectional view (upper cover omitted) of a differential pressure sensor according to a preferred embodiment of the present utility model;

FIG. 3 is a perspective cross-sectional view (upper cover omitted) of a differential pressure sensor according to a preferred embodiment of the present utility model;

FIG. 4 is a perspective view of a pressure sensing assembly according to a preferred embodiment of the present utility model;

FIG. 5 is a top view of a pressure sensing assembly according to a preferred embodiment of the present utility model;

in the figure: 400. a differential pressure sensor; 402. a mounting part; 403. a bushing; 404. an electrical connector; 4051. a first pressure chamber; 4052. an inner cavity; 405. a first pressure tube; 4061. a second pressure chamber; 4062. an inner cavity; 406. a second pressure tube; 4071. a yielding slot; 4072. an inner peripheral wall; 4073. a peripheral wall; 407. a first seal groove; 4081. a first end; 4082. a second end; 4084. a fish-eye structure; 408. a contact pin; 4091. a via hole; 409. a support surface; 410. a housing; 411. a contact positioning portion; 413. a second seal groove; 420. a pressure sensing assembly; 4211. metallized connecting holes; 421. a first circuit board; 422. a second circuit board; 4231. a wall; 4232. a plate; 4233. a side positioning part; 4234. a partition plate; 4235. a sealing flange; 423. a first enclosure; 424. a pressure chip; 4251. a first electrical connection; 4252. a second electrical connection; 4271. a first chamber; 4272. a second chamber; 428. a window; 429. an electronic component; 430. an upper cover; 431. a cover plate; 432. a flange; 433. a protrusion; 434. steel balls; 435. reinforcing ribs; 436. fool-proof positioning part; 440. a lower cover;

Detailed Description

The technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings. The following examples are illustrative only and are not to be construed as limiting the present application. In the following description, the same reference numerals are used to designate the same or equivalent elements, and duplicate descriptions are omitted.

In the description of the present application, it should be understood that the azimuth or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. are based on the azimuth or positional relationship shown in the drawings, or the azimuth or positional relationship in which the product of the present application is conventionally put in use, or the azimuth or positional relationship as is conventionally understood by those skilled in the art, are merely for convenience of description of the present application and for simplification of description, and are not indicative or implying that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be construed as limiting the present application.

In addition, the terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application can be understood as appropriate by one of ordinary skill in the art.

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

As shown in fig. 1 to 5. In a preferred embodiment of the present utility model, the differential pressure sensor 400 includes a housing consisting of a case 410 and an upper cover 430 fastened downward to the case 410. The housing 410 and the upper cover 430 together define a mounting cavity (not labeled).

The pressure sensing component 420 is disposed in the mounting cavity and partitions the mounting cavity into an upper portion and a lower portion. The lower portion of the mounting chamber includes a first pressure chamber 4051 and a second pressure chamber 4061 that are isolated. The pressure sensing component 420 specifically includes a first circuit board 421 disposed horizontally, a second circuit board 422 adhered to a lower surface of the first circuit board 421, a first peripheral frame 423 adhered to a lower surface of the second circuit board 422, and two pressure chips 424. The pressure chip 424 may be an absolute pressure chip, wherein one side of a diaphragm of the absolute pressure chip is a vacuum cavity, and the other side is a sensing surface for receiving pressure to be measured; alternatively, the pressure chip 424 is a gage pressure chip, one side of which is a first sensing surface for receiving an equal pressure (e.g., atmospheric pressure), and the other side of which is a second sensing surface for receiving a pressure to be measured.

The first circuit board 421 and the second circuit board 422 may be rectangular with a length direction along a left-right direction, and the two pressure chips 424 may be arranged at intervals along the left-right direction. Correspondingly, the left and right sides of the first enclosing frame 423 and the second circuit board 422 enclose to form two left and right spaced second cavities 4272, and two pressure chips are arranged in the two second cavities 4272 in a one-to-one correspondence.

The middle portion of the first enclosure frame 423 and the first circuit board 421 and the second circuit board 422 together enclose one first cavity 4271, and one second cavity 4272 of the first enclosure frame is located between the first cavity 4271 and the other second cavity 4272. The front and rear side walls of the first enclosure frame 423 corresponding to the first cavity 4271 respectively protrude to front and rear sides to form side positioning portions 4233, and an upper end of the side positioning portions 4233 abuts against a lower surface of the first circuit board 421. In other embodiments, the edge of the second circuit board 422 that is crossed by the extension portion 4233 may be a concave edge, so that the outer edge of the extension portion 4233 is flush with the same front and rear side edges of the first peripheral frame 423 to reduce the front and rear width of the first peripheral frame 423. The first circuit board 421 may be provided with a plurality of tooling positioning holes 4236, and the tooling positioning holes 4236 surround the edge of the first peripheral frame 423, so that the first peripheral frame 423 can be accurately positioned relative to the first circuit board 421 through tooling positioning. Wherein, a plurality of second pins (not labeled) are fixed on the housing 410. The upper end of the second contact pin extends upwards into the upper part of the mounting cavity, and is provided with a fisheye structure 4085, and the fisheye structure 4085 is tightly matched with the other plurality of metallized connecting holes 4211 arranged on the left side and the right side of the first circuit board 421 upwards, so that the pressure sensing component 420 can be fixed on the shell 410 through the plurality of fisheye structures from the left end and the right end respectively.

The pressure chip 424 is electrically connected to a plurality of pads on the second circuit board 422 through a first electrical connector 4251 (e.g., gold wire) located within the second cavity 4272, and the second circuit board 422 is electrically connected to a second electrical connector 4213 (e.g., a plurality of pads) on the first circuit board 421 through a second electrical connector 4252 (e.g., gold wire) located within the first cavity 4271; the first and second chambers 4271 and 4272 are filled with a first protective gel (not shown).

The differential pressure sensor 400 of the present utility model further comprises a first pressure tube 405 for introducing a first pressure into the first pressure chamber 4051 and a second pressure tube 406 for introducing a second pressure into the second pressure chamber 4061, the first pressure tube 405 and the second pressure tube 406 being integrally connectable to the housing 410.

Specifically, the first enclosure frame 423 may include a pair of walls 4231 extending up and down, wherein left and right sides of an upper end of the walls 4231 are adhered to the second circuit board 422, and left and right sides of the upper end of the walls 4231 are adhered to portions of edges of corresponding left and right ends of the first circuit board 421 protruding outwards relative to the second circuit board 422. The first enclosure 423 further includes two partitions 4234 to divide a space enclosed between the first enclosure 423 and the first and second circuit boards 421 and 422 into a first cavity 4271 and two second cavities 4272. The first enclosure 423 may further include a plate 4232 fixed to a lower end of the wall 4231, where three windows 428 are formed in the plate 4232. The first chamber 4271 is in communication with the first pressure chamber 4051 and the interior chamber 4052 of the first pressure tube 405 through one of the windows 428 and the second chamber 4272 is in communication with the second pressure chamber 4061 and the interior chamber 4062 of the second pressure tube 406 through another of the windows 428.

Wherein the plate 4232 may be adhesively supported downwardly on a generally horizontal support surface 409 formed on the housing 410. The support surface 409 is provided with two through holes 4091 which are opposite to the two windows 428 in a one-to-one correspondence manner, and the lower ends of the two through holes 4091 are opposite to the first pressure chamber 4051 and the second pressure chamber 4061 in a one-to-one correspondence manner. The periphery of the via hole 4091 is recessed inwards to form a circle of second sealing groove 413, the periphery of each window 428 is downward to form a circle of sealing flange 4235 correspondingly inserted into the second sealing groove 413, and the second sealing groove 413 is internally provided with first sealing adhesive.

Preferably, the left and right ends of the housing are fixedly connected with an electrical connector 404, a plurality of first pins 408 are fixedly arranged on the electrical connector 404, first ends 4081 of the first pins extend inwards into the upper part of the mounting cavity, the first ends 4081 are formed with fish-eye structures 4084, and the fish-eye structures 4084 are tightly fitted in metallized connecting holes arranged at the left and right corresponding ends of the first circuit board.

Preferably, the upper surface of the first circuit board is provided with an electronic element 429, the periphery of the electronic element 429 is provided with a second surrounding frame, and the second surrounding frame is filled with second protective gel.

Claims

1. A differential pressure sensor, comprising:

a housing defining a mounting cavity, including a shell (410), an upper cover (430) and a lower cover (440);

the pressure sensing assembly (420) is arranged in the mounting cavity and divides the mounting cavity into an upper part and a lower part, and the lower part of the mounting cavity comprises a first pressure cavity (4051) and a second pressure cavity (4061) which are isolated from each other; the pressure sensing assembly comprises a first circuit board (421) horizontally arranged, a second circuit board (422) adhered to the lower side surface of the first circuit board (421), a first surrounding frame (423) adhered to the lower side surface of the second circuit board (422), and two pressure chips (424);

a first pressure tube (405) for introducing a first pressure into the first pressure chamber (4051) and a second pressure tube (406) for introducing a second pressure into the second pressure chamber (4061);

the first enclosing frame (423) and the first circuit board (421) and the second circuit board (422) are enclosed together to form a first cavity (4271), the first enclosing frame (423) and the second circuit board (422) are enclosed to form two left and right spaced second cavities (4272), and the two pressure chips are arranged in the two second cavities (4272) in a one-to-one correspondence manner; the pressure chip (424) is electrically connected with the second circuit board (422) through a first electrical connector (4251) positioned in the second cavity (4272), and the second circuit board (422) is electrically connected with the first circuit board (421) through a first electrical connector (4251) positioned in the first cavity (4271); the first pressure cavity (4051) and the second pressure cavity (4061) are communicated to the two second cavities (4272) in a one-to-one correspondence; the first cavity (4271) and the second cavity (4272) are filled with a first protective gel; one second cavity (4272) is located between the other second cavity (4272) and the first cavity (4271), front and rear side walls of the first surrounding frame (423), which correspond to the first cavity (4271), respectively protrude to front and rear sides to form side positioning parts (4233), and the upper ends of the side positioning parts (4233) are abutted to the lower surface of the first circuit board (421).

2. The differential pressure sensor according to claim 1, wherein the first enclosure (423) includes a wall (4231) extending up and down, and two partitions (4234) integrally connected to the wall (4231), and the partitions (4234) divide a space enclosed between the first enclosure (423) and the second circuit board (422) into one of the first chamber (4271) and two of the second chambers (4272).

3. The differential pressure sensor according to claim 2, characterized in that the first peripheral frame (423) further comprises a plate (4232) fixed to the lower end of the wall (4231), wherein three windows (428) are formed in the plate (4232) in one-to-one correspondence with the first chamber (4271) and the two second chambers (4272), and the two second chambers (4272) are communicated to the corresponding pressure chambers through the corresponding windows (428).

4. A differential pressure sensor according to claim 3, characterized in that the plate (4232) is fixedly supported downwards on a support surface (409) formed on the housing (410); two through holes (4091) which are opposite to the two windows (428) in a one-to-one correspondence manner are formed in the supporting surface (409).

5. The differential pressure sensor of claim 4, wherein the periphery of the via hole (4091) is recessed inward to form a circle of second sealing groove (413), the periphery of each window (428) is downward to form a circle of sealing flange (4235) correspondingly inserted into the second sealing groove (413), and the second sealing groove (413) is provided with first sealing adhesive.

6. The differential pressure sensor according to claim 1, wherein the upper cover (430) comprises a cover plate (431) and a flange (432) formed by downwardly protruding a horizontal edge of the cover plate (431), an upper end edge of the housing (410) correspondingly forms a circle of first sealing grooves (407), and inner and outer sides of the first sealing grooves (407) correspondingly form a circle of inner peripheral walls (4072) and a circle of outer peripheral walls (4073); the flange (432) is correspondingly inserted into the first sealing groove (407), and the first sealing groove (407) is filled with second sealing adhesive.

7. The differential pressure sensor according to claim 1, wherein the left and right ends of the housing (410) are fixedly connected with an electrical connector (404), a plurality of first pins (408) are fixedly arranged on the electrical connector (404), the first ends (4081) of the first pins (408) extend inwards into the upper part of the mounting cavity, the first ends (4081) are formed with fish-eye structures (4084), and the fish-eye structures (4084) are tightly fitted upwards into metallized connecting holes (4211) arranged at the left and right corresponding ends of the first circuit board (421).

8. The differential pressure sensor according to claim 1, characterized in that the upper surface of the first circuit board (421) is provided with an electronic component (429), the periphery of the electronic component (429) is provided with a second enclosing frame, and the second enclosing frame is filled with a second protective gel.