CN220356565U

CN220356565U - Differential pressure sensor

Info

Publication number: CN220356565U
Application number: CN202321115944.4U
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: 2024-01-16
Anticipated expiration: 2033-05-07

Abstract

A differential pressure sensor, comprising: a housing defining a mounting cavity, including a shell and an upper 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 which are horizontally arranged; 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, and the first enclosing frame and the second circuit board are enclosed to form two 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 cavity and the second cavity are filled with the first protective gel, so that the service life of the pressure sensor can be prolonged.

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 shell and an upper 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 form a first cavity in an enclosing mode, the first enclosing frame and the second circuit board form two second cavities in an enclosing mode, and the two pressure chips are arranged in the two second cavities in a one-to-one correspondence mode; 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; the first cavity is located between the two second cavities, and a plurality of second electric connection parts used for enabling the lower surface of the first circuit board to be exposed to the yielding window in the first cavity are arranged on the second 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 opposite to the two windows are formed in the supporting surface in a one-to-one correspondence mode, and the two second cavities are communicated to the corresponding first pressure cavity or second pressure cavity through the window and the through holes.

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 other parts in the first sealing groove are filled with second sealing adhesive.

Preferably, the left end and the right end of the shell are fixedly connected with an electric connector, a plurality of contact pins are fixedly arranged on the electric connector, the first ends of the 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 a plurality of metallized connecting holes arranged on 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 a schematic diagram of an exploded structure of a differential pressure sensor according to a preferred embodiment of the present utility model;

FIG. 2 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. 3 is a perspective cross-sectional view of a pressure sensing assembly 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;

in the figure: 200. a differential pressure sensor; 202. a mounting part; 203. a bushing; 204. an electrical connector; 2051. a first pressure chamber; 2052. an inner cavity; 205. a first pressure tube; 2061. a second pressure chamber; 2062. an inner cavity; 206. a second pressure tube; 2071. a yielding slot; 2072. an inner peripheral wall; 2073. a peripheral wall; 207. a first seal groove; 2081. a first end; 2082. a second end; 2084. a fish-eye structure; 208. a contact pin; 2091. a via hole; 209. a support surface; 210. a housing; 211. a contact positioning portion; 212. positioning columns; 213. a second seal groove; 220. a pressure sensing assembly; 2211. metallized connecting holes; 2212. positioning the notch; 2213. a second electrical connection; 221. a first circuit board; 2220. a yield window; 222. a second circuit board; 2231. a wall; 2232. a plate; 2233. a side positioning part; 2234. a partition plate; 2235. a sealing flange; 223. a first enclosure; 224. a pressure chip; 2251. a first electrical connection; 2252. a second electrical connection; 2271. a first chamber; 2272. a second chamber; 228. a window; 2291. a second enclosure; 229. an electronic component; 230. an upper cover; 231. a cover plate; 232. a flange; 233. a protrusion; 234. steel balls; 236. fool-proof positioning part;

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.

Please refer to fig. 1 to 4. In a preferred embodiment of the present utility model, the differential pressure sensor 200 comprises a housing consisting of a housing 210 and an upper cover 230 that is snap-fitted downward onto the housing 210. The housing 210 and the upper cover 230 together define a mounting cavity (not labeled).

The pressure sensing component 220 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 2051 and a second pressure chamber 2061 that are isolated. The pressure sensing component 220 specifically includes a first circuit board 221 disposed horizontally, a second circuit board 222 adhered to a lower surface of the first circuit board 221, a first enclosure 223 adhered to a lower surface of the second circuit board 222, and two pressure chips 224. The pressure chip 224 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 224 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 221 and the second circuit board 222 may be rectangular with a length direction along a left-right direction, and the two pressure chips 224 may be disposed at intervals along the left-right direction. Accordingly, the left and right sides of the first surrounding frame 223 and the second circuit board 222 surround to form two left and right spaced second cavities 2272. Two pressure chips 224 are disposed in one-to-one correspondence within two second chambers 2272. The second circuit board 222 is provided with a plurality of second electrical connection parts 2213 for exposing the lower surface of the first circuit board 221 to the relief window 2220 in the first cavity 2271. The middle portion of the first enclosure frame 223 is enclosed with the first circuit board 221 and the second circuit board 222 to form a first cavity 2271, and the first cavity 2271 is located between the two second cavities 2272. Wherein, two sides of the left and right middle parts of the second circuit board 222 are respectively recessed inwards to form a positioning concave part (not labeled), and correspondingly, two sides of the left and right middle parts of the first circuit board 221 are respectively protruded downwards to form a side positioning part 2233, and the side positioning part 2233 is inserted into the positioning concave part on the corresponding side downwards. In other embodiments, at least one positioning recess 2212 may be disposed on each of the front and rear sides of the first circuit board 221, and correspondingly, the positioning posts 212 inserted upward into the positioning recesses 2212 are fixed on the housing 210.

The pressure chip 224 is electrically connected to a plurality of pads on the second circuit board 222 through a first electrical connection 2251 (e.g., gold wire) located in the second cavity 2272, and the second circuit board 222 is electrically connected to a second electrical connection 2213 (e.g., a plurality of pads) on the first circuit board 221 through a second electrical connection 2252 (e.g., gold wire) located in the first cavity 2271; the first and second chambers 2271 and 2272 are filled with a first protective gel (not shown).

The differential pressure sensor 200 of the present utility model further comprises a first pressure tube 205 for introducing a first pressure into the first pressure chamber 2051 and a second pressure tube 206 for introducing a second pressure into the second pressure chamber 2061, the first pressure tube 205 and the second pressure tube 206 being integrally connected to the housing 210.

Specifically, the first enclosure frame 223 may include a pair of walls 2231 extending up and down, wherein left and right sides of an upper end of the walls 2231 are adhered to the second circuit board 222, and left and right sides of the upper end of the walls 2231 are adhered to portions of edges of corresponding left and right ends of the first circuit board 221 protruding outwards relative to the second circuit board 222. The first surrounding frame 223 further includes two partitions 2234 to divide a space defined between the first surrounding frame 223 and the first and second circuit boards 221 and 222 into one first chamber 2271 and two second chambers 2272. The first enclosure 223 may further include a plate 2232 fixed to a lower end of the wall 2231, where three windows 228 are formed in the plate 2232. The first chamber 2271 communicates with the first pressure chamber 2051 and the inner chamber 2052 of the first pressure tube 205 through one of the windows 228 and the second chamber 2272 communicates with the second pressure chamber 2061 and the inner chamber 2062 of the second pressure tube 206 through the other of the windows 228.

Wherein the plate 2232 may be adhesively supported downwardly on a generally horizontal support surface 209 formed on the housing 210. Two through holes 2091 opposite to the two windows 228 are formed on the supporting surface 209, and the two second chambers 2272 are respectively communicated to the corresponding first pressure chamber 2051 or second pressure chamber 2061 through one window 228 and the through hole 2091. The periphery of the via hole 2091 is recessed inwards to form a circle of second sealing groove 213, the periphery of each window 228 is downward to form a circle of sealing flange 2235 correspondingly inserted into the second sealing groove 213, and the second sealing groove 213 is provided with first sealing adhesive.

In other embodiments, the upper cover 230 may preferably include a cover plate 231 and a flange 232 formed by downwardly protruding a horizontal edge of the cover plate 231, and an upper end edge of the housing 210 may correspondingly form a circle of the first sealing groove 207, and inner and outer sides of the first sealing groove 207 correspondingly form a circle of the inner peripheral wall 2072 and a circle of the outer peripheral wall 2073. The flange 232 is correspondingly inserted into the first sealing groove 207, and other parts in the first sealing groove 207 are filled with second sealing adhesive. Wherein the outer wall of the flange 232 may be outwardly convex to form a plurality of protrusions 233 to form a tight fit with the inner wall of the peripheral wall 2073.

The opposite left and right ends of the housing 210 may be fixedly connected with the electrical connector 204 and the mounting portion 202, the mounting portion 202 is provided with a mounting hole, and the mounting hole is provided with a bushing 203. The electrical connector 204 is fixedly provided with a plurality of pins 208, the first ends 2081 of the pins 208 extend inward into the upper portion of the mounting cavity, the first ends 2081 are formed with fish-eye structures 2084, the fish-eye structures 2084 are tightly fitted in the corresponding metallized connecting holes 2211 on the left and right corresponding ends of the first circuit board 221, and the second ends 2082 of the pins 208 are located in the electrical connector 204. The electronic component 229 other than the pressure chip 224 may be disposed on the upper surface of the first circuit board 221, and a second enclosure 2291 may be enclosed around the periphery of the electronic component, and the second enclosure 2291 may be filled with a second protective gel (not shown).

In other embodiments, the lower surface of the cover 231 is preferably provided with a stiffener (not shown) and the inner peripheral wall 2072 is provided with a relief notch 2071 for the stiffener to rest on. The inner wall of the abdication notch 2071 may be protruded inwards to form a plurality of spaced abutting positioning portions 211, and the abutting positioning portions 211 may be abutted inwards on the peripheral edge of the first circuit board 221. The upper cover 230 may further be provided with a fool-proof positioning portion 236 at a corner thereof for preventing errors during installation. The cover plate 231 may be provided with a steel ball hole, and the steel ball hole is sealed by a steel ball 234.

Wherein the second circuit board 222 may be a ceramic circuit board so that it is closer to the thermal expansion coefficient of the pressure die 224. The first and second peripheral frames 223 and 2291 may be made of plastic materials. The first protective gel and the second protective gel may be fluorosilicone gels, which may be the same or different.

The scope of the present disclosure is defined not by the detailed description but by the claims and their equivalents, and all modifications within the scope of the claims and their equivalents are to be construed as being included in the present disclosure.

Claims

1. A differential pressure sensor, comprising:

a housing defining a mounting cavity, including a shell (210) and an upper cover (230);

the pressure sensing assembly (220) 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 (2051) and a second pressure cavity (2061) which are isolated from each other; the pressure sensing assembly comprises a first circuit board (221) horizontally arranged, a second circuit board (222) adhered to the lower side surface of the first circuit board (221), a first surrounding frame (223) adhered to the lower side surface of the second circuit board (222), and two pressure chips (224);

a first pressure tube (205) for introducing a first pressure into the first pressure chamber (2051) and a second pressure tube (206) for introducing a second pressure into the second pressure chamber (2061);

the first enclosing frame (223) and the first circuit board (221) and the second circuit board (222) are enclosed together to form a first cavity (2271), the first enclosing frame (223) and the second circuit board (222) are enclosed to form two second cavities (2272), and the two pressure chips (224) are arranged in the two second cavities (2272) in a one-to-one correspondence manner; the pressure chip (224) is electrically connected with the second circuit board (222) through a first electrical connector (2251) positioned in the second cavity (2272), and the second circuit board (222) is electrically connected with the first circuit board (221) through the first electrical connector (2251) positioned in the first cavity (2271); the first pressure chamber (2051) and the second pressure chamber (2061) are communicated to the two second chambers (2272) in a one-to-one correspondence; the first cavity (2271) and the second cavity (2272) are filled with a first protective gel; the first cavity (2271) is located between the two second cavities (2272), and the second circuit board (222) is provided with a plurality of second electrical connection parts (2213) for exposing the lower surface of the first circuit board (221) to the yielding window (2220) in the first cavity (2271).

2. The differential pressure sensor according to claim 1, characterized in that the first enclosure (223) comprises a wall (2231) extending up and down and two separators (2234) integrally connected to the wall (2231), the separators (2234) dividing a space enclosed between the first enclosure (223) and the second circuit board (222) into one of the first chambers (2271) and two of the second chambers (2272).

3. The differential pressure sensor according to claim 2, characterized in that the first enclosure (223) further comprises a plate (2232) fixed to the lower end of the wall (2231), the plate (2232) being provided with three windows (228) in one-to-one correspondence with the first chamber (2271) and the two second chambers (2272), the two second chambers (2272) being connected to the corresponding pressure chambers by the corresponding windows (228).

4. A differential pressure sensor according to claim 3, characterized in that the plate (2232) is fixedly supported downwards on a support surface (209) formed on the housing (210); two through holes (2091) which are opposite to the two windows (228) in a one-to-one correspondence manner are formed in the supporting surface (209), and the two second cavities (2272) are communicated to the corresponding first pressure cavity (2051) or second pressure cavity (2061) through one window (228) and the through hole (2091) respectively.

5. The differential pressure sensor of claim 4, wherein the periphery of the via hole (2091) is recessed inward to form a ring of second sealing groove (213), the periphery of each window (228) is downward to form a ring of sealing flange (2235) correspondingly inserted into the second sealing groove (213), and the second sealing groove (213) is provided with the first sealing adhesive.

6. The differential pressure sensor according to claim 1, wherein the upper cover (230) comprises a cover plate (231) and a flange (232) formed by downwardly protruding a horizontal edge of the cover plate (231), the upper end edge of the housing (210) correspondingly forms a circle of first sealing grooves (207), and inner and outer sides of the first sealing grooves (207) correspondingly form a circle of inner peripheral walls (2072) and a circle of outer peripheral walls (2073); the flange (232) is correspondingly inserted into the first sealing groove (207), and other parts in the first sealing groove (207) are filled with second sealing adhesive.

7. The differential pressure sensor of claim 1, wherein the left and right ends of the housing (210) are fixedly connected with an electrical connector (204), a plurality of pins (208) are fixedly arranged on the electrical connector (204), first ends (2081) of the pins (208) extend inwards into the upper part of the mounting cavity, the first ends (2081) are formed with fisheye structures (2084), and the fisheye structures (2084) are tightly fitted upwards into a plurality of metallized connecting holes (2211) arranged on the left and right corresponding ends of the first circuit board (221).

8. The differential pressure sensor of claim 7, wherein the metallized connection hole (2211) is disposed on a portion of one side edge of the first circuit board (221) facing toward the exposed portion with respect to an edge of the second circuit board (222).

9. The differential pressure sensor according to claim 1, characterized in that the upper surface of the first circuit board (221) is provided with an electronic component (229), the periphery of the electronic component (229) is provided with a second enclosing frame (2291), and the second enclosing frame (2291) is filled with a second protective gel.