A differential pressure sensor

Abstract

The present invention relates to the technical field of pressure sensors, and discloses a differential pressure sensor, comprising a detection core, the detection core comprising a base, a circuit board and two pressure-sensitive chips, the circuit board being bonded to the top of the base, the pressure-sensitive chip being electrically connected to the upper surface of the circuit board; the circuit board being provided with a first through hole concentric with the pressure-sensitive chip; the lower portion of the base being provided with a first cavity and a second cavity, both of which are provided with a vertical second through hole. By arranging the pressure-sensitive chip on the upper surface of the circuit board, and sealing and protecting the top of the pressure-sensitive chip with a protective member, and also sealing and protecting the bottom of the pressure-sensitive chip with a second colloid filled in the first through hole on the circuit board and the second through hole in the base that is connected to the first through hole, the packaging position of the pressure-sensitive chip is changed to avoid corrosion, and at the same time, the elasticity of the protective glue is used to reduce the pressure generated by the measured medium after freezing, thereby extending its service life.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure sensors, and in particular to a differential pressure sensor. Background Art

[0002] A differential pressure sensor (DPS) is a sensor used to measure the difference between two pressures. It is typically used to measure the pressure difference between the front and rear ends of a device or component. The most typical application is to measure the exhaust pressure difference between the front and rear channels of an automobile engine exhaust particulate filter.

[0003] In the prior art, nitrogen oxides (NOx) and particulate matter, such as smoke and water vapor, output by vehicle engines easily crystallize and freeze at low temperatures. The excessive pressure generated when the particulate matter crystallizes and freezes can damage the chip. At the same time, nitrogen oxides form an acidic solution when they come into contact with water vapor, which easily corrodes the sensor chip and circuits. Therefore, it is best to isolate the sensor pressure-sensing chip from pollutants. Therefore, a differential pressure sensor is proposed to solve the above-mentioned problems. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the shortcomings of the existing technology, the present invention provides a differential pressure sensor with the advantages of corrosion resistance and anti-freezing, which solves the problem that the differential pressure sensor in the existing technology is easily corroded and the chip is damaged by particle crystal freezing.

[0006] (2) Technical solution

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0008] A differential pressure sensor includes a housing, a detection core disposed within the housing, the detection core comprising a base, a circuit board, and two pressure-sensitive chips, the circuit board being bonded to the top of the base, and the pressure-sensitive chips being electrically connected to the upper surface of the circuit board;

[0009] The circuit board is provided with a first through hole which is concentric with the pressure sensing chip;

[0010] A first cavity and a second cavity are formed at the lower portion of the base, and a vertical second through hole is formed in both the first cavity and the second cavity;

[0011] The second through hole is coaxial with the first through hole, and the sum of the diameters of the second through hole is greater than the diameter of the first through hole. The second through hole and the first through hole are both filled with a first protective glue.

[0012] Preferably, a protective member is installed on the circuit board, and two packaging holes concentric with the pressure-sensing chip are provided on the protective member, and the packaging holes are filled with a second protective glue.

[0013] Preferably, a positioning groove is provided on the upper surface of the base, and the positioning groove matches the circuit board and is used to position the circuit board.

[0014] Preferably, a mounting groove adapted to the detection core is provided in the shell for mounting the detection core.

[0015] Preferably, the shell is further provided with limiting grooves distributed on the front and rear sides of the installation groove; the base is further provided with limiting blocks; the limiting blocks correspond to the positions of the limiting grooves and are adapted in size.

[0016] Preferably, the installation groove is further installed with a second flow guide pipe and a first flow guide pipe, and the second flow guide pipe and the first flow guide pipe are both connected to an air pipe, and the air pipe is fixedly connected to the lower end of the shell.

[0017] Preferably, the second flow guide tube is adapted to the second cavity and is located in the second cavity; the first flow guide tube is adapted to the first cavity and is located in the first cavity.

[0018] (3) Beneficial effects

[0019] Compared with the prior art, the present invention provides a differential pressure sensor with the following beneficial effects:

[0020] 1. The differential pressure sensor is configured by arranging a pressure-sensitive chip on the upper surface of a circuit board, sealing and protecting the top of the pressure-sensitive chip with a protective member, and sealing and protecting the bottom of the pressure-sensitive chip with a second colloid filled in a second through-hole connected to the first through-hole provided in a base through a first through-hole on the circuit board. The packaging position of the pressure-sensitive chip is changed to prevent corrosion, and the elasticity of the protective glue reduces the pressure generated by the freezing of the measured medium, thereby extending its service life.

[0021] 2. In the differential pressure sensor, the diameter of the second through hole is greater than the diameter of the first through hole, and the first protective glue gradually becomes smaller from bottom to top, thereby increasing the effective pressure-sensing area. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of embodiment 1.

[0023] Figure 2 This is a schematic diagram of the explosion structure of Example 1.

[0024] Figure 3 This is a schematic structural diagram of the detection core in Example 1.

[0025] Figure 4 This is a schematic diagram of the structure of the circuit board in Example 1.

[0026] Figure 5 This is a schematic diagram of the structure of the circuit board in Example 1.

[0027] Figure 6 Schematic diagram of the structure of the substrate in Example 1.

[0028] Figure 7 Schematic diagram of the structure of the substrate in Example 1.

[0029] Figure 8 Schematic diagram of another structure of the base in Example 1

[0030] Figure 9 This is a schematic diagram of another structural circuit board in Example 1.

[0031] In the figure: 10 shell, 101 first air guide tube, 102 second air guide tube, 103 installation groove, 104 limit groove, 20 upper cover, 30 detection core, 31 circuit board, 311 first through hole, 312 gold wire bonding part, 313 pressure sensing part, 32 base, 321 second cavity, 322 first cavity, 323 second through hole, 324 first protective glue, 325 limit block, 326 detection cavity, 327 through hole, 328 positioning groove, 33 pressure sensing chip, 34 protective part, 341 second protective glue, 342 packaging hole, 35 chip, 11 electrical connector, 12 air pipe. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] See also Figure 1-9 A differential pressure sensor includes a shell 10, a mounting groove 103 is provided in the shell 10, a detection core 30 is provided in the mounting groove 103, an upper cover 20, an electrical connector 11 and an air pipe 12 are connected to the shell 10; the electrical connector 11 and the detection core 30 are electrically connected; the upper cover 20 covers the detection core 30; the air pipe 12 is fixedly connected to the lower part of the shell 10, and is connected to the second flow guide pipe 102 and the first flow guide pipe 101 in the mounting groove 103, and is used to send the detected gas into the detection core 30 to detect the pressure difference, and transmit the pressure difference signal through the electrical connector.

[0034] like Figure 8-9As shown, a structure of a detection core 30 is provided, which includes a base 32, a circuit board 31 and two pressure-sensitive chip parts 313. The circuit board 31 is bonded to the top of the base 32, and the pressure-sensitive part 313 is located between the bonding surfaces of the circuit board 31 and the base 32. A vertical arrangement corresponding to the position of the pressure-sensitive part 313 is opened on the base 32, and a detection cavity 326 is provided at the lower part of the base 32. The detection cavity 326 is arranged on the periphery of the through hole 327, and glue is poured in the through hole 327 to isolate the pressure-sensitive part 313 from smoke and water vapor to avoid crystallization and freezing at low temperatures, and to avoid being subjected to pressure and corrosion.

[0035] However, since the pressure-sensing portion 313 is arranged below the circuit board 31, the contact area during crystal freezing and detection is large, resulting in a small proportion of the effective pressure-sensing area of the pressure-sensing portion 313, and it is easily affected by temperature and drifts. Therefore, another structure is proposed.

[0036] like Figure 1-7 As shown, further, the detection core 30 includes a base 32, a circuit board 31 and two pressure-sensitive chips 33. The circuit board 31 is bonded to the top of the base 32, and the pressure-sensitive chips 33 are electrically connected to the upper surface of the circuit board 31;

[0037] The circuit board 31 is provided with a first through hole 311 which is concentric with the pressure sensing chip 33; the lower part of the base 32 is provided with a first cavity 322 and a second cavity 321, the second guide tube 102 is adapted to the second cavity 321 and is located in the second cavity 321; the first guide tube 101 is adapted to the first cavity 322 and is located in the first cavity 322; a vertical second through hole 323 is provided on each of the first cavity 322 and the second cavity 321; the second through hole 323 is coaxial with the first through hole 311, and the diameter of the second through hole 323 is greater than the diameter of the first through hole 311, and the second through hole 323 and the first through hole 311 are coaxial. 1 is filled with a first protective glue 324, which gradually becomes smaller from bottom to top; the pressure is transmitted to the pressure-sensing chip 33 for detection through the second through hole 323, the first through hole, and the first protective glue 324, and the first protective glue 324 gradually becomes smaller from bottom to top, thereby reducing the pressure-sensitive area of the pressure-sensing chip 33, increasing the effective pressure-sensing area, improving detection accuracy, and reducing the influence of temperature on it. In addition, it also avoids the problem that nitrogen oxides form an acidic solution when they meet water vapor, which is easy to corrode the sensor chip and circuits. The pressure-sensing chip 33 is arranged above the circuit board 31, which is also easier to produce and assemble.

[0038] Furthermore, a protective part 34 is installed on the circuit board 31. Two packaging holes 342 concentric with the pressure-sensing chip 33 are opened on the protective part 34. The packaging holes 342 are filled with a second protective glue 341. The second protective glue 341 and the protective part 34 form an enclosed space to protect the pressure-sensing chip 33 from external corrosion, and the structure of the two can also make the connection of the pressure-sensing chip 33 more stable.

[0039] Furthermore, a gold wire bonding portion 312 is provided on the circuit board 31, and the gold wire bonding portion 312 and the pressure sensing chip 33 are connected by gold wires; the circuit board 31 can be connected to the electrical connector 11 by aluminum wire bonding, soldering or laser welding;

[0040] Furthermore, an installation groove 103 adapted to the detection core 30 is opened in the shell 10 for installing the detection core 30, and a limiting groove 104 is also provided in the shell 10 on the front and rear sides of the installation groove 103; a limiting block 325 is also provided on the base 32; the limiting block 325 corresponds to the position of the limiting groove 104 and is adapted in size; a positioning groove 328 is provided on the upper surface of the base 32, and the positioning groove 328 matches the circuit board 31 and is used to position the circuit board 31; the connection between the base 32 and the circuit board 31 is more stable, and the base 32 is more stably installed in the shell 10, and it is also convenient for production assembly.

[0041] When using:

[0042] (1) The measured fluid enters the first cavity 322 and the second cavity 321 through the air pipe 12. The pressure of the measured fluid acts on the second protective glue 341, and then the pressure-sensing chip 33 detects the pressure. At the same time, the second protective glue 341 and the first protective glue 324 encapsulate and protect the pressure-sensing chip 33 to prevent corrosion.

[0043] In summary, by arranging a pressure-sensitive chip 33 on the upper surface of the circuit board 31, and sealing and protecting the top of the pressure-sensitive chip 33 with a protective member 34, and sealing and protecting the bottom of the pressure-sensitive chip 33 through the first through hole 311 on the circuit board 31 and the second through hole 323 provided in the base 32 and connected to the first through hole 311, the second colloid 324 is filled in the inside, and the packaging position of the pressure-sensitive chip 33 is changed to avoid corrosion. At the same time, the elasticity of the protective glue is used to reduce the pressure generated by the measured medium after freezing, thereby extending its service life, thereby solving the problems in the prior art of differential pressure sensors that are susceptible to corrosion and the chip being damaged by freezing of particles.

[0044] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A differential pressure sensor, comprising a housing (10), wherein a detection core (30) is provided in the housing (10), characterized in that: The detection core (30) comprises a base (32), a circuit board (31) and two pressure-sensitive chips (33), wherein the circuit board (31) is bonded to the top of the base (32), and the pressure-sensitive chips (33) are electrically connected to the upper surface of the circuit board (31); The circuit board (31) is provided with a first through hole (311) concentric with the pressure sensing chip (33); A first cavity (322) and a second cavity (321) are provided at the lower portion of the base (32), and a vertical second through hole (323) is provided on both the first cavity (322) and the second cavity (321); The second through hole (323) and the first through hole (311) are coaxial, and the diameter of the second through hole (323) is larger than the diameter of the first through hole (311); the second through hole (323) and the first through hole (311) are both filled with a first protective glue (324); The housing (10) is provided with a mounting groove (103) adapted to the detection core (30) for mounting the detection core (30); The housing (10) is further provided with limiting grooves (104) distributed on both sides of the mounting groove (103) in front and behind. A limiting block (325) is further provided on the base (32). The limiting block (325) corresponds to the position of the limiting groove (104) and is adapted in size. The top surface of the limiting block (325) is provided with a groove extending along the width direction of the circuit board (31).

2. A differential pressure sensor according to claim 1, characterized in that: A protective member (34) is installed on the circuit board (31), and two packaging holes (342) concentric with the pressure-sensing chip (33) are provided on the protective member (34), and a second protective glue (341) is filled in the packaging holes (342).

3. The differential pressure sensor according to claim 1, wherein: A positioning groove (328) is provided on the upper surface of the base (32), and the positioning groove (328) matches the circuit board (31) and is used for positioning the circuit board (31).

4. The differential pressure sensor according to claim 1, wherein: The installation groove (103) is further provided with a second flow guide pipe (102) and a first flow guide pipe (101), and the second flow guide pipe (102) and the first flow guide pipe (101) are both connected to an air pipe (12), and the air pipe (12) is fixedly connected to the lower end of the housing (10).

5. The differential pressure sensor according to claim 4, characterized in that: The second flow guide tube (102) is adapted to the second cavity (321) and is located in the second cavity (321); the first flow guide tube (101) is adapted to the first cavity (322) and is located in the first cavity (322).

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