Differential pressure sensor

Abstract

A differential pressure sensor capable of reducing the risk that a pressure medium to be measured invades into the sensor comprises a shell which defines a mounting cavity and two mutually independent pressure introduction channels; the pressure measuring assembly is arranged in the mounting cavity; comprising a substrate of a processing circuit arranged on the surfaces of the two sides of the substrate. The frame body is fixed on one side of the back surface of the substrate and is provided with two first openings penetrating along the thickness direction of the substrate; the two absolute pressure type pressure sensitive elements are fixed on one side of the back surface of the substrate and are respectively arranged in two filling cavities enclosed by the two first openings and one side of the back surface of the substrate; one side, far away from the substrate, of the frame body is adhered to the shell, and one sides of the back surfaces of the two filling cavities are respectively communicated to one ends of the inner sides of the two pressure introduction channels in a sealing manner; the processing circuit comprises a first circuit part arranged on one side of the back surface of the substrate and a second circuit part arranged on one side of the front surface of the substrate; the filling cavities are filled with protective gel covering the corresponding pressure sensitive elements and the leads.

Description

Technical Field

[0001] This application relates to the technical field of sensors, and particularly to a differential pressure sensor. Background Art

[0002] Pressure sensors can be classified into absolute pressure sensors, differential pressure sensors, and gauge pressure sensors according to the measured pressure, and can be classified into capacitive pressure sensors, piezoresistive pressure sensors, piezoelectric pressure sensors, resonant pressure sensors, inductive pressure sensors, etc. according to the measurement principle. Among them, piezoresistive pressure sensors are widely used. They usually use a differential semiconductor pressure chip to receive high-pressure and low-pressure from both sides respectively. The pressure chip generates an electrical signal of corresponding magnitude according to the pressure difference on both sides. For a pressure medium to be measured with strong corrosiveness such as automobile exhaust, when the high-pressure and low-pressure are received on both sides of the pressure chip respectively, there is a risk that the pressure medium to be measured invades the interior of the sensor and corrodes the electronic components. Utility Model Content

[0003] Aiming at the deficiencies of the prior art, this application provides a differential pressure sensor to reduce the risk of the pressure medium to be measured invading the interior of the sensor.

[0004] To achieve the above object, this application provides the following technical solution: A differential pressure sensor, comprising:

[0005] A housing that defines an installation cavity and two independent pressure introduction channels;

[0006] And a pressure measurement assembly disposed in the installation cavity, including a substrate of a processing circuit disposed on both side surfaces of the substrate, a frame fixed to one side of the back surface of the substrate and having two first openings penetrating along the thickness direction of the substrate, and two absolute pressure sensitive elements fixed to one side of the back surface of the substrate and respectively disposed in two filling cavities surrounded by the two first openings and the back surface of the substrate. The side of the frame away from the substrate is bonded to the housing, and the back surfaces of the two filling cavities are respectively sealed and communicated with the inner ends of the two pressure introduction channels; the processing circuit includes a first circuit portion disposed on one side of the back surface of the substrate and a second circuit portion disposed on one side of the front surface of the substrate. The two pressure sensitive elements are electrically connected to the first circuit portion through leads; the filling cavities are filled with a protective gel covering the corresponding pressure sensitive elements and leads.

[0007] Preferably, it further includes a plurality of pins fixed to the housing. The inner ends of the pins extend into the interior of the housing and have an electrical connection surface exposed in the installation cavity, and the electrical connection surface is electrically connected to the second circuit portion.

[0008] Preferably, the front surface of the substrate is substantially flush with the electrical connection surface.

[0009] Preferably, the housing is recessed toward the back side to form a recess for accommodating at least a part of the pressure measurement assembly.

[0010] Preferably, each of the pressure introduction channels includes a first portion extending parallel to the substrate, and a second portion vertically communicating with one inner end of the first portion at one end, and the other end of the second portion communicates with the back end of the corresponding filling cavity.

[0011] Preferably, the first circuit portion includes a signal processing chip disposed on the front side of the substrate.

[0012] Preferably, the first circuit portion includes a signal processing chip disposed on the back side of the substrate and located in a receiving cavity formed on the frame.

[0013] Preferably, the receiving cavity is disposed between the two filling cavities, and is surrounded by a second opening penetrating through the frame in the thickness direction of the substrate and the back side of the substrate, and the back end of the second opening is sealed by the bottom surface of the mounting cavity.

[0014] Preferably, the housing further has a mechanical mounting portion, and mounting holes perpendicular to the substrate are provided on the mechanical mounting portion.

[0015] Preferably, a plurality of positioning portions for positioning the edge position of the substrate are provided on the inner wall of the mounting cavity. Description of the Drawings

[0016] Figure 1 Top view of the differential pressure sensor of the preferred embodiment;

[0017] Figure 2 For the cross-sectional view of the differential pressure sensor of the preferred embodiment along Figure 1 A - A shown in;

[0018] Description of the reference numerals: 10, mounting cavity; 11a, first positioning portion; 11b, second positioning portion; 11c, recess; 11d, convex portion; 11, main housing; 12b, steel ball; 12, upper cover; 14a, bushing; 14, mechanical mounting portion; 15, electrical connector; 1a, first portion; 1c, second portion; 1, housing; 20, protective gel; 21, substrate; 22a, filling cavity; 22b, receiving cavity; 22, frame; 2a, first pressure sensitive element; 2b, second pressure sensitive element; 2c, signal processing chip; 2, pressure measurement assembly; 3a, outer end; 3b, inner end; 3, pin. Detailed Description of the Preferred Embodiment

[0019] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. The following embodiments are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. In the following description, the same reference numerals are used to represent the same or equivalent elements, and repeated descriptions are omitted.

[0020] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0021] In addition, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0022] It should also be further understood that the term "and / or" used in the description of the present application and the corresponding claims refers to any combination of one or more of the listed items and all possible combinations.

[0023] As Figure 1 、 Figure 2 shown, the differential pressure sensor of the present utility model includes a housing 1. For the convenience of product assembly, it may include a main housing 11 and an upper cover 12 fixed to the upper side of the main housing 11. The main housing 11 and the upper cover 12 enclose an installation cavity 10. Two independent pressure introduction channels (not marked) for introducing the pressure medium to be measured are provided on the main housing 11, and the inner ends of the pressure introduction channels communicate with the installation cavity 10. A hole 12a may be provided on the upper cover 12, and the hole 12a may be sealed by a steel ball 12b.

[0024] A pressure measurement assembly 2 is provided in the installation cavity 10. The pressure measurement assembly 2 includes a substrate 21, a frame 22, and two absolute pressure type pressure sensitive elements 2a, 2b. The two absolute pressure type pressure sensitive elements 2a, 2b are spaced apart and arranged on the back side of the substrate 21 (i.e., Figure 2 the lower side in

[0025] Specifically, the substrate 21 may include a ceramic circuit board. On the back side of the circuit board, a first circuit portion of the processing circuit is provided. The first circuit portion is electrically connected to the pressure-sensitive elements 2a and 2b respectively through leads (not shown). On the front side of the pressure-sensitive elements 2a and 2b ( Figure 2 the upper side in Figure 2 ), it can be fixed to the back side of the circuit board by means of glue or soldering. The back side of the pressure-sensitive elements 2a and 2b, which is the pressure-sensing surface, is used to obtain the absolute pressure of the pressure medium to be measured. In some other solutions, the substrate 21 may further include a base plate (not shown) mounted on the back side of the circuit board. On the front side of the pressure-sensitive elements 2a and 2b (

[0026] the upper side in

[0027] ), it can be fixed to the back side of the base plate by means of glue or soldering. The base plate may be provided with a relief portion allowing the leads to pass through. Among them, the base plate can be made of materials with a relatively small linear expansion rate such as a ceramic plate or stainless steel.

[0028] The housing 22 can be hermetically bonded to the back side of the substrate 21 by glue 19. A glue receiving groove 18 can be formed on the main housing 11 for receiving the glue 19. The housing 22 has two first openings (not marked) penetrating in the thickness direction of the substrate 21. Two filling cavities 22a are formed by the upper ends of the first openings and the back side of the substrate 21. The side of the housing 22 away from the substrate 21 is hermetically bonded to the main housing 11 by glue, and the back sides of the two filling cavities 22a are respectively hermetically connected to the inner ends of the two pressure introduction channels. The absolute piezoelectric signals measured by the two pressure-sensitive elements 2a and 2b can be processed into differential piezoelectric signals by the processing circuit or by an external device. The filling cavities 22a are filled with a protective gel 20 covering the corresponding pressure-sensitive elements and leads.

[0029] For the differential pressure sensor of the present utility model, it is hermetically connected to the inner end of the pressure introduction channel through the housing 22, and at the same time, a filling cavity 22a for accommodating the protective gel 20 is formed by the housing 22 and the substrate 21, reducing the risk of the pressure medium to be measured invading the inside of the sensor while simplifying the structure of the sensor.

[0030] In some other solutions, preferably, the differential pressure sensor further includes a plurality of pins 3 fixed to the main housing 11. The inner end 3b of the pin 3 extends into the interior of the main housing 11 and has an electrical connection surface exposed in the installation cavity 10. The outer end 3a of the pin 3 extends outward into an electrical connector 15 formed on the side of the main housing 11. The electrical connection surface is electrically connected by a lead 23 to a portion of the processing circuit located on the front side of the substrate 21. Preferably, the main housing 11 can be recessed toward the back side to form a recess 11c for accommodating at least a part of the pressure measurement assembly 2, so that the front surface of the substrate 21 is substantially flush with the electrical connection surface, which is convenient for bonding by a bonding device to form a bonding lead 23. Correspondingly, the bottom of the installation cavity 10 can protrude toward the front side to form a protrusion 11d. The inner end 3b of the pin 3 is horizontally arranged and has an electrical connection surface formed on its upper side and exposed on the upper surface of the protrusion 11d.

[0031] Wherein, each of the pressure introduction channels includes a first portion 1a extending parallel to the substrate 21, and a second portion 1c vertically communicating with the inner end of the first portion 1a at one end. The other end of the second portion 1c communicates with the back end of the corresponding filling cavity 22a.

[0032] In some other solutions, preferably, the signal processing chip 2c is set as a component of the first circuit part, rather than as a component of the second circuit part. At this time, the signal processing chip 2c is arranged on the back side of the substrate 21. Preferably, the signal processing chip 2c can be located in a receiving cavity 22b formed on the housing 22. The receiving cavity 22b can also be filled with a protective gel to protect the signal processing chip 2c from being corroded by the pressure medium to be measured.

[0033] The receiving cavity 22b can be arranged between the two filling cavities 22a, and is surrounded by a second opening penetrating through the housing 22 in the thickness direction of the substrate 21 and the back side of the substrate 21. The back end of the second opening is sealed by the bottom surface of the installation cavity 10 with glue.

[0034] In some other solutions, preferably, the main housing 11 may further have a mechanical mounting portion 14. The mechanical mounting portion 14 is provided with a mounting hole (not marked) perpendicular to the substrate 21, and a bushing 14a can be arranged in the mounting hole.

[0035] The scope of the present disclosure is not limited by the detailed description, but is defined by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are construed as being included in the present disclosure.

Claims

1. A differential pressure sensor, characterized in that, Comprising: A housing (1) which defines an installation cavity (10) and two mutually independent pressure introduction channels; And a pressure measurement assembly (2) disposed in the installation cavity (10), including a substrate (21) of a processing circuit disposed on both side surfaces of the substrate (21), a frame body (22) fixed to one side of the back surface of the substrate (21) and having two first openings penetrating in the thickness direction of the substrate (21), and two absolute pressure type pressure sensitive elements (2a, 2b) fixed to one side of the back surface of the substrate (21) and respectively disposed in two filling cavities (22a) formed by the two first openings and the one side of the back surface of the substrate (21). The side of the frame body (22) away from the substrate (21) is adhered to the housing (1), and the back sides of the two filling cavities (22a) are respectively sealed and communicated to the inner ends of the two pressure introduction channels; the processing circuit includes a first circuit part disposed on one side of the back surface of the substrate (21) and a second circuit part disposed on one side of the front surface of the substrate (21). The two pressure sensitive elements (2a, 2b) are electrically connected to the first circuit part through leads; the filling cavities (22a) are filled with a protective gel (20) covering the corresponding pressure sensitive elements and leads.

2. The differential pressure sensor according to claim 1, wherein, It further includes a plurality of pins (3) fixed to the housing (1). The inner ends of the pins (3) extend into the interior of the housing (1) and have an electrical connection surface exposed in the installation cavity (10), and the electrical connection surface is electrically connected to the second circuit part.

3. The differential pressure sensor according to claim 2, wherein The front surface of the substrate (21) is substantially flush with the electrical connection surface.

4. The differential pressure sensor according to claim 2, wherein The housing (1) is recessed towards the back side to form a recess (11c) for accommodating at least a part of the pressure measurement assembly (2).

5. The differential pressure sensor according to claim 1, wherein Each of the pressure introduction channels includes a first part (1a) extending in parallel with the substrate (21), and a second part (1c) vertically connected to one end of the inner side of the first part (1a). The other end of the second part (1c) is communicated to the back end of the corresponding filling cavity (22a).

6. The differential pressure sensor according to any one of claims 1 to 5, characterized in that, The first circuit part includes a signal processing chip (2c) disposed on one side of the front surface of the substrate (21).

7. The differential pressure sensor according to any one of claims 1 to 5, characterized in that, The first circuit part includes a signal processing chip (2c) disposed on one side of the back surface of the substrate (21) and located in a receiving cavity (22b) formed on the frame body (22).

8. The differential pressure sensor according to claim 7, wherein, The receiving cavity (22b) is disposed between the two filling cavities (22a), and is formed by a second opening penetrating in the thickness direction of the substrate (21) on the frame body (22) and the one side of the back surface of the substrate (21). The back end of the second opening is sealed by the bottom surface of the installation cavity (10).

9. The differential pressure sensor according to any one of claims 1 to 5, characterized in that, The housing (1) further has a mechanical installation part (14), and the mechanical installation part (14) is provided with installation holes perpendicular to the substrate (21).

10. The differential pressure sensor according to any one of claims 1 to 5, characterized in that, A plurality of positioning parts for positioning the edge position of the substrate (21) are provided on the inner wall of the installation cavity (10).

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