A pressure sensor

Abstract

The application provides a pressure sensor, belonging to the technical field of sensors, comprising a shell, a pressure measurement assembly, a waterproof and breathable membrane and a piezoelectric vibration element, wherein the shell is provided with a mounting cavity, a pressure introduction channel and a breathable channel, the waterproof and breathable membrane is arranged on the breathable channel, and the piezoelectric vibration element is arranged above the waterproof and breathable membrane, which comprises a first electrode layer, a piezoelectric material layer and a second electrode layer, and is provided with a plurality of through holes corresponding to the breathable area of the waterproof and breathable membrane; the piezoelectric vibration element generates high-frequency vibration under the action of a driving voltage, transmits the vibration to the waterproof and breathable membrane, and atomizes and discharges the visible water mist attached to the waterproof and breathable membrane. The application quickly removes the visible water on the surface of the waterproof and breathable membrane in a vibration mode, ensures the unobstructed breathable channel, and has the advantages of low energy consumption, fast response, no thermal influence and the like.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and more specifically to a pressure sensor. Background Technology

[0002] A pressure sensor is a measuring device that converts pressure signals into electrical signals. It is widely used in fields such as monitoring intake manifold pressure in automotive engines and detecting atmospheric environmental parameters. In gauge pressure measurement applications, the sensor needs to simultaneously introduce the pressure medium to be measured and the ambient reference pressure, obtaining the relative pressure value through the difference between the two.

[0003] To prevent contaminants such as liquid water and dust from entering the sensor and damaging electronic components, vent holes are typically provided on the outer casing, and these vent holes are covered with a waterproof and breathable membrane. The waterproof and breathable membrane is often made of expanded polytetrafluoroethylene (PTFE), whose microporous structure allows gas molecules to pass freely while effectively blocking liquid water and particulate matter, thus protecting the internal pressure measurement components.

[0004] However, in actual use or testing, when the sensor is in a high-humidity environment or undergoes a cleaning process, water can easily accumulate on the surface of the waterproof and breathable membrane. The presence of this water can clog the micropores of the membrane, significantly reducing or even completely blocking air permeability. This prevents the sensor's internal reference pressure from keeping up with changes in ambient pressure, leading to measurement errors. This problem is particularly prominent in applications requiring high-precision measurements.

[0005] To address the aforementioned issues, existing technologies have proposed using heating elements to dry waterproof and breathable membranes. For example, a heating resistor can be installed inside a sensor to heat the waterproof and breathable membrane via thermal radiation or conduction, causing water vapor to evaporate from the membrane surface. However, this heating method has drawbacks such as high energy consumption, potential thermal impact on surrounding electronic components, and slow response speed. Summary of the Invention

[0006] In view of this, the present invention provides a pressure sensor to solve the problem in the prior art where the accumulation of water in the waterproof and breathable membrane leads to poor air permeability, which in turn affects the measurement accuracy.

[0007] To achieve the above-mentioned objective, the present invention provides a pressure sensor, comprising: A pressure sensor, comprising: The housing has an internal mounting cavity. A pressure interface tube is fixedly connected to the rear end of the housing. The outer wall of the pressure interface tube is equipped with a seal. The pressure interface tube has a pressure introduction channel that connects to the mounting cavity for introducing the pressure medium to be measured. The housing also has a venting channel for introducing the ambient reference pressure into the mounting cavity. The pressure measurement component, enclosed at one end of the pressure inlet channel, is used to receive the relative pressure of the medium under test relative to the ambient reference pressure. A waterproof and breathable membrane is installed on the ventilation channels; A piezoelectric vibration element is disposed above a waterproof and breathable membrane. The piezoelectric vibration element includes a first electrode layer, a piezoelectric material layer, and a second electrode layer. The first electrode layer and the second electrode layer are respectively disposed on opposite sides of the piezoelectric material layer. The piezoelectric vibration element has at least one through hole that penetrates the first electrode layer, the piezoelectric material layer, and the second electrode layer along the thickness direction. The through hole corresponds to at least a portion of the breathable area of ​​the waterproof and breathable membrane. The piezoelectric vibrating element generates high-frequency vibration under the action of driving voltage, and transmits the vibration to the waterproof and breathable membrane, so that the water adhering to the waterproof and breathable membrane is atomized and discharged.

[0008] Furthermore, the vibration direction of the piezoelectric vibrating element is its axial extension direction, which is along the thickness direction of the piezoelectric vibrating element, causing the piezoelectric vibrating element to undergo extension and contraction deformation in the thickness direction, thereby driving the waterproof and breathable membrane to vibrate along the thickness direction.

[0009] Furthermore, the through holes are circular, square, or slit-shaped, and multiple through holes are arranged in an array on the piezoelectric vibrating element.

[0010] Furthermore, the first electrode layer is electrically connected to the lower surface of the circuit board of the pressure measuring component through a first conductive adhesive, and the second electrode layer is electrically connected to the lower surface of the circuit board through leads.

[0011] Furthermore, the waterproof and breathable membrane is fixedly bonded to the lower surface of the piezoelectric vibration element by a first adhesive.

[0012] Furthermore, one end of the ventilation channel faces upward and connects to the installation cavity, with a waterproof and breathable membrane placed at one end of the ventilation channel.

[0013] Furthermore, the bottom of the mounting cavity protrudes upward to form a boss, and one end of the air vent extends upward to the top surface of the boss. The waterproof and breathable membrane is fixed to the top surface of the boss, and the piezoelectric vibration element is located above the waterproof and breathable membrane and has a gap or fits between it and the top surface of the boss.

[0014] Furthermore, the pressure measurement assembly includes: a substrate sealed to one end of the pressure inlet channel; a pressure-sensitive element fixed to the substrate and receiving the pressure of the medium to be measured and the ambient reference pressure and generating a corresponding differential pressure electrical signal; and a processing circuit disposed on the surface of the substrate and electrically connected to the pressure-sensitive element.

[0015] Furthermore, the piezoelectric vibrating element is electrically connected to a processing circuit, which includes a drive circuit for applying a drive voltage to the piezoelectric vibrating element. The drive voltage is an AC voltage with a frequency range of 20 kHz to 200 kHz, and the drive circuit is configured to drive the piezoelectric vibrating element intermittently.

[0016] Furthermore, the outer casing is provided with multiple terminals, and a fisheye pin is formed on the inner side of one end of each terminal. The pressure measurement component includes a circuit board with multiple metallized connection holes. The fisheye pins are tightly fitted and electrically connected to the metallized connection holes. The circuit board has a C-shaped structure and is made of ceramic or metal material. An upper electrode layer and a lower electrode layer are respectively provided on the upper and lower surfaces of the circuit board. The upper electrode layer is electrically connected to the processing circuit through a conductive adhesive, and the lower electrode layer is electrically connected to the piezoelectric vibration element.

[0017] The working principle of the pressure sensor of this invention is as follows: The pressure medium to be measured enters through the pressure introduction channel and acts on one side of the pressure-sensitive element; the ambient reference pressure enters the mounting cavity through the venting channel, the through hole on the piezoelectric vibration element, and the waterproof and breathable membrane, acting on the other side of the pressure-sensitive element. The pressure-sensitive element outputs an electrical signal based on the pressure difference between the two sides, which is processed by the processing circuit and then output outward to achieve pressure measurement. When water accumulates on the outer surface of the waterproof and breathable membrane, the driving circuit applies an AC driving voltage to the piezoelectric vibration element. The piezoelectric vibration element generates high-frequency vibration along the thickness direction and transmits the vibration to the waterproof and breathable membrane, causing the water on the membrane surface to atomize into tiny water droplets and be discharged outward, restoring the venting channel to its original state and ensuring accurate introduction of the reference pressure.

[0018] Compared with the prior art, the present invention has the following beneficial effects.

[0019] This invention employs a piezoelectric vibration element to drive a waterproof and breathable membrane to generate high-frequency vibration, atomizing the water adhering to the membrane surface into tiny droplets and discharging them outwards. This quickly restores the patency of the breathable channels, ensuring the accurate introduction of environmental reference pressure and effectively solving the measurement error problem caused by water blockage. Compared to existing heating and drying methods, the vibration atomization drainage method of this invention consumes less energy, has a faster response speed, and does not cause thermal effects on surrounding electronic components, making it particularly suitable for applications sensitive to power consumption and heat.

[0020] In this invention, the piezoelectric vibration element adopts a three-layer stacked structure consisting of a first electrode layer, a piezoelectric material layer, and a second electrode layer, with through holes formed in it. This ensures effective generation and transmission of piezoelectric vibration while avoiding blockage of the air passage, achieving functional compatibility between vibration drainage and gas permeation. The through holes can adopt various shapes and array distributions, such as circular holes, square holes, or slit-like holes, and can be optimized according to specific air permeability and vibration intensity requirements, providing good design flexibility. Simultaneously, the first and second electrode layers are connected to the circuit board via conductive adhesive and leads, respectively, achieving a reliable electrical connection. The adhesive also serves to fix the piezoelectric vibration element, resulting in a compact structure and simple assembly. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of the pressure sensor according to the first embodiment of the present invention; Figure 2 This is a schematic diagram of a piezoelectric vibration element.

[0022] The components are as follows: 1. Outer shell; 10. Mounting cavity; 11. Main shell; 11a. Recess; 11b. Vent hole; 12. Top cover; 111. Electrical connection part; 112. Pressure interface pipe; 1120. Pressure introduction channel; 1121. Seal; 113. Hot riveting post; 114. Boss; 115. Support part; 2. Pressure measuring assembly; 20. Pressure-sensitive element; 21. Annular sealing gasket; 21a. Center hole; 22. Base plate; 22a. Pressure through hole; 23. Circuit board; 23a. Stepped hole; 23b. Ventilation through hole; 23c. Metallized connection hole; 201. Lead wire; 231. Upper electrode layer; 232. Lower electrode layer; 3. Terminal; 4a. Fisheye pin; 4b. Fisheye pin; 5. Sealant; 6. Waterproof and breathable membrane; 71. First adhesive; 81. First conductive adhesive; 9. Piezoelectric vibration element; 91. First electrode layer; 92. Piezoelectric material layer; 93. Second electrode layer; 94. Through hole. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] First Embodiment Reference Figure 1 and Figure 2 In this embodiment, the pressure sensor mainly includes a housing 1, a pressure measuring component 2, a waterproof and breathable membrane 6, and a piezoelectric vibration element 9.

[0025] The housing 1 includes a main housing 11 and a top cover 12, which are connected by a sealant 5. An installation cavity 10 is formed inside the housing 1. A pressure interface pipe 112 is fixedly connected to the rear end of the housing 1, and a seal 1121 is provided on the outer wall of the pressure interface pipe 112. At least partially, a pressure introduction channel 1120 is defined inside the pressure interface pipe 112, with one inner end of the pressure introduction channel 1120 communicating with the installation cavity 10 for introducing the pressure medium to be measured. The housing 1 also has a vent channel for introducing an ambient reference pressure into the installation cavity 10. An electrical connection portion 111 is provided on the housing 1, with one inner end of several terminals 3 extending into the installation cavity 10 and electrically connected to the pressure measuring assembly 2.

[0026] A ventilated channel is provided on the main housing 11, including vertically extending vent holes 11b, one end of which connects to the environment and the other end connects to the bottom of the mounting cavity 10. A boss 114 is formed by the inward protrusion of the bottom of the cavity 11a of the main housing 11. A waterproof and breathable membrane 6 is disposed above the boss 114. The waterproof and breathable membrane 6 is preferably made of expanded polytetrafluoroethylene (PTFE) material, having a microporous structure that allows gas to pass through while blocking liquid water.

[0027] like Figure 2 A piezoelectric vibrating element 9 is disposed above the waterproof and breathable membrane 6. The piezoelectric vibrating element 9 includes a first electrode layer 91, a piezoelectric material layer 92, and a second electrode layer 93. The first electrode layer 91 and the second electrode layer 93 are respectively disposed on opposite sides of the piezoelectric material layer 92, and are formed, for example, by sputtering, vapor deposition, or screen printing. The piezoelectric material layer 92 is preferably a piezoelectric ceramic material, such as lead zirconate titanate. The piezoelectric vibrating element 9 has a plurality of through holes 94, which penetrate the first electrode layer 91, the piezoelectric material layer 92, and the second electrode layer 93 along the thickness direction. The through holes 94 are circular holes and are distributed in an array on the piezoelectric vibrating element 9. The through holes 94 correspond to the breathable areas of the waterproof and breathable membrane 6, ensuring that gas can pass through the piezoelectric vibrating element 9 to reach the waterproof and breathable membrane 6.

[0028] The first electrode layer 91 is electrically connected to the lower surface of the circuit board 23 of the pressure measuring assembly 2 via the first conductive adhesive 81. The second electrode layer 93 is electrically connected to the lower surface of the circuit board 23 via the lead wire 201. The waterproof and breathable membrane 6 is fixedly attached to the lower surface of the piezoelectric vibration element 9 via the first adhesive 71.

[0029] The piezoelectric vibrating element 9 is configured to generate high-frequency vibration under the action of a driving voltage. Specifically, when an AC driving voltage is applied between the first electrode layer 91 and the second electrode layer 93, the piezoelectric material layer 92 undergoes axial expansion and contraction deformation in the thickness direction. This deformation causes the piezoelectric vibrating element 9 to vibrate at a high frequency along the thickness direction, and transmits this vibration to the waterproof and breathable membrane 6. Since the piezoelectric vibrating element 9 is located above the waterproof and breathable membrane 6, it drives the waterproof and breathable membrane 6 to vibrate along the thickness direction during vibration, causing the clear water adhering to the lower surface (outer surface) of the waterproof and breathable membrane 6 to atomize and be discharged.

[0030] The pressure measurement assembly 2 includes a substrate 22, a pressure-sensitive element 20, and a circuit board 23. The substrate 22 has a pressure through-hole 22a extending through both sides. One outer end of the pressure through-hole 22a communicates with one inner end of the pressure inlet channel 1120 via the central hole 21a of an annular sealing gasket 21. The pressure-sensitive element 20 is sealed and fixed to the end of the pressure through-hole 22a furthest from the pressure inlet channel 1120, i.e., the upper end in the figure. Further, the pressure measurement assembly 2 may include the annular sealing gasket 21. The circuit board 23 is fixed to the upper side of the substrate 22, and the circuit board 23 may have a vent hole 23b. The upper surface of the circuit board 23 has a processing circuit electrically connected to the pressure-sensitive element 20 via leads. The circuit board 23 is a multilayer circuit board, and it has a stepped hole 23a surrounding the pressure-sensitive element 20 and the leads. The stepped hole 23a is filled with a protective gel covering the pressure-sensitive element 20 and the leads.

[0031] One end of terminal 3 faces upwards and has a fisheye pin 4a formed thereon. A plurality of metallized connection holes 23c are correspondingly provided on circuit board 23. The fisheye pin 4a is tightly fitted and electrically connected to the metallized connection holes 23c, thereby providing at least a portion of the clamping force. The pressure sensor may also include at least one fisheye pin 4b, the lower end of which is integrally molded into the main housing 11. The main housing 11 also protrudes upwards to form a plurality of hot-riveting posts 113, which press the circuit board 23 downwards.

[0032] When the pressure sensor is working, the pressure medium to be measured enters through the pressure inlet channel 1120 and acts on the lower surface of the pressure-sensitive element 20. The ambient reference pressure enters the mounting cavity 10 through the vent 11b, the through hole 94 on the piezoelectric vibration element 9, and the waterproof and breathable membrane 6, and acts on the upper surface of the pressure-sensitive element 20. The pressure-sensitive element 20 outputs a differential pressure electrical signal of the medium to be measured relative to the ambient reference pressure. After being processed by the processing circuit on the circuit board 23, the signal is led out from the electrical connection part 111 through the terminal 3 and the fisheye pin 4a.

[0033] When water accumulates on the surface of the waterproof and breathable membrane 6, the drive circuit in the processing circuit applies an AC drive voltage to the piezoelectric vibration element 9, with a frequency range of 20kHz to 200kHz, preferably 100kHz. The piezoelectric vibration element 9 generates high-frequency stretching vibration in the thickness direction, driving the waterproof and breathable membrane 6 to vibrate synchronously, causing the water on the lower surface of the membrane to atomize into micron-sized water droplets, which are then discharged outwards under the action of vibration, thereby restoring the unobstructed air passage.

[0034] The drive circuit can be configured to drive the piezoelectric vibrating element 9 intermittently, for example, driving it for 30 seconds every 10 minutes of operation. Alternatively, a humidity sensor or air permeability detection element can be placed near the waterproof and breathable membrane 6, automatically activating the drive when the detected air permeability is below a threshold.

[0035] Second Embodiment like Figure 1 and Figure 2 As shown, in the second embodiment, the circuit board 23 has a C-shaped structure and is made of ceramic or metal material. An upper electrode layer 231 is disposed on the upper surface of the circuit board 23, and a lower electrode layer 232 is disposed on the lower surface. The upper electrode layer 231 is electrically connected to the processing circuit via a conductive adhesive.

[0036] The first electrode layer 91 of the piezoelectric vibrating element 9 is electrically connected to the lower electrode layer 232 of the circuit board 23 via the first conductive adhesive 81. The second electrode layer 93 of the piezoelectric vibrating element 9 is electrically connected to the lower electrode layer 232 of the circuit board 23 or an independent ground point via the lead 201.

[0037] The circuit board 23 has a venting through-hole 23b that penetrates the upper and lower surfaces of the circuit board 23. One end of the venting through-hole 23b is connected to the waterproof and breathable membrane 6 through the through-hole 94 of the piezoelectric vibration element 9, and the other end is connected to the mounting cavity 10. The venting through-hole 23b is a metallized through-hole, and its inner wall is covered with a conductive metal layer.

[0038] In this embodiment, the waterproof and breathable membrane 6 is fixed to the top surface of the boss 114. The piezoelectric vibration element 9 is located above the waterproof and breathable membrane 6 and is fixedly attached to the waterproof and breathable membrane 6 by the first adhesive 71. The upper part of the piezoelectric vibration element 9 is connected to the lower electrode layer 232 of the circuit board 23 by the first conductive adhesive 81.

[0039] The C-shaped plate structure in this embodiment provides better structural strength and electrical conductivity. Other structural features are the same as in the first embodiment.

[0040] Third Embodiment In this embodiment, the through hole 94 is a slit-shaped hole, and multiple slit-shaped holes are distributed radially or parallelly on the piezoelectric vibrating element 9. This shape of through hole can reduce the weakening of the structural strength of the piezoelectric vibrating element 9 while ensuring the air permeability area, and helps to form a more uniform vibration distribution.

[0041] Other features of this embodiment are the same as those of the second embodiment.

[0042] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A pressure sensor, characterized in that, include: The outer shell (1) has an installation cavity (10) inside. A pressure interface pipe (112) is fixedly connected to the rear end of the outer shell (1). A sealing element (1121) is provided on the outer wall of the pressure interface pipe (112). A pressure introduction channel (1120) for introducing the pressure medium to be measured is provided inside the pressure interface pipe (112) and communicates with the installation cavity (10). The outer shell (1) is provided with a venting channel for introducing the ambient reference pressure into the installation cavity (10). The pressure measurement component (2) is enclosed at one end of the inner side of the pressure introduction channel (1120) and is used to receive the relative pressure of the medium to be measured relative to the ambient reference pressure. A waterproof and breathable membrane (6) is disposed on the breathable channel; A piezoelectric vibration element (9) is disposed above the waterproof and breathable membrane (6). The piezoelectric vibration element (9) includes a first electrode layer (91), a piezoelectric material layer (92), and a second electrode layer (93). The first electrode layer (91) and the second electrode layer (93) are respectively disposed on opposite sides of the piezoelectric material layer (92). At least one through hole (94) is provided on the piezoelectric vibration element (9). The through hole (94) penetrates the first electrode layer (91), the piezoelectric material layer (92), and the second electrode layer (93) along the thickness direction. The through hole (94) corresponds to at least a portion of the breathable area of ​​the waterproof and breathable membrane (6). The piezoelectric vibration element (9) generates high-frequency vibration under the action of driving voltage, and transmits the vibration to the waterproof and breathable membrane (6) so that the water adhering to the waterproof and breathable membrane (6) is atomized and discharged.

2. The pressure sensor according to claim 1, characterized in that, The vibration direction of the piezoelectric vibration element (9) is its axial extension direction, which is along the thickness direction of the piezoelectric vibration element (9), so that the piezoelectric vibration element (9) generates extension and contraction deformation in the thickness direction, thereby driving the waterproof and breathable membrane (6) to vibrate in the thickness direction.

3. The pressure sensor according to claim 1, characterized in that, The through hole (94) is a circular hole, a square hole or a slit-shaped hole, and multiple through holes (94) are arranged in an array on the piezoelectric vibration element (9).

4. The pressure sensor according to claim 1, characterized in that, The first electrode layer (91) is electrically connected to the lower surface of the circuit board (23) of the pressure measuring component (2) through the first conductive adhesive (81), and the second electrode layer (93) is electrically connected to the lower surface of the circuit board (23) through the lead wire (201).

5. The pressure sensor according to claim 1, characterized in that, The waterproof and breathable membrane (6) is fixedly bonded to the lower surface of the piezoelectric vibration element (9) by a first adhesive (71).

6. The pressure sensor according to claim 1, characterized in that, The inner end of the ventilation channel faces upward and connects to the mounting cavity (10), and the waterproof and breathable membrane (6) is disposed at the inner end of the ventilation channel.

7. The pressure sensor according to claim 6, characterized in that, The bottom of the mounting cavity (10) protrudes upward to form a boss (114). One end of the air-permeable channel extends upward to the top surface of the boss (114). The waterproof and breathable membrane (6) is fixed to the top surface of the boss (114). The piezoelectric vibration element (9) is located above the waterproof and breathable membrane (6) and has a gap or fits between it and the top surface of the boss (114).

8. The pressure sensor according to claim 1, characterized in that, The pressure measurement component (2) includes: A substrate (22) is sealed to one end of the pressure introduction channel (1120). A pressure-sensitive element (20) fixed to the substrate (22) and receiving the pressure of the medium under test and the ambient reference pressure to generate a corresponding differential pressure signal; and Processing circuit disposed on the surface of the substrate (22) and electrically connected to the pressure-sensitive element (20).

9. The pressure sensor according to claim 8, characterized in that, The piezoelectric vibrating element (9) is electrically connected to the processing circuit, which includes a drive circuit for applying a drive voltage to the piezoelectric vibrating element (9), the drive voltage being an AC voltage with a frequency range of 20 kHz to 200 kHz, and the drive circuit being configured to intermittently drive the piezoelectric vibrating element (9).

10. The pressure sensor according to claim 1, characterized in that, The outer casing (1) is provided with multiple terminals (3), and a fisheye pin (4a) is formed on the inner side of one end of the terminal (3). The pressure measuring component (2) includes a circuit board (23), and multiple metallized connection holes (23c) are provided on the circuit board (23). The fisheye pin (4a) is tightly fitted and electrically connected to the metallized connection hole (23c). The circuit board (23) has a C-shaped structure and is made of ceramic or metal material. An upper electrode layer (231) and a lower electrode layer (232) are provided on the upper and lower surfaces of the circuit board (23). The upper electrode layer (231) is electrically connected to the processing circuit through a conductive adhesive, and the lower electrode layer (232) is electrically connected to the piezoelectric vibration element (9).

Images