CN114459663A - Novel capacitance pressure sensor - Google Patents

Abstract

The invention belongs to the technical field of pressure sensors, and particularly provides a novel capacitive pressure sensor, which comprises: the pressure sensing device comprises an outer shell, an inner shell, a pressure sensing element, a circuit module, an upper end cover, a contact pin and a connecting wire; the inner circuit is wrapped up by insulating and highly waterproof casting glue, including having saved that the gap department of revealing of casing and upper end cover sets up procedures such as O type circle or applys sealed glue, waterproof grade can reach IP69, avoided the sensor at corrosivity, dirty, when using under the humid environment such as moisture, because of the risk of the sensor inner circuit short circuit that the intaking leads to, waterproof performance is excellent, the total insulating properties is far above the withstand voltage requirement of exchanging 1800V in fields such as commercial air conditioner household electrical appliances, saved the inside loaded down with trivial details structure that sets up insulating paper and bottom edge set up insulating washer that sets up of current pressure sensor when having insulating properties, the cost of labor of the insulating paper book system and insulating washer's processing cost have been saved.

Description

Novel capacitance pressure sensor

Technical Field

The invention belongs to the technical field of pressure sensors, and particularly relates to a novel capacitive pressure sensor.

Background

The voltage output accuracy of the pressure sensor is easily influenced by electromagnetic interference and conductive fluid of the pressure sensor and external electronic products, transient overvoltage exceeding normal working voltage can be generated due to factors such as equipment starting and stopping, power grid impact, faults or lightning stroke in the working process of the pressure sensor, a conditioning circuit of the pressure sensor is communicated with a shell, after a conductive path is formed between a power supply and the conditioning circuit and between the power supply and the shell, when the transient overvoltage passes through the conductive path, the conditioning circuit and a pressure detection component can be punctured, and the pressure sensor is prone to failure. At present, the household electrical appliances trade generally requires that resistant insulating properties between product electricity connector contact pin and the shell reaches exchange 1800V at least, duration 1S does not have the puncture, in order to reach this requirement, set up the metal shielding cover structure in current pressure sensor mostly inside, the outside compresses tightly electrical connector for the riveting portion of bending, because all adopt be metal casing, outer metal casing and inner shield cover metal casing are in order to avoid directly switching on, clearance department uses insulating paper parcel in the middle of it, the human cost that insulating scroll made the cylinder structure has been increased, the bottom edge then adopts high temperature resistant corrosion-resistant and insulating thermoplasticity solid material, use CNC processing or the scheme of moulding plastics also corresponding material cost that has increased and assemble this part' S cost of labor. In addition, the existing sensor has the problems that a leakage gap appears at the riveting connection position of metal and an electric connector, water vapor easily enters, an O-shaped ring needs to be arranged or sealant needs to be applied, and the corresponding material cost and the labor cost are increased.

Fig. 1 shows a conventional pressure sensor, in which an electrical connection mode is formed by quickly connecting a standard connector 21 (terminal) and a plug-in unit 22 in a plug-in manner, and a waterproof grade is generally IP65, and the waterproof grade is very easy to cause internal water inflow under humid environments such as corrosion, dirt, and water vapor, and thus internal circuits are short-circuited, so that the pressure sensor fails. And the standard connector 21 and counter-insert 22 of existing pressure sensors add to the part cost.

Therefore, the invention provides a novel capacitive pressure sensor which has excellent mechanical properties, low production cost, high temperature resistance, corrosion resistance, high water resistance and high insulation.

Disclosure of Invention

The invention aims to solve the problems of high production cost and easy failure of the pressure sensor in the prior art of the pressure sensor.

Therefore, the invention provides a novel capacitive pressure sensor, which comprises: the outer shell, the inner shell, the upper end cover and the connecting line; the pressure sensing element and the circuit module are sequentially arranged in the second accommodating cavity from bottom to top, and an inner shell through hole communicated with the second accommodating cavity is formed in the bottom of the inner shell; the upper end cover is matched with an opening of the second accommodating cavity, and the pressure sensing element and the circuit module are packaged in the second accommodating cavity; the top of the upper end cover is provided with a contact pin, the top end of the contact pin is welded with the connecting wire, and the bottom end of the contact pin is connected with the circuit module; a first accommodating cavity is formed in the outer shell, and the inner shell is installed in the first accommodating cavity; pouring sealant into the first accommodating cavity, and encapsulating the inner shell and the upper end cover in the first accommodating cavity; and the bottom of the outer shell is provided with an outer shell through hole communicated with the inner shell through hole.

Specifically, a groove is formed in the bottom surface of the second accommodating cavity, which is in contact with the pressure sensing element; and a sealing ring is arranged in the groove and is in contact with the pressure sensing element.

Specifically, the inner shell through hole comprises a first through hole and a second through hole which are communicated with each other; the second through hole is communicated with the through hole of the outer shell; the aperture of the second through hole is larger than that of the first through hole, and the first through hole is not coaxial with the through hole of the outer shell.

Specifically, the bottom of the outer shell is provided with a cavity; the top surface of the cavity is provided with an opening which is communicated with the through hole of the outer shell; and the top of the cavity is provided with a thimble protruding downwards.

Specifically, the outer portion of the inner shell and the first accommodating cavity are provided with mutually matched threads, and the inner shell is installed in the first accommodating cavity through the threads.

Specifically, the pressure sensing element is a ceramic capacitance pressure sensing element; the circuit module is an FPC flexible conditioning circuit module.

Specifically, the outer shell is a polyimide outer shell, a glass fiber reinforced PBT outer shell or a glass fiber reinforced PPS outer shell.

Specifically, the inner shell is a metal inner shell.

Specifically, the connecting wire is wrapped by an insulating layer.

Specifically, the pouring sealant submerges the contact pin and the welding point of the connecting wire and covers the lower end of the connecting wire by 0.4-1 cm.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the novel capacitive pressure sensor provided by the invention has the advantages of low production cost, excellent waterproof performance and good insulating strength, and is not easy to lose efficacy in corrosive, dirty, moisture-containing and other humid environments.

(2) The novel capacitive pressure sensor outer shell provided by the invention can be prepared from polyimide, glass fiber reinforced PBT (polybutylene terephthalate) or glass fiber reinforced PPS (polyphenylene sulfide), so that the novel capacitive pressure sensor outer shell has excellent mechanical strength, high temperature resistance, corrosion resistance and insulating property; the FPC flexible conditioning circuit module is processed by grounding the inner wall of the metal inner shell to ensure that an electromagnetic field generated inside the FPC flexible conditioning circuit module is stopped in the metal inner shell, the outer surface of the metal inner shell resists electromagnetic interference generated outside, the FPC flexible conditioning circuit module is connected with the ceramic capacitance pressure sensing element, after instantaneous large current or large voltage generated in the circuit flows through the FPC flexible conditioning circuit module, the ceramic capacitor pressure sensing element and the metal inner shell through the contact pin, flowing to the outer casing, the insulation property of the outer casing prevents the circuit from continuing to be conducted, in addition, the gap between the outer casing and the side wall of the inner casing is provided with insulating pouring sealant, when the pouring sealant is made of epoxy resin and the thickness of the epoxy resin at the gap is 0.8-1mm, the breakdown field strength is as high as 35KV/mm, the total insulation performance of the high-voltage alternating current transformer is far higher than the withstand voltage requirement of alternating current 1800V in the fields of commercial air-conditioning household appliances and the like.

(3) The novel capacitive pressure sensor provided by the invention cancels the complicated structure that the insulating paper is arranged in the existing pressure sensor and the insulating gasket is arranged at the edge of the bottom of the existing pressure sensor, and saves the labor cost of rolling the insulating paper and the processing cost of the insulating gasket while keeping the insulating property; the internal circuit of the sensor provided by the invention is completely wrapped by the insulating and highly waterproof pouring sealant, so that the processes of arranging an O-shaped ring or applying the sealant at the leakage gap between the inner shell and the upper end cover and the like are omitted, the waterproof grade can reach IP69, and the risk of short circuit of the internal circuit of the sensor caused by water inflow when the sensor is used in corrosive, dirty, moisture-containing and other humid environments is avoided; in addition, due to the strong adhesive force of the pouring sealant, the pouring sealant can be bonded with the outer shell and the inner shell after being cured, has excellent mechanical properties, and can be used for fixedly mounting the inner shell in the outer shell even without depending on the locking force of matched threads on the outer shell and the inner shell in low-pressure application; the pressure resistance and the explosion resistance of the sensor are further enhanced by the pouring sealant structure of the accommodating cavity at the upper end of the outer shell.

The present invention will be described in further detail below with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic structural diagram of a conventional pressure sensor.

Fig. 2 is a schematic cross-sectional view of the novel capacitive pressure sensor provided by the present invention.

Fig. 3 is a schematic structural diagram of an outer shell of the novel capacitive pressure sensor provided by the invention.

Fig. 4 is a bottom view of the outer casing of the novel capacitive pressure sensor provided by the invention.

Fig. 5 is a schematic structural diagram of an inner housing of the novel capacitive pressure sensor provided by the invention.

Fig. 6 is a schematic diagram of an external structure of an upper end cap and a contact pin of the novel capacitive pressure sensor provided by the invention.

Fig. 7 is a schematic diagram of an external structure of a pressure sensing element of the novel capacitive pressure sensor provided by the present invention.

Fig. 8 is an exploded view of the main structure of the novel capacitive pressure sensor provided by the present invention.

Description of reference numerals: 1. an outer housing; 2. a first accommodating cavity; 3. a through hole of the outer shell; 4. a thimble; 5. a cavity; 6. a thread; 7. an inner housing; 8. a second accommodating cavity; 9. a first through hole; 10. a second through hole; 11. a groove; 12. a pressure sensing element; 13. a circuit module; 14. an upper end cover; 15. inserting a pin; 16. a connecting wire; 17. pouring a sealant; 18. a seal ring; 19. a convex bayonet; 20. a card slot; 21. a connecting member; 22. and (6) inserting the plug-in.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Although representative embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications and changes may be made thereto without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and equivalents thereof.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention; the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, whereby the features defined "first", "second" may explicitly or implicitly include one or more of such features.

Referring to fig. 2 and 8, the present invention provides a novel capacitive pressure sensor comprising: the outer shell 1, the inner shell 7, the upper end cover 14 and the connecting line 16; a second accommodating cavity 8 is formed in the inner shell 7, a pressure sensing element 12 and a circuit module 13 are sequentially mounted in the second accommodating cavity 8 from bottom to top, and an inner shell through hole communicated with the second accommodating cavity 8 is formed in the bottom of the inner shell 7; the upper end cover 14 is matched with an opening of the second accommodating cavity 8, and the pressure sensing element 12 and the circuit module 13 are packaged in the second accommodating cavity 8; a contact pin 15 is arranged at the top of the upper end cover 14, the top end of the contact pin 15 is welded with the connecting wire 16, and the bottom end of the contact pin 15 is connected with the circuit module 13; a first accommodating cavity 2 is formed in the outer shell 1, and the inner shell 7 is installed in the first accommodating cavity 2; pouring sealant 17 into the first accommodating cavity 2, and encapsulating the inner shell 7 and the upper end cover 14 in the first accommodating cavity 2; and an outer shell through hole 3 communicated with the inner shell through hole is formed in the bottom of the outer shell 1.

Further, a groove 11 is formed in the bottom surface of the second accommodating cavity 8, which is in contact with the pressure sensing element 12; a sealing ring 18 is arranged in the groove 11, and the sealing ring 18 is in contact with the pressure sensing element 12. The amount of compression of the seal ring 18 can be controlled by controlling the depth of the groove 11. The groove 11 is preferably annular, the sealing ring 18 is preferably an O-shaped ring, the HNBR which is corrosion-resistant, tear-resistant, wear-resistant, compression deformation-resistant, high-temperature and low-temperature resistant and insulating is adopted as the material, and the compression amount of the sealing ring 18 is 20-25%, so that the sealing ring has a better sealing effect.

As shown in fig. 5, the inner housing through-holes include a first through-hole 9 and a second through-hole 10 that penetrate each other; the second through hole 10 is communicated with the through hole 3 of the outer shell; the aperture of the second through hole 10 is larger than that of the first through hole 9, and the first through hole 9 is not coaxial with the through hole 3 of the outer shell. When the capacitance pressure sensor is used in places such as air conditioners and the like which can generate high-pressure fluid media, fluid sequentially enters the first through hole 9 and the second through hole 10 through the outer shell through hole 3, and the first through hole 9 and the outer shell through hole 3 are not coaxial, and the second through hole 10 can be used as a buffer area, so that the high-pressure fluid is prevented from directly acting on the pressure sensing element 12 above the first through hole 9 in the vertical direction to cause the damage of the pressure sensing element 12.

Further, referring to fig. 3 and 4, a cavity 5 is formed at the bottom of the outer shell 1, and an opening communicated with the outer shell through hole 3 is formed in the top surface of the cavity 5 to maintain the outer shell through hole 3 to be communicated with the outside. In order to facilitate the installation and fixation of the capacitance pressure sensor, the top of the cavity 5 is also provided with a thimble 4 protruding downwards, and the thimble 4 can be designed into a solid cylinder coaxial with the cavity 5. When the capacitance pressure sensor is installed on an air conditioner, the valve core of a fluorine injection nozzle (filling valve) at the butt joint part is jacked open by the thimble 4, and a channel of a refrigerant flowing through the pressure sensor is opened. When the pressure sensor needs to be replaced, the valve core of the fluorine injection nozzle (filling valve) is closed, the refrigerant channel is closed, and the refrigerant in the pipeline can be prevented from overflowing.

As shown in fig. 3 and 5, the outer part of the inner housing 7 and the first receiving cavity 2 are provided with threads 6, which are engaged with each other, and the inner housing 7 is installed in the first receiving cavity 2 by the threads 6. The thread 6 can be a fine thread, and the diameter is preferably M15. The connection of the thread 6 prevents the pouring compound 17 from flowing out of the connection between the outer housing 1 and the inner housing 7. In addition, when outside medium loops through shell body through-hole 3 and interior casing through-hole, because the sealed of fine tooth screw thread, the medium only a few part can permeate shell body 1 and the lateral wall clearance department of interior casing 7, and because the sealing effect of the casting glue 17 of the internal solidification of first holding chamber 2, avoided the medium of infiltration to get into circuit structure, so here need not to set up O type circle again and can guarantee the inside leakproofness of pressure sensor.

In a refined embodiment: the pressure sensing element 12 is a ceramic capacitance pressure sensing element, preferably made of 96% ceramic material, and has excellent characteristics of strong corrosion resistance, impact resistance, high elasticity and the like, and meanwhile, when the ceramic capacitance pressure sensor works in a working range of-40 ℃ to 135 ℃ due to extremely high thermal stability of the ceramic capacitance, pressure directly acts on a sensing diaphragm of the ceramic capacitance pressure sensing element, and capacitance change between a base electrode and the diaphragm electrode is in proportional relation with the pressure. When the pressure is recovered, the performance of the pressure sensing diaphragm is not influenced, and the defect that the traditional pressure sensing diaphragm is invalid due to low-range overload is overcome;

the circuit module 13 is an FPC flexible conditioning circuit module, the base material of the FPC flexible conditioning circuit module is organic polymer material PI polyimide with good bending resistance, the temperature resistance is over 400 ℃, the temperature range of long-term use is-200-300 ℃, the bending strength of the polyimide enhanced by graphite and glass fiber can reach 345MPa, and the FPC flexible conditioning circuit module has high insulating property;

the outer shell 1 is a polyimide outer shell, a glass fiber reinforced PBT outer shell or a glass fiber reinforced PPS outer shell, and is preferably prepared from high-temperature-resistant, corrosion-resistant and high-insulation polyimide, the polyimide is one of organic high polymer materials with the best comprehensive performance, the high-temperature resistance is more than 400 ℃, the long-term use temperature range is-200-300 ℃, the high-temperature-resistant and high-insulation composite material has excellent mechanical performance, the tensile strength is more than 100MPa, the bending strength at 20 ℃ is more than 170MPa, and the dielectric strength is as high as 300KV/mm, and belongs to F-H-level insulation. In addition, the outer shell 1 can also adopt the glass fiber reinforced modified PBT which is added by 20 to 40 percent, and the PBT has high temperature resistance, flame retardance, high mechanical strength, good fatigue resistance and excellent electrical insulation. The glass fiber reinforced PPS with high temperature resistance, mechanical impact resistance and electrical insulating property can also meet the requirements of the outer shell 1;

the inner shell 7 is preferably made of a metal material having electromagnetic shielding resistance, and the inner shell 7 made of brass, SUS304, SUS316, aluminum alloy, carbon steel, or the like can meet the requirements;

the upper end cover 14 is prepared from PEE + PA + GF 30% or PBT + GF 30%, the two materials are both resistant to corrosion and high temperature, and 30% of glass fiber is added, so that the mechanical property is more excellent;

the contact pin 15 is plated with tin on the surface of phosphor copper with good welding performance and good conductivity, and preferably, the contact pin 15 and the upper end cover 14 are in an integrated plastic sealing structure;

the pouring sealant 17 is epoxy resin, organic resin, room temperature vulcanized silica gel, polyamide or polyurethane hot melt adhesive and the like;

the connection lines 16 are output signal lines, 5V power supply lines, and ground lines.

In an optimized embodiment, the novel capacitive pressure sensor comprises: the device comprises an outer shell 1, an inner shell 7, a ceramic capacitance pressure sensing element, an FPC flexible conditioning circuit module, an upper end cover 14 and a connecting wire 16.

The inner shell 7 is made of brass which is strong in corrosion resistance, good in conductivity and easy to rivet, and the surface of the inner shell is passivated, so that the conductivity of the inner shell is reserved, and the corrosion resistance and the oxidation resistance of the inner shell are enhanced. Be equipped with the second holding chamber 8 that the wall thickness is 0.6-0.8mm in interior casing 7, interior casing 7 bottom is seted up and is run through 8 interior casing through-holes that lead to with second holding chamber, and through-hole diameter is 1.6mm, when high-pressure gas passes through interior casing through-hole, because the cross-sectional area of its formation is very little, according to the pressure computational formula: the pressure is equal to the pressure multiplied by the cross-sectional area, and the force applied to the sensing diaphragm of the ceramic capacitance pressure sensing element is within the range that the sensing diaphragm can bear. As shown in fig. 5, the top edge of the second accommodating cavity 8 is bent inward to form a bent portion with a reduced wall thickness, which not only satisfies the explosion-proof performance of the pressure sensor, but also facilitates the subsequent riveting bending. Fine threads are arranged at the position where the outer part of the inner shell 7 is connected with the outer shell 1 in an installing way, and the diameter of the threads is M15.

The ceramic capacitor pressure sensing element and the FPC flexible conditioning circuit module are sequentially arranged in the second accommodating cavity 8 from bottom to top; an annular groove 11 is formed in the bottom surface of the second accommodating cavity 8, which is in contact with the ceramic capacitor pressure sensing element; an O-shaped ring which is contacted with the ceramic capacitance pressure sensing element is arranged in the groove 11.

The top of the upper end cover 14 is provided with three pins 15 which are integrally injection-molded with the upper end cover 14, the pins 15 are exposed out of the surface of the upper end cover 14 by 3-5mm, and before being welded with a connecting wire 16, batch calibration and detection functions can be realized by contact conduction of a special spring type plug connector and the upper ends of the three pins 15. And the upper end cover 14 is buckled and pressed on the FPC flexible conditioning circuit module, so that the bottom end of the contact pin 15 is connected with the FPC flexible conditioning circuit module. Referring to fig. 6 and 7, a convex bayonet 19 is formed on the side of the upper end cover 14, a clamping groove 20 matched with the convex bayonet 19 is formed on the side of the ceramic capacitor pressure sensing element, when the ceramic capacitor pressure sensing element and the FPC flexible conditioning circuit module are packaged in the second containing cavity 8 of the inner housing 7 by using the upper end cover 14, the upper end cover 14 and the ceramic capacitor pressure sensing element form a whole, a risk of rotation cannot occur after the bending portion of the inner housing 7 is riveted, a subsequent positioning and screwing thread through the top of the upper end cover 14 or the upper edge of the inner housing 7 is avoided, and the inner housing 7 rotates along with rotation when the inner housing 7 is assembled into the outer housing 1.

The outer casing 1 is in an outer hexagon shape as shown in fig. 4, the distance between opposite sides of the hexagon is 26mm-27mm, a first accommodating cavity 2 is arranged in the outer casing 1, the thickness of the side wall of the first accommodating cavity 2 is 0.8mm-1mm, and the outer casing is made of high-temperature-resistant, corrosion-resistant and high-insulation polyimide. The part of the first containing cavity 2, which is connected with the inner shell 7, is provided with fine threads matched with the fine threads outside the inner shell 7. The bottom of the outer shell 1 is provided with an outer shell through hole 3 communicated with the inner shell through hole.

After the calibration and the detection are completed, the top end of the contact pin 15 and the connecting wire 16 wrapped with the insulating layer are subjected to lead-free tin soldering, the inner shell 7 is installed in the outer shell 1 through the thread 6 structure, pouring sealant 17 is injected into the first accommodating cavity 2 from the upper end of the outer shell 1, and the pouring sealant 17 is made of epoxy resin. The pouring sealant 17 is submerged in the welding point of the contact pin 15 and the connecting line 16, covers the lower end of the connecting line 16 by 0.4-1cm, and flows into the side wall gap between the outer shell 1 and the inner shell 7 through the action of gravity. After the pouring sealant 17 is cured, the internal circuit structure of the pressure sensor is completely wrapped by the pouring sealant 17 with excellent insulation resistance and waterproof performance, the waterproof grade can reach IP69, and the risk of short circuit of the internal circuit of the sensor caused by water inflow in humid environments such as corrosion, dirt, water vapor and the like is avoided. In addition, due to the strong adhesive force of the pouring sealant 17, the pouring sealant can be bonded with the outer shell 1 and the inner shell 7 after being cured, so that the mechanical strength, the shock resistance, the pressure resistance and the explosion resistance of the pressure sensor are enhanced, and the outer shell 1 and the inner shell 7 can be fixed together even in low-pressure application without depending on the locking force of the threads 6.

Because the curing period of the pouring sealant 17 is long, enough curing period needs to be reserved when pouring in batches, and under the dual evaluation of time cost and material cost, polyamide or polyurethane hot melt adhesive can also be used as the pouring sealant 17, and the process period is shortened by a low-pressure injection molding technology.

When the novel capacitive pressure sensor encounters instantaneous large current or large voltage generated in a circuit in use, current or voltage flows through the FPC flexible conditioning circuit module, the inner shell 7 and the ceramic capacitive pressure sensing element through the contact pin 15 and continues to flow to the outer shell 1, and the insulation characteristic of the outer shell 1 can prevent the circuit from continuing to be conducted. The thickness of the side wall at the upper end of the outer shell 1 is 0.8mm-1mm, the thickness of the epoxy resin insulated at the gap between the outer shell 1 and the side wall of the inner shell 7 is 0.8-1mm, the breakdown field strength is as high as 35KV/mm, and the total insulation performance is far higher than the withstand voltage requirement of alternating current 1800V in the fields of commercial air conditioners, household appliances and the like. The novel capacitive pressure sensor cancels the complicated structure that the insulating paper is arranged inside the existing pressure sensor and the insulating gasket is arranged at the edge of the bottom of the existing pressure sensor, and saves the labor cost of rolling the insulating paper and the processing cost of the insulating gasket.

The novel capacitive pressure sensor can be particularly applied to a central air conditioning system, and is particularly applied to a variable frequency air conditioner. When refrigerant pressure acts on ceramic capacitor pressure sensing element, the response diaphragm response pressure of ceramic capacitor pressure sensing element below, through taking place small distance deformation between inside bipolar plate, change the size of the inside variable capacitance of response diaphragm, and the reference capacitance of response diaphragm inside is unchangeable, utilize the characteristics of these two electric capacities, measure ratio between them, the PIN needle and the FPC flexible conditioning circuit module one end of ceramic capacitor pressure sensing element upper end are connected, produce the voltage signal output signal of being listed as along with pressure variation through the signal conditioning of FPC flexible conditioning circuit module. The output signal is connected with the lower end of the contact pin 15 through a small copper-clad round hole in the FPC flexible conditioning circuit module and is transmitted out through a connecting wire 16. The inner wall of the metal inner shell is in contact with two flexible thin plate-shaped pins with copper cladding separated from the FPC flexible conditioning circuit module, and charges generated by an electric field or a magnetic field are introduced into the ground by the grounding wire, so that the effect of preventing electromagnetic interference is achieved.

The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention.

Claims (10)

1. A novel capacitive pressure sensor, comprising: the device comprises an outer shell (1), an inner shell (7), an upper end cover (14) and a connecting wire (16); a second accommodating cavity (8) is formed in the inner shell (7), a pressure sensing element (12) and a circuit module (13) are sequentially mounted in the second accommodating cavity (8) from bottom to top, and an inner shell through hole communicated with the second accommodating cavity (8) is formed in the bottom of the inner shell (7); the upper end cover (14) is matched with an opening of the second accommodating cavity (8) to encapsulate the pressure sensing element (12) and the circuit module (13) in the second accommodating cavity (8); the top of the upper end cover (14) is provided with a contact pin (15), the top end of the contact pin (15) is welded with the connecting wire (16), and the bottom end of the contact pin is connected with the circuit module (13); a first accommodating cavity (2) is formed in the outer shell (1), and the inner shell (7) is installed in the first accommodating cavity (2); pouring sealant (17) into the first accommodating cavity (2), and encapsulating the inner shell (7) and the upper end cover (14) in the first accommodating cavity (2); and the bottom of the outer shell (1) is provided with an outer shell through hole (3) communicated with the inner shell through hole.

2. The novel capacitive pressure transducer of claim 1 wherein: a groove (11) is formed in the bottom surface of the second accommodating cavity (8) which is in contact with the pressure sensing element (12); and a sealing ring (18) is arranged in the groove (11), and the sealing ring (18) is contacted with the pressure sensing element (12).

3. The novel capacitive pressure transducer of claim 1 wherein: the through hole of the inner shell comprises a first through hole (9) and a second through hole (10) which are mutually communicated; the second through hole (10) is communicated with the outer shell through hole (3); the aperture of the second through hole (10) is larger than that of the first through hole (9), and the first through hole (9) and the outer shell through hole (3) are not coaxial.

4. The novel capacitive pressure transducer of claim 1 wherein: a cavity (5) is arranged at the bottom of the outer shell (1); the top surface of the cavity (5) is provided with an opening, and the opening is communicated with the through hole (3) of the outer shell; and the top of the cavity (5) is provided with a thimble (4) which protrudes downwards.

5. The novel capacitive pressure transducer of claim 1 wherein: the outer portion of the inner shell (7) and the first containing cavity (2) are internally provided with threads (6) which are matched with each other, and the inner shell (7) is installed in the first containing cavity (2) through the threads (6).

6. The novel capacitive pressure transducer of claim 1 wherein: the pressure sensing element (12) is a ceramic capacitance pressure sensing element; the circuit module (13) is an FPC flexible conditioning circuit module.

7. The novel capacitive pressure transducer of claim 1 wherein: the outer shell (1) is a polyimide outer shell, a glass fiber reinforced PBT outer shell or a glass fiber reinforced PPS outer shell.

8. The novel capacitive pressure transducer of claim 1 wherein: the inner shell (7) is a metal inner shell.

9. The novel capacitive pressure transducer of claim 1 wherein: the connecting line (16) is wrapped by an insulating layer.

10. The novel capacitive pressure transducer of claim 1 wherein: the pouring sealant (17) is submerged in the welding point of the contact pin (15) and the connecting wire (16) and covers 0.4-1cm of the lower end of the connecting wire (16).

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