Passive NFC aircraft tire temperature and pressure composite sensor system

Abstract

The invention belongs to the technical field of sensors, and particularly relates to a passive NFC aircraft tire temperature and pressure composite sensor system which comprises a filler neck, a rear cover, a pressure core, a conversion circuit board, a conditioning circuit board assembly and a tag antenna assembly. The filler neck is a two-stage step column; the small-diameter end of the filler neck is provided with an air inlet, and the large-diameter end is provided with a cavity; the pressure core body is arranged in the air inlet hole; the pressure core body is connected with the conversion circuit board; the conversion circuit board is connected with the conditioning circuit board assembly; the conditioning circuit board assembly is fixed on the step surface of the cavity at the large-diameter end of the filler neck through a supporting screw; the tag antenna assembly is installed on the supporting screws through the fixing screws. The rear cover is screwed at the large-diameter end of the filler neck; the small-diameter end of the filler neck is connected with a tire through external threads.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a passive NFC aircraft tire temperature and pressure composite sensor system. Background Art

[0002] In the field of pressure sensor applications, customers need to design near-field communication temperature and pressure composite sensors in order to conveniently measure the pressure of the internal gas of aircraft tires in the landing gear system. Traditional wired tire pressure sensors require electrical connectors and cables to provide power. Wired active tire pressure sensors need to be powered by batteries, are large in size and weight, and need to be in working condition during flight. They are not suitable for the strong magnetic and strong vibration environment of the flight environment. Summary of the invention

[0003] The purpose of the present invention is to provide a passive NFC aircraft tire temperature and pressure composite sensor system, which realizes high-precision pressure and temperature composite measurement and output within a non-contact range of 10 cm (including 10 cm) based on the principle of near field communication. The system is small in size and easy to load and unload. The pressure core adopts an inverted structure, can measure a large pressure range of aircraft tires, and has good anti-electromagnetic interference ability and environmental adaptability.

[0004] The technical solution of the present invention is:

[0005] A passive NFC aircraft tire temperature and pressure composite sensor system, comprising: a nozzle, a rear cover, a pressure core, a conversion circuit board, a conditioning circuit board assembly, and a tag antenna assembly;

[0006] The nozzle is a two-stage step column; the small diameter end of the nozzle is provided with an air inlet hole, and the large diameter end is provided with a cavity;

[0007] The pressure core is arranged in the air inlet; the pressure core is connected to the conversion circuit board;

[0008] The conversion circuit board is connected to the conditioning circuit board assembly;

[0009] The conditioning circuit board assembly is fixed to the step surface of the cavity at the large diameter end of the nozzle by means of supporting screws;

[0010] The tag antenna assembly is mounted on the supporting screws by fixing screws;

[0011] The rear cover is screwed onto the large diameter end of the nozzle;

[0012] The small diameter end of the nozzle is connected to the tire through an external thread.

[0013] Furthermore, the pressure core is welded and sealed with the air inlet, and the air inlet is connected with the inside of the tire to form a closed cavity as a pressure sensing cavity, thereby transmitting the medium pressure to the pressure core 10 to achieve pressure measurement. The outer side is designed with a hexagonal shape, which is convenient for disassembly using a socket and a wrench.

[0014] Furthermore, the pressure core includes: a filter, a silicon piezoresistive chip, a tube shell and pins; the tube shell is a hollow tube with a flange at one end; the filter is welded to the end face of the tube shell without a flange; the silicon piezoresistive chip is sealed and bonded to the step surface of the hollow tube; the pins are welded to the pads of the silicon piezoresistive chip; and the flange edge of the tube shell is welded to the step surface of the air inlet of the nozzle.

[0015] The pressure core adopts leadless packaging technology, and the pins 18 are directly sintered to the pads of the silicon piezoresistive chip 16 through solder, eliminating the gold wire bonding process in traditional packaging and greatly reducing the core size.

[0016] Further, the conditioning circuit board assembly includes: a circuit board main board, a metal electromagnetic shielding cover;

[0017] The metal electromagnetic shielding cover is a cover-shaped structure with an open end, and three first threaded holes are opened on the end surface;

[0018] Three second threaded holes are opened at corresponding positions on the main board of the circuit board;

[0019] The supporting screws pass through the first and second threaded holes to fix the circuit board main board and the metal electromagnetic shielding cover on the step surface inside the large diameter end of the nozzle;

[0020] The end surface of the metal electromagnetic shielding cover is provided with a threading hole, and the shielding cover forms a metal shielding cavity, which can effectively protect against external electromagnetic interference.

[0021] Furthermore, an internal threaded hole is provided at the rear end of the supporting screw; the tag antenna assembly is screwed into the internal threaded hole at the rear end of the supporting screw through a fixing screw.

[0022] Furthermore, the back cover is made of non-metallic material to avoid shielding the field strength and ensure that the sensor is resistant to high temperature, corrosion and flame retardant. There is no power source inside the product, and there is no need to frequently remove the end cover. In order to improve the overall vibration resistance of the sensor, a sealing rubber ring is provided between the back cover and the nozzle, and a thread locking agent is applied to the threaded connection between the nozzle 9 and the non-metallic end cover 4, forming a closed shell with the non-metallic end cover 4 to provide physical protection for the internal circuit.

[0023] Furthermore, the conditioning circuit board assembly and the tag antenna assembly are connected via a wire, and a shielded heat shrink tubing is sleeved on the wire to enhance the anti-electromagnetic interference capability of the non-metallic end cap 4.

[0024] Furthermore, the working process of the system is as follows: the handheld device is close to the system, and the tag antenna assembly receives the transmission field strength signal of the handheld device; the tag antenna assembly converts the transmission field strength signal into an AC signal; the conditioning circuit board assembly converts the AC signal into a stable DC signal to power the pressure core; the pressure core collects the pressure signal; the conditioning circuit board assembly collects the temperature data and compensates the pressure signal according to the temperature data; the compensated pressure and temperature data are sent to the handheld device through the tag antenna assembly. The sensor performs wireless passive temperature and pressure composite monitoring based on the principle of near-field communication NFC, with a small size and easy loading and unloading. A temperature and pressure composite demodulation circuit based on near-field communication is designed to realize non-contact point-to-point communication function, and realize composite monitoring of tire pressure and temperature within a non-contact range of 10 cm or less.

[0025] The advantages and beneficial effects of the present invention are as follows: the present invention belongs to the field of sensors, and relates to the system design of manufacturing a small-size, high-pressure passive NFC aircraft tire temperature and pressure composite sensor. In the application field of military pressure sensors, in order to obtain high-pressure, high-precision wireless passive pressure and temperature tests on the ground, customers also need to meet the requirements that the product can cope with various extreme strong magnetic and high-vibration environments, and need to reduce the size of the sensor while ensuring reliability. Therefore, in the sensor design process, it is necessary to reduce the size of the core device pressure core and perform passive design of the sensor, which has great practical application value.

[0026] Specific advantages:

[0027] 1. The sensor performs wireless passive temperature and pressure composite monitoring based on the principle of near field communication (NFC). It is small in size and easy to load and unload. It does not contain any power source such as electrical connectors or batteries. It can meet the requirements of passive pressure and temperature composite monitoring within a non-contact range of 10 cm or less.

[0028] 2. The sensor adopts a small-size inverted pressure core with high pressure, which can achieve high pressure measurement of absolute pressure 0-10MPa;

[0029] 3. The nozzle, outer tube and bracket are designed as an integrated whole. The nozzle replaces the outer tube and bracket to reduce welding, achieve product miniaturization and improve structural strength to meet vibration test assessment;

[0030] 4. A metal shielding cover is designed on the conditioning circuit board. The shielding cover is pressed on the conditioning circuit board by three supporting screws to form a metal shielding cavity to meet the electromagnetic compatibility test assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic cross-sectional view of a pressure sensor;

[0032] Figure 2Schematic diagram of pressure sensor explosion;

[0033] Figure 3 A schematic cross-sectional view of a pressure sensitive component;

[0034] Figure 4 Schematic diagram of explosion of pressure sensitive components;

[0035] Figure 5 Cross-sectional view of the pressure core;

[0036] Figure 6 Working principle diagram;

[0037] Figure 7 Schematic diagram of signal conditioning circuit, linear voltage regulator circuit and near field communication circuit;

[0038] 1. Pressure sensitive component, 2. Conditioning circuit board assembly, 3. Tag antenna assembly, 4. Non-metallic end cap, 5. Screw, 6. Gasket, 7. Support screw, 8. Sealing rubber ring, 9. Take-over nozzle, 10. Flip-chip pressure core, 11. Conversion circuit board, 12. Circuit board main board, 13. Metal shielding cover, 14. Wire hole, 15. Filter, 16. Silicon piezoresistive chip, 17. Tube shell, 18. Pin. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0040] A system design for a passive NFC aircraft tire temperature and pressure composite sensor, which consists of a pressure sensitive component 1, a conditioning circuit board component 2, a tag antenna component 3, a non-metallic end cap 4, a screw 5, a gasket 6 and a support screw 7. The conditioning circuit board component 2 is provided with three mounting holes, which is connected to the pressure sensitive component 1 through a wire, and the conditioning circuit board component 2 and the metal shielding cover 13 are fixed to the threaded hole of the nozzle 9 through three support screws 7. The tag antenna component 3 is fixed to the mounting surface formed by the three support screws 7 through three screws 5 and a gasket 6, and is connected to the conditioning circuit board component 2 through a wire.

[0041] In order to manufacture a small-size, high-pressure passive NFC aircraft tire temperature and pressure composite sensor, the sensor was optimized in the following aspects.

[0042] 1 The sensor is based on the principle of near field communication (NFC) for wireless passive temperature and pressure composite monitoring. It is small in size and easy to load and unload. A temperature and pressure composite demodulation circuit based on near field communication is designed to realize non-contact point-to-point communication function and realize composite monitoring of tire pressure and temperature within a non-contact range of 10cm or less.

[0043] The conditioning circuit board assembly 2 is composed of a circuit board main board 12, a metal electromagnetic shielding cover 13 and a wire hole 14. The circuit board main board 12 includes a signal conditioning circuit, a linear voltage regulator circuit and a near-field communication circuit. When the tag antenna assembly 3 receives the electromagnetic field strength of the transmitting field, the near-field communication circuit on the circuit board main board 12 converts the alternating current signal into a voltage signal, and then powers the signal conditioning circuit and the communication circuit through the linear voltage regulator circuit. The signal conditioning circuit generates an excitation to power the pressure sensitive component 1. The pressure sensitive component 1 senses the pressure of the gas inside the tire, and the electrical signal is compensated for the entire temperature range through the demodulation circuit assembly 2. It is connected to the tag antenna assembly 3 to complete the demodulation and feedback of the near-field communication data, and output a non-contact digital signal proportional to the measured medium pressure and medium temperature.

[0044] 2. Design a small-size flip-chip pressure core with high pressure. The pressure core uses a silicon piezoresistive chip as a pressure-sensitive unit. To meet the high impact pressure environment, the sensitive unit needs to be packaged. The packaging structure of the sensitive unit consists of a filter 15, a silicon piezoresistive chip 16, a tube shell 17 and pins 18.

[0045] The filter 15 is a porous structure, which can filter out impurities in the air and prevent the impurities from accumulating on the silicon piezoresistive chip 16 and causing abnormal pressure sensitivity of the chip.

[0046] The pressure-sensitive element in the silicon piezoresistive chip 16 uses a silicon membrane as an elastic sensitive element, and adopts a square flat diaphragm form with peripheral fixed supports.

[0047] The tube shell 17 is made of stainless steel and provides physical protection for the internal silicon piezoresistive chip 16 .

[0048] The small-size flip-chip pressure core adopts leadless packaging technology, and the pins 18 are directly sintered to the pads of the silicon piezoresistive chip 16 through solder, eliminating the gold wire bonding process in traditional packaging and greatly reducing the size of the core.

[0049] 3. The nozzle, outer tube and bracket are designed as an integrated whole. The nozzle replaces the outer tube and bracket to reduce welding, achieve product miniaturization, improve structural strength and enhance the vibration resistance of the sensor.

[0050] The nozzle 9 is made of stainless steel and has good welding compatibility with the pressure core 10. The mechanical interface is provided with an external thread and connected to the tire air inlet of the aircraft. The front end is designed with an air inlet hole, which forms a pressure sensing cavity with the pressure core 10 fixed to the nozzle 9 by welding, thereby transmitting the medium pressure to the pressure core 10 to achieve pressure measurement. The outer side is designed with a hexagonal design, which is convenient for disassembly using a socket and a wrench.

[0051] The non-metallic end cap 4 is provided with an internal thread and an O-ring groove 8. The O-ring 8 is installed in the O-ring groove of the non-metallic end cap 4 and is screwed and connected to the nozzle 9 by a thread. It is made of polyetheretherketone material to avoid shielding the field strength and ensure that the sensor has high temperature resistance, corrosion resistance and flame retardancy. There is no power source inside the product, and the end cap does not need to be removed frequently. In order to improve the overall vibration resistance of the sensor, a thread locker is applied to the threaded connection between the nozzle 9 and the non-metallic end cap 4, and the non-metallic end cap 4 forms a closed shell to provide physical protection for the internal circuit.

[0052] A metal shielding cover 13 is designed on the conditioning circuit board assembly 2. The shielding cover is pressed on the circuit board main board 12 by three supporting screws 7 to form a metal shielding cavity, which can effectively protect against external electromagnetic interference. Two wire holes 14 are opened on the metal shielding cover. The conditioning circuit board 2 and the tag antenna assembly 3 are connected by wires. The wires are covered with shielding heat shrink tubing to enhance the anti-electromagnetic interference capability of the non-metallic end cap 4.

[0053] Example

[0054] A system design for a passive NFC aircraft tire temperature and pressure composite sensor, consisting of a pressure sensitive component 1, a conditioning circuit board component 2, a tag antenna component 3, a bracket 4, a metal outer tube 5, a non-metallic end cover 5, a screw 6, a gasket 7 and a support screw 8. The conditioning circuit board component 2 is provided with three mounting holes, which are connected to the pressure sensitive component 1 through wires, and the conditioning circuit board component 2 and the metal shielding cover 13 are fixed to the threaded holes of the nozzle 9 through three support screws 7. The tag antenna component 3 is fixed to the mounting surface formed by the three support screws 7 through three screws 5 and a gasket 6, and is connected to the conditioning circuit board component 2 through wires.

[0055] The pressure sensitive component 1 is composed of a nozzle 9, a flip-chip pressure core 10 and a conversion circuit board 11. The pressure chip is designed as a flip-chip structure by customizing the core shell and adopting leadless packaging technology. The pins 18 are directly sintered to the pads of the silicon piezoresistive chip 16 through solder, and the shell 17 is connected to the filter 15 by welding.

[0056] The conditioning circuit board assembly 2 is composed of a circuit board main board 12, a metal electromagnetic shielding cover 13 and a wire hole 14. The shielding cover is pressed against the circuit board main board 12 by three supporting screws 7 to form a metal shielding cavity, which can effectively protect against external electromagnetic interference. Two wire holes 14 are opened on the metal shielding cover. The conditioning circuit board 2 and the tag antenna assembly 3 are connected by wires. The wires are covered with shielding heat shrink tubing to enhance the anti-electromagnetic interference ability of the non-metallic end cap 4. The circuit board main board 12 includes a signal conditioning circuit, a linear voltage regulator circuit and a near-field communication circuit. The tire air inlet is connected to the sensor. When the tag antenna assembly 3 receives the electromagnetic field strength of the transmitting field, the near-field communication circuit on the circuit board main board 12 converts the alternating current signal into a voltage signal, and then powers the signal conditioning circuit and the communication circuit through the linear voltage regulator circuit. The signal conditioning circuit generates current excitation to power the pressure sensitive component 1. The pressure sensitive component 1 senses the pressure of the gas inside the tire and converts the pressure signal into a millivolt-level electrical signal. The electrical signal is compensated for the entire temperature range through the demodulation circuit component 2 and connected to the tag antenna component 3 to complete the demodulation and feedback of the near-field communication data, and output a non-contact digital signal proportional to the measured medium pressure and medium temperature.

[0057] The tag antenna assembly 3 is wired according to the special-shaped structure formed by the nozzle 9 and the support screw 7, and uses a printed circuit board FR-4 as a substrate, and is connected to the conditioning circuit board assembly 2 by wire welding.

[0058] The non-metallic end cap 4 is provided with an M27×1-6g internal thread and an O-ring groove, and is made of polyetheretherketone material, and has a built-in tag antenna component 3 to avoid shielding the field strength signal.

[0059] The O-ring 8 is installed in the O-ring groove of the non-metallic end cover 4 .

[0060] The nozzle 9 is provided with an M27×1-6H internal thread, and is made of stainless steel with a grade of 0Cr18Ni9. It is integrally fused and welded with the metal outer tube, adopts an integrated hexagonal structure, and is connected to the pressure core 10 by laser welding, and is screwed and connected to the non-metallic end cover 4 by threading, and a thread locking agent is applied to the connection; and is provided with an M12×1.5-6g external thread, which is connected to the aircraft tire as a mechanical interface, and an air inlet is designed at the front end. The air inlet and the pressure core 10 fixed to the nozzle 9 by welding form a pressure-sensing cavity, thereby transmitting the medium pressure to the pressure core 10 to realize pressure measurement.

[0061] The flip-chip pressure core 10 is composed of a filter 15, a silicon piezoresistive chip 16, a tube shell 17 and pins 18. The pins 18 are directly sintered to the pads of the silicon piezoresistive chip 16 by solder, and the tube shell 17 is laser welded to the filter 15 and then welded to the nozzle 1.

Claims

1. A passive NFC aircraft tire temperature and pressure composite sensor system, characterized in that: The system includes: a nozzle, a rear cover, a pressure core, a conversion circuit board, a conditioning circuit board assembly, and a tag antenna assembly; The nozzle is a two-stage step column; the small diameter end of the nozzle is provided with an air inlet hole, and the large diameter end is provided with a cavity; The pressure core is arranged in the air inlet; the pressure core is connected to the conversion circuit board; The conversion circuit board is connected to the conditioning circuit board assembly; The conditioning circuit board assembly is fixed to the step surface of the cavity at the large diameter end of the nozzle by means of supporting screws; The tag antenna assembly is mounted on the supporting screws by fixing screws; The rear cover is screwed onto the large diameter end of the nozzle; The small diameter end of the nozzle is connected to the tire through an external thread.

2. The system according to claim 1, characterized in that: The pressure core is welded and sealed to the air inlet hole, and the air inlet hole is connected to the interior of the tire to form a closed cavity.

3. The system according to claim 2, characterized in that: The pressure core includes: filter, silicon piezoresistive chip, tube shell and pins; The tube shell is a hollow cylinder with a flange at one end; The filter is welded to the end face of the tube shell without flange; The silicon piezoresistive chip is sealed and bonded to the step surface of the hollow cylinder; The pins are soldered to the pads of the silicon piezoresistive chip; The flange edge of the pipe shell is welded to the step surface of the air inlet hole of the pipe nozzle.

4. The system according to claim 3, characterized in that The conditioning circuit board components include: circuit board main board, metal electromagnetic shielding cover; The metal electromagnetic shielding cover is a cover-shaped structure with an open end, and three first threaded holes are opened on the end surface; Three second threaded holes are opened at corresponding positions on the main board of the circuit board; The supporting screws pass through the first and second threaded holes to fix the circuit board main board and the metal electromagnetic shielding cover on the step surface inside the large diameter end of the nozzle; The end surface of the metal electromagnetic shielding cover is provided with a threading hole.

5. The system according to claim 4, characterized in that An internal threaded hole is provided at the rear end of the support screw; The tag antenna assembly is screwed into the internal threaded hole at the rear end of the supporting screw through a fixing screw.

6. The system according to claim 5, characterized in that The rear cover is made of non-metallic material, and a sealing rubber ring is provided between the rear cover and the nozzle.

7. The system according to claim 6, characterized in that The conditioning circuit board component and the tag antenna component are connected through a wire, and a shielded heat shrink tubing is sleeved on the wire.

8. The structure according to claim 7, characterized in that The system works as follows: The handheld device is brought close to the system, and the tag antenna assembly receives the transmission field strength signal of the handheld device; The tag antenna component converts the transmission field strength signal into an AC signal; The conditioning circuit board assembly converts the AC signal into a stable DC signal to power the pressure core; The pressure core collects pressure signals; The conditioning circuit board assembly collects temperature data and compensates the pressure signal according to the temperature data; The compensated pressure and temperature data are sent to the handheld device via the tag antenna assembly.

Images