Temperature and pressure sensor and signal frame for communication of temperature and pressure sensor

Abstract

The present application provides a temperature and pressure sensor and a signal frame for communicating with the temperature and pressure sensor, relating to the technical field of automotive parts. The temperature and pressure sensor includes a circuit board assembly, a pressure sensing module, and a temperature sensing module. The pressure sensing module is connected to the circuit board assembly through a plug assembly, and the plug assembly and the pressure sensing module are respectively disposed on two surfaces of the circuit board assembly; the temperature sensing module is connected to the pressure sensing module through a metal shrapnel; wherein, the temperature sensing module is centrally disposed at the axial center position of the temperature and pressure sensor, and collects the temperature signal of the measured medium in a semi-exposed manner; the pressure sensing module is used to measure the pressure signal; the circuit board assembly is used to calibrate and process the temperature signal and the pressure signal and output them. The present application improves the timeliness and accuracy of medium measurement while avoiding the addition of wiring harnesses, and can also calibrate and process the signal in real time, improving the functionality of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive parts, and more particularly, to a temperature and pressure sensor and a signal frame for communicating with the temperature and pressure sensor. Background Art

[0002] With the development of automotive intelligence and energy conservation, it is necessary to integrate automotive pressure sensors and temperature sensors to collect temperature and pressure signals.

[0003] In the related art, the temperature and pressure sensor basically adopts a scheme of separately collecting and transmitting temperature and pressure. For example, on the basis of a single temperature signal, an additional temperature signal is added, and the ground wire of the pressure sensor is borrowed for the temperature signal. In addition, there is no "intersection" between temperature measurement and pressure measurement.

[0004] However, this method causes the sensor connector to change from 3 pins to 4 pins, and the wiring harness also needs to be increased accordingly. Moreover, the current scheme only separately collects temperature signals and pressure signals, cannot compensate for temperature drift, and cannot implement functions such as temperature diagnosis, resulting in poor user experience. Summary of the Invention

[0005] The purpose of the present invention is to provide a temperature and pressure sensor and a signal frame for communicating with the temperature and pressure sensor, which can improve the timeliness and accuracy of medium measurement while avoiding increasing the wiring harness, and can also perform calibration processing on signals in real time, improving the functionality of the device.

[0006] In a first aspect, the present invention provides a temperature and pressure sensor, which includes a circuit board assembly, a pressure sensing module, and a temperature sensing module. The pressure sensing module is connected to the circuit board assembly through a plug assembly, and the plug assembly and the pressure sensing module are respectively disposed on two sides of the circuit board assembly; the temperature sensing module is connected to the pressure sensing module through a metal shrapnel;

[0007] Wherein,

[0008] The temperature sensing module is centrally disposed at the axis position of the temperature and pressure sensor and collects the temperature signal of the measured medium in a semi-exposed manner;

[0009] The pressure sensing module is used to measure the pressure signal;

[0010] The circuit board assembly is used to calibrate and output the temperature signal and the pressure signal.

[0011] In an optional embodiment, it further includes: a housing that fixes the circuit board assembly, the pressure sensing module, and the temperature sensing module in a semi-closed manner; a threaded hole is provided at the bottom of the housing;

[0012] The temperature sensing module is a thermistor bracket assembly; the thermistor bracket assembly is inserted into the threaded hole at the bottom of the housing from inside the housing; the thermistor bracket assembly includes the metal shrapnel, plastic bracket, thermistor, and thermistor protection sleeve;

[0013] Wherein, the plastic bracket and the metal shrapnel are fixedly connected, the first end of the metal shrapnel connecting the plastic bracket passes through the plastic bracket and is connected to the thermistor; the second end of the metal shrapnel is a bent structure, and the end of the bent structure includes a contact point with a specified shape, and the contact point is connected to the connection electrode of the pressure sensing module.

[0014] In an alternative embodiment, the plastic bracket includes a first surface contacting the pressure sensing module and a second surface contacting the temperature sensing module;

[0015] A groove is provided on the first surface for installing an elastic gasket, a boss is provided on the second surface, and a spherical depression is provided on the boss;

[0016] Correspondingly, a diversion groove is provided at the first end of the thermistor protection sleeve; the depth of the diversion groove is set based on the position of the temperature sensing head of the thermistor; a spherical protrusion is provided at the second end of the thermistor protection sleeve and engages with the spherical depression on the second surface of the plastic bracket.

[0017] In an alternative embodiment, a specified number of rib structures are provided on the outer source of the thermistor protection sleeve, and the rib structures are rib structures with a specified draft angle.

[0018] In an alternative embodiment, the pressure sensing module is a ceramic capacitor; the ceramic capacitor includes a diaphragm, a metal electrode, a capacitor base, and a specified number of PIN pins connected in sequence;

[0019] Wherein, the metal electrode includes a measuring electrode and a connection electrode, and the metal electrode is connected to the PIN pin through conductive epoxy silver glue;

[0020] Funnel-shaped through holes with the same number as the PIN pins are provided on the capacitor base, and are connected to the PIN pins by injecting epoxy silver glue into the through holes.

[0021] In an alternative embodiment, a protection electrode surrounding the measuring electrode is further included; wherein, the inner diameter of the protection electrode ring and the gap of the measuring capacitor are not greater than 1 mm, and the outer diameter of the protection electrode ring is not greater than the radius of the sealed air cavity.

[0022] In an alternative embodiment, the circuit board assembly is a single-layer flexible circuit board assembly; the single-layer flexible circuit board assembly includes a signal acquisition module, a signal processing module, and a peripheral protection module;

[0023] Wherein,

[0024] The signal acquisition module is connected through the PIN pins connected to the ceramic capacitor by the wires and pads provided on the single-layer flexible circuit board assembly. Among them, the capacitance value of the ceramic capacitor is collected through 3 PIN pins, and the pressure value is calculated by the signal processing module; the resistance value of the thermistor is detected through another 2 PIN pins, and the temperature value is calculated by the signal processing module based on the resistance value;

[0025] The peripheral protection module includes at least an anti-reverse connection diode, a current-limiting resistor, a combined capacitor filter, and a TVS for electrical and EMC protection.

[0026] In an alternative embodiment, the circuit board assembly further includes a calibration microprocessor, which is used to calibrate the temperature signal and the pressure signal. Among them, the calibration process includes one or more of zero drift calibration, non-linear calibration, sensitivity calibration, and temperature compensation calibration.

[0027] In a second aspect, the present invention provides a signal frame for the communication of a temperature and pressure sensor. The signal frame includes a frame header and a response; the frame header includes an interval field, a synchronization field, and a PID field. The response includes 4 bytes, and the 4 bytes are used for pressure measurement, temperature measurement, pressure anomaly diagnosis, temperature anomaly diagnosis, checksum anomaly diagnosis, bit anomaly diagnosis, and upgrade operation through the division of specified bits.

[0028] In an alternative embodiment, the signal frame includes a first byte, a second byte, a third byte, and a fourth byte, and each byte includes 8 bits; wherein,

[0029] Bits 0 of the first byte to bit 2 of the second byte are used for pressure measurement; the range of the pressure measurement is 0 bar to 100 bar;

[0030] Bits 3 of the second byte to bit 3 of the third byte are used for temperature measurement; the range of the temperature measurement is -50 °C to 180 °C;

[0031] Bit 4 of the third byte is used for pressure anomaly diagnosis;

[0032] Bit 5 of the third byte is used for temperature anomaly diagnosis;

[0033] Bit 6 of the third byte is used for checksum anomaly diagnosis;

[0034] bit_7 of the third byte is used for bit exception diagnosis;

[0035] The fourth byte is used for hardware version upgrade and software version upgrade by setting specified bits.

[0036] The temperature and pressure sensor and the signal frame for communicating with the temperature and pressure sensor provided by the embodiment of the present invention. The temperature and pressure sensor includes a circuit board assembly, a pressure sensing module, and a temperature sensing module. The pressure sensing module is connected to the circuit board assembly through a plug assembly. The plug assembly and the pressure sensing module are respectively arranged on two surfaces of the circuit board assembly. The temperature sensing module is connected to the pressure sensing module through a metal shrapnel. Among them, the temperature sensing module is centrally arranged at the axis position of the temperature and pressure sensor and collects the temperature signal of the measured medium in a semi-exposed manner. The pressure sensing module is used to measure the pressure signal. The circuit board assembly is used to calibrate and output the temperature signal and the pressure signal. This method can directly contact the temperature sensing module with the measured medium by collecting the temperature signal of the measured medium in a semi-exposed manner, improving the timeliness of the medium measurement. At the same time, since the temperature sensor is located at the axis of the entire temperature and pressure sensor, the measurement accuracy is improved. Connecting the pressure sensing module to the circuit board assembly through the plug assembly avoids the problem of adding wiring harnesses. At the same time, by setting the circuit board assembly, the signal can be calibrated in real time, improving the functionality of the device.

[0037] Other features and advantages of the present invention will be described in the following specification, and in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structures specifically pointed out in the specification, claims, and drawings.

[0038] To make the above objectives, features, and advantages of the present invention more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, makes the following detailed description. Description of the Drawings

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 It is a structural diagram of a temperature and pressure sensor provided by an embodiment of the present invention;

[0041] Figure 2 It is a structural diagram of another temperature and pressure sensor provided by an embodiment of the present invention;

[0042] Figure 3 Structural diagram of a temperature sensing module provided by an embodiment of the present invention;

[0043] Figure 4 Structural diagram of a pressure sensing module provided by an embodiment of the present invention;

[0044] Figure 5 Structural diagram of a circuit board assembly provided by an embodiment of the present invention;

[0045] Figure 6 Structural diagram of a temperature and pressure sensor provided by an embodiment of the present invention.

[0046] Figure 7 Schematic diagram of a communication frame structure provided by an embodiment of the present invention.

[0047] Icons: 1 - Circuit board assembly; 2 - Pressure sensing module; 3 - Temperature sensing module; 4 - Plug assembly; 5 - Metal shrapnel; 6 - Housing; 7 - Threaded hole; 8 - Plastic bracket; 9 - Thermistor; 10 - Thermistor protection sleeve; 11 - Diaphragm; 12 - Capacitor base; 13 - Connecting electrode; 14 - Base electrode; 15 - Diaphragm electrode; 16 - Conductive epoxy silver glue; 17 - PIN pin; 18 - Ceramic capacitor; 19 - Thermistor bracket assembly; 20 - Sealing ring; 21 - Elastic gasket; 22 - Peripheral protection module; 23 - Flexible circuit one; 24 - Flexible circuit two; 25 - Thermistor connection pad; 26 - Plug assembly connection pad; 27 - Ceramic capacitor connection pad. Detailed implementation manners

[0048] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] At present, among the common temperature and pressure sensor design solutions on the market, the pressure measurement solutions include MEMS, ceramic resistors, ceramic capacitors, glass micro melting, sputtering thin films, etc. The MEMS solution cannot meet the requirements of 2 times the overload pressure and 3 times the burst pressure or higher; the ceramic resistor solution has a large temperature drift, and it is difficult to ensure consistency. It is difficult to achieve absolute pressure measurement, so it is also difficult to achieve low-cost mass production; glass micro melting and sputtering thin films are not sensitive to low pressure, and the process is complex and cannot achieve absolute pressure measurement and other disadvantages. Especially in the medium and low pressure section (<10 MPa), it is not an optimal solution; ceramic capacitors have become the preferred solution for medium and low pressure measurement due to advantages such as good dielectric compatibility, low cost, and excellent overload burst pressure resistance. However, how to "transmit" the temperature signal to the conditioning circuit through the ceramic capacitor is an industry problem.

[0050] Most of the current industry temperature measurement solutions choose the NTC thermistor solution. Compared with the PT platinum resistor solution, the NTC resistor is "good quality and low price". Due to the requirements of the temperature and pressure sensor seal, the solution selected in the industry is the injection molding solution of the thermistor and the protective shell. The advantage of this solution is that the thermistor can be sealed and protected, and at the same time, it is easy to meet the sealing requirements of the temperature and pressure sensor assembly. However, this solution also brings a problem, that is, the response time of the temperature sensor will be very long, and it is difficult to meet the requirements of short measurement response time. For example, for a plastic-coated thermistor, t63 may reach 15 s. Even if a brass shell with good thermal conductivity and a thermally conductive silicone grease injection solution is used, it still takes 5 s. If the thermistor can be exposed, the response time can be increased to 2 s. Although exposing the thermistor improves the response time, it also brings problems. How to protect the thermistor from external damage and how to achieve the seal of the sensor assembly have become new problems.

[0051] Compared with traditional single-temperature and single-pressure sensors, the temperature and pressure integrated solution also needs to solve the problem of integrated transmission of temperature signals and pressure signals. In related technologies, there are already solutions for separate transmission of temperature and pressure. This solution is equivalent to adding a temperature signal on the basis of a single temperature signal. The temperature signal borrows the ground wire of the pressure sensor. In addition, there is no "intersection" between temperature measurement and pressure measurement. This solution has a simple principle, but it also brings problems. First, the connector needs to change from 3 pins to 4 pins, and the wire harness also needs to be increased synchronously. It is impossible to compensate for the temperature drift and impossible to implement functions such as temperature diagnosis. Therefore, how to achieve signal integration, processing, and diagnosis is also an urgent problem for temperature and pressure sensors. Based on this, an embodiment of the present invention provides a temperature and pressure sensor and a signal frame for communicating with the temperature and pressure sensor to at least partially solve the deficiencies in the related technical solutions.

[0052] For the convenience of understanding this embodiment, first, a temperature and pressure sensor disclosed in an embodiment of the present invention will be introduced in detail. See Figure 1As shown, the temperature and pressure sensor includes a circuit board assembly 1, a pressure sensing module 2, and a temperature sensing module 3. Among them, the pressure sensing module 2 is connected to the circuit board assembly 1 through a plug assembly 4. The plug assembly 4 and the pressure sensing module 2 are respectively arranged on two sides of the circuit board assembly 1. The plug assembly is a plug assembly with PIN pins; the temperature sensing module 3 is connected to the pressure sensing module 2 through a metal shrapnel 5.

[0053] The above temperature sensing module 3 is centrally arranged at the axial center position of the temperature and pressure sensor, and adopts a semi-exposed method to collect the temperature signal of the measured medium. This semi-exposed method means that the part below the temperature sensor extends out of the housing 6 and directly contacts the measured medium. See Figure 2 shown. Figure 2 In 6, the housing 6 is used to fix the circuit board assembly 1, the pressure sensing module 2, and the temperature sensing module 3 in a semi-closed manner. A threaded hole 7 is provided at the bottom of the housing 6. Due to the provision of this threaded hole 7, the temperature sensing module 3 adopts a semi-exposed method to contact the measurement environment. In one embodiment, the threaded hole 7 can be centrally arranged, which also ensures the central property of the temperature sensing module 3.

[0054] The above pressure sensing module 2 is used to measure the pressure signal, and because it is connected to the circuit board assembly 1, the measured pressure signal is transmitted to the circuit board assembly 1.

[0055] The above circuit board assembly 1 is used to calibrate and output the temperature signal and the pressure signal.

[0056] Next, the specific structure of this temperature and pressure sensor will be described in detail.

[0057] In one embodiment, the above temperature sensing module 3 is a thermistor 9 bracket assembly. The thermistor 9 bracket assembly is inserted into the threaded hole 7 at the bottom of the housing 6 from the inside of the housing 6. See Figure 3 shown. The thermistor 9 bracket assembly includes a metal shrapnel 5, a plastic bracket 8, a thermistor 9, and a thermistor protection sleeve 10.

[0058] The above plastic bracket 8 and the metal shrapnel 5 are fixedly connected. For example, the plastic bracket 8 and the metal shrapnel 5 can be injection-molded together through an injection molding process. The first end of the metal shrapnel 5 connecting the plastic bracket 8 passes through the plastic bracket 8 and is connected to the thermistor 9. The first end of the metal shrapnel 5 connecting the thermistor 9 is provided with a thermistor 9 positioning structure and a welding structure. In actual production, the thermistor 9 can be first placed in the positioning structure, and then the pins of the thermistor 9 are connected to the welding structure of the hot metal shrapnel 5 through brazing or resistance welding. The second end of the metal shrapnel 5 is a bent structure, and the end of the bent structure includes a contact point with a specified shape (such as circular, square, etc.). The contact point is connected to the connection electrode 13 of the pressure sensing module 2.

[0059] In one embodiment of the above-mentioned plastic bracket 8, two elliptical diversion holes may be symmetrically arranged at both ends of the metal elastic sheet 5, so as to enable the medium to enter and exit quickly.

[0060] In an alternative embodiment, the plastic bracket 8 includes a first surface in contact with the pressure sensing module 2 and a second surface in contact with the temperature sensing module 3;

[0061] A groove is provided on the first surface for installing the elastic gasket 21, and a boss is provided on the second surface with a spherical depression provided thereon; in the above manner, by providing an extended boss on the second surface with a spherical depression provided thereon, and an elastic gasket groove is provided in the first surface for installing the elastic gasket, the installed elastic gasket is located below the metal elastic sheet 5. After riveting is completed, the elastic gasket can firmly support the thermosensitive metal elastic sheet 5 to ensure the connection reliability with the ceramic capacitor electrode.

[0062] Correspondingly, a diversion groove is provided at the first end of the thermistor protection sleeve 10; the groove depth of the diversion groove is set based on the position of the temperature sensing head of the thermistor 9; a spherical protrusion is provided at the second end of the thermistor protection sleeve 10 to engage with the spherical depression on the second surface of the plastic bracket 8. In one embodiment, a "cross"-shaped diversion groove is provided at one end (i.e., the above-mentioned first end) of the thermistor 9 protection sleeve, and the groove depth should just expose the temperature sensing head of the thermistor 9 after being installed in place. At the other end (i.e., the above-mentioned second end), a "one"-shaped slot is used, and a spherical protrusion is provided inside for mating with the spherical depression of the extended protrusion on the surface 1 of the plastic bracket 8.

[0063] Preferably, a specified number of rib structures are provided on the outer source of the thermistor protection sleeve 10, and the rib structures are rib structures with a specified draft angle. In practical applications, 4 "rib" structures can be provided on the outer circle of the thermistor protection sleeve 10, and the "rib" structures have a certain draft angle. When it is inserted into the threaded hole 7 of the housing 6, it is gradually tightened, and when the assembly is in place, the thermistor 9 protection sleeve can be fixed to the plastic bracket 8.

[0064] See Figure 4As shown in the figure, the above-mentioned pressure sensing module 2 is a ceramic capacitor. The ceramic capacitor includes a diaphragm 11, a metal electrode, a capacitor base 12, and a specified number of PIN pins 17 connected in sequence. Among them, the metal electrode includes a measuring electrode and a connecting electrode 13, and the measuring electrode includes a base electrode 14 and a diaphragm electrode 15. Among them, the metal electrodes (i.e., the connecting electrode 13, the base electrode 14, and the diaphragm electrode 15) are connected to the PIN pins 17 through conductive epoxy silver glue 16. The connecting electrode 13 is a conductive electrode printed and sintered on the ceramic capacitor base 12, which is connected to the PIN pins 17 of the ceramic capacitor through epoxy conductive silver glue, and this connecting electrode 13 can also be connected to the metal spring piece 5 of the thermistor 9 bracket assembly, so as to obtain the signal of the thermistor 9 through this connecting electrode 13.

[0065] In specific implementation, the thickness of the capacitor base 12 should ensure no deformation after applying the full-scale pressure, and its thickness is 2 - 6 mm. The plate metal electrodes and their pads are made by screen printing or vacuum sputtering process, and the thickness of the final electrode < 1.5 μm.

[0066] When pressure P is applied to the ceramic capacitor, the measured capacitance value of the ceramic capacitor is C 1 = C 0 + ΔC, where C 0 is the initial capacitance value, that is ΔC is the capacitance change amount caused by applying pressure P, and its calculation formula is where in the formula, L is the radius of the sealed air cavity, P is the applied pressure, u is the Poisson's ratio of the diaphragm, E is the Young's modulus of the diaphragm, h is the thickness of the diaphragm. a is the radius of the measuring electrode, d is the initial distance between the measuring capacitance electrodes, ε 0 is the vacuum permittivity, and ε r is the relative permittivity of air.

[0067] The setting of the measuring electrode size should consider the capacitance change amount and change rate. The radius a of the measuring electrode is generally set to 0.5 - 0.6L (L is the radius of the sealed air cavity).

[0068] The set value of the protection capacitor C2 is approximately equal to the initial value C0 of the measuring capacitor, that is C 2 ≈ C 0 .

[0069] The protection electrode and the reference electrode are generally made by printing and sintering gold paste, and their thickness is uniform, generally required to be less than 1.5um.

[0070] There is an electrostatic field between the capacitor plates of the capacitive sensor. Due to the existence of the edge effect of the plates, the electric field distribution at the edges is uneven, resulting in the edge effect of the capacitance. This is equivalent to connecting an additional capacitor in parallel with the capacitance of the sensor. The edge effect not only reduces the sensitivity of the capacitive sensor but also causes non-linearity. In an optional embodiment, a protection electrode surrounding the measurement electrode is further included, that is, an equipotential ring is added in the structure. Among them, the inner diameter of the protection electrode ring is close to the radius of the measurement capacitance, and the gap between the inner diameter of the protection electrode ring and the measurement capacitance is not greater than 1 mm, and the outer diameter of the protection electrode ring is not greater than the radius of the sealed air cavity. The protection electrode and the protected electrode have the same potential, so that the entire area of the working plate is within the range of a uniform electric field.

[0071] The diaphragm and base materials of the ceramic capacitor are selected as 96% alumina ceramic, the glass glue is a slurry containing glass rods, the electrodes generally use gold material, the PIN pins use copper-tin alloy or copper-zinc alloy, and are plated with nickel first and then tin or silver or copper.

[0072] The shape of the diaphragm of the capacitor is circular, including a positioning structure with a circular notch, which is used to ensure the printing accuracy of the electrodes and the positioning accuracy of the lamination and sintering. The thickness is determined according to the full-scale capacitance change ΔC, ensuring that the capacitance change ΔC corresponding to the deformation amount Δd of the diaphragm after applying the full-scale pressure at this thickness meets the input requirements of the matching chip. The diaphragm thickness is generally 0.4 - 0.7 mm. The metal electrodes of the plates and their pads are made by screen printing or vacuum sputtering process, and the thickness of the final electrode is <1.5 μm. At the same time, the diaphragm is provided with two oval openings, whose function is to expose two connecting electrodes, and the connecting electrodes can be connected to the metal elastic pieces of the thermistor bracket assembly.

[0073] In one embodiment, the specified number of PIN pins can be 5. Among them, 3 PIN pins are used to connect the detection pressure measurement electrode (including the protection electrode surrounding the measurement electrode), and the other two are connecting electrodes, which are used to connect the thermistor electrodes at the bottom.

[0074] Furthermore, funnel-shaped through holes with the same number as the PIN pins can be provided on the capacitor base. By injecting epoxy silver glue into the through holes to connect with the PIN pins, and by injecting epoxy silver glue into the holes and then inserting the PIN pins, metal conductivity can be achieved.

[0075] The shape of the capacitor base is circular and also includes a circular notch positioning structure, which is used to ensure the printing accuracy of the electrodes and glass glue and the positioning accuracy of lamination and sintering. There are 5 funnel-shaped holes penetrating the base. Epoxy silver glue can be injected into the holes, and then PIN pins are inserted to achieve metal conductivity. The thickness of the base should ensure no deformation after applying the full-scale pressure, and its thickness is 2 - 6 mm. The metal electrodes of the electrode plate and their pads are made by screen printing or vacuum sputtering process, and the thickness of the final electrode is < 1.5 μm.

[0076] The shape of the glass glue is circular ring, and the peripheral of the ring includes a hollow structure, which is used to accommodate the excess glass paste. At the same time, it is hollowed and sealed at the connection electrode of the thermistor. When connected to the metal elastic sheet of the thermistor support assembly, it prevents the medium from entering both ends of the capacitor side of the ceramic capacitor and avoids the failure of the ceramic capacitor. The thickness is determined according to the capacitance value C0 of the initial capacitor, and it is ensured that the capacitance value C0 of the initial capacitor meets the input requirements of the matching chip at this thickness, and its thickness is 15 - 50 μm.

[0077] This embodiment provides a production process of a ceramic capacitor, including: diaphragm and base production and cleaning, electrode printing, electrode sintering, electrode grinding and cleaning, glass glue printing and sintering, lamination and sintering, PIN pin dispensing and sintering, testing and leak detection.

[0078] In the diaphragm and base production and cleaning process, the diaphragm and base are made by the tape casting process, and then cleaned to ensure the cleanliness of the product and avoid defects caused by introducing impurities.

[0079] In the electrode printing and sintering process, the printing dimension accuracy of the electrodes should be ensured to meet the set requirements.

[0080] The grinding and cleaning process ensures that the roughness and flatness of the product meet the set requirements and avoid defects in subsequent processes.

[0081] In the glass glue printing and sintering process, it is necessary to ensure that the glass thickness and weight meet the requirements, and there are no defects such as incorrect printing position and deviation.

[0082] In the lamination and sintering process, the positioning and orientation accuracy of the relative positions of the diaphragm base is ensured through positioning settings. The gap is ensured by the glass gasket in the glass paste. The softening temperature of the gasket is higher than the sintering temperature. The sintering temperature is 800℃ - 900℃, and water cooling is used for cooling.

[0083] In the PIN pin dispensing and sintering process, a reliable electrical connection between the inserted pin and the electrode should be ensured.

[0084] The testing and leak detection process is used to ensure that the product performance meets the requirements and there are no defects such as capacitor drift.

[0085] Further, refer to Figure 5As shown, the above circuit board assembly is a single-layer flexible circuit board assembly, including flexible circuit one 23 and flexible circuit two 24, which can reduce the parasitic capacitance effect and has the characteristics of flexibility and bendability. Electronic components are soldered onto the flexible circuit board through SMT technology. The single-layer flexible circuit board assembly includes a signal acquisition module, a signal processing module, and a peripheral protection module. The signal acquisition module is connected to the PIN pins of the ceramic capacitor 18 through the wires and pads arranged on the single-layer flexible circuit board assembly. Among them, the capacitance value of the ceramic capacitor is collected through 3 PIN pins, and the pressure value is calculated by the signal processing module; the resistance value of the thermistor is detected through another 2 PIN pins, and the temperature value is calculated based on the resistance value by the signal processing module.

[0086] The pads on the circuit board assembly include a thermistor connection pad 25, a plug assembly connection pad 26, and a ceramic capacitor connection pad 27, as shown in Figure 5 shown.

[0087] In an alternative embodiment, the circuit board assembly further includes a calibration microprocessor for calibrating the temperature signal and the pressure signal. Among them, the calibration process includes one or more of zero drift calibration, non-linear calibration, sensitivity calibration, and temperature compensation calibration.

[0088] In a specific embodiment, the signal acquisition module is connected to 5 PIN pins of the ceramic capacitor through flexible circuit board wires and pads. Among them, 3 PINs are used to detect the change of capacitance to measure pressure, and the other 2 PINs are used to detect the change of the resistance value of the thermistor to measure the temperature change. The signal processing module includes two parts: a pressure processing channel and a temperature processing channel. The pressure processing channel includes a capacitance excitation generator, a conversion circuit for detecting and converting capacitance into voltage, and a 24-bit analog-to-digital converter; the temperature channel includes a data selector and a 24-bit analog-to-digital converter. The digital temperature and pressure signals after analog-to-digital conversion enter the calibration microprocessor, and the calibration microprocessor performs zero drift calibration, non-linear calibration, sensitivity calibration, and temperature compensation calibration on the temperature and pressure signals. At the same time, it can also adjust the zero point and perform range scaling according to customer requirements.

[0089] In addition, the calibrated data is sent to the LIN transceiver, and the LIN transceiver outputs signals according to the LIN protocol. At the same time, the signal processing module also includes necessary power management modules, storage modules, oscillation circuits, and diagnostic modules.

[0090] The above peripheral protection module 22 includes at least an anti-reverse connection diode, a current limiting resistor, a combined capacitor filter, and a TVS for electrical and EMC protection.

[0091] The temperature and pressure sensor provided in this embodiment, as shown in Figure 6As shown, the external part 6 is a housing made of metal structure. Generally, the material is selected from aluminum alloy, ferroalloy with coating or copper alloy. To reduce weight and cost, aluminum alloy is mostly chosen at present except for special medium requirements, such as aluminum alloys like 6005-T5 or 6061-T6. The outside of the metal housing is set in a hexagonal shape of HEX24, which can be installed with the cooperation of an installation wrench. Threads for installation are provided at the bottom to achieve threaded connection with the customer's mounting base. Such a mounting base can include, for example, a mounting base set on the air-conditioning refrigerant, pipeline, pump or valve, and can be installed by screwing on with the corresponding threads. Due to the compact setting of this sensor, M12 threads can be used for the threads, reducing the volume of the mounting base and enabling it to be installed in positions with smaller spaces such as pipelines. The thermistor support assembly is inserted into the threaded hole of the metal housing from the inside of the housing. Since the threaded hole is a through hole, the thermistor support assembly 19 is also exposed to the measurement environment. The threaded hole is centered, which also ensures the centering property of the thermistor. The thermistor support assembly is connected to the connection electrode of the ceramic capacitor at its upper end through a metal shrapnel. The connection electrode is a conductive electrode printed and sintered on the ceramic capacitor base, and it is connected to the PIN pin of the ceramic capacitor through epoxy conductive silver glue. In addition to having the connection electrode for the thermistor, a pair of pressure measurement electrodes are also printed and sintered on the diaphragm and base of the ceramic capacitor, which form a pressure measurement channel. Finally, all the electrodes are welded to the circuit board assembly through ceramic PIN pins. There is a dedicated conditioning chip on the circuit board assembly, and peripheral circuits for electrical protection and EMC protection are also provided around the conditioning chip. The other end of the circuit board assembly is welded to the plug assembly through pads. In addition, a sealing ring 20 is provided between the housing and the ceramic capacitor. The sealing ring can be made of different materials according to different media. Its main function is to isolate the inside of the sensor from the medium, preventing medium leakage and electrical failure of the sensor. The ceramic capacitor is provided with a positioning notch, and the plug assembly is provided with a positioning protrusion. During the assembly of the assembly, after the plug assembly is positioned and matched with the ceramic capacitor, it is installed into the housing with the sealing ring and the temperature sensor support assembly installed, and becomes an integral whole by riveting the metal housing. Sealing silicone is applied at the flanging of the riveting to prevent the inside of the sensor from contacting the external environment and avoid electrical failure. Therefore, the temperature response time of this temperature and pressure sensor is faster, the structure is more compact, and the communication is more convenient (LIN bus single-wire transmission of temperature and pressure signals).

[0092] After the temperature signal and pressure signal are collected by adopting the above structure, the signal can be further transmitted through communication with a LIN receiver. This embodiment provides a signal frame for the communication of the temperature and pressure sensor. The signal frame includes a frame header and a response; the frame header includes an interval field, a synchronization field and a PID field, which conform to the LIN standard specification. The response includes 4 bytes, and the 4 bytes are used for pressure measurement, temperature measurement, pressure anomaly diagnosis, temperature anomaly diagnosis, checksum anomaly diagnosis, bit anomaly diagnosis and upgrade operation through the division of specified bits.

[0093] In an alternative embodiment, referring to Figure 7 as shown, the above signal frame includes a first byte Byte1, a second byte Byte2, a third byte Byte3, and a fourth byte Byte4, and each byte includes 8 bits (bit0-bit7). Among them:

[0094] Bit_0 of the first byte to bit_2 of the second byte are used for pressure measurement, and the pressure measurement range is 0 bar to 100 bar.

[0095] Bit_3 of the second byte to bit_3 of the third byte are used for temperature measurement; the temperature measurement range is -50°C to 180°C.

[0096] Bit_4 of the third byte is used for pressure anomaly diagnosis; bit_5 of the third byte is used for temperature anomaly diagnosis; bit_6 of the third byte is used for checksum anomaly diagnosis; bit_7 of the third byte is used for bit anomaly diagnosis; these 4 bits (i.e., bit4-bit7 of the third byte) are combined together to construct the first diagnosis method of the LIN sensor, that is, the diagnostic bit diagnosis of the signal frame.

[0097] The fourth byte is used for hardware version upgrade and software version upgrade by setting specified bits. The hardware version can start from Byte_4, bit_0, with a total of 4 bits, and can achieve an upgrade of the hardware version from 0 to 15. The software version can start from Byte_4, bit_4, with a total of 4 bits, and can achieve an upgrade of the software version from 0 to 15.

[0098] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0099] When the above-mentioned functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0100] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0101] Finally, it should be noted that the above embodiments are only specific implementation manners of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or make equivalent replacements for some of the technical features; and these modifications, changes, or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A temperature and pressure sensor, characterized in that, the temperature and pressure sensor includes a circuit board assembly, a pressure sensing module and a temperature sensing module, and further includes: a housing that fixes the circuit board assembly, the pressure sensing module and the temperature sensing module in a semi-closed manner, and a threaded hole is provided at the bottom of the housing; the pressure sensing module is connected to the circuit board assembly through a plug assembly, and the plug assembly and the pressure sensing module are respectively arranged on two surfaces of the circuit board assembly; the temperature sensing module is connected to the pressure sensing module through a metal shrapnel; wherein, the temperature sensing module is centrally arranged at the axis position of the temperature and pressure sensor and collects the temperature signal of the measured medium in a semi-exposed manner; the pressure sensing module is used to measure the pressure signal; the circuit board assembly is used to calibrate and output the temperature signal and the pressure signal; the temperature sensing module is a thermistor bracket assembly; the thermistor bracket assembly is inserted into the threaded hole at the bottom of the housing from the inside of the housing; the thermistor bracket assembly includes the metal shrapnel, a plastic bracket, a thermistor and a thermistor protection sleeve; wherein, the plastic bracket and the metal shrapnel are fixedly connected, and the first end of the metal shrapnel connecting the plastic bracket passes through the plastic bracket and is connected to the thermistor; the second end of the metal shrapnel is a bent structure, and the end of the bent structure includes a contact point with a specified shape, and the contact point is connected to the connection electrode of the pressure sensing module; two elliptical diversion holes are symmetrically arranged at both ends of the metal shrapnel to realize the rapid entry and exit of the medium; the plastic bracket includes a first surface contacting the pressure sensing module and a second surface contacting the temperature sensing module; a groove is provided on the first surface, and the groove is used to install an elastic gasket, and a boss is provided on the second surface, and a spherical depression is provided on the boss; correspondingly, a diversion groove is provided at the first end of the thermistor protection sleeve; the groove depth of the diversion groove is set based on the position of the temperature sensing head of the thermistor; a spherical protrusion is provided at the second end of the thermistor protection sleeve and is engaged with the spherical depression on the second surface of the plastic bracket; the pressure sensing module is a ceramic capacitor; the ceramic capacitor includes a diaphragm, a metal electrode, a capacitor base and PIN pins with specified data connected in sequence; wherein, the metal electrode includes a measuring electrode and a connection electrode, and further includes a protection electrode surrounding the measuring electrode; the metal electrode is connected to the PIN pins through conductive epoxy silver glue; funnel-shaped through holes with the same number as the PIN pins are provided on the capacitor base, and are connected to the PIN pins by injecting epoxy silver glue into the through holes; The circuit board assembly is a single-layer flexible circuit board assembly; the single-layer flexible circuit board assembly includes a signal acquisition module, a signal processing module, and a peripheral protection module; wherein, the signal acquisition module is connected to the PIN pins connecting the ceramic capacitor through the wires and pads provided on the single-layer flexible circuit board assembly. Among them, the capacitance value of the ceramic capacitor is acquired through 3 PIN pins, and the pressure value is calculated by the signal processing module; the resistance value of the thermistor is detected through another 2 PIN pins, and the temperature value is calculated by the signal processing module based on the resistance value. The circuit board assembly further includes a calibration microprocessor, which is used for calibrating temperature signals and pressure signals.

2. The temperature and pressure sensor according to claim 1, wherein, A specified number of rib structures are provided on the outer source of the thermistor protection sleeve, and the rib structures are rib structures with a specified draft angle.

3. The temperature and pressure sensor according to claim 1, wherein, The inner diameter of the protective electrode ring and the gap of the measured capacitor are not greater than 1 mm, and the outer diameter of the protective electrode ring is not greater than the radius of the sealed air cavity.

4. The temperature and pressure sensor according to claim 1, wherein, The peripheral protection module at least includes an anti-reverse connection diode, a current limiting resistor, a combined capacitor filter, and a TVS for electrical and EMC protection.

5. The temperature and pressure sensor according to claim 1, wherein, The calibration process includes one or more of zero drift calibration, non-linear calibration, sensitivity calibration, and temperature compensation calibration.

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