Three-parameter combination transmitter adopting micro-pressure mode for measurement

Abstract

The invention relates to the technical field of transmitters, in particular to a three-parameter combination transmitter adopting a micro-pressure mode for measurement, which comprises a transmitter shell and a measuring rod which are in threaded connection, and a micro-pressure piezoresistive sensor is arranged at the bottom end of the inner side surface of the measuring rod. The micro-pressure piezoresistive sensor comprises a silicon wafer and four high-precision semiconductor strain gauges and forms a Wheatstone bridge. A micro-pressure piezoresistive sensor circuit of the micro-pressure piezoresistive sensor comprises a slide rheostat R1, a slide rheostat R2, a slide rheostat R3 and a slide rheostat R4. The resistance wire is arranged in the measuring rod, the height of the resistance wire should be larger than the measuring range of the oil level, the micro-pressure piezoresistive sensor chip and the high-precision silicon pressure chip are selected, tiny pressure change can be measured through fine signal conditioning, the pressure change can be taken out to represent the change of the oil level, and the oil level sensor is obliquely arranged, so that the oil level can be accurately measured. Measurement of the oil level height is not affected, and the measured oil level height is a real oil level.

Description

Technical Field

[0001] The invention relates to a three-parameter combination transmitter, in particular to a three-parameter combination transmitter adopting a micro-pressure measurement method, and belongs to the technical field of transmitters. Background Art

[0002] In response to the problems that the accuracy error of the existing three-parameter combination transmitter becomes larger during long-term operation and is often damaged due to improper operation during use, the existing manufacturers mainly use resistance wire heating, and the resistance value change of the resistance wire in different media is used to measure the oil level. When the oil level sensor is installed vertically, the measured oil level should be accurate, but if the oil level sensor is installed at an angle, the measured oil level has a large error, and the true oil level needs to be calculated. Moreover, when the oil level sensor is in an oil-deficient state, it is easy to overheat and be damaged due to the long-term dry burning of the resistance wire. Therefore, many users feel that the oil level sensor in this type of three-parameter combination transmitter is relatively easy to be damaged. Even if the oil level sensor is not damaged, due to long-term use, the adhesion of oil scale on the oil level sensor will also cause large errors in oil level measurement, and regular cleaning is required to resume normal use.

[0003] Some manufacturers use capacitive measurement principles to measure oil levels. However, the capacitive measurement principle has a very large range of liquid levels, and the accuracy of small-range liquid level measurements is extremely poor. In addition, the capacitive level measurement circuit is greatly affected by the medium, easily affected by position and spacing changes, and has extremely high requirements for installation and maintenance. Therefore, it is not suitable for small-range oil level measurement.

[0004] Therefore, it is urgent to improve the three-parameter combination transmitter to solve the above-mentioned problems. Summary of the invention

[0005] The purpose of the present invention is to provide a three-parameter combination transmitter that uses a micro-pressure measurement method. The resistance wire is placed inside the measuring rod, and the height should be greater than the measuring range of the oil level. A micro-pressure piezoresistive sensor chip and a high-precision silicon pressure chip are selected. After fine signal conditioning, extremely small pressure changes can be measured. This pressure change can be taken out to represent the change in oil level. Moreover, the oil level sensor is placed at an angle, which will not affect the measurement of the oil level height. The measured oil level height is the actual oil level.

[0006] In order to achieve the above object, the main technical solutions adopted by the present invention include: A three-parameter combination transmitter adopting micro-pressure measurement comprises a transmitter housing and a measuring rod connected by threads, wherein a micro-pressure piezoresistive sensor is fixedly arranged at the bottom end of the inner side of the measuring rod; A signal processing circuit is fixedly arranged inside the transmitter housing, and the micro-pressure piezoresistive sensor establishes a communication connection with the signal processing circuit; The micro-pressure piezoresistive sensor includes a silicon wafer and four high-precision semiconductor strain gauges to form a Wheatstone bridge. Glass layers are fixedly arranged on the upper and lower sides of the silicon wafer. A vacuum cavity is established in the middle of the silicon wafer, wherein the pressure enters the sensor vacuum cavity through the pressure induction cavity. The stress silicon film will bulge slightly upward due to the influence of external force and undergo elastic deformation. The resistance of the four high-precision semiconductor strain gauges will change, destroying the balance of the Wheatstone bridge circuit. The Wheatstone bridge will output a voltage signal proportional to the pressure and transmit it to the signal processing circuit. It has the advantages of high sensitivity, good linearity and high stability. The micro-pressure piezoresistive sensor circuit of the micro-pressure piezoresistive sensor comprises a sliding rheostat R1, a sliding rheostat R2, a sliding rheostat R3 and a sliding rheostat R4, wherein the sliding rheostat R1 and the sliding rheostat R2 are connected in series and then connected to a resistor R8 and a resistor R9, and connected to a reference voltage REF through a resistor R10; The sliding rheostat R3 and the sliding rheostat R4 are connected in series, connected to a resistor R11, and electrically connected to a common contact COM; A positive output voltage is connected between the sliding rheostat R1 and the sliding rheostat R2, and a negative output voltage is connected between the sliding rheostat R3 and the sliding rheostat R4.

[0007] Preferably, the sliding rheostat R1 and the sliding rheostat R3 are connected in parallel to a resistor R7, and a resistor R5 and a resistor R6 are arranged in series between the resistor R7 and the positive output voltage.

[0008] Preferably, the signal processing circuit is provided with a chip IC1, and the reference voltage REF on the resistor R10 is electrically connected to the pin 3 of the chip IC1; The positive output voltage is electrically connected to pin 6 of the chip IC1, and the negative output voltage is electrically connected to pin 5 of the chip IC1; A resistor R13 is electrically connected to the pin 9 of the chip IC1 , and a common contact COM on the resistor R11 is electrically connected between the pin and the resistor R13 .

[0009] Preferably, a resistor R17 and a capacitor C1 are arranged in parallel with the resistor R13, a transistor Q1 is electrically connected to the capacitor C1, a resistor R12 is arranged in parallel with the transistor Q1, and the transistor Q1 and the resistor R12 are electrically connected to the pin 1 of the chip IC1 after being connected in parallel; The front end of the resistor R17 is connected to the transistor Q2 via the resistor R16, and the base of the transistor Q2 is electrically connected to the pin 13 of the chip IC1 via the resistor R15; A capacitor C5 is connected in parallel between the base of the transistor Q2 and the emitter of the transistor Q2; The collector of the transistor Q2 is electrically connected to the collector of the transistor Q1; A capacitor C3 is electrically connected between the collectors of the transistor Q2 , and the capacitor C3 is electrically connected to the pin 14 of the chip IC1 through a resistor R14 .

[0010] Preferably, a diode D1 is electrically connected to pin 2 of the chip IC1, and the diode D1 is electrically connected to the resistor R12 through the capacitor C6 and then outputs; The pin 15 of the chip IC1 is electrically connected to a capacitor C2 and is grounded.

[0011] Preferably, a vibration sensor is fixedly arranged inside the transmitter housing just below the signal processing circuit, and the vibration sensor is electrically connected to the signal processing circuit; A power processing circuit is fixedly arranged inside the transmitter housing above the signal processing circuit, and a signal shielding cable is electrically connected to the power processing circuit. The signal shielding cable is fixedly arranged on the upper side of the transmitter housing.

[0012] Preferably, a temperature sensor is fixedly arranged inside the measuring rod above the micro-pressure piezoresistive sensor, and the temperature sensor establishes a communication connection with the signal processing circuit.

[0013] Preferably, a ventilation hole is provided on the measuring rod, and a ventilation valve is fixedly arranged inside the ventilation hole.

[0014] Preferably, the ventilation valve comprises an exhaust cylinder and an air storage bag, the exhaust cylinder is provided with an exhaust cylinder thread connected with the air vent by a thread, the exhaust cylinder is provided with an exhaust cylinder air inlet hole, a sealing plate slide groove is provided inside the exhaust cylinder air inlet hole, a sealing plate is slidably provided inside the sealing plate slide groove, the air storage bag is filled with carbon dioxide gas, a push rod bin is fixedly provided on one side of the air storage bag, a sealing plate piston push rod corresponding to the push rod bin is provided on the sealing plate, and the sealing plate piston push rod is slidably provided inside the push rod bin; A filter screen is fixedly arranged at the port of the exhaust pipe.

[0015] Preferably, a threaded joint is provided at the upper end of the measuring rod, a connecting nut corresponding to the threaded joint is provided at the bottom of the transmitter housing, and the connecting nut is connected to the threaded joint by threaded engagement; The bottom of the measuring rod is connected with a sensor protection cover.

[0016] The present invention has at least the following beneficial effects: 1. Four high-precision semiconductor strain gauges form a Wheatstone bridge. Glass layers are fixed on the upper and lower sides of the silicon wafer. A vacuum chamber is established in the middle of the silicon wafer. The pressure enters the sensor vacuum chamber through the pressure induction chamber. The stress silicon film will bulge slightly upward due to the influence of external force and undergo elastic deformation. The resistance of the four high-precision semiconductor strain gauges changes, destroying the balance of the Wheatstone bridge circuit. The Wheatstone bridge will output a voltage signal proportional to the pressure and transmit it to the signal processing circuit 4. The measurement accuracy of this signal can reach 0.01%~0.03%FS, with the advantages of high sensitivity, good linearity and high stability.

[0017] 2. The vibration measurement part mainly uses vibration sensors to measure the vibration of machinery and equipment, and transmits the data to the signal processing circuit for processing and analysis. The temperature measurement part uses temperature sensors to measure the temperature changes of machinery and equipment, and provides real-time temperature data, which is convenient for users to detect the thermal operation of machinery and equipment. The oil level measurement part uses a micro-pressure piezoresistive sensor to measure the oil level in the machinery and equipment, and transmits real-time oil level data to the signal processing circuit. It can be connected with a variety of general secondary instruments to realize single equipment monitoring, and can also be connected with a computer data acquisition monitoring system.

[0018] 3. Use micro-pressure piezoresistive sensor chips and high-precision silicon pressure chips. After fine signal conditioning, they can measure extremely small pressure changes, usually 0~0.5KPa. If this pressure change is taken out, it can be represented as a change in the oil level. This circuit also has an obvious advantage, that is, the oil level sensor is placed at an angle, which will not affect the measurement of the oil level height. The measured oil level height is the actual oil level, which improves the detection accuracy.

[0019] 4. When the internal temperature of the measuring rod rises, the internal energy of the air bag increases, and the exhaust pipe air inlet hole is in an open state, so the air flow can enter the exhaust pipe through the exhaust pipe air inlet hole and then be discharged. When the temperature drops, the air bag is in a cold-shrinked state, and the sealing plate seals the exhaust pipe air inlet hole, so the measuring rod is in a sealed state, preventing impurities and dust in the air from entering the interior of the measuring rod, thereby improving the service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 is a cross-sectional view of the present invention; Figure 2 A perspective view of the present invention; Figure 3The circuit diagram of the micro-pressure piezoresistive sensor of the present invention; Figure 4 The oil level transmitter circuit diagram of the present invention; Figure 5 is a cross-sectional view of the vent valve of the present invention; Figure 6 It is a three-dimensional diagram of the air-permeable valve of the present invention.

[0021] In the figure, 1. transmitter housing; 101. connecting nut; 2. measuring rod; 201. air vent; 202. threaded joint; 3. micro-pressure piezoresistive sensor; 4. signal processing circuit; 401. chip IC1; 5. vibration sensor; 6. power processing circuit; 7. signal shielding cable; 8. temperature sensor; 9. air valve; 901. exhaust pipe; 902. air storage bag; 903. sealing plate; 904. sealing plate slide; 905. sealing plate piston push rod; 906. push rod compartment; 907. filter screen; 908. exhaust pipe thread; 909. exhaust pipe air inlet; 10. sensor protection cover. DETAILED DESCRIPTION

[0022] The following will describe the implementation methods of the present application in detail with the help of accompanying drawings and examples, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0023] like Figure 1-Figure 6 As shown, the three-parameter combination transmitter using micro-pressure measurement provided in this embodiment includes a transmitter housing 1 and a measuring rod 2 connected by threads. The transmitter housing 1 and the measuring rod 2 are connected by threads, which has a simple structure and is easy to use. It is also convenient for the later inspection and maintenance of the transmitter. A micro-pressure piezoresistive sensor 3 is fixedly arranged at the bottom end of the inner side of the measuring rod 2. A signal processing circuit 4 is fixedly arranged inside the transmitter housing 1. The micro-pressure piezoresistive sensor 3 establishes a communication connection with the signal processing circuit 4. After the micro-pressure piezoresistive sensor 3 is deformed, the information is pushed to the signal processing circuit 4, and the signal is processed by the signal processing circuit 4. The micro-pressure piezoresistive sensor 3 includes The silicon wafer and four high-precision semiconductor strain gauges form a Wheatstone bridge. Glass layers are fixedly arranged on the upper and lower sides of the silicon wafer. A vacuum cavity is established in the middle of the silicon wafer. The pressure enters the sensor vacuum cavity through the pressure induction cavity. The stress silicon film will bulge slightly upward due to the influence of external force and undergo elastic deformation. The resistance of the four high-precision semiconductor strain gauges will change, destroying the balance of the Wheatstone bridge circuit. The Wheatstone bridge will output a voltage signal proportional to the pressure and transmit it to the signal processing circuit 4. The measurement accuracy of this signal can reach 0.01%~0.03%FS, with the advantages of high sensitivity, good linearity and high stability. The micro-pressure piezoresistive sensor circuit of the micro-pressure piezoresistive sensor 3 includes a sliding rheostat R1, a sliding rheostat R2, a sliding rheostat R3 and a sliding rheostat R4. The sliding rheostat R1 and the sliding rheostat R2 are connected in series with resistors R8 and R9, and are connected to a reference voltage REF through a resistor R10. The sliding rheostat R3 and the sliding rheostat R4 are connected in series with resistor R11, and are electrically connected to a common contact COM. The positive output voltage is connected between the sliding rheostat R1 and the sliding rheostat R2, and the sliding rheostat R3 and the sliding rheostat R4 are connected in series with a resistor R11. The negative output voltage is connected between the rheostat R4, the sliding rheostat R1 and the sliding rheostat R3 are connected in parallel with a resistor R7, the resistor R5 and the resistor R6 are arranged in series between the resistor R7 and the positive output voltage, the chip IC401 is arranged on the signal processing circuit 4, the reference voltage REF on the resistor R10 is electrically connected to the pin 3 of the chip IC401, the positive output voltage is electrically connected to the pin 6 of the chip IC401, and the negative output voltage is electrically connected to the pin 5 of the chip IC401. The design of this circuit greatly improves the cost of the circuit; Pin 9 of the chip IC401 is electrically connected to a resistor R13, a common contact COM on the resistor R11 is electrically connected between the pin and the resistor R13, a resistor R17 and a capacitor C1 are arranged in parallel on the resistor R13, a transistor Q1 is electrically connected to the capacitor C1, a resistor R12 is arranged in parallel on the transistor Q1, and the transistor Q1 and the resistor R12 are electrically connected to pin 1 of the chip IC401 after being connected in parallel; The front end of the resistor R17 is connected to the transistor Q2 via the resistor R16, and the base of the transistor Q2 is electrically connected to the pin 13 of the chip IC401 via the resistor R15; A capacitor C5 is provided in parallel between the base of the transistor Q2 and the emitter of the transistor Q2; The collector of transistor Q2 is electrically connected to the collector of transistor Q1; A capacitor C3 is electrically connected between the collector of transistor Q2, and capacitor C3 is electrically connected to pin 14 of chip IC401 through resistor R14. A diode D1 is electrically connected to pin 2 of chip IC401, and diode D1 is output after being electrically connected to resistor R12 through capacitor C6. Transistor Q1 and transistor Q2 can control large current with small current. When a very small current is added between the base and emitter of transistor Q2, a large current change can be obtained between the collector and the emitter. When the base current is large enough, transistor Q2 enters a saturation state, and the resistance between the collector and the emitter becomes very small, which is equivalent to the closed state of the switch. Conversely, when the base current is very small, transistor Q2 is in a cut-off state, and the resistance between the collector and the emitter becomes very large, which is equivalent to the open state of the switch. Therefore, transistor Q2 can realize the on-off of the circuit by controlling the base current. Changing the input signal of transistor Q2 or transistor Q1 can realize the modulation of the output signal. Transistor Q2 or transistor Q1 can amplify the low-power input signal into a high-power output signal. Pin 15 of chip IC401 is electrically connected to capacitor C2 and grounded. The micro-pressure piezoresistive sensor circuit uses a micro-pressure piezoresistive sensor chip and a high-precision silicon pressure chip. After fine signal conditioning, it can measure very small pressure changes, usually 0~0.5KPa. If this pressure change is taken out, it can be represented as a change in the oil level. In addition, this circuit has an obvious advantage, that is, the oil level sensor is placed obliquely, which will not affect the measurement of the oil level height. The measured oil level height is the real oil level, which improves the detection accuracy; Further, such as Figure 1 As shown, a vibration sensor 5 is fixedly arranged inside the transmitter housing 1 directly below the signal processing circuit 4, and the vibration sensor 5 is electrically connected to the signal processing circuit 4. A power processing circuit 6 is fixedly arranged inside the transmitter housing 1 above the signal processing circuit 4, and a signal shielded cable 7 is electrically connected to the power processing circuit 6. The signal shielded cable 7 is fixedly arranged on the upper side of the transmitter housing 1. A temperature sensor 8 is fixedly arranged inside the measuring rod 2 above the micro-pressure piezoresistive sensor 3, and the temperature sensor 8 establishes a communication connection with the signal processing circuit 4. The vibration measurement part mainly measures the vibration of the machine equipment by the vibration sensor 5, and transmits the data to the signal processing circuit 4 for processing and analysis. The temperature measurement part measures the temperature change of the machine equipment by the temperature sensor 8, and provides real-time temperature data, which is convenient for users to detect the thermal operation of the machine equipment. The oil level measurement part measures the oil level in the machine equipment by the micro-pressure piezoresistive sensor 3, and transmits the real-time oil level data to the signal processing circuit 4. It is connected with a variety of general secondary instruments to realize single equipment monitoring, and can also be connected with a computer data acquisition monitoring system for use.

[0024] Further, if Figure 5 and Figure 6 As shown, a vent hole 201 is provided on the measuring rod 2, and a vent valve 9 is fixedly provided inside the vent hole 201. The inside of the measuring rod 2 is connected to the outside through the vent hole 201, so as to improve the detection accuracy. In order to prevent impurities or dust from entering the inside of the vent hole 201, a vent valve 9 is fixedly provided inside the vent hole 201, which can realize exhaust and seal the vent hole 201. Specifically: The air vent valve 9 includes an exhaust cylinder 901 and an air storage bag 902. The exhaust cylinder 901 is provided with an exhaust cylinder thread 908 which is threadedly connected to the air vent 201. The exhaust cylinder 901 and the air storage bag 902 are fixedly provided on the air vent valve 9. The exhaust cylinder 901 is threadedly connected to the air vent 201, which is convenient for installing the air vent valve 9 and improving the convenience of use. The exhaust cylinder 901 is provided with an exhaust cylinder air inlet hole 909. The exhaust cylinder air inlet hole 909 is provided with a sealing plate slide groove 904. The sealing plate 903 is slidably provided inside the sealing plate slide groove 904. The interior of the air storage bag 902 is filled with carbon dioxide gas. A push rod bin 906 is fixedly provided on one side of the bag 902, and a sealing plate piston push rod 905 corresponding to the push rod bin 906 is provided on the sealing plate 903. The sealing plate piston push rod 905 is slidably provided inside the push rod bin 906. After the internal temperature of the measuring rod 2 increases, the internal energy inside the air storage bag 902 increases, pushing the sealing plate piston push rod 905 on the sealing plate 903 to slide inside the push rod bin 906. After the sealing plate 903 slides to the inside of the sealing plate slide groove 904, the exhaust pipe air inlet hole 909 is in an open state, so that the airflow can enter the exhaust pipe 901 through the exhaust pipe air inlet hole 909 and then be discharged; After the temperature drops, the air bag 902 is in a cold contracted state, the pressure inside the air bag 902 decreases, the sealing plate piston push rod 905 slides into the push rod chamber 906, and the sealing plate 903 seals the exhaust pipe air inlet 909, so that the measuring rod 2 is in a sealed state, preventing impurities and dust in the air from entering the interior of the measuring rod 2, thereby improving the service life of the device; In addition, a filter screen 907 is fixedly provided at the port of the exhaust pipe 901, and the filter screen 907 seals the air entering the measuring rod 2, thereby increasing the service life of the micro-pressure piezoresistive sensor 3 and the temperature sensor 8; A threaded joint 202 is provided at the upper end of the measuring rod 2, and a connecting nut 101 corresponding to the threaded joint 202 is provided at the bottom of the transmitter housing 1. The connecting nut 101 and the threaded joint 202 are connected by threaded engagement. The threaded joint 202 on the measuring rod 2 is connected to the connecting nut 101 at the bottom of the transmitter housing 1 by threaded engagement. The installation is convenient and quick, which improves the convenience of use. The bottom of the measuring rod 2 is connected to a sensor protection cover 10, which can increase the overall service life of the measuring rod 2.

[0025] like Figure 1-Figure 6 As shown, the principle of the three-parameter combination transmitter using the micro-pressure measurement method provided in this embodiment is as follows: The micro-pressure piezoresistive sensor 3 includes a silicon wafer and four high-precision semiconductor strain gauges to form a Wheatstone bridge. Glass layers are fixedly arranged on the upper and lower sides of the silicon wafer. A vacuum cavity is established in the middle of the silicon wafer, in which the pressure enters the sensor vacuum cavity through the pressure induction cavity. The stress silicon film will bulge slightly upward due to the influence of external force and undergo elastic deformation. The resistance of the four high-precision semiconductor strain gauges will change, destroying the balance of the Wheatstone bridge circuit. The Wheatstone bridge will output a voltage signal proportional to the pressure and transmit it to the signal processing circuit 4. The measurement accuracy of the signal can reach 0.01%~0.03%FS, with the advantages of high sensitivity, good linearity and high stability. Pin 15 of chip IC401 is electrically connected to capacitor C2 and grounded. The micro-pressure piezoresistive sensor circuit uses a micro-pressure piezoresistive sensor chip and a high-precision silicon pressure chip. After fine signal conditioning, it can measure very small pressure changes, usually 0~0.5KPa. If this pressure change is taken out, it can be represented as a change in the oil level. In addition, this circuit has an obvious advantage, that is, the oil level sensor is placed obliquely, which will not affect the measurement of the oil level height. The measured oil level height is the real oil level, which improves the detection accuracy; After the internal temperature of the measuring rod 2 increases, the internal energy of the air storage bag 902 increases, pushing the sealing plate piston push rod 905 on the sealing plate 903 to slide inside the push rod chamber 906. After the sealing plate 903 slides into the sealing plate slide groove 904, the exhaust pipe air inlet hole 909 is in an open state, so the air flow can enter the exhaust pipe 901 through the exhaust pipe air inlet hole 909 and then be discharged; After the temperature drops, the air bag 902 is in a cold-shrinking state, and the pressure inside the air bag 902 is reduced. The sealing plate piston push rod 905 slides into the push rod compartment 906, and the sealing plate 903 seals the exhaust pipe air inlet hole 909. Therefore, the measuring rod 2 is in a sealed state, preventing impurities and dust in the air from entering the interior of the measuring rod 2, thereby improving the service life of the device.

[0026] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0027] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0028] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. Changes and variations made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A three-parameter combination transmitter using a micro-pressure measurement method, comprising a transmitter housing (1) and a measuring rod (2) connected by threads, characterized in that: A micro-pressure piezoresistive sensor (3) is fixedly arranged at the bottom end of the inner side surface of the measuring rod (2); A signal processing circuit (4) is fixedly arranged inside the transmitter housing (1), and the micro-pressure piezoresistive sensor (3) establishes a communication connection with the signal processing circuit (4); The micro-pressure piezoresistive sensor (3) comprises a silicon wafer and four high-precision semiconductor strain gauges to form a Wheatstone bridge. Glass layers are fixedly arranged on the upper and lower sides of the silicon wafer. A vacuum cavity is established in the middle of the silicon wafer, wherein the pressure enters the sensor vacuum cavity through the pressure induction cavity. The stress silicon film will slightly bulge upward due to the influence of external force and undergo elastic deformation. The resistance values ​​of the four high-precision semiconductor strain gauges will change, destroying the balance of the Wheatstone bridge circuit. The Wheatstone bridge will output a voltage signal proportional to the pressure and transmit it to the signal processing circuit (4). The sensor has the advantages of high sensitivity, good linearity and high stability. The micro-pressure piezoresistive sensor circuit of the micro-pressure piezoresistive sensor (3) comprises a sliding rheostat R1, a sliding rheostat R2, a sliding rheostat R3 and a sliding rheostat R4, wherein the sliding rheostat R1 and the sliding rheostat R2 are connected in series and then connected to a resistor R8 and a resistor R9, and are connected to a reference voltage REF via a resistor R10; The sliding rheostat R3 and the sliding rheostat R4 are connected in series, connected to a resistor R11, and electrically connected to a common contact COM; A positive output voltage is connected between the sliding rheostat R1 and the sliding rheostat R2, and a negative output voltage is connected between the sliding rheostat R3 and the sliding rheostat R4.

2. The three-parameter combination transmitter using micro-pressure measurement according to claim 1 is characterized in that: The sliding rheostat R1 and the sliding rheostat R3 are connected in parallel to a resistor R7, and a resistor R5 and a resistor R6 are connected in series between the resistor R7 and the positive output voltage.

3. The three-parameter combination transmitter using micro-pressure measurement according to claim 1 is characterized in that: The signal processing circuit (4) is provided with a chip IC1 (401), and the reference voltage REF on the resistor R10 is electrically connected to the pin 3 of the chip IC1 (401); The positive output voltage is electrically connected to pin 6 of the chip IC1 (401), and the negative output voltage is electrically connected to pin 5 of the chip IC1 (401); A resistor R13 is electrically connected to the pin 9 of the chip IC1 (401), and a common contact COM on the resistor R11 is electrically connected between the pin and the resistor R13.

4. The three-parameter combination transmitter using micro-pressure measurement according to claim 1 is characterized in that: The resistor R13 is connected in parallel with a resistor R17 and a capacitor C1, the capacitor C1 is electrically connected with a transistor Q1, the transistor Q1 is connected in parallel with a resistor R12, and the transistor Q1 and the resistor R12 are connected in parallel and electrically connected to pin 1 of the chip IC1 (401); The front end of the resistor R17 is connected to the transistor Q2 via the resistor R16, and the base of the transistor Q2 is electrically connected to the pin 13 of the chip IC1 (401) via the resistor R15; A capacitor C5 is connected in parallel between the base of the transistor Q2 and the emitter of the transistor Q2; The collector of the transistor Q2 is electrically connected to the collector of the transistor Q1; A capacitor C3 is electrically connected between the collector of the transistor Q2 , and the capacitor C3 is electrically connected to the pin 14 of the chip IC1 ( 401 ) through a resistor R14 .

5. The three-parameter combination transmitter using micro-pressure measurement according to claim 1 is characterized in that: Pin 2 of the chip IC1 (401) is electrically connected to a diode D1, and the diode D1 is electrically connected to the resistor R12 via a capacitor C6 and then outputs; The pin 15 of the chip IC1 (401) is electrically connected to a capacitor C2 and is grounded.

6. The three-parameter combination transmitter using micro-pressure measurement according to claim 1 is characterized in that: A vibration sensor (5) is fixedly arranged inside the transmitter housing (1) directly below the signal processing circuit (4), and the vibration sensor (5) is electrically connected to the signal processing circuit (4); A power processing circuit (6) is fixedly arranged inside the transmitter housing (1) above the signal processing circuit (4); a signal shielding cable (7) is electrically connected to the power processing circuit (6); and the signal shielding cable (7) is fixedly arranged on the upper side of the transmitter housing (1).

7. The three-parameter combination transmitter using micro-pressure measurement according to claim 1 is characterized in that: A temperature sensor (8) is fixedly arranged inside the measuring rod (2) above the micro-pressure piezoresistive sensor (3), and the temperature sensor (8) establishes a communication connection with the signal processing circuit (4).

8. The three-parameter combination transmitter using micro-pressure measurement according to claim 1 is characterized in that: The measuring rod (2) is provided with a ventilation hole (201), and a ventilation valve (9) is fixedly arranged inside the ventilation hole (201).

9. A three-parameter combination transmitter using micro-pressure measurement according to claim 8, characterized in that: The vent valve (9) comprises an exhaust cylinder (901) and an air storage bag (902); the exhaust cylinder (901) is provided with an exhaust cylinder thread (908) threadedly connected to the air vent (201); the exhaust cylinder (901) is provided with an exhaust cylinder air inlet hole (909); a sealing plate slide groove (904) is provided inside the exhaust cylinder air inlet hole (909); a sealing plate (903) is slidably provided inside the sealing plate slide groove (904); the interior of the air storage bag (902) is filled with carbon dioxide gas; a push rod bin (906) is fixedly provided on one side of the air storage bag (902); a sealing plate piston push rod (905) corresponding to the push rod bin (906) is provided on the sealing plate (903); the sealing plate piston push rod (905) is slidably provided inside the push rod bin (906); A filter screen (907) is fixedly arranged at the port of the exhaust pipe (901).

10. The three-parameter combination transmitter using micro-pressure measurement according to claim 1, characterized in that: The upper end of the measuring rod (2) is provided with a threaded joint (202), and the bottom of the transmitter housing (1) is provided with a connecting nut (101) corresponding to the threaded joint (202), and the connecting nut (101) is connected to the threaded joint (202) by screwing; The bottom of the measuring rod (2) is connected to a sensor protection cover (10).

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