Small-range hard flat membrane sensor based on stress partition eliminating rod

Abstract

The invention relates to the technical field of sensor packaging, in particular to a small-range hard flat membrane sensor based on a stress partition eliminating rod, which comprises a sensor compensation plate, a signal connecting plate, a connecting plate pressing ring, a pressure joint, a stress partition rod, a strain gauge and a membrane. The stress partition rod is arranged in the sensor, the front end is welded with the diaphragm, the rear end is welded with the pressure joint, and a signal lead is arranged in the hollow rod body; the sensor compensation plate adjusts output pressure through a temperature compensation coefficient, detects curve parameters of a pressure change curve according to an initial detection period, and judges whether output drift occurs or not; analyzing the drift degree according to the calculated deviation, and judging the cause of the deviation; and judging the fluctuation of the sensor range and the curve according to the curve slope and the slope variance, performing overvoltage protection to adjust the initial detection period, or secondarily judging the sensor range to adjust and judge the judgment criterion of output drift. Thread meshing stress is eliminated through the stress partition rod.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor packaging, and particularly to a small-range hard flat film sensor based on a stress isolation and elimination rod. Background Art

[0002] Hard flat die pressure sensors are widely used in environmental protection chemical coatings, polyurethane equipment, food and pharmaceutical equipment, mud, mud pumps, coal slurry, paper pulp, crude oil, asphalt, and other industrial sites that require anti-blocking. Especially in the food and pharmaceutical equipment, new energy such as lithium batteries, and semiconductor liquid crystal industries, high-precision small-range anti-blocking flat die pressure sensors are needed.

[0003] Currently, there are two types of anti-blocking small-range flat die pressure sensors on the market: ceramic flat die pressure sensors and diffused silicon flat die pressure sensors. The ceramic flat die pressure sensor is not a truly pure flat die pressure sensor in terms of structure, so residues (such as food, medicine, battery slurry, etc.) often remain when the equipment stops working, which will affect food and medicine safety and damage the equipment. Since the diffused silicon flat die pressure sensor has silicone oil filled in the core, once the diaphragm is damaged, it will contaminate food and medicine. In the semiconductor industry, oil leakage will damage core devices such as wafers in batches, causing great economic losses.

[0004] Chinese Patent Publication No.: CN108871654A discloses a hard flat film suspended pressure sensor, which is composed of a sensor core and a sensor housing; a cylindrical inner cavity is formed in the center of the sensor core, and the upper end of the cylindrical inner cavity is provided with a reduced diameter shoulder, the middle part is a floating cavity for installing the sensor core, and the lower end is an expanded inner threaded hole; the sensor core is a hollow cylinder, and the diameter of the middle and upper parts is larger than that of the lower part, so that an annular shoulder is formed in the middle and lower parts; an annular groove is formed in the middle of the outer wall of the hollow cylinder, and an elastic sealing ring is embedded in the annular groove; a resistance strain gauge is attached to the inner bottom surface of the hollow cylinder, and four leads are connected to the resistance strain gauge; the sensor core is installed in the floating cavity through the elastic sealing ring, the upper end is limited by the reduced diameter shoulder, and the lower end is installed in the inner threaded hole through an external threaded locking ring to limit the sensor core in the floating cavity. It can be seen that the hard flat film suspended pressure sensor has the following problems:

[0005] Since the diaphragm thickness corresponding to a small range of high pressure reaches the critical point of stress influence, when using a wrench to tighten the product, the biting force between the external thread of the product and the internal thread of the installation position increases with the increase of the wrench torque. At the same time, the stress generated by the biting force will be transmitted to the diaphragm of the product, causing the diaphragm of the product to deform and thus affecting the zero output of the product. Summary of the Invention

[0006] To this end, the present invention provides a small-range hard flat film sensor based on a stress isolation and elimination rod to overcome the problem that the diaphragm of the sensor in the prior art is deformed due to the thread biting stress between the sensor thread and the installation thread.

[0007] To achieve the above object, the present invention provides a small-range hard flat film sensor based on a stress isolation and elimination rod, including:

[0008] A stress isolation rod disposed inside the hard flat film sensor, the front end of the stress isolation rod is welded to the diaphragm of the hard flat film sensor, and the rear end is welded to the pressure joint;

[0009] A sensor compensation plate disposed on the top of the hard flat film sensor, which can adjust the output pressure through the temperature compensation coefficient of the temperature compensation circuit, draw the pressure change curve of the strain resistance and the output pressure, detect the curve parameters of the pressure change curve according to the initial detection period, and judge whether the hard flat film sensor has output drift; analyze the drift degree according to the calculated deviation, judge the cause of the deviation according to the drift degree; judge the sensor range and the fluctuation of the curve according to the change trend and slope variance of the curve slope, perform overpressure protection to adjust the initial detection period, or, secondarily judge the evaluation criteria for output drift by adjusting the sensor range;

[0010] The stress isolation rod includes,

[0011] A rod base, which is disposed at the front end of the stress isolation rod, the rod base is in a stepped shape, the bottom of the rod base is concave, and a through hole with a trapezoidal contraction is provided in the concave portion. The bottom of the rod base is welded to the diaphragm, and there is a weld at the welding position between the bottom of the rod base and the diaphragm;

[0012] A rod body, which is disposed at the rear end of the stress isolation rod, the top end of the rod body is welded to the pressure joint, the rod body is a hollow structure, and the bottom end of the rod body is integrally formed with the rod base;

[0013] A connecting ring, which is a plate-shaped ring structure and is disposed at the top end of the rod body;

[0014] A stress release groove, which is a cylindrical ring structure and is disposed in the middle of the step of the rod base.

[0015] Furthermore, the hard flat film sensor further includes,

[0016] A signal connection plate, and terminal row pins are arranged on the surface of the connection plate for connecting the internal circuit of the sensor and external devices;

[0017] A connection plate pressing ring, which is an annular structure and is disposed between the sensor compensation plate and the signal connection plate for connecting the sensor compensation plate and the signal connection plate;

[0018] A pressure joint, which is located at the bottom of the sensor compensation plate, has connecting external threads at the front and rear ends, and is provided with a sealing ring on the outside;

[0019] A strain gauge, which is installed on the inner surface of the diaphragm as an open bridge circuit, is connected to the sensor compensation plate through the signal connection plate, and is used to form a complete full-bridge circuit after zero adjustment and temperature compensation via the sensor compensation plate, converting the elastic deformation of the diaphragm into a resistance change;

[0020] A diaphragm, with a strain gauge installed inside it, undergoes a slight deformation when subjected to pressure, and is used to convert pressure into deformation.

[0021] Furthermore, there are 2 groups of 3Pin pin holes provided on the body of the sensor compensation plate, and terminal pin rows are provided on the surface of the signal connection plate. The pin rows of the terminal pin rows pass through the pin holes and are connected to the sensor compensation plate.

[0022] Furthermore, a signal lead wire is provided inside the stress isolation rod. One end of the signal lead wire is connected to the strain gauge, and the other end passes through the stress isolation rod and is connected to the signal connection plate, for transmitting the output signal of the strain gauge to the signal connection plate.

[0023] Furthermore, the strain gauge is an open Wheatstone bridge, which is connected to the sensor compensation plate through the signal lead wire via the signal connection plate, and forms a complete full-bridge Wheatstone bridge circuit after zero adjustment and temperature compensation of the sensor compensation plate.

[0024] Furthermore, the signal lead wire enters from the socket at the front end of the stress isolation rod and exits from the rod body at the rear end of the stress isolation rod.

[0025] Furthermore, weld seams are provided at the connection between the front end of the stress isolation rod and the diaphragm and at the connection between the rear end of the stress isolation rod and the pressure joint.

[0026] Furthermore, the sensor compensation plate plots the pressure change curve of the strain resistance and the output pressure value, and detects the curve slope, strain resistance, and output pressure of the pressure change curve according to the initial detection period;

[0027] The sensor compensation plate calculates the resistance difference according to the minimum resistance value and the initial resistance value of the strain resistance in the pressure change curve, compares the absolute value of the resistance difference with the difference evaluation value, and judges whether the pressure change curve conforms to the resistance-pressure relationship and whether there is output drift.

[0028] Furthermore, after output drift occurs,

[0029] The sensor compensation plate calculates the actual measured value, calculates the estimated deviation between the output pressure and the actual measured value, compares the estimated deviation with the deviation critical value, and determines whether the degree of drift is at the first degree of drift or the second degree of drift;

[0030] When the degree of drift is at the first degree of drift, the sensor compensation plate determines that the reason for the deviation is that the relationship between the recorded temperature value and the resistance is inaccurate, and the output drift is caused by temperature change, and adjusts the temperature compensation coefficient;

[0031] When the degree of drift is at the second degree of drift, the sensor compensation plate determines that the reason for the deviation is the zero drift of the sensor, and sends a signal to adjust the calibration period for calibrating the sensor.

[0032] Further, when the degree of drift is at the second degree of drift, the sensor compensation plate detects the curve slope of the pressure change curve according to the initial detection period,

[0033] If the curve slope gradually tends to zero, the sensor compensation plate determines that the sensor is over-range and issues an alarm signal for overpressure protection;

[0034] If the slope variance is greater than the standard value, the sensor compensation plate determines that the curve of the output pressure fluctuates greatly, adjusts the initial detection period, and uses non-linear compensation to correct the non-linear error.

[0035] Further, when the curve of the output pressure fluctuates greatly,

[0036] The sensor compensation plate calculates the average output pressure according to the pressure change curve, compares the average output pressure with the product of the pressure range and the measurement accuracy error, determines whether the output pressure is close to the lower limit of the pressure range, and adjusts the difference evaluation value.

[0037] Compared with the prior art, the beneficial effect of the present invention is that the device can eliminate the thread biting stress between the sensor thread and the installation thread through the weld between the bottom of the rod seat and the diaphragm and the stress relief groove provided in the middle of the step of the rod seat, avoiding the thread biting stress between the threads from being transmitted to the pressure diaphragm, thereby affecting the change of the zero point and increasing the error of the product. And by designing and introducing a stress relief rod, the structure of the traditional hard flat die pressure sensor that directly welds the sensing pressure diaphragm to the front section of the screw or the front section of the screw with a stress groove is changed. While the stress at the rear welding part is greatly reduced compared with the traditional structure, the stress needs to be transmitted to the front section of the stress relief rod through the stress relief rod, and the slender structure of the stress relief rod further effectively reduces the transmission of stress. Coupled with the sufficient rigidity and strength of the front section structure of the stress relief rod, it can further reduce the thread biting stress between the sensor thread and the installation thread. Thus, the sensor diaphragm is not affected by the thread biting stress between the sensor thread and the installation thread and is deformed.

[0038] Furthermore, the sensor compensation board is used to reduce or eliminate errors caused by environmental factors during the sensor measurement process, amplify the weak resistance change signal to a detectable range and convert it into a standard output signal for easy connection with external devices. Through the temperature compensation circuit, the influence of temperature changes on the measurement accuracy is reduced, and overvoltage protection is also provided to adapt to complex usage environments.

[0039] Furthermore, the connecting plate compression ring can isolate the signal connecting plate and the sensor compensation board, thus avoiding the electrical influence of the output signal in the signal connecting plate by the electrical components in the sensor compensation board, reducing the influence of internal factors on the sensor, and improving the accuracy of the output signal; the signal connecting plate ensures that the pressure signal can be accurately transmitted to external devices, while the compensation board optimizes the signal to improve the signal quality. The two work together to reduce the influence of the external environment on the sensor, thereby improving the measurement accuracy; the design optimization of the signal connecting plate and the compensation board enhances the adaptability of the sensor in complex environments and improves the overall stability of the system.

[0040] Furthermore, the sensor compensation board does not directly monitor temperature or humidity, but can calculate the strain resistance through the output signal of the strain gauge, and monitor environmental factors according to the change of the strain resistance. Combining the compensation method makes the output of the sensor closer to the ideal linear relationship; this device calculates the resistance difference according to the minimum resistance value of the strain resistance in the pressure change curve, and judges whether the strain resistance and the output voltage in the pressure change curve conform to the ideal linear relationship and whether the output parameters of the sensor have output drift by the magnitude of the resistance difference, improving the adaptability and flexibility of the sensor to the environment.

[0041] Furthermore, output drift refers to the gradual increase in the deviation between the output value and the actual measured value of the sensor during long-term use. This drift may be caused by various factors. Temperature is one of the main factors affecting the output accuracy of the sensor. The core of temperature compensation is to correct the drift of the sensor output signal caused by temperature changes; since the resistance value is affected by the environmental temperature, the sensor compensation board needs to set the temperature compensation coefficient according to the corresponding relationship between the temperature value and the resistance of the strain gauge. If the relationship between the temperature value and the resistance is inaccurate, the corresponding set temperature compensation parameters cannot correct the influence of temperature changes on the sensor output signal, resulting in output drift of the output pressure. This device monitors the relationship between the temperature value and the resistance through the sensor compensation board, corrects the temperature compensation coefficient or adjusts the calibration period for calibrating the sensor, significantly improving the measurement accuracy.

[0042] Furthermore, output drift may be caused by various factors. When the pressure borne by the sensor exceeds the maximum range, there will also be a large difference between the output pressure and the actual pressure, resulting in output drift. This device analyzes and detects the curve slope of the pressure change curve to promptly exclude this special case where output drift is judged when the sensor is over-range, protecting the device and improving its adaptability to complex usage environments. In addition to temperature effects, there may also be non-linear errors in the sensor output. The purpose of non-linear compensation is to make the sensor output closer to the ideal linear relationship. This device judges the volatility of the pressure change curve through the slope variance of the curve slope, reduces the initial detection period, thereby increasing the monitoring frequency of the pressure change curve, and promptly optimizes the sensor output curve to make it more in line with the actual measurement requirements, ensuring more accurate measurement results of the sensor in complex environments, improving the reliability of the sensor in harsh environments, and enhancing the measurement accuracy and stability of the sensor.

[0043] Furthermore, when the curve of the output pressure fluctuates greatly and the output pressure is close to the lower limit of the pressure range, the pressure change curve may fall out of the measurement range of the device. This device judges whether the range can meet the requirements of the application scenario based on the relationship between the pressure change curve and the pressure range, adjusts the criterion for judging whether output drift occurs, improves the measurement accuracy, reduces the measurement accuracy error, and increases the minimum range of the sensor for measuring pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic structural diagram of a small-range hard flat film sensor based on a stress isolation elimination rod in an embodiment of the present invention;

[0045] Figure 2 is a schematic cross-sectional structural diagram of a small-range hard flat film sensor based on a stress isolation elimination rod in an embodiment of the present invention;

[0046] Figure 3 is an exploded view of the structure of the stress elimination rod of the hard flat film sensor in an embodiment of the present invention;

[0047] Figure 4 is an exploded view of the structure at the rear end of the hard flat film sensor in an embodiment of the present invention;

[0048] In the figure: 1 - sensor compensation plate, 2 - connecting plate compression ring, 3 - signal connecting plate, 4 - pressure joint, 5 - stress isolation rod, 6 - strain gauge, 7 - diaphragm, 8 - signal lead, 9 - weld, 11 - pinhole, 31 - terminal pin, 41 - sealing ring, 51 - rod seat, 52 - rod body, 53 - connecting ring, 54 - stress relief groove. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] To make the objectives and advantages of the present invention more clearly understood, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only for explaining the present invention and are not used to limit the present invention.

[0050] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0051] It should be noted that in the description of the present invention, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the direction or positional relationship shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0052] In addition, it should also be noted that in the description 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 elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] Please refer to Figures 1-4 as shown in Figure 1 the structural schematic diagram of the small-range hard flat film sensor based on the stress isolation and elimination rod in the embodiment of the present invention; Figure 2 the cross-sectional structural schematic diagram of the small-range hard flat film sensor based on the stress isolation and elimination rod in the embodiment of the present invention; Figure 3 the structural explosion diagram of the stress elimination rod of the hard flat film sensor in the embodiment of the present invention; Figure 4 the structural explosion diagram of the rear end of the hard flat film sensor in the embodiment of the present invention.

[0054] The present invention provides a small-range hard flat film sensor based on a stress isolation and elimination rod, including:

[0055] a stress isolation rod 5 disposed inside the hard flat film sensor, the front end of the stress isolation rod 5 is welded to the diaphragm 7 of the hard flat film sensor, and the rear end is welded to the pressure joint 4,

[0056] the stress isolation rod 5 includes,

[0057] The rod base 51 is arranged at the front end of the stress isolation rod 5. The rod base 51 is in a stepped shape, with a depression at the bottom of the rod base 51. A through hole with a trapezoidal contraction is arranged in the depression. The bottom of the rod base 51 is welded to the diaphragm 7, and there is a weld seam 9 at the welding position between the bottom of the rod base 51 and the diaphragm 7;

[0058] The rod body 52 is arranged at the rear end of the stress isolation rod 5. The top end of the rod body 52 is welded to the pressure joint 4. The rod body 52 is a hollow structure, and the bottom end of the rod body 52 is integrally formed and connected to the rod base 51;

[0059] The connecting ring 53 is in a plate-shaped ring structure and is arranged at the top end of the rod body 52;

[0060] The stress release groove 54 is in a cylindrical ring structure and is arranged in the middle of the step of the rod base 51.

[0061] It can be understood that the stress release groove is an optional structure by preference. The stress isolation rod can fully eliminate the thread biting stress between the sensor thread and the installation thread. The stress release groove plays a role in strengthening the elimination and cannot be used to limit the elimination ability of the stress isolation rod.

[0062] Specifically, this device can eliminate the thread biting stress between the sensor thread and the installation thread through the weld seam 9 between the bottom of the rod base 51 and the diaphragm 7 and the stress elimination groove arranged in the middle of the step of the rod base 51, avoiding the thread biting stress from being transmitted to the pressure diaphragm 7, thus affecting the change of the zero point and increasing the error of the product. And by designing and introducing a stress elimination rod, it changes the structure of the traditional hard flat die pressure sensor that directly welds the induction pressure diaphragm 7 to the front section of the screw or the front section of the screw with a stress groove. While the stress at the rear welding position is greatly reduced compared with the traditional structure, the stress needs to be transmitted to the front section of the stress elimination rod through the stress elimination rod. The slender structure of the stress elimination rod further effectively reduces the transmission of the stress. Coupled with the sufficient rigidity and strength of the front section structure of the stress elimination rod, it can further reduce the thread biting stress between the sensor thread and the installation thread. Thus, the sensor diaphragm 7 is not affected by the thread biting stress between the sensor thread and the installation thread and does not deform.

[0063] The sensor compensation board 1 can adjust the output pressure through the temperature compensation coefficient of the temperature compensation circuit, draw the pressure change curve of the strain resistance and the output pressure, detect the curve parameters of the pressure change curve according to the initial detection period, and judge whether the hard flat film sensor has output drift; analyze the drift degree according to the calculated deviation, judge the cause of the deviation according to the drift degree; judge the sensor range and the fluctuation of the curve according to the change trend and the slope variance of the curve slope, perform overpressure protection to adjust the initial detection period, or, secondly judge the sensor range adjustment to judge the evaluation criteria of the output drift.

[0064] Specifically, the sensor compensation plate 1 is used to reduce or eliminate errors caused by environmental factors during the sensor measurement process, amplify the weak resistance change signal to a detectable range and convert it into a standard output signal for easy connection with external devices. Through the temperature compensation circuit, it reduces the influence of temperature changes on the measurement accuracy and also has overvoltage protection to adapt to complex usage environments.

[0065] The small-range hard flat film sensor based on the stress isolation elimination rod further includes

[0066] The connecting plate pressing ring 2, which is of an annular structure, is arranged between the sensor compensation plate 1 and the signal connecting plate 3 and is used to connect the sensor compensation plate 1 and the signal connecting plate 3;

[0067] The signal connecting plate 3, on the surface of which there are two 3Pin terminal rows 31, is used to connect the internal circuit of the sensor and external devices;

[0068] The pressure joint 4 is located at the bottom of the sensor compensation plate 1, with external threads for connection at the front and rear ends and an O-ring 41 on the outside;

[0069] Preferably, in this embodiment, the O-ring is an ED O-ring.

[0070] Inside the stress isolation rod 5, there is a signal lead 8. One end of the signal lead 8 is connected to the strain gauge 6, enters from the front rod seat 51 of the stress isolation rod 5, exits from the rear rod body 52 of the stress isolation rod 5, and the other end passes through the stress isolation rod 5 and is connected to the signal connecting plate 3 for transmitting signals;

[0071] The strain gauge 6 is installed on the inner surface of the diaphragm 7 as an open bridge circuit, is connected to the sensor compensation plate 1 through the signal connecting plate 3, and is used to form a complete full bridge circuit after zero adjustment and temperature compensation by the sensor compensation plate 1, converting the elastic deformation of the diaphragm 7 into a resistance change;

[0072] Preferably, the strain gauge is an open Wheatstone bridge, which is connected to the sensor compensation plate through the signal lead via the signal connecting plate, and forms a complete full bridge Wheatstone bridge circuit after zero adjustment and temperature compensation by the sensor compensation plate.

[0073] The resistance change rate of the strain gauge 6 is ΔR / R, the strain it receives is ε, and the sensitivity coefficient K is equal to the ratio of the resistance change rate ΔR / R to the strain ε

[0074] The diaphragm 7, inside which the strain gauge 6 is installed, generates a small deformation under pressure, and is used to convert pressure into deformation;

[0075] The deformation of the hard flat diaphragm 7 will cause a change in its internal resistance, and this change is usually proportional to the pressure;

[0076] Detect the change of the resistance through an electronic circuit (such as an amplifier, a compensation circuit, etc.), and convert it into a standard electrical signal (such as 4 - 20 mA, 0 - 5 VDC, etc.) for output.

[0077] Terminal pins 31 are arranged on the surface of the signal connection board 3, and a number of pin holes 11 are arranged on the body of the sensor compensation board 1. The pins of the terminal pins 31 pass through the pin holes 11 and are connected to the sensor compensation board 1.

[0078] Specifically, the connection board pressing ring 2 can isolate the signal connection board 3 and the sensor compensation board 1, thus avoiding the electrical influence of the electrical components in the sensor compensation board 1 on the output signal in the signal connection board 3, reducing the influence of internal factors on the sensor, and improving the accuracy of the output signal; the signal connection board 3 ensures that the pressure signal can be accurately transmitted to the external device, while the compensation board optimizes the signal to improve the signal quality. The two work together to reduce the influence of the external environment on the sensor, thereby improving the measurement accuracy; the design optimization of the signal connection board 3 and the compensation board enhances the adaptability of the sensor in a complex environment and improves the overall stability of the system.

[0079] The sensor compensation board 1 stores the corresponding relationship between the temperature value and the resistance of the strain gauge 6 and the corresponding relationship between the resistance of the strain gauge 6 and the output pressure, and a temperature compensation coefficient is set accordingly according to the corresponding relationship between the temperature value and the resistance of the strain gauge 6;

[0080] The sensor compensation board 1 draws a pressure change curve of the strain resistance and the output pressure value according to the output pressure value and the resistance of the strain gauge 6, and detects the curve slope, strain resistance, and output pressure of the pressure change curve according to the initial detection period to determine whether the output pressure value of the hard flat film sensor has an output drift.

[0081] The sensor compensation board 1 calculates the resistance difference according to the minimum resistance value and the initial resistance value of the strain resistance in the pressure change curve.

[0082] If the absolute value of the resistance difference is less than or equal to the difference evaluation value, the sensor compensation board 1 determines that the pressure change curve conforms to the resistance - pressure relationship and there is no output drift;

[0083] If the absolute value of the resistance difference is greater than the difference evaluation value, the sensor compensation board 1 determines that the pressure change curve does not conform to the resistance - pressure relationship and there is an output drift;

[0084] Wherein, the difference evaluation value is a preset value set according to the allowable error of the calculated strain resistance.

[0085] Specifically, the sensor compensation plate 1 does not directly monitor temperature or humidity, but can calculate the strain resistance through the output signal of the strain gauge 6, and monitor environmental factors according to the change of the strain resistance. By combining the compensation method, the output of the sensor is made closer to the ideal linear relationship. This device calculates the resistance difference according to the minimum resistance value of the strain resistance in the pressure change curve, and judges whether the strain resistance and the output voltage in the pressure change curve conform to the ideal linear relationship, and whether the output parameters of the sensor have output drift, improving the adaptability and flexibility of the sensor to the environment.

[0086] After the output drift occurs, the sensor compensation plate 1 calculates the actual measured value according to the resistance difference and the corresponding relationship between the resistance of the strain gauge 6 and the output pressure stored, calculates the calculation deviation between the output pressure and the actual measured value, analyzes the drift degree according to the calculation deviation, and judges the reason for the deviation according to the drift degree.

[0087] If the calculation deviation is greater than the deviation critical value, the sensor compensation plate 1 judges that the drift degree is at the first drift degree, and the reason for the deviation is that the relationship between the recorded temperature value and the resistance is inaccurate, and the output drift is caused by the temperature change, and adjusts the temperature compensation coefficient.

[0088] Specifically, judge the corresponding relationship between the output pressure and the actual measured value according to the calculation deviation, that is, whether the output pressure is too large or too small, and correspondingly adjust the temperature compensation coefficient up or down according to the output pressure and the actual measured value.

[0089] If the calculation deviation is less than or equal to the deviation critical value, the sensor compensation plate 1 judges that the drift degree is at the second drift degree, and the reason for the deviation is the zero drift of the sensor, and sends a signal to adjust the calibration period for calibrating the sensor.

[0090] Specifically, reduce the calibration period according to the ratio of the calculation deviation to the deviation critical value.

[0091] Among them, the deviation critical value is a preset value set according to the historical data of the deviation value of the output pressure after the output drift occurs.

[0092] Specifically, output drift refers to the gradual increase in the deviation between the output value and the actual measured value of the sensor during long-term use. This drift may be caused by various factors. Temperature is one of the main factors affecting the output accuracy of the sensor. The core of temperature compensation is to correct the drift of the sensor output signal caused by temperature changes. Since the resistance value is affected by the ambient temperature, the sensor compensation board 1 needs to set the temperature compensation coefficient according to the corresponding relationship between the temperature value and the resistance of the strain gauge 6. If the relationship between the temperature value and the resistance is inaccurate, the corresponding set temperature compensation parameters cannot correct the influence of temperature changes on the sensor output signal, resulting in output drift of the output pressure. This device monitors the relationship between the temperature value and the resistance through the sensor compensation board 1, corrects the temperature compensation coefficient or adjusts the calibration period for calibrating the sensor, significantly improving the measurement accuracy.

[0093] When the drift degree is at the second drift degree, the sensor compensation board 1 detects the curve slope of the pressure change curve according to the initial detection period.

[0094] If the curve slope gradually tends to zero, the sensor compensation board 1 determines that the sensor is over-range and issues an alarm signal for overpressure protection.

[0095] The sensor compensation board 1 calculates the slope variance according to the curve slope. If the slope variance is greater than the standard value, the sensor compensation board 1 determines that the sensor application scenario is special, the curve of the output pressure fluctuates greatly, adjusts the initial detection period, and uses non-linear compensation to correct the non-linear error.

[0096] Specifically, the initial detection period is reduced according to the ratio of the standard value to the slope variance.

[0097] Among them, the standard value is a preset value set according to the historical data of the curve slope when the sensor does not have output drift.

[0098] Specifically, output drift may be caused by various factors. When the pressure borne by the sensor exceeds the maximum range, there will also be a large difference between the output pressure and the actual pressure, resulting in output drift. This device analyzes and detects the curve slope of the pressure change curve, and timely eliminates this special situation where the sensor is over-range and judged as output drift, protecting the device and improving the adaptability to complex usage environments. In addition to temperature effects, there may also be non-linear errors in the sensor output. The purpose of non-linear compensation is to make the output of the sensor closer to the ideal linear relationship. This device judges the volatility of the pressure change curve through the slope variance of the curve slope, reduces the initial detection period to increase the monitoring frequency of the pressure change curve, and timely optimizes the output curve of the sensor to make it more in line with the actual measurement requirements, ensuring more accurate measurement results of the sensor in complex environments, improving the reliability of the sensor in harsh environments, and enhancing the measurement accuracy and stability of the sensor.

[0099] In this embodiment, the pressure range of the sensor is 0.1 MPa, the measurement accuracy error is 0.2%, and the influence of zero-point installation stress is less than 0.2%.

[0100] The sensor compensation plate 1 calculates the average output pressure according to the pressure change curve. When the curve of the output pressure fluctuates greatly,

[0101] if the average output pressure is greater than or equal to the product of the pressure range and the measurement accuracy error, the sensor compensation plate 1 determines that the sensor range meets the requirements of the application scenario;

[0102] if the average output pressure is less than the product of the pressure range and the measurement accuracy error, the sensor compensation plate 1 determines that the output pressure is relatively close to the lower limit of the pressure range, the sensor range is lower than the requirements of the application scenario, and adjusts the difference evaluation value;

[0103] Specifically, the difference evaluation value is reduced according to the ratio of the average output pressure to the product.

[0104] Specifically, when the curve of the output pressure fluctuates greatly and the output pressure is close to the lower limit of the pressure range, the pressure change curve may fall out of the measurement range of the device. The device determines whether the range can meet the requirements of the application scenario according to the relationship between the pressure change curve and the pressure range, adjusts the evaluation criterion for determining whether output drift occurs, improves the measurement accuracy, reduces the measurement accuracy error, and increases the minimum range of the sensor for measuring pressure.

[0105] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0106] The above are only the preferred embodiments of the present invention and are not used to limit the present invention; for those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A small-range hard flat film sensor based on a stress isolation and elimination rod, characterized in that: include: A stress isolating rod is arranged inside the hard flat film sensor, wherein the front end of the stress isolating rod is connected to the diaphragm of the hard flat film sensor by welding, and the rear end of the stress is connected to the pressure joint by welding; The sensor compensation plate arranged on the top of the hard flat film sensor can adjust the output pressure through the temperature compensation coefficient of the temperature compensation circuit, draw the pressure change curve of the strain resistance and the output pressure, detect the curve parameters of the pressure change curve according to the initial detection period, and judge whether the hard flat film sensor has output drift; analyze the drift degree according to the estimated deviation, and judge the cause of the deviation according to the drift degree; judge the sensor range and the fluctuation of the curve according to the change trend of the slope of the curve and the slope variance, adjust the initial detection period for overvoltage protection, or, judge the judgment standard of the output drift by adjusting the sensor range for the second time; The stress isolation rod comprises: A rod seat is arranged at the front end of the stress isolation rod, the rod seat is stepped, the bottom of the rod seat is concave, a through hole contracting in a trapezoidal shape is arranged at the concave part, the bottom of the rod seat is welded to the diaphragm, and a weld exists at the welding position of the bottom of the rod seat and the diaphragm; A rod body, which is arranged at the rear end of the stress isolation rod, the top end of the rod body is welded to the pressure joint, the rod body is a hollow structure, and the bottom end of the rod body is integrally connected to the rod seat; A connecting ring, which is a plate-shaped ring structure, is arranged at the top end of the shaft; The stress release groove is a cylindrical ring structure and is arranged in the middle of the step of the rod seat.

2. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 1 is characterized in that: Hard flat film sensors also include, Signal connection board, the surface of which is provided with terminal pins for connecting the internal circuit of the sensor with external equipment; The connecting plate clamping ring is an annular structure and is disposed between the sensor compensation plate and the signal connecting plate to connect the sensor compensation plate and the signal connecting plate; The pressure connector is located at the bottom of the sensor compensation plate, with connecting external threads at the front and rear ends and a sealing ring at the outside; A strain gauge is installed on the inner surface of the diaphragm as an open circuit bridge, connected to the sensor compensation board through the signal connection board, and is used to form a complete full-bridge circuit after zeroing and temperature compensation of the sensor compensation board, and convert the elastic deformation of the diaphragm into resistance change; The diaphragm has a strain gauge installed inside. When subjected to pressure, the diaphragm produces a tiny deformation, which is used to convert pressure into deformation.

3. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 2 is characterized in that: The body of the sensor compensation board is provided with a plurality of pin holes, and the surface of the signal connection board is provided with terminal pins, and the pins of the terminal pins pass through the pin holes and are connected to the sensor compensation board.

4. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 1 is characterized in that: A signal lead is arranged inside the stress isolation rod, one end of the signal lead is connected to the strain gauge, and the other end passes through the stress isolation rod and is connected to the signal connection board, so as to transmit the output signal of the strain gauge to the signal connection board.

5. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 4 is characterized in that: The signal lead enters from a rod seat at the front end of the stress isolation rod and exits from a rod hole at the rear end of the stress isolation rod.

6. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 1 is characterized in that: A weld is provided at a connection between the front end of the stress isolation rod and the diaphragm and at a connection between the rear end of the stress isolation rod and the pressure joint.

7. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 1 is characterized in that: The sensor compensation board draws a pressure change curve of the strain resistance and the output pressure value, and detects the curve slope, strain resistance and output pressure of the pressure change curve according to the initial detection cycle; The sensor compensation board calculates the resistance difference according to the minimum resistance value and the initial resistance value of the strain resistor in the pressure change curve, compares the absolute value of the resistance difference with the difference evaluation value, and determines whether the pressure change curve conforms to the resistance-pressure relationship and whether output drift occurs.

8. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 7 is characterized in that: After output drift occurs, The sensor compensation board estimates the actual measurement value, calculates the estimated deviation between the output pressure and the actual measurement value, compares the estimated deviation with the deviation threshold value, and determines whether the drift degree is at the first drift degree or the second drift degree; When the drift degree is at the first drift degree, the sensor compensation board determines that the reason for the deviation is that the relationship between the recorded temperature value and the resistance is inaccurate, the temperature change causes the output drift, and adjusts the temperature compensation coefficient; When the drift degree is at the second drift degree, the sensor compensation board determines that the cause of the deviation is the sensor zero point drift, and sends a signal to adjust the calibration period for calibrating the sensor.

9. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 8 is characterized in that: When the drift degree is in the second drift degree, the sensor compensation board detects the slope of the pressure change curve according to the initial detection cycle. If the slope of the curve gradually approaches zero, the sensor compensation board determines that the sensor is out of range and sends an alarm signal for overvoltage protection; If the slope variance is greater than the standard value, the sensor compensation board determines that the output pressure curve fluctuates greatly and adjusts the initial detection cycle.

10. The short-range hard flat film sensor based on the stress isolation and elimination rod according to claim 9 is characterized in that: When the output pressure curve fluctuates greatly, The sensor compensation board calculates the average output pressure according to the pressure change curve, compares the average output pressure with the product of the pressure range and the measurement accuracy error, determines whether the output pressure is close to the lower limit of the pressure range, and adjusts the difference evaluation value.

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