MEMS pressure sensor calibration test tool

Abstract

The utility model relates to an MEMS pressure sensor calibration test tool, which comprises two technical schemes, namely a calibration test fixed pressure sensor and a calibration test detachable pressure sensor. According to the two kinds of sensors or modules, firstly, MEMS pressure sensors or modules are fastened to a cuboid high-pressure pressure base formed by machining brass through threaded connectors, the high-pressure pressure base is provided with three sets of nine high-pressure oil ways which are communicated with one another, and connecting threads are designed to be conical threads and are matched with rubber rings for sealing and fastening; tapered threads are used for preventing high-pressure oil leakage and ensuring constant pressure, three groups of nine channels are narrow and small oil path space, so that calibration test pressure is stable, time for reaching pressure required by calibration is shortened, calibration test efficiency is improved, brass materials are selected, the MEMS pressure sensor can rapidly reach the set temperature of a constant-temperature box, and the calibration test efficiency is improved. And the influence caused by temperature deviation of the sensor is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to MEMS pressure sensor calibration test technical field, specifically a kind of MEMS pressure sensor calibration test tool. BACKGROUND

[0002] MEMS pressure sensor is a kind of device that can convert the pressure applied on the sensor sensitive membrane into measurable voltage or current through the micro deformation of sensitive membrane, which is widely used in automotive, aviation, medical and other fields, and its precision and stability requirements for sensor are extremely high.

[0003] Generally, the micro deformation of MEMS pressure sensor sensitive membrane cannot be directly measured or its value is too small, at this time, it needs to be converted into standard voltage or current signal through the adjustment and amplification of signal conversion circuit, and this chip that can adjust and amplify micro signal is called signal conditioning chip (abbreviated as ASIC).

[0004] Generally, MEMS pressure sensor core and ASIC conditioning core are combined and sealed in a tube shell or plastic package, to form MEMS pressure sensor module;Sometimes, MEMS pressure sensor core and ASIC conditioning core are also packaged separately, and then connected through a connecting plate to form a MEMS pressure sensor module.

[0005] No matter which form of MEMS pressure sensor module is used, in the production and manufacturing stage from sensor module to final sensor product, the produced pressure sensor needs to be calibrated and tested, and the MEMS pressure sensor module with sensitivity, accuracy, nonlinearity, hysteresis and other static indicators exceeding the design requirements after calibration and test is discarded to ensure that each MEMS pressure sensor shipped is a good product;The user of pressure sensor still needs to test and screen each parameter before use. Therefore, whether it is a pressure sensor manufacturer or a pressure sensor user, a calibration and test tool is needed in the process of calibration and test.

[0006] MEMS pressure sensor is usually placed in a closed container and connected to compressed air during calibration and test, and then the closed container is placed in a constant temperature environment, and the calibration and test system and MEMS pressure sensor can communicate and read and write data.

[0007] Compressed air is typically supplied via steel cylinders. High-pressure compressed air, reaching tens of megapascals, is introduced into a pressure controller through a pressure reducing valve at the cylinder's outlet to obtain a stable and controllable pressure. This controllable pressure is then connected to a pressure sensor via a pipeline. However, the connectors and air passages connecting the sensor are prone to leaks, overpressure, and other high-explosive hazards. Therefore, in actual production or verification applications where the pressure exceeds 0.8 MPa, hydraulic or hydrostatic pressure is often used instead of high-pressure compressed air for sensor calibration testing. This invention prioritizes the use of high-pressure oil for calibration testing. Summary of the Invention

[0008] The purpose of this invention is to provide a calibration and testing fixture for MEMS pressure sensors, taking into account the environmental and on-site safety requirements when calibration testing requires a pressure greater than 0.8 MPa in actual production.

[0009] The MEMS pressure sensor calibration and testing fixture consists of two technical solutions: both solutions utilize a high-pressure base, which is connected to the oil outlet pipe of a piston hydraulic press. High-pressure oil enters three sets of nine-channel pathways through an access hole on one end face of the high-pressure base to provide constant pressure to the pressure sensor. The first technical solution is used for calibrating and testing fixed pressure sensors, while the second technical solution is used for calibrating and testing detachable pressure sensors. The two technical solutions are suitable for different calibration and testing occasions, and users can choose according to the specific application environment of their products.

[0010] Furthermore, this high-pressure base has a rectangular shape and is made of brass. A high-pressure oil inlet is located on the side of the high-pressure base, connecting to a piston-type hydraulic pressure gauge. High-pressure oil enters through the high-pressure oil inlet, continuously supplying a constant pressure. The upper surface and adjacent sides of the high-pressure base have interconnected high-pressure oil or water channels. During calibration testing, the MEMS pressure sensor is connected to the high-pressure oil channels on the high-pressure base via an adapter. Both the inlets of the high-pressure oil channels and the high-pressure oil inlet are provided with tapered threads.

[0011] The inlets of the high-pressure oil circuits are located at the tri-division points on the surface of the high-pressure base. There are three groups of nine interconnected high-pressure oil circuits on the rectangular top surface and two adjacent rectangular sides of the cuboid. The three high-pressure oil circuits on the top surface and two adjacent rectangular sides are collectively referred to as one group. Each group of three high-pressure oil circuits is located at the tri-division points along the length of the rectangle on the three rectangular sides. One of the two square end faces of the cuboid has a threaded hole at its center. This threaded hole serves as the high-pressure oil inlet connecting the three groups of nine interconnected high-pressure oil circuits. The wall thickness of the nearest high-pressure oil circuit inlet is greater than 10mm. All nine threaded holes connecting the high-pressure oil circuits are tapered threads. This multi-channel structure significantly improves calibration and testing efficiency compared to traditional single-channel calibration and testing fixtures. The combination of tapered threaded holes and rubber sealing rings effectively prevents leakage of the liquid medium, ensuring pressure stability during the calibration and testing process.

[0012] Furthermore, the first technical solution is used for calibrating and testing fixed pressure sensors. These fixed pressure sensors are typically final sensor products formed by assembling sensor modules into a fixed housing. These final sensor products usually have pre-installed external connectors, which vary in form, including hexagonal nuts and square nuts, but the internal thread is typically 7 / 16-20UNF. If a sensor fails calibration testing, it must be discarded or used with reduced requirements. This first technical solution is generally suitable for device manufacturers or sensor users with high yield rates for testing and screening.

[0013] Furthermore, the first technical solution uses a fixed pressure sensor connector made of brass, featuring a double-ended, equal-length bolt with a hexagonal center on both ends. The bolt cylinder has a 3-8mm high-pressure oil channel. The thread specification at one end must match the pre-installed external connector on the final pressure sensor and fit well. The hexagonal design in the center of the double ends facilitates assembly. Users can use different threaded adapters to accommodate pressure sensors with different thread specifications, broadening the applicability. This reduces the hassle of frequent switching between different sensor brands, saving production and testing costs and improving calibration and testing efficiency.

[0014] Furthermore, the second technical solution is a detachable pressure sensor connector for calibrating and testing detachable pressure sensors. The detachable pressure sensor connector is a detachable pressure sensor mounting base made of brass. One end of the mounting base has an externally threaded post that connects to a high-pressure base, with a 3mm-8mm high-pressure oil channel at the center of the post. Connected to this externally threaded post is an external hexagonal nut, the other end of which connects to a wrapping tube. Inside the wrapping tube is a support platform where a sealing rubber ring is placed. The pressure sensor is then inverted and mounted on the sealing rubber ring, and secured inside the wrapping tube using a threaded tightening device with holes. This detachable pressure sensor is formed by fixing a pressure sensor module to the detachable pressure sensor mounting base using a sealing rubber ring and a MEMS pressure sensor fastening sleeve. With this detachable structure, unqualified pressure sensor modules during calibration testing can be replaced and recalibrated. Other structures besides the sensor module can be reused multiple times, effectively reducing manufacturing costs for sensor manufacturers.

[0015] Based on the above, the tooling proposed in this application is smaller in size and has higher controllability and precision compared to tooling using compressed air. Specifically, the high-pressure base only provides pressure input, and all the connecting cables used for calibration and testing are output through the cable at the rear end of the sensor, which greatly reduces the volume compared to the sealed container used in low-pressure testing.

[0016] The technical solution provided by this utility model brings considerable benefits. The benefits are manifested in the smaller high-pressure space, which ensures a shorter pressure stabilization time during sensor calibration testing. The smaller high-pressure space also facilitates pressure stabilization. The tapered thread on the high-pressure base prevents leakage of the high-pressure liquid medium, ensuring pressure stability within the high-pressure space. Furthermore, the high-pressure base is made of brass, a high-performance material with excellent thermal conductivity, allowing heat to be easily conducted. Placing this high-pressure base in a constant-temperature chamber makes it easier for the sensor module to quickly reach a constant temperature, reducing the risk of inaccurate calibration test data acquisition due to large sensor temperature deviations. The commercial benefits are reflected in the calibration test fixture manufactured using this utility model's technical solution. The design incorporates a 3-group 9-channel structure and both fixed and detachable structures, making the calibration test fixture widely applicable and highly efficient. This saves manufacturing costs for sensor manufacturers and improves the selection efficiency for sensor users. Attached Figure Description

[0017] Figure 1 This invention provides a fixed calibration and testing scheme for the MEMS pressure sensor calibration and testing fixture.

[0018] Figure 2This is a schematic diagram of the installation of the fixed MEMS pressure sensor module of this utility model.

[0019] Figure 3 This invention relates to a fixed pressure sensor and a high-pressure base adapter.

[0020] Figure 4 A high-pressure base for the calibration and testing fixture of the MEMS pressure sensor of this utility model.

[0021] Figure 5 This invention provides a detachable calibration and testing solution for the MEMS pressure sensor calibration and testing fixture.

[0022] Figure 6 This is a schematic diagram of the installation of the detachable MEMS pressure sensor module of this utility model.

[0023] 1. Fixed pressure sensor; 101. MEMS pressure sensor module; 102. External hexagonal bolt for fixed pressure sensor; 2. Connector between fixed pressure sensor and high-pressure base; 3. High-pressure base; 301-309. Threaded hole for channel pressure sensor connection; 310. Threaded hole for high-pressure oil pipe access; 4. Demountable pressure sensor; 401-403. Demountable pressure sensor mounting base; 404. Sealing rubber ring; 405. MEMS pressure sensor module; 406. MEMS pressure sensor fastening sleeve. Detailed Implementation

[0024] To make the technical solutions and advantages of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0025] In further detail, the same function is represented by the same number in the accompanying drawings. It should be noted that the terms "front", "back", "left", "right", "up" and "down" used in the description of this utility model refer to the directions in the accompanying drawings, and "outermost" and "innermost" refer to the inner and outer sides of the sensor.

[0026] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0027] As attached Figure 1 ~Attached Figure 4 The diagram shows a fixed calibration test scheme for MEMS pressure sensors, suitable for pressure sensor manufacturers or users. The usage methods for both are explained below.

[0028] Furthermore, the MEMS pressure sensor manufacturer first assembles the MEMS pressure sensor module 101 inside the fixed pressure sensor 1, then connects and tightens the external hexagonal bolt 102 of the fixed pressure sensor to the high-pressure base connector 2. Before using the high-pressure base connector 2, a sealing rubber gasket should be installed on the thread to ensure a good seal between the fixed pressure sensor 1, the high-pressure base connector 2, and the high-pressure base 3.

[0029] Furthermore, after assembling the aforementioned connectors, the MEMS pressure sensor and the high-pressure base are placed together in the constant temperature chamber, the calibration or test temperature is set, and the signal output cable at the rear of the sensor is led out through the outlet hole of the constant temperature chamber to the terminal of the calibration or test system; at this point, the gas path and circuit connection inside the constant temperature chamber are completed.

[0030] Furthermore, the stainless steel high-pressure oil pipe at the output end of the piston-type hydraulic pressure gauge is connected to the high-pressure pressure base through the outlet hole of the constant temperature chamber, thereby achieving constant pressure connection with the sensor.

[0031] This completes the interaction between the calibration test system and the MEMS pressure sensor in technical solution 1 of this utility model.

[0032] As attached Figure 5 ~Attached Figure 6 As shown, this is a calibration and testing scheme for detachable MEMS pressure sensors (modules), which is more commonly used by MEMS pressure sensor manufacturers.

[0033] Furthermore, for the detachable MEMS pressure sensor, the MEMS pressure sensor module 405 / 101 must be installed before calibration testing.

[0034] Furthermore, during the assembly of the detachable MEMS pressure sensor module, the sealing rubber ring 404 should first be placed inside the detachable pressure sensor mounting base 401-403, and then the MEMS pressure sensor module 405 / 101 should be placed in. The side of the MEMS pressure sensor module with the sensor should face the direction of the external thread 401 of the detachable pressure sensor mounting base. After placing it flat, the MEMS pressure sensor fastening sleeve 406 should be screwed into the internal thread of the detachable pressure sensor mounting base 403 using a special two-angle wrench and tightened. At this point, the assembly of the detachable MEMS pressure sensor is complete.

[0035] Furthermore, after the detachable MEMS pressure sensor is assembled, the detachable pressure sensor mounting base 401 is fitted with a sealing rubber ring and screwed into the tapered threaded holes of the high-pressure base 301-309 and tightened. At this point, the connection between the detachable MEMS pressure sensor 4 and the high-pressure base 3 is completed.

[0036] Furthermore, following the same fixed calibration test steps, the completed detachable MEMS pressure sensor and high-pressure base are placed together in the constant temperature chamber, the calibration or test temperature is set, and the signal output cable at the rear of the sensor is led out through the constant temperature chamber lead-out hole to the calibration or test system terminal; at this time, the gas path and circuit connection in the constant temperature chamber are completed.

[0037] Furthermore, the stainless steel high-pressure oil pipe at the output end of the piston-type hydraulic pressure gauge is connected to the high-pressure pressure base through the outlet hole of the constant temperature chamber, thereby achieving constant pressure connection with the sensor.

[0038] This completes technical solution 2 of this utility model, the interaction between the calibration test system and the MEMS pressure sensor.

[0039] The embodiments described above are merely some embodiments of this utility model, and not all embodiments. For those skilled in the art, various modifications and variations can be made to the embodiments of this utility model, such as the dimensions of the high-pressure base cuboid, the number of connecting pressure sensor channels, and the form of the hydraulic pressure gauge. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A calibration and testing fixture for a MEMS pressure sensor, characterized in that, It includes a high-pressure base, which is rectangular in shape and made of brass. The high-pressure base has a high-pressure oil inlet on its side, which connects to a piston-type hydraulic pressure gauge. High-pressure oil enters through the high-pressure oil inlet and continuously supplies a constant pressure. The high-pressure base has interconnected high-pressure oil passages on its upper surface and adjacent sides. During calibration testing, a MEMS pressure sensor is connected to the high-pressure oil passages on the high-pressure base via an adapter. Both the inlet of the high-pressure oil passages and the high-pressure oil inlet are provided with tapered threads.

2. The MEMS pressure sensor calibration and testing fixture according to claim 1, characterized in that, The inlets of the high-pressure oil circuit channels are located at three equal points on the surface of the high-pressure base; the high-pressure oil circuit channels are grouped into three groups, with a total of nine channels interconnected; the wall thickness of the high-pressure oil inlet is greater than 10mm from the nearest high-pressure oil circuit channel.

3. The MEMS pressure sensor calibration and testing fixture according to claim 1, characterized in that, The adapter is either a fixed pressure sensor connector or a detachable pressure sensor connector.

4. The MEMS pressure sensor calibration and testing fixture according to claim 3, characterized in that, The fixed pressure sensor connector is a double-ended equal-length bolt made of brass, with an outer hexagon in the middle of the double ends and a 3-8mm high-pressure oil channel in the middle of the bolt cylinder.

5. The MEMS pressure sensor calibration and testing fixture according to claim 3, characterized in that, The detachable pressure sensor connector is a detachable pressure sensor mounting base made of brass. One end of the mounting base has an external threaded post that can be connected to a high-pressure base, and the center of the post has a 3mm to 8mm high-pressure oil channel. Connected to this external threaded post is an external hexagonal nut, and the other end of the external hexagonal nut is connected to a wrapping tube. Inside the wrapping tube is a support platform, on which a sealing rubber ring is placed. The pressure sensor is then inverted and mounted on the sealing rubber ring, and the pressure sensor is fixed inside the wrapping tube by a threaded tightening device with holes.

6. The MEMS pressure sensor calibration and testing fixture according to claim 1, characterized in that, The tapered thread specification is 7 / 16-20UNF.

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