Pressure sensor

Abstract

The pressure sensor comprises a connector, a silicon strain gauge, an insulation pad, a circuit board, a shell and an electrical interface, the connector is located at one end of the shell, the other end of the shell is provided with the electrical interface, the center of the connector is provided with an acquisition cavity, the acquisition cavity is a cylindrical blind hole, and the silicon strain gauge is arranged in the acquisition cavity. A thin bottom wall is formed at the bottom end of the blind hole, the front end of the blind hole is opened at the end part of the joint, and an external measured medium is guided to the bottom wall through the blind hole; a circuit board is fixed in the shell, the insulation pad is arranged between the circuit board and the connector, a plurality of silicon strain gauges are arranged on the front face of the bottom wall, the silicon strain gauges are attached to the front face of the bottom wall, and the silicon strain gauges at least comprise a pressure silicon strain gauge and a temperature silicon strain gauge. The temperature compensation effect is provided, the pressure detection precision is high, and the reliability is good.

Description

TECHNICAL FIELD

[0001] The present application relates to a sensor, in particular to a pressure sensor. BACKGROUND

[0002] The pressure sensor is a sensitive device (strain gauge / silicon strain gauge) pasted on metal. The elastic body sensing area is subjected to external force (air pressure or liquid expansion, compression), and the elastic body sensing area and the sensitive element are deformed, the resistance changes, the voltage applied to the resistor changes, and an identifiable electric quantity signal is output.

[0003] The pressure sensor is one of the most commonly used sensors in the industry, and is widely used in various industrial control environments, involving water conservancy, railway transportation, intelligent building, production control, aerospace, military industry, petrochemical industry, oil well, power, ship, machine tool, pipeline and many other industries.

[0004] The pressure sensor is a high-precision sensor for measuring physical quantities. However, due to different medium temperatures, temperature changes will have a great influence on the measurement results, so the pressure sensor must be temperature compensated. The existing temperature compensation method is to place temperature elements inside the sensor to measure the temperature. These components are on the circuit board, far away from the medium, and the temperature data collected is not accurate, affecting the temperature compensation effect.

[0005] The temperature of the medium is collected by the chip on the circuit board for temperature compensation. However, due to the distance between the chip and the medium, the circuit board is in between, the accuracy of the collected temperature data is not high, resulting in poor effect after temperature compensation of the pressure sensor; and the chip material is different from the silicon strain gauge for measuring pressure of the pressure sensor, the temperature measurement speed is different, which also leads to poor temperature compensation effect of the product. CONTENT OF THE INVENTION

[0006] In view of the defects of the prior art, the present application provides a pressure sensor.

[0007] A pressure sensor comprises a connector, a silicon strain gauge, an insulating pad, a circuit board, a shell and an electrical interface, the connector is located at one end of the shell, the other end of the shell is provided with the electrical interface, a collecting cavity is formed in the center of the connector, the collecting cavity is a cylindrical blind hole, the bottom end of the blind hole forms a thin bottom wall, the front end of the blind hole is open at the end of the connector, and the external measured medium is guided to the bottom wall through the blind hole; the circuit board is fixed in the shell, the insulating pad is arranged between the circuit board and the connector, a plurality of silicon strain gauges are arranged on the front surface of the bottom wall, the silicon strain gauges are attached to the front surface of the bottom wall, and the silicon strain gauges at least comprise a pressure silicon strain gauge and a temperature silicon strain gauge.

[0008] Optionally, the pressure silicon strain gauge is used to detect the deformation of the bottom wall to obtain the pressure value of the measured medium; the temperature silicon strain gauge is used to detect the temperature of the bottom wall to obtain the temperature value of the measured medium; the pressure silicon strain gauge and the temperature silicon strain gauge are connected with the circuit board through a signal transmission line, the signal transmission line passes through the insulating pad and is connected with the pressure silicon strain gauge and the temperature silicon strain gauge; the circuit board is used to perform temperature compensation on the pressure value of the measured medium according to the temperature value of the measured medium; the silicon strain gauge is directly opposite to the blind hole; the silicon strain gauge is a patch type and is welded on the bottom wall; the front surface of the circuit board is provided with a processor and a communication chip; the communication chip is connected with the electrical interface; the temperature silicon strain gauge and the pressure silicon strain gauge are of the same material.

[0009] The pressure sensor of the new type further increases a temperature silicon strain gauge on an original pressure silicon strain gauge, the silicon strain gauges are attached together, the temperature of a medium can be quickly and accurately measured, the temperature silicon strain gauge is of the same material as the pressure measuring silicon strain gauge, when the temperature changes, the resistance values of the three silicon strain gauges change in good consistency, the temperature compensation effect is better than the chip compensation effect, the chip compensation can only achieve an accuracy of 0.02% FS, while the temperature compensation effect of the new type can be improved by more than one time, and can achieve an accuracy of 0.01% FS. The temperature compensation method of the new type does not increase additional operations, is convenient for production, and can greatly improve the temperature compensation effect, the product accuracy and reliability. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 Pressure sensor sectional view

[0011] Figure 2 Pressure sensor sectional view

[0012] Figure 3 Silicon strain gauge distribution diagram DETAILED DESCRIPTION

[0013] In order to make the above-mentioned purposes, features and advantages of the new type more obvious and easy to understand, the specific embodiments of the new type are described in detail below with reference to the drawings, so that the above-mentioned and other purposes, features and advantages of the new type will be clearer. The same reference signs in all the drawings indicate the same parts. The drawings are not necessarily drawn to scale, and the emphasis is on showing the main idea of the new type.

[0014] The structure of the pressure sensor of the new type is as shown in Figure 1 , Figure 2As shown, it includes a connector 1, a silicon strain gauge 3, an insulating pad 4, a circuit board 5, a housing 7, and an electrical interface 8. The connector 1 is located at one end of the housing 7, and the electrical interface 8 is provided at the other end of the housing 7. The connector 1 can be a metal connector, which is fixed to the front end of the housing 7 by means of threads, snap-fit, etc. A sampling cavity 2 is opened in the center of the connector 1. The sampling cavity 2 can be a cylindrical blind hole. One end (bottom end) of the blind hole forms a thin bottom wall 2-1, and the other end of the blind hole opens to the end of the connector 1. In this way, the external measured medium can be guided to the bottom wall 2-1 through this blind hole. The circuit board 5 is fixed inside the housing 7. An insulating pad 4 is provided between the circuit board 5 and the connector 1. The circuit board 5 presses the insulating pad 4 tightly, so that the circuit board 5 is as close as possible to the connector 1.

[0015] In this invention, for ease of description, the side of the bottom wall 2-1 facing away from the blind hole is referred to as the front side of the bottom wall 2-1. Multiple silicon strain gauges 3 are disposed on the front side of the bottom wall 2-1, facing the blind hole. These silicon strain gauges 3 are preferably surface-mount type, attached to the front side of the bottom wall 2-1. For example, the silicon strain gauges 3 can be fixed to the front side of the bottom wall 2-1 by welding. The measured medium passing through the blind hole exerts pressure on and heats the bottom wall 2-1, causing deformation. The silicon strain gauges 3 can sense this deformation and convert it into an electrical signal output to the circuit board 5. Simultaneously, the silicon strain gauges 3 can also measure the temperature of the bottom wall 2-1 and send this temperature data to the circuit board 5.

[0016] Furthermore, the side of circuit board 5 facing the silicon strain gauge 3 is the back side of circuit board 5. No electronic components are required on the back side of circuit board 5; all electronic components are located on the front side. This allows circuit board 5 to completely adhere to the insulating pad 4 and reduces the distance between the silicon strain gauge 3 and circuit board 5. The insulating pad 4 is pressed onto the silicon strain gauge 3, and the silicon strain gauge 3 is connected to circuit board 5 via a signal transmission line. Specifically, this signal transmission line can be led out from the back side of circuit board 5, pass through the insulating pad 4, and connect to the silicon strain gauge 3.

[0017] like Figure 3 As shown, multiple silicon strain gauges 3 are provided. These multiple silicon strain gauges 3 can be divided into pressure silicon strain gauges and temperature silicon strain gauges according to their detection functions. That is, this invention includes at least one pressure silicon strain gauge and one temperature silicon strain gauge, with the pressure silicon strain gauge and temperature silicon strain gauge performing pressure detection and temperature detection independently, respectively. For example, in... Figure 3 The device contains one temperature silicon strain gauge 3-1 and two pressure silicon strain gauges 3-2. All three silicon strain gauges are located on the front of the bottom wall 2-1, directly opposite the acquisition cavity 2, and close to the medium in the acquisition cavity 2. This allows the temperature silicon strain gauge 3-1 to sense temperature quickly and accurately.

[0018] Further, the temperature silicon strain gauge 3-1 for temperature compensation and the pressure silicon strain gauge 3-2 for pressure measurement are of the same material, so that the consistency of the resistance value change trend is good when the temperature changes, and the temperature compensation effect is also increased. For example, the temperature compensation range is -10-70℃, but since the two are of the same material, the consistency is also good when the temperature exceeds this range, and the product can also work normally at a working temperature exceeding the temperature compensation range.

[0019] The circuit board 5 can process the collected pressure value and temperature through the processor 6 on the front side. Specifically, it can obtain the pressure value of the medium through the pressure silicon strain gauge 3-2, obtain the current temperature of the medium through the temperature silicon strain gauge 3-1, and compensate the pressure value according to the current temperature value of the medium, so as to obtain the temperature-compensated pressure value. This pressure value can be sent out through the communication chip through the electrical interface 8.

[0020] In the prior art, the temperature acquisition chip is arranged on the front side of the circuit board 5. This arrangement makes it difficult to press the insulating pad 4 tightly, and increases the distance between the temperature acquisition chip and the measured medium. Since the temperature acquisition chip is separated from the medium in the collection cavity 2 by the insulating pad 4 and the circuit board 5, the measurement temperature accuracy is not high, and the temperature compensation effect is not good.

[0021] The pressure sensor of the present application further comprises a temperature silicon strain gauge on the original pressure silicon strain gauge. The silicon strain gauges are attached together, which can quickly and accurately measure the temperature of the medium. The material of the temperature silicon strain gauge is completely consistent with that of the pressure measurement silicon strain gauge. When the temperature changes, the resistance values of the three silicon strain gauges have good consistency, and the temperature compensation effect is better than the chip compensation effect. The chip compensation can only achieve an accuracy of 0.02% FS, while the temperature compensation effect of the present application can be improved by more than one time, and can achieve an accuracy of 0.01% FS. The temperature compensation method of the present application does not require additional operations, is convenient to produce, and can greatly improve the temperature compensation effect, product accuracy and reliability.

[0022] In the above description, many specific details are described in order to fully understand the present application. However, the above description is only a preferred embodiment of the present application, and the present application can be implemented in many other ways different from the description. Therefore, the present application is not limited by the above disclosed specific embodiments. Meanwhile, any person skilled in the art can make many possible changes and modifications to the above disclosed methods and technical contents without departing from the scope of the present application, or modify them as equivalent embodiments. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the scope of the present application, are still within the scope of protection of the present application.

Claims

1. A pressure sensor, characterized in that, It includes a connector, silicon strain gauges, an insulating pad, a circuit board, a housing, and an electrical interface. The connector is located at one end of the housing, and the electrical interface is located at the other end of the housing. A sampling cavity is formed at the center of the connector. The sampling cavity is a cylindrical blind hole with a thin bottom wall at the bottom end. The front end of the blind hole opens at the end of the connector, and the external measured medium is guided to the bottom wall through the blind hole. A circuit board is fixed inside the housing, and the insulating pad is provided between the circuit board and the connector. Multiple silicon strain gauges are provided on the front side of the bottom wall and are attached to the front side of the bottom wall. The silicon strain gauges include at least one pressure silicon strain gauge and one temperature silicon strain gauge.

2. The pressure sensor according to claim 1, characterized in that, The pressure silicon strain gauge is used to detect the deformation of the bottom wall and obtain the pressure value of the measured medium.

3. The pressure sensor according to claim 2, characterized in that, The temperature silicon strain gauge is used to detect the temperature of the bottom wall and obtain the temperature value of the measured medium.

4. The pressure sensor according to claim 3, characterized in that, The pressure silicon strain gauge and the temperature silicon strain gauge are connected to the circuit board via a signal transmission line, which passes through the insulating pad and is connected to the pressure silicon strain gauge and the temperature silicon strain gauge.

5. The pressure sensor according to claim 4, characterized in that, The circuit board is used to perform temperature compensation on the pressure value of the measured medium based on the temperature value of the measured medium.

6. The pressure sensor according to claim 1, characterized in that, The silicon strain gauge is positioned opposite the blind hole.

7. The pressure sensor according to claim 1, characterized in that, The silicon strain gauge is a patch type and is welded to the bottom wall.

8. The pressure sensor according to claim 1, characterized in that, The processor and communication chip are located on the front side of the circuit board.

9. The pressure sensor according to claim 8, characterized in that, The communication chip is connected to the electrical interface.

10. The pressure sensor according to claim 1, characterized in that, The temperature silicon strain gauge is made of the same material as the pressure silicon strain gauge.

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