A thin-film pressure sensor

Abstract

The present invention discloses a thin-film pressure sensor, which comprises a body. The body is a metal block. A cylindrical metal block protrusion is arranged at the center of the top of the body. A cylindrical first cavity is arranged at the center of the cylindrical metal block protrusion. A cylindrical second cavity is arranged at the bottom of the body. The second cavity and the first space are separated by a thin film. A pressing plate is arranged at the top of the first cavity. Resistance strain gauges are evenly distributed on the toroidal surface where the top of the second cavity extends beyond the first cavity. In this application, the pressing plate causes the deformation of the first cavity, thereby causing the deformation of the thin film. No other external force directly acts on the thin film, ensuring the measurement accuracy of the resistance strain gauges. Moreover, the resistance strain gauges are arranged on the toroidal surface where the top of the second cavity extends beyond the first cavity, which can avoid the overall shear failure phenomenon caused by load overload and improve the measurement reliability of the overall device under extreme working conditions.

Description

Technical Field

[0001] The present invention relates to the field of pressure sensors, and particularly to a thin film pressure sensor. Background Art

[0002] Currently, the vehicle weighing sensor solutions are mainly divided into two types: weighing pressure sensors and deformation displacement sensors.

[0003] Existing weighing pressure sensors mainly include cantilever beam weighing sensors, spoke type pressure sensors, S-type tension and compression sensors, tension sensors, micro sensors, diaphragm box sensors, column type sensors, hanging sensors, multi-dimensional force sensors, static torque sensors, dynamic torque sensors, etc. These sensors are used in various engineering fields, and the measured data and accuracies for various applications are different, and a certain product needs to be selected according to requirements.

[0004] In the field of vehicle weighing system applications, due to factors such as narrow installation space, frequent vibration and shock, and large pre-tightening force, the above-listed conventional weighing pressure sensor products cannot be applied to this specific engineering application. Pressure sensors with a large measurement range are too large to be installed; sensors with a smaller size have too small a measurement range and do not meet the requirements for the bearing capacity required in the vehicle weighing application field.

[0005] The deformation displacement sensor detects the micro deformation or displacement of the vehicle frame or axle and converts it into weight through an algorithm. Its disadvantage is the uncertainty of the material properties of the vehicle frame or axle, resulting in uncontrollable micro deformation or displacement collected, low accuracy, and large error.

[0006] At the same time, in the existing vehicle weighing sensor solutions, there are mostly problems in the performance of the vehicle load under extreme conditions, and it is impossible to avoid the damage to the sensor itself caused by the overall shear force when the vehicle is overloaded, thus affecting the accuracy of vehicle weighing. Therefore, in view of these problems, this application proposes a solution. Summary of the Invention

[0007] Object of the Invention: The object of the present invention is to provide a thin film pressure sensor, which can reduce the error of measurement accuracy caused by uneven force, and at the same time can avoid the damage of overall shear caused by load overload, and improve the reliability of measurement accuracy in the face of extreme working conditions.

[0008] Technical solution: A thin-film pressure sensor according to the present invention includes a body, the body is a metal block, a cylindrical metal block protrusion is provided at the center of the top of the body, a cylindrical first cavity is provided at the center of the cylindrical metal block protrusion, a cylindrical second cavity is provided at the bottom of the body, and the second cavity, the first cavity and the cylindrical metal block protrusion are concentric; the second cavity and the first cavity are separated by a thin film; a pressing plate is provided at the top of the first cavity; resistance strain gauges are evenly distributed on the circular ring surface where the top of the second cavity exceeds the first cavity.

[0009] Preferably, the diameter of the second cavity is larger than the diameter of the first cavity, and the diameter of the second cavity is smaller than the diameter of the cylindrical metal block protrusion.

[0010] The setting that the diameter of the second cavity is larger than the first cavity and smaller than the cylindrical metal block protrusion can ensure that the stress in the first cavity is less than the stress in the second cavity, so that the bending moment on the thin film is more obvious, and further improves the detection accuracy of the resistance strain gauge.

[0011] Preferably, a cylindrical metal block with the same diameter as the first cavity is provided at the bottom of the pressing plate, and the top of the pressing plate is a circular arc protrusion.

[0012] The cylindrical metal block can position the pressing plate, and the circular arc protrusion on the top of the pressing plate can ensure the center of the external force load and help the pressure distribution of the load transfer to be more uniform, ultimately improving the measurement accuracy.

[0013] Preferably, the protruding height of the cylindrical metal block does not exceed 2 mm, and it is interference-fitted with the inner wall of the first cavity.

[0014] The interference fit ensures that the pressing plate can be firmly positioned above the body to bear the load.

[0015] Preferably, the thickness of the thin film is between 0.2 and 1 mm.

[0016] The thickness of the thin film between 0.2 and 1 mm can ensure that the load range applicable to this application is relatively large.

[0017] Preferably, a circuit board electrically connected to the resistance strain gauge is provided in the second cavity, and the circuit board transmits signals outward through wires in the perforations provided on the side of the body.

[0018] Beneficial effects:

[0019] (1). In this application, the load acts on the pressing plate, causing the first cavity to deform and thus the thin film to deform. There is no other external force directly acting on the thin film, ensuring the measurement accuracy of the resistance strain gauge.

[0020] (2) When there is an offset in the position of the external force received by the present application, due to the symmetry of the four sides of the pressing plate with an arc-shaped protrusion, it is ensured that the load still generates an internal force bending moment in the middle and does not affect the accuracy of pressure measurement.

[0021] (3) By arranging the resistance strain gauges on the toroidal surface of the second cavity at the top exceeding the first cavity, the present application can avoid the failure phenomenon of overall shear caused by load overload and improve the reliability of measurement of the overall device under extreme working conditions. Description of the Drawings

[0022] Figure 1 is a side sectional view of the pressing plate in the present application;

[0023] Figure 2 is a side sectional view of the main body in the present application;

[0024] Figure 3 is a top view of the present application. Detailed Embodiment

[0025] The present application will be further described below in conjunction with specific embodiments.

[0026] As Figures 1-3 shown, it is a structural schematic diagram of the present application. In this embodiment, the main body 1 is a metal block. A cylindrical metal block protrusion 2 is provided at the center of the top of the main body 1. A cylindrical first cavity 3 is provided at the center of the cylindrical metal block protrusion 2. A cylindrical second cavity 4 is provided at the bottom of the main body 1. The first cavity 3, the second cavity 4, and the cylindrical metal block protrusion 2 are concentric. A thin film 5 with a thickness of 0.6 mm is provided between the first cavity 3 and the second cavity 4. Resistance strain gauges 7 are evenly distributed on the toroidal surface of the second cavity 4 at the top exceeding the first cavity 3.

[0027] In this embodiment, the diameter of the second cavity 4 is larger than the diameter of the first cavity 3 and smaller than the diameter of the cylindrical metal block protrusion 2. Such a setting can ensure that the stress in the first cavity 3 is less than the stress in the second cavity 4, so that the bending moment received on the thin film 5 is more obvious, and further improves the detection accuracy of the resistance strain gauges 7.

[0028] In this embodiment, a pressing plate 6 is provided at the top of the first cavity 3. The top of the pressing plate 6 is an arc-shaped protrusion. A cylindrical metal block 8 with the same diameter as the first cavity 3 is provided at the bottom of the pressing plate 6. The protruding height of the cylindrical metal block 8 is 2 mm, and it has an interference fit with the inner wall of the first cavity 3. The pressing plate 6 is positioned above the main body 1 through the cylindrical metal block 8 to bear the load. The arc-shaped protrusion at the top of the pressing plate 6 can ensure that the external force load still generates an internal force bending moment in the middle and helps the pressure distribution of the load transfer to be more uniform, ultimately improving the measurement accuracy.

[0029] In this embodiment, a circuit board electrically connected to the resistive strain gauge 7 is disposed in the second cavity 4, and the circuit board transmits signals outward through wires disposed in the through holes 9 on the side surface of the body 1.

[0030] When this embodiment is installed on a vehicle, the second cavity 4 is positioned and installed with a positioning block on the vehicle, the vehicle load is connected to the arc-shaped protrusion on the top of the pressing plate 6, the load presses on the pressing plate 6. Due to the symmetry around the arc-shaped protrusion of the pressing plate 6, internal force bending moments are generated in the middle of the pressing plate 6. The internal force bending moments cause the first cavity 3 to deform, thereby deforming the thin film 5. The deformation of the thin film 5 causes the resistive strain gauge 7 to generate strain, thereby generating a pressure signal.

[0031] In this application, only the deformation of the first cavity 3 causes the thin film 5 to deform, and no other external forces act directly on the thin film 5, ensuring the accuracy of the measurement of the resistive strain gauge 7. The arc-shaped protrusion of the pressing plate 6 ensures that the accuracy of the pressure measurement is not affected when the position of the external force received is offset. Moreover, the resistive strain gauge 7 is disposed on the annular surface of the second cavity 4 that extends beyond the first cavity 3, which can avoid the overall shear failure phenomenon caused by overload of the load and improve the reliability of the overall device in extreme working conditions.

[0032] Finally, it should be noted that the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

Claims

1. A thin-film pressure sensor, comprising a body (1), characterized in that: The body (1) is a metal block. A cylindrical metal block protrusion (2) is provided at the center of the top of the body (1). A cylindrical first cavity (3) is provided at the center of the cylindrical metal block protrusion (2). A cylindrical second cavity (4) is provided at the bottom of the body (1). The second cavity (4), the first cavity (3) and the cylindrical metal block protrusion (2) are concentric. The second cavity (4) is separated from the first cavity (3) by a thin film (5). A pressure plate (6) is provided at the top of the first cavity (3). Resistance strain gauges (7) are evenly distributed on the circular ring surface where the top of the second cavity (4) extends beyond the first cavity (3).

2. The thin-film pressure sensor according to claim 1, characterized in that: The diameter of the second cavity (4) is larger than that of the first cavity (3), and the diameter of the second cavity (4) is smaller than that of the cylindrical metal block protrusion (2).

3. A thin film pressure sensor according to claim 1, wherein: A cylindrical metal block (8) with the same diameter as the first cavity (3) is provided at the bottom of the pressure plate (6), and the top of the pressure plate (6) is a circular arc protrusion.

4. The thin-film pressure sensor according to claim 3, wherein: The protruding height of the cylindrical metal block (8) does not exceed 2 mm, and it has an interference fit with the inner wall of the first cavity (3).

5. A thin-film pressure sensor according to claim 1, characterized in that: The thickness of the thin film (5) is between 0.2 and 1 mm.

6. A thin film pressure sensor according to claim 1, wherein: A circuit board electrically connected to the resistance strain gauges (7) is provided in the second cavity (4), and the circuit board transmits signals outward through wires in the through holes (9) provided on the side surface of the body (1).

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