Cantilever beam force sensor

Abstract

The utility model discloses a cantilever beam force sensor, which comprises a measuring end, a fixed end and an elastic beam, two independent measuring circuits are adopted, and strain gauge groups of the two independent measuring circuits are respectively arranged on the upper inner surface and the lower inner surface of the elastic beam; specifically, a first strain gauge set Ra is arranged on the upper inner surface of the elastic beam, and a second strain gauge set Ru is arranged on the lower inner surface of the elastic beam. According to the utility model, the strain gauge groups are respectively arranged on the upper inner surface and the lower inner surface of the elastic beam, so that the performance level (PL) and the safety integration level (SIL) of the cantilever beam force sensor are improved on the basis of not increasing obvious cost, PLd and SIL2 can be easily reached, high reliability is realized through a simple circuit, expensive imported products are replaced, and the cost is reduced. Import replacement of domestic cantilever beam force sensors is facilitated, and the high reliability of domestic engineering machinery products is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of cantilever beam sensors, in particular to a cantilever beam force sensor. Background Art

[0002] Cantilever beam force sensors are high-precision, high-performance, and simple weighing force sensors. They are widely used in engineering machinery, packaging equipment, weighing equipment, logistics equipment, firefighting equipment, environmental protection equipment, and other fields.

[0003] Cantilever beam force sensors are mostly rectangular in shape, with the strain zone in the middle of the sensor. They use elastic beams and strain gauges as conversion elements. When force acts on the elastic element (beam), the elastic element (beam) and the strain gauge deform together, causing the resistance value of the strain gauge to change. The strain bridge outputs a voltage signal proportional to the force, which is amplified and converted into a voltage (V) or current (I) signal through a circuit board. Figure 3 As described above, R1 is the strain gauge resistor, and R2, R3, and R4 are fixed value resistors.

[0004] With the development of science and technology, the ISO13849, IEC61508, GB / T16855, and GB / T20438 series of standards have introduced the concepts of Performance Level (PL) and Safety Integrity Level (SIL) for electrical components integrated into safety control systems. These standards place high demands on component reliability to prevent catastrophic impacts on safety control systems caused by component failure, which could affect the implementation of safety functions or result in disasters or accidents.

[0005] Especially in construction machinery, since cantilever beam force sensors are the most core components in the front-end safety control system, they have high requirements for the performance level (PL) and safety integration level (SIL) of cantilever beam force sensors, usually requiring them to reach PLd or SIL2 levels. Corresponding to PLd or SIL2 levels, the requirements for the hardware design architecture (Cat.), component life (MTTFd), circuit fault diagnosis rate (DC), and common cause failure (CCF) of the cantilever beam force sensor are also very high. The design architecture of the product must reach at least Cat. 3 or above, such as Figure 4 、 Figure 5 , that is, the sensor needs to have two independent test circuits, and the two circuits need to have mutual fault monitoring functions as much as possible. Figure 4 、 Figure 5 In: I-input circuit, L-logic circuit, O-output circuit, c-mutual monitoring, m-monitoring, i m -Internal connections.

[0006] The sensors commonly used in the market are single measurement loop circuits such as Figure 6 , some manufacturers have launched the same dual-loop measurement circuit, such as Figure 7 Even with the same strain gauge installation location and circuit structure, mutual fault monitoring between circuits is not possible. The circuit fault diagnosis rate (DC) is low, the common cause failure (CCF) rate is high, and high performance level (PL) and safety integration level (SIL) requirements cannot be met.

[0007] There is currently no effective solution to the above problems. Utility Model Content

[0008] In response to the above technical problems in the related art, the present invention proposes a cantilever beam force sensor, which can overcome the above deficiencies in the prior art.

[0009] In order to achieve the above technical purpose, the technical solution of the utility model is implemented as follows:

[0010] A cantilever beam force sensor comprises a measuring end, a fixed end and an elastic beam, and adopts two independent measuring circuits. The strain gauge groups of the two independent measuring circuits are respectively installed on the upper and lower inner surfaces of the elastic beam; specifically, the upper inner surface of the elastic beam is provided with a strain gauge group R a The lower inner surface of the elastic beam is provided with a strain gauge group R u .

[0011] Furthermore, the measuring circuit includes a power supply, the positive electrode of the power supply is connected to one end of R1 and one end of R3, and the negative electrode of the power supply is connected to one end of R2 and one end of R x One end of R1 and the other end of R2 are connected to the voltmeter V G One end of the R3 is connected to the other end of the R x The other end of the voltmeter V G The other end is connected to R x Strain gauge group R a Or strain gauge group R u .

[0012] Furthermore, a cavity is provided inside the elastic beam.

[0013] Furthermore, V G 0 and full scale respectively.

[0014] Furthermore, R a The corresponding measuring circuit outputs 5V when static and without force.

[0015] The beneficial effects of the present invention are as follows: by arranging strain gauge groups on the upper and lower inner surfaces of the elastic beam respectively, the present invention improves the performance level (PL) and safety integration level (SIL) of the cantilever beam force sensor without significantly increasing the cost, and can easily reach PLd and SIL2. It achieves high reliability with a simple circuit, replaces expensive imported products, facilitates the import substitution of domestic cantilever beam force sensors, and improves the high reliability of domestic engineering machinery products. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 1 is a schematic structural diagram of a cantilever beam force sensor according to an embodiment of the present utility model;

[0018] Figure 2 1 is a schematic diagram of a measurement circuit of a cantilever beam force sensor according to an embodiment of the present utility model;

[0019] Figure 3 This is a diagram of the bridge measurement principle of the existing cantilever beam force sensor according to an embodiment of the present utility model;

[0020] Figure 4 The design architecture of the existing cantilever beam force sensor product according to the embodiment of the utility model Figure 1 ;

[0021] Figure 5 The design architecture of the existing cantilever beam force sensor product according to the embodiment of the utility model Figure 2 ;

[0022] Figure 6 This is a single measurement circuit diagram of an existing cantilever beam force sensor according to an embodiment of the present utility model;

[0023] Figure 7 This is a dual-loop measurement circuit diagram of an existing cantilever beam force sensor according to an embodiment of the present utility model;

[0024] In the figure: 1. Measuring end; 2. Fixed end; 3. Elastic beam; 4. Strain gauge group - R a ; 5. Strain gauge group 2 R u . DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0026] As shown in the figure, a cantilever beam force sensor according to an embodiment of the present invention includes a measuring end, a fixed end, and an elastic beam, and adopts two independent measuring circuits. The strain gauge groups of the two independent measuring circuits are respectively installed on the upper and lower inner surfaces of the elastic beam; specifically, the upper inner surface of the elastic beam is provided with a strain gauge group R a The lower inner surface of the elastic beam is provided with a strain gauge group R u .

[0027] As shown in the figure, the measurement circuit includes a power supply, the positive electrode of the power supply is connected to one end of R and one end of R respectively, and the negative electrode of the power supply is connected to one end of R and one end of R respectively. x One end of the R is connected to the voltmeter V G One end of the R is connected, the other end of the R x The other end of the voltmeter V G The other end is connected to R x Strain gauge group R a Or strain gauge group R u .

[0028] A cavity is provided inside the elastic beam.

[0029] V without afterburner G are 0 and full scale respectively. a The corresponding measuring circuit outputs 5V when static and without force.

[0030] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are described in detail below through specific usage methods.

[0031] In specific use, according to the cantilever beam force sensor described in the utility model, two independent measurement circuits are used, such as Figure 1 , two independent circuit strain gauge groups are installed on the upper and lower inner surfaces of the elastic beam respectively. Figure 1 When pressed downward, the upper inner surface is compressed and shortened by the external force, and the corresponding strain gauge group is also compressed, and the resistance Ra will decrease; the lower inner surface and the strain gauge group are stretched, and the resistance Ru will increase.

[0032] according to Figure 2The circuit diagram corresponds to the upper and lower measurement circuits, the strain gauge group resistance R x It can be R a and R u In order to achieve the difference between the two measurement circuits, the upper and lower measurement bridge circuits are designed to be in the no-force state U by properly matching the resistance values ​​of resistors R1, R2 and R3. DB They are 0 and full scale (maximum value) respectively. When the force is applied, U DB They change to full scale (maximum value) and minimum value (zero) respectively to realize different circuit designs. For example: R a The corresponding measurement circuit outputs 5V when it is static and not stressed. When stressed, the output extends from 5V to 0V; u The corresponding measurement circuit outputs 0V when static and unstressed. When stressed, the output increases from 0V to 5V.

[0033] At the same time, since the upper and lower sets of strain gauges are actually linked with the elastic body under the action of force, they also play the role of mutual monitoring, but there is no direct electrical connection, and the interaction is completed by mechanical connection. Figure 4 Cat.3, which achieves the ability to have a certain diagnostic coverage (DC).

[0034] According to the evaluation of ISO13849, IEC61508, GB / T16855 and GB / T20438 series standards: The above design scheme has a hardware design architecture (Cat. 3) level 3, a high component life (MTTFd), a certain circuit fault diagnosis rate (DC) and a low common cause failure (CCF), which can meet the performance level PLd and safety integration level SIL2.

[0035] In summary, with the help of the above-mentioned technical solution of the present invention, by arranging strain gauge groups on the upper and lower inner surfaces of the elastic beam respectively, the performance level (PL) and safety integration level (SIL) of the cantilever beam force sensor are improved without significantly increasing the cost, and can easily reach PLd and SIL2. High reliability is achieved with a simple circuit, replacing expensive imported products, facilitating the import substitution of domestic cantilever beam force sensors, and improving the high reliability of domestic engineering machinery products.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cantilever beam force sensor, comprising a measuring end (1), a fixed end (2) and an elastic beam (3), characterized in that: Two independent measuring circuits are used, and the strain gauge groups of the two independent measuring circuits are respectively installed on the upper and lower inner surfaces of the elastic beam; specifically, the upper inner surface of the elastic beam (3) is provided with a strain gauge group R a (4), the lower inner surface of the elastic beam (3) is provided with a strain gauge group R u (5).

2. The cantilever beam force sensor according to claim 1, characterized in that: The measuring circuit includes a power supply, the positive electrode of the power supply is connected to one end of R1 and one end of R3 respectively, and the negative electrode of the power supply is connected to one end of R2 and one end of R x One end of R1 and the other end of R2 are connected to the voltmeter V G One end of the R3 is connected to the other end of the R x The other end of the voltmeter V G The other end is connected to R x Strain gauge group R a Or strain gauge group R u .

3. The cantilever beam force sensor according to claim 1, wherein: A cavity is provided inside the elastic beam (3).

4. The cantilever beam force sensor according to claim 2, characterized in that: V without afterburner G 0 and full scale respectively.

5. The cantilever beam force sensor according to claim 1, wherein: R a The corresponding measuring circuit outputs 5V when static and without force.

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