CN100357716C - Resistance strained sensor with protector - Google Patents

Abstract

The invention discloses a resistance strain sensor with a protective device, which comprises an elastic body, a resistance strain gauge and a contact, the resistance strain gauge is pasted on the surface of the elastic body, and the contact is fixed on the free end of the elastic body, and it is also provided with There is a protective cover, the protective cover is provided with a concave cavity, one side of the bottom surface of the concave cavity is provided with a boss for fixing the fixed end of the elastic body, and the top and bottom surfaces of the concave cavity are respectively provided with a stopper corresponding to the free end of the elastic body and has a limit The spacing boss is provided with a through hole on the protective sleeve for the contact to pass through. By setting the protective cover, the upper and lower sides of the free end of the elastic body are protected by limit, which ensures the normal operation of the sensor. The limiter is integrated with the main body of the sensor, which avoids the possible installation error of the limit gap during the installation process. ; The protective sheath can be designed into a suitable shape according to needs, and the sensor has a simple structure, is convenient to manufacture, and is low in price.

Description

Resistive strain sensor with protective device

1. Technical field

The invention relates to a sensor, in particular to a resistance strain sensor with a protection device.

2. Background technology

The sensor is an electronic detection device that can receive the information of the object to be measured, and convert the detected information into an electrical signal or other required forms of information according to certain rules and then output it to meet the requirements of information transmission, processing, storage, display, recording and control requirements. It is the first link to realize automatic detection and automatic control. Sensors are classified according to their working principles and can be divided into resistance, capacitance, electromagnetic, inductance, voltage, Hall, photoelectric, grating, thermocouple and other sensors. Resistance strain sensor is a kind of resistive sensor, which is mainly used as a measuring sensor for electronic weighing instruments.

The structure of the resistance strain sensor mainly includes an elastic body, a resistance strain gauge, and a contact. The elastic body is generally made of aluminum alloy and is arranged in a cantilever beam shape. The surface of the elastic body is connected to the external detection circuit through wires. Its working principle is: when the external force acts on the free end of the elastic body cantilever beam, the elastic body will produce elastic bending deformation, so that the resistance strain gauge pasted on its surface will also produce Deformation, after the deformation of the resistance strain gauge, its resistance value will change (increase or decrease), and then the corresponding detection circuit will convert this resistance value change into an electrical signal (voltage or current) output, thus completing the The process of converting an external force into an electrical signal. In actual work, when the applied external force is too large and exceeds the rated load of the elastomer or the sensor is subjected to a strong impact, the internal crystal phase structure of the elastomer material will be damaged, and the lattice grains cannot be restored to their original shape, resulting in physical damage , The parameters such as creep and zero output of the sensor change, and the output error also increases accordingly, which will make the sensor unable to use normally in serious cases. At present, the protection device of the existing resistance strain sensor is to set a limiter above and below the free end of the elastic body, and maintain a certain gap between the limiter and the free end. The gap is determined according to the measurement range of the sensor. When the external force is within the measuring range, the deformation of the elastic body is within the rated amount, and the free end does not touch the stopper; when the external force exceeding the measuring range acts on the sensor, the deformation of the elastic body increases, and the free end and the stopper In contact with each other, the elastic body will not continue to deform and cause physical damage, ensuring the normal operation of the sensor. The existing limiter and the main body of the sensor are generally installed separately and are not integrated together. Even sensors with a limiter are only limited to larger volumes. For general small-volume strain gauge sensors, there is no limiter. Therefore, it is very difficult to install and debug, especially for the adjustment of the limit gap that requires high precision, often due to the large installation error, which affects the normal use of the sensor. In addition, since the performance of the sensor depends on the physical properties of the elastic body and the resistance strain gauge, the shape of the elastic body and the resistance strain gauge cannot be greatly changed under the condition of meeting the use requirements, and when such a sensor is applied to the product In the middle, it has an impact on the overall planning of each component in the product design.

3. Contents of the invention

1. Purpose of the invention: The purpose of the present invention is to provide a resistance strain sensor with a protective device, which integrates the limiter with the sensor body, and can realize the limit in both the upper and lower directions of the elastic body in the sensor. The position ensures the normal operation of the sensor, the shape of the sensor can be designed according to needs, and the structure is simple, the manufacture is convenient, and the production cost is low.

2. Technical solution: The resistance strain sensor with protection device of the present invention includes an elastic body, a resistance strain gauge and a contact, the elastic body has a fixed end and a free end, and the resistance strain gauge is pasted on the upper and lower surfaces of the elastic body , the contact is fixed on the free end of the elastic body, which is characterized in that: it is also provided with a protective cover, the protective cover is provided with a concave cavity, and one side of the bottom surface of the concave cavity is provided with a boss for fixing the fixed end of the elastic body. The top surface and bottom surface of the cavity are respectively provided with a limit boss corresponding to the free end of the elastic body. There is a limit gap between the limit boss and the free end of the elastic body. hole.

Since the protective cover is arranged outside the sensor, the main parts of the sensor located in the protective cover will not be affected by other components in the detection system, effectively protecting the normal operation of the sensor. The limiter is integrated with the main body of the sensor, and the limit gap of the sensor has been adjusted before leaving the factory, which avoids possible installation errors during the installation process.

In order to prevent the protective cover from being in contact with the strain gauge and affect the normal operation of the strain gauge, grooves for accommodating the strain gauge are respectively provided on the top and bottom of the cavity.

For the convenience of adjusting the elastic body, an opening can be provided on the back of the protective cover.

The shape of the protective cover can be set as a cuboid, cylinder or other suitable shapes as required.

Working principle: In the present invention, the top surface and the bottom surface of the concave cavity of the protective sleeve are respectively provided with a limit boss corresponding to the free end of the elastic body, and there is a limit gap determined according to the measurement range of the sensor between the two, so that no matter Whether the external force applied by the contact is upward or downward, when the external force exceeds the measurement range, the free end of the elastic body will be in contact with the top or bottom surface of the concave cavity, that is, both the upper and lower directions of the free end of the elastic body are implemented. Limit protection.

3. Beneficial effects: Compared with the prior art, the present invention has the following characteristics: (1) By setting the protective cover, the free end of the elastic body is respectively limited on the top surface and the bottom surface of the concave cavity of the protective cover, so that no matter the applied external force Whether it is upward or downward, the free end of the elastic body has been limited and protected to ensure the normal operation of the sensor; (2) The elastic body, the resistance strain gauge and the contact are directly set in the protective sleeve, which is effectively protected during work. (3) The limiter is integrated with the main body of the sensor, avoiding the possible installation error of the limit gap during the installation process; (4) The protective cover can be designed into a suitable shape according to the requirements, which is very beneficial to different applications (5) The sensor has a simple structure, is convenient to manufacture, and has low production cost.

4. Description of drawings

Fig. 1 is the front view of the present invention;

Fig. 2 is a top view of the present invention

Figure 3 is a rear view of the present invention.

5. Specific implementation

As shown in FIG. 1 , the resistance strain sensor with protective device according to the present invention includes an elastic body 1 , a resistance strain gauge 2 , a contact 3 and a protective cover 6 . The elastic body 1 of the present embodiment is a double-connected round-hole elastic body. Of course, a plum-shaped four-hole elastic body, a three-beam bending elastic body or a three-beam shearing elastic body can also be used. The elastic body 1 has a fixed end 4 and The free end 5 and the resistance strain gauge 2 are pasted on the upper and lower surfaces of the middle section of the elastic body 1, and are connected with an external detection circuit through wires. The contact 3 is fixed on the upper surface of the free end 5 of the elastic body through screw connection. The protective cover 6 is provided with a concave cavity 7, the elastic body 1, the strain gauge 2 and the contact 3 are all arranged in the concave cavity 7, a boss 8 is provided on one side of the bottom surface of the concave cavity 7, and the fixed end 4 of the elastic body is passed through the screw Or other connection methods are fixed on the boss 8, and the middle parts of the top and bottom surfaces of the concave cavity 7 are respectively provided with grooves 11 for accommodating the resistance strain gauge 2, and the other corresponding to the free end 5 of the elastic body in the concave cavity 7 Side, the top surface and the bottom surface are respectively provided with a limit boss 9, there is a limit gap between the limit boss 9 and the free end 5 of the elastic body, and the gap is determined according to the measurement range of the sensor. As shown in FIG. 2 , a through hole 10 through which the contact 3 passes is also provided on the top surface of the protective cover 6 . As shown in FIG. 3 , an opening 12 for adjusting the elastic body is provided on the back of the protective cover 6 .

Claims (2)

1. A resistance strain sensor with a protective device, which comprises an elastic body (1), a resistance strain gauge (2) and a contact (3), and the elastic body (1) has a fixed end (4) and a free end (5 ), the resistance strain gauge (2) is pasted on the surface of the elastic body (1), the contact (3) is fixed on the free end (5) of the elastic body (1), and it is characterized in that: it is also provided with a protective cover (6) , the protective cover (6) is provided with a concave cavity (7), and one side of the bottom surface of the concave cavity (7) is provided with a boss (8) for fixing the fixed end (4) of the elastic body, and at the bottom of the concave cavity (7) The top surface and the bottom surface are respectively provided with a limit boss (9) corresponding to the free end of the elastic body (5), and there is a limit gap between the limit boss (9) and the free end of the elastic body (5). The sleeve (6) is provided with a through hole (10) through which the contact (3) passes. 2. The resistance strain sensor with protection device according to claim 1, characterized in that grooves (11) for accommodating the resistance strain gauges (2) are respectively provided on the top and bottom surfaces of the cavity (7).

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