CN201215516Y - Differential capacitive load sensor - Google Patents

Abstract

The utility model provides a differential capacitance load sensor, mainly by deciding utmost point post, move utmost point post, measuring element (elastomer), the measuring head, the casing constitutes, when the measuring head receives the measured exogenic action, pass measuring element (elastomer) with this effort, measuring element takes place elastic deformation, along the axial compressed, measuring head and electric capacity move utmost point post and produce corresponding displacement together, then the area of covering between electric capacity sensor two utmost point posts changes, cause the capacitance value of sensor to change thereupon, there is the one-to-one relation in the change volume of capacitance value and the displacement volume of measuring head. The capacitance variation is output to an external circuit through the electrode lead wire, and the external load can be obtained through processing and output. The sensor is characterized by high sensitivity and convenient signal pickup; the polar plates are not contacted, deformed and abraded, and the service life is long; the capacitance sensor is less affected by temperature; the dynamic performance is good.

Description

Differential capacitive load sensor

1. Technical field

The utility model relates to a differential capacitance sensor for detecting various loads (forces).

2. Background technology

At present, among the numerous sensors used for load (force) detection, most of them are resistance strain sensors, and no capacitive sensor products or designs have been released yet. The disadvantages of the resistance strain load sensor are that the detection sensitivity is not high enough, and the general error is about 0.5%; the second is that the resistance strain gauge is easily affected by the ambient temperature, which makes the measurement value inaccurate; Firmness will cause measurement errors; Fourth, the signal change of the resistance strain gauge is weak, which is not conducive to detection.

3. Contents of the invention

The technical problem to be solved by the utility model is to provide a brand-new differential capacitive load sensor to overcome the deficiencies of the prior art.

The technical solution adopted by the utility model is: it is mainly composed of a fixed pole, a moving pole, a measuring element, a measuring head and a housing, the moving pole and the measuring head are fixedly connected as one, and the fixed pole and the housing are fixedly connected as One body, the measuring head and the housing are in clearance fit, the measuring element is installed between the measuring head and the base of the housing; the electrode leads of the fixed pole and the moving pole are drawn out through the lead holes on the base of the housing.

The moving pole column and the fixed pole column are made of ceramic materials, and the surfaces are respectively plated with a layer of silver to form two electrodes of the capacitor. The surface of the silver layer is plated with a layer of inert metal rhodium; layer.

Capacitive equipotential rings are respectively provided at both ends of the electrode of the movable pole.

The positive effects of the utility model are: 1. Compared with the resistance strain load sensor commonly used at present, it has simple structure, strong adaptability, good dynamic response and good temperature stability. Contact, no wear, long life and other advantages; 2. The measuring element is relatively independent installation, easy to disassemble; 3. Adopt the form of differential variable pole area, the linear relationship between input and output is good, and the measurement accuracy is high, which can reach below um level; 4. The poles of moving and constant capacitors are made of ceramic materials with high insulation performance; the electrodes are spray-plated with silver on the ceramic base, and then plated with a layer of inert metal rhodium, which achieves good conductivity of the electrodes and makes the electrodes relatively It is sealed to prevent dust, moisture, corrosion, oxidation, and wear, while reducing the temperature coefficient; 5. The equipotential ring technology used in the moving pole can effectively eliminate the edge effect of the capacitor, making the input and output of the sensor The linear relationship is better and the measurement accuracy is higher; 6. The polyvinyl chloride material is used as the dielectric of the capacitor between the moving and fixed poles, the relative permittivity is high, and the initial capacitance value of the sensor is high, which is convenient for signal extraction, measurement, Process and reduce signal interference and improve measurement accuracy.

4. Description of drawings

Accompanying drawing 1: structural representation of the utility model;

Figure 2: Schematic diagram of the moving pole of the sensor;

Accompanying drawing 3: The fixed pole schematic diagram of this sensor.

5. Specific implementation

As shown in Figure 1, the sensor is composed of a fixed pole 5, a moving pole 6, a measuring element 3, a measuring head 1, and a housing 2. Both the moving pole 6 and the fixed pole 5 are made of ceramic materials, and the shape is Hollow cylinder, the inner surface of moving pole 6 and the outer surface of fixed pole 5 are respectively plated with silver with a thickness of no more than 0.1mm, as two electrodes 11, 13 of the capacitor (as shown in Figures 2 and 3), and then Then plate a layer of inert metal rhodium with a thickness of 0.05mm as the electrode protection layer, so as to achieve good electrical conductivity of the electrode, and make the electrode relatively sealed to prevent dust, moisture, corrosion, oxidation, and wear. It can also reduce the temperature coefficient; outside the electrode 13 of the fixed pole 5, apply a 0.5mm thick polyvinyl chloride layer 14 to increase the dielectric constant and increase the capacitance value. As shown in FIG. 2 , capacitor equipotential rings 10 are respectively provided at both ends of the electrodes of the movable pole 6 , which can effectively eliminate the edge effect of the capacitor. The fixed pole 5 is connected to the housing 2 by bonding, and the moving pole 6 is bonded to the measuring head 1; the measuring element 3 uses a spring in the embodiment, and can be made into a series of products. Different measuring elements with different elastic coefficients are arbitrarily selected; the measuring head 1 and the shell 2 are made of iron-nickel alloy, which can reduce the influence of temperature changes on the measurement accuracy; the measuring head 1 can also be made into different types according to different detection objects; the shell The body 2 is made of iron-nickel alloy material, which has good stability, low temperature coefficient, good shielding effect on the internal capacitance, and good anti-signal interference performance.

The working principle of the utility model is: when the sensor is working, the measuring head 1 is subjected to an external force and transmits the force to the measuring element 3, the measuring element 3 undergoes elastic deformation and is compressed in the axial direction, the measuring head 1 and the moving pole 6 together to produce a corresponding displacement, the coverage area between the two poles of the capacitance sensor changes, causing the capacitance value of the sensor to change accordingly, and the capacitance value is output to the external circuit through the electrode lead wires 4 and 9, and the capacitance value of the sensor is determined by the circuit After detection, processing and output, the size of the external load can be obtained.

Claims (3)

1. A differential capacitive load sensor, characterized in that it is mainly composed of a fixed pole (5), a moving pole (6), a measuring element (3), a measuring head (1), and a housing (2) , the moving pole (6) is fixedly connected with the measuring head (1), the fixed pole (5) is fixedly connected with the housing (2), and the measuring head (1) and the housing (2) are in clearance fit. The measuring element (3) is installed between the measuring head (1) and the base of the housing (2); the electrode leads (4, 9) of the fixed pole (5) and the moving pole (6) pass through the base of the housing (2) The lead hole (8) on the lead out. 2. The differential capacitive load sensor according to claim 1, characterized in that: the moving pole (6) and the fixed pole (5) are made of ceramic materials, and the surfaces are respectively plated with a layer of silver, and the surface of the silver layer is plated There is a layer of inert metal rhodium; the electrode (13) of the fixed pole (5) is also coated with a layer of polyvinyl chloride (14). 3. The differential capacitive load sensor according to claim 1 or 2, characterized in that: the two ends of the electrodes (11) of the movable pole (6) are respectively provided with capacitive equipotential rings (10).

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