JPH06221864A - Graphite fiber distortion factor measuring sensor - Google Patents

Abstract

PURPOSE:To enable selecting frequency response and output level by attaching a fabric member, with graphite calcined on a hard fabric material, to a synthetic resin member, for improved gauge factor value. CONSTITUTION:A graphite fabric member 1, wherein a graphite is calcined on a hard fabric material, is attached to one side of a thin flexible synthetic resin member 2, and connection terminals 3 and 4 are provided. Since the graphite fabric member 1 is good in expansion and restoration, a gauge factor is large even with minute distortion. For example, the graphite fabric distortion factor measuring sensor 7 is joined to resistors Ra, Rb, etc., for formation of a bridge circuit. A variable resistor Rx is adjusted to the value equal to the resistance before measurement of a sensor 7. The sensor 7 is attached to a an object, and the object is made to cause distortion. Then, the sensor 7 expands for changing resistance, as a result, a resistance balance between the sensor 7 and the variable resistor Rx collapses, and the voltage, proportional to distortion of the sensor 7, occurs between points A and B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a strain sensor, which is a graphite fiber strain rate measuring sensor for measuring the strain rate in each industrial field.

[0002]

2. Description of the Related Art Conventionally, various strain rate measuring sensors have been used in various industrial fields, but in many cases, the electrical characteristics of these sensors have a small change in resistance value proportional to the strain rate.
That is, since the gauge factor value is small, a high sensitivity linear amplifier is required. In addition, the frequency response is 5 Khz for semiconductor diffusion sensors and 1 for wires and metal foil sensors.
The limit is up to Khz. The output level is 20 mV / V for semiconductor diffusion sensors, and 3 mV / V is the maximum for wires, metal foil sensors, etc., and the resistance value can be arbitrarily changed and a high-frequency power source can be used. Absent.

[0003]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The gage factor value which is the electrical characteristic of the conventional strain rate measuring sensor is improved, the frequency response and the output level can be arbitrarily selected, and the resistance value of the sensor is used. Can be arbitrarily determined by.

[0004]

[Means for Solving the Problem] On at least one surface of a thin and flexible synthetic resin member having an arbitrary shape, a grahite fiber member obtained by firing hard fiber material on grahite is mounted, and connecting terminals are provided at opposite ends. It is provided.

[0005]

Therefore, in the graphite fiber strain rate measuring sensor, the resistance value, the frequency response and the output level can be arbitrarily selected.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a graphite fiber strain rate measurement sensor in which a graphite fiber member 1 obtained by firing graphite on a hard fiber material is attached to one surface of a thin and flexible synthetic resin member 2 and connecting terminals 3 and 4 are provided. The perspective view of 7 is shown. The guillafite fiber member 1 made of a hard fiber material used for the graphite fiber strain rate measuring sensor 7 is
Since the elongation and restoration are good, the gauge factor (Gf = dR / Ro) is large even with a slight strain. Further, the graphite fiber strain rate measuring sensor 7 will be described below as the sensor 7. That is, the distortion curve characteristic of the sensor 7 according to the embodiment shown in FIG. 2 is shown, and the resistance value of the sensor 7 is changed from 8000 ohms to 5000 ohms.
FIG. 3 shows a circuit diagram of an application example of the sensor 7 of the present invention, which is a measurement circuit depending on the use of a DC power supply. Sensor 7 and R
x, Ra, Rb, etc. are joined to form a bridge circuit,
Ra and Rb have the same resistance value. Rx is the sensor 7
It is a variable resistor for adjusting to the same resistance value as before measurement. The sensor 7 is attached to the object to be measured, and the variable resistor Rx is adjusted before the distortion is generated in the object to be measured so that the voltage from the DC power supply 10 shows a zero point between the points A and B. After that, strain is generated in the object to be measured, the sensor 7 expands, the resistance value changes, and the resistance value of the sensor 7 and the variable resistor Rx
When the balance with the resistance value of 1 is lost, a voltage proportional to the distorted value of the sensor 7 is generated between points A and B. That is, the output voltage Vo of the amplifier 8 is represented by Vo = (Vb / 4.Rb / Rb + Rc) .Gf. Therefore, in the sensor 7 having a large gauge factor Gf value, the output voltage Vo has a large value. Output voltage V
o is displayed as a distortion rate on the distortion rate indicator 9. FIG. 4 shows a distortion measuring circuit using a low frequency band or a high frequency as a measuring power supply. Since the sensor 7 is made of a graphite fiber material and has a small inductance component, a DC or high frequency HF band measurement power source can be used.
Therefore, the distortion generation voltage is amplified by using the simple AC amplifier 13 and detected by the detector 14, and the distortion rate is shown on the distortion rate indicator 15 after being converted to DC. The distortion factor measuring circuit using the low-frequency to high-frequency power source 12 has an advantage of not requiring zero adjustment. The output voltage Vo 'of the AC amplifier 13 is obtained by the following calculation formula. Vo ′ = [Ro-dR / (Ro-dR + Rs) · Vs]
・ Rb / Ra + Rb ・ Gf

[0007]

As described above, the graphite fiber strain rate measuring sensor according to the present invention has a large gauge factor value, an arbitrary resistance value can be selected, a wide frequency response can be obtained, and a strain rate of an arbitrary shape can be obtained. A sensor for measurement is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a graphite fiber strain rate measurement sensor.

FIG. 2 Distortion curve characteristic diagram of sensor

[Fig. 3] Distortion factor measurement circuit using a DC power supply for the sensor

FIG. 4 is a distortion factor measurement circuit using a low-frequency to high-frequency power source as a sensor.

[Explanation of sign]

 1 ... Graphite fiber member 2 ... Synthetic resin member 3 ... Connection terminal 4 ... Connection terminal 7 ... Sensor 8 ... Amplifier 9 ... Distortion factor display 10 ... DC power supply 12 ... Low frequency to high frequency power supply 13 ... AC amplifier 14 ... Wave detector 15 ...・ Distortion factor display Rx ・ ・ ・ Variable resistor Ra ・ ・ ・ Resistance Rb ・ ・ ・ Resistance Rc ・ ・ ・ Resistance Vo ・ ・ ・ DC amplifier output Vb ・ ・ ・ ・ ・DC power supply Rs: resistance Ro: sensor specific resistance value dR: distortion change resistance value Vo: AC amplifier output Vs: low frequency or high frequency power supply

Claims (1)

[Claims] 1. A thin synthetic resin member having an arbitrary shape, a graphite fiber member obtained by firing a hard fiber material with graphite is mounted on at least one surface of the synthetic resin member, and connecting terminals are provided at opposite ends thereof. A sensor for measuring the strain rate of a graphite fiber, which is characterized in that