JPS6388487A - Method for detecting abnormality of face part in shield excavator - Google Patents

Abstract

PURPOSE:To simplify detect abnormality with good accuracy, by providing an electrode to the outer peripheral part of the front surface part of the cutter head in a shield excavator and detecting the abnormality of a face part on the basis of the dielectric constant between said electrode and an opposed electrode. CONSTITUTION:Two electrodes 3, 4 are symmetrically arranged to the outer peripheral surface of the cutter head 2 of a shield excavator 1 so as to be positioned in the recesses 2a provided to the surface of the head 2 in electrical insulation from the head 2 and are electrically connected to a detection circuit 5 through a slipping mechanism. A rotary position detector 6 detects the rotary position from the reference point of the head 2 and the output signal thereof is inputted to the circuit 5. Herein, the dielectric constants epsilon, epsilon' between the skin plate 7 supporting the head 2 in a freely rotatable manner and the electrodes 3, 4 are determined by the medii therebetween. Therefore, by comparing the dielectric constants epsilon, epsilon', the abnormality of a face part 8 can be detected. By this method, abnormality and an abnormal position can be simply detected with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the state of a face portion applied to a shield excavator.

[Conventional technology]

Conventionally, the following methods have been implemented to detect the state of the face.

■) Method of monitoring the flow rate and density of mud feeding and drainage 11) Method of observing the reaction force of a detection rod mechanically protruding toward the face 111) Ultrasonic pulse echo method IV) Radio wave pulse echo method [Invention [Problems to be solved] However, in method j), there is a problem of time delay when the transportation pipe is long, and in method 11), the rotation of the cutter face is stopped to prevent damage to the rod. Create the inconvenience of having to do it.

Furthermore, in the ultrasonic Barseniko method (1ii), because the attenuation due to the fixed sediment in front of the vibrator is severe, there is no means to remove the fixed sediment (for example, creating a clear water column with a jet water stream and placing the vibrator in it). This will require a large-scale structure. Furthermore, the radio wave pulse echo method (IV) has the following drawbacks. That is, the dielectric constant and electrical conductivity change depending on the soil quality, which means that the radio wave propagation velocity changes depending on the soil quality. As a result, a phenomenon occurs in which pulse reflection times differ even for objects at the same distance, and this appears as a measurement error.

[Means for solving problems]

In order to solve the above-mentioned conventional problems, in the present invention, an electrode is disposed on the outer periphery of the front surface of the cutter head in a shield excavator, and abnormalities in the face are detected based on the dielectric constant between this electrode and a counter electrode. That's what I do. Further, the rotational position of the cutter head is detected, and the position of the abnormality is detected based on this rotational position.

[Effect]

In the present invention, a change in the state of the face portion is understood as a change in dielectric constant.

〔Example〕

Embodiments of the method according to the present invention will be described below with reference to the drawings.

FIG. 1 illustrates a shield excavator to which the method according to the invention is applied. In the figure, two electrodes 3 and 4 are arranged symmetrically on the outer peripheral surface of a cutter head 2 of a shield excavator 1.

As shown in FIG. 2, the electrodes 3 and 4 are disposed in a recess 2a provided on the surface of the cutter head 2 and are electrically insulated from the head cutter 2, and are not shown. It is electrically connected to the detection circuit 5 via a slipping mechanism.

The rotational position detector 6 detects the rotational position of the cutter head 2 from a reference point, and its output signal is input to the detection circuit 5. Note that this rotational position detector 6 includes:
The rotational force of the cutter head 2 is transmitted, for example, via gears (not shown).

As this detector 6, for example, a potentiometer, an absolute encoder, or the like is used.

Here, the principle of the present invention will be briefly explained.

The dielectric constant ε between the skin plate 7, which rotatably supports the cutter head 2, and the electrode 3 is determined by the medium between them, and similarly, the dielectric constant ε′ between the skin plate 7 and the electrode 4 is also determined by the medium between them. Determined by medium. Therefore, by comparing the dielectric constants ε and ε', abnormalities in the face portion 8 can be detected. For example, as shown in FIG. 1, if a collapse occurs in the upper part of the canterhead 2, the above dielectric constant ε becomes smaller than the dielectric constant ε', so it is difficult to know the occurrence of this collapse. can.

FIG. 3 illustrates the configuration of the detection circuit 5. As shown in FIG.

In the figure, a capacitor 9 has the electrode 3 as one electrode and the skin plate 7 as an opposite electrode. Further, in the capacitor 10, the electrode 4 is used as one electrode, and the skin plate 7 is used as the opposite electrode. The electrode 7 made of a skin plate is connected to the ground line of the detection circuit 5.

Transistor 5 provided in charging/discharging section 5A of detection circuit 5
01 is turned on and off by the output pulse S of the pulse generator 502 shown in FIG. 4(a), and its collector is connected to the resistor 50.
It is connected to the electrode 3 via 3.

When the transistor 501 is turned off, the resistor 5
Capacitor 11 is charged to power supply voltage VCC through transistor 03 and resistor 504, and when it is turned on, the charge stored in capacitor 9 is discharged through transistor 501.

FIG. 4(b) shows the transistor 5 during charging and discharging.
01 collector' voltage waveform is shown.

The time constant when charging the capacitor 9 is
is determined by the capacitance of the capacitor 10 and the values of the resistors 503 and 504. Therefore, if the capacitance of the capacitor 10 changes due to a change in the dielectric constant based on a change in the medium, the charging time constant also changes. Become.

That is, for example, if the collapse has not occurred in the face 8, the charging waveform will be as shown by the solid line in FIG. 4(b), but if the collapse has occurred, the dielectric constant ε will be In other words, the capacitance of the capacitor 11 becomes small, so the above time constant becomes small, and therefore the above charging waveform becomes as shown in the same figure (
b) - as shown by the dotted chain line.

The collector voltage of the transistor 501 is determined by the comparator 50
5 is input. The comparison unit 505 compares the collector voltage with the preset voltage V ref' from the time when the output pulse of the oscillation unit falls, and as shown in FIG. A signal of logic level "1" is output until reaching the logic level "1". Therefore, when a collapse occurs, the time during which the comparator 505 outputs the signal "1" becomes shorter.

The charging/discharging section 5B for the capacitor 10 also has the same configuration as the above-mentioned charging/discharging section 5A, and the same elements as those shown in the charging/discharging section 5A in this charging/discharging section 5B are denoted by dashes.

The processing section 506 calculates the difference ΔT between the time width of the output signal of the comparison section 505 and the time width of the output signal of the comparison section 505', and outputs an analog signal corresponding to the absolute value of this difference ΔT. This analog signal is then sent to block 50
7 as a Y-axis input signal.

Now, assuming that the face 8 has collapsed as shown in FIG. 1, and the electrode 3 is located above and the electrode 4 is located below, the charging characteristics of the capacitors 9 and 10 are, for example, The results are as shown by the -dotted chain line and solid line in Figure 4 (b). Therefore, the time width difference ΔT shown in FIG.

By the way, the output signal of the rotational position detector 6 is, for example, the rotation of the head 2 with respect to the position of the cutter head 2 when the electrode 3 is positioned on the head of the cutter head 2 as shown in FIG. This shows the position (rotation angle) of the electrode 3,
This shows the rotational position of 4.

The output signal of the position detector 6 is applied to the block 507 as an X-axis input signal, so a signal waveform indicating collapse is recorded on the recording surface of the plotter 507 as shown in FIG. You can know when a collapse has occurred. Furthermore, it can be known from the angle display of the X-axis that collapse has occurred at the upper side of the cutter head 2.

Note that the waveform shown at the 180° position shows the state of detection of collapse when the electrode 4 side is positioned upward due to the rotation of the head 2.

In the above embodiment, two electrodes 3 and 4 are provided on the cutter head 2 to form the two capacitors 9 and 10, and abnormalities such as collapse are detected based on the difference in permittivity ε and ε' in each capacitor. are doing. Therefore, disturbances such as changes in soil quality and drift of the detection circuit are canceled, thereby making it possible to detect abnormalities with extremely high accuracy.

Note that it is naturally possible to detect an abnormality based on the ratio of the dielectric constants ε and ε', and even in this case, the influence of the disturbance can be removed.

Of course, the present invention can also be implemented by providing only the electrode 3 or 4 on the cutter head 2, and in this case, the detection section 5B or 5A is naturally unnecessary. And in this case,
The period of the abnormal waveform recorded on the plotter 507 is 360"
become.

Further, the present invention is applicable not only to the detection of collapse but also to the detection of water veins and cavities.

Note that it is also possible to operate alarm means such as a buzzer or a lamp when an abnormality is detected based on the output signal of the processing unit 506.

Further, in the embodiment described above, a skin plate is used as the opposing electrode of the capacitors 9 and 10, but it is also possible to use only the ground line of the detection circuit 5 as this electrode.

〔Effect of the invention〕

According to the present invention, which detects an abnormality in the face portion based on the inductivity of the soil, the above-mentioned abnormality and the position of the abnormality can be detected simply and accurately by simply providing an electrode on the cutter head. According to the present invention, the problems of conventional methods 1) to iv) described above can be solved.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an embodiment of the method according to the present invention,
FIG. 2 is an enlarged sectional view showing how electrodes are arranged with respect to the cutter head, FIG. 3 is a circuit diagram illustrating the configuration of the detection circuit, and FIG. 4 is a time chart showing the operation of the detection circuit. DESCRIPTION OF SYMBOLS 1... Shield excavator, 2... Cutter head, 3° 4... Electrode, 5... Detection circuit, 6... Rotation position detector, 8... Face portion, 9, 10.・Capacitor, 5
05゜505'... Comparison section, 506... Processing section, 5
07...Block. Figure 1 Figure 2

Claims (2)

[Claims] (1) A face part in a shield excavator characterized in that an electrode is disposed on the outer periphery of the front surface of the cutter head in the shield excavator, and abnormalities in the face part are detected based on the dielectric constant between this electrode and a counter electrode. Anomaly detection method. (2) An electrode is placed on the outer periphery of the front surface of the cutter head in the shield excavator, and the rotational position of the cutter head is detected, and abnormalities in the face are detected based on the dielectric constant between the electrode and the opposing electrode. and detecting the position of the abnormality based on the rotational position.