JP3407009B2 - Earth pressure gauge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a structure of an earth pressure gauge,
In particular, the present invention relates to a structure of an earth pressure gauge that is attached to the tip of an excavator that is excavating in a tunnel and that is used to measure excavation soil pressure during the operation.

[0002]

2. Description of the Related Art When excavating Tonuel on a hillside or seabed soil, the rotary excavating blade attached to the tip is rotated to dig into the soil. In this case, in order to control the traveling operation of the excavator, an earth pressure gauge is provided at the tip of the rotary excavating blade to constantly measure the pressure of earth and sand in front of the excavation.

As an earth pressure gauge which has been conventionally used, for example, the one described in JP-B-62-32412 can be mentioned. This earth pressure gauge has a structure in which a cylindrical case is projected from the board attached to the tip of the excavator to a cylindrical board in the earth surface direction, and a cup-shaped pressure receiving plate is placed inside the case, and its mouth is placed inside. And slide it freely. On the other hand, in the center of the cylindrical case,
A strain tube is erected from the substrate. This strain tube is also formed in a deep cup shape, the cylindrical side wall is thick and has rigidity, and its mouth is fixed to the substrate. The bottom portion of the strain-flexing cylinder is formed thin, and the bottom portion faces the bottom portion of the pressure receiving plate, and they are connected by a screw rod. A strain gauge is attached to the bottom of the strain-flexing cylinder. The pressure plate is directed toward the soil surface and attached to the excavator to excavate the soil. During operation, when the pressure plate receives pressure from the soil surface, it retracts in the cylindrical case.
This retracting force is transmitted from the screw rod to the bottom of the strain-flexing cylinder, and this portion is deformed in proportion to the earth pressure, and this deformation is detected by a strain gauge to measure the earth pressure.

[0004]

In the conventional earth pressure gauge as described above, since the bottom portion of the pressure receiving plate and the bottom portion of the strain-flexing cylinder are connected by one screw rod, the earth pressure can be accurately measured against the strain. The accurate earth pressure cannot be measured unless the mechanical precision of each part is improved in order to transmit to. Further, since the conventional one has the above-mentioned configuration, in order to minimize the measurement error due to the eccentric load, etc., these shapes are complicated, and there is a problem in reproducibility in mass production. There is. In addition, the strain gauge installation area is small and narrow, resulting in poor sensitivity and poor accuracy.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional inconveniences, and an object thereof is to accurately measure earth pressure without increasing the mechanical assembly precision of the earth pressure gauge. To provide an earth pressure gauge capable of producing an earth pressure gauge having the same characteristics with high reproducibility and high sensitivity without requiring precise adjustment. is there.

[0006]

In order to solve the above-mentioned problems, according to the present invention, an earth pressure gauge for detecting the pressure received from earth and sand by the strain amount of a strain gauge is the same as the inner shape of a cylindrical main body case. A mounting base having an outer shape, a thin pressure detecting section formed inside the mounting base, a pressure receiving section having the same outer shape as the inner shape of the cylindrical main body case, the pressure receiving section and the pressure detecting section are connected to each other. The pressure receiving unit has a coupling unit having a cross section smaller than that of the pressure receiving unit and includes a pressure receiving unit formed of a metal block integrally formed with these units, and a strain gauge provided in the pressure detecting unit. There is provided an earth pressure gauge characterized by being fixed to a substrate in a case body. The strain gauge is characterized in that it is arranged in the cavity pressure detection portion formed by the mounting base portion and the pressure detection portion. A plurality of strain gauges are arranged in the pressure detection unit. The strain gauges attached to the inside of the cavity are characterized by being arranged on lines orthogonal to each other with the center point of the pressure detection unit as the center. The main body case has a cylindrical shape.

[0007]

When the pressure such as earth and sand is applied to the pressure receiving portion, the pressure receiving portion is recessed along the axis of the case body, and the pressure detecting portion is curved. This strain is transmitted to the strain gauge and taken out from the cable as an electric signal to the outside.

[0008]

An embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of an earth pressure gauge according to the present invention, and FIG. 2 is a bottom view thereof. In these figures, 1
Is a disk-shaped substrate, and mounting holes 2 are formed at four positions. A cylindrical case body 3 is fixed to the substrate 1 by means such as welding. A pressure receiving element 4 is arranged inside the case body 3. The pressure receiving element 4 is
As shown clearly in FIG. 3, the flat cylindrical pressure receiving unit 5
Have. The pressure receiving section 5 is arranged inside the case body 3. An O-ring 7 is fitted in the depression 6 on the side of the pressure receiving portion 5, and the O-ring 7 is interposed between the case body 3 and the pressure receiving portion 5 to prevent the intrusion of earth and sand. .

The pressure-receiving element 4 also has a ring-shaped mounting base 8. The mounting base 8 has a mounting hole 9 for mounting on the substrate 1. Then, as shown in FIG. 1, the pressure receiving element 4 is attached to the substrate 1 in the case body 3 with the screw 10. A thin pressure detecting portion 11 is formed on the inner surface of the mounting base portion 8, and a columnar connecting portion 12 is formed in the center thereof. The connecting portion 12 includes the pressure receiving portion 5 and the pressure detecting portion 11. Are combined with. Pressure detector 1
Since 1 is formed thin, a cavity 13 is formed inside the mounting base 8. A strain gauge 14 is attached to the back side of the pressure detection unit 11. As shown in FIG. 4, a total of eight strain gauges 14 attached in the cavity 13 are arranged on a line orthogonal to each other with respect to the point O. These strain gauges 14 are connected in series so as to face each other around the point O, and a bridge circuit is formed as shown in FIG. The pressure receiving portion 5, the coupling portion 12, the pressure detecting portion 11, and the mounting base portion 8 that form the pressure receiving element 4 are integrally formed by cutting from an integral metal block.

As shown in FIG. 1, a through hole is provided in the center of the substrate 1, a terminal plate 15 is provided inside the through hole, and the input end and the output end of the bridge circuit shown in FIG. Derive to. A cover 16 is attached to the back surface of the substrate 1 with screws 17. 18 is an O-ring, cover 1
The inside of 6 is kept airtight. An electric wire penetrating piece 19 is attached to the center of the cover 16, and the cable 20 is hermetically introduced into the cover 16 and connected to the terminal plate 15 to lead out an electric signal obtained from the bridge to the outside.

The earth pressure gauge configured as described above is attached to the tip of the device. When the pressure such as earth and sand is applied to the entire surface of the pressure receiving portion 5 in the vertical direction, the pressure receiving portion 5 is recessed along the axis L of the case body 3 to bend the pressure detecting portion 11. This strain is transmitted to the strain gauge 14,
The electric signal is taken out from the cable 20 to the outside.
Since the outer diameter of the mounting base 8 is substantially the same as the inner diameter of the case body 3 and is large, the inner diameter of the cavity 13 can be large. Therefore, since the area of the pressure detecting portion 11 can be made large, the strain region of the portion can be made large, and as a result, the area for attaching the strain gauge 13 also becomes large and the sensitivity also increases.

Even if the pressure such as earth and sand is applied to the pressure receiving portion 5 in a cantilever manner, the pressure receiving portion 5 descends vertically along the case body 3, so that the pressure detecting portion 11 operates in the same manner as described above. The strain and strain gauge 14 accurately detect the earth pressure.

Although the present invention has been described with reference to the above-mentioned embodiments, various modifications and applications are possible within the scope of the present invention, for example, changing the cross-sectional shape of the case body from a cylinder to a polygon. These modifications and applications are not excluded from the scope of the present invention.

[0014]

As described in detail above, according to the present invention, since the outer shape of the mounting base is substantially the same as the inner diameter of the case body and is large, the inner shape of the cavity can be large. Therefore, since the area of the pressure detecting portion can be made large, the strain region of the portion can be widened, and as a result, the area for mounting the strain gauge also becomes large and the sensitivity also increases. Also, since the entire pressure receiving element is integrally molded from a metal block,
It is possible to measure the earth pressure accurately without increasing the mechanical accuracy of the earth pressure gauge, and it is possible to manufacture the earth pressure gauge having the same characteristics with good reproducibility without requiring precise adjustment.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an earth pressure gauge according to the present invention.

FIG. 2 is a bottom view of the earth pressure gauge according to the present invention.

FIG. 3 is a sectional view of a pressure receiving element.

FIG. 4 is a bottom view of the pressure receiving element.

FIG. 5 is a connection circuit diagram of a strain gauge.

[Explanation of symbols]

1 ... Board 2 ... Mounting hole 3 Case body 4 ... Pressure receiving element 5 ... Pressure receiver 6 ... hollow 7-O-ring 8: Mounting base 9: Mounting hole 10 ... Screw 11 ... Pressure detector 12 ... Coupling part 13 ... Cavity 14: Strain gauge 15-Terminal board 16 ... Cover 17 ... Screw 18-O-ring 19: Wire penetration hardware 20 ... Cable

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01L 5/00 G01L 1/00

Claims (5)

(57) [Claims] 1. An earth pressure gauge for detecting a pressure received from earth and sand by a strain gauge strain amount, comprising: a mounting base portion having the same outer shape as an inner shape of a cylindrical main body case; and a thin wall-shaped member formed inside the mounting base portion. The pressure detecting unit and the pressure receiving unit having the same outer shape as the inner shape of the tubular main body case, the pressure receiving unit and the pressure detecting unit are coupled to each other, and the pressure receiving unit has a coupling section having a cross section smaller than that of the pressure receiving unit. An earth pressure gauge, comprising: a pressure receiving unit formed of a metal block; and a strain gauge provided in the pressure detecting unit, wherein an attachment base of the pressure receiving unit is fixed to a substrate inside the case body. 2. The earth pressure gauge according to claim 1, wherein the strain gauge is arranged in a cavity pressure detecting portion formed by the mounting base portion and the pressure detecting portion. 3. The earth pressure gauge according to claim 1, wherein a plurality of strain gauges are arranged in the pressure detection unit. 4. The earth pressure gauge according to claim 3, wherein the strain gauges adhered in the cavity are arranged on lines orthogonal to each other with the center point of the pressure detection unit as the center. 5. The earth pressure gauge according to claim 1, wherein the main body case has a cylindrical shape.