JP2008216227A - Inclinometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inclinometer suitable for using by inserting, for example, into a bored hole (vertical hole) excavated under the ground by boring and having excellent detection linearity. <P>SOLUTION: This inclinometer includes a bar-like movable element so installed in a cylindrical case as to be moved forward and backward in the axial direction, a differential transformer having a displacement sensor for detecting the displaced amount of the movable element such as a magnetic permeable body fitted to the movable element or a metal core producing eddy current effect and a coil so installed as to surround the core, a rotating body having a rotating shaft in the direction transverse to the axial direction of the case and rotatably supported on the inside of the case, a weight fitted to the rotating body and biasing the attitude of the rotating body in the direction of the gravity of the earth, a spring fitted to the rotating body and elastically biasing the attitude of the rotating body, and a motion converting mechanism for converting the rotating motion of the rotating body due to the inclination of the case into the linear motion of the movable element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inclinometer suitable for use by being inserted into a boring hole (vertical hole) excavated in the ground by boring.

  In order to prevent landslide disasters such as landslides, it is necessary to take measures by measuring the slope of the strata, for example. By the way, the strata constantly change under the influence of vibrations caused by earthquakes, moisture in the ground, and pressure applied from the ground surface, etc. An inclinometer is used as one of the methods to measure such strata movement. It is done. An inclinometer basically uses the fact that a weight suspended by a thread, a rod, etc. always hangs down in the direction of the earth's gravity, that is, in the vertical direction. The tilt angle (tilt angle) of the substrate is determined from the angle formed by the direction of the movement (see, for example, Patent Documents 1 and 2).

In particular, an inclinometer for measuring the movement of the formation is usually used by being embedded in a sealed case and buried in the ground together with the case so as to measure the inclination angle of the case that changes with the movement of the formation. Configured.
JP 2003-139530 A JP-A-10-141950

  By the way, when this kind of inclinometer is used by being inserted into a boring hole (vertical hole) excavated in the ground by boring, for example, it is common to use a cylindrical body (pipe) having a diameter that can be inserted into the boring hole as the case. It is. And, it is extremely desirable from the viewpoint of construction cost and work that the diameter of the case is as small as possible, for example, the diameter of the boring hole can be reduced. In addition, since the ground is highly humid and may get wet, the tilt sensor is not a hall element or strain gauge, but has a sealed and strong structure that is not easily affected by the external environment such as water and pressure. It is preferable to use a differential transformer.

  In general, the inclinometer detects the inclination of the weight in the horizontal plane with respect to the case (base) as described above. Therefore, as shown in Patent Documents 1 and 2, a differential transformer is used as a sensor for detecting the inclination. It must be placed sideways. However, there is a problem in how to incorporate such a differential transformer into a cylindrical body (pipe) that can be inserted into a boring hole having an outer diameter of about 30 mm, for example.

  That is, the outer diameter of the differential transformer (coil) is generally as small as about 10 mm, but its overall length is long. For this reason, when the differential transformer is installed sideways in a cylindrical pipe, the diameter of the pipe cannot be denied. For example, the length of the coil of the differential transformer with a measurement distance of ± 1 mm is about 20 mm. When the core is included, the total length is about 30 mm, so the inner diameter of the pipe needs about 35 mm. Then, since it is necessary to dig a large diameter of the borehole, a great excavation cost is required.

  Further, a conventional inclinometer configured to measure a tilt displacement of a heavy weight with a differential transformer, for example, a weight (about 100 g) is suspended by a single leaf spring, and the weight is caused by the gravity of the earth along with the inclination. It is configured to measure the lateral displacement that occurs when moving in the vertical direction against this force with a differential transformer. However, since the force acting on the weight is large when the case (pipe) is inclined, there is an advantage that it operates reliably even if there is some friction, but there are the following drawbacks.

  That is, since the differential transformer is installed in the lateral direction, the diameter of the case pipe increases. The lateral displacement of the weight suspended by the leaf spring is not an accurate linear motion, but draws an arc, so it is very difficult to set the positions of the core and the coil of the differential transformer accurately. Further, since it is necessary to make a large gap between the core and the coil, the characteristics of the differential transformer deteriorate. Furthermore, the component force of the surface perpendicular to the bending surface of the leaf spring causes the leaf spring to be twisted, and the linearity of the leaf spring is deteriorated. In addition, the elastic value of the leaf spring is constant when a certain amount of load is applied, but it is not constant when the load is close to no load. Therefore, it is difficult to obtain a good linearity near the zero point. There is.

The present invention has been made in consideration of such circumstances, and its purpose is suitable for use by inserting into a boring hole (longitudinal hole) excavated into the ground by boring, for example, and performance with particularly good linearity. It is to provide an inclinometer with.
That is, the inclinometer according to the present invention can use a case having a smaller diameter (inner diameter is 20 to 25 mm), and is used by being inserted into a boring hole (vertical hole) excavated in the ground by boring, for example. Therefore, an object is to provide an inclinometer having a small outer diameter suitable for insertion into a hole having a smaller diameter than that of a conventional bore hole. In particular, an object is to provide an inclinometer capable of detecting an inclination with good linearity.

In order to achieve the above-mentioned object, the inclinometer according to the present invention is incorporated in a cylindrical case and embedded in the ground together with the case, and is suitable for measuring the inclination of the case,
<a> a mover provided to be movable forward and backward in the axial direction of the case;
<b> A displacement sensor for detecting the displacement of the mover, for example, a magnetically permeable body mounted on the mover, or a core made of a metal that produces an eddy current effect, and a coil provided surrounding the core A differential transformer,
<c> a rotating body having a rotating shaft in a direction crossing the axial direction of the case and rotatably installed inside the case;
<d> a spring that elastically biases the rotating body and supports it in a direction orthogonal to the axial direction of the case;
<e> a weight attached to the rotating body and biasing the rotating body in the direction of gravity against the spring;
<f> A motion conversion mechanism that converts the rotation of the rotating body according to the inclination of the case into a linear movement of the mover is provided.

  That is, the inclinometer according to the present invention attaches a weight to a rotating body supported by a bearing (for example, a ball bearing) that has low friction and is strong and rotates only on one axis surface, and is provided on both sides of the rotating body. It is suspended by a pair of springs (for example, vine springs). When the case is tilted, the weight moves in the vertical direction of the earth by gravity against the rotational force generated by the two vine springs. The rotational displacement of the rotating body caused by the above is measured with a differential transformer.

  According to the inclinometer having the above-described configuration, the rotating body is elastically biased by a spring and is balancedly supported in a direction orthogonal to the axial direction of the case, and the rotating body is counteracted by the weight against the spring. Therefore, the amount of movement of the mover accompanying the rotation of the rotating body can be easily adjusted to the measurement range of the displacement sensor. Therefore, it is possible to detect the tilt angle with good linearity.

  In addition, the rotation of the rotating body, which is tilted with respect to the case of the rotating body whose posture is held constant in the gravity direction of the earth by the weight, is provided so as to be able to advance and retract in the axial direction of the cylindrical case via a motion conversion mechanism. Therefore, even when the horizontal width (diameter) of the cylindrical case cannot be sufficiently secured, the displacement of the movable element and, consequently, the rotational angle of the rotating body can be reliably detected. It becomes possible to do.

Hereinafter, an inclinometer according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing a schematic configuration of an inclinometer according to an embodiment of the present invention, and FIG. 2 is a side configuration diagram thereof. This inclinometer is incorporated into a cylindrical case 1 having an inner diameter of 20 to 25 mm, for example. Specifically, the inclinometer is mounted on a support body 2 made of a long plate and incorporated in the inside of the case 1, and is inserted integrally with the case 1 into a boring hole (not shown) previously drilled in the ground. To be used embedded in the ground.

  The inclinometer generally includes a movable element 3 made of a shaft body having a predetermined length in an upper region of a support body 2 made of a long rectangular plate inserted along the axial direction of the case 1. In addition to being provided so as to be able to move straight along the longitudinal direction of the support 2, a differential transformer (displacement sensor) 4 for detecting the vertical displacement of the mover 3 is provided. The differential transformer 4 includes a cylindrical coil 4b that is attached to the tip of the movable element 3 and surrounds a cylindrical core 4a made of, for example, a magnetic material or a metal that produces an eddy current effect. A displacement amount of the core 15 relative to the coil 4b is detected as an inclination angle of the case 1 from an induced voltage generated in the cylindrical coil 4b by the core 4a when the cylindrical coil 4b is excited. . The movable element 3 is supported on the upper end portion of the cylindrical coil 4b coaxially with the cylindrical coil 4b via a thrust bearing 5, thereby smoothly moving up and down in the axial direction in the cylindrical coil 4b. It comes to move.

  On the other hand, a radial bearing 6 such as a ball bearing is provided in the lower region of the support 2 with the direction orthogonal to the surface of the support 2 as an axis, and a plate-like rotating body is provided via the radial bearing 6. 7 is pivotally supported. In particular, the rotating body 7 is supported by the radial bearing 6 so that it can smoothly rotate only on one axial plane orthogonal to the axial direction of the case 1 without causing a large friction. Is provided. Further, a weight 8 of about 100 g, for example, is fixed to the lower end portion of the rotating body 7, and the rotating body 7 is rotated and deflected in the direction of gravity by the weight 8. The weight 8 rotates integrally with the rotating body 7 with the radial bearing 6 described above as a rotating shaft.

  A pair of support pins 9 a and 9 b are provided symmetrically with respect to the center line of the rotating body 7 passing through the radial bearing 6 on both shoulders of the upper end of the rotating body 7. Also, a pair of support pins 10a and 10b are provided symmetrically with respect to the center line of the support 2 passing through the radial bearing 6 on both upper shoulders of the support 2 described above. A pair of coil springs (bend springs) 11a and 11b are stretched between the support pins 10a and 10b and the support pins 9a and 9b. The rotating body 7 is basically supported in a balanced manner in a direction perpendicular to the axial direction of the case 1 by the elastic force of these coil springs (bend springs) 11a and 11b. The left-right symmetric position refers to a line-symmetric position with respect to a center line connecting the rotation center of the rotating body 7 and the weight 8 attached to the rotating body 7.

  As described above, the upper one side edge portion of the rotating body 7 that is rotatably provided and the lower end portion of the movable element 3 are connected by a link member 12 having a substantially “<” shape. ing. Specifically, one end of the link member 12 is rotatably connected to the upper one side edge of the rotating body 7 via a connecting pin 13a, and the other end is connected to the upper end of the link member 12 via a connecting pin 13b. The mover 3 is rotatably connected to the lower end portion of the mover 3. With such a connection structure, the rotational displacement of the rotating body 7 is transmitted as the vertical displacement of the movable element 3.

  According to the inclinometer having such a configuration, the above-described rotating body 7 has a structure in which the elastic force (tensile force) of the two coil springs (bend springs) 11a and 11b and the weight of the weight 6 are balanced. Posture is stable. Therefore, for example, even when the tilt measurement range as an inclinometer is ± 30 °, the rotation range of the rotary body 7 accommodated in the case 1 is only allowed to be ± 15 ° as described above. By rotating the elastic force (tensile force) of the two coil springs (bend springs) 11a and 11b and the weight of the weight 8 in advance, the rotating body 7 can be rotated with respect to the inclination of the case 1. The corner can be halved.

  That is, an elastic biasing force applied to the rotating body 7 to stably balance the posture of the rotating body 7 in the radial direction of the case 1 in a steady state, and a rotational bias in the gravitational direction on the rotating body 7. By adjusting the weight of the weight 8 that applies force, the rotation angle φ of the rotating body 7 with respect to the inclination angle θ of the case 1 can be set to satisfy a certain proportional relationship. Therefore, there is a great advantage in incorporating the above-described mechanism inside the case 1 made of a small diameter pipe.

  The present invention is not limited to the embodiment described above. Here, an example in which the differential transformer 4 is used as the displacement sensor has been described, but it is of course possible to use a potentiometer, a Hall element, or the like that slides in the vertical direction as the displacement sensor. Further, the shape or the like of the rotating body 5 may be any as long as it can accommodate the space in the case 1 effectively. Further, it is sufficient that the support structure of the rotating body 7 is smoothly rotated using a bearing such as a ball bearing, and it goes without saying that the spring is not limited to the above-described coil spring (vine spring). Yes. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

The front view which shows schematic structure of the inclinometer which concerns on embodiment of this invention. The side view of the inclinometer shown in FIG.

Explanation of symbols

1 Case 2 Support plate 3 Movable element 4 Differential transformer (displacement sensor)
7 Rotating body 8 Weight 12 Link member (connection mechanism)
11a, 11b Coil spring (bend spring)

Claims (4)

An inclinometer that is incorporated in a cylindrical case and embedded in the ground together with the case to measure the inclination of the case,
A mover provided to be movable back and forth in the axial direction of the case;
A displacement sensor for detecting the displacement of the mover;
A rotating body having a rotating shaft in a direction crossing the axial direction of the case and rotatably supported in the case;
A spring that elastically biases the rotating body and supports it in a direction orthogonal to the axial direction of the case;
A weight attached to the rotating body and biasing the rotating body in the direction of gravity against the spring;
An inclinometer comprising: a motion conversion mechanism that converts the rotation of the rotating body associated with the inclination of the case into a linear movement of the mover.   2. The inclinometer according to claim 1, wherein the motion conversion mechanism includes a link mechanism that connects the movable element and the rotating body via a connecting body so as to be capable of relative displacement.   The displacement sensor is a differential transformer composed of a magnetically permeable body attached to the mover or a core made of a metal that produces an eddy current effect, and a coil provided surrounding the core. The inclinometer according to 1.   2. The inclinometer according to claim 1, wherein the spring includes a pair of vine springs stretched between both ends of the rotating body in the horizontal direction and the case.

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