JPS59102110A - Strain gage type inclinometer - Google Patents

Abstract

PURPOSE:To provide excellent durability and to detect a minute slant angle highly sensitively, by holding a strain yielding plate at the holding part at the top end of a pendulum part, which is supported by a fixed part, and making the strain to be yielded in the strain yielding plate by the movement of the pendulum in correspondence with the slant angle. CONSTITUTION:A weight holder 12 of a pendulum part 2 is supported by a fixed part 1 of an inclinometer through a bearing 15 by parallel pin 14. A weight 13 is connected to the lower part. A strain yielding plate 6 is coupled into a forked holding part 17 at the upper end. The plate 6 is held by a screw 18 in a point contact mode. When a fixed part 1 is placed on a material to be measured having a slant angle theta, the pendulum part 2 is moved so that the vertical direction is kept. The strain yielding plate 6 is pushed by the screw 18 and deflected and the strain is yielded. Then the resistance value of a strain gage 7 is changed, and an electric signal corresponding to the slant angle theta is obtained. Therefore, durability is made excellent and a minute slant angle can be detected highly sensitively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strain gauge type inclinometer that is installed in structures such as retaining walls and buildings, or underground, to measure deformations thereof with high sensitivity.

Monitoring these deformations based on changes in slope angle is extremely important for construction management during construction and for safety management after construction. Therefore, it is important to accurately measure minute changes in slope angle over a long period of time. It is desired that an inclinometer that can obtain

There are various methods for detecting such minute inclination angles, including strain gauge type, differential transformer type, servo type, and electromagnetic sensor type. Various devices using these methods have been proposed and It is put into practical use. However, each of these methods has its advantages and disadvantages, and the strain gauge method, which is excellent in terms of temperature characteristics, linearity, long-term stability, and responsiveness, also suffers from distortion due to overtilt (equivalent to overload of a load cell, etc.). It had major drawbacks, such as the parts being easily destroyed and the output being weaker than other methods.

The general structure of the detection section of a conventional strain gauge type inclinometer is shown in, for example, Japanese Patent Publication No. 44-20200, Figure 3 (a).
and (b), the upper end is connected to the fixed part (
A strain gauge is attached near the fixed part of a strain plate in the form of a cantilever beam (so-called cantilever) with a weight fixed to the lower end. When this occurs, a bending moment is generated in the strain plate due to the component force of the weight, and the strain gauge is configured to detect changes in the strain on the surface of the strain plate caused by this bending moment.

The conventional strain gauge type inclinometer configured in this way is
The more sensitively we try to detect minute inclinations, the longer and thinner the strain plates have to be, and the heavier the weights become. There were drawbacks. Therefore, in order to prevent damage due to excessive inclination, some devices are provided with a stopper and have a structure in which the stopper acts against excessive inclination.

Further, an improved inclinometer using a cantilever-shaped strain plate is disclosed in Japanese Patent Publication No. 54-4870. This conventional inclinometer uses a combination of a heating wire or electromagnet that operates in conjunction with the opening and closing of an external power source and the elasticity of a spring, and a rotatable rotating body (gear) attached to a strain plate and the spring. It has a mechanical part that joins the supported fixed part, and is capable of detecting an inclination angle smaller than the angle between the inclinometer and the vertical line with high sensitivity based on that orientation, regardless of the buried orientation of the inclinometer. This is what I did.

However, this latter type of inclinometer has the same problems as the former, as well as requiring electromagnets, gears, and other mechanical mechanisms as mentioned above, making the structure complex and expensive. However, it was not possible to obtain satisfactory performance in terms of performance, etc.

In all of the above-mentioned conventional examples, since the weight is placed at the strain-generating part, the strain-generating part is weak, and a particularly big drawback is that when the inclinometer is turned upside down, the strain-generating part buckles. For example, even if it is a portable type like an insertion type inclinometer or a fixed type, it is often accidentally turned upside down and broken during installation, and the axial displacement of the strain-generating part It was very difficult to solve this problem by providing an axial stopper because of the small size. Furthermore, during the manufacturing process of the inclinometer, care must be taken when placing weights on the strain-generating part (1).During use, tension is always generated in the strain-generating part due to the weight, and this tension affects the deflection characteristics of the strain-generating part. It is not suitable for long-term use because it changes easily and has limited durability.

The present invention was made in view of these drawbacks, and its objectives are, firstly, to provide a highly durable inclinometer in which the deflection characteristics of the strain-generating portion are stable over a long period of time; Second, to provide an inclinometer that can detect minute angles of inclination with high sensitivity; third, to provide an inclinometer that has a simple structure and is easy to manufacture; and fourth, to provide an inclinometer that can easily measure the required measurement range. We are pleased to provide an inclinometer that can be designed to

Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 (Shu and H are longitudinal and cross-sectional views of main parts of an embodiment of the present invention.

The inclinometer in the figure is roughly divided into a fixed part 1 that tilts integrally with the object to be measured such as a structure or underground, and a pendulum part 2 that is pivoted at one end on the fixed part 1 and maintains a vertical direction at all times. be done.

The strain plate holder 3 as the fixed part 1 and the intermediate holder 4 are connected by screws, and the entire inclinometer is housed in a cylindrical case S shown by a two-dot chain line, and the intermediate holder 4 is fixed to the case 5. be done. The strain plate holder 3 is for holding a strain plate 6 for detecting the inclination of the object to be measured, and has a flange-like portion and a protrusion, and a plate-shaped strain plate is attached to the protrusion. Holds 6. A strain gauge 7 is attached to the strain plate 6.
Although not shown, the lead wire connected to the strain gauge 7 is connected to an airtight terminal provided on the strain plate holder 3, and its output signal is led out to the outside via the airtight terminal. Ru. O-rings 8, 9, and 10 for sealing are inserted between the itch holder 3 and the 40 intermediate holders, and between the intermediate holder 4 and the case 5, respectively. The hollow part 1 inside the intermediate holder 4 and inside the case 5
1 is filled with a damping material such as silicone oil.

The pendulum part 2 includes a cylindrical weight holder 12 inserted from the other end side of the hollow part 11 of the intermediate holder 4, and a weight 1.
It consists of 3. The weight holder 12 is pivotally supported via a bearing 15 by a parallel pin 14 fitted into the other end of the intermediate holder 4. A threaded portion 16 for joining the weight 13 is formed at one end, and a threaded portion 16 is formed at the other end. are formed into a bifurcated shape and form a holding portion 17. The other end of the deformable plate 6, one end of which is fixed to the deformable plate holder 3-, is inserted into the middle of the bifurcated part of the clamping part 17 without contacting it, and forms the clamping part 17. Both sides of the strain plate 60 are held in place by a set screw 18 so as to be in contact with each other at a point. Note that a small gap is provided between the push screw 18 and the strain plate 6 in order to prevent an increase in frictional force.

Here, the intermediate holder 4 has an inspection hole 19 for checking the clamping state of the strain plate 6, and a push screw 18 for adjusting the position relative to the strain plate 6 by turning it with a screwdriver-like tool, for example. An adjustment hole 20 is provided. Further, the parallel pin 14 is fixed to the intermediate holder 4 by a snap ring 21, and the spacer 22 is fixed to the bearing 15.
It is inserted between the inner race of the intermediate holder 4 and the lower inner wall of the intermediate holder 4, and plays the role of regulating the movement of the bearing 15 along the parallel pin 14.

Next, to explain the operation of the inclinometer configured in this way, when the object to be measured is tilted by a certain angle of inclination θ, both the fixed parts 1 installed on the object to be measured are tilted at the same angle as the inclination angle θ. On the other hand, the pendulum part 2 pivotally supported by the fixed part 1 is
Since the weight 13 works to maintain the vertical direction, the strain plate 6 whose one end is fixed to the strain plate holder 3 is screwed into the bifurcated part of the clamping part 17 extending upward from the pendulum part 2. It is pushed and bent by one of the set screws 18. The strain generated in the strain plate 6 changes the resistance value of the strain gauge 7 attached thereto, so if the strain gauge 7 is used to form a Wheatstone bridge, for example, an electric signal corresponding to the inclination angle θ can be generated. Obtainable.

FIG. 2(A) is an enlarged sectional view of the clamping part 17 that clamps the strain plate 6 in the above embodiment, and FIG. 2(B) shows the inclination angle θ and strain of the object to be measured in the embodiment It is a graph showing the relationship with the output voltage eO from the gauge 7.

In the same figure (B), some hysteresis appears because friction occurs between the tip of the push screw 18 and the strain plate 6, and tensile or compressive stress is applied to the strain plate 6 in addition to bending. However, since the weight 13 is not directly suspended on the strain plate 6, it can be formed quite thin and long, so that a highly accurate output can be obtained in the straight line portion. Here, n indicates a nut for fixing (locking) the push screw 18 after adjustment.

FIG. 3 shows another embodiment, in which the holding portion 17
It is a sectional view showing a modification of . In the same figure (A), the tip of the push screw 18' has a V-shaped cross section, and a steel ball 24 is inserted between the push screw 18' and the strain plate 6 with a small gap. ing. Since the steel ball 24 rotates along with the movement of the strain plate 6, the friction is extremely small compared to sliding. Figure CB) shows the inclination angle θ of the object to be measured and the output voltage eo from the strain gauge in this example.
FIG. By making the clamping portion 17' that clamps the strain plate 6 have a structure with less frictional parts as shown in FIG. Hysteresis can be almost eliminated. Furthermore, if the tip of the push screw 18 shown in FIG. Even if the machining of the strain plate 14 is rough, it is possible to almost eliminate twisting of the strain plate 6 during tilting, and it is possible to perform tilt measurement with extremely stable linearity.

The strain gauge type inclinometer constructed as in the above embodiment has a simple structure and an intermediate holder 4 as a fixed part 1.
Since the clamping part 17 for transmitting the tilting force of the strain plate 6 and the weight 13 to the strain plate 6 is housed inside, the outer diameter of the inclinometer itself can be made thinner, and therefore, for example, it is possible to make the inclinometer itself thinner. This is extremely convenient when inserting the inclinometer into a guide pipe buried underground, such as a type inclinometer, to measure the inclination angle for each section.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit thereof.

For example, in the embodiment, the holding part 17 is
Although an example is shown in which the weight 13 is extended to the opposite side, it is also possible to install it on the lower end side of the weight 13 (in the figure) and extend the fixing part 1, or to attach one end of the strain plate to the case 5 that is integrated with the fixing part 1. may be fixed, and the other end of the strain plate may be inserted into the forked portion of the holding portion.

Further, instead of the push screw 18 or the steel ball, two ball bearings may be attached to the forked portion of the holding portion 17, and both sides of the deformable plate 6 may be held between the ball bearings.

Also, as a stopper means to prevent the inclinometer from over-tilting,
A stopper screw that can be adjusted inwardly from the case 5 side may be provided, or a cylindrical deflection limit member having a predetermined diameter may be fitted inside the case 5 so as to be movable in the axial direction. However, such a means may be used to press down and fix the weight 13 during transportation.

As described in detail above, according to the present invention, it is possible to provide an inclinometer that has a number of advantages described below compared to conventional strain gauge type inclinometers.

First, because the weight of a pendulum or weight is not directly applied to the strain plate that senses the inclination of the object to be measured, the deflection characteristics of the strain plate are stable over a long period of time, and it is highly durable. The plate can be made thinner and a highly sensitive inclinometer can be obtained.

Second, since the length of the pendulum is sufficiently longer than the length of the strain plate, the inclination angle of the object to be measured can be magnified and transmitted to the strain plate. It is possible to detect minute inclination angles with high sensitivity, and by changing the lengths of the strain plate and the pendulum part, it is possible to easily design and manufacture a measurement range similar to that of a floor desk.

Fourthly, since the inclinometer of the present invention can use a pendulum part including a weight that does not buckle, the inclinometer can be tilted so that it does not break even if the inclinometer is turned upside down by providing a stopper means for preventing excessive inclination. It can be used as a total.

[Brief explanation of the drawing]

FIG. 1 (Shu and B) is a vertical cross-sectional view and a cross-sectional view showing the configuration of an embodiment of the present invention, and the second section is an enlarged cross-sectional view of the strain plate and the clamping part, which are the main parts in FIG. 1. , same figure (B)
3(A) is an inclination angle-output voltage characteristic diagram of the embodiment shown in FIG. 3(A), FIG. A tilt angle-output voltage characteristic diagram in the example shown in (A) is shown. 1... Fixed part, 2... Pendulum part, 3
......Strain plate holder, 4...Intermediate holder, 5...Case, 6...Strain plate, 7...Strain gauge , 8-10...
...0 ring, 12... Weight holder, 1
3... Weight, 17, 17'...
Holding part, 18, 18'...Press screw, Sae・
·····wrecking ball. Figure 2 (A) CB) Figure 3 (A) (B)

Claims (4)

[Claims] (1) In an inclinometer installed in a structure or the ground to measure deformation thereof, a fixed part that slopes integrally with the object to be measured such as the structure or ground, and 3. One end of the fixed part is attached to the fixed part. a pendulum part that is supported by a shaft and always maintains a vertical direction; a strain plate to which a strain gauge is attached and one end fixed to the fixing part; and a strain plate extending integrally from the pendulum part and sandwiching both sides of the other end of the strain plate. 1. A strain gauge type inclinometer, comprising a two-pronged clamping part disposed so as to be inserted therein, and configured so that the inclination of the object to be measured is detected by the strain gauge. (2) The holding portion is configured to hold both sides of the strain plate by two push screws screwed into the bifurcated portions, respectively. Strain gauge type inclinometer. (3) The strain gauge type inclinometer according to claim 2, wherein steel balls are inserted between the tips of the two push screws and the strain plate, respectively. (4) The strain gauge type incline according to claim 1, wherein the clamping part has two ball bearings in the forked part and is configured to clamp the strain plate from both sides by these bearings. Total.