JPS6251402B2 - - Google Patents

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 by changes in slope angle is extremely important for construction management during construction and for safety management after construction. It is hoped that an inclinometer that can measure this will be developed.

There are various methods for detecting such minute angles of inclination, such as strain gauge method, differential transformer method, servo method, and electromagnetic sensor method. 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 part of a conventional strain gauge type inclinometer is that the upper end is fixed to a fixed part and the lower end is A strain gauge is attached near the fixed part of a cantilever beam (so-called cantilever) to which a weight is fixed, and when the fixed part is tilted to a certain angle of inclination, the force of the weight is applied to the cantilever beam. A bending moment is generated in the cantilever beam, and the strain gauge is configured to detect changes in surface strain caused by this bending moment.

In conventional strain gauge type inclinometers configured in this way, the more sensitively the minute inclinations are detected, the longer and thinner the cantilevers are, and the heavier the weight is. Since it had to be made large, it had the disadvantage that the cantilever beam, which is the strain-generating part, was very easy to break. Therefore, in order to prevent it from breaking due to excessive inclination, a stopper was installed.
Some have a structure in which a stopper acts against excessive inclination.

Furthermore, an improved cantilever type inclinometer is disclosed in Japanese Patent Publication No. 4870/1983. This conventional inclinometer uses a combination of a heating wire or an electromagnet that operates in conjunction with the opening and closing of an external power source and the elasticity of a spring, and a rotary body (gear) attached to a cantilever 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, the weight is suspended by a cantilever, that is, a strain-generating part, so the strain-generating part is weak, and a particularly big drawback is that when the inclinometer is turned upside down, the strain-generating part is weak. For example, even portable inclinometers such as insertion-type inclinometers, or fixed types, are often accidentally folded upside down and broken during installation, resulting in strain-generating parts. Since the axial displacement of the shaft is small, it is very difficult to solve this problem by providing an axial stopper.

The present invention has been made in view of these drawbacks, and its objectives are, firstly, to provide an inclinometer that can detect minute inclination angles with high sensitivity;
Second, to provide an inclinometer that has no mechanical contact or friction points, and therefore has good linearity, hysteresis, and repeatability; and third, to provide an inclinometer that can be easily designed and manufactured to have the required measurement range. Fourth, to provide an inclinometer that has a relatively simple structure and can be supplied in large quantities at low cost.Fifth, to provide an inclinometer that is resistant to breakage under various usage conditions.

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

FIG. 1, FIG. 2, and FIG. 3 are schematic configuration diagrams each schematically showing the configuration of different embodiments of the present invention.

The inclinometer in the embodiment shown in Fig. 1 has a fixed part 1 that tilts integrally with the object to be measured, such as a structure or the ground, and a fixed part 1 that is attached to the fixed part 1 and responds to the inclination in a certain direction (inclination angle θ). A pendulum 4 has a beam part 2 that swings, a pendulum 4 having a weight 3 attached to the other end (lower end in the figure) of this beam part 2, and a fixed part extending from the fixed part 1 to the vicinity of the weight 3 of the pendulum 4. 1, and a fixed piece 5 which is located near the weight 3 of the pendulum 4, has one end 6 fixed to the fixed piece 5 which is integrated with the fixed part 1, and the other end 7 of which is an axial displacement absorbing spring 8. A cantilever beam 9 that is connected to the weight 3 through the pendulum 4 and is sufficiently shorter than the pendulum 4.
and a strain gauge 10 attached by adhesive or other means to a position on the cantilever beam 9 where strain can be detected.
It is composed of.

Note that the beam portion 4 of the pendulum 4 has a length and cross-sectional shape (thickness, width, etc.) that will not buckle even when turned upside down.
The axial displacement absorbing spring 8 transmits the movement of the pendulum 4 to the cantilever beam 9 without friction, and also absorbs the weight due to the difference in the axial length of the pendulum 4 and the cantilever beam 9, that is, the swing radius. It is configured to absorb a relative displacement with respect to the weight 3, that is, a tensile force generated on the cantilever beam 9.

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 part 1 and the fixed piece 5 installed on the object to be measured are tilted at the same angle as the inclination angle θ. (In this case, the angle between the main axis 11 of the inclinometer and the vertical line 12), which causes the pendulum 4 (beam 2 and weight 3)
swings, and this swing of the pendulum 4 is transmitted to the cantilever beam 9 via the axial displacement absorbing spring 8, causing the cantilever beam 9 to flex. The strain generated in this cantilever beam 9 is detected by a strain gauge 10 attached thereto. The output of the strain gauge 10 responds to the inclination (inclination angle θ) of the object to be measured with high sensitivity and corresponds accurately.

Fig. 2 shows the configuration of another embodiment, and the difference from the one shown in Fig. 1 is that the one shown in Fig. 1 uses an elastic beam for the beam part 2 of the pendulum 4, and the upper end thereof is a fixed part. In contrast, in this embodiment, a rigid beam is used as the beam portion 2', and its upper end is attached to the fixed portion 1 via a hinge 13.

The device of this embodiment configured in this way may have a slight influence on the accuracy of the hinge 13 in some cases compared to the one shown in the first drawing, assuming other conditions are the same, but the inclinometer is This has the advantage of increasing sensitivity.

FIG. 3 shows the configuration of yet another embodiment, in which one end of the cantilever beam for detecting inclination is fixed not to the fixed piece 5 side but to the weight 3 side.

That is, in the figure, the cantilever beam 9' has one end 6' fixed to the weight 3, and the other end 7' connected to the fixed piece 5 via an axial displacement absorbing spring 8'.
A strain gauge 10 is attached (for example, glued) to a predetermined location on the cantilever 9'.

Even with this configuration, effects similar to those of the embodiments shown in FIGS. 1 and 2 can be obtained.

FIG. 4 is a perspective view showing the structure of yet another embodiment of the embodiment of the invention shown in FIG. 1. Note that in FIG. 4, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and the explanation thereof will be omitted.

In the figure, the fixed piece 5 is connected from the fixed part 1 to the weight 3.
The swing angle of the weight 3 is therefore regulated by the square hole 14 . That is, the portion 15 of the fixed piece 5 facing the square hole 14 functions as a stopper against excessive inclination of the pendulum 4. A screw hole 16 is provided at the upper end of the fixing part 1 for fixing it to an external protective case (not shown) or the like that slopes integrally with an object to be measured such as a structure or the ground.

FIGS. 5a to 5f are schematic configuration diagrams showing various modifications of the axial displacement absorbing spring, which is a main part of the present invention, together with their mounting manners. In FIG. 5, members (or parts) common to those in FIG. 1 are given the same reference numerals. Furthermore, although the axial displacement absorbing springs 8 have different configurations, they are given the same reference numerals.

In FIGS. 5a to 5f, the axial displacement absorbing spring 8
are each made of a thin plate spring material, and the shape is approximately a cap shape in the case of figure a, approximately a fatigue line shape in the case of figure b, an elliptical shape in the case of figure c, and a circular shape in the case of figure d. , in the case of figure e, it is formed in a heart shape, and in the case of figure f, it is formed in a deformed heart shape, and one end (the upper end in the figure) is connected to the cantilever beam 9 with a stud 17, and the other end is connected to a weight. It is attached to 3. In Figures d and e, the axial displacement absorbing spring 8 is attached to the weight 3 with a bolt 19, with a rounded washer 18 applied from the inside of the spring 8.

The necessity of using such an axial displacement absorbing spring 8 will be explained with reference to FIG. Therefore, if the other end 7 of the cantilever beam 9 is directly connected (fixed) to the weight 3, an excessive tensile force will be applied to the cantilever beam 9 due to the inclination, causing the cantilever beam 9 to break. It turns out. In order to avoid this, it is possible to incorporate a roller or the like into the weight 3 and use the roller to slide on the cantilever beam 9 to prevent excessive tensile force from acting on the cantilever beam 9. By incorporating this, hysteresis and repeatability deteriorate due to the effects of friction and play, making it impossible to expect high sensitivity and high accuracy. Therefore, if the axial displacement absorbing springs 8, 8' as in the above embodiment are interposed between the cantilever beam 9 and the weight 3 or between the cantilever beam 9 and the fixed piece 5, mechanical contact points Moreover, the axial displacement absorbing spring 8 can be considered to be an elastic body within a certain range, so that there is no adverse effect on accuracy.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be modified without departing from the gist thereof.
Of course, various changes, combinations, substitutions, etc. are possible.

For example, in FIG. 2, the upper end of the beam portion 2' of the pendulum 4 may be attached to the fixed portion 1 by using a hinge made of a flexible strip, in addition to the method shown in FIG. The upper end may be attached to the fixed part 1. By doing this,
It is possible to eliminate the mechanical friction part and eliminate the adverse effect of the hinge on accuracy, and it is also possible to increase the sensitivity of the inclinometer compared to the one using an elastic beam like the one shown in the first figure.

Moreover, the beam part 2 shown in FIG.
It may also be attached to the weight 3.

Also, the rivets 17 may not be used as the means for attaching the axial displacement absorbing spring 8 to the cantilever beam 9, and spot welding or brazing may be used.

Alternatively, the inclinometer may be housed in a case and a damping material such as silicone oil may be filled inside the case to reduce noise components caused by high frequency vibrations and the like.

Furthermore, as a stopper means for preventing over-inclination of the inclinometer, an example (Fig. 4) is shown in which the fixed piece 5 is used to restrict the limit of the swing direction of the weight 3.
For example, a stopper portion may be provided in the case housing the inclinometer. Furthermore, during transportation, the pendulum 4 or the weight 3 may be fixed by being pressed against the case or the fixing piece 5 using a stopper screw or the like.

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

First, since the length of the pendulum (beam and weight) is sufficiently longer than the length of the cantilever beam, it is possible to Responds with high sensitivity to the tilt of the inclinometer. In other words, the inclinometer of the present invention can detect minute inclination angles of the object to be measured with high sensitivity.

Second, the inclinometer of the present invention has very good linearity, hysteresis, and repeatability because there are no mechanical contact points or friction points.

Thirdly, the inclinometer of the present invention can be easily designed and manufactured into a required measurement range by appropriately changing the length of the beam portion.

Fourthly, the inclinometer of the present invention is based on the above-mentioned Japanese Patent Publication No. 44
Compared to the structure of the inclinometer disclosed in Publication No. 20200, it is more complicated due to the beam part and the axial displacement absorbing spring, but these are all inexpensive members, and various other members are also used. There are many inclinometers that can be used in common with measuring ranges (that is, capacities) of , and the overall structure of the inclinometer is relatively simple and suitable for mass production, and can be supplied in large quantities at low cost.

Fifth, the inclinometer of the present invention does not support the weight with the cantilever beam to which the strain gauge is attached, but is supported with the beam of the pendulum, so it is highly sensitive and robust. be. For example, by making the beam portion long and cross-sectional so that it does not buckle, and by providing a stopper means for preventing excessive inclination, it is possible to obtain an inclinometer that will not break even if it is over-inclined or turned upside down.

[Brief explanation of the drawing]

1, 2, and 3 are schematic configuration diagrams each schematically showing the configuration of different embodiments of the present invention, and FIG. 4 is a further configuration embodying the embodiment shown in FIG. 1. Perspective views showing Figure 5 a-f
2A and 2B are schematic configuration diagrams showing various modifications of the axial displacement absorbing spring, which is a main part of the present invention, together with their mounting manners. 1... fixed part, 2, 2'... beam part, 3... weight, 4... pendulum, 5... fixed piece, 8... axial displacement absorption spring, 9... cantilever beam, 10... ...strain gauge, θ...angle of inclination.

Claims (1)

[Scope of Claims] 1. An inclinometer installed in a structure or the ground to measure deformation thereof, comprising a fixed part that tilts integrally with the object to be measured such as the structure or the ground, and this fixed part. a pendulum having one end attached to a beam part and a weight at the other end thereof and swinging in response to an inclination in a certain direction; and a pendulum extending from the fixed part to near the weight of the pendulum and substantially connected to the fixed part. An integral fixed piece;
a cantilever beam that is sufficiently shorter than the pendulum and has one end fixed to the fixed piece or the weight and the other end connected to the weight or the fixed piece via an axial displacement absorbing spring; 1. A strain gauge type inclinometer, comprising: a strain gauge attached to a strain gauge, and the strain gauge is configured to detect the inclination of the object to be measured using the strain gauge. 2. Claim 1, wherein the axial displacement absorbing spring is configured to absorb a tensile force generated in the cantilever beam based on the difference in axial length between the pendulum and the cantilever beam. Strain gauge type inclinometer as described. 3. The strain gauge type inclinometer according to claim 1, wherein the pendulum has a length and a cross-sectional shape that prevents the beam portion from buckling even when the pendulum is turned upside down. 4. The strain gauge type inclinometer according to claim 1, wherein the fixed piece extends to a position facing the weight so as to restrict the limit of the swing direction of the weight.