JPS6251401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strain gauge type ring transducer type inclinometer that is installed on a retaining wall, a building, etc. or buried in the soil to measure its deformation.

Strain gauge (electrical resistance wire strain gauge)
has very good linearity in resistance change with respect to applied strain and good temperature characteristics, so it is widely used in various strain measurements and also in various transducers.

Various inclinometers using such strain gauges have been proposed and widely used in the past, and their principle is generally that of a cantilever type as shown in FIG.

That is, in FIG. 1, a strain gauge 4 is attached near the fixed part 1 of a cantilever 3 having one end fixed to the fixed part 1 and a weight w fixed to the lower end 2,
When the fixed part 1 is inclined and a certain inclination angle θ occurs, a bending moment is generated in the cantilever 3 by the component force Wθ of the weight W, and this bending moment causes cantilever 3
The strain gauge 4 is configured to detect changes in surface strain caused by the strain gauge 4. The advantage of this method is that it has a very simple structure and is easy to design.

However, in the above method, the strain output for a small inclination angle is small, and in order to increase this strain output, if the section modulus of the cantilever 3 is made smaller and the weight w is increased, the tensile force due to the weight w applied in the axial direction of the cantilever 3 is As the stress increases, a dilemma arises in that the surface strain of the cantilever 3, in other words, the strain output, must be designed to be small by that amount.This tends to lead to excessive design, which tends to lack robustness. It was hot.

Furthermore, as an improved version of the cantilever type inclinometer, a structure as shown in Japanese Patent Publication No. 54-4870 has been proposed. This conventional inclinometer is designed to be able to detect inclination angles smaller than the angle between the inclinometer and the vertical line with high sensitivity based on the inclinometer's buried position, regardless of its buried position. By combining a heating wire or electromagnet that operates in conjunction with the opening and closing of an external power source and the elastic force of a spring, a rotatable rotating body (gear) attached to a cantilever beam and a fixed part supported by the spring are combined. It has a structure in which a mechanical part for joining the parts is attached.

However, this latter type of inclinometer has the same problems as the former type of inclinometer, and also has the drawback that it requires electromagnets, gears, and other mechanical mechanisms as described above, making the structure complicated.

The present invention was made in view of these drawbacks, and its objectives are, firstly, to provide an inclinometer with good linearity, and secondly, to eliminate the dead load caused by the weight, which is directly related to strain detection. By supporting it with an unrelated rigid arm, it is possible to eliminate the influence of tensile stress caused by a weight like in the conventional cantilever type, and to provide an inclinometer that is difficult to break. A fourth object of the present invention is to provide an inclinometer that can obtain strain output.A fourth object is to provide an inclinometer that does not have a mechanical mechanism and can obtain stable strain output over a long period of time.

In order to achieve such an object, the present invention includes a hanging arm whose upper end is swingably attached to a fixed part, a weight fixed to the lower part of the hanging arm,
Two ring-shaped transducers each having a strain gauge attached thereto are interposed between the side fixing parts disposed on both sides of the hanging arm in the swing angle direction and the hanging arm. be.

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

FIG. 2 is a schematic configuration diagram schematically showing the configuration of an embodiment of the present invention.

In the same figure, a pendulum 14 is swingably attached to the upper fixed part 12 of the inclinometer main body by a hinge 11 provided at the upper end, and has a weight w fixed to the lower part 13.
Two ring-shaped transducers 16 and 17 are attached to both sides of the hanging arm 15 in the swing angle direction, and when an inclination angle occurs in the upper fixed part 12, W
A tensile force or a compressive force is applied to the ring-shaped transducers 16, 17 by the component force of the weight w having a weight of , and a strain is generated on the surface of the ring-shaped transducers 16, 17. The strain on this surface is measured by strain gauges 18, 19, 22, 2 bonded to the inner and outer surfaces of ring-shaped transducers 16 and 17.
3 and 20, 21, 24, and 25, and an electrical signal corresponding to the tilt angle can be obtained to measure the tilt angle. In addition, strain gauge 18-2
5 is about 90 degrees clockwise from the point where the ring-shaped transducers 16 and 17 are attached to the depending arm 15.
They are attached to the inner and outer surfaces at angular intervals of approximately 90° in the counterclockwise direction by adhesive or other means. The ring-shaped transducers 16, 17 are then fixed at points 26, 27 to the lateral fixing parts 12', 12'' of the inclinometer body, respectively.

FIGS. 3A and 3B are two of the embodiments shown in FIG.
These are schematic configuration diagrams showing two modified examples. , which may be configured as shown in FIGS. 3A and 3B. In addition, in FIGS. 3A and 3B, parts corresponding to those in FIG. 2 are given the same reference numerals.

FIG. 3A shows the ring-shaped transducers 16 and 17 fixed at the same height position as the weight w, and FIG.
1 shows a state in which the ring-shaped transducers 16 and 17 are fixed to an arm portion 15' which extends the hanging arm 15 of the pendulum 14 further downward than the weight w. These third
Both embodiments shown in FIGS. A and B are based on the same principle as the embodiment shown in FIG. , can be measured as an electrical signal.

FIG. 4 is an explanatory diagram for determining the optimal design values of the strain gauge ring transducer type inclinometer according to the present invention, where the weight of the weight w is W, the pivot point of the hanging arm 15 to the upper fixed part 12 is (or attachment point), that is, the partial length from the hinge 11 to the fixing point of the weight w is L, from the hinge 11 which is the pivot point to the upper fixing part 12 of the hanging arm 15 to the ring-shaped transducer 16, 17
Let the length of the part up to the fixed point be l, and the inclination angle be θ, then the surface strain ε of the ring-shaped transducers 16 and 17 at the position where the strain gauges 18 to 25 are bonded is as follows: When |θ|≪1 , ε=±C ₁ LWl/l ² +C ₂ LW·θ (1), and the surface strain ε is proportional to the inclination angle θ. Note that C ₁ and C ₂ are constants determined by the material and shape of the ring-shaped transducers 16 and 17. Now, if we set C ₁ LWl/l ² +C ₂ LW=Φ...(2) and graph the relationship between l and Φ with Φ as a function of l, we will obtain a curve as shown in Figure 5,
It can be seen that there exists a value l ₀ of l that maximizes Φ.

So, when we find l ₀ , we get l ₀ =√ ₂ ...(3). Therefore, the ring-shaped transducers 16, 17 are
The length l from the upper end hinge 11 of the hanging arm 15 of the pendulum 14 (including the arm portion 15' in which the hanging arm 15 in the embodiment shown in FIG. 3B is extended below the weight W) is l ₀ Point 27 is shown in (3) above.
At this point, the ring-shaped transducer 1
6, 17 are fixed to the hanging arm 15, the magnitude of the surface strain ±ε of the ring-shaped transducers 16, 17 is maximized.

FIG. 6 shows ring-shaped transducers 16, 17 in each embodiment shown in FIG. 2, FIG. 3 A, B, and FIG.
FIG. 2 is a circuit diagram showing an example of how to assemble a Wheatstone bridge for taking out the outputs of strain gauges 18 to 25 attached to the wafer. In Figure 6, force terminal 2
When voltage (or current) is applied between 8 and 29,
A voltage output proportional to the tilt angle θ is obtained between the output terminals 30 and 31. In the illustrated example, the strain gauges 18 and 21, 19 and 20, etc. are connected in series to form a bridge, but these may be connected in parallel, or the strain gauges 18 to 21 or The bridge may be composed of only 18, 20, 23, and 25.

FIG. 7 is a perspective view showing the structure of another embodiment of the invention shown in FIG. 2, which is a further embodiment of the invention. In FIG. 7, parts corresponding to those in FIG. 2 are designated by the same reference numerals.

In the figure, 32 is the inclinometer main body as a casing that supports the inclinometer, and includes a rectangular parallelepiped-shaped pedestal 33 at the bottom, and lateral fixing parts 34 and 35 erected on the left and right sides of the pedestal 33. , these side fixing parts 34,
35, and a hinge 37 (corresponding to the hinge 11 in the embodiment shown in FIG. 2). A hinge 37 provided on the upper fixed part 36 of this inclinometer main body 32 has a hanging arm 1.
The upper end of the hanging arm 15 is swingably attached, and a weight w is fixed to the lower part (lower end in this case) of the hanging arm 15, and the left and right sides of the hanging arm 15 and the side fixing portion Ring-shaped transducers 16 and 17 are interposed between the transducers 34 and 35, respectively.
The ring-shaped transducers 16 and 17 are respectively fixed at the same height position of the hanging arm 15 with setscrews 38 and 39, and are further fixed at the same height with an angular interval of 180° from this fixing point. Attach the set screws 40, 4 to the side fixing parts 34, 35 at the
1, 40', and 41'.

In the embodiment shown in FIG. 7 configured in this way, when the pedestal 33 is tilted by a certain angle of inclination, the inclinometer main body 32, that is, the side fixing parts 34, 3
5. The upper fixed part 36 is also tilted, and the pendulum 14 (weight w
The hanging arm 15) swings, and the component force due to the weight w is transmitted through the hanging arm 15 to the ring-shaped transducer 16,1.
7, and its surface strain changes. The strain gauges 18 to 25 (only strain gauges 20 and 24 are shown in FIG. 7) detect this surface strain and send out a voltage output proportional to the tilt angle. can be measured.

FIG. 8 is a sectional view showing the configuration of still another embodiment of the present invention, and parts corresponding to those in FIG. 7 are given the same reference numerals.

This embodiment is a more specific embodiment of the embodiment shown in FIG. 7, and is the most preferred in practice.

In this embodiment, the inclinometer main body 32 is housed in a case 42, and the inside of the inclinometer main body 32 is filled with a damping material 43 such as silicone oil to reduce noise components caused by high frequency vibrations and the like. Further, the pedestal 44 is made into a round shape, and an O-ring 45 is interposed between the pedestal 44 and the case 42 to prevent the damping material 43 from flowing out. Furthermore, in the center of the pedestal 44, there is a conical protrusion 4 at the tip.
A stopper 48 having a handle 47 at the other end is attached with an O-ring 49 interposed therebetween. This stopper 48 prevents overload during use (when measuring the inclination angle), and also prevents the handle 4 from being overloaded when the inclinometer is moved until it is installed at the location to be measured.
7 to bring the conical protrusion 46 into close contact with the conical recess 50 formed at the bottom of the weight w, thereby preventing the pendulum 14 from swinging due to external vibrations.

It should be noted that the present invention is not limited to the embodiments described above, and it goes without saying that various changes, combinations, and substitutions can be made without departing from the spirit of the invention.

For example, the number of strain gauges, their arrangement positions, connection circuits, etc. can be changed as appropriate, and the means for attaching the strain gauges is not limited to adhesion, but may also be fusion bonding, vapor deposition, sealing, etc.

Furthermore, the means for attaching the upper end of the hanging arm to the upper fixed part may be any type of means, such as a combination of a shaft and a bearing, or a method suspended from a ribbon as shown in Figures 7 and 8. In short, the hanging arm may be attached so as to be swingable.

As detailed above, according to the present invention, unlike conventional strain gauge type inclinometers in which a strain gauge is attached to a cantilever whose upper end is fixed and a weight is attached to the lower end, a weight is attached to the lower end. Strain gauges were not attached to the swingable hanging arm itself, which was fixed, but were inserted between the hanging arm and the side fixing parts arranged on both sides of the hanging arm in the swing angle direction. Since it is made by attaching a strain gauge to a ring-shaped transducer, it is not affected by the tensile stress caused by a weight like the conventional cantilever method, and it is possible to obtain a large strain output even for a small tilt angle. At the same time, it is possible to obtain a strain output according to the inclination angle with good linearity.

Furthermore, unlike the conventional cantilever system, the one of the present invention does not cause strain on the hanging arm itself to which the weight is fixed, so a rigid material can be used for the hanging arm. It can be used as an inclinometer that is hard to break.

Furthermore, according to the present invention, the attachment (fixation) position of the ring-shaped transducer to the hanging arm is adjusted to the above (1) to (3).
By considering the formula and setting it, you can create an inclinometer with any performance and characteristics, from one suitable for measuring minute inclination angles to one suitable for measuring relatively large inclination angles of about 0.1 to 0.2 radians. Therefore, the degree of freedom in design increases and it becomes possible to provide an inclinometer that is optimal for on-site measurement.

Furthermore, as is clear from the above, the present invention provides an inexpensive inclinometer that has a simple configuration and does not have a mechanical mechanism, and is therefore capable of obtaining stable strain output over a long period of time. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional strain gauge type inclinometer, FIG. 2 is a schematic configuration diagram schematically showing the configuration of an embodiment of the present invention, and FIGS. 3A and B are shown in FIG. 4 is an explanatory diagram for determining optimal conditions for carrying out the present invention, and FIG. 5 is a diagram obtained by predetermined calculations based on FIG. 4. Figure 6 is a circuit diagram showing an example of a Wheatstone bridge constructed by combining strain gauges, and Figure 7 is a diagram showing a further embodiment of the present invention shown in Figure 2. FIG. 8 is a perspective view showing the structure of the embodiment shown in FIG. 11, 37... Hinge, 12, 36... Upper fixing part, 12', 12'', 34, 35... Side fixing part, 13... Lower part of hanging arm, w... Weight, 1
4... Pendulum, 15... Drooping arm, 16, 17...
...Ring transducer, 18-25...Strain gauge, 32...Inclinometer body, 33...Pedestal.

Claims (1)

[Claims] 1. An inclinometer installed on a retaining wall, a building, etc. or buried in the soil to measure deformation thereof, comprising a hanging arm whose upper end is swingably attached to a fixed part;
A weight fixed to the lower part of the hanging arm, and a strain gauge attached to the hanging arm are interposed between a lateral fixing part provided on both sides of the hanging arm in the swing angle direction and the hanging arm. A strain gauge type ring transducer type inclinometer, comprising: two ring transducers. 2. The strain according to claim 1, wherein the two ring-shaped transducers are respectively fixed to the side fixing part and the hanging arm at respective contact parts between the side fixing part and the hanging arm. Gauge type ring transducer type inclinometer. 3. The ring-shaped transducer is configured such that the weight of the weight is W, the length of the portion from the pivot point to the upper fixation part of the hanging arm to the fixation point of the weight is L, and the material of the ring-shaped transducer is , C is a constant determined by the shape, and l is the length of the portion from the pivot point of the hanging arm to the upper fixed part to the fixed point of the ring-shaped transducer.
The strain gauge ring transducer type inclinometer according to claim 1 or 2, wherein the hanging arm is fixed at a position where l=√.