JPH0344643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for measuring the inner diameter of a pipe through which gas or liquid can freely flow.

Conventional Technology Conventionally, when water supply pipes, drain pipes, gas supply pipes, etc. are clogged with foreign objects and the flow becomes impaired, the pipes at the point where the blockage is likely to be removed are removed to search for the clogged area. It was under repair.

Problems to be Solved by the Invention As a result, searching for blocked areas takes time and involves a lot of wasted work, resulting in poor work efficiency.

By the way, as a method of measuring the inner diameter of a pipe, etc., a method using an ultrasonic device has been considered, but the equipment is complicated and expensive, and the frequency range for measuring the pipe diameter is narrow. Ta.

Furthermore, Japanese Patent Application Laid-Open No. 107110/1983 proposes that the outer surface of a tube be struck to find its frequency, and the amount of adhesion on the inner surface of the tube can be estimated from comparison with known tubes.

However, the above method requires a large amount of known measurement data, and is not a direct method as described above, but is only a method of estimating from a comparison of measurement data.

Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and uses a high-frequency exciter using an air jet to generate high-frequency waves in the range of not several KHz to several hundred KHz on the outer peripheral surface of a pipe through which gas or fluid flows. oscillate to measure the resonance frequency f(1) unique to the tube, and divide the speed of sound a propagating in the gas or liquid flowing inside the tube by this unique resonance frequency f(1), d=a/f(1). To provide a method for measuring the inner diameter of a pipe, etc., which is characterized by calculating the pipe diameter d from the relational expression (2).

Example Hereinafter, the present invention will be explained based on examples.

FIG. 1 is an example showing the measurement principle of the present invention. On a part of the outer peripheral surface of the tube 1 whose inner diameter etc. are to be measured, a high frequency exciter 2 using an air jet with a wide range of several KHz to several hundred KHz is installed so that it can be freely excited by an oscillation device 3, and this high frequency excitation is Shaker 2
A vibration detector 4 is provided on the outer peripheral surface of the tube 1 facing the
A resonance detection device 5 measures the unique resonance frequency caused by the high-frequency excitation. The resonance frequency detected by the vibration detector 4 is f(n), the speed of sound propagating in the gas or liquid flowing through the tube 1 is a,
If the inner diameter of the tube 1 is d, the relationship between the frequency f(n), the speed of sound a, and the inner diameter d of the tube 1 is f(n)=n×a/d. n is an integer of 1, 2, 3...

Therefore, the inner diameter d of the tube 1 can be found by using the resonance detection device 5 to find the unique resonance frequency f(1) as follows: d=a/f(1) (1).

Therefore, if the speed of sound a propagating in the fluid can be determined from the characteristic values of the fluid inside the pipe, the inner diameter d of the pipe 1 can be easily calculated, and even if there is a foreign object inside the pipe, Similarly, the effective inner diameter of tube 1 with foreign matter attached can be calculated, and the effective inner diameter of tube 1 in the initial state
By comparing the inner diameter of the pipe 1 with the inner diameter of the pipe 1, the clogging state of the pipe 1 can be measured from the outside of the pipe 1. In practice, the diameter of the tube used is approximately several mm to several hundred mm, and the sound velocity is several hundred m/sec in gas and approximately 1,000 m/sec in liquid, so the excitation frequency for measurement is teeth,
It is necessary to oscillate at several KHz to several hundred KHz, and it is optimal to use an air jet.

FIGS. 2 to 4 show an embodiment of the present invention. As shown in FIG. 2, the natural frequency measuring device 6 has an air jet high frequency exciter 2 removably attached to one end of a U-shaped holder 7, and is extendably screwed onto the other end with a screw mechanism 8. The vibration detector 4 is removably attached to the supporting part 9, and the high frequency exciter 2 and the vibration detector 4 are formed so as to be installed facing each other in the tube 1 of various diameters. High frequency exciter 2
is formed like a pipe nozzle as shown in Fig. 3, and in particular the front injection port 10 has a diameter of approximately
It has an orifice-like opening with a diameter of 1.0 to 1.2 mm and a length of approximately 1.8 to 2.0 mm, and an air hose 12 is connected to a hose connection port 11 at the rear to allow air to flow in. When the air pressure is set to 0.4 to 2.0 Kg/cm ² , it is possible to generate vibrations over a wide range of about 40 to 60 KHz and about 150 KHz, as shown in FIG. Further, as the vibration detector 4, a vibration sensor such as an electromagnetic type conversion, a piezoelectric type conversion, or a ceramic acceleration sensor is used, and it can be freely connected to a resonance detection device (not shown) to detect the resonance frequency. This is what we do. In addition, the high frequency excitation section and the vibration detection section on both sides of the natural frequency measuring device 6 are connected to the VV as shown in FIG.
The abutting surfaces are obtuse-angled V-shaped like a block, so that the outer circumferential surface corresponding to the diameter of the tube 1 can be accurately clamped at all times. Reference numeral 13 indicates a fixing screw for fixing the expandable support portion, and 14 indicates a lead wire for connecting the resonance detection device.

Function: For example, in a place where the inside of a pipe 1 such as a water pipe is thought to be clogged, the natural frequency measuring device 6 configured as described above is installed with a high frequency oscillator on the outer periphery of the pipe 1 as shown in Fig. 2. When the air hose 12 is connected to the hose connection port 11 of the high-frequency exciter 2 and air at a predetermined pressure is passed through the vibration detector, vibrations of several KHz to 150 KHz are generated as shown in Fig. 4. It oscillates, and the resonance frequency can be detected by the vibration detector 4 and resonance detection device. Therefore, if the sound velocity a is determined from the characteristic value of the fluid inside the pipe, the effective inner diameter d of the inside of the pipe 1 clogged with dirt can be calculated from equation (1), and the clogging status of the pipe 1 can be determined. be.

In this way, just by ejecting air as a high-frequency exciter, it is possible to easily and stably oscillate a wide range of frequencies from several KHz to over 100 KHz. The effective inner diameter can be measured easily and economically.

By measuring a plurality of tubes along the tube axis as described above, clogging along the tube axis can also be detected, and the situation can be accurately determined and dealt with accordingly.

The diameter of the air jet nozzle is preferably the one listed above, but it can be easily changed to another wide frequency range by simply changing the diameter. It is also possible.

Other Embodiments FIG. 5 shows another embodiment of the present invention, in which a high frequency exciter 2 and a vibration detector 4 of the air jet as described above are used.
are arranged concentrically to form the natural frequency measuring device 6.

In this example, the pipe diameter can be measured simply by touching the outer circumferential surface of the pipe without clamping the pipe with a holder.
Not only can large-diameter pipes be easily measured, but also gas pipes buried underground can be easily measured.

In the above case, the measurement of the state of clogging of the pipe adhering to the inner wall has been described, but the measurement of the state of corrosion of the pipe can also be carried out in the same way.

In addition, regarding calculation of the pipe diameter using equation (1), instead of performing calculations one by one, it is necessary to install a frequency analyzer, propagation velocity calculation data, data input device, data output device, etc., and use the specified microprocessor and interface. It can be outputted immediately via an intermediary, or it can be outputted as appropriate. In particular, it is preferable to use it for managing piping in a nuclear power plant or the like where safety is required, since maintenance can be automated.

In the above embodiments, circular pipes have been described, but the present invention can also be applied to rectangular duct pipes and channel pipes.

Effects of the Invention As described above, according to the present invention, it is possible to easily and stably generate high frequencies in a wide range of several KHz to several hundred KHz using an air jet, and the inner diameter of the pipe can be easily calculated from several KHz to several hundred KHz. It is possible to measure the resonant frequency f(1) unique to the tube in the range of several hundred KHz. Then, by dividing the sound velocity a in the gas or liquid flowing in the pipe to be measured by the above resonance frequency f(1), the required pipe diameter d=a/f(1) can be directly obtained. It can be easily calculated. Therefore,
It is possible to measure the state of clogging and corrosion of pipes from the outside, and to perform maintenance, inspection, etc. accurately and quickly.

[Brief explanation of drawings]

Fig. 1 is an explanatory sectional view showing the measurement principle of the present invention, and Figs. 2 to 4 are an embodiment of the same as the above, a partially omitted side sectional view of the natural frequency measuring device, and an enlarged view of the high frequency excitation part. A side sectional view and a frequency characteristic curve diagram of the high frequency exciter. FIG. 5 is a partially omitted side sectional view of another embodiment of the same. 1... tube, 2... high frequency exciter, 4... vibration detector,
6...Natural frequency measuring device.

Claims (1)

[Claims] 1. A high frequency exciter using an air jet is used to oscillate a high frequency in the range of several hundred KHz on the outer peripheral surface of a pipe through which gas or fluid flows, and the resonance frequency f(1) unique to the pipe is measured. Then, the speed of sound a propagating in the gas or liquid flowing in the pipe is divided by this unique resonance frequency f(1) = d=
A method for measuring the inner diameter of a pipe, etc., characterized in that the pipe diameter d is calculated from the relational expression of a/f(1).