JPH043809B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse height measurement method and a detector used to carry out the method.

Wave height measurement is a method of measuring the wave height of actual large waves generated at sea and small waves generated by experimental equipment using electrical means.

Conventionally, there are two types of detectors used for wave height measurement, one of which is to immerse the tip of the detector in liquid and detect the capacitance of the part of the detector submerged in liquid.
Others detect the electrical resistance of liquids.

The former capacitance detection type has a detection line 84 covered with insulation in the detector 80, as shown in FIG.
The detection wire 84 is immersed in water to form a capacitor between the metal conductor at the core of the detection wire 84 and the water, and changes in capacitance due to changes in water depth H are detected.

The detector 80 and the measuring device main body 8 are connected by a transmission line 81 and a detection signal line 82, and a high frequency signal from a sine wave oscillating section 83 of the measuring device main body 8 is transmitted to the detector 80 via the transmission line 81. A capacitance change due to changes in water depth is converted into a voltage change proportional to the capacitance in a capacitance-voltage converter 85 in the detector 80, and the converted voltage signal is sent to the measuring device via a detection signal circuit 82. The signal is sent to a DC amplifier 86 built into the main body 8 and output to a meter output section 87 and/or a recorder 88.

As shown in FIG. 7, the latter liquid electrical resistance detection method involves submerging a pair of measuring electrodes 9, 90 arranged vertically in parallel in the liquid to an arbitrary depth, and then touching the tips of the measuring electrodes 9, 90 in the liquid. Compensation electrodes 93, 93 nearby
The measurement electrodes 9, 90 and the compensation electrode 9
3 and 93 are connected to the bridge 92, a voltage is further applied to maintain the balance in still water, and the wave height is measured by detecting the resistance change of the measurement electrodes 9 and 90 based on the water level change after the start of measurement. It is something to do. The electrical resistance of water changes depending on the water temperature and water quality, but bridge correction is performed by the compensation electrodes 93, 93, and the water temperature and water quality are changed.
This measurement method prevents measurement errors from occurring even if water quality changes.

The above-mentioned conventional devices have various problems as follows. First, the capacitance detection method has a slow signal response and cannot measure waves with a period of 3 Hz or more, and if air bubbles are mixed in the liquid, the capacitance changes and accurate data cannot be collected.

In the electrical resistance detection method, when a wave passes between two measurement electrodes, the water depth of each measurement electrode differs depending on the angle of the wave. As a result, the resistance value of the bridge becomes the average value of both electrodes, so true value data cannot be obtained.If air bubbles are mixed in the liquid, the resistance value changes and accurate data cannot be collected.

The present invention aims to clarify a measurement method that can accurately measure wave heights that fluctuate with wave motion by faithfully following complex waveforms that include the fundamental wave and high frequency of waves, and a detector used to implement the method. purpose.

The principle of wave height measurement in the present invention is that when the electrode rod on the oscillation side is made of an electrically resistive material and a constant AC voltage is applied between both ends of the electrode rod, a voltage will be generated in the liquid or above the liquid surface of the electrode rod. The length of the oscillating electrode changes proportionally or inversely to the wave height of the liquid, and the potential difference between the electrode rod in the liquid or above the liquid surface corresponds to the liquid surface height, so the liquid surface potential near the oscillating electrode rod is measured. By doing this, you can know the liquid level height.

The detector of the present invention has an oscillation line made of an electrical resistance material and a detection line made of a conductive material arranged in parallel in the detector, and the oscillation line is connected to an oscillating part of an alternating current signal. is characterized in that a signal output section is connected.

The method of the present invention involves submerging the oscillation line and detection line of the detector in a liquid at any position from the tip to the middle part,
A sinusoidal voltage is applied between the top and tip of the oscillation line made of resistive material. The detection line is characterized by detecting the potential of the liquid surface, displaying the submerged position of the oscillation line, and displaying the wave height by calibrating it.

In particular, the method of the present invention faithfully follows the fluctuating wave height of the wave and outputs the wave height at each moment by making the AC signal applied to the oscillation line a high-frequency signal with a frequency sufficiently higher than the frequency of the wave. It has the advantage of being visible.

A specific example of the present invention will be explained in the case where it is applied to wave height measurement on the water surface. However, the device and method of the present invention can be applied not only to water but also to conductive liquids such as alcohol, acid, and alkaline liquid. can also be implemented.

It goes without saying that it can be used not only for measuring wave height, but also as a liquid level gauge for tanks or tanks.

As shown in Fig. 1, the measuring device has a detector 4 connected to the device body 1 through a signal line 3, and the device body 1 electrically measures the liquid level detected by the detector 4. The value is output to a recorder 6 such as a printer or recorder and a display 61 such as an oscillograph.

On the operation surface of the device main body 1, there is a voltmeter 11 that displays the detected voltage from above, a changeover switch 12 that selects the display width in volt range according to the scale of the wave,
Adjustment volume 1 to set the reference liquid level before measurement
3 and a connector 7 for connection to the signal line 3 are arranged vertically to constitute one channel, and the illustrated embodiment has three channels.

The device main body 1 has a signal output section 2 and a signal conversion section 5. The signal output section 2 oscillates a sine wave signal by a two-phase oscillation circuit 20, amplifies it with an amplifier 21, and sends it to the detector 4. send to

An oscillation line 40 and a detection line 41 are connected in parallel to the detector 4, the oscillation line 40 is connected to the signal output section 2 of the device body 1 via the transmission line 32, and the detection line 41 is connected to the detection signal The device main body 1 via the line 35
It is connected to the signal conversion section 5 of.

The signal converter 5 receives the signal from the detector 4, first amplifies it with an AC amplifier 50, then extracts the set gain with a high-pass filter 51, and then passes it to a full-wave rectifier 52.
After converting the signal into DC, it is amplified by a DC amplifier 53, the set gain is extracted by a low-pass filter 55, and sent to a DC amplifier 57, and finally to a recorder 6,
The signal is output and displayed on the display 60.

The signal output section 2 of the device main body 1 outputs the oscillation line 40 of the detector 4 regardless of the internal resistance and route of the signal line 3.
An example of this is shown in FIG. 3.

The signal output section 2 includes a known two-phase oscillation circuit 20, sets the oscillation frequency to 2.3 KHz and the voltage to 250 mV, and inputs this to the amplifier 21. The basic output voltage of the amplifier 21 is controlled by the operational amplifier 22, and the voltage at the output terminal 70 is applied to the oscillation terminal 42 of the oscillation line 40 via the transmission line 32, and at the same time a feedback signal branched from the oscillation terminal 42 is applied. It is connected to the input side of the operational amplifier 22 via a line 31. Therefore, the operational amplifier 22 controls the output of the voltage applied to the oscillation line 40 of the detector 4 so that the voltage returned to the operational amplifier 22 via the feedback line 31 becomes the set value, and the voltage applied to the oscillation terminal 4
A constant voltage is applied to 2.

In the embodiment, the signal line 3 has a length of 30 m, is formed of a 7-pole coaxial cable, and has connectors at both ends. Transmission line 3 for transmitting sine wave signals
2 and the detection signal line 35 are connected to the ground wire 33,
It is a twisted pair wire with 36. Furthermore, shield earths 34 and 37 are provided for each twisted pair of wires. Also, the shield earth 34 for the transmission line 32 includes the feedback line 31 described above.

As shown in FIG. 4, the detector 4 has one end of the signal line 3 fixed to the upper surface of a case 45 made of an insulating material, and a support made of stainless steel tube whose lower end is bent into an L shape on the lower surface of the case 45. A rod 44 is provided protruding.

Between the support rod 44 and the support plate in the case 45,
An oscillation line 40 and a detection line 41 are stretched in parallel with each other via springs 48, 48, respectively.

The length and interval between the oscillation line 40 and the detection line 41 vary depending on the wave height of the wave to be measured, but if the measured wave height is within 50 cm, the length of the line is 50 cm. The gap may be arbitrary, but a spacing of about 1.5 cm is practical.

The oscillation wire 40 is a resistance wire made of an electrically resistive material such as nichrome wire, and is set to a value sufficiently smaller than the electrical resistance of the liquid to be measured.
It has a load of about 0.2Ω/cm. The upper measurement end P ₁ is connected to the transmission line 32 in the signal line 3, and the lower measurement end P ₂ is electrically connected to the ground wire 46 inserted into the support rod 44 and maintained at OV. The ground wire 46 passes through the support rod 44 and draws its upper end into the case 45, and connects the ground wire 3 in the signal line 3.
3, 36 and shield earths 34, 37.

Further, the surface of the support rod 44 and the area below the measurement lower end _P2 of the oscillation line 40 are coated and insulated.

The detection wire 41 is a stainless steel wire whose lower end is fixed to the support rod 44 via an insulating material, and is electrically insulated from the support rod 44 and the oscillation wire 40 .
When the detector 4 is submerged in a conductive liquid, the detection line 41 is electrically connected to the oscillation line 40 only through the conductive fluid. The voltage of the oscillation line 40 drops uniformly at each point between the upper end P ₁ connected to the transmission line 32 and applied with a constant voltage and the lower end P ₂ connected to the arm line.

Therefore, at the midpoint P ₀ (not shown) where the liquid level intersects the oscillation line 40, the voltage of _{0 2} is proportional to the line length for a constant voltage between _{1 2} . The voltage at point P ₀ is applied to the detection line 41 via the liquid surface. Further, the upper end of the detection line 41 is connected to the detection signal line 35 in the signal line 3.

The signal processing from the detection line 41 is performed by the second
Processed by the signal converter 5 shown in the figure, the recorder 6,
The respective wave heights are displayed on the display 60.

When performing wave height measurement, the reference liquid level is set using the adjustment volume 13, and the output range for the recorder 6 and display 60 is set to either 200 mV/cm or 100 mV/cm using the changeover switch 12. After setting, start measurement.

FIG. 5 shows another embodiment of the present invention, in which a plurality of detectors 4, 4 are arranged in the direction of wave propagation and placed in the tank, and it is possible to measure the wave height and the instantaneous waveform. be. Signal transmission and reception between the detector 4 and the device main body 1 is distributed by multiplexers 23 and 59 on the output side and the input side, and each detector 4 is connected to the signal output section 2 and the signal conversion section 5 one after another. A graphic processor 62 is connected to the output terminal 58 of the signal converter 5 to display the shape of the surface wave.

The present invention is based on the novel idea of receiving and detecting the high frequency signal applied to the detector 4 on the surface of the wave when measuring the wave height as described above. Detection line 40
By setting the high-frequency signal applied to the wave sufficiently higher than the wave period, it is possible to read values even smaller than the high-order harmonics generated on the liquid surface, and the measurement accuracy is compared to conventional capacitance detection types. The accuracy is extremely high. For example, when measuring the wave height on the coast using a conventional capacitive detector, the wave period is 0 to 3 Hz, so it is expected that a graph like the one shown in Figure 9 will be drawn. By adding a signal with an oscillation period of 2.3 KHz, it is possible to faithfully follow fluctuations in wave height as shown in Figure 8.

In addition, in conventional devices, errors in measurement values occur due to changes in the electrical resistance of water due to changes in water quality and water temperature, whereas in the present invention, the height of the liquid surface touching the oscillation line is Since the length above the liquid level is determined and the electrical resistance is changed just like a variable resistor, the current flowing through the detection line 41 is detected and the height of the wave is expressed, so almost no error occurs.

Furthermore, since the present invention uses alternating current on the oscillation side, the lifetime of the detector 4 is prevented from being shortened due to ion generation, unlike when direct current is used.

Conventionally, it was impossible to measure when the water flow rate was high and air bubbles were mixed in during measurement, but with the present invention, the wave height can be directly measured from the wave surface regardless of the state of the liquid in the liquid. It has excellent effects such as.

It should be noted that the present invention is not limited to the above-mentioned configuration, and it goes without saying that various modifications can be made within the technical scope of the claims.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2 is a block diagram of the main body of the device, Fig. 3 is a schematic diagram showing wiring and connections between the main body of the device and the detector, and Fig. 4 is a cross section of the detector. 5 is a block diagram showing another embodiment of the detector, FIGS. 6 and 7 are block diagrams of a conventional device, and FIG. 8 is a graph showing temporal changes in wave height according to the method of the present invention. FIG. 9 is a graph of the same according to the conventional method. DESCRIPTION OF SYMBOLS 1...Device body, 2...Signal output section, 3...Signal line, 4...Detector, 40...Oscillation line, 41...
...Detection line, 5...Signal converter, 6...Recorder.

Claims (1)

[Scope of Claims] 1. In a method of measuring wave height by arranging two electrode wires and submerging their tips into the liquid to be measured, one of the electrode wires is an oscillating wire made of an electrically resistive material. The other electrode wire is a detection wire made of a highly conductive material, and the tips of both electrode wires are submerged in the conductive liquid to be measured, and the lower part of the oscillation wire submerged in the liquid is grounded. , apply an AC voltage to the upper part of the oscillation line above the liquid level, and apply the voltage of the oscillation line at the position where the liquid level touches the oscillation line to the detection line through the liquid surface to detect the voltage corresponding to the liquid level height. A wave height measuring method characterized by displaying the liquid level height. 2. The method according to claim 1, wherein the alternating current voltage applied to the oscillation line is a sine wave voltage with a sufficiently high frequency compared to the period of the wave. 3 A plurality of pairs of electrode wires consisting of an oscillation line and a detection line are arranged along the direction of wave propagation, and each pair of oscillation line and detection line is used to apply an alternating voltage, and from the oscillation line through the liquid surface. 2. The method according to claim 1, wherein the voltage detection is sequentially switched by a multiplexer. 4. In a detector that measures wave height by lining up two electrode wires and submerging the tips of each into the liquid to be measured,
One electrode wire is made of electrically resistive material and the other electrode wire is made of electrically conductive material, with the upper part of the electrode wire made of electrically resistive material being connected to an AC voltage source and the lower part being made of electrically resistive material. is connected to a ground wire, the upper part of the other electrode wire made of a conductive material is connected to a signal exchange part, and the lower part is connected to an insulating material.