JPH11281464A - Ultrasonic level sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To predict the water level in a tank installed in a tunnel at a prescribed accuracy or more and prevent error detection caused by a substance stuck to a cylinder attached in the adjacent to an ultrasonic transmitting/ receiving part. SOLUTION: A judgment timing prediction means 8 predicts an abnormality judgment timing in a timing prediction preparation mode based on distance data 12 from a distance operation means and writes the position of the level measured according to each timing in a judgment liquid surface position memory means 10. An abnormality judgment means 9 compares the distance data 12 from a distance operation means 6 with a judgment liquid level data 15 from the judgment liquid surface positions storage means 10 to judge it abnormal or not. If it is judged abnormal, the distance data 12 is registered in an abnormal data memory means 11 and the judgment liquid surface position data 15 is outputted as an outputted signal 19 substitute for the present distance data 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic level sensor used mainly in a liquid level control system such as a drainage treatment system in a canal.

[0002]

2. Description of the Related Art Generally, a kind of tunnel called a tunnel is provided in the ground under a large road such as a main road, and various cables such as a communication cable and a power cable are laid in the tunnel. ing. A drainage ditch is also provided in the cave to collect rainwater and the like that has nowhere to go on the ground surface. Rainwater flowing through this drain is temporarily stored in a tank called a drain pit,
When the tank is filled to near the capacity of the tank, the water is drained out of the tank by a drain pump and then sent to another location.

[0003] If the amount of rainwater flowing into the above-mentioned tank exceeds an allowable amount and a situation occurs in which rainwater overflows from the tank, there is a possibility that the cable will be flooded. Therefore, in order to prevent such a situation from occurring, an ultrasonic level sensor is installed near the water surface of the tank to constantly monitor the water level, and when the water level reaches a preset upper limit, drainage by the drain pump is performed. Is about to start.

[0004] By the way, a cylinder having a length longer than the distance between the upper limit value and the lower limit value is usually attached near the ultrasonic transmission / reception section of the ultrasonic level sensor. This is because various pipes, cables, and other members are provided in the tank, and in order to prevent these members from being erroneously detected as the water surface, the above-described cylinder is attached to the sensor. This is because it is necessary to limit the directivity of the ultrasonic wave within a certain range.

[0005]

However, after a certain period of time, foreign matter such as dust and water-containing dust gradually begins to adhere to the inside and near the end of the cylindrical body. A kimono may be erroneously detected as a water surface. Here, the worker regularly checks whether or not the ultrasonic level sensor is operating normally. However, there is a case where the deposit adheres to the cylindrical body before the worker checks. . Also, if the ultrasonic level sensor indicates abnormal operation or the dirt near the cylinder is severe, the worker may notice the deposit on the cylinder and perform the cleaning work of the cylinder. At present, the attached matter on the cylindrical body is often overlooked.

[0006] As one of the measures for preventing such erroneous detection due to the adhered matter on the cylindrical body, the water level in the tank is predicted, and when the difference between the predicted value and the detected value is larger than a certain value, It has been conventionally considered to add a function of invalidating the detected value. However, since the inflow of rainwater into the tanks in the tunnel is irregular and the shapes of the tanks are various, it is very difficult to predict the water level in the tanks. It was difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and makes it possible to predict the water level in a tank installed in a sinus with a certain degree of accuracy, and to thereby provide a cylindrical body attached near an ultrasonic transmitting / receiving unit. It is an object of the present invention to provide an ultrasonic level sensor capable of preventing erroneous detection due to an attached matter.

[0008]

As a means for solving the above-mentioned problems, the invention according to the first aspect of the present invention is to detect a liquid surface position by an ultrasonic level sensor provided with a cylinder for improving directivity. Based on this detection, when the liquid level of the liquid flowing irregularly into the container reaches a predetermined upper limit, the liquid starts discharging out of the container and reaches the lower limit. Sometimes, in a liquid level control system that performs control to stop this discharge, a plurality of determination liquid level positions at which abnormality determination is to be performed within an area between the upper limit value and the lower limit value are set and stored in advance. Surface position storage means, determination timing prediction means for predicting each determination timing when the liquid surface position of the liquid surface to be detected reaches each determination liquid surface position stored in the determination liquid surface position storage means, The discrimination timing The detected liquid level position detected at each determination timing predicted by the means is compared with each of the determined liquid level positions stored in the determined liquid level position storage means. Abnormality determination means for determining that the data of the detected liquid surface position is abnormal when it occurs, and when the abnormality determination means determines that there is an abnormality, the determination liquid surface position corresponding to the determination timing Is output as a detection liquid level position.

In the invention according to claim 2 or claim 1, the abnormality determining means registers the data determined as abnormal in the abnormal data storage means as abnormal data, and thereafter registers the detected liquid level. When the data is no longer determined to be abnormal, the registration of the abnormal data is deleted.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a timing prediction preparation mode is set. In the case where one cycle is performed until the time when the discharge is stopped, the liquid level moving speed and the liquid level moving time of the liquid level position in the first cycle between the upper limit value and the lower limit value are measured, and the measurement results are obtained. , The liquid surface movement time Tx in the second cycle is predicted, and the liquid surface movement time Tx, the scan time Ts, and the number M of memory addresses of the liquid surface position storage means are used to determine each of the determined liquid surface positions. Are calculated, and the respective liquid level positions in the second cycle at the calculated respective determination timings are measured, and the measured values are referred to as the determined liquid level. Written to each storage area corresponding to each memory address of the determined liquid level position storage unit as, and wherein the.

According to a fourth aspect of the present invention, in the third aspect, the abnormality determining means sets the first set value when a difference between the detected liquid level position and the determined liquid level position is equal to or greater than a predetermined value. The abnormality determination is not performed when the error occurs at each of the memory addresses consecutive by the number N1.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the abnormality determining means determines that the difference between the detected liquid level position and the determined liquid level position is equal to or greater than a predetermined value. The second set number N which is smaller than the set number N1
When two consecutive memory addresses occur, the data of the detected liquid level position is determined to be abnormal.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the liquid level control system is an in-cave drainage treatment system for controlling a water level of a drainage pit in a cave. It is characterized by the following.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the present embodiment. In this figure, a tank 1 is installed in a cave, and rainwater flows in from an inlet 1a and is stored, and the stored rainwater is drained from a drain pump 2 through a drain port 1b. I have. A small-diameter cylinder 4 having a length equal to or greater than the distance between the upper limit value and the lower limit value is attached near the transmission / reception unit 3 of the ultrasonic level sensor, and the transmission / reception between the transmission / reception unit 3 and the water surface in the tank 1 is performed. The directivity of the ultrasonic waves to be transmitted is limited.

The ultrasonic signal from the water surface received by the transmitting / receiving section 3 is output to the distance calculating means 6 via the receiving circuit 5,
Here, the distance from the transmitting / receiving unit 3 to the water surface, that is, the water level is calculated, and the value is displayed on the display 7. In FIG. 1, illustration of other circuits such as a transmission circuit and an amplification circuit is omitted for simplification of the drawing. The detection signal of the ultrasonic level sensor is sent to the drive control circuit of the drainage pump 2 and drainage starts when the water level rises to the upper limit of the tank 1 and stops when the water level drops to the lower limit. It is supposed to be.

The ultrasonic level sensor according to the present embodiment
The above-described conventional configuration is provided with a judgment timing predicting means 8, an abnormality judgment means 9, a judgment liquid level position storage means 10, and an abnormality data storage means 11. In this embodiment, for example, an EEPROM is used as the discrimination liquid level position storage means 10, and a RAM is used as the abnormal data storage means 11, for example.

The distance data 12 calculated by the distance calculation means 6 is output to the judgment timing prediction means 8 and the abnormality judgment means 9 in addition to the display 7. Based on the distance data 12, the determination timing prediction means 8 predicts the timing of the abnormality determination in the timing prediction preparation mode, and writes the position of the water surface measured according to each timing as the determination liquid surface position. The writing signal 13 is output to the discrimination liquid level position storage means 10. Further, the determination timing prediction means 8 outputs the timing signal 14 to the abnormality determination means 9.

The abnormality judging means 9 compares the distance data 12 from the distance calculating means 6 with the discriminating liquid surface position data 15 from the discriminating liquid surface position storing means 10 every time the timing signal 14 is inputted. Is determined. When the abnormality determining means 9 determines that the distance is abnormal, the abnormality data storing means 11 stores the distance data 12.
And outputs an abnormality determination signal 17 to the distance calculation means 6. Upon receiving the abnormality determination signal 17, the distance calculation means 6 outputs the determination liquid level position data 15 from the determination liquid level position storage means 10 as an output signal 19 instead of the current distance data 12.
In the next and subsequent cycles, the distance calculation means 6 stores the abnormal distance data 12 in the abnormal data storage means 11.
Can be read as the abnormal data 18 from the distance data.
Instead of 2, the discrimination liquid level position data 15 is output as an output signal 19.

Next, the operation of the present embodiment configured as described above will be described. FIG. 2 is a flowchart showing a main operation of the ultrasonic level sensor. First, initial settings are performed (step 1), and a firing program is executed (step 2). Then, the ultrasonic waves reflected on the water surface in the tank 1 are transmitted to the distance calculating means 6 through the transmitting / receiving section 3 and the receiving circuit 5, and the distance is calculated (step 3).

The distance data calculated by the distance calculation means 6 is sent to the discrimination timing prediction means 8, and the discrimination timing prediction means 8 prepares for discrimination timing prediction (step 4). FIG. 3 is a flowchart showing the contents of the timing prediction.

Now, it is assumed that the water level in the tank 1 is at the level of the lower limit, and that the state is immediately after the drainage is stopped.
If the water surface rises from the lower limit level to the upper limit level and then falls back to the lower limit level in one cycle, the rising water surface near the upper limit reaches the upper limit, and then reaches the upper limit. Let's consider about half a cycle from when the temperature drops to the lower limit.

First, in the first cycle, the discriminating timing predicting means 8 calculates a water increasing speed V1 near the upper limit value based on the distance signal from the distance calculating means 6 (step 21). The drainage speed Vh in the vicinity is calculated (step 22). Thereafter, when the water level reaches the upper limit, drainage by the drainage pump 2 is started. Therefore, the water surface falls from the upper limit value to the lower limit value, but the discrimination timing prediction means 8 measures the time during which the water surface moves the distance (span S) between the upper limit value and the lower limit value, that is, the drainage time T ( Along with step 23), the average drainage speed Vha between the spans S is calculated using the equation Vha = S / T (step 24). Then, the discrimination timing predicting means 8 calculates the average water supply speed Vza from the obtained water supply speed V1, the drainage speed Vh, and the average drainage speed Vha as Vza = (V
ha / Vh) · V1 (Step 2)
5). Here, if Vha / Vh = α, then Vza becomes Vza =
It is represented by α · V1. Therefore, the true drainage speed V during the span S from the upper limit to the lower limit is V = Vha +
.alpha..multidot.V1 and the discrimination timing predicting means 8 calculates the true drainage speed V (step 2).
6). Since the drainage speed from the upper limit to the lower limit is determined by the capacity of the drainage pump 2, the true drainage speed V indicates the pumping ability of the drainage pump 2 after all. Subsequently, the second cycle starts, but the discrimination timing predicting means 8 calculates the water increase speed V2 near the upper limit value as in the previous cycle (step 27). By obtaining the water increasing speed V2, it becomes possible to predict the drainage time Tx from the upper limit to the lower limit in the second cycle. That is, the discrimination timing predicting means 8 immediately calculates Tx =
The drainage time Tx is calculated using the equation (V−αV1) · T / (V−αV2) (step 28).

Next, the discrimination timing prediction means 8 calculates the count number K indicating the time interval between each discrimination timing by K
= (Tx / Ts) · (1 / M) (step 29). Here, Ts is the scan time of the present ultrasonic level sensor, for example, 150 [msec].
The value of the degree. M is the discrimination liquid level position storage means 10
, For example, a value of about 100.

Thereafter, the water surface starts to descend after reaching the upper limit value, but the discrimination timing prediction means 8 takes in the distance data from the distance calculation means 6, ie, the measured water surface position value, at the timing of each count K (step 30). ), And writes each of the measured values taken into the area corresponding to each memory address as a discrimination liquid level position (step 31). FIG.
6 is a table showing a relationship between each memory address and distance and a count number K at this time. As described above, the determination timing prediction means 8 writes the distance data, that is, the determination liquid level position in the area corresponding to each memory address of the determination liquid level position storage means 10, so that the preparation for the determination timing prediction (Step 4) is completed. .

In the above example, the discrimination liquid level position is written at the end of the second cycle. However, in order to obtain more accurate discrimination timing, the third and subsequent cycles are actually used. It is preferable to write at the end point. Further, in the above example, a half cycle until the water surface falls from the upper limit to the lower limit has been described. However, for a half cycle until the water surface rises from the lower limit to the upper limit, the determination timing is determined by the same method. Prediction preparation and prediction can be performed.

Returning to the description of FIG. 2, after step 4, it is determined whether or not the prediction preparation is completed (step 5). In this case, if not completed, the process returns to step 2 and the prediction preparation is performed again. After the prediction preparation is completed, the determination timing prediction means 8 predicts the determination timing (step 6).

FIG. 5 is a flowchart showing the contents of the timing prediction in step 6. Now, assuming that the cycle is in the n-th cycle, the discrimination timing predicting means 8 calculates the water increase speed Vn near the upper limit of the n-th cycle (step 41). By obtaining the water increasing speed Vn, it becomes possible to predict the drainage time Txn from the upper limit to the lower limit in the n-th cycle. That is, the discriminating timing predicting means 8 calculates Txn = (V-αV1).
The drainage time Txn in the n-th cycle is calculated using the equation Tn-1 / (V-αVn) (step 42).
The discrimination timing prediction means 8 calculates the count Kn indicating the time interval between the discrimination timings as Kn = (Txn
The calculation is performed using the formula of (/ Ts) · (1 / M) (step 43).

Next, the discrimination timing predicting means 8 discriminates whether or not the present time is the discrimination timing (step 7). If it is the discrimination timing, the water surface position detected at this time and the discrimination liquid surface position are determined. The abnormality discriminating means 9 compares the discrimination liquid surface position stored in the storage means 10 (step 8). That is, the discrimination timing prediction means 8 sends a timing signal to the abnormality discrimination means 9 every count number Kn after the start of counting, and the abnormality discrimination means 9 discriminates the distance data from the distance calculation means 6 at the time of input of this discrimination timing signal. It is determined whether or not the distance data matches the distance data stored in the liquid level position storage means 10.

Here, it is determined whether or not the data of the two coincide with each other based on whether or not the error between the two is within a preset error ε. In this embodiment,
Assuming that the currently detected distance is L, this distance L has an error of ± 1%, and ε = ± (Ts · S / 2Tx + 0.01L).

As a result of comparing the two data as described above, the abnormality determining means 9 determines whether or not the number of non-coincidences is N1 times or more (that is, the memory address numbers in FIG. 4 are continuous). It is determined (step 9). If it is less than N1 times, it is determined whether or not the number of non-matches is N2 times (N2 <N1) or more (step 10). And
If the number of mismatches is less than N1 times and N2 times or more, the abnormality determining means 9 registers that the detected distance data is abnormal in the abnormal data storage means 11 (step 11).

Here, the determination in step 9 is for determining whether or not an inspection is being performed by an operator. That is, when the worker checks the ultrasonic level sensor, the worker removes the sensor from the mounting position, and turns the transmitting / receiving unit 3 toward the wall to determine whether the sensor is operating. In such a case, of course, the distance data obtained by the reflection of the ultrasonic wave is quite different from the data stored in the discrimination liquid level position storage means 10. Therefore, if the number of times that both data do not match is continuously equal to or greater than the preset number N1, it is considered that an inspection has been performed by a worker, and the data at this point is not registered abnormally. Things. In addition, the determination in step 10 is performed to prevent abnormal data from being registered until such a case, because abnormal data may occur momentarily due to noise or the like.

When the abnormality is registered in the abnormal data storage means 11 at step 11, the distance calculating means 6 stores the distance data of the water surface position detected at the present discrimination timing in the discrimination liquid surface position storage means 10. The stored discrimination liquid level position is output as a detection signal (step 12). Therefore, even if a deposit adheres to the inside of the cylindrical body 4 and a complete ultrasonic reception signal cannot be obtained, the detection operation can be continued without any trouble.

Further, even if the adhered substance is once adhered, the adhered substance may be removed thereafter. In this case, the abnormality determining means 9 does not perform the abnormality determination and the registration of the abnormal data storage means 11 is performed. Remove. Therefore, the distance calculating means 6 outputs the detected distance data of the water surface position as a detection signal as usual.

Although the above embodiment has been described on the assumption that the present invention is used for a wastewater treatment system in a canal, the technology of the present invention is not limited to the wastewater treatment system in a canal. It can be used for liquid level control systems in the field.

[0035]

As described above, according to the present invention, the water level in the tank installed in the sinus can be predicted with a certain degree of accuracy or more. It is possible to prevent erroneous detection due to the attached matter.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart for explaining main operations of the ultrasonic level sensor according to the embodiment of the present invention.

FIG. 3 is a flowchart for explaining the detailed contents of step 4 in FIG. 2;

FIG. 4 is a chart showing a relationship between a memory address of a discrimination liquid level position storage unit 10 in FIG. 1 and a distance and a count number.

FIG. 5 is a flowchart for explaining the detailed contents of step 6 in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 1a Inflow port 1b Drain port 2 Drain pump 3 Transmission / reception part 4 Cylindrical body 5 Receiving circuit 6 Distance calculation means 7 Display 8 Discrimination timing prediction means 9 Abnormality discrimination means 10 Discrimination liquid level position storage means 11 Abnormal data storage means 12 Distance Data 13 Write signal 14 Timing signal 15 Discrimination liquid level position data 16 Write signal 17 Abnormality discrimination signal 18 Abnormal data 19 Output signal V1 Water supply speed V2 Water supply speed Vn Water supply speed Vh Drainage speed Vha Average drainage speed Vza Average water supply speed Vza Drainage speed S span T drainage time Tx drainage time Txn drainage time K count number Kn count number Ts scan time M memory address number

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Akira Hyuga No. 4-1.8 Yushima, Bunkyo-ku, Tokyo Kaneki Denko Tokyo Branch

Claims (6)

[Claims] 1. A liquid level position is detected by an ultrasonic level sensor provided with a cylinder for limiting directivity. Based on this detection, the liquid level position of the liquid flowing irregularly into the container is determined. A liquid level control system that starts discharging the liquid to the outside of the container when a predetermined upper limit is reached and stops the discharge when the lower limit is reached. A determination liquid level position storage means in which values of a plurality of determination liquid level positions at which an abnormality determination is to be performed within the area are stored in advance, and the liquid level position of the detection target liquid level is determined by the determination. Determination timing prediction means for predicting each determination timing to reach each determination liquid level position stored in the liquid level position storage means, and each detected liquid level detected at each determination timing predicted by the determination timing prediction means; , The discriminating liquid An abnormality discrimination for comparing each discrimination liquid level position stored in the position storage means and discriminating that the data of the detected liquid surface position is abnormal when a difference between the two is larger than a predetermined value. And an output unit that outputs a detection signal when the abnormality determination unit determines that the abnormality is abnormal, using a determination liquid surface position corresponding to the determination timing as a detection liquid surface position. 2. The ultrasonic level sensor according to claim 1, wherein the abnormality determining means registers the data determined to be abnormal in the abnormal data storage means as abnormal data, and thereafter, data relating to the detected liquid level is stored. The ultrasonic level sensor deletes the registration of the abnormal data when it is no longer determined to be abnormal. 3. The ultrasonic level sensor according to claim 1, wherein a timing prediction preparation mode is set, and in this timing prediction preparation mode, the timing prediction means stops the next discharge from a discharge stop point. 1 to the point
In the case of a cycle, the liquid level moving speed and the liquid level moving time of the liquid level position in the first cycle between the upper limit value and the lower limit value are measured, and based on these measurement results, the second time The liquid surface movement time Tx in the cycle is predicted, and the liquid surface movement time Tx
From the scan time Ts and the number M of memory addresses of the discriminating liquid surface position storage means, each discriminating timing to reach each discriminating liquid surface position is calculated, and in the second cycle at each of the calculated discriminating timings An ultrasonic level sensor, wherein each liquid level position is measured, and the measured value is written as the determined liquid level position in each storage area corresponding to each memory address of the determined liquid level position storage means. 4. The ultrasonic level sensor according to claim 3, wherein said abnormality determining means determines the first set number N1 when a difference between said detected liquid level position and said determined liquid level position is equal to or greater than a predetermined value.
The ultrasonic level sensor does not perform the abnormality determination when it occurs at each of the consecutive memory addresses. 5. The ultrasonic level sensor according to claim 4, wherein the abnormality determining means determines the first set number when a difference between the detected liquid level position and the determined liquid level position is equal to or greater than a predetermined value. When an error occurs at each of the memory addresses that are continuous by a second set number N2 that is a number smaller than N1, the data of the detected liquid level position is determined to be abnormal. Ultrasonic level sensor. 6. The ultrasonic level sensor according to claim 1, wherein the liquid level control system is an in-cavity drainage treatment system that controls a water level of a drainage pit in the canal. Ultrasonic level sensor.