JP2007263807A - Liquid level detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To discover abnormality of liquid level detection in a liquid storage part. <P>SOLUTION: The liquid level detection system 1 in the liquid storage part 2 comprises: a contact output type liquid level detection means 6 for detecting an H liquid level or an L liquid level on the basis of the change of an output state in the H liquid level or the L liquid level in the liquid storage part 2; a transmission output type liquid level detection means 7 for continuously detecting the liquid level on the basis of output corresponding to the liquid level in the liquid storage part 2; and a determination means 8 for determining whether the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7 are normal. The determination means 8 determines whether the other is normal on the basis of any one liquid level detection result out of the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid level detection system in a liquid reservoir, and more particularly to a liquid level detection system capable of finding an abnormality in liquid level detection.

The liquid storage part is provided with a liquid level detecting means for the purpose of controlling and monitoring the liquid level. As the liquid level detection means, for example, an electrode type level switch that detects a specific liquid level by a change in conduction state due to contact or non-contact between an electrode provided at a liquid level detection site of the liquid storage unit and the liquid level, etc. As described above, a contact output type liquid level detecting means for detecting the specific liquid level based on a change in the output state at the specific liquid level in the liquid reservoir is known (for example, see Patent Document 1). In addition, for example, a capacitance type level sensor that continuously detects the liquid level in the liquid reservoir based on the capacitance measured using an electrode provided at a liquid level detection site of the liquid reservoir. As described above, there is known a transmission output type liquid level detecting means for continuously detecting the liquid level in the liquid storage part (see, for example, Patent Document 2).
JP 2000-28419 A JP-A-8-327435

  By the way, in the contact output type liquid level detecting means, it may become impossible to detect the liquid level due to disconnection or the like, and it becomes impossible to control or monitor the liquid level. In addition, an error may occur between the liquid level detected by the transmission output type liquid level detection means and the actual liquid level, and the liquid level cannot be controlled or monitored accurately. There is. As described above, if an abnormality occurs in the liquid level detection in the liquid level detection means, the liquid level control or monitoring is adversely affected. Therefore, it is necessary to be able to detect the abnormality in the liquid level detection.

  The present invention has been made in view of such circumstances, and a first problem to be solved is to find an abnormality in liquid level detection in the liquid reservoir.

  The second problem to be solved by the present invention is to accurately detect the liquid level by the transmission output type liquid level detecting means.

  This invention was made in order to solve the said subject, The invention of Claim 1 is a liquid level detection system in a liquid storage part, Comprising: The output state change in the specific liquid level in the said liquid storage part A contact output type liquid level detecting means for detecting the specific liquid level, and a transmission output type liquid level detecting means for continuously detecting the liquid level based on an output corresponding to the liquid level in the liquid storage section. And determination means for determining whether or not the contact output type liquid level detection means and the transmission output type liquid level detection means are normal, the determination means includes the contact output type liquid level detection means and the It is characterized in that it is determined whether or not the other is normal based on the liquid level detection result of one of the transmission output type liquid level detection means.

  According to a second aspect of the present invention, even if the determination means according to the first aspect detects that the specific liquid level has been exceeded by the transmission output type liquid level detection means, the contact output type liquid level If the specific liquid level is not detected by the detecting means, the contact output type liquid level detecting means is determined to be abnormal, while the contact output type liquid level detecting means detects that the specific liquid level has been reached. Sometimes, if the liquid level detected by the transmission output type liquid level detection means is different from the specific liquid level, the transmission output type liquid level detection means is determined to be abnormal.

  Furthermore, the invention described in claim 3 is the liquid detected by the transmission output type liquid level detection means when the determination means according to claim 2 determines that the transmission output type liquid level detection means is abnormal. And a calibration means for calibrating the position to the specific liquid level detected by the contact output type liquid level detection means.

  According to the first aspect of the present invention, the contact output type liquid level detection means and the transmission output type liquid level detection means are provided, and the contact output type liquid level detection means and the transmission output type liquid level detection means. Among these, since the determination means for determining whether or not the other is normal based on one of the liquid level detection results, an abnormality in the liquid level detection in the liquid reservoir can be found. .

  According to the invention described in claim 2, even if the transmission output type liquid level detection means detects that the liquid level in the liquid storage part has passed the specific liquid level, the contact output type liquid If the specific liquid level is not detected by the position detection means, the determination means determines that the contact output type liquid level detection means is abnormal, and the liquid level in the liquid storage part is determined by the contact output type liquid level detection means. Even if it is detected that the specific liquid level has been reached, if the liquid level detected by the transmission output type liquid level detection means is different from the specific liquid level, the determination means is the transmission output type Since the liquid level detection means is determined to be abnormal, it is possible to find an abnormality in the liquid level detection in the liquid reservoir.

  According to the invention described in claim 3, even if an error occurs between the liquid level detected by the transmission output type liquid level detection means and the actual liquid level, the transmission output type liquid level detection means The detected liquid level can be calibrated to the correct liquid level detected by the contact output type liquid level detecting means, whereby the liquid level can be accurately detected by the transmission output type liquid level detecting means.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory view showing a configuration of an example of an embodiment of a liquid level detection system according to the present invention, and FIG. 2 is a contact output type liquid level detection means in the liquid level detection system shown in FIG. It is a figure which shows the output state of a transmission output type liquid level detection means.

  The liquid level detection system 1 shown in FIG. 1 detects the liquid level of the liquid storage unit 2, and a liquid level detection container 3 for detecting the liquid level of the liquid storage unit 2 is connected to the upper communication pipe 4 and The liquid reservoir 2 is connected via a lower communication pipe 5, and the container 3 is provided with a contact output type liquid level detection means 6 and a transmission output type liquid level detection means 7. The liquid level detection system 1 further includes determination means 8 for determining whether or not the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7 are normal.

  The contact output type liquid level detecting means 6 includes a first liquid level detecting electrode bar 9 and a second liquid level detecting electrode bar 10 installed in the container 3, and each of these liquid level detecting electrodes. It is an electrode type level switch for detecting a specific liquid level in the container 3, that is, a specific liquid level in the liquid storage unit 2 by means of the bars 9 and 10.

  The first liquid level detection electrode rod 9 has a length from the upper part of the container 3 to the H liquid level (75% liquid level in the container 3). Specifically, the H liquid level is detected based on a change in the conduction state as will be described later. The second liquid level detection electrode rod 10 has a length from the top of the container 3 to the L liquid level (25% liquid level in the container 3), and the change in the output state at the L liquid level. Specifically, the L liquid level is detected based on a change in the conduction state as will be described later. Therefore, the contact output type liquid level detection means 6 detects the H liquid level and the L liquid level as the specific liquid level in the container 3.

  Each of the liquid level detection electrode rods 9 and 10 includes a first external power supply connection terminal portion 11 and a second external power supply connection terminal portion 12 that protrude to the outside of the container 3 on one end side. The first liquid level detection electrode part 13 and the second liquid level detection electrode part 14 projecting to the other end side are provided. Each of the external power connection terminal portions 11 and 12 is connected to one of the first power supply 15 and the second power supply 16, respectively. The other of the power supplies 15 and 16 is connected to the container 3. The first detection circuit 17 having the first power source 15 has the first external power connection terminal portion due to the liquid in the container 3 coming into contact with the lower end of the first liquid level detection electrode portion 13 when energized. The first liquid level detection unit that detects that the liquid level in the container 3 has reached the H liquid level due to a change in the conduction state between the container 11 and the container 3, and outputs this to the determination means 8. 19 is connected. Further, the second detection circuit 18 having the second power source 16 is connected to the second external power source by the liquid in the container 3 coming into contact with the lower end of the second liquid level detection electrode portion 14 when energized. A second liquid level that detects that the liquid level in the container 3 has reached the L liquid level due to a change in the conduction state between the terminal portion 12 and the container 3, and outputs this to the determination means 8. The detection units 20 are connected to each other.

  Here, the relationship between the liquid level and the change in the conduction state will be described with reference to FIG. The first detection circuit 17 that detects the H liquid level is in a non-energized state (OFF) when the liquid level is 0% or more and less than 75%, and is in a conductive state (ON) when the liquid level is 75% or more. . The second detection circuit 18 that detects the L liquid level is in a non-energized state (OFF) when the liquid level is 0% or more and less than 25%, and is energized (ON) when the liquid level is 25% or more. It becomes.

  The transmission output type liquid level detection means 7 continuously detects the liquid level based on the output corresponding to the liquid level in the liquid reservoir 2. Specifically, the transmission output type liquid level detecting means 7 includes a third liquid level detecting electrode bar 21 installed in the container 3, and the third liquid level detecting electrode bar 21 is used. This is a capacitance type level sensor that continuously detects the liquid level in the container 3 based on the measured capacitance. That is, the output corresponding to the liquid level in the liquid storage unit 2 is a capacitance and a current value to be described later. The third liquid level detection electrode rod 21 includes a third external power connection terminal portion 22 that protrudes to the outside of the container 3 and a third liquid level detection electrode portion 23 that protrudes to the inside of the container 3. Yes. The length of the third liquid level detection electrode portion 23 is set to a length that can detect at least the necessary minimum liquid level. The third external power supply connection terminal portion 22 is connected to one of the third power supplies 24. The other side of the third power source 24 is connected to the container 3. The third detection circuit 25 including the third power supply 24 includes a measurement unit 26 that measures the capacitance between the third liquid level detection electrode unit 23 and the container 3 by energization, and the measurement unit. 26 is converted into a current value, and the current value is converted into a liquid value in the liquid storage unit 2 based on a relationship between a preset current value and a liquid level in the liquid storage unit 2. A third liquid level detecting unit 27 for converting to a position is connected. Here, an example of the relationship between the liquid level and the current value will be described with reference to FIG. The current value is set to a value from 4 mA to 20 mA from a liquid level of 0% to a liquid level of 100% in the container 3. For example, a current value of 8 mA is set at the 25% liquid level, a current value of 12 mA is set at the 50% liquid level, and a current value of 16 mA is set at the 75% liquid level.

  The third detection circuit 25 is connected to a liquid level calibration unit 28 that calibrates the liquid level detected by the third liquid level detection unit 27. As will be described later, the liquid level calibration unit 28 determines the detected liquid level of the transmission output type liquid level detection means 7 when the determination means 8 determines that the transmission output type liquid level detection means 7 is abnormal. The liquid level is calibrated to the H liquid level or the L liquid level, that is, the 75% liquid level or the 25% liquid level. The liquid level calibrating unit 28 calibrates the liquid level by calibrating the current value in the third liquid level detecting unit 27 to 16 mA or 8 mA corresponding to 75% liquid level or 25% liquid level. ing. Calibration by the liquid level calibration unit 28 is performed according to a liquid level calibration command from the determination means 8.

  In the determination means 8, the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7 are normal on the basis of the liquid level detection results inputted from the respective liquid level detection sections 19, 20, 27. It is determined whether or not. Specifically, the determination unit 8 corresponds to the 75% liquid level corresponding to the H liquid level or the L liquid level by the third liquid level detection unit 27 of the transmission output type liquid level detection unit 7. When it is detected that the liquid level has exceeded 25%, the output state of the contact output type liquid level detection means 6, that is, the conduction state changes, and the first liquid level detector 19 or the second liquid level is changed. When the detection unit 20 detects the H liquid level or the L liquid level, the contact output type liquid level detection means 6 is determined to be normal. On the other hand, if there is no change in the conduction state and the H liquid level or the L liquid level is not detected, the contact output type liquid level detection means 6 is determined to be abnormal. Here, even if the liquid level detected by the third liquid level detection unit 27 exceeds the predetermined liquid level of 75% liquid level or 25% liquid level, the determination unit 8 is configured to detect the first liquid level detection unit 19. Alternatively, if the H liquid level or the L liquid level is not detected by the second liquid level detecting unit 20, the contact output type liquid level detecting means 6 is determined to be abnormal.

  In addition, when the first liquid level detection unit 19 or the second liquid level detection unit 20 detects that the determination unit 8 has reached the H liquid level or the L liquid level, If the liquid level detected by the liquid level detection unit 27 is 75% liquid level or 25% liquid level, the transmission output type liquid level detection means 7 is determined to be normal, while the 75% liquid level or If it is different from the 25% liquid level, the transmission output type liquid level detecting means 7 is determined to be abnormal. The determination means 8 outputs a liquid level calibration command to the liquid level calibration unit 28 when it is determined that the transmission output type liquid level detection means 7 is abnormal.

  Now, the operation of the liquid level detection system 1 will be described. In the liquid level detection system 1, the liquid level in the liquid reservoir 2 is detected by the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7. Then, using the detection result of either the contact output type liquid level detection means 6 or the transmission output type liquid level detection means 7, the liquid level in the liquid storage unit 2 is controlled. Further, the determination means 8 determines whether or not the other is normal based on the detection result of one of the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7. Hereinafter, the liquid level detection method by the liquid level detection means 6 and 7 and the abnormality determination method by the determination means 8 will be specifically described.

  First, the liquid level detection method by the contact output type liquid level detection means 6 will be specifically described. When the liquid level does not reach the liquid level detection electrode portions 13 and 14 of the first liquid level detection electrode rod 9 or the second liquid level detection electrode rod 10, the external power supply connection terminal portions 11 and 12 and the container 3 are in a non-conductive state. On the other hand, when the liquid level reaches the liquid level detection electrode parts 13 and 14, the external power connection terminal parts 11 and 12 and the container 3 are in a conductive state, and the liquid level detection parts 19 and 20 detect that the liquid level is H or L. The detection results of the liquid level detection units 19 and 20 are output to the determination means 8 and, for example, when the detection results are used for liquid level control of the liquid storage unit 2, a liquid level control unit (not shown). Is output.

  Next, the liquid level detection method by the transmission output type liquid level detection means 7 will be described in detail. When a current is passed between the third external power connection terminal portion 22 of the third liquid level detection electrode rod 21 and the container 3, a capacitance between the third liquid level electrode portion 23 and the container 3 is established. Is measured by the measurement unit 26, and the obtained capacitance is converted into a current value by the third liquid level detection unit 27 to detect the liquid level. The liquid level detected by the third liquid level detection unit 27 is output to the determination unit 8 and, for example, when the detection liquid level is used for liquid level control of the liquid storage unit 2, the liquid level control unit Is output.

  In the determination means 8, the detection liquid level of the third liquid level detection unit 27 is 75% liquid level or 25% liquid level, that is, until the H liquid level or the L liquid level is too high. If the H liquid level or the L liquid level is detected by the first liquid level detector 19 or the second liquid level detector 20, the contact output type liquid level detector 6 is determined to be normal. On the other hand, even if the detection liquid level of the third liquid level detection unit 27 exceeds the 75% liquid level or the 25% liquid level by a predetermined liquid level, the first liquid level detection unit 19 or the second liquid level detection unit 20 If the H liquid level or the L liquid level is not detected, the determination means 8 determines that the contact output type liquid level detection means 6 is abnormal.

  In the determination means 8, when the first liquid level detection unit 19 or the second liquid level detection unit 20 detects that the H liquid level or the L liquid level is reached, the third liquid level is detected. When the detected liquid level of the level detecting unit 27 is 75% liquid level or 25% liquid level, the transmission output type liquid level detecting means 7 is determined to be normal. On the other hand, even if the first liquid level detection unit 19 or the second liquid level detection unit 20 detects that the H liquid level or the L liquid level has been detected, the detection of the third liquid level detection unit 27 When the liquid level is not the 75% liquid level or the 25% liquid level, the determination unit 8 determines that the transmission output type liquid level detection unit 7 is abnormal.

  When the determination means 8 determines that the transmission output type liquid level detection means 7 is abnormal, the determination means 8 outputs a calibration command to the liquid level calibration section 28, and the liquid level calibration section 28 causes the third liquid level detection section 28 to output a calibration command. The current value of 27 is calibrated to 16 mA or 8 mA, and the liquid level is calibrated to 75% liquid level or 25% liquid level.

  Here, when liquid level control is performed so as to keep the liquid level in the liquid storage unit 2 at a constant liquid level (for example, 50% liquid level in the container 3), the liquid level in the liquid storage unit 2 Is forcibly varied to determine whether or not the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7 are normal.

  According to the liquid level detection system 1, the contact output type liquid level detection means 6 and the transmission output type liquid level detection means 7 are provided, and the contact output type liquid level detection means 6 and the transmission output type liquid level detection are provided. Since the determination means 8 for determining whether or not the other is normal based on the liquid level detection result of one of the means 7 is found, an abnormality in the liquid level detection in the liquid reservoir 2 is discovered. be able to.

  Further, even if an error occurs between the liquid level detected by the transmission output type liquid level detection means 7 and the actual liquid level, the detected liquid level of the transmission output type liquid level detection means is changed to the contact output type. The liquid level can be calibrated to the correct liquid level detected by the liquid level detecting means 7, whereby the liquid level can be accurately detected by the transmission output type liquid level detecting means 7.

  As mentioned above, although this invention was demonstrated by the said embodiment, of course, this invention is not restricted to the said embodiment. For example, the contact output type liquid level detection means 6 is not limited to the electrode type level switch, and detects a specific liquid level based on a change in output state at a specific liquid level in the liquid reservoir 2. Any liquid level detecting means may be used. Examples of such a liquid level detecting means include a float type level switch, an ultrasonic level switch, a capacitance level switch, a pressure level switch, and an optical level switch. Further, the transmission output type liquid level detection means 7 is not limited to the capacitance type level sensor, but may be any liquid level detection means for continuously detecting the liquid level in the liquid reservoir 2. Examples of such liquid level detection means include a float type level sensor, an ultrasonic level sensor, and a pressure level sensor.

It is a schematic explanatory drawing which shows the structure of an example of embodiment of the liquid level detection system which concerns on this invention. It is a figure which shows the output state of the contact output type liquid level detection means and the transmission output type liquid level detection means in the liquid level detection system shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid level detection system 2 Liquid storage part 6 Contact output type liquid level detection means 7 Transmission output type liquid level detection means 8 Judgment means 28 Liquid level calibration part (calibration means)

Claims (3)

A liquid level detection system in a liquid reservoir,
Based on the change in the output state at the specific liquid level in the liquid storage part, contact output type liquid level detection means for detecting the specific liquid level, and continuously based on the output corresponding to the liquid level in the liquid storage part. A transmission output type liquid level detection means for detecting the liquid level, and a judgment means for judging whether or not the contact output type liquid level detection means and the transmission output type liquid level detection means are normal. The means determines whether the other is normal based on the liquid level detection result of one of the contact output type liquid level detection means and the transmission output type liquid level detection means. Liquid level detection system.   Even if it is detected by the transmission output type liquid level detection means that the specific liquid level has passed, the determination means does not detect the specific liquid level by the contact output type liquid level detection means. When the output type liquid level detecting means determines that the specific liquid level is detected by the contact output type liquid level detecting means, on the other hand, it is detected by the transmission output type liquid level detecting means. 2. The liquid level detection system according to claim 1, wherein if the liquid level is different from the specific liquid level, the transmission output type liquid level detection means is determined to be abnormal.   The liquid level detected by the transmission output type liquid level detection means when the determination means determines that the transmission output type liquid level detection means is abnormal, and the specification detected by the contact output type liquid level detection means The liquid level detection system according to claim 2, further comprising calibration means for calibrating to the liquid level.

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