JPH02268263A - Leaking-liquid detecting apparatus - Google Patents

Abstract

PURPOSE:To ensure the detection of leaking liquid by correcting a measured value with a correcting coefficient which is computed from a standard resistance value in correspondence with the distortion of a measuring system. CONSTITUTION:The resistance value of a standard resistor 2 is measured with a measuring means 3 in correspondence with a signal from a control means 9. A correcting-coefficient operating means 5 computes a correcting coefficient based on the ratio between the known data of the resistor 2 from a first memory means 4 and the measured value. The correcting coefficient is stored in a second memory means 6. When the previous correcting coefficient is stored in the means 6, the coefficient is updated. When the means 3 has measured the resistance value of a sensor resistor 1, the measured value is sent into a sensor-resistance correcting-data operating means 7. The measured value is multiplied by the correcting coefficient stored in the means 6, and the corrected data close to the actual resistance value are computed. The presence or absence of the occurrence of the leaking of liquid is judged with leaking- liquid judging means 8. When the corrected data exceed an allowance value (a), a leaking-liquid detected signal (b) is outputted. Thus, the leaking of the liquid can be detected positively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid leakage detection device that detects the occurrence of liquid leakage using a sensor resistor whose resistance value changes upon contact with a liquid to be detected.

[Prior Art] Conventionally, as a liquid leakage detection device, a sensor resistor (Japanese Patent Publication No. 59-47256
It has been proposed to measure a change in the resistance value of this sensor resistor using a device main body, and detect the occurrence of liquid leakage based on the measurement result.

In this case, the main body of the detection device is equipped with a microcomputer. Then, the analog data of the sensor resistance is converted into digital data, arithmetic processing is performed, and a detection result is output.

[Problems to be Solved by the Invention] By the way, in the above liquid leakage detection device, the state of the analog electronic circuit remains unstable until the temperature rise inside the device reaches saturation (approximately 30 minutes) when the power is initially turned on. Because of the stability (characteristics of circuit elements change with temperature), a phenomenon occurs in which the measured sensor resistance reading value does not reflect the actual data (resistance value). Then, a detection result is output as if the sensor resistance value had increased. This increased value becomes larger as the sensor resistance increases, and this may lead to erroneous leakage detection.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid leakage detection device that can reliably detect liquid leakage even under unstable conditions of equipment at the initial stage of power-on.

[Means for Solving the Problems] To put it simply, the liquid leakage detection device of the present invention periodically reads the resistance value of a standard resistor, and detects the equipment based on the read value and known data of the standard resistor. The scale of the measurement system is determined (this is called "calibration"), thereby ensuring accurate measurement accuracy even in areas where the measurement system is unstable.

Specifically, as shown in the block diagram of FIG. 1, the liquid leakage detection device of the present invention uses a sensor resistor 1 whose resistance value changes depending on the occurrence of liquid leakage. In a device that measures changes in resistance value and detects leakage based on the measurement results, a standard resistor 2 with a known resistance value is newly connected to the detection device main body M together with the sensor resistor 1, and The main body M of the detection device is characterized by being composed of the following elements (a) to (g).

(a) When the standard resistance measurement signal is emitted, select the standard resistance measurement mode and measure the resistance value of the above standard resistor 2, and when the sensor resistance measurement signal is emitted, select the sensor resistance measurement mode and Measuring means 3 for measuring the resistance value of the sensor resistor 1; (a) first storage means 4 for storing known data of the standard resistance 2; correction coefficient calculating means 5 for calculating a correction coefficient from the known data of the standard resistance stored in the storage means 4 of 1;
(1) A second storage unit 6 that updates and stores the correction coefficient calculated by the correction coefficient calculation unit 5; (E) The measurement value measured by the measurement unit 3 in the sensor resistance measurement mode is stored in the second storage unit 6. Sensor resistance correction data calculation means 7 calculates correction data for the sensor resistance 1 by multiplying by the stored correction coefficient; leakage occurs when the correction data calculated by the (force) sensor resistance correction data calculation means 7 exceeds the allowable value. Liquid leakage determination means 8 that outputs a detection signal; (g) Control means 9 that selectively and periodically outputs the standard resistance measurement signal and sensor resistance measurement signal; [Operation] In the liquid leakage detection device configured as described above, , the measuring means 3 measures the resistance value of the sensor resistor 1 or the standard resistor 2 in response to a signal sent from the control means 9.

When the resistance value of the standard resistor 2 is measured, the correction coefficient calculating means 5 calculates the correction coefficient by calculating the ratio between the known data of the standard resistor 2 retrieved from the first storage means 4 and the measured value. Then, the calculated correction coefficient is stored in the second storage means 6. If the previous correction coefficient is stored in the second storage means 6, it is updated.

Next, when the resistance value of the sensor resistor 1 is measured, the measured value is sent to the sensor resistance correction data calculation means 7.

Then, the calculation means 7 multiplies the measured value by a correction coefficient stored in the second storage means 6 described above to calculate correction data substantially close to the actual resistance value.

Then, the liquid leakage determination means 8 determines whether or not a liquid leakage has occurred based on the calculated correction data, and outputs a liquid leakage detection signal when the correction data exceeds an allowable value.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 2 to 5.

In the liquid leakage detection device of the embodiment, a microcomputer 10 mounted on a device main body M is connected to a sensor resistor l and a standard Resistor 2 is connected. The selection means 12 selects either the sensor resistor 1 or the standard resistor 2 based on a signal from the microcomputer 10.

The microcomputer 10 then reads the selected resistance value. In addition, the microcomputer 10 includes
A counter 13, a timer 14, and a clock 15 are provided.

To describe the relationship between each of the above-mentioned means and this embodiment, the microcomputer 10 has the measuring means 3 shown in FIG.
, first storage means 4, correction coefficient calculation means 5, second storage means 6, sensor resistance correction calculation means 7, leakage determination means 8, and control means 9. The selection means 12 constitutes a part of the measurement means 3.

In the liquid leakage detection device of the embodiment, the following processing is performed by the action of the microcomputer 10.

When the power is turned on, the microcomputer 10 constantly measures the resistance value of the sensor resistor 1 and monitors its changes as part of the leakage detection work (steps 104 to 1o8 in FIG. 3).
However, between these operations, the resistance value of the standard resistor 2 is periodically read and calibration (scale review operation) is executed. In other words, during a period of about 30 minutes after the power is turned on when the device performance is unstable, it is necessary to perform a short-cycle calibration called the initial calibration.
Step 110 in the figure), and after that, when the device performance is stable, a long-period normal calibration is performed (step 130 in Figure 3) to stabilize the measurement accuracy.

Initial calibration (step 110) is
The procedure shown in FIG. 4 is followed, and one process is thus completed. In this process, three types of current ranges (0,5 m
A, 0.25mAS0.125mA), measure the voltage across the standard resistor 2 and read the voltage value as the resistance value. First, select Q and 5mA range as condition settings (step 111), measure standard resistance 2 four times, and calculate the average value of the remaining two data other than the maximum and minimum data ( Steps 112.113).

Next, the 0.25 mA range is selected as a condition setting, and the average of the measured values of the standard resistor 2 is obtained in the same way (steps 114, 115, and 116). Furthermore, 0.125mA
Select the range of and similarly calculate the average value of standard resistance 2 (steps 117, 118, and 119).

Finally, the known data of the standard resistor 2 is indelibly stored in the memory of the microcomputer 10 (this data is stored as a predetermined digital count number. For example, as the standard resistor 2, a resistance of 15 Ω is When using , the correction coefficient for each range is calculated by dividing 30,000 counts) by the average value of the above-mentioned measured values, and this is updated and stored. (Step 120).

In addition, during normal calibration, as shown in the flowchart in Figure 5, standard resistance 2
Measure the resistance value, calculate the average value, calculate and store the correction coefficient (steps 131, 132, 133, 134)
.

The above initial calibration is performed using sensor resistance 1
In between the measurements, the measurement is performed 5 times at 1-minute intervals, then 5 times at 2-minute intervals, and then 5 times at 4-minute intervals. Then, based on the correction coefficient obtained in each calibration, the measurement data until the next calibration is corrected.

The overall flow will be explained using FIG.

When the power is turned on, the process shown in FIG. 3 is executed according to a predetermined program. At the same time as the start, the timer and counter are reset, and the judgment in step 101 is NO1.
If the determination in step 102 is YES, the first initial calibration is performed (step 110). Then, in step 121, it is counted that the initial calibration has been performed once while holding the correction coefficient.
), the timer measures the interval until the next initial calibration (steps 121 and 122).

Always use step 1 when not performing calibration.
Steps 04 to 108 are executed. In other words, measure the resistance value of sensor resistor 1 four times, find the average value of the remaining two data excluding the maximum and minimum, and calculate the correction data by multiplying the average value by the correction coefficient found in calibration. , save this in a register etc. as a regular sensor resistance value (. Then, compare it with the previous data to detect the trend of change, and detect leakage when the resistance value exceeds the allowable value. It determines whether liquid has occurred and outputs a liquid leakage detection signal.

Initial calibration 110 is performed periodically as described above, 5 times at 1-minute intervals, 5 times at 2-minute intervals, and 5 times at 4-minute intervals (steps 124.125.126.127).
. After that, perform normal calibration at 10 minute intervals (steps 130, 135, 136), calculate the correction coefficient in the same way, correct the measured value of sensor resistance 1, and read it as regular data. .

According to this liquid leakage detection device, the measured value of the sensor resistance 1 is corrected by constantly calculating a correction coefficient suitable for the current state of the measurement system through periodic calibration. Therefore, even if the measurement system is in an unstable state, leakage can be detected reliably.

[Effects of the Invention] As explained above, the liquid leakage detection device of the present invention periodically reads the resistance value of the standard resistor, calculates a correction coefficient according to the deviation of the measurement system, and then reads the sensor resistance. Since the measured value is sometimes corrected using the correction coefficient and the corrected value is used as regular data, the value of the sensor resistance can always be read correctly even when the measurement system is in an unstable situation.

Therefore, liquid leakage detection can be performed reliably even at the initial stage of power-on.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of a liquid leakage detection device of the present invention, Fig. 2 is a schematic configuration diagram of a liquid leakage detection device of an embodiment of the invention, and Fig. 3 shows the operation details of the device of the embodiment. Flowcharts for explanation, FIGS. 4 and 5 are flowcharts showing the contents of subroutines in the flowchart of FIG. 3. 1...Sensor resistance, 2...Standard resistance,
3... Measuring means, 4... First storage means, 5... Correction coefficient calculation means, 6...
Second storage means, 7...Sensor resistance correction data calculation means,...Leakage determination means, 9...Control means.

Claims (1)

[Scope of Claims] A leakage system that uses a sensor resistor whose resistance value changes depending on the occurrence of liquid leakage, measures the change in the resistance value of this sensor resistance using a detection device main body, and detects the occurrence of liquid leakage based on the measurement result. In the liquid detection device, a standard resistor with a known resistance value is connected to the device main body together with the sensor resistor, and the device main body is configured to perform the following (a) to (
A liquid leakage detection device characterized by being composed of the elements g). (a) When the standard resistance measurement signal is emitted, select the standard resistance measurement mode and measure the resistance value of the above standard resistor, and when the sensor resistance measurement signal is emitted, select the sensor resistance measurement mode and measure the resistance value of the above-mentioned standard resistor. Measuring means for measuring the resistance value of the resistor; (a) a first memory means for storing known data of the standard resistance; (c) a measurement value measured by the measuring means in the standard resistance measurement mode and the first memory; Correction coefficient calculation means for calculating a correction coefficient from known data of the standard resistance stored in the means; (d) Second storage means for updating and storing the correction coefficient calculated by the correction coefficient calculation means; (e) The above-mentioned (f) sensor resistance correction data calculation means for calculating sensor resistance correction data by multiplying the measurement value measured by the measurement means in the sensor resistance measurement mode by the correction coefficient stored in the second storage means; (f) the sensor; Liquid leakage determination means that outputs a liquid leakage detection signal when the correction data calculated by the resistance correction data calculation means exceeds an allowable value; (g) selectively and periodically outputs the standard resistance measurement signal and sensor resistance measurement signal Control means to output;