JP2014035300A - Portable type gas detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which a conventional gas detector is provided with a bar graph LED, a pointer, a digital display, and the like, and the displays display instantaneous gas concentration when measured but not gas concentration in the past, so that time series changes of the gas concentration need to be checked by a user according to his/her memory or record.SOLUTION: A portable type gas detector 10 is provided with the following elements: (a) a gas detection element 12 which measures gas concentration and transmits a gas concentration signal; (b) a control unit 16 which receives the gas concentration signal and generates a display signal about the gas concentration and a measurement time; (c) a display 13 which receives the display signal and displays a time series graph of the gas concentration; and (d) a power supply 18 (a battery) for driving the gas detection element 12, the control unit 16, and the display 13.

Description

  The present invention relates to a portable gas detection device that measures a gas concentration in an atmosphere. All of the portable gas detection devices of the present invention are suitable for detecting gases such as hydrogen, oxygen, carbon monoxide, carbon dioxide, propane, butane, and methane. The portable gas detector of the present invention has a size and weight that can be easily carried, and has a built-in power supply (battery).

  Various gas detection devices have been developed. In the oxygen concentrator of the prior art document 1 (Japanese Patent Laid-Open No. 2001-129089), the oxygen concentration is displayed by a bar graph LED. The bar graph LED is a one-dimensional display and displays the instantaneous oxygen concentration at the time of measurement. The bar graph LED does not display the past oxygen concentration. Therefore, the time-series change of the oxygen concentration is confirmed by the user by storage or recording.

  In the gas leak monitoring device of the prior art document 2 (Japanese Patent Laid-Open No. 6-258174), the pressure of LP gas is displayed with a pointer on the scale plate. The pointer displays the LP gas pressure at the moment of measurement. The past LP gas pressure is not displayed on the pointer. Therefore, the time-series change of the LP gas pressure is confirmed by the user through storage or recording. The gas leak monitoring apparatus of the prior art document 2 can also record the time series change of the LP gas pressure on the chart paper. However, the self-recording recorder that records on the chart paper is a stationary type and not a portable type.

  In the gas alarm device of Prior Literature 3 (Japanese Patent Laid-Open No. 2011-70553), the carbon monoxide concentration is constantly measured, and the measured value is always digitally displayed regardless of whether it is normal or abnormal. The carbon monoxide concentration displayed digitally is the instantaneous concentration at the time of measurement, and the past carbon monoxide concentration is not displayed. Therefore, the time series change of the carbon monoxide concentration is confirmed by the user through storage or recording.

JP 2001-129089 A JP-A-6-258174 JP 2011-70553 A

  A conventional gas detection device includes a bar graph LED, a pointer, a digital display, and the like. These indicators display the instantaneous gas concentration at the time of measurement, but do not display the past gas concentration. Therefore, the user must confirm the time-series change of the gas concentration by storing or recording.

  Some conventional gas detection devices can record time-series changes in gas pressure on recording paper. However, self-recording recorders that record on recording paper are stationary and not portable.

  The object of the present invention is to display a time-series change in gas concentration, which is easy to carry in size and weight, and has a built-in power source (battery) and does not have to be connected to an external power source (light line). It is to realize a portable gas detection device that can be used.

(1) The portable gas detector of the present invention includes the following elements.
(A) A gas detection element that measures a gas concentration and transmits a gas concentration signal.
(B) A control unit that receives the gas concentration signal and generates a display signal relating to the gas concentration and the measurement time.
(C) A display that receives a display signal and displays a time-series graph of gas concentration.
(D) A power source (battery) for driving the gas detection element, the control unit, and the display.
(2) The portable gas detection device of the present invention has a function of manually setting a gas concentration threshold value and a function of displaying the set threshold value on a display.
(3) The portable gas detection device of the present invention displays on the display a portion that exceeds the threshold of the time series graph in a color different from the other parts of the time series graph.
(4) In the portable gas detection device of the present invention, the scale and maximum value of the gas concentration and the measurement interval and maximum value of the measurement time displayed on the display can be manually set.
(5) In the portable gas detection device of the present invention, the scale and maximum value of the gas concentration and the measurement interval and maximum value of the measurement time displayed on the display are the measured gas concentration and the length of the measurement time. Automatically set according to
(6) The portable gas detection device of the present invention includes a warning unit that issues a warning by any one of warning light, warning sound, vibration, or any combination thereof when the gas concentration exceeds a threshold value.

  According to the present invention, it is possible to display a time-series change in gas concentration, which is easily portable in size and weight, and can be used without a built-in power source (battery) and connected to an external power source (light line). A portable gas detector was realized.

Explanatory drawing of the portable gas detection apparatus of this invention An example of a time series graph (bar graph) displayed on the display when the gas concentration is measured by the portable gas detection device of the present invention An example of a time-series graph (line graph) displayed on the display when the gas concentration is measured by the portable gas detection device of the present invention An example of an algorithm from the start of a gas concentration signal until a time series graph is displayed in the portable gas detection device of the present invention An example of automatic adjustment of gain in the portable gas detector of the present invention

  An example of the portable gas detection device 10 of the present invention will be described with reference to FIG. As shown in FIG. 1, the portable gas detection device 10 of the present invention is roughly divided into a main body 11 and a gas detection element 12. A display 13, operation buttons 14, and a warning unit 15 are provided on the front surface of the main body 11. Inside the main body 11, a control unit 16, a memory 17, and a power source 18 (battery) are provided. Since all functions of the portable gas detection device 10 of the present invention are driven by an internal power supply 18 (battery), it is not necessary to connect to a commercial power supply (electric light line) at the time of use. The display 13 is preferably a color liquid crystal display or a color organic EL display.

  The gas detection element 12 is fixed by being inserted into the main body 11, and is electrically connected to the main body 11 through a plurality of terminals 19. The gas detection element 12 can be freely attached and detached. By exchanging the gas detection element 12, the concentration of a plurality of types of gases can be measured with a single main body 11. Alternatively, when the gas detection element 12 is deteriorated, it can be replaced with a new gas detection element 12.

  The gas detection element 12 is provided with a gas measurement hole 20. The gas to be measured enters the gas detection element 12 through the gas measurement hole 20. The gas causes an electrochemical reaction with the catalyst in the gas detection element 12, and generates a signal (for example, voltage change) corresponding to the gas concentration. Examples of the gas detection element 12 include a hydrogen gas sensor described in Japanese Patent Application Laid-Open No. 2011-43410. The terminal 19 of the gas detection element 12 is electrically connected to the terminal receiver of the main body 11. A gas concentration signal from the gas detection element 12 is transmitted to the main body 11 through this connection portion.

  The operation button 14 is used to turn on / off the power supply 18, manually set the measurement interval and maximum value on the time axis (normal horizontal axis) of the display 13, manually set the scale and maximum value on the gas concentration axis (normal vertical axis), and set the threshold value. Used for setting, recalling time series graphs measured in the past, and switching between manual setting and automatic setting on the horizontal axis of the vertical axis. When the gas concentration exceeds the threshold value, the warning unit 15 warns the user that the gas concentration has exceeded the threshold value by sound, light, vibration, or the like.

  The gas concentration signal transmitted from the gas detection element 12 to the main body 11 is first input to the control unit 16. The control unit 16 calculates the gas concentration from the gas concentration signal. Next, gas concentration / measurement time pair data is created. Next, based on the pair data of the gas concentration and the measurement time, data for displaying on the display 13 a time series graph of the transition of the gas concentration over the predetermined period from the present to the past is created. Next, data for displaying a time series graph of gas concentration is stored in the memory 17 and simultaneously transmitted to the display 13. A time series graph (FIGS. 2 and 3) of the gas concentration is displayed on the display 13 by the transmitted data.

  The time series graph displayed on the display 13 is, for example, a bar graph (FIG. 2) or a line graph (FIG. 3). As shown in FIG. 2, the horizontal axis of the display 13 is usually a time axis, and the vertical axis is usually a gas concentration axis. The gas concentration axis may be displayed logarithmically as necessary. As shown in FIGS. 2 and 3, the measurement interval on the time axis (horizontal axis) is, for example, every second, and the maximum value is, for example, 25 seconds. The scale of the gas concentration axis (vertical axis) is, for example, 10 ppm, and the maximum value is, for example, 500 ppm. The data of the line graph of FIG. 3 is the same as the data of the bar graph of FIG. When the measurement time exceeds the maximum value of the display 13 (25 seconds in FIGS. 2 and 3), the old data is stored in the memory 17, the time axis is shifted, and new data is displayed on the display 13. In this way, the latest data can always be displayed. In order to reduce the use capacity of the memory 17, old data may be thinned out and stored. Further, a certain amount of old data may be discarded.

  In the portable gas detection device 10 of the present invention, the scale and maximum value of the gas concentration and the measurement interval and maximum value of the measurement time displayed on the display 13 can be manually set. Alternatively, the scale and maximum value of the gas concentration and the measurement interval and maximum value of the measurement time displayed on the display 13 can be automatically set according to the measured gas concentration and measurement time. If automatic setting is used, manual setting of the measurement range of gas concentration does not need to be performed again and again. On the other hand, according to the manual setting, the relationship between the threshold value and the measured value can be intuitively grasped by fixing the display range. In addition, when the data is out of the measurement range or display range, or conversely, the gas concentration is too low, the amplification factor of the gas concentration signal input to the main body 11 is adjusted to change to an appropriate resolution. It's okay. As for the change of the amplification factor, either manual setting or automatic setting can be used.

  In the portable gas detector 10 of the present invention, past measurement data is stored in the memory 17. Therefore, it is possible to call and refer to a past time series graph as necessary. It is not easy to always carry a large amount of data recorded on a recording sheet and retrieve it as needed. However, the portable gas detection device 10 of the present invention can search past data equivalent to that of recording paper with only a small and light main body 11.

  In the example shown in FIG. 2, the threshold is 240 ppm. The data part of the measurement time of the bar graph that exceeds the threshold is displayed, for example, as a red bar. (A portion of the bar graph that does not exceed the threshold is, for example, black.) Further, while the measured value exceeds the threshold, a warning signal such as sound, light, or vibration is issued from the warning unit 15.

  The threshold shown in FIG. 3 is also 240 ppm. The portion of the line graph that exceeds the threshold is colored, for example, red. (A portion that does not exceed the threshold is, for example, black.) While the measured value exceeds the threshold, a warning signal such as sound, light, or vibration is issued from the warning unit 15.

FIG. 4 shows an algorithm from the gas concentration signal generated by the gas detection element 12 until the time series graph is displayed on the display 13 in the portable gas detection device 10 of the present invention.
(1) When a measurement start signal is input, a plot point (origin) on the X axis (time axis) is initialized.
(2) If the set measurement time interval (for example, 1 second) has elapsed, the process proceeds. Wait if the measurement time interval has not elapsed.
(3) A gas concentration signal generated by the gas detection element 12 is acquired.
(4) A gas concentration value is calculated from the gas concentration signal.
(5) A vertical axis plot point corresponding to the gas concentration value is determined.
(6) Draw a graph on the display 13.
(7) The gas concentration value and measurement time are stored in memory in pairs.
(8) Decide whether to send the screen of the display 13 (update the page). When sending the screen, the current page (X = 0 graph) is deleted, and all data of the graph is moved to the memory. If the screen is not sent, the horizontal axis (time axis) is shifted to update the plot points.

  FIG. 5 shows an example of automatic adjustment of gain (amplification factor) in the portable gas detection device 10 of the present invention. FIG. 5A shows an example in which the measured value is too small with respect to the vertical axis, so that the gain is increased to balance the measured value with the vertical axis. When a measurement value lower than a certain set value (amplification factor switching determination value (lower limit)) continues for a certain time or longer, the gain is increased to make the graph easier to see. In the case of FIG. 5A, since the gain is 10 times, the maximum value on the vertical axis is 1000 ppm to 100 ppm (1/10 times).

  FIG. 5B shows an example in which the measured value is too large with respect to the vertical axis, and the gain is lowered to balance the vertical axis and the measured value. When a measured value higher than a certain set value (amplification rate switching determination value (upper limit)) continues for a certain time or longer, the gain is lowered to make the graph easier to see. In the case of FIG. 5B, since the gain is 1/10 times, the maximum value on the vertical axis is 1000 ppm to 10000 ppm (10 times).

  An effective method of using the portable gas detection device 10 of the present invention will be described. The portable gas detector 10 of the present invention is particularly effective for detecting a gas leak position. In general, when detecting a gas leakage position, a portable gas detection device is brought close to a portion where there is a possibility of gas leakage, and the gas concentration is measured. When the gas concentration is abnormally high, gas leakage at that location is suspected.

  In the conventional portable gas detection device, the measured gas concentration is displayed in real time in an analog or digital manner. (Past measurements are not displayed.) Therefore, while moving the portable gas detection device close to the place where there is a possibility of gas leakage, reading the measured value every moment and storing or recording the change of the measured value, the portable gas detecting device when the measured value reaches the peak The position must be determined. Due to the complexity of the procedure, it is possible that the judgment of the peak of the measurement value is wrong due to an error in storage or recording. Alternatively, if the time lag from measurement to display is long because the response speed of the gas detection element is slow, or if the response time of the gas detection element takes a long time due to a small amount of gas leakage, the peak of the measurement value may not be grasped. obtain. If the peak judgment of the measured value is wrong, the gas leak location is wrong.

  In the case of the portable gas detection device 10 of the present invention, the portable gas detection device 10 is brought close to a place where gas leakage is possible while paying attention to the time series graph of the measurement values displayed on the display 13. By looking at the time series graph of the measurement values displayed on the display 13, the peak of the measurement value can be clearly understood. Further, when the portable gas detection device 10 is moved around a portion where there is a possibility of gas leakage, it is possible to clearly grasp the time series change of the measured value. In the case of the portable gas detection device 10 of the present invention, it is not necessary to read the measurement value every moment and store or record the change in the measurement value to determine the peak of the measurement value. Because the response speed of the gas detection element 12 is slow, even when the time lag from measurement to display is long, or when the response of the gas detection element 12 takes time due to a small amount of gas leakage, the peak of the measurement value can be easily grasped. it can. Therefore, the position where the peak of the measured value is obtained is not erroneously determined. Therefore, there is no misjudgment of the gas leak location.

  Some conventional portable gas detection devices emit warning signals such as sound, light, and vibration when the measured gas concentration exceeds a threshold value. Although the warning signal is useful, the peak of the measured value cannot be determined only by the warning signal. For this reason, it is difficult to accurately find the gas leak point. Like the portable gas detection device 10 of the present invention, the combination of the time series graph displaying the change in the measured value displayed on the display 13 and the warning signal can accurately find the gas leak point and has utility value. high.

  In a poor environment where the noise and vibration are very high, the warning signal may not be detected. Even in such a case, in the portable gas detection device 10 of the present invention, when the warning signal is issued (when the gas concentration exceeds the threshold value), the color of the graph changes, so the warning signal is issued. You can see at a glance what was being done.

  Although the portable gas detection device 10 of the present invention is optimal for detection of a gas leak location, the application is not limited to detection of a gas leak location. The portable gas detection device 10 of the present invention monitors time-series changes in the gas concentration of the working atmosphere at a site where a dangerous gas (for example, hydrogen, oxygen, carbon monoxide, carbon dioxide, propane, butane, methane) is used. Also suitable for doing. In such a case, the measurement interval of the measurement time can be set longer.

  The portable gas detector 10 of the present invention is particularly effective for detecting gas leaks. In addition, the portable gas detection device 10 of the present invention is also suitable for monitoring time-series changes in the gas concentration of the working atmosphere.

DESCRIPTION OF SYMBOLS 10 Portable gas detection apparatus 11 Main body 12 Gas detection element 13 Display 14 Operation button 15 Warning part 16 Control part 17 Memory 18 Power supply 19 Terminal 20 Gas measurement hole

Claims (6)

A gas detection element for measuring a gas concentration and transmitting a gas concentration signal;
A controller that receives the gas concentration signal and generates a display signal relating to the gas concentration and measurement time;
A display for receiving the display signal and displaying a time series graph of the gas concentration;
The portable gas detection apparatus provided with the power supply for driving the said gas detection element, the said control part, and the said display. A function of manually setting a threshold value of the gas concentration;
The portable gas detection device according to claim 1, further comprising a function of displaying the threshold value on the display.   The portable gas detection device according to claim 1 or 2, wherein a portion of the time series graph that exceeds the threshold is displayed in a color different from that of the other portions of the time series graph on the display.   The portable gas detection device according to any one of claims 1 to 3, wherein the scale and maximum value of the gas concentration and the measurement interval and maximum value of the measurement time displayed on the display can be manually set.   The scale and maximum value of the gas concentration and the measurement interval and maximum value of the measurement time displayed on the display are automatically set according to the measured gas concentration and the length of the measurement time. The portable gas detection apparatus in any one of 1-3.   The portable gas detection device according to claim 4 or 5, further comprising a warning unit that issues a warning by any one of warning light, warning sound, vibration, or any combination thereof when the gas concentration exceeds the threshold value. .

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