JP2009151436A - Alarm and method of alarming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alarm and a method of alarming, capable of accurately issuing an alarm, when COHb reaches close to alarm value, even if low-concentration CO is continued for a long time. <P>SOLUTION: A CPU 12A determines that COHb reaches the alarm value, when a time product of CO concentration detected by a gas sensor 10 or a value, according to the CO concentration exceeds a threshold, and makes the alarm generated to report to that effect. The CPU 12A stops the generation of alarm, while the maximum value of the CO concentration detected by the gas sensor 10 is lower than a first predetermined concentration. The first predetermined concentration C1 is set to a value determined by equation (1): Y1=100×M×C1/(M×C1+Z) using the alarm value Y1 of COHb, using the Haldane constant M and oxygen concentration Z. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an alarm device and an alarm method, and in particular, a gas sensor for detecting a carbon monoxide concentration, and a time product of a carbon monoxide concentration detected by the gas sensor, or a value corresponding to the carbon monoxide concentration. Determining means that determines that the carbon monoxide hemoglobin concentration in the blood has reached an alarm value when the value exceeds a threshold value, and the determination means determines that the carbon monoxide hemoglobin concentration in the blood has reached an alarm value. The present invention relates to an alarm device having an alarm generating means for generating an alarm to notify that when the alarm occurs, and the alarm method.

  When the combustion device is incompletely burned, carbon monoxide (hereinafter, CO) is generated. If the user of the combustion appliance continues to use the combustion appliance without noticing CO leakage due to incomplete combustion, the concentration of carbon monoxide hemoglobin (hereinafter referred to as COHb) in the blood reaches a dangerous level. Therefore, a method for obtaining a COHb value from a regression equation composed of CO concentration, oxygen concentration, and leakage time has been proposed (Non-Patent Document 1). The COHb value calculated by the above regression equation is shown in FIG. This regression equation is obtained from experimental values using a house rabbit in a concentration range of CO 300 ppm to 1500 ppm and a leakage time of 90 minutes. Therefore, if the leakage time exceeds 90 minutes, it becomes a value that is practically impossible, such as a negative value or a divergent value, and the COHb value cannot be obtained accurately.

Therefore, as shown in FIG. 2, the arrival time T until the CO concentration and COHb reach an alarm value (for example, 20%) is almost a straight line in a log-log graph, that is, the following equation (2): Focusing on the fact that it can be approximated, there has been proposed an alarm device that generates an alarm when the time product of the reciprocal of the arrival time until COHb corresponding to the CO concentration reaches an alarm value becomes 1 (Patent Document 1).
T = a1 · X ^−b1 (T: COHb%, X: CO concentration, a1, b1: constant) (2)

  In the case of commercial kitchens, if ventilation (20KQ or more) that matches the installation standards is performed, the CO concentration in the room will be less than 100 ppm even if the combustion appliance is incompletely burned. If the alarm for prompting ventilation is issued, it is possible to reliably prevent forgetting ventilation and to prevent the premature ringing of the alarm before COHb reaches the alarm value. However, in an actual kitchen, a small amount of CO may be generated for a long time, for example, when holding a charcoal fire in a seed fire state. The reality is that there are users.

When CO leakage at a relatively low concentration continues, it is considered that COHb is saturated at a certain value and does not increase any more, but the COHb saturation value is estimated from the regression equation described in Non-Patent Document 1. Is difficult. Therefore, when other than the regression equation described in Non-Patent Document 1 was investigated, the Coburn equation cited in the US UL standard and the like is known (Non-Patent Documents 2 and 3). The COHb saturation value for each CO concentration at an oxygen concentration of 20% was determined using the Holden constant M used (a constant indicating how many times hemoglobin is likely to bind to CO with respect to CO). Note that the Holden constant M in the expression (1) ′ is 218 times that used in the US UL standard. The results are shown in FIG.
Ymax = 100 · M · X / (M · X + Z) (Ymax: COHb saturation value%, X: CO concentration, Z: oxygen concentration, M: Holden's constant) (1) ′

As shown in the figure, for example, when the CO concentration was 223 ppm or less, COHb was saturated at less than 20%, so it was found that it did not reach 20%. On the other hand, in the alarm device described in Patent Document 1, if a low concentration CO is leaked for a long time, it is judged that COHb has reached 20% and an alarm is generated. There was a problem that it tended to sound.
“Danger of combustion in a room with low ventilation rate of household gas appliances (oxygen-deficient combustion)” (Safety Engineering Report vol.19 No.4 Report of 1980) `` Appendix A The Use of the Coburn Equation in the Design of CO Alarms '' `` Considerations of the Physiological Variables That Determine the Blood Carboxyhemoglobin Concentration in Man '' (Journal of cllnteal investigation yd 44, No 11, 1995) JP 2007-58838 A

  Therefore, the present invention pays attention to the above problems, and an alarm device and an alarm method capable of generating an alarm when COHb is close to an alarm value with high accuracy even when low concentration CO continues for a long time. It is an issue to provide.

The invention according to claim 1, which has been made to solve the above problems, includes a gas sensor for detecting a carbon monoxide concentration, a carbon monoxide concentration detected by the gas sensor, or a value corresponding to the carbon monoxide concentration, A determination means for determining that the carbon monoxide hemoglobin concentration in the blood has reached an alarm value when the time product of the blood pressure exceeds a threshold, and the determination means has increased the carbon monoxide hemoglobin concentration in the blood to an alarm value. An alarm generating means for generating an alarm to notify that when it is determined that the alarm is generated while the maximum value of carbon monoxide detected by the gas sensor is less than a first predetermined concentration. An alarm stop means for stopping the alarm generation by the means, and the first predetermined concentration C1 is a value Y equal to or less than an alarm value of the carbon monoxide hemoglobin concentration in the blood , Following expressions (1) is set to a value obtained Y1 = 100 · M · C1 / with Holden constants M and oxygen concentration Z (M · C1 + Z) ... (1)
It exists in the alarm device characterized by this.

According to the third aspect of the present invention, when the time product of the carbon monoxide concentration detected by the gas sensor or the value corresponding to the carbon monoxide concentration exceeds a threshold value, the carbon monoxide hemoglobin concentration in the blood is alarmed. In an alarm method for sequentially performing a step of determining that the value has been reached, and a step of generating an alarm that informs that when the carbon monoxide concentration in the blood has reached an alarm value by the step, Determining whether the maximum value of the carbon monoxide concentration detected by the gas sensor is less than a first predetermined concentration before generating the alarm; and the maximum value of the carbon monoxide concentration is a first predetermined value. A step of stopping the generation of the alarm while the value is less than the value, and the first predetermined concentration C1 is a value Y1 that is equal to or less than the alarm value of the carbon monoxide hemoglobin concentration in the blood, oxygen Degrees using Z is set to a value obtained by equation (1) below Y1 = 100 · M · C1 / (M · C1 + Z) ... (1)
The alarm method is characterized by that.

  According to the first and third aspects of the present invention, the alarm is stopped while the maximum value of carbon monoxide detected by the gas sensor is less than the first predetermined concentration, so that the concentration of carbon monoxide hemoglobin in the blood is reduced. Even if a low-concentration gas whose saturation value does not exceed the alarm value is continued, it is possible to prevent a quick ringing without generating an alarm.

  The invention according to claim 2 is a storage means in which a relationship between a carbon monoxide concentration in a predetermined oxygen concentration and an arrival time until a carbon monoxide hemoglobin concentration in blood reaches the alarm value is stored in advance, The arrival time corresponding to the carbon monoxide concentration detected by the gas sensor from the time when the carbon monoxide concentration detected by the gas sensor exceeds the second predetermined concentration from the relationship stored in the storage means to the current time. Integrating means for obtaining a time product of the reciprocal number, and when the determination means has a time product of the reciprocal time of the arrival time obtained by the integrating means exceeds a threshold value, the monoxide in the blood It exists in the alarm device of Claim 1 set so that it may be judged that the carbon hemoglobin density | concentration reached the alarm value.

  According to the second aspect of the present invention, the determination means determines that the carbon monoxide hemoglobin concentration in the blood has reached the alarm value when the time product of the reciprocal of the arrival time obtained by the integration means exceeds the threshold value. Therefore, it is easy to generate an alarm when the carbon monoxide hemoglobin concentration in the blood reaches the alarm value without using the complicated regression equation to calculate the carbon monoxide hemoglobin concentration in the blood. be able to.

  As described above, according to the first and third aspects of the invention, even if a low-concentration gas in which the saturation value of the carbon monoxide hemoglobin concentration in the blood does not exceed the alarm value continues, no alarm is issued. Since early sounding can be prevented, even when low concentration CO continues for a long time, an alarm can be generated at a time when COHb is close to the alarm value with high accuracy.

  According to the second aspect of the present invention, an alarm is simply issued when the carbon monoxide hemoglobin concentration in the blood reaches the alarm value without using the complicated regression equation to obtain the carbon monoxide hemoglobin concentration in the blood. Since it can generate | occur | produce, the alarm according to the influence condition with respect to the human body of carbon monoxide can be performed easily and correctly.

  The alarm device and alarm method of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of an alarm device that implements the alarm method of the present invention. As shown in the figure, the alarm device includes a gas sensor 10. As the gas sensor 10, for example, an electrochemical sensor in which a current corresponding to the CO concentration flows by an oxidation reaction of carbon monoxide (hereinafter referred to as CO) is used. The data is output to the computer (μCOM) 12.

  The μCOM 12 is a central processing unit (hereinafter referred to as CPU) 12A that performs various processes according to a processing program, a ROM 12B that is a read-only memory that stores a program for processing performed by the CPU 12A, and various processing steps in the CPU 12A. A RAM 12C, which is a readable / writable memory having a work area to be used, a data storage area for storing various data, and the like, are connected by a bus line.

  CPU12A mentioned above takes in the output of the gas sensor 10, and detects CO density | concentration. The alarm device further includes a speaker 13 that outputs a CO leakage alarm and a voice alarm output circuit 14 that drives the speaker 13. The voice alarm output circuit 14 is controlled by the CPU 12A.

  Next, the alarm principle of the alarm device described above will be described below with reference to FIG. FIG. 2 is a log-log graph showing the relationship between the CO concentration in an oxygen concentration of 20% and the arrival time until the carbon monoxide hemoglobin concentration (hereinafter referred to as COHb) in the blood reaches 20%. As shown in FIG. 2, for example, when the oxygen concentration is 20%, COHb = 20% after 30 minutes if 300 ppm of CO continues to leak, and 20% if 400 ppm of CO continues to leak. After minutes, COHb = 20%.

As is clear from FIG. 2, the arrival time decreases exponentially as the CO concentration increases. That is, the relationship between the CO concentration and the arrival time until COHb reaches 20% can be expressed by an exponential function or a logarithmic function as shown in the following equations (2) and (2) ′.
T = a1 · X ^−b1 (T: arrival time, X: CO concentration, a1, b1: constant) (2)
LogT = −b1 · LogX + Loga1
= −b1 · LogX + c (∵Loga1 = c) (2) ′

  Next, in the present embodiment, a case where a CO leakage alarm is generated when the oxygen concentration is assumed to be 20% and COHb = 20% (alarm value) will be described. In this case, an index as shown in the above formulas (2) and (2) ′ representing the relationship between the CO concentration in the oxygen concentration of 20% as shown in FIG. 2 and the arrival time until COHb reaches 20%. A function expression or a logarithmic function expression is stored in advance in, for example, the ROM 12B (= storage means). Next, the relationship between the reciprocal of the arrival time and the time product corresponding to the CO concentration detected by the gas sensor 10 and the CO concentration will be described. First, when a leakage of 300 ppm occurs, the arrival time corresponding to this CO concentration is about 30 minutes as shown in FIG. Therefore, the reciprocal is 1/30, and the reciprocal / time product increases with a slope of 1/30 as shown in FIG. If 300 ppm leakage continues for 10 minutes, the reciprocal / time product is 10/30.

  Thereafter, when the CO concentration changes to 200 ppm, the arrival time corresponding to this CO concentration is about 50 minutes, as shown in FIG. Therefore, the reciprocal becomes 1/50, and the reciprocal / time product increases at a slope of 1/50 smaller than the slope 1/30 at the time of leakage of 300 ppm, as shown in FIG. If 200 ppm leakage continues for 3 minutes, the reciprocal / time product is (10/30 + 3/50). Furthermore, when the CO concentration changes to 400 ppm, the arrival time corresponding to this CO concentration is about 20 minutes, as shown in FIG. Accordingly, the reciprocal is 1/20, and the reciprocal / time product is increased with a slope of 1/50 of the leakage time of 200, 300 ppm and a slope of 1/20 larger than 1/30, as shown in FIG.

  As is clear from this, the reciprocal / time product described above increases more rapidly as the CO concentration is higher, and gradually increases as the CO concentration is lower. That is, the current reciprocal / time product corresponds to the current COHb for COHb = 20%. Therefore, when the current reciprocal / time product reaches 1, it can be determined that COHb is 20%. The relationship between the reciprocal and time product of arrival time T and COHb described above is described in Japanese Patent Application Laid-Open No. 2007-58838, and detailed description thereof is omitted here. Thus, an alarm can be generated when COHb reaches 20% without directly calculating COHb using a complicated high-order regression equation.

However, in the alarm method based on the reciprocal / time product described above, when a relatively high concentration of CO leaks, an alarm can be generated when COHb = 20% is accurately reached. However, when CO leakage at a relatively low concentration continues, COHb is considered to saturate at a certain value and not increase further. Therefore, the COHb saturation value for each CO concentration at an oxygen concentration of 20% was determined using the Holden constant of equation (1) ′. In the present embodiment, the Holden constant M in the expression (1) ′ is 218 times that used in the US UL standard. The results are shown in FIG.
Ymax = 100 · M · X / (M · X + Z) (Ymax: COHb saturation value%, X: CO concentration, Z: oxygen concentration, M: Holden's constant) (1) ′

As shown in the figure, it was found that when the CO concentration was less than 223 ppm, COHb was saturated at less than 20% and therefore did not reach 20%. Therefore, as shown in the following formula (1), the CPU 12A substitutes the alarm value Y1 for the COHb saturation value% Ymax of the formula (1) ′, 218 for the Holden constant M, and the CO concentration when 200000 is substituted for the oxygen concentration Z. X is set as the first predetermined density C1. When the alarm value Y1 is 20%, the first predetermined concentration C1 is set to 223 ppm.
Y1 = 100 · M · C1 / (M · C1 + Z) (1)

  Then, the CPU 12A stops generating the alarm so that no alarm is generated even if the reciprocal / time product exceeds 1, while the maximum value of the CO concentration detected by the gas sensor 10 is less than 223 ppm (first predetermined concentration). .

  The detailed operation of the alarm device described above will be described below with reference to the flowchart showing the processing procedure of the CPU 12A in FIG. First, when power is supplied to the alarm device, the CPU 12A detects the CO concentration using the gas sensor 10 (step S1). Next, when the CO concentration detected in step S1 exceeds the second predetermined concentration C2 (Y in step S2), the CPU 12A functions as an integrating means, integrates the reciprocal of the arrival time T corresponding to the CO concentration, and performs the reciprocal / A time product Σ (1 / T) is obtained (step S3). The second predetermined concentration C2 is set to a value that can be regarded as causing CO leakage.

  In step S <b> 3, the CPU 12 </ b> A detects the CO concentration at regular intervals t using the gas sensor 10. Then, for example, the exponential function expression of the above equations (2) and (2) ′ showing the relationship between the CO concentration in the oxygen concentration of 20% stored in advance in the ROM 12B and the arrival time until COHb becomes 20%. Substituting the detected CO concentration into the logarithmic function equation, the arrival time Tn corresponding to the current CO concentration is obtained. Thereafter, a value t / Tn obtained by multiplying the previously calculated reciprocal / time product Σ (1 / T) by the constant interval t and the reciprocal 1 / Tn of the arrival time Tn is added to the current reciprocal / time product Σ ( 1 / T).

  Next, the CPU 12A functions as a determination unit, and if the inverse number / time product Σ (1 / T) obtained in step S3 is less than a threshold A (for example, 1) (N in step S4), COHb reaches 20%. If it is determined that it is not, the process returns to step 3 to continue the reciprocal integration.

  On the other hand, the CPU 12A functions as a determination unit. If the reciprocal / time product Σ (1 / T) is equal to or greater than the threshold A (Y in step S4), the CPU 12A determines that COHb has reached 20%, and Proceed to step S5. In step S5, it is determined whether or not the maximum value of the CO concentration detected by the gas sensor 10 from the start of integration of the reciprocal of the arrival time T is equal to or higher than a first predetermined concentration C1 (for example, 223 ppm described above). .

  If the maximum value of CO is greater than or equal to the first predetermined concentration C1 (Y in step S5), the CPU 12A determines that COHb has reached 20%, and functions as an alarm generating means. A CO leakage signal is output (step S6), and the process ends. In response to this CO leakage signal, the audio alarm output circuit 14 controls the speaker 13 to generate an alarm indicating CO leakage.

  On the other hand, if the maximum value of CO is less than the first predetermined concentration C1 (N in Step 5), it is determined that CO leakage at a low concentration has continued and COHb has not reached 20%, and the process returns to Step S3. To continue the reciprocal integration. That is, the CPU 12A functions as an alarm stop unit, and stops generating an alarm while the maximum value of the CO concentration detected by the gas sensor 10 is less than the first predetermined value C1.

  According to the alarm device described above, the alarm is stopped while the CO detected by the gas sensor 10 is less than the first predetermined concentration (223 ppm), so that the COHb saturation value does not exceed the alarm value (20%). Even if a low-concentration gas continues, it is possible to prevent an early sound without issuing an alarm. For this reason, even when low concentration CO continues for a long time, an alarm can be generated with high accuracy when COHb is close to the alarm value.

  In the embodiment described above, an exponential function expression and a logarithmic function expression indicating the relationship between the leakage time of each CO concentration and COHb are stored. However, when the index calculation and logarithmic calculation are difficult due to the performance of the CPU 12A, the above exponential function expression and logarithmic function expression are approximated by a combination of several linear functions, and the arrival time with respect to the CO concentration is determined by the approximate expression. It is also possible to ask for Further, a table indicating the relationship between the leakage time of each CO concentration and COHb may be stored.

  In the above-described embodiment, an electrochemical type gas sensor is used. However, the gas sensor used in the present invention is not limited to the electrochemical type, and may be, for example, a semiconductor type or a catalytic combustion type as long as it detects CO.

  In the above-described embodiment, it is desired to determine whether or not COHb has reached 20% depending on whether or not the reciprocal / time product Σ (1 / T) exceeds the threshold A (1). It is not limited to. For example, the time obtained by multiplying the difference obtained by subtracting the current reciprocal / time product Σ (1 / T) from 1 and the arrival time corresponding to the current CO concentration corresponds to the remaining time until COHb reaches 20%. Therefore, as a method of determining whether or not COHb has reached 20% based on the reciprocal / time product Σ (1 / T), a difference obtained by subtracting the current reciprocal / time product Σ (1 / T) from 1 is used. The time obtained by multiplying the arrival time corresponding to the current CO concentration is set as the delay time, and when the delay time becomes zero, the reciprocal / time product Σ (1 / T) exceeds the threshold A and COHb is 20%. A method of determining that the situation has become possible is also conceivable. Further, as in the past, COHb may be calculated based on whether or not the time product of the CO concentration has exceeded a threshold value, and it may be determined whether or not it has reached 20%.

  In the above-described embodiment, the first predetermined concentration C1 is set to a value obtained by substituting the alarm value (20%) Y1 for the COHb saturation value Ymax obtained by the equation (1) ′. It is not limited to. For example, the first predetermined concentration C1 may be set to a value obtained by substituting a value Y1 smaller than the alarm value for the COHb saturation value Ymax in the above formula (1) ′.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

It is a circuit diagram which shows one Embodiment of the alarm device which implemented the alarm method of this invention. It is a log-log graph which shows the relationship between CO concentration in oxygen concentration 20%, and the arrival time until COHb becomes 20%. It is a time chart which shows the relationship between CO density | concentration and a reciprocal number / time product. It is a graph which shows the relationship between CO density | concentration and COHb saturation value when Holden's constant is 218 times and oxygen concentration is 20%. It is a flowchart which shows the process sequence of CPU which comprises the alarm device shown in FIG. It is a graph which shows the relationship between the leakage time with respect to each CO density | concentration calculated | required from the regression formula shown by the nonpatent literature 1, and COHb%.

Explanation of symbols

10 Gas sensor 12A CPU (judgment means, alarm generation means, alarm stop means, integration means)
12B ROM (storage means)

Claims (3)

Carbon monoxide hemoglobin in blood when the time product of a gas sensor for detecting the carbon monoxide concentration and the carbon monoxide concentration detected by the gas sensor or a value corresponding to the carbon monoxide concentration exceeds a threshold value Judgment means for judging that the concentration has reached an alarm value, and alarm generation means for generating an alarm for notifying that when the judgment means judges that the carbon monoxide hemoglobin concentration in the blood has reached the alarm value In an alarm device having:
An alarm stop means for stopping the alarm generation by the alarm generation means while the maximum value of carbon monoxide detected by the gas sensor is less than a first predetermined concentration; and
The first predetermined concentration C1 is set to a value obtained by the following equation (1) using a value Y1, a Holden constant M, and an oxygen concentration Z that are not more than an alarm value of the carbon monoxide hemoglobin concentration in the blood. Y1 = 100 · M · C1 / (M · C1 + Z) (1)
An alarm device characterized by that. Storage means for storing in advance the relationship between the carbon monoxide concentration in the predetermined oxygen concentration and the arrival time until the carbon monoxide hemoglobin concentration in the blood reaches the alarm value;
The arrival time corresponding to the carbon monoxide concentration detected by the gas sensor from the time when the carbon monoxide concentration detected by the gas sensor exceeds a second predetermined concentration from the relationship stored in the storage means to the present time. Integrating means for determining the reciprocal time product, and
The determination means is set to determine that the concentration of carbon monoxide hemoglobin in the blood has reached an alarm value when the time product of the reciprocal of the arrival time obtained by the integration means exceeds a threshold value. The alarm device according to claim 1. A step of determining that the carbon monoxide hemoglobin concentration in the blood has reached an alarm value when the time product of the carbon monoxide concentration detected by the gas sensor or a value corresponding to the carbon monoxide concentration exceeds a threshold value And a step of generating an alarm to notify that when it is determined that the carbon monoxide concentration in the blood has reached an alarm value by the above steps,
Determining whether the maximum value of the carbon monoxide concentration detected by the gas sensor is less than a first predetermined concentration before generating the alarm;
Sequentially performing the step of stopping the generation of the alarm while the maximum value of the carbon monoxide concentration is less than a first predetermined value; and
The first predetermined concentration C1 is set to a value obtained by the following equation (1) using a value Y1, a Holden constant M, and an oxygen concentration Z that are not more than an alarm value of the carbon monoxide hemoglobin concentration in the blood. Y1 = 100 · M · C1 / (M · C1 + Z) (1)
An alarm method characterized by that.

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