JP3873848B2 - CO alarm - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a CO alarm that detects carbon monoxide generated by incomplete combustion of a combustion device.
[0002]
[Prior art]
Gas sensors used in conventional CO alarm devices have been proposed in various systems and shapes such as a semiconductor type, a heat ray semiconductor type, and a solid electrolyte type. As an example, in the solid electrolyte type, as shown in FIG. 7, a pair of platinum electrodes 33 are formed on both sides of a plate-like solid electrolyte 1 and both sides are covered with plate-like gas selective permeators 4 and 5 and one gas is selectively permeated. A heater 6 is formed on the surface of the body 4 and an oxidation catalyst layer 7 is provided thereon.
[0003]
[Problems to be solved by the invention]
In general, gas sensors are selectively sensitive to carbon monoxide, methane, propane, hydrogen, and the like, and are used in applications such as gas leak alarms and CO alarms. Therefore, it is required that the final safety device has high sensitivity, quick response, high reliability, high selectivity, and low power consumption.
[0004]
However, in the conventional gas sensor shown in FIG. 7, the solid electrolyte 1, the gas selective permeate 4, and the oxidation catalyst layer 7 have a large heat capacity of the plate-like chip, so that a large amount of electric power is required to maintain the sensor at the operating temperature. Therefore, a commercial power source was necessary. Therefore, the power outlet is always occupied, and it is usually installed in a very limited place such as a kitchen in a general household. However, considering the current situation in which unfortunate accidents due to poor combustion in indoor combustors such as heaters and water heaters will continue, and the widespread use of central heating due to high airtightness and high thermal insulation in houses, it is necessary to disseminate CO alarms. There is. However, it is very inconvenient to occupy a power outlet in a home full of electrical products, and it is desirable to improve the installation.
[0005]
In order to solve such a problem, a thin film gas sensor having the configuration of FIG. 8 has been proposed (Japanese Patent Laid-Open No. 2001-194339). The thin film gas sensor includes a solid electrolyte thin film 11 having oxygen ion conductivity formed on an upper surface of a heater 9 formed on a substrate 8 via an electrical insulating layer 10 and a pair of solid electrolyte thin films 11 formed on the solid electrolyte thin film 11. The electrode 12 is composed of a thin film and an oxidation catalyst layer 13 provided on one electrode 12 ′ of the pair of electrodes 12. This configuration makes it possible to reduce the heat capacity and perform pulse driving, and as a result, it has been shown that significant power saving is possible and battery driving is possible. However, all of the semiconductor type, the hot wire semiconductor type, the solid electrolyte type, and the like are heated to a predetermined temperature with a heater, and thus it is necessary to increase the pulse interval in order to maintain the battery capacity for a long period of time.
[0006]
However, when the pulse interval is large, there is a risk that the detection of CO may be delayed if CO occurs suddenly in an emergency. In order to solve this problem, a heater driving method as shown in FIG. 9 is disclosed (Japanese Patent Laid-Open No. 2001-194339). This is because the heating means operates intermittently and the pulse interval (th2) when the output of the CO sensor is higher than the first set value (h2) is lower than the first set value (h1). By making it shorter than (th1), CO is detected early in an emergency. However, even with this method, when the output of the normal CO sensor is lower than the first set value, the operation is performed with a longer pulse interval, and therefore CO detection may be delayed in the initial stage of CO generation.
[0007]
The present invention solves the above-described conventional problems, and an object of the present invention is to provide a CO alarm that can detect CO at an early stage when CO occurs and can be driven by batteries with low power consumption.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, the CO alarm device of the present invention drives a CO sensor in a pulse manner, and the CO sensor is connected to a gas meter by communication means, and a pulse interval of the CO sensor is controlled by a control signal from the gas meter. It is set as the structure which changes. By changing the pulse interval of the CO sensor according to the signal from the gas meter, the battery life when driven by the battery power source is lengthened, and at the time of abnormality, the detection timing of the CO sensor is changed, so that the abnormality is detected early. Can be detected.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 is a pulse-driven CO sensor, wherein the CO sensor is connected to a gas meter by communication means, and the pulse interval of the CO sensor is changed by a control signal from the gas meter. When the gas flow rate fluctuation pattern is memorized or learned and the gas flow rate is expected to be greater than or equal to a predetermined value, the pulse interval of the CO sensor connected by communication means is shortened, and the gas flow rate is less than or equal to the predetermined value. Since it is configured to transmit a control signal for increasing the pulse interval of the CO sensor connected by the communication means when it is expected to be, the CO sensor is only used when gas is expected to be used in normal life. The pulse interval of the CO sensor can be shortened, and the CO sensor pulse interval can be increased when less gas is expected to be used. By, avoiding the wasteful consumption of power, it is possible to achieve power saving.
[0019]
Example 1
FIG. 1 shows a block diagram of a CO alarm device in Embodiment 1 of the present invention. In FIG. 1, reference numeral 14 denotes a CO alarm, in which a CO sensor 15 is housed. A power source 16 supplies power to the control means 17 by a primary battery or a secondary battery. The control means 17 controls the CO sensor 15, performs output signal processing of the CO sensor 15, and performs processing such as sounding the alarm device 18 according to the signal state. Reference numeral 19 denotes a pulse interval control means which changes according to the output of the pulse interval of the CO sensor 15 driven in a pulse manner. A communication unit 20 receives a control signal from the communication unit 22 of the gas meter 21, transmits the control signal to the pulse interval control unit, and changes the pulse interval of the CO sensor 15 as necessary.
[0020]
Next, the configuration of the CO sensor 15 will be described with reference to FIG.
[0021]
In FIG. 2, 15 is a CO sensor. As the CO sensor 15, there are various types such as a semiconductor type, a heat ray semiconductor type, a solid electrolyte type, and a constant potential electrolytic type. In this embodiment, a solid electrolyte type is used. Reference numeral 31 denotes a heat-resistant and low-thermal-conductivity substrate, and here, quartz glass of about 2 mm × 2 mm × 0.3 mm is used. A platinum heater 32 has a resistance value set to a predetermined temperature by sputtering, electron beam evaporation or the like. Reference numeral 33 denotes an insulating film, which is formed of a thin film of an insulating material such as alumina, silica, or silicon nitride so as to cover the heater 32 by sputtering or electron beam evaporation. 34 is a solid electrolyte film formed on the insulating film 33 in a smaller area than the insulating film 33, and a solid electrolyte having oxygen ion conductivity (8% yttria-stabilized zirconia) is sputtered to about 0.4 mm × 0.00 mm. It is formed in a size of 6 mm. Any solid electrolyte having oxygen ion conductivity can be used as the solid electrolyte, but yttria-stabilized zirconia (YSZ) obtained by mixing a small amount of yttria with zirconia and calcining is relatively inexpensive and easily available. 35a and 35b are electrodes, and platinum is formed on the sensitive film by sputtering. Part of platinum may be mixed with a noble metal such as palladium, ruthenium, or rhodium. In addition, all electrode materials generally used for the solid electrolyte type can be used. Reference numeral 36 denotes a catalyst set on one electrode 35a. The catalyst 36 may be any catalyst that oxidizes and decomposes the gas to be measured. However, noble metals such as platinum, palladium, ruthenium and rhodium, oxides such as vanadium and manganese, A mixture of these mixtures supported on alumina or the like is formed by a screen printing method. In this embodiment, platinum is used for the electrodes 35a and 35b and the catalyst 36 is set on one of the electrodes 35a. However, the catalyst 36 is not used and the electrode is made of a different perovskite type complex oxide or a perovskite type. You may comprise a complex oxide and gold. Reference numeral 37 denotes a heater terminal extended from the heater 32. 38a and 38b are electrode leads for taking out the output detected between the electrodes 35a and 35b, and are connected to electrode terminals 39a and 39b for sending out a detection circuit (not shown) output signal. The electrodes, electrode leads, and electrode terminals (35a, 38a, 39a and 35b, 38b, 39b) are integrally formed of the same material. The electrode lead 38 and the electrode terminal 39 are formed outside the region of the solid electrolyte membrane 34.
[0022]
In the above configuration, power is supplied from a power source (not shown) to the heater 32 via the heater terminal 37 to heat the solid electrolyte 34 to a predetermined temperature (300 ° C. to 500 ° C.). When the solid electrolyte membrane 34 reaches a predetermined temperature, electrons are transferred at the interface between the electrodes 35a and 35b, the solid electrolyte membrane 34, and the air, and oxygen ions are generated. Here, if CO exists in the air, CO is oxidized by the oxidation catalyst 36 at the electrode 35a on which the oxidation catalyst 36 is mounted, and the CO does not reach the electrode 35a. In the other electrode 35b, CO is oxidized to CO2 on the surface of the electrode 35b. In this oxidation reaction, oxygen ions in the solid electrolyte membrane 34 are used. As a result, a difference occurs in the electrode reaction between the two electrodes, the balance of the solid electrolyte oxygen ions is lost, and a potential difference is generated between the two electrodes. By detecting this potential difference, the CO concentration can be detected. The quartz glass used for the substrate 31 has a thermal conductivity of 1.5 W / mK, which is smaller than that of the insulating film 16 (35 to 45 W / mK) and the solid electrolyte film 34 (6 W / mK). In this case, the temperature of the substrate 31 can be increased almost without increasing the temperature of the solid electrolyte membrane 34 immediately above the heater 32 and the vicinity thereof, so that the power consumption for heating can be greatly reduced. Can do. Further, since the thermal shock strength is high, the temperature can be raised to a predetermined temperature in a short time.
[0023]
With the above configuration, the temperature could be raised to 450 ° C. with an electric power of 15 mWsec. The solid electrolyte membrane 34 has oxygen ion conductivity at a predetermined temperature. That is, CO can be detected when the solid electrolyte reaches a predetermined temperature. In this embodiment, quartz glass having a low thermal conductivity is used for the substrate 31, and the solid electrolyte is also formed of a thin film. Therefore, the temperature of the solid electrolyte film 34 can be instantaneously raised to a predetermined temperature, and the heater 32 is provided. Since it can be driven in a pulsed manner and power consumption can be significantly reduced, it can be driven by a battery power source. In the configuration of this example, the temperature could be raised to 450 ° C. by energizing the heater 32 for 10 msec, and the temperature returned to room temperature in about 0.5 sec after the energization of the heater 32 was stopped. Therefore, the pulse interval can be arbitrarily set from 0.5 sec to about 30 sec, which is not problematic for normal measurement. The pulse interval of 0.5 sec can also be set to 0.5 sec or less if the CO sensor is further downsized.
[0024]
Although it is possible to drive in a pulsed manner with a semiconductor type or a heat ray semiconductor type, these methods are greatly affected by moisture adsorbed on the semiconductor surface, and when the pulse interval is large, the output is affected by the adsorbed water. It is difficult to set the pulse interval arbitrarily because it decreases and requires heating for a long time to remove moisture.
[0025]
This embodiment utilizes the feature that the pulse interval of the solid electrolyte type can be arbitrarily set, and provides a CO alarm device that can reliably detect an abnormality early and avoid unfortunate situations such as escape. The operation will be described below.
[0026]
(Example 2)
FIG. 3 shows a method for operating the CO alarm according to the second embodiment of the present invention.
[0027]
When the gas flow rate measured by the gas meter 21 detects a gas flow rate equal to or higher than the predetermined value V _1, the flow rate information transmitted from the communication means 22 of the gas meter 21 is received by the communication means 20 of the CO alarm device 14. Normally, the CO sensor 15 is driven with a pulse interval t ₁ , but when the flow rate information is equal to or greater than the predetermined value V ₁ , the pulse interval is shortened to t ₂ . V ₁ can be set to an arbitrary value, and when gas flows, the pulse interval may be changed from t ₁ to t ₂ . By this method, when the gas flows over a predetermined value, it is determined that the gas combustor is used, it is determined that there is a risk of CO generation, the pulse interval of the CO sensor 15 is shortened, and the detection timing is set. If CO is generated early, the danger can be detected early. When the gas flow is stopped and the gas meter 21 detects a gas flow rate equal to or lower than the predetermined value V ₁ , the communication unit 20 receives flow rate information and lengthens the pulse interval of the CO sensor 15 or sets the pulse interval to a predetermined value. It has been configured to the value t _1. When the gas flow rate of the gas meter 21 is equal to or less than the predetermined value V ₁ , it is determined that there is little risk of CO generation, and the pulse interval of the CO sensor is increased or the pulse interval is set to the predetermined value t ₁ . It is possible to avoid wasteful power consumption, save power, and use a battery power source for a long time.
[0028]
(Example 3)
FIG. 4 shows a method for operating the CO alarm according to the third embodiment of the present invention.
[0029]
The flow rate information transmitted from the communication means 22 of the gas meter 21 when the gas flow rate measured by the gas meter 21 detects an abnormal gas flow rate greater than or equal to a predetermined value V ₂ considered to be a normal usage amount is communicated by the CO alarm device 14. Received by means 20. Normally, the CO sensor 15 is driven at a pulse interval t ₁ , but when the flow rate information is equal to or greater than a predetermined value V ₂ , the pulse interval is shortened to t ₃ . By this method, when the gas flows more than the normal usage amount, it is determined that there is a high risk of CO generation, the pulse interval of the CO sensor 15 is shortened, the detection timing is advanced, and CO is generated, The danger can be detected early. Usually, since the pulse interval is made long as t ₁ , the battery life can be kept long even when a battery is used as a power source. The pulse interval may be set in combination with the second embodiment. In that case, t ₁ >> t ₂ ≧ t ₃ may be set.
[0030]
Further, when the gas flow rate becomes equal to or less than the predetermined value V ₂ in the gas meter 21 and no abnormality is detected, the flow rate information transmitted from the communication unit 22 is received by the communication unit 20 of the CO alarm device 14 to generate CO. It is determined that the risk is low, and the pulse interval of the CO sensor 15 is lengthened, or a control signal for transmitting the pulse interval to a predetermined value t ₂ or t ₁ is transmitted. As a result, wasteful power consumption can be avoided and power saving can be achieved, and long-term use is possible even when a battery power source is used.
[0031]
Example 4
FIG. 5 shows a method of operating the CO alarm according to the fourth embodiment of the present invention.
[0032]
When the gas valve is shut off by the gas meter, or immediately before that, a control signal for shortening the pulse interval of the CO sensor connected by the communication means is transmitted. When the gas flow rate measured by the gas meter 21 detects a gas flow rate of a predetermined value V ₃ or more which is considered to be a very abnormal use state where the gas valve (not shown) must be shut off, the gas meter 21 is shut off. Alternatively, before the interruption, the communication means 20 of the CO alarm device 14 receives the interruption information or the flow rate information transmitted from the communication means 22. Is usually driven by the CO sensor 15 pulse intervals t _1, but when the flow rate information is equal to or greater than a predetermined value V _3, to shorten the pulse interval between t _4. By this method, it is judged that there is a high risk of CO generation when the gas abnormally flows over the normal usage amount, the pulse interval of the CO sensor 15 is shortened, the detection timing is advanced, and CO is generated. If so, the danger can be detected early. In the embodiment of FIG. 5, the gas valve is shut off at a gas flow rate equal to or higher than the predetermined flow rate value V ₃ , but the same is true even when the gas flows for a long time even at a low flow rate. The pulse interval may be set in combination with the second and third embodiments. In this case, t ₁ >> t ₂ ≧ t ₃ ≧ t ₄ may be set.
[0033]
When the gas meter 21 returns to the shut-off state of the gas valve, the return information transmitted from the communication means 22 is received by the communication means 20 of the CO alarm device 14, and it is determined that the risk of CO generation is small. The sensor 15 is configured to transmit a control signal that lengthens the pulse interval or sets the pulse interval to a predetermined value t ₁ . As a result, wasteful power consumption can be avoided and power saving can be achieved, and long-term use is possible even when a battery power source is used.
[0034]
(Example 5)
FIG. 6 shows a method for operating the CO alarm according to the fifth embodiment of the present invention.
[0035]
When the gas flow rate fluctuation pattern is stored or learned by the gas meter 21 and the gas flow rate is expected to exceed the predetermined value V ₁ or the gas is expected to be used, the control information transmitted from the communication means 22 is sent to the CO alarm. Is received by the communication means 20 of the machine 14, and the pulse interval of the CO sensor 15 is shortened to t2. Further, when it is expected that the gas flow rate becomes V ₁ or less or the use of gas is stopped, the control information transmitted from the communication means 22 is received by the communication means 20 of the CO alarm device 14. A control signal for increasing the pulse interval of the CO sensor or setting the pulse interval to a predetermined value t ₁ is transmitted. In normal life, wasteful power is generated by shortening the pulse interval of the CO sensor only when the gas is expected to be used and increasing the pulse interval of the CO sensor when the gas is not expected to be used. Power consumption can be avoided.
[0036]
In the above embodiment, the case where there is one gas meter 21 and one CO alarm is described, but the same applies to the case where there are a plurality of CO alarms. In addition, when there is an object to be controlled by the communication means other than the CO alarm (for example, a gas leak alarm, a fire alarm, a crime prevention facility, etc.), an information terminal device (not shown) for controlling these pieces of information is used as a gas meter. The control signal from 21 can be received and the control information can be transmitted from the information terminal device to the CO alarm device.
[0037]
【The invention's effect】
As described above, according to the present invention, the pulse interval of the CO sensor driven in a pulsed manner is changed by the control signal from the gas meter via the communication means, so that the pulse interval is usually increased and the gas is used. It is judged that there is a risk that CO will be generated when the gas flow rate becomes abnormal, and the pulse interval is shortened and the CO sensor is driven, so that in the case of a dangerous state such as CO generation, early It is possible to reliably detect and notify. In addition, by increasing the pulse interval normally, even when a battery is used as a power source, useless power consumption can be avoided and long-term use is possible.
[Brief description of the drawings]
FIG. 1 is a block diagram of a CO alarm device according to a first embodiment of the present invention. FIG. 2 is an assembled perspective view of a CO sensor according to the first embodiment of the present invention. FIG. 4 is an operation diagram of a CO alarm device according to the third embodiment of the present invention. FIG. 5 is an operation diagram of a CO alarm device according to the fourth embodiment of the present invention. FIG. 7 is a perspective view of the main part of a conventional gas sensor. FIG. 8 is a perspective view of the main part of another gas sensor of the conventional example. FIG. 9 is an operation diagram of the gas sensor of the conventional example. ]
14 CO alarm 15 CO sensor 17 Control means 19 Pulse interval control means 20 Communication means 21 Gas meter 22 Communication means 31 Substrate 32 Heater 33 Insulating film 34 Solid electrolyte membrane 35a, 35b Electrode 36 Catalyst

Claims (1)

A pulse interval of the CO sensor is changed by a control signal from a CO sensor driven in a pulsed manner, a control means of the CO sensor, a communication means connected to the control means, and a gas meter connected to the communication means. In a CO alarm device having a pulse interval control means, a gas flow rate fluctuation pattern is stored or learned by the gas meter, and the CO sensor connected by the communication means when the gas flow rate is expected to exceed a predetermined value. A CO alarm device that transmits a control signal that shortens the pulse interval of the CO sensor and increases the pulse interval of the CO sensor connected by the communication means when the gas flow rate is expected to be a predetermined value or less .

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