JPH09185787A - Hc1 sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect hydrogen chloride(HC1) with the detection sensitivity that a sensor element main body originally has by exposing the sensor element to the outside air through the hole of an external cover and forming fins radially on the external cover so that the sensor element is surrounded. SOLUTION: On the surface of the external cover 10 of the HC1 sensor, a gas guide-in part 11 for efficiently gathering HC1 to the sensor element is provided. In the center part of the gas guide-in part 11, the circular hole 12 passing the sensor element 3 is bored and the six fins 13 are formed radially around the hole 12. Each fin 13 is in a sectorial shape and taller than the sensor element 3. This gas guide-in part 11 is formed of resin of low hydrophilicity such as fluorine-based resin. Then the sensor element 3 is fitted to the circuit board of a main body 14 and exposed to the outside air through the hole 12 bored in the gas guide-in part 11. Further, the external cover 10 is fixed to the main body 14 with screws 15.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an HCl sensor for detecting hydrogen chloride (HCl) which is a corrosive gas.

[0002]

2. Description of the Related Art With the development of industry, accidents due to various flammable and toxic gases and oxygen deficiency are frequently occurring. Particularly, if a corrosive gas is mixed in our living environment and working environment in an extremely small amount, it has various adverse effects on the human body and corrodes metals, etc. It causes a breakdown. An example of the case where corrosive gas is generated is abnormal heating of a power cable of an electric appliance. Power cables for electrical appliances are generally made of PVC (Polyvi
It is widely known that when PVC is heated, chlorine and hydrogen generate HCl, which is a corrosive gas, when this PVC is heated. Also, as is well known, H
Cl is a colorless gas with a pungent odor, which is very soluble in water,
It emits smoke in moist air.

As a detector for detecting this corrosive gas, HCl, for example, a crystal oscillator type HCl sensor is known. In this type of HCl sensor, a crystal oscillator is used as an oscillating element. For example, a chromium film and a gold film are laminated and vapor-deposited on the central portion of the crystal oscillator, and both ends are provided. A metal film is deposited. When this vapor-deposited metal film is corroded by HCl, its weight increases and the frequency of the crystal unit decreases. By detecting this change in frequency, HCl can be detected.

Here, FIG. 7 is a perspective view showing the appearance of a conventional HCl sensor using such a sensor element. As shown in this figure, the HCl sensor includes a main body 1 and a main body 1
A circuit board 2 provided inside, a sensor element 3 whose surface has been subjected to the above-mentioned treatment, an outer cover 4 fitted to the main body 1 to cover the circuit board 2 and the sensor element 3, and an outer cover 4.
And a metal insect screen 6 covering the detection window 5 from inside. The sensor element 3 is arranged in a detection space formed by the main body 1 and the outer cover 4. EEPR on the circuit board 2
The OM is mounted, and the initial value of the frequency of the sensor element 3 is written therein. The circuit board 2 constantly compares the rate of change of the oscillation frequency by the sensor element 3 with a reference value, and outputs a signal indicating a fire when the rate of change exceeds the reference value. In such an HCl sensor, when the power cable is heated due to a short circuit or the like to generate HCl, which enters the detection space through the detection window 5 of the outer cover 4 and the insect screen 6, the sensor element 3 The metal film deposited on the substrate is corroded, which causes the frequency of the sensor element 3 to decrease. When the rate of change of the oscillation frequency due to the frequency exceeds the reference value, the circuit board 2 outputs a signal informing of a fire.

[0005]

In the conventional HCl sensor described above, the insect repellent net 6 is provided to prevent insects and dust from entering the detection space in which the sensor element 3 is arranged. Since it is easily adsorbed on all things, it also adheres to the insect repellent net 6, and a sufficient amount of HCl for this purpose does not reach the detection space, resulting in a problem that the original detection sensitivity of the sensor element is impaired.

Therefore, an object of the present invention is to provide an HCl sensor which can detect HCl with the detection sensitivity inherent in the sensor element.

[0007]

In order to achieve the above object, the HCl sensor according to the first aspect of the present invention is provided with a sensor element whose characteristic changes when exposed to a corrosive gas. A main body and a body attached to the main body, and a hole for exposing the sensor element to the outside air is formed in a central portion, while a peripheral portion from the central portion is radially formed with the hole formed in the central portion as a center. And an outer cover formed with a plurality of fins higher than the height of the sensor element. According to this configuration, when the outer cover is attached to the main body, the sensor element is exposed to the outside air through the hole formed in the central portion of the outer cover, and the outer cover is provided with the sensor element so as to surround the sensor element. Since the fins are radially formed as the center, the generated H
Cl efficiently collects on the sensor element. Further, since the fins are arranged so as to surround the sensor element and the height of each fin is higher than that of the sensor element, a finger or the like does not hit the sensor element. Therefore, the sensor element 3 is not disabled by being touched by a finger or the like, and HCl can be detected with the original detection sensitivity of the sensor element.

According to the second aspect of the present invention, an HCl sensor has a main body provided with a sensor element whose characteristic changes when exposed to a corrosive gas, and is attached to the main body to form a detection space for the sensor element. And an outer cover having a plurality of detection windows opened along the circumferential direction, and an insect screen formed of a metal having a low ionization tendency such as gold or platinum and covering each detection window of the outer cover. Is. According to this structure, since the insect repellent net is formed of a metal having a low ionization tendency such as gold or platinum, it becomes difficult for HCl to adhere, and a sufficient amount of HCl reaches the detection space. Therefore, HCl can be detected with a sensitivity substantially close to the original detection sensitivity of the sensor element.

According to the third aspect of the present invention, an HCl sensor has a main body provided with a sensor element whose characteristic changes when exposed to a corrosive gas, and is attached to the main body to form a detection space for the sensor element. And an outer cover in which a plurality of detection windows are opened along the circumferential direction, and an insect screen formed of a resin having low hydrophilicity such as a fluororesin and covering each detection window of the outer cover. Is.
According to this configuration, since the insect repellent net is formed of a resin having low hydrophilicity such as a fluorine-based resin, it becomes difficult for HCl to adhere, and a sufficient amount of HCl reaches the detection space. Therefore, the HC is detected at a sensitivity close to the original detection sensitivity of the sensor element.
l can be detected.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. A. External Configuration of HCl Sensor FIG. 1 is a perspective view showing the external appearance of an embodiment of an HCl sensor according to the present invention. 2 is a plan view showing the appearance of the embodiment shown in FIG. As shown in FIGS.
On the surface of the outer cover 10 of the sensor, a gas introduction part 11 for efficiently collecting HCl in the sensor element 3 is provided. The sensor element 3 is provided at the center of the gas introduction part 11.
A circular hole 12 through which the holes pass is formed, and six fins 13 are radially formed around the hole 12. Each fin 13 has a fan shape, and its height is higher than that of the sensor element 3. The gas introduction part 11 is formed of a resin having low hydrophilicity such as a fluorine resin.

The sensor element 3 is attached to a circuit board (not shown) of the main body 14 and is exposed to the outside air through a hole 12 formed in the gas introducing portion 11. Outer cover 10
Is fixed to the body 14 with screws 15. in this way,
By exposing the sensor element 3 to the outside air and arranging the fins 13 radially around the sensor element 3, the generated HCl can be efficiently collected in the sensor element 3. In addition, the height of each fin 13 depends on the sensor element 3.
Since it is higher than that, it will not be disabled by being touched by a finger or the like.

B. Electrical Configuration of HCl Sensor FIG. 3 is a block diagram showing the electrical configuration of the HCl sensor. In this figure, the HCl sensor is the sensor element 3,
It is composed of an EEPROM 18, a microcontroller 19, a clock signal oscillator 20, a gate 21, a counter 22, an output 23 and a power supply 24. EEPRO
The initial value of the frequency of the sensor element 3 is written in M18. The microcontroller 19 controls each part according to a program written in its internal memory. The clock signal generator 20 is the microcontroller 1
The clock signal which is the basis of the operation of 9 is output. The gate 21 allows the signal from the sensor element 3 to pass for a certain period, and the counter 22 counts the signal passing through the gate 21. The count value counted by the counter 22 is taken into the microcontroller 19.

The microcontroller 19 has a counter 22.
The oscillation frequency of the sensor element 3 is calculated on the basis of the count value counted in step 1, and the change rate of the obtained oscillation frequency is calculated to determine whether it is a fire, insect or dust. In this case, since the change rate of the oscillation frequency is different between the case where the sensor element 3 is covered with insects and dust and the case where there is a fire, the reference value obtained in advance by experiments or the like is written in the internal memory of the microcontroller 19. . The microcontroller 19 judges the fire or insects and dust based on each reference value, outputs a signal notifying the fire through the output unit 22 when it judges that it is a fire, and informs the abnormality when judging that there is a bug or dust. Output a signal.
In addition, the microcontroller 19 compares the obtained oscillation frequency with the initial value of the frequency of the sensor element 3 written in the EEPROM 18, and the sensor element 3 is detected based on the difference.
Determine the life of the. In addition, the microcontroller 19
Monitors the power supply voltage and outputs a reset signal to each unit when it judges that the power supply voltage has dropped below a predetermined value. On the other hand, the power supply unit 24 converts a voltage (for example, 24 V) supplied from the outside into a voltage required for each circuit unit.

C. Operation of HCl Sensor FIG. 4 is a flowchart showing the operation of the HCl sensor. In this figure, first, in step S10, the oscillation frequency of the sensor element 3 is obtained. That is, the oscillation frequency of the sensor element 3 is calculated based on the count value counted by the counter 22. Then step S12
In, the oscillation frequency obtained in the previous step is compared with the initial value of the frequency of the sensor element 3. Then, it is judged from the comparison result that the sensor element 3 has reached the end of its life (step S14). In this determination, if it is determined that the sensor element 3 has reached the end of its life, the process proceeds to step S16, and a signal indicating the end of life is output. On the other hand, the sensor element 3
If it is determined that the life has not expired, the process proceeds to step S18.

In step S18, the rate of change is obtained from the oscillation frequency of the sensor element 3 obtained in the previous step and the oscillation frequency already obtained and stored. In this case, the rate of change cannot be obtained because the previous oscillation frequency has not been obtained in the first process, and therefore the processes in steps S22 and S26 described below are not performed, and the process directly proceeds to step S28. After obtaining the frequency change rate, the process proceeds to step S20, and it is determined whether or not there is a fire based on the frequency change rate obtained in the previous step. If it is determined that there is a fire in this determination, a signal notifying the fire is output in step S22. On the other hand, if it is determined that it is not a fire, the process proceeds to step S24, and it is determined whether it is insects or dust.

In this determination, if it is determined to be insects or dust, a signal notifying the abnormality is output in step S26 and the process returns to step S10. On the other hand, if it is determined that it is not insects or dust, the process proceeds to step S28, and the power supply voltage is detected. After detecting the power supply voltage, it is determined in step S30 whether the power supply voltage is a specified value or not. If it is determined that the power supply voltage is the specified value or more, it is determined as normal and no processing is performed and the process directly returns to step S10. On the other hand, if it is determined that the power supply voltage is less than or equal to the specified value, the process proceeds to step S32, a reset signal is output, and the process returns to step S10. After that, the above process is repeated.

As described above, in this embodiment, the sensor element 3 is exposed to the outside air and the fins 13 are arranged radially around the sensor element 3 as a center.
The generated HCl can be efficiently collected in the sensor element 3. Further, since the height of each fin 13 is higher than that of the sensor element 3, the sensor element 3 is not disabled by being touched by a finger or the like.

The present invention is not limited to the above-described embodiment, but various embodiments are possible within the scope of the object of the present invention. Specifically, the following may be performed. (A) As shown in FIG. 5, a partition 32 surrounding the sensor element 3 may be provided, and a suction fan 33 may be provided in a part of the partition 32. In this case, the fan 33 is rotated by the motor. This fan 33
The rotation causes the HCl to be sucked through the hole 12 through which the sensor element 3 passes. By providing the forcible suction mechanism in this way, HCl can be further collected in the sensor element 3, and HCl can be detected with the original detection sensitivity of the sensor element 3. (B) As shown in FIG. 6, the insect net 35 may be made of a metal having a low ionization tendency such as gold or platinum, or a resin having a low hydrophilicity such as a fluorine resin. In this case, a metal with a low ionization tendency or a resin with a low hydrophilicity is H
Since it is difficult for Cl to be adsorbed, a sufficient amount of HCl reaches the periphery of the sensor element 3, so that it is possible to detect HCl with a sensitivity substantially close to the original detection sensitivity of the sensor element 3.

[0019]

According to the HCl sensor of the first aspect of the present invention, the sensor element is exposed to the outside air through the hole formed in the center of the outer cover while the outer cover is attached to the main body. Since the fins are radially formed around the sensor element so as to surround the sensor element on the cover, the generated HCl efficiently collects on the sensor element, so that it is possible to detect HCl with the original detection sensitivity of the sensor element. . Further, since the height of each fin is set higher than that of the sensor element, there is no possibility that a finger or the like touches the sensor element to make it unusable.

According to the HCl sensor of the second aspect of the present invention, since the insect net is made of a metal having a low ionization tendency such as gold or platinum, it becomes difficult for the HCl to adhere and a sufficient amount of HCl reaches the detection space. Therefore, it is possible to detect HCl with a sensitivity substantially close to the original detection sensitivity of the sensor element. According to the HCl sensor of the third aspect of the present invention, since the insect repellent net is formed of a resin having low hydrophilicity such as a fluorine-based resin, it becomes difficult for the HCl to adhere and a sufficient amount of HCl reaches the detection space. It is possible to detect HCl with a sensitivity substantially close to the original detection sensitivity of the sensor element.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of an embodiment of an HCl sensor according to the present invention.

FIG. 2 is a plan view showing the outer appearance of the same embodiment.

FIG. 3 is a block diagram showing an electrical configuration of the same embodiment.

FIG. 4 is a flowchart showing an operation of the embodiment.

FIG. 5 is a plan view showing the external appearance of another embodiment of the HCl sensor according to the present invention.

FIG. 6 is a perspective view showing an exploded structure of another embodiment of the HCl sensor according to the present invention.

FIG. 7 is a perspective view showing an exploded structure of another embodiment of the conventional HCl sensor.

[Explanation of symbols]

 3 Sensor element 10 Outer cover 11 Gas introduction part 12 Hole 13 Fin 14 Main body 35 Insect repellent net

Claims (3)

[Claims] 1. A body provided with a sensor element whose characteristic changes when exposed to corrosive gas, and a body attached to this body, and a hole is formed in the center to expose the sensor element to the outside air. On the other hand, the HCl sensor is provided with an outer cover in which a plurality of fins are radially formed around a hole formed in the central portion in a peripheral portion from the central portion. 2. A main body provided with a sensor element, the characteristic of which is changed by touching corrosive gas, and a main body attached to the main body, which forms a detection space for the sensor element and which is arranged along the circumferential direction. 2. An HCl sensor, comprising: an outer cover having a detection window opened therein; and an insect net formed of a metal having a low ionization tendency such as gold or platinum and covering each detection window of the outer cover. 3. A main body provided with a sensor element, the characteristic of which changes when exposed to a corrosive gas, and a main body attached to the main body to form a detection space for the sensor element and to extend along the circumferential direction. 2. An HCl sensor, comprising: an outer cover having a detection window opened therein; and an insect net formed of a resin having low hydrophilicity such as a fluorine resin and covering each detection window of the outer cover.