JPH09155133A - Control method of air cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a rational control suited to the sense of smell characteristic of a human at a low cost by providing an air cleaner with a start means for starting the cleaner in response to an increase in the output of a gas sensor and a stop means for stopping the cleaner, if the output of the gas sensor is below a specified value for stop. SOLUTION: A specified value for start and a specified value for stop are set within a range of an output from a gas sensor S by a reference output based on the minimum value or the average value of the output from the gas sensor S to be sampled every specified time. The start means detects the contamination of an air by the indication of the output from the gas sensor S specified times the reference output and starts the cleaning function of an air cleaner at the point of time when the specified value for start is reached. The stop means compares the specified value for stop to the output of the gas sensor S or a decrease in the output of the gas sensor S, and stops the cleaning function of the air cleaner by interpreting that the air is already cleaned, in case the output of the gas sensor S is lower than the specified value for stop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a cleaning function in an air cleaner control device using a gas sensor.

[0002]

2. Description of the Related Art In recent years, with the growing interest in clean and comfortable living spaces, for example, air cleaners for purifying air in the passenger compartment or passenger compartments caused by cigarette smoke have begun to spread rapidly. Along with this, various proposals have been made regarding a control method for automatically controlling the start and stop of the air cleaner. As an example, there is a device in which a catalyst-sensitized semiconductor gas sensor that is small, easy to maintain, and has a long life is mounted on an air cleaner, and the start and stop of the cleaning function are automatically controlled based on the output of the gas sensor.

Originally, in this kind of device, among the substances contained in the cigarette smoke, a gas (for example, a malodorous substance such as ammonia or acetaldehyde) which can be purified by an air cleaner is detected by a gas sensor and removed. , It is desired to perform rational control that matches human olfactory characteristics. However, this control method has not been realized because there is no catalyst-sensitized semiconductor gas sensor showing sufficient sensitivity to the gas.

Therefore, in the present situation, a catalyst-sensitized semiconductor gas sensor which is sensitive to other coexisting gases (carbon monoxide, hydrogen, etc.) contained in cigarette smoke is used, and an air cleaner of the air cleaner is based on the output value of this gas sensor. It controls starting and stopping. However, with an air cleaner, gas components such as carbon monoxide and hydrogen can hardly be removed.Therefore, unless the gas components are forcibly removed by ventilation or a ventilation fan, the output of the gas sensor does not decrease, and stop control is extremely difficult. It was difficult.

As a solution to such a problem, for example, in Japanese Patent Publication No. 6-7897, it is impossible to stop the air cleaner only by lowering the output of the gas sensor, and the saturation of the output of the gas sensor is detected. However, there is disclosed a control method in which after the saturation is detected, a timer is used to stop the air cleaner by providing saturation detection means for continuing the operation of the air cleaner for a predetermined time. In Japanese Utility Model Publication No. 5-26416, the saturation detecting means and an output decrease detecting means for detecting a decrease in the gas sensor output during the operation of the air cleaner are provided, and the saturation detecting means and the output detecting means are provided. A method of controlling an air cleaner configured to stop the air cleaner by any of the means is disclosed. FIG. 5 is a control flowchart of the microcomputer shown in the embodiment of this publication. As can be seen from this, it is necessary to continue the operation of the air cleaner for a predetermined time after detecting the saturation. A timer means is provided to control the air cleaner.

[0006]

However, in such a control method, the output does not decrease unless the windows and doors in the room are ventilated to such an extent that the output does not decrease, and in a normal use environment in which the windows and doors are closed. The air output cleaner is not stopped by the front output decrease detecting means, but the air cleaner is stopped by the saturation detecting means using the timer means. Therefore, there is a problem that the timer is stopped and the air pollution condition cannot be dealt with even in a room having a high airtightness in which the smoke of smoke is hard to escape and in a room having a low airtightness in which the smoke of the smoke is easily removed. In addition, when the cleaning capacity deteriorates due to the deterioration of the filter of the air cleaner, the stop control by the timer is performed at the same set time as before the deterioration even though it has not been cleaned, resulting in insufficient cleaning. .
For this reason, it was not possible to deal with the change with time of the filter. On the other hand, if the timer is set to a long time so that the purification does not become insufficient, there is a problem of excessive purification.

The present invention has been made on the basis of such a point, and its object is to accurately detect the purification state by using a gas sensor capable of detecting a gas which can be purified by an air cleaner, and By performing the control that is in the purification state, the start and stop control of the air cleaner can be rationalized according to the human olfactory characteristics.
Another object is to provide an inexpensive air cleaner control method.

[0008]

In order to achieve the above object, an air cleaner control method according to the present invention is based on an output value of a gas sensor showing high sensitivity to a gas purifiable by the air cleaner. In the control method of the air cleaner that controls the start and stop, the output of the gas sensor starts to decrease due to the increase of the output of the gas sensor, and the output of the gas sensor starts to decrease, and the output of the gas sensor becomes less than the predetermined value for stop. A stop means for stopping the air cleaner at times is provided.

[0009]

The predetermined start value and the predetermined stop value are determined within a range of the output of the gas sensor by a reference output based on a minimum value or an average value of the output of the gas sensor sampled at regular intervals. The starting means is
When the output of the gas sensor becomes a predetermined multiple of the reference output, air contamination is detected, and when the predetermined value for starting is reached, the cleaning function of the air cleaner is started.

The stopping means compares the predetermined value for stopping with the output of the gas sensor or the reduced amount of the output of the gas sensor, and when the output of the gas sensor is lower than the predetermined value for stopping, the stop means outputs air. The cleaning function of the air cleaner is stopped, judging that the cleaning has been completed. At this time, it is preferable that the predetermined stop value is smaller than the predetermined start value used in the starter unit as the output of the gas sensor increases. The decrease in the output can be detected by calculating the difference or ratio between the output of the gas sensor obtained by sampling and the output of the previous gas sensor also obtained by sampling.

In the above air cleaner control method,
Only when the stopping means does not work even though the output of the gas sensor is starting to decrease, the timer operated immediately after the output of the gas sensor starts to decrease,
It is conceivable to provide a forced stop means for forcibly stopping the cleaning function of the air cleaner. This is because it is assumed that the output of the gas sensor is unlikely to change due to some influence such as temperature and humidity, and it may not reach the predetermined stop value, which serves as an auxiliary function of the stop means. For this purpose, it is necessary to set a long timer setting time.

In order for the stopping means to operate, the output of the gas sensor must be obtained so that the value becomes equal to or less than the predetermined value for stopping when the air is purified. For this reason, the gas sensor has a sensitivity (resistance value in air / ammonia gas value) expressed by a rate of change in resistance value in air and in the atmosphere of 500 ppm of ammonia so that the gas sensor can appropriately react to the purified state of air. It is preferable to use a gas sensor having a resistance value of 5 or more. Further, it is particularly preferable that the gas sensor has a ratio of the sensitivity of the ammonia to the sensitivity represented by the rate of change of the resistance value in air and in the atmosphere of hydrogen of 500 ppm of 0.3 or more.

As the gas sensor having the sensitivity of 5 or more, a catalyst-sensitized semiconductor gas sensor composed of a gas sensor containing tin oxide or indium oxide as a main component and a platinum catalyst, to which molybdenum or a molybdenum compound is added. It is considered that it is composed of. At this time, the mode of the gas sensitizer is not particularly limited, and examples thereof include those obtained by sintering tin oxide or indium oxide, and those obtained by forming tin oxide or indium oxide into a film shape (thick film or thin film). To be When the tin oxide thin film or the indium oxide thin film is used as the gas sensitive material, a gas sensor having high sensitivity to ammonia can be obtained.

By using the start and stop control of the air cleaner, the operation mode of the fan of the air cleaner is set to "
It is possible to set in steps such as "strong", "medium", and "weak", and the predetermined start value and stop predetermined value that correspond to the switching of these operation modes are equal difference or ratio. When the operation mode is set stepwise as described above, the cleaning function of the air cleaner can be gradually switched to the operation mode according to the output of the gas sensor and stopped. It is recommended that the timer is set for each operation mode and that it is activated each time a predetermined stop value for switching the operation mode is reached. It may be set shorter or longer as it gets weaker.

The control method of the air cleaner according to the present invention utilizes the output of the gas sensor according to the degree of purification of the air, and performs the cleaning function of the air cleaner when the increasing output of the gas sensor reaches the predetermined value for starting. The control is performed such that the cleaning function of the air cleaner is stopped when the output of the gas sensor, which has been lowered, reaches a predetermined stop value. Furthermore, if the output of the decreasing gas sensor does not reach the specified stop value indefinitely, the timer that has been operating since the output of the gas sensor began to decrease is used to forcibly stop the cleaning function of the air cleaner. It has a function.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a detection circuit diagram of an air cleaner control method according to this embodiment. In the figure, reference symbol S is a gas sensor, reference symbol H is a heater, reference symbol Vc is a circuit voltage, and reference symbol Vr is a load resistance, which are connected in series with the gas sensor S.
The potential difference across the load resistance Vr is taken out as the output voltage Vout, and the resistance value of the gas sensor S is changed to R
If s, the output voltage Vout can be expressed by the following equation. Vout = Vc.Vr / (Rs + Vr)

Here, in FIG. 1, the resistance values of Vc = 5V and Vr are controlled by a detection circuit adjusted so that the value of the output voltage Vout when the cigarette is not burned becomes 1.3V, and the sealed 6 tatami mat is used. Three cigarettes (manufactured by Japan Tobacco Inc., trade name: Mild Seven) were sequentially burned indoors, and then the air cleaner was activated. FIG. 2 is a diagram showing the time-output voltage characteristic of the value detected by the gas sensor at this time. In the figure, (1) shows the present embodiment, and (2) shows the comparative example.

In this embodiment, as the gas sensor S, a catalyst-sensitized semiconductor gas sensor consisting of a gas sensitive material composed of a tin oxide thin film having a mass film thickness of 150 Å and a platinum catalyst having a mass film thickness of 20 Å is used, and a gas film having a mass film thickness of 200 Å is used. A structure having molybdenum oxide added was used. The sensitivity of this gas sensor represented by the rate of change of resistance in air and 500 ppm of hydrogen is about 20, and the sensitivity represented by the rate of change of resistance in air and 500 ppm of ammonia is about 10. And the ratio of ammonia sensitivity to hydrogen sensitivity was about 0.5.

In the comparative example, as the gas sensor S, a catalyst-sensitized semiconductor gas sensor mounted on a commercially available air cleaner [manufactured by Figaro Giken Co., Ltd., trade name: TGS 80
0] was used. In addition, in the air of this gas sensor and hydrogen 5
Sensitivity expressed by the rate of change of resistance value in the atmosphere of 00ppm is 1
The sensitivity represented by the rate of change of the resistance value in the air was about 5 and the sensitivity represented by the rate of change of the resistance value in the atmosphere of 500 ppm of ammonia was only about 3, and the ratio of the ammonia sensitivity to the hydrogen sensitivity was about 0.2.

According to the time-output voltage characteristic diagram shown in FIG. 2, the output of the gas sensor is increased with the combustion of the cigarette in both the present embodiment (1) and the comparative example (2), and almost no change occurs. Can't be seen. However, when the cigarette burns and the air cleaner operates, the output of this example (1) decreases with time, whereas the output of the comparative example (2) decreases by 30.
The output hardly decreased even after a lapse of minutes. Although not shown, the output voltage Vout is assumed to be sampled at regular intervals.

Next, an example of the control operation of the air cleaner using the output voltage Vout of the gas sensor detected by the detection circuit shown in FIG. 1 will be described with reference to FIGS. 3 and 4.
FIG. 3 is a control flowchart showing an example of the control operation of the air cleaner. FIG. 4A is a graph showing the change in the value of the output voltage Vout when the concentration of cigarette smoke is changed so that it can be confirmed that the flowchart shown in FIG. 3 all works. FIG. 4B is an operation diagram showing an operation change of the fan of the air cleaner controlled by the flowchart of FIG. 3 in accordance with the change of FIG. 4A.

Here, VL, VM and VH in the figure are predetermined starting values corresponding to the operation modes "weak", "medium" and "strong" of the fan of the air cleaner, respectively, and are based on the reference voltage M. It is a value set within the output range of the output voltage Vout. It is preferable that the predetermined value for starting is set with equal difference or equal ratio. Further, the coefficients a, b, and c in the figure are values obtained from experience of 1 or less, and are set to predetermined stop values by making them coefficients of predetermined start values.

First, the minimum value of the output voltage Vout in a predetermined period is stored as the reference voltage M, and the output voltages Vout and eM are stored.
(E is a coefficient obtained from experience) is used to judge the contamination detection. When the output voltage Vout is higher than eM, it is detected as contamination, and the output voltage Vout is compared with the predetermined starting value VL. In other cases, the loop is turned again.
When the output voltage Vout is larger than the predetermined value VL for starting, the air cleaner is operated "weakly", otherwise the loop is turned again.

During the "weak" driving operation, the output voltage Vout
And the previous output voltage V'out (2 seconds before), the output voltage Vou
When t is smaller than the previous output voltage V'out, it is determined that the output of the gas sensor has started to decrease, and the timer is started from that point, otherwise the timer is reset. After that, both output voltage Vout and predetermined start value V
When the output voltage Vout is larger than the predetermined value VM, the air cleaner is operated "medium". Otherwise, the output voltage Vout and the predetermined stop value aVL
The output voltage Vout is compared with the predetermined value for stop aV.
If it is smaller than L, turn off the air cleaner fan and return to the start.In other cases, determine whether the timer has passed the specified time, and if it is, turn off the air cleaner fan as well. Then, the process returns to the start, and in other cases, the process returns to the comparison between the output voltage Vout and the previous output voltage V'out (2 seconds before). Hereinafter, the operation switching control of the air cleaner is performed by the same process during the "medium" driving operation and the "strong" driving operation.

In the above operation test, normally, when the output voltage Vout reaches the predetermined stop value aVL, the fan is controlled as shown by the dotted line in FIG. 4B.
In order to confirm the operation of the forced stop means, the output voltage Vout
Has shortened the set time of the timer of the forced stop means that operates from the point when the value reaches bVM. As a result, as shown by the solid line in FIG. 4B, the output voltage Vout is the predetermined stop value aV.
It was confirmed that the fan was turned off because the set time of the timer had passed before reaching L, and the air cleaner was stopped by the forced stop means.

In the above embodiment, the gas sensor used was a tin oxide thin film as a gas sensitive material, but a tin oxide sintered body was used as a gas sensitive material, or an indium oxide thin film or an indium oxide sintered body was used. May be a gas sensitive body. In addition, at the time of starting and stopping, a delay may be provided to prevent chattering of the fan.

[0027]

As described above in detail, according to the present invention, by using the gas sensor having high sensitivity to the gas that can be purified by the air cleaner, it is possible to accurately reduce the output of the gas sensor as the air is purified. Since it is a control that stops the air cleaner when the output of the gas sensor becomes less than the predetermined value for stop, it can handle the change with time of the filter of the air cleaner, and it has human olfactory characteristics. Reasonable control became possible. By any chance,
When the output of the gas sensor has not dropped to the predetermined stop value, the air cleaner can be forcibly stopped. Furthermore, when the fan operation mode of the air cleaner is set in stages, the air cleaner can be gradually switched to the operation mode according to the output of the gas sensor and stopped, so that it can be stopped depending on how dirty the air is. Efficient operation control is possible.

[Brief description of the drawings]

FIG. 1 is a detection circuit diagram of a method for controlling an air cleaner according to this embodiment.

FIG. 2 is a time-output voltage characteristic diagram of gas sensors in the present example and the comparative example.

FIG. 3 is a control flowchart showing an example of a control operation of the air cleaner according to the present embodiment.

FIG. 4 is a view for confirming that all the flowcharts shown in FIG. 3 work, and FIG. 4A shows a change in the value of the output voltage Vout when the concentration of cigarette smoke is changed. The graph and (b) are operation diagrams showing the operation change of the fan of the air cleaner controlled in accordance with the change of (a).

FIG. 5 is a control flowchart of a conventional air cleaner control method.

[Explanation of symbols]

 S ... Gas sensor Rs ... Gas sensor resistance H ... Heater Vc ... Circuit voltage Vr ... Load resistance Vout ... Output voltage

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Claims (2)

[Claims] 1. A method of controlling an air cleaner that controls start and stop of an air cleaner based on the output of a gas sensor having a high sensitivity to a gas that can be purified by an air cleaner. A method for controlling an air cleaner comprising: a starting means for starting the cleaner; and a stopping means for stopping the air cleaner when the output of the gas sensor begins to decrease and the output of the gas sensor becomes a predetermined value for stop or less. . 2. The control method for an air cleaner according to claim 1, wherein only when the stop means does not operate even though the output of the gas sensor is starting to decrease.
A method for controlling an air cleaner, comprising a forced stop means for forcibly stopping the air cleaner by a timer operated immediately after the output of the gas sensor starts to decrease.