JPH0526416Y2 - - Google Patents

Description

[Detailed description of the invention] [Terminology] In this specification, an increase in gas sensor output refers to a change in sensor output corresponding to the progress of air pollution, and a decrease or reduction in sensor output refers to a change in sensor output corresponding to the progress of air pollution. Indicates the change in sensor output on the side that corresponds to purification.

[Field of application of the invention] This invention relates to control of an air cleaner using a gas sensor.

[Prior art] JP-A No. 60-27849 proposes that the minimum value of the gas sensor output during a predetermined sampling period is used as a reference output corresponding to clean air, and that atmospheric contamination is detected by comparing with this output. are doing. In this way, it is possible to avoid the influence of daily fluctuations in the sensor or fluctuations in the sensor output unrelated to air pollution due to temperature and humidity. Further, there is no need to adjust the gas sensitivity of each individual sensor.

However, if the ambient temperature and humidity increase extremely rapidly, even if the air cleaner is operated, the output of the gas sensor will not decrease, making it difficult to control the air cleaner to stop. Furthermore, most air purifiers are intended to remove dust caused by smoking, etc., and have a low ability to remove gas. When smoking, gases such as hydrogen and carbon monoxide are generated along with dust, so if these gases are detected, smoking can be detected and the air purifier can be operated. However, even if an air purifier is operated to remove dust, if the gas removal ability is low, the gas concentration will not decrease much. Therefore, even after dust removal is completed, the gas sensor output may not decrease. In such a case, it becomes difficult to stop the air cleaner appropriately.

[Problem of the invention] The object of this invention is to perform appropriate stop control for air conditioning equipment.

[Configuration of the invention] The air purifier control device of this invention includes a gas sensor for detecting atmospheric pollution, a storage means for storing the minimum value of the gas sensor output in a predetermined period as a reference output, A starting means is provided for detecting that the gas sensor output has increased by a predetermined value or more with respect to the reference output and operating the air cleaner.

Here, the air purifier control device of this invention includes a saturation detection means for detecting that the change width of the gas sensor output is less than a predetermined value while the air purifier is operating; , an output drop detection means for detecting a drop in the gas sensor output is provided, and the air cleaner is configured to be stopped at the output of either the saturation detection means or the output drop detection means. .

Here, the predetermined period may be, for example, about 10 minutes to 30 minutes, and the minimum value of the sensor output during this period may be used as the reference output. In the detection of saturation, it is detected that the variation width of the gas sensor output is less than a predetermined value and there is no substantial increase in the gas concentration during operation of the air purifier. The output decrease detection means literally decreases the gas sensor output during operation of the air purifier, and detects that the gas concentration in the atmosphere has decreased. An example using a microcomputer will be described below, but the invention is not limited to this, and appropriate changes can be made within the range of known techniques.

[Example] Fig. 1 shows the hardware of the apparatus. In the figure, 2 is an AC power source, 4 is a transformer, and 6 is a gas sensor, in which a heater electrode 10 and another electrode 12 are embedded in a metal oxide semiconductor 8 such as SnO ₂ . Here, if the electrical conductivity of the gas sensor 6 is taken as the output, the gas sensor output increases with air pollution. However, the subsequent microcomputer 24 performs signal processing using the resistance value of the gas sensor instead of the electrical conductivity. The resistance value of the gas sensor 6 is the reciprocal of the output and decreases due to air pollution.

14 is a load resistor, 16 is a diode for half-wave rectification, 18 is a resistor, and 20 is a capacitor, which smooths and extracts the gas sensor output. Further, from the transformer 4, an unstable DC power source A and a stabilized DC power source B are taken out.

22 is a comparison circuit, 24 is a microcomputer for control, and 26 is a capacitor. Reference numeral 28 denotes a sensitivity changeover switch, which is used by the user to input a sensitivity setting index K into the microcomputer 24. The switch 28 is provided with, for example, a high-sensitivity switch and a low-speed switch for selection, and the input signal is input to the microcomputer 24 from the I3 terminal. When switch 28 is selected to the high sensitivity side,
The air purifier will operate even if the gas sensor output increases slightly, and if the low sensitivity side is selected, the air purifier will not operate unless there is a large increase in the sensor output.

The I2 input of the microcomputer 24 is periodically grounded via the reset contact R _e so that the charge on the capacitor 26 is periodically discharged. After finishing discharging, charging to the capacitor 26 is started,
The time required for the potential of the capacitor 26 to reach the comparison potential of the comparison circuit 22 is counted. Since the charging current to the capacitor 26 is proportional to the gas sensor output, this time is proportional to the resistance value of the gas sensor 6. Note that I1 is an input terminal for inputting changes in the output signal of the comparison circuit 22 to the microcomputer 24.

30 is an interface with the air purifier, 32
is a group of light emitting diodes for display purposes, such as light emitting diode LED1 for standby display, light emitting diode LED2 for cleaning display, and light emitting diode for contamination display.
It is made up of LED3. 34 is an air purifier,
It has three operation modes: rapid operation H, medium operation M, and weak operation L. The air cleaner 34 collects dust by charging dust in the air, and has a high ability to remove dust, but a low ability to remove gas. Therefore, if the air cleaner 34 is operated without ventilation, such as after smoking, the gas sensor output remains constant and hardly decreases.

FIG. 2 shows a block configuration centered on the microcomputer 24. For example, the resistance value of the gas sensor 6 is changed to A/2 every 2 seconds using the comparison circuit 22.
D-convert it and store it in memory as sensor resistance Rs.
Then, the maximum value of the sensor resistance Rs during a predetermined period of about 20 minutes is set as a reference value M and stored in memory. The sensor resistance Rs increases as the air becomes cleaner, and decreases as the air becomes more polluted. Therefore, the sensor resistance over a given period of time
By storing the maximum value M of Rs, the sensor resistance to clean air can be stored. However, since it is meaningless to store too old data due to changes in temperature and humidity, etc., here, 20 minutes is set as the period of the predetermined value, and the maximum value of the sensor resistance during 20 minutes is set as the reference value M.

The sensitivity setting index K is for modifying the operating conditions of the air purifier 34 according to the user's preference.
Input from switch 28. As will be described later, the air cleaner 34 is operated according to the value of Rs/(M·K), and a decrease in this value below 1 is a sign of air pollution. Therefore, if K is increased, even if the change in sensor resistance Rs is small, the air purifier 34
operates, and if K is decreased, the air cleaner 34 will not operate unless the sensor resistance Rs changes significantly.

The microcomputer 24 is provided with a starting means for detecting atmospheric contamination and starting the air cleaner 34. In the starting means, the sensor resistance value
Using Rs, reference value M and sensitivity setting index K,
Contamination in the atmosphere is detected and the value of Rs/(M·K) is compared with a threshold value to detect contamination. When the atmosphere becomes polluted, the sensor resistance Rs decreases, so the value of Rs/(M·K) also decreases. This is equivalent to detecting a decrease in the sensor resistance Rs with respect to the reference value M and correcting it to the sensitivity setting index K. Note that when the air cleaner 34 is operated, the light emitting diode LED3 for indicating pollution is turned on, and when the operation is finished, the light emitting diode LED2 for indicating cleanliness is turned on.

Three types of threshold values are provided for Rs/(M·K), and are made to correspond to three types of operation modes: weak operation L, medium operation M, and rapid operation H. For example, if the threshold for weak operation L is 0.7, the threshold for medium operation M is 0.6, and the threshold for rapid operation H is 0.5, then when Rs/(M・K) becomes smaller than these thresholds, The air cleaner 34 is operated in the corresponding operation mode.

Further, the microcomputer 24 is provided with means for detecting saturation of the gas sensor output. In the detection of saturation, it is detected that no new gas is generated after the air cleaner 34 starts operating. The saturation detection means samples the sensor resistance Rs at intervals of about 2 minutes to obtain the saturated output R1, and if the ratio of Rs/R1 is maintained within a predetermined range for 2 minutes thereafter, the sensor resistance Rs becomes saturated. Suppose we did. The air cleaner 34 may be stopped immediately upon detection of saturation, but here a timer is provided and the air cleaner 34 is operated in the same operating mode for about 20 minutes, for example. If the sensor output increases again while the timer is operating, the timer is reset and the operation mode is strengthened as necessary. Here, the timer reset condition is Rs/R1<0.7K. Note that R1 represents the saturated output and is the sensor resistance read every 2 minutes. This means that a change in sensor resistance of 30% or more per 2 minutes will reset the timer.

Further, the output resistance detection means detects a decrease in the sensor output and stops the operation of the air cleaner 34.
The output drop detection means includes a sensor resistance Rs, a reference value M,
Using the sensitivity setting index K, a decrease in the sensor output is detected from the value of Rs/(M·K). When the air is purified and the gas concentration decreases, the sensor resistance Rs increases, so a decrease in the gas sensor output is detected from an increase in this value. Note that the threshold value at the time of detecting a decrease in output and the threshold value at the time of starting the air cleaner 34 may be equal to each other, or may be different to prevent chattering or the like.

When the air purifier 34 stops operating, the reference value M
Update. That is, the sensor resistance Rs when the air cleaner 34 is stopped is set as a new reference value, and the reference value is corrected. If the old reference value is used as it is, if the air purifier 34 is stopped by the timer after saturation is detected, the sensor resistance Rs will remain low, so Rs/
This is because the value of (M·K) is small and the air cleaner 34 will operate again.

The operation of the apparatus will be explained with reference to FIGS. 3 and 4. When the power is turned on, the light emitting diode LED1 is turned on for 2 minutes until the gas sensor 6 stabilizes to display a standby state. Thereafter, the sensor resistance Rs is read and that value is set as the initial value of the reference value M. Next, the sensor resistance Rs is compared with the reference value M, and if the sensor resistance Rs is greater than or equal to the reference value M, the reference value M is
Update. The point at which the reference value M is updated is shown as point Q in FIG. The reference value M is the maximum value of the sensor resistance during a predetermined period, here the past 20 minutes. Therefore, the maximum value of the sensor resistance is sampled for each period, and the reference value M is corrected at the turn of the period.

A case where the sensor resistance Rs decreases to 0.7 M·K or less (0.7 is a constant determined empirically) is considered to be a contaminated state. When pollution is detected, the light emitting diode display changes from light emitting diode LED2 to light emitting diode LED3.
and start the air purifier 34. The operation mode of the air cleaner 34 is, for example, weak operation when 0.6<Rs/M·K<0.7, medium operation when 0.5<Rs/M·K<0.6, and rapid operation when Rs/M·K<0.5.

After the air purifier 34 starts operating, for a predetermined period of time, for example, 2
After 2 minutes have elapsed, the saturated output R1 is sampled, and if the state of Rs/R1≧0.95 continues for 2 minutes, it is considered saturated. At the time of saturation, for example, a 20 minute timer is started, and the air cleaner 34 continues to operate during this time. If the sensor resistance Rs decreases during this time, for example, if Rs/R1<0.7K, the timer is reset, saturation detection is disabled, and the operation mode is changed according to the above-mentioned criteria.

To prevent chattering, etc., strengthening the driving mode, for example, changing from low to medium driving, is done immediately, but lowering the driving mode, for example, changing from medium to weak driving, takes about 1 minute. Do this after the period has elapsed. Even if the sensor output drops below the weak operation level, the operation will be stopped after one minute has elapsed.

FIG. 4 shows the detection of saturation and the subsequent operation of the timer. The solid line sensor output in FIG. 4a is an example where the air cleaner 34 is stopped by detection of saturation and the subsequent timer, and the broken line is an example where the air cleaner 34 is stopped by a signal from the output drop detection means. . FIG. 4b shows the operation of the air cleaner 34 due to the detection of saturation, and FIG. 4c shows the operation of the air cleaner 34 due to the detection of a decrease in output. Also, Q in Figure 4a is the standard value M
, the start signal of the timer of the saturation detection means is S, and the end signal thereof is Soff.

The solid line in FIG. 4a shows that the timer operates once after the start of medium operation, and then is reset due to an increase in the sensor output. Then, a timer is started after switching to rapid operation, and operation is stopped after the timer turns off. Accordingly, the display of the light emitting diode is changed and the sensor resistance when the timer is off is memorized as the reference value M. The sensor resistance at this point means the sensor resistance after the air has been processed within the capacity of the air purifier 34. If the reference value M is not updated here, the air cleaner 34 will not stop.

Next, when the sensor output gradually decreases as shown by the broken line in FIG. The operation is stopped by the signal from the drop detection means. Furthermore, the sensor resistance at this point is updated as the reference value M.

In the embodiment, the ratio between the sensor resistance Rs and the reference value M is used, but a difference may be used instead of the ratio.

[Effects of the invention] This invention detects the saturation of the gas sensor output while the air purifier is operating, confirms that there is no increase in gas concentration, and confirms that there are no new sources of gas such as smoking. do. In this invention, the air cleaner is stopped when the gas sensor output is saturated or the gas sensor output decreases while the air cleaner is in operation. Therefore, the air cleaner can be stopped not only when gas is actually removed, but also when the gas sensor output is saturated and no new gas is generated.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of the control device of the air purifier according to the embodiment, Fig. 2 is a block diagram of the embodiment, Fig. 3 is its control flowchart, and Figs. 4 a, b, and c show its operating characteristics. FIG.

Claims (1)

[Scope of claim for utility model registration] A gas sensor for detecting atmospheric pollution;
A storage means for storing the minimum value of the gas sensor output in a predetermined period as a reference output; and an activation device for operating the air purifier upon detecting that the gas sensor output has increased by more than a predetermined value with respect to the reference output. a saturation detection means for detecting that the range of change in the output of the gas sensor is less than or equal to a predetermined value while the air cleaner is operating; , an output drop detection means for detecting a drop in the output of the gas sensor is provided, and the air cleaner is configured to be stopped at the output of either the saturation detection means or the output drop detection means. , air purifier control device.