JPH02126084A - Controlling method for deodorizing of refrigerator - Google Patents

Abstract

PURPOSE:To facilitate the control of deodorizing and to detect a decrease in the freshness of food in a refrigerator by obtaining the degree of offensive odor in such a manner that odor concentration is low when a decrease in the output of a gas sensor is large upon operation of an deodorizer, and it is high when the decrease is, on the contrary, small. CONSTITUTION:A deodorizer 18 is operated for a period t2 of time of approx. 10 min-1 hour, and the reduction rate X of the output of a sensor 2 during this period is obtained. The rate X of the output of the sensor 2 due to the operation of the deodorizer 18 represents the degree of offensive odor, the larger the X is, the lower the odor concentration, and vice versa. When the rate X of the output of the sensor due to the offensive odor becomes an allowable value alpha or less, it is observed that the freshness of food in a refrigerator is lowered, it is displayed by a light emitting diode 24 to display the process of the food before it is putrefied.

Description

[Detailed description of the invention] [Field of application of the invention 1 The present invention relates to deodorization control for refrigerators.

[Prior Art 10] It is known to deodorize a refrigerator using a deodorizer using a generator or the like. In this case, the deodorizer uses a ceramic discharge plate or the like to generate O3 and eliminate odor substances to 0.
A substance that is removed by reacting with is used. As is well known, Ol is a toxic substance, and excess O3 is decomposed by the O3 decomposition catalyst and is not released outside the deodorizer. That is, in this deodorizer, air is sucked in with a fan and the air is 0. After deodorizing by reacting with O2, excess Ol is decomposed by a catalyst and discharged.

The problem with controlling a deodorizer with a gas sensor is that the sensitivity of the sensor to odors is low, and the sensor output is buried in external factors such as fluctuations in ambient temperature and humidity and changes in the sensor over time. Furthermore, since odor generation generally progresses slowly over a long period of time, an increase in sensor output due to odor cannot be interpreted as a sharp peak-like change in sensor output, which also makes detection difficult. In the field of air conditioning control using gas sensors, a system is known that detects air contamination based on a sharp increase in the output of a gas sensor and performs ventilation (Japanese Patent Publication No. 59-39.330). However, in the case of deodorization control, since odor generation is slow, a signal such as a sharp increase in sensor output corresponding to odor generation cannot be obtained.

In addition to these problems, it would be convenient if the deterioration in freshness of food stored in the refrigerator could be detected from the smell and the deterioration in freshness could be displayed.

[Problems to be solved by the invention] The problems to be solved by this invention are as follows: (1) To obtain a new odor detection method using a gas sensor to facilitate deodorization control; (2) To detect a decrease in the freshness of food in a refrigerator. There is a thing.

[Terminology 1] In this specification, the output of a gas sensor is shown as increasing as the odor increases and decreasing as the odor decreases. However, this is a relative concept in signal processing and is just a nomenclature convention. For example, if the electrical conductivity of a gas sensor increases due to odor, the resistance value of the sensor decreases due to odor.

The present invention does not exclude outputting the resistance value instead of the electrical conductivity in such a case.

[Structure of the Invention] The deodorization control method for a refrigerator of the present invention is a method in which odor is detected by a gas sensor and a deodorizer is controlled, and the degree of decrease in the gas sensor output accompanying the operation of the deodorizer is detected, The degree of odor is determined by assuming that the odor concentration is low when the decrease in the gas sensor output is large and that the odor concentration is high when the decrease in the gas sensor output is small, and the deodorizer is controlled according to the determined degree of odor. It is characterized in that when the decrease in the output of the gas sensor during operation is below a permissible value, a decrease in the freshness of the food in the refrigerator is displayed.

The inventor discovered the following phenomenon. When a deodorizer is installed and operated at an appropriate position in a refrigerator, the sensor output decreases significantly when there is no odor source, and the decrease in sensor output is small when there is an odor source. That is, the decrease in the sensor output due to the operation of the deodorizer is related to the degree of odor, and the higher the odor concentration, the smaller the decrease in the sensor output.

The inventor estimated the cause of this as follows. Even when there is no particular source of odor, the air contains trace amounts of malodorous substances such as hydrogen sulfide and ammonia, and flammable gases such as cobalt and methane. In addition to this, it also contains rubber, solvent, and other vapors generated from refrigerator packages and the like. Gas sensors are also sensitive to these things. When the deodorizer is operated at this point, these gases are removed and the sensor output is significantly reduced. If a source of bad odor is present, operating the deodorizer will not completely eliminate the odor. Depending on the balance between the rate of generation of odorous substances and the rate of deodorization by the deodorizer, the odor concentration will only decrease up to a value of j; This I: The reduction ratio of the odor concentration is small, and the gas sensor output does not decrease much.

By using this phenomenon in reverse, it becomes possible to detect the degree of odor from the degree of decrease in sensor output accompanying the operation of the deodorizer.

Next, if the decrease in the sensor output due to the operation of the deodorizer is extremely small, that is, if the decrease in the sensor output is below a permissible value, the odor concentration in the refrigerator will be extremely high. This means that the freshness of the food in the refrigerator has decreased and a high concentration of odor is generated. Therefore, if the decrease in the sensor output due to the deodorizer operation is below the allowable value, an indication of the decrease in food freshness is displayed.
We urge people to use food before it spoils.

[Example] FIG. 1 shows a circuit diagram of the device. In the figure, O1 is a commercial power supply, 02 is a DCC constant voltage power source 03 is a thermistor for detecting the internal temperature, o4 is its load resistance, and 05 is a microcomputer for controlling the refrigerator. Further, 06 is a group of control switches for quick freezing, internal temperature setting, etc. 07 is a cooling compressor, and 08 is its switch.

2 is a gas sensor, which is installed at an appropriate position inside the refrigerator.

As the gas sensor 2, for example, a gas sensor for detecting an odor using a change in the resistance value of SnO is used. 4 is a load resistance of the gas sensor 2. Make the value of load resistor 4 sufficiently small,
The voltage applied to the load resistor 4 is set as the gas sensor output so that an output corresponding to the electrical conductivity of the gas sensor 2 appears. As the output of the gas sensor 2, any other output such as its resistance value may be used.

6 is a microcomputer, for example, an A/D converter 8, an arithmetic and logic unit 101, which stores various variables; RAM 12, a clock generation circuit 14, and a timer 16;
It consists of 18 is 0. 20 is a switch for a deodorizer using an ultraviolet generator or an ultraviolet generator. Further, 22 is a switch such as a transistor, and 24 is a light emitting diode for indicating the deterioration of food freshness. Light emitting diode 2 is used to indicate the decrease in freshness.
Any number other than 4 may be used.

Table 1 shows the types of variables used in the examples.

Table 1 Variable Cold View ΔT Vc Vm ■1 std t r# t 3 Meaning Inner temperature, gas sensor output of the difference between the inward temperature detected by thermistor 03 and the standard temperature, output of load resistor 4 Compensated by inward temperature Sensor output when deodorizer starts operation Sensor output reference output Sensor output when deodorizer stops Sensor output reduction rate due to deodorizer operation Deodorizer operation start threshold Operate the deodorizer with the deodorizer control signal F-1, The deodorizer is stopped at 0, the freshness drop display signal is turned on, and the light emitting diode 24 is turned on at J-1, and the light emitting diode 24 is turned off at J-0.Tolerance value for detecting the drop in freshnessThe operating time of the timer 16The operation of the embodiment is shown in FIG. This will be explained using a flowchart. As shown in FIG. 4, the raw gas sensor output V varies by about 10% depending on whether the compressor 07 is turned on or off. This is due to fluctuations in the temperature inside the refrigerator due to the operation of the compressor 07. Therefore, a subroutine for obtaining the compensated gas sensor output Vc is provided, and signal processing is performed using the output Vc after temperature compensation. In this subroutine, the A/D converter 8 is used to read the output of the thermistor 03, and the internal temperature T is determined. The difference between the internal temperature T and the standard temperature is ΔT, and from this value, Vc is obtained, for example, as Vc=VA·ΔT (A is the temperature coefficient of the gas sensor).

Various other methods are possible for calculating Vc. Since the fluctuation of the sensor output ■ is synchronized with the operation of the compressor 07, it is sufficient to obtain a signal related to the operation of the compressor 07 from the Myra Taro computer 05 and sample the sensor output Vc in synchronization with the operation of the compressor 07. . Alternatively, the sensor output may be sampled over a period of time longer than the operating cycle of the compressor 07 (usually about 20 minutes) and averaged to obtain Vc. Of course, if there is sufficient margin for odor detection accuracy, the compressor 07 may be left with noise accompanying its operation.

Returning to FIG. 2, when the device starts operating, the reference output V0 is set to a sufficiently large constant as initialization. Next, the process moves to subroutine G for operating the deodorizer 18 and detecting odor.

In this subroutine, the deodorizer 18 is opened for a time t1 of about 10 minutes to 1 hour, and the reduction rate X of the sensor output during this period is determined.

Here, it is assumed to be X-Vm/Vc (Vm is the sensor output at the start of the deodorizer operation), but in subsequent detections, Vm is equal to the operation threshold Vstd, so there is no need to specifically find Vm.

The reduction rate X of the sensor output due to the operation of the deodorizer indicates the degree of odor. -For example, if you put a large amount of fresh food in the refrigerator and feel a slight odor, the relative value of the sensor output (1 air conductivity) will be 2 to 3 compared to the empty refrigerator.
About twice as much. Refrigerators are generally used for several years, so this output is insufficient if the sensor changes over time.

Next, when the deodorizer 18 starts operating, if a large amount of food has a slight odor, X becomes about 1.7 after 30 minutes and about 2 after 1 hour. Note that this is the case when a large amount of fresh food is stored in the refrigerator.

On the other hand, in an empty refrigerator, X will be around 3 after 30 minutes and around 6 after 1 hour. Furthermore, if a large amount of old food has a strong odor, the value of X will be about 1.3 30 minutes after the start of deodorization and about 1.5 after 1 hour. Extend the shelf life of food,
When a stronger odor is generated, the value of X becomes approximately 1°1 to 1.2 30 minutes after the start of deodorization, and approximately 1.3 after 1 hour. Therefore, it can be seen that the larger X is, the lower the odor concentration is, and the smaller X is, the higher the odor concentration is. Further, when the rate of decrease in sensor output due to deodorization X becomes less than the allowable value α, it can be seen that the freshness of the food in the refrigerator has decreased. So X
is less than α, a decrease in freshness is detected and marked as J-1, which is displayed by the light emitting diode 24 to indicate that the food should be disposed of before it spoils.

Another advantage of using the reduction rate X of the sensor output due to deodorization is that the influence of external factors such as temporal fluctuations in the sensor output and fluctuations in ambient temperature and humidity is small. That is, even if the sensor output shifts due to these influences, the value of X itself is not directly affected by these influences. The reason why X is defined as the reduction rate here is to normalize with the original output Vm. Instead of the ratio, the difference between the original output and the output after deodorization may be used.

Since the degree of odor is determined by X, the time t for additional deodorization is determined as a decreasing function of X. This deodorizing operation means deodorizing processing according to the degree of detected odor. For example, if the relationship between
The upper limit is set to about 3 hours, for example. The sensor output Vc at the time when time t2 has elapsed is set to Vl, and vl and V are compared. ■If 1 is below V, the odor concentration has decreased below the level corresponding to the previous reference value Vo, so V
1 is substituted for vo, and the deodorizer 18 is stopped.

At the same time, the next deodorization trigger level Vs t df, V
std-V, +B-X (B: constant), etc., and deodorization is thereafter performed when Vc exceeds Vstd.

This is the allowable range of sensor output until the next deodorization.
(B is a positive constant), and is equivalent to setting a large tolerance range when the odor is low, and a small tolerance range when the odor is high. When X is less than or equal to σ, the value of B-X becomes extremely small, so if the sensor output Vc increases even slightly from V, the next deodorization will start. Note that the determination of Vstd is not limited to the above-mentioned method, and any method that determines the allowable width B-X as an increasing function of X may be used.

T! If the sensor output v1 after the elapsed time exceeds V, lO
Additional deodorization is performed for a time period of about 1 minute to 1 hour, with an upper limit of 1 s, and if Vc drops below V during this time, the deodorizer 18 is stopped. In this case, the output V1 at the time when the deodorizer 18 stops is set as the new Vo. On the other hand, if the output does not fall below V0 even after time t has elapsed, deodorization]8 is stopped after time t3 has elapsed, and the output VI at that point is
Let be the reference output V. However, in the case of J-1 (when displaying a decrease in freshness), the previous reference output V is maintained as it is. These steps are for confirming whether or not the reason why Vc does not fall below V is due to insufficient deodorization. Therefore, if the output decreases during the allowable time t3, it is assumed that this is due to insufficient deodorization. On the other hand, if the output does not fall below V0 during t3, Vl is accepted as the new reference output V, assuming that this is due to external factors such as changes in temperature and humidity. Note that when a decrease in the freshness of the food is detected in J-1, the reason why the output does not decrease is because an odor exceeding the capacity of the deodorizer 18 has occurred, and the previous reference output V0 is maintained.

After that, these loops are repeated until the sensor output reaches the threshold value Vs.
Deodorization is started when td is exceeded, and the degree of odor is determined from the rate of decrease in sensor output accompanying deodorization, and the deodorizer 18 is controlled. Furthermore, the value of X may be compared with α, and when X is less than or equal to α, a display of reduced freshness is performed, and when X is greater than α, the display of reduced freshness is turned off.

The operation of the embodiment is shown in FIG. The solid line in the figure shows the standard odor state, and the broken line shows the odorless state. If there is an odor, the output reduction rate X due to the operation of the deodorizer 18
is small, and when there is no odor, X is large. Therefore, the additional deodorization time t2 is determined by X. Further, as shown by the chain line on the right side of the figure, when the rate of decrease in the sensor output when the deodorizer 18 is operated is less than or equal to α, the light emitting diode 24 indicates that the freshness of the food in the refrigerator has decreased.

Although the value of α was set to 1.2 in the embodiment, it may be changed as appropriate depending on the type of sensor, the capacity of the deodorizer 18, etc.

In the embodiments, specific things have been explained along with specific numerical conditions, but the present invention is not limited to this. For example, in the embodiment, the degree of odor is measured each time deodorization is performed, but the degree of odor is measured once per day, and in other cases, the degree of odor is measured by simply operating the deodorizer 18. may be omitted. In this case, the operating duty ratio of the deodorizer 18 from now on is determined by measuring the odor, and the deodorizer 18 is driven at this duty ratio for about one day thereafter.

[Effects of the Invention] In the present invention, the degree of odor is detected from the degree of decrease in the gas sensor output accompanying the operation of the deodorizer, and deodorization is controlled.

That is, the odor concentration is determined to be low when the decrease in output is large, and the odor concentration is determined to be high when the decrease in output is small. This detection method provides a high output that corresponds to the degree of odor, and also provides a highly reliable signal that is independent of fluctuations in ambient temperature and humidity, changes in the sensor over time, and the like. Furthermore, in this invention, a decrease in freshness of food in the refrigerator is displayed to eliminate food waste.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of the embodiment, FIG. 2 is an operation flowchart thereof, and FIGS. 3 and 4 are operational characteristic diagrams of the embodiment. In the figure, 03 07 compressor, 2 6 microcomputer, 18 deodorizer, 24 thermistor, gas sensor, light emitting diode.

Claims (1)

[Claims] (1) In a method in which odor is detected by a gas sensor and the deodorizer installed in the refrigerator is controlled, the degree of decrease in the gas sensor output due to the operation of the deodorizer is detected, and when the decrease in the gas sensor output is large, the odor is detected. The degree of odor is determined by assuming that the odor concentration is low and the odor concentration is high when the decrease in gas sensor output is small, and the deodorizer is controlled according to the determined degree of odor. A method for controlling deodorization of a refrigerator, characterized by displaying a decrease in freshness of food when the decrease is below an allowable value.