JP2620964B2 - Refrigerator deodorization control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to deodorization control of a refrigerator.

[Related Art] It is known that a refrigerator is deodorized by a deodorizer using an O ₃ generator or the like. As the deodorizer in this case, one that generates O ₃ by a ceramic discharge plate or the like and reacts and removes odorous substances with O ₃ is used. As is well known, O ₃ is a toxic substance, and excess O ₃ is decomposed by an O ₃ decomposition catalyst and is not released outside the deodorizer. That is, in this deodorizer, air is sucked by a fan, reacted with O ₃ and deodorized, and then excess O ₃ is decomposed by a catalyst and discharged.

The problem with controlling the deodorizer with a gas sensor is that the sensitivity of the sensor to odor is low,
The sensor output is buried in an external factor such as a change with time of the sensor. Further, since the generation of odor is generally a phenomenon that progresses slowly over a long period of time, it is difficult to detect the increase in sensor output due to the odor as a sharp change in the sensor output, which makes detection difficult. In the field of air-conditioning control using a gas sensor, there is known a method of detecting air pollution from a sharp increase in the output of a gas sensor and performing ventilation (Japanese Patent Publication No. 59-39,330). However, in the case of the deodorization control, since the generation of the odor is slow, a signal such as a sharp increase in the sensor output corresponding to the generation of the odor cannot be obtained.

In addition to these problems, it is convenient if the decrease in freshness of the food stored in the refrigerator can be detected from the smell so that the decrease in freshness can be displayed.

[Problems of the Invention] An object of the present invention is to (1) obtain a new odor detection method using a gas sensor to facilitate deodorization control, and (2) detect a decrease in freshness of food in a refrigerator. That is,

[Terminology] In this specification, the output of the gas sensor is shown to increase as the odor increases and decrease as the odor decreases.
However, this is a relative concept in signal processing and is merely a terminology promise. For example, when the electric conductivity of the gas sensor increases due to odor, the resistance value of the sensor decreases due to odor. The present invention does not exclude the case where the resistance value is output in place of the electric conductivity in such a case.

[Constitution of the Invention] The method for controlling the deodorization of a refrigerator according to the present invention is a method for controlling the deodorizer by detecting an odor with a gas sensor and detecting a degree of decrease in the output of the gas sensor accompanying the operation of the deodorizer, The odor concentration is assumed to be low when the output of the gas sensor is large and the odor concentration is assumed to be high when the output of the gas sensor is small.The deodorizer is controlled according to the obtained odor, and the deodorizer is controlled. When the decrease in the output of the gas sensor during operation is equal to or less than the allowable value, a display indicating a decrease in the freshness of the food in the refrigerator is performed.

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

The inventors presumed the cause 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 combustible gases such as CO and methane. In addition, it contains steam such as rubber and solvent generated from the refrigerator package and the like. Gas sensors are also sensitive to these. Operating the deodorizer now removes these gases and significantly reduces the sensor output. If there is a source of offensive odor, operating the deodorizer does not completely eliminate the odor. Only the odor concentration is reduced to a value corresponding to the balance between the generation rate of the odorous substance and the deodorization rate in the deodorizer. Therefore, the reduction ratio of the odor concentration is small, and the output of the gas sensor does not decrease so much.

By reversing this phenomenon, it is possible to detect the degree of odor from the degree of decrease in sensor output due to the operation of the deodorizer.

Next, when the decrease in the sensor output due to the operation of the deodorizer is extremely small, that is, when the decrease in the sensor output is equal to or less than the allowable 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 has been generated. Therefore, when the decrease in the sensor output due to the operation of the deodorizer is equal to or less than the allowable value, a display indicating a decrease in freshness of the food is displayed, and a call is made to use the food before the spoilage.

Embodiment FIG. 1 shows a circuit diagram of the apparatus. In the figure, 01 is a commercial power supply, 02 is a DC constant voltage power supply, 03 is a thermistor for detecting the internal temperature, 04 is its load resistance, and 05 is a microcomputer for controlling a refrigerator. Reference numeral 06 denotes a group of control switches for quick freezing and setting the temperature in the refrigerator. 07 is a compressor for cooling, and 08 is its switch.

Reference numeral 2 denotes a gas sensor provided at an appropriate position in the refrigerator. As the gas sensor 2, for example, a gas sensor for odor detection using a change in the resistance value of SnO ₂ is used. Reference numeral 4 denotes a load resistance of the gas sensor 2. The value of the load resistor 4 is made sufficiently small so that an output corresponding to the electric conductivity of the gas sensor 2 appears, and the voltage to the load resistor 4 is used as the gas sensor output. As the output of the gas sensor 2, any other value such as its resistance value can be used.

Reference numeral 6 denotes a microcomputer which comprises, for example, an A / D converter 8, an arithmetic and logic unit 10, a RAM 12 storing various variables, a clock generation circuit 14, and a timer 16. 1
8 deodorizer using O ₃ and UV generator, 20 is the switch. Reference numeral 22 denotes a switch such as a transistor, and reference numeral 24 denotes a light emitting diode for indicating a decrease in freshness of food. Any indication other than the light emitting diode 24 can be used to indicate the decrease in freshness.

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

The operation of the embodiment will be described with reference to the flowchart of FIG. As shown in FIG. 4, the raw gas sensor output V fluctuates by about 10% due to the ON / OFF of the compressor 07.
This is due to a change in the internal temperature due to the operation of the compressor 07. So compensated gas sensor output
A subroutine for obtaining Vc is provided, and signal processing is performed using the output Vc after temperature compensation. In this subroutine, A /
The output of the thermistor 03 is read using the D converter 8, and the internal temperature T is obtained. The difference between the internal temperature T and the standard temperature is defined as ΔT, and Vc is obtained from this value, for example, as Vc = VA-ΔT (A is the temperature coefficient of the gas sensor).

Various other calculations are possible for calculating Vc. Since the fluctuation of the sensor output V is synchronized with the operation of the compressor 07, a signal relating to the operation of the compressor 07 may be obtained from the micro computer 05, and the sensor output Vc may be sampled in synchronization with the operation of the compressor 07. In addition, the operation cycle of compressor 07 (usually 20
The output of the sensor may be sampled over a period of about (minutes) or more, and averaged to obtain Vc. Of course, if there is a sufficient margin in the detection accuracy of the odor, noise accompanying the operation may be left in the compressor 07.

Returning to FIG. 2, when the operation of the apparatus is started, the reference output V _{0 is set} to a sufficiently large constant K for initialization. Next, the operation proceeds to the operation of the deodorizer 18 and the odor detection subroutine G. In this subroutine, deodorizer 18 is operated for 10 minutes about 1 hour time t _1, determining the reduction rate X during this period of the sensor output. Here, it is assumed that X = Vm / Vc (Vm is the sensor output at the start of the deodorizer operation), but Vm is equal to the operation threshold value Vstd in the next and subsequent detections, and it is not particularly necessary to find Vm.

The rate of decrease X in sensor output due to the operation of the deodorizer indicates the degree of odor. For example, when a large amount of fresh food is put into a refrigerator and a slight odor is felt, the relative value of the sensor output (electrical conductivity) is 2 to 2 with respect to an empty refrigerator.
It is about three times. Since the refrigerator is generally used for several years, this output is not sufficient in view of the aging of the sensor.

Next, when the operation of the deodorizer 18 is started, when a large amount of food has a slight odor, X becomes about 1.7 after 30 minutes and about 2 after 1 hour. This is the case where a large amount of fresh food is stored in the refrigerator. On the other hand, in an empty refrigerator, X is about 3 after 30 minutes and about 6 after 1 hour. If a large amount of older food has a strong smell, the value of X is 1.30 minutes after the start of deodorization.
It will be around 1.5 after about 1 hour. If the preservation period of the food is further extended and a more intense odor is generated, the value of X becomes about 1.1 to 1.2 in 30 minutes after the start of deodorization, and about 1.3 in 1 hour. Thus, it can be seen that the larger the X, the lower the odor concentration and the smaller the X, the higher the odor concentration. When the rate of decrease X of the sensor output due to deodorization becomes equal to or less than the allowable value α, it can be seen that the freshness of the food in the refrigerator is reduced. So X
Is smaller than α, a decrease in freshness is detected, J = 1, and the light emitting diode 24 is displayed to indicate that the food should be disposed of before it becomes spoiled.

Another advantage of using the reduction rate X of the sensor output due to deodorization is that the influence of an external factor such as a change over time in the sensor output and a change in ambient temperature and humidity is small. That is, even if the output of the sensor shifts due to these effects, the value of X itself is not directly affected by those values. Here, X is set as the reduction rate in order to standardize 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, defining the time t ₂ of the additional deodorizing as a decreasing function of X. This deodorizing operation means a deodorizing process according to the detected odor level. This example, leave the table in which a relationship between X and t ₂ in the ROM or the like, may load the table. The lower limit of t _2, for example 0, the upper limit should be for example about 3 hours. The sensor output Vc at the point where time t ₂ has elapsed and V _1, compares the V ₁ and V _0. If V ₁ is a V ₀ below, since the odor concentration has dropped below the level corresponding to the previous reference value Vo, substituting V ₁ to V _0, to stop the deodorizer 18. At the same time the trigger level Vstd of the next _{deodorization, Vstd = V 0 + B ·} X: defined as (B constant) or the like, hereinafter Vc performs deodorization when exceeded Vstd. This means that the allowable range of sensor output until the next deodorization is B ·
X is defined as X (B is a positive constant), which is equivalent to placing a large allowable range when the odor is low, and a small allowable range when the odor is high. If X is less than alpha, the value of B · X so very small, the sensor output Vc is increased even slightly from V _0, so that the next deodorization begins. Note that the determination of Vstd is not limited to the above, and the allowable width BX
What is necessary is just to determine.

If the sensor output V ₁ of the after t ₂ has elapsed exceeds V _0, 10 minutes to 1
To add deodorizing of time t ₃ about the time the upper limit, stopping the deodorizer 18 and Vc drops to V ₀ below during this period. In this case also, deodorizer 18 is an output V ₁ new V ₀ which at the stop time. If on the other hand the output with time t ₃ does not drop V ₀ below, the deodorizer 18 is stopped over time t _3, the output V ₁ of the at that time and the reference output V _0. Where J
= 1, the maintaining (If the product has been reduced display of freshness), as it is the last reference output V _0. These steps cause Vc is not lowered to V ₀ below it is used to check whether there lack of deodorization. So if the output during the allowable time t ₃ is decreased, handling and due to lack of deodorization. On the other hand, if the output does not drop below V ₀ during t ₃ , V _{1 is} assumed to be due to external factors such as temperature and humidity fluctuations.
As a new reference output V ₀ . In addition, when the freshness of the food is detected at J = 1, the output does not decrease because the odor exceeding the capacity of the deodorizer 18 is generated.
To maintain the previous reference output V _0.

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

The operation of the embodiment is shown in FIG. The solid line in the figure shows a state having a standard odor, and the broken line shows a state without odor. If there is an odor, the output reduction rate X due to the operation of the deodorizer 18
Is small, and X is large when there is no smell. Therefore, determining the additional deodorizing time t ₂ by the X. When the rate of decrease X of the sensor output when the deodorizer 18 is operated is equal to or less than α as indicated by the chain line on the right side of the figure, the display by the light emitting diode 24 is performed assuming that the freshness of the food in the refrigerator has been reduced. Although the value of α is 1.2 in the embodiment, it may be changed as appropriate according to the type of sensor, the capacity of the deodorizer 18, and the like.

In the embodiment, the specific one is described together with the specific numerical condition, but the present invention is not limited to this. For example, in the embodiment, the degree of odor was measured every time of deodorization. However, the degree of odor was measured about once a day. In other cases, the measurement of odor was omitted only by operating the deodorizer 18. You may do it. In this case, the operation duty ratio of the deodorizer 18 may be determined by measuring the odor, and the deodorizer 18 may be 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 output of the gas sensor accompanying the operation of the deodorizer, and deodorization is controlled. That is, the case where the decrease in the output is large is regarded as having a low odor concentration, and the case where the decrease in the output is small is regarded as having a high odor concentration. According to this detection method, a high output corresponding to the degree of the odor is obtained, and a highly reliable signal that is not affected by fluctuations in ambient temperature and humidity, fluctuations in the sensor over time, and the like is obtained. Further, according to the present invention, a display indicating a decrease in freshness of the food in the refrigerator is performed, and waste of the food is eliminated.

[Brief description of the drawings]

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

Continued on the front page (72) Inventor Yasunori Ono 1-3-5 Senba Nishi, Minoh City, Osaka Prefecture Inside Figaro Giken Co., Ltd. (72) Inventor Akira Yokoe 3--22 Takaidahondori, Higashi Osaka City, Osaka Matsushita Refrigerator (72) Inventor Katsuhiko Taki 3-22 Takaidamoto-dori, Higashiosaka-shi, Osaka Matsushita Refrigeration Machinery Co., Ltd. (56) References JP-A-1-219479 (JP, A) Jpn. JP, U)

Claims (1)

(57) [Claims] 1. A method for controlling a deodorizer provided in a refrigerator by detecting an odor with a gas sensor and detecting a degree of a decrease in the output of the gas sensor accompanying the operation of the deodorizer, wherein the decrease in the output of the gas sensor is large. It is assumed that the odor concentration is sometimes low, and the odor concentration is high when the decrease in the gas sensor output is small, the degree of odor is determined, the deodorizer is controlled according to the determined odor degree, and the gas sensor accompanying the operation of the deodorizer is determined. A method for controlling deodorization of a refrigerator, comprising: displaying a decrease in freshness of food when a decrease in output is equal to or less than an allowable value.