JP2640050B2 - Failure prediction method for cooling storage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator, a refrigerated showcase, and a refrigeration show, which are provided with a refrigeration cycle in which a compressor, a condenser, a cooler and the like are connected in a ring shape and a refrigerant is enclosed to cool the inside of the refrigerator. The present invention relates to a cooling storage such as a case and a vending machine, and more particularly to a failure prediction method for predicting a failure which will occur in these cooling storages and generating an alarm.

[0002]

2. Description of the Related Art Conventionally, in this type of cooling storage, outside air is forcibly circulated to a condenser by a blower in order to secure a predetermined refrigerant condensing capacity in the condenser. On the other hand, dust is carried into the condenser at the same time by such ventilation,
Usually, a filter or the like is provided on the air suction side of the condenser.

When dust accumulates in the filter, it causes clogging, deteriorates the ventilation performance of the condenser, raises the temperature of the condenser, and reduces the condensation capacity, so that the refrigeration cycle is cooled by a predetermined amount in the cooler. You will not be able to demonstrate your ability. For this reason, for example, in Japanese Utility Model Publication No. 60-22305, a timer is used to warn the user and to prompt the user to clean the filter every certain period of use. However, the actual dust adhesion condition differs depending on the installation location, season, and use condition. Useless alerts can be issued.

Therefore, conventionally, a sensor is generally provided in the refrigerant outlet pipe of the condenser, and when the temperature of the condenser rises and the refrigerant outlet temperature becomes a high temperature such as + 50 ° C., an alarm is issued, The clogging due to dust is reported to the user, and the user is prompted to clean the filter and the like.

[0005]

However, in such a conventional alarm device, an alarm is issued after clogging reaches a limit state, that is, after the cooling capacity of the refrigeration cycle is completely lost, so that the food in the refrigerator is not provided. There is a risk that pain has already occurred.

Further, when the outside air temperature is low and the refrigeration cycle is lightly loaded, there is a margin in the cooling capacity even if clogging occurs to some extent. However, if the clogging occurs and the outside air temperature rises at a stretch the next day, for example, This time, the refrigeration cycle became heavily loaded, the cooling capacity was no longer ensured, and an alarm was eventually issued, and at that point, the food had sometimes started to deteriorate.

[0007] Such an abnormal situation due to a decrease in cooling capacity is caused not only by clogging of the condenser but also by leakage of refrigerant in the refrigeration cycle and abnormal frost formation on the cooler. The development of a method of predicting in advance was desired.

Accordingly, the present invention provides a failure prediction method for predicting that an abnormality will occur in the future, that is, leading to a failure, and issuing an alarm before an abnormal situation such that the cooling capacity of the cooling storage is lost occurs. The purpose is to provide.

[0009]

According to the first aspect of the present invention, there is provided a refrigeration cycle 3 in which a refrigerant is sealed by connecting a compressor 15, a condenser 1, a cooler 4 and the like in an annular manner. The cooling performance of the refrigeration cycle 3 in the cooling storage (showcase 5) including the blower 14 for forced ventilation, the sensor S1 for detecting the outside air temperature Ta, and the sensor S2 for detecting the refrigerant outlet temperature Tco of the condenser 1 is improved. The clogging amount of the condenser 1 in a state where it cannot be ensured or a predetermined safety degree from this limit is defined as the clogging amount, and the refrigerant outlet temperature Tco of the condenser 1 with respect to the outside air temperature Ta at this clogging amount is limited. Is measured to determine an alarm prediction line L3, and it is determined whether or not to output a clogging alarm for the condenser 1 based on the outputs of the sensors S1 and S2 using the alarm prediction line L3 as a threshold value. It is intended.

The method according to the second aspect of the present invention detects the refrigeration cycle 3 in which the refrigerant is sealed by connecting the compressor 15, the condenser 1, the cooler 4 and the like in an annular manner, and the refrigerant inlet temperature Tri of the cooler 4. The cooling performance of the refrigeration cycle 3 can be secured in a cooling storage (showcase 5) including a sensor S3 for detecting the refrigerant outlet temperature Tro of the cooler 4 and a sensor S1 for detecting the outside air temperature Ta. The refrigerant amount of the refrigeration cycle 3 in a state where the refrigerant has a certain level of safety from the limit at which the refrigerant has disappeared is set as the critical refrigerant amount, and the refrigerant inlet / outlet temperature difference Trd of the cooler 4 with respect to the outside air temperature Ta at this critical refrigerant amount is measured. To determine whether to output a refrigerant leak alarm for the refrigeration cycle 3 from the outputs of the sensors S1, S3, and S4 using the alarm prediction line L6 as a threshold. It is intended to determine.

A method according to a third aspect of the present invention provides a refrigeration cycle 3 in which a refrigerant is sealed by connecting a compressor 15, a condenser 1, a cooler 4 and the like in an annular manner, and a sensor S5 for detecting an internal temperature Tp.
And a cooling storage (showcase 5) having a sensor S1 for detecting the outside air temperature Ta, a limit at which cooling of the inside 6 cannot be ensured, or a cooler 4 having a predetermined safety degree from this limit. The amount of frost on the inside is defined as a limit frost amount, the inside temperature Tp for the outside air temperature Ta at this limit frost amount is measured to determine an alarm prediction line L9, and both the sensors are set with the alarm prediction line L9 as a threshold value. S1, S
It is to determine whether or not to output an excessive frost alarm of the cooler 4 from the output of No. 2.

[0012]

In each of the inventions, even when the detected value based on the output of each of the sensors S1 to S5 exceeds the warning prediction lines L3, L6, L9 when the outside air temperature Ta is low, the cooling capacity of the refrigeration cycle 3 is light, so the cooling capacity is small. Can afford. However, if the outside air temperature Ta rises in that state, it is certain that the load will be high and the cooling capacity will be completely lost, so that while the outside air temperature Ta is low, it can be predicted and an alarm can be issued.

[0013]

Next, an embodiment will be described with reference to the drawings. FIG. 1 is a correlation diagram between the suction air temperature of the condenser 1 for predicting clogging of the dust removal filter 2 of the condenser 1 described later, that is, the outside air temperature Ta and the refrigerant outlet temperature Tco of the condenser 1,
FIG. 2 is a correlation diagram between an outside air temperature Ta for predicting a refrigerant leak of the refrigeration cycle 3 described later and an inlet / outlet temperature difference (outlet temperature Tro−inlet temperature Tri = temperature difference Trd) of the cooler 4, and FIG. Correlation diagram between the outside air temperature Ta for predicting excessive frost on the vessel 4 and the inside temperature 6 Tp of the showcase 5,
FIG. 4 is a perspective view of the showcase 5, and FIG.
6 is a perspective view of the condenser 1 and the like, FIG. 7 is a block diagram of the control circuit 7, and FIG. 8 is a flowchart showing software of the microcomputer 8.

Referring to FIGS. 4 to 6, a showcase 5 as an embodiment of a cooling storage to which the present invention is applied is a so-called dipping case of ice cream, and an insulated box having an inside 6 which opens upward inside. The cooler 4 of the refrigeration cycle 3 is attached to the outside of the inner box 11 of the body 10, and the upper opening is closed by a slide door 12 so as to be openable and closable. A machine room 13 is formed on one lower side of the heat insulating box 10, and the condenser 1, the condenser blower 14, the compressor 15, and the filter 2 shown in FIG. 6 are provided in the machine room 13.

The compressor 15, the condenser 1, the decompressor and the cooler 4 (not shown) are connected in a ring shape, and a refrigerant is sealed therein to constitute a well-known refrigeration cycle 3. The blower 14 for the condenser is operated, sucks outside air from the filter 2 side as shown by the arrow in FIG. 6, cools it by passing through the condenser 1, and condenses the internal high-temperature high-pressure gas refrigerant.
Further, the compressor 15 is also cooled on the downstream side.

On the upstream side of the filter 2 of the condenser 1, there is provided an outside air temperature sensor S 1 for detecting the temperature of the air sucked into the condenser 1, that is, the outside air temperature Ta. A condenser refrigerant outlet temperature sensor S2 for detecting the refrigerant outlet temperature Tco of the condenser 1 is provided.

An inlet temperature sensor S3 for detecting the temperature Tri of the refrigerant is provided on the refrigerant inlet side of the cooler 4, and an outlet temperature sensor for detecting the temperature Tro on the refrigerant outlet side of the cooler 4. S4 is attached. Further, on the load line LD in the refrigerator 6, a refrigerator temperature sensor S5 for detecting the refrigerator temperature Tp is attached.

In FIG. 7, a microcomputer 8
The output of each of the sensors S1 to S5 is input to (this may be built in the showcase 5 or may be constituted by an external personal computer), and an alarm display 17 is connected to the output. I have. Further, the microcomputer 8 may be connected to the central monitoring host computer 18 via a communication line, and may be centrally managed at the monitoring base of the chain store.

Next, the correlation diagram of FIG. 1 will be described. FIG.
The horizontal axis represents the outside air temperature Ta (° C.), and the vertical axis represents the refrigerant outlet temperature Tco (° C.) of the condenser 1. A curve L1 indicated by a solid line in the drawing indicates a correlation between the outside air temperature Ta in a state where the filter 2 is not clogged at all and the refrigerant outlet temperature Tco of the condenser 1.
When the outside air temperature Ta is low, the refrigerant outlet temperature Tco is also low, and increases as the outside air temperature Ta increases.

On the other hand, a curve L2 indicated by a broken line in the figure
Shows the correlation between the temperature Ta and Tco at the limit of clogging of the filter 2 at which the desired cooling performance is no longer ensured, and the refrigerant outlet temperature Tco of the condenser 1 is represented by the curve L2
If it is higher, the inside of the refrigerator 6 will be defectively cooled. The reason that the interval between the curves L1 and L2 is wide at low outside air temperature such as winter and narrow at high outside air temperature such as summer is because the load of the refrigeration cycle 3 is small at low outside air temperature and there is room for cooling capacity. On the other hand, at a high outside air temperature, the load is large, and there is no room for the cooling capacity.

The high outside air temperature of the curve L2, for example, +30
At 3 ° C. below the temperature Tco (+ 50 ° C.) at 100 ° C.
47 ° C.), the clogging amount corresponding to this point A is defined as the limit clogging amount, and the temperature Ta is changed to change the correlation curve between the temperature Ta and Tco at the limit clogging amount of the filter 2 passing through the point A by a one-dot chain line. This is set as the warning prediction line L3. This warning prediction line L3 is obtained in advance by an experiment and stored in the microcomputer 8 or the host computer 18.

Next, the operation of predicting the clogging failure of the filter 2 will be described with reference to the flowchart of the microcomputer 8 shown in FIG. The microcomputer 8 determines in step 20 based on the outputs of the sensors S1 and S2, for example, 1
Sampling is performed once a time, and a daily average of the data is taken in step 21 to obtain 10 data as shown in the set indicated by Q1 in FIG.
In step 22, each data is compared with the alarm prediction line L3 (if it is in the host computer 18, it is called from there).
If o is beyond the warning prediction line L3, step 2
At 3, an alarm is displayed on the alarm display 17 to indicate that the filter 2 is clogged.

Therefore, no alarm is generated in the set of Q2 in FIG. 1, and an alarm is generated in the set of Q3.
The reason for making the determination by averaging the data in this way is to prevent malfunction due to noise.

Here, in the set of Q3, the curve L2
Since the outside air temperature Ta is in the range of + 24 ° C. to + 27 ° C., there is still room for cooling capacity with this amount of clogging. However, if the outside air temperature Ta rises to 30 ° C. while keeping the clogging amount, the condenser refrigerant outlet temperature Tco falls within 3 ° C. of + 50 ° C., and there is no room for cooling capacity.

As described above, according to the method of the present invention, it is possible to predict a cooling failure that will occur at the high outside air temperature Ta from the refrigerant outlet temperature Tco where the outside air temperature Ta is still low.

Here, in the sampling of the temperature, it is necessary to operate the compressor 15 and take in data at the time when the refrigeration cycle 3 is stabilized, that is, immediately before the stop of the compressor 15. As the method, it is conceivable to determine the stop of operation by the compressor relay or to determine from the data change rate. The reason why the warning prediction line is determined to be the curve L3 below the curve L2 is to secure a certain degree of safety from the limit curve L2. An alarm prediction line may be used.

Next, the correlation diagram of FIG. 2 will be described. FIG.
The horizontal axis represents the outside air temperature Ta (° C.), and the vertical axis represents the refrigerant inlet / outlet temperature difference Trd (° C.) of the cooler 4. A curve L4 indicated by a solid line in the drawing indicates a correlation between the outside air temperature Ta and the temperature difference Trd in a state where, for example, 600 g of the refrigerant is sealed in the refrigeration cycle 3 and there is no leakage. When the refrigerant amount is sufficient and evaporation is performed from the inlet to the outlet of the cooler 4,
Regardless of the outside air temperature Ta, the refrigerant inlet / outlet temperature difference Trd of the cooler 4 is 0 ° C.

On the other hand, a curve L5 indicated by a broken line in the figure indicates a limit refrigerant amount (for example, 150 ° C.) at which a refrigerant leak occurs in the refrigeration cycle 3 and a desired cooling performance is not ensured in the cooler 4.
2 shows a correlation between the temperature Ta and the temperature difference Trd in the state of “g lost”. The fact that the temperature difference Trd is above the curve L5 means that the amount of the refrigerant is small, evaporation has been completed only at the inlet of the cooler 4, and no evaporation has been performed at the outlet. Only a limited area exerts a cooling effect, and the inside of the refrigerator 6 has poor cooling.

Next, a curve L5 at the outside air temperature + 30 ° C.
A point B is determined 10 ° C. below the temperature difference 25 ° C.
The refrigerant amount (for example, a state in which 50 g has been lost) at the above is set as the limit refrigerant amount, the temperature Ta is changed, and a correlation curve between the temperature Ta and the temperature difference Trd at this refrigerant amount is drawn as a one-dot chain line, which is drawn to the alarm prediction line L6. And The reason why the temperature difference Trd is small in the state where the outside air temperature Ta is low is that the load on the refrigeration cycle 3 is reduced and the amount of the refrigerant in the refrigerator can be reduced with a small amount of refrigerant. This warning prediction line L6 is obtained in advance by an experiment and stored in the microcomputer 8 or the host computer 18.

The refrigerant leakage failure prediction operation of the microcomputer 8 is performed by using the warning prediction line L6 in the same manner as the above-described flowchart. That is, the microcomputer 8 performs the following operations based on the outputs of the sensors S1, S3, and S4.
For example, the data is sampled once an hour, the data is averaged for one day, and the data is accumulated for 10 days as shown by a set indicated by Q4 in FIG. If the temperature difference Trd exceeds the warning prediction line L6 for 7 days or more out of 10 days, the warning display 17 warns of refrigerant leakage.

Here, in the set of Q4, the curve L5
Since the outside air temperature Ta is in the range of + 20 ° C. to + 26 ° C., the cooling capacity still has a margin with this amount of refrigerant. However, if the outside air temperature Ta rises to + 30 ° C. with this amount of refrigerant, the cooler inlet / outlet temperature difference Trd approaches 25 ° C. within 10 ° C., and there is no room for cooling capacity.

As described above, according to the method of the present invention, the cooler inlet / outlet temperature difference T when the outside air temperature Ta is still low.
From rd, it is possible to predict a cooling failure that will occur at the high outside air temperature Ta.

Here, the sampling of the temperature is performed when the compressor 15 is operated and the refrigeration cycle 3 is stabilized.
That is, it is necessary to take in the data immediately before the compressor 15 stops. The reason why the warning prediction line is determined to be the curve L6 below the curve L5 is to secure a certain degree of safety from the limit curve L5. An alarm prediction line may be used.

Next, the correlation diagram of FIG. 3 will be described. FIG.
The horizontal axis represents the outside air temperature Ta (° C.), and the vertical axis represents the internal temperature T.
Take p (° C). A curve L7 indicated by a solid line in the drawing shows a correlation between the outside air temperature Ta and the inside temperature Tp in a state where no frost is formed inside the inner box 11. Here, the compressor 15 is operated by the thermostat irrespective of the outside air temperature Ta, and the set temperature -15
It is maintained at ° C.

On the other hand, a curve L8 indicated by a broken line in the figure indicates a temperature T at a limit frost amount at which a desired cooling performance is not ensured.
The correlation between a and Tp is shown, and if the inside temperature Tp is higher than the curve L8, the inside 6 becomes completely defective in cooling.

The high outside air temperature of this curve L8, for example, +30
Point C (-) at 2 ° C below the internal temperature Tp (-8 ° C) at
10 ° C.), the amount of frost corresponding to this point C is defined as the limit frost amount, the temperature Ta is changed, and the correlation curve between the temperature Ta and Tp at the amount of frost passing through the point C is drawn as shown by a chain line. ,
This is designated as a warning prediction line L9. The reason that the inside temperature Tp is reduced in the state where the outside air temperature Ta is low is that the load of the refrigeration cycle 3 is light. The alarm prediction line L9 is obtained in advance by an experiment and stored in the microcomputer 8 or the host computer 18.

The operation of the microcomputer 8 for predicting an excessive frost failure is basically the same as that described above, but it is assumed that no clogging of the filter 2 or failure of refrigerant leakage has occurred. On the basis of the outputs of the sensors S1 and S5, for example, the data is sampled once an hour, the data is averaged for one day, and accumulated for 10 days as shown by a set indicated by Q5 in FIG. 3, and each data and the warning prediction line L9 ( If it is in the host computer 18, call it from there) and compare it with the alarm prediction line L
If it exceeds 9, an alarm indicator 17 warns of excessive frost on the cooler 4 (inside the inner box 11).

Here, in the set of Q5, the curve L8
Since the outside air temperature Ta is in the range of + 21 ° C. to + 24 ° C., there is still room for cooling capacity with this amount of frost. However, assuming that the outside air temperature Ta rises to 30 ° C. while keeping this frost amount, the inside temperature Tp becomes −
It will be 10 ° C. and there will be no room for cooling capacity.

As described above, according to the method of the present invention, it is possible to predict a cooling failure that may occur at the high outside air temperature Ta from the inside temperature Tp when the outside air temperature Ta is still low.

The reason why the warning prediction line is determined to be the curve L9 below the curve L8 is the limit of the curve L8.
This is to ensure a certain degree of safety, and when such a degree of safety is not required, the curve L8 may be used as a warning prediction line.

In the embodiment, the present invention is applied to a showcase. However, the present invention is not limited to this, and the method of the present invention is effective in various cooling storages.

[0042]

According to the method of the present invention, a failure of a cooling storage that will surely occur at a high outside air temperature while the outside air temperature is still low is predicted, and the user is warned by an alarm. Therefore, it is possible to prevent food in the refrigerator from being damaged due to poor cooling.

[Brief description of the drawings]

FIG. 1 is a correlation diagram between an outside air temperature and a refrigerant outlet temperature of a condenser.

FIG. 2 is a correlation diagram between an outside air temperature and a temperature difference between an inlet and an outlet of a cooler.

FIG. 3 is a correlation diagram between the outside air temperature and the inside temperature of the showcase.

FIG. 4 is a perspective view of a showcase.

FIG. 5 is a longitudinal sectional view of a showcase.

FIG. 6 is a perspective view of a refrigeration cycle such as a condenser.

FIG. 7 is a block diagram of a control circuit.

FIG. 8 is a flowchart showing software of the microcomputer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condenser 2 Filter 3 Refrigeration cycle 4 Cooler 5 Showcase 6 Interior 8 Microcomputer 14 Condenser blower 15 Compressor 17 Alarm display S1 Outside air temperature sensor S2 Condenser refrigerant outlet temperature sensor S3 Inlet temperature sensor S4 Outlet temperature sensor S5 Internal temperature sensor L3 Warning prediction line L6 Warning prediction line L9 Warning prediction line

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-113261 (JP, A) JP-A-63-15067 (JP, A) JP-A-2-247472 (JP, A) JP-A-61- 101781 (JP, A) JP-A-62-248985 (JP, A)

Claims (3)

(57) [Claims] 1. A refrigeration cycle in which a compressor, a condenser, a cooler and the like are connected in a ring shape and a refrigerant is sealed therein, a blower for forcibly ventilating the condenser, a sensor for detecting an outside air temperature, and the condenser. In the cooling storage provided with a sensor for detecting the refrigerant outlet temperature, a limit at which the cooling performance of the refrigeration cycle cannot be ensured, or a clogging amount of the condenser having a predetermined safety degree from this limit is clogged. The alarm prediction line is determined by measuring the refrigerant outlet temperature of the condenser with respect to the outside air temperature at the limit clogging amount, and the alarm prediction line is determined as a threshold value, and the output of the two sensors is used to determine the alarm prediction line. A failure prediction method for a cooling storage that determines whether to output a clogging alarm. 2. A refrigeration cycle in which a compressor, a condenser, a cooler and the like are connected in a ring shape and a refrigerant is filled therein, a sensor for detecting a refrigerant inlet temperature of the cooler, and a refrigerant outlet temperature of the cooler. In the cooling storage provided with the sensor for detecting and the sensor for detecting the outside air temperature, the limit at which the cooling performance of the refrigeration cycle cannot be ensured, or the refrigerant amount of the refrigeration cycle having a predetermined safety degree is limited from this limit. The amount of refrigerant, the refrigerant inlet / outlet temperature difference of the cooler with respect to the outside air temperature at the limit refrigerant amount is measured to determine a warning prediction line, and the refrigeration cycle is determined from the output of each sensor using the warning prediction line as a threshold. Prediction method for determining whether to output a refrigerant leak alarm for a cooling storage. 3. A cooling storage having a refrigeration cycle in which a refrigerant is sealed by connecting a compressor, a condenser, a cooler, and the like in a ring, a sensor for detecting an inside temperature, and a sensor for detecting an outside air temperature. In the above, a limit at which cooling in the refrigerator cannot be ensured, or an amount of frost on the cooler having a predetermined degree of safety from this limit is defined as a limit frost loss, and the refrigerator with respect to the outside air temperature at the limit frost formation amount. A failure prediction method for a cooling storage, which determines an alarm prediction line by measuring the internal temperature and determines whether to output an overfrost alarm of the cooler based on the outputs of the two sensors using the alarm prediction line as a threshold value. .