JPH0652149B2 - Temperature control method for constant temperature and high humidity refrigerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a constant temperature and high humidity refrigerator in which brine is used as a cooling medium, and effectively suppresses an increase in the temperature inside the refrigerator during the defrosting operation to allow the defrosting operation to proceed. Nevertheless, the present invention relates to a method for controlling the temperature inside the refrigerator in which the food material can be cooled and stored in a good condition without deterioration in freshness.

Prior art To store frozen foods such as fruits, vegetables, meat and fish in a refrigerator for a long period of time, and to thaw the frozen foods, generally, to suppress the temperature change in the refrigerator as much as possible, It is necessary to take measures to prevent the evaporation of water.

As a refrigeration system that meets this demand, a constant-temperature and high-humidity refrigerator that uses brine (antifreeze) as a cooling medium has been put into practical use. In this, the brine stored in the brine tank is cooled by an evaporator connected to a refrigeration system, and the cooled brine is circulated through the cooler to cool the inside of the refrigerator. This brine-cooled refrigerator can circulate a large amount of brine with a large specific heat to ensure a large cooling capacity compared to a normal refrigerator that uses an evaporator as a cooling source, and thus is suitable for cooling and storing a large amount of food. ing. Moreover, since the difference between the surface temperature of the cooler and the inside temperature can be reduced, it is possible to suppress the frost formation in which the moisture in the inside air is condensed on the surface of the cooler, and thus to keep the inside of the refrigerator at high humidity. You can

However, even with the brine circulation type cooler described above,
When the inside temperature is set to around 0 ° C or below 0 ° C, the surface temperature of the cooler is kept below 0 ° C, and it is inevitable that frost grows in layers on the surface of the cooler gradually. This frost lowers the high-humidity state of the inside of the refrigerator, and also hinders heat exchange between the cooler and the air in the refrigerator to reduce the cooling capacity. Therefore, it is necessary to detect the degree of frost formation by an appropriate means, stop the circulation of the brine, and heat the cooler by a defrosting acceleration means such as a heater to melt the frost. .

As means for detecting the degree of frost formation in this cooler,
Known are a direct detection method such as a capacitance type, a photoelectric type, and an electrode type, and a timer type indirect detection method that performs a defrosting operation at regular intervals. With either detection method, when the degree of frost formation is detected and defrosting operation is started, the operation of the refrigeration system and the circulation of brine to the cooler are stopped, and the heater for promoting defrosting is energized. To heat the cooler. As a result, the frost adhering to the cooler is melted, and when the surface temperature of the cooler rises to a predetermined temperature, the defrost thermostat detects this and stops energizing the heater. In order to prevent re-freezing of the melted water adhering to the cooler when the cooling operation is restarted, a certain draining time is provided after the heater is de-energized, and after this draining time has elapsed, the operation of the refrigeration system and brine to the cooler are performed. And restart the circulation to switch to cooling operation.

Problems to be Solved by the Invention In the above-mentioned constant temperature and high humidity refrigerator, when the defrosting operation starts, the inside of the refrigerator is not cooled by the cooler, and heat is radiated from the heater and the cooler heated by the heater and heat entering from the outside. The temperature inside the refrigerator gradually rises due to heat radiation from foodstuffs stored in the refrigerator. Further, even after the defrosting of the cooler is completed and the power supply to the heater is stopped, the cooling operation is not started during the preset draining time, and during this time, the residual heat of the heater further raises the internal temperature of the refrigerator. to continue.

In addition to the temperature rise in the refrigerator during this defrosting operation, it takes time to cool the refrigerator to the optimum temperature even if the cooling operation is restarted. Change due to the rise of. Therefore, it is difficult to store the food in the optimum temperature range, and there is a serious drawback that the freshness and quality are deteriorated.

Further, in a normal refrigerator in which an evaporator connected to a refrigerating device is used as a cooler, the evaporation temperature of the refrigerant is extremely low. Therefore, when the cooling operation is restarted after the defrosting operation is completed, water droplets are frozen again. Therefore, if a draining time is provided and an attempt is made to cope with this, the temperature inside the refrigerator rises to, for example, point P in FIG. 6, resulting in a drawback that the freshness of the food material is reduced.

OBJECT OF THE INVENTION The present invention has been proposed in order to preferably solve this problem in view of the above-mentioned drawbacks inherent in the internal temperature control during defrosting of a constant temperature and high humidity refrigerator, and is associated with defrosting operation. (EN) A means capable of effectively suppressing an increase in the temperature inside the refrigerator to reduce the temperature change in the refrigerator, thereby achieving the preservation of food in the optimum temperature range, and keeping the freshness and quality in a good state. The purpose is to

Means for Solving the Problems In order to overcome the above-mentioned problems and preferably achieve the intended purpose, the present invention cools brine in a brine tank by an evaporator connected to a refrigerating apparatus, and cools the brine. The brine is circulated to the cooler installed in the storage by operating the pump to perform the cooling operation inside the storage, and the growth degree of frost adhering to the surface of this cooler is detected to shift to the defrosting operation. A constant temperature and high humidity refrigerator configured to stop the circulation supply of brine to the cooler by stopping the operation of the pump and perform defrosting by the defrosting promoting means arranged in the vicinity of the cooler. When the defrosting in the cooler is completed, the defrosting promoting means stops its operation, and at the same time, the operation of the pump is restarted to restart the circulation supply of the brine to the cooler, thereby promoting the defrosting. Means to operate After a predetermined sealed time, characterized by restarting the cooling operation by the refrigeration system.

EXAMPLE Next, a brine cooling type constant temperature and humidity refrigerator will be illustrated as an apparatus capable of suitably implementing the internal temperature control method according to the present invention, and will be described below with reference to the accompanying drawings.

(Regarding Schematic Structure of Refrigerator) As shown in FIGS. 1 and 2, this refrigerator includes a box body 1 and a cooling unit section 10 which are partitioned in a lateral direction, and a top plate 11 is commonly arranged. ing. A storage case 1a for cooling and storing a stored product such as frozen food (hereinafter referred to as "foodstuff") is defined inside the box body 1, and a door 12 is pivotally supported at an opening of the storage case 1a so as to be openable and closable. There is. Further, a shelf (not shown) on which food materials are placed and the like are detachably provided horizontally inside the storage case 1a.

As shown in FIG. 2, the cooling unit unit 10 includes a refrigeration unit 4 including members such as a compressor CM, a fan motor FM ₃ and a condenser 3, a brine cooling unit 13 including a brine tank 6, and an inside of the refrigerator. An electric equipment box 17 having a temperature controller 15, a thermometer 16 and the like is provided.

In the cross section of the main part of the constant temperature and high humidity refrigerator according to the present embodiment shown in FIG. 2, a heat insulating material 20 is filled between the outer box 18 and the inner box 19 which form the box body 1, and the inner box 19 is filled with the image. A cooler 7 to which brine as a cooling medium is circulated and supplied is fixedly arranged on the upper left side inside the storage case 1a formed. A cooling duct 21 having an open left side is arranged below the cooler 7 to cover the cooler 7 in a non-contact state. A required opening 22 is formed on the right side of the cooling duct 21 as shown in the drawing, and the two air-cooling fan motors FM ₁ and FM ₂ (only one of which is shown in the drawing) arranged in the opening 22 keeps the inside air After being sucked from the gap on the left side of the cooling duct 21 and contacting the cooler 7 to perform heat exchange for cooling, it is blown out from the opening 22 and circulates as shown by the solid arrow to circulate the entire inside of the storage 1a. To cool.

As shown in FIG. 4, a defrost thermo Th ₁ for detecting the end of defrost and heaters H ₁ , H ₂ for accelerating defrost are provided near the cooler 7.
Further, a dew tray 27 is arranged below the cooler 7 so that water drops dropped from the cooler 7 during defrosting are collected and discharged to the outside of the refrigerator. The reference numeral 28 indicates a temperature-sensing portion of the in-compartment thermo Th ₂ which is arranged in a proper place in the interior.

(Brine Cooling Unit) The brine cooling unit 13 shown in FIG. 3 has a function of cooling the brine with the refrigerant from the refrigerating device 4 and circulatingly supplying the brine to the cooler 7 as a cooling medium. . The illustrated brine tank 6 is configured as a box-shaped container in which a heat insulating material 31 is filled between an outer box 29 and an inner box 30,
The upper opening is detachably attached by a lid 35 having a heat insulating material 34 interposed between the upper lid 32 and the inner lid 33. Further, each end edge portion of the upper lid 32 is bent at a right angle and fitted into the outer box 29 of the tank 6, so that the upper edge portion of the tank 6 and the inner lid 33 are in close contact with each other. The end of the upper lid 32 is detachably fixed to the tank outer box 29 via a bolt.

At the bottom of the side wall of the inner box 30 in the tank 6, a suction pipe 36
Is connected to one end and the other end is a brine circulation pump PM.
Is connected to the suction side of. The discharge side of the pump PM is in communication with the supply pipe 9 of the cooler 7. Further, a discharge pipe 37 that is bent in a key shape and opens downward is provided on the upper side wall of the inner box 30, and the other end of the discharge pipe 37 is connected to the return pipe 14 from the cooler 7. . The discharge pipe 37 and the suction pipe 36 are both covered with a heat insulating hose 38. Further, a support plate 39 formed in a concave shape is fixed to the bottom of the tank 6, and a coil-shaped evaporator 40 led out from the refrigerating device 4 is horizontally arranged on the support plate 39, so that a predetermined space is provided in the tank 6. The brine 8 stored at this liquid level can be cooled to the required temperature.

The brine tank 6 is arranged such that the liquid level of the brine 8 injected into the tank 6 is located below the cooler 7, and the cooler 7 and the tank are disposed during a defrosting operation described later. All the brine 8 remaining in the pipes connecting the cooling device 6 and the cooler 7 is configured to return to the brine tank 6.

(Regarding Refrigeration Circuit and Brine Circulation Circuit) FIG. 4 is a schematic system diagram showing respective pipelines of the refrigerant refrigeration circuit and the brine circulation circuit. In the figure, the refrigerant gas compressed by the compressor CM is liquefied by the condenser 3 and dehumidified by the dryer 41, and then the liquefied refrigerant is decompressed by the capillary tube 42, and the evaporator arranged in the brine tank 6 is shown. Evaporate in 40 to exchange heat with the brine 8 and cool the brine 8. The evaporated vaporized refrigerant returns to the compressor CM via the suction pipe. The symbol FM
₃ indicates a fan motor for the condenser 3.

Next, the brine circulation circuit will be described. The brine 8 stored in the brine tank 6 is cooled to a required temperature by the evaporator 40 connected to the refrigerating apparatus 4,
Circulation pump P via suction pipe 36 led out from tank 6.
After being sucked by M, it is supplied to the cooler 7 via the supply pipe 9 connected to the discharge side. This cooled brine 8
After cooling the cooler 7 and exchanging heat with the inside air, it is returned from the return pipe 14 to the tank 6 via the key-shaped discharge pipe 37.

FIG. 5 shows an electric control circuit of the refrigerator according to the present embodiment. In the figure, a cam timer TM is connected between the power supply lines A and B, and a movable contact provided on the power supply line B side of the cam timer TM. c is connected to the fixed contact a side during the cooling cycle by the timer drive motor M, and is switched to the fixed contact b side during the defrost cycle. Power between the supply line A and the connection point K, the contact Th ₂ in the internal thermo Th ₂
A compressor CM and a fan motor FM ₃ are connected in parallel between the connection point K and the fixed contact a. The thermo-contact Th ₂ -a has a temperature T in the refrigerator.
There is reaches a predetermined upper limit value T ₁ is opened to rise, closing reaches a predetermined upper limit value T _1. Further, it is controlled to be closed until the internal temperature T decreases and reaches a predetermined lower limit value T ₀ (T ₀ <T ₁ ), and is opened when it reaches the predetermined lower limit value T ₀ .

Fan motors FM ₁ and FM ₂ are connected in parallel between the power supply line A and the contact a of the cam timer TM. Further, between the power supply line A and the connection point L,
It is connected by a contact Th ₁ -b of the defrosting thermo Th ₁ , and heaters H ₁ and H ₂ and a relay X are connected in parallel between the connection point L and the fixed contact b of the cam timer TM.
Note that the contact Th ₁ -b of the defrosting thermo Th ₁ is closed when the temperature of the cooler 7 falls below a predetermined value and opens at a predetermined value above 8)
To be done.

A normally closed contact Xb that cooperates with the relay X is connected between the power supply line A and the connection point N, and a timer drive motor M and a pump motor PM are connected between the connection point M and the power supply line B. And are connected in parallel.

[Operation of Embodiment] Next, the actual operation of the constant temperature and humidity refrigerator according to this embodiment will be described with reference to the timing chart shown in FIG. Prior to the operation of the constant temperature and high humidity refrigerator, first, the lid 35 of the brine tank 6 is removed, and the brine 8 is injected. The injection amount is appropriate for the capacity of the brine in the circulation pipeline system and the tank 6. It is the sum of the amount that the liquid level is stored. After finishing the brine injection, the lid 35
Put on again.

When the power switch is turned on, the contact a- of Camtime TM
The cooling operation is started via the interval c, and the drive motor M of the cam timer TM is rotated via the normally closed contact Xb cooperating with the relay X to start counting the time limit. Note Since the inside temperature T is higher, the contact Th ₂ -a of the internal thermo Th ₂ is not closed, the compressor CM and the fan motor FM ₃ is activated operation of the refrigeration system of the refrigeration apparatus Be started. Further, the brine circulating pump PM is rotated through the normally closed contact Xb, sucks the brine 8 in the tank 6 from the suction pipe 36, and circulates and supplies the brine 8 to the cooler 7 from the discharge pipe 9.

The brine 8 that has been pumped by the pump PM and passed through the cooler 7 exchanges heat with the air in the cold storage, and then returns to the tank 6 from the discharge pipe 37 via the return pipe 14. Then, the returned brine 8 is mixed with the stored brine 8 cooled by the evaporator 40 in the tank 6, and is again circulated by the pump PM via the suction pipe 36. At this time, both the fan motors FM ₁ and FM ₂ in the refrigerator are rotating, so that the air in the refrigerator is forcibly brought into contact with the cooler 7 to exchange heat, and then circulates in the refrigerator, and so on. Due to this, the temperature inside the refrigerator gradually decreases.

When the circulation amount of the brine 8 is increased and the surface area of the cooler 7 is increased, the heat exchange amount with the inside air increases. Moreover, since the temperature difference between the inside temperature and the cooler 7 is extremely small, the amount of frost on the cooler 7 is reduced, and the high humidity can be maintained.

The inside temperature is lowered, the temperature T reaches the lower limit set temperature T ₀ of the internal thermo Th _2, thermo contact Th ₂ -a is opened to stop the compressor CM and the fan motor FM _3. Since the pump PM and the fan motors FM ₁ and FM ₂ continue to operate, the brine 8 in the tank 6 continues to circulate in the pipeline system, and the brine in the warehouse is circulated by the blower fans FM ₁ and FM ₂ . Heat exchange with air is continued to continue cooling the inside of the refrigerator.

By the way, the temperature T in the refrigerator rises with time due to heat entering from the outside, heat generated by the fan motors FM ₁ and FM ₂ , heat radiation from foods, etc., and thereby the temperature of the brine 8 that exchanges heat with the air in the refrigerator. To rise. When the internal temperature T rises to the upper limit set temperature T ₁ of the internal thermo Th ₂ ,
The thermo and contact Th ₂ -a is closed by the compressor CM and the fan motor FM ₃ is activated, the cooling operation is restarted.
By repeating the above cycle, the internal temperature is maintained between the upper limit set temperature T ₁ and the lower limit set temperature T ₀ .
Further, during this period, frost adheres to the surface of the cooler 7 and gradually grows in layers.

When the above-described cooling operation is repeated and a predetermined time has elapsed and the cam timer TM times out, the contact of the cam timer TM switches to the bc side and shifts to the defrosting operation of the refrigerator,
As a result, the compressor CM, the fan motors FM ₁ , FM ₂ , F
All of M ₃ stop. Since that is the case the temperature of the cooler 7 is sufficiently low, the defrosting thermo Th ₁ contact Th ₁ -
b is in the closed state. Therefore, the energization of the heaters H ₁ and H ₂ and the relay X is started. Further, when the relay X is excited, the normally closed contact Xb cooperating with the relay X is opened, and the pump PM and the timer drive motor M stop their rotations. The heating of the cooler 7 by the heaters H ₁ and H ₂ is sufficient for the outer surface only, and defrosting is performed in a short time. The frost adhering to the cooler 7 is melted into water droplets, which are dripped onto the dew tray 27. It is discharged to the outside of the refrigerator. When the pump PM is stopped, as described above, the cooler 7 is located above the brine liquid level in the tank 6, so that all the brine in the cooler 7 returns to the brine tank 6 and thus the brine 8 Is not heated by the heaters H ₁ and H ₂ .

The temperature of the cooler 7 rises when the frost is melted, the defrosting thermo Th ₁ detects this temperature rise, opens the contact Th _1- b, and energizes the heaters H ₁ , H ₂ and the relay X. Is cut off. When the relay X is deenergized, the normally-closed contact Xb cooperating with the relay X is closed again, and the energization of the pump PM and the timer drive motor M is started. Since the contact point of the cam timer TM is on the bc side at this point, the compressor CM,
None of the fan motors FM ₁ , FM ₂ and FM ₃ are operating. Then, by rotating the pump PM, the brine 8 in the brine tank 6 is circulated and supplied to the cooler 7. The brine 8 in the tank 6 is stored cold due to its large heat capacity. Therefore, even if the evaporator 8 is not positively forcibly cooled, the brine 8 is circulated through the cooler 7 to cool it and the vicinity of the cooler 7 It is possible to cool the heaters H ₁ and H ₂ arranged in the room to rapidly lower the internal temperature.

That is, as shown in the timing chart of FIG. 6, when the internal temperature T reaches point O, the frost in the cooler 7 is completely melted, and the operation of the defrosting thermo Th ₁ causes the heaters H ₁ ,
When the power supply to H ₂ is cut off, the pump PM is activated by closing the normally closed contact Xb, and the brine 8 is supplied to the cooler 7. As a result, it is possible to suppress an increase in the internal temperature due to the residual heat of the cooler 7 and the heaters H ₁ and H ₂ , and it is possible to reduce the temperature change in the internal compartment. The heater H ₁ ,
After the power supply to H ₂ is cut off, the cooler 7 of the brine 8 is
As a result of the circulation in FIG. 3, the internal temperature T continues to be substantially the same as the temperature at point O, as indicated by the solid line in the timing chart.

Here, the difference between the temperature of the brine 8 and the internal temperature T is about 1
It is controlled so that the temperature is around ~ 3 ° C, and O
Since the temperature of the spot is kept at about 0 to 2 ° C., even if the brine 8 is immediately supplied to the cooler 7, the temperature of the cooler 7 is 0.
It does not go below ℃, so the thawed water droplets will not freeze.

Further, the energization of the timer drive motor M is started, and after a while, the contact of the cam timer TM is switched to the ac side, and the above-described cooling operation is restarted. At this time, the internal temperature is only slightly higher than the upper limit set temperature T ₁ , and the time required to cool the stored food material to the optimum temperature can be shortened.

In the cooling operation described above, when the set temperature in the refrigerator is set to a temperature higher than 0 ° C, for example, 3 to 5 ° C, the temperature of the cooler 7 is higher than 0 ° C (the temperature of the brine 8 is 0 ° C).
(Because it becomes higher than that), frosting does not occur on the cooler 7. Therefore, even if the timer TM times out and enters the defrosting operation, the contact Th ₁ -b of the defrosting thermo Th ₁ remains open and the normally closed contact Xb remains closed. , The timer drive motor M and the pump PM are always operated.

In the present embodiment, during the defrosting operation period, the operation of the refrigeration system is stopped, and after the energization of the heaters H ₁ and H ₂ is cut off, the cooler 7 is cooled by using the cold storage of the brine 8. Although the refrigerator configured has been described, in a refrigerator having a small capacity of the brine 8 and a low heat insulation effect in the brine tank 6 (poor cold storage efficiency), the refrigerating device is operated during the defrosting operation period. Therefore, the temperature of the brine 8 may be kept constant.

Effect of the Invention As described above, the method for controlling the internal temperature of the constant temperature and high humidity refrigerator according to the present invention, when the defrosting in the cooler is completed during the defrosting operation and the defrosting promoting means stops its operation. At the same time, the circulating supply of brine to the cooler is restarted to cool the cooler. Therefore, it is possible to suppress the temperature rise in the refrigerator during the defrosting operation period to a low level, and it is possible to effectively prevent deterioration of freshness and deterioration of the food due to temperature rise. Further, when the next cooling operation is started, the internal temperature can be lowered to the set temperature in a short time.

Furthermore, because the temperature inside the refrigerator is set high, the temperature of the cooler is 0
If the temperature rises above ℃ and no frost is observed, the brine circulation pump does not stop even if the defrosting operation is started due to the time-up operation of the timer, so continue supplying brine. Since the inside of the refrigerator is cooled, the temperature inside the refrigerator hardly rises.

[Brief description of drawings]

1 is a front view showing a state in which a cover is removed from a cooling unit section of a constant temperature and high humidity refrigerator according to the present invention. 2 is a vertical sectional view showing the internal schematic structure of the refrigerator, FIG. 3 is a vertical sectional view of a brine tank, and FIG.
FIG. 5 is a schematic explanatory view showing a pipeline connection state of a brine circulation circuit incorporated in the refrigerator shown in FIG. 2 and a refrigerant circulation circuit from a refrigeration system, and FIG. 5 is an electric control for controlling the constant temperature and humidity refrigerator shown in FIG. A circuit diagram and FIG. 6 are timing charts for explaining the operation of the electric control circuit diagram shown in FIG. 1a ... Storage, 4 ... Refrigerator 6 ... Brine tank, 7 ... Cooler 8 ... Brine, 40 ... Evaporator PM ... Pump, H ... Heater

Claims (2)

[Claims] 1. A brine (8) in a brine tank (6) is cooled by an evaporator (40) connected to a refrigeration system (4), and this cooled brine (8) is operated by a pump (PM). Storage (1
The cooling operation is performed by circulating the cooling device (7) arranged in a) inside the refrigerator, and the defrosting operation is performed by detecting the growth degree of frost adhering to the surface of this cooling device (7), The circulating supply of the brine (8) to the cooler (7) is stopped by stopping the operation of the pump (PM), and defrosting is performed by the defrosting promoting means (H) arranged near the cooler (7). In the constant temperature and high humidity refrigerator configured to perform the defrosting in the cooler (7) during the defrosting operation, the defrosting promoting means (H) stops its operation, and at the same time, the pump (PM) Of the brine (8) to the cooler (7) by restarting the operation of
Restart the circulation supply of, the defrosting promoting means (H) after a predetermined time after stopping the operation,
A method for controlling a temperature inside a constant temperature and high humidity refrigerator, characterized in that the cooling operation by the refrigerating device (4) is restarted. 2. The method for controlling the internal temperature of a constant temperature and high humidity refrigerator according to claim 1, wherein the defrosting promoting means (H) is a heater.