JPS624627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an open storage case for freezing and refrigeration.

The open-air case is equipped with a refrigerator evaporator in the case body, and the cooled air exchanges heat with the evaporator to circulate and ventilate it inside the refrigerator, forming a cold air curtain at the front opening of the case body. By doing so, it is configured to keep the products lined up inside the refrigerator cold while preventing outside heat from entering.

On the other hand, a large proportion of the heat load of an open-air case is due to the heat entering from the outside air, and during cold storage operation, moisture contained in the outside air condenses on the surface of the evaporator, causing frost. Moreover, as the amount of accumulated frost on the evaporator increases, the heat exchange efficiency of the evaporator decreases.Furthermore, if frost clogging occurs between the fins of the evaporator, which is a plate-finned coil, it will significantly impede ventilation. Frost formation causes a significant drop in cold retention properties, such as deterioration of curtain performance.

For this reason, in a normal open case,
After a predetermined period of cold storage operation, the refrigerator is temporarily stopped, and defrosting heat is applied from the outside using a well-known defrosting method such as an electric heater, hot gas, or off-cycle defrosting method, and the ice is removed from the evaporator. The frost is melted and removed. However, in this case, the evaporator does not operate during the defrosting period, and defrosting heat is applied from the outside, so an increase in the temperature inside the refrigerator is unavoidable, resulting in an increase in the temperature of the products inside the refrigerator. It turns out. Moreover, an increase in product temperature causes product quality deterioration, so how to defrost smoothly while suppressing the effect on product temperature rise in open case cases is important in determining the quality of the cold storage performance of the case. This has become a major issue.

As a countermeasure to this problem, one condensing unit is equipped with two evaporators in the case body, and each evaporator is switched and controlled so that it runs alternately in cooling operation.
In addition, an operating system has already been proposed in which one is performing a cooling operation while the other is defrosting.

According to this system, since one of the two evaporators is always in cooling operation, the show case can continue to operate in a cold state throughout the entire period of operation, making it possible to maintain the appropriate temperature of the product.

However, in the conventional defrosting method described above, the defrosting heat source for both evaporators is a high-temperature refrigerant gas or liquid refrigerant in the refrigeration cycle, and defrosting is performed using the sensible heat of the refrigerant. That is, while one evaporator of one condensing unit is being operated for cooling, high-pressure refrigerant is passed through the other evaporator.
However, switching the refrigeration cycle between the two evaporators and condensing units as described above not only requires a complicated switching valve mechanism, but also causes problems such as liquid back-up, making it difficult to switch operations smoothly. This is difficult to do, and furthermore, depending on the configuration of the refrigerant circuit, refrigerant stagnation may occur within the system.

The present invention has been made in consideration of the above points, and its purpose is to enable smooth alternating operation of the two evaporators installed in the case body without any operational troubles, and to simplify the refrigerant circuit configuration. The object of the present invention is to obtain a new refrigerated case with excellent cold storage performance.

The present invention will be described in detail below based on illustrated embodiments.

First, in FIG. 1, a first partition wall 3a and a second partition wall 3b are provided on a part of the outside thereof between an outer box 1 and an inner box 2 of the case body.
b: Inner duct 4A, lower outer duct 4B, upper outer duct 4C, middle duct 4D
are separated. An inner evaporator 5A and an inner fan 6A are housed in the inner duct 4A, and the inner air curtain A is blown from the air curtain outlet to the air curtain suction port through the inner duct to the front opening of the case body. Further, a middle evaporator 5B and a middle fan 6B are housed in the middle duct 4D, and a middle air curtain B is blown out through the middle duct. On the other hand, the outer duct 4C has one end opened at the intermediate branch point 7 on the upstream side of the middle evaporator 5B and the middle fan 6B in the middle duct 4B, and the other end opened at the air curtain outlet of the case body. It is partitioned around the outer periphery, and a reversible outer fan 6C is housed here. When the outer fan 6C is rotated in the normal direction, an outer air curtain C is blown out, and when the outer fan 6C is rotated in the reverse direction, the outside air sucked from the air curtain outlet is forced into the middle duct 4D and blown.

Next, the refrigerant circuit of the refrigeration cycle including the evaporators 5A and 5B will be described. First, in the embodiment shown in FIGS. 2a and 2b, the evaporators 5A and 5B are connected in series with the pressure reducing elements 8A and 8B as shown in the figure to a condensing unit 9 consisting of a compressor and a condenser. Inner evaporator 5A close to the discharge side as seen
A solenoid valve 10 is connected to the pressure reducing element 8A, and a solenoid valve 11 is connected in parallel to the middle evaporator 5B including the pressure reducing element 8B so as to form a bypass circuit. The refrigerant circuit operation switching operation is performed as shown in the time chart of FIG. That is, while the refrigerator is in continuous operation, the inner fan 6A, the outer fan 6C, and the electromagnetic valves 10 and 11, which are valve mechanisms for switching the operation of the refrigeration cycle, are switched and controlled at a predetermined cycle. To explain this with reference to the time charts of FIGS. 2a and 2b and FIG. 4, in FIG. 2a, the solenoid valve 10 is OFF, the solenoid valve 11 is ON, and the outer fan is reversed. Therefore, the refrigerant flows in the order of the arrows from the condensing unit 9 to the pressure reducing element 8A to the inner evaporator 5A to the electromagnetic valve 11 to the condensing unit 9, forming a refrigeration cycle, and operating the inner evaporator 5A for cooling. On the other hand, no refrigerant is supplied to the middle evaporator 5B, and the outer fan 6C is reversed.
arrow drawn through the air curtain outlet
The outside air C' is forced into the middle duct 4D, and after the middle evaporator 5B is washed away by the air blown by the middle fan 6B, an air curtain B is blown out on the front surface of the case body. In this process, the high-enthalpy outside air gives defrosting heat to the middle evaporator 5B to melt and remove the frost adhering to the surface. Note that the refrigerant remaining in the middle evaporator 5B is gasified and sucked into the condensing unit and recovered. After a predetermined period of time has elapsed in this operating state, the middle evaporator 5B is switched to the cooling operation and the inner evaporator 5A is switched to the defrosting operation, as shown in FIG. 2b. In this state, the inner fan 6A is stopped, the outer fan 6C rotates normally, and the solenoid valves 10 and 11 are switched ON and OFF. Therefore, the refrigerant flows in the order of condensation unit 9→electromagnetic valve 10→inner evaporator 5A→pressure reducing element 8B→middle evaporator 5B→condensation unit 9 to form a refrigeration cycle, and the middle evaporator 5B is operated for cooling. On the other hand, the high-pressure liquid refrigerant flows through the inner evaporator 5A, and the sensible heat of the refrigerant is used as defrosting heat to melt and remove the frost adhering to the surface. Further, the outer fan 6C rotates normally and further blows out an outer air curtain C to the outside of the middle air curtain B. If the operations shown in Figure 2 a and b are periodically switched alternately in this way, one evaporator performs removal while the other operates to cool the refrigerated case, keeping the products on display in the refrigerator. Can be cooled continuously. Moreover, since a two-layer cold air curtain is always blown out from the front of the case body, it is highly effective in blocking outside air from entering the refrigerator.

In contrast to the embodiment shown in FIG. 2, the embodiment shown in FIGS. 3a and 3b uses hot gas as a defrosting heat source for the inner evaporator 5A. For this purpose, in addition to the liquid discharge line, a hot gas line is drawn out from the condensing unit 9 between the compressor and the condenser, and piping is connected between the condensing unit 9 and each evaporator 5A, 5B as shown in the figure. are doing. Note that 12,1 in the figure
3 and 14 are electromagnetic valves of the operation switching valve mechanism, 15 is a check valve, and 16 is a pressure reducing check valve inserted as necessary. A time chart of the operation switching operation using such a refrigerant circuit configuration is shown in FIG. As is clear from FIGS. 3a and 3b and FIG. 5, in the operating state shown in FIG. 3a, the inner evaporator 5A is in cooling operation, and the middle evaporator 5B is performing pneumatic defrosting by forced air blowing of outside air. . On the other hand, in the operating state shown in FIG. 3b, the middle evaporator 5B is in cooling operation,
Hot gas flows through the inner evaporator 5A, and its sensible heat is used to defrost the air. In the process of passing through the inner evaporator 5A, the hot gas exchanges heat with the frost, condenses and liquefies, and then passes through the check valve 15 and joins the liquid refrigerant that has passed through the condenser, and flows through the middle evaporator 5B during cooling operation.
sent to. Also, in this embodiment, as in the embodiment shown in FIG. 3, two layers of cold air curtain are always blown out from the front opening of the case body. Furthermore, the second
In each of the embodiments shown in Figs. and 3, a high and low speed two-speed motor fan is adopted as the middle fan 6B, and when defrosting the middle evaporator 5B when the outer fan 6C reverses, the middle fan 6B is decelerated to blow out the middle air curtain B. It is best to maintain the appropriate air volume.

As described above, according to the present invention, by alternately running the two evaporators in a cooling operation, it is possible to continue the cold operation state with almost no influence from frost formation, and to maintain the appropriate temperature of the products displayed in the warehouse. I can do it. In addition, of the two evaporators, one defrosts using the sensible heat of the refrigerant, while the other performs pneumatic defrosting using outside air heat, which simplifies the refrigeration cycle switching mechanism that accompanies operation switching. The system can be configured and the operation can be switched smoothly without any operational troubles. In addition, the structure is configured to forcibly introduce outside air by providing an outer fan and a reversible outer fan, which has a high defrosting effect and shortens defrosting time, which is advantageous in terms of cold storage performance. Since the air outlet is formed at the front opening of the main body, it has many effects such as high outside air ventilation and cutting effect, and can greatly contribute to improving the cold storage performance of the refrigerated open shower case.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the basic structure of an embodiment of the present invention, Figs. 2 a and b are explanatory diagrams of operation including a refrigerant circuit, and Figs. 3 a and b are refrigerant circuits of an embodiment different from Fig. 2. 4 and 5 are driving operation time charts of the embodiments shown in FIGS. 2 and 3, respectively. 1...Outer box of the case body, 2...Inner box, 3a...
...First partition, 3b...Second partition, 4A...Inner duct, 4B...Lower outer duct, 4C...
...Outer duct, 4D...Middle duct, 5A,
5B...evaporator, 6A, 6B, 6C...fan,
8A, 8B... pressure reducing element, 9... condensation unit,
10 to 14... Solenoid valves of the operation switching valve mechanism.

Claims (1)

[Claims] 1 A first partition wall is provided between the outer box and the inner box of the case main body which is approximately U-shaped and has an opening on one side.
An inner duct is formed between the partition wall and the inner box with both ends facing the opening and serving as an air outlet and a suction port for blowing out the inner air curtain, and an inner evaporator and an inner fan are disposed within the inner duct. , and a second partition is provided that separates the air from the first partition and the outer box from the inlet facing the opening and has a branch point leading to the air outlet, and the second partition and the first A middle duct is formed between the inner air curtain and the partition wall, one end of which serves as an outlet for blowing out the middle air curtain at the front of the inner air curtain, and the other end of which opens at the branch point. A container and a middle fan are disposed, and further an outgut is formed between the first and second partition walls and the outer box, the ends of which form an air outlet and a suction port for blowing out the air curtain to the front surface of the middle air curtain. and the second
A fan is provided in the outduct side formed by the partition wall and the outer wall, and during cooling operation of the inner evaporator, the inner evaporator is supplied with refrigerant and the inner fan is rotated in the forward direction to cool the inner evaporator. cool air is blown out from the inner air outlet to form an inner air curtain, and at the same time, the supply of refrigerant to the middle evaporator is stopped, the middle fan is rotated in the forward direction, and the outer fan is rotated in the reverse direction to direct outside air to the middle evaporator. Forced air is blown to the middle evaporator, and after washing the middle evaporator, it is blown out from the middle air outlet to form a middle air curtain to perform pneumatic defrosting using outside air heat. The high-pressure side refrigerant is made to flow through the evaporator, the inner fan is stopped, and the middle evaporator is supplied with refrigerant, and the middle fan and outer fan are rotated in the forward direction to blow cold air through the middle evaporator. The inner and middle evaporators are piping connected to the condensing unit via an operation switching valve mechanism so that a middle air curtain is blown out from the outlet and an outer air curtain is formed to perform sensible heat defrosting of the refrigerant using the sensible heat of the refrigerant. A refrigerated open case, characterized in that a refrigerating cycle is configured, and cooling and defrosting are periodically and alternately switched between an inner evaporator and a middle evaporator to perform cold preservation operation.