Cooling warehouse

Abstract

In a refrigerator equipped with two separate refrigeration systems, the storage chamber is efficiently cooled while preventing temperature variations and ensuring a uniform temperature throughout the storage chamber. [Solution] The cooling cabinet of the present invention comprises a cabinet body 1 in which a storage chamber 4 is defined inside, and a first refrigeration device 8 and a second refrigeration device 9 for cooling the storage chamber 4. An upper heat exchange chamber 33 is partitioned in the upper half of the storage chamber 4, and a lower heat exchange chamber 40 is partitioned in the lower half of the storage chamber 4. The upper heat exchange chamber 33 is provided with an evaporator 15 of the first refrigeration device 8 and an upper circulation fan 35 that supplies air to the evaporator 15 and forms an airflow that circulates in the upper region of the storage chamber 4. The lower heat exchange chamber 40 is provided with an evaporator 22 of the second refrigeration device 9 and a lower circulation fan 45 that supplies air to the evaporator 22 and forms an airflow that circulates in the lower region of the storage chamber 4.

Description

Technical Field

[0001] The present invention relates to a refrigerator in which a storage chamber is cooled by two independent refrigeration devices.

Background Art

[0002] This type of refrigerator is disclosed, for example, in Patent Document 1. The refrigerator (cooling storage device) of Patent Document 1 includes a refrigerator body (refrigerator casing) having a storage chamber inside, a first refrigeration device (first refrigerant circuit) for cooling the storage chamber, a second refrigeration device (second refrigerant circuit), and the like. The evaporator constituting the first refrigeration device is installed in a heat exchange chamber formed along the ceiling surface of the storage chamber, and the air in the storage chamber is fed toward the evaporator by a fan motor that forms an air flow circulating in the storage chamber, so that heat exchange is directly performed between the air and the evaporator to cool the air. Further, the evaporator constituting the second refrigeration device is installed inside the lower over-half part of the refrigerator body so as to surround the storage chamber, and the air circulating in the refrigerator by the air flow generated by the fan motor indirectly exchanges heat with the evaporator by touching the inner wall of the storage chamber, thereby being cooled.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As in the cooler described in Patent Document 1, if two independent refrigeration systems are installed, and the evaporators of each system are placed above and below the storage chamber, the refrigeration capacity can be increased compared to a configuration where the storage chamber is cooled by a single refrigeration system, and the storage chamber can be kept at a lower temperature. However, in the cooler described in Patent Document 1, the evaporator installed above the storage chamber directly exchanges heat with the air in the storage chamber, while the evaporator installed below the storage chamber indirectly exchanges heat with the air in the storage chamber via the inner wall of the storage chamber. Therefore, the heat exchange efficiency of the lower evaporator is inevitably lower than that of the upper evaporator, and the effect of increasing the refrigeration capacity by using two refrigeration systems cannot be fully obtained. In addition, in the bottom part of the storage chamber far from the fan motor, the force of the airflow from the fan motor weakens, causing air to stagnate and temperature unevenness to occur. Furthermore, the temperature unevenness becomes more pronounced because the air near the inner wall of the storage chamber is actively cooled.

[0005] The objective of the present invention is to efficiently cool the storage chamber in a cooler equipped with two refrigeration systems, while preventing temperature unevenness and ensuring a uniform temperature within the storage chamber. [Means for solving the problem]

[0006] The present invention provides a cooler comprising a cooler body 1 in which a storage chamber 4 is defined, and a first refrigeration device 8 and a second refrigeration device 9 for cooling the storage chamber 4. An upper heat exchange chamber 33 is partitioned in the upper half of the storage chamber 4, and a lower heat exchange chamber 40 is partitioned in the lower half of the storage chamber 4. The upper heat exchange chamber 33 is provided with an evaporator 15 of the first refrigeration device 8 and an upper circulation fan 35 that supplies air to the evaporator 15 and forms an airflow that circulates in the upper region of the storage chamber 4. The lower heat exchange chamber 40 is provided with an evaporator 22 of the second refrigeration device 9 and a lower circulation fan 45 that supplies air to the evaporator 22 and forms an airflow that circulates in the lower region of the storage chamber 4.

[0007] The refrigeration capacity of the two refrigeration systems 8 and 9 is configured such that the first refrigeration system 8 has a relatively larger refrigeration capacity, while the second refrigeration system 9 has a relatively smaller one. In the second refrigeration system 9, the compressor 19, condenser 20, capillary tube 21 constituting the expansion section, and evaporator 22 are connected in a loop shape by connecting piping 23 in the order described. The return pipe 23a of the connecting piping 23 leading from the evaporator 22 to the compressor 19 and the capillary tube 21 are arranged in the storage chamber 4 in a state where heat exchange is possible.

[0008] The upper heat exchange chamber 33 is provided along the top surface 4a of the storage chamber 4, and the lower heat exchange chamber 40 is provided along the back surface 4b of the storage chamber 4. An air intake port 36 for drawing air into the upper heat exchange chamber 33 is provided at the lower front end of the upper heat exchange chamber 33, and an air outlet 37 for blowing air downward from the upper heat exchange chamber 33 toward the back surface 4b of the storage chamber 4 is provided at the lower rear end of the upper heat exchange chamber 33. The return pipe 23a and the capillary tube 21 are arranged along the back surface 4b of the upper half of the storage chamber 4.

[0009] The return pipe 23a and capillary tube 21, located inside the storage chamber 4, are covered by the back surface 4b of the storage chamber 4 and a pipe cover 53 fixed to the back surface 4b. [Effects of the Invention]

[0010] In the cooler according to the present invention, an evaporator 15 of the first refrigeration unit 8 and an upper circulation fan 35 that supplies air to the evaporator 15 and forms an airflow that circulates in the upper part of the storage chamber 4 are provided in an upper heat exchange chamber 33 partitioned in the upper half of the storage chamber 4. An evaporator 22 of the second refrigeration unit 9 and a lower circulation fan 45 that supplies air to the evaporator 22 and forms an airflow that circulates in the lower part of the storage chamber 4 are provided in a lower heat exchange chamber 40 partitioned in the lower half of the storage chamber 4. As a result, the air in the storage chamber 4 directly exchanges heat with the evaporator 15 located in the upper half of the storage chamber 4 and with the evaporator 22 located in the lower half of the storage chamber 4. This prevents a decrease in heat exchange efficiency, unlike conventional coolers where heat exchange between the air and the evaporator is indirect in the lower half of the storage chamber. Furthermore, by forming airflows that circulate in the upper and lower regions of the storage chamber 4 using the upper and lower circulation fans 35 and 45, the air in the storage chamber 4 can be sufficiently stirred, preventing temperature unevenness. Thus, according to the cooler of the present invention, the storage chamber 4 can be efficiently cooled by the two refrigeration systems 8 and 9 while preventing temperature unevenness and ensuring a uniform temperature within the storage chamber 4.

[0011] If the cooling capacities of the two refrigeration units 8 and 9 are configured such that the first refrigeration unit 8 is relatively larger and the second refrigeration unit 9 is relatively smaller, it is possible to prevent a temperature difference from occurring between the upper and lower parts of the storage chamber 4. Specifically, even if the air in the storage chamber 4 is agitated by the upper and lower circulation fans 35 and 45, the cold air tends to accumulate in the lower part of the storage chamber 4, and the temperature in the lower part of the storage chamber 4 tends to be lower than the temperature in the upper part of the storage chamber 4. Therefore, by configuring the cooling capacity of the second refrigeration unit 9 to be smaller than that of the first refrigeration unit 8, as in the present invention, the degree of cooling in the lower half of the storage chamber 4 can be suppressed compared to the upper half of the storage chamber 4, and the temperature difference of the air after it has been cooled by both evaporators 15 and 22 can be reduced, thus preventing a temperature difference from occurring between the upper and lower parts of the storage chamber 4.

[0012] If the return pipe 23a of the connecting piping 23 from the evaporator 22 to the compressor 19 of the second refrigeration unit 9 and the capillary tube 21 are arranged in the storage chamber 4 in a heat exchangeable state, the low-temperature gaseous refrigerant flowing through the return pipe 23a can cool the high-temperature liquid refrigerant flowing through the capillary tube 21. Furthermore, the air in the storage chamber 4 can cool the capillary tube 21, further reducing the temperature of the high-temperature liquid refrigerant flowing through it. In this way, by cooling the high-temperature liquid refrigerant flowing through the capillary tube 21, the temperature of the liquid refrigerant supplied to the evaporator 22 can be lowered, allowing the evaporator 22 to be cooled to a lower temperature. As a result, the air in the lower half of the storage chamber 4 can be cooled to the same level as the air in the upper half, even with the second refrigeration unit 9 which has a smaller refrigeration capacity, thus reducing the overall cost and running costs of the refrigeration unit.

[0013] An air intake port 36 for taking air into the upper heat exchange chamber 33 is provided at the lower front end of the upper heat exchange chamber 33, which is located along the top surface 4a of the storage chamber 4, and an air outlet 37 for blowing air downward from the upper heat exchange chamber 33 toward the back surface 4b of the storage chamber 4 is provided at the lower rear end of the upper heat exchange chamber 33, and the return pipe 23a and capillary tube 21 are arranged along the back surface 4b of the upper half of the storage chamber 4, so that air that has just been cooled by heat exchange with the evaporator 15 of the first refrigeration device 8 is blown onto the return pipe 23a and capillary tube 21, thereby lowering the temperature of the liquid refrigerant flowing through the return pipe 23a, and thus further lowering the temperature of the liquid refrigerant supplied to the evaporator 22.

[0014] If the return pipe 23a and capillary tube 21, which are located inside the storage chamber 4, are covered by the back surface 4b of the storage chamber 4 and a pipe cover 53 fixed to the back surface 4b, then damage to articles stored in the storage chamber 4 due to contact with the return pipe 23a and capillary tube 21 can be effectively prevented. [Brief explanation of the drawing]

[0015] [Figure 1] This is a longitudinal cross-sectional side view of a cooling chamber according to an embodiment of the present invention. [Figure 2]This is a circuit diagram of a refrigeration system. [Figure 3] This is a longitudinal cross-sectional side view showing the upper part of the cooler, including the upper heat exchange chamber. [Figure 4] This is a partially cutaway front view showing the lower part of the cooler, including the lower heat exchange chamber. [Modes for carrying out the invention]

[0016] (Embodiment) Figures 1 to 4 show an embodiment of the cooler according to the present invention. In this embodiment, front, back, left, right, and up and down refer to the intersecting arrows shown in Figures 1 and 4 and the front, back, left, right, and up and down indications written near each arrow. The cooler according to this embodiment is a sealed commercial freezer (hereinafter simply referred to as a freezer), and as shown in Figure 1, the freezer comprises a storage body 1 consisting of a vertically elongated insulated rectangular box with a front opening, a swing-type door 2 that opens and closes the front opening, and a machine room 3 provided above the storage body 1, with a vertically elongated storage chamber 4 defined inside the storage body 1. The front opening of the storage body 1 is divided into an upper opening 6 and a lower opening 7 by an intermediate frame 5 horizontally installed on the edge of the opening. Doors 2 are provided for each of the openings 6 and 7, respectively, and by opening the door 2, the upper half of the storage chamber 4 can be accessed through opening 6, and by opening the door 2, the lower half of the storage chamber 4 can be accessed through opening 7. The storage chamber 4 is cooled by two independent cooling systems: the first refrigeration unit 8 and the second refrigeration unit 9.

[0017] As shown in Figure 2, the first refrigeration unit 8 includes a compressor 12 for compressing gaseous refrigerant, a condenser 13 for liquefying the high-pressure gaseous refrigerant discharged from the compressor 12, a capillary tube 14 which constitutes an expansion section that reduces the pressure of the high-pressure liquid refrigerant discharged from the condenser 13 and causes adiabatic expansion, and an evaporator 15 for evaporating the low-pressure liquid refrigerant discharged from the capillary tube 14. The compressor 12, condenser 13, capillary tube 14, and evaporator 15 are connected by connecting pipes 16 in the order described, and a loop-shaped refrigerant circuit is constructed by these devices 12-15 and the connecting pipes 16.

[0018] The second refrigeration unit 9 includes a compressor 19 for compressing gaseous refrigerant, a condenser 20 for liquefying the high-pressure gaseous refrigerant discharged from the compressor 19, a capillary tube 21 which constitutes an expansion section that reduces the pressure of the high-pressure liquid refrigerant discharged from the condenser 20 and causes adiabatic expansion, and an evaporator 22 for evaporating the low-pressure liquid refrigerant discharged from the capillary tube 21. The compressor 19, condenser 20, capillary tube 21, and evaporator 22 are connected by connecting pipes 23 in the order described, and a loop-shaped refrigerant circuit is constructed by these devices 19-22 and the connecting pipes 23.

[0019] As shown in Figure 3, the machine room 3 houses the compressor 12 and condenser 13 of the first refrigeration unit 8, and the compressor 19 and condenser 20 of the second refrigeration unit 9. Each of these devices is fixed to the upper surface of the unit base 25, and the evaporator 15 of the first refrigeration unit 8 is fixed to the lower surface of the base 25. A through-hole 26 is provided in the top wall 1a of the storage unit 1, allowing the storage unit 1 to communicate with the inside and outside, and the unit base 25 is fixed to the upper surface of the top wall 1a of the storage unit 1 so as to close the communication hole 26. The unit base 25 and the devices fixed to the upper and lower surfaces of the base 25 are unitized, and by fixing the unit base 25 to the upper surface of the top wall 1a, both compressors 12 and 19 and both condensers 13 and 20 are installed in the machine room 3, and the evaporator 15 of the first refrigeration unit 8 is installed in the upper part of the storage room 4.

[0020] In this embodiment, the condenser 13 of the first refrigeration device 8 and the condenser 20 of the second refrigeration device 9 are integrally formed and configured as a single integrated condenser 27. The upper half of the integrated condenser 27 is the condenser 13, and the lower half is the condenser 20. The integrated condenser 27 is disposed within a duct 28 having openings at the front and rear. At the rear opening of the duct 28, a cooling fan 29 for generating an air flow for heat exchange passing through the integrated condenser 27 is provided. When the cooling fan 29 is driven, the air in the front of the machine room 3 is taken into the duct 28. After the air air-cools the integrated condenser 27, it is blown out rearward from the duct 28. Subsequently, the air blown out from the duct 28 is fed to the compressor 12 of the first refrigeration device 8 and the compressor 19 of the second refrigeration device 9 to air-cool both compressors 12 and 19. Between the cooling fan 29 and both compressors 12 and 19, a feed guide 30 for diverting the air blown out from the duct 28 to each compressor 12 and 19 is provided. The feed guide 30 is formed in a V shape in plan view (see FIG. 2).

[0021] As shown in FIG. 3, an upper heat exchange chamber 33 provided along the top surface 4a is provided in the upper half of the storage chamber 4. Specifically, the top surface 4a of the storage chamber 4 is formed by the lower surface of the top wall 1a of the storage body 1 and the lower surface of the unit base 25. Below the top surface 4a, an evaporator cover 34 formed of a substantially horizontal wall is fixed in a state facing the communication port 26. The region sandwiched between the top surface 4a of the storage chamber 4 and the evaporator cover 34 is partitioned as the upper heat exchange chamber 33. The evaporator 15 of the first refrigeration device 8 fixed to the lower surface of the unit base 25 is disposed in the upper heat exchange chamber 33. In the upper heat exchange chamber 33, in addition to the evaporator 15 of the first refrigeration device 8, an upper circulation fan 35 for feeding air to the evaporator 15 and forming an air flow circulating in the upper half of the storage chamber 4 (the upper region of the storage chamber 4) is provided.

[0022] On the lower side of the front end of the upper heat exchange chamber 33, an air intake port 36 for taking air into the upper heat exchange chamber 33 is provided. The air intake port 36 is composed of round holes formed in a penetrating manner in the front part of the evaporator cover 34. Further, on the lower side of the rear end of the upper heat exchange chamber 33, an air outlet 37 for blowing air downward from the upper heat exchange chamber 33 is provided. The air outlet 37 is composed of a gap extending in the left - right direction formed between the rear - end edge of the evaporator cover 34 and the inner surface 4b of the storage body 1. The previous upper circulation fan 35 is fixed facing the air intake port 36. When the upper circulation fan 35 is driven, the air in the storage chamber 4 is taken into the upper heat exchange chamber 33 through the air intake port 36 and fed to the evaporator 15. The air is heat - exchanged and cooled by the evaporator 15 and then blown out from the air outlet 37. At this time, the air blown out from the air outlet 37 is blown downward toward the inner surface 4b of the storage chamber 4. The air blown along the inner surface 4b is redirected forward by the air flow formed by the lower circulation fan 45 described later on the lower side of the upper half of the storage chamber 4. Subsequently, the air redirected forward is redirected upward on the back surface of the door 2 and reaches the air intake port 36. As described above, in the upper half of the storage chamber 4, an air flow circulating clockwise in FIG. 1 is formed by the upper circulation fan 35.

[0023] In the lower half of the storage chamber 4, a lower heat exchange chamber 40 is provided along the inner surface 4b of the storage chamber. Specifically, on the inner surface 4b of the storage chamber 4 in the lower half of the storage chamber 4, a duct body 41 composed of a flat square box body opening backward is fixed. The region surrounded by the duct body 41 and the inner surface 4b of the storage chamber 4 is partitioned as the lower heat exchange chamber 40. The duct body 41 includes a square - plate - shaped duct main wall 42 parallel to the inner surface 4b of the storage chamber 4, a square - frame - shaped duct peripheral wall 43 extending backward from the upper, lower, left, and right peripheral edges of the duct main wall 42, and fixing pieces 44 extending outward from the left and right duct peripheral walls 43. By fastening the fixing pieces 44 to the rear wall 1b of the storage body 1 with screws (not shown), the duct body 41 is fixed to the inner surface 4b of the storage chamber 4. In the lower heat exchange chamber 40, an evaporator 22 of the second refrigeration device 9 and a lower circulation fan 45 for feeding air to the evaporator 22 and forming an air flow circulating in the lower half of the storage chamber 4 (the lower region of the storage chamber 4) are provided.

[0024] At the bottom of the lower heat exchange chamber 40, an air intake port 46 is provided to draw air into the lower heat exchange chamber 40, and this air intake port 46 consists of a group of elongated holes opened in the main wall 42 of the duct. At the top of the lower heat exchange chamber 40, an air outlet 47 is provided to blow air forward from the lower heat exchange chamber 40, and this air outlet 47 consists of a round hole formed through the main wall 42 of the duct. The evaporator 22 of the second refrigeration unit 9 is positioned in the lower heat exchange chamber 40 between the air intake port 46 and the air outlet 47, and the lower circulation fan 45 is fixed facing the air outlet 47.

[0025] When the lower circulation fan 45 is driven, air from the storage chamber 4 is drawn into the lower heat exchange chamber 40 via the air intake 46 and supplied to the evaporator 22. This air is then cooled by heat exchange in the evaporator 22 and then blown forward from the outlet 47. Subsequently, the air blown out from the outlet 47 is redirected downward on the back of the door 2, and further redirected backward at the bottom wall of the storage body 1 before reaching the air intake 46. Thus, in the lower half of the storage chamber 4, the lower circulation fan 45 creates an airflow that circulates counterclockwise in Figure 1. The air blown downward from the outlet 37 by the upper circulation fan 35 is redirected forward by the air blown forward from the outlet 47 by the lower circulation fan 45, so that both the upper and lower airflows flow forward, and in the process, a portion of both airflows mix, promoting the homogenization of the air temperature.

[0026] The cooling capacities of the two refrigeration units 8 and 9 are configured such that the first refrigeration unit 8 has a relatively larger cooling capacity, while the second refrigeration unit 9 has a relatively smaller one. Specifically, even though the air in the storage chamber 4 is agitated by the upper and lower circulation fans 35 and 45, the cold air tends to accumulate at the bottom of the storage chamber 4, resulting in a lower temperature at the bottom of the storage chamber 4 compared to the temperature at the top. Therefore, the temperature of the air taken in at the intake port 45 of the lower heat exchange chamber 40 (the temperature of the air just before passing through the evaporator 22) tends to be lower than the temperature of the air taken in at the intake port 36 of the upper heat exchange chamber 33 (the temperature of the air just before passing through the evaporator 15). This is because the degree of cooling required to bring the temperature of the air after heat exchange by the evaporator 15 in the upper heat exchange chamber 33 and the temperature of the air after heat exchange by the evaporator 22 in the lower heat exchange chamber 40 to the same temperature is different.

[0027] As shown in Figure 2, in the first refrigeration system 8, the connecting pipe 16 from the evaporator 15 to the compressor 12 is a return pipe 16a through which both the low-temperature gaseous refrigerant vaporized in the evaporator 15 and the low-temperature liquid refrigerant that did not vaporize in the evaporator 15 flow. The middle section of this return pipe 16a and the middle section of the capillary tube 14 through which the high-temperature liquid refrigerant flows are arranged parallel to each other with the pipe bodies constituting them in close contact, forming a heat transfer section 49, and the return pipe 16a and the capillary tube 14 are configured to exchange heat. The heat transfer section 49 is located in the machine room 3.

[0028] Similarly, in the second refrigeration unit 9, the connecting pipe 23 from the evaporator 22 to the compressor 19 is a return pipe 23a through which low-temperature liquid refrigerant that did not vaporize in the evaporator 22 flows along with the low-temperature gaseous refrigerant vaporized in the evaporator 22. The middle section of this return pipe 23a and the middle section of the capillary tube 21 through which high-temperature liquid refrigerant flows are arranged in parallel with the pipe bodies constituting them in close contact, forming a heat transfer section 50, and the return pipe 23a and the capillary tube 21 are configured to exchange heat.

[0029] As described above, if a heat transfer section 49(50) is provided that enables heat exchange between the return pipe 16a(23a) and the capillary tube 14(21), the high-temperature liquid refrigerant flowing through the capillary tube 14(21) can be cooled by the low-temperature gaseous refrigerant flowing through the return pipe 16a(23a), thereby improving the refrigeration capacity by supplying low-temperature liquid refrigerant through the evaporator 15(22). Furthermore, if a heat transfer section 49(50) is provided, the low-temperature gaseous refrigerant flowing through the return pipe 16a(23a) can be heated by the high-temperature liquid refrigerant flowing through the capillary tube 14(21), allowing any liquid refrigerant that has not completely evaporated in the evaporator 15(22) to be vaporized in the heat transfer section 49(50).

[0030] The heat transfer section 50 of the second refrigeration unit 9 is located in the storage chamber 4. Specifically, as shown in Figure 4, the return pipe 23a is routed out from the lower left side of the evaporator 22 and is arranged to extend upward. The capillary tube 21 is routed out from the upper left side of the evaporator 22 and is connected to the refrigerant inlet pipe 51. These capillary tubes 21 and the return pipe 23a are arranged in close contact front to back to form the heat transfer section 50. This heat transfer section 50 is housed within the wall of the storage unit 1 at the upper end of the rear wall 1b of the storage unit 1 and is routed out from the upper surface of the top wall 1a of the storage unit 1 to the machine room 3 (see Figure 3). The capillary tube 21 is separated from the return pipe 23a at the point where it is routed to the machine room 3. Based on the above, the heat transfer section 50 (return pipe 23a and capillary tube 21) is positioned along the back surface 4b of the upper half of the storage chamber 4 through which the air blown out from the outlet 37 of the upper heat exchange chamber 33 flows.

[0031] The return pipe 23a and the refrigerant inlet pipe 51 are led out to the outside of the lower heat exchange chamber 40 from an outlet 52 that opens at the upper left end of the duct peripheral wall 43 of the duct body 41. Most of the capillary tube 21, including the return pipe 23a and the refrigerant inlet pipe 51 which are arranged above the outlet 52, is covered by the back surface 4b of the storage chamber 4 and a pipe cover 53 fixed to the back surface 4b. The pipe cover 53 comprises a vertically elongated plate-shaped main cover wall 54 parallel to the back surface 4b of the storage chamber 4, a cover peripheral wall 55 consisting of a three-sided frame-shaped frame extending backward from the top and left and right periphery of the main cover wall 54, and fixing pieces 56 extending outward from the left and right cover peripheral walls 55. The pipe cover 53 is fixed to the back surface 4b of the storage chamber 4 by fastening the fixing pieces 56 to the rear wall 1b of the storage body 1 with screws (not shown).

[0032] The main cover wall 54 is widened at its lower end, and the lower end opening formed by the main cover wall 54 and the left and right cover peripheral walls 55 is shaped to match the outlet 52 of the duct body 41. The outlet 52 formed in the upper duct peripheral wall 43 that partitions the lower heat exchange chamber 40 is closed at the lower end of the pipe cover 53. The upper cover peripheral wall 55 has a notch 57 for guiding out the return pipe 23a and the capillary tube 21 (heat transfer section 50). Some of the air blown out from the outlet 37 enters the inside of the pipe cover 53 through the upper notch 57, and heat is conducted to the inside and outside of the pipe cover 53 via the main cover wall 54 and the cover peripheral walls 55, so the air temperature inside and outside the pipe cover 53 does not differ significantly.

[0033] As described above, in the freezer of this embodiment, the upper heat exchange chamber 33 partitioned in the upper half of the storage chamber 4 is equipped with the evaporator 15 of the first refrigeration unit 8 and the upper circulation fan 35 which supplies air to the evaporator 15 and forms an airflow that circulates in the upper region of the storage chamber 4. The lower heat exchange chamber 40 partitioned in the lower half of the storage chamber 4 is equipped with the evaporator 22 of the second refrigeration unit 9 and the lower circulation fan 45 which supplies air to the evaporator 22 and forms an airflow that circulates in the lower region of the storage chamber 4. With this configuration, the air in the storage chamber 4 directly exchanges heat with the evaporator 15 located in the upper half of the storage chamber 4 and with the evaporator 22 located in the lower half of the storage chamber 4. This prevents a decrease in heat exchange efficiency, unlike conventional coolers where heat exchange between the air and the evaporator is indirect in the lower half of the storage chamber. Furthermore, by forming airflows that circulate in the upper and lower regions of the storage chamber 4 using the upper and lower circulation fans 35 and 45, the air in the storage chamber 4 can be sufficiently stirred, preventing temperature unevenness. Thus, according to the cooler of this embodiment, the storage chamber 4 can be efficiently cooled by the two refrigeration systems 8 and 9 while preventing temperature unevenness and ensuring a uniform temperature within the storage chamber 4.

[0034] By configuring the cooling capacity of both refrigeration units 8 and 9 so that the first refrigeration unit 8 is relatively larger and the second refrigeration unit 9 is relatively smaller, it is possible to prevent a temperature difference from occurring between the upper and lower parts of the storage chamber 4. Specifically, even though the air in the storage chamber 4 is agitated by the upper and lower circulation fans 35 and 45, the cold air tends to accumulate in the lower part of the storage chamber 4, and the temperature in the lower part of the storage chamber 4 tends to be lower than the temperature in the upper part of the storage chamber 4. Therefore, by configuring the cooling capacity of the first refrigeration unit 8 to be relatively larger and the cooling capacity of the second refrigeration unit 9 to be relatively smaller, as in this embodiment, the degree of cooling in the lower half of the storage chamber 4 can be suppressed compared to the upper half of the storage chamber 4, and the temperature difference of the air after it has been cooled by both evaporators 15 and 22 can be reduced, thus preventing a temperature difference from occurring between the upper and lower parts of the storage chamber 4.

[0035] In addition to the above, the return pipe 23a and capillary tube 21 of the connecting pipe 23 from the evaporator 22 to the compressor 19 of the second refrigeration unit 9 are arranged in the storage chamber 4 in a heat exchangeable state. This allows the low-temperature gaseous refrigerant flowing through the return pipe 23a to cool the high-temperature liquid refrigerant flowing through the capillary tube 21. Furthermore, the air in the storage chamber 4 can cool the capillary tube 21, further reducing the temperature of the high-temperature liquid refrigerant flowing through it. By cooling the high-temperature liquid refrigerant flowing through the capillary tube 21 in this way, the temperature of the liquid refrigerant supplied to the evaporator 22 can be lowered, allowing the evaporator 22 to be cooled to a lower temperature. As a result, the second refrigeration unit 9, which has a smaller refrigeration capacity, can cool the air in the lower half of the storage chamber 4 to the same level as the air in the upper half, thereby reducing the overall cost and running costs of the refrigeration unit.

[0036] An air intake port 36 is provided at the lower front end of the upper heat exchange chamber 33, which is located along the top surface 4a of the storage chamber 4, to draw air into the upper heat exchange chamber 33. An air outlet 37 is provided at the lower rear end of the upper heat exchange chamber 33 to blow air downward from the upper heat exchange chamber 33 along the back surface 4b of the storage chamber 4. Furthermore, since the return pipe 23a and the capillary tube 21 are arranged along the back surface 4b of the upper half of the storage chamber 4, it is possible to blow the air that has just been cooled by heat exchange with the evaporator 15 of the first refrigeration device 8 onto the return pipe 23a and the capillary tube 21, thereby cooling the liquid refrigerant flowing through the return pipe 23a and further lowering the temperature of the liquid refrigerant supplied to the evaporator 22.

[0037] The return pipe 23a and capillary tube 21, which are located inside the storage chamber 4, are covered by the back surface 4b of the storage chamber 4 and a pipe cover 53 fixed to the back surface 4b. This effectively prevents damage to articles stored in the storage chamber 4 due to contact with the return pipe 23a and capillary tube 21.

[0038] The pipe cover 53 described above has a main cover wall 54 and a cover peripheral wall 55 formed in a plate shape, but multiple openings may be provided in each wall 54 and 55 to allow air to circulate inside and outside through the pipe cover 53. The present invention can be applied not only to commercial freezers but also to commercial refrigerators and reach-in type display cases. [Explanation of Symbols]

[0039] 1. Main body of the storage unit 4 Storage Rooms 4a Top surface of the storage room 4b Back of the storage room 8. First Refrigeration Unit 9. Second Refrigeration Unit 15 Evaporator 19 Compressor 20 Condenser 21 Capillary tube 22 Evaporator 23 Connecting pipes 23a Return tube 33 Upper heat exchange chamber 35 Upper circulation fan 36 Air intake 37 Air outlet 40 Lower heat exchange room 45 Lower circulation fan 53 Pipe cover

Claims

1. The storage unit comprises a main body (1) with a storage chamber (4) defined inside, and a first refrigeration device (8) and a second refrigeration device (9) for cooling the storage chamber (4). The storage chamber (4) is divided into an upper heat exchange chamber (33) in the upper half and a lower heat exchange chamber (40) in the lower half. A cooler characterized in that an upper heat exchange chamber (33) is provided with an evaporator (15) of a first refrigeration unit (8) and an upper circulation fan (35) that supplies air to the evaporator (15) and forms an airflow that circulates in the upper region of the storage chamber (4), and a lower heat exchange chamber (40) is provided with an evaporator (22) of a second refrigeration unit (9) and a lower circulation fan (45) that supplies air to the evaporator (22) and forms an airflow that circulates in the lower region of the storage chamber (4).

2. The cooling capacity of the two refrigeration systems (8 and 9) is configured such that the first refrigeration system (8) has a relatively larger cooling capacity, while the second refrigeration system (9) has a relatively smaller cooling capacity. The second refrigeration unit (9) has a compressor (19), a condenser (20), a capillary tube (21) that constitutes the expansion section, and an evaporator (22) connected in a loop shape by connecting pipes (23) in the order described above. The cooler according to claim 1, wherein the return pipe (23a) of the connecting pipe (23) leading from the evaporator (22) to the compressor (19) and the capillary tube (21) are arranged in the storage chamber (4) in a manner that allows for heat exchange.

3. The upper heat exchange chamber (33) is provided along the top surface (4a) of the storage chamber (4), and the lower heat exchange chamber (40) is provided along the back surface (4b) of the storage chamber (4). An air intake port (36) for drawing air into the upper heat exchange chamber (33) is provided at the lower front end of the upper heat exchange chamber (33), and an air outlet (37) for blowing air downward from the upper heat exchange chamber (33) toward the back surface (4b) of the storage chamber (4) is provided at the lower rear end of the upper heat exchange chamber (33). The cooler according to claim 2, wherein the return pipe (23a) and the capillary tube (21) are arranged along the back surface (4b) of the upper half of the storage chamber (4).

4. The cooler according to claim 2, wherein the return pipe (23a) and capillary tube (21) located inside the storage chamber (4) are covered by the back surface (4b) of the storage chamber (4) and a pipe cover (53) fixed to the back surface (4b).

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