Cooling device

Abstract

To provide a cooling device that can effectively prevent a combustible refrigerant from remaining when the combustible refrigerant leaks.SOLUTION: A cooling device is provided with a compressor, a condenser and a cooling fan for cooling the condenser in a machine room allowing air to circulate, and furthermore, an evaporator in a cooling space partitioned from the machine room. Thereby, the device is configured to: perform cooling operation by compressing a combustible refrigerant by the compressor; and operate the cooling fan in a state of stopping the operation of the compressor so that rotational speed is lower than that in operation of the compressor, and variably controls the cooling fan so as to change the rotational speed of the cooling fan in accordance with the operation state of the compressor.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cooling device, and more particularly to a cooling device that includes a compressor, a condenser, and a cooling fan for cooling the condenser, and uses a flammable refrigerant as the refrigerant.

Background Art

[0002] Cooling devices such as refrigerators and ice makers, which are preferably used in kitchen facilities such as tea houses and restaurants, include a cooling device composed of a compressor, a condenser, and a cooler. The high-pressure gaseous refrigerant supplied from the compressor is cooled (heat-exchanged) in the condenser and condensed and liquefied, and the cooler is cooled by utilizing the heat of vaporization when the condensed and liquefied refrigerant vaporizes. Further, a cooling fan for the condenser is disposed at a position close to the condenser, and by operating the cooling fan, external air is taken into the machine room to air-cool the condenser, so that the refrigerant is efficiently condensed and liquefied. In addition, as a refrigerant used in such a cooling device, instead of a fluorocarbon gas or an alternative fluorocarbon with a high environmental load, a flammable refrigerant such as a hydrocarbon (HC-based) such as butane or propane, which has excellent characteristics as a refrigerant such as heat of vaporization and saturation pressure, is used to reduce the environmental load (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in configurations that utilize flammable refrigerants, there is a possibility that flammable refrigerant may leak if the refrigerant piping is damaged due to aging or some external factor. For this reason, Patent Document 1 describes positioning the cooling fan furthest upwind relative to the airflow of the cooling fan within the machine room. However, even when the cooling fan is positioned furthest upwind, there is concern that leaked flammable refrigerant may accumulate locally within the machine room.

[0005] Therefore, the present invention has been proposed to suitably solve the aforementioned problems inherent in the prior art, and aims to provide a cooling device that can effectively prevent the accumulation of flammable refrigerant in the event of a leak. [Means for solving the problem]

[0006] In order to overcome the aforementioned challenges and achieve the intended objectives, the first means teeth, In a cooling system in which a compressor (32), a condenser (34), and a cooling fan (36) for cooling the condenser (34) are provided in an open space (20) where air circulation is permitted, and a cooler (38) is provided in a cooling space partitioned from the open space (20), and a flammable refrigerant is used as the refrigerant compressed by the compressor (32), The gist of the configuration is that the cooling fan (36) is configured to be variably controlled so as to change the rotational speed of the cooling fan (36) according to the operating state of the compressor (32). child re According to the report, by varying the rotation speed of the cooling fan according to the operating state of the compressor, even if corrosion occurs and holes (pitting) develop, causing flammable refrigerant to leak, the cooling air generated by the cooling fan can expel the leaked flammable refrigerant from the machine, preventing it from accumulating.

[0007] Second means teeth, The gist of this invention is that the cooling fan (36) is configured to operate at a lower rotational speed than when the compressor (32) is operating, even when the compressor (32) is stopped. child re According to the research, when the compressor is stopped, rotating the cooling fan at a lower speed than when the compressor is running can reduce power consumption compared to continuously rotating the cooling fan at a constant speed, while also preventing the accumulation of flammable refrigerant.

[0008] The third means teeth, The gist of this configuration is that the rotational speed of the cooling fan (36) is variable when the operation of the compressor (32) is stopped. child re According to this, by varying the rotation speed of the cooling fan, it is possible to change the state of the air (wind conditions) flowing through the area where the compressor is located, even when the compressor is stopped, thereby more effectively preventing the accumulation of flammable refrigerant.

[0009] The fourth means teeth, The gist of the configuration is that the cooling fan (36) is operated intermittently while the compressor (32) is stopped. child re According to the research, simply by controlling the cooling fan on and off, it is possible to vary the rotation speed of the cooling fan while the compressor is stopped, which has the advantage of preventing the accumulation of flammable refrigerant. [Effects of the Invention]

[0010] According to the cooling device of the present invention, it is possible to effectively prevent the accumulation of flammable refrigerant in the event of a leak. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic side view showing a refrigerator according to Embodiment 1, partially cut away. [Figure 2]This is a block diagram showing the main components of the refrigerator's control system. [Figure 3] This is an explanatory diagram showing the relationship between the operation of the compressor and the cooling fan in the cooling device according to Embodiment 1. [Figure 4] This is an explanatory diagram showing the relationship between the operation of the compressor and the cooling fan in the cooling device according to Embodiment 2. [Figure 5] This is an explanatory diagram showing the relationship between the operation of the compressor and the cooling fan in the cooling device according to Embodiment 3. [Modes for carrying out the invention]

[0012] Next, preferred embodiments of the cooling device according to the present invention will be described below with reference to the attached drawings. The description will use a cooling device installed in a refrigerator used for commercial purposes such as a store, capable of storing items such as vegetables and meat, as an example.

[0013] (Embodiment 1) As shown in FIG. 1, the refrigerator 10 according to Embodiment 1 includes a box body 12 having a heat-insulating structure that internally defines a storage chamber (closed space) 14, and a cabinet 16 provided above the box body 12 and having an outer wall formed of a metal panel 18 or the like. An opening 12a that is open at the front side and serves as an access opening for articles communicates with the storage chamber 14 and is provided in the box body 12. Further, a heat-insulating door 22 is disposed at the front portion of the box body 12 so as to be rotatable by a hinge not shown. By opening the heat-insulating door 22, access to the storage chamber 14 through the opening 12a is permitted for articles, and by closing the heat-insulating door 22, the storage chamber 14 can be sealed. A machine room (open space) 20 is defined inside the cabinet 16, and a part of a cooling device 30 for cooling the storage chamber 14 and a control device 50 for controlling the cooling device 30 are disposed on a bottom plate 20a that forms the bottom of the machine room 20. The cabinet 16 is formed in a box shape with the upper part of the machine room 20 open, and air circulation holes (not shown) are provided at appropriate positions such as a front panel 24a and a rear panel 24b that form the front surface of the cabinet 16, so that air can circulate inside and outside the machine room 20. A cooling duct 29 that defines a cooling chamber 28 in which an evaporator (cooler) 38 and an internal fan 26 are stored and communicates with the storage chamber 14 is provided above the box body 12. By operating the internal fan 26, the cold air cooled by the evaporator 38 is circulated to the storage chamber 14 for cooling.

[0014] The cooling device 30 disposed on the bottom plate 20a that forms the machine room 20 in the cabinet 16 includes a compressor 32 that compresses a refrigerant, a condenser 34 that condenses and liquefies the compressed vaporized refrigerant, a cooling fan 36 for cooling the condenser 34, etc. The condenser 34, the cooling fan 36, and the compressor 32 are arranged in this order from the front side of the machine room 20. And a refrigerant pipe (not shown) led out from the compressor 32 is connected to the condenser 34, a refrigerant pipe led out from the condenser 34 is connected to the evaporator 38 via a capillary tube or the like not shown, and a refrigerant pipe led out from the evaporator 38 is connected to the compressor 32, and is configured to form a refrigeration circuit. Thus, by rotating the cooling fan 36, external air is sucked into the machine room 20 through the air circulation holes formed in the front panel 24a to air-cool the condenser 34 and the compressor 32. And the air that has exchanged heat with the condenser 34 and the compressor 32 and has risen in temperature is discharged to the outside through the air circulation holes formed in the rear panel 24b that defines the rear side of the machine room 20 in the cabinet 16 and the opening at the upper part of the machine room 20. That is, when the cooling fan 36 rotates (operates), the air is configured to flow from the front side to the rear side.

[0015] The cooling fan 36 includes a rotating blade 36a and a drive motor 36b that rotationally drives the rotating blade 36a, and the cooling fan is disposed on the rear side of the condenser 34. Also, on the bottom plate 20a of the machine room 20, a shroud (wind tunnel) 42 for rectifying the wind generated by the rotation of the cooling fan 36 to efficiently air-cool the condenser 34 is provided, and the shroud 424 is configured to surround the condenser 34 and open in the front-rear direction. Here, in the present embodiment, as the drive motor 36b of the cooling fan 36, a variable speed motor such as a servo motor whose rotation speed can be variably controlled is used. Also, as shown in FIG. 2, in the refrigerator 10 of the present embodiment, temperature detection means for detecting the temperature of the cooling chamber 28 (storage chamber 14) 44 is connected to the control device 50 to which the compressor 32 and the cooling fan 36 (drive motor 36b) are connected.

[0016] As shown in Figure 3, the compressor 32 is controlled by the control means 22 so that when the temperature detection means 44 detects a preset lower limit temperature, the compressor 32 stops operating (cooling operation stops). Furthermore, when the cooling operation stops, the temperature of the storage chamber 14 rises, and the temperature detection means 44 detects a preset upper limit temperature, the compressor 32 is controlled by the control means 22 so that the compressor 32 restarts operating. In other words, the cooling device 30 is controlled by the control means 22 to repeatedly operate and stop according to the temperature detected by the temperature detection means 44, thereby maintaining the temperature of the storage chamber 14 within a predetermined temperature range.

[0017] Here, a minimum stop time is set for maintaining the stopped state of the compressor 32 when the temperature detection means 44 detects a lower limit temperature and stops the compressor 32. Until the minimum stop time has elapsed, the compressor 32 will remain stopped even if the temperature detection means 44 detects an upper limit temperature. In this way, after the cooling operation is completed, the compressor 32 is stopped for a period of time longer than the minimum stop time to stabilize the state of the refrigerant in the refrigeration circuit and suppress the load when the cooling operation is restarted.

[0018] Furthermore, as shown in Figure 3, the control device 50 is configured to variably control the rotational speed of the cooling fan 36 (drive motor 36b) so that the rotational speed of the cooling fan 36 changes according to the operating state of the compressor 32. Specifically, the cooling device 30 of Embodiment 1 is configured such that when the compressor 32 is operating (when cooling operation is being performed), the control device 50 controls the cooling fan 36 to rotate at a first rotational speed, and when the compressor 32 is stopped, the control device 50 controls the cooling fan 36 to rotate at a second rotational speed lower than the first rotational speed. In other words, the rotational speed of the cooling fan 36 is switched from the first rotational speed to a lower second rotational speed when the temperature detection means 44 detects a lower limit temperature, and the rotational speed of the cooling fan 36 is switched to a first rotational speed higher than the second rotational speed when the temperature detection means 44 detects an upper limit temperature.

[0019] In this way, by continuing to operate the cooling fan 36 even when the compressor 32 is stopped, even if corrosion occurs and holes (pitting) develop in the refrigerant pipe 40, causing flammable refrigerant to leak into the machine room 20, the cooling air generated by the cooling fan 36 can expel the leaked flammable refrigerant to the outside of the machine, preventing it from accumulating in the machine room 20. The amount of refrigerant sealed in the refrigerant circuit of the cooling device 30 varies depending on the cooling capacity of the cooling device 30, but the amount of flammable refrigerant sealed in is usually small, less than 150g, and the cooling air from the cooling fan 36 at a reduced rotation speed can sufficiently diffuse the flammable refrigerant. In this way, when the compressor 32 is stopped, rotating the cooling fan 36 at a lower speed than during cooling operation when the compressor 32 is running can reduce power consumption compared to continuously rotating the cooling fan 36 at a constant speed, while preventing the accumulation of flammable refrigerant in the machine room 20.

[0020] (Embodiment 2) Next, a cooling device according to Embodiment 2 will be described. The cooling device according to Embodiment 2 has basically the same configuration as the cooling device 30 of Embodiment 1, with only the rotation control of the cooling fan 36 being different.

[0021] As shown in Figure 4, the cooling device 30 according to Embodiment 2 is configured such that, when the compressor 32 is operating (when cooling operation is being performed), the control device 50 controls the cooling fan 36 to rotate at a first rotational speed, similar to Embodiment 1 described above. When the compressor 32 is stopped, the cooling fan 36 rotates at a second rotational speed lower than the first rotational speed, and the control device 50 is configured to control the cooling fan 36 to vary its rotational speed while the compressor 32 is stopped. By varying the rotational speed of the cooling fan 36 in this way, the state of airflow (wind flow) within the machine room 20 can be changed, making it possible to more effectively prevent the accumulation of flammable refrigerant within the machine room 20.

[0022] Specifically, in Embodiment 2, when the temperature detection means 44 detects a lower limit temperature (stopping the compressor 32), the rotation speed of the cooling fan 36 is switched from a first rotation speed to a lower second rotation speed. Furthermore, when a first switching time T1 has elapsed since the temperature detection means 44 detected the lower limit temperature, the control device 50 controls the cooling fan 36 to switch its rotation speed from the second rotation speed to a third rotation speed higher than the second rotation speed and rotate the cooling fan 36. Here, the third rotation speed may be any of the following, as long as it is higher than the second rotation speed: higher than the first rotation speed, the same as the first rotation speed, or lower than the first rotation speed. When the third rotational speed and the first rotational speed are set to the same rotational speed, speed control can be easily performed. When the third rotational speed is set to a rotational speed lower than the first rotational speed, there is an advantage in that power consumption when the compressor 32 is stopped can be suppressed while preventing the accumulation of flammable refrigerant in the machine room 20. Here, as shown in Figure 4, in this embodiment 2, the third rotational speed is set to be lower than the first rotational speed and higher than the second rotational speed, and the rotational speed of the cooling fan 36 is increased as the first switching time T1 elapses.

[0023] Furthermore, in the cooling device 30 of Embodiment 2, the control device 50 controls the cooling fan 36 so that when the second switching time T2 has elapsed since the cooling fan 36 was switched to the third rotational speed, the cooling fan 36 is switched back to the second rotational speed and rotated again. While the compressor 32 is stopped, the control device 50 controls the cooling fan 36 so that it repeats a cycle of varying the rotational speed between the second and third rotational speeds each time the first switching time T1 and the second switching time T2 have elapsed. In this way, by varying the rotational speed of the cooling fan 36 while the compressor 32 is stopped, the state of airflow in the machine room 20 is continuously changed, preventing the accumulation of flammable refrigerant in the machine room 20.

[0024] Here, it is preferable to set the first switching time T1 for switching the rotation speed of the cooling fan 36 from the second rotation speed to the third rotation speed to a time shorter than the minimum stop time of the compressor 32. By making the first switching time T1 shorter than the minimum stop time, it becomes possible to reliably vary the rotation speed of the cooling fan 36 while the compressor 32 is stopped, thereby effectively preventing the accumulation of flammable refrigerant in the machine room 20. Furthermore, it is preferable to set the sum of the first switching time T1 and the second switching time T2 (the time for one cycle from switching from the second rotation speed to the third rotation speed and then back to the second rotation speed) to a time shorter than the minimum stop time of the compressor 32. In this way, by making the cycle time for varying the rotation speed of the cooling fan 36 shorter than the minimum stop time, it becomes possible to effectively agitate the airflow in the machine room 20 while the compressor 32 is stopped, thereby more effectively preventing the accumulation of flammable refrigerant. In this embodiment 2, the compressor 32 is stopped with a minimum stop time of 5 minutes, a first switching time T1 of 2 minutes, and a second switching time T2 of 10 seconds. The cooling fan 36 is configured to repeatedly vary its rotation speed until the temperature detection means 44 detects the upper limit temperature. By switching the rotation speed of the cooling fan 36 multiple times during the minimum stop time, it is expected that the accumulation of flammable refrigerant in the machine room 20 can be prevented more effectively.

[0025] (Embodiment 3) Next, a cooling device according to Embodiment 3 will be described. The cooling device according to Embodiment 3 has basically the same configuration as the cooling device 30 of Embodiment 1, with only the rotation control of the cooling fan 36 being different.

[0026] As shown in Figure 5, the cooling device 30 according to Embodiment 3 is configured such that, when the compressor 32 is operating (when cooling operation is being performed), the control device 50 controls the cooling fan 36 to rotate at a first rotational speed, similar to Embodiment 1 described above. When the compressor 32 is stopped, the control device 50 is configured to control the cooling fan 36 to operate intermittently. In this way, by varying the rotational speed of the cooling fan 36 (varying between a rotating state and a stopped state) while the compressor 32 is operating, the state of airflow in the machine room 20 can be changed, making it possible to more effectively prevent the accumulation of flammable refrigerant in the machine room 20.

[0027] Specifically, in Embodiment 3, the cooling fan 36 is stopped when the temperature detection means 44 detects a lower limit temperature (stopping the compressor 32), and the control device 50 controls the cooling fan 36 to restart its operation and rotate it after a first switching time T1 has elapsed since the temperature detection means 44 detected the lower limit temperature. Here, the rotation speed of the cooling fan 36 when it restarts can be set to a rotation speed higher than the first rotation speed, the same as the first rotation speed, or lower than the first rotation speed. By setting the rotation speed of the cooling fan 36 when it restarts to the same as the first rotation speed, it becomes possible to vary the rotation speed of the cooling fan 36 while the compressor 32 is stopped simply by configuring the cooling fan 36 to be controlled on and off. Furthermore, if the rotation speed of the cooling fan 36 when it restarts is set to a rotation speed lower than the first rotation speed, there is an advantage in that power consumption while the compressor 32 is stopped can be suppressed while preventing the accumulation of flammable refrigerant in the machine room 20.

[0028] Furthermore, in the cooling device 30 of Embodiment 3, the control device 50 controls the cooling fan 36 so that it stops when a second switching time T2 has elapsed since the cooling fan 36 resumed operation. While the compressor 32 is stopped, the control device 50 controls the cooling fan 36 so that it repeats a cycle of operating and stopping the cooling fan 36 each time the first switching time T1 and the second switching time T2 have elapsed. In this way, while the compressor 32 is stopped, the cooling fan 36 is operated intermittently to vary its rotational speed, thereby continuously changing the state of airflow in the machine room 20 and preventing the accumulation of flammable refrigerant in the machine room 20.

[0029] (Example of change) The cooling device according to the present invention is not limited to those shown in the embodiments described above, and various modifications are possible. Furthermore, the configurations of each embodiment can be combined and applied as appropriate.

[0030] (1) While the compressor 32 is stopped, the cooling fan 36 is configured to operate at a constant speed (second rotational speed) or to vary its rotational speed as the switching time elapses. Alternatively, while the compressor 32 is stopped, the rotational speed of the cooling fan 36 may be continuously increased or decreased. (2) The cooling fan 36 is configured to alternately vary between a second rotational speed and a third rotational speed as time elapses while the compressor 32 is stopped (after the first switching time T1 and the second switching time T2 have elapsed). Alternatively, it may be configured to switch between operating at the second rotational speed and stopping operation as the first switching time T1 and the second switching time T2 have elapsed. (3) Although the explanation has been given using the case where the cooling device 30 is used in a refrigerator 10 as an example, it can also be applied to so-called storage facilities such as freezers, refrigerators and freezers, display cases and prefabricated storage rooms, and other air conditioning equipment. (4) The description has been given using a refrigerator 10 in which a machine room 20 is located on the lower side of a box body 12 with an insulated structure that defines a storage compartment 14 internally. However, the present invention can also be suitably applied to refrigerators of the type in which the machine room 20 is located on the upper side of the storage compartment (closed space) 14, or to horizontal refrigerators in which the machine room 20 is located on the side of the storage compartment (closed space) 14. [Explanation of Symbols]

[0031] 20 Machine room (open space), 32 Compressor, 34 Condenser, 36 Cooling fan, 38 Evaporator (cooler)

Claims

1. In a cooling system in which a compressor, a condenser, and a cooling fan for cooling the condenser are provided in an open space where air circulation is permitted, and a cooler is provided in a cooling space partitioned from the open space, and a flammable refrigerant is used as the refrigerant compressed by the compressor, When the compressor is operating, the cooling fan is operated at a first rotational speed, and when the compressor is stopped, the cooling fan is operated at a second rotational speed lower than the first rotational speed, The system is configured to variably control the cooling fan so that, after a first switching time has elapsed since the compressor stopped operating, the rotation speed of the cooling fan is switched from the second rotation speed to a third rotation speed that is higher than the second rotation speed and lower than the first rotation speed. A cooling device characterized by the following features.

2. The cooling device according to claim 1, characterized in that, with the operation of the compressor stopped, the cooling fan is configured to operate to return the rotation speed of the cooling fan from the third rotation speed back to the second rotation speed after a second switching time has elapsed since the cooling fan was switched from the second rotation speed.

3. When the compressor is stopped, it is configured to maintain the stopped state of the compressor for a minimum stop time. The cooling device according to claim 1 or 2, characterized in that the first switching time is set to a time shorter than the minimum stop time.

4. When the compressor is stopped, it is configured to maintain the stopped state of the compressor for a minimum stop time. The cooling device according to claim 2, characterized in that the sum of the first switching time and the second switching time is set to be shorter than the minimum stop time.

Images