Cooling device

Abstract

To provide a cooling device that can suppress the increase in power consumption. [Solution] In this cooling device 100, the control unit 6 is configured to perform a heater defrosting operation in which either the first defrosting heater 5a or the second defrosting heater 5b defrosts either the first evaporator 4a or the second evaporator 4b, and to control the maximum rotational speed of the common compressor 1 during the cooling defrosting operation in which the cooling operation is performed using the other of the first evaporator 4a or the second evaporator 4b that is not being defrosted, to be smaller than the maximum rotational speed of the common compressor 1 during the multiple cooling operation in which the cooling operation is performed using both the first evaporator 4a and the second evaporator 4b.

Description

Technical Field

[0001] The present invention relates to a cooling device, and particularly to a cooling device including a compressor and an evaporator.

Background Art

[0002] Conventionally, a cooling device including a compressor and an evaporator has been known (for example, see Patent Document 1).

[0003] In Patent Document 1, a cooling device is disclosed which includes a first showcase, a second showcase, a first evaporator disposed in the first showcase, a second evaporator disposed in the second showcase, and a compressor. In Patent Document 1, one compressor is provided for the first evaporator and the second evaporator. Further, in Patent Document 1, refrigerant is supplied from the compressor to each of the first evaporator and the second evaporator to cool the inside of the showcase.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although not disclosed in Patent Document 1 mentioned above, frost forms on the evaporator when a cooling operation is performed to cool a showcase, so a defrosting operation is performed by heating the evaporator with a heater. In a cooling system with one evaporator, the compressor is stopped and the defrosting heater is driven, whereas in a cooling system with multiple evaporators, the compressor (common compressor) may be driven to cool one of the multiple evaporators while the defrosting heater is driven to defrost the other. In this case, the power consumption of a cooling system with multiple evaporators may increase compared to a cooling system with one evaporator. Therefore, there is a need for a cooling system that can suppress the increase in power consumption even when multiple evaporators are provided.

[0006] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a cooling device that can suppress an increase in power consumption even when equipped with multiple evaporators. [Means for solving the problem]

[0007] To achieve the above objective, the cooling device according to the first aspect of this invention comprises a first evaporator that evaporates a refrigerant to cool a first cooling chamber, a second evaporator arranged in parallel with the first evaporator and evaporates a refrigerant to cool a second cooling chamber, a common compressor that supplies refrigerant to the first and second evaporators, a first defrost heater for defrosting the first evaporator, a second defrost heater for defrosting the second evaporator, and a control unit that controls the common compressor. The control unit is configured to perform a heater defrosting operation in which either the first or second evaporator is defrosted using either the first or second defrost heater, and to control the maximum rotational speed of the common compressor during a cooling defrosting operation in which the cooling operation is performed using the other of the first or second evaporator that is not being defrosted, so that it is less than the maximum rotational speed of the common compressor during a multiple cooling operation in which the first and second evaporators are used for cooling.

[0008] In the cooling device according to the first aspect of this invention, as described above, the control unit is configured to perform a heater defrosting operation in which either the first defrosting heater or the second defrosting heater is used to defrost either the first or second evaporator, and to control the maximum rotational speed of the common compressor during the cooling defrosting operation, in which the cooling operation is performed using the other of the first or second evaporator that is not being defrosted, to be smaller than the maximum rotational speed of the common compressor during the multiple cooling operation, in which the cooling operation is performed using the first and second evaporators. As a result, during the cooling defrosting operation, the maximum rotational speed of the common compressor is smaller than the maximum rotational speed of the common compressor during the multiple cooling operation, so that power is consumed by operating the defrosting heater, while the power consumption of the common compressor can be reduced. As a result, even when there are multiple evaporators, the increase in power consumption can be suppressed.

[0009] In the cooling system according to the first aspect described above, preferably, the control unit is configured to control the maximum rotational speed of the common compressor when performing cooling and defrosting operations to be half or less of the maximum rotational speed of the common compressor when performing multiple cooling operations. With this configuration, when performing cooling and defrosting operations, the maximum rotational speed of the common compressor can be reduced to half or less of that during multiple cooling operations, thereby effectively suppressing an increase in power consumption.

[0010] In the cooling device according to the first aspect described above, preferably, the first cooling chamber and the second cooling chamber include a door and a condensation-preventing heater to suppress condensation on the door, and the control unit is configured to perform an overheating operation for a predetermined time before starting the defrosting operation, by supplying more power to the condensation-preventing heater of the cooling chamber where the evaporator performing the defrosting operation is located than during cooling. With this configuration, by overheating the door, the difference between the outside temperature and the temperature of the door can be reduced, thereby suppressing the occurrence of condensation on the door. As a result, the condensation-preventing heater can be stopped during the defrosting operation, so the increase in power consumption during defrosting can be suppressed compared to the case where the first or second defrosting heater and the condensation-preventing heater are driven simultaneously.

[0011] In this case, preferably, the control unit is configured to perform overheating operation based on at least one of the outside air temperature and humidity. With this configuration, condensation is more likely to occur when there is a large difference between the outside air temperature and the temperature inside the cooling chamber. Therefore, by changing the overheating temperature based on the outside air temperature, it is possible to effectively suppress the occurrence of condensation while stopping the anti-condensation heater and suppressing an increase in power consumption. Also, since condensation is more likely to occur when the humidity is high, by changing the overheating temperature based on the humidity, it is possible to effectively suppress the occurrence of condensation while stopping the anti-condensation heater and suppressing an increase in power consumption.

[0012] In the cooling device according to the first aspect described above, preferably, the first cooling chamber and the second cooling chamber include a door and a condensation-preventing heater to suppress condensation on the door, and the condensation-preventing heater is configured to switch to the off state based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the on state. With this configuration, the condensation-preventing heater can be turned off during defrosting when at least one of the first defrost heater and the second defrost heater is in the on state, thereby reliably preventing the condensation-preventing heater and the first and second defrost heaters from operating together.

[0013] In this case, preferably, the system further includes a switch unit for the first defrost heater that switches the first defrost heater between an ON state and an OFF state, a switch unit for the second defrost heater that switches the second defrost heater between an ON state and an OFF state, and a switch unit for the anti-condensation heater that switches the anti-condensation heater between an ON state and an OFF state. The system is configured such that, based on the fact that at least one of the first defrost heater and the second defrost heater has been switched to the ON state by at least one of the first defrost heater and the second defrost heater, the anti-condensation heater switch unit switches the anti-condensation heater to the OFF state. With this configuration, the ON state of the first defrost heater and the second defrost heater and the ON state of the anti-condensation heater can be easily switched by switching the switches.

[0014] In the configuration that includes the above-described switch unit for the anti-condensation heater, preferably, the anti-condensation heater switch unit includes an interlocking switch unit that switches the anti-condensation heater between the ON and OFF states in conjunction with the first defrost heater switch unit and the second defrost heater switch unit, and an optional switch unit that can switch the anti-condensation heater between the ON and OFF states independently of the first defrost heater switch unit and the second defrost heater switch unit. With this configuration, by including the interlocking switch unit, the anti-condensation heater can be turned OFF during defrosting when the first defrost heater or the second defrost heater is ON, thus reducing power consumption, unlike when the first defrost heater, the second defrost heater, and the anti-condensation heater are all driven. Furthermore, since the anti-condensation heater can be turned OFF by the optional switch, the increase in power consumption can be more effectively suppressed by turning OFF all of the first defrost heater, the second defrost heater, and the anti-condensation heater.

[0015] A cooling device according to the second aspect of this invention preferably comprises: a first evaporator that evaporates a refrigerant to cool a first cooling chamber; a second evaporator arranged in parallel with the first evaporator and evaporates a refrigerant to cool a second cooling chamber; a common compressor that supplies refrigerant to the first and second evaporators; a first defrost heater for defrosting the first evaporator; a second defrost heater for defrosting the second evaporator; a control unit that controls the common compressor; doors provided in the first and second cooling chambers; and a condensation prevention heater that suppresses condensation on the doors, wherein the condensation prevention heater is switched off based on the fact that at least one of the first defrost heater and the second defrost heater is switched on.

[0016] In the cooling device according to the second aspect of this invention, as described above, the condensation prevention heater is configured to switch to the off state based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the on state. With this configuration, the condensation prevention heater can be turned off during defrosting when at least one of the first defrost heater and the second defrost heater is on, thus reducing power consumption, unlike when both the condensation prevention heater and the defrost heater are driven. As a result, even when multiple evaporators are provided, the increase in power consumption can be suppressed.

[0017] In a cooling device according to the second aspect of this invention, preferably, the device further includes a switch unit for a first defrost heater that switches the first defrost heater between an ON state and an OFF state, a switch unit for a second defrost heater that switches the second defrost heater between an ON state and an OFF state, and a switch unit for a condensation heater that switches the condensation heater between an ON state and an OFF state, wherein at least one of the first defrost heater switch unit and the second defrost heater switch unit switches at least one of the first defrost heater and the second defrost heater to the ON state, and the condensation heater switch unit switches the condensation heater to the OFF state. With this configuration, the ON state of the first defrost heater and the second defrost heater and the ON state of the condensation heater can be easily switched by switching the switches. [Effects of the Invention]

[0018] According to the present invention, as described above, it is possible to provide a cooling device that can suppress an increase in power consumption even when equipped with multiple evaporators. [Brief explanation of the drawing]

[0019] [Figure 1] This figure shows an example of the cooling device according to this embodiment. [Figure 2] This is a diagram showing the configuration of the cooling system. [Figure 3]It is a diagram showing the relationship between the operation modes of the first cooling chamber and the second cooling chamber and the rotational speed of the compressor. [Figure 4] It is a diagram showing the relationship between the outside air temperature, humidity, and overheating operation. [Figure 5] It is a diagram showing a circuit to which a switch section for the first defrost heater, a switch section for the second defrost heater, and a switch section for the anti-condensation heater are connected. [Figure 6] It is a diagram showing the relationship between the on and off states of the switch section for the first defrost heater and the switch section for the second defrost heater and the on and off states of the switch section for the anti-condensation heater.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments embodying the present invention will be described based on the drawings.

[0021] Referring to FIGS. 1 to 6, the configuration of the cooling device 100 according to the present embodiment will be described. In the present embodiment, one direction in the horizontal plane is defined as the X direction. Also, the vertical direction (the vertical direction) of the cooling device 100 is defined as the Z direction. Further, the direction orthogonal to the X direction and the Z direction of the cooling device 100 (the other direction in the horizontal plane) is defined as the Y direction.

[0022] As shown in FIGS. 1 and 2, the cooling device 100 is, for example, a showcase installed in a supermarket and a convenience store, etc., for cooling (freezing) products. The cooling device 100 is a single showcase including two adjacent cooling chambers, a first cooling chamber 101 and a second cooling chamber 102. The cooling device 100 is a reach-in type showcase for refrigeration or freezing. Also, the showcase is arranged at a position away from the wall of the store, for example, near the center of the store.

[0023] The first cooling chamber 101 has a first door 101a attached to the X1 side. The second cooling chamber 102 has a second door 102a attached to the X2 side. One side in the X direction is referred to as the X1 side, and the other side in the X direction is referred to as the X2 side. In the cooling device 100, by opening the first door 101a, products can be replenished and removed from the X1 side to the first cooling chamber 101. Similarly, by opening the second door 102a, products can be replenished and removed from the X1 side and the X2 side to the second cooling chamber 102. Both the first cooling chamber 101 and the second cooling chamber 102 are equipped with multiple shelves 104, and are configured to cool (freeze) articles (products) placed on the shelves 104. The first door 101a and the second door 102a are examples of the "doors" described in the claims. The cooling device 100 is connected to the commercial power supply.

[0024] The first door section 101a and the second door section 102a each include a rectangular glass door and a metal frame surrounding the glass door. Four of the first door section 101a and four of the second door section 102a are installed for the first cooling chamber 101 and the second cooling chamber 102, respectively.

[0025] The cooling device 100 comprises a refrigeration cycle 103, a control unit 6, and a condensation prevention heater 7.

[0026] The refrigeration cycle is located below the showcase and is used to cool or freeze the first cooling chamber 101 and the second cooling chamber 102. The refrigeration cycle 103 includes a common compressor 1, a condenser 2, a first expansion section 3a, a second expansion section 3b, a first evaporator 4a, a second evaporator 4b, a first defrost heater 5a, and a second defrost heater 5b. The power consumption of the refrigeration cycle 103 increases as the rotational speed of the common compressor 1 increases.

[0027] The common compressor 1 is configured to supply refrigerant to the first evaporator 4a and the second evaporator 4b. The common compressor 1 is configured to compress the refrigerant and change it to a high pressure. Specifically, the refrigerant compressed by the common compressor 1 is supplied to the condenser 2, then passes through the first expansion section 3a and the second expansion section 3b, and is supplied to the first evaporator 4a and the second evaporator 4b. The common compressor 1 is configured to be powered by commercial power.

[0028] The condenser 2 is configured to cool and liquefy the refrigerant compressed in the common compressor 1. The refrigerant condensed by the condenser 2 is supplied to the first expansion section 3a and the second expansion section 3b. One condenser 2 is provided for each of the first evaporator 4a and the second evaporator 4b.

[0029] The first expansion section 3a is located in the first cooling chamber 101 and is configured to supply refrigerant to the first evaporator 4a. The second expansion section 3b is located in the second cooling chamber 102 and is configured to supply refrigerant to the second evaporator 4b. The first expansion section 3a and the second expansion section 3b each expand the refrigerant supplied from the condenser 2, converting it into a low-pressure, low-temperature refrigerant. The first expansion section 3a and the second expansion section 3b are arranged in parallel, and the refrigerant is distributed and supplied from the condenser 2 to them.

[0030] The first evaporator 4a is configured to cool the first cooling chamber 101. The second evaporator 4b is arranged in parallel with the first evaporator 4a and is configured to cool the second cooling chamber 102. The first evaporator 4a performs heat exchange between the refrigerant supplied from the first expansion section 3a and the object to be cooled, cooling the object by evaporation of the refrigerant. The second evaporator 4b performs heat exchange between the refrigerant supplied from the second expansion section 3b and the object to be cooled, cooling the object by evaporation of the refrigerant (changing from liquid phase to gas phase or gas-liquid two-phase). The object to be cooled is, for example, an article arranged in the first cooling chamber 101 and the second cooling chamber 102, and the object to be cooled is cooled via the air cooled by the first evaporator 4a and the second evaporator 4b. The refrigerants evaporated in the first evaporator 4a and the second evaporator 4b are combined and supplied to the common compressor 1.

[0031] The first defrost heater 5a defrosts the first evaporator 4a by heating it. The second defrost heater 5b is configured to defrost the second evaporator 4b by heating it. The first defrost heater 5a is located near the first evaporator 4a. The second defrost heater 5b is located near the second evaporator 4b. The first defrost heater 5a and the second defrost heater 5b are located independently in the first cooling chamber 101 and the second cooling chamber 102, respectively. The defrosting operation of the first evaporator 4a by the first defrost heater 5a and the defrosting operation of the second evaporator 4b by the second defrost heater 5b start at the same time, but end at different times. The first defrost heater 5a and the second defrost heater 5b are powered by the commercial power supply, and are configured so that the heating temperature increases as the amount of power supplied increases.

[0032] The control unit 6 includes a processing unit such as a CPU (Central Processing Unit) and memory such as RAM. The control unit 6 is configured to control the common compressor 1 to cool the first cooling chamber 101 and the second cooling chamber 102. The control unit 6 is also configured to control the first defrost heater 5a and the second defrost heater 5b to defrost the first evaporator 4a and the second evaporator 4b. The control unit 6 is also configured to control the anti-condensation heater 7 to prevent condensation on the first door section 101a and the second door section 102a. Multiple control units (two or more) may be provided to control the first evaporator 4a and the second evaporator 4b respectively, or one unit may be provided to control the first evaporator 4a and the second evaporator 4b together.

[0033] The anti-condensation heater 7 includes an anti-condensation heater 7a for the glass door and an anti-condensation heater 7b for the frame. The anti-condensation heater 7a for the glass door is configured to heat the glass door. The anti-condensation heater 7b for the frame is configured to heat the metal frame. By heating the glass door and the frame with the anti-condensation heater 7a and the anti-condensation heater 7b for the frame, the anti-condensation heater 7 suppresses condensation on the first door section 101a and the second door section 102a. Hereinafter, "anti-condensation heater 7" refers to both the anti-condensation heater 7a for the glass door and the anti-condensation heater 7b for the frame. The anti-condensation heater 7 is powered by a commercial power source, and is configured so that the heating temperature increases as the amount of power supplied increases.

[0034] (Control during cooling operation) The control unit 6 is configured to perform a cooling operation to cool the first cooling chamber 101 and the second cooling chamber 102 by controlling the rotational speed of the common compressor 1. Specifically, it is configured to increase or decrease the rotational speed of the common compressor 1 so that the first cooling chamber 101 and the second cooling chamber 102 reach set temperatures, based on the superheating degree of the first evaporator 4a and the second evaporator 4b. The superheating degree is calculated from the inlet temperature and outlet temperature of the first evaporator 4a and the second evaporator 4b, respectively.

[0035] (Defrost control) The control unit 6 is configured to start the defrosting operation of the first evaporator 4a and the defrosting operation of the second evaporator 4b simultaneously. The control unit 6 has, for example, a pre-stored start time for the defrosting operation, and is configured to start the defrosting operation when the start time arrives. The control unit 6 also obtains whether or not to terminate the defrosting operation of the first evaporator 4a based on the superheating level of the first evaporator 4a. The control unit 6 also obtains whether or not to terminate the defrosting operation of the second evaporator 4b based on the superheating level of the second evaporator 4b. When the defrosting operation of the first evaporator 4a and the defrosting operation of the second evaporator 4b are started simultaneously, the control unit 6 is configured to control the rotation speed of the common compressor 1 to zero (stop it).

[0036] The control unit 6 is configured to perform a heater defrosting operation in which either the first defrosting heater 5a or the second defrosting heater 5b defrosts either the first evaporator 4a or the second evaporator 4b, and to control the maximum rotational speed of the common compressor 1 during a cooling defrosting operation in which the other of the first evaporator 4a or the second evaporator 4b that is not being defrosted is cooled, to be less than the maximum rotational speed of the common compressor 1 during a multiple cooling operation in which both the first evaporator 4a and the second evaporator 4b are cooled. For example, in a cooling defrosting operation in which the defrosting operation of the first evaporator 4a has finished but the defrosting operation of the second evaporator 4b continues, the control unit 6 is configured to reduce the rotational speed of the common compressor 1.

[0037] As shown in Figure 3, in this embodiment, the control unit 6 is configured to control the maximum rotational speed of the common compressor 1 during cooling and defrosting operation to be less than or equal to half of the maximum rotational speed of the common compressor 1 during multiple cooling operations. For example, the control unit 6 is configured to set the maximum rotational speed of the common compressor 1 to 60Hz during multiple cooling operations, and to control the common compressor 1 to operate normally so as not to exceed the maximum rotational speed during multiple cooling operations. On the other hand, the control unit 6 is configured to set the maximum rotational speed of the common compressor 1 to 30Hz during cooling and defrosting operations, and to control the common compressor 1 to operate at a low speed so as not to exceed the maximum rotational speed. Conventionally, the maximum rotational speed of the common compressor 1 was the same during multiple cooling operations and cooling and defrosting operations, resulting in the highest power consumption during cooling and defrosting operations. In contrast, in this embodiment, by reducing the maximum rotational speed of the common compressor 1 during cooling and defrosting operations compared to the maximum rotational speed of the common compressor 1 during multiple cooling operations, the cooling process is performed more gradually than in the conventional method, while suppressing an increase in power consumption. Furthermore, the maximum rotational speed of the common compressor 1 during cooling and defrosting operation is set to ensure sufficient cooling (to adequately cool the items to be cooled).

[0038] (Overheating operation) The control unit 6 is configured to perform an overheating operation for a predetermined time on the condensation prevention heater 7 in the cooling chamber where the evaporator for defrosting is installed, before starting the defrosting operation. Overheating operation is an operation that preheats the door by increasing the amount of power supplied to the condensation prevention heater 7 in the cooling chamber where the evaporator for defrosting is installed, compared to the amount supplied during cooling. The control unit 6 is configured to perform the overheating operation based on at least one of the outside air temperature and humidity. The control unit 6 is configured to increase the amount of power supplied to the condensation prevention heater 7 as at least one of the humidity or temperature increases.

[0039] As shown in Figure 4, the control unit 6 has a table set up for overheating operation based on the outside temperature and humidity. The outside temperature and humidity are obtained from a thermometer and hygrometer placed in the showcase. For example, if the outside temperature is below 25°C and the humidity is below 50%, the difference between the outside temperature and the temperature inside the cooled showcase is small, and condensation is unlikely due to the low humidity, so the overheating operation is set to be off. If the outside temperature is 25°C or higher and the humidity is below 50%, the difference between the outside temperature and the temperature inside the cooled showcase becomes large, so the overheating operation is set to be performed for 10 minutes. If the outside temperature is below 25°C and the humidity is 50% or higher, the humidity is high and condensation is likely, so the overheating operation is set to be performed for 15 minutes. If the outside temperature is 25°C or higher and the humidity is 50% or higher, the difference between the outside temperature and the temperature inside the cooled showcase becomes large and condensation is likely, so the overheating operation is set to be performed for 20 minutes. After performing the overheating operation, the control unit 6 starts the defrosting operation and stops the anti-condensation heater 7.

[0040] Conventionally, the anti-condensation heater 7 was driven (powered) independently of the control of the defrost heater, so the timing of driving (powering) the defrost heater and the anti-condensation heater sometimes overlapped. Also, the anti-condensation heater 7 was operated with a constant amount of power regardless of whether the evaporator was in defrosting or cooling operation, or powered based on a table in which the power supply rate was set based on temperature and humidity. As a result, the anti-condensation heater 7 was driven during defrosting operation, causing the peak power consumption to be the highest. On the other hand, in this embodiment, since power to the anti-condensation heater 7 can be stopped when the defrosting operation of the first defrost heater 5a and the second defrost heater 5b is started after overheating operation, the increase in power consumption can be suppressed by stopping the driving of the anti-condensation heater 7a for the glass door and the anti-condensation heater 7b for the frame.

[0041] As shown in Figure 5, the cooling device 100 includes a switch unit 8a for the first defrost heater, a switch unit 8b for the second defrost heater, and a switch unit 9 for the anti-condensation heater. The anti-condensation heater 7 is configured to switch to the off state based on the fact that at least one of the first defrost heater 5a and the second defrost heater 5b is switched to the ON state.

[0042] The switch unit 8a for the first defrost heater is configured to switch the first defrost heater 5a between an on state and an off state. The switch unit 8b for the second defrost heater is configured to switch the second defrost heater 5b between an on state and an off state. More specifically, the switch unit 8a for the first defrost heater is configured to switch the circuit of the first defrost heater 5a between a connected state and an unconnected state. The switch unit 8b for the second defrost heater is configured to switch the circuit of the second defrost heater 5b between a connected state and an unconnected state.

[0043] The condensation heater switch unit 9 is configured to switch the condensation heater 7 between an on state and an off state. The condensation heater switch unit 9 is configured to switch the condensation heater 7 circuit between a connected state and an unconnected state. Specifically, the condensation heater switch unit 9 includes an interlocking switch unit 9a that switches the condensation heater 7 between an on state and an off state in conjunction with the first defrost heater switch unit 8a and the second defrost heater switch unit 8b, and an optional switch unit 9b that can switch the condensation heater 7 between an on state and an off state independently of the first defrost heater switch unit 8a and the second defrost heater switch unit 8b. The optional switch unit 9b is, for example, an SSR (solid state relay).

[0044] In this embodiment, the switch section 8a for the first defrost heater and the switch section 8b for the second defrost heater are A contacts of the relay circuit for driving the first defrost heater 5a and the second defrost heater 5b, and the interlocking switch section 9a of the switch section 9 for the anti-condensation heater is a B contact of the relay circuit for driving the first defrost heater 5a and the second defrost heater 5b. The anti-condensation heater 7 is positioned near the B contact of the relay circuit for driving the first defrost heater 5a and the second defrost heater 5b. The control unit 6 is configured to turn on either the switch section 8a for the first defrost heater or the switch section 8b for the second defrost heater when defrosting starts, and to turn off either the switch section 8a for the first defrost heater or the switch section 8b for the second defrost heater when defrosting operation ends.

[0045] The interlocking switch section 9a includes a first interlocking switch section 91a and a second interlocking switch section 92a. The switch section 8a for the first defrost heater and the first interlocking switch section 91a are configured to switch in conjunction with each other. In Figure 5, the interlocking is indicated by a dashed line. The circuit of the first defrost heater 5a is connected by the switch section 8a for the first defrost heater, turning the first defrost heater 5a ON. Conversely, the circuit of the anti-condensation heater 7 is disconnected by the first interlocking switch section 91a, turning the anti-condensation heater 7 OFF. The switch section 8b for the second defrost heater and the second interlocking switch section 92a are also configured to switch in conjunction with each other. When the second defrost heater 5b is turned ON by the switch section 8b for the second defrost heater, the anti-condensation heater 7 is turned OFF by the second interlocking switch section 92a. The first interlocking switch unit 91a and the second interlocking switch unit 92a are connected in series, and if at least one of them is disconnected, electricity is not supplied to the condensation-preventing heater 7, and it does not operate.

[0046] The optional switch unit 9b includes a first optional switch unit 91b and a second optional switch unit 92b. The first optional switch unit 91b is positioned corresponding to the glass door condensation heater 7a. The second optional switch unit 92b is positioned corresponding to the frame condensation heater 7b. The first optional switch unit 91b can switch the glass door condensation heater 7a between the ON and OFF states. The second optional switch unit 92b can also switch the frame condensation heater 7b between the ON and OFF states. The optional switch unit 9b is used to switch the glass door condensation heater 7a and the frame condensation heater 7b to the OFF state when the first interlocking switch unit 91a and the second interlocking switch unit 92a are connected. This allows the first defrost heater 5a, the second defrost heater 5b, and the condensation heater 7 to be stopped. The optional switch unit 9b can be switched.

[0047] Conventionally, the anti-condensation heater 7 was driven independently of the defrost heater control, and the anti-condensation heater 7a for the glass door and the anti-condensation heater 7b for the frame were controlled independently of each other. As a result, the timing of driving (energizing) the defrost heater and the anti-condensation heater overlapped, increasing power consumption and causing the peak power consumption to reach its maximum. On the other hand, in this embodiment, when the defrosting operation of the first defrost heater 5a and the second defrost heater 5b is started, the power supply to the anti-condensation heater 7 is stopped, thereby stopping the driving of the anti-condensation heater 7a for the glass door and the anti-condensation heater 7b for the frame, and thus the increase in power consumption can be suppressed. Furthermore, in this embodiment, the switch that was conventionally provided for controlling the defrost heater is used as the interlocking switch section 9a of the anti-condensation heater switch section 9, and no parts are added from the conventional configuration. Furthermore, by including an optional switch section 9b, even if a problem such as welding occurs in either the interlocking switch section 9a or the optional switch section 9b, the timing for driving the defrost heater 4 and the timing for driving the anti-condensation heater 7 by the switch that is not experiencing the problem are ensured not to overlap.

[0048] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0049] In this embodiment, as described above, the control unit 6 is configured to perform a heater defrosting operation in which either the first defrosting heater 5a or the second defrosting heater 5b defrosts either the first evaporator 4a or the second evaporator 4b, and to control the maximum rotational speed of the common compressor 1 during a cooling defrosting operation in which the other of the first evaporator 4a or the second evaporator 4b that is not being defrosted is cooled, to be smaller than the maximum rotational speed of the common compressor 1 during a multiple cooling operation in which the first evaporator 4a and the second evaporator 4b are cooled. As a result, during the cooling defrosting operation, the maximum rotational speed of the common compressor 1 is smaller than the maximum rotational speed of the common compressor 1 during a multiple cooling operation, so that power is consumed by operating the defrosting heater 4, while the power consumption of the common compressor 1 is reduced. As a result, even when multiple evaporators are provided, the increase in power consumption can be suppressed.

[0050] Furthermore, in this embodiment, as described above, the control unit 6 is configured to control the maximum rotational speed of the common compressor 1 when performing cooling and defrosting operations to be half or less of the maximum rotational speed of the common compressor 1 when performing multiple cooling operations. As a result, when performing cooling and defrosting operations, the maximum rotational speed of the common compressor 1 can be reduced to half or less of that during multiple cooling operations, thereby effectively suppressing an increase in power consumption.

[0051] Furthermore, in this embodiment, as described above, the first cooling chamber 101 and the second cooling chamber 102 include a first door section 101a (second door section 102a) and a condensation prevention heater 7 that suppresses condensation on the first door section 101a. The control unit 6 is configured to perform an overheating operation for a predetermined time before starting the defrosting operation, by supplying more power to the condensation prevention heater 7 of the cooling chamber where the evaporator performing the defrosting operation is located than during cooling. By overheating the first door section 101a, the difference between the external temperature and the temperature of the first door section 101a can be reduced, thereby suppressing the occurrence of condensation on the first door section 101a. As a result, the condensation prevention heater 7 can be stopped during the defrosting operation, thus suppressing the increase in power consumption during defrosting compared to the case where the first defrosting heater 5a or the second defrosting heater 5b and the condensation prevention heater 7 are driven simultaneously.

[0052] Furthermore, in this embodiment, as described above, the control unit 6 is configured to perform overheating operation based on at least one of the outside air temperature and humidity. As a result, since condensation is more likely to occur when there is a large difference between the outside air temperature and the temperature inside the cooling chamber, by changing the overheating temperature based on the outside air temperature, it is possible to effectively suppress the occurrence of condensation while suppressing an increase in power consumption. Also, since condensation is more likely to occur when the humidity is high, by changing the overheating temperature based on the humidity, it is possible to effectively suppress the occurrence of condensation while suppressing an increase in power consumption.

[0053] Furthermore, in this embodiment, as described above, the first cooling chamber 101 and the second cooling chamber 102 include a first door portion 101a (second door portion 102a) and a condensation prevention heater 7 that suppresses condensation on the first door portion 101a. The condensation prevention heater 7 is configured to switch to the off state based on the fact that at least one of the first defrost heater 5a and the second defrost heater 5b is switched to the on state. As a result, the condensation prevention heater 7 can be turned off during defrosting when at least one of the first defrost heater 5a and the second defrost heater 5b is in the on state, thereby reliably preventing the condensation prevention heater 7 from being driven simultaneously with the first defrost heater 5a and the second defrost heater 5b.

[0054] Furthermore, in this embodiment, as described above, the system further includes a first defrost heater switch unit 8a for switching the first defrost heater 5a between an ON state and an OFF state, a second defrost heater switch unit 8b for switching the second defrost heater 5b between an ON state and an OFF state, and a condensation heater switch unit 9 for switching the condensation heater 7 between an ON state and an OFF state. The system is configured such that, based on the fact that at least one of the first defrost heater 5a and the second defrost heater 5b is switched to the ON state by at least one of the first defrost heater switch unit 8a and the second defrost heater switch unit 8b, the condensation heater switch unit 9 switches the condensation heater 7 to the OFF state. As a result, the ON state of the first defrost heater 5a and the second defrost heater 5b and the ON state of the condensation heater 7 can be easily switched by switching the switches.

[0055] Furthermore, in the first embodiment, as described above, the switch unit 9 for the anti-condensation heater includes an interlocking switch unit 9a that switches the anti-condensation heater 7 between the ON state and the OFF state in conjunction with the switch unit 8a for the first defrost heater and the switch unit 8b for the second defrost heater, and an optional switch unit 9b that can switch the anti-condensation heater 7 between the ON state and the OFF state independently of the switch unit 8a for the first defrost heater and the switch unit 8b for the second defrost heater. As a result, by providing the interlocking switch unit 9a, the anti-condensation heater 7 can be turned OFF during defrosting when the first defrost heater 5a or the second defrost heater 5b is ON. Therefore, unlike when the first defrost heater 5a, the second defrost heater 5b, and the anti-condensation heater 7 are all driven, power consumption can be reduced. Furthermore, since the dew-preventing heater 7 can be turned off by the optional switch unit 9b, the first defrost heater 5a, the second defrost heater 5b, and the dew-preventing heater 7 can all be turned off, thereby more effectively suppressing the increase in power consumption.

[0056] [Differentiation] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and further includes all modifications (exceptions) within the meaning and scope equivalent to the claims.

[0057] For example, in the above embodiment, the cooling device was shown to include two evaporators, a first evaporator and a second evaporator, but the present invention is not limited thereto. The present invention may include three or more evaporators.

[0058] Furthermore, while the above embodiment shows an example in which the maximum rotational speed of the common compressor during cooling and defrosting operation is controlled to be half of the maximum rotational speed of the common compressor during multiple cooling operations, the present invention is not limited to this. In the present invention, it is sufficient that the maximum rotational speed of the common compressor during cooling and defrosting operation is smaller than the maximum rotational speed of the common compressor during multiple cooling operations. For example, the maximum rotational speed of the common compressor during cooling and defrosting operation may be set to one-quarter of the maximum rotational speed of the common compressor during multiple cooling operations.

[0059] Furthermore, in the above embodiment, an example was shown in which the control unit is configured to perform both control to reduce the maximum rotational speed of the common compressor during cooling and defrosting operation and to perform overheating operation, but the present invention is not limited to this. In the present invention, the control unit does not have to perform overheating operation. In this case, the cooling device may or may not have a configuration in which, based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the ON state by at least one of the first defrost heater and the second defrost heater, the condensation heater switch unit switches the condensation heater to the OFF state.

[0060] Furthermore, although the above embodiment shows an example in which the switch section for the condensation-preventing heater includes an interlocking switch section and an arbitrary switch section, the present invention is not limited thereto. In the present invention, the switch section for the condensation-preventing heater may include either an interlocking switch section or an arbitrary switch section.

[0061] Furthermore, in the present invention, in a cooling device configured such that at least one of the first defrost heater and the second defrost heater is switched ON by at least one of the first defrost heater and the second defrost heater switch unit, the dew prevention heater switch unit switches the dew prevention heater to the OFF state, the control unit may be configured not to perform control to reduce the maximum rotational speed of the common compressor during cooling defrost operation or the maximum rotational speed of the common compressor during multiple cooling operations. In this case, the control unit may or may not perform overheating operation.

[0062] Furthermore, in the above embodiment, an example was shown in which the condensation heater switch unit switches the condensation heater to the off state based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the ON state by at least one of the first defrost heater and the second defrost heater switch unit, but the present invention is not limited to this. In the present invention, the control unit may be configured to switch at least one of the first defrost heater and the second defrost heater to the ON state and the condensation heater switch unit switches the condensation heater to the off state without providing the first defrost heater switch unit, the second defrost heater switch unit and the condensation heater switch unit.

[0063] Furthermore, although the above embodiment shows an example in which the control unit performs overheating operation based on both temperature and humidity, the present invention is not limited to this. In the present invention, the control unit may be configured to perform overheating operation based on either temperature or humidity.

[0064] Furthermore, although the above embodiment shows an example in which the control unit performs overheating operation based on both temperature and humidity, the present invention is not limited thereto. In the present invention, the control unit may be configured to learn past data related to defrosting operation and set the time for performing overheating operation and the amount of power to be supplied.

[0065] Furthermore, although this embodiment shows an example in which the control unit is configured to perform overheating operation based on temperature and humidity, the present invention is not limited thereto. In the present invention, the control unit may be configured to suppress an increase in power consumption by adjusting the amount of power supplied to the defrosting heater during defrosting operation and cooling operation based on temperature and humidity.

[0066] Furthermore, although this embodiment shows a showcase as the cooling device, the present invention is not limited to this. In the present invention, the cooling device may be an air conditioner or a vending machine. In this case, the cooling device may be configured to control the maximum rotational speed of the common compressor during cooling and defrosting operation to be less than the maximum rotational speed of the common compressor during multiple cooling operations in which cooling is performed by the first evaporator and the second evaporator, without providing a condensation prevention heater. [Explanation of symbols]

[0067] 1. Common Compressor 4a First evaporator 4b Second evaporator 5a First defrost heater 5b Second defrost heater 6 Control Unit 7. Anti-condensation heater 8a Switch section for the first defrost heater 8b Switch section for the second defrost heater 9. Switch section for condensation-preventing heater 9a Interlocking switch section 9b Optional switch section 100 Cooling device 101 1st cooling room 101a First door section (door section) 102 Second cooling room 102a Second door section (door section)

Claims

1. A first evaporator that cools the first cooling chamber by evaporating the refrigerant, A second evaporator is arranged in parallel with the first evaporator and evaporates the refrigerant to cool the second cooling chamber, A common compressor that supplies refrigerant to the first evaporator and the second evaporator, A first defrost heater for defrosting the first evaporator, A second defrost heater for defrosting the second evaporator, The system comprises a control unit for controlling the aforementioned common compressor, The control unit is configured to perform a heater defrosting operation in which either the first defrosting heater or the second defrosting heater defrosts either the first evaporator or the second evaporator, and to control the common compressor's maximum rotational speed during a cooling defrosting operation in which the other of the first or second evaporators that is not being defrosted is cooled to be less than the common compressor's maximum rotational speed during a multiple cooling operation in which the first and second evaporators are cooled.

2. The cooling device according to claim 1, wherein the control unit is configured to control the maximum rotational speed of the common compressor when performing the cooling and defrosting operation to be half or less of the maximum rotational speed of the common compressor when performing the multiple cooling operations.

3. The first cooling chamber and the second cooling chamber each include a door and a condensation-preventing heater that suppresses condensation on the door. The cooling apparatus according to claim 1, wherein the control unit is configured to perform an overheating operation for a predetermined time, before starting the defrosting operation, by increasing the amount of power supplied to the dew-proof heater of the cooling chamber where the evaporator for defrosting is provided, compared to the amount supplied during cooling, thereby overheating.

4. The cooling device according to claim 3, wherein the control unit is configured to perform the overheating operation based on at least one of the outside air temperature and humidity.

5. The first cooling chamber and the second cooling chamber each include a door and a condensation-preventing heater that suppresses condensation on the door. The cooling device according to claim 1, wherein the condensation prevention heater is configured to switch to the off state based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the on state.

6. A switch unit for the first defrost heater that switches the first defrost heater between the ON state and the OFF state, A switch unit for the second defrost heater that switches between the on state and the off state of the second defrost heater, The system further includes a switch unit for the anti-condensation heater that switches between the on and off states of the anti-condensation heater, The cooling device according to claim 5, wherein the condensation heater switch unit is configured to switch the condensation heater to the off state based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the ON state by at least one of the first defrost heater switch unit and the second defrost heater switch unit.

7. The cooling device according to claim 6, wherein the switch unit for the condensation prevention heater includes an interlocking switch unit that switches the condensation prevention heater between an on state and an off state in conjunction with the first defrost heater switch unit and the second defrost heater switch unit, and an optional switch unit that can switch the condensation prevention heater between an on state and an off state independently of the first defrost heater switch unit and the second defrost heater switch unit.

8. A first evaporator that cools the first cooling chamber by evaporating the refrigerant, A second evaporator is arranged in parallel with the first evaporator and evaporates the refrigerant to cool the second cooling chamber, A common compressor that supplies refrigerant to the first evaporator and the second evaporator, A first defrost heater for defrosting the first evaporator, A second defrost heater for defrosting the second evaporator, A control unit for controlling the common compressor, Doors provided in the first cooling chamber and the second cooling chamber, The door section is equipped with a condensation-preventing heater to suppress condensation, A cooling device configured such that the anti-condensation heater switches to the off state based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the ON state.

9. A switch unit for the first defrost heater that switches the first defrost heater between the ON state and the OFF state, A switch unit for the second defrost heater that switches between the on state and the off state of the second defrost heater, The system further includes a switch unit for the anti-condensation heater that switches between the on and off states of the anti-condensation heater, The cooling device according to claim 8, wherein the condensation heater switch unit is configured to switch the condensation heater to the off state based on the fact that at least one of the first defrost heater and the second defrost heater is switched to the ON state by at least one of the first defrost heater switch unit and the second defrost heater switch unit.

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