JP4660427B2 - Cooling system - Google Patents

Description

  The present invention relates to a cooling device that cools a heating element such as an electronic device on which an integrated circuit element such as a CPU or LSI is mounted to a predetermined temperature.

  In recent years, semiconductor integrated circuit elements such as CPUs and LSIs having a microelectronic circuit in which elements including a large number of semiconductors and internal wirings are combined as a single solid by a special method have come to be widely used. . An integrated circuit device having such a microelectronic circuit generates a large amount of heat during operation. When the temperature of the integrated circuit element rises, a problem that its operation becomes unstable occurs, and when the temperature rises further, the semiconductor is destroyed. Therefore, the heat sink is attached to the integrated circuit element to exchange heat between the heat sink and the air, the heat of the integrated circuit element is released into the air to cool the integrated circuit element, and the integrated circuit elements such as CPU and LSI are hot. It was prevented from causing unstable operation and thermal destruction.

  On the other hand, in a data communication network using a communication line and a computer network (LAN) that performs high-speed data transfer using a facility line within a limited range such as in a building or site, an integrated circuit element as described above is used. A server provided with a large number of electronic devices using the.

That is, in such a server, a significant temperature rise occurs due to the operation of a large number of integrated circuit elements. For example, the server is stored in an electronic device storage furniture as disclosed in Patent Document 1, and is disposed in the electronic device storage furniture. A method of cooling the integrated circuit element by a circulating fan, an air conditioner, or a heat exchanger is employed.
JP 2000-165079 A

  In the conventional electronic equipment storage furniture as described above, the server in which the integrated circuit element is arranged is stored in a rack body that completely blocks the inflow of external air, and the air cooled by the air conditioner or the heat exchanger is stored. The server is cooled to a predetermined temperature by circulating through the main body using a circulation fan.

  However, when cooling the inside of the rack body to a predetermined low temperature, if cool air of a predetermined low temperature is discharged into the rack main body, it is locally cooled by the cold air and dew condensation occurs at the low temperature area. May cause problems. An electronic device such as a server housed in the rack main body may cause a failure if water enters the inside of the rack main body. Therefore, it is necessary to cool the rack main body without causing condensation.

  Therefore, it is necessary to maintain the temperature of the discharged cold air into the main body as high as possible. However, when the discharge cold air temperature is kept high, the outlet temperature of the evaporator constituting the air conditioner may be too low due to the load fluctuation of the server accommodated therein. In this case, the refrigerant does not completely evaporate inside the evaporator, and a phenomenon of liquid return returning to the compressor in a state where the liquid content is large occurs. As described above, when the liquid refrigerant is sucked into the compressor, the compressor may be broken.

  Therefore, it is possible to control the operation of the compressor by following the load fluctuation of the electronic equipment such as a server, and it is possible to control the operation of the compressor by an inverter. However, the inverter-type compressor is expensive. Therefore, there is a problem that the cost of the product itself rises, and without using an inverter type compressor, it is possible to avoid liquid return to the compressor while maintaining the outlet temperature of the evaporator at a predetermined temperature or higher. Development of a cooling device that can be used has been desired.

  The present invention has been made in order to solve the conventional technical problem, and allows the outlet temperature of the evaporator to be maintained at a predetermined temperature or higher so as not to cause dew condensation on the heating element accommodated therein. And the cooling device which can avoid the liquid return to a compressor is provided.

  The cooling device of the present invention includes a storage chamber for storing a heating element, and a cooling unit in which a refrigerant circuit is configured by a compressor, a condenser, an expansion valve, an evaporator, and the like. The heating element is cooled by being circulated in the storage chamber, and includes a control device that controls the valve opening of the expansion valve and controls the operation of the compressor based on the air temperature in the storage chamber. The control device has an evaporation temperature control mode for controlling the opening degree of the expansion valve based on the evaporation temperature of the refrigerant in the evaporator so that the evaporation temperature becomes a predetermined condensation avoidance temperature that can avoid condensation on the heating element. And when the superheat degree of the refrigerant in the evaporator falls below a predetermined liquid return risk value, the expansion valve is set so that the superheat degree becomes a predetermined liquid return avoidance value based on the superheat degree of the refrigerant in the evaporator. Control valve opening of Characterized in that switching to that superheat control mode.

  According to a second aspect of the present invention, there is provided the cooling device according to the above invention, wherein, in the superheat degree control mode, the control device determines the evaporation temperature when the evaporation temperature rises to a predetermined upper limit temperature based on the evaporation temperature of the refrigerant in the evaporator. It is characterized by returning to the control mode.

  According to a third aspect of the present invention, there is provided the cooling device according to the above invention, wherein the control device evaporates when the evaporation temperature is reduced to a predetermined lower limit temperature in the superheat degree control mode based on the evaporation temperature of the refrigerant in the evaporator. It is characterized by returning to the temperature control mode.

  According to a fourth aspect of the present invention, there is provided a cooling device according to any one of the above-mentioned inventions, wherein the control device operates the compressor so as to obtain a predetermined air temperature based on the air temperature in the storage chamber without controlling the rotational speed of the compressor. The stop is controlled.

  According to the present invention, a storage chamber that stores a heating element, and a cooling unit in which a refrigerant circuit is configured by a compressor, a condenser, an expansion valve, an evaporator, and the like are provided. A cooling device that cools the heating element by circulating in the storage chamber, and includes a control device that controls the valve opening of the expansion valve and controls the operation of the compressor based on the air temperature in the storage chamber, The control device has an evaporation temperature control mode for controlling the opening degree of the expansion valve based on the evaporation temperature of the refrigerant in the evaporator so that the evaporation temperature becomes a predetermined condensation avoidance temperature that can avoid condensation on the heating element. Since it performs, it becomes possible to cool the said heat generating body, avoiding the dew condensation to a heat generating body reliably.

  As a result, even if the heating element is, for example, an electronic device or the like provided with an integrated circuit element, condensation of the electronic device or the like may occur due to the operation of the cooling device, thereby avoiding inconvenience that may cause a failure. In addition, it is possible to cool to a predetermined temperature, and it is possible to reliably or effectively eliminate inconvenience that the heating element itself becomes unstable due to high temperature and inconvenience due to thermal destruction.

  In addition to the above, when the degree of superheat of the refrigerant in the evaporator is reduced below a predetermined liquid return risk value, the control device for the cooling device of the present invention is based on the degree of superheat of the refrigerant in the evaporator. Since the refrigerant is not fully evaporated in the evaporator, the refrigerant in a state where there is a large amount of liquid Thus, it is possible to effectively avoid the phenomenon of liquid return returning to the compressor, and it is possible to effectively avoid failure of the compressor due to the liquid return.

  According to a second aspect of the present invention, in the above invention, in the superheat degree control mode, the control device evaporates when the evaporation temperature rises to a predetermined upper limit temperature based on the evaporation temperature of the refrigerant in the evaporator. Since the temperature control mode is restored, the heating element can be effectively cooled.

  In particular, when the evaporation temperature of the refrigerant in the evaporator rises to a predetermined upper limit temperature, the refrigerant can be effectively evaporated in the evaporator, and the degree of superheat of the refrigerant in the evaporator increases. There is almost no liquid return phenomenon in which the refrigerant with a large amount of water returns to the compressor. Accordingly, it is possible to cool the heating element to a predetermined temperature without causing condensation on the heating element while avoiding the occurrence of liquid return as described above.

  According to the invention of claim 3, in each of the above inventions, in the superheat degree control mode, when the evaporation temperature is reduced to a predetermined lower limit temperature based on the evaporation temperature of the refrigerant in the evaporator, the control device In order to return to the control mode, the opening degree of the expansion valve is controlled based on the temperature of the evaporator, and the operation of the compressor can be stopped based on the air temperature in the storage chamber.

  Therefore, when the evaporation temperature of the refrigerant in the evaporator is lowered to a predetermined lower limit temperature, the load on the evaporator is reduced, so the degree of superheat is also reduced. For this reason, the liquid easily returns to the compressor, but in this state, the storage chamber that houses the heating element is likely to be sufficiently cooled to a predetermined temperature or less, and the control device Since the operation of the compressor is stopped based on the temperature of the compressor, the liquid return to the compressor does not occur.

  This makes it possible to stop the operation of the compressor before the temperature in the storage room containing the heating element becomes lower than the temperature at which condensation is likely to occur, and to avoid liquid return to the compressor in advance. Is possible.

  According to the invention of claim 4, in each of the above-mentioned inventions, the control device operates / stops the compressor so as to obtain a predetermined air temperature based on the air temperature in the storage chamber without controlling the rotation speed of the compressor. By controlling the above, for example, the inventions described above can be realized without using an inverter type compressor capable of controlling the rotation speed of the compressor, and the cost of the cooling device itself can be reduced. It becomes possible.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view of a cooling device 1 to which the present invention is applied, FIG. 2 is a longitudinal side view of the cooling device 1, and FIG. 3 is a view for explaining the flow of cold air in the cooling device 1.

  The cooling device 1 according to the present embodiment is a device for cooling a heating element such as a server 2 serving as a center for providing various services to a computer connected to a network. The heating element is limited to the server 2. It is not intended to generate heat but is itself suitable for cooling those that generate malfunctions or malfunctions due to the generated heat, and that do not like the penetration of condensed water or the like. Note that this embodiment is intended for cooling a single or a plurality of servers 2 having a circuit board on which a plurality of semiconductor integrated circuit elements such as LSIs and CPUs are mounted as heating elements.

  The cooling device 1 has a main body constituted by a cabinet 3 that opens to the front and rear surfaces. In addition, since the cabinet 3 in this embodiment sets the cooling set temperature of the server 2 to be cooled to about + 30 ° C., in particular, it has heat insulation in consideration of heat dissipation efficiency in relation to the outside air temperature. It is not necessary.

  A storage chamber 4 that opens to the front and rear surfaces is formed in the cabinet 3, and a plurality of servers 2... Can be stored in the storage chamber 4 in the vertical direction. In the storage chamber 4, for example, columns (not shown) are erected on the left and right inner walls, and each server 2 can be independently fixed to the columns by screws or the like. The front and rear openings of the storage chamber 4 are openable and closable by a front door 5 and a rear door 6 (not shown in FIG. 1, only shown in FIG. 2) provided with glass that can be seen through the inside. Is blocked. The doors 5 and 6 may be provided with a locking mechanism for safety management such that the server 2 or the like housed inside cannot be operated by a person other than the administrator.

  A pedestal angle 7 having a predetermined height is attached to the bottom surface of the cabinet 3, and both side surfaces of the pedestal angle 7 are covered with a decorative panel 8 together with both side surfaces of the cabinet 3. Thereby, a machine room 9 is formed below the cabinet 3. A pair of fixing members 10 are attached to the front and rear lower sides of the base leg angle 7 that fixes the bottom of the machine room 9. In addition, on the bottom wall 3 </ b> A of the cabinet 3, a cold air discharge port 12 and a cold air suction port 11 penetrating vertically are formed in the front and rear, respectively.

  On the bottom surface of the bottom wall 3 </ b> A of the cabinet 3 that becomes the ceiling of the machine room 9, a heat-insulating cooling box 14 having an opening on the top surface is provided in contact. A cooling chamber 15 is formed inside the cooling box 14, and an evaporator 16 constituting a cooling unit R together with a compressor 22 to be described later, and a cool air circulation fan 17 is disposed on the cool air outflow side of the evaporator 16. The A cooling air discharge port 19 and a cold air suction port 18 on the cooling box 14 side are formed in the upper surface opening of the cooling box 14 by a partition plate (not shown). The cold air outlet 19 and the cold air inlet 18 respectively correspond to the cold air outlet 12 and the cold air inlet 11 formed in the bottom wall 3 </ b> A of the cabinet 3. In addition, a sealing material (not shown) is attached to the opening edge of the cooling box 14 so as to come into close contact with the lower surface of the bottom wall 3 </ b> A of the cabinet 3.

  On the other hand, a front duct 27 is formed between the front door 5 constituting the front surface of the cabinet 3 and the front wall of each server 2 accommodated in the storage chamber 4 with a predetermined interval. The cool air discharged by the cool air circulation fan 17 from the cool air discharge port 12 formed in the bottom wall 3A rises up the front duct 27. Thereby, cold air is efficiently supplied into the storage chamber 4.

  Further, a vent hole (not shown) is formed on the front surface of each server 2, and a blower 2 </ b> A that sucks air from the front surface and discharges air to the rear is attached to the vent hole. The blowers 2A of each server 2 can be controlled independently of each other, and when the blower 2A is operated, the cool air rising through the front duct 27 is passed through the server 2 where the blower 2A is provided. Is possible.

  Therefore, in the cooling device 1, the cool air discharged from the inside of the cooling chamber 15 passes through each server 2 by the operation of each blower 2A while ascending the front duct 27 as shown in FIG. After being discharged from the rear of the cabinet 3, a cool air circulation fan is provided in a cooling chamber 15 that flows between the rear door 6 constituting the back of the cabinet 3 and the back of each server 2 and is formed below the cabinet 3. 17 returns to the cooling chamber 15 through the cold air inlets 11 and 18. Thereby, the server 2 as a heat generating body accommodated in the storage chamber 4 is cooled. In this embodiment, it is assumed that the internal temperature sensor 32 as a means for detecting the temperature in the storage chamber 4 is attached in the vicinity of the cold air inlet 11 located on the storage chamber 4 side.

  On the other hand, a mounting base 21 that forms the bottom of the cooling unit R is housed in the machine room 9. The mounting base 21 includes a compressor 22 that forms an annular refrigerant circuit together with the evaporator 16, a condenser. A fan 23, a condenser blower 24, a control box 25, and the like are provided. Casters 21 </ b> A are attached to the four corners of the lower surface of the mounting base 21. An openable / closable panel 26 is attached to the front surface of the machine room 9 to conceal the machine room 9. The panel 26 has a plurality of air holes (not shown) corresponding to the front of the condenser 23.

  Here, the evaporator 16 in the cooling box 14 includes the compressor 22, the condenser 23, and the electronic expansion, as shown in the refrigerant circuit diagram of FIG. A refrigerant circuit 29 is formed by sequentially connecting the valve (expansion valve) 28 and the evaporator 16 in an annular manner. A predetermined amount of refrigerant is sealed in the refrigerant circuit 29. Thereby, a well-known refrigerant circuit is comprised.

  Further, an evaporator inlet temperature sensor 30 and an evaporator outlet temperature sensor 31 for detecting the respective refrigerant temperatures are provided on the refrigerant inlet side and the refrigerant outlet side of the evaporator 16. In the present embodiment, the temperature on the refrigerant inlet side of the evaporator 16 is the evaporation temperature of the refrigerant in the evaporator 16. Further, the difference between the evaporator inlet temperature and the evaporator outlet temperature (evaporator outlet temperature−evaporator inlet temperature) represents the degree of superheat. That the degree of superheat is large means that the refrigerant is well evaporated in the evaporator 16 by the amount of the degree of superheat and the load is large. In addition, the fact that the degree of superheat is small means that the refrigerant is not so much evaporated in the evaporator 16 and the load is small.

  The electronic expansion valve 28 controls the flow rate of the refrigerant flowing in the refrigerant circuit 29 to depressurize the condensed refrigerant, and opens the valve according to the cooling load, that is, the degree of superheat in the evaporator 16 as described above. The degree is adjusted.

  Further, the compressor 22 in the present embodiment is not an inverter-type compressor that can control the rotation speed exceptionally, but is based on the air temperature in the storage chamber 4, that is, the internal temperature, by the control device C described later. This is a constant speed compressor capable of controlling operation-stop by ON-OFF control.

  Note that the condenser 23 in the present embodiment is provided with an outside air temperature sensor 33 for detecting the temperature of the outside air sucked into the machine room 9 by the condenser fan 24.

  Next, with reference to the electric block diagram of FIG. 5, the control apparatus C which controls the cooling device 1 in a present Example is demonstrated. The control device C is composed of a general-purpose microcomputer, and on the input side, an evaporator inlet temperature sensor 30 for detecting the refrigerant inlet temperature of the evaporator 16 (evaporation temperature of the refrigerant in the evaporator), and the evaporator 16. An evaporator outlet temperature sensor 31 for detecting the refrigerant outlet temperature, an internal temperature sensor 32 for detecting the temperature in the storage chamber 4, and an outside air temperature sensor 33 for detecting the outside air temperature are connected. Moreover, the electronic expansion valve 28, the compressor 22, the cool air circulation fan 17, and the condenser blower 24 are connected to the output side. It is assumed that a control panel (not shown) is connected to the input side of the control device C.

  Here, the compressor 22 in the present embodiment is a constant speed compressor as described above, and is connected in parallel to the AC power source 35 together with the condenser blower 24, and ON / OFF control based on the output from the control device C. The switch 36 is controlled. Thereby, based on the output from the control apparatus C, the compressor 22 and the condenser blower 24 are operated and controlled in synchronization. On the other hand, the cold air circulation fan 17 provided in the cooling chamber 15 is connected via an inverter 37. Therefore, based on the output from the control device C, the cool air circulation fan 17 is subjected to rotation speed control independently of the compressor 22 and the like.

  With the above configuration, when the operation of the cooling device 1 is started by operating the control panel, the control device C outputs the output of the internal temperature sensor 32, the evaporator inlet temperature sensor 30, and the evaporator outlet temperature sensor. Based on the output of 31, the compressor 22, the condenser blower 24, and the cool air circulation fan 14 are controlled.

  Specifically, the cooling device 1 in the present embodiment accommodates a server 2 as a heating element in a storage chamber 4, and efficiently cools the heat generated from the server 2 to the server 2. In order to prevent the occurrence of dew condensation, the cooling set temperature in the storage chamber 4 is assumed to be + 30 ° C., for example.

  Therefore, the control device C operates the compressor 22 and the condenser blower 24 when the temperature in the storage chamber 4 detects a predetermined upper limit temperature, for example, + 33 ° C., based on the output of the internal temperature sensor 32. When a predetermined lower limit temperature, for example, + 27 ° C. is detected, the operation of the compressor 22 and the condenser blower 24 is stopped. Thereby, the inside of the storage chamber 4 can be maintained at a temperature around + 30 ° C.

  The control device C performs electronic control based on the temperatures of the temperature sensors 30 and 31 provided on the refrigerant inlet side and the outlet side of the evaporator 16 and the degree of superheat in the evaporator 16 calculated based on the temperature sensors 30 and 31. The expansion valve 28 is controlled.

  Hereinafter, description will be given with reference to the flowchart of FIG. In step S1, the control device C calculates the superheat degree by calculating the difference between the evaporator inlet temperature, that is, the refrigerant evaporation temperature in the evaporator 16 and the evaporator outlet temperature, based on the temperature sensors 30 and 31. In this embodiment, it is determined whether or not the degree of superheat is greater than 7 deg as the liquid return risk value.

  The liquid return risk value is a state in which the refrigerant is not sufficiently evaporated in the evaporator 16, and a so-called liquid return phenomenon in which a refrigerant with a large amount of liquid is sucked into the compressor 22 can be avoided. The degree of superheat is referred to as 7 deg in this embodiment, but is not limited to this.

  When the degree of superheat is greater than the liquid return risk value, the control device C determines that the refrigerant is well evaporated in the evaporator 16 and the possibility of liquid return is low, and proceeds to step S2 to evaporate. Execute temperature control mode.

  In this evaporation temperature control mode, the temperature of the refrigerant at the evaporator 16, that is, the evaporation temperature of the refrigerant in the evaporator 16 is maintained at a predetermined dew condensation avoiding temperature, in this embodiment + 12 ° C. Control the opening. In this embodiment, the condensation avoidance temperature is maintained at + 12 ° C., but is not limited to this. For example, + 11 ° C. ≦ evaporator inlet temperature ≦ + 13 ° C. It shall be good. In addition, after completion of step S2, control device C returns to step S1 again and determines whether or not the degree of superheat is greater than a predetermined liquid return risk value.

  Thus, in the evaporation temperature control mode, the refrigerant is stored in the evaporator 16 from the cooling chamber 15 in which the evaporator 16 is disposed by maintaining the evaporation temperature of the refrigerant at a temperature higher than a predetermined dew condensation avoiding temperature. It is possible to cool the server 2 while effectively avoiding the inconvenience that dew condensation occurs in the server 2 or the like as a heating element in the storage chamber 4 due to a marked decrease in the temperature of the cool air discharged into the chamber 4. It becomes possible. Therefore, the operation of the cooling device 1 makes it possible to avoid the inconvenience that causes condensation on the server 2 as a heating element and causes a failure.

  Further, for example, the air heated to about + 40 ° C. by the heat generated by the server 2 as a heating element and sucked into the cooling chamber 15 through the cold air inlets 11 and 18 is, for example, about + 20 ° C. by the evaporator 16. It is possible to cool and discharge into the storage chamber 4 through the cold air discharge ports 12 and 19. As a result, the inside of the storage chamber 4 can be cooled to a predetermined temperature, that is, around + 30 ° C. in this embodiment, so that the server 2 itself becomes unstable due to high temperature and the disadvantage due to thermal destruction. It is possible to solve the problem reliably or effectively.

  As described above, the heating element is not limited to the server 2, and as long as the heating element itself generates heat and needs to be cooled, and there is a risk of causing deterioration or failure due to condensed water, The present invention is particularly effective.

  On the other hand, by executing the evaporation temperature control mode as described above, the inside of the storage chamber 4 is cooled to some extent, so that the cooling load in the evaporator 16 is reduced, and in step S1, the degree of superheat is a predetermined liquid return risk value, In this example, when it becomes smaller than 7 deg, control device C shifts to superheat degree control mode of Step S3.

  In this superheat degree control mode, the opening degree of the electronic expansion valve 28 is controlled so that the superheat degree is a liquid return avoidance value larger than the liquid return risk value, and in this mode, 10 degrees. Also in this case, the liquid return avoidance value is not limited to 10 deg, and may be a certain range such as 7 deg <superheat ≦ 10 deg. The difference between the liquid return risk value and the liquid return avoidance value is 3 deg in this embodiment, but is not limited to this. For example, the opening degree of the electronic expansion valve 28 may be controlled so that the degree of superheat is less than 7 deg in the superheat degree control mode.

  Thereby, the control device C shifts to the superheat degree control mode when the difference between the evaporation temperature of the refrigerant in the evaporator 16 and the outlet temperature, that is, when the superheat degree falls below a predetermined liquid return risk value, Since the opening degree of the electronic expansion valve 28 is controlled based on the degree of superheat of the refrigerant in the evaporator 16 so that the degree of superheat maintains a predetermined liquid return avoidance value, the refrigerant does not evaporate inside the evaporator 16. As a result, it is possible to effectively avoid the phenomenon of liquid return in which the refrigerant with a high liquid content returns to the compressor 22, and it is possible to effectively avoid failure of the compressor 22 due to the liquid return. It becomes.

  Thereafter, the control device C proceeds to step S4, and in the superheat degree control mode, the refrigerant inlet temperature of the evaporator 16, that is, the refrigerant evaporation temperature detected by the evaporator inlet temperature sensor 30, is a predetermined upper limit temperature, For example, it is determined whether or not the temperature has risen above + 14 ° C., and further whether or not the temperature has fallen below a predetermined lower limit temperature, eg, + 8 ° C. If none of these apply, the process returns to step S3 and the superheat degree control mode is executed.

  On the other hand, when the evaporation temperature of the refrigerant in the evaporator 16 rises above a predetermined upper limit temperature, which is + 14 ° C. in this embodiment, the control device C proceeds to step S2 and returns to the evaporation temperature control mode.

  That is, when the evaporation temperature in the evaporator 16 rises above a predetermined upper limit temperature, the refrigerant can be effectively evaporated in the evaporator 16, so the degree of superheat of the refrigerant in the evaporator 16 increases. For this reason, the phenomenon of liquid return in which the refrigerant having a large amount of liquid returns to the compressor is hardly observed. Accordingly, in the superheat degree control mode, when the evaporation temperature of the refrigerant in the evaporator 16 rises higher than the predetermined upper limit temperature, by returning to the evaporation temperature control mode, avoiding the occurrence of liquid return as described above, The server 2 can be effectively cooled to a predetermined temperature without causing condensation on the server 2 as a heating element.

  In step S4, when the evaporation temperature of the refrigerant in the evaporator 16 is lower than a predetermined lower limit temperature, which is + 8 ° C. in the present embodiment, the control device C proceeds to step S2 and proceeds to the evaporation temperature control mode. Return to.

  That is, when the evaporation temperature in the evaporator 16 falls below a predetermined lower limit temperature, the load on the evaporator 16 is reduced, and the degree of superheat is also reduced. Therefore, the liquid easily returns to the compressor 22, but in this state, there is a possibility that the inside of the storage chamber 4 that houses the server 2 as a heating element is sufficiently cooled to a predetermined temperature or lower. high. Therefore, when the evaporation temperature of the refrigerant in the evaporator 16 is lower than a predetermined lower limit temperature, the control device C returns to the evaporation temperature control mode, so that the expansion valve 28 is based on the temperature of the evaporator 16. In this case, since the temperature in the storage chamber 4 is likely to be + 27 ° C. or less, the compressor 22 is operated by the output of the internal temperature sensor 32. It will be stopped. Therefore, liquid return to the compressor 22 does not occur.

  As a result, the operation of the compressor 22 can be stopped before the temperature in the storage chamber 4 that houses the server 2 serving as a heating element becomes lower than the temperature at which condensation is likely to occur. Liquid return can be avoided in advance.

  Accordingly, even when the server 2 in which the integrated circuit element is disposed as a heating element in the storage chamber 4 and other electrical devices, for example, are stored, the temperature is low enough to prevent condensation as in the present invention. By discharging air into the storage chamber 4, it is possible to avoid the inconvenience that the inside of the storage chamber 4 is locally cooled and dew condensation occurs, and the device or the like breaks down. It becomes possible to do. Moreover, since the inside of the storage chamber 4 can be cooled at a low temperature at which condensation does not occur, it is possible to prevent unstable operation or thermal destruction of the server 2 or the like due to a high temperature.

  Further, in the present invention, control is performed to maintain the superheat degree at a predetermined liquid return avoidance value in the superheat degree control mode while maintaining the temperature of the discharged cold air into the storage chamber 4 as high as possible. As a result, the refrigerant does not evaporate, and a liquid return phenomenon that returns to the compressor 22 in a state where the liquid content is large is generated, so that it is possible to avoid inconvenience that may cause the compressor 22 to malfunction.

  Therefore, even when the heat load by the heating element such as the server 2 accommodated in the storage chamber 4 fluctuates greatly, the refrigerant evaporation temperature in the evaporator 16 (in this embodiment, the evaporator inlet temperature sensor) is quickly detected. 30), and by controlling the degree of opening of the electronic expansion valve 28 based on the degree of superheat, heat is effectively generated without causing condensation and returning liquid to the compressor 22. It becomes possible to cool the body.

  In this embodiment, when the upper limit temperature is exceeded or when the temperature is lower than the lower limit temperature, the evaporating temperature control mode is restored. However, the present invention is not limited to this, and the upper limit temperature and the lower limit temperature are not limited thereto. It is also possible to return to the evaporation temperature control mode when the temperature is reached.

  Further, in this embodiment, the constant speed compressor 22 is controlled to be turned on and off based on the air temperature in the storage chamber 4, and the opening of the expansion valve 28 is controlled by the evaporation temperature of the refrigerant in the evaporator 16 and the degree of superheat. By controlling, the inside of the storage chamber 4 is cooled to a predetermined temperature, and it is possible to effectively avoid the occurrence of condensation and the return of liquid to the compressor. As a result, the cost can be reduced.

  Even in the case of a cooling device equipped with an inverter type compressor, even if the inverter fails and rotation speed control cannot be performed, by using the present invention, dew condensation can occur. Occurrence and liquid return to the compressor can be effectively avoided.

It is a front view of the cooling device to which this invention is applied. It is a vertical side view of a cooling device. It is explanatory drawing of the flow of the cold air of a cooling device. It is a refrigerant circuit figure of a cooling device. It is an electrical block diagram of a cooling device. It is a flowchart figure of cooling control.

Explanation of symbols

R Cooling unit 1 Cooling device 2 Server (heating element)
2A Blower 3 Cabinet 4 Storage room 5 Front door 6 Rear door 9 Machine room 11 Cold air inlet (cabinet side)
12 Cold air outlet (cabinet side)
14 Cooling box 15 Cooling chamber 16 Evaporator 17 Cooling air circulation fan 18 Cooling air inlet (cooling box side)
19 Cold air outlet (cooling box side)
22 Compressor 23 Condenser 24 Condenser Blower 28 Electronic Expansion Valve (Expansion Valve)
30 Evaporator inlet temperature sensor 31 Evaporator outlet temperature sensor 32 Inside temperature sensor 33 Outside air temperature sensor

Claims (4)

A storage chamber for storing a heating element, and a cooling unit having a refrigerant circuit composed of a compressor, a condenser, an expansion valve, an evaporator, and the like, and cool air exchanged with the evaporator is circulated into the storage chamber by a blower A cooling device for cooling the heating element,
A control device for controlling the valve opening of the expansion valve and controlling the operation of the compressor based on the air temperature in the storage chamber;
The control device controls an opening temperature of the expansion valve based on an evaporation temperature of the refrigerant in the evaporator so that the evaporation temperature becomes a predetermined condensation avoidance temperature capable of avoiding condensation on the heating element. When the control mode is executed and the superheat degree of the refrigerant in the evaporator decreases below a predetermined liquid return risk value, the superheat degree is set to a predetermined liquid return avoidance value based on the superheat degree of the refrigerant in the evaporator. The cooling device is switched to a superheat degree control mode for controlling the valve opening degree of the expansion valve so that   In the superheat degree control mode, the control device returns to the evaporation temperature control mode when the evaporation temperature rises to a predetermined upper limit temperature based on the evaporation temperature of the refrigerant in the evaporator. The cooling device according to claim 1.   In the superheat degree control mode, the control device returns to the evaporation temperature control mode when the evaporation temperature decreases to a predetermined lower limit temperature based on the evaporation temperature of the refrigerant in the evaporator. The cooling device according to claim 1 or 2.   The said control apparatus controls the operation-stop of the said compressor so that it may become predetermined air temperature based on the air temperature in the said storage chamber, without controlling the rotation speed of the said compressor. The cooling device according to any one of claims 1 to 3.

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