JP2007139276A - Cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system capable of reducing running costs, and capable of preventing insufficient lubrication and failure of a compressor without deteriorating cooling efficiency even when an outside air temperature is high such as in midsummer. <P>SOLUTION: In the cooling system, since a refrigerant with a lowered temperature can be sent into a condenser 11 in the compressor 10, even when the outside air temperature is high such as in midsummer, the refrigerant can be positively condensed in the condenser 11, and deterioration of cooling efficiency can be prevented. Since the refrigerant and oil can be cooled without using water or the like, running costs can be reduced. Since the oil can be returned to a suction side of the compressor 10 while controlling a flow rate of the oil passing through a bypass passage 30 by adjusting the opening of a flow control valve 33, insufficient lubrication and failure of the compressor 10 can be positively prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling system used for indoor air conditioning, a refrigerator / refrigerator, a refrigerated showcase, and the like.

  For example, a cooling system 50 shown in FIG. 8 is known as this type of cooling system. The cooling system 50 includes a refrigeration circuit including a compressor 51, a condenser 52, an expansion valve 53, and an evaporator 54, and employs an air cooling system that cools the condenser 52 using outside air.

  However, in the cooling system 50, for example, when the outside air temperature is high such as midsummer, the condenser 52 may not be sufficiently cooled by the outside air. Thus, for example, when the outside air temperature is high, such as midsummer, when the high-temperature and high-pressure refrigerant discharged from the compressor 51 cannot be completely condensed by the condenser 52, the cooling efficiency of the cooling system 50 decreases.

  In order to solve such a problem, a cooling system 60 shown in FIG. 9, a cooling system 70 shown in FIG. 10, a cooling system 80 shown in FIG. 11, and a cooling system 85 shown in FIG. 12 are known.

  The cooling system 60 shown in FIG. 9 is provided with a pipe 61 a that circulates water around the compressor 61, thereby cooling the main body of the compressor 61, and supplying a cooled refrigerant to the condenser 52 for cooling efficiency. It is intended to prevent the decrease of.

  The cooling system 70 shown in FIG. 10 uses a condenser 72 composed of a double-pipe heat exchanger and cools the condenser 72 with water, so that the refrigerant temperature in the condenser 72 is not affected by the outside air temperature. As a result, the cooling efficiency is prevented from lowering.

  Furthermore, the cooling system 80 shown in FIG. 11 includes a liquid injection circuit 81 for returning the refrigerant having a low temperature in the condenser 52 to the compressor 51. As a result, the cooling system 80 returns the low-temperature refrigerant to the compressor 51 through the liquid injection circuit 81 to lower the refrigerant temperature in the compressor 51, and supplies this low-temperature refrigerant to the condenser 52 for cooling efficiency. To prevent the loss of

  The cooling system 85 shown in FIG. 12 separates the refrigerant and the oil by the oil separator 86, then cools the separated oil by the oil cooler 87, and returns the low temperature oil to the compressor 51. 88. As a result, the cooling system 85 returns the low temperature oil to the compressor 51 through the oil injection circuit 88 to lower the refrigerant temperature in the compressor 51, and supplies the low temperature refrigerant to the condenser 52 to reduce the cooling efficiency. To prevent the loss of

Furthermore, conventionally, the refrigerant generally used in the cooling system has been chlorofluorocarbon. However, since chlorofluorocarbon has a problem of destroying the ozone layer surrounding the earth, in recent years, as an alternative refrigerant to chlorofluorocarbon, ammonia or the like is used. A cooling system 90 shown in FIG. 13 using a natural refrigerant is known (for example, see Patent Document 1). The cooling system 90 includes a compressor 91, a condenser 92, an expansion valve 93, an evaporator 94, and an oil separator 95, and ammonia that is a refrigerant and oil that flows out of the compressor 91 are separated by the oil separator 95. The oil is repeatedly used by returning the separated oil to the compressor 91.
JP 2000-274845 A JP-A-6-241585

  However, since the cooling system 60 and the cooling system 70 configured as described above require a large amount of water, the running cost becomes high. Further, in the cooling system 80, a part of the refrigerant is returned to the compressor 51, so that the cooling efficiency of the cooling system 80 is reduced, or the oil in the compressor 51 is poured out by the liquid refrigerant returned to the compressor 51. As a result, the compressor 51 may be poorly lubricated. In the cooling system 85, the flow rate of the oil flowing through the oil injection circuit 88 changes based on the pressure of the refrigerant / oil mixture immediately after being discharged from the compressor 51 and the oil temperature immediately after being separated by the oil separator 86, For example, when a large amount of oil returns to the compressor 51, the compressor 51 may break down. Furthermore, in the cooling system 90, since the high-temperature oil immediately after flowing out of the compressor 91 is returned to the compressor 91, the refrigerant temperature increases with the temperature inside the compressor 91, and the cooling efficiency may be reduced. .

  The present invention has been made in view of the above circumstances, and its object is to reduce the running cost without lowering the cooling efficiency even when the outside air temperature is high, such as midsummer. It is another object of the present invention to provide a cooling system that can prevent poor lubrication and failure of the compressor.

  In order to achieve the above object, a cooling system of the present invention is provided between a compressor and a condenser in a cooling system including a refrigeration circuit including a compressor, a condenser, an expansion means, and an evaporator. An oil separator that separates oil contained in the refrigerant discharged from the machine from the refrigerant, a bypass passage that returns the oil separated by the oil separator to the suction side of the compressor, and an oil cooler that cools the oil passing through the bypass passage And an oil return amount control means for controlling the flow rate of oil passing through the bypass flow path.

  According to the cooling system of the present invention, the refrigerant and the oil are separated in the oil separator, and the separated oil is cooled by the oil cooler when passing through the bypass passage. Then, the low-temperature oil is caused to flow into the suction side of the compressor while the flow rate of the oil returning to the compressor is controlled by the oil return amount control means. When the low-temperature oil returns to the compressor, the refrigerant temperature in the compressor is lowered, and the refrigerant having the lowered temperature is supplied to the condenser.

  According to the cooling system of the present invention, the refrigerant whose temperature has decreased in the compressor can be caused to flow into the condenser. For example, even if the outside air temperature is high, such as midsummer, the refrigerant is reliably condensed in the condenser. It is possible to prevent a decrease in the cooling efficiency of the cooling system. At that time, since the refrigerant can be cooled without using water or the like, the running cost can be reduced. Further, the cooling system of the present invention can return the oil cooled by the oil cooler to the compressor while returning the oil flow rate to the compressor while controlling the oil flow rate by the oil return amount control means. The oil in the machine can always be kept at a predetermined amount, and the lubrication failure and failure of the compressor can be surely prevented.

  1 to 3 show a cooling system according to a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram of the cooling system, FIG. 2 is a flowchart showing control of the cooling system, and FIG. 3 is a high pressure of the cooling system. It is a figure which shows the relationship between a side pressure and an oil return amount.

  The cooling system shown in FIG. 1 includes a compressor 10, a condenser 11, a refrigeration circuit including an expansion valve 12 and an evaporator 13 as expansion means, an oil separator 20, a bypass flow path 30, and an oil cooler 31. ing. The cooling system includes a pressure detector 15 that detects the pressure P of the refrigerant / oil mixture immediately after being discharged from the compressor 10, and an oil temperature detector 16 that detects the oil temperature T immediately after separation in the oil separator 20. Have In this cooling system, the refrigerant can be circulated in the order of the compressor 10 → the oil separator 20 → the condenser 11 → the expansion valve 12 → the evaporator 13 → the compressor 10, and the oil flowing out of the compressor 10 together with the refrigerant can be circulated. The compressor 10, the oil separator 20, the oil cooler 31, and the compressor 10 can be circulated in this order. At this time, the refrigerant and oil circulate at a high pressure through the compressor 10 → the oil separator 20 → the condenser 11 → the expansion valve 12 (hereinafter referred to as the high pressure side), and the expansion valve 12 → the evaporator 13 → the compressor 10 is lowered. Circulating with pressure (hereinafter referred to as the low pressure side). The refrigerant used in the cooling system is a natural refrigerant (for example, ammonia).

  The condenser 11 employs an air cooling system that cools using outside air.

  The oil separator 20 is provided between the compressor 10 and the condenser 11 and separates oil contained in the refrigerant discharged from the compressor 10 from the refrigerant.

  The bypass channel 30 is for returning the oil separated in the oil separator 20 to the suction side of the compressor 10, and connects the oil separator 20 and the compressor 10. The bypass flow path 30 includes an electromagnetic valve 32 and a flow rate control valve 33.

  The oil cooler 31 is for cooling the oil passing through the bypass passage 30 and is provided between the oil separator 20 and the compressor 10. The oil cooler 31 employs an air-cooling type that cools using outside air.

  The solenoid valve 32 is disposed between the oil cooler 31 and the compressor 10. The electromagnetic valve 32 is open when the compressor 10 is in operation, and is closed when the compressor 10 is stopped. That is, the solenoid valve 32 returns the cooled oil to the suction side of the compressor 10 when the compressor 10 is in operation, and stops the oil from returning when the compressor 10 is stopped.

  The flow control valve 33 is disposed between the oil cooler 31 and the compressor 10. The flow control valve 33 is connected to the controller 40 and constitutes an oil return amount control means. Further, the controller 40 adjusts the opening degree of the flow control valve 33 based on the oil temperature T detected by the oil temperature detector 16 and the high pressure side pressure P detected by the pressure detector 15, and the oil passing through the bypass passage 30. The flow rate is controlled. By adjusting the opening degree of the flow rate control valve 33 and controlling the flow rate of oil passing through the bypass flow path 30, the oil return amount to the compressor 10 is increased or decreased. As the flow control valve 33, for example, a stepping motor drive type proportional control valve is employed.

  Here, the relationship between the opening degree of the flow control valve 33 and the oil temperature T will be described. For example, when the outside air temperature is low, such as in winter, the oil temperature T detected by the oil temperature detector 16 is also low, so that the viscosity of the oil increases and the amount of oil returned to the compressor 10 may be lower than the set amount. is there. Therefore, in order to suppress a decrease in the amount of oil returned to the compressor 10, the controller 40 is adjusted so that the opening degree of the flow rate control valve 33 is increased so that the oil flow rate through the bypass passage 30 increases. Control. By controlling the flow rate of the oil passing through the bypass flow path 30, the set amount of oil returns to the compressor 10, so that a decrease in the amount of oil returned to the compressor 10 is suppressed. On the other hand, when the outside air temperature is high, for example, in summer, the oil temperature T detected by the oil temperature detector 16 is also high, so the viscosity of the oil is low and the oil return amount to the compressor 10 is higher than the set amount. There is a fear. Therefore, in order to suppress an increase in the amount of oil returned to the compressor 10, the controller 40 adjusts the opening degree of the flow rate control valve 33 to be small so that the oil flow rate through the bypass passage 30 decreases. Control. By controlling the flow rate of the oil passing through the bypass flow path 30, a set amount of oil returns to the compressor 10, so that an increase in the amount of oil returned to the compressor 10 is suppressed.

  A relationship between the opening degree of the flow control valve 33 and the high pressure side pressure P will be described. For example, when the outside air temperature is low, such as in winter, the difference from the low pressure side pressure is small because the high pressure side pressure P detected by the pressure detector 15 is low. Thereby, in the conventional cooling system, there exists a possibility that the oil return amount to the compressor 10 may fall rather than a setting amount. Therefore, in order to suppress a decrease in the amount of oil returned to the compressor 10, the controller 40 is adjusted so that the opening degree of the flow rate control valve 33 is increased so that the oil flow rate through the bypass passage 30 increases. Control. By controlling the flow rate of the oil passing through the bypass flow path 30, the set amount of oil returns to the compressor 10, so that a decrease in the amount of oil returned to the compressor 10 is suppressed. On the other hand, when the outside air temperature is high, for example, in summer, the difference from the low pressure side pressure is large because the high pressure side pressure P detected by the pressure detector 15 is high. As a result, in the conventional cooling system, the amount of oil returned to the compressor 10 increases and may exceed the set amount (see the broken line in FIG. 3). Therefore, in order to suppress an increase in the amount of oil returned to the compressor 10, the controller 40 adjusts the opening degree of the flow rate control valve 33 to be small so that the oil flow rate through the bypass passage 30 decreases. Control. By controlling the flow rate of the oil passing through the bypass flow path 30, the set amount of oil returns to the compressor 10, so that an increase in the amount of oil returned to the compressor 10 is suppressed (see the solid line in FIG. 3).

  Here, based on the oil temperature T detected by the oil temperature detector 16 and the high-pressure side pressure P detected by the pressure detector 15, the flow rate of the oil passing through the bypass passage 30 by adjusting the opening degree of the flow control valve 33. An example of controlling the above will be described.

  First, the control system configuration of the cooling system shown in FIG. 1 will be described.

  The controller 40 includes a microcomputer and various drivers. The controller 40 stores a set oil temperature T1, a set high-pressure side pressure P1, and the like serving as a reference when the opening degree of the flow control valve 33 is controlled. Further, based on the high-pressure side pressure P detected by the pressure detector 15 and the oil temperature T detected by the oil temperature detector 16, the flow rate of the oil passing through the bypass passage 30 is controlled by adjusting the opening degree of the flow control valve 33. To do.

  Next, the operation of the controller 40 will be described with reference to the flowchart of FIG.

  The high pressure side pressure P of the refrigerant / oil mixture immediately after being discharged from the compressor 10 is detected by the pressure detector 15 to determine whether or not the high pressure side pressure P is equal to or higher than the set high pressure side pressure P1 (step S1). .

  In step S1, when the high-pressure side pressure P is equal to or higher than the set high-pressure side pressure P1, the outside air temperature is high, so the viscosity of the oil passing through the oil separator 20 becomes low, and the amount of oil returned to the compressor 10 May rise. Therefore, the flow rate control valve 33 is adjusted so that the opening degree is decreased, and the flow rate of the oil passing through the bypass flow path 30 is controlled to decrease (step S2), and the oil return amount to the compressor 10 is set to a set amount. Adjust so that

  In step S1, when the high pressure side pressure P is not equal to or higher than the set high pressure side pressure P1, the oil temperature T after passing through the oil separator 20 is detected by the oil temperature detector 16, and the oil temperature T is set to the set oil temperature T1. It is determined whether or not this is the case (step S3).

  In step S3, when the oil temperature T is equal to or higher than the set oil temperature T1, the viscosity of the oil passing through the oil cooler 31 is lowered, and the amount of oil returned to the compressor 10 may be increased. Therefore, the flow rate control valve 33 is adjusted so that the opening degree is reduced, and the flow rate of oil passing through the bypass passage 30 is controlled to decrease (step S4), and the oil return amount to the compressor 10 is set to a set amount. Adjust so that

  In step S3, when the oil temperature T is not equal to or higher than the set oil temperature T1, the oil temperature T is low, so that the viscosity of the oil increases and the oil return amount to the compressor 10 may decrease. For this reason, it adjusts so that the opening degree of the flow control valve 33 may become large, it controls so that the flow volume of the oil which passes the bypass flow path 30 increases (step S5), and the oil return amount to the compressor 10 is set. Adjust to an amount. Moreover, after controlling so that the flow volume of the oil which passes along the bypass flow path 30 increases in step S5, it returns to step S1.

  The operation of the cooling system configured as described above will be described.

  The refrigerant in the cooling system circulates in the order of the compressor 10 → the oil separator 20 → the condenser 11 → the expansion valve 12 → the evaporator 13 → the compressor 10 (see the solid line arrow in FIG. 1). Further, the oil flowing out of the compressor 10 together with the refrigerant circulates in the order of the compressor 10 → the oil separator 20 → the oil cooler 31 → the electromagnetic valve 32 → the flow control valve 33 → the compressor 10 (see the broken line arrow in FIG. 1). That is, oil that flows out of the compressor 10 together with the refrigerant is first separated from the refrigerant in the oil separator 20. Next, the oil separated from the refrigerant is cooled by the oil cooler 31 when passing through the bypass passage 30. Then, the flow rate of oil passing through the bypass passage 30 is controlled by adjusting the opening degree of the flow control valve 33. Thereby, low-temperature oil flows into the suction side of the compressor 10 while adjusting the flow rate of the oil returned to the compressor 10. When the low temperature oil returns to the compressor 10, the refrigerant temperature in the compressor 10 is lowered, and the refrigerant having the lowered temperature is supplied to the condenser 11.

  As described above, according to the cooling system of the present embodiment, the refrigerant whose temperature has decreased in the compressor 10 can flow into the condenser 11, so that it is condensed even when the outside air temperature is high, such as midsummer. The refrigerant can be reliably condensed in the vessel 11, and a decrease in the cooling efficiency of the cooling system can be prevented.

  Moreover, since the cooling system of this embodiment employs the air-cooled condenser 11 and the oil cooler 31 and can cool the refrigerant and oil without using water or the like, the running cost can be reduced.

  Furthermore, the cooling system of the present embodiment has the oil temperature T detected by the oil temperature detector 16 and the high pressure side pressure P detected by the pressure detector 15 when returning the oil cooled by the oil cooler 31 to the compressor 10. Based on this, the opening degree of the flow rate control valve 33 can be adjusted to return to the suction side of the compressor 10 while controlling the flow rate of oil passing through the bypass flow path 30, so that the oil in the compressor 10 is always set at a set amount. Therefore, it is possible to reliably prevent the lubrication failure and failure of the compressor 10.

  Moreover, since the cooling system of this embodiment can reduce the refrigerant | coolant temperature discharged from the compressor 10, even if it does not use an expensive heat resistant material, cheap material with low heat resistance is used for the compressor 10 or a condenser. 11 and the like, and the material cost can be reduced.

  Furthermore, since the cooling system of the present embodiment can stop the return of oil to the compressor 10 when the operation of the compressor 10 is stopped by opening and closing the electromagnetic valve 32, liquid compression of oil in the compressor 10 is possible. Thus, poor lubrication and failure of the compressor 10 can be more reliably prevented.

  4 and 5 show a cooling system according to a second embodiment of the present invention. FIG. 4 is a schematic configuration diagram of the cooling system, and FIG. 5 is a flowchart showing control of the cooling system. The same components as those in the cooling system shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The cooling system shown in FIG. 4 is different from the cooling system shown in FIG. 1 in that it includes a refrigerant temperature detector 17 that detects a refrigerant temperature T ′ in a gas state immediately after being discharged from the compressor 10.

  The cooling system shown in FIG. 4 is different from the cooling system shown in FIG. 1 in that the opening degree of the flow control valve 33 is controlled based on the refrigerant temperature T ′ detected by the refrigerant temperature detector 17.

  Here, the relationship between the opening degree of the flow control valve 33 and the refrigerant temperature T ′ will be described. When the refrigerant temperature T ′ is higher than the set refrigerant temperature T2 (for example, 100 ° C.), the controller 41 is adjusted so that the opening degree of the flow control valve 33 is increased in order to lower the refrigerant temperature in the compressor 10. The oil flow rate through the bypass passage 30 is controlled to increase. As a result, a large amount of oil cooled in the oil cooler 31 returns into the compressor 10, so that the refrigerant temperature in the compressor 10 decreases. On the other hand, for example, when the refrigerant temperature T ′ is lower than the set refrigerant temperature T3 (for example, 95 ° C.), the controller 41 adjusts the opening degree of the flow rate control valve 33 to be small, and the oil flow rate through the bypass passage 30 Is controlled to decrease. Thereby, since the flow volume of the oil which returns in the compressor 10 is small, the fall of the refrigerant temperature in the compressor 10 is suppressed.

  Here, an example in which the oil return amount to the compressor 10 is controlled by adjusting the opening degree of the flow control valve 33 based on the refrigerant temperature T ′ detected by the refrigerant temperature detector 17 will be described.

  First, the control system configuration of the cooling system shown in FIG. 4 will be described.

  The controller 41 includes a microcomputer and various drivers. The controller 41 stores preset refrigerant temperatures T2, T3, and the like that serve as a reference when controlling the opening degree of the flow control valve 33. Further, based on the refrigerant temperature T ′ detected by the refrigerant temperature detector 17, the opening degree of the flow control valve 33 is adjusted to control the oil return amount to the compressor 10.

  Next, the operation of the controller 41 will be described with reference to the flowchart of FIG.

  The refrigerant temperature T 'immediately after being discharged from the compressor 10 is detected by the refrigerant temperature detector 17, and it is determined whether or not the refrigerant temperature T' is equal to or higher than the set refrigerant temperature T2 (step S1).

  In step S1, when the refrigerant temperature T ′ is equal to or higher than the set refrigerant temperature T2, in order to reduce the refrigerant temperature in the compressor 10, the opening degree of the flow control valve 33 is adjusted so as to increase, Control is performed so that the flow rate of oil passing through the flow path 30 decreases (step S2), and the flow rate of oil returning to the compressor 10 is increased.

  In step S1, if the refrigerant temperature T 'is not equal to or higher than the set refrigerant temperature T2, it is determined whether or not the refrigerant temperature T' is equal to or lower than the set refrigerant temperature T3 (step S3).

  In step S3, when the refrigerant temperature T ′ is equal to or lower than the set refrigerant temperature T3, the opening degree of the flow control valve 33 is adjusted to be small in order to suppress a decrease in the refrigerant temperature in the compressor 10. Then, control is performed so that the flow rate of oil passing through the bypass flow path 30 is decreased (step S4), and the flow rate of oil returning to the compressor 10 is decreased.

  In step S3, when the refrigerant temperature T 'is not equal to or lower than the set refrigerant temperature T3, the process returns to step S1.

  Since the operation of the cooling system configured as described above is the same as that of the first embodiment, description thereof is omitted.

  Thus, according to the cooling system of this embodiment, the opening degree of the flow rate control valve 33 is adjusted based on the refrigerant temperature T ′ detected by the refrigerant temperature detector 17, and the flow rate of oil passing through the bypass flow path 30 is adjusted. Since it can be controlled, the temperature of the refrigerant discharged from the compressor 10 can be kept constant, and a decrease in the cooling efficiency of the cooling system can be prevented. Other operations and effects are the same as those in the first embodiment.

  FIG. 6 shows a cooling system according to a third embodiment of the present invention, and FIG. 6 is a schematic configuration diagram of the cooling system. In addition, the same component as the cooling system shown in FIG.1 and FIG.2 is represented with the same code | symbol, and the description is abbreviate | omitted.

  The cooling system shown in FIG. 6 increases or decreases the amount of oil returned to the compressor 10 by using an electromagnetic valve 45 that employs a duty control method.

  The cooling system shown in FIG. 6 differs from the cooling system shown in FIG. 1 in that the pressure control valve 46 is installed in parallel with the electromagnetic valve 45.

  The electromagnetic valve 45 is installed between the oil cooler 31 and the compressor 10. The electromagnetic valve 45 is open when the compressor 10 is in operation, and is closed when the compressor 10 is stopped. That is, the solenoid valve 45 returns the cooled oil to the suction side of the compressor 10 when the compressor 10 is operating, and stops the oil from returning when the compressor 10 is stopped. Further, the electromagnetic valve 45 employs a duty control system that increases or decreases the amount of oil returned to the compressor 10 by opening and closing the electromagnetic valve 45.

  The pressure control valve 46 is a well-known relief valve installed between the oil cooler 31 and the compressor 10, and is arranged in parallel with the electromagnetic valve 32. The pressure control valve 46 has a structure that automatically opens when the pressure of the oil flowing through the bypass passage 30 becomes equal to or higher than a set pressure.

  The operation of the cooling system configured as described above will be described.

  The refrigerant in the cooling system circulates in the order of the compressor 10 → the oil separator 20 → the condenser 11 → the expansion valve 12 → the evaporator 13 → the compressor 10 (see the solid line arrow in FIG. 6). Moreover, the oil which flowed out with the refrigerant | coolant from the compressor 10 circulates in order of the compressor 10-> oil separator 20-> oil cooler 31-> electromagnetic valve 32-> compressor 10 (refer the broken line arrow of FIG. 6). That is, oil that flows out of the compressor 10 together with the refrigerant is first separated from the refrigerant in the oil separator 20. Next, the oil separated from the refrigerant is cooled by the oil cooler 31 when passing through the bypass passage 30. Then, the flow rate of oil passing through the bypass passage 30 is controlled by duty-controlling the electromagnetic valve 32. Thereby, low-temperature oil flows into the suction side of the compressor 10 while adjusting the flow rate of the oil returned to the compressor 10. When the low temperature oil returns to the compressor 10, the refrigerant temperature in the compressor 10 is lowered, and the refrigerant having the lowered temperature is supplied to the condenser 11. Further, when an abnormal pressure is generated in the bypass flow path 30 on the electromagnetic valve 32 side when the compressor 10 is operated or stopped, oil circulates in the bypass flow path 30 on the pressure control valve 46 side. When the pressure on the pressure control valve 46 side becomes equal to or higher than the set pressure, the pressure control valve 46 is automatically opened to release the pressure.

  Thus, according to the cooling system of the present embodiment, when an abnormal pressure is generated in the bypass flow path 30 on the electromagnetic valve 32 side, the pressure is released by automatically opening the pressure control valve 46. Failure of the electromagnetic valve 45 and damage to the bypass flow path 30 due to the liquid hammer can be prevented. Other operations and effects are the same as those in the first embodiment.

  FIG. 7 shows a cooling system according to a fourth embodiment of the present invention, and FIG. 7 is a schematic configuration diagram of the cooling system. In addition, the same component as the cooling system shown in FIG.1 and FIG.2 is represented with the same code | symbol, and the description is abbreviate | omitted.

  The cooling system shown in FIG. 7 is different from the cooling system shown in FIG. 1 in that two or more bypass flow paths 30 including electromagnetic valves 32 and flow control valves 33 are provided and the bypass flow paths 30 are branched. .

  The operation of the cooling system configured as described above will be described.

  The refrigerant in the cooling system circulates in the order of the compressor 10 → the oil separator 20 → the condenser 11 → the expansion valve 12 → the evaporator 13 → the compressor 10 (see the solid line arrow in FIG. 7). Further, the oil flowing out of the compressor 10 together with the refrigerant circulates in the order of the compressor 10 → the oil separator 20 → the oil cooler 31 → the electromagnetic valve 32 → the flow rate control valve 33 → the compressor 10 (see the broken line arrow in FIG. 7). That is, oil that flows out of the compressor 10 together with the refrigerant is first separated from the refrigerant in the oil separator 20. Next, the oil separated from the refrigerant is cooled by the oil cooler 31. Then, the flow rate of oil passing through each bypass passage 30 is controlled by adjusting the opening degree of each flow control valve 33 installed in each branched bypass passage 30. Thereby, low-temperature oil flows into the suction side of the compressor 10 while adjusting the flow rate of the oil returned to the compressor 10. When the low temperature oil returns to the compressor 10, the refrigerant temperature in the compressor 10 is lowered, and the refrigerant having the lowered temperature is supplied to the condenser 11.

  Thus, according to the cooling system of the present embodiment, the oil return amount to the compressor 10 is reduced by providing two or more bypass flow paths 30 including the electromagnetic valve 32 and the flow rate control valve 33. It can be adjusted with high accuracy. Other operations and effects are the same as those in the first embodiment.

  In addition, although the solenoid valve 32 of the cooling system of the said 1st Embodiment thru | or 4th Embodiment is arrange | positioned between the oil cooler 31 and the compressor 10, it is not restricted to this. For example, you may arrange | position between the oil separator 20 and the oil cooler 31. FIG.

  Furthermore, the cooling systems of the first embodiment, the third embodiment, and the fourth embodiment adjust the opening degree of the flow control valve 33 based on the oil temperature T and the high pressure side pressure P, and pass through the bypass flow path 30. Although the oil flow rate is controlled, the present invention is not limited to this. For example, the opening degree of the flow control valve 33 may be adjusted based only on the oil temperature T, and the flow rate of oil passing through the bypass flow path 30 may be controlled. In this case, the high pressure side pressure P is calculated from the oil temperature T, and the opening degree of the flow control valve 33 is adjusted from the oil temperature T and the calculated high pressure side pressure P.

  Furthermore, the cooling systems of the first embodiment, the third embodiment, and the fourth embodiment adjust the opening degree of the flow control valve 33 based on the oil temperature T and the high pressure side pressure P, and pass through the bypass flow path 30. Although the oil flow rate is controlled, the present invention is not limited to this. For example, the opening degree of the flow rate control valve 33 may be adjusted based on only the high pressure side pressure P, and the flow rate of oil passing through the bypass flow path 30 may be controlled. In this case, the oil temperature T is calculated from the high pressure side pressure P, and the opening degree of the flow control valve 33 is adjusted from the high pressure side pressure P and the calculated oil temperature T.

  Furthermore, the cooling systems of the first embodiment, the third embodiment, and the fourth embodiment adjust the opening degree of the flow control valve 33 based on the oil temperature T and the high pressure side pressure P, and pass through the bypass flow path 30. Although the oil flow rate is controlled, the present invention is not limited to this. For example, the opening degree of the flow rate control valve 33 is adjusted based on a detected value detected by a temperature sensor (not shown) as an outside air temperature detecting means to control the flow rate of oil passing through the bypass passage 30. May be. In this case, the high pressure side pressure P and the oil temperature T are calculated from the outside air temperature, and the opening degree of the flow control valve 33 is adjusted from the calculated high pressure side pressure P and the oil temperature T.

  The cooling systems of the first embodiment, the third embodiment, and the fourth embodiment adjust the opening degree of the flow control valve 33 based on the oil temperature T and the high pressure side pressure P, and pass through the bypass flow path 30. Although the oil flow rate is controlled, the present invention is not limited to this. For example, the opening degree of the flow control valve 33 is adjusted based on a detected value detected by a temperature sensor (not shown) as an outside air temperature detecting means and the oil temperature T, and the oil flowing through the bypass passage 30 is adjusted. The flow rate may be controlled. In this case, the high pressure side pressure P is calculated from the outside air temperature, and the opening degree of the flow control valve 33 is adjusted from the oil temperature T and the calculated high pressure side pressure P.

  Furthermore, the cooling systems of the first to fourth embodiments adjust the opening degree of the flow rate control valve 33 based on the high pressure side pressure P to control the flow rate of oil passing through the bypass flow path 30. However, it is not limited to this. For example, the low pressure side pressure is detected, the difference between the high pressure side pressure P and the low pressure side pressure is accurately calculated, the opening degree of the flow control valve 33 is adjusted based on this value, and the oil passing through the bypass passage 30 The flow rate may be controlled. Thereby, even in the case of a cooling system in which the fluctuation of the low-pressure side is severe, it is possible to reliably prevent a reduction in cooling efficiency of the cooling system and poor lubrication or failure of the compressor.

  Moreover, you may use together each detector 15,16,17 in the cooling system of the said 1st Embodiment and 2nd Embodiment. Furthermore, in the cooling system of the third embodiment and the fourth embodiment, the opening degree of the flow control valve 33 and the electromagnetic valve 45 is set based on the value detected from at least one of the detectors 15, 16, and 17. You may make it control.

1 is a schematic configuration diagram of a cooling system according to a first embodiment of the present invention. The flowchart which shows control of the cooling system which concerns on 1st Embodiment of this invention. The figure which shows the relationship between the high voltage | pressure side pressure and oil return amount of the cooling system which concerns on 1st Embodiment of this invention. The schematic block diagram of the cooling system which concerns on 2nd Embodiment of this invention. The flowchart which shows control of the cooling system which concerns on 2nd Embodiment of this invention. The schematic block diagram of the cooling system which concerns on 3rd Embodiment of this invention. The schematic block diagram of the cooling system which concerns on 4th Embodiment of this invention. Schematic configuration diagram of a conventional cooling system Schematic configuration diagram of a cooling system according to another conventional example Schematic configuration diagram of a cooling system according to another conventional example Schematic configuration diagram of a cooling system according to another conventional example Schematic configuration diagram of a cooling system according to another conventional example Schematic configuration diagram of a cooling system according to another conventional example

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Compressor, 11 ... Condenser, 12 ... Expansion valve, 13 ... Evaporator, 15 ... Pressure detector, 16 ... Oil temperature detector, 20 ... Oil separator, 30 ... Bypass flow path, 31 ... Oil cooler, 32 ... Solenoid valve, 33 ... Flow control valve, 40 ... Controller.

Claims (9)

In a cooling system comprising a refrigeration circuit comprising a compressor, a condenser, expansion means and an evaporator,
An oil separator that is provided between the compressor and the condenser and separates oil contained in the refrigerant discharged from the compressor from the refrigerant;
A bypass flow path for returning the oil separated by the oil separator to the suction side of the compressor;
An oil cooler for cooling the oil passing through the bypass flow path;
An oil return amount control means for controlling the flow rate of oil passing through the bypass flow path. The oil return amount control means is configured to increase the flow rate of the bypass flow path when the detected temperature detected by the oil temperature detection means is low, and to decrease the flow rate of the bypass flow path when the detected temperature is high. The cooling system according to claim 1, wherein: The oil return amount control means is configured to increase the flow rate of the bypass flow path when the detected temperature detected by the outside air temperature detection means is low, and to decrease the flow rate of the bypass flow path when the detected temperature is high. The cooling system according to claim 1 or 2, characterized by the above. The oil return amount control means is configured to increase the flow rate of the bypass flow path when the detected pressure detected by the oil pressure detection means is low and to decrease the flow rate of the bypass flow path when the detected pressure is high. The cooling system according to any one of claims 1 to 3, wherein the cooling system is characterized. Refrigerant temperature detection means for detecting the temperature of the refrigerant discharged from the compressor,
The oil return amount control means is configured to decrease the flow rate of the bypass flow path when the refrigerant temperature detected by the refrigerant temperature detection means is low, and to increase the flow rate of the bypass flow path when the refrigerant temperature is high. The cooling system according to any one of claims 1 to 4. The cooling system according to any one of claims 1 to 5, wherein a plurality of bypass passages whose flow rates are controlled by the oil return amount control means are provided. The cooling system according to any one of claims 1 to 6, wherein an electromagnetic valve that opens and closes the bypass flow path is provided in the bypass flow path. The cooling system according to any one of claims 1 to 7, wherein a pressure control valve that opens when a pressure of oil flowing through the bypass passage becomes a predetermined pressure or more is provided in the bypass passage. The cooling system according to any one of claims 1 to 8, wherein ammonia is used as the refrigerant.

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