JP2006023028A - Refrigerant cooling circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerant cooling circuit capable of optimally maintaining freezing efficiency based upon the pressure. <P>SOLUTION: A pressure of a high pressure side of a refrigerant circulation path is varied by controlling opening adjustment of a solenoid expansion valve 3, varying of a rotational frequency of a fan 21 in a gas cooler, varying of a rotational frequency of a fan 41 in an evaporator, varying of compression capacities of compressors 1 (1a and 1b), or opening and closing of solenoid valves 12a, 12b and 12c by a pressure control part 100 in response to a pressure detected by a pressure detecting means 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigerant cooling circuit that forms a refrigerant circulation path for cooling, for example, an interior of a heat insulating housing.

  2. Description of the Related Art Conventionally, for example, a refrigerant cooling circuit for cooling the inside of a refrigerator of a heat insulating housing such as a vending machine, a refrigerator, a freezer showcase / refrigerated showcase, or a beverage dispenser is known. The refrigerant cooling circuit forms a refrigerant circulation path for circulating the refrigerant mainly through the compressor, the radiator, the throttle unit, and the evaporator. As the refrigerant circulating in the refrigerant cooling circuit, a refrigerant having little influence on the global environment is used. For example, carbon dioxide is used as a refrigerant in that it has nonflammability, safety, and non-corrosion properties, and has little influence on the ozone layer.

  By the way, when carbon dioxide is used as the refrigerant in the refrigerant cooling circuit, the critical temperature of the carbon dioxide is as low as about 31 ° C., so that it is far more than when a conventional refrigerant (for example, HFC refrigerant (hydrofluorocarbon)) is used. Pressure increases. Further, the pressure changes because the optimum amount of refrigerant fluctuates according to the outside air temperature. For example, the pressure is low when the outside temperature is low, and the pressure is too high when the outside temperature is high. For this reason, at high and low temperatures, the pressure changes and the refrigeration efficiency decreases significantly. Therefore, conventionally, the refrigerant cooling circuit is controlled by detecting the temperature at a predetermined position in the refrigerant circulation path using a temperature sensor (see, for example, Patent Document 1).

JP 2004-54424 A

  However, the control according to the temperature change can suppress the pressure too high or too low, but an error occurs to maintain the desired pressure, and the refrigeration efficiency due to the pressure is reduced. Difficult to maintain optimal.

  An object of this invention is to provide the refrigerant cooling circuit which can maintain the refrigerating efficiency resulting from a pressure optimally in view of the said situation.

  In order to achieve the above object, a refrigerant cooling circuit according to claim 1 of the present invention includes a compressor that compresses a refrigerant, a radiator that dissipates heat supplied from the compressor, and is supplied from the radiator. In the refrigerant cooling circuit having a refrigerant circulation path having a throttle part for adjusting the flow rate of the refrigerant and an evaporator for evaporating the refrigerant supplied from the throttle part and returning it to the compressor, the refrigerant circulation path The pressure detecting means for detecting the pressure of the refrigerant is provided on the high pressure side of the gas, and the flow rate of the refrigerant is varied by the throttle in accordance with the pressure detected by the pressure detecting means.

  A refrigerant cooling circuit according to a second aspect of the present invention includes a compressor that compresses the refrigerant, a radiator that dissipates the refrigerant supplied from the compressor, and a throttle that adjusts the flow rate of the refrigerant supplied from the radiator. And a refrigerant cooling circuit having a refrigerant circulation path having an evaporator for evaporating the refrigerant supplied from the throttle and returning the refrigerant to the compressor, the pressure of the refrigerant is detected on the high pressure side of the refrigerant circulation path The pressure detection means is provided, and the air volume of the blower that blows air to the radiator or the blower that blows to the evaporator is varied according to the pressure detected by the pressure detection means.

  A refrigerant cooling circuit according to a third aspect of the present invention includes a compressor that compresses the refrigerant, a radiator that dissipates the refrigerant supplied from the compressor, and a throttle that adjusts the flow rate of the refrigerant supplied from the radiator. And a refrigerant cooling circuit having a refrigerant circulation path having an evaporator for evaporating the refrigerant supplied from the throttle and returning the refrigerant to the compressor, the pressure of the refrigerant is detected on the high pressure side of the refrigerant circulation path The pressure detection means is provided, and the compression capacity of the refrigerant in the compressor is varied according to the pressure detected by the pressure detection means.

  A refrigerant cooling circuit according to a fourth aspect of the present invention includes a compressor that compresses the refrigerant, a radiator that dissipates the refrigerant supplied from the compressor, and a throttle that adjusts the flow rate of the refrigerant supplied from the radiator. And a refrigerant cooling circuit having a refrigerant circulation path having an evaporator for evaporating the refrigerant supplied from the throttle and returning the refrigerant to the compressor, the pressure of the refrigerant is detected on the high pressure side of the refrigerant circulation path The pressure detecting means is provided, and according to the pressure detected by the pressure detecting means, the flow rate of the refrigerant is variable at the throttle portion, the air volume of the blower that blows air to the radiator or the air blower that blows to the evaporator, or It is characterized by selectively combining variable refrigerant compression capacities in the compressor.

  A refrigerant cooling circuit according to a fifth aspect of the present invention includes a compressor that compresses the refrigerant, a radiator that dissipates the refrigerant supplied from the compressor, and a throttle that adjusts the flow rate of the refrigerant supplied from the radiator. And an evaporator for evaporating the refrigerant supplied from the throttle unit and returning it to the compressor, and a plurality of the evaporators are provided to share the compressor, the radiator and the throttle unit. In the refrigerant cooling circuit in which an electromagnetic valve for opening and closing each refrigerant circulation path is provided in a path between the throttle unit and each evaporator, the refrigerant circulation path is provided on the high pressure side of the refrigerant circulation path. Pressure detecting means for detecting the pressure of the refrigerant is provided, and the electromagnetic valves are opened and closed according to the pressure detected by the pressure detecting means.

  A refrigerant cooling circuit according to a sixth aspect of the present invention includes a compressor that compresses the refrigerant, a radiator that dissipates the refrigerant supplied from the compressor, and a throttle that adjusts the flow rate of the refrigerant supplied from the radiator. And an evaporator for evaporating the refrigerant supplied from the throttle unit and returning it to the compressor, and a plurality of the evaporators are provided to share the compressor, the radiator and the throttle unit. In the refrigerant cooling circuit in which an electromagnetic valve for opening and closing each refrigerant circulation path is provided in a path between the throttle unit and each evaporator, the refrigerant circulation path is provided on the high pressure side of the refrigerant circulation path. Pressure detecting means for detecting the pressure of the refrigerant is provided, and the flow rate of the refrigerant is variable at the throttle portion according to the pressure detected by the pressure detecting means, the blower that blows air to the radiator or the blower that blows air to the evaporator Air volume is acceptable , And performs the variable compression capability of the refrigerant in the compressor, or selectively combined opening and closing of the respective solenoid valves.

  A refrigerant cooling circuit according to a seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects, the refrigerant is carbon dioxide.

  The refrigerant cooling circuit according to the present invention varies the flow rate of the refrigerant in the throttle portion according to the pressure detected by the pressure detecting means. For example, when the detected pressure is lower than the desired pressure, the pressure is increased by reducing the flow rate of the refrigerant at the throttle. On the other hand, when the detected pressure is higher than the desired pressure, the flow rate of the refrigerant at the throttle is increased to lower the pressure. As a result, the refrigeration efficiency resulting from the pressure can be optimally maintained.

  The refrigerant cooling circuit according to the present invention varies the air volume of the blower that blows air to the radiator or the blower that blows to the evaporator according to the pressure detected by the pressure detection means. For example, when the detected pressure is lower than the desired pressure, the air volume of the blower that blows air to the radiator or the blower that blows air to the evaporator is reduced to increase the pressure. On the other hand, when the detected pressure is higher than the desired pressure, the air volume of the blower that blows air to the radiator or the blower that blows to the evaporator is increased to lower the pressure. As a result, the refrigeration efficiency resulting from the pressure can be optimally maintained.

  The refrigerant cooling circuit according to the present invention varies the compression capacity of the refrigerant in the compressor according to the pressure detected by the pressure detection means. For example, when the detected pressure is lower than the desired pressure, the compression capacity of the compressor is increased to increase the pressure. On the other hand, when the detected pressure is higher than the desired pressure, the compression capacity of the compressor is lowered to lower the pressure. As a result, the refrigeration efficiency resulting from the pressure can be optimally maintained.

  The refrigerant cooling circuit according to the present invention is a refrigerant cooling circuit in which an electromagnetic valve that opens and closes each refrigerant circulation path is provided in a path between the throttle unit and the plurality of evaporators. Open and close each solenoid valve accordingly. For example, when the detected pressure is lower than the desired pressure, the number of open solenoid valves is decreased to increase the pressure. On the other hand, when the detected pressure is higher than the desired pressure, the number of open solenoid valves is increased to lower the pressure. As a result, the refrigeration efficiency resulting from the pressure can be optimally maintained.

  In addition, the refrigerant cooling circuit according to the present invention can change the flow rate of the refrigerant at the throttle, the air volume of the blower that blows to the radiator or the air blower that blows to the evaporator, and the compression according to the pressure detected by the pressure detecting means. This is done by changing the compression capacity of the refrigerant in the machine or selectively opening and closing each solenoid valve. As a result, the refrigeration efficiency resulting from the pressure can be more optimally maintained.

  In particular, the evaporation means of the present invention is useful for a refrigerant cooling circuit in which the refrigerant circulation path is in a relatively high pressure state using carbon dioxide as the refrigerant.

  Exemplary embodiments of a refrigerant cooling circuit according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a schematic view showing an embodiment of a refrigerant cooling circuit according to the present invention. As shown in FIG. 1, the refrigerant cooling circuit in this embodiment mainly includes a compressor 1, a gas cooler (heat radiator) 2, an electronic expansion valve (throttle portion) 3, and an evaporator 4 to connect refrigerant. A circulating refrigerant circulation path is formed. In the present embodiment, for example, carbon dioxide is used as the refrigerant. Carbon dioxide is a refrigerant that has non-flammability, safety, and non-corrosion properties, and has little influence on the ozone layer.

  The compressor 1 compresses the carbon dioxide returned from the evaporator 4 to bring it into a high temperature and high pressure state. In the present embodiment, the compressor 1 uses the intermediate heat exchanger 10 to perform a two-stage compression operation. Specifically, in the two-stage compression operation, the compressor 1 has an intermediate heat between the first compressor 1a that performs the first-stage compression operation and the second compressor 1b that performs the second-stage compression operation. An exchanger 10 is provided. Then, after the first stage compression operation by the first compressor 1a, the intermediate heat exchanger 10 cools the carbon dioxide compressed by the first compressor 1a and returns it to the second compressor 1b. In this way, the compressor 1 performs a two-stage compression operation via the intermediate heat exchanger 10, thereby obtaining high compression efficiency with low power consumption and compressing carbon dioxide to a desired high temperature and high pressure state. It becomes possible to do. In this embodiment, carbon dioxide is compressed to about 6 MPa by the first stage compression by the first compressor 1a, and carbon dioxide is about 9 MPa (7 MPa or more by the second stage compression by the second compressor 1b. ).

  An oil separator 11 is connected to the compressor 1. The oil separator 11 is for returning the refrigeration oil discharged from the compressor 1 from the high pressure side to the low pressure side of the refrigerant circulation path. The high pressure side of the refrigerant circulation path is from the outlet side of the compressor 1 to the inlet side of the electronic expansion valve 3 through the gas cooler 2. The low pressure side of the refrigerant circulation path is from the outlet side of the electronic expansion valve 3 to the inlet side of the compressor 1 through the evaporator 4. The refrigerating machine oil prevents friction and refrigerant leakage in the compressor 1, but it is difficult to completely seal the refrigerating machine oil inside the compressor 1. In particular, the compressor 1 compresses carbon dioxide to a high pressure as described above, and this pressure is much higher than when a conventional refrigerant (for example, HFC refrigerant (hydrofluorocarbon)) is used. The amount of refrigeration oil discharged from the machine 1 increases. Therefore, in the present embodiment, in the compressor 1, the oil separator 11 is connected between the outlet side of the second compressor 1b and the inlet side of the first compressor 1a, and discharged from the second compressor 1b. The refrigerating machine oil thus returned is returned to the first compressor 1a. In this embodiment, since the pressure of carbon dioxide is high, a refrigerating machine oil having a viscosity index of approximately 100 (40 ° C., 0 Wt%) is employed for the purpose of preventing friction and refrigerant leakage inside the compressor 1 as much as possible. It is.

  The compressor 1 includes a reciprocating compressor, a rotary compressor, a scroll compressor, or an inverter compressor that can adjust the compression capacity thereof. And what is necessary is just to apply suitably the compressor corresponding to the object which arrange | positions a refrigerant | coolant cooling circuit, an environment, or the cost of a refrigerant | coolant cooling circuit.

  The gas cooler 2 is for liquefying carbon dioxide by releasing heat from high-temperature and high-pressure carbon dioxide supplied from the compressor 1. The gas cooler 2 in the present embodiment uses a fin tube type composed of, for example, a copper tube and an aluminum fin. The gas cooler 2 is provided with a fan (blower) 21. The fan 21 is for blowing the gas cooler 2 and is driven by a fan motor 22.

  The electronic expansion valve 3 is for reducing the pressure of carbon dioxide supplied from the gas cooler 2 and controlling the evaporation temperature and flow rate. The electronic expansion valve 3 has a valve for adjusting the pressure of carbon dioxide. The electronic expansion valve 3 increases the resistance through which carbon dioxide passes by increasing the opening of the valve to increase the pressure, while reducing the resistance through which carbon dioxide passes by increasing the opening of the valve. Lower the pressure. As a configuration for adjusting the opening degree of the valve, in this embodiment, it is based on a motor drive capable of stepless adjustment.

  The evaporator 4 is for cooling the ambient temperature by absorbing ambient heat when the liquid carbon dioxide supplied from the electronic expansion valve 3 evaporates. The evaporator 4 in the present embodiment uses a fin tube type composed of, for example, a copper tube and an aluminum fin. The evaporator 4 is provided with a fan (blower) 41. The fan 41 is for blowing the evaporator 4 and is driven by a fan motor 42.

  The evaporator 4 is arrange | positioned inside the refrigerator of the heat insulation housing | casing in a vending machine, a refrigerator, a freezer showcase, a refrigerated showcase, or a drink dispenser etc., for example. In particular, in this embodiment, for example, in an automatic vending machine, in order to cool a plurality of (three rooms in the embodiment) refrigerators (product storage units) independently, the evaporators 4 (4a, 4a, 4b, 4c) are arranged respectively. That is, the evaporators 4a, 4b, and 4c are connected to respective paths branched from the electronic expansion valve 3 in three directions. Further, electromagnetic valves 12a, 12b, and 12c are provided on the inlet sides of the evaporators 4a, 4b, and 4c in the respective paths. And carbon dioxide from the electronic expansion valve 3 is supplied to each evaporator 4a, 4b, 4c by selectively open | releasing each solenoid valve 12a, 12b, 12c. Further, the outlet-side paths of the evaporators 4a, 4b, and 4c are gathered together and connected to the first compressor 1a of the compressor 1. The solenoid valves 12a, 12b, and 12c in the present embodiment are configured so that the valve body is seated by utilizing a pressure difference between the inlet side and the outlet side (for example, the inlet side is high pressure and the output side is low pressure) and spring elastic force. A configuration is adopted in which the valve body is separated from the valve seat and opened when the electromagnetic coil portion is energized from this state.

  The decompression means 13a is connected to each of the evaporators 4a, 4b, and 4c from the electronic expansion valve 3 and between each of the solenoid valves 12a, 12b, and 12c and each of the evaporators 4a, 4b, and 4c. , 13b, 13c are provided. The decompression means 13a, 13b, and 13c act as throttles that provide pressure resistance in the path between the electromagnetic valves 12a, 12b, and 12c and the evaporators 4a, 4b, and 4c. The decompression means 13a, 13b, and 13c in the present embodiment are formed as orifices provided in the respective paths. The decompression means 13a, 13b, and 13c are not limited to orifices as long as they function as a throttle that provides pressure resistance in the path.

  Note that the temperature at the periphery of the evaporator 4 decreases as the evaporator 4 absorbs the heat at the periphery. As the refrigeration cycle, it is necessary to throw away the heat of evaporation absorbed by the evaporator 4, but the inside of the heat-insulating housing provided with the evaporator 4 is considerably lower than the outside temperature, and is taken away from the low temperature part. Heat cannot be thrown away directly to the hot outside. Therefore, the compressor 1 plays the role of converting carbon dioxide supplied from the evaporator 4 into high-temperature and high-pressure steam in order to discard the evaporation heat of the evaporator 4 at a temperature higher than the outside air temperature.

  Further, when carbon dioxide is used as a refrigerant, the temperature of the gas cooler 2 may exceed the critical temperature of carbon dioxide (about 31 ° C.) in summer when the outside air temperature becomes high. In this case, the gas cooler 2 is in a supercritical pressure state in which carbon dioxide is not vaporized while being vaporized. On the other hand, it is desirable that all the carbon dioxide that has passed through the evaporator 4 is vaporized. If the carbon dioxide that has passed through the evaporator 4 is supplied to the compressor 1 while being partially liquefied, the compressor 1 may cause liquid compression and damage the cylinder.

  Therefore, an internal heat exchanger 14 is provided between the gas cooler 2 and the electronic expansion valve 3 and between the evaporator 4 and the compressor 1 (first compressor 1a). Although not clearly shown in the figure, inside the internal heat exchanger 14, a refrigerant line between the gas cooler 2 and the electronic expansion valve 3 and a refrigerant line between the evaporator 4 and the compressor 1 are They are arranged so as to have non-contact countercurrent with a distance allowing heat exchange with each other. Thereby, the carbon dioxide obtained from the gas cooler 2 becomes easy to liquefy. On the other hand, the carbon dioxide vaporized from the evaporator 4 is supplied to the compressor 1.

  Further, with respect to the evaporator 4 provided inside the cooler of the heat insulating housing, dew condensation water or the like is generated as drainage during the refrigerant circulation operation to the refrigerant circulation path. Then, the waste water is led to the evaporation means 15 located outside the cooler and provided with the compressor 1, the gas cooler 2, and the like. The evaporation means 15 is provided between the compressor 1 (second compressor 1 b) and the gas cooler 2 and in a path between the outlet side of the oil separator 11 and the inlet side of the gas cooler 2. Although not clearly shown in the figure, the evaporating means 15 includes an evaporating dish into which drainage is guided, an evaporating pipe disposed inside the evaporating dish, and a water-absorbing evaporating sheet related to the evaporating pipe. The evaporation pipe is connected to a path between the outlet side of the oil separator 11 and the inlet side of the gas cooler 2, and high-temperature and high-pressure carbon dioxide discharged from the compressor 1 passes therethrough. That is, the waste water led to the evaporating dish is heated by the evaporating pipe through which high-temperature and high-pressure carbon dioxide passes, and is absorbed by the evaporating sheet and evaporates. At this time, carbon dioxide passing through the evaporation pipe is pre-cooled by drainage.

  Further, pressure detection means 16 is provided on the high pressure side of the refrigerant circulation path. The pressure detection means 16 detects the pressure on the high pressure side of the refrigerant circulation path. The pressure detection means 16 in the present embodiment is provided at the site of the oil separator 11. The pressure detection means 16 includes, for example, a Purdon tube type, a bellows type, or a semiconductor type.

  Hereinafter, the operation of the refrigerant cooling circuit of the present invention using carbon dioxide as the refrigerant will be described. In the following operation of the refrigerant cooling circuit, only the electromagnetic valve 12a is open, and the other electromagnetic valves 12b and 12c are closed.

  The carbon dioxide returned from the evaporator 4a in the refrigerator is sucked into the first compressor 1a via the internal heat exchanger 14 and compressed at a low pressure (compressed to about 6 MPa). The carbon dioxide discharged from the first compressor 1a is cooled through the intermediate heat exchanger 10, and then sucked into the second compressor 1b and compressed at a high pressure (compressed to about 9 MPa). At this time, the refrigerating machine oil discharged together with carbon dioxide from the second compressor 1b is returned to the inlet side of the first compressor 1a by the oil separator 11.

  Next, the carbon dioxide discharged from the second compressor 1 b is pre-cooled by the evaporation means 15 and sent to the gas cooler 2. The carbon dioxide sent to the gas cooler 2 is radiated and liquefied, and reaches the electronic expansion valve 3 via the internal heat exchanger 14.

  Next, in the electronic expansion valve 3, the carbon dioxide is depressurized and the evaporation temperature and flow rate are controlled. Thereafter, the carbon dioxide passes through the electromagnetic valve 12a in the open state and reaches the evaporator 4a through the decompression means 13a.

  Finally, the carbon dioxide supplied to the evaporator 4a absorbs heat and is vaporized as heated steam. The inside of the refrigerator provided with the evaporator 4a is cooled independently by the absorption of carbon dioxide. The carbon dioxide is sucked from the evaporator 4a through the internal heat exchanger 14 to the first compressor 1a and returned to be circulated.

  Note that, in the carbon dioxide circulation operation, the evaporators 4b and 4c provided in the path having the solenoid valves 12b and 12c in the closed state are the same as the evaporator 4a in the refrigerant circulation path in which the circulation operation is performed. The exit side is gathered. For this reason, conventionally, when only the solenoid valve 12a is in an open state, the pressure difference between the inlet side and the outlet side of the solenoid valves 12b and 12c in the closed state becomes substantially equal. However, in this embodiment, decompression means 13a, 13b, and 13c are provided in the paths between the electromagnetic valves 12a, 12b, and 12c and the evaporators 4a, 4b, and 4c, respectively. For this reason, in the path having the closed solenoid valves 12b and 12c, the decompression means 13b and 13c act as a throttle for applying pressure resistance in the path, so that the outlet side of the closed solenoid valves 12b and 12c has a low pressure. The inlet side becomes high pressure. Accordingly, a pressure difference is generated between the inlet side and the outlet side of the electromagnetic valves 12b and 12c in the closed state, and the closed state of the electromagnetic valves 12b and 12c is assisted by the pressure difference between the inlet side and the outlet side. The closed state of the electromagnetic valves 12b and 12c is maintained.

  FIG. 2 shows a pressure control system in the refrigerant cooling circuit shown in FIG. As shown in FIG. 2, the refrigerant cooling circuit includes a pressure control unit 100. The pressure control unit 100 receives a detection signal from the pressure detection means 16 during operation of the refrigerant cooling circuit, and causes the high pressure side to have a desired pressure (for example, approximately 7 MPa) according to a program and data stored in the memory 101 in advance. The electronic expansion valve 3, the fans 21, 41, the compressor 1 (1a, 1b) and the electromagnetic valves 12a, 12b, 12c are controlled.

  In the carbon dioxide circulation operation, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is lower than the desired pressure, the pressure control unit 100 reduces the opening of the electronic expansion valve 3. And reduce the flow rate of carbon dioxide. This increases the pressure on the high pressure side. On the other hand, when the high pressure side pressure is received from the pressure detection means 16 and the pressure is higher than the desired pressure, the pressure control unit 100 increases the opening of the electronic expansion valve 3 to increase the flow rate of carbon dioxide. Increase. This lowers the pressure on the high pressure side. Note that the opening degree data of the electronic expansion valve 3 that varies according to the detected pressure on the high pressure side is stored in the memory 101 in advance.

  In the carbon dioxide circulation operation, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is lower than the desired pressure, the pressure control unit 100 sets the fan motor of the fan 21 in the gas cooler 2. Decrease the speed of 22 to reduce the air volume. Thereby, the temperature of the gas cooler 2 rises and the pressure on the high pressure side increases. On the other hand, when the high pressure side pressure is received from the pressure detection means 16 and the pressure is higher than the desired pressure, the pressure control unit 100 increases the rotational speed of the fan motor 22 of the fan 21 in the gas cooler 2 to increase the air volume. Increase. As a result, the temperature of the gas cooler 2 is lowered and the pressure on the high pressure side is lowered. Note that the rotational speed data of the fan motor 22 that varies according to the detected pressure on the high pressure side is stored in the memory 101 in advance.

  In the carbon dioxide circulation operation, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is lower than the desired pressure, the pressure control unit 100 performs the fan motor of the fan 41 in the evaporator 4. Increasing the number of revolutions 42 increases the air volume. As a result, the temperature of the evaporator 4 is lowered and the pressure on the high pressure side is increased. On the other hand, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is higher than the desired pressure, the pressure control unit 100 reduces the rotational speed of the fan motor 42 of the fan 41 in the evaporator 4 to reduce the air volume. Reduce. As a result, the temperature of the evaporator 4 increases and the pressure on the high pressure side decreases. Note that the data of the rotational speed of the fan motor 42 that varies according to the detected pressure on the high pressure side is stored in the memory 101 in advance.

  In the carbon dioxide circulation operation, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is lower than the desired pressure, the pressure control unit 100 in the compressor 1 (1a, 1b) Increase the inverter frequency. Thereby, the compression capacity of the compressor 1 (1a, 1b) is increased, and the pressure on the high pressure side is increased. On the other hand, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is higher than the desired pressure, the pressure control unit 100 reduces the frequency of the inverter in the compressor 1 (1a, 1b). As a result, the compression capacity of the compressor 1 (1a, 1b) is lowered and the pressure on the high pressure side is lowered. Note that inverter frequency data that varies according to the detected pressure on the high-pressure side is stored in the memory 101 in advance.

  In the carbon dioxide circulation operation, when the high pressure side pressure is received from the pressure detecting means 16 and the pressure is lower than the desired pressure, the pressure control unit 100 opens the electromagnetic valves 12a, 12b, and 12c. Reduce the number in the state. This reduces the resistance through which carbon dioxide passes and increases the pressure on the high pressure side. On the other hand, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is higher than the desired pressure, the pressure control unit 100 increases the number of the electromagnetic valves 12a, 12b, and 12c in the open state. This increases the resistance through which carbon dioxide passes and reduces the pressure on the high pressure side. Note that data of the solenoid valves 12a, 12b, and 12c that open and close according to the detected pressure on the high pressure side is stored in the memory 101 in advance.

  In the carbon dioxide circulation operation, when the pressure on the high pressure side is received from the pressure detection means 16 and the pressure is lower than the desired pressure, the pressure control unit 100 is connected to the electronic expansion valve 3 and the gas cooler 2. It is also possible to selectively combine the above-described controls for increasing the pressure of the fan 21, the fan 41 in the evaporator 4, the compressor 1 (1a, 1b) or the electromagnetic valves 12a, 12b, 12c. On the other hand, when the pressure on the high-pressure side is received from the pressure detection means 16 and the pressure is higher than the desired pressure, the pressure control unit 100 includes the electronic expansion valve 3, the fan 21 in the gas cooler 2, and the fan in the evaporator 4. 41. It is also possible to selectively combine the above-described controls for reducing the pressure of the compressor 1 (1a, 1b) or the solenoid valves 12a, 12b, 12c.

  As described above, in the refrigerant cooling circuit described above, the opening degree of the electronic expansion valve 3 is adjusted according to the pressure detected by the pressure detection means 16, the rotation speed of the fan 21 in the gas cooler is variable, and the fan 41 in the evaporator is adjusted. The pressure on the high pressure side of the refrigerant circulation path is varied by varying the number of revolutions, varying the compression capacity of the compressor 1 (1a, 1b), or controlling the opening and closing of the electromagnetic valves 12a, 12b, 12c by the pressure control unit 100. For this reason, it is possible to optimally maintain the refrigeration efficiency due to the pressure in the refrigerant cooling circuit. For example, as shown in the TS diagram of FIG. 3, when the pressure on the high pressure side of the refrigerant circulation path is equal to or lower than the critical pressure, this pressure is detected by the pressure detecting means 16 and the pressure control unit 100 detects the pressure. The pressure on the high-pressure side is changed to a critical pressure or higher. As a result, the refrigeration efficiency Q2 when the pressure on the high pressure side is equal to or higher than the critical pressure is higher than the refrigeration efficiency Q2 when the pressure on the high pressure side is lower than the critical pressure, and the refrigeration efficiency is improved.

  The operating condition of the refrigerant cooling circuit varies greatly depending on the ambient temperature. In order to absorb this fluctuation and to operate optimally, the conventional refrigerant cooling circuit is controlled by a temperature sensor or a current value. However, since the temperature sensor has a heat capacity, it does not immediately follow the fluctuation state. In addition, the current value varies and varies. For this reason, it may not be optimally controlled in a driving situation where fluctuations are severe. On the other hand, the pressure detecting means 16 in the present invention can directly and immediately express the fluctuation of the refrigerant cooling circuit. For this reason, when the pressure increases and an overload occurs, the opening degree of the electronic expansion valve 3 is increased, a large amount of refrigerant is flowed, and the refrigerant is moved from the high pressure side to the constant pressure side, thereby releasing the overload situation. In addition, the refrigerant is moved from the high pressure side to the low pressure side by lowering the frequency of the inverter in the compressor 1 (1a, 1b) or lowering the rotational speed of the fan 41 in the evaporator 4 (4a, 4b, 4c). Overload status can be canceled. Further, when the ambient temperature becomes low, the pressure on the high pressure side becomes low and the flow of the refrigerant decreases. In this case, the pressure on the high pressure side is increased by decreasing the opening degree of the electronic expansion valve 3, increasing the frequency of the inverter in the compressor 1 (1a, 1b), or decreasing the rotational speed of the fan 21 in the gas cooler 2. Thus, the circulation amount of the refrigerant can be increased. Thus, by controlling according to the detection of the pressure detection means 16, it becomes possible to operate the refrigerant cooling circuit in an appropriate pressure state.

It is the schematic which shows one Example of the refrigerant cooling circuit which concerns on this invention. It is a block diagram which shows the control system of the pressure in the refrigerant | coolant cooling circuit shown in FIG. It is a TS diagram which shows the characteristic of the refrigerant cooling circuit shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 1a 1st compressor 1b 2nd compressor 2 Gas cooler (heat radiator)
21 Fan (blower)
22 Fan motor 3 Electronic expansion valve (throttle part)
4 (4a, 4b, 4c) Evaporator 41 Fan (blower)
42 Fan motor 10 Intermediate heat exchanger 11 Oil separator 12a, 12b, 12c Solenoid valve 13a, 13b, 13c Pressure reducing means 14 Internal heat exchanger 15 Evaporating means 16 Pressure detecting means 100 Pressure control part 101 Memory

Claims (7)

A compressor that compresses the refrigerant; a radiator that dissipates the refrigerant supplied from the compressor; a throttle that adjusts a flow rate of the refrigerant supplied from the radiator; and a refrigerant supplied from the throttle In a refrigerant cooling circuit that forms a refrigerant circulation path with an evaporator to be returned to the compressor,
A refrigerant cooling circuit comprising pressure detecting means for detecting the pressure of the refrigerant on the high pressure side of the refrigerant circulation path, and varying the flow rate of the refrigerant in the throttle portion according to the pressure detected by the pressure detecting means. . A compressor that compresses the refrigerant; a radiator that dissipates the refrigerant supplied from the compressor; a throttle that adjusts a flow rate of the refrigerant supplied from the radiator; and a refrigerant supplied from the throttle In a refrigerant cooling circuit that forms a refrigerant circulation path with an evaporator to be returned to the compressor,
Pressure detection means for detecting the pressure of the refrigerant is provided on the high pressure side of the refrigerant circulation path, and the air volume of the blower that blows air to the radiator or the evaporator is variable according to the pressure detected by the pressure detection means. A refrigerant cooling circuit. A compressor that compresses the refrigerant; a radiator that dissipates the refrigerant supplied from the compressor; a throttle that adjusts a flow rate of the refrigerant supplied from the radiator; and a refrigerant supplied from the throttle In a refrigerant cooling circuit that forms a refrigerant circulation path with an evaporator to be returned to the compressor,
Refrigerant cooling characterized in that pressure detection means for detecting the pressure of the refrigerant is provided on the high pressure side of the refrigerant circulation path, and the compression capacity of the refrigerant in the compressor is varied according to the pressure detected by the pressure detection means. circuit. A compressor that compresses the refrigerant; a radiator that dissipates the refrigerant supplied from the compressor; a throttle that adjusts a flow rate of the refrigerant supplied from the radiator; and a refrigerant supplied from the throttle In a refrigerant cooling circuit that forms a refrigerant circulation path with an evaporator to be returned to the compressor,
Pressure detecting means for detecting the pressure of the refrigerant is provided on the high pressure side of the refrigerant circulation path, and the flow rate of the refrigerant is variable at the throttle portion according to the pressure detected by the pressure detecting means, A refrigerant cooling circuit characterized by selectively combining variable air volume of an air blower that blows to the evaporator or variable refrigerant compression capacity in the compressor. A compressor that compresses the refrigerant; a radiator that dissipates the refrigerant supplied from the compressor; a throttle that adjusts a flow rate of the refrigerant supplied from the radiator; and a refrigerant supplied from the throttle An evaporator for returning to the compressor, and a plurality of the evaporators are provided to form a plurality of refrigerant circulation paths that share the compressor, the radiator and the throttle, and the throttle In the refrigerant cooling circuit provided with a solenoid valve for opening and closing each refrigerant circulation path in a path between each evaporator,
A refrigerant cooling circuit comprising pressure detecting means for detecting the pressure of the refrigerant on the high pressure side of the refrigerant circulation path, and opening and closing each electromagnetic valve according to the pressure detected by the pressure detecting means. A compressor that compresses the refrigerant; a radiator that dissipates the refrigerant supplied from the compressor; a throttle that adjusts a flow rate of the refrigerant supplied from the radiator; and a refrigerant supplied from the throttle An evaporator for returning to the compressor, and a plurality of the evaporators are provided to form a plurality of refrigerant circulation paths that share the compressor, the radiator and the throttle, and the throttle In the refrigerant cooling circuit provided with a solenoid valve for opening and closing each refrigerant circulation path in a path between each evaporator,
Pressure detecting means for detecting the pressure of the refrigerant is provided on the high pressure side of the refrigerant circulation path, and the flow rate of the refrigerant is variable at the throttle portion according to the pressure detected by the pressure detecting means, the blower for blowing air to the radiator, or A refrigerant cooling circuit, wherein the air volume of a blower blown to the evaporator is varied, the refrigerant compression capacity of the compressor is varied, or the electromagnetic valves are selectively opened and closed.   The refrigerant cooling circuit according to any one of claims 1 to 6, wherein the refrigerant is carbon dioxide.

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