JP5239204B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus and a control method thereof.

  Generally, if the refrigerant in the refrigeration cycle leaks due to poor installation work such as a hot water supply device having a refrigeration cycle device, damage to the piping, etc., the pressure of the entire refrigeration cycle decreases, or the refrigerant circulation amount is insufficient. As a result, the capacity is reduced, and further, if the operation is continued with a shortage of refrigerant, the compressor may be damaged.

  Therefore, for the purpose of preventing the failure due to the refrigerant leakage as described above, a determination means for determining the refrigerant shortage is provided. For example, when the discharge temperature of the compressor exceeds a set value and the energization current of the compressor is lower than the set value, the judging means for judging the refrigerant shortage or the circulation amount of the fluid that exchanges heat with the refrigerant by the radiator And the fluid radiator outlet temperature, and the temperature difference between the target value of the fluid radiator outlet temperature and the detected value of the fluid radiator outlet temperature is calculated. Yes, and the temperature difference between the target value and the detected value of the fluid radiator outlet temperature is greater than or equal to a predetermined value as a criterion for lack of refrigerant (see, for example, Patent Documents 1 and 2) .

  On the other hand, hydrocarbons (fluorocarbons) containing fluorine atoms have been used as the refrigerant sealed in the refrigeration cycle apparatus. However, chlorofluorocarbons have the property of destroying the ozone layer, have a long life in the atmosphere, and have a large greenhouse effect, so they have a great influence on global warming and could not be said to be satisfactory refrigerants. .

  Therefore, a refrigeration cycle apparatus that uses carbon dioxide, ethane, or the like as a refrigerant has been proposed instead of chlorofluorocarbons, which has an ozone depletion coefficient of zero and a global warming coefficient that is much smaller than that of chlorofluorocarbons. (For example, refer to Patent Document 3). A refrigerant such as carbon dioxide or ethane has a low critical temperature, and condensation does not occur on the high pressure side (compressor outlet-radiator-decompressor inlet) of a conventional refrigeration cycle device, so a supercritical cycle operated at a critical pressure or higher. It becomes. Therefore, the pressure on the high-pressure side can be arbitrarily adjusted regardless of the condensation temperature of the refrigerant, and is usually adjusted to a pressure at which the efficiency of the refrigeration cycle apparatus is optimal.

As the compressor, a scroll compressor as shown in FIG. 12 is used. FIG. 12 is a cross-sectional view of a conventionally used scroll compressor. The fixed scroll 101 and the orbiting scroll 102 where the spiral wrap rises from the end plate are engaged with each other to form a compression chamber 103 therebetween, and the orbiting scroll 102 is rotated. The refrigerant is sucked, compressed, and discharged by moving the compression chamber 103 while changing its volume when it is swung along a circular orbit under the restraint of rotation by the restraining mechanism 104. Between the orbiting scroll 102 and the fixing member 105 that backs up the back side of the orbiting scroll 102, a high pressure portion 106 that applies high pressure by lubricating oil is provided at the center of the back surface of the orbiting scroll 102. Is provided with a back pressure chamber 108 for applying a predetermined pressure (back pressure) lower than that of the high pressure portion 106 to the outer peripheral portion of the back surface, and the orbiting scroll 102 is fixed by these high pressure and back pressure. By pressing against the scroll component 101, the orbiting scroll 102 is prevented from falling over from the fixed scroll component 101 (see, for example, Patent Document 4).
JP-A-4-55671 JP 2005-133958 A Japanese Patent Publication No. 7-18602 Japanese Patent Laid-Open No. 2002-266776

  However, in the determination method described in Patent Document 1 (a method of determining that the refrigerant leaks when the discharged refrigerant temperature exceeds a predetermined value), a refrigerant (for example, carbon dioxide) that is operated exceeding the critical pressure is used. In this case, since the degree of increase in the discharge refrigerant temperature at the time of refrigerant shortage is small, it is not possible to determine the refrigerant shortage and to ensure reliability.

  Further, in the determination method described in Patent Document 2 (a method of determining that the refrigerant is insufficient when the difference between the target temperature of the fluid and the detected temperature of the fluid flowing out of the radiator is equal to or higher than a predetermined temperature), the scroll compressor is used. Even if the capsizing phenomenon occurs in the used refrigeration cycle, the refrigerant circulation amount is insufficient and the refrigeration capacity is lowered, the desired fluid temperature cannot be detected, and only the capsizing phenomenon occurs. However, although the refrigerant is not insufficient, there is a problem that it is determined that the refrigerant is insufficient.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a refrigeration cycle apparatus that can reliably determine the shortage of refrigerant.

In order to solve the above-described conventional problems, the refrigeration cycle apparatus of the present invention uses a refrigerant that is operated at a critical pressure or higher, and at least a scroll compressor, a radiator, a decompressor, and an evaporator are sequentially arranged in a refrigerant pipe. A refrigeration cycle connected to the compressor, a discharge temperature detecting means for detecting a temperature of refrigerant discharged from the compressor, a target discharge temperature setting means for setting a target discharge temperature of refrigerant discharged from the compressor, and the heat dissipation A radiator fluid outlet temperature detecting means for detecting a temperature of the fluid after heat exchange with the refrigerant in the radiator, and a radiator fluid outlet temperature setting for setting a target temperature of the fluid after heat exchange with the refrigerant in the radiator Means, fluid conveying means for conveying the fluid to the radiator, circulation amount control means for controlling the circulation amount of the fluid conveyed by the fluid conveying means, and pressure reducing device control means for controlling the pressure reducing device. The decompression device controlling means, the temperature detected by the discharge temperature detecting means, controls the pressure reducing device so that the set target discharge temperature at the target discharge temperature setting means, wherein circulation quantity control means The refrigeration cycle apparatus for controlling the fluid conveying means such that the temperature detected by the radiator fluid outlet temperature detecting means becomes a target temperature set by the radiator fluid outlet temperature setting means, wherein the fluid The circulating amount of the fluid conveyed by the conveying means is less than the predetermined value α, the difference between the fluid temperature at the radiator outlet and the target temperature is equal to or larger than the predetermined value β, and is discharged from the compressor. Determining that the amount of refrigerant circulating in the refrigeration cycle is insufficient when the difference between the refrigerant discharge temperature and the fluid temperature detected by the radiator fluid outlet temperature detection means is equal to or greater than a predetermined value γ. The It is an butterfly.

  This prevents erroneous determination of refrigerant shortage and makes it possible to reliably determine refrigerant shortage and prevent damage to the compressor and deterioration of the reliability of the refrigeration cycle apparatus.

  The refrigeration cycle apparatus of the present invention can reliably determine the shortage of refrigerant.

The refrigeration cycle apparatus of the first invention uses a refrigerant operated at a critical pressure or higher, and at least a scroll compressor, a radiator, a decompression device, and an evaporator are sequentially connected in an annular manner through a refrigerant pipe, The discharge temperature detecting means for detecting the temperature of the refrigerant discharged from the compressor, the target discharge temperature setting means for setting the target discharge temperature of the refrigerant discharged from the compressor, and heat exchange with the refrigerant by the radiator A radiator fluid outlet temperature detecting means for detecting the temperature of the subsequent fluid, a radiator fluid outlet temperature setting means for setting a target temperature of the fluid after heat exchange with the refrigerant in the radiator, and a fluid in the radiator Fluid conveying means for conveying the fluid, circulation amount control means for controlling the circulation amount of the fluid conveyed by the fluid conveying means, and pressure reducing device control means for controlling the pressure reducing device, wherein the pressure reducing device control means comprises: Previous Temperature detected by the discharge temperature detecting means, controls the pressure reducing device so that the set target discharge temperature at the target discharge temperature setting means, wherein circulation quantity control means, wherein the radiator fluid outlet temperature detector A refrigeration cycle apparatus for controlling the fluid conveying means so that a temperature detected by the means becomes a target temperature set by the radiator fluid outlet temperature setting means, wherein the fluid conveyed by the fluid conveying means The circulation amount is less than the predetermined value α, the difference between the fluid temperature at the outlet of the radiator and the target temperature is not less than the predetermined value β, and the discharge temperature of the refrigerant discharged from the compressor and the radiator When the difference from the fluid temperature detected by the fluid outlet temperature detection means is equal to or greater than a predetermined value γ, it is determined that the amount of refrigerant circulating in the refrigeration cycle is insufficient. Prevention Rutotomoni reliably enables determination of the refrigerant shortage, damage to the compressor, it is possible to prevent a decrease in reliability of the refrigeration cycle apparatus.

  The refrigeration cycle apparatus according to the second invention is the refrigeration cycle apparatus according to the second invention, particularly in the first invention, further comprising current detection means for detecting an energization current of the refrigeration cycle apparatus, wherein the current value detected by the current detection means is less than a predetermined value I. If it is determined that the amount of refrigerant circulating in the refrigeration cycle is insufficient, it can be surely added to the criteria for determining refrigerant shortage without erroneous determination during high-load operation of the compressor. It is possible to determine whether the refrigerant is insufficient.

  The refrigeration cycle apparatus according to a third aspect of the invention is particularly provided in the first or second aspect of the invention, further comprising a decompression device opening direction determining means for determining an opening direction of the decompression apparatus, wherein the decompression direction determination means performs the decompression If it is determined that the opening direction of the apparatus is operating in the opening direction, it is determined that the amount of refrigerant circulating through the refrigeration cycle is insufficient, so that the refrigeration cycle after the execution of protection control is stabilized. It is possible to reliably determine the lack of refrigerant without making an erroneous determination in the case where it is not performed.

  The refrigeration cycle apparatus according to a fourth aspect of the invention is particularly any one of the first to third aspects of the invention, further comprising a defrosting operation determining means for determining whether or not the refrigeration cycle apparatus is in a defrosting operation, If the defrosting operation determination means determines that the refrigeration cycle apparatus is not in the defrosting operation, it is erroneously determined during the defrosting operation by determining that the amount of refrigerant circulating in the refrigeration cycle is insufficient. It is possible to reliably determine whether the refrigerant is insufficient.

  In the refrigeration cycle apparatus of the fifth invention, in particular, in any one of the first to fourth inventions, the use of carbon dioxide as the refrigerant can reduce the product cost and improve the reliability. Carbon dioxide has an ozone depletion coefficient of zero and a global warming coefficient of about 1/700 that of the alternative refrigerant HFC-407C, which makes it possible to provide a product that is friendly to the global environment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a hot water supply apparatus which is an example of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. The hot water supply apparatus according to the first embodiment includes a heat pump unit A and a hot water storage unit B. At least the inverter-type scroll compressor 11, the refrigerant flow path 12a of the radiator 12, the decompression device 13, and the evaporator 14 are connected to the refrigerant pipe. And a refrigerating cycle sequentially connected in an annular manner, and a blower fan 17 for blowing outside air to the evaporator 14. Carbon dioxide whose critical pressure exceeds the critical pressure is used as the refrigerant for the refrigeration cycle. Further, the scroll compressor 11 has a compressor configuration without an accumulator, and since there is no accumulator, the refrigeration cycle apparatus main body can be reduced in size and weight.

  Further, the hot water storage tank 16 for storing hot water, the fluid flow path 12b of the radiator 12, and the liquid (water in this embodiment) stored in the hot water storage tank 16 are conveyed to the fluid flow path 12b of the radiator 12. A water pump 15 serving as a fluid conveying means, and the water in the lower part of the hot water storage tank 16 is transported to the fluid flow path 12b by driving the water pump 15, and hot water is generated by the radiator 12, Hot water is stored on the stack from above the tank 16. Further, in the radiator 12, the refrigerant flow path 12a and the fluid flow path 12b form a counter flow, enabling efficient heat exchange.

  Further, in the refrigeration cycle, the refrigerant discharge port of the scroll compressor 11 is provided with discharge temperature detection means 41 for detecting the temperature of the discharge refrigerant (hereinafter referred to as discharge refrigerant temperature), while the fluid of the radiator 12 A radiator fluid outlet temperature detecting means 21 for detecting the temperature of hot water discharged from the flow path 12b (hereinafter referred to as a hot water temperature detection value) is provided.

  Further, the temperature on the outlet side of the fluid flow path 12b (hereinafter referred to as the hot water temperature) from the outside air temperature, the temperature on the inlet side of the fluid flow path 12b (hereinafter referred to as the incoming water temperature), the remote control setting by the user, and the like. Is provided with a radiator fluid outlet temperature setting means 22 for calculating and setting a target value (hereinafter referred to as a tapping temperature target value).

  Further, according to the hot water temperature detection value and the hot water temperature target value, the circulation amount control means 23 that calculates and controls the rotation speed of the water pump 15 and the circulation that flows through the fluid flow path 12b from the rotation speed instruction value to the water pump 15. Circulation amount detection means 24 for estimating the amount is provided.

  Further, a radiator outlet fluid temperature difference calculating means 25 for calculating a difference between the tapping temperature target value set by the radiator fluid outlet temperature setting means 22 and the tapping temperature detected value is provided.

  In addition, a driving unit 31 that drives the scroll compressor 11 is provided, and a current detection unit 32 that detects an energization current from the driving unit 31 to the scroll compressor 11 is provided.

  Further, it is set by a decompression device target opening degree setting means 42 for calculating and setting the first target value of the opening degree of the decompression device 13 from the outside air temperature, the incoming water temperature, etc., and a target discharge temperature setting means (not shown). A second target value of the opening of the decompression device 13 that matches the discharge refrigerant temperature to the target discharge temperature is calculated, and the target value of one of the first target value or the second target value is selected to reduce the pressure. A decompression device control means 43 for operating the opening degree of the device 13 is provided.

  Further, the first target value and the second target value of the opening of the decompression device 13 (or the opening of the decompression device 13 actually operated by the decompression device control means 43) are compared, and the opening of the decompression device 13 is compared. Is provided with a decompression device opening direction determination means 44 for determining whether the adjustment is in the opening direction or the adjustment in the closing direction.

  Moreover, the temperature difference calculating means 45 which calculates the temperature difference of discharge refrigerant temperature and tapping temperature target value is provided, and the defrost operation determination means 51 which determines whether the refrigeration cycle apparatus is in defrost operation is provided. ing.

  And some signals from the circulation amount detecting means 24, the radiator outlet fluid temperature difference calculating means 25, the current detecting means 32, the decompression device opening direction determining means 44, the temperature difference calculating means 45, and the defrosting operation determining means 51. Is provided with a refrigerant shortage determining means 61 for determining the refrigerant shortage.

  The operation of the refrigeration cycle apparatus configured as described above will be described below. When the scroll compressor 11 constituting the refrigeration cycle compresses carbon dioxide, which is a refrigerant, to a pressure exceeding the critical pressure, the compressed refrigerant becomes a high temperature / high pressure state and flows through the refrigerant flow path 12a of the radiator 12. Radiates heat to the water flowing through the fluid flow path 12b.

  Then, the refrigerant cooled by the radiator 12 is decompressed by the decompression device 13, enters a low-temperature / low-pressure gas-liquid two-phase state, and enters the evaporator 14. In the evaporator 14, the refrigerant is heated by the outside air sent by the blower fan 17, enters a gas-liquid two-phase or gas state, and is sucked into the scroll compressor 11 again.

  On the other hand, the water sent from the bottom of the hot water storage tank 16 to the fluid flow path 12b of the radiator 12 by the water pump 15 is heated by the high-temperature refrigerant flowing through the refrigerant flow path 12a to become hot hot water, and from above the hot water storage tank 16 Save up.

  By repeating the above operation, hot water is stored in the hot water storage tank 16 so that the temperature distribution is formed in a stacked manner from the top to the bottom. A hot water supply port for supplying water from a water supply source is provided at the bottom of the hot water storage tank 16, and a hot water supply port for supplying hot water to the hot water supply terminal is provided at the upper portion of the hot water storage tank 16.

  Next, control of the decompression device 13 will be described. For the purpose of improving the responsiveness of the decompression device 13, when the refrigeration cycle is not stable at the time of starting or the like, the decompression device control means 43 is set to the first target value set by the decompression device target opening setting means 42. When the opening degree of the decompression device 13 is adjusted (feed forward control) and the refrigeration cycle is stable, the decompression device control means 43 is discharged from the scroll compressor 11 detected by the discharge temperature detection means 41. The opening degree of the decompression device 13 is adjusted (feedback control) so that the decompression device control means 43 has the second target value calculated and set so that the refrigerant temperature becomes a predetermined target discharge temperature. Yes.

  Further, the circulation amount control means 23 is controlled by feedback control so that the detected hot water temperature detected by the radiator fluid outlet temperature detecting means 21 becomes the hot water temperature target value set by the radiator fluid outlet temperature setting means 22. By adjusting the rotation speed of the water pump 15 and adjusting the circulation amount of the water flowing through the fluid flow path 12 b of the radiator 12, the hot water having a constant temperature is controlled to be stored in the hot water storage tank 16.

  Next, the operation of the refrigerant shortage determination due to refrigerant leakage or the like will be described using the flowchart of FIG.

The operation of the scroll compressor 11 is started, and after a predetermined time has elapsed, the elapsed time measurement value t is reset, and the measurement of the elapsed time is started again. (Step 101)
Next, the circulation amount Gw of the fluid (hot water) is detected by the circulation amount detection means 24. (Step 102) In the present embodiment, the circulation amount is not directly detected, but the circulation amount is estimated from the number of revolutions instructed to the water pump 15 by the circulation amount control means 23.

  Next, a comparison is made as to whether or not the detected circulation amount Gw is less than a predetermined circulation amount α to determine whether the fluid circulation amount Gw is equal to the predetermined circulation amount α. (Step 103) If Gw ≧ α, the process returns to Step 101. If Gw <α, the process proceeds to Step 104.

Next, the tapping temperature Tw is detected by the radiator fluid outlet temperature detection means 21 (for example, a temperature sensor provided on the pipe for detecting the temperature of the pipe or a temperature sensor provided in the pipe for directly detecting the water temperature). (Step 104)
Next, a temperature difference ΔTw between the detected hot water temperature Tw and a hot water temperature target value Tw0 determined in advance by the radiator fluid outlet temperature setting means 22 is calculated. (Step 105)
Next, a comparison is made as to whether ΔTw is equal to or greater than β set in advance, and it is determined whether the tapping temperature reaches a tapping temperature target value. (Step 106) If ΔTw <β, the process returns to Step 101. If ΔTw ≧ β, the process proceeds to Step 107.

Next, the discharge refrigerant temperature Td is detected by the discharge temperature detection means 41 (for example, a temperature sensor that detects the temperature of a pipe provided on the pipe). (Step 107)
Next, a temperature difference ΔTd between the detected discharged refrigerant temperature Td and the tapping temperature target value Tw0 determined in advance by the radiator fluid outlet temperature setting means 22 is calculated. (Step 108)
Next, a comparison is made as to whether the temperature difference ΔTd is equal to or greater than a predetermined value γ. If ΔTd ≧ γ, the process proceeds to step 110, and if ΔTd <γ, the process returns to step 101. (Step 109)
Next, it is determined whether or not the elapsed time measurement value t is equal to or greater than a predetermined time t0. (Step 110) Here, in order to prevent erroneous detection of each detection means, it is determined whether or not the conditions of Steps 103, 106, and 109 are continuously established for a certain time, and the elapsed time t When the predetermined time t0 or more has elapsed, the routine proceeds to step 111, and when it has not elapsed, the routine returns to step 102.

  It is determined whether or not the above conditions of Steps 103, 106, and 109 are continuously established for a certain period of time. If the predetermined time is satisfied, the refrigerant shortage determining means 61 determines that the refrigerant is in a shortage state. In addition, an abnormality is displayed on a display device (not shown) such as a remote controller, and the scroll compressor 11 is stopped to prevent the inverter-type scroll compressor 11 from being deteriorated in reliability such as damage.

  Next, the movement of the refrigeration cycle when the refrigerant becomes insufficient will be described. FIG. 3 shows the number of rotations of the water pump 15 corresponding to the amount of refrigerant. In FIG. 3, the refrigerant amount ratio on the horizontal axis is the ratio of the refrigerant amount when the refrigerant is insufficient with respect to the appropriate refrigerant amount. That is, the refrigerant amount ratio of 50% indicates that the refrigerant amount is only 50% with respect to the appropriate refrigerant amount. The vertical axis indicates the hot water temperature detection value and the hot water temperature target value, and the right axis indicates the ratio with respect to the rotation speed of the water pump at an appropriate amount of refrigerant. The circulation rate ratio of 80% indicates that only the rotation speed of 80% of the rotation speed of the water pump is output when the refrigerant amount is appropriate. In addition, the figure shown in FIG. 3 shows about one Example of a refrigerating-cycle apparatus, It is not limited to this.

  Generally, when the refrigerant shortage occurs, the circulation amount of the refrigerant discharged from the scroll compressor 11 is insufficient, and the heating capacity in the radiator 12 is reduced. However, as described above, since the circulating amount of the fluid is adjusted by the water pump 15 so that the detected hot water temperature value becomes the target hot water temperature value, as shown in FIG. (If shown in FIG. 3, it is possible to maintain the tapping temperature at the target value by reducing the circulation rate of water up to the refrigerant amount of up to 40 to 50% refrigerant ratio).

  However, when the refrigerant amount becomes less than that, the rotation speed of the water pump 15 becomes the minimum rotation speed, and the circulation amount of water cannot be further reduced, and the hot water temperature detection value and the hot water temperature target value Therefore, when the temperature difference between the hot water temperature detection value and the hot water temperature target value increases more than a predetermined temperature, it can be said that it is one of the criteria for refrigerant leakage determination.

  The effects of the refrigeration cycle apparatus configured or controlled as described above will be described. FIG. 4 shows a change in the high-pressure side pressure when the refrigerant runs short in a state where the heat (heat radiation capacity) given from the refrigerant to the water in the radiator 12 is controlled to be constant. As shown in FIG. 4, when carbon dioxide (CO2) is used, the degree of decrease in the high-pressure side pressure when the refrigerant is insufficient is larger than when R410A, which is a conventional refrigerant, is used. This can be explained from the movement of the refrigeration cycle shown on the pressure / enthalpy diagram when the refrigerant is insufficient (broken line, one-dot chain line) from the appropriate refrigerant amount (solid line) shown in FIGS. As shown in FIG. 5, when carbon dioxide (CO 2) is used, a supercritical cycle occurs when the amount of refrigerant is adequate (solid line) or when there is a shortage of refrigerant (dashed line). Further, even when the refrigerant is largely insufficient (dashed line), most of the change in the enthalpy on the high pressure side is a change in the gas region rather than the two-phase region. For this reason, since the refrigerant temperature difference between the inlet and the outlet in the refrigerant flow path 12a of the radiator 12 is large (temperature gradient is large), the temperature of the water flowing through the fluid flow path 12b is low even if the high-pressure side pressure is low. Since the difference can be secured, sufficient heat exchange can be performed (heating capacity can be secured). On the other hand, as shown in FIG. 6, when R410A, which is a conventional refrigerant, is used, most of the change in enthalpy on the high pressure side is a change in the two-phase region, so the temperature of the water flowing through the fluid flow path 2b In order to ensure the difference, the pressure becomes a high-pressure side pressure corresponding to a relatively high condensation temperature, and even if the refrigerant is insufficient, the high-pressure side pressure does not drop significantly.

  That is, when carbon dioxide is used, the high pressure side pressure is greatly reduced when the refrigerant is insufficient due to the supercritical cycle in which the high pressure side pressure is determined regardless of the condensation temperature. Further, FIG. 7 shows an increase in the discharge temperature when the refrigerant is insufficient with a difference from the discharge temperature at an appropriate refrigerant amount in a state where the heat given from the refrigerant to the water in the radiator 12 is controlled to be constant. ing. As shown in FIG. 7, when carbon dioxide (CO2) is used, even when the suction superheat degree and the discharge temperature are not controlled to be constant, the refrigerant is compared with the conventional refrigerant R410A. It can be seen that the degree of increase in the discharge temperature at the time of shortage is small. As described with reference to FIG. 4, when carbon dioxide (CO 2) is used, the decrease in the high-pressure side pressure is large, and accordingly the degree of increase in the discharge temperature is also small. Note that when the decompressor 13 is controlled so as to keep the suction superheat degree constant, or when the decompressor 13 is controlled so as to keep the discharge temperature constant as in the present embodiment, the discharge The rise in temperature is further suppressed. Therefore, when a refrigerant that can be in a supercritical state on the high pressure side, such as carbon dioxide, is used as the refrigerant, it is difficult to determine whether the refrigerant is insufficient due to an increase in the discharge temperature as in the past.

  However, the refrigerant shortage determination method as shown in Patent Document 2 (the refrigerant is short when the circulating amount of the fluid is less than a predetermined value and the temperature difference between the hot water temperature detection value and the hot water temperature target value is greater than or equal to the predetermined value). If the temperature difference between the tapping temperature detection value and the tapping temperature target value is equal to or greater than a predetermined value, the temperature between the tapping temperature detection value and the tapping temperature target value is also the same during the overturning phenomenon. The difference may increase by a predetermined value or more, and it is determined that the refrigerant is insufficient even though the refrigerant is not insufficient.

  Therefore, in the present invention, the determination in step 109 is performed to reliably distinguish between the refrigerant shortage and the overturning phenomenon, and more accurately determine the refrigerant shortage.

FIG. 8 is a diagram showing the discharged refrigerant temperature and the tapping temperature when the overturning phenomenon occurs. In FIG. 8, it can be seen that when the overturning phenomenon occurs, the discharge refrigerant temperature and the hot water temperature are significantly lower than the target discharge temperature and the hot water temperature target value. That is, the circulating amount of fluid is less than a predetermined value, and the hot water temperature detection value may not reach the hot water temperature target value.

  On the other hand, the capacity decreases when the refrigerant is insufficient, but the discharged refrigerant temperature does not decrease so much as compared to the time when the capsize phenomenon occurs. Therefore, if the temperature difference between the discharged refrigerant temperature (refrigerant temperature) and the hot water temperature detection value (fluid temperature) is equal to or greater than the predetermined value γ, it can be determined that the refrigerant is insufficient and that the refrigerant is insufficient.

  As described above, it is possible to accurately determine the overturning phenomenon and the refrigerant shortage by setting the temperature difference between the discharged refrigerant temperature and the tapping temperature detection value to be equal to or greater than the predetermined value γ as one of the criteria for the refrigerant shortage determination. Therefore, a refrigeration cycle apparatus with high usability can be provided.

(Embodiment 2)
A hot water supply apparatus that is a refrigeration cycle apparatus according to a second embodiment of the present invention will be described. Since the schematic configuration of the present embodiment is the same as that of FIG. 1, description of the configuration and the operation of the refrigeration cycle is omitted.

  The control operation when the refrigerant is insufficient due to refrigerant leakage or the like will be described with reference to the flowchart of FIG. In FIG. 9, the same steps as those in FIG. After performing steps 101 to 109, the energization current is detected by the current detection means 32 (for example, a current sensor that detects the current energized from the inverter circuit as the drive means 31 to the compressor 11) (step 201). The detected energization current value I is compared with a predetermined current value I0 (step 202), and it is determined whether or not the compressor 11 is in a high load state. If the energization current value I is less than the predetermined value I0, the process proceeds to the next step, and if it is greater than the set value I0, the process returns to step 101. Thereafter, step 110 is performed. Therefore, the circulation amount of water is less than a predetermined value, the tapping temperature does not reach the tapping temperature target value, and the temperature difference between the discharge temperature and the radiator fluid target temperature is not less than a predetermined value. If the condition that the energization current is less than a predetermined value is satisfied for a certain period of time, the refrigerant shortage determination means 61 determines that the refrigerant is in a shortage state and displays an indicator (not shown) such as a remote controller. 2), the scroll compressor 11 is stopped (step 111), and deterioration of the reliability of the refrigeration cycle apparatus such as damage to the scroll compressor 11 is prevented.

  Next, the movement of the refrigeration cycle when the refrigerant becomes insufficient will be described. When the refrigerant shortage occurs, the circulation amount of the refrigerant discharged from the scroll compressor 11 is insufficient, and the heating capacity in the radiator 12 is reduced. In addition, since the compressor 11 has a low load due to a short circulation amount of the refrigerant, the energization current to the compressor 11 decreases. For this reason, the circulation amount of water is less than a predetermined value, the tapping temperature does not reach the tapping temperature target value, and the temperature difference between the discharge temperature and the radiator fluid target temperature is equal to or greater than the predetermined value. When the energization current detected by the current detection means 32 is less than a predetermined value, it can be determined that the refrigerant is in a shortage state.

  On the other hand, even when the refrigerant is not insufficient, for example, during operation at a low outside air temperature, the amount of water circulation is less than a predetermined value, and the tapping temperature reaches the tapping temperature target value. There may not be. However, in this case, since the scroll compressor 11 is operated at a high load, the energization current is not reduced but rather increases. Therefore, the current detection value detected by the current detection unit 32 becomes equal to or greater than a predetermined value, and the refrigerant shortage determination unit 61 continues energization of the scroll compressor 11 and continues its operation without determining refrigerant shortage. . For this reason, in the present embodiment, it is possible to prevent the refrigerant shortage from being erroneously determined during high-load operation of the scroll compressor, and to detect the refrigerant shortage more accurately.

The current detection means 32 detects the energization current to the compressor 11. However, the current detection means 32 detects the energization current to the entire refrigeration cycle apparatus including the energization current to the blower fan 17 and the water pump 15. However, since the energization current to the scroll compressor 11 occupies most of the energization current to the entire refrigeration cycle apparatus, the same effect can be obtained.

  The predetermined current value I0 may be set to a plurality of values corresponding to the operating frequency of the scroll compressor 11.

(Embodiment 3)
A hot water supply apparatus that is a refrigeration cycle apparatus according to a third embodiment of the present invention will be described. Since the schematic configuration of the present embodiment is the same as that of FIG. 1, description of the configuration and the operation of the refrigeration cycle is omitted.

  The control operation when the refrigerant is insufficient due to refrigerant leakage or the like will be described with reference to the flowchart of FIG. In FIG. 10, the same steps as those in FIG. After performing steps 101 to 109, the decompressor opening direction determining means 44 calculates the feedforward control target value (target decompressor opening 1) PLS1 calculated by the decompressor target opening calculating means 42 by itself. Comparison with the target value (target decompressor opening 2) PLS2 of the feedback control is performed (step 301), and it is determined whether the decompressor 13 is being adjusted in the opening direction or in the closing direction. . When the decompressor 13 is being adjusted in the opening direction, the process proceeds to the next step. When the decompressor 13 is being adjusted in the closing direction, the process returns to step 101. Thereafter, step 110 is performed. Therefore, the circulation amount of water is less than a predetermined value, the tapping temperature does not reach the tapping temperature target value, and the temperature difference between the discharge temperature and the radiator fluid target temperature is not less than a predetermined value. If the condition that the decompressor 13 is being adjusted in the opening direction is satisfied for a certain period of time, the refrigerant shortage determining means 61 determines that the refrigerant is in shortage and displays a display such as a remote controller (not shown). 2), the scroll compressor 11 is stopped (step 111), and deterioration of the reliability of the refrigeration cycle apparatus such as damage to the scroll compressor 11 is prevented.

  Next, the movement of the refrigeration cycle when the refrigerant becomes insufficient will be described. When the refrigerant shortage occurs, the circulation amount of the refrigerant discharged from the scroll compressor 11 is insufficient, the heating capacity in the radiator 12 is lowered, and the discharge temperature is increased. However, when the refrigeration cycle is stable, the decompressor opening degree calculation operation means 43 causes the discharge temperature of the scroll compressor 11 detected by the discharge temperature detection means 41 to be a predetermined target discharge temperature. The opening of the decompressor 13 is adjusted (feedback control) to the target decompressor opening 2 calculated by itself. That is, since the discharge temperature tends to increase in a state where the refrigerant is insufficient, the decompressor 13 is to be adjusted in the opening direction. Here, the target value (target decompressor opening 2) of the feedback control calculated based on the state of the refrigeration cycle when the refrigerant is insufficient is a feed calculated based on the state of the refrigeration cycle with an appropriate amount of refrigerant. Since the value is larger than the target value of the forward control (target decompressor opening 1), the opening direction of the decompressor 13 can be determined by comparing these values.

Therefore, the circulation amount of water is less than a predetermined value, the tapping temperature does not reach the tapping temperature target value, and the temperature difference between the discharge temperature and the radiator fluid target temperature is not less than a predetermined value. If the decompressor 13 is being adjusted in the opening direction, it can be determined that the refrigerant is insufficient. On the other hand, for example, the decompressor 13 may be largely adjusted in the opening direction by protection control based on the high-pressure side pressure or the discharge temperature. In this case, when the protection control is canceled by opening the decompressor 13 wide, the decompressor 13 is adjusted in the closing direction by the decompressor opening degree operation means 43 so that the discharge temperature becomes constant again. Therefore, even if the refrigerant is not insufficient, the decompressor 13 is largely adjusted in the opening direction by protection control or the like, so that the circulation amount of water is less than a predetermined value, and the tapping temperature is the tapping temperature. Although the target value may not be reached, in this case, since the decompressor 13 is being adjusted in the closing direction, the refrigerant shortage determining means 61 does not determine whether the refrigerant is insufficient, and does not energize the compressor 11. Continue and continue the operation. Therefore,
In the present embodiment, when the refrigeration cycle after the implementation of protection control or the like is not stable, it is possible to prevent the refrigerant shortage from being erroneously determined, and to detect the refrigerant shortage more accurately.

  The decompressor opening direction determining means 44 compares the target value of feedforward control (target decompressor opening 1) with the target value of feedback control (target decompressor opening 2) to open the decompressor 13. Whether the pressure reducer 13 is being adjusted in the opening direction by comparing the opening of the pressure reducer 13 a certain time ago with the current opening of the pressure reducer 13, for example. Alternatively, it may be determined whether the adjustment is being made in the closing direction. Moreover, you may perform correction | amendment, such as adding a fixed value to the target decompressor opening degree 1 and the target decompressor opening degree 2, and multiplying.

Further, the decompressor 13 has been described as being controlled so that the discharge temperature is constant, but even when the suction superheat degree of the compressor 11 and the outlet superheat degree of the evaporator 14 are controlled to be constant, Similar effects can be obtained.
(Embodiment 4)
A hot water supply apparatus that is a refrigeration cycle apparatus according to a fourth embodiment of the present invention will be described. Since the schematic configuration of the present embodiment is the same as that of FIG. 1, description of the configuration and the operation of the refrigeration cycle is omitted.

  The control operation when the refrigerant is insufficient due to refrigerant leakage or the like will be described with reference to the flowchart of FIG. In FIG. 11, steps similar to those in FIG. Before performing step 101, it is determined whether the refrigeration cycle is in a defrosting operation (step 401). When the refrigeration cycle is not in the defrosting operation, the process proceeds to the next step, and when it is in the defrosting operation, the process returns to step 401. Thereafter, steps 101 to 109, 201 and 202, 110 are performed. Therefore, the circulation amount of water is less than a predetermined value, the hot water temperature does not reach the hot water temperature target value, and the temperature difference between the discharge temperature and the radiator fluid target temperature is equal to or greater than a predetermined value. If the condition is satisfied for a certain time, the refrigerant shortage determining means 61 determines that the refrigerant is in a shortage state, displays an abnormality on a display (not shown) such as a remote controller, and stops the scroll compressor 11. (Step 111), thereby preventing a decrease in the reliability of the refrigeration cycle apparatus such as damaging the scroll compressor 11.

  Even if it is not a shortage of refrigerant, because the defrosting operation is in progress, the circulation rate of water is less than a predetermined value, and the tapping temperature may not reach the tapping temperature target value. In this case, the refrigerant shortage determining means 61 continues energization of the scroll compressor 11 and continues its operation without determining refrigerant shortage. Therefore, in the present embodiment, it is possible to prevent the refrigerant shortage from being erroneously determined when the defrosting operation is being performed, and to detect the refrigerant shortage more accurately.

  As described above, the refrigeration cycle apparatus and the control method of the present invention use a refrigerant (for example, R32, carbon dioxide, ethane, ethylene, nitrogen oxide and a mixed refrigerant containing them) that can be in a supercritical state on the high pressure side as a refrigerant. In the used hot water supply device (hot water heater), air conditioner, and vehicle air conditioner (car air conditioner), the shortage of refrigerant can be reliably detected by an inexpensive method without impairing the reliability of the refrigeration cycle apparatus.

The block diagram which shows the refrigerating-cycle apparatus in Embodiment 1 of this invention. Flowchart showing the control method in the first embodiment Characteristic diagram at the time of refrigerant shortage in the first embodiment Comparison diagram of high pressure side pressure when refrigerant of R410A and CO2 is insufficient in the first embodiment Pressure and enthalpy diagram at the time of refrigerant shortage of CO2 in the first embodiment Pressure / enthalpy diagram at the time of refrigerant shortage of R410A in the first embodiment Comparison chart of discharge temperature rise degree when refrigerant of R410A and CO2 is insufficient in the first embodiment Characteristic diagram of discharge refrigerant temperature and tapping temperature at the time of occurrence of compressor overturn phenomenon in the first embodiment The flowchart which shows the control method in Embodiment 2 of this invention. The flowchart which shows the control method in Embodiment 3 of this invention. The flowchart which shows the control method in Embodiment 4 of this invention. Sectional view of a conventional scroll compressor

DESCRIPTION OF SYMBOLS 11 Scroll compressor 12 Radiator 13 Pressure reducing device 14 Evaporator 15 Water pump 16 Hot water storage tank 17 Blower fan 21 Radiator fluid outlet temperature detection means 22 Radiator fluid outlet temperature setting means 23 Circulation amount control means 24 Circulation amount detection means 25 Heat dissipation Unit outlet fluid temperature difference calculating means 31 Driving means 32 Current detecting means 41 Discharge temperature detecting means 42 Pressure reducing device target opening setting means 43 Pressure reducing device control means 44 Pressure reducing device opening direction determining means 45 Temperature difference calculating means 51 Defrosting operation determination Means 61 Refrigerant shortage determination means

Claims (5)

A refrigerant operated at a critical pressure or higher, a refrigeration cycle in which at least a scroll compressor, a radiator, a decompressor, and an evaporator are sequentially connected in an annular manner through a refrigerant pipe, and the temperature of the refrigerant discharged from the compressor are Discharge temperature detection means for detecting, target discharge temperature setting means for setting a target discharge temperature of the refrigerant discharged from the compressor, and a radiator for detecting the temperature of the fluid after heat exchange with the refrigerant by the radiator Fluid outlet temperature detection means, radiator heat outlet temperature setting means for setting a target temperature of the fluid after heat exchange with the refrigerant in the radiator, fluid conveying means for conveying fluid to the radiator, and the fluid a circulation quantity control means for controlling the circulation amount of the fluid to be conveyed by the conveying means, and a pressure reducing device controlling means for controlling the pressure reducing device, the decompression device controlling means, the temperature detected by the discharge temperature detecting means Is controlled so that the target discharge temperature is set by the target discharge temperature setting means, and the circulation amount control means is configured such that the temperature detected by the radiator fluid outlet temperature detection means is A refrigeration cycle apparatus for controlling the fluid conveying means so as to reach a target temperature set by a radiator fluid outlet temperature setting means, wherein the circulation amount of the fluid conveyed by the fluid conveying means is less than a predetermined value α. And the difference between the fluid temperature at the outlet of the radiator and the target temperature is a predetermined value β or more, and the discharge temperature of the refrigerant discharged from the compressor and the radiator fluid outlet temperature detection means are detected. A refrigeration cycle apparatus characterized by determining that the amount of refrigerant circulating in the refrigeration cycle is insufficient when a difference from a fluid temperature is equal to or greater than a predetermined value γ. In addition, current detection means for detecting an energization current of the refrigeration cycle apparatus is provided, and if the current value detected by the current detection means is less than a predetermined value I0, the amount of refrigerant circulating in the refrigeration cycle is insufficient. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is determined. Furthermore, it comprises pressure reducing device opening direction determining means for determining the opening direction of the pressure reducing device, and if the opening direction determining means determines that the opening direction of the pressure reducing device is operating in the open direction, The refrigeration cycle apparatus according to claim 1 or 2, wherein it is determined that the amount of refrigerant circulating in the cycle is insufficient. Furthermore, it is provided with a defrosting operation determination means for determining whether or not the refrigeration cycle apparatus is in a defrosting operation, and if the defrosting operation determination means determines that the refrigeration cycle apparatus is not in a defrosting operation, the refrigeration It is judged that the quantity of the refrigerant | coolant which circulates through a cycle is insufficient, The refrigeration cycle apparatus of any one of Claims 1-3 characterized by the above-mentioned. The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein carbon dioxide is used as a refrigerant.

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