JP6972370B2 - Refrigeration cycle device - Google Patents

Description

The present invention relates to a refrigeration cycle apparatus, and more particularly to a refrigeration cycle apparatus using a non-azeotropic mixed refrigerant.

Japanese Unexamined Patent Publication No. 6-12234 (Patent Document 1) discloses a refrigerating cycle apparatus capable of easily and accurately detecting the amount of refrigerant in a refrigerating cycle. In this refrigeration cycle device, a liquid level detection pipe equipped with a decompression means is provided in the container of the liquid receiver, and this is connected to the low pressure side pipe. Temperature detecting means are provided on the outlet side and low pressure side pipes of the depressurizing means, and the liquid level height of the receiver is detected from the detected refrigerant temperature.

Japanese Unexamined Patent Publication No. 6-12234

In JP-A-6-12234, it is determined based on the liquid state or the gas state whether the refrigerant sucked from the liquid level detection pipe provided in the liquid receiver (hereinafter, also referred to as a receiver) is in a liquid state or a gas state. It is determined whether the liquid level in the liquid receiver is higher or lower than the suction port of the liquid level detection pipe.

However, the suction port of the pipe for detecting the liquid level is in a fixed position. On the other hand, when the outside air temperature decreases, the refrigerant density during the refrigeration cycle decreases, so that the excess refrigerant enters the receiver and the liquid level of the receiver rises. Therefore, in order to avoid erroneous detection, the suction port of the pipe for detecting the liquid level is provided at the position when the refrigerant is considerably insufficient, and even if the refrigerant has decreased due to leakage or the like by then, it can be detected. There wasn't.

An object of the present invention is to provide a refrigerating cycle apparatus capable of accurately detecting a shortage of a refrigerant regardless of fluctuations in the outside air temperature.

The present disclosure relates to a refrigeration cycle apparatus using a non-azeotropic mixed refrigerant. The refrigeration cycle device includes a compressor, a first heat exchanger, a receiver, a first expansion device, a second heat exchanger, a compressor, a first heat exchanger, a receiver, a first expansion device, and a second. A refrigerant circuit that circulates the non-co-boiling mixed refrigerant in the order of the heat exchanger, and a bypass pipe that sends the non-co-boiling mixed refrigerant from the receiver to the suction port of the compressor without going through the first expansion device and the second heat exchanger. , A second expansion device provided in the bypass pipe is provided. A refrigerant inlet into which the non-azeotropic mixed refrigerant flows is provided at the end inserted into the receiver of the bypass pipe. The opening area of the refrigerant inlet is configured so that the amount of the non-azeotropic mixed refrigerant in the gas state flowing into the refrigerant inlet changes as the liquid level height of the receiver changes.

According to the present invention, even when the outside air temperature fluctuates, it is possible to detect a shortage of an appropriate amount of refrigerant at an early stage and with high accuracy.

It is a figure which shows the structure of the refrigerating cycle apparatus of Embodiment 1. FIG. It is a figure which shows the details of a receiver and piping. It is a ph diagram of a refrigerating cycle using a pseudo azeotropic refrigerant. It is a ph diagram of a refrigerating cycle using a non-azeotropic refrigerant. It is a flowchart for demonstrating the process of the refrigerant shortage detection of Embodiment 1. It is a figure which showed a plurality of holes provided in the bypass pipe of a receiver. It is a graph which shows the relationship between the dryness Q and the liquid level height H1. It is a graph which shows the relationship between a condensation temperature and an appropriate liquid level height. It is a figure which shows the structure of the 1st example of the suction end portion of a bypass pipe. In the first example, it is a figure for demonstrating the change of the total area of the opening which sucks a gas when the liquid level of the refrigerant in a receiver changes. It is a graph which showed the dryness corresponding to the change of the area of a hole of a gas part in 1st example. It is a graph which showed the relationship between the inlet dryness of a bypass pipe and the outlet temperature of a bypass pipe in the first example. It is a figure which shows the structure of the 2nd example of the suction end portion of a bypass pipe. It is a figure which shows the structure of the 3rd example of the suction end portion of a bypass pipe. It is a figure which shows the structure of the 4th example which inserted the end of the bypass pipe into a receiver from below. It is a figure which shows the structure of the suction end portion of the bypass pipe of 4th example. In the fourth example, it is a figure for demonstrating the change of the total area of the opening which sucks a gas when the liquid level of the refrigerant in a receiver changes. It is a graph which showed the dryness corresponding to the change of the area of the hole of a gas part in 4th example. It is a flowchart for demonstrating the process of the refrigerant shortage detection of Embodiment 2. It is a ph diagram for demonstrating superheat degree SH.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned from the beginning of the application to appropriately combine the configurations described in the respective embodiments. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

Embodiment 1.
In recent years, from the viewpoint of preventing global warming, in an air conditioner, a mixed refrigerant in which a refrigerant consisting of a single component is mixed with another refrigerant having a lower global warming potential (GWP) to lower the GWP. May be used. Among the mixed refrigerants, there are azeotropic refrigerants and non-azeotropic refrigerants.

The azeotropic refrigerant exhibits a constant boiling point when a plurality of component refrigerants are mixed at a certain ratio, and the compositions of the gas phase and the liquid phase are the same, and the phase changes as if they are one component. The azeotropic refrigerant has the same temperature at the same pressure during the phase change in a two-phase state, but the non-azeotropic refrigerant has a characteristic that the temperature changes during the phase change under the same pressure.

In the case of a refrigeration cycle device using a non-azeotropic refrigerant, it is possible to accurately detect a refrigerant shortage by utilizing the characteristics of the non-azeotropic refrigerant. The configuration of the refrigeration cycle device will be described below.

FIG. 1 is a diagram showing a configuration of a refrigeration cycle device according to the first embodiment. This refrigeration cycle device uses a non-azeotropic mixed refrigerant. It should be noted that FIG. 1 functionally shows the connection relationship and the arrangement configuration of each device in the refrigerating apparatus, and does not necessarily show the arrangement in the physical space.

With reference to FIG. 1, the refrigeration cycle device 1 includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 includes a compressor 10, a condenser 20, a fan 22, a receiver (receiver) 42, and pipes 80 to 84. Further, the outdoor unit 2 further includes a bypass pipe 85, a second expansion device 71, a temperature sensor 73, a first pressure sensor 90 and a second pressure sensor 92, and a control device 100. The second expansion device 71 is, for example, a capillary tube. The indoor unit 3 includes a first expansion device 50, an evaporator 60, a fan 62, and a pipe 83. The first expansion device 50 is, for example, an electronic expansion valve. The indoor unit 3 is connected to the outdoor unit 2 by pipes 82 and 84. The refrigerant circulates in the refrigerant circuit 110, and the bypass pipe 85 bypasses the refrigerant without passing through the first expansion device 50 and the evaporator 60.

The pipe 80 connects the discharge port of the compressor 10 and the condenser 20. The pipe 81 connects the condenser 20 and the receiver 42. The pipe 82 connects the receiver 42 and the first expansion device 50. The pipe 83 connects the first expansion device 50 and the evaporator 60. The pipe 84 connects the evaporator 60 and the suction port of the compressor 10. The bypass pipe 85 is composed of bypass pipes 86 and 87. The bypass pipe 86 connects the receiver 42 and the second expansion device 71. The bypass pipe 87 connects the second expansion device 71 and the pipe 84.

The compressor 10 sucks the refrigerant from the pipe 84, compresses the sucked refrigerant, and discharges the sucked refrigerant to the pipe 80. The compressor 10 is configured to adjust the rotation speed according to a control signal from the control device 100. By adjusting the operating frequency or rotation speed of the compressor 10, the circulation amount of the refrigerant is adjusted, and the capacity of the refrigerating cycle device 1 can be adjusted. Various types of compressors 10 can be adopted, and for example, scroll type, rotary type, screw type and the like can be adopted.

The condenser 20 condenses the refrigerant discharged from the compressor 10 to the pipe 80. The condensed refrigerant is sent to the pipe 81. The condenser 20 is configured such that a high-temperature and high-pressure gas refrigerant discharged from the compressor 10 exchanges heat (heat dissipation) with the outside air. By this heat exchange, the refrigerant is condensed and changed into a liquid phase. The fan 22 supplies the outside air to the condenser 20 through which the refrigerant exchanges heat in the condenser 20. By adjusting the rotation speed of the fan 22, the refrigerant pressure (high pressure side pressure) on the discharge side of the compressor 10 can be adjusted.

The receiver 42 stores the high-pressure liquid refrigerant condensed by the condenser 20. The first expansion device 50 decompresses the refrigerant sent from the receiver 42 to the pipe 82. The decompressed refrigerant is sent to the pipe 83. When the opening degree of the first expansion device 50 is changed in the closing direction, the refrigerant pressure on the low pressure side of the first expansion device 50 decreases, and the dryness of the refrigerant increases. When the opening degree of the first expansion device 50 is changed in the opening direction, the refrigerant pressure on the low pressure side of the first expansion device 50 increases, and the dryness of the refrigerant decreases.

The evaporator 60 evaporates the refrigerant sent from the first expansion device 50 to the pipe 83. The refrigerant that has passed through the evaporator 60 flows to the pipe 84. The evaporator 60 is configured such that the refrigerant decompressed by the first expansion device 50 exchanges heat (endothermic) with the air in the indoor unit 3. The refrigerant evaporates by passing through the evaporator 60 and becomes superheated steam. The fan 62 supplies air to the evaporator 60 through which the refrigerant exchanges heat in the evaporator 60.

As a configuration for detecting the refrigerant shortage, a bypass pipe 86, 87, a second expansion device 71 provided between the bypass pipes 86, 87, and a temperature sensor 73 are provided. The bypass pipe 86, the second expansion device 71, and the bypass pipe 87 form a bypass flow path that returns a part of the refrigerant that has passed through the condenser 20 to the compressor 10 without passing through the indoor unit 3. The second expansion device 71 is, for example, a capillary tube. The second expansion device 71 is connected between the bypass pipe 86 and the bypass pipe 87, and adjusts the flow rate of the refrigerant flowing in the bypass circuit. As the refrigerant passes through the second expansion device 71, the pressure of the refrigerant decreases.

The temperature sensor 73 is provided in the bypass pipe 87. The temperature sensor 73 detects the temperature T1 of the refrigerant that has passed through the second expansion device 71, and outputs the detected value to the control device 100. The temperature sensor 73 is installed inside the bypass pipe 87 in order to reliably detect the temperature of the refrigerant. The principle and method of detecting a refrigerant shortage using these will be described in detail later.

The first pressure sensor 90 detects the pressure LP of the refrigerant in the pipe 84 and outputs the detected value to the control device 100. That is, the first pressure sensor 90 detects the refrigerant pressure (low pressure side pressure) on the suction side of the compressor 10. The second pressure sensor 92 detects the pressure HP of the refrigerant in the pipe 80 and outputs the detected value to the control device 100. That is, the second pressure sensor 92 detects the refrigerant pressure (high pressure side pressure) on the discharge side of the compressor 10.

The control device 100 includes a CPU (Central Processing Unit) 102, a memory 104 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input / output buffer (not shown) for inputting / outputting various signals, and the like. Consists of including. The CPU 102 expands the program stored in the ROM into a RAM or the like and executes the program. The program stored in the ROM is a program in which the processing procedure of the control device 100 is described. The control device 100 executes control of each device of the refrigeration cycle device 1 according to these programs. This control is not limited to software processing, but can also be processed by dedicated hardware (electronic circuit).

FIG. 2 is a diagram showing details of the receiver and the piping. With reference to FIG. 2, a gas refrigerant and a liquid refrigerant are stored in the receiver 42. The refrigerant condensed by the condenser 20 flows in from the pipe 81. Liquid refrigerant flows out from the bottom of the receiver 42 from the pipe 82. The end opening of the pipe 82 is provided at a position lower than the end opening of the pipe 81 so that the liquid refrigerant preferentially flows out from the receiver 42 even if the refrigerant mixed with the gas flows in from the pipe 81. ing. The bypass pipe 86 is inserted from the upper part of the receiver 42 toward the inside. The bypass pipe 86 is provided with a plurality of openings on the side surface inside the receiver 42. With such a configuration, the dryness of the refrigerant sucked into the bypass pipe 86 changes depending on the liquid level height of the refrigerant in the receiver 42.

However, the lower end of the bypass pipe 86 needs to be provided at a position higher than that of the pipe 82 in order to prevent the gas refrigerant from flowing out from the pipe 82 due to a shortage of the refrigerant and the capacity of the refrigeration cycle is lowered. That is, when considering the height with respect to the bottom surface of the receiver 42, the lower end of the bypass pipe 86 is used to detect the refrigerant shortage before the liquid level height H1 of the liquid refrigerant drops below the height Hout1 of the outlet pipe. The height of Hout2 is higher than that of Hout1.

Next, the difference between the non-azeotropic refrigerant used in the present embodiment and the azeotropic refrigerant or the pseudo-azeotropic refrigerant will be described.

FIG. 3 is a ph diagram of a refrigeration cycle using a pseudo azeotropic refrigerant. FIG. 4 is a ph diagram of a refrigeration cycle using a non-azeotropic refrigerant.

Pseudo-azeotropic refrigerants show a certain boiling point when a plurality of component refrigerants are mixed at a certain ratio, and the composition in the gas phase and the liquid phase becomes the same, showing a phase change as if they were one component. .. R410A can be mentioned as an example of the pseudo azeotropic refrigerant. As shown in FIG. 3, the pseudo azeotropic refrigerant has an extremely small slope of the isotherm line in the two-phase region sandwiched between the saturated liquid line and the saturated steam line, and can be regarded as zero in design. Therefore, it can be considered that there is no gradient in the temperature of the two-phase region in the condenser and the temperature of the two-phase region in the evaporator.

In comparison, in the non-azeotropic refrigerant, the temperature of the non-azeotropic refrigerant changes during the phase change under the same pressure. R463A can be mentioned as an example of the non-azeotropic refrigerant. As shown in FIG. 4, the azeotropic refrigerant has a gradient in the isotherm in the two-phase region sandwiched between the saturated liquid line and the saturated steam line. Therefore, the temperature of the two-phase region in the condenser and the temperature of the two-phase region in the evaporator change depending on the dryness even under the same pressure.

In FIG. 4, the line segments AB show the state change of the refrigerant when flowing through the bypass flow path from the point A to the point B in FIG. The line segment AB indicates a case where the liquid level is high, that is, the dryness is small, and the line segment A'-B'indicates a case where the liquid level is low, that is, the dryness is high.

When the refrigerant is a non-azeotropic refrigerant, the enthalpy of the refrigerant at the point B can be specified by measuring the temperature T1 and the pressure LP at the point B in FIG. Since the second expansion device 71 performs adiabatic expansion, the enthalpy does not change. Therefore, the enthalpy of point A can be considered to be equal to the enthalpy of point B. In this way, the enthalpy of point A can be specified.

The pressure HP at point A is also measured by the second pressure sensor 92. If the pressure HP is known, the enthalpies of the saturated liquid line and the saturated vapor line at the same pressure can be specified in the ph diagram of FIG.

The degree of dryness is 0 if the position of point A in FIG. 4 is on the saturated liquid line and 1 if it is on the saturated steam line, and is determined by the position of point A between the saturated liquid line and the saturated steam line. From the above, in the case of the non-azeotropic refrigerant, the dryness of the point A can be obtained from the temperature T1, the pressure LP, and the HP. Therefore, it is possible to prepare in advance a map for obtaining the dryness of the point A from the temperature T1, the pressure LP, and the HP.

<Explanation of refrigerant shortage detection>
Hereinafter, a method for detecting a refrigerant shortage in the present embodiment will be described. The refrigerant shortage occurs when the initial filling amount of the refrigerant in the refrigerant circuit is insufficient, or when the refrigerant leaks after the start of use.

FIG. 5 is a flowchart for explaining the processing of the refrigerant shortage detection of the first embodiment. The process of this flowchart is repeatedly called from the main routine of control of the refrigeration cycle apparatus to check the amount of refrigerant.

With reference to FIG. 5, in step S1, the control device 100 detects the temperature T1 and the pressure LP at the point B which is the outlet of the capillary. Subsequently, in step S2, the control device 100 calculates the enthalpy of the point B. The enthalpy calculated here is equal to the enthalpy at point A, which is the entrance to the capillary.

Subsequently, the pressure HP can be detected in step S3, and the dryness of the point A can be calculated from the enthalpy obtained in step S2. In the above processing, as described with reference to FIG. 4, the dryness of the point A may be obtained from the temperature T1, the pressure LP, and the HP by using a map prepared in advance.

Subsequently, in step S4, the control device 100 calculates the receiver liquid level height H1 from the dryness of the point A.

FIG. 6 is a diagram showing a plurality of holes provided in the bypass pipe of the receiver. FIG. 7 is a graph showing the relationship between the dryness Q and the liquid level height H1. As the liquid level increases, the holes are closed with the liquid refrigerant, so that the gas refrigerant is less likely to be sucked and the dryness Q becomes smaller. On the contrary, as the liquid level becomes lower, the number of holes for sucking the gas refrigerant increases, so that the dryness Q becomes larger. The relationship between the dryness Q and the liquid level height H1 as shown in FIG. 7 can be obtained in advance and made into a map.

Returning to FIG. 5 again, after calculating the liquid level height H1 in step S4, the control device 100 calculates an appropriate liquid level height H2 with respect to the condensation temperature in step S5.

FIG. 8 is a graph showing the relationship between the condensation temperature and the appropriate liquid level. The condensation temperature can be known by measuring the pressure HP. The horizontal axis in FIG. 8 may be used as the pressure HP instead of the condensation temperature. The condensation temperature t is the condensation temperature when the condenser 20 exchanges heat with the outside air, and varies depending on the outside air temperature, the rotation of the fan 22, and the operating frequency of the compressor 10.

When the outside air temperature changes, the density of the refrigerant inside the condenser 20 changes, so that the amount of surplus refrigerant also changes, so that the liquid level height of the refrigerant in the appropriate receiver 42 also changes. Therefore, in order to accurately detect the refrigerant shortage at the initial stage of leakage, the reference height for comparing the liquid level height H1 in the current receiver 42 obtained in FIG. 7 needs to be changed according to the outside air temperature. There is. In the present embodiment, since the reference value is changed according to FIG. 7, even if the outside air temperature fluctuates, it can be accurately determined that the amount of the refrigerant is insufficient with respect to the appropriate amount.

When the calculation of the liquid level height H2 when the amount of the refrigerant is appropriate is completed in step S5, the control device 100 determines whether or not the current liquid level height H1 is lower than the liquid level height H2 in step S6. do.

When H1 <H2 (YES in step S6), the control device 100 determines that the refrigerant is insufficient in step S7, and outputs an alarm in step S8. The alarm is given, for example, by turning on a lamp or an LED (Light Emitting Diode), or by indicating on the liquid crystal display that the refrigerant is insufficient. As described above, in the first embodiment, the control device 100 is derived from the temperature T1 detected by the temperature sensor 73, the pressure LP detected by the first pressure sensor 90, and the pressure HP detected by the second pressure sensor 92. When the first liquid level height H1 is lower than the second liquid level height H2 corresponding to the pressure detected by the second pressure sensor 92, it is determined that the filling amount of the non-coborous mixed refrigerant is insufficient. do.

On the other hand, when H1 ≧ H2 (NO in step S6), the control device 100 does not perform the processing of steps S7 and S8, but returns the processing to the main routine in step S9.

In step S6 of FIG. 5, the magnitudes of the liquid level height H1 and the liquid level height H2 are simply compared, but if the difference between the liquid level height H1 and the liquid level height H2 is calculated, the difference is large. It is also possible to notify the amount of refrigerant shortage. In this case, the control device 100 has a first liquid level height H1 derived from the temperature T1 detected by the temperature sensor 73, the pressure LP detected by the first pressure sensor 90, and the pressure HP detected by the second pressure sensor 92. And, based on the difference from the second liquid level height H2 corresponding to the pressure HP detected by the second pressure sensor 92, the insufficient amount of the filling amount of the non-coborous mixed refrigerant is determined. Specifically, assuming that ΔH = H2-H1, a map showing the relationship between ΔH and the amount of refrigerant shortage is created in advance, ΔH is calculated in step S6, the shortage amount corresponding to ΔH is read from the map, and the step is taken. In S8, the shortage amount may be notified to the user in place of the alarm or together with the alarm. The shortage amount may be expressed numerically, or may be expressed stepwise by the number of times the LED blinks, the color, or the like.

<Detailed structure of bypass piping>
Since various modifications can be considered in the configuration of the suction end portion of the bypass pipe 86 inserted into the receiver 42, some of them will be described here.

FIG. 9 is a diagram showing the configuration of the first example of the suction end portion of the bypass pipe. In the first example, as shown in FIG. 9, a plurality of openings D1 to D5 are provided at the end of the bypass pipe 86. The openings D1 to D5 are arranged along the flow direction in which the refrigerant is sucked at equal intervals L. Although the opening D5 is provided at the closed end of the bypass pipe, the end may be completely closed and provided on the side surface of the pipe in the same manner as the openings D1 to D4.

FIG. 10 is a diagram for explaining a change in the total area of the opening for sucking gas when the liquid level of the refrigerant in the receiver changes in the first example. FIG. 10 shows the total area ratio of the openings located in the gas portion above the liquid level in the openings D1 to D5 when the total area of the openings D1 to D5 is 1.

When the liquid level closes the opening D1, the area ratio is zero. When the liquid level is located between the openings D1 and the opening D2, the area ratio is 0.6. When the liquid level is located between the openings D2 and D3, the area ratio is 0.76. When the liquid level is located between the openings D3 and D4, the area ratio is 0.88. When the liquid level is located between the openings D4 and D5, the area ratio is 0.95. When the liquid level is located below the opening D5, the area ratio is 1.0.

The sizes of the openings D1 to D5 are determined so that the total area of the openings located in the gas portion changes in this way. The reason why the sizes of the openings D1 to D5 are determined in this way will be described below.

FIG. 11 is a graph showing the degree of dryness corresponding to the change in the area of the hole of the gas portion in the first example. In FIG. 11, the horizontal axis shows the total area ratio of the openings located in the gas portion, and the vertical axis shows the dryness at the inlet of the second expansion device 71 of the refrigerant sucked from the bypass pipe 86. FIG. 12 is a graph showing the relationship between the dryness of the inlet of the bypass pipe and the outlet temperature of the bypass pipe in the first example.

As shown in FIG. 12, the inlet dryness and the outlet temperature (temperature T1) of the second expansion device 71 have a substantially linear relationship. On the other hand, as shown in FIG. 11, the inlet dryness with respect to the total opening area of the gas portion shows a shape like a quadratic curve and is not a straight line. Therefore, assuming that the openings D1 to D5 have the same size, the dryness of the inlet does not change much when the total area ratio of the openings is small, and the amount of change increases as the total area ratio of the openings approaches 1. This makes it difficult to use as a device for detecting the amount of refrigerant because the amount of change in dryness and the amount of change in temperature T1 change depending on the position of the liquid level.

Therefore, as shown on the vertical axis of FIG. 11, the inlet dryness is divided into five equal parts, and the areas of the openings D1 to D5 are determined so as to have the total cross-sectional area ratio of the openings corresponding to each dryness. By doing so, the change in temperature T1 can be made to linearly represent the change in the height of the liquid level, which is convenient for detecting the refrigerant shortage.

FIG. 13 is a diagram showing the configuration of the second example of the suction end portion of the bypass pipe. As shown in FIG. 13, a slit whose height direction is the longitudinal direction may be provided on the side surface of the end portion of the bypass pipe 86. As for the slit, as shown in FIG. 11, when the width of the slit is changed according to the position in the height direction so that the dryness with respect to the total opening area of the gas portion changes in a quadratic curve, the change in temperature T1 is linear. It can be made to represent the change in the height of the liquid level.

FIG. 14 is a diagram showing the configuration of the third example of the suction end portion of the bypass pipe. As shown in FIG. 14, a plurality of pipes having different heights of the suction ports may be provided. Even when a plurality of pipes are provided, as shown in FIG. 11, when the diameter of the pipes is changed according to the position of the opening end in the height direction so that the dryness with respect to the total opening area of the gas part changes in a quadratic curve, the temperature is increased. The change in T1 can be made to linearly represent the change in the height of the liquid level.

FIG. 15 is a diagram showing a configuration of a fourth example in which the end of the bypass pipe is inserted into the receiver from below. FIG. 16 is a diagram showing a configuration of a suction end portion of the bypass pipe of the fourth example. In the fourth example, as in the first example, as shown in FIG. 16, a plurality of openings D1 to D5 are provided at the end of the bypass pipe 86. The openings D1 to D5 are arranged along the flow direction in which the refrigerant is sucked at equal intervals L. The opening D1 is provided on the tip side (upper side), and the opening D5 is provided on the lower side.

FIG. 17 is a diagram for explaining a change in the total area of the opening for sucking gas when the liquid level of the refrigerant in the receiver changes in the fourth example. Assuming that the total area of the openings D1 to D5 is 1, the area ratio of the openings D1 to D5 located in the gas portion above the liquid surface is described.

When the liquid level closes the opening D1, the area ratio is zero. When the liquid level is located between the openings D1 and the opening D2, the area ratio is 0.6. When the liquid level is located between the openings D2 and D3, the area ratio is 0.76. When the liquid level is located between the openings D3 and D4, the area ratio is 0.88. When the liquid level is located between the openings D4 and D5, the area ratio is 0.95. When the liquid level is located below the opening D5, the area ratio is 1.0.

The sizes of the openings D1 to D5 are determined so that the total area of the openings located in the gas portion changes in this way.

FIG. 18 is a graph showing the degree of dryness corresponding to the change in the area of the hole of the gas portion in the fourth example. In FIG. 18, the horizontal axis shows the total area ratio of the openings located in the gas portion, and the vertical axis shows the dryness at the entrance of the second expansion device 71 of the refrigerant sucked from the bypass pipe 86.

As already shown in FIG. 12, the inlet dryness of the second expansion device 71 and the temperature T1 have a substantially linear relationship. Therefore, as shown on the vertical axis of FIG. 18, the inlet dryness is divided into five equal parts, and the areas of the openings D1 to D5 are determined so as to have the total cross-sectional area ratio of the openings corresponding to each dryness.

By doing so, the change in temperature T1 can be made to linearly represent the change in the height of the liquid level, which is convenient for detecting the refrigerant shortage.

Regarding the configuration in which the bypass pipe 86 is inserted from below the receiver 42 as shown in the fourth example, a slit may be provided on the side surface as in the second example, or a plurality of suction port heights may be provided as in the third example. Branch pipes with different sizes may be provided.

The first embodiment will be summarized again with reference to FIG. 1 and the like. The refrigeration cycle device 1 includes a compressor 10, a condenser 20 which is a first heat exchanger, a receiver 42, a first expansion device 50, an evaporator 60 which is a second heat exchanger, and pipes 80 to 84. And a second expansion device 71 provided in the bypass pipe 85. The pipes 80 to 84 constitute a refrigerant circuit 110 that circulates the non-azeotropic mixed refrigerant in the order of the compressor 10, the first heat exchanger, the receiver 42, the first expansion device 50, and the second heat exchanger. The bypass pipe 85 sends the non-azeotropic mixed refrigerant from the receiver 42 to the suction port of the compressor 10 without passing through the first expansion device 50 and the second heat exchanger. A refrigerant inlet D is provided at the end of the bypass pipe 85 inserted into the receiver 42. The refrigerant inlet D is configured so that the opening area for sucking the non-azeotropic mixed refrigerant in the gas state changes when the liquid level height of the receiver 42 changes.

Preferably, the refrigerant inlet D is configured such that when the liquid level height of the receiver 42 changes, the opening area changes within a range of zero or more and the cross-sectional area of the bypass pipe or less.

By providing the refrigerant inlet having such a configuration, the dryness of the refrigerant flowing through the bypass pipe 85 changes when the liquid level height changes. Therefore, the liquid level height H1 can be obtained from the dryness Q based on the relationship shown in FIG. 7.

More preferably, as shown in FIGS. 2, 6, 9, and 10, the end of the bypass pipe 85 inserted into the receiver 42 serves as a refrigerant inlet in the direction of change in the liquid level of the receiver 42. A plurality of openings D1 to D5 provided at different positions are provided.

More preferably, as shown in FIG. 13, a slit S having a change direction of the liquid level of the receiver 42 in the longitudinal direction is provided as a refrigerant inlet at the end inserted into the receiver 42 of the bypass pipe 85. Be done.

Preferably, the refrigeration cycle device 1 has a temperature sensor 73 that detects the temperature T1 of the non-coborous mixed refrigerant that has passed through the second expansion device 71, and the pressure of the non-coborous mixed refrigerant after passing through the second expansion device 71. The first pressure sensor 90 that detects LP, the second pressure sensor 92 that detects the pressure HP of the non-coborous mixed refrigerant before passing through the second expansion device 71, and the temperature T1 and the first that are detected by the temperature sensor 72. A control device 100 for determining the appropriateness of the filling amount of the non-cobo-boiling mixed refrigerant based on the pressure LP detected by the pressure sensor 90 and the pressure HP detected by the second pressure sensor 92 is further provided.

As described above, in the refrigerating cycle apparatus of the first embodiment, when the non-azeotropic refrigerant is used, it is possible to accurately detect that the amount of the refrigerant is less than the appropriate amount regardless of the outside air temperature. can. Therefore, it is possible to detect the refrigerant shortage at an early stage.

Embodiment 2.
The method for detecting a refrigerant shortage described in the first embodiment utilizes the fact that the non-azeotropic refrigerant has a temperature gradient in a two-phase state. Therefore, it is premised that the outlet of the second expansion device 71 is in a two-phase state. However, when the dryness of the inlet of the second expansion device 71 approaches 1, the refrigerant at the outlet of the second expansion device 71 may be in a gas state. In the second embodiment, the refrigerating cycle apparatus capable of detecting the refrigerant shortage will be described including this case. Since the main configuration of the refrigeration cycle device is as shown in FIG. 1, the description will not be repeated.

FIG. 19 is a flowchart for explaining the processing of the refrigerant shortage detection of the second embodiment. The process of this flowchart is repeatedly called from the main routine of control of the refrigeration cycle apparatus to check the amount of refrigerant.

With reference to FIG. 19, when the refrigerant shortage detection process is started, it is determined in step S11 whether or not the superheat degree SH of the refrigerant at the point B is larger than zero. If it is determined in step S11 that SH> 0, the process proceeds to step S15, and the control device 100 determines that the refrigerant is insufficient and outputs a warning in step S16.

FIG. 20 is a ph diagram for explaining the degree of superheat SH. When the pressure is reduced by the second expansion device 71 via the bypass pipe 85 in the path connecting the points A and B shown in FIG. 20, the point B is located between the saturated liquid line LL and the saturated steam line LG. Therefore, the refrigerant is in a two-phase state, and the refrigerant shortage can be detected by the method described in the first embodiment.

On the other hand, when the pressure is reduced by the second expansion device 71 via the bypass pipe in the path connecting the points A'and B'shown in FIG. 20, the point B'is in the gas region to the left of the saturated steam line LG. Since it is located, the refrigerant is in a gas state, and the method described in the first embodiment cannot detect the shortage of the refrigerant.

However, when SH> 0 at the point B', it can be determined that the amount of the station refrigerant sucked from the receiver 42 is small in the first place, so that the refrigerant is insufficient without performing the detection method of the first embodiment. Can be judged.

In step S11 of FIG. 19, it is possible to determine whether SH> 0 or not based on the pressure LP and the temperature T1. A map showing the relationship between the pressure LP and the saturated gas temperature Ts is prepared in advance. First, the saturated gas temperature Ts corresponding to the pressure LP is obtained from the map. If the temperature T1 is higher than the saturated gas temperature Ts, SH> 0, and if the temperature T1 is equal to or lower than the saturated gas temperature Ts, it can be determined that the refrigerant is not in an overheated state.

If SH> 0 is not satisfied in step S11, the liquid level height H1 is calculated in step S12, and the process of comparing the liquid level height H1 and the appropriate height H2 is executed in step S13. Since the details of the processes of steps S12 and S13 are described in steps S1 to S5 of FIG. 5, the description is not repeated here.

When H1> H2 in step S13 (YES in S13), it is determined in step S14 that the amount of the refrigerant is appropriate, and the process is returned to the main routine. On the other hand, if H1> H2 is not satisfied in step S13 (NO in S13), it is determined in step S13 that the refrigerant is insufficient, and an alarm is output in step S16.

As described above, also in the second embodiment, as in the first embodiment, the control device 100 has the temperature T1 detected by the temperature sensor 73, the pressure LP detected by the first pressure sensor 90, and the second pressure. A non-coborous mixed refrigerant when the first liquid level height H1 derived from the pressure HP detected by the sensor 92 is lower than the second liquid level height H2 corresponding to the pressure detected by the second pressure sensor 92. It is judged that the encapsulation amount of is insufficient. Prior to this, in the second embodiment, the control device 100 determines the degree of superheat SH of the non-azeotropic mixed refrigerant determined based on the temperature T1 detected by the temperature sensor 73 and the pressure LP detected by the first pressure sensor 90. Based on this, the insufficient filling amount of the non-azeotropic mixed refrigerant is determined. Therefore, the refrigerating cycle apparatus of the second embodiment has the same effect as the refrigerating cycle apparatus of the first embodiment, and the refrigerant in the bypass pipe is almost in a gas state, but the refrigerant is insufficient. Can be detected.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the description of the embodiment described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Refrigerating cycle device, 2 outdoor unit, 3 indoor unit, 10 compressor, 20 condenser, 22,62 fan, 42 receiver, 50,71 expander, 60 evaporator, 73 temperature sensor, 80,81,82,83 , 84,85 piping, 86,87 bypass piping, 90,92 pressure sensor, 100 controller, 104 memory, 110 refrigerant circuit.

Claims (7)

A refrigeration cycle device that uses a non-azeotropic mixed refrigerant.
With a compressor,
With the first heat exchanger,
With the receiver
With the first expansion device,
With the second heat exchanger,
A refrigerant circuit that circulates the non-azeotropic mixed refrigerant in the order of the compressor, the first heat exchanger, the receiver, the first expansion device, and the second heat exchanger.
A bypass pipe that sends the non-azeotropic mixed refrigerant from the receiver to the suction port of the compressor without going through the first expansion device and the second heat exchanger.
A second expansion device provided in the bypass pipe is provided.
A refrigerant inlet into which the non-azeotropic mixed refrigerant flows is provided at the end of the bypass pipe inserted into the receiver.
The opening area of the refrigerant inlet is configured so that the amount of the non-azeotropic mixed refrigerant in the gas state flowing into the refrigerant inlet changes as the liquid level height of the receiver changes .
The refrigeration cycle device is
A temperature sensor that detects the temperature of the non-azeotropic mixed refrigerant that has passed through the second expansion device, and
A first pressure sensor that detects the pressure of the non-azeotropic mixed refrigerant after passing through the second expansion device, and
A second pressure sensor that detects the pressure of the non-azeotropic mixed refrigerant before passing through the second expansion device, and
Based on the temperature detected by the temperature sensor, the pressure detected by the first pressure sensor, and the pressure detected by the second pressure sensor, a control device for determining the appropriateness of the filling amount of the non-coborous mixed refrigerant. Further prepare
The control device includes a temperature detected by the temperature sensor, a pressure detected by the first pressure sensor, a first liquid level height derived from the pressure detected by the second pressure sensor, and the second pressure sensor. A refrigeration cycle device for determining the appropriateness of the filling amount of the non-coborous mixed refrigerant based on the second liquid level corresponding to the detected pressure. The refrigerating cycle apparatus according to claim 1, wherein the refrigerant inlet is configured such that when the liquid level of the receiver changes, the opening area changes within a range of zero or more and the cross-sectional area of the bypass pipe or less. The second aspect of the present invention, wherein the end of the bypass pipe inserted into the receiver is provided with a plurality of openings provided at different positions in the change direction of the liquid level of the receiver as the refrigerant inlet. Refrigeration cycle equipment. The refrigerating cycle apparatus according to claim 2, wherein a slit having a change direction of the liquid level of the receiver in the longitudinal direction is provided at an end of the bypass pipe inserted into the receiver as the refrigerant inlet. .. The control device, the first liquid level height is, if the second is lower than the liquid level, it is determined that the amount of the enclosed non-azeotropic mixed refrigerant is insufficient, according to claim 1 Refrigeration cycle device. The control device determines the insufficient filling amount of the non-azeotropic mixed refrigerant from the first liquid level height and the second liquid level height, and the temperature detected by the temperature sensor, the first. 1. The refrigerating cycle apparatus according to claim 5 , wherein the insufficient amount of the non-azeotropic mixed refrigerant is determined based on the degree of superheating of the non-azeotropic mixed refrigerant determined based on the pressure detected by the pressure sensor. The control device, the first and the liquid level height, the second liquid level based on the difference between the height, to determine the shortage of the amount of the enclosed non-azeotropic mixed refrigerant, the refrigeration cycle according to claim 1 Device.

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