JP2010078164A - Refrigeration and air conditioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration and air conditioning device capable of continuing a heating/cooling operation without causing shortage of lubricant in each compressor. <P>SOLUTION: The compressor 1, a four-way valve 2, an indoor heat exchanger 3, a first expansion valve 4, and an outdoor heat exchanger 5 are successively connected, and the compressor 1 is constituted as a multistage compressor by connecting a first compressor 1a, a second compressor 1b and a third compressor 1c in series. The first compressor 1a includes a first bypass passage 14 having a third solenoid opening/closing valve 17 in parallel therewith, the second compressor 1b includes a second bypass passage 15 having a forth solenoid opening/closing valve 18 in parallel therewith, and connected with the first bypass passage 14, and the third compressor 1c includes a third bypass passage 16 having a fifth solenoid opening/closing valve 19 in parallel therewith and connected with the second bypass passage 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multi-stage compressor and a refrigerating and air-conditioning apparatus provided with an injection circuit for injecting an intermediate pressure refrigerant into the multi-stage compressor.

  For example, as shown in FIG. 4, the conventional refrigeration air conditioner connects a low-stage compressor 40a and a high-stage compressor 40b in series, an outdoor heat exchanger 41, an intercooler 42, One electromagnetic on-off valve 43, a first expansion valve 44, and an indoor heat exchanger 45 are sequentially connected, and between the intermediate cooler 42, the low-stage compressor 40a, and the high-stage compressor 40b. The injection pipe 46 is connected, branches from between the outdoor heat exchanger 41 and the intermediate cooler 42, and is connected to the bypass passage 47 connected to the intermediate cooler 42 with a second electromagnetic on-off valve 48 and a second An expansion valve 49 is provided. Further, the low-stage compressor 40a is provided with a bypass passage 50 provided with a check valve 51 in parallel therewith, and the high-stage compressor 40b is provided with a bypass provided with a check valve 53 in parallel therewith. A path 52 is provided.

  The high-temperature and high-pressure refrigerant compressed by the low-stage compressor 40a and the high-stage compressor 40b flows into the outdoor heat exchanger 41, releases heat, and condenses. The condensed refrigerant is cooled by the intermediate cooler 42 and then depressurized by the first expansion valve 44, and flows into the indoor heat exchanger 45 to absorb heat and evaporate. The evaporated refrigerant is the low-stage compressor 40a. To reflux. The refrigerant cooled by the intermediate cooler 42 joins the high-temperature refrigerant compressed by the low-stage compressor 40a via the injection pipe 46 and is compressed by the high-stage compressor 40b, and then the outdoor heat A part of the refrigerant condensed by the exchanger 41 is decompressed by the second expansion valve 49 of the bypass passage 47 and cooled to the supercooled state by the intermediate cooler 42. As a result, the object to be cooled can be cooled to an extremely low temperature.

  When the object to be cooled is to be cooled in a relatively high temperature range, if the low-stage compressor 40a and the high-stage compressor 40b are simultaneously operated, the refrigerant circulation amount to the high-stage compressor 40b Therefore, the load on the high-stage compressor 40b is increased, and there is a possibility that trouble may occur in the component parts. In such a case, the check valve 53 of the bypass passage 52 is opened, and the refrigerant flows through the bypass passage 52 to bypass the high-stage compressor 40b. Similarly, when the check valve 51 of the bypass passage 50 is opened, the refrigerant flows around the low-stage compressor 40a.

However, when the low-stage compressor 40a and the high-stage compressor 40b are operated simultaneously, or when either the low-stage compressor 40a or the high-stage compressor 40b is operated, the inside of the compressor Lubricating oil that lubricates these components flows out into the refrigerant circuit, and there is a risk that problems such as seizure may occur in bearings or the like as the components. In order to prevent this, it is necessary to stop the air-conditioning operation and perform the recovery operation of the lubricating oil, and a response has been demanded.
JP-A-4-76357 (2 pages, FIG. 1)

In view of the above problems, an object of the present invention is to provide a refrigerating and air-conditioning apparatus in which each compressor can continue a cooling / heating operation without causing a shortage of lubricating oil.

  The present invention includes a compression mechanism in which a first compression means, a second compression means, and a third compression means are connected in series, a four-way valve, a use side heat exchanger, a first pressure reduction means, and a heat source side heat. The first and second compression means, the third compression means and the third compression means are each provided in parallel with a bypass path provided with an opening / closing means. Yes.

  Further, the suction side of the second compression means, and the use side heat exchanger and the first pressure reduction means are connected by a first injection pipe provided with a second pressure reduction means, and the first compression means The suction side and the second pressure reducing means and the suction side of the second compression means are connected by a second injection pipe provided with a third pressure reducing means.

  According to the first aspect of the present invention, a plurality of compressors are provided with bypass passages provided with opening / closing means in parallel with each of the compressors, and the bypass passages are switched as appropriate to cause a shortage of lubricating oil in the compressors. The air-conditioning operation can be continued. Moreover, the operation | movement which improved energy efficiency can be performed now by selecting and operating a compressor suitably.

  According to invention of Claim 2, injection piping consists of 1st injection piping provided with the 2nd pressure reduction means, and 2nd injection piping which branched from the downstream of the 2nd pressure reduction means and was equipped with the 3rd pressure reduction means. As a result, the injection refrigerant adjusted to an appropriate pressure is supplied to each of the compression means connected in series, and without increasing the discharge temperature from the compression mechanism, the amount of refrigerant discharged from the compression mechanism Can be increased. Further, the refrigerant is injected from the first injection pipe and the second injection pipe branched from the first injection pipe, so that only one of the suction port of the compressor 1a or the suction port of the compressor 1b is injected. Compared with the case where the temperature is increased, the temperature rise of the discharged refrigerant can be further suppressed, while the amount of discharged refrigerant can be increased, and the refrigerant injected to the low pressure side is branched from the high pressure side. The third expansion valve can be downsized by reducing the pressure of the refrigerant decompressed by the second expansion valve with the third expansion valve.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings.

  FIG. 1 is a refrigerant circuit diagram showing a first embodiment of a refrigerating and air-conditioning apparatus according to the present invention, FIG. 2 is a Ph diagram thereof, and FIG. 3 is a refrigerant circuit diagram showing a second embodiment.

  As shown in FIG. 1A, a first embodiment of a refrigeration air conditioner according to the present invention includes a multistage compressor 1 as a compression mechanism, a four-way valve 2 for switching between cooling operation and heating operation, and use side heat. An indoor heat exchanger 3 as an exchanger, a first expansion valve 4 as a pressure reducing means, and an outdoor heat exchanger 5 as a heat source side heat exchanger are sequentially connected to constitute a refrigerant circuit.

  A multistage compressor 1 as a compression mechanism is configured by connecting a first compressor 1a, a second compressor 1b, and a third compressor 1c as compression means in series, and a discharge side of the first compressor 1a. The suction side of the second compressor 1b is connected by a connecting pipe 1d, and the discharge side of the second compressor 1b and the suction side of the third compressor 1c are connected by a connecting pipe 1e, respectively. The refrigerant compressed by the first compressor 1a is caused to flow into the second compressor 1b through the connecting pipe 1d and compressed, and further through the connecting pipe 1e into the third compressor 1c to be compressed to a higher pressure. Therefore, it is possible to obtain the necessary compression differential pressure without using a single-stage compressor having a large compression differential pressure, and thus it is possible to operate corresponding to a wide outside air temperature range. The refrigerant can be compressed without increasing the discharge temperature, and the heating capacity and the cooling capacity can be improved. In this embodiment, the first compressor 1a, the second compressor 1b and the third compressor 1c are described as the compression means of the compression mechanism. However, the compression means is limited to this. Instead, the first compression chamber, the second compression chamber, and the third compression chamber may be included in a single compressor. Moreover, you may combine the compressor from which capability differs as needed.

  From between the indoor heat exchanger 3 and the first expansion valve 4, a heating injection pipe 6 having a first electromagnetic on-off valve 12 is branched, and from between the first expansion valve 4 and the outdoor heat exchanger 5. Is branched by a cooling injection pipe 7 provided with a second electromagnetic on-off valve 13, which joins to a connecting pipe 1e connecting the second compressor 1b and the third compressor 1c. It is connected to a first injection pipe 8 provided with an expansion valve 10. A second expansion valve 11 is connected to a connecting pipe 1d connecting the first compressor 1a and the second compressor 1b from the downstream side of the second expansion valve 10 of the first injection pipe 8. The injection pipe 9 is branched.

  Moreover, a bypass path is added to the multistage compressor 1 to enable individual operation of each compressor. The first compressor 1a is provided with a first bypass passage 14 provided with a third electromagnetic on-off valve 17 in parallel therewith, and the second compressor 1b is provided with a fourth electromagnetic on-off valve 18 in parallel therewith. The second bypass passage 15 connected to the first bypass passage 14 is provided, and the third compressor 1c is provided with a fifth electromagnetic on-off valve 19 in parallel therewith and connected to the second bypass passage 15. A third bypass 16 is provided. Further, the maximum compression capacity is different from the first compressor 1a to the third compressor 1c.

  Next, the flow of the refrigerant during the heating operation will be described. The first compressor 1a, the second compressor 1b, and the third compressor 1c are all operated, and as shown in FIG. 1B, the first electromagnetic on-off valve 12 is opened, but the second electromagnetic The on-off valve 13 is closed.

  The high-temperature and high-pressure refrigerant discharged from the multistage compressor 1 flows into the indoor heat exchanger 3 through the four-way valve 2 as indicated by solid arrows, and the indoor heat exchanger 3 Heat exchanges to release heat and condense. The air heated by the released heat is sent out by a blower fan (not shown) to heat the room. The refrigerant condensed in the indoor heat exchanger 3 is subsequently depressurized by the first expansion valve 4 to become a low temperature and low pressure, flows into the outdoor heat exchanger 5, absorbs ambient heat and evaporates, and the evaporated refrigerant is a multistage compressor. 1 to reflux.

  Further, a part of the refrigerant flowing out of the indoor heat exchanger 3 flows into the heating injection pipe 6 due to the opening of the first electromagnetic on-off valve 12, and is depressurized by the second expansion valve 10 to lower the temperature. After that, the first injection pipe 8 is injected into the connecting pipe 1e. Further, a part of the refrigerant depressurized by the second expansion valve 10 branches to the second injection pipe 9, is further depressurized by the third expansion valve 11, becomes low temperature, and is injected into the connecting pipe 1d. Yes. The refrigerant injected into the connecting pipe 1e merges with the refrigerant discharged from the second compressor 1b, and the refrigerant injected into the connecting pipe 1d merges with the refrigerant discharged from the first compressor 1a, respectively. The refrigerant temperature is lowered by mixing, and after being compressed by the compressor of the next stage, the refrigerant discharged from the second compressor 1b and the third compressor 1c can be increased by being discharged. It has become. As a result, the amount of refrigerant discharged can be increased while preventing an increase in the temperature of the refrigerant discharged from the multistage compressor 1.

  The refrigerant flow during the heating operation described above will be described with reference to the Ph diagram of FIG. The horizontal axis of the Ph diagram is specific enthalpy and the vertical axis is pressure. Further, since a gas-liquid separator is usually used for the injection circuit, the branching point of the second injection pipe 9 from the first injection pipe 8 is not shown in the refrigerant circuit of FIG. It is assumed that a first gas-liquid separator is provided, and a second gas-liquid separator (not shown) is also provided downstream of the third expansion valve 11 of the second injection pipe 9. The liquid refrigerant separated by the second gas-liquid separator is decompressed by an expansion valve (not shown) and connected to the upstream side of the outdoor heat exchanger 5.

  The low-temperature and low-pressure gas refrigerant that has flowed into the first compressor 1a is compressed from the state A to the state B, and then injected into the connecting pipe 1d via the second injection pipe 9 described later, As a result, the temperature drops to state C. The refrigerant whose temperature has been lowered is further compressed by the second compressor 1b and shifted to the state D, and then injected into the connecting pipe 1e via the first injection pipe 8 to be described later, and has a higher pressure than the injection refrigerant in the state N. The refrigerant is mixed with the injection refrigerant in the state P, and the temperature is lowered to the state E so as to be sucked into the third compressor 1c.

  After the refrigerant flows into the third compressor 1c and is further compressed, the refrigerant enters the state F, flows into the indoor heat exchanger 3, releases heat, and condenses to reduce the enthalpy at a constant pressure. The state G is shifted to. The liquid phase refrigerant that has shifted to the state G is depressurized by the first expansion valve 4 to become a low temperature and a low pressure, and then shifts to the state I. The first compressor 1a is refluxed. A part of the refrigerant condensed in the indoor heat exchanger 3 and shifted to the state G flows into the heating injection pipe 6 and is decompressed by the second expansion valve 10 to be in the state H. The gas refrigerant separated into the gas refrigerant and the liquid refrigerant by the liquid separator and separated into the state P is injected into the connecting pipe 1e, and the liquid refrigerant separated into the state J flows into the second injection pipe 9. It is like that.

  The refrigerant flowing into the second injection pipe 9 is decompressed by the third expansion valve 11 as indicated by the solid line J → K, and is separated into gas refrigerant and liquid refrigerant by the second gas-liquid separator. The gas refrigerant separated into the state N is injected into the connecting pipe 1d, and the liquid refrigerant separated into the state L is decompressed to the state M by an expansion valve (not shown), and the first expansion valve 4 and the outdoor heat exchanger 5 are discharged. It merges with the refrigerant flowing between the two.

  The refrigerant is injected into the multistage compressor 1 from the first injection pipe 8 and the second injection pipe 9 branched from the first injection pipe 8, so that the multistage compression is performed as compared with the case where the refrigerant is injected into only one of them. While the temperature rise of the refrigerant discharged from the machine 1 can be further suppressed, the amount of discharged refrigerant can be increased. Further, the third expansion valve 11 can be reduced in size by branching the refrigerant injected to the low pressure side from the high pressure side and reducing the refrigerant decompressed by the second expansion valve 10 by the third expansion valve 11. It is like that.

  In addition, the refrigerant that has been decompressed by the second expansion valve 10 and has become an intermediate pressure is injected by the first injection pipe 8 into the connecting pipe 1e that connects the second compressor 1b and the third compressor 1c, while the second expansion is performed. A part of the refrigerant depressurized by the valve 10 branches to the second injection pipe 9 and is further depressurized by the third expansion valve 11 to become a low pressure, and the connecting pipe 1d connecting the first compressor 1a and the second compressor 1b. Are injected into the multi-stage compressor 1, respectively, so that smooth operation can be performed without causing any trouble in the compression process in the multi-stage compressor 1. It is like that.

  Next, the flow of the refrigerant during the cooling operation will be described. The four-way valve 2 is switched to the dotted line side, and as shown in FIG. 1 (B), the first electromagnetic on-off valve 12 is closed, but the second electromagnetic on-off valve 13 is open.

  The high-temperature and high-pressure refrigerant discharged from the multistage compressor 1 flows into the outdoor heat exchanger 5 through the four-way valve 2 as shown by the broken arrow, and releases heat to condense. The condensed refrigerant is subsequently depressurized by the expansion valve 4 to become a low temperature and a low pressure, evaporates in the indoor heat exchanger 3, and returns to the multistage compressor 1.

  The refrigerant flowing out of the outdoor heat exchanger 5 is first injected through the cooling injection pipe 7 by opening the second electromagnetic switching valve 13 and closing the first electromagnetic switching valve 12. After flowing into the pipe 8 and being depressurized by the second expansion valve 10, it is injected into the connecting pipe 1e. Further, a part of the refrigerant decompressed by the second expansion valve 10 flows into the second injection pipe 9 and further decompressed by the third expansion valve 11 to become a low pressure, and is injected into the connecting pipe 1d. Yes.

  Also in the cooling operation, the refrigerant injected from the first injection pipe 8 and the second injection pipe 9 and the refrigerant compressed by the first compressor 1a and the second compressor 1b merge to form the multistage compressor 1. While the temperature rise of the discharged refrigerant is prevented, the discharged refrigerant amount can be increased.

  As shown in FIG. 3B, when all of the first compressor 1a to the third compressor 1c are operated, the third electromagnetic on-off valve 17, the fourth electromagnetic on-off valve 18, and the fifth electromagnetic on-off valve 19 are all The refrigerant flow in the air conditioning operation is the same as in the first embodiment. By operating all of the first compressor 1a to the third compressor 1c and performing the injection operation, the heating operation is sufficient even in a cold region where the outside air temperature drops to -10 ° C or lower, for example. Heating capacity can be obtained.

  In early spring when the climate is warm, the above-mentioned bypass path is used in combination so that efficient operation can be performed while saving energy consumption. As shown in FIG. 3 (B), when the first compressor 1a on the lowest pressure side is operated and the second compressor 1b and the third compressor 1c are stopped to perform the cooling / heating operation, a third electromagnetic on-off valve is used. 17 is closed, but the fourth electromagnetic on-off valve 18 and the fifth electromagnetic on-off valve 19 are opened. The refrigerant recirculated from the four-way valve 2 to the multistage compressor 1 is compressed by the first compressor 1a, then the second compressor 1b and the third compressor 1c are stopped, and the fourth electromagnetic on-off valve 18 and the second Since the five electromagnetic on-off valves 19 are opened, the multistage compressor 1 is discharged through the second bypass passage 15 and the third bypass passage 16. The first electromagnetic on-off valve 12 and the second electromagnetic on-off valve 13 are closed so that the injection operation is not performed. As a result, heating operation or cooling operation with minimum energy consumption can be performed according to the climate.

  Furthermore, when operating the 2nd compressor 1b and stopping the 1st compressor 1a and the 3rd compressor 1c, as shown to FIG. 3 (B), the 3rd electromagnetic on-off valve 17 and the 5th electromagnetic on-off valve 19 is opened, but the fourth electromagnetic on-off valve 18 is closed. The refrigerant recirculated from the four-way valve 2 to the multistage compressor 1 is stopped by the first compressor 1a and the third electromagnetic on-off valve 17 is opened, whereby the second compressor 1b is passed through the first bypass passage 14. The third compressor 1c is stopped and the fifth electromagnetic on-off valve 19 is opened, so that the multi-stage compressor 1 is discharged through the third bypass 16 after being compressed. ing. Similarly, when operating only the third compressor 1c on the highest pressure side, the third electromagnetic on-off valve 17 and the fourth electromagnetic on-off valve 18 are opened, but the fifth electromagnetic on-off valve 19 is closed. Thus, the refrigerant recirculated from the four-way valve 2 to the multistage compressor 1 is discharged after being compressed by the third compressor 1c via the first bypass passage 14 and the second bypass passage 15. ing. In addition, the 1st compressor 1a and the 2nd compressor 1b are compressors from which compression ratio differs, respectively, By operating these individually, the most energy efficient operation | movement can be selected according to external temperature. You may do it.

  In addition, two arbitrary compressors can be operated. As shown in FIG. 1B, when the first compressor 1a and the second compressor 1b are operated and the third compressor 1c is stopped, the third electromagnetic on-off valve 17 and the fourth electromagnetic on-off valve 18 are Although it is closed, the fifth electromagnetic opening / closing valve 19 is opened. The refrigerant recirculated from the four-way valve 2 to the multistage compressor 1 is compressed by the first compressor 1a and the second compressor 1b, and then the third compressor 1c is stopped and the fourth electromagnetic on-off valve 18 is opened. As a result, the multistage compressor 1 is discharged through the third bypass 16.

  When the second compressor 1b and the third compressor 1c are operated and the first compressor 1a is stopped, the third electromagnetic open / close valve 17 is opened, but the fourth electromagnetic open / close valve 18 and the fifth electromagnetic open / close valve are opened. The valve 19 is closed. The refrigerant recirculated from the four-way valve 2 to the multistage compressor 1 is stopped by the first compressor 1a and the third electromagnetic on-off valve 17 is opened, whereby the second compressor 1b is connected via the first bypass passage 14. , And compressed by the second compressor 1b, and then compressed by the third compressor 1c to become a high temperature and high pressure and discharged from the multistage compressor 1. In addition, when the first compressor 1a and the third compressor 1c are operated and the second compressor 1b is stopped, the fourth electromagnetic on / off valve 18 is opened, but the third electromagnetic on / off valve 17 and the fifth electromagnetic on / off valve are opened. The on-off valve 19 is closed. The refrigerant recirculated from the four-way valve 2 to the multistage compressor 1 is compressed by the first compressor 1a, then the second compressor 1b is stopped, and the fourth electromagnetic on-off valve 18 is opened, so that the second The refrigerant flows into the third compressor 1 c via the bypass 15, is compressed, becomes a high temperature and a high pressure, and is discharged from the multistage compressor 1.

  As described above, the operation state of the first compressor 1a, the second compressor 1b, and the third compressor 1c is operated and stopped according to the outside air temperature state or the indoor temperature state, and correspondingly By opening and closing the flow paths of the first bypass path 14, the second bypass path 15, and the third bypass path 16, the output of the multistage compressor can be varied in various ways from the minimum output to the maximum output, thereby heating In operation, it is possible to perform an operation with an improved coefficient of performance (COP) while improving energy consumption efficiency from extremely cold to relatively warm seasons.

  Next, the lubricating oil retention effect in each compressor will be described. In the first compressor 1a, the second compressor 1b, and the third compressor 1c, lubricating oil is stored inside, and the stored lubricating oil is appropriately supplied to a sliding portion and a driving mechanism inside the compressor. ing. However, when the refrigerant is compressed and discharged from each compressor, a small amount of lubricating oil flows out into the refrigerant circuit in a state of being contained in the refrigerant, and if the lubricating oil is sufficiently returned, the lubricating oil is insufficient. It will be. When the lubricating oil shortage occurs, seizure or the like occurs on the sliding portion, resulting in trouble in operation.

  When the first compressor 1a and the second compressor 1b are operated and the third compressor 1c is stopped, the lubricant is mixed with refrigerant from the first compressor 1a and the second compressor 1b, and the lubricating oil is supplied to the refrigerant circuit. In this case, the third electromagnetic on-off valve 17 is opened while the fourth electromagnetic on-off valve 18 and the fifth electromagnetic on-off valve 19 are closed. Then, by switching to the operation of the second compressor 1b and the third compressor 1c, the lubricating oil is supplied from the refrigerant circuit to the second compressor 1b and the third compressor 1c via the first bypass passage 14. Thus, it is possible to prevent a shortage of lubricating oil in each of these compressors, and when switching to operation with the first compressor 1a, lubrication returns only to the first compressor 1a. Oil can prevent a shortage of lubricating oil. Similarly, by switching various operations as shown in FIG. 1 (B), the cooling / heating operation can be continued while avoiding the occurrence of a lack of lubricating oil in each compressor.

  Further, during the cooling operation, the first compressor 1a is operated alone, and the discharged high-temperature and high-pressure refrigerant is caused to flow into the indoor heat exchanger 3 through the second bypass passage 15 and the third bypass passage 16, The heat dissipation amount of these bypass passages and the heat dissipation amount in the indoor heat exchanger 3 are added, and the amount of evaporation increases in the outdoor heat exchanger 5 by increasing the condensation amount, so that the effect in the cooling operation can be expected. It has become. Further, when the third compressor 1c is operated independently during the heating operation, heat absorption is performed in the first bypass passage 14 and the second bypass passage 15, and the heat absorption amount of the refrigerant flowing into the third compressor 1c is increased. By doing so, the amount of heat radiation in the indoor heat exchanger 3 is increased, and the effect in the heating operation can be expected.

  Next, a second embodiment will be described. In addition, about the structure which is common in 1st Example, the same name and the same number are provided and demonstrated. In the second embodiment, as shown in FIG. 3A, the first compressor 1a, the second compressor 1b, and the third compressor 1c are connected in series, and the first bypass described in the first embodiment is used. A multistage compressor 1 having a path 14, a second bypass path 15, and a third bypass path 16, a four-way valve 2 for switching between cooling and heating operations, an indoor heat exchanger 3, a fourth expansion valve 20, and a fifth The expansion valve 21 and the outdoor heat exchanger 5 are sequentially connected to form a main circuit, and in parallel with the fourth expansion valve 20, a fourth bypass path 22 having a sixth electromagnetic on-off valve 23 is provided, In parallel with the fifth expansion valve 21, a fifth bypass path 24 including a seventh electromagnetic opening / closing valve 25 is provided.

  From between the indoor heat exchanger 3 and the fourth expansion valve 20, a pipe 26 for injection during heating operation, which includes the eighth electromagnetic on-off valve 28 and the third expansion valve 10 in the first embodiment, branches. The pipe 26 is connected to the first injection pipe 8 connected to the connecting pipe 1e connecting the second compressor 1b and the third compressor 1c, and to the first compressor 1a and the second compressor 1b. It is connected to a pipe 1d and branched to a second injection pipe 9 provided with a third expansion valve 11. Further, between the pipe 26, the pipe connecting the fourth expansion valve 20 and the fifth expansion valve 21, and the return pipe 30 returning to the multistage compressor 1 from the four-way valve 2, between the refrigerant flowing through these pipes A multiple saddle type inter-refrigerant heat exchanger 31 for performing heat exchange is provided. In addition, a ninth electromagnetic on-off valve 29 is provided between the fourth expansion valve 20 and the multiple rod-type inter-refrigerant heat exchanger 31 and is connected between the eighth electromagnetic on-off valve 28 and the third expansion valve 10. The piping 27 for injection during cooling operation is branched.

  Next, the flow of the refrigerant during the heating operation will be described. As shown in FIG. 3B, the sixth electromagnetic on-off valve 23 and the eighth electromagnetic on-off valve 28 are in an open state, but the seventh electromagnetic on-off valve 25 and the ninth electromagnetic on-off valve 29 are in a closed state. In addition, the first compressor 1a, the second compressor 1b, and the third compressor 1c constituting the multistage compressor 1 are all operated.

  The high-temperature and high-pressure refrigerant discharged from the multistage compressor 1 flows into the indoor heat exchanger 3 through the four-way valve 2 as shown by the solid arrows, and releases heat in the indoor heat exchanger 3 to condense. To do. The released heat is sent out by a blower fan (not shown) to heat the room. The refrigerant condensed in the indoor heat exchanger 3 is then opened via the fourth bypass path 22 having a low flow path resistance due to the opening of the sixth electromagnetic on-off valve 23. In the process of flowing through the multi-cup type inter-refrigerant heat exchanger 31, heat is exchanged with the low-temperature refrigerant flowing through the pipe 26 and the return pipe 30 to be cooled. The cooled refrigerant passes through the fifth expansion valve 21 when the seventh electromagnetic on-off valve 25 is closed, and is depressurized by the fifth expansion valve 21 to become a low-temperature and low-pressure supercooled refrigerant. The refrigerant flows into the outdoor heat exchanger 5, and the gaseous refrigerant evaporated by absorbing ambient heat in the outdoor heat exchanger 5 is returned to the multistage compressor 1 through the four-way valve 2. It has become.

  In the multiple heat exchanger 31, the refrigerant flowing out of the indoor heat exchanger 3 and flowing into the outdoor heat exchanger 5 through the fifth expansion valve 21 flows into the pipe 26 and is decompressed by the third expansion valve 10 to be cooled at low temperature and low pressure. The heat exchange between the refrigerant thus obtained and the low-temperature and low-pressure refrigerant flowing through the return pipe 30 flowing back to the multistage compressor 1 from the outdoor heat exchanger 5 through the four-way valve 2 allows efficient cooling and supercooling. It can be used as a refrigerant.

  In addition, a part of the condensed refrigerant flowing out of the indoor heat exchanger 3 flows into the pipe 26 due to the opening of the eighth electromagnetic on-off valve 28 and is decompressed by the third expansion valve 10 to become low temperature and low pressure. Thereafter, the refrigerant flowing through the main circuit is cooled by the multi-heated inter-refrigerant heat exchanger 31, so that the temperature rises to become an intermediate pressure refrigerant. It is injected into a connecting pipe 1e that connects the machine 1c. Further, a part of the refrigerant decompressed by the third expansion valve 10 branches to the second injection pipe 9, further decompressed by the fourth expansion valve 11, becomes a lower pressure than the refrigerant flowing through the first injection pipe 8, It is injected into a connecting pipe 1d that connects the first compressor 1a and the second compressor 1b.

  As described in the first embodiment, the amount of high-temperature and high-pressure refrigerant discharged from the multistage compressor 1 is increased by injecting refrigerant from the first injection pipe 8 and the second injection pipe 9 into the multistage compressor 1. As a result, the amount of refrigerant condensed in the indoor heat exchanger 3 is increased, so that the heating capacity is greatly enhanced.

  Next, the flow of the refrigerant during the cooling operation will be described. The four-way valve 2 is switched to the dotted line side, and as shown in FIG. 3B, the seventh electromagnetic on-off valve 25 and the ninth electromagnetic on-off valve 29 are opened, but the sixth electromagnetic on-off valve 23 and the eighth electromagnetic on-off valve The on-off valve 28 is closed.

  The high-temperature and high-pressure refrigerant discharged from the multistage compressor 1 flows into the outdoor heat exchanger 5 through the four-way valve 2 as shown by the broken arrow, and releases heat to condense. The condensed refrigerant passes through the fifth bypass path 24 having a low flow path resistance by opening the seventh electromagnetic on-off valve 25, and is connected to the pipe 26 and the return pipe 30 in the multi-type inter-refrigerant heat exchanger 31. The refrigerant is cooled by exchanging heat with a low-temperature refrigerant flowing through the refrigerant, and the cooled refrigerant is decompressed by the fourth expansion valve 20 and flows into the indoor heat exchanger 3 by closing the sixth electromagnetic on-off valve 23. It has become. The refrigerant in the gas state that has absorbed and evaporated the ambient heat in the indoor heat exchanger 3 is refluxed to the multistage compressor 1 via the four-way valve 2. The cooled air flowing around the indoor heat exchanger 3 is sent out indoors by a blower fan (not shown) to perform a cooling operation.

  In addition, the refrigerant in the main circuit that has flowed out of the multiple saddle-type inter-refrigerant heat exchanger 31 passes through the pipe 27 because the ninth electromagnetic on-off valve 29 is opened and the eighth electromagnetic on-off valve 28 is closed. The refrigerant flows into the pipe 26 and is depressurized by the second expansion valve 10 to become a low temperature and low pressure. One injection pipe 8 is adapted to inject the connecting pipe 1e. Further, a part of the refrigerant decompressed by the third expansion valve 10 flows into the second injection pipe 9 and further decompressed by the fourth expansion valve 11 to become a low pressure, and is injected into the connecting pipe 1d. Yes.

  As described above, in the second embodiment, in the heating operation, the refrigerant flowing through the main circuit is cooled by the multi-heated inter-refrigerant heat exchanger 31 and the refrigerant in the subcooled state is absorbed by the outdoor heat exchanger 5. As a result, the evaporation enthalpy per unit flow rate increases, and the amount of heat absorbed by the outdoor heat exchanger 5 increases. Accordingly, the amount of condensation and the amount of heat release in the indoor heat exchanger 3 are increased, and the heating capacity can be further enhanced. In addition, by performing heat exchange between the refrigerants in a lump using the multi-type inter-refrigerant heat exchanger 31, the refrigerant circuit can be simplified while improving the heat exchange efficiency between the refrigerants. In addition, as described in the first embodiment, by switching a plurality of bypass passages provided in the multistage compressor 1 according to the outside air temperature, an efficient operation that saves energy consumption, The cooling and heating operation can be continued without causing a shortage of lubricating oil.

It is a refrigerant circuit figure in the 1st example of the present invention. It is a Ph diagram in the first embodiment. It is a refrigerant circuit figure in the 2nd example of the present invention. It is a refrigerant circuit diagram provided with the conventional injection circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multistage compressor 1a 1st compressor 1b 2nd compressor 1c 3rd compressor 1d Connection pipe 1e Connection pipe 2 Four-way valve 3 Indoor heat exchanger 4 1st expansion valve 5 Outdoor heat exchanger 6 Heating injection pipe 7 Injection pipe for cooling 8 First injection pipe 9 Second injection pipe 10 Second expansion valve 11 Third expansion valve 12 First electromagnetic on-off valve 13 Second electromagnetic on-off valve 14 First bypass path 15 Second bypass path 16 Third Bypass passage 17 Third electromagnetic on-off valve 18 Fourth electromagnetic on-off valve 19 Fifth electromagnetic on-off valve 20 Fourth expansion valve 21 Fifth expansion valve 22 Fourth bypass passage 23 Sixth electromagnetic on-off valve 24 Fifth bypass passage 25 Seventh electromagnetic On-off valve 26 Piping 27 Piping 28 Eighth electromagnetic on-off valve 29 Ninth electromagnetic on-off valve 30 Return pipe 31 Multi-type refrigerant heat exchanger

Claims (2)

  A compression mechanism in which a first compression means, a second compression means, and a third compression means are connected in series, a four-way valve, a use side heat exchanger, a first pressure reduction means, and a heat source side heat exchanger. A refrigerating and air-conditioning apparatus comprising a bypass path provided with an opening / closing means in parallel with at least the first compression means and the third compression means.   The suction side of the first compression means is connected to the suction side of the second compression means and between the use side heat exchanger and the first pressure reduction means by a first injection pipe provided with a second pressure reduction means. The refrigerating and air-conditioning according to claim 1, wherein the second pressure reducing means and the suction side of the second compressing means are connected by a second injection pipe provided with a third pressure reducing means. apparatus.

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