JP2015169347A - Heat pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump device that enables simultaneous operations as a cooling operation and a heating operation by making good use of a low stage-side compressor and a high stage-side compressor for two-stage compression.SOLUTION: A heat pump device includes: a heat source-side heat exchanger (37); a first use-side heat exchanger (33); a low stage-side compressor (31); a high stage-side compressor (32); and a second use-side heat exchanger (38) provided on a branch circuit (24) branching off from a freezing circuit (21) on a discharge side of the high stage-side compressor (32). In simultaneous operations as a cooling operation by the first use-side heat exchanger (33) and a heating operation by the second use-side heat exchanger (38), part of a refrigerant sent from the first use-side heat exchanger (33) is guided to the high stage-side compressor (32), and a refrigerant compressed by the high stage-side compressor (32) is sent to the second use-side heat exchanger (38) through the branch circuit (24).

Description

  The present invention generally relates to a heat pump device, and more particularly to a two-stage compression heat pump device including a lower stage compressor and a higher stage compressor on a refrigeration circuit constituting a heat pump cycle.

  Regarding a conventional heat pump device, for example, Japanese Patent Laid-Open No. 4-80545 discloses that a single-stage compression operation can be performed when the blowing temperature is low or the outside air temperature is high, thereby realizing a refrigeration cycle with high energy efficiency. A heat pump type air conditioner for the purpose is disclosed (Patent Document 1).

  A heat pump air conditioner disclosed in Patent Document 1 includes a compression device having two compression mechanisms, a first compression unit and a second compression unit, and a control unit that controls switching between single-stage compression operation and two-stage compression operation. Is provided.

  Japanese Laid-Open Patent Publication No. 2001-235246 discloses that the switching mechanism between the single-stage compression operation and the two-stage compression operation is simplified to enable cost reduction and circuit simplification, and at the same time, the switching control is easily performed. An intended refrigeration apparatus is disclosed (Patent Document 2).

  In the refrigeration apparatus disclosed in Patent Document 2, switching between a single-stage compression operation and a two-stage compression operation is performed by a four-way switching valve.

  Japanese Patent Application Laid-Open No. 2001-56157 discloses a refrigeration apparatus that aims to secure a storage amount of refrigeration oil in a high-stage compressor of a two-stage compression refrigeration cycle, avoid troubles, and improve reliability. Is disclosed (Patent Document 3).

  The refrigeration apparatus disclosed in Patent Document 3 gas-liquid separates intermediate pressure refrigerant between a low-stage compressor and a high-stage compressor that perform a two-stage compression refrigeration cycle, and a first expansion valve and a second expansion valve. And a gas-liquid separator, and an injection pipe that connects the gas-liquid separator and a first discharge pipe that connects the low-stage compressor and the high-stage compressor. The internal pipe line of the injection pipe in the gas-liquid separator is formed in a J shape, and an oil hole is formed in the curved lower part. The refrigerating machine oil stored in the gas-liquid separator flows into the injection pipe through the oil hole and is sent to the high stage compressor together with the gas refrigerant.

Japanese Patent Laid-Open No. 4-80545 JP 2001-235246 A JP 2001-56157 A

  As disclosed in the above-mentioned patent document, a two-stage compression heat pump apparatus including a low-stage compressor and a high-stage compressor on a refrigeration circuit constituting a heat pump cycle is known.

  A characteristic of the two-stage compression is that the efficiency is good when the outside air temperature is low, that is, when the compression ratio between the condensation side and the evaporation side is large. However, when the two-stage compression is used when the compression ratio between the condensation side and the evaporation side is not large, the efficiency is reduced as compared with the case where the one-stage compression is used. Therefore, as a means for solving such a problem, a method of switching between one-stage compression and two-stage compression depending on conditions is used.

  In a heat pump device that can switch between one-stage compression and two-stage compression, two-stage compression is used during heating (heating) operation in which the evaporation pressure is low and operation at a high compression ratio is required, while cooling that is in a reverse cycle ( During the cooling) operation or the defrosting operation, the refrigerant temperature corresponding to the refrigerant pressure in the heat source side heat exchanger does not necessarily follow the outside air temperature, and therefore, generally two-stage compression is used rather than one-stage compression. At this time, the high stage compressor is stopped and has no intended use.

  On the other hand, in order to switch between a cooling operation and a heating operation in a heat pump device, it is necessary to stop the operation once and then restart the operation in a reverse cycle. For example, there is a demand for simultaneous cooling and hot water supply in summer, but the cooling operation and the heating operation cannot be performed simultaneously.

  Accordingly, one object of the present invention is to solve the above-mentioned problem, and it is possible to simultaneously perform a cooling operation and a heating operation by utilizing a low-stage compressor and a high-stage compressor for two-stage compression. It is to provide a heat pump device.

  Next, in the two-stage compression heat pump device, there is a problem that the refrigerant suction temperature and the discharge temperature in the high-stage compressor rise and exceed the operating range of the compressor. As means for solving such problems, a pipe line between the low-stage compressor and the high-stage compressor, and a pipe line between the use side heat exchanger (condenser) and the heat source side heat exchanger (evaporator) An injection pipe is provided to connect the two and a part of the refrigerant flowing through the pipe between the use side heat exchanger and the heat source side heat exchanger, and the low stage side compressor and the high stage side compression are passed through the injection pipe. There is a method of injecting into the pipeline between machines. In this case, it is possible to reduce the refrigerant suction temperature in the high-stage compressor and realize operation with reliability.

  On the other hand, in a compressor used in a heat pump apparatus, a compressor mechanism and a bearing are lubricated using refrigerating machine oil stored in the cylinder. However, depending on the amount of refrigerant injected into the pipe line between the low stage side compressor and the high stage side compressor through the injection pipe line, the liquid refrigerant may be excessively supplied to the high stage side compressor. In this case, the refrigerating machine oil in the cylinder of the high stage side compressor is likely to be discharged together with the liquid refrigerant along with the compression process in the high stage side compressor, and the refrigerating machine oil in the cylinder may be rapidly reduced.

  Therefore, another object of the present invention is to solve the above-described problems and to provide a heat pump device that keeps the amount of refrigeration oil in a high-stage compressor appropriately.

  A heat pump device according to one aspect of the present invention is provided on a refrigeration circuit that constitutes a heat pump cycle, and is provided on a heat source side heat exchanger that performs heat exchange between the refrigerant and the heat source, and on the refrigeration circuit. A first use side heat exchanger that exchanges heat between the use fluids, and a refrigerant that is provided on the refrigeration circuit and that is sent from the heat source side heat exchanger during heating operation in the first use side heat exchanger, A low-stage compressor that compresses refrigerant sent from the first use-side heat exchanger during the cooling operation in the first use-side heat exchanger, and a refrigerant that is provided on the refrigeration circuit and that is sent from the low-stage compressor are compressed. A high-stage compressor, and a second usage-side heat exchanger that is provided on a branch circuit that branches from the discharge-side refrigeration circuit of the high-stage compressor and that exchanges heat between the refrigerant and the utilization fluid. . During simultaneous operation of the cooling operation in the first usage-side heat exchanger and the heating operation in the second usage-side heat exchanger, a part of the refrigerant sent from the first usage-side heat exchanger is guided to the high stage compressor. The refrigerant compressed by the high stage side compressor is sent to the second usage side heat exchanger through the branch circuit.

  Preferably, the heat pump device is provided on a refrigeration circuit between the first usage-side heat exchanger and the heat source-side heat exchanger, and a gas-liquid separator that separates the refrigerant into a gas phase and a liquid phase; Provided on a refrigeration circuit between the use side heat exchanger and the gas-liquid separator, provided on the refrigeration circuit between the gas-liquid separator and the heat source side heat exchanger; And a second decompression device for decompressing the refrigerant. The branch circuit is connected to an injection circuit that guides a part of the gas-phase refrigerant separated by the gas-liquid separator to a refrigeration circuit between the low-stage compressor and the high-stage compressor.

  Preferably, the heat pump device further includes a third decompression device that is provided on the branch circuit and decompresses the refrigerant sent from the second usage-side heat exchanger.

Preferably, the third pressure reducing device has a function of blocking a pipe line forming the branch circuit.
Preferably, the branch circuit is connected to a refrigeration circuit on the discharge side of the low stage compressor.

  A heat pump device according to another aspect of the present invention includes a heat source side heat exchanger that exchanges heat between a refrigerant and a heat source, a use side heat exchanger that exchanges heat between the refrigerant and a use fluid, and a heat source. A low-stage compressor that compresses the refrigerant sent from the side heat exchanger, a cylinder that stores refrigeration oil, and a high-stage compressor that compresses the refrigerant sent from the low-stage compressor in the cylinder; A first decompression device for decompressing the refrigerant sent from the use side heat exchanger, a gas-liquid separator for separating the refrigerant sent from the first decompression device into a gas phase and a liquid phase, and a liquid phase side of the gas-liquid separator Is connected to the gas phase side of the gas-liquid separator, and the refrigerant sent from the gas-liquid separator is connected to the low-stage compressor. Injection pipe leading to the pipe line between the compressor and the compressor oil in the cylinder As a predetermined amount of oil above, and a control unit for controlling at least one of the delivery rate of the pressure reduction ratio and the high-stage compressor of the second pressure reducing device.

  Preferably, the heat pump device is provided on a pipe line between the first pressure reducing device and the gas-liquid separator, and includes a first temperature detection unit that detects a refrigerant temperature T1, a low-stage compressor, and a high-stage side. And a second temperature detection unit that is provided on a pipe line between the compressor and that detects a temperature T2 of the refrigerant after the refrigerant flowing through the injection pipe merges. Based on the comparison between the refrigerant temperature T1 detected by the first temperature detection unit and the refrigerant temperature T2 detected by the second temperature detection unit, the control unit determines that the amount of refrigerating machine oil in the cylinder is appropriate. It is determined whether or not there is.

  Preferably, the control unit is configured such that the state in which the refrigerant temperature T2 detected by the second temperature detection unit is equal to the refrigerant temperature T1 detected by the first temperature detection unit continues for a predetermined time. In addition, it is determined that the amount of refrigerating machine oil in the cylinder is not appropriate.

  Preferably, the heat pump device is provided on a pipe line between the first pressure reducing device and the gas-liquid separator, and includes a first temperature detection unit that detects a refrigerant temperature T1, a high-stage compressor, and use-side heat. A third temperature detection unit and a pressure detection unit that are provided on a pipe line to the exchanger and detect the temperature T3 and the pressure P of the refrigerant, respectively. In the p (pressure) -h (specific enthalpy) diagram, the control unit is detected by the intermediate pressure line determined from the refrigerant temperature T1 detected by the first temperature detection unit, the third temperature detection unit, and the pressure detection unit. The specific enthalpy H ′ is specified from the intersection with the isentropic line passing through the point determined from the temperature T3 and the pressure P of the refrigerant, and based on the comparison between the specific enthalpy H ′ and the specific enthalpy H of the saturated vapor on the intermediate pressure line Then, it is determined whether or not the amount of refrigerating machine oil in the cylinder is appropriate.

  Preferably, the heat pump device is a pipe line between the low-stage compressor and the high-stage compressor, and is provided on a pipe through which the refrigerant flows after the refrigerant flowing through the injection pipe flows. A buffer unit for storing the refrigerant is further provided. The buffer unit has a return line for returning the refrigeration oil stored together with the liquid refrigerant to the high stage compressor.

  According to one aspect of the present invention, there is provided a heat pump device that enables simultaneous operation of cooling operation and heating operation using a low-stage compressor and a high-stage compressor for two-stage compression. it can.

  Moreover, according to another situation of this invention, the heat pump apparatus which keeps the oil quantity of the refrigerating machine oil in a high stage side compressor appropriately can be provided.

In the heat pump apparatus in Embodiment 1 of this invention, it is a circuit diagram which shows the refrigerant | coolant flow at the time of a heating operation (two-stage compression). In the heat pump apparatus in Embodiment 1 of this invention, it is a circuit diagram which shows the refrigerant | coolant flow at the time of heating operation (1 step | paragraph compression). In the heat pump apparatus in Embodiment 1 of this invention, it is a circuit diagram which shows the refrigerant | coolant flow at the time of cooling operation. In the heat pump apparatus in Embodiment 1 of this invention, it is a circuit diagram which shows the refrigerant | coolant flow at the time of simultaneous operation of cooling operation and heating operation. In the heat pump apparatus in Embodiment 2 of this invention, it is a circuit diagram which shows the refrigerant | coolant flow at the time of simultaneous operation of cooling operation and heating operation. It is a circuit diagram which shows the heat pump apparatus in Embodiment 3 of this invention. It is a Mollier diagram which shows the heat pump cycle by the heat pump apparatus in FIG. FIG. 7 is a diagram showing a flowchart of a method for controlling the amount of refrigerating machine oil in the cylinder of the high-stage compressor in the heat pump apparatus in FIG. 6. It is a circuit diagram which shows the heat pump apparatus in Embodiment 4 of this invention. In the heat pump apparatus in FIG. 9, it is a figure which shows the flowchart of the control method of the refrigerating machine oil amount in the cylinder of a high stage side compressor. It is a Mollier diagram for demonstrating the control performed in the heat pump apparatus in FIG. It is a circuit diagram which shows the heat pump apparatus in Embodiment 5 of this invention.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1 is a circuit diagram showing a refrigerant flow during heating operation (two-stage compression) in the heat pump apparatus according to Embodiment 1 of the present invention. FIG. 2 is a circuit diagram showing a refrigerant flow during heating operation (one-stage compression) in the heat pump apparatus according to Embodiment 1 of the present invention. FIG. 3 is a circuit diagram showing the refrigerant flow during the cooling operation in the heat pump apparatus according to Embodiment 1 of the present invention. FIG. 4 is a circuit diagram showing the refrigerant flow during the simultaneous operation of the cooling operation and the heating operation in the heat pump device according to Embodiment 1 of the present invention.

  1 to 4, heat pump device 10 in the present embodiment includes a refrigeration circuit 21, an injection circuit 22, a one-stage compression switching circuit 26, and a branch circuit 24 as its circuit configuration. In these circuits, for example, R410A is sealed as a refrigerant.

  The refrigeration circuit 21 extends in an annular shape and constitutes a heat pump cycle. On the path of the refrigeration circuit 21, a first usage side (indoor side) heat exchanger 33 and a heat source side (outside side) heat exchanger 37 are provided. The 1st utilization side heat exchanger 33 performs heat exchange between the refrigerant | coolant which circulates through a heat pump cycle, and utilization fluid (water or air). The heat source side heat exchanger 37 exchanges heat between the refrigerant circulating in the heat pump cycle and the heat source (outside air).

  On the path of the refrigeration circuit 21, a first decompressor 34, a gas-liquid separator 35, and a second decompressor 36 are further provided.

  The first decompression device 34, the gas-liquid separator 35, and the second decompression device 36 are provided between the first usage side heat exchanger 33 and the heat source side heat exchanger 37. On the path of the refrigeration circuit 21 from the first usage side heat exchanger 33 toward the heat source side heat exchanger 37, the first decompression device 34, the gas-liquid separator 35, and the second decompression device 36 are arranged in the order given. That is, the gas-liquid separator 35 is provided between the first use side heat exchanger 33 and the heat source side heat exchanger 37. The first decompression device 34 is provided between the first usage-side heat exchanger 33 and the gas-liquid separator 35. The second decompression device 36 is provided between the gas-liquid separator 35 and the heat source side heat exchanger 37.

  The configuration of the refrigeration circuit 21 will be described assuming the refrigerant flow during the heating operation (two-stage compression) shown in FIG. 1. The first decompression device 34 uses the refrigerant sent from the first use side heat exchanger 33. Reduce pressure. The first decompressor 34 is provided as a decompressor for controlling the supercooling of the refrigerant in the first usage-side heat exchanger 33.

  The gas-liquid separator 35 separates the refrigerant sent from the first decompression device 34 into a gas-phase refrigerant and a liquid-phase refrigerant (liquid refrigerant). The gas-liquid separator 35 includes a gas-phase refrigerant space 35a in which a gas-phase refrigerant is disposed, and a liquid-phase refrigerant space 35b in which a liquid-phase refrigerant is disposed.

  The second decompression device 36 is connected to the liquid phase refrigerant space 35b of the gas-liquid separator 35 through a pipe. The second decompression device 36 decompresses the liquid refrigerant sent from the gas-liquid separator 35. The second decompression device 36 is provided as a decompression device for controlling the degree of superheating of the refrigerant in the heat source side heat exchanger 37 and the amount of injection refrigerant by the injection circuit 22 described later. In the present embodiment, expansion valves are used as the first pressure reducing device 34 and the second pressure reducing device 36.

  On the path of the refrigeration circuit 21, a low-stage compressor 31 and a high-stage compressor 32 are further provided.

  The low stage side compressor 31 and the high stage side compressor 32 are provided between the heat source side heat exchanger 37 and the first usage side heat exchanger 33. On the path of the refrigeration circuit 21, the low-stage compressor 31 and the high-stage compressor 32 sandwich the first usage-side heat exchanger 33 and the heat source-side heat exchanger 37, and the first decompressor 34, the gas-liquid It is provided on the opposite side of the separator 35 and the second pressure reducing device 36. On the path of the refrigeration circuit 21 from the heat source side heat exchanger 37 toward the first usage side heat exchanger 33, the low stage side compressor 31 and the high stage side compressor 32 are arranged in the order given. That is, the low stage compressor 31 is provided between the heat source side heat exchanger 37 and the high stage compressor 32. The high stage side compressor 32 is provided between the low stage side compressor 31 and the use side heat exchanger 33.

  The low-stage compressor 31 is provided as a low-pressure compressor that compresses the low-pressure refrigerant sent from the heat source-side heat exchanger 37 to an intermediate pressure. The high-stage compressor 32 is provided as a high-pressure compressor that compresses the intermediate-pressure refrigerant sent from the low-stage compressor 31 to a higher pressure.

  In the present embodiment, the low-stage compressor 31 is a variable-capacity type compressor that can control the refrigerant discharge capacity (for example, an inverter-type compressor that can change the rotational speed), and the high-stage compressor The machine 32 is a constant speed type compressor. Note that at least one of the low-stage compressor 31 and the high-stage compressor 32 may be a variable capacity type, and the low-stage compressor 31 with a constant rotation speed and the variable-capacity high-stage compression. Or a combination of a variable capacity low-stage compressor 31 and a variable capacity high-stage compressor 32. When the low-stage compressor 31 is a variable capacity type, the operable range at high loads is widened.

  A four-way valve 44 is further provided on the path of the refrigeration circuit 21 to enable switching between heating (heating) operation and cooling (cooling) operation.

  The four-way valve 44 uses the refrigerant discharged by the low-stage compressor 31 and the high-stage compressor 32 (only the low-stage compressor 31 in the case of the single-stage compression operation) during the heating operation on the use-side heat exchanger 33. In the cooling operation, the refrigerant flow is controlled so that the refrigerant discharged by the low-stage compressor 31 is led to the heat source side heat exchanger 37.

  A first two-way valve 41 is further provided on the path of the refrigeration circuit 21. The first two-way valve 41 is provided in the refrigeration circuit 21 between the high stage side compressor 32 and the first usage side heat exchanger 33. The first two-way valve 41 is provided as an on-off valve that allows or blocks the refrigerant flow in the refrigeration circuit 21 between the high-stage compressor 32 and the first usage-side heat exchanger 33.

  The injection circuit 22 converts a part of the refrigerant separated into the gas-phase refrigerant space 35a of the gas-liquid separator 35 into the refrigeration circuit 21 (confluence position 28) between the low-stage compressor 31 and the high-stage compressor 32. ).

  More specifically, both ends of the injection circuit 22 are connected to the gas-phase refrigerant space 35 a of the gas-liquid separator 35 and the refrigeration circuit 21 between the low-stage compressor 31 and the high-stage compressor 32. It is provided to connect each. The refrigerant inlet of the injection circuit 22 is connected to the gas-phase refrigerant space 35a of the gas-liquid separator 35, and the refrigerant outlet (merging position 28) of the injection circuit 22 is connected to the low-stage compressor 31 and the high-stage compressor 32. Is connected to the refrigeration circuit 21 between the two.

  A second two-way valve 43 is provided on the path of the injection circuit 22. The second two-way valve 43 is provided as an on-off valve that allows or blocks the refrigerant flow in the injection circuit 22.

  The one-stage compression switching circuit 26 is provided to enable switching from the two-stage compression heating operation to the one-stage compression heating operation.

  More specifically, the first-stage compression switching circuit 26 bypasses the high-stage compressor 32 by bypassing the refrigerant discharged from the low-stage compressor 31 during the heating operation of the first-stage compression. It is provided to guide directly to the exchanger 33. The both ends of the first stage compression switching circuit 26 are the refrigeration circuit 21 between the first two-way valve 41 and the first use side heat exchanger 33, and the injection circuit between the second two-way valve 43 and the merge position 28. 22 are connected to each other.

  A third two-way valve 42 is provided on the path of the first stage compression switching circuit 26. The third two-way valve 42 is provided as an on-off valve that allows or blocks the refrigerant flow in the one-stage compression switching circuit 26.

  The branch circuit 24 is provided to branch from the refrigeration circuit 21 on the discharge side of the high stage compressor 32. The branch circuit 24 is connected to the injection circuit 22. More specifically, the branch circuit 24 is provided so as to branch from the refrigeration circuit 21 between the high-stage compressor 32 and the first two-way valve 41. The branch circuit 24 is connected to the injection circuit 22 between the gas-liquid separator 35 and the second two-way valve 43.

  On the path of the branch circuit 24, a second usage-side heat exchanger 38 and a third decompression device 39 are provided. The second usage-side heat exchanger 38 is provided between the branch position of the branch circuit 24 from the refrigeration circuit 21 and the third decompression device 39. The third decompression device 39 is provided between the second usage side heat exchanger 38 and the connection position of the branch circuit 24 to the injection circuit 22.

  The second usage-side heat exchanger 38 exchanges heat between the refrigerant circulating in the heat pump cycle and the usage fluid (water or air). The third decompression device 39 decompresses the refrigerant sent from the second usage side heat exchanger 38. The third decompression device 39 has a function of blocking the pipe line forming the branch circuit 24. That is, the third pressure reducing device 39 has both a function as a pressure reducing device and a function as an on-off valve capable of blocking the refrigerant flow in the branch circuit 24.

  In the heat pump device 10 according to the present embodiment, the heating operation (two-stage compression) by the first usage-side heat exchanger 33, the heating operation (first-stage compression) by the first usage-side heat exchanger 33, and the first usage side. Four operation modes can be selected: a cooling operation by the heat exchanger 33 (defrosting operation), a cooling operation by the first usage side heat exchanger 33, and a simultaneous operation of the heating operation by the second usage side heat exchanger 38. is there.

  A typical example of the simultaneous operation of the cooling operation and the heating operation is a combination in which cooling is performed in the first usage-side heat exchanger 33 and hot water is supplied in the second usage-side heat exchanger 38. The invention is not limited to such combinations.

  First, the refrigerant flow during the heating operation (two-stage compression) shown in FIG. 1 will be described. At this time, the first two-way valve 41, the second two-way valve 43, the third two-way valve 42, and the third pressure reducing device 39 are controlled to an open state, an open state, a closed state, and a closed state, respectively.

  In this operation mode, the gas refrigerant discharged from the high-stage compressor 32 flows into the first usage-side heat exchanger 33 and becomes condensed high-temperature liquid refrigerant. At this time, the utilization fluid is heated by heat radiation from the refrigerant to the utilization fluid. When the high-temperature liquid refrigerant passes through the first decompression device 34, the pressure and temperature of the refrigerant are reduced.

  Next, the refrigerant flows into the gas-liquid separator 35 and is separated into a gas phase and a liquid phase. As the separated liquid refrigerant passes through the second decompression device 36, the pressure and temperature of the refrigerant further decrease. Next, when the refrigerant passes through the heat source side heat exchanger 37, the refrigerant absorbs heat from the outside air and evaporates. The refrigerant flows into the low stage compressor 31 and is compressed to an intermediate pressure.

  On the other hand, a part of the refrigerant (injection refrigerant) separated into the gas-phase refrigerant space 35 a of the gas-liquid separator 35 passes through the injection circuit 22 and joins with the refrigerant discharged from the low-stage compressor 31. Join. Since the temperature of the injection refrigerant is lower than the temperature of the refrigerant discharged from the low-stage compressor 31, the refrigerant temperature after joining the injection refrigerant decreases.

  During the heating operation, the compression ratio increases when the outside air temperature becomes low and the evaporation pressure decreases, but after the compression step in the low-stage compressor 31 and before the compression step by the high-stage compressor 32. In the stage, by injecting the injection refrigerant into the intermediate pressure refrigerant and increasing the refrigerant flow rate, the heating capacity can be ensured without abnormally increasing the discharge temperature.

  Next, the refrigerant flow during the heating operation (one-stage compression) shown in FIG. 2 will be described based on the description of the refrigerant flow during the heating operation (two-stage compression). At this time, the first two-way valve 41, the second two-way valve 43, the third two-way valve 42, and the third pressure reducing device 39 are controlled to a closed state, a closed state, an open state, and a closed state, respectively.

  In the present operation mode, the refrigerant discharged from the low-stage compressor 31 passes through the injection circuit 22 and the first-stage compression switching circuit 26 in order from the joining position 28 to the first usage-side heat exchanger 33. As a result, the refrigerant discharged from the low-stage compressor 31 bypasses the high-stage compressor 32 and flows directly into the first usage-side heat exchanger 33.

  Next, the refrigerant flow during the cooling operation shown in FIG. 3 will be described based on the description of the refrigerant flow during the heating operation (two-stage compression). At this time, the first two-way valve 41, the second two-way valve 43, the third two-way valve 42, and the third pressure reducing device 39 are controlled to a closed state, a closed state, an open state, and a closed state, respectively.

  In this operation mode, the refrigerant discharged from the low-stage compressor 31 is converted into the heat source side heat exchanger 37, the second decompression device 36, the gas-liquid separator 35, the first decompression device 34, and the first usage side heat exchanger. 33 in order. In the 1st utilization side heat exchanger 33, utilization fluid is cooled by the heat absorption from utilization fluid to a refrigerant | coolant. The refrigerant that has flowed out of the first usage-side heat exchanger 33 passes through the first-stage compression switching circuit 26 and the injection circuit 22 in order, and again goes to the low-stage compressor 31.

  Next, the refrigerant flow during the simultaneous operation of the cooling operation and the heating operation shown in FIG. 4 will be described based on the description of the refrigerant flow during the heating operation (two-stage compression). At this time, the first two-way valve 41, the second two-way valve 43, the third two-way valve 42, and the third pressure reducing device 39 are controlled to a closed state, a closed state, an open state, and an open state, respectively.

  In this operation mode, the cooling flow for the cooling operation in the first usage-side heat exchanger 33 is the same as the refrigerant flow during the cooling operation shown in FIG.

  Furthermore, a part of the refrigerant that has flowed out of the first use side heat exchanger 33 is branched at the merge position 28 and heads toward the high stage compressor 32. The refrigerant compressed by the high stage side compressor 32 flows into the second usage side heat exchanger 38 through the branch circuit 24. In the second usage-side heat exchanger 38, the utilization fluid is heated by heat radiation from the refrigerant to the utilization fluid. The refrigerant flowing out from the second usage side heat exchanger 38 passes through the third decompression device 39 and is decompressed. The refrigerant is returned from the branch circuit 24 to the gas-liquid separator 35 on the refrigeration circuit 21 through the injection circuit 22.

  According to the heat pump device 10 according to Embodiment 1 of the present invention configured as described above, the amount of heat obtained by the refrigerant in the evaporation step in the first usage-side heat exchanger 33 during the simultaneous operation of the cooling operation and the heating operation, The heating operation by the second usage-side heat exchanger 38 is performed using the amount of heat obtained by the refrigerant in the compression step by the high stage compressor 32. Thereby, the simultaneous operation of the cooling operation and the heating operation can be realized by utilizing the low-stage compressor 31 and the high-stage compressor 32 for the two-stage compression.

(Embodiment 2)
FIG. 5 is a circuit diagram showing the refrigerant flow during the simultaneous operation of the cooling operation and the heating operation in the heat pump apparatus according to Embodiment 2 of the present invention. The heat pump device in the present embodiment basically has the same structure as the heat pump device 10 in the first embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  Referring to FIG. 5, in the present embodiment, branch circuit 24 is connected to refrigeration circuit 21 on the discharge side of low stage compressor 31. The branch circuit 24 is connected to the refrigeration circuit 21 between the low-stage compressor 31 and the four-way valve 44.

  In such a configuration, during the simultaneous operation of the cooling operation and the heating operation, the refrigerant that has flowed out of the third decompression device 39 in the branch circuit 24 merges with the refrigerant discharged from the low-stage compressor 31, and the refrigeration circuit 21. Returned to In the present embodiment, the low-stage compressor 31 and the high-stage compressor 32 are provided in parallel on the refrigeration circuit 21 between the first usage-side heat exchanger 33 and the heat source-side heat exchanger 37. Yes. Therefore, heat exchange must be performed between the refrigerant flowing in the second usage-side heat exchanger 38 and the usage fluid, for example, by stopping the fan or pump for feeding the usage fluid in the second usage-side heat exchanger 38. For example, the cooling capacity and the defrosting capacity in the first usage-side heat exchanger 33 can be improved.

  According to the heat pump device in the second embodiment of the present invention configured as described above, the effects described in the first embodiment can be similarly obtained.

  It is as follows when the structure and effect of this invention are demonstrated collectively. In addition, although the reference number as described in Embodiment 1-2 is attached | subjected to the structure of invention, this is an example.

  A heat pump device according to one aspect of the present invention is provided on a refrigeration circuit (21) constituting a heat pump cycle, and a heat source side heat exchanger (37) for exchanging heat between a refrigerant and a heat source, and a refrigeration circuit. (21) provided on the first usage side heat exchanger (33) for exchanging heat between the refrigerant and the used fluid, and the first usage side heat exchanger (33) provided on the refrigeration circuit (21). The refrigerant sent from the heat source side heat exchanger (37) during the heating operation in) is compressed, and the refrigerant sent from the first use side heat exchanger (33) during the cooling operation in the first use side heat exchanger (33). A low-stage compressor (31) that compresses, a high-stage compressor (32) that is provided on the refrigeration circuit (21) and compresses refrigerant sent from the low-stage compressor (31), and a high-stage side Branch from refrigeration circuit (21) on discharge side of compressor (32) That is provided to the branch circuit (24) on, comprising a second use-side heat exchanger for performing heat exchange between the refrigerant and utilize fluid and (38). During the simultaneous operation of the cooling operation in the first usage side heat exchanger (33) and the heating operation in the second usage side heat exchanger (38), a part of the refrigerant sent from the first usage side heat exchanger (33) The refrigerant, which is guided to the high stage compressor (32) and compressed by the high stage compressor (32), is sent to the second usage side heat exchanger (38) through the branch circuit (24).

  According to the heat pump device configured as described above, the refrigerant is used in the evaporation step in the first usage-side heat exchanger during the simultaneous operation of the cooling operation in the first usage-side heat exchanger and the heating operation in the second usage-side heat exchanger. The heating operation in the second usage side heat exchanger is performed using the amount of heat obtained and the amount of heat obtained by the refrigerant in the compression step by the high stage side compressor. Thereby, the heat pump apparatus which enabled simultaneous operation of cooling operation and heating operation using the low-stage side compressor and the high-stage side compressor for the two-stage compression can be realized.

  Preferably, the heat pump device is provided on the refrigeration circuit (21) between the first use side heat exchanger (33) and the heat source side heat exchanger (37), and separates the refrigerant into a gas phase and a liquid phase. Gas-liquid separator (35), a first decompression device (35) provided on the refrigeration circuit (21) between the first usage-side heat exchanger (33) and the gas-liquid separator (35), and decompresses the refrigerant. 34) and a second decompression device (36) provided on the refrigeration circuit (21) between the gas-liquid separator (35) and the heat source side heat exchanger (37) and decompressing the refrigerant. The branch circuit (24) converts a part of the gas-phase refrigerant separated by the gas-liquid separator (35) into a refrigeration circuit (31) between the low-stage compressor (31) and the high-stage compressor (32). 21) to the injection circuit (22) leading to 21).

  According to the heat pump device configured as described above, the refrigerant sent from the second usage-side heat exchanger is supplied at the same time as the cooling operation in the first usage-side heat exchanger and the heating operation in the second usage-side heat exchanger. Return to the refrigeration circuit through the injection circuit.

  Preferably, the heat pump device further includes a third decompression device (39) provided on the branch circuit (24) and decompressing the refrigerant sent from the second usage side heat exchanger (38).

  According to the heat pump device configured as described above, the refrigerant decompression ratio in the third decompression device is controlled during the simultaneous operation of the cooling operation in the first usage-side heat exchanger and the heating operation in the second usage-side heat exchanger. Thus, the amount of refrigerant flowing into the second usage side heat exchanger can be adjusted.

  Also preferably, the third pressure reducing device (39) has a function of blocking a pipe line forming the branch circuit (24).

  According to the heat pump device configured as described above, it is possible to block the refrigerant flow in the branch circuit according to the operation state of the heat pump device.

  Also preferably, the branch circuit (24) is connected to the refrigeration circuit (21) on the discharge side of the low stage compressor (31).

  According to the heat pump device configured as described above, the refrigerant sent from the second usage-side heat exchanger is supplied at the same time as the cooling operation in the first usage-side heat exchanger and the heating operation in the second usage-side heat exchanger. Return to the refrigeration circuit on the discharge side of the low-stage compressor. Further, if heat exchange is not performed between the second usage-side heat exchanger and the usage fluid, the first usage-side heat exchange is performed by a compression process using a high-stage compressor and a low-stage compressor connected in parallel. The cooling capacity in the vessel can be improved.

(Embodiment 3)
FIG. 6 is a circuit diagram showing a heat pump device according to Embodiment 3 of the present invention. Referring to FIG. 6, heat pump device 60 in the present embodiment is typically applied to a heat pump hot water heater or a heat pump heater. The heat pump device 60 includes a refrigeration circuit 21 and an injection circuit 22 as its circuit configuration. For example, R410A is sealed as a refrigerant in the refrigeration circuit 21 and the injection circuit 22.

  The refrigeration circuit 21 extends in an annular shape and constitutes a heat pump cycle. On the path of the refrigeration circuit 21, a use side (indoor side) heat exchanger 33 and a heat source side (outside side) heat exchanger 37 are provided. The use side heat exchanger 33 exchanges heat between the refrigerant circulating in the heat pump cycle and the use fluid (water or air). The heat source side heat exchanger 37 exchanges heat between the refrigerant circulating in the heat pump cycle and the heat source (outside air).

  On the path of the refrigeration circuit 21, a first decompressor 34, a gas-liquid separator 35, and a second decompressor 36 are further provided.

  The first decompression device 34, the gas-liquid separator 35 and the second decompression device 36 are provided between the use side heat exchanger 33 and the heat source side heat exchanger 37. On the path of the refrigeration circuit 21 from the use side heat exchanger 33 toward the heat source side heat exchanger 37, the first decompressor 34, the gas-liquid separator 35, and the second decompressor 36 are arranged in the order given. That is, the gas-liquid separator 35 is provided between the use side heat exchanger 33 and the heat source side heat exchanger 37. The first decompression device 34 is provided between the use side heat exchanger 33 and the gas-liquid separator 35. The second decompression device 36 is provided between the gas-liquid separator 35 and the heat source side heat exchanger 37.

  The first decompression device 34 decompresses the refrigerant sent from the use side heat exchanger 33. The first decompressor 34 is provided as a decompressor for controlling the supercooling of the refrigerant in the use side heat exchanger 33.

  The gas-liquid separator 35 separates the refrigerant sent from the first decompression device 34 into a gas-phase refrigerant and a liquid-phase refrigerant (liquid refrigerant). The gas-liquid separator 35 includes a gas-phase refrigerant space 35a in which a gas-phase refrigerant is disposed, and a liquid-phase refrigerant space 35b in which a liquid-phase refrigerant is disposed.

  The second decompression device 36 is connected to the liquid phase refrigerant space 35b of the gas-liquid separator 35 through a pipe. The second decompression device 36 decompresses the liquid refrigerant sent from the gas-liquid separator 35. The second decompression device 36 is provided as a decompression device for controlling the degree of superheat of the refrigerant in the heat source side heat exchanger 37 and the amount of the injection refrigerant by the injection circuit 22 described later. In the present embodiment, expansion valves are used as the first pressure reducing device 34 and the second pressure reducing device 36.

  On the path of the refrigeration circuit 21, a low-stage compressor 31 and a high-stage compressor 32 are further provided.

  The low stage side compressor 31 and the high stage side compressor 32 are provided between the heat source side heat exchanger 37 and the use side heat exchanger 33. On the path of the refrigeration circuit 21, the low-stage compressor 31 and the high-stage compressor 32 sandwich the use side heat exchanger 33 and the heat source side heat exchanger 37, and the first decompressor 34, the gas-liquid separator 35 and the second decompression device 36 on the opposite side. On the path of the refrigeration circuit 21 from the heat source side heat exchanger 37 toward the use side heat exchanger 33, the low stage compressor 31 and the high stage compressor 32 are arranged in the order given. That is, the low stage compressor 31 is provided between the heat source side heat exchanger 37 and the high stage compressor 32. The high stage side compressor 32 is provided between the low stage side compressor 31 and the use side heat exchanger 33.

  The low-stage compressor 31 is provided as a low-pressure compressor that compresses the low-pressure refrigerant sent from the heat source-side heat exchanger 37 to an intermediate pressure. The high-stage compressor 32 is provided as a high-pressure compressor that compresses the intermediate-pressure refrigerant sent from the low-stage compressor 31 to a higher pressure.

  In the present embodiment, the low-stage compressor 31 and the high-stage compressor 32 are variable capacity compressors that can control the refrigerant discharge capacity (for example, inverter-type compressors that can change the number of revolutions). It is.

  Refrigerating machine oil (lubricating oil) for lubricating a compression mechanism, a bearing and the like is accommodated in a cylinder of the compressor.

  The injection circuit 22 is composed of an injection conduit 23 through which a refrigerant can flow. The injection circuit 22 guides the refrigerant disposed in the gas-phase refrigerant space 35a of the gas-liquid separator 35 to the refrigeration circuit 21 (merging position 28) between the low-stage compressor 31 and the high-stage compressor 32. It is provided as follows.

  More specifically, both ends of the injection circuit 22 are connected to the gas-phase refrigerant space 35 a of the gas-liquid separator 35 and the refrigeration circuit 21 between the low-stage compressor 31 and the high-stage compressor 32. It is provided to connect each. The refrigerant inlet of the injection circuit 22 is connected to the gas-phase refrigerant space 35a of the gas-liquid separator 35, and the refrigerant outlet (merging position 28) of the injection circuit 22 is connected to the low-stage compressor 31 and the high-stage compressor 32. Is connected to the refrigeration circuit 21 between the two.

  A buffer unit 61 and a buffer unit 62 are further provided on the path of the refrigeration circuit 21. The buffer part 61 and the buffer part 62 are comprised by the accumulator which can store a liquid refrigerant. The buffer unit 61 is provided between the heat source side heat exchanger 37 and the low stage compressor 31 on the path of the refrigeration circuit 21. The buffer unit 62 is provided between the low-stage compressor 31 and the high-stage compressor 32 on the path of the refrigeration circuit 21. The buffer unit 62 is provided between the merging position 28 and the high stage compressor 32. The buffer unit 61 and the buffer unit 62 are provided to prevent liquid refrigerant from entering the low-stage compressor 31 and the high-stage compressor 32 and reducing the reliability of the compressor, respectively.

  The buffer unit 62 is provided with a return line for returning the refrigeration oil stored in the accumulator together with the liquid refrigerant into the cylinder of the high-stage compressor 32. The return pipe is connected to the bottom of the accumulator when the specific gravity of the refrigerating machine oil is larger than the specific gravity of the refrigerant, and is located vertically away from the bottom of the accumulator when the specific gravity of the refrigerating machine oil is smaller than the specific gravity of the refrigerant. It is connected to the.

  FIG. 7 is a Mollier diagram showing a heat pump cycle by the heat pump apparatus in FIG. 6.

  The Mollier diagram is also called a Ph diagram, and the vertical axis represents pressure [MPa] and the horizontal axis represents specific enthalpy [kJ / kg]. The Mollier diagram is a diagram showing characteristics unique to the refrigerant such as the pressure, specific enthalpy, temperature, phase state, enthalpy, and specific volume of the refrigerant used in the refrigeration cycle. The refrigerant states A to H shown in FIG. 7 correspond to the refrigerant states A to H in FIG. 6, respectively.

  6 and 7, first, the gas refrigerant (state A) discharged from the high-stage compressor 32 flows into the use-side heat exchanger (condenser) 33 and is condensed to a high-temperature liquid refrigerant. (State B). When this high-temperature liquid refrigerant passes through the first decompression device 34, the pressure and temperature of the refrigerant decrease (state C).

  Next, the refrigerant flows into the gas-liquid separator 35 and is separated into a gas phase and a liquid phase. When the separated liquid refrigerant (state D) passes through the second decompression device 36, the pressure and temperature of the refrigerant further decrease (state E). Next, when the refrigerant passes through the heat source side heat exchanger (evaporator) 37, the refrigerant absorbs heat from the outside air and evaporates (state F). The refrigerant in the state F flows into the low-stage compressor 31 and is compressed to an intermediate pressure (state G).

  On the other hand, the refrigerant (injection refrigerant) separated into the gas-phase refrigerant space 35 a of the gas-liquid separator 35 passes through the injection circuit 22 and merges with the refrigerant discharged from the low-stage compressor 31 at the merge position 28. Since the temperature of the injection refrigerant is lower than the temperature of the refrigerant discharged from the low-stage compressor 31, the refrigerant temperature after the injection refrigerant merges decreases (state H).

  During the heating operation, when the outside air temperature is low and the evaporation pressure is reduced, the compression ratio increases, but after the compression step by the low-stage compressor 31 and before the compression step by the high-stage compressor 32. By injecting the injection refrigerant into the intermediate pressure refrigerant in the stage to increase the refrigerant flow rate, the heating (heating) capability can be ensured without abnormally increasing the discharge temperature. Thus, due to the effect of the injection refrigerant, for example, even if the outside air temperature is an extremely low temperature of about −20 ° C., sufficient heating capacity can be obtained.

  The heat pump device 60 includes a control unit 50, a temperature detection unit 71 as a first temperature detection unit, and a temperature detection unit 72 as a second temperature detection unit.

  The temperature detector 71 is provided between the first pressure reducing device 34 and the gas-liquid separator 35. The temperature detector 71 is provided at the discharge position of the first pressure reducing device 34. The temperature detection unit 71 detects the temperature T1 of the refrigerant discharged from the first decompression device 34 and flowing into the gas-liquid separator 35. The temperature detector 72 is provided between the low-stage compressor 31 and the high-stage compressor 32. The temperature detector 72 is provided between the high stage compressor 32 and the merge position 28. The temperature detection unit 72 is provided between the buffer unit 62 and the merge position 28. The temperature detection unit 72 detects the temperature T2 of the refrigerant discharged from the low-stage compressor 31 and after the refrigerant flowing through the injection circuit 22 joins. The temperature detector 72 detects the refrigerant temperature T <b> 2 at the suction position of the high stage compressor 32.

  In the heat pump device 60, the control unit 50 determines the pressure reduction ratio and the high-stage compressor in the second decompression device 36 so that the refrigeration oil in the cylinder of the high-stage compressor 32 becomes equal to or greater than a predetermined amount of oil. 32 (hereinafter, control of at least one of the pressure reduction ratio in the second decompression device 36 and the discharge flow rate of the high-stage compressor 32 is also referred to as oil amount reduction avoidance control). ).

  In particular, in the present embodiment, the control unit 50 is based on the comparison between the refrigerant temperature T1 detected by the temperature detection unit 71 and the refrigerant temperature T2 detected by the temperature detection unit 72. It is determined whether or not the amount of refrigerating machine oil in the cylinder 32 is appropriate, and when it is determined that the amount is not appropriate, avoidance control for oil amount reduction is performed. Based on the difference between the refrigerant temperature T1 detected by the temperature detection unit 71 and the refrigerant temperature T2 detected by the temperature detection unit 72, the control unit 50 uses the refrigerating machine oil in the cylinder of the high-stage compressor 32. It is determined whether or not the amount of oil is appropriate, and if it is determined that the amount of oil is not appropriate, control for avoiding oil amount reduction is performed.

  Then, the control method of the amount of refrigeration oil in the cylinder of the high stage side compressor 32 is demonstrated concretely. First, since the rotation speed of the compressor is an operation amount that can adjust the heating capacity most directly, the rotation speed of the variable capacity type low stage compressor 31 is controlled according to the load. For example, the rotational speed of the low-stage compressor 31 is increased or decreased according to the deviation between the target heating temperature set by the user or the target heating temperature preset in the apparatus and the measured heating temperature.

  FIG. 8 is a diagram showing a flowchart of a method for controlling the amount of refrigerating machine oil in the cylinder of the high-stage compressor in the heat pump apparatus shown in FIG. The control flow shown in the figure is executed by the control unit 50.

  In order to determine whether or not the amount of refrigeration oil in the cylinder of the high-stage compressor 32 is appropriate, first, the temperature of the refrigerant between the first decompression device 34 and the gas-liquid separator 35 is detected by the temperature detector 71. T1 is detected, and the temperature detector 72 detects the refrigerant temperature T2 at the suction position of the high-stage compressor 32. The detected temperature T1 and temperature T2 are stored in the control unit 50 (S101).

Next, to determine a target refrigerant temperature _{T2 SP} at the suction position of the high-stage compressor 32 (S102).

On the refrigeration circuit 21, the refrigerant between the first pressure reducing device 34 provided with the temperature detector 71 and the gas-liquid separator 35 is in a gas-liquid two-phase state. Further, there is no decompression device between the position where the temperature detection unit 71 is provided and the position where the temperature detection unit 72 is provided, and the refrigerant pressure at both positions is the same. Furthermore, when the refrigerant is between the saturated vapor state and the gas-liquid two-phase state, the dryness of the refrigerant changes depending on the ratio between the gas phase and the liquid phase, but the temperature of the refrigerant does not change. For this reason, when it is desired to improve the heating capacity while preventing the liquid refrigerant from excessively flowing into the high-stage compressor 32, the target refrigerant temperature T2 _SP = T1 may be set.

Here, the target refrigerant temperature T2 _SP = T1 + α (α is arbitrarily set so that the amount of liquid refrigerant at the suction position of the high-stage compressor 32 does not decrease the refrigeration oil in the cylinder of the high-stage compressor 32. Set to a predetermined value) (S102). As an example, α is 5 ° C. α is preferably a value exceeding 0 ° C. and 10 ° C. or less, and more preferably a value exceeding 0 ° C. and 5 ° C. or less. In order to operate the compressor safely, α should be set larger, and in order to increase the heating capacity, α should be set smaller. The degree may be determined by reliability evaluation through experiments.

Then, comparing the temperature T2 and the target refrigerant temperature _{T2 SP} (S103). When satisfying the relationship of T2 <T2 _SP, as compared with the state refrigerant at the suction position of the high-stage compressor 32 is the target is shifted to the saturated vapor side, Therefore, the buffer portion 62 and the high-stage compressor 32 It is determined that the liquid refrigerant is excessively supplied.

If the amount of liquid refrigerant stored in the buffer unit 62 becomes excessive, the refrigerant flows violently inside the accumulator, so that the refrigeration oil is difficult to return from the buffer unit 62 to the high-stage compressor 32. Further, when the amount of the liquid refrigerant in the buffer unit 62 further increases and the liquid refrigerant is supplied from the buffer unit 62 to the high stage side compressor 32 through the return pipe line, the compression stage in the high stage side compressor 32 is accompanied. The refrigerating machine oil in the cylinder of the high stage compressor 32 is easily discharged together with the liquid refrigerant. Therefore, the control unit 50, when satisfying the relationship of T2 <T2 _SP, it is determined that the refrigerating machine oil amount in the cylinder of the high-stage compressor 32 is not appropriate, perform avoidance control of decreasing oil amount (S104) .

On the other hand, when satisfying the relationship of T2 ≧ _{T2 SP} in S103, it executes the subsequent step S105.

  After the refrigerant temperature is detected by the temperature detector 71 and the temperature detector 72, the system waits for t seconds (S105). Then, temperature T1 and temperature T2 are measured (S101), and the steps after S102 are repeated.

In the step shown in S102, when the refrigerant changes from a gas phase state to a saturated vapor state, the refrigerant temperature changes even at the same pressure, so that the change in the state can be detected. However, since the refrigerant temperature does not change even when the saturated vapor state changes to the gas-liquid two-phase state, the refrigerant temperature at the suction position of the high-stage compressor 32 is in spite of the inflow of the liquid refrigerant from the injection circuit 22. It does not change. In such a case, there is a method of determining that the gas-liquid two-phase state is exceeded beyond the saturated vapor state when the state of T2 _SP (T1) = T2 continues for a predetermined time β seconds. When the state of T2 _SP (T1) = T2 continues for β seconds, there is a high possibility that the liquid refrigerant is supplied from the buffer unit 62 to the high-stage compressor 32 through the return pipe. In this case, since the refrigeration oil is discharged from the high-stage compressor 32 together with the liquid refrigerant, there is a possibility that the refrigeration oil amount is suddenly reduced, and therefore, a greater control for avoiding the oil amount reduction is required. . As an example, β is 30 seconds.

  That is, in the heat pump device 60 according to the present embodiment, the degree of superheat of the heat source side heat exchanger 37 is determined by comparing the temperature T1 of the injection refrigerant with the temperature T2 of the refrigerant at the suction position of the high stage compressor 32. If it is possible, it is determined that the injection state is appropriate. On the other hand, if the degree of superheat of the heat source side heat exchanger 37 cannot be obtained or if such a situation continues for a certain period of time, the liquid refrigerant is excessive to the buffer unit 62 and the high stage compressor 32. The oil amount reduction avoidance control is performed on the assumption that the oil is supplied to the engine.

  The avoidance control of the oil amount decrease by the control unit 50 will be described. When the controller 50 determines that the amount of the refrigerating machine oil in the cylinder of the high-stage compressor 32 is not appropriate, the controller 50 increases the opening of the second decompression device 36 (decreases the decompression ratio of the refrigerant in the second decompression device 36). To do). As a result, the flow rate of the injection refrigerant decreases, and the state of the refrigerant at the suction position of the high-stage compressor 32 shifts to the superheated gas side. For this reason, excessive supply of the liquid refrigerant to the buffer unit 62 and the high-stage compressor 32 can be suppressed.

  In addition, when the control unit 50 determines that the amount of the refrigerating machine oil in the cylinder of the high stage side compressor 32 is not appropriate, the control unit 50 reduces the rotation speed of the high stage side compressor 32 (the refrigerant flow in the high stage side compressor 32). Reduce the discharge flow rate). As a result, a phenomenon in which the refrigerating machine oil in the cylinder of the high-stage compressor 32 flows out together with the liquid refrigerant with the compression process in the high-stage compressor 32 is less likely to occur.

  By performing avoidance control of these oil amount reductions, the amount of refrigerating machine oil in the cylinder of the high-stage compressor 32 can be maintained appropriately. As a result, regardless of the load of the compressor, it is possible to perform a safe operation by maintaining an appropriate amount of the injection refrigerant.

  If excessive supply of the liquid refrigerant to the buffer unit 62 and the high-stage compressor 32 is in progress, and if it is necessary to prevent the oil amount from being reduced immediately, the opening degree of the second decompression device 36 can be adjusted. The number of steps may be set to a larger value. Further, when it is desired to more reliably prevent the excessive supply of liquid refrigerant to the buffer unit 62 and the high-stage compressor 32, α may be set to a larger value in the step shown in S102.

  Next, the reason why the amount of refrigerating machine oil in the cylinder of the high-stage compressor 32 is appropriately maintained in the heat pump device 60 according to the present embodiment will be described.

  The supply of the injection refrigerant has the effect of increasing the heating capacity by increasing the refrigerant flow rate on the heating side, and further increases the limit of the operating pressure ratio of the compressor. In order to increase the refrigerant flow rate on the heating side, the liquid phase injection refrigerant is more effective than the gas phase injection refrigerant. However, if the liquid phase injection refrigerant is excessively supplied, there is a concern that COP (Coefficient Of Performance) is deteriorated and the reliability of the compressor is reduced due to liquid compression. That is, when the ratio of the liquid phase in the injection refrigerant is too large, the liquid refrigerant is excessively supplied to the buffer unit 62 and the high-stage compressor 32. In this case, at least one of a phenomenon in which the refrigeration oil is difficult to return from the buffer unit 62 to the high stage compressor 32 and a phenomenon in which the refrigeration oil in the cylinder of the high stage compressor 32 is easily discharged together with the liquid refrigerant. Is likely to have occurred.

  Therefore, in the heat pump device 60 according to the present embodiment, an injection refrigerant that can be easily determined based on a comparison between the refrigerant temperature T1 detected by the temperature detector 71 and the refrigerant temperature T2 detected by the temperature detector 72. By detecting this state change, it is determined whether or not the amount of refrigerating machine oil in the cylinder of the high-stage compressor 32 is appropriate. When the condensing temperature, the evaporation temperature, and the rotation speed of the compressor are the same, it can be said that the largest factor that determines the capacity of the heat pump cycle is the suction pressure of the high-stage compressor 32 (state H in FIG. 6). ). In the present embodiment, the refrigerant flow rate on the heating side can be increased and the heating capacity can be increased by increasing the flow rate of the injection refrigerant while keeping the amount of refrigeration oil in the cylinder of the high-stage compressor 32 properly. For this reason, it is possible to achieve a heating capacity equal to or higher than before while keeping the amount of refrigeration oil of the high-stage compressor 32 within the specification range.

  Moreover, in this Embodiment, in order to determine whether the oil quantity of the refrigerating machine oil in the cylinder of the high stage side compressor 32 is appropriate, without providing a new apparatus, the heat pump apparatus 60 has a simple configuration. Can be.

  It should be noted that a decompression device may be provided on the path of the injection circuit 22, and the avoidance control of the oil amount decrease may be performed by controlling the decompression ratio in the decompression device. In this case, the temperature detection unit 71 is provided so as to be able to detect the temperature of the refrigerant after being decompressed by the decompression device.

  According to the heat pump device 60 according to the third embodiment of the present invention configured as described above, a highly reliable operation can be realized by appropriately maintaining the amount of refrigeration oil in the high stage compressor 32. Can do.

(Embodiment 4)
FIG. 9 is a circuit diagram showing a heat pump device according to Embodiment 4 of the present invention. The heat pump device in the present embodiment basically has the same structure as that of the heat pump device 60 in the third embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  Referring to FIG. 4, the heat pump apparatus in the present embodiment further includes a temperature detection unit 76 as a third temperature detection unit and a pressure detection unit 77 in addition to temperature detection unit 71.

  The temperature detection unit 76 is provided between the high stage compressor 32 and the use side heat exchanger 33. The temperature detector 76 is provided at the discharge position of the high stage compressor 32. The temperature detector 76 detects the temperature T3 of the refrigerant discharged from the high stage compressor 32 and flowing into the use side heat exchanger 33. The pressure detection unit 77 is provided between the high stage compressor 32 and the use side heat exchanger 33. The pressure detector 77 is provided at the discharge position of the high stage compressor 32. The pressure detector 77 detects the pressure P of the refrigerant that is discharged from the high-stage compressor 32 and flows into the use-side heat exchanger 33.

  FIG. 10 is a diagram showing a flowchart of a method for controlling the amount of refrigerating machine oil in the cylinder of the high-stage compressor in the heat pump apparatus in FIG. 9. FIG. 11 is a Mollier diagram for explaining the control executed in the heat pump apparatus in FIG. 9.

  With reference to FIG. 9 to FIG. 11, in the present embodiment, first, the temperature detection unit 71 detects the temperature T1 of the refrigerant between the first decompression device 34 and the gas-liquid separator 35, and the temperature detection unit 76. Further, the refrigerant temperature T3 and pressure P of the discharge side of the high stage compressor 32 are detected by the pressure detector 77. The detected temperature T1, temperature T3, and pressure P are stored in the controller 50 (S201).

  Next, the temperature T1 of the refrigerant between the first pressure reducing device 34 and the gas-liquid separator 35 is regarded as the temperature at which the refrigerant is in a gas-liquid two-phase state, and from the temperature T1 using the physical property value of the refrigerant. An intermediate pressure line 301 (D → C → H → G) is defined on the ph diagram. Further, an isentropic line X ′ passing through the point A ′ determined from the temperature T3 and the pressure P is determined on the ph diagram. The intersection of the intermediate pressure line 301 and the isentropic line X ′ is the specific enthalpy H ′ at the suction position of the high-stage compressor 32 in the current cycle, and the intermediate pressure line 301 and the saturated vapor line 302 of the refrigerant The intersection is the specific enthalpy H of the refrigerant in the saturated vapor state (S202).

  In this case, when the isentropic line X ′ determined on the ph diagram overlaps the isentropic line X passing through the specific enthalpy H of the refrigerant in the saturated vapor state and satisfies the relationship of H ′ = H, The refrigerant at the suction position of the stage side compressor 32 is in a saturated vapor state. The isentropic line X ′ determined on the ph diagram is shifted to the outside of the saturated vapor line 302 from the isentropic line X (isentropic line X′1 in FIG. 11), and H ′> H When the above relationship is satisfied, the refrigerant at the suction position of the high-stage compressor 32 is in the superheated gas state. The isentropic line X ′ determined on the ph diagram is shifted to the inside of the saturated vapor line 302 from the isentropic line X (isentropic line X′2 in FIG. 11), and H ′ <H When the above relationship is satisfied, the refrigerant at the suction position of the high-stage compressor 32 is in a gas-liquid two-phase state and has a large liquid phase.

  Next, the control unit 50 compares H ′ with H + α (α is an arbitrarily determined value) (S203). When the relationship of H + α ≦ H ′ is satisfied, it is determined that the operation is performed without any problem while ensuring the degree of superheat in the compressor discharge section. When satisfying the relationship of H + α> H ′, the control unit 50 compares H and H ′ (S204). When the relationship of H−H ′ ≧ 0 (H ≧ H ′) is satisfied, the liquid refrigerant is excessively supplied to the buffer unit 62 and the high stage side compressor 32. At this time, it is determined that the amount of refrigerating machine oil in the cylinder of the high-stage compressor 32 is not appropriate, and control for avoiding oil amount reduction is performed (S205).

  Wait for t seconds after satisfying the relationship of H + α ≦ H ′ in step S203, satisfying the relationship of H−H ′ <0 (H <H ′) in step S204, and after each step of step S205. (S206). Thereafter, the temperatures T1 and T3 and the pressure P1 are measured (S201), and the steps after S202 are repeated to keep the amount of refrigeration oil in the cylinder of the high-stage compressor 32 properly.

  Thus, in the present embodiment, the injection refrigerant is based on the refrigerant temperature T1 detected by the temperature detector 71, the refrigerant temperature T3 detected by the temperature detector 76, and the pressure P detected by the pressure detector 77. By detecting this state change, it is determined whether or not the amount of refrigerating machine oil in the cylinder of the high-stage compressor 32 is appropriate.

  According to the heat pump device configured as described above in the fourth embodiment of the present invention, the effects described in the third embodiment can be obtained in the same manner.

  In particular, in this embodiment, since the ratio of the liquid phase in the gas-liquid two-phase refrigerant can be specified through specific enthalpy, it is possible to accurately detect that the liquid compression operation is being performed. It is possible to effectively prevent excessive spillage of the refrigerating machine oil.

  Moreover, in this Embodiment, although the pressure detection part 77 is newly added, when a heat pump apparatus is a water heater, the utilization side heat exchanger (condenser) 33 is a plate heat exchanger. In this case, even if the pressure detection unit 77 is not used, if the temperature detection unit is provided at the same location and the correlation between the temperature and the pressure is specified by an experiment, the same effect as when the pressure detection unit 77 is used is obtained. Can be obtained.

(Embodiment 5)
FIG. 12 is a circuit diagram showing a heat pump device according to Embodiment 5 of the present invention. The heat pump device according to the present embodiment basically has the same structure as that of the heat pump device according to the third embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  Referring to FIG. 12, the heat pump device in the present embodiment further includes a temperature detection unit 81 as a fourth temperature detection unit in addition to temperature detection unit 71 and temperature detection unit 72. The temperature detection unit 81 is provided on the injection circuit 22. The temperature detector 81 detects the temperature T4 of the refrigerant flowing through the injection circuit 22.

  The control method of the opening degree of the second decompression device 36 is basically the same as that shown in the flowchart in FIG. However, the refrigerant discharged from the first decompression device 34 is used to cool the pipe when the outside air temperature is low, or to exchange heat between the refrigerant flowing through the injection circuit 22 and the refrigerant flowing through the refrigeration circuit 21. In a cycle in which a heat exchanger is provided, there is a possibility that a supercooled state will occur due to heat exchange with the injection refrigerant, resulting in a liquid refrigerant state. At this time, it is difficult to regard the refrigerant temperature detected by the temperature detection unit 71 as the refrigerant temperature at the suction position of the high stage compressor 32. Even in such a case, in the present embodiment, the temperature detection unit 81 that detects the temperature of the refrigerant flowing through the injection circuit 22 is provided, so that the refrigerant temperature T4 flowing through the injection circuit 22 and the first pressure reducing device 34 are detected. Is compared with the refrigerant temperature T1 on the discharge side, and the refrigerant temperature in the gas-liquid two-phase state is determined.

  That is, when the relationship of T4 = T1 is satisfied, since the refrigerant at any detection position is in the gas-liquid two-phase state, T1 or T4 is used in step S102 in FIG. When the relationship of T1> T4 is satisfied, the refrigerant flowing through the injection circuit 22 may be in a supercooled state, so T1 is used in the step of S102 in FIG. When the relationship of T1 <T4 is satisfied, the refrigerant after the first pressure reducing device 34 may be supercooled and in a liquid refrigerant state due to the influence of the outside air temperature and the internal heat exchanger. T4 is used in this step.

  According to the heat pump device in the fifth embodiment of the present invention configured as described above, the effect described in the third embodiment can be similarly obtained.

  It is as follows when the structure and effect of this invention are demonstrated collectively. In addition, although the reference number as described in Embodiment 3-5 is attached | subjected to the structure of invention, this is an example.

  A heat pump device according to another aspect of the present invention includes a heat source side heat exchanger (37) that exchanges heat between a refrigerant and a heat source, and a use side heat exchanger that exchanges heat between the refrigerant and a use fluid. (33), a low stage compressor (31) that compresses the refrigerant sent from the heat source side heat exchanger (37), and a cylinder that stores the refrigeration oil, and is sent from the low stage compressor (31). A high-stage compressor (32) that compresses the refrigerant to be produced in the cylinder, a first decompressor (34) that decompresses the refrigerant sent from the use-side heat exchanger (33), and a first decompressor (34). A gas-liquid separator (35) that separates the refrigerant to be sent into a gas phase and a liquid phase, and is connected to the liquid phase side of the gas-liquid separator (35), and the refrigerant sent from the gas-liquid separator (35) is decompressed. Connected to the gas phase side of the second pressure reducing device (36) and the gas-liquid separator (35), An injection pipe (23) for leading the refrigerant sent from (35) onto a pipe line between the low-stage compressor (31) and the high-stage compressor (32), and refrigeration oil in the cylinder are determined in advance. A control unit (50) for controlling at least one of the pressure reduction ratio in the second pressure reducing device (36) and the discharge flow rate of the high stage compressor (32) so as to be equal to or greater than the amount of oil obtained.

  According to the heat pump device configured as described above, the refrigerant that joins the pipe line between the low-stage side compressor and the high-stage side compressor through the injection pipe line by controlling the pressure reduction ratio in the second pressure reducing apparatus. Further, the flow rate of the refrigerant discharged from the high stage compressor is suppressed by controlling the discharge flow rate of the high stage compressor. Thereby, the phenomenon that the refrigeration oil in the cylinder flows out together with the liquid refrigerant along with the compression process in the high stage compressor can be prevented, and the oil amount of the refrigeration oil in the high stage compressor can be kept appropriate.

  Preferably, the heat pump device is provided on a pipe line between the first decompression device (34) and the gas-liquid separator (35), and detects a temperature T1 of the refrigerant, a first temperature detection unit (71), A second is provided on a pipe line between the low-stage compressor (31) and the high-stage compressor (32), and detects a refrigerant temperature T2 after the refrigerant flowing through the injection pipe (23) merges. And a temperature detector (72). Based on the comparison between the refrigerant temperature T1 detected by the first temperature detector (71) and the refrigerant temperature T2 detected by the second temperature detector (72), the controller (50) It is determined whether or not the amount of the refrigerating machine oil is appropriate.

  Preferably, the controller (50) is configured such that the refrigerant temperature T2 detected by the second temperature detector (72) is equal to the refrigerant temperature T1 detected by the first temperature detector (71). When it lasts only for the predetermined time, it determines with the oil quantity of the refrigerating machine oil in a cylinder not being appropriate.

  Preferably, the heat pump device is provided on a pipe line between the first decompression device (34) and the gas-liquid separator (35), and detects a temperature T1 of the refrigerant, a first temperature detection unit (71), A third temperature detection unit (76) and a pressure detection unit provided on a pipe line between the high stage compressor (32) and the use side heat exchanger (33) and detecting the temperature T3 and the pressure P of the refrigerant, respectively. (77). In the p (pressure) -h (specific enthalpy) diagram, the controller (50) includes an intermediate pressure line determined from the refrigerant temperature T1 detected by the first temperature detector (71), and a third temperature detector ( 76) and the specific enthalpy H ′ from the intersection with the isentropic line passing through the point determined from the refrigerant temperature T3 and the pressure P detected by the pressure detector (77), and the specific enthalpy H ′ and the intermediate pressure line Whether or not the amount of the refrigerating machine oil in the cylinder is appropriate is determined based on the comparison with the specific enthalpy H of the saturated steam at.

  According to the heat pump device configured as described above, it is possible to determine whether or not the amount of the refrigerating machine oil in the cylinder of the high-stage compressor is appropriate with a simple configuration.

  Preferably, the heat pump device is a conduit between the low-stage compressor (31) and the high-stage compressor (32), and the refrigerant after the refrigerant flowing through the injection conduit (23) joins. Is further provided with a buffer part (62) for storing the liquid refrigerant. The buffer unit (62) has a return line for returning the refrigeration oil stored together with the liquid refrigerant to the high stage compressor (32).

  According to the heat pump device configured as described above, the amount of refrigeration oil in the high-stage compressor is appropriately maintained by returning the refrigeration oil stored in the buffer unit to the high-stage compressor through the return pipe. be able to.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is mainly applied to a two-stage compression heat pump apparatus including a lower stage compressor and a higher stage compressor on a refrigeration circuit constituting a heat pump cycle.

  10, 60 heat pump device, 21 refrigeration circuit, 22 injection circuit, 23 injection pipe, 24 branch circuit, 26 1-stage compression switching circuit, 28 merging position, 31 low-stage compressor, 32 high-stage compressor, 33 1 use side heat exchanger (use side heat exchanger), 34 first decompression device, 35 gas-liquid separator, 35a gas phase refrigerant space, 35b liquid phase refrigerant space, 36 second decompression device, 37 heat source side heat exchanger , 38 Second usage side heat exchanger, 39 Third pressure reducing device, 41 First two-way valve, 42 Third two-way valve, 43 Second two-way valve, 44 Four-way valve, 50 Control unit, 61, 62 Buffer unit 71, 72, 76, 81 Temperature detector, 77 Pressure detector, 301 Intermediate pressure line, 302 Saturated vapor line.

Claims (10)

A heat source side heat exchanger that is provided on the refrigeration circuit constituting the heat pump cycle and performs heat exchange between the refrigerant and the heat source;
A first usage-side heat exchanger that is provided on the refrigeration circuit and performs heat exchange between the refrigerant and the utilization fluid;
The refrigerant is provided on the refrigeration circuit and compresses the refrigerant sent from the heat source side heat exchanger during the heating operation in the first usage side heat exchanger, and the first usage during the cooling operation in the first usage side heat exchanger. A low-stage compressor that compresses the refrigerant sent from the side heat exchanger;
A high-stage compressor that is provided on the refrigeration circuit and compresses refrigerant sent from the low-stage compressor;
A second usage-side heat exchanger provided on a branch circuit branched from the refrigeration circuit on the discharge side of the high-stage compressor, and performing heat exchange between the refrigerant and the used fluid;
During the simultaneous operation of the cooling operation in the first usage side heat exchanger and the heating operation in the second usage side heat exchanger, a part of the refrigerant sent from the first usage side heat exchanger is the high stage compressor. And the refrigerant compressed by the high stage compressor is sent to the second usage side heat exchanger through the branch circuit. A gas-liquid separator that is provided on the refrigeration circuit between the first use side heat exchanger and the heat source side heat exchanger, and separates the refrigerant into a gas phase and a liquid phase;
A first decompression device provided on the refrigeration circuit between the first usage-side heat exchanger and the gas-liquid separator and decompressing the refrigerant;
A second decompression device that is provided on the refrigeration circuit between the gas-liquid separator and the heat source side heat exchanger and decompresses the refrigerant;
The branch circuit is connected to an injection circuit that guides a part of the gas-phase refrigerant separated by the gas-liquid separator to the refrigeration circuit between the low-stage compressor and the high-stage compressor. The heat pump device according to claim 1.   The heat pump device according to claim 1 or 2, further comprising a third decompression device that is provided on the branch circuit and decompresses the refrigerant sent from the second usage-side heat exchanger.   The heat pump device according to claim 3, wherein the third pressure reducing device has a function of blocking a pipe line forming the branch circuit.   The heat pump device according to any one of claims 1 to 4, wherein the branch circuit is connected to the refrigeration circuit on the discharge side of the low-stage compressor. A heat source side heat exchanger that exchanges heat between the refrigerant and the heat source;
A use side heat exchanger for exchanging heat between the refrigerant and the use fluid;
A low stage compressor that compresses the refrigerant sent from the heat source side heat exchanger;
A high-stage compressor having a cylinder for storing refrigerating machine oil, and compressing the refrigerant sent from the low-stage compressor in the cylinder;
A first decompression device that decompresses the refrigerant sent from the use side heat exchanger;
A gas-liquid separator that separates the refrigerant sent from the first decompression device into a gas phase and a liquid phase;
A second decompression device connected to the liquid phase side of the gas-liquid separator and decompressing the refrigerant sent from the gas-liquid separator;
An injection pipe connected to the gas phase side of the gas-liquid separator and guiding the refrigerant sent from the gas-liquid separator onto a pipe line between the low-stage compressor and the high-stage compressor;
A control unit that controls at least one of a pressure reduction ratio in the second pressure reducing device and a discharge flow rate of the high-stage compressor so that the refrigeration oil in the cylinder is equal to or greater than a predetermined amount of oil. , Heat pump device. A first temperature detector provided on a pipe line between the first pressure reducing device and the gas-liquid separator, and detecting a refrigerant temperature T1;
A second temperature detector provided on a pipe line between the low-stage compressor and the high-stage compressor, and detecting a temperature T2 of the refrigerant after the refrigerant flowing through the injection pipe has joined. Prepared,
The control unit is configured to provide the oil of the refrigerating machine oil in the cylinder based on the comparison between the refrigerant temperature T1 detected by the first temperature detection unit and the refrigerant temperature T2 detected by the second temperature detection unit. The heat pump device according to claim 1, wherein it is determined whether or not the amount is appropriate.   When the state in which the refrigerant temperature T2 detected by the second temperature detector is equal to the refrigerant temperature T1 detected by the first temperature detector continues for a predetermined time, the controller The heat pump device according to claim 7, wherein the amount of refrigerating machine oil in the cylinder is determined to be inappropriate. A first temperature detector provided on a pipe line between the first pressure reducing device and the gas-liquid separator, and detecting a refrigerant temperature T1;
A third temperature detection unit and a pressure detection unit that are provided on a pipe line between the high-stage compressor and the use-side heat exchanger and detect a refrigerant temperature T3 and a pressure P, respectively;
In the p (pressure) -h (specific enthalpy) diagram, the control unit includes an intermediate pressure line determined from the refrigerant temperature T1 detected by the first temperature detection unit, the third temperature detection unit, and the pressure detection. The specific enthalpy H ′ is identified from the intersection with the isentropic line passing through the point determined from the refrigerant temperature T3 and the pressure P detected by the section, and the specific enthalpy H ′ and the specific enthalpy of the saturated steam on the intermediate pressure line The heat pump device according to any one of claims 6 to 8, wherein whether or not the amount of the refrigerating machine oil in the cylinder is appropriate is determined based on a comparison with H. A conduit between the low-stage compressor and the high-stage compressor, which is provided on the conduit through which the refrigerant flowing after the refrigerant flowing through the injection conduit merges and stores liquid refrigerant The buffer part is further provided,
The heat pump device according to any one of claims 6 to 9, wherein the buffer unit has a return pipe that returns the refrigeration oil stored together with the liquid refrigerant to the high-stage compressor.

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