JP5306478B2 - Heat pump device, two-stage compressor, and operation method of heat pump device - Google Patents

Abstract

To improve the efficiency of a two-stage compressor and of a heat pump apparatus employing a two-stage compressor when a load is small. The heat pump apparatus includes a main refrigerant circuit formed by connecting a two-stage compressor 100, a first heat exchanger, a first expansion mechanism, and a second heat exchanger sequentially with piping. When a load is higher than a predetermined load, the two-stage compressor 100 discharges a refrigerant, which is compressed twice by a low-stage compressor portion 10 and a high-stage compressor portion 30, to the refrigerant circuit. When the load is lower than the predetermined load, the two-stage compressor 100 discharges the refrigerant compressed by the low-stage compressor portion 10 to the main refrigerant circuit while bypassing the high-stage compressor portion 30 so the refrigerant is not compressed by the high-stage compressor portion 30.

Description

  The present invention relates to a two-stage compressor in which two compression units are connected in series, and a heat pump apparatus using the two-stage compressor.

In a two-stage compressor in which a low-stage compression section and a high-stage compression section are connected in series, the low-stage compression section compresses the refrigerant sucked from the heat pump cycle up to a predetermined pressure (attainment pressure). This ultimate pressure is determined by setting the compression chamber volume of the low-stage compression unit and the compression chamber volume of the high-stage compression unit. The high stage compression unit further compresses the refrigerant compressed by the low stage compression unit. And the refrigerant | coolant compressed by the high stage compression part is discharged from the high stage compression part to the internal space of an airtight container, and is discharged from the internal space of an airtight container to a heat pump cycle.
As described above, in the two-stage compressor, the ultimate pressure in the low-stage compression section is determined by setting the compression chamber volume of the low-stage compression section and the compression chamber volume of the high-stage compression section. Therefore, depending on the operating conditions of the heat pump cycle, there may be an over-compressed state in which only the low-stage compression portion is compressed to the discharge pressure to be discharged to the heat pump cycle. In the overcompressed state, the compression work in the high-stage compression unit is wasted, and the efficiency of the compressor is deteriorated. Here, the overcompressed state is likely to occur when the load is small, such as when heating operation is performed when the outside air temperature is high. That is, the overcompressed state is a factor that causes a decrease in efficiency when the load is small.

  Patent Document 1 describes a two-stage compressor including a bypass path that connects a communication path for flowing a refrigerant from a low-stage compression section to a high-stage compression section and a discharge-side space of the high-stage compression section. In this two-stage compressor, when an over-compression state occurs, the refrigerant in the communication passage is caused to flow to the discharge side space of the high-stage compression section, bypassing the high-stage compression section. Thereby, the improvement of the efficiency in the case of becoming an overcompressed state is aimed at.

  Patent Document 2 describes a heat pump device including a release mechanism that returns a part of the refrigerant compressed by the low-stage compression unit to the suction side of the low-stage compression unit. In this heat pump device, when the load is low, the release mechanism is operated to improve the efficiency of the compressor when the load is low.

JP-A-5-133367 JP-A-2-11886

In the two-stage compressor described in Patent Document 1, the refrigerant discharged from the low-stage compression section passes through a narrow and long communication path, and then is discharged from the bypass path to the discharge-side space of the high-stage compression section. Pressure loss occurs when the refrigerant passes through the narrow and long communication path. Therefore, although effective for avoiding the temporary overcompression state, the effect of reducing the overcompression loss during steady operation is small.
In particular, when the load is small, the discharge pressure is low, so the specific volume of the refrigerant gas is large and the volume flow rate is large. Therefore, the pressure loss due to the shortage of the channel area is large.

  In the heat pump device described in Patent Document 2, the suction side and the discharge side of the low-stage compression unit are directly connected by operating the release mechanism, and a part of the refrigerant compressed by the low-stage compression unit is the suction side of the low-stage compression unit Return to. However, even when the release mechanism is operated, compression work of a certain amount or more is generated in the low-stage compression unit. Further, the refrigerant is heated by passing through the low-stage compression section, and so-called preheat loss occurs. That is, a loss (preheat loss) occurs due to the refrigerant being heated before being compressed by the high-stage compression unit. Therefore, the degree of efficiency improvement when the load is low is small.

  An object of the present invention is to improve efficiency when a load is small in a two-stage compressor and a heat pump device using the two-stage compressor.

The heat pump device according to this invention is
A main refrigerant circuit in which a compressor, a first heat exchanger, a first expansion mechanism, and a second heat exchanger are sequentially connected by piping;
The compressor is
A low-stage compression unit that compresses the refrigerant flowing in;
A high stage compression section for further compressing the refrigerant compressed by the low stage compression section;
In the first heat exchanger, a required load that is an amount of heat necessary to bring the temperature of the fluid that exchanges heat with the refrigerant flowing through the main refrigerant circuit to a predetermined temperature is higher than the preset first load. In this case, the refrigerant compressed by the low-stage compression unit and the high-stage compression unit is discharged to the main refrigerant circuit, and when the necessary load is lower than the first load, the low-stage compression unit And a bypass mechanism that bypasses the compressed refrigerant without being compressed by the high-stage compression section and discharges the refrigerant to the main refrigerant circuit.

  In the heat pump device according to the present invention, when the load is low, the refrigerant compressed by the low stage compression unit is bypassed without being compressed by the high stage compression unit and discharged to the main refrigerant circuit. Therefore, it is possible to reduce the overcompression loss that occurs when the load is low.

1 is a plan view of a two-stage compressor 100 according to Embodiment 1. FIG. FIG. 2 is a cross-sectional view taken along line A-A ′ in FIG. 1. FIG. 3 is an enlarged view of the compression mechanism unit 3 and the periphery of the compression mechanism unit 3 in FIG. 2. B-B 'sectional drawing in FIG. C-C 'sectional drawing in FIG. D-D 'sectional drawing in FIG. E-E 'sectional drawing in FIG. F-F 'sectional drawing in FIG. The figure which shows an example of the circuit structure of the heat pump apparatus which has an injection circuit. The Mollier diagram about the state of the refrigerant | coolant of the heat pump apparatus shown in FIG. FIG. 3 is a configuration diagram of a two-stage compressor 100 according to a second embodiment. Sectional drawing of the compression mechanism part 3 part of the two-stage compressor 100 which concerns on Embodiment 3. FIG. Explanatory drawing of the force concerning the low stage vane 13. FIG. The figure which shows the torque fluctuation | variation of a normal twin rotary compressor. The figure which shows the torque fluctuation at the time of carrying out normal driving | operation of the two-stage compressor 100 which concerns on Embodiment 1. FIG. The figure which shows the torque fluctuation | variation at the time of carrying out the overcompression relief driving | operation of the two-stage compressor 100 which concerns on Embodiment 1. FIG. The figure which shows the torque fluctuation at the time of carrying out the high stage side direct suction | inhalation driving | operation of the two-stage compressor 100 which concerns on Embodiment 2. FIG.

Embodiment 1 FIG.
In the first embodiment, a two-stage compressor 100 having a bypass port that bypasses the high-stage compression unit will be described.

FIG. 1 is a plan view of a two-stage compressor 100 according to the first embodiment.
FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG. In FIG. 2, the aa ′ cross section is shown for the intermediate connecting pipe 51 portion.
FIG. 3 is an enlarged view of the compression mechanism unit 3 and the periphery of the compression mechanism unit 3 in FIG. 2.
4 is a cross-sectional view taken along the line BB ′ in FIG. 5 is a cross-sectional view taken along the line CC ′ in FIG.
6 is a cross-sectional view taken along the line DD ′ in FIG.
7 is a cross-sectional view taken along line EE ′ in FIG.
8 is a cross-sectional view taken along the line FF ′ in FIG.

First, the configuration of the two-stage compressor 100 will be described.
As shown in FIG. 2, the two-stage compressor 100 includes two electric motors 2 including a stator 2 a and a rotor 2 b, a low-stage compression unit 10, and a high-stage compression unit 30. A compression mechanism unit 3 including a compression unit and a crankshaft 4 are provided. A discharge pipe 5 is inserted into the upper part of the sealed container 1. Furthermore, the lower part of the airtight container 1 forms the lubricating oil storage part 6, and lubricating oil is enclosed.
The two-stage compressor 100 includes a suction muffler 7 outside the sealed container 1. The suction muffler 7 is connected to the lower stage compression unit 10 of the compression mechanism unit 3 in the hermetic container 1 by a suction pipe 8.

As shown in FIG. 3, the low-stage compression unit 10 of the compression mechanism unit 3 closes the low-stage cylinder 11, the low-stage frame 14 that closes the upper side of the low-stage cylinder 11, and the lower side of the low-stage cylinder 11. A low-stage compression chamber 15 is formed by the intermediate partition plate 50. The low-stage compression unit 10 includes a low-stage rolling piston 12 that rotates eccentrically in the low-stage compression chamber 15, and a low-stage vane 13 that divides the low-stage compression chamber 15 into a suction-side space and a discharge-side space ( 7). A suction pipe 8 is connected to the low stage suction port 21 of the low stage compression chamber 15.
Similarly, the high stage compression unit 30 includes a high stage cylinder 31, a high stage frame 34 that closes the lower side of the high stage cylinder 31, and an intermediate partition plate 50 that closes the upper side of the high stage cylinder 31. A high-stage compression chamber 35 having a smaller volume than the compression chamber 15 is formed. The high stage compression unit 30 includes a high stage rolling piston 32 that rotates eccentrically in the high stage compression chamber 35, and a high stage vane 33 that divides the high stage compression chamber 35 into a suction side space and a compression side space (FIG. 8). See).
That is, the two-stage compressor 100 is a rotary two-stage compressor.
The eccentric directions of the low-stage rolling piston 12 and the high-stage rolling piston 32 are shifted by about 180 degrees (see FIGS. 7 and 8).

Further, the compression mechanism unit 3 forms a high-stage discharge space 40 between the low-stage cover 19 (low-stage discharge part) that forms the low-stage discharge space 20 between the low-stage frame 14 and the high-stage frame 34. A high-stage cover 39 (high-stage discharge part) to be formed is provided. Further, an intermediate connecting pipe 51 that connects the intermediate outlet 22 of the low stage cover 19 and the high stage suction port 41 of the high stage cylinder 31 is provided, and the low stage discharge space 20 and the high stage compression chamber 35 communicate with each other. Yes.
A low-stage discharge port 16 that connects the low-stage compression chamber 15 and the low-stage discharge space 20 is formed in the low-stage frame 14. The low-stage discharge port 16 is provided with a reed valve in which a low-stage discharge valve 17 and a low-stage valve presser 18 are attached by rivets 28 (see FIG. 6). Similarly, a high-stage discharge port 36 that connects the high-stage compression chamber 35 and the high-stage discharge space 40 is formed in the high-stage frame 34. The high stage discharge port 36 is provided with a reed valve to which a high stage discharge valve 37 and a high stage valve presser 38 are attached by rivets.
Further, the low-stage cover 19 is provided with a bypass port 23 that communicates the low-stage discharge space 20 and the discharge pressure space 53 that is the internal space of the sealed container 1. The bypass port 23 is provided with a reed valve to which a bypass valve 24 and a bypass valve presser 25 are attached by a rivet 29 (see FIG. 5). These are called bypass mechanisms.
The high stage frame 34, the high stage cylinder 31, the intermediate partition plate 50, the low stage cylinder 11, the low stage frame 14, and the low stage cover 19 are penetrated, and the high stage discharge space 40 and the discharge pressure space are passed through. A discharge passage 52 that communicates with 53 is provided.

  Further, as shown in FIG. 4, the low-stage cover 19 is provided with an injector 60. An injection pipe 61 is connected to the injector 60.

Next, the operation of the two-stage compressor 100 will be described.
When electric power is supplied, the electric motor 2 operates. The electric motor 2 and the compression mechanism unit 3 are connected by a crankshaft 4, and power generated by the electric motor 2 is transmitted to the compression mechanism unit 3 through the crankshaft 4. Specifically, when supplied with electric power, the rotor 2b of the electric motor 2 rotates. When the rotor 2b rotates, the crankshaft 4 fitted in the rotor 2b also rotates. When the crankshaft 4 rotates, the low-stage rolling piston 12 and the high-stage rolling piston 32 into which the crankshaft 4 is inserted rotate eccentrically inside the low-stage compression chamber 15 and the high-stage compression chamber 35, respectively. As the low stage rolling piston 12 and the high stage rolling piston 32 rotate eccentrically, the low stage compression unit 10 and the high stage compression unit 30 compress the refrigerant.

Next, the refrigerant flow in the two-stage compressor 100 will be described.
First, a low-pressure refrigerant flows into the suction muffler 7 from the outside. The low-pressure refrigerant flowing into the suction muffler 7 is sucked into the low-stage compression chamber 15 through the suction pipe 8. The low-pressure refrigerant sucked into the low stage compression chamber 15 is compressed to an intermediate pressure in the low stage compression chamber 15. When the refrigerant is compressed to an intermediate pressure, the low stage discharge valve 17 is opened due to the pressure difference between the refrigerant in the low stage compression chamber 15 and the refrigerant in the low stage discharge space 20, and the refrigerant in the low stage compression chamber 15 is low. Discharge from the stage discharge port 16 to the low stage discharge space 20. Here, the intermediate pressure is a pressure determined from the ratio between the volume of the suction chamber of the low-stage compression chamber 15 and the volume of the suction chamber of the high-stage compression chamber 35.
The intermediate pressure refrigerant discharged to the low stage discharge space 20 is sucked into the high stage compression chamber 35 through the intermediate connecting pipe 51. The intermediate-pressure refrigerant sucked into the high-stage compression chamber 35 is compressed to the discharge pressure in the high-stage compression chamber 35. When the refrigerant is compressed to the discharge pressure, the high stage discharge valve 37 is opened due to the pressure difference between the refrigerant in the high stage compression chamber 35 and the refrigerant in the high stage discharge space 40, and the refrigerant in the high stage compression chamber 35 becomes high. Discharge from the stage discharge port 36 to the high stage discharge space 40.
The refrigerant having the discharge pressure discharged to the high stage discharge space 40 is discharged to the discharge pressure space 53 above the low stage compression unit 10 via the discharge flow path 52. The refrigerant having the discharge pressure discharged into the discharge pressure space 53 is discharged from the discharge pipe 5 to the outside.
In addition, when the injection operation is performed in the heat pump apparatus including the two-stage compressor 100, the injection refrigerant is injected into the low-stage discharge space 20 from the injection pipe 61 illustrated in FIG. The injection refrigerant is mixed with the intermediate-pressure refrigerant discharged from the low-stage compression chamber 15 in the low-stage discharge space 20 and compressed by the high-stage compression unit 30.

When the load of the heat pump device 101 is small, an overcompressed state that becomes a discharge pressure may occur only by the compression by the low-stage compression unit 10. That is, the intermediate pressure of the refrigerant described above may be higher than the required discharge pressure.
In this case, the bypass valve 24 is opened by the pressure difference between the refrigerant in the low-stage discharge space 20 and the refrigerant in the discharge pressure space 53, and the refrigerant in the low-stage discharge space 20 is discharged from the bypass port 23 to the discharge pressure space 53. . That is, the refrigerant discharged from the low stage compression unit 10 to the low stage discharge space 20 is bypassed and discharged to the discharge pressure space 53 without being compressed by the high stage compression unit 30.
In the overcompressed state, only the compression by the low-stage compression unit 10 results in the discharge pressure. Therefore, the compression by the high-stage compression unit 30 is useless, and if the high-stage compression unit 30 performs compression, the efficiency deteriorates. However, in the two-stage compressor 100, the refrigerant compressed by the low-stage compression unit 10 is discharged by bypassing the high-stage compression unit 30 when the over-compression state occurs. Therefore, loss (overcompression loss) when an overcompressed state occurs can be suppressed.

  In particular, the bypass port 23 is provided in the low stage cover 19. Therefore, the refrigerant discharged from the bypass port 23 to the discharge pressure space 53 is discharged to the discharge pressure space 53 in the sealed container 1 without passing through the intermediate connecting pipe 51. That is, the refrigerant discharged from the bypass port 23 to the discharge pressure space 53 is discharged from the bypass port 23 to the discharge pressure space 53 without causing a compression loss by passing through the narrow and long intermediate connecting pipe 51. Therefore, over-compression loss can be effectively suppressed during steady operation.

In addition, as mentioned above, the lower side of the airtight container 1 forms the lubricating oil storage part 6, and lubricating oil is enclosed. Since the lubricating oil is supplied to the mechanical portion of the compression mechanism unit 3, an amount of at least the compression unit disposed in the upper side (the low-stage compression unit 10 in FIG. 2) is enclosed.
In a general two-stage compressor, the low-stage compression unit is provided below the high-stage compression unit. Therefore, the low stage discharge space is provided below the low stage compression section. That is, the low stage cover is provided below the low stage compression unit. Accordingly, the low-stage discharge cover is immersed in the lubricating oil. In this case, the lubricating oil may enter the low-stage discharge space from the bypass port 23, or the lubricating oil may be wound up when the refrigerant is discharged from the bypass port 23, thereby increasing the outflow of the lubricating oil from the compressor. is there. For this reason, a bypass port cannot be provided in the low-stage cover, and as in Patent Document 1, the bypass port must be provided in a narrow and narrow flow path that connects the low-stage discharge space and the high-stage compression unit.
However, in the two-stage compressor 100, the low-stage compressor 10 is provided on the upper side of the high-stage compressor 30, contrary to the normal case. Therefore, the low-stage discharge space 20 is provided on the upper side of the low-stage compression unit 10, and the low-stage cover 19 can have a height that does not immerse in the lubricating oil. As a result, the bypass port 23 can be provided in the low stage cover 19.

  Further, since the bypass port 23 is provided in the low stage cover 19 instead of the intermediate connecting pipe 51, the bypass valve 24 can be a reed valve having a simple structure. Therefore, the bypass valve 24 and the bypass valve presser 25 can be made the same parts as the low-stage discharge valve 17 and the low-stage valve presser 18. Costs can be kept low by sharing parts. Further, since the structure of the bypass valve 24 is simplified, the cost for assembly can be reduced.

Next, the heat pump apparatus 101 including the two-stage compressor 100 will be described.
FIG. 9 is a diagram illustrating an example of a circuit configuration of a heat pump apparatus having an injection circuit. FIG. 10 is a Mollier diagram of the refrigerant state of the heat pump apparatus 101 shown in FIG. In FIG. 10, the horizontal axis represents specific enthalpy and the vertical axis represents refrigerant pressure.

  The heat pump device 101 includes a two-stage compressor 100, a heat exchanger 71 (second heat exchanger), a first expansion valve 72, a receiver 78, a third expansion valve 74, and a heat exchanger 76 (first heat exchanger). It has a main refrigerant circuit that is sequentially connected by piping. In addition, the heat pump apparatus 101 connects an injection circuit including a second expansion valve 75 in the middle of the pipe by connecting the pipe between the receiver 78 and the third expansion valve 74 to the injection pipe 61 of the two-stage compressor 100. Prepare. The heat pump device 101 includes an internal heat exchanger 73 that exchanges heat between the refrigerant in the main refrigerant circuit and the refrigerant in the injection circuit. Furthermore, the heat pump device 101 includes a four-way valve 77 that changes the direction in which the refrigerant flows.

First, the operation | movement at the time of the heating operation of the heat pump apparatus 101 is demonstrated. During the heating operation, the four-way valve 77 is set in the solid line direction. The heating operation includes not only heating used for air conditioning, but also hot water supply that heats water to make hot water.
The gas-phase refrigerant (point 1 in FIG. 10) that has become high temperature and high pressure in the two-stage compressor 100 is discharged from the discharge pipe 5 of the two-stage compressor 100 and is heated by the heat exchanger 71 that is a condenser and a radiator. It is exchanged and liquefied (point 2 in FIG. 10). At this time, air or water is warmed by heat radiated from the refrigerant, and heating or hot water is supplied.
The liquid-phase refrigerant liquefied by the heat exchanger 71 is depressurized by the first expansion valve 72 (decompression mechanism) and becomes a gas-liquid two-phase state (point 3 in FIG. 10). The refrigerant in the gas-liquid two-phase state by the first expansion valve 72 is heat-exchanged with the refrigerant sucked into the two-stage compressor 100 by the receiver 78, cooled and liquefied (point 4 in FIG. 10). The liquid-phase refrigerant liquefied by the receiver 78 branches and flows into the internal heat exchanger 73, the main refrigerant circuit on the third expansion valve 74 side, and the injection circuit on the second expansion valve 75 side.
The liquid-phase refrigerant flowing through the main refrigerant circuit is heat-exchanged by the internal heat exchanger 73 with the refrigerant flowing through the injection circuit that has been decompressed by the second expansion valve 75 and is in a gas-liquid two-phase state, and further cooled (FIG. 10). Point 5). The liquid-phase refrigerant cooled by the internal heat exchanger 73 is decompressed by the third expansion valve 74 (decompression mechanism) and becomes a gas-liquid two-phase state (point 6 in FIG. 10). The refrigerant in the gas-liquid two-phase state by the third expansion valve 74 is heat-exchanged and heated by the heat exchanger 76 serving as an evaporator (point 7 in FIG. 10). The refrigerant heated by the heat exchanger 76 is further heated by the receiver 78 (point 8 in FIG. 10), and is sucked into the two-stage compressor 100 from the suction pipe 8.
On the other hand, as described above, the refrigerant flowing through the injection circuit is decompressed by the second expansion valve 75 (decompression mechanism) (point 9 in FIG. 10) and is heat-exchanged by the internal heat exchanger 73 (point in FIG. 10). 10). The gas-liquid two-phase refrigerant (injection refrigerant) heat-exchanged by the internal heat exchanger 73 flows into the low-stage discharge space 20 from the injection pipe 61 of the two-stage compressor 100 in the gas-liquid two-phase state.
In the two-stage compressor 100, the refrigerant (point 8 in FIG. 10) flowing through the main refrigerant circuit and sucked from the suction pipe 8 is compressed and heated to an intermediate pressure by the low-stage compressor 10 (point 11 in FIG. 10). ). The refrigerant discharged to the low-stage discharge space 20 compressed and heated to the intermediate pressure (point 11 in FIG. 10) and the injection refrigerant (point 8 in FIG. 10) merge to lower the temperature (FIG. 10). Point 12). Then, the refrigerant whose temperature has decreased (point 12 in FIG. 10) is further compressed and heated by the high-stage compression unit 30 to become high temperature and pressure, and is discharged from the discharge flow path 52 to the discharge pressure space 53 (point 1 in FIG. 10). ).

When the injection operation is not performed, the opening of the second expansion valve 75 is fully closed. That is, when the injection operation is performed, the opening degree of the second expansion valve 75 is larger than the predetermined opening degree. However, when the injection operation is not performed, the opening degree of the second expansion valve 75 is predetermined. The opening is smaller than. Thereby, the refrigerant does not flow into the injection pipe 61 of the two-stage compressor 100. That is, all the refrigerant that has passed through the heat exchanger 71, the first expansion valve 72, and the receiver 78 is sucked into the two-stage compressor 100 from the suction pipe 8.
Here, the opening degree of the second expansion valve 75 is controlled by electronic control by the control unit. The control unit is, for example, a microcomputer.

Next, the operation | movement at the time of the cooling operation of the heat pump apparatus 101 is demonstrated. During the cooling operation, the four-way valve 77 is set in a broken line direction.
The gas-phase refrigerant (point 1 in FIG. 10) that has become high temperature and high pressure in the two-stage compressor 100 is discharged from the discharge pipe 5 of the two-stage compressor 100 and is heated by the heat exchanger 76 that is a condenser and a radiator. It is exchanged and liquefied (point 2 in FIG. 10). The liquid-phase refrigerant liquefied by the heat exchanger 76 is decompressed by the third expansion valve 74 and becomes a gas-liquid two-phase state (point 3 in FIG. 10). The refrigerant in the gas-liquid two-phase state by the third expansion valve 74 is heat-exchanged by the internal heat exchanger 73, cooled and liquefied (point 4 in FIG. 10). In the internal heat exchanger 73, the refrigerant that has become a gas-liquid two-phase state by the third expansion valve 74 and the liquid-phase refrigerant that has been liquefied by the internal heat exchanger 73 are decompressed by the second expansion valve 75, and the gas-liquid two-phase Heat is exchanged with the refrigerant in the state (point 9 in FIG. 10). The liquid refrigerant (point 4 in FIG. 10) heat-exchanged by the internal heat exchanger 73 branches and flows into the main refrigerant circuit on the receiver 78 side and the injection circuit on the internal heat exchanger 73 side.
The liquid-phase refrigerant flowing through the main refrigerant circuit is heat-exchanged with the refrigerant sucked into the two-stage compressor 100 by the receiver 78 and further cooled (point 5 in FIG. 10). The liquid-phase refrigerant cooled by the receiver 78 is decompressed by the first expansion valve 72 and becomes a gas-liquid two-phase state (point 6 in FIG. 10). The refrigerant in the gas-liquid two-phase state by the first expansion valve 72 is heat-exchanged and heated by the heat exchanger 71 serving as an evaporator (point 7 in FIG. 10). At this time, the refrigerant absorbs heat, thereby cooling air, water, etc., cooling, making cold water or ice, and freezing.
Then, the refrigerant heated by the heat exchanger 71 is further heated by the receiver 78 (point 8 in FIG. 10), and is sucked into the two-stage compressor 100 from the suction pipe 8.
On the other hand, as described above, the refrigerant flowing through the injection circuit is decompressed by the second expansion valve 75 (point 9 in FIG. 10) and is heat-exchanged by the internal heat exchanger 73 (point 10 in FIG. 10). The gas-liquid two-phase refrigerant (injection refrigerant) heat-exchanged by the internal heat exchanger 73 flows into the low-stage discharge space 20 from the injection pipe 61 of the two-stage compressor 100 in the gas-liquid two-phase state.
The compression operation in the two-stage compressor 100 is the same as in the heating operation.

  When the injection operation is not performed, the opening of the second expansion valve 75 is fully closed so that the refrigerant does not flow into the injection pipe 61 of the two-stage compressor 100 as in the heating operation.

  Further, as described above, the heat exchanger 71 may be a heat exchanger that performs heat exchange between a gas phase refrigerant that has become high temperature and pressure or a liquid phase refrigerant that has become low temperature and low pressure and a liquid such as water. Moreover, the heat exchanger 71 may be a heat exchanger that performs heat exchange between a gas-phase refrigerant that has become high temperature and pressure or a liquid-phase refrigerant that has become low temperature and low pressure and a gas such as air. That is, the heat pump apparatus 101 described in FIG. 9 may be an air conditioner, a hot water supply apparatus, a refrigeration apparatus, or a refrigeration apparatus.

Here, the injection operation is performed when the load is high. The load is a necessary load that is an amount of heat necessary to bring the temperature of the fluid that exchanges heat with the refrigerant flowing through the main refrigerant circuit in the heat exchanger 71 to a predetermined temperature. The required load can be measured by using the outside air temperature, the rotational speed of the compressor, or the like as an index. Here, it is assumed that a required load detection unit (not shown) detects the required load by detecting the outside air temperature, the rotational speed of the compressor, and the like.
For example, in the case of heating operation, the injection operation is performed when the outside air temperature is equal to or lower than a predetermined temperature (for example, 2 ° C.) or when the rotational speed of the compressor is equal to or higher than a predetermined frequency (for example, 60 Hz). Thereby, the heating capability at the time of low outside temperature can be made high, and the heat pump apparatus with a good heating and hot water supply performance is obtained. In other cases where the injection operation is not necessary, the opening of the second expansion valve 75 is fully closed and the injection operation is not performed even during the heating operation.

  Moreover, as above-mentioned, as for the two-stage compressor 100, when a load becomes low and it will be in an overcompression state, a bypass mechanism will operate | move. Then, the refrigerant compressed by the low-stage compression unit 10 bypasses without being compressed by the high-stage compression unit 30, is discharged to the discharge pressure space 53, and is discharged from the discharge pipe 5 to the refrigerant circuit.

That is, the heat pump device 101 performs the following operation control (1) to (3) according to the load height.
(1) When the load is high (when the load is higher than a preset second load), the opening of the second expansion valve 75 is increased and the injection operation is performed.
(2) When the load is medium (when the load is lower than the second load and higher than the first load set lower than the second load), the opening of the second expansion valve 75 The low-stage compression unit 10 and the high-stage compression unit 30 perform two-stage compression without reducing the injection operation.
(3) When the load is low (when the load is lower than the first load), the bypass valve 24 opens to bypass the high-stage compression unit 30 and compress mainly by the low-stage compression unit 10.
As a result, when the load is high, it is possible to perform an operation that exhibits a high capacity, and when the load is low, it is possible to perform an efficient operation while suppressing the capacity.

Embodiment 2. FIG.
In the second embodiment, a description will be given of a two-stage compressor 100 having a mechanism that causes the refrigerant flowing into the suction muffler 7 to be sucked into the high-stage compression section 30 by bypassing the low-stage compression section 10.

FIG. 11 is a configuration diagram of the two-stage compressor 100 according to the second embodiment.
Only the difference between the two-stage compressor 100 according to the second embodiment and the two-stage compressor 100 according to the first embodiment will be described.
The two-stage compressor 100 includes a suction pipe 8 that connects the suction muffler 7 and the low-stage suction port 21 of the low-stage compression unit 10, an intermediate outlet 22 of the low-stage cover 19, and a high stage of the high-stage compression unit 30. A four-way valve 54 (switching unit) is provided in the middle of the intermediate connecting pipe 51 that connects the suction port 41.
The four-way valve 54 connects the suction muffler 7 and the low-stage suction port 21, and connects the intermediate outlet 22 and the high-stage suction port 41 (flow path indicated by a solid line), and the suction muffler 7 and the high-stage suction port. While switching the port 41, the state (flow path shown with a broken line) which connected the low-stage inlet 21 and the intermediate | middle outlet 22 is switched. In particular, during normal operation, the four-way valve 54 connects the suction muffler 7 and the low-stage suction port 21 and connects the intermediate outlet 22 and the high-stage suction port 41 (flow path indicated by a solid line). On the other hand, when the load is low, the suction muffler 7 and the high-stage suction port 41 are connected, and the low-stage suction port 21 and the intermediate outlet 22 are connected (flow path indicated by a broken line). That is, during normal operation, the refrigerant flowing into the suction muffler 7 is sucked into the low-stage compression unit 10, and when the load is low, the refrigerant flowing into the suction muffler 7 is bypassed without being compressed by the low-stage compression unit 10. And sucked into the high-stage compression unit 30.

As a result, the two-stage compressor 100 according to the second embodiment has only a high-stage compressor 30 when the load is low and it is not necessary to compress both the low-stage compressor 10 and the high-stage compressor 30. The refrigerant can be compressed. Therefore, the two-stage compressor 100 can improve the compressor efficiency when the load is low.
Further, since the two-stage compressor 100 according to Embodiment 2 can cause the refrigerant flowing into the suction muffler 7 to be directly sucked into the high-stage compression unit 30 without passing through the low-stage compression unit 10, the low-stage compressor Preheat loss due to the compression unit 10 does not occur.

In the so-called inverter type compressor in which the operating rotational speed of the electric motor can be changed, the refrigerant circulation amount is adjusted by changing the rotational speed of the electric motor according to the load fluctuation of the heat pump device. That is, when the load is low and the refrigerant circulation amount must be reduced, the refrigerant circulation amount is reduced by reducing the number of revolutions of the electric motor. On the other hand, when the load is high and the refrigerant circulation amount must be large, the refrigerant circulation amount is increased by increasing the number of revolutions of the electric motor.
In general, the efficiency characteristics of an electric motor are designed to reach a peak at the rated rotational speed. Therefore, it is desirable from the viewpoint of compressor efficiency to operate the electric motor at a rotational speed close to the rated rotational speed.

As described in the first embodiment, when the load is low, the two-stage compressor 100 can compress the refrigerant mainly by the low-stage compression unit 10 by discharging the refrigerant from the bypass port 23. is there. In the second embodiment, as described above, the two-stage compressor 100 can compress the refrigerant only by the high-stage compression unit 30 by switching the four-way valve 54 when the load is low. That is, the two-stage compressor 100 can mainly compress the refrigerant only by the low-stage compressor 10 or can compress the refrigerant only by the high-stage compressor 30.
Here, as described in the first embodiment, the compression chamber volume of the high-stage compression unit 30 (volume of the high-stage compression chamber 35) is the compression chamber volume of the low-stage compression unit 10 (volume of the low-stage compression chamber 15). Smaller than. In order to obtain the same refrigerant circulation amount in a compressor having a large compression chamber volume and a compressor having a small compression chamber volume, the number of revolutions of the motor in the compressor having a large compression chamber volume is set to the electric motor in the compressor having a small compression chamber volume. It is necessary to make it less than the number of rotations. That is, in order to obtain the same refrigerant circulation amount in the two-stage compressor 100, the compression is mainly performed when the refrigerant is mainly compressed only by the low-stage compression unit 10 as compared with the case where the refrigerant is compressed only by the high-stage compression unit 30. Since the chamber volume is large, it is necessary to reduce the rotation speed of the electric motor.
Therefore, when the load is low, the two-stage compressor 100 mainly compresses the refrigerant only by the low-stage compression unit 10 and compresses the refrigerant only by the high-stage compression unit 30 according to the degree of low load. Switch to driving. Specifically, when the degree of low load is weak, the four-way valve 54 is not switched, and the refrigerant is mainly compressed only by the low-stage compression unit 10 by operating the bypass mechanism. On the other hand, when the degree of low load is strong (that is, when the load is very low), the four-way valve 54 is switched and the refrigerant is compressed only by the high-stage compression unit 30.
That is, when the refrigerant is compressed by the low-stage compression unit 10, the four-way valve 54 is switched so that the compression is performed only by the high-stage compression unit 30 when the rotation speed must be less than the rated rotation speed. Thereby, the rotation speed of an electric motor can be increased and the rotation speed of an electric motor can be closely approached to a rated rotation speed. As a result, efficiency can be improved.

That is, the heat pump apparatus 101 including the two-stage compressor 100 according to the second embodiment performs operation control from (1) to (4) according to the load.
(1) When the load is high (when the load is higher than a preset second load), the opening of the second expansion valve 75 is increased and the injection operation is performed.
(2) When the load is medium (when the load is lower than the second load and higher than the first load set lower than the second load), the second expansion valve 75 is opened. The two-stage compression is performed by the low-stage compression section 10 and the high-stage compression section 30 without reducing the degree and performing the injection operation.
(3) When the load is low (when the load is lower than the first load and higher than the third load set lower than the first load), the bypass valve 24 is opened to perform high-stage compression. The compression is mainly performed only by the low-stage compression unit 10 by bypassing the unit 30.
(4) When the load is very low (when the load is lower than the third load), the four-way valve 54 is switched to bypass the low-stage compressor 10 and from the suction muffler 7 to the high-stage compressor 30. The refrigerant is sucked and compressed only by the high stage compression unit 30.

Thereby, the heat pump apparatus 101 provided with the two-stage compressor 100 which concerns on Embodiment 2 can improve the efficiency in case a load is very low.
The four-way valve 54 is electronically controlled by the control unit.

Embodiment 3 FIG.
In the third embodiment, a description will be given of a two-stage compressor 100 that supplies the suction refrigerant of the high-stage compression unit 30 to the low-stage back pressure chamber 26 of the low-stage vane 13 of the low-stage compression unit 10.

FIG. 12 is a cross-sectional view of the compression mechanism section 3 portion of the two-stage compressor 100 according to the third embodiment.
Only the parts different from the two-stage compressor 100 according to the second embodiment will be described with respect to the two-stage compressor 100 according to the third embodiment.
The two-stage compressor 100 passes through the intermediate partition plate 50 and has a high-stage suction channel 42 between the high-stage suction port 41 and the high-stage compression chamber 35, and the low-stage back pressure chamber of the low-stage compression unit 10. 26 is provided with a pressure introduction path 55 communicating with the H.26.
By providing the pressure introduction path 55, the refrigerant sucked into the high stage compression chamber 35 flows into the low stage back pressure chamber 26. That is, the pressure in the low-stage back pressure chamber 26 is the same as the pressure of the suction refrigerant in the high-stage compression unit 30.

Next, the force applied to the low stage vane 13 will be described.
FIG. 13 is an explanatory diagram of the force applied to the low stage vane 13.
In the low stage vane 13, the pressure Pv in the low stage back pressure chamber 26 and the area v where the pressure Pv acts on the low stage vane 13 from the low stage back pressure chamber 26 side toward the low stage compression chamber 15 side. A force (Pv × v) expressed by the product of the above and a force Psp of the spring 27 are applied. That is, a force of “Pv × v + Psp” is applied to the low stage vane 13 from the low stage back pressure chamber 26 side toward the low stage compression chamber 15 side.
On the other hand, in the low stage vane 13, the product of the pressure Ps of the suction refrigerant and the area a of the portion where the pressure Ps acts on the low stage vane 13 from the low stage compression chamber 15 side toward the low stage back pressure chamber 26 side. And the force (Pc × b) represented by the product of the pressure Pc of the discharged refrigerant and the area b of the portion where the pressure Pc acts on the low stage vane 13 is applied. Furthermore, a force x (vane centrifugal force) is applied as the low-stage rolling piston 12 rotates eccentrically from the low-stage compression chamber 15 side toward the low-stage back pressure chamber 26 side. That is, a force of “(Ps × a) + (Pc × b) + x” is applied to the low stage vane 13 from the low stage compression chamber 15 side toward the low stage back pressure chamber 26 side.
That is, a force of Fv = (Pv × v + Psp) − ((Ps × a) + (Pc × b) + x) is applied to the low stage vane 13. Note that area v = area a + area b.

A description will be given of the force applied to the low stage vane 13 when the four-way valve 54 is a flow path indicated by a solid line in FIG.
First, the pressure Pv in the low stage back pressure chamber 26 will be described.
During normal operation, the refrigerant compressed by the low-stage compression unit 10 and discharged into the low-stage discharge space 20 passes through the intermediate connection pipe 51 and the high-stage suction flow path 42 and the high-stage compression chamber 35 of the high-stage compression unit 30. Inhaled. When the refrigerant passes through the high stage suction flow path 42, a part of the refrigerant flows from the pressure introduction path 55 into the low stage back pressure chamber 26. Therefore, the intermediate-pressure refrigerant compressed by the low-stage compression unit 10 flows into the low-stage back pressure chamber 26. To be precise, the pressure Pv of the refrigerant in the low-stage back pressure chamber 26 is not the intermediate pressure discharged from the low-stage compression unit 10, but passes through the intermediate connection pipe 51 to reduce the resistance of the intermediate connection pipe 51. The pressure is increased to the intermediate pressure by the amount. That is, the pressure Pv of the refrigerant in the low stage back pressure chamber 26 is slightly higher than the intermediate pressure.
Next, the pressure in the low-stage compression chamber 15 will be described.
During normal operation, the low-stage compressor 10 compresses low-pressure refrigerant to an intermediate pressure. That is, the pressure Ps of the suction refrigerant is low, and the pressure Pc of the discharge refrigerant is an intermediate pressure.
That is, during normal operation, the pressure Pv in the low-stage back pressure chamber 26 (pressure slightly higher than the intermediate pressure) is higher than the pressure Ps (low pressure) and pressure Pc (intermediate pressure) in the low-stage compression chamber 15.

The force applied to the low stage vane 13 when the four-way valve 54 is a flow path indicated by a broken line in FIG. 11 (when the low stage compression unit 10 is bypassed) will be described.
First, the pressure Pv in the low stage back pressure chamber 26 will be described.
When the low-stage compression unit 10 is bypassed, the refrigerant flowing into the suction muffler 7 bypasses the low-stage compression unit 10 and performs high-stage compression via the intermediate connection pipe 51 and the high-stage suction flow path 42. Inhaled into chamber 35. When the refrigerant passes through the high stage suction flow path 42, a part of the refrigerant flows from the pressure introduction path 55 into the low stage back pressure chamber 26. Therefore, the low-pressure refrigerant that has flowed into the suction muffler 7 flows into the low-stage back pressure chamber 26. That is, the pressure Pv in the low stage back pressure chamber 26 is low.
Next, the pressure in the low-stage compression chamber 15 will be described.
When the low-stage compression unit 10 is bypassed, the low-stage compression unit 10 does not suck the refrigerant from the suction muffler 7, and the refrigerant in the low-stage compression unit 10 passes through the low-stage compression chamber 15 and the low-stage discharge space 20. It is the refrigerant which circulates. Therefore, the same refrigerant is repeatedly compressed by the low stage compression unit 10. However, the refrigerant having a pressure higher than the discharge pressure is discharged from the bypass port 23 to the discharge pressure space 53. Therefore, the pressure in the low-stage compression chamber 15 changes from a low pressure to a discharge pressure.
That is, when the low-stage compression unit 10 is bypassed, the pressure Pv (low pressure) in the low-stage back pressure chamber 26 is equal to or lower than the pressure Ps and the pressure Pc in the low-stage compression chamber 15. Although the pressure Pv in the low-stage back pressure chamber 26 may temporarily be equivalent to the pressure in the low-stage compression chamber 15, the pressure Pv in the low-stage back pressure chamber 26 is immediately lower. It becomes lower than the pressure in the stage compression chamber 15.

Therefore, by adjusting the force Psp of the spring 27 and the vane centrifugal force x, the force Fv applied to the low-stage vane 13 becomes larger than 0 during normal operation, and the low-stage compression unit 10 is low when bypassed. The force Fv applied to the stage vane 13 can be made smaller than zero. That is, during normal operation, the force applied to the low stage vane 13 from the low stage back pressure chamber 26 side to the low stage compression chamber 15 side is directed from the low stage compression chamber 15 side to the low stage back pressure chamber 26 side. It should be greater than this force. On the other hand, when the low-stage compression unit 10 is bypassed, the force applied to the low-stage vane 13 from the low-stage back pressure chamber 26 side to the low-stage compression chamber 15 side is low from the low-stage compression chamber 15 side. The force is made smaller than the force applied toward the step back pressure chamber 26 side.
By setting in this way, the low stage vane 13 is pressed against the low stage rolling piston 12 during normal operation. That is, the low-stage vane 13 has high followability with respect to the revolution of the low-stage rolling piston 12. On the other hand, when the low stage compression unit 10 is bypassed, the low stage vane 13 is hardly pressed against the low stage rolling piston 12. That is, the friction loss between the low stage vane 13 and the low stage rolling piston 12 is reduced.

  Since the friction loss between the low-stage vane 13 and the low-stage rolling piston 12 is reduced, the heat pump device 101 including the two-stage compressor 100 according to the third embodiment has better efficiency when the load is very low. Can do.

Embodiment 4 FIG.
In the fourth embodiment, a two-stage compressor 100 that controls the generated torque in accordance with the required torque will be described.

FIG. 14 is a diagram showing torque fluctuation of a normal twin rotary compressor. The twin rotary compressor is a compressor in which two compression units operate in parallel.
FIG. 15 is a diagram illustrating torque fluctuation when the two-stage compressor 100 according to Embodiment 1 is normally operated. The normal operation is an operation in which the refrigerant is sucked from the suction muffler 7 to the low-stage compression unit 10 and the bypass valve 24 is closed and the refrigerant is not discharged from the bypass port 23.
FIG. 16 is a diagram showing torque fluctuations when the two-stage compressor 100 according to Embodiment 1 is subjected to an overcompression relief operation. The overcompression relief operation is an operation in which the refrigerant is sucked from the suction muffler 7 to the low-stage compression unit 10 and the refrigerant is discharged from the bypass port 23 by operating the bypass mechanism.
FIG. 17 is a diagram showing torque fluctuations when the two-stage compressor 100 according to the second embodiment is in the high-stage direct suction operation. The high-stage direct suction operation is an operation in which the four-way valve 54 is switched to the broken-line flow path in FIG. 11 and sucked from the suction muffler 7 to the high-stage compression unit 30.

  As shown in FIGS. 14 to 17, in the two-stage compressor, fluctuations in rotational torque accompanying changes in the crank angle of the crankshaft 4 are greater than in the twin rotary compressor. When the fluctuation of the rotational torque accompanying the change of the crank angle is large, the efficiency of the electric motor is lowered and the vibration is increased. In particular, a reduction in the efficiency of the motor due to a large rotational torque fluctuation accompanying a change in the crank angle has a large effect on the efficiency when the motor is operated at a low rotational speed, that is, when the load is small. Further, when the vibration becomes large, noise is caused and the reliability of the piping of the heat pump device is reduced.

In the twin rotary compressor, the two compression parts having the same compression chamber volume are arranged with the eccentric phase of the rolling piston shifted by 180 degrees, so the torques cancel each other out. Therefore, as shown in FIG. 14, in the twin rotary compressor, the torque fluctuation accompanying the change in the crank angle is small.
On the other hand, in the two-stage compressor 100, as described in the first embodiment, the compression chamber volume of the high-stage compression unit 30 is smaller than the compression chamber volume of the low-stage compression unit 10. That is, there is a difference in the compression work between the low-stage compression unit 10 and the high-stage compression unit 30. Therefore, as shown in FIG. 15, the two-stage compressor 100 has a larger rotational torque fluctuation due to the change in the crank angle than the twin rotary compressor. In particular, the rotational torque varies greatly between the timing at which the refrigerant is discharged from the low stage compression chamber 15 to the low stage discharge space 20 and the timing at which the refrigerant is discharged from the high stage compression chamber 35 to the high stage discharge space 40.
Further, as shown in FIG. 16, when the overcompression relief operation is performed, the rotational torque fluctuation accompanying the change of the crank angle becomes slightly larger than that in the normal operation shown in FIG. This is because the compression is mainly performed only by the low-stage compression unit 10, and thus the behavior is similar to that of a single rotary compressor having only one compression unit. That is, there is almost no torque cancellation between the two compression sections.
Further, as shown in FIG. 17, when the high-stage direct suction operation is performed, the behavior is similar to that of the single rotary compressor as in the case of the overcompression relief operation shown in FIG. growing.

Therefore, in the two-stage compressor 100, the control unit controls the electric motor 2 so that the torque (output torque) is generated in accordance with the necessary torque that is the torque necessary for operation (load torque). Thereby, torque fluctuation is suppressed small. Here, the necessary torque can be determined from, for example, the rotational speed of the compressor, a change in current, a change in vibration, a crank angle, and the like.
For example, the control unit determines the necessary torque from the rotation speed of the compressor and the crank angle. For example, the control unit stores in advance a table in which necessary torque is recorded for each rotation speed and crank angle of the compressor in a memory. During operation, the control unit detects the rotational speed and the crank angle of the compressor, and reads out the necessary torque corresponding to the detected rotational speed and crank angle of the compressor from the memory. And a control part controls the electric motor 2 so that the read required torque may generate | occur | produce. Further, learning control for learning necessary torque corresponding to various indexes such as the rotational speed of the compressor and crank angle may be performed during operation, and torque control may be performed according to the learned result.

  By suppressing the torque fluctuation to be small, the efficiency of the compressor can be further increased and vibration can be reduced.

The above is summarized as follows.
The two-stage compressor 100 is a rotary two-stage compressor in which the low-stage compression unit 10 is disposed on the upper side and the high-stage compression unit 30 is disposed on the lower side, and the low-stage discharge space 20 of the low-stage compression unit 10 is configured as a low-stage compressor. The cover 19 is provided with a bypass port 23 and a bypass valve 24 communicating with the discharge pressure space 53.

  Further, the two-stage compressor 100 includes a suction pipe connected to the suction muffler 7, a suction pipe of the low-stage compression section 10, a discharge pipe of the low-stage compression section 10, and a suction pipe of the high-stage compression section 30. 54, the suction pipe connected to the suction muffler 7 and the suction pipe of the high stage compression section 30 are communicated, and the suction refrigerant gas is directly sucked into the high stage compression section 30 without passing through the low stage compression section 10. It is characterized by comprising.

  Further, the two-stage compressor 100 is characterized in that the suction pressure of the high-stage compression section 30 is communicated with the low-stage back pressure chamber 26 of the low-stage compression section 10.

  Furthermore, the two-stage compressor 100 is characterized in that it performs torque control in accordance with fluctuations in rotational torque.

  DESCRIPTION OF SYMBOLS 1 Airtight container, 2 Electric motor, 2a Stator, 2b Rotor, 3 Compression mechanism part, 4 Crankshaft, 5 Discharge pipe, 6 Lubricating oil storage part, 7 Intake muffler, 8 Intake pipe, 10 Low stage compression part, 11 Low Stage cylinder, 12 Low stage rolling piston, 13 Low stage vane, 14 Low stage frame, 15 Low stage compression chamber, 16 Low stage discharge port, 17 Low stage discharge valve, 18 Low stage valve presser, 19 Low stage cover, 20 Low Stage discharge space, 21 Low stage suction port, 22 Intermediate outlet, 23 Bypass port, 24 Bypass valve, 25 Bypass valve presser, 26 Low stage back pressure chamber, 27 Spring, 28, 29 Rivet, 30 High stage compression section, 31 High stage cylinder, 32 High stage rolling piston, 33 High stage vane, 34 High stage frame, 35 High stage compression chamber, 36 High stage discharge port, 37 High stage discharge valve, 38 High stage valve presser, 3 9 High-stage cover, 40 High-stage discharge space, 41 High-stage suction port, 42 High-stage suction flow path, 46 High-stage back pressure chamber, 50 Intermediate partition plate, 51 Intermediate connection pipe, 52 Discharge flow path, 53 Discharge pressure space 54 Four-way valve, 55 Pressure introduction path, 60 Injector, 61 Injection pipe, 71 Heat exchanger, 72 First expansion valve, 73 Internal heat exchanger, 74 Third expansion valve, 75 Second expansion valve, 76 Heat exchanger 77 Four-way valve, 78 Receiver, 100 Two-stage compressor, 101 Heat pump device.

Claims (14)

A main refrigerant circuit in which a compressor, a first heat exchanger, a first expansion mechanism, and a second heat exchanger are sequentially connected by piping;
The compressor is
A low-stage compression section that compresses the refrigerant sucked into the compression chamber from the main refrigerant circuit and discharges the refrigerant from the discharge port;
A low-stage discharge unit provided on the upper side of the low-stage compression unit, the low-stage discharge unit forming a discharge space in which the refrigerant compressed by the low-stage compression unit is discharged from the discharge port;
An intermediate connecting pipe having one end connected to the discharge space formed by the low-stage discharge unit;
A high-stage compression section provided below the low-stage compression section, the other end of the intermediate connection pipe being connected, and the refrigerant discharged into the discharge space being sucked into the compression chamber from the intermediate connection pipe A high-stage compression section that compresses
An internal space that houses the low-stage compression section, the high-stage compression section, and the low-stage discharge section, and includes a sealed container that forms an internal space in which the refrigerant compressed by the high-stage compression section is discharged. ,
The low-stage discharge part is formed with a bypass port that connects the discharge space and the internal space of the sealed container, and in the first heat exchanger, the low-stage discharge part is configured to exchange heat with the refrigerant flowing through the main refrigerant circuit. The bypass port is provided with an on-off valve that opens when the required load, which is the amount of heat necessary to bring the temperature to a predetermined temperature, is lower than the first load set in advance,
When the necessary load is higher than the first load, the refrigerant compressed by the low-stage compression unit and the high-stage compression unit is discharged to the main refrigerant circuit, and the necessary load is the first load. The heat pump device, wherein the refrigerant compressed by the low-stage compression unit is bypassed and discharged to the main refrigerant circuit without being compressed by the high-stage compression unit . The heat pump device further includes:
Said main from between the first heat exchanger the first expansion mechanism in the refrigerant circuit, an intermediate flow path connecting said in the compressor and low-stage compressing section and the high-stage compressing section, the low-stage An injection circuit in which a pipe is connected to an injection pipe connected to an intermediate flow path formed by a discharge portion and the intermediate connecting pipe, and a second expansion mechanism is provided in the middle of the pipe;
When the required load is higher than the second load set higher than the first load, the opening of the second expansion mechanism provided in the injection circuit is widened to a predetermined opening or more. The main refrigerant circuit is controlled so that a part of the refrigerant flowing from the first heat exchanger toward the expansion mechanism is injected from the injection pipe into the intermediate flow path of the compressor via the injection circuit. The heat pump device according to claim 1, further comprising a control unit. The compressor further includes:
When the required load is lower than the third load set lower than the first load, bypass the refrigerant flowing from the main refrigerant circuit without compressing the low-stage compression unit, The heat pump apparatus according to claim 1, further comprising a switching unit that causes the high-stage compression unit to inhale. A low-stage compression section that compresses the refrigerant sucked into the compression chamber from the suction port and discharges the refrigerant from the discharge port;
A low-stage discharge unit provided on the upper side of the low-stage compression unit, the low-stage discharge unit forming a discharge space in which the refrigerant compressed by the low-stage compression unit is discharged from the discharge port;
An intermediate connecting pipe having one end connected to the discharge space formed by the low-stage discharge unit;
A high-stage compression section provided below the low-stage compression section, the other end of the intermediate connection pipe being connected, and the refrigerant discharged into the discharge space being sucked into the compression chamber from the intermediate connection pipe A high-stage compression section that compresses
An internal space that houses the low-stage compression section, the high-stage compression section, and the low-stage discharge section, and includes a sealed container that forms an internal space in which the refrigerant compressed by the high-stage compression section is discharged. ,
The low-stage discharge portion is formed when a bypass port that connects the discharge space and the internal space of the sealed container is formed and the pressure of the refrigerant in the discharge space is higher than the pressure of the refrigerant in the internal space. A two-stage compressor comprising an on-off valve at the bypass port. The discharge port of the low-stage compression unit is provided with an on-off valve that opens when the pressure of the refrigerant in the compression chamber of the low-stage compression unit becomes higher than the pressure of the refrigerant in the discharge space,
Wherein the low-stage compressing section of the discharge port provided opening and closing valve, according the to claim 4 is the low-stage discharge portion of the bypass port is provided opening and closing valve, characterized in that the same structure two Stage compressor. The on-off valve provided in the discharge port of the low-stage compressing section, said the low-stage discharge portion of the provided in the bypass opening and closing valve, in claim 5, characterized in that both a reed valve The two-stage compressor described. The two-stage compressor further includes:
A suction muffler into which refrigerant flows from the outside;
A suction pipe connecting the suction muffler and the suction port of the low-stage compression unit;
A flow path through which the refrigerant flowing into the suction muffler is sucked from the suction port to the low-stage compression section through the suction pipe, and a middle part of the suction pipe and a middle part of the intermediate connecting pipe are connected; A switching unit that bypasses the refrigerant flowing into the suction muffler without being compressed by the low-stage compression unit and selectively switches the flow path to be sucked into the high-stage compression unit. 4. The two-stage compressor according to 4 . The switching unit connects the suction muffler and the suction port of the low-stage compression unit through the suction pipe, and connects the low-stage discharge unit and the suction port of the high-stage compression unit through the intermediate connection pipe. A flow path that connects the middle of the suction pipe and the middle of the intermediate connecting pipe to connect the suction muffler and the suction port of the high-stage compression section, and the low-stage discharge section and the low-stage The two-stage compressor according to claim 7 , wherein the flow path connecting the suction port of the compression unit is selectively switched. The two-stage compressor according to claim 7 , wherein the high-stage compression section has a compression chamber volume smaller than that of the low-stage compression section. The low-stage compression unit is
Back pressure chamber,
A vane that is pressed by the pressure inside the back pressure chamber and protrudes toward the compression chamber, and divides the compression chamber into a space on the suction port side and a space on the discharge port side;
The two-stage compressor further includes:
5. The two-stage compression according to claim 4 , further comprising an inflow path through which a part of the refrigerant sucked into the compression chamber of the high-stage compression section flows into the back pressure chamber included in the low-stage compression section. Machine. The two-stage compressor further includes:
An electric motor for operating the low-stage compression unit and the high-stage compression unit;
And a control unit that controls the operation of the electric motor so that the required torque is generated by the electric motor in accordance with the necessary torque required to operate the low-stage compression unit and the high-stage compression unit. The two-stage compressor according to claim 4 . The two-stage compressor further includes:
An injection pipe connected to an intermediate flow path connecting the low-stage compression section and the high-stage compression section and formed by the low-stage discharge section and the intermediate connection pipe
The two-stage compressor according to claim 4, comprising: A main refrigerant in which a two-stage compressor in which a low-stage compressor and a high-stage compressor are connected in series, a first heat exchanger, a first expansion mechanism, and a second heat exchanger are sequentially connected by piping. It is an operation method of a heat pump device including a circuit,
In the first heat exchanger, a required load that is an amount of heat necessary to bring the temperature of the fluid that exchanges heat with the refrigerant flowing through the main refrigerant circuit to a predetermined temperature is higher than the preset first load. In this case, the refrigerant compressed by the low-stage compression unit and the high-stage compression unit is discharged to the main refrigerant circuit,
Wherein when required load is lower than said first load, and discharge the bypassing without the low-stage compression section for compressing the refrigerant compressed in the high stage compression portion to the main refrigerant circuit,
When the required load is lower than the third load set lower than the first load, bypass the refrigerant flowing from the main refrigerant circuit without compressing the low-stage compression unit, The operation method of the heat pump apparatus, wherein the high-stage compression section having a compression chamber volume smaller than the low-stage compression section is sucked . The heat pump device further includes:
From between the first heat exchanger in the main refrigerant circuit and the first expansion mechanism to an injection pipe connected to an intermediate flow path connecting the low-stage compression section and the high-stage compression section in the compressor Equipped with an injection circuit
The operation method of the heat pump device further includes:
When the required load is higher than the second load set higher than the first load, a part of the refrigerant flowing through the main refrigerant circuit from the first heat exchanger toward the expansion mechanism is removed. The operation method of the heat pump device according to claim 13, wherein injection is performed from the injection circuit to the intermediate flow path.

Images