Heat pump water heater

Abstract

To provide a heat pump water heater mounted with a twin rotary compressor which can install a muffler to the twin rotary compressor by retrofitting by integrally unitizing the muffler, and can prevent an operation failure of a vane at the activation of the twin rotary compressor, or can shorten a generation time of the operation failure of the vane.SOLUTION: In a heat pump water heater which uses a twin rotary compressor with a carbon dioxide as a refrigerant at a single-stage compression cycle, a muffler is connected to a discharge port of the refrigerant of the twin rotary compressor in order to suppress vibration which is generated at the compression of the refrigerant by the twin rotary compressor, and the twin rotary compressor and the muffler are integrally connected to each other, and unitized.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a heat pump water heater, and more particularly to a heat pump water heater equipped with a twin rotary compressor. [Background technology]

[0002] Conventionally, twin rotary compressors using carbon dioxide as a refrigerant have been used as refrigeration equipment for showcases and the like. In this case, it has been technically established to use the twin rotary compressor in a general two-stage compression refrigeration cycle. When such a twin rotary compressor using carbon dioxide as a refrigerant is used in a heat pump water heater for a public bath or spa that requires a large amount of hot water, the refrigerant needs to be made into a high-pressure, high-temperature gas to generate high-temperature water. For this reason, it has been necessary to use the twin rotary compressor in a special way, using it as a single-stage compression refrigeration cycle instead of the general two-stage compression refrigeration cycle.

[0003] In such special usage, the twin rotary compressor itself vibrates strongly, and the vibrations may cause excessive stress on the refrigerant piping that is connected to the twin rotary compressor and circulates the refrigerant between the condenser and the evaporator, damaging the refrigerant piping and causing refrigerant leakage. For this reason, vibration-damping material is installed on the refrigerant piping to prevent the vibrations of the twin rotary compressor from being transmitted to the refrigerant piping. It is also preferable to connect a sound-absorbing device (hereinafter referred to as a muffler) for the driving and vibration noise generated by the twin rotary compressor to the twin rotary compressor.

[0004] In addition, when the twin rotary compressor is started, the vanes used in the rolling pistons malfunction (i.e., the vane flies off). This malfunction causes the twin rotary compressor to vibrate, which in turn transmits to the refrigerant piping connecting the twin rotary compressor to the muffler, damaging the refrigerant piping and causing refrigerant leakage.

[0005] In order to absorb such compressor vibrations, a heat pump water heater has been disclosed in which the legs of the compressor body of the heat pump water heater are fixed with vibration-proof rubber, and a two-layer insulation material made of a flexible insulating material and a highly rigid soundproofing material is tightly wrapped around the compressor body and the periphery of the suction muffler, eliminating gaps in the insulation material and forming an airtight structure, which prevents the vibrations of the compressor from being transmitted to the outside, provides excellent soundproofing, has a large insulating effect, and reduces heat loss from the compressor body, improving efficiency (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-008363 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the heat pump water heater in Patent Document 1 is a small water heater that houses the compressor and refrigerant circuit in the hot water heat source unit (so-called outdoor unit), so there is no space to retrofit a muffler to reduce driving and vibration noise in the compressor.

[0008] Furthermore, in order to generate high-temperature water as a heat pump water heater for use in public baths, spas, and other facilities that require a large amount of hot water, the twin rotary compressor cannot be used in a special manner, such as as a single-stage compression refrigeration cycle instead of the general two-stage compression refrigeration cycle.

[0009] The present invention has been made to solve the above-mentioned problems, and aims to provide a heat pump water heater equipped with a twin rotary compressor which can be retrofitted to the twin rotary compressor as an integrated unit with a muffler, and which can prevent vane malfunction (i.e., vane flying) when the twin rotary compressor is started up, or can shorten the time during which vane malfunction occurs. [Means for solving the problem]

[0010] The present invention provides a heat pump water heater that uses a twin rotary compressor using carbon dioxide as a refrigerant in a single-stage compression refrigeration cycle, in which a muffler is connected to the refrigerant discharge port of the twin rotary compressor in order to suppress vibrations that occur when the refrigerant is compressed by the twin rotary compressor, and the twin rotary compressor and the muffler are connected together to form a unit.

[0011] Furthermore, in order to reduce the pressure of the refrigerant drawn into the compression space in the rotary cylinder when the twin rotary compressor is started, an intermediate flow path for the refrigerant that discharges the refrigerant is provided outside the twin rotary compressor, and a second expansion valve installed in the intermediate flow path is controlled to open and close to reduce the intermediate pressure of the refrigerant inside the twin rotary compressor, thereby preventing malfunction of vanes in the rotary cylinder used during second-stage compression of the refrigerant or shortening the time during which the vane malfunction occurs. Effect of the Invention

[0012] In the heat pump water heater of the present invention, the vibration of the twin rotary compressor itself, which occurs when the twin rotary compressor is used in a single-stage compression refrigeration cycle, can be suppressed as low as possible by connecting the muffler. This makes it possible to prevent the refrigerant piping, which is connected to the twin rotary compressor and circulates the refrigerant between the condenser and the evaporator, from being damaged by excessive stress due to vibration, resulting in refrigerant leakage. Furthermore, by connecting the twin rotary compressor and the muffler as an integral unit, the compressor and the muffler can be synchronized, and the problem of the refrigerant piping connecting the twin rotary compressor and the muffler being damaged by the vibration of the twin rotary compressor, resulting in refrigerant leakage, can be prevented.

[0013] Furthermore, in order to reduce the pressure of the refrigerant drawn into the compression space in the rotary cylinder when the twin rotary compressor is started, an intermediate refrigerant flow path that discharges the refrigerant outside the twin rotary compressor is provided, and the second expansion valve installed in this intermediate flow path is controlled to open and close to reduce the intermediate pressure of the refrigerant inside the twin rotary compressor. This makes it possible to prevent malfunction of the vanes pressed against the outer peripheral surface of the rolling piston in the rotary cylinder used during the second stage compression of the refrigerant (vane jumping) or to shorten the time during which the vane malfunction occurs, and makes it possible to keep vibrations generated in the twin rotary compressor due to vane malfunction as low as possible. [Brief description of the drawings]

[0014] [Figure 1] 1 is a refrigerant circuit diagram of a heat pump water heater according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating a connection between a twin rotary compressor and a muffler according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating a connection between a twin rotary compressor and a muffler according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram illustrating the operation of a rotary cylinder of the twin rotary compressor according to one embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram illustrating the operation of a rotary cylinder of the twin rotary compressor according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention relates to a heat pump water heater that uses a twin rotary compressor using carbon dioxide as a refrigerant in a single-stage compression refrigeration cycle, in which a muffler is connected to the refrigerant discharge port of the twin rotary compressor in order to suppress vibrations that occur when the refrigerant is compressed by the twin rotary compressor, and the twin rotary compressor and the muffler are connected together to form a unit.

[0016] Hereinafter, a heat pump water heater according to an embodiment of the present invention will be specifically described with reference to the drawings. Fig. 1 is a refrigerant circuit diagram of a heat pump water heater according to an embodiment of the present invention. Fig. 2 is a diagram explaining the connection between a twin rotary compressor and a muffler according to an embodiment of the present invention. Fig. 3 is a diagram explaining the connection between a twin rotary compressor and a muffler according to an embodiment of the present invention. Fig. 4 is a diagram explaining the operation of a rotary cylinder of a twin rotary compressor according to an embodiment of the present invention. Fig. 5 is a diagram explaining the operation of a rotary cylinder of a twin rotary compressor according to an embodiment of the present invention.

[0017] As shown in Figure 1, the refrigerant circuit of the heat pump water heater in this embodiment is composed of a refrigerant piping 7 through which a refrigerant (carbon dioxide) circulates, and various devices connected to this refrigerant piping 7 (a twin rotary compressor 2, a muffler 3, a water-side heat exchanger 4 (condenser), an air-side heat exchanger 5 (evaporator), an internal heat exchanger 6, an intermediate flow path 7a, an accumulator 8, a strainer 9, a first expansion valve 10, and a second expansion valve 11).

[0018] In addition, the water-side heat exchanger 4 is disposed so that the hot water supply pipe 12 passes through it. Water passing through the water-side heat exchanger 4 via a flow rate sensor 14 by a pump 13 on the water supply side of the hot water supply pipe 12 is heat exchanged and heated within the water-side heat exchanger 4. The hot water heated here is supplied from the hot water outlet side of the hot water supply pipe 12 as hot water at a predetermined temperature. The flow rate sensor 14 measures the flow rate of water passing through the water-side heat exchanger 4, and by adjusting the output of the pump 13 according to the water flow rate measured here, it is possible to adjust the temperature of the hot water supplied from the hot water outlet side of the hot water supply pipe 12.

[0019] In this embodiment, water is supplied from the water supply side of the hot water supply pipe 12, and the hot water heated in the water side heat exchanger 4 is supplied from the hot water outlet side, but it is also possible to install a hot water storage tank on the hot water outlet side and temporarily store the heated hot water in the hot water storage tank before supplying it from the hot water outlet side.

[0020] The refrigerant (carbon dioxide) compressed to a high temperature and high pressure by the twin rotary compressor 2 is discharged into the muffler 3 which is integrated into a unit with the twin rotary compressor 2. In this embodiment, the twin rotary compressor 2 and the muffler 3 are integrated into a unit by two upper and lower plate-shaped connecting plates 30, 30, which will be described in detail later. The refrigerant that has passed through the muffler 3 circulates through the refrigerant piping 7 and flows into the water-side heat exchanger 4. Then, water that passes through the water-side heat exchanger 4 by the pump 13 on the water supply side of the hot water supply piping 12 is heat exchanged and heated in the water-side heat exchanger 4.

[0021] The refrigerant discharged from the water-side heat exchanger 4 after heat exchange circulates through the refrigerant piping 7, undergoes further heat exchange in the internal heat exchanger 6, and is decompressed by the first expansion valve 10 before flowing into the air-side heat exchanger 5 (evaporator). A strainer 9 installed on the refrigerant piping 7 before the first expansion valve 10 is a filter that filters out dirt and the like from the refrigerant circulating through the refrigerant piping 7. The refrigerant in the refrigerant piping 7 that flows into the air-side heat exchanger 5 by opening the first expansion valve 10 absorbs heat from the outside air blown by the fan F, is evaporated and gasified, circulates through the refrigerant piping 7, and flows into the internal heat exchanger 6.

[0022] The refrigerant in the refrigerant pipe 7 is reheated in the internal heat exchanger 6, and the liquefied refrigerant is separated in the accumulator 8, and then supplied again to the twin rotary compressor 2. In the internal heat exchanger 6, heat is exchanged between the refrigerant flowing through the refrigerant pipe 7 from the outlet of the air-side heat exchanger 5 (evaporator) to the twin rotary compressor 2 and the refrigerant flowing through the refrigerant pipe 7 from the outlet of the water-side heat exchanger 4 to the air-side heat exchanger 5. The flow rate of the refrigerant flowing from the outlet of the water-side heat exchanger 4 to the internal heat exchanger 6 is adjusted to a required flow rate by the capillary tube 15. This capillary tube 15 is a copper capillary tube with an inner diameter of about 0.7 to 2.5, and is a type of expansion valve that does not fluctuate in condensation pressure or evaporation pressure and passes a required flow rate of refrigerant depending on the pressure difference before and after.

[0023] As described above, in the refrigerant circuit of the heat pump water heater in this embodiment, the refrigerant circulating through the refrigerant piping 7 is compressed to high temperature and pressure by the twin rotary compressor 2 and supplied to the water-side heat exchanger 4, where it exchanges heat with water passing through the hot water supply piping 12, thereby supplying hot water at a predetermined temperature.

[0024] In addition, an intermediate flow path 7a for the refrigerant is connected to the twin rotary compressor 2. This intermediate flow path 7a can reduce the pressure of the refrigerant inside the twin rotary compressor 2 by opening a second expansion valve 11 provided in the intermediate flow path 7a and allowing the refrigerant to flow from the refrigerant pipe 7 to the air-side heat exchanger 5 via the intermediate flow path 7a. This is a configuration for reducing the pressure of the refrigerant supplied to the rotary cylinder used during the second stage compression of the twin rotary compressor 2 to eliminate malfunction of the vanes, as will be described in detail later. In addition, a strainer 9 provided before the second expansion valve 11 of the intermediate flow path 7a has a function of filtering out dust and the like from the refrigerant passing through the intermediate flow path 7a.

[0025] Hereinafter, with reference to Figs. 2 and 3, a description will be given of two upper and lower plate-shaped connecting plates 30, 30 which integrally connect the twin rotary compressor 2 and the muffler 3 in this embodiment to form a unit.

[0026] As shown in Fig. 2 and Fig. 3, the twin rotary compressor 2 is placed on the upper part of a base K having a vibration prevention function at the lower part. The twin rotary compressor 2 and the muffler 3 are connected together at two upper and lower parts horizontally and parallel to each other by two connecting plates 30, 30 to form a unit. The connecting plate 30 is formed as a flat plate having an internal space shaped like glasses in a plan view, and is divided into three parts: a left outer peripheral clamping plate 30a that contacts the left half of the outer peripheral surface of the twin rotary compressor 2, a middle outer peripheral clamping plate 30b that contacts the right half of the outer peripheral surface of the twin rotary compressor 2 and the left half of the outer peripheral surface of the muffler 3, and a right outer peripheral clamping plate 30c that contacts the right half of the outer peripheral surface of the muffler 3.

[0027] The right end of the left outer peripheral clamping plate 30a and the left end of the corresponding central outer peripheral clamping plate 30b are horizontally opposed to each other. Direction A connecting portion 30A having a bolt insertion hole is provided, and by inserting a bolt B into this bolt insertion hole and fastening it with a nut N, the outer peripheral surface of the twin rotary compressor 2 is clamped by the left outer peripheral clamping plate 30a and the middle outer peripheral clamping plate 30b.

[0028] The right end of the central outer peripheral clamping plate 30b and the left end of the corresponding right outer peripheral clamping plate 30c are horizontally opposed to each other. Direction A connecting portion 30B having a bolt insertion hole is provided, and by inserting a bolt B into this bolt insertion hole and fastening it with a nut N, the outer peripheral surface of the muffler 3 is clamped between the middle outer peripheral clamping plate 30b and the right outer peripheral clamping plate 30c.

[0029] A steel plate of a predetermined thickness is preferably used as the material for the connecting plates 30, 30, but it is desirable to attach a cushioning material such as hard rubber to the contact surface of the connecting plate 30 with the outer circumferential surface of the twin rotary compressor 2 and the contact surface with the outer circumferential surface of the muffler 3. This makes it possible to attach the connecting plate 30 by clamping it without damaging the outer circumferential surfaces of the twin rotary compressor 2 and the muffler 3, even if the joints 30A, 30B are fastened tightly with the bolts B and nuts N.

[0030] In this way, the twin rotary compressor 2 is placed on top of a base K equipped with a vibration prevention function at the bottom, and the high-pressure refrigerant discharged from the twin rotary compressor 2 is circulated through the refrigerant piping 7 (see FIG. 1) via the muffler 3. As a result, the high vibration of the compressor itself, which occurs when the twin rotary compressor 2 is used in a single-stage compression refrigeration cycle, can be suppressed as low as possible by connecting the muffler 3.

[0031] Furthermore, since it is possible to prevent vibrations from the twin rotary compressor 2 from reaching the refrigerant piping 7 (see FIG. 1), there is no need to install vibration-damping materials or the like that are required in conventional equipment to suppress vibrations in the refrigerant piping 7 to which multiple devices are connected. Furthermore, since the muffler 3 can be retrofitted to the twin rotary compressor 2, the muffler 3 can also be installed retrofit in equipment that uses an existing twin rotary compressor 2 in a single-stage compression refrigeration cycle.

[0032] Furthermore, by connecting the twin rotary compressor 2 and the muffler 3 together as a unit using two connecting plates 30, 30 at the top and bottom, the vibrations of the twin rotary compressor 2 and the muffler 3 can be synchronized, preventing the problem of refrigerant leakage caused by damage to the connection part of the refrigerant piping 7 connecting the twin rotary compressor 2 and the muffler 3 due to the vibration of the twin rotary compressor 2.

[0033] Hereinafter, the configuration and operation of the rotary cylinder 20, which is a compression section that compresses the refrigerant (carbon dioxide) to a high pressure and is provided inside the twin rotary compressor 2 of this embodiment, will be described with reference to Figures 4 and 5. Figures 4 and 5 are horizontal cross-sectional views of the rolling piston type rotary cylinder 20.

[0034] The twin rotary compressor 2 includes upper and lower two-stage rotary cylinders 20. The refrigerant compressed in the first-stage rotary cylinder 20 is further compressed to a higher pressure in the second-stage rotary cylinder 20. The first-stage rotary cylinder 20 and the second-stage rotary cylinder 20 have the same basic configuration.

[0035] 4 and 5, a refrigerant compression space 25, closed at the top and bottom, is formed in the center of the rolling piston type rotary cylinder 20. A rolling piston 22 is eccentrically supported by the drive shaft 21 in the compression space 25 so as to be rotatable horizontally. A vane 27 is inserted into the vane sliding portion 26 so that its tip abuts against the outer periphery of the rolling piston 22 and its rear end is slidably pressed against the rolling piston 22 by the discharge pressure of the refrigerant.

[0036] One end of the drive shaft 21 is connected to an electric motor (not shown), and the rotation of the drive shaft 21 (clockwise in the figure) causes the rolling piston 22 to rotate eccentrically horizontally clockwise within the compression space 25. The rotary cylinder 20 is provided with a refrigerant intake port 23 and a discharge port 24. The refrigerant sucked into the compression space 25 from the intake port 23 changes the volume of the compression space 25 due to the eccentric rotation of the rolling piston 22, and is compressed to a predetermined pressure, and then discharged from the discharge port 24 to the outside of the rotary cylinder 20.

[0037] The discharge port 24 is closed by a discharge valve 28. This discharge valve 28 keeps the discharge port 24 closed until the refrigerant in the compression space 25 reaches a predetermined pressure, and when the refrigerant in the compression space 25 reaches or exceeds the predetermined pressure, the discharge valve 28 automatically opens the discharge port 24 as shown in FIG.

[0038] The pressure in the second-stage rotary cylinder 20 varies between the intermediate pressure and the high pressure, and the average is between the intermediate pressure and the high pressure. In other words, during normal operation, the discharge pressure pressing the vane 27 from the back is higher than the pressure in the second-stage rotary cylinder 20. Therefore, during normal operation, the pressure on the back of the vane 27 presses the vane 27 against the outer circumferential surface of the rolling piston 22, and the vane 27 can be kept pressed against the outer circumferential surface of the rolling piston 22.

[0039] However, when the twin rotary compressor 2 is started, the pressure of the refrigerant drawn into the compression space 25 from the suction port 23 may be higher than the discharge pressure pressing the vane 27 from the back side. In such a situation, it becomes difficult to keep the vane 27 pressed against the outer circumferential surface of the rolling piston 22, causing a malfunction of the vane 27 known as vane jumping.

[0040] When the vane jump occurs, the suction and compression of the refrigerant in the compression space 25 becomes incomplete, and the refrigerant is not compressed to a predetermined pressure in the second-stage rotary cylinder 20. In this case, the vane 27 may break off from the outer circumferential surface of the rolling piston 22 and repeatedly collide with the rolling piston 22, resulting in a chattering phenomenon. This may lead to damage to the vane 27 or the rolling piston 22, and increased vibration and noise of the twin rotary compressor 2.

[0041] In order to prevent this, in this embodiment, as shown in Fig. 1, an intermediate flow path 7a for the refrigerant is connected to the twin rotary compressor 2. This intermediate flow path 7a allows the refrigerant to flow into the air-side heat exchanger 5 by opening a second expansion valve 11 provided in the intermediate flow path 7a, and reduces the pressure of the refrigerant inside the twin rotary compressor 2. As a result, the pressure of the refrigerant supplied to the rotary cylinder 20 used during the second stage compression is reduced, and the tip of the vane 27 can be brought into contact with the outer circumferential surface of the rolling piston 22 by the discharge pressure of the rotary cylinder 20 used during the second stage compression, and thus it is possible to prevent malfunction of the vane 27 (vane jumping) or shorten the time of malfunction.

[0042] In this case, the opening angle and opening time for opening and closing the second expansion valve 11 are controlled by a control unit (not shown). As an example, the second expansion valve 11 of the intermediate flow passage 7a connected to the twin rotary compressor 2 is controlled to open to a maximum angle (e.g., 300 degrees) during a predetermined opening time (e.g., 35 seconds) and then closed stepwise by a predetermined angle (50 degrees). The second expansion valve 11 is opened and closed by this control unit twice when the twin rotary compressor 2 is started up. This is based on the verification result that, according to an experiment conducted by the applicant of the present application, if the second expansion valve 11 is opened and closed once, it is insufficient to resolve the malfunction (vane jump) of the vane 27 or to shorten the time of the malfunction.

[0043] As described above, in the heat pump water heater of this embodiment, the vibration of the twin rotary compressor 2 itself, which occurs when the twin rotary compressor 2 is used in a single-stage compression refrigeration cycle, can be suppressed as low as possible by connecting the muffler 3. This makes it possible to prevent the refrigerant piping 7, which circulates the refrigerant between the condenser (water-side heat exchanger 4) and the evaporator (air-side heat exchanger 5) that are connected to the twin rotary compressor 2 and form a refrigerant circuit, from being damaged by excessive stress due to vibration, causing refrigerant leakage. Furthermore, by connecting the twin rotary compressor 2 and the muffler 3 as a unit, the twin rotary compressor 2 and the muffler 3 can be synchronized, and the problem of the refrigerant piping 7 connecting the twin rotary compressor 2 and the muffler 3 being damaged by the vibration of the twin rotary compressor 2 and causing refrigerant leakage can be prevented.

[0044] Furthermore, in order to reduce the pressure of the refrigerant sucked into the compression space 25 in the rotary cylinder 20 when the twin rotary compressor 2 is started, an intermediate flow path 7a for the refrigerant that discharges the refrigerant is provided outside the twin rotary compressor 2, and the second expansion valve 11 installed in the intermediate flow path 7a is controlled to open and close to reduce the intermediate pressure of the refrigerant inside the twin rotary compressor 2, thereby preventing malfunction (vane jump) of the vane 27 pressed against the outer circumferential surface of the rolling piston 22 in the rotary cylinder 20 used in the second stage compression of the refrigerant, or shortening the time during which the vane 27 malfunctions. This makes it possible to keep vibrations generated in the twin rotary compressor 2 due to malfunction of the vane 27 as low as possible.

[0045] An example of an embodiment of the present invention has been described above, but the specific configuration of the present invention is not limited to the above embodiment, and design changes and the like that do not deviate from the gist of the invention are also included in the present invention. [Explanation of symbols]

[0046] 1. Heat pump water heater 2 Twin rotary compressor 3. Muffler 4 Water side heat exchanger (condenser) 5 Air side heat exchanger (evaporator) 6 Internal heat exchanger 7 Refrigerant piping 8 Accumulator 9 Strainer 10 First expansion valve 11 Second expansion valve 12 Hot water piping 13. Pump 14 Flow Sensor 15 Capillary Tube 20 Rotary Cylinder 21 Drive shaft 22 Rolling Piston 23 Intake port 24 Outlet 25 Compressed Space 26 Vane sliding part 27 Vane 28 Discharge valve 30 Connecting plate B Bolt N Nut F Fan K base

Claims

1. A heat pump water heater using a twin rotary compressor that compresses a refrigerant in a single-stage compression refrigeration cycle, In order to suppress vibrations that occur when the refrigerant is compressed by the twin rotary compressor, a muffler is connected to the refrigerant discharge port of the twin rotary compressor, and the twin rotary compressor and the muffler are connected to each other by a connector to form a unit; The linker is a first clamping body that contacts one half of a right or left side of an outer circumferential surface of the twin rotary compressor; a second clamping body that contacts the other left and right half circumference of an outer circumferential surface of the twin rotary compressor and the other left and right half circumference of an outer circumferential surface of the muffler and clamps the twin rotary compressor together with the first clamping body; a third clamping body that contacts the other half of the left and right sides of the outer circumferential surface of the muffler and clamps the muffler together with the second clamping body. A heat pump water heater characterized by the above.

2. 2. The heat pump water heater according to claim 1, characterized in that, in order to reduce the pressure of the refrigerant drawn into the compression space in the rotary cylinder when the twin rotary compressor is started, an intermediate refrigerant flow path that discharges the refrigerant outside the twin rotary compressor is provided, and a second expansion valve installed in the intermediate flow path is controlled to open and close to reduce the intermediate pressure of the refrigerant inside the twin rotary compressor, thereby preventing malfunction of vanes in the rotary cylinder used during second-stage compression of the refrigerant or shortening the time during which the vane malfunction occurs.

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