JP2012063111A - Refrigerating cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve COP of a refrigerating cycle device even under a condition that an energy recovery amount is reduced, in a constitution where a pressure-reduced refrigerant is sucked to an expander.SOLUTION: This refrigerating cycle device 1A includes a refrigerant circuit 4 including a compressor 21, a radiator 22, a first pressure reducer 23, the expander 26 and an evaporator 27. A first bypass pathway 5 branched from a radiator downstream pathway 4b or an intermediate-pressure flow channel 4c is connected to an evaporator upstream pathway 4d, and a second bypass pathway 6 branched from the evaporator upstream pathway 4d at an upstream side with respect to a position where the first bypass pathway 6 is connected, is connected to a radiator upstream pathway 4a of the refrigerant circuit 4. Further, this refrigerating cycle device 1A includes a second pressure reducer 51 disposed in the first bypass pathway 5, and a switching means for switching a refrigerant discharged from the expander 26 to the evaporator 27 through the evaporator upstream pathway 4d or the radiator upstream pathway 4a through the second bypass pathway 6.

Description

  The present invention relates to a refrigeration cycle apparatus including an expander that recovers pressure energy in the process of expanding a refrigerant.

  In the refrigeration cycle apparatus, the refrigerant cooled by the radiator is expanded by the expansion means and flows into the evaporator. When an expansion valve is used as the expansion means, the pressure energy of the refrigerant becomes vortex energy, and eventually becomes vibration energy of the refrigerant molecules (isoenthalpy change). One technique for recovering and effectively utilizing the pressure energy of this refrigerant is an expander. The expander recovers the pressure energy as power by smoothly expanding the refrigerant, and generates power by turning the generator, or directly transmits power to the compressor to assist driving the compressor. The refrigeration cycle apparatus can be made highly efficient by reducing the amount.

  For example, Patent Document 1 discloses a refrigeration cycle apparatus 100 as shown in FIG. Moreover, the Mollier diagram which shows the driving | running state of the refrigerating-cycle apparatus 100 is shown in FIG.

  The refrigeration cycle apparatus 100 includes a refrigerant circuit 110 including a compressor 101, an indoor heat exchanger 102, a pre-expansion valve 103, an expander 104, and an outdoor heat exchanger 105. The compressor 101 is driven by a motor 130, and the expander 104 is directly connected to the compressor 101 on one axis so that the recovered power can be directly transmitted to the compressor 921. The refrigerant circuit 110 is provided with four-way valves 111 and 112 for switching between the cooling operation and the heating operation, and a receiver that separates the refrigerant expanded by the pre-expansion valve 103 into a gas phase refrigerant and a liquid phase refrigerant. A tank 120 is provided.

  Points A to E in FIG. 14 indicate the state of the refrigerant at the positions A to E described in FIG. 13. During the heating operation, the refrigerant (point B) discharged from the compressor 101 radiates heat at the indoor heat exchanger 102 (heat radiator) (point C), expands to an intermediate pressure by the pre-expansion valve 103, and then expands. Inhaled by the machine 104 (point D). In the expander 104, the refrigerant is expanded to the internal expansion ratio and discharged (point E). The refrigerant discharged from the expander 104 absorbs atmospheric heat by the outdoor heat exchanger 105 (evaporator), and then is sucked into the compressor 101 again (point A).

JP 2003-74990 A

  However, in the refrigerant circuit 110 described above, the pressure of the refrigerant sucked into the expander 104 decreases as the pressure reduction width at the pre-expansion valve 103 increases, and the power recovery amount of the expander 104 decreases. For example, in a low outside air temperature condition where the refrigerant discharge temperature of the compressor 101 is high, it is necessary to ensure a large difference between the high pressure side refrigerant pressure and the low pressure side refrigerant pressure. For this reason, the pressure reduction width in the pre-expansion valve 103 becomes large, and the COP (Coefficient of Performance) improvement effect of the refrigeration cycle apparatus by the power recovery of the expander 104 is almost lost. In addition, when the pressure reduction width at the pre-expansion valve 103 is large, the flow rate of the refrigerant in the evaporator also decreases, leading to a decrease in the amount of heat absorbed in the evaporator and a decrease in the heating capacity in the radiator. there were.

  The present invention has been made in view of the above problems, and in the configuration in which the decompressed refrigerant is sucked into the expander, the COP of the refrigeration cycle apparatus can be improved even under a condition where the amount of energy recovery is reduced. The purpose is to do.

  In order to achieve the above object, the present invention provides a compressor for compressing a refrigerant, a radiator for cooling the compressed refrigerant, a first decompressor for decompressing the cooled refrigerant, and expanding the decompressed refrigerant to increase power. A refrigerant circuit including an expander to be recovered and an evaporator for heating the expanded refrigerant, a radiator lower flow path between the radiator and the first pressure reducer in the refrigerant circuit, or the first pressure reducer and the expander A first bypass passage provided with a second decompressor for decompressing the refrigerant, branching from the intermediate pressure passage between and connected to the evaporator upper passage between the expander and the evaporator in the refrigerant circuit; A second bypass path branched from the evaporator upper flow path upstream of the position where the first bypass path is connected, and connected to a radiator upper flow path between the compressor and the radiator in the refrigerant circuit; Discharged from the expander Refrigerant, to provide a refrigeration cycle apparatus and a switching means for switching between the leads to the radiator upstream passage through the evaporator upstream said one lead to the evaporator the second bypass passage through passage.

  According to the above configuration, if the refrigerant discharged from the expander by the switching unit is guided to the evaporator through the evaporator upper flow path and the amount of refrigerant flowing through the first bypass path is limited, power is recovered by the expander. can do. Conversely, if the refrigerant discharged from the expander by the switching means is led to the evaporator through the second bypass passage and the amount of refrigerant flowing through the first bypass passage is increased, the expander forces the refrigerant to the high pressure side. Therefore, the expander can function as a compressor. And since the refrigerant | coolant compressed by the expander flows into a heat radiator and the refrigerant | coolant flow rate of a heat radiator increases, the heating capability of a refrigerating-cycle apparatus can be increased. In addition, a part of the refrigerant decompressed by the first decompressor flows into the expander, and the remaining refrigerant passes through the second decompressor and flows into the evaporator, so that the flow rate of the refrigerant pressurized by the compressor And the power required to drive the compressor is reduced. Therefore, even when the pressure of the refrigerant sucked into the expander decreases, the expander can be effectively used and the COP of the refrigeration cycle apparatus can be improved.

1 is a configuration diagram of a circulating hot water supply system using a refrigeration cycle apparatus according to a first embodiment of the present invention. 1 is a longitudinal sectional view of the compression / expansion unit shown in FIG. (A) is a cross-sectional view of the expander along line IIIA-IIIA in FIG. 2, (b) is a cross-sectional view of the expander along line IIIB-IIIB in FIG. Graph showing the relationship between the volume of the working chamber of the expander shown in FIG. 2 and the rotation angle of the shaft Mollier diagram showing the state of power recovery operation in the intermediate period of the refrigeration cycle apparatus according to the first embodiment The Mollier diagram which shows the state of the power recovery driving | operation at the time of the low external temperature of the refrigerating-cycle apparatus which concerns on 1st Embodiment. Mollier diagram showing the state of the heating capacity enhancement operation of the refrigeration cycle apparatus according to the first embodiment. The longitudinal cross-sectional view of the expander in the modification 1 of 1st Embodiment The longitudinal cross-sectional view of the compression-expansion unit in the modification 2 of 1st Embodiment. FIG. 9 is a cross-sectional view of the expander along the line XX in FIG. The block diagram of the circulation type hot water supply system using the refrigerating cycle device concerning a 2nd embodiment of the present invention. Mollier diagram showing the state of the heating capacity enhancement operation of the refrigeration cycle apparatus according to the second embodiment. Configuration diagram of conventional refrigeration cycle equipment Mollier diagram showing the operating state of a conventional refrigeration cycle system

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

<First Embodiment>
FIG. 1 shows a refrigeration cycle apparatus 1A according to the first embodiment of the present invention. This refrigeration cycle apparatus 1 </ b> A constitutes a circulating hot water supply system together with the hot water heating apparatus 9.

1) Overall Configuration The hot water heating device 9 includes a hot water tank 91 for storing hot water, a boiling passage 92 for boiling water, and a heating passage 94 for using the hot water stored in the hot water tank 91. ing. The boiling passage 92 is a passage for returning water to the upper portion of the hot water tank 91 after heating the water extracted from the lower portion of the hot water tank 91 with the radiator 22 to be described later, and having a boiling pump 93. . The heating path 94 is a flow path for circulating the hot water stored in the hot water tank 91 so as to pass through the heater 96 and a medium-temperature water heat exchanger (water-use heat exchanger) 25 described later in this order, and a circulation pump 95. Further, the heating path 94 is provided with an intermediate warm water bypass path 97 that bypasses the intermediate warm water heat exchanger 25. An intermediate warm water flow rate adjustment valve 99 is provided in a portion of the heating path 94 sandwiched between both ends of the intermediate warm water bypass route 97, and a bypass flow rate adjustment valve 98 is provided in the intermediate warm water bypass route 97.

  In the present embodiment, the heat medium used in the hot water heater 9 is water, but the heat medium used in the hot water heater 9 may be an antifreeze such as ethylene glycol. The hot water heating device 9 is a device that includes a hot water tank 91 and supplies hot water as necessary. However, a hot water heating device that does not include the hot water tank 91 and that is constantly circulating can also be used. It is.

  The refrigeration cycle apparatus 1A includes a refrigerant circuit 4 that circulates refrigerant. The refrigeration cycle apparatus 1A is an apparatus having a constant refrigerant flow direction used together with the hot water heating apparatus 9, but the refrigeration cycle apparatus of the present invention is, for example, a reversible operation refrigeration cycle apparatus capable of changing the refrigerant flow direction. May be. Moreover, the use of the refrigerating cycle apparatus of this invention is not limited at all. For example, the refrigeration cycle apparatus of the present invention can be used as a water heater, an air conditioner or the like.

  The refrigerant circuit 4 is filled with a refrigerant such as carbon dioxide or hydrofluorocarbon. When carbon dioxide is used, the difference between high and low pressures in the refrigerant circuit 4 becomes large, and more expansion energy can be recovered. Therefore, carbon dioxide is suitable as a refrigerant for the power recovery type refrigeration cycle apparatus.

  The refrigerant circuit 4 includes a compressor 21, a radiator 22, a pre-expansion valve (first decompressor) 23, an expander 26, and an evaporator 27 connected in this order by flow paths 4a to 4e. In the present embodiment, a gas-liquid separator 24 is provided in the intermediate pressure flow path 4 c between the pre-expansion valve 23 and the expander 26. The intermediate pressure channel 4 c is configured to guide the gas-phase refrigerant separated by the gas-liquid separator 24 to the expander 26. Further, an intermediate temperature water heat exchanger 25 is provided in the intermediate pressure flow path 4 c on the downstream side of the gas-liquid separator 24.

  The gas-liquid separator 24 according to the present embodiment is a type that uses a self-dropping action of a liquid phase by retaining a gas-liquid mixed refrigerant in a space, but the type uses a surface tension or inertial force. It may be anything that uses, and the format does not matter.

  The compressor 21 and the expander 26 are accommodated in the same sealed container 30 and constitute the compression / expansion unit 3. The compressor 21 sucks and compresses the refrigerant, and discharges the compressed refrigerant to the internal space 31 of the sealed container 30. One end of the pipe 41 is connected to the sealed container 30 so as to open to the internal space 31, and the other end of the pipe 41 is connected to the radiator 22. That is, the internal space 31 and the pipe 41 of the sealed container 30 constitute the radiator upper flow path 4 a that guides the refrigerant from the compressor 21 to the radiator 22.

  The radiator 22 cools the refrigerant discharged from the compressor 21 by exchanging heat with water flowing through the boiling passage 92. The pre-expansion valve 23 expands and depressurizes the refrigerant that has flowed out of the radiator 22. The gas-liquid separator 24 separates the refrigerant that has passed through the pre-expansion valve 23 into a gas phase refrigerant and a liquid phase refrigerant. The intermediate temperature water heat exchanger 25 uses the return water after the gas-phase refrigerant separated by the gas-liquid separator 24 is radiated by the heater 96 flowing through the heating path 96 before being sucked into the expander 26. Heat. That is, the intermediate temperature water heat exchanger 25 functions as a heating unit that heats the refrigerant guided to the expander 26 through the intermediate pressure flow path 4c. The expander 26 normally recovers power by expanding the gas-phase refrigerant that has flowed out of the intermediate temperature water heat exchanger 25. The evaporator 27 heats the refrigerant discharged from the expander 26 by exchanging heat with air.

  In addition, the refrigeration cycle apparatus 1A has a first bypass path 5 that branches from the intermediate pressure flow path 4c and connects to the evaporator upper flow path 4d between the expander 26 and the evaporator 27, and a position where the first bypass path 5 connects. A second bypass path 6 is provided that is branched from the evaporator upper flow path 4 d on the upstream side and is connected to the radiator upper flow path 4 a between the compressor 21 and the radiator 22. In the present embodiment, the downstream end of the second bypass passage 61 opens into the sealed container 30.

  The first bypass path 5 is configured to guide the liquid phase refrigerant separated by the gas-liquid separator 24 to the radiator upper flow path 4d. The first bypass passage 5 is provided with a bypass expansion valve (second decompressor) 51 that expands and decompresses the liquid-phase refrigerant.

  The evaporator upper flow path 4d is provided with an on-off valve 42 on the downstream side of the position where the second bypass path 6 branches. The refrigerant flows from the evaporator upper flow path 4d to the second bypass path 6. Is provided, and a check valve 61 that prohibits the circulation of the refrigerant from the radiator upper flow path 4a side is provided. The on-off valve 42 and the check valve 61 are switched to switch whether the refrigerant discharged from the expander 26 is guided to the evaporator 27 through the evaporator upper flow path 4 d or to the radiator upper flow path 4 a through the second bypass path 6. Configure the means.

  Furthermore, the refrigeration cycle apparatus 1A includes an injection path 7 branched from the downstream side of the intermediate-temperature water heat exchanger 25 of the intermediate pressure flow path 4c and connected to an injection port 74 described later, and a controller 8.

  The upstream portion of the injection path 7 is constituted by a pipe 70, and a flow rate adjusting valve 71 is incorporated in the pipe 70. The flow rate adjustment valve 71 functions as an injection valve that permits or prohibits the circulation of the refrigerant through the injection path 7. The flow rate adjusting valve 71 distributes the refrigerant through the injection path 7 when the refrigerant discharged from the expander 26 by at least the on-off valve 42 and the check valve 61 is guided to the radiator upper flow path 4a through the second bypass path 6. It is preferable to be controlled so as to allow

  The controller 8 controls the motor 33 described later and the various valves described above (the pre-expansion valve 23, the bypass expansion valve 51, the on-off valve 42, and the flow rate adjustment valve 71). As the controller 8, a DSP (Digital Signal Processor) including an input / output circuit, an arithmetic circuit, a storage device and the like can be used. The controller 8 is connected to an outside air temperature sensor 81 that detects the outside air temperature.

2) Configuration of Compression / Expansion Unit Next, the compression / expansion unit 3 will be described in detail with reference to FIG.

  In addition to the compressor 21 and the expander 26, a motor 33 that drives the compressor 21 via the shaft 32 is accommodated in the sealed container 30 of the compression / expansion unit 3. The expander 26 is connected to the shaft 32 so that the recovered power can be transmitted to the shaft 32. The axial direction of the shaft 32 is parallel to the vertical direction. The compressor 21 is disposed at the upper part of the sealed container 30, and the expander 26 is disposed at the lower part of the sealed container 30. The motor 33 is disposed between the compressor 21 and the expander 26. The compressor 21, the expander 26 and the motor 33 are connected to each other by the shaft 32. The power recovered by the expander 26 is transmitted to the compressor 21 via the shaft 32. Thereby, the load of the motor 33 is reduced and the COP of the refrigeration cycle apparatus 1A is improved.

  The sealed container 30 has a cylindrical shape whose top and bottom are closed. An oil reservoir 34 is formed at the bottom of the hermetic container 30 with oil for lubricating and sealing the compressor 21 and the expander 26. The expander 26 is immersed in the oil reservoir 34.

  In the present embodiment, the compressor 21 and the expander 26 are both positive displacement fluid mechanisms. Specifically, the compressor 21 is a scroll compressor, and the expander 26 is a two-stage rotary expander. However, the types of the compressor 21 and the expander 26 are not limited, and types such as a rotary type (including a rolling piston type, a swing type, and a sliding vane type) and a scroll type can be appropriately employed.

  The shaft 32 includes a compression shaft 32a and a sub shaft 32b. The compression shaft 32 a extends across the compressor 21 and the motor 33, and the sub shaft 32 b penetrates the expander 26. The compression shaft 32a and the sub shaft 32b are connected to one axis by a connector 32c. Therefore, the rotational speed of the compressor 21 is always equal to the rotational speed of the expander 26. In addition, the compression shaft 32a and the subshaft 32b may be directly fitted without using the coupler 32c. The shaft 32 may be made of a single piece. A gear, a clutch, a torque converter, or the like may be provided between the compression shaft 32a and the sub shaft 32b so that the rotation speed of the compressor 21 and the rotation speed of the expander 26 are different.

  The expander 26 is a two-stage rotary expander as described above, and is stacked in order from the bottom, the lower bearing 19A, the first closing member 16, the first cylinder 12A, the intermediate plate 17, the second cylinder 12B, the second A closing member 18 and an upper bearing 19B are provided. The first piston 11A is in the space surrounded by the first closing member 16, the first cylinder 12A, and the intermediate plate 17, and the second piston is in the space surrounded by the second closing member 18, the second cylinder 12B, and the intermediate plate 17. Piston 11B is arrange | positioned, respectively. A first eccentric portion 32d and a second eccentric portion 32e are formed at an intermediate position of the sub shaft 32b. The first piston 11A is formed in the first eccentric portion 32d, and the second piston 11B is formed in the second eccentric portion 32e. Each is fitted.

  The evaporator lower flow path 4 e between the evaporator 27 and the compressor 21 passes through the sealed container 30 and is connected to the fixed scroll of the compressor 21. The refrigerant is directly sucked into the compressor 21 through the evaporator lower flow path 4e. As described above, the refrigerant compressed by the compressor 21 is once discharged into the internal space 31 of the sealed container 30 and guided to the radiator 22 through the pipe 41. That is, the compression / expansion unit 3 belongs to a high-pressure shell type compressor in which the internal space 31 of the sealed container 30 is filled with the compressed refrigerant. The refrigerant is separated from the oil while the internal space 31 stays.

  The intermediate pressure channel 4c and the evaporator upper channel 4d pass through the sealed container 30 and are connected to the upper bearing 19B of the expander 26. The refrigerant is directly sucked into the expander 26 through the intermediate pressure channel 4c and is directly discharged from the expander 26 through the evaporator upper channel 4d.

  The downstream end of the second bypass path 6 branched from the evaporator upper flow path 4 d is disposed between the oil level of the oil reservoir 34 and the lower end of the motor 33.

  A pipe 70 constituting an upstream portion of the injection path 7 branched from the intermediate pressure flow path 4 c passes through the sealed container 30 and is connected to the lower bearing 19 </ b> A of the expander 26. The first closing member 16 is provided with an injection port 74, and the downstream portion of the injection path 7 is provided so as to communicate the injection port 74 and the pipe 70 with the lower bearing 19 </ b> A and the first closing member 16. A flow path 72 is used.

3) Configuration of Expander Next, the internal structure of the expander 26 will be described in detail with reference to FIGS. 3 (a) and 3 (b).

  The first piston 11A is eccentrically rotated along the inner peripheral surface of the first cylinder 12A, and the second piston 11B is eccentrically rotated along the inner peripheral surface of the second cylinder 12B. The first cylinder 12A and the second cylinder 12B are arranged such that their inner peripheral surfaces are concentric with each other. The diameter of the inner peripheral surface of the second cylinder 12B is set larger than the diameter of the inner peripheral surface of the first cylinder 12A. Therefore, the volume V2 of the working chamber 13B formed between the inner peripheral surface of the second cylinder 12B and the second piston 11B is formed between the inner peripheral surface of the first cylinder 12A and the first piston 11A. It is larger than the volume V1 of the working chamber 13A. However, the volume V2 of the working chamber 13B is made larger than the volume V1 of the working chamber 13A by making the thickness of the second cylinder 12B and the second piston 11B thicker than the thickness of the first cylinder 12A and the first piston 11A. May be.

  The working chamber 13A in the first cylinder 12A is partitioned into a suction side 131 and a discharge side 132 by the first vane 11A. The first vane 11A is inserted in a vane groove formed in the first cylinder 12A so as to reciprocate. A spring 15 for urging the first vane 14A toward the first piston 11A is disposed in the vane groove. Similarly, the working chamber 13B in the second cylinder 12B is partitioned into a suction side 133 and a discharge side 134 by the second vane 11B. The 2nd vane 11B is inserted in the vane groove formed in the 2nd cylinder 12B so that reciprocation is possible. A spring 15 that biases the second vane 14B toward the second piston 11B is disposed in the vane groove. As described above, in this embodiment, the piston and the vane are brought into contact with each other by the force of the spring, but the joint type is used so that the vane and the piston are not separated, or the piston and the vane (blade) are integrated. It is also possible to adopt a swing type rotary type expander.

  The first vane 14A and the second vane 14B are arranged at positions that overlap in the vertical direction, in other words, at the same angular position with respect to the axis of the sub shaft 32b. The two eccentric portions 32d and 32e of the auxiliary shaft 32b are eccentric in the same direction with respect to the axis of the auxiliary shaft 32b. Therefore, the timing at which the first vane 14A is most retracted radially outward (so-called top dead center) coincides with the timing at which the second vane 14B is most retracted radially outward. Note that these timings may be different from each other.

  A lower bearing 19A and an upper bearing 19B arranged so as to sandwich the first cylinder 12A, the intermediate plate 17, and the second cylinder 12B hold the auxiliary shaft 32b rotatably. The first closing member 16 is disposed on the upper side of the lower bearing 19A and closes the working chamber 13A in the first cylinder 12A from below. The intermediate plate 17 closes the working chamber 13A in the first cylinder 12A from above and closes the working chamber 13B in the second cylinder 12B from below. The second closing member 18 is disposed below the upper bearing 19B and closes the working chamber 13B in the second cylinder 12B from above.

  The intermediate plate 17 is formed with a communication passage 17a that connects the discharge side 132 of the working chamber 13A in the first cylinder 12A and the suction side 133 of the working chamber 13B in the second cylinder 12B. The discharge side 132 of the working chamber 13A, the communication path 17a, and the suction side 133 of the working chamber 13B constitute an expansion chamber in which the refrigerant is expanded inside by a volume change. The communication passage 17a is opened and closed by the pistons 11A and 11B.

  In the present embodiment, the communication path 17 a is an oblique hole whose center line is inclined at a certain angle with respect to the thickness direction of the intermediate plate 17. However, the position of the first vane 14A and the position of the second vane 14B do not overlap in the vertical direction, and these two vanes 14A and 14B are arranged at a predetermined angular interval with respect to the axis of the sub shaft 32b. In this case, the communication path 17a can be formed so as to penetrate the intermediate plate 17 with the shortest distance.

  The upper bearing 19B, the second closing member 18, the second cylinder 12B, the intermediate plate 17, the first cylinder 12A, and the first closing member 16 are formed with a suction passage 26a communicating with the intermediate pressure passage 4c (see FIG. 2). The first closing member 16 is formed with a suction port 26A through which the refrigerant from the intermediate pressure flow path 4c flows into the suction side 131 of the working chamber 13A in the first cylinder 12A via the suction path 26a.

  The upper bearing 19B is formed with a discharge passage 26b communicating with the evaporator upper passage 4d (see FIG. 2). The second closing member 18 is formed with a discharge port 26B through which refrigerant flows out from the discharge side 134 of the working chamber 13B in the second cylinder 12B to the evaporator upper flow path 4d via the discharge path 26b. Further, the discharge port 26B is provided with a discharge valve 26c that functions as a check valve that allows only a flow from the discharge port 26B toward the evaporator upper flow path 4d by elastic deformation.

  As described above, the lower bearing 19A is formed with the flow path 72 communicating with the pipe 70, and the first closing member 16 is connected to the discharge side 132 (expansion) of the working chamber 13A in the first cylinder 12A from the flow path 72. An injection port 74 for allowing the refrigerant to flow into the chamber) is formed. That is, the pipe 70 and the flow path 72 constitute the injection path 7 that guides the refrigerant guided to the suction port 26A to the injection port 74. The injection port 74 is disposed almost directly opposite the opening on the first cylinder 12A side of the communication passage 17a formed in the intermediate plate 17, and the opening is opened and closed at substantially the same timing as the opening and closing of the first piston 11A. The In addition, the flow path 72 is provided with an injection valve 73 that functions as a check valve that allows only a flow from the pipe 70 toward the injection port 74 by elastic deformation.

  Note that the injection port 74 does not necessarily have to flow the refrigerant into the discharge side 132 of the working chamber 13A in the first cylinder 12A, and may be open to the expansion chamber. For example, the injection port 74 may be formed in the second closing member 18 so that the refrigerant flows into the suction side 133 of the working chamber 13B in the second cylinder 12B.

4) Operation of the expander Next, the volume change of the working chamber accompanying the operation of the expander 26 will be described. FIG. 4 shows the change in volume of the working chamber with respect to the rotation angle of the sub shaft 32b with the top dead center position being 0 °. Hereinafter, the suction side 131 of the working chamber 13A in the first cylinder 12A is referred to as a first suction side working chamber 131, and the discharge side 132 is referred to as a first discharge side working chamber 132. Similarly, the suction side 133 of the working chamber 13B in the second cylinder 12B is referred to as a second suction side working chamber 133, and the discharge side 134 is referred to as a second discharge side working chamber 134.

  When the expander 26 operates, the sub shaft 32b rotates counterclockwise in FIGS. 3 (a) and 3 (b). As a result, the first piston 11A and the second piston 11B rotate counterclockwise. In the state where the rotation angle is 0 °, the suction port 26A is closed by the first piston 11A, and the suction port 26A is gradually opened by the movement of the first piston 11A between about 1 to 20 °, and the suction path 26a. Communicates with the first suction-side working chamber 131. The volume of the first suction side working chamber 131 increases until the rotation angle reaches 360 ° and finally becomes the volume V1 of the working chamber 13A, but the suction port 26A is about 340 to 359 °, and the suction port 26A is in the first piston 11A. The suction passage 26a and the first suction side working chamber 131 are divided by being gradually closed. In a state where the rotation angle is 360 °, the suction port 26A, the first cylinder side opening of the communication passage 17a, and the injection port 74 are closed by the first piston 11A, and the working chamber 13A does not communicate with other spaces. When the rotation angle exceeds 360 °, the first suction side working chamber 131 moves to the first discharge side working chamber 132.

  Between the rotation angles 361 to 380 °, the first cylinder side opening of the communication path 17a is gradually opened by the movement of the first piston 11A, and the first discharge side working chamber 132 and the communication path 17a communicate with each other. The second cylinder 11 opening of the communication passage 17a is gradually opened by the movement of the second piston 11B almost simultaneously, and the second suction side working chamber 133 is also connected to the communication passage 17a to form an expansion chamber. Further, the injection port 74 is gradually opened at almost the same timing by the movement of the first piston 11A, the expansion chamber and the injection path 7 communicate with each other, and the refrigerant can flow into the expansion chamber through the flow rate adjustment valve 71. It becomes. As the rotation angle increases from 360 °, the ratio of the second suction side working chamber 133 occupying the expansion chamber increases, so the volume of the expansion chamber increases until the rotation angle reaches 720 °, and finally the working chamber 13B. Volume V2. Between the rotation angles of 700 to 719 °, the second cylinder side opening of the communication passage 17a is gradually closed by the movement of the second piston 11B, and the communication passage 17a and the second suction side working chamber 133 are separated. After the rotation angle of 720 °, the second suction side working chamber 133 moves to the second discharge side working chamber 134.

  At the rotation angles 721 to 1080 °, the volume of the second discharge side working chamber 134 becomes small and finally becomes zero. Since the discharge port 175a is gradually opened by the movement of the second piston 11B during the rotation angle of 700 to 740 °, the refrigerant in the second discharge side working chamber 134 can pass through the discharge valve 26c and flow out to the discharge passage 26b. It becomes.

  Next, a change in the suction volume of the expander 26 due to the refrigerant flowing into the expansion chamber from the injection port 74 will be described. When the flow rate adjustment valve 71 is closed, the refrigerant is not sucked from the injection port 74, so that the refrigerant is sucked only into the first suction side working chamber 131, and the suction volume of the expander 26 is the same as that of the working chamber 13A. The volume is V1. However, by opening the flow rate adjustment valve 71, the refrigerant can be sucked from the injection port 74, and the suction volume of the expander 26 is expanded up to the volume V2 of the working chamber 13B. A specific explanation will be added. When the refrigerant sucked into the first suction side working chamber 131 is expanded in volume in the expansion chamber, the pressure of the refrigerant decreases (expands). When the pressure in the first discharge side working chamber 132 is lower than the pressure in the flow path 72, the injection valve 73 is opened and the refrigerant flows in. If the flow rate adjustment valve 71 is fully open, the pressure of the refrigerant flowing into the flow path 72 becomes almost the same pressure as the refrigerant flowing into the continuous suction path 26a via the pipe 70 and the intermediate pressure flow path 4c. Immediately after the expansion starts, the injection valve 73 is opened, and the refrigerant is sucked in until the volume of the expansion chamber reaches the volume V2 of the working chamber 13B. When the opening of the flow rate adjusting valve 71 is adjusted to change the pressure in the flow path 72, the timing at which the injection valve 73 opens and the density of the refrigerant to be sucked change to change the suction volume of the expander 26 The same flow rate control effect can be obtained. Thus, by changing the opening degree of the flow rate adjustment valve 71 from the closed state to the fully open state, the flow rate control range of the expander 26 is equivalent to the volume V2 of the working chamber 13B from the suction volume corresponding to the volume V1 of the working chamber 13A. Changes to the inhalation volume.

5) Overall operation Next, the operation of the circulating hot water supply system will be described.

  First, the hot water heater 9 will be described. When the hot water heater 9 starts operation, the circulation pump 95 is operated, and the high-temperature water stored in the upper part of the hot water tank 91 is sent to the heater 96. In the heater 96, the high temperature water dissipates heat and becomes medium temperature water. Part or all of the intermediate temperature water flows into the intermediate temperature water heat exchanger 25 depending on the opening degree of the intermediate temperature water flow rate adjustment valve 99 and the bypass flow rate adjustment valve 98. In the intermediate temperature water heat exchanger 25, the intermediate temperature water is cooled by the refrigerant flowing from the gas-liquid separator 24 to the expander 26, and becomes low temperature water. The low-temperature water flows into the lower part of the hot water tank 91 and is temporarily stored and then supplied to the radiator 22 by the boiling pump 93. The low temperature water is heated by the radiator 22 to become high temperature water, and is stored again in the upper part of the hot water tank 91.

  In the hot water tank 91, the upper high temperature water and the lower low temperature water are stored in the same space, and temperature stratification is formed. The hot water tank 91 may be provided with a flow suppressing member for keeping the temperature stratification. In addition to the hot water outlet and the low temperature water outlet, the hot water flows out from the middle part of the temperature stratification and mixes with the hot water or low temperature water to produce water at the temperature required by the user. It may be.

  In the present embodiment, carbon dioxide is used as the refrigerant of the refrigeration cycle apparatus 1A, and the temperature of the high-temperature water can be 65 ° C. to 90 ° C. due to its properties. Therefore, although the medium temperature water is 40 ° C. to 65 ° C. and the low temperature water is 20 ° C. to 40 ° C., the temperature of the water can change depending on the refrigerant charged in the refrigeration cycle apparatus 1A.

  The medium-temperature water gives heat to the refrigerant flowing into the expander 26 in the medium-temperature water heat exchanger 25 and becomes low-temperature water. Depending on the operation state, the temperature of the refrigerant in the medium-temperature water heat exchanger 25 is higher than the temperature of the medium-temperature water. It can be expensive. In that case, the intermediate warm water flow rate adjustment valve 99 is closed and the bypass flow rate adjustment valve 98 is opened to allow the intermediate temperature water to flow into the intermediate warm water bypass passage 97, thereby preventing the temperature of the refrigerant flowing into the expander 26 from being lowered.

  Next, the operation of the refrigeration cycle apparatus 1A will be described. The refrigeration cycle apparatus 1 </ b> A operates while switching between the power recovery operation and the heating capacity enhancement operation according to the condition of the outside air temperature measured by the outside air temperature sensor 81. In the present embodiment, the power recovery operation is an operation in a state where the on-off valve 42 provided in the evaporator upper flow path 4d is opened, and the heating capacity enhancement operation is an operation in a state where the on-off valve 42 is closed. . Hereinafter, each operation will be described with reference to FIGS. 1 and 2 together.

(A) Power recovery operation FIG. 5 is a Mollier diagram showing the cycle state of the power recovery operation. Points A to G indicate the state of the refrigerant at the positions A to G shown in FIG. 1.

  When the compressor 21 is driven by the motor 33, the refrigerant (point A) is sucked into the compressor 21 through the evaporator lower flow path 4e and compressed (point B). The compressed refrigerant is guided to the radiator 22 through the internal space 31 and the pipe 41 of the sealed container 30. The radiator 22 cools the compressed refrigerant (point C). The cooled refrigerant is sucked into the expander 26 via the pre-expansion valve 23 (point D), the gas-liquid separator 24 (point E), and the intermediate temperature water heat exchanger 25 (point F). The expander 26 expands the refrigerant (point G) and collects power from the refrigerant. The expanded refrigerant passes through the discharge valve 26 c, the discharge path 26 b, and the on-off valve 42 and is guided to the evaporator 27. In the evaporator 27, the refrigerant absorbs heat from the outside and evaporates. The evaporated refrigerant is sucked into the compressor 21 again.

  In the expander 26, since the compression shaft 32a and the sub shaft 32b are connected, the flow rate cannot be adjusted by changing the rotation speed with respect to the compressor 21. In other words, the density ratio of the high-pressure side refrigerant and the low-pressure side refrigerant in the refrigeration cycle apparatus 1A cannot be adjusted. Therefore, in the refrigeration cycle apparatus 1A, the density ratio of the refrigerant is adjusted by manipulating the opening degrees of the pre-expansion valve 23, the flow rate adjusting valve 71, and the bypass expansion valve 51.

  When changing the density ratio of the high-pressure side pressure and the low-pressure side pressure of the refrigeration cycle apparatus 1A from small to large, the bypass is started from the state where the pre-expansion valve 23, the flow rate adjustment valve 71 and the bypass expansion valve 51 are all fully opened. The expansion valve 51, the flow rate adjustment valve 71, and the pre-expansion valve 23 are operated in order of decreasing the opening and decreasing the refrigerant flow rate. In the process of decreasing the opening degree of the bypass expansion valve 51, the flow rate of the first bypass passage 5 decreases, and the maximum flow rate flows through the expander 26. In the process of closing the bypass expansion valve 51 and reducing the opening of the flow rate adjustment valve 71, the suction volume of the expander 26 is reduced from the volume V2 of the working chamber 13B to the volume V1 of the working chamber 13A as described above. When the flow rate adjustment valve 71 is closed, the suction volume of the expander 26 is in a minimum state. In the process of reducing the opening degree of the pre-expansion valve 23, the pressure reduction range of the refrigerant in the pre-expansion valve 23 is increased, so that the density of the refrigerant sucked by the expander 26 is reduced and the refrigerant flow rate is reduced. In this way, the density ratio between the high-pressure side refrigerant and the low-pressure side refrigerant of the refrigeration cycle apparatus 1A is adjusted. In FIG. 5, the bypass expansion valve 51 and the flow rate adjustment valve 71 are fully closed, the pre-expansion valve 23 is fully open, and the intermediate warm water flow rate adjustment valve 99 is fully closed. Note that an opening / closing valve may be provided in the first bypass passage 5 and the opening / closing valve may be opened / closed in accordance with the adjustment of the opening degree of the bypass expansion valve 51.

  When the on-off valve 42 is open, the internal pressure of the sealed container 30 is higher than the pressure in the upstream portion of the second bypass passage 6 communicating with the evaporator 27, and the check valve 61 does not open. Therefore, the refrigerant discharged from the expander 26 does not flow into the sealed container 30.

  On the Mollier diagram of FIG. 5, in the normal refrigeration cycle in which the expander 26 is not mounted, the state of the refrigerant after expansion is the same enthalpy point G ′ as the point C. However, when the energy of the refrigerant is recovered by the expander 26, the enthalpy is reduced during the expansion process, and the state of the refrigerant after expansion becomes the point G. The difference [Delta] H in the enthalpy between the point G and the point G 'is recovered power and transmitted to the compressor 21, and the electric input of the compressor 21 is reduced.

  By the way, when the outside air temperature decreases, the temperature around the evaporator 27 decreases, and the heat absorption amount from the atmosphere decreases. Therefore, the refrigeration cycle apparatus 1A is controlled so as to lower the evaporation temperature by lowering the pressure of the refrigerant in the evaporator 27. Specifically, the opening of the pre-expansion valve 23 is reduced, the amount of decompression of the refrigerant is increased, and the refrigerant pressure after expansion is lowered. A Mollier diagram showing the state of the refrigeration cycle apparatus 1A at this time is shown in FIG. The refrigerant depressurized by the pre-expansion valve 23 is reduced to a pressure indicated by a point D, and is then sucked into the expander 26 and expanded while lowering the enthalpy to the position of the point G. At this time, the recovery power recovered by the expander 26 becomes ΔH ′ which is the enthalpy difference between the points D and G, which is smaller than ΔH in FIG. That is, the effect of the power recovery operation may be reduced at a low outside temperature. In such a case, it is effective to perform the heating capacity operation described below.

(B) Heating capacity enhancement operation FIG. 7 is a Mollier diagram showing the cycle state of the heating capacity enhancement operation. Points A to I indicate the state of the refrigerant at positions A to I shown in FIG.

  When the compressor 21 is driven by the motor 33, the refrigerant (point A) is sucked into the compressor 21 through the evaporator lower flow path 4e and compressed (point B). The compressed refrigerant is guided to the radiator 22 through the internal space 31 and the pipe 41 of the sealed container 30. The radiator 22 cools the compressed refrigerant (point C). The cooled refrigerant is depressurized to an intermediate pressure at which the pre-expansion valve 23 becomes a gas-liquid two-phase state (point D), and then separated into a liquid-phase refrigerant and a gas-phase refrigerant in the gas-liquid separator 24. The gas-phase refrigerant (point E) flows into the intermediate temperature water heat exchanger 25, is heated by exchanging heat with the intermediate temperature water (point F), and is sucked into the expander 26 through the intermediate pressure channel 4c and the pipe 70. The flow rate adjustment valve 71 is fully open, and the expander 26 sucks the refrigerant up to the volume V2 of the working chamber 13B. That is, the refrigerant is not expanded. By the rotation of the sub shaft 32b, the refrigerant passes through the discharge valve 26c and the discharge path 26b from the discharge port 26B and is sent out to the evaporator upper flow path 4d. In the heating capacity enhancing operation, the on-off valve 42 is closed, and the internal space of the discharge passage 26b and the upstream portion of the on-off valve 42 in the evaporator upper flow path 4d (hereinafter referred to as “pressure boosting passage”) It is in a state separated from the interior space. Therefore, the internal space of the pressure increasing path is a space that is closed by the on-off valve 42, the check valve 61, and the discharge valve 26c and is continuous with the upstream portion of the second bypass path 6, and the refrigerant is discharged from the expander 26. Every time the density and pressure of the refrigerant rises. That is, the expander 26 functions as a compressor that boosts the refrigerant. When the internal pressure of the pressure increasing path becomes higher than the internal pressure of the sealed container 30 (point G), the check valve 61 opens, and the refrigerant is discharged into the internal space 31 of the sealed container 30 through the downstream portion of the second bypass path 6. The The refrigerant discharged into the internal space 31 merges with the refrigerant discharged from the compressor 21 and is guided to the radiator 22 through the pipe 41. On the other hand, the liquid phase refrigerant (point H) separated in the gas-liquid separator 24 is decompressed by the bypass expansion valve 51 (point I) and then flows into the evaporator 27. In the evaporator 27, the refrigerant absorbs heat from the outside and evaporates. The evaporated refrigerant is sucked into the compressor 21 again.

  In FIG. 7, the vapor phase refrigerant (point E) separated by the gas-liquid separator 24 has a superheat degree close to zero. When heated by the intermediate temperature water heat exchanger 25, the superheat of the gas-phase refrigerant increases (point F). Therefore, when sucked into the expander 26, the refrigerant is in a gas state having a sufficiently superheated degree, and the refrigerant sucked into the expander 26 is prevented from becoming a liquid. The refrigerant sucked into the expander 26 is compressed as described above (point G), and merges with the refrigerant discharged from the compressor 21 and flows into the radiator 22. The refrigerant sucked into the expander 26 has an intermediate pressure, and the required compression power is smaller than when compressing a low-pressure refrigerant. Further, since the pressure is intermediate, the density is higher than that of the low-pressure refrigerant, and the flow rate of the compressed refrigerant is also increased. Therefore, since the refrigerant | coolant flow rate of the heat radiator 22 increases, the heating capability of the heat radiator 22 increases and COP of 1 A of refrigerating-cycle apparatuses improves.

  Switching between the power recovery operation and the heating capacity enhancement operation is performed by an instruction signal from the controller 8. The controller 8 measures the outside air temperature with the outside air temperature sensor 81, determines whether it is a power recovery operation or a heating capacity operation from a pre-stored table according to a combination with a required hot water temperature value, and transmits an instruction signal. To do.

  In the present embodiment, a check valve 61 that allows only the flow from the second bypass path 6 and the evaporator upper flow path 4d toward the radiator upper flow path 4a is provided. The check valve 61 is a differential pressure type, and operates only when the pressure on the upstream side of the second bypass passage 6 is lower than the pressure on the downstream side. Therefore, during the power recovery operation, the check valve 61 is automatically closed and high pressure flows in by simply opening the on-off valve 42 and setting the upstream side of the second bypass 6 to the same low-pressure refrigerant state as the evaporator 27. There is no danger. When the heating capacity enhancing operation is performed, the on-off valve 42 is closed to close the pressure increasing path, the pressure is increased by the pressure of the refrigerant sent out, the check valve 61 is automatically opened, and the high-pressure refrigerant flows into the sealed container 30. Flows into. Thus, the operation can be switched only by opening and closing the on-off valve 42, and the configuration and control can be simplified.

  However, the switching means of the present invention does not need to be composed of the check valve 61 and the on-off valve 42 as in the present embodiment. For example, a simple on-off valve may be used instead of the check valve 61, or a three-way valve provided at a position where the second bypass path 6 branches in the evaporator upper flow path 4d may be employed as the switching means. . In these cases, when the refrigerant discharged from the expander 26 is guided to the radiator upper flow path 4a through the second bypass passage 6, the upstream side of the on-off valve 42 or the three-way valve at the moment of such switching. Since the pressure in the pressure increasing path is the same as the pressure in the sealed container 30, the refrigerant can be boosted to the pressure in the sealed container 30 by forcibly sending the refrigerant by the expander 26.

  In the present embodiment, a gas-liquid separator 24 is provided, and the refrigerant after being expanded by the pre-expansion valve 23 is separated into a gas-phase refrigerant and a liquid-phase refrigerant. By doing so, the refrigerant sucked into the expander 26 becomes gas and can be compressed from a state where the enthalpy of the refrigerant is high, so that the enthalpy of the discharged refrigerant is also increased and the heating capacity is improved. Further, since the liquid-phase refrigerant is reduced in pressure by the bypass expansion valve 51 via the first bypass passage 5 and then flows into the evaporator 27, the ratio of the refrigerant liquid flowing into the evaporator 27 increases, thereby evaporating. The heat exchange efficiency in the cooler is improved, the pressure loss is also reduced, and the COP of the refrigeration cycle apparatus 1A is improved.

  In order to ensure the reliability of the expander 26, it is desirable that the refrigerant to be sucked is in a gas phase. This is because when the liquid phase refrigerant is sucked and compressed, the incompressible fluid is compressed, and a large stress acts on the inside of the expander 26, and the member may be damaged. In order not to suck the liquid refrigerant, it is necessary not to make the suction volume of the expander 26 too large, and to make the amount of the vapor refrigerant separated and remaining in the gas-liquid separator 24 not zero. Specifically, the suction volume of the expander 26 may be set to a size of about 1/20 to 1/2 of the suction volume of the compressor 21. Further, in order to make the refrigerant sucked by the expander 26 into the gas phase, the opening of the pre-expansion valve 23 and the bypass expansion valve 51 is adjusted to control the pressure of the refrigerant after depressurization at the pre-expansion valve 23. Is also effective. Specifically, it is desirable to adjust the refrigerant pressure after depressurization at the pre-expansion valve 23 to be about 4 to 6 MPa.

  In the present embodiment, the enthalpy is further increased by heating the gas-phase refrigerant flowing into the expander 26 with the return water of the hot water heating device 9 in the intermediate hot water heat exchanger 25. As a result, the discharge temperature of the expander 26 is improved, the heating capacity is improved, and the degree of superheat of the refrigerant flowing into the expander 26 can be increased, so that the expander 26 is reliably prevented from sucking liquid refrigerant. The reliability of the expander 26 can be improved. Further, unnecessary heat of the return water can be effectively utilized, and the temperature of the water flowing into the radiator 22 is lowered by cooling the return water, so that the pressure of the refrigerant flowing through the radiator 22 can be reduced. Therefore, the refrigerant compression power by the compressor 21 can be reduced, and the COP of the refrigeration cycle apparatus 1A is further improved.

  The flow rate of the return water flowing through the intermediate temperature water heat exchanger 25 can be changed by adjusting the opening degree of the bypass flow rate adjustment valve 98 and the intermediate temperature water flow rate adjustment valve 99. As a result, the refrigerant flowing into the expander 26 can be prevented from being overheated and the degree of superheat can be maintained appropriately, so that excessive temperature rise of the refrigerant after compression is prevented, and deterioration of the lubricating oil is prevented. The reliability of the unit 3 can be improved.

  In the present embodiment, the compressor 21 is connected by an expander 26 and a shaft 32 and is driven by a motor 33. By doing so, the power recovered by the expander 26 is directly transmitted to the compressor 21 when the power recovery operation is being executed, and the power of the motor 33 is directly expanded when the heating capacity enhancing operation is being executed. Since it is transmitted to the machine 26, electric control of power running and regeneration is not required when switching between these operations, the control method is simplified, and the cost can be reduced. In addition, power can be transmitted efficiently without energy conversion into electrical energy or the like.

  Furthermore, in the present embodiment, the downstream end of the second bypass path 6 opens into the sealed container 30 that encloses the motor 33. By doing so, the refrigerant compressed by the expander 26 can be discharged into the sealed container 30. The refrigerant sucked into the expander 26 is an intermediate-pressure gas-phase refrigerant and is in a state near the gas-liquid two-phase boundary, so that the discharge refrigerant temperature after compression is lower than the discharge refrigerant temperature of the compressor 21. Therefore, the temperature of the discharged refrigerant once retained in the sealed container 30 can be lowered and the motor 33 can be cooled. As a result, the reliability of the motor 33 is improved, and the compressor 21 can be operated up to a high-speed rotation range that could not be operated due to the temperature rise of the motor 33 until now. Can be further improved.

  Further, the expander 26 of the present embodiment includes a discharge valve 26c between the discharge port 26B and the discharge path 26b. When the refrigeration cycle apparatus 1A performs the heating capacity enhancing operation, the expander 26 compresses the refrigerant, so that the discharge destination refrigerant has a high pressure. Since the discharge valve 26c is provided, the high-pressure refrigerant does not flow back to the second discharge-side working chamber 134, so the expander 26 can efficiently compress the refrigerant. Even when the discharge valve 26 c is not provided, the refrigerant is compressed by forced delivery by the expander 26.

  The expander 26 of this embodiment is added with an injection mechanism including an injection path 7 (a pipe 70, a flow rate adjustment valve 71, a flow path 72, an injection valve 73) and an injection port 74. Since the refrigerant flow rate of the expander 26 can be changed by this injection mechanism, the refrigerant flow rate can be adjusted according to the required heating capacity even when the heating capacity enhancement operation is performed, and the refrigeration cycle apparatus 1A can be efficiently used. Can drive well.

  Further, the injection mechanism of the present embodiment is configured such that the expander 26 can suck the refrigerant until the expansion chamber has a maximum volume (volume V2 of the working chamber 13B). Therefore, since the refrigerant flow rate can be changed widely by utilizing the volume change from the working chamber 13A to the working chamber 13B in the expansion chamber of the expander 26, the heating capacity can be improved corresponding to various operating conditions. The COP of the refrigeration cycle apparatus 1A can be improved.

  Further, in the present embodiment, when performing the heating capacity enhancing operation, the flow rate adjustment valve 71 is fully opened and the refrigerant having substantially the same pressure as the refrigerant flowing in from the suction port 26A is controlled from the injection port 74 to the expansion chamber. . As a result, the pressure in the first suction side working chamber 131 of the expander 26 and the pressure in the expansion chamber become substantially equal, so that the force due to the pressure difference of the working chamber does not act on the first piston 11A and the first eccentric portion 32d. The power of the motor 33 can be used only in the compression process in the second discharge side working chamber 134. Therefore, the refrigerant can be efficiently compressed in the expander 26, and the COP of the refrigeration cycle apparatus 1A is improved.

  In the present embodiment, a two-stage rotary type is adopted as the type of the expander 26. In this way, the expander 26 can be configured without providing a complicated suction mechanism. Also, it is easy to provide an injection mechanism as compared with other types of scroll type fluid machines and the like, and a highly efficient refrigeration cycle apparatus 1A can be provided at a low manufacturing cost.

  Carbon dioxide is enclosed as a refrigerant in the refrigeration cycle apparatus 1A of the present embodiment. Since carbon dioxide has a large pressure difference between the high-pressure side refrigerant and the low-pressure side refrigerant and the pressure energy of the refrigerant is large, the amount of power recovered from the expanding refrigerant increases, and the COP of the refrigeration cycle apparatus 1A can be improved. .

(Modification 1)
FIG. 8 shows a case where the second bypass path 6 is disposed in the sealed container 30 and the pressure increasing valve 62 functioning as a check valve is used by elastically deforming instead of the check valve 61 of the first embodiment. 3 is an enlarged view of the expander 26. FIG. Hereinafter, parts that are not changed compared to the first embodiment are denoted by the same reference numerals as in the first embodiment.

  The second bypass path 6 is provided in the upper bearing 19 </ b> B so as to communicate the discharge path 26 b and the internal space 31 of the sealed container 30. The pressure increasing valve 62 is attached in such a direction as to open only when the pressure in the discharge passage 26 b becomes higher than the pressure in the sealed container 30. Therefore, when the on-off valve 42 is closed and operated in the same manner as in the first embodiment, the pressure in the pressure increasing path (the upstream side of the opening / closing valve 42 in the discharge path 26b and the evaporator upper flow path 4d) increases, and the pressure is increased. The valve 62 is opened, and the refrigerant is discharged into the internal space 31 via the second bypass 6. That is, the heating capacity enhancing operation can be performed as in the first embodiment. Needless to say, if the on-off valve 42 is opened for operation, the power recovery operation can be performed. That is, the on-off valve 42 and the booster valve 62 switch whether the refrigerant discharged from the expander 26 is guided to the evaporator 27 through the evaporator upper flow path 4d or to the radiator upper flow path 4a through the second bypass path 6. The switching means is configured.

  In this case, there is no need to provide the check valve 61 outside the sealed container 30 provided in the first embodiment, the piping for configuring the second bypass 6, etc., so material costs, processing costs, etc. Lead to cost reduction. In addition, since the refrigerant discharged during the heating capacity enhancement operation is discharged inside without exiting from the hermetic container 30, heat loss and pressure loss due to piping can be prevented.

(Modification 2)
FIG. 9 shows a cross-sectional view when the expander 26 of the compression / expansion unit 3 in the first embodiment is a single-stage rotary expander.

  The expander 26 includes a lower bearing 19A, a first closing member 16A, a cylinder 12, a second closing member 16B, and an upper bearing 19B stacked in order from the bottom. The sub shaft 32b penetrates through the center. A piston 11 is disposed in a space surrounded by the first closing member 16A, the cylinder 12, and the second closing member 16B, and the piston 11 is fitted with an eccentric portion 31f formed on the sub shaft 32b. As shown in FIG. 10, a working chamber 13 is formed between the inner peripheral surface of the cylinder 21 and the piston 11. A vane 14 that divides the working chamber 13 into a suction side 13a and a discharge side 13b is inserted into a vane groove formed in the cylinder 12 so as to be able to reciprocate. A spring 15 that biases the vane 14 toward the piston 11 is disposed in the vane groove.

  The first closing member 16A and the second closing member 16B close the working chamber 13 from above and below. A suction port 26A is formed in the first closing member 16A so as to open to the suction side 13a of the working chamber 13, and a discharge port 26B is opened to the discharge side 13b of the working chamber 13 in the second closing member 18. Is formed. Both the suction port 26A and the discharge port 26B are arranged on both sides of the vane 11 when viewed from the axial direction of the sub shaft 32b. The suction port 26A communicates with the intermediate pressure flow path 4c via the suction path 26a, and the discharge port 26B communicates with the evaporator upper flow path 4d via the discharge path 26b. Further, the discharge port 26B is provided with a discharge valve 26c as in the first embodiment.

  Next, the behavior of the refrigerant when the single-stage rotary expander 26 is used will be described.

  In the power recovery operation, the on-off valve 42 is opened as in the first embodiment. The refrigerant flowing out from the radiator 22 flows into the suction side working chamber 13a from the suction port 26A via the pre-expansion valve 23 and the gas-liquid separator 24. When the rotation angle of the sub shaft 32b reaches about 340 to 359 °, the suction port 26A is gradually closed by the movement of the piston 11, and the suction of the refrigerant is completed. When the rotation angle reaches about 361 to 380 °, the discharge port 26B that has been closed by the piston 11 is gradually opened. At this time, since the pressure in the discharge passage 26b is substantially the same as the pressure in the evaporator 27, the discharge valve 26c is opened simultaneously with the opening of the discharge port 26B. As a result, the refrigerant starts to flow out from the discharge side working chamber 13b, and the pressure in the discharge side working chamber 13b rapidly decreases to about the pressure in the evaporator 27. And a refrigerant | coolant expands instantaneously with a pressure fall. That is, the single-stage rotary expander 26 is a fluid pressure motor type power recovery mechanism that rotates the piston 11, the eccentric portion 32f, and the sub shaft 32b by the pressure difference between the suction side working chamber 13a and the discharge side working chamber 13b. To recover power. As described above, in the single-stage rotary expander 26, there is no refrigerant expansion process in the expansion chamber, which is present in the case of the two-stage rotary expander. Note that the opening / closing timings of the suction port 26A and the discharge port 26B do not have to be as described above, as long as the pressure difference is generated between the suction side working chamber 13a and the discharge side working chamber 13b.

  During the heating capacity enhancing operation, the on-off valve 42 is closed. For this reason, the pressure in the pressure rising path gradually increases and eventually becomes higher than the pressure in the discharge side working chamber 13b. When this happens, the refrigerant no longer expands due to the pressure difference, and the refrigerant is compressed in the space closed by the discharge valve 26c in the discharge side working chamber 13b. And when the pressure of the discharge side working chamber 13b becomes larger than the pressure of the discharge path 26b, the discharge valve 26c opens and the compressed refrigerant flows out. In this way, when the pressure in the pressure increasing path rises higher than the pressure in the sealed container 30, the check valve 61 is now opened, and the refrigerant compressed to that pressure is guided to the radiator upper flow path 4a. Thereby, the heating capability of refrigeration cycle apparatus 1A increases like 1st Embodiment.

  In the present embodiment, the two-stage rotary expander is not provided with an injection mechanism for sucking the refrigerant without expanding it. However, the refrigerant does not expand and cause a loss. Because the expander 26 is a single-stage rotary type and does not have a suction timing control mechanism, there is no process of expanding the volume while confining the refrigerant, and there is no expansion of the refrigerant accompanying such a volume change. is there. Therefore, when the single-stage rotary expander 26 is used, the COP of the refrigeration cycle apparatus 1A can be improved while suppressing the cost.

  If the single-stage rotary expander 26 is provided with a mechanism for limiting the refrigerant suction timing and includes a process of recovering power while expanding the refrigerant, the two-stage rotary type described in the first embodiment is used. The refrigerant behavior similar to that of the expander 26 is shown.

Second Embodiment
FIG. 11 is a configuration diagram of a circulating hot water supply system using the refrigeration cycle apparatus 1B according to the second embodiment of the present invention. Hereinafter, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The heating path 94 of the hot water heater 7 is configured to directly return the water radiated by the heater 96 to the hot water tank 91. Moreover, the refrigeration cycle apparatus 1B includes an internal heat exchanger 28 instead of the intermediate temperature water heat exchanger 25 (see FIG. 1). Furthermore, in this embodiment, the compressor 21 and the expander 26 are accommodated in separate sealed containers.

  Specifically, the compressor 21 is disposed in the first sealed container 35 together with the motor 33 connected by the compression shaft 32 b, and the expander 26 is disposed in the second sealed container 36. Also in this embodiment, the compressor 21 discharges the compressed refrigerant into the internal space 36 of the first sealed container 35.

  Further, in the second sealed container 36, power generation that can give rotational power to the sub-shaft 32 b connected to the expander 26, or convert the rotational power transmitted from the sub-shaft 32 b into electric energy. A machine 38 is arranged.

  In the present embodiment, the first bypass path 5 branches from the radiator lower flow path 4b between the radiator 22 and the pre-expansion valve 23 and is connected to the evaporator upper flow path 4d. The internal heat exchanger 28 heats the refrigerant flowing through the intermediate pressure flow path 4 c by heat exchange with the refrigerant flowing through the upstream portion of the first bypass path 5 relative to the bypass expansion valve 51.

  Further, in the present embodiment, the downstream end of the second bypass path 6 is connected to a pipe 41 having one end opened to the internal space 36 of the first sealed container 35 and the other end connected to the radiator 22.

  Next, an operation method of the refrigeration cycle apparatus 1B of the second embodiment will be described. FIG. 12 is a Mollier diagram showing the cycle state of the heating capacity enhancement operation. Points A to H indicate the state of the refrigerant at the positions A to H shown in FIG. 11. The cycle state of the power recovery operation is the same as that in FIG. 5 except that the gas-liquid separator is not provided (that is, there is no point E).

(A) Power recovery operation This will be described with reference to FIGS. 11 and 5. When the compressor 21 is driven by the motor 33, the refrigerant (point A) is sucked into the compressor 21 through the evaporator upper flow path 4e and compressed (point B). The compressed refrigerant is guided to the radiator 22 through the internal space 36 and the pipe 41 of the first sealed container 35. The radiator 22 cools the compressed refrigerant (point C). The cooled refrigerant is sucked into the expander 26 via the pre-expansion valve 23 (point D) and the internal heat exchanger 28 (point F). The expander 26 expands the refrigerant (point G) and collects power from the refrigerant. The expanded refrigerant passes through the discharge path 26b (see FIG. 2) and the on-off valve 42 and is guided to the evaporator 27. In the evaporator 27, the refrigerant absorbs heat from the outside and evaporates. The evaporated refrigerant is sucked into the compressor 21 again.

  The expander 26 transmits the recovered power to the sub shaft 32b and drives the generator 38. The generator 38 converts motive power into electrical energy and uses it as part of the input power of the motor 33 that drives the compressor 21.

  In addition to converting power into electrical energy, the generator 38 also controls the rotational speed of the expander 26 and adjusts the flow rate of the refrigerant. When it is desired to increase the pressure difference of the refrigeration cycle apparatus 1B, the rotational speed of the expander 26 can be decreased to decrease the flow rate, and when the pressure difference is decreased, the rotational speed can be increased to increase the flow rate. However, in general, the rotational speed of a rotating machine is limited from the viewpoint of reliability. If the flow rate is still large even when the lower limit of the rotational speed is reached, the flow rate of the refrigerant can be lowered by reducing the opening of the pre-expansion valve 23. If the flow rate is still small even after reaching the upper limit of the rotational speed, the opening degree of the flow rate adjustment valve 71 is increased, and if it is still necessary to increase the flow rate, the opening degree of the bypass expansion valve 51 is increased. And earn a flow rate.

  If the opening degree of the pre-expansion valve 23 is decreased to reduce the flow rate, the pressure of the refrigerant sucked in the expander 26 is reduced, resulting in a state where there is almost no power recovery amount as shown in FIG. End up. In such a case, the expander 26 can be used more effectively by performing the heating capacity enhancing operation described below.

(B) Heating capacity enhancement operation This will be described with reference to FIGS. 11 and 12. When the compressor 21 is driven by the motor 33, the refrigerant (point A) is sucked into the compressor 21 through the evaporator upper flow path 4e and compressed. The compressed refrigerant is guided to the radiator 22 through the internal space 36 and the pipe 41 of the first sealed container 35. The radiator 22 cools the compressed refrigerant (point C). The cooled refrigerant is divided into a part flowing into the first bypass passage 5 and a part toward the pre-expansion valve 23, and the refrigerant that has passed through the pre-expansion valve 23 is decompressed to an intermediate pressure at which a gas-liquid two-phase state is achieved. (Point D) Heat is exchanged with the refrigerant flowing through the first bypass path 5 in the internal heat exchanger 28 (Point F). Thereafter, the air is sucked into the expander 26 through the intermediate pressure flow path 4 c and the pipe 70. The flow rate adjustment valve 71 is fully open, and the expander 26 sucks the refrigerant up to the maximum volume. That is, the refrigerant is not expanded. The refrigerant passes through the discharge valve 26c and the discharge path 26b and is sent out to the evaporator upper flow path 4d by the rotation of the sub shaft 32b driven by the power generator 38 that performs the power running operation. In the heating capacity enhancing operation, the opening / closing valve 42 is closed, and the internal space of the pressure increasing path (the upstream side of the opening / closing valve 42 in the discharge path 26b and the evaporator upper flow path 4d) is separated from the internal space of the evaporator 27. It is in the state. Therefore, the internal space of the pressure increasing path is a space that is closed by the on-off valve 42, the check valve 61, and the discharge valve 26c and is continuous with the upstream portion of the second bypass path 6, and the refrigerant is discharged from the expander 26. Every time the density and pressure of the refrigerant rises. That is, the expander 26 functions as a compressor that boosts the refrigerant. When the internal pressure of the pressure increasing path becomes higher than the internal pressure of the first sealed container 35 (point G), the check valve 61 opens, and the refrigerant is discharged into the pipe 41 through the downstream portion of the second bypass path 6 and compressed. It merges with the refrigerant discharged from the machine 21 and is guided to the radiator 22. On the other hand, the refrigerant that has flowed into the first bypass passage 6 is cooled by exchanging heat with the refrigerant that has passed through the pre-expansion valve 23 in the internal heat exchanger 28 (point H) and reduced in pressure by the bypass expansion valve 51 (point I) flows into the evaporator 27. In the evaporator 27, the refrigerant absorbs heat from the outside and evaporates. The evaporated refrigerant is sucked into the compressor 21 again.

  The refrigerant that has passed through the pre-expansion valve 23 is depressurized and becomes a gas-liquid two-phase intermediate-pressure refrigerant. However, when the liquid-phase refrigerant is sucked into the expander 26 and compressed, it becomes compression of an incompressible fluid, and the expander 26 reliability is impaired. In this embodiment, the internal heat exchanger 28 is configured to superheat the gas-liquid two-phase refrigerant and evaporate the liquid-phase refrigerant. By doing so, the degree of superheat of the refrigerant sucked in the expander 26 can be increased without providing a gas-liquid separator, so that the cost is reduced and the reliability of the expander 26 is improved.

  In the present embodiment, the compressor 21 and the expander 26 are in a so-called separation type in which they are housed in separate sealed containers. Since the rotational speed can be made different between the compressor 21 and the expander 26 in the separated type, the recovered power is extremely reduced by the pre-expansion valve 23 in the power recovery operation. Less than the refrigeration cycle apparatus 1A shown. However, when the operation is performed with a large load near the limit value, the heating capacity enhancement operation is performed to effectively operate the expander 26 and reduce the load of refrigerant compression from the intermediate pressure. Operation in a small state can be performed. Therefore, since the reliability of the expander 26 can be improved, the present invention is effective even in a refrigeration cycle apparatus in a separate type.

  The present invention can be applied not only to a high-pressure shell type refrigeration cycle apparatus in which a compressor discharges a refrigerant into an airtight container, but also to refrigeration cycle apparatuses having other pressure configurations such as an intermediate-pressure shell and a low-pressure shell. In that case, as shown in the second embodiment, the same effect can be obtained by connecting the downstream end of the second bypass 6 to the high-pressure side refrigerant space.

  Also in the second embodiment, similarly to the first embodiment, the downstream end of the second bypass path 6 may be opened in the first sealed container 35.

  The refrigeration cycle apparatus of the present invention can be used for devices such as a hot water heater, a hot water heater, and an air conditioner.

1A, 1B Refrigeration cycle apparatus 21 Compressor 22 Radiator 23 Pre-expansion valve (first decompressor)
24 Gas-liquid separator 25 Medium-temperature water heat exchanger (water-based heat exchanger, heating means)
26 expander 27 evaporator 28 internal heat exchanger (heating means)
30, 35, 37 Sealed container 32a Compression shaft 32b Sub shaft 33 Motor 4 Refrigerant circuit 4a Radiator upper flow path 4b Radiator lower flow path 4c Intermediate pressure flow path 4d Evaporator upper flow path 42 Open / close valve 5 First bypass path 51 Bypass expansion valve ( Second decompressor)
6 Second bypass passage 61 Check valve 7 Injection passage 71 Flow rate adjustment valve (injection valve)

Claims (13)

A compressor that compresses the refrigerant, a radiator that cools the compressed refrigerant, a first decompressor that decompresses the cooled refrigerant, an expander that expands the decompressed refrigerant to recover power, and heats the expanded refrigerant A refrigerant circuit including an evaporator;
Branching from a radiator lower flow path between the radiator and the first pressure reducer in the refrigerant circuit or an intermediate pressure flow path between the first pressure reducer and the expander, the expander in the refrigerant circuit and the A first bypass path provided with a second decompressor for decompressing the refrigerant, connected to the evaporator upper flow path between the evaporators;
A second bypass path branched from the evaporator upper flow path upstream of a position where the first bypass path is connected, and connected to a radiator upper flow path between the compressor and the radiator in the refrigerant circuit;
Switching means for switching whether the refrigerant discharged from the expander is guided to the evaporator through the evaporator upper flow path or to the radiator upper flow path through the second bypass path;
A refrigeration cycle apparatus comprising:   The switching means includes an on-off valve provided on the downstream side of a position where the second bypass path of the evaporator upper flow path branches, and a check valve provided on the second bypass path. The refrigeration cycle apparatus according to 1. The intermediate pressure flow path is provided with a gas-liquid separator that separates the refrigerant decompressed by the first pressure reducer into a gas-phase refrigerant and a liquid-phase refrigerant, and the intermediate pressure flow path is the gas-liquid separator. It is configured to guide the separated gas phase refrigerant to the expander,
The refrigeration cycle apparatus according to claim 1 or 2, wherein the first bypass path is configured to guide the liquid-phase refrigerant separated by the gas-liquid separator to the radiator upper flow path.   The refrigeration cycle apparatus according to claim 1, further comprising a heating unit that heats the refrigerant guided to the expander through the intermediate pressure flow path. The refrigeration cycle apparatus is used in a circulating hot water supply system that circulates water heated by the radiator.
5. The refrigeration cycle apparatus according to claim 4, wherein the heating unit is a water-use heat exchanger that heats the refrigerant using heat of return water after heat radiation. The first bypass path branches off from the radiator lower flow path,
The said heating means is an internal heat exchanger which performs heat exchange between the refrigerant | coolant which flows through the upstream part rather than the said 2nd pressure reduction device in the said 1st bypass channel, and the refrigerant | coolant which flows through the said intermediate pressure flow path. The refrigeration cycle apparatus described in 1. A motor that drives the compressor via a shaft; and a sealed container that houses the compressor and the motor;
The compressor is configured to discharge a compressed refrigerant into the sealed container,
The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein a downstream end of the second bypass path is opened in the sealed container.   The refrigeration cycle apparatus according to claim 7, wherein the expander is coupled to the shaft so that the recovered power can be transmitted to the shaft. The expander has a discharge port for discharging refrigerant,
The refrigeration cycle apparatus according to any one of claims 1 to 8, wherein the discharge port is provided with a discharge valve that prevents back flow of the refrigerant. The expander has a suction port for sucking refrigerant, an expansion chamber that expands the refrigerant inside by a volume change, and an injection port that opens to the expansion chamber,
10. The apparatus according to claim 1, further comprising: an injection path that guides the refrigerant guided to the suction port to the injection port; and an injection valve that prohibits or permits the circulation of the refrigerant through the injection path. Refrigeration cycle equipment.   The injection valve permits the refrigerant to flow through the injection path when the refrigerant discharged from the expander by the switching unit is guided to the radiator upper flow path through the second bypass path. The refrigeration cycle apparatus described in 1.   The refrigeration cycle apparatus according to claim 1, wherein the expander is a two-stage rotary expander.   The refrigeration cycle apparatus according to claim 1, wherein the refrigerant is carbon dioxide.

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