JP2008106668A - Expander, expander-integrated compressor and refrigeration cycle device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover expansion energy of working fluid in a power recovery type refrigeration cycle device. <P>SOLUTION: The expander is provided with a first fluid chamber 33a and a second fluid chamber 33b sucking and expanding working fluid, an auxiliary chamber 81 communicating with the first fluid chamber 33a, and a volume change device 80. The volume change device 80 is provided with a piston dividing the auxiliary chamber 81 into a back pressure chamber 82 in which fluid is filled and a variable volume chamber 83 communicating with the first fluid chamber 33a, and a control device 14 controlling pressure of the fluid filled in the back pressure chamber 82. Pressure of the working fluid in the back pressure chamber 82 is controlled to a pressure lower than a pressure of the working fluid sucked in the first fluid chamber 33a and higher than a pressure of the working fluid discharged from the second fluid chamber 33b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an expander, an expander-integrated compressor, and a refrigeration cycle apparatus using the expander.

  A power recovery type refrigeration cycle apparatus that recovers expansion energy of a working fluid generated in an expander and uses it for compression of the working fluid in a compressor has been proposed. As such a refrigeration cycle apparatus, a refrigeration cycle apparatus using an expander-integrated compressor in which an expander and a compressor are connected by a rotating shaft is known (for example, see Patent Document 1).

  In general, a refrigeration cycle apparatus using an expander-integrated compressor as described above includes a refrigerant circuit that sequentially connects a compressor, a radiator, an expander, and an evaporator. The compressor and the expander are connected by a rotating shaft. In addition, an electric motor that rotationally drives the rotating shaft is provided between the compressor and the expander of the rotating shaft. The working fluid is compressed from a medium temperature and low pressure state to a high temperature and high pressure state in a compressor, and then cooled to a medium temperature and high pressure state in a radiator. And after expanding to a low temperature low pressure state in an expander, it is heated with an evaporator and returns to a medium temperature low pressure state. The expander recovers the expansion energy of the working fluid and converts it into rotational energy that rotates the rotating shaft. This rotational energy is used as part of the work for driving the compressor, and as a result, the power of the electric motor is reduced.

  Here, the volume of the compression chamber immediately after the compression chamber is shut off from the inflow side in the compressor is Vcs, the volume of the expansion chamber immediately after the expansion chamber is shut off from the inflow side in the expander is Ves, When the rotation speed is N, the volume flow rate of the working fluid on the suction side of the compressor is (Vcs × N), and the volume flow rate of the working fluid on the suction side of the expander is (Ves × N). The mass flow rate in the compressor is equal to the mass flow rate in the expander. If this mass flow rate is G, the density of the working fluid on the suction side of the compressor is {G / (Vcs × N)}. The density of the working fluid on the suction side is {G / (Ves × N)}. From these equations, the ratio (density ratio) between the density of the working fluid on the suction side of the compressor and the density of the working fluid on the suction side of the expander is {G / (Vcs × N)} / {G / ( Ves × N)}, that is, (Ves / Vcs), and is restricted to a constant value.

  As in the refrigeration cycle apparatus, when the density ratio of the working fluid on the suction side of the compressor and the suction side of the expander is restricted to a constant value, free control of the refrigeration cycle is hindered. Specifically, in the refrigeration cycle apparatus, at a predetermined heat source temperature, the high pressure side pressure (pressure of the working fluid from the compressor being discharged to the expander) is the optimum pressure (pressure at which the coefficient of performance COP is maximized) ). On the other hand, the high-pressure side pressure and the low-pressure side pressure of the refrigeration cycle (the pressure of the working fluid until it is discharged from the expander and sucked into the compressor) vary depending on operating conditions such as the temperature change of the cooling target and the heat dissipation target. Therefore, the ratio between the density of the working fluid on the suction side of the compressor and the density of the working fluid on the suction side of the expander varies depending on the operating conditions. However, in the above-described refrigeration cycle apparatus, the density ratio is restricted to a constant value (Ves / Vcs), so the temperature and pressure of the working fluid cannot be freely controlled. For this reason, when the operating condition deviates from a predetermined value, the expander is in a so-called overexpansion or underexpansion state, and there is a problem in that the expansion energy of the working fluid cannot be efficiently recovered in the expander.

  Such a problem occurs not only in the expander-integrated compressor, but also in a power recovery type refrigeration cycle apparatus using a separate compressor and expander. When a separation type expander is used, the expansion energy of the working fluid is recovered by a generator connected to the expander. Since the power generation efficiency of the generator decreases as it goes away from the rated speed, it is desirable that the generator be operated near the rated speed. However, in the refrigeration cycle, since the circulation amount and density of the working fluid change according to the operating conditions, it is difficult to keep the generator close to the rated rotational speed. For this reason, even in the separation type expander, there is a problem in that the expansion energy of the working fluid cannot be efficiently recovered in the expander when the operating condition deviates from a predetermined one.

Therefore, an expander has been proposed in which an expansion chamber that communicates with the expansion chamber is provided in the expansion chamber of the expander, and the volume of the expander itself can be changed by changing the volume of the auxiliary chamber according to operating conditions. (For example, refer to Patent Document 2). In the expander, the expansion energy of the working fluid is efficiently recovered in the expander by changing the volume of the expander according to the operating conditions.
JP 2001-116371 A JP 2006-46257 A

  However, in the expander disclosed in Patent Document 2, the auxiliary chamber is always present during one cycle including the suction process, the expansion process, and the discharge process. Thereby, even after the expansion process is completed, the working fluid in the auxiliary chamber remains without being discharged. Therefore, in the subsequent cycles, the auxiliary chamber does not substantially contribute to expanding the volume (suction volume) of the expander and becomes a dead volume. Therefore, the expander has a problem that the expansion energy of the working fluid cannot be recovered efficiently.

  The present invention has been made in view of such points, and an object of the present invention is to efficiently recover expansion energy of a working fluid in a power recovery type refrigeration cycle apparatus.

  An expander according to the present invention is an expander used in a refrigeration cycle apparatus, and includes a fluid chamber for circulating a working fluid, and a volume changing device capable of changing a suction volume of the fluid chamber, and the volume change. The apparatus performs one cycle including a suction process for sucking the working fluid into the fluid chamber, an expansion process for expanding the sucked working fluid, and a discharge process for discharging the expanded working fluid to the outside of the fluid chamber. During this time, the volume of the fluid chamber is increased or decreased.

  Here, the suction volume refers to the volume of the fluid chamber at the end of the suction process.

  The expander includes a volume changing device that changes the suction volume of the fluid chamber. Therefore, according to the expander, the expansion energy of the working fluid can be efficiently recovered by changing the suction volume of the fluid chamber according to the operating conditions. In addition, since the present expander is configured so that the volume of the fluid chamber can be increased or decreased during one cycle, it does not cause a dead volume (or suppresses the dead volume as in a conventional expander). ), The suction volume of the fluid chamber can be increased or decreased.

  The fluid chamber includes a main fluid chamber and a variable volume chamber configured to be able to communicate with the main fluid chamber, and the variable volume chamber increases in volume during the suction process, Preferably, the volume decreases to zero or minimum during the discharge process.

  According to the expander, the suction volume is changed by increasing the volume of the variable volume chamber during the suction process. In addition, dead volume is suppressed by reducing the volume during the expansion process or the discharge process.

  The fluid chamber includes a main fluid chamber and a variable volume chamber configured to be able to communicate with the main fluid chamber, and the variable volume chamber is in communication with the main fluid chamber during the suction process. After the volume is reduced while communicating with the main fluid chamber during the expansion process, the volume becomes zero or minimum before the main fluid chamber is not in communication with the main fluid chamber. It is preferable to maintain a non-communication state with the main fluid chamber.

  According to the expander, the variable volume chamber is generated when the variable volume chamber and the fluid chamber communicate with each other during the suction process, and disappears or disappears before the variable volume chamber and the fluid chamber are disconnected from each other during the expansion process. Minimize. Therefore, it is possible to prevent the working fluid from remaining in the variable volume chamber when the variable volume chamber and the fluid chamber are not in communication. Therefore, according to the above expander, even if the volume of the fluid chamber (suction volume) is changed according to the operating conditions as in the conventional expander, the dead volume is caused by the working fluid remaining in the variable volume chamber. The expansion energy of the working fluid can be recovered efficiently.

  An auxiliary chamber communicating with the fluid chamber is provided, and the volume changing device controls a piston that partitions the auxiliary chamber into the variable volume chamber and a back pressure chamber filled with fluid, and a pressure in the back pressure chamber. And a control device.

  Thus, the variable volume chamber can be formed with a simple configuration. Further, according to the present expander, the volume of the variable volume chamber can be automatically increased or decreased by controlling the pressure in the back pressure chamber.

  The control device is configured such that the pressure in the back pressure chamber when the volume of the variable volume chamber becomes zero or minimum is lower than the pressure of the working fluid sucked into the fluid chamber and is discharged from the fluid chamber. It is preferable to control the pressure higher than the pressure of the working fluid.

  Thus, the volume changing device can automatically change the volume of the fluid chamber while one cycle is performed. Further, the volume of the fluid chamber (suction volume) can be increased without causing a dead volume with a simple configuration.

  It is preferable that a part of the working fluid sucked into the fluid chamber is supplied to the back pressure chamber.

  As a result, it is possible to increase or decrease the volume (suction volume) of the fluid chamber by supplying fluid to the back pressure chamber without providing a separate fluid supply device.

  The auxiliary chamber is provided with a stopper for restricting the piston from moving in a direction opposite to the fluid chamber from a predetermined position, and the stopper is configured to be adjustable in the moving direction of the piston. Preferably it is.

  According to the expander, the stroke amount of the piston can be freely changed. Thus, the additional volume of the fluid chamber by the variable volume chamber can be freely changed. Therefore, the suction volume can be changed freely.

  The volume changing device preferably includes a biasing device that biases the piston toward the fluid chamber.

  This makes it possible to lower the pressure of the fluid in the back pressure chamber than when no elastic body is provided.

  The urging device is preferably a coil spring provided on the back pressure chamber side of the piston.

  This makes it possible to bias the piston with a simple configuration.

  The expander preferably includes a plurality of the volume changing devices.

  According to the expander, for example, the amount of increase in the volume of the fluid chamber (suction volume) can be changed by changing the number of operations of the volume changing device. Therefore, the suction volume can be changed as appropriate according to the operating state. Therefore, advanced control can be performed on the refrigeration cycle apparatus incorporating the expander.

  The expander includes a cylinder having an inner peripheral surface, and a cylindrical piston rotatably disposed in an eccentric state in the cylinder, and the main fluid chamber includes an inner peripheral surface of the cylinder. It is preferable to partition between the outer peripheral surface of the cylindrical piston.

  As a result, it is possible to provide a rotary expander capable of changing the suction volume without causing a dead volume.

  The expander includes a pair of scroll members in which spiral wraps are formed on a flat plate member, the pair of scroll members are arranged so that the laps mesh with each other, and the main fluid chamber includes the pair of scroll members. It is preferable that the scroll member is partitioned between the wraps.

  As a result, it is possible to provide a scroll type expander capable of changing the suction volume without causing a dead volume.

  The working fluid may be carbon dioxide.

  Generally, when carbon dioxide is used as the working fluid of the refrigeration cycle apparatus, the refrigeration efficiency (COP) is lower than that using chlorofluorocarbon or the like as the working fluid. However, according to the expander, the volume (suction volume) of the fluid chamber can be increased / decreased without causing a dead volume, so that the expansion energy of the working fluid can be efficiently recovered. Therefore, when the expander is used, the refrigeration efficiency of the refrigeration cycle apparatus can be maintained high even if carbon dioxide is used as the working fluid.

  An expander-integrated compressor according to the present invention includes a compressor that compresses the working fluid, the expander, and a rotary shaft that connects the compressor and the expander.

  According to the expander-integrated compressor, the expansion energy of the expander can be efficiently recovered and used for compression of the compressor.

  The refrigeration cycle apparatus according to the present invention is guided by the compressor that compresses the working fluid, the expander, a first flow path that guides the working fluid compressed by the compressor, and the first flow path. A heat radiator that radiates the working fluid, a second channel that guides the working fluid from the radiator to the expander, a third channel that guides the working fluid expanded by the expander, and the third channel An evaporator for evaporating the working fluid, and a fourth flow path for guiding the working fluid from the evaporator to the compressor.

  According to the refrigeration cycle apparatus, it is possible to efficiently recover the expansion energy of the working fluid.

  The refrigeration cycle apparatus according to the present invention includes the expander-integrated compressor, a first flow path for guiding a working fluid compressed by the compressor of the expander-integrated compressor, and the first flow path. A radiator for radiating the working fluid, a second flow path for guiding the working fluid from the radiator to the expander of the expander-integrated compressor, and a third flow for guiding the working fluid expanded by the expander A passage, an evaporator for evaporating the working fluid guided by the third flow path, and a fourth flow path for guiding the working fluid from the evaporator to the compressor.

  According to the refrigeration cycle apparatus, it is possible to efficiently recover the expansion energy of the working fluid.

  The refrigeration cycle apparatus according to the present invention includes a pressure sensor that detects the pressure of the working fluid flowing through the first flow path, and the control device of the expander is configured to perform the first operation based on the pressure detected by the pressure sensor. The pressure in the back pressure chamber is controlled so that the pressure of the working fluid flowing through the flow path becomes a predetermined pressure.

  According to the refrigeration cycle apparatus, it is possible to maintain the pressure of the working fluid flowing through the first flow path at a preferable pressure. Thereby, it becomes possible to collect | recover efficiently the expansion energy of a working fluid, and the refrigeration cycle apparatus with sufficient refrigeration efficiency can be provided.

  The refrigeration cycle apparatus according to the present invention includes a temperature sensor that detects a temperature of the working fluid that flows through the first flow path, and the control device of the expander is configured based on the temperature detected by the temperature sensor. The pressure in the back pressure chamber is controlled so that the temperature of the working fluid flowing through the flow path becomes a predetermined temperature.

  According to the refrigeration cycle apparatus, it is possible to maintain the temperature of the working fluid flowing through the first flow path at a preferable temperature. Thereby, it becomes possible to collect | recover efficiently the expansion energy of a working fluid, and the refrigeration cycle apparatus with sufficient refrigeration efficiency can be provided.

  As described above, according to the present invention, in the power recovery type refrigeration cycle apparatus, it is possible to efficiently recover the expansion energy of the working fluid.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a refrigerant circuit 1 of a refrigeration cycle apparatus. A compressor 2, a radiator 3, an expander 4, and an evaporator 5 are sequentially connected to the refrigerant circuit 1. The compressor 2 and the expander 4 of this embodiment are connected by a rotating shaft 6 to constitute an expander-integrated compressor 7. The compressor 2 is connected to the evaporator 5 through the suction pipe 8 and is connected to the radiator 3 through the discharge pipe 9. The expander 4 is connected to the radiator 3 via the suction pipe 10 and is connected to the evaporator 5 via the discharge pipe 11. A pipe 12 branches from the suction pipe 10, and the pipe 12 is connected to the expander 4. A pressure reducing valve 13 for reducing the pressure of the working fluid in the pipe 12 is provided in the middle of the pipe 12, and the pressure reducing valve 13 is controlled to be opened and closed by a control device 14. The discharge pipe 9 is provided with a pressure sensor 15 that detects the pressure of the working fluid discharged from the compressor 2. The pressure sensor 15 is connected to the control device 14.

The refrigerant circuit 1 is filled with a working fluid that becomes a supercritical state in a high-pressure portion (portion from the compressor 2 through the radiator 3 to the expander 4). In the present embodiment, carbon dioxide (CO ₂ ) is filled as such a working fluid. However, the type of working fluid is not particularly limited. The working fluid of the refrigerant circuit 1 may be a working fluid that does not enter a supercritical state during operation (for example, a fluorocarbon working fluid).

  Further, the refrigerant circuit in which the expander-integrated compressor 7 is incorporated is not limited to the refrigerant circuit 1 that allows the working fluid to flow only in one direction. The expander-integrated compressor 7 may be provided in a refrigerant circuit capable of changing the flow direction of the working fluid. For example, the expander-integrated compressor 7 may be provided in a refrigerant circuit capable of heating operation and cooling operation by having a four-way valve or the like.

  As shown in FIG. 2, the compressor 2 and the expander 4 of the expander-integrated compressor 7 are accommodated in a sealed container 50. As described above, the compressor 2 and the expander 4 are connected by the rotary shaft 6, and the electric motor 23 is provided between the compressor 2 and the expander 4.

  First, the configuration of the expander 4 will be described. The expander 4 includes a lower bearing 42, a first expansion portion 30 a, a second expansion portion 30 b, and an upper bearing 41. The 1st expansion part 30a is arrange | positioned below the 2nd expansion part 30b. The upper bearing 41 is disposed above the second expansion portion 30b, and the lower bearing 42 is disposed below the first expansion portion 30a.

  As shown in FIG. 3A, the first expansion portion 30a is a rotary expander, and includes a substantially cylindrical cylinder 31a and a cylindrical piston 32a inserted into the cylinder 31a. . A first fluid chamber 33a is defined between the inner peripheral surface of the cylinder 31a and the outer peripheral surface of the piston 32a. An auxiliary chamber 81 communicating with the first fluid chamber 33a is provided in the cylinder 31a. Further, a vane groove 34c extending radially outward is formed in the cylinder 31a, and the vane 34a is slidably inserted into the vane groove 34c. A back chamber 34h that communicates with the vane groove 34c and extends outward in the radial direction is formed on the back side (radially outside) of the vane 34a of the cylinder 31a. The back chamber 34h is provided with a spring 35a that biases the vane 34a toward the piston 32a. The vane 34a partitions the first fluid chamber 33a into a high pressure side fluid chamber H1 and a low pressure side fluid chamber L1.

  As shown in FIG. 3B, the second inflating portion 30b has substantially the same configuration as the first inflating portion 30a. That is, the second expansion portion 30b is also a rotary expander, and includes a substantially cylindrical cylinder 31b and a cylindrical piston 32b inserted into the cylinder 31b. A second fluid chamber 33b is defined between the inner peripheral surface of the cylinder 31b and the outer peripheral surface of the piston 32b. Also in the cylinder 31b, a vane groove 34d extending outward in the radial direction is formed, and the vane 34b is slidably inserted into the vane groove 34d. Further, a back chamber 34i that communicates with the vane groove 34d and extends radially outward is formed on the back side of the vane 34b of the cylinder 31b. The back chamber 34i is provided with a spring 35b that biases the vane 34b toward the piston 32b. The vane 34b partitions the second fluid chamber 33b into a high pressure side fluid chamber H2 and a low pressure side fluid chamber L2. The second fluid chamber 33b forms the main fluid chamber 33c of the expander 4 together with the first fluid chamber 33a.

  As shown in FIG. 2, the first expansion portion 30 a and the second expansion portion 30 b are partitioned by a partition plate 39. The partition plate 39 covers the upper side of the cylinder 31a and the piston 32a of the first expansion portion 30a, and partitions the upper side of the first fluid chamber 33a. Further, the partition plate 39 covers the lower side of the cylinder 31b and the piston 32b of the second expansion portion 30b, and partitions the lower side of the second fluid chamber 33b.

  The partition plate 39 is formed with a communication hole 40 for communicating the low pressure side fluid chamber L1 of the first fluid chamber 33a and the high pressure side fluid chamber H2 of the second fluid chamber 33b (FIG. 3A). (See (b)). In the present embodiment, the low pressure side fluid chamber L1 of the first fluid chamber 33a and the high pressure side fluid chamber H2 of the second fluid chamber 33b form one expansion chamber through the communication hole 40. That is, after the high-pressure working fluid flows into the high-pressure side fluid chamber H1 of the first fluid chamber 33a, the low-pressure side fluid chamber L1 of the first fluid chamber 33a, the communication hole 40, and the high-pressure side of the second fluid chamber 33b. In the one expansion chamber formed by the fluid chamber H2, the rotary shaft 6 is rotated while being expanded to become a low pressure. Then, the working fluid is eventually discharged from the low pressure side fluid chamber L2 of the second fluid chamber 33b to the discharge pipe 11.

  As shown in FIG. 2, an upper bearing 41 is provided on the upper portion of the second inflating portion 30b. The upper bearing 41 closes the upper side of the cylinder 31b and the piston 32b of the second expansion portion 30b and defines the upper side of the second fluid chamber 33b. Further, the upper bearing 41 is formed with a discharge hole 11a (see FIG. 3B). One end of the discharge pipe 11 is connected to the discharge hole 11a. On the other hand, a lower bearing 42 is provided below the first inflating part 30a. The lower bearing 42 supports the lower end portion of the rotating shaft 6. Further, the lower bearing 42 closes the lower side of the cylinder 31a and the piston 32a of the first expansion portion 30a, and defines the lower side of the first fluid chamber 33a. The lower bearing 42 is formed with a suction hole 10a (see FIG. 3A). One end of the suction pipe 10 is connected to the suction hole 10a.

  Further, as shown in FIG. 3A, the expander 4 is provided with a volume changing device 80 that changes the suction volume of the fluid chamber 37 through which the working fluid flows in the expander 4. Here, the fluid chamber 37 refers to a chamber formed by the main fluid chamber 33c described above and a variable volume chamber 83 described later. The volume changing device 80 includes a piston 84 that partitions an auxiliary chamber 81 provided in the cylinder 31a into a back pressure chamber 82 in which a fluid is sealed and a variable volume chamber 83 that communicates with the first fluid chamber 33a. And a control device 14 for controlling the pressure of the fluid sealed in the container. The piping 12 described above is connected to the back pressure chamber 82, and a part of the working fluid that has flowed out of the radiator 3 is sealed therein. Although the pressure in the back pressure chamber 82 is controlled by the control device 14, specific control will be described later.

  As shown in FIG. 3A, the first fluid chamber 33a side end of the auxiliary chamber 81 is designed to have a smaller diameter than the other end so that the piston 84 does not enter the first fluid chamber 33a. . Further, the first fluid chamber 33a side end portion of the piston 84 is formed in the same shape so as to engage with the first fluid chamber 33a side end portion of the auxiliary chamber 81 without a gap.

  The pressure in the first fluid chamber 33a acts on the end surface of the piston 84 on the first fluid chamber 33a side, and the pressure in the back pressure chamber 82 acts on the other end surface. That is, the position of the piston 84 in the auxiliary chamber 81 is determined by the balance of these pressures. For example, when the pressure in the first fluid chamber 33a is larger than the pressure in the back pressure chamber 82, the piston 84 moves in the direction opposite to the first fluid chamber 33a (hereinafter referred to as the rear). On the other hand, when the pressure in the first fluid chamber 33a is smaller than the pressure in the back pressure chamber 82, the piston 84 moves in the first fluid chamber 33a side direction (hereinafter referred to as the front). The piston 84 stops at a position where the pressure in the first fluid chamber 33a and the pressure in the back pressure chamber 82 are equal, or at the front end portion of the auxiliary chamber 81 or the rear end portion of the auxiliary chamber 81. Therefore, by adjusting the pressure in the back pressure chamber 82 by the control device 14, the volume of the variable volume chamber 83 and thus the volume of the fluid chamber 37 can be changed.

  Next, the configuration of the compressor 2 will be described. In the present embodiment, the compressor 2 is a scroll compressor. The format of the compressor 2 is not limited at all. For example, a rotary compressor or the like can be suitably used as the compressor 2.

  As shown in FIG. 2, the compressor 2 is joined to the sealed container 50 by welding or the like. The compressor 2 includes a fixed scroll 51, a movable scroll 52 that faces the fixed scroll 51 in the axial direction, and a bearing 53 that supports the upper end portion of the rotary shaft 6. The fixed scroll 51 is formed with a wrap 54 having a spiral shape (for example, an involute shape). The movable scroll 52 is formed with a wrap 57 that meshes with the wrap 54 of the fixed scroll 51. A spiral compression chamber 58 is defined between the wrap 54 and the wrap 57. A discharge hole 55 is provided at the center of the fixed scroll 51. An Oldham ring 60 that prevents the rotation of the movable scroll 52 is disposed below the movable scroll 52. The upper end portion of the rotating shaft 6 is eccentric, and the movable scroll 52 is supported on the eccentric upper end portion of the rotating shaft 6. Therefore, the movable scroll 52 turns in a state of being eccentric from the axis of the rotary shaft 6.

  A cover 62 is provided on the upper side of the fixed scroll 51. Inside the fixed scroll 51 and the bearing 53, there is formed a discharge passage 61 extending vertically to allow the working fluid to flow. Further, on the outside of the fixed scroll 51 and the bearing 53, a flow passage 63 extending in the vertical direction for flowing the working fluid is formed. With such a configuration, the working fluid discharged from the discharge hole 55 is once discharged into the space in the cover 62 and then discharged to the lower side of the compressor 2 through the discharge path 61. The working fluid below the compressor 2 is guided to the upper side of the compressor 2 through the flow passage 63.

  The suction pipe 8 passes through the side portion of the sealed container 50 and is connected to the fixed scroll 51. Thereby, the suction pipe 8 is connected to the suction side of the compressor 2. The discharge pipe 9 is connected to the upper part of the sealed container 50. One end of the discharge pipe 9 opens into a space above the compressor 2 in the sealed container 50.

  The electric motor 23 includes a rotor 71 fixed to the middle portion of the rotating shaft 6 and a stator 72 disposed on the outer peripheral side of the rotor 71. The stator 72 is fixed to the inner wall of the side portion of the sealed container 50. The stator 72 is connected to a terminal (not shown) via a motor wiring (not shown). The rotating shaft 6 is driven by the electric motor 23.

  Next, the operation of the expander-integrated compressor 7 will be described. In the expander-integrated compressor 7, when the electric motor 23 is driven, the rotary shaft 6 rotates.

  The operation of the compressor 2 will be described. First, the movable scroll 52 turns with the rotation of the rotary shaft 6. Thereby, the refrigerant is sucked from the suction pipe 8. The sucked low-pressure refrigerant is compressed in the compression chamber 58 and then discharged from the discharge hole 55 as a high-pressure refrigerant. Then, the refrigerant discharged from the discharge hole 55 is guided to the upper side of the compressor 2 through the discharge passage 61 and the flow passage 63 and is discharged to the outside of the sealed container 50 through the discharge pipe 9.

  Next, the operation of the expander 4 will be described. First, the pistons 32a and 32b rotate according to the rotation of the rotating shaft 6. Thereby, the high-pressure refrigerant sucked from the suction pipe 10 flows into the first fluid chamber 33a through the suction hole 10a. The high-pressure refrigerant flowing into the first fluid chamber 33a is one expansion formed by the fluid chamber L1 on the low-pressure side of the first fluid chamber 33a, the communication hole 40, and the fluid chamber H2 on the high-pressure side of the second fluid chamber 33b. It expands indoors and becomes a low-pressure refrigerant. At that time, the working fluid expands while rotating the rotating shaft 6. The low-pressure refrigerant flows into the discharge pipe 11 through the discharge hole 11 a and is discharged to the outside of the sealed container 50 through the discharge pipe 11. Hereinafter, the operations of the expander 4 and the volume changing device 80 in one cycle will be described in detail with reference to FIG.

  The expander 4 performs one cycle from the suction process to the discharge process while the rotary shaft 6 rotates three times (performed in the order of the suction process, the expansion process, and the discharge process). For convenience of explanation, the rotation angle θ in a state where the pistons 32a and 32b are in contact with the cylinders 31a and 31b is expressed as θ = (0 + 360n) ° using an integer n (n = 0, 1, 2).

  As shown in FIG. 4A, the cycle starts from θ = 0 ° in the first round. When the contact point between the cylinder 31a and the piston 32a passes through the suction hole 10a, the high pressure side fluid chamber H1 and the suction hole 10a communicate with each other, and the suction process starts (see FIG. 4B).

  When the rotating shaft 6 further rotates, the contact point between the cylinder 31 a and the piston 32 a passes through the auxiliary chamber 81. As a result, the auxiliary chamber 81 communicates with the fluid chamber H1 on the high pressure side (see FIG. 4D). Therefore, the pressure in the fluid chamber H1 on the high pressure side of the first fluid chamber 33a acts on the end surface of the piston 84 on the first fluid chamber 33a side. On the other hand, the pressure in the back pressure chamber 82 acts on the other end face of the piston 84 at this time. In the back pressure chamber 82, the pressure in the back pressure chamber 82 is lower than the pressure of the working fluid (working fluid in the high pressure side fluid chamber H1) sucked into the first fluid chamber 33a by the control device 14, And the fluid is enclosed so that it may become higher than the pressure of the working fluid discharged from the 2nd fluid chamber 33b. Therefore, the piston 84 starts moving backward. As a result, the variable volume chamber 83 is generated, and the suction volume of the fluid chamber 37 is increased.

  The piston 84 that has started to move rearward stops moving at a position where the pressure in the fluid chamber H1 on the high pressure side and the pressure in the back pressure chamber 82 are balanced. Further, even if the piston 84 moves rearward, the piston 84 moves to the rear end portion of the auxiliary chamber 81 when the pressure in the high pressure side fluid chamber H <b> 1 remains higher than the pressure in the back pressure chamber 82. (Not shown).

  The volume of the fluid chamber H1 on the high pressure side further increases as the rotation angle θ increases. After θ = 360 ° and the second round (n = 1) is started, the communication between the suction hole 10a and the low-pressure side fluid chamber L1 is cut off, and the suction process ends. At the same time, the high pressure side fluid chamber H1 becomes the low pressure side fluid chamber L1 (see FIG. 4B). The low pressure side fluid chamber L1 communicates with the high pressure side fluid chamber H2 of the second fluid chamber 33b through the communication hole 40 to form one expansion chamber. This starts the expansion process (see FIG. 4B).

  When the rotating shaft 6 further rotates, the volume of the fluid chamber L1 on the low pressure side of the first fluid chamber 33a decreases. However, since the cylinder 31b has a larger volume than the cylinder 31a (see FIG. 2), the volume of the fluid chamber H1 on the high pressure side of the second fluid chamber 33b is larger than the rate of decrease of the volume of the fluid chamber L1 on the low pressure side. Increase with. As a result, the volume of the expansion chamber formed by the low pressure side fluid chamber L1, the communication hole 40, and the high pressure side fluid chamber H2 increases, and the working fluid in the expansion chamber expands. In this manner, the pressure in the expansion chamber formed by the low-pressure side fluid chamber L1, the communication hole 40, and the high-pressure side fluid chamber H2 decreases (see FIG. 4B).

  When the pressure in the expansion chamber formed by the low pressure side fluid chamber L1, the communication hole 40, and the high pressure side fluid chamber H2 decreases and becomes lower than the pressure in the back pressure chamber 82, the piston 84 starts moving forward. To do. As a result, the variable volume chamber 83 generated during the suction process is reduced. As the rotation shaft 6 rotates, the pressure in the expansion chamber further decreases, so that the piston 84 continues to move forward until reaching the front end of the auxiliary chamber 81 (hereinafter referred to as top dead center), and eventually the variable volume. The chamber 83 disappears, and the volume of the variable volume chamber 83 becomes zero (see FIG. 4C).

  When the contact point between the cylinder 31a and the piston 32a passes through the auxiliary chamber 81, the communication between the auxiliary chamber 81 and the low-pressure side fluid chamber L1 is cut off. The auxiliary chamber 81 communicates with the next fluid chamber H1 on the high pressure side (see FIG. 4D).

  When the rotating shaft 6 further rotates and approaches θ = 720 °, the contact point between the cylinder 31a and the piston 32a passes through the communication hole 40, and the low pressure side fluid chamber L1 of the first fluid chamber 33a disappears. At this time, in the second expansion portion 30b, the contact point between the cylinder 31b and the piston 32b passes through the discharge hole 11a. At this point, the expansion process ends. Then, the fluid chamber H2 on the high pressure side of the second fluid chamber 33b communicates with the discharge hole 11a, and the discharge process is started.

  At θ = 720 ° starting from the third week (n = 2), the high pressure side fluid chamber H2 of the second fluid chamber 33b becomes the low pressure side fluid chamber L2. As the rotating shaft 6 further rotates, the volume of the fluid chamber L2 decreases, and the working fluid is discharged from the discharge hole 11a. Eventually, at θ = 1080 °, the fluid chamber L2 disappears, and the discharge process ends.

  Thus, during the suction process, when the variable volume chamber 83 and the first fluid chamber 33a change from the non-communication state to the communication state, due to the pressure difference between the first fluid chamber 33a and the back pressure chamber 82, The volume of the variable volume chamber 83 increases from zero. When the expansion process is started, the volume of the variable volume chamber 83 decreases due to the pressure difference in the first fluid chamber 33a and the pressure in the back pressure chamber 82, and eventually becomes zero. Then, after the volume of the variable volume chamber 83 becomes zero, the variable volume chamber 83 and the first fluid chamber 33a change from the communication state to the non-communication state.

  Next, control of the control device 14 will be described.

  The control device 14 sets the pressure in the back pressure chamber 82 when the volume of the variable volume chamber 83 becomes zero lower than the pressure of the working fluid sucked into the first fluid chamber 33a and from the second fluid chamber 33b. The pressure is controlled to be higher than the pressure of the discharged working fluid. Further, the control device 14 controls the pressure of the working fluid in the back pressure chamber 82 based on the detected pressure from the pressure sensor 15 so that the pressure of the working fluid discharged from the compressor 2 becomes a predetermined target value. . As a result, the pressure in the back pressure chamber 82 is adjusted by the control device 14, and the piston 84 moves in the auxiliary chamber 81, and the bottom dead center of the piston 84 in the auxiliary chamber 81 (in the auxiliary chamber 81, the first The position farthest from the fluid chamber 33a) is changed. Therefore, when the control device 14 controls the pressure in the back pressure chamber 82, the stroke amount (distance between the top dead center and the bottom dead center) of the piston 84 is changed, and the maximum volume (fluid chamber) of the variable volume chamber 83 is changed. 37 additional volume) will be changed.

  Specifically, when the detected value is lower than the target value (when the pressure of the refrigerant discharged from the compressor 2 is lower than the target value), the refrigerant passes through the expander 4 with respect to the mass flow rate of the refrigerant passing through the compressor 2. The mass flow rate of the refrigerant is relatively excessive, and so-called expansion is insufficient. Therefore, the control device 14 further sends a fluid into the back pressure chamber 82 to increase the pressure in the back pressure chamber 82. Thereby, the bottom dead center of the piston 84 approaches the front end side of the auxiliary chamber 81, and the stroke amount of the piston becomes small. That is, the maximum volume of the variable volume chamber 83 is reduced to reduce the refrigerant suction amount, thereby avoiding insufficient expansion.

  On the other hand, when the detected value is higher than the target value (when the pressure of the refrigerant discharged from the compressor 2 is higher than the target value), the refrigerant flowing through the expander 4 with respect to the mass flow rate of the refrigerant passing through the compressor 2 The mass flow rate becomes relatively small and so-called overexpansion occurs. Therefore, the control device 14 discharges the fluid from the back pressure chamber 82 and reduces the pressure in the back pressure chamber 82. As a result, the bottom dead center of the piston 84 approaches the rear end side of the auxiliary chamber 81, and the stroke amount of the piston increases. That is, the maximum volume of the variable volume chamber 83 is increased to increase the amount of refrigerant sucked to avoid overexpansion.

  As described above, according to the expander 4 according to this embodiment, the volume changing device 80 can increase or decrease the volume of the variable volume chamber 83 and increase or decrease the suction volume of the fluid chamber 37. Thereby, overexpansion and underexpansion can be avoided. As a result, the system can be optimally operated and the system efficiency can be improved.

  Further, according to the present expander 4, unlike the conventional case, the variable volume chamber 83 does not always exist while the expander 4 performs one cycle, and the volume of the variable volume chamber 83 increases or decreases during one cycle. . That is, the variable volume chamber 83 of the present expander 4 is generated when the variable volume chamber 83 and the first fluid chamber 33a communicate with each other during the suction process, and the variable volume chamber 83 and the first fluid chamber 33a are connected during the expansion process. It disappears before it becomes out of communication. Therefore, it is possible to prevent the working fluid from remaining in the variable volume chamber 83 when the variable volume chamber 83 and the first fluid chamber 33a are not in communication. Therefore, according to the expander 4, unlike the conventional expander, even if the suction volume of the fluid chamber 37 is changed according to the operating conditions, the variable volume chamber 83 disappears during the expansion process. Does not become a dead volume, and the expansion energy of the working fluid can be efficiently recovered.

  In the present embodiment, the volume of the variable volume chamber 83 becomes zero before the variable volume chamber 83 and the first fluid chamber 33a are disconnected from each other during the expansion process. However, according to the present expander 4, even when the volume of the variable volume chamber 83 does not become zero, the variable volume chamber 83 becomes a dead volume by minimizing the volume of the variable volume chamber 83. Can be suppressed. Therefore, even in such a case, the expansion energy of the working fluid can be efficiently recovered.

  Furthermore, in the present expander 4, the pressure in the back pressure chamber 82 when the volume of the variable volume chamber 83 becomes zero is lower than the pressure of the working fluid sucked into the first fluid chamber 33a by the control device 14. In addition, the pressure is controlled to be higher than the pressure of the working fluid discharged from the second fluid chamber 33b. Therefore, the variable volume chamber 83 is automatically generated during the suction process due to the differential pressure between the back pressure chamber 82 and the first fluid chamber 33a, and decreases and disappears during the expansion process. Therefore, according to the present expander 4, the suction volume of the fluid chamber 37 can be increased or decreased with a simple configuration without causing a dead volume.

  A part of the working fluid sucked into the first fluid chamber 33a is supplied to the back pressure chamber 82 of the present expander 4. Therefore, the fluid can be supplied to the back pressure chamber 82 without providing a separate fluid supply device. As shown in FIG. 5, it is of course possible to newly provide a fluid supply device 90 and supply the fluid to the back pressure chamber 82.

Furthermore, the refrigerant circuit 1 including the present expander 4 is filled with carbon dioxide (CO ₂ ) that becomes a supercritical state in a high-pressure portion (portion from the compressor 2 through the radiator 3 to the expander 4). . In general, when carbon dioxide is used as the working fluid of the refrigeration cycle apparatus, the refrigeration efficiency (COP) is lower than that using chlorofluorocarbon as the working fluid. However, according to the present expander 4, since the suction volume of the fluid chamber 37 can be increased or decreased without causing a dead volume, the expansion energy of the working fluid can be efficiently recovered. Therefore, according to the refrigeration cycle apparatus provided with the present expander 4, it is possible to maintain high refrigeration efficiency even when carbon dioxide is used as the working fluid.

  The control device 14 of the refrigeration cycle apparatus is configured to control the working fluid in the back pressure chamber 82 based on the detected pressure from the pressure sensor 15 so that the pressure of the working fluid discharged from the compressor 2 becomes a predetermined target value. Control the pressure. Therefore, according to the present refrigeration cycle apparatus, the pressure of the working fluid discharged from the compressor 2 can be maintained at a preferable pressure. As a result, overexpansion and underexpansion of the expander 4 can be prevented, and the expansion energy of the working fluid can be efficiently recovered.

(Second Embodiment)
In the first embodiment, the stroke amount of the piston 84 of the expander 4 is changed based on the pressure of the working fluid discharged from the compressor 2. Instead, in this embodiment, the stroke amount of the piston 84 of the expander 4 is changed based on the temperature of the working fluid discharged from the compressor 2.

  Specifically, as shown in FIG. 6, a temperature sensor 16 that detects the temperature of the working fluid discharged from the compressor 2 is provided in the discharge pipe 9 instead of the pressure sensor 15. Then, the control device 14 controls the pressure in the back pressure chamber 82 based on the detected pressure from the temperature sensor 16 so that the temperature of the working fluid discharged from the compressor 2 becomes a predetermined target value. To do.

  When control is performed so that the temperature of the working fluid discharged from the compressor 2 is maintained at a target value, the pressure of the working fluid is also maintained at a predetermined value. That is, in the refrigeration cycle apparatus, the pressure of the discharge fluid can be controlled by controlling the temperature of the discharge fluid of the compressor 2. Therefore, the present embodiment can provide the same effects as those of the first embodiment.

(Third embodiment)
In the first embodiment, the bottom dead center of the piston 84 (the stroke amount of the piston 84) is determined by controlling the pressure in the back pressure chamber 82. In this embodiment, instead of controlling the pressure in the back pressure chamber 82, the bottom dead center is determined using a regulating member that regulates the movement of the piston 84, and the suction volume of the fluid chamber 37 is changed.

  For example, as shown in FIG. 7, a movable stopper 85 that restricts the movement of the piston 84 is provided in the auxiliary chamber 81. The stopper 85 is configured to be capable of changing the position in the auxiliary chamber 81 with respect to the moving direction of the piston 84. Further, a driving device 86 for driving the stopper 85 is provided, and the driving device 86 is controlled by the control device 14. Based on the detected pressure from the pressure sensor 15, the control device 14 controls the operation amount of the drive device 86 so that the pressure of the working fluid discharged from the compressor 2 becomes a predetermined target value, and the position of the stopper 85 is set. change.

  As described above, the present embodiment can provide the same effects as those described above. Further, according to this embodiment, the bottom dead center of the piston 84 can be determined not by the pressure difference between the first fluid chamber 33a and the back pressure chamber 82, but by the position of the stopper 85. Therefore, the maximum volume of the variable volume chamber 83 can be increased or decreased accurately. Thereby, the suction volume of the fluid chamber 37 can be increased or decreased accurately, and the expansion energy of the working fluid can be efficiently recovered.

  The shape of the stopper 85 is not limited as long as the stopper 85 can change the position without partitioning the back pressure chamber 82 and can restrict the movement of the piston 84.

(Fourth embodiment)
In the first embodiment, the pressure in the first fluid chamber 33a acts on the front end surface of the piston 84, and the pressure in the back pressure chamber 82 acts on the rear end surface. The position of the piston 84 in the chamber 81 was fixed. In the present embodiment, as shown in FIG. 8, in addition to the configuration of the first embodiment, a coil spring 84a as a biasing device that biases the piston 84 forward is provided in the back pressure chamber 82. . The coil spring 84 a is disposed in a compressed state in the back pressure chamber 82, and one end of the coil spring 84 a is supported in the back pressure chamber 82 and the other end is supported on the rear end surface of the piston 84.

  With such a configuration, the pressure in the back pressure chamber 82 and the urging force of the coil spring 84a act on the rear end surface of the piston 84. Therefore, the position of the piston 84 in the auxiliary chamber 81 is determined by the balance between the pressure in the first fluid chamber 33a and the sum of the pressure in the back pressure chamber 82 and the biasing force of the coil spring 84a. For example, when the pressure in the first fluid chamber 33a is larger than the sum of the pressure in the back pressure chamber 82 and the urging force of the coil spring 84a, the piston 84 moves rearward. On the other hand, when the pressure in the first fluid chamber 33a is smaller than the sum of the pressure in the back pressure chamber 82 and the urging force of the coil spring 84a, the piston 84 moves forward. The piston 84 has a position where the pressure in the first fluid chamber 33a is equal to the sum of the pressure in the back pressure chamber 82 and the biasing force of the coil spring 84a, or the front end of the auxiliary chamber 81 or the auxiliary chamber 81. It will stop at the rear end of.

  Further, the control device 14 according to the present embodiment uses the pressure in the back pressure chamber 82 as the sum of the pressure in the back pressure chamber 82 when the volume of the variable volume chamber 83 becomes zero and the biasing force of the coil spring 84a. Is controlled to be lower than the pressure of the working fluid sucked into the first fluid chamber 33a and higher than the pressure of the working fluid discharged from the second fluid chamber 33b. Thereby, also by the expander 4 which concerns on this embodiment, there can exist an effect similar to 1st Embodiment. Further, according to the present expander 4, it is possible to lower the pressure of the fluid in the back pressure chamber 82 than when no elastic body such as the coil spring 84a is provided.

  In the present embodiment, the coil spring 84a is used as the biasing device that biases the piston 84, but the biasing device may be an elastic body other than the coil spring 84a. Further, the urging device is not limited to an elastic body, and may generate an urging force by, for example, electrostatic force or magnetic force.

(Fifth embodiment)
In the first embodiment, only one volume changing device 80 is provided. As shown in FIG. 9, the expander 4 according to this embodiment is provided with a plurality of the volume changing devices 80. FIG. 9 shows a case where two volume changing devices 80 having different volumes because of different inner diameters are provided. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  The expander 4 according to this embodiment can achieve the same effects as those of the first embodiment. Further, according to the present embodiment, the maximum value of the volume of the variable volume chamber 83 can be easily changed by selecting which volume changing device 80 is used. That is, the suction volume of the fluid chamber 37 can be easily changed.

  A plurality of volume changing devices 80 having the same volume may be provided. In this case, the maximum value of the volume of the variable volume chamber 83 (the sum of the plurality of variable volume chambers 83) can be easily changed by increasing or decreasing the number of volume changing devices 80 to be operated. According to such an embodiment, when the suction volume of the fluid chamber 37 is changed, fine adjustment can be performed, so that controllability can be improved.

  Further, as in the volume changing device 80 (fixed stroke type) as in the first embodiment and the volume changing device 80 as in the third embodiment, the volume of the variable volume chamber 83 is reduced by a movable stopper 85. Of course, it is also possible to use in combination with a volume changing device 80 (variable stroke type) capable of changing the maximum value.

  In such a case, first, the variable stroke type volume changing device 80 is used alone, and the differential pressure control for changing the bottom dead center of the piston 84 by the pressure control in the back pressure chamber 82 is performed. And when the range of differential pressure control is exceeded (for example, when the pressure in the first fluid chamber 33a exceeds the range assumed as the pressure in the back pressure chamber 82), the fixed stroke type is operated. . And it controls again with a variable stroke. According to such a form, the range of the pressure in the first fluid chamber 33a in which differential pressure control is possible is widened, and controllability can be improved.

(Sixth embodiment)
In the first embodiment, the auxiliary chamber 81 is provided in the cylinder 31a so as to extend laterally. On the other hand, in this embodiment, as conceptually shown in FIG. 10, the auxiliary chamber 81 is provided below the cylinder 31a, and the lower bearing 42 that defines the lower side of the first fluid chamber 33a (see FIG. 2). Is provided inside. Further, the auxiliary chamber 81 according to the present embodiment is provided so as to extend in the vertical direction. Other configurations are the same as those of the first embodiment.

  Even if the auxiliary chamber 81 is arranged so as to extend in the vertical direction in the lower bearing 42 as in the present embodiment, the same effect as in the first embodiment can be obtained.

  In the present embodiment, the diameter of the communication hole 81a that communicates the first fluid chamber 33a and the auxiliary chamber 81 is formed larger than the maximum width of the first fluid chamber 33a. When the communication hole 81a is formed in this way, a part of the communication hole 81a always overlaps a part of the piston 32a (see FIG. 10A). Therefore, when the piston 84 of the volume changing device 80 according to the present embodiment moves to the communication hole 81a, the piston 84a always comes into contact with the piston 32a, and further movement is restricted by the piston 32a (see FIG. 10B).

  Therefore, according to the expander 4 of the present embodiment, the piston 84 can be used without designing the end of the auxiliary chamber 81 on the first fluid chamber 33a side to have a smaller diameter than the other end as in the first embodiment. Can be prevented from entering the first fluid chamber 33a. Accordingly, it is not necessary to form the end portion of the piston 84 on the first fluid chamber 33a side in the same shape as the end portion of the auxiliary chamber 81 on the first fluid chamber 33a side. Therefore, according to this embodiment, the trouble of processing the auxiliary chamber 81 and the piston 84 can be saved and can be easily manufactured.

(Seventh embodiment)
The expander 4 of the first embodiment is a so-called rotary expander having two upper and lower stages. As shown in FIG. 11, in the expander-integrated compressor 7 according to the present embodiment, a scroll type expander is used instead of the rotary type expander.

  Specifically, the expander 4 includes a fixed scroll 91 and a movable scroll 92 that faces the fixed scroll 91 in the axial direction. The fixed scroll 91 includes a flat fixed end plate (not shown) and a spiral wrap (for example, an involute shape) wrap 94 provided on one surface of the fixed end plate. On the other hand, the movable scroll 92 includes a flat movable end plate (not shown) and a wrap 97 provided on one surface of the movable end plate and meshing with the wrap 94 of the fixed scroll 91. A spiral fluid chamber 98 is defined between the wrap 94 and the wrap 97.

  A suction hole 95 is provided at the center of the fixed scroll 91. A discharge hole 99 is provided at the end of the fluid chamber 98 on the winding end side. Although not shown, the suction hole 95 is connected to the suction pipe 10, and the discharge hole 99 is connected to the discharge pipe 11. The movable scroll 92 is supported by an eccentric portion provided at the lower end portion of the rotating shaft 6 (see FIG. 2). Therefore, the movable scroll 92 turns in a state of being eccentric from the axis of the rotary shaft 6.

  The fixed scroll 91 is provided with communication holes 81a and 81b. Also in this embodiment, the auxiliary chamber 81 similar to the auxiliary chamber 81 according to the sixth embodiment is connected to the lower bearing 42. The communication holes 81a and 81b are connected to the auxiliary chamber 81 so as to be able to communicate therewith. As in the first embodiment, the auxiliary chamber 81 communicates with the communication holes 81a and 81b during the suction process, and the communication is released at the end of the expansion process.

  Even in such a form, the volume of the variable volume chamber 83 of the auxiliary chamber 81 can be controlled as in the first embodiment, and overexpansion and underexpansion can be avoided. Moreover, also by this embodiment, there can exist an effect similar to the refrigerant circuit 1 which concerns on 1st Embodiment.

(Eighth embodiment)
As shown in FIG. 12, the refrigeration cycle apparatus according to the present embodiment includes a separate compressor 2b instead of the expander-integrated compressor 7 of the refrigeration cycle apparatus according to the first embodiment shown in FIG. The expander 4b is used. The expander 4b has the same configuration as the expander 4 according to the first embodiment.

  The refrigerant circuit 1 of the refrigeration cycle apparatus according to the present embodiment includes the above-described separate compressor 2b and the expander 4b, and the rotating shaft 17 instead of the expander-integrated compressor 7 according to the first embodiment. And an electric generator 23b connected to the expander 4b via the rotary shaft 18. The compressor 2b is driven by the electric motor 23b, and the expansion energy of the working fluid is converted into electric energy by the generator 19 in the expander 4b. This electric energy is used as part of the input of the electric motor 23b.

  Incidentally, the generator 19 is generally designed so that the power generation efficiency is the highest at a predetermined rated rotational speed. For this reason, the power generation efficiency decreases as the rotational speed of the rotary shaft 18 increases from the rated rotational speed. Thereby, it is preferable that the rotational speed of the generator 19 be as close to the rated rotational speed as possible. However, in the refrigeration cycle apparatus, the circulation amount and density of the working fluid change depending on operating conditions and the like. Therefore, in an expander with a constant suction volume, it is difficult to keep the rotational speed of the generator 19 close to the rated rotational speed.

  However, according to the refrigeration cycle apparatus according to the present embodiment, the expander 4b having the same configuration as the expander 4 according to the first embodiment is used. Therefore, the suction volume of the fluid chamber 37 can be adjusted by changing the volume of the variable volume chamber 83 of the volume changing device 80. Therefore, according to the refrigeration cycle apparatus according to the present embodiment, the rotational speed of the generator 19 can be controlled near the rated rotational speed, and the expansion energy can be efficiently recovered.

  As described above, the present invention is useful for an expander, an expander-integrated compressor, and a refrigeration cycle apparatus (a refrigeration apparatus, an air conditioner, a water heater, etc.) using the expander.

Refrigerant circuit diagram of refrigerant circuit The longitudinal cross-sectional view of the expander which concerns on 1st Embodiment (A) is a sectional view taken along line IIIa-IIIa in FIG. 2, and (b) is a sectional view taken along line IIIb-IIIb in FIG. Operational diagram of the expander according to the first embodiment Refrigerant circuit diagram of refrigeration cycle apparatus according to modification Refrigerant circuit diagram of the refrigeration cycle apparatus according to the second embodiment Cross-sectional view of an expander according to a third embodiment Cross-sectional view of an expander according to the fourth embodiment Cross-sectional view of an expander according to a fifth embodiment (A) And (b) is a cross-sectional view of the expander according to the sixth embodiment (A) And (b) is a cross-sectional view of the expander based on 7th Embodiment Refrigerant circuit diagram of the refrigeration cycle apparatus according to the eighth embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerant circuit 2 Compressor 3 Radiator 4 Expander 5 Evaporator 6 Rotating shaft 7 Expander-integrated compressor 8 Suction pipe (first flow path)
9 Discharge pipe (second flow path)
10 Suction pipe (third flow path)
11 Discharge pipe (fourth flow path)
12 piping 13 pressure reducing valve 14 control device 15 pressure sensor 16 temperature sensor 31a, 31b cylinder 32a, 31b piston (cylindrical piston)
33a First fluid chamber (fluid chamber, main fluid chamber)
33b Second fluid chamber (fluid chamber, main fluid chamber)
33c Main fluid chamber 80 Volume change device 81 Auxiliary chamber 82 Back pressure chamber 83 Variable volume chamber (fluid chamber, variable volume chamber)
84 Piston 85 Stopper

Claims (18)

An expander used in a refrigeration cycle apparatus,
A fluid chamber for circulating a working fluid;
A volume changing device capable of changing the suction volume of the fluid chamber,
The volume changing device includes a suction process for sucking the working fluid into the fluid chamber, an expansion process for expanding the sucked working fluid, and a discharge process for discharging the expanded working fluid to the outside of the fluid chamber. An expander that increases or decreases the volume of the fluid chamber during a cycle. The fluid chamber includes a main fluid chamber and a variable volume chamber configured to communicate with the main fluid chamber,
The expander according to claim 1, wherein the variable volume chamber increases in volume during the suction process and decreases to zero or minimum during the expansion process or the discharge process. The fluid chamber includes a main fluid chamber and a variable volume chamber configured to communicate with the main fluid chamber,
The variable volume chamber is
During the inhalation process, the volume increases in communication with the main fluid chamber,
During the expansion process, after the volume is reduced while communicating with the main fluid chamber, the volume becomes zero or minimum before the main fluid chamber is not in communication with the main fluid chamber,
Maintaining a non-communication state with the main fluid chamber during the discharge process;
The expander according to claim 1. An auxiliary chamber communicating with the fluid chamber;
The volume changing device is
A piston that partitions the auxiliary chamber into the variable volume chamber and a back pressure chamber filled with fluid;
A control device for controlling the pressure in the back pressure chamber;
The expander according to claim 2, comprising:   The control device is configured such that the pressure in the back pressure chamber when the volume of the variable volume chamber becomes zero or minimum is lower than the pressure of the working fluid sucked into the fluid chamber and is discharged from the fluid chamber. The expander of Claim 4 controlled to the pressure higher than the pressure of a working fluid.   The expander according to claim 4 or 5, wherein a part of the working fluid sucked into the fluid chamber is supplied to the back pressure chamber. The auxiliary chamber is provided with a stopper for restricting the piston from moving in a direction opposite to the fluid chamber from a predetermined position.
The expander according to any one of claims 4 to 6, wherein the stopper is configured to be adjustable in a moving direction of the piston.   The expander according to any one of claims 4 to 7, wherein the volume changing device includes a biasing device that biases the piston toward the fluid chamber.   The expander according to claim 8, wherein the urging device is a coil spring provided on the back pressure chamber side of the piston.   The expander according to any one of claims 1 to 9, comprising a plurality of the volume changing devices. A cylinder having an inner peripheral surface;
A cylindrical piston rotatably arranged in an eccentric state in the cylinder,
The expander according to any one of claims 2 to 10, wherein the main fluid chamber is partitioned between an inner peripheral surface of the cylinder and an outer peripheral surface of the cylindrical piston. A pair of scroll members in which spiral wraps are formed on the flat plate member;
The pair of scroll members are arranged so that their laps mesh with each other,
The expander according to any one of claims 2 to 10, wherein the main fluid chamber is defined between laps of the pair of scroll members.   The expander according to any one of claims 1 to 12, wherein the working fluid is carbon dioxide. A compressor for compressing the working fluid;
An expander according to any one of claims 1 to 13,
An expander-integrated compressor comprising: a rotary shaft that connects the compressor and the expander. A compressor for compressing the working fluid;
An expander according to any one of claims 4 to 13,
A first flow path for guiding the working fluid compressed by the compressor;
A radiator that radiates the working fluid guided by the first flow path;
A second flow path for guiding a working fluid from the radiator to the expander;
A third flow path for guiding the working fluid expanded by the expander;
An evaporator for evaporating the working fluid guided by the third flow path;
A fourth flow path for leading a working fluid from the evaporator to the compressor;
A refrigeration cycle apparatus comprising: An expander-integrated compressor according to claim 14,
A first flow path for guiding the working fluid compressed by the compressor of the expander-integrated compressor;
A radiator that radiates the working fluid guided by the first flow path;
A second flow path for guiding a working fluid from the radiator to the expander of the expander-integrated compressor;
A third flow path for guiding the working fluid expanded by the expander;
An evaporator for evaporating the working fluid guided by the third flow path;
A fourth flow path for leading a working fluid from the evaporator to the compressor;
A refrigeration cycle apparatus comprising: A pressure sensor for detecting the pressure of the working fluid flowing through the first flow path;
The control device of the expander controls the pressure in the back pressure chamber based on the pressure detected by the pressure sensor so that the pressure of the working fluid flowing through the first flow path becomes a predetermined pressure. Item 16. The refrigeration cycle apparatus according to Item 15. A temperature sensor for detecting the temperature of the working fluid flowing through the first flow path;
The said control apparatus of the said expander controls the pressure in the said back pressure chamber so that the temperature of the working fluid which flows through the said 1st flow path may become predetermined | prescribed temperature based on the temperature which the said temperature sensor detects. Item 16. The refrigeration cycle apparatus according to Item 15.

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