JP2008134024A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle device capable of keeping high power recovering efficiency of an expander even when an operating condition is changed. <P>SOLUTION: This refrigerating cycle device 300A comprises a main refrigerant circuit 301 including a main pipe 330 for successively connecting a compressing mechanism 120, a radiator 310, an expanding mechanism 130, an evaporator 320 and their elements, and a bypass circuit 302 for bypassing a part of the refrigerant after compressed by the compressing mechanism 120 before radiating the heat by the radiator 310 to the neighborhood of the expanding mechanism 130 without flowing into the radiator 310, and joining it with the refrigerant after radiating the heat by the radiator 310 before expanded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus including an expander.

  In recent years, research and development relating to energy saving of refrigeration cycle apparatuses used in water heaters and air conditioners have been actively conducted in response to the seriousness of resource problems and global warming problems. The conventional refrigeration cycle system has a mechanism that expands the refrigerant with an expansion valve. By using an expander instead of the expansion valve, the expansion energy of the refrigerant is recovered with the expander, and the recovered energy is compressed. Attempts have been made to use it as auxiliary power for aircraft. For example, Patent Literature 1 discloses an air conditioner using a so-called expander-integrated compressor in which a compressor and an expander are connected by a shaft.

  Usually, in the refrigeration cycle apparatus, the pressure and temperature of the refrigerant at the inlet of the compressor or expander change with changes in operating conditions (for example, changes in the temperature of water or air to be heat-exchanged). The density of refrigerant flowing into each of the machines also changes.

Therefore, as in the expander-integrated compressor disclosed in Patent Document 1, when the rotation speeds of the compressor and the expander are always equal and the volumes of the compressor and the expander are constant, the compressor and the expander There is an unbalance in the volume flow rate of the refrigerant in each of the machines, the power recovery amount for the compression work is reduced, and the coefficient of performance may even be reduced. In order to avoid this problem, in the air conditioner of Patent Document 1, a bypass path having a flow rate adjustment valve is provided in parallel to the expander.
JP 2001-116371 A

  If a bypass path is provided in parallel to the expander, the volume flow rate of the refrigerant flowing into the expander can be freely changed, so that the volume flow unbalance can be eliminated. However, in order to change the volume flow rate widely, it is necessary to flow a considerable amount of refrigerant through the bypass circuit. As the proportion of the refrigerant flowing through the bypass circuit increases, the power recovery efficiency in the expander decreases, and the effect of improving the coefficient of performance cannot be expected.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a refrigeration cycle apparatus capable of maintaining high power recovery efficiency of an expander even when operating conditions change. There is to do.

That is, the present invention
A compressor for compressing the refrigerant;
A radiator that dissipates the refrigerant compressed by the compressor;
An expander that expands the refrigerant radiated by the radiator;
An evaporator for evaporating the refrigerant expanded by the expander;
Before expansion, a part of the refrigerant compressed by the compressor and radiated by the radiator is bypassed to the path from the radiator to the expander or the expander without flowing into the radiator and radiated by the radiator The bypass circuit has a start end connected to the path from the compressor or compressor to the radiator and a terminal end connected to the path from the expander or the radiator to the expander so as to merge with the refrigerant in the expansion process or the refrigerant in the expansion process When,
A refrigeration cycle apparatus is provided.

  The compressor may be configured as a compression mechanism of an expander-integrated compressor (fluid machine) having a compression mechanism that compresses the refrigerant, an expansion mechanism that expands the refrigerant, and a shaft that connects the compression mechanism and the expansion mechanism. it can. Similarly, the expander can be configured as an expansion mechanism of an expander-integrated compressor.

  According to the refrigeration cycle apparatus, by providing the bypass circuit, a part of the low-density and high-enthalpy refrigerant after compression can be mixed with the high-density refrigerant before or in the expansion process. By appropriately adjusting the flow rate of the refrigerant to be bypassed according to the operating conditions, the radiator and the expansion unit can be expanded even under the condition that the rotation speeds of the compressor and the expander are equal and the volumes of the compressor and the expander are constant. It is possible to appropriately control the density of the refrigerant between the compressor and the expander. That is, since the volume flow rate of the refrigerant can be changed, the imbalance between the volume flow rates in the compressor and the expander can be eliminated or alleviated. Therefore, even if the operating conditions fluctuate due to seasonal fluctuations, load fluctuations, etc., the power recovery efficiency of the expander can be maintained high, and thus a refrigeration cycle apparatus having an excellent coefficient of performance can be provided. Furthermore, according to the present invention, the volume of the expander (expansion mechanism) can be designed to be large. In general, the expander has an increased efficiency because the leakage rate of the refrigerant decreases as the volume increases. Further, by increasing the volume of the expander, the volume ratio between the expander and the compressor can be reduced.

  Depending on the type of refrigerant and the operating conditions of the apparatus, there is generally a considerable gap between the density of refrigerant after compression and the density of refrigerant before expansion. Therefore, it is possible to greatly change the density of the refrigerant before expansion or in the expansion process by slightly bypassing the high-temperature and low-density refrigerant after compression. Since only a small amount of refrigerant is bypassed (for example, within 10% by mass of the total amount of refrigerant after compression), the reduction in the performance of the radiator has little effect on the coefficient of performance, and the improvement of the coefficient of performance is sufficiently achieved by recovering power. Can be expected.

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

(First embodiment)
FIG. 1 is a block diagram showing the configuration of the refrigeration cycle apparatus of the first embodiment. The refrigeration cycle apparatus 300A includes a main refrigerant circuit 301 through which refrigerant circulates. The main refrigerant circuit 301 includes a compression mechanism 120 that compresses the refrigerant, a radiator 310 that radiates the refrigerant compressed by the compression mechanism 120, an expansion mechanism 130 that expands the refrigerant radiated by the radiator 310, and a refrigerant expanded by the expansion mechanism 130. And a plurality of main pipes 330 that connect these elements in this order.

  The compression mechanism 120, the expansion mechanism 130, the shaft 127, and the electric motor 180 each constitute a part of the expander-integrated compressor 100A. In the expander-integrated compressor 100A, the compression mechanism 120 and the expansion mechanism 130 are connected to each other by a shaft 127 and always rotate synchronously. The compression mechanism 120 is activated by the electric motor 180 driving the shaft 127 to rotate. The expansion mechanism 130 converts the expansion force when the refrigerant expands into torque and applies it to the shaft 127 to assist the rotational drive of the shaft 127 by the electric motor 180. High power recovery efficiency can be expected by this mechanism in which the expansion energy of the refrigerant is directly transmitted to the compression mechanism 120 without being converted into electrical energy.

  The refrigeration cycle apparatus 300 </ b> A further includes a bypass circuit 302 branched from the main refrigerant circuit 301. The bypass circuit 302 includes a bypass pipe 360 and a flow rate adjustment valve 350. The start end of the bypass circuit 302 is connected to a portion (main pipe 330) between the compression mechanism 120 and the radiator 310 of the main refrigerant circuit 301, and the end is between the radiator 310 and the expansion mechanism 130 of the main refrigerant circuit 301. (Main piping 330). A part of the refrigerant compressed by the compression mechanism 120 and radiated by the radiator 310 is bypassed to the path from the radiator 310 to the expansion mechanism 130 without flowing into the radiator 310 and is radiated by the radiator 310. Merges with refrigerant before expansion.

  The flow rate adjustment valve 350 (flow rate adjuster) makes it possible to adjust the flow rate of the refrigerant flowing through the bypass circuit 302. By adjusting the flow rate of the refrigerant flowing through the bypass circuit 302, the volume flow rate of the refrigerant drawn into the expansion mechanism 130 can be freely adjusted. Instead of the flow rate adjustment valve 350, a pump capable of pumping the refrigerant may be employed.

  The refrigeration cycle apparatus 300 </ b> A further includes a first temperature sensor 311, a second temperature sensor 313, and a third temperature sensor 315. The first temperature sensor 311 is provided on the main refrigerant circuit 301 between the connection position (merging position) between the main refrigerant circuit 301 and the end of the bypass circuit 302 and the expansion mechanism 130. The temperature of the combined refrigerant that flows through the main refrigerant circuit 301 toward the expansion mechanism 130 from the connection position with the end of the bypass circuit 302 is measured. The second temperature sensor 313 is provided on the main refrigerant circuit 301 between the connection position (branch position) between the main refrigerant circuit 301 and the start end of the bypass circuit 302 and the compression mechanism 120, and is discharged from the compression mechanism 120. The temperature of the refrigerant before branching is measured. The third temperature sensor 315 is provided on the main refrigerant circuit 301 between the expansion mechanism 130 and the evaporator 320, and measures the temperature of the refrigerant before being expanded by the expansion mechanism 130 and flowing into the evaporator. Since the third temperature sensor 315 measures the temperature of the refrigerant in the gas-liquid two-phase region, the third temperature sensor 315 may be provided inside the evaporator 320. These temperature sensors 311, 313, and 315 are sensors using, for example, thermocouples or thermistors, and their output signals are sent to the controller of the refrigeration cycle apparatus 300 </ b> A via an amplification circuit and an A / D conversion circuit (not shown). 305 (see FIG. 6).

  As shown in FIG. 6, the controller 305 is based on the measurement results of the temperature sensors 311, 313, 315 and the actual measurement values such as the operating state (rotation speed, current value, power consumption) of the electric motor 180, etc. The opening degree of the flow rate adjustment valve 350 is controlled so that the coefficient of performance of 300A approaches the maximum value. Specifically, the state of the refrigerant sucked into the expansion mechanism 130 and the state of the refrigerant sucked into the compression mechanism 120 are estimated from the measured values. The state of the refrigerant to be estimated may be the refrigerant density ρe before being sucked into the expansion mechanism 130 and the refrigerant density ρc before being sucked into the compression mechanism 120. The densities ρe and ρc are the refrigerant density ρe at the inlet of the expansion mechanism 130 and the refrigerant density ρc at the inlet of the compression mechanism 120, respectively, and if these are known, the flow rate adjustment valve is set so that the coefficient of performance approaches the maximum value. The opening degree of 350 can be controlled.

  In order to derive the densities ρe and ρc, generally, the temperature and pressure of the refrigerant are required. In this embodiment, a method of deriving without using the pressure sensor is adopted. The density ρe and ρc of the refrigerant is estimated (derived) using, for example, measurement results of the temperature sensors 311, 313, and 315 and actual measurement values such as the operating state (rotation speed, current value, power consumption) of the electric motor 180. Can do. The operating state of the electric motor 180 can be known from an inverter or current sensor that drives the electric motor 180. The correspondence between the actually measured value obtained from the sensor or the like and the estimated values of the densities ρe and ρc is checked in advance by computer simulation or a testing machine, and a correlation equation or database for finding the correspondence is obtained by the controller 305 of the refrigeration cycle apparatus 300A. (Fig. 6). This makes it possible to estimate the densities ρe and ρc without using a pressure sensor.

  For example, the refrigerant density ρc at the inlet of the compression mechanism 120 can be estimated from the measurement result of the third temperature sensor 315 and the degree of superheat of the refrigeration cycle. The degree of superheat of the refrigeration cycle is a value that is set within a predetermined range (for example, 2 ° C. to 5 ° C.) according to operating conditions, and is adjusted by changing the heat exchange amount of the evaporator 320 by increasing or decreasing the fan air volume, for example. can do. The refrigerant density ρe at the inlet of the expansion mechanism 130 can be estimated from (1) a method of estimating from three measurement results of the temperature sensors 311, 313, and 315, or (2) a measurement result of the first temperature sensor 311 and consumption of the electric motor 180. There is a method of estimating from electric power. However, there are various methods for estimating the densities ρe and ρc, and the present invention is not limited to these.

  In addition, the controller 305 gives a command to the inverter 317 so that the electric motor 180 is driven at a rotation speed at which the required heating capacity or cooling capacity is exhibited. Inverter 317 controls electric motor 180 based on a command from controller 305. The inverter 317 can be configured as an inverter unit including a control system such as a microcomputer. Therefore, the role of the controller 305 may be shared by the microcomputer of the inverter 317.

As shown in FIG. 9A, when the refrigeration cycle apparatus 300 </ b> A of the present embodiment is applied to the water heater 500, the radiator 310 plays a role of a heater that warms water. The controller 305 derives from the output signals of the water temperature sensor 502 and the hot water temperature sensor 503 provided in the water heater 500 and the pump 501 provided in the water heater 500 in order to derive the heating capacity Q _GC of the radiator 310. The rotation speed signal is acquired. A water temperature sensor 502, a radiator 310 provided in a path 504 to send water (pipe 504), for measuring the temperature T _in the water flowing into the radiator 310. The hot water temperature sensor 503 is provided in a path 505 (pipe 505) for sending hot water from the radiator 310 to a use point such as the hot water storage tank 506, and measures the temperature T _out of hot water flowing out from the radiator 310. Water V _in passing through the radiator 310 from the rotational speed of the pump 501 is obtained. The heating capacity Q _GC (kW) of the radiator 310 is obtained from the difference ΔT (= T _out −T _in ) between the hot water temperature T _out and the water temperature T _in and the amount of water V _in .

  2 is a longitudinal sectional view of the expander-integrated compressor 100A shown in FIG. 1, FIG. 3A is a sectional view taken along the line A1-A1 shown in FIG. 2, and FIG. 3B is a sectional view taken along the line B1-B1. As shown in FIG. 2, the expander-integrated compressor 100 </ b> A includes a sealed container 101, a compression mechanism 120 disposed in the sealed container 101, an expansion mechanism 130 disposed in the same sealed container 101, a compression mechanism 120, and an expansion mechanism. A shaft 127 that couples the mechanism 130 and an electric motor 180 that rotationally drives the shaft 127 are provided.

  A suction pipe 112 that sucks in the refrigerant and a discharge pipe 113 that discharges the compressed refrigerant are connected to the compression mechanism 120 so as to penetrate the inside and outside of the sealed container 101. Similarly, a suction pipe 114 that sucks refrigerant and a discharge pipe 115 that discharges the refrigerant after expansion are connected to the expansion mechanism 130 so as to penetrate the inside and outside of the sealed container 101. The suction pipes 112 and 114 and the discharge pipes 113 and 115 are parts corresponding to the main pipe 330 constituting the main refrigerant circuit 301 shown in FIG. A bypass pipe 360 constituting a bypass circuit 302 is connected to the suction pipe 114 of the expansion mechanism 130, and the refrigerant bypasses the inlet of the expansion mechanism 130. If the bypass pipe 360 is connected to the suction pipe 114 in this way, there is a structural advantage that the processing of the cylinder of the expansion mechanism 130 is unnecessary and the connection outside the sealed container 101 is possible. However, it is also possible to directly connect the bypass circuit 302 to the expansion mechanism 130 as in a refrigeration cycle apparatus 300E (see FIG. 14) of a fifth embodiment described later.

  In FIG. 1, the first temperature sensor 311 is disposed closer to the expansion mechanism 130 than the connection position between the main pipe 330 (suction pipe 114) that connects the radiator 310 and the expansion mechanism 130 and the bypass pipe 360. However, it is omitted in FIG.

  The electric motor 180 includes a rotor 181 fixed to the shaft 127 and a stator 182 fixed to the sealed container 101. A terminal 184 is provided on the upper portion of the sealed container 101, and electric power is supplied to the electric motor 180 through a wiring 183 having one end connected to the terminal 184 and the other end connected to the stator 182.

  The compression mechanism 120 is of a scroll type and includes a turning scroll 124, a fixed scroll 122, an Oldham ring 128, a bearing member 121, a suction pipe 112, and a discharge pipe 113. The orbiting scroll 124 fitted to the eccentric shaft 127a of the shaft 127 and constrained to rotate by the Oldham ring 128 rotates the shaft 127 while the spiral wrap 124a meshes with the wrap 122a of the fixed scroll 122. Accordingly, a swirl motion is performed, and the crescent-shaped working chamber 124h formed between the wraps 124a and 122a reduces the volume while moving from the outside to the inside, thereby compressing the refrigerant sucked from the suction pipe 112. The compressed refrigerant is discharged from the discharge pipe 113 via a discharge port 126 formed at the center of the fixed scroll 122.

  The bypass pipe 360 may be directly connected to the compression mechanism 120, that is, the bypass circuit 302 may be directly branched from the discharge port 126.

  As shown in FIGS. 2, 3A, and 3B, the expansion mechanism 130 is a two-stage rotary type, and includes an upper bearing member 131, a first cylinder 132, an intermediate plate 133, a second cylinder 134, a lower bearing member 135, a first bearing member. A roller 136 (first piston), a second roller 137 (second piston), a first vane 138, a second vane 141, a first spring 139, and a second spring 142 are provided.

  As shown in FIG. 2, the first cylinder 132 is fixed to the lower portion of the upper bearing member 131 that supports the shaft 127. An intermediate plate 133 is fixed to the lower portion of the first cylinder 132, and a second cylinder 134 is fixed to the lower portion of the intermediate plate 133. The first roller 136 is disposed in the first cylinder 132 and is rotatably fitted to the first eccentric portion 127b of the shaft 127. The second roller 137 is disposed in the second cylinder 134 and is rotatably fitted to the second eccentric portion 127c of the shaft 127. As shown in FIG. 3A, the first vane 138 is slidably disposed in a vane groove formed in the first cylinder 132. As shown in FIG. 3B, the second vane 141 is slidably disposed in the vane groove of the second cylinder 134. The first vane 138 is pressed against the first roller 136 by the first spring 139, and the space between the first cylinder 132 and the first roller 136 forms a suction side space 140 (working chamber A) and a discharge side space 144 a (working). Partition into room B). The second vane 141 is pressed against the second roller 137 by the second spring 142, and the space between the second cylinder 134 and the second roller 137 forms a suction side space 144 b (working chamber C) and a discharge side space 143 (working). Partition into room D). The middle plate 133 communicates with the discharge side space 144a of the first cylinder 132 and the suction side space 144b of the second cylinder 134, so that one expansion chamber (working chamber B + working chamber C) is formed by both spaces 144a and 144b. A communication hole 145 is formed.

  In the present embodiment, the first vane 138 and the second vane 141 have the same angular position around the shaft 127. Further, the eccentric directions of the first eccentric portion 127b and the second eccentric portion 127c also coincide. However, the angular position and / or the eccentric direction may be arranged so as to deviate by a certain angle.

  As shown in FIGS. 3A and 3B, the refrigerant sucked into the expansion mechanism 130 from the suction pipe 114 is guided to the suction side space 140 through the suction port 116 formed in the first cylinder 132. As the shaft 127 rotates, the suction side space 140 of the first cylinder 132 is disconnected from the suction port 116 and changes to the discharge side space 144a. When the shaft 127 further rotates, the refrigerant that has moved to the discharge side space 144a of the first cylinder 132 is guided to the suction side space 144b of the second cylinder 134 via the communication hole 145 of the intermediate plate 133. When the shaft 127 further rotates, the volume of the suction side space 144b of the second cylinder 134 increases and the volume of the discharge side space 144a of the first cylinder 132 decreases, but the volume of the suction side space 144b of the second cylinder 134 increases. Since the amount is larger than the volume reduction amount of the discharge side space 144a of the first cylinder 132, the refrigerant expands. At this time, since the expansion force of the refrigerant is applied to the shaft 127, the load on the electric motor 180 is reduced. When the shaft 127 further rotates, the communication between the discharge side space 144a of the first cylinder 132 and the suction side space 144b of the second cylinder 134 is cut off, and the suction side space 144b of the second cylinder 134 enters the discharge side space 143. Change. The refrigerant that has moved to the discharge side space 143 of the second cylinder 134 is discharged from the discharge pipe 115 via the discharge port 146 formed in the second cylinder 134.

  The suction pipe 114 is connected to a suction port 116 that is a refrigerant suction portion of the expansion mechanism 130. A bypass pipe 360 is connected to the suction pipe 114 drawn out of the sealed container 101. The suction pipe 114 and the bypass pipe 360 can be connected using a joint such as a T-shaped pipe. Note that the suction pipe 114 and the bypass pipe 360 may be connected in the sealed container 101.

  Note that the types of the compression mechanism and the expansion mechanism are not limited to the present embodiment, and a positive displacement mechanism such as a scroll type or a rotary type can be appropriately employed.

Next, the effect obtained by the bypass circuit 302 will be described in detail.
The type of the refrigerant is carbon dioxide that becomes supercritical at a high pressure in the refrigeration cycle, and the case where the refrigeration cycle apparatus 300A in FIG. 1 is applied to the water heater 500 (see FIG. 9A) will be described as an example. Note that the refrigerant is not limited to carbon dioxide, and a chlorofluorocarbon refrigerant in which the high pressure of the refrigeration cycle is not supercritical can be used.

First, consider a case where no refrigerant flows through the bypass circuit 302.
In the expander-integrated compressor 100A of the present embodiment, the volume Vc of the compression mechanism 120 and the volume Ve of the expansion mechanism 130 both have certain design values. The volume ratio (Vc / Ve) between the compression mechanism 120 and the expansion mechanism 130 is constant, and the ratio (ρe) of the refrigerant density ρe at point N _{1 and} the refrigerant density ρc at point L in the Mollier diagram of FIG. 4A. Ideally equal to / ρc). The density ρe is the density of the refrigerant before expansion at the inlet of the expansion mechanism 130, and the density ρc is the density of the refrigerant at the inlet of the compression mechanism 120.

Density ρe of the refrigerant at the inlet of the expansion mechanism 130, depending on the operating conditions, for example, varies in the range of ^{600kg / m 3 ~1000kg / m 3} . Density ρc of the refrigerant at the inlet of the compression mechanism 120, for example, varies in the range of ^{90kg / m 3 ~110kg / m 3} . When converted to a density ratio (ρe / ρc), it is about 7-11. For example, since the temperature of water to be warmed by the radiator 310 is high in summer, the temperature of the refrigerant discharged from the radiator 310 is also high. That is, the density ρe is reduced, and the density ratio (ρe / ρc) is about 7. Therefore, if the design is made such that the volume ratio (Vc / Ve) of the compression mechanism 120 and the expansion mechanism 130 is about 7, the ideal represented by LMN ₁ O ₁ in summer conditions without special measures. Operation with a typical refrigeration cycle and high power recovery efficiency.

On the other hand, since the water temperature decreases in the winter season, the temperature of the refrigerant discharged from the radiator 310 also decreases, and the point N _{1 of the} refrigeration cycle shifts to a point N ₂ on the low temperature side. That is, the density ρe of the refrigerant is larger than that in the summer, and the density ratio (ρe / ρc) is increased to about 11 at the maximum. However, since the volume ratio (Vc / Ve) cannot be changed while the density ratio (ρe / ρc) changes, the volume flow rates in the compression mechanism 120 and the expansion mechanism 130 are unbalanced. On the other hand, as long as the presence of the bypass circuit 302 is ignored, the mass flow rate of the refrigerant is constant no matter where the refrigerant circuit is measured. Eventually, the action of forcibly balancing the volume flow rate works, and the refrigerant having a volume corresponding to the volume Ve does not enter the expansion mechanism 130.

When the volume of the refrigerant entering the expansion mechanism 130 decreases, the original expansion process N ₁ O ₁ of the refrigeration cycle shifts to an expansion process N ₂ O ₂ as shown in FIG. 4A. The expansion process N ₂ O ₂ is isentropic expansion in which the pressures P _{1 to} P ₂ contribute to power recovery, and the pressures P _{2 to} P ₃ are isentropic expansion that does not contribute to power recovery. Since the volume entering the expansion mechanism 130 is insufficient, the refrigerant cannot be isentropically expanded from high pressure to low pressure, resulting in insufficient expansion. As a result, the power recovery amount in winter (h ₂ -h ₄ ) is smaller than the power recovery amount in summer (h ₁ -h ₃ ). This is shown in FIG. 5A in a PV diagram of the expansion process. The pressures P _{2 to} P ₃ are constant volume changes with a constant enthalpy. The difference in power recovery between summer and winter corresponds to the area S ₁ .

On the other hand, consider the case where the bypass circuit 302 is used.
When the high-temperature and low-density refrigerant between the compression mechanism 120 and the radiator 310 is mixed with the low-temperature and high-density refrigerant before expansion, the refrigerant density ρe at the inlet of the expansion mechanism 130 becomes low. Then, the imbalance in volume flow rate is alleviated, and a volume of refrigerant corresponding to the volume Ve enters the expansion mechanism 130. As shown in the Mollier diagram of FIG. 4B, the expansion process N ₂ O ₂ of the refrigeration cycle before using the bypass circuit 302 is shifted to the expansion process N ₃ O ₃ on the high enthalpy side, and the expansion shortage is alleviated. The power recovery amount (h ₅ -h ₆ ) at this time is close to the summer power recovery amount (h ₁ -h ₃ ), and the winter power recovery amount (h ₂ -h ₄ ) when the bypass circuit 302 is ignored. Bigger than. As shown in the PV diagram of FIG. 5B, the area S ₂ (<S ₁ ) is the difference in the amount of recovered power in summer and winter.

Note that by bypassing a part of the low-density refrigerant, the mass flow rate of the refrigerant passing through the radiator 310 is reduced, and the ability of the radiator 310 is slightly reduced. However, the difference between the power recovery amount (h ₂ −h ₄ ) when the refrigerant is not bypassed and the power recovery amount (h ₅ −h ₆ ) when the refrigerant is bypassed is the reduction in the capacity of the radiator 310. There is no problem if the control is performed to exceed the above. In short, when the density ρe of the refrigerant is too low, the bypass circuit 302 is used to increase the density ρe and increase the coefficient of performance.

  In FIG. 7, the control flowchart of refrigeration cycle apparatus 300A by the controller 305 is shown. The controller 305 regularly maintains the coefficient of performance (COP) of the refrigeration cycle apparatus 300A near the optimum value by periodically executing the control shown in this flowchart.

  In step ST1, the controller 305 acquires signals from the temperature sensors 311, 313, and 315. Next, in step ST <b> 2, data specifying the current value and rotation speed of the electric motor 180 is acquired from the inverter 317.

Next, in step ST3, the heating capability Q _GC of the radiator 310 is derived. The heating capacity Q _GC of the radiator 310 is obtained from the difference ΔT between the water temperature T _{in at} the inlet and the hot water temperature T _{out at the} outlet of the radiator 310 and the amount of water V _in that has passed through the radiator 310 as described with reference to FIG. 9A. be able to.

Another method for deriving the heating capability Q _GC of the radiator 310 is as follows. Estimating the enthalpy h _{GC_in} of refrigerant flowing into the radiator 310 and the enthalpy h _{GC_out} refrigerant discharged from the radiator 310. By multiplying the estimated enthalpy difference Δh = (h _{GC_in} −h _{GC_out} ) by a variable Q _C determined corresponding to the rotation speed of the electric motor 180, the heating capacity Q _GC can be obtained (Q _GC = Q _C · Δh).

  Specifically, as shown in FIG. 9B, temperature sensors 325 and 327 and pressure sensors 326 and 328 are provided at the inlet and the outlet of the radiator 310, respectively, and outputs of the temperature sensors 325 and 327 and the pressure sensors 326 and 328 are provided. A signal is provided to the controller 305. The sensors 325 and 326 on the inlet side of the radiator 310 are preferably provided on the main refrigerant circuit 301 between the radiator 310 and the compression mechanism 120. Sensors 327 and 328 on the outlet side of the radiator 310 are on the main refrigerant circuit 301 between the radiator 310 and the expansion mechanism 130, and more than the junction point of the main refrigerant circuit 301 and the bypass circuit 302. It should be provided on the side.

When cooling the air or water with the evaporator 320, the cooling capacity Q _EVA of the evaporator 320 is derived instead of the heating capacity Q _GC of the radiator 310. For example, in the air conditioner, the cooling capacity Q _EVA of the evaporator 320 can be directly known, such as the fan rotation speed, the degree of superheat, the refrigerant temperature in the main refrigerant circuit 301, the current value and the rotation speed of the electric motor 180. It can be determined using one or more of the conditions. More precisely, (1) the enthalpy of the refrigerant at the inlet of the evaporator 320 is derived from the fan rotation speed of the radiator 310 and the temperature of the refrigerant at each of the inlet and outlet of the radiator 310, and (2) compression The degree of superheat is derived from the discharge temperature of the mechanism 120, and (3) the characteristic circulation amount (refrigerant circulation amount per unit time) is derived from the rotation speed of the electric motor 180. And the capability Q _EVA of the evaporator 320 can be derived _| led-out using the result of these (1)-(3).

Returning to FIG. 7, the description will be continued. In step ST3, the after deriving a current heating capacity Q _GC, the derived heating capacity Q _GC to determine if a whether the required capacity Q _req above. The required capacity Q _req is a value determined according to the temperature and water temperature of hot water to be stored in the hot water storage tank in the case of a water heater, and the air conditioning temperature and air volume in the case of an air conditioner. If the heating capacity Q _GC is greater than or equal to the required capacity Q _req , the process proceeds to step ST5, where the absolute value of the difference between Q _GC and Q _req is compared with a predetermined threshold value φQ. If the absolute value of the difference between Q _GC and Q _req is not less than threshold value φQ, that is, greater than or equal to threshold value φQ, a command is given to inverter 317 (see FIG. 6) in step ST6, and the electric motor Control to reduce the rotational speed of 180 is performed.

If the heating capacity Q _GC is less than the required capacity Q _{req in} ST4, the process proceeds to step ST7, and the magnitude comparison between the absolute value of the difference between Q _GC and Q _req and a predetermined threshold φQ is performed. Do. If the absolute value of the difference between Q _GC and Q _req is greater than or equal to the threshold value φQ, in step ST8, a command is given to the inverter 317 (see FIG. 6) to perform control to increase the rotation speed of the electric motor 180. . Thus, in this embodiment, as long as the Q _GC is within a certain range around the Q _req, the rotational speed of the electric motor 180 is adapted to not change, that is, provided a dead zone.

On condition that Q _GC is within around a Q _req within a certain range (e.g., Q _req ± 5%), the process proceeds to step ST9, the current density ratio of the refrigeration cycle (ρe / ρc), optimal density ratio (Ρe / ρc) Comparison with _OP is performed. As described above, the refrigerant density ρe at the inlet of the expansion mechanism 130 and the refrigerant density ρc at the inlet of the compression mechanism 120 are the measurement results of the temperature sensors 311, 313, 315, the power consumption and rotation of the motor 180. Estimate using numbers.

The optimum density ratio (ρe / ρc) _OP will be described. FIG. 10 is a correlation diagram showing the relationship among refrigerant density ρe, expander efficiency η _e , bypass opening ξ _b, and coefficient of performance (COP). The refrigerant density ρe is on the horizontal axis, and the other is on the left and right vertical axes. The expander efficiency η _e means (actual recovery power / theoretical recovery power).

Expander efficiency eta _e is high and low pressure P _H of the refrigeration cycle, determined by the refrigerant temperature T _e sucked and P _L, is known to decrease as the density of the refrigerant ρe increases. On the other hand, the density ρe of the refrigerant is larger as the bypass opening xi] _b increases, when the bypass opening xi] _b is too large, the amount of the refrigerant flowing through the condenser 310 is reduced, lowering the coefficient of performance in the opposite To do. Therefore, the coefficient of performance curve has a local maximum corresponding to the expansion mechanism rate η _e and the bypass opening ξ _b , and the optimal density ratio (ρe / ρc) _OP is determined in advance corresponding to the local maximum of the coefficient of performance. it can.

The coefficient of performance curve as shown in FIG. 10 also depends on conditions such as the number of revolutions of the electric motor 180, the degree of superheat, the temperature of water to be heated by the radiator 310, and the outside air temperature. For example, a database in which the above conditions are associated with the optimum density ratio can be created in advance, and this database can be input to the controller 305. In this way, it is possible to select and set the optimum density ratio (ρe / ρc) _OP according to the season and driving situation at any time by referring to the database using the above conditions as search keys.

  Since the refrigerant density ρc at the inlet of the compression mechanism 120 does not change so much, it is input as a constant value to the controller 305 in advance, and only the refrigerant density ρe at the inlet of the expansion mechanism 130 is changed to a temperature or the like. The current density ratio (ρe / ρc) may be derived by estimation from actual measurement values.

If it is determined in step ST9 that the current density ratio (ρe / ρc) is equal to or greater than the optimum density ratio (ρe / ρc) _OP , the process proceeds to step ST10, where the current density ratio (ρe / ρc) and the optimum density are determined. The absolute value of the difference from the ratio (ρe / ρc) _OP is compared with a predetermined threshold value φ (ρe / ρc). When the absolute value is not less than the threshold value φ (ρe / ρc), that is, not less than the threshold value φ (ρe / ρc), in step ST11, the bypass opening (the opening of the flow rate adjusting valve 350). Control to enlarge.

On the other hand, if the current density ratio (ρe / ρc) is less than the optimum density ratio (ρe / ρc) _OP , the process proceeds to step ST12, and the absolute value of the difference between the two and the threshold value φ (ρe / ρc) Compare size with. If the absolute value is greater than or equal to the threshold value φ (ρe / ρc), in step ST13, control is performed to reduce the bypass opening (the opening of the flow rate adjustment valve 350). As long as the current density ratio (ρe / ρc) is within a certain range centered on the optimum density ratio (ρe / ρc) _OP , the opening degree of the flow regulating valve 350 is not changed, that is, the dead zone. Is provided.

With the above procedure, the flow rate adjustment valve 350 can be controlled so that the coefficient of performance approaches the maximum value while exhibiting the required capacity Q _req .

  Further, the control may be performed according to the flowchart shown in FIG. 8 instead of the flowchart shown in FIG.

In step S < _b > 1, the controller 305 reads the current bypass opening ξ _b from the memory and acquires signals from the temperature sensors 311, 313, and 315. In step S <b> 2, data specifying the current value and the rotation speed of the electric motor 180 is acquired from the inverter 317. In step S3, the current heating capacity Q _GC or cooling capacity Q _EVA and the power consumption of the motor 180 are derived. The processing of steps S1 to S3 corresponds to the processing of steps ST1 to ST3 in the flowchart of FIG.

Next, in step S4, when the heating capacity Q _GC or cooling capacity Q _EVA it is determined whether a required capacity Q _req to less than the required capacity Q _req, the process proceeds to step S5, rotation of the electric motor 180 Increase the number. The processes in steps S4 and S5 may be replaced with the processes in steps ST4 to ST8 in the flowchart of FIG.

Next, in step S <b> 6, current densities ρe and ρc are derived (estimated) from the measurement results of the temperature sensors 311, 313 and 315 and the power consumption of the electric motor 180. Next, in step S7, a bypass control target opening ξ _obj and a control threshold value Δξ are derived. The bypass control target opening ξ _obj that maximizes the coefficient of performance can be input in advance to the controller 305 in the form of a correlation equation or database corresponding to the refrigerant density ρe, ρc. Therefore, step 7 is a process of finding an appropriate bypass control target opening ξ _obj from the database using the density ρe, ρc obtained in step S6 as a search key, or using the obtained density ρe, ρc as a parameter. It may be a process of finding a bypass control target opening ξ _obj from a predetermined correlation equation. For example, ± 5% of the bypass control target opening ξ _obj is assigned to the control threshold value Δξ.

Next, in step S8, the bypass control target opening degree ξ _obj is compared with the current bypass opening degree ξ _b . If the current bypass opening ξ _b is greater than or equal to the bypass control target opening ξ _obj , the process proceeds to step S9, where it is determined whether or not the difference between the two is less than the control threshold value Δξ. If it is determined, the bypass opening (the opening of the flow rate adjustment valve 350) is reduced in step S10. On the other hand, if the current bypass opening ξ _b is equal to or greater than the bypass control target opening ξ _obj , the process proceeds to step S9 to determine whether the difference between the two is less than the threshold value Δξ. If it is determined that there is, the bypass opening (the opening of the flow rate adjusting valve 350) is increased in step S12.

(Second Embodiment)
The refrigeration cycle apparatus 300A according to the first embodiment is configured to measure the temperature of the refrigerant and derive the density ρe on the expansion mechanism 130 side from the connection position of the main refrigerant circuit 301 and the bypass circuit 302. However, an embodiment in which the bypass pipe 360 is directly connected to the suction port 116 (see FIG. 2) of the expansion mechanism 130 is also conceivable, and the length of the pipe necessary for arranging the sensors may not be sufficient. Conceivable. In such a case, the density ρe of the refrigerant sucked into the expansion mechanism 130 can be indirectly derived (estimated) from the following (1) to (3).

(1) Rotation speed of compression mechanism 120 (rotation speed of electric motor 180)
(2) Density of refrigerant discharged from the radiator 310 before joining the refrigerant that has flowed through the bypass circuit 302 (3) Flow rate of refrigerant that flows through the bypass circuit 302 (opening degree of the flow rate adjustment valve 350)

  Specifically, as in the refrigeration cycle apparatus 300B of the present embodiment shown in FIG. 11, the temperature on the main refrigerant circuit 301 between the radiator 310 and the connection position of the main refrigerant circuit 301 and the end of the bypass circuit 302 is increased. A sensor 311 can be provided. The temperature of the refrigerant discharged from the radiator 310 before joining the refrigerant that has flowed through the bypass circuit 302 is measured by the temperature sensor 311. The flow rate of the refrigerant flowing through the bypass circuit 302 can be specified from the opening degree of the flow rate adjustment valve 350. Data specifying the opening degree of the flow rate adjustment valve 350 can be held in the memory of the controller 305 at all times. Moreover, the data for specifying the rotation speed of the electric motor 180 may be acquired from the inverter 317 as necessary, or the controller 305 itself may always hold the data.

(Third embodiment)
In the refrigeration cycle apparatus 300A of the first embodiment, the application target is a water heater, but the present invention is not limited to this. For example, the refrigeration cycle apparatus 300C shown in FIG. 12 assumes an air conditioner as an application target. In the configuration of the refrigeration cycle apparatus 300C of the present embodiment, the functions of the radiator 310 and the evaporator 320 are switched to each other by the four-way valves 380 and 380. Others are basically the same as the refrigeration cycle apparatus 300A of the first embodiment.

  Each of the radiator 310 and the evaporator 320 is a fin-and-tube heat exchanger. Of the two heat exchangers functioning as the radiator 310 or the evaporator 320, one is incorporated in the indoor unit and the other is incorporated in the outdoor unit. When the room is cooled, the heat exchanger of the indoor unit functions as the evaporator 320, and the heat exchanger of the outdoor unit functions as the radiator 310. When the room is heated, the heat exchanger of the indoor unit functions as the radiator 310, and the heat exchanger of the outdoor unit functions as the evaporator 320.

  Of course, you may apply the mechanism which switches the distribution direction of a refrigerant | coolant with a four-way valve to the refrigerating-cycle apparatus of other embodiment. In that case, the radiator and the evaporator are not only fin-and-tube heat exchangers that exchange heat between the refrigerant and gaseous air, but also water such as double-tube heat exchangers that exchange heat between the refrigerant and water. It may be a heat exchanger.

(Fourth embodiment)
The refrigeration cycle apparatus 300A of the first embodiment performs all controls without using a pressure sensor. However, as shown in the refrigeration cycle apparatus 300D of the present embodiment, the pressure sensors 312 and 314 are used. May be. The first pressure sensor 312 measures the refrigerant pressure at the inlet of the expansion mechanism 130, and the second pressure sensor 314 measures the refrigerant pressure at the inlet of the compression mechanism 120. By using these pressure sensors 312 and 314 and the temperature sensors 311 and 313, the densities ρe and ρc can be directly derived. Such pressure sensors 312 and 314 are sensors using, for example, piezoelectric elements, and output signals thereof are given to the controller 305 in the same manner as the temperature sensors 311, 313 and 315.

  The refrigeration cycle apparatus 300D shown in FIG. 13 further includes an oil separator 390 and a gas separator 370. The oil separator 390 separates the refrigeration oil from the refrigerant flowing through the bypass circuit 302 and returns the separated refrigeration oil between the evaporator 320 and the compressor 120 in the main refrigerant circuit 301. Thereby, it can prevent that refrigeration oil flows into the bypass circuit 302.

(Fifth embodiment)
In the refrigeration cycle apparatuses 300A, 300B, 300C, and 300D of the previous embodiment, the bypass pipe 360 is connected to the main pipe 330 (suction pipe 114) connected to the expansion mechanism 130. However, this configuration is not essential. That is, the bypass pipe 360 may be directly connected to the expansion mechanism 130 as in the refrigeration cycle apparatus 300E shown in FIG. In this case, where the bypass pipe 360 is connected to the expansion mechanism 130 becomes a problem. One possible suitable configuration is a configuration in which a bypass pipe 360 is connected to the suction port 116 (see FIG. 2) of the first cylinder 132. If it does in this way, the same effect as a 1st embodiment can be acquired.

  Another preferred configuration is a configuration in which a bypass pipe 360 is connected to the second cylinder 134 of the expander-integrated compressor 100B, as shown in FIG. The expander-integrated compressor 100B illustrated in FIG. 15 is common to the expander-integrated compressor 100A illustrated in FIG. 2 except that the bypass pipe 360 is directly connected to the second cylinder 134. As described in the first embodiment, the rotary type expansion mechanism 130 has a mechanism in which one expansion chamber is formed by the first cylinder 132 and the second cylinder 134 and the refrigerant is confined in the expansion chamber for expansion. ing. Therefore, if the bypass circuit 302 is connected to the expansion chamber and a low-density refrigerant is sent directly to the expansion chamber, the density ρe of the refrigerant in the expansion process can be changed. Specifically, the connection destination of the bypass circuit 320 (bypass piping) is determined so that the refrigerant flowing through the bypass circuit 302 is directly injected into the expansion chamber. In the present embodiment, the bypass circuit 302 (bypass pipe 360) is connected to the second cylinder 134.

  16A and 16B are operation explanatory diagrams of the expansion mechanism 130 of the expander-integrated compressor 100B of FIG. The state of each cylinder 132, 134 is shown in time series at intervals of 90 ° of the rotation angle of the shaft 127, assuming that the refrigerant suction start time to the first cylinder 132 is 0 °. The configuration of the expansion mechanism 130 is the same as that of the other embodiments except that the bypass pipe 360 is connected to the second cylinder 134. The suction pipe 114 connected to the first cylinder 132 has an angle of about 45 ° with the vane. The mixing nozzle 147 as the bypass pipe 360 is connected to the second cylinder 134 at a position where the angle formed with the vane is about 67.5 °. The mixing nozzle 147 has a function of injecting a low density and high enthalpy refrigerant into the second cylinder 134 via an injection port 148 formed in the second cylinder 134.

  As shown in FIG. 16A, when the rotation angle is 0 °, the refrigerant 201 is prepared in the suction pipe 114, and the volume of the suction side space 140 of the first cylinder 132 is zero. As the shaft 127 rotates counterclockwise, the suction of the refrigerant 201 into the suction side space 140 of the first cylinder 132 is started. At least until the rotation angle is 270 °, the communication hole 145 of the intermediate plate 133 and the suction side space 140 do not communicate with each other, so the refrigerant 201 does not move to the second cylinder 134. When the rotation angle of the shaft 127 is between 270 ° and 360 °, the communication hole 145 begins to open, and the refrigerant 201 starts to flow into the suction side space 144b of the second cylinder 134.

  As shown in FIG. 16B, when the rotation angle reaches 360 °, the first cylinder 132 finishes sucking the refrigerant 201. From that point, the refrigerant 201 filled in the discharge side space 144a of the first cylinder 132 and the suction side space 144b of the second cylinder 134 starts to expand. On the other hand, the first cylinder 132 starts to suck new refrigerant 202. When the shaft 127 further rotates and the rotation angle exceeds 382.5 °, the refrigerant flowing through the bypass circuit 302 flows into the suction side space 144b via the mixing nozzle 147 and the injection port 148 of the second cylinder 134. start. When a low density refrigerant flows into the suction side space 144b, the low density refrigerant is supercritical liquid phase in the expansion chamber composed of the discharge side space 144a of the first cylinder 132 and the suction side space 144b of the second cylinder 134. It collides with the refrigerant 201 that has started to expand from the target state to the gas-liquid two-phase state. Thereby, the change to a gas-liquid two phase is accelerated | stimulated. In the second cylinder 134, when the rotation angle is between 630 ° and 720 °, communication between the discharge side space 143a and the discharge port 146 starts, and discharge of the refrigerant 201 after expansion starts.

  Since the expansion mechanism 130 operates at a speed of several tens of revolutions per second, the expansion process of the refrigerant ends in an instant. However, as shown in FIG. 17, the change from the single phase to the gas-liquid two phase may not catch up with the operation of the expansion mechanism 130 and may cause a pressure drop due to the phase change delay. The pressure drop due to the phase change delay is accompanied by a power recovery loss corresponding to the shaded area.

  However, according to this embodiment, a low-density refrigerant is mixed with the refrigerant in the expansion process. That is, the gas / liquid interface is positively formed by mixing the gas refrigerant with the refrigerant in the supercritical (or liquid phase) liquid phase state. Such an interface promotes the change of the refrigerant from the liquid phase to the gas-liquid two phase. Accordingly, the occurrence of a phase change delay as shown in FIG. 15 is prevented, a power recovery loss due to the phase change delay does not occur, and a better coefficient of performance is achieved. In particular, it is preferable to carry out the above mixing from the start of the expansion process to the start of the change to the gas-liquid two phase. The expansion process starts when the discharge side space 144a of the first cylinder 132 and the suction side space 144b of the second cylinder 134 are connected together via the communication hole 145, so that the mixing nozzle 147 has the communication hole 145. It is preferable to connect to the second cylinder 134 within an angle range of 90 ° in the rotation direction of the shaft 127 from the formed position. In some cases, an injection port may be formed in the intermediate plate 133 so that the gas refrigerant can be injected into the communication hole 145, and the mixing nozzle 147 may be connected to the intermediate plate 133.

(Sixth embodiment)
The refrigeration cycle apparatuses 300A to 300E all use the expander-integrated compressors 100A and 100B. However, as shown in FIG. 18, a refrigeration cycle apparatus 300F in which the compressor 220 and the expander 230 are separated is also a preferred embodiment of the present invention. In brief, the refrigeration cycle apparatus 300F has a configuration in which a bypass circuit 302 is provided after an expansion valve of a conventional refrigeration cycle apparatus is replaced with an expander 230.

  The refrigeration cycle apparatus 300F can control the high pressure of the refrigeration cycle and optimize the refrigeration cycle efficiency by independently controlling the rotation speed of the compressor 220 and the rotation speed of the expander 230. It has been known. However, the efficiency of the electric motor that drives the compressor 220 and the generator that is driven by the expander 230 varies greatly depending on the rotational speed. The range of rotational speeds that can be operated with high efficiency is not so wide. Therefore, even if it is attempted to optimize the refrigeration cycle efficiency only by controlling the rotation speed of the compressor 220 or the expander 230, the efficiency reduction of the motor or the generator becomes a bottleneck, and it becomes difficult to satisfactorily increase the coefficient of performance. It is predicted. Further, the efficiency of the compressor 220 and the expander 230 itself also changes depending on the rotational speed.

  Therefore, the present invention is applied to the separation type refrigeration cycle apparatus 300F, and instead of changing the rotation speed of the compressor 220 or the expander 230, the density ρe of the refrigerant is changed by using the bypass circuit 302, and the refrigeration cycle is changed. A control method for optimizing efficiency can be proposed. According to this method, the efficiency of the refrigeration cycle can be optimized while keeping the efficiency of the electric motor driving the compressor 220 and the generator driven by the expander 230 high. Of course, both the rotation speed of the electric motor that drives the compressor 220 and the generator driven by the expander 230 and the refrigerant flow rate of the bypass circuit 302 may be controlled to optimize the refrigeration cycle efficiency. . In the example of FIG. 18, the first temperature sensor 311 is disposed closer to the radiator 310 than the confluence of the bypass circuit 302 and the main refrigerant circuit 301. The first temperature sensor 311 You may arrange | position to the expander 230 side rather than a point.

  The refrigeration cycle apparatus according to the present invention is excellent in power recovery efficiency, and is useful for an air conditioner, a water heater, various dryers, a refrigerator refrigerator, and the like.

The block diagram which shows the structure of the refrigerating-cycle apparatus of 1st Embodiment. Detailed longitudinal sectional view of the expander-integrated compressor shown in the block diagram of FIG. A1-A1 cross-sectional view of the expander-integrated compressor shown in FIG. B1-B1 cross-sectional view of the expander-integrated compressor shown in FIG. Mollier diagram explaining problems associated with changes in refrigerant density Mollier diagram explaining the effect of the present invention PV diagram explaining problems associated with refrigerant density change PV diagram explaining the effect of the present invention Block diagram of the control system of the refrigeration cycle apparatus shown in FIG. Control flowchart of the refrigeration cycle apparatus shown in FIG. Another preferred control flowchart of the refrigeration cycle apparatus shown in FIG. Arrangement of sensor groups used to derive the heating capacity of the radiator Arrangement of another example of sensor group used for deriving heating capacity of radiator Correlation diagram showing relationship between refrigerant density ρe, expander efficiency ηe, bypass opening ξ _b and coefficient of performance The block diagram which shows the structure of the refrigerating-cycle apparatus of 2nd Embodiment. The block diagram which shows the structure of the refrigeration cycle apparatus of 3rd Embodiment. The block diagram which shows the structure of the refrigerating-cycle apparatus of 4th Embodiment. The block diagram which shows the structure of the refrigerating-cycle apparatus of 5th Embodiment. Detailed longitudinal sectional view of the expander-integrated compressor shown in the block diagram of FIG. Explanatory drawing of operation of expansion mechanism Explanatory drawing following FIG. 16A Illustration of pressure drop due to phase change delay The block diagram which shows the structure of the refrigerating-cycle apparatus of 6th Embodiment.

Explanation of symbols

100A, 100B Expander-integrated compressor 120 Compression mechanism 127 Shaft 130 Expansion mechanism 132 First cylinder 133 Middle plate 134 Second cylinder 136 First piston 137 Second piston 138 First vane 141 Second vane 140, 144b Suction side space 144a, 143 Discharge side space 145 Communication hole 180 Electric motor 300A, 300B, 300C, 300D, 300E, 300F Refrigeration cycle device 301 Main refrigerant circuit 302 Bypass circuit 305 Controller 311 First temperature sensor 313 Second temperature sensor 315 Third temperature sensor 310 Radiator 320 Evaporator 330 Main Piping 350 Flow Control Valve 360 Bypass Piping

Claims (10)

A compressor for compressing the refrigerant;
A radiator that dissipates heat of the refrigerant compressed by the compressor;
An expander for expanding the refrigerant radiated by the radiator;
An evaporator for evaporating the refrigerant expanded by the expander;
A part of the refrigerant before being compressed by the compressor and radiating heat by the radiator is bypassed to the path from the radiator to the expander or the expander without flowing into the radiator. The starting end is connected to the compressor or a path from the compressor to the radiator so as to join the refrigerant before expansion radiated by the radiator or the refrigerant in the expansion process, and the terminal end is the expander or A bypass circuit connected to a path from the radiator to the expander;
A refrigeration cycle apparatus comprising: The bypass circuit includes a flow regulator for adjusting the flow rate of the refrigerant flowing through the bypass circuit;
The refrigeration cycle apparatus according to claim 1, further comprising a controller that controls the flow rate regulator so that the coefficient of performance of the refrigeration cycle apparatus approaches a maximum value. The compressor, the radiator, the expander and the evaporator are connected in this order, further comprising a main pipe constituting a main refrigerant circuit together with these elements,
The refrigeration cycle apparatus according to claim 2, wherein the controller controls the flow rate regulator in accordance with a state of the refrigerant in the main refrigerant circuit. The end of the bypass circuit is connected to the main pipe which is a portion between the radiator and the expander of the main refrigerant circuit,
The controller adjusts the flow rate according to the state of the refrigerant after merging, which flows through the main refrigerant circuit from the connection position of the main refrigerant circuit and the end of the bypass circuit toward the expander. The refrigeration cycle apparatus according to claim 3, wherein the refrigeration cycle apparatus is controlled. A temperature sensor that is provided on the main refrigerant circuit between the main refrigerant circuit and the end of the bypass circuit and the expander, and that measures the temperature of the refrigerant after merging;
The refrigeration cycle according to claim 4, wherein the controller estimates a state of the refrigerant at an inlet of the expander using a measurement result of the temperature sensor, and controls the flow rate regulator based on the estimation result. apparatus. The compressor is configured as the compression mechanism of an expander-integrated compressor having a compression mechanism that compresses the refrigerant, an expansion mechanism that expands the refrigerant, and a shaft that connects the compression mechanism and the expansion mechanism.
The refrigeration cycle apparatus according to claim 1, wherein the expander is configured as the expansion mechanism of the expander-integrated compressor. The expander includes a cylinder, a shaft penetrating the inside and outside of the cylinder, a piston attached to the shaft and rotating eccentrically in the cylinder, and a space formed between the cylinder and the piston as a suction side space. And a rotary expander provided with a partition member that partitions into a discharge side space,
The refrigeration cycle apparatus according to claim 1, wherein the bypass circuit is connected to the cylinder so that the refrigerant flowing through the bypass circuit is directly injected into the suction side space. The expander is
A first cylinder;
A shaft penetrating the inside and outside of the first cylinder;
A first piston attached to the shaft and rotating eccentrically in the first cylinder;
A second cylinder disposed concentrically with the first cylinder so as to share the shaft;
A second piston attached to the shaft and rotating eccentrically in the second cylinder;
A first partition member that partitions a space formed between the first cylinder and the first piston into a first suction side space and a first discharge side space;
A second partition member that partitions a space formed between the second cylinder and the second piston into a second suction side space and a second discharge side space;
The first discharge side space and the second suction side space communicate with each other to form a single expansion chamber, and include an intermediate plate that separates the first cylinder and the second cylinder, A multi-stage rotary expander that expands the refrigerant in an expansion chamber;
The refrigeration cycle apparatus according to claim 1, wherein a connection destination of the bypass circuit is determined so that the refrigerant that has flowed through the bypass circuit is directly injected into the expansion chamber. The end of the bypass circuit is connected to the main pipe which is a portion between the radiator and the expander of the main refrigerant circuit,
The controller adjusts the flow rate according to the state of the refrigerant before merging through the main refrigerant circuit from the radiator toward the connection position between the main refrigerant circuit and the end of the bypass circuit. The refrigeration cycle apparatus according to claim 3, wherein the refrigeration cycle apparatus is controlled. A temperature sensor that is provided on the main refrigerant circuit between the radiator and the connection position of the main refrigerant circuit and the end of the bypass circuit, and further measures the temperature of the refrigerant before joining;
The refrigeration cycle according to claim 9, wherein the controller estimates a state of the refrigerant at an inlet of the expander using a measurement result of the temperature sensor, and controls the flow rate controller based on the estimation result. apparatus.

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