JP2008039237A - Refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration cycle device having a good balance between price and performance by solving such problems that it is necessary to design that the design volume ratio between a compression mechanism and an expansion mechanism is set to be smaller to the utmost than a density ratio in the actual operation condition, or increase in manufacturing costs results from providing a flow adjusting valve and the refrigeration cycle device can not be efficiently operated, in the refrigeration cycle device provided with the expansion mechanism recovering power. <P>SOLUTION: In this refrigeration cycle device, the first compression mechanism 11 and the second compression mechanism 13 are connected in parallel, and a service side heat exchanger 14, the expansion mechanism 15 recovering power, and a heat source side heat exchanger 17 are successively connected. The first compression mechanism 11 and a first driving means 19 are connected to each other by a first shaft, and the second compression mechanism 13, the expansion mechanism 15 and a second driving means 12 are connected to each other by a second shaft. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus including an expansion mechanism that recovers power.

  A refrigeration cycle having an expansion mechanism that recovers pressure energy during expansion as power instead of a decompressor has been proposed. In such a refrigeration cycle apparatus, in a refrigeration cycle apparatus having a configuration in which a positive displacement compression mechanism, an expansion mechanism, and a drive unit are connected to one shaft, VC is a cylinder volume of the compression mechanism and VE is a cylinder volume of the expansion mechanism. / VE (design volume ratio) determines the ratio of the volume circulation amount flowing through each of the compression mechanism and the expansion mechanism.

  Further, when the density of the refrigerant at the evaporator outlet (the refrigerant flowing into the compression mechanism) is DC and the density of the refrigerant at the radiator outlet (the refrigerant flowing into the expansion mechanism) is DE, the mass flowing through each of the compression mechanism and the expansion mechanism Since the circulation amounts are equal, the relationship “VC × DC = VE × DE”, that is, “VC / VE = DE / DC” is established. Since VC / VE (design volume ratio) is a constant determined at the time of designing the device, the refrigeration cycle tries to balance so that DE / DC (density ratio) is always constant. (Hereafter, this is referred to as “constant density ratio constant”.)

  However, the usage conditions of the refrigeration cycle equipment are not necessarily constant. Therefore, if the design volume ratio assumed at the time of design differs from the density ratio in the actual operating state, the best refrigeration It becomes difficult to adjust to the cycle.

  Therefore, a configuration and a control method for adjusting to the best refrigeration cycle by providing a bypass flow path for bypassing the expansion mechanism and controlling the refrigerant circulation amount flowing into the expansion mechanism have been proposed (for example, see Patent Document 1). ).

  Alternatively, there has been proposed a refrigeration cycle apparatus in which a main compression mechanism coupled to a driving means by a shaft and an auxiliary compression mechanism coupled to an expansion mechanism by a shaft are connected in series to constitute a refrigeration cycle (for example, Patent Document 2). reference).

  That is, in this refrigeration cycle apparatus, the refrigerant discharged from the auxiliary compression mechanism that is driven by the recovery power of the expansion mechanism is sucked into the main compression mechanism that is driven by the driving means and further compressed. The compressed refrigerant is radiated by a radiator (condenser) and then decompressed by an expansion mechanism. The recovered power at the time of decompression becomes the driving force of the auxiliary compressor connected by the shaft.

  The depressurized refrigerant absorbs heat in the evaporator and is again sucked into the auxiliary compression mechanism. In addition, a refrigeration cycle apparatus has been proposed in which a main compression mechanism connected to a driving means by a shaft and an auxiliary compression mechanism connected to an expansion mechanism by a shaft are connected in parallel to form a refrigeration cycle (for example, Patent Document 3). reference).

  That is, in this refrigeration cycle apparatus, both the refrigerant discharged from the auxiliary compression mechanism driven by the recovery power of the expansion mechanism and the refrigerant discharged from the main compression mechanism driven by the driving means are both radiators (condensers). After radiating heat, the pressure is reduced by the expansion mechanism. The recovered power at the time of decompression becomes the driving force of the auxiliary compressor connected by the shaft. The depressurized refrigerant absorbs heat in the evaporator and is again sucked into the main compression mechanism and the auxiliary compression mechanism.

  However, since the refrigeration cycle apparatuses of Patent Documents 2 and 3 are composed of a main compression mechanism connected to the driving means by a shaft and an auxiliary compression mechanism connected to the expansion mechanism by a shaft, the refrigeration cycle devices can be arbitrarily expanded. The rotation speed of the mechanism or auxiliary compression mechanism cannot be adjusted. Therefore, the best refrigeration cycle cannot be adjusted only by the expansion mechanism.

For this reason, for example, in Patent Document 3 described above, the flow rate adjustment valve is provided in the discharge side refrigerant flow path of the auxiliary compression mechanism, and the auxiliary compression mechanism is reduced by reducing the refrigerant circulation amount discharged by the auxiliary compression mechanism by the flow rate adjustment valve. A configuration and a control method have been proposed in which a load is applied to the mechanism and the expansion mechanism to adjust to the best refrigeration cycle.
JP 2001-116371 A JP-A-61-96370 JP-A-4-340062

  However, in Patent Document 1, when the density ratio in the actual operation state is smaller than the design volume ratio, a configuration in which the refrigerant can be adjusted to the best refrigeration cycle by flowing the refrigerant through the bypass passage that bypasses the expander. In the case where the density ratio in the actual operation state is larger than the design volume ratio, there is no description about the configuration and the control method that can be adjusted to the best refrigeration cycle.

Therefore, in order to perform an efficient refrigeration cycle operation, the design volume ratio needs to be designed to be as small as possible than the density ratio in the actual operation state. For example, taking the case of a CO ₂ heat pump water heater as an example, under standard operating conditions, the suction density of the compression mechanism is about 100 kg / m ³ and the suction density of the expansion mechanism is about 800 kg / m ^3. The volume ratio is about 8.

  That is, it is necessary to design the cylinder volume (VE) of the expansion mechanism as about 1/8 of the cylinder volume (VC) of the compression mechanism. This means that, for example, if the cylinder volume (VC) of the compression mechanism is about 8 cc, the cylinder volume (VE) of the expansion mechanism needs to be designed to be about 1 cc.

  In this case, when manufacturing the cylinder of the expansion mechanism, fine processing is required, which causes an increase in manufacturing cost or a decrease in volumetric efficiency of the expansion mechanism. For this reason, unless a cost is applied, the refrigeration cycle cannot be brought into an optimum state, and there is a problem that the refrigeration cycle apparatus cannot be efficiently operated.

  On the other hand, for example, if the cylinder volume (VE) of the expansion mechanism is designed to be about 3 cc, it is necessary to design the cylinder volume (VC) of the compression mechanism to be about 24 cc. In this case, it is necessary to enlarge the driving means in order to compensate for an insufficient output of the driving means connected to the compression mechanism, which causes an increase in manufacturing cost. For this reason, unless a cost is applied, the refrigeration cycle cannot be brought into an optimum state, and there is a problem that the refrigeration cycle apparatus cannot be efficiently operated.

  Alternatively, in the refrigeration cycle apparatus constituted by the main compression mechanism connected to the driving means by the shaft and the auxiliary compression mechanism connected to the expansion mechanism by the shaft as in Patent Documents 2 and 3, the expansion mechanism or the auxiliary is arbitrarily set. Since the rotation speed of the compression mechanism cannot be adjusted, the refrigeration cycle cannot be brought into an optimal state, and there has been a problem that the refrigeration cycle apparatus cannot be operated efficiently.

  Moreover, even if a flow rate adjusting valve is provided in the discharge side refrigerant flow path of the auxiliary compression mechanism as in Patent Document 3, the refrigerant circulation amount discharged by the main compression mechanism and the auxiliary compression mechanism, such as when the refrigeration cycle apparatus is started up When the amount is small, it becomes difficult to further reduce the refrigerant circulation amount discharged from the auxiliary compression mechanism by the flow rate adjusting valve and to load the auxiliary compression mechanism and the expansion mechanism. For this reason, the subject that the refrigeration cycle apparatus cannot be operated efficiently has occurred, for example, it takes time to start the refrigeration cycle apparatus.

  Alternatively, providing a flow rate adjusting valve in the discharge side refrigerant flow path of the auxiliary compression mechanism causes an increase in manufacturing cost. For this reason, unless a cost is applied, the refrigeration cycle cannot be brought into an optimum state, and there is a problem that the refrigeration cycle apparatus cannot be efficiently operated.

  In order to solve the above-described conventional problems, a refrigeration cycle apparatus according to the present invention includes a first compression mechanism and a second compression mechanism connected in parallel, a use side heat exchanger, an expansion mechanism that performs power recovery, and a heat source side heat. In the refrigeration cycle apparatus in which the exchangers are sequentially connected, the first compression mechanism and the first drive means are connected by the first shaft, and the second compression mechanism, the expansion mechanism and the second drive means are connected by the second shaft. It is what.

  According to this, since the cylinder volume of the expansion mechanism can be designed large without increasing the compression chamber volume of each compression mechanism, the manufacturing cost can be reduced. Or the malfunction that the volume efficiency of an expansion mechanism falls is also eliminated, a refrigerating cycle is made into the optimal state, and a refrigerating cycle device can be operated efficiently.

  In the refrigeration cycle apparatus of the present invention, the first drive means is operated at a rotational speed equal to or higher than the second drive means. According to this, since the cylinder volume of the expansion mechanism can be designed to be large without increasing the compression chamber volume of each compression mechanism, the manufacturing cost can be reduced. Or the malfunction that the volume efficiency of an expansion mechanism falls is also eliminated, a refrigerating cycle is made into the optimal state, and a refrigerating cycle device can be operated efficiently.

  In the refrigeration cycle apparatus of the present invention, the volumes of the compression chambers of the first compression mechanism and the second compression mechanism are substantially the same. According to this, it becomes possible to share the components of the first compression mechanism and the second compression mechanism and simplify the control method, and further reduce the manufacturing cost.

  In the refrigeration cycle apparatus of the present invention, the first driving means is a first electric motor, the second driving means is a second electric motor, and the first compression mechanism and the first electric motor are accommodated in the first sealed container. The second compression mechanism, the expansion mechanism, and the second electric motor are housed in the second sealed container.

  According to this, it becomes unnecessary to provide a seal part in the penetration part of an airtight container, and also manufacturing cost can be reduced. Alternatively, since the second electric motor can be used as a generator that recovers surplus power as electric power, the manufacturing cost can be further reduced.

  In the refrigeration cycle apparatus of the present invention, the first sealed container and the second sealed container are connected by an oil equalizing pipe. According to this, since the refrigerating machine oil can be prevented from being biased to one of the sealed containers, the refrigeration cycle does not become unstable, and the refrigeration cycle apparatus can be operated efficiently.

  Further, the refrigeration cycle apparatus of the present invention adjusts the rotation speed of the second drive means to thereby adjust the high-pressure side pressure of the refrigeration cycle, the discharge temperature of the first compression mechanism or the second compression mechanism, the first compression mechanism or the second compression mechanism. Any one of the suction superheat degrees of the compression mechanism is adjusted.

  According to this, the amount of circulating refrigerant flowing through the expansion mechanism can be adjusted to a desired high-pressure side pressure, so that the refrigeration cycle apparatus can be operated efficiently. Moreover, since the load is applied to the expansion mechanism in a wider operating range than before by reducing the rotation speed of the second electric motor, the refrigeration cycle apparatus can be operated efficiently.

  Moreover, the refrigerating cycle apparatus of this invention adjusts the capability of a utilization side heat exchanger by adjusting the rotation speed of a 1st drive means. According to this, even if the rotation speed of a 2nd compression mechanism changes, the required capability in a utilization side heat exchanger is securable.

  The refrigeration cycle apparatus of the present invention is a refrigeration cycle apparatus having an expansion mechanism for recovering power, and it is not necessary to design the cylinder volume of the expansion mechanism to be very small compared to the cylinder volume of the compression mechanism. It is possible to provide a refrigeration cycle apparatus capable of efficient operation while preventing an increase in the manufacturing cost of the apparatus, that is, a refrigeration cycle apparatus having a good balance between price and performance.

  Alternatively, a flow rate adjustment valve or the like for controlling the refrigeration cycle to the optimum state is unnecessary, and a refrigeration cycle apparatus that can be operated efficiently while preventing an increase in manufacturing cost of the refrigeration cycle apparatus, that is, a price And a refrigeration cycle apparatus with a good balance of performance can be provided.

  A first invention is a refrigeration cycle apparatus in which a first compression mechanism and a second compression mechanism are connected in parallel, and a use side heat exchanger, an expansion mechanism that performs power recovery, and a heat source side heat exchanger are sequentially connected. The first compression mechanism and the first drive means are connected by a first shaft, and the second compression mechanism, the expansion mechanism and the second drive means are connected by a second shaft, and the cylinder volume of the expansion mechanism is increased. Since it can be designed, the manufacturing cost can be reduced. Or the malfunction that the volume efficiency of an expansion mechanism falls is also eliminated, a refrigerating cycle is made into the optimal state, and a refrigerating cycle device can be operated efficiently.

  In the second aspect of the invention, the rotation speed of the first drive means is operated at a speed higher than the rotation speed of the second drive means, and the cylinder volume of the expansion mechanism can be designed to be large, so that the manufacturing cost can be reduced. . Or the malfunction that the volume efficiency of an expansion mechanism falls is also eliminated, a refrigerating cycle is made into the optimal state, and a refrigerating cycle device can be operated efficiently.

  According to a third aspect of the invention, the compression chambers of the first compression mechanism and the second compression mechanism have substantially the same volume, and components of the first compression mechanism and the second compression mechanism are shared and a control method is provided. Simplification is possible and the manufacturing cost can be further reduced.

  According to a fourth aspect of the invention, the first driving means is a first electric motor, the second driving means is a second electric motor, the first compression mechanism and the first electric motor are accommodated in the first sealed container, Since the compression mechanism, the expansion mechanism, and the second electric motor are housed in the second sealed container, there is no need to provide a seal portion in the penetrating portion of the sealed container, and the manufacturing cost can be further reduced. Alternatively, since the second electric motor can be used as a generator that recovers surplus power as electric power, the manufacturing cost can be further reduced.

  In the fifth aspect of the invention, the first sealed container and the second sealed container are connected by an oil equalizing pipe, and the refrigerating machine oil can be prevented from being biased to one of the sealed containers, so that the refrigeration cycle is unstable. The refrigeration cycle apparatus can be operated efficiently.

  According to a sixth aspect of the present invention, by adjusting the rotational speed of the second drive means, the high-pressure side pressure of the refrigeration cycle, the discharge temperature of the first compression mechanism or the second compression mechanism, the suction of the first compression mechanism or the second compression mechanism One of the degrees of superheat is adjusted, and the amount of refrigerant circulating through the expansion mechanism can be adjusted to a desired high-pressure side pressure, so that the refrigeration cycle apparatus can be operated efficiently. Moreover, since the load is applied to the expansion mechanism in a wider operating range than before by reducing the rotation speed of the second electric motor, the refrigeration cycle apparatus can be operated efficiently.

  7th invention adjusts the capability of a utilization side heat exchanger by adjusting the rotation speed of a 1st drive means, and even if the rotation speed of a 2nd compression mechanism changes, utilization side heat exchange The necessary ability in the vessel can be secured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment. For example, in the following embodiment, a hot water heater will be described as an example, but the present invention is not limited to the hot water heater, and may be an air conditioner or the like.
(Embodiment 1)
A refrigeration cycle apparatus according to a first embodiment of the present invention will be described with reference to a schematic configuration diagram shown in FIG. The refrigeration cycle apparatus in FIG. 1 includes a refrigerant circuit A and a fluid circuit B. The refrigerant circuit A includes a first compression mechanism 11 driven by a first electric motor 10 as first driving means, a second compression mechanism 13 driven by a second electric motor 12 as second driving means, and utilization side heat. It comprises a refrigerant flow path 14a of a hot water supply heat exchanger (radiator) 14 as an exchanger, an expansion mechanism 15 for recovering power, an evaporator 17 as a heat source side heat exchanger, and the like.

  Both the first compression mechanism 11 and the second compression mechanism 13 are configured to suck the refrigerant flowing out of the evaporator 17 and discharge the compressed refrigerant to the radiator 14. The first electric motor 10 and the first compression mechanism 11 are connected by a first shaft 20 and are stored in a first sealed container 30. The second motor 12, the second compression mechanism 13, and the expansion mechanism 15 are connected by a second shaft 21 and are stored in a second sealed container 31.

  Further, the first airtight container 30 and the second airtight container 31 are connected to each other at positions where the refrigerating machine oil stays in the respective containers by an oil equalizing pipe 32. In addition, the refrigeration cycle apparatus uses the discharge temperature of the blower (fan) 16, the first compression mechanism 11, or the second compression mechanism 13 as a heat source side fluid conveyance means for conveying a fluid (for example, outside air) to the evaporator 17. And a discharge temperature detecting means 40 for detecting.

  The discharge temperature detecting means 40 is, for example, a temperature thermistor provided on a pipe from the discharge of the first compression mechanism 11 or the second compression mechanism 13 to the inlet of the refrigerant flow path 14a of the radiator 14 to detect the temperature of the pipe. It is.

  Further, the second motor target rotation speed calculation means 41 for calculating the target rotation speed of the expansion mechanism 15 according to the detection value of the discharge temperature detection means 40, that is, the target rotation speed of the second motor 12, and the second motor target. A second motor rotation speed operation means 42 for operating the rotation speed of the second motor 12 according to the second motor target rotation speed calculated by the rotation speed calculation means 41 is provided.

  Further, the use side heat exchanger capacity calculating means 43 is a target boiling point set by the outside air temperature or the incoming water temperature detected by the outside air temperature detecting means (not shown), the incoming water temperature detecting means (not shown), or the like. The required capacity of the use side heat exchanger 14 is calculated from the upper temperature (the temperature of the fluid (for example, hot water) stored in the hot water supply tank 61 or the target value of the fluid outlet temperature of the radiator 14). The first motor target rotational speed calculating means 44 includes the necessary capacity of the usage-side heat exchanger 14 calculated by the usage-side heat exchanger capacity calculating means 43 and the second motor 12 operated by the second motor rotational speed operating means 42. Based on the rotational speed, the rotational speed of the first electric motor 10 is calculated.

  The first motor rotation speed operation means 45 operates the rotation speed of the first motor 10 based on the first motor target rotation speed calculated by the first motor target rotation speed calculation means 44.

  On the other hand, the fluid circuit B includes a water supply pump 60 serving as a use-side fluid transfer means, a fluid flow path 14b of the radiator 14, a hot water supply tank 61, and the like.

Next, the operation | movement at the time of the driving | operation of the refrigerating-cycle apparatus comprised as mentioned above is demonstrated. In the refrigerant circuit A, carbon dioxide (CO ₂ ), which is a refrigerant, is converted into a critical pressure by the first compression mechanism 11 driven by the first driving means 10 and the second compression mechanism 13 driven by the second driving means 12. Compress to a pressure higher than The refrigerant discharged from the first compression mechanism 11 and the second compression mechanism 13 is mixed and flows into the refrigerant flow path 14 a of the radiator 14. When these refrigerants flow through the refrigerant flow path 14a of the radiator 14, they are radiated to the fluid (for example, water) flowing through the fluid flow path 14b and cooled.

  Thereafter, the refrigerant is depressurized by the expansion mechanism 15 and becomes a low-temperature low-pressure gas-liquid two-phase state. At this time, the expansion mechanism 15 converts the pressure energy of the refrigerant into power, and the power is used as power for assisting the second drive unit 12 to drive the second compression mechanism 13 via the second shaft 21. It is done.

  Thus, COP can be improved by recovering pressure energy at the time of expansion as power and using it as compression power. The refrigerant decompressed by the expansion mechanism 15 is supplied to the evaporator 17. In the evaporator 17, the refrigerant is heated by the outside air sent by the blower (fan) 16 and enters a gas-liquid two-phase or gas state.

  These refrigerants are divided into two refrigerants, the refrigerant sucked into the first compression mechanism 11 and the refrigerant sucked into the second compression mechanism 13, and again sucked into the first compression mechanism 11 and the second compression mechanism 13. Is done.

  On the other hand, in the fluid circuit B, the water sent from the bottom of the hot water supply tank 61 to the fluid flow path 14b of the radiator 14 by the water supply pump 60 is heated by the refrigerant flowing through the refrigerant flow path 14a, and becomes hot hot water. Is stored from the top of the hot water supply tank 61. By repeating such an operation, the refrigeration cycle apparatus of the present embodiment can be used as a hot water heater.

  Further, it is desirable that the first drive means 10 be operated at a rotational speed equal to or higher than the second drive means 12. It is desirable that the compression chambers of the first compression mechanism 11 and the second compression mechanism 13 have substantially the same volume.

The effects of the refrigeration cycle apparatus having such a configuration will be described below. The cylinder volume of the first compression mechanism 11 is VC ₁ , the cylinder volume of the second compression mechanism 13 is VC ₂ , the cylinder volume of the expansion mechanism 15 is VE, the rotation speed of the first drive means 10 is Hz ₁ , and the second drive means 12. Hz 2 the rotational speed of the _evaporator 17 the density of the refrigerant at the outlet (the first compression mechanism 11, and the density of refrigerant flowing into the second compression mechanism 13) to DC, the density of the refrigerant in the radiator 14 outlet (expansion mechanism DE is the density of the refrigerant flowing into 15), and the refrigerant circulating through the expansion mechanism 15 and the mass circulation amount of the refrigerant combined with the refrigerant discharged from the first compression mechanism 11 and the refrigerant discharged from the second compression mechanism 13 respectively. Since the mass circulation amount is equal, “(VC ₁ × Hz ₁ + VC ₂ × Hz ₂ ) × DC = VE × Hz ₂ × DE”, that is, “DE / DC = (VC ₁ × Hz ₁ + VC ₂ × Hz) ₂ ) / (VE × Hz ₂ ) ”is established.

Here, if the rotation speed of the first drive means 10 and the rotation speed of the second drive means 12 are equal, that is, “Hz ₁ = Hz ₂ ”, then “DE / DC = (VC ₁ + VC ₂ ) / VE”. Is established. For example, in the case of a CO ₂ heat pump water heater having a design volume ratio of about 8, the cylinder volume (VE) of the expansion mechanism 15 is the sum of the cylinder volume of the first compression mechanism 11 and the second compression mechanism 13 (VC ₁ + VC may be designed to be about 1/8 of _2), which, for example, a cylinder volume of the first compression mechanism 11 _(VC 1), cylinder volume of the second compression mechanism 13 (VC ₂₎ together, if at about 8cc For example, the cylinder volume (VE) of the expansion mechanism 15 may be designed to be about 2 cc.

Thus, the cylinder volume of the first compression mechanism 11 _(VC 1), without increasing than the cylinder volume a conventional (VC ₂₎ of the second compression mechanism 13, large cylinder volume of the expansion mechanism 15 (VE) Therefore, the cost increase in manufacturing the expansion mechanism 15 can be reduced as compared with the conventional configuration. Furthermore, since the cylinder volume can be designed to be large, the problem that the volume efficiency of the expansion mechanism is reduced can be solved, the refrigeration cycle can be brought into an optimum state, and the refrigeration cycle apparatus can be operated efficiently.

Conversely, for example, if the cylinder volume (VE) of the expansion mechanism 15 is designed to be about 3 cc, the cylinder volume of the first compression mechanism 11 and the sum (VC ₁ + VC ₂ ) of the second compression mechanism 13 is designed to be about 24 cc. it is sufficient, for example, a cylinder volume of the first compression mechanism 11 _(VC 1), cylinder volume of the second compression mechanism 13 (VC ₂₎ together, it is only necessary to a 12 cc, the first compression mechanism in comparison with the conventional configuration 11, the cylinder volume (VC ₁ ) of the second compression mechanism 13 and the cylinder volume (VC ₂ ) of the second compression mechanism 13 do not need to be increased. The necessity of enlarging the driving means to compensate for the output shortage of the two driving means 12 is reduced as compared with the conventional configuration, and an increase in manufacturing cost can be reduced.

  Furthermore, the problem that the first drive means 10 and the second drive means 12 that have been problems in the prior art are also insufficient is solved, the refrigeration cycle is brought into an optimal state, and the refrigeration cycle apparatus can be operated efficiently.

Further, from the relationship of “DE / DC = (VC ₁ × Hz ₁ + VC ₂ × Hz ₂ ) / (VE × Hz ₂ )”, if “Hz ₁ > Hz ₂ ”, the cylinder volume of the expansion mechanism 15 is further increased. Since (VE) can be designed to be large, the above-described effect is great.

Furthermore, each of the compression chamber volume of the first compression mechanism 11 and the second compression mechanism 13 are substantially the same, i.e., by the "VC 1 ₌ VC _2", the first compression mechanism 11 and the second compression mechanism The 13 components can be shared, and the manufacturing cost can be further reduced.

  In the present embodiment, the first compression mechanism 11 and the first electric motor 10 as the first drive means are housed in the first sealed container 30, and the second compression mechanism 13, the expansion mechanism 15, and the second drive means. Since the second electric motor 12 is housed in the second sealed container 31, the first shaft 20 that connects the first compression mechanism 11 and the first electric motor 10, and the second compression mechanism 12 and the expansion. Since there is no need to pass through the first sealed container 30 or the second sealed container 31 through the second shaft 21 that connects the mechanism 15 and the second electric motor 13, the refrigerant and the atmosphere do not mix in the penetrating portion of the sealed container. Therefore, it is not necessary to provide a sealing portion, and the manufacturing cost can be reduced. Or since the 2nd drive means 12 is a 2nd electric motor, even when the collection motive power of the expansion mechanism 15 exceeds the drive force of the 2nd compression mechanism 13, it can utilize also as a generator which collects surplus motive power as electric power. Therefore, the manufacturing cost can be further reduced.

  In the present embodiment, since the first sealed container 30 and the second sealed container 31 are connected by the oil equalizing pipe 32, the refrigerating machine oil sealed in the first sealed container 30 and the second sealed container 31 is , Since it can be prevented from being biased to one of the sealed containers, the refrigeration cycle can be prevented from becoming unstable, and the refrigeration cycle apparatus can be operated efficiently.

In addition, it is possible to prevent the refrigeration cycle from becoming more unstable by connecting the upper parts of the first sealed container 30 and the second sealed container 31 above the position where the refrigerating machine oil stays with the pressure equalizing pipe 33. And more desirable.
(Embodiment 2)
In the second embodiment of the present invention, a control method capable of operating the refrigeration cycle apparatus efficiently is added to the first embodiment. A refrigeration cycle apparatus according to a second embodiment of the present invention will be described with reference to the schematic configuration diagram of FIG. 1 and the flowchart shown in FIG. In the control of the present embodiment, the rotational speed control of the first electric motor 10 as the first driving means and the second electric motor 12 as the second driving means is performed based on the discharge temperature that can be measured relatively inexpensively.

  During operation of the refrigeration cycle apparatus, the use side heat exchanger capacity calculating means 43 detects the outside air temperature, the incoming water temperature, the user, etc. detected by the outside air temperature detecting means (not shown), the incoming water temperature detecting means (not shown), etc. Is calculated from the target boiling temperature (the temperature of the hot water stored in the hot water supply tank or the target value of the fluid outlet temperature of the use side heat exchanger 14) set by (100).

Next, the first motor target rotational speed calculation means 44 is operated by the necessary capacity of the usage-side heat exchanger 14 calculated by the usage-side heat exchanger capacity calculation means 43 and the second motor rotational speed operation means 42 described later. Based on the rotational speed of the second electric motor 12, the rotational speed of the first electric motor 10 is calculated (step 110). Next, the first motor rotation speed operation means 45 operates the rotation speed of the first motor 10 based on the first motor target rotation speed (Hz ₁ ) calculated by the first motor target rotation speed calculation means 44 (step 120). ).

  Further, a detection value (discharge temperature: Td) from the discharge temperature detecting means 40 is taken in (step 130). The target discharge temperature (target Td) stored in advance in the ROM or the like is compared with the discharge temperature (Td) captured in step 130 (step 140).

  When the discharge temperature (Td) is lower than the target discharge temperature (target Td), the high-pressure side pressure tends to be lower than the optimum pressure, so the rotation speed (Hz2) of the expansion mechanism 15, that is, the second electric motor 12 is set. By operating in the decreasing direction (step 150), the refrigerant circulation amount flowing through the expansion mechanism 15 is decreased, and the high-pressure side pressure and the discharge temperature are increased.

Conversely, when the discharge temperature (Td) is higher than the target discharge temperature (target Td) in step 140, the high pressure side pressure tends to be higher than the optimum pressure, so that the expansion mechanism 15, that is, the second electric motor 12 The rotational speed (Hz ₂ ) is operated in the increasing direction (step 160), the amount of refrigerant circulating through the expansion mechanism 15 is increased, and the high-pressure side pressure and the discharge temperature are decreased.

When the rotation speed (Hz ₂ ) of the second electric motor 12 is manipulated in step 150 or step 160, not only the rotation speed of the expansion mechanism 15 but also the rotation speed of the second compression mechanism 13 changes. For this reason, it returns to step 110, and again the required capacity | capacitance of the utilization side heat exchanger 14 which the utilization side heat exchanger capacity | capacitance calculation means 43 calculated, and rotation of the 2nd electric motor 12 which the 2nd motor rotation speed operation means 42 operated. The change in the refrigerant circulation amount of the second compression mechanism 13 due to the change in the rotation speed of the second electric motor 12 is adjusted by calculating the rotation speed of the first electric motor 10 based on the number. As described above, control is performed in which the rotation speed of the first electric motor 10 and the rotation speed of the second electric motor 12 are linked.

  Thereby, in the refrigeration cycle apparatus having the configuration of the present embodiment, the refrigerant circulation amount flowing through the expansion mechanism 15 is adjusted by adjusting the rotation speed of the second electric motor 12 without providing a flow rate adjusting valve as in the prior art. Since the pressure can be adjusted to a desired high pressure side pressure, the refrigeration cycle apparatus can be operated efficiently. Further, even when the refrigerant circulation amount is small and a load cannot be applied by the flow rate adjustment valve as in the conventional case, the load is applied more than before by reducing the rotation speed of the second electric motor 12, so that the refrigeration cycle apparatus can be efficiently used. I can drive.

  Further, after adjusting the rotation speed of the second electric motor 12, the rotation speed of the second compression mechanism 13 is adjusted because the rotation speed of the first compression mechanism 11 is adjusted again from the necessary capacity of the use side heat exchanger 14. Even if the number changes, the necessary capacity in the use side heat exchanger 14 can be secured.

  Furthermore, when the volume of each compression chamber of the 1st compression mechanism 11 and the 2nd compression mechanism 13 is substantially the same, since a control method can be simplified and manufacturing cost can be reduced further, it is desirable.

  That is, in this case, in order to maintain the same performance in the use-side heat exchanger 14, for example, when the rotational speed of the first electric motor 10 is reduced by 2 Hz in step 150, the second electric motor 12 in step 110. The target rotational speed of the second electric motor 12 can be decreased by 2 Hz in step 110. In contrast, if the rotational speed of the first electric motor 10 is increased by 2 Hz in step 160, the target rotational speed of the second electric motor 12 can be decreased by 2 Hz. Therefore, the calculation in step 110 can be simplified.

  The rotation speed of the second motor 12 has been described as being obtained from the operation value of the second motor rotation speed operation means 42. However, the actual rotation speed may be measured by a sensor or the like, or the second motor target. It is good also as what is calculated | required from the target value of the rotation speed 41. FIG. Further, in order to increase the stability of the state of the refrigeration cycle, control may be performed by adding or subtracting a minute value to the target discharge temperature (target Td) so that the discharge temperature falls within a certain temperature range.

  Furthermore, in the control of the present embodiment, it has been described that the number of revolutions of the second electric motor 12 is controlled by the discharge temperature. However, the high pressure side pressure may be directly detected and controlled using the value, Or you may control using the detected value which detected the temperature on a refrigerating-cycle apparatus, and the calculated value using those detected values. For example, the control may be performed using the suction superheat degree of the first compression mechanism 11 or the second compression mechanism 13 or the superheat degree of the outlet of the evaporator 17.

  The refrigeration cycle apparatus of the present invention, in the refrigeration cycle apparatus provided with an expansion mechanism that performs power recovery, eliminates the need to design the cylinder volume of the expansion mechanism with a very small volume compared to the cylinder volume of the compression mechanism, or A flow control valve for controlling the refrigeration cycle to the optimum state is not necessary, and a refrigeration cycle device that can operate efficiently while preventing an increase in the manufacturing cost of the refrigeration cycle device. Since it becomes a well-balanced refrigeration cycle apparatus, it can be applied to uses such as a water heater and an air conditioner equipped with the expansion mechanism 15.

The block diagram which shows the refrigerating-cycle apparatus in Embodiment 1 of this invention. Flowchart of control of refrigeration cycle apparatus in Embodiment 2 of the present invention

Explanation of symbols

10 First driving means (first electric motor)
11 1st compression mechanism 12 2nd drive means (2nd electric motor)
13 Second compression mechanism 14 Use side heat exchanger (heat radiator, heat exchanger for hot water supply)
14a Refrigerant flow path 14b Fluid flow path 15 Expansion mechanism 16 Heat source side fluid transfer means (blower, fan)
17 Heat source side heat exchanger (evaporator)
DESCRIPTION OF SYMBOLS 20 1st axis | shaft 21 2nd axis | shaft 30 1st airtight container 31 2nd airtight container 32 Oil equalizing pipe 33 Pressure equalizing pipe 40 Discharge temperature detection means 41 2nd electric motor target rotational speed calculating means 42 2nd electric motor rotational speed operating means 43 Utilization Side heat exchanger capacity calculation means 44 First motor target rotation speed calculation means 45 First motor rotation speed operation means 60 Use side fluid transfer means (water supply pump)
61 Hot water tank A Refrigerant circuit B Fluid circuit

Claims (7)

In the refrigeration cycle apparatus in which at least a first compression mechanism and a second compression mechanism are connected in parallel, and a use side heat exchanger, an expansion mechanism for recovering power, and a heat source side heat exchanger are sequentially connected, the first compression mechanism And a first drive means are connected by a first shaft, and the second compression mechanism, the expansion mechanism, and the second drive means are connected by a second shaft. 2. The refrigeration cycle apparatus according to claim 1, wherein the first driving unit is operated at a rotational speed equal to or higher than the rotational speed of the second driving unit. The refrigeration cycle apparatus according to claim 1, wherein the compression chambers of the first compression mechanism and the second compression mechanism have substantially the same volume. The first driving means is a first electric motor, and the second driving means is a second electric motor, and the first compression mechanism and the first electric motor are housed in a first sealed container, and the second compression The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the mechanism, the expansion mechanism, and the second electric motor are housed in a second sealed container. The refrigeration cycle apparatus according to claim 4, wherein the first sealed container and the second sealed container are connected by an oil equalizing pipe. By adjusting the rotation speed of the second drive means, the high pressure side pressure of the refrigeration cycle, the discharge temperature of the first compression mechanism or the second compression mechanism, the suction overheating of the first compression mechanism or the second compression mechanism The refrigeration cycle apparatus according to any one of claims 1 to 5, wherein any one of the degrees is adjusted. The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein the capacity of the use-side heat exchanger is adjusted by adjusting the rotational speed of the first drive means.

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