JP2014095510A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a performance coefficient of a refrigeration cycle device by reducing pressure loss when discharging a cooling medium from a compressor.SOLUTION: By controlling throttle opening of an expansion valve 3 for intermediate pressure of a refrigeration cycle device configuring a gas injection cycle, pressure of an intermediate pressure cooling medium flowing into a compression chamber from an injection port 1b is adjusted in such a manner that a cooling medium pressure in the compression chamber becomes closer to a pressure of a cooling medium on a high pressure side Pd of the cycle, when the compression chamber of a compressor 1 communicates with a discharge port 1c. Thereby, backflow of the cooling medium on a high pressure side into the compression chamber via the discharge port 1c can be suppressed, and a check valve for a discharge port can be eliminated. Therefore, a performance coefficient of a refrigeration cycle device can be improved by reducing pressure loss when discharging a cooling medium from the compressor.

Description

  The present invention relates to a refrigeration cycle apparatus constituting a gas injection cycle.

  Conventionally, a gas injection cycle (economizer refrigeration cycle) is known as a cycle configuration for improving the capacity or coefficient of performance (COP) of a vapor compression refrigeration cycle. In this type of gas injection cycle, it is possible to improve the performance or coefficient of performance (COP) of the refrigeration cycle by injecting the intermediate-pressure gas-phase refrigerant generated on the cycle side into the refrigerant in the pressurizing process in the compression chamber of the compressor. .

  Further, as a compressor applied to a refrigeration cycle apparatus constituting a gas injection cycle, for example, as disclosed in Patent Document 1, a suction port for sucking low-pressure refrigerant into a compression chamber, and a compression process in the compression chamber There is known one having an injection port for joining an intermediate-pressure gas-phase refrigerant to this refrigerant and a discharge port for discharging a high-pressure refrigerant compressed in a compression chamber.

  In addition, the compressor of Patent Document 1 includes a check valve for an injection port for preventing the refrigerant from flowing back from the compression chamber to the outside of the compressor via the injection port, and the refrigerant of the compressor. Two check valves for the discharge port are provided to prevent backflow from the outside to the compression chamber via the discharge port.

JP-A-11-107950

  However, providing two check valves as in the compressor of Patent Document 1 increases the number of parts and the number of assembling steps of the compressor and increases the manufacturing cost of the compressor. Furthermore, since the check valve for the discharge port increases the pressure loss when the refrigerant is discharged from the compressor, it causes the drive power of the compressor to increase. Therefore, the check valve for the discharge port tends to be a hindrance when aiming at further improvement of COP.

  In view of the above points, an object of the present invention is to improve the coefficient of performance of a refrigeration cycle apparatus by reducing pressure loss when refrigerant is discharged from a compressor.

The present invention has been devised to achieve the above object, and in the invention according to claim 1, the suction port (1a) for sucking the low-pressure refrigerant into the compression chamber for changing the volume and compressing the refrigerant, the compression A compressor (1) having an injection port (1b) for joining the intermediate pressure refrigerant to the refrigerant in the compression process in the chamber, and a discharge port (1c) for discharging the high-pressure refrigerant compressed in the compression chamber; A heat-dissipating heat exchanger (2) that dissipates the refrigerant discharged from 1c), a heat-dissipating heat exchanger (2), an intermediate-pressure depressurizing means (3) that depressurizes the downstream refrigerant until it becomes an intermediate-pressure refrigerant, The heat-dissipating heat exchanger (2) the low-pressure decompression means (5) for decompressing the downstream refrigerant until it becomes a low-pressure refrigerant, the refrigerant decompressed by the low-pressure decompression means (5) is evaporated, and the suction port ( 1a) Evaporation heat exchanger that flows out to the side ( ) And, further, an intermediate pressure control means for controlling the operation of the intermediate pressure pressure reducing means (3),
The intermediate pressure control means is a refrigeration for controlling the operation of the intermediate pressure reducing means (3) so that the refrigerant pressure in the compression chamber approaches a predetermined pressure when the compression chamber communicates with the discharge port (1c). Features cycle equipment.

  According to this, when the compression chamber communicates with the discharge port (1c), the intermediate pressure control means of the intermediate pressure decompression means (3) is set so that the refrigerant pressure in the compression chamber becomes equal to or higher than a predetermined pressure. Since the operation is controlled, it is possible to prevent the refrigerant on the high pressure side of the cycle from flowing back to the compression chamber via the discharge port (1c).

  Therefore, the structure corresponding to the check valve for the discharge port in the prior art can be eliminated. Thereby, the pressure loss at the time of discharging a refrigerant | coolant from a compressor (1) can be reduced, and since the drive power of a compressor (1) can be reduced, the coefficient of performance of a refrigeration cycle apparatus is improved. Can do. Furthermore, the manufacturing cost of the compressor (1) can be reduced.

  Further, by adopting the high pressure side refrigerant pressure (Pd) of the cycle from the discharge port (1c) to the refrigerant inlet of the intermediate pressure reducing means (3) as the predetermined pressure, the high pressure side refrigerant of the cycle is discharged from the discharge port (1c). ) Can be effectively suppressed from flowing back to the compression chamber.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a whole lineblock diagram of the refrigerating cycle device of a 1st embodiment. It is a flowchart which shows the principal part of the control processing of the refrigerating-cycle apparatus of 1st Embodiment. It is a graph which shows the volume of the compression chamber with respect to the change of the rotation angle of 1st Embodiment, and the refrigerant | coolant pressure change in a compression chamber. It is a whole block diagram of the refrigerating-cycle apparatus of 2nd Embodiment.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. The refrigeration cycle apparatus 10 of the present embodiment is applied to a heat pump type hot water heater, and fulfills a function of heating hot water. Furthermore, the refrigeration cycle apparatus 10 is configured as a gas injection cycle in which the intermediate pressure refrigerant in the cycle is merged with the refrigerant in the pressurization process in the compression chamber of the compressor 1, as shown in the overall configuration diagram of FIG.

  More specifically, the refrigeration cycle apparatus 10 includes a compressor 1, a water-refrigerant heat exchanger 2, an intermediate pressure expansion valve 3, a gas-liquid separator 4, a low pressure expansion valve 5, an outdoor heat exchanger 6, and the like. ing. The compressor 1 sucks refrigerant in the refrigeration cycle apparatus 10 and compresses and discharges the refrigerant. A scroll-type compression mechanism and an electric motor that rotationally drives the compression mechanism are provided inside a housing that forms an outer shell of the compressor 1. Is an electric compressor configured to accommodate

  The scroll-type compression mechanism has a fixed scroll fixed to the housing and a movable scroll connected to the rotating shaft of the electric motor. Further, the fixed scroll is formed with a spiral fixed side tooth portion that protrudes toward the movable scroll side, while the movable scroll protrudes toward the fixed scroll side and meshes with the fixed side tooth portion. A movable side tooth portion is formed.

  And the fixed side tooth part of the fixed scroll and the movable side tooth part of the movable scroll are engaged with each other and contacted at a plurality of places, thereby forming a plurality of compression chambers formed in a crescent shape when viewed from the rotation axis direction. . The compression chamber revolves with the rotation of the rotary shaft of the electric motor, and moves around the rotary shaft while reducing the volume from the outer peripheral side to the central side while compressing the refrigerant.

  The housing of the compressor 1 communicates with the compression chamber moving to the outermost peripheral side and sucks the low-pressure refrigerant from the outside of the housing into the compression chamber. The suction port 1a is at an intermediate position from the outer peripheral side to the center side. High pressure refrigerant is discharged from the compression chamber connected to the compression chamber moved to the injection port 1b for joining the intermediate pressure refrigerant to the refrigerant in the compression process in the compression chamber from the outside of the housing and to the compression chamber moved to the center side. A discharge port 1c is provided.

  Further, the injection port 1b is provided with a check valve for preventing the refrigerant from flowing back from the compression chamber to the outside of the compressor via the injection port. This corresponds to the check valve for the injection port of the prior art. On the other hand, the discharge port 1c of this embodiment is not provided with a configuration corresponding to a check valve for a discharge port according to the prior art.

  The operation (rotation speed) of the electric motor is controlled by a control signal output from a control device described later, and either an AC motor or a DC motor may be adopted. And the refrigerant | coolant discharge capability of the compressor 1 is changed by rotation speed control by this control apparatus. The discharge port 1 c of the compressor 1 is connected to the inlet side of the refrigerant passage of the water-refrigerant heat exchanger 2.

  The water-refrigerant heat exchanger 2 is a heat radiating heat exchanger that radiates the heat of the high-temperature and high-pressure refrigerant discharged from the discharge port 1 c of the compressor 1 to the hot water. The water-refrigerant heat exchanger 2 has a plurality of tubes as refrigerant passages for circulating high-pressure refrigerant, forms water passages between adjacent refrigerant passages (tubes), and supplies hot water in the water passages. A heat exchanger or the like configured by disposing an inner fin or the like that promotes heat exchange with the refrigerant can be employed. The inlet side of the intermediate pressure expansion valve 3 is connected to the outlet side of the refrigerant passage of the water-refrigerant heat exchanger 2.

  The intermediate pressure expansion valve 3 is an intermediate pressure reducing means for reducing the pressure of the high pressure refrigerant downstream of the water-refrigerant heat exchanger 2 until it becomes intermediate pressure refrigerant, and its operation is controlled by a control signal output from the control device. This is an electric expansion valve. The intermediate pressure expansion valve 3 includes an electric variable throttle that includes a valve body that changes the opening degree of the throttle passage that decompresses the refrigerant and an electric actuator that includes a stepping motor that displaces the valve body. A mechanism or the like can be adopted. The inlet side of the gas-liquid separator 4 is connected to the outlet side of the intermediate pressure expansion valve 3.

  The gas-liquid separator 4 is a gas-liquid separation unit that separates the gas-liquid of the intermediate-pressure refrigerant that has been decompressed by the intermediate-pressure expansion valve 3 to be in a gas phase mixed phase state. The above-described injection port 1 b of the compressor 1 is connected to the gas-phase refrigerant outlet of the gas-liquid separator 4. An inlet side of the low-pressure expansion valve 5 is connected to the liquid-phase refrigerant outlet of the gas-liquid separator 4.

  The low-pressure expansion valve 5 is a low-pressure depressurizing unit that depressurizes the intermediate-pressure liquid-phase refrigerant separated by the gas-liquid separator 4 among the refrigerant on the downstream side of the water-refrigerant heat exchanger 2 until it becomes a low-pressure refrigerant. The basic configuration is the same as that of the intermediate pressure expansion valve 3. The refrigerant inlet side of the outdoor heat exchanger 6 is connected to the outlet side of the low pressure expansion valve 5.

  The outdoor heat exchanger 6 is an evaporation heat exchanger that evaporates the low-pressure refrigerant decompressed by the low-pressure expansion valve 5 by exchanging heat with outside air blown from an electric blower fan (not shown). Specifically, the outdoor heat exchanger 6 is configured by arranging a plurality of refrigerant tubes in a skewered manner on a plurality of plate fins for promoting heat exchange, and connecting each refrigerant tube in a meandering manner. A heat exchanger can be used. A suction port 1 a of the compressor 1 is connected to the refrigerant outlet side of the outdoor heat exchanger 6.

  In the refrigeration cycle apparatus 10 of the present embodiment, carbon dioxide is used as the refrigerant, and the pressure of the high-pressure side refrigerant in the cycle from the discharge port of the compressor 1 to the inlet side of the intermediate pressure expansion valve 3 is the criticality of the refrigerant. It constitutes a supercritical refrigeration cycle that exceeds the pressure. Furthermore, the refrigerant is mixed with oil (refrigeration oil) that lubricates each sliding portion inside the compressor 1, and a part of this oil circulates in the cycle together with the refrigerant.

  In addition to the refrigeration cycle apparatus 10, the heat pump type hot water heater is a hot water storage tank for storing hot water heated in the water-refrigerant heat exchanger 2 (specifically, a water passage), a hot water storage tank and water- There are provided a hot water circulating circuit for circulating hot water between the refrigerant heat exchanger 2 and a water pump (none of which is shown) disposed in the hot water circulating circuit for pumping hot water.

  Next, an outline of the electric control unit of the present embodiment will be described. The control device is composed of a well-known microcomputer including a CPU, a ROM, a RAM and the like and its peripheral circuits. On the output side of the control device, the electric motor of the compressor 1, the intermediate pressure expansion valve 3, the low pressure expansion valve 5, the electric blower fan for blowing outside air to the outdoor heat exchanger 6, the water pump of the hot water circulation circuit, etc. Are connected, and the control device controls the operation of these various devices to be controlled.

  On the other hand, on the input side of the control device, a high pressure side pressure sensor as a high pressure side pressure detecting means for detecting the high pressure side refrigerant pressure Pd discharged from the discharge port 1c of the compressor 1, and compression from the injection port 1b of the compressor 1 are compressed. An intermediate pressure side pressure sensor as an intermediate pressure side pressure detecting means for detecting the pressure Pm of the intermediate pressure refrigerant flowing into the machine 1, an intermediate pressure side temperature sensor as an intermediate pressure side temperature detecting means for detecting the temperature Tm of the intermediate pressure refrigerant, a compressor A low pressure side pressure sensor as a low pressure side pressure detecting means for detecting the pressure Ps of the low pressure refrigerant sucked from one suction port 1a; a low pressure side temperature sensor as a low pressure side temperature detecting means for detecting the temperature Ts of the low pressure refrigerant; Sensor groups for controlling various water heaters such as an outside air temperature sensor as an outside air temperature detecting means for detecting Tam are connected, and the detection signals of these sensor groups are Is input to the control device.

  Further, an operation panel (not shown) is connected to the input side of the control device. This operation panel is provided with an operation switch for outputting an operation signal or a stop signal of the heat pump type hot water heater, a temperature setting switch for setting a boiling temperature (target heating temperature) of the hot water supply, and the operation signals of these switches. Is input to the controller.

  The control device of this embodiment is configured such that control means for controlling the electric motor of the compressor 1, the intermediate pressure expansion valve 3 and the like are integrally configured. A configuration (hardware and software) for controlling the operation of the pressure expansion valve 3 is an intermediate pressure control means. Of course, the intermediate pressure control means may be configured by another control device for the control device.

  Next, the operation of the heat pump type water heater of the present embodiment having the above configuration will be described. When an operation signal of a water heater provided on the operation panel is input to the control device in a state where power is supplied from the outside to the heat pump type water heater, control processing (control) stored in the storage circuit in advance by the control device Program).

  More specifically, in the main routine of this control process, the operation signal of the operation panel and the detection signal detected by the above-described sensor group for controlling the water heater are read, and based on the read operation signal and detection signal, Control states (specifically, control signals or control voltages output to the various control target devices) of the various control target devices of the refrigeration cycle apparatus 10 are determined.

  For example, the control signal output to the electric motor of the compressor 1 is stored in the ROM (storage circuit) of the control device based on the hot water temperature setting signal from the operation panel and the outside air temperature Tam detected by the outside air temperature sensor. Determined with reference to the control map. Specifically, the rotational speed (refrigerant discharge capacity) of the compressor 1 is determined to increase as the set temperature is increased by the hot water supply temperature setting signal and the outside air temperature Tam is decreased.

  As for the control signal output to the electric actuator of the intermediate pressure expansion valve 3, when the compression chamber of the compressor 1 communicates with the discharge port 1c, the refrigerant pressure in the compression chamber is changed from the discharge port 1c to the intermediate pressure expansion valve 3. It is determined so as to approach the high-pressure side refrigerant pressure Pd of the cycle leading to the refrigerant inlet. More specifically, it is determined as shown in the flowchart of FIG. The flowchart of FIG. 2 is a control flow executed as a subroutine of the main routine.

  Here, in the compression mechanism that compresses the refrigerant by reducing the volume of the compression chamber, like the scroll type compression mechanism of the present embodiment, the amount of increase in the refrigerant pressure in the compression chamber according to the volume reduction amount of the compression chamber. (Pressure increase amount) can be calculated. Therefore, the refrigerant pressure in the compression chamber when communicating with the discharge port 1c can be calculated based on the refrigerant pressure within the compression chamber when communicating with the injection port 1b.

  Therefore, in this embodiment, as shown in the flowchart of FIG. 2, the control signal output to the electric actuator of the intermediate pressure expansion valve 3 is determined. First, in step S1, the first refrigerant pressure P1 in the compression chamber communicating with the suction port 1a is calculated from the outside air temperature Tam and the low-pressure refrigerant temperature Ts read in the main routine. In addition, when the low pressure side pressure sensor as a low pressure side pressure detection means is provided, you may calculate the 1st refrigerant | coolant pressure P1 using the detected value.

  Furthermore, in step S1, the pressure Pm of the intermediate pressure refrigerant is calculated from the temperature Tm of the intermediate pressure refrigerant read in the main routine. In addition, when the intermediate pressure side pressure sensor as an intermediate pressure side pressure detection means is provided, you may calculate the pressure Pm of an intermediate pressure refrigerant | coolant using the detected value. From the first refrigerant pressure P1 and the intermediate pressure refrigerant pressure Pm calculated as described above, the second refrigerant pressure P2 in the compression chamber communicating with the injection port 1b is calculated. The second refrigerant pressure P2 is a pressure immediately before the communication between the compression chamber and the pipe through which the intermediate-pressure refrigerant flows, and is the maximum pressure in the compression chamber communicating with the injection port 1b.

  In the subsequent step S2, the third refrigerant pressure P3 in the compression chamber just before communicating with the compression chamber or the discharge port 1c when communicating with the discharge port 1c is calculated from the second refrigerant pressure P2 calculated at step S1.

  In step S3, it is determined whether the third refrigerant pressure P3 is lower than the high-pressure side refrigerant pressure Pd detected by the high-pressure side pressure sensor. If it is determined in step S3 that the third refrigerant pressure P3 is lower than the high-pressure side refrigerant pressure Pd, the process proceeds to step S4, and the throttle opening of the intermediate pressure expansion valve 3 is set to a predetermined amount. The control signal is determined so as to increase, and the process returns to the main routine.

  In this way, by increasing the throttle opening of the intermediate pressure expansion valve 3 in step S4, the refrigerant pressure reduction amount in the intermediate pressure expansion valve 3 decreases, and the pressure of the refrigerant flowing into the compression chamber from the injection port 1b increases. To do. As a result, the third refrigerant pressure P3 in the compression chamber immediately before communicating with the discharge port 1c or just before communicating with the discharge port 1c increases and approaches the high-pressure side refrigerant pressure Pd.

  On the other hand, when it is determined in step S3 that the third refrigerant pressure P3 is not lower than the high-pressure side refrigerant pressure Pd, that is, the third refrigerant pressure P3 is equal to or higher than the high-pressure side refrigerant pressure Pd, Proceeding to step S5, a control signal is determined so as to decrease the throttle opening of the intermediate pressure expansion valve 3 by a predetermined amount, and the process returns to the main routine.

  In this way, by reducing the throttle opening degree of the intermediate pressure expansion valve 3 in step S5, the refrigerant pressure reduction amount in the intermediate pressure expansion valve 3 increases, and the pressure of the refrigerant flowing into the compression chamber from the injection port 1b decreases. To do. As a result, the third refrigerant pressure P3 in the compression chamber just before communicating with the discharge port 1c or just before communicating with the discharge port 1c decreases and approaches the high-pressure side refrigerant pressure Pd.

  The control signal output to the electric actuator of the low-pressure expansion valve 5 is determined so that the high-pressure side refrigerant pressure Pd of the refrigeration cycle apparatus 10 becomes the target high pressure. The target high pressure is determined based on the outside temperature Tam and the compressor 1 discharge refrigerant temperature estimated from the refrigerant discharge capacity of the compressor 1 with reference to a control map stored in advance in the ROM of the control device. The coefficient of performance (COP) is determined to be substantially the maximum.

  The control voltage output to the electric blower fan that blows outside air to the outdoor heat exchanger 6 is determined based on the outside air temperature Tam with reference to a control map stored in advance in the ROM of the control device. Moreover, about the control voltage output to the water pump of the hot water circulation circuit, the boiling temperature of hot water flowing out from the water passage of the water-refrigerant heat exchanger 2 is set by the temperature setting switch using a feedback control method or the like. It is determined to approach the set target heating temperature.

  Then, the control signal and the control voltage determined as described above are output to various devices to be controlled. After that, until the operation panel requests to stop the operation of the heat pump water heater, reading the above detection signal and operation signal at every predetermined control cycle → Determining the control state of various control target devices → To various control target devices Control routines such as control voltage and control signal output are repeated.

  Therefore, when the heat pump type water heater of this embodiment is operated, the high-temperature and high-pressure refrigerant discharged from the compressor 1 of the refrigeration cycle apparatus 10 flows into the refrigerant passage of the water-refrigerant heat exchanger 2. The high-temperature and high-pressure refrigerant that has flowed into the refrigerant passage of the water-refrigerant heat exchanger 2 dissipates heat to the hot water flowing through the water passage of the water-refrigerant heat exchanger 2 to lower the enthalpy. Thereby, the hot water is heated, and the heated hot water flows into the hot water storage tank and is stored.

  On the other hand, the high-pressure refrigerant that has flowed out of the water-refrigerant heat exchanger 2 is decompressed by the intermediate-pressure expansion valve 3 until it becomes intermediate-pressure refrigerant, and flows into the gas-liquid separator 4. The intermediate pressure gas-phase refrigerant separated by the gas-liquid separator 4 flows into the compressor 1 from the injection port 1b. On the other hand, the intermediate-pressure liquid-phase refrigerant separated by the gas-liquid separator 4 is decompressed by the low-stage expansion valve 3 until it becomes a low-pressure refrigerant and flows into the outdoor heat exchanger 6.

  The refrigerant flowing into the outdoor heat exchanger 6 absorbs heat from the outside air blown from the blower fan and evaporates. The refrigerant flowing out of the outdoor heat exchanger 6 is sucked from the suction port 1a of the compressor 1 and compressed again.

  The heat pump type hot water heater of the present embodiment operates as described above, and can heat hot water in the water-refrigerant heat exchanger 2 of the refrigeration cycle apparatus 10. Further, since the refrigeration cycle apparatus 10 of the present embodiment constitutes a gas injection cycle, it is possible to improve the heating capacity or the coefficient of performance (COP) of the cycle as compared with the normal refrigeration cycle.

  Furthermore, in the refrigeration cycle apparatus 10 of the present embodiment, as described in the flowchart of FIG. 2, the third refrigerant pressure P3 in the compression chamber just before communicating with the compression chamber or the discharge port 1c when communicating with the discharge port 1c is set. The operation of the intermediate pressure expansion valve 3 is controlled so as to approach the high pressure side refrigerant pressure Pd. Therefore, when the compression chamber communicates with the discharge port 1c, it is possible to prevent the refrigerant on the high-pressure side of the cycle from flowing back to the compression chamber via the discharge port 1c.

  This will be described with reference to the graph of FIG. Here, in the refrigeration cycle apparatus constituting the gas injection cycle including the compressor in which the low stage side volume change rate and the high stage side volume change rate are formed substantially equal, generally, the water-refrigerant heat exchanger 2 is provided. The ratio P2 / P1 of the second refrigerant pressure P2 to the first refrigerant pressure P1 is controlled to about 2 in order to improve the COP of the refrigeration cycle while sufficiently securing the heating capacity of hot water in

  In the conventional refrigeration cycle apparatus in which the ratio P2 / P1 is controlled to about 2 as described above, the refrigerant pressure in the compression chamber when communicating with the discharge port 1c is higher than the high-pressure side refrigerant pressure as shown by the thick broken line in FIG. It becomes lower than Pd. For this reason, it is necessary to provide a check valve on the discharge port side for suppressing the high-pressure side refrigerant of the cycle from flowing back to the compression chamber via the discharge port 1c.

  In contrast, in the present embodiment, the ratio P2 / P1 is set from a general value (specifically, 2) by controlling the operation of the intermediate pressure expansion valve 3 as described in the flowchart of FIG. The value is high (specifically, about 3). Therefore, as shown by the thick solid line in FIG. 3, the second refrigerant pressure P2 can be increased to bring the third refrigerant pressure P3 in the compression chamber when communicating with the discharge port 1c closer to the high-pressure side refrigerant pressure Pd.

  As a result, when the compression chamber communicates with the discharge port 1c, the refrigerant on the high-pressure side of the cycle can be prevented from flowing back to the compression chamber via the discharge port 1c, and the check valve for the discharge port in the prior art The configuration corresponding to can be abolished.

  As a result, the pressure loss when the refrigerant is discharged from the compressor 1 can be reduced, and the space (dead volume) for connecting the portion from the compression chamber to the check valve for the discharge port in the prior art can be reduced. There is no need to perform unnecessary boosting. Therefore, COP can be improved with respect to the refrigerating cycle apparatus which comprises the gas injection cycle of a prior art.

  Further, by eliminating the configuration corresponding to the check valve for the discharge port in the prior art, the number of parts and assembly man-hours of the compressor 1 can be reduced, so that the manufacturing cost of the compressor 1 can be reduced. Can do. As a result, the manufacturing cost of the entire refrigeration cycle apparatus 10 can be reduced.

(Second Embodiment)
In 1st Embodiment, although the example which comprised the refrigerating-cycle apparatus 10 using the gas-liquid separator 4 which is a gas-liquid separation means was demonstrated, in this embodiment, as shown in FIG. The example which employ | adopted internal heat exchanger 7 and comprised the refrigerating-cycle apparatus 10a is demonstrated. In FIG. 4, the same or equivalent parts as those in the first embodiment are denoted by the same reference numerals.

  More specifically, in the refrigeration cycle apparatus 10a of the present embodiment, a branching portion is provided that branches the flow of the high-pressure refrigerant that has finished heat exchange in the water-refrigerant heat exchanger 2. Then, the intermediate pressure expansion valve 3 of the present embodiment reduces the pressure of the one high-pressure refrigerant branched at the branch portion until it becomes an intermediate-pressure refrigerant.

  The internal heat exchanger 7 exchanges heat between the intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve 3 and the other high-pressure refrigerant branched at the branch portion, heats and vaporizes the intermediate-pressure refrigerant, and the other high-pressure refrigerant. It reduces the enthalpy of the refrigerant. Specifically, it is possible to employ a double-pipe heat exchanger or the like in which an inner tube through which an intermediate-pressure refrigerant is circulated is disposed inside an outer tube through which a high-pressure refrigerant is circulated.

  An injection port 1 b of the compressor 1 is connected to the outlet side of the intermediate pressure refrigerant flow path in the internal heat exchanger 7. In the internal heat exchanger 7, the inlet side of the low-pressure expansion valve 5 is connected to the outlet side of the high-pressure refrigerant flow path. That is, the low-pressure expansion valve 5 of the present embodiment reduces the pressure of the high-pressure refrigerant that has flowed out of the internal heat exchanger 7 out of the refrigerant on the downstream side of the water-refrigerant heat exchanger 2 until it becomes a low-pressure refrigerant.

  Other configurations and operations are the same as those in the first embodiment. Therefore, even if the refrigeration cycle apparatus 10a is configured as in the present embodiment, the heating capacity or COP improvement effect and the manufacturing cost reduction effect can be obtained exactly as in the first embodiment.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  (1) In the above-described embodiment, an example in which an electric compressor that rotates and drives a scroll-type compression mechanism with an electric motor has been described as a compressor. However, the compressor is not limited to this.

  For example, as the compression mechanism, various types such as a vane compression mechanism and a rolling piston compression mechanism may be adopted as long as the compression mechanism is a displacement compression mechanism that compresses the refrigerant in the compression chamber by reducing the volume. it can. Further, the driving means for driving the compression mechanism is not limited to the electric motor, and for example, an internal combustion engine (engine) may be adopted.

  Moreover, in the above-mentioned embodiment, although the compressor 1 provided with one compression mechanism is employ | adopted, if an intermediate pressure refrigerant | coolant can be flowed in from the injection port 1b and it can be made to merge with the refrigerant | coolant of a compression process, for example, You may employ | adopt the compressor 1 which accommodated two compression mechanisms in one housing.

  Further, one compressor 1 may be configured by connecting two compressors in series. In this case, the suction port of the low stage compressor disposed on the low stage side becomes the suction port 1a of the compressor 1 as a whole, and the discharge port of the high stage compressor disposed on the high stage side is the compressor 1. The discharge port 1c as a whole is provided, and an injection 1b as a whole of the compressor 1 may be provided at a connection portion between the discharge port of the low-stage compressor and the suction port of the high-stage compressor.

  (2) In the above-described embodiment, the example in which it is determined whether or not the third refrigerant pressure P3 is lower than the high-pressure side refrigerant pressure Pd in step S3 of the flowchart in FIG. Instead of the pressure Pd, a target high pressure that is a target value of the high-pressure side refrigerant pressure Pd may be used.

  (3) In the above-described embodiment, the example in which the refrigeration cycle apparatuses 10 and 10a are applied to a heat pump type hot water heater has been described. However, the application of the refrigeration cycle apparatuses 10 and 10a is not limited thereto. For example, the present invention may be applied to an air conditioner and used to adjust the temperature of blown air that is blown into the air conditioning target space.

  (4) In the above-described embodiment, the example in which carbon dioxide is employed as the refrigerant of the refrigeration cycle has been described, but the refrigerant is not limited to this. For example, an HFC refrigerant (specifically, R134a), an HFO refrigerant (for example, R1234yf) or the like is used as the refrigerant, and the pressure of the high-pressure refrigerant discharged from the compressor 1 does not exceed the critical pressure of the refrigerant. A refrigeration cycle may be configured.

DESCRIPTION OF SYMBOLS 1 Compressor 1a Intake port 1b Injection port 1c Discharge port 2 Water-refrigerant heat exchanger (heat exchanger for heat dissipation)
3 Intermediate pressure expansion valve (intermediate pressure reducing means)
5 Low pressure expansion valve (Low pressure decompression means)
6 outdoor heat exchanger (heat exchanger for evaporation)

Claims (2)

A suction port (1a) that sucks low-pressure refrigerant into a compression chamber that changes the volume and compresses the refrigerant, an injection port (1b) that merges intermediate-pressure refrigerant with refrigerant in the compression process in the compression chamber, and the compression chamber A compressor (1) having a discharge port (1c) for discharging the compressed high-pressure refrigerant;
A heat dissipation heat exchanger (2) for radiating heat from the refrigerant discharged from the discharge port (1c);
Intermediate pressure reducing means (3) for reducing the pressure of the downstream heat exchanger (2) until it becomes the intermediate pressure refrigerant;
Low-pressure decompression means (5) for decompressing the heat-dissipating heat exchanger (2) downstream of the refrigerant until it becomes the low-pressure refrigerant;
An evaporating heat exchanger (6) for evaporating the refrigerant depressurized by the low pressure depressurizing means (5) and causing the refrigerant to flow out to the suction port (1a) side;
Intermediate pressure control means for controlling the operation of the intermediate pressure reducing means (3),
The intermediate pressure control means is configured such that when the compression chamber communicates with the discharge port (1c), the refrigerant pressure in the intermediate pressure is reduced so that the refrigerant pressure in the compression chamber approaches a predetermined pressure. A refrigeration cycle apparatus that controls operation.   The refrigeration cycle apparatus according to claim 1, wherein the predetermined pressure is a high-pressure side refrigerant pressure (Pd) of a cycle from the discharge port (1c) to a refrigerant inlet of the intermediate pressure reducing means (3). .

Images