JPH09145189A - Refrigerating cycle and air conditioner provided with the refrigerating cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent operational efficiency not only in the cooling operation but also in the heating operation. SOLUTION: In a refrigerant circuit provided with a plurality of compressors 1, 2, the compressors 1, 2 are arranged in series or in parallel by switching a flow switching means 4. In the cooling operation, a plurality of compressors are connected in series to perform the multistage compression, and the temperature of the refiigerant can be dropped, and the compression efficiency is improved to obtain the excellent operational efficiency. In the heating operation, a plurality of compressors are connected in parallel, and one compressor compresses the refrigerant to the prescribed pressure to raise the temperature of the refrigerant. Thus, the operation of excellent efficiency can be obtained in the heating operation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a compressor, a condenser,
The present invention relates to a refrigeration cycle including a refrigerant circuit having a decompression device, an evaporator, and the like, and more particularly, to a refrigeration cycle including a plurality of compressors for compressing refrigerant in multiple stages and an air conditioner including the refrigeration cycle.

[0002]

2. Description of the Related Art Generally, during the refrigerating cycle, a refrigerant of -30
When evaporating at a low temperature of ℃ or less, the evaporation pressure becomes low, so that the compression ratio of the compressor relatively increases and the compression efficiency becomes small, and the coefficient of performance of this refrigeration cycle becomes low. Further, the temperature of the discharged gas after compression also becomes high, and the deterioration of the lubricating oil progresses. Therefore, when a low evaporation temperature is required, for example, two compressors are used to perform two-stage compression to suppress the compression ratio of each compressor to a small value and suppress a decrease in the coefficient of performance.

That is, if the compression is performed twice, the compression ratio in one compression becomes small to prevent the reduction of compression efficiency, and if the discharged gas after compression is cooled and compressed again at a lower stage. The discharge gas temperature after the second compression can be kept low.

As a conventional multi-stage refrigeration cycle of this type, a two-stage compression one-stage expansion type shown in FIGS.
A refrigeration cycle of two-stage expansion and two-stage expansion is known.

In the two-stage compression one-stage expansion type refrigeration cycle shown in FIG. 12, a compressor 11A, an oil separator 12A, an intercooler 13A, a high-stage compressor 14A, an oil separator 15A, a condenser 16A, a liquid receiver. 17A, intercooler 13A, pressure reducing valve 18
The refrigerant circulates in the order of A, the evaporator 19A, and the low-stage compressor 11A, and a part of the refrigerant from the liquid receiver 17A is introduced into the intercooler 13A via the intercooling pressure reducing valve 20A, and the intercooler Cool 13A.

The refrigerant state of the refrigerating cycle in FIG. 12 is shown by a broken line in the Ph diagram shown in FIG. Each point 1f on the refrigeration cycle shown in FIG.
Similarly, if the Ph diagram corresponding to 8f, 1f-8
This is indicated by the symbol f.

Further, in the two-stage compression two-stage expansion type refrigeration cycle shown in FIG. 13, a compressor 11A, an oil separator 12A, an intercooler 13B, a high-stage compressor 14A, an oil separator 15A,
The condenser 16A, the liquid receiver 17A, the first pressure reducing valve 20B, the intercooler 13B, the pressure reducing valve 18A, the evaporator 19A, and the low-stage compressor 11A are circulated in this order, and the refrigerant from the liquid receiver 17A is reduced by the pressure reducing valve 20B. Is introduced into the intercooler 13B via.

The refrigerant state of the refrigeration cycle in FIG. 13 is shown by a broken line in the Ph diagram (Carnot cycle) shown in FIG. Similarly, 1f is similarly applied to the points corresponding to the respective points 1f to 8f on the refrigeration cycle shown in FIG.
It shows with the code of-8f.

In such a conventional two-stage compression type refrigeration cycle, at the time of cooling operation, the point 4f on the broken line in FIGS.
As compared with the case of compressing with one compressor as shown in (4FF), the refrigerating effect in the evaporator can be increased while lowering the gas temperature.

[0010]

However, as shown in FIG.
And as is apparent from the cycle shown by the broken line in FIG.
When the heat exchanger acts as a condenser, the enthalpy (h) is limited to the range of 4f to 5f or 7f shown in the figure and cannot be large, so that high heating efficiency cannot be obtained. That is, in the conventional two-stage compression type refrigeration cycle, when operating the use side heat exchanger as an evaporator, high operation efficiency can be obtained, but during the heating operation, the flow of the refrigerant is changed to change the use side heat exchanger. There is a problem that high operating efficiency cannot be obtained when the condenser is used as a condenser.

Therefore, the two-stage compression type refrigeration cycle is
It is used only for freezing operation, and it is not used for cooling and heating operation by reversible operation.

That is, in the conventional two-stage compression type refrigeration cycle, high operating efficiency can be obtained when the heat exchanger on the use side acts as an evaporator, but the flow of the refrigerant is changed as it is and the heat on the use side is changed. When the exchanger is used as a condenser, high operating efficiency cannot be obtained.

The present invention has been made to solve the above-mentioned problems, and is a multistage compression type refrigeration cycle capable of obtaining high operation efficiency not only in the refrigeration operation but also in the heating operation, and an air conditioner equipped with the refrigeration cycle. The purpose is to provide a machine.

[0014]

According to a first aspect of the present invention, a refrigerant is provided in a refrigerant circuit having a plurality of compressors, flow path switching means, a heat source side heat exchanger, a pressure reducing device and a utilization side heat exchanger. In the refrigerating cycle configured to circulate, the flow path switching means connects the plurality of compressors in series during the cooling operation in which the utilization-side heat exchanger acts as an evaporator to connect the plurality of compressors. , A heat source side heat exchanger, a pressure reducing device, a utilization side heat exchanger to form a circuit that circulates the refrigerant in this order, and the utilization side heat exchanger acts as a condenser During a heating operation, the plurality of compressors are connected in parallel. To form a circuit for circulating the refrigerant in the order of a plurality of compressors, a use side heat exchanger, a pressure reducing device, and a heat source side heat exchanger.

According to the first aspect of the invention, during the cooling operation, the flow path switching means is switched to connect a plurality of compressors in series to perform multi-stage compression. Therefore, in the cooling operation, when the use side heat exchanger acts as an evaporator, the refrigerant temperature can be lowered and the compression efficiency can be increased, so that high operation efficiency can be obtained.

On the other hand, during the heating operation, the flow path switching means is switched to connect a plurality of compressors in parallel to perform compression. Therefore, in the heating operation, the refrigerant is compressed by one compressor to a predetermined pressure. For this reason, when the utilization side heat exchanger acts as a condenser, the refrigerant temperature can be increased as opposed to the cooling operation, and highly efficient operation can be obtained.

In the present specification, the term "plurality of compressors" means that a plurality of individual compressors are arranged and one compressor has a plurality of compression parts, for example, a twin rotor type. It also includes each compression unit in the compressor.

The invention according to claim 2 is a plurality of compressors,
In a refrigeration cycle configured to circulate in a refrigerant circuit having a flow path switching means, a heat source side heat exchanger, a pressure reducing device, a use side heat exchanger, and an intercooler, the flow path switching means is a use side heat exchanger. During the cooling operation in which the compressor acts as an evaporator, the plurality of compressors are connected in series and the refrigerant is circulated in the order of the plurality of compressors, the heat source side heat exchanger, the pressure reducing device, and the use side heat exchanger. In the heating operation of forming a circuit to operate the heat exchanger on the use side as a condenser, the plurality of compressors are connected in parallel to each other, the plurality of compressors, the heat exchanger on the use side, the pressure reducing device, and the heat on the heat source side. A circuit that circulates the refrigerant in the order of the exchanger is formed, and the intermediate cooler uses a part of the refrigerant condensed in the refrigerant circuit when the refrigeration cycle is performing a cooling operation to compress the refrigerant circuit. Cool the refrigerant flowing between machines.

According to the invention described in claim 2, in the invention described in claim 1, the intercooler is arranged in the connecting pipe between the compressor during the cooling operation, and the refrigerant during the cooling operation. A part of the refrigerant condensed in the circuit is introduced into this intercooler to be cooled. As a result, the compression efficiency of the multi-stage compressor when the compressors are arranged in series during the cooling operation can be improved.

The invention described in claim 3 is a plurality of compressors,
In a refrigeration cycle configured to circulate in a refrigerant circuit having a flow path switching means, a heat source side heat exchanger, a pressure reducing device, a use side heat exchanger, and an intercooler, the flow path switching means is a use side heat exchanger. During the cooling operation in which the compressor acts as an evaporator, the plurality of compressors are connected in series and the refrigerant is circulated in the order of the plurality of compressors, the heat source side heat exchanger, the pressure reducing device, and the use side heat exchanger. In the heating operation of forming a circuit to operate the heat exchanger on the use side as a condenser, the plurality of compressors are connected in parallel to each other, the plurality of compressors, the heat exchanger on the use side, the pressure reducing device, and the heat on the heat source side. A circuit that circulates the refrigerant in the order of the exchanger is formed, and the intercooler is a part of the refrigerant condensed in the refrigerant circuit when the refrigeration cycle is performing a cooling operation between the compressors in the refrigerant circuit. Is mixed with the flowing refrigerant.

According to the invention described in claim 3, similarly to the invention described in claim 2, the intercooler is arranged in the connecting pipe between the compressors, and the refrigerant is used during the cooling operation. A part of the refrigerant condensed in the circuit is introduced into this intercooler to be cooled, but since the condensed refrigerant is introduced directly into the refrigerant flowing between the compressors, the refrigerant flowing between the compressors is efficiently cooled. can do.

The invention described in claim 4 is the first to third aspects of the present invention.
In the refrigeration cycle according to any one of the above, the heat source side heat exchanger is arranged outdoors to exchange heat with outdoor air,
The usage-side heat exchanger is arranged indoors and exchanges heat with indoor air.

According to the fourth aspect of the present invention, by using the above refrigeration cycle for the refrigeration cycle of the air conditioner, efficient operation can be achieved in the heating operation and the cooling operation.

[0024]

Embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a general household air conditioner. This type of air conditioner is composed of a use side unit A arranged indoors and a heat source side unit B arranged outdoors, both of which are connected by a refrigerant pipe 300.

2 and 3 are refrigerant circuit diagrams showing a refrigerant circuit (refrigeration cycle) of the air conditioner shown in FIG. 1. FIG. 2 is a refrigerant circuit during cooling operation (cooling operation), and FIG. 3 is heating. It shows the refrigerant circuit during operation (heating operation), and the refrigerant circulates as indicated by solid arrows in each.

The refrigerant circuit shown in FIGS. 2 and 3 has a first
A compressor (compression unit) 1, a second compressor (compression unit) 2, a flow path switching unit 4, an indoor heat exchanger 5, a capillary tube 6 as a pressure reducing device, and an outdoor heat exchanger 7 are provided. Also,
An on-off valve 8 is connected between the capillary tube 6 and the outdoor heat exchanger 7, and a refrigerant is introduced into the second compressor 2 by an intermediate heat exchanger (intermediate cooler) 10 via the capillary tube 9. Is configured to cool.

During the cooling operation, the flow path switching means 4 is switched as shown in FIG. 2, and the refrigerant discharged from the first compressor 1 is the intermediate heat exchanger 10, the second compressor 2, and the outdoor. The heat exchanger 7, the capillary tube 6, the indoor heat exchanger 5, and the first compressor 1 are circulated in this order. That is, the first compressor 1 and the second compressor 2 are connected in series.

On the other hand, during the heating operation, as shown in FIG. 3, the switching means 4 is switched and the refrigerant discharged from each of the first compressor 1 and the second compressor 2 is the indoor heat exchanger 5 and the capillary. Passing through the tube 6 and the outdoor heat exchanger 7,
It is divided into two by the flow path switching means 4, and each is divided into the first
The compressor 1 and the second compressor 2 flow in parallel and circulate. That is, the first compressor 1 and the second compressor 2 are connected in parallel.

The refrigeration circuit according to this embodiment includes two compressors, a first compressor 1 and a second compressor 2, and is configured to compress the refrigerant in multiple stages during the cooling operation.
In this way, when multi-stage compression is performed during the cooling operation, the compression efficiency is high and the coefficient of performance can be increased.

On the other hand, during the heating operation, the first compressor 1 and the second compressor 2 are connected in parallel,
High operation efficiency can be obtained even when the indoor heat exchanger (use side heat exchanger) 5 is used as a condenser.

Incidentally, these first compressor 1 and second compressor 2
However, in the present embodiment, a twin rotor type compressor 3 having two compressors is used, and one compressor 3 is two compressors. It also serves as a machine. By using such a twin rotor compressor 3, the configuration can be simplified and the refrigeration cycle can be downsized.

In the present specification, the term "compressor" means, when one compressor has a plurality of compression sections in addition to one compression section, that compression section as well.

In the twin rotor type compressor 3, as shown in FIG. 4, an electric motor unit (brushless DC motor) 103 is provided inside the closed casing 101, and the electric motor unit 103 rotates below. A first compressor 1 and a second compressor 2 that are driven to compress the refrigerant are provided on the rotary shaft of the electric shaft. The airtight container 101 is preliminarily divided into two, and the electric motor unit 103, the first compressor 1 and the second compressor 2 are housed therein, and then sealed by high frequency welding or the like.

The electric motor section 103 is composed of a stator 104 fixed to the inner wall of the closed casing 101, and a rotor 106 rotatably supported inside the stator 104 about a rotation shaft 105. There is. And the stator 104
Has a stator winding 107 that applies a rotating magnetic field to the rotor 106.

The first compressor 1 and the second compressor 2 are partitioned by an intermediate partition plate 108, and each of the first compressor 1
Has a first rotary cylinder 109 and a second rotary cylinder 110. The first rotary cylinder 109 and the second rotary cylinder 110 are provided with eccentric parts 111 and 112 that are driven to rotate by the rotary shaft 6, and these eccentric parts 111 and 112 are attached.
The eccentric positions are 180 degrees out of phase with each other.

First rotary cylinder 109 and second rotary cylinder 109
The rotary cylinder 110 is provided with a first roller 113 and a second roller 114 that rotate in the respective cylinders, and rotate inside the cylinder by rotation of the eccentric portions 111 and 112, respectively. Reference numerals 115 and 116 denote a first frame body and a second frame body, respectively, and the first frame body 115 is the partition plate 1.
08, a closed compression space of the cylinder 109 is formed, and the second frame 116 similarly forms a closed compression space of the cylinder 110 with the partition plate 8. Also, the first
The frame body 115 and the second frame body 116 respectively include bearing portions 117 and 118 that rotatably support the lower portion of the rotary shaft 106.

119 and 120 are discharge mufflers,
The first frame body 115 and the second frame body 116 are attached so as to cover them, respectively. The first rotary cylinder 1
09 and the discharge muffler 119 are communicated with each other through a discharge hole (not shown) provided in the first frame 115, and the second rotary cylinder 110 and the discharge muffler 120 are also connected to the second frame 1.
The discharge holes (not shown) provided in 16 communicate with each other.

Next, each connection port through which the refrigerant flows will be described.

The connection port E is the first rotary cylinder 10
9 is a refrigerant suction pipe, and the connection port B is a suction pipe connected to the second rotary cylinder 110.

The connection port F provided on the closed container is the first
A connection pipe C which is a discharge pipe for discharging the refrigerant compressed by the rotary cylinder 109 and is provided below the closed container.
Is a discharge pipe for discharging the refrigerant compressed in the second rotary cylinder 110.

With such a structure of the compressor 3, the refrigerant sucked from the connection port (suction port) E is compressed by the first rotary cylinder 109 in the first compressor 1, and the connection port (discharge port) F. Is discharged from. On the other hand, connection port (suction port)
The refrigerant sucked from B is compressed in the second rotary cylinder 110 in the second compressor 2 and is connected to the connection port (discharge port).
It is discharged from C.

As shown in FIG. 2, the flow path switching means 4 switches the flow paths to switch the flow of the refrigerant during the cooling / heating operation. The flow path switching means 4 uses a 6-way valve in the present embodiment, but may use an 8-way valve, or may use a 3-way valve or a 2-way valve in combination. . In the flow path switching means 4, the connection port A,
The six connection ports B, C, D, E, F, and G can be switched so as to form a combination described below.

The connection port A is a connection port on the inflow side of the indoor heat exchanger 5 during the cooling operation, the connection port B is a connection port on the inflow side of the first compressor 1 during the cooling operation, and the connection port C is The discharge side connection port of the first compressor 1, the connection port D is the inflow side connection port of the outdoor heat exchanger 7 during the cooling operation, and the connection port E is the inflow side connection port of the second compressor 2. F is the second compressor 2
Is the connection port on the discharge side.

Next, the refrigerant will be described.

In the present embodiment, either a single refrigerant or a mixed refrigerant can be used.
R-410A and R-410B are used. R-410
A is a two-component mixed refrigerant, which contains R-32 at 50 Wt
%, R-125 is composed of 50 wt%, and the boiling point is -5.
The temperature is 2.2 ° C and the dew point is -52.2 ° C. R-410B
Has a composition of 45 wt% for R-32 and 55 wt% for R-125.

In such a two-component mixed refrigerant, R-22
When compared with the conventional single refrigerant of No. 6, the discharge temperature of the compressor is 66.0 ° C. at R-22 under predetermined conditions.
On the other hand, R-410A has a temperature of 73.6 ° C., and R-22 has a condensation pressure of 17.35 bar, whereas
At 410A, it is 27.30 bar, and the evaporation pressure is R-
22 is 6.79 bar, while R-410A
Has a characteristic of 10.86 bar, and the entire refrigerant circuit has a higher temperature and a higher pressure than in the case where the conventional single refrigerant of R-22 is used. Therefore, when the mixed refrigerant is used, the refrigerant temperature is likely to be particularly high. Therefore, the compression efficiency can be increased and the coefficient of performance can be increased during the cooling operation by performing the two-stage compression.

When a mixed refrigerant such as R-410A and R-410B is used, since the boiling points of the refrigerants of the respective components are close to each other, the refrigerant composition is unlikely to change, and the refrigerant composition changes. There is no need to consider the problems such as temperature glide that occur. Therefore, control during driving becomes easy.

FIG. 5 is a control circuit diagram of the air conditioner.
The boundary between the dashed lines in the center of FIG. 5 shows the control circuit of the use side unit A on the left side, and the control circuit of the heat source side unit B on the right side. Both control circuits have power line 10
0 and the control line 200.

The user side unit A includes a rectifying circuit 11 and
A power supply circuit 12 for the motor, a power supply circuit 13 for the control, a motor drive circuit 15, a switch board 17,
The receiving circuit 18a, the display board 18, and the flap motor 1
9 and 9 are provided.

The rectifier circuit 11 rectifies 100V AC power supplied through the plug 10a and supplies DC power to the respective power supply circuits 12 and 13. The motor power supply circuit 12 adjusts the DC voltage supplied to the DC fan motor 16 to a voltage of 10 to 36V. This power supply circuit 1
Reference numeral 2 is a heat exchanger on the use side by a fan driven by the DC fan motor 16 by changing the rotation speed of the DC fan motor 16 by varying the DC voltage in the range of 10 to 36 V according to the signal sent from the microcomputer 14. This is for controlling the amount of conditioned air conditioned in 7 to be blown into the conditioned room.

The power supply circuit 13 for control generates a DC voltage of 5V to be supplied to the microcomputer 14. The motor drive circuit 15 responds to a signal from the microcomputer 14 based on the rotational position information of the DC fan motor 16 to control the timing of switching the energization to the stator winding of the DC fan motor 16. Switch board 17
Is fixed to the operation panel of the use side unit A, and the switch board 17 is provided with an on / off switch, a trial run switch, and the like. The state of these switches is captured by the microcomputer 14 by key scanning.
The receiving circuit 18a is the wireless remote controller 6
The remote control signal from 0 (for example, ON / OFF signal, cooling / heating switching signal, room temperature setting signal, etc.) is received, demodulated, and transferred to the microcomputer 14.
The display board 18 dynamically lights an LED based on a signal from the microcomputer 14 to display an operating state of the air conditioner. The flap motor 19 functions to move the flap that is conditioned in the utilization side heat exchanger 7 and changes the blowing direction of the conditioned air blown by the fan.

Further, in this control circuit, a room temperature sensor 20 for measuring the room temperature, a heat exchanger temperature sensor 21 for measuring the temperature of the utilization side heat exchanger 7, and a room humidity are measured. Humidity sensor 22 of The measured values detected by these sensors are A / D converted by the microcomputer 14 and taken in. The microcomputer 14 calculates based on these input information (acquisition information), and sends a signal for determining the operating capacity of the four-way switching valve and the compressor 1 to the heat source side unit B through the serial circuit 23 and the terminal board T3. send. Also, Triac 26
The heater relay 27 and the heater relay 27 are controlled by the microcomputer 14 through the driver 24. Thereby, the electric power supplied to the reheating heater 25 used in the dehumidifying operation (state of the refrigerating cycle used during the cooling operation) is controlled stepwise.

Reference numeral 30 is an external ROM that stores specific data indicating the type and characteristics of the air conditioner. These specific data are taken out from the external ROM immediately after the plug 14a is connected to the outlet and power is supplied to start up the microcomputer 14. The microcomputer 14 does not input a command from the wireless remote controller 60 or detect the state of an ON / OFF switch or a trial run switch (operation will be described later) until the specific data is taken out from the external ROM 30.

Next, the control circuit of the heat source side unit B will be described.

In the heat source side unit B, the terminal board T'1
, T'2, T'3 are respectively connected to terminal plates T1, T2, T3 arranged in the use side unit A. Reference numeral 31 is a varistor connected in parallel to the terminal plates T'1 and T'2, 32 is a noise filter, 34 is a reactor, 35 is a voltage doubler rectifier circuit, and 36 is a noise filter.

Reference numeral 39 is a serial circuit for dispersing the control signal supplied from the user side unit A from the power line through the terminal board T'3, and the dispersed signal is transmitted to the microcomputer 41. Reference numeral 40 is a current detector, which detects the current supplied to the heat source side unit B by current transformation (CT) and converts it into a signal for the microcomputer 41. 42 is a constant current circuit for generating electric power for operating the microcomputer 41, 43 is a motor section for operating the compressor 3 of the refrigeration cycle, 44
Is a discharge side temperature sensor that detects the temperature of the refrigerant discharged from the compressor 3. Reference numeral 45 is a fan motor, the speed of which is controlled in three stages and is arranged so that air can be sent to the heat source side heat exchanger. Further, in the heat source side unit B, an outdoor temperature sensor 48 for detecting the outdoor temperature is mounted near the air intake of the fan motor 45, and a heat exchanger temperature sensor 49 for detecting the temperature of the heat source side heat exchanger is provided on the heat source side. Installed in heat exchanger. These temperature sensors 4
The detection values obtained by 8 and 49 are A / D converted by the microcomputer 41 and taken in.

Reference numeral 50 is an external ROM of the user side unit A.
It is an external ROM having the same function as 30. The specific data of the heat source side unit B is the same as that described for the external ROM 30, but is stored in the ROM 50.

The symbol F in each control circuit of the heat source side unit B and the use side unit A is a fuse.

Each of the microcomputers (control devices) 14 and 41 is a ROM that stores a program in advance,
A RAM that stores reference data and a CPU that calculates a program are stored in the same container (87C196MC (MC sold by Intel Corporation).
S-96 series) and the like can be used).

On the other hand, when the microcomputer 41 receives the operation control signal for the cooling operation or the heating operation in the present embodiment, the flow path switching means 4 responds to each operation.
Switch the 6-way valve to two positions. Then, in the case of the cooling operation, as shown in FIG. 2, the connection port A and the connection port B, the connection port C and the connection port E, and the connection port D and the connection port F are connected. In the heating operation, as shown in FIG. 3, the connection port A and the connection port C, the connection port D and the connection port B, the connection port D and the connection port F, and the connection port A and the connection port G are connected.

Next, the operation of this embodiment will be described.

During the cooling operation, the flow path switching means 4 is located at a predetermined position and connects the respective connection ports A to E as shown in FIG. That is, the 6-way valve, which is the flow path switching means 4, connects the connection ports A and B, the connection ports C and E, the connection ports D and F.

The refrigerant discharged from the first compressor 1 is, as indicated by the arrow in FIG. 2, the first compressor 1, the intermediate heat exchanger 10, the second compressor 2, the outdoor heat exchanger. 7, the capillary tube 6, the indoor heat exchanger 5, and the first compressor 1 are circulated in this order. In this refrigerant circuit, the first compressor 1 and the second compressor 1
The compressor 2 is connected in series, and the first compressor 1 performs, for example, 2.5 volume ratio compression, and the second compressor 2 performs 1.5 volume ratio compression. By thus performing the two-stage compression, it is possible to improve the compression efficiency and prevent the discharge gas from having a high temperature. During the cooling operation, the outdoor heat exchanger 7 is
Acting as a condenser, the indoor heat exchanger 5 functions as an evaporator.

On the other hand, a part of the refrigerant condensed in the outdoor heat exchanger 7 passes through the bypass circuit flowing through the opening / closing valve 8 and evaporates in the intermediate heat exchanger 10 via the capillary tube 9, and the second compressor 2 Returned to. In the intermediate heat exchanger 10, the refrigerant flowing from the first compressor 1 to the second compressor 2 is cooled to lower the temperature of the refrigerant, and the refrigerant discharged from the second compressor 2 is prevented from reaching a high temperature. .

The refrigerant used for cooling in the intercooler 10 is returned to the space between the first compressor and the second compressor without being used (still evaporated) to mix the refrigerant. It may directly contribute to cooling. In this case,
Furthermore, if the decompressed refrigerant is returned directly to the refrigerant between the first compressor and the second compressor and mixed without using the intermediate heat exchanger 10, the refrigerant can be cooled directly, and further effect is obtained. The cooling effect can be obtained.

FIG. 1 shows a Ph diagram during this cooling operation.
The solid line is shown at 0. In FIG. 10, the above-mentioned conventional technique is shown by a broken line, and is compared with that of the present embodiment. In the Ph diagram of FIG. 10, reference numerals 1F, 2F, 3F, 4F, 5F, 6F, 7F,
8F corresponds to the reference numerals of the measurement points of the refrigerant circuit shown in FIG. 2, respectively. That is, 1F, 2F, 3F, 4 of FIG.
F represents the two-stage compression by the compressor 1 and the compressor 2, 4F and 5F are the inlet and the outlet of the outdoor heat exchanger which acts as a condenser, and between the 7F and 8F, the capillary tubes 6 and 8F. Between 1 and 1F are an inlet and an outlet of the indoor heat exchanger 5 which functions as an evaporator.

As is apparent from FIG. 10, during the cooling operation, the refrigerant is compressed by the compressor 1 and the compressor 2 arranged in series, so that the compression ratio of the refrigerant is increased directly by one compressor ( 4FF), the temperature of the discharge gas can be lowered. Moreover, since it is compressed by the two compressors 1 and 2, the compression efficiency is excellent.

In particular, a mixed refrigerant is used as the refrigerant,
When the temperature of the refrigerant in the refrigerant circuit is likely to rise, the two-stage compression as in the present embodiment can be adopted to prevent the refrigerant from having an abnormally high temperature.

During the heating operation, as shown in FIG. 3, the flow path switching means 4 is located at a predetermined position and connects the connection ports A to E. That is, the flow path switching means 4 connects the connection port A and the connection port C, the connection port A and the connection port F, the connection port B and the connection port D, the connection port E and the connection port D. Thereby, in the refrigerant circuit, the first compressor 1 and the second compressor 2 are connected in parallel.

The refrigerant discharged from the first compressor 1 and the second compressor 2 is, as shown by the arrow in FIG. 3, the indoor heat exchanger 5 acting as a condenser, the capillary tube 6, and the outdoor. The heat exchanger 7, the connection port D and the connection port B are divided into two parts, divided into the first compressor 1 and the second compressor 2 and introduced into each. The on-off valve 8 that introduces the refrigerant into the intermediate heat exchanger 10 is closed.

In this case, in the indoor heat exchanger 5 acting as a condenser, the refrigerant is not two-stage compressed but each compressor compresses it to a predetermined pressure. Therefore, the refrigerant temperature in the condenser can be increased, and the heat exchange efficiency in the condenser can be increased. That is, as shown in FIG. 10, in the compression process, as shown by the broken line, enthalpy can be taken from 4FF to 7F at the inlet of the condenser during heating operation, so that heat exchange efficiency can be improved.

Therefore, in the air conditioner according to this embodiment, high operating efficiency can be obtained not only during the cooling operation (cooling operation) but also during the heating operation (heating operation).

Next, the second and third embodiments of the present invention will be described with reference to FIGS.

In the embodiment described below, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the second embodiment shown in FIGS. 6 and 7,
This is different from the first embodiment in that the intercooler and the circuit for returning a part of the refrigerant in the refrigerant circuit to the intercooler in the above-described embodiment are not provided. Further, the outdoor heat exchanger 2 is divided into two parts, and the flow path switching means 4 is configured to connect the eight connection ports A to H so as to pass through these two divided heat exchangers. ing.

During the cooling operation, the flow path switching means 4
Is located at a predetermined position, and as shown in FIG.
Connect ~ H. That is, the 8-way valve that is the flow path switching unit 4 connects the connection ports A and B, the connection ports C and D, the connection ports E and G, the connection ports F, and the connection ports H.

Therefore, during the cooling operation, the refrigerant discharged from the first compressor 1 is the first refrigerant as shown by the arrow in FIG.
Compressor 1, part 7B of outdoor heat exchanger 7, intercooler 1
0, the second compressor 2, the other part 7A of the outdoor heat exchanger 7, the capillary tube 6, the indoor heat exchanger 5, and the first compressor 1 are circulated in this order. In this refrigerant circuit, the first compressor 1 and the second compressor 1
The compressor 2 is connected in series, and the first compressor 1 has a volume ratio of 2. in the same manner as in the above-described first embodiment.
It is compressed to 5 and further compressed by the second compressor 2 by a volume ratio of 1.5. By thus performing the two-stage compression, it is possible to improve the compression efficiency and prevent the discharge gas from having a high temperature. In the cooling operation, the outdoor heat exchanger 7 acts as a condenser and the indoor heat exchanger 5 functions as an evaporator.

Also in the second embodiment, as in the above-described first embodiment, during the cooling operation, the refrigerant is compressed in two stages by the compressor 1 and the compressor 2 arranged in series, so that the compression efficiency is improved. It is possible to improve the temperature and prevent the discharge gas from increasing in temperature.

During the heating operation, the flow path switching means 4 is switched to connect the respective connection ports A to H as shown in FIG.
That is, the 8-way valve which is the flow path switching means 4 includes the connection ports A and C, the connection ports A and F, the connection ports B and D, the connection ports E and H, the connection ports H and The connection port G is connected. Then, the connection port A is connected so as to join from two places of the connection ports C and F, and the connection port H is connected so as to be branched to the connection port E and the connection port G.

During the heating operation in the second embodiment, the refrigerant discharged from each of the first compressor 1 and the second compressor 2 passes through the connection ports C and F, respectively, and the connection port A.
, The indoor heat exchanger 5, which acts as a condenser, the capillary tube 6, a part 7A of the outdoor heat exchanger 7, is bisected by the connection port H, and is flowed to the connection ports E and G,
It is introduced into the second compressor 2 from the connection port E. On the other hand, from the connection port G, after passing through the remaining portion 7B of the outdoor heat exchanger 7, it is introduced into the first compressor 1 via the connection port D and the connection port B.

During the heating operation in the second embodiment, the refrigerant is not the two-stage compression but the compressors 1 and 2 act in parallel, and each compressor compresses the refrigerant to a predetermined pressure. Therefore, the refrigerant temperature in the indoor heat exchanger 5 acting as a condenser can be increased, and the heat exchange efficiency in the condenser can be increased. That is, also in the second embodiment, as shown in FIG. 10, the enthalpy from 4FF to 7F can be taken at the inlet of the condenser in the compression step as shown by the broken line, so that the heat exchange efficiency is improved. Can be made.

Therefore, also in the air conditioner according to the second embodiment, high operating efficiency can be obtained not only during the cooling operation (cooling operation) but also during the heating operation (heating operation).

Next, a third embodiment will be described.

In the third embodiment shown in FIGS. 8 and 9,
It differs from the first embodiment described above in that the flow path switching means 4 is configured by a combination of a four-way switching valve 4a and open / close valves 4b, 4c.

During the cooling operation, the four-way switching valve 4a
As shown in FIG. 8, the connection ports A and B, the connection ports C and D are connected, and the on-off valves 4b and 4c are closed.

As a result, during the cooling operation, the first compressor 1
The refrigerant discharged from the outside passes through the first compressor 1, the intercooler 10, the second compressor 2, the connection port D and the connection port C of the four-way switching valve 4a, as shown by the arrow in FIG. The heat exchanger 7, the capillary tube 6, the indoor heat exchanger 5, and the first compressor 1 are circulated in this order. On the other hand, a part of the refrigerant condensed in the outdoor heat exchanger 7 passes through the bypass circuit flowing through the opening / closing valve 8, passes through the intercooler 10 via the capillary tube 9, and is returned to the second compressor 2. This intercooler 10
Then, the refrigerant flowing from the first compressor 1 to the second compressor 2 is cooled to lower the temperature of the refrigerant and prevent it from becoming a high temperature.

The Ph diagram during the cooling operation is shown by the solid line in FIG. 10 as in the first embodiment.

That is, in this refrigerant circuit, the first compressor 1 and the second compressor 2 are connected in series, and the first compressor 1 is similar to the above-described first embodiment. For example, the volume ratio is compressed by 2.5, and the second compressor 2 is compressed by volume ratio of 1.5. By compressing in two stages like this,
It is possible to improve the compression efficiency and prevent the discharge gas from increasing in temperature.

In the third embodiment, as in the first embodiment, the refrigerant is compressed in two stages by the first compressor 1 and the second compressor 2 arranged in series during the cooling operation. As a result, the compression efficiency can be improved and the temperature of the discharged gas can be prevented from rising, and the refrigerant circuit can be easily constructed by combining the generally used four-way switching valve 4a and the on-off valves 4b and 4c.

During heating operation, as shown in FIG. 9, the four-way switching valve 4a is switched to connect the connection ports A, D and B.
And the connection port C are connected, the on-off valves 4b and 4c are opened, and the on-off valve 8 is closed.

During the heating operation in the third embodiment, the refrigerant discharged from the first compressor 1 passes through the on-off valve 4b and merges with the refrigerant discharged from the second compressor 2, and the connection ports D and Passing through the connection port A, the indoor heat exchanger 5 acting as a condenser, the capillary tube 6, and the outdoor heat exchanger 7,
It is returned to the first compressor 1 through the connection port C and the connection port B. On the other hand, before the first compressor 1, a part of the circulating refrigerant passes through the on-off valve 4c and is returned to the second compressor 2.

During the heating operation in the third embodiment, the refrigerant is not the two-stage compression but the compressors 1 and 2 act in parallel as in the above-described embodiment, and the respective compressors have the predetermined operation. It will be compressed to the pressure of. Therefore, the refrigerant temperature in the indoor heat exchanger 5 acting as a condenser can be increased, and the heat exchange efficiency in the condenser can be increased. That is, also in the third embodiment, as shown in FIG. 10, the enthalpy from 4FF to 7F can be taken at the inlet of the condenser in the compression step as shown by the broken line, so that the heat exchange efficiency is improved. Can be made.

Therefore, also in the air conditioner according to the third embodiment, high operating efficiency can be obtained not only during the cooling operation (cooling operation) but also during the heating operation (heating operation).

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, the flow path switching means has been described by taking the 8-way valve, the 6-way valve, the 4-way valve and the combination of these and the on-off valve (2-way valve) as an example in the above-mentioned embodiment. Not limited to the above, the same effect can be obtained even with a combination of only the on-off valve (two-way valve).

Further, in the above-mentioned embodiment, the air conditioner is used as an example for explanation, but the present invention is not limited to this, and any device having a refrigeration cycle may be used, for example, in a refrigerator or a vending machine. You can

[0098]

According to the invention described in claim 1, in the refrigerant circuit including a plurality of compressors, the compressors are arranged in series or in parallel by switching the flow path switching means. Therefore, during cooling operation, multiple compressors are connected in series to perform multi-stage compression, so that the refrigerant temperature can be lowered and the compression efficiency can be increased to obtain high operation efficiency. Since the compressors are connected in parallel, one compressor can compress the refrigerant to a predetermined pressure and raise the refrigerant temperature. Therefore, a highly efficient operation can be obtained during the heating operation.

According to the invention of claim 2, claim 1
In the invention described in (3), since the intercooler is arranged in the connecting pipe between the first compressor and the second compressor during the cooling operation, the first compressor in the multi-stage compressor when arranged in series. Since the refrigerant between the first compressor and the second compressor is cooled, it is possible to suppress the temperature rise of the refrigerant and improve the compression efficiency. Moreover, since the intercooler uses a part of the refrigerant condensed in the refrigeration cycle, it is not necessary to separately provide a cooling system.

According to the invention described in claim 3, similarly to the invention described in claim 2, the intercooler is arranged in the connecting pipe between the compressor and the refrigerant is used during the cooling operation. A part of the refrigerant condensed in the circuit is introduced into this intercooler to be cooled, but since the condensed refrigerant is introduced directly into the refrigerant flowing between the compressors, the refrigerant flowing between the compressors is efficiently cooled. can do.

According to the invention described in claim 4, by using the refrigeration cycle described above in the refrigeration cycle of the air conditioner, efficient operation can be achieved in the heating operation and the cooling operation.

[0102]

[Brief description of the drawings]

FIG. 1 is a perspective view of an air conditioner applied to an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram during a cooling operation of the air conditioner shown in FIG.

FIG. 3 is a refrigerant circuit diagram during heating operation in the air conditioner shown in FIG.

FIG. 4 is a sectional view of a compressor applied to an embodiment of the present invention.

5 is a control circuit diagram of the air conditioner shown in FIG. 1. FIG.

FIG. 6 is a refrigerant circuit diagram during a cooling operation according to the second embodiment.

FIG. 7 is a refrigerant circuit diagram during heating operation according to the second embodiment.

FIG. 8 is a refrigerant circuit diagram during a cooling operation according to a third embodiment.

FIG. 9 is a refrigerant circuit diagram during heating operation according to a third embodiment.

FIG. 10 P of a refrigeration cycle in two-stage compression and one-stage expansion
It is an H diagram.

FIG. 11 P of refrigeration cycle in two-stage compression and two-stage expansion
It is an H diagram.

FIG. 12 is a refrigerant circuit diagram during a cooling operation in a conventional refrigeration circuit.

FIG. 13 is a refrigerant circuit diagram in another conventional refrigeration circuit during a cooling operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor (compressing part) 2 Compressor (compressing part) 4, 4a, 4b, 4c Flow path switching means 5 Indoor heat exchanger (use side heat exchanger) 6 Capillary tube (pressure reducing device) 7 Outdoor heat exchanger ( Heat source side heat exchanger) 10 Intercooler

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yoshinori Toya, 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Inventor Masahiro Kobayashi, 2-5 Keihan Hondori, Moriguchi City, Osaka Prefecture No. 5 within Sanyo Electric Co., Ltd. (72) Inventor Takashi Kawanabe 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Within Sanyo Electric Co., Ltd. (72) Yoshitaka Hara, 2 Keihan Main Street, Moriguchi City, Osaka Prefecture 5-5, Sanyo Electric Co., Ltd.

Claims (4)

[Claims] 1. A refrigeration cycle configured to circulate a refrigerant in a refrigerant circuit having a plurality of compressors, flow path switching means, a heat source side heat exchanger, a pressure reducing device, and a use side heat exchanger, wherein: The switching means connects the plurality of compressors in series during the cooling operation in which the use side heat exchanger acts as an evaporator, and the plurality of compressors, the heat source side heat exchanger, the pressure reducing device, and the use side heat are connected. A circuit for circulating the refrigerant in the order of the exchanger is formed, and during the heating operation in which the use side heat exchanger acts as a condenser, the plurality of compressors are connected in parallel, and the plurality of compressors and the use side heat are connected. A refrigeration cycle characterized by forming a circuit for circulating a refrigerant in the order of an exchanger, a pressure reducing device, and a heat source side heat exchanger. 2. A refrigeration cycle configured to circulate in a refrigerant circuit having a plurality of compressors, flow path switching means, heat source side heat exchangers, pressure reducing devices, utilization side heat exchangers, and intercoolers, The flow path switching means connects the plurality of compressors in series during the cooling operation in which the heat exchanger on the use side acts as an evaporator to connect the plurality of compressors, the heat exchanger on the heat source side, the decompressor, A circuit for circulating the refrigerant in the order of the side heat exchanger is formed, and during the heating operation in which the use side heat exchanger acts as a condenser, the plurality of compressors are connected in parallel and the plurality of compressors, the use side. A circuit that circulates the refrigerant in the order of the heat exchanger, the pressure reducing device, and the heat source side heat exchanger is formed, and the intercooler is one of the refrigerant condensed in the refrigerant circuit during the cooling operation of the refrigeration cycle. Flow between the compressors in the refrigerant circuit. Refrigeration cycle, characterized by cooling the that coolant. 3. A refrigeration cycle configured to circulate in a refrigerant circuit having a plurality of compressors, flow path switching means, heat source side heat exchangers, pressure reducing devices, utilization side heat exchangers and intercoolers, The flow path switching means connects the plurality of compressors in series during the cooling operation in which the heat exchanger on the use side acts as an evaporator to connect the plurality of compressors, the heat exchanger on the heat source side, the decompressor, A circuit for circulating the refrigerant in the order of the side heat exchanger is formed, and during the heating operation in which the use side heat exchanger acts as a condenser, the plurality of compressors are connected in parallel and the plurality of compressors, the use side. A circuit that circulates the refrigerant in the order of the heat exchanger, the pressure reducing device, and the heat source side heat exchanger is formed, and the intercooler is one of the refrigerant condensed in the refrigerant circuit during the cooling operation of the refrigeration cycle. Parts are cooled between the compressors in the refrigerant circuit. Refrigeration cycle, characterized in that the mix to. 4. The refrigeration cycle according to any one of claims 1 to 3, wherein the heat source side heat exchanger is placed outdoors to exchange heat with outdoor air, and the use side heat exchanger is placed indoors. An air conditioner that is placed and exchanges heat with indoor air.