JPH085185A - Refrigerating cycle system - Google Patents

Abstract

PURPOSE:To provide a refrigerating cycle in which sufficient supercooling degree of refrigerant can be early obtained after a compressor is started without depending upon the distribution of refrigerant in a refrigerant circuit and excess refrigerant for obtaining sufficient supercooling degree of the refrigerant can be eliminated. CONSTITUTION:In this refrigerating cycle system, the refrigerant in a second refrigerant tube 24 fed from a heat source side heat exchanger 3 by the start of a compressor 1 is heat exchanged with the refrigerant in an accumulator 6 by a second heat exchanger 7, and additionally heat exchanged with low- temperature and low-pressure refrigerant fed from a second flow controller 9 in a first bypass circuit 8. Accordingly, the refrigerant from the accumulator 6 can be moved by the heat exchange with the refrigerant from the exchanger 3, and the superheat degree of the refrigerant in the tube 24 can be sufficiently obtained. On the other hand, even if there is no supercooling excess refrigerant in the accumulator 6, the refrigerant in the tube 24 is sufficiently supercooled by the heat exchange with the refrigerant of the circuit 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating cycle system applied to, for example, an air conditioner or a refrigerating device, and more particularly to a system capable of sufficiently securing a degree of supercooling of a refrigerant toward a heat exchanger on the use side. It is about.

[0002]

2. Description of the Related Art FIG. 14 is a refrigerant circuit diagram showing an example of a refrigerant cycle system used in a conventional air conditioner. In FIG. 14, 1 is a compressor, 2 is a four-way switching valve, 3
Is a heat source unit side heat exchanger, 4a and 4b are first flow rate control devices, 5a and 5b are utilization side heat exchangers, 6 is an accumulator, 7 is a heat source unit side heat exchanger 3 and the first flow rate control unit 4
It is a second heat exchanging section for exchanging heat in the accumulator 6 by passing a part of the second refrigerant pipe 24 connecting the a and 4b. The arrows in the figure indicate the direction in which the refrigerant flows during the cooling operation. In FIG. 14, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 radiates heat in the heat-source-unit-side heat exchanger 3 that functions as a condenser, and becomes a high-pressure liquid or a gas-liquid two-phase refrigerant close to the liquid. . Then the second
The refrigerant that has passed through the heat exchange section 7 is further cooled by exchanging heat with the low-pressure low-temperature liquid refrigerant in the accumulator 6 to become a supercooled refrigerant and flow toward the use-side heat exchangers 5a and 5b. There is.

FIG. 15 is a refrigerant circuit diagram showing another example of a refrigerant cycle system used in a conventional air conditioner,
The air conditioner shown in FIG. 14 has the same structure as that of the air conditioner shown in FIG. 14 except that the second heat exchange section 7 in FIG. 14 is not provided and the second flow control device 9 is provided. First bypass circuit 8 connecting 24 and the first refrigerant pipe 23
And the first bypass circuit 8 on the output side of the second flow rate control device 9
A first heat exchange section 10 for exchanging heat between the refrigerant inside and the refrigerant in the second refrigerant pipe 24 from the outlet side of the heat source side heat exchanger 3 to the connection section of the first bypass circuit 8; Is equipped with. In this air conditioner, a part of the refrigerant flowing toward the use side heat exchangers 5a and 5b is bypassed by the first bypass circuit 8 and the second flow rate control device 9 depressurizes the refrigerant, thereby reducing the low temperature and low temperature. Use as a phase refrigerant. Then, in the first heat exchange section 10, by cooling the refrigerant discharged from the heat source side heat exchanger 3, a large degree of supercooling of the refrigerant flowing toward the use side heat exchangers 5a and 5b is secured. Have a function. The refrigerant that has secured a sufficient degree of supercooling is decompressed as it is by the first flow rate control devices 4a and 4b, and after absorbing heat in the use side heat exchangers 5a and 5b that function as evaporators,
It returns to the compressor 1 again via the four-way switching valve 2 and the accumulator 6.

The reason why the supercooled refrigerant is used before the first flow rate control devices 4a and 4b is as follows. If there are a plurality of heat exchangers on the use side, the flow of the refrigerant toward each of them must be divided. At this time, if the refrigerant is in a gas-liquid two-phase state, depending on the direction and shape of the branch portion, it is not possible to divide the flow evenly due to the state difference between the liquid portion and the gas portion, and an appropriate amount of refrigerant for each use side heat exchanger. May stop flowing.
When the state of the refrigerant at the inlet of the first flow rate control device in front of the utilization side heat exchanger is a two-phase state, it is difficult to control the flow rate of the refrigerant, so the state of the refrigerant at the inlet is a single phase of liquid or gas. It is desirable to be in style. In practice, for example, in order to bring the refrigerant into a single-phase liquid state, the degree of supercooling becomes smaller due to the pressure drop due to the pressure drop in the pipe to the branch portion and the first flow rate control device and the height difference. It is necessary to secure a sufficient degree of supercooling of the refrigerant on the heat source machine side.

[0005]

In order to exchange heat with the liquid refrigerant in the accumulator 6 as in the refrigerant cycle system of FIG. 14, a certain amount of liquid refrigerant must be present in the accumulator 6 at all times. I have to. This is because the gas refrigerant in the accumulator 6 has a low-pressure saturation temperature or higher, while it is in a liquid state at a low-pressure saturation temperature or lower, so that the temperature difference from the high-temperature refrigerant discharged from the heat source side heat exchanger 3 is large. This is because the amount of heat exchange becomes large as much as possible. However, such liquid refrigerant is
The purpose is only to secure the degree of supercooling, and if it is excluded, it is merely a surplus refrigerant. Therefore, the amount of the refrigerant is increased in the entire refrigerant cycle system, and the cost is burdened.

On the other hand, in the case of the refrigerant cycle system of FIG. 15, since heat is not exchanged in the accumulator 6,
The surplus refrigerant as described above is almost unnecessary. However, when the compressor 1 is stopped, the refrigerant is distributed everywhere in the refrigerant circuit. For example, when a large amount of refrigerant mainly exists inside the heat source unit side heat exchanger 3 or in the first heat exchange unit 10, the first heat exchange unit 10 has already secured a sufficient degree of supercooling. Since the liquid refrigerant flows, the refrigerant flow rate can be smoothly controlled by controlling the second flow rate control device 9 when the compressor 1 is started.

However, the heat source unit side heat exchanger 3 and the first
When the compressor 1 is started in a state where a large amount of refrigerant is distributed in a place other than the heat exchange section 10, the liquid refrigerant is likely to accumulate in the accumulator 6, and the first heat exchange section 10 has a gas-liquid two-phase state. Refrigerant is present. When the refrigerant is in the gas-liquid two-phase state, the behavior of the refrigerant is unstable, and the second flow rate control device 9 cannot perform the flow rate control of the refrigerant well. Therefore, it becomes difficult to secure a sufficient degree of supercooling in the first heat exchange unit 10. Then, when the compressor 1 is operated at a low capacity by capacity control, or when the heat source temperature (outside air temperature) is low on the heat source machine side and the pressure on the high pressure side is low, the low pressure side is inevitable. Since the pressure also decreases, the refrigerant circulation amount by the compressor 1 does not increase, and the refrigerant in the accumulator 6 does not easily move. Therefore, as a result, it took a long time until the first heat exchange section 10 produces a liquid refrigerant having a sufficient degree of supercooling, that is, until it reaches a steady operation.

The present invention has been made in order to eliminate the disadvantages inherent in the above-mentioned prior art, and it is sufficient for the refrigerant after the compressor is started regardless of the distribution of the refrigerant in the refrigerant circuit. It is an object of the present invention to provide a refrigeration cycle system capable of ensuring a high degree of supercooling at an early stage and eliminating excess refrigerant for securing a sufficient degree of supercooling to the refrigerant.

[0009]

A refrigeration cycle system according to the present invention includes a compressor, a heat source side heat exchanger, a first flow rate control device, a utilization side heat exchanger, and an accumulator.
At least a first refrigerant pipe connecting the outlet side of the heat exchanger on the utilization side and the inlet side of the accumulator, and a second refrigerant pipe connecting the outlet side of the heat source side heat exchanger and the inlet side of the utilization side heat exchanger are provided. A first bypass circuit that has a main refrigerant circuit, a second flow rate control device and that connects the second refrigerant pipe and the first refrigerant pipe, and a first bypass circuit on the outlet side of the second flow rate control device. A first heat exchange section for exchanging heat between the refrigerant in the second heat exchanger and the refrigerant in the second refrigerant pipe from the heat source unit side heat exchanger outlet side to the connection section of the first bypass circuit; It is provided with a second heat exchanging section for exchanging heat between the refrigerant in the refrigerant pipe and the refrigerant in the accumulator.

Further, the compressor, the heat source side heat exchanger, the first flow rate control device, the utilization side heat exchanger, and the accumulator are provided, and the utilization side heat exchanger outlet side and the accumulator inlet side are connected. A second refrigerant pipe having at least a second refrigerant pipe connecting the heat source unit side heat exchanger outlet side and the utilization side heat exchanger inlet side of the second refrigerant pipe, and a second flow rate control device. A first bypass circuit connecting the refrigerant pipe and the first refrigerant pipe, the refrigerant in the first bypass circuit on the outlet side of the second flow rate control device, and the heat source unit side heat exchanger outlet side to the first bypass circuit. The heat exchange is performed between the refrigerant in the second refrigerant pipe and the refrigerant in the accumulator, and the first heat exchange portion that performs heat exchange with the refrigerant in the second refrigerant pipe up to the connection portion of the circuit. And a second heat exchanging part for performing the first heat exchanging part and the second heat exchanging part integrally. In which is disposed in the accumulator.

The first heat exchange section accommodates the first bypass circuit on the outlet side of the second flow rate control device in the second refrigerant pipe at a position corresponding to the second heat exchange section. It is composed.

Further, the compressor, the heat source side heat exchanger, the first flow rate control device, the utilization side heat exchanger, and the accumulator are provided, and the utilization side heat exchanger outlet side and the accumulator inlet side are connected. At least the second refrigerant pipe connecting the heat source unit side heat exchanger outlet side and the use side heat exchanger inlet side, and the third refrigerant pipe connecting the upper part in the accumulator and the compressor suction side. A main refrigerant circuit provided, an oil return circuit that connects the lower part of the accumulator and the third refrigerant pipe to return the lubricating oil containing the refrigerant of the accumulator to the compressor suction side, and the lubricating oil containing the refrigerant in the oil return circuit. And a third heat exchange section for exchanging heat with the refrigerant in the second refrigerant pipe.

In addition, a second bypass circuit for connecting the second refrigerant pipe and the first refrigerant pipe is provided.

Then, the second bypass circuit is provided with a third flow rate control device for adjusting the flow rate of the refrigerant flowing through the second bypass circuit.

The compressor, the heat source side heat exchanger, the first
Flow control device, use side heat exchanger, accumulator, first refrigerant pipe connecting the use side heat exchanger outlet side and the accumulator inlet side, heat source side heat exchanger outlet side and use side heat exchange A second refrigerant pipe connecting at least the inlet side, a main refrigerant circuit including at least a fourth refrigerant pipe connecting the compressor discharge side and the heat source side heat exchanger inlet side, and a second flow control device. Having a first refrigerant pipe and connecting the second refrigerant pipe and the first refrigerant pipe
Refrigerant in the first bypass circuit on the outlet side of the second flow rate control device and the refrigerant in the second refrigerant pipe from the outlet side of the heat source side heat exchanger to the connection part of the first bypass circuit A first heat exchange section for exchanging heat with the second heat exchanger, a fourth flow rate control device, a fourth refrigerant pipe, and a second heat exchanger from the heat source unit side heat exchanger outlet side to the first heat exchange section. Third connecting with the refrigerant pipe
And a fourth heat exchange section for exchanging heat between the refrigerant in the third bypass circuit and the refrigerant in the accumulator.

Furthermore, the temperature detecting means for detecting the temperature of the heat source medium which passes through the heat source side heat exchanger and exchanges heat with the refrigerant in the heat source side heat exchanger, and the temperature detecting means detect the temperature. A control means for controlling the flow rate of the refrigerant by the fourth flow rate control device is provided based on the temperature of the heat source medium.

[0017]

In the refrigeration cycle system according to the present invention, the refrigerant in the second refrigerant pipe flowing out from the heat source side heat exchanger exchanges heat with the refrigerant in the accumulator in the second heat exchange section, and Heat is exchanged with the low-temperature low-pressure refrigerant flowing through the first bypass circuit. Therefore, when the distribution of the refrigerant is biased to the accumulator immediately before the start of the compressor, the refrigerant in the accumulator is evaporated by heat exchange with the refrigerant from the heat source side heat exchanger to facilitate the movement from the accumulator. At the same time, a sufficient degree of supercooling of the refrigerant in the second refrigerant pipe is ensured. On the other hand, when a large amount of refrigerant is distributed to the heat source side heat exchanger or its outlet, even if there is no excess refrigerant for supercooling in the accumulator, heat exchange with the refrigerant in the first bypass circuit causes Ensure a sufficient degree of supercooling for the refrigerant in the refrigerant piping.

Further, the first heat exchange section and the second heat exchange section are integrally formed. Furthermore, the first of these integrated
The heat exchange section and the second heat exchange section are arranged so as to be able to conduct heat to, for example, the inside or the outside of the accumulator. Therefore,
Structurally simple.

The refrigerant flowing in the second refrigerant pipe at the position corresponding to the second heat exchange section is heat-exchanged with both the refrigerant of the first heat exchange section and the refrigerant of the second heat exchange section. By the replacement, the inside and outside of the second refrigerant pipe can be efficiently cooled. Therefore, the refrigerant flowing into the first flow rate control device reaches a sufficient degree of supercooling in a short time.

Further, a third refrigerant for exchanging heat between the refrigerant in the oil return circuit connected from the accumulator to the compressor suction side and the refrigerant in the second refrigerant pipe flowing out from the heat source side heat exchanger.
The heat exchanging part of (1) ensures a sufficient degree of supercooling of the refrigerant flowing into the first flow rate control device. At the same time, it also eliminates liquid back when returning oil to the suction side of the compressor.

Further, a part of the refrigerant flowing into the first flow rate control device returns to the accumulator through the second bypass circuit. Therefore, the refrigerant for evaporating in the third heat exchange unit collects in the accumulator.

The third flow rate control device provided in the second bypass circuit controls the flow rate of the refrigerant flowing through the second bypass circuit. Accordingly, the third flow rate control device appropriately adjusts the amount of refrigerant returned to the accumulator. Therefore, it is possible to prevent the compressor from being damaged due to returning more refrigerant than necessary to the accumulator.

The fourth heat exchange section exchanges a part of the high-temperature refrigerant on the compressor discharge side, which is guided to the third bypass circuit, with the refrigerant in the accumulator. Therefore, the fourth heat exchange unit vaporizes the refrigerant in the third bypass circuit and quickly moves it from the accumulator. Further, the refrigerant in the third bypass circuit is cooled by the refrigerant in the accumulator when passing through the fourth heat exchange section.

Further, when the temperature detecting means detects the temperature of the heat source medium, the control means controls the opening and closing of the fourth flow rate control device based on the temperature of the heat source medium detected by the temperature detecting means to circulate through the third bypass circuit. Adjust the flow rate of the cooling medium. Therefore, the control means may perform control such that the refrigerant is passed through the third bypass circuit to evaporate the refrigerant in the accumulator only in a state where the heat source temperature is low and the liquid refrigerant is likely to remain accumulated in the accumulator, for example. it can.

[0025]

【Example】

Example 1. FIG. 1 is a refrigerant circuit diagram showing a refrigeration cycle system of an embodiment according to the invention of claim 1, FIG. 2 is a control flowchart in a refrigeration cycle system of an embodiment of the invention of claim 1, and FIG. 3 is an invention of claim 1. FIG. 4 is a control block diagram in the refrigeration cycle system according to the embodiment of the present invention. In FIG. 1, 1 is a compressor, 2 is a four-way switching valve, 3 is a heat source side heat exchanger, 4a and 4b are first flow control devices,
5a and 5b are heat exchangers on the use side, 6 is an accumulator, 7
Is the heat source side heat exchanger 3 and the first flow rate control devices 4a, 4b
A second heat exchanging section for exchanging heat with the liquid refrigerant in the accumulator 6 by passing a part of the second refrigerant pipe 24 that connects the first refrigerant pipe 23 and the second refrigerant pipe 24. Bypass connection with the refrigerant pipe 24 and the second heat exchange section 7
A first bypass circuit for diverting a part of the refrigerant discharged from the low-pressure side to a low-pressure side, and a second flow rate control device 9 provided in the middle of the first bypass circuit 8 for decompressing the diverted refrigerant to a low-temperature low-pressure Reference numeral 10 denotes the refrigerant in the first bypass circuit 8 on the outlet side of the second flow rate control device 9 and the second refrigerant pipe 24 from the outlet side of the heat source unit side heat exchanger 3 to the connecting portion of the first bypass circuit 8. A first heat exchange part for exchanging heat with the refrigerant inside, 11 is a first
A temperature sensor for detecting the refrigerant temperature after exiting the first heat exchange section 10 in the bypass circuit 8 and a pressure sensor 12 for detecting the pressure on the low pressure side. Further, 13 is an accumulator 6
A third refrigerant pipe connecting the upper part of the inside to the suction side of the compressor 1, and 25 is a fourth refrigerant pipe connecting the discharge side of the compressor 1 and the inlet side of the heat source unit side heat exchanger 3. These first refrigerant pipe 23, second refrigerant pipe 24, third refrigerant pipe 13,
And, via the fourth refrigerant pipe 25, the compressor 1, the four-way switching valve 2, the heat source side heat exchanger 3, the first flow rate control device 4a,
4b and the use side heat exchangers 5a and 5b are mainly sequentially connected in an annular shape to form a main refrigerant circuit. Further, in FIG. 3, 22 receives the detection signals from the pressure sensor 12 and the temperature sensor 11, and at the same time, the first flow rate control device 4
It is an operation control unit that controls the operation of driving parts such as a and 4b. Since the present embodiment is an embodiment of a cooling cycle, the arrows in the figure indicate the direction of flow of the refrigerant during cooling.

The operation of the second flow control device 9 will be described with reference to FIG. The refrigerant in the first bypass circuit 8 in the gas-liquid two-phase state of low temperature and low pressure in the second flow rate control device 9 absorbs heat from the refrigerant from the second heat exchange section 7 in the first heat exchange section 10. By doing so, he is gradually gasified.
When the amount of the refrigerant flowing through the first bypass circuit 8 is large, the entire amount of the refrigerant does not become a gas, so that the outlet of the first bypass circuit 8 does not become overheated. At this time, if the amount of refrigerant bypass to the first bypass circuit 8 is large, the amount of refrigerant flowing to the use-side heat exchangers 5a and 5b will decrease, leading to a decrease in the capacity of the device. On the contrary, when the amount of the refrigerant flowing through the first bypass circuit 8 is small, the refrigerant in the first bypass circuit 8 becomes the first refrigerant.
Since the entire heat exchange section 10 is gasified, the heat absorbing effect disappears and the heat exchange amount in the first heat exchange section 10 decreases. The temperature sensor 11 and the pressure sensor 12 are the first
It is used to detect the state of the refrigerant at the outlet of the bypass circuit 8. The superheat degree SH of the refrigerant is usually obtained by the following equation based on the temperature t11 detected by the temperature sensor 11 and the pressure P12 detected by the pressure sensor 12. (Superheat degree SH) = (t11)-(f (P12)) Here, f (P12) represents the saturation temperature of the refrigerant at the pressure P12.

In the flowchart of FIG. 2, when the control is started in step S0, first, in step S1, 3
The control waits for 0 seconds. Thus, the control is made to stand by because the time until the refrigerant system stabilizes is taken into consideration when changing the opening degree of the second flow rate control device 9 in the repetitive control as shown in FIG. . And step S
If the superheat degree SH is greater than the preset predetermined value a at 2, it is determined that the bypass amount is small, and the opening degree of the second flow rate control device 9 is increased from the current opening degree SjP by the predetermined opening degree ΔSj. (Step S3), the process returns to step S1.
On the contrary, if SH ≦ a in step S2, it is determined that the refrigerant is in the gas-liquid two-phase state, and the opening degree of the second flow rate control device 9 is reduced by the predetermined opening degree ΔSj (step S4). Return to step S1. As shown in FIG. 1, the first heat exchange unit 10
By exchanging heat with the first heat exchange section 10 and by providing the second heat exchange section 7 by penetrating the refrigerant pipe that has exited the heat source unit side heat exchanger 3 into the accumulator 6 before the first heat exchange section 10. 1 Immediately after starting, even if the refrigerant distribution in the refrigerant circuit is biased and there is not much liquid refrigerant at the inlet of the first bypass circuit 8 and is accumulated in the accumulator 6, first, the liquid refrigerant in the accumulator 6 is By exchanging heat with, the refrigerant discharged from the heat source side heat exchanger 3 is brought into a supercooled state, and the degree of supercooling can be further increased in the first heat exchange section 10.

If the refrigerant becomes supercooled before the first heat exchange section 10 after a while after the start-up, there is no problem even if the liquid refrigerant in the accumulator 6 runs out. Therefore, the degree of supercooling can be increased, so that the control of the first flow rate control devices 4a and 4b can be performed without any problem. Further, the refrigerant can be surely divided into the plurality of utilization side heat exchangers 5a and 5b. At this time, since the inlet of the first bypass circuit 8 is located on the downstream side of the second heat exchange unit 7 or the first heat exchange unit 10, the refrigerant at the inlet of the second flow rate control device 9 is always Since it becomes a liquid refrigerant, the flow rate control of the second flow rate control device 9 can be performed without any problem. From the above description, it is not necessary to store the refrigerant in the accumulator 6 more than necessary, and even if the refrigerant is concentrated in the accumulator 6, a sufficient degree of supercooling can be quickly secured, so that the cost of the air conditioner can be reduced. It becomes possible to raise down and trust.

Example 2. In the first embodiment, the second heat exchange section 7
Although the first heat exchange section 10 is arranged on the downstream side of the above, the first heat exchange section 10 may be arranged on the upstream side of the second heat exchange section 7 as shown in FIG. Even in that case, since the inlet of the first bypass circuit 8 is arranged downstream of the second heat exchange unit 7 so as to always obtain a sufficiently supercooled liquid refrigerant, the configuration of the first embodiment is not provided. The same effect is exhibited.

Example 3. FIG. 5 is a refrigerant circuit diagram showing a refrigeration cycle system of an embodiment according to the invention of claim 2, FIG.
FIG. 7 is a partial cutaway view showing a main part of a heat exchange section in a refrigeration cycle system according to an embodiment of the present invention. In FIG. 5, the main components and the operation thereof are almost the same as those of the first embodiment, except that the second heat exchange section 7 is omitted and the first heat exchange section 10 is arranged in the accumulator 6 as it is. In this way, by disposing the first heat exchange unit 10 in the accumulator 6, the first heat exchange unit 10
Can exchange heat with the liquid refrigerant in the accumulator 6, so only one heat exchange section is required. FIG. 6 shows an embodiment of the first heat exchange section 10 provided inside the accumulator 6. In FIG. 6, a first bypass circuit 8 is provided inside, and a double pipe in which the refrigerant discharged from the heat source side heat exchanger 3 flows outside is provided as a first heat exchange section 10 penetrating through the accumulator 6. ing.

In this way, by providing the heat exchange section having the first bypass circuit 8 in the accumulator 6, the second
While ensuring a sufficient degree of supercooling with the flow control device 9 of
When the liquid is stored in the accumulator 6, the parts that can exchange heat with the liquid are gathered in one place, so that it is compact and the number of parts is small. Further, due to the double pipe system in which the first bypass circuit 8 is arranged inside the first heat exchange unit 10, there is a certain amount of liquid in the accumulator 6, and in addition, the first bypass circuit 8 side If refrigerant control is also performed, the refrigerant flowing out of the heat source unit side heat exchanger 3 and flowing through the second refrigerant pipe 24 can radiate heat to both the inside and the outside, so that a sufficient degree of supercooling can be secured quickly. Therefore, the reliability of the air conditioner will be further improved.

Example 4. FIG. 7 is a refrigerant circuit diagram showing a refrigeration cycle system according to an embodiment of the present invention. In FIG. 7, 1 is a compressor, 2 is a four-way switching valve, 3 is a heat source side heat exchanger, 4a and 4b are first flow rate control devices,
5a and 5b are heat exchangers on the use side, 6 is an accumulator, 1
3 is a third refrigerant pipe for returning the gas refrigerant mainly from the upper part of the accumulator 6 to the compressor 1, and 14 is an accumulator 6
The oil return circuit for returning the lubricating oil dissolved in the liquid refrigerant inside to the compressor 1 side together with the liquid refrigerant, 7a is the refrigerant in the oil return circuit 14 and the second refrigerant pipe on the outlet side of the heat source side heat exchanger 3 It is a third heat exchange unit for exchanging heat with the refrigerant in 24. The structure of the main refrigerant circuit is similar to that of the above-described embodiment. At the bottom of the accumulator 6, the lubricating oil discharged from the compressor 1 and recirculating in the refrigerant circuit and the liquid refrigerant always exist as a mixed liquid, and at least the lubricating oil in the mixed liquid is returned. Oil must be returned to the compressor 1 through the circuit 14.

Here, as shown in FIG. 7, since the third heat exchange section 7a is provided in the middle of the oil return circuit 14, the low temperature liquid refrigerant flowing in the oil return circuit 14 absorbs heat and approaches a gas state. . On the contrary, the high-temperature and high-pressure gas-liquid two-phase flowing in the heat source unit side heat exchanger 3 or the refrigerant having a slight supercooling degree radiates heat in the third heat exchanging portion 7a, thereby Grows larger. In this way, since the liquid refrigerant is gasified from the liquid in the oil return circuit 14, only the lubricating oil returns to the compressor 1, so that there is no fear of damaging the compressor 1 due to the liquid back of the refrigerant. Further, even if an excessive amount of liquid refrigerant is not put in the accumulator 6, the subcooling degree of the refrigerant sent to the first flow rate control devices 4a, 4b can be controlled by a small amount of the refrigerant accompanying the oil return and a simple circuit. Can be increased. This allows
Since the split flow to the plurality of use-side heat exchangers 5a and 5b and the flow rate controllability in the first flow rate control devices 4a and 4b are also stable, the reliability of the air conditioner can be greatly improved. Since the oil return circuit 14 needs to return a small amount of the mixed liquid in the accumulator 6, it is preferable to connect the oil return circuit 14 to the bottom of the accumulator 6 or a portion close thereto. Moreover, since the third refrigerant pipe 13 is for returning the gas refrigerant in the accumulator 6 to the suction side of the compressor 1,
It suffices that the open end of the accumulator side is communicated with the upper part of the accumulator 6, and the accumulator 6
The mounting position with respect to is not particularly limited, and may be, for example, the casing upper surface, the casing side surface, or the casing bottom surface of the accumulator 6.

Example 5. FIG. 8 is a refrigerant circuit diagram showing a refrigeration cycle system of an embodiment according to the invention of claims 5 and 6. In FIG. 8, in addition to the configuration of the fourth embodiment, a second bypass that bypasses a part of the refrigerant that has passed through the third heat exchange section 7a from the heat source side heat exchanger 3 to the inlet side of the accumulator 6 A circuit 8a, a third flow rate control device 9a for adjusting the refrigerant flow rate of the second bypass circuit 8a,
The oil return circuit 14 is provided with a temperature sensor 15 for detecting the temperature of the refrigerant flowing out of the third heat exchange section 7a, and a pressure sensor 12 for detecting the pressure on the low pressure side. The structure of the main refrigerant circuit is similar to that of the above-described embodiment. Here, an example of the control of the third flow rate control device 9a will be described with reference to FIG.
This will be shown based on the control flowchart of FIG. FIG. 10 is a control block diagram in the refrigeration cycle system of one embodiment according to the inventions of claims 5 and 6.

The refrigerant in the oil return circuit 14 is gradually gasified by absorbing heat in the third heat exchange section 7a. At this time, if the amount of liquid in the accumulator 6 is too large, the amount of liquid flowing through the oil return circuit 14 increases due to the liquid column pressure, and the refrigerant at the outlet of the oil return circuit 14 does not become overheated. If the refrigerant returns to the compressor 1 in such a two-phase wet state, the compressor 1 may be damaged due to liquid back. On the contrary, when the amount of the liquid refrigerant in the accumulator 6 is extremely small, the amount of the refrigerant flowing in the oil return circuit 14 is also small, so that all of this refrigerant is gasified in the third heat exchange section 7a and the endothermic effect is almost eliminated. The amount of heat exchange in the heat exchange part 7a falls. The pressure sensor 12 and the temperature sensor 15 are used to detect the refrigerant state at the outlet of the oil return circuit 14. The superheat degree SH of the refrigerant is normally obtained by the following equation based on the temperature t15 detected by the temperature sensor 15 and the pressure P12 detected by the pressure sensor 12. (Superheat degree SH) = (t15)-(f (P12)) Here, f (P12) represents the saturation temperature of the refrigerant at the pressure P12.

In FIG. 9, the step of waiting the control for 60 seconds in step S5 is to stabilize the refrigerant system while changing the opening of the third flow control device 9a in the repetitive control as shown in the flowchart. This is because the time to do so was taken into consideration. Then, if the superheat degree SH is larger than the predetermined value b ₁ set in advance in step S6, it is determined that the liquid amount in the accumulator 6 is small, and the opening degree of the third flow rate control device 9a is set to the present opening degree. Degree SjP to predetermined opening ΔS
It is increased by j (step S7), and the process returns to step S5. On the contrary, if SH ≦ b ₁ in step S6, the process proceeds to step S8. If the superheat degree SH is smaller than the predetermined value b ₂ (<b ₁ ) set in advance in step S8, it is determined that the amount of liquid in the accumulator 6 is excessive, and in step S9, the third The opening degree of the flow rate control device 9a is reduced by the predetermined opening degree ΔSj, and the process returns to step S5.
On the other hand, if the degree of superheat SH is b ₂ or more and b ₁ or less in step S8, it is determined that the liquid amount is excessive, and the current opening SjP
Is maintained as it is (step S10), and step S5
Return to

As described above, by providing the second bypass circuit 8a and the third flow rate control device 9a, for example, when the amount of the refrigerant in the refrigerant circuit is insufficient, the liquid refrigerant is accumulated in the accumulator 6. When the amount of liquid is high and the liquid having a high lubricating oil concentration flows through the oil return circuit 14, the liquid refrigerant is returned to the accumulator 6 by the third flow rate control device 9a, and a new liquid is stored in the accumulator 6. Since the refrigerant accumulates, the amount of heat exchange in the third heat exchange section 7a can be constantly maintained, and the amount of refrigerant to be bypassed to the accumulator 6 can be adjusted. Therefore, liquid back to the compressor 1 does not occur due to excessive bypassing by the second bypass circuit 8a.
It is possible to sufficiently improve the reliability of the air conditioner without reducing the degree of supercooling of the refrigerant flowing to the flow rate control devices 4a and 4b and without imposing a burden on the compressor 1.

Example 6. 11 is a refrigerant circuit diagram showing a refrigeration cycle system of an embodiment according to the invention of claim 7, FIG. 12 is a control flowchart in the refrigeration cycle system of an embodiment of the invention of claim 8, and FIG.
FIG. 3 is a control block diagram in a refrigeration cycle system of an embodiment according to the invention of FIG. In FIG. 11, 1 is a compressor,
2 is a four-way switching valve, 3 is a heat source unit side heat exchanger, 4a and 4b are first flow rate control devices, 5a and 5b are utilization side heat exchangers, and 6
Is an accumulator, 7b is a discharge gas accumulator 6
The fourth through which heat is exchanged in the accumulator 6 by passing the inside.
Heat exchange section, 8 is a first bypass circuit for branching a part of the refrigerant discharged from the fourth heat exchange section 7b to the low pressure side, and 9 is a first
The second flow rate control device 10, which is provided in the middle of the bypass circuit 8 and reduces the pressure of the bypassed refrigerant to a low temperature and low pressure, exits from the fourth heat exchange section 7b downstream of the second flow rate control device 9. First, the refrigerant is further heat-exchanged with the refrigerant in the first bypass circuit 8 that has become low temperature and low pressure in the second flow rate control device 9.
, The heat exchange unit 11 is a temperature sensor that detects the temperature of the refrigerant after flowing out of the first heat exchange unit 10 in the first bypass circuit 8, 12 is a pressure sensor that detects the pressure on the low pressure side, and 16 is the discharge A third bypass circuit for flowing the gas to the fourth heat exchange section 7b, and 17 and 18 are valves for switching the discharge gas to either the heat source side heat exchanger 3 or the fourth heat exchange section 7b (respectively. , An example of a fourth flow rate control device, 19 is a heat source medium temperature (here, an air-cooling type heat source device is adopted,
A temperature sensor (an example of temperature detection means) that detects the outside air temperature), 20 is a pressure sensor that detects the pressure on the high-pressure side, and 21 is the refrigerant temperature after flowing out of the first heat exchange unit 10. It is a temperature sensor. The structure of the main refrigerant circuit is similar to that of the above-described embodiment. Since this embodiment is an embodiment of a cooling cycle, the arrows in the figure indicate the flow direction of the refrigerant during cooling. Operation of second flow control device 9 and first
Since the function of the heat exchange section 10 is the same as that of the first embodiment, the description thereof will be omitted.

Next, using the flowchart of FIG.
The operation of the valves 17 and 18 will be briefly described. First, in step S11, control by the operation control unit 22 (see FIG. 13, an example of control means) is started, and at this time, the compressor 1 is assumed to be in a state immediately before startup. In step S12, it is determined whether the outside air temperature t19 immediately before starting is lower than the predetermined temperature c. If the outside air temperature t19 is lower than a preset predetermined temperature c, it is highly possible that the liquid refrigerant is accumulated in the accumulator 6, and the valve 17 is opened (ON) in step S13, and in step S14. Close valve 18 (O
FF) allows the discharge gas to pass through the accumulator 6 without passing through the heat source side heat exchanger 3. Then, in step S15, the compressor 1 is activated (ON).
On the other hand, if the outside air temperature t19 ≧ c in step S12,
The operation control unit 22 does not collect much refrigerant in the accumulator 6, and the pressure on the high pressure side immediately rises,
As a result, the pressure on the low pressure side also rises, the amount of refrigerant circulation in the compressor 1 also increases, and the liquid refrigerant in the accumulator 6 moves faster, and it is determined that the degree of supercooling in the first heat exchange unit 10 tends to be sufficient. To do. Therefore, the operation control unit 22 opens the valve 18 (ON) and closes the valve 17 (O) as in normal operation.
FF) so that the refrigerant flows through the heat exchanger 3 on the heat source unit side to start the compressor 1 (steps S18, S19,
S20), the valves 17 and 18 are left as they are, and the control ends (step S23).

After the compressor 1 is started in step S15 as described above, the pressure P20 detected by the pressure sensor 20 in step S16 is a preset value e.
To determine if If the pressure P20 exceeds the predetermined value e, the valve 18 is opened (ON) in step S21, and the valve 17 is closed (OFF) in step S22.
As usual, the refrigerant is allowed to flow through the heat exchanger 3 on the heat source device side, the pressure on the high pressure side is reduced, and the control ends (step S2).
3). On the other hand, if the pressure P20 on the high-pressure side is equal to or lower than the predetermined value e in step S16, the subcooling degree SC of the refrigerant at the outlet of the first heat exchange unit 10 is set to a predetermined value f (<e) in step S17. Judge whether it is over.
The degree of supercooling SC can be easily calculated by the following equation. (Supercooling degree SC) = f (P20) -T21 Here, f (P20) is the saturation temperature of the refrigerant at the pressure P20 on the high pressure side. Further, T21 is the refrigerant temperature at the outlet of the first heat exchange unit 10 detected by the preset temperature sensor 21. Then, the calculated supercooling degree SC
Is larger than the predetermined value f, it is determined that the liquid refrigerant existing in the accumulator 6 has evaporated and moved to the first heat exchange section 10, and the valve 18 is operated in steps S21 and S22.
After opening the valve 17 and closing the valve 17, the control ends in step S23.

As described above, when the compressor 1 is started, especially when the outside air temperature, which is a heat source, is low, a part of the discharge gas is selectively passed through the fourth heat exchanging portion 7b to the accumulator 6
By flowing the inside, even when the refrigerant is accumulated in the accumulator 6, the refrigerant can be evaporated and quickly moved from the accumulator 6. Therefore, the second
By the control of the flow rate control device 9, the first heat exchange unit 10 can quickly secure a large degree of supercooling. as a result,
When there are a plurality of use side heat exchangers such as 5a and 5b, the distribution of the refrigerant and the opening control of the first flow rate control devices 4a and 4b can be performed without problems, and the refrigerant is biased when the outside air temperature is low. Therefore, the reliability of the air conditioner in the operation in a state where it is easily distributed can be sufficiently enhanced.

[0042]

According to the present invention, the refrigerant in the second refrigerant pipe flowing out from the heat source side heat exchanger is heat-exchanged with the refrigerant in the accumulator, and at low temperature and low pressure flowing in the first bypass circuit. Since heat is exchanged with the refrigerant, it is possible to sufficiently secure the degree of supercooling of the refrigerant flowing into the first flow rate control device without depending on the refrigerant distribution in the main refrigerant circuit immediately before the compressor is started. At the same time, the refrigerant in the accumulator can be evaporated and removed from the accumulator. Therefore, the performance of the refrigeration cycle system can be improved.

Further, since the first heat exchanging portion and the second heat exchanging portion are integrally formed and arranged so as to be able to conduct heat to, for example, the inside or the outside of the accumulator, the structure is simple. Therefore, it can be configured with a small number of parts. Therefore, improvement in manufacturing efficiency and cost reduction can be realized.

Since the refrigerant flowing in the second refrigerant pipe at the position corresponding to the second heat exchange section is cooled from the inside and outside of the second refrigerant pipe, the first flow rate control is performed. The refrigerant flowing into the device can reach a sufficient degree of supercooling in a short time. Therefore, the performance of the refrigeration cycle system can be improved.

Further, the third refrigerant for exchanging heat between the refrigerant in the oil return circuit connected from the accumulator to the compressor suction side and the refrigerant in the second refrigerant pipe flowing out from the heat source side heat exchanger.
Since the heat exchange section is provided, it is possible to sufficiently secure the degree of supercooling of the refrigerant flowing into the first flow rate control device by using an essential oil return circuit having a function of oil return. Moreover, since a simple structure that uses an oil return circuit is adopted, cost reduction can be realized, and liquid backing when returning oil to the suction side of the compressor is eliminated and damage to the compressor is not caused. The reliability of the refrigeration cycle system can be improved.

Moreover, in addition to the structure of claim 4, a second bypass circuit is provided so that a part of the refrigerant flowing into the first flow rate control device is returned to the accumulator by the second bypass circuit. Even if the amount of the refrigerant inside is originally small, the refrigerant to be evaporated in the third heat exchange section can be secured in the accumulator. Therefore, since the amount of heat exchange in the third heat exchange section can always be maintained above a certain level,
The reliability of the refrigeration cycle system can be improved.

According to the fifth aspect of the invention, the second bypass circuit is provided with the third flow rate control device to control the flow rate of the refrigerant flowing through the second bypass circuit. Therefore, the refrigerant to the accumulator is controlled. The return amount of can be adjusted appropriately. Therefore, for example, the compressor will not be damaged due to the liquid back to the compressor caused by returning more refrigerant than necessary to the accumulator. as a result,
The refrigerant flowing into the first flow rate control device can be appropriately returned from the accumulator to the compressor while ensuring a sufficient degree of supercooling, thereby improving the reliability and performance of the refrigeration cycle system. be able to.

Since a part of the high-temperature refrigerant on the discharge side of the compressor is introduced into the third bypass circuit and heat-exchanged with the refrigerant in the accumulator by the fourth heat exchange section, a relatively large amount is accumulated in the accumulator. Even when the refrigerant is accumulated, the refrigerant can be vaporized by the heat from the fourth heat exchange unit and quickly moved from the accumulator.
On the other hand, since the refrigerant in the third bypass circuit is cooled by the refrigerant in the accumulator and sent to the first heat exchange section when passing through the fourth heat exchange section, it does not hinder the operation. Therefore, the performance of the refrigeration cycle system can be improved.

Further, the temperature of the heat source medium is detected by the temperature detecting means, and the fourth flow rate control device is controlled by the control means based on the detected temperature of the heat source medium to adjust the refrigerant flow rate. With respect to the movement of the refrigerant from the inside, it is possible to realize fine control according to the temperature of the heat source medium, and it is possible to improve the reliability of the refrigeration cycle system.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing a refrigeration cycle system according to an embodiment of the present invention.

FIG. 2 is a control flowchart in the refrigeration cycle system of one embodiment according to the invention of claim 1.

FIG. 3 is a control block diagram in the refrigeration cycle system of one embodiment according to the invention of claim 1.

FIG. 4 is a refrigerant circuit diagram showing a refrigeration cycle system of another embodiment according to the invention of claim 1.

FIG. 5 is a refrigerant circuit diagram showing a refrigeration cycle system of an embodiment according to the invention of claim 2.

FIG. 6 is a partial cutaway view showing a main part of a heat exchange section in a refrigeration cycle system according to an embodiment of the present invention.

FIG. 7 is a refrigerant circuit diagram showing a refrigeration cycle system of an embodiment according to the invention of claim 4.

FIG. 8 is a refrigerant circuit diagram showing a refrigeration cycle system of an embodiment according to the invention of claims 5 and 6.

FIG. 9 is a control flowchart in the refrigeration cycle system of one embodiment according to the inventions of claims 5 and 6.

FIG. 10 is a control block diagram in the refrigeration cycle system of one embodiment according to the inventions of claims 5 and 6.

FIG. 11 is a refrigerant circuit diagram showing a refrigeration cycle system of one embodiment according to the invention of claim 7.

FIG. 12 is a control flowchart in the refrigeration cycle system of one embodiment according to the invention of claim 8;

FIG. 13 is a control block diagram in a refrigeration cycle system of an embodiment according to the invention of claim 8.

FIG. 14 is a refrigerant circuit diagram showing an example of a refrigeration cycle system used in a conventional air conditioner.

FIG. 15 is a refrigerant circuit diagram showing another example of a refrigeration cycle system used in a conventional air conditioner.

[Explanation of symbols]

1 compressor, 3 heat source side heat exchanger, 4a 1st flow control device, 4b 1st flow control device, 5a use side heat exchanger, 5b use side heat exchanger, 6 accumulator,
7 2nd heat exchange part, 7a 3rd heat exchange part, 7b 4th heat exchange part, 8 1st bypass circuit, 8a 2nd bypass circuit, 9 2nd flow control device, 9a 3rd Flow rate control device, 10 1st heat exchange part, 10a 1st heat exchange part, 10b 1st heat exchange part, 13 3rd refrigerant piping, 14 oil return circuit, 15 temperature sensor, 16 3rd
Bypass circuit, 17 valves (4th flow controller), 1
8 valves (4th flow control device), 19 temperature sensor (temperature detection means), 22 operation control part (control device), 23 1st refrigerant piping, 24 2nd refrigerant piping, 25 4th refrigerant piping.

Claims (8)

[Claims] 1. A compressor, a heat source side heat exchanger, a first flow rate control device, a use side heat exchanger, and an accumulator, and connects the use side heat exchanger outlet side and the accumulator inlet side. A main refrigerant circuit including at least a first refrigerant pipe, a second refrigerant pipe connecting the heat source unit side heat exchanger outlet side and the use side heat exchanger inlet side, and a second flow rate control device Then, the first bypass circuit connecting the second refrigerant pipe and the first refrigerant pipe, the refrigerant in the first bypass circuit on the outlet side of the second flow rate control device, and the heat source unit side heat exchange A first heat exchanging section for exchanging heat with the refrigerant in the second refrigerant pipe from the outlet side to the connecting portion of the first bypass circuit; and the refrigerant in the second refrigerant pipe and A second heat exchanging section for exchanging heat with the refrigerant in the accumulator. Refrigeration cycle system. 2. A compressor, a heat source side heat exchanger, a first flow rate control device, a utilization side heat exchanger, and an accumulator, and the utilization side heat exchanger outlet side and the accumulator inlet side are connected. A main refrigerant circuit including at least a first refrigerant pipe, a second refrigerant pipe connecting the heat source unit side heat exchanger outlet side and the use side heat exchanger inlet side, and a second flow rate control device Then, the first bypass circuit connecting the second refrigerant pipe and the first refrigerant pipe, the refrigerant in the first bypass circuit on the outlet side of the second flow rate control device, and the heat source unit side heat exchange A first heat exchanging section for exchanging heat with the refrigerant in the second refrigerant pipe from the outlet side to the connecting portion of the first bypass circuit; and the refrigerant in the second refrigerant pipe and A second heat exchanging unit for exchanging heat with the refrigerant in the accumulator, and A refrigeration cycle system, wherein a first heat exchange section and the second heat exchange section are integrally provided in the accumulator. 3. The first heat exchange section accommodates the first bypass circuit on the outlet side of the second flow rate control device in the second refrigerant pipe at a position corresponding to the second heat exchange section. The refrigeration cycle system according to claim 2, wherein the refrigeration cycle system is configured. 4. A compressor, a heat source side heat exchanger, a first flow rate control device, a use side heat exchanger, and an accumulator, and the use side heat exchanger outlet side and the accumulator inlet side are connected. A first refrigerant pipe, a second refrigerant pipe connecting the heat source unit side heat exchanger outlet side and the use side heat exchanger inlet side, an upper part in the accumulator and the compressor suction side A main refrigerant circuit including at least the refrigerant pipe 3;
An oil return circuit that connects the lower portion of the accumulator and the third refrigerant pipe to return the lubricating oil containing the refrigerant of the accumulator to the compressor suction side, the lubricating oil containing the refrigerant in the oil return circuit, and A refrigeration cycle system comprising: a third heat exchange section that exchanges heat with the refrigerant in the second refrigerant pipe. 5. The refrigeration cycle system according to claim 4, further comprising a second bypass circuit that connects the second refrigerant pipe and the first refrigerant pipe. 6. The refrigeration cycle system according to claim 5, wherein the second bypass circuit is provided with a third flow rate control device that adjusts a flow rate of the refrigerant flowing through the second bypass circuit. 7. A compressor, a heat source side heat exchanger, a first flow rate control device, a use side heat exchanger, and an accumulator, and connects the use side heat exchanger outlet side and the accumulator inlet side. A first refrigerant pipe, a second refrigerant pipe connecting the heat source unit side heat exchanger outlet side and the utilization side heat exchanger inlet side, the compressor discharge side and the heat source unit side heat exchanger inlet side A main refrigerant circuit that includes at least a fourth refrigerant pipe that connects the first refrigerant pipe and the second refrigerant pipe, and the second refrigerant pipe and the first refrigerant circuit.
A first bypass circuit for connecting the first bypass circuit to the refrigerant pipe, and the refrigerant in the first bypass circuit on the outlet side of the second flow rate control device and the heat source unit side heat exchanger from the outlet side to the first bypass circuit. A first heat exchanging portion for exchanging heat with the refrigerant in the second refrigerant pipe up to the connecting portion, and a fourth flow rate control device, and the fourth refrigerant pipe and the heat source unit side heat exchange. First from the exit side
A third bypass circuit that connects the second refrigerant pipe to the heat exchanging part of the second heat exchanger, and a fourth heat exchange that performs heat exchange between the refrigerant in the third bypass circuit and the refrigerant in the accumulator. A refrigeration cycle system, comprising: 8. A temperature detecting means for detecting a temperature of a heat source medium which passes through a heat source side heat exchanger and exchanges heat with a refrigerant in the heat source side heat exchanger, and the temperature detecting means detects the temperature. 8. The refrigeration cycle system according to claim 7, further comprising: a control unit that controls the flow rate of the refrigerant by the fourth flow rate control device based on the heat source medium temperature that has been set.