JPH11142011A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure sufficiently a pressure difference between an inlet side and an outlet side of a heat exchanger of a using side and execute stably a refrigerant circulating operation with respect to a refrigerating device equipped with a plurality of heat exchangers of the using side mutually connected in parallel even in case an evaporating capacity of a heat exchanger of a heat source side is lowered during heating. SOLUTION: In a heating operation of a refrigerating device, an opening ratio of an indoor motor operated valve EV-2 and that of an outdoor motor operated valve EV-1 are adjusted so as to maintain a supercooling ratio of an outlet side of an indoor heat exchanger 4 at a constant level and maintain a superheating ratio of an outlet side of an outdoor heat exchanger 3 at a constant level, whereas an upper limit value of the opening ratio of the indoor motor operated valve EV-2 is lowered as the opening ratio thereof becomes small when the opening ratio of the indoor motor operated valve EV-2 is smaller than a prescribed opening ratio thereof in case an ambient temperature is low. Therefore, it is possible to secure the pressure difference between the inlet side and the outlet side of the indoor heat exchanger 4 by limiting the upper limit value of the opening ratio of this indoor motor operated valve EV-2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigeration system,
In particular, the present invention relates to a countermeasure for stably performing a refrigerant circulation operation for a device having a plurality of use-side heat exchangers connected in parallel with each other.

[0002]

2. Description of the Related Art Conventionally, a refrigeration system used as a refrigerant circuit or the like of an air conditioner has been disclosed in Japanese Patent Laid-Open No. 6-257.
One disclosed in Japanese Patent No. 875 is known. The air conditioner disclosed in this publication includes an outdoor unit,
It is configured as a so-called indoor multi-machine including a plurality of indoor units connected in parallel to each other. The outdoor unit contains a compressor, an outdoor heat exchanger, and an outdoor electric valve, and each indoor unit contains an indoor electric valve and an indoor heat exchanger. These devices are connected by a refrigerant pipe to form a closed circuit refrigerant circuit.
Further, the outdoor unit is provided with a four-way switching valve, and the circulation direction of the refrigerant is reversible.

During indoor heating, the high-pressure gas refrigerant discharged from the compressor exchanges heat with the indoor air in each indoor heat exchanger, condenses, passes through the indoor electric valve and the outdoor electric valve, and then passes through the outdoor heat exchanger. And heat exchange with the outside air to evaporate and return to the compressor. At this time, the opening of the indoor motor-operated valve is adjusted so that the degree of subcooling of the refrigerant on the outlet side of the indoor heat exchanger is constant. on the other hand,
The degree of opening of the outdoor motor-operated valve is adjusted so that the degree of superheat of the refrigerant at the outlet of the outdoor heat exchanger is constant. Thereby, the room can be stably heated. On the other hand, during indoor cooling, the four-way switching valve is switched so that the refrigerant circulation direction is opposite to the above.

[0004]

By the way, in this type of apparatus, when heating in a situation where the outside air temperature is extremely low, the opening degree of the outdoor motor-operated valve is reduced because the evaporation capacity of the outdoor heat exchanger is insufficient. I do. That is, by increasing the degree of decompression of the refrigerant flowing through the outdoor heat exchanger serving as the evaporator, the degree of superheat of the refrigerant at the outlet side of the outdoor heat exchanger is maintained, and the refrigerant at the evaporator outlet side is prevented from becoming wet. To ensure the reliability of the compressor.

[0005] In the situation where the opening degree of the outdoor motor-operated valve is reduced as described above, the circulation resistance of the circulating refrigerant is increased by the outdoor motor-operated valve, and the refrigerant circulation amount in the entire circuit is reduced. Accordingly, the degree of supercooling of the refrigerant in the indoor heat exchanger increases, so that in each indoor unit, the degree of opening of the indoor motor-operated valve that performs the above-described subcooling degree constant control increases.

However, when the degree of opening of the indoor motor-operated valve is increased, the pressure at the outlet of the indoor heat exchanger does not sufficiently decrease, and the pressure difference between the inlet and the outlet of the indoor heat exchanger is reduced. It will be smaller. Then, when the opening degree of the outdoor electric valve is reduced to a state close to the fully closed state, the indoor electric valve is substantially fully opened. In such a situation, the pressure difference between the inlet side and the outlet side of the indoor heat exchanger almost disappears, which hinders the circulation of the refrigerant. In particular, in the indoor multi-unit having a plurality of indoor units as described above, when the installation height positions of the indoor units are different, the liquid refrigerant is supplied to the indoor heat exchanger of the indoor unit located on the lower side. Accumulates, and this heat exchanger can hardly exercise its capacity. Specifically, when this device is used for air conditioning in a building, although the heating operation is performed favorably in the indoor unit on the upper floor, the indoor unit on the lower floor can hardly be heated. I will.

In addition, when a large amount of liquid refrigerant is accumulated in some of the indoor heat exchangers, the amount of refrigerant circulating in the entire circuit is insufficient, and all the indoor units have sufficient heating capacity. In some cases, you may not be able to demonstrate it.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a refrigeration system having a plurality of use-side heat exchangers connected in parallel with each other. Even if the evaporation capacity of the heat exchanger is reduced, the pressure difference between the inlet side and the outlet side of the use side heat exchanger is sufficiently ensured to stably perform the refrigerant circulation operation.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a heat source side heat exchanger in which the evaporating capacity is reduced and the opening of a heat source side control valve is reduced. When the degree of opening of the control valve becomes large, the pressure difference between the inlet side and the outlet side of the use side heat exchanger can be sufficiently secured by providing a limit to the upper limit of the use side control valve. I did it.

More specifically, as shown in FIG. 1, the invention according to claim 1 includes a compressor (1), a plurality of use-side heat exchangers (4, 4, 4) connected in parallel with each other, Adjustable user-side control valve
(EV-2, EV-2, EV-2) and the heat source side control valve (EV-
1) Assume a refrigeration apparatus including a refrigerant circuit (5) in which a heat source side heat exchanger (3) is connected by refrigerant piping. In particular, during the heat radiation operation in which the refrigerant condenses in the use side heat exchanger (4, 4, 4) and the refrigerant evaporates in the heat source side heat exchanger (3), the use side heat exchanger (4, 4, 4) User-side control means (11) for adjusting the opening of the user-side control valves (EV-2, EV-2, EV-2) so as to keep the degree of subcooling of the refrigerant at the outlet side constant, and a heat-source-side heat exchanger It is assumed that the apparatus includes a heat source side control means (12) for adjusting the opening of the heat source side control valve (EV-1) so as to keep the refrigerant superheat degree at the outlet side of (3) constant. As a feature of the present invention, during the heat dissipation operation, the evaporation capability of the heat source side heat exchanger (3) is reduced and the heat source side control means (1
When the opening of the heat source side control valve (EV-1) becomes equal to or less than the predetermined opening due to 2), the use side control valves (EV-2, EV-2, EV -2) is provided with a restricting means (13) for restricting the upper limit value of the opening to a predetermined value or less to secure a pressure difference between the inlet side and the outlet side of the use side heat exchanger (4, 4, 4). That is.

According to this specific matter, during the heat radiating operation of the refrigeration system, the gas refrigerant discharged from the compressor (1) is condensed in the use side heat exchangers (4, 4, 4), and the use side control valve (EV-2) , EV-2, EV-2)
After passing through the heat source side control valve (EV-1) and the heat source side heat exchanger (3)
To evaporate. At this time, the opening degree of the use side control valve (EV-2, EV-2, EV-2) is adjusted by the use side control means (11), and the outlet side of the use side heat exchanger (4, 4, 4). Is kept constant. On the other hand, the opening of the heat source side control valve (EV-1) depends on the heat source side control means.
Adjusted by (12), the degree of superheat of the refrigerant at the outlet side of the heat source side heat exchanger (3) is kept constant. In such a situation, when the evaporation capacity of the heat source side heat exchanger (3) is reduced and the opening degree of the heat source side control valve (EV-1) is reduced by the heat source side control means (12), the refrigerant circulation User-side heat exchanger (4,
4,4) The use side control valve (EV-2, EV-2, EV-2) by the use side control means (11) in order to avoid an increase in the subcooling degree of the refrigerant on the outlet side.
The degree of opening increases. Then, when the opening of the heat source side control valve (EV-1) becomes equal to or less than the predetermined opening, the use side control valve (EV-2, EV-2,
In order to prevent the opening of EV-2, EV-2) from becoming too large, the restricting means (13) sets the upper limit of the opening of the usage-side control valve (EV-2, EV-2, EV-2). Limit the value to a specified value or less. This avoids a situation in which there is no pressure difference between the inlet side and the outlet side of the use side heat exchangers (4, 4, 4) and the refrigerant cannot flow. In addition, as a situation where the evaporation capacity of the heat source side heat exchanger (3) is reduced, when the heat source side heat exchanger (3) exchanges heat with outside air, the outside air temperature becomes extremely low. and so on.

The second aspect of the present invention is the first aspect of the present invention.
The use side heat exchanger in which the effect according to the described invention is remarkably obtained.
The arrangement state of (4,4,4) was identified. That is, claim 1
In the refrigeration apparatus described above, the arrangement height positions of the use-side heat exchangers (4, 4, 4) are different from each other.

According to this specific matter, the use side control valve (EV-2,
EV-2, EV-2) opening degree increases, and each user-side heat exchanger (4,
In the situation where the pressure difference between the inlet side and the outlet side in (4) and (4) becomes small, the liquid refrigerant tends to accumulate in the use side heat exchanger (4) where the installation height is low. In some cases, the side heat exchanger (4) could hardly exercise its capacity. In the present invention, the use-side control valve (EV-2, EV-2, EV-
By limiting the upper limit of the opening of 2), each use side heat exchanger
(4,4,4) it is possible to distribute the refrigerant evenly,
A situation in which the refrigerant accumulates in some of the use-side heat exchangers (4) does not occur.

The invention according to claim 3 embodies a state where the opening upper limit value is restricted by the restricting means (13). That is, in the refrigeration apparatus according to claim 1, the restricting means (13)
However, when the opening degree of the heat source side control valve (EV-1) becomes less than or equal to a predetermined opening degree by the heat source side control means (12), the use side control valve (EV-2, EV- 2, EV-2) gradually lowers the upper limit of the opening.

According to this specific matter, the use side control valve (EV-2,
If the upper limit value of the opening of the EV-2, EV-2) is suddenly reduced, the opening becomes smaller than necessary and the usage-side control valve (EV-2, EV-2)
-2, EV-2) There is a possibility that the degree of supercooling on the outlet side may become too large, but in the present invention, by gradually decreasing this opening, the behavior of the refrigerant circulation operation does not occur. The operation according to the first aspect of the present invention is obtained.

According to a fourth aspect of the present invention, the present invention is applied to an air conditioner. That is, in the refrigeration apparatus according to claim 1, the use side heat exchanger is an indoor heat exchanger (4, 4, 4) disposed in the air-conditioned room, and the heat source side heat exchanger is disposed outside the room. The configuration is an outdoor heat exchanger (3).

According to the specific items, the apparatus to which the present invention is applied can be embodied, and the refrigerant can be evenly supplied to the indoor heat exchangers (4, 4, 4) disposed in the respective rooms to heat the respective rooms. Can be performed favorably.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is a case where the refrigeration apparatus according to the present invention is applied to an air conditioner for building air conditioning.

-Description of Refrigerant Circuit- As shown in FIG. 1, the air conditioner according to the present embodiment includes one outdoor unit (A) and a plurality (three in this embodiment) of units connected in parallel to each other. The indoor units (B1 to B3) are connected by communication pipes (LG, LL).

The outdoor unit (A) includes a compressor (1), a four-way switching valve (2), an outdoor heat exchanger (3) as a heat source side heat exchanger, and a liquid side of the outdoor heat exchanger (3). An outdoor motor-operated valve (EV-1) as a heat source-side control valve is provided. Each indoor unit (B1
To B3) are an indoor heat exchanger (4) as a use side heat exchanger, and an indoor electric valve (EV-2) as a use side control valve arranged on the liquid side of the indoor heat exchanger (4). Have. These devices are connected by a refrigerant pipe so that the refrigerant can circulate, and constitute a refrigerant circuit (5) having a closed circuit.

Each of the indoor units (B1 to B3) is provided on each floor in the building and includes an upper floor indoor unit (B1), a middle floor indoor unit (B2), and a lower floor indoor unit (B3). . That is, these indoor units (B1 to B3) have different arrangement height positions.

The four-way switching valve (2) can switch the connection state of each heat exchanger (3, 4) to the discharge side and the suction side of the compressor (1). That is, when the four-way switching valve (2) is switched to the solid line side in the figure, the discharge side of the compressor (1) is connected to the outdoor heat exchanger (3), and the suction side is connected to the indoor heat exchanger (4, 4, 4). ) To allow indoor cooling operation. On the other hand, when the four-way switching valve (2) is
The discharge side of (1) is connected to the indoor heat exchangers (4, 4, 4), and the suction side is connected to the outdoor heat exchanger (3), thereby enabling indoor heating operation.

A plurality of sensors are arranged in the apparatus. In FIG. 1, (Thr) is a room temperature sensor for detecting each indoor temperature, and (Thr1) and (Thr2) are the refrigerant temperatures in the liquid side and gas side pipes of each indoor heat exchanger (4, 4, 4). Indoor liquid temperature sensor and indoor gas temperature sensor to detect, (Tho) is an outdoor heat exchanger
(Tho1) is an outdoor liquid temperature sensor that is disposed at the air inlet of (3) and detects the temperature of the refrigerant in the liquid-side pipe of the outdoor heat exchanger (3). .
(PH) is disposed in the discharge pipe of the compressor (1) and detects a refrigerant pressure discharged from the high pressure sensor. (PL) is disposed in the suction pipe of the compressor (1) and detects low pressure. It is a sensor.

A controller (1) for controlling each device of the present apparatus
0), a detection signal of each of the sensors (Thr to Tho1, PH, PL) is input. The controller (10) controls each device based on these detection signals (compressor ( 1) The capacity control and the opening control of the electric valves (EV-1, EV-2) are performed.

The controller (10) includes an indoor electric valve (EV-
(2) EV-side control means (11) for adjusting the degree of opening of EV-2,
Heat source side control means (12) for adjusting the degree of opening of the outdoor electric valve (EV-1)
And The use side control means (11) keeps the degree of superheat on the outlet side of the indoor heat exchanger (4, 4, 4) constant during the cooling operation, and the indoor heat exchanger (4, 4, 4) during the heating operation. The indoor electric valve (EV-
2, EV-2, EV-2). The heat source side control means (12) keeps the degree of supercooling at the outlet side of the outdoor heat exchanger (3) constant during the cooling operation, and reduces the degree of superheat at the outlet side of the outdoor heat exchanger (3) during the heating operation. The opening degree of the outdoor electric valve (EV-1) is adjusted so as to be kept constant. The degrees of superheat and supercool are calculated based on output signals from the pressure sensors (PH, PL) and the temperature sensors (Thr1 to Tho1). Further, the degree of superheating and the degree of supercooling may be calculated based on a difference between a saturation temperature and an outlet-side temperature in each of the heat exchangers (3, 4).

As a feature of this embodiment, the controller (10)
Indicates the electric valve (EV-2, EV-2) according to the opening of the electric valve (EV-1).
A limiting means (13) for limiting the upper limit of the opening of the EV-2, EV-2) is provided. Outdoor heat exchanger for low outdoor air heating operation
In order to maintain the degree of superheat at the outlet side of the outdoor heat exchanger (3), the heat source side control means (12) is required to open the outdoor motor-operated valve (EV-1) to maintain the degree of superheat at the outdoor heat exchanger (3). Smaller. In addition, since the degree of supercooling at the outlet side of the indoor heat exchanger (4, 4, 4) increases due to the reduction in the amount of circulating refrigerant, the use side control means (11) uses the indoor electric valve (EV-2, EV- 2, Increase the opening of EV-2). In such a situation, the restricting means (13) controls the indoor motor-operated valve (EV-2, EV-2, EV-2) which can be adjusted by the use side control means (11).
The upper limit of the opening is limited to a predetermined opening or less.
Thereby, a pressure difference between the inlet side and the outlet side of the indoor heat exchanger (4, 4, 4) is ensured.

More specifically, FIG. 2 (the horizontal axis represents the outdoor electric valve (EV-
1), the vertical axis indicates the upper limit of the opening of the indoor motor-operated valve (EV-2)), and the opening of the outdoor motor-operated valve (EV-1) is equal to the predetermined value (I) (for example, No limit is imposed on the upper limit of the degree of opening of the indoor electric valve (EV-2) until it drops to 40%). That is, the indoor electric valve (EV-
The upper limit value of the opening degree of 2) is set to the fully opened state (α) of the indoor electric valve (EV-2).
(Opening 100%).

The opening degree of the outdoor motor-operated valve (EV-1) is equal to the predetermined value (I).
When it drops to below, the upper limit of the degree of opening of the indoor electric valve (EV-2) is limited. This restriction includes the operation of the indoor motor-operated valve (EV- 1) until the opening of the outdoor motor-operated valve (EV- 1) decreases from the predetermined value (I) to reach another predetermined value (II) (for example, the opening degree 15%). The upper limit of the opening of the indoor motor-operated valve (EV-2) is gradually reduced when the opening of the outdoor motor-operated valve (EV-1) is at the predetermined value (II).
(β) (for example, the opening degree is 80%). As described above, in a situation where the opening degree of the outdoor electric valve (EV-1) is small, the opening degree of the indoor electric valve (EV-2) should be as large as possible to secure the refrigerant circulation amount, and the indoor heat exchange should be performed. Although it is preferable to maintain a constant degree of supercooling at the outlet side of the heater (4, 4, 4), in the present embodiment, when the opening degree of the outdoor electric valve (EV-1) decreases to a predetermined value or less, By limiting the upper limit of the degree of opening of the indoor electric valve (EV-2) as described above, the indoor heat exchanger (4, 4, 4) while sacrificing the refrigerant circulation amount in the refrigerant circuit (5) to some extent The pressure difference between the inlet side and the outlet side is ensured, and the refrigerant is circulated through the indoor heat exchangers (4, 4, 4) to ensure the capacity of the indoor units (B1 to B3). .

-Air-conditioning operation- Next, the air-conditioning operation of the air conditioner configured as described above will be described.

During the cooling operation, the four-way switching valve (2) switches to the solid line side, and the high-pressure gas refrigerant discharged from the compressor (1) exchanges heat with the outside air in the outdoor heat exchanger (3) to condense. And
After reducing the pressure through the outdoor electric valve (EV-1) and indoor electric valve (EV-2, EV-2, EV-2), heat exchange with indoor air is performed by the indoor heat exchanger (4, 4, 4). To return to the compressor (1). This cools the room air and cools the room. At this time, each control means (1
(1,12) maintain the degree of supercooling at the outlet side of the outdoor heat exchanger (3) constant and maintain the degree of superheat at the outlet side of the indoor heat exchanger (4,4,4) constant. The opening of each motor-operated valve (EV-1, EV-2) is adjusted.

On the other hand, during the heating operation, the four-way switching valve (2) switches to the broken line side, and the high-pressure gas refrigerant discharged from the compressor (1) passes through the indoor heat exchangers (4, 4, 4) to the room. After condensing by performing heat exchange with air and reducing the pressure through the indoor electric valves (EV-2, EV-2, EV-2) and the outdoor electric valve (EV-1), the outdoor air exchanger (3) And heat exchange to return to the compressor (1). This heats the room air to heat the room. At this time, the respective control means (11, 12) maintain the degree of supercooling at the outlet side of each indoor heat exchanger (4, 4, 4) at a constant level, and at the same time superheat the outlet side of the outdoor heat exchanger (3). Each electric valve (EV-1, EV-2) to keep the degree constant
Is adjusted.

If the outside air temperature is extremely low during such a heating operation, the evaporation capacity of the outdoor heat exchanger (3) will be reduced, and the control means (11, 1
Due to 2), the opening degree of the outdoor motor-operated valve (EV-1) decreases and the opening degree of the indoor motor-operated valves (EV-2, EV-2, EV-2) increases. And
When the opening of the outdoor motor-operated valve (EV-1) decreases to the predetermined value (I), the limiting means (13) sets a limit on the upper limit of the opening of the indoor motor-operated valve (EV-2). That is, the upper limit of the opening degree of the indoor electric valve (EV-2) is gradually increased until the opening degree of the outdoor electric valve (EV-1) decreases from the predetermined value (I) and reaches another predetermined value (II). To decrease. By limiting the upper limit of the degree of opening of the indoor motor-operated valve (EV-2), a sufficient pressure difference between the inlet side and the outlet side of the indoor heat exchanger (4, 4, 4) can be secured. A good refrigerant flow state in the indoor heat exchangers (4, 4, 4) is obtained.

In particular, when the indoor units (B1 to B3) are installed at different heights by being applied to an air conditioner for building air conditioning as in the present embodiment, the indoor motor-operated valves (4, 4,
When the opening degree of (4) increases, the liquid refrigerant accumulates in the indoor heat exchanger (4) of the indoor unit (B3) on the lower floor, and the indoor heat exchanger (4) can hardly exercise its capacity. However, according to the present embodiment, such a situation can be prevented from occurring, the refrigerant can flow evenly through the indoor electric valves (4, 4, 4), and the indoor unit (B3 ) Can obtain sufficient heating capacity.

In this embodiment, a case has been described in which the present invention is applied to an air conditioner for building air conditioning. However, the present invention is not limited to this, and can be applied to other refrigeration devices.

[0035]

As described above, according to the present invention, the following effects are exhibited. According to the first aspect of the present invention, during the heat dissipation operation in which the refrigerant condenses in the use side heat exchangers (4, 4, 4) and the refrigerant evaporates in the heat source side heat exchanger (3), the use side heat exchanger (4 ,
(4) Each control valve (EV-2) on the user side and the heat source side so as to maintain the degree of supercooling on the outlet side constant and maintain the degree of superheating on the heat source side heat exchanger (3) outlet side constant. , EV-1), the evaporating capacity of the heat source side heat exchanger (3) decreases, and the opening of the heat source side control valve (EV-1) decreases. When the opening degree of the usage-side control valve (EV-2) becomes large, the upper limit of the opening degree of the usage-side control valve (EV-2) is limited and the usage-side heat exchanger (4, 4, 4 ), A sufficient pressure difference between the inlet side and the outlet side can be secured. For this reason, it is possible to obtain a good refrigerant flow state in each of the use-side heat exchangers (4, 4, 4), to allow the refrigerant to flow evenly to each, and to stabilize the refrigerant circulation operation. it can.

According to the second aspect of the invention, the arrangement heights of the use side heat exchangers (4, 4, 4) are different from each other. In such a configuration, the use side control valve (EV-2, EV-2, E
In the situation where the opening degree of V-2) is large and the pressure difference between the inlet side and outlet side of each use side heat exchanger (4,4,4) is small, the installation height position is low. Although the liquid refrigerant tends to accumulate in the use-side heat exchanger (4), in the present invention, the use-side control valve (E
(V-2, EV-2, EV-2) limit the upper limit of the degree of opening to ensure a pressure difference between the inlet and outlet sides of each user-side heat exchanger (4, 4, 4) Use-side heat exchanger with a low installation height
The refrigerant can be sufficiently circulated through (4).
For this reason, each use side heat exchanger (4, 4, 4) exerts its capacity equally, and the reliability of the device can be improved.

According to the third aspect of the present invention, the heat source side control means is provided.
When the opening of the heat source side control valve (EV-1) becomes equal to or less than the predetermined opening due to (12), the use side control valve becomes smaller as the opening becomes smaller.
The upper limit of the opening of (EV-2, EV-2, EV-2) is gradually reduced. If the upper limit of the opening of the usage-side control valve (EV-2, EV-2, EV-2) is rapidly reduced, the opening becomes smaller than necessary and the usage-side control valve (EV-2 , EV-2, EV-2) Although the degree of supercooling on the outlet side may be too large, as described above, by gradually lowering the opening upper limit, the behavior of the refrigerant circulation operation The effect according to the first aspect of the present invention can be obtained without causing the above.

In the invention described in claim 4, the present invention is applied to an air conditioner. Therefore, the apparatus to which the present invention is applied can be embodied, and the practicality can be improved. In addition, since the refrigerant can flow evenly to the indoor heat exchangers (4, 4, 4) disposed in each room, it is possible to heat each room satisfactorily and to maintain a stable air-conditioning state. Obtainable.

[Brief description of the drawings]

FIG. 1 is a refrigerant piping system diagram according to an embodiment.

FIG. 2 is a diagram showing a relationship between an outdoor electric valve opening and an upper limit value of an indoor electric valve opening.

[Explanation of symbols]

 (1) Compressor (3) Outdoor heat exchanger (heat source side heat exchanger) (4) Indoor heat exchanger (use side heat exchanger) (5) Refrigerant circuit (11) Use side control means (12) Heat source side Control means (13) Limiting means (EV-1) Outdoor electric valve (heat source side control valve) (EV-2) Indoor electric valve (use side control valve)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Ikui Ishii 1304 Kanaokacho, Sakai City, Osaka Daikin Industries, Ltd. Inside the Sakai Seisakusho Kanaoka Plant (72) Inventor Seiji Sakai 1304 Kanaokacho, Sakai City, Osaka Daikin Industries, Ltd. Inside the Sakai Plant Kanaoka Plant (72) Inventor Makoto Furuta 1304 Kanaokacho, Sakai City, Osaka Daikin Industries Inside the Sakai Plant Kanaoka Plant

Claims (4)

[Claims] A compressor (1), a plurality of use-side heat exchangers (4, 4, 4) connected in parallel to each other, and a use-side control valve (EV-2, EV-2, EV -2), the heat source side control valve (EV-
1), a heat source side heat exchanger (3) is provided with a refrigerant circuit (5) connected by refrigerant piping, and a use side heat exchanger (4, 4,
During the heat dissipation operation in which the refrigerant condenses in 4) and the refrigerant evaporates in the heat source side heat exchanger (3), the degree of supercooling of the refrigerant at the outlet side of the use side heat exchanger (4, 4, 4) is kept constant. Use side control valve (EV-2, EV-
(2) The use side control means (11) for adjusting the opening of the heat source side heat exchanger (3) and the heat source side control valve (EV-1) so as to keep the refrigerant superheat degree at the outlet side of the heat source side heat exchanger (3) constant. Heat source side control means for adjusting the opening degree
In the refrigerating apparatus provided with (12), during the heat dissipation operation, the evaporation capacity of the heat source side heat exchanger (3) is reduced, and the heat source side control valve (EV-1) is opened by the heat source side control means (12). When the degree becomes equal to or less than the predetermined opening, the upper limit of the opening of the use-side control valves (EV-2, EV-2, EV-2) which can be adjusted by the use-side control means (11) is set to the predetermined value or less. Restrict and use side heat exchanger (4,4,4)
A refrigerating apparatus comprising a limiting means (13) for securing a pressure difference between an inlet side and an outlet side of the refrigeration system. 2. The refrigeration system according to claim 1, wherein the use side heat exchangers (4, 4, 4) are arranged at different heights from each other. 3. The refrigeration apparatus according to claim 1, wherein the restricting means (13) is provided when the opening degree of the heat source side control valve (EV-1) becomes equal to or less than a predetermined opening degree by the heat source side control means (12). And a refrigeration system characterized by gradually decreasing the upper limit of the opening of the usage-side control valves (EV-2, EV-2, EV-2) as the opening decreases. 4. The refrigeration apparatus according to claim 1, wherein the use side heat exchanger is an indoor heat exchanger disposed in an air conditioning room.
(4, 4, 4), wherein the heat source side heat exchanger is an outdoor heat exchanger (3) disposed outdoors.