JPH09257323A - Refrigerant circulation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lack of oil in a freezer of a compressor from being kept for a long period of time and enable its performance to be kept high even in the case that an indoor device is installed relatively above an outdoor device. SOLUTION: This refrigerant circulation system is comprised of a compressor 6 in which oil 7 of a freezer having a lower specific weight than that of liquid refrigerant and showing a low soluble characteristic to liquid refrigerant under a condition of condensing pressure and condensing temperature is applied, either gaseous refrigerant or gaseous refrigerant containing partially liquid refrigerant is sucked and discharged as high pressurized gaseous refrigerant; a condensor 3 for condensing high pressure gaseous refrigerant discharged from the compressor 6; a throat mechanism 13 for reducing pressure of condensed liquid refrigerant or liquid refrigerant partially containing gaseous refrigerant; and an evaporator 4 for evaporating liquid refrigerant or gas-liquid two-phase refrigerant flowed from the throat mechanism 13. A liquid-side connecting pipe 12 where a down flow is formed is connected between the condensor 3 and the evaporator 4 so as to constitute a refrigerant circulation system and the throat mechanism 13 is arranged at an upstream side of the liquid side connecting pipe 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant circulation system using a refrigerating machine oil having a smaller specific weight than a liquid refrigerant and a low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions.

[0002]

2. Description of the Related Art A conventional refrigerating machine oil having a specific weight smaller than that of a liquid refrigerant and a low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used as a gas refrigerant or a gas refrigerant partially containing the liquid refrigerant. A compressor that sucks in and discharges as a high-pressure gas refrigerant, a throttle mechanism that decompresses the liquid refrigerant or a liquid refrigerant that partially contains the gas refrigerant, and decompresses the liquid refrigerant that includes the high-pressure gas refrigerant that is discharged from the compressor. An invention relating to a refrigerant circulation system including a throttle mechanism for controlling a high-pressure gas refrigerant discharged from the compressor, and an evaporator for evaporating a liquid refrigerant or a gas-liquid two-phase refrigerant discharged from the throttle mechanism, For example, it is disclosed in JP-A-5-157379 or JP-A-7-208819.

A conventional technique will be described below with reference to FIG. FIG. 6 shows an example of a refrigerant circulation system applied to a separate heat pump type air conditioner used for air conditioning of a medium-scale building for a store, for example. In FIG.
1 is an indoor unit provided with an indoor heat exchanger 3 for exchanging heat with indoor air, 2 is an outdoor heat exchanger 4 for exchanging heat with outdoor air, a compressor 6 for compressing a refrigerant, a refrigerant The outdoor unit is provided with a four-way valve 8 for switching the circulation direction and an outdoor throttle mechanism 5 for adjusting the circulation amount of the refrigerant.

Further, the indoor unit 1 and the outdoor unit 2 constitute a refrigerant circulation system which is connected by a gas side connecting pipe 11 and a liquid side connecting pipe 12 in order to circulate the refrigerant to each. Here, the refrigerating machine oil 7 is stored at the bottom of the compressor 6 in order to ensure the lubrication of the sliding part of the compressor 6 and the sealing property of the compression chamber and the four-way valve 8 inside the compressor 6. Further, hydrofluorocarbon having an ozone depletion coefficient of zero is used as the refrigerant, and the refrigerating machine oil 7 uses alkylbenzene, which has excellent chemical stability and lubricity, but has low solubility with the liquid refrigerant.

Next, in the above-mentioned conventional example, when the indoor unit 1 is installed relatively above the outdoor unit 2, which is a system arrangement that is generally widely used, the refrigerant and the refrigerating machine oil at the time of starting the heating operation mode are The behavior will be described. If the system is stopped and left for a long time,
Refrigerant accumulates in the compressor 6 in which the refrigerating machine oil 7 that is weak but has solubility is stored. Then, the refrigerating machine oil 7 having a smaller specific weight with respect to the liquid refrigerant floats above the accumulated liquid refrigerant.

[0006] Here, when the liquid refrigerant exceeding the internal capacity of the compressor 6 is accumulated, the floating refrigerating machine oil 7 remains in the compressor 6.
Will flow out into the refrigerant circuit. When the system is started in such a state, the refrigerating machine oil 7 flowing out into the circuit together with the compressed gas refrigerant is connected to the gas side connecting pipe 11
Is discharged to the indoor heat exchanger 3 via. The refrigerant is condensed inside the indoor heat exchanger 3, and the refrigerant is completely liquefied at the outlet of the indoor heat exchanger 3 so that the flow velocity in the pipe is significantly reduced.
Refrigerating machine oil 7 that exceeds the amount dissolved in the liquid refrigerant stays in the liquid side connection pipe 12.

[0007]

In the above-mentioned prior art, when refrigerating machine oil exceeding the amount of dissolved refrigerant and refrigerating machine oil flows out from the compressor into the refrigerant circuit when the refrigerant circulation system is started up, the refrigerant is liquified. Between the outlet of the condenser flowing in this state and the throttle mechanism, the refrigerating machine oil in excess of the dissolved amount flows as oil droplet particles in the liquid refrigerant. Here, when there is a flow path where a downward flow is formed between the condenser and the throttle mechanism, the specific weight of the refrigerating machine oil is smaller than the specific weight of the liquid refrigerant. As shown in the figure, the oil droplets generate buoyancy against the flow direction.

When the flow rate of the liquid refrigerant is high, the oil droplets overcome the buoyancy and flow with the liquid refrigerant, but when the flow rate of the liquid refrigerant is low, the oil droplets form a downward flow due to the buoyancy. Stay in the upstream part of the flow path. Even in this state, the amount of refrigerating machine oil dissolved in the liquid refrigerant is
Although it circulates through the refrigerant circuit with the refrigerant and returns to the compressor, it takes time for all the refrigerating machine oil that has flowed out to return to the compressor. Therefore, until the refrigerating machine oil is completely returned to the compressor, the compressor will be operated in a state where the refrigerating machine oil is low, reducing the reliability of sliding parts such as bearings in the compressor and sealing the oil seal part. There is a possibility that the performance may be deteriorated due to the deterioration of the sex.

The present invention has been made to solve the above problems. Even when the indoor unit is installed above the outdoor unit, the shortage of refrigerating machine oil in the compressor is prolonged. It is an object of the present invention to obtain a refrigerant circulation system capable of maintaining high performance without doing so.

[0010]

A refrigerant circulation system according to the present invention uses a refrigerating machine oil having a smaller specific weight than a liquid refrigerant and a low solubility in the liquid refrigerant under the conditions of a condensation pressure and a condensation temperature. A compressor that sucks a gas refrigerant containing a liquid refrigerant into a portion and discharges it as a high-pressure gas refrigerant, a condenser that condenses the high-pressure gas refrigerant discharged from the compressor, and a liquid refrigerant condensed by the condenser. Alternatively, a throttle mechanism for decompressing a liquid refrigerant containing a gas refrigerant in a part, and an evaporator that evaporates the liquid refrigerant or the gas-liquid two-phase refrigerant from the throttle mechanism to the compressor, the condenser and the A refrigerant circulation system is configured by connecting a flow path in which a downward flow is formed between the evaporator and the throttle mechanism to the upstream part or both the upstream part and the downstream part of the flow path in which the downward flow is formed. It is provided.

Further, refrigerating machine oil having a smaller specific weight than the liquid refrigerant and low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used, and the separated indoor unit and outdoor unit are connected to the gas side connecting pipe and the liquid side. A refrigerant circulation system that forms a separate type heat pump air conditioner by connecting with a connecting pipe is provided, and a throttle mechanism is provided on the upstream side or both the upstream side and the downstream side of the liquid side connecting pipe.

Further, refrigerating machine oil having a smaller specific weight than the liquid refrigerant and a low solubility in the liquid refrigerant under the conditions of condensing pressure and condensing temperature is used, and the gas refrigerant or a gas refrigerant containing a part of the liquid refrigerant is sucked to a high pressure. A compressor that discharges as a gaseous refrigerant, a condenser that condenses the high-pressure gas refrigerant that is discharged from the compressor, and a liquid refrigerant that is condensed in the condenser or a liquid refrigerant that partially contains a gas refrigerant is decompressed. A throttle mechanism, a control unit that controls the opening of the throttle mechanism so that the refrigerant between the condenser and the throttle mechanism is in a gas-liquid two-phase state, and a liquid refrigerant or gas-liquid two-phase from the throttle mechanism. An evaporator that evaporates a refrigerant to reach the compressor is provided, and a flow path in which a downward flow is formed is connected between the condenser and the evaporator.

Further, a temperature sensor for detecting the temperature between the center of the condenser and the vicinity of the outlet of the condenser is provided, and the controller controls the temperature near the outlet of the condenser based on the detection result of the temperature sensor. When the temperature becomes lower than the central temperature of the condenser, the opening of the throttle mechanism is controlled to be increased.

Further, the control unit controls the opening degree of the throttle mechanism such that the refrigerant between the condenser and the throttle mechanism is in a gas-liquid two-phase state for a predetermined time after the refrigerant circulation system is activated. It is a thing.

Further, refrigerating machine oil having a smaller specific weight than the liquid refrigerant and low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used, and the separated indoor unit and outdoor unit are connected to the gas side connecting pipe and the liquid side. A refrigerant circulation system that forms a separate type heat pump air conditioner by connecting with a connection pipe is formed, and a throttle mechanism provided in the liquid side connection pipe so that the flow velocity of the refrigerant in the liquid side connection pipe becomes faster than usual at system startup. A control unit for controlling the opening is provided.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described with reference to FIG.
It will be described based on. FIG. 1 is an example of a refrigerant circulation system applied to a separate type air conditioner used for air conditioning of a large building such as a building.
Is an indoor unit having an indoor heat exchanger 3 for exchanging heat with the indoor air and an indoor expansion mechanism 13 for adjusting the circulation amount of the refrigerant, and 2 is an outdoor unit for exchanging heat with the outdoor air. The outdoor unit includes a heat exchanger 4, a compressor 6 for compressing the refrigerant, a four-way valve 8 for switching the circulation direction of the refrigerant, and an outdoor throttle mechanism 5 for adjusting the circulation amount of the refrigerant.

Further, the indoor unit 1 and the outdoor unit 2 are connected by a gas side connecting pipe 11 and a liquid side connecting pipe 12 in order to circulate a refrigerant to each of them, and constitute a refrigerant circulating system. Here, the refrigerating machine oil 7 is stored at the bottom of the compressor 6 in order to ensure the lubrication of the sliding part of the compressor 6 and the sealing properties of the compression chamber and the four-way valve 8 inside the compressor 6. There is. Further, hydrofluorocarbon having an ozone depletion coefficient of zero is used as the refrigerant, and the refrigerating machine oil 7 is an alkylbenzene which has excellent chemical stability and lubricity, but has low solubility with the liquid refrigerant.

Next, in the present embodiment, the behaviors of the refrigerant and the refrigerating machine oil when the heating operation mode is started when the indoor unit 1 is installed relatively above the outdoor unit 2 will be described. When the system is stopped and left for a long period of time, the refrigerant accumulates in a liquefied state in the compressor 6 in which the refrigerating machine oil 7 that is weak but has solubility is stored. Here, the refrigerating machine oil 7 having a smaller specific weight than the liquid refrigerant floats above the accumulated liquid refrigerant. When liquid refrigerant that exceeds the internal capacity of the compressor 6 accumulates,
The floating refrigerating machine oil 7 flows out from the compressor 6 into the refrigerant circuit.

When the system is started in such a state, the refrigerating machine oil 7 flowing into the circuit is discharged to the indoor heat exchanger 3 together with the compressed gas refrigerant through the gas side connecting pipe 11. Refrigerant is condensed inside the indoor heat exchanger 3, and the refrigerant is completely liquefied at the outlet of the indoor heat exchanger 3 and the flow velocity in the pipe is significantly reduced. However, as shown in FIG. Since a part of the liquid refrigerant is gasified before the temperature becomes, the in-pipe flow velocity increases in the liquid-side connection pipe 12 that becomes a downward flow, and the refrigerating machine oil 7 flows in the liquid-side connection pipe 12.
Does not stay.

Therefore, even when the indoor unit is installed relatively above the outdoor unit, a shortage of refrigerating machine oil in the compressor does not last for a long time when the refrigerant circulation system is started, and sliding parts such as bearings in the compressor do not exist. It is possible to effectively prevent the deterioration of the performance due to the deterioration of reliability of the oil seal and the deterioration of the sealing property of the oil seal portion, and it is possible to maintain the high performance.

In the above embodiment, the heating operation mode is started up when the indoor unit is installed relatively above the outdoor unit, but in the case of a heat pump type air conditioner, the cooling operation is generally performed. Since the refrigerant circulation is sometimes the reverse of the heating operation, when the outdoor unit is installed relatively above the indoor unit, when the cooling operation mode is started, the indoor expansion mechanism of FIG. The same effect can be obtained by providing the same function as the diaphragm mechanism. In particular, if the throttling mechanism is provided on both sides of the liquid side connecting pipe as in the present embodiment, the present invention can be adapted to the system arrangement according to the user's request.

Embodiment 2 of the Invention Another embodiment of the present invention will be described below with reference to FIG. FIG. 3 shows an example of a system applied to a separate air conditioner for home use. In FIG. 3, reference numeral 1 denotes an indoor unit equipped with an indoor heat exchanger 3 for exchanging heat with indoor air. An indoor heat exchanger central temperature sensor 9 and an indoor heat exchanger outlet temperature sensor 10 are attached to the heat exchanger 3.

Reference numeral 2 denotes an outdoor heat exchanger 4 for exchanging heat with the outdoor air, a compressor 6 for compressing the refrigerant, a four-way valve 8 for switching the circulation direction of the refrigerant, and a circulation amount of the refrigerant. The detection results of the electronically controlled expansion valve that becomes the outdoor side expansion mechanism 5, the indoor heat exchanger central part temperature sensor 9 and the indoor heat exchanger outlet part temperature sensor 10 are input, and the outdoor side expansion valve is based on these detection results. The outdoor unit includes a control unit 14 that controls the opening degree of the mechanism 5.

Further, the indoor unit 1 and the outdoor unit 2 are connected by a gas side connecting pipe 11 and a liquid side connecting pipe 12 in order to circulate a refrigerant to each of them, and constitute a refrigerant circulating system. Here, the refrigerating machine oil 7 is stored at the bottom of the compressor 6 in order to ensure the lubrication of the sliding part of the compressor 6 and the sealing properties of the compression chamber and the four-way valve 8 inside the compressor 6. There is. Further, hydrofluorocarbon having an ozone depletion coefficient of zero is used as the refrigerant, and the refrigerating machine oil 7 is an alkylbenzene which has excellent chemical stability and lubricity, but has low solubility with the liquid refrigerant.

Next, in this embodiment, when the indoor unit 1 is installed relatively above the outdoor unit 2, the behavior of the refrigerant and the refrigerating machine oil at the start of the heating operation mode and the throttle according to the present invention. A method of controlling the opening degree of the mechanism 5 will be described. When the system is stopped and left for a long period of time, the refrigerant accumulates in a liquefied state in the compressor 6 in which the refrigerating machine oil 7 that is weak but has solubility is stored.
Here, the refrigerating machine oil 7 having a smaller specific weight than the liquid refrigerant floats above the accumulated liquid refrigerant.

Here, when the liquid refrigerant that exceeds the internal capacity of the compressor 6 is accumulated, the floating refrigerating machine oil 7 is removed from the compressor 6.
Out of the refrigerant circuit. When the system is activated in such a state, the refrigerating machine oil 7 flowing out into the circuit is discharged to the indoor heat exchanger 3 together with the compressed gas refrigerant via the gas side connecting pipe 11. The refrigerant is condensed inside the indoor heat exchanger 3, and the refrigerant is completely liquefied at the outlet of the indoor heat exchanger 3 and the flow velocity in the pipe is significantly reduced.

In the control method of the outdoor throttling mechanism 5 of the present invention, when there is a large outflow of the refrigerating machine oil 7 from the compressor 6 immediately after the system is started in this way, the control unit 14 keeps the indoor heat exchanger for a predetermined time. The opening of the throttling mechanism is controlled so that the difference between the temperature detected by the intermediate temperature sensor 9 and the temperature detected by the indoor heat exchanger outlet temperature sensor 10 becomes a certain value or less. When the refrigerating machine oil returns to the compressor, the control unit 14 ends the opening of the outdoor throttle mechanism 5 so as to move the liquid-side refrigerant pipe 12 in a flow state during normal operation. Control.

The predetermined time for performing such control is, for example, the time during which the refrigerant circulation system is stopped, and if the stop time exceeds a certain lower limit time according to the stop time, the above-described time is set. The refrigerant transfer time is set by a simple flow control, and if the stop time is long, this refrigerant transfer time is lengthened, or if the stop time exceeds a certain lower limit time, the above-mentioned refrigerant transfer time is set to a certain time. You can do this. According to the former configuration, since the refrigerant movement time by the flow control is performed only for the necessary time, there is no waste, and in the latter case, the control is simple and therefore the cost can be reduced.

The state of the refrigerant when the opening degree of the electronically controlled expansion valve is controlled will be described with reference to FIG. Assuming that the temperature detected by the indoor heat exchanger central temperature sensor 9 is T2 and the temperature detected by the indoor heat exchanger outlet temperature sensor 10 is T1, the indoor air temperature is low immediately after the system is started. Therefore, the amount of heat exchange in the indoor heat exchanger 3 increases, and the refrigerant near the outlet of the indoor heat exchanger 3 becomes a supercooled liquid state, and T1
<T2.

In this state, the refrigerant in the liquid side connecting pipe 12 is in a liquid state, and the flow velocity is remarkably reduced. Therefore, the control unit 14 controls the temperature T1 to T2 (T1≈T2). By controlling the opening degree of the expansion valve 5 to be large, the flow velocity in the liquid side connection pipe 12 can be increased and the refrigerating machine oil retention phenomenon can be prevented. If such a method is used, as in the first embodiment, the liquid side connection pipe 12
The same effect as that of the first embodiment can be obtained without complicating the configuration of the refrigerant circulation system in which the throttling mechanism is provided on the upstream side.

FIG. 5 is a diagram showing a time transition of the amount of refrigerating machine oil inside the compressor at the time of system startup after being left for a long time in the present invention and the conventional example. In the conventional example as well, since the refrigerating machine oil 7 has a weak solubility, the refrigerating machine oil 7 once taken out into the refrigerant circuit may return to the compressor 6 with time as much as it is dissolved in the circulating refrigerant. However, it takes a long time to recover the amount of refrigerating machine oil that should be constantly stored. On the other hand, according to the configuration and control of the present invention, the refrigerating machine oil 7 does not stay in the liquid side connecting pipe 12, and the refrigerating machine oil amount is recovered in a short time.

[0032]

As described above, according to the present invention, a refrigerating machine oil having a smaller specific weight than a liquid refrigerant and a low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used, and the liquid refrigerant is partially or partially liquid. A compressor that sucks a gas refrigerant containing a refrigerant and discharges it as a high-pressure gas refrigerant, a condenser that condenses the high-pressure gas refrigerant discharged from the compressor, and a liquid refrigerant or a part thereof condensed by the condenser. A throttle mechanism for depressurizing a liquid refrigerant containing a gas refrigerant, and an evaporator that evaporates a liquid refrigerant or a gas-liquid two-phase refrigerant from the throttle mechanism to the compressor, the condenser and the evaporator. A refrigerant circulation system is configured by connecting flow paths in which a descending flow is formed between
Since the throttling mechanism is provided in both the upstream portion or the upstream portion and the downstream portion of the flow path in which the downstream flow is formed, refrigerating machine oil that exceeds the amount of refrigerant and refrigerating machine oil dissolved, such as when the refrigerant circulation system is started up. Even if oil leaks from the compressor into the refrigerant circuit, oil is returned to the compressor in a short time, the reliability of the sliding parts such as the bearings in the compressor is high, and the performance due to the deterioration of the oil seal sealing performance. This has the effect of obtaining a system without a decrease in power consumption.

Further, refrigerating machine oil having a smaller specific weight than the liquid refrigerant and a low solubility in the liquid refrigerant under the conditions of condensation pressure and condensation temperature is used, and the separated indoor unit and outdoor unit are connected to the gas side connecting pipe and the liquid side. A refrigerant circulation system that forms a separate type heat pump air conditioner by connecting with a connecting pipe is provided, and a throttle mechanism is provided at both the upstream part or both the upstream part and the downstream part of the liquid side connecting pipe, so that the refrigerant is a refrigerant circulating system. Since it moves at a high flow rate inside the compressor, even when refrigerating machine oil that exceeds the dissolved amount of the refrigerating machine and refrigerating machine oil flows out from the compressor into the refrigerant circuit, such as when starting up the refrigerant circulation system, the oil is returned to the compressor. It is possible to obtain a system that is performed in a short time, has high reliability of sliding parts such as bearings in the compressor, and has no performance deterioration due to deterioration of sealing performance of the oil seal part.

Further, a refrigerating machine oil having a smaller specific weight than the liquid refrigerant and a low solubility in the liquid refrigerant under the conditions of the condensation pressure and the condensation temperature is used, and the gas refrigerant or a gas refrigerant containing a part of the liquid refrigerant is sucked to a high pressure. A compressor that discharges as a gaseous refrigerant, a condenser that condenses the high-pressure gas refrigerant that is discharged from the compressor, and a liquid refrigerant that is condensed in the condenser or a liquid refrigerant that partially contains a gas refrigerant is decompressed. A throttle mechanism, a control unit that controls the opening of the throttle mechanism so that the refrigerant between the condenser and the throttle mechanism is in a gas-liquid two-phase state, and a liquid refrigerant or gas-liquid two-phase from the throttle mechanism. An evaporator that evaporates a refrigerant to the compressor is provided, and a flow path in which a downward flow is formed is connected between the condenser and the evaporator, so that the structure of the refrigerant circulation system is complicated. Refrigerant circulation without increasing the size Even if the refrigerating machine oil that exceeds the melting amount of the refrigerating machine and refrigerating machine oil flows out from the compressor into the refrigerant circuit when the system is started up, oil is returned to the compressor in a short time, and bearings inside the compressor are used. The reliability of the sliding part of
It is possible to obtain the system in which the performance is not deteriorated due to the deterioration of the sealing property of the oil seal portion.

Further, a temperature sensor for detecting the temperature between the center of the condenser and the vicinity of the outlet of the condenser is provided, and the controller controls the temperature near the outlet of the condenser based on the detection result of the temperature sensor. When the temperature becomes lower than the temperature in the center of the condenser, the aperture of the throttle mechanism is controlled to be increased.Therefore, the aperture of the throttle mechanism is unnecessarily increased to reduce the system performance unnecessarily. Even when refrigerating machine oil that exceeds the melting amount of refrigerating machine and refrigerating machine oil flows out from the compressor into the refrigerant circuit when the refrigerant circulation system is started up, the oil is returned to the compressor in a short time, It is possible to obtain a system in which the reliability of the sliding portion such as the bearing is high and the performance is not deteriorated due to the deterioration of the sealability of the oil seal portion.

The control unit controls the opening degree of the throttle mechanism for a predetermined time after the refrigerant circulation system is activated so that the refrigerant between the condenser and the throttle mechanism is in a gas-liquid two-phase state. Therefore, after returning the refrigerating machine oil that circulates at startup for a short time, it operates as a refrigeration circulation system in the hall, so it is possible to bring out the system performance sufficiently. can get.

Further, refrigerating machine oil having a smaller specific weight than the liquid refrigerant and low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used, and the separated indoor unit and outdoor unit are connected to the gas side connecting pipe and the liquid side. A refrigerant circulation system that forms a separate type heat pump air conditioner by connecting with a connection pipe is formed, and a throttle mechanism provided in the liquid side connection pipe so that the flow velocity of the refrigerant in the liquid side connection pipe becomes faster than usual at system startup. Since the control unit for controlling the opening degree is provided, the refrigerant moves at a high speed in the refrigerant circulation system, so that the refrigerant circulation system can be started up at a high speed without complicating the structure of the refrigerant circulation system. Even if refrigerating machine oil that exceeds the melting amount of refrigerating machine oil flows into the refrigerant circuit from the compressor, oil is returned to the compressor in a short time, and the reliability of sliding parts such as bearings in the compressor is improved. High, there is an effect that no drop in performance due to the seal deterioration of the oil seal portion system is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigerant circulation system according to a first embodiment of the present invention.

FIG. 2 is a state diagram of a circulating refrigerant of the refrigerant circulation system according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a refrigerant circulation system according to a second embodiment of the present invention.

FIG. 4 is a state diagram of circulating refrigerant in the refrigerant circulating system according to Embodiment 2 of the present invention.

FIG. 5 is a time transition characteristic diagram of the amount of refrigerating machine oil inside the compressor according to the conventional example and the embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional refrigerant circulation system.

FIG. 7 is a schematic diagram of the flow states of the liquid refrigerant and the refrigerating machine oil in the liquid side connection pipe (downflow) in the conventional refrigerant circulation system.

[Explanation of symbols]

1 indoor unit, 2 outdoor unit, 3 indoor heat exchanger, 4
Outdoor heat exchanger, 5 outdoor expansion mechanism (electronic expansion valve), 6 compressor, 7 refrigerator oil, 8 four-way valve,
9 indoor heat exchanger central part temperature sensor, 10 indoor heat exchanger outlet temperature sensor, 11 gas side connection pipe, 12 liquid side connection pipe, 13 indoor side throttling mechanism,
14 Control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takami Hozuki 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd.

Claims (6)

[Claims] 1. A refrigerating machine oil having a smaller specific weight than a liquid refrigerant and a low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used, and a gas refrigerant or a gas refrigerant partially containing the liquid refrigerant is sucked to a high pressure. A compressor for discharging as a gaseous refrigerant,
A condenser for condensing the high-pressure gas refrigerant discharged from the compressor, a throttle mechanism for depressurizing the liquid refrigerant condensed in the condenser or a liquid refrigerant containing a gas refrigerant in a part, and a liquid from the throttle mechanism. An evaporator for evaporating a refrigerant or a gas-liquid two-phase refrigerant to reach the compressor is provided, and a refrigerant circulation system is configured by connecting a flow path in which a downward flow is formed between the condenser and the evaporator. However, the refrigerant circulation system is characterized in that the throttling mechanism is provided in the upstream portion or both the upstream portion and the downstream portion of the flow path in which the downward flow is formed. 2. A refrigerating machine oil having a smaller specific weight than a liquid refrigerant and a low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used, and the separated indoor unit and outdoor unit are connected to a gas side connecting pipe and a liquid side. Refrigerant circulation characterized in that a refrigerant circulation system that constitutes a separate heat pump air conditioner is connected by connecting pipes, and a throttling mechanism is provided in the upstream part or both the upstream part and the downstream part of the liquid side connecting pipe. system. 3. A refrigerating machine oil, which has a smaller specific weight than a liquid refrigerant and has a low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions, is used to suck a gas refrigerant or a gas refrigerant containing a part of the liquid refrigerant to obtain a high pressure. A compressor for discharging as a gaseous refrigerant,
A condenser for condensing the high-pressure gas refrigerant discharged from the compressor, a throttle mechanism for depressurizing the liquid refrigerant condensed in the condenser or a liquid refrigerant containing a gas refrigerant in a part, the condenser and the throttle. A control unit that controls the opening degree of the throttle mechanism so that the refrigerant between the mechanism and the mechanism is in a gas-liquid two-phase state, and the liquid refrigerant or the gas-liquid two-phase refrigerant from the throttle mechanism is evaporated and reaches the compressor. A refrigerant circulation system comprising an evaporator, and a flow path in which a downward flow is formed is connected between the condenser and the evaporator. 4. A temperature sensor for detecting the temperature near the center of the condenser and the temperature near the outlet of the condenser is provided, and the controller controls the temperature near the outlet of the condenser based on the detection result of the temperature sensor. The refrigerant circulation system according to claim 3, wherein when the temperature becomes lower than the temperature in the vicinity of the center of the condenser, the opening of the throttle mechanism is controlled to be increased. 5. The control unit controls the opening of the throttle mechanism such that the refrigerant between the condenser and the throttle mechanism is in a gas-liquid two-phase state for a predetermined time after the refrigerant circulation system is activated. The refrigerant circulation system according to claim 3 or 4, characterized in that. 6. A refrigerating machine oil having a smaller specific weight than a liquid refrigerant and a low solubility in the liquid refrigerant under condensing pressure and condensing temperature conditions is used, and the separated indoor unit and outdoor unit are connected to a gas side connecting pipe and a liquid side. A refrigerant circulation system that forms a separate type heat pump air conditioner by connecting with a connection pipe is formed, and a throttle mechanism provided in the liquid side connection pipe so that the flow velocity of the refrigerant in the liquid side connection pipe becomes faster than usual at system startup. A refrigerant circulation system comprising a control unit for controlling an opening degree.