WO2000049346A1

WO2000049346A1 - Refrigerant supercooling circuit

Info

Publication number: WO2000049346A1
Application number: PCT/JP1999/004326
Authority: WO
Inventors: Jirou Fukudome; Ken-Ichi Minami; Masaki Inoue; Takeo Imura; Yoshikazu Oota; Kazutoshi Inayoshi; Keiji Sugimori
Original assignee: Yanmar Diesel Engine Co., Ltd.
Priority date: 1999-02-17
Filing date: 1999-08-09
Publication date: 2000-08-24
Also published as: EP1162414A1; EP1162414A4; ATE329213T1; PT1162414E; ES2265187T3; EP1162414B1; DE69931816D1

Abstract

A refrigerant supercooling circuit comprising a receiver (5) for retention of a liquid-phase refrigerant installed in a refrigerant line (23) connecting a first expansion valve (45) and a plurality of second expansion valves (71), an extraction line (61) for taking out the liquid-phase refrigerant in the receiver (5), a third expansion valve (62) in the extraction line, the portion of the extraction line (61) downstream of the third expansion valve (62) being passed through the receiver (5) or through a supercooling tank (63), the arrangement being such that the degree of opening of the first expansion valve (45) is controlled either according to the refrigerant pressure (P1) on a refrigerant line (20) connecting the delivery side of a compressor (2) and a four-way valve (3), or according to the degree of supercooling (SC) in the outlet of an outdoor heat exchanger (4), or according to the pressure difference across the first expansion valve (45).

Description

Description Refrigerant subcooling circuit, Technical field

The present invention relates to a configuration of a refrigerant subcooling circuit of an air conditioning system, and in particular, relates to indoor heat exchange with one outdoor unit having a compressor driving motor, a compressor, and an outdoor heat exchanger as a unit. TECHNICAL FIELD The present invention relates to a technology aimed at improving the refrigerant cycle efficiency during a cooling operation, for an air conditioning system configured to connect a plurality of indoor units each including a cooling unit. Background art

Conventionally, in a cooling circuit in an air conditioning system during cooling, a high-temperature, high-pressure gas-phase refrigerant is pumped to an outdoor heat exchanger by a compressor and cooled by the outdoor heat exchanger to be converted to a high-pressure liquid-phase refrigerant. After that, it is sent to the indoor unit, expanded inside the indoor unit, absorbs heat of vaporization from the indoor room, recovers it as a low-pressure gas-phase refrigerant, and recovers it to the compressor again.

In addition to the need for more compact outdoor heat exchangers and compressors for air-conditioning systems, and further improvement in operating efficiency, one of the effective means of improving operating efficiency when using air-conditioning systems for cooling operation. There is a supercooling cycle. That is, a cycle for exchanging heat between the high-pressure liquid-phase refrigerant and the low-pressure gas-phase refrigerant is provided in the refrigerant circuit, and the high-pressure liquid-phase refrigerant is brought into a supercooled state.

As a configuration of a conventional supercooling cycle, for example, in U.S. Pat.Nos. 5,228,301 and 5,465,587, refrigerant is extracted from a high-pressure liquid-phase refrigerant pipe downstream of an outdoor heat exchanger. The pipe is branched to expand the high-pressure liquid-phase refrigerant flowing through the extraction pipe into a low-pressure gas-phase refrigerant, and also branch the refrigerant extraction pipe from the low-pressure gas-phase refrigerant pipe downstream of the indoor heat exchanger. The low-pressure gas-phase refrigerant from the extraction pipe is brought into contact with the periphery of the high-pressure liquid-phase refrigerant pipe on the downstream side of the outdoor heat exchanger so as to give a supercooling effect to the high-pressure liquid-phase refrigerant flowing in the refrigerant pipe. . However, in this configuration, the amount of the refrigerant flowing through the refrigerant extraction pipe is used for supercooling without any particular stocking, so that a plurality of refrigerants are required for one outdoor heat exchanger. In an air conditioning system configured to connect an indoor heat exchanger, the amount of refrigerant flowing through the refrigerant circuit changes due to a change in the number of operating indoor heat exchangers, and the amount of refrigerant extracted for supercooling is not stable. The supercooling effect is not stable.

In addition, the low-pressure gas-phase refrigerant flowing through the refrigerant extraction pipe from the downstream side of the indoor heat exchanger absorbs heat in the indoor unit and becomes hot, which is extracted from the high-pressure liquid-phase refrigerant pipe and expanded at low-temperature low-pressure gas. There is also a problem that the temperature difference from the high-pressure liquid-phase refrigerant in the high-pressure liquid-phase refrigerant pipe is reduced by mixing with the high-pressure liquid-phase refrigerant, and a sufficient supercooling effect cannot be obtained.

Also, for example, in US Pat. No. 5,174,123, a refrigerant pipe through which an upstream high-pressure liquid-phase refrigerant flows via an expansion valve and a refrigerant pipe through which a downstream low-pressure gas-liquid refrigerant flows are placed in close proximity. There is disclosed a structure in which the high-pressure liquid-phase refrigerant is supercooled. However, in this structure, the low-pressure gas-liquid refrigerant eventually removes the heat of the high-pressure liquid-phase refrigerant and becomes high in temperature, and the cooling effect in the indoor unit is reduced.

As a general problem, when the outside air temperature is high, the low-pressure gas-phase refrigerant absorbs heat from the outside air, and the amount of heat absorbed from the high-pressure liquid-phase refrigerant decreases. Supercooling is not promoted.

Therefore, as a method of promoting the supercooling effect without increasing the capacity of the outdoor heat exchanger, it is usually fully opened during cooling to allow the gas-liquid mixed refrigerant from the outdoor heat exchanger to pass through (heating). (It sometimes functions as an expansion valve.) It is conceivable that the opening degree of the expansion valve of the outdoor unit is reduced in order to delay the flow of the gas-liquid mixed refrigerant and promote supercooling. However, providing such a throttle valve may lead to an increase in compressor discharge pressure or a decrease in operating efficiency if the throttle degree is too large (that is, if the opening degree is small). Disclosure of the invention

The present invention relates to a refrigerant supercooling circuit configured in a refrigerant circuit during cooling of an air conditioning system for cooling and heating, comprising: a first expansion valve arranged downstream of an outdoor heat exchanger; and a plurality of upstream expansion valves arranged upstream of a plurality of indoor heat exchangers. Liquid-phase refrigerant is placed on the refrigerant line connecting the plurality of second expansion valves In addition to providing a storage receiver, an extraction line for extracting a part of the liquid-phase refrigerant from one of the refrigerant circuits of the air conditioning system is provided, a third expansion valve is provided on the extraction line, and a third expansion valve is provided. In the refrigerant subcooling circuit configured to supercool the liquid-phase refrigerant that is stored in the receiver or after the storage in the extraction line on the downstream side, the gas-liquid mixed refrigerant from the outdoor heat exchanger By controlling the degree of opening of the first expansion valve through which air passes, a plurality of indoor heat exchangers are connected to each outdoor heat exchanger, and the number of operating indoor heat exchangers varies in various ways. Even with such an air-conditioning system, while attaining an appropriate supercooling effect, the load on the compressor and the prime mover for driving the compressor is suppressed to improve the operating efficiency.

The first expansion valve is controlled in accordance with the pressure of the refrigerant in the refrigerant line connecting the compressor discharge side and the directional control valve, so that the degree of opening of the first expansion valve is reduced to enhance the supercooling effect. The throttle can be controlled while detecting the discharge pressure of the compressor to prevent the load on the compressor and the prime mover for driving the compressor from becoming excessive.

Also, by controlling the first expansion valve according to the degree of supercooling at the outdoor heat exchanger outlet, the throttle of the first expansion valve is stopped when an appropriate supercooling effect is obtained, and the throttling is further advanced. In this way, the load on the compressor and the prime mover for driving the compressor is prevented from becoming excessive, and the operating efficiency is prevented from decreasing.

Alternatively, by controlling the first expansion valve in accordance with the pressure difference between the front and rear of the first expansion valve, the first expansion valve controlled in the throttle direction to obtain a supercooling effect can be controlled before and after a certain first expansion valve. Stopping the throttle at the stage when the differential pressure is detected, and further reducing the pressure can prevent the load on the compressor and the prime mover for driving the compressor from becoming excessive.

In the configuration in which the liquid-phase refrigerant being stored in the receiver or taken out after the storage is supercooled by the extraction line on the downstream side of the third expansion valve, first, the downstream of the third expansion valve By passing the extraction line on the side into the receiver and subcooling the liquid-phase refrigerant stored in the receiver, there is no need for another configuration for taking out the liquid-phase refrigerant for supercooling. It is economical.

In this first configuration, the extraction line is to extract the liquid-phase refrigerant from the receiver or from the outdoor heat exchanger, and to perform high-pressure vaporization by the third expansion valve and use for subcooling. The liquid-phase refrigerant can be stably taken out to the extraction line. Secondly, a supercooling tank for storing a liquid-phase refrigerant is arranged in tandem before or after the receiver, and the extraction line takes out the liquid-phase refrigerant from the receiver or the supercooling tank. The downstream portion of the third expansion valve is configured to pass through the subcooling tank. In this way, by configuring the tank as the subcooler separately from the receiver, the degree of freedom of the capacity can be secured without being restricted by the capacity of the receiver. The liquid-phase refrigerant can be taken out from the receiver or the subcooling tank when the liquid-phase refrigerant is taken out to the extraction line, so that the liquid-phase refrigerant can be taken out stably. As in the first and second configurations, in a structure in which the extraction line passes through the receiver or the subcooling tank, the receiver or the extraction line in the subcooling tank is configured by a coiled refrigerant pipe. By installing a plurality of rods along the inner wall of the receiver or the subcooling tank, and supporting the coiled extraction line with the rods, the rod can be connected to the outer end of the extraction line. There is a gap for the rod between the receiver and the inner wall of the supercooling tank, so that the extraction line does not directly contact the inner wall that comes into contact with the outside air. This makes it difficult for the refrigerant state to change, thereby stabilizing the supercooling effect. Further, the refrigerant pipe is disposed integrally in the receiver or the subcooling tank by the support and fixing by these rod members, and the assembly configuration of the subcooling circuit is simplified.

Further, each adjacent one turn of the extraction line is connected and fixed by the coil-shaped refrigerant pipe in the receiver or the subcooling tank, and the refrigerant pipe becomes more stable and integral, and the strength is increased. .

Third, a refrigerant line connecting the receiver and the plurality of second expansion valves is passed through a subcooling pipe having an expanding space, and the extraction line removes a liquid-phase refrigerant from the receiver, A portion downstream of the third expansion valve passes through the subcooling pipe. In the extraction line, a stable liquid-phase refrigerant can be taken out from the receiver, and the structure of the supercooling pipe can be freely set without being restricted by the storage amount of the receiver, and the refrigerant in the extraction line can be extracted. And the amount of heat exchange with the liquid-phase refrigerant in the refrigerant line sent to the second expansion valve.

In the above-described first to third supercooling circuit configurations, the extraction line downstream of the third expansion valve is configured to supercool the liquid-phase refrigerant to be sent to the indoor unit and then to allow the low-pressure gas-phase refrigerant to flow therethrough. Connected to the refrigerant line between the indoor heat exchanger and the directional control valve. This allows the gaseous refrigerant after being supercooled downstream of the third expansion valve to join the low-pressure gaseous refrigerant in the refrigerant line, and as described above, the third expansion valve of the extraction line. On the upstream side, the high-pressure liquid-phase refrigerant is taken out from the outdoor heat exchanger, the receiver, or the supercooling tank, so the differential pressure across the third expansion valve increases, and the supercooling effect increases. You.

Alternatively, an auxiliary refrigerant evaporator for guiding cooling water for cooling the driving motor for the compressor is provided on the refrigerant line between the directional control valve and the suction side of the compressor, and the liquid-phase refrigerant is supercooled. The extracted extraction line is connected to a refrigerant line connecting the direction switching valve and the auxiliary refrigerant evaporator. In this case, in addition to the effects described above, even if the pressure of the vapor refrigerant introduced into the auxiliary heat absorber is low, it is possible to increase the pressure of the refrigerant sucked into the compressor using the waste heat of the extraction line and the prime mover. The load on the compressor can be reduced. In addition, since the waste heat of the prime mover in the auxiliary heat absorber is used for energy for evaporating the liquid-phase refrigerant, a rise in the temperature of the refrigerant drawn into the compressor can be suppressed.

The refrigerant line between the first expansion valve and the receiver has two systems, one of which has a check valve connected to the upper part of the receiver to shut off the flow of the refrigerant from the receiver. The other has a check valve connected to the lower portion of the receiver to shut off the flow of the refrigerant from the first expansion valve, thereby switching the refrigerant line in cooling and heating by two check valves. The operation can be easily performed by the above operation.

The above and other objects, features and advantages of the present invention will become more apparent in the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an overall view of an air conditioning system at the time of cooling including a refrigerant subcooling circuit according to the present invention, and FIG. 2 is similarly equipped with a pressure sensor for controlling a first expansion valve, a temperature sensor, and the like. FIG. 3 is a diagram showing the relationship between the opening degree of the third expansion valve and the cooling effect, and FIG. 4 is a diagram showing the relationship between the third expansion valve and the compressor discharge pressure. FIG. 5 is a diagram showing the relationship between the opening degree of the first expansion valve and the cooling effect, and FIG. FIG. 7 is a diagram showing a relationship between discharge pressure and performance, FIG. 7 is a diagram showing a relationship between a first expansion valve differential pressure and a supercooling effect, and FIG. 8 is a diagram showing a first expansion valve according to the present invention. FIG. 9 is a flowchart showing a second control method of the first expansion valve according to the present invention. FIG. 9 is a flowchart showing the second control method of the first expansion valve according to the present invention. Fig. 11 is a flowchart showing a third control method of the first expansion valve according to the present invention. Fig. 11 is a refrigerant circuit diagram of a configuration in which an extraction line is extended from an outdoor heat exchanger. Fig. 2 shows an embodiment in which the receiver and the subcooling tank are separated, and Fig. 13 shows an embodiment in which the receiver and the subcooling tank are separated and the extraction line for subcooling is taken out from the lower part of the receiver. FIG. 14 is an example of another embodiment in which a receiver and a subcooling tank are separated, and FIG. 15 is a receiver. Fig. 16 shows another embodiment in which the subcooling tank is separated and the extraction line for supercooling is taken out from the lower part of the receiver.Fig. 16 shows an embodiment in which the subcooler is constituted by a double tube heat exchanger. Fig. 17 is a partial cross-sectional side view of the subcooler, Fig. 18 is a plan view of the subcooler, and Fig. 19 is the refrigerant pressure and the specific FIG. 4 is a Mollier diagram showing the relationship. BEST MODE FOR CARRYING OUT THE INVENTION

The refrigerant circuit of the air conditioning (cooling / heating) system shown in FIGS. 1 and 2 according to the present invention will be described. The refrigerant circuit includes a compressor (a multi-compressor in this embodiment) 2, a four-way valve 3 as a directional switching valve, an outdoor heat exchanger 4 (two in this embodiment), a first expansion valve 45, a plurality of second A plurality of indoor heat exchangers 70 etc. corresponding to the expansion valve 71 and the second expansion valve 71 are provided, and a refrigerant line 20 connecting the compressor 2 discharge side and the four-way valve 3 as a refrigerant line. A refrigerant line 26 that connects the four-way valve 3 to the compressor 2 suction side, a refrigerant line 21 that connects the four-way valve 3 to the outdoor heat exchanger 4, and a refrigerant line 26 that is arranged on each outdoor heat exchanger 4 and downstream thereof. Refrigerant line 22 that connects to one expansion valve 45, Refrigerant line 23 that joins from all first expansion valves 45 and branches to all second expansion valves 71, and each second expansion valve 7 1 And a refrigerant line 24 connecting the corresponding indoor heat exchanger 70, and an all indoor heat exchanger 70 and the four-way valve 3. Department is obtained by constituting the refrigerant line 2 5.

In the merging line of the refrigerant lines 23, there is a receiver, which is an evening tank for retaining the liquid-phase refrigerant. An extraction line 61 for extracting the liquid-phase refrigerant in the receiver 5 is provided, and a third expansion valve 62 is interposed in the extraction line 6 1. The line downstream of the tri-expansion valve 62 is passed through the receiver 5 again, and then the extraction line 61 is connected to the refrigerant line 26 as shown in FIG. 1, or as shown in FIG. Connected to the refrigerant line 25. The extraction line 61 constitutes a subcooler 6 by forming, for example, a heat transfer tube 60 which is a coiled refrigerant tube in the receiver 5. In FIGS. 1 and 2, the supercooler 6 is arranged inside the receiver 5, but as will be described later, the subcooler 6 is configured as a unit separate from the receiver 5. It is also possible.

In the refrigerant line 23, the lines from the first expansion valves 45 are merged and then connected to the receiver inflow pipe 51 connected to the upper part of the receiver 5 and to the lower part of the receiver 5 It branches into a heating return pipe 55, and a check valve 4 is interposed in the receiver inflow pipe 51, and a check valve 4 is interposed in the heating return pipe 55, respectively. The check valve 46 blocks the flow of the refrigerant from the receiver 5 to the first expansion valve 45, and the check valve 47 blocks the flow of the refrigerant from the first expansion valve 45 to the receiver 5. It is. Thus, in the cooling cycle, the refrigerant passing through the first expansion valve 45 passes through the check valve 46 and flows in from the upper part of the tank of the receiver 5, and in the heating cycle, the refrigerant flows from the lower part of the tank of the receiver 5. The configuration is such that the refrigerant flowing out flows through the check valve 47 to the first expansion valve 45. This makes it possible to control the flow of the refrigerant in the cooling and heating cycle with a simple configuration using two check valves 46 and 47, thereby reducing costs.

The indoor heat exchanger 70, clean fan 72, etc. are installed in each indoor unit 7, and the other compressor 2, four-way valve 3, auxiliary heat absorber 8, accumulator 9, outdoor heat exchanger 4, receiver All 5 mag are united as outdoor units.

During heating, the refrigerant line 20 from the discharge side of the compressor 2 is connected to the refrigerant line 25 to the indoor unit 7 via the four-way valve 3, and the refrigerant line 26 on the suction side is connected to the outdoor heat exchanger 4 from the outdoor heat exchanger 4. The refrigerant pumped from the compressor 2 flows from the indoor unit 7 to the outdoor unit. At the time of cooling, as shown in FIGS. 1 and 2, the refrigerant line from the discharge side of the compressor 2 is passed through the four-way valve 3. 20 is connected to the refrigerant line 21 to the outdoor heat exchanger 4, and the refrigerant line 26 on the suction side is connected to the refrigerant line 25 from the indoor unit 7. The refrigerant thus cooled flows from the outdoor unit to the indoor unit 7.

The first expansion valve 45 expands the refrigerant from the indoor unit 7 during heating and sends the refrigerant to the outdoor heat exchanger 4 serving as an evaporator, and the second expansion valve 71 operates during cooling. Then, the low-temperature and high-pressure liquid-phase refrigerant from the outdoor heat exchanger 4 and the receiver 5 is expanded, reduced in pressure, and sent to the indoor heat exchanger 70.

An engine 1 is provided as a prime mover for driving the compressor 2.The cooling water, which has absorbed the heat of the engine 1 and has risen in temperature, is guided to the Lage 1 and the heat is released at the Lage 1 11. A cooling water circuit 10 for returning to the engine 1 is formed again to cool the engine 1. Further, an auxiliary circuit 12 leading to an auxiliary heat absorber 8 described later is connected in parallel to the cooling water circuit 10.

A description will be given of a refrigerant circulation cycle during cooling in such an air conditioning system.

The refrigerant is compressed by a compressor (a multi-compressor in this embodiment) 2 to become high-temperature, high-pressure supersaturated steam, which passes through a refrigerant line 20, a four-way valve 3, a refrigerant line 21, and an outdoor heat exchanger 4. While passing through the cooling fins in the outdoor heat exchanger 4, is cooled by the cooling air from the cooling fan 41, is converted into a high-pressure gas-liquid phase refrigerant, and passes through the refrigerant line 22. After passing through the expansion valve 45 and passing through the refrigerant line 23, it is stored in the receiver 5 on the way, is supercooled by the supercooler 6 in the process, and is supercooled by the receiver 5. Only the high-pressure liquid-phase refrigerant is taken out, expanded by the second expansion valve 71, and sent to the indoor heat exchanger 70.

The refrigerant passes through the indoor pipe 75 between the refrigerant line 23 and the indoor heat exchanger 70, and passes through the return pipe 76 from the indoor heat exchanger 70, but is supercooled. Therefore, foaming during passage through the indoor pipe 75 is suppressed. Therefore, it is possible to use smaller-diameter pipes for the indoor pipe 75 and the return pipe 76, and the small diameter makes it easy to bend, thus improving the flexibility of piping. Can be done.

The refrigerant that has passed through the refrigerant line 23, the second expansion valve 71, and the refrigerant line 24 In the exchanger 70, the heat is absorbed and evaporated from the room air to cool the room air. Furthermore, the cooling fan 72 provides a cooling effect in the room. Then, the refrigerant vaporized in the indoor heat exchanger 70 passes through the refrigerant line 25 and the four-way valve 3, and then returns to the compressor 2 via the auxiliary heat absorber 8, the accumulator 9, and the like. The details of the supercooler 6 arranged in the receiver 5 as shown in FIGS. 1 and 2 will be described. The supercooling extraction line 61 extending from the bottom of the receiver 5 passes through the third expansion valve 62, and is again introduced into the receiver 5 from the lower portion of the receiver 5 as described above. After extending upward as a coiled heat transfer tube 60 inside the receiver 5 and extending outside the receiver 5 through the upper part of the receiver 5, as shown in FIG. The refrigerant line 26 is connected to a portion between the four-way valve 3 and the auxiliary heat absorber 8 or, as shown in FIG. 2, to a refrigerant line 25 between the four-way valve 3 and the indoor unit 7. . In this way, a part of the liquid-phase refrigerant is taken out of the receiver 5 in the extraction line 61, expanded in the third expansion valve 62, cooled down, and in the process of flowing through the heat transfer tube 60 inside the receiver 5. Sub-cools the liquid-phase refrigerant.

The outlet end of the receiver inlet pipe 51 extending from the first expansion valve 45 is connected to the upper part of the receiver 5, and the receiver outlet pipe 52 having the inlet lower end near the bottom inside the receiver 5 2 Extends upward.

In such a configuration, the high-pressure liquid-phase refrigerant flowing into the receiver 5 from the receiver inflow pipe 51 flows to the inlet end of the receiver outflow pipe 52 arranged near the bottom of the receiver 5, so that it rises. The refrigerant flows in a direction opposite to the flow of the refrigerant in the heat transfer tube 60, and the supercooling effect of the refrigerant flowing in the heat transfer tube 60 increases.

The heat transfer tube 60 may be provided along the inner peripheral surface of the receiver 5, and the outlet end of the receiver 51 and the receiver outlet tube 52 may be provided therein. As a result, the coil radius of the heat transfer tube 60 is set to the full inner radius of the receiver 5, and the heat exchange area with the liquid-phase coolant is increased, thereby also increasing the supercooling effect. .

Here, the support structure of the heat transfer tube 60 of the subcooler 6 will be described with reference to FIGS. 17 and 18. FIG. Here, the housing of the subcooler 6 is the receiver 5 in the embodiment of FIGS. 1 and 2, but the subcooling tank is used in the embodiments of FIGS. 12 to 15 described later. 6 3 Thus, the subcooler 6 may be configured as a separate unit from the receiver 5. Reference numeral 6 in FIGS. 17 and 18 applies to all cases where the subcooler 6 is a separate unit from the receiver 5.

Along the inner wall of the side wall 5a of the receiver 5 (or the side wall 6a of the subcooler 6, the same applies hereinafter), a plurality (three in this embodiment) of fixed pipes 5b (6b), —Installed and fixed parallel to the axis of bar 5 (supercooler 6). And the fixed pipe

A heat transfer tube 60 is provided in a coil shape on the inner side of 5 b (6 b),

Each time 60a comes into contact with the fixed pipe 5b (6b), it is connected and fixed to the fixed pipe 5b (6b) by welding or using another member. As a result, each turn 60a is fixed at a plurality of positions (three positions in this embodiment) on the circumference in plan view. Further, each turn 60a is formed by welding or using another member at a position 6Ob in plan view between the fixed pipe 5b (6b) and the fixed pipe 5b (6b). In this way, one turn 60a and 60a adjacent to each other are connected and fixed.

With such a configuration, the outer peripheral end of the heat transfer tube 60 can be reliably maintained at a distance from the side wall 5 a of the receiver 5, so that a high cooling effect can be maintained, and the assembling strength is improved. As a result, the durability of the heat transfer tube 60 itself is maintained high, and an excellent cooling effect can be maintained without damage even during long-term use. The member supporting the coiled heat transfer tube 60 is not limited to a pipe such as the fixed pipe 5b (6b), but may be a rod.

Next, various embodiments in which the subcooler 6 is a separate unit from the receiver 5 will be described. First, FIGS. 12 to 15 show that two evening tank-shaped tanks are arranged in a merging line in the refrigerant line 23 connecting the first expansion valve 45 and the second expansion valve 71. One is used as a receiver 5 and the other is used as a subcooling tank 63 including a subcooler 6.

In FIG. 12, the side near the first expansion valve 45 of the two-part tank is a receiver 5, and the side near the second expansion valve 71 is a subcooling tank 6 3. .

In this configuration, the high-pressure liquid-phase or gas-liquid mixed refrigerant sent from the outdoor heat exchanger 4 through the first expansion valve 45 first flows into the receiver 5 from the receiver inflow pipe 51, and becomes a liquid-phase refrigerant. Will be stored. And from the receiver outlet pipe 52 to the tank inlet pipe After passing through 6 4, it flows into the subcooling tank 6 3 from the top of the supercooler 6. Then, the liquid-phase refrigerant is sent to the indoor unit 7 via the refrigerant line 13 from the tank outflow pipe 65 extending at the lower end to the lower part of the subcooling tank 63. .

On the other hand, an extraction line 61 for supercooling extends from the lower part of the subcooling tank 63. The extraction line 61 passes through the third cooling valve 63 after passing through the third expansion valve 62, and forms the heat transfer tube 60 as described above in the supercooling tank 63. After that, the extraction line 61 is connected to a refrigerant line 25 connecting the indoor heat exchanger 70 and the four-way valve 3 as shown in FIG. The extraction line 61 may be connected to a refrigerant line 26 as shown in FIG. The same applies to the following embodiments.

In the subcooling tank 63, the refrigerant flowing from the evening ink inlet pipe 64 and flowing to the lower end of the evening ink outlet pipe 65 and the refrigerant flowing in the heat transfer pipe 60 are countercurrent. However, it has achieved an excellent supercooling effect. In the configuration of the present invention, since the extraction line 61 is configured not to branch off from the middle of the circuit but to extend from the lower part of the tank of the supercooling tank 63, the flow rate of the extracted refrigerant is reduced. By stabilizing the heat exchange efficiency between the coolants, the supercooling effect can be enhanced. This is especially true in the refrigerant circuit according to the present invention in which the number of the outdoor heat exchangers 4 and the number of the indoor heat exchangers 70 are in a one-to-many relationship, due to the change in the number of operating indoor heat exchangers 70. Therefore, it is possible to stably maintain a sufficient supercooling effect because the supply of the extracted refrigerant is stable.

In the embodiment of FIG. 13, similarly to FIG. 12, the receiver 5 near the first expansion valve 45 and the receiver 5 near the second expansion valve 71 on the merging line of the refrigerant line 23 A dual tank consisting of a subcooler tank 63 is provided, but the extraction line 61 extends from the lower part of the receiver 5 tank for supercooling. After passing through the third expansion valve 62, the extraction line 61 passes through the subcooling tank 63, and forms a heat transfer tube 60 in the subcooling tank 63. The configuration is such that the extracted refrigerant is connected to a refrigerant line 25 connecting the indoor heat exchanger 70 and the four-way valve 3. Also in this configuration, in the subcooling tank 63, the flow of the refrigerant flowing from the tank inlet pipe 64 to the ink outlet pipe 65 and the flow of the refrigerant flowing through the heat transfer pipe 60 are opposite flows. Also, since the extraction line 61 extends from the bottom of the receiver 5 at the bottom of the receiver, excellent supercooling effect is obtained. Can be obtained.

In FIGS. 14 and 15, the one closer to the first expansion valve 45 is the subcooling sink 63, and the one closer to the second expansion valve 71 is the receiver 5. That is, the liquid-phase refrigerant sent from the indoor heat exchanger 4 via the first expansion valve 45 flows into the supercooling tank 63 from the tank inflow pipe 64. Then, it is guided to the receiver 5 through the tank outlet pipe 65 and the receiver inlet pipe 51. Then, the liquid-phase refrigerant separated and stored in the receiver 5 flows out of the receiver outlet pipe 52 and is sent to the indoor unit 7 side.

In Fig. 14, an extraction line 61 for supercooling is extended from the lower part of the subcooling tank 63, which is the first tank, and in Fig. 15, the lower part of the tank of the receiver 5 is installed. The extraction lines 61 are extended, and after passing through the third expansion valve 62, they are passed through the subcooling tank 63 to form heat transfer tubes 60 in the subcooling tank 63. Thereafter, the extracted refrigerant is connected to a refrigerant line 25 (26) connecting the indoor heat exchanger 70 and the four-way valve 3. In each case, the flow of the liquid-phase refrigerant in the supercooling tank 63 and the flow in the heat transfer tube 60 are countercurrent, and the extraction line 61 is extended from the lower part of the tank to extract the refrigerant. In that it stabilizes the flow rate of the refrigerant and improves the heat exchange efficiency between the refrigerants, and provides an excellent supercooling effect.

Further, in the embodiments of FIGS. 12 to 15 described above, the receiver 5 as the refrigerant retention tank and the subcooling tank 6 3 as the subcooler 6 are separated from each other. The degree of freedom of each volume can be increased.

Next, an embodiment of the supercooler 6 using the double tube heat exchanger will be described with reference to FIG. In the present embodiment, a receiver 5 for retaining the liquid-phase refrigerant is disposed on a side near the first expansion valve 45 on the merging line in the refrigerant line 23, and a side near the second expansion valve 71. Is provided with a supercooling pipe 67 having an extended space. In this configuration, the refrigerant flowing from the indoor heat exchanger 4 into the receiver 5 via the first expansion valve 45 is separated into gas and liquid, and then the liquid-phase refrigerant passes through the receiver outlet pipe 52 and the supercooling pipe 6 7 The refrigerant flows into the main refrigerant pipe 66 passing through the inside and is sent to the indoor unit 7. An extraction line 61 extends from the lower part of the tank of the receiver 5. After passing through the third expansion valve 62, the extraction line 61 passes through the supercooling pipe 67, and the heat transfer pipe 60 passes through the supercooling pipe 67. After that, it is connected to a refrigerant line 25 connecting the indoor heat exchanger 70 and the four-way valve 3. In other words, the supercooling pipe 67, the main refrigerant pipe 6 "6, and the heat transfer pipe 60 constitute a double pipe heat exchanger, and the refrigerant flowing in the main refrigerant pipe 66 and the heat transfer pipe 60 is made to flow in the opposite direction. The supercooler 6 can be a multi-plate heat exchanger.

As described above, in the embodiment of FIGS. 12 to 16 in which the subcooler 6 is provided as a unit separate from the receiver 5, the receiver 5 is provided similarly to FIGS. 1 and 2. A heating return pipe 55 having a check valve 47 is provided between the bottom of the heater and the first expansion valve 45. In the embodiment shown in FIGS. 12 and 13, between the tank outlet pipe 65 and the receiver outlet pipe 52, the tank outlet pipe 65 and the receiver outlet pipe 52 are connected. A heating return pipe 56 having a check valve that allows only the flow is provided. During heating, the refrigerant from the outdoor unit 7 passes through the heating return pipe 56 and the supercooling tank It is introduced into the receiver 5 beyond 63 and further to the first expansion valve 45 via the heating return pipe 55.

The above configuration is such that the supercooling extraction line 61 extends from the receiver 5 on the refrigerant line 23 or the supercooling tank 63, but as shown in FIG. 11, the outdoor heat exchanger 4 It is also conceivable to adopt a configuration in which more liquid phase refrigerant is taken out.

In FIG. 11, a gas-liquid separator 35 is provided in the middle of the outdoor heat exchanger 4, and the gas-liquid separator 35 is an extraction line having an on-off valve 36 and a third expansion valve 62. The extraction line 61 connected to the heat transfer tube 60 via 61 is connected to the refrigerant line 26 leading to the accumulator 9.

In such a configuration, the refrigerant (eg, 10%) liquefied up to that point is extracted from the gas-liquid separator 35 into the extraction line 61, and the separated high-pressure liquid (R134a rich) Force <, expands in the third expansion valve 62 via the on-off valve 36, and super-cools the liquid refrigerant from the receiver inlet pipe 51 to the receiver outlet pipe 52 while passing through the heat transfer pipe 60, thereby reducing the pressure. It enters the extraction line 61 downstream of the heat transfer tube 60 as a gas-phase refrigerant, and merges with the low-pressure gas-phase refrigerant in the refrigerant line 16.

In the embodiment shown in FIG. 11, temperature sensors 13 1 and 32 are provided on the inlet side and the outlet side (during cooling operation) of the indoor heat exchanger 70, respectively. To 1 It is electrically connected.

In this configuration, the fact that the same temperature signal is supplied from the temperature sensor 31.32 means that the liquid refrigerant passes through the outlet of the indoor heat exchanger 70, that is, the indoor heat exchanger 70. This is equivalent to the fact that the refrigerant has not sufficiently absorbed heat from the room and vaporized (cooled the room), and at this time, the second expansion valve 71 is controlled to be further throttled. On the other hand, if the temperature signal from the temperature sensor 132 is higher than the temperature signal from the temperature sensor 131, it means that the refrigerant has sufficiently absorbed heat from the room and vaporized in the indoor heat exchanger 70. If the difference is too large than a predetermined value, the opening degree of the second expansion valve 71 is increased to increase the amount of refrigerant passing therethrough, and to control the cooling effect. This control has been conventionally employed as a heating degree control method, and controls so that a low-pressure gas always passes through the refrigerant line 25. The second expansion valve 71 acts as a throttle only during the cooling operation shown in the figure, and is a conventional type that is fully opened during heating (during backflow).

Further, the third expansion valve 62 is electrically connected to a temperature sensor 133, 34 arranged to measure a temperature difference between before and after the third expansion valve 62. The same opening degree control is performed so that the gas-phase coolant always passes through the extraction line 61 downstream of the third expansion valve 62.

The above are various embodiments related to the configuration of the subcooler 6 and the subcooling circuit. In the present invention, the opening degree control of the first expansion valve 45 as described later is applied to each of the above embodiments. It is made.

Here, the purpose of the supercooling during the cooling operation and the problems caused by the supercooling will be described with reference to FIG. 19 and the like. In the Mollier diagram showing the relationship between the refrigerant pressure and the specific enthalpy shown in FIG. 19, the pressure increase due to the work of the compressor 2 is shown between Q 1 and Q 2. The high-pressure gas-phase refrigerant Q2 pumped by the compressor 2 is cooled in the outdoor heat exchanger 4, which is a condenser, and enters a gas-liquid mixed state. (The relative enthalpy drops), and the temperature is further reduced by the supercooling degree L 1 minute by the supercooler 6 to become the refrigerant Q3 in a completely liquid state. Then, the high-pressure liquid-phase refrigerant Q 3 is reduced in pressure by the second expansion valve 71 to become a gas-liquid mixed refrigerant Q 4, which removes heat of vaporization in the indoor heat exchanger 70, which is an evaporator, and further superheats Min, the relative pressure rises, and the low-pressure gas-phase It becomes the medium Q 1.

In this, the specific enthalpy rise of the refrigerant in the gas-liquid mixing region between Q4 and Q1, that is, the amount of heat exchange in the evaporator (the indoor heat exchanger 70) is reflected as the cooling capacity. Here, if the subcooler 6 does not have the supercooling effect, in FIG. 19, the position of Q3 moves to the right side of the position shown in FIG. The position of Q4 is also moved to the right, and the amount of movement of the refrigerant in the gas-liquid mixing region is reduced by the amount of movement, and the cooling effect is reduced. Conversely, the degree of supercooling (SC) increases the degree of supercooling L 1 minute and the specific enthalpy of the gas-liquid mixed refrigerant in the indoor exchanger 70 increases, that is, the amount of heat exchange increases, and cooling The effect can be improved.

However, the relative enthalpy rise from Q 4 to Q 1 is constant, and the position of Q 4 moves to the left in the figure by 1 degree of supercooling L compared to the case without supercooling SC. The position of 1 also moves to the left as compared to the case without supercooling (that is, it is closer to the left than Q2), and the compressor 2 has a refrigerant between Q1 and Q2. In addition to increasing the pressure, the work of increasing the specific enthalpy of Q 1 to the set amount of Q 2 is added. That is, the discharge pressure of the compressor 2 must be increased by that much more than the amount corresponding to the original increase in the refrigerant pressure. Thus, while subcooling improves the cooling effect, it has the disadvantage of increasing the workload of the compressor 2 and increasing the load on the compressor and the engine.

In the air conditioning system provided with a large number of indoor units 7 as in the present embodiment, the degree of supercooling also changes according to the number of operating indoor units 7 and the operating state, and the operating state of the compressor 2 must be changed each time. Must. On the other hand, the capacity of the compressor 2 must be set to a very large value, assuming the maximum degree of subcooling L 1 in a state where the indoor unit 7 is operated to the maximum.

Therefore, the problem is how to increase the good supercooling effect (cooling effect) while suppressing the work (ie, discharge pressure) of the compressor 2 and ensuring operating efficiency. In order to reduce the discharge pressure of the compressor 2, in FIG. 19, the pressure difference between Q3 and Q4 should be reduced. To achieve this, it is conceivable to increase the opening of the valve that functions as a throttle valve in the refrigerant circuit to some extent, but this opening does not impair the supercooling effect. It is important to adjust the cooling level, and it is also required that the cooling cycle efficiency COP, that is, the operating efficiency, is not reduced. ―

Here, from FIG. 3, if the opening of the third expansion valve 62 is controlled in the direction of “small” (that is, the direction of throttle), the supercooling degree SC at the inlet of the second expansion valve and the indoor heat exchange The cooling effect (cooling effect) is improved. The greater the differential pressure across the third expansion valve 62, the greater the degree of supercooling SC in the outdoor heat exchanger 4. Accordingly, in order to increase the degree of supercooling SC and enhance the cooling effect, the opening degree of the third expansion valve 62 is reduced, and the start and end of the extraction line 61 are connected to the third expansion valve 6 2 It is desirable to connect to the refrigerant line so that the differential pressure across the valve increases. From this viewpoint, in the above-described subcooling circuit, the starting point of the extraction line 61 is connected to the receiver 5, the subcooling tank 63, or the gas-liquid separator 35 provided in the outdoor heat exchanger 4. Etc. to take out the high-pressure liquid-phase refrigerant, and its end is connected to the refrigerant line 26 as shown in FIG. 1 or FIG. 11, or as shown in FIG. By connecting to a low-pressure gas-phase refrigerant passage line such as connecting to the refrigerant line 25, a large differential pressure across the third expansion valve can be ensured.

However, when the arrangement position of the extraction line 61 and the opening degree of the third expansion valve 62 are set so that the supercooling effect can be sufficiently secured in this way, as shown in FIG. If the differential pressure across the expansion valve 62 is large, the compressor discharge pressure will increase, and the engine load will also increase.

Therefore, in the present invention, the promotion of supercooling and the reduction of the compressor load are obtained by utilizing the first expansion valve 45 which is originally a heating expansion valve. That is, in the cooling cycle described above, since the first expansion valve 45 is disposed between the outdoor heat exchanger 4 and the receiver 5, the refrigerant flows from the outdoor heat exchanger 4 to the receiver 5 without any restriction. The high-pressure liquid-phase refrigerant can be appropriately retained inside the outdoor heat exchanger 4, and the effect of sufficiently cooling the outdoor heat exchanger 4 over the entire surface can be obtained. Therefore, the cooling effect by heat exchange between the refrigerants in the subcooler 6 can be improved as compared with the case where the first expansion valve 45 is not provided. In other words, by operating the first expansion valve 45 as a throttle valve, the refrigerant line 22 is throttled during cooling operation, and the refrigerant is completely liquefied at the outlet of the outdoor heat exchanger 4. It further has a function of promoting cooling of the liquid-phase refrigerant in the receiver 5, that is, the supercooling action. Of course, the first expansion valve 45 is a two-way type having a function as an expansion valve during the heating operation.

However, by making the first expansion valve 45 act as a throttle valve, the supercooling effect is improved (this effect is shown in FIG. 5), while the refrigerant passage is throttled. As a result, the load on the compressor 2 increases, and as a result, the operating efficiency decreases. This relationship is shown in FIG. When the first expansion valve 45 is adjusted in a direction to be narrowed from the reference value, the cooling efficiency is increased due to the improvement of the cooling effect described above, so that the operation efficiency is increased. However, when the throttle opening is reduced to a certain value or more, the cooling capacity continues to improve, and the operating efficiency C 0 P decreases.

Therefore, in the present invention, while obtaining the supercooling effect, the operating efficiency COP is ensured, and furthermore, the optimization control is performed, which enables the realization of both conflicting requirements of reducing the compressor load, In order to improve the operation efficiency, the opening degree of the first expansion valve 45 is controlled by the following method.

First, the first control method will be described. This is done by setting the degree of supercooling in accordance with the operating conditions of various indoor units, and then setting the optimum value of the compressor discharge pressure that does not reduce operating efficiency while ensuring the degree of supercooling. The opening pressure of the first expansion valve 45 is controlled while detecting the discharge pressure of the compressor as appropriate and calculating the deviation from the optimum value.

That is, as shown in FIG. 2, a pressure sensor P1 is disposed on a refrigerant line 20 connecting the compressor 2 and the four-way valve 3, and detects a discharge pressure from the compressor 2. This detected pressure value is input to the controller i 6 to control the opening of the first expansion valve 45.

This control method will be described with reference to the flowchart of FIG. First, the controller 16 sets EV 0 to the first expansion valve opening as an initial value, adjusts the opening of the first expansion valve 45, and performs the cooling cycle operation in this initial setting state. (Step S11). Next, the compressor discharge pressure Pd detected by the pressure sensor P1 is input (step S12), and the target value of the discharge pressure is calculated as a deviation ε from Pd '(step S13), and the deviation ε is calculated. The valve opening change amount is calculated using the valve opening change amount calculation function f Δ Μ ν is calculated (step SI 4), and the first expansion valve according to the valve opening change amount Δ ν ν is calculated.

The opening control of 45 is performed (step S15). Then, the continuation of the supercooling cycle is determined (step S16), and this control is repeated until the compressor discharge pressure reaches the target value.

With this control method, the first expansion valve 45 is controlled in the direction in which the first expansion valve 45 is throttled in a range where the operating efficiency is increased as shown in FIG. 6, thereby improving the supercooling effect and increasing the cooling capacity. If the opening degree of the first expansion valve 45 becomes smaller and the compressor discharge pressure increases, the operating efficiency (COP) tends to decrease, so that the controller 16 has a cooling capacity. The first expansion valve 45 is adjusted to an opening that is optimal to achieve both the improvement in the operating efficiency and the operating efficiency, and when the compressor discharge pressure reaches the target value, the operating efficiency is not further reduced. The stop of the opening is stopped.

Next, a second control method will be described. In the first control method, the compressor discharge pressure related to the operating efficiency is used as a control criterion. In the present method, the degree of supercooling related to the cooling effect is used as the control criterion.

That is, as shown in FIG. 2, a pressure sensor P2 and a temperature sensor T1 are provided in the refrigerant line 22 between the outdoor heat exchanger 4 and the first expansion valve 45. The pressure sensor P 2 detects the refrigerant pressure (condensing pressure) flowing out of the outdoor heat exchanger 4, and the temperature sensor T 1 detects the temperature of the refrigerant flowing out of the indoor heat exchanger 4, and each detected value is a controller. Entered in 16.

This control method will be described with reference to the flowchart of FIG. First, the controller 16 sets EV0 to the first expansion valve opening as an initial value (step S21). Next, the condensing pressure P c detected by the pressure sensor P 2 and the outdoor heat exchanger outlet temperature T 0 ut detected by the temperature sensor T 1 are input (step S 22), and the supercooling degree SC is calculated. Yes (step S2 3). The degree of supercooling SC is calculated as a difference between the saturation temperature Tc with respect to the condensing pressure Pc and the outlet temperature T0ut. In this way, the deviation ε from the supercooling degree target value SC ′ is calculated (step S24), and the valve opening change amount Δ Μ ν is calculated by the valve opening change amount calculation function f using the deviation ε as a human power value. (Step

5 2 5). Then, the opening control of the first expansion valve 45 is performed in accordance with the valve opening change amount ΔΜV (step S 26), and the continuation of the subcooling cycle is determined (step S 27 This control is repeated until the supercooling degree SC at the outdoor heat exchanger 4 outlet reaches the target value. ―

The degree of supercooling SC in the outdoor heat exchanger 4 can also be calculated using the temperature difference before and after the outdoor heat exchanger 4. That is, as shown in FIG. 2, a temperature sensor T 2 is provided on the refrigerant line 21 on the inlet side of the outdoor heat exchanger 4, and the temperature difference between the inlet and outlet of the outdoor heat exchanger 4 is detected by the temperature sensors T 1 · T The supercooling degree SC may be calculated according to the formula (2).

By performing such a control, the supercooling effect is improved and the cooling capacity is increased. In particular, as shown in FIG. 6, the first expansion valve 45 controlled in the throttle direction has a certain opening. The degree of opening is adjusted at a position where the optimal degree of supercooling is achieved to improve both cooling capacity and operating efficiency so that the operating efficiency does not decrease when the temperature is lower than the degree.

Next, a third control method will be described. This is done by setting a reference value for the differential pressure across the first expansion valve 45 to prevent the compressor discharge pressure from rising above a certain level while ensuring a supercooling effect. Is to adjust.

Here, FIG. 7 will be described. As the differential pressure across the first expansion valve 45 increases, both the cooling capacity and the operating efficiency C 0 P increase. However, in order to increase the pressure difference before and after the first expansion valve 45, if the outlet pressure of the first expansion valve 45 decreases, the operating efficiency C 0 P decreases. The inlet pressure of the expansion valve 45 must be increased. For that purpose, the discharge pressure of the compressor 2 must be increased, and although FIG. 3 relates to the third expansion valve 61, the same result is obtained. Therefore, the differential pressure across the first expansion valve 45 cannot be increased without limit.

Therefore, as shown in FIG. 2, in addition to the pressure sensor P2, a pressure sensor P3 is disposed in the refrigerant line 23 between the first expansion valve 45 and the receiver 5. . The pressure sensor P 3 detects the pressure of the refrigerant flowing out of the outdoor heat exchanger 4 after passing through the first expansion valve 45, and the detected value is input to the controller 16. . In other words, the controller 16 can calculate the pressure difference between the front and rear of the first expansion valve 45 by the pressure sensors P2 and P3. This control method will be described with reference to the flowchart of FIG. First, the controller 10 sets EVO to the first expansion valve opening as an initial value (step S31). Next, the first expansion valve differential pressure d PEV is detected from the pressures detected by the pressure sensors P 2 and P 3 (step S 32), and a deviation ε of the discharge differential pressure target value from d PEV ′ is calculated. (Step S33) Based on this, the valve opening change amount ΔΜν is calculated (Step S34), and the opening of the first expansion valve 45 according to the valve opening change amount ΔΜν is calculated. The degree control is performed (step S35). Then, the continuation of the supercooling cycle is determined (step S36), and this control is repeated until the differential pressure across the first expansion valve reaches the target value.

With the above control method, based on the differential pressure across the first expansion valve 45, the cooling capacity is ensured, while the opening of the first expansion valve 45 is optimized so that the compressor load does not become higher than a certain level. Adjust.

The method of controlling the first expansion valve 45 according to the present invention can use the first to third methods described above in combination. For example, both the degree of subcooling at the outlet of the outdoor heat exchanger 4 and the differential pressure across the first expansion valve 45 are detected by the controller 16, and the opening of the first expansion valve 45, which is close to the optimum value for both, is detected. By performing the degree control, more precise control becomes possible. Then, as described above, these control methods are applied to the various air conditioning systems including the supercooling circuit in each of the embodiments shown in FIGS. 1, 2, and 11 to 16, or other embodiments. You can.

Finally, in the embodiment of FIG. 1, as described above, the four-way valve 3 of the refrigerant line 26 and the extraction line 6 1 <that is passed through the receiver 5 downstream of the third expansion valve 62 It is connected to the portion between the auxiliary heat absorber 8 and its significance will be described. As described above, the auxiliary circuit 12 is connected in parallel to the cooling water circuit 10 of the engine 1, and the cooling water whose temperature has increased by cooling the engine 1 passes through the motor valve 13 and the auxiliary heat absorber 8. The engine is configured to exchange heat with the waste heat of the engine 1 and then return to the cooling water circuit 10 again.

On the other hand, the refrigerant that has cooled the room and vaporized in the indoor heat exchanger 70 is returned to the accumulator 9 through the refrigerant line 25, the four-way valve 3, and the refrigerant line 26. Highly wet steam may be sent from 70, with auxiliary heat The refrigerant is evaporated by the waste heat of the engine i absorbed by the absorber 8. By the evaporation effect of the auxiliary heat absorber 8, the liquid particles can be reliably removed from the refrigerant sucked into the compressor 2 together with the liquid phase separation operation of the accumulator 9.

However, when the pressure of the vapor refrigerant sent from the indoor heat exchanger 70 to the auxiliary heat absorber 8 is high, the refrigerant is blocked by the auxiliary heat absorber 8, so that the refrigerant from the indoor unit 7 As a result, the amount of circulating refrigerant is insufficient. Therefore, in the embodiment shown in FIG. 1, a bypass circuit 80 is provided to bypass the auxiliary heat absorber 8 and reach the accumulator 9. Further, a pressure sensor 82 is provided on the inlet side of the auxiliary heat absorber 8, and an electromagnetic valve 81 is provided in the bypass circuit 80. Thus, when the pressure of the vapor refrigerant introduced into the auxiliary heat absorber 8 becomes equal to or higher than the set value, the electromagnetic valve 81 is opened to bypass the vapor refrigerant.

Under such circumstances, in the supercooling cycle in the normal cooling operation, the opening degree of the third expansion valve 62 is reduced, and the refrigerant passing through the downstream heat transfer tube 60 is reduced to a low pressure by this pressure control. By supercooling the refrigerant flowing from the receiver inlet pipe 51 to the receiver inlet pipe 52 in the subcooler 6, the refrigerant passing through the heat transfer pipe 60 is The heat is absorbed and vaporized, and introduced into the auxiliary heat absorber 8 as a gas-phase refrigerant.

By opening the degree of opening of the third expansion valve 62 largely, the refrigerant can be returned to the extraction line 61 downstream of the heat transfer tube 60 in a liquid state. This action has two effects in the following.

First, the first effect will be described. As described above, the vapor refrigerant flowing from the indoor heat exchanger 70 to the accumulator 9 evaporates and expands using the waste heat of the engine 1 in the auxiliary heat absorber 8, but the auxiliary heat absorber 8 When the pressure of the vapor refrigerant introduced into the compressor 2 is low, the pressure of the refrigerant sucked into the compressor 2 is reduced even if the auxiliary heat absorber 8 is used, so that the load on the compressor 2 increases. Therefore, when the pressure detected by the pressure sensor 82 becomes lower than the set value, the third expansion valve 62 provided on the extraction line 61 of the subcooler 6 is opened. As a result, the refrigerant in the liquid phase from the receiver 5 flows into the refrigerant line 26 via the extraction line 61 and flows into the auxiliary heat absorber 8 Will be introduced. Then, the refrigerant in the liquid phase evaporates in the auxiliary heat absorber 8, and after being increased in pressure together with the vapor refrigerant sent from the indoor heat exchanger 70, is sucked into the compressor 2.

That is, even if the pressure of the vapor refrigerant introduced into the auxiliary heat absorber 8 is low, the refrigerant pressure sucked into the compressor 2 can be increased by utilizing the waste heat of the extraction line 61 and the engine 1, The load on compressor 2 can be reduced.

Next, the second effect will be described. As described above, the compressor 2 draws the gas-phase refrigerant returned from the indoor heat exchanger 70 and sends the compressed high-temperature and high-pressure refrigerant to the outdoor heat exchanger 4 during cooling. However, if the temperature of the high-temperature and high-pressure refrigerant becomes too high, the load on the outdoor heat exchanger 4 increases, and a sufficient condensation effect may not be obtained. Further, as described above, the vapor refrigerant returning from the indoor heat exchanger 70 evaporates using the waste heat of the engine 1 in the auxiliary heat absorber 8, but when the liquid droplets contained in the vapor refrigerant are small, However, the waste heat of the engine 1 is absorbed by the refrigerant in the gaseous state and the temperature rises. As a result, the temperature of the gas-phase refrigerant sucked into the compressor 2 also increases.

Therefore, the temperature of the refrigerant pumped from the compressor 2 is detected by the temperature sensor T3, and when the temperature becomes higher than the set temperature, the third expansion valve 62 is opened. Thereby, the refrigerant in the receiver 5 is introduced into the auxiliary heat absorber 8 from the refrigerant line 26 through the extraction line 61 in a liquid state. In this way, the waste heat of the engine 1 in the auxiliary heat absorber 8 is used for energy for evaporating the liquid-phase refrigerant, so that a rise in the temperature of the refrigerant sucked into the compressor 2 can be suppressed. It is. Industrial applicability

The refrigerant subcooling circuit of the heat pump of the present invention can be applied to all types of air conditioners, but in particular, it is an air conditioner used in buildings and factories, that is, one outdoor heat exchanger. This is an invention that exerts a great effect in an air conditioner of a type in which a number of indoor heat exchangers are connected to the heat exchanger.

Claims

The scope of the claims

1. Refrigerant subcooling circuit that constitutes the refrigerant circuit for cooling in the air conditioning system for cooling and heating, with the first expansion valve arranged downstream of the outdoor heat exchanger and the upstream expansion valves of multiple indoor heat exchangers. A liquid-phase refrigerant storage receiver is provided on the refrigerant line connecting the plurality of second expansion valves, and an extraction line for extracting a part of the liquid-phase refrigerant from one of the refrigerant circuits of the air conditioning system. A third expansion valve provided on the extraction line, and a liquid-phase refrigerant taken out of the receiver at or after storage in the receiver at the extraction line downstream of the third expansion valve. Wherein the degree of opening of the first expansion valve is controlled according to the refrigerant pressure in a refrigerant line connecting a compressor discharge side and a direction switching valve. Refrigerant supercooling circuit.

2. The refrigerant subcooling circuit according to claim 1, wherein the extraction line downstream of the third expansion valve passes through the receiver.

3. The refrigerant supercooling circuit according to claim 2, wherein the extraction line takes out a liquid-phase refrigerant from the outdoor heat exchanger. .

4. The refrigerant supercooling circuit according to claim 2, wherein the extraction line takes out a liquid-phase refrigerant from the receiver.

5. The claim according to claim 2, wherein the extraction line is formed of a coiled refrigerant pipe in the receiver, and is supported by a plurality of pipes fixed to the tank inner wall. Refrigerant subcooling circuit.

6. The extraction line according to claim 2, wherein the extraction line is configured by a coiled refrigerant pipe in the receiver, and each adjacent one turn of the refrigerant pipe is connected and fixed. Refrigerant supercooling circuit.

7. A tank for supercooling for storing the liquid-phase refrigerant is arranged in tandem in front of or behind the receiver, and the extraction line takes out the liquid-phase refrigerant from the receiver or the tank for supercooling. 2. The refrigerant supercooling circuit according to claim 1, wherein a portion downstream of the third expansion valve passes through the subcooling tank.

8. The extraction line is constituted by a coil-shaped refrigerant pipe in the receiver, and is supported by a plurality of pipes arranged along the inner wall of the tank. 8. The refrigerant subcooling circuit according to claim 7, wherein

9. The extraction line according to claim 7, wherein the extraction line is formed of a coil-shaped refrigerant pipe in the receiver, and each adjacent one turn of the refrigerant pipe is connected and fixed. Refrigerant supercooling circuit.

10. A refrigerant line connecting the receiver and the plurality of second expansion valves is passed through a supercooling pipe having an expanding space, and the extraction line removes a liquid-phase refrigerant from the receiver, and 2. The refrigerant subcooling circuit according to claim 1, wherein a portion downstream of the third expansion valve passes through the subcooling pipe.

11. The refrigerant line between the first expansion valve and the receiver is divided into two systems, one of which is connected to the upper part of the receiver and has a check valve that shuts off the flow of the refrigerant from the receiver. 2. The refrigerant supercooling circuit according to claim 1, wherein the other has a check valve connected to a lower portion of the receiver to shut off a flow of the refrigerant from the first expansion valve.

12. The extraction line downstream of the third expansion valve, after supercooling the liquid-phase refrigerant stored in the receiver or taken out after storage, switches direction with the plurality of indoor heat exchangers. The refrigerant supercooling circuit according to claim 1, wherein the refrigerant subcooling circuit is connected to a refrigerant line connecting the valve and the valve.

13. An auxiliary refrigerant evaporator that guides cooling water for cooling the compressor driving prime mover is provided on the refrigerant line between the direction switching valve and the compressor suction side. The downstream extraction line is connected to a refrigerant line connecting the direction switching valve and the auxiliary refrigerant evaporator after supercooling the liquid-phase refrigerant stored in the receiver or taken out after the storage. 2. The refrigerant supercooling circuit according to claim 1, wherein

14. A refrigerant supercooling circuit that is included in the refrigerant circuit of the air-conditioning system for cooling and cooling, and includes a first expansion valve disposed downstream of the outdoor heat exchanger and a plurality of upstream heat exchangers upstream of the plurality of indoor heat exchangers. A liquid-phase refrigerant storage receiver is provided on the refrigerant line that connects the arranged multiple second expansion valves, and an extraction line is provided to extract a part of the liquid-phase refrigerant from one of the refrigerant circuits of the air conditioning system. A third expansion valve is provided on the extraction line, and in the extraction line downstream of the third expansion valve, the liquid-phase refrigerant being stored in the receiver or taken out after the storage is supercooled. In the refrigerant supercooling circuit configured to perform, the opening degree of the first expansion valve is controlled according to the degree of supercooling at the outlet of the outdoor heat exchanger. Characteristic refrigerant supercooling circuit.

15. The refrigerant subcooling circuit according to claim 14, wherein the extraction line downstream of the third expansion valve passes through the receiver.

16. The refrigerant supercooling circuit according to claim 15, wherein the extraction line takes out a liquid-phase refrigerant from the outdoor heat exchanger.

17. The refrigerant subcooling circuit according to claim 15, wherein the extraction line takes out a liquid-phase refrigerant from the receiver.

18. The extraction line according to claim 15, wherein the extraction line is formed of a coiled refrigerant pipe in the receiver, and is supported by a plurality of pipes arranged along the tank inner wall. Refrigerant supercooling circuit.

19. The extraction line according to claim 15, wherein the extraction line is formed of a coiled refrigerant pipe in the receiver, and adjacent one turns of the refrigerant pipe are connected and fixed. Refrigerant supercooling circuit.

20. A supercooling tank for storing the liquid-phase refrigerant is arranged in the evening before or after the receiver, and the extraction line takes out the liquid-phase refrigerant from the receiver or the supercooling tank. 15. The refrigerant subcooling circuit according to claim 14, wherein a downstream portion of the third expansion valve passes through the subcooling tank.

21. The extraction line according to claim 20, wherein the extraction line is constituted by a coiled refrigerant pipe in the receiver, and is supported by a plurality of pipes fixed to the tank inner wall. Refrigerant subcooling circuit.

22. The method according to claim 20, wherein the extraction line is formed of a coiled refrigerant pipe in the receiver, and adjacent one turns of the refrigerant pipe are connected and fixed. Refrigerant supercooling circuit.

23. A refrigerant line connecting the receiver and the plurality of second expansion valves is passed through a supercooling pipe having an expanded space, and the extraction line takes out a liquid-phase refrigerant from the receiver and 15. The refrigerant supercooling circuit according to claim 14, wherein a portion downstream of the third expansion valve passes through the inside of the supercooling pipe.

24. The refrigerant line between the first expansion valve and the receiver is divided into two lines, one of which is connected to the upper part of the receiver and has a check valve for shutting off the flow of the refrigerant from the receiver. 15. The refrigerant subcooling according to claim 14, wherein the other has a check valve connected to a lower portion of the receiver to shut off a refrigerant flow from the first expansion valve. circuit.

25. The extraction line on the downstream side of the third expansion valve, after supercooling the liquid-phase refrigerant stored in the receiver or taken out after storage, switches direction with the plurality of indoor heat exchangers. The refrigerant supercooling circuit according to claim 14, wherein the refrigerant supercooling circuit is connected to a refrigerant line connecting the valve and the valve.

26. An auxiliary refrigerant evaporator that guides cooling water for cooling the compressor driving prime mover is disposed on the refrigerant line between the direction switching valve and the compressor suction side. The downstream extraction line is connected to a refrigerant line connecting the directional control valve and the refrigerant auxiliary evaporator after supercooling the liquid-phase refrigerant stored in the receiver or taken out after storage. 15. The refrigerant supercooling circuit according to claim 14, wherein:

27. A refrigerant subcooling circuit that is included in the refrigerant circuit during cooling of the air conditioning system for cooling and heating, and includes a first expansion valve disposed downstream of the outdoor heat exchanger and a plurality of upstream valves disposed upstream of the plurality of indoor heat exchangers. A liquid-phase refrigerant storage receiver is provided on the refrigerant line connecting the plurality of arranged second expansion valves, and an extraction line for extracting a part of the liquid-phase refrigerant from one of the refrigerant circuits of the air conditioning system. A third expansion valve is provided on the extraction line, and a liquid-phase refrigerant taken out of the extraction line downstream from the third expansion valve in the receiver or after being stored in the receiver. A refrigerant supercooling circuit configured to supercool refrigerant, wherein an opening degree of the first expansion valve is controlled according to a pressure difference between the front and rear of the first expansion valve.

28. The refrigerant subcooling circuit according to claim 27, wherein the extraction line downstream of the third expansion valve passes through the inside of the receiver.

29. The refrigerant supercooling circuit according to claim 28, wherein the extraction line takes out a liquid-phase refrigerant from the outdoor heat exchanger.

30. The refrigerant subcooling circuit according to claim 28, wherein said extraction line takes out a liquid-phase refrigerant from said receiver.

31. The extraction line is constituted by a coiled refrigerant pipe in the receiver, and is supported by a plurality of pipes arranged along the inner wall of the tank. A refrigerant supercooling circuit according to claim 28.

32. The extraction line according to claim 28, wherein the extraction line is formed of a coil-shaped refrigerant pipe in the receiver, and one adjacent turn of the refrigerant pipe is connected and fixed. Refrigerant supercooling circuit.

33. A supercooling tank for storing a liquid-phase refrigerant is arranged in the evening before or after the receiver, and the extraction line takes out the liquid-phase refrigerant from the receiver or the supercooling tank. 28. The refrigerant subcooling circuit according to claim 27, wherein the downstream portion of the third expansion valve passes through the subcooling tank.

34. The extraction line is constituted by a coiled refrigerant pipe in the receiver, and is supported by a plurality of pipes fixed to the inner wall of the tank.

7

The refrigerant supercooling circuit according to claim 33.

35. The method according to claim 33, wherein the extraction line is formed of a coil-shaped refrigerant pipe in the receiver, and adjacent one turn of the refrigerant pipe is connected and fixed. A refrigerant supercooling circuit as described in the above.

36. A refrigerant line connecting the receiver and the plurality of second expansion valves is passed through a supercooling pipe having an expanding space, and the extraction line takes out a liquid-phase refrigerant from the receiver and 28. The refrigerant subcooling circuit according to claim 27, wherein a portion downstream of the three expansion valve passes through the subcooling pipe.

37. The refrigerant line between the first expansion valve and the receiver is divided into two systems, and one has a check valve connected to the upper part of the receiver to shut off the flow of the refrigerant from the receiver. 28. The refrigerant supercooling circuit according to claim 27, wherein the other has a check valve connected to a lower portion of said receiver to shut off a refrigerant flow from said first expansion valve.

38. The extraction line on the downstream side of the third expansion valve, after supercooling the liquid-phase refrigerant stored in the receiver or taken out after storage, switches the direction with the indoor heat exchangers. 28. The refrigerant supercooling circuit according to claim 27, wherein the refrigerant supercooling circuit is connected to a refrigerant line connecting the valve.

3. 9. A refrigerant trap evaporator for guiding cooling water for cooling the compressor driving motor is disposed on a refrigerant line between the direction switching valve and the compressor suction side, and the third expansion valve is provided. Downstream of The extraction line on the side is connected to a refrigerant line connecting the directional control valve and the refrigerant auxiliary evaporator after supercooling the liquid-phase refrigerant stored in the receiver or taken out after the storage. 28. The refrigerant supercooling circuit according to claim 27, wherein: