JP2006284035A - Air conditioner and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner capable of securing proper refrigerant circulation without impairing efficiency. <P>SOLUTION: This air conditioner comprising a compressor 2 for compressing a refrigerant, an outdoor heat exchanger 3 for condensing the refrigerant compressed by the compressor 2 in a cooling operation, an expansion valve 7 for expanding the refrigerant condensed by the outdoor heat exchanger 3 in the cooling operation, an indoor heat exchanger 9 mounted indoors for evaporating the refrigerant expanded by the expander 7 in the cooling operation, and a liquid receiver 5 mounted between the outdoor heat exchanger 3 and the expansion valve 7, further comprises a bypass pipe 11 for guiding the refrigerant discharged from the compressor 2 to an upper space of the liquid receiver 5 in a state of bypassing the outdoor heat exchanger 3, and a bypass valve for controlling the flow of refrigerant flowing in the bypass pipe 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an air conditioner and a control method thereof.

  If the cooling operation is performed when the outside air temperature is low as in winter, the refrigerant may condense and accumulate in the condenser or receiver of the outdoor unit, and the high pressure may not be kept high. A sufficient amount of circulating refrigerant as a system cannot be secured (see Patent Document 1).

Conventionally, a head master system is known as a method for ensuring the amount of refrigerant circulated during such low outside temperature cooling operation. FIG. 8 schematically shows an air conditioner employing a head master system. In the figure, an air conditioner 100 includes a compressor 102 that compresses a refrigerant, a condenser (outdoor heat exchanger) 103 that condenses the compressed refrigerant, and a receiver 105 that stores the condensed liquid refrigerant. An expansion valve 107 that expands the liquid refrigerant from the liquid receiver 105 and an evaporator (indoor heat exchanger) 109 that evaporates the expanded liquid refrigerant are provided.
Further, the air conditioning apparatus 100 includes a bypass pipe 111 that guides the high-pressure gas refrigerant compressed by the compressor 102 to the liquid receiver 105 by bypassing the condenser 103, and between the condenser 103 and the liquid receiver 105. And a three-way valve 110 connected to the downstream end of the bypass pipe 111.
In addition, the compressor 102, the condenser 103, the liquid receiver 105, the bypass pipe 111, and the three-way valve 110 are provided in the outdoor unit 115 as shown by being surrounded by a dotted line in FIG. On the other hand, the evaporator 109 and the expansion valve 107 are provided on the indoor side where air conditioning is performed.

The air-conditioning apparatus 100 having the above configuration cools indoor air by latent heat of evaporation obtained by evaporating the low-pressure liquid refrigerant in the evaporator 109 during the cooling operation. In this case, when the outside air temperature decreases, the condensing capacity of the condenser 103 increases, the refrigerant condenses excessively and the condensing pressure decreases. When the condensing pressure is lowered, a differential pressure before and after the expansion valve 107 cannot be secured, and even if the opening degree of the expansion valve 107 is maximized, an appropriate amount of circulating refrigerant cannot be secured.
In order to avoid this, the high-pressure gas refrigerant from the bypass valve 111 is caused to flow through the three-way valve 110 to maintain the high-pressure pressure (condensation pressure) at a predetermined value or higher. That is, the high pressure gas refrigerant discharged from the compressor 102 is mixed with the liquid refrigerant flowing out of the condenser 103, and the liquid refrigerant is warmed by sensible heat of the high pressure gas refrigerant, so that the desired pressure is saturated in the liquid receiver 105. Make a liquid.

JP 11-94377 A (paragraph [0004])

The head master type air conditioner 100 having the above-described configuration has the following problems.
Since the liquid refrigerant that has been supercooled in the condenser 103 is warmed to the saturated liquid state by the discharge gas from the compressor 102, the supercooling obtained by the condenser 103 is wasted, and the refrigeration cycle. Has led to a drop in efficiency.
That is, since the saturated liquid generated in the liquid receiver 105 is obtained by using the sensible heat of the gas discharged from the compressor 102, the amount of input heat is wasted by the sensible heat, and the efficiency is improved. It was causing a decline.
In addition, since it is necessary to flow a high-pressure gas refrigerant corresponding to the amount of heat required to raise the liquid refrigerant flowing out of the condenser 103 to the saturation temperature, the diameter of the bypass pipe 111 must be increased. Accordingly, the three-way valve 110 having a large size has to be adopted. As a result, the apparatus cost has been increased.
Further, the three-way valve 110 needs to guide the high-pressure gas refrigerant from the bypass pipe 111 only at a low outside temperature, and to block the high-pressure gas refrigerant from the bypass pipe 111 at other normal outside temperatures. In order to achieve this, generally, a three-way valve 110 that operates in accordance with a preset pressure is employed. When such a three-way valve 110 is employed, it is difficult to employ it in the air conditioner 100 that performs the heating operation. This is because the three-way valve 110 operates even when the high pressure is low, such as at the start-up during heating. Therefore, when the head master method is employed in an air conditioner that also performs heating operation, a bridge circuit is provided so that the three-way valve is always upstream of the liquid receiver, or the operation of the three-way valve 110 is prohibited during heating operation. A configuration and a control circuit are separately required.

  This invention is made in view of such a situation, Comprising: It aims at providing the air conditioning apparatus which can ensure the amount of circulating refrigerant | coolants appropriate, and its control method, without causing the fall of efficiency. To do.

In order to solve the above problems, the air conditioning apparatus of the present invention employs the following means.
That is, an air conditioner according to the present invention includes a compressor that compresses a refrigerant, an outdoor heat exchanger that is disposed outside and cools the refrigerant compressed by the compressor during cooling operation, and An expansion valve that expands the refrigerant condensed by the outdoor heat exchanger, an indoor heat exchanger that is disposed indoors and that evaporates the refrigerant expanded by the expansion valve during cooling operation, the outdoor heat exchanger, and the expansion And a receiver that is provided between the valve and a bypass that guides the refrigerant discharged from the compressor to an upper space of the receiver by bypassing the outdoor heat exchanger It is characterized by comprising a flow path and a bypass refrigerant control means for controlling the flow of refrigerant flowing through the bypass flow path.

The refrigerant discharged from the compressor is guided to the upper space of the receiver by bypassing the outdoor heat exchanger, and the liquid refrigerant in the receiver is pushed out. Thereby, the liquid refrigerant in the liquid receiver can be supplied into the system.
The refrigerant flowing through the bypass channel is controlled by the bypass refrigerant control means. The bypass refrigerant control means stops and circulates the refrigerant flow flowing through the bypass flow path. In the case of an air conditioner that performs heating operation by heat pump operation, during the heat pump operation, the refrigerant flowing through the bypass flow path is stopped by the bypass refrigerant control means, and the refrigerant flowing through the bypass flow path at the time of cooling operation and at low outside temperature Circulate.
Further, the bypass refrigerant control means may be configured to adjust the flow rate of the refrigerant flow.
As the bypass refrigerant control means, typically, an electronic expansion valve (EEV), an on-off valve, or an on-off valve provided with a fixed throttle is used.
The air conditioner includes a cooling only machine that performs only a cooling operation, a cooling / heating machine that performs a heating operation by a heat pump operation in addition to the cooling operation, and a multi-room heat exchanger that includes a plurality of indoor heat exchangers for one outdoor heat exchanger. Heating / cooling-free multi air conditioner with independent heating / cooling operation in each indoor heat exchanger, including a combination multi-cooling / heating machine having a plurality of outdoor heat exchangers and a plurality of indoor heat exchangers, and a plurality of indoor heat exchangers Etc.

  Furthermore, in the air conditioning apparatus of the present invention, the bypass refrigerant control means is configured to remove the compressor from the compressor via the bypass pipe when the amount of refrigerant flowing through the one or more indoor heat exchangers is equal to or less than a predetermined value. The discharged refrigerant is flowed to the liquid receiver.

For example, at the time of cooling operation at a low outside air temperature (for example, 5 ° C. or lower) such as in winter, the condensation capacity of the condenser, which is an outdoor heat exchanger, increases, and the condensation pressure, that is, the high pressure of the system decreases. When the high pressure of the system is reduced, a sufficient differential pressure before and after the expansion valve cannot be secured, and it becomes difficult to flow a refrigerant flow rate necessary for the system even if the opening degree of the expansion valve is maximized. With this, sufficient refrigerant cannot be circulated through the indoor heat exchanger, and the performance as an air conditioner cannot be ensured.
In the present invention, the bypass refrigerant control means introduces the high-pressure refrigerant discharged from the compressor through the bypass channel into the upper space of the liquid receiver by bypassing the outdoor heat exchanger. When high-pressure refrigerant is introduced into the upper space of the liquid receiver, the liquid refrigerant stored in the liquid receiver is pushed downward due to the pressure difference, and surplus refrigerant is retained in the condenser instead. Thus, the liquid refrigerant retained in the condenser fills the downstream side of the condenser with the liquid refrigerant, and only the portion not filled with the liquid refrigerant functions as a condenser. By reducing the capacity of the outdoor heat exchanger as a condenser in this way, the condensation pressure, that is, the high pressure of the system is increased, and a high pressure capable of giving an appropriate opening degree to the expansion valve is obtained. .
Since the refrigerant flowing through the bypass channel is used only to press the refrigerant liquid level in the liquid receiver, the flow rate flowing through the bypass channel can be remarkably reduced as compared with the conventional head master system. Therefore, the diameter of the refrigerant pipe that realizes the bypass flow path can be reduced, and the valve that can be used as the bypass refrigerant control means can be reduced accordingly, and the cost can be reduced.
Further, since the refrigerant flowing through the bypass channel only presses the refrigerant liquid level in the liquid receiver, the area involved in the heat transfer is limited only to the area of the liquid level. Therefore, the amount of heat transfer can be remarkably reduced as compared with the conventional head master system in which liquid refrigerant and high-pressure gas refrigerant are mixed, and the efficiency of the air conditioner can be improved.

  Furthermore, the air conditioner of the present invention is provided with a plurality of the indoor heat exchangers, and these indoor heat exchangers are connected to the outdoor heat exchanger by a low pressure gas pipe, a high pressure gas pipe and a liquid pipe, respectively. The refrigerant is supplied from the liquid pipe during the cooling operation and from the high-pressure gas pipe during the heating operation to exchange heat with room air, and the bypass refrigerant control means removes the liquid refrigerant stored in the receiver by the bypass refrigerant control means. It can be supplied to the heat exchanger side.

The so-called air conditioning free multi air conditioner, which has multiple indoor heat exchangers and performs heating and cooling operations independently in each indoor heat exchanger, has a high pressure value (condensation pressure) and a low pressure value (evaporation pressure) of the refrigerant pressure circulating in the system. ) Is maintained (that is, by pressure control), the operating state and the number of operating outdoor heat exchangers are changed.
When the evaporation capacity of the indoor heat exchanger operated as an evaporator is balanced with the condensation capacity of the indoor heat exchanger operated as a condenser (cooling / heating balance operation), the outdoor heat exchanger is condensed. The operation is stopped without being operated as an evaporator or an evaporator. The outdoor heat exchanger that has been shut down in this way is, for example, in a so-called evaporator standby state that is connected to the suction side of the compressor and in which no refrigerant flows. However, for example, in the case of a low outdoor temperature such as in winter, the outdoor heat exchanger that is set in the evaporator standby mode has a saturation temperature at the suction pressure (evaporation pressure) of the system lower than the outdoor temperature. Since there is no flow in the refrigerant, the condensed and liquefied refrigerant is retained, and the amount of refrigerant circulating through the indoor heat exchanger is insufficient, which may result in insufficient capacity of the indoor heat exchanger.
In the present invention, in order to avoid such a situation, the liquid refrigerant stored in the liquid receiver is caused to flow to the indoor heat exchanger side by the bypass refrigerant control means, and a necessary refrigerant amount is secured in the indoor heat exchanger. It was decided to.
When flowing the liquid refrigerant stored in the liquid receiver to the indoor heat exchanger, for example, the flow path between the condenser and the liquid receiver is blocked by a valve or the like to positively move toward the indoor heat exchanger side. It is recommended that a liquid refrigerant be allowed to flow through.

  Further, the control method of the air conditioner of the present invention includes a compressor that compresses the refrigerant, an outdoor heat exchanger that is disposed outside and cools the refrigerant compressed by the compressor, and during the cooling operation. An expansion valve that expands the refrigerant condensed by the outdoor heat exchanger; an indoor heat exchanger that is disposed indoors and that evaporates the refrigerant expanded by the expansion valve during cooling operation; and the outdoor heat exchanger; And a liquid receiver provided between the expansion valve and the amount of refrigerant flowing through the indoor heat exchanger, including a case where a high pressure is reduced, including a case where a high pressure is reduced. In this case, the refrigerant discharged from the compressor can be guided to the upper space of the liquid receiver by bypassing the outdoor heat exchanger.

For example, at the time of cooling operation at a low outside air temperature (for example, 5 ° C. or lower) such as in winter, the condensation capacity of the condenser, which is an outdoor heat exchanger, increases, and the condensation pressure, that is, the high pressure of the system decreases. When the high pressure of the system is reduced, a sufficient differential pressure before and after the expansion valve cannot be secured, and it becomes difficult to flow a refrigerant flow rate necessary for the system even if the opening degree of the expansion valve is maximized. With this, sufficient refrigerant cannot be circulated through the indoor heat exchanger, and the performance as an air conditioner cannot be ensured.
In the present invention, the high-pressure refrigerant discharged from the compressor is introduced into the upper space of the liquid receiver by bypassing the outdoor heat exchanger. When high-pressure refrigerant is introduced into the upper space of the liquid receiver, the liquid refrigerant stored in the liquid receiver is pushed downward due to the pressure difference, and surplus refrigerant is retained in the condenser instead. Thus, the liquid refrigerant retained in the condenser fills the downstream side of the condenser with the liquid refrigerant, and only the portion not filled with the liquid refrigerant functions as a condenser. By reducing the capacity of the outdoor heat exchanger as a condenser in this way, the condensation pressure, that is, the high pressure of the system is increased, and a high pressure capable of giving an appropriate opening degree to the expansion valve is obtained. .
Since the bypassed refrigerant is used only to press the refrigerant liquid level in the liquid receiver, the flow rate can be remarkably reduced as compared with the conventional head master system.
Further, since the bypassed refrigerant only presses the refrigerant liquid level in the liquid receiver, the area involved in heat transfer is limited only to the area of the liquid level. Therefore, the amount of heat transfer can be remarkably reduced as compared with the conventional head master system in which liquid refrigerant and high-pressure gas refrigerant are mixed, and the efficiency of the air conditioner can be improved.

  Furthermore, in the control method for an air conditioner of the present invention, a plurality of the indoor heat exchangers are provided, and these indoor heat exchangers are connected to the outdoor heat exchanger by a low pressure gas pipe, a high pressure gas pipe, and a liquid pipe, respectively. In addition, refrigerant is supplied from the liquid pipe during cooling operation and from the high-pressure gas pipe during heating operation to exchange heat with indoor air, and the liquid refrigerant stored in the liquid receiver is transferred to the indoor heat exchanger side. It is characterized by supplying to.

The so-called air conditioning free multi air conditioner, which has multiple indoor heat exchangers and performs heating and cooling operations independently in each indoor heat exchanger, has a high pressure value (condensation pressure) and a low pressure value (evaporation pressure) of the refrigerant pressure circulating in the system. ) Is maintained (that is, by pressure control), the operating state and the number of operating outdoor heat exchangers are changed.
When the evaporation capacity of the indoor heat exchanger operated as an evaporator is balanced with the condensation capacity of the indoor heat exchanger operated as a condenser (cooling / heating balance operation), the outdoor heat exchanger is condensed. The operation is stopped without being operated as an evaporator or an evaporator. The outdoor heat exchanger that has been shut down in this way is, for example, in a so-called evaporator standby state that is connected to the suction side of the compressor and in which no refrigerant flows. However, for example, in the case of a low outdoor temperature such as in winter, the outdoor heat exchanger that is set in the evaporator standby mode has a saturation temperature at the suction pressure (evaporation pressure) of the system lower than the outdoor temperature. Since there is no flow in the refrigerant, the condensed and liquefied refrigerant accumulates in the receiver, so that the amount of refrigerant circulating through the indoor heat exchanger is insufficient and the capacity of the indoor heat exchanger is insufficient.
In the present invention, in order to avoid such a situation, the liquid refrigerant stored in the liquid receiver bypasses the indoor heat exchanger acting as a condenser, and the high-temperature and high-pressure gas is placed in the upper space of the liquid receiver. By introducing the refrigerant, it was pushed down and allowed to flow to the indoor heat exchanger side to secure the necessary amount of refrigerant in the indoor heat exchanger.

  The air conditioner of the present invention is provided with a plurality of the indoor heat exchangers, and these indoor heat exchangers are connected to the outdoor heat exchanger by a low pressure gas pipe, a high pressure gas pipe and a liquid pipe, respectively, The low-pressure gas pipe is provided with an inlet-side pressure regulating valve that performs pressure adjustment based on the inlet-side pressure upstream from the indoor heat exchanger side, and from the liquid pipe during the cooling operation, and from the liquid pipe during the heating operation The refrigerant is supplied from the inside to exchange heat with room air.

  Pressure control is performed by the inlet side pressure regulating valve so that the evaporation pressure on the indoor heat exchanger side, which is the upstream side of this valve, is not more than a predetermined value and the indoor heat exchanger does not freeze.

According to the present invention, the refrigerant discharged from the compressor is guided to the upper space of the liquid receiver by bypassing the heat exchanger for condensation, and the liquid refrigerant in the liquid receiver is simply extruded to serve as a condenser. The ability of the heat exchanger to operate can be reduced to maintain the high pressure of the system. Thus, since it is not necessary to maintain a high pressure using the sensible heat of the refrigerant discharged from the compressor, the efficiency is not reduced.
In addition, even if it has a complex refrigerant circuit that has multiple heat exchangers, the surplus refrigerant retained in the liquid receiver is supplied into the system with a simple circuit configuration, and the system operates stably. You can continue.

Embodiments according to the present invention will be described below with reference to the drawings.
[Cooling machine]
FIG. 1 shows a schematic configuration of a cooling only machine (air conditioner) 1 that performs only a cooling operation.
The cooling only machine 1 includes a compressor 2 that compresses the refrigerant, a condenser (outdoor heat exchanger) 3 that condenses the compressed refrigerant, a receiver 5 that stores the condensed liquid refrigerant, and a receiver. 5 is provided with an expansion valve 7 for expanding the liquid refrigerant from 5 and an evaporator (indoor heat exchanger) 9 for evaporating the liquid refrigerant expanded by the expansion valve 7.
Between the discharge side of the compressor 2 and the liquid receiver 5, a bypass pipe (bypass flow path) 11 that bypasses the condenser 3 and flows a part of the high-temperature and high-pressure discharge gas refrigerant is provided. The bypass pipe 11 is provided with a bypass valve (bypass refrigerant control means) 10.
Among the above configurations, the compressor 2, the condenser 3, the liquid receiver 5, the bypass pipe 11, and the bypass valve 10 are provided in the outdoor unit 15. On the other hand, the evaporator 9 and the expansion valve 7 are provided in the indoor unit 17.
In the present embodiment, the compressor 2, the liquid receiver 5, the bypass pipe 11, and the bypass valve 10 are provided in the outdoor unit 15, but these are not necessarily provided in the outdoor unit 15.

  The compressor 2 compresses the low-temperature and low-pressure gas refrigerant from the evaporator 9 to produce a high-temperature and high-pressure gas refrigerant, and a scroll compressor is preferably used. The refrigerant pipe on the suction side of the compressor 2 is provided with a low pressure sensor P1, and the refrigerant pipe on the discharge side is provided with a high pressure sensor P2. These pressure sensors P1. The output of P2 is output to the input unit 16b of the outdoor control device 16 provided in the outdoor unit 15. Further, the refrigerant pipe on the discharge side of the compressor 2 is provided with a temperature sensor T7, and this output is sent to the input unit 16b.

The condenser 3 is a heat exchanger that exchanges heat by condensing the high-temperature and high-pressure gas refrigerant from the compressor 2 with air that is outside air. An outdoor fan 3a is disposed opposite to the condenser 3, and heat exchange is promoted by forced convection by air sent by the outdoor fan 3a. The outdoor fan 3a is started and stopped by the control unit 16a of the outdoor control device 16, or the rotational speed is controlled.
A temperature sensor T3 is provided in the refrigerant pipe on the upstream side of the condenser 3, and a temperature sensor T4 is provided on the downstream side. Outputs of these temperature sensors T3 and T4 are sent to the input unit 16b of the outdoor control device 16.
The outdoor unit 15 is provided with an outdoor temperature sensor T6, and this output is sent to the input unit 16b. As will be described later, whether or not the outdoor temperature is low is determined based on the outdoor temperature sensor T6.

The liquid receiver 5 is a container in which the liquid refrigerant condensed in the condenser 3 is stored. At a normal outside air temperature that is not a low outside air temperature, surplus refrigerant that has been surplus in the system is stored.
A pressure sensor P <b> 3 is provided in the refrigerant pipe on the downstream side of the liquid receiver 5. The output of the pressure sensor P3 is sent to the input unit 16b of the outdoor control device 16. The pressure sensor P3 detects the pressure of the high-pressure liquid refrigerant, that is, the high-pressure of the system.
A liquid receiver temperature sensor T8 is provided on the side wall of the liquid receiver 5. The output of the receiver temperature sensor T8 is sent to the input unit 16b of the outdoor control device 16, and the liquid level position in the receiver 5 is estimated based on this output value.

  The expansion valve 7 expands the liquid refrigerant supplied from the outdoor unit 15 side substantially in enthalpy. As the expansion valve 7, an electronic expansion valve (EEV) is preferably used, and the opening degree is controlled by the control unit 18 a of the indoor control device 18. The amount of circulating refrigerant circulating in the system is determined by the opening of the expansion valve 7. Moreover, it is controlled by the control unit 18a so that a predetermined degree of superheat (for example, 3 deg) is maintained.

The evaporator 9 is a heat exchanger that evaporates the low-pressure liquid refrigerant from the expansion valve 7 by exchanging heat with room air. A temperature sensor T1 is provided in the refrigerant pipe on the upstream side of the evaporator 9, and a temperature sensor T2 is provided in the refrigerant pipe on the downstream side. The outputs of these temperature sensors T1, T2 are sent to the input unit 18b of the indoor control device 18. The degree of superheat is determined by the temperature obtained by subtracting the temperature sensor T1 from the temperature sensor T2.
An indoor fan 9a is disposed opposite to the evaporator 9, and heat exchange is promoted by forced convection by air sent by the indoor fan 9a. The indoor fan 9a is started and stopped by the control unit 18a of the indoor control device 18, or the rotation speed is controlled.
The indoor unit 17 is provided with an indoor temperature sensor T5, and its output is sent to the input unit 18b. Based on the temperature obtained by the indoor temperature sensor T5, a command issued from the control unit 18a is sent to the input unit 16b of the outdoor control device 16. Based on the command, the control unit 16a of the outdoor control device 16 adjusts the refrigerating capacity by controlling the start / stop of the compressor 2 or the rotation speed thereof, and controls the indoor air temperature.

  The bypass pipe 11 is provided between the discharge side of the compressor 2 and the liquid receiver 5. The downstream end of the bypass pipe 11 is connected to the upper part of the liquid receiver 5 so that the bypass gas refrigerant is guided to the upper space filled with the gas refrigerant.

  As the bypass valve 10, an electronic expansion valve (EEV) capable of opening degree control or an electromagnetic valve that performs ON / OFF operation is used. The bypass valve 10 is subjected to opening degree control and ON / OFF control by the control unit 16 a of the outdoor control device 16. In addition, when using an electromagnetic valve as the bypass valve 10, it is good also as a structure further equipped with the capillary tube (pressure reduction pipe | tube) for flow volume adjustment. Further, instead of or in addition to the capillary tube, a pressure regulating valve that is opened at a predetermined pressure or less may be provided.

  The outdoor control device 16 includes a microcomputer, and controls the outdoor unit 15 based on commands from the sensors in the outdoor unit 15 and the indoor control device 18.

  The indoor control device 18 includes a microcomputer, and controls the indoor unit 17 based on data from each sensor in the indoor unit 17 and the outdoor control device 16.

Next, the operation of the cooling only machine 1 having the above configuration will be described. First, an operation at a normal outside temperature such as in summer will be described, and then an operation at a low outside temperature will be described.
1. Normally, at outside temperature, the high-temperature and high-pressure gas refrigerant compressed by the compressor 2 is condensed in the condenser 3 to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is depressurized substantially in enthalpy after being sent to the expansion valve 7 after a part of the excess refrigerant is stored in the liquid receiver 5. The low-pressure liquid refrigerant evaporates in the evaporator 9 and takes heat from the indoor air sent by the indoor fan 9a. The air which has been deprived of heat and sent to the room is sent into the room, and cooling is realized by lowering the room temperature. The low-pressure gas refrigerant evaporated in the evaporator 9 is guided to the suction side of the compressor 2 and compressed again.
At this time, the bypass valve 10 is closed, and the high-pressure gas refrigerant does not pass through the bypass pipe 11 and is supplied to the liquid receiver 5.

2. When the outside temperature is low, the basic refrigerant flow constituting the refrigeration cycle is the same as in the case of the normal outside temperature. Therefore, only different parts will be described.
When the temperature measured by the outdoor temperature sensor T6 becomes a low outside air temperature of, for example, 5 ° C. or less, the high pressure decreases, it becomes difficult to secure the amount of refrigerant circulated by the expansion valve 7, and the desired cooling capacity cannot be obtained. The operation described below (referred to as an operation for introducing a high-pressure gas refrigerant into the receiver 5, hereinafter referred to as “hot gas introduction operation”) is performed. Even when the outside air temperature is low, when the circulating refrigerant amount can be secured by the appropriate opening degree of the expansion valve 7 and a desired cooling capacity can be obtained, the above-described normal outside air temperature is not performed without performing the hot gas introduction operation. Do the operation.

The determination as to whether or not to perform the hot gas introduction operation is performed as follows, for example.
When the degree of superheat (T2-T1) of the evaporator 9 is a predetermined value (for example, 15 deg) or more and the opening degree of the expansion valve 7 exceeds a predetermined value larger than that during normal operation, the hot gas introduction operation is performed. Do. That is, if the degree of superheat of the evaporator 9 is equal to or greater than a predetermined value, it means that the liquid refrigerant has not sufficiently flowed into the evaporator 9, and in this case, the opening degree of the expansion valve 7 is equal to or greater than the predetermined value. This is because it means that the amount of circulating refrigerant is insufficient.
Further, when the high pressure falls below a predetermined value, the hot gas introduction operation may be performed. That is, as in the prior art, when the high pressure falls below a predetermined value, the circulation amount is insufficient, and the amount of hot gas introduced may be adjusted so as to ensure the high pressure even at low outside air temperatures. . This can prevent the circulation amount from being insufficient.

  When the expansion valve 9 has a fixed opening, it is assumed that the low-pressure pressure has become a predetermined value (0.47 MPa) or less, instead of the control determined by the opening of the expansion valve 9. This is because if the low pressure is lower than the predetermined value, it means that sufficient refrigerant is not flowing in the evaporator 9. As the low pressure, the output value of the low pressure sensor P1 provided on the suction side of the compressor 2 is used.

  Furthermore, in addition to these determination criteria, the discharge temperature of the compressor 2 (measured by the temperature sensor T7) may be measured. That is, the hot gas introduction operation is performed when the discharge temperature becomes equal to or higher than a predetermined value (for example, 120 ° C.). This is because the higher the discharge temperature, the greater the degree of superheat. However, the determination based on the discharge temperature is not an unequivocal reason for the lack of cooling capacity, so it must be combined with other criteria.

When it is determined that the hot gas introduction operation is necessary as described above, the operation control is performed as follows.
The fully closed bypass valve 10 is opened, and a part of the high-pressure gas refrigerant from the compressor 2 is guided to the liquid receiver 5. The high-pressure gas refrigerant guided to the upper space of the liquid receiver 5 presses and pushes down the liquid level of the liquid refrigerant stored in the liquid receiver 5. When the liquid level in the liquid receiver 5 is pushed down, the liquid refrigerant in the liquid receiver 5 is pushed out, and surplus refrigerant is retained in the condenser 3 instead. The liquid refrigerant retained in the condenser 3 partially fills the lower part of the refrigerant flow path of the condenser 3. Since the portion filled with the liquid refrigerant does not operate as a condenser, the condensing capacity of the condenser 3 is exhibited only by the portion not filled with the liquid refrigerant. As a result, the size of the condenser 3 is apparently seen. Becomes smaller. Thus, the condensing capacity of the condenser 3 is reduced, so that the condensing pressure in the condenser 3 increases, and the pressure of the high-pressure refrigerant guided to the expansion valve 7 is restored to an appropriate value.

If the bypass valve 10 is suddenly opened, the supply of liquid refrigerant to the system is abruptly performed, the opening degree control of the expansion valve 7 cannot catch up, and excess liquid refrigerant is flowed to the evaporator 9 to evaporate. There is a possibility that the liquid refrigerant that could not be sucked into the compressor 2 (liquid back). In order to avoid this, the opening degree of the bypass valve 10 during the hot gas introduction operation is controlled as follows, for example.
When an electronic expansion valve is used as the bypass valve 10, control is performed to increase the opening of the bypass valve 10 with a time constant that does not exceed the response of the expansion valve 7. And it detects that the opening degree of the expansion valve 7 entered the appropriate range at the time of normal operation, and stops the increase in the opening degree of the bypass valve 10. Thereafter, the opening degree of the bypass valve 10 is adjusted so that the opening degree of the expansion valve 7 is within the appropriate range, or the bypass valve 10 is closed.

  Further, the opening degree of the bypass valve 10 may be controlled based on the measured pressure of the pressure sensor P3 provided in the refrigerant pipe connecting the liquid receiver 5 and the expansion valve 7. Specifically, a pressure value lower than the discharge pressure of the compressor 2 is set as an upper limit pressure value, and control is performed so as not to exceed the upper limit pressure value. Then, the opening degree of the bypass valve 10 is increased so as to maintain a high pressure (for example, about 2.9 MPa) appropriate for the system. At this time, in order to avoid the liquid back, the opening degree of the bypass valve 10 is controlled so that the rate of change of the pressure sensor P3 with respect to time becomes a predetermined value or less. Further, the same operation control can be realized by providing a pressure regulating valve in the bypass circuit.

  When an electromagnetic valve is provided as the bypass valve 10, control is performed as follows. In addition to the solenoid valve, a capillary tube may be provided as a fixed throttle for adjusting the flow rate.

In the case of a solenoid valve, since the opening degree cannot be controlled like an electronic expansion valve, ON / OFF control is performed as follows.
ON / OFF control of the bypass valve 10 is performed by a receiver temperature sensor T8 provided in the receiver 5. That is, the receiver temperature sensor T8 is attached at a predetermined position below the liquid level before opening the bypass valve 10, and the bypass valve 10 is opened until the liquid level is detected by the receiver temperature sensor T8. I will do it. The liquid level is detected by the temperature change of the receiver temperature sensor T8. That is, when the liquid level exists above the position of the receiver temperature sensor T8, the receiver temperature sensor T8 outputs the temperature of the low-temperature liquid refrigerant equivalent to the outside air temperature, and the liquid level is the receiver temperature. This is because the receiver temperature sensor T8 outputs a high discharge gas temperature from the compressor 2 when it is positioned below the position of the sensor T8.
The reason why the sensor T8 is provided below the level before the bypass valve 10 is opened is that the liquid refrigerant in the liquid receiver 5 is pushed out when the liquid level is lowered. The position of the sensor T8 is set to an appropriate position that does not cause a liquid back because excessive liquid refrigerant may flow to the expansion valve 7 and cause a liquid back if it is positioned significantly downward. Further, when determining the position of the sensor T8, it is necessary to set it in consideration of the amount that the high-pressure gas refrigerant condenses and raises the liquid level.
Also, periodic opening / closing control of the bypass valve 10, that is, opening for a predetermined time and closing for a predetermined time are repeated, and when the opening degree of the expansion valve 7 on the indoor unit side falls within an appropriate range, the closing time may be lengthened. You can achieve your purpose.

  In addition, when the liquid refrigerant is not stored in the liquid receiver 5 before the start of the hot gas introduction operation, the temperature change of the liquid receiver temperature sensor T8 cannot be obtained, and thus the above-described control cannot be performed. In this case, considering the degree of supercooling, if the degree of supercooling is less than or equal to a predetermined value or 0, it is determined that no refrigerant is flowing, and control is performed to close the bypass valve 10.

  Further, regardless of whether an electronic expansion valve is used as the bypass valve 10 or a solenoid valve is used, the bypass valve 10 is used after a predetermined time has elapsed (for example, several tens of seconds to several minutes) from the start of the hot gas introduction operation. The control may be closed, and the opening and closing may be repeated as described above. Thereby, simple control is achieved.

As described above, according to the cooling only machine 1 according to the present embodiment, the following operational effects are obtained.
The bypass pipe 11 is provided, and the high-pressure gas refrigerant discharged from the compressor 2 is introduced into the upper space of the liquid receiver 5 by bypassing the condenser 3, and surplus liquid stored in the liquid receiver 5. Since the refrigerant is caused to flow into the system due to a pressure difference from the discharge pressure caused by the pipe pressure loss accompanying the refrigerant flow in the pipe path to the discharge pipe, the condenser and the receiver, the downstream side of the condenser 3 It will be filled with the liquid refrigerant which is an excess refrigerant, and only the part which is not filled with the liquid refrigerant will function as a condenser. By reducing the capacity of the condenser as described above, the condensation pressure, that is, the high pressure of the system is increased, and a high pressure capable of giving an appropriate opening degree to the expansion valve 7 is obtained. Therefore, the amount of refrigerant necessary for the evaporator 9 can be supplied, and the capacity does not become insufficient.
Further, since the refrigerant flowing through the bypass pipe 11 is used only to press the refrigerant liquid level in the liquid receiver 5, the flow rate flowing through the bypass pipe 11 is significantly reduced compared to the conventional head master system. Can do. Therefore, the diameter of the refrigerant pipe that realizes the bypass pipe 11 can be reduced, and accordingly, the bypass valve 10 can also be reduced, thereby reducing the cost.
Further, since the refrigerant flowing through the bypass pipe 11 only presses the liquid level of the liquid receiver 5, the area involved in heat transfer is limited only to the area of the liquid level. Therefore, the amount of heat transfer can be remarkably reduced as compared with the conventional head master method, and the efficiency of the refrigeration cycle can be improved. In order to minimize the heat transfer between the high-pressure gas refrigerant and the liquid refrigerant, it is preferable that the liquid receiver 5 has a vertically elongated shape to reduce the liquid surface area.

[Air conditioning unit]
The present invention can be applied not only to the cooling-only machine 1 but also to a cooling / heating machine that performs a heating operation by a heat pump operation as shown in FIG. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
The air conditioner (air conditioner) 1A is different from the air conditioner 1 of FIG. 1 in that a four-way valve 19 and an outdoor heat exchanger side expansion valve 20 are provided.
The four-way valve 19 is used for switching between cooling operation and heating operation. FIG. 2 shows the cooling operation, in which the discharge side of the compressor 2 and the outdoor heat exchanger 3 are connected, and the suction side of the compressor 2 and the indoor heat exchanger 9 are connected. Thus, during the cooling operation, the outdoor heat exchanger 3 serves as a condenser, and the indoor heat exchanger 9 serves as an evaporator.

  In the heating operation, the four-way valve 19 is switched, the discharge side of the compressor 2 and the indoor heat exchanger 9 are connected, and the suction side of the compressor 2 and the outdoor heat exchanger 3 are connected. Thus, the outdoor heat exchanger 3 becomes an evaporator, and the indoor heat exchanger 9 becomes a condenser. At this time, the outdoor heat exchanger side expansion valve 20 operates as a throttle valve.

  The bypass pipe 11 is connected between the discharge side of the compressor 2 and the liquid receiver 5 and is similar to the cooling-only machine 1 of FIG.

  In FIG. 2, the outdoor control device 16, the indoor control device 18, and the sensors are not shown, but are simply omitted and are provided in the same manner as in FIG. 1. This is the same also about each air conditioning apparatus 1B-1F demonstrated below.

The bypass valve 10 remains closed during the heating operation. Thus, since it is only necessary to close the bypass valve 10 during the heating operation, the circuit configuration and control thereof are extremely simple as compared with the conventional head master system.
Since the other effect by the bypass 11 and the bypass valve 10 is the same as that of the cooling only machine 1 of FIG. 1, the description is abbreviate | omitted.

[Multi air conditioner]
The present invention can be applied not only to the cooling-only machine 1 but also to a multi-cooling / heating machine including a plurality of indoor heat exchangers as well as a heating operation by a heat pump operation as shown in FIG. In the figure, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.
The multi air conditioner (air conditioner) 1B is provided with a plurality of indoor heat exchangers 9 and expansion valves 7 with respect to the air conditioner of FIG. 2, and between the receiver 5 and the expansion valve 7. The difference is that a supercooling heat exchanger 22 is provided. Other configurations are the same.

The supercooling heat exchanger 22 is a double-pipe or plate-type heat exchanger, and provides supercooling to the liquid refrigerant from the liquid receiver 5. That is, a part of the liquid refrigerant flowing out from the liquid receiver 5 is branched and decompressed by the expansion valve 22a to produce a low-temperature refrigerant. By this low-temperature refrigerant, the liquid refrigerant flowing through the supercooling heat exchanger 22 without branching is made. Cool and give supercooling. Thus, even when the refrigerant pipe connecting the outdoor unit 15 and the indoor unit 17 is long and the pressure loss is large, the refrigerant can be transported to the expansion valve 7 as a liquid refrigerant without being in a gas-liquid two-phase state. it can.
The stop of the hot gas introduction operation may be determined by a temperature sensor (not shown) provided at the outlet of the liquid refrigerant pipe of the supercooling heat exchanger 22. That is, when the temperature of the temperature sensor provided at the outlet of the liquid refrigerant pipe of the supercooling heat exchanger 22 rises, it means that the high-pressure gas refrigerant from the bypass pipe 11 has flown. In this case, the bypass valve 10 is closed. Stop hot gas introduction operation. Thereby, even when the liquid refrigerant is exhausted in the liquid receiver 5 and the liquid level cannot be detected by the temperature sensor T8 (see FIG. 1), the hot gas introduction operation can be stopped.
Since the other effect by the bypass pipe 11 and the bypass valve 10 is the same as that of the air conditioning apparatus 1 and 1A of FIG. 1 and FIG. 2, the description is abbreviate | omitted.

[Multi air conditioner]
The present invention can be applied not only to the cooling-only machine 1 but also to a combined multi-cooling / heating machine provided with a plurality of outdoor units 15 in addition to the multi-cooling / heating machine 1B shown in FIG. 3 as shown in FIG. . In the figure, the same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.
The combined multi-type air conditioner (air conditioner) 1C includes a plurality of (two in FIG. 4) outdoor units 15.
The upstream side (the discharge side of the compressor 2) of the bypass valve 10 of each outdoor unit 15 is connected by a connecting pipe 23. Thereby, even when the compressor 2 of one outdoor unit 15 is stopped, the discharge pressure of the compressor 2 of the other outdoor unit 15 can be used, and the hot gas introduction operation can be performed. .
Since the other effect by the bypass pipe 11 and the bypass valve 10 is the same as that of the air conditioning apparatus 1, 1A, 1B of FIG. 1 thru | or FIG. 3, the description is abbreviate | omitted.

[Air conditioning free multi air conditioner]
The present invention is applied not only to the cooling-only machine 1 but also to a cooling / heating free multi-air conditioner including a plurality of indoor heat exchangers and independently performing heating / cooling operation in each indoor heat exchanger as shown in FIG. be able to. In the figure, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals, and the description thereof is omitted.
The cooling / heating free multi-air conditioner (air conditioning apparatus) 1D has a plurality of indoor units 17 for one outdoor unit 15, and each indoor unit 17 can independently perform a cooling operation and a heating operation. It is like that.

  The outdoor unit 15 includes a compressor 2, an outdoor heat exchanger 3, a liquid receiver 5, a four-way valve 19, an outdoor heat exchanger side expansion valve 20, a supercooling heat exchanger 22, and an expansion valve 22a. Since the function is the same as that of the outdoor unit 15 shown in FIG. 3 and FIG. 4, description thereof is omitted.

  The outdoor unit 15 and the indoor unit 17 are connected by a low pressure gas pipe 24, a high pressure gas pipe 26, and a liquid pipe 28.

  Each indoor unit 17 is provided with a diversion controller 30. The shunt controller 30 includes a four-way valve 32 and a capillary tube 33 that is a fixed throttle. By switching the four-way valve 32, the low-pressure gas from the indoor heat exchanger (evaporator) 9 is guided to the low-pressure gas pipe 24 during cooling, and the high-pressure gas from the high-pressure gas pipe 26 is heated to the indoor heat exchanger ( It is supposed to lead to the condenser 9). Each indoor unit 17 shown in FIG. 5 is in a cooling operation.

  The outdoor unit 15 shown in FIG. 5 is set at the time of cooling main operation. In this case, the discharge gas from the compressor 2 is guided to the outdoor heat exchanger 3 through the four-way valve 19, and further, It is guided to the indoor unit 17 through the high pressure gas pipe 26. The high-pressure gas guided by the high-pressure gas pipe 26 is used to heat the indoor unit 17 (in the case of heating operation, the four-way valve 32 of the shunt controller 30 is switched, and the high-pressure gas pipe 26 and the indoor heat exchanger 9 are connected. .). Since all the indoor units 17 shown in FIG. 5 are in a cooling operation, the high-pressure gas supplied by the high-pressure gas pipe 26 passes through the four-way valve 32 of the shunt controller 30 and is depressurized by the capillary tube 33. It is led to the low pressure gas pipe 24. This prevents the refrigerant from staying in the high-pressure gas pipe 26 and holding the liquefied refrigerant.

  The liquid refrigerant condensed in the outdoor heat exchanger 3 passes through the receiver 5 and is supercooled by the supercooling heat exchanger 22 and then sent to the indoor unit 17 through the liquid pipe 28. The liquid refrigerant sent to the indoor unit 17 is expanded by the expansion valve 7 and then evaporated in the indoor heat exchanger 9 to take heat from the indoor air and cool it. The low pressure gas evaporated in the indoor heat exchanger 9 passes through the four-way valve of the branch flow controller 30, is led to the low pressure gas pipe 24, and is returned to the compressor 2 of the outdoor heat exchanger 15.

  The air-conditioning free multi air conditioner 1D having the above-described configuration performs the hot gas introduction operation by opening the bypass valve 10 at a low outside air temperature, similarly to the air conditioners 1, 1A, 1B, and 1C shown in FIGS. Since this effect is the same, the description thereof is omitted.

As one of the operation modes of the air conditioning free multi-air conditioner 1D, when the evaporation capacity of the indoor heat exchanger 9 operated as an evaporator is balanced with the condensation capacity of the indoor heat exchanger 9 operated as a condenser (For example, when the number of indoor heat exchangers 9 operating as evaporators is the same as the number of indoor heat exchangers 9 operating as condensers), the outdoor heat exchanger 3 is also evaporated as a condenser. There is also an operation mode (cooling / heating balance operation) in which the operation is stopped without being operated as a vessel.
The outdoor heat exchanger 3 whose operation has been stopped in this manner is connected to the suction side of the compressor 2 by switching the four-way valve 19 and is in a so-called evaporator standby state in which the refrigerant does not flow. In this state, when the outside air temperature is low, the outdoor heat exchanger 3 placed on the evaporator stand-by causes the saturation temperature at the suction pressure (evaporation pressure) of the system to be lower than the outside air temperature. Since there is no flow at 5, the condensed and liquefied refrigerant accumulates, the system becomes short of refrigerant, and the indoor heat exchanger 9 may become insufficient in capacity.
In order to avoid such a situation, the liquid refrigerant stored in the liquid receiver 5 is pushed out to the indoor heat exchanger 9 side by opening the bypass valve 10. In this case, since the outdoor heat exchanger side expansion valve 20 is closed, the liquid refrigerant is supplied to the indoor heat exchanger 9 side.
Thereby, the refrigerant | coolant amount required in the indoor heat exchanger 9 can be ensured, and the capability shortage in the indoor heat exchanger 9 can be avoided.

[Air conditioning free combination multi air conditioner]
The present invention can be applied not only to the cooling-only machine 1 but also to a cooling / heating-free combined multi-air conditioner having a plurality of outdoor units of the cooling / heating-free multi-air conditioner shown in FIG. 5, as shown in FIG. In the figure, the same components as those in FIGS. 1 to 5 are denoted by the same reference numerals, and the description thereof is omitted.
The air-conditioning / free combination multi-air conditioner (air conditioner) 1E is different from the air-conditioning / free air conditioner 1D shown in FIG.
Therefore, since the effect of the hot gas introduction operation by the operation of the bypass valve 10 is the same, the description thereof is omitted. Further, when the evaporation capacity and the condensation capacity of the indoor heat exchanger 9 are balanced (cooling / heating balance operation) and the amount of refrigerant circulating through the indoor heat exchanger 9 is insufficient, the bypass valve 10 is opened and the liquid refrigerant is heated to the indoor heat. Since the configuration, action, and effect flowing to the exchanger 9 side are the same, the description thereof is omitted.

FIG. 7 shows a configuration in which the air conditioning / free combination multi-air conditioner of FIG. 6 is provided with an evaporation pressure adjusting valve.
7 is provided with an evaporation pressure adjustment valve (EPR, inlet side pressure adjustment valve) 40 in the refrigerant pipe on the outdoor unit 15 side connected to the low pressure gas pipe 24. ing. This pressure regulating valve 40 is for performing pressure control so that the evaporation pressure on the indoor unit side, which is the upstream side of this valve, does not reach a predetermined value and the indoor unit heat exchanger does not freeze. It is. Thereby, even if the suction pressure as the system when the above-described evaporator standby is performed becomes low, the evaporation pressure on the indoor unit side can be kept appropriate, so that the indoor heat exchanger 9 can be cooled without freezing. You can continue driving. This is not only the case where the evaporation capacity of the indoor heat exchanger 9 operated as an evaporator is balanced with the condensation capacity of the indoor heat exchanger 9 operated as a condenser, but also the operation as a condenser. It is also useful when the outdoor heat exchanger 3 is used as an evaporator in heating-dominated operation where the indoor heat exchanger 9 has a large condensing capacity. That is, when the outside air temperature is, for example, 0 ° C. or less, the evaporation temperature of the outdoor heat exchanger naturally falls below the outside air temperature. When the temperature of the indoor heat exchanger 9 becomes 0 ° C. or lower, the condensed water is frozen, but is upstream of the evaporation pressure regulating valve (EPR) 40. Freezing can be avoided by keeping the evaporation temperature in the indoor heat exchanger 9 at or above the set pressure of the valve. By setting the saturation temperature of the set pressure of the valve to about 5 ° C., stable operation can be realized without impairing the cooling capacity.
In addition, the low pressure gas pipes on the outdoor unit 15 side are connected to each outdoor unit 15 as shown in FIG. You may try to go down. Further, in the case of defrost operation in which frost adhering to the outdoor heat exchanger is melted, an evaporating pressure adjusting valve 40 is provided by providing an electromagnetic valve in parallel with the evaporating pressure adjusting valve 40 and opening the electromagnetic valve. It is also important to stop the function.

As described above, the bypass pipe 11 and the bypass valve 10 can be easily attached not only to the cooling-only machine 1 shown in FIG. 1 but also to each of the air conditioners 1A to 1F shown in FIGS. it can. In addition, since the control only needs to close the bypass valve 10 during the heat pump operation, the system can be configured very simply.
In the case where each indoor heat exchanger 9 is configured to perform air conditioning independently as shown in FIGS. 5 to 7, when the operation mode of each indoor heat exchanger 9 changes, the bypass valve 10. It is preferable to control so as to be closed. This is because when the operation mode of the indoor heat exchanger 9 changes, the amount of circulating refrigerant varies, making it difficult to grasp the appropriate amount of refrigerant.

It is the schematic block diagram which showed the cooling only machine provided with the bypass pipe and bypass valve of this invention. It is the schematic block diagram which showed the air conditioning machine provided with the bypass pipe and bypass valve of this invention. It is the schematic block diagram which showed the multi air conditioning machine provided with the bypass pipe and bypass valve of this invention. It is the schematic block diagram which showed the combination multi air conditioning machine provided with the bypass pipe and bypass valve of this invention. It is the schematic block diagram which showed the air conditioning free multi air conditioner provided with the bypass pipe and bypass valve of this invention. It is the schematic block diagram which showed the air-conditioning free combination multi air conditioner provided with the bypass pipe and bypass valve of this invention. It is the schematic block diagram which showed the air conditioning free combination multi air conditioner provided with the bypass pipe and bypass valve of this invention, and also provided with the evaporation pressure regulating valve. It is the schematic block diagram which showed the cooling only machine which employ | adopted the conventional head master system.

Explanation of symbols

1, 1A, 1B, 1C, 1D, 1E, 1F Air conditioner 2 Compressor 3 Outdoor heat exchanger 5 Receiver 7 Expansion valve 9 Indoor heat exchanger 10 Bypass valve (bypass refrigerant control means)
11 Bypass pipe (bypass flow path)

Claims (6)

A compressor for compressing the refrigerant;
An outdoor heat exchanger that is arranged outside and condenses the refrigerant compressed by the compressor during cooling operation;
An expansion valve for expanding the refrigerant condensed by the outdoor heat exchanger during cooling operation;
An indoor heat exchanger that is disposed indoors and that evaporates the refrigerant expanded by the expansion valve during cooling operation;
In an air conditioner comprising: a liquid receiver provided between the outdoor heat exchanger and the expansion valve;
A bypass flow path for guiding the refrigerant discharged from the compressor to the upper space of the receiver by bypassing the outdoor heat exchanger;
Bypass refrigerant control means for controlling the refrigerant flow through the bypass flow path;
An air conditioner comprising: The bypass refrigerant control means causes the refrigerant discharged from the compressor to flow to the receiver via the bypass pipe when the amount of refrigerant flowing through the indoor heat exchanger is a predetermined value or less. The air conditioner according to claim 1. A plurality of the indoor heat exchangers are provided,
These indoor heat exchangers are connected to the outdoor heat exchanger by a low-pressure gas pipe, a high-pressure gas pipe, and a liquid pipe, respectively, and refrigerant is supplied from the liquid pipe during cooling operation and from the high-pressure gas pipe during heating operation. To exchange heat with indoor air,
The air conditioner according to claim 1 or 2, wherein the bypass refrigerant control means supplies the liquid refrigerant stored in the liquid receiver to the indoor heat exchanger side. A compressor for compressing the refrigerant;
An outdoor heat exchanger that is arranged outside and condenses the refrigerant compressed by the compressor during cooling operation;
An expansion valve for expanding the refrigerant condensed by the outdoor heat exchanger during cooling operation;
An indoor heat exchanger that is disposed indoors and that evaporates the refrigerant expanded by the expansion valve during cooling operation;
In a control method of an air conditioner comprising: a liquid receiver provided between the outdoor heat exchanger and the expansion valve;
When the amount of refrigerant flowing through the indoor heat exchanger is a predetermined value or less, the refrigerant discharged from the compressor is guided to the upper space of the liquid receiver by bypassing the outdoor heat exchanger. A control method for an air conditioner. A plurality of the indoor heat exchangers are provided,
These indoor heat exchangers are connected to the outdoor heat exchanger by a low-pressure gas pipe, a high-pressure gas pipe, and a liquid pipe, respectively, and refrigerant is supplied from the liquid pipe during cooling operation and from the high-pressure gas pipe during heating operation. To exchange heat with indoor air,
The method of controlling an air conditioner according to claim 4, wherein the liquid refrigerant stored in the liquid receiver is supplied to the indoor heat exchanger side. A plurality of the indoor heat exchangers are provided,
These indoor heat exchangers are respectively connected to the outdoor heat exchanger by a low pressure gas pipe, a high pressure gas pipe and a liquid pipe,
The low-pressure gas pipe is provided with an inlet-side pressure adjustment valve that performs pressure adjustment based on an inlet-side pressure with the indoor heat exchanger side as an upstream,
The air conditioner according to claim 1, wherein a refrigerant is supplied from the liquid pipe during cooling operation and from the high-pressure gas pipe during heating operation to exchange heat with room air.

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