JP2009024965A - Air conditioner - Google Patents

Abstract

[PROBLEMS] To reduce refrigerant passage noise at the start of heating operation of a dormant indoor unit regardless of the distribution of refrigerant in the gas-liquid two layers in the indoor heat exchanger of the dormant indoor unit in a multi-room air conditioner Let me.
An outdoor unit 100 including a compressor 110 and an outdoor heat exchanger 130, a plurality of indoor units 201 to 203 each having an indoor blower 211, an indoor heat exchanger 210, and an indoor side expansion valve 212; An indoor unit control unit 220 that monitors the units 201 to 203 and controls their operation state. In the air conditioners connected in parallel, in the heating operation mode, when a predetermined indoor unit starts the heating operation from the heating operation stopped state or the thermo-off state among the plurality of indoor units, from the start of the operation The liquid refrigerant accumulated in the indoor heat exchanger 210 is discharged at a stretch with the expansion valve 212 at a substantially maximum opening for a predetermined time.
[Selection] Figure 1

Description

  The present invention relates to an air conditioner in which a plurality of indoor units are connected to an outdoor unit. More specifically, among the plurality of indoor units, an indoor unit in a heating operation stop state or a thermo-off state is heated. The present invention relates to a technique for reducing refrigerant passing sound generated by an expansion valve when resuming operation.

  In an air conditioner (multi-room type multi air conditioner) that has multiple indoor units connected to an outdoor unit, each indoor unit can be controlled individually, and the remote control is turned off when air conditioning is not required. The operation is stopped by the signal, and when the room temperature reaches the set temperature, the thermo-off state is automatically set.

  In the present specification, an indoor unit that is in a sleep state or a sleep state including the operation stop state and the thermo-off state may be referred to as a sleep indoor unit. Further, in the sleep state, the indoor blower is stopped.

  In the reversible cycle air conditioner, in the cooling operation mode, the outdoor heat exchanger on the outdoor unit side functions as a condenser, and the indoor heat exchanger on the indoor unit side functions as an evaporator. On the other hand, in the heating operation mode, the outdoor heat exchanger acts as an evaporator, and the indoor heat exchanger acts as a condenser.

  Therefore, in the heating operation mode, when other indoor units are in the heating operation state, liquid refrigerant accumulates in the dormant indoor unit (sleeping indoor unit). FIG. 3 schematically shows a state in which liquid refrigerant is accumulated in the indoor heat exchanger 1 of the dormant indoor unit (a gas-liquid two-layer state).

  In order to prevent the liquid refrigerant from accumulating excessively, conventionally, the temperature difference between the indoor liquid pipe temperature by the indoor liquid pipe sensor 4 and the heat exchanger temperature by the heat exchanger temperature sensor 5 is monitored to collect the liquid refrigerant. The amount is estimated, and when the accumulated amount exceeds a predetermined value, the electronic expansion valve 2 is slightly opened to circulate the refrigerant. In the sleep state, the indoor blower (cross flow fan) 3 is stopped.

  However, according to this, the refrigerant also flows into the dormant indoor unit, resulting in unnecessary heating capability, and a problem that a refrigerant passing sound is generated due to the liquid refrigerant flowing through the electronic expansion valve 2 that is opened slightly. There is.

  In order to solve this problem, in the invention described in Patent Document 1, the electronic expansion valve of the dormant indoor unit is fully closed, and the average refrigerant temperature of the other indoor unit outlet being operated and the refrigerant temperature of the dormant indoor unit outlet are Based on the temperature difference and the discharge temperature of the compressor, the degree of accumulation of liquid refrigerant in the dormant indoor unit is determined. If the amount of accumulation is large, the electronic expansion valve is opened largely for a predetermined time to collect liquid refrigerant. ing.

  According to this, unnecessary heating capacity does not come out from the sleeping indoor unit, and no refrigerant passing sound is generated, but the refrigerant passing sound generated when starting the heating operation from the sleeping state is taken into consideration. There are still problems to be solved.

  That is, when starting the heating operation from the sleep state, conventionally, on the condition that the temperature of the indoor heat exchanger 1 is high, the indoor blower 3 is immediately put into an operation state when the heating operation restart signal is issued. The electronic expansion valve 2 is closed and slowly opened from a slight state.

  However, when the indoor blower 3 is operated while the electronic expansion valve 2 is closed, the gas refrigerant rapidly condenses in the indoor heat exchanger 1 and the liquid refrigerant accumulates excessively, and the upstream of the electronic expansion valve 2. Since both the downstream side and the downstream side are filled with the liquid refrigerant, a large refrigerant passing sound is generated.

  In the invention described in Patent Document 1, when the amount of liquid refrigerant accumulated in the dormant indoor unit increases, the electronic expansion valve opens widely for a predetermined time and liquid refrigerant is recovered. Since it is indefinite in time and is not necessarily output immediately after the recovery of the liquid refrigerant, depending on how the liquid refrigerant accumulates at that time, a loud refrigerant passing sound may be generated at the start of the heating operation.

JP 2000-88388 A

  Therefore, an object of the present invention is to provide an air conditioner in which a plurality of indoor units are connected to an outdoor unit, in what state the refrigerant distribution in the gas-liquid two layers in the indoor heat exchanger of the dormant indoor unit is. However, it is to reduce the refrigerant passing sound at the start of the heating operation of the dormant indoor unit.

  In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an outdoor unit including a compressor and an outdoor heat exchanger, and a plurality of indoor units each having an indoor fan, an indoor heat exchanger, and an indoor expansion valve. And an indoor unit control unit that monitors each indoor unit and controls the operation state thereof, and the plurality of indoor units are connected in parallel to the outdoor unit via liquid side pipes and gas side pipes. In the connected air conditioner, the indoor unit controller is configured to start the heating operation when the predetermined indoor unit among the plurality of indoor units starts the heating operation from the heating operation stop state or the thermo-off state in the heating operation mode. The expansion valve has a substantially maximum opening degree for a predetermined time from the start of operation.

  The invention according to claim 2 is the invention according to claim 1, wherein the indoor unit controller keeps the indoor blower in a stopped state while keeping the expansion valve at a substantially maximum opening degree for a predetermined time from the start of operation. It is characterized by that.

  According to the first aspect of the present invention, when the dormant indoor unit is in the heating operation, the liquid accumulated in the dormant indoor unit by setting the expansion valve to the maximum opening for a predetermined time from the start of the operation. Since the refrigerant flows through the expansion valve almost without any resistance and is collected to the outdoor unit at a stroke, the refrigerant passing sound can be kept low even if the sleeping indoor unit is heated from the sleeping state.

  Further, according to the invention of claim 2, the indoor heat exchanger of the sleep indoor unit is maintained while the expansion valve is kept at a substantially maximum opening degree for a predetermined time from the start of the heating operation. Since the condensation of the gas refrigerant hardly occurs, the effect in claim 1 can be made more reliable.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited to this. FIG. 1 is a schematic diagram showing an example of a refrigeration cycle provided in the air conditioner of the present invention, and FIG. 2 is a schematic diagram similar to FIG. 3 for explaining the operation of the present invention.

  As shown in FIG. 1, the air conditioner includes an outdoor unit 100 and an indoor unit 200. However, since the air conditioner is a multi-room air conditioner (multi air conditioner), the indoor unit 200 includes a plurality of units. Then, three indoor units 201, 202, and 203 are included. For the sake of explanation, when there is no need to distinguish between the indoor units 201, 202, and 203, the indoor unit 200 may be referred to as a generic term.

  The outdoor unit 100 is provided with a compressor 110, a four-way valve 120, an outdoor heat exchanger 130, an outdoor fan 131, an outdoor electronic expansion valve 140, and an accumulator 150. The outdoor unit 100 may be added as appropriate according to the capacity required on the indoor unit 200 side. The operation of the outdoor unit 100 is controlled by an outdoor unit control unit (not shown).

  The indoor units 201, 202, and 203 may have the same configuration, and include an indoor heat exchanger 210, an indoor blower 211, an indoor electronic expansion valve 212, a refrigerant temperature sensor 213, and a heat exchanger temperature sensor 214, respectively. Normally, a propeller fan is used for the outdoor blower 131, whereas a cross flow fan is used for the indoor blower 211.

  The indoor unit 200 is provided with an indoor unit control unit 220 that controls the indoor units 201, 202, and 203. The indoor unit control unit 220 determines the rotation speed of the indoor blower 211 and the indoor-side electronics based on a command signal from a remote controller (not shown), detected temperature signals output from the refrigerant temperature sensor 213 and the heat exchanger temperature sensor 214, and the like. The opening degree of the expansion valve 212 is controlled.

  The indoor units 201, 202, and 203 are connected in parallel to the outdoor unit 100 via the liquid side pipe 101 and the gas side pipe 102.

  In the heating operation mode, the four-way valve is switched to the state shown in the solid line, the refrigerant discharge side of the compressor 110 is connected to the gas side pipe 102, and the outdoor heat exchanger 130 is connected to the low pressure side including the accumulator 150.

  As a result, the high-temperature and high-pressure gas refrigerant discharged from the compressor 110 is supplied from the gas-side pipe 102 to the indoor units 201, 202, and 203, and heat is exchanged with indoor air in the indoor heat exchanger 210 to condense and liquefy. And the inside of the indoor heat exchanger 210 will be in a gas-liquid two-layer state.

  Thereafter, the circulation amount of the refrigerant is controlled to a predetermined value by passing through the indoor electronic expansion valve 212, sent to the outdoor unit 100 side via the liquid side pipe 101, depressurized by the outdoor electronic expansion valve 140, and outdoor heat exchange. After being vaporized and gasified in the vessel 130, it is returned to the compressor 110 through the accumulator 150.

  On the other hand, in the cooling operation mode, the four-way valve 120 is switched to the state of the chain line in the figure, the refrigerant discharge side of the compressor 110 is connected to the outdoor heat exchanger 130, and the gas side pipe 102 is connected to the low pressure side including the accumulator 150. Connected. Thereby, the outdoor heat exchanger 130 acts as a condenser, and the indoor heat exchanger 210 acts as an evaporator.

  In the heating operation mode, it is assumed that among the indoor units 201, 202, and 203, for example, the indoor unit 201 enters a sleep state in which the operation is stopped or the room temperature reaches a set temperature due to a remote control operation stop command and the thermostat is off. When the sleeping state is entered, the indoor blower 211 of the sleeping indoor unit is stopped and the indoor electronic expansion valve 212 is turned off.

  Since the indoor unit control unit 220 constantly monitors the remote control signal and the indoor unit 200, the indoor unit in the operating state (in this case, the indoor units 202 and 203) and the indoor unit that has entered the sleep state (this In this case, the indoor unit 201) can be identified.

  In the dormant indoor unit 201, the indoor-side electronic expansion valve 212 is closed, so that the condensed liquid refrigerant accumulates in the indoor heat exchanger 210. The accumulation amount of the liquid refrigerant is estimated by a temperature difference between the condensation temperature detected by the refrigerant temperature sensor 213 and the heat exchanger temperature detected by the heat exchanger temperature sensor 214.

  The indoor unit controller 220 monitors the amount of liquid refrigerant accumulated, and in this embodiment, the indoor side of the dormant indoor unit 201 prevents the liquid refrigerant from accumulating excessively in the indoor heat exchanger 210 of the dormant indoor unit 201. The electronic expansion valve 212 is opened slightly to circulate the refrigerant.

  Thus, even if the indoor electronic expansion valve 212 is opened slightly and the refrigerant is circulated, liquid refrigerant has accumulated in the indoor heat exchanger 210 to some extent (about 50% of the heat exchanger volume). This state is indicated by a one-dot chain line in the schematic diagram of FIG.

  When the sleeping indoor unit 201 is in such a state, when a heating operation command is issued by the remote controller or the thermo-off state is canceled, the indoor unit control unit 220 controls the sleeping indoor unit 201 as follows. .

  That is, when the heating operation of the dormant indoor unit 201 is started, the opening degree of the indoor electronic expansion valve is almost fully opened for a predetermined time (for example, about 1 minute) from the start of the heating operation, and is accumulated in the indoor heat exchanger 210 The liquid refrigerant that has been discharged is withdrawn at a stroke as shown by the arrow in FIG.

  During this time, it is preferable to stop the indoor blower 211 so that the gas refrigerant in the indoor heat exchanger 210 is condensed and liquid refrigerant is not added.

  In this way, after the liquid refrigerant that had accumulated in the indoor heat exchanger 210 was removed, the indoor blower 211 was started, and the opening degree of the indoor electronic expansion valve 212 was controlled to a predetermined value to be in a dormant state. Let indoor unit 201 be heating operation.

  According to this, since the upstream side and the downstream side of the indoor electronic expansion valve 212 are not liquid-sealed, it is possible to eliminate or greatly reduce the large refrigerant passing sound that has been generated at the start of the heating operation.

  In the dormant state, as in the invention described in Patent Document 1, when the indoor electronic expansion valve of the dormant indoor unit is fully closed, and the amount of liquid refrigerant in the dormant indoor unit increases. The liquid refrigerant may be recovered by opening the electronic expansion valve largely for a predetermined time, but even in such a case, according to the present invention, at the start of the heating operation, preferably the indoor fan is stopped, By making the indoor electronic expansion valve substantially fully open for a predetermined time, it is possible to eliminate or greatly reduce the refrigerant passing sound at the start of the heating operation.

The schematic diagram which shows an example of the refrigerating cycle with which the air conditioner of this invention is provided. The schematic diagram for demonstrating the effect | action of this invention. The schematic diagram which shows the state in which the liquid refrigerant has accumulated in the indoor heat exchanger of a dormant indoor unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Outdoor unit 101 Liquid side piping 102 Gas side piping 110 Compressor 120 Four-way valve 130 Outdoor heat exchanger 140 Outdoor electronic expansion valve 150 Accumulator 200 (201, 202, 203) Indoor unit 210 Indoor heat exchanger 211 Indoor fan 212 Room Inner electronic expansion valve 213 Refrigerant temperature sensor 214 Heat exchanger temperature sensor 220 Indoor unit controller

Claims (2)

An outdoor unit including a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor blower, an indoor heat exchanger, and an indoor expansion valve, and monitoring each indoor unit and controlling the operation state thereof An air conditioner including an indoor unit control unit, wherein the plurality of indoor units are connected in parallel to the outdoor unit via a liquid side pipe and a gas side pipe.
In the heating operation mode, the indoor unit control unit performs the expansion for a predetermined time from the start of operation when a predetermined indoor unit of the plurality of indoor units starts the heating operation from the heating operation stop state or the thermo-off state. An air conditioner characterized in that the valve has a substantially maximum opening.   2. The air conditioner according to claim 1, wherein the indoor unit controller keeps the indoor blower in a stopped state while keeping the expansion valve at a substantially maximum opening degree for a predetermined time from the start of operation.

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