JPH11173712A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which has mutually independent refrigeration cycle circuits and parallel indoor heat exchangers and common blower for feeding a warm air into a room through the heat exchangers and suppresses a cold air flowing in the room during defrosting. SOLUTION: During the heating operation of refrigeration cycle circuits, one of these circuits goes into the defrosting operation. For fixed time after end of this operation, control means inhibits the other refrigeration cycle circuits from the defrosting operation, thus inhibiting the continuous defrosting operation to avoid reducing the room air temp., this permitting the temp. difference between a set room temp. for the defrosting operation and actual room temp. to be reduced, compared with that in the conventional control permitting the continuous defrosting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an air conditioner in which a plurality of independently provided indoor heat exchangers of a refrigeration cycle circuit are arranged side by side, and a common blower blows air through each indoor heat exchanger. The present invention relates to an air conditioner that supplies air to a room, and particularly to an air conditioner that controls a defrosting operation without impairing the comfort of air conditioning.

[0002]

2. Description of the Related Art During a heating operation in an air conditioner, a phenomenon occurs in which frost adheres to an outdoor heat exchanger. In order to remove the adhering frost, high-temperature refrigerant discharged from a compressor is subjected to outdoor heat exchange. It is necessary to perform a defrosting operation in which the frost is melted by flowing into a vessel. However, in the refrigeration cycle circuit during the defrosting operation, since low-temperature refrigerant is guided to the indoor heat exchanger, there is a problem that indoor air is cooled and the room temperature is lowered.

Here, in a so-called multi-chamber air conditioner in which the outdoor heat exchangers of a plurality of independent refrigeration cycle circuits are integrated, since the outdoor heat exchanger is shared, a plurality of the outdoor heat exchangers are used. It is necessary to perform the defrosting operation simultaneously in an independent refrigeration cycle circuit.
As described in JP-A-46-46, by performing an accurate defrosting operation based on a difference in the operating state of each independent refrigeration cycle circuit, the time of the defrosting operation is shortened, and a decrease in room temperature is suppressed.

By the way, as described in, for example, JP-A-3-79963, a plurality of independent indoor heat exchangers of a refrigeration cycle circuit are arranged side by side, and a common blower is connected through these indoor heat exchangers. In the air conditioner that is blown by the air conditioner, since the indoor heat exchanger is integrated, a defrosting operation method different from the above multi-room air conditioner is required. .

Therefore, conventionally, generally, when a plurality of independent refrigeration cycle circuits simultaneously reach the defrosting condition,
For example, in an air conditioner having independent first and second refrigeration cycles, if the first and second refrigeration cycle circuits simultaneously reach the defrosting condition, one of the refrigeration cycle circuits, for example, the first refrigeration cycle Only the cycle circuit starts the defrosting operation, while the second refrigeration cycle circuit continues the heating operation, and continues the defrosting operation of the second refrigeration cycle circuit at the end of the defrosting operation of the first refrigeration cycle circuit. To start. Also, when the second refrigeration cycle circuit reaches the defrosting condition during the defrosting operation of the first refrigeration cycle circuit, similarly, when the defrosting operation of the first refrigeration cycle circuit ends, the second refrigeration cycle circuit continuously performs the defrosting operation. The defrosting operation of the refrigeration cycle circuit 2 is started. This is because the indoor heat exchangers of the first and second refrigeration cycle circuits that are independent of each other are arranged side by side and the blower is shared, so that the indoor air is removed by the defrosting operation of one of the refrigeration cycle circuits. This is because the cooling is eased by the heating operation of the other refrigeration cycle circuit.

In the above air conditioner, when the cooling and heating loads to be air-conditioned are small, the operation of one refrigeration cycle circuit, for example, the second refrigeration cycle circuit is stopped, and the first refrigeration cycle circuit is stopped. In general, the capacity control of the cooling and heating capacities is performed by operating only the operation. In the case of the capacity control during the heating operation, for example, the first control is performed.
When the first refrigeration cycle circuit starts the defrosting operation when only the refrigeration cycle is operated, by simultaneously starting the heating operation of the stopped second refrigeration cycle circuit, the first refrigeration cycle circuit starts the defrosting operation. A decrease in the heating capacity due to the defrosting operation of the refrigeration cycle circuit is compensated for by the second refrigeration cycle circuit.

[0007] The low-temperature refrigerant sucked into the compressor of the first refrigeration cycle circuit during the defrosting operation and the second refrigerant during the heating operation.
A part of the high-temperature refrigerant discharged from the compressor of the refrigeration cycle circuit is directly subjected to heat exchange, thereby raising the temperature of the refrigerant sucked into the compressor of the first refrigeration cycle circuit, thereby increasing the temperature of the first refrigeration cycle. In some cases, the time of the defrosting operation is shortened by increasing the capacity of the compressor in the cycle circuit, and the decrease in the room temperature is suppressed.

The multi-room cooling / heating apparatus described in Japanese Patent Application Laid-Open No. 5-71833 comprises a plurality of heat source side refrigerant cycles and a plurality of utilization side refrigerant cycles. In this multi-room cooling / heating apparatus, one heat source side refrigerant cycle is provided. Ends the defrosting operation and starts the heating operation, so that the start of the defrosting operation of another heat source side cycle is controlled to be delayed for a certain time.

[0009]

However, during the defrosting operation, one of the refrigeration cycles performs the heating operation, but the other refrigeration cycle circuit cools the indoor air by the defrosting operation. And the indoor air temperature is inevitably reduced. Further, as described above, after the defrosting operation of one of the refrigeration cycle circuits is completed, the defrosting operation of the other refrigeration cycle circuit is continuously started, so that the indoor air temperature is reduced. The decrease in the amount becomes significant.

Further, for example, when the first refrigeration cycle circuit ends the defrosting operation and starts the heating operation, and at the same time, the second refrigeration cycle circuit starts the defrosting operation, the first refrigeration cycle circuit is removed. The indoor air cooled by the frost operation is further cooled by the defrosting operation of the second refrigeration cycle circuit, and is sucked into the indoor heat exchanger of the first refrigeration cycle circuit. When the indoor heat exchanger is shared by the first and second refrigeration cycle circuits, the high-temperature and high-pressure refrigerant of the first refrigeration cycle circuit and the second refrigeration cycle are used in these indoor heat exchangers. Heat is exchanged with the low-temperature low-pressure refrigerant in the circuit. Therefore, in the indoor heat exchanger of the first refrigeration cycle circuit during the heating operation, the amount of heat exchange becomes excessive, so that the high-pressure side pressure decreases, and the liquid tends to return to the compressor.

Further, for example, the first refrigeration cycle circuit starts the defrosting operation, and the second refrigeration cycle circuit starts the second refrigeration cycle circuit in order to alleviate the decrease in the heating capacity.
Heating operation of the refrigeration cycle circuit is started, but sufficient heating capacity cannot be obtained because one of the refrigeration cycle circuits is in a defrosting operation, and furthermore, a feeling of cool air due to a decrease in blown air temperature often causes a problem.

In the heating operation, for example, when only the first refrigeration cycle circuit is operated, the heating load of the object to be air-conditioned is small, and thus the capacity of the indoor heat exchanger and the air flow rate passing through the indoor heat exchanger. Is often excessively large, both the high-pressure side pressure and the low-pressure side pressure decrease, and the temperature of the refrigerant also decreases. On the other hand, it is common to start the defrosting operation when the temperature of the refrigerant at a predetermined position in the refrigeration cycle circuit becomes equal to or lower than a predetermined value. However, as described above, only one of the refrigeration cycle circuits performs the heating operation. In this case, since the temperature of the refrigerant is likely to decrease, there is also a problem that the defrosting operation is easily started even when the frost state of the outdoor heat exchanger is actually light.

Further, for example, of the low-temperature refrigerant drawn into the compressor in the first refrigeration cycle circuit during the defrosting operation and the high-temperature refrigerant from the compressor in the second refrigeration cycle circuit during the heating operation, In the case where a part is directly subjected to heat exchange, the second refrigeration cycle circuit has a problem in that the amount of refrigerant provided for the heating operation itself is reduced, so that the heating capacity is reduced. There was a problem that it became expensive by becoming complicated.

The present invention has been made in order to solve such a problem, and has a plurality of independent refrigeration cycle circuits, arranges the indoor heat exchangers side by side, and uses a common blower for each room. An air conditioner that blows air through the inner heat exchanger and supplies it to the room. It suppresses the decrease in indoor temperature when performing defrosting operation, and also removes air from the outside heat exchanger appropriately in accordance with the frosting condition. It is an object of the present invention to provide an air conditioner that performs a frost operation and prevents a refrigerant liquid from returning to a compressor due to a defrost operation.

[0015]

To achieve the above object, a first air conditioner of the present invention comprises a compressor, a four-way switching valve, an outdoor heat exchanger, a throttle device, an indoor heat exchanger, A plurality of independent refrigeration cycle circuits each having an accumulator connected sequentially by refrigerant pipes are provided, and indoor heat exchangers of each refrigeration cycle circuit are arranged side by side, and air is commonly blown through each indoor heat exchanger. In each refrigeration cycle circuit, high-temperature gas refrigerant is liquefied in the indoor heat exchanger and liquid refrigerant is evaporated in the outdoor heat exchanger. After reaching the defrosting conditions (determined based on the outdoor air temperature, refrigerant temperature, operation time, etc.), the outdoor heat exchanger liquefies the high-temperature gas refrigerant and the indoor heat exchanger evaporates the liquid refrigerant. Operating and each refrigeration cycle If the defrost cycle from the start of the defrosting operation to the start of the next defrosting operation is less than the predetermined time on the road alone, the defrosting operation is prohibited, and the simultaneous defrosting operation of a plurality of refrigeration cycle circuits is prohibited. Control means for prohibiting the defrosting operation of another refrigeration cycle circuit for a certain period of time after one refrigeration cycle circuit enters a defrosting operation while each refrigeration cycle circuit is in a heating operation and ends. Is provided.

By providing such control means,
An extreme decrease in the indoor air temperature after the defrosting operation can be suppressed, and the comfort of air conditioning is not impaired.

In the second air conditioner of the present invention, the "first operation of the refrigerating cycle circuit after the defrosting operation of one refrigerating cycle circuit is prohibited for a predetermined time after the defrosting operation of the other refrigerating cycle circuit". Instead, after the defrosting operation of one refrigeration cycle circuit, the other refrigeration cycle circuits are removed until the difference between the indoor air temperature sucked into the indoor unit side heat exchanger and the set value of the indoor air temperature becomes equal to or less than a predetermined value. The frost operation is prohibited.

By such control, an extremely low indoor air temperature after the defrosting operation can be suppressed, and the comfort of air conditioning is not impaired.

Further, the third air conditioner of the present invention comprises a plurality of independent refrigeration cycle circuits, a single blower common to each indoor heat exchanger, a defrost cycle of the refrigeration cycle circuit alone, The first air conditioner is the same as the first air conditioner in that simultaneous defrosting of the refrigeration cycle circuit is prohibited, and when one refrigeration cycle circuit performs heating operation and the other refrigeration cycle circuit is stopped, one refrigeration cycle circuit is stopped. When the refrigeration cycle circuit reached the defrosting condition, one refrigeration cycle circuit was prohibited from entering the defrosting operation for a fixed time, and one of the other refrigeration cycle circuits was heated and operated for a certain time. At a point in time, it is determined whether or not one of the refrigeration cycle circuits has reached the defrosting condition again, and if it has reached the defrosting condition, control means for starting the defrosting operation of one of the refrigeration cycle circuits is provided.

This third air conditioner controls the capacity of the heating capacity by increasing or decreasing the number of refrigeration cycle circuits operated according to the magnitude of the heating load to be air-conditioned. Sometimes, by performing the heating operation of one of the other refrigeration cycle circuits before performing the defrost operation of the refrigeration cycle circuit, it is possible to reduce the feeling of cool air due to the defrost operation of one refrigeration cycle circuit, Unnecessary defrosting operation due to a decrease in pressure in the refrigeration cycle circuit can be prevented. Incidentally, a decrease in the pressure in the refrigeration cycle circuit is a decrease in the temperature, and the air conditioner may erroneously enter the defrosting operation due to the decrease in the temperature.

Further, the fourth air conditioner according to the present invention is characterized in that “when a certain time has elapsed,
Instead of again determining whether one refrigeration cycle circuit has reached the defrosting condition, when the difference between the indoor air temperature sucked into the indoor unit side heat exchanger and the set value of the indoor air temperature becomes equal to or less than a predetermined value. , Determine again if one refrigeration cycle circuit has reached the defrost condition, and if the defrost condition has been reached,
Similarly to the third air conditioner, the control is performed to start the defrosting operation of the one refrigeration cycle circuit.

Therefore, according to the fourth air conditioner, similarly to the third air conditioner, the feeling of cool air due to the defrosting operation of one refrigeration cycle circuit can be reduced, and the inside of the refrigeration cycle circuit during small capacity operation can be reduced. Unnecessary defrosting operation due to a decrease in the pressure of the fuel cell can be prevented.

The fifth air conditioner of the present invention performs a heating operation and a defrosting operation in that it includes a plurality of refrigeration cycle circuits and a single blower that blows air in common through each indoor heat exchanger. The points are the same as the first air conditioner,
And an air conditioner that controls so as to prohibit simultaneous defrosting operation of each refrigeration cycle circuit, wherein one refrigeration cycle circuit performs a heating operation and another refrigeration cycle circuit is stopped when one refrigeration cycle circuit is stopped. When the refrigerating cycle circuit reaches the defrosting condition, the refrigerating cycle circuit prohibits one refrigerating cycle circuit from entering the defrosting operation for a fixed time and the refrigerant discharge amount of the compressor of one refrigerating cycle circuit is kept constant. The heating operation is performed with the amount increased, and after a certain period of time, it is determined again whether one refrigeration cycle circuit has reached the defrost condition, and if the defrost condition has been reached, the defrost operation of one refrigeration cycle circuit is started and It is characterized by having control means for starting a heating operation of another refrigeration cycle.

According to the fifth air conditioner, it is determined again whether or not the refrigeration cycle circuit during the heating operation has reached the defrosting condition. No need to operate, thus preventing frequent start / stop of the compressor, preventing excessive overheating due to sudden increase in heating capacity that would otherwise occur when other refrigeration cycles are not required, and cooling air by defrosting operation It is possible to alleviate the feeling, inhibit continuous defrosting operation, suppress an extremely low indoor air temperature, and perform air conditioning to obtain a constant indoor air temperature. In this air conditioner,
The compressor of each refrigeration cycle circuit is provided with a means for controlling the capacity (for example, an inverter, a pole number converter, an unloader, etc.).

Further, the sixth air conditioner according to the present invention provides the fifth air conditioner, wherein “when a certain time has passed,
Instead of again determining whether one refrigeration cycle circuit has reached the defrosting condition, when the difference between the indoor air temperature sucked into the indoor unit side heat exchanger and the set value of the indoor air temperature becomes equal to or less than a predetermined value. , Determine again if one refrigeration cycle circuit has reached the defrost condition, and if the defrost condition has been reached,
Similarly to the fifth air conditioner, control is performed so that the defrosting operation of the one refrigeration cycle circuit is started and the heating operation of the other refrigeration cycle is started.

Therefore, according to the sixth air conditioner, similarly to the fifth air conditioner, it is determined again whether or not the refrigeration cycle circuit during the heating operation has reached the defrosting condition. Without the need to run other stopped refrigeration cycle circuits, thus frequent compressor operation /
It can prevent stoppage, prevent excessive overheating due to a sudden increase in heating capacity, reduce the feeling of cool air due to defrosting operation, prohibit continuous defrosting operation, and suppress extreme drop in indoor air temperature Thus, air conditioning that obtains a constant indoor air temperature can be performed.

In each of the first to sixth air conditioners, it is preferable that the refrigeration cycle circuit for which the defrosting operation has been completed be continuously heated for a certain period of time after the completion. By continuing the heating operation for a certain period of time without stopping the refrigeration cycle circuit that has completed the defrosting operation regardless of the set value of the indoor air temperature, the compressor discharge side pressure of the refrigeration cycle circuit is reduced. To prevent the refrigerant liquid from returning to the compressor at the time of stopping after the completion of the defrosting.

[0028]

Embodiment 1 FIG. 1 is a refrigeration cycle system diagram of an air conditioner according to Embodiment 1 of the present invention. This air conditioner includes a plurality of (two in this case) independent refrigeration cycle circuits.

As shown in FIG. 1, the first of the two refrigeration cycle circuits (a) includes a compressor (1a) to a four-way switching valve (2a),
Outdoor heat exchanger (3a), expansion device acting as expansion mechanism
(4a) (e.g., a capillary tube, an electronic expansion valve, etc.), sequentially connected to the four-way switching valve (2a) through the indoor heat exchanger (5) to the four-way switching valve (2a), and further from the four-way valve (2a) to the accumulator (6a)
And an outdoor blower (7a) configured to connect to the outdoor heat exchanger (3a) by a refrigerant pipe so as to return to the compressor (1a). Similarly, the second refrigeration cycle circuit (b) of the two is provided with a four-way switching valve from the compressor (1b).
(2b), the outdoor heat exchanger (3b), the expansion device (4b), the indoor heat exchanger (5), and sequentially connected to the four-way switching valve (2b) through the refrigerant pipe, and further from the four-way valve (2b). An outdoor blower (7b) is provided which is connected by a refrigerant pipe so as to return to the compressor (1b) through the accumulator (6b), and blows air to the outdoor heat exchanger (3b). Here, the indoor-side heat exchanger (5) includes a common blower (8) that arranges and arranges the coils of the indoor-side heat exchangers of the first and second refrigeration cycles and sends air through both coils. .

The operation of the air conditioner having the above configuration will be described with reference to the first refrigeration cycle circuit (a). During the cooling operation, the compressor (1
The high-temperature and high-pressure refrigerant discharged from a) passes through the four-way switching valve (2a) and condenses in the outdoor heat exchanger (3a) to become a liquid refrigerant, adiabatically expands in the expansion device (4a), and performs indoor heat exchange. Evaporated in the vessel (5) to become gas refrigerant, four-way switching valve (2a), accumulator (6a)
And returns to the compressor (1a). At this time, the indoor heat exchanger (5)
Cool air is supplied from the room to the room. On the other hand, during the heating operation, by switching the four-way switching valve (2a) to the heating operation side, as indicated by the arrow indicated by the broken line in the figure, the high-temperature and high-pressure refrigerant discharged from the compressor (1a) becomes the four-way switching valve ( After passing through 2a), it is condensed in the indoor heat exchanger (5) to become a liquid refrigerant, adiabatically expanded in the expansion device (4a), evaporated in the outdoor heat exchanger (3a) to become a gas refrigerant, and is a four-way switching valve. (2a), and returns to the compressor (1a) via the accumulator (6a). At this time, warm air is supplied indoors from the indoor heat exchanger (5).

When the above-mentioned heating operation is continued,
For example, when the outdoor air temperature decreases, frost adheres to the outdoor heat exchanger (3a). When such frost increases, the efficiency of the outdoor heat exchanger deteriorates, and the amount of heat taken from the outdoor air decreases, so that the heating capacity of the air conditioner significantly decreases. Therefore, in such a case, a defrosting operation for removing frost is required.

During such a defrosting operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor (1a) is supplied to the four-way switching valve (2a) as indicated by the solid-line arrow in the drawing similarly to the cooling operation. And flows into the outdoor heat exchanger (3a). Here, the outdoor blower (7a) is stopped. Then, the frost adhering to the outdoor heat exchanger (3a) is melted by the high-temperature gas refrigerant, and the refrigerant follows the same path as in the cooling operation as shown in FIG.
The refrigerating cycle circuit that returns to the above is formed. The second refrigeration cycle circuit (b) performs cooling, heating, and defrosting operations in the same manner as the first refrigeration cycle circuit (a), and a description thereof will be omitted.

FIG. 2 shows a control flow chart of the air conditioner of the first embodiment, and FIG. 3 shows the heating operation and the defrosting operation of the air conditioner of the first embodiment in time. . Each of the refrigeration cycle circuits (a) and (b) alone prohibits the defrosting operation when the defrost cycle P from the defrosting operation start time to the next defrosting operation start time is less than a predetermined time. Control means is provided. When both the refrigeration cycle circuits (a) and (b) perform the defrosting operation, the defrosting operation is started with priority given to only one of the units. For example, the time from when the first refrigeration cycle circuit (a) starts the defrosting operation to when the second refrigeration cycle circuit (b) starts the defrosting operation is determined by the defrost cycle P. (2 in Embodiment 1A)
If the value is less than the value obtained by dividing by, control means for inhibiting the start of the defrosting operation of the second refrigeration cycle circuit (b) is provided.
In the air conditioning apparatus having the number N of refrigeration cycle circuits, the minimum pitch of the defrosting time is P / N.

FIG. 4 is a graph comparing the relationship between the operation time t and the room temperature T of the air conditioner of the first embodiment with that of the prior art. FIG. 4A shows the relationship between the operating time t and the room temperature T in Embodiment 1 in which intermittent defrosting is performed, and FIG. 4B shows another refrigeration cycle after the end of the defrosting operation in one refrigeration cycle. The relationship in the prior art which permits the start of a cycle defrosting operation is shown. In the related art, each refrigeration cycle circuit may continuously enter the defrosting operation, and the difference b1 between the room temperature set value and the room temperature at this time increases. However, according to the first embodiment, each refrigeration cycle circuit The circuit can be prevented from continuously entering the defrosting operation, and the difference a1 between the room temperature set value and the room temperature can be significantly reduced.

<Embodiment 2> An air conditioner according to Embodiment 2 includes a temperature detector (10) for detecting the indoor air temperature, as shown in the refrigeration cycle system diagram of the air conditioner in FIG.
A controller (9) is provided for controlling the operation and stop of each refrigeration cycle according to the target value of the indoor air temperature (referred to as room temperature set value) set in the controller (9). In this control, instead of limiting the start of the defrosting operation by time as in the first embodiment, for example, as in the control flowchart of the air conditioner shown in FIG.
After the defrosting operation of (a), the second refrigeration cycle circuit is operated until the difference between the room temperature set value and the indoor suction air temperature becomes equal to or less than a certain value.
(b) The defrosting operation is prohibited, and the heating operation is continued. As described above, similarly to the first embodiment, each refrigeration cycle circuit can be prevented from continuously entering the defrosting operation, and the difference between the room temperature set value and the room temperature can be significantly reduced.

<Third Embodiment> FIG. 6 is a control flowchart of the air conditioner of the third embodiment. In the air conditioner having the same configuration as that of the first embodiment, the heating load of the object to be air-conditioned is small during the heating operation, for example, the first refrigeration cycle circuit (a) is operating, and the second refrigeration cycle circuit (b) Is stopped, when the first refrigeration cycle circuit (a) in operation reaches the defrosting condition, the first refrigeration cycle circuit (a) is set to enter the defrosting operation for a certain period of time. Only, the heating operation is continued, and at the same time, the room temperature is raised by heating the second refrigeration cycle circuit (b) for a certain period of time, and then the first refrigeration cycle circuit ( It is determined again whether or not the condition a) has continuously reached the defrosting condition.
Start the defrosting operation of the refrigeration cycle circuit (a), if the defrosting condition has not been reached, return to normal operation, that is,
Heating operation of the first refrigeration cycle circuit (a) is continued;
Control means for stopping the operation of the refrigeration cycle circuit (b).

FIG. 7 shows a comparison between the operation time t and the room temperature T of the air conditioner of the third embodiment in comparison with the prior art. FIG. 7A shows the relationship between the operation time t and the room temperature T in the third embodiment before the defrosting operation, and FIG. 4B shows the related art in which each refrigeration cycle is allowed to continuously perform the defrosting operation. Shows the relationship in. In the prior art, a second refrigeration cycle circuit
When the operation of the first refrigeration cycle circuit (a) reaches the defrosting condition while the operation of (b) is stopped, the first refrigeration cycle circuit (a) enters the defrosting operation as it is. At the same time, the second refrigeration cycle circuit (b) starts the heating operation, but the difference b2 between the room temperature set value and the room temperature becomes large due to a decrease in the heating capacity due to the defrosting operation. According to 3, forcibly performing the heating operation of the two refrigeration cycle circuits before the defrosting operation is started, the difference a2 between the room temperature set value and the room temperature can be significantly reduced. Further, unnecessary defrosting operation due to a decrease in pressure in the refrigeration cycle circuit during small-capacity operation is prevented. Incidentally, a decrease in the pressure in the refrigeration cycle circuit is a decrease in the temperature, and the air conditioner may erroneously enter the defrosting operation due to the decrease in the temperature.

<Fourth Embodiment> An air conditioner according to a fourth embodiment has a temperature detector (10) for detecting the indoor air temperature, as shown in the refrigeration cycle system diagram of the air conditioner in FIG.
A controller (9) for controlling the number of operating refrigeration cycles based on the room temperature set value is provided. In this air conditioner, instead of limiting the start of the defrosting operation by time as in Embodiment 3, when the first refrigeration cycle circuit (a) in operation reaches the defrosting condition, As shown in the control flowchart of the air conditioner shown in FIG. 8, the first refrigeration cycle circuit (a) is prohibited from entering the defrosting operation and the heating operation is continued, and at the same time, the second refrigeration cycle circuit (b) is When the heating operation is performed and the difference between the room temperature set value and the indoor suction air temperature becomes equal to or less than a predetermined value, it is determined again whether the first refrigeration cycle circuit (a) has reached the defrosting condition, and the defrosting condition has been reached. If so, the defrosting operation of the first refrigeration cycle circuit (a) is started while the second refrigeration cycle circuit (b) is in the heating operation, and if the defrosting condition is not reached, the operation returns to the normal operation. That is, the heating operation of the first refrigeration cycle circuit (a) is continued and the second refrigeration cycle Providing a control means for stopping the operation of the road (b).

As described above, as in the third embodiment, by forcibly heating the two refrigeration cycle circuits before starting the defrosting operation, the difference between the room temperature set value and the room temperature can be greatly reduced. Can be. Further, unnecessary defrosting operation due to a decrease in pressure in the refrigeration cycle circuit during small-capacity operation is prevented.

<Fifth Embodiment> An air conditioner according to a fifth embodiment is composed of two refrigeration cycles as shown in FIG. 1, and the compressor (1a) and (1b) increase or decrease the refrigerant discharge amount. Means (for example, an inverter, a pole number converter, an unloader, and the like) are provided.

In the control of this air conditioner, the heating load of the object to be air-conditioned is small, for example, the first refrigeration cycle circuit (a)
Is a defrosting operation control when the second refrigeration cycle circuit (b) is stopped during operation. In this air conditioner,
As shown in the control flowchart of FIG. 9, when the heating operation is performed in a state where the refrigerant discharge amount of the compressor 1a of the first refrigeration cycle circuit (a) is reduced, when the defrosting condition is reached, At the same time, the refrigeration cycle circuit (a) prohibits the refrigeration cycle circuit 1a from entering the defrosting operation for a certain period of time, and performs the heating operation by increasing the refrigerant discharge amount of the compressor 1a by a certain amount for the certain period of time. ) Is again determined whether the condition has reached the defrosting condition, and if the condition has been reached, the refrigeration cycle circuit
Refrigeration cycle circuit (b) at the same time as starting the defrosting operation of (a)
Heating operation is started, and if the defrosting condition is not reached, the operation returns to the normal operation, that is, the first refrigeration cycle circuit
A control means for reducing the refrigerant discharge amount of the compressor (1a) in (a) and continuing the heating operation is provided. From the above, the frequent compressor by operating the stopped refrigeration cycle circuit (b)
(1b) Prevent the start and stop of the operation. Further, similarly to the above embodiment, when the defrosting condition is reached, 2
By performing the heating operation of the two refrigeration cycle circuits (a) and (b), the difference between the set room temperature and the room temperature can be significantly reduced. Further, unnecessary defrosting operation due to a decrease in pressure in the refrigeration cycle circuit during small-capacity operation is prevented.

Embodiment 6 The air conditioner of Embodiment 6 is provided with a compressor whose capacity can be controlled like the air conditioner of Embodiment 5, and the refrigeration cycle of the air conditioner of FIG. As shown in the system diagram, a temperature detector (10) for detecting the indoor air temperature and a controller (9) for controlling the operation and stop of each refrigeration cycle circuit according to the set indoor air temperature target value are provided. ing. This air conditioner does not limit the start of the defrosting operation according to the time as in the fifth embodiment. When the first refrigeration cycle circuit (a) in operation reaches the defrosting condition as shown in FIG. As shown in the control flowchart of the air conditioner, the first refrigeration cycle circuit (a) is prohibited from entering the defrosting operation, and at the same time, the refrigerant discharge amount of the compressor (1a) is increased by a certain amount to perform the heating operation. When the difference between the indoor suction air temperature and the target value of the indoor air temperature becomes equal to or more than a certain value, it is determined again whether the first refrigeration cycle circuit (a) has reached the defrosting condition, If the condition is reached the first
Heating operation of the refrigeration cycle circuit (b) is started simultaneously with the start of the defrosting operation of the refrigeration cycle circuit (a), and if the defrosting condition is not reached, the operation returns to the normal operation, that is, the first refrigeration cycle Control means is provided for continuing the heating operation by reducing the refrigerant discharge amount of the compressor 1a of the cycle circuit (a) as before.
As described above, frequent start and stop of the operation of the compressor (1b) due to the operation of the stopped refrigeration cycle circuit (b) are prevented. Further, similarly to the above-described embodiment, when the defrosting condition is reached, the two refrigeration cycle circuits (a) and (b) are forcibly heated to perform a heating operation, thereby greatly reducing the difference between the room temperature set value and the room temperature. can do. Further, unnecessary defrosting operation due to a decrease in pressure in the refrigeration cycle circuit during small-capacity operation is prevented.

<Embodiment 7> Also, as shown in the refrigeration cycle system diagram of the air conditioner of FIG. 1, the number of refrigeration cycles operated by a temperature detector (10) for detecting the indoor air temperature and a room temperature set value. A controller (9) for controlling the refrigeration cycle is provided, and the defrosting operation is started as in each of Embodiments 1 to 6, and the refrigeration cycle after the end of the defrosting operation is not stopped by controlling the number of operating refrigeration cycles, By providing the control means for continuing the heating operation for a certain period of time or more, it is possible to increase the compressor discharge side pressure of the refrigeration cycle after the defrost is completed, and to prevent the refrigerant liquid from returning to the compressor when stopping after the defrost is completed. .

[0044]

According to the present invention, there is provided an air conditioner having a plurality of independent refrigeration cycle circuits, arranging indoor heat exchangers, and blowing warm air from one common blower to the room. The following effects are obtained.

During the heating operation of the plurality of refrigeration cycle circuits,
One refrigeration cycle circuit performs a defrosting operation, and from the end, until a certain time elapses, or until the difference between the room temperature set temperature and the room temperature measurement value becomes a certain value or less,
By controlling the defrosting operation of the other refrigeration cycle circuits to be prohibited, the decrease in the indoor air temperature can be reduced.

When one of the refrigeration cycle circuits reaches the defrosting condition during the heating operation because the heating load is small, the defrosting operation is prohibited, and one of the other refrigeration cycle circuits is operated to keep the defrosting operation constant. After a time, or when the difference between the room temperature set temperature and the room temperature measurement value becomes equal to or less than a certain value, it is determined whether or not the one refrigeration cycle circuit has reached the defrosting condition. By controlling to perform the defrosting operation of the refrigeration cycle circuit, it is possible to reduce the decrease in the indoor air temperature, and unnecessary defrosting operation due to the decrease in the pressure in the refrigeration cycle circuit during the small capacity operation. Can be prevented.

When one of the refrigeration cycle circuits reaches the defrosting condition during the heating operation due to a small heating load, the defrosting operation is prohibited and the discharge amount of the compressor of the one refrigeration cycle circuit is reduced. Increase the heating operation, after a certain period of time, or when the difference between the room temperature set temperature and the room temperature measurement value is less than or equal to a certain value, determine whether the one refrigeration cycle circuit has reached the defrosting condition, If this is the case, by controlling the defrosting operation of the one refrigeration cycle circuit, it is possible to reduce the decrease in the indoor air temperature, and to reduce the pressure in the refrigeration cycle circuit during the small capacity operation. In addition to preventing unnecessary defrosting operation, it is possible to prevent frequent start / stop of the compressor due to operation of another stopped refrigeration cycle circuit.

Further, by controlling the refrigeration cycle circuit in which the defrosting operation has been performed to perform the heating operation for a certain period of time, it is possible to prevent the refrigerant liquid from returning to the compressor.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle system diagram of an air conditioner according to Embodiment 1 of the present invention.

FIG. 2 is a control flowchart of the air-conditioning apparatus according to Embodiment 1.

FIG. 3 is an operation graph of a heating operation and a defrosting operation in the first embodiment.

FIG. 4 is a diagram showing an operation time-room temperature graph in the first embodiment in comparison with a conventional technology.

FIG. 5 is a control flowchart of the air-conditioning apparatus according to Embodiment 2.

FIG. 6 is a control flowchart of the air-conditioning apparatus according to Embodiment 3.

FIG. 7 is a diagram showing an operation time-room temperature graph in the third embodiment in comparison with a conventional technology.

FIG. 8 is a control flowchart of the air-conditioning apparatus according to Embodiment 4.

FIG. 9 is a control flowchart of the air-conditioning apparatus according to Embodiment 5.

FIG. 10 is a control flowchart of the air-conditioning apparatus according to Embodiment 6.

[Explanation of symbols]

 a first refrigeration cycle circuit b second refrigeration cycle circuit 1a, 1b compressor 2a, 2b four-way switching valve 3a, 3b outdoor heat exchanger 4a, 4b expansion device 5 indoor heat exchanger 6a, 6b accumulator 7a, 7b Outdoor blower 8a, 8b Indoor blower 9 Controller 10 Indoor air temperature detector

Claims (7)

[Claims] 1. A compressor, a four-way switching valve, an outdoor heat exchanger,
A plurality of independent refrigeration cycle circuits each having an expansion device, an indoor-side heat exchanger, and an accumulator sequentially connected by refrigerant pipes, and an indoor-side heat exchanger of each refrigeration cycle circuit arranged side by side; A single blower that blows air in common through the heat exchanger; and in each refrigeration cycle circuit, the indoor heat exchanger liquefies the high-temperature gas refrigerant and the outdoor heat exchanger evaporates the liquid refrigerant. Defrosting occurs in the outer heat exchanger, and after reaching the defrosting condition, a defrosting operation of liquefying the high-temperature gas refrigerant in the outdoor heat exchanger and evaporating the liquid refrigerant in the indoor heat exchanger is performed, and In the refrigeration cycle circuit alone, if the defrost cycle from the start of the defrost operation to the start of the next defrost operation is less than the predetermined time, the defrost operation is prohibited, and the simultaneous defrost operation of multiple refrigeration cycle circuits is prohibited. Air conditioning to control In one embodiment, control means is provided for prohibiting the defrosting operation of another refrigeration cycle circuit for a certain period of time after one refrigeration cycle circuit enters and ends the defrosting operation while each refrigeration cycle circuit is in the heating operation. An air conditioner characterized by: 2. A compressor, a four-way switching valve, an outdoor heat exchanger,
A plurality of independent refrigeration cycle circuits each having an expansion device, an indoor-side heat exchanger, and an accumulator sequentially connected by refrigerant pipes, and an indoor-side heat exchanger of each refrigeration cycle circuit arranged side by side; A single blower that blows air in common through the heat exchanger; and in each refrigeration cycle circuit, the indoor heat exchanger liquefies the high-temperature gas refrigerant and the outdoor heat exchanger evaporates the liquid refrigerant. Defrosting occurs in the outer heat exchanger, and after reaching the defrosting condition, a defrosting operation of liquefying the high-temperature gas refrigerant in the outdoor heat exchanger and evaporating the liquid refrigerant in the indoor heat exchanger is performed, and In the refrigeration cycle circuit alone, if the defrost cycle from the start of the defrost operation to the start of the next defrost operation is less than the predetermined time, the defrost operation is prohibited, and the simultaneous defrost operation of multiple refrigeration cycle circuits is prohibited. Air conditioning to control During the heating operation of each refrigeration cycle circuit, after one refrigeration cycle circuit starts and ends the defrosting operation, the difference between the indoor air temperature sucked into the indoor unit side heat exchanger and the set value of the indoor air temperature is set. An air conditioner provided with control means for prohibiting the defrosting operation of another refrigeration cycle circuit until the temperature becomes equal to or less than a predetermined value. 3. A compressor, a four-way switching valve, an outdoor heat exchanger,
A plurality of independent refrigeration cycle circuits each having an expansion device, an indoor-side heat exchanger, and an accumulator sequentially connected by refrigerant pipes, and an indoor-side heat exchanger of each refrigeration cycle circuit arranged side by side; A single blower that blows air in common through the heat exchanger; and in each refrigeration cycle circuit, the indoor heat exchanger liquefies the high-temperature gas refrigerant and the outdoor heat exchanger evaporates the liquid refrigerant. Defrosting occurs in the outer heat exchanger, and after reaching the defrosting condition, a defrosting operation of liquefying the high-temperature gas refrigerant in the outdoor heat exchanger and evaporating the liquid refrigerant in the indoor heat exchanger is performed, and In the refrigeration cycle circuit alone, if the defrost cycle from the start of the defrost operation to the start of the next defrost operation is less than the predetermined time, the defrost operation is prohibited, and the simultaneous defrost operation of multiple refrigeration cycle circuits is prohibited. Air conditioning to control When one refrigeration cycle circuit reaches the defrosting condition while one refrigeration cycle circuit performs heating operation and the other refrigeration cycle circuit is stopped, one refrigeration cycle circuit In addition to prohibiting the defrosting operation, the heating operation of one of the other refrigeration cycle circuits is performed. At the time when the predetermined time has elapsed, it is determined again whether one of the refrigeration cycle circuits has reached the defrosting condition. An air conditioner comprising a control means for starting a defrosting operation of one refrigeration cycle circuit when a frost condition is reached. 4. A compressor, a four-way switching valve, an outdoor heat exchanger,
A plurality of independent refrigeration cycle circuits each having an expansion device, an indoor-side heat exchanger, and an accumulator sequentially connected by refrigerant pipes, and an indoor-side heat exchanger of each refrigeration cycle circuit arranged side by side; A single blower that blows air in common through the heat exchanger; and in each refrigeration cycle circuit, the indoor heat exchanger liquefies the high-temperature gas refrigerant and the outdoor heat exchanger evaporates the liquid refrigerant. Defrosting occurs in the outer heat exchanger, and after reaching the defrosting condition, a defrosting operation of liquefying the high-temperature gas refrigerant in the outdoor heat exchanger and evaporating the liquid refrigerant in the indoor heat exchanger is performed, and In the refrigeration cycle circuit alone, if the defrost cycle from the start of the defrost operation to the start of the next defrost operation is less than the predetermined time, the defrost operation is prohibited, and the simultaneous defrost operation of multiple refrigeration cycle circuits is prohibited. Air conditioning to control When one refrigeration cycle circuit reaches the defrosting condition while one refrigeration cycle circuit performs heating operation and the other refrigeration cycle circuit is stopped, one refrigeration cycle circuit The defrosting operation is prohibited and the heating operation of any other refrigeration cycle circuit is performed, and the difference between the indoor air temperature sucked into the indoor unit side heat exchanger and the set value of the indoor air temperature becomes equal to or less than a predetermined value. At the time of re-determining whether one refrigeration cycle circuit has reached the defrosting condition, and if it has reached the defrosting condition, a control means for starting a defrosting operation of one refrigeration cycle circuit is provided. Air conditioner. 5. A compressor, a four-way switching valve, an outdoor heat exchanger,
A plurality of independent refrigeration cycle circuits each having an expansion device, an indoor-side heat exchanger, and an accumulator sequentially connected by refrigerant pipes, and an indoor-side heat exchanger of each refrigeration cycle circuit arranged side by side; A single blower that blows air in common through the heat exchanger; and in each refrigeration cycle circuit, the indoor heat exchanger liquefies the high-temperature gas refrigerant and the outdoor heat exchanger evaporates the liquid refrigerant. Defrosting occurs in the outer heat exchanger, and after reaching the defrosting condition, a defrosting operation of liquefying the high-temperature gas refrigerant in the outdoor heat exchanger and evaporating the liquid refrigerant in the indoor heat exchanger is performed, and In the refrigeration cycle circuit alone, if the defrost cycle from the start of the defrost operation to the start of the next defrost operation is less than the predetermined time, the defrost operation is prohibited, and the simultaneous defrost operation of multiple refrigeration cycle circuits is prohibited. Air conditioning to control When one refrigeration cycle circuit reaches the defrosting condition while one refrigeration cycle circuit performs heating operation and the other refrigeration cycle circuit is stopped, one refrigeration cycle circuit Inhibits the defrosting operation for a certain period of time, performs a heating operation by increasing the refrigerant discharge amount of the compressor of one refrigeration cycle circuit by a certain amount, and after a certain time, one refrigeration cycle circuit Air conditioning characterized by having a control means for starting a defrosting operation of one refrigeration cycle circuit and for starting a heating operation of another refrigeration cycle if the defrosting condition is reached. apparatus. 6. A compressor, a four-way switching valve, an outdoor heat exchanger,
A plurality of independent refrigeration cycle circuits each having an expansion device, an indoor-side heat exchanger, and an accumulator sequentially connected by refrigerant pipes, and an indoor-side heat exchanger of each refrigeration cycle circuit arranged side by side; A single blower that blows air in common through the heat exchanger; and in each refrigeration cycle circuit, the indoor heat exchanger liquefies the high-temperature gas refrigerant and the outdoor heat exchanger evaporates the liquid refrigerant. Defrosting occurs in the outer heat exchanger, and after reaching the defrosting condition, a defrosting operation of liquefying the high-temperature gas refrigerant in the outdoor heat exchanger and evaporating the liquid refrigerant in the indoor heat exchanger is performed, and In the refrigeration cycle circuit alone, if the defrost cycle from the start of the defrost operation to the start of the next defrost operation is less than the predetermined time, the defrost operation is prohibited, and the simultaneous defrost operation of multiple refrigeration cycle circuits is prohibited. Air conditioning to control When one refrigeration cycle circuit reaches the defrosting condition while one refrigeration cycle circuit performs heating operation and the other refrigeration cycle circuit is stopped, one refrigeration cycle circuit When the heating operation is performed by increasing the refrigerant discharge amount of the compressor by a certain amount, and the difference between the indoor air temperature sucked into the indoor unit side heat exchanger and the set value of the indoor air temperature becomes equal to or less than a predetermined value, It is determined again whether or not one of the refrigeration cycle circuits has reached the defrosting condition. If the defrosting condition has been reached, the control means for starting the defrosting operation of one refrigeration cycle circuit and for starting the heating operation of the other refrigeration cycle is performed. An air conditioner characterized by being provided. 7. The air conditioner according to claim 1, wherein the refrigeration cycle circuit that has completed the defrosting operation continues the heating operation for a certain period of time after the termination.