JPH0914735A - Multi-system air conditioner - Google Patents

Abstract

PURPOSE: To prevent adhesion of water drops to an indoor unit and generation of molds by continuously operating an indoor blower of the indoor unit which has been achieving the room cooling for the prescribed period of time after the operation of the refrigerating cycle is stopped in realizing the switching control by a cooling/heating mode switching control means. CONSTITUTION: When the stop signal is received, a delay timer is turned on, and the operation of the refrigeration cycle is stopped. Indoor blowers 13A-13C which have been operated are continuously operated until the delay timer is completed. When the delay timer is completed, the indoor blowers 13A-13C in the continuous operation are turned off, the refrigeration cycle is switched to the heating mode, refrigerant distribution control valves 10A-10C of indoor units U1-U3 subject to the heating command signal are released to re-start the refrigeration cycle operation. The temperature of a part against which the cooled air in the indoor units is blown is gradually brought close to the room temperature to suppress generation of the dew condensation and prevent adhesion of water drops and generation of molds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-system air conditioner, and more particularly, to a refrigerating cycle in which one outdoor unit is connected to a plurality of indoor units, and a cooling operation is performed via a four-way switching valve. The present invention relates to a multi-system air conditioner which is switched to a heating mode or a heating operation mode and whose indoor units are operation-controlled via respective refrigerant flow control valves.

[0002]

2. Description of the Related Art In a multi-system air conditioner having the above structure, when a refrigeration cycle operated in a cooling operation mode is switched to a heating operation mode by a command from a remote controller attached to an indoor unit, a heating mode command is conventionally used. The received indoor unit first issued a stop command to the outdoor unit, and immediately stopped the operation of the indoor blower so as not to make people in the room feel cold. FIG. 9 shows the control part of the indoor blower in this case. In FIG. 9, the operation mode of the cooling operation or the heating operation is checked (step 51). If it is the heating operation, it is not necessary to change the operation and the heating operation control is continued as it is (step 52). The case of the cooling operation is the object of this case, and it is checked whether the stop signal accompanying the operation mode switching is received (step 5
3) If it has not been received, it is not necessary to perform any special processing, and the process returns to step 51 and the check cycle is repeated. If the reception of the stop signal is confirmed in step 53,
That is, when a signal indicating that the operation of the refrigeration cycle is stopped due to the operation mode switching is received, the indoor blower is immediately turned off (operation is stopped) and a stop signal is transmitted to the outdoor unit (step 54). After the operation is stopped, the heating mode operation is started again. By the way, when switching the refrigeration cycle that was operating in the heating mode to the cooling mode, for example, in a ceiling cassette type air conditioner in which an indoor unit is installed on the ceiling, the heat of the indoor heat exchanger that has warmed up during the heating operation is operating. In order to prevent the indoor unit from remaining in the indoor unit after the stop, a delay stop control is performed to stop the indoor blower only after continuing the operation for a while, and then the cooling operation is performed.

[0003]

The refrigerating cycle is stopped while the air conditioner is operating in the cooling mode,
Furthermore, when the indoor blower is immediately shut down, water droplets are still attached to the fins and piping of the indoor heat exchanger included in the indoor unit, and cold air remains near the indoor heat exchanger, Besides the occurrence of mold on the indoor heat exchanger and the attachment of dust to the indoor blower and the outlet, the following inconveniences occur. That is, in the multi-system air conditioner, after the cooling operation is stopped, heat is accumulated in the stopped indoor unit due to the operation for oil recovery / refrigerant recovery for the stopped indoor unit when the entire refrigeration cycle is switched to the heating mode. The problem is that water droplets adhere to the inside of the stopped indoor unit.

The present invention has been made in consideration of the above circumstances, and prevents water droplets from adhering to the indoor unit and the occurrence of mold which may occur when the refrigeration cycle that was performing the cooling operation is stopped. The purpose is to provide a cleaner, safer and more comfortable multi-system air conditioner.

[0005]

In order to achieve the above object, the invention according to claim 1 is provided with a refrigeration cycle in which a plurality of indoor units are connected to one outdoor unit, and a four-way switching valve is provided. In the multi-system air conditioner in which the indoor unit is controlled to operate by the refrigerant flow control valve while the cooling operation mode is switched to the cooling operation mode or the heating operation mode, the refrigeration cycle is changed between the cooling operation mode and the heating operation mode. When the operation mode is switched to the heating operation mode by request, the operation of the refrigeration cycle is temporarily stopped, the refrigeration cycle is switched to the heating operation mode by the four-way switching valve, and then the refrigerant flow control valve of the indoor unit that has the heating operation mode request. And the cooling / heating mode switching control means for opening the engine and restarting the operation, and the switching control by the cooling / heating mode switching control means, Characterized by comprising an indoor blower delay control means for a predetermined time indoor blower after shutdown of the refrigeration cycle of the indoor unit which carried out the bunch operation continue to be operated.

According to a second aspect of the present invention, in the multi-system air conditioner according to the first aspect, each indoor unit detects an intake air temperature of the indoor heat exchanger, and an indoor air temperature sensor. An indoor heat exchanger temperature sensor for detecting the temperature of the exchanger, and an indoor blower delay control means,
When the cooling stop signal is received, the cooling operation is performed until the difference between the intake air temperature detected by the intake air temperature sensor and the indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor becomes equal to or less than the predetermined value. The indoor blower of the indoor unit that has been used is continuously operated.

According to a third aspect of the present invention, in the multi-system air conditioner according to the first aspect, each indoor unit is provided with a temperature sensor on each of a pipe inlet side and an outlet side of the indoor heat exchanger, and an indoor blower. The delay control means, when receiving the cooling stop signal, turns on the indoor blower of the indoor unit that was performing the cooling operation until the difference between the temperatures detected by the temperature sensors on the pipe inlet side and the outlet side becomes a predetermined value or less. It is characterized by continuous operation.

According to a fourth aspect of the present invention, in the multi-system air conditioner according to the first aspect, each indoor unit has a suction air temperature sensor for detecting the temperature of the suction air of the indoor heat exchanger, and the indoor heat. The blower air temperature sensor for detecting the temperature of the blown air of the exchanger, the indoor blower delay control means, when receiving the cooling stop signal, by the suction air temperature and the blow air temperature sensor detected by the suction air temperature sensor. It is characterized in that the indoor blower of the indoor unit that has been performing the cooling operation is continuously operated until the difference with the detected blown air temperature becomes a predetermined value or less.

According to a fifth aspect of the present invention, in the multi-system air conditioner according to the first aspect, the indoor blower delay control means sets the number of revolutions of the indoor blower equal to or less than the number of revolutions at the time of receiving the operation stop signal. It is characterized by

According to a sixth aspect of the present invention, in the multi-system air conditioner according to the first aspect, the indoor blower delay control means sets the rotational speed of the indoor blower to the minimum rotational speed of the operable rotational speeds. It is characterized by

[0011]

According to the first aspect of the present invention, when the refrigeration cycle is operating in the cooling operation mode and the heating operation mode is requested,
When switching the operation mode to the heating mode, temporarily stop the operation of the refrigeration cycle, switch the refrigeration cycle to the heating operation mode by the four-way switching valve, and then open the refrigerant flow control valve of the indoor unit that has the heating mode request and open it again. When the operation is started, the indoor blower of the indoor unit that had been in the cooling operation until then is continuously operated for a predetermined time after the operation is stopped, so that the indoor heat exchanger or the indoor unit cooled in the cooling operation can be operated. The parts that were exposed to the cold air, the indoor blower, etc. are gradually brought closer to room temperature, thereby suppressing the generation of dew condensation and preventing the adhesion of water droplets and mold to the indoor unit. It is possible to dry the condensed water and provide a cleaner, safer and more comfortable multi-system air conditioner.

According to the second aspect of the present invention, the delay stop timing of the indoor blower is set until the difference between the suction temperature and the indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor becomes a predetermined value or less. To do. By doing so, it is possible to directly detect that the temperature of each component of the indoor unit approaches room temperature by using the difference between the suction temperature and the indoor heat exchanger temperature, and to achieve the same effect as the invention of claim 1. You can

According to the third aspect of the present invention, the delay stop timing of the indoor blower is set until the difference between the inlet side temperature and the outlet side temperature of the indoor heat exchanger pipe becomes a predetermined value or less. By doing so, the same effect as that of the invention of claim 1 or 2 can be obtained.

According to the fourth aspect of the present invention, the timing of the delay stop of the indoor blower is set until the difference between the intake air temperature and the blown air temperature becomes a predetermined value or less. By doing so, the same effects as those of the inventions of claims 2 to 3 can be obtained.

According to the invention of claim 5, the number of revolutions of the indoor blower up to the delay stop is set to be equal to or less than the number of revolutions at the time of receiving the operation stop signal. By doing so, the intended purpose can be achieved quickly without giving the occupants a very unpleasant feeling.

According to the sixth aspect of the invention, the number of revolutions until the indoor blower is delayed and stopped is set to the minimum number of revolutions that can be operated. By doing so, although it takes a relatively long time until the delay stop, it is possible to achieve the intended purpose while minimizing discomfort to the occupants.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows one configuration example of a heat pump type refrigeration cycle to which the present invention is applied, and FIG. 3 is a block diagram showing a device configuration of a control system for an air conditioner according to the present invention.

As shown in FIG. 2, the outdoor unit SG includes a variable capacity compressor 2 which is operated at a variable speed by an inverter (not shown). The suction side of the compressor 2 is connected to the first input end of the four-way switching valve 4 via the accumulator 3.
The discharge side of the compressor 2 is connected to the second input end of the four-way switching valve 4. The four-way switching valve 4 switches the refrigerant circulation direction of an indoor heat exchanger and an outdoor heat exchanger, which will be described later, by deactivating or energizing the operation solenoid according to the cooling operation mode or the heating operation mode. The first output end of the four-way switching valve 4 is guided to the indoor unit group via the outdoor heat exchanger 6, the expansion valve 7 for heating operation, the check valve 8 that bypasses the expansion valve 7 during cooling operation, and the liquid tank 9.

The indoor unit group comprises three sets of indoor units U1, U2, U3 in this embodiment. The first indoor unit U1 includes a refrigerant flow control valve 10A, a capillary 11A, and an indoor heat exchanger 12A that are connected in series with each other. Similarly, the second and third indoor units U2,
U3 is a refrigerant flow control valve 10B, 1 connected in series with each other
0C, capillaries 11B and 11C, and indoor heat exchanger 1
It consists of 2B and 12C. Indoor heat exchangers 12A-1
The other end of 2C is commonly connected to the second output end of the four-way switching valve 4. The connection state shown corresponds to the cooling operation mode, the outdoor heat exchanger 6 functions as a condenser (radiator), and the indoor heat exchangers 12A to 12C each function as an evaporator (cooler). By switching to a heating operation mode by exciting a solenoid (not shown) of the four-way switching valve 4, the refrigerant from the compressor 2 first passes through the indoor heat exchangers 12A to 12C and then the outdoor through the expansion valve 7. It circulates in the direction reaching the heat exchanger 6. In this case, the indoor heat exchangers 12A to 12C each function as a condenser (radiator), and the outdoor heat exchanger 6 functions as an evaporator (heat collector).

The outdoor heat exchanger 6 is provided with an outdoor blower 6F for promoting heat exchange with the atmosphere. Similarly, the indoor heat exchangers 12A to 12C are provided with cooling air or heating air in the room. Indoor blowers 13A, 13B, and 13C are provided to blow air toward each. Each indoor blower is included in the indoor unit of the corresponding indoor heat exchanger.

In the system of FIG. 2, the indoor unit U
1 to U3, that is, the compressor 2, the accumulator 3, the four-way switching valve 4, the outdoor heat exchanger 6, the expansion valve 7, the check valve 8, the liquid tank 9 and the outdoor blower 6F constitute the outdoor unit SG. . The outdoor unit SG is installed outdoors.

The indoor units U1 to U3 are provided with two or more of the following five temperature sensors as required. Here, the five types of temperature sensors are the first
Are temperature sensors 20A, 20B, 20C for detecting the temperature of the intake air from the room to the unit, that is, room temperature or intake temperatures TA1, TA2, TA3, and secondly, the temperatures TCS1, TCS2 of the indoor heat exchangers 12A, 12B, 12C. , T
Temperature sensors 21A, 21B, 21C for detecting CS3,
Thirdly, the liquid side temperature (expansion valve 7 side temperature or inlet temperature) of the pipes of the indoor heat exchangers 12A to 12C TC1A, TC1.
Temperature sensors 22A, 22B, 2 for detecting B and TC1C
2C, and fourthly, the gas side temperature of the indoor heat exchanger pipe (four-way switching valve 4 side temperature or outlet temperature) TC2A, TC2B, T
Temperature sensors 23A, 23B, 23C for detecting C2C,
Fifthly, there are temperature sensors 24A, 24B, 24C for detecting the temperature of the air blown from the unit into the room, that is, the blowout temperatures TF1, TF2, TF3. The temperature signals obtained by these temperature sensors are taken in by the indoor controllers 30A, 30B, 30C shown in FIG. 3, respectively. The indoor units U1, U2, U3 are generally arranged in different rooms, and the on / off operation is controlled by opening / closing a refrigerant flow control valve in series with the indoor heat exchanger.

FIG. 3 shows an example of the configuration of a control system for controlling the refrigeration cycle shown in FIG. Each indoor unit U1, U2, U3 is provided with an indoor controller 30A, 30B, 30C including a microprocessor. The indoor controllers 30A to 30C are provided with remote controllers (hereinafter referred to as "remote controllers") 31A, 31B, and 31C for giving an ON / OFF command for unit operation and setting a set temperature. Suction temperature TA1 detected by each temperature sensor shown in FIG.
TA2, TA3, indoor heat exchanger temperature TCS1, TCS
2, TCS3, liquid side temperature (inlet temperature) TC1A, TC1B, TC1C of indoor heat exchanger pipe, gas side temperature (outlet temperature) TC2A, TC2B, TC2 of indoor heat exchanger pipe
C and the blowout temperatures TF1, TF2, TF3 are introduced into the corresponding indoor controllers 30A to 30C. The indoor controller keeps the suction temperature (room temperature) TA1, TA2, T during the cooling operation or the heating operation at all times.
A3 performs operation control so as to approach each set temperature, controls on / off and rotation speed of the indoor blowers 13A to 13C in each unit, and controls the refrigerant flow control valve 1.
Controls ON / OFF (opening / closing) of 0A to 10C. Although not shown, the indoor controller 30A-
Each of the 30Cs has a timer function.

The outdoor unit SG is provided with an outdoor controller 32 including a microprocessor. The outdoor controller 32 is each indoor controller 30A, 30B, 30C.
Is connected to each indoor controller 30A, 30
After receiving command signals from B and 30C and performing necessary arithmetic processing, capacity adjustment including ON / OFF control of the compressor 2, that is, rotation speed (speed) adjustment, and ON / OFF of the outdoor blower 6F are performed. It also controls ON / OFF (switching between cooling operation / heating operation) of the four-way switching valve 4 (simply shown as switching valve 4 in the figure).

Before starting the description of the delay stop control of the indoor blower according to the present invention, the basic operation of the apparatus shown in FIGS. 2 and 3 will be described. In the apparatus of FIG. 2, on / off commands for operating the indoor unit and the outdoor unit are issued through remote controllers 31A to 31C attached to each indoor unit. When the operation command is issued from the remote controller, the indoor controllers 30A and 30A for each indoor unit are issued.
In B and 30C, the suction temperatures TA1 to TA3 and the set room temperatures TB1 to TB3 (standard values preset inside or values corrected by the remote controller) are compared, and their deviations, that is, temperature deviations ΔT (= room temperature TA-set room temperature). The step signal selected according to TB) is transmitted to the outdoor controller 3
2 and the refrigerant flow rate control valves 10A to 1
The opening / closing of 0C is controlled, and the indoor blowers (13A to 13C) of the indoor unit whose operation is turned on are drive-controlled.

The step signal F (X) is preset corresponding to the temperature deviation ΔT during the cooling operation and the heating operation, and according to the sign and absolute value of the temperature deviation ΔT,
For example, the compressor 2 is classified and associated with a step signal consisting of 16 steps, and the compressor 2 is operated at an operating frequency (rotation speed) according to the step signal. When the temperature deviation ΔT is less than or equal to a predetermined value during cooling operation or more than a predetermined value during heating operation, so-called “thermo off” occurs and the cooling operation or heating operation is turned off, and the temperature deviation ΔT is greater than or equal to a predetermined value during heating operation or heating operation. At times, when the temperature falls below a predetermined value, a so-called "thermo-on" occurs and the cooling operation or the heating operation is performed. In that case, the outdoor controller 32
Refers to the step signal transmitted from the indoor controllers 30A to 30C, converts it into a required frequency basic value, and further transmits the indoor units U1, U2, U3 of the transmission source.
The product obtained by multiplying the weight according to the capacity of is added up for each indoor unit, and it is taken as the required compression functional force. In this embodiment, since it is premised that three indoor units are provided, the sum of the three values will be obtained. If the indoor units have the same capacity, each weight H
(X) becomes an equal value, and regarding the indoor unit which is not operated, the required frequency basic value is unconditionally treated as zero. The outdoor controller 32 controls the rotation speed of the compressor 2 in accordance with the required compression function force thus obtained.

Now, according to the present invention, when the operation mode is switched from the cooling operation mode to the heating operation mode, water droplets adhered to the indoor unit and fungi which are generated when the refrigeration cycle which was in the cooling operation is stopped. The problem is to prevent the occurrence of. In order to solve this problem, the following operation is performed according to the present invention.
This will be described with reference to the flowcharts shown in FIG. 1 and FIG.

FIG. 1 shows a basic embodiment of the present invention. In FIG. 1, first, it is checked whether it is a cooling operation or a heating operation (step 61), and if it is a heating operation, it is not necessary to change the operation and the heating operation control is continued (step 62). If it is the cooling operation, the reception of the stop signal accompanying the change of the operation mode is checked (step 63). Here, unless a stop signal is received, the process returns to step 61 and the check cycle is repeated. When the stop signal is received, the indoor blower delay stop timer (also called a delay timer) is turned on according to the present invention to stop the operation of the refrigeration cycle (step 64). In that case,
The indoor blower that has been operated until then continues to operate and waits for the end of the delay timer (step 65). Setting time of the delay timer is determined as prospect the time required for the condensation to disappear, for example, about 2 to 3 minutes. When the delay timer expires, the indoor blower that is still in operation is turned off (step 66), the refrigeration cycle is switched to the heating operation mode, and the refrigerant circulation control valve of the indoor unit that has received the heating operation command signal is opened to perform refrigeration. The operation of the cycle is restarted (step 67).

As described above, in step 65, by continuing to operate the indoor blower for the delay time set by the delay timer, the portion of the indoor heat exchanger cooled during the cooling operation or the cold air in the indoor unit hit It is possible to gradually bring the indoor blower or the like closer to room temperature, thereby suppressing the generation of dew condensation, and preventing water droplets from adhering to the indoor unit or generation of mold.

FIG. 4 shows a modified embodiment of the present invention. In this embodiment, instead of the delay timer (step 65) in the embodiment of FIG. 1, the difference ΔTac = TA-TCS between the suction temperature TA and the indoor heat exchanger temperature TCS relating to the indoor unit that has sent the stop signal is set. To use. In FIG. 4, steps 71 to 73 are step 6 of the embodiment of FIG.
No change from 1 to 63. Here, when the stop signal is received in step 73, instead of turning on the delay timer, the difference ΔTac = T between the suction temperature TA and the indoor heat exchanger temperature TCS of the indoor unit that has sent the stop signal.
A-TCS is calculated and the operation of the refrigeration cycle is temporarily stopped (step 74). Again, the indoor blower that had been operating until then continues to operate, and the temperature difference Δ
Wait for Tac to fall below a predetermined value Tα (step 7).
5). Predetermined value Tα be determined as prospect time condensation disappears, for example, 1 ° C.. The temperature difference ΔTac is the predetermined value T
When it decreases to less than α, the indoor blower under continuous operation is turned off (step 76), the refrigeration cycle is switched to the heating operation mode, and the refrigerant circulation control valve of the indoor unit that was in the heating operation is opened to operate the refrigeration cycle. Is restarted (step 77).

Here, the fact that the temperature of each component of the indoor unit approaches room temperature is detected more directly using the difference ΔTac between the suction temperature TA and the indoor heat exchanger temperature TCS, and The same effect as the invention can be obtained.

FIG. 5 shows another modified embodiment. In this embodiment, instead of the difference ΔTac between the suction temperature TA and the indoor heat exchanger temperature TCS in the embodiment of FIG. 4, the liquid side (inlet) of the pipe of the indoor heat exchanger related to the indoor unit that has sent the stop signal. ) Temperature (expansion valve 7 side temperature) TC
1 and the gas side (outlet) temperature of the indoor heat exchanger pipe (temperature on the four-way switching valve 4 side) TC2, ΔTC = TC2-TC1 is used. In FIG. 5, steps 81-83 are the same as steps 61-63 of the embodiment of FIG. here,
When the stop signal is received in step 83, the difference ΔTC = TC2-TC1 between the liquid side temperature TC1 of the pipe of the indoor heat exchanger and the gas side temperature TC2 of the indoor heat exchanger pipe of the indoor unit that has transmitted the stop signal. And the operation of the refrigeration cycle is temporarily stopped (step 8
4). Here again, the indoor blower that has been operated until then continues to operate, and waits for the temperature difference ΔTC to decrease below the predetermined value Tβ (step 85). The predetermined value Tβ is also determined in the same way as the predetermined value Tα, and may be 1 ° C., for example. When the temperature difference ΔTC is reduced to a predetermined value Tβ or less, the indoor blower under continuous operation is turned off (step 86), the refrigeration cycle is switched to the heating operation mode, and the refrigerant flow control valve of the indoor unit that is in the heating operation is opened. age,
The operation of the refrigeration cycle is restarted (step 87).

In this embodiment, the fact that the temperature of each component of the indoor unit approaches room temperature can be determined more directly by using the difference ΔTC between the liquid side temperature TC1 and the gas side temperature TC2 of the indoor heat exchanger pipe. It is possible to obtain the same effect as the invention of claim 1 (FIG. 1) or claim 2 (FIG. 4) by detecting.

FIG. 6 shows still another modified embodiment. In this embodiment, the liquid side temperature TC1 and the gas side temperature T of the indoor heat exchanger pipe in the embodiment of FIG.
Instead of the difference ΔTC of C2, the difference Δ of the intake temperature TA and the outlet temperature TF of the indoor unit that has sent the stop signal.
Use Taf = TA-TF. In FIG. 6, step 9
1 to 93 are the same as steps 61 to 63 in the embodiment of FIG. In this embodiment, when the stop signal is received in step 93, the difference ΔTaf = T between the intake temperature TA and the outlet temperature TF of the indoor unit that has sent the stop signal.
A-TF is calculated and the operation of the refrigeration cycle is temporarily stopped (step 94). Again, the indoor blower that had been operating until then continues to operate, and the temperature difference Δ
Wait for Taf to decrease below a predetermined value Tγ (step 9)
5). The predetermined value Tγ may also be about 1 ° C. Temperature difference ΔTaf
Is reduced to a predetermined value Tγ or less, the indoor blower under continuous operation is turned off (step 96), the refrigeration cycle is switched to the heating operation mode, and the refrigerant flow control valve of the indoor unit that was in the heating operation is opened to perform refrigeration. The operation of the cycle is restarted (step 97).

In this embodiment, the fact that the temperature of each component of the indoor unit approaches room temperature means that the difference ΔTC between the liquid side temperature TC1 and the gas side temperature TC2 of the indoor heat exchanger pipes.
It is possible to obtain the same effect as that of the invention of claim 1 (FIG. 1), claim 2 (FIG. 4), or claim 3 (FIG. 5).

FIG. 7 shows a modification of the above-mentioned embodiments. The feature of this embodiment lies in step 104.
It is in. 7, steps 101 to 103 are shown in FIG.
This is the same as steps 61 to 63 in the above embodiment. In this embodiment, when the stop signal is received in step 103, the indoor blower delay stop timer is turned on to stop the operation of the refrigeration cycle and at the same time, the indoor blower speeds down to continue the operation (step 104). In that state, the end of the delay timer is waited for (step 105), when the delay timer ends, the indoor blower that is still in operation is turned off (step 106), the refrigeration cycle is switched to the heating operation mode, and the heating operation is performed in the room. The refrigerant flow control valve of the unit is opened, and the operation of the refrigeration cycle is restarted (step 107).

According to this embodiment, the intended purpose (to bring the temperature of each constituent device of the indoor unit close to room temperature) quickly without giving an uncomfortable feeling to the occupants in the room.
Can be achieved.

FIG. 8 shows still another modification of the embodiment shown in FIG. The feature of this embodiment lies in step 114. In FIG. 8, steps 111 to 11
Step 3 is the same as steps 61 to 63 in the embodiment of FIG. In this embodiment, when the stop signal is received in step 113, the indoor blower delay stop timer is turned on to stop the operation of the refrigeration cycle and continue the operation of the indoor blower at the minimum possible rotation speed (step). 114). In that state, the end of the delay timer is waited for (step 115), and when the delay timer ends, the indoor blower that is still in operation is turned off (step 116), the refrigeration cycle is switched to the heating operation mode, and the room where the heating operation is performed is performed. The refrigerant flow control valve of the unit is opened and the operation of the refrigeration cycle is restarted (step 117).

According to this embodiment, although it takes a relatively long time until the delay stop, it is possible to achieve the intended purpose while suppressing the discomfort to the occupants in the room to the minimum.

[0040]

As described above, according to the present invention, when the cooling operation is stopped, the indoor heat exchanger cooled during the cooling operation, the portion of the indoor unit that is exposed to the cool air, the indoor blower, etc. are gradually removed. It is possible to provide a cleaner, safer and more comfortable multi-system air conditioner that is close to room temperature, thereby suppressing the generation of dew condensation, preventing water droplets from adhering to indoor units, and preventing mold.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a system diagram of a refrigeration cycle for carrying out the present invention and a diagram for explaining an arrangement position of each temperature sensor.

3 is a block diagram showing a control system of an air conditioner including the refrigeration cycle shown in FIG.

FIG. 4 is a flowchart showing another embodiment of the present invention.

FIG. 5 is a flowchart showing still another embodiment of the present invention.

FIG. 6 is a flowchart showing still another embodiment of the present invention.

FIG. 7 is a flowchart showing still another embodiment of the present invention.

FIG. 8 is a flowchart showing still another embodiment of the present invention.

FIG. 9 is a flowchart showing a control mode according to a conventional technique.

[Explanation of symbols]

SG Outdoor unit 2 Compressor 4 Four-way switching valve 6 Outdoor heat exchanger U1, U2, U3 Indoor unit 10A, 10B, 10C Refrigerant flow control valve 12A, 12B, 12C Indoor heat exchanger 13A, 13B, 13C Indoor blower 20A, 20B , 20C Suction air temperature sensor 21A, 21B, 21C Indoor heat exchanger temperature sensor 22A, 22B, 22C Indoor heat exchanger pipe liquid side temperature sensor 23A, 23B, 23C Indoor heat exchanger pipe gas side temperature sensor 24A, 24B, 24C Blown air temperature sensor 30A, 30B, 30C Indoor controller 31A, 31B, 31C Remote controller 32 Outdoor controller

Claims (6)

[Claims] 1. A refrigeration cycle in which a plurality of indoor units are connected to one outdoor unit, is switched to a cooling operation mode or a heating operation mode via a four-way switching valve, and the indoor units are each provided with a refrigerant flow. In a multi-system air conditioner operation-controlled via a control valve, during operation of the refrigeration cycle in a cooling operation mode, when the operation mode is switched to the heating operation mode due to a request of a heating operation mode, operation of the refrigeration cycle To stop,
After switching the refrigerating cycle to the heating operation mode by the four-way switching valve, the cooling / heating mode switching control means for opening the refrigerant flow control valve of the indoor unit having the heating operation mode request and restarting the operation, and the cooling / heating mode switching When switching control by the control means is performed, an indoor blower delay control means for operating the indoor blower of the indoor unit that was performing the cooling operation continuously for a predetermined time after the refrigeration cycle is stopped, A multi-system air conditioner. 2. The multi-system air conditioner according to claim 1, wherein each indoor unit detects the temperature of the intake air of the indoor heat exchanger and the temperature of the indoor heat exchanger. And an indoor heat exchanger temperature sensor, wherein the indoor blower delay control means, when receiving a cooling stop signal, is detected by the intake air temperature detected by the intake air temperature sensor and the indoor heat exchanger temperature sensor. A multi-system air conditioner characterized by continuously operating an indoor blower of an indoor unit that has been performing a cooling operation until the difference between the temperature of the indoor heat exchanger and a predetermined value or less. 3. The multi-system air conditioner according to claim 1, wherein each indoor unit is provided with a temperature sensor at each of a pipe inlet side and an outlet side of the indoor heat exchanger, and the indoor blower delay control means is a cooling unit. When the stop signal is received, the indoor blower of the indoor unit that was performing the cooling operation is continuously operated until the difference in temperature detected by both the temperature sensors on the inlet side and the outlet side of the pipe becomes less than or equal to a predetermined value. A multi-system air conditioner characterized by that. 4. The multi-system air conditioner according to claim 1, wherein each indoor unit has a suction air temperature sensor for detecting a temperature of intake air of the indoor heat exchanger, and a temperature of blown air of the indoor heat exchanger. And a blowout temperature detected by the blowout air temperature sensor, the indoor blower delay control means, when receiving a cooling stop signal, the blowout temperature detected by the suction air temperature sensor. A multi-system air conditioner characterized by continuously operating an indoor blower of an indoor unit that has been performing a cooling operation until a difference from an air temperature becomes a predetermined value or less. 5. The multi-system air conditioner according to claim 1, wherein the indoor blower delay control means sets the rotational speed of the indoor blower to be equal to or lower than the rotational speed at the time of receiving the operation stop signal. A multi-system air conditioner. 6. The multi-system air conditioner according to claim 1, wherein the indoor blower delay control means sets the rotation speed of the indoor blower to the lowest rotation speed of the operable rotation speeds. A multi-system air conditioner.