JPH1038358A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner in which an over-loaded condition of an outdoor device is eliminated while a dew formation or the like in an indoor device is being prevented. SOLUTION: When an outdoor device ECU 61 discriminates that an outdoor device 3 is in an over-loaded condition in response to a result of sensing of a pressure sensor 63 or a fuel flow rate sensor 65, it decreases the number of rotation of an electric fan 9 by a predetermined amount in preference to one of a plurality of indoor devices 1 showing a low indoor air temperature in reference to a result of sensing of an indoor temperature sensor 53 until its over-loaded condition is eliminated, thereafter it reduces an opening amount of an electric expansion valve 11 by a predetermined amount in a repetitive manner. Then, in the case that the indoor device has a surplus amount of load, an opening amount of the electric expansion valve 11 of one of a plurality of indoor devices 1 showing a high temperature of indoor air is preferentially increased by a predetermined amount, thereafter the number of rotation of the electric fan 9 is increased by a predetermined amount in a repetitive manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly, to a technique for eliminating an overload state of an outdoor unit while preventing dew condensation or the like in an indoor unit.

[0002]

2. Description of the Related Art In general, in an air conditioner, the capacity of an indoor unit and the capacity of an outdoor unit are set to be equal so that the load on the outdoor unit does not become excessive when the load on the indoor unit is maximized. ing.

However, not only when the outside air temperature is abnormally high, but also depending on the installation condition of the outdoor unit, etc.
An overload condition occurs in the outdoor unit. For example, when a shield is arranged around the outdoor unit, an air shortage phenomenon occurs in which warm air from the outlet circulates to the inlet,
The heat exchange efficiency in the outdoor heat exchanger is significantly reduced. As a result, the outdoor unit falls into an overload state due to a substantial decrease in capacity, the refrigerant pressure on the high pressure side abnormally increases, and the fusible plug melts, or a drive source for the compressor (such as an electric motor or an internal combustion engine). However, there was a problem that the entire apparatus stopped.

When a large number of indoor units are connected to a single outdoor unit, the sum of the abilities of all the indoor units may be larger than that of the outdoor units. This does not presuppose the simultaneous operation of the indoor units. However, if all the indoor units are simultaneously operated for some reason, the outdoor units fall into an overloaded state, and the above-described problem also occurs.

In order to solve such a problem, Japanese Patent Laid-Open No.
In the air conditioner described in -177758 and the like,
An overload elimination method of reducing the flow rate of the refrigerant at the time of overload is adopted. In this method, the outside air temperature and the temperature of the refrigerant condensing section are detected, and when these values exceed respective predetermined determination values, it is determined that an overload condition has occurred. Decrease the rotational speed of the drive source. Thus, the amount of refrigerant flowing into the indoor heat exchanger and the amount of refrigerant flowing into the outdoor heat exchanger are both reduced, and the overload state of the outdoor unit is eliminated.

[0006]

However, in the above-described overload elimination method, there is a possibility that the following problems may occur by reducing the opening of the expansion valve.

Generally, when the expansion valve is in a steady operation opening degree,
The liquid refrigerant condensed in the outdoor heat exchanger flows into the indoor heat exchanger and then gradually evaporates from the inlet side to the outlet side by absorbing the heat energy of the indoor air blown by the blower, and The gas reaches the outlet of the heat exchanger and becomes a saturated gas (gas refrigerant). Therefore, indoor air is cooled substantially uniformly over the entire surface when passing through the indoor heat exchanger,
Dehumidification is also performed uniformly.

However, when the opening of the expansion valve is reduced from the steady operation opening, a relatively small amount of the liquid refrigerant is completely vaporized in the middle part of the indoor heat exchanger, and the temperature from that part to the outlet is high. And flows through the indoor heat exchanger. As a result, the indoor air passing through the inlet side of the indoor heat exchanger is cooled and dehumidified into low-temperature dry air, but the indoor air passing through the outlet side is not cooled and dehumidified, and the indoor heat exchange is performed as hot, humid air. Spills from container. As a result, when low-temperature dry air and high-temperature humid air merge in a duct or the like after passing through the indoor heat exchanger, the moisture contained in the high-temperature humid air is cooled and condensed, and the louvers and flaps at the outlet Condensation occurs on the surface The water generated by the dew condensation may cause the carpets and the like in the room to be stained by dripping, and may generate molds and the like on louvers and flaps.

The present invention has been made in view of the above situation,
It is an object of the present invention to provide an air conditioner that eliminates an overload state of an outdoor unit while preventing dew condensation or the like in an indoor unit.

[0010]

According to a first aspect of the present invention, there is provided an outdoor unit having a compressor and an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, and a blower. An air conditioner including an indoor unit,
Load detection means for detecting the load of the outdoor unit during cooling operation, expansion valve driving means for driving the expansion valve to increase or decrease the flow rate of refrigerant flowing through the indoor heat exchanger, and the indoor heat exchanger Blower driving means for driving the blower so as to increase or decrease the blown amount of indoor air passing therethrough, and the expansion valve driving means when it is determined from the detection result of the load detection means that the outdoor unit is in an overloaded state. And controlling the blower driving means to provide an overload eliminating means for alternately performing a process of decreasing the refrigerant flow rate and a process of decreasing the blowing amount until the overload state is eliminated. I do.

According to this invention, even if the outdoor unit is overloaded and the liquid refrigerant flowing through the indoor heat exchanger is reduced by the expansion valve driving means, it passes through the indoor heat exchanger by the blower driving means. Since the amount of air to be blown is reduced, the heat energy of the indoor air absorbed by the liquid refrigerant also decreases. As a result, the refrigerant does not enter a heated gas state in the middle of the indoor heat exchanger, and the indoor air is substantially uniformly cooled over the entire surface when passing through the indoor heat exchanger, so that dehumidification is also performed uniformly.

[0012] According to the second aspect of the present invention, there is provided an air conditioner including an outdoor unit having a compressor and an outdoor heat exchanger, and an indoor unit having an expansion valve, an indoor heat exchanger, and a blower, Load detection means for detecting the load of the outdoor unit during cooling operation, expansion valve driving means for driving the expansion valve to increase or decrease the flow rate of refrigerant flowing through the indoor heat exchanger, and the indoor heat exchanger In order to increase or decrease the blowing amount of indoor air passing through, when it is determined that the outdoor unit is in an overloaded state based on the detection result of the blower driving unit that drives the blower and the load detection unit,
By controlling the expansion valve drive means and the blower drive means,
It is proposed to provide an overload eliminating means for repeatedly performing a process of decreasing the flow rate of the refrigerant by a predetermined amount after reducing the blowing amount by a predetermined amount until the overload state is eliminated.

According to the present invention, when the outdoor unit is overloaded, the amount of air passing through the indoor heat exchanger is reduced by the blower driving means, and then the air is circulated through the indoor heat exchanger by the expansion valve driving means. Liquid refrigerant is reduced. As a result, the heat energy of the indoor air absorbed by the liquid refrigerant is reduced first, and the refrigerant is completely prevented from being in a heated gas state in the middle of the indoor heat exchanger, and has passed through the indoor heat exchanger. The temperature of the indoor air is kept relatively low.

According to a third aspect of the present invention, there is provided an air conditioner including an outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of indoor units having an expansion valve, an indoor heat exchanger, and a blower. A load detecting means for detecting a load of the outdoor unit during a cooling operation, an indoor temperature detecting means for detecting an indoor temperature of a room in which the indoor unit is installed, and a flow rate of refrigerant flowing through the indoor heat exchanger. Expansion valve drive means for driving the expansion valve, blower drive means for driving the blower to increase or decrease the amount of indoor air blown through the indoor heat exchanger, and the load detection means When it is determined from the detection result that the outdoor unit is in an overloaded state, the expansion unit driving unit and the blower driving unit are controlled to maintain the indoor unit until the overloaded state is eliminated. Overload elimination that alternately performs the process of reducing the refrigerant flow rate and the process of decreasing the blown air volume, with priority given to the indoor unit having a low indoor air temperature based on the detection result of the degree detection unit. With means.

According to this invention, even when the outdoor unit is overloaded and the liquid refrigerant flowing through the indoor heat exchanger is reduced by the expansion valve driving means, the outdoor unit passes through the indoor heat exchanger by the blower driving means. Since the amount of air to be blown is reduced, the heat energy of the indoor air absorbed by the liquid refrigerant also decreases. As a result, the refrigerant does not enter a heated gas state in the middle of the indoor heat exchanger, and the indoor air is substantially uniformly cooled over the entire surface when passing through the indoor heat exchanger, so that dehumidification is also performed uniformly. In order to eliminate overload, priority is given to an indoor unit having a low indoor air temperature, so that a difference in indoor temperature between the rooms is reduced.

Further, the invention according to claim 4 is an air conditioner comprising an outdoor unit having a compressor and an outdoor heat exchanger, and a plurality of indoor units having an expansion valve, an indoor heat exchanger and a blower. A load detecting means for detecting a load of the outdoor unit during a cooling operation, an indoor temperature detecting means for detecting an indoor temperature of a room in which the indoor unit is installed, and a flow rate of refrigerant flowing through the indoor heat exchanger. Expansion valve drive means for driving the expansion valve, blower drive means for driving the blower to increase or decrease the amount of indoor air blown through the indoor heat exchanger, and the load detection means When it is determined from the detection result that the outdoor unit is in an overloaded state, the expansion unit driving unit and the blower driving unit are controlled to maintain the indoor unit until the overloaded state is eliminated. The process of decreasing the flow rate of the refrigerant by a predetermined amount after reducing the blowing amount by a predetermined amount is repeatedly performed by giving priority to the indoor unit having a lower temperature of the indoor air based on the detection result of the degree detecting means. A device having overload elimination means is proposed.

According to the present invention, when the outdoor unit is overloaded, the amount of air passing through the indoor heat exchanger is reduced by the blower driving means, and then the air flows through the indoor heat exchanger by the expansion valve driving means. Liquid refrigerant is reduced. As a result, the heat energy of the indoor air absorbed by the liquid refrigerant is reduced first, and the refrigerant is completely prevented from being in a heated gas state in the middle of the indoor heat exchanger, and has passed through the indoor heat exchanger. The temperature of the indoor air is kept relatively low. In order to eliminate overload, priority is given to an indoor unit having a low indoor air temperature, so that a difference in indoor temperature between the rooms is reduced.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a gas heat pump type air conditioner, in which a refrigerant circuit is indicated by a solid line,
The electric circuit is indicated by a dashed line. The air conditioner according to the present embodiment is a so-called multi-type package air conditioner, and includes a plurality of indoor units 1 and one outdoor unit 3. On the indoor unit 1 side, an indoor heat exchanger 7 provided with a flow divider 5, an electric fan 9, an electric expansion valve 11 and the like are installed. On the outdoor unit 3 side, a compressor 13, an electromagnetic four-way valve 15, an outdoor heat exchanger 19 provided with a flow divider 17, an electric fan 21, an accumulator 23, and the like are installed. The equipment constituting the refrigerant circuit is connected by refrigerant pipes 31 to 45 provided for the flow of the gas refrigerant or the liquid refrigerant. In the figure, reference numeral 25 denotes a gas engine, which drives the compressor 13 via a flexible coupling 27.

In the indoor unit 1, an indoor control unit (hereinafter referred to as ECU) 51 for driving the electric fan 9 and the electric expansion valve 11 is provided. The indoor ECU 51 includes a CPU, an input / output interface, a ROM, a RAM, a timer counter, and the like. The input interface includes a room temperature sensor 53 for detecting a room temperature Tr, and an inlet side of the indoor heat exchanger 7. And first and second refrigerant temperature sensors 55 and 57 for detecting refrigerant temperatures Tfi and Tfo on the outlet side are connected.

On the other hand, inside the outdoor unit 3, an outdoor ECU 61 for driving and controlling the four-way valve 15, the electric fan 21, the gas engine 25 and the like is provided. Outdoor ECU
61 is a CPU, an input / output interface and an RO
The input interface includes a pressure sensor 63 for detecting the refrigerant pressure Pd on the discharge side of the compressor 13, and a fuel flow sensor 65 for detecting the fuel consumption Qf of the gas engine 25. , An outside air temperature sensor 67 for detecting the outside air temperature Ta, and the like. Further, the outdoor ECU 61 is configured to control the indoor side E of each indoor unit 1.
It is connected to the CU 51 and exchanges signals with each other.

Next, the flow of the refrigerant during the cooling operation will be described.

The gas refrigerant sucked into the compressor 13 from the refrigerant pipe 39 becomes high temperature and high pressure by adiabatic compression, and
3 and flows into the outdoor heat exchanger 19 via the refrigerant pipe 31, the four-way valve 15, and the refrigerant pipe 32. The high-temperature and high-pressure gas refrigerant is cooled by the outside air while passing through the outdoor heat exchanger 19, condensed into a liquid refrigerant, and then flows into the electric expansion valve 11 via the refrigerant pipes 33 and 34. .

After the flow rate of the liquid refrigerant is adjusted by the electric expansion valve 11, the liquid refrigerant flows into the indoor heat exchanger 7 via the refrigerant pipe 35 and the flow divider 5. The liquid refrigerant is vaporized while passing through the indoor heat exchanger 7 to become a gas refrigerant, and cools the indoor air blown by the electric fan 9 by the latent heat of vaporization at that time. At this time, the indoor ECU 51 controls the rotation speed (rpm) of the electric fan 9 based on the difference between the set temperature Ts and the room temperature Tr, and also controls the inlet-side refrigerant temperature Tfi and the outlet-side refrigerant temperature Tfo of the indoor heat exchanger 7. The opening amount of the electric expansion valve 11 (the number of steps of the step motor for driving the valve body) is controlled so that the deviation from the predetermined value (for example, 0 to 1 ° C.).

The gas refrigerant vaporized in the indoor heat exchanger 7 is:
The refrigerant flows into the accumulator 23 via the refrigerant pipes 36 and 37, the four-way valve 15, and the refrigerant pipe 38, and is sucked into the compressor 13 again from the refrigerant pipe 39.

Hereinafter, the load elimination control according to the present embodiment will be described with reference to the flowcharts of FIGS.

When the air conditioner is started, the outdoor ECU
61 is based on a predetermined control interval,
The load elimination control is repeatedly executed according to the procedure shown in FIG. When the load canceling control is started, the outdoor ECU 61 firstly performs the operation shown in FIG.
In step S1, the detection information (the discharge side refrigerant pressure Pd, the fuel consumption Qf,
After reading the outside air temperature Ta, etc., the communication information from each indoor ECU 51 is read in step S3.

Next, the outdoor ECU 61 proceeds to step S5.
It is determined whether or not the compressor 13 (that is, the engine 25) is operating, and if this determination is Yes (Yes), it is determined in step S7 whether or not the outdoor unit 3 has a load margin. judge. In the case of the present embodiment, the load margin and overload of the outdoor unit 3 are obtained from the discharge-side refrigerant pressure Pd of the compressor 13 and the fuel consumption Qf of the engine 25. For example, the discharge side refrigerant pressure Pd and the maximum allowable pressure Pmax
A deviation ΔP from (in the present embodiment, 2.3 MPa) is obtained. If the deviation ΔP is larger than a predetermined value, there is a load margin, and if the deviation becomes a negative value, an overload state occurs. Further, a deviation ΔQf between the fuel consumption Qf and the allowable maximum fuel consumption Qfmax is obtained, and if this is larger than a predetermined value, there is a load margin, and if this becomes a negative value, an overload state occurs.

If the outdoor unit 3 has no load margin and the determination in step S7 is No (No), the outdoor EC
U61 determines in step S9 whether or not the outdoor unit 3 is in an overload state. Then, when this determination becomes Yes due to an increase in the discharge-side refrigerant pressure Pd or the fuel consumption Qf, the outdoor ECU 61 determines whether or not the first switching flag FCHG1 is 1 in step S11. The first switching flag FCHG1 is a flag that indicates a switching state between the blowing amount control and the refrigerant flow control, and its initial value is set to 0.

Immediately after the outdoor unit 3 is overloaded, the determination in step S11 becomes No. Therefore, the outdoor ECU 61 determines whether the first set flag Fset1 is 1 in step S13 in FIG. Determine whether or not. The first set flag Fset1 is a flag indicating that the determination rotation speed described below has been set, and its initial value is set to 0. Since the first determination in step S13 is No, the outdoor ECU 61 sets the determination rotation speed NFtgt (rpm) of the electric fan 9 to eliminate the overload in step S15, and then sets the first set flag in step S17. Fset1 is set to 1. Note that the determination rotation speed NFtgt may be obtained by calculation based on the current average rotation speed NFave of each electric fan 9, or may be a value stored in the ROM in advance.

When the setting of the determination rotational speed NFtgt is completed, the outdoor ECU 61 determines in step S19 that the first start flag Fst
It is determined whether 1 is 1 or not. First start flag Fst1
Is a flag indicating that the air volume control has been started to eliminate the overload, and its initial value is set to 0.
Since the first determination in step S19 is No, the outdoor ECU 61 determines in step S21 that the control variable i has the initial value 0.
Is set to 1, the first start flag Fst1 is set in step S23.
Is set to 1.

Next, the outdoor ECU 61 proceeds to step S2.
In 5, it is determined whether or not the control variable i exceeds the number of installed indoor units 1 N (for example, 5). Since this determination is No for the first time (i = 1), the outdoor EC
U61 determines the room temperature Tr among the rooms in step S27.
Is searched for an indoor unit UCi (= UC1) having a low value. Thereafter, the outdoor ECU 61 determines in step S29 whether or not the indoor unit UC1 is operating.
If o, the process returns to the start without performing any processing. If Yes, it is determined in step S31 whether or not the rotation speed NF1 of the electric fan 9 of the indoor unit UC1 is larger than the determination rotation speed NFtgt.

If the determination in step S31 is No, the process returns to the start without performing any processing. If the determination is Yes, the outdoor ECU 61 determines in step S33 that the indoor ECU 51
To reduce the rotation speed NF1 of the electric fan 9 by a predetermined reduction amount NFa.

As a result, the amount of air blown to the indoor heat exchanger 7 is reduced on the indoor unit UC1 side to reduce the cooling capacity, while the load on the outdoor unit 3 is reduced. At this point, only the amount of air blow is reduced, so that the liquid refrigerant is not completely vaporized in the middle part of the indoor heat exchanger, and the temperature of the cool air from the outlet is kept relatively low.

If the overload state has not been resolved when returning to the start, the outdoor ECU 61 determines that the determinations in steps S13 and S19 are "Yes".
At 35, 1 is added to the control variable i. Then, step S2
If the determination of 5 is Yes, the outdoor ECU 61 searches for an indoor unit UC2 having the second lowest room temperature Tr in each room in step S27. Then, the outdoor ECU 61
Determines in step S29 whether or not the indoor unit UC2 is in operation. If the determination is Yes, the process proceeds to step S29.
At 31, it is determined whether or not the rotation speed NF2 of the electric fan 9 of the indoor unit UC2 is greater than the determination rotation speed NFtgt.

If the determination in step S31 is Yes, the outdoor ECU 61 determines in step S33 that the indoor E
A control command is output to the CU 51 to reduce the rotation speed NF2 of the electric fan 9 by a predetermined reduction amount NFa.

When the overload condition is not resolved, the outdoor ECU 61 controls the air flow to the other indoor units 1 in the same manner. When the control variable i exceeds the number N of installations by the end of the air volume control of all the indoor units 1 and the determination in step S25 is Yes, the outdoor EC
U61 sets the first switching flag FCHG1 to 1 at step S37.
And the first start flag Fst1 and the first set flag Fs
Let et1 be 0.

If the overload condition has not been resolved when returning to the start after the air flow control, the outdoor ECU 6
1, since the determination in step S11 is Yes this time,
In step S41 of FIG. 4, it is determined whether the second set flag Fset2 is 1. The second set flag Fset2 is a flag indicating that a determination valve opening amount described below has been set, and its initial value is set to 0. Step S41
Since the first determination of No. is No, the outdoor ECU 61
Electric expansion valve 1 for eliminating overload in step S43
After setting the determination valve opening PVtgt (the number of steps) of 1,
In step S45, the second set flag Fset2 is set to 1.
The determination valve opening PVtgt may be obtained by a calculation based on the current average valve opening PVave of each electric expansion valve 11, or may be a value stored in the ROM in advance.

When the setting of the determination valve opening PVtgt is completed, the outdoor ECU 61 determines in step S47 that the second start flag Fst
It is determined whether or not 2 is 1. Second start flag Fst2
Is a flag indicating that refrigerant flow control has been started to eliminate overload, and its initial value is set to 0. Since the first determination in step S47 is No, the outdoor ECU 61 sets the control variable i of the initial value 0 to 1 in step S49, and then sets the second start flag F in step S51.
Set st2 to 1.

Next, the outdoor ECU 61 proceeds to step S5.
At 3, it is determined whether or not the control variable i exceeds the number N of indoor units 1 installed. Then, since this determination is No for the first time (i = 1), the outdoor ECU 61 searches for an indoor unit UCi (= UC1) having the lowest room temperature Tr among the rooms in step S55. After a while, outdoor EC
U61 determines in step S57 whether or not the indoor unit UC1 is in operation. If this determination is No, the process returns to the start without performing any processing. If Yes, the indoor unit UC1 is reset in step S59. Opening amount P of the electric expansion valve 11
It is determined whether or not V1 is greater than the determination valve opening PVtgt.

If the determination in step S59 is No, the process returns to the start without performing any processing. If the determination is Yes, the outdoor ECU 61 determines in step S61 that the indoor ECU 51
To reduce the valve opening PV1 of the electric expansion valve 11 by a predetermined reduction PVa.

Thus, the flow rate of the refrigerant decreases on the side of the indoor unit UC1 and the cooling capacity decreases, while the load on the side of the outdoor unit 3 is reduced. At this point, since the amount of air has already been reduced, it is possible to prevent the liquid refrigerant from being entirely vaporized in the middle part of the indoor heat exchanger.

If the overload condition has not been resolved when returning to the start, the outdoor ECU 61 determines that the determinations in steps S41 and S47 are "Yes" this time.
At 63, 1 is added to the control variable i. Then, step S5
If the determination in Step 3 is Yes, the outdoor ECU 61 searches for an indoor unit UC2 having the second lowest room temperature Tr among the rooms in Step S55. Then, the outdoor ECU 61
Determines in step S57 whether or not the indoor unit UC2 is in operation. If the determination is Yes, the process proceeds to step S57.
At 59, it is determined whether or not the valve opening PV2 of the electric fan 9 of the indoor unit UC2 is larger than the determination valve opening PVtgt.

If the determination in step S59 is Yes, the outdoor ECU 61 determines in step S61 that the indoor E
A control command is output to the CU 51 to reduce the valve opening amount PV2 of the electric fan 9 by a predetermined reduction amount PVa.

When the overload condition is not resolved, the outdoor ECU 61 controls the flow rate of the refrigerant for the other indoor units 1 in the same manner. And all indoor units 1
When the control variable i exceeds the installed number N by the end of the refrigerant flow rate control of step S53, and the determination in step S53 becomes Yes, the outdoor side E
The CU 61 sets the first switching flag FCHG1 in step S65,
The second start flag Fst2 and the second set flag Fset2 are set to 0.

If the overload condition has not been resolved at the time when the flow returns to the start after finishing the refrigerant flow control, the determination in step S11 becomes No again, so that the outdoor ECU 6
1 shifts to step S13 in FIG. 3 to perform the blowing amount control. That is, the above-described air flow rate control and refrigerant flow rate control are alternately performed until the overload state is eliminated, and the overload state is gradually eliminated. At this time, since both the determination in step S13 in the blowing amount control and the determination in step S41 in the refrigerant flow rate control are No, the determination rotation speed NFtgt of the electric fan 9 and the determination opening amount PVtgt of the electric expansion valve 11 are the same. It is newly set each time.

When the overload state is eliminated by such a procedure and the determination in step S9 is No, the outdoor ECU 61 returns to the start without performing any processing. When the outdoor unit 3 has a load margin due to a decrease in the outside air temperature Ta or the like, and the determination in step S7 becomes Yes, the outdoor ECU 61 performs the air volume control and the refrigerant flow control in step S71 to eliminate the overload. It is determined whether or not it has been performed. If the determination is No, the process returns to the start without performing any processing. If the determination is Yes, the process proceeds to step S
At 73, it is determined whether or not the second switching flag FCHG2 is 1. The second switching flag FCHG2 is a flag indicating a switching state between the refrigerant flow rate control and the air flow rate control, and its initial value is set to 0.

Immediately after a load margin occurs in the outdoor unit 3, the determination in step S73 becomes No.
Next, the CU 61 determines whether or not the third set flag Fset3 is 1 in step S75 of FIG. The third set flag Fset3 is a flag indicating that the determination valve opening amount described below has been set, and its initial value is set to 0. Since the first determination in step S75 is No, the outdoor ECU 61 sets the determination opening amount PVtgt of the electric expansion valve 11 for returning to the steady load in step S77, and then sets the third set flag Fset3 in step S79. 1
And

When the setting of the determination valve opening PVtgt is completed, the outdoor ECU 61 determines in step S81 that the third start flag Fst
It is determined whether 3 is 1 or not. Third start flag Fst3
Is a flag indicating that the refrigerant flow control has been started to return to the normal operation, and its initial value is set to 0. Since the first determination in step S81 is No, the outdoor ECU 61 sets the control variable i to 1 in step S83, and then sets the third start flag Fst3 to 1 in step S85.

Next, the outdoor ECU 61 proceeds to step S8.
At 7, it is determined whether or not the control variable i exceeds the installed number N of the indoor units 1. Then, since this determination is No for the first time (i = 1), the outdoor ECU 61 searches for an indoor unit UHi (= UH1) having the highest room temperature Tr in each room in step S89. After a while, outdoor EC
U61 determines in step S91 whether or not the indoor unit UH1 is in operation. If this determination is No, the process returns to the start without performing any processing. If Yes, the indoor unit UH1 is determined in step S93. Opening amount P of the electric expansion valve 11
It is determined whether or not V1 is smaller than the determination valve opening PVtgt.

If the determination in step S93 is No, the process returns to the start without performing any processing. If the determination is Yes, the outdoor ECU 61 determines in step S95 that the indoor ECU 51
To increase the valve opening PV1 of the electric expansion valve 11 with a predetermined increase PVa.

As a result, the flow rate of the refrigerant increases on the indoor unit UH1 side to improve the cooling capacity, while the load increases on the outdoor unit 3 side.

If there is a load margin when returning to the start, the outdoor ECU 61 proceeds to step S75.
Since the determination in S81 is Yes, 1 is added to the control variable i in step S97. If the determination in step S87 is No, the outdoor ECU 61 determines in step S89 that the indoor unit UH2 having the second highest room temperature Tr among the rooms.
Search for. Thereafter, the outdoor ECU 61 determines whether or not the indoor unit UH2 is operating in step S91. If this determination is Yes, the valve opening amount PV2 of the electric expansion valve 11 of the indoor unit UH2 is determined in step S93. Is smaller than the determination valve opening amount PVtgt.

If the determination in step S93 is Yes, the outdoor ECU 61 determines in step S61 that the indoor E
A control command is output to the CU 51 to increase the valve opening PV2 of the electric expansion valve 11 by a predetermined increase PVa.

When there is a load margin, the outdoor ECU 61 also controls the refrigerant flow rate for the other indoor units 1 in the same procedure. Then, by the end of the refrigerant flow control of all the indoor units 1, the control variable i exceeds the installed number N,
If the determination in step S87 is Yes, the outdoor ECU 6
In step S99, the second switching flag FCHG2 is set to 1, the third start flag Fst3 and the third set flag Fset
3 is set to 0.

If there is a load margin at the time when the flow returns to the start after finishing the refrigerant flow control, the outdoor ECU 61 determines that the determination in step S73 is Yes, so the fourth set flag Fset4 is set in step S101 in FIG. Is 1 or not. The fourth set flag Fset4 is a flag indicating that the determination rotation speed described below has been set, and its initial value is set to 0. Since the first determination in step S101 is No, the outdoor ECU 61 sets the determination rotational speed NFtgt (rpm) of the electric fan 9 for returning to the steady load in step S103, and then sets the fourth set flag in step S105. Fset4 is set to 1. still,
The determination rotation speed NFtgt may be obtained by a calculation based on the current average rotation speed NFave of each electric fan 9, or may be determined in advance by RO
A value stored in M may be used.

When the setting of the determination rotational speed NFtgt is completed, the outdoor ECU 61 determines in step S107 that the fourth start flag F
It is determined whether or not st4 is 1. Fourth start flag Fst4
Is a flag indicating that the air volume control has been started to return to the normal operation, and its initial value is set to 0. Since the first determination in step S107 is No,
The outdoor ECU 61 sets the control variable i having an initial value of 0 to 1 in step S109, and then sets the fourth start flag Fst4 to 1 in step S111.

Next, the outdoor ECU 61 proceeds to step S1.
At 13, it is determined whether or not the control variable i exceeds the number N of the installed indoor units 1. Then, since this determination is No for the first time (i = 1), the outdoor ECU 61 searches for an indoor unit UHi (= UH1) having the highest room temperature Tr among the rooms in step S115. Thereafter, the outdoor ECU 61 determines whether or not the indoor unit UH1 is operating in step S117. If the determination is No, the process returns to the start without performing any processing. If the determination is Yes, the process proceeds to step S119. It is determined whether or not the rotation speed NF1 of the electric fan 9 of the indoor unit UH1 is smaller than the determination rotation speed NFtgt.

If the determination in step S119 is No, the process returns to the start without performing any processing. If the determination is Yes, the outdoor ECU 61 proceeds to step S121 and the indoor ECU 5 returns to step S121.
1 to output a control command to increase the rotation speed NF1 of the electric fan 9 by a predetermined increase amount NFa.

As a result, the amount of air blown to the indoor heat exchanger 7 is increased on the indoor unit UH1 side to improve the cooling capacity, while the load on the outdoor unit 3 is reduced. At this time, since the supply amount of the refrigerant has already increased, the liquid refrigerant is prevented from being completely vaporized at a position in the middle of the indoor heat exchanger.

If there is a load margin when returning to the start, the outdoor ECU 61 proceeds to step S10.
Steps S12 and S107 are determined as Yes.
In step 3, 1 is added to the control variable i. Then, step S11
If the determination in Step 3 is Yes, the outdoor ECU 61 searches the indoor unit UH2 having the second highest room temperature Tr among the rooms in Step S115. Then, the outdoor ECU 61
Determines in step S117 whether or not the indoor unit UH2 is in operation. If the determination is Yes, the rotational speed N of the electric fan 9 of the indoor unit UH2 is determined in step S119.
It is determined whether or not F2 is smaller than the determination rotation speed NFtgt.

If the determination in step S119 is Yes, the outdoor ECU 61 outputs a control command to the indoor ECU 51 in step S121 to increase the rotation speed NF2 of the electric fan 9 by a predetermined increase amount NFa. .

When there is a load margin, the outdoor ECU 61 controls the air flow to the other indoor units 1 in the same manner. When the control variable i exceeds the number N of installations due to the end of the air volume control of all the indoor units 1 and the determination in step S113 is Yes, the outdoor ECU 61
Sets the second switching flag FCHG2, the fourth start flag Fst4, and the fourth set flag Fset4 to 0 in step S125.

If there is still a load margin at the time when the flow is returned to the start after finishing the air volume control, this time step S73
Is determined again as No, the outdoor ECU 61 proceeds to step S75 in FIG. 5 to perform refrigerant flow control. That is, the above-described refrigerant flow rate control and air flow rate control are alternately performed until there is no more load margin, and gradually return to the steady operation. At this time, the determination in step S75 in the refrigerant flow rate control and the step S101 in the air flow rate control are performed.
Therefore, the determination opening amount PVtgt of the electric expansion valve 11 and the determination rotation speed NFtgt of the electric fan 9 are newly set each time.

On the other hand, if the overload state is eliminated during the overload elimination or if the load margin is lost during the return to the normal operation, the determinations in steps S7 and S9 are both No, and the outdoor ECU
61 continues the refrigerant flow rate control or the air flow rate control at that time. Then, when an overload state occurs or a load margin occurs due to a change in the operation state or the like, the refrigerant flow rate control and the air flow rate control are restarted to eliminate the overload or return to the normal operation.

When the operation of the compressor 13 is stopped during overload elimination or during normal operation return, the outdoor ECU 61
In step S131, the control of the flow rate of the refrigerant or the control of the air flow is stopped, and in step S133, various flags are initialized. Thus, when the compressor 13 is restarted, the refrigerant flow rate control and the air flow rate control are performed again according to the load state.

As described above, in the above-described embodiment, when the outdoor unit is overloaded, the flow rate and the flow rate of the refrigerant are alternately reduced, and when the load margin occurs, the flow rate of the refrigerant is reduced. And the amount of air blow are alternately performed.
Therefore, when the overload is resolved or when the operation returns to the normal operation, the refrigerant is completely prevented from being in a heated gas state in the middle of the indoor heat exchanger, and the temperature of the indoor air passing through the indoor heat exchanger is reduced. Could be kept relatively low. Also,
When overload is eliminated, priority is given to indoor units with low indoor air temperature, and when returning to normal operation, priority is given to indoor units with high indoor air temperature, so that the difference in indoor temperature between each room is reduced. I was able to.

The description of the specific embodiment has been completed.
The present invention is not limited to this embodiment. For example, in the above-described embodiment, when the overload is eliminated, the flow rate of the refrigerant is reduced after the flow rate is reduced, and when returning to the normal operation, the flow rate is reduced after the flow rate of the refrigerant is reduced. May be reversed. In the above embodiment, the present invention is applied to a gas heat pump type multi-type package air conditioner. However, the present invention can be applied to an inverter type and various air conditioners having different unit arrangements. Further, the specific configuration of the devices and the specific procedure of the control can be appropriately changed without departing from the spirit of the present invention.

[0069]

As described above, according to the air conditioner of the present invention, when the outdoor unit falls into an overloaded state, the processing for reducing the flow rate of the refrigerant and the air flow rate until the overloaded state is eliminated. And the process of reducing the flow rate are alternately performed, so that there is no imbalance between the flow rate of the refrigerant and the flow rate in the indoor heat exchanger.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an air conditioner according to the present invention.

FIG. 2 is a control flowchart according to the embodiment.

FIG. 3 is a control flowchart according to the embodiment.

FIG. 4 is a control flowchart according to the embodiment.

FIG. 5 is a control flowchart according to the embodiment.

FIG. 6 is a control flowchart according to the embodiment.

[Description of Signs] 1 Indoor unit 3 Outdoor unit 7 Indoor heat exchanger 9 Electric fan 11 Electric expansion valve 13 Compressor 25 Gas engine 51 Indoor ECU 53 Room temperature sensor 61 Outdoor ECU 63 Pressure sensor 65 Fuel flow sensor

Claims (4)

[Claims] An air conditioner comprising: an outdoor unit having a compressor and an outdoor heat exchanger; and an indoor unit having an expansion valve, an indoor heat exchanger, and a blower, wherein the outdoor unit is in a cooling operation. Load detection means for detecting the load of the air; expansion valve driving means for driving the expansion valve so as to increase or decrease the flow rate of refrigerant flowing through the indoor heat exchanger; and transmission of indoor air passing through the indoor heat exchanger. In order to increase or decrease the air volume, blower driving means for driving the blower, and when the outdoor unit is determined to be in an overloaded state from the detection result of the load detecting means, the expansion valve driving means and the blower driving means are controlled. Until the overload state is eliminated, an overload eliminating unit that alternately performs a process of reducing the refrigerant flow rate and a process of decreasing the blown air amount, Air conditioner that. 2. An air conditioner including an outdoor unit having a compressor and an outdoor heat exchanger, and an indoor unit having an expansion valve, an indoor heat exchanger, and a blower, wherein the outdoor unit is in a cooling operation. Load detection means for detecting the load of the air; expansion valve driving means for driving the expansion valve so as to increase or decrease the flow rate of refrigerant flowing through the indoor heat exchanger; and transmission of indoor air passing through the indoor heat exchanger. In order to increase or decrease the air volume, blower driving means for driving the blower, and when the outdoor unit is determined to be in an overloaded state from the detection result of the load detecting means, the expansion valve driving means and the blower driving means are controlled. And an overload elimination means for repeatedly performing a process of reducing the flow rate of the refrigerant by a predetermined amount after reducing the blowing amount by a predetermined amount until the overload state is eliminated. An air conditioner characterized by and. 3. An air conditioner comprising: an outdoor unit having a compressor and an outdoor heat exchanger; and a plurality of indoor units having an expansion valve, an indoor heat exchanger, and a blower, wherein the air conditioner is operated during a cooling operation. Load detection means for detecting the load of the outdoor unit; indoor temperature detection means for detecting the indoor temperature of the room in which the indoor unit is installed; and the expansion for increasing or decreasing the flow rate of the refrigerant flowing through the indoor heat exchanger. Expansion valve driving means for driving a valve; blower driving means for driving the blower so as to increase or decrease the amount of indoor air passing through the indoor heat exchanger; and the outdoor unit based on a detection result of the load detection means. If it is determined that the overload state, it controls the expansion valve drive means and the blower drive means, until the overload state is resolved, the detection result of the room temperature detection means The overload eliminating means for alternately performing the process of decreasing the flow rate of the refrigerant and the process of decreasing the amount of blown air in preference to a unit having a lower temperature of the indoor air among the plurality of indoor units. A characteristic air conditioner. 4. An air conditioner comprising: an outdoor unit having a compressor and an outdoor heat exchanger; and a plurality of indoor units having an expansion valve, an indoor heat exchanger, and a blower, wherein the air conditioner is operated during a cooling operation. Load detection means for detecting the load of the outdoor unit; indoor temperature detection means for detecting the indoor temperature of the room in which the indoor unit is installed; and the expansion for increasing or decreasing the flow rate of the refrigerant flowing through the indoor heat exchanger. Expansion valve driving means for driving a valve; blower driving means for driving the blower so as to increase or decrease the amount of indoor air passing through the indoor heat exchanger; and the outdoor unit based on a detection result of the load detection means. If it is determined that the overload state, it controls the expansion valve drive means and the blower drive means, until the overload state is resolved, the detection result of the room temperature detection means Overload eliminating means for repeating the process of reducing the flow rate of the refrigerant by a predetermined amount after decreasing the blowing amount by a predetermined amount, with priority given to a unit having a lower indoor air temperature among the plurality of indoor units. An air conditioner characterized by that: