US20070079620A1

US20070079620A1 - Unitary air conditioner

Info

Publication number: US20070079620A1
Application number: US11/400,207
Authority: US
Inventors: Won Lee
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2005-10-10
Filing date: 2006-04-10
Publication date: 2007-04-12
Also published as: KR20070039764A; KR100719851B1

Abstract

A unitary air conditioner includes a thermostat for generating an operation signal, an outdoor equipment operated according to an operation signal of the thermostat, an indoor equipment whose indoor fan is driven according to an operation signal of the thermostat, and an indoor fan control unit for increasing air volume after the indoor fan is driven at a rated air volume. After being driven at a rated air volume, the indoor fan is driven at an air volume higher than the rated air volume, thereby realizing a power saving operation with good energy efficiency.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a unitary air conditioner which is mainly used in North America, and more particularly, to a unitary air conditioner capable of realizing a super power saving operation which can maximize energy efficiency as the air volume of an indoor fan increases when the indoor fan is continuously driven for a predetermined time at a rated air volume.
2. Background of the Related Art
FIG. 1 is a block diagram of a conventional 1-stage unitary air conditioner. FIG. 2 is a control circuit block diagram of the conventional 1-stage unitary air conditioner, which is a view showing a main circuit terminal connection state.
When the unitary air conditioner as shown in FIGS. 1 and 2 receives an operation (Y) or stop signal from a 1-stage thermostat 2, a 1-stage outdoor equipment 4 installed outdoors and a 1-stage indoor equipment 6 installed indoors are operated or stopped.
Such a 1-stage unitary air conditioner is an air conditioning system which is used in most houses in North America including the US. The 1-stage outdoor equipment 4 and the 1-stage indoor equipment 6 are operated (ON) or stopped (OFF) with a single unit operating capacity.
FIG. 3 is a control circuit block diagram of a conventional 2-stage unitary air conditioner, which is a view showing a main circuit terminal connection state.
The 2-stage unitary air conditioner as shown in FIG. 3 is provided with a 2-stage thermostat 10 generating a HIGH (Y1) or LOW (Y2) operation stage signal. A 2-stage outdoor equipment 12 and a 2-stage indoor equipment 14 are operated in HIGH and LOW modes while alternating their operating capacity according to a HIGH (Y1) or LOW (Y2) operation signal of the 2-stage thermostat 10.
However, the unitary air conditioner according to the conventional art has a problem that products of different stages cannot be applied in connection with each other because indoor equipment and outdoor equipments can work with each other only when their stage is consistent with each other.
That is, as stated above, the 1-stage unitary air conditioner is made operable by connecting only the 1-stage outdoor equipment 4 and the 1-stage equipment 6 to the 1-stage thermostat 2, and the 2-stage unitary air conditioner is made operable by connecting only the 2-stage outdoor equipment 12 and the 2-stage equipment 14 to the 2-stage thermostat 10. Thus there is a limit in the extended application of the products.
Furthermore, the unitary air conditioner generally has low energy efficiency since the indoor fan of the indoor equipment is driven only with a rated air volume with temperature, humidity and so on taken into account.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to solve the foregoing conventional problems, and an object of the present invention is to provide a unitary air conditioner which can be used along with parts of different stages by constructing an indoor equipment and an outdoor equipment so as to be operable in conjunction with each other even if their stages are not consistent with each other.
Furthermore, another object of the present invention is to provide a unitary air conditioner which enables an indoor equipment to be operated in multiple stages without replacing the indoor equipment by installing an indoor fan control unit so that an indoor fan of the indoor equipment may be driven in conjunction with an operation state of a volume-variable outdoor equipment such as a 2-stage outdoor equipment.
Furthermore, yet another object of the present invention is to provide a unitary air conditioner which can maximize energy efficiency by installing an indoor fan control unit so as to increase air volume after an indoor fan of an indoor equipment is driven at a rated air volume.
To accomplish the above objects, there is provided a unitary air conditioner according to one aspect of the present invention, including: a thermostat for generating an operation signal; an outdoor equipment operated according to an operation signal of the thermostat; an indoor equipment whose indoor fan is driven according to an operation signal of the thermostat; and an indoor fan control unit for increasing air volume after the indoor fan is driven at a rated air volume.
The indoor fan control unit controls the air volume of the indoor fan to be maintained at a rated air volume if the rated air volume of the indoor fan is the highest air volume of the indoor fan.
If an operation state of the outdoor equipment is changed, the indoor fan control unit controls the indoor fan to be driven at a rated air volume set according to a changed operation state of the outdoor equipment.
The indoor fan is driven in a stage higher than a 2-stage, and the indoor fan control unit increases the air volume of the indoor fan to a rated air volume of a higher stage after the indoor fan is driven at a rated air volume of a predetermined stage.
The thermostat generates a single or plurality of operation signals.
The outdoor equipment is a volume-variable outdoor equipment in which operation stages of a compressor and of an outdoor fan are variable.
The indoor equipment is operated in a single or multiple operation stages.
The indoor fan control unit is comprised of a relay switch.
To accomplish the above objects, there is provided a unitary air conditioner according to another aspect of the present invention, including: a thermostat for generating an operation signal; an outdoor equipment operated according to an operation signal of the thermostat; an indoor equipment whose indoor fan is driven according to an operation signal of the thermostat; and an indoor fan control unit for increasing the air volume of the indoor fan once the indoor fan is continuously driven for a predetermined time with a rated air volume
The indoor fan control unit controls the air volume of the indoor fan to be maintained at a rated air volume if the rated air volume of the indoor fan is the highest air volume of the indoor fan.
If an operation state of the outdoor equipment is changed, the indoor fan control unit controls the indoor fan to be driven at a rated air volume set according to a changed operation state of the outdoor equipment.
The indoor fan is driven in a stage higher than a 2-stage, and the indoor fan control unit increases the air volume of the indoor fan to a rated air volume of a higher stage after the indoor fan is driven at a rated air volume of a predetermined stage.
The thermostat generates a single or plurality of operation signals.
The outdoor equipment is a volume-variable outdoor equipment in which operation stages of a compressor and of an outdoor fan are variable.
The indoor equipment is operated in a single or multiple operation stages.
The indoor fan control unit is comprised of a relay switch.
To accomplish the above objects, there is provided a unitary air conditioner according to still another aspect of the present invention, including: a thermostat for generating an operation signal; an outdoor equipment operated according to an operation signal of the thermostat; an indoor equipment whose indoor fan is driven according to an operation signal of the thermostat; and an indoor fan control unit for increasing the air volume of the indoor fan after the indoor fan is driven at a rated air volume, controlling the air volume of the indoor fan to be maintained at a rated air volume if the rated air volume of the indoor fan is the highest air volume of the indoor fan, and controlling the indoor fan to be driven at a rated air volume set according to a changed operation state of the outdoor equipment if an operation state of the outdoor equipment is changed.
If the indoor fan is continuously driven for a predetermined time with the rated air volume, the indoor fan control unit increases the air volume of the indoor fan.
The indoor fan is driven in a stage higher than a 2-stage, and the indoor fan control unit increases the air volume of the indoor fan to a rated air volume of a higher stage after the indoor fan is driven at a rated air volume of a predetermined stage.
The indoor fan control unit is comprised of a relay switch.
The thus-constructed unitary air conditioner according to the present invention is constructed such that the 1-stage indoor equipment is made operable in conjunction with the volume-variable outdoor equipment or the 2-stage thermostat. Thus, the 1-stage indoor equipment can be used in conjunction with a product of a different stage, and the indoor fan can be variably controlled by the indoor fan control unit, thereby realizing a more efficient system.
Furthermore, the unitary air conditioner of the invention is constructed such that the indoor fan is variably controlled by the indoor fan control unit. Thus, after being driven at a rated air volume, the indoor fan is driven at an air volume higher than the rated air volume under the condition that an operation signal of the thermostat or an operational stage of the volume-variable outdoor equipment is constant. This increases evaporation temperature and decrease the power consumption of the compressor, thereby realizing a super power saving operation with better energy efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
FIG. 1 is a block diagram of a conventional 1-stage unitary air conditioner;
FIG. 2 is a control circuit block diagram of the conventional 1-stage unitary air conditioner, which is a view showing a main circuit terminal connection state;
FIG. 3 is a control circuit block diagram of a conventional 2-stage unitary air conditioner, which is a view showing a main circuit terminal connection state;
FIG. 4 is a control circuit block diagram of a unitary air conditioner according to a first embodiment of the present invention;
FIG. 5 is a control circuit block diagram of a unitary air conditioner according to a second embodiment of the present invention; and
FIG. 6 is a control circuit block diagram of a unitary air conditioner according to a third embodiment of the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 4 is a control circuit block diagram of a unitary air conditioner according to a first embodiment of the present invention.
The unitary air conditioner according to the first embodiment of the present invention includes: a thermostat 50 installed indoors; an outdoor equipment 60 operated according to an operation signal of the thermostat 50; an indoor equipment 70 whose indoor fan is driven according to an operation signal of the thermostat 50; and an indoor fan control unit 80 for controlling the indoor fan.
The thermostat 50 may be configured in one stage for generating a single operation signal, or in two stages or higher for generating a plurality of operation signals. Hereinafter, the thermostat 50 is restricted to a 1-stage thermostat 50 for the convenience of explanation, and the reference numeral of the 1-stage thermostat 50 is identical to the reference numeral of the thermostat 50.
The aforementioned 1-stage thermostat 50 is constructed to generate only a single operation signal (Y) of the unitary air conditioner. That is, the 1-stage thermostat 50 is operated only in ON/OFF modes.
The outdoor equipment 60 is provided as a volume-variable outdoor equipment 60 which is ON/OFF operated according to a signal of the 1-stage thermostat 50, and whose volume is variable by automatically controlling the operation stage of an compressor and of an outdoor fan according to its operation state determined by its outdoor equipment control unit 62 at the time of operation.
Hereinafter, the volume-variable outdoor equipment 60 is operable in two stages of HIGH and LOW operations and in multiple stages including three stages of HIGH, INTERMEDIATE and LOW operations. For the convenience of explanation, the volume-variable outdoor equipment 60 is limited to the LOW operation stage in which the capacity is 40% or 60% or the HIGH operation stage in which the capacity is 100%, and the reference numeral of the volume-variable outdoor equipment 60 is identical to the reference numeral of the outdoor equipment 60.
The outdoor equipment control unit 62 includes a signal input section 63 for inputting an operation signal of the 1-stage thermostat 50, an operation state determination and control section 64 for recognizing the signal of the signal input section 63 and its operation state, that is, an operation state of the compressor or indoor fan and varying the operational stage into either HIGH or LOW operation stage, and a signal output section 65 for outputting a signal to the indoor fan control unit 80 according to the signal of the operation state determination and control section 64.
Here, the operation state determination and control section 64 stores and recognizes the previous operation state or current operation state of the compressor or of the outdoor fan, and determines and controls the operation stage of the volume-variable outdoor equipment 60 according to its own control algorithm on the basis of the previously stored or recognized operation state at the time of next operation.
That is, as an example of variable control, if the compressor is operated in LOW operation state for more than a predetermined time, the operation state determination and control section 64 changes the operation state to HIGH operation state, and if the previous operation is in the HIGH operation state, it controls the start operation to be in the HIGH operation state regardless of a signal of the 1-stage thermostat 50.
Naturally, it is preferable that the compressor provided at the volume-variable outdoor equipment 60 is a volume-variable inverter type or comprised of a plurality of constant-speed compressors with a predetermined capacity, and is made operable in HIGH and LOW operation stages according to the control of the operation state determination and control section 64.
The indoor equipment 70 also can be configured to be operated in more than two stages as well as one stage. Hereinafter, the indoor equipment 70 is restricted to a 1-stage indoor equipment 70 for the convenience of explanation, and the reference numeral of the 1-stage indoor equipment 70 is identical to the reference numeral of the indoor equipment 70.
The indoor fan provided at the 1-stage indoor equipment 70 can be configured to be driven in more than two stages of HIGH wind and LOW wind or of HIGH wind, MEDIUM wind and LOW wind by an indoor fan motor 74. In this embodiment, the indoor fan is limited to being constructed of two stages in which it is driven only by HIGH wind and LOW wind levels according to the HIGH and LOW operation stages of the volume-variable outdoor equipment 60.
The rated air volume of each stage of the indoor fan of this type is preset so that the indoor temperature, humidity and so on can be conditioned to an optimum state according to the HIGH and LOW operation stages of the volume-variable outdoor equipment 60. For example, in case of LOW wind, the rated air volume of the indoor fan is 400 Cfm per 1 RT, and in case of HIGH wind, the rated air volume thereof is 600 Cfm per 1 RT.
The above-said 1-stage indoor equipment 70 is provided with an indoor equipment control unit 72.
The indoor equipment control unit 72 outputs a control signal to the indoor fan motor 74 upon receipt of signal of the 1-stage thermostat 50, and forwards the signal to the outdoor equipment control unit 62.
The indoor fan control unit 80 may be comprised of a 2-speed kit provided with a relay switch so as to control the HIGH and LOW winds of the indoor fan by controlling the HIGH and LOW of the indoor fan motor 74.
Here, the relay switch selectively connects to a HIGH operation circuit or LOW operation circuit among the driving circuits of the indoor fan motor 74 and switch them.
Preferably, the indoor fan control unit 80 of this type is constructed separately from the indoor equipment control unit 72, such that it can be connected to the driving circuits of the indoor fan motor 74 for use when the 1-stage indoor equipment 70 is used in conjunction with a product of a different stage such as the volume-variable outdoor equipment 60.
The indoor fan control unit 80 increase the air volume of the indoor fan for improving energy efficiency under the condition that the operation stage of the outdoor equipment 60 is not changed after the indoor fan is driven at a predetermined rated air volume preset according to the operation stage of the outdoor equipment 60.
At this time, the indoor fan control unit 80 can increase the air volume of the indoor fan according to the temperature, humidity and desired temperature of the indoor and the continuous driving time of the indoor fan under the condition that the operation stage of the outdoor equipment 60 is constant. Hereinafter, there is a limitation that the air volume of the indoor fan is increased when the indoor fan is continuously driven for a predetermined time (e.g., approximately 30 minutes) at a rated air volume of a predetermined stage.
Moreover, since the rated air volume of the indoor fan is driven only in two stages of HIGH wind and LOW wind, it is preferable that the indoor fan control unit 80 controls the indoor fan to be driven at the HIGH wind level, which is the rated air volume of a higher stage after the indoor fan is driven at the LOW wind level if the rated air volume of the indoor fan is the LOW wind level under the condition that the operation stage of the outdoor equipment 60 is constant.
Moreover, since the rated air volume of the indoor fan is driven only in two stages of HIGH wind and LOW wind, it is preferable that the indoor fan control unit 80 maintains the rated air volume of the indoor fan to be the HIGH wind level even if the indoor fan was continuously driven at the HIGH wind level for a predetermined time if the rated air volume of the indoor fan is the HIGH wind level, which is the highest wind of the indoor fan, under the condition that the operation stage of the outdoor equipment 60 is constant.
Meanwhile, when the operation stage of the outdoor equipment 60 is changed regardless of the air volume of the indoor fan, the indoor fan control unit 80 controls the indoor fan to be driven at a rated air volume corresponding to the changed operation stage of the outdoor equipment 60.
The operation of the thus-constructed unitary air conditioner according to the present invention will now be described.
When the 1-stage thermostat 50 generates an operation signal, the volume-variable outdoor equipment 60 and the 1-stage indoor equipment 70 operate.
At this time, if the volume-variable outdoor equipment 60 is operates in the LOW operation stage according to the determination of the outdoor equipment control unit 62, the indoor fan control unit 80 controls the indoor fan to be driven at the LOW wind level by connecting to the LOW operation circuit of the driving circuits of the indoor fan motor 74 and driving the indoor fan motor 74 at the LOW level.
When the indoor fan is continuously driven for more than a predetermined time in the LOW operation stage, with the volume-variable outdoor equipment 60 being continuously operated in the LOW operation stage, the indoor fan control unit 80 controls the indoor fan to be driven at the HIGH wind level by connecting to the HIGH operation circuit of the driving circuits of the indoor fan motor 74 and driving the indoor fan motor 74 at the HIGH level.
Then, the air volume of the indoor fan is relatively increased under the condition that the operation stage of the volume-variable outdoor equipment 60, that is, the operation capacity thereof, is instant. Therefore, the evaporation degree increases and the compressor power consumption of the volume-variable outdoor equipment 60 decreases, thereby improving energy efficiency.

The following [Table 1] compares the indoor fan being driven at a rated air volume (A) with the indoor fan being driven at an air volume (B) higher than the rated air volume, under the condition that the operation stage of the volume-variable outdoor equipment 60 of a heat pump type unitary air conditioner is identical.

	TABLE 1


	capacity

	12k_130%(B)	12k_130%(B)
sample specification	LEV 174	LEV 172

experimental	description	Heat COP
condition	Temp. ID	20/15
	Temp. OD	7/16

capability		15,396	15,445
(Btu/hr)
	W	4,513	4,527
capability ratio		98.7	99.0
total		1,128.5	1,331.5
COP(W/W)		4.00	3.40
power	indoor fan	39.8	17.5
consumption	outdoor fan	31.0	31.0
(W)	compressor, etc.	1,051.7	1,277.0
	4-way valve	6.0	6.0
indoor fan	air volume (CMM)	13.63	9.96
	RPM	1,757	1,380
outdoor fan	air volume (CMM)	33	33
	RPM	612	612

In Table 1, it is seen that the amount of reduction in the power consumption of the compressor is larger than the amount of increase in the power consumption of the indoor fan due to an increase in the air volume of the indoor fan, resultantly reducing the overall power consumption and increasing the COP.
On the other hand, if the volume-variable outdoor equipment 60 is operated from the LOW operation stage to the HIGH operation stage according to the determination of the outdoor equipment control unit 62, the indoor fan control unit 80 changes the rated air volume of the indoor fan to the HIGH wind level, thereby driving the indoor fan at the HIGH wind level.
At this time, in the case where the rated air volume of the indoor fan is the HIGH wind level, the indoor fan control unit 80 does not increase the air volume of the indoor fan even if the indoor fan was continuously driven at the HIGH wind level for a predetermined time, but maintains the air volume of the indoor fan to be at the HIGH wind level, which is the rated air volume thereof.
Next, the unitary air conditioner according to a second embodiment of the present invention will be described in detail with reference to FIG. 5. Hereinafter, in the description of the unitary air conditioner according to the second embodiment of the present invention, identical and similar constituents described in the first embodiment of the present invention can be omitted in order to avoid a redundant description, thus the first embodiment of the present invention is referenced.
FIG. 5 is a control circuit block diagram of a unitary air conditioner according to a second embodiment of the present invention.
The unitary air conditioner according to the second embodiment of the present invention includes: a 2-stage thermostat 100 for generating a HIGH or LOW operation signal; a volume-variable outdoor equipment 110 operated at HIGH and LOW levels according to the HIGH or LOW operation signal of the 2-stage thermostat 100; a 1-stage indoor equipment 120 whose indoor fan is driven according to the HIGH or LOW operation signal of the 2-stage thermostat 100; and an indoor fan control unit 130 for controlling the indoor fan.
The rated air volume of the indoor fan applied to the 1-stage indoor equipment 120 is set to HIGH wind and LOW wind.
In the unitary air conditioner according to the second embodiment of the present invention, when the 2-stage thermostat 100 generates a LOW operation signal, the volume-variable outdoor equipment 110 is operated at LOW level, and the indoor fan control unit 130 controls the rated air volume of the indoor fan to be the LOW wind level, thereby driving the indoor fan to be the LOW wind level.
When the indoor fan is continuously driven for a predetermined time at the LOW wind level, which is the rated air volume thereof, under the condition that the 2-stage thermostat 100 continuously generates a LOW operation signal or the volume-variable outdoor equipment 100 is continuously operated in the LOW operation level, the indoor fan control unit 130 controls the air volume of the indoor fan to be the HIGH wind level, thereby driving the indoor fan at the HIGH wind level.
On the other hand, if the—stage thermostat 100 generates a HIGH operation signal, the volume-variable outdoor equipment 100 is operated at HIGH level, and the indoor fan control unit 130 controls the rated air volume of the indoor fan to be the HIGH wind, thereby driving the indoor fan at the HIGH wind level. Of course, the indoor fan control unit 130 continuously maintains the air volume of the indoor fan to be the HIGH wind, which is the rated air volume thereof, under the condition that the volume-variable outdoor equipment 110 is continuously operated at the HIGH operation level.
Meanwhile, it is needless to say that the unitary air conditioner according to the present invention is not limited to the first and second embodiments of the present invention, but an indoor equipment of more than two stages as well as a thermostat of more than three stages are applicable.
FIG. 6 is a control circuit block diagram of a unitary air conditioner according to a third embodiment of the present invention. Even when the unitary air conditioner according to the third embodiment of the present invention is a multi type in which at least one indoor equipment 160 is connected to at least one outdoor equipment, an indoor fan control unit comprised of a 2-speed kit can be installed at each indoor equipment 160. A thermostat 170 can be provided for each of the indoor equipments 160 so that each indoor equipment 160 may be operated separately.
The thus-constructed unitary air conditioner according to the present invention is constructed such that the 1-stage indoor equipment is made operable in conjunction with the volume-variable outdoor equipment or the 2-stage thermostat. Thus, the 1-stage indoor equipment can be used in conjunction with a product of a different stage, and the indoor fan can be variably controlled by the indoor fan control unit, thereby realizing a more efficient system.
Furthermore, the unitary air conditioner of the invention is constructed such that the indoor fan is variably controlled by the indoor fan control unit. Thus, after being driven at a rated air volume, the indoor fan is driven at an air volume higher than the rated air volume under the condition that an operation signal of the thermostat or an operational stage of the volume-variable outdoor equipment is constant. This increases evaporation temperature and decrease the power consumption of the compressor, thereby realizing a super power saving operation with better energy efficiency.

Claims

1. A unitary air conditioner, comprising:

a thermostat for generating an operation signal;

an outdoor equipment operated according to an operation signal of the thermostat;

an indoor equipment whose indoor fan is driven according to an operation signal of the thermostat; and

an indoor fan control unit for increasing air volume after the indoor fan is driven at a rated air volume.

2. The unitary air conditioner as claimed in claim 1, wherein the indoor fan control unit controls the air volume of the indoor fan to be maintained at a rated air volume if the rated air volume of the indoor fan is the highest air volume of the indoor fan.

3. The unitary air conditioner as claimed in claim 1, wherein if an operation state of the outdoor equipment is changed, the indoor fan control unit controls the indoor fan to be driven at a rated air volume set according to a changed operation state of the outdoor equipment.

4. The unitary air conditioner as claimed in claim 1, wherein the indoor fan is driven in a stage higher than a 2-stage, and the indoor fan control unit increases the air volume of the indoor fan to a rated air volume of a higher stage after the indoor fan is driven at a rated air volume of a predetermined stage.

5. The unitary air conditioner as claimed in claim 1, wherein the thermostat generates a single or plurality of operation signals.

6. The unitary air conditioner as claimed in claim 5, wherein the outdoor equipment is a volume-variable outdoor equipment in which operation stages of a compressor and of an outdoor fan are variable.

7. The unitary air conditioner as claimed in claim 1, wherein the indoor equipment is operated in a single or multiple operation stages.

8. The unitary air conditioner as claimed in claim 1, wherein the indoor fan control unit is comprised of a relay switch.

9. A unitary air conditioner, comprising:

a thermostat for generating an operation signal;

an indoor fan control unit for increasing the air volume of the indoor fan once the indoor fan is continuously driven for a predetermined time with a rated air volume.

10. The unitary air conditioner as claimed in claim 9, wherein the indoor fan control unit controls the air volume of the indoor fan to be maintained at a rated air volume if the rated air volume of the indoor fan is the highest air volume of the indoor fan.

11. The unitary air conditioner as claimed in claim 9, wherein if an operation state of the outdoor equipment is changed, the indoor fan control unit controls the indoor fan to be driven at a rated air volume set according to a changed operation state of the outdoor equipment.

12. The unitary air conditioner as claimed in claim 9, wherein the indoor fan is driven in a stage higher than a 2-stage, and the indoor fan control unit increases the air volume of the indoor fan to a rated air volume of a higher stage after the indoor fan is driven at a rated air volume of a predetermined stage.

13. The unitary air conditioner as claimed in claim 9, wherein the thermostat generates a single or plurality of operation signals.

14. The unitary air conditioner as claimed in claim 9, wherein the outdoor equipment is a volume-variable outdoor equipment in which operation stages of a compressor and of an outdoor fan are variable.

15. The unitary air conditioner as claimed in claim 9, wherein the indoor equipment is operated in a single or multiple operation stages.

16. The unitary air conditioner as claimed in claim 9, wherein the indoor fan control unit is comprised of a relay switch.

17. A unitary air conditioner, comprising:

a thermostat for generating an operation signal;

an indoor fan control unit for increasing the air volume of the indoor fan after the indoor fan is driven at a rated air volume, controlling the air volume of the indoor fan to be maintained at a rated air volume if the rated air volume of the indoor fan is the highest air volume of the indoor fan, and controlling the indoor fan to be driven at a rated air volume set according to a changed operation state of the outdoor equipment if an operation state of the outdoor equipment is changed.

18. The unitary air conditioner as claimed in claim 17, wherein if the indoor fan is continuously driven for a predetermined time with the rated air volume, the indoor fan control unit increases the air volume of the indoor fan.

19. The unitary air conditioner as claimed in claim 17, wherein the indoor fan is driven in a stage higher than a 2-stage, and the indoor fan control unit increases the air volume of the indoor fan to a rated air volume of a higher stage after the indoor fan is driven at a rated air volume of a predetermined stage.

20. The unitary air conditioner as claimed in claim 17, wherein the indoor fan control unit is comprised of a relay switch.