Refrigeration – Automatic control – Diverse – cascade or compound refrigeration-producing system
Reexamination Certificate
2001-09-28
2003-02-18
Esquivel, Denise L. (Department: 3744)
Refrigeration
Automatic control
Diverse, cascade or compound refrigeration-producing system
C062S231000
Reexamination Certificate
active
06519957
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an air conditioner, and more particularly, the present invention relates to a method for controlling a plurality of compressors in an air conditioner to which a multi-compressor is applied in a manner such that a plurality of compressors are adopted as a compressing means for compressing refrigerant to allow an air conditioner to operate efficiently.
2. Description of the Related Art
FIG. 1
is a systematic view illustrating a construction of a conventional air conditioner.
Referring to
FIG. 1
, the conventional air conditioner includes a compressor
11
for compressing refrigerant, a condenser
12
for removing heat from compressed refrigerant and dissipating removed heat to the outside, an expander
13
for expanding liquid refrigerant of a high pressure, and an evaporator
14
for evaporating expanded refrigerant to absorb heat so that a room temperature can be lowered. The refrigerant that passes through the evaporator
14
, is fed back into the compressor
11
to complete the cycle. Since the condenser
12
and the evaporator
14
are equipped with fans thereby exposed to wind current, heat exchange can be smoothly executed.
The operation of the conventional air conditioner according to the aforementioned construction is described hereinafter. As mentioned above, when the refrigerant is compressed by the compressor
11
, a vaporous refrigerant of the high temperature and pressure is discharged from the compressor
11
. The liquid refrigerant of a high pressure is discharged from the condenser
12
as the vaporous refrigerant of high temperature and pressure is deprived of heat in the condenser
12
, and the liquid refrigerant, which has been passed through the condenser
12
, is expanded by the expander
13
becoming the refrigerant of low temperature and pressure. In the evaporator
14
, the heat is transferred to the refrigerant of the low temperature expanded by the expander
13
, causing the temperature of the area surrounding the evaporator
14
to decrease. Thus, the function of the air conditioner has been fully performed. The refrigerant that consumed the heat while passing through the evaporator
14
, is fed back into the compressor
11
to be compressed again.
On the other hand, the air conditioner as described above in which a constant-speed compressor is adopted as the compressor, a room temperature is lowered when the air conditioner is operated by power supplied thereto, and the heat is quickly absorbed and removed by the evaporator
14
and the condenser
12
, respectively. When the room temperature reaches the temperature set up in advance by a user and the room temperature is longer needs to be lowered, then the compressor
11
, the evaporator
14
and the condenser
12
stop operating causing the room temperature to rise again.
FIG. 2
is a graph illustrating a room temperature change in a conventional air conditioner that adopts a constant-speed compressor. Referring to
FIG. 2
, an initial operation of the air conditioner rapidly drops the room temperature, and if the room temperature falls below the set temperature T
1
and reaches the lower limit temperature T
2
due to a rapid cooling occurrence, the operation of the air conditioner is interrupted (see section A).
Further, as the compressor
11
and the other parts of the air conditioner stop running at the lower limit temperature T
2
, the operation of the air conditioner is interrupted. Although the inside heat is not discharged to the outside, the room temperature rises as the heat is transferred to the inside of the room from the outside. Thereafter, when the room temperature rises beyond the set temperature T
1
and reaches the upper limit temperature T
3
, the compressor
11
starts to operate again (see section B). As the room temperature reaches the upper limit temperature T
3
and the compressor
11
and the other parts of the air conditioner begins operate again, the room temperature drops. Thereafter, as a room temperature drops below the set temperature T
1
and reaches the lower limit temperature T
2
again, the compressor
11
is deactivated, and heat discharge to the outside is suspended (see section C).
In the above descriptions, other than the initial operation period, the section A, the section B process in which the compressor
11
and other parts are deactivated causing a room temperature rises and the section C process in which the compressor
11
and the other parts are in an operation mode to make a room temperature to drop, are repeated. In this way, a room temperature is adequately adjusted. Hence, even if the air conditioner is in the operation mode, from the set temperature T
1
the room temperature continues to shift between the upper limit temperature T
3
and the lower limit temperature to maintain the room temperature.
This phenomenon where a room temperature fluctuates within a predetermined range between T
2
and T
3
while the air conditioner is operated, is called a hunting phenomenon. This hunting phenomenon results the room temperature to be unstably maintained, causing an inconvenience to the user of the air conditioner.
Although it may be possible to reduce the range between the lower limit temperature T
2
and the Upper limit temperature T
3
to minimize the temperature changes sensed by the user, frequent deactuations of the compressor
11
is resulted. Moreover, these frequent deactuations of the compressor
11
result in a problem in terms of efficiency since a great amount of energy is required for initial actuating of the compressor
11
. Thus, reducing the hunting phenomenon may result in increase of the power consumption.
To cope with the aforementioned problem, a method for reducing the hunting phenomenon to ensure delightfulness and comfortableness of the user while reducing power consumption has been introduced. In this method, instead of the constant-speed compressor, a variable-speed compressor which is equipped with an inverter circuit, is adopted. By this, a compressing capability of a compressor can be changed depending upon a heat discharging load, in a manner such that the compressor is not frequently deactuated.
FIG. 3
is a chart for explaining an actuation of a conventional variable-speed compressor which is equipped with an inverter circuit.
Referring to
FIG. 3
, after an air conditioner is initially operated, if a difference between a set temperature which is set in advance by a user and a room temperature is no less than 2.5° C., heat must be quickly discharged to the outside, and, to this end, the variable-speed compressor is actuated at a frequency of H
6
which is a highest frequency under which the variable-speed compressor can be actuated. If the difference is between 2.0 and 2.49° C., the variable-speed compressor is actuated at a frequency of H
5
which is lower, by one step, than H
6
. Consequently, as a difference between the set temperature and a room temperature is gradually decreased, an actuating frequency of the variable-speed compressor is decreased. That is, if a difference is between 0 and 0.49° C., the variable-speed compressor is actuated at a frequency of H
1
which is a lowest frequency under which the variable-speed compressor can be actuated. Hence, the air conditioner is operated while an actuating frequency of the variable-speed compressor is changed depending upon a cooling load.
In the air conditioner to which the variable-speed compressor is applied, since a temperature is gradually and smoothly changed, the hunting phenomenon does not occur, and power consumption due to repetitive on/off switching of the compressor can be avoided.
However, the air conditioner, having applied thereto the variable-speed compressor, has a drawback in that, since the air conditioner includes the inverter circuit and the variable-speed compressor so as to be speed-variably controlled in its operation, a manufacturing cost is increased. Due to this drawback, the air conditioner having the variable-speed compressor is hardly used unless an air
Huh Deok
Ryu Yun Ho
Birch & Stewart Kolasch & Birch, LLP
Esquivel Denise L.
LG Electronics Inc.
Norman Marc
LandOfFree
Method for controlling air conditioner having multi-compressor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for controlling air conditioner having multi-compressor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling air conditioner having multi-compressor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3162769