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The present invention relates to a thermohygrostat-type
air conditioner with means for controlling evaporation
temperature, and more particularly to a low
power-consumption air conditioner, an evaporator of
which has a return pipe maintained at a preset
temperature to enable stable control of indoor
temperature and humidity.
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When a general air conditioner is operated at low
temperature and low humidity, a designed temperature
difference of 5°C between an air-out temperature and
a cooling coil pipe of an evaporator of the air
conditioner is usually maintained. When the
evaporator having a low temperature intercommunicates
with the indoor high-temperature air, it would absorb
water molecules in the indoor air to produce water drops,
so as to achieve the purpose of dehumidifying. However,
this type of freeze dehumidification tends to cause
a surface temperature of the cooling coil pipe lower
than the freezing temperature that results in frosting
and freezing on, surfaces of a return pipe of the
evaporator and prevents the air conditioner from stably
controlling the dehumidification and the indoor
humidity.
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Fig. 3 is a block diagram showing an internal structure
of a general air conditioner capable of stably
maintaining a fixed humidity. The air conditioner
mainly internally includes an
evaporator 82 having a
return pipe 821, and a
chemical dehumidifier 90 provided
near the
return pipe 821. The
chemical dehumidifier
90 includes:
- a dehumidifying wheel 91 located above an outer pipe
wall of the return pipe 821 for absorbing surplus
moisture on the return pipe 821;
- an electric heater 92 provided to one side of the
dehumidifying wheel 91 for heating and drying the
moisture absorbed by the dehumidifying wheel 91; and
- at least one set of air feeder 93 provided at an air
outlet of the dehumidifying wheel 91 for sending out
moisture produced by the dehumidifying wheel 91 during
drying.
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In the main dehumidification principle employed by the
chemical dehumidifier 90, the surplus moisture on the
return pipe 821 is absorbed using the dehumidifying
wheel 91 until the latter is saturated. Then, the
electric heater 92 is heated to dry the moisture for
the dehumidifying wheel 91 to proceed with the next
cycle of dehumidification. However, while the
chemical dehumidifier 90 proceeds with the drying by
heating, it is also necessary to ensure the air-out
of the evaporator has a temperature maintained at a
preset value'. Thus, a compressor 81 of the air
conditioner still has to keep operation at a high speed
for a condenser 80 to provide more refrigerant to the
evaporator 82. Therefore, it can be found that the use
of the chemical dehumidifier 90 would cause double waste
of energy by the air conditioner separately at the time
the moisture produced by the dehumidifying wheel 91
is electrically heated and dried, and the condenser
80 consumes more power to reduce the temperature of
the refrigerant sent to the evaporator 82 to balance
a temperature difference produced at heating of the
heater 92. Therefore, although the provision of the
chemical dehumidifier 90 enables the air conditioner
to achieve the function of reducing temperature and
humidity, it also increases the manufacturing cost and
power consumption of the air conditioner.
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It is therefore necessary to improve the conventional
air conditioner having the chemical dehumidifier
associated therewith.
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A primary object of the present invention is to provide
an air conditioner that does not require a chemical
dehumidifier and may effectively adjust refrigerant
flow using internal structures, so that a cooling coil
pipe thereof may be effectively controlled to maintain
at a preset temperature. In this manner, a return pipe
of an evaporator in the air conditioner may have a
temperature not lower than the preset temperature.
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Another object of the present invention is to provide
a low power-consumption and low manufacturing cost
thermostat.
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These objects are achieved with the features of the claims.
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The presentinventionrelatestoathermohygrostat-type
air conditioner with means for controlling evaporation
temperature, being characterized in that a temperature
detector is mounted on a return pipe between an
evaporator and a compressor for detecting a current
temperature of the coiled return pipe from time to time.
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The detected temperature value is sent to a temperature
controller adapted to control operation of the
compressor, so that the temperature controller may
regulate a rotating speed of the compressor based on
the current temperature of the coiled return pipe and
thereby maintains the return pipe at a preset
temperature. In this manner, an evaporation
temperature of a cooling coil pipe may be effectively
controlled, and a stable humidity may be maintained
in air conditioning with a low-cost and high-efficient
apparatus.
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To achieve the above objects, the air conditioner of
the present invention includes:
- at least one set of evaporator, each of which has an
expansion valve provided on a refrigerant input pipe
near an inlet thereof, and a return pipe connected to
a refrigerant output thereof;
- at least one set of compressor, each of which is connected
to the return pipe of one corresponding evaporator;
- at least one set of condenser, each of which has an
output connected to a high-pressure high-temperature
gaseous refrigerant output pipe of one corresponding
compressor to lower the temperature of the refrigerant;
and
- a temperature-control circuit connected to each
compressor and the return pipe of each evaporator for
detecting an existing temperature of the return pipe,
and comparing the detected temperature with a preset
temperature for controlling the rotary speed of the
compressor.
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Via the temperature detector on the return pipe of the
evaporator, the temperature control circuit determines
whether the temperature of the return pipe is close
to the present temperature. That is, when it is
detected the temperature of the return pipe of the
evaporator is lower than the preset temperature, the
control circuit outputs a signal via a frequency
converter to reduce the rotary speed of the compressor
and thereby raises the temperature of cool air output
from the evaporator and accordingly increases the
temperature at the pipe wall of the return pipe. In
this manner, it can be ensured the return pipe would
not have a temperature lower than the preset temperature
and the phenomenon of frosting on the surfaces of the
return pipe may be eliminated.
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With the same structure as the
above-described air conditioner, the thermostat
includes a temperature control circuit having low
power-consumption temperature controller, frequency
converter, and temperature detector, and can therefore
save the power consumption and have a manufacturing
costl ower than the conventional chemical dehumidifier.
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The structure and the technical means adopted by the
present invention to achieve the above and other objects
can be best understood by referring to the following
detailed description of the preferred embodiments and
the accompanying drawings, wherein
- Fig. 1 is a block diagram of an air conditioner according
to a first preferred embodiment of the present
invention;
- Fig. 2 is a block diagram of an air conditioner according
to a second preferred embodiment of the present
invention; and
- Fig. 3 is a block diagram of a conventional air
conditioner using a chemical dehumidifier.
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The present invention relates to an air conditioner
having low power consumption and ensuring stable
control of temperature. That is, the present invention
relates to an air conditioner providing the function
of a thermohygrostat without using a chemical
dehumidifier.
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Please refer to Fig. 1 that is a block diagram of an
air conditioner according to the present invention.
As shown, the air conditioner mainly includes the
following components:
- at least one set of evaporator 31, each of which has
an expansion valve 51 provided on a refrigerant input
pipe near an inlet thereof, and has a return pipe 41
connected to a refrigerant output thereof;
- at least one set of compressor 21, each of which is
connected to the return pipe 41 of one corresponding
evaporator 31;
- at least one set of condenser 11, each of which has
an output connected to a high-pressure high-temperature
gaseous refrigerant output pipe of one corresponding
compressor 21, in order to lower the temperature of
the refrigerant; and
- a temperature-control circuit 7 connected between each
compressor 21 and the return pipe 41 of a corresponding
evaporator 31 for detecting an existing temperature
of the return pipe 41, and the detected temperature
being compared with a preset temperature for
controlling movements of the compressor 21. The
temperature-control circuit 7 includes:
- a temperature controller 71, an output of which is
connected to the expansion valve 51 of each evaporator
31 for controlling the amount of refrigerant input via
the expansion valve 51 to the corresponding evaporator
31; and another output of which is connected to each
heat bypass valve 61 for controlling the compressor
21, so that a part of surplus heat of the compressor
21 is automatically bypassed to a low-pressure side
to further stabilize the evaporation temperature of
the system;
- at least one set of temperature detector 72, each of
which is mounted on a surface of one corresponding return
pipe 41, and has an output connected to said temperature
controller 71; and
- at least one set of frequency converter 731, each of
which has an input connected to the above-mentioned
temperature controller 71, and an output connected to
one corresponding compressor 21 for controlling a
rotary speed of the compressor 21.
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A more detailed description of an operating procedures
of the above-mentioned embodiment of the present
invention will now be provided with reference to the
accompanying drawings. Please refer to Fig. 1 in which
an air conditioner according to a first preferred
embodiment of the present invention is shown. As shown,
the air conditioner includes two sets of evaporators
31, 32, two sets of condensers 11, 12, two sets of
compressors 21, 22, and a set of temperature control
circuit 7 on which a temperature value absolutely not
lower than a freezing temperature is preset. When the
air conditioner is initially started, there is a
relatively high indoor temperature, and the temperature
detector 72 connected to the return pipe 41 of the
evaporator 31 detects a temperature higher than the
preset temperature value. At this point, the
temperature controller 71 would control the first and
the second compressor 21, 22 via two corresponding
frequency converters 731, 732. That is, the first
compressor 21 is caused to operate at a full speed while
the second compressor 22 is caused to operate at a normal
speed, so that the indoor temperature may be lowered
within a short time. And, when the temperature detector
72 detects that the return pipe 42 has a lowered
temperature and a difference between it and the preset
temperature value is only 0.5°C, the temperature
controller 71 would control the frequency converter
731 connected to the first compressor 21 for the first
compressor 21 to slow down and finally return to its
normal operating speed.
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In the event the temperature detector 72 detects that
the return pipe 42 has reached the preset temperature,
the temperature controller 71 would also control the
frequency converter 731 for the first compressor 21
to lower down its rotary speed to a minimum allowable
speed while the second compressor 22 is maintained at
its normal rotary speed. At this point, since the
indoor temperature, is very close to the preset
temperature for the air conditioning, only one
compressor, that is the first compressor 21, is used
as a main power source to circulate the refrigerant.
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When the second compressor 22 keeps operating for the
evaporator 32 to output air having a relatively low
temperature, the temperature detector 72 connected to
the return pipe 42 of the evaporator 32 would detect
a temperature lower than that preset on the temperature
controller 71. Therefore, the temperature controller
71 would reduce the rotary speed of the second compressor
22 via the frequency converter 732 connected to the
second compressor 22. Thereby, the gaseous
refrigerant output from the condenser 12 to the
evaporator 32 is relatively reduced in volume, and the
temperature at an outlet of the evaporator 32 rises
to maintain a surface temperature of the return pipe
42 at the preset temperature value. In other words,
moisture condensed through heat exchange in the air
makes the evaporator 32 having a temperature not lower
than the temperature preset for the return pipe 41,
so that the air conditioner may stably control the
temperature and the humidity.
When a load of the air conditioner is further reduced,
the heat bypass valve 61 controlled by the output of
the temperature controller 71 is used to control the
surplus energy of the compressor 21, so that a part
of the heat is automatically bypassed to the
low-pressure side to further stabilize the evaporation
temperature of the system.
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Please refer to Fig. 2 that shows a second preferred
embodiment of the present invention. The air
conditioner of the second embodiment is generally
structurally similar to the first embodiment, except
that an additional set of refrigerant circulation
system is provided to more quickly reduce the indoor
temperature within a preset time. Similarly, the
additional refrigerant circulation system is provided
on the return pipe 43 of the evaporator 33 with a
temperature detector 72 to detect a temperature on the
return pipe 43 and input the detected value into the
temperature controller 71, so that the temperature
controller 71 determines a difference between the
temperature detected by the temperature detector 72
and the preset temperature value to control the
movements of the compressors 21, 22, 23 based on the
determined difference of temperature. That is, the air
conditioner may stably control the temperature and
humidity through adjusting an output of the
refrigerant.
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From the above description, it is understood the present
invention utilizes simple temperature control circuit
to monitor and control movements of the evaporators
and compressors inside the air conditioner, so that
the return pipes of the evaporators are always
maintained at a temperature higher than the preset
temperature value without the risk of having a frozen
pipe wall. Unlike the conventional air conditioner
that has a compressor consuming increased power, the
air conditioner of the present invention with the
above-described design not only consumes low electric
energy, but also effectively eliminates the problem
of a return pipe having frozen pipe wall through
utilization of surplus heat to dry the return pipe.
Therefore, the present invention enables a general air
conditioner to stably control the humidity at low cost
and low power consumption without mounting the chemical
dehumidifier.
