JPH06147689A - Air conditioning apparatus - Google Patents

Abstract

PURPOSE:To enhance dehumidifying capacity in an intermediate term by disposing first, second heat exchangers in an air conditioning duct and a third heat exchanger out of the duct, and controlling a heat exchanging efficiency of the third exchanger in a state that a cycle for dehumidifying and heating is formed. CONSTITUTION:At the time of dehumidifying and heating, a four-way valve 5 is switched to a position of solid lines. When a temperature of a first heat exchanger 2 is 0 deg.C or lower based on an output of a temperature detector 11, a solenoid valve 9 is closed to prevent freezing. Then, an the valve travel of an electric control type expansion valve 7 is regulated to control a heat absorption quantity of a third heat exchanger 4. That is, the valve travel of the valve 7 is made small in an intermediate term, a heat exchanging efficiency of the exchanger 4 is deteriorated to reduce heat absorption from the outside air and hence an evaporating pressure of the exchanger 4 is reduced. Thus, discharge refrigerant from a compressor 6 is condensed to be liquefied by a second heat exchanger 3, reduced under pressure by the valve 7, then sent to the exchanger 4 to reduce the evaporation pressure of the exchanger 2, thereby enhancing dehumidifying capacity of the exchanger 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a dehumidifying and heating function.

[0002]

2. Description of the Related Art For example, as shown in FIG. 3, an air conditioner of this type disclosed in Japanese Patent Application Laid-Open No. 4-151324 has one end of a first heat exchanger A arranged in an air conditioning duct. One end of the second heat exchanger B is connected through a parallel circuit of the solenoid valve C and the capillary tube D, and the other end of the second heat exchanger B is four-sided during dehumidification heating operation. Valve E
To the high pressure side of the compressor F via the first heat exchanger A
The other ends of the two are communicated with the low pressure side of the compressor F, respectively.

Further, in this publication, instead of connecting the other end of the first heat exchanger A to the low pressure side of the compressor F, a third heat placed outside the air conditioning duct is used during dehumidifying and heating operation. It is also disclosed to connect to the low pressure side of compressor F via exchanger G.

[0004]

However, in the above-mentioned technique, the heating amount and the dehumidifying amount cannot be independently changed during the dehumidifying and heating. For example, if the number of rotations of the compressor is increased to increase the dehumidification amount of the first heat exchanger, the heat radiation amount of the second heat exchanger also increases and the blowout temperature increases accordingly.
Therefore, when the outside air temperature is low and the second heat exchanger is below freezing eye temperature and there is a risk of freezing, the above-described configuration has no other choice but to reduce the rotation speed of the compressor. There was an inconvenience that it was forced to decrease. Further, in the former configuration, since the latent heat of dehumidification and the work of the compressor determine the heating amount, there is a drawback that the power consumption becomes relatively large.

Further, also in the latter configuration using the third heat exchanger, the heat absorption amount of the heat exchanger outside the duct is generally set to be large in order to improve the heating capacity in the heating mode. The evaporation temperature in the vessel is close to the outside temperature. Therefore, in the intermediate period, the dehumidifying capacity of the first heat exchanger cannot be expected so much. Of course, also in this case, if the number of rotations of the compressor is increased, the evaporation temperature is lowered and the dehumidifying capacity is improved, but as described above, the amount of heat radiated by the second heat exchanger is large and the heating capacity becomes excessive. .

Therefore, in the present invention, the above-mentioned drawbacks can be solved, the dehumidifying amount and the heating capacity can be controlled independently, the freezing of the heat exchanger can be prevented without lowering the heating capacity, and the intermediate period It is an object of the present invention to provide an air conditioner capable of dehumidifying effectively.

[0007]

The gist of the present invention is, therefore, that the first and second heat exchangers are arranged inside the air conditioning duct, and the third heat exchanger is arranged outside the air conditioning duct.
Dehumidifying and heating the second heat exchanger and the first heat exchanger, and connecting the second heat exchanger and the third heat exchanger through at least an expansion valve. During operation, the low pressure side of the compressor is connected to the first and third heat exchangers, and the high pressure side of the compressor is connected to the second heat exchanger to form a dehumidifying and heating cycle. The heat exchange efficiency control means for controlling the heat exchange efficiency of the third heat exchanger is provided.

[0008]

Therefore, during the dehumidifying and heating operation, the refrigerant discharged from the compressor enters the second heat exchanger and radiates heat (condensation and liquefaction), and is transferred to the first and third heat exchangers via the expansion valve. They enter and return to the compressor after absorbing heat (evaporating). In this process, if the heat exchange efficiency of the third heat exchanger is reduced by the heat exchange efficiency control means, the amount of heat absorbed by the third heat exchanger is reduced, so the evaporation pressure is reduced, and accordingly, the same compressor is used. The evaporating pressure of the first heat exchanger connected to the low-pressure side of the first heat exchanger also becomes low, and the dehumidifying capacity of the first heat exchanger can be increased separately from the heating capacity. Therefore, the above-mentioned subject can be achieved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an air conditioner according to the present invention. The air conditioner is mounted on, for example, an automobile, and has first and second heat exchangers 2 arranged in an air conditioning duct 1. 3 and a third heat exchanger 4 arranged outside the air conditioning duct 1.

An inside / outside air switching device is provided on the most upstream side of the air conditioning duct 1, and an inside air inlet and an outside air inlet are selectively opened by an intake door. The inside air or the outside air that can be selectively introduced into the air conditioning duct 1 is sucked by the rotation of the blower, sent to the first and second heat exchangers 2 and 3, where heat is exchanged there from a desired outlet. It is designed to be supplied to the passenger compartment. Further, in this embodiment, the first heat exchanger 2 is arranged on the upstream side of the second heat exchanger 3.

One end 3a of the second heat exchanger 3 and one end 4a of the third heat exchanger are respectively connected to the first and second ports (I, II) of the four-way valve 5 by pipes, and the four-way valve 5 is also connected. The third and fourth ports (III, IV) of the compressor 6 are connected to the discharge side A and the suction side B of the compressor 6, respectively, by the four-way valve 4, so that the discharge side A of the compressor 6 becomes the second side.
Of the compressor 6 and the suction side B of the compressor 6 are connected to the one end 4a of the third heat exchanger 4 (first connection state, indicated by a solid line). When the discharge side A is connected to the one end 4a of the third heat exchanger 4 and the suction side B of the compressor 6 is connected to the one end 3a of the second heat exchanger 3 (second connection state, broken line). (Shown by) and can be switched.

The other end 3b of the second heat exchanger 3 is pipe-connected to one end 7a of the electrically controlled expansion valve 7, and the other end 4b of the third heat exchanger 4 is electrically controlled expansion valve 7. Is connected to the other end 7b of the pipe.

The first heat exchanger 2 has its one end 2a.
Is always connected to the suction side B of the compressor 6 by a pipe, and the other end 2b is connected to the second side via the expansion valve 8 and the electromagnetic valve 9.
The heat exchanger 3 and the electrically controlled expansion valve 7 are connected by piping.

The on / off of the solenoid valve 9, the switching of the four-way valve 5, and the opening degree of the electrically controlled expansion valve 7 are controlled by control signals from the control unit 10. This control unit 10 is
Input circuit including D / D converter and multiplexer, RO
The output signal from the temperature detector 11 for detecting the temperature of the first heat exchanger 2 is a known one having an arithmetic processing circuit including M, RAM, CPU, etc., and an output circuit including a driving circuit, etc. Detection signals and setting signals necessary for air conditioning control are input, and these signals are processed according to a predetermined program.

Next, among the control operations by the control unit 10, a specific control operation example of the four-way valve 5, the solenoid valve 9, and the electric expansion valve 7 during the dehumidifying and heating operation is shown in FIG.
It will be described based on the flowchart shown in FIG.

First, in step 50, the control unit 10 determines whether or not there is a request to use the above system as dehumidifying and heating, and if it is determined that there is no request to use as dehumidifying and heating, the four-way valve. 5, the control of this flow chart is finished with the setting state of the solenoid valve 9 and the electric expansion valve 7 being maintained up to now, and the process proceeds to the next control.

On the other hand, if it is determined in step 50 that there is a request for use as dehumidifying and heating, the process proceeds to step 52 and the four-way valve 5 is brought into the first connection state (solid line in FIG. 1). Then, in the next step 54, it is determined based on the output from the temperature detector 11 whether or not the temperature of the first heat exchanger (HE) 2 is 0 ° C. or higher. This is because when the first heat exchanger is below the freezing limit temperature, when the refrigerant is supplied, the fins of the heat exchanger freeze and the dehumidifying action cannot be expected.
This is to prevent this.

Therefore, basically, the solenoid valve 9 is opened during the dehumidifying and heating operation (step 56), but when the temperature of the first heat exchanger becomes 0 ° C. or less, the solenoid valve 9 is opened.
Is closed to prevent freezing (step 58).

Then, in the next step 60, the opening degree of the electrically controlled expansion valve 7 is adjusted based on various factors such as outside air temperature and humidity to control the heat absorption amount of the third heat exchanger 4. For example, in the intermediate period, if the opening degree of the electrically controlled expansion valve 7 is increased, the heat absorption from the outside air by the third heat exchanger increases, and the evaporation temperature in the third heat exchanger 4 increases. Close to the outside temperature. During dehumidifying and heating, the first heat exchanger 2 and the third heat exchanger 4 are both connected to the suction side B of the compressor 6 and are in communication with each other, and the evaporation pressure of the first heat exchanger 2 is the third. Since it becomes equal to the evaporation pressure of the heat exchanger 4, the dehumidifying capacity of the first heat exchanger 2 becomes small. Therefore, during the intermediate period, the opening degree of the electrically controlled expansion valve 7 is reduced to the third
The heat exchange efficiency of the heat exchanger 4 is reduced to reduce heat absorption from the outside air, thereby lowering the evaporation pressure of the third heat exchanger.

However, in the intermediate period, the compressor 6
The refrigerant flowing out of the discharge side A enters the second heat exchanger 3 where heat is released (condensed and liquefied), is decompressed by the expansion valve 7, and is sent to the third heat exchanger 4. The refrigerant radiated by the second heat exchanger is decompressed by the expansion valve 8 when the solenoid valve 9 is open and supplied to the first heat exchanger 2. Since the third heat exchanger 4 absorbs less heat from the outside air, the pressure on the low pressure side is kept low, and the evaporation pressure of the first heat exchanger 2 becomes low accordingly. Therefore, in the first heat exchanger 2,
The dehumidifying ability can be enhanced without increasing the rotation speed of the compressor 6, and the air sent from the upstream of the air conditioning duct 1 is sufficiently moisture-removed by the first heat exchanger 2 and dried. In this state, it is heated by the second heat exchanger 3 and supplied into the vehicle interior.

In the above-mentioned embodiment, the opening degree of the electrically controlled expansion valve 7 is forcibly reduced as a means for deteriorating the heat exchange efficiency of the third heat exchanger 4. However, instead of this, Alternatively, or together with this, the rotation of the fan 12 facing the third heat exchanger 4 may be slowed or stopped. Also in this case, since the heat absorbing effect from the outside air is reduced, the pressure on the low pressure side is reduced, and the first heat exchanger 2
The evaporation pressure of is reduced and the dehumidifying ability can be enhanced.

[0023]

As described above, according to the present invention,
During the dehumidifying heating operation, the low pressure side of the compressor is connected to the first and third heat exchangers, and the high pressure side of the compressor is connected to the second heat exchanger to form a cycle for dehumidifying and heating. By controlling the heat exchange efficiency of the third heat exchanger by the exchange efficiency control means, the dehumidifying capacity of the first heat exchanger can be varied independently of the second heating capacity. It is possible to improve the dehumidifying ability in the intermediate period without reducing Further, since the dehumidifying ability can be adjusted independently, it is possible to prevent the first heat exchanger from freezing.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing an example of dehumidifying and heating control operation of a control unit in the air conditioner of FIG.

FIG. 3 is a configuration diagram showing a conventional air conditioner.

[Explanation of symbols]

 1 Air Conditioning Duct 2 First Heat Exchanger 3 Second Heat Exchanger 4 Third Heat Exchanger 5 Four-way Valve 6 Compressor 7,8 Expansion Valve 9 Electromagnetic Valve 10 Control Unit 12 Fan

Claims (1)

[Claims] 1. A first heat exchanger and a second heat exchanger arranged inside the air conditioning duct, and a third heat exchanger arranged outside the air conditioning duct, and the first heat exchanger and the second heat exchanger. Heat exchanger,
And the second heat exchanger and the third heat exchanger are connected via at least an expansion valve, the low pressure side of the compressor is connected to the first and third heat exchangers during dehumidification heating operation, and the compressor is And a second heat exchanger are connected to form a cycle for dehumidifying and heating, and heat exchange efficiency control means for controlling the heat exchange efficiency of the third heat exchanger is provided in the cycle. An air conditioner characterized by the above.