JP3225738B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner suitable for performing a cooling operation by promoting dehumidification while securing a large air flow.

[0002]

2. Description of the Related Art As described in Japanese Patent Application Laid-Open No. 63-73044, a conventional apparatus is designed to reduce the amount of air blown out of an air conditioner, that is, by reducing the amount of air passing through an evaporator of an air conditioner to dehumidify. It was for driving. The control method for fully closing or reducing the opening of the electric expansion valve is to control the electric expansion valve after confirming that the compressor has stopped, as in JP-A-4-93542. A method for preventing a problem such as an increase in the discharge pressure of a compressor is known.

[0003]

In an air conditioner or the like for cooling a computer, if a computer to be cooled is cooled by low-humidity air, the computer receives an obstacle such as static electricity. It is desirable not to dehumidify,
Dehumidification by increasing the volume of air passing through the evaporator and keeping the refrigerant evaporation temperature and pressure in the refrigeration cycle high to make the surface temperature of the heat exchange fins and pipes of the evaporator higher than the dew point temperature of the air drawn into the air conditioner I try not to.

However, dehumidification is required due to intrusion of high-humidity air into a computer room or increase in latent heat load by a person or the like, and an air conditioner corresponding to the dehumidification is required to have a dehumidification function. By the way, in such a case, if the conventional method is adopted, there is a problem that although the dehumidification can be performed, a sufficient air volume cannot be obtained.

An object of the present invention is to provide an air conditioner capable of holding a predetermined amount of blown air and dehumidifying by controlling a refrigeration cycle.

[0006] To achieve the above object, the present invention is an electric expansion valve is constituted by a plurality of parallel mutually, temperature and humidity cell for detecting the temperature and humidity of the intake air is cooled in the evaporator
A controller that reduces the opening of a part of the plurality of electric expansion valves when the humidity detected by the temperature and humidity sensor is higher than a predetermined value, and an opening value of the electric expansion valve. Calculating means for calculating the amount of refrigerant flowing through the electric expansion valve; and calculating the refrigerant flow to be reduced when the opening of a part of the plurality of electric expansion valves is reduced by the calculating means. An air conditioner, comprising: a controller that increases an opening value corresponding to a calculated refrigerant flow rate for a part of the expansion valve.

[0007]

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

In the air conditioner of the present invention, the high-temperature and high-pressure gas refrigerant discharged from the compressor is condensed by the condenser to become a high-temperature and high-pressure liquid refrigerant, decompressed by the electric expansion valve, and evaporated by the evaporator. As a result, a low-temperature and low-pressure gas refrigerant is formed, and a refrigeration cycle is formed that returns to the compressor via the accumulator. When the refrigerant evaporates, a predetermined flow rate of air that is cooled by exchanging heat with the refrigerant when the refrigerant evaporates is drawn in, and the cooled air is blown into the room for cooling.

The temperature / humidity sensor detects the temperature and humidity of the intake air cooled by the evaporator, and the controller detects a part of the plurality of electric expansion valves when the humidity detected by the temperature / humidity sensor is higher than a predetermined value . Since the opening degree is reduced , the refrigerant temperature and pressure in the evaporator decrease , the surface temperature of the finned pipe becomes lower than the dew point of the blown air, and dew condensation occurs on the fins and pipe surface. it can. Further, the calculating means calculates the refrigerant flow rate which is reduced according to the change in the opening degree of the electric expansion valve whose opening degree is reduced , and the controller controls the other electric expansion means.
By increasing the opening degree value corresponding to the refrigerant flow rate decreasing with respect to the valve , the change in the amount of refrigerant flowing from the electric expansion valve to the evaporator during the transition to the dehumidifying operation is suppressed, and excessive overheating of the refrigerant is prevented. Can be prevented.

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS.

(First Embodiment) FIG. 1 is a system diagram of a refrigeration cycle of an air conditioner according to a first embodiment, FIG. 2 is a pressure state diagram of the refrigeration cycle, and FIG. 3 is a graph showing expansion valve opening and refrigerant flow rate. FIG.

As shown in FIG. 1, in the air conditioner of the first embodiment, the main components of a compressor 1, a condenser 2, an electric expansion valve 3, 4, an evaporator 5, and an accumulator 6 are sequentially provided by refrigerant pipes. Connected to form a refrigeration cycle. And the compressor 1
A pressure sensor 7 for detecting the suction-side pressure, a pressure sensor 8 for detecting the discharge-side pressure, and a thermistor 9 for detecting the discharge-side refrigerant temperature are provided. Receiving the pressure detection signals from the pressure sensors 7 and 8 and the refrigerant discharge gas temperature from the thermistor 9,
A controller 10 for controlling the refrigeration cycle by a microcomputer is provided.

During the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is condensed in the condenser 2 to become a high-temperature and high-pressure liquid refrigerant, decompressed by the electric expansion valves 3 and 4, and decompressed by the evaporator 5. It evaporates into a low-temperature low-pressure gas refrigerant, and forms a refrigeration cycle returning to the compressor 1 via the accumulator 6.
When the refrigerant evaporates, a predetermined flow rate of air that is cooled by exchanging heat with the refrigerant is sucked into the evaporator 5, and the cooled air is blown into the room for cooling.

Normally, the controller 10
Is the compressor 1 according to the operating frequency determined by the cooling load.
And the refrigerant discharge side superheat degree TdSH, which is the difference between the refrigerant discharge gas temperature Td detected by the thermistor 9 and the condensation temperature Tc calculated from the refrigerant discharge pressure Pd detected by the pressure sensor 8, is set to an appropriate value in advance. The cooling operation is performed by adjusting the opening of the electric expansion valves 3 and 4 to V1 in FIG. 2 so as to have a value determined so that a refrigeration cycle can be formed. Further, the controller 10 is connected with a sensor 11 for detecting the temperature and humidity of the intake air of the air conditioner, that is, the intake air of the evaporator 5, and a sensor 12 for detecting the temperature and humidity of the blown air. The cooling load is calculated based on the above data.

As described above, in the normal cooling operation state in which the superheat degree TdSH on the refrigerant discharge side is controlled to a predetermined value, the humidity of the suction air detected by the sensor 11 is adjusted to a predetermined value set in the controller 10 in advance. When it becomes higher than the value, the controller 10 switches to a refrigeration cycle operation for promoting dehumidification (hereinafter referred to as a dehumidification promotion operation) in order to reduce the humidity.

The air conditioner of the present embodiment is provided with two electric expansion valves 3 and 4 in parallel as a pressure reducing device, and an evaporator 5 is divided corresponding to each electric expansion valve. When the dehumidification promotion operation is performed in the present embodiment, the controller 10 outputs an expansion valve opening V to one of the electric expansion valves 3 so as to bring the expansion valve opening V to a fully closed state.
A part of the evaporator 5 corresponding to the expansion valve 3 is closed. By the above operation, the heat exchange capacity in the evaporator 5 is reduced, and as a result, the refrigerant evaporation pressure and temperature are reduced, dew condensation in the evaporator 4 is promoted, and dehumidification can be performed from the intake air.

Here, during the transition to the dehumidification promotion operation, the refrigerant flow rate decreases and the refrigerant evaporation pressure decreases, so that the refrigerant is excessively heated and the refrigerant discharge side superheat degree TdSH increases. Therefore, in the controller 10, a program for previously calculating the relation value between the opening degree of the expansion valve and the flow rate in FIG. 3 is incorporated in the microcomputer, and the opening degree of the electric expansion valves 3 and 4 is Va and the electric expansion valve is set. When the valve 3 is fully closed, the opening of the electric expansion valve 4 is changed to an opening Vb at which the refrigerant flow rate doubles. Thus, a change in the refrigerant flow rate during a transition to the dehumidification promotion operation can be suppressed.

(Second Embodiment) In this embodiment, a refrigeration cycle having the same components as in the first embodiment is formed. The air conditioner of this embodiment is provided with two electric expansion valves 3 and 4 in parallel as a pressure reducing device, and an evaporator 5 corresponding to each electric expansion valve.
Has been split. When the dehumidification promotion operation is performed in the present embodiment, the controller 10 outputs to one of the electric expansion valves 3 such that the opening degree V of the expansion valve is reduced, and a part of the refrigerant in the evaporator 5 corresponding to the expansion valve 3. Decrease flow rate. By the above operation, the heat exchange capacity in the evaporator 5 is reduced, and as a result, the refrigerant evaporation pressure and temperature are reduced, dew condensation in the evaporator 5 is promoted, and dehumidification can be performed from the intake air.

Here, during the transition to the dehumidification promoting operation, the refrigerant flow rate decreases and the refrigerant evaporation pressure decreases, so that the refrigerant is excessively heated and the refrigerant discharge side superheat degree TdSH increases. Therefore, in the controller 10, a program for previously calculating the relation value between the opening degree of the expansion valve and the flow rate shown in FIG. 4 is incorporated in the microcomputer, and the opening degree of the electric expansion valves 3 and 4 is Va and the electric expansion valve is set. When 3 decreases the opening, the opening of the electric expansion valve 4 is changed to the opening value Vb. Thus, a change in the refrigerant flow rate during a transition to the dehumidification promotion operation can be suppressed.

(Third Embodiment) This embodiment forms a refrigeration cycle having the same components as the first embodiment. As shown in FIG. 5, the evaporator 5 is divided into upper and lower stages, an electric expansion valve 3 is provided at a lower part of the evaporator 5, and an electric expansion valve 4 is provided at an upper part. I have. Here, as described in the first embodiment, the opening of the expansion valve of the electric expansion valve is fully closed, and the lower part of the evaporator 5 corresponding to the expansion valve 3 is closed, so that the upper part of the evaporator 5 is closed. Is dehumidified by heat exchange. Then, the drain water dehumidified from the suction air at the upper portion and condensed on the fins and pipes of the heat exchanger and generated is dropped to the lower portion of the dry evaporator and eliminated, and the above operation is continuously performed. Thereby, dehumidification at the upper part of the evaporator is efficiently performed.

Here, during the transition to the dehumidification promotion operation, the flow rate of the refrigerant decreases, and the refrigerant evaporation pressure decreases, so that the refrigerant is excessively heated and the superheat degree TdSH on the refrigerant discharge side increases. Therefore, in the controller 10, a program for previously calculating the relation value between the opening degree of the expansion valve and the flow rate in FIG. 3 is incorporated in the microcomputer, and the opening degree of the electric expansion valves 3 and 4 is Va and the electric expansion valve is set. When the valve 3 is fully closed, the opening of the electric expansion valve 4 is changed to an opening Vb at which the refrigerant flow rate doubles. Thus, a change in the refrigerant flow rate during a transition to the dehumidification promotion operation can be suppressed.

(Fourth Embodiment) This embodiment forms a refrigeration cycle having the same components as the first embodiment. As shown in FIG. 5, the evaporator 5 is divided into upper and lower stages, an electric expansion valve 3 is provided at a lower part of the evaporator 5, and an electric expansion valve 4 is provided at an upper part. I have. Here, as described in the second embodiment, the opening degree of the expansion valve of the electric expansion valve 3 is reduced, and the flow rate of the refrigerant below the evaporator 5 corresponding to the expansion valve 3 is reduced. Dehumidification is performed by heat exchange at the upper part. Then, the drain water generated by dehumidifying the suction air at the upper portion and condensing on the fins and pipes of the heat exchanger and falling to the lower portion of the dry evaporator is eliminated, and the above operation is continuously performed. Thereby, dehumidification at the upper part of the evaporator is efficiently performed.

Here, during the transition to the dehumidification promoting operation, the flow rate of the refrigerant decreases and the refrigerant evaporation pressure decreases, so that the refrigerant is excessively heated and the superheat degree TdSH on the refrigerant discharge side increases. Therefore, in the controller 10, a program for previously calculating the relation value between the opening degree of the expansion valve and the flow rate shown in FIG. 4 is incorporated in the microcomputer, and the opening degree of the electric expansion valves 3 and 4 is Va and the electric expansion valve is set. When 3 decreases the opening, the opening of the electric expansion valve 4 is changed to the opening value Vb. Thus, a change in the refrigerant flow rate during a transition to the dehumidification promotion operation can be suppressed.

(Fifth Embodiment) In this embodiment, the operation of the refrigeration cycle in which the dehumidification is promoted as in the first to fourth embodiments is performed, and the humidity of the suction air detected by the sensor 11 is determined in advance. When it is set in the controller 10 and falls below a predetermined value,
The controller 10 stops the dehumidification promotion operation and returns the normal cooling operation.

Here, the electric expansion valve 3 having the fully closed or reduced opening degree in order to resume the cooling operation is replaced with the electric expansion valve 4.
When the refrigerant is returned to the opening degree, the refrigerant flow rate increases and the refrigerant evaporation pressure increases, so that the refrigerant may cause liquid compression in the compressor 1. Therefore, in the controller 10, a program for previously obtaining a relation value between the opening degree of the expansion valve and the flow rate shown in FIGS. 3 and 4 is incorporated in the micro computer, and the flow rate of the refrigerant in the electric expansion valve 4 is compared with the electric expansion valve 3. By calculating the opening degree value Va equally distributed to 4 and outputting it by the controller 10,
When returning to the cooling operation, a change in the refrigerant flow rate can be suppressed.

[0038]

According to the present invention, when the humidity of the intake air of the air conditioner rises to a certain value during the cooling operation of the air conditioner, the opening of the electric expansion valve is reduced during that time. Reduce the refrigerant evaporation temperature or refrigerant evaporator pressure,
Since the apparatus is controlled so that the surface temperature of the heat exchange finned pipe of the evaporator is lower than the dew point of the intake air, the dehumidification operation can be performed by controlling the cooling refrigeration cycle while maintaining a predetermined air volume. Therefore, by using the air-conditioning apparatus of the present invention, it is possible to supply a large amount of cold air to a computer at a required humidity and to alleviate the discomfort felt by a person in a computer room at a high humidity.
In addition, during the transition between the cooling operation and the dehumidification promotion operation, the flow rate of the refrigerant flowing from the electric expansion valve to the evaporator is adjusted, so that troubles such as excessive overheating of the refrigerant and liquid compression can be prevented.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle system diagram of an air conditioner of a first embodiment.

FIG. 2 is a refrigeration cycle pressure state diagram of the air conditioner of the first embodiment.

FIG. 3 is a characteristic diagram showing a relationship between an opening degree of an expansion valve and a flow rate of a refrigerant in the air conditioners of the first, third, and fifth embodiments.

FIG. 4 is a characteristic diagram showing a relationship between an expansion valve opening degree and a refrigerant flow rate of the air conditioners of the second, fourth, and fifth embodiments.

FIG. 5 is an explanatory view of an evaporator section of the air conditioner according to the third, fourth, and fifth embodiments.

[Explanation of symbols]

1 ... Compressor, 2 ... Condenser, 3,4 ... Electric expansion valve, 5 ...
Evaporator, 6 accumulator, 7, 8 pressure sensor, 9
... Thermistor, 10 ... Controller, 11, 12 ... Temperature and humidity sensor.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiromi Kawaguchi 390 Muramatsu, Shimizu-shi, Shizuoka Pref. Air Conditioning Systems Division, Hitachi, Ltd. (56) References JP-A-4-251147 (JP, A) JP-A-3-3 233251 (JP, A) Japanese Utility Model Hei 3-83750 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F24F 11/02 102

Claims (1)

(57) [Claims] An air conditioner for forming a cooling refrigeration cycle by sequentially circulating and connecting a compressor, a condenser, an electric expansion valve, an evaporator, and an accumulator by a refrigerant pipe, and for producing a predetermined amount of cool air from the evaporator. in the electric expansion valve is constituted by a plurality of parallel mutually, and temperature and humidity sensor for detecting the temperature and humidity of the intake air is cooled by the evaporator, the humidity detected by the temperature and humidity sensor is higher than a predetermined value sometimes, a calculating means for calculating the amount of refrigerant flowing through the electric expansion valve by opening value of the controller and the electric expansion valve to reduce the portion of the opening of the plurality of electric expansion valve, said plurality reducing the part of the opening of the stand of the electric expansion valve
A controller that, when reduced, calculates a decreasing refrigerant flow rate by the calculating means and increases an opening degree value corresponding to the calculated refrigerant flow rate for a part of the plurality of electric expansion valves. An air conditioner comprising: