JPH109644A - Air conditioner - Google Patents

Abstract

(57) [Summary] When the load on a computer or the like is extremely reduced, the indoor air temperature falls below the allowable range of adjustment of the auxiliary heat exchanger, and the compressor is stopped by thermo-off control. For this reason, the blown air temperature changes every time the compressor is turned on and off. A flow path in an evaporator is divided into two systems, and electronic expansion valves are connected to the two systems.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for cooling a computer or the like and controlling the temperature of blown air.

[0002]

2. Description of the Related Art In a computer or the like, air conditioning is performed by a "double floor air-conditioning system". desirable.

An air conditioner having a constant speed compressor in which the capacity cannot be controlled by an inverter is disclosed in JP-A-59-180253.
As described in Japanese Patent Application Laid-Open Publication No. H10-260, an auxiliary heat exchanger is provided, and when the temperature of the air blown out of the air conditioner falls below a control target value due to a decrease in load or the like, the refrigerant discharged from the compressor is branched and sent to the auxiliary heat exchanger. Then, the air cooled by the evaporator after being condensed is heated again to control the temperature of the blown air.

[0004]

However, in the prior art, the heat exchange capacity of the auxiliary heat exchanger is smaller than the heat exchange capacity of the evaporator, and the load is extremely reduced and the cooling capacity is larger than the load. In such a case, the temperature of the blown air decreases, so when the temperature falls below a certain predetermined indoor air temperature, the compressor is stopped by thermo-off control to adjust the blown air temperature. For this reason, the blow-off air temperature changes every time the compressor is turned on and off.
Alternatively, there has been a problem that it is not possible to quickly respond to a sudden increase in load while the compressor is stopped, or that reliability is reduced due to an increase in the number of times the compressor is turned on and off.

[0005] It is an object of the present invention to secure a constantly stable blow-off air temperature corresponding to a change in load by smooth capacity control.

[0006]

In order to achieve the above object, the present invention has two passages in an evaporator, an electronic expansion valve provided for each passage, and a temperature of the blown air which is determined by a control target value. If it continues for a certain period of time after the temperature drops below the value, one of the electronic expansion valves is fully closed, one of the flow paths in the evaporator is shut off, and the blown air temperature rises above the control target value by a predetermined value or more. After continuing for a predetermined time in this state, the electronic expansion valve was opened again, and the refrigerant was allowed to flow through the two channels of the evaporator flow path.

Further, when a pressure reducing device and an electromagnetic valve are provided, and one of the flow paths of the evaporator is shut off and the suction pressure of the compressor falls below an allowable lower limit, the electromagnetic valve is opened to discharge the compressor. A part of the refrigerant was returned to the suction side of the compressor through the decompression device, and when the suction pressure of the compressor rose to a value obtained by adding a predetermined value to the allowable lower limit, the solenoid valve was closed again.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1, 2, 3 and 4. Figure 1 shows the first
FIG. 2 is a system diagram of a refrigeration cycle of the second embodiment, FIG. 3 is a flowchart of control of the first embodiment, and FIG. 4 is a flowchart of control of the second embodiment. Is shown.

(First Embodiment) As shown in FIG. 1, the air conditioner of the present embodiment is of a remote condenser type and includes a compressor 1, a liquid receiver 7, electronic expansion valves 8 and 9, an evaporator, and an indoor unit. , Accumulator 11, auxiliary heat exchanger 12,
The outdoor unit is composed of main components of the condenser 4, the restriction valves 3 and 5, and is connected to each other by piping. Here, the evaporator 10 has two channels inside and is connected to the electronic expansion valve 8 or 9 respectively. The capacity of the auxiliary heat exchanger 12 is equal to or larger than the capacity of one system of the evaporator 10.

During the cooling operation, the refrigerant discharged from the compressor 1 is sent to the condenser 4 through the stop valves 2 and 3 and is sent to the condenser 4.
And 6, the evaporator 10 passes through the liquid receiver 7, the electronic expansion valves 8 and 9, and returns to the compressor 1 via the accumulator 11 to constitute a refrigeration cycle.

In addition, a part of the refrigerant discharged from the compressor 1 is sent to the auxiliary heat exchanger 12 to control the temperature of the blown air from the indoor unit, and is returned to the main refrigeration cycle via the flow control valve 13. Make up the heat cycle. The heat exchange capacity of the auxiliary heat exchanger 12 is adjusted by the flow control valve 13.

In this embodiment, the air conditioner performs the cooling operation by adjusting the electronic expansion valves 8 and 9 for cooling the computer and the like (FIG. 3: S2).

When the load generated by the computer or the like decreases, the refrigerant flows in the reheating cycle, and the air cooled by the evaporator 10 is heated again to adjust the temperature of the blown air (S2 in FIG. 3).

If the load further decreases and the temperature of the blown air falls below the control target value by a predetermined value beyond the allowable range of adjustment by the reheat cycle for a period of time T ₀ (FIG. 3: S3), the electronic expansion is performed. The valve 9 is fully closed (FIG. 3: S4)
One system of the flow path in the evaporator 10 is shut off, the heat exchange capacity of the evaporator 10 is reduced, the cooling capacity is reduced, and the temperature of the blown air is adjusted (FIG. 3: S5). When thereafter the outlet air temperature due to an increase in load is time T ₁ continues in a state of increased above a predetermined value than the control target value (Figure 3: S6), reopen the electronic expansion valve 9 (Fig. 3: S7), the blowout By controlling the air temperature (FIG. 3: S2), control is performed so as to keep the room air temperature at the control target value.

By configuring the above cycle, it is possible to eliminate the compressor thermo-off control at the time of a low load, and to secure a stable blown air temperature by the smooth displacement control.

(Second Embodiment) As shown in FIG. 2, the refrigeration cycle configuration of this embodiment is a configuration in which a decompression device 14 and a solenoid valve 15 are added to the refrigeration cycle configuration of the first embodiment.

In this embodiment, the air conditioner fully closes the electronic expansion valve 9 due to a decrease in load, etc., and performs cooling operation by one system of the flow path in the evaporator 10 and reheating operation by the auxiliary heat exchanger 12. (FIG. 4: S5).

In this embodiment, the electronic expansion valve 9 is fully closed and the capacity of the evaporator 10 is reduced, so that the pressure of the refrigerant that exits the evaporator 10 and returns to the compressor 1 via the accumulator 11 becomes equal to the suction pressure of the compressor 1. When the value falls below the allowable lower limit (FIG. 4: S
8), the solenoid valve 15 is opened (FIG. 4: S9), the pressure of a part of the high-pressure refrigerant discharged from the compressor 1 is adjusted by the decompression device 14, and the compressor 1 is passed through the solenoid valve 15 and the accumulator 11.
Return to Then, when the suction pressure of the compressor 1 rises by a predetermined value or more from the allowable lower limit, the solenoid valve 15 is closed again (FIG. 4: S12).

By performing the above control, it is possible to prevent the suction pressure of the compressor from dropping below the allowable lower limit.

[0020]

According to the present invention, it is possible to maintain a stable blown air temperature in response to a change in load quickly.

[Brief description of the drawings]

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

FIG. 2 is a system diagram of a refrigeration cycle of the air conditioner of the second embodiment.

FIG. 3 is a flowchart of control according to the first embodiment.

FIG. 4 is a flowchart of control according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2, 3, 5, 6 ... Restriction valve, 4 ... Condenser, 7
... Receiver, 8, 9 ... Electronic expansion valve, 10 ... Evaporator, 11 ...
Accumulator, 12: auxiliary heat exchanger, 13: flow control valve, 14: pressure reducing device, 15: solenoid valve.

Claims (1)

[Claims] An indoor unit comprising a compressor, an accumulator, a liquid receiver, an evaporator having two flow paths, and two electronic expansion valves corresponding to each flow path of the evaporator. An outdoor unit equipped with a condenser is connected by a refrigerant pipe to form a cooling refrigeration cycle, a predetermined amount of air is sent to the evaporator by a blower to perform a cooling operation, and one of the refrigerant discharged from the compressor is discharged. An auxiliary heat exchanger installed in the same air passage as the evaporator for reheating the air cooled by the evaporator by branching a section, and a flow control valve for adjusting the amount of refrigerant flowing through the auxiliary heat exchanger An air conditioner having a reheating operation function of controlling the temperature of the blown air, wherein the temperature of the air blown from the air conditioner by the cooling operation and the reheating operation is reduced by a predetermined value or more from a control target value for a predetermined time. If continued, the electronic expansion valve One of them was fully closed, and one of the flow paths of the evaporator was blocked to prevent a decrease in the temperature of the blown air by lowering the cooling capacity, and one of the flow paths of the evaporator was blocked. When the temperature of the air blown out by the cooling operation and the reheating operation has continued for a predetermined time in a state where the temperature has risen from the control target value by a predetermined value or more, the expansion valve that has been fully closed is reopened, and the evaporator has two flow paths and the cooling capacity. The air conditioner is characterized by maintaining the blown air temperature at a control target value by increasing the air temperature.