JPH03213971A - Control device for air conditioner - Google Patents

Abstract

PURPOSE:To prevent a refrigerant piping and an indoor heat exchanger from being frozen by providing piping temperature detector means and freezing detector means in the indoor air conditioner. CONSTITUTION:In a control device for an air conditioner where a plurality of indoor air conditions B1, B2 are connected to one outdoor air conditioner A, the indoor air conditioner B1(or B2) in interruption or in air supply detects piping temperature by piping temperature detector means TH11 (or TH12) when the air conditioner A is in a cooling operation state and a compressor 1 is actuated. Further, when freezing detector means 41 (or 42) for judging a frozen state judges a frozen state, control means 31 (or 32) controls the degree of opening of a motor-driven expansion valve 21 (or 22) to an entirely closed state. Hereby, the piping of the interruption or air supply indoor air conditioner B1 (or B2) can be prevented from being frozen.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for an air conditioner equipped with an electric expansion valve that controls the flow rate of refrigerant.

BACKGROUND OF THE INVENTION A conventional air conditioner control device in which a plurality of indoor units are connected to one outdoor unit will be described with reference to the drawings.

Figure 3 shows the refrigerant piping system, where A is the outdoor unit, B1. B
2 is an indoor unit. The outdoor unit A includes a compressor 1, an inverter 1a that adjusts its capacity by making the frequency variable, a four-way valve 12 that switches the flow of refrigerant, an assumulator 3, and an outdoor heat exchanger 4 as main equipment. Indoor unit B1.
In B2, an indoor heat exchanger 6 is installed as a main device, and each of the main devices is connected to each other by a refrigerant pipe 8.

Fig. 4 is a control circuit configuration diagram, in which the outdoor unit A includes a compressor 1 and an inverter 1a that changes the operating frequency of the compressor 1 to adjust its capacity, and the indoor units B1 and B2 include a refrigerant Electric expansion valves 21 and 22 that control the flow rate, valve opening control means 31 and 32 that control the opening of the electric expansion valve to a fully closed state or a predetermined valve opening, and indoor unit fans 71 and 72,
There is a remote control switch 51.52 for setting the operating state, and the inverter 1a, valve opening degree control means 31, 32, and indoor unit fans 41, 42 are connected to the remote control switch 51.52.

Now, indoor unit B1. It is assumed that the indoor unit B2 is in the cooling operation state, and then the operation state of the indoor unit B2 is changed to the stopped state by the remote control switch 52. At this time, the electric expansion valve 22 of the indoor unit B2 is brought into a fully closed state by the valve opening control means 32. When this state is reached, the refrigerant circulates from the compressor 1 to the four-way valve 2 and the outdoor heat exchanger 4, passes through the electric expansion valve 21 of the indoor unit through the refrigerant piping 8, and is heat exchanged by the indoor heat exchanger 61. It returns to the compressor 1 from the valve 2 through the accumulator 3, and does not flow to the indoor unit B2.

Incidentally, as shown in this prior art example, an air conditioner is known that is equipped with an inno valve, a compression valve, and an electric expansion valve to perform capacity control. ).

Problems to be Solved by the Invention In an air conditioner in which multiple indoor units are connected to one outdoor unit, the operating status of each indoor unit varies between cooling, stopping, and blowing air. Ashi,
This tendency is especially true when there are a large number of indoor units. Even in such a case, if there is only one outdoor unit and the indoor unit is in operation, the compressor is operated. At this time, the electric expansion valve of the indoor unit that is stopped or blowing air is in the fully closed condition, but when the electric expansion valve is fully closed, the electric expansion valve may be changed in a timely manner, foreign objects may be caught, or malfunction may occur. In some cases, it may not be completely closed, and in that case, the indoor unit must be stopped and the refrigerant must be flowing through the indoor unit.In particular, if the indoor unit is stopped, the indoor unit fan will stop and heat exchange will not take place. If the outdoor unit is not cooled, there is a risk that the refrigerant pipes will freeze and form ice.

The present invention enables the compressor of the outdoor unit to stop and stop while in operation.
The purpose is to prevent the refrigerant pipes of the indoor unit for blowing air from freezing.

Means for Solving the Problem In order to solve this problem, the air conditioner control device of the present invention is equipped with a compressor and an innovative device that adjusts the capacity of the compressor by making the operating frequency of the compressor variable. Targeting indoor units that are equipped with an outdoor unit and an electric expansion valve that controls the flow rate of refrigerant, the system includes an electric expansion valve control means that controls the opening of the electric expansion valve to a fully closed state, and detects the pipe temperature of the indoor unit. It consists of a pipe temperature detection means that detects the temperature of the pipe, and a freeze detection means that determines the frozen state based on a signal from the pipe temperature detection means.

Effect With the above configuration, in the present invention, in the control device for an air conditioner in which a plurality of indoor units are connected to one outdoor unit, when the outdoor unit is in the cooling operation state and the compressor is not operating. When the indoor unit stops or blows air, the pipe temperature detection means detects the pipe temperature, and when the freeze detection means determines the freezing state, the electric expansion valve control means causes the electric expansion valve control means to dynamically expand the pipes. This is to control the opening degree of the valve to a fully closed state, thereby avoiding stopping or freezing of the piping of the indoor unit for blowing air.

Embodiment A control device for an air conditioner according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a control device for an air conditioner according to an embodiment of the present invention. FIG. 2 is a flowchart showing the control of this embodiment. The refrigerant piping system is the same as the conventional configuration shown in Figure 3.
Components in FIG. 1 that have the same circuit configuration as the conventional configuration in FIG. 3 are designated by the same reference numerals and detailed explanations will be omitted.

In FIG. 1, in addition to the conventional configuration, indoor unit B1. B
2 includes pipe temperature detection means TH11 and TH12 for detecting the state of the refrigerant pipe temperature, and freeze detection means 41 and 42 for determining the frozen state, and the pipe temperature detection means TH
11, THL 2 and freeze detection means 41, 42 are connected to valve opening control means 31, 32.

The operation of the air conditioner configured as described above will be explained below.

First, indoor unit B1. By operating the respective remote control switches 51 and 52 of indoor units B1. B2
It is assumed that the outdoor unit A is set to the cooling operation state, and that the outdoor unit A is in the cooling operation state. Next, it is assumed that the indoor unit B2 is stopped by operating the remote control switch 62 of the indoor unit B2 (FIG. 2, 5 top 1).

At this time, the outdoor unit A is in the cooling operation state, and the electric expansion valve 21 of the indoor unit B1 is opened at a predetermined valve opening degree (not fully closed)9, and the electric expansion valve 22 of the indoor unit B2 is opened. The valve opening degree control means 32 controls the valve opening to be in a fully closed state (FIG. 2, top 2).

At this time, it is assumed that the electric expansion valve 22 of the indoor unit B2 is not fully closed due to timely changes, foreign matter, malfunction, etc.

In the stopped indoor unit B2, the pipe temperature is detected by the pipe temperature detection means TH12, and the frozen state is constantly determined by the freeze detection means 42.

Now, the compressor 1 of the outdoor unit A is operating, and the refrigerant circulates from the compressor 1 to the four-way valve 2 and the outdoor heat exchanger 61, and passes through the refrigerant pipe 8 and the electric expansion valves 21 and 22 of the indoor unit. The heat is exchanged with the indoor heat exchangers 61 and 61, and returns to the compressor 1 through the four-way valve 2 and the accumulator 3.

At this time, refrigerant also flows through indoor unit B2, which is stopped.
Since the indoor unit fan 72 is stopped, the heat exchanger is not activated and the temperature of the indoor heat exchanger 62 drops and becomes frozen (second
Figure 5 top 3).

When it becomes frozen, the pipe temperature detection means TH of indoor unit B2
12 and the freeze detection means 42 determine that the electric expansion valve 22 is in a frozen state, and the valve opening degree control means 32 operates the electric expansion valve 22 again to bring it into a fully closed state (FIG. 2, top 4).

Even with this, if the pipe temperature detection means TH12 and the freeze detection means 42 of the indoor unit B2 detect a frozen state, the operation of the compressor 1 is stopped (FIG. 2, top 5).

In this way, the electric expansion valve control device for the air conditioner
- In an air conditioner in which multiple indoor units are connected to one outdoor unit, the outdoor unit is stopped during cooling operation, or the indoor unit for blowing air is in a frozen state based on a signal from the piping temperature detection means. When the freeze detecting means detects freezing and it is determined that a frozen state exists, the valve opening control means 32 operates the stain-operated expansion valve 22 to fully close it to prevent freezing.

Effects of the Invention As described above, the air conditioner control device of the present invention includes an outdoor unit that includes a compressor and an inverter that varies the operating frequency of the compressor to adjust its capacity, and that controls the flow rate of refrigerant. Electric expansion is aimed at air conditioners in which multiple indoor units are connected to one outdoor unit, each equipped with an electric expansion valve, and controls the opening of the electric expansion valve to a fully closed state. It consists of a valve control means, a pipe temperature detection means that detects the pipe temperature of the indoor unit, and a freeze detection means that determines the frozen state based on a signal from the pipe temperature detection means, and when the outdoor unit is in cooling operation, the compressor When the indoor unit is stopped or blowing air, the electric expansion valve is in the fully closed state, but when the electric expansion valve is fully closed, the electric expansion valve changes in a timely manner.
There may be cases where the fully closed state is not ensured due to foreign matter or malfunction, and in that case, refrigerant will flow even if the indoor unit is stopped or blowing air. The present invention detects freezing of the refrigerant piping even when the indoor unit is stopped or blows air by having a pipe temperature detection means and a freeze detection means in the indoor unit. Since it prevents freezing, water leakage and removal of ice due to ice formation from the heat exchanger of the indoor unit can be prevented, so its practical effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram of an air conditioner according to an embodiment of the present invention, FIG. A refrigerant piping diagram of the conditioner, FIG. 4 is a control circuit configuration diagram of a conventional air conditioner. A... Outdoor unit, B1, B2... Indoor unit, 1... Compressor, 1a... Inverter, 21, 22... Electric expansion valve, 31.32・
...Valve opening control means, THll. THL 2... Piping temperature detection means, 41, 42
...Freeze detection means.

Claims (1)

[Claims] An outdoor unit including a compressor, an inverter that varies the operating frequency of the compressor to adjust its capacity, an electric expansion valve that controls the flow rate of refrigerant, and an opening degree of the electric expansion valve. an indoor unit equipped with an electric expansion valve control means for controlling the temperature of the refrigerant pipe, a pipe temperature detection means for detecting the temperature of the refrigerant pipe, and a freeze detection means for determining whether the refrigerant pipe is frozen; In an air conditioner in which an indoor unit is connected, when the outdoor unit is operating the compressor and the indoor unit is stopped or blowing air, the pipe temperature detected by the pipe temperature detection means is detected by the freeze detection means. 1. A control device for an air conditioner, characterized in that when a temperature that is determined to be freezing is reached, an electric expansion valve of an indoor unit is greatly reduced in opening by an electric expansion valve control means to be in a fully closed state.