JPH05106932A - Control system of multiple air-conditioner - Google Patents

Abstract

(57) [Summary] [Structure] When the number of indoor units during heating with a multi-type air conditioner decreases, bypass the discharge gas to the suction side and delay the stop of the blower of the stopped indoor unit to temporarily discharge gas pressure. After that, the capacity of the compressor is reduced and the opening degree of the expansion valve of the stopped indoor unit is reduced. [Effect] It contributes to the improvement of comfort of the air-conditioned space and the reliability of the refrigeration cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner, and more particularly to a control system for a multi-air conditioner.

[0002]

2. Description of the Related Art FIG. 2 shows a cycle system diagram. See also FIG.
Shows the control method of the prior art.

In the prior art, when the number of indoor units is changed, the blower for indoor units, the expansion valve for indoor units and the frequency of the compressor are changed in synchronization with the indoor unit operation button. There were the following four problems shown in 3.

(1) Abnormal increase in discharge pressure.

(2) Operation delay with respect to the frequency decreasing speed of the expansion valve for adjusting the cycle temperature.

(3) As a result of the expansion delay of the expansion valve due to the phenomenon of (2), the cycle temperature is lowered, and for this recovery, the suction pressure is decreased by throttling the expansion valve more than necessary thereafter.

(4) The temperature of blown air decreases due to the decrease in discharge pressure due to the phenomenon of (3).

Another conventional example is Japanese Patent Laid-Open No. 2-150.
No. 651 publication.

[0009]

DISCLOSURE OF THE INVENTION Problems to be solved by the above prior art are improved.

[0010]

The cause of the problem in the prior art is that a plurality of factors change rapidly at the same time, and the present invention shifts the change at the time of this transient phenomenon while gradually adjusting the state. is there.

[0011]

According to the present invention, the amount of change in the pressure and temperature of the cycle is reduced, and as a result, the temperature of the air blown out from the air conditioner can be stabilized, so that the comfort and the reliability of the refrigeration cycle are improved.

[0012]

FIG. 1 shows a control system when the number of indoor units is reduced according to the present invention, FIG. 2 shows a refrigeration cycle (prior art), and FIG. 3 shows its effect.

First, in the refrigeration cycle, as shown in FIG. 2, one outdoor unit is connected to three indoor units, and the outdoor unit is composed of two compressors, a variable frequency compressor 1 and a constant speed compressor 2. Four-way valve 3, Outdoor heat exchanger 4, Heating expansion valve 5,
A gas bypass valve is provided in the refrigeration cycle temperature control expansion valve 7 and a bypass circuit from the discharge gas pipe to the suction gas pipe. In addition, three indoor units have expansion valves 11 for cooling,
12, 13 and an indoor unit blower and an indoor unit heat exchanger are provided, respectively.

Next, the control when the number of indoor units during heating according to the present invention is reduced will be described with reference to FIG. From the top, the control operation of the indoor unit operation button, the indoor unit blower, the indoor unit expansion valve, the frequency variable compressor, the constant speed compressor, and the gas bypass valve is explained by taking the horizontal axis as the time axis.

At time t1, when two of the three indoor units in operation stop, the gas bypass valve opens the bypass circuit to prevent the discharge gas pressure from rising when the indoor blower stops. Next, at time t2, the blower for the indoor unit and the constant speed compressor are turned off, but the frequency variable compressor maintains the frequency at time t1 until time t3, and the waiting time t3 is for the heating expansion valve to decrease to the appropriate opening. The frequency is reduced from c to d in synchronization with the expansion valves 12 and 13 for indoor units closing from the opening a to the opening b. The gas bypass valve is turned off from a time t4 when the variable frequency compressor is lowered to the frequency d to a time t5 after a predetermined time.

By gradually changing the state when the number of operating indoor units decreases in this way, the changes in the discharge gas pressure and the suction gas pressure can be slowed down as shown in FIG. It is possible to stabilize the blown air temperature.

[0017]

According to the present invention, it is possible to prevent sudden changes in pressure and temperature in a multi-air conditioner and to stabilize the temperature of blown air, and to improve comfort in an air-conditioned space and reliability of a refrigeration cycle. .

[Brief description of drawings]

FIG. 1 is a timing chart showing a control method according to the present invention.

FIG. 2 is a refrigeration cycle system diagram.

FIG. 3 is an explanatory diagram showing an effect of the present invention.

FIG. 4 is a timing chart showing a control method according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Variable frequency compressor, 2 ... Constant speed compressor, 3 ... Four-way valve, 4 ... Outdoor unit heat exchanger, 5 ... Heating expansion valve, 6 ... Bypass valve, 7 ... Cycle temperature adjusting expansion valve, 8 Unit 1 indoor unit heat exchanger, 9 Unit 2 indoor unit heat exchanger, 10 Unit 3 indoor unit heat exchanger, 11 Unit 1 cooling expansion valve, 12
… Expansion valve for Unit 2 cooling, 13… Expansion valve for Unit 3 cooling.

Claims (1)

[Claims] 1. In a control system for a multi air conditioner in which a plurality of indoor units are connected to one outdoor unit, when the number of operating indoor units is reduced, the blower for indoor units is stopped when the indoor units are stopped. Delay and further synchronize with the stop of the indoor unit, put a bypass circuit from the discharge gas pipe to the suction gas pipe,
It also reduces the capacity of the compressor. After that, by cutting off the bypass circuit, a sudden change in pressure and temperature when the number of rooms is reduced is prevented, and a control system for a multi-air conditioner.