JPH0754221B2 - Air conditioner - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner having a plurality of indoor units, particularly to defrosting operation during heating operation.

2. Description of the Related Art A conventional heat pump type air conditioner having a plurality of indoor units includes a compressor 2, a four-way valve 3, and an outdoor heat exchanger 4 installed in an outdoor unit 1, as shown in FIG. , Outdoor expansion valve 5
As a result, the indoor expansion valve 7 and the indoor heat exchanger 8 installed in the indoor unit 6 are connected in parallel and then sequentially connected in a ring to form a heat pump refrigeration cycle. Also compressor 2
An on-off valve 9 and a pressure reducer 10 are connected in series between the discharge pipe 2a and the suction pipe 2b. Further, the indoor side heat exchanger 8 and the outdoor side heat exchanger 4 are placed close to each other and the indoor side blower is provided.
11, outdoor blower 12 is installed. A plurality of (for example, three) indoor units 6a, 6b, 6c can be operated individually, and when operating only the indoor unit 6a, the other indoor units 6b, 6c are
The expansion valves 7b and 7c are fully closed and the indoor blowers 11b and 11c are also stopped. At this time, the compressor 2 is capacity-controlled by an inverter or the like, and is operated at a capacity according to the number of operating indoor units 6.

The outdoor side heat exchanger 4 during heating operation, especially when the outside temperature is low.
In this case, the refrigerant evaporation temperature also decreases, frost is formed on the surface of the outdoor heat exchanger 4, and the heat exchange capacity decreases, so that the heating capacity also decreases. Therefore, in order to perform the defrosting operation, the expansion valve 7 of the operating indoor unit 6 is fully opened, the refrigerant circulation amount is increased, and the defrosting is finished quickly, so that the capacity of the compressor 2 is maximized and the opening / closing valve is opened. By performing hot gas bypass by operating the indoor side blower 11, the indoor side blower 11 in operation is operated in a slight air flow, the outdoor expansion valve 5 is fully opened, and the outdoor blower 12 is stopped, so that the high temperature and high pressure refrigerant is supplied to the outdoor heat exchanger 4. Was supplied to perform defrosting.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional defrosting method, the pressure reducer 10 that bypasses between the discharge pipe 2a and the suction pipe 2b of the compressor 2 is used.
The hot gas bypass amount determined by is the optimum bypass amount with which the defrosting time is the shortest (see FIG. 5),
Unless the optimum bypass amount is selected according to the number of operating indoor units 6, the defrosting time changes significantly due to the change in the number of operating indoor units 6, and the heating capacity of the indoor unit 6 during the defrosting operation changes. Since it could not be obtained sufficiently, it had an effect on the room temperature drop during defrosting operation, which was a very big problem in terms of comfort.

The present invention solves the above-mentioned drawbacks of the prior art, and aims to improve the comfort at low outdoor temperature by always obtaining an optimum bypass amount even when the number of operating indoor units changes.

Means for Solving the Problems In order to achieve this object, the present invention makes it possible to arbitrarily change the bypass flow rate between the discharge pipe and the suction pipe of the compressor during the defrosting operation, such as an electric expansion valve. It is provided with a configuration in which it is changed by a flow rate control valve.

Effect The present invention is configured to defrost in the shortest defrost time by changing the bypass flow rate according to the number of operating indoor units and always obtaining the optimum bypass amount.

Example An example of the present invention will be described below with reference to the drawings. The same components as those of the conventional example will be denoted by the same reference numerals and detailed description thereof will be omitted.

Reference numeral 15 is a flow rate control valve, which can arbitrarily control the flow rate from the fully closed state and is connected so as to bypass between the discharge pipe 2a and the suction pipe 2b of the compressor 2.

During the heating operation, the defrosting operation is started when frost formation on the outdoor heat exchanger 4 progresses. At this time, the compressor 2 is increased to the maximum capacity by increasing the inverter frequency, etc., because the amount of heat supplied is increased due to an increase in the refrigerant circulation amount and an increase in the input. When the indoor unit 6 in operation, for example, the indoor unit 6a and the indoor unit 6b are operated and the indoor unit 6c is stopped, the expansion valves 7a and 7b are fully opened and the expansion valve 5 of the outdoor unit 1 is opened.
Similarly, fully open. At this time, the indoor blower 11a,
The air blower 11b is operated and the other blowers 11c and 12 are stopped. In addition, the flow rate control valve 15 is set to a valve opening degree according to the number of rolling units of the indoor unit 6, hot gas bypass is performed, the amount of refrigerant gas discharged from the compressor 2 is increased, and the dryness of the sucked refrigerant gas is increased.

At this time, even if the number of indoor units 6 that are in the heating operation changes, the shortest defrosting operation is always performed with an optimal bypass amount by changing the valve opening of the flow rate control valve 15 according to the number. It is possible and the defrosting operation performance is not affected.

EFFECTS OF THE INVENTION As is clear from the above embodiments, the air conditioner in the present invention connects the discharge pipe and the suction pipe of the compressor through a flow rate adjusting valve, and compresses during defrosting operation during heating operation. The capacity of the machine is maximized, the flow rate control valve is opened to the valve opening according to the number of operating indoor units, the expansion valve of the operating indoor unit is fully opened, the indoor blower is operated in a slight breeze, and the expansion valve of the outdoor unit. Fully open,
Since the outdoor blowers are stopped, the defrosting operation can always be performed in the shortest time even if the number of indoor operating units changes, and a stable heating capacity can be achieved, preventing the room temperature from dropping due to the prolonged defrosting operation. It has a great effect on comfortable air conditioning in a plurality of rooms.

[Brief description of drawings]

FIG. 1 is a refrigeration system diagram of an air conditioner according to an embodiment of the present invention, FIG. 2 is an operation diagram of each element of FIG. 1, and FIG. 3 is a heat pump type air conditioner having a plurality of conventional indoor units. Fig. 4 is a refrigeration system diagram of the machine, Fig. 4 is an operation diagram of each element of Fig. 3, and Fig. 5 is a characteristic diagram showing a relationship between a flow rate control valve and defrosting time. 1 ... outdoor unit, 2 ... compressor, 3 ... four-way valve, 4 ... outdoor heat exchanger, 5 ... outdoor expansion valve, 6a, 6b, 6c ... indoor unit, 7a, 7b, 7c …… Indoor expansion valve, 8a, 8b, 8c …… Indoor heat exchanger, 11a, 11b, 11c …… Indoor blower, 12 …… Outdoor blower, 15 …… Flow control valve.

Claims (1)

[Claims] 1. An outdoor unit provided with a compressor, a four-way valve, an outdoor heat exchanger, an outdoor blower, and an expansion valve, and a plurality of indoor units provided with an expansion valve, an indoor heat exchanger, and an indoor blower. The compressor is capable of increasing or decreasing its capacity depending on the number of operating indoor units, and the discharge pipe and the suction pipe of the compressor are connected through a flow rate adjusting valve to remove the capacity during heating operation. During frost operation, the capacity of the compressor is maximized, the flow rate adjusting valve is opened to a valve opening degree according to the number of operating indoor units, the expansion valve of the operating indoor unit is fully opened, and the indoor blower is set. An air conditioner characterized by light air operation, fully opening the expansion valve of the outdoor unit, fully opening the expansion valve of the outdoor unit, and stopping the outdoor blower.