JPH07120092A - Air conditioner - Google Patents

Abstract

PURPOSE:To enhance the heating power of a multi-room air conditioner having a plurality of indoor units by supplementing refrigerant stored in a refrigerant tank to the refrigerating cycle if the heating power is low when any one of the indoor units is operated to heat. CONSTITUTION:Refrigerant at the time of heating flows in the direction indicated by the arrows. An indoor unit 1 is connected to indoor units 2A, 2B through a branch circuit (refrigerant tube) having expansion valves 6a, 6b. When only the 2A is, for example, operated to heat, the refrigerant stays on the 2B side and hence the heating power of the 2A side might be lowered. In order to prevent a decrease in the heating power, a refrigerant tank 7 and a capillary tube 8 are provided in series between high and low pressure sides of the unit 1, and a heater 9 for heating the tank 7 provided. The heater 9 is turned on when a temperature difference obtained by temperature detecting means 11a, 11b becomes, for example, 5 deg.C or lower, thereby heating the tank 7. The refrigerant in the tank 7 becomes gaseous by the heating to flow through the tube 8, thereby supplementing refrigerant of a refrigerating cycle to make up for the insufficient power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to a structure of a refrigerating cycle of a multi air conditioner in which a plurality of indoor units are connected to one outdoor unit.

[0002]

2. Description of the Related Art In a multi-air conditioner in which a plurality of indoor units are connected to a single outdoor unit, the plurality of indoor units can be operated simultaneously or selectively. FIG. 2 shows an example of a refrigeration cycle of a multi-air conditioner. The high-temperature and high-pressure refrigerant discharged from the compressor 3 passes through the four-way valve 4 and then flows in the direction of the arrow during heating operation. The refrigerant to the machines 2A and 2B is branched in a diversion circuit, and the returning refrigerant is combined after passing through expansion valves (refrigerant flow rate control valves) 6a and 6b provided in the diversion circuit, and then from the outdoor heat exchanger 5. It returns to the compressor 3 via the four-way valve 4 again. By the way, in such an air conditioner, for example, the heating operation on the 2A side is continued,
When the 2B side is stopped, the refrigerant accumulates in the indoor heat exchanger 13b on the 2B side, and the refrigerant circulation amount of the refrigeration cycle becomes insufficient.
The heating capacity on the A side is reduced. Therefore, conventionally, the expansion valve 6b on the operation stop side is slightly opened to allow the refrigerant to flow, thereby preventing the refrigerant from staying.

[0003]

However, even in the air conditioner as described above, if the shunt circuit, that is, the refrigerant pipe between the outdoor unit and the indoor unit has a length of, for example, several tens of meters, the stagnation of the refrigerant is sufficiently caused. This cannot be prevented, and the heating capacity is reduced due to the lack of the refrigerant on the driving side, and in addition, a problem such as freezing of the outdoor heat exchanger occurs. Therefore, it is an object of the present invention to provide an air conditioner that does not cause such a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the refrigerant flow rate in each of the flow dividing circuits for branching and distributing the refrigerant discharged from the outdoor unit to a plurality of indoor units. In an air conditioner provided with an expansion valve capable of arbitrarily controlling the temperature and temperature detection means, a refrigerant tank and a capillary tube are provided in series between the inlet side and the outlet side of the diversion circuit, and the refrigerant tank is heated. The heater and the opening / closing means for opening / closing the power supply circuit of the heater are provided, and the refrigerant tank is heated when the temperature difference between the shunt circuits obtained from the detection value of the temperature detecting means is equal to or less than the set value.

[0005]

With the above structure, a part of the high temperature gaseous refrigerant flowing to the inlet side of the flow dividing circuit will flow into the refrigerant tank during the heating operation, but if the refrigerant flow rate in the refrigeration cycle is sufficient. For example, the temperature difference between the diversion circuits does not fall below the set value, and in such a state the refrigerant tank is not heated by the heater, so the high-temperature gaseous refrigerant flowing into the refrigerant tank is Heat is exchanged, and it becomes a liquid refrigerant and accumulates in the refrigerant tank.
If only one of the indoor units is heated and the refrigerant stays in the stopped indoor unit and the temperature difference between the shunt circuits falls below the set value, the heater heats the refrigerant tank. Therefore, the refrigerant that has been liquefied inside is evaporated, gasified and circulated through the capillary tube and circulated through the refrigeration cycle, so that the refrigerant shortage in the refrigeration cycle can be compensated.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows an example of a refrigeration cycle of a multi-air conditioner. Reference numeral 1 is an outdoor unit, and 2A and 2B are indoor units capable of operating either simultaneously or arbitrarily. The outdoor unit 1 includes a compressor 3, a four-way valve 4 that switches the flow of refrigerant, an outdoor heat exchanger 5, expansion valves (control valves for the refrigerant flow rate) 6a and 6b corresponding to the indoor units 2A and 2B, a refrigerant tank 7, a capillary. Tube 8, heater 9 for heating the refrigerant tank 7, relay 10 for opening and closing the power supply circuit of the heater 9, temperature detecting means (temperature sensor) 11a, 11b for detecting the temperature of the shunt circuit (refrigerant tube), outdoor unit control In addition to the section 12, an outdoor blower (not shown), an outdoor temperature detecting means, and the like are arranged. On the other hand, each of the indoor units 2A and 2B has an indoor heat exchanger.
In addition to 13a and 13b, an indoor blower (not shown), an indoor temperature detecting means, an indoor unit controller, etc. are arranged. These two indoor unit controllers and the outdoor unit controller 12 are connected by a signal line. ing.

By the way, the indoor units 2A and 2B can be operated simultaneously or arbitrarily, and the high-temperature and high-pressure refrigerant discharged from the compressor 3 during the heating operation passes through the four-way valve 4 and then in the direction of the arrow. And a part of it flows into the refrigerant tank 7. The refrigerant to the indoor units 2A, 2B is split in the split circuit and is heat-exchanged by the indoor heat exchangers 13a, 13b. Indoor unit 2
Refrigerants returning from A and 2B merge after passing through expansion valves 6a and 6b provided in the flow dividing circuit, and return from the outdoor heat exchanger 5 to the compressor 3 via the four-way valve 4 again. The refrigerant flowing into the refrigerant tank 7 is in a high-temperature gas state, but if the refrigerant flow rate of the refrigeration cycle is sufficient, the temperature difference between the flow dividing circuits will not fall below a set value (for example, 5 ° C.), Since the refrigerant tank 7 is not heated by the heater 9, the high temperature gaseous refrigerant that has flowed into the refrigerant tank 7 is heat-exchanged by the refrigerant tank 7 and becomes liquid refrigerant and accumulates in the refrigerant tank 7. Become.

If one of the indoor units 2A and 2B, for example, 2
When A is in the heating operation, if the refrigerant stays on the side of the indoor unit 2B that is stopped, the circulation amount of the refrigerant becomes insufficient, so that the heating capacity of the indoor unit 2A decreases and the temperature of the shunt circuit decreases. Also decreases. That is, it is possible to determine whether or not the circulation amount of the refrigerant is sufficient from the temperature of the shunt circuit. In this embodiment, the outdoor unit control unit 12 determines the temperature of the shunt circuit detected by the temperature detecting means 11a and 11b. The temperature difference between the diversion circuits is always calculated, and this temperature difference is set to the set value (5
(° C) or less, the relay 10 is turned on, and the heater 9 heats the refrigerant tank 7. When the refrigerant tank 7 is heated, the liquefied refrigerant evaporates and the gasified refrigerant returns from the capillary tube 8 to the outdoor heat exchanger 5 side, so that the refrigerant shortage in the refrigeration cycle is compensated. The capillary tube 8 is set so that a large amount of liquid refrigerant is stored in the refrigerant tank 7 during normal operation.

[0009]

In the air conditioner as described above, when only one of the indoor units is operated for heating,
If there is a case where the refrigerant accumulates on the other indoor unit side,
Since the refrigerant is replenished from the refrigerant tank, the heating capacity does not deteriorate, and the outdoor heat exchanger does not freeze due to insufficient refrigerant.

[Brief description of drawings]

FIG. 1 is a diagram showing a refrigeration cycle of a multi-air conditioner and a control system thereof according to an embodiment of the present invention.

FIG. 2 is a refrigeration cycle of a multi-air conditioner showing a conventional example and its control system diagram.

[Explanation of symbols]

 1 Outdoor unit 2A Indoor unit 2B Indoor unit 3 Compressor 4 Four-way valve 5 Outdoor heat exchanger 6a Expansion valve 6b Expansion valve 7 Refrigerant tank 8 Capillary tube 9 Heater 10 Relay 11a Temperature detection means (temperature sensor) 11b Temperature detection means (temperature) Sensor) 12 Outdoor unit controller 13a Indoor heat exchanger 13b Indoor heat exchanger

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F25B 5/02 A

Claims (3)

[Claims] 1. An air conditioner comprising an expansion valve capable of arbitrarily controlling a refrigerant flow rate and a temperature detecting means in each of the flow dividing circuits for branching and distributing the refrigerant discharged from an outdoor unit to a plurality of indoor units. , A refrigerant tank and a capillary tube are provided in series between the inlet side and the outlet side of the flow dividing circuit, a heater for heating the refrigerant tank, and an opening / closing means for opening and closing the power supply circuit of the heater are provided, and the temperature detection is performed. An air conditioner, wherein the refrigerant tank is heated when the temperature difference between the flow dividing circuits obtained from the detection value of the means is equal to or less than a set value. 2. The air conditioner according to claim 1, wherein one side of the refrigerant tank is connected to a high pressure side pipe during heating operation, and one side of the capillary tube is connected to an inlet side pipe of the outdoor heat exchanger. Machine. 3. The air conditioner according to claim 1, wherein the heater is turned on / off during heating operation.