JPH0544676Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a heat pump type air conditioner in which a plurality of indoor units are connected to one outdoor unit.

(b) Conventional technology If the number of operating indoor units decreases during heating operation, the high pressure increases abnormally and a high pressure protection switch is activated, stopping heating operation. Attempts have been made to reduce the capacity of the compressor and to return a portion of the refrigerant discharged from the compressor to the suction side of the compressor.

(c) Problems that the invention aims to solve In the heat pump type air conditioner presented in the above publication, a part of the refrigerant discharged from the compressor was returned directly to the suction side of the compressor, so the high pressure discharged refrigerant gas was reduced to low pressure. The problem was that refrigerant noise was generated when the refrigerant gas merged with the suction refrigerant gas.

The present invention solves these problems and provides a heat pump air conditioner in which a hot gas bypass circuit for preventing high pressure rise is also used as a defrosting circuit for an outdoor heat exchanger during heating.

(d) Measures to solve the problem This proposal includes a hot gas bypass circuit that directly guides a portion of the discharge gas from the variable capacity compressor to the outdoor heat exchanger during heating operation. A valve is provided that opens when the heat exchanger is defrosted and when the number of indoor units in operation decreases, and the capacity of the variable capacity compressor is reduced when the number of indoor units in operation decreases.

(e) Effect When three indoor units are in heating operation, 1
When one or two indoor units are stopped by turning on the stop switch, the capacity of the variable capacity compressor is reduced, and the compressor whose capacity has been reduced is removed by opening the valve of the hot gas bypass circuit. A portion of the discharged gas is led directly to the suction side of this compressor through an outdoor heat exchanger.

(F) Embodiment Figure 1 is a refrigerant circuit diagram of the proposed heat pump air conditioner, in which 1 shows a variable capacity compressor 2 whose operating frequency is varied by an inverter, an outdoor heat exchanger 3, a four-way valve 4, and a pressure reducer. An outdoor fan 8 is equipped with a temperature-sensitive automatic temperature expansion valve 5, an accumulator 6, a hot gas bypass circuit 7 that guides a part of the discharge gas from the compressor 2 to an outdoor heat exchanger during heating operation, and an outdoor fan 8. Units 9a, 9b, 9c are indoor heat exchangers 10a, 10b, 10c and electric expansion valves 11a,
11b, 11c and indoor fans 12a, 12b, 1
This is an indoor unit with a built-in 2c.

The aforementioned hot gas bypass circuit 7 is connected at one end between the compressor 2 and the four-way valve 4, and at the other end between the temperature-sensitive automatic temperature expansion valve 5 and the outdoor heat exchanger 3.

Reference numeral 13 denotes a valve provided in the hot gas bypass circuit 7, which is set to open when defrosting the outdoor heat exchanger 3 during heating operation and when the number of indoor units 9a, 9b, and 9c in operation decreases. .

Next, the control operation of the heat pump type air conditioner will be explained based on the flowchart shown in FIG. When the three indoor units 9a, 9b, 9c heat the room simultaneously, the four-way valve 4 is set to the solid line state, the indoor and outdoor fans 12a, 12b, 12c, 8 are operated, and the electric expansion valves 11a, 11b, 11c is opened, and the refrigerant discharged from the compressor 2 flows through the four-way valve 4.
- Indoor heat exchanger 10a, 10b, 10c - Electric expansion valve 11a, 11b, 11c - Temperature-sensitive automatic temperature expansion valve 5 - Outdoor heat exchanger 3 - Four-way valve 4 - Return to compressor 2 via accumulator 6 and each indoor heat exchanger 10a, 10b, 10c serves as a condenser,
A heating cycle is formed in which the outdoor heat exchanger 3 acts as an evaporator, the electric expansion valves 11a, 11b, and 11c act as auxiliary pressure reducers, and the temperature-sensitive automatic temperature expansion valve 5 acts as a main pressure reducer. When the three compressors are operated simultaneously, the compressor 2 is operated at a maximum operating frequency of 105 Hz, which is determined according to the heating load of each indoor unit 9a, 9b, and 9c. For example, when the compressor 2 is operating at 100Hz and the customer turns on the stop switch and one indoor unit 9b, 9c stops, the frequency is 75Hz.
50Hz when the two indoor units 9c stop.
Then, the capacity of the compressor 2 decreases at a variable speed of 5 Hz/2 seconds, the indoor fans 12b, 12c of the indoor units 9b, 9c stop, and the electric expansion valves 11b, 11c close. At the same time, the bypass valve 13 is opened and the timer of this valve is turned on. In other words, this heat pump type air conditioner includes indoor units 9a, 9b, 9c.
Since it is equipped with a controller that reduces the capacity of the variable capacity compressor 2 when the number of units in operation decreases,
When the number of operating units is reduced, a part of the discharge gas of the compressor 2 whose capacity has been reduced flows through the hot gas bypass circuit 7, and the liquid gas mixture flows into the outdoor heat exchanger 3 from the temperature-sensitive automatic temperature expansion valve 5. Since it joins with the refrigerant and is sucked into the compressor 2 and the high pressure decreases, the high pressure does not rise abnormally. Moreover, a part of the bypassed discharge gas is caused by the pressure loss of the outdoor heat exchanger 3 compared to the outlet side of the outdoor heat exchanger 3 and the flow divider 14.
Since the refrigerant is merged at the inlet side of the outdoor heat exchanger 3, where the pressure of the refrigerant is high by the pressure drop caused by the refrigerant, no large refrigerant noise is generated at the time of this merge.

When the timer expires after two minutes, the bypass valve 13 is closed, and the indoor unit 9a is operated alone and the indoor units 9a and 9b are operated simultaneously under normal high pressure.

In addition, when one to three units are in heating operation, if the outdoor heat exchanger 3 becomes frosted due to a drop in outside temperature, the bypass valve 13 opens, and a part of the gas discharged from the compressor 2 passes through the hot gas bypass circuit 7 to the outside. A defrosting operation is performed with hot gas flowing into the heat exchanger 3.

In addition, in the above embodiment, the indoor units 9a,
The stopping of the heating operation in 9b and 9c is also applied when the room temperature control thermostat of each indoor unit is turned off and one of the indoor units is stopped, and the fan of this indoor unit is also stopped. Moreover, the compressor 2 can be applied even if its capacity does not change.

On the other hand, during cooling operation, the four-way valve 4 switches to the broken line state, compressor 2 - four-way valve 4 - outdoor heat exchanger 3 - temperature-sensitive automatic temperature expansion valve 5 - electric expansion valve 11a, 1
1b, 11c - indoor heat exchanger 10a, 10b, 1
0c - Four-way valve 4 - Accumulator 6 - Compressor 2
A cooling cycle is formed that circulates to During such cooling operation, the bypass valve 13 is always closed.

(g) Effects of the invention According to this invention, when the number of indoor units in operation decreases during heating operation, the capacity of the compressor is reduced, and a portion of the gas discharged from the compressor whose capacity has been reduced is transferred directly to the outside. By guiding the hot gas to the heat exchanger, it is possible to suppress the generation of refrigerant noise and prevent abnormal increases in high pressure.Furthermore, this hot gas bypass circuit can also be used as a hot gas defrosting circuit for the outdoor heat exchanger. , it is possible to simplify the refrigerant circuit and reduce structural costs.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a refrigerant circuit diagram of a heat pump air conditioner, and FIG. 2 is a flowchart showing the heating operation of the heat pump air conditioner. 1... Outdoor unit, 2... Compressor, 3... Outdoor heat exchanger, 4... Four-way valve, 7... Hot gas bypass circuit, 9a, 9b, 9c... Indoor unit, 10a, 10b, 10c... …indoor heat exchanger,
13... Valve.

Claims (1)

[Scope of utility model registration request] One outdoor unit with a built-in variable capacity compressor, an outdoor heat exchanger, a four-way valve, and a pressure reducer is connected to multiple indoor units with built-in indoor heat exchangers. In a heat pump type air conditioner in which an indoor unit is capable of heating and cooling operation, one end is connected between the compressor and the four-way valve, and the other end is connected between the pressure reducer and the outdoor heat exchanger, and the air conditioner is connected to the compressor and the four-way valve during the heating operation. A hot gas bypass circuit is provided to guide a portion of the discharge gas from the compressor to the outdoor heat exchanger, and this hot gas bypass circuit is equipped with a valve that opens when the outdoor heat exchanger is defrosted and when the number of operating indoor units is reduced. A heat pump type air conditioner characterized in that the heat pump type air conditioner is provided with a controller that lowers the capacity of the variable capacity compressor when the number of operating indoor units decreases.