JP2930467B2 - Operation method of heat pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a heat pump such as an air conditioner, a refrigerator, a water heater and a dryer.

[0002]

2. Description of the Related Art An example of a conventional refrigerant circuit of an air conditioner is shown in FIG. Reference numeral 1 denotes an outdoor unit, which includes a constant capacity compressor 5, a variable capacity compressor 6 driven via an inverter, a four-way switching valve 7, an accumulator 8, an outdoor heat exchanger 12, and an outdoor blower 13. And so on.

[0003] 2A, 2B and 2C are indoor units, each of which includes an indoor heat exchanger 9A, 9B and 9C and an indoor blower 10A.
, 10B, 10C, and electronic expansion valves 11A, 11B, 11C, and the like. These indoor units 2A, 2B and 2C are connected in parallel to the indoor unit 1 via refrigerant pipes 3A and 3B, and the constant capacity compressor 5 and the variable capacity compressor 6 are connected in parallel in the refrigerant circuit. It is connected.

During the cooling operation of each of the indoor units 2A, 2B, and 2C, the gas refrigerant discharged from the constant capacity compressor 5 and the variable capacity compressor 6 merges and passes through the four-way switching valve 7 to generate outdoor heat. It enters the exchanger 12 and radiates heat to the outside air blown by the outdoor blower 13 to condense and liquefy. The liquid refrigerant flows into the indoor units 2A, 2B, and 2C in parallel via the refrigerant pipe 3A, and is adiabatically expanded by being throttled when flowing through the electronic expansion valves 11A, 11B, and 11C, thereby performing gas-liquid two-phase operation. Refrigerant. Next, the refrigerant enters the indoor heat exchangers 9A, 9B, 9C, where it evaporates and vaporizes by cooling the indoor air blown by the indoor blowers 10A, 10B, 10C. This gas refrigerant returns to the outdoor unit 1 via the refrigerant pipe 3B,
It branches via a four-way switching valve 7 and an accumulator 8, and is sucked into the constant displacement compressor 5 and the variable displacement compressor 6.

During the heating operation of each of the indoor units 2A, 2B, 2C, the four-way switching valve 7 is switched in the opposite manner as during the cooling operation. Thus, the refrigerant discharged from the fixed capacity compressor 5 and the variable capacity compressor 6 is supplied to the four-way switching valve 7, the refrigerant pipe 3B, the indoor heat exchangers 9A, 9B, 9C, the electronic expansion valves 11A, 11B, 11C,
The refrigerant returns to the compressors 5 and 6 through the refrigerant pipe 3A, the outdoor heat exchanger 12, the four-way switching valve 7, and the accumulator 8 in this order.

The flow rate of the refrigerant flowing through the indoor heat exchangers 9A, 9B, 9C is increased or decreased by adjusting the degree of opening of the electronic expansion valves 11A, 11B, 11C in accordance with the loads on the indoor units 2A, 2B, 2C. . When any one or two of the indoor units 2A, 2B, and 2C are stopped, the electronic expansion valve is fully closed.

As the amount of refrigerant circulating in the refrigerant circuit decreases, the capacity of the variable displacement compressor 6 is gradually reduced by reducing the frequency of the inverter as shown in FIG. At the same time as the compressor 5 is stopped, only the variable displacement compressor 6 is operated at the maximum capacity, and the capacity of the variable displacement compressor 6 is gradually reduced as the refrigerant circulation amount decreases.

[0008]

In the above conventional air conditioner, not only when a high pressure switch for detecting high pressure in the refrigerant circuit and a low pressure switch for detecting low pressure but also when an overcurrent flows to the inverter. Even when the inverter overheats, the power supply to the constant capacity compressor 5 and the variable capacity compressor 6 is interrupted to stop the air conditioner abnormally. Although there is no abnormality, there is a problem that the air conditioning feeling is significantly deteriorated due to the abnormal stop of the air conditioner.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is to provide a variable displacement compressor driven via a constant displacement compressor and an inverter. In a heat pump in which a compressor is connected in parallel in a refrigerant circuit, when an abnormality of any of the inverter, the variable displacement compressor and its drive motor is detected, power supply to the inverter is cut off and the constant displacement An operation method of a heat pump characterized by operating a type compressor.

[0010]

According to the present invention, when any of the inverter, the variable displacement compressor, and the drive motor thereof is detected, the power supply to the inverter is cut off and the constant displacement compressor is detected. To drive.

[0011]

FIG. 1 shows an example of an electric control circuit used for carrying out the method of the present invention. The refrigerant circuit is shown in FIG.
Is the same as the conventional one shown in FIG. A motor 20 for driving the constant capacity compressor 5 and an inverter 21 are connected in parallel to a commercial power supply 24 via magnet switches 22 and 23. The current whose frequency has been adjusted by the inverter 21 is
To the variable displacement compressor 6
Is driven. By increasing or decreasing the inverter frequency, the rotational speed of the motor 25 increases or decreases, and accordingly, the capacity of the variable displacement compressor 6, that is, the refrigerant discharge amount increases or decreases.

[0012] Constant displacement compressor 5, motor 20, inverter
21, the variable displacement compressor 6 and the motor 25 are provided with sensors 26, 27, 28, 29 and 30, respectively, for detecting the abnormality. When these sensors detect the abnormality, the output is sent to the controller 31. Is entered. High pressure switch 32 for detecting high pressure in the refrigerant circuit, low pressure switch 33 for detecting low pressure
In addition, outputs of sensors 34 and 35 for detecting an abnormality of the air conditioner are also input to the controller 31. The magnet switches 22 and 23 are opened and closed by instructions from the controller 31.

Thus, any abnormality of the inverter 21, the variable displacement compressor 6, and the motor 25 is detected by the sensors 28, 29, 30 and the other sensors 26, 27, 32, 33, 34, 35, etc. If no abnormality is detected, the controller 31 commands the magnet switch 23 to turn it off, and at the same time, commands the magnet switch 22 to turn it on. At this time, if the magnet switch 22 is on, it remains on. .

When an abnormality in the fixed displacement compressor 5 or the motor 20 is detected by the sensor 26 or 27 and no other sensors 28 to 35 detect an abnormality, the controller 31 commands the magnet switch 22 to turn it off. At the same time, a command is given to the magnet switch 23 to turn it on. At this time, if the magnet switch 23 is on, it remains on. Sensor 32 ~
When 35 or the like detects an abnormality, the controller 31 commands the magnet switches 22 and 23 to turn them OFF.
Although not shown, when any of the sensors 26 to 30 detects an abnormality, it is desirable to display the abnormality or generate an alarm.

When the power supply to the inverter 21 is cut off and the variable displacement compressor 6 is stopped while the constant displacement compressor 5 and the variable displacement compressor 6 are operating simultaneously, the capacity of the outdoor unit 1 is reduced. However, when the number of operating indoor units 2A, 2B, and 2C is small or when the load is small, the air-conditioning capacity decreases only slightly. When the operation of the compressor 5 is started, the air-conditioning capacity increases.

[0016]

According to the present invention, the power supply to the inverter is cut off when an abnormality is detected in any one of the inverter, the variable displacement compressor and the drive motor thereof. The motor can be prevented from being damaged. Then, since the power supply to the inverter is cut off and the constant displacement compressor is operated at the same time, the operation of the heat pump can be continued continuously.

[Brief description of the drawings]

FIG. 1 is an electrical control circuit diagram used for implementing the method of the present invention.

FIG. 2 is a refrigerant circuit diagram of a conventional air conditioner.

FIG. 3 is a diagram showing a relationship between a refrigerant circulation amount of an air conditioner and a capacity of a compressor.

[Explanation of symbols]

 5 Constant displacement compressor 21 Inverter 6 Variable displacement compressor 25 Motor 28, 29, 30 Abnormality detection sensor 22, 23 Magnet switch 24 Commercial power supply 31 Controller

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masahiko Sasakura 1-chome, Asahi-cho, Nishi-biwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Aircon Works (56) References JP-A-63-190563 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F24F 11/02 F25B 1/00

Claims (1)

(57) [Claims] 1. A heat pump in which a constant displacement compressor and a variable displacement compressor driven via an inverter are connected in parallel in a refrigerant circuit, wherein the inverter, the variable displacement compressor and the driving motor for the variable displacement compressor are connected. A method for operating a heat pump, characterized in that, when any abnormality is detected, the power supply to the inverter is cut off and the constant displacement compressor is operated at the same time.