JP3073303B2 - 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 dehumidifier, and a water heater.

[0002]

2. Description of the Related Art FIG. 2 shows a refrigerant circuit of a conventional air conditioner. During the heating operation, the high-temperature and high-pressure gas refrigerant discharged from the inverter-driven compressor 1 of the outdoor unit 22 is:
As indicated by the solid arrows, the oil enters the oil separator 17 via the discharge pipe 14, where the oil contained in the refrigerant gas is separated. The separated oil returns to the compressor 1 via the oil return pipe 19 and the fixed throttle 20 interposed therebetween, and is stored in the bottom of the closed vessel 1C. The refrigerant gas from which the oil has been separated passes through the four-way valve 2, the pipe joint 3, the inside / outside connection gas pipe 4, and the pipe joint 5, and passes through the indoor unit 23.
Enters the use-side heat exchanger 6 and radiates heat to room air to condense and liquefy to become a high-pressure liquid refrigerant. The liquid refrigerant is adiabatically expanded by being throttled by the expansion mechanism 7 to become a low-pressure liquid-gas two-phase refrigerant. This liquid-gas two-phase refrigerant passes through a pipe joint 9, an inside / outside connection liquid pipe 10, and a pipe joint 11, and connects to the outdoor unit 22.
To the heat source side heat exchanger 14 via the check valve 12,
Here, it absorbs heat from the outside air and evaporates to become a low-pressure gas refrigerant. And this gas refrigerant is a four-way valve 2,
The sealed container of the compressor 1 via the suction pipe 16 and the accumulator 18
Inhaled into 1C.

During the cooling operation, the gas refrigerant discharged from the compressor 1 is condensed by radiating heat in the heat source side heat exchanger 15 through the discharge pipe 14, the oil separator 17, and the four-way valve 2, as indicated by the dashed arrow. As a result, the refrigerant becomes a high-pressure liquid refrigerant, and becomes a low-pressure liquid-gas two-phase refrigerant by being throttled by the expansion mechanism 13. The liquid-gas two-phase refrigerant is connected to a pipe joint 11, an internal / external connection liquid pipe 10,
The heat is absorbed by the use-side heat exchanger 6 through the pipe joint 9 and the check valve 8 to evaporate into a low-pressure gas refrigerant. This gas refrigerant returns to the compressor 1 via the pipe joint 5, the internal / external connection gas pipe 4, the pipe joint 3, the four-way valve 2, the suction pipe 16, and the accumulator 18.

[0004] A compression mechanism 1A and a motor 1B are built in a closed container 1C of the compressor 1, and a lubricating oil 1D is stored at the bottom thereof. A current is supplied to the motor 1B from the power supply 26 via the inverter 21. The suction pressure of the refrigerant gas detected by the pressure sensor 27 provided in the suction pipe 16 is a signal line 28.
The controller 24 determines the required frequency of the inverter-driven compressor 1 according to the suction pressure, that is, the air-conditioning load. This required frequency is output to the inverter 24 via the signal line 25,
24 supplies a current of the determined required frequency to the motor 1B.

[0005]

In the conventional air conditioner described above, when the inverter-driven compressor 1 is operated at a high frequency at a high speed under a high load, the oil taken out of the compressor 1 along with the refrigerant gas is reduced. The amount is larger than the amount of oil returned from the oil separator 17 to the compressor 1 via the oil return pipe 19 and the fixed throttle 20. Therefore, if the high-speed operation of the compressor 1 continues for a long time, the oil level of the lubricating oil 1D stored in the bottom of the sealed container 1C gradually decreases, causing poor lubrication of the compressor 1 or a seizure accident based on this. There was a fear.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is that it is housed in a closed container and stored at the bottom thereof.
Compression mechanism lubricated by lubricating oil and driving this compression mechanism
Motor and the frequency of the current supplied to this motor
To change the rotation speed of the motor
Operate according to the required frequency corresponding to the load
An inverter driving compressor, the inverter driving compressor
Oil separator for separating oil contained in the refrigerant gas discharged from the machine, and oil separated by this oil separator
Oil return pipe back to the closed container bottom of the upper Symbol inverter compressor
In the method of operating a heat pump having a fixed restrictor interposed in the oil return pipe , the required frequency is determined in advance.
Inverter-driven compression with high frequency exceeding a predetermined value
When the operation of the machine continues a first predetermined time period predetermined, once forcibly its dense the inverter-driven compressor
The amount of oil flowing out of the closed container passes through the fixed throttle
Pre-determined to be less than the amount of oil returned to the vessel
Was operated by a second predetermined time period which is predetermined at a low frequency, thereafter, in the heat pump operating method, characterized in that to return to the operation by the request frequency.

[0007]

FIG. 1 shows a control flowchart of the present invention. The refrigerant circuit is the same as the conventional one shown in FIG. When the operation of the air conditioner is started in step (1), the air conditioning load is detected by the sensor 27 in step (2). Then, in step (3), the compressor 1 is the predetermined frequency range, for example, is operated at the requested frequency determined in response to the air-conditioning load within a 35~95H _Z. In step (4), the required frequency is a predetermined value, for example,
Whether 70H _Z or is determined, in the case of not the compressor 1
Is operated at the required frequency, but in that case , i.e. 70 Hz
If the frequency is higher than the above, it is determined in advance in step (5).
It is checked whether or not the first predetermined time, for example, nine minutes has elapsed. After the first predetermined time has elapsed, in step (6), the compressor 1 detects the oil flowing out of the closed container 1c.
The amount of oil returned to the closed container 1c through the fixed throttle 20
Low frequency predetermined to be less than the amount, for example, it is operated at 50H _Z. Then, previously in step (7)
It is determined whether or not a predetermined second predetermined time, for example, one minute has elapsed. When the second predetermined time has elapsed, the process proceeds to step (3) and the compressor 1 returns to the operation at the required frequency.
That attributed.

[0008] Thus, the lubricating oil 1D in the closed casing 1C of the compressor 1 by the compressor 1 is operated at more high frequency 70H _Z is decreased gradually, the compressor 1 is operated at 50H _Z And the amount of oil flowing out along with the discharged refrigerant gas
The amount of lubricating oil 1D in the closed container 1C of the compressor 1 increases because the amount of oil returned through the fixed throttle 19 and the fixed throttle 20 becomes smaller. Therefore, the operation was field 9 minutes compressor 1 at 70H _Z or
Expediently, the oil quantity in the compressor 1 by operating one minute compressor 1 at 50H _Z is restored, thereafter, it is possible to return the compressor 1 to the operation by the request frequency.

[0009]

According to the present invention, the required frequency is determined in advance.
Inverter driven by high frequency exceeding specified value
When operation of the compressor is continued first predetermined time set in advance, once forcibly its sealing an inverter-driven compressor
The amount of oil flowing out of the container passes through the fixed throttle
Predetermined to be less than the amount of oil returned
Driving at a low frequency for a second predetermined time ,
Thereafter, in order to return to the operation by the request frequency, Lee
It is possible to prevent poor lubrication of the compression mechanism and seizure accidents due to a decrease in lubricating oil in the closed container of the inverter drive compressor.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of the present invention.

FIG. 2 is a system diagram of a conventional air conditioner.

[Explanation of symbols]

 1 Inverter driven compressor 17 Oil separator 19 Oil return pipe 20 Fixed throttle 24 Controller 21 Inverter 27 Load sensor

Continuation of the front page (72) Inventor Masahiko Sasakura, 3-chome, Asahimachi, Nishibiwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Aircon Works (56) References JP-A-3-229979 (JP, A) SHIKAI 63-4385 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04B 39/02 F04B 49/10 331

Claims (1)

(57) [Claims] 1. A storage device built in a closed container and stored at a bottom portion thereof.
Compression mechanism lubricated by lubricating oil and this compression mechanism
And the frequency of the current supplied to this motor
By changing the number of rotations,
With the required frequency corresponding to the load
Inverter-driven compressor to be operated and this inverter drive
An oil separator for separating oil contained in the refrigerant gas discharged from the dynamic compressor, and oil return pipe for returning the oil separated by the oil separator in a sealed container the bottom of the upper Symbol inverter compressor, through this oil return pipe The method of operating a heat pump having a mounted fixed throttle, wherein the operation of the inverter-driven compressor at a high frequency where the required frequency exceeds a predetermined value is predetermined.
When continued first predetermined time, once the amount of oil flowing out forcefully the sealed container to the inverter-driven compressor is on
Less than the amount of oil returned into the closed container through the fixed throttle
Predetermined at a predetermined low frequency to be
A method for operating a heat pump, comprising: operating for a second predetermined time , and thereafter returning to operation at a required frequency.