JPH05231321A - Operating method for heat pump - Google Patents

Abstract

PURPOSE:To prevent poor lubrication and seizing due to the lack of lubrication oil by forcibly make an inverter driven compressor run at a low frequency for a fixed time and then make it run at the required frequency again in the case where it run at a high frequency for the specified time or longer. CONSTITUTION:While heating operation is conducted, the high temperature and pressure gaseous refrigerant discharged from the inverter drive compressor 1 of an outdoor unit 22 flows into an oil separator 17 through a discharge pipe 14, for being separated from oil. The separated oil returns to a compressor 1 through an oil returning pipe 19 and the fixed throttle 20 attached to the returning pipe 19. In addition, the refrigerant gas flows into the utilization side heat exchanger 6 of an indoor unit 23 radiates heat to the air in the room becoming high pressure liquid refrigerant. The inverter 21 of a compressor 1 is controlled by a controller 25 based on the detection signal of a pressure sensor 27. In this case, after the compressor 1 continuously runs at a high frequency for a specified time or longer (Step (5) Yes), it is forcibly made to run at a low frequency for a fixed time [Steps (6) and (7)], and then, it runs at a required frequency (3) again.

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 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 arrow, the oil enters the oil separator 17 through the discharge pipe 14, and the oil contained in the refrigerant gas is separated therein. The separated oil returns to the compressor 1 via the oil return pipe 19 and the fixed throttle 20 interposed therein, and is stored in the inner bottom of the closed container 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 connecting gas pipe 4, and the pipe joint 5, and then the indoor unit 23.
Enters the use side heat exchanger 6 and radiates heat to indoor air to be condensed and liquefied to become a high-pressure liquid refrigerant. This liquid refrigerant is adiabatically expanded by being squeezed by the expansion mechanism 7 to become a low-pressure liquid gas two-phase refrigerant. This liquid gas two-phase refrigerant passes through the pipe joint 9, the inside / outside connecting liquid pipe 10, and the pipe joint 11, and then the outdoor unit 22.
Return to the heat source side heat exchanger 14 through the check valve 12,
Here, by absorbing heat from the outside air, it is evaporated and vaporized into a low-pressure gas refrigerant. And this gas refrigerant is a four-way valve 2,
Airtight container of compressor 1 through suction pipe 16 and 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, the four-way valve 2 as shown by the dashed arrow. Then, it becomes a high-pressure liquid refrigerant, and when it is throttled by the expansion mechanism 13, it becomes a low-pressure liquid gas two-phase refrigerant. And, this liquid gas two-phase refrigerant is a pipe joint 11, an inside / outside connecting liquid pipe 10,
The heat is absorbed by the utilization side heat exchanger 6 through the pipe joint 9 and the check valve 8 to evaporate and become a low-pressure gas refrigerant. This gas refrigerant returns to the compressor 1 via the pipe joint 5, the inside / outside connecting gas pipe 4, the pipe joint 3, the four-way valve 2, the suction pipe 16, and the accumulator 18.

A compressor 1A and a motor 1B are built in an airtight container 1C of the compressor 1, and 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 indicates the signal line 28.
Is input to the controller 24 through the controller 24, and 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, and
24 supplies the current of the determined required frequency to the motor 1B.

[0005]

In the above-described conventional air conditioner, when the inverter-driven compressor 1 is operated at a high frequency and a high speed under high load, the oil taken out from the compressor 1 with the refrigerant gas is removed. 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 closed container 1C gradually decreases, causing poor lubrication of the compressor 1 or a seizure accident based on it. There was a fear.

[0006]

The present invention has been invented to solve the above problems, and its gist is to provide an inverter-driven compressor and an oil contained in a refrigerant gas discharged from the inverter-driven compressor. An oil separator to separate the
In the operating method of the heat pump including the oil return pipe for returning the oil separated by the oil separator to the inverter-driven compressor through the fixed throttle, when the operation at the high frequency of the inverter-driven compressor continues for a predetermined time, A heat pump operating method is characterized in that the inverter-driven compressor is forcibly operated once at a low frequency for a certain period of time, and then returned to the operation at a required frequency.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENT A control flow chart of the present invention is shown in FIG. The refrigerant circuit is the same as the conventional one shown in FIG. When the operation of the air conditioner is started in step, the air conditioning load is detected by the sensor 27 in step. Then, in step, 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, the request frequency is a predetermined value, for example, it is determined whether 70H _Z above, in the case of not, but the compressor 1 is operated at the request frequency, in the case of Yea a predetermined time in step , For example,
You can see if 9 minutes have passed. When the predetermined time has elapsed, in step, the low frequency the compressor 1 is predetermined, for example, it is operated at 50H _Z. Next, in step, it is judged whether or not a fixed time, for example, one minute has passed. When the fixed time has passed, the process moves to step and the compressor 1 is operated at the required frequency.

[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 that flows out with the discharged refrigerant gas
Since the amount of oil returned through 19 is less, compressor 1
The amount of lubricating oil 1D in the closed container 1C increases. Thus, after the compressor 1 is operated at 70H _Z or 9 minutes, the compressor 1 50H
Since the amount of oil in the compressor 1 is recovered by operating for 1 minute at _Z , it is possible to return the compressor 1 to the operation at the required frequency thereafter.

[0009]

According to the present invention, when the operation of the inverter-driven compressor at a high frequency continues for a predetermined time, the inverter-driven compressor is forcibly operated at a low frequency for a certain period of time, and then the required frequency is applied. Since the operation is resumed by the above, it is possible to prevent inadequate lubrication of the compressor and seizure accident due to the decrease of the lubricating oil in the compressor.

[Brief description of drawings]

FIG. 1 is a flowchart showing an 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

Continued Front Page (72) Masahiko Sasaki Inventor Masahiko Sasaki 3-chome, Asahimachi, Nishibiwajima-cho, Nishikasugai-gun, Aichi Mitsubishi Heavy Industries, Ltd. Air Conditioning Factory

Claims (1)

[Claims] 1. An inverter-driven compressor, an oil separator for separating oil contained in refrigerant gas discharged therefrom, and oil returned by the oil separator to the inverter-driven compressor via a fixed throttle. In the method of operating a heat pump provided with an oil pipe, when the operation of the inverter-driven compressor at a high frequency continues for a predetermined time, once, the inverter-driven compressor is forcibly operated for a fixed time at a low frequency, and thereafter, A method for operating a heat pump, characterized by returning to operation at a required frequency.