CN102645057A - Oil return method of multi-connected air-conditioning unit during heating - Google Patents

Abstract

The invention discloses an oil return method for a multi-connected air conditioning unit during heating, which comprises the following steps: a. normally heating by the multi-connected air conditioning unit; b. adjusting the running frequency of the compressor (1) to be oil return frequency, adjusting the opening degree of the outer machine electronic expansion valve (2) to be outer machine oil return opening degree, adjusting the opening degrees of the inner machine electronic expansion valves (3) of all the inner machines to be inner machine oil return opening degree, and keeping the oil return frequency of the compressor (1), the outer machine oil return opening degree of the outer machine electronic expansion valves (2) and the inner machine oil return opening degree of the inner machine electronic expansion valves (3) to return oil for 2.5-3.5 minutes; c. adjusting the compressor (1) to the normal frequency and operating for 15-25 seconds; d. the opening degree of the external machine electronic expansion valve (2) is adjusted to be a normal opening degree, and the opening degrees of all the internal machine electronic expansion valves (3) are adjusted to be normal opening degrees. The oil return method can ensure good oil return effect, can not impact the compressor by liquid, and can continue to heat the indoor space in the oil return process.

Description

Oil return method of multi-connected air-conditioning unit during heating

technical field

The invention relates to a multi-connected air-conditioning unit, in particular to an oil return method for the multi-connected air-conditioning unit during heating.

Background technique

The multi-connected air conditioner unit in the prior art includes an outdoor unit, a plurality of indoor units connected in parallel, and two refrigerant circulation main pipes connecting each indoor unit and the outdoor unit.

Each outdoor unit includes a compressor, an oil separator, a four-way reversing valve, an outdoor heat exchanger (evaporator in heating mode), an electronic expansion valve for the outdoor unit, a liquid receiver, and a gas-liquid separator. The outlet of the compressor is connected with one end of the oil separator, the other end of the oil separator is connected with the first valve port of the four-way reversing valve, and the third valve port of the four-way reversing valve is connected with one of the two refrigerant circulation main pipes. The refrigerant pipes are connected, the other refrigerant pipe of the two main refrigerant circulation pipes is connected with one end of the electronic expansion valve of the external unit, the other end of the electronic expansion valve of the external unit is connected with one end of the outdoor heat exchanger, and the other end of the outdoor heat exchanger It communicates with the second valve port of the four-way reversing valve, the fourth valve port of the four-way reversing valve communicates with one end of the gas-liquid separator, and the other end of the gas-liquid separator communicates with the compressor inlet. In addition, each outdoor unit includes an outdoor fan that causes the outdoor heat exchanger to exchange heat with the outdoor environment. In the heating mode, the first valve port of the four-way reversing valve is connected to the third valve port, and the second valve port is connected to the fourth valve port, that is, the refrigerant flows along the compressor, indoor heat exchanger, outdoor heat exchanger, The route of the compressor circulates; in the cooling mode, the four-way reversing valve changes direction so that the first valve port communicates with the second valve port, and the third valve port communicates with the fourth valve port, that is, the refrigerant flows along the compressor, outdoor The route of heat exchanger, indoor heat exchanger and compressor circulates.

Each indoor unit includes an indoor unit electronic expansion valve and an indoor heat exchanger (condenser in heating mode). One end of the indoor heat exchanger is connected to one end of the indoor unit electronic expansion valve, and the other end of the indoor unit electronic expansion valve is connected to the One of the two refrigerant circulation main pipes is communicated, and the other end of the indoor heat exchanger is communicated with the other refrigerant pipe of the two refrigerant circulation main pipes. In addition, each indoor unit includes an indoor fan that causes the indoor heat exchanger to exchange heat with the indoor environment.

The electronic expansion valve of the external unit, the electronic expansion valve of the internal unit and the compressor are all electrically connected to the main controller of the air conditioner.

When the compressor is running, the lubricating oil that protects the compressor will leave the compressor and enter the pipeline along with the high-temperature and high-pressure gaseous refrigerant. Although the oil separator at the outlet of the compressor can slow down this situation, the long-term operation of the compressor will , there will still be more lubricating oil leaving the compressor and entering the pipeline, which requires the multi-connected air conditioner unit to return oil.

When the lubricating oil is at high pressure, the degree of mixing with the refrigerant is higher, and at low pressure, the lubricating oil is easy to separate from the refrigerant. In the heating mode, the refrigerant will be throttled and lowered by the electronic expansion valve of the external unit. In this way, the refrigerant will flow through the external unit The refrigerant pressure of the electronic expansion valve is reduced, and the lubricating oil is separated from the refrigerant and deposited in a large amount in the pipeline and the outdoor heat exchanger at the rear of the electronic expansion valve of the external unit.

The traditional oil return method in the heating mode is to change the direction of the four-way reversing valve, so that the multi-connected air conditioner is switched from the heating mode to the cooling mode, and at the same time, the indoor fan is turned off. The principle of the traditional oil return method is to make the high-temperature and high-pressure refrigerant flow through the outdoor heat exchanger and nearby pipelines, so that a large amount of lubricating oil deposited in this area is mixed and taken away by the high-temperature and high-pressure refrigerant, and finally returned to the outdoor heat exchanger through the indoor heat exchanger. into the compressor. There is an insurmountable disadvantage in the traditional oil return method, which is the opening of the indoor electronic expansion valve: if the opening is too small, the refrigerant will be throttled and reduced, causing the lubricating oil to separate from the refrigerant, which is not conducive to return. Oil; if the opening is too large, since the indoor heat exchanger hardly exchanges heat, a large amount of liquid refrigerant will liquid hit the compressor again. Moreover, during the oil return process, due to the cooling mode, the indoor heating cannot be continued, and the user cannot use the air conditioner for heating.

Contents of the invention

The technical problem to be solved by the present invention is to provide a multi-connected air conditioner unit that can ensure a good oil return effect without liquid hitting the compressor and can continue to heat the room during the oil return process. method.

The technical solution of the present invention is to provide a method for oil return during heating of a multi-connected air-conditioning unit, which includes the following steps:

a. The multi-connected air conditioner unit operates normally in the heating mode;

b. When oil return is required, the four-way reversing valve does not change direction, adjust the operating frequency of the compressor to the oil return frequency, and at the same time adjust the opening of the electronic expansion valve of the external unit to the oil return opening of the external unit, and at the same time set the The opening of the electronic expansion valve of the indoor unit of all indoor units is adjusted to the oil return opening of the indoor unit, and the multi-connected air conditioner unit maintains the oil return frequency of the compressor, the oil return opening of the electronic expansion valve of the outdoor unit, and the oil return opening of the internal unit. The oil return opening of the internal unit of the electronic expansion valve returns oil, and the oil return time is 2.5~3.5 minutes;

c. Adjust the operating frequency of the compressor back to the normal frequency, and run at the normal frequency for 15~25 seconds;

d. Adjust the opening of the electronic expansion valve of the external unit to the opening during normal operation, and at the same time adjust the opening of all electronic expansion valves of the internal unit to the opening during normal operation, and the oil return process is over.

The principle of this oil return method is: continue the heating cycle, the high-temperature and high-pressure gaseous refrigerant continues to exchange heat in the indoor heat exchanger, but the opening degrees of the electronic expansion valve of the internal unit and the electronic expansion valve of the external unit are both increased. In this way, The refrigerant is no longer throttling and lowering the pressure, so a large amount of lubricating oil accumulated in the outdoor heat exchanger and nearby pipelines will return to the compressor with the high-pressure refrigerant, that is, the oil return effect is ideal. Heat exchange evaporates liquid refrigerant, which can prevent excessive liquid refrigerant from hitting the compressor.

Using the above method, compared with the prior art, the oil return method of the multi-connected air conditioner unit of the present invention has the following advantages:

1. The indoor heat exchanger still continues to exchange heat. In this way, the multi-connected air conditioner unit continues to heat the room without lowering the room temperature, ensuring the customer's use effect; The valve opening is increased, and the refrigerant is no longer throttled and reduced. The high-pressure refrigerant can be fully mixed with the lubricating oil and brought back to the compressor, that is, the oil return effect is good. Moreover, the electronic components of the indoor unit that do not work before the oil return start The expansion valve is also opened, so that the high-temperature and high-pressure refrigerant gaseous refrigerant can directly pass through the indoor heat exchanger of these non-heat-exchanging indoor units and enter the outdoor heat exchanger in a gaseous state. This part of the refrigerant with higher temperature and higher pressure The mixing effect of the lubricating oil is better, and more lubricating oil can be brought back to the compressor, that is, the oil return effect is better; 3. The outdoor heat exchanger still continues to exchange heat, and the liquid refrigerant is evaporated into a gas refrigerant. In this way, Just avoid a large amount of liquid refrigerant liquid hitting the compressor.

As an improvement, the oil return frequency mentioned in step b refers to 45~55Hz. It has been proved by experiments that the oil return effect of the compressor at the frequency of 45~55Hz is ideal. Running at 45 Hz, there is no guarantee that the system will return oil completely.

As a further improvement, the oil return frequency is preferably 50Hz. Repeated tests have proved that the oil return of the compressor at 50Hz has the best effect, that is, there will be no high-pressure failure, and smooth and rapid oil return can be guaranteed.

As a further improvement, the oil return opening of the external machine described in step b refers to 470-480 steps. It has been proved by experiments that the opening of the electronic expansion valve of the external machine is 470-480 steps, and the oil return effect is better.

As a further improvement, the oil return opening of the external machine described in step b refers to 480 steps, and repeated tests have proved that when the opening of the electronic expansion valve of the external machine is 480 steps, the oil return effect is the best.

As a further improvement, the oil return opening of the internal machine described in step b refers to 470-480 steps. It has been proved by experiments that the opening of the electronic expansion valve of the internal machine is 470-480 steps, and the oil return effect is better.

As a further improvement, the oil return opening of the internal machine described in step b refers to 480 steps, and it has been proved through repeated tests that when the opening of the electronic expansion valve of the internal machine is 480 steps, the oil return effect is the best.

As a further improvement, the oil return time described in step b is 3 minutes. After repeated tests, it has been proved that this oil return time is the most ideal. If it exceeds 3 minutes, the system is prone to high pressure failure, which will cause an alarm to stop. If it is less than 3 minutes, it cannot Guaranteed full oil return.

As a further improvement, the compressor described in step c runs at the normal frequency for 20 seconds, so that after 20 seconds, each electronic expansion valve of the internal unit returns to the normal operating frequency, and there is a buffer time of 20 seconds, which can make the parallel connection The pressure of the indoor heat exchanger of each indoor unit is equalized.

Description of drawings

Fig. 1 is a schematic diagram of the system implementing the oil return method of the multi-connected air conditioner unit of the present invention during heating.

As shown in the figure 1. Compressor, 2. Electronic expansion valve of external unit, 3. Electronic expansion valve of internal unit. the

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the oil return method when the multi-connected air conditioner unit of the present invention is heating, it comprises the following steps:

a. The multi-connected air conditioner unit is running normally in the heating mode. At this time, the electronic expansion valve 2 of the external unit is the throttling device of the system, and the opening degree is generally about 120 steps. The indoor unit of the indoor unit that is turning on the heating The opening of the electronic expansion valve 3 is generally about 350 steps. The opening of the electronic expansion valve 3 of the indoor unit of the indoor unit that is not turned on and not heating is 0, and the frequency of the compressor 1 is adjusted according to the number of indoor units that are loaded. When the number of indoor units turned on is large, the operating frequency of compressor 1 is high, generally exceeding 50 Hz; when the number of indoor units turned on is small, the operating frequency of compressor 1 is small, generally lower than 50 Hz.

b. When oil return is required, the four-way reversing valve does not change direction, and continues to maintain the heating mode; adjust the operating frequency of compressor 1 to the oil return frequency, and the oil return frequency is 45~55Hz, preferably 50Hz; at the same time, the external unit The opening of the electronic expansion valve 2 is adjusted to the oil return opening of the external machine, and the oil return opening of the external machine is 470~480 steps, preferably 480 steps, that is, the opening of the electronic expansion valve 2 of the external machine is increased from about 120 steps to 480 steps. step. And at the same time, adjust the openings of the electronic expansion valves 3 of all indoor units to the oil return opening of the internal units. The oil return opening of the internal units is 470~480 steps, preferably 480 steps. The degree of opening of 3 is increased to 480 steps from about 350 steps or the degree of opening of the internal unit electronic expansion valve 3 that is not powered on is increased to 480 steps from 0. The multi-connected air conditioner unit maintains the oil return frequency of compressor 1, the oil return opening of the external unit electronic expansion valve 2, and the oil return opening of the internal unit electronic expansion valve 3. The oil return time is 2.5~ 3.5 minutes, preferably 3 minutes.

c. Adjust the operating frequency of compressor 1 back to the normal frequency, that is, adjust the operating frequency of compressor 1 from the oil return frequency of 50Hz back to the normal operating frequency before the oil return mode, and run at the normal frequency for 15~25 seconds, Preferably 20 seconds. the

d. Adjust the opening of the electronic expansion valve 2 of the external unit to the opening during normal operation, that is, adjust the opening of the electronic expansion valve 2 of the external unit back to about 120 steps. At the same time, adjust the openings of all the electronic expansion valves 3 of the indoor units to the openings during operation, that is, adjust the openings of the electronic expansion valves 3 of the indoor units that were opened back to about 350 steps or adjust the openings of the indoor units that were not opened The opening degree of the electronic expansion valve 3 of the internal unit is adjusted back to 0 steps. At this point, the oil return process is over, and the multi-connected air conditioner unit returns to normal heating mode operation.

Claims (9)

1. the oil return method a when VRF Air Conditioning System heats, it is characterized in that: it may further comprise the steps:

A, VRF Air Conditioning System be normal operation under heating mode;

B, when needing oil return; Four-way change-over valve does not commutate; The running frequency of compressor (1) is adjusted into the oil return frequency; Aperture with outer organic electronic expansion valve (2) is adjusted into outer machine oil return aperture simultaneously; And machine oil return aperture in simultaneously the aperture of the interior organic electronic expansion valve (3) of whole indoor sets being adjusted into, and VRF Air Conditioning System keeps the oil return frequency of compressor (1), the outer machine oil return aperture of outer organic electronic expansion valve (2), the interior machine oil return aperture oil return of interior organic electronic expansion valve (3), and the oil return time is 2.5 ~ 3.5 minutes;

C, the running frequency of compressor (1) is adjusted back normal frequency, and under normal frequency, move 15 ~ 25 seconds;

D, the aperture the when aperture of outer organic electronic expansion valve (2) is adjusted into normal operation, simultaneously will be all in the aperture of organic electronic expansion valves (3) aperture when being adjusted into normal operation, the oil return process finishes.

2. the oil return method when VRF Air Conditioning System according to claim 1 heats is characterized in that: the oil return frequency described in the step b is meant 45 ~ 55Hz.

3. the oil return method when VRF Air Conditioning System according to claim 2 heats is characterized in that: the preferred 50Hz of oil return frequency.

As claimed in claim 1, wherein the multi-type air conditioning unit heating the oil return, characterized in that: step b outside the machine described in the opening degree of the oil return means 470 to step 480.

5 according to claim 4, wherein the multi-type air conditioning unit heating the oil return, characterized in that: step b, said outer drive 480 is preferably an oil return opening step.

As claimed in claim 1, wherein the multi-type air conditioning units heating the oil return, characterized in that: in said step b inside the machine back to the oil opening is 470 to 480 steps.

As claimed in claim 6, wherein the multi-type air conditioning units heating the oil return, characterized in that: in said step b inside the machine back to the oil opening 480 is preferably step.

8. the oil return method when VRF Air Conditioning System according to claim 1 heats is characterized in that: the oil return time described in the step b is 3 minutes.

9. the oil return method when VRF Air Conditioning System according to claim 1 heats is characterized in that: the compressor described in the step c (1) moves 20 seconds under normal frequency.

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