阅读说明：本技术 一种多联机空调系统回油的控制方法 (Control method for oil return of multi-split air conditioning system ) 是由 王有欣 熊琼 于 2021-08-16 设计创作，主要内容包括：一种多联机空调系统回油的控制方法,控制方法包括有以下步骤：步骤S1,计算系统油吐出量L1；步骤S2,根据空调系统的运行状态,计算系统累计油吐出量L,然后,根据系统累计油吐出量L和压缩机回油量的大小关系；步骤S3,空调系统运行回油运转模式,将空调系统调节为制冷模式,调节压缩机运行频率以回油频率的最低频率运行,调节室外电子膨胀阀至第一预设开度,室内换热器的风机停止运转,根据空调系统在步骤S1中运行的模式,提高没有运作的室内机的室内电子膨胀阀的开度B1和正在运作送风模式的室内机的室内电子膨胀阀的开度B2,步骤S4,根据压缩机运行频率与最低允许回油频率的大小关系,调节回油运转模式的运行时间。(A control method for oil return of a multi-split air conditioning system comprises the following steps: step S1, calculating a system oil discharge amount L1; step S2, calculating the accumulated oil discharge L of the system according to the running state of the air conditioning system, and then calculating the magnitude relation between the accumulated oil discharge L of the system and the oil return amount of the compressor; and step S3, operating the air conditioning system in an oil return operation mode, adjusting the air conditioning system to a refrigeration mode, adjusting the operation frequency of the compressor to operate at the lowest frequency of the oil return frequency, adjusting the outdoor electronic expansion valve to a first preset opening degree, stopping the operation of the fan of the indoor heat exchanger, increasing the opening degree B1 of the indoor electronic expansion valve of the indoor unit which is not operated and the opening degree B2 of the indoor electronic expansion valve of the indoor unit which is operating in the air supply mode according to the operation mode of the air conditioning system in the step S1, and adjusting the operation time of the oil return operation mode according to the magnitude relation between the operation frequency of the compressor and the lowest allowed oil return frequency in the step S4.)

1. The control method for oil return of the multi-split air conditioning system is characterized by comprising the following steps of: the control method comprises the following steps:

step S1, the air conditioning system continuously detects the condensation temperature T3, the exhaust temperature T5, the compressor frequency, the compressor oil return amount and the compressor rotating speed, if the compressor rotating speed is detected to be less than or equal to the preset rotating speed, the primary system oil discharge amount L1 is calculated in each rated time according to the compressor frequency and the exhaust superheat correction coefficient; if the detected compressor rotating speed = the preset rotating speed, calculating a primary system oil discharge amount L1 according to the compressor frequency, the compressor rotating speed, the MAX rotating speed oil discharge amount and the exhaust superheat correction coefficient within each rated time; after the system oil discharge amount L1 is calculated, the operation goes to step S2;

step S2, calculating the accumulated oil discharge L of the system according to the operation state of the air conditioning system, and then judging whether to operate step S3 according to the magnitude relation between the accumulated oil discharge L of the system and the oil return amount of the compressor; if the air conditioning system is in a continuous operation state, the system cumulative oil discharge amount L = the system oil discharge amount L, and if the obtained system cumulative oil discharge amount L is not less than the compressor oil return amount, the step S3 is executed; if the air conditioning system is in a starting operation state, the system cumulative oil discharge amount L = last system cumulative oil discharge amount L2+ system oil discharge amount L1, and if the obtained system cumulative oil discharge amount L is more than or equal to the compressor oil return amount x 2, the step S3 is executed;

step S3, the air conditioning system runs an oil return operation mode, the air conditioning system is adjusted to a refrigeration mode, then the operation frequency of the compressor is adjusted to run at the lowest frequency of the oil return frequency, the outdoor electronic expansion valve is adjusted to a first preset opening degree, the fan of the indoor heat exchanger stops running, according to the running mode of the air conditioning system in the step S1, the opening degree B1 of the indoor electronic expansion valve of the indoor unit which is not running and the opening degree B2 of the indoor electronic expansion valve of the indoor unit which is running in the air supply mode are improved, and then the step S4 is run;

step S4, detecting the compressor running frequency, adjusting the running time of the oil return running mode according to the magnitude relation between the compressor running frequency and the lowest allowable oil return frequency, and running step S5 after finishing the oil return running mode;

and step S5, adjusting the opening degree B1 and the opening degree B2 to 0 step.

2. The method for controlling oil return of a multi-split air conditioning system according to claim 1, wherein: in step S4, if the compressor operation frequency is greater than or equal to the lowest allowable oil return frequency, the oil return operation mode is ended after the air conditioner operates the oil return operation mode for the first preset time; and if the operation frequency of the compressor is less than the lowest allowable oil return frequency, increasing the operation frequency of the compressor, enabling the air conditioning system to operate the oil return operation mode for a second preset time, and then ending the oil return operation mode.

3. The method for controlling oil return of the multi-split air conditioning system as claimed in claim 2, wherein: the first preset time is less than the second preset time.

4. The method for controlling oil return of a multi-split air conditioning system according to claim 1, wherein: in step S3, if the air conditioning system operates the cooling mode in step S1, adjusting the opening degree B1 and the opening degree B2 to a second preset opening degree; if the air conditioning system operates the heating mode in step S1, the opening degree B1 and the opening degree B2 are adjusted to a third preset opening degree.

5. The method for controlling oil return of the multi-split air conditioning system according to claim 4, wherein: the second preset opening degree is smaller than the third preset opening degree.

6. The method for controlling oil return of a multi-split air conditioning system according to claim 1, wherein: in step S1, an exhaust superheat correction coefficient is obtained from the size of HDSH = exhaust temperature T5 — condensation temperature T3.

7. The method for controlling oil return of a multi-split air conditioning system according to claim 6, wherein: if the HDSH is less than the first preset temperature, the exhaust superheat correction coefficient is a first preset coefficient; if the first preset temperature is less than or equal to HDSH and less than the second preset temperature, the exhaust superheat correction coefficient is a second preset coefficient; if the second preset temperature is less than or equal to HDSH and less than a third preset temperature, the exhaust superheat correction coefficient is a third preset coefficient; and if the third preset temperature is less than or equal to HDSH, the exhaust superheat correction coefficient is a fourth preset coefficient.

8. The method for controlling oil return of a multi-split air conditioning system according to claim 7, wherein: the first preset coefficient is smaller than the second preset coefficient and smaller than the third preset coefficient and smaller than the fourth preset coefficient.

9. The method for controlling oil return of a multi-split air conditioning system according to claim 1, wherein: if a shutdown signal is received in steps S3 and S4, the air conditioning system is shut down after completing step S4.

10. The method for controlling oil return of a multi-split air conditioning system according to claim 1, wherein: if the defrosting signal is received in the steps S3 and S4, the air conditioning system operates the defrosting mode first, calculates the accumulated oil discharge amount L of the system according to the steps S1 and S2 during the operation of the defrosting mode, and then the air conditioning system re-operates the step S3 after the defrosting mode is finished.

Technical Field

The invention relates to the technical field of air conditioner oil return control, in particular to a control method for oil return of a multi-split air conditioning system.

Background

Typically, after a period of operation, the air conditioning system enters an oil return mode of operation to recover the oil into the compressor. At present, the existing air conditioning system can fix the oil return operation time in the oil return operation mode, and such a control method may cause the compressor to run in an oil shortage state, further cause the increase of power consumption, heat productivity and component wear of the compressor, reduce the service life of the compressor, and even burn out the compressor. In addition, the existing air conditioning system runs in a refrigeration mode when running in an oil return operation mode, an indoor unit refrigerates, and if the air conditioning system runs in a heating mode before running in the oil return operation mode, the air conditioning system runs in the oil return operation mode, so that the outlet air temperature is reduced, and the indoor comfort is affected.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a control method for oil return of a multi-split air conditioning system.

In order to achieve the purpose, the invention provides a scheme of a control method for oil return of a multi-split air conditioning system, which comprises the following steps:

step S1, the air conditioning system continuously detects the condensation temperature T3, the exhaust temperature T5, the compressor frequency, the compressor oil return amount and the compressor rotating speed, if the compressor rotating speed is detected to be less than or equal to the preset rotating speed, the primary system oil discharge amount L1 is calculated in each rated time according to the compressor frequency and the exhaust superheat correction coefficient; if the detected compressor rotating speed = the preset rotating speed, calculating a primary system oil discharge amount L1 according to the compressor frequency, the compressor rotating speed, the MAX rotating speed oil discharge amount and the exhaust superheat correction coefficient within each rated time; after the system oil discharge amount L1 is calculated, the operation goes to step S2;

step S2, calculating the accumulated oil discharge L of the system according to the operation state of the air conditioning system, and then judging whether to operate step S3 according to the magnitude relation between the accumulated oil discharge L of the system and the oil return amount of the compressor; if the air conditioning system is in a continuous operation state, the system cumulative oil discharge amount L = the system oil discharge amount L, and if the obtained system cumulative oil discharge amount L is not less than the compressor oil return amount, the step S3 is executed; if the air conditioning system is in a starting operation state, the system cumulative oil discharge amount L = last system cumulative oil discharge amount L2+ system oil discharge amount L1, and if the obtained system cumulative oil discharge amount L is more than or equal to the compressor oil return amount x 2, the step S3 is executed;

step S3, the air conditioning system runs an oil return operation mode, the air conditioning system is adjusted to a refrigeration mode, then the operation frequency of the compressor is adjusted to run at the lowest frequency of the oil return frequency, the outdoor electronic expansion valve is adjusted to a first preset opening degree, the fan of the indoor heat exchanger stops running, according to the running mode of the air conditioning system in the step S1, the opening degree B1 of the indoor electronic expansion valve of the indoor unit which is not running and the opening degree B2 of the indoor electronic expansion valve of the indoor unit which is running in the air supply mode are improved, and then the step S4 is run;

step S4, detecting the compressor running frequency, adjusting the running time of the oil return running mode according to the magnitude relation between the compressor running frequency and the lowest allowable oil return frequency, and running step S5 after finishing the oil return running mode;

and step S5, adjusting the opening degree B1 and the opening degree B2 to 0 step.

Further, in step S4, if the compressor operation frequency is greater than or equal to the lowest allowable oil return frequency, the oil return operation mode is ended after the air conditioner operates the oil return operation mode for the first preset time; and if the operation frequency of the compressor is less than the lowest allowable oil return frequency, increasing the operation frequency of the compressor, enabling the air conditioning system to operate the oil return operation mode for a second preset time, and then ending the oil return operation mode.

Further, the first preset time is less than the second preset time.

Further, in step S3, if the air conditioning system operates the cooling mode in step S1, the opening degree B1 and the opening degree B2 are adjusted to a second preset opening degree; if the air conditioning system operates the heating mode in step S1, the opening degree B1 and the opening degree B2 are adjusted to a third preset opening degree.

Further, the second preset opening degree is smaller than the third preset opening degree.

Further, in step S1, an exhaust superheat correction coefficient is obtained from the size of HDSH, where HDSH = exhaust temperature T5 — condensation temperature T3.

Further, if the HDSH is less than a first preset temperature, the exhaust superheat correction coefficient is a first preset coefficient; if the first preset temperature is less than or equal to HDSH and less than the second preset temperature, the exhaust superheat correction coefficient is a second preset coefficient; if the second preset temperature is less than or equal to HDSH and less than a third preset temperature, the exhaust superheat correction coefficient is a third preset coefficient; and if the third preset temperature is less than or equal to HDSH, the exhaust superheat correction coefficient is a fourth preset coefficient.

Furthermore, the first preset coefficient is smaller than the second preset coefficient and smaller than the third preset coefficient and smaller than the fourth preset coefficient.

Further, if a shutdown signal is received in steps S3 and S4, the air conditioning system is shut down after completing step S4.

Further, if the defrosting signal is received in steps S3 and S4, the air conditioning system operates the defrosting mode first, and calculates the accumulated oil discharge amount L of the system according to steps S1 and S2 during the operation of the defrosting mode, and then the air conditioning system re-operates step S3 after the end of the defrosting mode.

The invention has the beneficial effects that: accurately controlling the air conditioning system to enter an oil return operation mode through the steps S1 and S2; by reducing the output and heat exchange of the refrigerant in the step S3, the oil discharge amount of the system is reduced, the air outlet temperature of the indoor unit is prevented from being lower in the oil return operation mode of the air conditioner, and the indoor comfort is improved; in step S3, the opening B1 and the opening B2 are increased to ensure smooth oil return of the indoor unit not in operation and the indoor unit in the air supply mode; the operation time of the oil return operation mode is controlled according to the actual situation through the step S4, and the oil shortage operation of the compressor is avoided; through the steps S1 to S5, the air conditioning system recovers the lubricating oil into the compressor in different operation modes on the premise of not influencing the comfort of a user, so that the lubricating oil in the compressor is sufficient, and the accurate control of the recovery of the lubricating oil is realized.

Drawings

Fig. 1 is a schematic diagram of a control method.

Fig. 2 is a schematic diagram of step S1.

Fig. 3 is a schematic diagram of step S2.

Fig. 4 is a schematic diagram of step S3.

Fig. 5 is a schematic diagram of step S4.

Detailed Description

To facilitate an understanding of the invention, the invention is described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete.

Referring to fig. 1, in the present embodiment, a method for controlling oil return of a multi-split air conditioning system includes the following steps:

step S1, the air conditioning system continuously detects the condensation temperature T3, the exhaust temperature T5, the compressor frequency, the compressor oil return quantity and the compressor rotation speed, if the detected compressor rotation speed is less than or equal to the preset rotation speed, the system oil discharge quantity L1 is calculated once in each rated time according to the compressor frequency and the exhaust superheat correction coefficient, wherein the system oil discharge quantity = (0.0002 compressor frequency-0.0025) = 15.8 × 10 the exhaust superheat correction coefficient = 0.5; if the detected compressor rotation speed = the preset rotation speed, the primary system oil discharge amount L1 is calculated for each rated time based on the compressor frequency, the compressor rotation speed, the MAX rotation speed oil discharge amount, and the discharge superheat correction coefficient.

In the present embodiment, in step S1, the rated time is 10S. The condensing temperature T3 is the temperature at the outlet of the outdoor side heat exchanger. The discharge temperature T5 is the temperature at the outlet of the compressor discharge pipe. The predetermined rotational speed is 50 Hz. The MAX rotation speed oil discharge amount was 1.35%. An exhaust superheat correction coefficient is obtained from the size of HDSH, where HDSH = exhaust temperature T5-condensation temperature T3, specifically,

if the HDSH is less than the first preset temperature, the exhaust superheat correction coefficient is a first preset coefficient;

if the first preset temperature is less than or equal to HDSH and less than the second preset temperature, the exhaust superheat correction coefficient is a second preset coefficient;

if the second preset temperature is less than or equal to HDSH and less than a third preset temperature, the exhaust superheat correction coefficient is a third preset coefficient;

and if the third preset temperature is less than or equal to HDSH, the exhaust superheat correction coefficient is a fourth preset coefficient.

In this embodiment, the first preset temperature is 5 ℃, the second preset temperature is 10 ℃, and the third preset temperature is 15 ℃; the first preset coefficient is 1.5, the second preset coefficient is 1.3, the third preset coefficient is 1.1, and the fourth preset coefficient is 1. Further, after the system oil discharge amount L1 is calculated, step S2 is executed.

Step S2, calculating the accumulated oil discharge quantity L of the system according to the operation state of the air conditioning system, and then judging whether to operate step S3 according to the magnitude relation between the accumulated oil discharge quantity L of the system and the oil return quantity of the compressor. If the air conditioning system is in a continuous operation state, the system cumulative oil discharge amount L = the system oil discharge amount L1, and if the obtained system cumulative oil discharge amount L is not less than the compressor oil return amount, the operation goes to step S3; if the air conditioning system is in the on operation state, the system cumulative oil discharge amount L = the last system cumulative oil discharge amount L2+ the system oil discharge amount L1, and if the obtained system cumulative oil discharge amount L is not less than the compressor oil return amount x 2, step S3 is performed. If the air conditioning system is first turned on, the last accumulated oil discharge amount L2 is 0. In the present embodiment, the previous system integrated oil discharge amount L2 is the system integrated oil discharge amount L calculated before the air conditioning system was shut down last time.

And step S3, the air conditioning system operates an oil return operation mode, the air conditioning system is adjusted to a refrigeration mode, then the operation frequency of the compressor is adjusted to operate at the lowest frequency of the oil return frequency and various protection frequency limiting frequencies to reduce the output of the refrigerant, the outdoor electronic expansion valve is adjusted to a first preset opening degree, the fan of the indoor heat exchanger is stopped to reduce the heat exchange of the refrigerant, and the opening degree B1 of the indoor electronic expansion valve of the indoor unit which is not operated and the opening degree B2 of the indoor electronic expansion valve of the indoor unit which is operating in the air supply mode are adjusted according to the operation mode of the air conditioning system in the step S1. Specifically, if the air conditioning system operates the cooling mode in step S1, the opening degree B1 and the opening degree B2 are increased to a second preset opening degree; if the air conditioning system operates the heating mode in step S1, the opening degree B1 and the opening degree B2 are increased to a third preset opening degree. Step S4 is executed after all adjustments in step S3 are completed. In this embodiment, the first preset opening is 380 steps, the second preset opening is 304 steps, and the third preset opening is 480 steps.

Step S4, detecting the running frequency of the compressor, adjusting the running time of the oil return running mode according to the magnitude relation between the running frequency of the compressor and the lowest allowable oil return frequency, specifically, if the running frequency of the compressor is more than or equal to the lowest allowable oil return frequency, ending the oil return running mode after the air conditioner runs in the oil return running mode for a first preset time, and enabling the accumulated oil discharge L accumulated value of the system to be 0; and if the operation frequency of the compressor is less than the lowest allowable oil return frequency, increasing the operation frequency of the compressor to the maximum value of the current operation frequency, enabling the air conditioning system to be in the oil return operation mode for a second preset time, and ending the oil return operation mode to reduce the accumulated oil discharge L of the system to 2/5 times, wherein the accumulated oil discharge L of the system is obtained through calculation in the step S2. After the oil return operation mode is ended, step S5 is executed.

And step S5, adjusting the opening degree B1 and the opening degree B2 to 0, so that the refrigerant and the oil do not flow to the indoor unit which is not operated and the indoor unit which runs the air supply mode.

In the present embodiment, if the shutdown signal is received in steps S3 and S4, the air conditioning system is shut down after step S4 is completed, so as to avoid the compressor from being starved of oil after the air conditioner is shut down.

In the present embodiment, if the defrosting signal is received in steps S3 and S4, the air conditioning system operates the defrosting mode first, and calculates the system accumulated oil discharge amount L according to steps S1 and S2 in the defrosting mode, and then the air conditioner re-operates step S3 after the end of the defrosting mode. By preferentially defrosting when defrosting is needed, the condition that the air conditioner frosts in the oil return process and the oil return is influenced is avoided.

In this embodiment, through steps S1 to S5 in the control method, the air conditioning system returns the lubricating oil to the compressor in different operation modes on the premise of not affecting the comfort of the user, so as to ensure the sufficiency of the lubricating oil in the compressor, and further, the accurate control of the lubricating oil recovery is realized, and the satisfaction of the operation conditions of the compressor components is ensured, so that the reliability and stability of the system operation are improved.

The above-described embodiments are merely preferred embodiments of the present invention, which is not intended to limit the present invention in any way. Those skilled in the art can make many changes, modifications, and equivalents to the embodiments of the invention without departing from the scope of the invention as set forth in the claims below. Therefore, equivalent changes made according to the spirit of the present invention should be covered within the protection scope of the present invention without departing from the contents of the technical scheme of the present invention.