阅读说明：本技术 空调系统的冷冻机油循环量控制方法 (Refrigerating machine oil circulation amount control method of air conditioning system ) 是由 崔俊 徐佳佳 罗荣邦 于 2020-04-14 设计创作，主要内容包括：本发明涉及空调技术领域,具体涉及一种空调系统的冷冻机油循环量控制方法。本发明旨在解决现有转子式压缩机在启动时容易出现串气的问题。为此目的,本发明的冷却机油循环量控制方法包括：在转子式压缩机启动后,检测转子式压缩机的实际排气温度；比较实际排气温度与转子式压缩机的目标排气温度的大小；在实际排气温度小于目标排气温度时,控制第二节流元件由初始开度增大至目标开度。本申请的控制方法能够通过在转子式压缩机启动时增大回油量的方式提高压缩机中的油膜厚度,保证压缩机启动过程中高压区与低压区之间的密封效果,避免压缩机串气情况的出现。(The invention relates to the technical field of air conditioners, in particular to a method for controlling the circulation volume of refrigerating machine oil of an air conditioning system. The invention aims to solve the problem that the prior rotor compressor is easy to generate air leakage when being started. To this end, the cooling oil circulation amount control method of the present invention includes: detecting the actual exhaust temperature of the rotor type compressor after the rotor type compressor is started; comparing the actual exhaust temperature with the target exhaust temperature of the rotor compressor; and when the actual exhaust temperature is lower than the target exhaust temperature, controlling the second throttling element to increase from the initial opening degree to the target opening degree. The control method can improve the thickness of an oil film in the compressor in a mode of increasing the oil return amount when the rotor type compressor is started, guarantee the sealing effect between a high-pressure area and a low-pressure area in the starting process of the compressor, and avoid the occurrence of the gas leakage condition of the compressor.)

1. A refrigerating machine oil circulation amount control method of an air conditioning system is characterized in that the air conditioning system comprises a rotor type compressor, an outdoor heat exchanger, a first throttling element, an indoor heat exchanger and an oil controller, the oil controller comprises a shell, an inlet pipe, an outlet pipe and an oil return pipe, the inlet pipe, the outlet pipe and the oil return pipe are arranged on the shell, the oil return pipe is communicated with an air suction port of the rotor type compressor, a second throttling element is arranged between the oil return pipe and the air suction port,

the control method comprises the following steps:

detecting the actual exhaust temperature of the rotor type compressor after the rotor type compressor is started;

comparing the actual exhaust temperature with a target exhaust temperature of the rotary compressor;

when the actual exhaust temperature is lower than the target exhaust temperature, controlling the second throttling element to increase from an initial opening degree to a target opening degree;

wherein the target opening degree is determined based on the initial opening degree, the actual exhaust temperature, and the target exhaust temperature.

2. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 1, characterized in that the target opening degree of the second throttling element is calculated using the following formula:

B＝B₀×[1+(P_m-P_s)/P_s]

wherein B is a target opening degree of the second throttling element; b is₀The initial opening degree of the second throttling element; the P is_mIs a target discharge temperature of the rotary compressor; the P is_sIs the actual discharge temperature of the rotary compressor.

3. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 1, wherein the target discharge temperature is determined based on a target operating frequency of the rotary compressor.

4. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 3, wherein the target discharge temperature of the rotary compressor is calculated using the following formula:

P_m＝af+b

wherein, the P_mIs a target discharge temperature of the rotary compressor; f is the target operating frequency of the rotor compressor; and a and b are constants.

5. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 1, characterized by further comprising:

selectively increasing the opening degree of the second throttling element when the actual exhaust temperature is equal to or greater than the target exhaust temperature.

6. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 5, wherein the step of selectively increasing the opening degree of the second throttling element when the actual exhaust temperature is equal to or higher than the target exhaust temperature further comprises:

when the actual exhaust temperature is greater than or equal to the target exhaust temperature, acquiring the current operating frequency of the rotor type compressor and the continuous operating duration of the rotor type compressor at the current operating frequency;

comparing the current operation frequency with a preset frequency threshold value and the continuous operation time with a preset time threshold value;

the opening degree of the second throttling element is selectively increased based on the comparison result.

7. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 6, wherein the step of selectively increasing the opening degree of the second throttling element based on the comparison result further comprises:

and when the current operating frequency is smaller than the preset frequency threshold value and the continuous operating time is more than or equal to the preset time threshold value, controlling the rotor type compressor to be increased to the preset oil return frequency for operation and controlling the opening degree of the second throttling element to be increased to the set opening degree.

8. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 7, characterized by further comprising:

and after the rotor type compressor operates at the preset oil return frequency and the second throttling element operates at the set opening degree for a set duration, controlling the rotor type compressor to reduce the frequency to the current operating frequency and controlling the opening degree of the second throttling element to be reduced to the initial opening degree.

9. The refrigerating machine oil circulation amount control method of an air conditioning system according to claim 6, wherein the step of selectively adjusting the opening degree of the second throttling element based on the comparison result further comprises:

and when the current operating frequency is greater than or equal to the preset frequency threshold value and/or the continuous operating time length is smaller than the preset time length threshold value, controlling the second throttling element to keep the initial opening degree.

10. The method of controlling oil circulation amount of a refrigerator of an air conditioning system according to claim 1, wherein the inlet pipe communicates with an outlet of the outdoor heat exchanger, the outlet pipe communicates with an inlet of the indoor heat exchanger, and the first throttling element is disposed between the outlet pipe and the inlet of the indoor heat exchanger.

Technical Field

The invention relates to the technical field of air conditioners, in particular to a method for controlling the circulation volume of refrigerating machine oil of an air conditioning system.

Background

In an air conditioning system, a compressor is the heart of the air conditioning system and is the most important component in the air conditioning system. Once a problem occurs in the compressor, the normal operation of the air conditioner is influenced if the problem occurs, the air conditioner is damaged if the problem occurs, and the 'air leakage' is one of the faults of the compressor.

Taking a rotor type compressor as an example, the compressor includes a driving motor, a cylinder block, a sliding vane and an eccentric rotor, the sliding vane is arranged in the cylinder block and is pressed on the outer surface of the eccentric rotor by a spring, and the space in the cylinder block is divided into a high pressure area and a low pressure area (or called a compression area and a suction area). The cylinder body is also filled with refrigerating machine oil, and the refrigerating machine oil forms an oil film with the thickness of several micrometers in a gap between the sliding sheet and the rotor so as to assist sealing. During operation, the eccentric rotor rolls along the inner wall of the cylinder body under the driving of the motor, and in the rolling process, the volumes of the high-pressure area and the low-pressure area are changed, so that the suction and the discharge of a refrigerant are realized. When the rotor compressor has the phenomenon of gas leakage, part of gas in the high-pressure area flows back to the low-pressure area, so that the discharge pressure of the compressor is not increased, the suction pressure is not increased, and the output capacity of the compressor is seriously influenced. The prior art considers that the phenomenon of 'gas leakage' is mostly caused by the clearance between the sliding vane and the rotor, and the clearance is mostly caused by the physical deformation of the sliding vane.

However, through repeated experiments, observations, analyses and comparisons, the inventor finds that the phenomenon of 'gas leakage' of the compressor is not only related to the physical deformation of the sliding vane, but also has a great relation with the downward pressure of the sliding vane in the compressor. The pressure of the slip sheet is in direct proportion to the spring force and the pressure of the high-pressure area, and under the condition of a certain spring force, when the pressure of the high-pressure area is enough, the sealing effect between the high-pressure area and the low-pressure area is good, and the running effect of the compressor is stable; however, when the pressure in the high-pressure area is insufficient, the sealing effect between the high-pressure area and the low-pressure area is poor, and the phenomenon of air leakage is easy to occur between the high-pressure area and the low-pressure area, so that the actual output capacity of the compressor is greatly reduced, and the operation effect of the air conditioner is seriously influenced. For example, when the compressor is just started, the exhaust temperature is low, the high-low pressure difference of the air conditioning system is not completely established, the thrust of the sliding vane mainly depends on the spring force, the spring force is small, the sealing force between the high-pressure area and the low-pressure area is insufficient, the gap between the sliding vane and the rotor is larger than the thickness of an oil film, the gas leakage amount between the high-pressure area and the low-pressure area is large, the phenomenon of gas leakage occurs, and the output capacity of the compressor and the operation effect of the air conditioner are affected.

Accordingly, there is a need in the art for a new refrigerating machine oil circulation amount control method of an air conditioning system to solve the above-mentioned problems.

Disclosure of Invention

In order to solve the above problems in the prior art, that is, to solve the problem that the conventional rotor compressor is easy to generate air leakage when being started, the invention provides a method for controlling the circulation amount of refrigerating machine oil of an air conditioning system, wherein the air conditioning system comprises the rotor compressor, an outdoor heat exchanger, a first throttling element, an indoor heat exchanger and an oil controller, the oil controller comprises a shell, an inlet pipe, an outlet pipe and an oil return pipe, the inlet pipe, the outlet pipe and the oil return pipe are arranged on the shell, the oil return pipe is communicated with an air suction port of the rotor compressor, a second throttling element is arranged between the oil return pipe and the air suction port,

the control method comprises the following steps:

detecting the actual exhaust temperature of the rotor type compressor after the rotor type compressor is started;

comparing the actual exhaust temperature with a target exhaust temperature of the rotary compressor;

when the actual exhaust temperature is lower than the target exhaust temperature, controlling the second throttling element to increase from an initial opening degree to a target opening degree;

wherein the target opening degree is determined based on the initial opening degree, the actual exhaust temperature, and the target exhaust temperature.

In a preferred embodiment of the method for controlling the amount of oil circulated in the refrigerating machine of the air conditioning system, the target opening degree of the second throttling element is calculated by using the following formula:

B＝B₀×[1+(P_m-P_s)/P_s]

wherein B is a target opening degree of the second throttling element; b is₀1, the initial opening degree of the second throttling element; the P is_mIs a target discharge temperature of the rotary compressor; the P is_sIs the actual discharge temperature of the rotary compressor.

In a preferred embodiment of the refrigerating machine oil circulation amount control method of the air conditioning system, the target discharge temperature is determined based on a target operating frequency of the rotary compressor.

In a preferred embodiment of the method for controlling the circulation amount of refrigerating machine oil in the air conditioning system, the target discharge temperature of the rotary compressor is calculated by using the following formula:

P_m＝af+b

wherein, the P_mIs a target discharge temperature of the rotary compressor; f is the target operating frequency of the rotor compressor; and a and b are constants.

In a preferable embodiment of the method for controlling a circulation amount of refrigerating machine oil in an air conditioning system, the method further includes: selectively increasing the opening degree of the second throttling element when the actual exhaust temperature is equal to or greater than the target exhaust temperature.

In a preferred embodiment of the refrigerating machine oil circulation amount control method of the air conditioning system, the step of "selectively increasing the opening degree of the second throttling element when the actual exhaust temperature is equal to or higher than the target exhaust temperature" further includes:

when the actual exhaust temperature is greater than or equal to the target exhaust temperature, acquiring the current operating frequency of the rotor type compressor and the continuous operating duration of the rotor type compressor at the current operating frequency;

comparing the current operation frequency with a preset frequency threshold value and the continuous operation time with a preset time threshold value;

the opening degree of the second throttling element is selectively increased based on the comparison result.

In a preferred embodiment of the refrigerating machine oil circulation amount control method of the air conditioning system, the step of "selectively increasing the opening degree of the second throttling element based on the comparison result" further includes:

and when the current operating frequency is smaller than the preset frequency threshold value and the continuous operating time is more than or equal to the preset time threshold value, controlling the rotor type compressor to be increased to the preset oil return frequency for operation and controlling the opening degree of the second throttling element to be increased to the set opening degree.

In a preferable embodiment of the method for controlling a circulation amount of refrigerating machine oil in an air conditioning system, the method further includes:

and after the rotor type compressor operates at the preset oil return frequency and the second throttling element operates at the set opening degree for a set duration, controlling the rotor type compressor to reduce the frequency to the current operating frequency and controlling the opening degree of the second throttling element to be reduced to the initial opening degree.

In a preferred embodiment of the refrigerating machine oil circulation amount control method of the air conditioning system, the step of "selectively adjusting the opening degree of the second throttling element based on the comparison result" further includes:

and when the current operating frequency is greater than or equal to the preset frequency threshold value and/or the continuous operating time length is smaller than the preset time length threshold value, controlling the second throttling element to keep the initial opening degree.

In a preferred technical scheme of the refrigerating machine oil circulation amount control method of the air conditioning system, the inlet pipe is communicated with an outlet of the outdoor heat exchanger, the outlet pipe is communicated with an inlet of the indoor heat exchanger, and the first throttling element is arranged between the outlet pipe and the inlet of the indoor heat exchanger.

It can be understood by those skilled in the art that in a preferred embodiment of the present invention, the air conditioning system includes a rotor compressor, an outdoor heat exchanger, a first throttling element, an indoor heat exchanger, and an oil controller, the oil controller includes a housing, and an inlet pipe, a liquid outlet pipe, and an oil return pipe disposed in the housing, the oil return pipe is communicated with an air suction port of the rotor compressor, and a second throttling element is disposed between the oil return pipe and the air suction port. The method for controlling the circulation amount of the cooling oil comprises the following steps: detecting the actual exhaust temperature of the rotor type compressor after the rotor type compressor is started; comparing the actual exhaust temperature with the target exhaust temperature of the rotor compressor; when the actual exhaust temperature is lower than the target exhaust temperature, controlling the second throttling element to increase from the initial opening degree to the target opening degree; wherein the target opening degree is determined based on the initial opening degree, the actual exhaust temperature, and the target exhaust temperature.

The control method can improve the thickness of an oil film in the compressor in a mode of increasing the oil return amount when the rotor type compressor is started, guarantee the sealing effect between a high pressure area and a low pressure area in the starting process of the compressor, avoid the phenomenon of air leakage of the compressor, and improve the actual output capacity of the compressor and the operation effect of an air conditioning system. Specifically, when the compressor is just started, the exhaust temperature is low, the high-low pressure difference is not completely established, the thrust of the sliding vane mainly depends on the spring force, the spring force is not enough to form sealing between the high-low pressure area, and at the moment, the gap between the sliding vane and the rotor is larger than the thickness of an oil film between the sliding vane and the rotor, so that the air leakage condition is caused. The actual exhaust temperature of the compressor is compared with the target exhaust temperature after the compressor is started, and when the actual exhaust temperature is lower than the target exhaust temperature, the exhaust pressure of the compressor is proved to be lower, the thickness of an oil film between the sliding blade and the rotor is not enough to make up a gap between the sliding blade and the rotor, refrigerating machine oil in the air conditioning system needs to be controlled to quickly return to the cylinder body of the compressor, and the oil suction structure of the pump body is ensured to suck sufficient refrigerating machine oil so as to increase the thickness of the oil film. At the moment, the opening is increased by controlling the second throttling element between the oil return pipe and the air suction port of the compressor, the circulation quantity of refrigerating machine oil in the oil control device which flows back to the compressor can be increased, so that the thickness of an oil film between the sliding sheet and the rotor is increased, the sealing between a high pressure area and a low pressure area is ensured, the condition that the compressor is in air leakage is avoided, and the output capacity of the compressor and the operation stability of an air conditioning system are improved.

Furthermore, the target opening degree of the second throttling element is determined based on the initial opening degree, the actual exhaust temperature and the target exhaust temperature, so that the target opening degree of the second throttling element can be matched with the current high-low pressure difference, the optimal circulation amount of the refrigerating machine oil is realized on the premise of ensuring the sufficient oil film thickness, the condition that the refrigerant circulation efficiency is obstructed due to the overlarge refrigerating machine oil circulation amount is avoided, and the energy efficiency level of the air conditioning system is ensured.

Further, when the actual exhaust temperature is greater than the target exhaust temperature, the current operation frequency of the compressor and the continuous operation duration of the current operation frequency are further obtained, whether the compressor continuously operates for a certain time at a low frequency can be judged, and after the compressor operates for a period of time at the low frequency, the refrigerating machine oil quantity in the compressor is reduced along with the discharge of a refrigerant, so that the compressor is easily abraded. At the moment, the compressor is controlled to operate after the compressor is raised to the preset oil return frequency, and the opening degree of the second throttling element is controlled to be increased to the set opening degree, so that the flowing speed of the refrigerant can be increased, the circulation quantity of the refrigerating machine oil in the oil controller which flows back to the compressor is increased, and the abrasion of the compressor is avoided.

Drawings

The cooling oil circulation amount control method of the air conditioning system of the present invention will be described with reference to the accompanying drawings. In the drawings:

FIG. 1 is a system diagram of an air conditioning system of the present invention;

FIG. 2 is a cross-sectional view of the rotary compressor of the present invention;

FIG. 3 is a flow chart of a method for controlling the amount of oil circulation in a refrigerator of an air conditioning system according to the present invention;

fig. 4 is a logic diagram of a refrigerating machine oil circulation amount control method of an air conditioning system according to the present invention.

List of reference numerals

1. A rotor type compressor; 11. a cylinder body; 12. sliding blades; 13. a spring; 14. an eccentric rotor; 15. a crankshaft; 16. an air suction port; 17. an exhaust port; 2. a four-way valve; 3. an outdoor heat exchanger; 4. a first throttling element; 5. a bridge rectifier circuit; 6. an oil controller; 61. an inlet pipe; 62. an outlet pipe; 63. an oil return pipe; 7. an indoor heat exchanger; 8. a second throttling element.

Detailed Description

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention. For example, although the steps of the method of the present invention are described in detail below, those skilled in the art can combine, separate and change the order of the above steps without departing from the basic principle of the present invention, and the modified technical solution does not change the basic concept of the present invention and thus falls into the protection scope of the present invention.

It should be noted that in the description of the present invention, the terms of direction or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Furthermore, it should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

First, referring to fig. 1 and 2, the structure of the air conditioning system of the present invention will be described.

As shown in fig. 1, fig. 1 is a system diagram of an air conditioning system, which includes a rotary compressor 1 (hereinafter, simply referred to as a compressor 1), a four-way valve 2, an outdoor heat exchanger 3, a first throttling element 4, a bridge rectifier line 5, an oil controller 6, an indoor heat exchanger 7, and a second throttling element 8. The oil controller 6 comprises a shell, and an inlet pipe 61, an outlet pipe 62 and an oil return pipe 63 which are arranged on the shell, wherein the inlet pipe 61 extends from the top of the shell, the outlet pipe 62 and the oil return pipe 63 both extend from the bottom of the shell, and the extending height of the outlet pipe 62 is greater than that of the oil return pipe 63. The bridge type rectifying pipeline 5 is in a bridge type structure formed by four pipelines, and each pipeline is provided with a one-way valve (5a-5 d). In this application, the first throttling element 4 is an electronic expansion valve, and the second throttling element 8 may be an electronic expansion valve or an electromagnetic valve with a controllable opening degree.

Referring to fig. 2, fig. 2 is a sectional view of the rotor type compressor 1. The rotor compressor 1 mainly includes a cylinder 11, a driving motor (not shown in the figure) disposed in the cylinder 11, a crankshaft 15, an eccentric rotor 14, a sliding vane 12 and a spring 13, wherein the cylinder 11 is provided with an air suction port 16 and an air discharge port 17, the driving motor is in transmission connection with the crankshaft 15, the eccentric rotor 14 is sleeved on the crankshaft 15, the sliding vane 12 is pressed on the eccentric rotor 14 through the elastic force of the spring 13, thereby dividing the cylinder 11 into a high pressure region and a low pressure region. The cylinder 11 is also filled with a refrigerating machine oil which forms an oil film having a thickness of several micrometers between the vane 12 and the eccentric rotor 14. During operation, the eccentric rotor 14 rolls along the inner wall of the cylinder 11 under the driving of the crankshaft 15, and the volumes of the high-pressure area and the low-pressure area are constantly changed during the rolling process, so that the suction and the discharge of a refrigerant are realized.

Referring back to fig. 1, in the air conditioning system, in the cooling mode, the exhaust port of the compressor 1 is communicated with the inlet of the outdoor heat exchanger 3 through the four-way valve 2, the outlet of the outdoor heat exchanger 3 is communicated with the inlet pipe 61 of the oil controller 6 through the one-way valve 5a of the bridge rectifier pipeline 5, the outlet pipe 62 of the oil controller 6 is communicated with the inlet of the first throttling element 4, the outlet of the first throttling element 4 is communicated with the inlet of the indoor heat exchanger 7 through the one-way valve 5c, the outlet of the indoor heat exchanger 7 is communicated with the suction port of the compressor 1 through the four-way valve 2, and the oil return pipe 63 of the oil controller 6 is communicated with the suction port of the compressor 1 through the second throttling element 8.

When the air conditioning system is in refrigeration operation, gaseous refrigerant mixed with refrigerating machine oil discharged by the compressor 1 enters the outdoor heat exchanger 3 through the four-way valve 2 and is liquefied into liquid refrigerant, and the liquid refrigerant enters the shell of the oil controller 6 through the one-way valve 5a and the inlet pipe 61. The liquid refrigerant entering the oil controller 6 has a trace amount of flash, most of the liquid refrigerant is still in a liquid state, the refrigerator oil in the oil controller 6 can be layered with the liquid refrigerant, the refrigerator oil is arranged at the lower layer, the middle layer is the liquid refrigerant, and the upper layer is the gaseous refrigerant. After being throttled by the outlet pipe 62 and the first throttling element 4, the gaseous refrigerant and the liquid refrigerant enter the indoor heat exchanger 7 through the one-way valve 5c and are vaporized into the gaseous refrigerant, and the gaseous refrigerant enters the suction port of the compressor 1 through the four-way valve 2, so that the circulation of the refrigerant is realized. The refrigerating machine oil at the lowest layer of the oil controller 6 enters the air suction port of the compressor 1 through the second throttling element 8, and the circulation of the refrigerating machine oil is realized.

In the heating mode, an exhaust port of the compressor 1 is communicated with an inlet of an indoor heat exchanger 7 through a four-way valve 2, an outlet of the indoor heat exchanger 7 is communicated with an inlet pipe 61 of an oil controller 6 through a one-way valve 5b of a bridge rectifier pipeline 5, an outlet pipe 62 of the oil controller 6 is communicated with an inlet of a first throttling element 4, an outlet of the first throttling element 4 is communicated with an inlet of an outdoor heat exchanger 3 through a one-way valve 5d, an outlet of the outdoor heat exchanger 3 is communicated with an air suction port of the compressor 1 through the four-way valve 2, and an oil return pipe 63 of the oil controller 6 is communicated with an air suction port of the compressor 1 through a second throttling element 8.

When the air conditioning system is operated for heating, a gaseous refrigerant mixed with refrigerating machine oil and discharged from the compressor 1 enters the indoor heat exchanger 7 through the four-way valve 2 and is liquefied into a liquid refrigerant, and the liquid refrigerant enters the shell of the oil controller 6 through the one-way valve 5b and the inlet pipe 61. The liquid refrigerant entering the oil controller 6 has a trace amount of flash, most of the liquid refrigerant is still in a liquid state, the refrigerator oil in the oil controller 6 can be layered with the liquid refrigerant, the refrigerator oil is arranged at the lower layer, the middle layer is the liquid refrigerant, and the upper layer is the gaseous refrigerant. After being throttled by the outlet pipe 62 and the first throttling element 4, the gaseous refrigerant and the liquid refrigerant enter the outdoor heat exchanger 3 through the one-way valve 5d and are vaporized into the gaseous refrigerant, and the gaseous refrigerant enters the suction port of the compressor 1 through the four-way valve 2 to realize the circulation of the refrigerant. The refrigerating machine oil at the lowest layer of the oil controller 6 enters the air suction port of the compressor 1 through the second throttling element 8, and the circulation of the refrigerating machine oil is realized.

It will be understood by those skilled in the art that although the air conditioning system of the present application is described in conjunction with the specific configuration, this is not intended to limit the scope of the present application, and those skilled in the art may add or delete one or more components or adjust the position of one or more components based on the configuration without departing from the principles of the present application. For example, the oil controller 6 may be replaced by another structure in the prior art, and the position of the oil controller may be between the rotary compressor 1 and the outdoor heat exchanger 3. For another example, the four-way valve 2 may not be provided in the air conditioning system, and accordingly, two lines need to be omitted from the bridge-type rectifying line 5.

The refrigerating machine oil circulation amount control method according to the present application will be described with reference to fig. 3 and 4. Fig. 3 is a flowchart of a refrigerating machine oil circulation amount control method of an air conditioning system according to the present invention; fig. 4 is a logic diagram of a refrigerating machine oil circulation amount control method of an air conditioning system according to the present invention.

As described in the background art, when the conventional rotor compressor is just started, because the exhaust temperature is low, the high-low pressure difference of an air conditioning system is not completely established, the thrust of the sliding vane is mainly provided by a spring, which results in insufficient sealing between the high-pressure region and the low-pressure region, and the gap between the sliding vane and the rotor is greater than the oil film thickness of the refrigerating machine oil, which easily causes the air leakage of the compressor, and affects the output capacity of the compressor and the operation effect of the air conditioner. In order to solve the above problems, the method for controlling the circulation amount of the refrigerating machine oil mainly comprises the following steps:

s100, detecting the actual exhaust temperature of the rotor type compressor after the rotor type compressor is started; for example, after the rotor type compressor is started, the actual discharge temperature of the rotor type compressor is detected by a temperature sensor provided at the discharge port of the compressor.

S200, comparing the actual exhaust temperature with the target exhaust temperature of the rotor compressor; for example, the target discharge temperature is determined by parameters such as outdoor ambient temperature or target operating frequency of the compressor, and after the actual discharge temperature of the compressor is detected, a signal of the actual discharge temperature is transmitted to a controller of the air conditioning system to be compared with the target discharge temperature.

S300, when the actual exhaust temperature is lower than the target exhaust temperature, controlling the second throttling element to increase from the initial opening degree to the target opening degree; for example, when the actual exhaust temperature is lower than the target exhaust temperature as a result of the comparison, it is proved that the exhaust pressure of the compressor is lower, the pressure of a high pressure region in a cylinder is lower, and the sliding vane is mainly pushed by the spring force, so that the clearance between the sliding vane and the rotor is larger than the thickness of an oil film between the sliding vane and the rotor, and the air leakage is easily generated to affect the output capacity of the compressor. At this time, by controlling the second throttling element to increase from the initial opening degree to the target opening degree, the return flow rate of the refrigerating machine oil in the oil controller can be increased, and the thickness of the oil film in the compressor can be ensured.

As can be seen from the above description, the control method of the present application can increase the oil film thickness in the compressor in a manner of increasing the oil circulation volume of the refrigerating machine when the rotor type compressor is started, ensure the sealing effect between the high pressure region and the low pressure region in the starting process of the compressor, avoid the occurrence of the air leakage condition of the compressor, and improve the actual output capacity of the compressor and the operation effect of the air conditioning system.

Specifically, when the compressor is just started, the exhaust temperature is low, the high-low pressure difference is not completely established, the thrust of the sliding vane mainly depends on the spring force, the spring force is not enough to form sealing between the high-low pressure area, and at the moment, the gap between the sliding vane and the rotor is larger than the thickness of an oil film between the sliding vane and the rotor, so that the air leakage condition is caused. The actual exhaust temperature of the compressor and the target exhaust temperature are compared after the compressor is started, and when the actual exhaust temperature is lower than the target exhaust temperature, the exhaust pressure of the compressor is lower, the thickness of an oil film between the sliding vane and the rotor is thinner, the effect of sealing a high-pressure area and a low-pressure area is not enough, refrigerating machine oil in an air conditioning system needs to be controlled to quickly return to the cylinder body of the compressor, and the pump body oil absorption structure is ensured to absorb sufficient refrigerating machine oil so as to increase the thickness of the oil film. At the moment, the opening is increased by controlling the second throttling element between the oil return pipe and the air suction port of the compressor, the circulation quantity of the refrigerating machine oil in the oil controller which flows back to the compressor can be increased, the oil film thickness in the compressor is ensured to be enough to seal and isolate a high-pressure area and a low-pressure area, the phenomenon of air leakage of the compressor is avoided, and the output capacity of the compressor and the operation stability of an air conditioning system are improved.

A preferred embodiment of the refrigerating machine oil circulation amount control method according to the present invention will be described below.

In a more preferred embodiment, the target opening degree is determined based on the initial opening degree, the actual exhaust temperature, and the target exhaust temperature. Specifically, the target opening degree of the second throttling element is calculated using the following equation:

B＝B₀×[1+(P_m-P_s)/P_s] (1)

in the formula (1), B is a target opening degree of the second throttling element; b is₀Is the initial opening of the second throttling element; p_mIs the target discharge temperature of the rotary compressor; p_sIs the actual discharge temperature of the rotary compressor.

The target opening degree of the second throttling element is determined based on the initial opening degree, the actual exhaust temperature and the target exhaust temperature, so that the target opening degree of the second throttling element can be matched with the high-low pressure difference of the current compressor, the optimal circulation amount of the refrigerating machine oil is realized on the premise of ensuring the sufficient oil film thickness, the condition that the refrigerant circulation efficiency is hindered due to the overlarge refrigerating machine oil circulation amount is avoided, and the energy efficiency level of an air conditioning system is ensured. When the difference between the actual exhaust temperature and the target exhaust temperature is large, accordingly, the exhaust pressure is low, the high-low pressure difference is small, and a second throttling element is required to be opened by a large opening degree on the basis of the current opening degree so as to enable more refrigerating machine oil to flow back; when the difference between the actual exhaust temperature and the target exhaust temperature is small, the difference between the actual exhaust temperature and the target exhaust temperature is proved to be not large, correspondingly, the exhaust pressure is high, the high-low pressure difference is large, and the second throttling element is opened by a small opening degree on the basis of the current opening degree, so that excessive refrigerating machine oil backflow is avoided.

Of course, the above-mentioned manner of determining the target opening degree by fitting the formula is not exclusive, and in other embodiments, a person skilled in the art may also determine the target opening degree based on other manners as long as the determination manner can embody the relationship between the actual exhaust gas temperature and the target opening degree. For example, it is also possible to generate a comparison table between the target opening degree and the actual exhaust gas temperature and/or the target exhaust gas temperature based on test data, and then determine the target opening degree by table lookup.

Further, in another more preferred embodiment, the target discharge temperature is determined based on a target operating frequency of the rotary compressor. Specifically, the target discharge temperature of the rotary compressor is calculated using the following formula:

P_m＝af+b (2)

wherein, P_mIs a target discharge temperature of the rotary compressor; f is the target operating frequency of the rotor compressor; a. b is a constant.

For example, the above formula (2) can be determined as follows: recording parameters such as energy consumption of the compressor under the working conditions that the compressor works at different target operation frequencies, and recording the exhaust temperature of the state as the target exhaust temperature of the compressor under the working conditions when the energy consumption of the compressor reaches the better state. And after the test is finished, classifying and fitting the multiple groups of data, and finally fitting to obtain a formula (2) of the target exhaust temperature.

Of course, there are other ways of determining the target exhaust temperature in the art, and other methods may be used in the present application as long as they are effective in determining the target exhaust temperature. For example, the target discharge temperature is determined by a fitting equation of the target discharge temperature and the outdoor ambient temperature, or the target discharge temperature is determined by a fitting equation of the target discharge temperature and the frequency and the outdoor ambient temperature in combination, or the like.

Further, in another preferred embodiment, the control method further includes: the opening degree of the second throttling element is selectively increased when the actual exhaust temperature is equal to or greater than the target exhaust temperature.

Specifically, when the actual exhaust temperature is greater than or equal to the target exhaust temperature, the current operating frequency of the rotor type compressor and the continuous operating duration of the rotor type compressor at the current operating frequency are obtained; comparing the current operation frequency with a preset frequency threshold value and the continuous operation time with a preset time threshold value; when the current operating frequency is less than the preset frequency threshold value and the continuous operating time is more than or equal to the preset time threshold value, controlling the rotor type compressor to be increased to the preset oil return frequency, controlling the opening degree of the second throttling element to be increased to the set opening degree, keeping the state for the set time, then controlling the rotor type compressor to be decreased to the operating frequency before the frequency increase, and controlling the opening degree of the second throttling element to be decreased to the initial opening degree; and when the current running frequency is greater than or equal to the preset frequency threshold value and/or the continuous running time is smaller than the preset time threshold value, controlling the second throttling element to keep the initial opening.

For example, when the actual exhaust temperature is greater than or equal to the target exhaust temperature, it is proved that the exhaust temperature of the compressor is higher, the pressure of the high-pressure region is correspondingly higher, the thrust force of the slide sheet is provided by the spring force and the high-pressure region at the same time, the clearance between the slide sheet and the rotor is smaller, the sealing effect between the high-pressure region and the low-pressure region is better, and the circulation amount of the refrigerating machine oil needs to be further controlled by referring to other parameters. At this time, by acquiring the current operating frequency of the compressor and the continuous operating time at the current operating frequency, it can be determined whether the compressor is continuously operated for a certain time in the low-frequency state.

When the current operating frequency of the compressor is less than the preset frequency threshold and the continuous operating time is greater than or equal to the preset time threshold, the compressor is proved to have been operated at a low frequency for a period of time, the oil quantity of a refrigerating machine in the compressor is reduced along with the discharge of a refrigerant, and the compressor is easily abraded. At the moment, the compressor is controlled to be operated after the compressor is controlled to be raised to the preset oil return frequency, and the opening degree of the second throttling element is controlled to be increased to the set opening degree, so that the flowing speed of the refrigerant can be increased, the circulation quantity of the refrigerating machine oil in the oil controller which flows back to the compressor is increased, and the abrasion of the compressor is avoided. After the compressor runs at the preset oil return frequency and the state that the second throttling element is increased to the set opening degree continues for the set time length, the frequency of the compressor is controlled to be reduced to the frequency before the frequency is increased, and the opening degree of the second throttling element is controlled to be reduced to the initial opening degree, so that the problem that the efficiency of the air conditioning system is reduced due to the fact that the circulation amount of refrigerating machine oil is too large is avoided, and the running stability of the air conditioning system is guaranteed.

When the current operation frequency of the compressor is greater than or equal to the preset frequency threshold and/or the continuous operation time length is smaller than the preset time length threshold, the amount of the refrigerating machine oil in the compressor is sufficient, and the operation of increasing the circulating amount of the refrigerating machine oil is not required to be executed. At this time, the compressor and the second throttling element may be controlled to maintain the current operation state.

It should be noted that, although specific values are not given for the preset frequency threshold, the preset oil return frequency, the preset time threshold, the set opening degree, and the set time, this is not insufficient in the disclosure of the present application, and on the contrary, a person skilled in the art may determine the parameters based on a specific model of the compressor, an outdoor environment temperature, and the like, so that the parameters may be applicable to a more specific application scenario.

One possible implementation of the control method of the present invention is described below with reference to fig. 4. Fig. 4 is a logic diagram of a refrigerating machine oil circulation amount control method of an air conditioning system according to the present invention.

In one possible embodiment, as shown in FIG. 4, the second throttling element is at an initial opening B after the compressor is started₀First, step S10 is executed: obtaining a target operating frequency f and an actual discharge temperature P of a compressor_s→ then step S20 is performed: calculating a target discharge temperature P of the compressor based on the target operating frequency_m→ the target exhaust gas temperature P is calculated_mAfter that, the air conditioner is started to work,step S30 is executed: comparison P_sAnd P_mSize of → when P_s＜P_mWhen this is true, step S31 is executed: controlling the second throttling element to be opened from the initial opening B₀Increase to the target opening B → otherwise, step S32 is executed: continuing to acquire the current operating frequency f of the compressor_dAnd duration t → of current operation frequency f when obtaining the current operation frequency_dAnd after the continued operation time period t, step S40 is executed: comparing the current operating frequency f_dThe preset oil return frequency F, the continuous operation time T and the preset time threshold T₁Size of → when f_dLess than F and T is more than or equal to T₁If not, step S41 is executed: controlling the second throttling element to maintain the initial opening degree B₀→ otherwise, perform step S42: controlling the compressor to raise the frequency to a preset oil return frequency F, and controlling the opening degree of the second throttling element from an initial opening degree B₀Increase to a set opening degree B₁Immediately thereafter, step S50 is executed: comparing the duration T' of the above-mentioned operation state with a set time length T₂Size → when T' ≧ T₂When this is true, step S51 is executed: controlling compressor frequency down to operating frequency f_dThe opening degree of the second throttling element is reduced to an initial opening degree B₀Otherwise, return is made to the determination step of continuing to perform step S50.

It should be noted that the controller for executing the control method may be a controller dedicated to execute the method of the present invention, a controller of an existing air conditioning system, or a functional module or functional unit of a general controller.

It will be understood by those skilled in the art that although the specific structure of the controller is not illustrated in the above embodiments, the controller of the air conditioning system may also include other known structures, such as a processor, a memory, etc., wherein the memory includes, but is not limited to, a random access memory, a flash memory, a read only memory, a programmable read only memory, a volatile memory, a non-volatile memory, a serial memory, a parallel memory or a register, etc., and the processor includes, but is not limited to, a CPLD/FPGA, a DSP, an ARM processor, a MIPS processor, etc. Such well-known structures are not shown in the drawings in order to not unnecessarily obscure embodiments of the present disclosure.

In addition, although the foregoing embodiments describe the steps in the above sequential order, those skilled in the art can understand that, in order to achieve the effect of the present embodiment, different steps need not be executed in such an order, and they may be executed simultaneously (in parallel) or in reverse order, and these simple changes are within the scope of the present invention. For example, the step of comparing the current operating frequency with the preset frequency threshold and the step of comparing the continuous operating time with the preset time threshold may be executed simultaneously or sequentially.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.