A control system and control method for air conditioner oil return

Abstract

The present invention discloses a control system and control method for oil return of air conditioner, the control system comprises a first port of a compressor connected with a first port of an enthalpy increasing electronic expansion valve and a first port of an oil-gas separator through a pipeline, a second port of the enthalpy increasing electronic expansion valve connected with a second port of an oil-gas separator and a first port of an oil return cooler through a pipeline, a third port of the oil-gas separator connected with a second port of the oil return cooler through a pipeline, a third port of the oil return cooler connected with a second port of the compressor through a pipeline, and an oil return electronic expansion valve arranged on a pipeline between the compressor and the oil-gas separator. The oil is separated, the purity of the oil return is improved, the influence on the volume of the air intake after the oil return is reduced, and the overall operation capacity is improved; the electric heating component provides heat to the air conditioner when it is started at low temperature, thereby improving the superheat of the air intake and exhaust, and reducing the time when the compressor is in the exhaust with liquid operation.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent control, and in particular to a control system and a control method of an air-conditioning oil return. Background Art

[0002] When the air conditioner is started and operated at low temperature in winter, the compressor is prone to oil shortage and slow heating speed. Long-term low-temperature standing will cause the refrigerant to migrate. Due to the low outdoor ambient temperature, the refrigerant will be concentrated in the outdoor compressor, heat exchanger, oil separator and gas-liquid separator. In the compressor with more oil storage, the lubricating oil and liquid refrigerant are in a miscible state, that is, a large amount of liquid refrigerant is mixed in the oil pool.

[0003] When the compressor starts, the refrigerant dissolved in the lubricating oil will boil, causing the oil layer to foam. The foam carries a large amount of lubricating oil into the intake air, and then is discharged through the shell exhaust port. If the oil separation efficiency is insufficient, a large amount of lubricating oil will enter the heat exchanger, causing the compressor to lack oil, thereby reducing the reliability of the compressor and the heat exchange efficiency of the system. Moreover, in the low temperature environment, the liquid refrigerant in the external unit pipeline and various containers absorbs little heat during evaporation, and cannot achieve intake air overheating, resulting in liquid in the intake and exhaust air, seriously affecting the use. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art solutions, an embodiment of the present invention provides an air-conditioning oil return control system and a control method thereof.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] In a first aspect, an embodiment of the present invention provides an air-conditioning oil return control system, the control system comprising a compressor, an oil-gas separator, an oil return electronic expansion valve, an enthalpy increasing electronic expansion valve and an oil return cooler; a first port of the compressor is communicated with a first port of the enthalpy increasing electronic expansion valve and a first port of the oil-gas separator through a pipeline, a second port of the enthalpy increasing electronic expansion valve is communicated with a second port of the oil-gas separator and a first port of the oil return cooler through a pipeline, a third port of the oil-gas separator is communicated with a second port of the oil return cooler through a pipeline, and a third port of the oil return cooler is communicated with a second port of the compressor through a pipeline;

[0007] The oil return electronic expansion valve is arranged on a pipeline between the compressor and the oil-gas separator.

[0008] In a second aspect, an embodiment of the present invention further provides a method for controlling oil return of an air conditioner, the control method being applied to the control system for oil return of an air conditioner of the first aspect, the control method comprising:

[0009] Obtaining an exhaust superheat value of the compressor, and determining whether the exhaust superheat value satisfies a superheat value condition;

[0010] If the exhaust gas superheat value satisfies the superheat value condition, controlling the oil-gas separator to adjust to the first superheat value;

[0011] The opening value of the oil return electronic expansion valve is controlled to be the same as the opening value of the enthalpy increase electronic expansion valve;

[0012] Obtaining the suction and exhaust temperature values ​​of the compressor, and determining whether the suction and exhaust temperature values ​​of the compressor meet the temperature condition;

[0013] If the suction and exhaust temperatures of the compressor meet the temperature condition, the compressor is controlled to maintain the current operating state.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The oil separation can improve the purity of the oil return, reduce the impact of the oil return on the suction volume, and improve the overall operating capacity. Since the electric heating component provides heat for the air conditioner when it is started at low temperature, it accelerates the superheat of the suction and exhaust, reduces the time the compressor is in the exhaust with liquid operation, ensures the reliability of the compressor, and improves the user's comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0017] Figure 1 It is a structural diagram of the control system of the air conditioner oil return according to the embodiment.

[0018] Figure 2 A flow chart of a method for controlling oil return of an air conditioner according to an embodiment of the present invention is provided.

[0019] Figure 3 It is a flow chart of controlling the opening value of the oil return electronic expansion valve to be the same as the opening value of the enthalpy increase electronic expansion valve according to the embodiment.

[0020] Figure ID

[0021] 1. Compressor; 2. Exhaust pressure sensor; 3. Exhaust temperature sensor; 4. Return oil cooler; 5. Oil-gas separator; 51. Electric heating rod; 52. Oil pool temperature sensor; 6. Return oil electronic expansion valve; 7. Float oil separator; 71. Float; 72. Return oil valve; 8. Four-way reversing valve; 9. Outdoor heat exchanger; 10. Enthalpy increase electronic expansion valve; 11. Enthalpy increase economizer; 12. Indoor heat exchanger; 13. Gas-liquid separator; 14. Enthalpy increase temperature sensor; 15. Enthalpy increase pressure sensor; 16. Intake temperature sensor; 17. Intake pressure sensor. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0024] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0025] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] The embodiment of the present invention provides an air conditioner oil return control system. Figure 1 As shown, the control system specifically includes a compressor 1 , an oil-gas separator 5 , an oil return electronic expansion valve 6 , an enthalpy increase electronic expansion valve 10 and an oil return cooler 4 .

[0027] The first port of the compressor 1 is connected to the first port of the enthalpy increasing electronic expansion valve 10 and the first port of the oil-gas separator 5 through a pipeline, the second port of the enthalpy increasing electronic expansion valve 10 is connected to the second port of the oil-gas separator 5 and the first port of the return oil cooler 4 through a pipeline, the third port of the oil-gas separator 5 is connected to the second port of the return oil cooler 4 through a pipeline, the third port of the return oil cooler 4 is connected to the second port of the compressor 1 through a pipeline, and the return oil electronic expansion valve 6 is arranged on the pipeline between the compressor 1 and the oil-gas separator 5.

[0028] The oil-gas separator 5 includes an electric heating component, an oil pool temperature sensor 52 and a control component. The electric heating component and the oil pool temperature sensor 52 are built in the first oil pool cavity in the oil-gas separator 5, and the control component is controlled and connected with the electric heating component and the oil pool temperature sensor 52.

[0029] Specifically, when the electric heating component heats the oil in the first oil pool cavity, the power required for the heating process can be adjusted. The oil in the first oil pool cavity is heated by the electric heating component, and the oil pool temperature sensor 52 monitors the temperature of the oil in the first oil pool cavity in real time to determine whether the temperature of the oil is at a preset temperature value. If it is lower than the preset temperature value, the control component controls the electric heating component to heat the oil, so that the temperature of the oil is controlled within the preset temperature value to prevent the oil from being cooled.

[0030] The control system also includes a float oil separator 7, which is arranged on the pipeline between the compressor 1 and the oil-gas separator 5 or the enthalpy-increasing electronic expansion valve 10. The float oil separator 7 includes an oil return valve 72 and a float 71, and the float 71 is built in the second oil pool cavity of the float oil separator 7. The float 71 plays the role of oil separation and oil level control, and the separated lubricating oil is gathered at the bottom of the oil separation in the second oil pool cavity. The oil return valve 72 is arranged at the second port, and the first valve port of the oil return valve 72 is connected to the second oil pool cavity, and the second valve port of the oil return valve 72 is connected to the second port. If the oil level at the top is higher than the highest limit position of the float 71 in the floating process during the gradual increase of the oil, the oil return valve 72 is opened; on the contrary, if the oil level at the top is not higher than the highest limit position of the float 71 in the floating process during the gradual increase of the oil, the oil return valve 72 is closed. It effectively isolates the high pressure in the exhaust and the low pressure in the suction, preventing oil from being sucked and exhausted when there is no liquid surface.

[0031] In addition, the highest limit position of the float 71 can be customized according to actual conditions.

[0032] The return oil cooler 4 is specifically a plate heat exchanger. After the oil is heated to a set temperature in the oil-gas separator 5, in order to prevent the return oil from affecting the suction superheat, the oil is cooled by the return oil cooler 4. The suction superheat and the return oil volume need to be increased, and the oil is passed through the return oil cooler 4. After the oil is cooled by the return oil cooler 4, the oil can be returned to the compressor 1 for suction mixing.

[0033] According to the attached Figure 1 As shown in the figure, the control system of the embodiment of the present invention also includes a four-way reversing valve 8, an enthalpy increase economizer 11, an indoor heat exchanger 12, a gas-liquid separator 13, an enthalpy increase temperature sensor 14, an enthalpy increase pressure sensor 15, an intake temperature sensor 16 and an intake pressure sensor 17.

[0034] Through the air conditioner oil return control system of the embodiment of the present invention, the oil can be separated, the oil return purity can be improved, and the impact on the volume of the air intake after the oil return is reduced, thereby improving the overall operating capacity. Since the electric heating component provides heat to the air conditioner when it is started at low temperature, the superheat of the air intake and exhaust is accelerated, the time that the compressor 1 is in the exhaust liquid operation is reduced, the reliability of the compressor 1 is guaranteed, and the user's comfort is improved.

[0035] In order to solve the technical problem in the prior art that due to refrigerant migration and low external ambient temperature, the superheat and exhaust pressure of the suction and exhaust air cannot be quickly established, resulting in the indoor environment being unable to heat for a long time, seriously affecting user use, an embodiment of the present invention further provides an air conditioner oil return control method, which is applied to the air conditioner oil return control system of the embodiment of the present invention. For example, the air conditioner oil return control method executes relevant steps through an application installed in the air conditioner oil return control system.

[0036] The specific implementation process of the air conditioner oil return control method provided by the present invention is described in detail below.

[0037] According to the attached Figure 2 and attached Figure 3 As shown, the control method specifically includes:

[0038] The exhaust gas superheat value of compressor 1 is obtained, and it is determined whether the exhaust gas superheat value meets the superheat value condition.

[0039] Specifically, this step is to determine whether the compressor 1 is in an operating state with exhaust gas containing liquid. The judgment condition is to determine whether the exhaust gas superheat value satisfies the superheat value condition. If the exhaust gas superheat value does not satisfy the superheat value condition, it is determined that the compressor 1 is in an operating state with exhaust gas containing liquid at this time, and then it is necessary to increase the superheat of the suction air to prevent the temperature after the oil return from being relatively low, and at the same time increase the oil return amount at this time; conversely, if the exhaust gas superheat value satisfies the superheat value condition, it is determined that the compressor 1 is not in an operating state with exhaust gas containing liquid at this time, and then the next process and the next judgment condition can be executed.

[0040] For example, when the overall air-conditioning system is turned on, the exhaust superheat value at this time is obtained by calculation, and the exhaust superheat value is used to judge whether the superheat value condition is met. The superheat value condition can be set in advance, or the superheat value condition can be set to a suitable judgment value according to the actual usage status. For example, the superheat value condition is set to whether it exceeds 5°C, that is, the exhaust superheat value>5°C. If the calculated exhaust superheat value is 8°C, it is determined that the exhaust superheat value meets the superheat value condition; if the calculated exhaust superheat value is 4°C, it is determined that the exhaust superheat value does not meet the superheat value condition.

[0041] If the exhaust gas superheat value satisfies the superheat value condition, the superheat value of the oil-gas separator 5 is controlled to be adjusted to the first superheat value.

[0042] Specifically, it is determined whether the exhaust superheat value satisfies the superheat value condition according to the obtained exhaust superheat value. If the judgment result is that the exhaust superheat value satisfies the superheat value condition, it is determined that the compressor 1 is not in an operating state with liquid in the exhaust gas at this time, and then the superheat value of the oil-gas separator 5 is adjusted to be set at the first superheat value, that is, it is determined that the superheat and return oil volume of the suction air do not need to be increased, and then the oil is passed through the return oil cooler 4, and then the oil is cooled by the return oil cooler 4 using the return oil cooling method, and then the oil can be returned to the compressor 1 for suction mixing. In addition, the first superheat value of the embodiment of the present invention can also be set according to actual usage.

[0043] For example, if the exhaust superheat value obtained is specifically 8°C, it is determined that the exhaust superheat value meets the superheat value condition exceeding 5°C. At this time, the superheat value of the oil-gas separator 5 is controlled to be adjusted to 80°C. Specifically, there is no need to increase the superheat of the oil-gas separator 5 to prevent overcooling after the oil return. Therefore, the superheat of the oil-gas separator 5 is reduced to a part, that is, it can be controlled at 80°C.

[0044] The opening value of the oil return electronic expansion valve 6 is controlled to be the same as the opening value of the enthalpy increase electronic expansion valve 10 .

[0045] Specifically, in order to determine whether the return oil cooler 4 has entered the operating state at this time, it is necessary to determine whether the opening value of the enthalpy increasing electronic expansion valve 10 meets the opening value condition. If the judgment result is that the opening value of the enthalpy increasing electronic expansion valve 10 meets the opening value condition, it is determined that the return oil cooler 4 has entered the operating state at this time, and then the opening value of the return oil electronic expansion valve 6 is controlled to be the same as the opening value of the enthalpy increasing electronic expansion valve 10, that is, the return oil pressure and the enthalpy increasing pressure of the oil are the same.

[0046] For example, whether the return oil cooler 4 is in operation is determined based on whether the opening value of the enthalpy increasing electronic expansion valve 10 satisfies the opening value condition. If the opening value of the enthalpy increasing electronic expansion valve 10 is 1 and the opening value condition has been pre-set to 0, it is determined that the opening value of the enthalpy increasing electronic expansion valve 10 is greater than the opening value condition. At this time, the return oil cooler 4 has entered the operation state. Then, the opening value of the return oil electronic expansion valve 6 is controlled to be the same as the opening value of the enthalpy increasing electronic expansion valve 10, that is, the opening value of the return oil electronic expansion valve 6 and the opening value of the enthalpy increasing electronic expansion valve 10 are both 1.

[0047] The suction and exhaust temperature value of the compressor 1 is obtained, and it is determined whether the suction and exhaust temperature value of the compressor 1 meets the temperature condition.

[0048] Specifically, this step is to determine whether the compressor 1 is in an intake and exhaust gas overheating state, and therefore to determine whether the intake and exhaust gas temperature value of the compressor 1 meets the temperature condition as a judgment condition for whether the compressor 1 is in this operating state. If the judgment result is that the intake and exhaust gas temperature value of the compressor 1 does not meet the temperature condition, it is determined that the compressor 1 is in an intake and exhaust gas overheating state at this time, and then it is necessary to control the intake and exhaust gas superheating value and the exhaust gas superheating value of the compressor 1, that is, to increase the opening value of the enthalpy increase electronic expansion valve 10 and the opening value of the oil return electronic expansion valve 6, thereby increasing the enthalpy increase flow rate and reducing the oil return temperature of the oil, until the intake and exhaust gas temperature value of the compressor 1 meets the temperature condition; conversely, if the judgment result is that the intake and exhaust gas temperature value of the compressor 1 meets the temperature condition, it is determined that the compressor 1 is not in an intake and exhaust gas overheating state.

[0049] In addition, the intake and exhaust temperature values ​​in the embodiment of the present invention are specifically intake superheat values ​​and exhaust temperature values.

[0050] For example, based on the obtained suction and exhaust temperature values, the suction and exhaust temperature values ​​are used as a judgment on whether the temperature condition is met, and the temperature condition can also be preset, or the temperature condition can be set at a suitable judgment value according to the actual use status, such as setting the temperature condition to whether the suction superheat value condition is lower than 20°C and the exhaust temperature value condition is lower than 110°C, that is, the suction superheat value <20°C and the exhaust temperature value <110°C. If the obtained suction superheat value is 18°C ​​or the obtained exhaust temperature value is 105°C, it is determined that the suction and exhaust temperature values ​​of compressor 1 meet the temperature condition; if the obtained suction superheat value is 25°C or the obtained exhaust temperature value is 120°C, it is determined that the suction and exhaust temperature values ​​of compressor 1 do not meet the temperature condition.

[0051] If the suction and exhaust temperatures of the compressor 1 meet the temperature condition, the compressor 1 is controlled to maintain the current operating state.

[0052] Specifically, it is determined whether the intake and exhaust temperature value of the compressor 1 satisfies the temperature condition based on the obtained intake and exhaust temperature value of the compressor 1. If the judgment result is that the intake and exhaust temperature value of the compressor 1 satisfies the temperature condition, it is determined that the compressor 1 is not in an intake and exhaust overheating state at this time. At this time, there is no need to increase the opening value of the enthalpy increasing electronic expansion valve 10 and the opening value of the oil return electronic expansion valve 6, and there is no need to increase the enthalpy increasing flow rate and reduce the oil return temperature of the oil. The air conditioner at this time can continue to operate in the current state, so that the oil has a higher separation ability, the oil return purity is improved, and the impact of the oil return on the intake volume is reduced, so as to improve the operation capacity of the air conditioner.

[0053] For example, the suction and exhaust temperature values ​​obtained are that the suction superheat value is 18°C, because the suction superheat value is lower than the suction superheat value condition of 20°C; or, the exhaust temperature value obtained is 105°C, which is lower than the exhaust temperature value condition of 110°C. Therefore, it is determined that the suction and exhaust temperature values ​​of the compressor 1 meet the temperature conditions, and then the control system of the entire air conditioner can continue to operate according to the current state.

[0054] In addition, in the embodiment of the present invention, only one of the suction superheat value and the exhaust temperature value needs to meet the corresponding judgment condition, that is, it is not necessary for the suction superheat value to meet the suction superheat value condition and the exhaust temperature value to meet the exhaust temperature value condition, in order to determine that the suction and exhaust temperature values ​​of the compressor 1 meet the temperature condition. For example, at this time, the suction superheat value meets the suction superheat value condition, while the exhaust temperature value does not meet the exhaust temperature value condition, and at this time, it will be determined that the suction and exhaust temperature values ​​of the compressor 1 meet the temperature condition.

[0055] In a specific embodiment, step S110, obtaining the exhaust gas superheat value of the compressor 1, includes the following steps:

[0056] Receive the exhaust pressure value and exhaust temperature value sent by the sensor.

[0057] Specifically, the sensor of the embodiment of the present invention includes an exhaust pressure sensor 2 and an exhaust temperature sensor 3. The exhaust pressure sensor 2 detects the exhaust pressure value of the compressor 1, and the exhaust temperature sensor 3 detects the exhaust temperature value of the compressor 1. The exhaust pressure value and exhaust temperature value detected by each sensor are collected and recorded.

[0058] For example, when the compressor 1 releases exhaust gas, the exhaust temperature sensor 3 first detects the gas discharged by the compressor 1 to obtain the exhaust temperature value, and then the exhaust pressure sensor 2 detects the gas discharged by the compressor 1 to obtain the exhaust temperature value.

[0059] The exhaust pressure value and the exhaust temperature value are calculated to obtain the exhaust superheat value.

[0060] Specifically, the exhaust temperature value t and the exhaust pressure value p can be used to calculate the exhaust superheat value h. The calculation formula of the suction point enthalpy value h can be expressed by the following formula:

[0061] h=u0+r×p×t

[0062] Among them, u0 is the basic internal energy, the basic internal energy corresponds to the specific coolant selected, and r is the fixed coefficient value in the formula.

[0063] The calculated exhaust gas superheat value is used as a judgment condition for whether the superheat value condition is met, and whether the compressor 1 is in an operating state with exhaust gas containing liquid at this time.

[0064] In a specific embodiment, after obtaining the exhaust gas superheat value of the compressor 1 and determining whether the exhaust gas superheat value meets the superheat value condition, the following steps are also included:

[0065] If the exhaust gas superheat value does not meet the superheat value condition, the superheat value of the oil-gas separator 5 is controlled to be adjusted to a second superheat value.

[0066] Specifically, it is determined whether the exhaust superheat value satisfies the superheat value condition according to the obtained exhaust superheat value. If the judgment result is that the exhaust superheat value does not meet the superheat value condition, it is determined that the compressor 1 is in an operating state with exhaust gas containing liquid, and then the superheat value of the oil-gas separator 5 is controlled to be adjusted to the second superheat value, that is, it is determined that the superheat and return oil volume of the suction gas need to be increased, and then the oil is passed through the return oil cooler 4, and the oil is cooled by the return oil cooling method of the return oil cooler 4, and then the oil can be returned to the compressor 1 for mixing. The second superheat value of the embodiment of the present invention can also be set according to the actual usage.

[0067] For example, if the exhaust superheat value obtained is specifically 4°C, it is determined that the exhaust superheat value does not meet the superheat value condition exceeding 5°C. At this time, it is necessary to control the superheat value of the oil-gas separator 5 to be adjusted to 110°C, and increase the superheat of the oil-gas separator 5 to prevent the oil from being overcooled after returning the oil. Therefore, the superheat value of the oil-gas separator 5 needs to be increased by a part of the superheat value relative to the first superheat value, that is, controlled at 110°C.

[0068] Among them, the superheat value of the first superheat value is lower than the superheat value of the second superheat value because the compressor 1 is in an operating state where the exhaust contains liquid. Therefore, it is necessary to control the superheat value of the oil-gas separator 5 to be adjusted to the second superheat value to prevent the temperature after the oil return from being relatively low.

[0069] In a specific embodiment, after the superheat value of the oil-gas separator 5 is adjusted to the second superheat value, the following steps are further included:

[0070] The enthalpy-increasing electronic expansion valve 10 is controlled to enter a closed state so that the opening value of the enthalpy-increasing electronic expansion valve 10 is set to zero.

[0071] Specifically, since it is determined that the compressor 1 is in an operating state in which the exhaust contains liquid, in addition to increasing the superheat value of the oil-gas separator 5, it is also necessary to control the electronic expansion valve at this time to enter a closed state to prevent the oil temperature from being too low during oil return and failing to reach a suitable temperature value for reflux.

[0072] The oil return electronic expansion valve 6 is controlled to enter a fully open operation state, so as to put the compressor 1 into a high-temperature oil return state.

[0073] Specifically, after the enthalpy increase electronic expansion valve 10 is controlled to enter a closed state, the oil return electronic expansion valve 6 is then controlled to enter a fully open operation state, so as to increase the amount of oil returned, so that more oil can enter the oil-gas separator 5, thereby achieving suction superheating of the compressor 1, and then the exhaust superheat value of the compressor 1 can meet the superheat value condition.

[0074] For example, it is detected that the exhaust superheat value of compressor 1 is 4°C. When the superheat value of the oil-gas separator 5 is adjusted to 110°C, the electronic expansion valve at this time is controlled to enter a closed state to prevent the temperature of the oil return from being too low. Then, the oil return electronic expansion valve 6 is controlled to enter a fully open operation state to increase the oil return volume, so that the compressor 1 at this time enters a high-temperature oil return state.

[0075] It is determined whether the exhaust gas superheat value of the compressor 1 in the high-temperature oil return state after operating for a first preset time meets the superheat value condition.

[0076] Specifically, the compressor 1 in the high-temperature oil return state needs to operate for the first preset time, and then judge again whether the exhaust superheat value of the compressor 1 at this time meets the superheat value condition. If the compressor 1 in the high-temperature oil return state operates for this period of time, the exhaust superheat value meets the superheat value condition, then it is determined that the compressor 1 is not in an operating state with liquid in the exhaust gas, and then there is no need to control the superheat value of the oil-gas separator 5 to adjust the setting to the second superheat value, and there is no need to control the enthalpy increase electronic expansion valve 10 to enter the closed state and control the oil return electronic expansion valve 6 to enter the fully open operating state, and the next process and the next judgment condition can be executed. In addition, the first preset time of the embodiment of the present invention can be set according to actual conditions.

[0077] For example, the compressor 1 in the high-temperature oil return state needs to operate for 60 seconds, and then judge again whether the exhaust superheat value of the compressor 1 at this time meets the superheat value condition. If the exhaust superheat value meets the superheat value condition, the cycle steps of controlling the enthalpy increase electronic expansion valve 10 to enter the closed state and controlling the oil return electronic expansion valve 6 to enter the fully open operation state can be jumped out.

[0078] If the exhaust superheat value of the compressor 1 in the high-temperature oil return state does not meet the superheat value condition after operating for the first preset time, the step of controlling the enthalpy-increasing electronic expansion valve 10 to enter the closed state is returned to execution.

[0079] Specifically, the compressor 1 in the high-temperature oil return state needs to operate for a first preset time. If the exhaust superheat value of the compressor 1 in the high-temperature oil return state still does not meet the superheat value condition after operating for this period of time, it is determined that the compressor 1 is still in an operating state in which the exhaust gas contains liquid, and then the superheat value of the oil-gas separator 5 is continued to be controlled to be adjusted to the second superheat value, and the enthalpy increase electronic expansion valve 10 is controlled to enter a closed state and the oil return electronic expansion valve 6 is controlled to enter a fully open operating state, so that the compressor 1 enters the high-temperature oil return state again and operates for the first preset time, and then it is judged again whether the exhaust superheat value meets the superheat value condition. The cycle step can only be jumped out after the exhaust superheat value meets the superheat value condition.

[0080] In a specific embodiment, the opening value of the oil return electronic expansion valve 6 is controlled to be the same as the opening value of the enthalpy increase electronic expansion valve 10. Figure 3 As shown, the steps include:

[0081] The opening value of the enthalpy-increasing electronic expansion valve 10 is obtained, and it is determined whether the opening value of the enthalpy-increasing electronic expansion valve 10 satisfies an opening value condition.

[0082] Specifically, this step is to detect whether the enthalpy-increasing electronic expansion valve 10 is open to increase enthalpy, and to determine whether the opening value of the enthalpy-increasing electronic expansion valve 10 satisfies the opening value condition, as a judgment condition for whether the return oil cooler 4 enters the operating state. In addition, the opening value condition of the embodiment of the present invention can also be preset, and the opening value condition is specifically whether the opening value of the electronic expansion valve is greater than 0.

[0083] If the judgment result is that the opening value of the enthalpy increasing electronic expansion valve 10 satisfies the opening value condition, the opening value of the oil return electronic expansion valve 6 is controlled to be the same as the opening value of the enthalpy increasing electronic expansion valve 10 .

[0084] Specifically, if the opening value of the enthalpy increasing electronic expansion valve 10 is 1, it is determined whether the opening value condition is met with the opening value of 1. When the opening value condition is pre-set to 0, it can be determined that the opening value of the enthalpy increasing electronic expansion valve 10 is greater than the opening value condition. Then, the opening value of the return oil electronic expansion valve 6 is controlled to be the same as the opening value of the enthalpy increasing electronic expansion valve 10 at this time, that is, the return oil pressure and the enthalpy increasing pressure are equal.

[0085] If the judgment result is that the opening value of the enthalpy-increasing electronic expansion valve 10 does not meet the opening value condition, the enthalpy-increasing pressure is increased to make the opening value of the oil return electronic expansion valve 6 the same as the opening value of the enthalpy-increasing electronic expansion valve 10 .

[0086] Specifically, if the opening value of the enthalpy increase electronic expansion valve 10 is obtained to be lower than 0, it is also determined whether the opening value lower than 0 satisfies the opening value condition. At this time, it can be determined that the opening value of the enthalpy increase electronic expansion valve 10 is less than the opening value condition. Then, the enthalpy increase pressure value needs to be adjusted until the enthalpy increase pressure value is greater than the pressure value of the pump body cavity of the compressor 1, so that the opening value of the return oil electronic expansion valve 6 is the same as the opening value of the enthalpy increase electronic expansion valve 10, thereby putting the return oil cooler 4 into operation.

[0087] In a specific embodiment, increasing the enthalpy increase pressure value comprises the steps of:

[0088] Receive the pump body cavity pressure value of the compressor 1 sent by the sensor.

[0089] Specifically, the enthalpy increase pressure sensor 15 is used to detect the pump cavity pressure value of the compressor 1, and the pump cavity pressure value is P1.

[0090] The oil return electronic expansion valve 6 is controlled to enter an open state, so as to increase the opening value of the enthalpy increase electronic expansion valve 10 to 1.2 to 1.5 times the pump body cavity pressure value of the compressor 1 .

[0091] Specifically, if the opening value of the enthalpy increasing electronic expansion valve 10 does not meet the opening value condition and the return oil cooler 4 has not entered the operating state, the enthalpy increasing electronic expansion valve 10 at this time is controlled to enter the opening state, thereby increasing the enthalpy increasing pressure value (the opening value of the enthalpy increasing electronic expansion valve 10) until the enthalpy increasing pressure value can reach 1.2 to 1.5 times the pump body cavity pressure value, thereby achieving air replenishment and enthalpy increasing.

[0092] In addition, when the enthalpy-increasing electronic expansion valve 10 is closed, the enthalpy-increasing pressure sensor 15 will also enter the operating state and detect the enthalpy-increasing chamber of the compressor 1. The pressure detected by the enthalpy-increasing pressure sensor 15 is the pump body cavity pressure value.

[0093] In a specific embodiment, after obtaining the suction and exhaust temperature value of the compressor 1 and determining whether the suction and exhaust temperature value of the compressor 1 meets the temperature condition, the following steps are also included:

[0094] If the suction and exhaust temperatures of the compressor 1 do not meet the temperature conditions, the opening values ​​of the enthalpy-increasing electronic expansion valve 10 and the oil-returning electronic expansion valve 6 are increased to put the compressor 1 into an enthalpy-increasing pressure state.

[0095] Specifically, if the judgment result is that the suction and exhaust temperature value of the compressor 1 does not meet the temperature condition, it is determined that the compressor 1 is in the suction and exhaust overheat state at this time, so it is necessary to control the suction and exhaust temperature value (suction superheat value and exhaust superheat value) of the compressor 1, that is, to increase the opening value of the enthalpy increase electronic expansion valve 10 and the opening value of the oil return electronic expansion valve 6, so that the compressor 1 enters the enthalpy increase pressure state, and then the enthalpy increase flow rate can be increased and the oil return temperature of the oil can be reduced until the suction and exhaust temperature value of the compressor 1 meets the temperature condition. The temperature condition can also be preset.

[0096] For example, the obtained suction superheat value is 25°C or the obtained exhaust temperature value is 120°C, and the suction superheat value condition in the temperature condition is set to 20°C, and the exhaust temperature value condition in the temperature condition is set to 110°C, it can be judged that the suction superheat value of 25°C does not meet the suction superheat value condition, or the exhaust temperature value of 120° does not meet the suction superheat value condition. At this time, it is necessary to increase the opening value of the enthalpy increase electronic expansion valve 10 and the opening value of the oil return electronic expansion valve 6, so that the compressor 1 enters the enthalpy increase pressure state.

[0097] It is determined whether the suction and exhaust temperature values ​​of the compressor 1 in the enthalpy increase pressure state after operating for a second preset time meet the temperature condition.

[0098] Specifically, the compressor 1 in the enthalpy increase pressure state needs to operate until the second preset time, and then judge again whether the suction and exhaust temperature value of the compressor 1 at this time meets the temperature condition. If the suction and exhaust temperature value of the compressor 1 in the high-temperature oil return state meets the temperature condition after this period of operation, it is determined that the compressor 1 is not in the suction and exhaust overheating state, and then there is no need to control the increase of the opening value of the enthalpy increase electronic expansion valve 10 and the opening value of the oil return electronic expansion valve 6, so that the entire control system can maintain the current state and continue to operate. In addition, the second preset time of the embodiment of the present invention can be set according to actual conditions.

[0099] If the suction and exhaust temperatures of the compressor 1 in the enthalpy increase pressure state do not meet the temperature condition after the second preset operation time, the process returns to the step of increasing the opening values ​​of the enthalpy increase electronic expansion valve 10 and the oil return electronic expansion valve 6.

[0100] Specifically, the compressor 1 in the enthalpy increase pressure state needs to operate until the second preset time. If the intake and exhaust temperature values ​​of the compressor 1 in the enthalpy increase pressure state still do not meet the temperature conditions after operating for this period of time, it is determined that the compressor 1 is still in an intake and exhaust overheating state. Then it is necessary to control and increase the opening value of the enthalpy increase electronic expansion valve 10 and the opening value of the return oil electronic expansion valve 6, so that the compressor 1 enters the enthalpy increase pressure state again and operates for the second preset time. Then, it is judged again whether the intake and exhaust temperature values ​​meet the temperature conditions. The cycle step can only be jumped out after the intake and exhaust temperature values ​​meet the temperature conditions.

[0101] For example, increasing the opening value of the enthalpy-increasing electronic expansion valve 10 and the opening value of the oil return electronic expansion valve 6 means increasing the enthalpy-increasing pressure, so that the enthalpy-increasing flow rate is increased, and the oil return temperature of the oil is reduced. Each time the compressor 1 is in the enthalpy-increasing pressure state, the enthalpy-increasing pressure is increased by 50kpa, and after 30 seconds of operation time, the suction and exhaust temperature values ​​of the compressor 1 are checked again to see whether they meet the temperature conditions, until the suction superheat value is lower than 20°C, or the exhaust temperature value is lower than 110°C, the cycle step can be jumped out.

[0102] The air conditioner oil return control method of the embodiment of the present invention solves the technical problem that the suction and exhaust superheat cannot be quickly established due to the migration of the refrigerant and the low external environment temperature, and the exhaust pressure cannot be established, resulting in the indoor environment being unable to heat for a long time, seriously affecting the user's use. The oil separator has a higher separation ability, can improve the oil return purity, and reduce the impact on the suction volume after the oil return, thereby improving the overall operation capacity.

[0103] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0104] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A control system for oil return of an air conditioner, characterized in that: The control system includes a compressor, an oil-gas separator, an oil return electronic expansion valve, an enthalpy increase electronic expansion valve and an oil return cooler; the first port of the compressor is communicated with the first port of the enthalpy increase electronic expansion valve and the first port of the oil-gas separator through a pipeline, the second port of the enthalpy increase electronic expansion valve is communicated with the second port of the oil-gas separator and the first port of the oil return cooler through a pipeline, the third port of the oil-gas separator is communicated with the second port of the oil return cooler through a pipeline, and the third port of the oil return cooler is communicated with the second port of the compressor through a pipeline; The oil return electronic expansion valve is arranged on a pipeline between the compressor and the oil-gas separator.

2. The air conditioner oil return control system according to claim 1, characterized in that: The oil-gas separator comprises an electric heating component, an oil pool temperature sensor and a control component, wherein the electric heating component and the oil pool temperature sensor are built in a first oil pool cavity in the oil-gas separator; The control component is control-connected to the electric heating component and the oil pool temperature sensor.

3. The air conditioner oil return control system according to claim 1, characterized in that: The control system further comprises a float oil separator, which is arranged on a pipeline between the compressor and the oil-gas separator or the enthalpy-increasing electronic expansion valve; The float oil separator includes an oil return valve and a float, the float is built in the second oil pool cavity of the float oil separator, the oil return valve is arranged at the second port, the first valve port of the oil return valve is connected to the second oil pool cavity, and the second valve port of the oil return valve is connected to the second port.

4. A method for controlling oil return of an air conditioner, characterized in that: The control method is applied to the air-conditioning oil return control system according to any one of claims 1 to 3, and the control method comprises: Obtaining an exhaust superheat value of the compressor, and determining whether the exhaust superheat value satisfies a superheat value condition; If the exhaust gas superheat value satisfies the superheat value condition, controlling the oil-gas separator to adjust to the first superheat value; The opening value of the oil return electronic expansion valve is controlled to be the same as the opening value of the enthalpy increase electronic expansion valve; Obtaining the suction and exhaust temperature values ​​of the compressor, and determining whether the suction and exhaust temperature values ​​of the compressor meet the temperature condition; If the suction and exhaust temperatures of the compressor meet the temperature condition, the compressor is controlled to maintain the current operating state.

5. The air conditioner oil return control method according to claim 4, characterized in that: The obtaining of the exhaust gas superheat value of the compressor comprises: Receive exhaust pressure value and exhaust temperature value sent by the sensor; The exhaust pressure value and the exhaust temperature value are calculated to obtain an exhaust superheat value.

6. The air conditioner oil return control method according to claim 4, characterized in that: After obtaining the exhaust gas superheat value of the compressor and determining whether the exhaust gas superheat value meets the superheat value condition, the method further includes: If the exhaust superheat value does not meet the superheat value condition, the oil-gas separator is controlled to be adjusted to a second superheat value; wherein the superheat value of the first superheat value is lower than the superheat value of the second superheat value.

7. The air conditioner oil return control method according to claim 6, characterized in that: After the oil-gas separator is controlled to be adjusted to the second superheat value, the method further includes: Controlling the heat-increasing electronic expansion valve to enter a closed state so as to set the opening value of the heat-increasing electronic expansion valve to zero; Controlling the oil return electronic expansion valve to enter a fully open operation state to put the compressor into a high-temperature oil return state; Determining whether the exhaust gas superheat value after the compressor in the high-temperature oil return state operates for a first preset time satisfies the superheat value condition; If the exhaust superheat value of the compressor in the high-temperature oil return state does not meet the superheat value condition after operating for the first preset time, the step of controlling the enthalpy-increasing electronic expansion valve to enter the closed state is returned to execution.

8. The air conditioner oil return control method according to claim 4, characterized in that: The opening value of the oil return electronic expansion valve is controlled to be the same as the opening value of the enthalpy increase electronic expansion valve, including: Obtaining the opening value of the enthalpy-increasing electronic expansion valve, and determining whether the opening value of the enthalpy-increasing electronic expansion valve satisfies an opening value condition; If the opening value of the enthalpy-increasing electronic expansion valve satisfies the opening value condition, the opening value of the oil return electronic expansion valve is controlled to be the same as the opening value of the enthalpy-increasing electronic expansion valve; If the opening value of the enthalpy-increasing electronic expansion valve does not satisfy the opening value condition, the enthalpy-increasing pressure value is increased to make the opening value of the oil return electronic expansion valve the same as the opening value of the enthalpy-increasing electronic expansion valve.

9. The air conditioner oil return control method according to claim 8, characterized in that: The step of increasing the enthalpy increase pressure value comprises: receiving a pump cavity pressure value of the compressor sent from a sensor; The oil return electronic expansion valve is controlled to enter an open state to increase the enthalpy increase pressure value to 1.2 to 1.5 times the pump cavity pressure value of the compressor.

10. The air conditioner oil return control method according to claim 4, characterized in that: After obtaining the suction and exhaust temperature value of the compressor and determining whether the suction and exhaust temperature value of the compressor meets the temperature condition, the method further includes: If the suction and exhaust temperature values ​​of the compressor do not meet the temperature condition, the opening value of the enthalpy increase electronic expansion valve and the opening value of the oil return electronic expansion valve are increased to put the compressor into an enthalpy increase pressure state; Determining whether the suction and exhaust temperature value of the compressor in the enthalpy increase pressure state after operating for a second preset time meets the temperature condition; If the suction and exhaust temperature values ​​of the compressor in the enthalpy increase pressure state after operating for the second preset time still do not meet the temperature condition, the step of increasing the opening value of the enthalpy increase electronic expansion valve and the opening value of the oil return electronic expansion valve is returned to execute.

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