Outdoor unit condenser, outdoor unit and variable-frequency air conditioner

Abstract

The present invention relates to the technical field of air conditioning, and particularly to an outdoor unit condenser, an outdoor unit and a variable frequency air conditioner. The present invention aims to solve the problem of low heating efficiency existing in the existing air conditioners. For this purpose, the outdoor unit condenser of the present invention includes a heat exchange tube section, a subcooling tube section, a throttling element, a subcooling connecting tube and a plurality of subcooling valves. The first end of the subcooling tube section can be connected to the indoor unit evaporator through a main capillary tube. The first end and the second end of the subcooling tube section are separated into n subcooling intervals by a plurality of subcooling valves. Each of the plurality of subcooling intervals is connected to the first end of the throttling element through a subcooling connecting tube. The second end of the throttling element is connected to the heat exchange tube section, and the effective length of the subcooling tube section can be adjusted by controlling the opening and closing of each subcooling valve. The above arrangement can improve the heating energy efficiency and inhibit frosting.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and particularly relates to an outdoor unit condenser, an outdoor unit, and a variable frequency air conditioner. Background Art

[0002] Traditional variable frequency air conditioners only evaluate the refrigeration energy efficiency and power, and use the refrigeration energy efficiency as the evaluation standard for the energy efficiency grade, without any requirements for the heating power and capacity. Therefore, when developing variable frequency air conditioners, R & D personnel generally design based on the best refrigeration energy efficiency. However, with the introduction and implementation of the new national energy efficiency standards, the refrigeration and heating power and energy efficiency of variable frequency air conditioners are all included in the assessment scope, and the heating energy efficiency has a great impact on the overall energy efficiency of the air conditioner. Therefore, reducing the heating power of variable frequency air conditioners and improving their heating energy efficiency have become one of the most critical tasks in the industry.

[0003] In addition, during the low-temperature heating process, especially when operating in a low-temperature and high-humidity environment, the frosting speed of the outdoor unit is very fast. As the frost layer thickens, the heating effect deteriorates seriously. Therefore, how to effectively defrost while improving the heating energy efficiency is also one of the difficult problems faced in this field.

[0004] Correspondingly, there is a need in this field for a new outdoor unit condenser, an outdoor unit, and a variable frequency air conditioner to solve the above problems. Summary of the Invention

[0005] In order to solve the above problems in the prior art, that is, to solve the problem of low heating efficiency existing in the existing air conditioners, the present invention provides an outdoor unit condenser. The outdoor unit condenser includes a heat exchange pipe section, a subcooling pipe section, a throttling element, a subcooling connecting pipe, and a plurality of subcooling valves. The first end of the subcooling pipe section can be connected to an indoor unit evaporator through a main capillary tube. The first end and the second end of the subcooling pipe section are separated into n subcooling intervals by the plurality of subcooling valves. A plurality of the subcooling intervals are respectively connected to the first end of the throttling element through a subcooling connecting pipe. The second end of the throttling element is connected to the heat exchange pipe section. The plurality of subcooling valves are configured to be able to adjust the effective length of the subcooling pipe section by controlling the opening and closing of each subcooling valve.

[0006] In a preferred technical solution of the above outdoor unit condenser, the second end of the subcooling pipe section is connected to the heat exchange pipe section. The outdoor unit condenser further includes a confluence connecting pipe and a plurality of confluence valves. A plurality of the subcooling intervals are respectively connected to the second end of the throttling element through a confluence connecting pipe, and each confluence connecting pipe is provided with a confluence valve.

[0007] In the preferred technical solution of the above outdoor unit condenser, the subcooling connecting pipes are provided on the 1st to the (n - 1)th subcooling intervals starting from the first end of the subcooling pipe section, and the converging connecting pipes are provided on the 2nd to the nth subcooling intervals starting from the first end of the subcooling pipe section.

[0008] In the preferred technical solution of the above outdoor unit condenser, the outdoor unit condenser further includes a plurality of on-off valves, and each of the plurality of subcooling connecting pipes is provided with one of the on-off valves.

[0009] In the preferred technical solution of the above outdoor unit condenser, the on-off valve is a one-way valve, and the one-way valve is provided on the 2nd to the (n - 1)th subcooling connecting pipes starting from the first end of the subcooling pipe section; the on-off valve is a solenoid valve, and the solenoid valve is provided on all the subcooling connecting pipes.

[0010] In the preferred technical solution of the above outdoor unit condenser, the outdoor unit condenser further includes a defrosting temperature detection element arranged on the heat exchange pipe section, and the defrosting temperature detection element can be connected to a controller so that the controller adjusts the opening and closing of the plurality of subcooling valves based on the temperature collected by the defrosting temperature detection element.

[0011] In the preferred technical solution of the above outdoor unit condenser, the throttling element is a regulating valve, and the regulating valve is set to open a set opening when the heat exchange medium flows from the indoor unit evaporator to the outdoor unit condenser. The outdoor unit condenser further includes a subcooling temperature detection element arranged on the subcooling pipe section, and the subcooling temperature detection element can be connected to a controller so that the controller adjusts the opening of the regulating valve based on the temperature collected by the subcooling temperature detection element.

[0012] In the preferred technical solution of the above outdoor unit condenser, the subcooling pipe section is arranged on the windward side of the outdoor unit condenser; and / or the subcooling pipe section is arranged below the heat exchange pipe section.

[0013] The present invention also provides an outdoor unit, and the outdoor unit includes the outdoor unit condenser according to any one of the above preferred technical solutions.

[0014] The present invention also provides a variable frequency air conditioner, and the variable frequency air conditioner includes the outdoor unit according to the above preferred technical solution.

[0015] Those skilled in the art can understand that, in the preferred technical scheme of the present invention, the outdoor unit condenser includes a heat exchange pipe section, a subcooling pipe section, a throttling element, a subcooling connecting pipe and a plurality of subcooling valves, the first end of the subcooling pipe section can be connected to the indoor unit evaporator through a main capillary tube, the first end and the second end of the subcooling pipe section are divided into n subcooling intervals by a plurality of subcooling valves, the plurality of subcooling intervals are each connected to the first end of the throttling element through a subcooling connecting pipe, the second end of the throttling element is connected to the heat exchange pipe section, and the plurality of subcooling valves are configured to be able to adjust the effective length of the subcooling pipe section by controlling the opening and closing of each of the subcooling valves.

[0016] By setting a throttling element between the heat exchange pipe section and the subcooling pipe section of the outdoor unit condenser, the air conditioner can make the subcooling pipe section of the outdoor unit condenser serve as an extension and supplement of the indoor unit evaporator when heating, which increases the heat exchange area of the indoor unit evaporator in disguised form, lengthens the subcooling section on the high-pressure side, and further reduces the temperature of the heat exchange medium, reduces the saturation pressure on the high-pressure side, thereby reducing the power of the compressor and greatly reducing the heating energy consumption. After repeated experiments, observations, analyses and comparisons by the inventor, the heating energy efficiency of the air conditioner using the heat exchanger of the present application can be accurately controlled and basically reaches the level of refrigeration energy efficiency when the above-mentioned setting method is adopted.

[0017] The subcooling pipe section is divided into n subcooling intervals by using a plurality of subcooling valves, and the plurality of subcooling intervals are connected to the first end of the throttling element through a subcooling connecting pipe, so that during heating, the effective length of the subcooling pipe section can be adjusted by adjusting the opening and closing of the plurality of subcooling valves, thereby suppressing frost or performing defrosting operation on the outdoor unit condenser through the change of the effective length of the subcooling pipe section, thereby improving the heating efficiency.

[0018] Furthermore, by arranging a defrost temperature detection element on the heat exchange pipe section, the controller can timely and reasonably adjust the opening and closing of several subcooling valves based on the temperature of the heat exchange pipe section, thereby realizing the adjustment of the effective length of the subcooling pipe section, ensuring the heat exchange effect of the superheating pipe section, avoiding frost on the heat exchange pipeline, and improving the heating effect.

[0019] Furthermore, by providing a subcooling temperature detection element on the subcooling pipe section, the opening of the regulating valve can be adjusted based on the temperature of the subcooling pipe section, thereby enabling precise adjustment of the regulating valve during heating, further reducing the power of the compressor and improving heating energy efficiency.

[0020] Furthermore, arranging the subcooled pipe section on the windward side and below the heat exchange pipe section can increase the heat exchange capacity of the heat exchange pipe section on the leeward side, further reduce the compressor power, inhibit frosting or improve the defrosting effect. This is because the temperature of the heat exchange medium in the subcooled pipe section after one throttling is still higher than the ambient temperature. Before the second throttling, through the heat exchange between the subcooled pipe section and the air flow, the heat released by the subcooled pipe section is blown onto the heat exchange pipe section on the leeward side by the air flow for heat exchange. The heat exchange medium in the heat exchange pipe section on the leeward side has reached the low-temperature and low-pressure state after the second throttling, and the heat exchange pipe in the initial section is more likely to frost due to sufficient heat exchange. In this way, it can not only reduce the high-pressure side pressure and thus the compressor power, but also ensure the heat exchange effect of the heat exchange pipe section, achieving the effect of inhibiting frosting when there is no frost and effectively defrosting when there is frost, greatly improving the overall energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The outdoor unit condenser, outdoor unit and variable frequency air conditioner of the present invention will be described below with reference to the accompanying drawings. In the drawings:

[0022] Figure 1 is a system schematic diagram of the variable frequency air conditioner in the first embodiment of the present invention;

[0023] Figure 2 is a system schematic diagram of the variable frequency air conditioner in the second embodiment of the present invention;

[0024] Figure 3 is a partial schematic diagram of the variable frequency air conditioner in the third embodiment of the present invention;

[0025] Figure 4 is a partial schematic diagram of the variable frequency air conditioner in the fourth embodiment of the present invention;

[0026] Figure 5 is a flowchart of the control method of the air conditioner of the present invention;

[0027] Figure 6 is a logic diagram of the control method of the air conditioner of the present invention.

[0028] List of Reference Numerals

[0029] 1. Variable frequency compressor; 2. Four-way valve; 3. Indoor unit evaporator; 4. Indoor fan; 5. Outdoor unit condenser; 51. Heat exchange pipe section; 52. Subcooled pipe section; 53. Throttling element; 54. Subcooled connecting pipe; 55a, 55b, 55c. Subcooling valve; 56. Confluence connecting pipe; 57a, 57b, 57c. Confluence valve; 58a, 58b, 58c. On-off valve; 6. Outdoor fan; 7. Main capillary tube. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention. For example, although the outdoor unit condenser in the drawings is described in combination with a double-row condenser, the specific form of the outdoor unit condenser is not fixed, and those skilled in the art can adjust it according to needs to adapt to specific application scenarios. For example, the present invention can also be applied to a triple-row condenser or a single-row condenser, etc.

[0031] It should be noted that in the description of the present invention, the terms indicating directions or positional relationships such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0032] In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] Example 1

[0034] First, refer to Figure 1 , to describe the variable-frequency air conditioner of the present invention. Among them, Figure 1 is a system schematic diagram of the variable-frequency air conditioner in the first embodiment of the present invention.

[0035] As Figure 1 shown, to solve the problem of poor heating effect of existing air conditioners, the present application provides a variable-frequency air conditioner, which includes an indoor unit, an outdoor unit, and a pipeline connecting the indoor unit and the outdoor unit. Among them, the outdoor unit includes a variable-frequency compressor 1, a four-way valve 2, an outdoor unit condenser 5, an outdoor fan 6, and a main capillary 7, and the indoor unit includes an indoor unit evaporator 3 and an indoor fan 4. Among them, the outdoor unit condenser 5 includes a heat exchange tube section 51, a subcooling tube section 52, a throttling element 53, a subcooling connection tube 54, and a plurality of subcooling valves (55a, 55b). Both the heat exchange tube section 51 and the subcooling tube section 52 are formed by connecting the U-shaped tubes end to end. The first end of the subcooling tube section 52 ( Figure 1The lower end of () is connected to the indoor unit evaporator 3 through the main capillary 7. A plurality of subcooling valves (55a, 55b) are provided on the subcooling pipe section 52 and separate the first end and the second end of the subcooling pipe section 52 ( Figure 1 The upper end of () into n subcooling intervals. A plurality of the subcooling intervals are each connected to the first end of the throttling element 53 through a subcooling connecting pipe 54 ( Figure 1 The right end of ()) is connected, and the second end of the throttling element 53 ( Figure 1 The left end of ()) is connected to the heat exchange pipe section 51. Among them, a plurality of subcooling valves (55a, 55b) are arranged to be able to adjust the effective length of the subcooling pipe section 52 by controlling the opening and closing of each of the subcooling valves (55a, 55b). The throttling element 53 is preferably a regulating valve, which is arranged to be fully open when the heat exchange medium (such as refrigerant, etc.) flows from the outdoor unit condenser 5 to the indoor unit evaporator 3, and to open a set opening when the heat exchange medium flows from the indoor unit evaporator 3 to the outdoor unit condenser 5.

[0036] It should be explained that in this application, the effective length refers to the length of the part of the subcooling pipe section 52 that has a subcooling effect. This length can be controlled by controlling the opening and closing of the subcooling valves (55a, 55b). The longest effective length is the full length of the subcooling pipe section 52. The set opening refers to any opening between fully closed and fully open, and the specific size of the opening can be controlled based on parameters, such as being controlled based on parameters such as the outdoor ambient temperature and the temperature of the subcooling pipe section 52, etc.

[0037] Referring to Figure 1 , taking the heat exchange medium as refrigerant as an example, when the variable-frequency air conditioner operates in the cooling mode, the regulating valve is fully open. After the refrigerant is discharged from the exhaust port of the variable-frequency compressor 1, it enters the outdoor unit condenser 5 and sequentially flows through the heat exchange pipe section 51, the regulating valve, the subcooling connecting pipe 54 and the subcooling pipe section 52 to perform condensation heat exchange with the outdoor air. The heat-exchanged refrigerant enters the indoor unit evaporator 3 after throttling by the main capillary 7 to perform evaporation heat exchange with the indoor air. The heat-exchanged refrigerant returns to the variable-frequency compressor 1 from the suction port of the variable-frequency compressor 1 to complete a refrigeration cycle. When the variable-frequency air conditioner operates in the heating mode, the regulating valve opens a set opening, and the subcooling valves (55a, 55b) open and close according to the set control method to adjust the effective length of the subcooling pipe section 52. After the refrigerant is discharged from the exhaust port of the variable-frequency compressor 1, it first enters the indoor unit evaporator 3 to perform condensation heat exchange with the indoor air. The heat-exchanged refrigerant enters the subcooling pipe section 52 after the first throttling and temperature reduction by the main capillary 7. The temperature of the refrigerant entering the subcooling pipe section 52 is still relatively high. At this time, the refrigerant in the effective length part of the subcooling pipe section 52 performs further condensation heat exchange with the outdoor air, then flows through the subcooling connecting pipe 54 and enters the regulating valve, and enters the heat exchange pipe section 51 after the secondary throttling of the regulating valve to perform evaporation heat exchange with the outdoor air. The heat-exchanged refrigerant returns to the variable-frequency compressor 1 from the suction port of the variable-frequency compressor 1 to complete a heating cycle.

[0038] From the above description, it can be seen that by setting a regulating valve between the heat exchange pipe section 51 and the subcooling pipe section 52 of the outdoor unit condenser 5, the variable frequency air conditioner can avoid the influence of the regulating valve on the refrigeration energy efficiency by fully opening the regulating valve when cooling, and realize the normal frequency regulation of the air conditioner; when heating, by controlling the opening change of the regulating valve, the supercooling degree can be accurately controlled, so that the subcooling pipe section 52 of the outdoor unit condenser 5 acts as an extension and supplement of the indoor unit evaporator 3, which increases the heat exchange area of the indoor unit evaporator 3 in disguised form, lengthens the subcooling section on the high-pressure side, and further reduces the temperature of the heat exchange medium, reduces the saturation pressure on the high-pressure side, thereby reducing the power of the compressor and greatly reducing the heating energy consumption. After repeated experiments, observations, analyses and comparisons by the inventor, the heating energy efficiency of the air conditioner using the heat exchanger of the present application can be accurately controlled and basically reaches the level of refrigeration energy efficiency when the above-mentioned setting method is adopted.

[0039] Furthermore, the subcooling pipe section 52 is divided into n subcooling intervals by using a plurality of subcooling valves (55a, 55b), and the plurality of subcooling intervals are connected to the first end of the regulating valve via a subcooling connecting pipe 54, so that during heating, the effective length of the subcooling pipe section 52 can be adjusted by adjusting the opening and closing of the plurality of subcooling valves (55a, 55b), thereby suppressing frost or performing defrosting operation on the outdoor unit condenser 5 through the change in the effective length of the subcooling pipe section 52, thereby improving the heating efficiency.

[0040] It should be noted that, although the throttling element 53 is described as a regulating valve in this embodiment, this is not intended to limit the scope of protection of the present application. In other application scenarios, technical personnel in this field may replace the regulating valve with other throttling elements 53, such as replacing the regulating valve with a capillary tube, or a one-way valve may be connected in parallel to the capillary tube so as not to affect the refrigeration effect. The one-way valve is set to be turned on when the air conditioner runs in cooling mode and turned off when running in heating mode.

[0041] See below for further reference Figure 1 , and in combination with the two supercooling valves ( 55a , 55b ) provided on the supercooling pipe section 52 , the first embodiment of the variable frequency air conditioner of the present application is described in detail.

[0042] like Figure 1As shown, in a more preferred embodiment, two subcooling valves (55a, 55b) divide the subcooling pipe section 52 into three subcooling intervals, and each of the three subcooling intervals is connected to the first end of the regulating valve through a subcooling connecting pipe 54. Among them, an on-off valve (58a, 58b, 58c) is also provided on each subcooling connecting pipe 54. By controlling the opening and closing of the subcooling valves (55a, 55b) and the on-off valves (58a, 58b, 58c), the effective length of the subcooling pipe section 52 can be controlled. For example, when the subcooling valve 55a is closed, the on-off valve 58a is opened, and 58b and 58c are closed, the effective length of the subcooling pipe section 52 is the length of the first subcooling interval near the first end ( Figure 1 the lower end in) of the subcooling pipe section 52; when the subcooling valve 55a is opened, 55b is closed, the on-off valve 58b is opened, and 58a and 58c are closed, the effective length of the subcooling pipe section 52 is the sum of the lengths of the first subcooling interval and the second subcooling interval starting from the first end of the subcooling pipe section 52, and so on. Among them, the subcooling valves (55a, 55b) and the on-off valves (58a, 58b, 58c) can be electrically controlled valves such as solenoid valves and electronic expansion valves.

[0043] Through the setting of the subcooling valves (55a, 55b) and the on-off valves (55a, 55b), during heating, the effective length of the subcooling pipe section 52 can be adjusted by adjusting the opening and closing of the subcooling valves (55a, 55b) and the on-off valves, so as to suppress frosting or defrost the outdoor unit condenser 5 by changing the effective length of the subcooling pipe section 52, and improve the heating efficiency.

[0044] Continue to refer to Figure 1 , in a more preferred embodiment, the outdoor unit condenser 5 is a double-row heat exchanger, and the subcooling pipe section 52 is arranged below the heat exchange pipe section 51 and on the windward side of the outdoor unit condenser 5 (i.e., Figure 1 the right side in).

[0045] By arranging the subcooling pipe section 52 on the windward side and below the heat exchange pipe section 51, the heat exchange capacity of the heat exchange pipe section 51 on the leeward side can be increased, the compressor power can be further reduced, frosting can be suppressed or the defrosting effect can be improved. This is because, generally, the temperature of the heat exchange medium in the subcooling section after one throttling is still higher than the ambient temperature. Before the second throttling, through the heat exchange between the subcooling pipe section 52 and the air flow, the heat released by the subcooling pipe section 52 is blown onto the heat exchange pipe section 51 on the leeward side by the air flow for heat exchange. The heat exchange medium in the heat exchange pipe section 51 on the leeward side has reached a low-temperature and low-pressure state after the second throttling, and the heat exchange pipe in the initial section is more likely to frost due to sufficient heat exchange. In this way, both the high-pressure side pressure can be reduced to reduce the compressor power, and the heat exchange effect of the heat exchange pipe section 51 can be ensured, achieving the effect of suppressing frosting when there is no frost and effectively defrosting when there is frost, so that the overall energy efficiency is greatly improved.

[0046] Still referring to Figure 1 In a more preferred embodiment, the outdoor unit condenser 5 further includes a defrosting temperature detection element (not shown in the figure), which is arranged on the heat exchange pipe section 51, preferably at the initial section of the heat exchange pipe section 51. The defrosting temperature detection element can be connected to the controller of the variable frequency air conditioner, so that the controller can control the opening and closing of the subcooling valves (55a, 55b) based on the temperature of the heat exchange pipe section 51 collected by the defrosting temperature detection element during the heating operation, that is, adjust the effective length of the subcooling pipe section 52. Among them, the defrosting temperature detection element can be a temperature sensor, a temperature sensing bulb, etc., which is attached to the outer surface of the U-shaped pipe at the initial section of the heat exchange pipe section 51 and is connected to the controller through a lead wire. Among them, the controller can be the controller of the air conditioner.

[0047] By arranging the defrosting temperature detection element at the initial section of the heat exchange pipe section 51, the controller can timely and reasonably adjust the opening and closing of the subcooling valves (55a, 55b) and the on-off valves (58a, 58b, 58c) based on the temperature of the heat exchange pipe section 51, so as to adjust the effective length of the subcooling pipe section 52, ensure the heat exchange effect of the superheat pipe section, inhibit frosting of the heat exchange pipeline, and improve the heating effect.

[0048] Continue to refer to Figure 1 In a more preferred embodiment, the outdoor unit condenser 5 further includes a subcooling temperature detection element (not shown in the figure), which is arranged on the subcooling pipe section 52 and can be connected to the controller of the variable frequency air conditioner, so that the controller can control the opening degree of the regulating valve based on the temperature of the subcooling pipe section 52 collected by the subcooling temperature detection element during the heating operation. Among them, the subcooling temperature detection element can be a temperature sensor, a temperature sensing bulb, etc., which is attached to the outer surface of the U-shaped pipe of the subcooling pipe section 52 and is connected to the controller through a lead wire. Among them, the controller can be the controller of the air conditioner or a PID regulator, etc.

[0049] By arranging the subcooling temperature detection element on the subcooling pipe section 52, the opening degree of the regulating valve can be adjusted based on the temperature of the subcooling pipe section 52, and thus the accurate adjustment of the regulating valve can be realized during heating, reducing the power of the compressor and improving the heating energy efficiency.

[0050] Continue to refer to Figure 1, in a more preferred embodiment, the heat exchange tube section 51 is divided into multiple flow paths, and the cross-section of the flow path is n-shaped and / or N-shaped. Specifically, in this embodiment, the heat exchange tube section 51 has two flow paths. The cross-sections of the two flow paths are one n-shaped and one N-shaped, and the flow directions are both from the windward side to the leeward side. In this way, by dividing the heat exchange tube section 51 into multiple flow paths, the refrigerant undergoes heat exchange simultaneously in multiple paths during the heat exchange process, ensuring the heat exchange efficiency and effect. By setting the flow directions of the two flow paths to both flow from the windward side to the leeward side, the temperature of the air flow after heat exchange with the refrigerant on the windward side increases during the flow of the refrigerant, and then it undergoes heat exchange with the refrigerant on the leeward side, improving the heat exchange effect of the heat exchange tube section 51 and also suppressing frosting.

[0051] Of course, those skilled in the art can understand that the above setting method is not fixed. Without departing from the principle of this application, those skilled in the art can adjust it as long as the adjustment satisfies dividing the heat exchange tube section 51 into multiple flow paths, and the cross-section of each flow path is n-shaped and / or N-shaped. For example, the flow path can also be divided into three or more, and the cross-section of each flow path is N-shaped or n-shaped, etc.

[0052] In a more preferred embodiment, the regulating valve is an electronic expansion valve in this embodiment. The regulating valve is set to be fully open when the variable-frequency air conditioner operates in the cooling mode and to open a set opening when operating in the heating mode. The setting of the regulating valve enables the variable-frequency air conditioner to accurately regulate the subcooling degree of the system by adjusting the opening of the electronic expansion valve during the heating process, thereby reducing the heating power and improving the heating energy efficiency.

[0053] Although the electronic expansion valve is used as the regulating valve in this embodiment, this is not restrictive. Those skilled in the art can change it based on the specific application scenario. For example, the regulating valve can also use an electromagnetic valve or other electronically controlled valves.

[0054] Next, refer to Figure 2 , and in combination with the setting of three subcooling valves (55a, 55b, 55c) on the subcooling tube section 52, the second embodiment of the variable-frequency air conditioner of this application will be described.

[0055] As Figure 2As shown, in a more preferred embodiment, three subcooling valves (55a, 55b, 55c) divide the subcooling pipe section 52 into four subcooling intervals. The first to the third subcooling intervals from bottom to top in the four subcooling intervals are each connected to the first end of the regulating valve through a subcooling connecting pipe 54. Among them, an on-off valve (58a, 58b, 58c) is also provided on each subcooling connecting pipe 54. By controlling the opening and closing of the subcooling valves (55a, 55b, 55c) and the on-off valves (58a, 58b, 58c), the effective length of the subcooling pipe section 52 can be controlled. In particular, the second end of the subcooling pipe section 52 is also connected to the heat exchange pipe section 51. The outdoor unit condenser 5 also includes three converging connecting pipes 56 and three converging valves (57a, 57b, 57c). The second to the fourth subcooling intervals from bottom to top in the four subcooling intervals are each connected to the second end of the regulating valve through a converging connecting pipe 56, and a converging valve is also provided on each converging connecting pipe 56. In this way, during the heating process, by jointly controlling the subcooling valves (55a, 55b, 55c), the converging valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c), the effective length of the subcooling pipe section 52 can be adjusted, and the remaining pipeline outside the effective length of the subcooling pipe section 52 is diverted through the converging connecting pipe 56 and the converging valve to participate in evaporation heat exchange in the heat exchange pipeline.

[0056] For example, when the subcooling valve 55a is closed, 55b and 55c are opened, the on-off valve 58a is opened, 58b and 58c are closed, and the converging valve 57a is opened, 57b and 57c are closed, the effective length of the subcooling pipe section 52 is the length of the first subcooling interval near the first end ( Figure 1 the lower end in) of the subcooling pipe section 52, while the second subcooling interval and the fourth subcooling interval are connected to the heat exchange pipe section 51, and part of the refrigerant flowing out from the second end of the regulating valve flows through the converging valve 57a and flows through the second to the fourth subcooling intervals in sequence and into the heat exchange pipe section 51; when the subcooling valve 55b is closed, 55a and 55c are opened, the on-off valve 58b is opened, the on-off valve 58a and 58c are closed, and the converging valve 55b is opened, 55a and 55c are closed, the effective length of the subcooling pipe section 52 is the sum of the lengths of the first and second subcooling intervals starting from the first end of the subcooling pipe section 52, and the third and fourth subcooling intervals are connected to the heat exchange pipe section 51, and so on. Among them, the subcooling valves (55a, 55b, 55c), the converging valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c) can also be electrically controlled valves such as solenoid valves and electronic expansion valves.

[0057] By providing the subcooling valves (55a, 55b, 55c), the confluence valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c), during heating, the effective lengths of the subcooling pipe section 52 and part of the heat exchange pipe section 51 can be skillfully adjusted by jointly regulating the opening and closing of the subcooling valves, the confluence valves and the on-off valves. Thus, by changing the effective length of the subcooling pipe section 52, frosting can be inhibited or defrosting operation can be performed on the outdoor unit condenser 5, the heating efficiency can be improved, and the remaining pipeline of the subcooling pipe section 52 can be reasonably utilized to supplement the heat exchange pipe section 51, thereby improving the evaporation heat exchange effect of the heat exchange pipe section 51.

[0058] Certainly, those skilled in the art can understand that in the first and second embodiments, the number and arrangement of the subcooling valves (55a, 55b, 55c), the confluence valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c) are not restrictive. Without departing from the principle of this application, those skilled in the art can make adjustments to the above methods so that this application can be applied to more specific application scenarios.

[0059] For example, although the above-mentioned first and second embodiments are described in combination with the setting of two subcooling valves and three subcooling valves (55a, 55b, 55c), obviously the number of subcooling valves is not limited to this. Those skilled in the art can reasonably adjust its number. For example, the subcooling valve can also be set to one, four or more. Similarly, the numbers of the confluence valves and the on-off valves can also be adjusted as long as the adjustment conforms to the principle of this application, which will not be elaborated here.

[0060] Again, Figure 3 and Figure 4 respectively show partial schematic diagrams of the third and fourth embodiments of the variable-frequency air conditioner of this application. As Figure 3 shown, those skilled in the art can also, on the basis of the first or second embodiment, omit the setting of the on-off valves (58a, 58b, 58c), and instead effectively guide the refrigerant by reasonably setting the curvature of the subcooling connection pipe 54 to prevent the refrigerant from flowing back during the refrigeration or heating process. As Figure 4 shown, those skilled in the art can also, on the basis of the first or second embodiment, replace the on-off valves (58a, 58b, 58c) with check valves and only set them on part of the subcooling pipelines to prevent the phenomenon of refrigerant flowing back during the heating process.

[0061] Of course, the above various replaceable embodiments, as well as between the replaceable embodiments and the preferred embodiments, can also be used in cross-combination, so as to combine new embodiments to be applicable to more specific application scenarios. For example, combining the third embodiment and the fourth embodiment, on the basis of reasonably setting the radian of the subcooling connecting pipe 54, a check valve is added to a part of the subcooling connecting pipe 54.

[0062] The following will briefly describe Figure 2 the working process of the variable-frequency air conditioner of the present invention.

[0063] As Figure 2 shown, when the variable-frequency air conditioner operates in the cooling mode, the regulating valve is fully open, all the subcooling valves (55a, 55b, 55c) are fully open, all the confluence valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c) are fully closed. After the refrigerant is discharged from the exhaust port of the variable-frequency compressor 1, it enters the outdoor unit condenser 5 and simultaneously flows through the n-type flow path and the N-type flow path of the heat exchange pipe section 51 to exchange heat with the outdoor air for condensation, and then converges into one flow path after the regulating valve. Then, the refrigerant enters the indoor unit evaporator 3 through the throttling of the main capillary 7 to exchange heat with the indoor air. After heat exchange, the refrigerant returns to the variable-frequency compressor 1 from the suction port of the variable-frequency compressor 1 to complete a refrigeration cycle.

[0064] When the variable-frequency air conditioner operates in the heating mode, the regulating valve is opened to a set opening degree, the subcooling valves 55a are closed, 55b and 55c are opened, the on-off valves 58a are opened, 58b and 58c are closed, the converging valves 57a are opened, 57b and 57c are closed. After the refrigerant is discharged from the exhaust port of the variable-frequency compressor 1, it first enters the indoor unit evaporator 3 to perform condensation heat exchange with the indoor air. The heat-exchanged refrigerant undergoes the first throttling and temperature reduction through the main capillary tube 7, and then enters the first subcooling interval of the subcooling pipe section 52 of the outdoor unit condenser 5. The temperature of the refrigerant entering the first subcooling interval is still relatively high. At this time, after further condensation heat exchange with the outdoor air, under the secondary throttling of the regulating valve, part of the refrigerant passes through the I-shaped heat exchange pipe section 51 and the converging connection pipe 56 after the regulating valve and then enters the second to fourth subcooling intervals of the subcooling pipe section 52, and then enters the N-shaped flow path of the heat exchange pipe section 51 to perform evaporation heat exchange with the outdoor air. Another part of the refrigerant passes through the I-shaped heat exchange pipe section 51 after the regulating valve and enters the n-shaped flow path of the heat exchange pipe section 51 to perform evaporation heat exchange with the outdoor air. After the heat-exchanged refrigerants converge into one flow path, they return to the variable-frequency compressor 1 from the suction port of the variable-frequency compressor 1 to complete a heating cycle. Among them, during the heat exchange process, the temperature of the air flow after heat exchange with the subcooling pipe section 52 and the windward-side heat exchange pipe section 51 increases, and then heat exchange is performed with the I-shaped heat exchange pipe section 51 on the leeward side to inhibit frosting. If it is determined through the temperature acquisition of the frost formation temperature detection element that the I-shaped heat exchange pipe section 51 frosts during the heating process, then the opening and closing of the subcooling valves (55a, 55b, 55c), the converging valves (57a, 57b, 57c), and the on-off valves (58a, 58b, 58c) are reasonably controlled to change the effective length of the subcooling pipe section 52 and the effective length of part of the heat exchange pipe section 51, and rapid defrosting is achieved by increasing the effective length of the subcooling pipe section 52.

[0065] Of course, those skilled in the art can also change the above control process. For example, during the refrigeration operation, it is also possible to achieve the purpose of converging the refrigerant into one path before the regulating valve and further subcooling it through part of the subcooling pipe section by closing the subcooling valve 55a, opening 55b and 55c, opening the on-off valve 58a, closing 58b and 58c, and opening the converging valve 57a, closing 57b and 57c.

[0066] Those skilled in the art can understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of the present invention and forms different embodiments. For example, in the claims of the present invention, any one of the claimed embodiments can be used in any combination.

[0067] Example 2

[0068] Refer to the following Figure 2 andFigure 5 , the heating control method of the air conditioner of the present application will be introduced. Among them, Figure 5 is the flow chart of the control method of the air conditioner of the present invention.

[0069] As Figure 2 and Figure 5 shown, corresponding to the above-mentioned variable-frequency air conditioner, the present application also provides a control method for a variable-frequency air conditioner. The specific structure of the variable-frequency air conditioner has been introduced in Embodiment 1 and will not be elaborated here. The control method includes:

[0070] S100. When operating in heating mode, obtain the outdoor ambient temperature; for example, when the air conditioner is operating in heating mode, obtain the outdoor ambient temperature through the temperature sensor set on the outdoor unit.

[0071] S200. Compare the size of the outdoor ambient temperature with the temperature threshold; for example, the temperature threshold is the temperature that can reflect whether the outdoor unit is prone to frosting. For example, the temperature threshold is 5°C. After obtaining the outdoor ambient temperature, compare the outdoor ambient temperature with 5°C. Of course, the above temperature threshold is only an example. Those skilled in the art can adjust it based on the specific application scenario, such as adjusting it based on test or empirical values, as long as the temperature value can be used as the critical value reflecting whether the outdoor unit is prone to frosting.

[0072] S300. When the outdoor ambient temperature is lower than the temperature threshold, obtain the temperature of the heat exchange pipe section 51; for example, still taking the temperature threshold of 5°C as an example, when the outdoor ambient temperature is lower than 5°C, it proves that the outdoor unit is prone to frosting at this time. At this time, it is necessary to obtain the temperature of the heat exchange pipe section 51 for further analysis to determine whether the heat exchange pipe section 51 has frosted.

[0073] S400. Based on the temperature of the heat exchange pipe section 51, selectively adjust the opening and closing of several sub-cooling valves (55a, 55b, 55c) to adjust the effective length of the sub-cooling pipe section 52; for example, when the temperature of the heat exchange pipe section 51 continues to be lower than a certain temperature value, it proves that the heat exchange pipe section 51 has frosted. At this time, it is necessary to adjust the opening and closing of several sub-cooling valves (55a, 55b, 55c) to adjust the effective length of the sub-cooling pipe section 52, that is, to adjust the number of sub-cooling intervals that play a sub-cooling role in the sub-cooling pipe section 52, so as to improve the defrosting ability of the outdoor unit condenser 5 and defrost the outdoor unit condenser 5 in time. Among them, the method of adjusting the effective length of the sub-cooling pipe section 52 has been introduced in Embodiment 1 and will not be elaborated here.

[0074] By selectively adjusting the opening and closing of the subcooling valves (55a, 55b, 55c) according to the temperature of the heat exchange pipe section 51 when the outdoor ambient temperature is lower than the temperature threshold, so as to adjust the effective length of the subcooling pipe section 52, the control method of the present application can effectively improve the heating effect of the air conditioner, improve the heating energy efficiency of the air conditioner, inhibit frosting and effectively defrost. Specifically, usually when the outdoor ambient temperature is lower than the temperature threshold, especially in a low-temperature and high-humidity outdoor environment, the outdoor unit condenser 5 of the air conditioner is extremely likely to frost during the heating operation. After frosting, it will seriously affect the heating efficiency of the air conditioner and reduce the heating energy efficiency. In the present application, a throttling element 53 is provided between the heat exchange pipe section 51 and the subcooling pipe section 52, and several subcooling valves (55a, 55b, 55c) are used to divide the subcooling pipe section 52 into multiple subcooling intervals. In this way, through the secondary throttling of the throttling element 53, the outdoor subcooling pipe section 52 can perform condensation heat exchange as a supplement to the indoor evaporator during the heating process, so that the hot air flow after the condensation heat exchange can exchange heat with the heat exchange pipe section 51 again, which can not only inhibit the frosting of the heat exchange pipe section 51, but also defrost in time when the heat exchange pipe section 51 frosts. On this basis, by controlling the opening and closing of different subcooling valves (55a, 55b, 55c), the number of subcooling intervals that play a subcooling role in the subcooling pipe section 52 can be controlled, the effective length of the subcooling pipe section 52 can be adjusted, and further the frosting degree and defrosting effect can be controlled.

[0075] It should be noted that although the above-mentioned embodiment determines that the heat exchange pipe section 51 frosts when the outdoor ambient temperature is lower than the temperature threshold, this is not the only condition for judging frosting or not. Those skilled in the art can understand that other judgment conditions can also be added to jointly judge whether the subcooling pipe section 52 frosts. For example, on the basis of temperature judgment, humidity judgment is added. When both the temperature and humidity are lower than a certain threshold, it is determined that the subcooling pipe section 52 frosts.

[0076] The control method of the present application will be introduced in detail below.

[0077] In a preferred embodiment, before step S400, the control method of the air conditioner further includes: adjusting the opening and closing of several subcooling valves (55a, 55b, 55c) to make the effective length of the subcooling pipe section 52 the shortest. Specifically, the effective length of the subcooling pipe section 52 can be controlled to be the shortest when entering the heating mode, or when it is determined that the outdoor ambient temperature is lower than the temperature threshold or any other timing prior to collecting the temperature of the heat exchange pipe section 51. For example, referring to Figure 2For the illustrated embodiment, controlling the effective length of the subcooling pipe section 52 to be the shortest means controlling the minimum number of subcooling intervals in the subcooling pipe section 52 that can perform the subcooling function. That is, by controlling the subcooling valve 55a to be closed and 55b and 55c to be opened, the converging valve 57a to be opened and 57b and 57c to be closed, and the on-off valve 58a to be opened and 58b and 58c to be closed. At this time, the effective length of the subcooling pipe section 52 is the length of the first subcooling interval starting from the first end ( Figure 2 the illustrated lower end) of the subcooling pipe section 52.

[0078] In a preferred embodiment, step S400 may further include: every set time period, obtaining and recording the temperature of the heat exchange pipe section 51 within the set time period; calculating the temperature change rate of the heat exchange pipe section 51 within the set time period based on the temperature and the set time period; comparing the magnitude of the temperature change rate with a set threshold; when the temperature change rate is greater than the set threshold and lasts for a preset time, adjusting the opening and closing of several subcooling valves (55a, 55b, 55c) to increase the effective length of the subcooling pipe section 52 until the effective length of the subcooling pipe section 52 increases to the longest; simultaneously with, before, or after adjusting the opening and closing of several subcooling valves (55a, 55b, 55c), adjusting the opening and closing of several converging valves (57a, 57b, 57c) so that the part outside the effective length is communicated with the heat exchange pipe section 51; and simultaneously with, before, or after adjusting the opening and closing of several subcooling valves (55a, 55b, 55c), adjusting the opening and closing of several on-off valves (58a, 58b, 58c) to cut off the communication between the part outside the effective length and the effective length.

[0079] Specifically, the set time period can be any value between 2 min and 5 min, or it can be other values. After obtaining and recording the temperature of the heat exchange pipe section 51 within the set time period, the temperature change rate of the heat exchange pipe section 51 within the set time period can be calculated based on the following formula (1):

[0080]

[0081] In formula (1), K is the temperature change rate of the heat exchange pipe section 51 within the set time period; T n is the temperature at the nth sampling point within the set time period, T n-1 is the temperature at the (n - 1)th sampling point within the set time period, and t is the time interval between the nth sampling point and the (n - 1)th sampling point.

[0082] When the calculated temperature change rate is less than or equal to a certain set threshold and lasts for a preset time, for example, the set threshold is -1 and the preset time is 1 min. When K ≤ -1 and lasts for 1 min, it proves that the heat exchange pipe section 51 is frosting rapidly at this time, resulting in a continuous decrease in the coil temperature. Moreover, the heat flow brought by the effective length of the current subcooled pipe section 52 is insufficient to defrost the heat exchange pipe section 51, and the defrosting ability needs to be improved. At this time, by adjusting the opening and closing of the subcooling valves (55a, 55b, 55c), the confluence valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c), the effective length of the subcooled pipe section 52 can be increased, the heat exchange length of the subcooled pipe section 52 can be improved, thereby improving the defrosting ability, and at the same time, the part outside the effective length is connected to the heat exchange pipe section 51. For example, still taking the Figure 2 shown air conditioner as an example, when the effective length of the subcooled pipe section 52 is the shortest, by controlling the subcooling valve 55b to close, 55a and 55c to open, the confluence valve 57b to open, 57a and 57c to close, and the on-off valve 58b to open, 58a and 58c to close, the effective length of the subcooled pipe section 52 is increased to the sum of the lengths of the first subcooling interval and the second subcooling interval starting from the first end of the subcooled pipe section 52, and the third to fourth subcooling intervals are connected to the heat exchange pipe section 51, and the connection between the third to fourth subcooling intervals and the first to second subcooling intervals is cut off. And so on, until the effective length of the subcooled pipe section 52 increases to the maximum. On the contrary, when the calculated temperature change rate K > -1 or the time when K ≤ -1 does not last for 1 min, it proves that the heat exchange pipe section 51 is not frosting or the frosting is not serious at this time, and its heat exchange effect is good. Therefore, there is no need to adjust the subcooling valves (55a, 55b, 55c), and only need to control the subcooling valves (55a, 55b, 55c) to maintain the current state.

[0083] By adjusting the effective length of the subcooled pipe section 52 based on the temperature change rate at each set time period, the control method of the present application can also adjust the defrosting ability accordingly based on the frosting condition of the current heat exchange pipe section 51, improve the defrosting effect, avoid the situation where the defrosting ability does not match the frosting degree, and ensure the heating efficiency. By adjusting the opening and closing of the confluence valves (57a, 57b, 57c) simultaneously with, before or after adjusting the opening and closing of the subcooling valves (55a, 55b, 55c) so that the part outside the effective length is connected to the heat exchange pipe section 51, the control method of the present application can also reasonably utilize the part outside the effective length as a supplement to the heat exchange pipe section 51 to improve the evaporation heat exchange effect. By adjusting the opening and closing of the on-off valves (58a, 58b, 58c) simultaneously with, before or after adjusting the opening and closing of the subcooling valves (55a, 55b, 55c) to cut off the connection between the part outside the effective length and the effective length, the control method of the present application can also improve the utilization rate of the refrigerant in the subcooled pipe section 52 and ensure the heat exchange efficiency.

[0084] Of course, the above embodiments are introduced in combination with Figure 2 the air conditioner shown. Those skilled in the art can understand that when the setting mode of the air conditioner is in other forms, the above embodiments can be adjusted accordingly, and some steps can be appropriately added or deleted so that the control method of the present application can have better applicability. For example, when the air conditioner is in the setting mode as Figure 1 shown, the step of adjusting the opening and closing of the manifold valve can be omitted; when the air conditioner is in the setting mode as Figure 3 or Figure 4 shown, the step of adjusting the opening and closing of the on-off valves (58a, 58b, 58c) can be omitted; when only the subcooling valves (55a, 55b, 55c) are provided in the air conditioner, the steps of adjusting the opening and closing of the manifold valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c) can be omitted simultaneously, etc.

[0085] Furthermore, in addition to the method of comparing the temperature change rate with the set threshold, other methods can also be used to obtain the conclusion of whether the superheat pipe section is frosted. These methods do not deviate from the principle of the present application, so they should reasonably fall within the protection scope of the present application. For example, the method of rounding down the temperature change rate K and determining whether the result is less than the set threshold, that is, determining whether Int(K) is less than the set threshold (such as whether it is less than 0), can also be used to determine whether the heat exchange pipe section 51 is frosted, or by integrating the temperature change amount within a set time period and calculating the magnitude of the integration result and the set value to determine whether the heat exchange pipe section 51 is frosted, etc.

[0086] In a preferred embodiment, when the throttling element 53 is a regulating valve with a controllable opening, such as a solenoid valve or an electronic expansion valve, etc., the control method of the air conditioner further includes: during heating operation, determining the operating opening of the regulating valve; adjusting the opening of the regulating valve to the operating opening. Specifically, obtaining the outdoor ambient temperature and the operating frequency of the compressor; calculating the theoretical temperature of the subcooling pipe section 52 based on the outdoor ambient temperature; calculating the operating opening of the regulating valve based on the outdoor ambient temperature, the operating frequency, and the theoretical temperature; adjusting the opening of the regulating valve to the operating opening. It should be noted that the above steps can be carried out after adjusting the opening and closing of the subcooling valves (55a, 55b, 55c), the manifold valves (57a, 57b, 57c), and the on-off valves (58a, 58b, 58c), or can also be run before or after other steps. The change of the operating timing does not deviate from the protection scope of the present application.

[0087] For example, the outdoor ambient temperature can be obtained through a temperature sensor provided on the outdoor unit, and the operating frequency of the compressor can be obtained based on the operating parameters during the operation of the variable-frequency air conditioner, and then the following formula (2) is used to calculate the theoretical temperature of the subcooling pipe section 52:

[0088] T c = k × T ao + p (2)

[0089] In formula (2), T c is the theoretical temperature of the subcooling pipe section 52; T ao is the outdoor ambient temperature; k and p are constants, and these constants can be obtained by fitting based on experimental data. For example, the air conditioner is experimented multiple times for different outdoor ambient temperatures. In the experiment, based on different outdoor ambient temperatures, by adjusting the temperature of the subcooling pipe section 52, the heat transfer effect under this condition is optimized, and the temperature of the subcooling pipe section 52 when the heat transfer effect is optimal is recorded as the theoretical temperature under this condition. After multiple tests, the values of the constants k and p are calculated using the method of linear fitting, so as to obtain the fitting formula between the outdoor ambient temperature and the theoretical temperature of the subcooling pipe section 52.

[0090] Those skilled in the art can understand that the theoretical temperature of the subcooling pipe section 52 determines the heat transfer effect and defrosting effect of the subcooling pipe section 52, indirectly determines the heating energy efficiency, and the heat transfer effect of the subcooling pipe section 52 is directly related to the outdoor ambient temperature. When the temperature difference between the outdoor ambient temperature and the subcooling pipe section 52 reaches a certain range, the subcooling degree of the air conditioning system also reaches a better state. By calculating the theoretical temperature of the subcooling pipe section 52 based on the outdoor ambient temperature, the control method of the present application can associate the theoretical temperature of the subcooling pipe section 52 with the outdoor ambient temperature, and on the basis of ensuring the best subcooling degree and subcooling effect of the outdoor heat exchanger, reduce the power of the compressor and improve the heating efficiency.

[0091] Of course, the determination of the theoretical temperature is not limited to the method shown in formula (2) above. Under the condition of not deviating from the principle of the present application, any method of determining the theoretical temperature of the subcooling pipe section 52 through the outdoor ambient temperature can replace formula (2). For example, the specific value of the theoretical temperature can also be determined through the corresponding relationship between the outdoor ambient temperature and the theoretical temperature of the subcooling pipe section 52.

[0092] In a more preferred embodiment, taking the regulating valve as an electronic expansion valve as an example, the following fitting formula (3) can be used to calculate the operating opening of the electronic expansion valve:

[0093] B = a × f + b × T ao + c × Int(T c - T ao ) (3)

[0094] In formula (3), B is the operating opening of the electronic expansion valve; f is the operating frequency of the compressor; T c is the theoretical temperature of the subcooling pipe section 52; T ao is the outdoor ambient temperature; Int(Tc -T ao ) is to round the difference between the theoretical temperature of the subcooled pipe section 52 and the outdoor ambient temperature; a, b, and c are constants, which can be obtained by fitting based on experimental data. For example, multiple experiments are conducted on the heating energy efficiency of the air conditioner for different outdoor ambient temperatures, compressor frequencies, and theoretical temperatures of the subcooled pipe section 52. In the experiment, the opening degree of the electronic expansion valve is adjusted to minimize the heating energy efficiency of the air conditioner, and the opening degree parameter of the electronic expansion valve corresponding to the current heating energy efficiency is recorded as the operating opening degree of the electronic expansion valve under this condition. After multiple tests, the values of the constants a, b, and c are calculated, so as to obtain the fitting formula between the electronic expansion valve and the outdoor ambient temperature, compressor frequency, and theoretical temperature of the subcooled pipe section 52.

[0095] By jointly determining the operating opening degree of the electronic expansion valve based on the operating frequency of the compressor, the theoretical temperature of the subcooled pipe section 52, and the outdoor ambient temperature, the control method of the present application can jointly determine the operating opening degree of the electronic expansion valve based on multiple variables, improve the calculation accuracy of the operating opening degree, enable the electronic expansion valve to always work at an appropriate opening degree, and reduce the heating energy consumption of the air conditioner.

[0096] Of course, the determination of the operating opening degree of the electronic expansion valve can also be carried out based on other relationships between it and the above parameters, such as the fixed correspondence relationship between the above three parameters and the operating opening degree, etc.

[0097] In a more preferred embodiment, after "adjusting the opening degree of the electronic expansion valve to the operating opening degree", the heating control method further includes: obtaining the actual temperature of the subcooled pipe section 52; performing PID adjustment on the opening degree of the electronic expansion valve based on the difference between the theoretical temperature and the actual temperature.

[0098] By performing PID control on the opening degree of the electronic expansion valve based on the difference between the theoretical temperature and the actual temperature of the subcooled pipe section 52 after adjusting the opening degree of the electronic expansion valve to the operating opening degree, the control method of the present application can also dynamically, quickly, and accurately adjust the opening degree of the electronic expansion valve, preventing the problems of over-adjustment or overshoot of the electronic expansion valve.

[0099] The following combines Figure 2 and Figure 6 , and briefly introduces the control process of the control method of the air conditioner of the present application. Among them, Figure 6 is the logic diagram of the control method of the air conditioner of the present invention.

[0100] As Figure 2 and Figure 6 shown, in a possible implementation process, the air conditioner operates in heating mode → first obtains the outdoor ambient temperature T ao , and determines whether T ao < 5°C holds:

[0101] If T ao <5°C does not hold, adjust the effective length of the subcooling pipe section 52 to the shortest (if it is already in the shortest state, no adjustment is required), and maintain this state for continuous operation → Obtain the outdoor ambient temperature T during the operation ao and the operating frequency f of the compressor → Calculate the theoretical temperature T of the subcooling pipe section 52 based on formula (2) c → Calculate the operating opening B of the electronic expansion valve based on formula (3) → Control the electronic expansion valve to open to the opening B, so that the air conditioner operates with better heating energy efficiency and defrosting efficiency → After the air conditioner operates for 2 minutes, detect the actual temperature T of the subcooling pipe c1 → Calculate the theoretical temperature T c and the actual temperature T c1 Calculate the difference △T between them, and perform PID precise adjustment on the opening of the electronic expansion valve based on this difference △T to ensure the heating energy efficiency of the air conditioner and prevent over-adjustment or overshoot of the electronic expansion valve.

[0102] If T ao <5°C holds, first adjust the effective length of the subcooling pipe section 52 to the shortest, and continuously detect the temperature of the heat exchange pipe section 51 within a set time period of 2 minutes and calculate the temperature change rate K during these 2 minutes → If K ≤ -1 and lasts for 1 minute, control the opening and closing of the subcooling valves (55a, 55b, 55c), the confluence valves (57a, 57b, 57c) and the on-off valves (58a, 58b, 58c) to increase the effective length of the subcooling pipe section 52 → After increasing the effective length of the subcooling pipe section 52, obtain the outdoor ambient temperature T ao and the operating frequency f of the compressor → Calculate the theoretical temperature T of the subcooling pipe section 52 based on formula (2) c → Calculate the operating opening B of the electronic expansion valve based on formula (3) → Control the electronic expansion valve to open to the opening B, so that the air conditioner operates with better heating energy efficiency and defrosting efficiency → After the air conditioner operates for 2 minutes, detect the actual temperature T of the subcooling pipe c1 → Calculate the theoretical temperature T c and the actual temperature T c1 Calculate the difference △T between them, and perform PID precise adjustment on the opening of the electronic expansion valve based on this difference △T to ensure the heating energy efficiency of the air conditioner and prevent over-adjustment or overshoot of the electronic expansion valve → After the adjustment is completed, return to repeat the steps of collecting the temperature of the heat exchange pipe section 51, adjusting the effective length of the subcooling pipe based on the temperature change rate K, and adjusting the opening B of the electronic expansion valve until the effective length of the subcooling pipe section 52 increases to the maximum.

[0103] Those skilled in the art can understand that the above variable-frequency air conditioner also includes some other well-known structures, such as a processor, a controller, a memory, etc. Among them, the memory includes but is not limited to random access memory, flash memory, read-only memory, programmable read-only memory, volatile memory, non-volatile memory, serial memory, parallel memory, or registers, etc. The processor includes but is not limited to CPLD / FPGA, DSP, ARM processor, MIPS processor, etc. In order not to unnecessarily obscure the embodiments of the present disclosure, these well-known structures are not shown in the drawings.

[0104] Each component embodiment of the present invention can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the functions of some or all of the components in the server and client according to the embodiments of the present invention. The present invention can also be implemented as a device or apparatus program (for example, a PC program and a PC program product) for executing part or all of the methods described herein. Such a program for implementing the present invention can be stored on a PC-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0105] It should be noted that although the detailed steps of the method of the present invention are described in detail above, on the premise of not deviating from the basic principle of the present invention, those skilled in the art can combine, split, and change the order of the above steps. The technical solutions modified in this way do not change the basic concept of the present invention, and therefore also fall within the protection scope of the present invention.

[0106] Finally, it should be noted that although this embodiment is described in combination with a variable-frequency air conditioner, this is not intended to limit the protection scope of the present application. Those skilled in the art can also apply the present application to other types of air conditioners as long as the air conditioner has an outdoor unit condenser. For example, the present application can also be applied to a fixed-frequency air conditioner, etc.

[0107] So far, the technical solutions of the present invention have been described in combination with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. On the premise of not deviating from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. An outdoor unit condenser, characterized in that, The outdoor unit condenser includes a heat exchange pipe section, a subcooling pipe section, a throttling element, a subcooling connecting pipe, and a plurality of subcooling valves. The first end of the subcooling pipe section can be connected to the indoor unit evaporator through a main capillary tube. The first end and the second end of the subcooling pipe section are separated into n subcooling intervals by the plurality of subcooling valves. A plurality of the subcooling intervals are respectively connected to the first end of the throttling element through a subcooling connecting pipe. The second end of the throttling element is connected to the heat exchange pipe section. The plurality of subcooling valves are arranged to be able to adjust the effective length of the subcooling pipe section by controlling the opening and closing of each subcooling valve; Among them, the subcooling connecting pipes are arranged on the 1st to the n - 1th subcooling intervals starting from the first end of the subcooling pipe section; Among them, the effective length refers to the length of the part of the subcooling pipe section that has a subcooling effect. This length can be controlled by controlling the opening and closing of the subcooling valves. The longest effective length is the full length of the subcooling pipe section.

2. The outdoor unit condenser according to claim 1, characterized in that, The second end of the subcooling pipe section is connected to the heat exchange pipe section. The outdoor unit condenser further includes a confluence connecting pipe and a plurality of confluence valves. A plurality of the subcooling intervals are respectively connected to the second end of the throttling element through a confluence connecting pipe. Each confluence connecting pipe is provided with a confluence valve.

3. The outdoor unit condenser according to claim 2, characterized in that, The confluence connecting pipes are arranged on the 2nd to the nth subcooling intervals starting from the first end of the subcooling pipe section.

4. The outdoor unit condenser according to claim 1, characterized in that, The outdoor unit condenser further includes a plurality of on - off valves, and each of the plurality of subcooling connecting pipes is provided with an on - off valve.

5. The outdoor unit condenser according to claim 4, characterized in that, The on - off valve is a one - way valve, and the one - way valves are arranged on the 2nd to the n - 1th subcooling connecting pipes starting from the first end of the subcooling pipe section; or The on - off valve is a solenoid valve, and the solenoid valves are arranged on all the subcooling connecting pipes.

6. The outdoor unit condenser according to claim 1, characterized in that, The outdoor unit condenser further includes a defrosting temperature detection element arranged on the heat exchange pipe section. The defrosting temperature detection element can be connected to a controller so that the controller adjusts the opening and closing of the plurality of subcooling valves based on the temperature collected by the defrosting temperature detection element.

7. The outdoor unit condenser according to claim 1, wherein The throttling element is a regulating valve, and the regulating valve is arranged to open a set opening when the heat exchange medium flows from the indoor unit evaporator to the outdoor unit condenser, The outdoor unit condenser further includes a subcooling temperature detection element arranged on the subcooling pipe section. The subcooling temperature detection element can be connected to a controller so that the controller adjusts the opening of the regulating valve based on the temperature collected by the subcooling temperature detection element.

8. The outdoor unit condenser according to claim 1, wherein The subcooling pipe section is arranged on the windward side of the outdoor unit condenser; and / or The subcooling pipe section is arranged below the heat exchange pipe section.

9. An outdoor unit, characterized in that, The outdoor unit includes the outdoor unit condenser according to any one of claims 1 to 8.

10. A variable frequency air conditioner, characterized in that, The variable - frequency air conditioner includes the outdoor unit according to claim 9.

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