A heat pump air conditioning system and a defrosting control method thereof

Abstract

The present application relates to a kind of heat pump air conditioning system and its defrosting control method, heat pump air conditioning system includes the compressor, first four-way valve, indoor heat exchanger, throttling device and outdoor heat exchanger formed in turn in refrigerant circuit;Heat pump air conditioning system also includes controller, second four-way valve between outdoor heat exchanger and first four-way valve are arranged, and temperature sensor for detecting outdoor heat exchanger coil temperature;The controller includes outdoor unit motor current detection module and data processing module;Defrosting control method applied to above-mentioned heat pump air conditioning system is judged by the current size of the outdoor unit fan motor, wherein, current value A is critical point, current value is less than or equal to A enters the conventional defrosting mode second defrosting mode, current value is greater than A enters first defrosting mode, in this mode, by the cooperation of second four-way valve, refrigerant first from the bottom of outdoor unit enters upper portion and is prior to the frost layer of bottom.

Description

Technical Field

[0001] This invention relates to the field of heat pump air conditioning technology, and in particular to a heat pump air conditioning system and its defrosting control method. Background Technology

[0002] When a heat pump air conditioning system operates in low-temperature conditions, the fins of the outdoor unit will frost over due to the low surface temperature. Over time, this frost layer will form, leading to a decrease in the unit's heating capacity. Therefore, it is necessary to defrost the heat exchanger of the outdoor unit in a timely manner. The most common method for automatic defrosting of heat pump units is to switch from heating mode to cooling mode, using the high-temperature exhaust gas from the compressor to defrost. However, because the overall heat exchange area of ​​the outdoor unit's heat exchanger is large, it often takes 5-8 minutes or even longer to completely defrost it.

[0003] Because the refrigerant flow path in the heat exchanger is distributed from top to bottom, the refrigerant temperature is highest at the inlet and gradually decreases as it exchanges heat. Therefore, the frost layer in the upper and middle sections melts first, and the defrosted water slides down the fins. At this point, the unmelted frost layer at the bottom hinders drainage. When the frost layer is too thick, it can lead to incomplete defrosting, causing ice to form at the bottom of the heat exchanger in the outdoor unit of the air conditioner. Summary of the Invention

[0004] To address the aforementioned problems, the first objective of this invention is to provide a defrosting control method that can acquire the coil temperature of the outdoor heat exchanger and determine whether the outdoor unit needs defrosting. If defrosting is required, the method can acquire the current value of the outdoor heat exchanger fan motor and determine whether normal defrosting or defrosting from the bottom of the outdoor unit is required to remove the frost based on the magnitude of the current value. This solution has a simple structure and reliable judgment of defrosting conditions and defrosting efficiency. The second objective of this invention is to provide a heat pump air conditioning system with the aforementioned defrosting control method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A defrosting control method for a heat pump air conditioning system, applied to a heat pump air conditioning system comprising a compressor, a first four-way valve, an indoor heat exchanger, a throttling device, and an outdoor heat exchanger arranged sequentially in a refrigerant circuit; characterized in that:

[0007] The heat pump air conditioning system also includes a controller, a second four-way valve disposed between the outdoor heat exchanger and the first four-way valve, and a temperature sensor for detecting the temperature of the outdoor heat exchanger coil; the controller includes an outdoor unit motor current detection module and a data processing module; the defrosting control method includes the following steps:

[0008] Step 1:

[0009] When the air conditioner is running in heating mode, the controller obtains the outdoor heat exchanger coil temperature THd through the temperature sensor and determines whether the air conditioner needs to enter defrost mode. If not, the air conditioner continues to run in heating mode. If it does, the air conditioner enters defrost mode, and the controller obtains the outdoor heat exchanger fan motor current value I through the outdoor unit motor current detection module.

[0010] Step 2:

[0011] The controller uses the data processing module to determine whether the current value I is greater than the threshold A;

[0012] If I > A, close the first four-way valve and open the second four-way valve. The air conditioner enters the first defrost mode, and the outdoor heat exchanger begins to defrost from the bottom.

[0013] If I≤A, close the first four-way valve and the second four-way valve, and the air conditioner enters the second defrost mode. The air conditioner enters the first defrost mode and starts defrosting from the upper middle part.

[0014] Step 3:

[0015] When I > A, the air conditioner is in the first defrost mode. When THd > B or the air conditioner has been running in this mode for a period of time T = t1, the second four-way valve is closed, and the air conditioner enters the second defrost mode. After running in the second defrost mode for a period of time T = t2, the air conditioner exits the second defrost mode.

[0016] When I≤A, the air conditioner is in the second defrost mode. When THd>C or the air conditioner continues to operate in this mode for a duration T=t3, it exits the second defrost mode.

[0017] Preferably, the first four-way valve includes valve port C1, valve port D1, valve port E1 and valve port S1; the second four-way valve includes valve port C2, valve port D2, valve port E2 and valve port S2.

[0018] When the first four-way valve is in the closed state, valve port E1 and valve port S1 are connected, and valve port C1 and valve port D1 are connected; when the first four-way valve is in the open state, valve port D1 and valve port E1 are connected, and valve port C1 and valve port S1 are connected.

[0019] When the second four-way valve is in the closed state, valve port E2 and valve port S2 are connected, and valve port C2 and valve port D2 are connected; when the second four-way valve is in the open state, valve port D2 and valve port E2 are connected, and valve port C2 and valve port S2 are connected.

[0020] Preferably, when the air conditioner is in heating mode, the refrigerant passes sequentially through the compressor discharge port, valve port D1, valve port E1, indoor heat exchanger inlet, indoor heat exchanger outlet, throttling device, valve port S2, valve port E2, outdoor heat exchanger inlet, outdoor heat exchanger outlet, valve port C2, valve port D2, valve port C1, and valve port S1 to the compressor suction port.

[0021] When the air conditioner is in the first defrost mode, the refrigerant passes sequentially through the compressor discharge port, valve port D1, valve port C1, valve port D2, valve port E2, outdoor heat exchanger inlet, outdoor heat exchanger outlet, valve port C2, valve port S2, throttling device, indoor heat exchanger outlet, indoor heat exchanger inlet, valve port E1, and valve port S1 to the compressor suction port.

[0022] When the air conditioner is in the second defrost mode, the refrigerant passes sequentially through the compressor discharge port, valve port D1, valve port C1, outdoor heat exchanger outlet, outdoor heat exchanger inlet, valve port E2, valve port S2, throttling device, indoor heat exchanger outlet, indoor heat exchanger inlet, valve port E1, and valve port S1 to the compressor suction port.

[0023] Preferably, the current threshold A is the current value at the critical point of frost thickness of the outdoor heat exchanger.

[0024] A heat pump air conditioning system, applied to the defrosting control method for the heat pump air conditioning system described in any one of the above.

[0025] This invention employs the aforementioned technical solution to address the issue of thick frost buildup at the bottom of existing outdoor units, which cannot be completely removed by normal defrosting methods. The solution adds a four-way valve (a second four-way valve) to the refrigerant circuit. This valve directly measures the temperature of the outdoor unit's coils to determine if defrosting is required. If the coil surface temperature is low, defrosting is necessary. The controller measures the current flowing through the outdoor unit's fan motor via the outdoor unit motor current detection module and determines the thickness of the frost layer on the outdoor heat exchanger. Furthermore, using current value A as a critical point, a current value less than or equal to A enters the conventional defrosting mode (second defrosting mode), while a current value greater than A enters the first defrosting mode. In this mode, in conjunction with the second four-way valve, the refrigerant first enters from the bottom of the outdoor unit and exits at the top, prioritizing the removal of the frost layer at the bottom.

[0026] It should be noted that the temperature sensor on the outdoor unit coil is used to detect and determine the temperature of the outdoor unit coil. It mainly determines the defrosting conditions by the difference between the temperature and the outdoor ambient temperature.

[0027] It should also be noted that frost formation on the outdoor unit increases the resistance to the rotation of the outdoor fan blades, which in turn increases the load and power of the outdoor fan. When the voltage is constant, the power of the outdoor fan increases and the current also increases. Therefore, the thickness of the frost layer on the heat exchanger can be reflected by the motor current.

[0028] In addition, the THd values ​​B and C are reference values ​​for judging the frosting on the surface of the outdoor heat exchanger fins. It should be noted that due to different temperature sensor placement positions, temperature measurements may have deviations; different air conditioning equipment uses different heat exchanger fin materials, so the THd values ​​are not completely consistent and need to be set according to the actual test results. Attached Figure Description

[0029] Figure 1 This is a system diagram of a heat pump air conditioning system used in the defrosting control method of this case.

[0030] Figure 2 This is a refrigerant flow diagram for the air conditioner in heating mode in this case.

[0031] Figure 3 This is a refrigerant flow diagram for the air conditioner in the first defrost mode in this case.

[0032] Figure 4 This is a refrigerant flow diagram for the air conditioner in the second defrost mode in this case.

[0033] Figure 5 This is a simplified structural diagram of an outdoor heat exchanger (outdoor unit).

[0034] Figure 6 This is the control logic block diagram for this case. Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] like Figures 1-5 The heat pump air conditioning system shown includes a compressor 1, a first four-way valve 2, an indoor heat exchanger 3, a throttling device 4, and an outdoor heat exchanger 5, which are arranged in sequence to form a refrigerant circuit.

[0041] The heat pump air conditioning system also includes a controller, a second four-way valve 6 disposed between the outdoor heat exchanger 5 and the first four-way valve 2, and a temperature sensor 100 for detecting the coil temperature of the outdoor heat exchanger 5; the controller includes an outdoor unit motor current detection module and a data processing module.

[0042] like Figure 6 The method for defrosting control of a heat pump air conditioning system shown is applied to the above-mentioned... Figures 1-5 In a heat pump air conditioning system, the defrosting control method includes the following steps:

[0043] Step 1:

[0044] When the air conditioner is running in heating mode, the controller obtains the coil temperature THd of the outdoor heat exchanger 5 through the temperature sensor 100 and determines whether the air conditioner needs to enter defrost mode. If not, the air conditioner continues to run in heating mode. If it needs to enter defrost mode, the controller obtains the fan motor current value I of the outdoor heat exchanger 5 through the outdoor unit motor current detection module.

[0045] Step 2:

[0046] The controller uses the data processing module to determine whether the current value I is greater than the threshold A;

[0047] If I > A, close the first four-way valve 2 and open the second four-way valve 6. The air conditioner enters the first defrost mode, and the outdoor heat exchanger 5 starts defrosting from the bottom.

[0048] If I≤A, close the first four-way valve 2 and the second four-way valve 6, and the air conditioner enters the second defrost mode. The air conditioner enters the first defrost mode and starts defrosting from the upper middle part.

[0049] Step 3:

[0050] When I > A, the air conditioner is in the first defrost mode. When THd > B or the air conditioner has been running in this mode for a period of time T = t1, the second four-way valve 6 is closed, and the air conditioner enters the second defrost mode. After running in the second defrost mode for a period of time T = t2, the air conditioner exits the second defrost mode.

[0051] When I≤A, the air conditioner is in the second defrost mode. When THd>C or the air conditioner continues to operate in this mode for a duration T=t3, it exits the second defrost mode.

[0052] Furthermore, the first four-way valve 2 includes valve port C1, valve port D1, valve port E1 and valve port S1; the second four-way valve 6 includes valve port C2, valve port D2, valve port E2 and valve port S2;

[0053] When the first four-way valve 2 is in the closed state, valve port E1 and valve port S1 are connected, and valve port C1 and valve port D1 are connected; when the first four-way valve 2 is in the open state, valve port D1 and valve port E1 are connected, and valve port C1 and valve port S1 are connected.

[0054] When the second four-way valve 6 is in the closed state, valve port E2 and valve port S2 are connected, and valve port C2 and valve port D2 are connected; when the second four-way valve 6 is in the open state, valve port D2 and valve port E2 are connected, and valve port C2 and valve port S2 are connected.

[0055] Furthermore, when the air conditioner is in heating mode, the refrigerant passes sequentially through the compressor discharge port 7, valve port D1, valve port E1, indoor heat exchanger inlet 8, indoor heat exchanger outlet 9, throttling device 4, valve port S2, valve port E2, outdoor heat exchanger inlet 10, outdoor heat exchanger outlet 11, valve port C2, valve port D2, valve port C1, and valve port S1 to the compressor suction port 12.

[0056] When the air conditioner is in the first defrost mode, the refrigerant passes sequentially through the compressor discharge port 7, valve port D1, valve port C1, valve port D2, valve port E2, outdoor heat exchanger inlet 10, outdoor heat exchanger outlet 11, valve port C2, valve port S2, throttling device 4, indoor heat exchanger outlet 9, indoor heat exchanger inlet 8, valve port E1, and valve port S1 to the compressor suction port 12.

[0057] When the air conditioner is in the second defrost mode, the refrigerant passes sequentially through the compressor exhaust port 7, valve port D1, valve port C1, outdoor heat exchanger outlet 11, outdoor heat exchanger inlet 10, valve port E2, valve port S2, throttling device 4, indoor heat exchanger outlet 9, indoor heat exchanger inlet 8, valve port E1, and valve port S1 to the compressor suction port 12.

[0058] Furthermore, the current threshold A is the current value at the critical point of frost thickness in the outdoor heat exchanger 5.

[0059] In this specific embodiment, addressing the issue of thick frost buildup at the bottom of existing outdoor units, which cannot be completely removed by normal defrosting methods, the above solution adds a four-way valve, namely the second four-way valve, to the refrigerant circuit. This valve directly measures the temperature of the outdoor unit's coils to determine if defrosting is required. If the coil surface temperature is low, defrosting is necessary. The controller measures the current flowing through the outdoor unit's fan motor via the outdoor unit motor current detection module and determines the thickness of the frost layer on the outdoor heat exchanger. Furthermore, using current value A as a critical point, a current value less than or equal to A enters the conventional defrosting mode, namely the second defrosting mode; a current value greater than A enters the first defrosting mode. In this mode, in conjunction with the second four-way valve, the refrigerant first enters from the bottom of the outdoor unit and exits at the top, prioritizing the removal of the frost layer at the bottom.

[0060] It should be noted that the temperature sensor on the outdoor unit coil is used to detect and determine the temperature of the outdoor unit coil. It mainly determines the defrosting conditions by the difference between the temperature and the outdoor ambient temperature.

[0061] It should also be noted that frost formation on the outdoor unit increases the resistance to the rotation of the outdoor fan blades, which in turn increases the load and power of the outdoor fan. When the voltage is constant, the power of the outdoor fan increases and the current also increases. Therefore, the thickness of the frost layer on the heat exchanger can be reflected by the motor current.

[0062] In addition, the THd values ​​B and C are reference values ​​for judging the frosting on the surface of the outdoor heat exchanger fins. It should be noted that due to different temperature sensor placement positions, temperature measurements may have deviations; different air conditioning equipment uses different heat exchanger fin materials, so the THd values ​​are not completely consistent and need to be set according to the actual test results.

[0063] It should also be noted that the industry standard for defrosting entry is to determine the difference between the outer plate temperature and the ambient temperature. This case does not require defrosting entry conditions.

[0064] In this case, the outdoor unit fan motor current value I varies with the fan load. When the heat exchanger frosts, the fan current gradually increases as the frost layer thickens. Therefore, the frost thickness can be determined by the motor current, and its value depends on the actual test data of the air conditioner. It should be noted that the specific defrosting effect will vary due to differences in heat exchanger fin material, spacing, number of rows, etc. Therefore, the definition of frost thickness and the A value need to be set according to the specific unit equipment and actual test conditions.

[0065] The heat pump air conditioning system operates normally in heating mode and determines the defrosting conditions. Once the defrosting conditions are met, it judges the situation based on the fan current value. If the outdoor unit fan current value is greater than value A, it enters the first defrosting mode.

[0066] With the first four-way valve closed and the second four-way valve open, the refrigerant enters the second four-way valve from the compressor through the D1-C1 port of the first four-way valve, then flows through the D2-E2 port to the outdoor heat exchanger, moving from the bottom to the top. After exchanging heat with the air in the outdoor heat exchanger, it flows through the C2-S2 port of the second four-way valve to the throttling device, then through the indoor heat exchanger, and finally returns to the compressor through the E1-S1 port of the first four-way valve. In this mode, the high-temperature refrigerant enters from the bottom of the outdoor unit's heat exchanger first, preferentially melting the bottom frost layer, thus preventing frost from obstructing the water flow in the lower half. However, due to resistance loss, it maintains an upward flow, which is not conducive to rapid defrosting. Therefore, once the frost layer on the lower 1 / 3 of the heat exchanger is completely removed, switch to the normal defrosting mode, i.e., the second defrosting mode. That is, when the defrosting logic is followed until the external plate temperature THd > B or the duration T = t1, close the second four-way valve and enter the second stage of operation. After the duration T = t2, exit the second defrosting mode.

[0067] If the fan current value is less than or equal to the value A, enter the second defrosting mode:

[0068] The first four-way valve is closed, and the second four-way valve is also closed. Refrigerant enters the second four-way valve from the compressor through the first four-way valve's D1-C1 port, then flows through the D2-C2 port to the outdoor heat exchanger, flowing from the top to the bottom. After exchanging heat with the air in the outdoor heat exchanger, it flows through the second four-way valve's E2-S2 port to the throttling device, then through the indoor heat exchanger, and after heat exchange within the indoor unit, returns to the compressor through the first four-way valve's E1-S1 port. When the outdoor unit temperature THd > C or the duration T = t3, the second defrost mode is exited.

[0069] In both of the above situations, after exiting the second defrost mode, close the first four-way valve and the second four-way valve, and the air conditioner will enter the normal heating mode.

[0070] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0071] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A defrosting control method for a heat pump air conditioning system, applied to a heat pump air conditioning system comprising a compressor (1), a first four-way valve (2), an indoor heat exchanger (3), a throttling device (4), and an outdoor heat exchanger (5) arranged sequentially to form a refrigerant circuit; characterized in that: The heat pump air conditioning system also includes a controller, a second four-way valve (6) located between the outdoor heat exchanger (5) and the first four-way valve (2), and a temperature sensor (100) for detecting the coil temperature of the outdoor heat exchanger (5); the controller includes an outdoor unit motor current detection module and a data processing module; The first four-way valve (2) includes valve port (C1), valve port (D1), valve port (E1) and valve port (S1); the second four-way valve (6) includes valve port (C2), valve port (D2), valve port (E2) and valve port (S2); The first four-way valve (2) is in the closed state, with valve port (E1) and valve port (S1) connected, and valve port (C1) and valve port (D1) connected; the first four-way valve (2) is in the open state, with valve port (D1) and valve port (E1) connected, and valve port (C1) and valve port (S1) connected. The second four-way valve (6) is in the closed state, with valve port (E2) and valve port (S2) connected, and valve port (C2) and valve port (D2) connected; the second four-way valve (6) is in the open state, with valve port (D2) and valve port (E2) connected, and valve port (C2) and valve port (S2) connected. The defrosting control method includes the following steps: Step 1: When the air conditioner is running in heating mode, the controller obtains the coil temperature THd of the outdoor heat exchanger (5) through the temperature sensor (100) and determines whether the air conditioner needs to enter defrost mode. If not, the air conditioner continues to run in heating mode. If it is needed, the air conditioner enters defrost mode and the controller obtains the fan motor current value I of the outdoor heat exchanger (5) through the outdoor unit motor current detection module. Step 2: The controller uses the data processing module to determine whether the current value I is greater than the threshold A; If I > A, close the first four-way valve (2) and open the second four-way valve (6). The air conditioner enters the first defrosting mode, and the outdoor heat exchanger (5) starts defrosting from the bottom. If I≤A, close the first four-way valve (2) and the second four-way valve (6), and the air conditioner enters the second defrosting mode. The outdoor heat exchanger (5) starts defrosting from the middle and upper part. Step 3: When I > A, the air conditioner is in the first defrost mode. When THd > B or the air conditioner continues to operate in this mode for a time T = t1, the second four-way valve (6) is closed, and the air conditioner enters the second defrost mode. After the air conditioner continues to operate in the second defrost mode for a time T = t2, it exits the second defrost mode. When I≤A, the air conditioner is in the second defrost mode. When THd>C or the air conditioner continues to operate in this mode for a duration T=t3, it exits the second defrost mode.

2. The defrosting control method for a heat pump air conditioning system according to claim 1, characterized in that: When the air conditioner is in heating mode, the refrigerant passes through the compressor exhaust port (7), valve port (D1), valve port (E1), indoor heat exchanger inlet (8), indoor heat exchanger outlet (9), throttling device (4), valve port (S2), valve port (E2), outdoor heat exchanger inlet (10), outdoor heat exchanger outlet (11), valve port (C2), valve port (D2), valve port (C1), and valve port (S1) to the compressor suction port (12). When the air conditioner is in the first defrost mode, the refrigerant passes through the compressor exhaust port (7), valve port (D1), valve port (C1), valve port (D2), valve port (E2), outdoor heat exchanger inlet (10), outdoor heat exchanger outlet (11), valve port (C2), valve port (S2), throttling device (4), indoor heat exchanger outlet (9), indoor heat exchanger inlet (8), valve port (E1), valve port (S1) to the compressor suction port (12). When the air conditioner is in the second defrost mode, the refrigerant passes through the compressor exhaust port (7), valve port (D1), valve port (C1), outdoor heat exchanger outlet (11), outdoor heat exchanger inlet (10), valve port (E2), valve port (S2), throttling device (4), indoor heat exchanger outlet (9), indoor heat exchanger inlet (8), valve port (E1), valve port (S1) to the compressor suction port (12).

3. The defrosting control method for a heat pump air conditioning system according to claim 1, characterized in that: The current threshold A is the current value at the critical point of frost thickness of the outdoor heat exchanger (5).

4. A heat pump air conditioning system, characterized in that: The defrosting control method for a heat pump air conditioning system as described in any one of claims 1 to 3 above.

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