Defrosting control method and system of heat pump unit and heat pump unit

Abstract

The invention relates to the technical field of electric appliances, in particular to a defrosting control method and system of a heat pump unit and the heat pump unit, and aims to solve the problem that a plate heat exchanger is frost-cracked during defrosting of an existing heat pump unit. In order to achieve the purpose, the defrosting control method of the heat pump unit comprises the steps that according to the condenser temperature obtained by a defrosting sensor, whether the heat pump unit meets the first defrosting condition or not is judged; according to the waterway state information of the plate heat exchanger, whether the heat pump unit meets a second defrosting condition or not is judged; when the heat pump unit meets the first defrosting condition and the second defrosting condition at the same time, the heat pump unit is controlled to enter a first defrosting mode; and when the heat pump unit meets the first defrosting condition and does not meet the second defrosting condition, the heat pump unit is controlled to enter a second defrosting mode. The defrosting mode can be flexibly adjusted, so that the plate heat exchanger is prevented from being in a low-temperature environment, the plate heat exchanger is prevented from frost cracking, and the service life of the plate heat exchanger is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical appliances, and in particular to a defrosting control method and system for a heat pump unit and a heat pump unit. Background Art

[0002] The heating principle of the existing heat pump unit is to use the high-temperature refrigerant gas discharged from the compressor and the low-temperature cold water to perform two-phase heat exchange in the brazed plate heat exchanger, discharge hot water, and meet the user's heating needs.

[0003] However, for heat pump units, frost on the heat exchanger is inevitable during heating. When the frost reaches a certain level, defrosting must be performed. The common defrosting method is to switch to the refrigeration mode and use high-temperature gas to melt the frost layer. At this time, the brazed heat exchanger performs refrigeration operation, which will reduce the inlet and outlet water temperatures. In particular, users are at risk of freezing and cracking the plate heat exchanger when the water flow rate is low and the outlet water temperature is low. Summary of the invention

[0004] The present invention aims to solve the above technical problem, that is, to solve the problem that the plate heat exchanger of the existing heat pump unit will freeze and crack during defrosting.

[0005] In a first aspect, the present invention provides a defrost control method for a heat pump unit, the heat pump unit comprising a compressor, a condenser, an indoor unit, a gas-liquid separator, and a plate heat exchanger connected to form a refrigerant circulation loop, the condenser being provided with a defrost sensor, the plate heat exchanger being provided with a water pipeline; a first end of the compressor being connected to a first end of the condenser, a second end of the condenser being connected to a first end of the indoor unit, a second end of the indoor unit being connected to a first end of the gas-liquid separator, and a second end of the gas-liquid separator being connected to a second end of the compressor; The defrost control method includes: judging whether the heat pump unit meets the first defrost condition according to the condenser temperature obtained by the defrost sensor; judging whether the heat pump unit meets the second defrost condition according to the water path status information of the plate heat exchanger; when the heat pump unit meets both the first defrost condition and the second defrost condition, controlling the heat pump unit to enter the first defrost mode; when the heat pump unit meets the first defrost condition and does not meet the second defrost condition, controlling the heat pump unit to enter the second defrost mode.

[0006] Furthermore, based on the condenser temperature obtained by the defrost sensor, it is determined whether the heat pump unit meets the conditions for entering the first defrost, including: based on the condenser temperature obtained by the defrost sensor; comparing the condenser temperature with the set temperature; when the condenser temperature is less than or equal to the set temperature of the condenser, determining that the heat pump unit meets the conditions for entering the first defrost.

[0007] Furthermore, the plate heat exchanger is provided with a water inlet and a water outlet, the water inlet is provided with a first temperature sensor and a flow meter, the water path status information includes the water inlet temperature and the water inlet flow rate, and according to the water path status information of the plate heat exchanger, it is judged whether the heat pump unit meets the conditions for entering the second defrost, including: judging whether the water inlet temperature obtained by the first temperature sensor is less than or equal to the set water inlet temperature; if so, continuing to judge whether the water inlet flow rate at the water inlet obtained by the flow meter is less than or equal to the set water inlet flow rate, and if so, it is determined that the heat pump unit meets the conditions for entering the second defrost.

[0008] Furthermore, the set water inlet temperature is 5°C to 30°C.

[0009] Furthermore, the set flow rate is 10% to 30% of the maximum flow rates of the water inlet and the water outlet.

[0010] Furthermore, it also includes: when the heat pump unit is in the first defrost mode or the second defrost mode, determining whether the condenser temperature obtained by the defrost sensor is greater than or equal to the set defrost temperature; if so, continuing to determine the duration of the condenser temperature greater than the set defrost temperature; when the duration is greater than the set duration, turning off the first defrost mode or the second defrost mode of the heat pump unit and entering the heating mode.

[0011] Furthermore, the heat pump unit also includes a first four-way valve and a second four-way valve, the first four-way valve is arranged between the indoor unit, the gas-liquid separator and the compressor, and the second four-way valve is arranged between the compressor, the condenser and the plate heat exchanger; based on the fact that the heat pump unit is in the first defrost mode, the first four-way valve is powered off and the second four-way valve is powered off, the refrigerant enters the condenser after passing through the second four-way valve from the compressor, and then enters the indoor unit, and then the refrigerant passes through the first four-way valve and then flows into the gas-liquid separator, and then flows back to the compressor; based on the fact that the heat pump unit is in the second defrost mode, the first four-way valve is powered off and the second four-way valve is opened, the refrigerant enters the plate heat exchanger after passing through the second four-way valve from the compressor, and then enters the condenser, and then the refrigerant passes through the second four-way valve and then flows into the gas-liquid separator, and then flows back to the compressor.

[0012] Furthermore, a first switch is provided between the plate heat exchanger and the condenser; when the heat pump unit is in the second defrost mode, the first switch is turned on, and the refrigerant passes through the plate heat exchanger and then flows into the condenser through the first switch.

[0013] When adopting the above technical scheme, the present invention can adjust the defrost mode according to the condenser temperature sensed by the defrost sensor of the heat pump unit and the water path status information of the plate heat exchanger, so that when the condenser temperature is low and the water temperature of the plate heat exchanger is too low and the water flow rate is small, the first defrost mode is operated to avoid the refrigerant passing through the plate heat exchanger, thereby avoiding the plate heat exchanger from being frozen and cracked by the low-temperature refrigerant. When the condenser temperature sensed by the defrost sensor is within a safe range, the second defrost mode is operated, and defrosting can be performed quickly while maintaining the safety of the plate heat exchanger, thereby improving the defrost efficiency of the condenser.

[0014] In a second aspect, the present invention provides a defrost control system for a heat pump unit, the heat pump unit comprising a compressor, a condenser, an indoor unit, a gas-liquid separator, and a plate heat exchanger connected to form a refrigerant circulation loop, the condenser being provided with a defrost sensor, and the plate heat exchanger being provided with a water pipeline; a first end of the compressor being connected to a first end of the condenser, a second end of the condenser being connected to a first end of the indoor unit, a second end of the indoor unit being connected to a first end of the gas-liquid separator, and a second end of the gas-liquid separator being connected to a second end of the compressor; the defrost control system comprising: entering a first defrost condition determination module, which is configured to determine whether the heat pump unit meets the first defrost condition based on the condenser temperature obtained by the defrost sensor; entering a second defrost condition determination module, which is configured to determine whether the heat pump unit meets the second defrost condition based on the water pipeline status information of the plate heat exchanger.

[0015] The present invention can determine the defrost mode to be performed according to the actual conditions of the condenser and the plate heat exchanger in the operation of the heat pump unit, thereby realizing automatic control of the defrost mode of the heat pump unit, improving the defrost efficiency of the heat pump unit, avoiding freezing and cracking of the plate heat exchanger, and improving the safety of the heat pump unit.

[0016] In a third aspect, the present invention provides a heat pump unit, comprising the defrost control system of the heat pump unit as described above.

[0017] The heat pump unit of the present invention has the defrost control system of the heat pump unit as described above, and thus has the beneficial effects of the defrost control system of the heat pump unit, improves the defrost efficiency of the heat pump unit, avoids the plate heat exchanger from being frozen and cracked at low temperatures, and improves the stability of the plate heat exchanger in the heat pump unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a flow chart of a defrosting control method for a heat pump unit in an embodiment of the present application;

[0020] Figure 2 This is a schematic diagram of the heat pump unit operating in the first defrost mode in the embodiment of the present application;

[0021] Figure 3 This is a schematic diagram of the heat pump unit operating in the second defrost mode in an embodiment of the present application;

[0022] Figure 4 This is a schematic diagram of the heating mode of the heat pump unit in the embodiment of the present application.

[0023] Reference numerals:

[0024] 1. Plate heat exchanger; 11. Water inlet; 12. Water outlet; 13. First temperature sensor; 14. Second temperature sensor;

[0025] 2. Compressor; 3. Gas-liquid separator;

[0026] 4. Condenser; 41. Defrost sensor;

[0027] 5. Indoor unit;

[0028] 61. First four-way valve; 62. Second four-way valve;

[0029] 71. Liquid pipe stop valve; 72. Gas pipe stop valve;

[0030] 81. First switch; 82. Second switch. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0032] First, it should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] like Figure 1 As shown, the present invention provides a defrosting control method for a heat pump unit, the heat pump unit includes a compressor 2, a condenser 4, an indoor unit 5, a gas-liquid separator 3, and a plate heat exchanger 1 connected to form a refrigerant circulation loop, the condenser 4 is provided with a defrost sensor 41, and the plate heat exchanger 1 is provided with a water pipeline;

[0035] The first end of the compressor 2 is connected to the first end of the condenser 4, the second end of the condenser 4 is connected to the first end of the indoor unit 5, the second end of the indoor unit 5 is connected to the first end of the gas-liquid separator 3, and the second end of the gas-liquid separator 3 is connected to the second end of the compressor 2;

[0036] Defrost control methods include:

[0037] According to the temperature of the condenser 4 obtained by the defrost sensor 41, it is judged whether the heat pump unit meets the first defrost condition;

[0038] According to the water channel status information of the plate heat exchanger 1, it is judged whether the heat pump unit meets the second defrosting condition;

[0039] When the heat pump unit meets both the first defrost condition and the second defrost condition, the heat pump unit is controlled to enter the first defrost mode;

[0040] When the heat pump unit meets the first defrost condition but does not meet the second defrost condition, the heat pump unit is controlled to enter the second defrost mode.

[0041] The present invention can adjust the defrost mode according to the condenser temperature sensed by the defrost sensor 41 of the heat pump unit and the water path status information of the plate heat exchanger 1, so that when the temperature of the condenser 4 is low and the water temperature of the plate heat exchanger 1 is too low and the water flow rate is small, the first defrost mode is operated to avoid the refrigerant from passing through the plate heat exchanger 1, thereby avoiding the plate heat exchanger 1 from being frozen and cracked by the low-temperature refrigerant. When the temperature of the condenser 4 sensed by the defrost sensor 41 is within a safe range, the second defrost mode is operated to quickly defrost while maintaining the safety of the plate heat exchanger 1, thereby improving the defrost efficiency of the condenser 4.

[0042] like Figure 2 and Figure 3 As shown, the plate heat exchanger 1 is provided with a water inlet 11 and a water outlet 12, the water inlet 11 is provided with a first temperature sensor 13 and a flow meter, the water path state information includes the water inlet temperature and the water inlet flow, and according to the water path state information of the plate heat exchanger 1, it is judged whether the heat pump unit meets the second defrosting condition, including;

[0043] Determine whether the water inlet temperature acquired by the first temperature sensor 13 is less than or equal to the set water inlet temperature;

[0044] If yes, then continue to determine whether the water inlet flow rate at the water inlet 11 obtained by the flow meter is less than or equal to the set water inlet flow rate.

[0045] If so, it is determined that the heat pump unit meets the conditions for entering the second defrost.

[0046] When the inlet water temperature is greater than the set inlet water temperature, the water flow will not drop to the freezing point after absorbing heat in the plate heat exchanger 1, that is, it will not freeze in the plate heat exchanger, thereby maintaining the stability of the plate heat exchanger 1. When the inlet water temperature is less than or equal to the set temperature, the inlet water temperature is low at this time, and the water flow may freeze in the plate heat exchanger 1. At this time, it is necessary to continue to judge the water flow rate. When the water flow rate is large under the condition of low inlet water temperature, the water flow will not freeze in the plate heat exchanger. When the water flow rate is small under the condition of low inlet water temperature, the water flow is judged to be likely to freeze in the plate heat exchanger. It is then judged that the heat pump unit meets the conditions for entering the second defrost, and the heat pump unit needs to operate the first defrost mode.

[0047] The plate heat exchanger may be frozen and cracked mainly because the water flow has dropped to the freezing point before it flows out of the plate heat exchanger 1, causing the plate heat exchanger 1 to be frozen and cracked. When the inlet water temperature is high, the water flow has enough heat and will not freeze in the plate heat exchanger 1. When the water flow temperature is high and the water flow rate is large, the water flow will not freeze in the plate heat exchanger 1 either. Therefore, the stability of the plate heat exchanger 1 can be ensured by controlling the inlet water temperature and the water flow rate.

[0048] A second temperature sensor is provided at the water outlet 12 of the plate heat exchanger 1 to detect the outlet water temperature, thereby assisting in determining the heat exchange condition between the water flow in the plate heat exchanger 1 and the refrigerant.

[0049] In practical applications, those skilled in the art can set the flow meter at any position of the water pipeline, for example, at the water inlet 11, inside the plate heat exchanger 1, at the water outlet 12, etc. Such adjustment and change of the setting position of the flow meter does not deviate from the scope and range of the present invention and should be included in the protection scope of the present invention.

[0050] In practical applications, the set water inlet temperature can be 5°C to 30°C, for example, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, etc. Such adjustments and changes to the set water inlet temperature do not deviate from the scope and range of the present invention and should be included in the protection scope of the present invention.

[0051] Optionally, the inlet water temperature is set to 10°C.

[0052] The water inlet pipe is provided with a water inlet valve, which has different valve openings, and different valve openings correspond to different water inlet flows.

[0053] In practical applications, other water control switches may be provided at the water inlet 11. Such adjustments and changes to the water control switches at the water inlet 11 do not deviate from the scope and range of the present invention and should be included in the protection scope of the present invention.

[0054] In practical applications, the flow rate is set to 10%, 20%, 30%, etc. of the maximum flow rate of the water inlet and outlet. Such adjustment and change of the set flow rate relative to the maximum flow rate of the water inlet and outlet does not deviate from the scope and range of the present invention and should be included in the protection scope of the present invention.

[0055] Optionally, the flow rate is set to 30% of the maximum flow rate of the water inlet and the water outlet.

[0056] like Figure 2 and Figure 3 As shown, the defrost control method of the heat pump unit further includes: when the heat pump unit is in the first defrost mode or the second defrost mode, determining whether the condenser temperature obtained by the defrost sensor 41 is greater than or equal to the set defrost temperature,

[0057] If so, continue to determine the duration of the condenser temperature being greater than the set defrost temperature. When the duration is greater than the set duration, turn off the first defrost mode or the second defrost mode of the heat pump unit and enter the heating mode.

[0058] When the heat pump unit has been in the first defrost mode or the second defrost mode for a period of time, the frost on the condenser may have been removed. At this time, the condenser temperature sensed by the defrost sensor will increase. Therefore, it is only necessary to determine that the temperature sensed by the defrost sensor is greater than the set defrost temperature and the duration exceeds the set time. The condenser defrost is then determined to be complete and the heat pump unit enters the heating mode. This can accurately control the defrost time of the heat pump unit and save energy consumption of the heat pump unit.

[0059] In practical applications, the set defrost temperature can be 5°C to 20°C, for example, 5°C, 10°C, 15°C, 20°C, etc. Such adjustment and change of the set defrost temperature does not deviate from the scope and range of the present invention and should be included in the protection scope of the present invention.

[0060] Optionally, set the defrost temperature to 15°C.

[0061] In practical applications, the set duration can be 1min to 5min, for example, 1min, 2min, 3min, 4min, 5min, etc. Such adjustment and change of the set duration does not deviate from the scope and range of the present invention and should be included in the protection scope of the present invention.

[0062] Optionally, set the duration to 1 minute.

[0063] like Figure 2 and Figure 3 As shown, judging whether the heat pump unit meets the first defrosting condition according to the condenser temperature obtained by the defrost sensor 41 includes:

[0064] Get the condenser temperature based on the defrost sensor;

[0065] Compare the condenser temperature to the set temperature;

[0066] When the condenser temperature is less than or equal to the set temperature of the condenser, it is determined that the heat pump unit meets the first defrosting condition.

[0067] The heat pump unit can sense the temperature of the condenser through the defrost sensor, so as to accurately control the heat pump unit to defrost accordingly, avoiding the condenser frosting affecting the operation of the heat pump unit and improving the working efficiency of the heat pump unit.

[0068] In practical applications, the set temperature can be 0°C to 3°C, for example, 0°C, 1°C, 2°C, 3°C, etc. Such adjustment and change of the set temperature does not deviate from the scope and range of the present invention and should be included in the protection scope of the present invention.

[0069] Optionally, set the defrost temperature to 0°C.

[0070] like Figure 2 and Figure 3 As shown, the heat pump unit further includes a first four-way valve 61 and a second four-way valve 62, wherein the first four-way valve 61 is disposed between the indoor unit 5, the gas-liquid separator 3 and the compressor 2, and the second four-way valve 62 is disposed between the compressor 2, the condenser 4 and the plate heat exchanger 1;

[0071] When the heat pump unit is in the first defrosting mode, the first four-way valve 61 is de-energized and the second four-way valve 62 is de-energized, and the refrigerant enters the condenser 4 from the compressor 2 through the second four-way valve 62, and then enters the indoor unit 5, and then the refrigerant passes through the first four-way valve 61 and flows into the gas-liquid separator 3, and then flows back to the compressor 2;

[0072] When the heat pump unit is in the second defrost mode, the first four-way valve 61 is powered off and the second four-way valve 62 is opened. The refrigerant enters the plate heat exchanger 1 from the compressor 2 through the second four-way valve 62, and then enters the condenser 4. After that, the refrigerant passes through the second four-way valve 62 and flows into the gas-liquid separator 3, and then flows back to the compressor 2.

[0073] The first four-way valve 61 and the second four-way valve 62 have four openings, namely, opening e, opening s, opening d, and opening c. When the first four-way valve is powered off and closed, the refrigerant can flow between opening e and opening s. When the second four-way valve 62 is powered off and closed, the refrigerant can flow between opening e and opening s or between opening d and opening c. When the second four-way valve 62 is opened, the refrigerant can flow between opening d and opening e or between opening c and opening s.

[0074] like Figure 2 and Figure 3 As shown, a first switch 81 is provided between the plate heat exchanger 1 and the condenser 4;

[0075] When the heat pump unit is in the second defrosting mode, the first switch 81 is turned on, and the refrigerant passes through the plate heat exchanger 1 and then flows into the condenser 4 through the first switch 81 .

[0076] A second switch 82 is provided at the condenser, and when the heat pump unit is working, the second switch is turned on.

[0077] The present invention also provides a defrost control system for a heat pump unit, the heat pump unit comprising a compressor 2, a condenser 4, an indoor unit 5, a gas-liquid separator 3, and a plate heat exchanger 1 connected to form a refrigerant circulation loop, the condenser 4 being provided with a defrost sensor 41, and the plate heat exchanger 1 being provided with a water pipeline;

[0078] The first end of the compressor 2 is connected to the first end of the condenser 4, the second end of the condenser 4 is connected to the first end of the indoor unit 5, the second end of the indoor unit 5 is connected to the first end of the gas-liquid separator 3, and the second end of the gas-liquid separator 3 is connected to the second end of the compressor 2;

[0079] The defrost control system includes:

[0080] Entering the first defrost condition determination module, which is configured to determine whether the heat pump unit meets the first defrost condition according to the condenser temperature obtained by the defrost sensor 41;

[0081] Entering the second defrost condition determination module, it is configured to determine whether the heat pump unit meets the second defrost condition according to the water channel status information of the plate heat exchanger 1.

[0082] The present invention can determine the defrost mode to be performed according to the actual conditions of the condenser 4 and the plate heat exchanger 1 during operation of the heat pump unit, thereby realizing automatic control of the defrost mode of the heat pump unit, improving the defrost efficiency of the heat pump unit, avoiding freezing and cracking of the plate heat exchanger, and improving the safety of the heat pump unit.

[0083] like Figure 2 and Figure 3 As shown, a liquid pipe stop valve 71 is further provided between the indoor unit 5 and the condenser 4, and a gas pipe stop valve 72 is further provided between the indoor unit 5 and the first four-way valve 61. When the heat pump unit operates in the first defrost mode, the liquid pipe stop valve 71 and the gas pipe stop valve 72 are opened, and when the heat pump unit operates in the second defrost mode, the liquid pipe stop valve 71 and the gas pipe stop valve 72 are closed.

[0084] The present invention provides a heat pump unit, comprising the defrost control system of the heat pump unit as described above.

[0085] The heat pump unit of the present invention has the defrost control system of the heat pump unit as described above, and thus has the beneficial effects of the defrost control system of the heat pump unit, improves the defrost efficiency of the heat pump unit, avoids the plate heat exchanger from being frozen and cracked at low temperatures, and improves the stability of the plate heat exchanger in the heat pump unit.

[0086] The working conditions of the heat pump unit are described below with reference to specific embodiments.

[0087] Figure 2 , Figure 3 and Figure 4 The arrow in the middle indicates the flow direction of the refrigerant.

[0088] Embodiment 1: Figure 2 As shown, the heat pump unit operates in the first defrost mode.

[0089] The heat pump unit is in heating mode.

[0090] The module for determining the first defrosting condition uses the condenser temperature obtained by the defrosting sensor 41 to compare the condenser temperature with the set temperature. At this time, the condenser temperature is less than or equal to the set temperature of 0°C of the condenser, and the heat pump unit meets the first defrosting condition.

[0091] The module for determining the second defrosting condition uses the first temperature sensor 13 to obtain the water inlet temperature and uses the flow meter to obtain the water inlet flow at the water inlet 11. It is determined that the water inlet temperature obtained by the first temperature sensor 13 is less than or equal to the set water inlet temperature of 10°C, and the water inlet flow at the water inlet 11 is less than or equal to the set water inlet flow. The heat pump unit meets the second defrosting condition.

[0092] The defrost control system of the heat pump unit controls the heat pump unit to enter the first defrost mode;

[0093] Control the first switch to be closed, the first four-way valve to be powered off and closed, the second four-way valve to be powered off and closed, and the liquid pipe stop valve 71 and the gas pipe stop valve 72 to be opened, and the indoor unit to be turned on;

[0094] At this time, the flow path of the refrigerant is:

[0095] The high-temperature refrigerant in the compressor 2 flows through the d opening and the c opening of the second four-way valve 62 and enters the condenser 4 for defrosting, and then the refrigerant flows through the liquid pipe stop valve 71 and enters the indoor unit 5, and then passes through the gas pipe stop valve 72 and through the e opening and s opening of the first four-way valve 61, and then enters the gas-liquid separator 3 and flows into the compressor 2.

[0096] Embodiment 2: Figure 3 As shown, the heat pump unit operates in the second defrost mode.

[0097] The heat pump unit is in heating mode.

[0098] The module for determining the first defrosting condition uses the condenser temperature obtained by the defrosting sensor 41 to compare the condenser temperature with the set temperature. At this time, the condenser temperature is less than or equal to the set temperature of 0°C of the condenser, and the heat pump unit meets the first defrosting condition.

[0099] Enter the second defrost condition determination module to obtain the water inlet temperature using the first temperature sensor 13 and the water inlet flow rate at the water inlet 11 using the flow meter.

[0100] It is determined that the water inlet temperature obtained by the first temperature sensor 13 is less than or equal to the set water inlet temperature of 10°C, and it is determined that the water inlet flow rate at the water inlet 11 is greater than the set water inlet flow rate, and the heat pump unit does not meet the second defrost condition; or, it is determined that the water inlet temperature obtained by the first temperature sensor 13 is greater than the set water inlet temperature of 10°C, and it is determined that the water inlet flow rate at the water inlet 11 is less than or equal to the set water inlet flow rate, and the heat pump unit does not meet the second defrost condition;

[0101] The defrost control system of the heat pump unit controls the heat pump unit to enter the second defrost mode;

[0102] The first switch is controlled to be turned on, the first four-way valve is powered off and closed, the second four-way valve is powered off and closed, and the liquid pipe stop valve 71 and the gas pipe stop valve 72 are closed.

[0103] At this time, the flow path of the refrigerant is:

[0104] The high-temperature refrigerant in the compressor 2 flows through the d opening and the c opening of the second four-way valve 62 and enters the condenser 4 for defrosting, and then the refrigerant flows through the first switch 81 and enters the plate heat exchanger 1, and then passes through the e opening and the s opening of the second four-way valve 62 to enter the gas-liquid separator 3 and then flows into the compressor 2.

[0105] Embodiment 3: Figure 4 As shown, the heat pump unit operates in heating mode.

[0106] When the heat pump unit is running in the first defrost mode or the second defrost mode,

[0107] Enter the first defrost condition determination module and use the condenser temperature obtained by the defrost sensor 41 to compare the condenser temperature with the set defrost temperature. At this time, the condenser temperature is 15°C higher than the set defrost temperature of the condenser. Continue to determine the duration of the condenser temperature being higher than the set defrost temperature. When the duration is longer than the set duration of 1 minute;

[0108] The defrost control system of the heat pump unit controls the heat pump unit to turn off the first defrost mode or the second defrost mode and enter the heating mode;

[0109] The first switch is controlled to be turned on, the first four-way valve is powered off and closed, the second four-way valve is powered on and opened, and the liquid pipe stop valve 71 and the gas pipe stop valve 72 are closed.

[0110] At this time, the flow path of the refrigerant is:

[0111] The high-temperature refrigerant in the compressor 2 flows through the d opening and the e opening of the second four-way valve 62 into the plate heat exchanger 1, and then flows through the condenser through the first switch 81. Then the refrigerant enters the gas-liquid separator 3 through the c opening and the s opening of the second four-way valve 62, and then flows into the compressor 2.

[0112] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying 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. Without departing 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 fall within the protection scope of the present invention.

Claims

1. A defrosting control method for a heat pump unit, characterized in that: The heat pump unit includes a compressor, a condenser, an indoor unit, a gas-liquid separator, and a plate heat exchanger connected to form a refrigerant circulation loop, the condenser is provided with a defrost sensor, and the plate heat exchanger is provided with a water pipeline; The first end of the compressor is connected to the first end of the condenser, the second end of the condenser is connected to the first end of the indoor unit, the second end of the indoor unit is connected to the first end of the gas-liquid separator, and the second end of the gas-liquid separator is connected to the second end of the compressor; The defrost control method comprises: According to the condenser temperature obtained by the defrost sensor, judging whether the heat pump unit meets the first defrost condition; According to the water channel status information of the plate heat exchanger, judging whether the heat pump unit meets the second defrosting condition; When the heat pump unit satisfies both the first defrost condition and the second defrost condition, controlling the heat pump unit to enter the first defrost mode; When the heat pump unit meets the first defrost condition but does not meet the second defrost condition, the heat pump unit is controlled to enter the second defrost mode.

2. The defrosting control method of a heat pump unit according to claim 1, characterized in that: Judging whether the heat pump unit meets the first defrosting condition according to the condenser temperature obtained by the defrost sensor, including: a condenser temperature obtained according to the defrost sensor; comparing the condenser temperature with a set temperature; When the condenser temperature is less than or equal to the set temperature of the condenser, it is determined that the heat pump unit meets the first defrosting condition.

3. The defrosting control method of a heat pump unit according to claim 1, characterized in that: The plate heat exchanger is provided with a water inlet and a water outlet, the water inlet is provided with a first temperature sensor and a flow meter, the water circuit state information includes the water inlet temperature and the water inlet flow rate, and judging whether the heat pump unit meets the second defrosting condition according to the water circuit state information of the plate heat exchanger includes: Determining whether the water inlet temperature acquired by the first temperature sensor is less than or equal to the set water inlet temperature; If yes, continue to determine whether the water inlet flow rate at the water inlet obtained by the flow meter is less than or equal to the set water inlet flow rate, If so, it is determined that the heat pump unit meets the second defrosting condition.

4. The defrosting control method of a heat pump unit according to claim 3, characterized in that: The set water inlet temperature is 5°C to 30°C.

5. The defrosting control method of a heat pump unit according to claim 3, characterized in that: The set flow rate is 10% to 30% of the maximum flow rates of the water inlet and the water outlet.

6. The defrosting control method of a heat pump unit according to claim 1, characterized in that: Also includes: When the heat pump unit is in the first defrost mode or the second defrost mode, it is determined whether the condenser temperature obtained by the defrost sensor is greater than or equal to a set defrost temperature. If so, continue to determine the duration of the condenser temperature being greater than the set defrost temperature. When the duration is greater than the set duration, turn off the first defrost mode or the second defrost mode of the heat pump unit and enter the heating mode.

7. The defrost control method for a heat pump unit according to any one of claims 1 to 6, characterized in that: The heat pump unit further includes a first four-way valve and a second four-way valve, wherein the first four-way valve is arranged between the indoor unit, the gas-liquid separator and the compressor, and the second four-way valve is arranged between the compressor, the condenser and the plate heat exchanger; When the heat pump unit is in the first defrost mode, the first four-way valve is de-energized and the second four-way valve is de-energized, the refrigerant passes through the second four-way valve from the compressor and enters the condenser, and then enters the indoor unit, and then the refrigerant passes through the first four-way valve and flows into the gas-liquid separator, and then flows back to the compressor; When the heat pump unit is in the second defrost mode, the first four-way valve is powered off and the second four-way valve is opened, and the refrigerant enters the plate heat exchanger from the compressor through the second four-way valve, and then enters the condenser. After that, the refrigerant passes through the second four-way valve and flows into the gas-liquid separator, and then flows back to the compressor.

8. The defrosting control method of a heat pump unit according to claim 7, characterized in that: A first switch is provided between the plate heat exchanger and the condenser; When the heat pump unit is in the second defrost mode, the first switch is turned on, and the refrigerant passes through the plate heat exchanger and then flows into the condenser through the first switch.

9. A defrost control system for a heat pump unit, characterized in that: The heat pump unit includes a compressor, a condenser, an indoor unit, a gas-liquid separator, and a plate heat exchanger connected to form a refrigerant circulation loop, the condenser is provided with a defrost sensor, and the plate heat exchanger is provided with a water pipeline; The first end of the compressor is connected to the first end of the condenser, the second end of the condenser is connected to the first end of the indoor unit, the second end of the indoor unit is connected to the first end of the gas-liquid separator, and the second end of the gas-liquid separator is connected to the second end of the compressor; The defrost control system comprises: Entering a first defrost condition determination module, which is configured to determine whether the heat pump unit meets the first defrost condition according to the condenser temperature obtained by the defrost sensor; A second defrost condition determination module is entered, which is configured to determine whether the heat pump unit meets the second defrost condition according to the water channel status information of the plate heat exchanger.

10. A heat pump unit, characterized in that: It comprises the defrost control system of the heat pump unit as claimed in claim 9.

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