Heat pump system safety protection method based on water flow detection

Abstract

The heat pump system safety protection method based on water flow detection comprises the steps that when it is determined that water flow between a water inlet end and a water outlet end is in an initial non-flowing state, a compressor is controlled to operate at a first frequency for a first set duration; acquiring a first temperature of a preset end; the first temperature is the temperature of the preset end after the compressor operates at the first frequency for a first set duration; the preset end is a water inlet end or a water outlet end; when the absolute value of the difference value between the second temperature and the first temperature is smaller than the first temperature difference threshold value, the average value of the environment temperature of the environment where the heat pump system is located within the second set duration is obtained; the second temperature is the temperature of the preset end before the compressor operates at the first frequency; and when the average value of the environment temperature is smaller than or equal to the temperature threshold value, the heat pump system is controlled to enter a defrosting protection stage, so that ice is effectively removed when the unit is iced and blocked, and safe and stable operation of the heat pump system is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of heat pump systems, and in particular to a heat pump system safety protection method based on water flow detection. Background Art

[0002] The heat pump system has been rapidly developed due to its advantages of energy saving, environmental protection, safe and stable operation. During the operation of the heat pump system that uses water for heat exchange, under low temperature conditions, the water circuit of the heat pump system may freeze or become blocked, which may cause the heat exchanger pipes of the heat pump system to burst and the whole unit to be scrapped. Summary of the invention

[0003] The present invention provides a heat pump system safety protection method based on water flow detection, which can effectively remove ice when ice blockage occurs in the unit, thereby ensuring safe and stable operation of the heat pump system.

[0004] According to one aspect of the present invention, a safety protection method for a heat pump system based on water flow detection is provided, wherein the heat pump system comprises a compressor, a four-way valve, a condenser, a heat exchanger and a water pump; the output end of the compressor is connected to the first end of the four-way valve, the second end of the four-way valve is connected to the first end of the condenser, the second end of the condenser is connected to the first end of the heat exchanger, the second end of the heat exchanger is connected to the third end of the four-way valve, and the fourth end of the four-way valve is connected to the input end of the compressor; the condenser also includes a water inlet end and a water outlet end, the water pump is arranged on a pipeline connected to the water inlet end, the first end and the second end of the condenser are connected, and the water inlet end and the water outlet end are connected; when the heat pump system is in a heating mode, the first end and the second end of the four-way valve are connected, and the third end and the fourth end are connected, and when the heat pump system is in a cooling mode, the first end and the third end of the four-way valve are connected, and the second end and the fourth end are connected;

[0005] The heat pump system safety protection method based on water flow detection includes:

[0006] When it is determined that the water flow between the water inlet and the water outlet is in a preliminary no-flow state, controlling the compressor to operate at a first frequency for a first set time period;

[0007] Acquire a first temperature of a preset end; the first temperature is the temperature of the preset end after the compressor runs at a first frequency for a first set time; wherein the preset end is the water inlet end or the water outlet end;

[0008] When the absolute value of the difference between the second temperature and the first temperature is less than the first temperature difference threshold, obtaining the average value of the ambient temperature of the environment in which the heat pump system is located within a second set time period; the second temperature is the temperature of the preset end before the compressor runs at the first frequency;

[0009] When the average value of the ambient temperature is less than or equal to the temperature threshold, the heat pump system is controlled to enter a defrost protection stage; in the defrost protection stage, the heat pump system is in a heating mode.

[0010] Optionally, before determining that the water flow between the water inlet and the water outlet is in a preliminary no-flow state, the method further includes:

[0011] After receiving the start-up instruction of the heat pump system, the water pump is controlled to start, and the heat pump system is controlled to enter the water flow detection stage;

[0012] The water flow detection stage includes:

[0013] Acquire a fourth temperature of the preset end; the fourth temperature is the temperature of the preset end after the water pump is started;

[0014] Determining the flow state of the water flow according to the difference between the third temperature and the fourth temperature of the preset end; the third temperature is the temperature of the preset end before the water pump is started;

[0015] When the absolute value of the difference between the third temperature and the fourth temperature is less than a second temperature difference threshold, it is determined that the water flow is in a preliminary no-flow state.

[0016] Optionally, the heat pump system safety protection method based on water flow detection further includes:

[0017] When the absolute value of the difference between the second temperature of the compressor and the first temperature is greater than or equal to the first temperature difference threshold, determining that the water flow is in a flowing state, and controlling the heat pump system to enter a mode determination stage;

[0018] The mode determination stage includes:

[0019] When the default mode of the heat pump system is the preset mode, when the difference between the temperature at the water inlet and the temperature at the water outlet does not meet the preset condition, the heat pump system is controlled to enter the mode protection stage; in the mode protection stage, the four-way valve is in the preset mode; the preset mode is the cooling mode or the heating mode.

[0020] Optionally, the preset mode is the cooling mode, and the preset condition is greater than or equal to the second temperature difference threshold;

[0021] The mode protection stage includes:

[0022] Turn off the water pump;

[0023] Controlling the compressor to operate at a third frequency for a sixth set time period;

[0024] Controlling the four-way valve to switch to the cooling mode;

[0025] Restart the water pump.

[0026] Optionally, the preset mode is the heating mode, and the preset condition is less than the second temperature difference threshold;

[0027] The mode protection stage includes:

[0028] Controlling the compressor to operate at a fourth frequency for a seventh set time period;

[0029] The four-way valve is controlled to switch to the heating mode.

[0030] Optionally, after the mode protection phase ends, it also includes:

[0031] The mode judgment stage is re-executed. When the difference between the temperature at the water inlet and the temperature at the water outlet meets the preset condition, the heat pump system is controlled to operate in a default mode. When the difference between the temperature at the water inlet and the temperature at the water outlet does not meet the preset condition, the heat pump system is controlled to shut down and output a fault alarm signal.

[0032] Optionally, the heat pump system safety protection method based on water flow detection further includes:

[0033] When the absolute value of the difference between the third temperature and the fourth temperature is greater than or equal to the second temperature difference threshold, it is determined that the water flow is in a flowing state, and the heat pump system is controlled to enter the mode determination stage.

[0034] Optionally, the defrost protection stage includes:

[0035] Controlling the compressor to operate at a second frequency for a third set time period;

[0036] Controlling the four-way valve to switch to the heating mode;

[0037] Control the compressor to operate at the second frequency for a fourth set time or stop after the heat pump system issues a defrost end alarm signal;

[0038] After controlling the heat pump system to enter the defrost protection stage, the method further includes:

[0039] After the defrost protection stage ends, the heat pump system is controlled to re-enter the water flow detection stage.

[0040] Optionally, before controlling the heat pump system to enter the defrost protection stage, the method further includes:

[0041] When the number of times the heat pump system enters the defrost protection stage within the fifth set time period is less than 1, controlling the heat pump system to enter the defrost protection stage;

[0042] When the number of times the heat pump system enters the defrost protection stage within the fifth set time period is greater than or equal to 1 time, the heat pump system is controlled to shut down and a fault alarm signal is output.

[0043] Optionally, the heat pump system safety protection method based on water flow detection further includes:

[0044] When the average value of the ambient temperature is greater than the temperature threshold, the heat pump system is controlled to shut down and a fault alarm signal is output.

[0045] The technical solution of the embodiment of the present invention, when it is preliminarily determined that there is no water flowing in the heat pump system, takes into account that the water in the pipes of the heat pump system may freeze due to excessively low temperature. Therefore, when the average value of the ambient temperature is less than or equal to the temperature threshold, that is, when the ambient temperature of the heat pump system is low, the four-way valve is controlled to forcibly switch so that the heat pump system is in heating mode, thereby unfreezing the heat exchanger, and protecting the heat pump system based on the result of water flow detection to ensure safe and stable operation of the system.

[0046] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 A flow chart of a heat pump system safety protection method based on water flow detection provided by an embodiment of the present invention;

[0049] Figure 2 A schematic structural diagram of a heat pump system provided by an embodiment of the present invention;

[0050] Figure 3 A flow chart of another heat pump system safety protection method based on water flow detection provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0053] Figure 1 A flow chart of a heat pump system safety protection method based on water flow detection provided in an embodiment of the present invention. This embodiment can be applied to determine whether a heat exchanger is frozen and enters de-icing protection. The method can be executed by a controller in the heat pump system. The controller can be implemented in the form of hardware and / or software, and the controller can be configured in the heat pump system. Figure 2 A schematic structural diagram of a heat pump system provided in an embodiment of the present invention, the heat pump system comprises: a compressor 1, a four-way valve 2, a condenser 3, a heat exchanger 4 and a water pump; the output end of the compressor 1 is connected to the first end A1 of the four-way valve 2, the second end A2 of the four-way valve 2 is connected to the first end B1 of the condenser 3, the second end B2 of the condenser 3 is connected to the first end of the heat exchanger 4, the second end of the heat exchanger 4 is connected to the third end A3 of the four-way valve 2, and the fourth end A4 of the four-way valve 2 is connected to the input end of the compressor 1; the condenser 3 also comprises an inlet The water end B3 and the water outlet end B4, the water pump is set on the pipeline 5 connected to the water inlet end B3, the first end B1 and the second end B2 of the condenser 3 are connected, and the water inlet end B3 and the water outlet end B4 are connected; when the heat pump system is in the heating mode, the first end A1 and the second end A2 of the four-way valve 2 are connected, and the third end A3 of the four-way valve 2 and the fourth end A4 of the four-way valve 2 are connected; when the heat pump system is in the cooling mode, the first end A1 and the third end A3 of the four-way valve 2 are connected, and the second end A2 of the four-way valve 2 and the fourth end A4 of the four-way valve 2 are connected. An electronic expansion valve 6 is also connected between the first end of the heat exchanger 4 and the second end B2 of the condenser 3.

[0054] refer to Figure 1 and Figure 2 , the method comprising:

[0055] S110: When it is determined that the water flow between the water inlet end B3 and the water outlet end B4 is in a preliminary no-flow state, the compressor 1 is controlled to operate at a first frequency for a first set time period.

[0056] First, a water flow detection is performed on the heat pump system to determine the state of the water flow in the heat pump system. In an optional embodiment, the water flow detection can determine whether there is water flow in the heat pump system based on the temperature change of the water inlet B3 or the water outlet B4 over a period of time. The preliminary no-flow state indicates that there is no water flow. After determining that there is no water flow, the compressor 1 is controlled to run at a first frequency such as 30Hz for a first set time such as 10s. Among them, the first frequency and the first set time can be set according to actual conditions.

[0057] S120: Obtaining a first temperature of a preset end. The first temperature is the temperature of the preset end after the compressor 1 runs at a first frequency for a first set time, wherein the preset end is a water inlet end or a water outlet end.

[0058] The water inlet B3 is provided with a temperature sensor to obtain the temperature of the water inlet B3, and the water outlet B4 is provided with a temperature sensor to obtain the temperature of the water outlet B4. Any one of the water inlet B3 and the water outlet B4 is used as a preset end. When the compressor 1 runs at a first frequency for a first set time, the temperature of the preset end at this time is obtained by the corresponding temperature sensor and used as the first temperature.

[0059] S130: When the absolute value of the difference between the second temperature and the first temperature is less than the first temperature difference threshold, obtain the average value of the ambient temperature of the environment in which the heat pump system is located within a second set time period; the second temperature is the temperature of the preset end before the compressor runs at the first frequency.

[0060] After receiving the start command, the compressor will start. Within a preset time, such as 10 seconds, before the compressor runs at the first frequency, the temperature of the preset end is obtained and used as the second temperature. The preset time cannot be too long to avoid the temperature of the preset end being collected too early before the compressor 1 is started, resulting in a subsequent temperature change at the preset end, which in turn reduces the accuracy of the subsequent judgment based on the difference between the first temperature and the second temperature.

[0061] The first temperature difference threshold is the minimum temperature difference that characterizes the flow of water in the heat pump system after the compressor 1 is started, such as 0.5°C. If after the compressor 1 is started, the absolute value of the difference between the second temperature at the preset end and the first temperature is less than the first temperature difference threshold, it is determined that the water flow in the heat pump system is in a no-flow state, wherein the no-flow state is used to characterize the no-flow of water. After the water pump is started, the water flow should be in a flowing state. If it is in a no-flow state, it is necessary to further determine whether the ambient temperature is too low to cause ice to form, causing the no-flow of water. Therefore, it is necessary to further obtain the average value of the ambient temperature of the environment in which the heat pump system is located. Among them, a temperature sensor can be set within the setting range of the heat pump system to characterize the temperature of the environment in which the heat pump system is located.

[0062] S140: When the average value of the ambient temperature is less than or equal to the temperature threshold, the heat pump system is controlled to enter a defrost protection stage; in the defrost protection stage, the heat pump system is in a heating mode.

[0063] The temperature threshold is the maximum value of the ambient temperature when the water flow is frozen. The temperature threshold can be 0°C. When the ambient temperature is less than or equal to 0°C, the water flow may be frozen. Therefore, the heat pump system is protected and the four-way valve 2 is controlled to be in the heat exchange mode, so that the heat pump system enters the heating mode, so that the hot air enters the condenser 3 and exchanges heat with the water inlet B3 and the water outlet B4, and performs ice melting operation to avoid the heat pump system from rupturing the pipeline due to ice.

[0064] When the average value of the ambient temperature is greater than the temperature threshold, it indicates that the possibility of water freezing in the heat pump system is low. In this case, the water flow is not likely to be blocked due to freezing. The water flow may be blocked due to failure to start the heat pump. In this case, the heat pump system is controlled to shut down for troubleshooting.

[0065] The technical solution of the embodiment of the present invention, when it is preliminarily determined that there is no water flowing in the heat pump system, takes into account that the water in the pipes of the heat pump system may freeze due to excessively low temperature. Therefore, when the average value of the ambient temperature is less than or equal to the temperature threshold, that is, when the ambient temperature of the heat pump system is low, the four-way valve is controlled to forcibly switch so that the heat pump system is in heating mode, thereby unfreezing the heat exchanger, and protecting the heat pump system based on the result of water flow detection to ensure safe and stable operation of the system.

[0066] Figure 3 A flowchart of another heat pump system safety protection method based on water flow detection provided by an embodiment of the present invention, referring to Figure 2 and Figure 3 , optionally, the method includes:

[0067] S111: After receiving the start-up instruction of the heat pump system, the water pump is controlled to start.

[0068] After receiving the start-up instruction of the heat pump system, the water pump is controlled to start, and then the heat pump system is controlled to enter the water flow detection stage. The water flow detection stage includes S121-141. The water flow detection stage is used to determine the flow state of the water flow of the heat pump system according to the temperature change of the preset end before and after the water pump is started. The flow state of the water flow includes a no-flow state, a preliminary no-flow state and a flow state, wherein the no-flow state and the preliminary no-flow state are both used to characterize the no-flow of the water flow, and the flow state characterizes the existence of the flow of the water flow.

[0069] S121: Obtaining a fourth temperature of the preset end. The fourth temperature is the temperature of the preset end after the water pump is started.

[0070] The temperature of the preset end after the water pump is started is obtained by a temperature sensor arranged at the preset end. Further, the temperature of the preset end after the water pump is started can be obtained as the fourth temperature after the water pump is started for an eighth set time, such as 10 seconds.

[0071] S131: Determine whether the absolute value of the first difference is less than the second temperature difference threshold; if so, determine that the water flow is in a preliminary non-flow state and execute S141; if not, execute S161. The first difference is the difference between the third temperature and the fourth temperature.

[0072] The flow state of the water flow is determined according to the difference between the third temperature and the fourth temperature of the preset end; the third temperature is the temperature of the preset end before the water pump is started. Within the ninth set time period before the water pump is started, such as 9 seconds, the temperature of the preset end is obtained and used as the third temperature. The second temperature difference threshold is the minimum value of the temperature change of the preset end before and after the water pump is started when the water flow is present.

[0073] When the absolute value of the difference between the third temperature and the fourth temperature is less than the second temperature difference threshold, it is determined that the water flow is in a preliminary no-flow state, and it is preliminarily determined that the water flow in the heat pump system is no-flowing.

[0074] When the absolute value of the difference between the third temperature and the fourth temperature is greater than or equal to the second temperature difference threshold, it indicates that the temperature of the preset end has changed, the water flow is determined to be in a flowing state, and the heat pump system is controlled to enter the mode judgment stage, that is, S161.

[0075] S141: Controlling the compressor 1 to operate at a first frequency for a first set time period.

[0076] S151: Determine whether the absolute value of the second difference is greater than or equal to the first temperature difference threshold, if so, execute S161, if not, execute S211. The second difference is the difference between the second temperature and the first temperature.

[0077] Before determining that the water flow is in a preliminary no-flow state and the compressor is running at the first frequency, the temperature of the preset end before the compressor 1 is running at the first frequency is obtained and used as the second temperature. After the compressor 1 is running at the first frequency for a first set time, the temperature of the preset end is obtained and used as the first temperature.

[0078] When the absolute value of the difference between the second temperature at the preset end and the first temperature is greater than or equal to the first temperature difference threshold, it is determined that the water flow is in a flowing state, and the heat pump system is controlled to enter the mode determination stage, namely S161.

[0079] S161: When the default mode of the heat pump system is the preset mode, determine whether the difference between the temperature of the water inlet and the temperature of the water outlet meets the preset condition, if not, execute S171. If yes, execute S201.

[0080] When the default mode of the heat pump system is the preset mode, when the difference between the temperature at the water inlet and the temperature at the water outlet does not meet the preset conditions, the heat pump system is controlled to enter the mode protection stage; in the mode protection stage, the four-way valve 2 is in the preset mode; the preset mode is the cooling mode or the heating mode. When the preset mode is the heating mode or the cooling mode, the corresponding preset conditions are different. When the difference between the temperature at the water inlet and the temperature at the water outlet does not meet the preset conditions, it indicates that the changes in the temperature at the water inlet and the temperature at the water outlet do not meet the preset mode of the heat pump system. The reason for this situation may be that when the four-way valve is switched to the preset mode through pressure, the switching fails. At this time, the four-way valve is controlled by high pressure and other measures to force the switch to the preset mode.

[0081] S171: Control the heat pump system to enter the mode protection stage.

[0082] When the preset mode is cooling mode, the preset condition is greater than or equal to the second temperature difference threshold. In cooling mode, if the difference between the temperature at the water inlet and the temperature at the water outlet is less than the second temperature difference threshold, it indicates that the heat pump system has a cooling abnormality, and the unit enters the mode protection stage of the cooling mode.

[0083] The mode protection stage in the cooling mode includes: turning off the outdoor fan; turning off the water pump; controlling the compressor 1 to run at the third frequency for a sixth set time; controlling the four-way valve 2 to switch to the cooling mode; and restarting the outdoor fan and the water pump.

[0084] For example, the third frequency may be 40 Hz, and the sixth set time may be 30 seconds. After the compressor 1 is controlled to start at 40 Hz and run continuously for 30 seconds, the first end A1 and the third end A3 of the four-way valve 2 are controlled to be connected, and the second end A2 and the fourth end A4 of the four-way valve are controlled to be connected, and the four-way valve 2 is forced to switch to the cooling mode.

[0085] The preset mode is heating mode, and the preset condition is less than the second temperature difference threshold. In heating mode, if the difference between the temperature at the water inlet and the temperature at the water outlet is greater than or equal to the second temperature difference threshold, it indicates that the heat pump system has a heating abnormality, and the unit enters the mode protection stage of the heating mode.

[0086] The mode protection stage in the heating mode includes: turning off the outdoor fan; controlling the compressor 1 to operate at the fourth frequency for the seventh set time; controlling the four-way valve to switch to the heating mode; and restarting the outdoor fan.

[0087] For example, the fourth frequency may be 50 Hz, and the sixth set time may be 40 seconds. After the compressor 1 is controlled to start at 50 Hz and run continuously for 40 seconds, the first end A1 and the second end A2 of the four-way valve 2 are controlled to be connected, and the third end A3 and the fourth end A4 of the four-way valve are controlled to be connected, and the four-way valve 2 is forced to switch to the heating mode.

[0088] S181: When the default mode of the heat pump system is the preset mode, determine whether the difference between the temperature at the water inlet and the temperature at the water outlet meets the preset condition; if so, execute 191. If not, execute S201.

[0089] After the mode protection phase ends, the mode determination phase is re-executed, that is, S181 is executed.

[0090] S191: Control the heat pump system to operate in default mode.

[0091] In the case where the water does not flow due to the failure of the four-way valve 2 to switch modes due to insufficient pressure, after forcing the four-way valve to switch to the preset mode by forced high pressure, the mode judgment stage is performed again. If it is determined that the difference between the temperature at the water inlet and the temperature at the water outlet meets the preset conditions, the heat pump system is normal and the heat pump system is controlled to operate in the default mode.

[0092] S201: Control the heat pump system to shut down and output a fault alarm signal.

[0093] If the difference between the temperature at the water inlet and the temperature at the water outlet does not meet the preset conditions, it is determined that the water flow is abnormal, the heat pump system is controlled to shut down and a fault alarm signal is output.

[0094] S211: Obtaining an average value of the ambient temperature of the environment in which the heat pump system is located within a second set time period.

[0095] Specifically, the average value of the ambient temperature of the environment where the heat pump system is located within 1 hour may be obtained.

[0096] S221: Determine whether the average value of the ambient temperature of the heat pump system is less than or equal to the temperature threshold. If so, execute S231; if not, execute S201.

[0097] When the average value of the ambient temperature is greater than the temperature threshold, the flow state of the water flow is determined to be abnormal, the heat pump system is controlled to shut down, and a fault alarm signal is output.

[0098] S231: Control the heat pump system to enter the defrost protection stage.

[0099] When the average value of the ambient temperature is less than or equal to the temperature threshold, such as 0°C, turn off the outdoor fan; control the compressor 1 to run at the second frequency for the third set time; control the four-way valve 2 to switch to the heating mode; control the compressor 1 to run at the second frequency for the fourth set time or stop after the heat pump system issues a defrost end alarm signal; re-execute S121.

[0100] Exemplarily, the second frequency may be 40 Hz, the third set time may be 1 minute, and the fourth set time may be 3 minutes. After turning off the outdoor fan, the compressor 1 is controlled to run at 40 Hz for 1 minute, and then the four-way valve 2 is controlled to switch to the heating mode, and the compressor 1 is shut down after running in the heating mode for 3 minutes, or the compressor 1 is shut down after running in the heating mode and the heat pump system issues a defrost end alarm signal. When the heat pump system may not run for the fourth set time in the heating mode, the temperature of the heat pump system has reached the upper limit of ice melting, indicating that the ice has been melted, and the heat pump system will generate a defrost end alarm signal.

[0101] Optionally, before controlling the heat pump system to enter the defrost protection stage, it also includes: when the number of times the heat pump system enters the defrost protection stage within the fifth set time period is less than 1 time, controlling the heat pump system to enter the defrost protection stage; when the number of times the heat pump system enters the defrost protection stage within the fifth set time period is greater than or equal to 1 time, controlling the heat pump system to shut down and outputting a fault alarm signal.

[0102] When the average value of the ambient temperature is less than or equal to the temperature threshold, and the number of times the heat pump system enters the defrost protection stage is less than 1 time within the fifth set time period, such as 1 hour, the heat pump system is controlled to enter the defrost protection stage to ensure that the defrost protection stage is only executed once within an hour.

[0103] In this embodiment, the flow state of the water in the heat pump system is preliminarily determined by the temperature change of the preset end, and there is no need to set a water flow switch, thereby improving the reliability of the system. The flow state of the water is combined with the water temperature to determine whether the heat exchanger is blocked by ice and then determine whether to enter the ice melting protection stage to perform ice melting operations to avoid pipe bursting due to ice. And through the temperature changes of the water inlet and outlet, the forced switching control of the four-way valve is performed to avoid the failure of the four-way valve to switch due to insufficient pressure, thereby ensuring the stable operation of the unit and improving the reliability of the unit.

[0104] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0105] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat pump system safety protection method based on water flow detection, characterized in that: The heat pump system includes a compressor, a four-way valve, a condenser, a heat exchanger and a water pump; the output end of the compressor is connected to the first end of the four-way valve, the second end of the four-way valve is connected to the first end of the condenser, the second end of the condenser is connected to the first end of the heat exchanger, the second end of the heat exchanger is connected to the third end of the four-way valve, and the fourth end of the four-way valve is connected to the input end of the compressor; the condenser also includes a water inlet end and a water outlet end, the water pump is arranged on a pipeline connected to the water inlet end, the first end and the second end of the condenser are connected, and the water inlet end and the water outlet end are connected; when the heat pump system is in a heating mode, the first end and the second end of the four-way valve are connected, and the third end and the fourth end are connected, and when the heat pump system is in a cooling mode, the first end and the third end of the four-way valve are connected, and the second end and the fourth end are connected; The heat pump system safety protection method based on water flow detection includes: When it is determined that the water flow between the water inlet and the water outlet is in a preliminary no-flow state, controlling the compressor to operate at a first frequency for a first set time period; Acquire a first temperature of a preset end; the first temperature is the temperature of the preset end after the compressor runs at a first frequency for a first set time; wherein the preset end is the water inlet end or the water outlet end; When the absolute value of the difference between the second temperature and the first temperature is less than the first temperature difference threshold, obtaining the average value of the ambient temperature of the environment in which the heat pump system is located within a second set time period; the second temperature is the temperature of the preset end before the compressor runs at the first frequency; When the average value of the ambient temperature is less than or equal to the temperature threshold, the heat pump system is controlled to enter a defrost protection stage; in the defrost protection stage, the heat pump system is in a heating mode.

2. The heat pump system safety protection method based on water flow detection according to claim 1 is characterized in that: Before determining that the water flow between the water inlet and the water outlet is in a preliminary no-flow state, the method further includes: After receiving the start-up instruction of the heat pump system, the water pump is controlled to start, and the heat pump system is controlled to enter the water flow detection stage; The water flow detection stage includes: Acquire a fourth temperature of the preset end; the fourth temperature is the temperature of the preset end after the water pump is started; Determining the flow state of the water flow according to the difference between the third temperature and the fourth temperature of the preset end; the third temperature is the temperature of the preset end before the water pump is started; When the absolute value of the difference between the third temperature and the fourth temperature is less than a second temperature difference threshold, it is determined that the water flow is in a preliminary no-flow state.

3. The heat pump system safety protection method based on water flow detection according to claim 2 is characterized in that: Also includes: When the absolute value of the difference between the second temperature of the compressor and the first temperature is greater than or equal to the first temperature difference threshold, determining that the water flow is in a flowing state, and controlling the heat pump system to enter a mode determination stage; The mode determination stage includes: When the default mode of the heat pump system is the preset mode, when the difference between the temperature of the water inlet and the temperature of the water outlet does not meet the preset condition, controlling the heat pump system to enter the mode protection stage; In the mode protection stage, the four-way valve is in the preset mode; the preset mode is the cooling mode or the heating mode.

4. The heat pump system safety protection method based on water flow detection according to claim 3 is characterized in that: The preset mode is the cooling mode, and the preset condition is greater than or equal to the second temperature difference threshold; The mode protection stage includes: Turn off the water pump; Controlling the compressor to operate at a third frequency for a sixth set time period; Controlling the four-way valve to switch to the cooling mode; Restart the water pump.

5. The heat pump system safety protection method based on water flow detection according to claim 3 is characterized in that: The preset mode is the heating mode, and the preset condition is that the temperature difference is less than the second temperature difference threshold; The mode protection stage includes: Controlling the compressor to operate at a fourth frequency for a seventh set time period; The four-way valve is controlled to switch to the heating mode.

6. The heat pump system safety protection method based on water flow detection according to claim 4 or 5, characterized in that: After the mode protection phase ends, it also includes: The mode judgment stage is re-executed. When the difference between the temperature at the water inlet and the temperature at the water outlet meets the preset condition, the heat pump system is controlled to operate in a default mode. When the difference between the temperature at the water inlet and the temperature at the water outlet does not meet the preset condition, the heat pump system is controlled to shut down and output a fault alarm signal.

7. The heat pump system safety protection method based on water flow detection according to claim 6 is characterized in that: Also includes: When the absolute value of the difference between the third temperature and the fourth temperature is greater than or equal to the second temperature difference threshold, it is determined that the water flow is in a flowing state, and the heat pump system is controlled to enter the mode determination stage.

8. The heat pump system safety protection method based on water flow detection according to claim 2 is characterized in that: The defrost protection stage includes: Controlling the compressor to operate at a second frequency for a third set time period; Controlling the four-way valve to switch to the heating mode; Controlling the compressor to operate at the second frequency for a fourth set time or stopping the compressor after the heat pump system issues a defrost completion alarm signal; After controlling the heat pump system to enter the defrost protection stage, the method further includes: After the defrost protection stage ends, the heat pump system is controlled to re-enter the water flow detection stage.

9. The heat pump system safety protection method based on water flow detection according to claim 8 is characterized in that: Before controlling the heat pump system to enter the defrost protection stage, the method further includes: When the number of times the heat pump system enters the defrost protection stage within the fifth set time period is less than 1, controlling the heat pump system to enter the defrost protection stage; When the number of times the heat pump system enters the defrost protection stage within the fifth set time period is greater than or equal to 1 time, the heat pump system is controlled to shut down and a fault alarm signal is output.

10. The heat pump system safety protection method based on water flow detection according to claim 1, characterized in that: Also includes: When the average value of the ambient temperature is greater than the temperature threshold, the heat pump system is controlled to shut down and a fault alarm signal is output.

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