Water flow detection based heat pump system safety protection method

Abstract

This invention discloses a safety protection method for a heat pump system based on water flow detection, comprising: when it is determined that the water flow between the inlet and outlet is in a preliminary stagnant state, controlling the compressor to run at a first frequency for a first set duration; acquiring a first temperature at a preset end; the first temperature is the temperature of the preset end after the compressor has run at the first frequency for the first set duration; the preset end is either the inlet or the outlet; when the absolute value of the difference between the second temperature and the first temperature is less than a first temperature difference threshold, acquiring the average ambient temperature of the environment in which the heat pump system is located within a second set duration; the second temperature is the temperature of the preset end before the compressor runs at the first frequency; when the average ambient temperature is less than or equal to the temperature threshold, controlling the heat pump system to enter a defrost protection stage to effectively defrost when there is ice blockage in the unit, thereby ensuring the safe and stable operation of the heat pump system.

Description

Technical Field

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

[0002] Heat pump systems have experienced rapid development due to their advantages such as energy saving, environmental protection, and safe and stable operation. However, during the operation of heat pump systems that utilize water for heat exchange, under low-temperature conditions, the water circuits may freeze or become blocked, potentially causing the heat exchanger pipes to burst and the entire unit to become unusable. Summary of the Invention

[0003] This invention provides a safety protection method for a heat pump system based on water flow detection, which effectively removes ice when the unit is blocked by ice, ensuring the 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. 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 a first end of the four-way valve, the second end of the four-way valve is connected to a first end of the condenser, the second end of the condenser is connected to a first end of the heat exchanger, the second end of the heat exchanger is connected to a 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 an inlet end and an outlet end. The water pump is disposed on a pipe connected to the inlet end. The first and second ends of the condenser are connected, and the inlet and outlet ends are connected. When the heat pump system is in heating mode, the first and second ends of the four-way valve are connected, and the third and fourth ends are connected. When the heat pump system is in cooling mode, the first and third ends of the four-way valve are connected, and the second and fourth ends are connected.

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

[0006] When it is determined that the water flow between the inlet and the outlet is in a preliminary stagnant state, the compressor is controlled to run at a first frequency for a first set duration.

[0007] Obtain the first temperature of the 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, the average value of the ambient temperature of the environment in which the heat pump system is located within a second set time period is obtained; the second temperature is the temperature of the preset terminal before the compressor runs at the first frequency;

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

[0010] Optionally, before determining that the water flow between the inlet and the outlet is in a preliminary stagnant state, the method further includes:

[0011] Upon receiving the start command of the heat pump system, the system controls the water pump to start and controls the heat pump system to enter the water flow detection stage.

[0012] The water flow detection stage includes:

[0013] Obtain the fourth temperature of the preset end; the fourth temperature is the temperature of the preset end after the water pump is started.

[0014] The flow state of the water is determined based on the difference between the third temperature and the fourth temperature at the preset end; the third temperature is the temperature at 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 the second temperature difference threshold, the water flow is determined to be in a preliminary non-flowing state.

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

[0017] When the absolute value of the difference between the second temperature and the first temperature of the compressor 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 judgment stage.

[0018] The pattern determination stage includes:

[0019] When the default mode of the heat pump system is the preset mode, if the difference between the temperature at the inlet end and the temperature at the outlet end 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 phase includes:

[0022] Turn off the water pump;

[0023] The compressor is controlled to run at a third frequency for a sixth set duration;

[0024] Control 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 that the temperature difference is less than the second temperature difference threshold.

[0027] The mode protection phase includes:

[0028] The compressor is controlled to run at a fourth frequency for a seventh set duration;

[0029] Control the four-way valve to switch to the heating mode.

[0030] Optionally, after the mode protection phase ends, the following may also be included:

[0031] The mode determination phase is re-executed. When the difference between the temperature at the inlet and the temperature at the outlet meets the preset conditions, the heat pump system is controlled to operate in the default mode. When the difference between the temperature at the inlet and the temperature at the outlet does not meet the preset conditions, the heat pump system is controlled to stop and output a fault alarm signal.

[0032] Optionally, the safety protection method for the heat pump system 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 judgment stage.

[0034] Optionally, the defrosting protection stage includes:

[0035] The compressor is controlled to operate at a second frequency for a third set duration;

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

[0037] The compressor is stopped after it is controlled to run at a second frequency for a fourth set duration or after the heat pump system issues a defrosting end alarm signal;

[0038] After controlling the heat pump system to enter the defrost protection phase, the following is also included:

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

[0040] Optionally, before controlling the heat pump system to enter the defrost protection phase, the following steps are also included:

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

[0042] If the heat pump system enters the defrost protection stage more than or equal to once within the fifth set time period, the heat pump system will be shut down and a fault alarm signal will be output.

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

[0044] When the average ambient temperature exceeds the temperature threshold, the heat pump system is shut down and a fault alarm signal is output.

[0045] The technical solution of this invention, when initially determining that there is no water flow in the heat pump system, considers that the water in the pipes of the heat pump system may freeze due to excessively low temperature. Therefore, when the average 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 force switching so that the heat pump system is in heating mode, thereby thawing the heat exchanger. Based on the water flow detection results, the heat pump system is protected to ensure safe and stable operation of the system.

[0046] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0049] Figure 2 This is a schematic diagram of the structure of a heat pump system provided in an embodiment of the present invention;

[0050] Figure 3 A flowchart of another safety protection method for a heat pump system based on water flow detection provided in an embodiment of the present invention. Detailed Implementation

[0051] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort 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, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0053] Figure 1 The flowchart illustrates a safety protection method for a heat pump system based on water flow detection, as provided in this embodiment of the invention. This embodiment is applicable to situations where the heat exchanger is icing up and enters the defrosting protection state. This method can be executed by a controller in the heat pump system, which can be implemented in hardware and / or software and can be configured in the heat pump system. Figure 2 This is a schematic diagram of a heat pump system provided in an embodiment of the present invention. The heat pump system includes: 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 includes an inlet pump... Water inlet B3 and outlet B4 are connected. The water pump is installed on pipe 5 connected to water inlet B3. The first end B1 and the second end B2 of condenser 3 are connected, and water inlet B3 and water outlet B4 are connected. In heating mode, the first end A1 and the second end A2 of four-way valve 2 are connected, and the third end A3 and the fourth end A4 of four-way valve 2 are connected. In cooling mode, the first end A1 and the third end A3 of four-way valve 2 are connected, and the second end A2 and the fourth end A4 of four-way valve 2 are connected. An electronic expansion valve 6 is also connected between the first end of heat exchanger 4 and the second end B2 of condenser 3.

[0054] refer to Figure 1 and Figure 2 The method includes:

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

[0056] First, water flow detection is performed on the heat pump system to determine the state of water flow within the system. In one optional embodiment, water flow detection can determine whether water flow exists in the heat pump system based on the temperature change at the inlet B3 or outlet B4 over a period of time. A preliminary absence of flow indicates 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 duration, such as 10s. Both the first frequency and the first set duration can be set according to actual conditions.

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

[0058] A temperature sensor is installed at the inlet B3 to obtain the temperature of the inlet B3, and a temperature sensor is installed at the outlet B4 to obtain the temperature of the outlet B4. Either the inlet B3 or the 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 period, such as 10 seconds, before the compressor starts running at the first frequency, the temperature at a preset point is acquired and used as the second temperature. The preset time period should not be too long to avoid acquiring the temperature at the preset point too early before the compressor starts, which could lead to subsequent temperature changes at the preset point and reduce the accuracy of subsequent judgments based on the difference between the first and second temperatures.

[0061] The first temperature difference threshold is the minimum temperature difference characteristic of the water flow in the heat pump system after compressor 1 starts, such as 0.5℃. If, after compressor 1 starts, the absolute value of the difference between the preset second temperature and the first temperature is less than the first temperature difference threshold, then the water flow in the heat pump system is determined to be in a non-flowing state, where the non-flowing state is used to characterize the absence of water flow. After the water pump starts, the water flow should be in a flowing state. If it is in a non-flowing state, it is necessary to further determine whether the non-flowing water flow is caused by freezing due to excessively low ambient temperature. Therefore, it is necessary to further obtain the average value of the ambient temperature of the environment where the heat pump system is located. A temperature sensor can be installed within the set range of the heat pump system to characterize the temperature of the environment where the heat pump system is located.

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

[0063] The temperature threshold is the maximum ambient temperature that indicates the possibility of water freezing. The temperature threshold can be 0℃. When the ambient temperature is less than or equal to 0℃, water may freeze. Therefore, to ensure the safety of the heat pump system, the four-way valve 2 is controlled to be in heat exchange mode, allowing the heat pump system to enter heating mode. This allows hot air to enter the condenser 3 and exchange heat with the inlet B3 and outlet B4 to perform de-icing, preventing pipe rupture due to freezing.

[0064] When the average ambient temperature is greater than the temperature threshold, it indicates that the possibility of water freezing in the heat pump system is low. This rule out the possibility that the water is not flowing due to freezing. The water may not be flowing due to the heat pump failing to start. In this case, the heat pump system should be shut down for troubleshooting.

[0065] The technical solution of this invention, when initially determining that there is no water flow in the heat pump system, considers that the water in the pipes of the heat pump system may freeze due to excessively low temperature. Therefore, when the average 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 force switching so that the heat pump system is in heating mode, thereby thawing the heat exchanger. Based on the water flow detection results, the heat pump system is protected to ensure safe and stable operation of the system.

[0066] Figure 3 A flowchart of another safety protection method for a heat pump system based on water flow detection provided in an embodiment of the present invention is shown below. Figure 2 and Figure 3 Optionally, the method includes:

[0067] S111: After receiving the start command of the heat pump system, control the water pump to start.

[0068] Upon receiving the start command of the heat pump system, the system controls the water pump to start, and then controls the heat pump system to enter the water flow detection stage. The water flow detection stage includes steps S121-141. This stage determines the flow state of the water in the heat pump system based on the temperature change at a preset point before and after the water pump starts. The flow state includes no flow, preliminary no flow, and flow. The no flow and preliminary no flow states characterize the absence of water flow, while the flow state characterizes the presence of water flow.

[0069] S121: Obtain the fourth temperature at the preset end. The fourth temperature is the temperature at the preset end after the water pump starts.

[0070] The temperature at the preset end after the water pump starts is obtained by a temperature sensor set at the preset end. Furthermore, the temperature at the preset end after the water pump starts for an eighth set time, such as 10 seconds, can be obtained and used as the fourth temperature.

[0071] S131: Determine whether the absolute value of the first difference is less than the second temperature difference threshold; if yes, determine that the water flow is in a preliminary stagnant state and execute S141; otherwise, execute S161. The first difference is the difference between the third and fourth temperatures.

[0072] The flow state of the water is determined based on the difference between the third and fourth temperatures at the preset end; the third temperature is the temperature at the preset end before the water pump starts. Within a ninth preset time period (e.g., 9 seconds) before the water pump starts, the temperature at the preset end is acquired and used as the third temperature. The second temperature difference threshold represents the minimum temperature change at the preset end before and after the water pump starts when water flow is present.

[0073] When the absolute value of the difference between the third and fourth temperatures is less than the second temperature difference threshold, it is determined that the water flow is in a preliminary non-flowing state, and it is preliminarily determined that the water flow in the heat pump system is non-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 there is a change in the temperature at the preset end, determines that the water flow is in a flowing state, and controls the heat pump system to enter the mode judgment stage, namely S161.

[0075] S141: Control compressor 1 to run at a first frequency for a first set duration.

[0076] S151: Determine whether the absolute value of the second difference is greater than or equal to the first temperature difference threshold. If yes, execute S161; otherwise, execute S211. The second difference is the difference between the second temperature and the first temperature.

[0077] Before determining that the water flow is initially at a standstill and before the compressor operates at a first frequency, the temperature at the preset end before the compressor 1 operates at the first frequency is obtained and used as the second temperature. After the compressor 1 operates at the first frequency for a first set time, the temperature at the preset end is obtained and used as the first temperature.

[0078] When the absolute value of the difference between the second temperature and the first temperature at the preset end 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 judgment 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 at the inlet and the temperature at the outlet meets the preset conditions. If not, execute S171. If yes, execute S201.

[0080] When the default mode of the heat pump system is the preset mode, if the difference between the inlet water temperature and the outlet water temperature does not meet the preset conditions, the heat pump system enters the mode protection stage. During the mode protection stage, the four-way valve 2 is in the preset mode; the preset mode is either cooling mode or heating mode. The preset conditions for the heating mode and cooling mode are different. When the difference between the inlet water temperature and the outlet water temperature does not meet the preset conditions, it indicates that the temperature changes at the inlet and outlet water ends do not conform to the preset mode of the heat pump system. This situation may occur because the four-way valve failed to switch to the preset mode via pressure. In this case, high pressure or other measures are used to force the four-way valve to switch to the preset mode.

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

[0082] When the preset mode is cooling mode, the preset condition is that the temperature difference is greater than or equal to the second temperature difference threshold. In cooling mode, if the difference between the temperature at the inlet and the temperature at the 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 phase of cooling mode.

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

[0084] For example, the third frequency can be 40Hz, and the sixth set duration can be 30 seconds. After the compressor 1 is started at 40Hz and runs continuously for 30 seconds, the first end A1 and the third end A3 of the four-way valve 2 are connected, and the second end A2 and the fourth end A4 of the four-way valve are connected, forcibly controlling the four-way valve 2 to switch to the cooling mode.

[0085] The preset mode is heating mode, and the preset condition is that the temperature difference is less than the second temperature difference threshold. In heating mode, if the difference between the temperature at the inlet and the temperature at the 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 phase of heating mode.

[0086] The mode protection phase in heating mode includes: shutting down the outdoor fan; controlling compressor 1 to run at the fourth frequency for the seventh set duration; controlling the four-way valve to switch to heating mode; and restarting the outdoor fan.

[0087] For example, the fourth frequency can be 50Hz, and the sixth set duration can be 40 seconds. After the compressor 1 is started at 50Hz and runs continuously for 40 seconds, the first end A1 and the second end A2 of the four-way valve 2 are connected, and the third end A3 and the fourth end A4 of the four-way valve are connected, forcibly controlling the four-way valve 2 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 inlet and the temperature at the outlet meets the preset conditions; if yes, proceed to 191. If not, proceed to S201.

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

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

[0091] In the event that the water flow may stop due to insufficient pressure causing the four-way valve 2 to fail to switch modes, after forcibly switching the four-way valve to the preset mode using high pressure, a mode judgment stage is performed again. If the difference between the temperature at the inlet and the temperature at the outlet meets the preset conditions, the heat pump system is normal, and the heat pump system is controlled to work in the default mode.

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

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

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

[0095] Specifically, this can be achieved by obtaining, for example, the average ambient temperature of the environment in which the heat pump system is located within 1 hour.

[0096] S221: Determine whether the average ambient temperature of the heat pump system is less than or equal to the temperature threshold. If yes, execute S231; otherwise, execute S201.

[0097] When the average ambient temperature exceeds the temperature threshold, the system determines that the water flow is abnormal, controls the heat pump system to shut down, and outputs a fault alarm signal.

[0098] S231: Controls the heat pump system to enter the defrost protection phase.

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

[0100] For example, the second frequency can be 40Hz, the third set duration can be 1 minute, and the fourth set duration can be 3 minutes. After the outdoor fan is turned off, the compressor 1 is controlled to run at 40Hz for 1 minute, and then the four-way valve 2 is controlled to switch to heating mode. After running in heating mode for 3 minutes, the system stops, or it stops after running in heating mode and the heat pump system issues a defrost end alarm signal. It is possible that the heat pump system temperature has reached the upper limit of the defrost limit before the fourth set duration has been reached, indicating that the ice has melted. At this time, 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, the following steps are also included: if the number of times the heat pump system enters the defrost protection stage within the fifth set time period is less than 1, control the heat pump system to enter the defrost protection stage; if 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, control the heat pump system to shut down and output a fault alarm signal.

[0102] When the average 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 once 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 executed only once per hour.

[0103] In this embodiment, the flow state of water in the heat pump system is initially determined by the temperature change at a preset end, eliminating the need for a flow switch and improving system reliability. By combining the water flow state with the water temperature, it is determined whether the heat exchanger is blocked by ice, thus determining whether to initiate the ice-melting protection phase and perform ice-melting operations to prevent pipe bursts due to ice. Furthermore, the temperature changes at the inlet and outlet ends are used to force-switch the four-way valve to prevent switching failure due to insufficient pressure, ensuring stable unit operation and improving unit reliability.

[0104] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0105] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A safety protection method for a heat pump system 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 an inlet end and an outlet end. The water pump is installed on the pipeline connected to the inlet end. The first and second ends of the condenser are connected, and the inlet and outlet ends are connected. When the heat pump system is in heating mode, the first and second ends of the four-way valve are connected, and the third and fourth ends are connected. When the heat pump system is in cooling mode, the first and third ends of the four-way valve are connected, and the second and fourth ends are connected. The safety protection method for the heat pump system based on water flow detection includes: When it is determined that the water flow between the inlet and the outlet is in a preliminary stagnant state, the compressor is controlled to run at a first frequency for a first set duration. Obtain the first temperature of the 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, the average value of the ambient temperature of the environment in which the heat pump system is located within a second set time period is obtained; the second temperature is the temperature of the preset terminal before the compressor runs at the first frequency; When the average ambient temperature is less than or equal to a temperature threshold, the heat pump system is controlled to enter the defrost protection phase; during the defrost protection phase, the heat pump system is in heating mode.

2. The safety protection method for a heat pump system based on water flow detection according to claim 1, characterized in that, Before determining that the water flow between the inlet and outlet is in a preliminary stagnant state, the process also includes: Upon receiving the start command of the heat pump system, the system controls the water pump to start and controls the heat pump system to enter the water flow detection stage. The water flow detection stage includes: Obtain the fourth temperature of the preset end; the fourth temperature is the temperature of the preset end after the water pump is started. The flow state of the water is determined based on the difference between the third temperature and the fourth temperature at the preset end; the third temperature is the temperature at 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 the second temperature difference threshold, the water flow is determined to be in a preliminary non-flowing state.

3. The safety protection method for a heat pump system based on water flow detection according to claim 2, characterized in that, Also includes: When the absolute value of the difference between the second temperature and the first temperature of the compressor 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 judgment stage. The pattern determination stage includes: When the default mode of the heat pump system is the preset mode, if the difference between the temperature at the inlet and the temperature at the outlet does not meet the preset conditions, the heat pump system is controlled to enter the mode protection stage. During the mode protection phase, the four-way valve is in the preset mode; the preset mode is either the cooling mode or the heating mode.

4. The safety protection method for a heat pump system based on water flow detection according to claim 3, 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 phase includes: Turn off the water pump; The compressor is controlled to run at a third frequency for a sixth set duration; Control the four-way valve to switch to the cooling mode; Restart the water pump.

5. The safety protection method for a heat pump system based on water flow detection according to claim 3, 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 phase includes: The compressor is controlled to run at a fourth frequency for a seventh set duration; Control the four-way valve to switch to the heating mode.

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

7. The safety protection method for a heat pump system based on water flow detection according to claim 6, 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 judgment stage.

8. The safety protection method for a heat pump system based on water flow detection according to claim 2, characterized in that, The defrosting protection phase includes: The compressor is controlled to operate at a second frequency for a third set duration; Control the four-way valve to switch to the heating mode; The compressor is stopped after it is controlled to run at a second frequency for a fourth set duration or after the heat pump system issues a defrosting end alarm signal; After controlling the heat pump system to enter the defrost protection phase, the following is also included: After the defrosting protection phase ends, the heat pump system is controlled to re-enter the water flow detection phase.

9. The safety protection method for a heat pump system based on water flow detection according to claim 8, characterized in that, Before the heat pump system enters the defrost protection phase, the following also applies: If the number of times the heat pump system enters the defrost protection stage is less than 1 within the fifth set time period, the heat pump system is controlled to enter the defrost protection stage. If the heat pump system enters the defrost protection stage more than or equal to once within the fifth set time period, the heat pump system will be shut down and a fault alarm signal will be output.

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

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