Heat pump water heater control method and heat pump water heater

Abstract

The invention relates to the technical field of hot water supply equipment, and discloses a heat pump water heater control method and a heat pump water heater. If a low-voltage switch is switched off, working parameters are adjusted based on the number of times of shutdown and first duration, and a heat pump host is controlled to be restarted; the starting time of the first duration is the first-time disconnection time after the low-voltage switch is kept closed for the first preset duration or the first-time disconnection time within the first preset duration when the heat pump host is started at the current water tank temperature; if the working parameters reach the parameter threshold value, the low-voltage switch is switched off, and it is determined that the heat pump host breaks down. When the heat pump host triggers low-pressure protection, recording of the first duration is started after the temperature of the water tank is adjusted, the opening degree of the expansion valve and the temperature of the water tank are adjusted according to the recording, so that the heat pump host jumps out of low-pressure protection, and the situation that the heat pump host triggers low-pressure protection when the temperature of the water tank is too low or the opening degree of the expansion valve is too small is avoided; the water heater can work normally at the low environment temperature, and the stability and reliability of the water heater are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hot water supply equipment, and in particular to a heat pump water heater control method and a heat pump water heater. Background Art

[0002] Some existing heat pump water heaters will be equipped with electric heating in the water tank to cope with low ambient temperature heating. In order to prevent the compressor from operating at a suction pressure lower than atmospheric pressure due to refrigerant leakage or low ambient temperature, the heat pump water heater is usually equipped with a low-pressure protection device. If the low-pressure protection device is in the disconnected state, the compressor is controlled to stop running. However, when the heat pump water heater heats the cold water added to the water tank at a lower ambient temperature, the water temperature in the water tank is close to the ambient temperature at this time, and the pressure ratio of the compressor is small. If there is a slight leakage of the refrigerant or the opening of the expansion valve is too small, it is easy to trigger the low-pressure protection due to the low pressure of the system, causing the water heater to be unable to continue to work, reducing the stability and reliability of the water heater. Summary of the invention

[0003] The first technical problem solved by the present invention is to provide a heat pump water heater control method, which effectively solves the problem of low stability and reliability of the water heater under the condition of small pressure ratio of the compressor.

[0004] The second technical problem solved by the present invention is to provide a heat pump water heater, which effectively solves the problem of low working stability and reliability of the water heater under the condition of small pressure ratio of the compressor.

[0005] The first technical problem mentioned above is solved by the following technical solution:

[0006] A method for controlling a heat pump water heater, the heat pump water heater comprising a heat pump host, the method comprising:

[0007] If the low-pressure switch of the heat pump host is disconnected, the compressor is controlled to stop, the number of shutdowns and the first duration of the compressor are recorded, the working parameters are adjusted based on the number of shutdowns and the first duration, and the heat pump host is controlled to restart based on the adjusted working parameters; the working parameters include the water tank temperature and the expansion valve opening; the starting time of the first duration is the time when the low-pressure switch is first triggered to disconnect after the low-pressure switch remains closed for the first preset time during the current heating process of the heat pump water heater, or the time when the low-pressure switch is first triggered to disconnect within the first preset time when the heat pump host is started at the current water tank temperature; the end time of the first duration is the time when the low-pressure switch is most recently triggered to disconnect;

[0008] If the low-pressure switch is disconnected when the adjusted working parameter reaches the parameter threshold, it is determined that the heat pump host has a fault.

[0009] Compared with the background technology, the heat pump water heater control method of the present invention has the following beneficial effects: the time when the low-pressure switch is triggered to disconnect for the first time after the low-pressure switch remains closed for the first preset time during the current heating process of the heat pump water heater is used as the starting time of the first time, and the recording of the first time is started when the low-pressure protection is triggered after the heat pump host is operating normally or resuming normal operation, so as to adjust the expansion valve opening and the water tank temperature according to the number of shutdowns and the first time, so that the heat pump host jumps out of the low-pressure protection; during the current heating process of the heat pump water heater, at the current water tank temperature, the time when the low-pressure switch is triggered to disconnect for the first time within the first preset time when the heat pump host is started. The time of opening is used as the starting time of the first duration. When the heat pump water heater is turned on and the heat pump host is directly triggered to shut down, the record of the first duration is started, so that the expansion valve opening and the water tank temperature are adjusted according to the number of shutdowns and the first duration. When the water tank temperature is adjusted and reaches the current water tank temperature, the record of the first duration is restarted, so as to start a new round of adjustment of the expansion valve opening and the water tank temperature, so that the heat pump host jumps out of the low-pressure protection; thereby, the low-pressure protection is avoided because the heat pump host is too low in the water tank temperature or the expansion valve opening is too small, so that the water heater can work normally at a lower ambient temperature, and the working stability and reliability of the water heater are improved. At the same time, when the expansion valve opening and the water tank temperature reach the corresponding parameter threshold, the low-pressure switch is still disconnected, so that the influence of the low water tank temperature or the small expansion valve opening on the low-pressure switch can be eliminated, so that it is determined that the heat pump host has a fault and the water heater is locked to achieve fault protection of the water heater, further improving the reliability of the water heater.

[0010] In one embodiment, the heat pump water heater further includes an auxiliary heat source, which is used to heat the water tank. Based on the number of shutdowns and the first duration, the operating parameters are adjusted, including:

[0011] If the number of shutdowns is less than the preset number of times, and the first duration is less than the second preset duration, the opening of the expansion valve is adjusted to increase the opening of the expansion valve;

[0012] If the adjusted expansion valve opening reaches the opening threshold, the auxiliary heat source is controlled to adjust the water tank temperature based on the relationship between the water tank temperature and the temperature threshold, and the expansion valve opening is adjusted to the initial opening.

[0013] In one embodiment, the heat pump water heater further includes an auxiliary heat source, which is used to heat the water tank. Based on the number of shutdowns and the first duration, the operating parameters are adjusted, including:

[0014] If the number of shutdowns is greater than the preset number and the first duration is less than the second preset duration, the auxiliary heat source is controlled to operate to adjust the water tank temperature based on the relationship between the water tank temperature and the temperature threshold.

[0015] In one embodiment, if the adjusted expansion valve opening does not reach the opening threshold, the heat pump host is controlled to restart based on the adjusted working parameters, including:

[0016] Restart the heat pump host;

[0017] Based on the adjusted expansion valve opening, the operation of the heat pump host is controlled.

[0018] In one embodiment, after the adjusted working parameters are used to control the heat pump host to restart, the process further includes:

[0019] If the low-pressure switch is disconnected within the first preset time after the heat pump host is restarted, the number of shutdowns is cumulatively updated, and the first time is updated based on the disconnection time of the low-pressure switch.

[0020] In one embodiment, if the adjusted expansion valve opening reaches the opening threshold, the heat pump host is controlled to restart based on the adjusted working parameters, including:

[0021] Restart the heat pump host;

[0022] Based on the initial opening and the adjusted water tank temperature, the operation of the heat pump host is controlled.

[0023] In one embodiment, if the number of shutdowns is greater than a preset number and the first duration is less than a preset duration, the heat pump host is controlled to restart based on the adjusted working parameters, including:

[0024] Restart the heat pump host;

[0025] Based on the adjusted water tank temperature, the heat pump host is controlled to operate.

[0026] In one embodiment, if the water tank temperature is adjusted, then based on the adjusted working parameters, after controlling the heat pump host to restart, the method further includes:

[0027] First, the number of shutdown times and the first duration are cleared to zero, and then it is determined whether the low-pressure switch is closed within the first preset time after the heat pump host is restarted.

[0028] In one embodiment, after controlling the heat pump host to restart based on the adjusted working parameters, the method further includes:

[0029] If the low-pressure switch remains closed, it is determined that the heat pump host is operating normally, and the number of shutdowns and the first duration are reset to zero.

[0030] The above second technical problem is solved by the following technical solution:

[0031] A heat pump water heater comprises a controller, wherein the controller is used to execute any of the heat pump water heater control methods described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 is a flow chart of a heat pump water heater control method according to an embodiment of the present invention;

[0034] Figure 2 It is a schematic diagram of a flow chart of adjusting working parameters in a heat pump water heater control method according to an embodiment of the present invention;

[0035] Figure 3 It is a flow chart of controlling the restart of the heat pump host when the adjusted working parameter in a heat pump water heater control method according to an embodiment of the present invention is the expansion valve opening and the adjusted expansion valve opening does not reach the opening threshold;

[0036] Figure 4 It is a flow chart of controlling the restart of a heat pump host when the adjusted working parameter is the water tank temperature in a heat pump water heater control method according to an embodiment of the present invention;

[0037] Figure 5 It is a flow chart of controlling the restart of a heat pump host when the adjusted working parameters in a heat pump water heater control method according to an embodiment of the present invention are the expansion valve opening and the water tank temperature;

[0038] Figure 6 It is a flow chart of a specific implementation of a heat pump water heater control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0042] In the description of this application, it should be noted that, 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 ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] As described in the background technology, at present, when the ambient temperature of the heat pump water heater is low and the pressure ratio of the compressor is small, if there is a slight leakage of the refrigerant or the opening of the expansion valve is small, the low pressure of the system may easily trigger the low pressure protection, causing the water heater to be unable to continue working, reducing the stability and reliability of the heat pump water heater.

[0044] Based on this, the present invention provides a heat pump water heater control method, which takes the time when the low-pressure switch is triggered to disconnect for the first time after being closed for a first preset time during the current heating process of the heat pump water heater as the starting time of the first time, and starts recording the first time when the low-pressure protection is triggered after the heat pump host is operating normally or resumes normal operation, so that the expansion valve opening and the water tank temperature are adjusted according to the number of shutdowns and the first time, so that the heat pump host jumps out of the low-pressure protection; takes the time when the low-pressure switch is triggered to disconnect for the first time within the first preset time when the heat pump host is started at the current water tank temperature during the current heating process of the heat pump water heater as the starting time of the first time, and starts recording the first time when the heat pump host is directly triggered to shut down after the heat pump water heater is turned on, so that the expansion valve opening and the water tank temperature are adjusted according to the number of shutdowns and the first time, so that the heat pump host jumps out of the low-pressure protection. After a certain period of time, the expansion valve opening and the water tank temperature are adjusted. When the water tank temperature is adjusted and reaches the current water tank temperature, the recording of the first period of time is restarted, thereby starting a new round of adjustment of the expansion valve opening and the water tank temperature, so that the heat pump host can jump out of the low-pressure protection; thereby, avoiding the low-pressure protection caused by the heat pump host when the water tank temperature is too low or the expansion valve opening is too small, so that the water heater can work normally at a lower ambient temperature, and the working stability and reliability of the water heater are improved; at the same time, when the expansion valve opening and the water tank temperature reach the corresponding parameter thresholds, the low-pressure switch is still disconnected, then the influence of the low water tank temperature or the small expansion valve opening on the low-pressure switch can be eliminated, thereby determining that the heat pump host has a fault and locking the water heater, thereby realizing fault protection for the water heater and further improving the reliability of the water heater.

[0045] Combine the following Figures 1 to 6 , describing an embodiment of the present invention.

[0046] According to an embodiment of the present invention, on the one hand, a heat pump water heater control method is provided, which can be applied to a heat pump water heater; wherein the heat pump water heater includes a heat pump main unit and an auxiliary heat source, and both the heat pump main unit and the auxiliary heat source are used to heat a water tank. Figure 1 is a flow chart of a water heater control method according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0047] Step 110: If the low-pressure switch of the heat pump host is disconnected, the compressor is controlled to shut down, the number of shutdowns and the first duration of the compressor are recorded, and based on the number of shutdowns and the first duration, the working parameters are adjusted, and based on the adjusted working parameters, the heat pump host is controlled to restart.

[0048] In the embodiment of the present invention, if the low-pressure switch of the heat pump host is disconnected, it indicates that the heat pump host has triggered the low-pressure protection and shut down. At this time, the low-pressure protection may be triggered due to refrigerant leakage or too low ambient temperature, that is, the low-pressure protection is triggered due to a failure of the heat pump host or the current working environment is not suitable; it may also be triggered due to the water temperature of the water tank being close to the ambient temperature, the refrigerant has a slight leakage or the initial opening of the expansion valve is set too small, that is, the low-pressure protection is triggered by mistake due to inappropriate related settings of the heat pump host. In order to avoid the latter mistakenly touching the low-pressure protection and causing the water heater to be unusable, the working parameters of the heat pump host are adjusted. On the one hand, the triggering cause of the low-pressure protection is determined, and on the other hand, when the low-pressure protection is mistakenly touched, the heat pump host can be adjusted to appropriate working parameters to make the heat pump host work normally.

[0049] In the embodiment of the present invention, when the low-pressure switch is disconnected, the heat pump host in the heat pump water heater shuts down, and the compressor of the heat pump host shuts down accordingly, but the heat pump water heater is not powered off, so the number of compressor shutdowns is recorded to determine the total number of shutdowns of the current heat pump host.

[0050] In the embodiment of the present invention, when the low-pressure switch is disconnected, the first duration is recorded at the same time. The starting time of the first duration is the time when the low-pressure switch is triggered to disconnect for the first time after the low-pressure switch remains closed for the first preset time during the current heating process of the heat pump water heater, or the time when the low-pressure switch is triggered to disconnect for the first time within the first preset time when the heat pump host is started at the current water tank temperature; the end time of the first duration is the time when the low-pressure switch is most recently triggered to disconnect. Among them, the current heating process of the heat pump water heater refers to the current working process of the heat pump water heater. If the heat pump water heater is not powered off but is in standby mode, it is considered that it is not in the current heating process of the heat pump water heater at this time, that is, each time the heat pump water heater switches from standby mode to heating mode, the recording of the number of shutdowns and the first duration is restarted. The low-pressure switch remains closed for the first preset time, indicating that the heat pump host is operating normally or has resumed normal operation after adjustment. The time when the low-pressure switch is first triggered to open after the low-pressure switch remains closed for the first preset time is used as the starting time of the first time, so that when the heat pump host stops during normal operation, the relevant adjustment of the working parameters of the heat pump host is started, so that the heat pump host can jump out of the low-pressure protection by adjusting the working parameters. At the current water tank temperature, the low-pressure switch is triggered for the first time within the first preset time when the heat pump host is started, indicating that the heat pump host is directly shut down after starting. At this time, there are two situations: In the first situation, the current water tank temperature has not been adjusted. At this time, the heat pump host is initially started, indicating that the heat pump host is directly shut down after the heat pump water heater is turned on. Therefore, this time is used as the starting time of the first time, and the relevant adjustment of the working parameters of the heat pump host is started, so that the heat pump host can jump out of the low-pressure protection by adjusting the working parameters. In the second case, the water tank temperature is adjusted to the current water tank temperature, that is, the heat pump host was previously shut down, and the working parameters are being adjusted to restore the heat pump host to normal operation; because the heat pump host needs to be restarted after the working parameters are adjusted, it means that the heat pump host is shut down again after restarting, and the working parameters need to be adjusted further, so the first duration needs to be recorded, but at the same time, because the water tank temperature has changed, the working environment of the heat pump host has changed, and the current water tank temperature needs to be used as the new benchmark for adjusting the expansion valve opening, so the first duration needs to be reset, and the time at this time is used as the starting time of the first duration.

[0051] In an embodiment of the present invention, in order to eliminate the low pressure protection caused by the water tank temperature being close to the ambient temperature or the expansion valve opening being set too small, the working parameters including the water tank temperature and the expansion valve opening are set to adjust the water tank temperature and the expansion valve opening, and the heat pump host is controlled to restart based on the adjusted working parameters.

[0052] In an embodiment of the present invention, after the heat pump host is controlled to restart based on the adjusted working parameters, if the low-pressure switch is disconnected within the first preset time after the heat pump host is restarted, the number of shutdowns and the first time can be updated, and the working parameters are adjusted again based on the number of shutdowns and the first time, and the heat pump host is controlled to restart based on the adjusted working parameters; if the low-pressure switch remains closed, the previous low-pressure protection was due to inappropriate setting of the water tank temperature or the expansion valve opening. At this time, the heat pump host jumps out of the low-pressure protection and resumes normal operation.

[0053] Step 120: If the adjusted operating parameter reaches the parameter threshold and the low-pressure switch is disconnected, it is determined that the heat pump host fails.

[0054] In an embodiment of the present invention, if the adjusted working parameters reach the parameter threshold, that is, the water tank temperature reaches the temperature and the expansion valve opening reaches the opening threshold, the low-pressure switch is still disconnected, that is, the heat pump host is still shut down, then it indicates that the adjustment of the water tank temperature and the expansion valve opening is not sufficient to cause the heat pump host to jump out of the low-pressure protection. At this time, it can be determined that the heat pump host has a fault, and the reason for triggering the low-pressure protection is refrigerant leakage or low ambient temperature; at the same time, in order to protect the water heater, the fault protection of the water heater is triggered, and the water heater is locked to stop the water heater from running.

[0055] In one embodiment, after the heat pump host is restarted based on the adjusted working parameters, if the low-pressure switch remains closed, it is determined that the heat pump host is operating normally, and the number of shutdowns and the first duration are cleared.

[0056] In one embodiment, the adjustment direction of the working parameters is different for different shutdown times and first durations. Specifically, Figure 2 FIG. 1 is a flow chart of adjusting working parameters in a water heater control method according to an embodiment of the present invention. Figure 2 As shown, in the above step 110, adjusting the working parameters based on the number of shutdowns and the first duration may include:

[0057] Step 210: If the number of shutdowns is less than the preset number, and the first duration is less than the second preset duration, the opening of the expansion valve is adjusted to increase the opening of the expansion valve.

[0058] In an embodiment of the present invention, if the number of shutdowns is less than the preset number, and the first time length is less than the second preset time length, the expansion valve opening can be adjusted first to determine whether the current expansion valve opening is too small, resulting in less refrigerant entering the fin heat exchanger to reabsorb heat, causing the absorbed heat to be too low, resulting in the triggering of low pressure protection.

[0059] In the embodiment of the present invention, the opening of the expansion valve is increased by an adjustment value based on the current value to complete an adjustment of the opening of the expansion valve.

[0060] In one embodiment, the adjustment value for adjusting the expansion valve opening each time may be the same, that is, no matter what the current value of the expansion valve opening is, the expansion valve opening is increased by a fixed value.

[0061] In one embodiment, the adjustment value may be determined according to the current value of the expansion valve opening. Specifically, the adjustment value may be in a certain relationship or ratio with the current value of the expansion valve opening, and the adjustment value corresponding to the current value of the expansion valve opening may be determined according to the relationship or ratio, and the adjustment may be performed. For example, the adjustment value of the expansion valve may be set to be inversely proportional to the current value, that is, the smaller the current value, the larger the adjustment value, so that the expansion valve opening can be quickly increased when the expansion valve opening is small.

[0062] Step 220: If the adjusted expansion valve opening reaches the opening threshold, based on the relationship between the water tank temperature and the temperature threshold, the auxiliary heat source is controlled to adjust the water tank temperature and adjust the expansion valve opening to the initial opening.

[0063] In the embodiment of the present invention, if the adjusted expansion valve opening reaches the opening threshold, it indicates that only adjusting the expansion valve opening at this time cannot make the heat pump host jump out of the low-pressure protection, so the water tank temperature can be further adjusted, and the temperature difference between the water tank temperature and the ambient temperature can be increased to make the heat pump host jump out of the low-pressure protection; at the same time, since the water tank temperature has changed, the temperature difference between the water tank temperature and the ambient temperature has changed accordingly, and the working environment of the heat pump host has been adjusted accordingly. At this time, it is necessary to use the adjusted water tank temperature as a new reference to perform a new round of expansion valve opening adjustment, and the expansion valve opening is also recharged, that is, the expansion valve opening is adjusted to the initial opening.

[0064] In the embodiment of the present invention, the water tank temperature is adjusted based on the magnitude relationship between the water tank temperature and the temperature threshold. Specifically, if the water tank temperature is less than the temperature threshold, the water tank temperature is increased by a preset temperature value based on the current temperature value; if the water tank temperature reaches the temperature threshold, it indicates that the adjustment of the water tank temperature at this time cannot cause the heat pump host to jump out of the low-voltage protection, so the water tank temperature is no longer adjusted.

[0065] In the embodiment of the present invention, since the water tank temperature is adjusted, and the heat pump main unit in the water heater is shut down and cannot be used, the auxiliary heat source is controlled to work to heat the water in the water tank to adjust the water tank temperature; after the water tank temperature is adjusted, the auxiliary heat source is controlled to be turned off. The auxiliary heat source can be a heat source such as an electric heating system, which can be adjusted according to the design of the water heater and is not specifically limited here.

[0066] In one embodiment, the above steps 210 to 220 are for the case where the number of shutdowns is less than the preset number and the first duration is less than the second preset duration. If the number of shutdowns is greater than the preset number and the first duration is less than the second preset duration, the water tank temperature is adjusted based on the magnitude relationship between the water tank temperature and the temperature threshold. The method for adjusting the water tank temperature can refer to the relevant method in the above step 220, which will not be repeated here.

[0067] In one embodiment, in the above-mentioned process of adjusting the expansion valve opening and the water tank temperature, the first time length is used to limit the adjustment of the working parameters to avoid adjusting the working parameters only by the downtime length. In the event of a failure of the heat pump host, the heat pump host will be restarted multiple times, thereby protecting the water heater.

[0068] In one embodiment, the adjustment direction of the working parameters is different, and the control method of the water heater, specifically, the heat pump host is also different. Specifically, Figure 3 1 is a flow chart of controlling the restart of the heat pump host when the adjusted working parameter in a water heater control method according to an embodiment of the present invention is the expansion valve opening and the adjusted expansion valve opening does not reach the opening threshold, such as Figure 3 As shown, when the number of shutdowns is less than the preset number of times and the first duration is less than the second preset duration, the expansion valve opening is adjusted, and the adjusted expansion valve opening does not reach the opening threshold at this time, then in the above step 110, based on the adjusted working parameters, controlling the heat pump host to restart may include:

[0069] Step 310: Restart the heat pump host.

[0070] In the embodiment of the present invention, after determining the adjusted expansion valve opening, the heat pump host is restarted. Optionally, only the heat pump host may be restarted without restarting components in the water heater that are not associated with the heat pump host, such as an auxiliary heat source.

[0071] Step 320: Based on the adjusted expansion valve opening, control the operation of the heat pump host.

[0072] In the embodiment of the present invention, since only the opening of the expansion valve is adjusted but the water tank temperature is not adjusted, there is no need to enable the auxiliary heat source to heat the water in the water tank to keep the water tank temperature unchanged; at the same time, the expansion valve is reset after the heat pump host is restarted, so the opening of the expansion valve is adjusted to the adjusted expansion valve opening, and based on this opening, the operation of the heat pump host in the water heater is controlled.

[0073] In one embodiment, after the heat pump host is controlled to work based on the adjusted expansion valve opening, if the low-pressure switch is disconnected within the first preset time after the heat pump host is restarted, it indicates that the heat pump host is shut down again at this time, so the number of shutdowns is cumulatively updated, and the first time is updated based on the disconnection time of the low-pressure switch. The disconnection time of the low-pressure switch is used as the shutdown time of the most recent shutdown, that is, the end time of the first time, and the first time is obtained and updated by subtracting the start time of the first time from the shutdown time.

[0074] In one embodiment, after the above step 320, if the low-pressure switch is disconnected, the adjustment direction of the working parameters can be determined according to the number of shutdowns and the first duration. For details, please refer to the above steps 210, 220 and related steps, which will not be repeated here. Repeat the above steps until the heat pump host jumps out of the low-pressure protection and can work normally, or until the working parameters reach the parameter threshold, turn on the fault protection of the heat pump host, and lock the water heater. Therefore, through the above steps, it is ensured that the heat pump host can work normally when there is no fault, and it is ensured that the heat pump host can be timely protected when there is a fault, thereby improving the stability and reliability of the water heater.

[0075] In one embodiment, Figure 4 FIG. 1 is a flow chart of controlling the restart of the heat pump host when the adjusted working parameter is the water tank temperature in a water heater control method according to an embodiment of the present invention, such as Figure 4 As shown, when the number of shutdowns is greater than the preset number of times and the first duration is less than the second preset duration, the adjusted expansion valve opening reaches the opening threshold, and the water tank temperature is adjusted. In the above step 110, based on the adjusted working parameters, controlling the heat pump host to restart may include:

[0076] Step 410: Restart the heat pump host.

[0077] In the embodiment of the present invention, after adjusting the temperature of the water tank, the heat pump host is restarted. Optionally, only the heat pump host may be restarted without restarting components in the water heater that are not associated with the heat pump host, such as an auxiliary heat source.

[0078] Step 420: Based on the initial opening and the adjusted water tank temperature, control the operation of the heat pump host.

[0079] In the embodiment of the present invention, since the water tank temperature changes, the temperature difference between the water tank temperature and the ambient temperature changes accordingly, and the working environment of the heat pump host is adjusted accordingly. The adjusted water tank temperature is used as a new reference to adjust the expansion valve opening in a new round, so that the heat pump host jumps out of the low-pressure protection. If the expansion valve opening has been adjusted before, the expansion valve opening is also reset. After the heat pump host is restarted and the expansion valve is reset, the expansion valve opening is adjusted to the initial opening, that is, the expansion valve opening before adjustment, and the heat pump host is controlled to work according to this opening.

[0080] In one embodiment, Figure 5 FIG. 1 is a flow chart of controlling the restart of the heat pump host when the adjusted working parameters in a water heater control method according to an embodiment of the present invention are the expansion valve opening and the water tank temperature. Figure 5 As shown, when the adjusted expansion valve opening reaches the opening threshold, the expansion valve opening and the water tank temperature are adjusted. Then, in the above step 110, based on the adjusted working parameters, controlling the heat pump host to restart may include:

[0081] Step 510: Restart the heat pump host.

[0082] In the embodiment of the present invention, after adjusting the temperature of the water tank, the heat pump host is restarted. Optionally, only the heat pump host may be restarted without restarting components in the water heater that are not associated with the heat pump host, such as an auxiliary heat source.

[0083] Step 520: Based on the adjusted water tank temperature, control the operation of the heat pump host.

[0084] In the embodiment of the present invention, when the expansion valve opening reaches the opening threshold, the heat pump host still does not jump out of the low-pressure protection, indicating that the current water tank temperature is not a suitable temperature for the heat pump host to work normally. Therefore, the operation of the heat pump host is controlled based on the adjusted water tank temperature and the initial opening of the expansion valve, so that the adjusted water tank temperature is used as a new benchmark, and a new round of expansion valve opening adjustment is performed to make the heat pump host jump out of the low-pressure protection.

[0085] In one embodiment, since a new round of expansion valve opening adjustment is performed with the adjusted water tank temperature as a new reference, the number of shutdowns and the first duration are first reset to zero to prevent the number of shutdowns and the first duration based on the water tank temperature before adjustment from affecting the adjustment of the current expansion valve opening; then determine whether the low-pressure switch is closed within the first preset time after the heat pump host is restarted. After resetting the number of shutdowns and the first duration, if the low-pressure switch is disconnected within the first preset time after the heat pump host is restarted, it indicates that the heat pump host is shut down at this time, and the number of shutdowns is updated, that is, the number of shutdowns is recorded as 1; at the same time, the disconnection time of the low-pressure switch is used as the starting time of the first duration, and when the low-pressure switch is disconnected again and the heat pump host is shut down again, the first duration is calculated based on the starting time.

[0086] In one embodiment, after the above steps 420 and 520, if the low-pressure switch is disconnected within the first preset time after the heat pump host is restarted, the adjustment direction of the working parameters can be determined according to the number of shutdowns and the first time. For details, please refer to the above steps 210, 220 and related steps, which will not be repeated here. Repeat the above steps until the heat pump host jumps out of the low-pressure protection and can work normally, or until the working parameters reach the parameter threshold, turn on the fault protection of the heat pump host, and lock the water heater. Therefore, through the above steps, it is ensured that the heat pump host can work normally when there is no fault, and it is ensured that the heat pump host can be timely protected when there is a fault, thereby improving the stability and reliability of the water heater.

[0087] In a specific embodiment, Figure 6 is a flow chart of a specific implementation of a water heater control method according to an embodiment of the present invention. Figure 6 Taking the water heater control method of the present invention as an example, the water heater control method of the present invention is further explained.

[0088] like Figure 5 As shown, the water heater is turned on, and the expansion valve is reset and adjusted to the opening P n If the water heater is turned on for the first time, that is, the heat pump host has not been restarted before, then n = 0, that is, the expansion valve is adjusted to the initial opening P0. After the water heater is started for a period of time t1, or in other words, after the water heater works stably, it starts to detect whether the low-pressure switch is closed to determine whether the heat pump host is shut down.

[0089] If the low-pressure switch is closed, it indicates that the heat pump host is operating normally, and the shutdown number n and the recorded shutdown time T n Cleared.

[0090] If the low-pressure switch is disconnected, it means that the heat pump host is shut down. At this time, the number of shutdowns n is accumulated once, and the current shutdown time T is recorded. nAt this time, it is further determined whether the number of shutdowns n is greater than the preset number N, and the first duration T n -Whether T1 is less than the preset time t2.

[0091] If the number of shutdowns n is greater than the preset number N, and the first duration T n - If T1 is less than the preset time t2, it is further determined whether the water tank temperature Tt is greater than the temperature threshold Ts.

[0092] If the number of shutdowns n is less than the preset number N, and the first duration T n -T1 is less than the preset time t2, then the preset value is increased based on the current expansion valve opening, that is, P n =Pn-1+m, and get the opening degree P of the expansion valve that needs to be adjusted after the next heat pump host restarts n At this time, further determine the expansion valve opening P n Whether it is the maximum opening.

[0093] If the expansion valve opening P n If it is not the maximum opening, the heat pump host is restarted to execute the control method again, so that the heat pump host jumps out of the low-pressure protection, or it is determined that the heat pump host fails and the fault protection of the water heater is turned on.

[0094] If the expansion valve opening P n is the maximum opening, then further determine the water tank temperature T t Is it greater than the temperature threshold Ts?

[0095] For expansion valve opening P n is the maximum opening, that is, at the current water tank temperature T t The heat pump host cannot be caused to jump out of the low-voltage protection under the condition that the shutdown number n is greater than the preset number N, and the first duration T n -T1 is less than the preset time t2, if the water tank temperature T t Greater than the temperature threshold T s , it indicates that the working parameters have been adjusted to the corresponding parameter thresholds, and the heat pump host cannot jump out of the low-voltage protection. At this time, it can be determined that the heat pump host has a fault, so the water heater is locked to protect the water heater from faults.

[0096] If the water tank temperature T t Less than the temperature threshold T s , then other auxiliary heat sources are used to increase the water tank temperature T t Increase the preset temperature T h , and n and T n Reset to zero to adjust the water tank temperature T tOn this basis, the control method is executed again to start a new round of adjustment of the working parameters, so that the heat pump host jumps out of the low-voltage protection, or it is determined that the heat pump host fails and the fault protection of the water heater is turned on.

[0097] The water heater control method provided by the embodiment of the present invention takes the time when the low-pressure switch is triggered to disconnect for the first time after being closed for the first preset time during the current heating process of the heat pump water heater as the starting time of the first time, and starts recording the first time when the low-pressure protection is triggered after the heat pump host is operating normally or resuming normal operation, thereby adjusting the expansion valve opening and the water tank temperature according to the number of shutdowns and the first time, so that the heat pump host jumps out of the low-pressure protection; takes the time when the low-pressure switch is triggered to disconnect for the first time within the first preset time when the heat pump host is started during the current heating process of the heat pump water heater at the current water tank temperature, as the starting time of the first time, and starts recording the first time when the heat pump host is directly triggered to stop after the heat pump water heater is turned on, thereby The expansion valve opening and the water tank temperature are adjusted, and the recording of the first time length is restarted when the water tank temperature is adjusted to the current water tank temperature, thereby starting a new round of adjustment of the expansion valve opening and the water tank temperature, so that the heat pump host can jump out of the low-pressure protection; thereby avoiding the low-pressure protection of the heat pump host being triggered due to the water tank temperature being too low or the expansion valve opening being too small, so that the water heater can work normally at a lower ambient temperature, thereby improving the working stability and reliability of the water heater; at the same time, when the expansion valve opening and the water tank temperature reach the corresponding parameter thresholds, the low-pressure switch is still disconnected, then the influence of the water tank temperature being too low or the expansion valve opening being too small on the low-pressure switch can be eliminated, thereby determining that the heat pump host has a fault and locking the water heater, thereby realizing fault protection for the water heater, and further improving the reliability of the water heater.

[0098] According to an embodiment of the present invention, on the other hand, a heat pump water heater is provided, comprising a controller, wherein the controller is used to execute any of the heat pump water heater control methods described above.

[0099] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The specific contents of the above specific embodiments only express several embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A control method for a heat pump water heater, wherein the heat pump water heater comprises a heat pump host, characterized in that: The method comprises: If the low-pressure switch of the heat pump host is disconnected, the compressor is controlled to stop, the number of shutdowns and the first duration of the compressor are recorded, and based on the number of shutdowns and the first duration, the working parameters are adjusted, and based on the adjusted working parameters, the heat pump host is controlled to restart; the working parameters include the water tank temperature and the expansion valve opening; the starting time of the first duration is the time when the low-pressure switch is triggered to disconnect for the first time after the low-pressure switch remains closed for the first preset time during the current heating process of the heat pump water heater, or the time when the low-pressure switch is triggered to disconnect for the first time within the first preset time when the heat pump host is started at the current water tank temperature; the end time of the first duration is the time when the low-pressure switch is most recently triggered to disconnect; If the adjusted working parameter reaches the parameter threshold, the low-pressure switch is disconnected, and it is determined that the heat pump host fails.

2. The method according to claim 1, characterized in that The heat pump water heater further includes an auxiliary heat source, which is used to heat the water tank. The adjusting of the working parameters based on the number of shutdowns and the first duration includes: If the shutdown number is less than the preset number, and the first duration is less than the second preset duration, adjusting the opening of the expansion valve to increase the opening of the expansion valve; If the adjusted expansion valve opening reaches the opening threshold, based on the relationship between the water tank temperature and the temperature threshold, the auxiliary heat source is controlled to adjust the water tank temperature and adjust the expansion valve opening to the initial opening.

3. The method according to claim 1, characterized in that The heat pump water heater further includes an auxiliary heat source, which is used to heat the water tank. The adjusting the working parameters based on the number of shutdowns and the first duration includes: If the number of shutdowns is greater than the preset number and the first duration is less than the second preset duration, based on the relationship between the water tank temperature and the temperature threshold, the auxiliary heat source is controlled to operate to adjust the water tank temperature.

4. The method according to claim 2, characterized in that: If the adjusted expansion valve opening does not reach the opening threshold, then based on the adjusted working parameters, controlling the heat pump host to restart includes: Restarting the heat pump host; Based on the adjusted expansion valve opening, the operation of the heat pump host is controlled.

5. The method according to claim 1, characterized in that After controlling the heat pump host to restart based on the adjusted working parameters, the method further comprises: If the low-pressure switch is disconnected within the first preset time after the heat pump host is restarted, the number of shutdowns is cumulatively updated, and the first time is updated based on the disconnection time of the low-pressure switch.

6. The method according to claim 2, characterized in that If the adjusted expansion valve opening reaches the opening threshold, then based on the adjusted working parameters, controlling the heat pump host to restart includes: Restarting the heat pump host; Based on the initial opening and the adjusted water tank temperature, the heat pump host is controlled to operate.

7. The method according to claim 3, characterized in that If the number of shutdowns is greater than a preset number and the first duration is less than the preset duration, then based on the adjusted working parameters, controlling the heat pump host to restart includes: Restarting the heat pump host; Based on the adjusted water tank temperature, the heat pump host is controlled to operate.

8. The method according to claim 1, characterized in that If the water tank temperature is adjusted, then after controlling the heat pump host to restart based on the adjusted working parameters, the method further includes: First, the number of shutdown times and the first duration are cleared to zero, and then it is determined whether the low-pressure switch is closed within the first preset time after the heat pump host is restarted.

9. The method according to claim 1, characterized in that: After controlling the heat pump host to restart based on the adjusted working parameters, the method further comprises: If the low-pressure switch remains closed, it is determined that the heat pump host operates normally, and the number of shutdowns and the first duration are cleared.

10. A heat pump water heater, characterized in that: It comprises a controller, and the controller is used to execute the heat pump water heater control method as described in any one of claims 1-9.

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