WO2023005246A1

WO2023005246A1 - Control method for air source heat pump unit

Info

Publication number: WO2023005246A1
Application number: PCT/CN2022/083676
Authority: WO
Inventors: 张宝库; 韩伟涛; 张丽娟; 毛守博; 卢大海
Original assignee: 青岛海尔空调电子有限公司; 青岛海尔空调器有限总公司; 海尔智家股份有限公司
Priority date: 2021-07-30
Filing date: 2022-03-29
Publication date: 2023-02-02
Also published as: CN113623889B; CN113623889A

Abstract

A control method for an air source heat pump unit, aiming at solving the problem that water side heat exchangers of existing air source heat pump units are prone to frost cracking in a using process. For this objective, the water flow in a water circulation loop is compared with preset water flow, such that a refrigerant circulation loop is controlled to operate; an operation working condition of the refrigerant circulation loop and an opening and closing state of an assistive electric heating device are controlled by obtaining an outlet water temperature in the water circulation loop when the air source heat pump unit is in a heating working condition; and the operation states of a compressor and an electronic expansion valve are controlled by obtaining a low pressure of the refrigerant circulation loop when the air source heat pump unit is in a refrigeration working condition, such that the problem that a second heat exchanger is prone to frost cracking due to factors such as too small water flow and too low water temperature is effectively solved under any working condition, thereby ensuring the reliability of the second heat exchanger.

Description

Control method for air source heat pump unit

technical field

The invention relates to the technical field of antifreeze for air source heat pump units, and specifically provides a control method for air source heat pump units.

Background technique

With the ever-increasing demand of users, the development of existing heat exchangers tends to be refined, with small volume and high heat exchange efficiency, so it is widely used in air source heat pump units. However, if the water flow through the existing water-side heat exchanger is insufficient or the water temperature is too low, or the temperature is too low during the cooling process, the water-side heat exchanger will be frozen and cracked. In addition, the outdoor heat exchanger of the existing air source heat pump unit will frost during the heating process. In order to ensure the heating effect of the air source heat pump unit, when the outdoor heat exchanger frosts to a certain extent, the air The source heat pump unit will enter the defrosting condition. Most of the existing air source heat pump units adopt the reverse defrosting method. However, based on this defrosting method, when the air source heat pump unit switches to the defrosting condition, the The refrigerant will cause a large cold and heat impact on the water side heat exchanger, which will easily cause damage to the water side heat exchanger. When the air source heat pump unit is in cooling condition, if the pressure of the low-pressure side in the circuit is too low, when the temperature of the refrigerant entering the water-side heat exchanger is lower than its freezing point, the water-side heat exchanger may appear Frozen cracking phenomenon, which makes it unusable.

Contents of the invention

The present invention aims to solve the above-mentioned technical problem, that is, to solve the problem that the water-side heat exchanger of the existing air source heat pump unit is easy to be frozen and cracked during operation.

The present invention provides a control method for an air source heat pump unit. The air source heat pump unit includes a refrigerant circulation loop, a water circulation loop and an auxiliary electric heating device. The refrigerant circulation loop is provided with a compressor, a four-way valve, a second A heat exchanger, an electronic expansion valve and a second heat exchanger, the water circulation circuit is provided with a circulating water pump, the refrigerant circulation circuit and the water circulation circuit can realize heat exchange through the second heat exchanger, the The auxiliary electric heating device can heat the water in the water circulation loop, and the control method includes: when the air source heat pump unit starts to start, first controlling the start of the circulating water pump; obtaining the water flow rate in the water circulation loop ; If the water flow rate is greater than or equal to the preset water flow rate, then control the operation of the refrigerant circulation loop; when the air source heat pump unit is in the heating mode, obtain the outlet water temperature of the water circulation loop; according to the outlet water Temperature, to control the operating conditions of the refrigerant circulation loop and the opening and closing state of the auxiliary electric heating device; when the air source heat pump unit is in the cooling condition, obtain the low pressure of the refrigerant circulation loop; according to the The numerical range of the low pressure controls the operation state of the compressor and the operation state of the electronic expansion valve.

In the preferred technical solution of the above control method, the step of "obtaining the outlet water temperature of the water circulation loop" specifically includes: acquiring the initial outlet water temperature of the water circulation loop when the water circulation loop is started; after a preset running time, Obtain the current outlet water temperature of the water circulation circuit; the step of "controlling the operating conditions of the refrigerant circulation circuit and the opening and closing state of the auxiliary electric heating device according to the outlet water temperature" specifically includes: according to the initial outlet water temperature and the current outlet water temperature to control the operating conditions of the refrigerant circulation loop and the on-off state of the auxiliary electric heating device.

In the preferred technical solution of the above control method, the step of "controlling the operating condition of the refrigerant circulation loop and the opening and closing state of the auxiliary electric heating device according to the initial outlet water temperature and the current outlet water temperature" specifically includes : if the difference between the current outlet water temperature and the initial outlet water temperature is less than or equal to the preset outlet water temperature difference and the current outlet water temperature is less than or equal to the first preset outlet water temperature, then control the operating condition of the refrigerant circulation loop No change and the auxiliary electric heating device is turned on.

In the preferred technical solution of the above control method, the control method further includes: re-obtaining the outlet water temperature of the water circulation loop when the auxiliary electric heating device is turned on; when the re-acquired outlet water temperature is greater than the second When the outlet water temperature is preset, the auxiliary electric heating device is turned off; wherein, the second preset outlet water temperature is greater than the first preset outlet water temperature.

In the preferred technical solution of the above control method, the refrigerant circulation circuit is also provided with a high and low pressure balance valve, and the control method further includes: when the air source heat pump unit starts to operate in the defrosting mode, controlling the The four-way valve changes direction and controls the opening of the high and low pressure balance valves.

In the preferred technical solution of the above control method, the step of "controlling the opening of the high and low pressure balance valve" specifically includes: controlling the opening of the preset protection period of the high and low pressure pressure balance valve.

In the preferred technical solution of the above control method, the step of "controlling the operating state of the compressor and the operating state of the electronic expansion valve according to the numerical range of the low pressure" includes: if the low pressure is less than If the first preset low pressure is greater than or equal to the second preset low pressure and lasts for a first preset time period, then the operating frequency of the compressor and the opening degree of the electronic expansion valve are controlled to remain unchanged.

In the preferred technical solution of the above control method, the step of "controlling the operating state of the compressor and the operating state of the electronic expansion valve according to the numerical range of the low pressure" further includes: if the low pressure If it is less than the second preset low pressure and greater than or equal to the third preset low pressure for a second preset duration, then the operating frequency of the compressor is controlled not to increase and the opening of the electronic expansion valve is controlled to increase. big.

In the preferred technical solution of the above control method, the step of "controlling the operating state of the compressor and the operating state of the electronic expansion valve according to the numerical range of the low pressure" further includes: if the low pressure If the pressure is less than the third preset low pressure and greater than or equal to the fourth preset low pressure for a third preset time period, the operating frequency of the compressor is controlled to decrease and the opening of the electronic expansion valve is controlled to increase.

In the preferred technical solution of the above control method, the step of "controlling the operating state of the compressor and the operating state of the electronic expansion valve according to the numerical range of the low pressure" further includes: if the low pressure If the pressure is less than the fourth preset low pressure and lasts for a fourth preset time period, the compressor and the electronic expansion valve are controlled to be closed.

In the case of adopting the above technical solution, the present invention can compare the water flow in the water circulation circuit with the preset water flow, and if the water flow is greater than or equal to the preset water flow, control the refrigerant The operation of the circulation loop can also control the operating condition of the refrigerant circulation loop and the opening and closing state of the auxiliary electric heating device by obtaining the temperature of the outlet water in the water circulation loop when the air source heat pump unit is in the heating condition Controlling the operating state of the compressor and the operating state of the electronic expansion valve by obtaining the low pressure of the refrigerant circulation circuit when the air source heat pump unit is in the cooling condition, therefore, the control method can effectively ensure Under any working conditions, the second heat exchanger will not be affected by factors such as too little water flow, too low water temperature, etc., causing it to be frozen and cracked, so as to effectively ensure its reliability.

Description of drawings

Describe preferred embodiment of the present invention below in conjunction with accompanying drawing, in the accompanying drawing:

Fig. 1 is the structural representation of air source heat pump unit of the present invention;

Fig. 2 is the flow chart of main steps of the control method of the present invention;

Fig. 3 is the flow chart of specific steps of the first preferred embodiment of the control method of the present invention;

Fig. 4 is the flow chart of specific steps of the second preferred embodiment of the control method of the present invention;

Reference signs:

1. Compressor; 2. Four-way valve; 3. First heat exchanger; 4. Electronic expansion valve; 5. Second heat exchanger; 6. Gas-liquid separator; 7. Low pressure sensor; 8. Circulating water pump ; 9. Flow meter; 10. Outlet water temperature sensor; 11. High and low pressure pressure balance valve.

Detailed ways

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present invention, and are not intended to limit the protection scope of the present invention. Those skilled in the art can make adjustments as needed so as to adapt to specific applications. For example, the air source heat pump unit described in the present invention may be a split air source heat pump unit or an integral air source heat pump unit, which is not restrictive, and technicians can set the present invention according to the actual use requirements. The object to which the control method is applied. Such changes related to application objects do not deviate from the basic principle of the present invention, and belong to the protection scope of the present invention.

It should be noted that, in the description of this preferred embodiment, unless otherwise clearly stipulated and limited, the term "connection" should be understood in a broad sense, for example, it can be directly connected, or indirectly connected through an intermediary, or it can be Communication within two elements should therefore not be construed as a limitation of the invention. Those skilled in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In addition, it should also be noted that in the description of the present invention, although the application describes the steps of the control method of the present invention in a specific order, these orders are not limiting, without departing from the basic principles of the present invention Under the premise, those skilled in the art may perform the steps in a different order.

Specifically, first refer to FIG. 1 , which is a schematic structural diagram of the air source heat pump unit of the present invention. As shown in Figure 1, the air source heat pump unit of the present invention includes a refrigerant circulation loop, a water circulation loop and an auxiliary electric heating device (not shown in the figure), the refrigerant circulation loop is provided with a compressor 1, a four-way valve 2, The first heat exchanger 3, the electronic expansion valve 4, the second heat exchanger 5 and the gas-liquid separator 6, the low-pressure pressure sensor 7 are arranged at the air inlet of the compressor 1, of course, the specific setting position is not limited; the water circulation A circulating water pump 8 and a flow meter 9 are arranged on the circuit, and the circulating water pump 8 and the flow meter 9 are arranged on the water inlet side of the second heat exchanger 5, and the outlet water temperature sensor 10 is arranged on the outlet water side of the second heat exchanger 5, so as to detect The temperature of the water in the water circulation loop after passing through the second heat exchanger 5; it should be noted that although the water circulation loop shown in the figure is open, this is only schematic, and the water circulation The circuit can also be provided with a water inlet and a water intake to exchange chilled water with the outside world. The refrigerant circulation loop and the water circulation loop can exchange heat through the second heat exchanger 5, and the auxiliary electric heating device can heat the water in the water circulation loop.

It should be noted that the present invention does not impose any restrictions on the specific types of the first heat exchanger 3, the second heat exchanger 5, the low pressure sensor 7 and the outlet water temperature sensor 10. The first heat exchanger 3 and the second heat exchanger 5 can be a plate heat exchanger or a casing heat exchanger, and the low-pressure pressure sensor 7 can be a capacitive pressure sensor, a piezoresistive pressure sensor, a piezoelectric pressure sensor, or an outlet water temperature sensor 10 can be a thermal sensor or a thermocouple sensor, and technicians can set it by themselves according to actual conditions.

In addition, the air source heat pump unit of the present invention is provided with heating working conditions, cooling working conditions and defrosting working conditions. Specifically, when the air source heat pump unit is in the heating working condition, the first heat exchanger 3 is used as evaporator, and the second heat exchanger 5 is used as a condenser; when the air source heat pump unit is in cooling and defrosting conditions, the first heat exchanger 3 is used as a condenser, and the second heat exchanger 5 is used as an evaporator. Of course, it should be noted that the present invention does not impose any restrictions on the types of specific working conditions set for the air source heat pump unit. Obviously, other working conditions can also be set, and technicians can set them according to the actual situation.

Further, the air source heat pump unit of the present invention also includes a controller, which can execute the control method of the present invention, for example: the controller can control the operating conditions of the refrigerant circulation loop, control the auxiliary electric The opening and closing state of the heating device controls the operating state of the compressor 1, the electronic expansion valve 4 and the circulating water pump 8, etc. Those skilled in the art can understand that the present invention does not impose any restrictions on the specific structure and model of the controller, and the controller can be either the original controller of the air source heat pump unit or a The control method of the present invention is provided with a separate controller, and technicians can set the structure and model of the controller by themselves according to actual use requirements.

Referring next to FIG. 2 , FIG. 2 is a flow chart of the main steps of the control method of the present invention. As shown in Figure 2, based on the air source heat pump unit described in the above embodiments, the control method of the present invention includes the following steps:

S1: When the air source heat pump unit starts to start, the circulating water pump is first controlled to start;

S2: obtaining the water flow rate in the water circulation circuit;

S3: If the water flow rate is greater than or equal to the preset water flow rate, control the operation of the refrigerant circulation loop;

S4: When the air source heat pump unit is in the heating condition, obtain the outlet water temperature of the water circulation circuit;

S5: According to the outlet water temperature, control the operating condition of the refrigerant circulation circuit and the opening and closing state of the auxiliary electric heating device;

S6: When the air source heat pump unit is in the cooling condition, obtain the low-pressure pressure of the refrigerant circulation circuit;

S7: Control the running state of the compressor and the running state of the electronic expansion valve according to the value range of the low pressure.

In steps S1 to S3, when the air source heat pump unit starts, the controller first controls the circulating water pump 8 to start, and then obtains the water flow in the water circulation loop, if the water flow is greater than or equal to the preset water flow , the controller controls the operation of the refrigerant circulation loop. It should be noted that the present invention does not impose any restrictions on the specific value of the preset water flow rate, and technicians can set it according to actual use requirements; preferably, the preset water flow rate is 70% of the standard water flow rate, The standard water flow rate is the water flow rate when the unit is in stable operation.

In addition, it should be noted that the acquisition method of the water flow rate can be monitored by the water flow rate, or by the water inflow time. The present invention does not make any limitation on the acquisition method of the water flow rate. The actual situation is set by itself. As a preferred setting method, the present invention monitors the flow rate of water through the flowmeter 9, and then obtains the water flow rate in the water circulation loop, and determines the water flow rate through the water flow rate to ensure that Accuracy of the water flow obtained.

In steps S4 and S5, when the air source heat pump unit is in heating mode, the outlet water temperature of the water circulation circuit is obtained, and the outlet water temperature sensor 10 can convert the outlet water temperature into an output signal and transmit it to the controller ; Next, the controller controls the operating conditions of the refrigerant circulation circuit and the on-off state of the auxiliary electric heating device according to the received outlet water temperature. It should be noted that the present invention does not impose any restrictions on the above-mentioned specific control methods, and technicians can set them by themselves according to actual use requirements, as long as the operating conditions of the refrigerant circulation loop and the auxiliary electric heating device are controlled according to the outlet water temperature The opening and closing state of the outlet water temperature belongs to the protection scope of the present invention; and the present invention does not impose any restrictions on the specific acquisition method and acquisition position of the outlet water temperature, and technicians can set it according to the actual situation.

In steps S6 and S7, when the air source heat pump unit is in the cooling condition, the low pressure in the refrigerant circulation circuit is obtained, and the low pressure sensor 7 can convert the low pressure into an output signal and transmit it to the controller Next, the controller controls the operating state of the compressor 1 and the operating state of the electronic expansion valve 4 according to the value range of the low pressure. It should be noted that the present invention does not impose any restrictions on the specific value range of the numerical range, which can be set through multiple tests, or can be set according to the actual operating conditions of the air source heat pump unit, and technicians can Set it yourself according to the actual situation.

first preferred embodiment

Referring to Fig. 3, Fig. 3 is a flow chart of specific steps of the first preferred embodiment of the control method of the present invention. As shown in Figure 3, based on the air source heat pump unit described in the above embodiments, the control method of the first preferred embodiment of the present invention includes the following steps:

S101: When the air source heat pump unit starts to start, first control the circulating water pump to start;

S102: Obtain the water flow rate in the water circulation loop;

S103: If the water flow rate is greater than or equal to the preset water flow rate, control the operation of the refrigerant circulation loop;

S104: When the air source heat pump unit is in the heating condition, when the water circulation loop starts, obtain the initial outlet water temperature of the water circulation loop;

S105: Obtain the current outlet water temperature of the water circulation circuit after a preset running time;

S106: If the difference between the current outlet water temperature and the initial outlet water temperature is less than or equal to the preset outlet water temperature difference and the current outlet water temperature is less than or equal to the first preset outlet water temperature, control the operating condition of the refrigerant circulation loop to remain unchanged and turn on the auxiliary electric heating device;

S107: Obtain the outlet water temperature of the water circulation circuit again when the auxiliary electric heating device is turned on;

S108: When the outlet water temperature obtained again is greater than the second preset outlet water temperature, turn off the auxiliary electric heating device;

S109: When the air source heat pump unit starts to operate in the defrosting condition, control the reversing of the four-way valve and control the high and low pressure balance valve to open the preset protection time.

In steps S101 to S103, when the air source heat pump unit starts to start, the controller first controls the circulating water pump 8 to start, preferably after the circulating water pump 8 runs for a preset operation time, then obtains the water flow in the water circulation loop, In order to effectively ensure that the second heat exchanger 5 is filled with enough water, thereby effectively avoiding the phenomenon of "emptying" in the second heat exchanger 5, specifically, if the water flow rate is greater than or equal to the preset water flow rate, then the The controller controls the operation of the refrigerant circulation loop. If the water flow rate is less than the preset water flow rate, the controller controls the circulating water pump 8 to continue to run and controls the refrigerant circulation loop not to run until the water flow rate is greater than Or equal to the preset water flow. In this preferred embodiment, the preset running time is 2 to 3 minutes, and the preset water flow rate is 70% of the standard water flow rate. It should be noted that the acquisition method of the water flow rate can be monitored by the water flow rate, and can also be monitored by the water inflow time. The present invention does not make any limitation on the acquisition method of the water flow rate, and technicians can Self-setting, as a preferred setting method, the present invention monitors the flow rate of water through the flow meter 9, and then obtains the water flow rate in the water circulation circuit, and determines the water flow rate through the water flow rate to ensure that the obtained The accuracy of the water flow rate. It should also be noted that the setting of the standard water flow rate can be the default setting of the air source heat pump unit when it leaves the factory, or it can be set by the user according to the actual operating conditions, and the present invention does not make any restrictions on this , technicians can set it by themselves.

In steps S104 and S105, when the air source heat pump unit is in heating mode, when the water circulation loop is started, the initial outlet water temperature of the water circulation loop is obtained, and after a preset running time, the The current outlet water temperature of the water circulation circuit, the outlet water temperature sensor 10 can convert the initial outlet water temperature and the current outlet water temperature into an output signal and transmit it to the controller, and then the controller, according to the received initial outlet water temperature and the current outlet water temperature signal to control the operating conditions of the refrigerant circulation loop and the on-off state of the auxiliary electric heating device. In this preferred embodiment, according to the results of multiple tests, the preset running time is set to 30 minutes. Of course, this is only a preferred setting value and is not limiting. The actual operating status of the heat pump unit is set by itself. It should be noted that, the present invention does not impose any limitation on the way of obtaining the initial outlet water temperature and the current outlet water temperature, and technicians can set them according to the actual situation.

In step S106, if the difference between the current outlet water temperature and the initial outlet water temperature is less than or equal to the preset outlet water temperature difference and the current outlet water temperature is less than or equal to the first preset outlet water temperature, control the refrigerant circulation loop The operating conditions of the electric heater remain unchanged and the auxiliary electric heating device is turned on.

In steps S107 and S108, when the auxiliary electric heating device is turned on, the outlet water temperature of the water circulation circuit is obtained again, and when the obtained outlet water temperature is greater than the second preset outlet water temperature, the auxiliary electric heating device is turned off. Electric heating device.

In this embodiment, the preset water temperature difference is preferably 5°C, the second preset water temperature is greater than the first preset water temperature, wherein the first preset water temperature is preferably 20°C, The second preset outlet water temperature is preferably 22°C. Of course, the present invention does not impose any restrictions on the specific values of the preset outlet water temperature difference, the first preset outlet water temperature, and the second preset outlet water temperature. It can be obtained through multiple experiments, and can also be obtained through user's own setting, which is not restrictive, and technicians can set by themselves according to the actual situation.

Preferably, the air source heat pump unit also includes a high and low pressure balancing branch, one end of the high and low pressure balancing branch is connected between the exhaust port of the compressor 1 and the four-way valve 2, and the other end is connected to the compressor 1 Between the gas inlet and the gas-liquid separator 6, a high and low pressure balance valve 11 is arranged on the high and low pressure balance branch. In step S109, when the air source heat pump unit starts to operate under the defrosting condition, the four-way valve 2 is controlled to change direction and the high and low pressure balance valve 11 is controlled to open for a preset protection period. Therefore, the second heat exchanger 5 The passing refrigerant and water will not cause a large alternation of cold and heat due to the switching of the working conditions of the air source heat pump unit, and the setting of the high and low pressure balance valve 11 can effectively ensure that the second heat exchanger 5 will not be cracked by freezing situation, thereby ensuring its service life. In this preferred embodiment, after multiple tests, the preset protection time is 30 seconds. Of course, this is only a preferred setting value, and it is not restrictive. A specific duration of the preset protection duration is set.

In addition, it should be noted that the present invention does not impose any restrictions on the specific timing of the air source heat pump unit entering the defrosting mode, and technicians can set it according to actual use requirements.

Second preferred embodiment

Referring to Fig. 4, Fig. 4 is a flow chart of specific steps of the second preferred embodiment of the control method of the present invention. As shown in Figure 4, based on the air source heat pump unit described in the above embodiments, the control method in the second preferred embodiment of the present invention includes the following steps:

S201: When the air source heat pump unit starts to start, first control the circulating water pump to start;

S202: Obtain the water flow rate in the water circulation loop;

S203: If the water flow rate is greater than or equal to the preset water flow rate, control the operation of the refrigerant circulation loop;

S204: Obtain the low-pressure pressure of the refrigerant circulation loop when the air source heat pump unit is in the cooling condition;

S205: Control the running state of the compressor and the running state of the electronic expansion valve according to the value range of the low pressure;

S206: If the low-pressure pressure is less than the first preset low-pressure pressure and greater than or equal to the second preset low-pressure pressure for the first preset time period, control the operating frequency of the compressor and the opening of the electronic expansion valve to remain unchanged;

S207: If the low-pressure pressure is less than the second preset low-pressure pressure and greater than or equal to the third preset low-pressure pressure for the second preset time period, control the operating frequency of the compressor not to increase and control the opening of the electronic expansion valve to increase ;

S208: If the low-pressure pressure is less than the third preset low-pressure pressure and greater than or equal to the fourth preset low-pressure pressure for a third preset time period, control the operating frequency of the compressor to decrease and control the opening of the electronic expansion valve to increase;

S209: If the low pressure is less than the fourth preset low pressure and lasts for a fourth preset time, control the compressor and the electronic expansion valve to close.

In steps S201 to S203, when the air source heat pump unit starts to start, the controller first controls the circulating water pump 8 to start, preferably after the circulating water pump 8 runs for a preset operation time, then obtains the water flow in the water circulation loop, In order to effectively ensure that the second heat exchanger 5 is filled with enough water, thereby effectively avoiding the phenomenon of "emptying" in the second heat exchanger 5, specifically, if the water flow rate is greater than or equal to the preset water flow rate, then the The controller controls the operation of the refrigerant circulation loop. If the water flow rate is less than the preset water flow rate, the controller controls the circulating water pump 8 to continue to run and controls the refrigerant circulation loop not to run until the water flow rate is greater than Or equal to the preset water flow. In this preferred embodiment, the preset running time is 2 to 3 minutes, and the preset water flow rate is 70% of the standard water flow rate. It should be noted that the acquisition method of the water flow rate can be monitored by the water flow rate, and can also be monitored by the water inflow time. The present invention does not make any limitation on the acquisition method of the water flow rate, and technicians can Self-setting, as a preferred setting method, the present invention monitors the flow rate of water through the flow meter 9, and then obtains the water flow rate in the water circulation circuit, and determines the water flow rate through the water flow rate to ensure that the obtained The accuracy of the water flow rate. It should also be noted that the setting of the standard water flow rate can be the default setting of the air source heat pump unit when it leaves the factory, or it can be set by the user according to the actual operating conditions, and the present invention does not make any restrictions on this , technicians can set it by themselves.

In steps S204 and S205, when the air source heat pump unit is in cooling mode, the low-pressure pressure of the refrigerant circulation circuit is obtained, and the low-pressure pressure sensor 7 can convert the low-pressure pressure into an output signal and transmit it to the A controller; then, the controller controls the operating state of the compressor 1 and the operating state of the electronic expansion valve 4 according to the value range of the low pressure. It should be noted that the present invention does not impose any restrictions on the specific value range of the numerical range, which can be set through multiple tests, or can be set according to the actual operating conditions of the air source heat pump unit, and technicians can Set it yourself according to the actual situation.

In steps S206 to S209, if the low pressure is less than the first preset low pressure and greater than or equal to the second preset low pressure for a first preset duration, the controller controls the operating frequency and The opening of the electronic expansion valve 4 remains unchanged; if the low pressure is greater than or equal to the first preset low pressure, the controller controls the air source heat pump unit to operate according to normal logic, that is, as long as the low pressure The pressure is greater than or equal to the first preset low pressure, the operating parameters of the air source heat pump unit can be adjusted at any time according to actual needs, and the specific control logic is not restrictive; if the low pressure is less than the second The preset low pressure is greater than or equal to the third preset low pressure and lasts for a second preset duration, the controller controls the operating frequency of the compressor 1 not to increase and controls the opening of the electronic expansion valve 4 to increase; if The low pressure is less than the third preset low pressure and greater than or equal to the fourth preset low pressure and lasts for a third preset time, then the controller controls the operating frequency of the compressor 1 to decrease and controls the electronic expansion valve 4 If the low pressure is less than the fourth preset low pressure and lasts for a fourth preset time, the controller controls the compressor 1 and the electronic expansion valve 4 to close, that is, the air source heat pump The unit stops running, thereby effectively ensuring that the second heat exchanger 5 will not be damaged by freezing under refrigeration conditions, thereby effectively ensuring that its service life will not be shortened due to freezing.

It should be noted that the present invention does not impose any restrictions on the specific durations of the first preset duration, the second preset duration, the third preset duration, and the fourth preset duration, which may be the same, It can also be different, and technicians can set it by themselves according to the actual operating conditions of the air source heat pump unit. In this preferred embodiment, obtained through multiple experiments, the specific durations of the first preset duration, the second preset duration, the third preset duration and the fourth preset duration are all 3 Minutes, that is, when the specific time exceeds 3 minutes, the second heat exchanger 5 will face the risk of freezing, but this is not restrictive. For different air source heat pump units, the setting of the specific time Can be different.

It should also be noted that the numerical values of the first preset low pressure, the second preset low pressure, the third preset low pressure and the fourth preset low pressure are not limiting, and technical Personnel can set it by themselves according to the multiple test results of the air source heat pump unit, as long as it is ensured that the second heat exchanger 5 will not be damaged due to freezing.

So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings, however, those skilled in the art will easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

A control method for an air source heat pump unit, characterized in that the air source heat pump unit includes a refrigerant circulation loop, a water circulation loop and an auxiliary electric heating device, and the refrigerant circulation loop is provided with a compressor, a four-way valve, The first heat exchanger, the electronic expansion valve and the second heat exchanger, the water circulation circuit is provided with a circulating water pump, and the refrigerant circulation circuit and the water circulation circuit can realize heat exchange through the second heat exchanger, so The auxiliary electric heating device can heat the water in the water circulation loop, and the control method includes:

When the air source heat pump unit starts to start, the circulating water pump is first controlled to start;

obtaining the water flow rate in the water circulation loop;

If the water flow rate is greater than or equal to the preset water flow rate, control the operation of the refrigerant circulation loop;

When the air source heat pump unit is in heating mode, obtain the outlet water temperature of the water circulation loop;

According to the outlet water temperature, control the operating condition of the refrigerant circulation loop and the on-off state of the auxiliary electric heating device;

Obtaining the low-pressure pressure of the refrigerant circulation loop when the air source heat pump unit is in the cooling condition;

According to the value range of the low pressure, the operating state of the compressor and the electronic expansion valve are controlled.
The control method according to claim 1, wherein the step of "obtaining the outlet water temperature of the water circulation circuit" specifically includes:

When the water circulation circuit is started, the initial outlet water temperature of the water circulation circuit is obtained;

After a preset running time, obtain the current outlet water temperature of the water circulation circuit;

The step of "controlling the operating condition of the refrigerant circulation loop and the opening and closing state of the auxiliary electric heating device according to the outlet water temperature" specifically includes:

According to the initial outlet water temperature and the current outlet water temperature, the operating conditions of the refrigerant circulation loop and the opening and closing states of the auxiliary electric heating device are controlled.
The control method according to claim 2, characterized in that, "control the operating conditions of the refrigerant circulation loop and the opening and closing states of the auxiliary electric heating device according to the initial outlet water temperature and the current outlet water temperature" The steps specifically include:

If the difference between the current outlet water temperature and the initial outlet water temperature is less than or equal to the preset outlet water temperature difference and the current outlet water temperature is less than or equal to the first preset outlet water temperature, then controlling the operating condition of the refrigerant circulation loop is not Change and turn on the auxiliary electric heating device.
The control method according to claim 3, wherein the control method further comprises:

When the auxiliary electric heating device is turned on, obtain the outlet water temperature of the water circulation loop again;

When the outlet water temperature obtained again is greater than a second preset outlet water temperature, turn off the auxiliary electric heating device;

Wherein, the second preset outlet water temperature is greater than the first preset outlet water temperature.
The control method according to claim 4, wherein a high and low pressure pressure balance valve is also provided on the refrigerant circulation circuit, and the control method further comprises:

When the air source heat pump unit starts to operate in the defrosting mode, the four-way valve is controlled to reversing and the high and low pressure balance valve is controlled to open.
The control method according to claim 5, wherein the step of "controlling the opening of the high and low pressure balance valve" specifically includes:

Controlling the high and low pressure pressure balance valve to open a preset protection period.
The control method according to any one of claims 1 to 6, characterized in that, "control the operating state of the compressor and the operating state of the electronic expansion valve according to the value range of the low pressure" The steps include:

If the low-pressure pressure is less than the first preset low-pressure pressure and greater than or equal to the second preset low-pressure pressure for a first preset time period, control the operating frequency of the compressor and the opening of the electronic expansion valve to remain unchanged .
The control method according to claim 7, wherein the step of "controlling the operating state of the compressor and the operating state of the electronic expansion valve according to the numerical range of the low pressure" further includes:

If the low pressure is less than the second preset low pressure and greater than or equal to a third preset low pressure for a second preset time period, control the operating frequency of the compressor not to increase and control the electronic expansion The opening of the valve increases.
The control method according to claim 8, wherein the step of "controlling the operating state of the compressor and the operating state of the electronic expansion valve according to the numerical range of the low pressure" further includes:

If the low-pressure pressure is less than the third preset low-pressure pressure and greater than or equal to a fourth preset low-pressure pressure and lasts for a third preset time period, control the operation frequency of the compressor to decrease and control the electronic expansion valve The opening increases.
The control method according to claim 9, wherein the step of "controlling the operating state of the compressor and the operating state of the electronic expansion valve according to the numerical range of the low pressure" further includes:

If the low pressure is less than the fourth preset low pressure for a fourth preset time period, the compressor and the electronic expansion valve are controlled to be closed.