Control method for air source heat pump unit and air source heat pump unit

Abstract

The invention relates to the technical field of air conditioners, particularly provides a control method for an air source heat pump unit and the air source heat pump unit, and aims to solve the problem that the evaporation temperature of a compressor is difficult to effectively control due to the fact that fan speed control is adopted at the high heating environment temperature in the prior art. In order to achieve the purpose, the control method for the air source heat pump unit comprises the following steps that the outdoor environment temperature Tao, the water outlet temperature Tewo and the air suction pressure saturation temperature Pst during operation of the air source heat pump unit are obtained; the outdoor environment temperature Tao, the water outlet temperature Tewo and the suction pressure saturation temperature Pst are compared with corresponding threshold values, and corresponding comparison results are obtained; and according to the corresponding comparison result, the air source heat pump unit operates in a single-valve mode or a double-valve mode, so that the heat exchange area of the evaporator is changed, effective control over the evaporation temperature of the compressor at the high environment temperature is achieved, and it is ensured that the air source heat pump unit can normally heat in the high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and specifically provides a control method for an air source heat pump unit and an air source heat pump unit. Background Art

[0002] Air source heat pump units include single-stage compressed air source heat pump units, cascade air source heat pump units and air source heat pump hot water units. The above-mentioned air source heat pump units mainly rely on the evaporator to absorb heat from the air. The higher the air temperature, the higher the evaporation temperature of the evaporator, that is, the higher the evaporation temperature of the compressor. However, the compressor has a maximum limit on the evaporation temperature. If the compressor evaporation temperature exceeds the limit, it may cause poor heat dissipation of the motor and cause damage to the compressor.

[0003] At present, the highest heating environment temperature in the industry (hereinafter referred to as heating ambient temperature) is generally 50℃ ambient temperature, and it is impossible to achieve 55℃ ambient temperature heating. Under the existing high ambient temperature conditions, the evaporation temperature is controlled by adjusting the fan speed, that is, when the evaporation temperature is high, the fan is downshifted, but it can only meet the compressor evaporation temperature control below 50℃ ambient temperature. When the ambient temperature is above 50℃, the control effect of the above control method is poor, not only the evaporation temperature response is slow, but also the control process may exceed the evaporation temperature limit.

[0004] Therefore, it is urgent to develop a control method for an air source heat pump unit and an air source heat pump unit to solve the above problems. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem in the prior art that it is difficult to effectively control the evaporation temperature of the compressor by using fan speed control under high heating ambient temperature.

[0006] In a first aspect, the present invention provides a control method for an air source heat pump unit, wherein the air source heat pump unit comprises two throttling branches connected in parallel, each throttling branch comprises a corresponding throttling valve, and the air source heat pump unit operates in a dual valve mode or a single valve mode by controlling the two throttling branches to be turned on or one of them to be turned on. The control method comprises the following steps:

[0007] Obtaining the outdoor ambient temperature Tao, the water outlet temperature Tewo and the suction pressure saturation temperature Pst when the air source heat pump unit is running;

[0008] Compare the outdoor ambient temperature Tao, the outlet water temperature Tewo and the suction pressure saturation temperature Pst with corresponding thresholds, and obtain corresponding comparison results;

[0009] According to the corresponding comparison result, the air source heat pump unit is operated in the single valve mode or the double valve mode.

[0010] In the preferred technical solution of the above control method, the corresponding thresholds include: a first ambient temperature threshold Ta1, a first outlet water temperature threshold and a first suction pressure saturation temperature threshold p1, wherein the first outlet water temperature threshold is calculated by the formula a1*Tao+b1, a1 and b1 are fitting formula coefficients,

[0011] The step of “causing the air source heat pump unit to operate in the single valve mode or the double valve mode according to the corresponding comparison result” specifically includes:

[0012] When the corresponding comparison result satisfies

[0013] Tao>Ta1,

[0014] Tewo>a1*Tao+b1, and

[0015] Pst ≥ p1,

[0016] When the three conditions are met, the air source heat pump unit is operated in the single valve mode and the above steps are repeated.

[0017] In the preferred technical solution of the above control method, the value of Ta1 is 40°C±2°C, and the value of p1 is 15°C±1°C.

[0018] In the preferred technical solution of the above control method, the value of Ta1 is 40°C, and the value of p1 is 15°C.

[0019] In the preferred technical solution of the above control method, the air source heat pump unit also includes a fan, and the fan has two fan speeds, fan1 and fan2. <fan2,

[0020] The control method further includes: adjusting the rotation speed of the fan to the rotation speed of the fan1 fan.

[0021] In the preferred technical solution of the above control method, the corresponding thresholds also include: a second ambient temperature threshold Ta2, a second outlet water temperature threshold and a second suction pressure saturation temperature threshold p2, wherein the second outlet water temperature threshold is calculated by the formula a2*Tao+b2, a2 ​​and b2 are fitting formula coefficients, Ta1>Ta2, p1>p2,

[0022] The step of “causing the air source heat pump unit to operate in the single valve mode or the double valve mode according to the corresponding comparison result” specifically includes:

[0023] When the corresponding comparison result satisfies

[0024] Tao <Ta2,

[0025] Tewo < a2 * Tao + b2, or

[0026] Pst ≤ p2,

[0027] When one of the three conditions is met, change the operation mode of the air source heat pump unit from the single-valve mode to the double-valve mode.

[0028] In a preferred technical solution of the above control method, the value of Ta2 is 35°C ± 2°C, and the value of p2 is 12°C ± 1°C.

[0029] In a preferred technical solution of the above control method, the value of Ta2 is 35°C, and the value of p2 is 12°C.

[0030] In a preferred technical solution of the above control method, the air source heat pump unit further includes a fan, and the fan has two fan speeds, fan1 and fan2, where fan1 < fan2.

[0031] The control method further includes: adjusting the speed of the fan to the fan2 speed.

[0032] In a second aspect, the present invention also provides an air source heat pump unit, which includes a controller configured to execute the above control method for the air source heat pump unit.

[0033] In the case of adopting the above technical solutions, the control method for the air source heat pump unit and the air source heat pump unit of the present invention compare the outdoor ambient temperature Tao, the water outlet temperature Tewo, and the suction pressure saturation temperature Pst with the corresponding thresholds, and according to the corresponding comparison results, make the air source heat pump unit operate in the single-valve mode or the double-valve mode. By controlling the single and double valves, the heat transfer area of the evaporator is changed, that is, the heat transfer area of the evaporator is reduced in the single-valve mode, and the heat transfer area of the evaporator is increased in the double-valve mode, so as to effectively control the evaporation temperature of the compressor at high ambient temperatures, that is, make the evaporation temperature respond quickly, and the control process can significantly reduce the situation of exceeding the evaporation temperature limit value, thereby preventing the compressor from being damaged and ensuring that the air source heat pump unit can operate normally for heating in a high-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The following describes the preferred embodiments of the present invention with reference to the drawings, in which:

[0035] Figure 1 is a schematic structural diagram of an air source heat pump unit according to an embodiment of the present invention;

[0036] Figure 2 is a schematic flow chart of a control method for an air source heat pump unit according to an embodiment of the present invention;

[0037] Figure 3 It is a schematic control diagram of an air source heat pump unit according to an embodiment of the present invention.

[0038] The symbols in the figure mean the following:

[0039] 1 first liquid separator, 2 second liquid separator, 3 first throttle valve LEV1, 4 second throttle valve LEV2, 5 second heat exchanger, 6 four-way valve, 7 compressor, 8 gas-liquid separator, 9 first heat exchanger, 10 first filter, 11 second filter, 12 third filter,

[0040] C, D, E, and F represent the four ports of the four-way valve. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application. For example, although the various steps are described in a sequential order in the following embodiments, it is understood by those skilled in the art that in order to achieve the effect of the present embodiment, it is not necessary to perform in such an order between different steps, and they can be performed simultaneously (in parallel) or in a reversed order, and these simple changes are within the scope of protection of the present application.

[0042] The present invention aims to solve the problem in the prior art that it is difficult to effectively control the evaporation temperature of the compressor by adopting fan wind speed control under high heating environment temperature.

[0043] Figure 1 FIG. 1 is a schematic structural diagram of an air source heat pump unit according to an embodiment of the present invention. Figure 1As shown, the air source heat pump unit can generally include a compressor 7, a four-way valve 6, a first heat exchanger 9, a first throttling branch (not marked in the figure), a second throttling branch (not marked in the figure), a second heat exchanger 5 and a gas-liquid separator 8. Under the heating condition, the first heat exchanger 9 is a condenser, the first heat exchanger 9 can be a water-side heat exchanger, the second heat exchanger 5 is an evaporator, and the second heat exchanger 5 can be a finned heat exchanger. The first throttling branch and the second throttling branch are connected in parallel. The first throttling branch includes a first throttling valve LEV13, a first liquid distributor 1 and a connecting pipeline. The second throttling branch includes a second throttling valve LEV24, a second liquid distributor 2 and a connecting pipeline. The four-way valve 6 includes a C port, a D port, an E port and a F port. The air outlet of the compressor 7 is connected to the F port of the four-way valve 6, and the F port of the four-way valve 6 is connected to the E port. The E port of the four-way valve 6 is connected to the inlet of the first heat exchanger 9. The outlet of the first heat exchanger 9 is connected in parallel with the first throttling branch and the second throttling branch. The first throttling branch and the second throttling branch are connected to the second heat exchanger 5 accordingly. The outlet of the second heat exchanger 5 is connected to the C port of the four-way valve 6, and the C port of the four-way valve 6 is connected to the D port. The D port of the four-way valve 6 is connected to the gas-liquid separator 8, and the gas-liquid separator 8 is connected to the air inlet of the compressor 7. By controlling the first throttling branch and the second throttling branch to be turned on, the air source heat pump unit operates in a dual-valve mode. By controlling one of the first throttling branch and the second throttling branch to be turned on, the air source heat pump unit operates in a single-valve mode. Among them, a first filter 10 is provided after the first heat exchanger 9 and before the first throttling branch and the second throttling branch, a second filter 11 is provided between the first throttling valve LEV13 and the first liquid distributor 1, and a third filter 12 is provided between the second throttling valve LEV24 and the second liquid distributor 2.

[0044] Dual valve mode

[0045] The high-temperature refrigerant gas discharged from the air outlet of the compressor 7 enters the E port through the F port of the four-way valve 6, and then enters the first heat exchanger 9 through the E port of the four-way valve 6 to release heat and condense into a refrigerant liquid. It passes through the first throttle valve LEV13 and the second throttle valve LEV24 in the parallel first throttling branch and the second throttling branch for throttling, and then enters the corresponding second heat exchanger 5 through the first liquid separator 1 and the second liquid separator 2 to absorb heat. The refrigerant absorbs heat and evaporates. The gaseous refrigerant passes through the C port, D port of the four-way valve 6 and the gas-liquid separator 8 to enter the air inlet of the compressor 7 to be compressed again.

[0046] Single valve mode

[0047] The high-temperature refrigerant gas discharged from the outlet of the compressor 7 enters through port F of the four-way valve 6 into port E, and then enters the first heat exchanger 9 through port E of the four-way valve 6 to release heat and condense into a refrigerant liquid. It undergoes throttling through the second throttle valve LEV24 in the second throttle branch, and then enters the second heat exchanger 5 through the second liquid distributor 2 to absorb heat. The refrigerant absorbs heat and evaporates, and the gaseous refrigerant enters the inlet of the compressor 7 through ports C, D of the four-way valve 6 and the gas-liquid separator 8 and is compressed again.

[0048] Certainly, the single-valve mode can also be to only operate the first throttle branch, that is, to perform throttling through the first throttle valve LEV13 in the first throttle branch, and then enter the second heat exchanger 5 through the first liquid distributor 1 to absorb heat, and other working processes remain unchanged.

[0049] During specific implementation, the air source heat pump unit further includes a fan. The fan is installed above the second heat exchanger 5. The fan has two fan speeds, fan1 and fan2, where fan1 < fan2. The first throttle branch and the second throttle branch are arranged vertically. In the single-valve mode, the second throttle branch farther away from the fan is preferentially selected to be opened, that is, only the second throttle branch is operated.

[0050] Figure 2 It is a schematic flowchart of a control method for an air source heat pump unit according to an embodiment of the present invention. The present invention provides a control method for an air source heat pump unit. The air source heat pump unit includes two parallel throttle branches, and each throttle branch includes a corresponding throttle valve. By controlling the conduction of the two throttle branches or the conduction of one of them, the air source heat pump unit operates in a double-valve mode or a single-valve mode. The control method includes the following steps:

[0051] S100, obtain the outdoor ambient temperature Tao, the outlet water temperature Tewo, and the suction pressure saturation temperature Pst when the air source heat pump unit is operating;

[0052] S200, compare the outdoor ambient temperature Tao, the outlet water temperature Tewo, and the suction pressure saturation temperature Pst with the corresponding thresholds, and obtain the corresponding comparison results;

[0053] S300, according to the corresponding comparison results, make the air source heat pump unit operate in a single-valve mode or a double-valve mode.

[0054] In the case of adopting the above technical scheme, the control method for an air source heat pump unit of the present invention compares the outdoor ambient temperature Tao, the outlet water temperature Tewo and the suction pressure saturation temperature Pst with the corresponding threshold values, and according to the corresponding comparison results, enables the air source heat pump unit to operate in a single valve mode or a double valve mode, and changes the heat exchange area of ​​the evaporator by controlling the single and double valves, that is, reducing the heat exchange area of ​​the evaporator in the single valve mode and increasing the heat exchange area of ​​the evaporator in the double valve mode, thereby achieving effective control of the evaporation temperature of the compressor under high ambient temperature, that is, making the evaporation temperature respond faster, and the control process can significantly reduce the situation of exceeding the evaporation temperature limit value, thereby preventing damage to the compressor and ensuring that the air source heat pump unit can heat normally in a high temperature environment.

[0055] In a preferred embodiment of the above control method, the corresponding thresholds in step S200 include: a first ambient temperature threshold Ta1, a first outlet water temperature threshold and a first suction pressure saturation temperature threshold p1, wherein the first outlet water temperature threshold is calculated by the formula a1*Tao+b1, a1 and b1 are fitting formula coefficients,

[0056] The step of “S300, operating the air source heat pump unit in a single valve mode or a double valve mode according to the corresponding comparison result” specifically includes:

[0057] When the corresponding comparison result satisfies

[0058] Tao>Ta1,

[0059] Tewo>a1*Tao+b1, and

[0060] Pst ≥ p1,

[0061] When the three conditions are met, operate the air source heat pump unit in single valve mode and repeat the above steps.

[0062] In specific implementation, the single valve operation mode may be to operate only the second throttle branch, that is, to maintain the opening of the second throttle valve LEV24 at a certain set opening, and adjust the opening of the first throttle valve LEV13 to 0.

[0063] Of course, the single valve mode of operation can be to operate only the first throttle branch, that is, to keep the opening of the first throttle valve LEV13 at a certain set opening, and adjust the opening of the second throttle valve LEV24 to 0.

[0064] In specific implementation, the coefficients of the fitting formula a1 and b1 can be determined according to the actual test values. For example, when Tao = 40 ° C, the test value of the corresponding reasonable related point Tewo, and when Tao = 50 ° C, the test value of the corresponding reasonable related point Tewo, the above values ​​are substituted into the formula Tewo = a1*Tao+b1 to calculate the values ​​of a1 and b1, so as to obtain the "Tewo = a1*Tao+b1" data line with the horizontal coordinate Tao and the vertical coordinate Tewo, through which the first outlet water temperature threshold can be obtained.

[0065] In a preferred implementation of the above control method, Ta1 is set to 40°C±2°C, and p1 is set to 15°C±1°C.

[0066] In a specific implementation, Ta1 is 42° C., 41.8° C., 41.7° C., 41.6° C., 41.5° C., 41.3° C., 41.2° C., 41.1° C., 41° C., 40.5° C. or 40.0° C. p1 is 16° C., 15.5° C., 15° C., 14.5° C. or 14° C.

[0067] In a preferred embodiment of the above control method, Ta1 is 40°C and p1 is 15°C.

[0068] For example, when the air source heat pump unit is running, the outdoor ambient temperature Tao = 45 ° C, the outlet water temperature Tewo = 50 ° C, and the suction pressure saturation temperature Pst = 17 ° C. Assuming Ta1 = 40 ° C, a1*Tao+b1 = 35 ° C, p1 = 15 ° C, by comparison:

[0069] Tao>40℃, that is, Tao>Ta1,

[0070] Tewo>a1*Tao+b1,

[0071] Pst>15, that is, Pst≥p1,

[0072] When the above three conditions are met, the operation mode of the air source heat pump unit is changed to single valve control.

[0073] For example, when the air source heat pump unit is running, the outdoor ambient temperature Tao = 39 ° C, the outlet water temperature Tewo = 45 ° C, and the suction pressure saturation temperature Pst = 16 ° C. Assuming Ta1 = 40 ° C, a1*Tao+b1 = 35 ° C, p1 = 15 ° C, by comparison:

[0074] Tao<40℃, that is Tao <Ta1,

[0075] Tewo>a1*Tao+b1,

[0076] Pst>15, that is, Pst≥p1,

[0077] If the above three conditions are not met, the air source heat pump unit maintains the dual-valve control mode.

[0078] In a preferred embodiment of the above control method, when the air source heat pump unit operates in the single-valve control mode, the control method further includes: adjusting the speed of the fan to the fan speed of fan1.

[0079] In a preferred embodiment of the above control method, the corresponding thresholds in step S200 further include: the second ambient temperature threshold Ta2, the second outlet water temperature threshold, and the second suction pressure saturation temperature threshold p2. Among them, the second outlet water temperature threshold is obtained by calculating with the formula a2*Tao + b2, where a2 and b2 are fitting formula coefficients, Ta1 > Ta2, p1 > p2.

[0080] The step of "S300 enables the air source heat pump unit to operate in the single-valve mode or the dual-valve mode according to the corresponding comparison result" specifically further includes:

[0081] When the corresponding comparison result satisfies

[0082] Tao < Ta2,

[0083] Tewo < a2*Tao + b2, or

[0084] Pst ≤ p2,

[0085] When one of the three conditions is met, the operation mode of the air source heat pump unit is changed from the single-valve mode to the dual-valve mode.

[0086] During specific implementation, when operating in the dual-valve mode, it can be from the original operation of the second throttling branch, that is, while maintaining the opening of the second throttle valve LEV24, adjusting the opening of the first throttle valve LEV13 from 0 to the initial opening at the corresponding ambient temperature.

[0087] Of course, when operating in the dual-valve mode, it can be from the original operation of the first throttling branch, that is, while maintaining the opening of the first throttle valve LEV13, adjusting the opening of the second throttle valve LEV24 from 0 to the initial opening at the corresponding ambient temperature.

[0088] During specific implementation, the fitting formula coefficients a2 and b2 can be determined according to actual test values. For example, take the test values of the reasonable relevant point Tewo when Tao = 35°C, and take the test values of the reasonable relevant point Tewo when Tao = 45°C. Substitute the above values into the formula Tewo = a2*Tao + b2 to calculate the values of a2 and b2, so as to obtain the data line of "Tewo = a2*Tao + b2" with Tao as the abscissa and Tewo as the ordinate. The second outlet water temperature threshold can be obtained through this data line.

[0089] In a preferred implementation of the above control method, Ta2 is 35°C±2°C, and p2 is 12°C±1°C.

[0090] In a specific implementation, Ta2 is 37° C., 36.5° C., 36° C., 35.° C., 35° C., 34.5° C., 34° C., 33.5° C. or 33° C. p2 is 13° C., 12.5° C., 12° C., 11.5° C. or 11° C.

[0091] In a preferred embodiment of the above control method, Ta2 is 35°C and p2 is 12°C.

[0092] For example, when the air source heat pump unit is running, the outdoor ambient temperature Tao = 25 ° C, the outlet water temperature Tewo = 50 ° C, and the suction pressure saturation temperature Pst = 14 ° C. Assuming Ta2 = 35 ° C, a2*Tao+b2 = 80 ° C, p2 = 12 ° C, by comparison:

[0093] Tao<35, that is, Tao<Ta2,

[0094] Tewo<a2*Tao+b2,

[0095] Pst>p2,

[0096] If the corresponding comparison result meets the two conditions, the operation mode of the air source heat pump unit is changed from the single-valve mode to the double-valve mode.

[0097] For example, when the air source heat pump unit is running, the outdoor ambient temperature Tao = 30 ° C, the outlet water temperature Tewo = 65 ° C, and the suction pressure saturation temperature Pst = 13 ° C. Assuming Ta2 = 35 ° C, a2*Tao+b2 = 60 ° C, p2 = 12 ° C, by comparison:

[0098] Tao<35, that is, Tao<Ta2,

[0099] Tewo>a2*Tao+b2,

[0100] Pst>p2,

[0101] If the corresponding comparison result meets one condition, the operation mode of the air source heat pump unit is changed from the single-valve mode to the double-valve mode.

[0102] In a preferred implementation of the above control method, when the operation mode of the air source heat pump unit is changed from the single valve mode to the double valve mode, the control method further comprises: adjusting the speed of the fan to the fan2 fan speed.

[0103] Figure 3: is a schematic control diagram of an air source heat pump unit according to an embodiment of the present invention. The present invention also provides an air source heat pump unit, the air source heat pump unit includes a controller, and the controller is configured to execute the above control method for the air source heat pump unit. The control method includes the following steps:

[0104] S100, obtaining the outdoor ambient temperature Tao, the outlet water temperature Tewo and the suction pressure saturation temperature Pst when the air source heat pump unit is running;

[0105] S200, comparing the outdoor ambient temperature Tao, the outlet water temperature Tewo and the suction pressure saturation temperature Pst with corresponding thresholds, and obtaining corresponding comparison results;

[0106] S300: According to the corresponding comparison result, the air source heat pump unit is operated in a single valve mode or a double valve mode.

[0107] In the case of adopting the above technical scheme, the air source heat pump unit of the present invention compares the outdoor ambient temperature Tao, the outlet water temperature Tewo and the suction pressure saturation temperature Pst with the corresponding threshold values, and according to the corresponding comparison results, enables the air source heat pump unit to operate in single-valve mode or double-valve mode, and changes the heat exchange area of ​​the evaporator by controlling the single and double valves, that is, reducing the heat exchange area of ​​the evaporator in the single-valve mode and increasing the heat exchange area of ​​the evaporator in the double-valve mode, thereby realizing effective control of the evaporation temperature of the compressor under high ambient temperature, that is, making the evaporation temperature respond faster, and the control process can significantly reduce the situation of exceeding the evaporation temperature limit value, thereby preventing damage to the compressor and ensuring that the air source heat pump unit can heat normally in a high temperature environment.

[0108] In a preferred embodiment of the above-mentioned air source heat pump unit, the air source heat pump unit also includes a temperature sensor, which is correspondingly installed on the first heat exchanger 9 and the second heat exchanger 5. The corresponding temperature sensors are used to obtain the outdoor ambient temperature Tao and the water outlet temperature Tewo, and transmit the temperature data to the controller.

[0109] In the preferred embodiment of the above-mentioned air source heat pump unit, the control method for the air source heat pump unit executed by the controller, the corresponding thresholds in step S200 include: a first ambient temperature threshold Ta1, a first outlet water temperature threshold and a first suction pressure saturation temperature threshold p1, wherein the first outlet water temperature threshold is calculated by the formula a1*Tao+b1, a1 and b1 are fitting formula coefficients,

[0110] The step of “S300, operating the air source heat pump unit in a single valve mode or a double valve mode according to the corresponding comparison result” specifically includes:

[0111] When the corresponding comparison result satisfies

[0112] Tao > Ta1,

[0113] Tewo > a1 * Tao + b1, and

[0114] Pst ≥ p1,

[0115] When the above three conditions are met, the air source heat pump unit operates in the single - valve mode and the above steps are repeated.

[0116] Among them, Ta1 takes a value of 40°C ± 2°C, and p1 takes a value of 15°C ± 1°C.

[0117] In the preferred embodiment of the above air source heat pump unit, when the air source heat pump unit operates in the single - valve control mode, the control method further includes: adjusting the speed of the fan to the fan speed of fan1.

[0118] In the preferred embodiment of the above air source heat pump unit, for the control method of the air source heat pump unit executed by the controller, the corresponding thresholds in step S200 further include: the second ambient temperature threshold Ta2, the second outlet water temperature threshold, and the second suction pressure saturation temperature threshold p2. Among them, the second outlet water temperature threshold is obtained by calculating with the formula a2 * Tao + b2, where a2 and b2 are fitting formula coefficients, Ta1 > Ta2, p1 > p2,

[0119] The step of "S300 enables the air source heat pump unit to operate in the single - valve mode or the double - valve mode according to the corresponding comparison result" specifically further includes:

[0120] When the corresponding comparison result satisfies

[0121] Tao < Ta2,

[0122] Tewo < a2 * Tao + b2, or

[0123] Pst ≤ p2,

[0124] When one of the above three conditions is met, the operation mode of the air source heat pump unit is changed from the single - valve mode to the double - valve mode.

[0125] Among them, Ta2 takes a value of 35°C ± 2°C, and p2 takes a value of 12°C ± 1°C.

[0126] In the preferred embodiment of the above air source heat pump unit, for the control method of the air source heat pump unit executed by the controller, when the operation mode of the air source heat pump unit is changed from the single - valve mode to the double - valve mode, the control method further includes: adjusting the speed of the fan to the fan speed of fan2.

[0127] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims of the present application, any one of the claimed embodiments may be used in any combination.

[0128] It should be noted that although the detailed steps of the method of the present application are described in detail above, without departing from the basic principles of the present application, technical personnel in this field can combine, split and change the order of the above steps. The modified technical solution does not change the basic concept of the present application and therefore falls within the scope of protection of the present application.

[0129] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A control method for an air source heat pump unit, characterized in that: The air source heat pump unit includes two throttling branches connected in parallel. Each throttling branch includes a corresponding throttle valve. By controlling the conduction of the two throttling branches or one of them, the air source heat pump unit operates in a dual-valve mode or a single-valve mode. The control method includes the following steps: Obtain the outdoor ambient temperature Tao, the outlet water temperature Tewo, and the suction pressure saturation temperature Pst when the air source heat pump unit is operating. Compare the outdoor ambient temperature Tao, the outlet water temperature Tewo, and the suction pressure saturation temperature Pst with corresponding thresholds, and obtain corresponding comparison results. According to the corresponding comparison results, make the air source heat pump unit operate in the single-valve mode or the dual-valve mode.

2. The control method according to claim 1, characterized in that: The corresponding thresholds include: the first ambient temperature threshold Ta1, the first outlet water temperature threshold, and the first suction pressure saturation temperature threshold p1. Among them, the first outlet water temperature threshold is obtained by calculating with the formula a1*Tao + b1, where a1 and b1 are fitting formula coefficients. The step of "According to the corresponding comparison results, make the air source heat pump unit operate in the single-valve mode or the dual-valve mode" specifically includes: When the corresponding comparison results satisfy Tao>Ta1, Tewo>a1*Tao + b1, and Pst≥p1, When all three conditions are met, make the air source heat pump unit operate in the single-valve mode and repeat the above steps.

3. The control method according to claim 2, characterized in that: The value of Ta1 is 40℃±2℃, and the value of p1 is 15℃±1℃.

4. The control method according to claim 3, characterized in that: The value of Ta1 is 40℃, and the value of p1 is 15℃.

5. The control method according to any one of claims 2 to 4, characterized in that: The air source heat pump unit further includes a fan, and the fan has two fan speeds, fan1 and fan2, where fan1 < fan2. The control method further includes: adjusting the speed of the fan to the fan1 speed.

6. The control method according to claim 2, characterized in that: The corresponding thresholds further include: the second ambient temperature threshold Ta2, the second outlet water temperature threshold, and the second suction pressure saturation temperature threshold p2. Among them, the second outlet water temperature threshold is obtained by calculating with the formula a2*Tao + b2, where a2 and b2 are fitting formula coefficients, Ta1>Ta2, p1>p2. The step of "According to the corresponding comparison results, make the air source heat pump unit operate in the single-valve mode or the dual-valve mode" specifically further includes: When the corresponding comparison results satisfy Tao < Ta2, Tewo < a2*Tao + b2, or Pst≤p2, When any one of the three conditions is met, change the operation mode of the air source heat pump unit from the single-valve mode to the dual-valve mode.

7. The control method according to claim 6, characterized in that: The value of Ta2 is 35℃±2℃, and the value of p2 is 12℃±1℃.

8. The control method according to claim 7, characterized in that: The value of Ta2 is 35℃, and the value of p2 is 12℃.

9. The control method according to any one of claims 6 to 8, characterized in that: The air source heat pump unit further includes a fan, and the fan has two fan speeds, fan1 and fan2, fan1 < fan2. The control method further includes: adjusting the speed of the fan to the fan2 speed.

10. An air source heat pump unit, characterized in that: The air source heat pump unit includes a controller, and the controller is configured to execute the control method for the air source heat pump unit according to any one of claims 1-9.

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