Expansion valve control method and heat pump device

Abstract

This invention belongs to the technical field of heat pump devices, and discloses an expansion valve control method and a heat pump device. The expansion valve control method includes: S1, acquiring ambient temperature, exhaust temperature, and return gas temperature; S2, calculating suction superheat, exhaust superheat, and subcooling; S3, calculating target suction superheat, target exhaust superheat, target subcooling, and target coil temperature; S4, calculating temperature deviations; if all temperature deviations are greater than zero, proceed to S5; if all temperature deviations are less than zero, proceed to S6; otherwise, proceed to S7; S5, calculating the valve adjustment amount based on the maximum value of the temperature deviations and adjusting the valve opening; S6, calculating the valve adjustment amount based on the minimum value of the temperature deviations and adjusting the valve closing; S7, calculating the weight of each temperature, determining the direction of expansion valve action based on the maximum value of each temperature weight, and determining the valve adjustment amount based on the temperature deviation. This heat pump device can improve the accuracy of regulation and avoid the limitations and lag of traditional expansion valve control methods.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and more particularly to an expansion valve control method and a heat pump device. Background Technology

[0002] The expansion valve is a key component in a heat pump system, and also one of the four main components of a heat pump system; the other three key components are the compressor, condenser, and evaporator. As a throttling element in a heat pump system, the expansion valve regulates the refrigerant flow by adjusting the valve opening, thereby changing the amount of refrigerant entering the evaporator or condenser, and thus altering the heating or cooling effect.

[0003] The opening degree of the expansion valve affects the cooling and heating capacity of the air conditioner, as well as the lifespan of the compressor, thus indirectly affecting user comfort. Traditional methods for controlling the expansion valve are mostly based on return gas superheat or exhaust gas superheat. These two methods are simplistic and limited, and the adjustment process is lagging, unable to quickly adapt to changes in the surrounding environment, thereby leading to a decrease in heat pump performance. Summary of the Invention

[0004] The purpose of this invention is to provide an expansion valve control method and a heat pump device, which can improve the accuracy of control and regulation and avoid the limitations and lag of expansion valve control methods.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] Expansion valve control methods include:

[0007] S1. At preset intervals, acquire ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, inlet water temperature Ti, liquid pipe temperature Tip, and coil temperature Tdef.

[0008] S2. Calculate the intake superheat Tsh, exhaust superheat Tdsh, and subcooling Tlsh respectively; where Tsh = Ts - Tdef, Tdsh = Td - To, and Tlsh = To - Tip;

[0009] S3. Calculate the target intake superheat ΔTsh, target exhaust superheat ΔTdsh, target subcooling ΔTlsh, and target coil temperature ΔTdef respectively.

[0010] Where, ΔTsh=a; ΔTdsh=(0.5To+15)·(-0.003Ta+1.008); ΔTlsh=b(0.01To+A1)·(-0.01Ta+A2); ΔTdef=c; a, b, c, A1 and A2 are all constants;

[0011] S4. Calculate the temperature deviation α, which includes the intake superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4; where α1 = Tsh - ΔTsh, α2 = Tdsh - ΔTdsh, α3 = Tlsh - ΔTlsh, and α4 = Tdef - ΔTdef.

[0012] If the intake superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4 are all greater than zero, then proceed to step S5.

[0013] If the intake superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4 are all less than zero, then proceed to step S6.

[0014] If the intake superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4 are not all greater than zero or all less than zero, then proceed to step S7.

[0015] S5. Select the maximum value d among the intake superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4, calculate the valve adjustment amount ΔP1 of the expansion valve based on the maximum value d, and adjust the valve opening of the expansion valve.

[0016] S6. Select the minimum value e among the intake superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4, calculate the valve adjustment amount ΔP2 of the expansion valve based on the minimum value e, and adjust the expansion valve to close.

[0017] S7. Calculate the intake superheat weight β1, exhaust superheat weight β2, subcooling weight β3, and coil temperature weight β4 respectively; where β1=9∣ΔTsh∣, β2=8∣ΔTdsh∣, β3=15∣ΔTlsh∣, β4=10∣ΔTdef∣;

[0018] The direction of the expansion valve's operation is determined based on the maximum value f among the intake superheat weight β1, the exhaust superheat weight β2, the subcooling weight β3, and the coil temperature weight β4, and the valve adjustment amount ΔP3 of the expansion valve is determined based on the temperature deviation α.

[0019] Preferably, in step S7, determining the operating direction of the expansion valve based on the maximum value f among the intake superheat weight β1, the exhaust superheat weight β2, the subcooling weight β3, and the coil temperature weight β4, and determining the valve adjustment amount ΔP3 of the expansion valve based on the temperature deviation α, includes:

[0020] Determine the action temperature deviation α corresponding to the maximum value f. n The temperature deviation α of the action n It is a value among the temperature deviations α;

[0021] Based on the intake superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4, the valve adjustment amount ΔQ1, ΔQ2, ΔQ3, and ΔQ4 of the expansion valve are calculated respectively.

[0022] If the temperature deviation of the action is α n If the value is greater than zero, the maximum value among the valve adjustment amount ΔQ1, valve adjustment amount ΔQ2, valve adjustment amount ΔQ3, and valve adjustment amount ΔQ4 is selected as the valve adjustment amount ΔP3, and the expansion valve is adjusted to open.

[0023] If the temperature deviation of the action is α n If the value is less than zero, the minimum value among the valve adjustment amount ΔQ1, valve adjustment amount ΔQ2, valve adjustment amount ΔQ3, and valve adjustment amount ΔQ4 is selected as the valve adjustment amount ΔP3, and the expansion valve is closed for adjustment.

[0024] If the temperature deviation of the action is α n If the value is zero, then the expansion valve has no regulating action.

[0025] Preferably, a PID controller is used to calculate the valve adjustment amount ΔP1, the valve adjustment amount ΔP2, and the valve adjustment amount ΔP3.

[0026] The heat pump device is controlled using the expansion valve control method described above.

[0027] Preferably, the heat pump device includes an ambient temperature sensor, an exhaust temperature sensor, a return gas temperature sensor, an outlet water temperature sensor, an inlet water temperature sensor, a liquid pipe temperature sensor, a coil temperature sensor, and a PID controller.

[0028] The ambient temperature sensor is used to monitor the temperature of the external environment of the heat pump device; the exhaust temperature sensor is located at the exhaust port of the compressor; the return gas temperature sensor is located at the inlet of the compressor; the outlet water temperature sensor is located at the outlet of the condenser; the inlet water temperature sensor is located at the return water port of the condenser; the liquid pipe temperature sensor is located on the connecting pipe between the condenser and the expansion valve; the coil temperature sensor is located on the connecting pipe between the expansion valve and the evaporator.

[0029] The PID controller is connected to the ambient temperature sensor, the exhaust temperature sensor, the return gas temperature sensor, the outlet water temperature sensor, the inlet water temperature sensor, the liquid pipe temperature sensor, and the coil temperature sensor, respectively. The PID controller is also connected to the expansion valve.

[0030] The beneficial effects of this invention are as follows:

[0031] The expansion valve control method provided by this invention obtains the suction superheat Tsh, exhaust superheat Tdsh, and subcooling Tlsh, and calculates the target suction superheat ΔTsh, target exhaust superheat ΔTdsh, target subcooling ΔTlsh, and target coil temperature ΔTdef respectively, thereby obtaining the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4. Then, based on these four deviation values, the control mode of the expansion valve is selected and the specific valve adjustment is calculated. Since the suction superheat Tsh, exhaust superheat Tdsh, subcooling Tlsh, and target suction superheat Tsh are all within the range of ΔTsh, ΔTdsh, and ΔTdef, the control method of the expansion valve is determined. State parameters such as gas superheat ΔTsh and target exhaust superheat ΔTdsh are calculated from temperatures such as ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, and inlet water temperature Ti. Therefore, this expansion valve control method provides a more comprehensive characterization and reflection of the working state of the heat pump unit. It can provide four control modes: suction superheat control, exhaust superheat control, subcooling control, and coil temperature control. It can make real-time adjustments based on the working conditions of the heat pump unit, avoiding the single control mode and lag, improving the accuracy of control and adjustment, and thus further improving the performance of the heat pump.

[0032] The heat pump device provided by this invention, using the expansion valve control method, can automatically adjust in real time according to its own working conditions, avoiding the singleness and lag of the control method, and can quickly adapt to changes in the surrounding environment, thus improving the accuracy of control and adjustment. Attached Figure Description

[0033] Figure 1 This is a flowchart of the expansion valve control method provided in a specific embodiment of the present invention. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] In the description of this embodiment, the terms "upper," "lower," "right," and "left," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0038] like Figure 1 As shown, the present invention provides an expansion valve control method, which includes:

[0039] S1. At preset intervals, acquire ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, inlet water temperature Ti, liquid pipe temperature Tip, and coil temperature Tdef. In this embodiment, the heat pump device is equipped with multiple temperature sensors and a PID controller. The PID (Proportion Integration Differentiation) controller is connected to the temperature sensors. The multiple temperature sensors can respectively measure the ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, inlet water temperature Ti, liquid pipe temperature Tip, and coil temperature Tdef. The ambient temperature Ta is the temperature of the external environment of the heat pump device, the exhaust temperature Td is the temperature at the compressor exhaust port, the return gas temperature Ts is the temperature at the compressor inlet, the outlet water temperature To is the temperature at the condenser outlet, the inlet water temperature Ti is the temperature at the condenser return water port, the liquid pipe temperature Tip is the temperature in the connecting pipe between the condenser and the expansion valve, and the coil temperature Tdef is the temperature in the connecting pipe between the expansion valve and the evaporator. The multiple temperature sensors measure the above temperatures and transmit the temperature signals to the PID controller at preset time intervals.

[0040] S2. Calculate the intake superheat Tsh, exhaust superheat Tdsh, and subcooling Tlsh respectively; where Tsh = Ts - Tdef, Tdsh = Td - To, and Tlsh = To - Tip. In this embodiment, the PID controller calculates the intake superheat Tsh, exhaust superheat Tdsh, and subcooling Tlsh respectively, providing a data basis for subsequent calculation of the temperature deviation α.

[0041] S3. Calculate the target intake superheat ΔTsh, target exhaust superheat ΔTdsh, target subcooling ΔTlsh, and target coil temperature ΔTdef respectively; where ΔTsh = a; ΔTdsh = (0.5To + 15)·(-0.003Ta + 1.008); ΔTlsh = b(0.01To + A1)·(-0.01Ta + A2); ΔTdef = c; a, b, c, A1, and A2 are all constants. In this embodiment, the target intake superheat ΔTsh, target exhaust superheat ΔTdsh, target subcooling ΔTlsh, and target coil temperature ΔTdef are calculated according to the formulas, where a, b, c, A1, and A2 are all preset empirical constants.

[0042] S4. Calculate the temperature deviation α, which includes the suction superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4; where α1 = Tsh - ΔTsh, α2 = Tdsh - ΔTdsh, α3 = Tlsh - ΔTlsh, and α4 = Tdef - ΔTdef. If the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 are all greater than zero, proceed to step S5. If the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 are all less than zero, proceed to step S6. If the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 are not all greater than zero or are all less than zero, proceed to step S7. In this embodiment, the temperature deviation α includes suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4. These four temperature deviations represent four control methods: suction superheat control, exhaust superheat control, subcooling control, and coil temperature control, respectively. The corresponding expansion valve control method is selected and executed based on the calculation result of the temperature deviation α. ​​Specifically, if the values ​​of the above four temperature deviations are all greater than zero, the next step S5 is executed; if the values ​​of the above four temperature deviations are all less than zero, the next step S6 is executed; if the values ​​of the four temperature deviations do not meet the above two conditions, the next step S7 is executed.

[0043] S5. Select the maximum value d among the intake superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4. Calculate the valve adjustment amount ΔP1 of the expansion valve based on the maximum value d, and adjust the expansion valve accordingly. In this embodiment, after calculating the temperature deviation α, if the intake superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 are all greater than zero, then select the maximum value d among these four temperature deviation values. Input this maximum value d into the PID controller. The PID controller will automatically calculate and obtain the valve adjustment amount ΔP1 based on this maximum value d, and then open the expansion valve with the valve adjustment amount ΔP1.

[0044] S6. Select the minimum value e among the intake superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4. Calculate the valve adjustment amount ΔP2 of the expansion valve based on the minimum value e, and then adjust the expansion valve to close. In this embodiment, after calculating the temperature deviation α, if the intake superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 are all less than zero, then select the minimum value e among these four temperature deviation values. Input this minimum value e into the PID controller. The PID controller will automatically calculate and obtain the valve adjustment amount ΔP2 based on this minimum value e, and then close the expansion valve with the valve adjustment amount ΔP2.

[0045] S7. Calculate the intake superheat weight β1, exhaust superheat weight β2, subcooling weight β3, and coil temperature weight β4 respectively; where β1 = 9 |ΔTsh |, β2 = 8 |ΔTdsh |, β3 = 15 |ΔTlsh |, and β4 = 10 |ΔTdef |; determine the direction of expansion valve action based on the maximum value f among intake superheat weight β1, exhaust superheat weight β2, subcooling weight β3, and coil temperature weight β4, and determine the valve adjustment amount ΔP3 of expansion valve based on the temperature deviation α. In this embodiment, after calculating the temperature deviation α, if the intake superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 do not all satisfy the condition of being greater than zero or less than zero, then the intake superheat weight β1, exhaust superheat weight β2, subcooling weight β3, and coil temperature weight β4 are calculated respectively. Then, the above four weight values ​​are compared, and the maximum value f is used to determine whether the expansion valve should open or close. The valve adjustment amount ΔP3 is determined based on the temperature deviation α, thereby controlling the expansion valve.

[0046] This expansion valve control method obtains the suction superheat Tsh, exhaust superheat Tdsh, and subcooling Tlsh, and calculates the target suction superheat ΔTsh, target exhaust superheat ΔTdsh, target subcooling ΔTlsh, and target coil temperature ΔTdef respectively, thereby obtaining the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4. Then, based on these four deviation values, the control mode of the expansion valve is selected and the specific valve adjustment is calculated. Since the suction superheat Tsh, exhaust superheat Tdsh, subcooling Tlsh, and target suction superheat Tdsh are calculated, the control method of the expansion valve is selected, and the specific valve adjustment is calculated. State parameters such as heat ΔTsh and target exhaust superheat ΔTdsh are calculated from ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, and inlet water temperature Ti. Therefore, this expansion valve control method provides a more comprehensive characterization and reflection of the working state of the heat pump unit. It can provide four control modes: suction superheat control, exhaust superheat control, subcooling control, and coil temperature control. It can fully adjust in real time according to the working conditions of the heat pump unit, avoiding the single control mode and lag, improving the accuracy of control and adjustment, and thus further improving the performance of the heat pump.

[0047] Further, in step S7, determining the expansion valve's operating direction based on the maximum value f among the intake superheat weight β1, exhaust superheat weight β2, subcooling weight β3, and coil temperature weight β4, and determining the expansion valve's adjustment amount ΔP3 based on the temperature deviation α, includes: determining the operating temperature deviation α corresponding to the maximum value f. n Action temperature deviation α nLet α be a value among the temperature deviations. Based on the intake superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4, calculate the valve adjustment amounts ΔQ1, ΔQ2, ΔQ3, and ΔQ4 of the expansion valve, respectively. If the operating temperature deviation αn is greater than zero, select the maximum value among ΔQ1, ΔQ2, ΔQ3, and ΔQ4 as the valve adjustment amount ΔP3, and adjust the expansion valve by opening it. If the operating temperature deviation αn is less than zero, select the minimum value among ΔQ1, ΔQ2, ΔQ3, and ΔQ4 as the valve adjustment amount ΔP3, and adjust the expansion valve by closing it. If the operating temperature deviation αn is less than zero, select the minimum value among ΔQ1, ΔQ2, ΔQ3, and ΔQ4 as the valve adjustment amount ΔP3, and adjust the expansion valve by closing it. n If the deviation is zero, the expansion valve will not adjust. In this embodiment, after calculating the temperature deviation α, if the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 do not all satisfy the condition of being greater than zero or less than zero, then first calculate the suction superheat weight β1, exhaust superheat weight β2, subcooling weight β3, and coil temperature weight β4, and then select the maximum value f. The suction superheat weight β1, exhaust superheat weight β2, subcooling weight β3, and coil temperature weight β4 correspond one-to-one with the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4, and select the temperature deviation α corresponding to the maximum value f as the operating temperature deviation α. n .

[0048] Regarding the specific implementation process of step S7, the following explanation uses the intake superheat weight β1 as an example: If the intake superheat weight β1 is the maximum value among the four weight values, then the intake superheat weight β1 is taken as the maximum value f, and the intake superheat deviation α1 is the operating temperature deviation α. n Then, the suction superheat deviation α1 is selected for judgment. If the suction superheat deviation α1 is greater than zero, the valve opening action is executed. At the same time, the maximum value d among the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 is selected and input into the PID controller. The PID controller will automatically calculate and obtain the valve adjustment amount ΔP3 based on the maximum value d, and then open the expansion valve with the valve adjustment amount ΔP3. If the suction superheat deviation α1 is less than zero, the valve closing action is executed. At the same time, the minimum value e among the suction superheat deviation α1, exhaust superheat deviation α2, subcooling deviation α3, and coil temperature deviation α4 is selected and input into the PID controller. The PID controller will automatically calculate and obtain the valve adjustment amount ΔP3 based on the minimum value e, and then close the expansion valve with the valve adjustment amount ΔP3. If the suction superheat deviation α1 is equal to zero, the expansion valve does not move.

[0049] Furthermore, the PID controller is used to calculate the valve adjustment quantities ΔP1, ΔP2, and ΔP3. Specifically, the PID controller consists of a proportional unit, an integral unit, and a derivative unit, and is a commonly used automation control device in the industrial control field. Its specific control logic and working principle will not be elaborated here. The PID controller can obtain ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, inlet water temperature Ti, liquid pipe temperature Tip, and coil temperature Tdef through temperature sensors. Then, it calculates the temperature deviation α, and calculates the valve adjustment quantities under four control modes: intake superheat control, exhaust superheat control, subcooling control, and coil temperature control, respectively, based on the temperature deviation α. ​​Using the PID controller, the calculation is accurate and the control is sensitive, which can better realize the real-time control of the expansion valve.

[0050] This embodiment also provides a heat pump device that uses the above-mentioned expansion valve control method to optimize the control of the expansion valve and make real-time adjustments based on the working conditions of the heat pump device. This avoids the limitations and lag of the control method, improves the accuracy of control and adjustment, and further enhances the overall performance of the heat pump device.

[0051] Furthermore, the heat pump unit includes an ambient temperature sensor, an exhaust temperature sensor, a return gas temperature sensor, an outlet water temperature sensor, an inlet water temperature sensor, a liquid line temperature sensor, a coil temperature sensor, and a PID controller. The ambient temperature sensor is used to monitor the temperature of the external environment of the heat pump unit; the exhaust temperature sensor is located at the exhaust port of the compressor; the return gas temperature sensor is located at the inlet port of the compressor; the outlet water temperature sensor is located at the outlet of the condenser; the inlet water temperature sensor is located at the return water port of the condenser; the liquid line temperature sensor is located on the connecting pipe between the condenser and the expansion valve; the coil temperature sensor is located on the connecting pipe between the expansion valve and the evaporator; the PID controller is connected to the ambient temperature sensor, the exhaust temperature sensor, the return gas temperature sensor, the outlet water temperature sensor, the inlet water temperature sensor, the liquid line temperature sensor, and the coil temperature sensor, respectively, and the PID controller is also connected to the expansion valve. In this embodiment, an ambient temperature sensor is used to measure the ambient temperature Ta around the heat pump device, an exhaust temperature sensor is used to measure the exhaust temperature Td, a return gas temperature sensor is used to measure the return gas temperature Ts, an outlet water temperature sensor is used to measure the outlet water temperature To, an inlet water temperature sensor is used to measure the inlet water temperature Ti, a liquid pipe temperature sensor is used to measure the liquid pipe temperature Tip, and a coil temperature sensor is used to measure the coil temperature Tdef. All of these temperature sensors are connected to the input terminal of a PID controller, and the output terminal of the PID controller is connected to an expansion valve, thereby enabling the adjustment of the expansion valve. The quantity is controlled; in addition, the heat pump device also includes a processing unit, which is connected to the PID controller and the expansion valve. The processing unit can determine whether the temperature deviation α, including the suction superheat deviation α1, the exhaust superheat deviation α2, the subcooling deviation α3, and the coil temperature deviation α4, is greater than zero or less than zero. It can also compare the magnitudes of the suction superheat weight β1, the exhaust superheat weight β2, the subcooling weight β3, and the coil temperature weight β4 to determine the direction of the expansion valve's action (i.e., whether to close or open the valve), thereby cooperating with the PID controller to adjust the expansion valve.

[0052] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method of controlling an expansion valve, characterized by, The method comprises the following steps: S1, acquiring the ambient temperature Ta, the exhaust temperature Td, the return air temperature Ts, the outlet water temperature To, the inlet water temperature Ti, the liquid pipe temperature Tlip and the coil temperature Tdef every preset time interval; S2, calculating the suction gas superheat Tsh, the exhaust gas superheat Tdsh and the subcooling Tlsh respectively; wherein Tsh = Ts-Tdef, Tdsh = Td-To, Tlsh = To-Tlip; S3, calculating the target suction gas superheat ΔTsh, the target exhaust gas superheat ΔTdsh, the target subcooling ΔTlsh and the target coil temperature ΔTdef respectively; wherein ΔTsh = a; ΔTdsh = (0.5To+15)·(-0.003Ta+1.008); ΔTlsh = b(0.01To+A1)·(-0.01Ta+A2); ΔTdef = c; a, b, c, A1 and A2 are all constants; S4, calculating the temperature deviation α, which comprises the suction gas superheat deviation α1, the exhaust gas superheat deviation α2, the subcooling deviation α3 and the coil temperature deviation α4; wherein α1 = Tsh-ΔTsh, α2 = Tdsh-ΔTdsh, α3 = Tlsh-ΔTlsh, α4 = Tdef-ΔTdef; if the suction gas superheat deviation α1, the exhaust gas superheat deviation α2, the subcooling deviation α3 and the coil temperature deviation α4 are all greater than zero, then executing step S5; if the suction gas superheat deviation α1, the exhaust gas superheat deviation α2, the subcooling deviation α3 and the coil temperature deviation α4 are all less than zero, then executing step S6; if the suction gas superheat deviation α1, the exhaust gas superheat deviation α2, the subcooling deviation α3 and the coil temperature deviation α4 are not all greater than zero or all less than zero, then executing step S7; S5, selecting the maximum value d from the suction gas superheat deviation α1, the exhaust gas superheat deviation α2, the subcooling deviation α3 and the coil temperature deviation α4, and calculating the valve adjustment amount ΔP1 of the expansion valve according to the maximum value d, and performing open valve adjustment on the expansion valve; S6, selecting the minimum value e from the suction gas superheat deviation α1, the exhaust gas superheat deviation α2, the subcooling deviation α3 and the coil temperature deviation α4, and calculating the valve adjustment amount ΔP2 of the expansion valve according to the minimum value e, and performing close valve adjustment on the expansion valve; S7, calculating the suction gas superheat weight β1, the exhaust gas superheat weight β2, the subcooling weight β3 and the coil temperature weight β4 respectively; wherein β1 = 9|ΔTsh|, β2 = 8|ΔTdsh|, β3 = 15|ΔTlsh|, β4 = 10|ΔTdef|; determining the action direction of the expansion valve according to the maximum value f from the suction gas superheat weight β1, the exhaust gas superheat weight β2, the subcooling weight β3 and the coil temperature weight β4, and determining the valve adjustment amount ΔP3 of the expansion valve according to the temperature deviation α. ​ 2. The expansion valve control method according to claim 1, characterized by, In step S7, the maximum value f of the suction gas superheat degree weight β1, the exhaust gas superheat degree weight β2, the subcooling degree weight β3, and the coil temperature weight β4 is determined, and the temperature deviation α is used to determine the operation direction of the expansion valve and the valve adjustment amount ΔP3 of the expansion valve. determining an operating temperature deviation a corresponding to the maximum value f n , the operating temperature deviation a n is a certain value among the temperature deviations a; The suction gas superheat degree deviation α1, the exhaust gas superheat degree deviation α2, the subcooling degree deviation α3, and the coil temperature deviation α4 are used to calculate the valve adjustment amount ΔQ1, the valve adjustment amount ΔQ2, the valve adjustment amount ΔQ3, and the valve adjustment amount ΔQ4 of the expansion valve, respectively. If the action temperature deviation a n If the action temperature deviation a If the action temperature deviation a If the action temperature deviation a n If the action temperature deviation a If the action temperature deviation a If the action temperature deviation a n is equal to zero, the expansion valve is not regulated.

3. The expansion valve control method according to any one of claims 1-2, characterized by, The PID controller is used to calculate the valve adjustment amount ΔP1, the valve adjustment amount ΔP2, and the valve adjustment amount ΔP3.

4. Heat pump apparatus, characterised in that The expansion valve control method of any one of claims 1-3 is used for control.

5. Heat pump apparatus according to claim 4, characterised in that The heat pump device comprises an ambient temperature sensor, an exhaust gas temperature sensor, a return gas temperature sensor, an outlet water temperature sensor, an inlet water temperature sensor, a liquid pipe temperature sensor, a coil temperature sensor, and a PID controller. The ambient temperature sensor is used to monitor the temperature of the external environment of the heat pump device; the exhaust gas temperature sensor is arranged at the exhaust port of the compressor; the return gas temperature sensor is arranged at the inlet of the compressor; the outlet water temperature sensor is arranged at the outlet of the condenser; the inlet water temperature sensor is arranged at the return port of the condenser; the liquid pipe temperature sensor is arranged on the connecting pipe between the condenser and the expansion valve; and the coil temperature sensor is arranged on the connecting pipe between the expansion valve and the evaporator. The PID controller is connected with the ambient temperature sensor, the exhaust gas temperature sensor, the return gas temperature sensor, the outlet water temperature sensor, the inlet water temperature sensor, the liquid pipe temperature sensor, and the coil temperature sensor, respectively, and is also connected with the expansion valve.

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