Control method of air source heat pump unit

Abstract

The invention relates to the technical field of air source heat pump units, particularly provides a control method of an air source heat pump unit, and aims to solve the problem of how to improve the condensing temperature of the air source heat pump unit under the condition of using a fixed-frequency fan. In order to achieve the purpose, the control method of the air source heat pump unit comprises the steps that the outdoor environment temperature and the exhaust pressure saturation temperature are obtained, the outdoor environment temperature is compared with a first environment temperature threshold value, the exhaust pressure saturation temperature is compared with a first exhaust pressure saturation temperature threshold value, and then the air source heat pump unit is controlled on the basis of comparison results. Opening and closing of the two throttle valves are selectively controlled. According to the arrangement mode, the two throttling valves are arranged, the heat exchange amount of the first heat exchanger can be adjusted and reduced according to the operation working condition, the condensation temperature can be increased under the condition that the air source heat pump unit uses the fixed-frequency draught fan, and then the heat exchange effect of the air source heat pump unit is improved; and the air source heat pump unit has good refrigerating capacity under the low-temperature working condition.

Description

Technical Field

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

[0001] When the air source heat pump unit operates under the refrigeration condition, when the ambient temperature decreases, the heat exchange temperature difference between the heat exchanger in the air source heat pump unit and the air increases, resulting in a significant decrease in the condensation temperature of the air source heat pump unit. Especially when the condensation temperature of the air source heat pump unit is lower than the condensation temperature limit value of the compressor, it may cause damage to the compressor or shorten its operating life.

[0002] At present, the fixed-frequency fan cannot effectively reduce the condensation temperature of the air source heat pump unit. Although the variable-frequency fan solution can reduce the heat exchange effect between the heat exchanger and the air by reducing the fan speed and increase the condensation temperature of the air source heat pump unit, this solution has a high cost, complex control, and the heat exchange effect is not ideal in low-temperature environments.

[0003] Therefore, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0004] In order to solve at least one problem in the prior art, that is, to solve the problem of how to increase the condensation temperature of the air source heat pump unit when using a fixed-frequency fan, the present application provides a control method for an air source heat pump unit. The air source heat pump unit includes a compressor, a first heat exchanger, a flow splitting component, and a second heat exchanger that are sequentially connected to form a loop. Among them, the first heat exchanger includes two heat exchange pipe sections, the flow splitting component includes two throttle valves arranged in parallel and corresponding to the heat exchange pipe sections one by one, and the first end of the throttle valve is connected to the outlet side of the corresponding heat exchange pipe section, and the second ends are all connected to the inlet side of the second heat exchanger. The control method of the air source heat pump unit includes:

[0005] Obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt at the outlet side of the compressor;

[0006] Compare the magnitude of the outdoor ambient temperature Tao with the first ambient temperature threshold Ta1 and the magnitude of the exhaust pressure saturation temperature Pdt with the first exhaust pressure saturation temperature threshold P1;

[0007] Based on the comparison result, selectively control the opening and closing of the two throttle valves.

[0008] In a preferred technical solution of the above control method for an air source heat pump unit, the step of "based on the comparison result, selectively control the opening and closing of the two throttle valves" further includes:

[0009] When Tao < Ta1 and / or Pdt < P1, control one of the throttle valves to open.

[0010] In a preferred technical solution of the above control method for an air source heat pump unit, after the step of "control one of the throttle valves to open", the following steps are further included:

[0011] Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt;

[0012] Compare the magnitude of the outdoor ambient temperature Tao with a second ambient temperature threshold Ta2 and the magnitude of the exhaust pressure saturation temperature Pdt with a second exhaust pressure saturation temperature threshold P2;

[0013] Based on the comparison result, selectively control the other throttle valve to open.

[0014] In a preferred technical solution of the above control method for an air source heat pump unit, the step of "based on the comparison result, selectively control the opening and closing of the other throttle valve" further includes:

[0015] When Tao > Ta2 and Pdt ≥ P2, control the other throttle valve to open, otherwise maintain the opening and closing states of the two throttle valves, and cycle in this way until Tao < Ta1 and / or Pdt < P1.

[0016] In a preferred technical solution of the above control method for an air source heat pump unit, the step of "based on the comparison result, selectively control the opening and closing of the two throttle valves" further includes:

[0017] When Tao ≥ Ta1 and Pdt ≥ P1, control the two throttle valves to open.

[0018] In a preferred technical solution of the above control method for an air source heat pump unit, after the step of "control the two throttle valves to open", the following steps are further included:

[0019] Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt;

[0020] Compare the magnitude of the outdoor ambient temperature Tao with a first ambient temperature threshold Ta1 and the magnitude of the exhaust pressure saturation temperature Pdt with a first exhaust pressure saturation temperature threshold P1;

[0021] When Tao < Ta1 and / or Pdt < P1, control one of the throttle valves to close, otherwise maintain the opening and closing states of the two throttle valves, and cycle in this way until Tao > Ta2 and Pdt ≥ P2.

[0022] In the preferred technical solution of the control method of the above air source heat pump unit, after the step of "controlling one of the throttle valves to close", the method further includes:

[0023] Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt;

[0024] Compare the magnitude of the outdoor ambient temperature Tao with the second ambient temperature threshold Ta2 and the magnitude of the exhaust pressure saturation temperature Pdt with the second exhaust pressure saturation temperature threshold P2;

[0025] When Tao > Ta2 and Pdt ≥ P2, control the opening of the two throttle valves, otherwise maintain the opening and closing states of the two throttle valves, and cycle in this way until Tao < Ta1 and / or Pdt < P1.

[0026] In the preferred technical solution of the control method of the above air source heat pump unit, after "selectively controlling the opening and closing of the two throttle valves", the control method further includes:

[0027] After the throttle valve in the open state operates for a second set time, control the throttle valve to enter the automatic control mode.

[0028] In the preferred technical solution of the control method of the above air source heat pump unit, the step of "controlling the throttle valve to enter the automatic control mode" further includes:

[0029] Obtain the suction temperature T1 and the suction pressure saturation temperature T2 of the compressor;

[0030] Based on the suction temperature T1 and the suction pressure saturation temperature T2, determine the opening adjustment amount Δeev of the throttle valve;

[0031] Based on the opening adjustment amount Δeev, adjust the opening of the throttle valve;

[0032] Cycle in this way according to the third set time until the opening and closing state of any one of the throttle valves changes.

[0033] In the preferred technical solution of the control method of the above air source heat pump unit, the step of "adjusting the opening of the throttle valve based on the opening adjustment amount" specifically includes: calculating the suction superheat SH based on the suction temperature T1 and the suction pressure saturation temperature T2;

[0034] Among them, the calculation formula of the suction superheat SH is:

[0035] SH = T1 - T2;

[0036] Based on the suction superheat SH, determine the target value sh;

[0037] Based on the suction superheat SH and the target value sh, calculate the deviation value ΔSH and the change rate ΔSH'.

[0038] Among them, the calculation formula for the deviation value ΔSH is:[[]]

[0039] ΔSH = SH' - sh;

[0040] The calculation formula for the change rate ΔSH' is:[[]]

[0041] ΔSH' = SH' - SH' t-1 ;

[0042] Based on the deviation value ΔSH and the change rate ΔSH', calculate the opening adjustment amount Δeev.[[]]

[0043] Among them, the calculation formula for the opening adjustment amount Δeev is:[[]]

[0044] Δeev = a1×ΔSH + b1×ΔSH';

[0045] Among them, SH' is the suction superheat at the current moment; SH' t-1 is the suction superheat at the previous moment; a1 and b1 are the coefficients of the fitting formula.[[]]

[0046] Those skilled in the art can understand that for the control method of the air source heat pump unit of the present application, when the air source heat pump unit is started, the outdoor ambient temperature and the exhaust pressure saturation temperature on the outlet side of the compressor are obtained, and the magnitudes of the outdoor ambient temperature and the first ambient temperature threshold and the magnitudes of the exhaust pressure saturation temperature and the first exhaust pressure saturation temperature threshold are compared. Then, based on the comparison results, the opening and closing of the two throttle valves are selectively controlled. In the above setting method, the two throttle valves can adjust the heat exchange amount of the first heat exchanger according to the operating conditions, so that the air source heat pump unit can increase the condensation temperature of the air source heat pump unit when using a constant frequency fan, thereby improving the heat exchange effect of the air source heat pump unit and enabling the air source heat pump unit to have good refrigeration capacity under low temperature conditions.[[]]

[0047] Furthermore, by controlling one throttle valve to open when the outdoor ambient temperature is less than the first ambient temperature threshold or the exhaust pressure saturation temperature is less than the first exhaust pressure saturation temperature threshold, the heat exchange amount of the first heat exchanger can be reduced, the condensation temperature of the air source heat pump unit can be increased, and the air source heat pump unit can have good refrigeration capacity under low temperature conditions.[[]]

[0048] Furthermore, after controlling a throttle valve to open, continue to obtain the outdoor ambient temperature and the saturated temperature of the exhaust pressure on the outlet side of the compressor, and compare the outdoor ambient temperature with the second ambient temperature threshold and the saturated temperature of the exhaust pressure with the second exhaust pressure saturated temperature threshold. When the outdoor ambient temperature is greater than the second ambient temperature threshold and the saturated temperature of the exhaust pressure is greater than or equal to the second exhaust pressure saturated temperature threshold, controlling two throttle valves to open can improve the heat exchange efficiency of the air source heat pump unit.

[0049] Furthermore, by controlling two throttle valves to open when the outdoor ambient temperature is greater than or equal to the first ambient temperature threshold and the saturated temperature of the exhaust pressure is greater than or equal to the first exhaust pressure saturated temperature threshold, the heat exchange efficiency of the air source heat pump unit can be improved.

[0050] Furthermore, after controlling one throttle valve to open, continue to obtain the outdoor ambient temperature and the saturated temperature of the exhaust pressure on the outlet side of the compressor, and compare the outdoor ambient temperature with the first ambient temperature threshold and the saturated temperature of the exhaust pressure with the first exhaust pressure saturated temperature threshold. When the outdoor ambient temperature is less than the first ambient temperature threshold and the saturated temperature of the exhaust pressure is less than or equal to the second exhaust pressure saturated temperature threshold, controlling one throttle valve to open can improve the heat exchange efficiency of the air source heat pump unit, reduce the heat exchange amount of the first heat exchanger, increase the condensation temperature of the air source heat pump unit, and enable the air source heat pump unit to have good refrigeration capacity under low temperature conditions.

[0051] Furthermore, after controlling a throttle valve to open, continue to obtain the outdoor ambient temperature and the saturated temperature of the exhaust pressure on the outlet side of the compressor, and compare the outdoor ambient temperature with the second ambient temperature threshold and the saturated temperature of the exhaust pressure with the second exhaust pressure saturated temperature threshold. When the outdoor ambient temperature is greater than the second ambient temperature threshold and the saturated temperature of the exhaust pressure is greater than or equal to the second exhaust pressure saturated temperature threshold, controlling two throttle valves to open can improve the heat exchange efficiency of the air source heat pump unit.

[0052] Furthermore, after selectively controlling the opening and closing of two throttle valves, control the throttle valve in the open state to enter the automatic control mode, so as to be able to adjust the throttle valve according to the actual situation and avoid energy waste. Brief Description of the Drawings

[0053] The following describes the preferred embodiments of the present invention in conjunction with the drawings, in which:

[0054] Figure 1 is a schematic diagram of the system of the air source heat pump unit of the present application;

[0055] Figure 2It is a flowchart of the control method of the air source heat pump unit of the present application;

[0056] Figure 3 It is a logic diagram of a possible implementation manner of the control method of the air source heat pump unit of the present application;

[0057] Figure 4 It is a logic diagram of a possible implementation manner of the throttle valve of the present application in the automatic control mode.

[0058] List of reference numerals:

[0059] 1. Compressor; 2. Four-way valve; 3. Finned heat exchanger; 4. Diverting assembly; 41. Liquid distributor; 42. Second filter; 43. Throttle valve; 5. First filter; 6. Water-side heat exchanger; 7. Gas-liquid separator. Detailed implementation manners

[0060] The preferred implementation manners of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principle of the present application and are not intended to limit the protection scope of the present application.

[0061] It should be noted that in the description of the present application, the terms indicating the direction or positional relationship such as "upper", "lower", "inner", "bottom", "end" are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0062] In addition, it should be noted that in the description of the present application, unless otherwise clearly specified and limited, the terms "set", "connected", "communicated" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0063] First, refer to Figure 1 , and introduce the air source heat pump unit of the present application.

[0064] As Figure 1As shown, to solve the problem of how to increase the condensation temperature of an air source heat pump unit when using a fixed-frequency fan, the air source heat pump unit of the present application includes a compressor 1, a first heat exchanger, a flow splitting assembly 4, and a second heat exchanger that are connected in sequence to form a loop; among them, the first heat exchanger includes two heat exchange pipe sections, the flow splitting assembly 4 includes two throttle valves 43 arranged in parallel and corresponding to the heat exchange pipe sections one by one, and the first end of the throttle valve 43 is connected to the outlet side of the corresponding heat exchange pipe section, and the second ends are all connected to the inlet side of the second heat exchanger.

[0065] In the present application, two throttle valves 43 are arranged in parallel on the outlet side of the first heat exchanger, so that these two throttle valves 43 can adjust and change the heat exchange amount of the first heat exchanger according to the operating conditions, increase the condensation temperature of the air source heat pump unit, and enable the air source heat pump unit to have good refrigeration capacity under low-temperature conditions. This structure enables the air source heat pump unit to adjust the heat exchange amount more flexibly according to actual needs, improve the energy utilization efficiency, and at the same time protect the air source heat pump unit and extend its service life.

[0066] Next, referring to Figure 1 , the first heat exchanger is a finned heat exchanger 3, and the second heat exchanger is a water-side heat exchanger 6. The air source heat pump unit further includes a four-way valve 2, a gas-liquid separator 7, and a first filter 5. The flow splitting assembly 4 further includes two distributors 41 and two second filters 42. Among them, a first filter 5 is provided on the inlet side of the second heat exchanger, the a end of the four-way valve 2 is connected to the outlet side of the compressor 1, the b end of the four-way valve 2 is connected to the inlet side of the first heat exchanger, the c end of the four-way valve 2 is connected to the outlet side of the second heat exchanger, and the d end of the four-way valve 2 is connected to the inlet side of the compressor 1. The heat exchange pipe section is connected to the first end of the throttle valve 43 through a distributor 41, and the second end of the throttle valve 43 is connected to the first filter 5 through a second filter 42.

[0067] Of course, the types of settings of the first heat exchanger and the second heat exchanger in the present application are not fixed, and those skilled in the art can adjust them according to needs. For example, the first heat exchanger can be a water-side heat exchanger 6, and the second heat exchanger can be a finned heat exchanger 3. Or, both the first heat exchanger and the second heat exchanger are water-side heat exchangers 6 or finned heat exchangers 3. Or, the first heat exchanger and the second heat exchanger can also be other types of heat exchangers, as long as the opening and closing of the two throttle valves 43 can adjust and change the heat exchange amount of the first heat exchanger.

[0068] In addition, the number of liquid distributors 41 provided in this application is not fixed, and those skilled in the art can adjust it according to specific application scenarios. For example, there can be one liquid distributor 41, that is, one liquid distributor 41 is provided on the outlet side of the first heat exchanger, and this liquid distributor 41 is respectively connected to two second filters 42. In other preferred embodiments, the provision of the liquid distributor 41 and / or the second filter 42 is not necessary, and those skilled in the art can select according to needs. With both throttle valves 43 in the open state, combined with Figure 1 The working principle of the air source heat pump unit of this application will be described. When both throttle valves 43 are in the open state, the high-temperature refrigerant gas discharged from the compressor 1 passes through the four-way valve 2, enters the fin heat exchanger 3 to release heat, condenses into a refrigerant liquid, then passes through two liquid distributors 41 respectively, and then enters the corresponding first filter 5 and throttle valve 43, and then converges and enters the second filter 42. After absorbing heat through the water-side heat exchanger 6, the refrigerant absorbs heat and evaporates. The gaseous refrigerant passes through the four-way valve 2 and the gas-liquid separator 7 and enters the compressor 1 to be compressed again.

[0069] With one throttle valve 43 in the open state, combined with Figure 1 The working principle of the air source heat pump unit of this application will be described. When one throttle valve 43 is in the open state and the other throttle valve 43 is in the closed state, the high-temperature refrigerant gas discharged from the compressor 1 passes through the four-way valve 2, enters the fin heat exchanger 3 to release heat, condenses into a refrigerant liquid, and then sequentially passes through the liquid distributor 41 and the first filter 5 corresponding to the open throttle valve 43, then enters the throttle valve 43, and then enters the water-side heat exchanger 6 to absorb heat. The refrigerant absorbs heat and evaporates. The gaseous refrigerant passes through the four-way valve 2 and the gas-liquid separator 7 and enters the compressor 1 to be compressed again.

[0070] Referring to Figure 2 , the control method of the air source heat pump unit of this application will be described. Among them, Figure 2 is the flow chart of the control method of the air source heat pump unit of this application.

[0071] As Figure 2 shown, the control method of the air source heat pump unit of this application includes:

[0072] S101. Obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt on the outlet side of the compressor 1; for example, the air source heat pump unit can be configured with components for obtaining temperature, and the outdoor ambient temperature and the exhaust pressure saturation temperature can be detected through these components.

[0073] S102. Compare the magnitudes of the outdoor ambient temperature Tao and the first ambient temperature threshold Ta1, as well as the magnitudes of the exhaust pressure saturation temperature Pdt and the first exhaust pressure saturation temperature threshold P1. For example, after detecting the outdoor ambient temperature Tao, compare their magnitudes by checking whether the difference between the outdoor ambient temperature Tao and the first ambient temperature threshold Ta1 is greater than 0, or whether the ratio between the two is greater than 1. After detecting the exhaust pressure saturation temperature Pdt, compare their magnitudes by checking whether the difference between the exhaust pressure saturation temperature Pdt and the first exhaust pressure saturation temperature threshold P1 is greater than 0, or whether the ratio between the two is greater than 1.

[0074] S103. Based on the comparison results, selectively control the opening and closing of the two throttle valves 43. For example, when the outdoor ambient temperature Tao is less than the first ambient temperature threshold Ta1 and the exhaust pressure saturation temperature Pdt is less than the first exhaust pressure saturation temperature threshold P1, control one throttle valve 43 to open. When the outdoor ambient temperature Tao is greater than the first ambient temperature threshold Ta1 and the exhaust pressure saturation temperature Pdt is greater than the first exhaust pressure saturation temperature threshold P1, control the two throttle valves 43 to open.

[0075] The preferred embodiments of the control method for the air source heat pump unit of the present application are introduced below.

[0076] In one embodiment, the step of "selectively controlling the opening and closing of the two throttle valves 43 based on the comparison results" further includes:

[0077] When Tao < Ta1 and / or Pdt < P1, control one throttle valve 43 to open.

[0078] For example, taking Ta1 = 10°C and P1 = 90°C as an example. When Tao < 10°C, it indicates that the outdoor ambient temperature is relatively low. When Pdt < 90°C, it indicates that the air compression ratio of the compressor 1 is low and the refrigeration capacity of the air source heat pump unit is low. Therefore, when Tao < 10°C and / or Pdt < 90°C, in order to increase the condensation temperature of the air source heat pump unit, control one throttle valve 43 to open, so as to reduce the heat exchange capacity of the fin heat exchanger 3, and further reduce the heat transfer amount of the fin heat exchanger 3, thereby effectively increasing the condensation temperature of the air source heat pump unit and further improving the refrigeration capacity of the air source heat pump unit.

[0079] It should be noted that the air source heat pump unit of the present application includes two throttle valves 43. When controlling one throttle valve 43 to open, this throttle valve 43 can be any one of the two throttle valves 43, and there is no limitation here.

[0080] Furthermore, after the step of "controlling one throttle valve 43 to open", it further includes:

[0081] Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt;

[0082] Compare the magnitude of the outdoor ambient temperature Tao with the second ambient temperature threshold Ta2 and the magnitude of the exhaust pressure saturation temperature Pdt with the second exhaust pressure saturation temperature threshold P2;

[0083] Based on the comparison result, selectively control the opening of the other throttle valve 43.

[0084] Specifically, the step of "based on the comparison result, selectively control the opening of the other throttle valve 43" further includes: when Tao > Ta2 and Pdt ≥ P2, control the opening of the other throttle valve 43, otherwise control the opening and closing states of the two throttle valves 43, and cycle in this way until Tao < Ta1 and / or Pdt < P1.

[0085] For example, take the first set time as 5 min, Ta1 = 10 °C, P1 = 90 °C, Ta2 = 20 °C, and P2 = 100 °C as an example for illustration. When Tao < 10 °C and / or Pdt < 90 °C, after controlling one throttle valve 43 to open, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt every 5 min, and compare the magnitude of the outdoor ambient temperature Tao with the second ambient temperature threshold Ta2 and the magnitude of the exhaust pressure saturation temperature Pdt with the second exhaust pressure saturation temperature threshold P2. When Tao ≤ 20 °C and / or Pdt < 100 °C, it indicates that the outdoor ambient temperature is relatively low and the air compression ratio of the compressor 1 is relatively low. At this time, it is necessary to continue to keep one throttle valve 43 in the open state. When Tao > 20 °C and Pdt ≥ 100 °C, it indicates that the outdoor ambient temperature and the air compression ratio of the compressor 1 are relatively high. At this time, control the opening of the other throttle valve 43, that is, both throttle valves 43 are in the open state, which can improve the heat exchange efficiency of the fin heat exchanger 3. Cycle in this way to obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt every 5 min, and keep both throttle valves 43 in the open state until Tao < Ta1 and / or Pdt < P1.

[0086] In one embodiment, the step of "based on the comparison result, selectively control the opening and closing of the two throttle valves 43" further includes:

[0087] When Tao ≥ Ta1 and Pdt ≥ P1, control the two throttle valves 43 to open.

[0088] For example, taking Ta1 = 10°C and P1 = 90°C as an example for illustration. When Tao ≥ 10°C and Pdt ≥ 90°C, it indicates that the outdoor ambient temperature and the air compression of the compressor 1 are relatively high. At this time, controlling the two throttle valves 43 to open can improve the heat exchange efficiency of the air source heat pump unit.

[0089] Further, after the step of "controlling the two throttle valves 43 to open", the following steps are also included:

[0090] Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt;

[0091] Compare the magnitude of the outdoor ambient temperature Tao with the first ambient temperature threshold Ta1 and the magnitude of the exhaust pressure saturation temperature Pdt with the first exhaust pressure saturation temperature threshold P1;

[0092] When Tao < Ta1 and / or Pdt < P1, control one throttle valve 43 to close, otherwise maintain the opening and closing states of the two throttle valves 43, and cycle in this way until Tao > Ta2 and Pdt ≥ P2.

[0093] For example, taking the first set time as 5 minutes, Ta1 = 10°C, P1 = 90°C, Ta2 = 20°C, and P2 = 100°C as an example for illustration. When Tao ≥ 10°C and Pdt ≥ 90°C, after controlling the two throttle valves 43 to open, continue to obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt every 5 minutes, and compare the magnitude of the outdoor ambient temperature Tao with the first ambient temperature threshold Ta1 and the magnitude of the exhaust pressure saturation temperature Pdt with the first exhaust pressure saturation temperature threshold P1. When Tao < 10°C and / or Pdt < 90°C, it indicates that the outdoor ambient temperature decreases and / or the air compression ratio of the compressor 1 decreases. At this time, change the opening state of the two throttle valves 43 and control one throttle valve 43 to close, that is, only maintain the opening state of one throttle valve 43. Cycle in this way to obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt every 5 minutes and maintain the opening state of one throttle valve 43 until Tao > 20°C and Pdt ≥ 100°C.

[0094] It should be noted that there are two throttle valves 43 in the air source heat pump unit of the present application. When controlling one throttle valve 43 to close, this throttle valve 43 can be any one of the two throttle valves 43, and there is no limitation here.

[0095] Even further, after the step of "controlling one throttle valve 43 to open", the following steps are also included:

[0096] Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt;

[0097] Compare the magnitude of the outdoor ambient temperature Tao and the second ambient temperature threshold Ta2, as well as the magnitude of the exhaust pressure saturation temperature Pdt and the second exhaust pressure saturation temperature threshold P2;

[0098] When Tao > Ta2 and Pdt ≥ P2, control the opening of the two throttle valves 43, otherwise maintain the opening and closing states of the two throttle valves 43, and cycle in this way until Tao < Ta1 and / or Pdt < P1.

[0099] For example, taking the first set time as 5 min, Ta1 = 10 °C, P1 = 90 °C, Ta2 = 20 °C, and P2 = 100 °C as an example for illustration. When Tao < 10 °C and / or Pdt < 90 °C, after controlling one throttle valve 43 to open, continue to obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt every 5 min, and compare the magnitude of the outdoor ambient temperature Tao and the second ambient temperature threshold Ta2, as well as the magnitude of the exhaust pressure saturation temperature Pdt and the second exhaust pressure saturation temperature threshold P2. When Tao ≤ 20 °C and / or Pdt < 100 °C, it indicates that the outdoor ambient temperature is relatively low and / or the air compression of the compressor 1 is relatively low. At this time, it is necessary to continue to maintain the open state of one throttle valve 43. When Tao > 20 °C and Pdt ≥ 100 °C, it indicates that the outdoor ambient temperature and the air compression of the compressor 1 are relatively high, and the refrigeration capacity of the air source heat pump unit is high. At this time, controlling the opening of the two throttle valves 43 can improve the heat exchange efficiency of the fin heat exchanger 3. Cycle in this way to obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt every 5 min, and maintain the open state of the two throttle valves 43 until Tao < 10 °C and / or Pdt < 90 °C.

[0100] In one embodiment, after "selectively controlling the opening and closing of the two throttle valves 43", it further includes:

[0101] After controlling the throttle valve 43 in the open state to operate for the second set time, control this throttle valve 43 to enter the automatic control mode.

[0102] It should be noted that by controlling the throttle valve 43 in the open state to enter the automatic control mode, it is convenient to adjust the opening adjustment amount of the throttle valve 43 so as to be able to adjust the opening of the throttle valve 43 according to the actual situation. The application has no limitation on the second set time, as long as the throttle valve 43 can enter the automatic control mode. For example, the second set time can be 0 s, 1 s, 5 s, 10 s, etc.

[0103] It should also be noted that since the present application needs to enter the automatic control mode after selectively controlling the opening of the two throttle valves 43 and adjust their opening degrees. Therefore, there is no limit to the original opening degree of the throttle valve 43. For example, the throttle valve 43 can be controlled to open to the maximum opening degree, or the throttle valve 43 can be opened to 50% of the maximum opening degree, etc.

[0104] Further, the step of "controlling the throttle valve 43 to enter the automatic control mode" further includes:

[0105] obtaining the suction temperature T1 of the compressor 1 and the suction pressure saturation temperature T2;

[0106] determining the opening degree adjustment amount of the throttle valve 43 based on the suction temperature T1 and the suction pressure saturation temperature T2;

[0107] adjusting the opening degree of the throttle valve 43 based on the opening degree adjustment amount;

[0108] circulating in this way according to the third set time until the opening and closing state of any throttle valve 43 changes.

[0109] According to the suction temperature and the suction pressure saturation temperature, the gas volume in the compressor 1 can be judged, thereby determining the refrigeration capacity of the compressor 1. By monitoring these two parameters, the opening degree range of the throttle valve 43 can be controlled to realize the real-time adjustment of the refrigeration capacity of the compressor 1. By circulating the above operations and timely adjusting the opening degree of the throttle valve 43, the normal operation of the compressor 1 can be ensured and the best refrigeration effect can be achieved.

[0110] It should be noted that there is no limit to the third set time in the present application, as long as the opening degree adjustment amount of the throttle valve 43 can be adjusted in time according to the suction temperature and the suction pressure saturation temperature. For example, the third set time can be 30s.

[0111] Specifically, the opening degree adjustment amount of the throttle valve 43 can be obtained according to the following steps:

[0112] calculating the suction superheat SH based on the suction temperature T1 of the compressor 1 and the suction pressure saturation temperature T2 of the compressor 1;

[0113] determining the target value sh based on the outdoor ambient temperature Tao;

[0114] calculating the deviation value ΔSH and the change rate ΔSH' based on the suction superheat SH' and the target value sh;

[0115] calculating the opening degree adjustment amount Δeev of the throttle valve 43 based on the deviation value ΔSH and the change rate ΔSH';

[0116] wherein, the calculation formula of the suction superheat SH is: SH' = T1 - T2;

[0117] The calculation formula for the deviation value ΔSH is: ΔSH = SH’ - sh;

[0118] The calculation formula for the change rate ΔSH’ is: ΔSH’ = SH’ - SH’ t-1 ;

[0119] The calculation formula for the opening adjustment amount Δeev is:

[0120] Δeev = a1 × ΔSH + b1 × ΔSH’;

[0121] where SH’ is the suction superheat at the current moment; SH’ t-1 is the suction superheat at the previous moment; a1 and b1 are the coefficients of the fitting formula.

[0122] It should be noted that the suction superheat SH’ at the previous moment t-1 refers to the suction superheat calculated in the previous cycle. ΔSH and ΔSH’ can be positive or negative, and correspondingly, the opening adjustment amount Δeev can also be positive or negative. When the opening adjustment amount Δeev is positive, it means that the opening of the throttle valve 43 needs to be increased. When the opening adjustment amount Δeev is negative, it means that the opening of the throttle valve 43 needs to be decreased.

[0123] In addition, the coefficients of the fitting formula can be determined with the opening unit of the throttle valve as a percentage, or can be determined according to the opening unit of the throttle valve as steps. When the opening unit of the throttle valve is a percentage, the maximum opening of the throttle valve is 100%. When the opening unit of the throttle valve is steps, the maximum opening of the throttle valve can be 480 steps.

[0124] For example, taking sh = 3℃ when Tao = 10℃, T1 = 10℃, T2 = 4℃, Tao = 10℃, SH’ = 10℃, a1 = 0.5% / ℃, b1 = 0.5% / ℃ as an example. According to the calculation formula for the suction superheat SH, SH = T1 - T2, SH’ = 6℃ can be calculated. Then, according to the calculation formula for the deviation value ΔSH, ΔSH = SH’ - sh, ΔSH = 3℃ is calculated. For the calculation formula of the change rate ΔSH’, ΔSH’ = SH’ - SH’ t-1 , ΔSH’ = -4℃ is calculated. Finally, according to Δeev = a1 × ΔSH + b1 × ΔSH’, Δeev = -2% is calculated. That is to say, the opening of the throttle valve 43 needs to be decreased, and the opening of the throttle valve 43 needs to be adjusted down by 2% of the maximum opening on the basis of the original opening.

[0125] It should be noted that when a1 and b1 are also determined according to the number of steps of the throttle valve 43, taking sh = 3°C, T1 = 10°C, T2 = 4°C, Tao = 10°C, SH' = 10°C, a1 = 5 steps / °C, and b1 = 5 steps / °C at Tao = 10°C as an example, it can be calculated that Δeev = -5 steps. That is to say, the opening of the throttle valve 43 needs to be reduced, and the opening of the throttle valve 43 is adjusted down by 5 steps.

[0126] The following combines Figure 3 to briefly describe a possible operation process of the control method of the air source heat pump unit of the present application. Figure 3 It is a logic diagram of a possible implementation manner of the control method of the air source heat pump unit of the present application.

[0127] S201. Obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt at the outlet side of the compressor 1, and then execute S202.

[0128] S202. Determine whether Tao < 10°C and / or Pdt < 90°C holds? If it holds, execute S203; if it does not hold, execute S207.

[0129] S203. Control one throttle valve 43 to open and the other throttle valve 43 to close, and then execute S204 and S213.

[0130] S204. Every 5 minutes, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt at the outlet side of the compressor 1, and then execute S205.

[0131] S205. Determine whether Tao > 20°C and Pdt ≥ 100°C holds? If it holds, execute S206; if it does not hold, execute S203.

[0132] S206. Control the other throttle valve 43 to open, and then execute S207 and S213.

[0133] S207. Control both throttle valves 43 to open, and then execute S208 and S213.

[0134] S208. Every 5 minutes, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt at the outlet side of the compressor 1, and then execute S209.

[0135] S209. Determine whether Tao < 10°C and / or Pdt < 90°C holds? If it holds, execute S210; if it does not hold, execute S207.

[0136] S210. Control one throttle valve 43 to close, and then execute S211 and S213.

[0137] S211: Every 5 minutes, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt on the outlet side of the compressor 1, and then execute S212.

[0138] S212: Determine whether Tao > 20°C and Pdt ≥ 100°C hold. If it holds, execute S207; if not, execute S210.

[0139] S213: After 10 seconds, control the throttle valve 43 in the open state to enter the automatic control mode.

[0140] In addition, in combination with Figure 4 , a possible operating process of the throttle valve 43 in the automatic control mode is briefly described. Figure 4 This is a logic diagram of a possible implementation manner of the throttle valve 43 of the present application in the automatic control mode.

[0141] S301: Obtain the suction temperature T1 and the suction pressure saturation temperature T2 of the compressor 1, and then execute S302.

[0142] S302: Based on the calculation formula of the suction superheat SH: SH = T1 - T2, calculate the suction superheat SH, and then execute S303.

[0143] S303: Based on the outdoor ambient temperature Tao, determine the target value sh, and then execute S304.

[0144] S304: Based on the calculation formula of the deviation value ΔSH: ΔSH = SH’ - sh and the calculation formula of the change rate ΔSH’: ΔSH’ = SH’ - SH’ t-1 , calculate the deviation value ΔSH and the change rate ΔSH’, and then execute S305.

[0145] S305: Based on the calculation formula of the opening adjustment amount Δeev: Δeev = a1×ΔSH + b1×ΔSH’, calculate the opening adjustment amount Δeev of the throttle valve 43, and then execute S306.

[0146] S306: Adjust the opening of the throttle valve 43 according to the opening adjustment amount Δeev, and continue to execute S301 after 30 seconds.

[0147] Those skilled in the art can understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of the present application and forms different embodiments. For example, in the claims of the present application, any one of the claimed embodiments can be used in any combination.

[0148] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easily understood by those skilled in the art that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principle of the present application, 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 all fall within the protection scope of the present application.

Claims

1. A control method for an air source heat pump unit, characterized in that, The air source heat pump unit includes a compressor, a first heat exchanger, a flow splitting component, and a second heat exchanger that are connected in sequence to form a loop; wherein, the first heat exchanger includes two heat exchange pipe segments, the flow splitting component includes two throttle valves arranged in parallel and corresponding to the heat exchange pipe segments one by one, and the first end of the throttle valve is connected to the outlet side of the corresponding heat exchange pipe segment, and the second ends are all connected to the inlet side of the second heat exchanger; The control method of the air source heat pump unit includes: Obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt on the outlet side of the compressor; Compare the magnitude of the outdoor ambient temperature Tao with the first ambient temperature threshold Ta1 and the magnitude of the exhaust pressure saturation temperature Pdt with the first exhaust pressure saturation temperature threshold P1; Based on the comparison result, selectively control the opening and closing of the two throttle valves.

2. The control method of the air source heat pump unit according to claim 1, characterized in that The step of "selectively controlling the opening and closing of the two throttle valves based on the comparison result" further includes: When Tao < Ta1, and / or Pdt < P1, control one of the throttle valves to open.

3. The control method of the air source heat pump unit according to claim 2, characterized in that, After the step of "controlling one of the throttle valves to open", it further includes: Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt; Compare the magnitude of the outdoor ambient temperature Tao with the second ambient temperature threshold Ta2 and the magnitude of the exhaust pressure saturation temperature Pdt with the second exhaust pressure saturation temperature threshold P2; Based on the comparison result, selectively control the other throttle valve to open.

4. The control method of the air source heat pump unit according to claim 3, characterized in that, The step of "selectively controlling the other throttle valve to open based on the comparison result" further includes: When Tao > Ta2 and Pdt ≥ P2, control the other throttle valve to open, otherwise maintain the opening and closing states of the two throttle valves, and cycle in this way until Tao < Ta1, and / or Pdt < P1.

5. The control method of the air source heat pump unit according to claim 1, characterized in that, The step of "selectively controlling the opening and closing of the two throttle valves based on the comparison result" further includes: When Tao ≥ Ta1 and Pdt ≥ P1, control the two throttle valves to open.

6. The control method of the air source heat pump unit according to claim 5, characterized in that, After the step of "controlling the two throttle valves to open", it further includes: Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt; Compare the magnitude of the outdoor ambient temperature Tao with the first ambient temperature threshold Ta1 and the magnitude of the exhaust pressure saturation temperature Pdt with the first exhaust pressure saturation temperature threshold P1; When Tao < Ta1, and / or Pdt < P1, control one of the throttle valves to close, otherwise maintain the opening and closing states of the two throttle valves, and cycle in this way until Tao > Ta2 and Pdt ≥ P2.

7. The control method of the air source heat pump unit according to claim 6, characterized in that, After the step of "controlling one of the throttle valves to close", it further includes: Every first set time, obtain the outdoor ambient temperature Tao and the exhaust pressure saturation temperature Pdt; Compare the magnitude of the outdoor ambient temperature Tao with the second ambient temperature threshold Ta2 and the magnitude of the exhaust pressure saturation temperature Pdt with the second exhaust pressure saturation temperature threshold P2; When Tao > Ta2 and Pdt ≥ P2, control the opening of the two throttle valves; otherwise, maintain the opening and closing states of the two throttle valves, and loop until Tao < Ta1 and / or Pdt < P1.

8. The control method of the air source heat pump unit according to any one of claims 1-7, characterized in that After "selectively controlling the opening and closing of the two throttle valves", the control method further includes: After the throttle valve in the open state operates for a second set time, control this throttle valve to enter the automatic control mode.

9. The control method of the air source heat pump unit according to claim 8, characterized in that, The step of "controlling this throttle valve to enter the automatic control mode" further includes: Obtain the suction temperature T1 and the suction pressure saturation temperature T2 of the compressor; Based on the suction temperature T1 and the suction pressure saturation temperature T2, determine the opening adjustment amount Δeev of the throttle valve; Based on the opening adjustment amount Δeev, adjust the opening of the throttle valve; Loop in this way according to a third set time until the opening and closing state of any one of the throttle valves changes.

10. The control method of the air source heat pump unit according to claim 9, characterized in that, The step of "based on the suction temperature T1 and the suction pressure saturation temperature T2, determine the opening adjustment amount Δeev of the throttle valve" specifically includes: Based on the suction temperature T1 and the suction pressure saturation temperature T2, calculate the suction superheat SH; Among them, the calculation formula for the suction superheat SH is: SH = T1 - T2; Based on the suction superheat SH, determine the target value sh; Based on the suction superheat SH and the target value sh, calculate the deviation value ΔSH and the change rate ΔSH'; Among them, the calculation formula for the deviation value ΔSH is: ΔSH = SH' - sh; The calculation formula for the change rate ΔSH' is: ΔSH’ = SH’ - SH’ t-1 ; Based on the deviation value ΔSH and the change rate ΔSH', calculate the opening adjustment amount Δeev; Among them, the calculation formula for the opening adjustment amount Δeev is: Δeev = a1×ΔSH + b1×ΔSH'; Among them, SH’ is the suction superheat at the current moment; SH’ t -1 is the suction superheat at the previous moment; a1 and b1 are fitting formula coefficients.

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