An air source heat pump system

Abstract

The present application relates to an air source heat pump system, through the setting of combined liquid accumulator and the improved start-up and shutdown anti-liquid return control program matched with the combined liquid accumulator, the liquid return during the start-up process of the unit can be effectively avoided, the time from the start-up to the stable operation of the refrigeration system is shortened, the problem of liquid strike of the compressor during the start-up process is effectively solved, the reliability and service life of the unit are improved, and during the shutdown process of the compressor, the excessive refrigerant of the system is recycled to the combined liquid accumulator, so that the problem of excessive refrigerant of the unit during the next stage start-up for a short time is avoided.

Description

Technical Field

[0001] This invention relates to the field of heat pumps, and more particularly to an air source heat pump system. Background Technology

[0002] A heat pump system undergoes a refrigerant migration process from startup to stable operation. During this migration, the system may not immediately output stable cooling or heating capacity, or the output capacity may be relatively low. Taking cooling as an example, after the compressor starts, before the heat pump system can operate stably in cooling mode, a high-low pressure difference needs to be established between the condenser and evaporator. This process is described as follows:

[0003] The refrigerant in the receiver migrates to the compressor, and after the compressor performs work, it migrates to the condenser. After exchanging heat in the condenser, it flows through the expansion valve. After the flow rate is controlled by the expansion valve, it migrates to the evaporator. After exchanging cooling capacity in the evaporator, it migrates back to the compressor.

[0004] During the aforementioned migration cycle, the refrigerant establishes a high-low pressure difference between the condenser and evaporator until the system's high / low pressures reach a stable state and are maintained there, allowing the evaporator and condenser to continuously absorb and release heat. It is evident that in the process of establishing a suitable high-low pressure difference between the condenser and evaporator in a heat pump system, the compressor may experience severe liquid slugging due to the intake of a large amount of liquid refrigerant, thus affecting the compressor's lifespan. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide an air source heat pump system, which has a start-up anti-return operation control and a shutdown refrigerant recovery device, which has the advantage of avoiding excessive refrigerant in the compressor during the short period of start-up, thus preventing severe liquid slugging.

[0006] An air-source heat pump system includes a compressor, a four-way valve, a water-side heat exchanger, a combined liquid receiver, a control valve module, an air-side heat exchanger, and several temperature and pressure sensors connected via a refrigerant circulation pipeline, and a controller electrically and / or communicatively connected to the compressor, the control valve module, the temperature sensors, and the pressure sensors. The controller regulates the compressor and the control valve module using the following method:

[0007] When the controller receives the power-on command, it acquires the ambient temperature, determines the optimal low pressure value corresponding to the ambient temperature based on the preset optimal low pressure value database of refrigerant, and determines the initial opening degree of each valve in the control valve module based on the optimal low pressure value of refrigerant.

[0008] The compressor is started, the operating mode of the heat pump system is obtained, the starting sequence of each valve in the control valve module is determined according to the operating mode, and the start-up time of the compressor is obtained. According to the starting sequence, the start-up time, and the preset start-up waiting time of each valve, each valve is adjusted to the corresponding initial opening and started one by one. Furthermore, the low pressure value at the current moment is obtained, and the pressure difference between the optimal low pressure value and the low pressure value at the current moment is calculated. According to the pressure difference, the valve adjustment rate of each valve is determined, and the opening of each valve is adjusted to the opening required for stable operation of the heat pump system according to the corresponding valve adjustment rate within a first limited time.

[0009] Compared with the prior art, the present invention, through the combination liquid receiver and the improved start-up anti-backflow control program that works in conjunction with the combination liquid receiver, can effectively prevent backflow during the start-up of the unit, shorten the time from start-up to stable operation of the refrigeration system, effectively solve the problem of liquid slugging in the compressor during start-up, and improve the reliability and service life of the unit.

[0010] Furthermore, the combined liquid receiver includes two independent sealed chambers: one sealed chamber is a gas-liquid separation chamber, and the other is a liquid storage chamber. The gas-liquid separation chamber has a first through-hole and a second through-hole. The first through-hole is connected to the first intake control valve of the control valve module via a gas pipe, and the second through-hole is connected to the second intake control valve of the control valve module via a gas pipe. The first and second intake control valves control the refrigerant flow rate into and out of the gas-liquid separation chamber. The liquid storage chamber has a third through-hole and a fourth through-hole. The third through-hole is connected to the first electronic expansion valve of the control valve module via a liquid pipe, and the fourth through-hole is connected to the second electronic expansion valve of the control valve module via a liquid pipe. The first and second electronic expansion valves control the refrigerant flow rate into and out of the liquid storage chamber.

[0011] Furthermore, the controller's regulation of the compressor and control valve module also includes the following steps:

[0012] When the controller receives a shutdown command, it controls the compressor to operate at a reduced frequency. Based on the operating mode, it determines the closing sequence of each valve in the control valve module and obtains the frequency reduction elapsed time. Based on the closing sequence, the frequency reduction elapsed time, and the preset closing waiting time of each valve, it controls each valve to close within a second limited time.

[0013] This invention, through an improved shutdown anti-return control program that works in conjunction with the combined liquid receiver, recovers excess refrigerant from the system into the combined liquid receiver, effectively avoiding the problem of excessive refrigerant in the short time during the next stage of unit startup, and further enhancing the protection of the compressor to prevent liquid slugging during startup.

[0014] Furthermore, before regulating the compressor and control valve module, the controller also includes the detection of refrigerant leakage throughout the system, specifically:

[0015] Obtain the high pressure P of the refrigerant in the liquid storage chamber. H The low-pressure P of the refrigerant at the compressor return port L and the high pressure P H Low pressure P L Compared with the preset high pressure standard value P H S Low pressure standard value P L S Comparison:

[0016] When the high pressure P H Greater than or equal to the high pressure standard value P H S And low pressure P L Greater than or equal to the low-pressure standard value P L S When the value is reached, the control program for the compressor and control valve module is entered;

[0017] In other cases, a refrigerant leak alarm will be sent to the system, and the compressor will be stopped from starting.

[0018] This invention, by detecting refrigerant leaks in the entire system beforehand, ensures that the subsequent start-up and shutdown control programs achieve effective system backflow prevention.

[0019] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the migration of refrigerant in the air source heat pump system under the cooling mode of the present invention.

[0021] Figure 2 This is a schematic diagram illustrating the migration of refrigerant in the air source heat pump system under the heating mode of the present invention.

[0022] Figure 3 This is a schematic diagram of a combined liquid reservoir structure according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram showing the start-up and valve adjustment rates of each valve in the control valve module under the refrigeration mode of the present invention.

[0024] Figure 5 This is a schematic diagram showing the start-up and valve adjustment rates of each valve in the control valve module under the heating mode of this invention. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention.

[0026] To address the problem of excessive liquid refrigerant intake during compressor startup in heat pump systems, which leads to severe liquid slugging in the compressor, this invention proposes an air-source heat pump system. This system includes an improved start-up and shutdown anti-return control method and a combined liquid receiver.

[0027] For specific implementation details, please refer to [link / reference]. Figure 1 and Figure 2 The air source heat pump system proposed in this invention includes a compressor 10, a four-way valve 20, a water source heat exchanger 30, a combined liquid receiver 40, a control valve module 50, an air-side heat exchanger 60, a temperature sensor (not shown), a pressure acquisition module 80, a controller (not shown), and other auxiliary pipes. The compressor 10, four-way valve 20, water source heat exchanger 30, combined liquid receiver 40, control valve module 50, and air-side heat exchanger 60 are sequentially connected via refrigerant piping. The controller is electrically and / or communicatively connected to the compressor 10, control valve module 50, temperature sensor, and pressure acquisition module 80.

[0028] Please see Figure 3 The combined liquid reservoir 40 includes two independent sealed chambers arranged in concentric circles. The inner sealed chamber is a gas-liquid separation chamber 41, and the outer sealed chamber is a liquid storage chamber 42.

[0029] The gas-liquid separation chamber 41 is a cylindrical cavity with a sealed bottom, and its top cover has a first through hole and a second through hole. The gas-liquid separation chamber 41 also includes an inlet pipe 412 and an outlet pipe 413. One end of the inlet pipe 412 is inserted into the first through hole and communicates with the upper chamber of the gas-liquid separation chamber 41, and the other end is connected to the return port S of the four-way valve 20 via a refrigerant pipeline. One end of the outlet pipe 413 is configured as a U-shaped pipe, which is installed inside the gas-liquid separation chamber 41, with its U-shaped connection located at the bottom of the gas-liquid separation chamber 41. One end of the U-shaped pipe communicates with the upper chamber of the gas-liquid separation chamber 41, and the other end passes through the second through hole and is connected to the return port B of the compressor 10 via a refrigerant pipeline. The gas-liquid mixed refrigerant returning from the return port S of the four-way valve 20 enters the gas-liquid separation chamber 41 through the inlet pipe 412. Utilizing the difference in specific gravity between gas and liquid, the liquid refrigerant and a small amount of refrigeration oil carried by it sink under the action of gravity, while the gaseous refrigerant floats to the top, thereby achieving gas-liquid separation.

[0030] Furthermore, the U-shaped tube is provided with an oil return filter hole 414 at the U-shaped connection, so that the gaseous refrigerant generates a certain negative pressure when flowing through the oil return filter hole 414. Under the action of negative pressure, a certain amount of refrigeration oil is drawn in. When the refrigeration oil flows back to the compressor with the gaseous refrigerant, it lubricates the compressor and ensures the normal operation of the compressor.

[0031] The liquid storage chamber 42 is a bottom-sealed annular cylindrical cavity with a third and a fourth through hole on its top cover. This annular cylindrical cavity is concentric with the cylindrical cavity of the gas-liquid separation chamber 41, and its inner diameter is slightly larger than the outer diameter of the gas-liquid separation chamber 41, allowing the gas-liquid separation chamber 41 to be seamlessly fitted into the liquid storage chamber 42. The liquid storage chamber 42 also includes a first liquid pipe 422 and a second liquid pipe 423. One end of the first liquid pipe 422 is inserted into the third through hole and communicates with the lower chamber of the liquid storage chamber 42; its other end is connected to the water source side heat exchanger 30 via a refrigerant pipe. One end of the second liquid pipe 423 is inserted into the fourth through hole and communicates with the lower chamber of the liquid storage chamber 42; its other end is connected to the air side heat exchanger 60 via a refrigerant pipe.

[0032] The combined liquid receiver 40, through heat exchange between the liquid receiver 42 and the gas-liquid separation chamber 41, allows the low-temperature, incompletely evaporated liquid refrigerant in the gas-liquid separation chamber 41 to absorb heat and evaporate again, preventing the compressor from drawing in liquid refrigerant and causing liquid slugging. At the same time, it can ensure a constant temperature in the gas-liquid separation chamber, effectively solving the problems of excessive viscosity of the refrigeration oil and separation of refrigeration oil and gaseous refrigerant at low system temperatures. The combined liquid receiver 40, through cold exchange between the gas-liquid separation chamber 41 and the liquid receiver 42, further subcools the high-pressure, medium-temperature liquid refrigerant in the liquid receiver 42, thereby improving the overall output capacity and energy efficiency ratio of the unit.

[0033] The control valve module 50 includes a first electronic expansion valve 51, a second electronic expansion valve 52, a first suction control valve 53, and a second suction control valve 54. The first electronic expansion valve 51 is located between the first liquid pipe 422 of the liquid storage chamber 42 and the refrigerant pipeline connecting the water source side heat exchanger 30, and is used to control the flow rate of liquid refrigerant flowing through the first liquid pipe 422. The second electronic expansion valve 52 is located between the second liquid pipe 423 of the liquid storage chamber 42 and the refrigerant pipeline connecting the air side heat exchanger 60, and is used to control the flow rate of liquid refrigerant flowing through the second liquid pipe 423. The first suction control valve 53 is located between the inlet pipe 412 of the gas-liquid separation chamber 41 and the refrigerant pipeline connecting the return port S of the four-way valve 20, and is used to control the flow rate of gaseous refrigerant flowing into the gas-liquid separation chamber 41. The second suction control valve 54 is located between the outlet pipe 413 of the gas-liquid separation chamber 41 and the return port B of the compressor 10, and is used to control the flow rate of gaseous refrigerant flowing into the compressor 10.

[0034] The temperature sensor is used to collect the ambient temperature signal and transmit the temperature signal to the controller. The location of the sensor is not limited in this application, as long as it can transmit the ambient temperature signal to the controller.

[0035] The pressure acquisition module 80 includes a first pressure sensor 81 and a second pressure sensor 82. The first pressure sensor 81 is disposed in the liquid storage chamber 42 and is used to measure the high pressure P of the high-pressure medium-temperature liquid refrigerant. H The pressure signal is transmitted to the controller. The second pressure sensor 82 is located at the return port B of the compressor 10 and is used to measure the low-pressure P of the low-temperature, low-pressure gaseous refrigerant. L It then transmits the pressure signal to the controller.

[0036] Please see Figure 1 and Figure 2 When the heat pump system is cooling, the high-temperature and high-pressure gaseous refrigerant enters the air-side heat exchanger 60 from the exhaust port A of the compressor 10 through the inlet D of the four-way valve 20 and the first working port E, and dissipates heat to become a high-pressure and medium-temperature liquid refrigerant. Then, it enters the liquid storage chamber 42 through the second electronic expansion valve 52 and the second liquid pipe 423 and exchanges heat with the gas-liquid separation chamber 41 to become a medium-pressure and medium-temperature liquid refrigerant. Then, it enters the water source side heat exchanger 30 through the first liquid pipe 422 and the first electronic expansion valve 51 to absorb heat and evaporate into a low-temperature and low-pressure gaseous refrigerant. Then, it enters the gas-liquid separation chamber 41 through the second working port C, the return port S, the first suction control valve 53, and the inlet pipe 412 of the four-way valve 20. It further absorbs heat from the liquid storage chamber 42 to evaporate the liquid refrigerant that has not been completely evaporated. Then, it carries the refrigeration oil back to the return port B of the compressor 10 through the outlet pipe 413.

[0037] When the heat pump system is heating, the high-temperature, high-pressure gaseous refrigerant enters the water source side heat exchanger 30 through the air inlet D of the four-way valve 20 and the second working air inlet C, where it exchanges heat with the water pipeline to become a high-pressure, medium-temperature liquid refrigerant. Then, it enters the liquid storage chamber 42 through the first electronic expansion valve 51 and the first liquid pipe 422, where it exchanges heat with the gas-liquid separation chamber 41 to become a medium-pressure, medium-temperature liquid refrigerant. After passing through the second liquid pipe 423 and the second electronic expansion valve 52 for throttling and pressure reduction, it enters the air side heat exchanger 60 to absorb heat and evaporate into a low-temperature, low-pressure gaseous refrigerant. Then, it enters the gas-liquid separation chamber 41 through the first working air inlet E, the return air inlet S, the first suction control valve 53, and the inlet pipe 412 of the four-way valve 20, where it further absorbs heat from the liquid storage chamber 42 to evaporate the liquid refrigerant that has not been completely evaporated. Finally, it carries the refrigerant oil back to the return air inlet B of the compressor 10 through the outlet pipe 413.

[0038] The controller receives system operating mode commands, temperature signals transmitted by temperature sensor 70 and pressure signals transmitted by pressure acquisition module 80, and sends start / stop signals to compressor 10, valve port reversal signals to four-way valve 20, and opening adjustment signals to control valve module 50.

[0039] The controller also includes a storage unit and a processing unit, wherein the storage unit is used to store a preset high-pressure standard value P. H S Low pressure standard value P L S The database includes: a preset database of optimal low-pressure refrigerant values; and a preset database of initial opening values ​​for the first electronic expansion valve 51, the second electronic expansion valve 52, the first intake control valve 53, and the second intake control valve 54, determined based on the optimal low-pressure refrigerant values; and the ambient temperature T collected by the temperature sensor 70 at each time point. E t The first pressure sensor 81 collects the high pressure P. H t The second pressure sensor 82 collects the low pressure P. L t The processing unit controls the start and stop of the compressor 10, the rotation of the four-way valve 20, and the opening adjustment and start / stop of the first electronic expansion valve 51, the second electronic expansion valve 52, the first suction control valve 53, and the second suction control valve 54. The processing unit calculates the pressure difference between the low-pressure value of the heat pump unit at the current moment and the refrigerant balance pressure value corresponding to the current ambient temperature, and determines the initial opening of the suction control valves and electronic expansion valves based on the pressure difference, thereby adjusting the opening of the suction control valves and electronic expansion valves.

[0040] Before starting the compressor, the controller first checks for refrigerant leaks throughout the system:

[0041] S00 obtains the high-pressure P of the refrigerant in the liquid storage chamber. H The low-pressure P of the refrigerant at the compressor return port L and the high pressure P H Low pressure P L Compared with the preset high pressure standard value P H S Low pressure standard value P L S Comparison:

[0042] When the high pressure P H Greater than or equal to the high pressure standard value P H S And low pressure P L Greater than or equal to the low-pressure standard value PL S When the value is reached, execute steps S10 to S30;

[0043] In other cases, a refrigerant leak alarm will be sent to the system, and the compressor will be stopped from starting.

[0044] Next, please refer to Figure 4 The controller controls the start and stop of the compressor 10 of the heat pump system, as well as the start and stop and opening degree adjustment of the first electronic expansion valve 51, the second electronic expansion valve 52, the first suction control valve 53 and the second suction control valve 54 through the following steps.

[0045] S10 receives the power-on command and obtains the ambient temperature T. E And determine the ambient temperature T based on the preset optimal low pressure value database of the refrigerant. E The corresponding optimal low-pressure value P L target And based on the optimal refrigerant low-pressure value P L target Determine the initial opening degree K of each valve in the control valve module. 0 .

[0046] Specifically, the optimal low pressure of the refrigerant is the evaporation pressure of the refrigeration system when the refrigerant operates most reliably and efficiently under the current ambient temperature.

[0047] The control valve module includes a first intake control valve, a second intake control valve, a first electronic expansion valve, and a second electronic expansion valve. The initial opening degree of the first intake control valve is K1. 0 The initial opening degree of the second intake control valve is K2. 0 The initial opening degree of the first electronic expansion valve is K3. 0 The initial opening degree of the second electronic expansion valve is K4. 0 .

[0048] S20 starts the compressor, obtains the operating mode of the heat pump system, determines the starting sequence of each valve in the control valve module according to the operating mode, and obtains the compressor's start-up elapsed time Δt. Based on the starting sequence, start-up elapsed time Δt, and the preset start-up waiting time Δt of each valve... i ON Control each valve to adjust to the corresponding initial opening degree K 0 Then, they are started one by one; and the current low-pressure value P is further obtained. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP Lt And based on the pressure difference ΔP L t Determine the valve adjustment rate for each valve, and control the valve opening according to the corresponding valve adjustment rate for the first limited time Δt1. 限定 Adjust the internal settings to the level required for stable operation of the heat pump system.

[0049] (I) Cooling Mode

[0050] Please see Figure 4 When the heat pump system is in cooling mode, the start-up sequence of the control valve module is as follows: first suction control valve, second suction control valve, first electronic expansion valve, and second electronic expansion valve. The specific start-up and opening adjustment are as follows.

[0051] When the start-up time Δt is equal to the start-up waiting time Δt1 of the first intake control valve ON-C At that time, the opening degree of the first intake control valve is adjusted to its initial opening degree K1. 0 Then, the first intake control valve is activated; and the current low-pressure value P is acquired in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔP L t Determine the valve adjustment rate R of the first intake control valve K1 And control the opening of the first intake control valve according to its valve adjustment rate R. K1 Adjust accordingly; at the same time, keep the other three valves closed.

[0052] When the start-up time Δt is equal to the start-up waiting time Δt2 of the second intake control valve ON-C At that time, the opening degree of the second intake control valve is adjusted to its initial opening degree K2. 0 Then activate the second intake control valve; and obtain the current low-pressure value P in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔP L t Determine the valve adjustment rate R of the second intake control valve K2 And control the opening of the second intake control valve according to its valve adjustment rate R.K2 Adjustments are made; at the same time, the first intake control valve is kept in the adjustment state, and the other two valves are kept in the closed state.

[0053] When the start-up time Δt is equal to the start-up waiting time Δt3 of the first electronic expansion valve ON-C At that time, the opening degree of the first electronic expansion valve is adjusted to its initial opening degree K3. 0 Then, the first electronic expansion valve is activated; and the current low-pressure value P is acquired in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔP L t Determine the valve adjustment rate R of the first electronic expansion valve K3 And control the opening of the first electronic expansion valve according to its valve adjustment rate R K3 Adjustments are made; at the same time, the first and second intake control valves are kept in the adjustment state, and the second electronic expansion valve is kept in the closed state.

[0054] When the start-up time Δt is equal to the start-up waiting time Δt4 of the second electronic expansion valve ON-C At that time, the opening degree of the second electronic expansion valve is adjusted to its initial opening degree K4. 0 Then the second electronic expansion valve is activated; and the current low-pressure value P is acquired in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔP L t Determine the valve adjustment rate R of the second electronic expansion valve K4 And control the opening of the second electronic expansion valve according to its valve adjustment rate R. K4 Adjustments are made; at the same time, the first intake control valve, the second intake control valve, and the first electronic expansion valve are kept in the adjustment state.

[0055] When the start-up time Δt is equal to the first limited time Δt1 of the anti-backflow control during startup. 限定At the same time, the opening degree of the first intake control valve and the second intake control valve are adjusted to the opening degree required for the stable operation of the heat pump system; the opening degree of the first electronic expansion valve is adjusted to the opening degree required for the PID control program for the stable operation of the heat pump system; and the opening degree of the second electronic expansion valve is adjusted to the fully open mode.

[0056] The Δt1 ON-C Δt2 ON-C Δt3 ON-C and Δt4 ON-C Satisfy Δt1 ON-C <Δt2 ON-C <Δt3 ON-C <Δt4 ON-C <Δt1 限定 , where Δt1 限定 The value range is from 5 min to 7 min.

[0057] (II) Heating Mode

[0058] Please see Figure 5 When the heat pump system is in heating mode, the start-up sequence of the control valve module is: first suction control valve, second suction control valve, second electronic expansion valve, and first electronic expansion valve. The start-up and opening adjustment of the first and second suction control valves are the same as those in the cooling mode. The start-up sequence of the first and second electronic expansion valves is different from that in the cooling mode. The specific differences are as follows.

[0059] When the start-up time Δt is equal to the start-up waiting time Δt1 of the first intake control valve ON-H At that time, the opening degree of the first intake control valve is adjusted to its initial opening degree K1. 0 Then, the first intake control valve is activated; and the current low-pressure value P is acquired in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔP L t Determine the valve adjustment rate R of the first intake control valve K1 And control the opening of the first intake control valve according to its valve adjustment rate R. K1 Adjust accordingly; at the same time, keep the other three valves closed.

[0060] When the start-up time Δt is equal to the start-up waiting time Δt2 of the second intake control valve ON-H At that time, the opening degree of the second intake control valve is adjusted to its initial opening degree K2.0 Then activate the second intake control valve; and obtain the current low-pressure value P in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔP L t Determine the valve adjustment rate R of the second intake control valve K2 And control the opening of the second intake control valve according to its valve adjustment rate R. K2 Adjustments are made; at the same time, the first intake control valve is kept in the adjustment state, and the other two valves are kept in the closed state.

[0061] When the start-up time Δt is equal to the start-up waiting time Δt4 of the second electronic expansion valve ON-H At that time, the opening degree of the second electronic expansion valve is adjusted to its initial opening degree K4. 0 Then the second electronic expansion valve is activated; and the current low-pressure value P is acquired in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔP L t Determine the valve adjustment rate R of the second electronic expansion valve K4 And control the opening of the second electronic expansion valve according to its valve adjustment rate R. K4 Adjustments are made; at the same time, the first intake control valve and the second intake control valve are kept in the adjustment state, and the first electronic expansion valve is kept in the closed state.

[0062] When the start-up time Δt is equal to the start-up waiting time Δt3 of the first electronic expansion valve ON-H At that time, the opening degree of the first electronic expansion valve is adjusted to its initial opening degree K3. 0 Then, the first electronic expansion valve is activated; and the current low-pressure value P is acquired in real time. L t And calculate the optimal low-pressure value P. L target Compared with the current low pressure value P L t Pressure difference ΔP L t And based on the pressure difference ΔPL t Determine the valve adjustment rate R of the first electronic expansion valve K3 And control the opening of the second electronic expansion valve according to its valve adjustment rate R. K3 Adjustments are made; at the same time, the first intake control valve, the second intake control valve, and the second electronic expansion valve are kept in the adjustment state.

[0063] When the start-up time Δt is equal to the first limited time Δt1 of the anti-backflow control during startup. 限定 At the same time, the opening degree of the first intake control valve and the second intake control valve are adjusted to the opening degree required for the stable operation of the heat pump system; the opening degree of the second electronic expansion valve is adjusted to the opening degree required for the PID control program for the stable operation of the heat pump system; and the opening degree of the first electronic expansion valve is adjusted to the fully open mode.

[0064] The Δt1 ON-H Δt2 ON-H Δt3 ON-H and Δt4 ON-H Satisfy Δt1 ON-H <Δt2 ON-H <Δt4 ON-H <Δt3 ON-H <Δt1 限定 , where Δt1 限定 The value range is from 5 min to 7 min.

[0065] S30 receives a shutdown command, controls the compressor to operate at a reduced frequency, determines the closing sequence of each valve in the control valve module according to the operating mode, and obtains the time Δt elapsed since the frequency reduction. J According to the shutdown sequence and the frequency reduction time Δt J The preset closing waiting time Δt for each valve i OFF Control each valve at the second defined time Δt2 限定 Internally closed.

[0066] (I) Cooling Mode

[0067] Please see Figure 4 When the heat pump system is in cooling mode, the closing sequence of the control valve module is as follows: first, close the first electronic expansion valve, then simultaneously close the first suction control valve, the second suction control valve, and the second electronic expansion valve. The specific closing situation is as follows.

[0068] When the frequency reduction has elapsed for time Δt J Equal to the first electronic expansion valve waiting time Δt3 OFF-C At the same time, the first electronic expansion valve is closed; simultaneously, the first intake control valve, the second intake control valve, and the second electronic expansion valve are kept in a frequency reduction regulation state.

[0069] When the compressor completely stops outputting air, the first suction control valve, the second suction control valve, and the second electronic expansion valve are simultaneously closed.

[0070] (II) Heating Mode

[0071] Please see Figure 5 When the heat pump system is in heating mode, the closing sequence of the control valve module is as follows: first, close the second electronic expansion valve, then simultaneously close the first suction control valve, the second suction control valve, and the first electronic expansion valve. The specific closing situation is as follows.

[0072] When the frequency reduction has elapsed for time Δt J Equal to the second electronic expansion valve waiting time Δt4 OFF-H At the same time, the second electronic expansion valve is closed; simultaneously, the first intake control valve, the second intake control valve, and the first electronic expansion valve are kept in a frequency reduction regulation state.

[0073] When the compressor completely stops outputting air, the first suction control valve, the second suction control valve, and the first electronic expansion valve are simultaneously closed.

[0074] The air source heat pump system described in this application, through the setting of a gas-liquid separation chamber and the intake control valve and electronic expansion valve that control the gas and liquid flow rates respectively, combined with the designed start-up anti-return control program and shutdown anti-return control program, can effectively solve the problem of the heat pump system drawing in too much liquid refrigerant when the compressor starts, which leads to severe liquid slugging of the compressor.

[0075] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. An air-source heat pump system, comprising a compressor, a four-way valve, a water-side heat exchanger, a combined liquid receiver, a control valve module, an air-side heat exchanger, and several temperature and pressure sensors connected via a refrigerant circulation pipeline, and a controller electrically and / or communicatively connected to the compressor, the control valve module, the temperature sensors, and the pressure sensors, characterized in that, The combined liquid receiver includes two independent sealed chambers: one is a gas-liquid separation chamber, and the other is a liquid storage chamber. The gas-liquid separation chamber and the liquid storage chamber are arranged concentrically from the inside out. The gas-liquid separation chamber is connected to the return port of a four-way valve through a first intake control valve of the control valve module, and to the return port of a compressor through a second intake control valve of the control valve module. The liquid storage chamber is connected to a water source-side heat exchanger through a first electronic expansion valve of the control valve module, and to an air-side heat exchanger through a second electronic expansion valve of the control valve module. The controller regulates the compressor and control valve module using the following method: When the controller receives the power-on command, it acquires the ambient temperature, determines the optimal low pressure value corresponding to the ambient temperature based on the preset optimal low pressure value database of refrigerant, and determines the initial opening degree of each valve in the control valve module based on the optimal low pressure value of refrigerant. The compressor is started, the operating mode of the heat pump system is obtained, the starting sequence of each valve in the control valve module is determined according to the operating mode, and the start-up time of the compressor is obtained. According to the starting sequence, the start-up time, and the preset start-up waiting time of each valve, each valve is adjusted to the corresponding initial opening and started one by one. Furthermore, the low pressure value at the current moment is obtained, and the pressure difference between the optimal low pressure value and the low pressure value at the current moment is calculated. According to the pressure difference, the valve adjustment rate of each valve is determined, and the opening of each valve is adjusted to the opening required for stable operation of the heat pump system according to the corresponding valve adjustment rate within a first limited time.

2. The air source heat pump system according to claim 1, characterized in that, The combined liquid receiver includes two independent sealed chambers: one sealed chamber is a gas-liquid separation chamber, and the other sealed chamber is a liquid storage chamber. The gas-liquid separation chamber has a first through hole and a second through hole. The first through hole is connected to the first intake control valve of the control valve module via an air pipe, and the second through hole is connected to the second intake control valve of the control valve module via an air pipe. The first and second intake control valves control the refrigerant flow rate into and out of the gas-liquid separation chamber. The liquid storage chamber has a third through hole and a fourth through hole. The third through hole is connected to the first electronic expansion valve of the control valve module via a liquid pipe, and the fourth through hole is connected to the second electronic expansion valve of the control valve module via a liquid pipe. The first and second electronic expansion valves control the refrigerant flow rate into and out of the liquid storage chamber.

3. The air source heat pump system according to claim 2, characterized in that, When the heat pump system is operating in cooling mode, the controller controls the first suction control valve, the second suction control valve, the first electronic expansion valve, and the second electronic expansion valve to start sequentially using the following method: When the startup has elapsed time Equal to the first intake control valve start-up waiting time At that time, the opening degree of the first intake control valve is adjusted to its initial opening degree. Then activate the first intake control valve; at the same time, keep the other three valves closed. When the startup has elapsed time Equal to the second intake control valve start-up waiting time At that time, the opening degree of the second intake control valve is adjusted to its initial opening degree. Then activate the second intake control valve; at the same time, keep the first intake control valve in the adjustment state and keep the other two valves in the closed state. When the startup has elapsed time Equal to the first electronic expansion valve start-up waiting time At that time, the opening degree of the first electronic expansion valve is adjusted to its initial opening degree. Then activate the first electronic expansion valve; at the same time, keep the first and second intake control valves in the adjustment state and keep the second electronic expansion valve in the closed state. When the startup has elapsed time Equal to the second electronic expansion valve start-up waiting time At that time, the opening degree of the second electronic expansion valve is adjusted to its initial opening degree. Then activate the second electronic expansion valve; at the same time, keep the first intake control valve, the second intake control valve, and the first electronic expansion valve in the adjustment state. When the startup has elapsed time Equal to the first time limit of the anti-backflow control upon startup At the same time, the opening degree of the first intake control valve and the second intake control valve are adjusted to the opening degree required for the stable operation of the heat pump system; the opening degree of the first electronic expansion valve is adjusted to the opening degree required by the PID control program for the stable operation of the heat pump system. The opening of the second electronic expansion valve is adjusted to the fully open mode.

4. The air source heat pump system according to claim 3, characterized in that, The , , and satisfy ,in The value range is 5min~7min.

5. The air source heat pump system according to claim 2, characterized in that, When the heat pump system is in heating mode, the controller controls the first suction control valve, the second suction control valve, the first electronic expansion valve, and the second electronic expansion valve to start sequentially using the following method: When the startup has elapsed time Equal to the first intake control valve start-up waiting time At that time, the opening degree of the first intake control valve is adjusted to its initial opening degree. Then activate the first intake control valve; at the same time, keep the other three valves closed. When the startup has elapsed time Equal to the second intake control valve start-up waiting time At that time, the opening degree of the second intake control valve is adjusted to its initial opening degree. Then activate the second intake control valve; at the same time, keep the first intake control valve in the adjustment state and keep the other two valves in the closed state. When the startup has elapsed time Equal to the second electronic expansion valve start-up waiting time At that time, the opening degree of the second electronic expansion valve is adjusted to its initial opening degree. Then activate the second electronic expansion valve; at the same time, keep the first and second intake control valves in the adjustment state and keep the first electronic expansion valve in the closed state. When the startup has elapsed time Equal to the first electronic expansion valve start-up waiting time At that time, the opening degree of the first electronic expansion valve is adjusted to its initial opening degree. Then activate the first electronic expansion valve; at the same time, keep the first intake control valve, the second intake control valve, and the second electronic expansion valve in the adjustment state. When the startup has elapsed time Equal to the first time limit of the anti-backflow control upon startup At the same time, the opening degree of the first intake control valve and the second intake control valve are adjusted to the opening degree required for the stable operation of the heat pump system; the opening degree of the second electronic expansion valve is adjusted to the opening degree required for the PID control program for the stable operation of the heat pump system; and the opening degree of the first electronic expansion valve is adjusted to the fully open mode.

6. The air source heat pump system according to claim 3, characterized in that, The , , and satisfy ,in The value range is 5min~7min.

7. The air source heat pump system according to any one of claims 1 to 6, characterized in that, The controller regulating the compressor and control valve module also includes the following steps: When the controller receives a shutdown command, it controls the compressor to operate at a reduced frequency. Based on the operating mode, it determines the closing sequence of each valve in the control valve module and obtains the frequency reduction elapsed time. Based on the closing sequence, the frequency reduction elapsed time, and the preset closing waiting time of each valve, it controls each valve to close within a second limited time.

8. The air source heat pump system according to claim 7, characterized in that, When the heat pump system is operating in cooling mode, the controller regulates the control valve module using the following method: When the frequency reduction has elapsed for a period of time Equal to the first electronic expansion valve waiting time to close At the same time, the first electronic expansion valve is closed; simultaneously, the first intake control valve, the second intake control valve, and the second electronic expansion valve are kept in a frequency reduction regulation state. When the compressor completely stops outputting air, the first suction control valve, the second suction control valve, and the second electronic expansion valve are simultaneously closed.

9. The air source heat pump system according to claim 7, characterized in that, When the heat pump system is in heating mode, the controller regulates the control valve module using the following method: When the frequency reduction has elapsed for a period of time Equal to the waiting time for the second electronic expansion valve to close. At the same time, the second electronic expansion valve is closed; simultaneously, the first intake control valve, the second intake control valve, and the first electronic expansion valve are kept in a frequency reduction regulation state. When the compressor completely stops outputting air, the first suction control valve, the second suction control valve, and the first electronic expansion valve are simultaneously closed.

10. The air source heat pump system according to any one of claims 2 to 6, 8, and 9, characterized in that, Before regulating the compressor and control valve modules, the controller also includes the detection of refrigerant leakage throughout the system, specifically: Obtain the high pressure of the refrigerant in the liquid storage chamber. Low pressure of refrigerant at compressor return port and the high pressure Low pressure Compared with the preset high pressure standard value Low pressure standard value Comparison: When the high pressure Greater than or equal to the high pressure standard value And low pressure Greater than or equal to the low-pressure standard value When the value is reached, the control program for the compressor and control valve module is entered; In other cases, a refrigerant leak alarm will be sent to the system, and the compressor will be stopped from starting.

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