Air source heat pump cold shield control method and control system

Abstract

The present application relates to air source heat pump technical field, disclose a kind of air source heat pump cold shield control method and control system.The method is in the first start-up stage of compressor, according to the inlet temperature of economizer main passage and the outlet temperature of economizer main passage determines the heat exchange state of economizer;When economizer does not reach preset heat exchange state, according to compressor nest heart temperature control liquid injection circuit, so that supercooled liquid refrigerant is selectively injected into compressor air inlet after throttling;When economizer reaches preset heat exchange state, prohibit liquid injection, and the medium-temperature medium-pressure gaseous refrigerant formed by the heat exchange of economizer auxiliary passage is transported to air inlet.In the process of injection enthalpy increase, target intermediate pressure is determined according to condensing pressure and evaporating pressure, and the opening of second electronic expansion valve is adjusted according to the pressure deviation of intermediate pressure relative to target intermediate pressure.The present application can timely limit the temperature rise of compressor nest heart before economizer air supply is established, and improve the intermediate pressure regulation accuracy, and give consideration to compressor protection and system energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of heat pump control technology, specifically to an air source heat pump cold shield control method and control system. Background Technology

[0002] With the continuous advancement of energy conservation and emission reduction policies and the ever-growing demand for clean energy heating, air source heat pumps, due to their advantages such as energy saving, high efficiency, and safety, have been widely used in building heating, domestic hot water, and industrial cold and heat sources. Especially in cold northern regions, to meet heating demands at low ambient temperatures, air source heat pumps need to operate stably for extended periods under conditions of both low ambient temperatures and high supply water temperatures. Therefore, higher requirements are placed on the low-temperature heating capacity, operational reliability, and energy efficiency of air source heat pump systems.

[0003] To improve the heating performance of air source heat pumps at low ambient temperatures, existing technologies typically employ Enhanced Vapor Injection (EVI) technology. This technology generally utilizes an economizer to throttle and exchange heat through a portion of the liquid refrigerant, forming a medium-temperature, medium-pressure refrigerant, which is then injected into the compressor. This reduces the compressor's discharge temperature, increases the compressor's mass flow rate, improves the compressor's operating performance under low-temperature conditions, and enhances the heating capacity and operating efficiency of the air source heat pump.

[0004] However, research has found that existing air-source heat pumps with enthalpy booster still have the following problems under high compression ratio conditions such as ultra-low ambient temperature and high water supply temperature, especially during the initial start-up phase of the unit: Because the exhaust temperature sensor is located on the exhaust pipe, it is affected by factors such as ambient temperature, compressor casing and heat absorption of refrigeration oil. The exhaust temperature cannot reflect the actual thermal state inside the compressor in a timely manner. At this time, the air-boosting circuit has not yet established a stable air-boosting flow, which causes the temperature inside the compressor, especially in the core area, to rise rapidly. This can easily cause carbonization of refrigeration oil, decreased lubrication performance and abnormal wear of the scroll plate, affecting the operating reliability and service life of the compressor.

[0005] In addition, existing gas injection enthalpy enhancement systems typically adjust the gas injection volume based on exhaust temperature or fixed control parameters, lacking coordinated control of operating parameters such as condensing pressure, evaporating pressure, and intermediate pressure. This makes it difficult to adjust the gas injection volume in real time according to the actual operating status of the system, causing the gas injection pressure to easily deviate from the optimal operating range. This not only affects the system's energy efficiency but may also increase the mechanical load on the compressor and reduce the system's operational stability.

[0006] Therefore, how to solve the problems of excessively high internal compressor temperature, insufficient compressor protection, low operational reliability, and difficulty in balancing compressor safety and system energy efficiency in the initial start-up of existing air-source heat pumps with gas injection and enthalpy enhancement under ultra-low temperature and high water temperature conditions, due to the lag in exhaust temperature feedback and the lack of establishment of the gas injection circuit, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] This invention provides a cold shield control method and control system for air source heat pumps to solve the problems of existing air source heat pumps with gas replenishment and enthalpy enhancement during ultra-low temperature and high water temperature operation. During the initial start-up phase, the gas replenishment circuit is established slowly, the exhaust temperature cannot reflect the internal thermal state of the compressor in time, resulting in excessively high compressor core temperature, poor compressor protection effect, insufficient intermediate pressure regulation accuracy, and difficulty in achieving both system energy efficiency and performance.

[0008] This invention provides a cold shield control method for an air source heat pump, applicable to an air source heat pump, wherein the air source heat pump is equipped with a compressor, an economizer, a gas injection circuit, and a liquid injection circuit, and includes the following steps: During the initial startup phase of the air source heat pump, the compressor core temperature, economizer main channel inlet temperature, and economizer main channel outlet temperature are obtained. The heat exchange state of the economizer is determined based on the inlet temperature of the main channel of the economizer and the outlet temperature of the main channel of the economizer. When the economizer heat exchange state indicates that the economizer has not reached the preset heat exchange state, the liquid injection circuit is selectively turned on according to the compressor core temperature, so that the subcooled liquid refrigerant is injected into the compressor's gas inlet through the liquid injection circuit to reduce the compressor core temperature. When the economizer heat exchange state indicates that the economizer has reached the preset heat exchange state, the liquid injection circuit is controlled to close, and the gas supply circuit is controlled to deliver the medium-temperature and medium-pressure gaseous refrigerant formed by the economizer heat exchange to the gas supply port, so as to switch the compressor from liquid injection cooling control to gas injection enthalpy increase control. During the jet enthalpy control process, the condensing pressure, evaporating pressure, and intermediate pressure of the air source heat pump are acquired. The target intermediate pressure is determined based on the condensing pressure and the evaporating pressure. The amount of gas supplied to the gas supply circuit is adjusted based on the pressure deviation of the intermediate pressure relative to the target intermediate pressure.

[0009] Beneficial effects: By directly obtaining the compressor core temperature during the initial start-up phase and using the liquid injection circuit to cool the compressor before the economizer establishes the preset heat exchange state, the effects of lag in exhaust pipe temperature feedback and slow establishment of the gas injection circuit on compressor protection can be bypassed, thus promptly suppressing the temperature rise in the compressor core area. By controlling the switching between liquid injection cooling and gas injection enthalpy enhancement under the economizer heat exchange state, the compressor can obtain continuous cooling protection during the start-up phase and the operation phase after the gas injection circuit stabilizes. At the same time, by adjusting the gas injection volume according to the condensing pressure, evaporating pressure, and intermediate pressure, the intermediate pressure can be matched with the current operating conditions, thereby balancing the compressor's operational safety and the air source heat pump's operational efficiency.

[0010] According to some embodiments of the present invention, determining the heat exchange state of the economizer based on the inlet temperature and outlet temperature of the main channel of the economizer includes: Determine the economizer temperature difference between the inlet temperature of the main channel of the economizer and the outlet temperature of the main channel of the economizer; When the temperature difference of the economizer is greater than the preset temperature difference threshold, it is determined that the economizer has reached the preset heat exchange state.

[0011] Beneficial effects: The temperature difference between the inlet and outlet temperatures of the economizer's main channel reflects the actual heat exchange level within the economizer, thus it can be used to determine whether the gas injection circuit has established stable heat exchange and gas injection conditions. Compared to switching based solely on a preset start-up time, this method determines the switching timing based on the actual refrigerant cycle establishment process, reducing the premature intervention of jet enthalpy enhancement control or the delayed exit of liquid injection cooling control.

[0012] According to some embodiments of the present invention, the selective activation of the injection circuit based on the compressor core temperature includes: When the compressor core temperature exceeds the first temperature threshold, the liquid injection circuit is activated. When the compressor core temperature is lower than the second temperature threshold, the liquid injection circuit is shut down. Wherein, the second temperature threshold is less than the first temperature threshold, and when the compressor core temperature is between the second temperature threshold and the first temperature threshold, the current open / closed state of the injection circuit is maintained.

[0013] Beneficial effects: By forming a temperature hysteresis between the first and second temperature thresholds, the liquid injection circuit can be opened in time when the compressor core temperature is too high and closed after the compressor core temperature drops, thereby maintaining the compressor core temperature within a safe range; maintaining the current open and closed state of the liquid injection circuit between the two temperature thresholds can also avoid frequent opening and closing of the solenoid valve when the compressor core temperature fluctuates near the critical value, thus improving the stability of liquid injection control.

[0014] According to some embodiments of the present invention, the inlet of the liquid injection circuit is connected to the subcooled liquid refrigerant pipeline upstream of the main channel inlet of the economizer, the outlet of the liquid injection circuit is connected to the gas injection port of the compressor, and the liquid injection circuit is provided with a solenoid valve and a throttling element. The selective activation of the liquid injection circuit based on the compressor core temperature includes controlling the opening or closing of the solenoid valve so that the subcooled liquid refrigerant is injected into the gas inlet after being throttled by the throttling element.

[0015] Beneficial effects: The liquid injection circuit directly introduces subcooled liquid refrigerant upstream of the economizer's main channel inlet, and delivers it to the compressor's gas injection port via a solenoid valve and throttling element. This allows for the rapid establishment of an independent cooling refrigerant flow path during the initial startup of the air source heat pump, even before regular gas injection is established. After throttling and pressure reduction, the subcooled liquid refrigerant vaporizes and absorbs heat inside the compressor, directly reducing the temperature of the core region and improving the protection response speed during startup.

[0016] According to some embodiments of the present invention, determining the target intermediate pressure based on the condensation pressure and the evaporation pressure includes: determining the square root of the product of the condensation pressure and the evaporation pressure as the target intermediate pressure.

[0017] Beneficial effects: Condensation pressure and evaporation pressure vary with ambient temperature, outlet water temperature and load. Using the square root of their product as the target intermediate pressure allows the target intermediate pressure to change synchronously with the actual high and low pressure conditions of the air source heat pump, reducing the deviation from the operating conditions caused by using a fixed intermediate pressure setpoint. This provides a target benchmark that matches the current operating conditions for adjusting the gas supply, thus helping the air source heat pump to operate in a higher energy efficiency range.

[0018] According to some embodiments of the present invention, adjusting the air supply amount of the air supply circuit based on the pressure deviation between the intermediate pressure and the target intermediate pressure includes: The difference between the intermediate pressure and the target intermediate pressure is defined as the pressure deviation; When the pressure deviation is greater than the preset pressure deviation threshold, the opening of the second electronic expansion valve in the gas replenishment circuit is reduced. When the pressure deviation is less than the negative value of the preset pressure deviation threshold, the opening of the second electronic expansion valve is increased; When the pressure deviation is between the negative value of the preset pressure deviation threshold and the preset pressure deviation threshold, the current opening of the second electronic expansion valve is maintained.

[0019] Beneficial effects: By increasing or decreasing the opening of the second electronic expansion valve according to the direction of the pressure deviation, the intermediate pressure can be adjusted towards the target intermediate pressure. When the pressure deviation is within the preset range, maintaining the current opening of the second electronic expansion valve can form a dead zone for intermediate pressure adjustment, avoiding repeated operation of the second electronic expansion valve due to small pressure fluctuations. This improves the stability of the air supply circuit while ensuring the accuracy of intermediate pressure adjustment.

[0020] According to some embodiments of the present invention, adjusting the amount of gas replenishment in the gas replenishment circuit based on the pressure deviation between the intermediate pressure and the target intermediate pressure includes: using the difference between the intermediate pressure and the target intermediate pressure as the input of proportional-integral-derivative (PID) control, and adjusting the opening of the second electronic expansion valve in the gas replenishment circuit based on the output of the PID control.

[0021] Beneficial effects: By introducing the pressure deviation between the intermediate pressure and the target intermediate pressure into proportional-integral-derivative control, the opening of the second electronic expansion valve can be continuously corrected according to the current value and cumulative change of the pressure deviation. This allows the air supply to be dynamically adjusted according to the load and high and low pressure status of the air source heat pump, thereby reducing the steady-state deviation and regulation fluctuation of the intermediate pressure, and improving the control accuracy of the intermediate pressure and the system energy efficiency.

[0022] According to some embodiments of the present invention, the air source heat pump cooling shield control method further includes: When the intermediate pressure is greater than the difference between the preset intermediate pressure limit and the preset protection margin, the opening of the second electronic expansion valve is reduced. When the opening of the second electronic expansion valve is reduced, if the intermediate pressure is still greater than the difference between the preset intermediate pressure limit and the preset protection margin, the operating frequency of the compressor is reduced.

[0023] Beneficial effects: When the intermediate pressure approaches the preset intermediate pressure limit, the amount of supplementary gas is first reduced by decreasing the opening of the second electronic expansion valve. If the intermediate pressure still cannot be reduced, the compressor operating frequency is further reduced, thus forming a graded pressure protection system from supplementary gas regulation to compressor frequency reduction. This graded protection can limit the pressure and axial load on the compressor's intermediate pressure chamber, reducing the risk of abnormal wear or fatigue damage to the scroll components.

[0024] According to some embodiments of the present invention, a one-way valve is provided upstream of the air inlet of the compressor, which only allows refrigerant to flow toward the air inlet, and the one-way valve prevents liquid refrigerant from flowing back to the intermediate pressure chamber of the compressor when the air source heat pump is stopped.

[0025] Beneficial effects: The one-way valve restricts the refrigerant to flow only toward the compressor's gas inlet. When the air source heat pump is shut down for a long time, it can cut off the return path of liquid refrigerant to the compressor's intermediate pressure chamber, reduce the accumulation of liquid refrigerant in the compressor, thereby reducing the risk of liquid compression when the compressor restarts and improving the compressor's start-up reliability.

[0026] Secondly, this application also provides an air source heat pump cooling shield control system, including: a compressor, an economizer, a gas injection circuit, a liquid injection circuit, a temperature detection component, a pressure detection component, and a controller; the compressor is provided with a gas injection port; the economizer has a main channel and an auxiliary channel for mutual heat exchange; the inlet of the gas injection circuit is connected to a subcooled liquid refrigerant pipeline upstream of the main channel inlet of the economizer, and the outlet of the gas injection circuit is connected to the gas injection port; a second electronic expansion valve and the auxiliary channel are sequentially arranged in the gas injection circuit along the refrigerant flow direction; the liquid injection circuit has an inlet connected to the subcooled liquid refrigerant pipeline, and an outlet connected to the gas injection port; the liquid injection circuit is provided with a solenoid valve and a throttling element; the temperature detection component includes a core temperature sensor, an economizer main channel inlet temperature sensor, and an economizer main channel outlet temperature sensor; the pressure detection component includes a condensing pressure sensor, an evaporating pressure sensor, and an intermediate pressure sensor; the controller is electrically connected to the second electronic expansion valve, the solenoid valve, the temperature detection component, and the pressure detection component respectively; During the initial start-up phase of the compressor, the controller determines the economizer heat exchange state based on the inlet temperature and outlet temperature of the main economizer channel. If the economizer heat exchange state indicates that the economizer has not reached the preset heat exchange state, the controller controls the opening or closing of the solenoid valve based on the compressor core temperature, allowing subcooled liquid refrigerant to be selectively injected into the gas injection port after being throttled by the throttling element. If the economizer heat exchange state indicates that the economizer has reached the preset heat exchange state, the controller prohibits the solenoid valve from opening and controls the second electronic expansion valve, allowing the medium-temperature, medium-pressure gaseous refrigerant formed through the auxiliary channel heat exchange to be delivered to the gas injection port. During the vapor injection enthalpy control process, the condensing pressure, the evaporating pressure, and the intermediate pressure are acquired. A target intermediate pressure is determined based on the condensing pressure and the evaporating pressure, and the opening of the second electronic expansion valve is adjusted based on the pressure deviation between the intermediate pressure and the target intermediate pressure.

[0027] Beneficial effects: Both the liquid injection circuit and the gas injection circuit can obtain subcooled liquid refrigerant upstream of the main channel inlet of the economizer. When the economizer has not yet established a preset heat exchange state, the controller can control the liquid injection circuit according to the compressor core temperature, allowing the subcooled liquid refrigerant to enter the gas injection port after throttling and vaporize to absorb heat. Therefore, cooling of the compressor core area can be achieved without waiting for the exhaust temperature to rise or for the gas injection circuit to establish a stable flow rate. When the economizer reaches the preset heat exchange state, the controller disables the liquid injection circuit and activates the gas injection circuit, automatically transitioning the compressor from liquid injection cooling during startup to vapor injection enthalpy enhancement during stable operation, thus providing continuous cooling protection for the compressor. The temperature detection component, the pressure detection component, and the controller form a closed-loop control relationship, enabling the controller to determine the switching timing between liquid injection cooling and vapor injection enthalpy enhancement based on the actual heat exchange state of the economizer, and to adjust the second electronic expansion valve based on the condensing pressure, evaporating pressure, and intermediate pressure. Therefore, the device can reduce the mismatch between the liquid injection stage and the gas replenishment stage caused by fixed time switching, and can also dynamically adjust the gas replenishment volume according to the high and low pressure conditions of the air source heat pump, thereby taking into account the compressor's operating safety, intermediate pressure regulation stability and system operating efficiency. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a system schematic diagram of an air source heat pump cooling shield control system provided in a second aspect embodiment of the present invention; Figure 2 This is a schematic diagram of the pressure and enthalpy values ​​of the air source heat pump cooling shield control system provided in the second aspect embodiment of the present invention under three-stage subcooling. Figure 3 This is a flowchart of the air source heat pump cold shield control method provided in the first aspect embodiment of the present invention; Explanation of reference numerals in the attached figures: 100. Compressor; 110. Core temperature sensor; 120. Air inlet; 130. Exhaust temperature sensor; 200. Economizer; 210. Economizer main channel inlet temperature sensor; 220. Economizer main channel outlet temperature sensor; 230. Second electronic expansion valve; 240. Intermediate pressure sensor; 250. First electronic expansion valve; 260. Condensing pressure sensor; 270. Evaporating pressure sensor; 300. Liquid injection circuit; 310. Solenoid valve; 320. Throttling element; 400. Air inlet circuit; 500. Finned heat exchanger; 600. Plate heat exchanger; 700. Drive module. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The initial start-up phase refers to the phase after the compressor 100 has entered operation from the shutdown state, but before the economizer 200 has reached the preset heat exchange state. It is not limited to the first start-up of the air source heat pump after it leaves the factory.

[0032] The compressor core temperature refers to the temperature inside the compressor 100, which can be detected by the core temperature sensor 110 located in the compressor core area or at a location with a stable heat transfer relationship with the core area.

[0033] In this embodiment, the economizer 200 has a main channel for conveying the main cycle liquid refrigerant and an auxiliary channel for conveying the makeup refrigerant. The refrigerant in the main channel and the refrigerant in the auxiliary channel can exchange heat without mixing. The inlet temperature of the main channel of the economizer 200 is denoted as... The outlet temperature of the main channel of the economic instrument 200 is recorded as Condensation pressure is denoted as Evaporation pressure is denoted as The intermediate pressure on the gas supply side of compressor 100 is denoted as .

[0034] Traditional air-source heat pumps with enthalpy-increasing refrigerant injection typically adjust the injection volume based on the exhaust temperature sensor 130 located on the compressor 100's exhaust pipe. Under conditions of low ambient temperature and high outlet water temperature, the air-source heat pump has a high compression ratio. After the compressor 100 starts, the exhaust pipe, compressor 100 casing, and refrigerant oil absorb exhaust heat, causing the exhaust temperature rise to lag behind the rise in the compressor 100's internal temperature. Simultaneously, the main cycle refrigerant has not yet fully flowed to the economizer 200, and the amount of medium-temperature refrigerant available for injection into the compressor 100 from the injection circuit 400 is limited. Therefore, relying solely on the exhaust temperature for protection is insufficient to effectively limit the compressor's core temperature.

[0035] Reference Figure 1 As shown, the arrows indicate the direction of refrigerant flow.

[0036] According to an embodiment of the present invention, an air source heat pump cold shield control system is provided. The air source heat pump cold shield control system is capable of implementing the following air source heat pump cold shield control method and includes a compressor 100, an economizer 200, a gas injection circuit 400, a liquid injection circuit 300, a temperature detection component, a pressure detection component, and a controller. To form a complete air source heat pump refrigerant cycle, the device may further include an oil separator, a four-way valve, a finned heat exchanger 500, a plate heat exchanger 600, a drive module 700, a first electronic expansion valve 250, a liquid receiver, a filter, a gas-liquid separator, and multiple one-way valves. The compressor 100 may be a variable frequency compressor, and the controller may be a variable frequency controller.

[0037] The compressor 100 has an intake port, an exhaust port, and a make-up air port 120. The exhaust port is connected to a four-way valve via an oil separator. The four-way valve is used to switch the connection between the compressor 100 and the finned heat exchanger 500 and the plate heat exchanger 600 according to the heating or cooling mode. The intake port can be connected to the refrigerant line located on the evaporator outlet side via a gas-liquid separator. The make-up air port 120 is connected to the outlet of the auxiliary channel of the economizer 200.

[0038] The first electronic expansion valve 250 is installed in the main refrigerant pipeline to throttle the liquid refrigerant after heat exchange in the main channel of the economizer 200. The inlet of the make-up gas circuit 400 is connected to the subcooled liquid refrigerant pipeline upstream of the inlet of the main channel of the economizer 200, and the outlet of the make-up gas circuit 400 is connected to the make-up gas port 120 of the compressor 100. The second electronic expansion valve 230 and the auxiliary channel of the economizer 200 are sequentially arranged along the refrigerant flow direction in the make-up gas circuit 400, and the outlet of the auxiliary channel of the economizer 200 is connected to the intermediate pressure chamber of the compressor 100 via the outlet of the make-up gas circuit 400 and the make-up gas port 120. Adjusting the opening of the second electronic expansion valve 230 can change the refrigerant flow rate through the auxiliary channel of the economizer 200 and into the make-up gas port 120.

[0039] The liquid injection circuit 300 and the gas supply circuit 400 cooperate with each other. The inlet of the liquid injection circuit 300 is connected to the subcooled liquid refrigerant pipeline upstream of the main channel inlet of the economizer 200, and can be specifically connected to a pipeline section that can obtain secondary subcooled liquid refrigerant; the outlet of the liquid injection circuit 300 is connected to the gas supply port 120 of the compressor 100. The liquid injection circuit 300 is equipped with a solenoid valve 310 and a throttling element 320. The throttling element 320 can be a capillary tube or a third electronic expansion valve. The solenoid valve 310 is used to quickly open or close the liquid injection circuit 300, and the throttling element 320 is used to throttle and reduce the pressure of the subcooled liquid refrigerant entering the liquid injection circuit 300.

[0040] A one-way valve, allowing refrigerant to flow only towards the gas supply port 120, is installed upstream of the gas supply port 120. In one embodiment, the one-way valve is located between the auxiliary channel outlet of the economizer 200 and the gas supply port 120. The gas supply circuit 400 and the liquid injection circuit 300 can merge into a pipe section communicating with the gas supply port 120 upstream of the one-way valve, or they can be connected to the gas supply port 120 respectively through a one-way structure that allows refrigerant to flow only towards the gas supply port 120. Thus, when the compressor 100 stops, it is possible to prevent liquid refrigerant from flowing back into the intermediate pressure chamber of the compressor 100 along the gas supply line.

[0041] The temperature detection assembly includes a core temperature sensor 110, an economizer main channel inlet temperature sensor 210, and an economizer main channel outlet temperature sensor 220. The core temperature sensor 110 is used to detect the compressor core temperature. The inlet temperature sensor 210 and the outlet temperature sensor 220 of the main channel of the economizer are used to detect... and The temperature sensing component may also include features for detecting exhaust temperature. The exhaust temperature sensor 130 is used to retain the conventional exhaust temperature protection function of the air source heat pump.

[0042] The pressure detection assembly includes a condensing pressure sensor 260, an evaporating pressure sensor 270, and an intermediate pressure sensor 240. The condensing pressure sensor 260 is installed on the high-pressure line on the condensing side and is used for detection. The evaporation pressure sensor 270 is installed on the low-pressure pipeline on the evaporation side for detection. The intermediate pressure sensor 240 is installed upstream of the intermediate pressure pipeline of the air supply circuit 400 or the air supply port 120, and is used to detect... .

[0043] The controller is electrically connected to the second electronic expansion valve 230, the solenoid valve 310, the temperature detection component, and the pressure detection component to receive temperature and pressure signals and output opening commands for the second electronic expansion valve 230 and opening / closing commands for the solenoid valve 310. The controller can also be electrically connected to the compressor 100, the first electronic expansion valve 250, and the throttling element 320 using a third electronic expansion valve to output compressor 100 frequency commands and corresponding valve opening commands. These electrical connections can be achieved directly via wiring harnesses or via the unit's communication bus.

[0044] The controller, during the initial start-up phase of compressor 100, according to... and Determine the heat exchange state of economizer 200. If economizer 200 has not reached the preset heat exchange state, the controller will... The controller controls the opening and closing of solenoid valve 310, allowing subcooled liquid refrigerant to be selectively injected into the gas injection port 120 after being throttled by throttling element 320. When the economizer 200 reaches the preset heat exchange state, the controller prevents solenoid valve 310 from opening and controls the second electronic expansion valve 230 to deliver the medium-temperature, medium-pressure gaseous refrigerant formed through heat exchange in the auxiliary channel of the economizer 200 to the gas injection port 120. During the vapor injection enthalpy control process, the controller also... and Determine the target intermediate pressure, and based on The opening of the second electronic expansion valve 230 is adjusted according to the pressure deviation relative to the target intermediate pressure.

[0045] With the above-described configuration, both the liquid injection circuit 300 and the gas replenishment circuit 400 can obtain subcooled liquid refrigerant upstream of the main channel inlet of the economizer 200. When the economizer 200 has not yet reached the preset heat exchange state, the liquid injection circuit 300 can cool the compressor 100 without waiting for the auxiliary channel of the economizer 200 to establish stable gas replenishment. After the economizer 200 reaches the preset heat exchange state, the controller switches the cooling method to vapor injection enthalpy enhancement formed through the auxiliary channel of the economizer 200, and uses the pressure detection component to form an intermediate pressure closed-loop regulation. This allows for seamless connection between the liquid injection protection during startup and the vapor injection enthalpy enhancement during stable operation.

[0046] In heating mode, the high-temperature, high-pressure gaseous refrigerant discharged from compressor 100 passes through an oil separator and a four-way valve into plate heat exchanger 600. Plate heat exchanger 600 acts as a condensing heat exchanger, where the refrigerant releases heat to the water side and condenses, forming a primary subcooled liquid refrigerant. This primary subcooled liquid refrigerant then flows through a corresponding heating-direction check valve to drive module 700, where it exchanges heat with the drive module 700 to form a secondary subcooled liquid refrigerant.

[0047] The secondary subcooled liquid refrigerant is divided into a first-stage refrigerant and a second-stage refrigerant. The first-stage refrigerant flows through the main channel of the economizer 200 and exchanges heat with the second-stage refrigerant in the auxiliary channel of the economizer 200, forming a tertiary subcooled liquid refrigerant. After being throttled and depressurized by the first electronic expansion valve 250, the tertiary subcooled liquid refrigerant enters the finned heat exchanger 500 through the corresponding heating flow one-way valve. In the finned heat exchanger 500, it absorbs heat from the ambient air and evaporates. Then, it returns to the suction port of the compressor 100 through the four-way valve and the gas-liquid separator, forming the main heating cycle.

[0048] The second refrigerant is throttled by the second electronic expansion valve 230 to form a medium-temperature, medium-pressure refrigerant, which then enters the auxiliary channel of the economizer 200 to absorb heat from the first refrigerant. After heat exchange, the second refrigerant forms a medium-temperature, medium-pressure gaseous refrigerant, which enters the medium-pressure chamber of the compressor 100 through the gas injection port 120, forming a heating gas injection cycle. This gas injection cycle increases the refrigerant mass flow rate of the compressor 100 and also cools the compressor 100.

[0049] In cooling mode, the high-temperature, high-pressure gaseous refrigerant discharged from compressor 100 passes through an oil separator and a four-way valve before entering finned heat exchanger 500. Finned heat exchanger 500 acts as a condensing heat exchanger, where the refrigerant releases heat to the ambient air and condenses, forming a primary subcooled liquid refrigerant. This primary subcooled liquid refrigerant then flows through a corresponding refrigeration flow direction check valve to drive module 700, forming a secondary subcooled liquid refrigerant.

[0050] The first stream of refrigerant in the secondary subcooled liquid refrigerant forms a tertiary subcooled liquid refrigerant in the main channel of the economizer 200. It then throttles through the first electronic expansion valve 250 and enters the plate heat exchanger 600 through a corresponding refrigeration flow direction check valve. The plate heat exchanger 600 acts as an evaporative heat exchanger, where the refrigerant absorbs heat from the water side and evaporates. It then returns to the suction port of the compressor 100 through a four-way valve and a gas-liquid separator, forming the main refrigeration cycle. The second stream of refrigerant again enters the makeup gas port 120 through the second electronic expansion valve 230 and the auxiliary channel of the economizer 200, forming a refrigeration makeup gas cycle.

[0051] Based on the heating and cooling cycles, the condensed refrigerant first forms a primary subcooling at the outlet of the condenser heat exchanger, then forms a secondary subcooling through heat exchange via the drive module 700, and finally forms a tertiary subcooling through heat exchange between the main and auxiliary channels of the economizer 200. This tertiary subcooling increases the subcooling degree of the liquid refrigerant entering the main cycle and increases the effective enthalpy difference of the refrigerant cycle. Simultaneously, the second refrigerant in the auxiliary channel of the economizer 200 receives the heat required to form a medium-temperature, medium-pressure gaseous refrigerant, thus enabling the tertiary subcooling and enthalpy increase through gas replenishment to occur synergistically.

[0052] Reference Figure 2As shown, the working mechanism of the three-stage subcooling to improve the heating capacity of the unit is further explained.

[0053] Figure 2 Plot pressure P on the ordinate and specific enthalpy h on the abscissa. Taking heating mode as an example, point A represents the state of the high-temperature, high-pressure gaseous refrigerant discharged from compressor 100 when it enters the condensation and heat release process; point C represents the state of the high-pressure liquid refrigerant before the three-stage subcooling; and point B represents the state of the high-pressure liquid refrigerant after sequentially undergoing the first, second, and third stages of subcooling. Points B and C are under the same or approximately the same condensing pressure, and point B is located to the left of point C; therefore, the specific enthalpy at point B is... Enthalpy less than point C .

[0054] Specifically, the high-temperature, high-pressure gaseous refrigerant discharged from compressor 100 enters plate heat exchanger 600 via oil separator and four-way valve. In plate heat exchanger 600, it releases heat to the water side, condenses, and forms primary subcooled liquid refrigerant. The primary subcooled liquid refrigerant flows through drive module 700, exchanges heat with drive module 700, and forms secondary subcooled liquid refrigerant. The first path of the secondary subcooled liquid refrigerant enters the main channel of economizer 200 and exchanges heat with the second path of refrigerant in the auxiliary channel of economizer 200, forming tertiary subcooled liquid refrigerant. Thus, the state point of the high-pressure liquid refrigerant changes from... Figure 2 Point C, as shown, moves to the left to point B.

[0055] Let the mass flow rate of the refrigerant be m, and the specific enthalpy of points A, B, and C be respectively... , and Without three-stage subcooling, the theoretical heating capacity Q0 of the unit can be expressed as: .

[0056] After three stages of subcooling, the unit's theoretical heating capacity It can be represented as: .

[0057] because ,therefore: .

[0058] Where specific enthalpy is expressed in kJ / kg and mass flow rate (m) in kg / s, the heating capacity is expressed in kW. From the above relationships, it can be seen that under the conditions of compressor discharge at 100°C and refrigerant mass flow rate being the same or approximately the same, the third-stage subcooling reduces the specific enthalpy of the high-pressure liquid refrigerant before throttling, thus reducing the heating enthalpy difference of the unit from... Increase to This increases the unit's theoretical heating capacity.

[0059] Meanwhile, during the process of forming a three-stage subcooled liquid refrigerant, the first refrigerant in the main channel of the economizer 200 releases heat to the second refrigerant in the auxiliary channel of the economizer 200. This causes the second refrigerant to exchange heat and form a medium-temperature, medium-pressure gaseous refrigerant, which then enters the medium-pressure chamber of the compressor 100 through the gas injection port 120. Thus, the three-stage subcooling and vapor injection enthalpy enhancement can proceed synergistically, improving the subcooling of the main cycle liquid refrigerant while establishing a gas injection cycle, which is beneficial for balancing the unit's heating capacity and operational efficiency.

[0060] Reference Figure 3 As shown, the present invention also provides a cold shield control method for an air source heat pump, which is applied to an air source heat pump, and the control method can be executed by a controller; Step S101: Determine whether to enter the cold shield start control. When the controller detects that the compressor 100 has switched from the stop state to the start state, it initializes the heat exchange state of the economizer 200 to the state where the preset heat exchange has not been reached, and allows the control of the liquid injection circuit 300 according to the compressor core temperature.

[0061] In a preferred embodiment, when the ambient temperature is lower than a preset ambient temperature threshold and the outlet water temperature is higher than a preset outlet water temperature threshold, the cold shield start control is activated to protect the compressor 100 under low ambient temperature, high water temperature and high compression ratio conditions.

[0062] The preset ambient temperature threshold and preset outlet water temperature threshold can be calibrated according to the design operating range of the air source heat pump and the allowable compression ratio of the compressor 100. If no operating condition activation condition is set, the cold shield start control can also be executed every time the compressor 100 is started from a stopped state. Regardless of the activation method, the exit of the liquid injection circuit 300 is based on the actual heat exchange state of the economizer 200, rather than solely on the fixed start-up duration.

[0063] Step S102: Obtain startup phase detection data. The controller acquires... , and And can be obtained simultaneously , , and . As direct temperature feedback for the opening and closing control of the liquid injection circuit 300; and Used to determine the heat exchange status of Economizer 200; It can continue to be used for conventional exhaust protection of air source heat pumps, but not during the initial start-up phase. Alternative .

[0064] Step S103: Determine the heat exchange status of the economizer 200. The controller determines this based on... and Determine the temperature difference of the economizer by 200. In one embodiment, If the sensor mounting orientation and temperature change direction are predetermined, it is also possible to... Defined as and The signed difference is calculated, and a preset temperature difference threshold is set accordingly. As long as the temperature difference definition used can be adjusted to achieve effective heat exchange with the economizer 200. This can be used in this embodiment.

[0065] when Less than or equal to When the controller determines that the economizer 200 has not reached the preset heat exchange state, it indicates that the main cycle refrigerant has not flowed sufficiently through the economizer 200, or that heat exchange meeting the vapor injection enthalpy requirements has not yet been achieved between the main and auxiliary channels of the economizer 200. Greater than When the controller determines that the economizer 200 has reached the preset heat exchange state, it locks the state until the compressor 100 finishes running, so as to avoid re-entering the liquid injection stage when the refrigerant flow fluctuates for a short time.

[0066] Step S104: When the economizer 200 has not reached the preset heat exchange state, according to Selectively activate the liquid spray circuit 300. Assume the first temperature threshold is... The second temperature threshold is ,and Greater than .when Greater than When, the controller controls the solenoid valve 310 to open; when Less than When the controller closes solenoid valve 310, the controller closes the solenoid valve. In and During this period, maintain the current open / closed state of solenoid valve 310.

[0067] It can be calibrated based on the allowable temperature of the compressor 100 refrigeration oil, the material of the scroll plate, and the installation position of the core temperature sensor 110. Available The result is obtained by subtracting the preset hysteresis from the base value. and It does not need to be limited to a fixed specific value, as long as the liquid injection circuit 300 can be opened when the internal temperature of the compressor 100 reaches the required cooling level, and stably closed after cooling. and The formation of hysteresis can avoid Solenoid valve 310 frequently opens and closes when fluctuating around a single threshold.

[0068] After the solenoid valve 310 opens, the secondary subcooled liquid refrigerant upstream of the main channel inlet of the economizer 200 enters the liquid injection circuit 300 and flows to the compressor 100's gas injection port 120 after being throttled by the capillary tube or the third electronic expansion valve. Because the liquid injection circuit 300 can draw liquid from the upstream liquid refrigerant line before the economizer 200 establishes a stable gas supply, it can provide cooling refrigerant to the compressor 100 earlier than the conventional economizer 200 gas supply. The throttled refrigerant enters the intermediate pressure chamber of the compressor 100 and vaporizes, absorbing heat and directly reducing the temperature of the core region and the scroll compressor 100 structure.

[0069] During the aforementioned startup phase, It may still be affected by low ambient temperature, exhaust pipe heat capacity, compressor 100 housing, and heat absorption by the refrigerant oil. The controller directly relies on... The spray circuit 300 is opened and closed, eliminating the need for waiting time during spraying. Rising to the normal protection threshold, thereby enabling The protection mechanism is activated before the internal thermal state of the compressor 100 is fully reflected.

[0070] Step S105: Switch from liquid spray cooling control to jet enthalpy enhancement control. When Greater than At this time, the controller closes the solenoid valve 310 and prevents it from reopening during this operation, while simultaneously putting the second electronic expansion valve 230 into the gas replenishment control state. The secondary subcooled liquid refrigerant flows through the auxiliary channel of the economizer 200 after being throttled by the second electronic expansion valve 230, where it exchanges heat to form a medium-temperature, medium-pressure gaseous refrigerant, which then enters the medium-pressure chamber of the compressor 100 through the gas replenishment port 120.

[0071] Therefore, when the economizer 200 has not reached the preset heat exchange state, the liquid injection circuit 300 operates according to... Liquid refrigerant is intermittently supplied for cooling; after the economizer 200 reaches the preset heat exchange state, the gas supply circuit 400 continuously supplies medium-temperature, medium-pressure gaseous refrigerant, and the gas supply volume is controlled and regulated by the intermediate pressure. The liquid injection circuit 300 and the gas supply circuit 400 are sequentially connected in time, forming a cold shield protection process from the start of liquid injection to stable gas injection.

[0072] Step S106: Execute intermediate pressure closed-loop control. After entering the jet enthalpy enhancement control, the controller obtains the intermediate pressure according to the preset control cycle. , and . and The same pressure reference is used; when calculating using the following geometric mean relationship, absolute pressure is preferred.

[0073] Controller according to and Determine the target intermediate pressure The calculation relationship is as follows The target intermediate pressure varies with the operating conditions of the air source heat pump's condenser and evaporator sides, and is used to characterize the optimal make-up gas pressure under current high and low pressure conditions.

[0074] The controller further determines the pressure deviation. , Let the preset pressure deviation threshold be... , It is a positive value. When Greater than When, it indicates If the value exceeds the target range, the controller reduces the opening of the second electronic expansion valve 230; when... Less than When, it indicates If the value is below the target range, the controller increases the opening of the second electronic expansion valve 230; when... Less than or equal to ,and Less than or equal to At this time, the controller maintains the current opening of the second electronic expansion valve 230.

[0075] A dead zone for intermediate pressure regulation is formed, which can be calibrated based on the detection accuracy of the pressure sensor, the minimum adjustment step size of the second electronic expansion valve 230, and the allowable intermediate pressure fluctuation range. Reducing the opening of the second electronic expansion valve 230 will reduce the refrigerant flow into the auxiliary channel of the economizer 200 and the refrigerant injection port 120 of the compressor 100, thus... Lowering; increasing the opening of the second electronic expansion valve 230 will increase the air supply, making Increase. Through the aforementioned directional adjustments, it is possible to... Approaching gradually .

[0076] In another embodiment, the controller uses proportional-integral-derivative control to regulate the second electronic expansion valve 230.

[0077] Step S107: Execute intermediate pressure limit protection. Set the preset intermediate pressure limit value to... The preset protection margin is .when Greater than - Even at that time Not yet reached The controller also pre-reduces the opening of the second electronic expansion valve 230 to reduce the amount of supplementary air and suppress [the flow of air]. It continues to rise.

[0078] If the opening of the second electronic expansion valve 230 is reduced, after one or more consecutive control cycles, Still greater than - Then the controller further reduces the operating frequency of compressor 100. It can be determined based on the allowable pressure and axial load of the pressure chamber in compressor 100. This is designed to provide a safety margin for sensor errors, pressure fluctuations, and control response time. The tiered control prioritizes adjusting the supplementary gas volume using the second electronic expansion valve 230, and then reduces the compressor frequency 100 if the valve adjustment is insufficient.

[0079] When the controller receives a shutdown command, it closes the solenoid valve 310 of the liquid injection circuit 300 and adjusts the second electronic expansion valve 230 to the shutdown opening or closed state. Simultaneously, it clears the lock flag for the heat exchange state of the economizer 200, and repeats steps S101 to S107 for the next startup. After shutdown, the one-way valve upstream of the gas inlet 120 blocks the refrigerant from flowing away from the gas inlet 120.

[0080] When an air source heat pump is shut down for an extended period, the pressure and temperature within the system gradually reach equilibrium, and liquid refrigerant may migrate into the gas supply line. A one-way valve prevents liquid refrigerant from entering the intermediate-pressure chamber of compressor 100, reducing its accumulation and preventing liquid compression when compressor 100 restarts due to the incompressibility of the liquid refrigerant.

[0081] In one specific embodiment, the above control method is illustrated using a startup process under low ambient temperature and high outlet water temperature conditions. After the compressor 100 starts, the controller sets the economizer 200 to a state where the preset heat exchange state has not been reached, and continuously acquires data. , and At this point, the main cycle refrigerant has not yet established a stable flow within the economizer 200. Not crossed The liquid injection circuit 300 is in an allowable control state.

[0082] As the internal temperature of compressor 100 rises, when Greater than When the solenoid valve 310 opens, the secondary subcooled liquid refrigerant enters the gas injection port 120 after being throttled by the injection circuit 300 and vaporizes, absorbing heat. Reduce to When the following occurs, solenoid valve 310 closes; if economizer 200 still has not reached the preset heat exchange state, subsequent... Greater than again At this time, solenoid valve 310 can be reopened. Thus, during the period before the gas supply to economizer 200 is established, liquid injection protection with temperature hysteresis is formed.

[0083] As the main cycle refrigerant gradually flows through the economizer 200... and The temperature difference between them increases. When Greater than At this time, the controller locks that the economizer 200 has reached the preset heat exchange state, closes and prohibits the liquid injection circuit 300, and the second electronic expansion valve 230 begins to supply refrigerant to the auxiliary channel of the economizer 200. The compressor 100 enters the liquid injection enthalpy increase stage from the liquid injection cooling stage.

[0084] After entering the jet enthalpy enhancement stage, the controller calculates... and The opening of the second electronic expansion valve 230 is adjusted according to dead-zone control or PID control. If... near Then, the second electronic expansion valve 230 and the compressor 100 frequency are sequentially closed for graded protection. In this way, the air source heat pump can continuously obtain compressor 100 protection adapted to the current operating conditions throughout the entire startup and stable operation process.

[0085] The aforementioned cold shield control method can be used in both heating and cooling modes. In heating mode, this method is particularly suitable for operating conditions where low ambient temperature and high outlet water temperature result in a large compression ratio; in cooling mode, this method can be used for operating conditions where high ambient temperature or other conditions increase the internal heat load of compressor 100. When the four-way valve changes the main circulation direction, the gas replenishment circuit 400, the liquid injection circuit 300, and the intermediate pressure control logic can remain unchanged.

[0086] , , , , and All of these parameters can be determined during the product development phase through tests on the allowable temperature and pressure of compressor 100, the heat exchange characteristics of economizer 200, and the overall unit performance, and stored in the controller. Different compressor 100 specifications, refrigerant types, and unit capacities can use different calibration values, but they must meet the following requirements. Greater than , Greater than zero and Greater than zero. This embodiment does not limit the above parameters to a single specific value.

[0087] When the throttling element 320 in the spray circuit 300 is a capillary tube, the spray flow rate can be determined by the length and inner diameter of the capillary tube; when a third electronic expansion valve is used, the flow rate can be determined by the controller based on... The opening degree can be adjusted by other operating parameters during the liquid injection phase. Regardless of whether a capillary tube or a third electronic expansion valve is used, the solenoid valve 310 can be used as a fast opening and closing element of the liquid injection circuit 300, which obtains subcooled liquid refrigerant upstream of the main channel inlet of the economizer 200.

[0088] Economizer 200 temperature difference Both can be adopted and The absolute difference can also be a signed difference defined according to the actual flow direction of the refrigerant. For systems where the main channel flow direction of the economizer 200 is the same in both heating and cooling modes, the same temperature difference definition can be used; for systems where the main channel flow direction of the economizer 200 changes with the mode, the corresponding temperature difference direction can be selected according to the status of the four-way valve.

[0089] The core temperature sensor 110 can be directly installed on the compressor housing 100 at a position corresponding to the core area, or it can be installed at a position where the core area temperature can be calculated through calibration. Compared to the exhaust temperature sensor 130, the core temperature sensor 110 has a shorter thermal response path to the inside of the compressor 100, thus enabling it to reflect the thermal state of the core area more promptly during the startup phase.

[0090] Using the aforementioned system and control methods, when the air replenishment circuit 400 is not established, it can be directly based on... It provides liquid injection cooling, switches to jet enthalpy enhancement after the economizer 200 reaches the preset heat exchange state, and through... , and The three-pressure linkage regulation of the gas supply can reduce the risk of excessively high core temperature, refrigerant oil carbonization, and scroll component lubrication failure during the compressor 100 startup phase. At the same time, intermediate pressure dead zone control, PID control, and limit protection can improve the gas supply regulation accuracy and limit the load on the intermediate pressure chamber of the compressor 100. The three-stage subcooling helps to improve the effective enthalpy difference of the refrigerant cycle and the overall energy efficiency.

[0091] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cooling shield control method for an air source heat pump, applied to an air source heat pump, wherein the air source heat pump is provided with a compressor (100), an economizer (200), a gas supply circuit (400), and a liquid injection circuit (300), characterized in that, Includes the following steps: During the initial start-up phase of the air source heat pump, the core temperature of the compressor (100), the inlet temperature of the main channel of the economizer (200), and the outlet temperature of the main channel of the economizer (200) are obtained; The heat exchange state of the economizer (200) is determined based on the inlet temperature of the main channel of the economizer (200) and the outlet temperature of the main channel of the economizer (200); When the heat exchange state of the economizer (200) indicates that the economizer (200) has not reached the preset heat exchange state, the liquid injection circuit (300) is selectively turned on according to the core temperature of the compressor (100), so that the subcooled liquid refrigerant is injected into the gas supply port (120) of the compressor (100) through the liquid injection circuit (300) to reduce the core temperature of the compressor (100); When the heat exchange state of the economizer (200) indicates that the economizer (200) has reached the preset heat exchange state, the liquid injection circuit (300) is controlled to close, and the gas replenishment circuit (400) is controlled to deliver the medium-temperature and medium-pressure gaseous refrigerant formed by the heat exchange of the economizer (200) to the gas replenishment port (120), so as to switch the compressor (100) from liquid injection cooling control to gas injection enthalpy increase control; During the jet enthalpy control process, the condensing pressure, evaporating pressure and intermediate pressure of the air source heat pump are obtained, the target intermediate pressure is determined based on the condensing pressure and the evaporating pressure, and the amount of gas supplied to the gas supply circuit (400) is adjusted based on the pressure deviation of the intermediate pressure relative to the target intermediate pressure.

2. The air source heat pump cooling shield control method according to claim 1, characterized in that, The step of determining the heat exchange state of the economizer (200) based on the inlet temperature of the main channel and the outlet temperature of the main channel of the economizer (200) includes: Determine the temperature difference of the economizer (200) between the inlet temperature of the main channel of the economizer (200) and the outlet temperature of the main channel of the economizer (200); When the temperature difference of the economizer (200) is greater than the preset temperature difference threshold, it is determined that the economizer (200) has reached the preset heat exchange state.

3. The air source heat pump cooling shield control method according to claim 1, characterized in that, The selective activation of the injection circuit (300) based on the core temperature of the compressor (100) includes: When the core temperature of the compressor (100) is greater than the first temperature threshold, the liquid injection circuit (300) is controlled to be turned on; When the core temperature of the compressor (100) is less than the second temperature threshold, the liquid injection circuit (300) is controlled to close. Wherein, the second temperature threshold is less than the first temperature threshold, and when the core temperature of the compressor (100) is between the second temperature threshold and the first temperature threshold, the current open / closed state of the injection circuit (300) is maintained.

4. The air source heat pump cooling shield control method according to claim 3, characterized in that, The inlet of the liquid injection circuit (300) is connected to the subcooled liquid refrigerant pipeline upstream of the main channel inlet of the economizer (200), and the outlet of the liquid injection circuit (300) is connected to the gas supply port (120) of the compressor (100). The liquid injection circuit (300) is equipped with a solenoid valve (310) and a throttling element (320). The selective activation of the liquid injection circuit (300) based on the core temperature of the compressor (100) includes controlling the opening or closing of the solenoid valve (310) so that the subcooled liquid refrigerant is injected into the gas inlet (120) after being throttled by the throttling element (320).

5. The air source heat pump cooling shield control method according to claim 1, characterized in that, Determining the target intermediate pressure based on the condensation pressure and the evaporation pressure includes: determining the square root of the product of the condensation pressure and the evaporation pressure as the target intermediate pressure.

6. The air source heat pump cooling shield control method according to claim 1, characterized in that, The step of adjusting the air supply amount of the air supply circuit (400) based on the pressure deviation between the intermediate pressure and the target intermediate pressure includes: The difference between the intermediate pressure and the target intermediate pressure is defined as the pressure deviation; When the pressure deviation is greater than the preset pressure deviation threshold, the opening of the second electronic expansion valve (230) in the air replenishment circuit (400) is reduced; When the pressure deviation is less than the negative value of the preset pressure deviation threshold, the opening of the second electronic expansion valve (230) is increased; When the pressure deviation is between the negative value of the preset pressure deviation threshold and the preset pressure deviation threshold, the current opening of the second electronic expansion valve (230) is maintained.

7. The air source heat pump cooling shield control method according to claim 5, characterized in that, The step of adjusting the amount of air replenishment in the air replenishment circuit (400) according to the pressure deviation between the intermediate pressure and the target intermediate pressure includes: using the difference between the intermediate pressure and the target intermediate pressure as the input of proportional-integral-derivative control, and adjusting the opening of the second electronic expansion valve (230) in the air replenishment circuit (400) according to the output of the proportional-integral-derivative control.

8. The air source heat pump cooling shield control method according to claim 6, characterized in that, Also includes: When the intermediate pressure is greater than the difference between the preset intermediate pressure limit and the preset protection margin, the opening of the second electronic expansion valve (230) is reduced; When the opening of the second electronic expansion valve (230) is reduced, if the intermediate pressure is still greater than the difference between the preset intermediate pressure limit and the preset protection margin, the operating frequency of the compressor (100) is reduced.

9. The air source heat pump cooling shield control method according to claim 4, characterized in that, A one-way valve is provided upstream of the air inlet (120) of the compressor (100) to allow refrigerant to flow toward the air inlet (120) only, and the one-way valve prevents liquid refrigerant from flowing back to the medium pressure chamber of the compressor (100) when the air source heat pump stops.

10. An air-source heat pump cooling shield control system, characterized in that, include: The compressor (100) is equipped with an air inlet (120). The economizer (200) has a main channel and an auxiliary channel for mutual heat exchange; The gas replenishment circuit (400) has an inlet connected to the subcooled liquid refrigerant pipeline upstream of the main channel inlet of the economizer (200), and an outlet connected to the gas replenishment port (120). The second electronic expansion valve (230) and the auxiliary channel are sequentially arranged in the gas replenishment circuit (400) along the refrigerant flow direction. The liquid injection circuit (300) has an inlet connected to the subcooled liquid refrigerant pipeline and an outlet connected to the gas supply port (120). The liquid injection circuit (300) is equipped with a solenoid valve (310) and a throttling element (320). Temperature detection components include a core temperature sensor (110), an economizer main channel inlet temperature sensor (210), and an economizer main channel outlet temperature sensor (220). The pressure sensing assembly includes a condensation pressure sensor (260), an evaporation pressure sensor (270), and an intermediate pressure sensor (240). The controller is electrically connected to the second electronic expansion valve (230), the solenoid valve (310), the temperature detection component, and the pressure detection component, respectively. During the initial start-up phase of the compressor (100), the controller determines the heat exchange state of the economizer (200) based on the inlet temperature of the main channel of the economizer (200) and the outlet temperature of the main channel of the economizer (200); When the heat exchange state of the economizer (200) indicates that the economizer (200) has not reached the preset heat exchange state, the solenoid valve (310) is opened or closed according to the core temperature of the compressor (100) so that the subcooled liquid refrigerant is selectively injected into the gas inlet (120) after being throttled by the throttling element (320). When the heat exchange state of the economizer (200) indicates that the economizer (200) has reached the preset heat exchange state, the opening of the solenoid valve (310) is prohibited, and the second electronic expansion valve (230) is controlled so that the medium-temperature and medium-pressure gaseous refrigerant formed by the heat exchange of the auxiliary channel is delivered to the gas supply port (120). During the vapor injection enthalpy control process, the condensation pressure, the evaporation pressure, and the intermediate pressure are acquired. The target intermediate pressure is determined based on the condensation pressure and the evaporation pressure. The opening of the second electronic expansion valve (230) is adjusted based on the pressure deviation of the intermediate pressure relative to the target intermediate pressure.

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