A heat pump air conditioning system capable of defrosting and a pure electric light truck

Abstract

The present invention discloses a heat pump air conditioning system capable of defrosting and a pure electric light truck, the heat pump air conditioning system comprising a compressor, a four-way valve, an indoor evaporator, an outdoor condenser, a first expansion valve, a liquid storage device, a three-way valve, a defrosting solenoid valve, an outdoor evaporator, an air supply device, a second expansion valve and a controller; the fifth valve port and the sixth valve port of the three-way valve are connected to the fluid path between the fourth valve port and the indoor evaporator, the seventh valve port is connected to one end of the outdoor evaporator through the defrosting solenoid valve, and the other end of the outdoor evaporator is connected to the fluid path between the first expansion valve and the liquid storage device through the second expansion valve; the outdoor evaporator is arranged at an adjacent position to the outdoor condenser, the air supply device is electrically connected to the controller, and the air supply device can supply air to the outdoor condenser via the outdoor evaporator. The heat pump air conditioning system disclosed by the present invention has high defrosting efficiency, is energy-saving and environmentally friendly, and is helpful to enhance the heating capacity and prolong the heating time.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile heat pump air conditioning, and in particular to a heat pump air conditioning system capable of defrosting and a pure electric light truck. Background Art

[0002] With the shortage of energy and the rise in oil prices, new energy vehicles are increasingly favored by consumers, but the range of new energy vehicles is also one of the problems that need to be solved urgently. Unlike traditional fuel vehicles, new energy vehicles require power batteries for cooling in summer and heating in winter. At present, most pure electric vehicles on the market are equipped with two separate systems for air conditioning and heating. When the air conditioning is turned on for cooling in summer and the heating is turned on for heating in winter, the range of new energy vehicles will be reduced by about 30%. The heat pump system integrates the air conditioning system and the heating system into one system. Compared with the PTC heating method, the heat pump air conditioning system has a high energy efficiency ratio. Under the ambient condition of -5℃, the COP (energy conversion efficiency ratio) of the PTC heating system is about 1, while the COP of the heat pump air conditioning system reaches more than 2. The heat pump air conditioning system has great advantages in energy saving. However, due to the fact that the current technology is not fully mature, the heat pump air conditioning system still has certain defects.

[0003] In the heating mode, the working environment of the heat pump air conditioning system is generally below 0℃. If the outdoor environment temperature is low and the humidity is high, it is very easy to cause frost or even ice on the surface of the outdoor condenser. If the outdoor condenser cannot be defrosted in time and quickly, it will seriously affect the heating performance of the system and greatly increase the energy consumption of the system. At present, there are two commonly used defrosting methods: reverse cycle defrosting method and hot gas bypass defrosting method. The reverse defrosting method uses the reverse Carnot cycle to achieve the purpose of defrosting, but the mechanical impact is large, and the cooling mode needs to be turned on many times for defrosting, and a large amount of heat is continuously absorbed from the cab, and the temperature in the car fluctuates greatly. After the defrosting is completed, it switches to the heating mode, which will generate a large amount of water vapor in the air conditioning box. The water vapor will quickly frost and ice on the cab glass along the air duct to the cab, blocking the driving field of vision and causing driving safety hazards; hot gas bypass defrosting relies on the heat storage and power consumption of the compressor to provide defrosting heat. Due to the attenuation of the suction temperature, the compressor input power, and the small suction and exhaust pressure difference, the exhaust temperature will continue to drop during the melting stage of the frost layer, making the bypass defrosting insufficient and the defrosting speed significantly reduced. In addition, in the existing defrosting methods, the basis for judging frost is not scientific. Defrosting is often controlled only after the frost has become very thick, which inevitably makes defrosting difficult and takes a long time, causing adverse effects on the heating effect. If defrosting is started when there is little frost, it will consume more energy, put a heavy burden on the heat pump air-conditioning system, and is not conducive to energy saving and heat pump system maintenance. Summary of the invention

[0004] The present invention provides a heat pump air conditioning system capable of defrosting and a pure electric light truck to solve at least one of the above-mentioned technical problems.

[0005] The technical solution adopted by the present invention is:

[0006] A heat pump air-conditioning system capable of defrosting, the heat pump air-conditioning system having a cooling mode, a heating mode and a defrosting mode, the heat pump air-conditioning system comprising a compressor, a four-way valve, an indoor evaporator, an outdoor condenser, a first expansion valve and a liquid storage device; the compressor has an exhaust port and an air return port; the four-way valve has a first valve port, a second valve port, a third valve port and a fourth valve port, the first valve port is connected to the exhaust port, the second valve port is connected to the air return port, the third valve port and the fourth valve port are selectively connected to the first valve port, and when one of the third valve port and the fourth valve port is connected to the first valve port, the other is connected to the second valve port; one end of the indoor evaporator is connected to the fourth valve port, and the other end is connected to the liquid storage device through the first expansion valve; one end of the outdoor condenser One end is connected with the third valve port, and the other end is connected with the liquid storage device; the heat pump air-conditioning system also includes a three-way valve, a defrost solenoid valve, an outdoor evaporator, an air supply device, a second expansion valve and a controller; the three-way valve has a fifth valve port, a sixth valve port and a seventh valve port, the fifth valve port and the sixth valve port are connected to the fluid path between the fourth valve port and the indoor evaporator, the seventh valve port is connected to one end of the outdoor evaporator through the defrost solenoid valve, and the other end of the outdoor evaporator is connected to the fluid path between the first expansion valve and the liquid storage device through the second expansion valve; the outdoor evaporator is arranged at a position adjacent to the outdoor condenser, the air supply device is electrically connected to the controller, and the air supply device can supply air toward the outdoor condenser via the outdoor evaporator.

[0007] The heat pump air conditioning system capable of defrosting in the present invention also has the following additional technical features:

[0008] The heat pump air conditioning system also includes a first temperature sensor, a second temperature sensor, a wind speed sensor and a relative humidity sensor, wherein the first temperature sensor is used to detect the outdoor ambient temperature, the second temperature sensor is used to detect the surface temperature of the outdoor condenser, the wind speed sensor is used to detect the headwind speed on the surface of the outdoor condenser, and the relative humidity sensor is used to detect the relative humidity of the outdoor environment. The first temperature sensor, the second temperature sensor, the wind speed sensor and the relative humidity sensor are all electrically connected to the controller to control the power on and off of the defrost solenoid valve through the controller; when the heat pump air conditioning system is in a heating mode, the first temperature sensor, the second temperature sensor, the wind speed sensor and the relative humidity sensor respectively transmit outdoor ambient temperature information, surface temperature information of the outdoor condenser, headwind speed information on the surface of the outdoor condenser and outdoor ambient relative humidity information to the controller, and the controller can power on the defrost solenoid valve according to the outdoor ambient temperature information, the surface temperature information, the headwind speed information and the outdoor ambient relative humidity information so that the heating mode and the defrost mode of the heat pump air conditioning system are in parallel.

[0009] When the surface temperature detected by the second temperature sensor is less than the first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than the second threshold, the headwind speed detected by the wind speed sensor is less than the third threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than the fourth threshold, the heat pump air-conditioning system enters the first defrost mode, the defrost solenoid valve is energized to connect the seventh valve port with the outdoor evaporator, and the air supply device remains closed; when the surface temperature detected by the second temperature sensor is less than the first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than the second threshold, the headwind speed detected by the wind speed sensor is less than the fifth threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than the sixth threshold, the heat pump air-conditioning system enters the second defrost mode, the defrost solenoid valve is energized to connect the seventh valve port with the outdoor evaporator, the controller controls the air supply device to open and supply air to the outdoor evaporator, the airflow is heated by the outdoor evaporator and then flows to the outdoor condenser as hot air, the fifth threshold is less than the third threshold, and the sixth threshold is greater than the fourth threshold.

[0010] When the surface temperature detected by the second temperature sensor is less than a first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a third threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a fourth threshold for a first preset time period, the heat pump air-conditioning system enters the first defrost mode; when the surface temperature detected by the second temperature sensor is less than a first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a fifth threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a sixth threshold for a second preset time period, the heat pump air-conditioning system enters the second defrost mode.

[0011] In either the first defrost mode or the second defrost mode, when the surface temperature of the outdoor condenser detected by the second temperature sensor is higher than the seventh threshold for a third preset time period, the defrost solenoid valve is powered off.

[0012] The heat pump air conditioning system also includes a third temperature sensor electrically connected to the controller, and the third temperature sensor is used to detect the indoor ambient temperature; when the temperature difference measured by the second temperature sensor and the third temperature sensor is less than the eighth threshold for a fourth preset time period, the defrost solenoid valve is powered off.

[0013] In the first defrost mode, the operating frequency of the compressor is a first preset frequency; in the second defrost mode, the operating frequency of the compressor is a second preset frequency, and the second preset frequency is greater than the first preset frequency.

[0014] The opening degree of the first expansion valve and / or the opening degree of the second expansion valve is adjustable.

[0015] The air supply device can supply air in different directions.

[0016] A pure electric light truck provided by the present invention includes a heat pump air conditioning system, wherein the heat pump air conditioning system is the heat pump air conditioning system capable of defrosting as described above.

[0017] Due to the adoption of the above technical solution, the technical effects achieved by the present invention are as follows:

[0018] The heat pump air-conditioning system capable of defrosting provided by the present invention has three working modes: cooling mode, heating mode, and defrost mode, and the heating mode and the defrost mode can be started in parallel. In the defrost mode, the compressor does not stop, the four-way valve does not reverse, and there is no need to switch to the cooling mode. Under the premise of sustainable heating to the vehicle, the frost on the surface of the outdoor condenser is effectively removed, which helps to enhance the heating capacity of the heat pump air-conditioning system, extend the heating time, and improve the cycle performance coefficient COP. In addition, it also effectively solves the technical problems of intermittent heating by the reverse defrost method, frost on the cab glass affecting the driving field of view, and insufficient heat and incomplete defrosting by the hot air bypass method. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 A schematic diagram of a flow path of a heat pump air conditioning system in a defrost mode provided by an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the flow path of the heat pump air conditioning system in the heating mode provided by an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of the flow path of the heat pump air-conditioning system in cooling mode provided by an embodiment of the present invention.

[0023] Reference numerals:

[0024] 1 compressor, 2 four-way valve, 3 indoor evaporator, 4 outdoor condenser, 5 first expansion valve, 6 liquid storage device, 7 three-way valve, 8 defrost solenoid valve, 9 outdoor evaporator, 10 air supply device, 11 second expansion valve. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below in an exemplary manner in conjunction with the accompanying drawings.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, the first feature "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0029] In the embodiment of the present invention, a heat pump air conditioning system and a pure electric light truck capable of defrosting are provided. For the convenience of explanation and understanding, the following contents provided by the present invention are all described based on the illustrated product structure. Of course, those skilled in the art can understand that the above structure is only used as a specific example and schematic description, and cannot constitute a specific limitation on the technical solution provided by the present invention.

[0030] like Figure 1As shown, a heat pump air-conditioning system capable of defrosting, the heat pump air-conditioning system comprises a compressor 1, a four-way valve 2, an indoor evaporator 3, an outdoor condenser 4, a first expansion valve 5 and a liquid storage device 6; the compressor 1 has an exhaust port and an air return port; the four-way valve 2 has a first valve port, a second valve port, a third valve port and a fourth valve port, the first valve port is connected to the exhaust port, the second valve port is connected to the air return port, the third valve port and the fourth valve port are selectively connected to the first valve port, and when one of the third valve port and the fourth valve port is connected to the first valve port, the other is connected to the second valve port; one end of the indoor evaporator 3 is connected to the fourth valve port, and the other end is connected to the liquid storage device 6 through the first expansion valve 5; one end of the outdoor condenser 4 is connected to the third valve port, and the other end is connected to the The heat pump air conditioning system further comprises a three-way valve 7, a defrost solenoid valve 8, an outdoor evaporator 9, an air supply device 10, a second expansion valve 11 and a controller; the three-way valve 7 has a fifth valve port, a sixth valve port and a seventh valve port, the fifth valve port and the sixth valve port are connected to the fluid path between the fourth valve port and the indoor evaporator 3, the seventh valve port is connected to one end of the outdoor evaporator 9 through the defrost solenoid valve 8, and the other end of the outdoor evaporator 9 is connected to the fluid path between the first expansion valve 5 and the liquid storage device 6 through the second expansion valve 11; the outdoor evaporator 9 is arranged at a position adjacent to the outdoor condenser 4, the air supply device 10 is electrically connected to the controller, and the air supply device 10 can supply air toward the outdoor condenser 4 via the outdoor evaporator 9.

[0031] The heat pump air-conditioning system capable of defrosting provided by the present invention has three working modes: cooling mode, heating mode and defrosting mode.

[0032] In cooling mode, if Figure 3 As shown, the first valve port of the four-way valve 2 is connected to the third valve port, and the second valve port is connected to the fourth valve port. The high-temperature and high-pressure refrigerant gas flows from the exhaust port of the compressor 1 into the first valve port of the four-way valve 2, and then flows into the outdoor condenser 4 from the third valve port of the four-way valve 2, condenses into liquid refrigerant in the outdoor condenser 4, and then the liquid refrigerant enters the liquid storage device 6. The low-temperature and low-pressure liquid refrigerant in the liquid storage device 6 enters the indoor evaporator 3 through the first expansion valve 5 and evaporates into gas, and absorbs heat during the evaporation process to form a refrigeration effect. The refrigerant vapor formed in the indoor evaporator 3 then enters through the fourth valve port of the four-way valve 2, and flows out from the second valve port, and finally returns to the compressor 1 through the return port of the compressor 1 to complete the refrigeration cycle. In this refrigeration mode, the defrost solenoid valve 8 is powered off, the three-way valve 7 and the outdoor evaporator 9 are not connected, and the defrost mode does not operate.

[0033] In heating mode, if Figure 2As shown, the first valve port of the four-way valve 2 is connected to the fourth valve port, and the second valve port is connected to the third valve port. The high-temperature and high-pressure refrigerant gas flows from the exhaust port of the compressor 1 into the first valve port of the four-way valve 2, and then flows into the indoor evaporator 3 from the fourth valve port of the four-way valve 2. It condenses into liquid refrigerant in the indoor evaporator 3 and releases heat to achieve the indoor heating effect. The condensed liquid refrigerant enters the liquid storage device 6 through the first expansion valve 5, and then enters the outdoor condenser 4 to absorb external heat and evaporate. The evaporated steam enters the four-way valve 2 through the third valve port, and flows out from the second valve port, and finally returns to the compressor 1 through the return port of the compressor 1 to complete the heating cycle. In this heating mode, the defrost solenoid valve 8 can be kept off so that the heat pump air conditioning system only runs the heating mode. At this time, the three-way valve 7 and the outdoor evaporator 9 are not connected, and the defrost mode is not running; in this heating mode, the defrost solenoid valve 8 can also be powered on so that the heat pump air conditioning system runs the heating mode and the defrost mode at the same time.

[0034] In defrost mode, Figure 1 As shown, the first valve port of the four-way valve 2 is connected with the fourth valve port, the second valve port is connected with the third valve port, the defrost solenoid valve 8 is energized, the three-way valve 7 is connected with the outdoor evaporator 9, and the high-temperature and high-pressure refrigerant gas flows from the exhaust port of the compressor 1 into the first valve port of the four-way valve 2 and flows out from the fourth valve port. A part of the refrigerant gas flowing out from the fourth valve port enters the indoor evaporator 3 to complete the heating cycle, and the other part of the refrigerant gas flows to the outdoor evaporator 9 through the seventh valve port of the three-way valve 7 and the defrost solenoid valve 8. The refrigerant gas condenses in the outdoor evaporator 9 and releases heat. The heat is dispersed on the surface of the outdoor evaporator 9 and the surrounding air, and is discharged through the outdoor evaporator through the air supply device 10. 9 supplies air toward the outdoor condenser 4, and the airflow drives the heat of the surrounding air on the surface of the outdoor evaporator 9 to flow to the outdoor condenser 4, melting the frost on the surface of the outdoor condenser 4, and the liquid refrigerant formed by the condensation of the high-temperature and high-pressure refrigerant gas in the outdoor evaporator 9 flows into the fluid path between the first expansion valve 5 and the liquid storage device 6 through the second expansion valve 11, and flows into the liquid storage device 6 together with the liquid refrigerant discharged from the indoor evaporator 3, and then enters the outdoor condenser 4 to absorb external heat and evaporate, and the evaporated steam enters the four-way valve 2 through the third valve port, and flows out from the second valve port, and finally returns to the compressor 1 through the return air port of the compressor 1, completing the heating cycle and the defrosting cycle.

[0035] The heating mode and the defrost mode can be started in parallel. In the defrost mode, the compressor 1 does not stop, the four-way valve 2 does not reverse, and there is no need to switch to the cooling mode. Under the premise of sustainable heating to the vehicle, the frost on the surface of the outdoor condenser 4 can be effectively removed, which helps to enhance the heating capacity of the heat pump air-conditioning system, extend the heating time, and improve the cycle performance coefficient COP. In addition, it also effectively solves the technical problems of intermittent heating by the reverse defrost method, frost on the cab glass affecting the driving field of vision, and insufficient heat and incomplete defrosting by the hot air bypass method.

[0036] It should be noted that in the cooling mode, the low-temperature and low-pressure liquid refrigerant in the liquid storage device 6 enters the indoor evaporator 3 through the first expansion valve 5 to evaporate into gas. In the heating mode and the defrost mode, the condensed liquid refrigerant enters the liquid storage device 6 through the first expansion valve 5. Therefore, the first expansion valve 5 is preferably a two-way expansion valve, and the second expansion valve 11 is preferably a one-way expansion valve.

[0037] As a preferred embodiment of the present invention, the heat pump air-conditioning system also includes a first temperature sensor, a second temperature sensor, a wind speed sensor and a relative humidity sensor, the first temperature sensor is used to detect the outdoor ambient temperature, the second temperature sensor is used to detect the surface temperature of the outdoor condenser 4, the wind speed sensor is used to detect the headwind speed on the surface of the outdoor condenser 4, and the relative humidity sensor is used to detect the relative humidity of the outdoor environment. The first temperature sensor, the second temperature sensor, the wind speed sensor and the relative humidity sensor are all electrically connected to the controller to control the power on and off of the defrost solenoid valve 8 through the controller; when the heat pump air-conditioning system is in heating mode, the first temperature sensor, the second temperature sensor, the wind speed sensor and the relative humidity sensor respectively transmit outdoor ambient temperature information, surface temperature information of the outdoor condenser 4, headwind speed information on the surface of the outdoor condenser 4 and outdoor ambient relative humidity information to the controller, and the controller can power on the defrost solenoid valve 8 according to the outdoor ambient temperature information, surface temperature information, headwind speed information and outdoor ambient relative humidity information so that the heating mode and defrost mode of the heat pump air-conditioning system are parallel.

[0038] Those skilled in the art can understand that whether the outdoor condenser 4 is frosted, the thickness of the frost layer, etc. are closely related to factors such as the outdoor temperature, the surface temperature of the outdoor condenser 4, the headwind speed, and the outdoor relative humidity. Different temperature, humidity, and headwind speeds result in different degrees of frosting and speeds of frosting. The present application uses a first temperature sensor, a second temperature sensor, a wind speed sensor, and a relative humidity sensor to respectively detect four types of information, namely, the outdoor ambient temperature, the surface temperature of the outdoor condenser 4, the headwind speed on the surface of the outdoor condenser 4, and the outdoor ambient relative humidity as the basis for judging whether the defrosting mode is turned on or off. Compared with the existing method of only using the outdoor temperature as the basis for judgment, the defrosting judgment basis of the heat pump air conditioning system provided by the present invention is more scientific and reasonable, which greatly improves the reliability of the defrosting judgment, thereby effectively reducing the probability of false defrosting. In the heating mode, the first temperature sensor, the second temperature sensor, the wind speed sensor and the relative humidity sensor transmit the outdoor ambient temperature information, the surface temperature information of the outdoor condenser 4, the condenser surface headwind speed information of the outdoor condenser 4, and the air relative humidity information to the controller in real time. The controller analyzes and judges the above four kinds of information. When the above four kinds of information meet the conditions required for frosting, the controller energizes the defrost solenoid valve 8, and the heat pump air-conditioning system starts the defrost mode. The heating mode and the defrost mode are operated in parallel.

[0039] As a preferred embodiment, when the surface temperature detected by the second temperature sensor is less than a first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a third threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a fourth threshold, the heat pump air-conditioning system enters a first defrost mode, the defrost solenoid valve 8 is energized to connect the seventh valve port with the outdoor evaporator 9, and the air supply device 10 remains closed; when the surface temperature detected by the second temperature sensor is less than a first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a fifth threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a sixth threshold, the heat pump air-conditioning system enters a second defrost mode, the defrost solenoid valve 8 is energized to connect the seventh valve port with the outdoor evaporator 9, the controller controls the air supply device 10 to open and supply air to the outdoor evaporator 9, and the airflow flows to the outdoor condenser 4 after heat exchange through the outdoor evaporator 9 into hot air, the fifth threshold is less than the third threshold, and the sixth threshold is greater than the fourth threshold.

[0040] Those skilled in the art can understand that, under the variable of temperature, when the surface temperature of the outdoor condenser 4 is lower than 0°C, when the outdoor air flows through the outdoor condenser 4, the moisture contained in the air will precipitate and adhere to the surface of the outdoor condenser 4 to form a frost layer. Therefore, as a preference, the first threshold value can be set to 0°C, that is, under the premise that the surface temperature of the outdoor condenser 4 detected by the second temperature sensor is lower than 0°C, it can be judged that the surface of the outdoor condenser 4 has basically met the conditions for frosting. When the outdoor ambient temperature is much higher than the surface temperature of the outdoor condenser 4, the outdoor ambient heat is transferred to the outdoor condenser 4, which will cause the surface of the outdoor condenser 4 to heat up rapidly and not meet the conditions for frosting; when the outdoor ambient temperature is much lower than the surface temperature of the outdoor condenser 4, the surface of the outdoor condenser 4 will cool down rapidly and meet the conditions for freezing, which is a strong obstacle to the reliable operation of the heat pump air-conditioning system. Therefore, as a preference, the second threshold value can be set to 5°C, that is, when the temperature difference detected by the first temperature sensor and the second temperature sensor is less than 5°C, the outdoor ambient temperature will neither be excessively higher than the surface temperature of the outdoor condenser 4 nor be excessively lower than the surface temperature of the outdoor condenser 4 to cause freezing, thereby satisfying the conditions for frosting on the surface of the outdoor condenser 4.

[0041] On the basis that the surface temperature detected by the second temperature sensor is less than the first threshold value, and the temperature difference detected by the first temperature sensor and the second temperature sensor is less than the second threshold value, the headwind speed on the surface of the outdoor condenser 4 and the relative humidity of the outdoor environment become important factors for the degree of frost. It can be understood by those skilled in the art that the thicker the frost layer on the surface of the outdoor condenser 4, the greater the obstruction to the air flow, and the smaller the air flow on the surface of the outdoor condenser 4, and the smaller the headwind speed. The greater the relative humidity in the air, the more obvious the frost on the surface of the outdoor condenser 4. Therefore, according to the headwind speed on the surface of the outdoor condenser 4 and the relative humidity of the outdoor environment, the present invention divides the defrost mode into the first defrost mode and the second defrost mode.

[0042] When the headwind speed detected by the wind speed sensor is less than the third threshold and the outdoor environment relative humidity detected by the relative humidity sensor is greater than the fourth threshold, the heat pump air-conditioning system enters the first defrost mode; when the headwind speed detected by the wind speed sensor is less than the fifth threshold and the outdoor environment relative humidity detected by the relative humidity sensor is greater than the sixth threshold, the heat pump air-conditioning system enters the second defrost mode, the fifth threshold is less than the third threshold, and the sixth threshold is greater than the fourth threshold.

[0043] For example, the third threshold value can be set to 4m / s, the fifth threshold value can be set to 2m / s, the fourth threshold value can be set to 60%, and the sixth threshold value can be set to 85%. That is, when the headwind speed detected by the wind speed sensor is between 2m / s-4m / s and the relative humidity of the outdoor environment is between 65%-85%, in other words, when the headwind speed is relatively large and the relative humidity of the outdoor environment is relatively small, the degree of frost on the surface of the outdoor condenser 4 is relatively small, and the thickness of the frost layer is small. At this time, the heat pump air-conditioning system can be made to enter the first defrost mode, and the defrost solenoid valve 8 is energized to connect the seventh valve port and the outdoor evaporator 9, and the fourth valve port of the four-way valve 2 is connected to the outdoor evaporator 9. Part of the outflowing refrigerant gas enters the indoor evaporator 3 to complete the heating cycle, and the other part of the refrigerant gas flows to the outdoor evaporator 9 through the seventh valve port of the three-way valve 7 and the defrost solenoid valve 8. The refrigerant gas condenses in the outdoor evaporator 9 and releases heat, and the heat is dispersed on the surface of the outdoor evaporator 9 and in the surrounding air. Since the outdoor evaporator 9 is adjacent to the outdoor condenser 4, the heat emitted by the outdoor evaporator 9 is transferred to the outdoor condenser 4, which is sufficient to melt the frost layer on the surface of the outdoor condenser 4. Therefore, in the first defrost mode, the air supply device 10 can be kept closed to save energy consumption and reduce the burden on the heat pump air-conditioning system. When the headwind speed detected by the wind speed sensor is less than 2m / s and the relative humidity of the outdoor environment is greater than 85%, in other words, when the headwind speed is relatively small and the relative humidity of the outdoor environment is relatively large, the frost on the surface of the outdoor condenser 4 is most serious. At this time, the heat pump air-conditioning system can enter the second defrost mode, and the controller controls the air supply device 10 to turn on and supply air to the outdoor evaporator 9. The cold air blown out by the air supply device 10 exchanges heat with the heat on the surface of the outdoor evaporator 9 and the heat in the air around the outdoor evaporator 9 to form hot air. The hot air blows toward the outdoor condenser 4 to quickly heat and melt the frost layer on the surface of the outdoor condenser 4, thereby ensuring the reliable operation of the heat pump air-conditioning system.

[0044] Further preferably, when the surface temperature detected by the second temperature sensor is less than a first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a third threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a fourth threshold for a first preset time period, the heat pump air-conditioning system enters the first defrost mode; when the surface temperature detected by the second temperature sensor is less than the first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a fifth threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a sixth threshold for a second preset time period, the heat pump air-conditioning system enters the second defrost mode.

[0045] What those skilled in the art can understand is that, when the outdoor temperature, the surface temperature of the outdoor condenser 4, the headwind speed, and the relative humidity of the outdoor environment have just reached the critical conditions for the heat pump air-conditioning system to enter the first defrost mode, the surface of the outdoor condenser 4 has just begun to frost, and the frost layer is not very obvious, which has little effect on the heating performance of the heat pump air-conditioning system. Therefore, the first defrost mode can be temporarily not turned on, and the first defrost mode can be turned on after the first preset time period. For example, the first preset time period can be set to 1 hour. When the frost layer on the surface of the outdoor condenser 4 accumulates to a certain thickness, the first defrost mode is turned on. Compared with entering the first defrost mode too early, energy consumption is further saved and the operation time of the high-efficiency heating mode is extended. Similarly, when the outdoor temperature, the surface temperature of the outdoor condenser 4, the headwind speed, and the relative humidity of the outdoor environment have just reached the critical conditions for the heat pump air-conditioning system to enter the second defrost mode, the heat pump air-conditioning system can continue to operate in the first defrost mode for a period of time and then start the second defrost mode after a second preset time period. For example, the second preset time period can be set to 30 minutes. The second defrost mode is turned on when the frost layer on the surface of the outdoor condenser 4 accumulates thicker. Compared with entering the second defrost mode too early, the opening time of the air supply device 10 is shortened, thereby further saving energy consumption.

[0046] Further, the present application provides two methods for terminating the defrost mode of the heat pump air conditioning system, including the following examples:

[0047] Example 1: In either the first defrost mode or the second defrost mode, when the surface temperature of the outdoor condenser 4 detected by the second temperature sensor is higher than the seventh threshold for a third preset time period, the defrost solenoid valve 8 is powered off.

[0048] In this example, when the heat pump air conditioning system is in the first defrost mode, as the outdoor evaporator 9 transfers heat to the outdoor condenser 4, or when the heat pump air conditioning system is in the second defrost mode, the air supply device 10 blows hot air to the outdoor condenser 4 via the outdoor evaporator 9, the temperature of the outdoor condenser 4 continues to rise, and when the surface temperature of the outdoor condenser 4 detected by the second temperature sensor is higher than the seventh threshold for a third preset time, the condition of melting all the frost layers is met, and the defrost solenoid valve 8 can be closed. For example, the seventh threshold can be 10°C, and the third preset time can be 2 hours.

[0049] Example 2: The heat pump air-conditioning system also includes a third temperature sensor electrically connected to the controller, and the third temperature sensor is used to detect the indoor ambient temperature; when the temperature difference measured by the second temperature sensor and the third temperature sensor is less than the eighth threshold value for a fourth preset time period, the defrost solenoid valve 8 is powered off.

[0050] In this example, the temperature difference between the indoor ambient temperature and the surface temperature of the outdoor condenser 4 and the duration are used to determine whether to cut off the power to the defrost solenoid valve 8 to terminate the defrost mode. The smaller the temperature difference between the indoor ambient temperature and the surface temperature of the outdoor condenser 4, the higher the surface temperature of the outdoor condenser 4, and the smaller the probability of frost on the surface. For example, the fifth threshold value can be set to 10°C. In the heating mode, the temperature in the cab is generally 15°C-25°C. At this time, the surface temperature of the outdoor condenser 4 should be 5°C-15°C, and the defrost effect is better. For example, the fourth preset duration can be set to 2 hours.

[0051] As a preferred embodiment, in the first defrost mode, the operating frequency of the compressor 1 is a first preset frequency; in the second defrost mode, the operating frequency of the compressor 1 is a second preset frequency, and the second preset frequency is greater than the first preset frequency.

[0052] What those skilled in the art can understand is that the second preset frequency is greater than the first preset frequency, that is, in the first defrost mode, the operating frequency of the compressor 1 is relatively low, and in the second defrost mode, the operating frequency of the compressor 1 is relatively high. Therefore, the defrost speed and defrost effect can be improved by increasing the frequency of the compressor 1.

[0053] As a preferred embodiment of the present invention, the opening of the first expansion valve 5 or the opening of the second expansion valve 11 can be adjusted. Of course, the opening of the first expansion valve 5 and the opening of the second expansion valve 11 can also be adjusted.

[0054] It is understood by those skilled in the art that the defrost speed can be changed by adjusting the opening of the first expansion valve 5 and the opening of the second expansion valve 11, and changing the flow of the refrigerant in the first expansion valve 5 and the second expansion valve 11. For example, after the defrost mode is turned on, the opening of the first expansion valve 5 can be reduced and the opening of the second expansion valve 11 can be increased, thereby increasing the rate at which the refrigerant gas enters the defrost solenoid valve 8, accelerating the circulation of the refrigerant gas between the defrost solenoid valve 8 and the second expansion valve 11, which helps to increase the heat of the outdoor evaporator 9, thereby helping to speed up the defrost speed and improve the defrost effect.

[0055] As a preferred embodiment of the present invention, the air supply device 10 can also supply air in different directions.

[0056] Those skilled in the art will appreciate that by enabling the air supply device 10 to supply air in different directions, it is convenient to blow air to the entire surface of the outdoor condenser 4, thereby ensuring that all parts of the outdoor condenser 4 can obtain a good defrosting effect. The air blowing device may be a blower or a fan.

[0057] A pure electric light truck provided by the present invention includes a heat pump air conditioning system, wherein the heat pump air conditioning system is the heat pump air conditioning system capable of defrosting as described above.

[0058] It should be noted that since the pure electric light truck provided by the present invention includes the heat pump air-conditioning system capable of defrosting in any one of the above-mentioned implementation modes, examples, and examples, the beneficial effects of the heat pump air-conditioning system capable of defrosting are all included in the pure electric light truck provided by the present invention and will not be elaborated here.

[0059] Anything not described in the present invention can be achieved by adopting or drawing on existing technologies.

[0060] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0061] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A heat pump air conditioning system capable of defrosting, the heat pump air conditioning system having a cooling mode, a heating mode and a defrosting mode, characterized in that: The heat pump air conditioning system comprises a compressor, a four-way valve, an indoor evaporator, an outdoor condenser, a first expansion valve and a liquid storage device; The compressor has an exhaust port and an air return port; The four-way valve has a first valve port, a second valve port, a third valve port and a fourth valve port, the first valve port is connected to the exhaust port, the second valve port is connected to the return port, and one of the third valve port and the fourth valve port is connected to the first valve port, and when one of the third valve port and the fourth valve port is connected to the first valve port, the other is connected to the second valve port; One end of the indoor evaporator is connected to the fourth valve port, and the other end is connected to the liquid storage device through the first expansion valve; One end of the outdoor condenser is connected to the third valve port, and the other end is connected to the liquid storage device; The heat pump air conditioning system also includes a three-way valve, a defrost solenoid valve, an outdoor evaporator, an air supply device, a second expansion valve and a controller; The three-way valve has a fifth valve port, a sixth valve port and a seventh valve port, the fifth valve port and the sixth valve port are connected to the fluid path between the fourth valve port and the indoor evaporator, the seventh valve port is connected to one end of the outdoor evaporator through the defrost solenoid valve, and the other end of the outdoor evaporator is connected to the fluid path between the first expansion valve and the liquid storage device through the second expansion valve; The outdoor evaporator is arranged at a position adjacent to the outdoor condenser, the air supply device is electrically connected to the controller, and the air supply device can supply air toward the outdoor condenser via the outdoor evaporator; The heat pump air conditioning system further includes a first temperature sensor, a second temperature sensor, a wind speed sensor and a relative humidity sensor, wherein the first temperature sensor is used to detect the outdoor ambient temperature, the second temperature sensor is used to detect the surface temperature of the outdoor condenser, the wind speed sensor is used to detect the oncoming wind speed on the surface of the outdoor condenser, and the relative humidity sensor is used to detect the outdoor ambient relative humidity, and the first temperature sensor, the second temperature sensor, the wind speed sensor and the relative humidity sensor are all electrically connected to the controller to control the power on and off of the defrost solenoid valve through the controller; When the heat pump air-conditioning system is in heating mode, the first temperature sensor, the second temperature sensor, the wind speed sensor and the relative humidity sensor respectively transmit outdoor ambient temperature information, surface temperature information of the outdoor condenser, headwind speed information of the outdoor condenser surface and outdoor ambient relative humidity information to the controller, and the controller can energize the defrost solenoid valve according to the outdoor ambient temperature information, surface temperature information, headwind speed information and outdoor ambient relative humidity information to enable the heating mode and defrost mode of the heat pump air-conditioning system to run in parallel.

2. A heat pump air conditioning system capable of defrosting according to claim 1, characterized in that: When the surface temperature detected by the second temperature sensor is less than a first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a third threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a fourth threshold, the heat pump air conditioning system enters a first defrost mode, the defrost solenoid valve is energized to connect the seventh valve port with the outdoor evaporator, and the air supply device remains closed; When the surface temperature detected by the second temperature sensor is lower than the first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is lower than the second threshold, the headwind speed detected by the wind speed sensor is lower than the fifth threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is higher than the sixth threshold, the heat pump air-conditioning system enters the second defrost mode, the defrost solenoid valve is energized to connect the seventh valve port and the outdoor evaporator, the controller controls the air supply device to open and supply air to the outdoor evaporator, the airflow is heat-exchanged through the outdoor evaporator into hot air and then flows to the outdoor condenser, the fifth threshold is lower than the third threshold, and the sixth threshold is higher than the fourth threshold.

3. A heat pump air conditioning system capable of defrosting according to claim 2, characterized in that: When the surface temperature detected by the second temperature sensor is less than a first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is less than a second threshold, the headwind speed detected by the wind speed sensor is less than a third threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is greater than a fourth threshold for a first preset time period, the heat pump air conditioning system enters the first defrost mode; When the surface temperature detected by the second temperature sensor is lower than the first threshold, the temperature difference detected by the first temperature sensor and the second temperature sensor is lower than the second threshold, the headwind speed detected by the wind speed sensor is lower than the fifth threshold, and the outdoor environment relative humidity detected by the relative humidity sensor is higher than the sixth threshold for a second preset time period, the heat pump air-conditioning system enters the second defrost mode.

4. A heat pump air conditioning system capable of defrosting according to claim 3, characterized in that: In either the first defrost mode or the second defrost mode, when the surface temperature of the outdoor condenser detected by the second temperature sensor is higher than the seventh threshold for a third preset time period, the defrost solenoid valve is powered off.

5. The heat pump air conditioning system capable of defrosting according to claim 3, characterized in that: The heat pump air conditioning system further comprises a third temperature sensor electrically connected to the controller, wherein the third temperature sensor is used to detect the indoor ambient temperature; When the time duration during which the temperature difference measured by the second temperature sensor and the third temperature sensor is less than the eighth threshold is a fourth preset time duration, the defrost solenoid valve is powered off.

6. A heat pump air conditioning system capable of defrosting according to claim 2, characterized in that: In the first defrost mode, the operating frequency of the compressor is a first preset frequency; In the second defrost mode, the operating frequency of the compressor is a second preset frequency, and the second preset frequency is greater than the first preset frequency.

7. The heat pump air conditioning system capable of defrosting according to claim 1, characterized in that: The opening degree of the first expansion valve and / or the opening degree of the second expansion valve is adjustable.

8. The heat pump air conditioning system capable of defrosting according to claim 1, characterized in that: The air supply device can supply air in different directions.

9. A pure electric light truck, including a heat pump air conditioning system, characterized in that: The heat pump air conditioning system is a heat pump air conditioning system capable of defrosting as claimed in any one of claims 1 to 8.

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