Heat pump system of air conditioner, air conditioner and control method of air conditioner

Abstract

The invention relates to the field of air conditioners, in particular to a heat pump system of an air conditioner, the air conditioner and a control method of the air conditioner, and aims to solve the problem that an existing air conditioner cannot achieve dehumidification under the working conditions of refrigeration, normal heating and ultralow-temperature heating. In order to achieve the purpose, the heat pump system comprises a first refrigerant loop, a second refrigerant loop, a first heat exchanger, a first throttling device and a second heat exchanger, a second compressor, a third heat exchanger, a second throttling device and a fourth heat exchanger are sequentially arranged on the second refrigerant loop; the second compressor and / or the first compressor, the first heat exchanger, the second heat exchanger, the third throttling device, the third heat exchanger and the fourth heat exchanger are sequentially arranged on a third refrigerant loop; the reversing valve assembly is used for switching the flow directions of refrigerants in the first refrigerant loop, the second refrigerant loop and the third refrigerant loop; the on-off states of the first refrigerant loop, the second refrigerant loop and the third refrigerant loop can be controlled respectively.

Description

Technical Field

[0001] The present invention relates to the field of air conditioners, and in particular provides a heat pump system of an air conditioner, an air conditioner and a control method of the air conditioner. Background Art

[0002] The current air conditioner can maintain good heating performance when the outer ring temperature is above -20℃, with a COP of about 2-5. When the outer ring temperature is below -20℃, the heating capacity and COP will be greatly reduced. The current solution is generally to increase enthalpy by adding air, but its heating COP is still less than 2. For users, the lower the temperature, the greater the heating demand.

[0003] In order to achieve a good heating effect in ultra-low temperature conditions, current air conditioners use a cascade heat pump system. As user demand increases, users want to be able to dehumidify in cooling, normal heating, and ultra-low temperature heating conditions. However, the current air conditioner heat pump system cannot meet this requirement.

[0004] Accordingly, the art requires a new heat pump system for an air conditioner, an air conditioner and a control method for the air conditioner to solve the above problems. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem that the existing air conditioner cannot satisfy the dehumidification under refrigeration, normal heating and ultra-low temperature heating conditions.

[0006] In a first aspect, the present invention provides a heat pump system for an air conditioner, characterized in that the heat pump system comprises: a first refrigerant circuit, on which a first compressor, a first heat exchanger, a first throttling device and a second heat exchanger are sequentially arranged; a second refrigerant circuit, on which a second compressor, a third heat exchanger, a second throttling device and a fourth heat exchanger are sequentially arranged; a third refrigerant circuit and a third throttling device, wherein the second compressor and / or the first compressor, the first heat exchanger, the second heat exchanger, the third throttling device, the third heat exchanger and the fourth heat exchanger are sequentially arranged on the third refrigerant circuit; a reversing valve assembly, wherein the reversing valve assembly is used to switch the refrigerant flow direction in the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit; wherein the first heat exchanger is arranged in the first air duct, and the second heat exchanger and the third heat exchanger are arranged in the second air duct; the on-off of the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit can be controlled separately.

[0007] In the preferred technical solution of the heat pump system of the above-mentioned air conditioner, the heat pump system also includes a first refrigerant branch and a second refrigerant branch, the two ends of the first refrigerant branch are respectively connected to the first refrigerant circuit between the first compressor and the second heat exchanger and the second refrigerant circuit between the second compressor and the third heat exchanger, the two ends of the second refrigerant branch are respectively connected to the first refrigerant circuit between the first refrigerant branch and the second heat exchanger and the second refrigerant circuit between the first refrigerant branch and the third heat exchanger; the first refrigerant circuit connecting the first refrigerant branch, the first compressor, the first heat exchanger, the second heat exchanger and the second refrigerant branch, the second refrigerant branch, the second refrigerant circuit connecting the second refrigerant branch, the third heat exchanger, the fourth heat exchanger, the second compressor, the second refrigerant circuit of the first refrigerant branch and the first refrigerant branch constitute the third refrigerant circuit.

[0008] In the preferred technical solution of the heat pump system of the above-mentioned air conditioner, a first solenoid valve is provided on the first refrigerant branch, a second solenoid valve and the third throttling device are provided on the second refrigerant branch, a third solenoid valve is provided on the first refrigerant circuit between the first refrigerant branch and the second refrigerant branch, and a fourth solenoid valve is provided on the second refrigerant circuit between the first refrigerant branch and the second refrigerant branch.

[0009] In the preferred technical scheme of the heat pump system of the above-mentioned air conditioner, the reversing valve assembly includes a first four-way reversing valve and a second four-way reversing valve, the first four-way reversing valve includes a first d port, a first s port, a first c port and a first e port, the first d port is connected to the output end of the first compressor, the first s port is connected to the input end of the first compressor, the first c port is connected to the first refrigerant circuit between the first heat exchanger and the first compressor, the first e port is connected to the end of the first refrigerant branch away from the second compressor, the second four-way reversing valve includes a second d port, a second s port, a second c port and a second e port, the second d port is connected to the output end of the second compressor, the second s port is connected to the input end of the second compressor, the second c port is connected to the second refrigerant circuit between the second refrigerant branch and the first refrigerant branch, the second e port is connected to the second refrigerant circuit between the fourth heat exchanger and the second compressor, and the fourth solenoid valve is arranged between the first refrigerant branch and the second d port.

[0010] In the preferred technical solution of the heat pump system of the above-mentioned air conditioner, the first throttling device, the second throttling device and the third throttling device are all electronic expansion valves.

[0011] In another aspect, the present invention further provides an air conditioner, comprising the heat pump system of the air conditioner described in any one of the above embodiments.

[0012] On the other hand, the present invention also provides a control method for an air conditioner, the air conditioner includes a heat pump system, the heat pump system includes: a first refrigerant circuit, a high-temperature refrigerant is provided in the first refrigerant circuit, and a first compressor, a first heat exchanger, a first throttling device and a second heat exchanger are sequentially provided on the first refrigerant circuit; a second refrigerant circuit, a low-temperature refrigerant is provided in the second refrigerant circuit, and a second compressor, a third heat exchanger, a second throttling device and a fourth heat exchanger are sequentially provided on the second refrigerant circuit; a third refrigerant circuit and a third throttling device, the second compressor and / or the first compressor The first heat exchanger, the second heat exchanger, the third throttling device, the third heat exchanger and the fourth heat exchanger are sequentially arranged on the third refrigerant circuit; a reversing valve assembly, the reversing valve assembly is used to switch the refrigerant flow direction in the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit; wherein the first heat exchanger is arranged in the first air duct, and the second heat exchanger and the third heat exchanger are arranged in the second air duct; the on-off of the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit can be controlled respectively; the control method comprises: in normal operation In the heating mode, the third refrigerant circuit is controlled to be connected, the first refrigerant circuit and the second refrigerant circuit are controlled to be blocked, and the first throttling device and the second throttling device are controlled to be fully opened; the second compressor and / or the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor and / or the first compressor to the first heat exchanger; in the ultra-low temperature heating mode, the third refrigerant circuit is controlled to be blocked, and the first refrigerant circuit and the second refrigerant circuit are controlled to be connected respectively; the second compressor and the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant in the first refrigerant circuit flows from the first compressor to the first heat exchanger, and the refrigerant in the second refrigerant circuit flows from the second compressor to the third heat exchanger; in the cooling mode, the third refrigerant circuit is controlled to be connected, the first refrigerant circuit is controlled to be blocked, and the first throttling device and the second throttling device are controlled to be fully opened; the second compressor and / or the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor and / or the first compressor to the fourth heat exchanger.

[0013] In the preferred technical solution of the control method of the above-mentioned air conditioner, the heat pump system also includes a first refrigerant branch and a second refrigerant branch, the two ends of the first refrigerant branch are respectively connected to the first refrigerant circuit between the first compressor and the second heat exchanger and the second refrigerant circuit between the second compressor and the third heat exchanger, and the two ends of the second refrigerant branch are respectively connected to the first refrigerant circuit between the first refrigerant branch and the second heat exchanger and the second refrigerant circuit between the first refrigerant branch and the third heat exchanger; the first refrigerant circuit connecting the first refrigerant branch, the first compressor, the first heat exchanger, the second heat exchanger and the second refrigerant branch, the second refrigerant circuit connecting the second refrigerant branch, the third heat exchanger, the fourth heat exchanger, the second compressor, the second refrigerant circuit of the first refrigerant branch and the first refrigerant branch constitute the third refrigerant circuit; the first refrigerant branch is provided with a first solenoid valve, the second refrigerant branch is provided with a second solenoid valve and the third throttling device, the first refrigerant circuit between the first refrigerant branch and the second refrigerant branch A third solenoid valve is provided on the first refrigerant branch, and a fourth solenoid valve is provided on the second refrigerant circuit between the first refrigerant branch and the second refrigerant branch; the step of "under normal heating mode, controlling the third refrigerant circuit to be connected and controlling the first refrigerant circuit and the second refrigerant circuit to be blocked" further includes: under normal heating mode, controlling the first solenoid valve and the second solenoid valve to be opened, and controlling the third solenoid valve and the fourth solenoid valve to be closed; the step of "under ultra-low temperature heating mode, controlling the third refrigerant circuit to be blocked, and controlling the first refrigerant circuit and the second refrigerant circuit to be connected respectively" further includes: under ultra-low temperature heating mode, controlling the first solenoid valve and the second solenoid valve to be closed, and controlling the third solenoid valve and the fourth solenoid valve to be opened; the step of "under cooling mode, controlling the third refrigerant circuit to be connected and controlling the first refrigerant circuit to be blocked" further includes: under cooling mode, controlling the first solenoid valve and the second solenoid valve to be opened, and controlling the third solenoid valve to be closed; the control method also includes: under normal heating mode or cooling mode, controlling the first throttling device and the second throttling device to be fully opened.

[0014] In the preferred technical solution of the control method of the air conditioner, the control method further comprises: in the cooling mode, controlling the fourth solenoid valve to open.

[0015] In the preferred technical scheme of the control method of the above-mentioned air conditioner, the reversing valve assembly includes a first four-way reversing valve and a second four-way reversing valve, the first four-way reversing valve includes a first d port, a first s port, a first c port and a first e port, the first d port is connected to the output end of the first compressor, the first s port is connected to the input end of the first compressor, the first c port is connected to the first refrigerant circuit between the first heat exchanger and the first compressor, the first e port is connected to the end of the first refrigerant branch away from the second compressor, the second four-way reversing valve includes a second d port, a second s port, a second c port and a second e port, the second d port is connected to the output end of the second compressor, the second s port is connected to the input end of the second compressor, the second c port is connected to the second refrigerant circuit between the second refrigerant branch and the first refrigerant branch, the second e port is connected to the second refrigerant circuit between the fourth heat exchanger and the second compressor, and the fourth solenoid valve is arranged in the between the first refrigerant branch and the second d port; the steps of "controlling the action of the reversing valve assembly so that the refrigerant flows from the second compressor and / or the first compressor to the first heat exchanger" and "controlling the action of the reversing valve assembly so that the refrigerant in the first refrigerant circuit flows from the first compressor to the first heat exchanger, and the refrigerant in the second refrigerant circuit flows from the second compressor to the third heat exchanger" further include: controlling the first c port to be connected with the first d port, and the first e port to be connected with the first s port; controlling the second c port to be connected with the second d port, and the second e port to be connected with the second s port; the step of "controlling the action of the reversing valve assembly so that the refrigerant flows from the second compressor and / or the first compressor to the fourth heat exchanger" further include: controlling the first e port to be connected with the first d port, and the first c port to be connected with the first s port; controlling the second e port to be connected with the second d port, and the second c port to be connected with the second s port.

[0016] Those skilled in the art can understand that the heat pump system of the air conditioner of the present invention includes a first refrigerant circuit, a second refrigerant circuit, a third refrigerant circuit, a third throttling device and a reversing valve assembly, wherein a high-temperature refrigerant is provided in the first refrigerant circuit, and a first compressor, a first heat exchanger, a first throttling device and a second heat exchanger are sequentially provided on the first refrigerant circuit; a low-temperature refrigerant is provided in the second refrigerant circuit, and a second compressor, a third heat exchanger, a second throttling device and a fourth heat exchanger are sequentially provided on the second refrigerant circuit; the second compressor and / or the first compressor, the first heat exchanger, the second heat exchanger, the third throttling device, the third heat exchanger and the fourth heat exchanger are sequentially provided on the third refrigerant circuit; the reversing valve assembly is used to switch the refrigerant flow direction in the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit; the first heat exchanger is provided in the first air duct, and the second heat exchanger and the third heat exchanger are provided in the second air duct; the on-off of the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit can be controlled separately.

[0017] The above arrangement makes it possible that in normal heating mode, by controlling the connection of the third refrigerant circuit, the first refrigerant circuit and the second refrigerant circuit are blocked, the first throttling device and the second throttling device are fully opened; the second compressor and / or the first compressor are started; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor and / or the first compressor to the first heat exchanger. Thus, the first heat exchanger and the second heat exchanger are used as condensers, and the third heat exchanger and the fourth heat exchanger are used as evaporators. Since the first heat exchanger is separately arranged in an air duct, and the second heat exchanger and the third heat exchanger are arranged in an air duct, the indoor air can enter the first air duct, and return to the room after being heated by the first heat exchanger, so as to achieve the effect of heating the indoor air; the indoor air enters the second air duct, and after being cooled and dehumidified by the third heat exchanger, the air is temperature-adjusted by the second heat exchanger and then blown into the room, so that the heat pump system can dehumidify under heating conditions.

[0018] In the ultra-low temperature heating mode, the third refrigerant circuit is controlled to be blocked, and the first refrigerant circuit and the second refrigerant circuit are controlled to be connected respectively; the second compressor and the first compressor are controlled to start; the reversing valve assembly is controlled to operate, so that the refrigerant in the first refrigerant circuit flows from the first compressor to the first heat exchanger, and the refrigerant in the second refrigerant circuit flows from the second compressor to the third heat exchanger. The first heat exchanger and the third heat exchanger are used as condensers, and the second heat exchanger and the fourth heat exchanger are used as evaporators. Thus, the indoor air can enter the first air duct and return to the room after being heated by the first heat exchanger, so as to achieve the effect of heating the indoor air; the air enters the second air duct, is cooled and dehumidified by the second heat exchanger, and then flows to the room after the air is temperature-adjusted by the third heat exchanger, so that the heat pump system can dehumidify under ultra-low temperature heating conditions. Among them, since the low-temperature refrigerant in the second refrigerant circuit can still absorb heat and evaporate in an ultra-low temperature environment, the normal heat exchange of the fourth heat exchanger on the outdoor side can be guaranteed. The third heat exchanger, as the condenser of the low-temperature refrigeration cycle, can exchange heat with the second heat exchanger acting as the evaporator in the high-temperature refrigeration cycle, thereby ensuring the high air outlet temperature of the first heat exchanger, which has a significant improvement on the heating air in ultra-low ambient temperature.

[0019] In the cooling mode, the third refrigerant circuit is controlled to be connected, the first refrigerant circuit is controlled to be blocked, and the first throttling device and the second throttling device are controlled to be fully opened; the second compressor and / or the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor and / or the first compressor to the fourth heat exchanger. The first heat exchanger and the second heat exchanger are used as evaporators, and the third heat exchanger and the fourth heat exchanger are used as condensers. Since the first heat exchanger is separately arranged in an air duct, and the second heat exchanger and the third heat exchanger are arranged in an air duct, the indoor air can enter the first air duct, and return to the room after being cooled by the first heat exchanger, so as to achieve the effect of cooling the indoor air; the air enters the second air duct, and after being cooled and dehumidified by the second heat exchanger, the air is adjusted in temperature by the third heat exchanger and then flows to the room, so that the heat pump system can dehumidify under the cooling condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0021] Figure 1 is a schematic diagram of the refrigerant flow direction of the heat pump system of the present invention in a normal heating mode;

[0022] Figure 2 is a schematic diagram of the refrigerant flow direction of the heat pump system of the present invention in the ultra-low temperature heating mode;

[0023] Figure 3 is a schematic diagram of the refrigerant flow direction of the heat pump system of the present invention in the cooling mode;

[0024] Figure 4 It is a main flow chart of the control method of the air conditioner of the present invention.

[0025] List of reference numerals:

[0026] 10-first compressor; 11-first four-way reversing valve; 12-first heat exchanger; 13-first throttling device; 14-second heat exchanger; 20-second compressor; 21-second four-way reversing valve; 22-third heat exchanger; 23-second throttling device; 24-fourth heat exchanger; 30-first solenoid valve; 31-second solenoid valve; 32-third solenoid valve; 33-fourth solenoid valve; 40-third throttling device; 50-first refrigerant circuit; 51-second refrigerant circuit; 52-first refrigerant branch; 53-second refrigerant branch. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios, which do not deviate from the principles of the present invention and are within the scope of protection of the present invention.

[0028] It should be noted that, in the description of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connected" 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 directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In addition, in the description of the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0029] like Figures 1 to 3As shown, in order to solve the problem that the existing air conditioner cannot satisfy the dehumidification under the conditions of refrigeration, normal heating and ultra-low temperature heating. The present invention provides a heat pump system for an air conditioner, the heat pump system includes a first refrigerant circuit 50 and a second refrigerant circuit 51, the refrigerant in the first refrigerant circuit 50 is a high-temperature refrigerant, such as the refrigerant medium R410A, the refrigerant in the second refrigerant circuit 51 is a low-temperature refrigerant, such as the refrigerant medium R134a, the first refrigerant circuit 50 is provided with a first compressor 10, a first heat exchanger 12, a first throttling device 13 and a second heat exchanger 14 in sequence, and the second refrigerant circuit 51 is provided with a second compressor 20, a third heat exchanger 22, a second throttling device 23 and a fourth heat exchanger 24 in sequence; the heat pump system also includes a first refrigerant branch 52 and a second refrigerant branch 53, the two ends of the first refrigerant branch 52 are respectively connected to the first compressor 10 and the second heat exchanger. 14 and the second refrigerant circuit 51 between the second compressor 20 and the third heat exchanger 22, the two ends of the second refrigerant branch 53 are respectively connected to the first refrigerant circuit 50 between the first refrigerant branch 52 and the second heat exchanger 14 and the second refrigerant circuit 51 between the first refrigerant branch 52 and the third heat exchanger 22, the first refrigerant circuit 50 connecting the first refrigerant branch 52, the first compressor 10, the first heat exchanger 12, the second heat exchanger 14 and the second refrigerant branch, the second refrigerant branch 53, the second refrigerant circuit 51 connecting the second refrigerant branch 53, the third heat exchanger 22, the fourth heat exchanger 24, the second compressor 20, the first refrigerant branch 52 and the first refrigerant branch 52 constitute a third refrigerant circuit. The first refrigerant branch 52 is provided with a first solenoid valve 30, the second refrigerant branch 53 is provided with a second solenoid valve 31 and a third throttling device 40, the first refrigerant circuit 50 between the first refrigerant branch 52 and the second refrigerant branch 53 is provided with a third solenoid valve 32, and the second refrigerant circuit 51 between the first refrigerant branch 52 and the second refrigerant branch 53 is provided with a fourth solenoid valve 33. The heat pump system of the present invention further includes a reversing valve assembly, which is used to switch the refrigerant flow direction in the first refrigerant circuit 50, the second refrigerant circuit 51, and the third refrigerant circuit. The first heat exchanger 12 is arranged in the first air duct, and the second heat exchanger 14 and the third heat exchanger 22 are arranged in the second air duct. Specifically, the first heat exchanger 12, the second heat exchanger 14 and the third heat exchanger 22 are arranged on the indoor side, and the fourth heat exchanger 24 is arranged on the outdoor side. The air in the first air duct and the second air duct can flow to the indoor side. The first air duct and the second air duct can both be provided with fans, and the fan in the second air duct can be a forward and reverse fan. Preferably, the first throttling device 13, the second throttling device 23 and the third throttling device 40 are all electronic expansion valves.

[0030] Reference Figure 1In normal heating mode, the first solenoid valve 30 and the second solenoid valve 31 are controlled to be open, and the third solenoid valve 32 and the fourth solenoid valve 33 are controlled to be closed, that is, the first refrigerant circuit 50 and the second refrigerant circuit 51 are blocked, so that the third refrigerant circuit is connected, and the first throttling device 13 and the second throttling device 23 are controlled to be fully opened or slightly throttled, and the second compressor 20 and / or the first compressor 10 are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor 20 and / or the first compressor 10 to the first heat exchanger 12.

[0031] In this case, only the first compressor 10 can work, or only the second compressor 20 can work, or the first compressor 10 and the second compressor 20 can work at the same time, and the refrigerant flows from the first compressor 10 and / or the second compressor 20 to the first heat exchanger 12 and the second heat exchanger 14, flows through the third heat exchanger 22 and the fourth heat exchanger 24 after being throttled by the third throttling device 40, and then returns to the first compressor 10 and / or the second compressor 20. That is, the first heat exchanger 12 and the second heat exchanger 14 are used as condensers, so as to heat the surrounding air, and the third heat exchanger 22 and the fourth heat exchanger 24 are used as evaporators, so as to cool the surrounding air. Since the first heat exchanger 12 is separately arranged in an air duct, and the second heat exchanger 14 and the third heat exchanger 22 are arranged in an air duct, the indoor air can enter the first air duct, and return to the room after being heated by the first heat exchanger 12, so as to achieve the effect of heating the indoor air; the fan in the second air duct rotates forward, and the indoor air quickly enters the second air duct under the action of the fan, and after being cooled and dehumidified by the third heat exchanger 22, the air is temperature-adjusted by the second heat exchanger 14 and then blown into the room, so that the heat pump system can dehumidify under heating conditions.

[0032] Reference Figure 2 In the ultra-low temperature heating mode, the first solenoid valve 30 and the second solenoid valve 31 are controlled to be closed, and the third solenoid valve 32 and the fourth solenoid valve 33 are controlled to be opened, that is, the third refrigerant circuit is blocked, the first refrigerant circuit 50 is connected and the second refrigerant circuit 51 is connected, and the second compressor 20 and the first compressor 10 are controlled to start, and the reversing valve assembly is controlled to operate, so that the refrigerant in the first refrigerant circuit 50 flows from the first compressor 10 to the first heat exchanger 12, and the refrigerant in the second refrigerant circuit 51 flows from the second compressor 20 to the third heat exchanger 22.

[0033] In this case, both the first compressor 10 and the second compressor 20 are working, and the refrigerant in the first refrigerant circuit 50 flows from the first compressor 10 to the first heat exchanger 12, flows to the second heat exchanger 14 after being throttled by the first throttling device 13, and then returns to the first compressor 10. The refrigerant in the second refrigerant circuit 51 flows from the second compressor 20 to the third heat exchanger 22, flows to the fourth heat exchanger 24 after being throttled by the second throttling device 23, and then returns to the second compressor 20. That is, the first heat exchanger 12 and the third heat exchanger 22 are used as condensers, and the second heat exchanger 14 and the fourth heat exchanger 24 are used as evaporators. Thus, the indoor air can enter the first air duct, be heated by the first heat exchanger 12, and then return to the room, so as to achieve the effect of heating the indoor air; the fan in the second air duct can rotate in the opposite direction, and the indoor air can quickly enter the second air duct under the action of the fan, and after being cooled and dehumidified by the second heat exchanger 14, the air is temperature-adjusted by the third heat exchanger 22 and then blown into the room, so that the heat pump system can dehumidify under ultra-low temperature heating conditions. Among them, since the low-temperature refrigerant in the second refrigerant circuit 51 can still absorb heat and evaporate in an ultra-low temperature environment, the normal heat exchange of the fourth heat exchanger 24 on the outdoor side can be ensured, and the third heat exchanger 22, as the condenser of the low-temperature refrigeration cycle, can exchange heat with the second heat exchanger 14 acting as the evaporator in the high-temperature refrigeration cycle, so as to ensure the high outlet air temperature of the first heat exchanger 12, which has a significant improvement effect on the ultra-low ambient temperature heating air.

[0034] Reference Figure 3 In the cooling mode, the first solenoid valve 30 and the second solenoid valve 31 are controlled to be opened, the third solenoid valve 32 is controlled to be closed, and the fourth solenoid valve 33 is controlled to be opened, so that the third refrigerant circuit is connected and the first refrigerant circuit 50 is blocked; the first throttling device 13 and the second throttling device 23 are controlled to be fully opened or slightly throttled, and the second compressor 20 and / or the first compressor 10 are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor 20 and / or the first compressor 10 to the fourth heat exchanger 24.

[0035] In this case, only the first compressor 10 can work, or only the second compressor 20 can work, or the first compressor 10 and the second compressor 20 can work at the same time, and the refrigerant flows from the first compressor 10 and / or the second compressor 20 to the fourth heat exchanger 24 and the third heat exchanger 22 in sequence, and then flows to the second heat exchanger 14 and the first heat exchanger 12 in sequence after being throttled by the third throttling device 40, and then returns to the first compressor 10 and the second compressor 20. That is, the first heat exchanger 12 and the second heat exchanger 14 are used as evaporators, and the third heat exchanger 22 and the fourth heat exchanger 24 are used as condensers. Since the first heat exchanger 12 is separately arranged in an air duct, and the second heat exchanger 14 and the third heat exchanger 22 are arranged in an air duct, the indoor air can enter the first air duct, and return to the room after being cooled by the first heat exchanger 12, so as to achieve the effect of cooling the indoor air; the fan in the second air duct rotates in the opposite direction, and the indoor air quickly enters the second air duct under the action of the fan, and after being cooled and dehumidified by the second heat exchanger 14, the air is temperature-adjusted by the third heat exchanger 22 and then blown into the room, so that the heat pump system can dehumidify under cooling conditions.

[0036] As a possible implementation, the reversing valve assembly includes a first four-way reversing valve 11 and a second four-way reversing valve 21, the first four-way reversing valve 11 includes a first d port, a first s port, a first c port and a first e port, the first d port is connected to the output end of the first compressor 10, the first s port is connected to the input end of the first compressor 10, the first c port is connected to the first refrigerant circuit 50 between the first heat exchanger 12 and the first compressor 10, and the first e port is connected to the end of the first refrigerant branch 52 away from the second compressor 20 The second four-way reversing valve 21 includes a second d port, a second s port, a second c port and a second e port. The second d port is connected to the output end of the second compressor 20, the second s port is connected to the input end of the second compressor 20, the second c port is connected to the second refrigerant circuit 51 between the second refrigerant branch 53 and the first refrigerant branch 52, the second e port is connected to the second refrigerant circuit 51 between the fourth heat exchanger 24 and the second compressor 20, and the fourth solenoid valve 33 is arranged on the pipeline between the first refrigerant branch 52 and the second d port.

[0037] On the other hand, the present invention also provides an air conditioner, which includes the heat pump system described in any of the above embodiments. After the air conditioner has the above heat pump system, it can perform dehumidification in cooling mode, normal heating mode, and ultra-low temperature heating mode.

[0038] As a possible implementation, the air conditioner includes an indoor unit and an outdoor unit, the indoor unit is provided with the above-mentioned first air duct and second air duct, the first air duct is provided with a first heat exchanger 12, the second air duct is provided with a second heat exchanger 14 and a third heat exchanger 22, the outdoor unit is provided with a third air duct, and the third air duct is provided with a fourth heat exchanger 24. The indoor unit is provided with a first air outlet, a second air outlet, a third air outlet and a fourth air outlet, the first air outlet and the second air outlet are respectively connected to the two ends of the first air duct, the third air outlet and the fourth air outlet are respectively connected to the two ends of the second air duct, the second air duct is provided with a forward and reverse fan, the first air duct is provided with a first fan, and the third air duct is provided with a second fan.

[0039] like Figure 4 As shown, the control method of the air conditioner of the present invention is introduced below, and the control method includes the following steps.

[0040] Step S100: In normal heating mode, control the third refrigerant circuit to be connected, control the first refrigerant circuit and the second refrigerant circuit to be blocked; control the second compressor and / or the first compressor to start; control the reversing valve assembly to operate, so that the refrigerant flows from the second compressor and / or the first compressor to the first heat exchanger.

[0041] Furthermore, in the normal heating mode, the first solenoid valve and the second solenoid valve are controlled to be opened, the third solenoid valve and the fourth solenoid valve are controlled to be closed, the first throttling device and the second throttling device are controlled to be fully opened, at which time the third throttling device is throttling, the second compressor and / or the first compressor are controlled to start, the first c port is controlled to be connected to the first d port, and the first e port is controlled to be connected to the first s port; the second c port is controlled to be connected to the second d port, and the second e port is controlled to be connected to the second s port.

[0042] That is, in normal heating mode, the refrigerant flow direction is: first compressor-first d port-first c port-first heat exchanger-second heat exchanger-third throttling device-third heat exchanger-fourth heat exchanger-second e port-second s port-second compressor-first e port-first s port-first compressor.

[0043] In this case, the first heat exchanger and the second heat exchanger are used as condensers, and the third heat exchanger and the fourth heat exchanger are used as evaporators. Since the first heat exchanger is set in a single air duct, and the second heat exchanger and the third heat exchanger are set in a single air duct, the indoor air can enter the first air duct, and return to the room after being heated by the first heat exchanger, so as to achieve the effect of heating the indoor air; the fan in the second air duct rotates forward, and the indoor air quickly enters the second air duct under the action of the fan, and after being cooled and dehumidified by the third heat exchanger, the air is temperature-adjusted by the second heat exchanger and then blown into the room, so that the heat pump system can dehumidify under heating conditions.

[0044] Step S200: In the ultra-low temperature heating mode, the third refrigerant circuit is controlled to be blocked, and the first refrigerant circuit and the second refrigerant circuit are controlled to be connected respectively; the second compressor and the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant in the first refrigerant circuit flows from the first compressor to the first heat exchanger, and the refrigerant in the second refrigerant circuit flows from the second compressor to the third heat exchanger.

[0045] Furthermore, in the ultra-low temperature heating mode, the first c port is controlled to be connected with the first d port, and the first e port is controlled to be connected with the first s port; the second c port is controlled to be connected with the second d port, and the second e port is controlled to be connected with the second s port; the first solenoid valve and the second solenoid valve are controlled to be closed, and the third solenoid valve and the fourth solenoid valve are controlled to be opened; the second compressor and the first compressor are controlled to start. At this time, the first throttling device and the second throttling device are both in the throttling state.

[0046] That is, in the ultra-low temperature heating mode, the refrigerant flow direction in the first refrigerant circuit is: first compressor-first d port-first c port-first heat exchanger-first throttling device-second heat exchanger-first e port-first s port-first compressor. The refrigerant flow direction in the second refrigerant circuit is: second compressor-second d port-second c port-third heat exchanger-second throttling device-fourth heat exchanger-second e port-second s port-second compressor.

[0047] That is, the first heat exchanger and the third heat exchanger are used as condensers, and the second heat exchanger and the fourth heat exchanger are used as evaporators. Therefore, the indoor air can enter the first air duct, be heated by the first heat exchanger, and then return to the room, so as to achieve the effect of heating the indoor air; the fan in the second air duct can rotate in the opposite direction, and the indoor air quickly enters the second air duct under the action of the fan, and after being cooled and dehumidified by the second heat exchanger, the air is temperature-adjusted by the third heat exchanger and then blown into the room, so that the heat pump system can dehumidify under ultra-low temperature heating conditions. Among them, since the low-temperature refrigerant in the second refrigerant circuit can still absorb heat and evaporate in an ultra-low temperature environment, the normal heat exchange of the fourth heat exchanger on the outdoor side can be guaranteed. The third heat exchanger, as the condenser of the low-temperature refrigeration cycle, can exchange heat with the second heat exchanger acting as an evaporator in the high-temperature refrigeration cycle, so as to ensure the high outlet air temperature of the first heat exchanger, which has a significant improvement effect on the ultra-low ambient temperature heating air.

[0048] Step S300: In the cooling mode, the third refrigerant circuit is controlled to be connected, and the first refrigerant circuit is controlled to be blocked. At this time, the second refrigerant circuit can be controlled to be connected, and the first throttling device and the second throttling device can be controlled to be fully opened; the second compressor and / or the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor and / or the first compressor to the fourth heat exchanger.

[0049] Further, in the refrigeration mode, the first solenoid valve and the second solenoid valve are controlled to open, the third solenoid valve is controlled to close, the fourth solenoid valve is controlled to open, the first throttling device and the second throttling device are controlled to be fully opened, at this time the third throttling device is in a throttling state, the first e port is controlled to be connected with the first d port, and the first c port is controlled to be connected with the first s port; the second e port is controlled to be connected with the second d port, and the second c port is controlled to be connected with the second s port, and the second compressor and / or the first compressor are controlled to start.

[0050] That is, in the cooling mode, if both the first compressor and the second compressor are started, the refrigerant flow direction is: first compressor-first d port-first e port-second d port-second e port-fourth heat exchanger-third heat exchanger-third throttling device-second heat exchanger-first heat exchanger-first c port-first s port-first compressor. In addition, after the refrigerant reaches the third heat exchanger, it returns to the second compressor from the second c port-second s port, and the refrigerant flowing out of the second compressor converges to the second d port. Preferably, only the first compressor works, and the second compressor does not work.

[0051] That is, the first heat exchanger and the second heat exchanger are used as evaporators, and the third heat exchanger and the fourth heat exchanger are used as condensers. Since the first heat exchanger is set in a single air duct, and the second heat exchanger and the third heat exchanger are set in a single air duct, the indoor air can enter the first air duct, and return to the room after being cooled by the first heat exchanger, so as to achieve the effect of cooling the indoor air; the fan in the second air duct rotates in the opposite direction, and the indoor air quickly enters the second air duct under the action of the fan, and after being cooled and dehumidified by the second heat exchanger, the air is temperature-adjusted by the third heat exchanger and then blown into the room, so that the heat pump system can dehumidify under cooling conditions.

[0052] It is understandable that the normal heating mode, the ultra-low temperature heating mode and the cooling mode can be control buttons of the control terminal, such as a remote control or a mobile phone APP, etc., which are provided with three-mode selection buttons. Of course, one of the above modes can also be automatically executed after the program meets certain conditions.

[0053] Those skilled in the art can understand that the above-mentioned air conditioner also includes some other well-known structures, such as a processor, a controller, a memory, etc., wherein the memory includes but is not limited to a random access memory, a flash memory, a read-only memory, a programmable read-only memory, a volatile memory, a non-volatile memory, a serial memory, a parallel memory or a register, etc., and the processor includes but is not limited to a CPLD / FPGA, a DSP, an ARM processor, a MIPS processor, etc. In order to unnecessarily obscure the embodiments of the present disclosure, these well-known structures are not shown in the drawings.

[0054] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art can understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order, and they can be executed simultaneously (in parallel) or in a reverse order. For example, step S100, step S200, and step S300 can be executed in parallel or in a reverse order. These simple changes are within the scope of protection of the present invention.

[0055] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A heat pump system for an air conditioner, characterized in that: The heat pump system includes: A first refrigerant circuit, wherein a first compressor, a first heat exchanger, a first throttling device and a second heat exchanger are sequentially provided on the first refrigerant circuit; a second refrigerant circuit, wherein a second compressor, a third heat exchanger, a second throttling device and a fourth heat exchanger are sequentially arranged on the second refrigerant circuit; A third refrigerant circuit and a third throttling device, wherein the second compressor and / or the first compressor, the first heat exchanger, the second heat exchanger, the third throttling device, the third heat exchanger and the fourth heat exchanger are sequentially arranged on the third refrigerant circuit; A reversing valve assembly, the reversing valve assembly is used to switch the refrigerant flow direction in the first refrigerant circuit, the second refrigerant circuit, and the third refrigerant circuit; The first heat exchanger is arranged in the first air duct, and the second heat exchanger and the third heat exchanger are arranged in the second air duct; the on-off of the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit can be controlled separately.

2. The heat pump system of the air conditioner according to claim 1, characterized in that: The heat pump system further includes a first refrigerant branch and a second refrigerant branch, wherein two ends of the first refrigerant branch are respectively connected to a first refrigerant circuit between the first compressor and the second heat exchanger and a second refrigerant circuit between the second compressor and the third heat exchanger, and two ends of the second refrigerant branch are respectively connected to the first refrigerant circuit between the first refrigerant branch and the second heat exchanger and a second refrigerant circuit between the first refrigerant branch and the third heat exchanger; The third refrigerant circuit is formed by connecting the first refrigerant branch, the first compressor, the first heat exchanger, the second heat exchanger and the second refrigerant branch, the second refrigerant circuit connecting the second refrigerant branch, the third heat exchanger, the fourth heat exchanger, the second compressor, the second refrigerant circuit of the first refrigerant branch, and the first refrigerant branch.

3. The heat pump system of the air conditioner according to claim 2, characterized in that: A first solenoid valve is provided on the first refrigerant branch, a second solenoid valve and the third throttling device are provided on the second refrigerant branch, a third solenoid valve is provided on the first refrigerant circuit between the first refrigerant branch and the second refrigerant branch, and a fourth solenoid valve is provided on the second refrigerant circuit between the first refrigerant branch and the second refrigerant branch.

4. The heat pump system of the air conditioner according to claim 3, characterized in that: The reversing valve assembly includes a first four-way reversing valve and a second four-way reversing valve, the first four-way reversing valve includes a first d port, a first s port, a first c port and a first e port, the first d port is connected to the output end of the first compressor, the first s port is connected to the input end of the first compressor, the first c port is connected to the first refrigerant circuit between the first heat exchanger and the first compressor, the first e port is connected to the end of the first refrigerant branch away from the second compressor, the second four-way reversing valve includes a second d port, a second s port, a second c port and a second e port, the second d port is connected to the output end of the second compressor, the second s port is connected to the input end of the second compressor, the second c port is connected to the second refrigerant circuit between the second refrigerant branch and the first refrigerant branch, the second e port is connected to the second refrigerant circuit between the fourth heat exchanger and the second compressor, and the fourth solenoid valve is arranged between the first refrigerant branch and the second d port.

5. The heat pump system of the air conditioner according to claim 1, characterized in that: The first throttling device, the second throttling device and the third throttling device are all electronic expansion valves.

6. An air conditioner, characterized in that: The air conditioner comprises the heat pump system of the air conditioner according to any one of claims 1 to 5.

7. A method for controlling an air conditioner, the air conditioner comprising a heat pump system, the heat pump system comprising: A first refrigerant circuit, wherein a high-temperature refrigerant is provided in the first refrigerant circuit, and a first compressor, a first heat exchanger, a first throttling device, and a second heat exchanger are sequentially provided on the first refrigerant circuit; a second refrigerant circuit, wherein a low-temperature refrigerant is provided in the second refrigerant circuit, and a second compressor, a third heat exchanger, a second throttling device and a fourth heat exchanger are sequentially provided on the second refrigerant circuit; A third refrigerant circuit and a third throttling device, wherein the second compressor and / or the first compressor, the first heat exchanger, the second heat exchanger, the third throttling device, the third heat exchanger and the fourth heat exchanger are sequentially arranged on the third refrigerant circuit; A reversing valve assembly, the reversing valve assembly is used to switch the refrigerant flow direction in the first refrigerant circuit, the second refrigerant circuit, and the third refrigerant circuit; Wherein, the first heat exchanger is arranged in the first air duct, and the second heat exchanger and the third heat exchanger are arranged in the second air duct; the on-off of the first refrigerant circuit, the second refrigerant circuit and the third refrigerant circuit can be controlled respectively; The control method comprises: In normal heating mode, the third refrigerant circuit is controlled to be connected, the first refrigerant circuit and the second refrigerant circuit are controlled to be blocked, and the first throttling device and the second throttling device are controlled to be fully opened; the second compressor and / or the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor and / or the first compressor to the first heat exchanger; In the ultra-low temperature heating mode, the third refrigerant circuit is controlled to be blocked, and the first refrigerant circuit and the second refrigerant circuit are controlled to be connected respectively; the second compressor and the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant in the first refrigerant circuit flows from the first compressor to the first heat exchanger, and the refrigerant in the second refrigerant circuit flows from the second compressor to the third heat exchanger; In the cooling mode, the third refrigerant circuit is controlled to be connected, the first refrigerant circuit is controlled to be blocked, the first throttling device and the second throttling device are controlled to be fully opened; the second compressor and / or the first compressor are controlled to start; the reversing valve assembly is controlled to operate so that the refrigerant flows from the second compressor and / or the first compressor to the fourth heat exchanger.

8. The control method of the air conditioner according to claim 7, characterized in that: The heat pump system further includes a first refrigerant branch and a second refrigerant branch, wherein two ends of the first refrigerant branch are respectively connected to a first refrigerant circuit between the first compressor and the second heat exchanger and a second refrigerant circuit between the second compressor and the third heat exchanger, and two ends of the second refrigerant branch are respectively connected to the first refrigerant circuit between the first refrigerant branch and the second heat exchanger and a second refrigerant circuit between the first refrigerant branch and the third heat exchanger; The first refrigerant circuit connecting the first refrigerant branch, the first compressor, the first heat exchanger, the second heat exchanger and the second refrigerant branch, the second refrigerant circuit connecting the second refrigerant branch, the third heat exchanger, the fourth heat exchanger, the second compressor, the second refrigerant circuit of the first refrigerant branch and the first refrigerant branch constitute the third refrigerant circuit; A first solenoid valve is provided on the first refrigerant branch, a second solenoid valve and the third throttling device are provided on the second refrigerant branch, a third solenoid valve is provided on the first refrigerant circuit between the first refrigerant branch and the second refrigerant branch, and a fourth solenoid valve is provided on the second refrigerant circuit between the first refrigerant branch and the second refrigerant branch; The step of “controlling the third refrigerant circuit to be connected and controlling the first refrigerant circuit and the second refrigerant circuit to be blocked in the normal heating mode” further includes: In normal heating mode, the first solenoid valve and the second solenoid valve are controlled to be opened, and the third solenoid valve and the fourth solenoid valve are controlled to be closed; The step of "in the ultra-low temperature heating mode, controlling the third refrigerant circuit to be blocked, and controlling the first refrigerant circuit and the second refrigerant circuit to be connected respectively" further includes: In the ultra-low temperature heating mode, the first solenoid valve and the second solenoid valve are controlled to be closed, and the third solenoid valve and the fourth solenoid valve are controlled to be opened; The step of “controlling the third refrigerant circuit to be connected and controlling the first refrigerant circuit to be blocked in the cooling mode” further includes: In cooling mode, the first solenoid valve and the second solenoid valve are controlled to be opened, and the third solenoid valve is controlled to be closed; The control method further comprises: In normal heating mode or cooling mode, the first throttling device and the second throttling device are controlled to be fully opened.

9. The air conditioner control method according to claim 8, characterized in that: The control method further comprises: In the cooling mode, the fourth solenoid valve is controlled to open.

10. The air conditioner control method according to claim 8, characterized in that: The reversing valve assembly includes a first four-way reversing valve and a second four-way reversing valve, the first four-way reversing valve includes a first d port, a first s port, a first c port and a first e port, the first d port is connected to the output end of the first compressor, the first s port is connected to the input end of the first compressor, the first c port is connected to the first refrigerant circuit between the first heat exchanger and the first compressor, the first e port is connected to the end of the first refrigerant branch away from the second compressor, the second four-way reversing valve includes a second d port, a second s port, a second c port and a second e port, the second d port is connected to the output end of the second compressor, the second s port is connected to the input end of the second compressor, the second c port is connected to the second refrigerant circuit between the second refrigerant branch and the first refrigerant branch, the second e port is connected to the second refrigerant circuit between the fourth heat exchanger and the second compressor, and the fourth solenoid valve is arranged between the first refrigerant branch and the second d port; The steps of "controlling the reversing valve assembly to make the refrigerant flow from the second compressor and / or the first compressor to the first heat exchanger" and "controlling the reversing valve assembly to make the refrigerant in the first refrigerant circuit flow from the first compressor to the first heat exchanger, and the refrigerant in the second refrigerant circuit flow from the second compressor to the third heat exchanger" further include: Control the first c port to be connected to the first d port, and the first e port to be connected to the first s port; control the second c port to be connected to the second d port, and the second e port to be connected to the second s port; The step of "controlling the action of the reversing valve assembly to make the refrigerant flow from the second compressor and / or the first compressor to the fourth heat exchanger" further includes: The first e port is controlled to be connected to the first d port, and the first c port is controlled to be connected to the first s port; the second e port is controlled to be connected to the second d port, and the second c port is controlled to be connected to the second s port.

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