Air conditioning system and control method thereof

Abstract

The invention provides an air conditioning system and a control method thereof.The air conditioning system comprises a compressor, a four-way reversing valve, an outdoor heat exchanger, a first throttling element, a second throttling element and an indoor heat exchanger and further comprises a first plate heat exchanger and a second plate heat exchanger; a first heat exchange flow path and a second heat exchange flow path are arranged in the first plate heat exchanger, a third heat exchange flow path and a fourth heat exchange flow path are arranged in the second plate heat exchanger, and the first heat exchange flow path is connected between the first throttling element and the third heat exchange flow path in series. The second heat exchange flow path is controllably connected between an outlet of the first heat exchange flow path and a second air supply port of the compressor in series, an outlet of the third heat exchange flow path is connected with the second throttling element in series, and the fourth heat exchange flow path can be connected between an outlet of the third heat exchange flow path and a first air supply port of the compressor in series. The refrigeration energy efficiency and the low-temperature heating capacity of the system can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of air conditioning, and particularly relates to an air conditioning system and a control method thereof. BACKGROUND

[0002] To solve the problem of insufficient low-temperature heating capacity, conventional multi-split air conditioners usually use intermediate subcooling and intermediate air supplement to improve the low-temperature heating capacity, but the intermediate air supplement is limited, and the low-temperature heating capacity is still limited. For example, in an environment of-40℃, the suction density decreases significantly, and the mass flow rate decreases. Even if the intermediate air supplement is increased, the heating capacity is still not significantly improved. In addition, due to the characteristics of multi-split air conditioners, such as more indoor units, longer pipelines, and large installation gap between indoor and outdoor units, the low-temperature heating startup efficiency is low, and the condenser subcooling degree is insufficient, resulting in serious capacity and energy efficiency decay. SUMMARY

[0003] Therefore, the present application provides an air conditioning system and a control method thereof, which can overcome the technical problems of the related art air conditioning system, such as the low-temperature heating capacity not being significantly improved, and the condenser subcooling degree being insufficient in the refrigeration working condition, resulting in serious capacity and energy efficiency decay.

[0004] To solve the above problems, the present application provides an air conditioning system, which comprises a compressor, a four-way valve, an outdoor heat exchanger, a first throttling element, a second throttling element, and an indoor heat exchanger connected in sequence to form a refrigerant circulation for heating and cooling. The compressor comprises a first cylinder and a second cylinder. The first cylinder has a first air supplement port, and the second cylinder has a second air supplement port. The air conditioning system further comprises a first plate heat exchanger and a second plate heat exchanger. The first plate heat exchanger has a first heat exchange flow path and a second heat exchange flow path, and the second plate heat exchanger has a third heat exchange flow path and a fourth heat exchange flow path. The first heat exchange flow path is connected in series between the first throttling element and the third heat exchange flow path. The second heat exchange flow path is controllably connected in series between the outlet of the first heat exchange flow path and the second air supplement port. The outlet of the third heat exchange flow path is connected in series with the second throttling element, and the fourth heat exchange flow path can be connected in series between the outlet of the third heat exchange flow path and the first air supplement port.

[0005] In some embodiments, the suction port of the compressor is in communication with a gas-liquid separator, and the fourth heat exchange flow path can also be connected in series between the outlet of the third heat exchange flow path and the inlet of the gas-liquid separator.

[0006] In some embodiments, the air conditioning system further comprises a three-way reversing valve having a charging state and a suction state, the three-way reversing valve being controllable to switch between the charging state and the suction state, and when the three-way reversing valve is in the charging state, the fourth heat exchange flow path is in communication with the first charging port, and when in the suction state, the fourth heat exchange flow path is in communication with the inlet of the gas-liquid separator.

[0007] In some embodiments, a third throttling element is connected in series on the pipeline between the second heat exchange flow path and the outlet of the first heat exchange flow path, and a fourth throttling element is connected in series on the pipeline between the fourth heat exchange flow path and the outlet of the third heat exchange flow path.

[0008] In some embodiments, the indoor heat exchangers are at least two, the number of the second throttling elements corresponds to the number of the indoor heat exchangers, and each of the second throttling elements is located at the side of each of the indoor heat exchangers in communication with the outdoor heat exchanger.

[0009] The present application also provides a control method of the air conditioning system as described above, comprising the following steps:

[0010] Obtaining the operation mode of the air conditioning system;

[0011] According to the obtained operation mode, adjusting the flow path of the four-way reversing valve, controlling the on-off of the second heat exchange flow path and the fourth heat exchange flow path, and adjusting the opening degree of the first throttling element and the second throttling element.

[0012] In some embodiments, when the operation mode is the refrigeration mode, the flow path of the four-way reversing valve is adjusted to switch so that the discharge port of the compressor is in communication with the outdoor heat exchanger, the suction port is in communication with the indoor heat exchanger, the second heat exchange flow path is controlled to be in communication with the second charging port, the fourth heat exchange flow path is controlled to be in communication with the gas-liquid separator, the opening degree of the first throttling element is controlled to be maximum, and the opening degree of the second throttling element is adapted to the operation state of the compressor.

[0013] In some embodiments, when the operation mode is the heating mode, the flow path of the four-way reversing valve is adjusted to switch so that the discharge port of the compressor is in communication with the indoor heat exchanger, the suction port is in communication with the outdoor heat exchanger, the second heat exchange flow path is controlled to be in communication with the second charging port, the fourth heat exchange flow path is controlled to be in communication with the first charging port, and the opening degree of the first throttling element and the second throttling element is adapted to the operation state of the compressor.

[0014] In some embodiments, after adjusting the flow path switching of the four-way reversing valve to make the exhaust port of the compressor communicate with the indoor heat exchanger and the suction port communicate with the outdoor heat exchanger, before controlling the second heat exchange flow path to communicate with the second supercharging port and the fourth heat exchange flow path to communicate with the first supercharging port, the second heat exchange flow path is first controlled to be disconnected from the second supercharging port and the fourth heat exchange flow path is controlled to communicate with the gas-liquid separator, until the exhaust temperature of the exhaust port of the compressor is higher than the preset temperature value T, then the second heat exchange flow path is controlled to communicate with the second supercharging port and the fourth heat exchange flow path is controlled to communicate with the first supercharging port.

[0015] In some embodiments, when the operating mode is the defrosting mode, the flow path switching of the four-way reversing valve is adjusted to make the exhaust port of the compressor communicate with the outdoor heat exchanger and the suction port communicate with the indoor heat exchanger, the second heat exchange flow path is controlled to be disconnected from the second supercharging port, the fourth heat exchange flow path is controlled to communicate with the gas-liquid separator, the opening degree of the first throttling element is controlled to be maximum, and the opening degree of the second throttling element is controlled to be minimum.

[0016] The air conditioning system and the control method thereof provided by the application have the following beneficial effects:

[0017] By arranging the first plate heat exchanger and the second plate heat exchanger in the air conditioning system, the refrigerant circulating in the system can be subcooled twice when the air conditioning system operates in the cooling mode, thereby improving the subcooling degree (dryness) of the refrigerant in the indoor heat exchanger, and significantly improving the energy efficiency of the compressor and the air conditioning system, which is especially suitable for the working condition that the connecting pipe between the indoor unit and the outdoor unit of the air conditioning system is long (for example, a multi-connected air conditioning system). When the air conditioning system operates in the heating mode, the supercharged refrigerant can be introduced into the corresponding supercharging port of the compressor after being superheated, which can avoid the occurrence of supercharging liquid hammering and significantly improve the heating capacity of the compressor and the air conditioning system in a low-temperature environment.

[0018] The fourth heat exchange flow path can also be switched to a state of communicating with the gas-liquid separator, that is, the fourth heat exchange flow path is switched between the supercharging state and the suction state by the three-way reversing valve. When the air conditioning system operates in the heating mode, the three-way reversing valve is in the supercharging state, which can form double supercharging for the compressor, effectively reduce the exhaust temperature of the exhaust port of the compressor in this mode, and improve the heating capacity. When the air conditioning system operates in a mode that does not require supercharging, such as the cooling mode, the defrosting mode, or even the initial stage of the heating mode, the three-way reversing valve is controlled to be in the suction state. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. The drawings in the following description are only exemplary, and other drawings can be obtained by the provided drawings without creative labor for those skilled in the art.

[0020] Figure 1 is a system principle schematic diagram of the air conditioning system of the embodiment of the present application;

[0021] Figure 2 is Figure 1 is a refrigerant flow state schematic diagram of the air conditioning system in the mode of running refrigeration in the figure, the colored line indicates that the corresponding pipeline has refrigerant flow, and the black line indicates that the corresponding pipeline does not flow refrigerant;

[0022] Figure 3 is Figure 1 is a refrigerant flow state schematic diagram of the air conditioning system in the mode of running refrigeration in the figure, the colored line indicates that the corresponding pipeline has refrigerant flow, and the black line indicates that the corresponding pipeline does not flow refrigerant;

[0023] Figure 4 is Figure 1 is a refrigerant flow state schematic diagram of the air conditioning system in the mode of running refrigeration in the figure, the colored line indicates that the corresponding pipeline has refrigerant flow, and the black line indicates that the corresponding pipeline does not flow refrigerant;

[0024] Figure 5 is Figure 1 is a refrigerant flow state schematic diagram of the air conditioning system in the mode of running refrigeration in the figure, the colored line indicates that the corresponding pipeline has refrigerant flow, and the black line indicates that the corresponding pipeline does not flow refrigerant;

[0025] Figure 6 is Figure 1 is an external structure schematic diagram of the compressor in the figure;

[0026] Figure 7 is Figure 6 is a refrigerant flow schematic diagram in the compressor in the figure.

[0027] The reference signs are:

[0028] 1, compressor; 2, four-way reversing valve; 3, outdoor heat exchanger; 4, first throttling element; 5, first plate heat exchanger; 51, first heat exchange flow path; 52, second heat exchange flow path; 6, third throttling element; 7, second plate heat exchanger; 71, third heat exchange flow path; 72, fourth heat exchange flow path; 8, fourth throttling element; 9, three-way reversing valve; 10, second throttling element; 11, indoor heat exchanger; 14, gas-liquid separator;

[0029] q1, first cylinder; q2, second cylinder;

[0030] a1, suction port; a2, first supplementary gas port; a3, second supplementary gas port; a4, exhaust port;

[0031] b1, first port; b2, second port; b3, third port; b4, fourth port;

[0032] s1, suction refrigerant; s2, first supplementary gas refrigerant; s3, second supplementary gas refrigerant; s4, exhaust refrigerant. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The following description of at least one exemplary embodiment is merely illustrative in nature and not intended to further limit the present application or its application or uses. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application.

[0034] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0035] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0036] In addition, it should be noted that the use of the terms "first", "second" and the like is merely intended to distinguish corresponding components, and does not have a special meaning unless otherwise stated. Therefore, it should not be understood as a limitation on the scope of protection of the present application.

[0037] With reference to Figures 1 to 7 According to an embodiment of the present application, an air conditioning system is provided, which comprises a compressor 1, a four-way reversing valve 2, an outdoor heat exchanger 3, a first throttling element 4, a second throttling element 10 and an indoor heat exchanger 11 connected in sequence to form a refrigerant circulation for cooling and heating. Specifically, as shown in Figure 1 The four-way reversing valve 2 comprises a first port b1, a second port b2, a third port b3 and a fourth port b4. The first port b1 is in communication with the indoor heat exchanger 11, the second port b2 is in communication with the suction port a1 of the compressor 1 via a gas-liquid separator 14, the third port b3 is in communication with the outdoor heat exchanger 3, and the fourth port b4 is in communication with the discharge port a4 of the compressor 1. When the air conditioning system needs to be in a cooling flow path, the first port b1 is controlled to be in communication with the second port b2, and the third port b3 is controlled to be in communication with the fourth port b4. When the air conditioning system needs to be in a heating flow path, the first port b1 is controlled to be in communication with the fourth port b4, and the second port b2 is controlled to be in communication with the third port b3. Specifically, as shown in Figure 6 The compressor 1 comprises a first cylinder q1 and a second cylinder q2. The first cylinder q1 has a first recharging port a2, and the second cylinder q2 has a second recharging port a3. That is, the compressor 1 is a double-recharging compressor. Further, as shown in Figure 7 In another preferred embodiment, the compressor 1 is a double-stage double-recharging compressor. In this case, the first cylinder q1 sucks in refrigerant for primary compression, and then discharges the refrigerant into the second cylinder q2 for secondary compression, and then discharges the refrigerant into the system circulation through the discharge port a4. The air conditioning system further comprises a first plate heat exchanger 5 and a second plate heat exchanger 7. The first plate heat exchanger 5 has a first heat exchange flow path 51 and a second heat exchange flow path 52, and the second plate heat exchanger 7 has a third heat exchange flow path 71 and a fourth heat exchange flow path 74. The first heat exchange flow path 51 is connected in series between the first throttling element 4 and the third heat exchange flow path 71. The second heat exchange flow path 52 is controllably connected in series between the outlet of the first heat exchange flow path 51 and the second recharging port a3. The outlet of the third heat exchange flow path 71 is connected in series with the second throttling element 10, and the fourth heat exchange flow path 72 can be connected in series between the outlet of the third heat exchange flow path 71 and the first recharging port a2.

[0038] In the technical solution, the first plate heat exchanger 5 and the second plate heat exchanger 7 are arranged in the air conditioning system, so that the refrigerant circulating in the system can be twice subcooled when the air conditioning system operates in the cooling mode, thereby improving the subcooling degree (dryness) of the refrigerant in the indoor heat exchanger 11, and the energy efficiency of the compressor and the air conditioning system can be significantly improved, which is especially suitable for the working condition that the length of the connecting pipe between the indoor unit and the outdoor unit of the air conditioning system is relatively long (for example, a multi-connected air conditioning system); and when the air conditioning system operates in the heating mode, the corresponding gas supplement refrigerant can be introduced into the corresponding gas supplement port of the compressor after being superheated, so that the gas supplement liquid impact phenomenon can be avoided, and the heating capacity of the compressor and the air conditioning system in the low-temperature environment can be significantly improved.

[0039] In some embodiments, the suction port a1 of the compressor 1 is communicated with the gas-liquid separator 14, and the fourth heat exchange flow path 72 can also be connected in series between the outlet of the third heat exchange flow path 71 and the inlet of the gas-liquid separator 14. Specifically, the air conditioning system further comprises a three-way reversing valve 9 having a gas supplement state and a suction state, the three-way reversing valve 9 can be controlled to switch between the gas supplement state and the suction state, and when the three-way reversing valve 9 is in the gas supplement state, the fourth heat exchange flow path 72 is communicated with the first gas supplement port a2, and when the three-way reversing valve 9 is in the suction state, the fourth heat exchange flow path 72 is communicated with the inlet of the gas-liquid separator 14.

[0040] In the technical solution, the fourth heat exchange flow path 71 can also be switched to a state of being communicated with the gas-liquid separator 14, that is, the fourth heat exchange flow path 72 is switched between the gas supplement state and the suction state by the three-way reversing valve 9, when the air conditioning system operates in the heating mode, at this time, the three-way reversing valve 9 is in the gas supplement state, so that double gas supplement can be formed for the compressor 1, the exhaust temperature of the exhaust port a4 of the compressor 1 in this mode can be effectively reduced, and the heating capacity can be improved, and when the air conditioning system operates in a mode without gas supplement, such as the cooling mode, the defrosting mode, or even the stage when the heating mode is just started, the three-way reversing valve 9 is controlled to be in the suction state.

[0041] In some embodiments, a third throttling element 6 is connected in series on the pipeline between the second heat exchange flow path 52 and the outlet of the first heat exchange flow path 51, and a fourth throttling element 8 is connected in series on the pipeline between the fourth heat exchange flow path 72 and the outlet of the third heat exchange flow path 71. The first throttling element 4, the second throttling element 10, the third throttling element 6, and the fourth throttling element 8 can be electronic expansion valves.

[0042] In the technical solution, the control of the gas supplement refrigerant is realized by the on-off of the third throttling element 6 and the fourth throttling element 8, and of course, the opening degree of the third throttling element 6 and the fourth throttling element 8 can also be controlled to adjust the amount of the gas supplement refrigerant to match different temperature adjustment loads.

[0043] In some embodiments, there are at least two indoor heat exchangers 11, and the number of the second throttling elements 10 corresponds to the number of indoor heat exchangers 11 and is located on the side where each indoor heat exchanger 11 is connected to the outdoor heat exchanger 3. It can be understood that the air conditioning system is objectively a multi-split air conditioning system in this case.

[0044] According to an embodiment of the present invention, a control method for an air conditioning system as described above is also provided, comprising the following steps:

[0045] Obtain the operating mode of the air conditioning system;

[0046] Based on the obtained operating mode, adjust the flow path of the four-way reversing valve 2, control the on / off state of the second heat exchange flow path 52 and the fourth heat exchange flow path 72, and adjust the opening degree of the first throttling element 4 and the second throttling element 10.

[0047] In some implementation methods, see details. Figure 2 As shown, when the operating mode is cooling mode, the flow path switching of the four-way reversing valve 2 is adjusted so that the exhaust port a4 of the compressor 1 is connected to the outdoor heat exchanger 3 and the suction port a1 is connected to the indoor heat exchanger 11. The second heat exchange flow path 52 is controlled to be connected to the second air supply port a3 (that is, the third throttling element 6 is in the flow state in this state), and the fourth heat exchange flow path 72 is controlled to be connected to the gas-liquid separator 14 (that is, the fourth throttling element 8 is in the flow state in this state). The opening degree of the first throttling element 4 is controlled to be the maximum, and the opening degree of the second throttling element 10 is adapted to the compressor operating state. That is, the opening degree of the second throttling element 10 can be controlled normally.

[0048] Specifically, when the high-temperature and high-pressure gas discharged by the compressor 1 passes through the four-way valve 2 to reach the outdoor heat exchanger 3, the high-temperature and high-pressure liquid is cooled after passing through the heat exchanger, passes through the first throttling element 4 (at this time, the opening degree is adjusted to the maximum) and the first plate heat exchanger 5, wherein the first branch (that is, the flow path flowing into the second heat exchange flow path 52 described above, the same below) liquid refrigerant is throttled into a low-temperature and low-pressure liquid by the third throttling element 6, and the high-temperature and high-pressure liquid refrigerant of the main flow path (that is, the flow path in which the first heat exchange flow path 51 described above is located) is further cooled in the first plate heat exchanger 5 to increase the supercooling degree thereof, the low-temperature and low-pressure liquid of the first branch absorbs heat to become a low-temperature and low-pressure gas and then returns to the second gas supplement port a3 of the compressor 1, the liquid refrigerant of the main flow path is further supercooled and then passes through the second plate heat exchanger 7 to be further cooled, the second branch (that is, the flow path flowing into the fourth heat exchange flow path 72 described above, the same below) liquid refrigerant is throttled into a low-temperature and low-pressure liquid by the fourth throttling element 8, and the low-temperature and low-pressure gas is absorbed into the second plate heat exchanger 7 to complete the second branch cycle through the three-way valve 9 and the gas-liquid separator 14. The high-temperature and high-pressure liquid refrigerant of the main flow path passes through the long connecting pipe to reach the second throttling element 10 to be throttled and cooled into a low-temperature and low-pressure liquid, absorbs gas into a low-temperature and low-pressure gas after passing through the indoor heat exchanger 11, and then returns to the gas-liquid separator 14 through the four-way valve 2, and finally returns to the compressor 1, thereby realizing the deep supercooling gas supplement enthalpy increasing refrigeration cycle. It should be noted that in the traditional single-plate supercooling air conditioning system, the temperature difference of the refrigerant at the plate is about 15°C (that is, the supercooling degree), and in the double-plate supercooling air conditioning system adopting the present application, the supercooling degree after passing through the two plate exchanges is as high as 35°C, thereby realizing deep supercooling.

[0049] In some embodiments, referring specifically to Figure 4 When the operation mode is the heating mode, the flow path switching of the four-way valve 2 is adjusted to make the exhaust port a4 of the compressor 1 communicate with the indoor heat exchanger 11, and the suction port a1 communicate with the outdoor heat exchanger 3, the second heat exchange flow path 52 is controlled to communicate with the second gas supplement port a3, the fourth heat exchange flow path 72 is controlled to communicate with the first gas supplement port a2, and the opening degrees of the first throttling element 4 and the second throttling element 10 are adjusted to adapt to the operation state of the compressor.

[0050] Specifically, when the high-temperature, high-pressure gas discharged from compressor 1 reaches the indoor heat exchanger 11 through the four-way reversing valve 2 and the long connecting pipe, it is cooled into a high-temperature, high-pressure liquid. It then flows through the second throttling element 10 (with normal opening control) and is further cooled by the second plate heat exchanger 7. The second branch liquid refrigerant is throttled by the fourth throttling element 8 into a low-temperature, low-pressure liquid. It absorbs heat in the second plate heat exchanger 7, becoming a low-temperature, low-pressure gas. This gas then returns to the first gas inlet a2 in compressor 1 through the three-way reversing valve 9. The main stream refrigerant is further cooled and then passes through the first plate heat exchanger 5. The high-temperature, high-pressure liquid refrigerant in the flow path is further cooled. The first branch of liquid refrigerant is throttled by the third throttling element 6 into a low-temperature, low-pressure liquid. After absorbing heat in the first plate heat exchanger 5, the low-temperature, low-pressure liquid becomes a low-temperature, low-pressure gas and returns to the second gas injection port a3 of the compressor. The main flow of liquid refrigerant is further subcooled and throttled by the first throttling element 4 (at which point the opening is normally controlled) into a low-temperature, low-pressure liquid. After passing through the outdoor heat exchanger 3, it absorbs heat and becomes a low-temperature, low-pressure gas. Then, it passes through the four-way reversing valve 2 and returns to the gas-liquid separator 14, finally returning to the compressor 1, completing the multi-stage gas injection and enthalpy-increasing heating cycle. It is understandable that, based on the same cylinder volume, the refrigerant mass flow rate can be significantly increased, thereby increasing the heating capacity.

[0051] In some implementation methods, see details. Figure 3 As shown, after adjusting the flow path switching of the four-way reversing valve 2 to connect the exhaust port a4 of the compressor 1 with the indoor heat exchanger 11 and the suction port a1 with the outdoor heat exchanger 3, before controlling the connection of the second heat exchange flow path 52 with the second air supply port a3 and the fourth heat exchange flow path 72 with the first air supply port a2, the connection of the second heat exchange flow path 52 with the second air supply port a3 is first disconnected (that is, the third throttling element 6 is in the cut-off state), and the fourth heat exchange flow path 72 is connected with the gas-liquid separator 14, until the exhaust temperature of the exhaust port a4 of the compressor 1 is higher than the preset temperature value T (in a specific embodiment, T is 15°C), and then the connection of the second heat exchange flow path 52 with the second air supply port a3 and the fourth heat exchange flow path 72 with the first air supply port a2 is controlled. It should be noted that since the air conditioning system has just started operating in heating mode, controlling the second heat exchange flow path 52 to disconnect the gas supply can prevent gas supply liquid slugging. At the same time, controlling the fourth heat exchange flow path 72 to connect with the gas-liquid separator 14 can improve the quality of the intake refrigerant.

[0052] Specifically, when the high-temperature, high-pressure gas discharged from compressor 1 passes through the four-way reversing valve 2 and the long connecting pipe to the indoor heat exchanger 11, it is cooled into a high-temperature, high-pressure liquid. It then flows through the second throttling element 10 (with the opening normally controlled at this time) and passes through the second plate heat exchanger 7 for further cooling. The liquid refrigerant in the second branch is throttled into a low-temperature, low-pressure liquid by the fourth throttling element 8. It absorbs heat in the second plate heat exchanger 7 and becomes a low-temperature, low-pressure gas. It then enters the gas-liquid separator 14 through the three-way reversing valve 9. The refrigerant in the main stream is further cooled and then passes through the first plate heat exchanger 5 (with the third throttling element 6 (closed at this time) and no refrigerant passes through the first branch). The liquid refrigerant in the main stream is throttled into a low-temperature, low-pressure liquid by the first throttling element 4 (with the opening normally controlled at this time). It then absorbs heat in the outdoor heat exchanger 3 and becomes a low-temperature, low-pressure gas. It then returns to the gas-liquid separator 14 through the four-way reversing valve 2 and finally returns to compressor 1, completing the heating start-up heating cycle. It should be noted that this control step is for the air conditioning system starting up and operating in heating mode in a low-temperature environment. In this condition, at the beginning of the heating mode operation (i.e., low-temperature start-up), the amount of air intake is very small due to the flash evaporation of liquid refrigerant in the gas-liquid separator 14 and the outdoor heat exchanger 3. At this time, the refrigerant flowing out of the indoor heat exchanger 11 is diverted to the gas-liquid separator 14 and further guided to the suction port a1 of the compressor 1, which can increase the suction pressure, thereby increasing the suction volume and making the heating start-up faster.

[0053] In some implementation methods, see details. Figure 5 As shown, when the operating mode is defrosting mode, the flow path switching of the four-way reversing valve 2 is adjusted so that the exhaust port a4 of the compressor 1 is connected to the outdoor heat exchanger 3 and the suction port a1 is connected to the indoor heat exchanger 11. The second heat exchange flow path 52 is controlled to cut off the connection with the second air supply port a3, and the fourth heat exchange flow path 72 is controlled to connect with the gas-liquid separator 14. The opening degree of the first throttling element 4 is controlled to be the maximum and the opening degree of the second throttling element 10 is controlled to be the minimum.

[0054] Specifically, when the high-temperature and high-pressure gas discharged from compressor 1 reaches the outdoor heat exchanger 3 through the four-way reversing valve 2, it is cooled by defrosting in the heat exchanger and then passes through the first throttling element 4 (at which time the opening is adjusted to the maximum) and the first plate heat exchanger 5 and the second plate heat exchanger 7. The third throttling element 6 is in the closed state, and the fourth throttling element 8 is in normal control. There is no refrigerant circulation in the first branch. The second throttling element 10 is in the closed state, so the refrigerant cannot flow through the indoor unit. Therefore, the room will not absorb heat and cool down due to the low temperature of the defrosting pipe. After passing through the fourth throttling element 8, the second branch is throttled into a low-temperature and low-pressure liquid and flows through the second plate heat exchanger 7 and enters the vapor-liquid separator 14 through the three-way reversing valve 9, and finally returns to compressor 1.

[0055] Those skilled in the art can easily understand that the advantageous technical features of the above-mentioned modes can be freely combined and superimposed without conflict.

[0056] The above description is merely the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above description is merely the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An air conditioning system comprising a compressor (1), a four-way reversing valve (2), an outdoor heat exchanger (3), a first throttling element (4), a second throttling element (10), and an indoor heat exchanger (11) connected in series to form a refrigerant cycle for cooling and heating, characterized in that, The compressor (1) includes a first cylinder (q1) with a first air supplement port (a2) and a second cylinder (q2) with a second air supplement port (a3), and further includes a first plate heat exchanger (5) with a first heat exchange flow path (51) and a second heat exchange flow path (52) and a second plate heat exchanger (7) with a third heat exchange flow path (71) and a fourth heat exchange flow path (74), the first heat exchange flow path (51) is connected in series between the first throttling element (4) and the third heat exchange flow path (71), the second heat exchange flow path (52) is controllably connected in series between the outlet of the first heat exchange flow path (51) and the second air supplement port (a3), the outlet of the third heat exchange flow path (71) is connected in series with the second throttling element (10) and the fourth heat exchange flow path (72) can be connected in series between the outlet of the third heat exchange flow path (71) and the first air supplement port (a2).

2. The air conditioning system of claim 1, wherein, The suction port (a1) of the compressor (1) is communicated with a gas-liquid separator (14), and the fourth heat exchange flow path (72) can also be connected in series between the outlet of the third heat exchange flow path (71) and the inlet of the gas-liquid separator (14).

3. The air conditioning system of claim 2, wherein, A three-way reversing valve (9) is further included, which has an air supplement state and a suction state, can be controlled to switch between the air supplement state and the suction state, and when the three-way reversing valve (9) is in the air supplement state, the fourth heat exchange flow path (72) is communicated with the first air supplement port (a2), and when in the suction state, the fourth heat exchange flow path (72) is communicated with the inlet of the gas-liquid separator (14).

4. The air conditioning system of claim 2, wherein, A third throttling element (6) is connected in series on the pipeline between the second heat exchange flow path (52) and the outlet of the first heat exchange flow path (51), and a fourth throttling element (8) is connected in series on the pipeline between the fourth heat exchange flow path (72) and the outlet of the third heat exchange flow path (71).

5. The air conditioning system of claim 2, wherein, The indoor heat exchanger (11) has at least two, the number of the second throttling element (10) corresponds to the number of the indoor heat exchanger (11) and is respectively arranged on the side of each indoor heat exchanger (11) communicated with the outdoor heat exchanger (3).

6. A control method of an air conditioning system as claimed in any one of claims 3 to 5, characterized in that, The method comprises the following steps: Obtaining the operation mode of the air conditioning system; According to the obtained operation mode, adjusting the flow path of the four-way reversing valve (2), controlling the on-off of the second heat exchange flow path (52) and the fourth heat exchange flow path (72), and adjusting the opening degree of the first throttling element (4) and the second throttling element (10).

7. The control method according to claim 6, characterized by, When the operation mode is the cooling mode, the flow path switching of the four-way reversing valve (2) is adjusted to make the discharge port (a4) of the compressor (1) communicate with the outdoor heat exchanger (3), the suction port (a1) communicate with the indoor heat exchanger (11), control the second heat exchange flow path (52) to communicate with the second supercharging port (a3), and control the fourth heat exchange flow path (72) to communicate with the gas-liquid separator (14), and the opening degree of the first throttling element (4) is maximum, and the opening degree of the second throttling element (10) is adapted to the compressor operation state.

8. The control method according to claim 6, characterized by, When the operation mode is the heating mode, the flow path switching of the four-way reversing valve (2) is adjusted to make the discharge port (a4) of the compressor (1) communicate with the indoor heat exchanger (11), the suction port (a1) communicate with the outdoor heat exchanger (3), control the second heat exchange flow path (52) to communicate with the second supercharging port (a3), and control the fourth heat exchange flow path (72) to communicate with the first supercharging port (a2), and the opening degree of the first throttling element (4) and the second throttling element (10) is adapted to the compressor operation state.

9. The control method according to claim 8, characterized by, After the flow path switching of the four-way reversing valve (2) is adjusted to make the discharge port (a4) of the compressor (1) communicate with the indoor heat exchanger (11), and the suction port (a1) communicate with the outdoor heat exchanger (3), before the second heat exchange flow path (52) is controlled to communicate with the second supercharging port (a3), and the fourth heat exchange flow path (72) is controlled to communicate with the first supercharging port (a2), the second heat exchange flow path (52) is first controlled to be disconnected from the second supercharging port (a3), and the fourth heat exchange flow path (72) is controlled to communicate with the gas-liquid separator (14), and then the second heat exchange flow path (52) is controlled to communicate with the second supercharging port (a3), and the fourth heat exchange flow path (72) is controlled to communicate with the first supercharging port (a2) when the discharge temperature of the discharge port (a4) of the compressor (1) is higher than the preset temperature value T.

10. The control method according to claim 6, characterized by When the operation mode is the defrosting mode, the flow path switching of the four-way reversing valve (2) is adjusted to make the discharge port (a4) of the compressor (1) communicate with the outdoor heat exchanger (3), the suction port (a1) communicate with the indoor heat exchanger (11), control the second heat exchange flow path (52) to be disconnected from the second supercharging port (a3), and control the fourth heat exchange flow path (72) to communicate with the gas-liquid separator (14), and the opening degree of the first throttling element (4) is maximum, and the opening degree of the second throttling element (10) is minimum.

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