An air-cooled screw heat pump system

Abstract

The utility model provides an air-cooled screw heat pump system, including a circulation main circuit, a compressor driver cooling branch circuit and a motor cooling branch circuit, wherein the circulation main circuit is used to realize heat exchange of refrigerant; the compressor driver cooling branch circuit is connected in parallel in the circulation main circuit, the compressor driver is connected in the compressor driver cooling branch circuit, and the compressor driver cooling branch circuit is used to take liquid from the circulation main circuit to form a cooling circuit of the compressor driver; the motor cooling branch circuit is connected between the compressor driver cooling branch circuit and the motor chamber of the compressor to form a cooling circuit of the compressor motor. The utility model can ensure that the inlet and outlet of the compressor driver cooling are always consistent with the system circulation, adopts a bypass pipeline and has a small resistance of the solenoid valve, can ensure the high efficiency of the unit performance, connects the compressor motor cooling branch circuit with the compressor driver cooling branch circuit, can ensure that the motor cooling liquid is always a supercooled liquid refrigerant, and the control is simple and convenient.

Description

Technical Field

[0001] The utility model belongs to the technical field of heat exchange systems, in particular to an air-cooled screw heat pump system. Background Art

[0002] The common variable frequency air-cooled screw compressor unit uses air cooling as the cooling method, but this type of cooling fan occupies a large area and has a capacity reduction problem at high ambient temperatures, which is not conducive to the efficient operation of the unit. The compressor driver using refrigerant cooling occupies a small area and does not have a capacity reduction problem, but it is necessary to ensure that the inlet and outlet pipes of the driver refrigerant cooling are consistent with the system refrigerant circulation direction, otherwise it will cause condensation inside the driver or poor heat dissipation.

[0003] For variable frequency air-cooled screw heat pump units, four one-way valves are often used to change the refrigerant flow direction of the system to ensure that the refrigerant flow direction in and out of the compressor driver is always consistent with the system. However, this method requires adding four piston / diaphragm one-way valves to the main circulation loop of the system, which is inconvenient for piping and the resistance of the one-way valve is usually between 20 and 60 kPa, which will seriously affect the heat exchange performance of the unit.

[0004] Furthermore, for the variable frequency air-cooled screw heat pump unit, the exhaust temperature is high when the pressure ratio is large and the water temperature is high, and the compressor motor needs to be cooled by liquid spray. The common liquid spray cooling is to take the refrigerant at the evaporator outlet liquid pipe of the main circulation loop and pass it to the compressor motor cavity. However, this form takes the refrigerant in the two-phase state after the valve during refrigeration, and cannot stably and continuously output the supercooled liquid refrigerant to ensure the cooling effect of the motor. Utility Model Content

[0005] In view of this, the utility model aims to provide an air-cooled screw heat pump system to solve the above technical problems.

[0006] In order to achieve the above object, the technical solution of the utility model is implemented as follows:

[0007] An air-cooled screw heat pump system comprises a circulation main circuit, a compressor driver cooling branch circuit and a motor cooling branch circuit, wherein the circulation main circuit is used to realize heat exchange of a refrigerant;

[0008] The main circulation path includes a compressor, a condensing coil, a gas-liquid separator, an evaporator and a four-way valve, wherein the compressor is connected to the compressor interface of the four-way valve through a pipeline; the condenser interface of the four-way valve is connected to the condensing coil through a pipeline; the condensing coil is connected to the evaporator through a pipeline; the evaporator is connected to the evaporator interface of the four-way valve through a pipeline; the separator interface of the four-way valve is connected to the gas-liquid separator through a pipeline, and the gas-liquid separator is connected to the compressor through a pipeline;

[0009] The press driver cooling branch is connected in parallel to the main circulation circuit, the press driver is connected to the press driver cooling branch, and the press driver cooling branch is used to take liquid from the main circulation circuit to form a cooling circuit for the press driver;

[0010] The motor cooling branch is connected between the compressor driver cooling branch and the motor chamber of the compressor to form a cooling circuit for the compressor motor;

[0011] A number of valves are provided in the air-cooled screw heat pump system to control the flow direction of the refrigerant in each circuit.

[0012] In a specific embodiment, the press driver cooling branch includes a first pipeline, a second pipeline, a third pipeline and a fourth pipeline.

[0013] One end of the first pipeline is connected to the main circulation path, and the other end is connected to the press driver; a fifth valve is installed at one end of the first pipeline close to the main circulation path, and a second valve is installed at one end of the first pipeline close to the press driver;

[0014] One end of the second pipeline is connected to the compressor driver, and the other end is connected to the circulation main line; a third valve and a seventh valve are installed on the second pipeline;

[0015] One end of the third pipeline is connected to the main circulation path, and the other end is connected to the second pipeline between the third valve and the seventh valve;

[0016] The fourth pipeline is connected between the first pipeline and the second pipeline.

[0017] In another specific embodiment, the press driver cooling branch includes a sixth pipeline, a seventh pipeline and an eighth pipeline.

[0018] One end of the sixth pipeline is connected to the main circulation path, and the other end is connected to the press driver; a sixth valve is installed at one end of the sixth pipeline close to the main circulation path, and a second valve is installed at one end of the sixth pipeline close to the press driver;

[0019] One end of the seventh pipeline is connected to the compressor driver, and the other end is connected to the gas-liquid separator, or is connected to the pipeline between the gas-liquid separator and the four-way valve; a third valve is installed at one end of the seventh pipeline close to the compressor driver, and a ninth valve is installed at one end of the seventh pipeline close to the gas-liquid separator;

[0020] One end of the eighth pipeline is connected to the sixth pipeline, and the other end is connected to the main circulation path; an eighth valve is installed on the eighth pipeline.

[0021] Furthermore, the motor cooling branch includes a fifth pipeline, one end of the fifth pipeline is connected to the first pipeline, and the other end is connected to the motor room of the compressor; a fourth valve and a one-way valve are installed on the fifth pipeline.

[0022] Furthermore, a first valve is installed on the pipeline between the condensing coil and the evaporator.

[0023] Furthermore, a first filter is installed on the pipeline between the condensing coil and the first valve.

[0024] Furthermore, a second filter is installed on the pipeline between the first valve and the evaporator.

[0025] Furthermore, a sight glass is installed on the pipeline between the first filter and the first valve to observe the state of the refrigerant.

[0026] Furthermore, the fifth valve is an electronic expansion valve.

[0027] Furthermore, the ninth valve is a solenoid valve.

[0028] Compared with the prior art, the air-cooled screw heat pump system described in the utility model has the following beneficial effects:

[0029] The air-cooled screw heat pump system described in the utility model controls the flow direction of the refrigerant by setting a valve, and takes liquid from the main circulation circuit to form a cooling circuit for the compressor driver and the compressor motor, ensuring that the inlet and outlet of the compressor driver cooling are always consistent with the system circulation, which is convenient for system piping, and at the same time adopts a bypass pipeline and a small solenoid valve resistance, which can ensure the high efficiency of the unit's performance, and connects the compressor motor cooling branch with the compressor driver cooling branch, which can ensure that the motor cooling liquid is always a supercooled liquid refrigerant and the control is simple and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the accompanying drawings:

[0031] Figure 1 This is a schematic diagram of the structure of the first embodiment of the utility model (the flow direction shown in the figure is the flow direction of the refrigerant in the refrigeration mode);

[0032] Figure 2 This is a schematic diagram of the structure of the first embodiment of the present utility model (the flow direction shown in the figure is the flow direction of the refrigerant in the heating mode);

[0033] Figure 3This is a schematic diagram of the structure of the second embodiment of the present utility model (the flow direction shown in the figure is the flow direction of the refrigerant in the refrigeration mode);

[0034] Figure 4 This is a schematic diagram of the structure of the second embodiment of the present invention (the flow direction shown in the figure is the flow direction of the refrigerant in the heating mode).

[0035] Description of reference numerals:

[0036] 1- compressor; 2- four-way valve; 3- condensing coil; 4- first filter; 5- sight glass; 6- first valve; 7- second filter; 8- evaporator; 9- gas-liquid separator; 10- second valve; 11- compressor driver; 12- third valve; 13- fourth valve; 14- one-way valve; 15- fifth valve; 16- sixth valve; 17- seventh valve; 18- eighth valve; 19- ninth valve; 20- first pipeline; 21- second pipeline; 22- third pipeline; 23- fourth pipeline; 24- fifth pipeline; 25- sixth pipeline; 26- seventh pipeline; 27- eighth pipeline. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0038] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0041] Embodiment 1

[0042] When the first valve 6 of the system pipeline is close to the press driver 11, the solution of this embodiment can be adopted, which is conducive to maintenance and saving pipeline costs.

[0043] The utility model provides an air-cooled screw heat pump system, such as Figure 1 , 2 As shown, it includes a circulation main circuit, which includes a compressor 1, a four-way valve 2, an evaporator 8, a first filter 4, a second filter 7, a first valve 6, a condensing coil 3 and a gas-liquid separator 9, and the above components are connected by pipelines. The four-way valve 2 includes a compressor interface, an evaporator interface, a condenser interface and a separator interface. The condenser interface of the four-way valve 2 is connected to the port of the condensing coil 3, and the other port of the condensing coil 3 is connected to the evaporator 8, and the evaporator 8 is connected to the evaporator interface of the four-way valve 2. The first filter 4, the first valve 6 and the second filter 7 are arranged in sequence on the pipeline between the condensing coil 3 and the evaporator 8. The air outlet of the compressor 1 is connected to the compressor interface of the four-way valve 2, the separator interface of the four-way valve 2 is connected to one end of the gas-liquid separator 9, and the other end of the gas-liquid separator 9 is connected to the air inlet of the compressor 1.

[0044] like Figure 1 As shown, the main circulation loop of the system in the refrigeration mode is: the high-temperature and high-pressure gas compressed by the compressor 1 flows through the four-way valve 2 into the condensing coil 3 to be cooled into liquid, and then the condensed liquid flows through the first filter 4 and the second filter 7 into the evaporator 8, and the condensed liquid exchanges heat with the outside air to achieve refrigeration. After the liquid is discharged from the evaporator 8, it flows into the evaporator interface of the four-way valve 2, and flows out from the separator interface of the four-way valve 2 into the gas-liquid separator 9, and the separated gas enters the suction port of the compressor 1.

[0045] like Figure 2As shown, the main circulation loop of the system in the heating mode is: the liquid medium is discharged from the compressor 1 into the compressor interface of the four-way valve 2, and flows into the evaporator 8 from the evaporator interface of the four-way valve 2 to be converted into a gaseous medium, and then passes through the second filter 7 and the first filter 4 to enter the condensing coil 3 for liquefaction, and finally the liquid medium enters the condenser interface of the four-way valve 2, and is discharged from the separator interface, and enters the air inlet of the compressor 1 after passing through the gas-liquid separator 9.

[0046] Furthermore, the compressor 1 is a variable frequency screw compressor, and the operating frequency is between 25 and 70 Hz. The condensing coil 3 is a finned tube heat exchanger with an axial flow fan, and the shape of the finned tube can be L-type / multi-V-type / U-type / inverted M-type. The compressor driver 11 is a refrigerant cooling driver with a heat dissipation backplane, and the backplane is provided with a refrigerant inlet and a refrigerant outlet pipe; the driver has a control program for detecting the backplane temperature, and can control the opening and adjustment ratio of the associated refilling valve, and the above control program is a prior art. The evaporator 8 is a dry evaporator.

[0047] like Figure 1 , 2 As shown, the main circulation circuit is also connected to a cooling branch of the press driver 11, which is used to connect the press driver 11 to form a cooling circuit of the press driver 11. The cooling branch of the press driver 11 includes a sixth valve 16, a second valve 10, a third valve 12 and a seventh valve 17, and each component is connected by a pipeline. One side of the press driver 11 is connected to the pipeline between the first filter 4 and the first valve 6 in the main circulation circuit through the first pipeline 20, and the sixth valve 16 is provided at one end of the first pipeline 20 close to the main circulation circuit, and the second valve 10 is provided at one end of the first pipeline 20 close to the press driver 11. The other side of the press driver 11 is connected to the pipeline between the first valve 6 and the second filter 7 in the main circulation circuit through the second pipeline 21, and the third valve 12 and the seventh valve 17 are provided at one end of the second pipeline 21 close to the press driver 11. The compressor driver 11 cooling branch is also provided with a third pipeline 22 and a fourth pipeline 23. The pipeline between the connection position of the first pipeline 20 and the circulation main circuit and the first filter 4 is connected to one end of the third pipeline 22, and the other end of the third pipeline 22 is connected to the second pipeline 21 between the third valve 12 and the seventh valve 17. The second pipeline 21 between the connection position of the second pipeline 21 and the circulation main circuit and the seventh valve 17 is connected to one end of the fourth pipeline 23, and the other end of the fourth pipeline 23 is connected to the first pipeline 20 between the sixth valve 16 and the second valve 10.

[0048] like Figure 1As shown, the cooling circuit of the compressor driver 11 in the refrigeration mode is: the cooling medium enters the first pipeline 20 from the main circulation path, flows through the sixth valve 16 and the second valve 10 in sequence, flows along the first pipeline 20 through the compressor driver 11 into the second pipeline 21, flows along the second pipeline 21 through the third valve 12 and the seventh valve 17 into the main circulation path.

[0049] like Figure 2 As shown, the cooling circuit of the compressor driver 11 in the heating mode is: the refrigerant flows from the main circulation circuit through the second pipeline 21 and the fourth pipeline 23 in sequence into the first pipeline 20, enters the compressor driver 11 through the second valve 10, flows out of the compressor driver 11 and flows through the third pipeline 22 into the main circulation circuit.

[0050] like Figure 1 , 2 As shown, the main circulation circuit is also connected to a motor cooling branch, which is used to connect to the motor room of the compressor 1 to form a motor cooling circuit. The motor cooling branch includes a fifth pipeline 24, one end of which is connected to the first pipeline 20 between the sixth valve 16 and the second valve 10, and the other end is connected to the motor room of the compressor 1. The fourth valve 13 and the one-way valve 14 are provided on the fifth pipeline 24.

[0051] Furthermore, a sight glass 5 is installed on the pipeline between the first valve 6 and the first filter 4 to bypass the first valve 6 and the first filter 4, so as to detect and observe the state of the refrigerant in the system.

[0052] Further, the first valve 6 may be preferably an electronic expansion valve, the second valve 10 and the third valve 12 may be preferably a manual angle valve or a manual ball valve, the fourth valve 13, the sixth valve 16 and the eighth valve 18 may be preferably a solenoid valve, and the fifth valve 15 and the seventh valve 17 may be preferably a solenoid valve or an electronic expansion valve. Among them, the fifth valve 15 is an electronic expansion valve, which can control the back plate temperature of the compressor driver 11 through the opening ratio to avoid condensation or poor cooling of the back plate.

[0053] Furthermore, the one-way valve 14 is a diaphragm type stainless steel one-way valve 14 .

[0054] like Figure 1 As shown, in the refrigeration mode, the cooling circuit of the motor of the compressor 1 is: the refrigerant flows from the main circulation path through the first pipeline 20 into the fifth pipeline 24, and enters the motor room of the compressor 1 along the fifth pipeline 24. In the refrigeration operation, the fifth valve 15 and the eighth valve 18 shall not be electrically closed; the sixth valve 16 and the seventh valve 17 shall be electrically opened; in this mode, the sixth valve 16 remains normally open, and when the seventh valve 17 is a solenoid valve, it maintains an intermittent open / closed state according to the back plate temperature of the compressor driver 11 to avoid condensation or poor cooling of the back plate; when the seventh valve 17 is an electronic expansion valve, it controls the back plate temperature of the compressor driver 11 through the opening ratio to avoid condensation or poor cooling of the back plate.

[0055] like Figure 2 As shown, in the heating mode, the cooling circuit of the motor of the compressor 1 is as follows: the refrigerant enters the second pipeline 21 from the main circulation path, flows through the second pipeline 21, the fourth pipeline 23 and the third pipeline 22 in sequence, and then enters the fifth pipeline 24, and enters the motor room of the compressor 1 along the fifth pipeline 24. In the heating operation, the sixth valve 16 and the seventh valve 17 shall not be electrically closed; the fifth valve 15 and the eighth valve 18 shall be electrically opened; in this mode, the eighth valve 18 remains normally open, and when the fifth valve 15 is a solenoid valve, it maintains an intermittent open / closed state according to the back plate temperature of the compressor driver 11 to avoid condensation or poor cooling of the back plate; when the fifth valve 15 is an electronic expansion valve, it controls the back plate temperature of the compressor driver 11 through the opening ratio to avoid condensation or poor cooling of the back plate.

[0056] Embodiment 2

[0057] The solution of this embodiment can be adopted when the system suction pipeline or the gas-liquid separator 9 is close to the compressor driver 11.

[0058] The utility model provides an air-cooled screw heat pump system, including a circulation main circuit, a compressor driver 11 cooling branch and a motor cooling branch, wherein the circulation main circuit has the same structure as the circulation main circuit provided in Example 1, and the system main circulation loop in the cooling mode and the heating mode is the same as that in Example 1, which will not be repeated here.

[0059] like Figure 3 , 4As shown, the difference between the cooling branch of the compressor driver 11 in this embodiment and the first embodiment is that the fifth valve 15 and the seventh valve 17 are cancelled, and the ninth valve 19 is added. The sixth pipeline 25, the seventh pipeline 26 and the eighth pipeline 27 are arranged in the cooling branch of the compressor driver 11. One end of the sixth pipeline 25 is connected to the pipeline between the first filter 4 and the first valve 6, and the other end is connected to the compressor driver 11. The second valve 10 is installed at the end of the sixth pipeline 25 close to the compressor driver 11, and the sixth valve 16 is installed at the end of the sixth pipeline 25 close to the circulation main line. The other side of the compressor driver 11 is connected to the seventh pipeline 26, and the other end of the seventh pipeline 26 is connected to the gas-liquid separator 9, or is connected to the pipeline between the four-way valve 2 and the gas-liquid separator 9. The third valve 12 is installed at the end of the seventh pipeline 26 close to the compressor driver 11, and the ninth valve 19 is installed at the end of the seventh pipeline 26 close to the gas-liquid separator 9. The sixth pipeline 25 between the sixth valve 16 and the second valve 10 is connected to the eighth pipeline 27, and the other end of the eighth pipeline 27 is connected to the pipeline between the first valve 6 and the second filter 7. The eighth valve 18 is installed on the eighth pipeline 27, and its function is to switch the flow direction of the cooling refrigerant entering the compressor driver 11 when the system switches between cooling and heating, so as to ensure that the inlet and outlet of the cooling refrigerant of the compressor driver 11 are always consistent with the system cycle.

[0060] Furthermore, a sight glass 5 is installed on the pipeline between the first valve 6 and the first filter 4 to bypass the first valve 6 and the first filter 4, so as to detect and observe the state of the refrigerant in the system.

[0061] Furthermore, the ninth valve 19 may preferably be a solenoid valve, which maintains an intermittent open / closed state according to the temperature of the back plate of the press driver 11 to avoid condensation or poor cooling of the back plate.

[0062] like Figure 3 As shown, the cooling circuit of the compressor driver 11 in the refrigeration mode is: the refrigerant enters the sixth pipeline 25 from the main circulation route, flows through the compressor driver 11 through the sixth pipeline 25, and then enters the seventh pipeline 26, and finally enters the gas-liquid separator 9, or enters the pipeline between the four-way valve 2 and the gas-liquid separator 9.

[0063] like Figure 4 As shown, the cooling circuit of the compressor driver 11 in the heating mode is: the refrigerant enters the sixth pipeline 25 from the main circulation route through the eighth pipeline 27, then flows through the compressor driver 11 into the seventh pipeline 26, and finally enters the gas-liquid separator 9, or enters the pipeline between the four-way valve 2 and the gas-liquid separator 9.

[0064] The motor cooling branch in this embodiment is the same as that in the first embodiment. The first pipeline 20 takes liquid from the main circulation circuit. The fifth pipeline 24 is connected between the first pipeline 20 and the compressor 1. The refrigerant flows through the first pipeline 20 into the fifth pipeline 24 and finally into the motor room of the compressor 1, forming a cooling circuit for the motor of the compressor 1.

[0065] In this embodiment, the cooling liquid return pipeline of the compressor driver 11 is the same pipeline, because it is discharged to the bottom of the gas-liquid separator 9 on the low-pressure side of the system, or it can be discharged to the middle pipeline between the four-way valve 2 and the gas-liquid separator 9 on the low-pressure side of the system. This approach can reduce the number of solenoid valves.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the utility model, and they should all be included in the scope of the claims and specification of the utility model.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An air-cooled screw heat pump system, characterized in that: It includes a circulation main circuit, a compressor driver cooling branch circuit and a motor cooling branch circuit, wherein the circulation main circuit is used to realize heat exchange of refrigerant; the circulation main circuit includes a compressor, a condensing coil, a gas-liquid separator, an evaporator and a four-way valve, wherein the compressor is connected to the compressor interface of the four-way valve through a pipeline; the condenser interface of the four-way valve is connected to the condensing coil through a pipeline; the condensing coil is connected to the evaporator through a pipeline; the evaporator is connected to the evaporator interface of the four-way valve through a pipeline; the separator interface of the four-way valve is connected to the gas-liquid separator through a pipeline. The compressor and the motor chamber of the compressor are connected by pipelines, and the gas-liquid separator is connected to the compressor through pipelines; the compressor driver cooling branch is connected in parallel in the main circulation circuit, and the compressor driver is connected to the compressor driver cooling branch, and the compressor driver cooling branch is used to take liquid from the main circulation circuit to form a cooling circuit for the compressor driver; the motor cooling branch is connected between the compressor driver cooling branch and the motor chamber of the compressor to form a cooling circuit for the compressor motor; a number of valves are arranged in the air-cooled screw heat pump system to control the flow direction of the refrigerant in each circuit.

2. The air-cooled screw heat pump system according to claim 1, characterized in that: The compressor driver cooling branch includes a first pipeline, a second pipeline, a third pipeline and a fourth pipeline, one end of the first pipeline is connected to the circulation main pipeline, and the other end is connected to the compressor driver; A fifth valve is installed at one end of the first pipeline close to the circulation main line, and a second valve is installed at one end of the first pipeline close to the press driver; one end of the second pipeline is connected to the press driver, and the other end is connected to the circulation main line; a third valve and a seventh valve are installed on the second pipeline; one end of the third pipeline is connected to the circulation main line, and the other end is connected to the second pipeline between the third valve and the seventh valve; the fourth pipeline is connected between the first pipeline and the second pipeline.

3. The air-cooled screw heat pump system according to claim 1, characterized in that: The compressor driver cooling branch includes a sixth pipeline, a seventh pipeline and an eighth pipeline, one end of the sixth pipeline is connected to the circulation main line, and the other end is connected to the compressor driver; a sixth valve is installed at one end of the sixth pipeline close to the circulation main line, and a second valve is installed at one end of the sixth pipeline close to the compressor driver; one end of the seventh pipeline is connected to the compressor driver, and the other end is connected to the gas-liquid separator, or to the pipeline between the gas-liquid separator and the four-way valve; a third valve is installed at one end of the seventh pipeline close to the compressor driver, and a ninth valve is installed at one end of the seventh pipeline close to the gas-liquid separator; one end of the eighth pipeline is connected to the sixth pipeline, and the other end is connected to the circulation main line; an eighth valve is installed on the eighth pipeline.

4. The air-cooled screw heat pump system according to claim 1, characterized in that: The motor cooling branch comprises a fifth pipeline, one end of which is connected to the first pipeline, and the other end of which is connected to the motor room of the compressor; a fourth valve and a one-way valve are installed on the fifth pipeline.

5. The air-cooled screw heat pump system according to claim 1, characterized in that: A first valve is installed on the pipeline between the condensing coil and the evaporator.

6. The air-cooled screw heat pump system according to claim 5, characterized in that: A first filter is installed on the pipeline between the condensing coil and the first valve.

7. The air-cooled screw heat pump system according to claim 5, characterized in that: A second filter is installed on the pipeline between the first valve and the evaporator.

8. The air-cooled screw heat pump system according to claim 6, characterized in that: A sight glass is installed in a bypass manner on the pipeline between the first filter and the first valve for observing the state of the refrigerant.

9. The air-cooled screw heat pump system according to claim 2, characterized in that: The fifth valve is an electronic expansion valve.

10. The air-cooled screw heat pump system according to claim 3, characterized in that: The ninth valve is a solenoid valve.

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