Low-temperature freezing screw compressor

Abstract

The utility model relates to the technical field of compressors, in particular to a low-temperature freezing screw compressor. The compressor comprises a first-stage compression mechanism and a second-stage compression mechanism. A first-stage motor, a first-stage male rotor, a first-stage female rotor, a first-stage slide valve, a first-stage loading oil inlet electromagnetic valve and a first-stage deloading oil discharge electromagnetic valve are arranged in the first-stage compression mechanism; a second-stage motor, a second-stage male rotor, a second-stage female rotor, a second-stage slide valve, a second-stage loading oil inlet electromagnetic valve and a second-stage deloading oil discharge electromagnetic valve are arranged in the second-stage compression mechanism; the two loading oil inlet solenoid valves and the two deloading oil discharge solenoid valves are controlled through pulses, so that the first-stage slide valve and the second-stage slide valve are controlled respectively, and real-time stepless adjustment of the two compression mechanisms is achieved. By arranging the two motors, the load of the motors can be better reduced, VI real-time stepless regulation of the compressor is achieved through the design of the sliding valve, the loading oil inlet electromagnetic valve and the deloading oil discharging electromagnetic valve, the operation efficiency of the compressor is improved, and energy consumption is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of compressors, in particular to a low-temperature refrigeration screw compressor. Background Art

[0002] Screw compressors are widely used in the field of refrigeration due to their simple structure, few wearing parts, ability to achieve low-temperature exhaust under large pressure difference or pressure ratio conditions, and good gas flow regulation. Vi can be adjusted continuously from 2.2 to 5.0 through the slider of the variable volume ratio, effectively adapting to the needs of various working conditions, avoiding over-compression or under-compression, and keeping the compressor running at the best efficiency and minimum vibration. It is currently widely used in refrigeration equipment such as freezing, refrigeration, air conditioning and chemical processes.

[0003] When a single-stage screw compressor is used in low-temperature refrigeration, the minimum saturated suction temperature is -50°C. If you want to break through this application limit, you need to use a two-stage or cascade system. In addition, when a single-stage compressor is used in a high-pressure ratio condition for low-temperature refrigeration, there will be the following problems. The lower the evaporation temperature, the higher the pressure ratio, the greater the pressure ratio and pressure difference between the unit volumes of the screw compressor, the greater the internal leakage, and the volumetric efficiency decreases. The lower the evaporation pressure, the greater the power consumption for producing refrigeration capacity, the lower the COP value of the system, the less compression, the greater the noise, and the higher the exhaust temperature.

[0004] Two-stage screw compressors solve the above problems very well. Compared with single-stage screw compressors, they have advantages such as high efficiency and high reliability. Compared with two-stage matching or cascade systems, they have advantages such as small footprint and simple control. Two-stage screw compressors have greatly broadened the application range of traditional single-screw compressors and piston compressors, and this product has dual internal volume ratio adjustment, suitable for more working conditions, and the lowest saturated suction temperature can reach -80℃.

[0005] Two-stage screw compressors usually use a motor shaft directly connected to the screw to drive the two-stage female and male rotors to rotate, and usually one motor drives the two-stage female and male rotors to rotate, such as a single-machine two-stage screw compressor disclosed in Chinese patent publication number CN217055586U. In this case, the motor load is large, the motor winding heats up seriously, and the compression efficiency is restricted.

[0006] On the other hand, the internal volume ratio is an important parameter of the screw compressor, which is closely related to the design and actual working conditions of the screw compressor. Due to the change of actual working conditions, the pressure at the end of compression in the screw compressor is often inconsistent with the pressure in the exhaust chamber, resulting in isochoric compression or isochoric expansion, which in turn increases additional power consumption. Utility Model Content

[0007] In order to solve the above-mentioned technical problems, the purpose of the utility model is to provide a low-temperature refrigeration screw compressor. By setting two motors, the motor load can be better reduced, and the design of the sliding valve, the loading oil inlet solenoid valve and the unloading oil unloading solenoid valve can realize real-time stepless adjustment of the VI of the compressor, improve the operating efficiency of the compressor, and reduce energy consumption.

[0008] In order to achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

[0009] A low-temperature refrigeration screw compressor, the compressor comprises a primary compression mechanism and a secondary compression mechanism fixedly connected to each other; the primary compression mechanism is provided with a primary motor, a primary slide valve, a primary loading oil inlet solenoid valve and a primary unloading oil unloading solenoid valve, and the secondary compression mechanism is provided with a secondary motor, a secondary slide valve, a secondary loading oil inlet solenoid valve and a secondary unloading oil unloading solenoid valve;

[0010] By pulse controlling the first-stage loading oil inlet solenoid valve and the first-stage unloading oil unloading solenoid valve and the second-stage loading oil inlet solenoid valve and the second-stage unloading oil unloading solenoid valve, the first-stage slide valve and the second-stage slide valve are controlled respectively, so as to realize real-time stepless adjustment of the first-stage compression mechanism and the second-stage compression mechanism.

[0011] Preferably, the first-stage compression mechanism comprises a first-stage outer shell and the first-stage motor, the first-stage male rotor, the first-stage female rotor and the first-stage sliding valve arranged in the first-stage outer shell; the first-stage outer shell is externally connected to an intake stop valve, and a first-stage compression chamber, a first-stage intake chamber and a first channel are arranged inside the first-stage outer shell, the intake stop valve is communicated with the first-stage intake chamber, the first-stage sliding valve is slidingly connected in the first channel, the first-stage motor is arranged at the connection between the first-stage outer shell and the second-stage compression mechanism and is located in the middle of the compressor, and the first-stage male rotor and the first-stage female rotor are meshed with each other and arranged in the first-stage compression chamber, and the intake ends of both are fixedly connected to one end of the first-stage outer shell close to the first-stage intake chamber; wherein, the exhaust end of the first-stage female rotor is fixed in the first-stage outer shell, and the exhaust end of the first-stage male rotor is plugged into the first-stage motor.

[0012] Preferably, the secondary compression mechanism comprises a secondary outer shell and the secondary motor, secondary male rotor, secondary female rotor and secondary slide valve arranged in the secondary outer shell; the secondary outer shell is externally connected to an exhaust stop valve, and a secondary compression chamber, a secondary exhaust chamber and a second channel are arranged inside the secondary outer shell, the exhaust stop valve is communicated with the secondary exhaust chamber, the secondary slide valve is slidably connected in the second channel, the second motor is arranged at the connection between the second outer shell and the primary compression mechanism and is located in the middle of the compressor, and the secondary male rotor and the secondary female rotor are meshed with each other and arranged in the secondary compression chamber, and the suction ends of both are fixedly connected to one end of the secondary outer shell close to the secondary exhaust chamber; wherein the exhaust end of the secondary female rotor is fixed in the secondary outer shell, and the exhaust end of the secondary male rotor is plugged into the secondary motor.

[0013] Preferably, the first-stage outer shell includes a first-stage motor shell, a first-stage bearing seat and a first-stage fuselage, and one end of the first-stage motor shell is bolted to connect the first-stage bearing seat and the first-stage fuselage in sequence; wherein, the first-stage compression chamber, the first-stage suction chamber and the first channel are all arranged in the first-stage fuselage, and the suction stop valve is fixedly arranged on the first-stage fuselage, and an air supply stop valve is fixedly arranged on the first-stage bearing seat.

[0014] Preferably, the secondary outer shell includes a secondary body and a secondary bearing seat, one end of the secondary body is fixedly connected to the other end of the primary motor housing, and the other end of the secondary body is fixedly connected to the secondary bearing seat; wherein the secondary compression chamber, the secondary exhaust chamber and the second channel are all arranged in the secondary bearing seat, and the exhaust stop valve is fixedly arranged on the secondary bearing seat.

[0015] Preferably, the first-stage body is provided with a first-stage pressure regulating chamber, a first-stage oil inlet hole and a first-stage oil outlet hole, the first-stage pressure regulating chamber and the first-stage slide valve are both arranged in the first channel, and the space size of the first-stage pressure regulating chamber is controlled by moving the first-stage slide valve; the first-stage pressure regulating chamber is located on the left side of the first-stage slide valve; the first-stage oil inlet hole and the first-stage oil outlet hole are arranged at the left end of the first-stage body and are connected to the first-stage pressure regulating chamber; wherein, the first-stage loading oil inlet solenoid valve is connected to the first-stage oil inlet hole, and the first-stage unloading oil solenoid valve is connected to the first-stage oil outlet hole.

[0016] Preferably, the secondary bearing seat is provided with a secondary pressure regulating chamber, a secondary oil inlet hole and a secondary oil outlet hole; the secondary pressure regulating chamber and the slide valve are both arranged in the second channel, and the space size of the secondary pressure regulating chamber is controlled by moving the secondary slide valve; the secondary pressure regulating chamber is located on the left side of the secondary slide valve; the secondary oil inlet hole and the secondary oil outlet hole are arranged at the left end of the secondary fuselage and are connected to the secondary pressure regulating chamber; wherein, the secondary loading oil inlet solenoid valve is connected to the secondary oil inlet hole, and the secondary unloading oil solenoid valve is connected to the secondary oil outlet hole.

[0017] Preferably, a junction box is provided on the outer diameter of the primary motor housing.

[0018] Preferably, a first-stage motor liquid spray port is provided on the outer diameter of the first-stage motor housing.

[0019] Preferably, a secondary motor spray port is provided on the outer diameter of the secondary bearing seat.

[0020] In summary, the advantages of the utility model are as follows:

[0021] 1. This compressor is provided with two motors to drive the corresponding compression mechanism to move respectively, so as to reduce the load of the motor, and further cool the motor through the unidirectional flow of refrigerant or liquid spray to ensure stable operation of the motor.

[0022] 2. This compressor is equipped with a content volume ratio adjustment mechanism in each stage of the compression mechanism. The adjustment mechanism cancels the design of fixed VI and can directly control the position of the slide valve by loading the oil inlet solenoid valve and unloading the oil unloading solenoid valve, so as to better adjust the content volume ratio, adapt to different working conditions, improve the operating efficiency of the compressor and reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the compressor;

[0024] Figure 2 is a schematic diagram of the back structure of the compressor;

[0025] Figure 3 is a first cross-sectional view of the compressor;

[0026] Figure 4 is a second cross-sectional view of the compressor;

[0027] Figure 5 It is a schematic diagram of the cross-sectional structure of the first-stage slide valve, the first-stage oil inlet hole and the first-stage oil outlet hole;

[0028] Figure 6 It is a cross-sectional structural schematic diagram of the secondary slide valve, the secondary oil inlet hole and the secondary oil outlet hole;

[0029] Figure numerals: 1, first-stage compression mechanism; 2, second-stage compression mechanism; 3, junction box; 4, first-stage motor liquid injection port; 5, second-stage motor liquid injection port; 11, first-stage loading oil inlet solenoid valve; 12, first-stage unloading oil solenoid valve; 21, second-stage loading oil inlet solenoid valve; 22, second-stage unloading oil solenoid valve; 101, first-stage outer shell; 102, first-stage motor; 103, first-stage male rotor; 104, first-stage female rotor; 105, first-stage slide valve; 106, suction stop valve; 107, first-stage compression chamber; 108, first-stage suction chamber; 109, first channel; 110, first-stage motor housing; 111. First-stage bearing seat; 112. First-stage fuselage; 113. Air supply stop valve; 121. First-stage pressure regulating chamber; 122. First-stage oil inlet hole; 123. First-stage oil outlet hole; 201. Second-stage outer shell; 202. Second-stage motor; 203. Second-stage male rotor; 204. Second-stage female rotor; 205. Second-stage slide valve; 206. Exhaust stop valve; 207. Second-stage compression chamber; 208. Second-stage exhaust chamber; 209. Second passage; 210. Second-stage fuselage; 211. Second-stage bearing seat; 221. Second-stage pressure regulating chamber; 222. Second-stage oil inlet hole; 223. Second-stage oil outlet hole. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0032] It should also be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0033] The specific implementation of the utility model is described in detail below in conjunction with the accompanying drawings.

[0034] like Figures 1 to 6As shown, a low-temperature refrigeration screw compressor includes a primary compression mechanism 1 and a secondary compression mechanism 2 which are fixedly connected to each other, and each of the primary compression mechanism 1 and the secondary compression mechanism 2 is provided with a motor, which can respectively drive the corresponding compression mechanism to move, reduce the motor load, and further cool the motor through the unidirectional flow of refrigerant or liquid spray to ensure stable operation of the motor.

[0035] Compared with the two-stage or cascade system, this compressor has the advantages of small footprint and simple control. It is completed by two compressions from the first-stage compression mechanism 1 to the second-stage compression mechanism 2. The gas transmission coefficient is higher than that of a single-stage compressor. At the same time, the pressure ratio of each stage is reduced, and the exhaust temperature is relatively low, which is suitable for working under large pressure ratio conditions.

[0036] On the basis of the existing technical solution, the compressor cancels other fixed VI designs and adopts two solenoid valves, namely, the loading oil inlet solenoid valve and the unloading oil unloading solenoid valve, to control the amount of refrigeration oil in the slide valve cavity through pulse control, thereby realizing the positioning of the slide valve at different axial positions, and correspondingly, finally realizing the control of different VIs of the compressor, so that it can adapt to more working conditions and improve the performance of the compressor. The two solenoid valves, namely, the loading oil inlet solenoid valve and the unloading oil unloading solenoid valve, are provided on both the first-stage compression mechanism 1 and the second-stage compression mechanism 2, and the specific structure will be described later.

[0037] Specifically, Figures 1 to 6 As shown, the first-stage compression mechanism 1 includes a first-stage outer shell 101 and a first-stage motor 102, a first-stage positive rotor 103, a first-stage negative rotor 104 and a first-stage sliding valve 105 arranged in the first-stage outer shell 101; an air intake stop valve 106 is externally connected to the outside of the first-stage outer shell 101, and a first-stage compression chamber 107, a first-stage suction chamber 108 and a first channel 109 are arranged inside the first-stage outer shell 101; wherein, the air intake stop valve 106 is communicated with the first-stage suction chamber 108, the first-stage sliding valve 105 is slidably connected in the first channel 109, the first-stage motor 102 is arranged at the connection between the first-stage outer shell 101 and the second-stage compression mechanism 2 and is located in the middle of the compressor, and the first-stage positive rotor 103 and the first-stage negative rotor 104 are meshed with each other and arranged in the first-stage compression chamber 107, and the suction ends of both are fixedly connected to one end of the first-stage outer shell 101 close to the first-stage suction chamber 108. The exhaust end of the first-stage female rotor 104 is fixed in the first-stage outer shell 101 , and the exhaust end of the first-stage male rotor 103 is plugged into the first-stage motor 102 .

[0038] The two-stage compression mechanism 2 includes a two-stage outer shell 201 and a two-stage motor 202, a two-stage male rotor 203, a two-stage female rotor 204 and a two-stage slide valve 205 arranged in the two-stage outer shell 201; an exhaust stop valve 206 is externally connected to the outside of the two-stage outer shell 201, and a two-stage compression chamber 207, a two-stage exhaust chamber 208 and a second channel 209 are arranged inside the two-stage outer shell 201; wherein the exhaust stop valve 206 is communicated with the two-stage exhaust chamber 208, the two-stage slide valve 205 is slidably connected in the second channel 209, the two-stage motor 202 is arranged at the connection between the two-stage outer shell 201 and the one-stage compression mechanism 1 and is located in the middle of the compressor, and the two-stage male rotor 203 and the two-stage female rotor 204 are meshed with each other and arranged in the two-stage compression chamber 207, and the suction ends of both are fixedly connected to one end of the two-stage outer shell 201 close to the two-stage exhaust chamber 208. The exhaust end of the secondary female rotor 204 is fixed in the secondary outer shell 201 , and the exhaust end of the secondary male rotor 203 is plugged into the secondary motor 202 .

[0039] A first-stage loading oil inlet solenoid valve 11 and a first-stage load-reducing oil unloading solenoid valve 12 connected to the first channel 109 are arranged outside the first-stage compression mechanism 1, and a second-stage loading oil inlet solenoid valve 21 and a second-stage load-reducing oil unloading solenoid valve 22 connected to the second channel 209 are arranged outside the second-stage compression mechanism 2; the first-stage loading oil inlet solenoid valve 11 and the first-stage load-reducing oil unloading solenoid valve 12 and the second-stage loading oil inlet solenoid valve 21 and the second-stage load-reducing oil unloading solenoid valve 22 are controlled by pulse control, thereby respectively controlling the first-stage slide valve 105 in the first channel 109 and the second-stage slide valve 205 in the second channel 209, thereby realizing real-time stepless adjustment of the first-stage compression mechanism 1 and the second-stage compression mechanism 2.

[0040] The two-stage dual-motor design can reduce the motor load and has an efficient heat dissipation system that enables the motor to operate stably under different working conditions; the two-stage dual-VI adjustment can make the compressor suitable for more working conditions and operate efficiently.

[0041] like Figures 1 to 5 As shown, the above-mentioned first-stage outer shell 101 includes a first-stage motor shell 110, a first-stage bearing seat 111 and a first-stage fuselage 112, and one end of the first-stage motor shell 110 is bolted to connect the first-stage bearing seat 111 and the first-stage fuselage 112 in sequence; wherein, the first-stage compression chamber 107, the first-stage suction chamber 108 and the first channel 109 are all arranged in the first-stage fuselage 112, and the suction stop valve 106 is fixedly arranged on the first-stage fuselage 112, and the air supply stop valve 113 is fixedly arranged on the first-stage bearing seat 111.

[0042] According to the above description, a first-stage pressure regulating chamber 121, a first-stage oil inlet hole 122 and a first-stage oil outlet hole 123 are provided on the first-stage body 112, and the first-stage pressure regulating chamber 121 and the first-stage slide valve 105 are both provided in the first channel 109, and the space size of the first-stage pressure regulating chamber 121 is controlled by moving the first-stage slide valve 105. Specifically, the first-stage pressure regulating chamber 121 is located on the left side of the first-stage slide valve 105, so the first-stage oil inlet hole 122 and the first-stage oil outlet hole 123 are provided at the left end of the first-stage body 112 and connected to the first-stage pressure regulating chamber 121. Among them, the first-stage loading oil inlet solenoid valve 11 is connected to the first-stage oil inlet hole 122, and the first-stage unloading oil solenoid valve 12 is connected to the first-stage oil outlet hole 123.

[0043] like Figures 1 to 6 As shown, the above-mentioned secondary outer shell 201 includes a secondary body 210 and a secondary bearing seat 211, one end of the secondary body 210 is fixedly connected to the other end of the primary motor housing 110, and the other end of the secondary body 210 is fixedly connected to the secondary bearing seat 211; wherein, the secondary compression chamber 207, the secondary exhaust chamber 208 and the second channel 209 are all arranged in the secondary bearing seat 211, and the exhaust stop valve 206 is fixedly arranged on the secondary bearing seat 211.

[0044] According to the above description, a secondary pressure regulating chamber 221, a secondary oil inlet hole 222 and a secondary oil outlet hole 223 are provided on the secondary bearing seat 211. The secondary pressure regulating chamber 221 and the slide valve are both provided in the second channel 209. The space size of the secondary pressure regulating chamber 221 is controlled by moving the secondary slide valve 205. The secondary pressure regulating chamber 221 is located on the left side of the secondary slide valve 205, while the secondary oil inlet hole 222 and the secondary oil outlet hole 223 are provided at the left end of the secondary fuselage 210 and are connected to the secondary pressure regulating chamber 221. Among them, the secondary loading oil inlet solenoid valve 21 is connected to the secondary oil inlet hole 222, and the secondary unloading oil solenoid valve 22 is connected to the secondary oil outlet hole 223.

[0045] In addition, if Figures 1 to 4 As shown, a junction box 3 is provided on the outer diameter of the primary motor housing 110, and a primary motor liquid spray port 4 and a secondary motor liquid spray port 5 are respectively provided on the outer diameter of the primary motor housing 110 and the outer diameter of the secondary bearing seat 211 for spraying liquid to cool the motor.

[0046] The above is a description of the embodiments of the utility model. Through the above description of the disclosed embodiments, professionals and technicians in the field can implement or use the utility model. Various modifications to these embodiments will be obvious to professionals and technicians in the field. The general principles defined in this article can be implemented in other embodiments without departing from the spirit or scope of the utility model. Therefore, the utility model will not be limited to these embodiments shown in this article, but will conform to the widest range consistent with the principles and novelties disclosed in this article.

Claims

1. A low-temperature refrigeration screw compressor, characterized in that: The compressor comprises a first-stage compression mechanism (1) and a second-stage compression mechanism (2) which are fixedly connected to each other; the first-stage compression mechanism (1) is provided with a first-stage motor (102), a first-stage slide valve (105), a first-stage loading oil inlet solenoid valve (11) and a first-stage unloading oil unloading solenoid valve (12); the second-stage compression mechanism (2) is provided with a second-stage motor (202), a second-stage slide valve (205), a second-stage loading oil inlet solenoid valve (21) and a second-stage unloading oil unloading solenoid valve (22); By pulse controlling the first-stage loading oil inlet solenoid valve (11) and the first-stage unloading oil discharge solenoid valve (12) and the second-stage loading oil inlet solenoid valve (21) and the second-stage unloading oil discharge solenoid valve (22), the first-stage slide valve (105) and the second-stage slide valve (205) are respectively controlled, thereby achieving real-time stepless regulation of the first-stage compression mechanism (1) and the second-stage compression mechanism (2).

2. A low-temperature refrigeration screw compressor according to claim 1, characterized in that: The first-stage compression mechanism (1) comprises a first-stage outer shell (101) and the first-stage motor (102), the first-stage male rotor (103), the first-stage female rotor (104) and the first-stage slide valve (105) arranged in the first-stage outer shell (101); the first-stage outer shell (101) is externally connected to an air suction stop valve (106), and the first-stage outer shell (101) is internally provided with a first-stage compression chamber (107), a first-stage air suction chamber (108) and a first channel (109); the air suction stop valve (106) is connected to the first-stage air suction chamber (108), and the first-stage slide valve (105) is slidably connected to the first channel ( 109), the first-stage motor (102) is arranged at the connection between the first-stage outer shell (101) and the second-stage compression mechanism (2) and is located in the middle of the compressor, and the first-stage male rotor (103) and the first-stage female rotor (104) are meshed with each other and arranged in the first-stage compression chamber (107), and the suction ends of both are fixedly connected to one end of the first-stage outer shell (101) close to the first-stage suction chamber (108); wherein the exhaust end of the first-stage female rotor (104) is fixed in the first-stage outer shell (101), and the exhaust end of the first-stage male rotor (103) is plugged into the first-stage motor (102).

3. A low-temperature refrigeration screw compressor according to claim 1, characterized in that: The two-stage compression mechanism (2) comprises a two-stage outer shell (201) and a two-stage motor (202), a two-stage male rotor (203), a two-stage female rotor (204) and a two-stage slide valve (205) arranged in the two-stage outer shell (201); the two-stage outer shell (201) is externally connected to an exhaust stop valve (206), and the two-stage outer shell (201) is internally provided with a two-stage compression chamber (207), a two-stage exhaust chamber (208) and a second channel (209); the exhaust stop valve (206) is connected to the two-stage exhaust chamber (208), and the two-stage slide valve (205) is slidably connected to the two-stage outer shell (201). A second motor is arranged in the second passage (209) at the connection between the second outer shell and the first-stage compression mechanism (1), and is located in the middle of the compressor, and the second-stage male rotor (203) and the second-stage female rotor (204) are meshed with each other and arranged in the second-stage compression chamber (207), and the suction ends of both are fixedly connected to one end of the second-stage outer shell (201) close to the second-stage exhaust chamber (208); wherein the exhaust end of the second-stage female rotor (204) is fixed in the second-stage outer shell (201), and the exhaust end of the second-stage male rotor (203) is plugged into the second-stage motor (202).

4. A low-temperature refrigeration screw compressor according to claim 2, characterized in that: The first-stage outer shell (101) comprises a first-stage motor shell (110), a first-stage bearing seat (111) and a first-stage body (112), wherein one end of the first-stage motor shell (110) is bolted to connect the first-stage bearing seat (111) and the first-stage body (112) in sequence; wherein the first-stage compression chamber (107), the first-stage suction chamber (108) and the first channel (109) are all arranged in the first-stage body (112), and the suction stop valve (106) is fixedly arranged on the first-stage body (112), and an air supply stop valve (113) is fixedly arranged on the first-stage bearing seat (111).

5. A low-temperature refrigeration screw compressor according to claim 3, characterized in that: The secondary outer shell (201) comprises a secondary body (210) and a secondary bearing seat (211), one end of the secondary body (210) is fixedly connected to the other end of the primary motor housing (110), and the other end of the secondary body (210) is fixedly connected to the secondary bearing seat (211); wherein the secondary compression chamber (207), the secondary exhaust chamber (208) and the second channel (209) are all arranged in the secondary bearing seat (211), and the exhaust stop valve (206) is fixedly arranged on the secondary bearing seat (211).

6. A low-temperature refrigeration screw compressor according to claim 4, characterized in that: The first-stage body (112) is provided with a first-stage pressure regulating chamber (121), a first-stage oil inlet hole (122) and a first-stage oil outlet hole (123); the first-stage pressure regulating chamber (121) and the first-stage slide valve (105) are both arranged in the first channel (109); the space size of the first-stage pressure regulating chamber (121) is controlled by moving the first-stage slide valve (105); the first-stage pressure regulating chamber (121) is located on the left side of the first-stage slide valve (105); the first-stage oil inlet hole (122) and the first-stage oil outlet hole (123) are arranged at the left end of the first-stage body (112) and are connected to the first-stage pressure regulating chamber (121); wherein the first-stage loading oil inlet solenoid valve (11) is connected to the first-stage oil inlet hole (122), and the first-stage unloading oil solenoid valve (12) is connected to the first-stage oil outlet hole (123).

7. A low-temperature refrigeration screw compressor according to claim 5, characterized in that: The secondary bearing seat (211) is provided with a secondary pressure regulating chamber (221), a secondary oil inlet hole (222) and a secondary oil outlet hole (223); the secondary pressure regulating chamber (221) and the slide valve are both arranged in the second channel (209); the space size of the secondary pressure regulating chamber (221) is controlled by moving the secondary slide valve (205); the secondary pressure regulating chamber (221) is located on the left side of the secondary slide valve (205); the secondary oil inlet hole (222) and the secondary oil outlet hole (223) are arranged at the left end of the secondary body (210) and are connected to the secondary pressure regulating chamber (221); wherein the secondary loading oil inlet solenoid valve (21) is connected to the secondary oil inlet hole (222), and the secondary unloading oil solenoid valve (22) is connected to the secondary oil outlet hole (223).

8. A low-temperature refrigeration screw compressor according to claim 4, characterized in that: A junction box (3) is provided on the outer diameter of the primary motor housing (110).

9. A low-temperature refrigeration screw compressor according to claim 4, characterized in that: A first-stage motor liquid spray port (4) is provided on the outer diameter of the first-stage motor housing (110).

10. A low-temperature refrigeration screw compressor according to claim 5, characterized in that: A secondary motor liquid spray port (5) is provided on the outer diameter of the secondary bearing seat (211).

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