A semi-hermetic single-unit two-stage screw compressor

Abstract

This utility model relates to a semi-hermetic single-unit two-stage screw compressor, comprising a casing, within which a motor, a first-stage rotor, and a second-stage rotor are sequentially arranged. The first-stage rotor includes a meshing first-stage male rotor and a first-stage female rotor, and the second-stage rotor includes a meshing second-stage male rotor and a second-stage female rotor. The casing includes, in sequence, a motor end cover, a motor housing, a first-stage exhaust housing, a rotor housing, a second-stage exhaust housing, and an exhaust end cover. The motor housing has an intake port, the rotor housing has an intercooler port for connecting an external intercooler, and the second-stage exhaust housing has an exhaust port. This utility model's semi-hermetic single-unit two-stage screw compressor features a novel structure, reasonable design, and good sealing, preventing refrigerant and lubricating oil leakage. It reduces overheating and leakage losses during compression, improves volumetric efficiency and isentropic efficiency, has a higher energy efficiency ratio, and improves the overall system efficiency.

Description

Technical Field

[0001] This utility model relates to the field of screw compressor technology, and in particular to a semi-hermetic single-unit two-stage screw compressor. Background Technology

[0002] The core of a screw compressor lies in the rotation of a pair of meshing helical rotors (screws) that complete the three continuous processes of intake, compression, and exhaust. Existing screw compressors suffer from the following problems: 1. Open-type single-unit two-stage screw compressors require a shaft seal at the drive shaft extension, but this seal structure is prone to leakage. Since many current mainstream refrigerants are toxic or can damage the ozone layer, leaks will lead to serious environmental pollution. 2. Semi-hermetic screw compressors mostly have only single-stage compression capability, but when the operating compression ratio of a semi-hermetic single-stage screw compressor exceeds 12, its operating efficiency will significantly decrease. 3. During compressor motor operation, current flows through the windings, generating heat; high temperatures can cause motor aging and affect its service life. 4. Under partial load operation, the compressor efficiency is low. Utility Model Content

[0003] In view of this, the purpose of this utility model is to provide a semi-hermetic single-unit two-stage screw compressor with good sealing performance, higher energy efficiency ratio, and improved overall compressor efficiency.

[0004] This utility model is implemented using the following scheme: a semi-hermetic single-unit two-stage screw compressor, including a housing, wherein a motor, a first-stage rotor, and a second-stage rotor are sequentially arranged inside the housing; the first-stage rotor includes a meshing first-stage male rotor and a first-stage female rotor, and the second-stage rotor includes a meshing second-stage male rotor and a second-stage female rotor; the housing includes a motor end cover, a motor housing, a first-stage exhaust housing, a rotor housing, a second-stage exhaust housing, and an exhaust end cover arranged sequentially, an intake port is provided on the motor housing, an intercooler port for connecting an external intercooler is provided on the rotor housing, and an exhaust port is provided on the second-stage exhaust housing.

[0005] Furthermore, the motor and the first-stage rotor are installed in the motor housing. The motor includes a motor stator and a motor rotor. A motor cooling sleeve is fitted outside the motor stator, and an annular cooling cavity is formed between the motor cooling sleeve and the motor housing. The air intake shaft of the first-stage male rotor extends into the middle of the motor rotor and is connected to the motor rotor by a key.

[0006] Furthermore, the motor housing is provided with a first oil port and a second oil port that are connected to the annular cooling cavity on the outside, and a third oil port that is connected to the second oil port through an oil pipe on the second stage exhaust housing. An oil flow switch is provided at the third oil port, and a lubricating oil passage that is connected to the third oil port is provided inside the housing.

[0007] Furthermore, the motor end cover is provided with a refrigerant nozzle that sprays refrigerant inward.

[0008] Furthermore, the inlet shaft of the first-stage male rotor is connected to a motor shaft end retaining ring by screws, and the motor shaft end retaining ring abuts against the inner end face of the motor rotor; a motor isolation sleeve is fitted on the inlet shaft of the first-stage male rotor, and the two ends of the motor isolation sleeve abut against the inner end face of the motor rotor and the shoulder on the inlet shaft of the first-stage male rotor, respectively.

[0009] Furthermore, the first-stage exhaust housing is provided with several capacity adjustment mechanisms. The capacity adjustment mechanism includes a plunger cavity, in which a capacity plunger is provided. One end of the plunger cavity is connected to the exhaust end of the first-stage rotor screw section, and the other end is connected to the low-pressure oil area and high-pressure oil area of ​​the compressor oil supply system through a pipeline and a solenoid valve. One end of the plunger cavity is provided with a spring seat that extends into the middle of the capacity plunger and slides with the capacity plunger. The spring seat is provided with a spring for pushing the capacity plunger to slide towards the other end. The motor housing is provided with a bypass cavity that connects one end of the plunger cavity and the intake cavity of the first-stage rotor intake end.

[0010] Furthermore, both the first-stage rotor and the second-stage rotor adopt an upper and lower arrangement structure, and the exhaust end shaft of the first-stage male rotor and the intake end shaft of the second-stage male rotor are connected by a coupling.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The semi-hermetic single-unit two-stage screw compressor of the present invention has a novel structure, reasonable design, and good sealing performance, avoiding refrigerant and lubricating oil leakage; it reduces overheating loss and leakage loss during the compression process, improves volumetric efficiency and isentropic efficiency, has a higher energy efficiency ratio, and improves the overall efficiency of the compressor; it has a good cooling effect on the motor and extends the service life of the motor.

[0012] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0013] Figure 1 This is a front view of an embodiment of the present utility model; Figure 2 yes Figure 1 BB section view; Figure 3 yes Figure 2 Sectional view of AA; Figure 4 yes Figure 2 CC section view; Figure 5 This is a partial rear view of an embodiment of the present utility model; The following are the labels in the diagram: 1-Refrigerant nozzle, 2-First-stage male rotor, 3-First-stage female rotor, 4-Second-stage male rotor, 5-Second-stage female rotor, 6-Motor end cover, 7-Motor housing, 8-First-stage exhaust housing, 9-Rotor housing, 10-Second-stage exhaust housing, 11-Exhaust end cover, 12-Inlet, 13-Intercooler inlet, 14-Exhaust port, 15-Motor stator, 16-Motor rotor, 17-Motor cooling jacket, 18-First oil port, 19-Second oil port, 20-Third oil port, 21-Oil flow switch, 22-Motor shaft end retaining ring, 23-Motor isolation sleeve, 24-Capacity adjustment mechanism, 25-Plunger cavity, 26-Capacity plunger, 27-Solenoid valve, 28-Spring seat, 29-Spring, 30-Bypass cavity, 31-Coupling. Detailed Implementation

[0014] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0015] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0016] like Figures 1-5 As shown, a semi-hermetic single-unit two-stage screw compressor includes a housing. Inside the housing, a motor 1, a first-stage rotor, and a second-stage rotor are sequentially arranged. The first-stage rotor includes a meshing first-stage male rotor 2 and a first-stage female rotor 3. The second-stage rotor includes a meshing second-stage male rotor 4 and a second-stage female rotor 5. The housing includes a motor end cover 6, a motor housing 7, a first-stage exhaust housing 8, a rotor housing 9, a second-stage exhaust housing 10, and an exhaust end cover 11 arranged sequentially. An intake port 12 is provided on the motor housing, an intercooler port 13 for connecting an external intercooler is provided on the rotor housing, and an exhaust port 14 is provided on the second-stage exhaust housing.

[0017] Low-pressure, low-temperature refrigerant gas from the evaporator enters the casing through the suction port. As the first-stage rotor meshes and rotates, the rotor slot volume continuously decreases, the gas is compressed, and the refrigerant, whose pressure and temperature rise to the intermediate pressure, is discharged from the exhaust port of the first-stage rotor. The refrigerant compressed by the first-stage rotor is drawn into the second-stage rotor, which performs a second compression on the refrigerant, and finally discharges it from the exhaust port.

[0018] The characteristics of the compression process (the volume of the compression chamber gradually decreases along the given axial direction of the rotor) allow for the installation of an additional suction port at a certain point after the compressor has completed suction, where the gas pressure is slightly increased. Therefore, introducing a certain proportion of extra gas into the intercooler port not only does not affect the suction volume but also provides an additional subcooling cycle to the refrigeration system. Because the increased subcooling significantly increases the cooling capacity, the system achieves a higher energy efficiency ratio. An intercooler is connected externally to the intercooler port, and the gas introduced into the intercooler port mixes with the already compressed gas before further compression.

[0019] In this embodiment, the motor 1 and the first-stage rotor are installed in the motor housing. The motor 1 includes a motor stator 15 and a motor rotor 16. A motor cooling sleeve 17 is fitted outside the motor stator. An annular cooling cavity is formed between the motor cooling sleeve and the motor housing. The air intake shaft of the first-stage male rotor extends into the middle of the motor rotor and is connected to the motor rotor by a key.

[0020] In this embodiment, the motor housing 7 is provided with a first oil port 18 and a second oil port 19 that are connected to the annular cooling cavity on the outside. The second-stage exhaust housing is provided with a third oil port 20 that is connected to the second oil port through an oil pipe. An oil flow switch 21 is provided at the third oil port. The motor housing is provided with a lubricating oil passage that is connected to the third oil port inside.

[0021] In this embodiment, the motor end cover is provided with a refrigerant nozzle 1 that sprays refrigerant inward, and there are two refrigerant nozzles 1, one long and one short.

[0022] The liquid cooling system consists of two parts: oil cooling and refrigerant liquid injection cooling. Oil cooling is used for external motor cooling. Compared to external water cooling, oil cooling has a longer service life, simpler operating conditions, better fluidity, and eliminates the need for anti-corrosion treatment of the motor housing. Lubricating oil enters the annular cooling chamber between the motor housing and the motor cooling jacket through the first oil port for heat exchange and cooling the motor. It then flows out from the second oil port along an oil pipe into the third oil port. The lubricating oil entering the third oil port reaches the oil flow switch. When the oil flow rate falls below a certain value, the oil flow switch issues an alarm, and the compressor stops to prevent the compressor from seizing and being damaged due to insufficient oil. After passing through the oil flow switch, the lubricating oil flows along the lubrication channels into the bearings, rotor, and inner cavity of the motor housing. Refrigerant liquid injection cooling is used for internal motor cooling. Liquid refrigerant from the condenser is sprayed out as liquid refrigerant through one refrigerant nozzle and as a mist of refrigerant through another refrigerant nozzle to cool the motor.

[0023] In this embodiment, a motor shaft end retaining ring 22 is screwed to the end of the air intake shaft of the first-stage male rotor, and the motor shaft end retaining ring abuts against the inner end face of the motor rotor. A motor isolation sleeve 23 is fitted on the air intake shaft of the first-stage male rotor, and the two ends of the motor isolation sleeve 23 abut against the inner end face of the motor rotor and the bearings (or shoulders on the air intake shaft of the first-stage male rotor) respectively, serving to position the motor and the first-stage male rotor. When the motor rotor rotates, the first-stage rotor meshes and rotates, driving the second-stage rotor to mesh and rotate. Bearings are respectively configured on the first-stage rotor and the second-stage rotor to provide support and improve the reliability of the system operation.

[0024] In this embodiment, the first-stage exhaust housing is provided with several capacity adjustment mechanisms 24. The capacity adjustment mechanism includes a plunger cavity 25, in which a capacity plunger 26 is provided. One end of the plunger cavity is connected to the exhaust end of the first-stage rotor screw section, and the other end is connected to the low-pressure oil area and high-pressure oil area of ​​the compressor oil supply system through a pipeline and a solenoid valve 27. One end of the plunger cavity is provided with a spring seat 28 that extends into the middle of the capacity plunger and slides with the capacity plunger. The spring seat is provided with a spring 29 for pushing the capacity plunger to slide towards the other end. The motor housing is provided with a bypass cavity 30 that connects one end of the plunger cavity and the intake cavity of the first-stage rotor intake end.

[0025] During loading, the solenoid valve is de-energized, and the other end of the plunger chamber 25 connects to the high-pressure oil zone. The capacity plunger, under the influence of the high-pressure oil, moves closer to the first-stage rotor. When the capacity plunger is pressed against the exhaust end face of the first-stage rotor screw section, the exhaust volume is at its maximum, indicating a full-load state. During unloading, the solenoid valve is energized, and the other end of the plunger chamber 25 connects to the low-pressure oil zone. The capacity plunger, under the influence of a spring, slides away from the first-stage rotor. When the capacity plunger is pressed against the other end face of the plunger chamber 25, the exhaust volume is at its minimum, and the load level is at its lowest. Three capacity adjustment mechanisms are provided in the first-stage exhaust housing, which can open or close the solenoid valves as needed to control the load level. When all three solenoid valves are de-energized and the capacity plunger is pressed against the exhaust end face of the first-stage rotor screw section, the exhaust volume is at its maximum, and the compressor is in a full-load state. When all three solenoid valves are energized and the capacity plunger is pressed against the other end face of the plunger chamber 25, the exhaust volume is at its minimum, and the compressor is in a state of lowest load. Using a plunger adjustment method saves space by eliminating the need for a slide valve structure, resulting in a more compact design.

[0026] In this embodiment, both the first-stage rotor and the second-stage rotor adopt an up-and-down arrangement structure, and the air outlet shaft of the first-stage male rotor and the air inlet shaft of the second-stage male rotor are connected by a coupling 31.

[0027] (1) It solves the shaft seal leakage problem of open-type single-unit two-stage screw compressors, avoids refrigerant and lubricating oil leakage, eliminates air and water, and prevents internal contamination of the compressor; (2) It divides the compression process into two stages (low-pressure stage and high-pressure stage). Compared with single-stage compressors operating at high pressure ratios, two-stage compression significantly reduces overheating and leakage losses during the compression process, improves volumetric efficiency and isentropic efficiency, and can still maintain high efficiency when the compression ratio reaches 12 or higher, solving the problem that single-stage compressors cannot maintain high efficiency under high compression ratios; (3) It adopts a combination of external oil cooling and internal refrigerant liquid injection cooling to cool the motor, extending the service life of the motor; (4) It adopts an intercooler and capacity adjustment mechanism to improve the overall efficiency of the compressor.

[0028] Unless otherwise stated, if any of the technical solutions disclosed in this utility model discloses a numerical range, then the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this utility model discloses only some numerical values ​​to illustrate the technical solutions of this utility model. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this utility model.

[0029] If this utility model discloses or relates to mutually fixedly connected parts or structural components, then unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured by integral molding using a casting process) (except where it is obviously impossible to use an integral molding process).

[0030] In addition, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in this utility model above include states or shapes that are similar to, close to, or approximate with them.

[0031] Any component provided by this utility model can be assembled from multiple individual components, or it can be a single component manufactured by a one-piece molding process.

[0032] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any other way. Any person skilled in the art may make changes or modifications to the disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model without departing from its technical solution shall still fall within the protection scope of this utility model.

Claims

1. A semi-hermetic single-motor two-stage screw compressor, characterized by: The device includes a housing, within which a motor, a first-stage rotor, and a second-stage rotor are sequentially arranged. The first-stage rotor includes a meshing first-stage male rotor and a first-stage female rotor, and the second-stage rotor includes a meshing second-stage male rotor and a second-stage female rotor. The housing includes a motor end cover, a motor housing, a first-stage exhaust housing, a rotor housing, a second-stage exhaust housing, and an exhaust end cover arranged sequentially. The motor housing has an intake port, the rotor housing has an intercooler port for connecting to an external intercooler, and the second-stage exhaust housing has an exhaust port.

2. Semi-hermetic single screw two-stage compressor according to claim 1, characterized in that: The motor and the first-stage rotor are installed in the motor housing. The motor includes a motor stator and a motor rotor. A motor cooling sleeve is fitted outside the motor stator. An annular cooling cavity is formed between the motor cooling sleeve and the motor housing. The air intake shaft of the first-stage male rotor extends into the middle of the motor rotor and is connected to the motor rotor by a key.

3. Semi-hermetic single screw two-stage compressor according to claim 2, characterized in that: The motor housing has a first oil port and a second oil port on its exterior, which are connected to the annular cooling chamber. The second-stage exhaust housing has a third oil port connected to the second oil port via an oil pipe. An oil flow switch is provided at the third oil port. The motor housing has a lubricating oil passage connected to the third oil port inside.

4. The semi-hermetic single-unit two-stage screw compressor according to claim 2, characterized in that: The motor end cover is equipped with a refrigerant nozzle that sprays refrigerant inward.

5. The semi-hermetic single-motor two-stage screw compressor according to claim 2, characterized in that: The first-stage male rotor has a motor shaft end retaining ring connected to its inlet shaft end by screws. The motor shaft end retaining ring abuts against the inner end face of the motor rotor. A motor isolation sleeve is fitted on the inlet shaft end of the first-stage male rotor. The two ends of the motor isolation sleeve abut against the inner end face of the motor rotor and the bearing or shoulder on the inlet shaft end of the first-stage male rotor, respectively.

6. The semi-hermetic single-motor two-stage screw compressor of claim 1, wherein: The first-stage exhaust housing is provided with several capacity adjustment mechanisms. Each capacity adjustment mechanism includes a plunger chamber, in which a capacity plunger is provided. One end of the plunger chamber is connected to the exhaust end of the first-stage rotor screw section, and the other end is connected to the low-pressure oil area and high-pressure oil area of ​​the compressor oil supply system through a pipeline and a solenoid valve. One end of the plunger chamber is provided with a spring seat that extends into the middle of the capacity plunger and slides with the capacity plunger. The spring seat is provided with a spring for pushing the capacity plunger to slide towards the other end. The motor housing is provided with a bypass cavity that connects one end of the plunger chamber and the intake chamber of the first-stage rotor intake end.

7. The semi-hermetic single-motor two-stage screw compressor of claim 1, wherein: Both the first-stage rotor and the second-stage rotor adopt an up-and-down arrangement structure. The exhaust shaft of the first-stage male rotor and the intake shaft of the second-stage male rotor are connected by a coupling.

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