Semi-closed double-screw compressor and compressor system

Abstract

The invention relates to the field of compressors, in particular to a semi-closed double-screw compressor and a compressor system.The semi-closed double-screw compressor comprises a motor arranged in an inner cavity in the front of a compressor shell and a compressor body arranged in an inner cavity in the rear of the compressor shell, a rotor of the motor is connected with a rotor of the compressor, and a motor cooling air inlet is formed in the front end of the compressor shell; a motor cooling channel is arranged in the motor and communicated with a compression chamber of the compressor through a motor cooling working medium channel arranged between the motor and the compressor body, and a compressor air inlet communicated with the compression chamber through a compressor air inlet channel is arranged on the compressor shell and located between the motor and the compressor body. According to the compressor, on the premise that the air suction efficiency of the compressor is guaranteed, efficient cooling of the motor is achieved.

Description

Technical Field

[0001] The present invention relates to the field of compressors, and in particular to a semi-enclosed twin-screw compressor and a compressor system. Background Art

[0002] The compressor is an important component of the refrigeration and heat pump system. The performance of the compressor directly affects the efficiency and power consumption of the system. The semi-hermetic screw compressor is a typical positive displacement compressor with an irreplaceable role. The semi-hermetic screw compressor combines the compressor body and the motor and installs them in the compressor housing. This structure enables the compressor to compress the gas stably and continuously while maintaining a high degree of sealing, thereby greatly improving the compression efficiency. In the design of the semi-hermetic screw compressor, the design of the air inlet and the air inlet channel is particularly important. Reasonable air inlet design and optimized air inlet channel can ensure that the gas enters the compressor smoothly, reduce air flow resistance, and improve air intake efficiency. This can not only reduce the energy consumption of the compressor, but also extend its service life.

[0003] At the same time, the layout of the air inlet also has an important impact on the piping layout of the compressor system. Reasonable air inlet layout can reduce the length of the pipeline and the number of elbows, reduce system resistance, and make the entire system more efficient and stable. On the other hand, the motor of the semi-hermetic screw compressor will generate a lot of heat when running at high speed, so effective cooling measures are required. This is not only to protect the motor from overheating damage, but also to ensure that the compressor can operate continuously and stably. It is worth noting that the economizer inlet flow of the current semi-hermetic screw compressor is relatively small. This is mainly due to the limitation of the rotor pitch, and the economizer inlet flow cannot be simply increased by increasing the cross-sectional area. This affects the efficiency of the compressor to a certain extent, which makes it have certain limitations in practical applications. In addition, existing screw compressors can usually only operate in a single system, and the system in which the compressor is located cannot be quickly switched. This makes the screw compressor inflexible in some occasions where the cooling capacity needs to be adjusted quickly.

[0004] In order to take into account both the heat dissipation of the motor and the air intake, the existing semi-enclosed screw compressor usually sets the air inlet at the end of the compressor. After the refrigerant enters the compressor through the air inlet, it first flows through the motor and takes away the heat generated by the operation of the motor before entering the compression chamber, and is discharged through the exhaust port after compression. The flow channels for the refrigerant to flow through the motor mainly include the flow channel set in the motor support space, the flow channel set in the stator cooling jacket, the gap between the stator and the rotor, and the flow channel set in the rotor. Among them, the large number of support structures set in the motor support space increases the flow resistance of the refrigerant. In order to increase the contact area between the refrigerant and the heat dissipation surface, the motor stator cooling jacket is provided with a large number of complex flow channel structures, which increases the flow resistance of the refrigerant. In addition, in order to improve the performance and efficiency of the motor, the gap between the stator and the rotor is usually extremely narrow, allowing only a small amount of refrigerant to flow through. The flow channel in the rotor moves at high speed with the rotor, and the refrigerant has a large resistance to flowing in and out of the flow channel. Therefore, the existing air intake channel structure for the refrigerant to flow through the motor will cause a large air intake resistance, affecting the air intake efficiency. In addition, due to the limitations of the air intake channel design and air intake method, the existing semi-hermetic screw compressor only has a single air intake in a single direction, which to a certain extent reduces the flexibility of the compressor system design and increases the complexity and flow resistance of the external air intake pipeline.

[0005] In terms of motor cooling, during the operation of the semi-hermetic screw compressor, the motor will generate a lot of heat. If the heat is not dissipated efficiently and in time, the compressor will not be able to operate stably. How to balance the compressor's intake efficiency, motor cooling efficiency and the convenience of pipeline layout is the key to the design of a semi-hermetic screw compressor. At present, there are several ways to cool the motor of a semi-hermetic screw compressor, including refrigerant cooling, coolant cooling, and lubricating oil cooling. Among them, the refrigerant cooling method allows the refrigerant to flow directly through the refrigerant channels inside and outside the motor, and the flow of the refrigerant takes away a large amount of heat generated by the operation of the motor. This method does not require an additional external cooling circulation system, which reduces the complexity of the system to a certain extent, but increases the refrigerant intake resistance and affects the compressor suction efficiency. Coolant cooling sets a cooling jacket outside the motor stator and sets an external heat dissipation cycle. The heat generated by the operation of the motor is taken away by the flow of coolant in the cooling jacket. This method has a good cooling effect and reduces the suction resistance of the compressor, but increases the complexity of the system and the operation and maintenance cost. In the case of lubricating oil cooling, lubricating oil channels are set up inside the motor stator and rotor, and the heat generated by the motor operation is removed by the flowing lubricating oil. This method does not require an additional external cooling circulation system and does not increase the suction resistance of the compressor. However, this method requires a large amount of lubricating oil supply, which places higher requirements on the lubricating oil pump and lubricating oil cooler, and increases the operation and maintenance cost of the system. In addition, a combination of multiple cooling methods is often used to achieve motor cooling. For example, a cooling jacket is set up outside the motor stator to remove the heat generated by the stator through the coolant, and a refrigerant channel is opened in the rotor to remove the heat generated by the rotor through the flow of the refrigerant. Therefore, how to balance the compressor's intake efficiency, motor cooling efficiency and the convenience of pipeline layout is the key to the design of semi-hermetic screw compressors. Summary of the invention

[0006] The object of the present invention is to provide a semi-enclosed twin-screw compressor and a compressor system, which can help to achieve efficient cooling of the motor while ensuring the suction efficiency of the compressor.

[0007] The technical solution of the present invention is: a semi-enclosed twin-screw compressor, comprising a motor arranged in the front inner cavity of the compressor housing and a compressor body in the rear inner cavity of the compressor housing, the rotor of the motor is connected to the compressor rotor, a motor cooling air inlet is arranged at the front end of the compressor housing, a motor cooling channel is arranged in the motor, and is connected to the compression chamber of the compressor through a motor cooling working medium channel arranged between the motor and the compressor body, and a compressor air inlet connected to the compression chamber through the compressor air inlet channel is arranged on the compressor housing between the motor and the compressor body.

[0008] Furthermore, the motor cooling channel includes motor rotor cooling channels arranged on the rotor of the motor at intervals along the circumferential direction, and a gap channel is formed between the rotor of the motor and the stator of the motor.

[0009] Furthermore, a stator cooling jacket is arranged on the outer side of the motor stator in the compressor housing, and a stator cooling channel is arranged on the stator cooling jacket.

[0010] Furthermore, a liquid collecting recess is provided on the lower side of the compressor housing between the motor and the compressor body, and a liquid drain port is provided on the side wall of the liquid collecting recess.

[0011] Furthermore, the liquid collecting recess is arranged at the lower side of the motor cooling medium channel; and a cooling medium air inlet chamber is formed in the compressor housing between the motor cooling air inlet and the motor.

[0012] Furthermore, the compressor housing is provided with compressor air inlets on both left and right sides of the upper portion between the motor and the compressor body, and the compressor housing is also provided with a compressor air inlet and liquid return port between the motor and the compressor body.

[0013] Furthermore, economizer air inlets communicating with the compression chamber are arranged on both sides of the rear portion of the compressor housing, and an exhaust port is arranged on the lower side of the rear end portion of the compressor housing.

[0014] Furthermore, a bearing seat structure for supporting a shaft portion of a compressor rotor is provided in a section of the compressor housing between the motor and the compressor body.

[0015] A semi-enclosed twin-screw compressor system includes a semi-enclosed twin-screw compressor, the economizer air inlet is connected to the evaporator, the compressor air inlet is connected to the economizer, the motor cooling air inlet is connected to the condenser outlet or the liquid storage outlet, the drain port is connected to the compressor air inlet and liquid return port via a drain branch path, a liquid pump, and a post-pump drain branch path, a liquid external discharge path is provided on the drain branch path and is connected to a drain valve, the exhaust port is connected to the liquid pump via a high-pressure gas path, and an exhaust path connected to a system oil separator is provided on the high-pressure gas path.

[0016] A semi-enclosed twin-screw compressor system includes a semi-enclosed twin-screw compressor, the economizer air inlet is connected to the evaporator, the compressor air inlet is connected to the economizer, the motor cooling air inlet is connected to the condenser outlet or the liquid storage outlet, the drain port is connected to the system oil separator via a drain branch path, a liquid pump, a post-pump drain branch path, and an exhaust path, the exhaust port is connected to the exhaust path, and a liquid discharge path is provided on the drain branch path and is connected to a drain valve.

[0017] Compared with the prior art, the present invention has the following advantages: 1. A compressor air inlet is set between the motor and the engine body to achieve low-pressure resistance suction. When the compressor is running, most of the refrigerant gas enters through the compressor air inlet. Since the flow path is shorter and there are fewer protrusions in the middle, a higher suction efficiency can be achieved. A motor cooling air inlet is set at the front of the motor. A small amount of refrigerant gas enters the compressor through the motor cooling air inlet. The heat generated during the operation of the motor is taken away by the refrigerant flowing through the motor, thereby achieving efficient heat dissipation and cooling of the motor while ensuring the suction efficiency of the compressor (low suction pressure loss). Since the compressor air inlet is set in the middle of the compressor, two compressor air inlets can be set in different directions. Any air inlet can be selected to connect to the system, or it can be connected to two different systems at the same time.

[0018] 2. Since the refrigerant gas may become liquid due to condensation when flowing in the semi-hermetic twin-screw compressor, in order to prevent the liquid refrigerant from entering the compression chamber and affecting the compression process, a liquid collecting recess is set at a low point between the motor and the compressor body, so that the liquid refrigerant will gather in the liquid collecting recess due to gravity, and when the liquid level reaches a certain height, it will be discharged from the compressor through the drain port to prevent liquid substances from accumulating in the compressor and affecting the normal use of the compressor.

[0019] 3. In addition, the present invention has two economizer inlets located on both sides of the compression chamber of the compressor. Any economizer inlet can be selected to be connected to the economizer of the system. The two economizer inlets can be connected to the economizer of a single system at the same time, and the two economizer inlets can be connected to the economizers of two different systems respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A three-dimensional view of a semi-hermetic twin-screw compressor of the present invention; Figure 2 is a front cross-sectional view of a semi-hermetic twin-screw compressor of the present invention; Figure 3 It is a front cross-sectional view of the refrigerant gas flow direction of the semi-hermetic twin-screw compressor of the present invention; Figure 4 A system diagram of a compressor system of the present invention; Figure 5 is a system diagram of another compressor system of the present invention; In the figure: 10-screw compressor; 20-motor; 201-motor stator; 202-motor rotor; 203-electrical box; 204-motor cooling air inlet; 205-stator cooling jacket; 206-gap channel; 207-motor rotor cooling channel; 208-motor cooling medium channel; 209-liquid collecting recess; 210-liquid drain port; 211-stator cooling channel; 212-cooling medium air inlet chamber; 30-compressor body; 301-compressor housing; 302-compressor Rotor; 303-compressor left air inlet; 304-compressor right air inlet; 305-compressor air inlet channel; 306-exhaust port; 307-left economizer inlet; 308-right economizer inlet; 309-compression chamber; 310-compressor air inlet and liquid return port; 311-bearing seat structure; 401-liquid pump; 402-drain valve; 501-drainage branch path; 502-pump rear drainage branch path; 503-high-pressure gas path; 504-exhaust path; 505-liquid discharge path. DETAILED DESCRIPTION

[0021] In order to make the above features and advantages of the present invention more understandable, embodiments are given below with reference to the accompanying drawings for detailed description, but the present invention is not limited thereto.

[0022] refer to Figures 1 to 5 A semi-enclosed twin-screw compressor 10 includes a motor 20 disposed in the front inner cavity of a compressor housing 301 and a compressor body 30 in the rear inner cavity of the compressor housing 301, a rotor 202 of the motor is connected to the compressor rotor 302, a motor cooling air inlet 204 is disposed at the front end of the compressor housing 301, a motor cooling channel is disposed in the motor 20, and is connected to the inlet of a compression chamber 309 of the compressor through a motor cooling medium channel 208 disposed between the motor 20 and the compressor body 30, and a compressor air inlet connected to the inlet of the compression chamber 309 through a compressor air inlet channel 305 is disposed on the compressor housing 301 between the motor 20 and the compressor body 30. The compressor air inlet is the main air inlet of the compressor, and most of the refrigerant gas enters the compressor body 30 through the compressor air inlet, and is then discharged through the compressor exhaust outlet after being compressed by the compressor body 30. Only a small part of the refrigerant gas enters the compressor through the motor cooling air inlet 204, flows through the motor cooling channel, enters the compressor body 30, and is discharged after being compressed by the compressor body. The refrigerant gas entering the compressor through the motor cooling air inlet 204 takes away a large amount of heat generated by the operation of the motor 20 when flowing through the motor cooling channel, thereby ensuring stable operation of the motor.

[0023] In this embodiment, the motor cooling channel includes motor rotor cooling channels 207 arranged on the motor rotor 202 at intervals along the circumferential direction, and a gap channel 206 is formed between the motor rotor 202 and the motor stator 201. A stator cooling jacket 205 is arranged outside the motor stator 201 in the compressor housing 301, and a stator cooling channel 211 is arranged on the stator cooling jacket 205.

[0024] In this embodiment, a liquid collecting recess 209 is provided on the compressor housing 301 at the lower side (low position) between the motor 20 and the compressor body 30, and a liquid drain port 210 connected to the outside is provided on the side wall of the liquid collecting recess 209, and the collected condensed liquid substances and other substances are discharged through the liquid drain port 210. The height of the liquid drain port 210 is higher than the bottom surface of the liquid collecting recess 209, and when the liquid level reaches a certain height, it is discharged from the compressor through the liquid drain port 210.

[0025] In this embodiment, the liquid collecting recess 209 is arranged at the lower side of the motor cooling medium channel 208; a cooling medium inlet chamber 212 is formed between the motor cooling air inlet 204 and the motor in the compressor housing 301, and the motor cooling air inlet 204 is arranged at the upper part of the compressor housing. An electrical box 203 is installed at the front end of the compressor housing 301 to control the motor.

[0026] In this embodiment, the compressor housing 301 is located between the motor 20 and the compressor body 30, and the upper left and right sides thereof are provided with compressor air inlets, which are respectively the compressor left air inlet 303 and the compressor right air inlet 304, so that most of the refrigerant gas enters the compressor from the compressor left air inlet 303 and the compressor right air inlet 304. The compressor left air inlet 303 and the compressor right air inlet 304 are located on the left and right sides of the compressor center of gravity, which can effectively reduce the weight of the pipelines of the external system and the shaking and vibration of the compressor caused by the impact of the fluid in the pipeline. The screw compressor can be connected to the system through any compressor air inlet, and the pipeline layout of the compressor system is facilitated by switching the compressor air inlet. The screw compressor can also switch the working state of the screw compressor by connecting the two compressor air inlets to different systems at the same time and switching the compressor air inlet in the working state through the external valve.

[0027] In this embodiment, the compressor housing 301 is located between the motor 20 and the compressor body 30 and is also provided with a compressor air inlet and liquid return port 310 .

[0028] In this embodiment, the rear part of the compressor housing 301 and both sides of the compression chamber 309 are provided with economizer air inlets, which are respectively the left economizer air inlet 307 and the right economizer air inlet 308. The refrigerant gas can also directly enter the compression chamber 309 from the left economizer inlet of the compressor 307 and the right economizer inlet of the compressor 308 to improve the efficiency of the compressor. An exhaust port 306 is provided at the lower side of the rear end of the compressor housing 301 to output the compressed gas.

[0029] In this embodiment, the compression chamber is arranged in a section of the compressor housing that matches the screw portion of the compressor rotor. A bearing seat structure 311 for supporting the shaft portion of the compressor rotor 302 is arranged in the section of the compressor housing 301 between the motor 20 and the compressor body 30, thereby providing support for the shaft portion of the compressor rotor 302.

[0030] Refrigerant flow path: The refrigerant gas entering the compressor from the left air inlet 303 and the right air inlet 304 of the compressor directly enters the compression chamber 309 through the compressor air inlet channel 305 with a short flow channel length and small flow resistance, thereby achieving a smaller compressor suction resistance. The refrigerant gas for cooling the motor 20 that enters the compressor from the motor cooling air inlet 204 flows into the gap channel 206, the motor rotor cooling channel 207 and the stator cooling channel 211 respectively, and takes away the heat generated by the motor stator 201 and the motor rotor 202 in the process of flowing through the motor 20, so as to maintain the stable and efficient operation of the motor. The refrigerant gas flowing through the motor rotor gap channel 206, the motor rotor cooling channel 207 and the stator cooling channel 211 is collected in the cavity between the motor 20 and the compressor body 30, and then enters the compression chamber 309 through the motor cooling medium channel 208. The refrigerant gas flowing into the compression chamber 309 is compressed by the rotating compressor rotor 302 and then discharged from the compressor through the exhaust port 306. The refrigerant gas entering from the left economizer inlet 307 and the right economizer inlet 308 directly flows into the compression chamber 309. In addition, the refrigerant gas may become liquid due to condensation when flowing in the semi-hermetic twin-screw compressor 10. In order to prevent the liquid refrigerant from entering the compression chamber 309 and affecting the compression process, a liquid collecting recess 209 is set at a low position between the motor 20 and the compressor body 30, so that the liquid refrigerant is collected in the liquid collecting recess 209 due to gravity, and when the liquid level reaches a certain height, it is discharged from the compressor through the drain port 210, thereby preventing the liquid substance from accumulating in the compressor and affecting the normal use of the compressor.

[0031] A semi-enclosed twin-screw compressor system includes a semi-enclosed twin-screw compressor 10, wherein a left economizer air inlet 307 and a right economizer air inlet 308 are connected to an evaporator, a left compressor air inlet 303 and a right compressor air inlet 304 are connected to an economizer, a motor cooling air inlet 204 is connected to a condenser outlet or a liquid storage outlet, the liquid discharge port 210 is connected to the compressor air inlet liquid return port 310 via a liquid discharge branch path 501, a liquid pump 401, and a post-pump liquid discharge branch path 502, a liquid external discharge path 505 is provided on the liquid discharge branch path 501 and is connected to a liquid discharge valve 402, the exhaust port 306 is connected to the liquid pump 401 via a high-pressure gas path 503, and an exhaust path 504 connected to a system oil separator is provided on the high-pressure gas path 503.

[0032] The liquid in the liquid discharge port 210 is extracted by the liquid pump 401, and the liquid is collected into the compressor air inlet and liquid return port 310 through the rear liquid discharge branch path 502 after the liquid pump 401 extracts the liquid. The liquid pump can be powered by a gas source or an electric source. When the liquid pump 401 is powered by a gas source, it is necessary to additionally connect the liquid pump 401 with the compressor exhaust port 306, and introduce the high-pressure refrigerant gas into the liquid pump 401 as a power source through the high-pressure gas path 503. The liquid substance and other substances in the liquid collecting recess 209 can be selected to be discharged to other containers through the liquid discharge valve 402.

[0033] A semi-enclosed twin-screw compressor system includes a semi-enclosed twin-screw compressor 10, wherein a left economizer air inlet 307 and a right economizer air inlet 308 are connected to an evaporator, a left compressor air inlet 303 and a right compressor air inlet 304 are connected to an economizer, a motor cooling air inlet 204 is connected to a condenser outlet or a liquid storage outlet, the drain port 310 is connected to a system oil separator via a drain branch path 501, a liquid pump 401, a post-pump drain branch path 502, and an exhaust path 504, the exhaust port 306 is connected to the exhaust path 504, and a liquid discharge path 505 is provided on the drain branch path 501 and is connected to a drain valve 402.

[0034] The liquid discharge port 210 is connected to the exhaust port 306, and together with the exhaust gas, is led into the system oil separator. A liquid pump 401 is provided at the outlet of the liquid discharge port 210 to pressurize the discharged liquid. The liquid discharge port 210 is connected to the liquid pump 401 through the liquid discharge branch path 501, and the pressurized discharged liquid is led into the exhaust path 504 through the post-pump liquid discharge branch path 502. In addition, the outlet of the liquid discharge port 210 is also connected to the liquid discharge valve 402 through the liquid discharge path 505, and the liquid substance and other substances in the liquid collecting recess 209 can be discharged into other containers through the liquid discharge valve 402.

[0035] The above description is only a preferred embodiment of the present invention. For ordinary technicians in this field, according to the teachings of the present invention, designing different forms of semi-enclosed twin-screw compressors and compressor systems does not require creative labor. Without departing from the principles and spirit of the present invention, all equal changes, modifications, substitutions and variations made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A semi-enclosed twin-screw compressor, comprising a motor disposed in the front inner cavity of a compressor housing and a compressor body in the rear inner cavity of the compressor housing, wherein the rotor of the motor is connected to the rotor of the compressor, and characterized in that: A motor cooling air inlet is arranged at the front end of the compressor housing, a motor cooling channel is arranged in the motor, and is connected to the compression chamber of the compressor via a motor cooling working medium channel arranged between the motor and the compressor body, and a compressor air inlet is arranged on the compressor housing between the motor and the compressor body and is connected to the compression chamber via the compressor air inlet channel.

2. A semi-hermetic twin-screw compressor according to claim 1, characterized in that: The motor cooling channel comprises motor rotor cooling channels which are arranged on the rotor of the motor at intervals along the circumferential direction, and a gap channel is formed between the rotor of the motor and the stator of the motor.

3. A semi-hermetic twin-screw compressor according to claim 2, characterized in that: A stator cooling jacket is arranged on the outer side of the motor stator in the compressor housing, and a stator cooling channel is arranged on the stator cooling jacket.

4. A semi-hermetic twin-screw compressor according to claim 1, 2 or 3, characterized in that: A liquid collecting recess is arranged on the lower side of the compressor housing between the motor and the compressor body, and a liquid drain port is arranged on the side wall of the liquid collecting recess.

5. A semi-hermetic twin-screw compressor according to claim 4, characterized in that: The liquid collecting recess is arranged at the lower side of the motor cooling medium passage; a cooling medium air inlet chamber is formed in the compressor housing between the motor cooling air inlet and the motor.

6. A semi-hermetic twin-screw compressor according to claim 4, characterized in that: The compressor housing is located between the motor and the compressor body. The left and right sides of the upper part are provided with compressor air inlets. The compressor housing is located between the motor and the compressor body. The compressor air inlet and liquid return port is also provided.

7. A semi-hermetic twin-screw compressor according to claim 6, characterized in that: Both sides of the rear part of the compressor housing are provided with economizer air inlets which are connected with the compression chamber, and the lower side of the rear end part of the compressor housing is provided with an exhaust port.

8. The semi-hermetic twin-screw compressor according to claim 1, characterized in that: A bearing seat structure for supporting a shaft portion of a compressor rotor is provided in a section between the motor and the compressor body in the compressor housing.

9. A semi-hermetic twin-screw compressor system, comprising the semi-hermetic twin-screw compressor according to claim 7, characterized in that: The economizer air inlet is connected to the evaporator, the compressor air inlet is connected to the economizer, the motor cooling air inlet is connected to the condenser outlet or the liquid reservoir outlet, the drain port is connected to the compressor air inlet return port via a drain branch path, a liquid pump, and a post-pump drain branch path, a liquid discharge path is provided on the drain branch path and is connected to a drain valve, the exhaust port is connected to the liquid pump via a high-pressure gas path, and an exhaust path connected to a system oil separator is provided on the high-pressure gas path.

10. A semi-hermetic twin-screw compressor system, comprising the semi-hermetic twin-screw compressor according to claim 7, characterized in that: The economizer air inlet is connected to the evaporator, the compressor air inlet is connected to the economizer, the motor cooling air inlet is connected to the condenser outlet or the liquid storage outlet, the drain port is connected to the system oil separator via a drain branch path, a liquid pump, a post-pump drain branch path, and an exhaust path, the exhaust port is connected to the exhaust path, and a liquid discharge path is provided on the drain branch path and is connected to a drain valve.

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