Compressor and system comprising same

Abstract

The present application discloses a compressor, comprising: a shell, a driving motor, and a rotating shaft, as well as an impeller device and a rotor device. The rotating shaft can drive the impeller device and the rotor device to rotate synchronously, thereby making the driving motor, the impeller device, and the rotor device rotate synchronously all at the same rotational speed. In the compressor of the present application disclosure, the impeller device and the rotor device are within the shell; before entering the rotor device, a fluid / gas first passes through the impeller device for conducting first-stage compression to increase the pressure and density of the fluid / gas, and then it enters the rotor device for a second-stage compression to further decrease the volume and increase the pressure of the fluid / gas. Therefore, the compressor can have a larger compression ratio, larger suction capacity, and higher compressor efficiency compared to typical screw compressor with the same rotor device configuration.

Description

Technical Field

[0001] The present disclosure relates to the field of Heating, Ventilation, Air-Conditioners (and / or Heat-Pumps), and Refrigeration (HVACR) systems, in particular to the compressor used in such systems.Background Art

[0002] A conventional climate control (air-conditioner and / or heat-pump and / or refrigeration) system comprise of a compressor, a condenser, a throttling device, and an evaporator that are all connected by pipelines and filled with a refrigerant. The refrigerant circulates through the compressor, the condenser, the throttling device, and the evaporator, in such a way that it enables external air-conditioning or heating or refrigeration to occur. Starting with the compressor, the refrigerant is compressed into a high-temperature and high-pressure refrigerant gas, then it releases heat as it flows through the condenser and gets liquefied / condensed into a high-pressure refrigerant liquid, then it gets throttled in the throttling device into a low-pressure refrigerant, and next it absorbs heat as it flows through the evaporator and gets vaporized / evaporated into a low-pressure refrigerant gas, and finally the low-pressure refrigerant gas enters back the compressor to complete the cycle of the refrigerant through the air-conditioner / heat-pump / refrigeration system.

[0003] The compressor is considered the most important and vital component in such systems, impacting the energy consumption and the refrigerating capacity of the air-conditioners, heat-pumps, and refrigeration systems. In general; The more efficient the compressor, the lower the energy consumed by the system; The greater the suction capacity of the compressor, the greater the refrigerating / heating capacity of the system; And the higher the compression ratio of the compressor, the higher the temperature of the heating outlet water of the system.Summary of the Invention

[0004] In a first aspect, the present application provides a compressor, comprising: a shell, a driving motor, and a rotating shaft, as well as an impeller device and a rotor device. The shell comprises a compressor inlet and a compressor outlet. The driving motor and the rotating shaft are disposed within the shell, and the driving motor is connected to the rotating shaft, and is configured to drive the rotating shaft to rotate. The impeller device and the rotor device are within the shell, connected onto the rotating shaft, and located at two opposite sides of the driving motor, so that the rotating shaft can drive the impeller device and the rotor device to rotate synchronously, thereby making the driving motor, the impeller device and the rotor device rotate synchronously at the same rotational speed. Wherein, the motor, the impeller device, and the rotor device are configured to rotate along with the rotating shaft, and the gas entering the compressor through the compressor inlet first flows through the impeller device for conducting first-stage compression to increase the pressure of the gas, next it flows through the driving motor to cool the driving motor, then it flows through the rotor device for conducting second-stage compression to further increase the pressure of the gas, and it is finally discharged out of the compressor through the compressor outlet.

[0005] According to the first aspect above, at least one fluid channel is provided between the driving motor and the shell, and the fluid channel extends along an axial direction of the rotating shaft. Wherein, the gas after conducting the first-stage compression by the impeller device can flow through the driving motor along the at least one fluid channel, so as to cool the driving motor.

[0006] According to the first aspect above, the compressor further comprises a diffuser. The diffuser is disposed downstream of the impeller device and upstream of the driving motor,and the diffuser is configured to further increase the pressure of the gas after the completion of the first-stage compression.

[0007] According to the first aspect above, the diffuser is a vaneless diffuser or vaned diffuser or mixed vaneless / vaned diffuser.

[0008] According to the first aspect above, the impeller device comprises an impeller shroud and a impeller wheel. The impeller wheel is disposed within the impeller shroud, and the impeller wheel is configured to increase the gas flow kinetic energy and pressure through a displacement of the gas flow.

[0009] According to the first aspect above, the impeller wheel is a mixed-flow impeller wheel and configured to increase the gas flow kinetic energy and pressure through an axial and radial displacement of the gas flow.

[0010] According to the first aspect above, the diffuser is configured to guide the gas flowing through the impeller device to be discharged toward the driving motor along the axial direction of the rotating shaft.

[0011] According to the first aspect above, the diffuser comprises an annular flow passage. In the flow direction, the upstream part of the annular flow passage in the axial direction is aligned with an outlet end of the impeller device, and the cross-sectional area of the downstream part of the annular flow passage in the axial direction gradually increases in such a way so that the flow velocity of the gas discharged out of the annular flow passage can be reduced gradually..

[0012] According to the first aspect above, the rotor device comprises a male rotor and a female rotor that are engaged with each other. Wherein, the male rotor is connected onto the rotating shaft to be driven by the rotating shaft to rotate, and the female rotor is driven by the male rotor to rotate.

[0013] According to the first aspect above, the motor is a variable frequency motor, and the motor is configured to drive the rotating shaft to rotate at a rotational speed of 1,000-20,000 rpm.

[0014] According to the first aspect above, the driving motor is configured to drive the rotating shaft to rotate at a rotational speed of 2,000 -12,000 rpm.

[0015] According to the first aspect above, the driving motor is a fixed speed motor.

[0016] In a second aspect, the present application provides a system comprising the compressor according to the first aspect, and the system is an air-condition system and / or a heat-pump system and / or a refrigeration system and / or an industrial refrigeration system.

[0017] Other features, advantages and embodiments of the present application may be set forth or become apparent by consideration of the following detailed description, accompanying drawings and claims. In addition, it should be understood that the above summaries of the invention and the following specific embodiments are all exemplary and intended to provide further explanations rather than limit the scope of the present application to be claimed. However, the detailed description and specific examples indicate only preferred embodiments of the present application. Various changes and modifications within the spirit and scope of the present application will become apparent to those skilled in the art from this detailed description.Brief Description of the Drawings

[0018] FIG. 1A is a stereoscopic structure diagram of the turbo-screw compressor according to one embodiment of the present application; FIG. 1B is a left view of the turbo-screw compressor shown in FIG. 1A; FIG. 2A is a sectional view of the turbo-screw compressor shown in FIG. 1B along a line A-A; FIG. 2B is a sectional view of the turbo-screw compressor shown in FIG. 1B along a line B-B; FIG. 3A is a stereoscopic structure diagram of an impeller device in FIG. 2A at an angle; FIG. 3B is a stereoscopic structure diagram of an impeller device in FIG. 2A at another angle; FIG. 4A is a stereoscopic structure diagram of a diffuser in FIG. 2A at an angle; FIG. 4B is a stereoscopic structure diagram of a diffuser in FIG. 2A at another angle; and FIG. 5 is a stereoscopic structure diagram of a rotating shaft in FIG. 2A. Detailed Description of Embodiments

[0019] Various specific embodiments of the current new art in the present application will be described below with reference to the accompanying drawings, which constitute a part of the specification. It should be understood the terms used here to represent directions, such as "front", "rear", "upper", "lower", "left", "right", "top", and "bottom" are used in the present application to describe various example structural parts and elements of the present application, these terms used herein are determined based on example orientations shown in the accompanying drawings for ease of illustration only. Since the embodiments disclosed in the present application may be disposed in different directions, these terms that represent directions are for illustration only and should not be regarded as limiting.

[0020] FIGs. 1A and 1B show a structure of a compressor 100 according to one embodiment of the present application, for illustrating an external structure of the compressor 100. Wherein, FIG. 1A is a stereoscopic structure diagram of the compressor 100, and FIG. 1B is a left view of FIG. 1A. As shown in FIGs. 1A and 1B, the compressor 100 comprises a shell 101 and the shell 101 comprises a compressor inlet 102 and a compressor outlet 103. The shell 101 is approximately in the shape of a long cylinder, and the compressor inlet 102 and the compressor outlet 103 are respectively located at two ends of the shell 101. The refrigerant gas enters the compressor 100 through the compressor inlet 102, flows approximately along the shell length direction, and after being compressed, the gas is discharged out of the compressor 100 through the compressor outlet 103. In this embodiment, the compressor inlet 102 is located at the left end of the shell 101, and the compressor outlet 103 is located at a side of the right end of the shell 101.

[0021] FIGs. 2A and 2B show an internal structure of the compressor 100 shown in FIG. 1A. Wherein, FIG. 2A shows a sectional view of the compressor 100 along a line A-A, FIG. 2B shows a sectional view of the compressor 100 along line B-B, and the dotted line box shows a partially enlarged view. As shown in FIGs. 2A and 2B, the compressor 100 further comprises a rotating shaft 208, an impeller device 220, a driving motor 210, and a rotor device 211 which are all within the compressor shell 101. The rotating shaft 208 extends in a common length direction with the shell 101, and the rotating shaft 208 rotates about its axis x. The impeller device 220, the driving motor 210, and the rotor device 211 are all connected directly to the rotating shaft 208 and rotate synchronously with the rotation of the rotating shaft at the same rotational speed 208. In this embodiment, the impeller device 220 is connected to a left end of the rotating shaft 208, that is, an end close to the compressor inlet 102. The rotor device 211 is connected to a right side of the rotating shaft 208, that is, a side close to the compressor outlet 103. The driving motor 210 is connected between the impeller device 220 and the rotor device 211, that is, approximately at the middle of the rotating shaft 208. Thus, the refrigerant gas entering the compressor 100 from the compressor inlet 102 can flow through the impeller device 220, the driving motor 210, and the rotor device 211 in a serial sequence, before getting discharged out of the compressor 100 from the compressor outlet 103. In this embodiment, the driving motor 210 is used to drive the rotating shaft 208 to rotate, and the rotation of the rotating shaft 208 can drive the impeller device 220 and the rotor device 211 to rotate synchronously, thereby enabling the impeller device 220, the driving motor 210 and the rotor device 211 to rotate all synchronously at the same rotational speed.

[0022] The impeller device 220 comprises an impeller casing or shroud 221 and an impeller wheel or disc, and the impeller wheel and the impeller casing 221 jointly rotate around the axis x. In this embodiment, the impeller wheel and the impeller casing 221 are integrally casted or processed (shrouded impeller, with a rotating impeller casing). The impeller wheel includes a plurality of blades and / or splitters spanning in-between the impeller hub and the impeller shroud or casing. The impeller wheel is connected to the left end of the rotating shaft 208, so that the rotation of the rotating shaft 208 can drive the impeller wheel and the impeller casing 221 to rotate, thereby guiding the gas flowing from the compressor inlet 102 through the impeller wheel for a first-stage compression. In other embodiments, the impeller device can comprise a sperate impeller casing (un-shrouded impeller, with a stationary impeller casing). During the first-stage compression, the volume of the gas is compressed, so that the pressure of the gas increases, and the gas can be guided by the impeller wheel to move in a predetermined direction and be discharged to a subsequent component. In this embodiment, the impeller wheel includes a mixed-flow impeller wheel 222, and the mixed-flow impeller wheel 222 is fastened and connected to the left end of the rotating shaft 208 through bolts or some other means 225. The mixed-flow impeller wheel 222 increases the gas flow kinetic energy and pressure through a radial and axial displacement of the gas flow. In some specific embodiments, the gas enters from the compressor inlet 102 into the mixed-flow impeller wheel 222 in the axial direction, and then the mixed-flow impeller wheel 222 guides the gas to be discharged in an oblique direction that is inclined to the axial direction. Compared with a centrifugal / radial-flow impeller wheel and an axial-flow impeller wheel, the mixed-flow impeller wheel 222 can greatly increase the gas pressure while guiding the gas flow in a more compact space. In some other embodiments, the impeller wheel may also include the fully centrifugal / radial-flow impeller wheel or the axial-flow impeller wheel. A more specific structure of the impeller device 220 will be described in detail in conjunction with FIGs. 3A and 3B.

[0023] The compressor 100 further comprises a diffuser 241 within the shell 101. The diffuser 241 is immediately adjacent to the impeller device 220 downstream of the impeller device 220. Moreover, the diffuser 241 is upstream of the driving motor 210. That is to say, the gas within the compressor 100 first flows through the impeller device 220, then flows through the diffuser 241, and next it flows through the driving motor 210. The diffuser 241 can convert a part of the kinetic energy of the gas flowing out of the impeller device 220 into pressure energy, so as to further increase the pressure of the gas. In this embodiment, the diffuser 241 is configured so as to guide the gas discharged along an oblique direction from the impeller device 220 to be discharged toward the driving motor 210 in an axial direction. Moreover, in this embodiment, the diffuser 241 is a vaneless diffuser but in other embodiments, it can be a vaned diffuser or a combination of both. In the flow direction, the diffuser 241 comprises an annular flow passage 242 in which the upstream part (that is, the left side) of the annular flow passage 242 is aligned with the outlet end 326 of the impeller device 220 (shown in FIG. 3B), so that the gas discharged out of the impeller device 220 can enter the diffuser 241 directly. The cross-sectional area of the downstream part of the annular flow passage 242 gradually increases in a such way so that the flow velocity of the gas discharged out of the annular flow passage 242 can be reduced gradually, thus increasing the pressure of the gas discharged out of the annular flow passage 242 through the downstream part (that is, right side) into the motor while avoiding flow separation.

[0024] In this embodiment, the diffuser 241 is stationary / fixedly connected to the shell 101, so that the rotation of the rotating shaft 208 does not affect the diffuser 241, and the diffuser 241 does not rotate with the rotation of the rotating shaft 208. The compressor 100 further comprises a bearing 251, the bearing 251 is mounted between the rotating shaft 208 and the diffuser 241 to support the rotation of the rotating shaft 208 along the axis x through the diffuser 241. A more specific structure of the diffuser 241 will be described in detail in conjunction with FIGs. 4A and 4B.

[0025] The motor 210 comprises a motor rotor portion 256 and a motor stator portion 254 that are relatively rotatable. The motor stator portion 254 is fixedly connected to the shell 101, for example, fixed to the shell 101 by screws 255 or any other means. The motor rotor portion 256 is fixedly connected to the rotating shaft 208 so that the rotation of the motor rotor portion 256 can drive the rotating shaft 208 to rotate. In this embodiment, a groove 258 is provided on the rotating shaft 208, and a driving key 257 is mounted on the motor rotor portion 256, the groove 258 and the driving key 257 cooperate with each other, so that the motor rotor portion 256 is fixedly connected to the rotating shaft 208. After the motor 210 is energized, the motor stator portion 254 and the motor rotor portion 256 electromagnetically interact with each other, so that the motor rotor portion 256 rotates relative to the motor stator portion 254. At least one fluid channel 253 is provided between the motor stator portion 254 of the motor 210 and the inner wall of the shell 101, and at least one fluid channel 253 extends along the axial direction of the rotating shaft 208, and is in fluid communication with the gas outlet of the diffuser 241 and the rotor inlet of the rotor device 211so that the gas discharged out of the diffuser 241 along the axial direction can flow through the motor 210 to cool down the motor before it enters the rotor device 211 for a second-stage compression. Since the impeller device 220 belongs to velocity-type compression with a relatively low compression ratio, the temperature of the gas discharged out of the impeller device 220 and the diffuser 241 is relatively low, thereby enabling the gas discharged out of the impeller device 220 and the diffuser 241 to cool the motor stator portion 254 of the motor 210 while flowing through the motor 210. In this embodiment, there is at least one fluid channel 253 defined by a groove connected onto the inner wall of the shell 101, and the at least one fluid channel 253 comprises five fluid channels 253 (not specifically shown in the figure) uniformly arranged around the axis x. In other embodiments, the fluid channel 253 may also be in any other known manner, or be in other numbers, such as more or less. In some embodiments, the fluid channel 253 may be an annular fluid channel around the axis x. Moreover, in this embodiment, the motor 210 further comprises a plurality of through-holes 259 penetrating through the motor rotor portion 256 along the axial direction, wherein the through-holes 259 also connect the outlet of the diffuser 241 and the inlet of the rotor device 211, so that part of the gas discharged out of the diffuser 241 along the axial direction can flow the through-holes 259 thereby cooling the motor rotor portion 256 of the motor 210 before it enters the rotor device 211 for a second-stage compression. In some other embodiments, the through-hole 259 may not be comprised, but only the fluid channel 253 is comprised. A more specific structure of the motor 210 will be described in detail in conjunction with FIG. 5.

[0026] In this embodiment, the rotor device 211 comprises a pair of rotors arranged in parallel, and the pair of rotors comprises a male rotor 212 and a female rotor 213. The male rotor 212 is connected to the rotating shaft 208 so that the male rotor 212 can be driven by the rotating shaft 208 to rotate. The female rotor 213 and the male rotor 212 are engaged with each other so that the rotation of the male rotor 212 can drive the female rotor 213 to rotate together. In this embodiment, the male rotor 212 is integrally formed with the rotating shaft 208, so that the male rotor 212 and the rotating shaft 208 rotate together. More specifically, the male rotor 212 and the female rotor 213 are respectively provided with a plurality of helical teeth, and the pair of rotors form an engaged structure through their respective teeth. The rotor assembly 211 is provided with the rotor inlet 216 and a rotor outlet 217, and the rotor inlet 216 is located at the left end of the rotor device 211 and is in fluid communication with the fluid channel 253. The rotor outlet 217 is located at the right end of the rotor device 211 and is in fluid communication with a compressor outlet 103. Moreover, a plurality of compression cavities 218 that are spaced apart are jointly formed between the pair of rotors and the shell 101. With the rotation of the pair of rotors, each compression cavity 218 moves right from the rotor inlet 216 to the rotor outlet 217 along the axial direction of the rotating shaft 208, and at the same time, the volume of the compression cavity 218 also gradually decreases, so that gas in the compression cavity 218 is gradually compressed, thereby enabling the gas flowing through the rotor device 211 to complete the second-stage compression.

[0027] Thus, the gas entering the compressor 100 from the compressor inlet 102 can flow through the motor 210 to cool the motor 210 after being subjected to the first-stage compression by the impeller device 220, then pass through the rotor device 211 to complete the second-stage compression of the gas, and finally be discharged out of the compressor 100 from the compressor outlet 103. After the gas passes through the impeller device 220 from the compressor inlet 102 to increase pressure, the density of the gas entering the rotor device 211 is increased compared to a compressor that does not comprise the impeller device 220 and only uses the rotor device 211 to compress the gas. Therefore, in a case that the compressor 100 reaches the same discharge volume flow rate and discharge pressure, the gas after being subjected to the two stages of compression by the impeller device 220 and the rotor device 211 can have a larger suction volume flow rate and compression ratio. Therefore, the heat-pump systems using the compressor 100 of the present application can have a greater refrigerating / heating capacity and a higher heating outlet water temperature. And the air-conditioner / refrigeration systems using the compressor 100 of the present application can have a greater refrigerating capacity.

[0028] In some embodiments, the compressor 100 may further comprise a slide valve (not shown in the figure), which is placed around the rotor device 211 to further control and adjust the compression ratio of the compressor 100. Moreover, in some embodiments, the rotor device may comprise only one screw rotor.

[0029] In this embodiment, the motor 210 is a variable frequency motor. The variable frequency motor may make the rotating shaft 208 have a wider rotational speed range, thereby meeting the rotational speed requirements of the impeller device 220 and the rotor device 211. In this embodiment, the motor 210 is configured to drive the rotating shaft 208 to rotate at a rotational speed of 1,000-20,000 rpm. That is to say, the rotational speeds of the impeller device 220 and the rotor device 211 are both 1,000-20,000 rpm. In some embodiments, the drive motor 210 is configured to drive the rotary shaft 208 to rotate at a speed of 2000-12,000 rpm. And in some embodiments, the driving motor can also be a fixed speed motor and can be used with other additional parts such as a rotor slide valve unloading mechanism or a pre-rotating vane.

[0030] The impeller device 220 performs gas compression in a manner of velocity-type compression and therefore requires a higher rotational speed of the impeller device 220. Generally speaking, in the case of reaching the same compression ratio, the lower the rotational speed of the impeller device 220, the larger the size of the impeller wheel. Therefore, in some embodiments, to keep the size of the impeller wheel within the range of the shell 101, the rotational speed of the impeller device 220 is set to be above 1,000 rpm. In some other embodiments, the rotational speed of the impeller device 220 is set to be above 2,000 rpm.

[0031] The rotor device 211 performs gas compression in a manner of volumetric compression, compresses the gas in the compression cavity through the volume change of the compression cavity formed by the engagement of the male rotor and the female rotor, and does not require a high rotational speed of the rotor device 211. Limited by the maximum operating rotational speed of a rolling bearing of the screw compressor, the rotational speed of the rotor device 211 cannot be too high, and if the rotational speed is too high, the wear from the rotor engaging will be accelerated, which will affect the reliability of the rotor device 211. In some embodiments, the rotational speed of the rotor device 211 is set to be within 20,000 rpm. In some other embodiments, the rotational speed of the rotor device 211 is set to be within 12,000 rpm.

[0032] Therefore, setting the rotating shaft 208 at a rotational speed within 1,000-20,000 rpm can meet the needs of the impeller device 220 and the rotor device 211, so that the impeller device 220 and the rotor device 211 are connected to the same rotating shaft 208 for operating coaxially and synchronously at the same rotational speed.

[0033] In the generally used heat pump system at present, the compression ratio of the system is generally within the range of 2-15 times. The compression ratio of the second-stage compression of the rotor device 211 usually needs to be less than 8, so as to ensure a smooth operation of the system and avoid an under-compression state. Moreover, in a unit comprising the same compressor, a refrigerating working condition with a low compression ratio is generally operated in summer, and a heating working condition with a high compression ratio is generally operated in winter. The applicant has found that when the compression ratio of the first-stage compression of the impeller device 220 is between 1.2-1.8, the requirement of dual-working-condition operation of refrigerating and heating of the heat pump system can be well considered. Therefore, a mixed-flow impeller wheel 222 with a medium-low compression ratio is particularly suitable for the impeller device 220 of the present application. Those skilled in the art can understand that, for a heat pump system that requires a particularly high compression ratio, the impeller device 220 may further comprise a centrifugal impeller wheel.

[0034] FIGs. 3A and 3B show a specific structure of the impeller device 220, wherein FIG. 3A is a stereoscopic structure diagram of the impeller device 220 viewed from left to right and FIG. 3B is a stereoscopic structure diagram of the impeller device 220 viewed from right to left. As shown in FIGs. 3A and 3B, the mixed-flow impeller wheel 222 comprises a plurality of blades361 and an inner hub 327, and the inner hub 327 is inside the impeller casing or shroud 221 and is spaced apart from the impeller shroud 221 by a certain distance. The blades 361 are spanning in-between the impeller shroud 221 and the impeller hub 327. An annular outlet end 326 is formed on the right side between the impeller shroud 221 and the impeller hub 327, and the gas is discharged out of the impeller device 220 from the outlet end 326.

[0035] The impeller device 220 further comprises a circular outer ring 323 and a circular inner ring 324, and the compressor inlet 102 is defined between the outer ring 323 and the inner ring 324. Specifically, the left side of the impeller casing 221 has a round opening 328, and the outer ring 323 is formed by an edge of the circular opening 328 protruding outward along the axial direction. The impeller device 220 further comprises a support seat 329, and the support seat 329 is located at the left side of the center of the impeller shroud 327 so that the bolt 225 can pass through the support seat 329 to connect the mixed-flow impeller wheel 222 to the rotating shaft 208. The inner ring 324 is formed by an edge of the support seat 329 protruding outward along the axial direction. Thus, the compressor inlet 102 can be formed in the round opening 328 between the outer ring 323 and the inner ring 324. The gas enters the left side of the mixed-flow impeller wheel 222 from the compressor inlet 102 and is compressed by the rotating blades 361 before being discharged out of the outlet end 326 of the impeller device on the right side.

[0036] FIGs. 4A and 4B show a specific structure of a diffuser 241, wherein FIG. 4A is a stereoscopic structure diagram of the diffuser 241 viewed from left to right and FIG. 4B is a stereoscopic structure diagram of the diffuser 241 viewed from right to left. As shown in FIGs. 4A and 4B and in conjunction with FIG. 2A, the diffuser 241 comprises an outer wall 443 and an inner wall 445, the outer wall 443 being outside of the inner wall 445 around the inner wall 445, and spaced apart from the inner wall 445 by a certain distance to form the annular flow passage 242. In this embodiment, in the axial direction from left to right, the inner surface of the outer wall 443 first extends along the axial direction, and then gradually expands outward. Moreover, the outer surface of the inner wall 445 first extends along the axial direction, and then gradually expands inward. Thus, the annular flow passage 242 between the inner surface of the outer wall 443 and the outer surface of the inner wall 445 approximately extends along the axial direction in the axial direction from left to right, and then gradually expands outward to form a streamlined shape (such as a bell-mouth shape) with a gradually changing cross-sectional area.

[0037] The diffuser 241 further comprises a center sleeve 448, and the center sleeve 448 is connected to the center of the inner wall 445. The center sleeve 448 extends along the axial direction, and the center sleeve 448 has a hollow shape, the inside of which is used to accommodate the bearings 251 so that the diffuser 241 can be mounted to the rotating shaft 208.

[0038] The diffuser 241 further comprises at least one supporting rib 446, and the supporting ribs 446 extend along the radial direction and are connected between the inner wall 445 and the outer wall 443, so as to connect the inner wall 445 with the outer wall 443 on the premise that the annular flow passage 242 is not affected. In this embodiment, the at least one supporting rib 446 includes three supporting ribs 446 which are evenly arranged along the circumferential direction. In other embodiments, the supporting ribs 446 may also be set in other numbers.

[0039] The diffuser 241 further comprises at least one reinforcing rib 447, and the reinforcing rib 447 extends along the radial direction, and is connected between the left side of the inner wall 445 and the center sleeve 448. The reinforcing ribs 447 can reinforce the strength of the inner wall 445 used to form the annular flow passage 242, so as to prevent the gas having a higher pressure after the first-stage compression from extruding the inner wall 445 inward along the radial direction while flowing through the annular flow passage 242. In this embodiment, the at least one reinforcing rib 447 includes three reinforcing ribs 447, which are evenly arranged along the circumferential direction. In other embodiments, the reinforcing ribs 447 may also be set in other numbers. In this embodiment, the diffuser is a vaneless diffuser. In other embodiments, the diffuser cane be a vaned diffuser or a combination of both types.

[0040] FIG. 5 shows a stereoscopic structure diagram of the motor 210, the rotating shaft 208 and the male rotor 212. As shown in FIG. 5, a threaded hole 552 is provided on the left end face of the rotating shaft 208, and the threaded hole 552 is used to cooperate with the bolt 225, so as to fasten and connect the impeller device 220 to the left end of the rotating shaft 208. The rotating shaft 208 further comprises a step portion 562 and a step portion 563 sequentially in the axial direction from left to right, and each step portion is formed by protruding along the radial direction from the outer surface of the rotating shaft 208. The step portion 562 is used to limit the position of the impeller device 220, for example, the center portion of the inner cover 327 of the impeller device 220 can cling onto the radial surface of the step portion 562. The step portion 563 is used to limit the position of the diffuser 241, for example, the center portion of the bearing 251 of the diffuser 241 can cling onto the radial surface of the step portion 563. Thus, the impeller device 220 and the diffuser 241 can be connected to the leftmost end of the rotating shaft 208.

[0041] The male rotor 212 in the rotor device 211 is on the side of the rotating shaft 208 opposite to the impeller device 220, that is, on the right side of the rotating shaft 208.

[0042] The driving motor 210 is connected to the right side of the impeller device 220 and the diffuser 241 and is connected to the left side of the male rotor 212. Moreover, the first-stage compressed gas discharged out of the impeller device 220 and the diffuser 241 can enter the rotor device 211 through the fluid channel 253 outside the motor stator portion 254, or enter the rotor device 211 through the through-holes 259 within the motor rotor portion 256. Moreover, the motor 210 is connected to the rotating shaft 208 through the driving key 257 on the motor rotor portion 256 and the groove 258 in the rotating shaft 208. When the motor stator portion 254 is fixed relative to the shell 101, the rotation of the motor rotor portion 256 relative to the motor stator portion 254 can drive the rotating shaft 208 to rotate relative to the shell 101.

[0043] Thus, the impeller device 220, the motor 210, and the rotor device 211 can be in fluid communication and rotate synchronously with the rotating shaft 208.

[0044] In some embodiments, the impeller device can be a mixed-flow or a centrifugal / radial-flow or an axial flow impeller type, comprises a single stage or more than one stage, comprises a shrouded or a partially shrouded or an un-shrouded impeller configuration, comprises full blades or full blades and splitter / partial blades or any other blade configuration.

[0045] In some embodiments, the impeller device can be a centrifugal / radial-flow type impeller, or a mixed-flow type impeller, or an axial-flow type impeller in which it comprises an impeller wheel including a plurality of blades spanning in-between the impeller hub and the impeller shroud or casing and configured to increase the gas flow kinetic energy and pressure through a displacement of the gas flow. The impeller device can be a shrouded impeller (with a rotating impeller casing) or an un-shrouded impeller (with a stationary impeller casing). The impeller device can be without splitters (full blades) or with splitters (partial blades). The impeller device outlet can be fully radial (centrifugal / radial-flow impeller) or at an oblique angle (mixed-flow impeller) or fully axial (axial-flow impeller). The impeller device can be manufactured by means of casting or machining or additive manufacturing or any of the other manufacturing means. The impeller surface finish can be polished or un-polished or grinded or un-grinded or any of the other surface finish means. Each of the blades includes a leading edge and a trailing edge opposite to the leading edge. A pressure side surface extends between the leading edge and the trailing edge. A suction side surface is opposite to the pressure side surface and extends between the leading edge and the trailing edge. The impeller blade surfaces can have any, some, or all the following features or characteristics: sweep, tilt, lean, bow, ripples, grooves, S-shaped, or any other alternative features to improve the efficiency and performance of the impeller device.

[0046] In some embodiments, the diffuser can be a vaneless diffuser or a vaned diffuser or a combination of vaneless and vaned diffuser or any other diffuser configuration. The diffuser is configured in such a way to increase the static pressure of the refrigerant gas by reducing its velocity while guiding the gas flow towards the driving motor along the axial direction of the rotating shaft. The diffuser comprises of an annular flow passage. The upstream part of the annular flow passage is aligned with the outlet of the impeller device while the downstream part of the annular flow passage is aligned with the driving motor. The diffuser cross-sectional area between the upstream part and downstream part gradually changes in a way to reduce the flow velocity and to increase the flow pressure while avoiding flow separation.

[0047] In some embodiments, the motor can be a variable frequency (speed) motor type or a fixed frequency (speed) motor type, or any other motor configuration.

[0048] In some embodiments, the rotor device can be a screw rotor with single rotor or double rotors or any other rotor configuration or a combination of rotor configurations; In some embodiments, a slide valve or any other mechanical device configuration can be placed around the rotor device to further control and adjust the compression ratio of the compressor.

[0049] Existing screw compressors generally comprise only a motor and a rotor device, and the motor and the rotor device are connected to a common rotating shaft for synchronous rotation. The screw compressor is a volumetric compressor, wherein after the screw compressor sucks a gas, the gas passes through the rotor device to compress the gas volume for increasing the gas pressure. In some screw compressors, although the internal volume ratio of the screw compressor may be adjusted by disposing a slide valve, the maximum internal volume ratio of the screw compressor is 5.0 due to the limitation of structural design. For some heat pump systems that need a higher compression ratio, the single-stage screw compressor generally cannot reach the compression ratio required by the system, so that the screw compressor is in a state of under-compression for a long time, thereby resulting in large vibration and high gas discharge temperature of the screw compressor. However, if two or more stages of compressors are placed in a pipeline of the heat pump system, the system structure will be complicated and the cost will be high.

[0050] Moreover, for an air-conditioner / heat pump system using certain novel environmentally friendly refrigerants (for example R1234ze), under the working condition that an air conditioner operates at the same water temperature, because these refrigerants usually have a lower refrigerating capacity per unit volume, it is difficult to meet the refrigerating capacity of the heat pump system. Therefore, these environmentally friendly refrigerants cannot be directly used in existing heat pump system units. Usually, it is also necessary to increase the volume and displacement of the heat pump system units to meet the refrigerating capacity requirements, resulting in increased transformation costs.

[0051] In the compressor of the present application, the impeller device and the rotor device are both integrated into the shell; before entering the rotor device, the refrigerant gas first passes through the impeller device for conducting first-stage compression to increase pressure and density of the gas, and then it enters the rotor device for conducting second-stage compression to further decrease volume and increase the pressure of the gas. Therefore, the compressor can have a larger compression ratio, suction capacity and compressor efficiency compared to a screw compressor with the same rotor device configuration.

[0052] The compressor of the present application comprises the motor between the impeller device and the rotor device, and utilizes the gas discharged out of the impeller device to cool the motor, thereby solving the problem of heat dissipation of the motor. It is especially suitable for solving the problem of excessive heat generation of a variable frequency motor when the variable frequency motor is used to drive the rotating shaft.

[0053] The rotational speed of the rotating shaft of the compressor of the present application is set within a suitable range, so that the impeller device, the motor, and the rotor device can rotate synchronously without additionally using a variable gear, and the structure is simple. Moreover, the impeller device is smaller in size and may be accommodated inside the shell together with the motor and the rotor device. Also, by designing the impeller device with a suitable size, the discharge capacity of the impeller device is matched with the suction capacity of the rotor device, achieving a higher compressor efficiency.

[0054] The impeller device of the present application comprises a mixed-flow impeller wheel, which can have a greater compression efficiency compared with an axial-flow impeller wheel. And compared with a centrifugal-flow impeller wheel, the mixed-flow impeller wheel can have a lower pressure loss after the discharge out of the impeller device. Moreover, the compressor of the present application further comprises an axial diffuser which, besides increasing the gas pressure, can also guide the gas to flow along the axial direction of the rotating shaft, and cooperate with the mixed-flow impeller wheel to further reduce the pressure loss of the gas.

[0055] Moreover, an impeller device only needs to be disposed at an end, close to the gas suction side, of the compressor of the present application on the basis of the structure of the existing screw compressor, and the modification is small, so that the transformation cost is reduced.

[0056] In addition, since the compressor of the present application has an increased suction capacity compared with conventional screw compressors, the air-conditioner / heat-pump system comprising the compressor of the present application may reach a greater refrigerating capacity when using conventional refrigerants (for example R134a), and has a better environmental protection effect when using a refrigerant with a lower refrigerating capacity per unit (such as R1234ze).

[0057] Although the present disclosure has been described in conjunction with the examples of embodiments outlined above, various alternatives, modifications, variations, improvements and / or substantial equivalents, whether known or foreseeable now or soon, may become apparent to those of ordinary skill in the art. Accordingly, the examples of embodiments of the present disclosure set forth above are intended to be illustrative rather than restrictive / limiting. Various changes may be made without departing from the spirit or scope of the present disclosure. Accordingly, the present disclosure is intended to embrace all known or earlier developed alternatives, modifications, variations, improvements and / or substantial equivalents. The technical effects and technical problems in the specification are exemplary rather than restrictive / limiting. It should also be noted that the embodiments described in the specification may have other technical effects and may solve other technical problems.

Claims

1. A compressor, characterized in that the compressor comprises: a shell, the shell comprising a compressor inlet and a compressor outlet; a driving motor and a rotating shaft, the driving motor and the rotating shaft being within the shell, and the driving motor being connected to the rotating shaft and configured to drive the rotating shaft to rotate; and an impeller device and a rotor device, the impeller device and the rotor device being within the shell, connected onto the rotating shaft, and located at two opposite sides of the driving motor, so that the rotating shaft can drive the impeller device and the rotor device to rotate synchronously, thereby making the driving motor, the impeller device and the rotor device rotate synchronously at the same rotational speed; wherein the driving motor, the impeller device and the rotor device are configured to rotate along with the rotating shaft, and the gas entering the compressor through the compressor inlet first flows through the impeller device for conducting first-stage compression to increase the pressure of the gas, next it flows through the driving motor to cool the driving motor, then it flows through the rotor device for conducting second-stage compression to further increase the pressure of the gas, and it is finally discharged out of the compressor through the compressor outlet.

2. The compressor according to Claim 1, characterized in that: at least one fluid channel is provided between the driving motor and the shell, and the fluid channel extends along an axial direction of the rotating shaft; wherein the gas after conducting the first-stage compression by the impeller device can flow through the driving motor along the at least one fluid channel, so as to cool the driving motor.

3. The compressor according to Claim 2, characterized in that the compressor further comprises: a diffuser, the diffuser being disposed downstream of the impeller device and upstream of the driving motor, and the diffuser being configured to further increase the pressure of the gas after completion of the first-stage compression.

4. The compressor according to Claim 3, characterized in that: the diffuser can be a vaneless diffuser or vaned diffuser or mixed vaneless / vaned diffuser.

5. The compressor according to Claim 3, characterized in that: the impeller device comprises an impeller shroud and an impeller wheel, the impeller wheel being disposed within the impeller shroud, and the impeller wheel being configured to increase the gas flow kinetic energy and pressure through a displacement of the gas flow.

6. The compressor according to Claim 5, characterized in that: the impeller wheel is a mixed-flow impeller wheel and configured to increase the gas flow kinetic energy and pressure through an axial and radial displacement of the gas flow.

7. The compressor according to Claim 6, characterized in that: the diffuser is configured to guide gas flowing through the impeller device to be discharged toward the driving motor along the axial direction of the rotating shaft.

8. The compressor according to Claim 7, characterized in that: the diffuser comprises an annular flow passage, wherein in the flow direction, the upstream part of the annular flow passage in the axial direction is aligned with an outlet end of the impeller device, and the cross-sectional area of the downstream part of the annular flow passage in the axial direction gradually increases in such a way so that the flow velocity of the gas discharged out of the annular flow passage can be reduced gradually.

9. The compressor according to Claim 1, characterized in that: the rotor device comprises a male rotor and a female rotor that are engaged with each other, wherein the male rotor is connected onto the rotating shaft to be driven by the rotating shaft to rotate, and the female rotor is driven by the male rotor to rotate.

10. The compressor according to Claim 1, characterized in that: the motor is a variable frequency motor, and the motor is configured to drive the rotating shaft to rotate at a rotational speed of 1,000 - 20,000 rpm.

11. The compressor according to Claim 10, characterized in that: the driving motor is configured to drive the rotating shaft to rotate at a rotational speed of 2,000 -12,000 rpm.

12. The compressor according to Claim 1, characterized in that: the driving motor is a fixed speed motor.

13. A system comprising the compressor according to any of Claims 1 - 12, the system being an air-condition system and / or a heat-pump system and / or a refrigeration system and / or an industrial refrigeration system.

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