A micro high-speed centrifugal refrigerant compressor system

Abstract

The application discloses a kind of miniature high-speed centrifugal refrigerant compressor systems, including centrifugal compressor body, motor assembly, bearing system, cooling system and sealing structure.Centrifugal compressor body adopts centrifugal compression principle, and the shell adopts non-closed open type machining flow passage design, the inner wall of the shell and the bearing cover end face form vaneless parallel diffuser surface, impeller adopts three-dimensional twisted blade structure, radial bearing adopts semi-floating type floating ring bearing structure, through ball limit floating ring free rotation, form extrusion damping oil film, to improve high-speed running stability;High-voltage lead is led out through glass sintering connector, and the pressure resistance is not less than 4MPa.Cooling system adopts motor cooling and compressor cooling integrated design, and the inner wall of motor shell is provided with spiral groove and forms spiral cooling channel.The application has the advantages of small size, light weight, high integration, high efficiency and good reliability, and is suitable for heat pump compressor field in new energy commercial vehicle thermal management system.

Description

Technical Field

[0001] This invention relates to the field of refrigeration compressor technology, and specifically to a miniature high-speed centrifugal refrigerant compressor system. Background Technology

[0002] With the accelerated electrification of new energy vehicles, especially heavy-duty commercial vehicles, the performance requirements for thermal management systems are becoming increasingly stringent. The China VII emission standard has included heavy-duty commercial vehicles in the scope of greenhouse gas control. The energy efficiency of the vehicle's thermal management system directly affects overall energy consumption and carbon emissions. The high energy consumption of traditional PTC heating solutions is becoming increasingly prominent, making heat pump systems, with their COP of 2-4, an inevitable choice. As the core component of a heat pump system, the compressor's efficiency, reliability, and system integration directly determine the feasibility of the overall thermal management solution.

[0003] Currently, the compressors used in commercial vehicle heat pump systems are mainly divided into two types: scroll compressors and air-float centrifugal compressors, both of which have obvious defects.

[0004] Due to its working principle, the cooling capacity of a single scroll compressor is usually limited to 20kW. In the high cooling demand scenarios of heavy commercial vehicles with large-capacity battery packs (600kWh level), multiple compressors are often required to be connected in parallel, resulting in a large system size and high integration complexity, which makes it difficult to meet the requirements of the compact installation space of heavy trucks.

[0005] While air-bearing centrifugal compressors have emerged in the market, this type of solution has two inherent drawbacks: Firstly, air-bearing rotors, supported by an air film, have extremely low damping. Under actual operating conditions such as long-distance heavy loads, high vibrations, and harsh road conditions in commercial vehicles, their resistance to vibration and shock is insufficient, making it difficult to meet the stringent long-term reliability requirements of commercial vehicles. Secondly, air-bearing compressors require a large bearing clearance to maintain the air film, resulting in the wheel-housing clearance between the pressure roller and the pressure housing needing to be controlled at over 0.3mm. This leads to significant internal leakage in the compressor, low isentropic compression efficiency, and difficulty in breaking through the bottleneck in the overall coefficient of performance (COP). Especially in applications with cooling capacities below 50kW, it is difficult to improve the isentropic efficiency of centrifugal compressors supported by air-bearing compressors.

[0006] It is worth noting that although semi-floating bearings have been used in the turbocharger field (such as in products from Garrett and BorgWarner), the application scenarios of turbochargers are fundamentally different from those of this invention: First, turbocharger bearings operate in an atmospheric pressure environment, use mineral lubricating oil, and the bearing cavity is open to the outside atmosphere, resulting in lower requirements for oil circuit sealing; second, turbochargers use mineral oil; and third, turbocharger bearing housings operate in a normal atmospheric pressure environment.

[0007] Under SVPWM high-frequency drive conditions, existing high-speed compressor motors with ordinary enameled wire windings face a severe risk of inter-turn corona corrosion. This problem is particularly prominent when the operating frequency exceeds 1000Hz and the voltage is higher than 800V, seriously limiting the insulation life of the motor. Simultaneously, existing motor windings typically employ an impregnation process, resulting in limited heat dissipation. Furthermore, the cooling channels for the motor housing generally rely on casting, leading to complex and costly manufacturing processes. These issues collectively hinder further improvements in the reliability and economy of miniature high-speed centrifugal compressors. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a miniature high-speed centrifugal refrigerant compressor system, comprising a centrifugal compressor body, a motor assembly, a bearing system, and a cooling system. The centrifugal compressor body includes a pressure shell and a pressure roller, with a refrigerant compression gas flow channel formed within the pressure shell. The pressure roller is disposed inside the pressure shell for centrifugal compression of the refrigerant, and the axial clearance between the pressure roller and the pressure shell is 0.07mm to 0.15mm. The motor assembly includes a motor housing and a motor armature that is interference-fitted with the motor housing, used to drive the pressure roller to rotate. The bearing system includes a first radial bearing, a second radial bearing, and a thrust bearing. The first and second radial bearings are connected to a rotor shaft, which adopts a segmented assembly structure. The thrust bearing is disposed at the end of the rotor shaft to bear axial thrust loads. The cooling system includes a spiral cooling groove disposed on the inner wall of the motor housing, with an inlet and an outlet at each end of the spiral cooling groove. After the motor armature is installed, the outer surface of the motor armature and the spiral cooling groove together form a spiral cooling gas channel.

[0009] Preferably, it also includes a bearing cover, one end of which presses against the thrust bearing, the outer surface of the bearing cover and the inner bottom surface of the pressure shell cooperate to form a disc-shaped expansion cavity, and the other side of the bearing cover presses against the thrust bearing to limit the axial movement of the thrust bearing.

[0010] Preferably, the inner wall of the pressure shell forms a bladeless diffuser surface with parallel spacing between the end faces of the motor housing and the bearing cover, which is used to convert the kinetic energy of the compressed gas into pressure potential energy.

[0011] Preferably, it further includes a shaft seal, one side of which abuts against the back of the pressure roller, and the other side abuts against the thrust plate; the shaft seal has a piston ring groove on the side near the pressure roller, and a piston ring is assembled in the piston ring groove; The elastic tension of the piston rings ensures that they maintain initial radial sealing contact with the outer surface of the rotor shaft; the thrust plate and the shaft seal are limited by a fixed distance L1, and the distance L1 is 0.06 to 0.10 mm more than the height of the thrust bearing, so that the axial movement of the rotor shaft is controlled within the range of 0.06 to 0.10 mm.

[0012] Preferably, it also includes a thrust plate, which is fitted to the other side of the shaft seal and cooperates with the thrust bearing.

[0013] Preferably, the thrust bearing has two openings, which are asymmetrically arranged. A thrust bearing positioning pin is installed in each opening to radially limit the thrust bearing. The thrust bearing has multiple wedge-shaped surfaces.

[0014] Preferably, the motor housing integrates a front-end bearing support, which is used to install the first radial bearing. The rear end of the motor housing is fixedly connected to a rear end bearing support, which is used to install a second radial bearing. An oil reservoir is provided in the middle of the outer sides of the first and second radial bearings, and oil holes are evenly distributed in the oil reservoir to deliver lubricating oil to the inner diameter of the bearing.

[0015] Preferably, the outer circular surface of the first radial bearing is provided with a semi-circular groove, and the inner hole of the bearing support connected to the first radial bearing is provided with a corresponding other semi-circular groove. The two semi-circular grooves are joined together to form a cylindrical hole, and a ball bearing with the same diameter as the inner hole of the cylindrical hole is embedded in the cylindrical hole. One side of the ball abuts against the stepped surface of the bearing and bearing support, and a retaining spring is provided on the other side to limit the movement of the ball. The ball is used to constrain the free rotation of the first radial bearing.

[0016] Preferably, the rotor shaft includes a rotor shaft pressure wheel end, a permanent magnet, a magnet sleeve, and a rotor shaft support end; The magnet sheath radially clamps the rotor shaft pressure wheel end, the permanent magnet, and the rotor shaft support end together as an integral rotor assembly through an interference fit.

[0017] Preferably, it also includes a sealing structure, including a glass sintered connector, wherein the outer end of the glass sintered connector is provided with a connector, an adapter block cover and an electrical adapter block, and the outer end of the glass sintered connector is sealed for sealing the high-voltage lead wire.

[0018] The technical effects and advantages of this invention are as follows: 1. The bearing system of the present invention operates in a sealed high-pressure refrigerant cavity. In the cooling system, the spiral groove on the inner wall of the motor housing and the outer surface of the stator core together form a spiral cooling channel. The cooling system adopts an integrated design of motor cooling and compressor cooling. The present invention has the advantages of small size, light weight, high integration, high efficiency and good reliability, and is suitable for heat pump compressor scenarios in the thermal management system of new energy commercial vehicles.

[0019] 2. The cooling system in this invention includes a spiral cooling groove disposed on the inner wall of the motor housing. Spiral cooling groove has spiral groove inlet and outlet ports at both ends, including designed inlet and outlet ports. After the motor armature is installed, the outer surface of the motor armature and the spiral cooling groove together form a spiral cooling air channel.

[0020] 3. The radial bearing of this invention adopts a semi-floating floating ring structure: the semi-floating design constrains the rotation of the floating ring through ball bearings, forming a dynamic pressure supporting oil film on the inner side and a compression damping oil film on the outer side. The ball bearing limiting mechanism prevents the floating ring from rotating freely, transforming the fully floating rotating dynamic pressure film into a pure compression damping film, effectively suppressing oil film eddy and oscillation, significantly enhancing its resistance to vehicle impact, fundamentally eliminating the eddy excitation source of the outer oil film, and suppressing the occurrence of oil film eddy and oscillation.

[0021] 4. In this invention, the thrust plate and the shaft seal are fixed at a distance L1. The distance L1 is 0.06 to 0.10 mm more than the height of the thrust bearing 7, so that the axial movement of the rotor shaft is controlled within the range of 0.06 to 0.10 mm. An extrusion damping outer oil film is formed between its outer circular surface and the inner surface of the bearing support hole, which is used to absorb the vibration of the rotor when it runs at high speed, improve the impact resistance under vehicle impact conditions, and support the rotor to run stably at high speed above 120,000 rpm.

[0022] 5. The front-end bearing support or rear-end bearing support of the present invention can be made of aluminum alloy material, without being limited to materials such as cast iron with low thermal expansion coefficient; aluminum alloy bearing support has the advantages of low density, low machining cost and good thermal conductivity, and can further reduce manufacturing cost and reduce the weight of the whole machine while meeting the extrusion damping function. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of the overall structure of the miniature high-speed centrifugal refrigerant compressor system of the present invention; Figure 2 This is a schematic diagram of the pressure shell and diffuser channel structure of the present invention; Figure 3 This is a schematic diagram of the radial bearing and semi-floating constraint structure of the present invention; Figure 4 This is a schematic diagram of the spiral cooling groove structure of the motor housing of the present invention; Figure 5 This is a schematic diagram of the thrust bearing and axial positioning structure of the present invention; Figure 6 Schematic diagram of the thrust bearing oil passage and oil hole of the present invention; Figure 7 This is a schematic diagram of the glass sintering connector installation of the present invention; Figure 8 This is a cross-sectional view of the overall structure of the present invention, in which the bearing support is located at the pressure end of the bearing.

[0024] In the diagram: 1. Pressure shell; 2. Locking nut; 3. Pressure roller; 4. Shaft seal; 5. Thrust plate; 6. Bearing cover; 7. Thrust bearing; 8. Motor housing; 9. Motor armature; 10. Rotor shaft; 101. Rotor shaft pressure roller end; 102. Permanent magnet; 103. Magnet sleeve; 104. Rotor shaft support end; 11. Rear end bearing support; 121. First radial bearing; 122. Second radial bearing; 13. Snap ring; 14. Ball bearing; 15. Connector; 16. Adapter block cover; 17. Electrical adapter block; 18. Glass sintered connector; 19. Piston ring; 20. Thrust bearing locating pin; 21. Oil hole; 801. Spiral groove inlet and outlet; 802. Spiral cooling groove; 803. Front end bearing support. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0026] Please see Figure 1-8 As shown, this embodiment provides a micro high-speed centrifugal refrigerant compressor system, including a centrifugal compressor body, a motor assembly, a bearing system, a cooling system, and a sealing structure; the centrifugal compressor body includes a pressure shell 1 and a pressure roller 3. The pressure shell 1 adopts a non-closed open machined flow channel design, and the inner wall of the flow channel is machined, with a surface roughness lower than that of the cast shell, thereby improving the isentropic compression efficiency. The inner wall of the pressure shell 1 and the end face of the bearing cover 6 form a bladeless parallel diffuser surface. The pressure roller 3 adopts a three-dimensional twisted blade structure; the motor assembly adopts a sensorless permanent magnet synchronous motor.

[0027] This refrigerant compressor system boasts a pressure ratio of up to 4.0 and a cooling capacity exceeding 25kW. The motor assembly utilizes a sensorless permanent magnet synchronous motor driven by SVPWM, operating at a voltage range of 450–850VDC, with a rated speed of up to 120,000 r / min and a maximum speed of 150,000 r / min. The radial bearing employs a semi-floating floating ring bearing structure, using ball bearings to restrict the free rotation of the floating ring, forming a compression damping oil film to enhance high-speed operational stability. High-voltage leads are routed through glass-bonded connectors, with a withstand pressure of no less than 4MPa. The cooling system integrates motor and compressor cooling, with spiral grooves forming spiral cooling channels on the inner wall of the motor housing. This invention offers advantages such as small size, light weight, high integration, high efficiency, and high reliability, making it suitable for heat pump compressor scenarios in the thermal management systems of new energy commercial vehicles.

[0028] Specifically, the centrifugal compressor body adopts an open machined flow channel and a bladeless parallel diffuser surface, combined with a three-dimensional twisted blade pressure roller. The surface roughness of the machined flow channel is better than that of the cast shell, which improves the isentropic compression efficiency by 1% to 3%; the axial clearance between the pressure roller and the pressure shell is controlled at 0.07 to 0.15 mm, which is more than 50% smaller than the air flotation scheme, further improving the isentropic efficiency by 2% to 3%; the bladeless diffuser significantly reduces the processing cost.

[0029] Specifically, the motor assembly uses a sensorless permanent magnet synchronous motor driven by SVPWM; six strands of 0.45mm fine wire are wound in parallel, effectively reducing high-frequency copper losses. The rotor adopts a segmented sheath interference fit, applying radial preload to the magnets to prevent the NdFeB magnets from breaking and falling off due to excessive centrifugal tensile stress under operating conditions above 140,000 rpm.

[0030] The stator integral epoxy resin potting replaces the traditional varnish impregnation (VPI) process, which has three key advantages: ① The thermal conductivity is increased to over 1.0 W / (m·℃), and the winding temperature rise is reduced by 10% to 20%. According to the Arrhenius law of insulation thermal aging, it can significantly extend the insulation life; ② The protection level reaches IP67, which effectively prevents the refrigerant liquid and lubricating oil from corroding the winding insulation; ③ The winding is cured into a whole, resisting the fatigue loosening of the conductor caused by vehicle vibration, and the insulation withstand voltage is ≥3000V.

[0031] The system supports a wide voltage range of 450 to 850VDC and is compatible with the 600V / 850V dual-voltage platform for new energy commercial vehicles.

[0032] Specifically, the radial bearing adopts a semi-floating floating ring structure: a hydrodynamic support oil film is formed on the inner side, and a squeeze film damping oil film is formed on the outer side. The ball 14 limiting mechanism prevents the floating ring from rotating freely, transforming the fully floating rotating hydrodynamic film into a pure squeeze film damping film, effectively suppressing oil film eddy and oscillation, achieving high-speed stable operation above 120,000 rpm, and significantly enhancing its resistance to vehicle impact.

[0033] The requirements for machining accuracy of extrusion damping oil film are much lower than those of fully floating hydrodynamic oil film. Aluminum alloy can be used to replace cast iron for bearing support (its density is about 1 / 3 that of cast iron and its thermal conductivity is better). The gap change caused by thermal expansion is within the allowable range, which greatly reduces weight and manufacturing cost.

[0034] The thrust bearing 7 uses a wedge-shaped oil film bearing, and the axial movement is controlled within 0.06 to 0.10 mm, which is less than half of that of the air bearing scheme. This ensures that the clearance between the pressure roller and the pressure shell is controlled within 0.1 to 0.15 mm, further improving the compression efficiency.

[0035] The lubricating oil used is POE32, which is compatible with mainstream low-GWP refrigerants such as R134a, R1234yf, R290, and CO2. It has a high electrical breakdown voltage, is compatible with the internal materials of the motor, and is suitable for high-pressure sealed cavity environments.

[0036] Furthermore, the bearing system includes two radial bearings and a thrust bearing 7. The two radial bearings adopt a semi-floating floating ring bearing structure. The semi-floating floating ring bearing system is specially designed for high-pressure refrigerant sealing working environment. The system working pressure can reach more than 3MPa. The bearings are immersed in POE32 lubricating oil that is compatible with high-pressure refrigerant for a long time. The bearing cavity is completely isolated from the high-pressure refrigerant pipeline. A dynamic pressure inner oil film is formed between its inner circular surface and the outer circle of the shaft, which supports the rotor shaft 10 to float. A compression damping outer oil film is formed between its outer circular surface and the inner surface of the bearing support hole, which is used to absorb the vibration of the rotor during high-speed operation, improve the impact resistance under vehicle impact conditions, and support the rotor to operate stably at high speeds above 120,000 rpm. The gap size of the inner and outer oil films and the bearing material are determined by simulation calculation and experimental verification based on the dynamic viscosity parameters of POE32 lubricating oil.

[0037] The radial bearing is constrained to rotate freely by anti-rotation ball bearings 14; the cooling system adopts an integrated design of motor cooling and compressor cooling; the sealing structure includes glass sintered connector 18 for sealing the high-voltage lead.

[0038] Furthermore, the system uses ISO VG32 grade polyester (POE32) lubricant, selected for the following reasons: First, POE32 exhibits good miscibility and chemical thermal stability with mainstream low-GWP refrigerants such as R1234yf (GWP≈4), R290 (GWP≈3), R744 (CO2, GWP=1), and R134a, enabling long-term use within high-pressure refrigerant cavities without deterioration. Second, POE32 has an electrical breakdown voltage of not less than 25kV and a low dielectric constant, making it suitable for use within high-voltage permanent magnet synchronous motor cavities. It also demonstrates good compatibility with H-class insulated enameled wire, integral potting materials, and internal motor materials such as copper and stainless steel, without corroding or eroding the insulation layer. Third, ISO VG32... The VG32 viscosity grade exhibits suitable dynamic viscosity within the compressor's operating temperature range (-40~120℃), meeting the hydrodynamic lubrication requirements of the radial bearings and thrust bearing 7. The bearing clearances, bearing diameters, effective lengths, spans of the two radial bearings, and the number and dimensions of the wedge surfaces of the thrust bearing 7 are all determined based on the dynamic viscosity parameters of POE32 lubricating oil within the operating temperature range, combined with rotor shaft modal analysis, stability analysis, load-bearing capacity simulation calculations, and experimental verification. Specifically, the sensorless permanent magnet synchronous motor driven by SVPWM has an operating voltage range of 450 to 850 VDC, a rated speed of 140,000 rpm, a maximum speed of 150,000 rpm, and a rated power of 8 kW.

[0039] Specifically, the spiral grooves on the inner wall of the motor housing and the outer surface of the stator core in the cooling system together form a spiral cooling channel, realizing an integrated cooling design for the motor and compressor, which has high heat dissipation efficiency and good structural integration.

[0040] Specifically, in the sealed structure, the high-voltage lead is led out through the glass sintered connector 18, with a withstand pressure ≥4MPa, which meets the long-term sealing and insulation requirements under high-pressure refrigerant environment.

[0041] The shaft seal adopts the end face piston ring 19 sealing scheme: the piston ring 19 uses the high-pressure refrigerant gas after compression to form a "self-pressurizing" sealing effect - the higher the system pressure, the stronger the sealing contact force, effectively isolating the refrigerant compression pipeline and the lubrication oil pipeline, ensuring that the two media are independent of each other.

[0042] Specifically, the centrifugal compressor body includes a pressure shell 1 and a pressure roller 3. A gas flow channel for refrigerant compression is formed inside the pressure shell 1. The pressure roller 3 is located inside the pressure shell 1 and is used for centrifugal compression of the refrigerant. The axial clearance between the pressure roller 3 and the pressure shell 1 is 0.07mm to 0.15mm. The motor assembly includes a motor housing 8 and a motor armature 9 that is interference-fitted with the motor housing 8 and is used to drive the pressure roller 3 to rotate. The bearing system includes a first radial bearing 121, a second radial bearing 122, and a thrust bearing 7. The first radial bearing 121 and the second radial bearing 122 are connected to the rotor shaft 10. The rotor shaft 10 adopts a segmented assembly structure. The thrust bearing 7 is located at the end of the rotor shaft 10 and is used to bear the axial thrust load. The cooling system includes a spiral cooling groove 802 located on the inner wall of the motor housing 8. Spiral groove inlet and outlet ports 801 are provided at both ends of the spiral cooling groove 802, including designed inlet and outlet ports. After the motor armature 9 is installed, the outer surface of the motor armature 9 and the spiral cooling groove 802 together form a spiral cooling gas channel.

[0043] Specifically, depending on the actual layout requirements, the air inlet and exhaust ports can be interchanged. The air inlet connects to the condensed refrigerant gas, and the refrigerant flow is controlled by an expansion valve or a fixed throttle valve to regulate the motor temperature. The exhaust port connects to the cooling circuit of the electronic control device or the inlet of the gas-liquid separator, and participates in the refrigerant circulation. The refrigerant does not come into contact with the oil circuit to ensure that the refrigerant does not permeate into the oil gas.

[0044] Specifically, the top of the motor housing 8 is provided with an oil inlet hole, which is branched through a pipeline to vertical oil passages on both sides, and then the lubricating oil is delivered to the oil storage tank at the top of the first radial bearing 121 through an inclined hole; oil holes 21 are evenly distributed in the oil storage tank to deliver the lubricating oil to the gap between the inner diameter of the first radial bearing 121 and the rotor shaft 10; the oil passage near the pressure roller 3 is provided with a branch leading to the thrust bearing 7 to supply oil to the thrust bearing 7; and an oil return passage is provided below the first radial bearing 121.

[0045] It also includes a locking nut 2, which is used to fix the pressure roller 3 to the motor shaft end.

[0046] Furthermore, it also includes a bearing cover 6, one end of which presses against the thrust bearing 7. The outer surface of the bearing cover 6 and the inner bottom surface of the pressure shell 1 cooperate to form a disc-shaped expansion cavity. The other side of the bearing cover 6 presses against the thrust bearing 7 to limit the axial movement of the thrust bearing 7. A sealing ring groove is provided on the outer circular surface of the bearing cover 6, and a sealing ring is installed inside it to prevent lubricating oil from leaking into the refrigerant compression pipeline.

[0047] Furthermore, the pressure shell 1 adopts a non-closed open machined flow channel design; the inner wall of the pressure shell 1 forms a bladeless diffuser surface with parallel spacing between the end faces of the motor housing 8 and the bearing cover 6, which is used to convert the kinetic energy of the compressed gas into pressure potential energy.

[0048] Furthermore, it also includes a shaft seal 4, one side of which abuts against the back of the pressure roller 3, and the other side abuts against the thrust plate 5; the shaft seal 4 has a piston ring groove on the side near the pressure roller 3, and the piston ring 19 is assembled in the piston ring groove; the elastic tension of the piston ring 19 keeps it in initial radial sealing contact with the outer surface of the rotor shaft 10; after compression, the high-pressure refrigerant gas acts on the back of the piston ring 19, increasing the sealing contact pressure and forming a self-pressurizing sealing effect that is adaptively enhanced with the working pressure. When the rotor shaft 10 rotates at high speed, a dynamic oil film is formed between the piston ring 19 and the shaft surface, providing lubrication and assisting in sealing, thereby preventing lubricating oil from seeping into the refrigerant compression channel.

[0049] Furthermore, the thrust plate 5 and the shaft seal 4 are fixed at a distance L1, which is 0.06 to 0.10 mm greater than the height of the thrust bearing 7, so that the axial movement of the rotor shaft 10 is controlled within the range of 0.06 to 0.10 mm.

[0050] Furthermore, it also includes a thrust plate 5, which is attached to the other side of the shaft seal 4, and the thrust plate 5 is matched with the thrust bearing 7.

[0051] Furthermore, the thrust bearing 7 has two openings, which are asymmetrically arranged. Thrust bearing positioning pins 20 are installed in the two openings to radially limit the thrust bearing 7. The thrust bearing 7 has multiple wedge-shaped surfaces.

[0052] Specifically, the thrust bearing 7 has wedge-shaped surfaces on both ends, and fine holes communicating with the bottom of the wedge-shaped surfaces are provided on the thrust bearing 7. Lubricating oil is supplied to the wedge-shaped surfaces through the oil passage to form a bearing oil film.

[0053] Specifically, the lower part of the wedge-shaped surface has oil holes leading to a common oil passage. The oil passage is formed by a strip of grooves on the bearing end face mating with the flat part of the front bearing support 803. The front bearing support 803 has oblique holes communicating with external oil passages, thereby providing lubricating oil to the thrust bearing 7.

[0054] Furthermore, a front-end bearing support 803 is integrated inside the motor housing 8, which is used to install the first radial bearing 121; a rear-end bearing support 11 is fixedly connected to the rear end of the motor housing 8, which is used to install the second radial bearing 122; an oil reservoir is provided between the outer sides of the first radial bearing 121 and the second radial bearing 122, and oil holes 21 are evenly distributed in the oil reservoir to deliver lubricating oil to the inner diameter of the bearing 12.

[0055] Specifically, the first radial bearing 121 is constrained in the bearing mounting hole of the front bearing support 803 by means of retaining rings 13 on both sides or one step on each side. The second radial bearing 122 is constrained in the bearing mounting hole of the rear bearing support 11 by means of retaining rings 13 on both sides or one step on each side. The first radial bearing 121 and the second radial bearing 122 can move slightly axially within the holes.

[0056] Furthermore, the arrangement positions of the front bearing support 803 and the rear bearing support 11 can be flexibly configured according to the actual installation boundary requirements. The front bearing support 803 is integrated with the motor housing 8, while the other is an independent rear bearing support 11. The two can be arranged on the side near the rotor shaft pressure wheel end 101 or the side near the rotor shaft support end 104, respectively, to adapt to different overall machine structure layout requirements. The upper end of each bearing support hole is provided with an oil hole channel to deliver lubricating oil to the outside of the first radial bearing 121 or the second radial bearing 122. There is a gap between the outside of the first radial bearing 121 or the second radial bearing 122 and the bearing seat hole. An oil reservoir is provided in the middle of the outside of the first radial bearing 121 or the second radial bearing 122. Oil holes 21 are evenly distributed in the oil reservoir to deliver lubricating oil to the inner diameter of the first radial bearing 121 or the second radial bearing 122.

[0057] Furthermore, the outer circular surface of the first radial bearing 121 is provided with a semi-circular groove, and the inner hole of the bearing support connected to the first radial bearing 121 is provided with a corresponding semi-circular groove. The two semi-circular grooves are joined together to form a cylindrical hole, and a ball 14 with the same inner diameter as the cylindrical hole is embedded in the cylindrical hole. One side of the ball 14 abuts against the stepped surface of the bearing 12 and the bearing support, and a retaining ring 13 is provided on the other side to limit the ball 14. The ball 14 is used to constrain the free rotation of the first radial bearing 121, so that it changes from a fully floating ring bearing to a semi-floating ring bearing.

[0058] If the radial bearing is not constrained to rotate freely, it will form a fully floating ring bearing. When operating in an unstable speed range below 120,000 rpm, the floating ring may rotate freely at about 0.4 to 0.5 times the shaft speed. The outer oil film is prone to half-frequency whirl. When the whirl frequency approaches the natural frequency of the rotor system, it will cause oil film oscillation, resulting in a sharp increase in amplitude and endangering system safety. The semi-floating design constrains the rotation of the floating ring through the ball bearing 14, fundamentally eliminating the whirl excitation source of the outer oil film and suppressing the occurrence of oil film whirl and oil film oscillation. The above-mentioned ball bearing 14 solution is a simple and low-cost way to prevent the free rotation of the floating ring bearing. In addition to the ball bearing 14, thrust bearing positioning pins 20 or elastic baffles can also be used to embed between the outer surface of the radial bearing and the inner hole of the front bearing support 803 or the rear bearing support 11, or a groove can be set on the bearing end face to contact the elastic baffle. All of these methods can achieve the effect of preventing the free rotation of the floating ring bearing and achieving the function of a semi-floating bearing. The choice can be made according to the actual processing conditions and spatial layout. Since the requirements for the oil film gap accuracy of the extrusion damping outer oil film are much lower than those of the fully floating floating ring dynamic pressure oil film, the front face bearing support 803 or the rear face bearing support 11 can be made of aluminum alloy material, without being limited to materials such as cast iron with low thermal expansion coefficient; aluminum alloy bearing supports have advantages such as low density, low machining cost and good thermal conductivity, which can further reduce manufacturing costs and reduce the weight of the whole machine while meeting the extrusion damping function.

[0059] Furthermore, the rotor shaft 10 includes a rotor shaft pressure roller end 101, a permanent magnet 102, a magnet sleeve 103, and a rotor shaft support end 104; the magnet sleeve 103 radially clamps the rotor shaft pressure roller end 101, the permanent magnet 102, and the rotor shaft support end 104 together to form an integral rotor assembly through an interference fit.

[0060] Preferably, the magnet sleeve 103 is made of high-nickel alloy. The magnet sleeve 103 applies radial preload to the permanent magnet 102 to counteract the centrifugal tensile stress during ultra-high speed rotation, preventing the permanent magnet 102 from breaking or falling off. The rotor shaft pressure roller end 101 passes through the first radial bearing 121 near the pressure roller 3. Its outer end is sequentially equipped with a thrust plate 5, shaft seal 4, pressure roller 3 and locking nut 2. The rotor shaft support end 104 passes through the second radial bearing 122 away from the pressure roller 3. The permanent magnet 102 rotates at high speed under the action of the stator magnetic field of the motor armature 9, driving the entire rotor assembly to rotate.

[0061] Specifically, the magnet sheath 103 is made of a material that simultaneously meets the requirements of high strength and non-magnetic properties: preferably GH4169 nickel-based high-temperature alloy (i.e., Inconel). 718), this alloy is a paramagnetic material in the annealed and aged state, with a relative permeability μr≈1.001 and an aged tensile strength of not less than 1380MPa, which will not provide a leakage magnetic path for the permanent magnet 102, while meeting the strength requirements of the high-speed sheath; carbon fiber composite material can also be used, which also has the characteristics of non-magnetic and high specific strength; the rotor shaft pressure wheel end 101 and the rotor shaft support end 104 are preferably made of GH4169 alloy; if ferromagnetic high-strength structural steel such as 42CrMo is used, magnetic isolation rings made of GH4169 or austenitic stainless steel must be inserted between the two end faces of the permanent magnet 102 and the shaft end to cut off the leakage magnetic path at the shaft end; the interference of the magnet sheath 103 is determined by calculation based on the maximum centrifugal stress on the magnet at the highest speed (150,000 rpm), to ensure that the preload of the sheath on the magnet is always greater than the centrifugal tensile stress on the magnet.

[0062] Specifically, the stator winding of the motor armature 9 adopts a 12-slot single-layer lap winding structure with a single-pole logarithmic design and a rated operating frequency of 2333Hz. The stator winding uses six 0.45mm diameter enameled wires wound in parallel to reduce AC copper losses caused by the skin effect under high-frequency conditions. The enameled wire uses the corona-resistant Q(ZY / XY)BP-2 / 200 specification to cope with inter-turn high-frequency corona corrosion caused by SVPWM high-frequency modulation. The stator core and windings adopt an integral resin potting process to completely encapsulate and seal the stator armature. The thermal conductivity of the potting resin is not less than 1W / (m·℃), which is more than 4 times higher than the thermal conductivity of the traditional impregnation process, which is usually only 0.15~0.25W / (m·℃). This effectively eliminates the air thermal resistance between windings and can reduce the winding temperature rise by 10%~20%, according to the insulation thermal aging Arrhenius... The law (insulation life doubles for every 10°C decrease in temperature) significantly extends the service life of the motor; after potting, the stator forms a sealed solid whole with a protection level of not less than IP67, providing protection against water, refrigerant liquids, and POE lubricating oil corrosion, while also improving the mechanical integrity of the windings to resist wire fatigue and loosening caused by high-speed rotation and vehicle vibration; the potting insulation withstand voltage is not less than 3000V, and the winding-to-ground insulation resistance is not less than 500MΩ; the motor is equipped with a PT1000 temperature sensor for real-time monitoring of motor temperature, suitable for wide temperature range vehicle operating conditions of -40 to 85°C.

[0063] Furthermore, it also includes a sealing structure, including a glass sintered connector 18, with a connector 15, an adapter block cover 16 and an electrical adapter block 17 provided on the outer end of the glass sintered connector 18. The outer end of the glass sintered connector 18 is sealed for sealing the high-voltage lead wire.

[0064] In another embodiment, the rotor shaft support end 104 extends outward after passing through the second radial bearing 122, and its end is sequentially fitted with another pressure roller 3 and another locking nut 2. The other pressure roller 3 is placed in the corresponding other pressure shell, and together with the pressure roller 3 on the side of the rotor shaft pressure roller end 101, it forms a two-stage series centrifugal compression structure. The gas outlet of the pressure shell 1 is connected to the gas inlet of the other pressure shell through an intermediate connecting pipe. After the refrigerant gas is compressed and pressurized by the first-stage pressure roller 3, it is guided to the inlet of the other second-stage pressure roller through the intermediate connecting pipe. The other second-stage pressure roller performs centrifugal compression again, and finally outputs high-pressure refrigerant from the outlet of the other pressure shell. The intermediate connecting pipe can be directly connected or introduced after buffering through the intermediate cavity, depending on the overall layout. Compared with single-stage compression, two-stage series compression can significantly improve the total pressure ratio of the system, which is especially suitable for the high pressure ratio requirement at low ambient temperatures in the heating operation of heat pump systems, thereby improving the heating capacity and coefficient of performance (COP) of the system.

[0065] Under heat pump heating conditions, the system can be expanded into a two-stage series centrifugal compression structure: the second-stage pressure roller is installed at the extension end of the rotor shaft, and the total pressure ratio of the two stages can reach more than 5.0, which greatly improves the low-temperature heating capacity and heating COP.

[0066] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A miniature high-speed centrifugal refrigerant compressor system, characterized in that, This includes the centrifugal compressor body, motor assembly, bearing system, and cooling system; The centrifugal compressor body includes a pressure shell (1) and a pressure wheel (3), and a gas flow channel for refrigerant compression is formed inside the pressure shell (1); The pressure roller (3) is disposed inside the pressure shell (1) and is used to centrifugally compress the refrigerant. The axial gap between the pressure roller (3) and the pressure shell (1) is 0.07mm to 0.15mm. The motor assembly includes a motor housing (8) and a motor armature (9) that is interference-fitted with the motor housing (8) for driving the pressure roller (3) to rotate; The bearing system includes a first radial bearing (121), a second radial bearing (122), and a thrust bearing (7). The first radial bearing (121) and the second radial bearing (122) are connected to the rotor shaft (10). The rotor shaft (10) adopts a segmented assembly structure. The thrust bearing (7) is located at the end of the rotor shaft (10) and is used to bear the axial thrust load. The cooling system includes a spiral cooling groove (802) disposed on the inner wall of the motor housing (8). The spiral cooling groove (802) has an air inlet and an exhaust port at both ends. After the motor armature (9) is installed, the outer surface of the motor armature (9) and the spiral cooling groove (802) together form a spiral cooling air channel.

2. The miniature high-speed centrifugal refrigerant compressor system according to claim 1, characterized in that, It also includes a bearing cover (6), one end of which presses against the thrust bearing (7), the outer surface of the bearing cover (6) and the inner bottom surface of the pressure shell (1) form a disc-shaped expansion cavity, and the other side of the bearing cover (6) presses against the thrust bearing (7) to limit the axial movement of the thrust bearing (7).

3. The miniature high-speed centrifugal refrigerant compressor system according to claim 1, characterized in that, The pressure shell (1) adopts a non-closed open machined flow channel design; the inner wall of the pressure shell (1) forms a bladeless diffuser surface with parallel spacing between the end faces of the motor housing (8) and the bearing cover (6), which is used to convert the kinetic energy of the compressed gas into pressure potential energy.

4. The miniature high-speed centrifugal refrigerant compressor system according to claim 1, characterized in that, It also includes a shaft seal (4), one side of which abuts against the back of the pressure roller (3) and the other side abuts against the thrust plate (5); the shaft seal (4) has a piston ring groove on the side near the pressure roller (3), and the piston ring (19) is assembled in the piston ring groove; The elastic tension of the piston ring (19) keeps it in initial radial sealing contact with the outer surface of the rotor shaft (10); the thrust plate (5) and the shaft seal (4) define a fixed distance L1, the distance of L1 being 0.06 to 0.10 mm greater than the height of the thrust bearing (7), so that the axial movement of the rotor shaft (10) is controlled within the range of 0.06 to 0.10 mm.

5. A miniature high-speed centrifugal refrigerant compressor system according to claim 4, characterized in that, It also includes a thrust plate (5), which is attached to the other side of the shaft seal (4) and the thrust plate (5) cooperates with the thrust bearing (7).

6. The miniature high-speed centrifugal refrigerant compressor system according to claim 1, characterized in that, The thrust bearing (7) has two openings, which are asymmetrically arranged. The thrust bearing positioning pin (20) is installed in the two openings to radially limit the thrust bearing (7). The thrust bearing (7) has multiple wedge-shaped surfaces.

7. A miniature high-speed centrifugal refrigerant compressor system according to claim 1, characterized in that, The motor housing (8) integrates a front face bearing support (803), which is used to install the first radial bearing (121). The rear end of the motor housing (8) is fixedly connected to the rear end face bearing support (11), which is used to install the second radial bearing (122). An oil storage groove is provided in the middle of the outer side of the first radial bearing (121) and the second radial bearing (122). Oil holes (21) are evenly distributed in the oil storage groove to deliver lubricating oil to the inner diameter of the bearing (12).

8. A miniature high-speed centrifugal refrigerant compressor system according to claim 1, characterized in that, The outer surface of the first radial bearing (121) is provided with a semi-circular groove, and the inner hole of the bearing support connected to the first radial bearing (121) is provided with a corresponding semi-circular groove. The two semi-circular grooves are joined together to form a cylindrical hole, and a ball (14) with the same diameter as the inner diameter of the cylindrical hole is embedded in the cylindrical hole. The ball (14) abuts against the stepped surface of the bearing (12) and bearing support on one side, and a retaining ring (13) is provided on the other side to limit the movement of the ball (14). The ball (14) is used to constrain the free rotation of the first radial bearing (121).

9. A miniature high-speed centrifugal refrigerant compressor system according to claim 1, characterized in that, The rotor shaft (10) includes a rotor shaft pressure wheel end (101), a permanent magnet (102), a magnet sheath (103), and a rotor shaft support end (104). The magnet sheath (103) radially clamps the rotor shaft pressure wheel end (101), the permanent magnet (102) and the rotor shaft support end (104) into an integral rotor assembly through an interference fit.

10. The miniature high-speed centrifugal refrigerant compressor system according to any one of claims 1-9, characterized in that, It also includes a sealing structure, including a glass sintered connector (18), with a connector (15), an adapter block cover (16) and an electrical adapter block (17) provided on the outer end of the glass sintered connector (18), and the outer end of the glass sintered connector (18) is sealed for sealing the high voltage lead.

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