An azeotrope phase change cooling rotor assembly and roots compressor, vacuum pump

Abstract

This invention discloses an azeotropic phase change cooling rotor assembly, a Roots compressor, and a vacuum pump. The rotor assembly includes a main rotor with circumferentially shaped through-holes and an axially oriented internal through-hole on the rotor shaft. A first and a second auxiliary rotor are mounted at both ends of the main rotor. Rotor sealing plates are arranged on the inner sides of the two auxiliary rotors to seal the shaped through-holes and form a first azeotropic flow region. One end of the rotor shaft is connected to a drive motor, and the other end connects to a swirl cooling pipe with swirl fins on its outer wall, forming a second azeotropic flow region through end sealing. The first and second azeotropic flow regions are filled with an azeotropic phase change cooling medium. This invention is based on the azeotropic phase change heat transfer principle and combines a swirl cooling structure to achieve efficient heat dissipation. The overall structure is simple and compact, eliminating the need for complex cooling equipment, effectively suppressing rotor temperature rise during operation, and avoiding rotor jamming caused by high-temperature thermal expansion.

Description

Technical Field

[0001] This invention relates to the field of fluid machinery technology, specifically to an azeotropic phase change cooled rotor assembly and a Roots compressor and vacuum pump. Background Technology

[0002] Roots compressors or vacuum pumps are widely used in semiconductors, photovoltaics, vapor compression, petrochemicals, nuclear power, aerospace, and large scientific facilities due to their adaptability to harsh processes, low maintenance costs, and high pumping speed. The structure of a Roots compressor or vacuum pump mainly includes two figure-eight shaped, vertically arranged rotor assemblies, a matching housing, end covers, a drive motor, sealing components, and cooling components. The motor drives the rotor assemblies to rotate, achieving gas transport and compression. However, the heat generated by the isochoric compression of the gas in a Roots compressor or vacuum pump causes thermal expansion of the rotors and housing. This thermal expansion reduces the actual clearance between rotors, between the rotor and housing, and between the rotor and end covers. This can lead to rotor jamming in high-pressure differential conditions or harsh processes involving particles. Therefore, suppressing the thermal expansion of the rotor and housing is an effective way to improve the reliability of Roots compressors or vacuum pumps.

[0003] Common cooling methods for current Roots compressors or vacuum pumps include water jacket cooling, forced air cooling, and counter-current cooling. Water jacket cooling typically involves installing a water jacket outside the casing, using circulating cooling water to remove heat from the casing surface, indirectly cooling the rotor. Forced air cooling uses fans and other components to force airflow, accelerating heat dissipation from the casing and rotor surfaces. Counter-current cooling uses a counter-current heat exchange medium to cool the components. Additionally, for example, Chinese patent CN118881557B discloses "A Rotor Temperature Control System and Method for a Roots Vacuum Pump," which uses a wireless temperature sensor to measure the temperature of the rotor assembly and simultaneously cools the hollow rotor through a cooling circulation system to control the rotor temperature. Another example is Chinese patent CN223881356U, which discloses "A Roots Blower with a Dual Oil Pump Circulation Cooling Device," which uses two independently operating oil pumps to precisely lubricate and cool the bearings of the Roots blower.

[0004] Existing cooling solutions struggle to achieve simple and efficient differentiated cooling within the rotor. During rotation, the heat intensity varies significantly across different parts of the rotor assembly. For instance, the meshing areas and the contact area between the rotor end and the end cover are heated much more than other parts of the rotor. Existing cooling solutions either provide uniform cooling to the entire rotor, failing to target high-heat areas and resulting in low cooling efficiency and poor thermal expansion suppression, or require complex cooling pipelines, temperature measurement, and control components. These solutions are structurally complex, costly, and difficult to maintain, making them unsuitable for miniaturized, low-cost applications. Furthermore, they struggle to balance cooling effectiveness with equipment operational stability, failing to fundamentally solve the technical challenge of rotor jamming under high pressure differentials and stringent processes. This limits the application of Roots compressors or vacuum pumps in high-end, demanding environments. Summary of the Invention

[0005] The purpose of this invention is to address the problems in the prior art by providing an azeotropic phase change cooling rotor assembly and a Roots compressor and vacuum pump. Phase change cooling is achieved through the filling of an azeotropic medium, eliminating the need for complex structures, effectively avoiding rotor jamming caused by thermal expansion, and significantly improving the reliability and lifespan of the Roots compressor or vacuum pump.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, an azeotropic phase change cooling rotor assembly is provided, including a main rotor, wherein a contoured through hole is provided circumferentially inside the main rotor body, and an internal through hole is provided axially inside the rotor shaft. A first auxiliary rotor and a second auxiliary rotor are installed at both ends of the main rotor. A first rotor sealing plate and a second rotor sealing plate are provided on the inner side of the first auxiliary rotor and the second auxiliary rotor. The first rotor sealing plate and the second rotor sealing plate seal both ends of the contoured through hole to form a first azeotropic flow region. One end of the rotor shaft is connected to the motor, and the other end is connected to the vortex cooling pipe; The swirl cooling tube includes a connecting tube with swirl fins on its outer wall. One end of the connecting tube is connected to the end of the rotor shaft, and the other end of the connecting tube and the rotor shaft are sealed to form a second azeotropic flow region. The first azeotropic flow region and the second azeotropic flow region are filled with azeotropic phase change cooling medium.

[0007] As a preferred embodiment, the azeotropic phase change cooling medium is a water-ethanol azeotropic mixture, which turns into a gaseous state when the temperature of the water-ethanol azeotropic mixture reaches its boiling point.

[0008] As a preferred embodiment, when the main rotor rotates, the liquid phase azeotropic phase change cooling medium or high-density component in the first azeotropic flow region accumulates at the tooth tip under the action of centrifugal force to form a liquid accumulation zone, which cools and exchanges heat at the rotor tooth tip; the gas phase azeotropic phase change cooling medium or low-density component in the first azeotropic flow region accumulates at the tooth bottom to form a gas accumulation zone, which cools and exchanges heat at the rotor tooth bottom.

[0009] As a preferred embodiment, the swirl cooling tube installation area forms a condensation heat exchange region. The azeotropic phase change cooling medium in the second azeotropic flow region conducts heat exchange with the azeotropic phase change cooling medium in the first azeotropic flow region and the weak convection region at the tooth root, forming an evaporation heat exchange two-phase region. The azeotropic phase change cooling medium in the second azeotropic flow region condenses in the condensation heat exchange region, and the condensate flows back to the evaporation heat exchange two-phase region to continuously cool the main rotor. Due to the rotation of the main rotor, in the evaporation heat exchange two-phase region, the liquid phase azeotropic phase change cooling medium or high-density component accumulates on the outer periphery of the shaft through hole under the action of centrifugal force, while the gas phase azeotropic phase change cooling medium or low-density component accumulates at the center of the shaft through hole.

[0010] As a preferred embodiment, the cross-sectional shape of the contoured through hole is similar to the outer circumferential profile of the main rotor, and a contoured filling float is provided inside the contoured through hole, the shape of which is similar to that of the contoured through hole.

[0011] As a preferred embodiment, the conformal filling float is divided into a first float block, a second float block, a third float block, and a fourth float block along the axial direction. Gaps are left between the four float blocks of the conformal filling float, between the conformal filling float and the conformal through hole, and between the conformal filling float and the first rotor sealing plate and the second rotor sealing plate.

[0012] As a preferred embodiment, a sealing plate mounting groove is provided on the end face of the main rotor, and a sealing plate mounting positioning groove is also provided on the outer periphery of the sealing plate mounting groove. The positioning parts of the first rotor sealing plate and the second rotor sealing plate are assembled into the sealing plate mounting positioning groove, and the first rotor sealing plate and the second rotor sealing plate are fixed on the sealing plate mounting groove by welding.

[0013] As a preferred embodiment, the swirl cooling tube achieves cooling through external air cooling, internal cooling, or internal oil spray cooling. The external air cooling method involves arranging the swirl cooling pipes outside the gearbox; The built-in cooling method involves arranging the swirl cooling tubes inside the gearbox and using the splashing oil mist inside the gearbox to cool the swirl cooling tubes. The built-in oil spray cooling method arranges the swirl cooling tubes inside the gearbox and uses a pipeline with circulating oil spray ports to directionally cool the swirl cooling tubes.

[0014] In a second aspect, a Roots compressor is provided, having the azeotropic phase change cooled rotor assembly.

[0015] Thirdly, a Roots vacuum pump is provided, having the azeotropic phase change cooled rotor assembly.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: The azeotropic phase change cooling rotor assembly proposed in this invention utilizes the contoured through holes arranged circumferentially around the main rotor and the axial through holes opened in the rotor shaft. These, along with the sealing of the first and second rotor sealing plates, form a first azeotropic flow region, and the end-sealed vortex cooling pipes form a second azeotropic flow region. Under high-speed rotor rotation, centrifugal force allows the liquid or high-density components of the azeotropic phase change cooling medium to accumulate at the high-temperature inter-tooth positions and the walls of the axial through holes. Simultaneously, the vortex cooling pipes with vortex fins enhance the condensation and heat dissipation effect, constructing a complete heat transfer path from the compressed gas of the Roots rotor, through the convection regions at the tooth top and bottom, the first azeotropic flow region, the heat conduction and heat transfer region, the second azeotropic flow region, the forced convection heat transfer region, and finally to the external environment. Heat is dissipated through conduction at each stage, thus achieving precise and efficient overall rotor cooling and solving the problem of high-temperature heat accumulation during Roots rotor operation. This invention achieves a sealed arrangement of the azeotropic phase change cooling medium by opening through holes inside the rotor body and shaft, and combining them with a sealing plate and a swirl cooling pipe. The overall component layout is compact and the cooling structure is simple, eliminating the need for complex cooling auxiliary equipment and significantly reducing the cost of later inspection and maintenance. At the same time, the simplified integrated structure facilitates modular and serialized design and production of the product, effectively improving the structural stability and reliability of the azeotropic phase change cooling rotor assembly during long-term operation.

[0017] Furthermore, the present invention incorporates a conformal filling float within the conformal through-hole. This conformal filling float is axially divided into four float blocks, with gaps between the four float blocks, between the conformal filling float and the conformal through-hole, and between the conformal filling float and the first and second rotor sealing plates, forming a floating fit structure. The use of a conformal filling float within the conformal through-hole effectively reduces the overall charge of the azeotropic phase change cooling medium, lowering application costs. Simultaneously, the multiple float blocks generate floating disturbances with the movement of the medium, actively agitating the internal medium flow field, promoting uniform flow of the azeotropic medium, enhancing the phase change heat transfer efficiency of the azeotropic phase change cooling medium, and improving overall cooling performance.

[0018] Furthermore, the swirl cooling tube of this invention is adaptable to three cooling modes: external air cooling, internal cooling, and internal oil spray cooling, offering flexible selection and strong adaptability. The internal cooling method utilizes the existing oil mist environment inside the gearbox for heat exchange. The gear oil agitator or oil slinger in the gearbox cools the bearings of the main rotor shaft extension section, and also cools the swirl cooling tube. The internal cooling method is highly compatible with the existing mainstream equipment structure, exhibiting excellent adaptability and facilitating direct modification and iteration based on existing rotor equipment, reducing product upgrade and modification costs, and enhancing the engineering applicability of the solution. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A schematic diagram of thermal deformation of the outer peripheral wall of a typical Roots compressor or vacuum pump rotor; Figure 2 A schematic diagram of the radial heat transfer mechanism of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 3 Schematic diagram of the axial heat transfer mechanism of the azeotropic phase change cooling rotor assembly in this invention; Figure 4 A schematic diagram of the radial heat transfer region of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 5 A schematic diagram of the axial heat transfer region of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 6 A schematic diagram of a 1 / 4 three-dimensional cross-sectional structure of an azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 7 A front view schematic diagram of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 8 A schematic diagram of the 1 / 4 three-dimensional cross-sectional structure of the main rotor of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 9 A schematic diagram of the contour-following filled float structure of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 10 A schematic diagram of the rotor sealing plate structure of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 11 A schematic diagram of the auxiliary rotor structure of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 12A schematic diagram of the swirl cooling tube structure of the azeotropic phase change cooling rotor assembly according to an embodiment of the present invention; Figure 13 Schematic diagram of the external air-cooled structure of the cyclone cooling tube in an embodiment of the present invention; Figure 14 Schematic diagram of the built-in cooling structure of the swirl cooling tube in an embodiment of the present invention; Figure 15 Schematic diagram of the built-in oil spray cooling structure of the swirl cooling tube in an embodiment of the present invention; In the attached diagram: 1-Main rotor; 11-Main rotor connecting screw hole; 12-Sealing plate mounting groove; 13-Sealing plate mounting positioning groove; 14-Contouring through hole; 15-Shaft inner through hole; 2-First auxiliary rotor; 3-Second auxiliary rotor; 31-Second auxiliary rotor connecting bolt hole; 32-Second auxiliary rotor shaft through hole; 33-Non-flat surface reserved groove; 4-Contouring filling float; 41-First float block; 42-Second float block; 43-Third float block; 44-Fourth float block; 5-Second rotor 51 - Sealing plate positioning arc; 6 - First rotor sealing plate; 7 - Connecting screw; 8 - Second sealing screw; 9 - First sealing screw; 10 - Swirl cooling tube; 101 - Swirl fins; 102 - Connecting pipe thread; F1 - First azeotropic flow region; F2 - Second azeotropic flow region; L1 - Rotor tooth tip; L2 - Rotor tooth root; QA - Strong convection region at tooth tip; QB - Weak convection region at tooth root; QC - Heat conduction and heat transfer region; QD - Forced convection heat transfer region. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, those skilled in the art can obtain other embodiments without creative effort.

[0022] In the description of this invention, it should be noted that the orientations or positional relationships are based on those shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] Evaporative heat exchange of cooling medium is the basic principle of refrigeration equipment. It utilizes the latent heat of phase change during the vaporization process of liquid cooling medium to absorb heat at the hot end, thereby achieving cooling of the hot end. This invention is also designed based on this basic principle, which will not be elaborated here.

[0024] Please see Figure 1 In typical Roots compressors or vacuum pump rotors, the radial thermal deformation at the rotor tooth tip is greater than that at the tooth root. Furthermore, because the wall boundary velocity at the rotor tooth tip is greater than that at the tooth root, the heat transfer coefficient between the tooth tip and the pumped gas is larger, resulting in a higher temperature at the rotor tooth tip than at the tooth root.

[0025] Please see Figures 2 to 5 This invention provides an azeotropic phase change cooling rotor assembly. A first azeotropic flow region F1 is provided inside the main rotor body, and a second azeotropic flow region F2 is provided inside the rotor shaft. An azeotropic phase change cooling medium is filled into the first azeotropic flow region F1 and the second azeotropic flow region F2.

[0026] In one possible implementation, the azeotropic phase change cooling medium in this embodiment is a water-ethanol azeotropic mixture. When the temperature of the azeotropic phase change cooling medium reaches its boiling point, it will turn into a gaseous state. At atmospheric pressure, the boiling point of water is 100°C, and the boiling point of ethanol is 78.1°C. When the mass fraction of ethanol is 95.6%, the azeotropic point of the water-ethanol azeotropic mixture is 78.2°C; when the mass fraction of ethanol is 50%, the azeotropic point is 81.5°C; and when the mass fraction of ethanol is 5%, the azeotropic point is 99.7°C. The density of water is 1 g / cm³. 3 The density of ethanol is 0.789 g / cm³. 3 .

[0027] Furthermore, in high-pressure differential applications of Roots compressors or vacuum pumps, azeotropic media with high azeotropic points can be selected, while in vacuum pump applications with auxiliary pumps, azeotropic media with low azeotropic points can be selected.

[0028] According to the design of this embodiment of the invention, due to the rotation of the rotor, the liquid azeotropic medium or high-density component in the first azeotropic flow region F1 accumulates at the tooth tip under the action of centrifugal force to form a liquid accumulation zone, which cools and exchanges heat with the rotor tooth tip. The gaseous azeotropic medium or low-density component accumulates at the tooth root to form a gas accumulation zone, which cools and exchanges heat with the rotor tooth root. The azeotropic medium in the first azeotropic flow region F1 can adapt well to the temperature distribution characteristics of the rotor. The liquid accumulation zone at the tooth tip performs convective heat exchange with the strong convection region QA at the tooth tip, and the gas accumulation zone at the tooth root performs convective heat exchange with the weak convection region QB at the tooth root.

[0029] Furthermore, the azeotropic phase change cooling medium in the second azeotropic flow region F2 exchanges heat with the azeotropic phase change cooling medium in the first azeotropic flow region F1 and the weak convection region at the tooth root of the main rotor, forming an evaporative heat exchange two-phase region. The azeotropic phase change cooling medium in the second azeotropic flow region F2 condenses in the condensation heat exchange region, and the condensate flows back to the evaporative heat exchange two-phase region to continuously cool the main rotor. Similarly, due to the rotation of the rotor, in the evaporative heat exchange two-phase region, the liquid phase azeotropic medium or high-density component accumulates on the outer periphery of the internal through-holes of the rotor shaft under the action of centrifugal force, while the gas phase azeotropic medium or low-density component accumulates in the center of the internal through-holes of the rotor shaft.

[0030] According to the above design of the embodiments of the present invention, the heat exchange scheme of the azeotropic phase change cooling medium realizes the heat flow path from the compressed gas, the convection region at the tooth tip and tooth root, the first azeotropic flow region F1, the heat conduction and heat exchange region, the second azeotropic flow region F2, the forced convection heat exchange region to the environment, thereby achieving effective cooling of the rotor.

[0031] Please see Figures 6 to 12 Specifically, the azeotropic phase change cooling rotor assembly of the present invention includes a main rotor 1. The main rotor 1 has a circumferential through hole 14 inside its body and an axial through hole 15 inside its rotor shaft.

[0032] A first auxiliary rotor 2 and a second auxiliary rotor 3 are installed at both ends of the main rotor 1. A first rotor sealing plate 6 and a second rotor sealing plate 5 are provided on the inner side of the first auxiliary rotor 2 and the second auxiliary rotor 3. The first rotor sealing plate 6 and the second rotor sealing plate 5 seal both ends of the contoured through hole 14 to form a first azeotropic flow region F1. One end of the rotor shaft is connected to the motor, and the other end is connected to the vortex cooling pipe 10; The swirl cooling tube 10 includes a connecting tube with swirl fins 101 on its outer wall. One end of the connecting tube is connected to the end of the rotor shaft. The other ends of the connecting tube and the rotor shaft are sealed by a first sealing screw 9 and a second sealing screw 8 to form a second azeotropic flow region F2. The first azeotropic flow region F1 and the second azeotropic flow region F2 are filled with azeotropic phase change cooling medium.

[0033] In one possible implementation, the first rotor sealing plate 6 and the second rotor sealing plate 5 are welded and sealed to the main rotor 1 to prevent leakage of the azeotropic medium in the first azeotropic flow region F1 during rotor rotation.

[0034] Taking the second rotor sealing plate 5 as an example, the sealing plate is placed in the sealing plate mounting groove 12, and the sealing plate positioning arc 51 and the sealing plate mounting positioning groove 13 are installed and positioned, and then circumferential spot welding is performed.

[0035] Taking the second auxiliary rotor 3 as an example, it has a non-flat surface reserved groove 33 to reserve space for the non-flat surface after spot welding, and at the same time, the end face surface of the second auxiliary rotor 3 is required to be smooth and flat. This ensures the sealing of the azeotropic phase change cooling medium in the main rotor 1, and also ensures the flatness of the end face of the complete rotor composed of the main rotor 1, the first auxiliary rotor 2, and the second auxiliary rotor 3.

[0036] In one possible implementation, the shape of the contoured through hole 14 in the main rotor 1 is similar to the shape of the outer periphery of the main rotor 1, and the shape of the contoured filling float 4 is similar to the shape of the contoured through hole 14.

[0037] The contour-following filler float 4 consists of four floats: a first float block 41, a second float block 42, a third float block 43, and a fourth float block 44. These floats are placed in the contour-following through-hole 14 in the main rotor 1. Gaps are left between the four floats of the contour-following filler float 4, between the contour-following filler float 4 and the contour-following through-hole 14, and between the contour-following filler float 4 and the rotor sealing plate 5 or 6 to ensure that the contour-following filler float 4 floats flexibly in the first azeotropic flow region F1.

[0038] The main function of the contour-filled float 4 is to occupy the volume in the first azeotropic flow region F1 to reduce the amount of azeotropic cooling medium charged. In addition, the floating design of the contour-filled float 4 is conducive to the flow of azeotropic medium in the first azeotropic flow region F1. At the same time, it increases the disturbance when the rotor rotates to enhance the heat exchange of the azeotropic cooling medium in the first azeotropic flow region F1.

[0039] In one possible implementation, the swirl cooling tube 10 is sealed to the end of the rotor shaft via a connecting pipe thread 102. Its outer wall has swirl fins 101 for condensing the azeotropic cooling medium inside the swirl cooling tube 10. The condensate flows naturally back to the evaporation heat exchange two-phase region under gravity to exchange heat with the rotor. In the evaporation heat exchange two-phase region, the gaseous azeotropic cooling medium that accumulates at the center of the through-hole 15 inside the rotor shaft enters the swirl cooling tube 10 for condensation heat exchange.

[0040] In one possible implementation, the main rotor 1 and the first auxiliary rotor 2, and the main rotor 1 and the second auxiliary rotor 3 are coaxially positioned by the main rotor 1 and fastened together by four radially symmetrically distributed connecting screws. The design profile parameters of the main rotor 1, the first auxiliary rotor 2, and the second auxiliary rotor 3 are completely identical, and a circular arc-shaped Roots rotor profile can be adopted.

[0041] Please see Figures 13 to 15 In this embodiment of the invention, the swirl cooling tube 10 achieves cooling through external air cooling, internal cooling, or internal oil spray cooling. The swirl cooling pipe 10 is arranged outside the gearbox using an external air cooling method; The built-in cooling method arranges the swirl cooling pipe 10 inside the gearbox, and uses the splashing oil mist inside the gearbox to cool the swirl cooling pipe 10; since the gear oil stirring or oil slinger in the gearbox will cool the bearing of the main rotor 1 shaft extension section, this will also cool the swirl cooling pipe 10 arranged inside the gearbox.

[0042] The built-in oil spray cooling method arranges the swirl cooling pipe 10 inside the gearbox and uses a pipeline with circulating oil spray ports to directionally cool the swirl cooling pipe 10.

[0043] Among them, the built-in cooling method is highly compatible with the structure of existing mainstream equipment, with excellent adaptability, making it easy to directly modify and iterate on the basis of existing rotor equipment, reducing the cost of product upgrade and transformation, and making the solution more applicable to engineering.

[0044] Another embodiment of the present invention provides a Roots compressor having the azeotropic phase change cooled rotor assembly.

[0045] Roots compressors are positive displacement twin-rotor rotary units, and their main structures include: (1) Main unit housing: includes air inlet, exhaust outlet and compression chamber, providing a sealed working space for rotor operation and accommodating a pair of meshing rotors.

[0046] (2) Dual rotor assembly: a pair of meshing Roots rotors (main rotor and driven rotor) with toothed structure, rotating synchronously in opposite directions, relying on the change of tooth groove volume to complete gas intake, compression and discharge.

[0047] (3) Rotor shaft and bearing assembly: Rotor shaft, support bearing and seal are provided at both ends of the rotor to support the rotor rotation and prevent media leakage and lubricating oil leakage.

[0048] (4) Transmission mechanism: synchronous gear, gearbox, coupling. The motor drives the main rotor through the coupling. The synchronous gear ensures precise meshing and contactless operation of the two rotors.

[0049] (5) Basic cooling / lubrication system: Conventional models mostly use water cooling, air cooling, gearbox splash lubrication or simple oil cooling for the casing, without an active phase change cooling structure inside the rotor.

[0050] In this embodiment, when the azeotropic phase change cooling rotor assembly is integrated into the Roots compressor, the original main rotor's external dimensions and meshing tooth profile are retained. A contoured through hole is machined around the main rotor body in the circumferential direction, and an internal through hole is opened axially inside the rotor shaft to serve as a basic channel for the flow of the azeotropic medium, which is fully compatible with the original compression chamber installation space.

[0051] The first auxiliary rotor and the second auxiliary rotor are assembled at both ends of the main rotor, and the first rotor sealing plate and the second rotor sealing plate are respectively set on the inner side. The sealing plates seal the two ends of the through hole to form the first azeotropic flow area, and the internal heat exchange cavity of the rotor is constructed without damaging the external meshing structure of the rotor.

[0052] One end of the main rotor shaft retains its original connection structure and is connected to the motor and transmission system. The other end of the shaft, which extends out of the gearbox, is connected to the swirl cooling pipe. A sealing structure is used to seal the connection pipe and the end of the shaft, forming a second azeotropic flow region.

[0053] A quantitative amount of azeotropic phase change cooling medium is injected into two connected azeotropic flow regions, and self-circulating heat exchange is achieved by relying on the centrifugal force generated by the rotor rotation and the phase change characteristics of the medium.

[0054] The swirl cooling tube can be flexibly installed in three ways according to the overall layout requirements: external air cooling arranged on the outside of the gearbox, internal cooling placed inside the gearbox using oil mist heat exchange, and internal oil spray cooling combined with the gearbox circulating oil circuit. It can be directly adapted to the existing gearbox structure, realizing rapid assembly and iterative transformation of the whole machine.

[0055] Simultaneously, a conformal filling float can be matched and assembled in the rotor conformal groove. Relying on the float floating and the structure optimizing the medium flow state, the entire cooling assembly is integrated into the rotor and shaft end, without interfering with the dual rotor meshing, gas compression process and the original transmission lubrication system.

[0056] Another embodiment of the present invention provides a Roots vacuum pump having the azeotropic phase change cooled rotor assembly.

[0057] Roots vacuum pumps are positive displacement vacuum pumps without internal compression. Their main structure includes: (1) Pump body housing: includes an air inlet chamber, an exhaust chamber, and a compression working chamber, which accommodates a pair of Roots rotors and provides a sealed cavity for gas transportation.

[0058] (2) Dual rotor mechanism: It is equipped with a main rotor and a driven rotor. The two rotors rotate synchronously in opposite directions. They rely on the change of tooth groove volume to complete the intake, delivery and exhaust. A large amount of compression heat and friction heat will be generated during the high-speed operation of the rotor.

[0059] (3) Rotary shaft and support components: The rotor is fixed at both ends with a rotating shaft, and is equipped with bearings, axial seals and radial seals to achieve rotational support and prevent gas leakage and lubricating oil backflow into the pump chamber.

[0060] (4) Gear transmission assembly: Synchronous gears are installed inside the gearbox to ensure that the gap between the two rotors is constant and there is no contact meshing; the motor drives the main rotor to run through the coupling.

[0061] (5) Lubrication and cooling system: The gearbox adopts splash lubrication / forced oil lubrication; traditional cooling is mostly water cooling of the pump body jacket and air cooling of the outer wall. The rotor body has no internal cooling structure. Long-term high temperature can easily lead to thermal expansion, smaller gap, jamming, and reduced life.

[0062] In this embodiment, when the azeotropic phase change cooling rotor assembly is integrated into the Roots vacuum pump, the original rotor shape, tooth profile and fitting clearance are retained. A contoured through hole is machined around the inside of the main rotor body in the circumferential direction. At the same time, an internal through hole is opened in the rotor shaft in the axial direction to serve as a heat exchange channel for the azeotropic medium to flow through, which is fully compatible with the original pump cavity installation space.

[0063] The first auxiliary rotor and the second auxiliary rotor are respectively assembled at both ends of the main rotor. The first rotor sealing plate and the second rotor sealing plate are respectively set on the inner side of the auxiliary rotor. The two sets of sealing plates seal and isolate the two ends of the through hole, forming a closed first azeotropic flow area, isolating the pump chamber gas, and ensuring that the cooling medium operates independently and in a closed manner.

[0064] One end of the rotor shaft retains the original structure and is connected to the drive motor via a coupling; the other end of the shaft extends out of the gearbox or is arranged inside the gearbox, and is fixedly connected to a swirl cooling pipe with swirl fins; the connecting pipe and the end of the shaft are sealed to form a closed second azeotropic flow region.

[0065] A quantitative azeotropic phase change cooling medium is injected into the connected first and second azeotropic flow regions. Relying on the centrifugal force generated by the high-speed rotation of the rotor when the Roots vacuum pump is working, combined with the heat absorption of the medium during phase change and the heat release during condensation, internal self-circulation heat exchange is achieved.

[0066] A conformal filling float is installed in the rotor conformal groove. The floating action of the float and the groove reduces the amount of medium filling. At the same time, the medium flow field is disturbed as the rotor rotates, which enhances the internal convective heat transfer effect.

[0067] The cyclone cooling tubes can be flexibly selected from three cooling methods according to the overall structure of the Roots vacuum pump: External air cooling: Located outside the gearbox, using natural / forced air convection for heat dissipation; Built-in cooling: Located inside the gearbox, it utilizes passive heat exchange through splashing oil mist within the gearbox; Built-in oil spray cooling: Combined with the gearbox's circulating oil circuit, forced cooling is achieved through spray pipes.

[0068] The built-in type can be directly adapted to the existing Roots vacuum pump gearbox structure without major modifications.

[0069] The entire cooling system is integrated inside the main rotor and at the end of the shaft, without affecting the meshing operation of the dual rotors, the gas delivery in the pump chamber, the synchronous gear transmission, or the original sealing and lubrication system.

[0070] This invention features a simple structure, low maintenance cost, high reliability, and good cooling effect, which is beneficial for the serial design and iterative upgrading of phase change cooled Roots rotor products.

[0071] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical details; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An azeotropic phase change cooling rotor assembly, characterized in that: Includes a main rotor (1), the main rotor (1) has a circumferential through hole (14) inside its body, and an axial through hole (15) inside its rotor shaft. The first auxiliary rotor (2) and the second auxiliary rotor (3) are installed at both ends of the main rotor (1). The first auxiliary rotor (2) and the second auxiliary rotor (3) are provided with a first rotor sealing plate (6) and a second rotor sealing plate (5) on the inner side. The first rotor sealing plate (6) and the second rotor sealing plate (5) seal the two ends of the contoured through hole (14) to form the first azeotropic flow region (F1). One end of the rotor shaft is connected to the motor, and the other end is connected to the swirl cooling pipe (10). The swirl cooling tube (10) includes a connecting tube with swirl fins (101) on its outer wall surface. One end of the connecting tube is connected to the end of the rotor shaft, and the other end of the connecting tube and the rotor shaft are sealed to form a second azeotropic flow region (F2). The first azeotropic flow region (F1) and the second azeotropic flow region (F2) are filled with azeotropic phase change cooling medium.

2. The azeotropic phase change cooling rotor assembly according to claim 1, characterized in that: The azeotropic phase change cooling medium is a water-ethanol azeotropic mixture, which turns into a gaseous state when the temperature of the water-ethanol azeotropic mixture reaches its boiling point.

3. The azeotropic phase change cooling rotor assembly according to claim 1, characterized in that: When the main rotor (1) rotates, the liquid phase azeotropic phase change cooling medium or high-density component in the first azeotropic flow region (F1) accumulates at the tooth tip under the action of centrifugal force to form a liquid accumulation zone, which cools and exchanges heat at the rotor tooth tip; the gas phase azeotropic phase change cooling medium or low-density component in the first azeotropic flow region (F1) accumulates at the tooth bottom to form a gas accumulation zone, which cools and exchanges heat at the rotor tooth bottom.

4. The azeotropic phase change cooling rotor assembly according to claim 3, characterized in that: The installation area of ​​the swirl cooling tube (10) forms a condensation heat exchange area. The azeotropic phase change cooling medium in the second azeotropic flow area (F2) conducts heat exchange with the azeotropic phase change cooling medium in the first azeotropic flow area (F1) and the weak convection area at the tooth root to form an evaporation heat exchange two-phase area. The azeotropic phase change cooling medium in the second azeotropic flow area (F2) is condensed in the condensation heat exchange area. The condensate flows back to the evaporation heat exchange two-phase area to continuously cool the main rotor (1). Due to the rotation of the main rotor (1), in the evaporation heat exchange two-phase area, the liquid phase azeotropic phase change cooling medium or high-density component accumulates on the outer periphery of the shaft through hole (15) under the action of centrifugal force, and the gas phase azeotropic phase change cooling medium or low-density component accumulates in the center of the shaft through hole (15).

5. The azeotropic phase change cooling rotor assembly according to claim 1, characterized in that: The cross-sectional shape of the contoured through hole (14) is similar to the outer circumferential profile of the main rotor (1). A contoured filling float (4) is provided inside the contoured through hole (14). The shape of the contoured filling float (4) is similar to the shape of the contoured through hole (14).

6. The azeotropic phase change cooling rotor assembly according to claim 5, characterized in that: The contoured filling float (4) is divided into a first float block (41), a second float block (42), a third float block (43) and a fourth float block (44) along the axial direction. Gaps are left between the four float blocks of the contoured filling float (4), between the contoured filling float (4) and the contoured through hole (14), and between the contoured filling float (4) and the first rotor sealing plate (6) and the second rotor sealing plate (5).

7. The azeotropic phase change cooling rotor assembly according to claim 1, characterized in that: A sealing plate mounting groove (12) is provided on the end face of the main rotor (1), and a sealing plate mounting positioning groove (13) is also provided on the outer periphery of the sealing plate mounting groove (12). The positioning parts of the first rotor sealing plate (6) and the second rotor sealing plate (5) are assembled into the sealing plate mounting positioning groove (13), and the first rotor sealing plate (6) and the second rotor sealing plate (5) are fixed on the sealing plate mounting groove (12) by welding.

8. The azeotropic phase change cooling rotor assembly according to claim 1, characterized in that: The swirl cooling tube (10) achieves cooling through external air cooling, internal cooling, or internal oil spray cooling. The external air cooling method involves arranging the swirl cooling pipe (10) outside the gearbox; The built-in cooling method arranges the swirl cooling pipe (10) inside the gearbox and uses the splashed oil mist inside the gearbox to cool the swirl cooling pipe (10); The built-in oil spray cooling method arranges the swirl cooling pipe (10) inside the gearbox and uses a pipeline with circulating oil spray ports to directionally cool the swirl cooling pipe (10).

9. A Roots compressor, characterized in that, It has an azeotropic phase change cooling rotor assembly as described in any one of claims 1 to 8.

10. A Roots vacuum pump, characterized in that, It has an azeotropic phase change cooling rotor assembly as described in any one of claims 1 to 8.

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