Cooling structure of screw compressor and cooling method thereof

Abstract

This invention provides a cooling structure and method for a screw compressor, belonging to the field of compressor technology. The technical problem this invention aims to solve is to provide a compressor cooling structure that is simpler in structure, lower in cost, and more universal. This invention includes a volute, a screw assembly, and a star wheel. The screw assembly includes a screw shaft coaxially arranged and a screw fixed to the screw shaft. The screw has a hollow interior forming an inner cooling chamber. The screw assembly also has an inlet channel and an outlet channel. In use, both ends of the inner cooling chamber are closed. The two ends of the inlet channel connect the inside and outside of the inner cooling chamber, respectively, and the two ends of the outlet channel also connect the inside and outside of the inner cooling chamber, respectively. This solution has a simple structure, the cooling medium does not directly contact the compressor's compression chamber, and it is suitable for both oil-lubricated and dry-type compressors. It is applicable to various types of cooling media and can be configured according to actual needs, making it more universal.

Description

Technical Field

[0001] This invention belongs to the field of compressor technology, specifically referring to a cooling structure and cooling method for a screw compressor. Background Technology

[0002] Single-screw compressors, as a type of positive displacement rotary compressor, are widely used in compressed air supply, refrigeration and air conditioning, natural gas processing, food and pharmaceutical industries due to their advantages such as compact structure, good force balance, and low vibration. Their core working principle involves the meshing motion of the screw rotor and the star wheel assembly, causing the volume of the sealed compression chamber to change periodically, thereby achieving the intake, compression, and discharge of gas. Key structures typically include the screw, star wheel assembly, volute, and casing.

[0003] To prevent damage from contact between the star wheel assembly teeth and the screw groove, a gap is usually left between the edge of the star wheel assembly teeth and the inner wall of the screw groove. This gap is filled with lubricating oil for lubrication, sealing, and cooling. (For example, announcement number "...) A Chinese invention patent discloses a single-screw compressor, which consists of a housing, a cylinder, a screw, and a star wheel assembly. In this design, the single-screw compressor relies on oil injection for internal cooling to maintain a certain thermal balance so that the compressor can work normally. Therefore, a certain amount of oil needs to be injected into the machine, and the gaps are filled with oil. The oil can play a role in cooling, sealing, and lubrication.

[0004] Because this system requires oil injection for lubrication and cooling, the compressed air inevitably contains a certain amount of oil. To remove this oil, a precision filter is usually installed in the gas pipeline. However, while the precision filter can remove some oil, it cannot achieve a completely oil-free state, making the compressor unsuitable for industries with high air cleanliness requirements. Furthermore, although oil injection helps with lubrication and cooling, it increases the requirements for lubricant quality and replacement frequency, and necessitates regular cleaning or replacement of filters and separators, thus increasing compressor maintenance costs.

[0005] In addition, there are existing technologies such as those with the announcement number " The Chinese invention patent for a water-lubricated single-screw compressor discloses a method that uses water instead of oil as the compression, sealing, and cooling medium. Combined with sealing and isolation technology, this ensures the cleanliness of the compressed air, providing completely oil-free compressed air. This is suitable for industries or fields with high compressed air quality requirements, such as environmental protection, electronics, medical and health, and food. However, this solution still requires additional water-air separation treatment of the compressed air, which is complex and costly. The water-lubricated equipment structure is relatively complex, and it uses a lot of special materials (such as stainless steel screws and volutes), leading to excessively high production costs. Furthermore, because the cooling medium path in the existing technology is within the volute and the compression chamber formed between the star wheel assembly and the screw, it requires high-quality water, necessitating the use of softened or deionized water. Otherwise, scaling and blockage of the water channels can easily occur, leading to cooling failure and component damage.

[0006] The public account is " A Chinese invention patent discloses an oil-free single-screw compressor that uses self-lubricating metal materials to manufacture the screw and star wheel assembly, enabling it to operate entirely without oil or water. The compressed air is purer and the purification process is simplified. However, because this solution does not use lubricating oil or water during compression, it lacks the cooling and sealing effects of oil, resulting in a more significant temperature rise in the compression chamber and higher requirements for the cooling system. Furthermore, this solution does not provide a perfect cooling solution adapted to this type of oil-free and water-free dry compressor and requires further improvement. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to provide a compressor cooling structure in which the cooling medium and the compressed gas do not directly contact each other, thereby improving the purity of the compressed air. The further technical problem to be solved is to provide a compressor cooling structure that is simpler in structure, lower in cost, and more universal.

[0008] This invention provides the following technical solution:

[0009] A cooling structure for a screw compressor includes a volute, a screw assembly, and a star wheel assembly. The screw assembly and the star wheel assembly are assembled inside the volute. The screw assembly includes a screw shaft coaxially arranged and a screw fixedly connected to the screw shaft. The screw has a hollow interior forming an inner cooling cavity. The screw assembly also has an inlet channel and an outlet channel. The inner cooling cavity has a closed structure. The two ends of the inlet channel are connected to the inside and outside of the inner cooling cavity, respectively. The two ends of the outlet channel are also connected to the inside and outside of the inner cooling cavity, respectively.

[0010] In this design, the cooling medium enters the inner cooling chamber through the inlet channel. The high-speed rotating screw assembly causes the newly entering cooling medium to be thrown against the inner wall of the inner cooling chamber by centrifugal force, thus cooling the inner cooling chamber. Simultaneously, the cooling medium, after absorbing heat, flows out through the outlet channel, realizing the circulation of the cooling system. This design further improves upon existing components without requiring additional parts, resulting in a simple structure. Furthermore, this design is applicable to both traditional oil- or water-lubricated compressors and dry-type oil-free and water-free compressors. The inlet and outlet channels are independent, working in conjunction with the inner cooling chamber to achieve internal cooling of the screw. The cooling medium does not directly contact the compressor's compression chamber, eliminating the need for oil or water lubrication. This ensures that the compressed air is oil-free and water-free, meeting the high cleanliness requirements of industries such as electronics, pharmaceuticals, food, and environmental protection. It also eliminates subsequent processes such as oil removal and water-gas separation, simplifying the compressed air purification process and reducing purification costs. In this design, the cooling medium can be a liquid medium, such as water or oil, or a gaseous medium, such as atomized gas. It is also suitable for air cooling, making it more versatile.

[0011] In the cooling structure of this screw compressor, the inner cooling chamber is designed with an expanded diameter, and the inner diameter of the inner cooling chamber gradually increases from the corresponding screw inlet end to the outlet end.

[0012] This design expands the diameter of the internal cooling chamber from the low-pressure zone to the high-pressure zone, resulting in a longer perimeter in the high-pressure zone and a larger contact area with the cooling medium. This allows for more thorough heat exchange between the high-pressure zone and the cooling medium, thus improving the cooling effect.

[0013] In the cooling structure of this screw compressor, the screw shaft extends into and passes through the inner cooling cavity. The inlet channel and the outlet channel are hollow channels axially arranged inside the screw shaft. The second inlet of the inlet channel extends into the inner cooling cavity and is close to the end with the smaller inner diameter of the inner cooling cavity. The first outlet of the outlet channel extends into the inner cooling cavity and is close to the end with the larger inner diameter of the inner cooling cavity.

[0014] The screw shaft has a first inlet and a second inlet in the inlet channel, which connect to the outside and inside of the inner cooling chamber, respectively. Similarly, the outlet channel has a first outlet and a second outlet, which also connect to the inside and outside of the inner cooling chamber, respectively. The cooling medium enters the inlet channel through the first inlet and flows into the inner cooling chamber inside the screw through the second inlet. After absorbing heat, the cooling medium flows into the outlet channel through the first outlet and then out through the second outlet, thus circulating the cooling system. By setting the inlet and outlet channels of the cooling medium on the screw shaft, further improvements are made to the existing components without requiring additional parts, resulting in a simple structure and easier layout of the cooling medium circulation path. Furthermore, the second inlet of the inlet channel corresponds to the smaller end of the inner diameter of the inner cooling chamber, and the first outlet of the outlet channel corresponds to the larger end of the inner diameter of the inner cooling chamber. This matches the flow path of the cooling medium with the volume change of the screw compression chamber, resulting in more thorough cooling at the outlet end where gas compression generates more heat, thus improving the overall targeting and efficiency of the cooling system.

[0015] In the cooling structure of this screw compressor, the inner wall of the inner cooling chamber is provided with an internal flow guiding structure.

[0016] This solution guides the cooling medium through an internal flow-guiding structure. For example, internal flow-guiding grooves are set on the inner wall of the inner cooling cavity, and inner protrusions are formed between adjacent internal flow-guiding grooves. The inner protrusions can also stir and disperse the cooling medium. The combination of the two makes the cooling medium more evenly dispersed in the inner cooling cavity, and the heat transfer is more complete and uniform. When air cooling is used, the internal flow-guiding structure consists of several heat sinks set on the inner wall of the inner cooling cavity, which further improves the cooling effect on the screw when using air cooling.

[0017] The internal flow guiding structure has several internal flow guiding grooves on the inner wall of the internal cooling cavity. A raised inner convex part is formed between adjacent internal flow guiding grooves. The internal flow guiding grooves of the flow guiding structure are spiral-shaped. The position of the internal flow guiding grooves corresponds one-to-one with the position of the screw teeth on the outside of the screw, and the position of the inner convex part corresponds one-to-one with the position of the outer spiral groove on the outside of the screw.

[0018] In this design, when the guiding structure adopts a spiral-shaped inner guiding groove, the corresponding structural arrangement makes the cavity wall thickness of the screw tooth area and the outer spiral groove area more uniform. This effectively solves the problems of uneven wall thickness and severe local heat accumulation in traditional screw cooling cavities, eliminates the risk of local overheating of the screw, balances the overall temperature field of the screw, and significantly improves the structural stability and service life of the screw during high-speed operation. On the other hand, when the screw assembly rotates at high speed with the equipment, the protruding inner part of the inner wall of the inner cooling cavity can continuously stir, disperse, and disturb the cooling medium in the cavity. Combined with the directional guiding effect of the spiral inner guiding groove, it can effectively break the static layer and laminar flow state of the cooling medium, so that the cooling medium is evenly dispersed and fully adheres to the entire inner wall surface of the inner cooling cavity, avoiding heat exchange dead zones, significantly improving the heat exchange efficiency and heat dissipation uniformity between the cooling medium and the screw substrate, ensuring continuous and stable heat dissipation in the high-temperature area of ​​screw compression, and effectively improving the overall cooling performance and compression efficiency.

[0019] In the cooling structure of this screw compressor, one end of the inner cooling chamber is inside the screw, and the other end is open and communicates with the outside. A sealing plate is provided at the opening of the inner cooling chamber. The sealing plate is fixedly connected to the screw and seals the opening of the inner cooling chamber.

[0020] This solution provides a specific internal cooling cavity structure and its sealing structure, which is more conducive to the integral forging of the screw, and the sealing plate can effectively seal the open internal cooling cavity.

[0021] In the cooling structure of this screw compressor, an external cooling cavity is provided on the outer periphery of the part of the volute that encloses the screw, and the external cooling cavity is provided with an external inlet and an external outlet.

[0022] In this design, to adapt to the high-pressure and high-temperature operating conditions of a single-screw compressor, directional and precise cooling is achieved in the core area of ​​the screw compressor. External cooling chambers are provided on the upper and lower outer peripheries of the volute, with their locations corresponding one-to-one with the compression chambers. These chambers are specifically designed for precise cooling of the compression chamber portion of the volute. Each external cooling chamber has an external inlet and an external outlet. The cooling medium enters the external cooling chamber through the external inlet, exchanges heat with the compression chamber wall of the volute, and then exits through the external outlet. The external cooling chambers are integrally formed into the volute and are sealed by cooling chamber covers.

[0023] In the cooling structure of this screw compressor, the star wheel assembly includes a star wheel and a star wheel shaft. One end of the star wheel is the compression end and the other end is the assembly end. The star wheel shaft is located at the assembly end and is fixedly connected to the assembly end. A star wheel support block is formed in the volute corresponding to the compression end position. The star wheel support block contacts the compression end of the star wheel, and the external cooling cavity extends into the interior of the star wheel support block.

[0024] This solution improves the structure of the star wheel assembly, eliminating the traditional double-sided shafts and providing single-shaft support on one side of the star wheel. The star wheel bearing block, integrally formed with the volute housing, abuts against and seals the compression end of the star wheel. During assembly, the star wheel assembly is directly installed from the star wheel assembly port on one side of the housing, eliminating the need for vertical alignment assembly like traditional screw compressors. This reduces the number of parts and simplifies the assembly path of the star wheel assembly. Furthermore, the structural cooperation between the external cooling cavity and the star wheel bearing block further expands the cooling area of ​​the external cooling cavity, allowing it to simultaneously cover both the volute housing and the star wheel bearing block, further cooling the high-temperature area at the star wheel.

[0025] A cooling method for a screw compressor includes an independent but coordinated internal cooling cycle and an external cooling cycle. The cooling medium flows in a closed loop throughout the process and does not come into contact with the medium inside the compression chamber. The internal cooling cycle is as follows: the cooling medium is sent into the internal cooling chamber near the screw inlet end through the inlet channel. When the screw assembly rotates, the cooling medium flows along the inner wall of the internal cooling chamber under the action of centrifugal force. The structure of the internal cooling chamber, which gradually expands from the inlet end to the outlet end, matches the heat distribution of the screw compression. The cooling medium is guided and disturbed by the protrusions in the spiral inner guide groove, so that the cooling medium and the inner wall of the screw can exchange heat fully. The cooled medium after heat exchange is collected at the outlet end of the internal cooling chamber and discharged and recycled through the outlet channel.

[0026] In the internal cooling cycle, the flow direction of the cooling medium is consistent with the compression direction of the screw, and the cooling medium gradually absorbs heat as it flows through the internal cooling chamber.

[0027] Compared with the prior art, the technical effects of the present invention are as follows:

[0028] I. This invention integrates an internal cooling chamber inside the screw and sets independent inlet and outlet channels inside the screw shaft. It only optimizes the structure of the original core components without adding any additional main components. The overall structure is simple and easy to assemble. This cooling structure has strong adaptability and is compatible with oil-filled compressors and dry compressors. It can also be matched with various types of cooling media and can be flexibly adapted and adjusted according to actual working conditions, which significantly improves the universality of the equipment.

[0029] Second, the invention adopts a closed-loop cooling mode, in which the cooling medium does not directly contact the medium inside the compression chamber throughout the process, which greatly reduces the requirements for cooling water quality and eliminates the need for softened water or deionized water treatment equipment. This avoids problems such as scaling, blockage, and corrosion in the cooling water channels from the source, effectively reducing the cost of later use and maintenance of the equipment. At the same time, the structure does not require the extensive use of special high-temperature and corrosion-resistant materials such as stainless steel, which significantly reduces the equipment manufacturing cost and results in outstanding economic benefits.

[0030] Third, the internal cooling chamber of this invention adopts a gradually expanding diameter structure from the inlet end to the outlet end, which precisely matches the volume change law of the screw compression chamber from low pressure to high compression capacity. It specifically enhances the heat exchange area and cooling force of the high pressure and high temperature area at the outlet end of the compressor, realizes precise zoned cooling, and greatly improves the cooling targeting and overall heat exchange efficiency. At the same time, the internal guide groove or heat sink structure can be flexibly selected according to the type of cooling medium to adapt to different cooling conditions and further enhance the heat dissipation effect.

[0031] Fourth, this invention innovatively adopts a dual cooling system that combines internal screw cooling and external volute cooling. The internal and external cooling cycles operate independently and work together to remove a large amount of heat generated during the compressor's compression process in an all-round and efficient manner, quickly balance the temperature field of the whole machine, ensure the compressor's continuous and stable thermal balance, and avoid performance degradation caused by high temperature overheating.

[0032] Fifth, this invention optimizes the star wheel assembly and volute housing adaptation structure, simplifies the star wheel assembly structure, and utilizes the integrated extension structure of the volute housing star wheel support block and the external cooling cavity to effectively expand the cooling coverage area of ​​the external cooling cavity, realize directional auxiliary cooling of the high-frequency and high-temperature area of ​​the star wheel compression end, solve the problem of local overheating of the star wheel, and further improve the whole machine's overall cooling system.

[0033] VI. This invention features a proprietary internal and external synergistic cooling process. By differentiating the placement of the medium inlet and outlet positions and relying on the centrifugal force of the screw rotation to achieve dynamic heat exchange, and by extending the flow channel to prolong the external heat exchange time, compared with the traditional static cooling method, it can achieve orderly, sufficient, and continuous heat exchange of the cooling medium, avoid heat exchange dead zones and medium waste, maximize the heat dissipation advantages of the internal and external dual cooling structure, stably improve the cooling uniformity and cooling efficiency of the whole machine, and ensure the long-term efficient, low-failure, and stable operation of the compressor. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the overall structure of the screw compressor of the present invention.

[0036] Figure 2 This is a schematic cross-sectional view of the screw compressor of the present invention.

[0037] Figure 3 This is a schematic diagram of the overall structure of the cooling structure of the screw compressor of the present invention.

[0038] Figure 4 This is a cross-sectional view of the cooling structure of the screw compressor of the present invention.

[0039] Figure 5 This is a cross-sectional view of the cylindrical screw assembly of the cooling structure of the screw compressor of the present invention.

[0040] Figure 6 This is a cross-sectional view of the irregularly shaped screw assembly of the cooling structure of the screw compressor of the present invention.

[0041] Figure 7 This is a schematic diagram of the sealing plate structure of the cooling structure of the screw compressor of the present invention.

[0042] Figure 8 This is an enlarged view of point A of the cooling structure of the screw compressor of the present invention.

[0043] Figure 9 This is an enlarged view of section B of the cooling structure of the screw compressor of the present invention.

[0044] Figure 10 This is a schematic diagram of the internal structure of the volute of the cooling structure of the screw compressor of the present invention.

[0045] Figure 11 This is a schematic diagram of the external cooling cavity structure of the screw compressor of the present invention.

[0046] Figure 12 This is a schematic diagram of the internal structure of the screw in the cooling structure of the screw compressor of the present invention.

[0047] Figure 13 This is a schematic diagram of the volute structure with star wheel bearing block in the cooling structure of the screw compressor of the present invention.

[0048] Figure 14 This is a schematic diagram of a single-sided axial star wheel assembly structure of the cooling structure of the screw compressor of the present invention.

[0049] In the diagram, 1. Volute; 10. Outer shell; 11. Star wheel bearing block; 2. Screw assembly; 21. Screw shaft; 22. Screw; 23. Outer spiral groove; 24. Screw teeth; 25. Inner cooling cavity; 251. Inner guide groove; 252. Inner protrusion; 253. First step; 254. Second step; 26. Sealing plate; 261. Shaft hole; 262. First flange; 263. First sealing groove; 264. First sealing ring; 265. Second flange; 266. Second sealing groove ; 267, Second sealing ring; 268, Third sealing groove; 269, Third sealing ring; 27, External cooling chamber; 271, External inlet; 272, External outlet; 273, Baffle; 3, Star wheel assembly; 31, Star wheel; 311, Compression end; 312, Assembly end; 32, Star wheel shaft; 33, Bearing; 34, Bearing sleeve; 4, Inlet channel; 41, First inlet; 42, Second inlet; 5, Outlet channel; 51, First outlet; 52, Second outlet. Detailed Implementation

[0050] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0051] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0053] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0054] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0055] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0056] In this implementation plan: such as Figures 1-4 As shown, a cooling structure for a screw compressor includes a volute 1, a screw assembly 2, and a star wheel assembly 3. The screw assembly 2 is coaxially assembled within the accommodating cavity of the volute 1. The star wheel assembly 3 meshes with the screw 22 of the screw assembly 2. The volute 1, along with the meshed screw assembly 2 and star wheel assembly 3, is integrally assembled inside the volute 1, forming the core compression and cooling unit of the compressor. The screw assembly 2 includes a screw shaft 21 and a screw 22 coaxially fixed together. The screw shaft 21 can be fixed to the screw 22 through conventional mechanical connection methods such as key connection or interference fit to ensure synchronous rotation of the two.

[0057] Furthermore, such as Figures 1-5 As shown, a hollow inner cooling cavity 25 is formed inside the screw 22. One end of the screw shaft 21 extends axially into the inner cooling cavity 25. The screw shaft 21 has independent inlet channels 4 and outlet channels 5 along its own axial direction. The inlet channels 4 have a first inlet 41 and a second inlet 42 at their two ends. The first inlet 41 connects to the cooling medium supply end outside the inner cooling cavity 25, and the second inlet 42 extends into the inner cooling cavity 25, thus connecting the inlet channels 4 and the inner cooling cavity 25. The outlet channels 5 have a first outlet 51 and a second outlet 52 at their two ends. The first outlet 51 extends into the inner cooling cavity 25, and the second outlet 52 connects to the cooling medium recovery end outside the inner cooling cavity 25, thus circulating the cooling medium. Figure 5 The middle section is a standard cylindrical screw assembly. Figure 6 The middle part is an irregularly shaped screw assembly. The cooling structure of this solution only improves the original parts of the screw assembly 2 without adding new parts. This solution can be applied to screw assemblies 2 of various conventional and unconventional shapes.

[0058] In this embodiment, the circulation path of the cooling medium is as follows: the cooling medium from the external cooling medium supply end enters the inlet channel 4 through the first inlet 41, flows into the inner cooling chamber 25 through the second inlet 42, and when the screw assembly 2 rotates at high speed, the cooling medium is thrown towards the inner wall of the inner cooling chamber 25 by centrifugal force, fully contacts the inner wall of the screw 22 and completes heat exchange. After absorbing heat, the cooling medium enters the outlet channel 5 through the first outlet 51 and is finally discharged to the external recovery end through the second outlet 52, thus realizing the internal cooling of the screw 22. Under this cooling method, the cooling medium does not directly contact the compression chamber, and there is no need for oil or water lubrication medium, which can ensure that the compressed air is oil-free and water-free. Moreover, only the original screw assembly 2 needs to be structurally improved, and no additional cooling components are required, so the overall structure is simple.

[0059] Furthermore, the inner cooling cavity 25 adopts an expanded diameter setting, with its inner diameter gradually increasing from the air inlet end of the corresponding screw 22 to the air outlet end. This adapts to the volume change characteristics of the outer spiral groove 23 of the screw 22 from the air inlet end (low-pressure area) to the air outlet end (high-pressure area), making the inner wall circumference of the inner cooling cavity 25 in the high-pressure heating area longer and the contact area between the cooling medium and the screw 22 larger, thereby achieving sufficient heat exchange in the high-pressure area and improving the targeting of cooling.

[0060] Preferred, such as Figure 12 As shown, the inner wall of the inner cooling cavity 25 is provided with several inner guide grooves 251, and a raised inner protrusion 252 is formed between adjacent inner guide grooves 251. The shape and layout of the inner guide grooves 251 can be arranged according to actual needs, such as strip shape, spiral shape, etc. Preferably, the inner guide grooves 251 are spiral-shaped, and the inner guide grooves 251 correspond one-to-one with the positions of the screw teeth 24 on the outside of the screw 22. The inner protrusions 252 correspond one-to-one with the positions of the outer spiral grooves 23 on the outside of the screw 22. This structural design makes the wall thickness of each part of the screw 22 more uniform, avoiding the problem of local overheating caused by uneven wall thickness, and ensuring uniform heat dissipation of the screw 22. At the same time, when the screw assembly 2 rotates, the inner protrusions 252 can stir and disperse the cooling medium in the cavity, so that the cooling medium is evenly dispersed on the inner wall of the inner cooling cavity 25, further improving the sufficiency and uniformity of heat transfer.

[0061] Preferably, the inner wall of the inner cooling cavity 25 is provided with a number of heat sinks (not shown in the figure). The heat sinks are the finned heat sinks commonly used for air cooling on the market. Those skilled in the art can arrange the specific layout and number of heat sinks according to actual needs, which will not be elaborated here.

[0062] In this embodiment, after the second inlet 42 of the inlet channel 4 extends into the inner cooling cavity 25, its port is close to the end with the smaller inner diameter of the inner cooling cavity 25 (i.e., the air inlet end of the screw 22); after the first outlet 51 of the outlet channel 5 extends into the inner cooling cavity 25, its port is close to the end with the larger inner diameter of the inner cooling cavity 25 (i.e., the air outlet end of the screw 22). This design makes the flow direction of the cooling medium consistent with the compression direction of the screw 22. The cooling medium gradually absorbs heat as it flows through the inner cooling cavity 25, forming a longer heat exchange at the air outlet end where the heat generation is more obvious, further improving the overall cooling efficiency.

[0063] To ensure the sealing performance of the inner cooling cavity 25 and prevent leakage of the cooling medium, such as Figures 6-9 As shown, one end of the inner cooling cavity 25 is located inside the screw 22, and the other end is open at the end of the screw and communicates with the outside. A sealing plate 26 is fixedly installed at the opening of the inner cooling cavity 25. The sealing plate 26 can be fixed to the end face of the screw 22 by means of bolts or other methods to achieve a seal at the opening of the inner cooling cavity 25. This invention uses a three-stage water sealing structure to achieve an all-round seal of the inner cooling cavity 25, and the specific structure is as follows:

[0064] 1. The center of the sealing plate 26 is provided with a shaft hole 261 through which the screw shaft 21 passes. An annular first flange 262 is integrally formed on the outer side of the shaft hole 261. The first flange 262 cooperates with the outer peripheral wall of the screw shaft 21, forming an annular first sealing groove 263 between the first flange 262 and the shaft hole 261. A first sealing ring 264 is engaged in the first sealing groove 263 to seal the gap between the screw shaft 21 and the shaft hole 261.

[0065] 2. The opening end of the inner cooling cavity 25 is machined with equal diameter to form a stepped first step 253. The sealing plate 26 is integrally formed with an annular second flange 265 on the side facing the inner cooling cavity 25. The outer diameter of the second flange 265 is slightly smaller than the inner diameter of the first step 253. An annular second sealing groove 266 is opened on the outer peripheral wall of the second flange 265. A second sealing ring 267 is engaged in the second sealing groove 266 to seal the gap between the sealing plate 26 and the opening end of the inner cooling cavity 25.

[0066] 3. The closed end of the inner cooling cavity 25 is also machined with a constant diameter to form a stepped second step 254. The second step 254 mates with the outer peripheral wall of the screw shaft 21 to form an annular third sealing groove 268. A third sealing ring 269 is engaged within the third sealing groove 268 to seal the gap between the screw shaft 21 and the closed end of the inner cooling cavity 25. In this embodiment, the first, second, and third sealing rings can all be made of elastic sealing materials such as rubber or polytetrafluoroethylene. The three-stage water sealing structure works together to achieve efficient sealing of the inner cooling cavity 25, completely preventing cooling medium leakage and ensuring the operational stability of the cooling structure.

[0067] Furthermore, such as Figure 11 As shown, to achieve all-round cooling of the compressor, an external cooling cavity 27 is integrally formed on the outer circumference of the part of the volute 1 that encloses the screw 22. In this embodiment, the upper and lower outer circumferences of the volute are provided with external cooling cavities 27 corresponding to the compression cavity positions of the screw 22. The arrangement of the external cooling cavities 27 corresponds one-to-one with the compression cavities, realizing directional and precise cooling of the core area of ​​the screw compression. Each external cooling cavity 27 is independently provided with an external inlet 271 and an external outlet 272. The opening of the external cooling cavity 27 is sealed by a cooling cavity cover. A sealing gasket can be added between the cooling cavity cover and the volute 1 to improve the sealing performance. The external cooling medium enters the external cooling cavity 27 through the external inlet 271, completes heat exchange with the compression cavity wall of the volute 1, and is discharged through the external outlet 272.

[0068] Furthermore, several baffles 273 are fixed inside the external cooling chamber 27. One end of each baffle 273 is sealed to the inner wall of the external cooling chamber 27, while the other end has a gap between it and the opposite inner wall of the external cooling chamber 27 for the cooling medium to pass through. The baffles 273 are staggered along the length of the external cooling chamber 27, forming a continuous "S"-shaped cooling medium flow channel inside the external cooling chamber 27. This structure can significantly extend the flow path and heat exchange time of the cooling medium in the external cooling chamber 27, improving the heat exchange efficiency between the cooling medium and the compression chamber wall of the volute 1. The cooling medium circulation systems of the internal cooling chamber 25 and the external cooling chamber 27 operate independently but work synergistically. The internal cooling structure directly cools the screw 22, while the external cooling precisely cools the compression chamber of the volute 1. Together, they achieve all-round, high-efficiency cooling of the compressor's core components. Moreover, the cooling medium does not come into contact with the compression chamber throughout the process, has no special requirements for water quality, and does not require the use of softened or deionized water, avoiding the problem of scale buildup and blockage in the water channels, and reducing the operating and maintenance costs of the equipment.

[0069] In this embodiment, the number of baffles 273 in the external cooling cavity 27 can be flexibly set according to the length of the volute 1 and the cooling requirements. The baffles 273 are made of metal plates to ensure structural strength. The one-piece molding design of the external cooling cavity 27 does not require the addition of extra parts to the volute 1, which simplifies the processing technology of the volute 1 and reduces production costs.

[0070] Furthermore, such as Figure 13 , Figure 14As shown, the star wheel assembly 3 includes a star wheel 31 and a star wheel shaft 32. One end of the star wheel 31 is a compression end 311, and the other end is an assembly end 312. Only the assembly end 312 is fixedly connected to the star wheel shaft 32. The star wheel assembly 3 is assembled in the volute 1 through a bearing 33 and a bearing sleeve 34. The upper half of the volute 1 extends to the left to form a star wheel support block 11, and the lower half of the volute 1 extends to the right to form a star wheel support block 11. The two star wheel support blocks 11 extend above or below the star wheel 31 and contact the compression end 311 of the star wheel 31. The upper and lower external cooling cavities 27 extend into the interior of the two star wheel support blocks 11. Through the structural cooperation between the external cooling cavity 27 and the star wheel support block 11, the cooling area of ​​the external cooling cavity 27 is further expanded, so that the external cooling cavity 27 can simultaneously cover the main body of the volute 1 and the star wheel support block 11, further cooling the high temperature area at the star wheel 31.

[0071] Based on the above cooling structure, this embodiment also discloses a cooling method for a screw compressor. It employs a dual-cycle, closed-loop cooling system where the internal and external cooling elements operate independently yet collaboratively. The cooling medium does not contact the compression chamber medium throughout the entire cooling cycle. In the internal cooling cycle, the cooling medium is fed into the inner cooling chamber 25 near the intake end of the screw 22 through the inlet channel 4. When the screw assembly 2 rotates at high speed, centrifugal force causes the cooling medium to flow against the gradually expanding inner wall of the inner cooling chamber 25. Combined with the guiding and agitating effects of the spiral inner guide groove 251 and the inner protrusion 252, this adapts to the gradient heating characteristics of the screw 22 during compression, thereby achieving optimal cooling performance for the screw compressor. The inner wall of the compressor is uniformly and fully heat-exchanged. The heat-exchanged medium gathers at the outlet end and is discharged and recycled through the outlet channel 5. In the external cooling cycle, the cooling medium enters the external cooling chamber 27 through the external inlet 271 and flows slowly along the S-shaped flow channel formed by the baffle 273, extending the heat exchange stroke to continuously cool the compression chamber wall of the volute 1. At the same time, the external cooling chamber 27, which extends into the star wheel bearing block 11, assists in heat dissipation of the high-temperature area of ​​the compression end 311 of the star wheel 31. Finally, the heat exchange medium is discharged from the external outlet 272. Through the coordinated operation of the internal and external dual circulation, the compressor core compression area is cooled in a full range, with high efficiency and uniformity.

[0072] The same or similar parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments.

[0073] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A cooling structure for a screw compressor, comprising a volute (1), a screw assembly (2), and a star wheel assembly (3), wherein the screw assembly (2) and the star wheel assembly (3) are assembled within the volute (1), and the screw assembly (2) comprises a screw shaft (21) coaxially arranged and a screw (22) fixedly connected to the screw shaft (21), characterized in that: The screw (22) has a hollow interior forming an inner cooling cavity (25). The screw assembly (2) is also provided with an inlet channel (4) and an outlet channel (5). The inner cooling cavity (25) has a closed structure at both ends. The inlet channel (4) connects the inside and outside of the inner cooling cavity (25) at both ends, and the outlet channel (5) connects the inside and outside of the inner cooling cavity (25) at both ends.

2. The cooling structure of a screw compressor according to claim 1, characterized in that: The inner cooling cavity (25) is designed with an enlarged diameter, and the inner diameter of the inner cooling cavity (25) gradually increases from the air inlet end of the corresponding screw (22) to the air outlet end.

3. The cooling structure of a screw compressor according to claim 2, characterized in that: The screw shaft (21) extends into and passes through the inner cooling cavity (25). The inlet channel (4) and the outlet channel (5) are hollow channels axially arranged inside the screw shaft (21). The second inlet (42) of the inlet channel (4) extends into the inner cooling cavity (25) and is close to the smaller end of the inner diameter of the inner cooling cavity (25). The first outlet (51) of the outlet channel (5) extends into the inner cooling cavity (25) and is close to the larger end of the inner diameter of the inner cooling cavity (25).

4. Cooling structure of a screw compressor according to claim 1 or 2, characterized in that The inner wall of the inner cooling cavity (25) is provided with an internal flow guiding structure.

5. A cooling structure of a screw compressor according to claim 4, characterized in that: The inner wall of the inner cooling cavity (25) is provided with a number of inner guide grooves (251), and a raised inner protrusion (252) is formed between adjacent inner guide grooves (251). The inner guide grooves (251) of the guide structure are spiral-shaped. The inner guide grooves (251) correspond one-to-one with the screw teeth (24) outside the screw (22), and the inner protrusions (252) correspond one-to-one with the outer spiral grooves (23) outside the screw (22).

6. Cooling structure of a screw compressor according to claim 1 or 2, characterized in that One end of the inner cooling cavity (25) is inside the screw (22), and the other end is open and communicates with the outside. A sealing plate (26) is provided at the opening of the inner cooling cavity (25). The sealing plate (26) is fixedly connected to the screw (22) and seals the opening of the inner cooling cavity (25).

7. Cooling structure of a screw compressor according to claim 1 or 2, characterized in that The outer periphery of the part of the volute (1) that encloses the screw (22) is provided with an outer cooling cavity (27), and the outer cooling cavity (27) is provided with an outer inlet (271) and an outer outlet (272).

8. Cooling structure of a screw compressor according to claim 7, characterized in that The star wheel assembly (3) includes a star wheel (31) and a star wheel shaft (32). One end of the star wheel (31) is a compression end (311) and the other end is an assembly end (312). The star wheel shaft (32) is located at the assembly end (312) and is fixedly connected to the assembly end (312). The volute (1) has a star wheel support block (11) formed at the position corresponding to the compression end (311). The star wheel support block (11) is in contact with the compression end (311) of the star wheel (31), and the external cooling cavity (27) extends into the interior of the star wheel support block (11).

9. A cooling method for a screw compressor, applied to the cooling structure of a screw compressor according to any one of claims 1-8, characterized in that: It includes independent internal and external cooling cycles, with the cooling medium flowing in a closed loop throughout and not coming into contact with the medium inside the compression chamber.

10. A cooling method for a screw compressor according to claim 9, characterized in that: The internal cooling cycle process is as follows: the cooling medium is sent into the inner cooling cavity (25) near the air inlet end of the screw (22) through the inlet channel (4). When the screw assembly (2) rotates, the cooling medium adheres to the inner wall of the inner cooling cavity (25) under the action of centrifugal force. The structure of the inner cooling cavity (25) gradually expands from the air inlet end to the air outlet end to match the screw compression heat distribution. The cooling medium is guided and disturbed by the spiral inner guide groove (251) and the inner protrusion (252) so that the cooling medium and the inner wall of the screw (22) can exchange heat fully. The cooled medium after heat exchange gathers at the air outlet end of the inner cooling cavity (25) and is discharged and recycled through the outlet channel (5) in sequence. In the internal cooling cycle, the flow direction of the cooling medium is consistent with the compression direction of the screw (22). The cooling medium gradually absorbs heat in the process of flowing through the inner cooling cavity (25).

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