Oil-free screw compressor and water chiller

Abstract

This utility model discloses an oil-free screw compressor and chiller unit, including a housing with a second rotor; the housing has a first assembly cavity and a second assembly cavity arranged sequentially outward on both sides corresponding to the working section of the second rotor, and the first assembly cavity and the second assembly cavity are adjacent and communicate with each other; a second sealing element arranged around the outer periphery of the second rotor is matched and installed in the first assembly cavity, and a second bearing arranged around the outer periphery of the second rotor is matched and installed in the second assembly cavity. By arranging the first assembly cavity and the second assembly cavity adjacent and communicating, the structure of the first assembly cavity and the second assembly cavity is made more compact, thereby shortening the bearing span between the second bearings, thus improving the stiffness of the second rotor, increasing the critical speed of the second rotor, and reducing the vibration amplitude of the second rotor.

Description

Technical Field

[0001] This utility model relates to the field of liquid variable displacement mechanical technology, and in particular to an oil-free screw compressor and chiller unit. Background Technology

[0002] Oil-free screw compressors are gas compression devices that do not require lubricating oil during the compression process. Their primary purpose is to become the preferred choice in high-end manufacturing, medical, and food industries due to their advantages such as being oil-free, highly efficient, and having a long lifespan. However, despite these advantages, oil-free screw compressors also have some drawbacks and limitations in practical applications.

[0003] In oil-free screw compressors, mechanical seals are a common sealing design used to prevent gas leakage and ensure the airtightness of the equipment during operation. For example... Figure 1 As shown, a first bearing 200 and a first seal 300 are independently installed at both ends of the first rotor 100, and the first bearing 200 is assembled on the outside of the first seal 300, resulting in a long bearing span between the first bearings 200, which in turn results in low stiffness of the first rotor 100. Utility Model Content

[0004] This invention provides an oil-free screw compressor and chiller unit to solve the problem that the bearing span of existing oil-free screw compressors is long, resulting in low rotor stiffness.

[0005] The technical solution of this utility model is an oil-free screw compressor, including a housing with a second rotor; the housing has a first assembly cavity and a second assembly cavity arranged outwardly on both sides corresponding to the working section of the second rotor, and the first assembly cavity and the second assembly cavity are arranged adjacent to each other and communicate with each other;

[0006] The first assembly cavity is fitted with a second seal that surrounds the outer periphery of the second rotor, and the second assembly cavity is fitted with a second bearing that surrounds the outer periphery of the second rotor.

[0007] Furthermore, the second rotor has a through-hole along the axial direction in the middle part, and the through-hole is used to deliver lubricating oil;

[0008] The through oil hole communicates with the first assembly cavity and / or the second assembly cavity.

[0009] Furthermore, the second seal includes a dynamic ring and a stationary ring;

[0010] The first assembly cavity is fitted with a stationary ring;

[0011] Both sides of the working section of the second rotor are provided with recessed grooves facing inward to the first assembly cavity. A rotating ring is installed in the recessed groove, and the end faces of the rotating ring and the stationary ring are in direct contact to form a dynamic sealing interface.

[0012] Furthermore, the stationary ring and the second bearing are in contact, or the distance between the stationary ring and the second bearing is no greater than 1 mm.

[0013] Furthermore, the bearing span L between the second bearings on both sides of the working section of the second rotor is ≤1.2a;

[0014] Where a is the length of the working section of the second rotor.

[0015] Furthermore, the stationary ring is fixed in the first assembly cavity by a fastener, and a gap is formed between the stationary ring and the first assembly cavity in both the radial and / or axial directions.

[0016] Furthermore, the depth of the settling groove is greater than the thickness of the moving ring, so that the settling groove forms an axial compensation space.

[0017] Furthermore, an elastic sealing ring is provided between the bottom of the settling tank and the end face of the moving ring.

[0018] Furthermore, the moving ring is made of a hard material, and the stationary ring is made of a soft material.

[0019] This utility model also proposes a water chiller unit, which includes the oil-free screw compressor described above.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] This invention uses an adjacent and interconnected first and second assembly cavities to make the structure of the first and second assembly cavities more compact, thereby shortening the bearing span between the second bearings, thus improving the stiffness of the second rotor, increasing the critical speed of the second rotor, and reducing the vibration amplitude of the second rotor. Attached Figure Description

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this invention are used to distinguish different objects and not to describe a particular order.

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a partial cross-sectional view of an existing oil-free screw compressor in the background art;

[0025] Figure 2 This is a partial cross-sectional view of the first oil-free screw compressor proposed in this utility model;

[0026] Figure 3 This invention provides a partial schematic diagram of the groove on the second rotor and the first assembly cavity.

[0027] Figure 4 This is a partial cross-sectional view of the second type of oil-free screw compressor proposed in this utility model;

[0028] Figure 5 for Figure 4 An enlarged schematic diagram of reference numeral A in the attached figure;

[0029] Figure 6 This is a partial cross-sectional view of the third type of oil-free screw compressor proposed in this utility model.

[0030] Figure label:

[0031] 10. Shell;

[0032] 101. First assembly cavity; 102. Second assembly cavity;

[0033] 20. Second rotor;

[0034] 201. Working section; 202. Through oil hole; 203. Settlement tank; 204. Oil supply through hole;

[0035] 30. Second sealing element;

[0036] 301. Moving ring; 302. Stationary ring;

[0037] 40. Second bearing;

[0038] 50. Elastic sealing ring;

[0039] 100. First rotor;

[0040] 200. First bearing;

[0041] 300. First sealing element. Detailed Implementation

[0042] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the present utility model, and does not imply that every embodiment of the present utility model must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0043] The principle and structure of this utility model will be described in detail below with reference to the accompanying drawings and embodiments.

[0044] Oil-free screw compressors are gas compression devices that do not require lubricating oil during the compression process. Their primary purpose is to become the preferred choice in high-end manufacturing, medical, and food industries due to their advantages such as being oil-free, highly efficient, and having a long lifespan. However, despite these advantages, oil-free screw compressors also have some drawbacks and limitations in practical applications.

[0045] In oil-free screw compressors, mechanical seals are a common sealing design used to prevent gas leakage and ensure the airtightness of the equipment during operation. For example... Figure 1 As shown, a first bearing 200 and a first seal 300 are independently installed at both ends of the first rotor 100, and the first bearing 200 is assembled on the outside of the first seal 300, resulting in a long bearing span between the first bearings 200, which in turn results in low stiffness of the first rotor 100.

[0046] Therefore, in some embodiments, such as Figure 2 As shown, this utility model proposes an oilless screw compressor with reduced bearing span, including a housing 10 with a second rotor 20; the housing 10 has a first assembly cavity 101 and a second assembly cavity 102 arranged outwardly on both sides of the working section 201 of the second rotor 20, and the first assembly cavity 101 and the second assembly cavity 102 are arranged adjacent to each other and communicate with each other.

[0047] The first assembly cavity 101 is fitted with a second seal 30 that surrounds the outer periphery of the second rotor 20, and the second assembly cavity 102 is fitted with a second bearing 40 that surrounds the outer periphery of the second rotor 20.

[0048] It should be noted that both the first assembly cavity 101 and the second assembly cavity 102 are annular and are arranged circumferentially around the second rotor 20. Furthermore, the first assembly cavity 101 and the second assembly cavity 102 are adjacent and interconnected, meaning that adjacent first assembly cavities 101 and 102 share the same end face, thereby bringing the second bearing 40 within the second assembly cavity 102 closer to the working section 201 of the second rotor 20. The two sides of the working section 201 of the second rotor 20 are the intake side and the exhaust side, respectively.

[0049] In this way, by having the first assembly cavity 101 and the second assembly cavity 102 arranged adjacent to each other and communicating, the second bearing 40 assembled in the second assembly cavity 102 is brought closer to the working section 201 of the second rotor 20, thereby making the structure of the first assembly cavity 101 and the second assembly cavity 102 more compact, thereby shortening the bearing span between the second bearings 40, thereby improving the stiffness of the second rotor 20, increasing the critical speed of the second rotor 20, and reducing the vibration amplitude of the second rotor 20.

[0050] Furthermore, shortening the bearing span between the second bearings 40 can reduce the overall length of the oilless screw compressor, thereby reducing the size of the oilless screw compressor.

[0051] It is understandable that the larger the bearing span between the second bearings 40, the greater the bending deformation of the second rotor 20, resulting in a smaller stiffness of the second rotor 20. Furthermore, the second rotor 20 has its inherent vibration frequency, called the "critical speed," and stiffness is one of the key factors determining the level of the critical speed.

[0052] In some embodiments, such as Figure 2 As shown, the second rotor 20 has a through oil hole 202 in the middle along the axial direction, and the through oil hole 202 is used to transport lubricating oil.

[0053] The through oil hole 202 communicates with the first assembly cavity 101 and / or the second assembly cavity 102.

[0054] It should be noted that this embodiment uses the example of the through oil hole 202 communicating with the second assembly cavity 102. Wherein, as... Figure 6 As shown, the through oil hole 202 is provided radially with at least one oil supply through hole 204 corresponding to the second assembly cavity 102, that is, the through oil hole 202 communicates with the second assembly cavity 102 through the oil supply through hole 204.

[0055] In contrast to existing technologies that require separate oil supply to the first bearing 200 and the first seal 300 at both ends of the first rotor 100, resulting in complex oil circuits and a larger size of the oilless screw compressor, this embodiment provides an axially extending oil hole 202 in the middle of the second rotor 20. The oil hole 202 communicates with the second assembly cavity 102 through an oil supply through hole 204, allowing the lubricating oil in the oil hole 202 to flow synchronously to the intake and exhaust sides of the working section 201 of the second rotor 20, and the lubricating oil in the second assembly cavity 102 to flow synchronously to the first assembly cavity 101. This reduces leakage points and forms an integrated oil circuit network with "single source and dual lubrication points." Furthermore, the oil supply does not enter the working section 201 of the second rotor 20, thus simplifying the oil supply circuit and reducing the size of the oilless screw compressor.

[0056] In some embodiments, to ensure the sealing performance of the second seal 30, prevent gas leakage, and ensure the airtightness of the oil-free screw compressor operation, such as... Figure 2 and Figure 3 As shown, this embodiment proposes a structural composition of a second sealing element 30, which includes a dynamic ring 301 and a stationary ring 302;

[0057] The first assembly cavity 101 is fitted with a stationary ring 302;

[0058] Both sides of the working section 201 of the second rotor 20 are provided with recesses 203 inwardly corresponding to the first assembly cavity 101. A moving ring 301 is installed in the recesses 203. The opposing end faces of the moving ring 301 and the stationary ring 302 are in direct contact to form a dynamic sealing interface.

[0059] It should be noted that the rotating ring 301 is fixed on both sides of the working section 201 of the second rotor 20 and rotates synchronously with the second rotor 20. Furthermore, the facing end faces (equivalent to the sealing surfaces) of the rotating ring 301 and the stationary ring 302 are planar, in order to better achieve a dynamic sealing interface and reduce the overall space occupied by the second sealing element 30. This shortens the bearing span between the second bearings 40, increases the rigidity of the second rotor 20, increases the critical speed of the second rotor 20, and reduces the vibration amplitude of the second rotor 20.

[0060] The second seal 30 installed on the intake side of the working section 201 of the second rotor 20 is used to prevent gas from flowing back in the axial direction; while the second seal 30 installed on the exhaust side of the working section 201 of the second rotor 20 is used to prevent gas from leaking from the high-pressure side to the low-pressure side.

[0061] In some embodiments, the stationary ring 302 and the second bearing 40 are in contact, or the distance between the stationary ring 302 and the second bearing 40 is not greater than 1 mm.

[0062] This design ensures that the stationary ring 302 and the second bearing 40 use the same axial positioning reference, keeping the perpendicularity error of the sealing surface of the stationary ring 302 within 0.01 mm / m. This allows for perfect contact between the opposing end faces of the rotating ring 301 and the stationary ring 302, reducing seal failure and leakage caused by uneven wear. Furthermore, since the second bearing 40 is typically one of the stiffest and best-dissipating components in the entire rotor system, the stationary ring 302 can transfer some heat to the second bearing 40, which is then carried away by the bearing housing and lubricating oil, preventing excessively high temperatures at the dynamic sealing interface.

[0063] In some embodiments, to ensure that the bearing span between the second bearings 40 is of appropriate length, balancing rigidity and compactness, and improving the reliability of the rotor system, such as... Figure 2 As shown, the bearing span L between the second bearings 40 on both sides of the working section 201 of the second rotor 20 is ≤1.2a;

[0064] Where a is the length of the working section 201 of the second rotor 20.

[0065] It should be noted that if the bearing span is too short, although it can enhance the rigidity of the second rotor 20, it will limit the heat dissipation space of the second bearing 40, resulting in excessive temperature rise of the second bearing 40; if the bearing span is too long, it will aggravate the vibration of the second rotor 20, reduce the rigidity of the second rotor 20, and reduce the critical speed of the second rotor 20.

[0066] In some embodiments, the stationary ring 302 is fixed in the first assembly cavity 101 by a fastener, and a gap is formed between the stationary ring 302 and the first assembly cavity 101 in both the radial and / or axial directions.

[0067] It should be noted that this embodiment uses the example of a radial clearance of 0.05mm-0.2mm and an axial clearance of 0.1mm-0.3mm between the stationary ring 302 and the first assembly cavity 101. Of course, the lengths of the radial and axial clearances between the stationary ring 302 and the first assembly cavity 101 can be selected as other values ​​according to the actual situation, which are not limited here.

[0068] Furthermore, the fastener proposed in this embodiment is preferably an O-ring or a spring, which is not limited here; the stationary ring 302 is pressed and fixed in the first assembly cavity 101 by the O-ring or spring.

[0069] The radial and axial clearances formed between the stationary ring 302 and the first assembly cavity 101 can compensate for the thermal expansion or assembly tolerances of the second rotor 20. The axial clearance between the stationary ring 302 and the first assembly cavity 101 allows the stationary ring 302 to float freely during assembly, dynamically compensating for the end face wear of the connecting moving ring 301. The radial clearance between the stationary ring 302 and the first assembly cavity 101 can form a stable oil film, avoiding direct friction between the stationary ring 302 and the cavity of the first assembly cavity 101, and preventing deformation or frictional heat generation of the stationary ring 302.

[0070] In some embodiments, the depth of the sink 203 is greater than the thickness of the moving ring 301, so that the sink 203 forms an axial compensation space.

[0071] It should be noted that, in this embodiment, the depth of the sink 203 is 0.2mm-0.3mm greater than the thickness of the moving ring 301, which means that the axial length of the axial compensation space is preferably 0.2mm-0.3mm. Of course, the axial length of the axial compensation space can be selected as other values ​​according to the actual situation, which is not limited here.

[0072] The axial compensation space is used for thermal expansion compensation. When the second rotor 20 rotates at high speed, it expands axially due to frictional heat. The reserved axial compensation space can prevent the rotating ring 301 from making hard contact with the bottom of the groove 203, thus preventing jamming or deformation. The axial compensation space can also allow lubricating oil to fill in, forming a lubricating layer and reducing frictional loss between the rotating ring 301 and the groove 203. The axial compensation space can also compensate for wear. After long-term wear of the end face of the rotating ring 301 connecting to the stationary ring 302, the axial displacement can maintain the effective contact pressure of the sealing surface of the rotating ring 301.

[0073] Of course, there is also a radial gap between the moving ring 301 and the settling tank 203. The radial gap is preferably 0.02mm-0.1mm. Of course, the length of the radial gap between the moving ring 301 and the settling tank 203 can be selected as other values ​​according to the actual situation, which are not limited here.

[0074] Furthermore, the radial clearance between the moving ring 301 and the sink 203 is used for guidance and heat dissipation; if it is too large, it will easily cause the moving ring 301 to become eccentric.

[0075] In some embodiments, such as Figure 4 and Figure 5 As shown, an elastic sealing ring 50 is provided between the bottom of the settling tank 203 and the end face of the moving ring 301.

[0076] It should be noted that the elastic sealing ring 50 is preferably an O-ring or a retaining ring.

[0077] The rotating ring 301 is axially fixed by the elastic sealing ring 50 at the bottom of the settling groove 203, and the outer diameter of the rotating ring 301 is interference-fitted with the inner wall of the settling groove 203 to achieve radial fixation.

[0078] In this way, the elastic sealing ring 50 provides axial constraint force through pre-compression deformation, preventing the moving ring 301 from detaching from the sink 203 due to centrifugal force when the second rotor 20 rotates at high speed; and the elastic sealing ring 50 can also absorb the axial vibration of the second rotor 20, avoiding wear caused by hard contact between the moving ring 301 and the bottom of the sink 203.

[0079] In some embodiments, to ensure the sealing performance of the rotating ring 301 and the stationary ring 302, the rotating ring 301 is made of a hard material and the stationary ring 302 is made of a soft material.

[0080] It should be noted that the hard material is tungsten carbide, silicon carbide, tungsten-cobalt cemented carbide, or other materials with a hardness ≥ HRC50 and high wear resistance (wear rate ≤ 0.01 mm / 1000 hours), and is not limited here. The soft material is graphite, polytetrafluoroethylene, or other materials with self-lubricating properties (friction coefficient 0.05-0.15) and high thermal conductivity, and is not limited here.

[0081] This utility model also proposes a water chiller unit, which includes the oil-free screw compressor described above.

[0082] In this embodiment, the first assembly cavity 101 and the second assembly cavity 102 are arranged adjacently and communicate with each other, so that the second bearing 40 assembled in the second assembly cavity 102 is closer to the working section 201 of the second rotor 20, thereby making the structure of the first assembly cavity 101 and the second assembly cavity 102 more compact, thereby shortening the bearing span between the second bearings 40, thereby improving the rigidity of the second rotor 20, increasing the critical speed of the second rotor 20, reducing the vibration amplitude of the second rotor 20, and extending the service life of the screw compressor and chiller unit.

[0083] Furthermore, shortening the bearing span between the second bearings 40 can reduce the overall length of the oilless screw compressor. At the same time, a through oil hole 202 is provided axially in the middle of the second rotor 20. The through oil hole 202 communicates with the second assembly cavity 102 through the oil supply through hole 204, so that the lubricating oil in the through oil hole 202 can flow synchronously to the suction side and the exhaust side of the working section 201 of the second rotor 20, and the lubricating oil in the second assembly cavity 102 can flow synchronously to the first assembly cavity 101, reducing leakage points and forming an integrated oil circuit network of "single source dual lubrication point". Moreover, the oil supply will not enter the working section 201 of the second rotor 20, thereby simplifying the oil supply circuit and reducing the size of the oilless screw compressor.

[0084] Obviously, the embodiments described above are only some embodiments of this utility model, not all embodiments. The accompanying drawings show preferred embodiments of this utility model, but do not limit the patent scope of this utility model. This utility model can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this utility model specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this utility model.

Claims

1. An oil-free screw compressor, comprising a housing (10) with a second rotor (20); characterized in that, The housing (10) has a first assembly cavity (101) and a second assembly cavity (102) arranged outwardly on both sides of the working section (201) of the second rotor (20), and the first assembly cavity (101) and the second assembly cavity (102) are arranged adjacent to each other and communicate with each other. The first assembly cavity (101) is fitted with a second seal (30) arranged around the outer periphery of the second rotor (20), and the second assembly cavity (102) is fitted with a second bearing (40) arranged around the outer periphery of the second rotor (20).

2. The oil-free screw compressor according to claim 1, characterized in that, The second rotor (20) has a through oil hole (202) in the middle along the axial direction, and the through oil hole (202) is used to transport lubricating oil; The through oil hole (202) communicates with the first assembly cavity (101) and / or the second assembly cavity (102).

3. The oil-free screw compressor according to claim 1, characterized in that, The second seal (30) includes a rotating ring (301) and a stationary ring (302); The first assembly cavity (101) is fitted with a stationary ring (302); The working section (201) of the second rotor (20) has a groove (203) on both sides corresponding to the first assembly cavity (101). A moving ring (301) is installed in the groove (203). The end faces of the moving ring (301) and the stationary ring (302) directly contact each other to form a dynamic sealing interface.

4. The oil-free screw compressor according to claim 3, characterized in that, The stationary ring (302) and the second bearing (40) are in contact, or the distance between the stationary ring (302) and the second bearing (40) is not greater than 1 mm.

5. The oil-free screw compressor according to claim 3, characterized in that, The bearing span L between the second bearings (40) on both sides of the working section (201) of the second rotor (20) is ≤1.2a; Where a is the length of the working section (201) of the second rotor (20).

6. The oil-free screw compressor according to claim 3, characterized in that, The stationary ring (302) is fixed in the first assembly cavity (101) by a fastener, and a gap is formed between the stationary ring (302) and the first assembly cavity (101) in both the radial and / or axial directions.

7. The oil-free screw compressor according to claim 3, characterized in that, The depth of the settling groove (203) is greater than the thickness of the moving ring (301) so that the settling groove (203) forms an axial compensation space.

8. The oil-free screw compressor according to claim 3, characterized in that, An elastic sealing ring (50) is provided between the bottom of the settling tank (203) and the end face of the moving ring (301).

9. The oil-free screw compressor according to claim 3, characterized in that, The moving ring (301) is made of a hard material, and the stationary ring (302) is made of a soft material.

10. A water chiller unit, characterized in that, The chiller unit includes an oil-free screw compressor as described in any one of claims 1 to 9.

Images