Dry oil-free screw compressor

Abstract

The present invention relates to a dry oil-free screw compressor, comprising a housing and a main transmission shaft, a gear transmission assembly and a male and female screw transmission pair installed in the housing; the housing comprises a gear box housing, an intermediate body and a compressor body housing which are sealed and fastened in sequence, and an axial air inlet port and a top exhaust port are provided on the compressor body housing; the lower space of the inner cavity of the gear box housing, the lower space of the inner cavity of the intermediate body and the lower space of the inner cavity of the compressor body housing are connected to form a lubricating oil holding chamber; the axial air inlet port is connected to the compression chamber through an arc channel, and part of the bottom surface of the arc channel can contact the lubricating oil in the lubricating oil holding chamber; the exhaust side sealing assembly comprises an oil seal assembly, an air seal assembly and a breathable pressure ring arranged between the oil seal assembly and the air seal assembly. The housing in the present application is divided into three parts, and the structural design is reasonable, compact, small in size, and occupies a small installation space, which is more suitable for vehicle-mounted, making it very suitable for installation on the chassis of most vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and in particular to a dry oil-free screw compressor. Background Art

[0002] The dry oil-free screw compressor is a twin-screw compressor, and there is no lubrication in its compression chamber, but lubricating oil is required in the gearbox. Therefore, a corresponding cavity is usually required in the compressor housing to store sufficient lubricating oil. Long-term operation of the compressor will cause the temperature of the lubricating oil to rise, which requires the installation of a corresponding oil cooling device, resulting in a large compressor volume and a large installation space, which is not suitable for vehicle-mounted use. For example, the patent with the authorization announcement number CN203742985U: Oil-free dry screw air compressor, the compressor is designed with a corresponding cooler for cooling the oil, resulting in a large compressor volume, thereby increasing the installation space. In addition, the existing compressor housing has the disadvantage of not being compact enough, and the sealing structure at the end of the screw has the disadvantage of poor sealing effect. Often a small amount of lubricating oil still enters the compression chamber, thereby affecting the quality of the compressed gas. Therefore, it is necessary to improve and optimize the existing dry oil-free screw compressor. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a dry oil-free screw compressor with a reasonable and compact structure.

[0004] The technical solution adopted by the present invention to solve the above-mentioned problems is: a dry oil-free screw compressor, comprising a shell and a main transmission shaft, a gear transmission assembly and a male and female screw transmission pair installed in the shell, the main transmission shaft drives the male and female screw transmission pair through the gear transmission assembly; the male and female screw transmission pair comprises a pair of male and female screws meshing with each other and arranged in parallel, an intake side sealing assembly and an exhaust side sealing assembly are respectively arranged at both ends of the male and female screws, and bearing assemblies are also arranged; it is characterized in that: the shell comprises a gear box shell, an intermediate body and a compressor body shell which are sealed and fastened in sequence, an axial intake port and a top exhaust port are opened on the compressor body shell; the upper space of the inner cavity of the gear box shell is the installation space of the gear transmission assembly, and the upper part of the inner cavity of the intermediate body is provided with a accommodating cavity for installing the exhaust side sealing assembly and the bearing assembly installed at the exhaust end of the male and female screws. , a compression chamber for installing a male and female screw transmission pair is provided at the upper part of the inner cavity of the compressor body shell; the lower space of the inner cavity of the gear box shell, the lower space of the inner cavity of the intermediate body and the lower space of the inner cavity of the compressor body shell are connected to form a lubricating oil holding chamber; the axial air inlet port is located at a side and lower position of the compression chamber, and the axial air inlet port is connected to the compression chamber through an arc-shaped channel, and part of the bottom surface of the arc-shaped channel can contact the lubricating oil in the lubricating oil holding chamber; the exhaust side sealing assembly includes an oil seal assembly, an air seal assembly and a breathable pressure ring arranged between the oil seal assembly and the air seal assembly, the oil seal assembly is arranged close to the side of the gear transmission assembly, and the air seal assembly is arranged close to the side of the male and female screw transmission pair, one side of the breathable pressure ring abuts against the oil seal assembly, and the other side of the breathable pressure ring abuts against the air seal assembly, and a circle of breathable grooves is opened at the intermediate body box wall corresponding to the breathable pressure ring, and the breathable grooves are connected to the outside atmosphere.

[0005] Preferably, an oil inlet passage and an oil return passage are provided in the wall of the shell; an oil pump is installed on one side of the gear box shell; one end of the oil inlet passage is connected to the lubricating oil containing chamber, and the other end of the oil inlet passage is connected to the oil inlet of the oil pump; one end of the oil return passage is connected to the oil outlet of the oil pump, and a plurality of lubricating oil outlets are provided on the oil return passage according to the positions of the parts to be lubricated installed in the gear box shell.

[0006] Preferably, reinforcing ribs are provided between the bottom of the arc-shaped channel and the bottom surface of the compressor body shell.

[0007] Preferably, an oil sight glass mounting hole is provided on one side of the gear box housing, in which an oil sight glass for observing the oil amount in the lubricating oil containing chamber is installed; and a grease injection hole is provided on one side of the compressor body housing for injecting grease into the bearing assembly installed on the air inlet side of the male screw and the female screw.

[0008] Preferably, a breathable cap mounting hole and a lifting hole are provided on the top of the intermediate body, and the breathable cap mounting hole is used to install the breathable cap; and an oil drain hole is provided on the bottom of the intermediate body.

[0009] Preferably, the gear transmission assembly includes a primary driving gear, a primary driven gear, a secondary driving gear, a secondary driven gear and a driven shaft; the driven shaft is arranged in parallel with the main transmission shaft, the primary driven gear and the secondary driving gear are both installed on the driven shaft, the primary driving gear is installed on the main transmission shaft, the primary driving gear is meshed with the primary driven gear, the secondary driving gear is meshed with the secondary driven gear, the secondary driven gear is installed at the end of the male screw, and a pair of synchronous gears are installed at the ends of the male screw and the female screw; the rotor of the oil pump is connected to the driven shaft.

[0010] Preferably, the gearbox housing and the intermediate body, as well as the intermediate body and the compressor body housing are fastened together by bolts.

[0011] Preferably, the oil seal assembly adopts a non-contact labyrinth oil seal ring, an O-ring is sleeved on the outside of the non-contact labyrinth oil seal ring, and the O-ring is in contact with the wall of the intermediate box.

[0012] Preferably, the air sealing assembly comprises a No. 1 air sealing ring, a No. 1 wave spring, an air sealing seat, a No. 2 air sealing ring and a No. 2 wave spring which are arranged in sequence, wherein the No. 1 air sealing ring abuts against a breathable pressure ring.

[0013] Preferably, the shaft sections at the ends of both the male screw and the female screw for mounting the air-permeable pressure ring are stepped shafts.

[0014] Compared with the prior art, the present invention has the following advantages and effects:

[0015] 1. The shell is divided into three parts, with reasonable structural design, compact size, small installation space, more suitable for vehicle installation, making it very suitable for installation on the chassis of most vehicles;

[0016] 2. The installation space of the gear transmission assembly, the installation space of the screw exhaust side seal assembly and the bearing assembly, and the compression chamber for installing the screw are arranged in the upper part of the shell, and the lower part of the shell is used as the lubricating oil holding chamber, and the axial air inlet port is connected with the compression chamber through an arc channel. Part of the bottom surface of the arc channel can contact the lubricating oil in the lubricating oil holding chamber, and the external gas can play a certain cooling effect on the lubricating oil in the lubricating oil holding chamber when passing through the arc channel;

[0017] 3. In the design of the screw exhaust side sealing assembly, a breathable pressure ring is set between the oil seal and the gas seal, and a circle of breathable grooves is set on the intermediate box wall corresponding to the breathable pressure ring. The breathable groove is connected to the outside atmosphere and can play a role in pressure relief to prevent the air pressure here from being too high. In addition, the section of the screw shaft where the breathable pressure ring is installed is designed as a stepped shaft. When a small amount of lubricating oil leaks from the oil seal, the stepped shaft plays a certain blocking role on the lubricating oil to prevent the lubricating oil from leaking to the gas seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a schematic structural diagram of a dry oil-free screw compressor according to an embodiment of the present invention.

[0020] Figure 2 Schematic diagram of the structure of the compressor housing in an embodiment of the present invention.

[0021] Figure 3 yes Figure 2 Schematic diagram of the explosion structure.

[0022] Figure 4 It is a schematic diagram of the main structure of the compressor housing in an embodiment of the present invention.

[0023] Figure 5 yes Figure 4 AA section diagram (showing part of the oil inlet passage).

[0024] Figure 6 yes Figure 4 Schematic diagram of the CC section structure (showing part of the oil outlet channel).

[0025] Figure 7 Schematic diagram of the top view of the compressor housing in an embodiment of the present invention.

[0026] Figure 8 yes Figure 7 BB section structure schematic diagram.

[0027] Fig. 9 It is a schematic diagram of the three-dimensional structure of the compressor body shell in an embodiment of the present invention.

[0028] Fig.10 It is a schematic diagram of the connection relationship between the gear transmission assembly and the male and female screws in an embodiment of the present invention.

[0029] Fig.11 It is a schematic structural diagram of the male screw exhaust side sealing assembly in an embodiment of the present invention.

[0030] Fig.12 It is a schematic structural diagram of the air-permeable pressure ring of the exhaust side sealing assembly in an embodiment of the present invention.

[0031] Description of reference numerals: housing 1, oil pump 2, main transmission shaft 3, gearbox housing 11, intermediate body 16, compressor body housing 12, lubricating oil containing chamber 13, oil inlet passage 14, oil return passage 15, oil sight glass mounting hole 111, breathable cap mounting hole 112, lifting hole 113, oil drain hole 114, axial air inlet port 121, top exhaust port 122, compression chamber 123, arc channel 124, reinforcing rib 125, grease injection hole 126, lubrication Oil outlet 151, accommodating chamber 161, air permeable groove 162, first-stage driving gear 41, first-stage driven gear 42, second-stage driving gear 43, second-stage driven gear 44, driven shaft 45, synchronous gear 46, male screw 51, female screw 52, ​​air permeable pressure ring 6, air hole 611, non-contact labyrinth oil seal ring 7, O-ring 8, No. 2 wave spring 9, air seal seat 10, No. 1 air seal ring 21, No. 1 wave spring 22, No. 2 air seal ring 23. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0033] Example

[0034] See also Figures 1 to 12 .

[0035] This embodiment discloses a dry oil-free screw compressor, comprising a housing 1, an oil pump 2, a main transmission shaft 3, a gear transmission assembly, and a male and female screw transmission pair installed in the housing 1. The main transmission shaft 3 drives the male and female screw transmission pair through the gear transmission assembly; the male and female screw transmission pair comprises a pair of male screws 51 and female screws 52 meshing with each other and arranged in parallel, and an intake side sealing assembly and an exhaust side sealing assembly are respectively arranged at both ends of the male screw 51 and the female screw 52, ​​and a bearing assembly is also arranged on both ends.

[0036] In this embodiment, the gear transmission assembly includes a primary driving gear 41, a primary driven gear 42, a secondary driving gear 43, a secondary driven gear 44 and a driven shaft 45; the driven shaft 45 is arranged in parallel with the main transmission shaft 3, the primary driven gear 42 and the secondary driving gear 43 are both mounted on the driven shaft 45, the primary driving gear 41 is mounted on the main transmission shaft 3, the primary driving gear 41 is meshed with the primary driven gear 42, the secondary driving gear 43 is meshed with the secondary driven gear 44, the secondary driven gear 44 is mounted at the end of the male screw 51, and a pair of synchronous gears 46 are mounted at the ends of the male screw 51 and the female screw 52. When the compressor is working, the main transmission shaft 3 is connected to an external motor, and after the secondary gear increases the speed, it drives a pair of male screws 51 and female screws 52 to rotate, thereby compressing the air. The maximum exhaust pressure that this compressor can generate is 2.5 barg, which is very suitable for pollution-free transportation of various powders and granular products.

[0037] In this embodiment, the housing 1 includes a gearbox housing 11, an intermediate body 16 and a compressor body housing 12 which are connected in sequence by bolt sealing and fastening. The upper space of the inner cavity of the gearbox housing 11 is a gear transmission assembly installation space. The upper inner cavity of the intermediate body 16 is provided with two accommodating chambers 161 for installing the exhaust side sealing assembly and the bearing assembly installed at the exhaust end of the male screw 51 and the female screw 52. The upper inner cavity of the compressor body housing 12 is provided with a compression chamber 123 for installing the male and female screw transmission pairs. The lower inner cavity space of the gearbox housing 11, the lower inner cavity space of the intermediate body 16 and the lower inner cavity space of the compressor body housing 12 are connected to form a lubricating oil holding chamber 13, and the lubricating oil holding chamber 13 is used to hold the lubricating oil required for the gears and bearings.

[0038] In this embodiment, an axial air inlet port 121 and a top exhaust port 122 are provided on the compressor body shell 12; wherein the axial air inlet port 121 is located at the side and lower position of the compression chamber 123, and the axial air inlet port 121 is connected to the compression chamber 123 through an arc-shaped channel 124, and a reinforcing rib 125 is provided between the bottom of the arc-shaped channel 124 and the bottom surface of the compressor body shell 12. Two grease injection holes 126 for injecting grease into the bearing assembly of the air inlet end of the male and female screws are provided on one side of the compressor body shell 12.

[0039] In this embodiment, the lubricating oil in the lubricating oil holding chamber 13 is used for oil lubrication of gears and bearings. After the compressor has been working for a period of time, the temperature of the lubricating oil will increase. In this embodiment, part of the bottom surface of the arc-shaped channel 124 can contact the lubricating oil in the lubricating oil holding chamber 13, so when the external gas passes through the arc-shaped channel 124, it can play a certain cooling effect on the lubricating oil in the lubricating oil holding chamber 13. In addition, the external gas first enters the axial air inlet port 121 along the axial direction, and then enters the compression chamber 123 radially after completing a 90° turn through the arc-shaped channel 124, and the gas enters smoothly.

[0040] In this embodiment, an oil inlet passage 14 and an oil return passage 15 are provided in the wall of the housing 1. An oil pump 2 is installed on one side of the gearbox housing 11, and the rotor of the oil pump 2 is connected to the driven shaft 45. One end of the oil inlet passage 14 is connected to the lubricating oil holding chamber 13, and the other end of the oil inlet passage 14 is connected to the oil inlet of the oil pump 2; one end of the oil return passage 15 is connected to the oil outlet of the oil pump 2, and a plurality of lubricating oil outlets 151 are provided on the oil return passage 15 according to the positions of the parts to be lubricated installed in the gearbox housing 11. The lubricating oil in the lubricating oil holding chamber 13 is transported to the gears and bearings of the parts to be lubricated by the action of the oil pump 2, and then the lubricating oil on the parts drips into the lubricating oil holding chamber 13 under the action of gravity.

[0041] Specifically, refer to Figures 3 to 6 , with the side to which the top exhaust port 122 is biased as the front side, a portion of the oil inlet passage 14 is opened in the front wall surface of the gearbox housing 11, the intermediate body 16 and the compressor body housing 12, and then extends upward, extending the oil inlet passage 14 to the left wall surface of the gearbox housing 11, and the oil pump 2 is installed on the left wall surface. Correspondingly, the oil return passage 15 is first opened on the left wall surface of the gearbox housing 11, and then extends backward to the rear wall surface of the intermediate body 16. The setting of the lubricating oil outlet 151 should ensure that the bearings and gears are fully lubricated, refer to Figure 6 The two lubricating oil outlets 151 located at the top are used to meet the lubrication needs of the bearings located below them; the lubricating oil outlet 151 located at the bottom is connected to the oil return channel 15, and an oil spray nozzle is installed here for oil spray lubrication of the gears.

[0042] In this embodiment, an oil sight glass mounting hole 111 is provided on one side of the gearbox housing 11, and an oil sight glass is installed in the oil sight glass mounting hole 111, so that it can be checked whether the amount of lubricating oil in the lubricating oil holding chamber 13 is sufficient. A breathable cap mounting hole 112 and a hoisting hole 113 are provided on the top of the intermediate body 16. A breathable cap is installed at the breathable cap mounting hole 112 for ventilation. When the compressor is used for the first time, a sufficient amount of lubricating oil is added to the lubricating oil holding chamber 13 through the breathable cap mounting hole 112. The hoisting hole 113 is convenient for hoisting during the production and assembly of the compressor. An oil drain hole 114 is provided at the bottom of the intermediate body 16, and the lubricating oil in the lubricating oil holding chamber 13 is discharged through the oil drain hole 114.

[0043] In this embodiment, the exhaust side sealing assembly includes an oil seal assembly, an air seal assembly and a breathable pressure ring 6 arranged between the oil seal assembly and the air seal assembly. The oil seal assembly is arranged close to the gear transmission assembly side, and the air seal assembly is arranged close to the yin and yang screw transmission pair side. The breathable pressure ring 6 has a circle of air holes 611. One side of the breathable pressure ring 6 abuts against the oil seal assembly, and the other side of the breathable pressure ring 6 abuts against the air seal assembly. A circle of breathable grooves 162 are opened on the box wall of the intermediate body 16 corresponding to the breathable pressure ring 6. The breathable grooves 162 are connected to the outside atmosphere, which can play a role in pressure relief and prevent the air pressure here from being too high.

[0044] In this embodiment, the oil seal assembly adopts a non-contact labyrinth oil seal ring 7, which is used to seal the lubricating oil of the gear box to prevent the lubricating oil from leaking into the compression chamber. An O-type sealing ring 8 is sleeved on the outside of the non-contact labyrinth oil seal ring 7, and the O-type sealing ring 8 is in contact with the box wall of the intermediate body 16. Of course, in other embodiments, the oil seal assembly can also adopt a contact oil seal, as long as it can prevent the lubricating oil from leaking into the compression chamber.

[0045] In the present embodiment, the air seal assembly includes a No. 1 air seal ring 21, a No. 1 wave spring 22, an air seal seat 10, a No. 2 air seal ring 23 and a No. 2 wave spring 9 which are arranged in sequence, wherein the No. 1 air seal ring 21 abuts against the breathable pressure ring 6. Two air seal rings are arranged in the air seal assembly, which can achieve a good air seal effect and prevent the high-pressure gas in the compression chamber from leaking out, and two wave springs are arranged, which ensure that the air seal performance of the air seal assembly is not affected when a small amount of axial movement of the male and female screws occurs. The air seal assembly in the present embodiment is a non-contact seal, which can effectively prevent the high-pressure gas in the compression chamber from leaking out, and has a certain pressure relief function to prevent excessive air pressure at the air seal. Of course, in other embodiments, the air seal assembly may also adopt a contact seal, as long as the air seal effect is met.

[0046] In this embodiment, the shaft sections at the ends of both the male screw 51 and the female screw 52 for mounting the breathable pressure ring 6 are stepped shafts. When a small amount of lubricating oil leaks out from the oil seal, the stepped shafts have a certain blocking effect on the lubricating oil, preventing the lubricating oil from leaking to the air seal.

[0047] In this embodiment, the bearing assembly installed on the air inlet side of the male and female screws is grease lubricated, so the sealing on the air inlet side of the male and female screws can be a contact oil seal. For details, please refer to the existing technology and will not be elaborated here.

[0048] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles of the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A dry oil-free screw compressor, comprising a housing (1) and a main transmission shaft (3), a gear transmission assembly and a male-female screw transmission pair installed in the housing (1), wherein the main transmission shaft (3) drives the male-female screw transmission pair through the gear transmission assembly; the male-female screw transmission pair comprises a pair of male screws (51) and female screws (52) meshing with each other and arranged in parallel, an air intake side sealing assembly and an exhaust side sealing assembly are respectively arranged at both ends of the male screw (51) and the female screw (52), and both are provided with bearing assemblies; Features: The housing (1) comprises a gearbox housing (11), an intermediate body (16) and a compressor body housing (12) which are sealed and fastened in sequence, and the compressor body housing (12) is provided with an axial air inlet port (121) and a top exhaust port (122); the upper space of the inner cavity of the gearbox housing (11) is a gear transmission assembly installation space, and the upper part of the inner cavity of the intermediate body (16) is provided with an accommodating cavity (161) for installing an exhaust side sealing assembly and a bearing assembly installed at the exhaust ends of the male screw (51) and the female screw (52); the compressor body housing (1 2) is provided with a compression chamber (123) for mounting a male and female screw transmission pair at the upper portion of the inner chamber; the lower inner chamber space of the gear box housing (11), the lower inner chamber space of the intermediate body (16) and the lower inner chamber space of the compressor body housing (12) are connected to form a lubricating oil containing chamber (13); the axial air inlet port (121) is located at a side lower position of the compression chamber (123), the axial air inlet port (121) is connected to the compression chamber (123) via an arc-shaped channel (124), and a portion of the bottom surface of the arc-shaped channel (124) can contact the lubricating oil in the lubricating oil containing chamber (13); The exhaust side sealing assembly comprises an oil seal assembly, an air seal assembly and a breathable pressure ring (6) arranged between the oil seal assembly and the air seal assembly, the oil seal assembly being arranged close to the gear transmission assembly side, the air seal assembly being arranged close to the male and female screw transmission pair side, one side of the breathable pressure ring (6) abutting against the oil seal assembly, and the other side of the breathable pressure ring (6) abutting against the air seal assembly, a circle of breathable grooves (162) being provided on the box wall of the intermediate body (16) corresponding to the breathable pressure ring (6), the breathable grooves (162) being in communication with the outside atmosphere; An oil inlet passage (14) and an oil return passage (15) are provided in the wall of the housing (1); an oil pump (2) is installed on one side of the gearbox housing (11); one end of the oil inlet passage (14) is connected to the lubricating oil storage chamber (13), and the other end of the oil inlet passage (14) is connected to the oil inlet of the oil pump (2); one end of the oil return passage (15) is connected to the oil outlet of the oil pump (2), and a plurality of lubricating oil outlets are provided on the oil return passage (15) according to the positions of the components to be lubricated installed in the gearbox housing (11); The gear transmission assembly comprises a primary driving gear (41), a primary driven gear (42), a secondary driving gear (43), a secondary driven gear (44) and a driven shaft (45); the driven shaft (45) is arranged in parallel with the main transmission shaft (3); the primary driven gear (42) and the secondary driving gear (43) are both mounted on the driven shaft (45); the primary driving gear (41) is mounted on the main transmission shaft (3); the primary driving gear (41) meshes with the primary driven gear (42); the secondary driving gear (43) meshes with the secondary driven gear (44); the secondary driven gear (44) is mounted at the end of the male screw (51); and a pair of synchronous gears (46) are mounted at the ends of the male screw (51) and the female screw (52); the rotor of the oil pump (2) is connected to the driven shaft (45); The top of the intermediate body (16) is provided with a breathable cap mounting hole (112) and a hanging hole (113), wherein the breathable cap mounting hole (112) is used for mounting the breathable cap; and the bottom of the intermediate body (16) is provided with an oil drain hole (114).

2. The dry oil-free screw compressor according to claim 1, characterized in that: A reinforcing rib (125) is provided between the bottom of the arc-shaped channel (124) and the bottom surface of the compressor body shell (12).

3. The dry oil-free screw compressor according to claim 1, characterized in that: An oil sight glass mounting hole (111) is provided on one side of the gearbox housing (11), and an oil sight glass for observing the amount of oil in the lubricating oil containing chamber (13) is installed in the oil sight glass mounting hole (111); and a grease injection hole (126) for injecting grease into the bearing assembly installed on the air inlet side of the male screw rod (51) and the female screw rod (52) is provided on one side of the compressor body housing (12).

4. The dry oil-free screw compressor according to claim 1, characterized in that: The gear box housing (11) and the intermediate body (16), as well as the intermediate body (16) and the compressor body housing (12) are all fastened together by bolts.

5. The dry oil-free screw compressor according to claim 1, characterized in that: The oil seal assembly adopts a non-contact labyrinth oil seal ring (7), an O-type sealing ring (8) is sleeved on the outside of the non-contact labyrinth oil seal ring (7), and the O-type sealing ring (8) is in contact with the wall of the intermediate body (16) box.

6. The dry oil-free screw compressor according to claim 1, characterized in that: The gas seal assembly comprises a No. 1 gas seal ring (21), a No. 1 wave spring (22), a gas seal seat (10), a No. 2 gas seal ring (23) and a No. 2 wave spring (9) which are arranged in sequence, wherein the No. 1 gas seal ring (21) abuts against the air permeable pressure ring (6).

7. The dry oil-free screw compressor according to claim 1, characterized in that: The ends of the male screw rod (51) and the female screw rod (52) are both stepped shafts for mounting the air-permeable pressure ring (6).

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