Oil-free screw compressors

Abstract

The present invention discloses an oil-free screw compressor, comprising a driving mechanism, a first screw compressor device, a second screw compressor device and a first transmission assembly, and a third screw compression device may also be provided. The first screw compression device discharges the compressed gas into the second screw compression device, which is further compressed by the second screw compression device; the screw compression device comprises a housing, a driving screw, a driven screw and a synchronous gear set, the driving screw drives the driven screw through the synchronous gear set and realizes contactless operation of the driving screw and the driven screw; the transmission assembly comprises a driving gear and a driven gear; the driving gear is provided on the first driving screw or the first driven screw, and drives the driven gear provided on the second driving screw, thereby driving the second screw compression device; the second screw compression device is provided with a flexible volume ratio slide valve. The oil-free screw compressor proposed by the present invention simplifies the structure of the multi-stage oil-free screw compressor, reduces the equipment production cost and improves the efficiency of the compressor.

Description

[0001] This application is a divisional application of the invention patent with application number 202410645751.2 and invention name "Oil-free Screw Compressor". Technical Field

[0002] The invention belongs to the technical field of screw compression equipment and relates to a screw compressor, in particular to a novel oil-free screw compressor. Background Art

[0003] Screw compressors can be divided into oil-filled screw compressors and oil-free screw compressors. During the operation of oil-free screw compressors, there is no lubricating oil in the compression chamber, and synchronous gears are usually required. The active rotor drives the driven rotor through the synchronous gears.

[0004] Oil-free screw compressors cannot achieve compression with a large compression ratio due to the lack of oil in the compression chamber. In order to achieve oil-free compression at a higher pressure, two-stage compression or three-stage compression is usually adopted. Conventional designs usually use a driving gear to drive two driven gears. The driving gear is set on the drive shaft and driven by a driving mechanism; the two driven gears are respectively set on the male rotor of the first-stage oil-free screw compressor and the second-stage oil-free screw compressor to achieve drive. In addition, some manufacturers set up two driving mechanisms to drive the first-stage oil-free screw compressor and the second-stage oil-free screw compressor respectively.

[0005] Oil-free screw compressors require high speeds to achieve optimal performance, typically reaching tens of thousands of rpm. The high speed of oil-free screw compressors, which utilize a single driving gear driving two driven gears, results in higher speeds for the first and second stage speed-increasing gears, larger driving gears, a complex gearbox structure, and expensive transmission gears. Furthermore, the high speeds result in high gear windage and meshing losses. This high speed also results in high noise levels. While this structure is feasible for two-stage compression, it is structurally unfeasible in operating conditions requiring three-stage compression.

[0006] The technical solution of using two separate drive mechanisms typically requires two high-speed motors, which in turn requires two oil-free screw compressor systems with a higher degree of integration. This is disadvantageous in terms of overall size and cost. Similarly, when three-stage oil-free compression is required, structural implementation is even more difficult.

[0007] In view of this, there is an urgent need to design a new oil-free screw compressor so as to overcome at least some of the above-mentioned defects of the existing oil-free screw compressors. Summary of the Invention

[0008] The present invention provides an oil-free screw compressor, which can reduce the volume of the equipment and lower the production cost of the equipment.

[0009] In order to solve the above technical problems, according to one aspect of the present invention, the following technical solution is adopted:

[0010] An oil-free screw compressor, comprising: a driving mechanism, a first screw compression device, a second screw compression device and a first transmission assembly;

[0011] The driving mechanism is connected to the first screw compression device to drive the first screw compression device to work; the first screw compression device is connected to the second screw compression device through the first transmission assembly to drive the second screw compression device to work;

[0012] The first screw compression device discharges the compressed gas into the second screw compression device, which further compresses the gas.

[0013] The first screw compression device includes a first housing, a first driving screw, a first driven screw and a first synchronous gear set; the first driving screw and the first driven screw are disposed in the first housing; the first synchronous gear set includes a first driving synchronous gear and a first driven synchronous gear, the first driving synchronous gear meshing with the first driven synchronous gear;

[0014] The first active synchronous gear is provided on the rotation axis of the first active screw and is coaxial with the rotation axis of the first active screw; the first driven synchronous gear is provided on the rotation axis of the first driven screw and is coaxial with the rotation axis of the first driven screw;

[0015] The driving mechanism is connected to the first active screw to drive the first active screw to rotate; the rotation of the first active screw drives the first active synchronous gear to rotate, and the first active synchronous gear drives the first driven synchronous gear to rotate, thereby driving the first driven screw to rotate;

[0016] The second screw compression device includes a second housing, a second driving screw, a second driven screw and a second synchronous gear set; the second driving screw and the second driven screw are disposed in the second housing; the second synchronous gear set includes a second driving synchronous gear and a second driven synchronous gear, and the second driving synchronous gear is meshed with the second driven synchronous gear;

[0017] The second driving synchronous gear is provided on the rotation axis of the second driving screw and is coaxial with the rotation axis of the second driving screw; the second driven synchronous gear is provided on the rotation axis of the second driven screw and is coaxial with the rotation axis of the second driven screw;

[0018] The first transmission assembly includes a first driving gear and a first driven gear, wherein the first driving gear is meshed with the first driven gear;

[0019] The first driving gear is arranged on the rotation axis of the first driving screw or the first driven screw, and the first driven gear is arranged on the rotation axis of the second driving screw; the first driving gear can drive the first driven gear to rotate, thereby driving the second driving screw to rotate; the rotation of the second driving screw drives the second driving synchronous gear to rotate, and the second driving synchronous gear drives the second driven synchronous gear to rotate, thereby driving the second driven screw to rotate.

[0020] As an embodiment of the present invention, the oil-free screw compressor further includes a third screw compression device and a second transmission assembly;

[0021] The first screw compression device is connected to the third screw compression device through the second transmission assembly to drive the third screw compression device to work;

[0022] The second screw compression device discharges the compressed gas into the third screw compression device, which further compresses the gas.

[0023] The third screw compression device includes a third housing, a third driving screw, a third driven screw and a third synchronous gear set; the third driving screw and the third driven screw are disposed in the third housing; the third synchronous gear set includes a third driving synchronous gear and a third driven synchronous gear, and the third driving synchronous gear is meshed with the third driven synchronous gear;

[0024] The third driving synchronous gear is provided on the rotation axis of the third driving screw and is coaxial with the rotation axis of the third driving screw; the third driven synchronous gear is provided on the rotation axis of the third driven screw and is coaxial with the rotation axis of the third driven screw;

[0025] The second transmission assembly includes a second driving gear and a second driven gear, and the second driving gear is meshed with the second driven gear;

[0026] The second driving gear is arranged on the rotation axis of the first driving screw or the first driven screw, and the second driven gear is arranged on the rotation axis of the third driving screw; the second driving gear can drive the second driven gear to rotate, thereby driving the third driving screw to rotate; the rotation of the third driving screw drives the third driving synchronous gear to rotate, and the third driving synchronous gear drives the third driven synchronous gear to rotate, thereby driving the third driven screw to rotate.

[0027] As an embodiment of the present invention, the first screw compression device is connected to the third screw compression device through the second transmission assembly to drive the third screw compression device to work; the second driving synchronous gear, the second driven synchronous gear, the first transmission assembly and the second transmission assembly are arranged in the same gear box;

[0028] The first screw compression device is connected to and drives the second screw compression device through a first transmission assembly, and the first screw compression device is connected to and drives the third screw compression device through a second transmission assembly;

[0029] The first driving gear of the first transmission assembly and the second driving gear of the second transmission assembly are the same component; the first synchronous gear set, the first driving gear, the first driven gear and the second driven gear are arranged in the same gear box;

[0030] The third screw compression device is provided with a third air inlet and a third exhaust port; the second exhaust port of the second screw compression device is connected to the third air inlet through a second exhaust channel, and the gas compressed by the second screw compression device is discharged into the third screw compression device.

[0031] As an embodiment of the present invention, the oil-free screw compression is a three-stage compressor, and the first screw compression device or the second screw compression device or the third screw compression device serves as the third-stage screw compression device; a flexible volume ratio slide valve is arranged in the casing of the third-stage screw compressor to achieve optimal matching of the exhaust pressure and the required pressure.

[0032] As an embodiment of the present invention, the first screw compression device is provided with a first air inlet and a first air outlet, and the second screw compression device is provided with a second air inlet and a second air outlet;

[0033] The exhaust end of the first screw compression device is connected to the second air inlet through an exhaust channel, so that the gas compressed by the first screw compression device is discharged into the second screw compression device.

[0034] As an embodiment of the present invention, the first driving synchronous gear, the first driven synchronous gear and the first transmission assembly are arranged in the same gear box.

[0035] As an embodiment of the present invention, the first active screw is a female rotor of a first screw compression device, and the first driven screw is a male rotor of the first screw compression device; the driving mechanism drives the female rotor of the first screw compression device to rotate, and then drives the male rotor of the first screw compression device to rotate through the first synchronous gear set;

[0036] Alternatively, the first active screw is the male rotor of the first screw compression device, and the first driven screw is the female rotor of the first screw compression device; the driving mechanism drives the male rotor of the first screw compression device to rotate, and then drives the female rotor of the first screw compression device to rotate through the first synchronous gear set.

[0037] As an embodiment of the present invention, the second active screw is a male rotor of a second screw compression device, and the second driven screw is a female rotor of the second screw compression device; the first driven gear drives the male rotor of the second screw compression device to rotate, and then drives the female rotor of the second screw compression device to rotate through the second synchronous gear set;

[0038] Alternatively, the second active screw is the female rotor of the second screw compression device, and the second driven screw is the male rotor of the second screw compression device; the first driven gear drives the female rotor of the second screw compression device to rotate, and then drives the male rotor of the second screw compression device to rotate through the second synchronous gear set.

[0039] As an embodiment of the present invention, the third active screw is the male rotor of the third screw compression device, and the third driven screw is the female rotor of the third screw compression device; the second driven gear drives the male rotor of the third screw compression device to rotate, and then drives the female rotor of the third screw compression device to rotate through the third synchronous gear set;

[0040] Alternatively, the third driving screw is the female rotor of the third screw compression device, and the third driven screw is the male rotor of the third screw compression device; the second driven gear drives the female rotor of the third screw compression device to rotate, and then drives the male rotor of the third screw compression device to rotate through the third synchronous gear set.

[0041] As an embodiment of the present invention, the first driving gear is coaxially arranged with the rotation axis of the first driving screw or the rotation axis of the first driven screw, and can rotate along with the first driving screw or the first driven screw.

[0042] As an embodiment of the present invention, the output shaft of the driving mechanism is connected to the first active screw via a coupling; or the driving mechanism and the first active screw are coaxially designed to directly drive the first active screw to operate.

[0043] As an embodiment of the present invention, the oil-free screw compression is a two-stage compressor, and the first screw compression device or the second screw compression device serves as the second-stage screw compression device; a flexible volume ratio slide valve is provided in the casing of the second-stage screw compressor to achieve optimal matching of the exhaust pressure and the required pressure.

[0044] The beneficial effect of the present invention is that the oil-free screw compressor proposed by the present invention can reduce the volume of the equipment and reduce the production cost of the equipment.

[0045] In one application scenario, the present invention employs a drive mechanism to directly drive a first-stage oil-free screw compressor, while a second-stage oil-free screw compressor is driven by a driving gear located on the driving or driven rotor of the first-stage oil-free screw compressor. If desired, the driving gear can simultaneously drive a third-stage oil-free screw compressor, thereby achieving three-stage compression.

[0046] The drive mechanism of the present invention can be driven directly by a high-speed motor or by a conventional speed motor with a speed-increasing gearbox. This patent innovatively proposes the use of a female rotor output shaft drive. Since the female rotor generally has more teeth than the male rotor, the same input speed can achieve a higher design speed for the oil-free screw compressor.

[0047] The present invention uses a driving gear arranged on the driving rotor or the driven rotor of the first-stage oil-free screw compressor for driving. Since the driving rotor or the driven rotor of the first-stage oil-free screw compressor originally has a higher rotational speed, the speed ratio of driving the second-stage screw compressor or the third-stage screw compressor is significantly reduced, the structure of the gear box is simpler, the gear windage loss and the gear meshing loss are significantly reduced, and the noise level is significantly improved.

[0048] The present invention can not only realize a two-stage oil-free screw compressor in a simple and efficient manner, but also provides an innovative solution for a three-stage oil-free screw compressor from a technical perspective. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the structure of an oil-free screw compressor in one embodiment of the present invention.

[0050] Figure 2 Schematic diagram of the structure of an oil-free screw compressor in one embodiment of the present invention.

[0051] Figure 3 Schematic diagram of the structure of an oil-free screw compressor in one embodiment of the present invention.

[0052] Figure 4 Schematic diagram of the structure of an oil-free screw compressor in one embodiment of the present invention.

[0053] Figure 5 Schematic diagram of the structure of a volume ratio adjustable slide valve in one embodiment of the present invention. DETAILED DESCRIPTION

[0054] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0055] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0056] The description in this section is only for several typical embodiments, and the present invention is not limited to the scope of the embodiments described. The same or similar existing technical means and some technical features of the embodiments are mutually replaced within the scope of the description and protection of the present invention.

[0057] The description of the steps in each embodiment in the specification is only for the convenience of explanation, and the implementation method of this application is not limited by the order of implementation of the steps.

[0058] The term "connection" in this specification includes both direct connection and indirect connection. The term "multi-level" in this specification refers to two or more levels.

[0059] The present invention discloses an oil-free screw compressor. Figure 1 This is a schematic diagram of the structure of an oil-free screw compressor in one embodiment of the present invention; Figure 1 The oil-free screw compressor includes: a driving mechanism 4, a first screw compression device 1 (which can be used as a first-stage screw compression device, of course, it can also be used as a second-stage screw compression device, or even a third-stage screw compression device), a second screw compression device 2 (which can be used as a second-stage screw compression device, of course, it can also be used as a first-stage screw compression device, or a third-stage screw compression device) and a transmission component 5. In one embodiment, the oil-free screw compressor only includes two-stage screw compression devices, which is a two-stage oil-free screw compressor (such as Figure 1 、 Figure 2 shown).

[0060] The driving mechanism 4 is connected to the first screw compression device 1 and can drive the first screw compression device 1 to work; the first screw compression device 1 can be connected to the second screw compression device 2 through the transmission assembly 5 and drive the second screw compression device 2 to work.

[0061] The first screw compression device 1 discharges the compressed gas into the second screw compression device 2 , which further compresses the gas.

[0062] The first screw compression device 1 includes a first housing 101, a first driving screw 102, a first driven screw 103 and a first synchronous gear set; the first driving screw 102 and the first driven screw 103 are arranged in the first housing 101; the first synchronous gear set includes a first driving synchronous gear 104 and a first driven synchronous gear 105, and the first driving synchronous gear 104 is meshed with the first driven synchronous gear 105.

[0063] The first active synchronous gear 104 is arranged on the rotation axis of the first active screw 102 and is coaxial with the rotation axis of the first active screw 102 ; the first driven synchronous gear 105 is arranged on the rotation axis of the first driven screw 103 and is coaxial with the rotation axis of the first driven screw 103 .

[0064] The drive mechanism 4 is connected to the first active screw 102 and can drive the first active screw 102 to rotate; the rotation of the first active screw 102 drives the first active synchronous gear 104 to rotate, and the first active synchronous gear 104 drives the first driven synchronous gear 105 to rotate, thereby driving the first driven screw 103 to rotate. When the oil-free screw compressor is in operation, its female and male rotors do not contact each other, and the rotor gap is distributed by the synchronous gear. In one embodiment of the present invention, the output shaft of the drive mechanism 4 is connected to the first active screw 102 via a coupling, or the drive mechanism 4 is coaxial with the first active screw 102 to directly drive the first active screw 102 to operate.

[0065] The second screw compression device 2 includes a second housing 201, a second driving screw 202, a second driven screw 203 and a second synchronous gear set; the second driving screw 202 and the second driven screw 203 are arranged in the second housing 201; the second synchronous gear set includes a second driving synchronous gear 204 and a second driven synchronous gear 205, and the second driving synchronous gear 204 is meshed with the second driven synchronous gear 205.

[0066] The second driving synchronous gear 204 is provided on the rotation axis of the second driving screw 202 and is coaxial with the rotation axis of the second driving screw 202 ; the second driven synchronous gear 205 is provided on the rotation axis of the second driven screw 203 and is coaxial with the rotation axis of the second driven screw 203 .

[0067] The transmission assembly 5 includes a first driving gear 501 and a first driven gear 502. The first driving gear 501 meshes with the first driven gear 502. The first driving gear 501 is mounted on the rotation axis of the first driving screw 102 or the first driven screw 103, while the first driven gear 502 is mounted on the rotation axis of the second driving screw 102. The first driving gear 501 can drive the first driven gear 502 to rotate, thereby driving the second driving screw 102 to rotate. The rotation of the second driving screw 102 drives the second driving synchronous gear 204 to rotate, which in turn drives the second driven synchronous gear 205 to rotate, thereby driving the second driven screw 203 to rotate.

[0068] In one embodiment of the present invention, the first driving gear 501 is coaxially arranged with the rotation axis of the first driving screw 102 or the rotation axis of the first driven screw 103, and can better follow the rotation of the first driving screw 102 or the first driven screw 103 to achieve an optimal design of structure and cost.

[0069] In one embodiment, the first active synchronous gear 104, the first driven synchronous gear 105 and the transmission assembly 5 are arranged in the same gear box 6. With this structural solution, the device structure can be better optimized.

[0070] The first screw compression device 1 is provided with a first air inlet and a first exhaust port, and the second screw compression device 2 is provided with a second air inlet and a second exhaust port; the first exhaust port is connected to the second air inlet via an exhaust channel, and the gas compressed by the first screw compression device 1 is discharged into the second screw compression device 2. The exhaust channel can be an external pipe; the exhaust channel can be integrated with the first shell 101 or can be independent of the first shell 101. In one embodiment, the exhaust channel is provided outside the first shell 101,

[0071] In one embodiment of the present invention, the first active screw 102 is the female rotor of the first screw compression device 1, and the first driven screw 103 is the male rotor of the first screw compression device 1. The drive mechanism 4 drives the female rotor of the first screw compression device 1 to rotate, and then drives the male rotor of the first screw compression device 1 to rotate via the first synchronous gear set. The drive mechanism 4 can be a high-speed motor (e.g., with a speed of 6000 rpm). Because the female rotor has a higher speed than the male rotor, using a high-speed motor connected to the female rotor to drive the first screw compression device 1 can drive the compressor to operate more quickly.

[0072] Of course, the first active screw 102 can also be the male rotor of the first screw compression device 1, and the first driven screw 103 can be the female rotor of the first screw compression device 1; the driving mechanism drives the male rotor of the first screw compression device 1 to rotate, and then drives the female rotor of the first screw compression device 1 to rotate through the first synchronous gear set.

[0073] In one embodiment of the present invention, the second driving screw is the male rotor of the second screw compression device, and the second driven screw is the female rotor of the second screw compression device; the driven gear drives the male rotor of the second screw compression device to rotate, and then drives the female rotor of the second screw compression device to rotate via the second synchronous gear set. Alternatively, the second driving screw is the female rotor of the second screw compression device, and the second driven screw is the male rotor of the second screw compression device; the driven gear drives the female rotor of the second screw compression device to rotate, and then drives the male rotor of the second screw compression device to rotate via the second synchronous gear set.

[0074] Figure 3 、 Figure 4 This is a schematic diagram of the structure of an oil-free screw compressor in one embodiment of the present invention; Figure 3 、 Figure 4 In one embodiment of the present invention, the oil-free screw compressor further includes a third screw compression device 3 (also referred to as a third-stage screw compression device) and a second transmission assembly (the second transmission assembly can be part of the transmission assembly 5); the oil-free screw compressor includes a three-stage screw compression device, which is a three-stage oil-free screw compressor.

[0075] The first screw compression device 1 or the second screw compression device 2 can be connected to the third screw compression device 3 through the second transmission assembly to drive the third screw compression device 3 to work.

[0076] The second screw compression device 2 discharges the compressed gas into the third screw compression device 3 , which further compresses the gas.

[0077] The third screw compression device 3 includes a third housing 301, a third driving screw 302, a third driven screw 303 and a third synchronous gear set; the third driving screw 302 and the third driven screw 303 are arranged in the third housing 301; the third synchronous gear set includes a third driving synchronous gear 304 and a third driven synchronous gear 305, and the third driving synchronous gear 304 is meshed with the third driven synchronous gear 305.

[0078] The third driving synchronous gear 304 is arranged on the rotation axis of the third driving screw 302 and is coaxial with the rotation axis of the third driving screw 302 ; the third driven synchronous gear 305 is arranged on the rotation axis of the third driven screw 303 and is coaxial with the rotation axis of the third driven screw 303 .

[0079] The second transmission assembly includes a second driving gear and a second driven gear 503. The second driving gear meshes with the second driven gear 503. The second driven gear 503 is disposed on the rotation axis of the third driving screw 302. The second driving gear can rotate under the drive of the first driving screw, the first driven screw, the second driving screw, or the second driven screw, thereby driving the second driven gear to rotate, and further driving the third driving screw.

[0080] In one embodiment of the present invention, the first screw compression device 1 is connected to the third screw compression device 3 via a second transmission assembly, thereby driving the third screw compression device 3 to operate. The second driven gear 503 is disposed on the rotation axis of the third driving screw 302; the second driving gear can rotate under the drive of the first driving screw 102 (or the first driven screw 103), thereby driving the second driven gear 503 to rotate, and further driving the third driving screw 302 to operate; the second driving gear of the second transmission assembly is the same component as the driving gear of the transmission assembly; the second transmission assembly can also be used as part of the transmission assembly.

[0081] The rotation of the third driving screw 302 drives the third driving synchronous gear 304 to rotate, and the third driving synchronous gear 304 drives the third driven synchronous gear 305 to rotate, which in turn drives the third driven screw 303 to rotate.

[0082] The third screw compression device 3 is provided with a third air inlet and a third exhaust port; the second exhaust port is connected to the third air inlet via a second exhaust channel, and the gas compressed by the second screw compression device 2 is discharged into the third screw compression device 3.

[0083] In addition, the male and female rotors of the first screw compression device 1 are provided with sealing mechanisms 106, 107, 111, 112 (such as sealing rings) and bearings 108, 109, 113, 114 at both ends, respectively. The sealing mechanisms 106, 107, 111, 112 are respectively arranged on the inner sides of the bearings 108, 109, 113, 114, i.e., closer to the rotor body. A shaft sealing mechanism 110 may also be provided at the connection end between the first active screw and the high-speed motor. The male and female rotors of the second screw compression device 2 are provided with sealing mechanisms 206, 207, 210, 211 (such as sealing rings) and bearings 208, 209, 212, 213 at both ends, respectively. The sealing mechanisms 206, 207, 210, 211 are respectively arranged on the inner sides of the bearings 208, 209, 212, 213, i.e., closer to the rotor body. The two ends of the male rotor and the female rotor of the third screw compression device 3 are respectively provided with sealing mechanisms 306, 307, 310, 311 (such as sealing rings) and bearings 308, 309, 312, 313; the sealing mechanisms 306, 307, 310, 311 are arranged on the inner side of the bearings 308, 309, 312, 313, that is, close to the side of the rotor body.

[0084] The sealing mechanisms 106, 107, 111, 112 and bearings 108, 109, 113, 114 can be set in the first housing 101, and the sealing mechanisms 206, 207, 210, 211 and bearings 208, 209, 212, 213 can be set in the second housing 201; the first driving synchronous gear 104, the first driven synchronous gear 105, the driving gear 501, the driven gear 502 and the second driven gear 503 are set in the gear box 6.

[0085] In addition, the present invention may also be provided with more stages of screw compression devices; and each stage of the screw compression device may include one screw compression device or multiple screw compression devices.

[0086] In one embodiment of the present invention, the shell of the last-stage screw compression device (i.e., the second-stage screw compression device of a two-stage oil-free screw compressor or the third-stage screw compression device of a three-stage oil-free screw compressor) can be provided with a volume ratio adjustable sliding valve to achieve optimal matching of the exhaust pressure and the user pressure.

[0087] For example, the oil-free screw compressor is a two-stage compressor, and the second screw compression device serves as the second-stage screw compression device; a flexible volume ratio slide valve is set on the shell of the second-stage screw compressor to achieve optimal matching of exhaust pressure and demand pressure.

[0088] For another example, the oil-free screw compressor is a three-stage compressor, and the third screw compression device serves as the third-stage screw compression device; a flexible volume ratio slide valve is provided in the casing of the third-stage screw compressor to achieve optimal matching of exhaust pressure and demand pressure.

[0089] Figure 5 This is a schematic diagram of the structure of a volume ratio adjustable slide valve in one embodiment of the present invention; Figure 5In one embodiment, the volume ratio adjustable slide valve 7 includes a housing 700, a slide valve body 701, a first cylinder 702, a second cylinder 703, a first piston 704, a second piston 705, a first medium channel 706, a second medium channel 707, and an elastic mechanism 708. The slide valve body 701, the first cylinder 702, and the second cylinder 703 are arranged on the housing 700, with the slide valve body 701 disposed between the first cylinder 702 and the second cylinder 703. A first piston 704 and a second piston 705 are disposed at either end of the slide valve body 701, respectively. The first piston 704 is disposed within the first cylinder 702 and can move in a set direction within the first cylinder 702. The second piston 705 is disposed within the second cylinder 703 and can move in a set direction within the second cylinder 703. The elastic mechanism 708 is disposed between the second piston 705 and the end of the second cylinder 703. A first sealing mechanism 709 is provided at the contact point between the first piston 704 and the first cylinder 702, and a second sealing mechanism 710 is provided at the contact point between the second piston 705 and the second cylinder 703. A self-lubricating coating 711 is provided at the contact surface between the first cylinder 702 and the first piston 704, and a self-lubricating coating 712 is provided at the contact surface between the second cylinder 703 and the second piston 705. Furthermore, a self-lubricating coating 713 may also be provided at the contact point between the spool valve body 701 and the housing 700. The spool valve body 701 is provided with a first medium channel 706 and a second medium channel 707. The first medium channel 706 is connected to the first cylinder 702, and the second medium channel 707 is connected to the second cylinder 703. The position of the spool valve body 701 can be controlled by controlling the flow of gas into the first cylinder 702 or the second cylinder 703.

[0090] In summary, the oil-free screw compressor proposed in the present invention can reduce the size of the equipment and lower the production cost of the equipment.

[0091] In one application scenario, the present invention employs a drive mechanism to directly drive a first-stage oil-free screw compressor, while a second-stage oil-free screw compressor is driven by a driving gear located on the driving or driven rotor of the first-stage oil-free screw compressor. If desired, the driving gear can simultaneously drive a third-stage oil-free screw compressor, thereby achieving three-stage compression.

[0092] The drive mechanism of the present invention can be driven directly by a high-speed motor or by a conventional speed motor with a speed-increasing gearbox. This patent innovatively proposes the use of a female rotor output shaft drive. Since the female rotor generally has more teeth than the male rotor, the same input speed can achieve a higher design speed for the oil-free screw compressor.

[0093] The present invention uses a driving gear arranged on the driving rotor or the driven rotor of the first-stage oil-free screw compressor for driving. Since the driving rotor or the driven rotor of the first-stage oil-free screw compressor originally has a higher rotational speed, the speed ratio of driving the second-stage screw compressor or the third-stage screw compressor is significantly reduced, the structure of the gear box is simpler, the gear windage loss and the gear meshing loss are significantly reduced, and the noise level is significantly improved.

[0094] The present invention can not only realize a two-stage oil-free screw compressor in a simple and efficient manner, but also provides an innovative solution for a three-stage oil-free screw compressor from a technical perspective.

[0095] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The description and application of the present invention here are illustrative and are not intended to limit the scope of the present invention to the above-described embodiments. The effects or advantages involved in the embodiments may not be embodied in the embodiments due to interference from various factors, and the description of the effects or advantages is not used to limit the embodiments. Variations and changes to the embodiments disclosed here are possible, and the replacement of the embodiments and various equivalent components are well known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials, and parts without departing from the spirit or essential characteristics of the present invention. Other variations and changes can be made to the embodiments disclosed here without departing from the scope and spirit of the present invention.

Claims

1. An oil-free screw compressor, characterized in that: The oil-free screw compressor comprises: a driving mechanism, a first screw compression device, a second screw compression device and a first transmission assembly; The driving mechanism is connected to the first screw compression device to drive the first screw compression device to work; the first screw compression device is connected to the second screw compression device through the first transmission assembly to drive the second screw compression device to work; The first screw compression device discharges the compressed gas into the second screw compression device, which further compresses the gas. The first screw compression device includes a first housing, a first driving screw, a first driven screw and a first synchronous gear set; the first driving screw and the first driven screw are disposed in the first housing; the first synchronous gear set includes a first driving synchronous gear and a first driven synchronous gear, the first driving synchronous gear meshing with the first driven synchronous gear; The first active synchronous gear is provided on the rotation axis of the first active screw and is coaxial with the rotation axis of the first active screw; the first driven synchronous gear is provided on the rotation axis of the first driven screw and is coaxial with the rotation axis of the first driven screw; The driving mechanism is connected to the first active screw to drive the first active screw to rotate; the rotation of the first active screw drives the first active synchronous gear to rotate, and the first active synchronous gear drives the first driven synchronous gear to rotate, thereby driving the first driven screw to rotate; The second screw compression device includes a second housing, a second driving screw, a second driven screw and a second synchronous gear set; the second driving screw and the second driven screw are disposed in the second housing; the second synchronous gear set includes a second driving synchronous gear and a second driven synchronous gear, and the second driving synchronous gear is meshed with the second driven synchronous gear; The second driving synchronous gear is provided on the rotation axis of the second driving screw and is coaxial with the rotation axis of the second driving screw; the second driven synchronous gear is provided on the rotation axis of the second driven screw and is coaxial with the rotation axis of the second driven screw; The first transmission assembly includes a first driving gear and a first driven gear, wherein the first driving gear is meshed with the first driven gear; The first driving gear is arranged on the rotation axis of the first driving screw or the first driven screw, and the first driven gear is arranged on the rotation axis of the second driving screw; the first driving gear can drive the first driven gear to rotate, thereby driving the second driving screw to rotate; the rotation of the second driving screw drives the second driving synchronous gear to rotate, and the second driving synchronous gear drives the second driven synchronous gear to rotate, thereby driving the second driven screw to rotate.

2. The oil-free screw compressor according to claim 1, characterized in that: The first screw compression device is provided with a first air inlet and a first air outlet, and the second screw compression device is provided with a second air inlet and a second air outlet; The first exhaust port of the first screw compression device is connected to the second air inlet through an exhaust channel, so that the gas compressed by the first screw compression device is discharged into the second screw compression device.

3. The oil-free screw compressor according to claim 1, characterized in that: The first driving synchronous gear, the first driven synchronous gear and the first transmission assembly are arranged in the same gear box.

4. The oil-free screw compressor according to claim 1, characterized in that: The first active screw is the female rotor of the first screw compression device, and the first driven screw is the male rotor of the first screw compression device; the driving mechanism drives the female rotor of the first screw compression device to rotate, and then drives the male rotor of the first screw compression device to rotate through the first synchronous gear set; Alternatively, the first active screw is the male rotor of the first screw compression device, and the first driven screw is the female rotor of the first screw compression device; the driving mechanism drives the male rotor of the first screw compression device to rotate, and then drives the female rotor of the first screw compression device to rotate through the first synchronous gear set.

5. The oil-free screw compressor according to claim 1, characterized in that: The second active screw is the male rotor of the second screw compression device, and the second driven screw is the female rotor of the second screw compression device; the first driven gear drives the male rotor of the second screw compression device to rotate, and then drives the female rotor of the second screw compression device to rotate through the second synchronous gear set; Alternatively, the second active screw is the female rotor of the second screw compression device, and the second driven screw is the male rotor of the second screw compression device; the first driven gear drives the female rotor of the second screw compression device to rotate, and then drives the male rotor of the second screw compression device to rotate through the second synchronous gear set.

6. The oil-free screw compressor according to claim 1, characterized in that: The first driving gear is coaxially arranged with the rotation axis of the first driving screw or the rotation axis of the first driven screw, and can rotate along with the first driving screw or the first driven screw.

7. The oil-free screw compressor according to claim 1, characterized in that: The output shaft of the driving mechanism is connected to the first active screw through a coupling; or the driving mechanism and the first active screw are coaxially designed to directly drive the first active screw to operate.

8. The oil-free screw compressor according to claim 1, characterized in that: The oil-free screw compressor is a two-stage compressor, with the first screw compression device or the second screw compression device serving as the second-stage screw compression device; a flexible volume ratio slide valve is provided on the housing of the second-stage screw compressor to achieve optimal matching of exhaust pressure and demand pressure.

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