Oil-free screw air compressor

Abstract

This invention discloses an oil-free screw air compressor, belonging to the field of air compressor technology. It includes a casing and an intake air filter system above it. The casing integrates an intake regulating component, a primary compression system, a primary cooling component, a two-stage compression system, a secondary cooling component, a tertiary exhaust component, a water cooling system, an oil cooling circulation system, an oil mist extraction component, an electrical control system, and inlet and outlet silencers. The intake air filter system features a labyrinthine air duct to absorb high-frequency noise. The tertiary exhaust component includes a venturi tube and an expanded perforated plate silencer to achieve stable flow and wide-frequency noise reduction. The oil cooling circulation system, centered on a storage oil tank, forms a closed-loop cycle of gravity recirculation and pressure supply, providing centralized lubrication and cooling for each stage of the gearbox. The inlet and outlet silencers are both plate-type resistive structures, adapting to high-flow noise reduction requirements. This invention, through optimized spatial layout and multiple noise reduction designs, significantly reduces overall machine noise while achieving a wide range of exhaust volumes, ensuring stable and reliable operation.

Description

Technical Field

[0001] This invention relates to the field of air compressor technology, and more specifically to an oil-free screw air compressor. Background Technology

[0002] An oil-free screw air compressor is a special type of air compressor that compresses gas through the meshing of a screw rotor without requiring the injection of lubricating oil into the compression chamber during the compression process. Because the compressed air it discharges is 100% oil-free, it effectively avoids contamination of end-use equipment by lubricating oil. Therefore, oil-free screw air compressors are widely used in industries such as pharmaceutical manufacturing, food processing, electronic component production, textile printing and dyeing, and precision instruments, especially in clean production environments with extremely stringent air quality requirements, where they hold an irreplaceable position. Compared to traditional oil-injected screw air compressors, oil-free screw air compressors eliminate the need for oil separator replacement, oil management, and oil mist contamination, significantly reducing the burden on downstream purification equipment and improving air safety.

[0003] However, existing oil-free screw air compressors still have the following technical limitations and development bottlenecks:

[0004] First, the displacement is generally small, making it difficult to meet the needs of large-volume air consumption scenarios. Because oil-free screw compressors require minute gaps between rotors and between the rotor and the housing to avoid contact friction, and cannot rely on lubricating oil for sealing, their volumetric efficiency is lower than that of oil-injected models. Furthermore, the lack of oil cooling during compression results in a higher temperature rise in the compression chamber, limiting the improvement of the compression ratio. Therefore, currently, mature oil-free screw air compressor products on the market are still mainly small to medium displacement (typically not exceeding 80 m³). 3 The existing oil-free screw compressors are mainly designed for decentralized or small-to-medium-scale gas consumption scenarios. However, for large pharmaceutical bases, electronics industrial parks, food processing centers, and other scenarios that require centralized gas supply, large gas consumption, and continuous and stable gas consumption, existing oil-free screw compressors are difficult to meet their gas consumption needs. They often have to adopt multiple parallel or directional oil-injected compressors for after-treatment, which increases the complexity of the system and the operating cost.

[0005] Larger capacity compressors mean larger compressor units, heavier cooling system loads, and thicker piping. If the spatial layout of the system components within the chassis is not optimized, it can easily lead to long piping, too many bends, and increased pressure loss. This also encroaches on maintenance space and increases the difficulty of daily maintenance and troubleshooting. Some existing high-power oilless screw compressors fail to balance performance and maintainability in their structural design, resulting in problems such as inconvenient cooler cleaning, complex oil piping, and poor heat dissipation in the electrical control cabinet.

[0006] Secondly, noise control becomes significantly more challenging with high-volume oil-free screw air compressors. As the discharge volume increases, the mechanical, aerodynamic, and electromagnetic noise of the compressor itself, as well as the motor's electromagnetic noise, all increase accordingly. Particularly in three-stage compression systems, the high-pressure gas flows at high speed through each stage's exhaust ports and pipes, easily generating broadband airflow noise, with high-frequency noise being particularly prominent. While variable frequency speed control technology helps with energy saving, the airflow pulsations caused by speed changes complicate the noise spectrum, making it difficult for traditional single-structure silencers to effectively reduce noise across the entire frequency range and speed range. Existing products still have shortcomings in the acoustic treatment of the intake, exhaust ports, and the overall casing, making it difficult to meet increasingly stringent occupational health and environmental noise standards.

[0007] Third, the stability requirements for the lubrication and cooling systems are higher. Existing oilless screw air compressors often use independent oil supply to each compression unit for gearbox lubrication, resulting in complex systems with dispersed oil circuits, which is not conducive to centralized management and maintenance. Furthermore, for three-stage compression models with large air volume, the gearbox experiences high heat loads. Improper oil circuit design can easily lead to localized high temperatures and poor lubrication, affecting the lifespan of bearings and gears. Achieving centralized oil supply, efficient cooling, and stable circulation is one of the key issues in improving the overall reliability of the machine. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an oil-free screw air compressor that overcomes the deficiencies of existing technologies. By optimizing the spatial layout and implementing multiple noise reduction designs, it significantly reduces the overall noise of the machine while achieving a wide range of exhaust volumes, ensuring stable and reliable operation.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] An oil-free screw air compressor includes a casing. An intake air filter system is fixedly installed on the top of the casing. Inside the casing, an intake regulating component, a primary compression system, a primary cooling component, a two-stage compression system, a secondary cooling component, a tertiary exhaust component, a water cooling system, and an oil cooling circulation system are fixedly installed. The intake regulating component is connected to the intake air filter system via a pipeline. The intake port of the primary compression system is connected to the outlet port of the intake regulating component, and the intake port of the primary cooling component is connected to the exhaust port of the primary compression system.

[0011] The two-stage compression system includes a two-stage compressor main unit and a two-stage drive motor that drives the two-stage compressor main unit; the two-stage compressor main unit has a second-stage air inlet, a third-stage air inlet and a third-stage exhaust port, and the second-stage air inlet is connected to the exhaust port of the first-stage cooling component;

[0012] The air inlet of the secondary cooling component is connected to the secondary exhaust port of the two-stage compressor, and the exhaust port of the secondary cooling component is connected to the tertiary air inlet of the two-stage compressor; the air inlet of the tertiary exhaust component is connected to the tertiary exhaust port of the two-stage compressor, and the exhaust port of the tertiary exhaust component is used to output clean high-pressure gas after three-stage compression and precision cooling to the outside.

[0013] The water cooling system is used to cool the drive motors of the primary compression system and the secondary compression system; the oil cooling circulation system is used to continuously provide lubricating oil for cooling the primary compression system and the secondary compression system.

[0014] Preferably, the primary cooling assembly is arranged below the dual-stage drive motor; the secondary cooling assembly is arranged below the dual-stage compressor; and both the water cooling system and the oil cooling circulation system are arranged above the primary cooling assembly.

[0015] Preferably, the air intake air filter system includes an air filter housing and a labyrinthine air duct disposed therein. The air outlet of the air filter housing is connected to the air intake regulating component via a rubber hose. An air filter is disposed inside the air filter housing, and the labyrinthine air duct is located on the airflow channel between the air filter and the air outlet of the air filter housing. The labyrinthine air duct is composed of multiple staggered sound-absorbing baffles, forming a tortuous labyrinthine airflow path within the airflow channel.

[0016] The sound-absorbing baffle is a sound-absorbing structure made of multi-layer composite material, used to reflect and absorb high-frequency noise that propagates in reverse from the primary compression system and the secondary compression system to the intake air filter system multiple times.

[0017] Preferably, the three-stage exhaust assembly includes a venturi tube and an expanded perforated plate muffler; the intake end of the venturi tube is sealed to the three-stage exhaust port, and the exhaust side of the venturi tube is connected to the expanded perforated plate muffler.

[0018] The expansion-type perforated plate silencer includes an expansion chamber and a perforated plate. The expansion chamber is a closed cavity used to receive gas after it has been processed by a venturi tube and to eliminate low-frequency noise in the airflow. The perforated plate is fixedly installed on the outlet side of the expansion chamber and has multiple through-holes for eliminating high-frequency noise in the compressed gas.

[0019] Preferably, the oil cooling circulation system includes a storage oil tank and an oil pump. The oil inlet of the storage oil tank is connected to the gearbox outlet of the primary compression system and the gearbox outlet of the secondary compression system, respectively. The oil outlet of the storage oil tank is connected to the oil inlet of the oil pump, and the oil outlet of the oil pump is sealed to the oil inlet of the oil cooler. The oil outlet of the oil cooler is connected to the gearbox lubrication inlet of the primary compression system and the gearbox lubricating oil inlet of the secondary compression system via an oil supply pipeline.

[0020] The oil inlet of the storage tank is positioned vertically lower than the gearbox outlet of the primary compression system and the gearbox outlet of the secondary compression system, so that the high-temperature hydraulic oil flows into the storage tank by gravity.

[0021] Preferably, it further includes a compressor main unit oil mist extraction assembly disposed inside the air compressor housing. The compressor main unit oil mist extraction assembly includes a filter box and a fan. The air inlet of the filter box is connected to the oil mist port of the gearbox of the first-stage compression system and the gearbox of the two-stage compression system respectively through pipelines. The air outlet of the filter box is sealed to the air inlet of the fan. An air filter assembly is fixedly installed at the front end of the air inlet of the fan. The fan is used to extract oil mist-containing gas from the gearboxes of the first-stage compression system and the two-stage compression system through the filter box, so that a negative pressure state is formed inside each gearbox.

[0022] Preferably, it also includes an inlet silencer and an outlet silencer, wherein the inlet silencer is located on the air intake side of the air compressor housing and is connected to the internal airflow channel of the air compressor housing; the outlet silencer is located on the exhaust side of the air compressor housing.

[0023] Both the inlet muffler and the outlet muffler are plate-type resistive mufflers; the cross-sectional area of ​​the airflow channel of the inlet muffler is matched with the airflow rate of the air intake air filter system, and the cross-sectional area of ​​the airflow channel of the outlet muffler is matched with the exhaust flow rate of the three-stage exhaust assembly.

[0024] Preferably, the water cooling system includes a water pump, a water tank, a heat exchanger, a first cooling branch, a second cooling branch, and a third cooling branch; the inlet of the water pump is connected to the outlet of the water tank, the inlet of the heat exchanger is connected to the outlet of the water pump, and the outlet of the heat exchanger is connected to the water tank, forming a main cooling loop; the first cooling branch is connected between the outlet of the water pump and the cooling channel of the first-stage drive motor of the first-stage compression system, for cooling the first-stage drive motor; the second cooling branch is connected between the outlet of the water pump and the cooling channel of the second-stage drive motor of the second-stage compression system, for cooling the second-stage drive motor; the third cooling branch is connected between the outlet of the water pump and the cooling channel of the integrated frequency converter, for cooling the integrated frequency converter; the integrated frequency converter provides adjustable frequency drive signals for the first-stage drive motor and the second-stage drive motor.

[0025] Preferably, it also includes an electrical control system, which is installed inside the chassis and configured to execute pre-lubrication and pre-cooling control logic, specifically including:

[0026] The electrical control system responds to the air compressor start command by sending a pre-start signal to the oil pump of the oil cooling circulation system and the water pump of the water cooling system before sending the main start signal to the primary compression system and the secondary compression system.

[0027] In response to the pre-start signal, the oil pump draws hydraulic oil from the storage tank, cools it in the oil cooler, and then delivers it to the gearboxes of the primary compression system and the secondary compression system to pre-lubricate the gears and bearings.

[0028] The water pump responds to the pre-start signal and drives the coolant to circulate in the water cooling system to pre-cool the drive motor of the first-stage compression system, the drive motor of the second-stage compression system, and the corresponding integrated frequency converter.

[0029] After the oil pump and the water pump have been running for a preset time or under preset conditions, the electrical control system sends a main unit start signal to the primary compression system and the secondary compression system.

[0030] Preferably, the intake regulating component includes a butterfly valve, the valve plate of which is configured to maintain a slightly open state at a preset angle when the air compressor is in a stopped or standby state.

[0031] This invention provides an oil-free screw air compressor. It has the following beneficial effects:

[0032] By optimizing the layout of the various functional modules inside the chassis, a highly integrated three-dimensional structure is formed. This allows for coverage of a wide range of exhaust volumes while significantly shortening the connecting pipes between components, reducing airflow resistance and pressure loss, and lowering the risk of pipe leaks. It also makes full use of unused space under the motor and main unit, resulting in a more compact overall structure that facilitates transportation and installation. Furthermore, it provides easily accessible operating space for components requiring regular maintenance, such as the cooler, filter, and oil pump, making daily maintenance and troubleshooting more convenient and effectively reducing the total life-cycle cost of the equipment.

[0033] By constructing a comprehensive, multi-stage noise reduction system from the intake to the exhaust end, the noise control level of the large-volume oil-free screw air compressor has been significantly improved, solving the technical challenge of existing technologies struggling to cope with wideband noise and noise fluctuations under variable frequency conditions. At the intake end, a labyrinthine air duct is installed inside the intake air filter system, forming a tortuous labyrinthine path within the airflow channel. This allows for multiple reflections and effective absorption of high-frequency noise propagating backward from the compressor to the intake port without increasing intake resistance, significantly reducing noise radiated from the intake port. At the exhaust end, the three-stage exhaust assembly adopts a combination structure of a Venturi tube and an expanding perforated plate silencer. The Venturi tube guides and rectifyes the high-speed airflow ejected from the three-stage exhaust port, reducing turbulent noise generated by airflow shearing. Simultaneously, the expanding section converts kinetic energy into pressure energy, reducing the outlet velocity and reducing aerodynamic noise at its source. The expansion-type perforated plate silencer employs a unique structure consisting of an expansion chamber followed by a perforated plate. This combination forms a complete silencing chain, allowing the noise reduction spectrum to cover a wider frequency range. This effectively addresses the noise spectrum drift caused by speed changes due to variable frequency drive, ensuring the air compressor maintains excellent noise reduction performance across its entire speed range. Furthermore, by incorporating plate-type resistive inlet and outlet silencers, the airflow channel cross-sectional area is matched to high-flow-rate conditions, effectively absorbing mid-to-high-frequency noise in the airflow while avoiding additional pressure loss.

[0034] By designing a dynamic oil cooling circulation system centered on a reserve oil tank, a stable and reliable lubrication and cooling solution is provided for the gearboxes of multi-stage compressors. Through a closed-loop circulation system of "gravity return oil - pressure supply oil," the reserve oil tank is positioned below each gearbox, allowing high-temperature hydraulic oil to automatically return by gravity without additional power, resulting in energy savings and reliability. The oil is then drawn by an oil pump and forced into an oil cooler for cooling, ensuring that the lubricating oil temperature entering the gearbox remains within a suitable range, guaranteeing lubrication effectiveness. The reserve oil tank also serves as an oil storage and buffer, preventing cavitation caused by the oil pump directly drawing in high-temperature return oil, thus improving the operational stability of the oil circuit system. Furthermore, the gearboxes of each stage of the compressor share the same oil pump and oil cooler, simplifying the oil circuit structure and reducing system complexity. The circulation loop design also allows for the reuse of hydraulic oil, reducing oil costs.

[0035] The butterfly valve's valve plate remains slightly open at a preset angle when the compressor is stopped or in standby mode. This allows the compressor to quickly establish initial internal pressure during startup, providing the actuator with the necessary power for a smooth start and preventing airflow impact caused by sudden valve plate opening. The compressor's oil mist extraction assembly continuously draws oil-mist gas from each gearbox, maintaining a slight negative pressure inside the gearboxes. This effectively prevents hydraulic oil from entering the compression chamber through gaps such as shaft seals, fundamentally ensuring the oil-free quality of the output gas. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the prior art will be briefly introduced below.

[0037] Figure 1 A schematic diagram of the overall system structure of an oil-free screw air compressor according to the present invention;

[0038] Figure 2 A schematic diagram of the intake regulating component of an oil-free screw air compressor according to the present invention;

[0039] Figure 3 Structural diagram of the intake air filter system in this embodiment of the invention;

[0040] Figure 4 A schematic diagram of the structure of the labyrinth-type air duct sound-absorbing baffle in an embodiment of the present invention;

[0041] Figure 5 A schematic diagram of the structure of the primary compression system in this embodiment of the invention;

[0042] Figure 6 A schematic diagram of the two-stage compression system in this embodiment of the invention;

[0043] Figure 7 A schematic diagram of the three-stage exhaust assembly system in an embodiment of the present invention;

[0044] Figure 8 Schematic diagram of the expanded perforated plate silencer in an embodiment of the present invention;

[0045] Figure 9 A schematic diagram of the water cooling system structure in an embodiment of the present invention;

[0046] Figure 10 A schematic diagram of the oil cooling circulation system in this embodiment of the invention;

[0047] Figure 11 A schematic diagram of the oil mist extraction assembly of the compressor host in this embodiment of the invention;

[0048] Figure 12 A schematic diagram showing the installation positions of the inlet and outlet silencers in an embodiment of the present invention;

[0049] Figure 13 A schematic diagram of the internal structure of the inlet muffler and the outlet muffler in an embodiment of the present invention;

[0050] Figure 14 A schematic diagram of the spatial layout of the hydraulic oil circulation system and the water circulation system in an embodiment of the present invention;

[0051] Explanation of the labels in the diagram:

[0052] 1. Chassis; 2. Intake air filter system; 3. Intake regulating assembly; 4. First-stage compression system; 5. First-stage cooling assembly; 6. Two-stage compression system; 7. Second-stage cooling assembly; 8. Third-stage exhaust assembly; 9. Water cooling system; 10. Oil cooling circulation system; 11. Compression unit oil mist extraction assembly; 12. Electrical control system; 13. Inlet silencer; 14. Outlet silencer;

[0053] 21. Air filter; 22. Air filter housing; 23. Labyrinth duct; 31. Rubber hose; 32. Butterfly valve; 33. Butterfly valve upper connection; 34. Butterfly valve lower connection; 41. First-stage compressor; 42. First-stage drive motor; 43. Coupling; 44. Integrated support base; 61. Two-stage compressor; 62. Two-stage drive motor; 63. Coupling; 64. Two-stage integrated support base; 611. Second-stage air inlet; 612. Second-stage exhaust port; 613. Third-stage air inlet... Air inlet; 614, three-stage exhaust port; 81, venturi tube; 82, connecting pipe; 83, expansion type perforated plate silencer; 84, transition pipe; 85, check valve; 86, exhaust pipe; 831, expansion chamber; 832, perforated plate; 91, water pump; 92, water tank; 93, heat exchanger; 94, cooling pipeline; 101, oil storage tank; 102, oil pump; 103, oil cooler; 104, oil supply pipeline; 111, filter box; 112, fan; 113, air filter assembly. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0055] Example 1, as Figures 1 to 14 As shown, an oil-free screw air compressor includes a casing 1. An intake air filter system 2 is fixedly installed on the top of the casing 1. Inside the casing 1, an intake regulating assembly 3, a primary compression system 4, a primary cooling assembly 5, a two-stage compression system 6, a secondary cooling assembly 7, a tertiary exhaust assembly 8, a water cooling system 9, an oil cooling circulation system 10, a compressor main unit oil mist extraction assembly 11, and an electrical control system 12 are fixedly installed.

[0056] The intake regulating component 3 is connected to the intake air filter system 2 via a pipeline; the intake port of the first-stage compression system 4 is connected to the outlet port of the intake regulating component 3, and the intake port of the first-stage cooling component 5 is connected to the exhaust port of the first-stage compression system 4.

[0057] The two-stage compression system 6 includes a two-stage compression host 61 and a two-stage drive motor 62 that drives the two-stage compression host 61; the two-stage compression host 61 has a second-stage air inlet 611, a third-stage air inlet 613 and a third-stage exhaust port 614, and the second-stage air inlet 611 is connected to the exhaust port of the first-stage cooling component 5.

[0058] The air inlet of the secondary cooling component 7 is connected to the secondary exhaust port 612 of the two-stage compressor host 61, and the exhaust port of the secondary cooling component 7 is connected to the tertiary air inlet 613 of the two-stage compressor host 61; the air inlet of the tertiary exhaust component 8 is connected to the tertiary exhaust port 614 of the two-stage compressor host 61, and the exhaust port of the tertiary exhaust component 8 is used to output clean high-pressure gas after three-stage compression and precision cooling to the outside.

[0059] The water cooling system 9 is used to cool the drive motors of the primary compression system 4 and the secondary compression system 6; the oil cooling circulation system 10 is used to continuously provide lubricating oil for cooling the primary compression system 4 and the secondary compression system 6.

[0060] This embodiment features an optimized spatial layout to balance the need for large volume of cargo with ease of transportation, assembly, and maintenance. Specifically:

[0061] The primary cooling component 5 is located below the dual-stage drive motor 62 of the dual-stage compression system 6, making full use of the unused space below the dual-stage drive motor 62, while shortening the pipeline connection distance between it and the primary compression system 4.

[0062] The secondary cooling assembly 7 is arranged below the two-stage compressor host 61 of the two-stage compression system 6, so as to minimize the pipeline between the secondary exhaust port and the cooler inlet and reduce pressure loss;

[0063] Both the water cooling system 9 and the oil cooling circulation system 10 are arranged above the primary cooling component 5, forming an upper and lower stacked structure, which effectively reduces the footprint of the entire machine.

[0064] The electrical control system 12 is located to the left of the primary drive motor 42 of the primary compression system 4, away from the high-temperature area and convenient for operators to set parameters and troubleshoot faults.

[0065] This layout minimizes the connection paths of gas, oil, and water pipelines between system components, reducing pressure loss and potential leaks. It also provides easily accessible maintenance spaces and interfaces for components requiring regular maintenance, such as coolers, oil filters, and air filters, facilitating daily inspection, maintenance, and component replacement. Thus, while meeting the requirements for high-volume compression, it comprehensively considers transportation size limitations, manufacturing costs, assembly processability, and ease of daily maintenance, resulting in a highly integrated, unified structure.

[0066] In Example 2, as a further preferred embodiment of Example 1, the air intake air filter system 2 includes an air filter housing 22 and a labyrinthine air duct 23 disposed within it. The air filter housing 22 is a sealed housing structure with an openable door on one side for easy replacement of the filter element of the internal air filter 21. The air inlet of the air filter housing 22 is connected to the outside atmosphere, and the air outlet of the air filter housing 22 is sealed to the air intake pipe of the air intake regulating assembly 3 via a rubber hose 31.

[0067] An air filter 21 is installed inside the air filter housing 22. A labyrinthine air duct 23 is located in the airflow channel between the air filter 21 and the air outlet of the air filter housing 22. The labyrinthine air duct 23 is composed of multiple staggered sound-absorbing baffles, forming a tortuous labyrinthine airflow path within the airflow channel, causing the airflow to change direction at least twice during its flow. The sound-absorbing baffles are sound-absorbing structures made of multi-layer composite materials. When the airflow passes through the labyrinthine air duct 23, the high-frequency noise propagating in the reverse direction from the primary compression system 4 and the secondary compression system 6 to the intake air filter system 2 is reflected multiple times in the tortuous labyrinthine airflow path and effectively absorbed by the sound-absorbing baffle material, thereby significantly reducing the noise radiated outward from the air inlet.

[0068] In this embodiment, the flow cross-sectional area of ​​the labyrinthine air duct 23 is based on the maximum exhaust volume of 230m³. 3 The design is based on a speed of / min to ensure efficient noise reduction without generating excessive intake resistance. The arrangement density and spacing of the noise-reducing baffles are optimized according to the target noise reduction frequency band, with a focus on absorbing high-frequency noise in the 1000Hz-8000Hz range.

[0069] Example 3, as a further preferred embodiment of Example 1, such as Figure 1 and Figure 2 As shown, the intake regulating assembly 3 includes a rubber hose 31, a butterfly valve 32, an upper butterfly valve connector 33, and a lower butterfly valve connector 34. One end of the rubber hose 31 is connected to the outlet of the intake air filter system 2, and the other end is connected to the upper butterfly valve connector 33. The butterfly valve 32 is installed between the upper butterfly valve connector 33 and the lower butterfly valve connector 34, and the lower butterfly valve connector 34 is connected to the intake port of the primary compression system 4. The butterfly valve 32 is an electrically or pneumatically controlled actuator, controlled by the electrical control system 12. By adjusting the opening angle of the valve plate, it controls the airflow entering the primary compression system 4 to coordinate with the loading and unloading operations of the air compressor, thereby achieving dynamic adjustment of the exhaust volume.

[0070] Furthermore, this embodiment features a special design for the initial state of the butterfly valve 32. When the air compressor is in a stopped or standby state, the valve plate of the butterfly valve 32 is not completely closed, but rather maintains a slightly open state at a preset angle. This slightly open state is typically 5% to 15% of the maximum opening of the butterfly valve 32, preferably 3° to 10°. The purpose of this design is to allow a limited amount of airflow to enter the primary compression system 4 through the intake regulating component 3 during the initial startup of the air compressor, assisting the primary compression system 4 in quickly establishing its initial internal pressure. This initial internal pressure can serve as a power source, driving the actuator of the butterfly valve 32 (such as a pneumatic actuator or an electric actuator) to smoothly open the valve plate to its normal operating opening, avoiding the shock and surge that may occur from a sudden opening from a fully closed state. Moreover, the slightly open state limits the intake volume at the moment of startup, effectively reducing the initial load on the compressor and facilitating a smooth motor startup.

[0071] Example 4, as a further preferred embodiment of Example 1, such as Figure 1 , Figure 2 , Figure 5 and Figure 6 As shown, the three-stage compression system in this embodiment consists of a single-stage compression system 4 and a two-stage compression system 6.

[0072] The primary compression system 4 includes a primary compression unit 41, a primary drive motor 42, a coupling 43, and an integrated support base 44. The primary drive motor 42 is connected to the rotor shaft of the primary compression unit 41 via the coupling 43. The primary compression unit 41 and the primary drive motor 42 are fixedly mounted on the integrated support base 44 to ensure coaxiality and operational stability.

[0073] The two-stage compression system 6 includes a two-stage compressor main unit 61, a two-stage drive motor 62, a coupling 63, and a two-stage integrated support base 64. The two-stage compressor main unit 61 is an integrated structure, internally integrating a two-stage compression rotor and a three-stage compression rotor, driven by the same main shaft, enabling two-stage and three-stage compression of gas. The two-stage drive motor 62 is connected to the main shaft of the two-stage compressor main unit 61 via the coupling 63. The two-stage drive motor 62 and the two-stage compressor main unit 61 are jointly and fixedly mounted on the two-stage integrated support base 64.

[0074] The gas flow path is as follows:

[0075] S201: After being purified by the intake air filter system 2, the ambient air enters the intake regulating component 3 through the rubber hose 31 for flow regulation; then it enters the intake port 411 of the primary compressor host 41 of the primary compression system 4. The primary compressor host 41 performs the first compression of the gas, discharging high-temperature and high-pressure gas;

[0076] S202: The high-temperature gas discharged from the exhaust port 412 of the first-stage compressor host 41 enters the first-stage cooling component 5 for cooling, reducing its temperature and volume, increasing the gas density, and creating conditions for the next stage of compression.

[0077] S203: The gas after primary cooling enters the secondary air inlet 611 of the two-stage compressor host 61 and is compressed a second time by the internal secondary compression rotor; the gas discharged from the secondary exhaust port 612 enters the secondary cooling assembly 7 for secondary cooling.

[0078] S204: The gas after secondary cooling enters the third-stage air inlet 613 of the two-stage compressor host 61 and is compressed for the third time by the internal three-stage compressor rotor; finally, the high-pressure gas after three-stage compression is discharged from the third-stage exhaust port 614 and then enters the three-stage exhaust assembly 8 for exhaust treatment.

[0079] S205: After noise reduction treatment by the three-stage exhaust assembly 8, the finished compressed air is discharged from the air compressor system through the outlet silencer 14 for use by end-use air equipment.

[0080] In this embodiment, the air compressor's discharge capacity can be 140m³. 3 / min to 230m 3 The system dynamically adjusts the exhaust volume within a range of / min. The electrical control system 12 performs frequency conversion control on the primary drive motor 42 and the secondary drive motor 62, and coordinates the adjustment of the butterfly valve opening of the intake adjustment component 3 to achieve wide-range and high-precision exhaust volume adjustment.

[0081] Example 5, as a further preferred embodiment of Example 1, such as Figure 7 , Figure 8As shown, the three-stage exhaust assembly 8 includes a venturi tube 81, a connecting pipe 82, an expanded perforated plate muffler 83, a transition pipe 84, a check valve 85, and an exhaust pipe 86.

[0082] The inlet end of the Venturi tube 81 is sealed to the third-stage exhaust port 614 of the two-stage compressor 61. The Venturi tube 81 has a converging section, a throat, and a diverging section. When high-pressure gas is ejected at high speed from the third-stage exhaust port 614, the converging section of the Venturi tube 81 guides the airflow to accelerate smoothly, its throat homogenizes the airflow, and the diverging section converts part of the kinetic energy of the high-speed airflow into pressure energy, reducing the exhaust velocity. This structure effectively reduces the violent shear mixing of the airflow with the surrounding still air, suppresses the generation of turbulence and vortices, and reduces aerodynamic noise at the source.

[0083] The expanded perforated plate silencer 83 is sealed to the outlet end of the venturi tube 81 via a connecting pipe 82. For example... Figure 8 As shown, the expansion-type perforated plate silencer 83 includes an expansion chamber 831 and a perforated plate 832. The expansion chamber 831 is a closed cavity whose volume is designed according to the target noise reduction frequency. It is used to receive the gas processed by the Venturi tube 81 and eliminate low-frequency noise in the airflow. The perforated plate 832 is fixedly installed on the outlet side of the expansion chamber 831, and multiple through-holes are distributed on the perforated plate 832 to eliminate high-frequency noise in the compressed gas.

[0084] In this embodiment, the expansion-type perforated plate silencer 83 adopts a unique structure of "expansion chamber first, then perforated plate," which is completely opposite to the existing "small perforated plate first, then expansion chamber" approach (such as the small perforated diffuser disclosed in patent CN119467340A). This embodiment allows the gas to first enter the expansion chamber 831 for buffering, pressure reduction, and velocity reduction before flowing through the perforated plate 832. The expansion chamber 831 buffers and pre-treats the airflow, creating a gentler acoustic environment for the subsequent perforated plate 832, preventing high-speed airflow from directly impacting the small perforated plate and causing blockage, wear, or regenerated noise. Simultaneously, the expansion chamber utilizes the Helmholtz resonance effect to preferentially eliminate low-frequency noise, while the perforated plate 832 eliminates mid-to-high-frequency noise through the small-hole injection effect. These two elements complement each other in the noise reduction spectrum, resulting in a wider noise reduction band coverage. Under the same perforation area ratio and flow rate conditions, the pressure drop loss in this embodiment is significantly lower than the scheme of "small perforated plate first, then expansion chamber," which helps reduce system energy consumption.

[0085] Furthermore, the combination of the Venturi tube 81 and the expanded perforated plate silencer 83 creates a synergistic effect of "flow stabilization-wideband noise reduction": the Venturi tube 81 guides and rectifyes the high-speed airflow, reducing airflow shear noise and lowering the outlet velocity; the expansion chamber 831 handles low-to-medium frequency noise, and the perforated plate 832 handles mid-to-high frequency noise. The combination of these three elements creates a complementary noise reduction spectrum, covering a wider frequency range and effectively addressing the noise spectrum drift caused by speed changes due to variable frequency speed control. This ensures that the air compressor maintains excellent noise reduction performance across the entire speed range.

[0086] In this embodiment, the aperture of the silencing holes on the perforated plate 832 is optimized according to the target noise reduction frequency band, preferably 2-5mm; the perforation rate is controlled between 20% and 35% to achieve the best silencing effect while ensuring flow capacity. The volume of the expansion chamber 831 is matched according to the low-frequency silencing requirements to ensure effective absorption of the main low-frequency noise components.

[0087] The gas processed by the expansion-type perforated plate silencer 83 passes sequentially through the transition pipe 84, the check valve 85, and the exhaust pipe 86, and is finally delivered to the outlet silencer 14. The check valve 85 is used to prevent external gas from flowing back to the compressor unit when the machine is stopped.

[0088] Example 6, as a further preferred embodiment of Example 1, such as Figure 10 , Figure 14 As shown, the oil cooling circulation system 10 is independent of the gas passage and is dedicated to lubricating and cooling the gearboxes of each stage of the compressor. Specifically, it includes a reservoir oil tank 101, an oil pump 102, an oil cooler 103, and several oil supply lines 104.

[0089] The oil storage tank 101 is located below the primary compression system 4 and the secondary compression system 6. The gearbox of the primary compression system 4 has an oil outlet at its bottom, which is connected to the oil inlet of the oil storage tank 101 via a return oil line. Similarly, the return oil outlet at the bottom of the gearbox of the secondary compression system 6 is also connected to another oil inlet of the oil storage tank 101 via a line. Because the oil inlet of the oil storage tank 101 is vertically lower than the gearbox outlet, the high-temperature hydraulic oil, after completing its lubrication task, can automatically flow back to the oil storage tank 101 under gravity without additional power. The oil outlet of the oil storage tank 101 is sealed to the oil inlet of the oil pump 102, and the oil outlet of the oil pump 102 is sealed to the oil inlet of the oil cooler 103. The oil outlet of the oil cooler 103 is connected to the lubrication inlet of the gearbox of the primary compression system 4 and the lubrication inlet of the gearbox of the secondary compression system 6 via an oil supply line 104.

[0090] During operation, after the oil pump 102 starts, it draws hydraulic oil from the storage tank 101 and pressurizes it to the inlet of the oil cooler 103. The oil cooler 103 adopts a plate or shell-and-tube heat exchange structure, using a cooling medium such as water or air to forcibly cool the high-temperature hydraulic oil flowing through it. The cooled hydraulic oil flows out from the outlet of the oil cooler 103 and is delivered to the gearbox lubrication inlet of the first-stage compression system 4 and the gearbox lubrication inlet of the two-stage compression system 6 through the oil supply pipeline 104. Nozzles are installed at the lubrication inlet of each gearbox, and the cooled hydraulic oil is precisely sprayed into the gearbox at a certain pressure through the nozzles to forcibly lubricate the key moving parts such as high-speed rotating gears and bearings, while removing the heat generated by friction. The hydraulic oil that has completed the lubrication and cooling functions collects back to the bottom of the gearbox of its respective compressor under the action of gravity, and then flows back to the storage tank 101, forming a closed-loop circulation circuit of "gravity return oil - pressure supply oil".

[0091] The dynamic oil cooling circulation system uses the oil storage tank 101 as a transfer hub to achieve centralized oil supply and cooling for the multi-stage compressor host, ensuring that each gearbox always receives lubricating oil with controlled temperature and stable pressure, which significantly improves the operational reliability of the system.

[0092] Example 7, as a further preferred embodiment of Example 1, such as Figure 11 As shown, the oil mist extraction assembly 11 of the compressor includes a filter box 111, a fan 112, and an air filter assembly 113. The air inlet of the filter box 111 is connected to the gearbox oil mist port of the first-stage compression system 4 and the gearbox oil mist port of the two-stage compression system 6 via an air extraction pipeline. The filter box 111 is equipped with an oil-gas separation element for preliminary separation of oil mist carried in the extracted gas. The air outlet of the filter box 111 is sealed to the air inlet of the fan 112. The air filter assembly 113 is fixedly installed at the front end of the air inlet of the fan 112 for secondary filtration of the air finally discharged into the atmosphere.

[0093] During operation, the blower 112 runs continuously, drawing oil-mist-laden gas from each gearbox through the filter box 111. As the gas is continuously drawn out, a slight negative pressure is created inside each gearbox, typically controlled between -50Pa and -200Pa. This negative pressure effectively prevents hydraulic oil from seeping into the gas compression chambers of the primary compressor 41 and the secondary compressor 61 through gaps such as shaft seals, thus avoiding contamination of the compressed air. The drawn gas undergoes preliminary separation in the filter box 111; larger oil droplets are trapped and returned to the gearbox; the gas carrying fine oil mist enters the air filter assembly 113, where it undergoes high-efficiency filtration before being discharged into the atmosphere, achieving environmentally friendly emissions. The oil mist extraction component 11 of this compressor effectively prevents hydraulic oil from entering the gas compression chamber of the compressor through gaps such as shaft seals, fundamentally ensuring the oil-free quality of the output gas.

[0094] Example 8, as a further preferred embodiment of Example 1, such as Figure 9 As shown, the water cooling system 9 includes a water pump 91, a water tank 92, a heat exchanger 93, and several cooling pipes 94. The water cooling system 9 is used to cool the single-stage drive motor 42, the double-stage drive motor 62, and the corresponding integrated frequency converter. The integrated frequency converter is used to control the operation of the single-stage drive motor 42 and the double-stage drive motor 62. It integrates a rectifier unit, an inverter unit, and a drive protection circuit, capable of converting AC power to DC power and then inverting it back to AC power with an adjustable frequency, thus achieving variable frequency speed control of the motors and providing overcurrent, overvoltage, and overheat protection functions.

[0095] This embodiment employs a parallel cooling circuit design. The inlet of water pump 91 is connected to the outlet of water tank 92, the outlet of water pump 91 is connected to the inlet of heat exchanger 93, and the outlet of heat exchanger 93 is connected back to the inlet of water tank 92, forming the main cooling fluid circulation loop. Water tank 92 is used to store and replenish coolant, and heat exchanger 93 utilizes external cooling water or air to remove heat from the coolant.

[0096] First cooling branch: The first cooling branch is led out from the outlet of the water pump 91 and connected to the cooling channel inlet of the first-stage drive motor 42 to cool the first-stage drive motor 42; after the coolant flows through the motor and the frequency converter, it flows into the inlet of the heat exchanger 93 through the return pipe (or directly returns to the water tank).

[0097] Second cooling branch: The second cooling branch is led out from the outlet of the water pump 91 and connected to the cooling channel inlet of the dual-stage drive motor 62 to cool the dual-stage drive motor 62; the coolant flows through and also flows into the heat exchanger 93.

[0098] The third cooling branch: A third cooling branch is drawn from the outlet of water pump 91 and connected to the cooling channel inlet of the integrated frequency converter to achieve precise temperature control of its power modules and heat dissipation units. After completing heat exchange, the three coolants converge into the inlet of heat exchanger 93 through independent return pipes, and then return to water tank 92 after efficient heat exchange, achieving closed-loop constant temperature operation of the entire system. The IGBT modules built into the integrated frequency converter generate significant heat during high-frequency switching; the precise temperature control ensured by the third cooling branch keeps the module junction temperature stable below 85℃, greatly reducing the risk of thermal failure and improving the reliability of continuous operation of the entire machine.

[0099] During operation, water pump 91 drives coolant into the internal cooling channels of each drive motor and frequency converter. The high-temperature coolant, after absorbing heat, enters heat exchanger 93. In heat exchanger 93, the heat of the coolant is carried away by externally circulating cooling water (or cooling air), achieving cooling. The cooled coolant returns to water tank 92, and is then repressurized and delivered to each cooling point by water pump 91, forming a dynamic cycle. This water cooling system 9 ensures that the drive motors and frequency converters operate stably within a suitable temperature range.

[0100] The parallel design of this embodiment allows the cooling of the two drive motors and their frequency converters to be independent, and the flow rate can be adjusted independently according to their respective heat loads. At the same time, they share a set of circulating power and heat dissipation units, resulting in a compact structure and high efficiency.

[0101] Example 9, as a further preferred embodiment of Example 1, such as Figure 12 , Figure 13 As shown, both the inlet muffler 13 and the outlet muffler 14 are plate-type resistive mufflers.

[0102] The imported silencer 13 is installed on the intake side of the air compressor housing 1. Its intake port is connected to the outside atmosphere, and its outlet is connected to the internal airflow channel of the air compressor housing 1, which is used to reduce intake noise. The cross-sectional area of ​​the airflow channel of the imported silencer 13 is designed according to the maximum intake flow rate of the intake air filter system 2 to ensure that no throttling effect is generated.

[0103] The outlet silencer 14 is located on the exhaust side of the air compressor housing 1. Its inlet is connected to the exhaust pipe 86 of the three-stage exhaust assembly 8, and its outlet opens to the outside atmosphere to reduce exhaust noise. The cross-sectional area of ​​the airflow channel of the outlet silencer 14 is designed based on the maximum exhaust flow rate.

[0104] The internal structures of the inlet silencer 13 and the outlet silencer 14 are identical, both employing a plate-type resistive design. Multiple sound-absorbing plates are arranged in parallel within the housings of both the inlet silencer 13 and the outlet silencer 14, forming narrow airflow channels between each plate. The sound-absorbing plates are made of the same multi-layered composite material as the sound-absorbing baffles in the labyrinthine duct 23, exhibiting excellent mid-to-high frequency sound absorption characteristics.

[0105] When airflow passes through the channels between the sound-absorbing sheets, noise energy is absorbed by the sound-absorbing material, thereby achieving a noise reduction effect. The sheet structure, while ensuring a large flow capacity, has a high noise reduction and a wide noise reduction frequency range, making it particularly suitable for the intake and exhaust noise control of the large-volume air compressor in this embodiment.

[0106] In addition, an axial flow fan (not shown in the figure) can be arranged at the outlet silencer 14. When air is driven by the axial flow fan above the outlet silencer 14, it flows in from the inlet silencer 13 and out from the outlet silencer 14, while carrying away the heat inside the casing and keeping the temperature inside the casing suitable.

[0107] Example 10, as follows Figure 2 and combined Figure 9 , Figure 10 As shown, this embodiment also provides an air compressor start-up control method, which executes pre-lubrication and pre-cooling control logic through the electrical control system 12.

[0108] During the pre-lubrication and pre-cooling stage: When the electrical control system 12 receives the air compressor start command, it does not immediately start the first-stage drive motor 42 and the second-stage drive motor 62, but instead sends a pre-start signal to the oil pump 102 of the oil cooling circulation system 10 and the water pump 91 of the water cooling system 9.

[0109] The oil pump 102 starts immediately in response to the pre-start signal, drawing hydraulic oil from the storage tank 101. After being cooled by the oil cooler 103, the oil is delivered through the oil supply line 104 to the gearboxes of the primary compression system 4 and the secondary compression system 6 to pre-lubricate the internal gears and bearings. The pre-lubrication duration is controlled by a timer in the electrical control system 12, typically set to 10-30 seconds, to ensure that the lubricating oil fully reaches the surfaces of each friction pair.

[0110] At the same time, water pump 91 starts immediately in response to the pre-start signal, driving the coolant to circulate in the main circuit and parallel branches of the water cooling system 9. The coolant flows through the cooling channels of the primary drive motor 42, the secondary drive motor 62, and the corresponding integrated frequency converter, pre-cooling the motor stator, rotor, and power module, and removing the heat accumulated during shutdown.

[0111] During the main unit startup phase: After the oil pump 102 and water pump 91 have run for a preset time (e.g., 20 seconds) or the oil pressure and water pressure have reached a preset threshold, the electrical control system 12 determines that pre-lubrication and pre-cooling have been completed. At this time, the electrical control system 12 sends a main unit startup signal to the primary drive motor 42 and the secondary drive motor 62, and the air compressor begins its normal compression cycle.

[0112] The aforementioned pre-lubrication and pre-cooling control logic effectively prevents the main unit from starting directly in a cold state or without lubrication, significantly reducing starting wear and extending the life of the main unit. It is especially suitable for three-stage compressor units with large air volume and high load.

[0113] Furthermore, this embodiment also provides a venting and dust prevention function in the unloaded state. When the air compressor is in the unloaded (no-load) operation state, excess compressed gas will be generated at the third-stage exhaust end. In this embodiment, the electrical control system 12 controls the relevant valves to guide this excess gas back to the air filter housing 22 of the intake air filter system 2 through a dedicated venting pipeline, and simultaneously connects to the venting valve of the intake regulating component 3. This not only guides the excess gas back to the air filter housing, but also utilizes the volume of the air filter housing and the damping effect of the labyrinth-type air duct 23 to allow the pressure in the pipeline to be released quickly and safely during unloading, avoiding the impact noise caused by sudden pressure changes; at the same time, the returned gas creates a slight positive pressure inside the air filter housing 22. This positive pressure state can effectively prevent dust and impurities from the external environment from entering through the gaps or door seals of the air filter housing, ensuring the cleanliness of the intake air filter system and extending the service life of the air filter element 21.

[0114] This invention successfully achieves 140m³ compression through the rational matching and integration design of a three-stage compression system. 3 / min to 230m 3 The air compressor boasts a wide-range discharge capacity adjustment capability of [value missing] / min. The coordinated operation of the primary compression system 4 and the secondary compression system 6, combined with variable frequency speed control technology and precise control of the intake regulating component 3, enables the air compressor to dynamically adjust the discharge capacity according to the actual air load, avoiding energy waste. This wide-range adjustment capability allows the air compressor of this invention to meet the peak demands of large-scale air consumption scenarios while achieving energy-saving operation during low-load periods.

[0115] Furthermore, this invention optimizes the layout of the functional modules within the chassis. The primary cooling component 5 is placed below the dual-stage drive motor 62, the secondary cooling component 7 is placed below the dual-stage compressor host 61, and the water cooling system 9 and oil cooling circulation system 10 are stacked on top of the primary cooling component 5, forming a highly integrated three-dimensional layout structure. This significantly shortens the connecting pipes between components, reducing airflow resistance and pressure loss, while also lowering the risk of pipe leakage. It also fully utilizes the unused space below the motor and host, making the overall structure more compact and facilitating transportation and installation. Simultaneously, it provides easily accessible operating space for components requiring regular maintenance, such as coolers, filters, and oil pumps, making daily maintenance and troubleshooting more convenient and effectively reducing the total life-cycle cost of the equipment.

[0116] This invention constructs a comprehensive, multi-stage noise reduction system from the intake to the exhaust end, significantly improving the noise control level of large-volume oil-free screw air compressors and solving the technical problem of existing technologies being unable to cope with broadband noise and noise fluctuations under variable frequency conditions. At the intake end, a labyrinthine air duct 23 is installed inside the intake air filter system 2, forming a tortuous labyrinthine path within the airflow channel through multiple staggered multi-layer composite material sound-absorbing baffles. This allows for multiple reflections and effective absorption of high-frequency noise propagating from the compressor to the intake port without increasing intake resistance, significantly reducing the noise radiated from the intake port. At the exhaust end, the three-stage exhaust assembly 8 adopts a combined structure of a venturi tube 81 and an expanding perforated plate silencer 83. The venturi tube 81 guides and rectifyes the high-speed airflow ejected from the three-stage exhaust port 614, reducing turbulent noise generated by airflow shearing. Simultaneously, the expanding section converts kinetic energy into pressure energy, reducing the outlet velocity and reducing aerodynamic noise at its source. The expansion-type perforated plate silencer 83 employs a unique structure consisting of an expansion chamber 831 followed by a perforated plate 832. The expansion chamber 831 buffers, reduces pressure and speed of the airflow, and utilizes the Helmholtz resonance effect to eliminate low-frequency noise. The perforated plate 832 eliminates mid-to-high-frequency noise through the small-hole injection effect. The combination of these two components forms a complete noise reduction chain, enabling the noise reduction spectrum to cover a wider frequency range. This effectively addresses the noise spectrum drift caused by speed changes due to variable frequency speed control, ensuring the air compressor maintains excellent noise reduction performance across the entire speed range. Furthermore, by incorporating a plate-type resistive inlet silencer 13 and an outlet silencer 14, whose airflow channel cross-sectional area is matched to high-flow conditions, the silencer effectively absorbs mid-to-high-frequency noise in the airflow while avoiding additional pressure loss.

[0117] This invention designs a dynamic oil cooling circulation system 10 with a storage oil tank 101 as its core, providing a stable and reliable lubrication and cooling solution for the gearboxes of multi-stage compression main units. Through a closed-loop circulation circuit of "gravity return oil - pressure supply oil," firstly, the storage oil tank 101 is located below each gearbox, allowing high-temperature hydraulic oil to automatically return by gravity without additional power, thus saving energy and ensuring reliability. The return oil from the gearboxes of the first-stage compression system 4 and the second-stage compression system 6 is collected in the lower-positioned storage oil tank 101, then pumped by the oil pump 102 and sent to the oil cooler 103 for forced cooling, ensuring that the temperature of the lubricating oil entering the gearbox remains within a suitable range, guaranteeing lubrication effectiveness. Finally, the temperature-controlled hydraulic oil is precisely sprayed onto the key moving parts of each gearbox. The storage oil tank 101 simultaneously serves as an oil storage and buffer, preventing cavitation caused by the oil pump 102 directly drawing in high-temperature return oil, thus improving the operational stability of the oil circuit system. Furthermore, the gearboxes of each compressor share the same set of oil pump 102 and oil cooler 103, which simplifies the oil circuit structure and reduces system complexity; and the circulation loop design allows hydraulic oil to be reused, reducing oil costs.

[0118] The butterfly valve 32 maintains a slightly open position at a preset angle when the compressor is stopped or in standby mode. This allows the compressor to quickly establish initial internal pressure during startup, providing the actuator with the power to open and ensuring a smooth start-up. It also avoids airflow impact caused by sudden valve opening. The compressor's oil mist extraction assembly 11 continuously extracts oil-mist gas from each gearbox, maintaining a slight negative pressure inside the gearbox. This effectively prevents hydraulic oil from entering the compression chamber through gaps such as shaft seals, fundamentally ensuring the oil-free quality of the output gas.

[0119] Through the intelligent control logic built into the electrical control system 12, the oil pump 102 and water pump 91 are prioritized for startup before the air compressor main unit starts, pre-lubricating the gearboxes of each stage of the compressor main unit and pre-cooling the drive motor and integrated frequency converter power supply. This control logic ensures that a stable lubricating oil film has been established on the key friction pairs of the compressor main unit at the moment of startup, avoiding abnormal wear caused by dry friction; at the same time, the motor and integrated frequency converter power supply are at a suitable initial temperature before starting work, avoiding thermal stress shock caused by cold start. This pre-start strategy significantly reduces the startup failure rate of the equipment and effectively extends the service life of the entire machine.

[0120] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oil-free screw air compressor, characterized in that: The system includes a chassis (1), on which an air intake filter system (2) is fixedly installed. Inside the chassis (1), an air intake regulating component (3), a primary compression system (4), a primary cooling component (5), a dual compression system (6), a secondary cooling component (7), a tertiary exhaust component (8), a water cooling system (9), and an oil cooling circulation system (10) are fixedly installed. The air intake regulating component (3) is connected to the air intake filter system (2) through a pipeline. The air intake port of the primary compression system (4) is connected to the air outlet of the air intake regulating component (3), and the air intake port of the primary cooling component (5) is connected to the exhaust port of the primary compression system (4). The two-stage compression system (6) includes a two-stage compressor host (61) and a two-stage drive motor (62) that drives the two-stage compressor host (61); the two-stage compressor host (61) has a second-stage air inlet (611), a third-stage air inlet (613) and a third-stage exhaust port (614), and the second-stage air inlet (611) is connected to the exhaust port of the first-stage cooling assembly (5); The air inlet of the secondary cooling component (7) is connected to the secondary exhaust port of the dual-stage compressor (61), and the exhaust port of the secondary cooling component (7) is connected to the tertiary air inlet (613) of the dual-stage compressor (61); the air inlet of the tertiary exhaust component (8) is connected to the tertiary exhaust port (614) of the dual-stage compressor (61), and the exhaust port of the tertiary exhaust component (8) is used to output clean high-pressure gas after three-stage compression and precision cooling to the outside. The water cooling system (9) is used to cool the drive motors of the primary compression system (4) and the secondary compression system (6); the oil cooling circulation system (10) is used to continuously provide cooling lubricating oil for the primary compression system (4) and the secondary compression system (6).

2. The oil-free screw air compressor according to claim 1, characterized in that: The primary cooling assembly (5) is located below the dual-stage drive motor (62); the secondary cooling assembly (7) is located below the dual-stage compressor host (61); the water cooling system (9) and the oil cooling circulation system (10) are both located above the primary cooling assembly (5).

3. The oil-free screw air compressor according to claim 1, characterized in that: The air intake air filter system (2) includes an air filter housing (22) and a labyrinth-type air duct (23) disposed inside it. The air outlet of the air filter housing (22) is connected to the air intake regulating component (3) through a rubber hose (31). An air filter (21) is disposed inside the air filter housing (22). The labyrinth-type air duct (23) is located on the airflow channel between the air filter (21) and the air outlet of the air filter housing (22). The labyrinth-type air duct (23) is composed of multiple staggered sound-absorbing baffles, forming a tortuous labyrinth-shaped airflow path in the airflow channel. The sound-absorbing baffle is a sound-absorbing structure made of multi-layer composite material, used to reflect and absorb high-frequency noise that is transmitted in reverse from the primary compression system (4) and the secondary compression system (6) to the intake air filter system (2) multiple times.

4. The oil-free screw air compressor according to claim 1, characterized in that: The three-stage exhaust assembly (8) includes a venturi tube (81) and an expanded perforated plate muffler (83); the intake end of the venturi tube (81) is sealed to the three-stage exhaust port (614), and the exhaust side of the venturi tube (81) is connected to the expanded perforated plate muffler (83). The expansion-type perforated plate silencer (83) includes an expansion chamber (831) and a perforated plate (832). The expansion chamber (831) is a closed cavity used to receive gas after it has been processed by the venturi tube (81) and to eliminate low-frequency noise in the airflow. The perforated plate (832) is fixedly installed on the outlet side of the expansion chamber (831). The perforated plate (832) has multiple through-holes for eliminating high-frequency noise in the compressed gas.

5. An oil-free screw air compressor according to claim 1, characterized in that: The oil cooling circulation system (10) includes a storage oil tank (101) and an oil pump (102). The oil inlet of the storage oil tank (101) is connected to the gearbox oil outlet of the first-stage compression system (4) and the gearbox oil outlet of the second-stage compression system (6), respectively. The oil outlet of the storage oil tank (101) is connected to the oil inlet of the oil pump (102), and the oil outlet of the oil pump (102) is sealed to the oil inlet of the oil cooler (103). The oil outlet of the oil cooler (103) is connected to the gearbox lubrication inlet of the first-stage compression system (4) and the gearbox lubricating oil inlet of the second-stage compression system (6) through an oil supply pipeline (104), respectively. The oil inlet of the storage tank (101) is positioned vertically lower than the gearbox outlet of the primary compression system (4) and the gearbox outlet of the secondary compression system (6), so that the high-temperature hydraulic oil flows into the storage tank (101) by gravity.

6. The oil-free screw air compressor according to claim 1, characterized in that: It also includes a compressor main unit oil mist extraction assembly (11) installed inside the air compressor housing (1). The compressor main unit oil mist extraction assembly (11) includes a filter box (111) and a fan (112). The air inlet of the filter box (111) is connected to the gearbox oil mist port of the first-stage compression system (4) and the gearbox oil mist port of the two-stage compression system (6) through pipelines respectively. The air outlet of the filter box (111) is sealed to the air inlet of the fan (112). An air filter assembly (113) is fixedly installed at the front end of the air inlet of the fan (112). The fan (112) is used to extract oil mist-containing gas from the gearboxes of the first-stage compression system (4) and the two-stage compression system (6) through the filter box (111) to create a negative pressure state inside each gearbox.

7. An oil-free screw air compressor according to claim 1, characterized in that: It also includes an inlet silencer (13) and an outlet silencer (14). The inlet silencer (13) is located on the air intake side of the air compressor housing (1) and is connected to the internal airflow channel of the air compressor housing (1). The outlet silencer (14) is located on the exhaust side of the air compressor housing (1). Both the inlet muffler (13) and the outlet muffler (14) are plate-type resistive mufflers; the cross-sectional area of ​​the airflow channel of the inlet muffler (13) is matched with the airflow of the air intake air filter system (2), and the cross-sectional area of ​​the airflow channel of the outlet muffler (14) is matched with the exhaust flow of the three-stage exhaust assembly (8).

8. An oil-free screw air compressor according to claim 1, characterized in that: The water cooling system (9) includes a water pump (91), a water tank (92), a heat exchanger (93), a first cooling branch, a second cooling branch, and a third cooling branch; the inlet of the water pump (91) is connected to the outlet of the water tank (92), the inlet of the heat exchanger (93) is connected to the outlet of the water pump (91), and the outlet of the heat exchanger (93) is connected to the water tank (92), forming a main loop for cooling liquid circulation; the first cooling branch is connected between the outlet of the water pump (91) and the cooling channel of the first-stage drive motor (42) of the first-stage compression system (4), and is used to cool the first-stage drive motor (42); the second cooling branch is connected between the outlet of the water pump (91) and the cooling channel of the second-stage drive motor (62) of the second-stage compression system (6), and is used to cool the second-stage drive motor (62); The third cooling branch is connected between the outlet of the water pump (91) and the cooling channel of the integrated frequency converter, and is used to cool the integrated frequency converter. The integrated frequency converter is used to provide adjustable frequency drive signals for the single-stage drive motor (42) and the double-stage drive motor (62).

9. An oil-free screw air compressor according to claim 5 or 8, characterized in that: It also includes an electrical control system (12), which is installed inside the chassis (1) and is configured to execute pre-lubrication and pre-cooling control logic, specifically including: In response to the air compressor start command, the electrical control system (12) first sends a pre-start signal to the oil pump (102) of the oil cooling circulation system (10) and the water pump (91) of the water cooling system (9) before sending the main unit start signal to the primary compression system (4) and the secondary compression system (6); In response to the pre-start signal, the oil pump (102) draws hydraulic oil from the storage tank (101), cools it through the oil cooler (103), and then delivers it to the gearbox of the primary compression system (4) and the secondary compression system (6) to pre-lubricate the gears and bearings. The water pump (91) responds to the pre-start signal and drives the coolant to circulate in the water cooling system (9) to pre-cool the drive motor (42) of the first-stage compression system (4), the drive motor (62) of the second-stage compression system (6) and the integrated frequency converter power supply. After the oil pump (102) and the water pump (91) have reached a preset time threshold or a preset pressure threshold, the electrical control system (12) sends a host start signal to the primary compression system (4) and the secondary compression system (6).

10. An oil-free screw air compressor according to claim 1, characterized in that: The intake regulating component (3) includes a butterfly valve (32), the valve plate of which is configured to maintain a slightly open state at a preset angle when the air compressor is in a stopped or standby state.

Images