Oxygen generator with mute structure

Abstract

The application discloses an oxygen generator with a mute structure and belongs to the technical field of gas separation equipment, comprising: a shell assembly, an internal main frame, a power-gas path core module, a multi-point elastic suspension system, a multi-stage composite exhaust silencing assembly and a control unit. The power-gas path core module is suspended in the internal main frame through the multi-point elastic suspension system, effectively isolating vibration; the exhaust silencing assembly suppresses gas discharge noise; the shell adopts a constraint damping laminated board and covers sound-absorbing cotton to block sound absorption; internal connections are all flexible; and the control unit adopts a valve slow opening and slow closing strategy. The application has the beneficial effects that: by adopting the above technical scheme, the application can greatly reduce the overall operation noise of the equipment, improve user comfort, and realize the balance between oxygen production performance and mute effect.

Description

Technical Field

[0001] This invention relates to the field of gas separation equipment technology, and in particular to an oxygen generator with a silent structure. Background Technology

[0002] Oxygen concentrators, as key devices capable of separating and enriching oxygen from ambient air, play a vital role in modern healthcare, home oxygen therapy, and specific industrial production fields. Especially in medical and personal health applications, with the increasing trend of population aging and people's rising demands for quality of life, the market demand and technological attention for home or medical oxygen concentrators that can provide continuous, stable, and high-concentration oxygen are both growing. Currently, among mainstream technologies, oxygen concentrators based on the pressure swing adsorption (PSA) principle dominate due to their advantages such as rapid start-up, high oxygen concentration, relatively compact structure, and low operating costs. Specifically, the core of PSA oxygen generation technology lies in utilizing the difference in adsorption capacity of molecular sieves for nitrogen and oxygen in the air under different pressures to achieve gas separation. Its workflow typically begins with a core power unit—a compressor—which draws in and pressurizes ambient air. Subsequently, the high-pressure air is introduced into an adsorption tower filled with special molecular sieves. Under this high-pressure environment, the molecular sieve preferentially and selectively adsorbs a large amount of nitrogen molecules, while adsorbing a relatively small amount of oxygen molecules. This allows the unadsorbed gas, with a significantly increased oxygen concentration, to pass through the adsorption tower and be collected. To achieve continuous oxygen production, the system typically uses two or more adsorption towers that operate alternately. While one adsorption tower is performing high-pressure adsorption for oxygen production, another adsorption tower enters a low-pressure desorption state. By reducing its internal pressure, the previously adsorbed nitrogen is released and vented, thus regenerating the molecular sieve and preparing it for the next adsorption cycle. It is this ingenious design, which drives the adsorption and desorption processes through periodic pressure "variations," that enables PSA oxygen generators to efficiently and economically meet a wide range of oxygen needs, from clinical treatment to home healthcare, effectively solving the problems of traditional cryogenic air separation equipment being bulky, energy-intensive, and unable to be miniaturized.

[0003] However, as the application scenarios of oxygen concentrators continue to deepen, especially their increasing popularity in places with extremely high requirements for quiet environments, such as home bedrooms and nursing homes, some inherent characteristics of the above-mentioned technical solutions at the principle level have gradually revealed profound limitations in addressing the new challenge of "quiet operation." At its root, there is an inherent and irreconcilable technical contradiction between the efficient operation of PSA oxygen concentrators and the generation of noise. This contradiction mainly stems from two aspects: First, the mechanical structural noise generated by the compressor, which is the "heart" of the system. To ensure that the molecular sieve can fully adsorb nitrogen under high pressure, thereby guaranteeing that the oxygen production concentration and flow rate meet the standards, the PSA system must be equipped with a powerful compressor. Such compressors, especially the piston or diaphragm compressors commonly used for oil-free cleanliness requirements, inevitably generate strong vibrations and low-to-mid-frequency structural noise due to the impact and friction of their internal mechanical parts and the pressure pulsations caused by the rapid compression of gas during high-speed reciprocating motion. This vibration and noise radiate outward through the rigid structure of the machine, forming a continuous humming sound. Secondly, there is the gas dynamic noise inherent in the pressure swing adsorption (PSA) process itself. During the desorption phase, when the adsorption tower pressure changes rapidly, a large amount of compressed nitrogen waste gas needs to be released instantaneously into the atmosphere through the exhaust valve. This process generates significant high-frequency airflow noise, i.e., a sharp "hissing" sound. To improve oxygen production efficiency, this pressure swing cycle is usually performed at a high frequency, leading to frequent exhaust noise. Therefore, the final operating noise of an oxygen concentrator is actually a complex mixture of compressor mechanical noise and periodic gas exhaust noise. Furthermore, conventional technical approaches to improving oxygen production performance (such as increasing oxygen production or concentration) often involve increasing compressor power or operating pressure, but this inevitably leads to a simultaneous deterioration of both mechanical and gas dynamic noise. This trade-off between performance and quietness constitutes a bottleneck that is difficult to overcome within the current technological framework. For users who need to use oxygen concentrators for extended periods, especially at night, this composite noise is not just a simple auditory disturbance but can also seriously affect their sleep quality and physical and mental health, thus contradicting the original intention of oxygen therapy.

[0004] Therefore, how to systematically suppress and isolate the combined noise from the compressor and gas circulation system through innovative structural design without significantly sacrificing the core performance indicators of oxygen production efficiency, concentration, and equipment stability, in order to effectively resolve the inherent contradiction between oxygen production performance and quiet comfort, has become a key challenge and an urgent technical problem for those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the combined noise problem caused by compressor mechanical vibration and periodic gas emission during the operation of some existing pressure swing adsorption oxygen generators. In this way, without significantly affecting oxygen production efficiency and concentration, the overall operating noise of the equipment is greatly reduced, the user's comfort is improved, and the inherent technical contradiction between oxygen production performance and quiet operation is resolved, thus providing an oxygen generator with a quiet structure.

[0006] The objective of this invention is achieved through the following technical solution: an oxygen concentrator with a silent structure, comprising an outer shell assembly and an internal main frame disposed inside the outer shell assembly;

[0007] The power-air circuit core module integrates an oil-free reciprocating compressor for generating compressed air, a molecular sieve adsorption tower for realizing pressure swing adsorption cycle, and a solenoid valve group for controlling the on / off of the air circuit.

[0008] The multi-point elastic suspension system suspends the power-air circuit core module above the internal main frame, thereby achieving vibration isolation between the power-air circuit core module and the internal main frame.

[0009] The multi-stage composite exhaust muffler assembly has its inlet end connected to the exhaust pipe of the solenoid valve group in the power-air circuit core module, which is used to muffle the exhaust gas generated by the pressure swing adsorption cycle.

[0010] The control unit, electrically connected to the power-air circuit core module and the multi-stage composite exhaust muffler assembly, is used to coordinate and control the overall operation of the oxygen generator.

[0011] A further technical solution involves an integrated power-gas circuit core module, which serves as the primary unit generating vibration and noise. This module integrates the core components required for the oxygen production process. It also includes a core module base plate, an oil-free reciprocating compressor, a molecular sieve adsorption tower, a solenoid valve assembly, a cooling fan for compressor heat dissipation, and a pressure equalization tank for balancing gas pressure. All components are uniformly mounted and fixed on this base plate. The oil-filled reciprocating compressor's inlet is connected to an intake filter. The core module base plate is made of cast aluminum alloy through integral die-casting, and its bottom surface features multiple reinforcing ribs arranged in a grid pattern. This core module base plate, made of A356.0 cast aluminum alloy through integral die-casting, ensures sufficient structural strength and excellent heat dissipation performance.

[0012] A further technical solution is that the multi-point elastic suspension system is a four-point elastic suspension system, with a suspension pivot point set at each of the four corners of the power-air circuit core module; each suspension pivot point is composed of a high-damping composite elastomer, the upper end of which is fixed to the power-air circuit core module by upper connecting bolts, and the lower end of which is fixed to the internal main frame by lower connecting bolts; the high-damping composite elastomer has a cylindrical structure, which is composed of a silicone rubber matrix and a helical steel spring embedded in the center of the silicone rubber matrix.

[0013] The internal main frame is the load-bearing structure of the entire oxygen concentrator. It is composed of multiple extruded aluminum alloy profiles connected by high-strength bolts, forming a stable open frame structure. This internal main frame is independent of the outer shell assembly. Its main function is to serve as the suspension base for the core power-air circuit module, and it also supports the installation of the multi-stage composite exhaust muffler assembly and control unit. This design, which separates the load-bearing structure from the enclosed outer shell, prevents vibration energy from being directly transmitted to the outer shell, which serves as the final acoustic radiation surface.

[0014] The power-airflow core module is not directly and rigidly connected to the internal main frame or outer shell of the oxygen concentrator. Instead, it is completely decoupled from the internal main frame through a multi-point elastic suspension system. Specifically, this multi-point elastic suspension system is a four-point system, with a suspension fulcrum at each of the four corners of the core module base plate. Each suspension fulcrum consists of a high-damping composite elastomer, an upper connecting bolt, and a lower connecting bolt. The high-damping composite elastomer has a cylindrical structure, composed of a silicone rubber matrix with a Shore A hardness of 45 and an embedded helical steel spring. This structure provides both elastic support and efficient vibration energy absorption. The upper connecting bolt passes through a pre-drilled hole in the core module base plate and is threaded onto the upper end face of the high-damping composite elastomer. The lower connecting bolt then fixes the lower end face of the high-damping composite elastomer to the corresponding load-bearing point on the internal main frame. With this suspension design, most of the low- and medium-frequency mechanical vibration energy generated by the compressor is absorbed and dissipated by four high-damping composite elastomers before it is transmitted to the internal main frame, thus fundamentally cutting off the main propagation path of structural vibration noise radiating to the outside of the machine.

[0015] A further technical solution is that the outer shell assembly is composed of multiple panels spliced ​​together, and each panel adopts a constrained damping laminate structure. The constrained damping laminate structure includes, from the outside to the inside: a layer of cold-rolled steel plate as the outer panel, a layer of acrylic viscoelastic polymer as the damping core layer, and a layer of aluminum alloy plate as the inner panel. The outer panel, the damping core layer and the inner panel are tightly bonded together by a hot-pressing composite process.

[0016] The housing assembly features specialized acoustic optimization in both materials and structure to block and absorb residual airborne and structural noise leaking from the interior. The housing assembly is composed of multiple panels, each employing a constrained damping laminate structure. Specifically, this laminate structure, from the outside in, comprises: a 1.2 mm thick SPCC cold-rolled steel sheet as the outer panel, providing structural strength and surface texture; a 1 mm thick acrylic viscoelastic polymer as the damping core layer, which exhibits extremely high internal friction, effectively converting the bending vibration energy of the sheet into heat energy; and a 1.0 mm thick aluminum alloy sheet as the inner panel. These three layers are tightly bonded together using a hot-pressing composite process. When sound waves excite vibration in the outer panel, the shear deformation of the inner and outer metal plates forces the intermediate viscoelastic damping layer to undergo shear deformation, thereby efficiently dissipating vibration energy and significantly improving the housing's sound insulation and anti-resonance capabilities.

[0017] A further technical solution is that a layer of high-density polyurethane sound-absorbing cotton is covered on the inner panel of all panels of the outer casing assembly facing the inside of the oxygen concentrator; and the side of the high-density polyurethane sound-absorbing cotton facing the inside of the oxygen concentrator is processed into a wave-shaped surface structure with a preset depth and spacing.

[0018] The side of the high-density polyurethane sound-absorbing cotton facing the interior of the machine is processed into a wave-shaped (egg-box-shaped) surface with specific depth and spacing. This irregular surface morphology greatly increases the contact area between the sound-absorbing material and the air, and has an excellent absorption effect on airborne sound in the mid-to-high frequency range. It can effectively absorb the residual noise radiated from the surface of the power-air circuit core module and the residual noise leaked from the exhaust muffler assembly, further reducing the sound energy density of the internal cavity of the machine and preventing sound waves from reverberating in the cavity.

[0019] A further technical solution is that the interior of the multi-stage composite exhaust muffler assembly is divided into three functional chambers along the gas flow direction. The three functional chambers include: a first expansion chamber that is directly connected to the exhaust pipe of the solenoid valve assembly; a multi-channel dissipation section that is connected to the outlet of the first expansion chamber; and a second expansion chamber that is connected to the outlet of the multi-channel dissipation section and has a final exhaust port.

[0020] A further technical solution is to install a Helmholtz resonator on the side wall of the first expansion cavity. The Helmholtz resonator consists of a neck tube with a preset inner diameter and length and a closed cavity with a preset volume. Its resonant frequency is designed to match the dominant low-frequency component in the pulse noise generated when the solenoid valve assembly exhausts.

[0021] A porous metal tube with a preset porosity is installed in the center of the porous channel dissipation section, and basalt fiber sound-absorbing material is filled between the porous metal tube and the outer shell of the sound-absorbing assembly.

[0022] The second expansion chamber is equipped with multiple flow guide baffles installed at a 45-degree angle. The flow guide baffles force the airflow to form a tortuous "S"-shaped flow path within the second expansion chamber.

[0023] To address the severe aerodynamic noise generated by exhaust gas emissions in pressure swing adsorption (PSA) cycles, this invention designs a multi-stage composite exhaust muffler assembly. This assembly is not a simple resistive muffler, but a composite structure integrating multiple silencing principles such as expansion, resonance, porous dissipation, and tortuous channels. It is cylindrical in shape, with the outer shell injection-molded from high-strength polypropylene (PP). Internally, along the gas flow direction, it is sequentially divided into a first expansion chamber, a porous dissipation section, and a second expansion chamber.

[0024] Specifically, the first expansion chamber is directly connected to the exhaust manifold of the solenoid valve assembly of the power-air circuit core module. When high-pressure nitrogen exhaust gas is discharged instantaneously, it first enters this chamber. Due to the sudden increase in cross-sectional area, the airflow velocity drops sharply, and the pressure pulsation intensity is initially weakened, achieving the first stage of expansion silencing. In particular, a Helmholtz resonator structure is installed on the side wall of this chamber. This resonator consists of a neck tube with an inner diameter of 10 mm and a length of 30 mm and a closed cavity with a volume of 250 cubic centimeters. The resonant frequency of this resonator is precisely designed to match the dominant low-frequency noise component in the exhaust pulse, maximizing the absorption and conversion of sound energy at this specific frequency through the principle of acoustic resonance.

[0025] After passing through the first expansion chamber, the gas enters the porous dissipation section. A porous metal tube is located at the center of this section, and basalt fiber sound-absorbing material is filled between the porous tube and the outer shell of the sound-absorbing assembly. When airflow containing mid-to-high frequency noise components passes through this section, sound waves penetrate through the small holes into the interior of the basalt fiber material. Within the complex pores formed by countless tiny fibers, due to the viscosity of the air and friction with the fibers, a large amount of sound energy is converted into heat energy and dissipated.

[0026] Finally, the gas enters the second expansion chamber. This chamber contains multiple baffles installed at a 45-degree angle, forcing the airflow into a tortuous "S"-shaped flow path. This design achieves secondary expansion noise reduction by further expanding the flow cross-section. Furthermore, the tortuous path increases the number of sound wave reflections; each reflection results in energy loss, effectively suppressing external noise from flowing back into the engine along the exhaust pipe. After this three-stage composite treatment, the exhaust noise sound pressure level is reduced to an extremely low level, and is finally gently released into the environment through the exhaust port at the end of the muffler assembly.

[0027] To ensure the integrity of the vibration isolation system, this invention employs flexible design for all connections between the power-air circuit core module and other parts of the machine body. The air passage connecting the oxygen production outlet of the power-air circuit core module to the user oxygen intake interface on the outer casing assembly, and the air passage connecting the exhaust manifold of the solenoid valve group to the inlet of the multi-stage composite exhaust silencer assembly, all utilize corrugated flexible hoses. These hoses have extremely low bending stiffness, effectively absorbing and isolating relative displacement and vibration between the two interfaces, preventing vibration transmission through the pipelines. For electrical connections, the wiring harnesses leading from the control unit mounted on the internal main frame to the compressor motor, cooling fan, and solenoid valve group on the power-air circuit core module are all designed with a slack margin of at least 50 mm, naturally forming a U-shaped arc to avoid creating a "sound bridge" for vibration transmission due to wiring harness tension.

[0028] A further technical solution involves configuring the control unit to employ a slow-opening, slow-closing valve drive strategy to control the opening and closing of the solenoid valves in the solenoid valve assembly. The core of this control unit is a 32-bit ARM Cortex-M4 microprocessor with a main frequency of no less than 120 MHz. To address the issue of sudden pressure changes in the gas path caused by rapid opening and closing of the solenoid valve, resulting in impact noise, the control unit employs a slow-opening, slow-closing valve drive strategy. Specifically, instead of outputting a simple step-switching switch signal to the solenoid valve drive circuit, the control unit outputs a pulse width modulation (PWM) signal. The duty cycle of the PWM signal gradually changes according to a preset S-shaped acceleration / deceleration curve during the initial stage of valve opening and the final stage of valve closing, making the valve core displacement process smoother and thus mitigating the on / off process of the gas path. This smooth transition time between opening and closing is set to 100 milliseconds. This control method, from the perspective of the sound source generation mechanism, reduces the intensity of gas dynamic noise, complementing the physical noise reduction structure at the back end.

[0029] This invention offers the following advantages: By constructing a floating internal structure with multi-point elastic suspension centered on a "power-airflow core module," the invention fundamentally isolates the primary solid vibration source. Simultaneously, a multi-stage composite exhaust noise reduction assembly is designed to efficiently suppress high-intensity gas emission noise. Furthermore, it is supplemented by an acoustically optimized shell composed of a constraint-damping laminate structure and high-density sound-absorbing cotton, along with comprehensive flexible connections and advanced valve control algorithms. These technologies are organically combined into a complete, multi-layered, systematic noise reduction solution, enabling the oxygen concentrator to maintain high-performance output while fundamentally controlling its overall operating noise. This solves the existing technological dilemma of the trade-off between performance and quiet operation, significantly enhancing the equipment's application value and user experience. Attached Figure Description

[0030] Figure 1This is a side view sectional diagram of the structure of the present invention;

[0031] Figure 2 This is a front view of the cross-sectional structure of the present invention;

[0032] Figure 3 This is a cross-sectional schematic diagram of the multi-stage composite exhaust muffler assembly of the present invention;

[0033] Figure 4 This is a schematic diagram of the composite structure of the outer shell assembly of the present invention;

[0034] In the diagram, 1. Outer shell assembly; 2. Internal main frame; 3. Power-air circuit core module; 4. Multi-point elastic suspension system; 5. Multi-stage composite exhaust muffler assembly; 6. Control unit; 10. Outer panel; 11. Damping core layer; 12. Inner panel; 13. High-density polyurethane sound-absorbing cotton; 20. Core module substrate; 21. Oil-free piston compressor; 22. Molecular sieve adsorption tower; 23. Solenoid valve assembly; 24. Pressure equalization tank; 25. Cooling fan; 30. High-damping composite elastomer; 31. Upper connecting bolt; 32. Lower connecting bolt; 40. First expansion chamber; 41. Helmholtz resonator; 42. Porous channel dissipation section; 43. Porous metal tube; 44. Basalt fiber sound-absorbing material; 45. Second expansion chamber; 46. Flow guide baffle; 50. Corrugated hose. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0039] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0040] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Example 1: The core of this invention lies in constructing a multi-layered, comprehensive noise and vibration control system. This system works synergistically from three dimensions: isolation of vibration sources, blocking of noise propagation paths, and absorption of noise itself. The entire machine mainly consists of an outer shell assembly 1, an internal main frame 2 located inside the outer shell assembly 1, a power-air circuit core module 3 suspended on the internal main frame 2 via an innovative multi-point elastic suspension system 4, a multi-stage composite exhaust muffler assembly 5 connected to the exhaust pipe of the power-air circuit core module 3, and a control unit 6 for coordinating and controlling the operation of the entire machine.

[0042] Among them, the power-air circuit core module 3 is the main source of mechanical vibration and aerodynamic noise during the operation of the oxygen generator. This invention does not adopt the traditional design approach of dispersing noise sources or rigidly mounting them directly to the casing. Instead, it innovatively integrates all major noise-generating components into a single unit, which is completely vibration-decoupled from the machine's main load-bearing structure, i.e., the internal main frame 2, in a "floating" manner through a multi-point elastic suspension system 4. This internal main frame 2 itself maintains structural independence from the outer shell assembly 1, which serves as the final acoustic radiation surface. Simultaneously, to address the unavoidable periodic high-pressure exhaust noise in the pressure swing adsorption cycle, this invention designs a highly efficient multi-stage composite exhaust silencing assembly 5. Finally, by employing a specially acoustically designed outer shell assembly 1 and flexibly treating all connections that could potentially form "sound bridges," a final acoustic defense line is constructed. The following will provide a detailed engineering explanation of the design details, material selection, process parameters, and collaborative working mechanisms of each component.

[0043] In one specific embodiment, the power-airflow core module 3 is the starting point and core of the silent design of this invention. For example... Figure 2 As shown, this module integrates key dynamic components and gas path elements in the oxygen production process onto a high-rigidity core module substrate 20. Specifically, the module includes a 250-watt oil-free reciprocating compressor 21 with a dual-cylinder opposed structure for self-balancing. The air inlet of the oil-free reciprocating compressor 21 is connected to an intake filter with both primary and high-efficiency filtration functions via a standard pipeline. To ensure the long-term stable operation of the oil-free reciprocating compressor 21, a cooling fan 25 is installed near its cylinder heat sink, which can provide a forced convection airflow of 60 cubic feet per minute (CFM) at a rated voltage of 12 volts. In terms of the gas path, the module integrates two molecular sieve adsorption towers 22 for achieving pressure swing adsorption (PSA) cycles, each filled with 1.2 kg of lithium-based molecular sieves with a particle size ranging from 0.4 to 0.8 mm. In addition, the module includes a 1.5-liter equalizing tank 24 to balance pressure fluctuations during adsorption tower switching. The precise switching of the gas path is controlled by the solenoid valve assembly 23. All the above components, including the oil-free reciprocating compressor 21, cooling fan, molecular sieve adsorption tower 22, equalizing tank and solenoid valve assembly 23, are securely mounted on the preset mounting base and threaded holes of the core module base plate 20 by high-strength bolts.

[0044] The material and structure of the core module substrate 20 are crucial for ensuring the overall rigidity of the module, suppressing local resonance, and achieving efficient heat dissipation. In this embodiment, the substrate 20 is made of aluminum-silicon-magnesium cast aluminum alloy and integrally formed by high-pressure die casting. The finished substrate has an overall size of 350 mm × 220 mm and an average thickness of 8 mm. To further improve its structural performance, the bottom surface of the substrate is designed with multiple reinforcing ribs, each 10 mm high and 5 mm wide, arranged in a grid pattern, which significantly improves the substrate's bending and torsional stiffness.

[0045] As a core technical feature of this invention, the multi-point elastic suspension system 4 serves to completely isolate the highly integrated power-air circuit core module 3 from the rest of the machine from mechanical vibration. (Refer to...) Figure 1 and Figure 2 The schematic diagram shows that the system is specifically a four-point elastic suspension system. A suspension fulcrum is provided at each of the four corners of the core module substrate 20. Each suspension fulcrum consists of a specially designed high-damping composite elastomer 30, an upper connecting bolt 31 for connecting to the core module substrate 20, and a lower connecting bolt 32 for fixing to the internal main frame 2.

[0046] Specifically, the high-damping composite elastomer 30 is key to achieving efficient vibration isolation. Its main structure is cylindrical, with an outer diameter of 30 mm and a height of 40 mm. It is not a single material, but a composite of two materials with complementary properties: its matrix is ​​silicone rubber with a Shore A hardness precisely controlled at 45, possessing excellent elasticity and high internal damping characteristics, effectively absorbing and dissipating vibrational energy; a helical steel spring is coaxially embedded on the central axis of the silicone rubber matrix. This spring is made of musical steel wire conforming to ASTM A228 standards, with a wire diameter of 1.5 mm, a spring outer diameter of 15 mm, an effective number of turns of 5, and a free length of 38 mm. In the assembled state, the spring is pre-compressed to 35 mm to provide stable load-bearing capacity and prevent creep during long-term use. This composite structure of silicone rubber and steel spring allows elastomer 30 to combine the large stroke and low-frequency vibration isolation characteristics of a steel spring with the high damping and mid-to-high frequency vibration energy absorption characteristics of rubber materials. Through this design, the low-to-medium frequency mechanical vibrations generated by the operation of the oil-free reciprocating compressor 21, with frequencies mainly concentrated in the range of 25 Hz to 100 Hz, are mostly absorbed and attenuated by the four high-damping composite elastomers 30 when they are transmitted outward from the core module substrate 20. The transmission rate is controlled at an extremely low level, thereby cutting off the main propagation path of solid structure sound radiation to the outside of the machine from the root.

[0047] Furthermore, the internal main frame 2 is the core load-bearing structure of the entire oxygen generator. It is not a traditional chassis, but rather an open spatial frame structure independent of the outer shell assembly 1. This frame is constructed from multiple 6061-T6 high-strength aluminum alloy extruded square tubes with a cross-section of 20 mm × 20 mm and a wall thickness of 2 mm, assembled using M6-specification, 8.8-grade high-strength bolts and custom-made angle bracket connectors. This robust frame structure provides a solid mounting base for the multi-point elastic suspension system 4, with threaded holes machined on its four upper surfaces for mounting the lower connecting bolts 32. Simultaneously, the multi-stage composite exhaust and silencing assembly 5 is mounted on the core module base plate 20, and the control unit 6 is mounted on the internal main frame 2. The technical advantage of this design, which completely separates the load-bearing structure from the enclosed shell, is that even if a very small amount of residual vibration energy is transmitted to the internal main frame 2 through the suspension system, this energy will be confined within the internal frame structure and will not be directly transmitted to the large-area shell assembly 1, which is prone to radiating noise outwards. This achieves a secondary blockage of the vibration transmission path.

[0048] As another core technical feature of the silent design of this invention, the outer shell assembly 1 has undergone special acoustic optimization in material selection and structural design, with the goal of effectively blocking air noise leaking from the inside of the machine and absorbing the vibration of the outer shell sheet itself. Figure 1 As shown, the outer shell assembly 1 is composed of a top plate, a bottom plate, front and rear panels, and side panels. Each panel is not an ordinary single-layer metal plate, but rather employs a constrained damping laminate structure. Specifically, this laminate structure, from the outside in, includes: a 1.2 mm thick SPCC cold-rolled steel plate as the outer panel 10, which provides excellent structural strength, rigidity, and a high-quality surface coating effect; a 1 mm thick special acrylic viscoelastic polymer as the damping core layer 11, which has an extremely high loss factor at room temperature and can effectively convert the bending vibration energy of the plate into negligible heat energy; and a 1.0 mm thick aluminum alloy plate as the inner panel 12. These three layers are tightly bonded together as a whole through a hot-pressing composite process with precise temperature and pressure control. Its working principle is that when the internal sound field or residual vibration excites the outer panel 10 to produce bending vibration, the neutral planes of the inner and outer metal plates do not coincide, resulting in relative shear displacement. This displacement forces the middle viscoelastic damping core layer 11 to undergo severe shear deformation, thereby dissipating vibration energy with extremely high efficiency. This structure significantly improves the sound insulation and anti-resonance capability of the outer shell plate and effectively suppresses the "drum effect".

[0049] As a preferred embodiment, to further reduce the sound energy density within the internal cavity and prevent sound waves from reverberating and amplifying within the cavity, a layer of high-density polyurethane sound-absorbing cotton 13, 25 mm thick and with a density of 80 kg / m³, is fully adhered to all inner surfaces of the outer casing assembly 1 (i.e., the side of the inner panel 12 facing the inside of the machine). To maximize its sound absorption performance, the surface of the high-density polyurethane sound-absorbing cotton 13 facing the inside of the machine is precisely molded into a wave-shaped (commonly known as an egg-box) structure with specific depth and spacing, and a peak-to-valley height difference of 15 mm. This three-dimensional irregular surface morphology greatly increases the effective contact area between the sound-absorbing material and the air, and significantly improves the absorption coefficient for mid-to-high frequency airborne noise above 500 Hz through the diffuse reflection and diffraction effects of sound waves. These mid-to-high frequency noises mainly originate from the airborne noise radiated by the compressor 21 body, cooling fan, and solenoid valve assembly 23 during operation.

[0050] To fundamentally solve the most significant noise source of pressure swing adsorption (PSA) oxygen generators—the intense aerodynamic noise generated by periodic exhaust emissions—this invention specifically designs the aforementioned multi-stage composite exhaust silencing assembly 5. For example... Figure 3 As shown in the cross-sectional structure, this assembly is not a simple resistive or reactive silencer, but a composite structure integrating multiple silencing mechanisms such as expansion silencing, resonant sound absorption, porous dissipation, and tortuous channels. Its overall shape is cylindrical, with a length of 300 mm and an outer diameter of 100 mm. The outer shell is made of high-strength polypropylene (PP) material through injection molding, ensuring airtightness and corrosion resistance. Internally, along the gas flow direction, it is precisely divided into three functionally distinct chambers: a first expansion chamber 40, a porous dissipation section 42, and a second expansion chamber 45.

[0051] Specifically, when the high-pressure, high-velocity exhaust gas (mainly nitrogen) pulse from the exhaust manifold of the solenoid valve assembly 23 enters the silencer assembly, it first reaches the first expansion chamber 40. Due to the sudden expansion of the airflow channel's cross-sectional area here (from a 10 mm diameter hose to a 90 mm diameter chamber), the airflow velocity drops sharply, and the pressure pulsation peak is significantly weakened, achieving the first stage of expansion-based noise reduction. In particular, a Helmholtz resonator 41 structure is integrally formed or additionally assembled on the side wall of this chamber. This resonator consists of a neck tube with an inner diameter of 10 mm and an effective length of 30 mm, and a closed resonant cavity with a volume precisely controlled at 250 cubic centimeters. Based on acoustic calculations, the resonant frequency of this resonator is precisely designed to be around 125 Hz, which corresponds precisely to the dominant low-frequency noise component after Fourier analysis of the oxygen generator exhaust pulse sequence in this embodiment. When noise containing this frequency component passes through, the resonator will resonate strongly, maximizing the absorption of the acoustic energy of this specific narrowband frequency and converting it into heat energy, thus achieving targeted elimination of the most annoying low-frequency "popping" sound.

[0052] After initial noise reduction, the gas continues into the porous dissipation section 42. At the center of this section is a porous metal tube 43 made of 304 stainless steel, with an opening ratio precisely controlled at 30% and a pore diameter of 2 mm. Between the porous metal tube 43 and the outer shell of the porous dissipation section 42, basalt fiber sound-absorbing material 44 with a density of up to 150 kg / m³ is tightly filled. Basalt fiber was chosen because it not only has excellent sound absorption performance but also possesses advantages such as high temperature resistance and good chemical stability. When airflow containing abundant mid-to-high frequency noise components passes through this section, sound waves inevitably penetrate through the small pores in the tube wall and enter the interior of the basalt fiber material. Within the extremely complex labyrinthine pores formed by countless interwoven microfibers, due to the viscosity effect of air and the intense friction between air molecules and the fiber surface, sound energy is efficiently converted into heat energy and dissipated, thus effectively attenuating noise over a wide frequency range.

[0053] Finally, the dissipated and absorbed gas enters the second expansion chamber 45 at the end of the muffler assembly. Inside this chamber, multiple guide baffles 46 are installed at a 45-degree angle. These baffles force the airflow to flow in a tortuous "S"-shaped path instead of directly through the chamber. This design, on the one hand, achieves secondary expansion silencing by further expanding the flow cross-section, thereby reducing residual pressure pulsation; on the other hand, the tortuous channel greatly increases the propagation distance and the number of reflections of the sound waves, with each reflection on the baffle surface leading to further loss of sound energy. At the same time, this structure can also effectively suppress external environmental noise from flowing back into the engine body along the exhaust pipe. After this three-stage physical structure performs a comprehensive treatment of different frequency bands of noise from a shallow to a deep level, the sound pressure level of the exhaust noise is reduced to an extremely low level, and finally released into the surrounding environment in a gentle and quiet manner through the 20 mm diameter exhaust port at the end of the muffler assembly.

[0054] To ensure the integrity and effectiveness of the vibration isolation system constructed by the multi-point elastic suspension system 4, this invention eliminates all possibilities of rigid connections between the power-air circuit core module 3 and other parts of the machine body, and adopts flexible treatment for all connections. Specifically, the air circuit connecting the oxygen production outlet on the power-air circuit core module 3 and the user oxygen intake interface fixed on the outer shell assembly 1 uses a corrugated polytetrafluoroethylene hose with a length of 200 mm and an inner diameter of 8 mm. Similarly, the air circuit connecting the exhaust manifold of the solenoid valve group 23 and the inlet of the multi-stage composite exhaust muffler assembly 5 also uses a flexible hose of the same specifications. This corrugated hose 50 has extremely low bending stiffness and excellent chemical inertness, which can easily absorb the small relative displacements and vibrations that may occur at both ends in three-dimensional space, thereby effectively preventing vibration energy from being transmitted through the typical path of the pipeline. For the more sensitive electrical connections, the wiring harnesses leading from the control unit 6 mounted on the internal main frame 2 to the compressor motor, cooling fan, and solenoid valve assembly 23 on the power-pneumatic core module 3 are designed with a slack allowance of no less than 50 mm, allowing them to hang naturally in a U-shaped arc. This simple approach physically avoids the formation of a "sound bridge" that transmits vibrations due to the wiring harness being stretched, ensuring complete vibration isolation.

[0055] Finally, the silent design of this invention does not stop at the physical structure, but extends to the software control strategy level. The control unit 6 employs a 32-bit ARM Cortex-M4 microprocessor with a main frequency of up to 120 MHz, providing sufficient computing power to execute complex control algorithms. Addressing the problem of drastic step changes in air pressure and flow caused by the rapid opening and closing of solenoid valves in traditional oxygen concentrators, resulting in impact aerodynamic noise, the control unit 6 implements a slow-opening and slow-closing valve drive strategy at the software level. Specifically, the GPIO port of the control unit 6 does not output a simple, either 0 or 1 step switching signal to the solenoid valve drive circuit (usually a MOSFET), but instead outputs a series of precisely modulated high-frequency pulse width modulation (PWM) signals. In the initial stage when the valve needs to open, the duty cycle of the PWM signal does not jump instantaneously from 0% to 100%, but follows a preset S-shaped acceleration curve with a third-order polynomial function, smoothly increasing from 0% to 100% within 100 milliseconds. Similarly, at the final stage of valve closure, the duty cycle follows a similar S-shaped deceleration curve, smoothly decreasing from 100% to 0% within 100 milliseconds. This control method allows the drive current and the electromagnetic force applied to the valve core to build up and disappear gradually, resulting in a smoother valve core displacement process (opening and closing), avoiding violent impacts of the valve core on the valve seat and the resulting sudden changes in air pressure. This control method, which weakens the sound source intensity from the noise generation mechanism, perfectly complements and synergizes with the physical noise reduction structure at the back end, further enhancing the quietness effect.

[0056] Comparative Example 1 provides an oxygen concentrator manufactured using conventional technology. Its core components, such as the compressor, molecular sieve tower, and solenoid valve assembly, are rigidly fixed to a chassis formed by bending a 2mm thick SPCC cold-rolled steel sheet using bolts and shock-absorbing pads. The outer shell is a standard 1.2mm thick SPCC steel sheet structure, without any damping layer or sound-absorbing material. The exhaust port is connected to a simple single-stage expansion silencer filled with a small amount of steel wool. The air path connections use rigid polyurethane tubing. The control unit controls the solenoid valves using a simple step-type switching signal.

[0057] Data Comparison

[0058] To verify the significant advantage of Example 1 in terms of noise reduction performance compared to Comparative Example 1, and to demonstrate that it did not sacrifice core oxygen production performance, rigorous acoustic and performance tests were conducted on both. The test environment was a semi-anechoic chamber with background noise below 20 dBA. The test instruments included a B&K 2250 acoustic analyzer, a multi-channel data acquisition unit, and a high-precision accelerometer. The test results are summarized in the table below:

[0059]

[0060] The data in the table above clearly shows that Embodiment 1 of the present invention, while maintaining almost identical oxygen production flow rate and concentration to Comparative Example 1, achieves a fundamental improvement in noise reduction performance. The overall operating noise is significantly reduced from 59.0 dBA to 38.5 dBA, reaching a library-level quietness. This is mainly attributed to the multi-layered system design. The significant reduction in exhaust port noise (from 75.0 dBA to 45.0 dBA) and the substantial attenuation of noise in the 125 Hz band (reduced by 30 dB) directly demonstrate the superior efficiency of the multi-stage composite exhaust silencing assembly 5, especially the Helmholtz resonator 41. More crucial data lies in the comparison of vibration acceleration: under comparable vibration levels of the vibration source (compressor substrate) (4.5 m / s²),... 2 vs 4.8m / s 2 The vibration acceleration of the outer casing panel of this invention is only 0.15 m / s². 2 The contrast ratio is as high as 3.5 m / s. 2 This quantitative data irrefutably proves that the combination of the multi-point elastic suspension system 4 and the constrained damping laminate shell 1 achieves near-perfect isolation and suppression of solid structure vibration, thereby eliminating structural radiation noise of the machine body.

[0061] In summary, this invention, through the integration of the power-air circuit core module and a series of technical means such as floating suspension, multi-stage composite exhaust silencing, acoustically optimized shell, all-round flexible connection, and software mild control algorithm, constructs a complete systematic quiet solution. It successfully controls the operating noise of the oxygen concentrator to an extremely low level without sacrificing the core oxygen production performance, greatly improving user comfort and the product's market competitiveness.

[0062] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An oxygen concentrator with a silent structure, characterized in that, include: Housing assembly (1); The internal main frame (2) is located inside the housing assembly (1); The power-air circuit core module (3) integrates an oil-free reciprocating compressor (21) for generating compressed air, a molecular sieve adsorption tower (22) for realizing pressure swing adsorption cycle, and a solenoid valve group (23) for controlling the opening and closing of the air circuit. The multi-point elastic suspension system (4) is used to suspend the power-air circuit core module (3) above the internal main frame (2), thereby achieving vibration isolation between the power-air circuit core module (3) and the internal main frame (2). The multi-stage composite exhaust silencer assembly (5) has its inlet end connected to the exhaust pipe of the solenoid valve group (23) in the power-air circuit core module (3) for silencing the exhaust gas generated by the pressure swing adsorption cycle. The control unit (6) is electrically connected to the power-air circuit core module (3) and the multi-stage composite exhaust silencer assembly (5) to coordinate and control the overall operation of the oxygen generator; The interior of the multi-stage composite exhaust muffler assembly (5) is divided into three functional chambers along the gas flow direction. The three functional chambers include: a first expansion chamber (40) that is directly connected to the exhaust pipe of the solenoid valve group (23); a porous dissipation section (42) that is connected to the outlet of the first expansion chamber (40); and a second expansion chamber (45) that is connected to the outlet of the porous dissipation section (42) and has a final exhaust port. On the side wall of the first expansion cavity (40), a Helmholtz resonator (41) is provided. The Helmholtz resonator (41) consists of a neck tube with a preset inner diameter and length and a closed cavity with a preset volume. Its resonant frequency is designed to match the dominant low-frequency component in the pulse noise generated when the solenoid valve assembly (23) exhausts. A porous metal tube (43) is provided at the center of the porous channel dissipation section (42), and basalt fiber sound-absorbing material (44) is filled between the porous metal tube (43) and the outer shell of the porous channel dissipation section (42). The interior of the second expansion chamber (45) is provided with a plurality of flow guide baffles (46) installed at a 45-degree angle. The flow guide baffles (46) force the airflow to form a tortuous "S"-shaped flow path within the second expansion chamber (45).

2. An oxygen concentrator with a silent structure according to claim 1, characterized in that: The power-gas circuit core module (3) also includes a core module base plate (20). The oil-free piston compressor (21), the molecular sieve adsorption tower (22), the solenoid valve group (23), the cooling fan (25) for cooling the compressor (21), and the pressure equalization tank (24) for balancing the gas pressure are all uniformly installed and fixed on the core module base plate (20). The core module base plate (20) is made of cast aluminum alloy material and is integrally die-cast, and its bottom surface is provided with multiple reinforcing ribs distributed in a grid pattern.

3. An oxygen concentrator with a silent structure according to claim 1, characterized in that: The multi-point elastic suspension system (4) is a four-point elastic suspension system, with a suspension fulcrum set at each of the four corners of the power-air circuit core module (3); each suspension fulcrum is composed of a high-damping composite elastomer (30), the upper end face of the high-damping composite elastomer (30) is fixed to the power-air circuit core module (3) by an upper connecting bolt (31), and the lower end face of the high-damping composite elastomer (30) is fixed to the internal main frame (2) by a lower connecting bolt (32); the high-damping composite elastomer (30) has a cylindrical structure, which is composed of a silicone rubber matrix and a spiral steel spring embedded in the center of the silicone rubber matrix.

4. An oxygen concentrator with a silent structure according to claim 1, characterized in that: The outer shell assembly (1) is composed of multiple panels spliced ​​together, and each panel adopts a constrained damping laminate structure; The constrained damping laminate structure comprises, from the outside to the inside, a layer of cold-rolled steel plate as the outer panel (10), a layer of acrylic viscoelastic polymer as the damping core layer (11), and an aluminum alloy plate as the inner panel (12). The outer panel (10), the damping core layer (11), and the inner panel (12) are tightly bonded together by a hot-pressing composite process.

5. An oxygen concentrator with a silent structure according to claim 4, characterized in that: On the inner panel (12) of all panels of the outer casing assembly (1), facing the interior of the oxygen generator, a layer of high-density polyurethane sound-absorbing cotton (13) is covered; and the high-density polyurethane sound-absorbing cotton (13) facing the interior of the oxygen generator is processed into a wave-shaped surface structure with a preset depth and spacing.

6. An oxygen concentrator with a silent structure according to claim 1, characterized in that: The control unit (6) is configured to use a slow-opening and slow-closing valve drive strategy to control the opening and closing of the solenoid valves in the solenoid valve group (23).

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