A two-stage coaxial high-pressure ratio rotating system with cooling and vibration suppression

Abstract

This invention discloses a two-stage coaxial high-pressure ratio rotating system with cooling and vibration suppression. One end of the turbine is fixed to the rotor shaft. The rotor shaft passes through a bearing and a second-stage compressor impeller. The rotor shaft is fixed to the bearing and the second-stage compressor impeller. The first-stage compressor impeller is fixed to the rotor shaft and is located upstream of the second-stage compressor impeller, with both impellers arranged in the same direction. The bearing has oil passages for absorbing heat from the turbine end and for compressing an oil film to absorb vibrations generated during rotation. A thrust assembly is located between the bearing and the second-stage compressor impeller. The thrust assembly includes a thrust ring and a thrust plate. The thrust ring is fitted onto the rotor shaft and fixed to it. A groove is provided on the circumferential surface of the thrust ring, and a portion of the thrust plate is located within the groove. A gap for accommodating lubricating oil is left between the thrust plate and the groove. This invention combines excellent heat dissipation capacity and excellent dynamic stability.

Description

Technical Field

[0001] This utility model relates to a two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression. Background Technology

[0002] To meet the urgent demands of modern high-performance internal combustion engines, aero-piston engines, and high-altitude power equipment for high power density and high-altitude power recovery, achieving a high boost ratio has become the core objective of turbocharging technology development. The design of sequentially installing the front and rear compressor impellers within a single turbocharger housing integrates two-stage compression functions into a compact unit, significantly simplifying external piping and system layout. It boasts advantages such as compact structure, small size, and high integration, making it an ideal technical direction for addressing the complexity of two-stage series designs. However, this design, pursuing both high boost ratio and high integration, faces two interrelated and extremely challenging technical bottlenecks in engineering practice: extreme thermal loads and complex rotor dynamics problems.

[0003] To achieve a high boost ratio, the rotor must operate stably at extremely high speeds (typically exceeding 100,000 rpm). Integrating two compressor impellers and one (or more) turbine impellers onto a single rotor creates a complex, flexible rotor system with uneven mass distribution and a long axial span. This structure is highly susceptible to inducing harmful vibration modes such as first- and second-order bending of the compressor impellers during high-speed rotation. This vibration not only generates harsh noise and accelerates bearing wear, but more dangerously, it can cause the high-speed rotating impeller to rub against the stationary volute, leading to instantaneous failure. Especially under transient engine conditions, severe airflow fluctuations further disrupt rotor balance, exacerbating the vibration risk. Existing conventional bearing support solutions are insufficient to effectively suppress the dynamic instability of such a complex rotor system.

[0004] Based on the above, while existing single-unit sequential two-stage turbochargers have made progress in structural integration, their shortcomings in thermal management and rotor dynamics have become key obstacles restricting their performance and widespread application when pursuing the core goal of "high pressure ratio." Therefore, there is an urgent need for an innovative rotor system design that can deeply integrate efficient and precise cooling technology with advanced dynamic vibration suppression technology to work synergistically on the rotor system. Utility Model Content

[0005] This invention provides a two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression, which combines excellent heat dissipation capacity and excellent dynamic stability.

[0006] A two-stage coaxial high-pressure ratio rotating system with cooling and vibration suppression includes a rotor shaft, a turbine, a bearing, a first-stage compressor impeller, and a second-stage compressor impeller. The turbine is fixed to one end of the rotor shaft. The rotor shaft passes through the bearing and the second-stage compressor impeller. The rotor shaft is fixed to the bearing and the second-stage compressor impeller. The first-stage compressor impeller is fixed to the rotor shaft. The first-stage compressor impeller is located upstream of the second-stage compressor impeller, and the first-stage compressor impeller and the second-stage compressor impeller are arranged in the same direction. The bearing is provided with an oil passage for absorbing heat from the vortex end and for compressing the bearing oil film to absorb vibrations generated by rotation.

[0007] It also includes a thrust assembly for bearing the axial forces of the first-stage compressor impeller and the second-stage compressor impeller. The thrust assembly is located between the bearing and the second-stage compressor impeller. The thrust assembly includes a thrust ring and a thrust plate. The thrust ring is sleeved on the rotor shaft and fixed to the rotor shaft. The circumferential surface of the thrust ring is provided with an annular groove. A portion of the thrust plate is located in the annular groove. A gap for accommodating lubricating oil is left between the thrust plate and the annular groove.

[0008] This invention's rotating system employs a two-stage compressor structure arranged sequentially within a single turbocharger. The first and second-stage compressor impellers are installed axially along the rotor. Air undergoes initial compression first through the first-stage compressor impeller, then flows into the second-stage compressor impeller for further pressurization. This two-stage continuous compression significantly improves the overall pressure ratio. Compared to traditional two-stage tandem turbocharger systems, the first and second-stage compressor impellers in this invention are driven by the same rotor shaft, highly integrating the compression function into a single rotor unit. This significantly reduces external connecting pipes, support structures, and space occupation, achieving system miniaturization and high integration. This integrated solution not only optimizes aerodynamic performance but also simplifies assembly and maintenance, making it suitable for space- and weight-sensitive aerospace power units. It provides a compact and reliable solution for achieving high-efficiency, high-pressure-ratio compression. In addition, an oil circuit is set in the structure. When the rotor vibrates, the outer ring of the bearing makes an eccentric movement in the oil chamber, squeezing the oil film. The viscous resistance of the oil film generates a strong damping force, which absorbs the vibration energy to suppress the vibration. Since the entire bearing is filled with lubricating oil, when the rotor is working, the heat on the turbine is transferred through the rotor shaft, while the lubricating oil cools the rotor shaft, thereby preventing the heat from being transferred to the second-stage compressor impeller. Attached Figure Description

[0009] Figure 1 This is a cross-sectional view of a two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression.

[0010] Figure 2 This is an assembly drawing of the rotor shaft and the turbine.

[0011] Figure 3 This is a cross-sectional view of the bearing.

[0012] Figure 4 This is a structural diagram of the first-stage compressor impeller.

[0013] Figure 5 This is the structure diagram of the push component.

[0014] Figure 6 This is a structural diagram of the sealing assembly.

[0015] The markings in the attached diagram are: rotor shaft 1, clearance section 1a, guide section 1b, turbine 2, groove 2a, bearing 3, annular oil groove 3a, oil supply hole 3b, oil outlet hole 3c, first stage compressor impeller 4, first bore section 4a, second bore section 4b, and third bore section.

[0016] 4c, second-stage compressor impeller 5, thrust assembly A, thrust ring 6, annular groove 6a, thrust plate 7, sealing assembly B, shaft seal 8, first annular groove 8a, first hole 8b, sealing cover 9, groove 9a, annular insertion part 9b, ejection channel 10, bearing housing C, lubricating oil inlet channel C1, fluid medium transition cavity C2, output hole C3. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] like Figures 1 to 6 As shown in the figure, a two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression in this embodiment includes a rotor shaft 1, a turbine 2, a bearing 3, a first-stage compressor impeller 4, a second-stage compressor impeller 5, and a thrust assembly A for bearing the axial forces of the first-stage compressor impeller 4 and the second-stage compressor impeller 5. The rotor shaft 1, turbine 2, bearing 3, first-stage compressor impeller 4, second-stage compressor impeller 5, and thrust assembly A constitute the rotor. The components and their relationships are described in detail below.

[0019] The turbine 2 is fixed to one end of the rotor shaft 1. The turbine 2 and rotor shaft 1 are preferably fixed by welding. Grooves 2a are provided on the axial end faces of both the rotor shaft 1 and the turbine 2. Grooves 2a offer the following advantages: First, grooves 2a reduce the material volume at the welding interface, allowing heat generated during friction welding to dissipate more easily through the hollow channel, preventing excessively high local temperatures. This reduces material performance degradation caused by high temperatures (such as decreased strength and coarse grains). Second, it reduces flash and material loss: Friction welding generates "flash" (excess metal) due to plastic deformation of the interface. The design of grooves 2a allows the plastic metal at the interface to flow more easily into the grooves 2a, rather than overflowing outwards to form a large amount of flash. This reduces the workload of subsequent flash cleaning and also reduces the loss of valuable materials (such as titanium alloys and high-temperature alloys). Third, it optimizes pressure distribution and improves welding strength: The hollow structure allows the welding pressure to be more concentrated in the annular area of ​​the interface, avoiding the problem of pressure dispersion towards the center in solid structures. This ensures sufficient plastic deformation of the interface metal and achieves a tight bond, thereby improving the strength of the welded joint. Fourth, it reduces equipment load and improves process stability: The design of groove 2a reduces the friction area and material inertia at the welding interface, resulting in lower required friction torque and axial pressure. This reduces the power consumption and load on the welding equipment, extending its lifespan. Simultaneously, the smaller heat input and more controllable plastic flow reduce defects such as incomplete penetration and cracks during welding, improving process stability. Furthermore, the hollow design of groove 2a reduces the heat input to turbine 2, lowers the temperature of rotor shaft 1, and reduces the bearing thermal load during use.

[0020] The rotor shaft 1 passes through the bearing 3 and the second-stage compressor impeller 5. The rotor shaft 1 is fixed to the bearing 3 and the second-stage compressor impeller 5. In this embodiment, a clearance part 1a is provided between the rotor shaft 1 and the second-stage compressor impeller 5 to prevent the rotor shaft 1 from deforming too much when it passes the critical speed. In this embodiment, the clearance part 1a is an annular groove provided on the circumference of the rotor shaft 1. The clearance part 1a has the following advantages: First, since the rotor shaft 1, turbine 2, bearing 3, first-stage compressor impeller 4 and second-stage compressor impeller 5 are assembled to form a rotor, when the rotor passes the critical speed, the rotor shaft 1 deforms into an "arch" shape. The clearance part 1a can prevent the rotor shaft from rubbing against the hole wall of the second-stage compressor impeller 5, ensuring safe passage through the critical speed. Secondly, since the rotor shaft 1 and the second-stage compressor impeller 5 are assembled by press fitting, the presence of the clearance part 1a during the press fitting process can reduce the press fitting resistance, avoid the sudden increase in press fitting force due to the excessive initial contact area, make the press fitting force more stable, reduce equipment load fluctuations, and improve the consistency of the assembly process.

[0021] In this embodiment, a guide section 1b is provided on the rotor shaft 1 to mate with the hole on the second-stage compressor impeller 5. The rotor shaft 1 and the hole on the second-stage compressor impeller 5 are in an interference fit. The guide section 1b has the following advantages: First, it guides and centers the rotor shaft, avoiding jamming: During interference fit, the clearance between the rotor shaft 1 and the hole on the second-stage compressor impeller 5 is extremely small. Without a guide, the rotor shaft 1 is prone to "skewed contact" with the hole of the second-stage compressor impeller 5, resulting in jamming and inability to press in smoothly. The guide section (usually a small taper or cylindrical transition section) can first be inserted into the hole to achieve preliminary centering, ensuring coaxiality during subsequent pressing. Second, it protects the mating surfaces and reduces damage: The working surfaces of the shaft / hole in an interference fit require high precision. Directly forcing the fit can easily cause chipping of the hole opening, denting of the shaft end, or scratching of the mating surfaces. After setting the guide section 1b on the rotor shaft 1, interference fit is facilitated, which can significantly reduce the assembly difficulty, protect the precision of the parts, and improve the reliability of the assembly.

[0022] The bearing 3 is provided with an oil passage for absorbing heat from the vortex end and for compressing an oil film in the bearing 3 to absorb vibrations generated by rotation. The oil passage on the bearing 3 includes an annular oil groove 3a, an oil supply hole 3b, and an oil outlet hole 3c provided on the outer ring of the bearing 3, with the oil supply hole 3b communicating with the annular oil groove 3a. Bearing 3 is mounted on bearing housing C, which has an oil chamber filled with lubricating oil. The outer ring of bearing 3 has an annular oil groove 3a, an oil supply hole 3b, and an oil outlet hole 3c. Lubricating oil enters the interior of bearing 3 through the annular oil groove 3a and the oil supply hole 3b. Under the action of lubricating oil, bearing 3 forms a floating bearing, that is, an oil-floating bearing. After lubrication, the oil flows out from the oil outlet hole 3c. There is an oil film between the outer ring of bearing 3 and bearing housing. When the rotor vibrates, the outer ring of bearing 3 makes an eccentric movement in the oil chamber, squeezing the oil film. The viscous resistance of the oil film generates a strong damping force. That is, the high-pressure oil film can counteract the eccentricity of the rotor, allowing the rotor to return to the center, thereby absorbing vibration energy and suppressing vibration. In addition, since the entire interior of bearing 3 is filled with lubricating oil, when the rotor is working, the heat on turbine 2 is transferred through rotor shaft 1, and the lubricating oil cools rotor shaft 1, thereby preventing heat from being transferred to the second-stage compressor impeller 5.

[0023] In this embodiment, the bearing 3 is preferably a ball bearing. The core advantages of ball bearings are significantly reduced frictional resistance, improved response speed, and superior high-speed stability, making them suitable for the high-speed and rapid power feedback requirements of turbocharged systems. Their specific advantages can be summarized as follows: First, faster response speed (reduced turbo lag): The rolling friction coefficient of ball bearings is much lower than that of traditional sliding bearings, resulting in lower starting resistance and allowing the turbocharger to reach its operating speed more quickly, significantly reducing turbo lag. Power output is more rapid and responsive when the accelerator is pressed. Second, lower frictional loss and higher efficiency: The low frictional characteristics reduce energy loss in bearing transmission, allowing more exhaust gas energy to be converted into turbine driving force, indirectly improving the turbocharger's boost efficiency and contributing to stronger engine power output or reduced fuel consumption. Third, stronger stability at high speeds: The structural design of ball bearings allows for more precise radial and axial runout control at high speeds (some turbocharger turbine speeds can reach 100,000 rpm or higher), resulting in better operational stability than sliding bearings. This reduces the risk of friction between the turbine and the housing, making them suitable for the demanding operating conditions of high-performance engines. Fourth, it has a relatively low dependence on lubricating oil: Compared with sliding bearings, which rely on oil film for lubrication and heat dissipation, ball bearings are easier to meet in terms of lubrication. They are more resistant to failure when the supply of lubricating oil fluctuates briefly (such as in the early stage of cold start), which indirectly extends their service life.

[0024] The first-stage compressor impeller 4 is fixed to the rotor shaft 1. The first-stage compressor impeller 4 has a blind hole, comprising a first section 4a, a second section 4b, and a third section 4c. The second section 4b is located between the first section 4a and the third section 4c. The rotor shaft 1 is threaded to the second section 4b and has an interference fit with the third section 4c. The head of the rotor shaft 1 extends into the first section 4a and has an interference fit with it. In a two-stage supercharging system, the first-stage compressor impeller 4 needs to handle a large flow rate of air. The blind hole on the first-stage compressor impeller 4 makes it a blind-hole impeller. The robust structure of the blind-hole impeller can better withstand the resulting loads. The disc structure without axially penetrating holes provides extremely high bending and torsional stiffness, effectively resisting the enormous centrifugal force generated during high-speed rotation and preventing plastic deformation or fracture of the impeller under high pressure ratio, high speed, and high stress. Since the rotor shaft 1 is threaded to the second hole section 4b, and the first hole section 4a and the third hole section 4c are interference-fitted with the rotor shaft 1, this connection structure can accurately achieve axial positioning and load transmission, adapting to the working conditions of high-speed rotation of the pressure roller.

[0025] The first-stage compressor impeller 4 is located upstream of the second-stage compressor impeller 5, and the first-stage compressor impeller 4 and the second-stage compressor impeller 5 are arranged in the same direction. This same-direction arrangement means that the first head 40 of the first-stage compressor impeller 4 and the second head 50 of the second-stage compressor impeller 5 face the same direction. For example... Figure 1The first head 40 and the second head 50 both face the left end of the entire rotating system.

[0026] In a single-stage turbocharger, only one compressor impeller generates axial force. However, in a two-stage system, due to the use of a first-stage compressor impeller 4 and a second-stage compressor impeller 5 (i.e., two compressor impellers), there are two superimposed axial forces, making the total axial force on the compressor side much greater than in a single-stage system. Furthermore, the air compressed by the first-stage compressor impeller 4 is then compressed again by the second-stage compressor impeller 5. With an increased pressure ratio, the pressure difference between the two sides of each impeller stage becomes greater, resulting in a larger axial force. Therefore, in this embodiment, a ball bearing is used as bearing 3, and a thrust assembly A is also provided. Both bearing 3 and thrust assembly A can counteract the axial force.

[0027] In this embodiment, the thrust assembly A is located between the bearing 3 and the second-stage compressor impeller 5. The thrust assembly includes a thrust ring 6 and a thrust plate 7. The thrust ring 6 is sleeved on the rotor shaft 1 and fixed to the rotor shaft 1. An annular groove 6a is provided on the circumferential surface of the thrust ring 6. A portion of the thrust plate 7 is located in the annular groove 6a, and a gap for accommodating lubricating oil is left between the thrust plate 7 and the annular groove 6a. The thrust plate 7 is fixed to the bearing housing C. During operation, the thrust ring 6 rotates with the rotor shaft 1, while the thrust plate 7 remains stationary. Lubricating oil enters the gap between the thrust plate 7 and the annular groove 6a and forms an oil film to lubricate the thrust ring 6 and the thrust plate 7. Since the thrust plate 7 is fixed to the bearing housing C, the axial force generated by the first-stage compressor impeller 4 and the second-stage compressor impeller 5 during operation is loaded onto the thrust plate 7 and then transmitted from the thrust plate 7 to the bearing housing C, which remains stationary, thereby overcoming the influence of the axial force on the rotor.

[0028] This embodiment also includes a sealing assembly B for ejecting the fluid medium, which is air and oil. Since the lubricating oil overflows after entering the thrust ring 6 and thrust plate 7 via the oil passage, the gas from the first-stage compressor impeller 4, the second-stage compressor impeller 5, and the turbine 22 enters the bearing housing C, forming a mixture of air and oil. To prevent gas from leaking into the second-stage compressor impeller 5, a sealing assembly B is installed on the rotor shaft 1. The sealing assembly B is fitted onto and fixed to the rotor shaft 1, and is located between the second-stage compressor impeller 5 and the thrust assembly.

[0029] The sealing assembly B includes a shaft seal 8 and a sealing cover 9. The shaft seal 8 is fitted onto the rotor shaft 1 and fixed to the rotor shaft 1. The shaft seal 8 is provided with a first annular groove 8a and a first hole 8b for discharging fluid medium. The first hole 8b communicates with the first annular groove 8a. The sealing cover 9 is fitted onto the shaft seal 8 and cooperates with the shaft seal 8. One end of the sealing cover 9 is provided with a groove 9a and an annular insertion part 9b. The annular insertion part 9b cooperates with the first annular groove 8a. When the sealing assembly B rotates, the sealing cover 9, the annular insertion part 9b, and the shaft seal 8 form a channel 10 through which fluid medium is discharging.

[0030] The bearing housing C has a lubricating oil inlet channel C1, a fluid medium transition cavity C2, and an outlet hole C3. The lubricating oil inlet channel C1 is fitted with the bearing 3, the sealing assembly B is fitted with the fluid medium transition cavity C2, and the outlet hole C3 is connected to the fluid medium transition cavity C2.

[0031] When the rotor shaft 1 rotates, the sealing assembly B rotates with the rotor shaft 1. Gas and lubricating oil enter the groove 9a and then enter the ejection channel 10. Under the action of centrifugal force, they are ejected from the first hole 8b into the fluid medium output chamber C2 of the bearing housing C, and then output to the outside of the bearing housing C through the output hole C3 on the bearing housing C.

Claims

1. A two-stage coaxial high-pressure ratio rotating system with cooling and vibration suppression, comprising a rotor shaft (1), a turbine (2), a bearing (3), a first-stage compressor impeller (4), and a second-stage compressor impeller (5), wherein the turbine (2) is fixed to one end of the rotor shaft (1), the rotor shaft (1) passes through the bearing (3) and the second-stage compressor impeller (5), the rotor shaft (1) is fixed to the bearing (3) and the second-stage compressor impeller (5), the first-stage compressor impeller (4) is fixed to the rotor shaft (1), the first-stage compressor impeller (4) is located upstream of the second-stage compressor impeller (5), and the first-stage compressor impeller (4) and the second-stage compressor impeller (5) are arranged in the same direction, characterized in that, The bearing (3) is provided with an oil passage for absorbing heat from the vortex end and for squeezing the oil film of the bearing (3) to absorb the vibration generated by rotation; It also includes a thrust assembly (A) for bearing the axial force of the first-stage compressor impeller (4) and the second-stage compressor impeller (5). The thrust assembly (A) is located between the bearing (3) and the second-stage compressor impeller (5). The thrust assembly includes a thrust ring (6) and a thrust plate (7). The thrust ring (6) is sleeved on the rotor shaft (1) and fixed to the rotor shaft (1). The circumferential surface of the thrust ring (6) is provided with an annular groove. A part of the thrust plate (7) is located in the annular groove. A gap for accommodating lubricating oil is left between the thrust plate and the annular groove.

2. The two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression according to claim 1, characterized in that, It also includes a sealing assembly (B) that ejects the fluid medium. The sealing assembly (B) is fitted onto the rotor shaft (1) and fixed to the rotor shaft (1). The sealing assembly (B) is located between the second-stage compressor impeller (5) and the thrust assembly.

3. A two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression as described in claim 2, characterized in that, The sealing assembly (B) includes a shaft seal (8) and a sealing cover (9). The shaft seal (8) is fitted onto the rotor shaft (1) and fixed to the rotor shaft (1). The shaft seal (8) is provided with a first annular groove (8a) and a first hole (8b) for ejecting fluid medium. The first hole (8b) communicates with the first annular groove (8a). The sealing cover (9) is fitted onto the shaft seal (8) and fixed to the shaft seal (8). One end of the sealing cover (9) is provided with a groove (9a) and an annular insertion part (9b). The annular insertion part (9b) cooperates with the first annular groove (8a). The sealing cover (9), the annular insertion part (9b), and the shaft seal (8) form an ejection channel (10) for the fluid medium when the sealing assembly (B) rotates.

4. A two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression according to any one of claims 1 to 3, characterized in that, An air vent (1a) is provided between the rotor shaft (1) and the impeller (5) of the second-stage compressor to prevent excessive deformation of the rotor shaft (1) when it passes the critical speed.

5. A two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression according to any one of claims 1 to 3, characterized in that, A guide section (1b) is provided on the rotor shaft (1) to mate with a hole on the impeller (5) of the second stage compressor.

6. A two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression according to any one of claims 1 to 3, characterized in that, The oil passage on the bearing (3) includes an annular oil groove (3a), an oil supply hole (3b), and an oil outlet hole (3c) provided on the outer ring of the bearing (3). The oil supply hole (3b) is connected to the annular oil groove (3a).

7. A two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression according to any one of claims 1 to 3, characterized in that, The bearing (3) is a ball bearing.

8. A two-stage coaxial high-pressure ratio rotation system with cooling and vibration suppression according to any one of claims 1 to 3, characterized in that, The first-stage compressor impeller (4) is provided with a blind hole, which includes a first hole section (4a), a second hole section (4b), and a third hole section (4c). The second hole section (4b) is located between the first hole section (4a) and the third hole section (4c). The rotor shaft (1) is threadedly connected to the second hole section (4b), and the rotor shaft (1) is interference-fitted with the third hole section (4c).

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