A porous two-phase bearing and rotor support structure for a micro-turbojet engine

Abstract

The present invention discloses a porous two-phase bearing and a rotor support structure of a micro-sized turbojet engine, including an impeller, a central shaft, a turbine, a front bearing and a rear bearing; the impeller is fixed to the front end of the central shaft, the turbine is fixed to the rear end of the central shaft, the front bearing is installed at the front end of the central shaft and behind the impeller, and the rear bearing is installed at the rear end of the central shaft and in front of the turbine. The porous characteristics of the bearing material itself and the affinity of the material with oil are fully utilized, and the cooling and lubrication of the bearing, the shaft sleeve and the central shaft are completed by the lubricating oil and ambient air of the bearing itself. There is no need to equip a separate bearing lubrication pipeline, and the engine oil supply system has a simple structure; the porous bearing is composed of a bearing inner ring and a bearing outer ring, and has no ball structure. Compared with traditional rolling bearings, the radial size is smaller and the cost is lower. Compressible adjustment rings, elastic gaskets and other aspects compensate for displacement and vibration, effectively improving the bearing life and the working stability and reliability of the rotor system.

Description

Technical Field

[0001] The present invention relates to the field of engines, and more specifically, to a porous two-phase bearing of a micro-sized turbojet engine and a rotor support structure thereof. Background Art

[0002] Compared with conventional engines, micro turbojet engines are smaller in size, lighter in weight, and have a higher thrust-to-weight ratio. They are widely used in micro unmanned target drones, reconnaissance aircraft, and model aircraft. They can also provide power for tactical cruise missiles. At the same time, since refueling is faster and more convenient than charging, they can also be used as portable energy for future field operations.

[0003] The bearing lubrication system is an indispensable and important part of the engine system. During the engine startup, operation and shutdown process, it fully ensures the safe and reliable operation of the engine rotor and prevents it from being damaged due to friction overheating, which may cause the engine to malfunction.

[0004] Most existing micro-turbojet engines utilize rolling bearing lubrication systems. While rolling bearings offer excellent starting performance and can maintain a relatively high load capacity at moderate speeds, they also have significant drawbacks that have limited the development of turbojet engines. Firstly, the presence of rolling bearings necessitates the addition of separate lubrication lines to the engine system, increasing system complexity. Secondly, because rolling bearings typically consist of an inner ring, an outer ring, and balls, the presence of the balls results in a relatively large radial dimension. Secondly, rolling bearings have low vibration damping capabilities, significantly reducing bearing life when the engine operates at high speeds. Finally, ball bearing lubrication systems are costly. Summary of the Invention

[0005] To overcome the problems of conventional rolling bearing lubrication in engines, resulting in complex oil circuit structures, large dimensions, and short service life, the present invention provides a porous two-phase bearing for a micro-turbojet engine and a rotor support structure thereof. The porous two-phase bearing is supported by the bearing itself and is impregnated with lubricating oil, achieving self-lubrication and cooling. It has a simple structure and provides a vibration-absorbing effect.

[0006] To achieve this object, the present invention provides a porous two-phase bearing for a micro-turbojet engine and a rotor support structure thereof, comprising an impeller, a front bearing, a rear bearing, a center shaft and a turbine; the impeller is fixed to the front end of the center shaft, the turbine is fixed to the rear end of the center shaft, the front and rear ends of the center shaft are both provided with steps, the front bearing is sleeved on the center shaft and arranged in the step near the front end of the center shaft, the rear bearing is sleeved on the center shaft and arranged in the step near the rear end of the center shaft, the front bearing and the rear bearing are both configured as porous bearings, the porous bearing comprises an outer ring and an inner ring, the outer ring is sleeved outside the inner ring, and both the outer ring and the inner ring are porous structures.

[0007] In a preferred technical solution of the present invention, a shaft sleeve is provided outside the central shaft, a double-layer sealing ring is provided between the front bearing and the shaft sleeve, and a single-layer sealing ring is provided between the rear bearing and the shaft sleeve.

[0008] In a preferred technical solution of the present invention, a plurality of elastic gaskets are installed at the rear end of the front bearing, and a single elastic gasket is installed at the front end of the rear bearing.

[0009] In a preferred technical solution of the present invention, an oil storage tank is provided on the inner side of the outer ring.

[0010] In a preferred technical solution of the present invention, the front end of the central shaft is connected to a front locking nut, which abuts against the impeller, and the rear end of the central shaft is connected to a rear locking nut, which abuts against the turbine.

[0011] In a preferred technical solution of the present invention, a diffuser is provided outside the shaft sleeve, and a casing is provided outside the diffuser.

[0012] In a preferred technical solution of the present invention, a flame tube is provided in the casing, the flame tube is sleeved outside the shaft sleeve, the output end of the flame tube is connected to a guide, and the guide extends to one side of the turbine.

[0013] In a preferred technical solution of the present invention, a compressible adjustment ring is further sleeved on the central shaft, and the compressible adjustment ring abuts against the rear end of the rear bearing.

[0014] In a preferred technical solution of the present invention, an outer sleeve is fixed to the front end of the casing, the inner side of the outer sleeve constitutes an air inlet duct, and the impeller extends into the air inlet duct.

[0015] In a preferred technical solution of the present invention, a tail nozzle is connected to the rear end of the casing, and the tail nozzle is communicated with the casing.

[0016] The beneficial effects of the present invention are:

[0017] The present invention provides a porous two-phase bearing and rotor support structure for a micro-sized turbojet engine. These bearings utilize the inherent porosity of the bearing material and its affinity for oil. The bearings, sleeves, and center shaft are cooled and lubricated using the bearing's own lubricating oil and ambient air, eliminating the need for separate bearing lubrication lines and simplifying the engine's oil supply system. The porous bearings, consisting of an inner and outer ring without a ball bearing structure, offer smaller radial dimensions and lower cost compared to traditional rolling bearings. Compressible adjustment rings and elastic gaskets compensate for displacement and vibration, effectively improving the rotor system's operational stability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1Schematic diagram of the structure of a porous two-phase bearing and a rotor support structure of a micro-turbojet engine provided by a specific embodiment of the present invention;

[0019] Figure 2 yes Figure 1 A in the middle is an enlarged structural diagram;

[0020] Figure 3 yes Figure 1 The enlarged structural diagram at B in the middle;

[0021] Figure 4 yes Figure 1 Schematic diagram of air flow direction when the middle rotor system is in operation;

[0022] Figure 5 This is a schematic diagram of the direction of oil seepage from the porous bearing pores when the rotor system is in operation;

[0023] Figure 6 This is a schematic diagram of the oil return direction of the porous bearing pores when the rotor system is in operation;

[0024] Figure 7 yes Figure 1 Cross-sectional view of the front and rear bearings;

[0025] Figure 8 It is a schematic diagram of the three-dimensional structure of the front and rear bearings.

[0026] In the picture:

[0027] 1-impeller, 2-diffuser, 3-sleeve, 41-front bearing, 42-rear bearing, 43-outer ring, 44-inner ring, 45-oil reservoir, 46-bearing clearance, 5-center shaft, 6-compressible adjusting ring, 7-turbine, 8-front locking nut, 9-rear locking nut, 10-casing, 11-outer jacket, 12-inlet duct, 13-flame tube, 14-guide, 15-tail nozzle, 16-elastic gasket. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0029] like Figure 1-8As shown, the embodiment provides a micro-turbojet engine porous two-phase bearing and its rotor support structure, including an impeller 1, a front bearing 41, a rear bearing 42, a central shaft 5 and a turbine 7; the impeller 1 is fixed to the front end of the central shaft 5, the turbine 7 is fixed to the rear end of the central shaft 5, and steps are provided at the front and rear of the central shaft 5. The front bearing 41 is sleeved on the central shaft 5 and is arranged in the step close to the front end of the central shaft 5. The rear bearing 42 is sleeved on the central shaft 5 and is arranged in the step close to the rear end of the central shaft 5. The front bearing 41 and the rear bearing 42 are both configured as porous bearings. The porous bearing includes an outer ring 43 and an inner ring 44. The outer ring 43 is sleeved outside the inner ring 44, and the outer ring 43 and the inner ring 44 are both porous structures.

[0030] When the rotor system of the present invention is applied to a micro-turbojet engine, a sleeve 3 is mounted on the outer surface of the central shaft 5. A diffuser 2 is mounted on the outer surface of the sleeve 3, near the impeller 1. A casing 10 is located outside the diffuser 2. A sleeve 11 is fixed to the front end of the casing 10. The inner surface of the sleeve 11 forms an air inlet 12, into which the impeller 1 extends. The rear end of the casing 10 is connected to a tail nozzle 15. A flame tube 13 is located outside the sleeve 3 and inside the casing 10. The output end of the flame tube 13 is connected to a guide 14, which extends to one side of the turbine 7.

[0031] When the central shaft 5 is not rotating, lubricating oil fills the pores between the outer and inner rings 43 and 44 of the bearing. During engine operation, the central shaft 5 rotates. The bearing is lubricated by a high-temperature-resistant lubricant coating sprayed on the contact surfaces of the inner and outer rings 44 and 43. Furthermore, when the rotor system experiences slight vibrations, lubricating oil within the oil reservoir 45 flows immediately into the bearing gap 46, ensuring effective lubrication of the bearing gap 46. High-pressure air passes through the diffuser 2 and into the gap formed between the back of the impeller 1 and the diffuser 2. Under pressure, the air passes through the front bearing 41. Because the bearing in this embodiment is porous, it provides a strong flow-distributing effect on the air passing through it, enabling uniform cooling of the bearing in all directions. After passing through the front bearing 41, the air continues to flow toward the rear bearing 42, cooling the inner wall of the sleeve 3 and the central shaft 5 in the process. Finally, it flows into the rear bearing 42, providing uniform cooling of the rear bearing 42 in all directions. This achieves cooling of the entire bearing system and the central shaft 5.

[0032] When the rotor is in operation, as the bearing temperature rises, the lubricating oil automatically enters the bearing gap 46 because the volume expansion coefficient of oil is greater than that of metal, thereby achieving lubrication and cooling of the bearing. The lubricating oil in the oil storage tank 45 will also partially flow into the bearing gap 46, thereby compensating for the lubricating oil that overflows through the pores due to long-term high-speed operation of the bearing or excessive temperature rise.

[0033] When the rotor stops rotating, the front bearing 41 and the rear bearing 42 cool down, the pores are restored, and the lubricating oil returns to the pores of the bearings themselves. At this time, the lubricating oil returning to the internal pores of the bearings is composed of two parts. One part is the lubricating oil that seeps through the porous bearings when the rotor is in working condition, and the other part is the lubricating oil that flows into the bearing gap 46 from the oil storage tank 45 when the engine is started or compensated. This design effectively realizes the renewal of the cooling lubricating oil inside the bearings themselves, greatly improving the bearing life and the working reliability of the rotor system.

[0034] Furthermore, a double-layer sealing ring is provided between the front bearing 41 and the sleeve 3, and a single-layer sealing ring is provided between the rear bearing 42 and the sleeve 3. The sealing ring can prevent the lubricating oil from flowing back and out of the concave platform too quickly, resulting in low lubrication efficiency.

[0035] Furthermore, a plurality of elastic washers 16 are mounted on the rear end of the front bearing 41, and a single elastic washer 16 is mounted on the front end of the rear bearing 42. The elastic washers 16 on the front bearing 41 are used to compensate for axial displacement between the center shaft 5 and the front bearing 41. The elastic washers 16 on the rear bearing 42 are also used to compensate for axial position and prevent bearing displacement.

[0036] Furthermore, an oil reservoir 45 is provided on the inner side of the outer ring 43. The oil reservoir 45 is filled with lubricating oil. When the rotor vibrates slightly, the lubricating oil in the oil reservoir 45 immediately flows into the bearing gap 46 to ensure lubrication.

[0037] Furthermore, the front end of the central shaft 5 is connected to a front locking nut 8, which abuts against the impeller 1, and the rear end of the central shaft 5 is connected to a rear locking nut 9, which abuts against the turbine 7. The front locking nut 8 presses the front end of the impeller 1 against the central shaft 5, while the rear locking nut 9 abuts against the turbine 7. This achieves axial fixation of the entire rotor system and prevents changes in the axial position of the rotor system due to vibration during operation.

[0038] Furthermore, the output end of the flame tube 13 is connected to a guide 14, which extends to one side of the turbine 7. The guide 14 can guide the high-temperature combustion gas output by the flame tube 13 to the turbine 7, so that the turbine 7 can fully receive the high-temperature combustion gas and rotate, thereby improving the rotation efficiency.

[0039] Furthermore, a compressible adjustment ring 6 is sleeved on the central shaft 5 and abuts against the rear end of the rear bearing 42. The compressible adjustment ring 6 is fixed to the rear end of the rear bearing 42. This ring ensures that the rear bearing 42 is always compressed and absorbs vibrations generated by the rotor's rotation, ensuring stable operation of the rotor system.

[0040] Furthermore, the air in the rear bearing 42 is discharged and mixed with the combustion gas at the front end of the turbine 7 and discharged through the tail nozzle 15 to generate thrust.

[0041] Other technologies of this embodiment adopt existing technologies.

[0042] The present invention is described through preferred embodiments. Those skilled in the art will appreciate that various modifications or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. The present invention is not limited to the specific embodiments disclosed herein; other embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A porous two-phase bearing and rotor support structure for a micro-sized turbojet engine, characterized in that: It comprises an impeller (1), a front bearing (41), a rear bearing (42), a central shaft (5) and a turbine (7); The impeller (1) is fixed to the front end of the central shaft (5), the turbine (7) is fixed to the rear end of the central shaft (5), steps are provided at the front and rear of the central shaft (5), the front bearing (41) is sleeved on the central shaft (5) and arranged in the step close to the front end of the central shaft (5), the rear bearing (42) is sleeved on the central shaft (5) and arranged in the step close to the rear end of the central shaft (5), the front bearing (41) and the rear bearing (42) are both configured as porous bearings, the porous bearings include an outer ring (43) and an inner ring (44), the outer ring (43) is sleeved outside the inner ring (44), and the outer ring (43) and the inner ring (44) are both porous structures; The central shaft (5) is provided with a shaft sleeve (3) on its outer sleeve, a double-layer sealing ring is provided between the front bearing (41) and the shaft sleeve (3), and a single-layer sealing ring is provided between the rear bearing (42) and the shaft sleeve (3); A diffuser (2) is arranged outside the shaft sleeve (3), and a casing (10) is arranged outside the diffuser (2); A flame tube (13) is arranged in the casing (10), the flame tube (13) is sleeved outside the shaft sleeve (3), the output end of the flame tube (13) is connected to a guide (14), and the guide (14) extends to one side of the turbine (7); A jacket (11) is also fixed to the front end of the casing (10), the inner side of the jacket (11) forms an air inlet (12), and the impeller (1) extends into the air inlet (12); The rear end of the casing (10) is connected with a tail nozzle (15), and the tail nozzle (15) is in communication with the casing (10); An oil storage groove (45) is provided on the inner side of the outer ring (43).

2. A micro-sized turbojet engine porous two-phase bearing and rotor support structure thereof according to claim 1, characterized in that: A plurality of elastic washers (16) are installed at the rear end of the front bearing (41), and a single elastic washers (16) is installed at the front end of the rear bearing (42).

3. The porous two-phase bearing and rotor support structure of a micro-sized turbojet engine according to claim 1, characterized in that: The front end of the central shaft (5) is connected to a front locking nut (8), which abuts against the impeller (1); the rear end of the central shaft (5) is connected to a rear locking nut (9), which abuts against the turbine (7).

4. The porous two-phase bearing and rotor support structure of a micro-sized turbojet engine according to claim 1, characterized in that: The central shaft (5) is also sleeved with a compressible adjustment ring (6), which abuts against the rear end of the rear bearing (42).

Images