Shaft structure of self-lubricating turbocharger ball bearings

Abstract

This invention relates to the field of shaft lubrication technology, and discloses a shaft structure for a self-lubricating turbocharger ball bearing. The turbocharger includes a bearing housing, a compressor volute, an oil seal cap, a turbine housing, a rotor shaft, an impeller, and a backplate assembly. The backplate assembly includes a backplate that mates with the compressor volute. The turbine housing is connected to the compressor volute. The air inlet of the compressor volute is embedded in the outer periphery of the bearing housing. An oil reservoir is formed between the oil seal cap, the bearing housing, and the compressor volute, and the pressure within the oil reservoir is balanced with the ambient pressure. The shaft structure includes a sleeve portion located at the central shaft of the bearing housing. The rotor shaft and impeller are assembled and inserted into the sleeve portion, forming a bearing housing cavity between the rotor shaft and the inner wall of the sleeve portion. A bearing assembly is provided on the shaft section of the rotor shaft inserted into the sleeve portion. A channel for lubricating oil delivery is provided between the bearing housing cavity and the oil reservoir. By setting up the oil reservoir and opening the channel, the slight negative pressure environment of the bearing housing cavity ensures that lubricating oil is automatically delivered along the channel to lubricate the shaft structure.

Description

Technical Field

[0001] This invention belongs to the field of shaft lubrication technology, specifically relating to a shaft structure for a self-lubricating turbocharger ball bearing. Background Technology

[0002] Currently, the bearing lubrication systems of turbocharger products both domestically and internationally primarily employ external oil supply lubrication technology. Turbocharger shaft systems using dual floating bearings, semi-floating bearings, and ball bearings utilize engine lubrication for lubrication and heat dissipation. The turbocharger lubricating oil inlet connects to the engine's main oil passage to form the inlet pipeline; the turbocharger lubricating oil return pipeline connects to the engine's oil pan to form the return pipeline. The turbocharger inlet and return pipelines are specialized components, requiring specific engine design requirements for sealing, high pressure resistance, and corrosion resistance. Sufficient space must be allocated within the overall engine layout to facilitate the installation and normal operation of the turbocharger inlet and return pipelines.

[0003] If the engine exhaust temperature exceeds 800°C, the turbocharger bearing housing will employ a cooling water channel structure to prevent the high temperature of the engine exhaust gas from radiating or conducting into the bearing housing, thus ensuring the required operating temperature of the bearing. The arrangement of the cooling water channels increases the overall size of the turbocharger bearing housing. Additionally, the engine structure layout requires the addition of dedicated inlet and outlet water pipes for the turbocharger.

[0004] Turbochargers use engine oil, which can become contaminated with worn metal particles from piston wear, carbon deposits from the engine, and corrosion from the inner walls of the lubrication lines. This can cause turbocharger bearings to become scratched, abnormally worn, seize, sinter, or the sealing system to fail, ultimately leading to significant oil leakage and severely impacting engine safety. Currently, engine oil leakage is the primary failure mode for turbochargers and a major technical challenge in the turbocharger industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a shaft structure for a self-lubricating turbocharger ball bearing that does not require engine lubricating oil and can ensure the reliability of turbocharger shaft system operation.

[0006] The technical solution of the present invention is: a shaft system structure for a self-lubricating turbocharger ball bearing. The turbocharger includes a bearing housing, a compressor volute, an oil seal cap, a turbine housing, a rotor shaft, an impeller, and a back plate assembly. The back plate assembly includes a back plate that mates with the compressor volute. The turbine housing is connected to the compressor volute. The outer periphery of the bearing housing is embedded in the air inlet of the compressor volute. An oil reservoir is formed between the oil seal cap, the bearing housing, and the compressor volute. The pressure in the oil reservoir is balanced with the ambient pressure. The shaft system structure includes a sleeve portion located at the central shaft of the bearing housing. The rotor shaft and the impeller are assembled and inserted into the sleeve portion to form a bearing housing cavity between the rotor shaft and the inner wall of the sleeve portion. A bearing assembly is provided on the shaft section of the rotor shaft inserted into the sleeve portion. A channel for lubricating oil delivery is provided between the bearing housing cavity and the oil reservoir.

[0007] A further technical solution of the present invention is: the bearing assembly includes a first ball bearing and a second ball bearing distributed at both ends of the sleeve portion. The first ball bearing is located close to the impeller. An outer ring spring for adjusting the clearance of the first ball bearing and the second ball bearing is sleeved on the rotor shaft. A stop is provided inside the sleeve portion for the installation of the outer ring spring. The outer ring spring abuts against the outer ring of the second ball bearing.

[0008] A further technical solution of the present invention is: the bearing housing cavity is provided with a bearing outer ring sleeve at the outer ring of the second ball bearing, and the bearing outer ring sleeve is clearance-fitted with the outer ring of the second ball bearing.

[0009] A further technical solution of the present invention is: the number of channels is two, which supply lubricating oil to the first ball bearing and the second ball bearing respectively.

[0010] A further technical solution of the present invention is: the channel is an oil pipe.

[0011] A further technical solution of the present invention is: the oil sealing cap is provided with a breathable oil injection nozzle.

[0012] A further technical solution of the present invention is: it also includes a heat shield assembly disposed between the back plate assembly and the turbine housing, the heat shield assembly including a heat shield covering the end face of the back plate, and a heat shield pad sandwiched between the heat shield and the turbine housing.

[0013] A further technical solution of the present invention is that a heat insulation pad is provided between the back plate and the heat insulation cover.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1) By setting up an oil reservoir and opening a channel between the bearing housing cavity and the oil reservoir, the micro-negative pressure environment formed in the bearing housing cavity ensures that the lubricating oil is automatically and smoothly delivered from the channel, achieving excellent lubrication effect for the shaft structure. This eliminates the traditional solution of using engine lubricating oil for lubrication and avoids the risks of wear, jamming, and damage to the shaft structure caused by aging oil.

[0016] 2) After the lubricating oil is drawn into the bearing housing cavity due to negative pressure, it will form an oil mist under the high-speed rotation of the bearing and shaft, continuously filling the bearing housing cavity. While fully lubricating the bearing, it can also play an excellent heat dissipation role.

[0017] 3) The inner rotor shaft of the sleeve section has a double bearing support structure. The outer ring spring of the bearing can provide a suitable axial preload, which solves the problem of radial and axial load of the bearing in the turbocharger shaft system structure, making the shaft system structure run more smoothly and reliably.

[0018] The detailed structure of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the turbocharger described in Example 1. Detailed Implementation

[0020] Example 1

[0021] like Figure 1The turbocharger shown has a self-lubricating ball bearing shaft system and includes a bearing housing 11, a compressor volute 12, an oil seal cap 13, a turbine housing 14, a rotor shaft 15, an impeller 16, and a backplate assembly. The compressor volute 12 and the turbine housing 14 are connected as a whole by a clamp 17. The outer periphery of the bearing housing 11 is riveted (or embedded) to the air inlet of the compressor volute 12. The oil seal cap 13 is fitted onto the outer periphery of the end of the bearing housing 11. The oil seal cap 13, the bearing housing 11, and the compressor are connected. An oil reservoir 2 is formed between the volute 12, the compressor volute 12, and the bearing housing 11. O-rings are installed at the contact surfaces of the oil sealing cap 13 and the compressor volute 12, and at the contact surfaces of the oil sealing cap 13 and the bearing housing 11, to ensure the sealing effect of the oil reservoir 2. The oil sealing cap 13 is equipped with a ventilated oil injection nozzle 3, through which lubricating oil can be injected into the oil reservoir 2. This ventilated oil injection nozzle 3 ensures that the pressure inside the oil reservoir 2 is balanced with the ambient pressure. The shaft system includes a sleeve located at the central shaft of the bearing housing. After the rotor shaft 15 and impeller 16 are assembled and inserted into the sleeve part 111, a bearing housing cavity is formed between the rotor shaft 15 and the inner wall of the sleeve part 111. An oil chamber plug 4 is provided at the end of the sleeve part 111 near the oil sealing cap 13 to form a closed end. At the other end of the bearing housing cavity, the sleeve part 111 forms a labyrinth air passage cooperation structure with the impeller 16. This structure can form an air passage between the sleeve part 111 and the impeller 16. The rotor shaft 15 is provided with a bearing assembly on the shaft section of the inserted sleeve part. There is a channel 5 for lubricating oil to be transported between the bearing housing cavity and the oil storage cavity 2. When the impeller 16 is working, a negative pressure will be generated at the impeller inlet. This air passage will generate a slight negative pressure environment in the bearing housing cavity, so that the lubricating oil in the oil storage cavity 2 will automatically enter the channel 5 and be sucked into the bearing housing cavity. The channel 5 is preferably an oil pipe (or an oil core). The oil pipe is sealed to the wall of the bearing housing to ensure that the lubricating oil in the oil storage cavity is transported quickly and smoothly.

[0022] By using a self-contained oil reservoir, the micro-negative pressure environment of the bearing housing cavity allows lubricating oil to be drawn into the bearing housing cavity during the operation of the turbocharger shaft system for bearing lubrication. This eliminates the traditional method of using engine lubricating oil and avoids the risks of wear, jamming, and damage to the shaft system caused by aging oil. This self-lubricating shaft system fully ensures the reliability of the turbocharger.

[0023] The bearing assembly includes a first ball bearing 61 and a second ball bearing 62 distributed at both ends of the sleeve portion 111. The first ball bearing 61 is located near the impeller 16. A bearing outer ring spring 63 for adjusting the clearance of the first ball bearing and the second ball bearing is sleeved on the rotor shaft 15. A stop is provided in the sleeve portion 111 for the bearing outer ring spring 63 to be installed. The bearing outer ring spring 63 abuts against the outer ring of the second ball bearing 62. The bearing housing cavity is also provided with a bearing outer ring sleeve 64 at the outer ring of the second ball bearing 62. The bearing outer ring sleeve 64 is clearance-fitted with the outer ring of the second ball bearing 62. In addition, a rubber outer ring sleeve damping ring 65 is embedded in the bearing housing cavity. The outer ring sleeve damping ring 65 is located on the outer circumference of the bearing outer ring sleeve 64. The outer ring sleeve damping ring 65 can limit the bearing outer ring sleeve 64 through the rubber elasticity and absorb the bearing working excitation force transmitted by the bearing outer ring sleeve, prevent the superposition of vibration excitation, and ensure the overall reliable and stable operation of the shaft system structure.

[0024] One end of the bearing outer ring spring 63 is positioned at the inner stop of the sleeve portion 111, and the other end pushes the outer ring of the second ball bearing 62, causing the first ball bearing 61, the second ball bearing 62, and the rotor shaft 15 to move together, pre-pressing the first ball bearing 61 and the second ball bearing 62 to the assembly position, and keeping the two bearings in a zero-clearance working state. When the bearing balls are working, they will generate heat and expand in volume, but because the axial limit is spring force thrust, rather than the rigid positioning in the conventional technical state, a 0.015mm (preferably 0.015mm) fit clearance must be maintained between the inner and outer rings and balls of the first ball bearing and the second ball bearing. At this time, the bearing can overcome the spring force and automatically adjust the clearance to a zero state, so as not to interfere with the bearing and cause jamming, while reducing the bearing working noise.

[0025] In this embodiment, the shaft system is a dual-bearing thrust-resistant structure. The first and second ball bearings are coaxial angular contact ball bearings (the balls can be made of ceramic or other temperature- and wear-resistant materials). The inner rings of the bearings are integrated with the rotor shaft. The outer ring of the first ball bearing 61 is fixed in the bearing housing cavity for axial positioning. Under the action of axial force and elasticity, the outer ring of the second ball bearing 62 drives the rotor shaft assembly towards the impeller inlet position through the balls. The bearings at both ends are bidirectionally self-locking and limiting, which solves the problem of radial and axial bearing load in the shaft system structure, making the shaft system run smoothly and reliably. Moreover, the bearing clearance will automatically correct to zero in any working state, which can effectively reduce the operating noise of the bearing. Since there are two bearings, in order to achieve rapid and sufficient lubrication of the shaft system structure, two oil pipes are also set. One extends into the space formed between the oil chamber plug 4 and the second ball bearing 62, and the other extends into the bearing housing cavity space near the first ball bearing. The two oil pipes mainly supply lubricating oil to the first and second ball bearings, respectively.

[0026] The back plate assembly includes a back plate 181 that mates with the compressor volute 12. A back plate sleeve 182 is pressed into the center of the back plate. A heat shield assembly is also provided between the back plate assembly and the turbine housing 14. The heat shield assembly includes a heat shield 191 that covers the end face of the back plate 181. A sealing sleeve 192 is provided at the part of the heat shield 191 through which the rotor shaft 15 passes. A heat shield 193 is provided between the back plate 181 and the heat shield 191. A heat shield is also provided between the back plate sleeve and the heat shield. In addition, a heat shield is also sandwiched between the heat shield and the turbine housing.

[0027] The impeller is fixed to the rotor shaft by a spline nut and rotates coaxially with the turbine to perform work. The thread direction of the spline nut is opposite to the working direction of the impeller. Tightening the spline nut presses the impeller firmly against the shoulder surface of the rotor shaft. Alternatively, the impeller can be fixed by interfering with the inner wall of the spline nut to form a single unit with the rotor shaft, and by engaging the spline groove on the end face of the spline nut with the end face of the impeller.

[0028] Driven by the exhaust gas from the engine, the rotor shaft drives the coaxial impeller to rotate at high speed. The impeller pumps air in, creating a negative pressure band at its inlet, which generates a pressure difference in the bearing housing cavity, causing a siphon effect. The air pressure at the end of the oil pipe inside the bearing housing cavity is lower than atmospheric pressure, while the pressure at the end of the oil pipe in the oil reservoir is the same as the ambient air pressure. At this time, lubricating oil enters the bearing housing cavity under the pumping action of the negative pressure band. Due to the high-speed rotation of the rotor shaft and bearings, the lubricating oil droplets are atomized through evaporation. After entering the bearing housing cavity from the oil pipe, the lubricating oil becomes an oil mist, filling the bearing housing cavity. The oil mist can adhere to all parts of the first and second ball bearings, ensuring proper operation. By lubricating the surfaces of the components, the bearing's operating friction resistance is reduced. Simultaneously, the heat generated by the bearing is transferred to the sleeve wall. The outer wall of the sleeve is cooled by active air cooling. A series of bearing housings are arranged at the impeller inlet, utilizing the low-temperature ambient air drawn in by the impeller to cool the shaft structure. The greater the impeller's workload, the more heat is generated by the bearing. Simultaneously, the greater the airflow through the sleeve, the more heat is carried away, resulting in a more significant cooling effect. The airflow through the sleeve removes heat, achieving the required lubrication and heat dissipation for the bearing. Furthermore, the cooling of the shaft structure does not cause a significant temperature rise in the intake air, thus avoiding any performance loss in the compressor. The required oil mist concentration in the bearing housing cavity can be achieved by adjusting the fit clearance and structure between the bearing housing and the impeller nose.

[0029] The aforementioned shaft system structure simplifies the overall structure of the turbocharger, reduces the limitations imposed by bearings on the overall structure, and effectively prevents exhaust gas from leaking into the compressor end and isolates the turbine's heat from radiating to the compressor.

[0030] This invention is not limited to the specific structure or connection method described above. Any shaft system structure that has the same or similar concept as this technical solution falls within the protection scope of this invention.

Claims

1. A shaft system structure for a self-lubricating turbocharger ball bearing, characterized in that: The turbocharger includes a bearing housing (11), a compressor volute (12), an oil cover (13), a turbine housing (14), a rotor shaft (15), an impeller (16), and a back plate assembly. The back plate assembly includes a back plate (181) that mates with the compressor volute (12). The turbine housing (14) is connected to the compressor volute (12). The bearing housing (11) is embedded in the air inlet of the compressor volute (12) on its outer periphery. An oil reservoir (2) is formed between the oil cover (13), the bearing housing (11), and the compressor volute (12). A ventilated oil injection nozzle (3) is provided on the oil cover (13). The pressure in the oil reservoir is balanced with the ambient pressure. The shaft system includes a sleeve (111) located at the center shaft of the bearing housing (11). The rotor shaft (15) and the impeller (16) are assembled and inserted into the sleeve. (111) and form a bearing housing cavity between the sleeve part and the inner wall of the sleeve part. The rotor shaft (15) is provided with a bearing assembly on the shaft section inserted into the sleeve part. There is a channel (5) for lubricating oil to be transported between the bearing housing cavity and the oil storage cavity (2). The sleeve part (111) forms a labyrinth air passage cooperation structure with the impeller (16) at the other end of the bearing housing cavity. The labyrinth air passage cooperation structure forms an air passage between the sleeve part (111) and the impeller (16). When the impeller (16) is working, a negative pressure is generated at the impeller inlet. The air passage generates a micro negative pressure environment in the bearing housing cavity, which causes the lubricating oil in the oil storage cavity (2) to automatically enter the channel (5) and be sucked into the bearing housing cavity. After the lubricating oil enters the bearing housing cavity, it becomes an oil mist that fills the bearing housing cavity. The oil mist adheres to all parts of the bearing assembly.

2. A turbocharger, characterized in that: The shaft system structure of the self-lubricating turbocharger ball bearing as described in claim 1 is provided. The bearing assembly includes a first ball bearing (61) and a second ball bearing (62) distributed at both ends of the sleeve portion (111). The first ball bearing (61) is located close to the impeller (16). A bearing outer ring spring (63) for adjusting the clearance of the first ball bearing and the second ball bearing is sleeved on the rotor shaft (15). A stop is provided in the sleeve portion (111) for the bearing outer ring spring to be installed. The bearing outer ring spring (63) abuts against the outer ring of the second ball bearing (62).

3. The turbocharger according to claim 2, characterized in that: The bearing housing cavity is also provided with a bearing outer ring sleeve (64) at the outer ring of the second ball bearing (62), and the bearing outer ring sleeve is clearance-fitted with the outer ring of the second ball bearing.

4. The turbocharger according to claim 2, characterized in that: There are two channels (5), which supply lubricating oil to the first ball bearing and the second ball bearing respectively.

5. The turbocharger according to claim 4, characterized in that: Channel (5) is an oil pipe.

6. The turbocharger according to claim 2, characterized in that: It also includes a heat shield assembly disposed between the back plate assembly and the turbine housing, the heat shield assembly including a heat shield (191) covering the end face of the back plate (181), and a heat shield pad sandwiched between the heat shield (191) and the turbine housing (14).

7. The turbocharger according to claim 2, characterized in that: A heat insulation pad is installed between the back plate and the heat insulation cover.

Images