Shafting sealing structure of ball bearing turbocharger

Abstract

The invention provides a ball bearing turbocharger shafting sealing structure which comprises an impeller, the impeller, a spacer sleeve, an inner ring of a ball bearing and a shaft shoulder of a turbine rotating shaft are fastened through axial pretightening force to form a rotor part, and the rotor part and a sealing sliding block rotate relatively in a non-contact mode to form a sealing gas film with pump pressure difference. The back disc, the outer ring of the ball bearing and the bearing body are fixedly connected to form a stator part; the back disc is connected with the threaded sleeve, the force measuring bolt penetrates through the threaded sleeve and the spring and then is connected with the sealing sliding block, and the spring is always in the state of being compressed by the threaded sleeve and the sealing sliding block. The sealing sliding block slides in the annular track of the back disc, the pre-tightening force and the thickness of the sealing gas film are controlled through the spring and the threaded sleeve, and the pre-tightening force of the spring is measured and set through the force measuring bolt and the threaded sleeve. According to the shaft system sealing structure of the ball bearing turbocharger, the sealing function is achieved, and abrasion of the sealing face is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of turbochargers, and in particular relates to a shaft sealing structure of a ball bearing turbocharger. Background Art

[0002] With the upgrading of my country's emission regulations and the emphasis on energy conservation and emission reduction, the technology of internal combustion engines for vehicles is also developing towards low emissions, low fuel consumption, high reliability and high power density. Turbocharging technology is an effective way to improve vehicle engine efficiency and save energy and reduce consumption. It uses high-temperature exhaust gas to drive the turbine, drive the coaxial compressor impeller to rotate at high speed, and deliver compressed air with higher pressure and density to the engine cylinder, thereby achieving the purpose of increasing the engine output power. The turbocharger is generally in a high-speed operation state during normal operation, with a speed of tens of thousands of revolutions per minute to hundreds of thousands per minute. The normal working speed of the ball bearing supercharger can reach hundreds of thousands per minute. The sealing structure is one of the key structures in the turbocharging system. It is arranged between the compressor, turbine and bearing cavity. It is mainly used to prevent the air on the back of the compressor or the high-temperature gas at the turbine end from entering the bearing cavity and contaminating the engine oil. At the same time, it also prevents the engine oil from entering the compressor end or turbine end to cause "burning oil" or a large amount of oil leakage. The quality of its sealing performance directly affects the working performance, service life and economy of the entire turbocharging system. At present, the seal between the compressor end of the turbocharger and the bearing cavity generally adopts a contact expansion ring seal structure. Its sealing level against oil leakage and adaptability to ultra-high-speed operation conditions make it difficult to meet the strict sealing requirements of turbochargers under different operating conditions such as ultra-high-speed operation, idling operation and frequent start-stop. One side of the turbocharger compressor end seal is the air on the back of the compressor impeller, and the other side is the lubricating oil of the bearing box. When the turbocharger is operating normally, the pressure on the back of the compressor impeller is generally high, which can form a positive pressure difference for the lubricating oil in the bearing cavity, and air may leak into the bearing cavity through the sealing gap. When idling or exhaust braking, the turbocharger speed is generally only 3000-5000r / min. At this time, the pressure on the back of the compressor impeller is low, or even negative pressure. At this time, the oil is easy to leak to the compressor end under the action of the pressure difference. Air film face seal is a non-contact mechanical seal that uses gas or gas-liquid mixed medium as the sealing medium, forms a considerable fluid film bearing capacity through the dynamic and static pressure grooves on the sealing end face to balance the closing force, and then realizes a micron-thick fluid film between the sealing end faces. It has been widely used in rotating equipment such as high-speed centrifugal compressors and centrifugal pumps, and has significant characteristics such as low leakage, low wear and long life. At present, relevant foreign units have tried to use air film face seals between the compressor impeller and the bearing cavity of the turbocharger, and have shown advantages that are difficult to match with other sealing types in terms of adapting to different operating conditions. Summary of the invention

[0003] In view of this, the present invention aims to propose a ball bearing turbocharger shaft system sealing structure to solve the problem of stable sealing of the ball bearing turbocharger under complex working conditions and to increase the service life of the seal.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A ball bearing turbocharger shaft sealing structure comprises a spacer sleeve, a back plate, a force measuring bolt, a turbine shaft, an impeller, a ball bearing and a bearing body. The impeller, the spacer sleeve, the inner ring of the ball bearing and the shoulder of the turbine shaft are fastened by an axial preload force to form a rotor part. The rotor part and the sealing slider form a sealing air film with a pump pressure difference by non-contact relative rotation. The back plate, the outer ring of the ball bearing and the bearing body are fixedly connected to form a stator part. A threaded sleeve is threadedly connected to one side of the back plate. The force measuring bolt passes through the threaded sleeve and is inserted into a spring and is connected to the sealing slider. It has no other degrees of freedom except for moving in the direction of spring expansion and contraction, and the spring is always in a state of being compressed by the threaded sleeve and the sealing slider. The sealing slider slides in the annular track of the back plate, and the preload force and the thickness of the sealing air film are controlled by the spring and the threaded sleeve. The preload force of the spring is measured and set by the force measuring bolt and the threaded sleeve.

[0006] Furthermore, the force measuring bolts pass through the threaded sleeve and are inserted into the spring, and then connected to the sealing slider in a structure evenly distributed along the circumferential direction.

[0007] Furthermore, the sealing slider is provided with a sealing slider sealing surface, and the sealing slider sealing surface is provided with a pump-out type spiral groove.

[0008] Furthermore, the spacer sleeve is also provided with a spacer sleeve sealing surface and a spacer sleeve oil-spinning surface. The spacer sleeve oil-spinning surface is a conical surface, and the spacer sleeve sealing surface is a smooth annular surface perpendicular to the axial direction. The spacer sleeve sealing surface cooperates with the sealing surface of the sealing slider for sealing.

[0009] Furthermore, the sealing slider moves in the slide groove of the back plate through clearance fit, and a rubber ring sealing groove for installing a rubber ring is provided on the outer side of the cylindrical surface of the sealing slider.

[0010] Furthermore, the end surface of the sealing slider is provided with a threaded hole and a spring groove for placing a spring, and the force measuring bolt passes through the threaded sleeve and the spring and is connected to the threaded hole.

[0011] Furthermore, the thread of the force measuring bolt is a fine thread, the nut has a self-locking pattern and the front end has an ear structure for facilitating the connection of a force measuring instrument.

[0012] Furthermore, the outer side of the threaded sleeve is a precision fine-pitch thread, one end face is processed with a screwdriver head groove, and the other end face is processed with a spring seat groove.

[0013] Furthermore, the impeller, the spacer sleeve, and the inner ring of the ball bearing are pressed onto the shoulder of the turbine shaft by screwing a nut into the left end of the impeller.

[0014] Furthermore, the length and stiffness of the spring are determined by calculating the initial preload force of the spring and the compression amount and compression force during operation in combination with the damping effect of the rubber ring.

[0015] Compared with the prior art, the ball bearing turbocharger shaft sealing structure of the present invention has the following advantages:

[0016] (1) With the ball bearing turbocharger shaft sealing structure of the present invention, when the turbocharger stops working along with the engine, the sealing surface of the spacer sleeve and the sealing surface of the sealing slider are in close contact under the preload force, thereby achieving complete sealing.

[0017] (2) With the ball bearing turbocharger shaft sealing structure described in the present invention, when the turbocharger is operating normally, an air film gap is formed between the sealing surface of the spacer sleeve and the sealing surface of the sealing slider, thereby achieving a sealing function and greatly reducing the wear of the sealing surface.

[0018] (3) The ball bearing turbocharger shaft sealing structure and the reasonable design of the force measuring bolt and the threaded sleeve of the present invention enable the spring preload to be conveniently and accurately measured and set in the final stage of assembly of the turbocharger. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It is a cross-sectional schematic diagram of the main structure of the ball bearing turbocharger shaft system sealing structure according to an embodiment of the present invention when the turbocharger rotates at a high speed to form a sealing air film;

[0021] Figure 2 for Figure 1 Enlarged view of part A in the middle.

[0022] Description of reference numerals:

[0023] 1-spacer sleeve, 2-back plate, 3-force measuring bolt, 4-threaded sleeve, 5-spring, 6-sealing slider, 7-rubber ring, 8-sealing slider sealing surface, 9-spacer sleeve sealing surface, 10-spacer sleeve oil throwing surface, 11-turbine shaft, 12-impeller, 13-ball bearing, 14-bearing body. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0027] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0028] A ball bearing turbocharger shaft sealing structure, such as Figure 1 and Figure 2As shown, it includes a spacer sleeve 1, a back plate 2, a force measuring bolt 3, a threaded sleeve 4, a spring 5, a sealing slider 6, a rubber ring 7, a sealing slider sealing surface 8, a spacer sleeve sealing surface 9, a spacer sleeve oil throwing surface 10, a turbine shaft 11, an impeller 12, a ball bearing 13, and a bearing body 14. The impeller 12, the spacer sleeve 1, the inner ring of the ball bearing 13 and the shoulder of the turbine shaft 11 are fastened by an axial preload to form a rotor part, so that the spacer sleeve 1 and the turbine shaft 11 rotate synchronously; the rotor part and the end surface of the sealing slider 6 with a spiral groove rotate relative to each other without contact to form a pump pressure difference. The back plate 2 and the outer ring of the ball bearing 13 are fixedly connected to the bearing body 14 to form a stator part; one side of the back plate 2 is threadedly connected to the threaded sleeve 4, and the force measuring bolt 3 passes through the threaded sleeve 4 and is inserted into the spring 5 and connected to the sealing slider 6. Except for moving in the expansion and contraction direction of the spring 5, there is no other degree of freedom, and the spring 5 is always in a state of being compressed by the threaded sleeve 4 and the sealing slider 6; the sealing slider 6 slides in the annular track of the back plate, and the preload force and the thickness of the sealing air film are controlled by the spring 5 and the threaded sleeve 4. The preload force of the spring 5 can be measured and set by the force measuring bolt 3 and the threaded sleeve 4.

[0029] Preferably, the threaded sleeve 4 is screwed into the back plate 2 via threads.

[0030] Preferably, the force measuring bolt 3 passes through the threaded sleeve 4 and is inserted into the spring 5 and then connected to the sealing slider 6 and is evenly distributed along the circumferential direction.

[0031] In one or more embodiments, a nut is screwed into the left end of the impeller 12 to press the impeller 12, the spacer sleeve 1, and the inner ring of the ball bearing 13 onto the shoulder of the turbine shaft 11, and rotate synchronously with the turbine shaft 11 to form a rotor part.

[0032] In one or more embodiments, the sealing slider 6 is provided with a sealing slider sealing surface 8, and the sealing slider sealing surface 8 is processed with a pump-out type spiral groove.

[0033] In one or more embodiments, the spacer sleeve 1 is also provided with a spacer sleeve sealing surface 9 and a spacer sleeve oil-spinning surface 10. The spacer sleeve oil-spinning surface 10 is a conical surface that can quickly discharge the oil pumped out of the ball bearing 13; the spacer sleeve sealing surface 9 is a smooth annular surface, perpendicular to the axial direction, and the spacer sleeve sealing surface 9 cooperates with the sealing surface 8 of the sealing slider to play a sealing role.

[0034] The sealing slider 6 can move in the slide groove of the back plate 2 through clearance fit. A rubber ring sealing groove is provided on the outer side of the cylindrical surface of the sealing slider 6 for installing the rubber ring 7.

[0035] The end surface of the sealing slide block 6 is provided with a threaded hole and a spring groove for placing a spring, and the force measuring bolt 3 passes through the threaded sleeve 4 and the spring 5 and is connected to the threaded hole.

[0036] The thread of the force measuring bolt 3 is a fine thread, the nut has a self-locking pattern and the front end has an ear structure for connecting the force measuring instrument. A groove is left on the back plate 2 for the nut of the force measuring bolt 3.

[0037] The outer side of the threaded sleeve 4 is a precision fine pitch thread, one end face is processed with a screwdriver head groove, and the other end face is processed with a spring seat groove.

[0038] The length and stiffness of the spring 5 are determined by designing and calculating the initial preload of the spring 5 and the compression amount and compression force during operation in combination with the damping effect of the rubber ring 7 .

[0039] The working principle of a ball bearing turbocharger shaft sealing structure is:

[0040] When the other parts shown in the figure have been assembled but the impeller 2 has not been assembled, the preload force of the sealing slider 6 and the spacer sleeve 1 is adjusted: first, the force measuring bolt 3 is loosened appropriately until it cannot be pushed to the right by hand and the end face of the force measuring bolt 3 is separated from the end face of the threaded sleeve 4 (that is, the sealing surface 8 of the sealing slider is pressed against the sealing surface 9 of the spacer sleeve); then, several pairs of symmetrical force measuring bolts 3 are connected to the force measuring equipment, and the tensile force received by all the force measuring bolts 3 is made into a horizontal leftward resultant force through the tooling design, which is the preload force of the sealing surface; if the preload force is not within the design value range (through the margin given by the previous engineering design, the preload force will not be greater than the maximum value of the design value range), the sealing surface preload force needs to be adjusted; unscrew the force measuring bolt 3, and use a screwdriver to evenly screw it into all the threaded sleeves 4 to a certain depth (which can be simply calculated based on the spring stiffness and the thread pitch), and the preload force adjustment can be completed; finally, screw the force measuring bolt 3 in again to measure the preload force of the sealing surface until the preload force meets the requirements.

[0041] When the supercharger is not rotating and there is lubricating oil in the cavity of the bearing body 14, the sealing surface 8 of the sealing slider and the sealing surface 9 of the spacer sleeve are pressed tightly under the preload force of the spring 5, preventing the lubricating oil from flowing into the side of the impeller 12 from the gap between the spacer sleeve 1 and the back plate 2. When the supercharger rotates, the sealing surface 8 of the sealing slider is processed with a pump-out type spiral groove, and a stable fluid film of a certain thickness is formed after relative rotation with the sealing surface 9 of the spacer sleeve, thereby preventing the air in the back cavity of the impeller 12 and the lubricating oil in the cavity of the bearing body 14 from flowing into each other.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A ball bearing turbocharger shaft sealing structure, characterized in that: It includes a spacer sleeve, a back plate, a force measuring bolt, a turbine shaft, an impeller, a ball bearing and a bearing body. The impeller, the spacer sleeve, the inner ring of the ball bearing and the shoulder of the turbine shaft are fastened by axial preload to form a rotor part. The rotor part and the sealing slider form a sealing air film with a pump pressure difference through non-contact relative rotation. The back plate and the outer ring of the ball bearing are fixed to the bearing body to form a stator part. The back plate is threadedly connected to a threaded sleeve. The force measuring bolt passes through the threaded sleeve and is inserted into a spring to be connected to the sealing slider. It has no other degrees of freedom except moving in the direction of spring expansion and contraction, and the spring is always in a state of being compressed by the threaded sleeve and the sealing slider. The sealing slider slides in the annular track of the back plate, and the preload and the thickness of the sealing air film are controlled by the spring and the threaded sleeve. The preload of the spring is measured and set by the force measuring bolt and the threaded sleeve.

2. A ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The force measuring bolts pass through the threaded sleeve and are inserted into the spring, and then the structures connected with the sealing slider are evenly distributed along the circumferential direction.

3. The ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The sealing slider is provided with a sealing slider sealing surface, and the sealing slider sealing surface is provided with a pump-out type spiral groove.

4. A ball bearing turbocharger shaft sealing structure according to claim 3, characterized in that: The spacer sleeve is also provided with a spacer sleeve sealing surface and a spacer sleeve oil-spinning surface. The spacer sleeve oil-spinning surface is a conical surface, and the spacer sleeve sealing surface is a smooth annular surface perpendicular to the axial direction. The spacer sleeve sealing surface cooperates with the sealing surface of the sealing slider for sealing.

5. The ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The sealing slider moves in the slide groove of the back plate through clearance fit, and a rubber ring sealing groove for installing the rubber ring is arranged on the outer side of the cylindrical surface of the sealing slider.

6. A ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The end surface of the sealing slide block is provided with a threaded hole and a spring groove for placing a spring, and the force measuring bolt passes through the threaded sleeve and the spring and is connected with the threaded hole.

7. The ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The thread of the force measuring bolt is a fine pitch thread, the nut has a self-locking pattern and an ear structure at the front end for easy connection of the force measuring instrument.

8. The ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The outer side of the threaded sleeve is a precision fine pitch thread, one end face is processed with a screwdriver head groove, and the other end face is processed with a spring seat groove.

9. The ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The impeller, the spacer sleeve and the inner ring of the ball bearing are pressed onto the shoulder of the turbine shaft by screwing a nut into the left end of the impeller.

10. The ball bearing turbocharger shaft sealing structure according to claim 1, characterized in that: The length and stiffness of the spring are determined by calculating the initial preload of the spring, the compression amount and the compression force during operation, and combining the damping effect of the rubber ring.

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