JPS632013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bearing structure for a turbocharger.

Conventionally, floating radial bearings have been employed in turbochargers to support the rotating shaft of the turbocharger. This floating bearing has a hollow cylindrical shape, and a plurality of lubricating oil circulation holes connecting the inner circumferential wall surface and the outer circumferential wall surface are formed inside the bearing. Furthermore, a lubricating oil supply hole opened on the outer peripheral wall surface of the floating bearing is formed in the turbocharger housing to supply lubricating oil to the floating bearing,
The open end of this lubricating oil supply hole is a groove with a semicircular cross section to form a lubricating oil reservoir. As mentioned above, floating bearings are formed with lubricating oil circulation holes, but if these lubricating oil circulation holes are simply drilled, burrs formed around the openings of the lubricating oil circulation holes will be removed. Frictional contact occurs with the bearing bearing surface of the turbocharger housing, resulting in the problem of seizure of the floating bearing. In addition, as mentioned above, a groove with a semicircular cross section is formed on the housing bearing support surface at the open end of the lubricating oil supply hole, but if burrs remain on the periphery of this groove, this burr may float. Frictional contact occurs with the outer peripheral wall surface of the bearing, resulting in a similar problem in that the floating bearing seizes. Therefore, in conventional floating bearings, in order to prevent seizure, the area around the opening of the lubricating oil flow hole of the floating bearing and the periphery of the semicircular cross-sectional groove of the turbocharger housing are chamfered. As a result, the processing of the floating bearing portion becomes extremely complicated, leading to a rise in manufacturing costs. Furthermore, even if the circumferential edge of the semicircular groove of the turbocharger housing is chamfered, the outer circumferential wall of the bearing will be damaged because the corner of the circumferential edge of the semicircular groove will come into contact with the outer circumferential wall of the floating bearing. There's a problem.

An object of the present invention is to provide a floating bearing structure that has no risk of damage to the outer circumferential wall of the bearing and is easy to manufacture.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, 1 is an engine body, 2 is an intake manifold, 3 is an exhaust manifold, 4 is a fuel injection valve, and 5 is a turbocharger. The turbocharger 5 includes a center housing 6, a turbine housing 8 fixed to one end of the center housing 6 by a band 7, and a compressor housing 10 fixed to the other end of the center housing 6 by a snap spring 9. , a rotating shaft 11 rotatably inserted into the center housing 6, a turbine wheel 12 integrally formed on one end of the rotating shaft 11, and fixed to the other end of the rotating shaft 11 with a nut 13. An impeller 14 is provided. Inside the compressor housing 10, there is an air inlet 15 and a vaneless differential user 16.
A scroll-shaped air discharge chamber 17 is formed,
This air discharge chamber 17 is connected to the intake manifold 2 via an air duct 18. On the other hand, the turbine housing 8 has a scroll-shaped exhaust gas inflow chamber 19.
, a turbine nozzle 20 , and an exhaust gas outlet 21
The exhaust gas inflow chamber 19 is equipped with an exhaust duct 2.
2 to an exhaust manifold 3. During engine operation, the compressed air in the air discharge chamber 17 is compressed by the rotational movement of the impeller 14 and flows into the air duct 1.
8 into the intake manifold 2.
Next, fuel is injected from the fuel injection valve 4 into the air fed into the intake manifold 2, and the air-fuel mixture thus formed is supplied into the engine cylinders.
On the other hand, the exhaust gas discharged from the engine cylinder is sent into the exhaust gas inflow chamber 19 through the exhaust duct 22, and then the exhaust gas in the exhaust gas inflow chamber 19 is ejected from the turbine nozzle 20 and rotates into the turbine wheel 12. After applying the force, the exhaust gas is discharged from the exhaust gas outlet 21.

As shown in FIG. 1, the rotating shaft 11 has a central shaft portion 11a, a large diameter shaft portion 11b, and a small diameter shaft portion 1.
1c, and a sealing piston ring 23 is provided between the large diameter shaft portion 11b and the center housing 6.
is inserted. A pair of floating radial bearings 25 are arranged at a distance from each other in a cylindrical bearing support hole 24 formed through the center housing 6. 11 is rotatably supported. On the other hand, the small diameter shaft portion 11 of the rotating shaft 11
A thrust bearing 26 is provided on c to support the rotating shaft 11 in the axial direction. This thrust bearing 26 includes a runner member 28 integrally formed with a pair of disc-shaped runners 27, and each of these runners 2.
7 and a fixed bearing plate 29 inserted between the runners 27 with a slight interval therebetween. The runner member 28 is fixed to the small diameter shaft portion 11c via a spacer 30 and the impeller 14 with a nut 13, while the fixed bearing plate 29 is fixed to the center housing 6 via a partition member 31 with a snap ring 32. Further, a mechanical seal structure 33 is provided between the partition wall member 31 and the spacer 30. On the other hand, a lubricating oil inlet 34 and a lubricating oil distribution hole 35 are formed in the center housing 6, and the lubricating oil inlet 34 is connected to a lubricating oil supply pump (not shown). A lubricating oil outflow hole 36 extending parallel to the axis of the rotating shaft 11 is formed in the fixed bearing plate 29 , and the lubricating oil outflow hole 36 is connected to the lubricating oil distribution hole 35 via a lubricating oil hole 37 . Therefore, the lubricating oil injected from the lubricating oil inlet 34 flows out from the lubricating oil outlet hole 36 through the lubricating oil hole 37 between the liner 27 and the fixed bearing plate 29, and thus the thrust bearing 26 is lubricated. It will be. On the other hand, a pair of lubricant supply holes 38 are further formed in the center housing 6 and extend from the lubricant distribution hole 35 toward the floating bearing 25.
The floating bearing 25 is lubricated by the lubricating oil flowing out from the floating bearing 25.

Referring to FIG. 2, a pair of ring grooves 39 are formed on the inner peripheral wall surface of the cylindrical hole 24 of the center housing 6, and extend along the ends of the floating bearing 25. is inserted. Each of these snap springs 40 is arranged at a slight distance from the end face of the floating bearing 25, and these snap springs 40 prevent the floating bearing 25 from moving in the axial direction. Further, as can be seen from FIG. 2, the lubricating oil supply hole 38 opens at the center of the floating bearing 25. As shown in FIGS. 2 to 4, the floating bearing 25 has a substantially hollow cylindrical shape, and an annular outer circumferential groove 42 is formed in the center of the cylindrical outer circumferential wall surface 41 and extends over the entire circumference of the outer circumferential wall surface 41.
is formed. As can be seen from FIG. 2, this annular outer circumferential groove 42 has a width larger than the inner diameter of the opening of the lubricating oil supply hole 38. On the other hand, an annular inner circumferential groove 44 extending over the entire circumference of the inner circumferential wall surface 43 is also formed in the center of the cylindrical inner circumferential wall surface 43 of the floating bearing 25, and this annular inner circumferential groove 44 is connected to the annular outer circumferential groove 42. They have approximately the same width. Furthermore, a plurality of lubricating oil flow holes 47 are formed in the floating bearing 25 to connect the bottom wall 45 of the annular outer circumferential groove 42 and the bottom wall 46 of the annular inner circumferential groove 44 .

When the rotating shaft 11 rotates and lubricating oil is supplied from the lubricating oil supply hole 38, a part of the supplied lubricating oil passes through the gap between the floating bearing outer circumferential wall surface 41 and the center housing cylindrical hole 24 and is supplied to the floating bearing. leaks outside of 25. On the other hand, the remaining lubricating oil is sent into the gap between the floating bearing inner peripheral wall surface 43 and the rotating shaft 11 through the lubricating oil outflow hole 47, and then flows out to the outside of the floating bearing 25. When the rotating shaft 11 rotates, the floating bearing 25 rotates in the same direction as the rotating direction of the rotating shaft 11, even at a lower rotation speed than the rotating shaft 11, and at this time, the floating bearing outer peripheral wall surface 41 and the cylindrical hole 24
The gap therebetween is approximately equal to the gap between the floating bearing inner circumferential wall surface 43 and the rotating shaft 11.

According to the present invention, by forming the outer circumferential groove 42 in the center of the outer circumferential wall surface 41 of the floating bearing 25, the lubricating oil supplied from the lubricating oil supply hole 38 is immediately transferred between the bearing outer circumferential wall surface 41 and the cylindrical hole 24. It is fed into the entire gap. Further, since the length of the lubricating oil distribution hole 47 is short, the lubricating oil supplied into the outer circumferential groove 42 is immediately sent into the inner circumferential groove 44 and then throughout the gap between the bearing inner circumferential wall surface 43 and the rotating shaft 11. will be sent immediately. Therefore, floating bearing 2
5, the lubrication performance is greatly improved, and as a result, the durability of the bearing can be improved. Further, since the outer circumferential groove 42 and the inner circumferential groove 44 are formed, even if there is a burr on the opening periphery of the lubricating oil circulation hole 47, this burr will be removed from the inner circumferential surface of the cylindrical hole 24 or the rotating shaft 11.
have no contact with. Therefore, the lubricating oil flow hole 47
There is no need to chamfer the opening periphery of the floating bearing 25, so manufacturing of the floating bearing 25 becomes extremely easy.
Furthermore, since the width of the outer circumferential groove 42 is larger than the inner diameter of the opening of the lubricating oil supply hole 38, the width of the outer circumferential groove 42 is larger than the inner diameter of the opening of the lubricating oil supply hole 38.
There is no contact with 5. Therefore, the floating bearing 2 is
Since the bearing 5 is not damaged, the life of the bearing can be greatly extended. Furthermore, compared to conventional floating bearings, the cylindrical hole 24 and rotating shaft 11 are
Since the sliding area of the floating bearing 25 is reduced, the viscous friction loss is reduced, and by providing the outer circumferential groove 42 and the inner circumferential groove 44, the rotational inertia of the floating bearing 25 is reduced, so that the turbocharger Responsiveness to rotational speed changes can be improved.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of the turbocharger according to the present invention, FIG. 2 is a partially enlarged side sectional view of the arrow A in FIG. 1, FIG. 3 is a axial sectional view of the floating bearing, and FIG. 3 is a cross-sectional view taken along the line - in FIG. 3. FIG. 11... Rotating shaft, 24... Cylindrical hole for bearing support, 25
... Floating radial bearing, 38... Lubricating oil supply hole, 42... Annular outer circumferential groove, 44... Annular inner circumferential groove, 4
7...Lubricating oil flow hole.

Claims (1)

[Claims] 1. The rotating shaft of the turbocharger is supported by a pair of hollow cylindrical floating radial bearings that are inserted at a distance from each other into the cylindrical hole for bearing support of the turbocharger housing, and a rotary shaft is mounted on the outer peripheral surface of each floating radial bearing. In a turbocharger bearing structure in which a pair of opening lubricating oil supply holes are formed in the turbocharger housing, a width larger than the inner diameter of the opening of the lubricating oil supply hole is provided at the center of the outer peripheral wall of each floating radial bearing. an annular outer circumferential groove extending over the entire circumference of the outer circumferential wall of each floating radial bearing; A bearing structure for a turbocharger in which a groove is formed in each floating radial bearing, and a lubricating oil flow hole is formed in each floating radial bearing to connect the bottom of the annular outer circumferential groove and the bottom of the annular inner circumferential groove to each other.