JP2016114221A - Bearing for supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing for a supercharger which is easy to manufacture, and can suppress a foreign substance in a lubrication oil circulating in a guide groove formed on an inner peripheral surface of the bearing from entering between a turbine shaft and the bearing.SOLUTION: A bearing 20 for a supercharger has a cylindrical shape in which a through-hole through which a turbine shaft 10 is inserted is formed, and rotatably supports the turbine shaft 10. On an inner peripheral surface 22 on both end parts of the bearing 20, a guide groove 23 is formed which extends in an axial direction and in which a lubrication oil circulates. Then, a protrusion 25 is provided which is, out of corner parts 24f, 24b formed by the inner peripheral surface 22 of the bearing 20 and a wall surface of the guide groove 23, formed on the corner part 24f on the rotation direction front side of the turbine shaft 10, and suppresses a foreign substance f in the lubrication oil circulating in the guide groove 23 from entering a gap between the turbine shaft 10 and the bearing 20. The protrusion 25 is a burr formed by machine processing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a turbocharger bearing that rotatably supports a turbine shaft. In particular, the present invention relates to a turbocharger bearing that can be easily manufactured but can prevent foreign matters in lubricating oil flowing in guide grooves formed on the inner peripheral surface of the bearing from entering between a turbine shaft and the bearing.

  As one of devices for increasing the output of an internal combustion engine (engine), a supercharger (turbocharger) that sends compressed air using an exhaust gas to the internal combustion engine is known (see Patent Document 1). The supercharger includes a turbine shaft that connects the turbine wheel and the compressor wheel, a bearing that rotatably supports the turbine shaft, and a bearing housing that houses the turbine shaft and the bearing. In general, the bearing is accommodated in a bearing hole formed in the bearing housing, and the turbine shaft is rotatably supported with respect to the housing. A floating metal is usually used for a bearing of a supercharger for an automobile, and the floating metal includes a semi-floating metal and a full floating metal.

  Patent Document 1 discloses a supercharger including a guide groove on an inner peripheral surface (slip surface) of a floating metal. The guide groove extends in the axial direction of the floating metal, and the lubricating oil is circulated. Of the wall portions of the floating metal that form the guide grooves, a foreign matter holding portion is formed on the wall portion on the front side in the rotational direction of the turbine shaft. The foreign matter holding part captures foreign matter mixed in the lubricating oil in the guide groove.

JP 2014-51898 A

  In Patent Document 1, a guide groove for promoting the flow of lubricating oil is provided on the inner peripheral surface (slip surface) of the bearing, and foreign matter that has entered the guide groove is prevented from being caught between the turbine shaft and the bearing. In order to do so, it has been proposed to provide a foreign matter holding part. Specifically, with respect to the shape of the guide groove in which the foreign matter holding part is formed, the tangent of the portion that is continuous with the wall portion on the front side in the rotational direction of the turbine shaft on the sliding surface and the rotational direction of the turbine shaft that forms the foreign matter holding part Among the angles formed by the front wall portion, the angle on the front side in the rotational direction of the turbine shaft from the wall portion is 90 degrees or less.

  However, in order to form a groove having a shape as described in Patent Document 1 on the inner peripheral surface of the bearing by machining, a complicated and precise machining operation is required. Also gets higher. In particular, since the turbocharger for automobiles is small in size and the bearing is small in size, it is difficult to form a groove having a shape as described in Patent Document 1. Therefore, while easy to manufacture, the guide groove formed on the inner peripheral surface of the bearing can promote the flow of the lubricating oil, and foreign matter in the lubricating oil flowing through the guide groove enters between the turbine shaft and the bearing. Development of a bearing that can suppress this is desired.

  Accordingly, one of the objects of the present invention is to make it possible for foreign matter in the lubricating oil flowing in the guide groove formed on the inner peripheral surface of the bearing to enter between the turbine shaft and the bearing while being easy to manufacture. It is providing the bearing for superchargers which can be suppressed.

  (1) A turbocharger bearing according to an embodiment of the present invention is a turbocharger bearing that is cylindrical and rotatably supports a turbine shaft. The supercharger bearing includes an inner peripheral surface formed such that a guide groove through which lubricating oil flows at at least one end of the bearing extends in a direction intersecting the circumferential direction of the bearing, and the inner peripheral surface of the bearing and the guide Of the corners formed by the wall surface of the groove, formed at the corners on the front side in the rotational direction of the turbine shaft, and foreign matter in the lubricating oil flowing through the guide groove enters the gap between the turbine shaft and the bearing. And a protrusion to be suppressed. The protrusion is a burr formed by machining.

  According to the above turbocharger bearing, by providing an inner peripheral surface (slip surface) formed with a guide groove through which the lubricating oil flows, it is possible to promote the flow of the lubricating oil and lubricate between the turbine shaft and the bearing. Oil is supplied sufficiently. Therefore, the lubricating oil can lubricate between the turbine shaft and the bearing, and the oil film can reduce the friction between the turbine shaft and the bearing. Furthermore, by providing a protrusion that prevents foreign matter in the lubricating oil flowing through the guide groove from entering the gap between the turbine shaft and the bearing, foreign matter can be prevented from entering between the turbine shaft and the bearing. . For this reason, it is possible to reduce the wear of the bearing due to the biting of foreign matter, and to reduce the occurrence of breakage due to wear or the like. In addition, since the protrusion is a burr formed by machining when forming a through hole or guide groove through which the turbine shaft is inserted in the bearing, it can be easily formed simultaneously with machining, and the formation of the protrusion (burr) In addition, complicated and precise machining accuracy is not required, so it can be realized at low cost. In mechanical parts such as bearings, it is normal to remove burrs. However, in the above-described turbocharger bearing, burrs are left, so there is no need to remove burrs, and the number of processing steps can be reduced. Therefore, in the turbocharger bearing, foreign matter in the lubricating oil flowing in the guide groove formed on the inner peripheral surface of the bearing is caused by the protrusions (burrs) formed when machining the turbine shaft and the bearing. In addition to being able to suppress intrusion, the manufacture is easy.

It is a schematic sectional drawing which shows an example of a supercharger. It is a schematic sectional drawing which shows the bearing for superchargers which concerns on embodiment. It is a general | schematic fragmentary enlarged view which shows an example of the bearing for superchargers which concerns on embodiment. It is a schematic partial enlarged view which shows another example of the bearing for superchargers which concerns on embodiment.

  Hereinafter, a specific example of a turbocharger bearing according to an embodiment of the present invention will be described with reference to the drawings. The same reference numerals in the figure indicate the same names. First, the outline of the supercharger will be described with reference to FIG. 1, and then the supercharger bearing according to the embodiment will be described in detail with reference to FIGS. 2 to 4.

[Embodiment]
<Supercharger>
A supercharger T shown in FIG. 1 is an automobile exhaust turbine supercharger (so-called turbocharger) that sends compressed air using engine exhaust gas (not shown) to the engine. The supercharger T includes a turbine shaft 10, a bearing 20, and a bearing housing 30 that houses the turbine shaft 10 and the bearing 20.

(Turbine shaft)
The turbine shaft 10 is connected to the turbine wheel 11 and the compressor wheel 12 at both ends, and connects the turbine wheel 11 and the compressor wheel 12. The turbine wheel 11 is provided in the middle of the exhaust path (for example, downstream of the exhaust manifold (not shown)), and the compressor wheel 12 is provided in the middle of the intake path (for example, upstream of the intake manifold (not shown)). It is done. When the turbine wheel 11 is rotated by the exhaust gas flowing in the exhaust path, the turbine shaft 10 is rotated, and the compressor wheel 12 is rotated via the turbine shaft 10 to compress the air in the intake path and send it to the engine.

(bearing)
The bearing 20 is a cylindrical part in which a through-hole through which the turbine shaft 10 is inserted is formed, and supports the turbine shaft 10 in a rotatable manner. The bearing 20 has an inner diameter at both end portions smaller than an inner diameter at the intermediate portion (see also FIG. 2A) and is substantially equal to the outer diameter of the turbine shaft 10, and the inner peripheral surface at both ends supports the turbine shaft 10. To do. That is, slip surfaces are formed on the inner peripheral surfaces of both ends of the bearing 20. The bearing 20 is accommodated in a bearing hole 31 formed in the bearing housing 30 in a state where the turbine shaft 10 is inserted. In this example, the bearing 20 is a semi-floating metal. A detailed description of the bearing 20 will be described later.

(Bearing housing)
The bearing housing 30 is formed with a bearing hole 31 that accommodates the turbine shaft 10 and the bearing 20, and the turbine shaft 10 is rotatably supported by the bearing hole 31 via the bearing 20. The bearing housing 30 is formed with an oil supply passage 33 that penetrates the bearing hole 31 and supplies lubricating oil to the bearing 20 and an oil discharge passage 35 that discharges the lubricating oil discharged by lubricating the bearing 20. . The bearing 20 is formed with an oil hole 21 penetrating from the outer peripheral surface to the inner peripheral surface at a position facing the outlet opening of the oil supply passage 33 (see also FIG. 2A). The lubricating oil supplied to 20 is supplied between the turbine shaft 10 and the bearing 20 through the oil hole 21. The supplied lubricating oil flows to both end surfaces of the bearing 20, is discharged from the opening, and is discharged to the oil discharge path 35. A turbine housing 40 that houses the turbine wheel 11 and a compressor housing 50 that houses the compressor wheel 12 are connected to both sides of the bearing housing 30.

<Bearing>
Hereinafter, the details of the bearing 20 provided in the supercharger T will be described with reference to FIGS. In FIG. 2, the right figure (A) is a longitudinal sectional view cut through a plane parallel to the axial direction through the central axis of the bearing 20, and the left figure (B) is BB in the right figure (A). 2 is a cross-sectional view taken along a plane passing through a line and perpendicular to the axial direction of the bearing 20. FIG. 3 and 4 are enlarged views of the vicinity of a portion where one guide groove 23 is formed in the cross section of the bearing 20 through which the turbine shaft 10 is inserted. For easy understanding, the cross section is hatched. Omitted.

(Guide groove)
As shown in FIG. 2A, the bearing 20 has an inner peripheral surface (slip surface) formed so that the guide grooves 23 through which the lubricating oil flows extend in the direction intersecting the circumferential direction of the bearing 20 at both ends. Is provided. In this example, as shown in FIG. 2B, four guide grooves 23 extending in the axial direction from the both end surfaces are provided at equal intervals in the circumferential direction on each inner peripheral surface (slip surface) of both ends of the bearing 20. Is formed. Each guide groove 23 is formed in a direction orthogonal to the circumferential direction of the bearing 20 (in other words, a direction parallel to the axial direction of the bearing 20). The cross-sectional shape of each guide groove 23 is a substantially arc shape (more specifically, a substantially semicircular shape). The number and cross-sectional shape of the guide grooves 23 can be changed as appropriate. For example, the cross-sectional shape of the guide groove 23 can be a substantially triangular shape, a substantially rectangular shape, a substantially inverted trapezoidal shape, a substantially elliptic arc shape, or a substantially semi-elliptical shape.

  The lubricating oil supplied between the turbine shaft 10 and the bearing 20 through the oil hole 21 flows through the guide groove 23 (see also FIG. 1). When the turbine shaft 10 rotates, along with the rotation, a flow along the rotation direction is generated around the turbine shaft 10, and the lubricant flows from the guide groove 23 to the inner peripheral surface side of the bearing 20 by the flow in the circumferential direction. Flows out and enters between the turbine shaft 10 and the bearing 20 to form an oil film. The lubricating oil flows through the guide groove 23 to the both end face sides of the bearing 20 and is discharged from the end face opening. Since the guide groove 23 facilitates the flow of the lubricating oil and facilitates the flow of foreign matter in the lubricating oil, the guide groove 23 improves the oil permeability and the dischargeability of the foreign matter. Therefore, the lubricating oil is sufficiently supplied between the turbine shaft 10 and the bearing 20 so that an oil film is easily formed, and the lubricity of the sliding surface is improved. Clogging can be suppressed.

(Projection)
Further, as shown in FIGS. 3 and 4, the bearing 20 has a rotation direction of the turbine shaft 10 among corner portions 24 f and 24 b formed by the inner peripheral surface (slip surface) 22 of the bearing 20 and the wall surface of the guide groove 23. A protrusion 25 is provided on the front corner 24f. The protrusion 25 suppresses the foreign matter f in the lubricating oil flowing through the guide groove 23 from entering the gap between the turbine shaft 10 and the bearing 20. As the protrusion 25, as shown in FIG. 3, the protrusion 25a protruding in the tangential direction of the inner peripheral surface 22 of the bearing 20 from the wall surface of the guide groove 23 in the corner 24f, or the corner 24f as shown in FIG. A protrusion 25b that protrudes from the inner peripheral surface 22 of the bearing 20 in the tangential direction of the wall surface of the guide groove 23 is exemplified.

  Here, a mechanism for suppressing foreign matter intrusion by the protrusion 25 will be described. As described above, when the turbine shaft 10 rotates, the flow in the circumferential direction along the rotation direction of the turbine shaft 10 (indicated by white arrows in FIGS. 3 and 4) (in FIG. 3 and FIG. 4, with thin line arrows). Along with this, a circumferential flow from the rear corner 24b of the turbine shaft 10 toward the front corner 24f occurs along the wall surface. Therefore, if the foreign matter f is mixed in the lubricating oil in the guide groove 23, the foreign matter f moves along the wall surface of the guide groove 23 by the above flow, and the inner periphery of the bearing 20 from the corner 24 f side of the guide groove 23. The foreign substance f tends to flow out together with the lubricating oil to the surface 22 side. In the case of the protrusion 25a shown in FIG. 3 protruding from the corner portion 24f in the tangential direction of the inner peripheral surface 22 of the bearing 20, the protrusion 25a prevents the foreign material f from flowing out of the guide groove 23, and the turbine shaft 10 and the bearing 20 The foreign matter f is prevented from entering during the period. In the case of the protrusion 25b shown in FIG. 4 protruding from the corner portion 24f in the tangential direction of the wall surface of the guide groove 23, the distance from the turbine shaft 10 is narrow at the position where the protrusion 25b is formed on the inner peripheral surface 22 of the bearing 20. The movement of the foreign material f from the guide groove 23 toward the inner peripheral surface 22 is prevented, and the foreign material f is prevented from entering between the turbine shaft 10 and the bearing 20.

  Further, the protrusion 25 is a burr formed by machining. Machining includes cutting and grinding. Hereinafter, a method for forming the protrusion 25 will be described.

  When the protrusion 25a (burr) shown in FIG. 3 protruding in the tangential direction of the inner peripheral surface 22 of the bearing 20 is formed from the corner portion 24f, the guide groove 23 is formed in the bearing 20, and then the inner peripheral surface 22 of the bearing 20 is formed. In addition to machining, the machining direction with respect to the inner peripheral surface 22 is set to a direction opposite to the rotation direction of the turbine shaft 10 (clockwise in FIG. 3). Specific examples include the following forming methods. A guide groove 23 is formed in a cylindrical bearing material in which a through hole is formed. For example, the guide groove 23 may be formed by cutting using a rotary cutting tool such as an end mill. Then, after the guide groove 23 is formed, the inner peripheral surface of the bearing material is cut using a rotary cutting tool such as a drill, an end mill, or a reamer. At that time, by making the rotation direction of the rotary cutting tool opposite to the rotation direction of the turbine shaft 10, the machining direction is opposite to the rotation direction of the turbine shaft 10 with respect to the inner peripheral surface 22. A burr (projection 25a) protruding in the tangential direction of the peripheral surface 22 is formed in the corner portion 24f. In the case of cutting, the inner peripheral surface of the bearing material may be turned using a turning tool such as a cutting tool. In this case, by turning the bearing material in the same direction as the rotation direction of the turbine shaft 10, the machining direction is opposite to the rotation direction of the turbine shaft 10 with respect to the inner peripheral surface 22. Alternatively, the inner peripheral surface of the bearing material may be ground using a grinding tool such as a grindstone or a file. In this case, grinding is performed while rotating or moving the grinding tool in the direction opposite to the rotation direction of the turbine shaft 10, so that the machining direction is opposite to the rotation direction of the turbine shaft 10 with respect to the inner peripheral surface 22. As another forming method, after forming a hole to be the guide groove 23 in the axial direction on both ends of the cylindrical bearing material on the same circumference of the central axis, the guide groove 23 of the hole The through hole is formed by cutting in the direction of the central axis while leaving the portion to be formed. Then, when forming the through hole, the machining direction is opposite to the rotation direction of the turbine shaft 10 with respect to the inner peripheral surface 22 by cutting while rotating the cutting tool in the direction opposite to the rotation direction of the turbine shaft 10. become.

  When forming the protrusion 25b (burr) shown in FIG. 4 protruding from the corner 24f in the tangential direction of the wall surface of the guide groove 23, the guide groove 23 is formed when the guide groove 23 is formed in the cylindrical bearing 20 in which the through hole is formed. The wall surface of the groove 23 is machined, and the machining direction with respect to the wall surface is set to the same direction as the rotation direction of the turbine shaft 10 (counterclockwise in FIG. 4). Specifically, the wall surface of the guide groove 23 is cut using a rotary cutting tool. At that time, by making the rotation direction of the rotary cutting tool the same as the rotation direction of the turbine shaft 10, the machining direction becomes the same as the rotation direction of the turbine shaft 10 with respect to the wall surface, and the tangent to the wall surface of the guide groove 23. A burr (projection 25b) protruding in the direction is formed at the corner 24f. Alternatively, the wall surface of the guide groove 23 is ground using a grinding tool, and at that time, the grinding tool is ground while rotating or moving in the same direction as the rotation direction of the turbine shaft 10, thereby processing the wall surface. The direction is the same as the rotational direction of the turbine shaft 10.

  The supercharger bearing 20 according to the embodiment described above can achieve the following effects.

  By providing the inner peripheral surface (slip surface) formed with the guide groove 23 through which the lubricating oil flows, the guide groove 23 improves oil permeability and foreign matter discharge, so that the gap between the turbine shaft 10 and the bearing 20 is improved. In addition to improving lubricity, it is possible to suppress stagnation and adhesion of foreign matters.

  Further, a protrusion 25 (protrusions 25 a and 25 b) is provided at a corner portion 24 f on the front side in the rotational direction of the turbine shaft 10, and the foreign matter f in the lubricating oil flowing through the guide groove 23 is caused by the turbine shaft 10 and the bearing 20. Therefore, the foreign matter f can be prevented from entering between the turbine shaft 10 and the bearing 20. Therefore, the wear of the bearing 20 due to the biting of the foreign substance f can be reduced, and the occurrence of breakage due to wear or the like can be reduced. Further, since the protrusion 25 is a burr formed by machining the inner peripheral surface 22 of the bearing 20 and the wall surface of the guide groove 23 when the bearing 20 is manufactured, it can be easily formed simultaneously with machining. Can be realized at low cost. In addition, since the protrusions 25 are formed by burrs, there is no need for deburring, and the number of processing steps can be reduced.

  Since the protrusion 25 is a burr formed by machining, the protrusion 25 disappears due to wear while the supercharger is used, and the influence on the function as a bearing is small. In particular, the protrusion 25b shown in FIG. 4 protruding from the corner 24f in the tangential direction of the wall surface of the guide groove 23 is easily worn away. In general, automobiles share the lubricating oil of the engine and the supercharger, and metal wear powder is likely to be generated in the early stage of use of the engine, and metal wear powder is likely to be mixed into the lubricant as foreign matter f. Therefore, in the initial stage of use, there is a high probability that the foreign material f enters between the turbine shaft 10 and the bearing 20, and the foreign material f is likely to be caught. That is, it is effective to suppress the entry of the foreign substance f between the turbine shaft 10 and the bearing 20 in the initial use. Therefore, even if the protrusion 25 is worn away with time due to use, it is highly effective because the protrusion 25 suppresses the entry of the foreign substance f in the initial stage of use.

  In the embodiment described above, the case where the bearing is a semi-floating metal has been described, but the bearing may be a full floating metal.

  The present invention is not limited to these exemplifications, is shown by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  The supercharger bearing of the present invention can be suitably used for a supercharger for automobiles.

T turbocharger 10 turbine shaft 11 turbine wheel 12 compressor wheel 20 bearing 21 oil hole 22 inner peripheral surface (slip surface)
23 guide groove 24f, 24b corner 25, 25a, 25b protrusion (burr)
30 Bearing housing 31 Bearing hole 33 Oil supply path 35 Oil discharge path 40 Turbine housing 50 Compressor housing f Foreign matter

Claims (1)

A turbocharger bearing that is cylindrical and rotatably supports a turbine shaft,
An inner peripheral surface formed such that a guide groove through which lubricating oil flows at at least one end of the bearing extends in a direction intersecting the circumferential direction of the bearing;
Of the corners formed by the inner peripheral surface of the bearing and the wall surface of the guide groove, the foreign matter in the lubricating oil that is formed at the corner on the front side in the rotational direction of the turbine shaft and circulates in the guide groove is the turbine. A protrusion that suppresses entry into the gap between the shaft and the bearing,
The supercharger bearing, wherein the protrusion is a burr formed by machining.

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