JP2014152608A - Bearing structure of turbocharger and turbocharger including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing structure of a turbocharger capable of suppressing increase of a peripheral velocity of a contact part of a shaft and a bearing even when the contact part wears out, and a turbocharger including the same.SOLUTION: A first engagement portion (front-side first engagement portion 80a and rear-side first engagement portion 80b) formed into a recessed shape toward the axial direction, is formed on an axial end portion of a shaft 80 supported by a bearing. A sliding portion with the shaft 80, of the bearing is provided with a second engagement portion (second engagement portion 183a and second engagement portion 203a) formed into a projecting shape toward the axial direction of the shaft 80, and engageable with the first engagement portion. The projecting shape has a shape of a rotary body on a rotation axis C approximately in parallel with the axial direction of the shaft 80, and a bus line of the projecting shape is formed so that a distance L1 between the bus line and the rotation axis C is shorter than a distance L2 between a straight line connecting from an apex Pt of the projecting shape to point Pb on an outer peripheral face of a basic end portion of the projecting shape, and the rotation axis C.

Description

  The present invention relates to a bearing structure of a turbocharger provided in an internal combustion engine and a technology of a turbocharger including the same.

  2. Description of the Related Art Conventionally, a turbocharger bearing structure provided in an internal combustion engine and a technology of a turbocharger including the same are well known. For example, as described in Patent Document 1.

  In the turbocharger (supercharger) described in Patent Document 1, a middle portion of a shaft (rotor shaft) is rotatably supported via a bearing (bearing) disposed in a bearing housing (bearing housing). . A compressor housing is disposed on one side of the bearing housing, and a compressor (compressor impeller) connected to one end of the shaft by the compressor housing is included. A turbine housing is disposed on the other side of the bearing housing, and a turbine (turbine impeller) connected to the other end of the shaft by the turbine housing is included.

  In such a turbocharger, in order to reduce the friction between the shaft and the bearing, the diameter of the shaft is reduced, and the peripheral speed (relative speed) at the portion where the shaft and the bearing are in contact is reduced. Conceivable. However, according to this method, the strength of the shaft is reduced, so there is a limit to the reduction in the peripheral speed.

  Therefore, a turbocharger bearing structure as shown in FIG. 8 is conceivable.

  In this bearing structure, a concave (substantially conical) engaging portion 880 a is formed at the end (end surface) of the shaft 880. A bearing 980 having a convex (substantially conical) engaging portion 983a engageable with the concave engaging portion 880a is provided in a compressor housing (or turbine housing) of a turbocharger (not shown). Be placed. By engaging the engaging portion 983a of the bearing 980 with the engaging portion 880a of the shaft 880, the shaft 880 is rotatably supported by the bearing 980.

  In such a bearing structure, the portions where the shaft 880 and the bearing 980 are in contact (the engaging portion 880a and the engaging portion 983a) are located in the vicinity of the axis (rotation center) of the shaft 880. It is possible to reduce the peripheral speed of the portion without reducing.

  However, even in such a bearing structure, when the engaging portion 983a is worn, the peripheral speed of the portion where the shaft 880 and the bearing 980 come into contact with each other increases. This will be specifically described below.

  As shown in FIG. 8B, it is assumed that the shaft 880 and the bearing 980 are initially in contact with each other at the portion Y1 in the vicinity of the distal end portion of the engaging portion 983a. Since the distance Q1 of the portion Y1 from the axis (rotation center) of the shaft 880 is small, the peripheral speed in the portion Y1 is low.

  However, when the engaging portion 983a is worn, the shaft 880 and the bearing 980 come into contact with each other at the base end portion (front side) portion Y2 of the portion Y1 of the engaging portion 983a. Since the distance Q2 of the portion Y2 from the axis (rotation center) of the shaft 880 is larger than the distance Q1 of the portion Y1, the peripheral speed in the portion Y2 is higher than the peripheral speed in the portion Y1. As a result, the friction between the shaft 880 and the bearing 980 increases, and wear of the contacting portion is promoted.

JP 2011-220167 A

  The present invention has been made in view of the situation as described above, and the problem to be solved is that even when the contact portion between the shaft and the bearing is worn, it is possible to suppress an increase in peripheral speed at the portion. Therefore, it is an object to provide a turbocharger bearing structure capable of suppressing an increase in friction of the part and a turbocharger including the same.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, according to the first aspect of the present invention, there is provided a turbocharger bearing structure that rotatably supports a shaft connecting the compressor and the turbine, wherein at least an inner diameter portion of an intake port of the compressor housing or an inner diameter portion of an exhaust port of the turbine housing. A bearing fixed to one side and rotatably supporting the axial end of the shaft is provided, and the axial end of the shaft supported by the bearing has a concave or convex shape in the axial direction. A first engaging portion formed in a shape is formed, and a sliding portion of the bearing with the shaft is formed in a convex shape or a concave shape in the axial direction of the shaft, and the first engagement portion is formed. A second engaging portion that can be engaged with the joint portion is formed, and the convex shape is a rotating body shape about a rotating shaft that is substantially parallel to the axial direction of the shaft, and includes a section that includes the rotating shaft The distance between the generatrix and the rotation axis is a distance between the rotation axis and a straight line that connects the vertex of the convex shape to a point on the outer peripheral surface of the base end of the convex shape. Is formed to be shorter.

  According to a second aspect, the turbocharger bearing structure according to the first aspect is provided.

  As effects of the present invention, the following effects can be obtained.

  In Claim 1, even if the contact part of a shaft and a bearing wears, the increase in the peripheral speed in the said part can be suppressed, and the increase in the friction of the said part can be suppressed by extension.

  In Claim 2, even if the contact part of a shaft and a bearing wears, the increase in the peripheral speed in the said part can be suppressed, and the increase in the friction of the said part can also be suppressed by extension.

The schematic diagram which showed the outline | summary of operation | movement of the turbocharger which concerns on one Embodiment of this invention. Side surface sectional drawing which showed the structure of the turbocharger. (A) The front view which showed the compressor side journal thrust bearing. (B) Similarly, a side sectional view. (A) Side surface sectional drawing which showed the turbine side journal thrust bearing. (B) Similarly, a front view. The side surface sectional enlarged view which showed the shape of the 2nd engaging part and the front side 1st engaging part. The side surface sectional enlarged view which showed the mode of engagement with a 2nd engaging part and a front side 1st engaging part. (A) The front view which showed the compressor side journal thrust bearing which made the 2nd engaging part the concave shape. (B) Similarly, a side sectional view. (A) Side surface sectional drawing which showed the shaft and bearing which have a subject. (B) Similarly, the side cross-sectional enlarged view showing the change of the contact portion due to wear.

  In the following description, the front-rear direction, the up-down direction, and the left-right direction are defined according to the arrows shown in the drawing.

  First, the outline of the operation of the turbocharger 10 according to an embodiment of the present invention will be described with reference to FIG.

  The turbocharger 10 sends compressed air into the cylinder 2 of the engine. Air is supplied to the cylinder 2 through the intake passage 1. The air passes through an air cleaner 4, a turbocharger 10, an intercooler 5, and a throttle valve 6 arranged in the middle of the intake passage 1 in order, and is supplied to the cylinder 2. At this time, since the air is compressed by the compressor 100 of the turbocharger 10, more air can be fed into the cylinder 2.

  Hot air (exhaust gas) after combustion in the cylinder 2 is exhausted through the exhaust passage 3. At this time, the exhaust gas rotates the turbine 120 of the turbocharger 10, and this rotation is transmitted to the compressor 100, whereby the air in the intake passage 1 can be compressed.

  Further, on the upstream side of the turbine 120, the exhaust passage 3 is divided and a passage that does not pass through the turbine 120 is formed separately. The passage can be opened and closed by a waste gate valve 7. The waste gate valve 7 is driven to open and close by an actuator 8. Further, the operation of the actuator 8 is controlled by a negative pressure generating mechanism 9 composed of an electromagnetic valve or the like. By opening and closing the waste gate valve 7 by the actuator 8, the flow rate of the exhaust gas sent to the turbine 120 can be adjusted.

  Next, the configuration of the turbocharger 10 will be described with reference to FIGS.

  The turbocharger 10 mainly includes a compressor housing 20, a turbine housing 40, a center plate 60, a heat shield member 70, a shaft 80, a compressor 100, a turbine 120, a compressor side journal thrust bearing 180, and a turbine side journal thrust bearing 200.

  The compressor housing 20 shown in FIG. 2 forms a part of the intake passage 1 (see FIG. 1) and contains the compressor 100. The compressor housing 20 mainly includes a first compressor housing 21 and a second compressor housing 22.

  The first compressor housing 21 constitutes a front portion of the compressor housing 20. The first compressor housing 21 is formed in a substantially box shape with the rear opened. An intake port 21 a is formed in the first compressor housing 21.

  The intake port 21 a is a through hole that communicates the inside and the outside of the first compressor housing 21. The intake port 21 a is formed on the front side surface of the first compressor housing 21. The intake port 21a is formed such that its axis is directed in the front-rear direction. The air inlet 21a is formed so as to be substantially circular when viewed in cross section (viewed from the front-rear direction).

  The second compressor housing 22 constitutes the rear part of the compressor housing 20. The second compressor housing 22 is formed in a substantially plate shape. The second compressor housing 22 is appropriately fixed to the rear portion of the first compressor housing 21 so as to close the opened rear portion of the first compressor housing 21.

  The turbine housing 40 forms part of the exhaust passage 3 (see FIG. 1) and contains the turbine 120. The turbine housing 40 is formed in a substantially box shape. The turbine housing 40 is disposed behind the compressor housing 20, and is appropriately fixed to the compressor housing 20 (more specifically, the second compressor housing 22) (by fastening bands, bolts, diffusion bonding, friction bonding, or the like). An exhaust port 40 a is formed in the turbine housing 40.

  The exhaust port 40 a is a through hole that communicates the inside and the outside of the turbine housing 40. The exhaust port 40 a is formed on the rear side surface of the turbine housing 40. The exhaust port 40a is formed such that its axis is directed in the front-rear direction. The exhaust port 40 a is formed on the same axis as the intake port 21 a of the compressor housing 20. The exhaust port 40a is formed so as to be substantially circular when viewed in cross section (viewed in the front-rear direction).

  The center plate 60 isolates the internal space of the compressor housing 20 from the internal space of the turbine housing 40. The center plate 60 is disposed at the opened front portion of the turbine housing 40 and closes the opening. A through hole 60 a is formed in the center plate 60.

  The through hole 60a communicates the center plate 60 in the front-rear direction. The through hole 60a is formed such that its axis is directed in the front-rear direction. The through hole 60 a is formed on the same axis as the intake port 21 a of the compressor housing 20 and the exhaust port 40 a of the turbine housing 40. The through-hole 60a is formed so as to be substantially circular when viewed in cross section (viewed from the front-rear direction).

  The heat shield member 70 is for suppressing heat transfer between the compressor housing 20 and the turbine housing 40. The heat shield member 70 is formed of a metal material having high heat resistance. The heat shield member 70 is formed by appropriately processing (bending or the like) a plate-like member in accordance with the shape of the compressor housing 20 and the turbine housing 40. The heat shield member 70 is disposed between the compressor housing 20 and the turbine housing 40 with the plate surface thereof directed in the front-rear direction, and is fixed so as to be sandwiched between the compressor housing 20 and the turbine housing 40. . The heat shield member 70 is formed with a through hole 70a and a cooling passage 70b.

  The through-hole 70a communicates the heat shield member 70 in the front-rear direction. The through-hole 70a is formed so that its axis is directed in the front-rear direction. The through hole 70 a is formed on the same axis as the intake port 21 a of the compressor housing 20 and the exhaust port 40 a of the turbine housing 40. The through hole 70a is formed so as to have a substantially circular shape when viewed in cross section (viewed from the front-rear direction).

  The cooling passage 70b is for cooling the heat shield member 70 by circulating cooling water. The cooling passage 70 b is formed inside the heat shield member 70. Both end portions (not shown) of the cooling passage 70b are communicated with the outer peripheral surface of the heat shield member 70, and cooling water is supplied and discharged through the portion.

  In addition, although the path | route of the cooling passage 70b in the thermal insulation member 70 is determined suitably, it is desirable to form over the said thermal insulation member 70 so that the thermal insulation member 70 can be cooled uniformly.

  The shaft 80 shown in FIGS. 2 to 4 connects the compressor 100 and the turbine 120. The shaft 80 is formed in a substantially cylindrical shape, and is arranged with its longitudinal direction facing the front-rear direction. The shaft 80 is inserted into the through hole 60 a of the center plate 60 and the through hole 70 a of the heat shield member 70. A seal ring (not shown) is provided at a portion inserted through the through hole 60 a of the shaft 80. One end (front end) of the shaft 80 extends into the compressor housing 20. The other end (rear end) of the shaft 80 extends into the turbine housing 40. The shaft 80 is formed with a front first engagement portion 80a and a rear first engagement portion 80b.

  The front first engaging portion 80 a shown in FIG. 3 is a concave portion (concave portion) formed on the front end surface of the shaft 80. The shape of the front first engagement portion 80a will be described in detail later.

  The rear first engaging portion 80b shown in FIG. 4 is a concave portion (concave portion) formed on the rear end surface of the shaft 80. The shape of the rear first engaging portion 80b is formed to be the same as the shape of the front first engaging portion 80a.

  The compressor 100 is an impeller for compressing air. The compressor 100 is disposed in the compressor housing 20 so as to face the intake port 21a. The compressor 100 is fixed to one end (front end) of the shaft 80.

  The turbine 120 is an impeller for converting the motion of air (fluid) into its own rotational motion. The turbine 120 is disposed in the turbine housing 40 so as to face the exhaust port 40a. The turbine 120 is formed integrally with the other end (rear end) of the shaft 80.

  The compressor-side journal thrust bearing 180 shown in FIGS. 2 and 3 supports the shaft 80 so that it can rotate smoothly. The compressor-side journal thrust bearing 180 mainly includes an outer peripheral portion 181, a rib 182, and a sliding portion 183.

  The outer peripheral part 181 is a part formed in an annular shape when viewed from the front. The diameter of the outer peripheral surface of the outer peripheral portion 181 is formed to be substantially the same as the inner diameter of the intake port 21 a of the compressor housing 20.

  The rib 182 shown in FIG. 3 is a portion extending from the inner peripheral surface of the outer peripheral portion 181 toward the central portion of the outer peripheral portion 181. The ribs 182 extend from a plurality of locations (three locations in the present embodiment) on the inner peripheral surface of the rib 182 toward the center of the outer peripheral portion 181.

  The sliding part 183 is a part formed at the center of the outer peripheral part 181. The sliding portion is supported by the rib 182. A second engaging portion 183 a is formed on the sliding portion 183.

  The second engaging portion 183 a is a convex portion (convex portion) formed on the rear side surface of the sliding portion 183. The shape of the second engagement portion 183a will be described in detail later.

  As shown in FIGS. 2 and 3, the compressor-side journal thrust bearing 180 configured as described above is disposed in front of the shaft 80 in the air inlet 21 a of the compressor housing 20. The second engagement portion 183a of the compressor side journal thrust bearing 180 is engaged with the front first engagement portion 80a by being inserted into the front first engagement portion 80a of the shaft 80. In this state, the compressor-side journal thrust bearing 180 is appropriately fixed to the inner diameter portion of the intake port 21a of the compressor housing 20.

  The turbine-side journal thrust bearing 200 shown in FIGS. 2 and 4 supports the shaft 80 so that it can rotate smoothly. The turbine-side journal thrust bearing 200 mainly includes an outer peripheral portion 201, a rib 202, and a sliding portion 203.

  The turbine side journal thrust bearing 200 is formed to have the same shape as the compressor side journal thrust bearing 180. That is, the outer peripheral portion 201, the rib 202, and the sliding portion 203 (second engaging portion 203a) of the turbine side journal thrust bearing 200 are the outer peripheral portion 181 of the compressor side journal thrust bearing 180, the rib 182, and the sliding portion 183 (first step). The two engaging portions 183a) are formed so as to have the same shape.

  The turbine-side journal thrust bearing 200 configured as described above is disposed behind the shaft 80 in the exhaust port 40 a of the turbine housing 40. The second engagement portion 203a of the turbine-side journal thrust bearing 200 is engaged with the rear first engagement portion 80b by being inserted into the rear first engagement portion 80b of the shaft 80. The turbine-side journal thrust bearing 200 is appropriately fixed to the inner diameter portion of the exhaust port 40a of the turbine housing 40 in this state.

  In the turbocharger 10 configured as described above, the turbine 120 is rotated by the exhaust from the cylinder 2 of the engine, and the exhaust is discharged through the exhaust port 40 a of the turbine housing 40. The rotation of the turbine 120 is transmitted to the compressor 100 via the shaft 80. By rotating the compressor 100, the air supplied from the intake port 21a of the compressor housing 20 can be compressed, and the compressed air can be sent to the cylinder 2 of the engine.

  In the turbocharger 10, a load applied in the axial direction of the shaft 80 (direction parallel to the axis) is supported by the compressor-side journal thrust bearing 180 and the turbine-side journal thrust bearing 200. More specifically, the load applied to the shaft 80 from the front to the rear is supported by the turbine-side journal thrust bearing 200, and the load applied to the shaft 80 from the rear to the front is supported by the compressor-side journal thrust bearing 180, respectively. .

  A load applied in the radial direction (direction perpendicular to the axis) of the shaft 80 is also supported by the compressor-side journal thrust bearing 180 and the turbine-side journal thrust bearing 200. Thus, by supporting the load applied in the radial direction of the shaft 80 at two points (the compressor side journal thrust bearing 180 and the turbine side journal thrust bearing 200), the shaft 80 can be supported stably without being inclined. Can do.

  Further, both end portions (front end portion and rear end portion) of the shaft 80 are supported by the compressor-side journal thrust bearing 180 and the turbine-side journal thrust bearing 200, respectively, so that the shaft 80 can be supported without supporting the middle portion of the shaft 80. Can be stably supported. As a result, the configuration for supporting the middle part of the shaft 80 (that is, the housing (bearing housing) for supporting the middle part of the shaft 80) can be eliminated, and the turbocharger 10 as a whole (in particular, the front and rear). (Direction length) can be reduced in size and weight. Along with this, the cost can be reduced.

  Further, when the housing for supporting the middle portion of the shaft 80 is eliminated and the entire turbocharger 10 is downsized, the compressor housing 20 and the turbine housing 40 are brought close to each other. In this case, the heat of the turbine housing 40 that has become hot due to the exhaust from the cylinder 2 of the engine is transmitted to the compressor housing 20, and the durability of the compressor housing 20 is reduced and seizure occurs at each sliding portion. Various heat damages are likely to occur. However, in the present embodiment, by disposing the heat shield member 70 between the compressor housing 20 and the turbine housing 40, it is possible to suppress heat transfer between the compressor housing 20 and the turbine housing 40. As a result, it is possible to suppress the occurrence of the various heat damages described above.

  Further, with the abolition of the bearing housing, the total length (length in the front-rear direction) of the shaft 80 can be shortened, so that the whirl vibration can be reduced. Furthermore, since supply of lubricating oil to the bearing housing is not required, a design that takes into account the supply and discharge directions of the lubricating oil is not required, and the degree of freedom in mounting (position and direction) of the turbocharger 10 is increased.

  The shaft 80 is supported by the compressor-side journal thrust bearing 180 and the turbine-side journal thrust bearing 200 so as to be smoothly rotatable.

  The compressor-side journal thrust bearing 180 supports the shaft 80 by engaging the second engaging portion 183 a with the front first engaging portion 80 a of the shaft 80. Here, the compressor-side journal thrust bearing 180 is slidably in contact with the inner peripheral surface of the front first engaging portion 80a of the shaft 80 on the axis of the shaft 80 (or a point close to the axis).

  Thus, the rotation radius (distance from the axis of the shaft 80) of the portion where the shaft 80 and the compressor-side journal thrust bearing 180 are in contact is 0 (or a value close to 0). For this reason, the peripheral speed (relative speed) at the portion where the shaft 80 and the compressor-side journal thrust bearing 180 are in contact with each other is 0 at the apex of the second engagement portion 183a (other portions of the second engagement portion 183a). (Small value close to 0 in the portion). Therefore, it is possible to suppress friction at a portion where the shaft 80 and the compressor-side journal thrust bearing 180 are in contact with each other. As a result, the wear resistance and seizure resistance of the part can be improved, and at the same time, the transient performance and the turbo efficiency can be improved by reducing the friction torque loss.

  Similarly, the turbine-side journal thrust bearing 200 is slidably in contact with the inner peripheral surface of the rear first engaging portion 80b of the shaft 80 on the axis of the shaft 80 (or a point close to the axis). Become. Accordingly, it is possible to suppress friction at a portion where the shaft 80 and the turbine-side journal thrust bearing 200 are in contact with each other. As a result, the wear resistance and seizure resistance of the part can be improved, and at the same time, the transient performance and the turbo efficiency can be improved by reducing the friction torque loss.

  In the case of a configuration that supports the middle portion of the shaft 80 using a bearing housing (configuration as in the prior art), the peripheral speed of the support portion may be lowered by reducing the diameter of the shaft 80. Is possible. However, according to this method, the strength of the shaft 80 is reduced, so there is a limit to the reduction in peripheral speed. Compared to this, in the bearing structure according to the present embodiment, since it is not necessary to reduce the diameter of the shaft 80, it is possible to reduce the circumferential speed while maintaining the strength of the shaft 80.

  Further, as described above, the friction (wear) of the sliding portion 183 of the compressor side journal thrust bearing 180 and the sliding portion 203 of the turbine side journal thrust bearing 200 can be suppressed. The need to lubricate and cool 203 is reduced. As a result, it is possible to omit lubrication with lubricating oil (or lubrication with simple grease or the like).

  Further, since the supply amount of the lubricating oil to the support portion of the shaft 80 (the compressor-side journal thrust bearing 180 and the turbine-side journal thrust bearing 200) can be reduced as a whole, the stirring resistance of the lubricating oil can be reduced. As a result, mechanical loss can be reduced and turbo efficiency can be improved.

  Further, since the compressor side journal thrust bearing 180 is disposed in the intake port 21a of the compressor housing 20, it is cooled by the air supplied to the turbocharger 10 through the intake port 21a. Accordingly, it is not necessary to separately provide a mechanism for cooling the sliding portion 183 of the compressor side journal thrust bearing 180 (even if it is provided, a large cooling capacity is not necessary, so the configuration can be simplified).

  Since the turbine housing 40 is heated by exhaust from the cylinder 2 of the engine, a mechanism for cooling and lubricating the turbine side journal thrust bearing 200 may be separately provided.

Below, the shape of the 2nd engaging part 183a of the compressor side journal thrust bearing 180 and the front 1st engaging part 80a of the shaft 80 is demonstrated in detail.
Since the second engagement portion 203a of the turbine side journal thrust bearing 200 and the rear first engagement portion 80b of the shaft 80 have the same shape, the description thereof is omitted.

  As shown in FIG. 5, the convex shape of the second engaging portion 183a and the concave shape of the front first engaging portion 80a are formed so as to have a rotating body shape about a predetermined rotation axis C. FIG. 5 shows a cross section including the rotation axis C.

  Here, the rotation axis C is an axis substantially parallel to the axial direction of the shaft 80 (the front-rear direction in the present embodiment).

  In the present embodiment, the rotational axis C of the convex shape of the second engaging portion 183a and the concave shape of the front first engaging portion 80a is assumed to be coincident with (overlapping with) the axis of the shaft 80. Since the shaft 80 may be slightly inclined with respect to the compressor-side journal thrust bearing 180, the axis of the shaft 80 and the rotation axis C of the compressor-side journal thrust bearing 180 may not completely coincide.

  Let the convex vertex of the second engagement portion 183a be Pt, and the point on the outer peripheral surface of the convex proximal end portion (the rightmost end portion in FIG. 5) be Pb.

  The convex shape of the second engagement portion 183a is formed to be a curved shape from the point Pb to the vertex Pt in a cross-sectional view. The convex shape of the second engagement portion 183a is such that the distance L1 between an arbitrary point Pc on the rotation axis C and its generatrix (a line indicating the outer peripheral surface of the second engagement portion 183a in FIG. 5) is It is formed to be shorter than the distance L2 from the straight line connecting the vertex Pt to the point Pb. In this way, the convex shape of the second engagement portion 183a is formed in a curved shape that is recessed inside the rotation axis C in a cross-sectional view.

  The concave shape of the front first engaging portion 80a is formed in a shape that follows the convex shape of the second engaging portion 183a. More specifically, the concave shape of the front first engagement portion 80a is formed to be slightly wider outward than the second engagement portion 183a.

  As shown in FIG. 6, when the second engaging portion 183 a configured as described above and the front first engaging portion 80 a are engaged, the second engaging portion 183 a is a front end portion of the convex shape. It contacts the bottom of the concave shape of the first engaging portion 80a.

  Here, in a side sectional view, the convex tip portion of the second engagement portion 183a is formed in an arc shape having a radius r1, and the concave bottom portion of the front side first engagement portion 80a is formed in an arc shape having a radius r2. Is done. The radius r1 of the second engagement portion 183a is formed to be smaller than the radius r2 of the front first engagement portion 80a. By comprising in this way, it can prevent that the 2nd engaging part 183a is completely fitted by the front side 1st engaging part 80a, and the rotation of the shaft 80 is inhibited.

  When the distal end portion of the second engagement portion 183a is worn due to the rotation of the shaft, the second engagement portion 183a is engaged with the front side first engagement at a portion X1 slightly proximal to the front end portion (front side). It comes into contact with the portion 80a. A distance of the portion X1 from the axis line (rotation axis C) of the shaft 80 is R1.

  For convenience of explanation, the second engaging portion 183a is assumed to be in contact with the front first engaging portion 80a at one point (part X1) on the outer peripheral surface. However, in practice, the second engaging part 183a has a certain range including the part X1. The surface (curved surface) is in contact with the front first engagement portion 80a.

  When the shaft 80 further rotates and the vicinity of the distal end of the second engagement portion 183a (the portion including the portion X1) wears, the second engagement portion 183a gradually becomes slightly proximal (side forward) from the portion X1. ) Portion X2 comes into contact with the front first engaging portion 80a. The distance of the portion X2 from the axis line (rotation axis C) of the shaft 80 is R2.

  Here, since the convex shape of the second engagement portion 183a is formed in a curved shape that is recessed inside the rotation axis C in a cross-sectional view, the contact portion with the front first engagement portion 80a is changed from the portion X1 to the portion X2. Even if it moves to (to the base end side), the distance (distance R2−distance R1) from the axis (rotation axis C) of the shaft 80 of the contact portion does not increase so much.

  That is, even if the second engagement portion 183a is worn, the distance (rotation radius) from the axis of the shaft 80 of the portion where the second engagement portion 183a and the front first engagement portion 80a are in contact does not increase so much. The peripheral speed at the contact portion does not increase so much. Therefore, an increase in friction at the contact portion can be suppressed, and as a result, progress of wear and occurrence of damage at the contact portion can be suppressed.

  As described above, the bearing structure of the turbocharger 10 according to the present embodiment is a bearing structure of the turbocharger 10 that rotatably supports the shaft 80 that connects the compressor 100 and the turbine 120, and the intake port of the compressor housing 20. Bearings that are fixed to the inner diameter portion of 21a and the inner diameter portion of the exhaust port 40a of the turbine housing 40 and that rotatably support the axial end portion of the shaft 80 (compressor side journal thrust bearing 180 and turbine side journal thrust bearing 200) And a first engagement portion (a front first engagement portion 80a and a rear first engagement) formed in a concave shape in the axial direction at an axial end portion of the shaft 80 supported by the bearing. A joint portion 80b) is formed, and the sliding portion of the bearing with the shaft 80 faces the axial direction of the shaft 80. And a second engagement portion (second engagement portion 183a and second engagement portion 203a) that can be engaged with the first engagement portion is formed. It is a rotating body shape about a rotation axis C substantially parallel to the axial direction of 80, and the convex bus in the sectional view including the rotation axis C has a distance L1 between the bus and the rotation axis C of the convex shape. It is formed so as to be shorter than the distance L2 between the rotation axis C and a straight line connecting the vertex Pt to the point Pb on the outer peripheral surface of the convex base end portion.

  Further, the turbocharger 10 according to the present embodiment is characterized by including the above-described bearing structure of the turbocharger 10.

  By comprising in this way, even if the contact part of the shaft 80 and a bearing wears, the increase in the peripheral speed in the said part can be suppressed, and by extension, the increase in the friction of the said part can be suppressed. As a result, it is possible to suppress the progress of wear and the occurrence of damage of the portion.

As shown in FIG. 7, the front first engaging portion 80 a of the shaft 80 has a convex shape, and the second engaging portion 183 a formed on the sliding portion 183 of the compressor-side journal thrust bearing 180 has a concave shape. Each can also be formed.
Thus, as long as one of the front side first engaging portion 80a and the second engaging portion 183a has a convex shape and the other has a concave shape, either one may have a convex shape (concave shape).

  Similarly, the rear first engaging portion 80b of the shaft 80 is formed in a convex shape, and the second engaging portion 203a formed in the sliding portion 203 of the turbine side journal thrust bearing 200 is formed in a concave shape. It is also possible to do.

  In this embodiment, both ends of the shaft 80 are rotatably supported by bearings (compressor-side journal thrust bearing 180 and turbine-side journal thrust bearing 200). However, the present invention is not limited to this. Alternatively, either the compressor-side journal thrust bearing 180 or the turbine-side journal thrust bearing 200 may be eliminated, and instead, the middle portion of the shaft 80 may be rotatably supported by another bearing.

DESCRIPTION OF SYMBOLS 10 Turbocharger 20 Compressor housing 21a Intake port 40 Turbine housing 40a Exhaust port 80 Shaft 80a Front side 1st engaging part (1st engaging part)
80b Rear first engaging portion (first engaging portion)
100 Compressor 120 Turbine 180 Compressor-side journal thrust bearing (bearing)
183a Second engaging portion 200 Turbine side journal thrust bearing (bearing)
203a Second engaging portion

Claims (2)

A turbocharger bearing structure that rotatably supports a shaft connecting a compressor and a turbine,
A bearing that is fixed to at least one of the inner diameter portion of the intake port of the compressor housing or the inner diameter portion of the exhaust port of the turbine housing and rotatably supports the axial end portion of the shaft;
A first engagement portion formed in a concave shape or a convex shape in the axial direction is formed at an axial end portion of the shaft supported by the bearing,
A sliding portion of the bearing with the shaft is formed in a convex shape or a concave shape in the axial direction of the shaft, and a second engaging portion that can be engaged with the first engaging portion is formed. And
The convex shape is
It is a rotating body shape about a rotation axis substantially parallel to the axial direction of the shaft,
The convex generatrix in cross-sectional view including the rotation axis is
The distance between the generatrix and the rotation axis is formed to be shorter than the distance between the rotation axis and a straight line connecting the vertex of the convex shape to a point on the outer peripheral surface of the base end portion of the convex shape. It is characterized by
Turbocharger bearing structure. The turbocharger bearing structure according to claim 1 is provided.
Turbocharger.

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