JP7143028B2 - Exhaust turbocharger bearing structure - Google Patents

Description

The present invention relates to the structure of a bearing for an exhaust turbocharger attached to an internal combustion engine.

The turbine wheel (or impeller) is rotated using the energy of the exhaust gas discharged from the cylinder of the internal combustion engine, and the rotation is transmitted to the compressor wheel (impeller) to pressurize and compress (supercharge) the intake air. Exhaust turbochargers are well known in which exhaust gas is fed into the cylinders.

A semi-floating bearing is often used to support a shaft connecting a turbine wheel and a compressor wheel in a bearing housing (or center housing). In the semi-floating bearing, a cylindrical bearing metal through which the shaft is inserted is arranged in a bearing hole formed in the housing, and the housing and the bearing are combined to prevent displacement along the axial direction and rotation around the axis of the bearing metal. A pin is pressed through both sides of the metal (see, for example, the following patent document).

However, it is impossible to completely prevent the pin from falling out of the housing and bearing metal.

Although it is not unthinkable to use bolts instead of pins, the accuracy of the mounting position due to screwing is low. As a result, there is concern that the bearing metal and thus the position of the shaft may vary, and the gap between the blades of the turbine wheel or compressor wheel and the housing may widen, degrading efficiency.

WO2017/069025

SUMMARY OF THE INVENTION An intended object of the present invention is to prevent a pin for positioning a bearing metal from coming out of a semi-floating bearing that serves as a bearing for an exhaust turbocharger.

The present invention relates to a structure in which a shaft connecting a turbine wheel and a compressor wheel of an exhaust turbosupercharger is supported in a bearing housing. a bearing portion provided in the bearing housing and including a bearing hole into which the shaft and the bearing metal are inserted and having a through hole formed in the peripheral wall thereof; A pin for restraining axial relative displacement and relative rotation about the axis with respect to the bearing housing is separate from the pin and is screwed from the outside into the through hole into which the pin is inserted to close the through hole. and a bolt, and an oil supply passage communicating with the bearing hole is formed in the bearing housing separately from the through hole .

ADVANTAGE OF THE INVENTION According to this invention, in the semi-floating bearing which becomes a bearing of an exhaust turbocharger, it is possible to appropriately prevent the pin for positioning the bearing metal from coming out.

1 is a cross-sectional view showing the structure of an exhaust turbocharger according to an embodiment of the present invention; FIG. FIG. 2 is an enlarged cross-sectional view of a main part showing the structure of the bearing of the exhaust turbosupercharger of the same embodiment;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the overall structure of the exhaust turbocharger in this embodiment. The exhaust turbocharger of the present embodiment is a water-cooled supercharger in which the housing (or casing) is made of an aluminum alloy.

The housing includes a bearing housing (center housing) 2 , a turbine housing 1 and a compressor housing 3 . In this embodiment, the bearing housing 2 and the compressor housing 3 are separate members, but the bearing housing 2 and the turbine housing 1 are formed integrally.

A bearing portion 21 containing a bearing hole 22 is formed in the bearing housing 2, and a semi-floating bearing is provided in the bearing hole 22 to form a rotating shaft connecting a turbine wheel (impeller) 4 and a compressor wheel (impeller) 5. A shaft 6 is rotatably supported. The turbine wheel 4 is housed in the turbine housing 1 and the compressor wheel 5 in the compressor housing 3, respectively.

An intake port 31 is opened in the compressor housing 3 . Further, by fastening the bearing housing 2 and the compressor housing 3 together, a diffuser flow path 32 is formed between them. The diffuser flow path 32 pressurizes the air taken in from the intake port 31 . The diffuser flow path 32 has an annular shape extending from the inside to the outside in a radial direction perpendicular to the axial direction of the shaft 6 , and its inner end communicates with the intake port 31 via the compressor wheel 5 .

In addition, the compressor housing 3 is provided with a compressor scroll passage 33 . The compressor scroll channel 33 is radially outside the diffuser channel 32 and has an annular shape. The compressor scroll flow path 33 communicates with the diffuser flow path 32 and the intake passage leading to the cylinders of the internal combustion engine.

When the compressor wheel 5 rotates, air is drawn into the compressor housing 3 through the intake port 31 . The air is accelerated by the action of centrifugal force in the process of circulating between the blades of the compressor wheel 5 . The accelerated air is pressurized in the diffuser flow path 32 and the compressor scroll flow path 33 and guided to the intake passage of the internal combustion engine.

An exhaust port 11 opens in the turbine housing 1 . Further, the turbine housing 1 is formed with an exhaust passage 12 and a turbine scroll passage 13 . The turbine scroll passage 13 is radially outside the exhaust passage 12 and has an annular shape. The turbine scroll channel 13 communicates with the exhaust channel 12 and an exhaust passage communicating with the cylinders of the internal combustion engine.

Exhaust gas discharged from a cylinder of the internal combustion engine and guided to the turbine scroll passage 13 reaches the exhaust port 11 via the exhaust passage 12 and the turbine wheel 4 . The exhaust rotates the turbine wheel 4 in the process of circulating between the blades of the turbine wheel 4 . The rotational force of turbine wheel 4 is transmitted to shaft 6 and compressor wheel 5 to rotate them. As a result, the intake air is boosted by the rotational force of the compressor wheel 5 and supplied to the cylinders of the internal combustion engine.

FIG. 2 shows the structure of the bearing of the exhaust turbosupercharger in this embodiment. The bearing housing 2 is provided with an oil supply passage 23 for supplying lubricating oil to the semi-floating bearing. The oil supply passage 23 communicates with a bearing hole 22 also formed in the bearing housing 2 , and lubricating oil flows into the bearing hole 22 from the oil supply passage 23 .

A bearing metal 7, which is an element of the semi-floating bearing, has a tubular shape into which the shaft 6 can be inserted. A plurality of bearing surfaces 71 are formed on the inner peripheral surface of the bearing metal 7 so as to be very close to the outer peripheral surface of the shaft 6 . Those bearing surfaces 71 are spaced apart from each other along the axial direction. An oil hole 72 radially penetrates through the peripheral wall of the bearing metal 7 at a predetermined location facing the oil supply passage 23 . A part of the lubricating oil supplied to the bearing hole 22 from the oil supply passage 23 flows into the inner space of the bearing metal 7 through the oil hole 72 and enters the gap between the outer peripheral surface of the shaft 6 and the bearing surface 71 of the bearing metal 7. . The shaft 6 is pivotally supported by the oil film pressure of the lubricating oil.

A plurality of damper surfaces 73 are formed on the outer peripheral surface of the bearing metal 7 so as to be very close to the inner peripheral surface of the bearing hole 22 of the bearing portion 21 . These damper surfaces 73 are axially spaced apart from each other. A part of the lubricating oil supplied from the oil supply passage 23 to the bearing hole 22 enters the gap between the damper surface 73 of the bearing metal 7 and the inner peripheral surface of the bearing hole 22 . Vibration of the shaft 6 is suppressed by the oil film pressure of the lubricating oil.

A pin hole 74 is drilled at a predetermined location on the peripheral wall of the bearing metal 7 . The pin hole 74 opens at least on the outer peripheral surface of the bearing metal 7 . In this embodiment, the pin hole 74 is a through hole penetrating the peripheral wall of the bearing metal 7 along the radial direction, and the pin hole 74 also opens to the inner peripheral surface of the bearing metal 7 .

A through hole 24 radially penetrates through the peripheral wall of the bearing housing 2 at a predetermined location facing the pin hole 74 of the bearing metal 7 in the peripheral wall of the bearing portion 21 of the bearing housing 2 . The through hole 24 has an inner diameter of an outer region 242 that opens to the outer peripheral surface of the peripheral wall of the bearing portion 21 than an inner diameter of an inner region 241 that opens to the inner peripheral surface of the peripheral wall of the bearing portion 21, i.e., the bearing hole 22 side. It is large, and there is a step between the inner area 241 and the outer area 242 . Furthermore, the inner periphery of the outer region 242 of the through hole 24 is internally threaded.

Unlike the full-floating bearing, in the semi-floating bearing, the relative displacement of the bearing metal 7 arranged in the bearing hole 22 with the shaft 6 inserted therethrough relative to the bearing portion 21 of the bearing housing 2 along the axial direction and the relative displacement around the axis. Regulate rotation. For this purpose, the pin 8 for positioning the bearing metal 7 with respect to the bearing housing 2 is press-fitted from the outside of the bearing portion 21 into the inner region 241 of the through hole 24 and inserted into the pin hole 74 of the bearing metal 7 .

The pin 8 has a shaft portion 81 having a length close to the sum of the thickness of the peripheral wall of the bearing portion 21 and the thickness of the peripheral wall of the bearing metal 7 and a head portion 82 connected to the shaft portion 81 . The outer diameter of the shaft portion 81 is set to a size that is closely fitted to the inner circumference of the inner region 241 of the through hole 24 and does not easily come out of the through hole 24 . The outer diameter of the head portion 82 is larger than the outer diameter of the shaft portion 81 , and there is a step between the shaft portion 81 and the head portion 82 .

When assembling the pin 8 to the bearing portion 21 and the bearing metal 7 , the shaft portion 81 is inserted into the through hole 24 and the pin hole 74 from the outside of the bearing portion 21 . While the shaft portion 81 of the pin 8 is press-fitted into the inner region 241 of the through-hole 24 , the head portion 82 has a larger diameter than the inner region 241 of the through-hole 24 . cannot invade. In other words, the head portion 82 of the pin 8 contacts the step between the inner region 241 and the outer region 242 of the through-hole 24, and the pin 8 moves further inward (toward the central axis of the shaft 6). It becomes a stopper that prevents it from entering.

A female threaded hole 83 opening toward the head 82 is formed in the pin 8 in advance so that the pin 8 can be removed and the turbocharger can be dismantled when inspecting or repairing the exhaust turbocharger. The pin 8 can be extracted from the pin hole 74 and the through hole 24 by screwing a tool into the female screw hole 83 , gripping the tool, and strongly pulling it outward.

In addition, in the present embodiment, the outer region 242 of the through hole 24 is provided with a through hole 242 in order to reliably prevent the pin 8 from escaping from the inner region 241 of the through hole 24 and dropping to the outside of the bearing portion 21 . A bolt 9 is screwed to close the hole 24 from the outside. The outer periphery of the shaft portion 91 of the bolt 9 is provided with a male thread that engages with the female thread on the inner periphery of the outer region 242 of the through hole 24 . The outer diameter of the head 92 of the bolt 9 is sufficiently larger than the outer diameter of the outer region 242 of the through hole 24 . Therefore, when the bolt 9 is screwed, the head 92 of the bolt 9 abuts against the edge of the opening of the outer region 242 of the through hole 24, preventing the bolt 9 from entering further inside. A gap exists between the head portion 82 of the pin 8 press-fitted into the inner region 241 of the through hole 24 and the shaft portion 91 of the bolt 9 screwed into the outer region 242 , and the pin 8 and the bolt 9 are separated from each other. do not come into contact with

In this embodiment, a shaft 6 that connects a turbine wheel 4 and a compressor wheel 5 of the exhaust turbocharger is supported in the bearing housing 2, and has a cylindrical shape through which the shaft 6 is inserted. a bearing portion 21 having a bearing hole 22 provided in the bearing housing 2 and into which the shaft 6 and the bearing metal 7 are inserted, and having a through hole 24 formed in the peripheral wall thereof; A pin 8 that is inserted into the through hole 24 and the pin hole 74 to prevent the bearing metal 7 from axially moving relative to the bearing housing 2 and from rotating relative to the bearing housing 2; The structure of the bearing is constructed with a bolt 9 screwed into the hole 24 from the outside.

According to this embodiment, it is possible to appropriately prevent the pin 8 that positions the bearing metal 7 from being pulled out in the semi-floating bearing.

The present invention is not limited to the embodiments detailed above. The specific configuration of each part can be modified in various ways without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to an exhaust gas turbocharger for an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 2... Bearing housing 21... Bearing part 22... Bearing hole 24... Through hole 4... Turbine wheel 5... Compressor wheel 6... Shaft 7... Bearing metal 74... Pin hole 8... Pin 9... Bolt

Claims (1)

A structure in which a shaft connecting a turbine wheel and a compressor wheel of an exhaust turbocharger is supported in a bearing housing,
a bearing metal having a cylindrical shape through which the shaft is inserted and having pin holes drilled in its peripheral wall;
a bearing portion provided in the bearing housing and including a bearing hole into which the shaft and the bearing metal are inserted and having a through hole formed in the peripheral wall thereof;
a pin that is inserted into the through hole and the pin hole to prevent the bearing metal from axially displacing relative to the bearing housing and from rotating relative to the bearing housing;
A bolt separate from the pin is screwed from the outside into the through hole into which the pin is inserted to close the through hole, and the bearing housing has an oil supply path communicating with the bearing hole. A bearing structure that is formed separately from the through hole .

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