JP2007113708A - Rotation stop structure of bearing, and supercharger using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation stop structure of a bearing and a supercharger using the rotation stop structure having excellent durability and high effect of suppressing vibration of the bearing. <P>SOLUTION: An intake turbine, a shaft for supporting the intake turbine, and a bearing structure for supporting the shaft, are provided, and the bearing structure is provided with the rotation stop structure of the bearing. As the rotation stop structure of the bearing, the bearing 17, and a bearing housing 16 (a bearing base) for supporting the bearing 17 are provided. The bearing housing 16 is provided with an insertion port into which the bearing 17 is coaxially inserted. A fluid space 22 for storing a fluid is provided between the inner peripheral surface of the insertion port 21 and the outer peripheral surface of the bearing 17 to constitute a squeeze film damper. The inner peripheral surface of the insertion port 21 and the outer peripheral surface of the bearing 17 are respectively formed in elliptic shape from the axial view, and the largest diameter part of the bearing 17 is made larger than the smallest diameter part of the insertion port 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing detent structure, particularly a bearing detent structure that supports a shaft that rotates at a high speed, and a turbocharger that uses this bearing detent structure.

Examples of the machine using the bearing include a supercharger used for an internal combustion engine such as a ship, an automobile, and a generator engine.
The supercharger improves combustion efficiency by forcibly supplying air into the combustion chamber of the internal combustion engine, thereby improving the output of the internal combustion engine.
As the supercharger, for example, an exhaust turbo type supercharger is known. An exhaust turbocharger includes an exhaust turbine that is rotationally driven by exhaust gas of an internal combustion engine, an intake turbine that is driven by the exhaust turbine, a shaft that connects the exhaust turbine and the intake turbine, and a bearing that supports the shaft. Structure. As the bearing structure, a bearing structure having a bearing (for example, a slide bearing) that supports a shaft and a bearing base that supports the bearing is used.
In the exhaust turbocharger, the exhaust turbine is rotationally driven by the exhaust gas, so that the intake turbine connected to the exhaust turbine via the shaft portion is rotationally driven so that the external air is pumped by the intake turbine. It has become.

When the rotational speed of the rotating body is very high, such as a shaft of a supercharger, a squeeze film damper is provided in the bearing structure in order to ensure the rotational stability of the rotating body.
The squeeze film damper is formed by forming a very small fluid space between the outer peripheral surface of the bearing that receives the rotating body and the bearing base that supports the bearing, and filling the fluid space with a fluid such as oil. .
In the squeeze film damper, when the bearing is displaced in the radial direction and the outer peripheral surface of the bearing is close to the bearing base, the fluid in the fluid space is compressed at this portion, and the pressure of the fluid rises. Pushed back. That is, in the squeeze film damper, the bearing is always urged toward an appropriate position by the fluid pressure in the fluid space, so that vibration in the radial direction of the bearing is suppressed.

Here, since viscous friction arises between a rotary body and a bearing, when a rotary body is rotated, rotational force will be added to a bearing. For this reason, the bearing is provided with a locking pin that engages with the bearing base and restricts rotation about the axis of the bearing so as not to rotate with the rotating body.
However, when the rotational speed of the rotating body is very fast, such as the shaft of a supercharger, a large load is applied to the locking pin because the rotational force and vibration applied to the bearing are large. For this reason, it has been necessary to perform maintenance of the locking pin so that the locking pin is not broken due to wear, metal fatigue, or the like.

In order to save such maintenance work, a bearing detent structure with excellent durability is required instead of a bearing detent structure using a locking pin.
As a bearing detent structure, for example, a bearing structure for a rotating machine described in Patent Document 1 is known. In this bearing structure for a rotating machine, a protrusion is formed along the axial direction on the outer periphery of an outer ring of a bearing (ball bearing), or the outer ring is formed into a polygonal shape.

Registered Utility Model No. 3006563

  However, the technical idea of Patent Document 1 is to prevent rotation of the bearing by engaging protrusions and corners provided on the outer periphery of the bearing with the bearing base. For this reason, the bearing structure for a rotating machine described in Patent Document 1 cannot be applied to a bearing structure using a squeeze film damper that needs to allow a certain amount of displacement of the bearing.

In addition, in a bearing structure using a squeeze film damper, if a protrusion is provided on the outer periphery of the bearing or the outer shape of the bearing is a polygonal shape, the bearing is And the bearing stand are in line contact. Then, since the contact surface pressure between the bearing and the bearing base increases, the bearing and the bearing base are likely to be worn.
Furthermore, in a bearing structure using a squeeze film damper, the thickness of the fluid space formed between the outer peripheral surface of the bearing and the bearing base when a protrusion is provided on the outer periphery of the bearing or the outer ring is formed in a polygonal shape. Depending on the direction of displacement of the bearing, the thickness of the fluid space on the displaced side of the bearing is too large, and the fluid pressure generated on the displaced side of the bearing in the fluid space (i.e., the bearing The pushing back force) cannot be sufficiently increased, and it becomes difficult to suppress the vibration of the bearing.

  Further, as the rotating body rotates, the displacement direction of the bearing sequentially moves in the circumferential direction. That is, when the rotating body rotates, the bearing moves circularly when viewed from the axial direction. For this reason, when the protrusion is provided on the outer periphery of the bearing as described above, or when the outer shape of the bearing is a polygonal shape, the protrusion is not moved from the state in which the bearing is displaced in the direction in which the protrusion or the corner is provided. When shifting to a state where the corners are not provided, or when the bearing is displaced in a direction where the protrusions or corners are not provided, the bearing is displaced in the direction where the protrusions or corners are provided. When shifting to the state, a large fluctuation occurs in the fluid pressure generated in the fluid space, and it becomes difficult to suppress the vibration of the bearing.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a bearing detent structure having excellent durability and high bearing vibration suppression effect, and a supercharger using the same. To do.

In order to solve the above problems, the present invention provides the following means.
That is, the present invention includes a bearing and a bearing base that supports the bearing, and the bearing base is provided with an insertion port into which the bearing is inserted coaxially, and an inner periphery of the insertion port is provided. A fluid space for storing fluid is provided between the surface and the outer peripheral surface of the bearing, and the support structure of the bearing by the bearing base constitutes a squeeze film damper. A bearing detent structure in which a peripheral surface and an outer peripheral surface of the bearing are each formed in an elliptical shape when viewed from the axial direction, and a maximum diameter portion of the bearing is larger than a minimum diameter portion of the insertion port. provide.

In the bearing detent structure configured as described above, the inner peripheral surface of the insertion port into which the bearing is inserted and the outer peripheral surface of the bearing are formed in an elliptical shape when viewed from the axial direction. The diameter portion is larger than the minimum diameter portion of the insertion opening.
For this reason, even when a rotational force is applied to the bearing, the maximum diameter portion of the bearing is received by the inner peripheral surface of the insertion port, and the circumferential rotation of the bearing is restricted.

In the bearing detent structure according to the present invention, the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing are each formed in an elliptical shape when viewed from the axial direction. Compared to the case where it is circular or polygonal when viewed from the direction, the contact area when the outer peripheral surface of the bearing comes into contact with the inner peripheral surface of the insertion port is large. The contact surface pressure becomes lower.
For this reason, the anti-rotation structure of the bearing of the present invention is less likely to be worn on the bearing and the bearing base (inner surface of the insertion port), and is excellent in durability.
Furthermore, in the bearing rotation preventing structure of the present invention, the squeeze film damper is formed over the entire circumference of the outer peripheral surface of the bearing, and the effective area of the squeeze film damper is large, so that the vibration suppression effect of the bearing is high.

In the bearing rotation preventing structure of the present invention, the entire outer peripheral surface of the bearing and the entire inner peripheral surface of the insertion port are each formed in an elliptical shape (smooth closed curve) when viewed from the axial direction. And the thickness of the fluid space formed between the inner peripheral surface of the insertion port is substantially uniform over the entire circumference around the axis.
For this reason, in the bearing detent structure of the present invention, no matter which direction the bearing is displaced relative to the bearing base, the fluid pressure generated on the side where the bearing is displaced in the fluid space (ie, the force that regulates the displacement of the bearing). ) Is almost constant, so the bearing vibration suppressing effect is high.

Moreover, in the rotation prevention structure of the bearing of this invention, a bearing moves along the internal peripheral surface of an insertion port because the rotary body which a bearing supports rotates. That is, when the rotating body rotates, the bearing performs an elliptical motion as viewed from the axial direction.
In the bearing detent structure of the present invention, the entire outer peripheral surface of the bearing and the entire inner peripheral surface of the insertion port are each formed in an elliptical shape (smooth closed curve shape) when viewed from the axial direction. The fluctuation of fluid pressure generated in the fluid space is small. For this reason, in the bearing locking structure of the present invention, the vibration of the bearing can be effectively suppressed.

  The present invention also includes a bearing and a bearing base that supports the bearing, and the bearing base is provided with an insertion port into which the bearing is inserted coaxially, and an inner periphery of the insertion port is provided. A fluid space for storing fluid is provided between the surface and the outer peripheral surface of the bearing, and the support structure of the bearing by the bearing base constitutes a squeeze film damper. The peripheral surface and the outer peripheral surface of the bearing are each formed in a similar multi-arc shape when viewed from the axial direction, and the maximum diameter portion of the bearing is larger than the minimum diameter portion of the insertion port. Provide a detent structure.

In the bearing detent structure configured as described above, the inner peripheral surface of the insertion port into which the bearing is inserted and the outer peripheral surface of the bearing are formed in a multi-arc shape when viewed from the axial direction. The maximum diameter portion is larger than the minimum diameter portion of the insertion opening.
For this reason, even when a rotational force is applied to the bearing, the maximum diameter portion of the bearing is received by the inner peripheral surface of the insertion port, and the circumferential rotation of the bearing is restricted.

In the bearing detent structure according to the present invention, the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing are each formed in a multi-arc shape when viewed from the axial direction, so the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing are The contact area when the outer peripheral surface of the bearing is in contact with the inner peripheral surface of the insertion port is larger than that when each of them is circular or polygonal when viewed from the axial direction. The contact surface pressure with the inner surface is lowered.
For this reason, the anti-rotation structure of the bearing of the present invention is less likely to be worn on the bearing and the bearing base (inner surface of the insertion port), and is excellent in durability.
Furthermore, in the bearing rotation preventing structure of the present invention, the squeeze film damper is formed over the entire circumference of the outer peripheral surface of the bearing, and the effective area of the squeeze film damper is large, so that the vibration suppression effect of the bearing is high.

In the bearing detent structure according to the present invention, the entire outer peripheral surface of the bearing and the entire inner peripheral surface of the insertion port are each formed in a shape in which a plurality of smooth curves are connected as viewed from the axial direction. The thickness of the fluid space formed between the surface and the inner peripheral surface of the insertion port is substantially uniform over the entire circumference around the axis.
For this reason, in the anti-rotation structure of the bearing according to the present invention, the fluid pressure (that is, the displacement of the bearing) generated on the side where the bearing is displaced in the fluid space, regardless of the direction in which the bearing is displaced relative to the bearing base, is regulated. The force) is almost constant, so the bearing vibration suppression effect is high.

Moreover, in the rotation prevention structure of the bearing of this invention, a bearing moves along the internal peripheral surface of an insertion port because the rotary body which a bearing supports rotates.
In the bearing detent structure of the present invention, the entire outer peripheral surface of the bearing and the entire inner peripheral surface of the insertion port are each formed in a multi-arc shape (a shape in which a plurality of smooth curves are connected) as viewed from the axial direction. The fluctuation of the fluid pressure generated in the fluid space in the process of movement is small. For this reason, in the bearing locking structure of the present invention, the vibration of the bearing can be effectively suppressed.

  The present invention also includes a bearing and a bearing base that supports the bearing, and the bearing base is provided with an insertion port into which the bearing is inserted coaxially, and an inner periphery of the insertion port is provided. A fluid space for storing fluid is provided between the surface and the outer peripheral surface of the bearing, and the bearing support structure by the bearing base constitutes a squeeze film damper, and the insertion port A key that engages with the inner peripheral surface and the outer peripheral surface of the bearing; and a key groove that is provided on at least one of the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing to receive the key. A play is provided between the key groove and the key, and an inner surface of the key groove and a facing surface facing the key groove inner surface of the key are curved when viewed from the axial direction of the bearing. The curvature of the opposite surface of the key is half But it provides a detent structure of the corresponding keyway in the inner surface smaller bearing than the radius of curvature of.

In the bearing detent structure configured as described above, a key that engages with these is provided between the inner surface of the insertion port of the bearing base and the outer peripheral surface of the bearing. Even when added, rotation of the bearing in the circumferential direction is restricted.
In the bearing rotation preventing structure of the present invention, a key groove for receiving the key is provided on at least one of the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing. In the bearing detent structure according to the present invention described above, unlike a general coupling structure using a key, play is provided between the key groove and the key. Thereby, the restraint of the bearing position by the key becomes loose, and the squeeze film damper acts effectively.
Moreover, this play becomes a fluid space constituting the squeeze film damper. That is, in the bearing rotation preventing structure of the present invention, the squeeze film damper is formed over the entire outer peripheral surface of the bearing, and the effective area of the squeeze film damper is large.
From the above, the bearing rotation preventing structure of the present invention has a high bearing vibration suppressing effect.

In the bearing detent structure according to the present invention, the inner surface of the key groove and the opposing surface of the key that faces the inner surface of the key groove are formed in a curved shape when viewed from the axial direction of the bearing. The radius of curvature of the opposite surface of the key is set to be smaller than the radius of curvature of the inner surface of the corresponding key groove.
Thereby, in the rotation prevention structure of the bearing according to the present invention, when the key comes into contact with the bottom surface of the key groove due to the vibration of the bearing, the key groove and the key come into contact with each other on the curved surfaces. The contact surface pressure is lowered correspondingly.
For this reason, the anti-rotation structure for a bearing according to the present invention is excellent in durability because the bearing, the bearing stand (the inner surface of the insertion port), and the key are hardly worn.

Here, in the anti-rotation structure of each of the bearings, a bush that is a separate member from the bearing base body is fixedly provided on the bearing base, and the insertion port may be formed in the bush. .
In this way, instead of providing an insertion port in the bearing stand, the insertion port is formed in a bush that is a separate member from the bearing stand, so that the bush can be attached to the bearing stand regardless of the shape of the bearing stand. An insertion port can be provided on the table, which facilitates manufacturing.
Even if the inner peripheral surface of the insertion opening is worn, the performance can be recovered by replacing the bush.

Further, the present invention includes an intake turbine, a shaft that supports the intake turbine, and a bearing structure that supports the shaft, and the bearing structure includes the above-described bearing detent structure according to the present invention. A turbocharger having any one of the structures is provided.
In the turbocharger configured as described above, the bearing structure that supports the shaft has the bearing detent structure according to the present invention, so that the bearing structure has high durability and the bearing vibration suppression effect. high.

  According to the bearing detent structure configured as described above and the supercharger using the same, the durability of the bearing structure is high and the vibration suppression effect of the bearing is high.

Embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.
In this embodiment, an example in which the present invention is applied to an exhaust turbocharger will be described.
As shown in FIG. 1, a supercharger 1 is provided on an exhaust gas discharge path of an internal combustion engine and is driven by exhaust gas. The supercharger 1 is driven by the exhaust gas turbine 2 to drive outside air to the internal combustion engine. And a compressor 3 that pumps the fuel into the combustion chamber.

  The exhaust turbine apparatus 2 includes an exhaust turbine housing 6 in which a spiral flow path S and a turbine storage chamber T connected to the innermost peripheral portion of the spiral flow path S are provided, and a substantially radial center of the turbine storage chamber T. An exhaust turbine 7 (turbine impeller) provided with a spiral flow path S and an axis substantially parallel to each other, and a shaft 8 connected substantially coaxially with the exhaust turbine 7 on the compressor 3 side in the axial direction of the exhaust turbine 7 have.

The compressor 3 includes an intake turbine housing 11 in which a spiral flow path is formed, and an intake turbine 12 (compressor impeller) provided at a substantially central portion in the radial direction of the intake turbine housing 11.
The exhaust turbine 7 of the exhaust turbine device 2 and the intake turbine 12 of the compressor 3 are connected substantially coaxially by a shaft 8. Between the exhaust turbine housing 6 and the intake turbine housing 11, a bearing housing 16 (bearing stand) is provided adjacent to the exhaust turbine housing 6 and the intake turbine housing 11.
The bearing housing 16 is provided with a bearing 17 that supports the shaft 8 so as to be rotatable about an axis, and a lubrication system 18 that supplies lubricating oil to the bearing 17.
In the present embodiment, a slide bearing is used as the bearing 17.

As schematically shown in FIG. 2, the bearing housing 16 is provided with an insertion port 21 into which the bearing 17 is inserted coaxially. A fluid space 22 in which a fluid such as oil is stored is provided between the inner peripheral surface of the insertion port 21 and the outer peripheral surface of the bearing 17. That is, the support structure of the bearing 17 by the bearing housing 16 constitutes a squeeze film damper.
The inner peripheral surface of the insertion port 21 and the outer peripheral surface of the bearing 17 are each formed in an elliptical shape when viewed from the axial direction. The maximum diameter portion of the bearing 17 (portion positioned on the long axis X when viewed from the axial direction) is larger than the minimum diameter portion of the insertion port 21 (portion positioned on the short axis Y when viewed from the axial direction). Yes.
In the present embodiment, the outer peripheral portion of the bearing 17 and the inner peripheral portion of the insertion port 21 constitute a rotation preventing structure for the bearing 17.

In the supercharger 1, the inner peripheral surface of the insertion port 21 into which the bearing 17 is inserted in the bearing housing 16 and the outer peripheral surface of the bearing 17 are each formed in an elliptical shape when viewed from the axial direction, and the maximum diameter of the bearing 17. The portion has a larger diameter than the minimum diameter portion of the insertion opening.
For this reason, even when a rotational force is applied to the bearing 17, the maximum diameter portion of the bearing 17 is received by the inner peripheral surface of the insertion port 21, and the rotation of the bearing 17 in the circumferential direction is restricted.

In this supercharger 1, since the inner peripheral surface of the insertion port 21 and the outer peripheral surface of the bearing 17 are each formed in an elliptical shape when viewed from the axial direction, the outer periphery of the bearing 17 is indicated by a two-dot chain line in FIG. The contact area when the surface comes into contact with the inner peripheral surface of the insertion port 21 is compared to the case where the inner peripheral surface of the insertion port 21 and the outer peripheral surface of the bearing 17 are each made circular when viewed from the axial direction or in a polygonal shape. The contact pressure between the outer peripheral surface of the bearing 17 and the inner surface of the insertion port 21 is reduced correspondingly.
For this reason, this supercharger 1 is less likely to be worn on the bearing 17 and the bearing housing 16 (the inner surface of the insertion port 21), and is excellent in durability.
Furthermore, in this supercharger 1, since the squeeze film damper is formed over the entire outer periphery of the bearing 17, and the effective area of the squeeze film damper is large, the vibration suppressing effect of the bearing 17 is high.

In the supercharger 1, the entire outer peripheral surface of the bearing 17 and the entire inner peripheral surface of the insertion port 21 are each formed in an elliptical shape (smooth closed curve) when viewed from the axial direction. And the thickness of the fluid space 22 formed between the inner peripheral surface of the insertion port 21 is substantially uniform over the entire circumference around the axis.
For this reason, in this supercharger 1, no matter which direction the bearing 17 is displaced relative to the bearing housing 16, the fluid pressure generated on the side where the bearing 17 is displaced in the fluid space 22 (that is, the displacement of the bearing 17 is regulated). The force to suppress the vibration of the bearing 17 is high.

In the supercharger 1, the shaft 17 supported by the bearing 17 rotates, so that the bearing 17 moves along the inner peripheral surface of the insertion port 21. That is, when the shaft 8 rotates, the bearing 17 performs an elliptical motion as viewed from the axial direction.
In this supercharger 1, the entire outer peripheral surface of the bearing 17 and the entire inner peripheral surface of the insertion port 21 are each formed in an elliptical shape (smooth closed curve) when viewed from the axial direction. Thus, the fluctuation of the fluid pressure generated on the side where the bearing 17 is displaced in the fluid space 22 is small (in other words, the fluid pressure generated on the side where the bearing 17 is displaced in the fluid space 22 can only suppress the displacement of the bearing 17. Maintained at high pressure).
For this reason, in this supercharger 1, the vibration of the bearing 17 can be suppressed effectively.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
The supercharger 31 shown in this embodiment is obtained by changing the structure for preventing rotation of the bearing in the supercharger 1 shown in the first embodiment.
Specifically, in the supercharger 31 according to the present embodiment, in the supercharger 1, the outer peripheral surface has a multi-arc shape when viewed from the axial direction, instead of the bearing 17 whose outer peripheral surface has an elliptical shape when viewed from the axial direction. Instead of the bearing housing 16 using the formed bearing 32 and having the insertion port 21 whose inner peripheral surface is elliptical when viewed from the axial direction, a multi-circular arc whose inner peripheral surface is similar to the outer peripheral surface of the bearing 32 when viewed from the axial direction. A bearing housing 34 having an insertion port 33 having a shape is used.
A fluid space 35 in which fluid such as oil is stored is provided between the inner peripheral surface of the insertion port 33 and the outer peripheral surface of the bearing 32. That is, the support structure of the bearing 32 by the bearing housing 34 constitutes a squeeze film damper.
The maximum diameter portion of the bearing 32 is larger than the minimum diameter portion of the insertion port 33.

Here, the multi-arc shape is a shape in which a plurality of arcs having different directions are connected so as to draw a closed curve. In the present embodiment, the outer peripheral surface of the bearing 32 and the inner peripheral surface of the insertion port 33 are each formed in a three-arc shape when viewed from the axial direction (that is, a closed curve shape in which three arcs having the same shape and different directions by 120 ° are connected). ).
The maximum diameter of the bearing 32 whose outer peripheral surface forms a three-arc shape is the dimension of the bearing 32 along a straight line connecting one of the connecting portions of the arc and the axis. Further, the minimum diameter of the insertion port 33 whose inner peripheral surface forms a three-arc shape is equal to the diameter of a circle inscribed in the three-arc shape formed by the inner peripheral surface.

In the supercharger 31, the inner peripheral surface of the insertion port 33 into which the bearing 32 is inserted in the bearing housing 34 and the outer peripheral surface of the bearing 32 are formed in a three-arc shape when viewed from the axial direction. The diameter portion is larger than the minimum diameter portion of the insertion port 33.
For this reason, even when a rotational force is applied to the bearing 32, the maximum diameter portion of the bearing 32 is received by the inner peripheral surface of the insertion port, and the rotation of the bearing 32 in the circumferential direction is restricted.

In the supercharger 31, the inner peripheral surface of the insertion port 33 and the outer peripheral surface of the bearing 32 are each formed in a three-arc shape when viewed from the axial direction, so the inner peripheral surface of the insertion port 33 and the outer peripheral surface of the bearing 32 are formed. The contact area when the outer peripheral surface of the bearing 32 comes into contact with the inner peripheral surface of the insertion port 33 is larger than the case where each is circular when viewed from the axial direction or the polygonal shape. And the contact surface pressure with the inner surface of the insertion port 33 is lowered.
For this reason, the supercharger 31 is less likely to be worn on the bearing 32 and the bearing housing 34 (the inner surface of the insertion port 33), and is excellent in durability.
Furthermore, in this supercharger 31, since the squeeze film damper is formed over the entire outer periphery of the bearing 32, and the effective area of the squeeze film damper is large, the vibration suppressing effect of the bearing 32 is high.

Moreover, in this supercharger 31, since the whole outer peripheral surface of the bearing 32 and the whole inner peripheral surface of the insertion port 33 are each formed in the shape which connected the smooth curve seeing from the axial direction, The thickness of the fluid space 35 formed between the inner peripheral surface of the insertion port 33 is substantially uniform over the entire circumference around the axis.
For this reason, in this supercharger 31, no matter which direction the bearing 32 is displaced with respect to the bearing housing 34, the fluid pressure generated on the side where the bearing 32 is displaced in the fluid space 35 (that is, the displacement of the bearing 32 is regulated). The force to suppress the vibration of the bearing 32 is high.

In the supercharger 31, the shaft 32 supported by the bearing 32 rotates, so that the bearing 32 moves along the inner peripheral surface of the insertion port 33.
In the supercharger 31, the entire outer peripheral surface of the bearing 32 and the entire inner peripheral surface of the insertion port 33 are each formed in a three-arc shape (a shape in which a plurality of smooth closed curves are connected) as viewed from the axial direction. The fluctuation of the fluid pressure generated in the fluid space 35 in the course of the movement is small. For this reason, in this supercharger 31, the vibration of the bearing 32 can be suppressed effectively.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS.
The supercharger 51 shown in the present embodiment is obtained by changing the structure for preventing rotation of the bearing in the supercharger 1 shown in the first embodiment.
Specifically, the supercharger 51 according to the present embodiment uses a bearing 52 instead of the bearing 17 in the supercharger 1 and a bearing housing 54 having an insertion port 53 instead of the bearing housing 16. It is.
A fluid space 55 in which a fluid such as oil is stored is provided between the outer peripheral surface of the bearing 52 and the inner peripheral surface of the insertion port 53. That is, the support structure of the bearing 52 by the bearing housing 54 constitutes a squeeze film damper.

The supercharger 51 includes at least one of a key 61 that engages with the inner peripheral surface of the insertion port 53 and the outer peripheral surface of the bearing 52, and the inner peripheral surface of the insertion port 53 and the outer peripheral surface of the bearing 52. A key groove 62 is provided on either side for receiving the key 61.
Here, the key groove 62 may be provided only on the outer peripheral surface of the bearing 52, may be provided only on the inner peripheral surface of the insertion port 53, or may be provided on both the outer peripheral surface and the inner peripheral surface. Good.
In the present embodiment, a key groove 62a is provided on the outer peripheral surface of the bearing 52, and a key groove 62b is provided on the inner peripheral surface of the insertion port 53 at a position facing the key groove 62a. The key 61 is provided so as to straddle these key grooves 62.
As shown in FIG. 5 (AA arrow cross-sectional view in FIG. 4), the key groove 62 a of the bearing 52 extends from the end of the insertion port 53 in the insertion direction to the vicinity of the other end along the axis of the bearing 52. Is provided. The keyway 62 b of the insertion port 53 is formed with a length shorter than the entire length of the insertion port 53 along the axis of the insertion port 53 from the opening end of the insertion port 53.
As a result, in a state where the bearing 52 is inserted into the insertion port 53, the key 61 is sandwiched between the end of the key groove 62 a of the bearing 52 and the end of the key groove 62 b of the insertion port 53, and the key 52 is dropped from the key groove 62. Is prevented.

The key 61 is fitted into the key groove 62 b of the insertion port 53, while an play is provided between the key 61 and the key groove 62 a of the bearing 52.
The inner surface of the key groove 62a of the bearing 52 and the opposing surface that faces the inner surface of the key groove 62a of the key 61 are formed in a curved shape when viewed from the axial direction of the bearing 52, and the curvature radius of the opposing surface of the key 61 corresponds. The radius of curvature of the inner surface of the key groove 62 is smaller.

In the supercharger 51 configured as described above, the key 61 that engages with the inner surface of the insertion port 53 of the bearing housing 54 and the outer peripheral surface of the bearing 52 is provided. Even when a rotational force is applied, rotation of the bearing 52 in the circumferential direction is restricted.
In the supercharger 51, a key groove 62 a that receives the key 61 is provided on the outer peripheral surface of the bearing 52, and play is provided between the key groove 62 a and the key 61. Thereby, the restraint of the position of the bearing 52 by the key 61 becomes loose, and the squeeze film damper acts effectively.
In addition, the play between the key 61 and the key groove 62a becomes a fluid space 55 constituting a squeeze film damper. That is, in the supercharger 51, a squeeze film damper is formed over the entire outer peripheral surface of the bearing 52, and the effective area of the squeeze film damper is large.
From the above, this supercharger 51 has a high vibration suppression effect of the bearing 52.

In the supercharger 51, the inner surface of the key groove 62 a of the bearing 52 and the opposing surface of the key 61 that faces the inner surface of the key groove 62 a are formed in a curved shape when viewed from the axial direction of the bearing 52. The curvature radius of the opposing surface of the key 61 is set smaller than the curvature radius of the inner surface of the corresponding key groove 62a.
Thereby, in this supercharger 51, when the key 61 comes into contact with the bottom surface of the key groove 62a due to the vibration of the bearing 52, the key groove 62a and the key 61 come into contact with each other between the curved surfaces. The contact surface pressure is reduced accordingly.
For this reason, the supercharger 51 is less likely to be worn on the bearing 52, the bearing housing 54 (the inner surface of the insertion port 53), and the key 61, and is excellent in durability.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The supercharger 71 shown in the present embodiment is obtained by changing the bearing rotation prevention structure in the supercharger 31 shown in the second embodiment.
Specifically, the supercharger 71 according to the present embodiment is based on a bearing housing main body 72 formed by casting or the like instead of the bearing housing 34 in which the insertion port 33 is directly provided in the supercharger 31. A bearing housing 74 is used in which a bush 73 provided with an insertion port 33 is fixedly provided.
Here, the bush 73 is attached to an attachment hole provided in the bearing housing main body 72 by, for example, an interference fit such as shrink fitting, or attached to the bearing housing main body 72 by spot welding or the like.
In the present embodiment, the bush 73 has a cylindrical shape in which the insertion port 33 is provided along the axis, and is attached to a round hole-like mounting hole 72 a provided in the bearing housing body 72 by shrink fitting. ing.

In this supercharger 71, only by attaching the bush 73 to the bearing housing main body 72, the insertion port 33 can be provided in the bearing housing 74 regardless of the shape of the bearing housing 74, and the manufacture becomes easy.
Even if the inner circumferential surface of the insertion port 33 is worn, the performance can be recovered by replacing the bush 73.

It is a longitudinal section showing the composition of the supercharger concerning a first embodiment of the present invention. 1 is an axial cross-sectional view showing a bearing detent structure according to a first embodiment of the present invention. It is an axial orthogonal cross section which shows the rotation prevention structure of the bearing of the supercharger which concerns on 2nd embodiment of this invention. It is an axial orthogonal cross section which shows the rotation prevention structure of the bearing of the supercharger which concerns on 3rd embodiment of this invention. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. It is an axial orthogonal cross section which shows the rotation prevention structure of the bearing of the supercharger which concerns on 4th embodiment of this invention.

Explanation of symbols

1, 31, 51, 71 Supercharger 8 Shaft 12 Intake turbine 16, 34, 54, 74 Bearing housing (bearing base)
17, 32, 52 Bearing 21, 33, 53 Insertion port 22, 35, 55 Fluid space 61 Key 62 Key groove 72 Bearing housing body (bearing base body)
73 Bush

Claims (5)

A bearing,
A bearing stand for supporting the bearing;
The bearing base is provided with an insertion port through which the bearing is inserted coaxially,
A fluid space for storing fluid is provided between the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing, and the support structure of the bearing by the bearing base constitutes a squeeze film damper. ,
The inner peripheral surface of the insertion port and the outer peripheral surface of the bearing are each formed in an elliptical shape when viewed from the axial direction,
A bearing detent structure in which a maximum diameter portion of the bearing is larger in diameter than a minimum diameter portion of the insertion port. A bearing,
A bearing stand for supporting the bearing;
The bearing base is provided with an insertion port through which the bearing is inserted coaxially,
A fluid space for storing fluid is provided between the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing, and the support structure of the bearing by the bearing base constitutes a squeeze film damper. ,
The inner peripheral surface of the insertion port and the outer peripheral surface of the bearing are each formed in a multi-arc shape having a similar shape when viewed from the axial direction,
A bearing detent structure in which a maximum diameter portion of the bearing is larger in diameter than a minimum diameter portion of the insertion port. A bearing,
A bearing stand for supporting the bearing;
The bearing base is provided with an insertion port through which the bearing is inserted coaxially,
A fluid space for storing fluid is provided between the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing, and the support structure of the bearing by the bearing base constitutes a squeeze film damper. ,
A key that engages the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing;
A key groove provided on at least one of the inner peripheral surface of the insertion port and the outer peripheral surface of the bearing to receive the key;
A play is provided between the keyway and the key,
The inner surface of the key groove and the facing surface facing the key groove inner surface of the key are formed in a curved shape when viewed from the axial direction of the bearing,
A bearing detent structure in which the radius of curvature of the facing surface of the key is smaller than the radius of curvature of the inner surface of the corresponding key groove.   The bearing according to any one of claims 1 to 3, wherein a bush that is a separate member from the bearing base body is fixedly provided on the bearing base, and the insertion port is formed in the bush. Stop structure. An intake turbine,
A shaft that supports the intake turbine;
A bearing structure for supporting the shaft;
The supercharger in which this bearing structure has the rotation prevention structure of the bearing in any one of Claim 1 to 4.

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