JPH03279698A - Coupling construction of compressor impeller for turbocharger - Google Patents

Abstract

PURPOSE:To prevent generation of unbalance due to eccentricity for preventing vibration by contacting the back of a blower impeller with a back member provided on a rotating shaft, forming the end face of the front side part into a spherical shape, and forming the contact face of an engaging front member into a spherical form of same curvature. CONSTITUTION:The contact face 24B on the impeller 26 side of a spacer (corresponded to a back member) 24 is formed into a perpendicular face to a shaft 21, and the back 26B of the impeller 26 is contacted with this perpendicular face. The end face 26A on the front side of the impeller 26 is formed into a recessed spherical shape of a prescribed curvature, and a nut 27 having a projecting end face 27A is engagingly contacted with this end face 26A. The nut (corresponded to a front member) 27 is fitted to the shaft 21, the impeller is coupled to the shaft 21 with the nut, and the face 27A is formed into a projecting spherical shape of a same curvature as that of the end face 26A. This curvature is decided according to degree of inclination of the impeller 26 against the shaft 21 and the radius of curvature is set to be a little longer than the length of the shaft 21 projected from the impeller 26.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a compressor impeller fastening structure for a turbocharger, and more specifically, a compressor impeller fastening structure that prevents shaft bending and imbalance. Regarding.

(Prior Art) A conventional fastening structure for a compressor impeller of a turbocharger is described in, for example, Japanese Utility Model Application Publication No. 60-107392, as shown in FIG. 4.

In Fig. 4, 1 is the shaft of the compressor impeller of the turbocharger, 2 is a floating metal that rotatably supports the shaft 1, 3 is a thrust collar, 4 is a spacer, 5 is a mechanical seal, and 6 is an impeller. The thrust collar 3, spacer 4, and impeller 6 are fitted into the shaft 1, and are fastened together at a naso I.8 via a spacer 7 having a tapered end surface. Further, in this example, in order to align the center of the impeller 6 with the center of the shaft 1, the impeller 6 is centered by the spacer 4, the impeller 6, the tapered surface 7B of the spacer 7, etc.

In addition, 11 is a housing, 12 is a bearing housing, 7A
is the vertical surface of spacer 7, 7C is the end surface of spacer 7, 8A
is the tightening surface of the nut 8.

In this type of fastening structure for the compressor impeller of a turbocharger, it is difficult to connect the shaft 1 and the impeller 6 with high concentric precision, and there is also a difference in coefficient of thermal expansion when the materials of the two are different. In view of the background, in order to provide a gap between the shaft 1 and the impeller 6 while also ensuring high concentricity accuracy, the spacer 4, as described above, is used.
The impeller 6 and the tapered surface 7B of the spacer 7 are used to center the two.

In addition, as a similar prior art, for example, Utility Model Application No. 60415
There is one described in Publication No. 30. This is a connection structure between a turbine wheel and a turbine shaft in a turbocharger, and the turbine wheel is sandwiched between the tapered end surface of a nut that is screwed to the tip of the turbine shaft that passes through the mounting hole, and the turbine wheel is held at a predetermined position relative to the turbine wheel. By fastening with an axial force of It is something to do.

(Problems to be Solved by the Invention) However, in the conventional fastening structure of the compressor impeller of a turbocharger, in the case of the technique described in the former publication, first, the axis of the threaded portion of the nut 8 and nut 8
The machining accuracy of the perpendicularity with the end face on the impeller 6 side was not taken into account, and the structure did not take into account the deformation of the shaft 1 when fastened with a nut 8 with an incorrect perpendicularity. There is a problem in that unbalance occurs due to deformation of the impeller 1 and eccentricity of the impeller 6, causing large vibrations in the turbocharger.

That is, in an actual turbocharger, the machining accuracy of the perpendicularity between the axis of the threaded portion of the nut 8 and the end face of the nut 8 is significantly worse than that of the impeller 6. Therefore, for example, if the nut 8 is tightened with an incorrect perpendicularity, the shaft 1 will be deformed, and the nut 8 and impeller 6 will be fastened with eccentricity and inclination relative to the bearing part, and a large angle will be created with respect to the shaft 1. Generate a balance amount. As a result, large vibrations occur in the turbocharger.

On the other hand, the technology described in the latter publication performs centering using the tapered end surface of the nut, but it is thought that this centering technology is similar to the former, and the only difference is that the impeller is replaced by a turbine blade. It's fine. Therefore, when a turbine blade is tightened with a tapered member, the shaft will bend due to misalignment between the thread core and the tapered member, even if this technology is applied.
Similar problems occur when the amount of unbalance in the rotating body increases.

(Object of the Invention) Therefore, an object of the present invention is to provide a fastening structure for a compressor impeller of a turbocharger, which can prevent imbalance due to shaft deformation and impeller eccentricity, and can prevent turbocharger vibration. The purpose is

(Means for Solving the Problems) In order to achieve the above object, the fastening structure of the compressor impeller of the turbocharger according to the present invention fits the compressor impeller to the rotating shaft, and abuts the back member provided on the rotating shaft. The back surface of the compressor impeller is brought into contact with the surface of the compressor impeller, and the front surface of the compressor impeller is brought into contact with the contact surface of a front member provided on the rotating shaft, and the front member has at least a portion thereof fitted with a nut. The front end surface of the compressor impeller is formed into a spherical shape, and the contact surface of the front member that engages with the spherical portion of the front end surface is also formed into a spherical shape with the same curvature. The compressor impeller is positioned relative to the rotating shaft, and the compressor impeller is fastened to the rotating shaft by the nanol portion of the front member.

(Function) In the present invention, the front side end surface of the compressor impeller and the contact surface of the front member that engages with this are both formed in a spherical shape with the same curvature, so that the compressor impeller is positioned with respect to the rotating shaft, and the The compressor impeller is fastened to the rotating shaft by the nut portion of the member.

Therefore, the machining error in the perpendicularity of the nut in the front member is absorbed by the spherical seat, and it is possible to prevent the occurrence of imbalance due to deformation of the shaft or eccentricity of the impeller.

(Example) Hereinafter, the present invention will be explained based on the drawings.

FIG. 1.2 is a diagram showing an embodiment of a fastening structure for a compressor impeller of a turbocharger according to the present invention.

First, the configuration will be explained. FIG. 1 is a sectional view of a portion of a turbocharger including a compressor, and in this figure, 21
22 is a floating metal that rotatably supports the shaft 21, 23 is a thrust collar, 24 is a spacer, 25 is a mechanical seal, and 26 is an impeller.
Among them, the thrust collar 23, spacer 24, and impeller 26 are assembled into the shaft 21 in a fitted manner.

The abutment surface 24B of the impeller 26 example of the spacer 24 (corresponding to the back surface member) is different from the conventional one in that it is not tapered but is formed in a vertical plane perpendicular to the shaft 21. surface) 26B is in contact with it.

On the other hand, an end surface 26A on the front side of the impeller 26 is formed into a concave spherical shape with a constant curvature, and a socket 27 having a convex end surface 27A engages with this end surface 26A and abuts. The nut 27 (corresponding to the front member) is the shaft 21
The end face 27A of the impeller 26 is screwed onto the shaft 21 to fasten the impeller 26 to the shaft 21.
It is formed into a convex spherical shape with the same constant curvature. This curvature is determined by the degree of inclination of the impeller 26 with respect to the shaft 21, and is approximately set to a length slightly larger than the length of the shaft 21 protruding from the impeller 26.

Further, in this example, the curvature is set so that the center of the impeller 26 is aligned with the center of the shaft 21 and a certain gap is provided between the two. That is, in this embodiment, the impeller 26 is centered by the end surface 26A and the nut 27 by the end surface 27A. The reason why there is a gap between the shaft 21 and the impeller 2G is because, as mentioned above, it is difficult to connect the shaft 21 and the impeller 26 with high concentric precision, and also because of thermal expansion caused by the difference in materials between the two. This was done in light of the fact that there are differences in rates, etc.

Next, the effect will be explained.

FIG. 2 is a diagram showing a state in which the impeller 26 and the like are fastened when there is a machining error in the perpendicularity between the core of the threaded portion of the nut 8 and the end surface of the nut 8. Components other than nut 8 are given the same numbers as in FIG. 1.

Now, if there is an angular deviation of θ1 in the perpendicularity of the nut 8, when the nut 8 is fastened, the threaded portion of the shaft 21 will be bent by the angle θ1. This deformation occurs not only in this portion but also in the portion of the shaft 21 that passes through the compressor impeller 26, and the impeller 26 is attached at an angle θ2 with respect to the bearing portion of the shaft 21. For this reason, the impeller 26 is installed tilted and eccentric with respect to the shaft system, resulting in a large imbalance, which causes large vibrations in the turbocharger.

On the other hand, in this embodiment, as shown in FIG. It is structured to be fastened. Therefore, even if the nut 27 has an angle deviation of Oo in its perpendicularity and the nut 27 is fastened,
Any deviation in the perpendicularity of the nut 27 is appropriately absorbed by the spherical seat. As a result, bending of the shaft 21 can be prevented, and eccentricity of the impeller 26 can be prevented. Therefore,
It is possible to prevent the impeller 26 from becoming unbalanced, thereby preventing vibrations of the turbocharger.

FIG. 3 is a diagram showing another embodiment of the present invention, in which the nut 30 is not provided with a spherical seat, but a spacer 31 with a spherical seat is provided between the nut 30 and the impeller 26. It is something. That is, an end surface 31A of the spacer 31 on the impeller 26 side is formed into a spherical shape, and the end surface 26A of the impeller 26 is in contact with this spherical surface. On the other hand, the end surface of the nut 30 is formed in a vertical plane perpendicular to the shaft 21. These nuts 3o and spacers 31 constitute a front member 32.

When the nut 8 is provided with a spherical seat as in the above embodiment, when the center of the spherical surface and the axis of the threaded portion of the nut 8 do not match due to machining accuracy, the spherical seat alone cannot absorb this, and the shaft 21 bends. may occur.

In contrast, in this embodiment, the deviation in the perpendicularity of the nut 3o is appropriately absorbed by the spacer 31 being inclined on its spherical surface 31A in accordance with the inclination of the nut 3°.

Therefore, it is possible to effectively prevent the occurrence of bending due to a misalignment between the center of the spherical surface and the axis of the threaded portion of the nut 30, and prevent the occurrence of a large unbalance of the impeller 26. vibration can be prevented.

(Effects) According to the present invention, it is possible to prevent the occurrence of imbalance due to shaft deformation and impeller eccentricity, and vibration of the turbocharger can be prevented.

[Brief explanation of the drawing]

1. Fig. 1.2 is a diagram showing an embodiment of a fastening structure for a compressor impeller of a turbocharger according to the present invention, Fig. 1 is a cross-sectional view of a portion of the turbocharger including the compressor, and Fig. 2 3 is a diagram showing a fastening situation of an impeller, etc. when there is a machining error in the perpendicularity between the core of the threaded part of the nut and the end face of the nut, and FIG. 3 shows the fastening structure of a compressor impeller of a turbocharger according to the present invention. FIG. 4 is a sectional view of a part of the turbocharger including the compressor showing another embodiment; FIG. 4 is a sectional view of the part of the turbocharger including the compressor showing a fastening structure for the compressor impeller of a conventional turbocharger . 21...Shaft (rotating axis), 22...
・Floating metal, 23... Thrust collar, 24... Spacer (back member), 24B...
... Contact surface, 25 ... Mechanical seal, 26 ... Compressor impeller, 26A ... Front end surface, 2 26B ... Back side, 27...Nut (front member) 27A...End face, 30...Nut, 31...Spacer, 31A...End face, 32... ...Front member.

Claims (1)

[Claims] A compressor impeller is fitted to a rotating shaft, the back surface of the compressor impeller is brought into contact with the contact surface of a back member provided on the rotating shaft, and the back surface of the compressor impeller is brought into contact with the contact surface of a back member provided on the rotating shaft. The front surface of the compressor impeller is brought into contact with the contact surface, and the front member includes a nut in at least a part thereof, and the front end surface of the compressor impeller is formed into a spherical shape, and the front surface of the compressor impeller The contact surface of the front member that engages with the spherical portion of the end face is also formed into a spherical shape with the same curvature, and the compressor impeller is positioned with respect to the rotation axis, and the nut portion of the front member allows the compressor impeller to be aligned with the rotation axis. A fastening structure for a compressor impeller of a turbocharger, characterized in that it is fastened to a compressor impeller.