JP2002047944A - High speed rotation type impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high speed rotation type impeller capable of reducing centrifugal stress generated when rotating at a high speed and improving service life against fatigue when rotating at a high speed. SOLUTION: This high speed rotation type impeller 11 is applied to a compressor of a turbo charger and has a disk 13 having curved front face 12 and a plurality of blades 14 arranged in the disk. A rear surface 17 of the disk 13 is formed into such shape that has a difference in level in which the thickness of its outer peripheral side end part becomes the smallest, and a part on an outer peripheral side in the rear surface 17 is cut to correct balance of the impeller 11. Since a thickness of the disk on the inside in the radial direction is thicker than the outer peripheral side end part, centrifugal stress generated in the part is reduced. Moreover, since the part on the outer peripheral side in the rear surface 17 is cut to correct balance, centrifugal stress in the correction part is not increased while rotating at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller used for a compressor of a turbocharger for an internal combustion engine, and more particularly, to a high-speed impeller suitable for high-speed rotation.

[0002]

2. Description of the Related Art As a conventional impeller, there is known an impeller shown in FIG.
9-2923). The impeller 50 has a substantially conical disk 52 having a curved front surface 51 for guiding air.
And a plurality of blades 53 arranged on the front surface 51 of the disk 52 at equal intervals in the circumferential direction. The front surface 51 is formed into a curved surface in which the distance from the axis of the disk 52 gradually increases from the air inlet side to the air outlet side.
In the vicinity of the outer peripheral end of the front surface 51 of the disk 52,
A plane portion 54 substantially perpendicular to the axis is formed. And
The entire back surface 55 of the disk 52 is formed in a plane substantially perpendicular to the axis. A concave portion 56 is formed at a radially intermediate portion of the rear surface 55 to correct the balance of the impeller 50.

FIG. 6 shows another conventional example of an impeller.
The following are known. In describing the impeller 50 ′, the same parts as those of the above-described conventional impeller 50 shown in FIG. 5A are denoted by the same reference numerals, and redundant description will be omitted. The back surface 55 'of the impeller 50'
So as to form an outer peripheral end portion having a predetermined thickness a between
A flat portion 57 extending radially inward from the outer circumferential surface of the outer circumferential end portion substantially perpendicularly to the axis, and an arc portion 5 continuing to the flat surface portion 57
8.

[0004]

FIG. 5 (a)
In the above impeller 50 (conventional example 1) shown in FIG. 5, a concave portion 56 for correcting the balance is formed at a radially intermediate portion of a back surface 55 formed entirely on a plane substantially perpendicular to the axis.
As shown in FIG. 4B and each graph of FIG.
The centrifugal stress generated in the part is large. In particular, in recent internal combustion engines for vehicles, the engine rotation speed has been increasing, so in order to reduce the size of the impeller and increase the rotation speed to send the same amount of air to the combustion chamber, It is required to reduce the generated stress. On the other hand, in recent years, the traveling distance that guarantees the internal combustion engine has become longer, and it is required to reduce the stress generated in the impeller in order to extend the fatigue life of the impeller. However, in the impeller 50, since the centrifugal stress at the portion A of the concave portion 56 is large, when the impeller 50 is rotated at a high speed, the impeller 50 may be damaged at the portion A, and the fatigue life at the time of high rotation is prolonged. Can not do it.

In the latter impeller 50 '(conventional example 2), as shown in the graphs of FIGS.
The centrifugal stress generated in the portion B near the middle portion of the back surface 55 increases. This is because the thickness of the portion B is thin. Further, in this impeller 50 ', if a part of the flat portion 57 of the back surface 55' (shaded portion in FIG. 6) is cut in order to correct the balance of the impeller, the centrifugal stress generated in the portion B becomes larger. Would. Because of this, impeller 50 '
When the is rotated at a high speed, the impeller 50 'may be damaged at the portion B, and the fatigue life at the time of high rotation cannot be extended.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to reduce the centrifugal stress generated at the time of high rotation, thereby improving the fatigue life at high rotation. Is to provide.

[0007]

The means for solving the above problems and the operation and effects thereof will be described below. In order to solve the above problem, the invention according to claim 1 is applied to a compressor of a turbocharger for an internal combustion engine, and has a substantially conical disk having a curved front surface for guiding a fluid, and a circumferential direction on the front surface of the disk. A high-rotation type impeller having a plurality of blades arranged at equal intervals, wherein the rear surface of the disk has a stepped shape such that the thickness of the outer peripheral end of the disk is the thinnest, Then, a portion on the outer peripheral side in the back surface is cut to correct the balance of the impeller.

According to the present invention, when compared with the prior art example 1 in which the dimensions of the portion other than the rear surface of the impeller are the same, the rear surface of the disk has a step at which the thickness of the outer peripheral end is the thinnest. Because of the shape, when the thickness (disc thickness) of the outer peripheral end of the disk is the same, the thickness of the disk radially inward of the outer peripheral end is greater than that of the first conventional example. As a result, the centrifugal stress generated at the portion A ′ corresponding to the portion A of the impeller 50 of the first conventional example is reduced (see the graph of FIG. 4). Further, in the present invention, the portion on the outer peripheral side in the back surface is shaved to correct the balance of the impeller, so that the centrifugal stress in the balance correcting portion does not increase at high rotation.

Further, when the present invention is compared with the above-mentioned conventional example 2 under the same conditions as the above-mentioned conventional example 1, the rear surface of the disk has a stepped shape such that the thickness of the outer peripheral end is the thinnest. The thickness of the disk radially inward from the outer peripheral end is greater than that of Conventional Example 2 described above. For this reason, the centrifugal stress generated in the portion B ′ corresponding to the portion B of the impeller 50 ′ of the second conventional example is reduced (see FIGS. 3A, 3 B, and 4).
Further, in the present invention, the portion on the outer peripheral side in the back surface is shaved to correct the balance of the impeller, so that the centrifugal stress in the balance correcting portion does not increase at high rotation.

Therefore, according to the present invention, the centrifugal stress generated at high rotation can be reduced, and the fatigue life at high rotation can be improved. According to a second aspect of the present invention, in the high-rotation type impeller according to the first aspect, the back surface of the disk has a first thickness substantially a perpendicular to an axis of the disk forming an outer peripheral end portion having a predetermined thickness a. A flat portion and a second flat portion formed radially inward of the first flat portion and having a predetermined height b with respect to the first flat portion are provided.

According to the present invention, when the disk thickness of the first flat portion is the same as that of the prior arts (1) and (2), the disk thickness of the second flat portion is larger than those of the prior arts. Therefore, the centrifugal stress generated in the second flat portion at the time of high rotation can be reduced.

In the invention according to claim 3, claim 1 or 2
In the high-rotation type impeller described in (1), the first flat portion and the second flat portion on the back surface are continuous via an arc portion having a small radius of curvature.

According to the present invention, since the first and second flat portions are continuous via the arc portion having a small radius of curvature, the centrifugal stress generated at the portion between the two flat portions during high rotation can be reduced. Can be.

According to a fourth aspect of the present invention, in the high-rotation type impeller according to any one of the first to third aspects, an arc portion having a large radius of curvature is provided radially inward of the second flat portion on the back surface. Are provided continuously with the second plane portion.

According to the present invention, the centrifugal stress generated radially inward of the second plane portion of the impeller can be reduced by the arc portion having a large radius of curvature. In the invention according to claim 5, in the high-rotation type impeller according to any one of claims 1 to 4, the predetermined height b corresponds to the outer peripheral side end of the center hole of the disk. It is characterized in that the centrifugal stress generated at the part is set to a value within the tolerance of the endurance target.

According to the present invention, the center hole of the disc is
The centrifugal stress generated at the portion corresponding to the outer peripheral end can be suppressed to a value within the allowable value of the durability target.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high-rotation type impeller according to the present invention will be described below with reference to FIGS. 2A and 2B are enlarged views of a portion D in FIG.

High-speed impeller 11 according to this embodiment
Is used for a compressor of a turbocharger for an internal combustion engine. The high-rotation type impeller 11 (hereinafter, simply referred to as an impeller) is disposed on a substantially conical disk 13 having a curved front surface 12 for guiding air, and at equal intervals in the circumferential direction on the front surface 12 of the disk 13. Multiple blades 14
Consists of

As shown in FIGS. 1 and 2A, a flat portion 16 substantially perpendicular to the axis 15 of the disk 13 is formed at the outer peripheral end of the front surface 12 of the disk 13. The back surface 17 of the disk 13 has a stepped shape such that the outer peripheral end of the disk 13 has the smallest thickness.

Specifically, the back surface 17 of the disk 13
An outer peripheral end having a predetermined thickness a is formed between the outer peripheral surface 18 of the disk 13 and the first planar portion 19 extending radially inward from the outer peripheral surface 18 of the disk 13 substantially perpendicular to the axis 15 of the disk 13; ,
The first flat portion 1 is located radially inward of the first flat portion 19 and
9 and a second flat portion 20 protruding with a step of a predetermined height b. The second plane portion 20 is provided with a first
Like the plane portion 19, it extends substantially perpendicular to the axis 15.

The first flat portion 19 and the second flat portion 2 of the back surface 17
0 is continuous through the arc portion 21 having a small radius of curvature. An arc portion 22 having a large radius of curvature is formed radially inward of the back surface 17 from the second flat portion 20 so as to be continuous with the second flat portion 20.

A third flat portion 23 extending substantially perpendicular to the axis 15 is formed radially inward of the arc portion 22 so as to be continuous with the arc portion 22. The other end of the rotating shaft whose one end is attached to a turbine wheel (not shown) is attached to the center hole 24 of the disk 13.

The outer peripheral portion of the front surface 12 of the disk 13, that is, the portion on the larger diameter side of the disk 13 is cut to correct the balance of the high-rotation type impeller 11. Specifically, as shown by the hatched portion 31 in FIG. 2A, it is most preferable to cut the first flat portion 19 of the back surface 17 to correct the balance. Alternatively, as shown by a hatched portion 32 in FIG. 2B, the second flat portion 20 of the back surface 17 may be cut for balance correction.

The thickness a of the outer peripheral end of the disk 13
Is greater than a predetermined height b. This height b is
The centrifugal stress generated in the portion C corresponding to the outer peripheral end of the center hole 24 of No. 3 is set to a value within the allowable value E of the durability target shown in the graph of FIG.

The radial length L1 of the first flat portion 19 and the radial length L2 of the second flat portion 20 are each approximately 0.1 to 0.1 mm of the outer diameter d of the outer peripheral end of the disk 13. It is set to twice the value.

According to the high-rotation type impeller 11 according to the embodiment described above, the following operational effects can be obtained. (1) Compared with the above-described conventional example 1 by making the dimensions of the portion other than the back surface 17 of the impeller 11 the same, the thickness of the back surface 17 of the disk 13 at the outer peripheral end thereof (the disk thickness with the first flat portion 19) Of the second flat portion 20 radially inward of the first flat portion 19 when the outer peripheral end of the disk 13 has the same thickness. Is thicker than the disk thickness of the portion A in the conventional example 1. As a result, the centrifugal stress generated at the portion A ′ corresponding to the portion A of the impeller 50 of the first conventional example is reduced (see the graph of FIG. 4). 2 (a).
As shown by 1, the first flat portion 19 of the back surface 17 is shaved to correct the balance, or the second flat portion 20 of the back surface 17 is shaved as shown by a hatched portion 32 in FIG. Centrifugal stress in the balance correction section does not increase at high rotation.

Further, when this embodiment is compared with the above-mentioned conventional example 2 under the same conditions as the above-mentioned conventional example 1, the back 1
7 has a stepped shape such that the thickness of the outer peripheral end portion (the thickness of the disk with the first flat portion 19) is the smallest, so that the second flat portion 20 radially inward from the outer peripheral end portion is formed. Is thicker than the disk thickness of the portion B in the conventional example 2. For this reason, the centrifugal stress generated at the portion B ′ corresponding to the portion B of the impeller 50 ′ of the conventional example 2 is reduced (FIG. 3).
(See (a), (b) and FIG. 4). Further, in the present embodiment, a portion on the outer peripheral side (a portion on a larger diameter side) in the back surface 17, for example, a hatched portion 31 in FIG.
Since the hatched portion 32 shown in FIG. 3B is shaved to correct the balance of the impeller 11, the centrifugal stress in the balance correcting portion does not increase during high rotation.

Therefore, the centrifugal stress generated at the time of high rotation can be reduced, and the impeller 11 at the time of high rotation can be reduced.
Can be prevented from being damaged. Thereby, the fatigue life at the time of high rotation can be improved.

(2) When the disk thickness a of the first flat portion 19 is the same as that of the above-mentioned conventional examples (1) and (2), the disk thickness of the second flat portion 20 is the same as that of the two conventional examples. Since the thickness becomes larger by the height b than the disk thickness, the centrifugal stress generated in the second plane portion 20 at the time of high rotation can be reduced.

(3) Since the first and second flat portions 19 and 20 are continuous via the arc portion 21 having a small radius of curvature, centrifugal stress generated at a portion between the two flat portions 19 and 20 during high rotation. Can be alleviated.

(4) The centrifugal stress generated radially inward of the second flat portion 20 of the impeller 11, particularly the centrifugal stress generated at the portion C of the center hole 24 corresponding to the outer peripheral end of the disk 13, is determined by the radius of curvature. This can be mitigated by the large arc portion 22.

(5) The predetermined height b is such that the centrifugal stress generated at the portion C corresponding to the outer peripheral end of the center hole 24 of the disk 13 is within the allowable value E of the durability target shown in the graph of FIG. Therefore, the centrifugal stress generated at the portion corresponding to the outer peripheral end of the center hole 24 of the disk 13 can be suppressed to a value within the allowable value E of the durability target shown in FIG.

(6) The hatched portions 31 in FIGS. 2 (a) and 2 (b)
When shaving the portion indicated by 32 for balance correction, FIG.
A cutter having the same shape as the cutter used for processing the concave portion for correcting the balance in the conventional example 1 shown in FIG. For this reason,
It is possible to cope without a major remodeling of the production line, which requires less capital investment and avoids an increase in production cost.

Although the embodiment of the present invention has been described above, this embodiment can be implemented by changing its configuration as described below. In the above embodiment, the high-rotation type impeller 11 is
Although used for a compressor of a turbocharger for an internal combustion engine, the high-rotation type impeller 11 can be applied to a centrifugal compressor other than the compressor of the turbocharger.

In the above embodiment, the high-rotation type impeller 1
1 has a shape having a first flat portion 19 and a second flat portion 20 having a step of height b.
May be a shape having three or more flat portions that are continuous with a step in a stepwise manner.

In the above embodiment, the rear surface 17
Instead of providing the arc portion 22 and the third flat portion 23, the second flat portion 20 substantially perpendicular to the axis 15 may be extended to the center.

[Brief description of the drawings]

FIG. 1 is a sectional view of a high-rotation type impeller according to an embodiment, with a lower half thereof omitted;

FIGS. 2 (a) and 2 (b) are enlarged views of a portion D in FIG. 1, and are explanatory diagrams showing positions where a balance correcting section is provided.

3 (a) is a schematic configuration diagram showing the impeller of FIG. 1 and the impeller shown in FIG. 6 together, and FIG. 3 (b) is a graph showing simplified centrifugal stress of each part of both impellers.

FIG. 4 is a graph showing experimental results of centrifugal stress generated in each part of the impeller of FIG. 1 and each part of the conventional example shown in FIGS. 5 and 6;

FIG. 5A is a schematic configuration diagram showing a conventional impeller,
(B) is a graph showing a simplified centrifugal stress generated in each part of the impeller.

FIG. 6 is a schematic configuration diagram showing another conventional impeller.

FIG. 7 is a graph showing fatigue life.

[Explanation of symbols]

11 high-rotation type impeller, 12 front, 13 disk, 14 blade, 15 axis, 17 back, 19 first
Plane part, 20... Second plane part, 21, 22... Arc part, 24
... Center hole.

Claims (5)

[Claims] The present invention is applied to a compressor of a turbocharger for an internal combustion engine, and includes a substantially conical disk having a curved front surface for guiding a fluid, and a plurality of disks arranged at regular intervals in a circumferential direction on the front surface of the disk. A high-rotation impeller having blades, wherein the rear surface of the disk has a stepped shape such that the thickness of the outer peripheral end of the disk is the thinnest, and an outer peripheral portion in the rear surface. A high-speed impeller characterized by shaving the wheel to correct the balance of the impeller. 2. A rear surface of the disk, a first flat portion substantially perpendicular to an axis of the disk forming an outer peripheral end portion having a predetermined thickness a, and a radially inner side of the first flat portion, 2. The high-rotation impeller according to claim 1, further comprising a second flat portion formed to have a step of a predetermined height b with respect to the first flat portion. 3. 3. The high-rotation type impeller according to claim 1, wherein the first flat portion and the second flat portion on the back surface are continuous via an arc portion having a small radius of curvature. 4. An arcuate portion having a large radius of curvature is provided radially inward of the second flat portion on the back surface and is continuous with the second flat portion. The high-speed impeller described. 5. The predetermined height b is such that a centrifugal stress generated in a portion corresponding to the outer peripheral end of the center hole of the disk is set to a value within an allowable value of a durability target. The high-rotation type impeller according to any one of claims 1 to 4.