Compressor wheel of a charging device

Abstract

A compressor wheel of a charging device may include a hub, a plurality of blades and a wheel back. The wheel back may have an undulating profile which extends from the hub in a radial direction. The undulating profile may include a plurality of regions. The plurality of regions may adjoin one another and may include a first concave region, a second convex region, a third concave region, and a fourth convex region. The second convex region may adjoin the first concave region. The third concave region may adjoin the second convex region. The fourth convex region may adjoin the third concave region.

Claims

1. A compressor wheel of a charging device, comprising: a hub, a plurality of blades and a wheel back, wherein the wheel back has an undulating profile which extends from the hub in a radial direction, the undulating profile including a plurality of regions which emerge from the hub in the radial direction and adjoin one another, wherein the plurality of regions of the undulating profile include: a first concave region; a second convex region adjoining the first concave region; a third concave region adjoining the second convex region; and a fourth convex region adjoining the third concave region; and wherein at least one of the first concave region has a radial extent of approx. 7% of a radius of the compressor wheel, and the fourth convex region has a radial extent of approx. 20% of a radius of the compressor wheel.

2. The compressor wheel according to claim 1, wherein the fourth convex region includes a bulge that has an axial height of approx. 0.15 mm.

3. The compressor wheel according to claim 1, wherein the hub extends from an axis of rotation to the first concave region and the hub includes a flat end surface.

4. The compressor wheel according to claim 3, wherein the flat end surface has a radial extent of approx. 15% of the radius of the compressor wheel.

5. The compressor wheel according to claim 1, wherein the first concave region has a radial extent of approx. 7% of the radius of the compressor wheel.

6. The compressor wheel according to claim 1, wherein the second convex region has the radial extent of approx. 25% of the radius of the compressor wheel, and the fourth convex region has the radial extent of approx. 20% of the radius of the compressor wheel.

7. The compressor wheel according to claim 1, wherein the third concave region has a radial extent of approx. 30% of the radius of the compressor wheel.

8. An exhaust gas turbocharger, comprising: a compressor wheel, the compressor wheel including: a hub; a plurality of blades; and a wheel back, the wheel back having an undulating profile that extends from the hub in a radial direction; the undulating profile including a plurality of regions extending from the hub in the radial direction, wherein the plurality of regions of the undulating profile include a first concave region, a second convex region, a third concave region, and a fourth convex region; wherein the second convex region is disposed between the first concave region and the third concave region, and the third concave region is disposed between the second convex region and the fourth convex region; and wherein at least one of: the first concave region has a radial extent of approx. 7% of a radius of the compressor wheel; the second convex region has a radial extent of approx. 25% of a radius of the compressor wheel; wherein the third concave region has a radial extent of approx. 30% of a radius of the compressor wheel; and wherein the fourth convex region has a radial extent of approx. 20% of a radius of the compressor wheel.

9. The exhaust gas turbocharger according to claim 8, wherein the plurality of regions adjoin one another such that the second convex region adjoins the first concave region, the third concave region adjoins the second convex region, and the fourth convex region adjoins the third concave region.

10. The exhaust gas turbocharger according to claim 8, wherein the fourth convex region includes a bulge that has an axial height of approx. 0.15 mm.

11. The exhaust gas turbocharger according to claim 8, wherein the hub extends from an axis of rotation to the first concave region.

12. The exhaust gas turbocharger according to claim 11, wherein the hub has a flat axial end surface.

13. The exhaust gas turbocharger according to claim 12, wherein the flat axial end surface has a radial extent of approx. 15% of the radius of the compressor wheel.

14. The exhaust gas turbocharger according to claim 8, wherein the first concave region has the radial extent of approx. 7% of the radius of the compressor wheel.

15. The exhaust gas turbocharger according to claim 8, wherein the second convex region has the radial extent of approx. 25% of the radius of the compressor wheel.

16. The exhaust gas turbocharger according to claim 8, wherein the third concave region has the radial extent of approx. 30% of the radius of the compressor wheel.

17. The exhaust gas turbocharger according to claim 8, wherein the fourth convex region has the radial extent of approx. 20% of the radius of the compressor wheel.

18. The exhaust gas turbocharger according to claim 8, wherein the first concave region has the radial extent of approx. 7% of the radius of the compressor wheel, the second convex region has the radial extent of approx. 25% of the radius of the compressor wheel, the third concave region has the radial extent of approx. 30% of the radius of the compressor wheel, and the fourth convex region has the radial extent of approx. 20% of the radius of the compressor wheel.

19. A compressor wheel for a charging device, comprising: a hub, a plurality of blades, and a wheel back; the wheel back having an undulating profile extending from the hub in a radial direction, the undulating profile including a plurality of regions that emerge from the hub in the radial direction and adjoin one another, and wherein the plurality of regions of the undulating profile include: a first concave region; a second convex region adjoining the first concave region; a third concave region adjoining the second convex region; and a fourth convex region adjoining the third concave region, wherein the fourth convex region includes a bulge that has an axial height of approx. 0.15 mm.

20. The compressor wheel according to claim 19, wherein at least one of: the first concave region has a radial extent of approx. 7% of a radius of the compressor wheel; the second convex region has a radial extent of approx. 25% of a radius of the compressor wheel; the third concave region has a radial extent of approx. 30% of a radius of the compressor wheel; and the fourth convex region has a radial extent of approx. 20% of a radius of the compressor wheel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings, in each case schematically:

(2) FIG. 1 shows a sectional illustration through a compressor wheel according to the invention,

(3) FIG. 2 shows a detailed illustration from FIG. 1.

DETAILED DESCRIPTION

(4) According to FIG. 1 and partially to FIG. 2, a compressor wheel 1 according to the invention of a charging device 2 (otherwise merely indicated), in particular of an exhaust gas turbocharger 3, has a hub 4 and blades 5 and a wheel back 6. In order now to be able to reduce a tendency of the compressor wheel 1 to cracking and thereby to be able to extend the service life thereof, it is provided according to the invention that the wheel back 6 has an undulating profile which emerges from the hub 4 in the radial direction 7, with regions 8, 9, 10 and 11 emerging from the hub 4 in the radial direction, 7 and adjoining one another.

(5) As can be clearly seen here in the left half of FIG. 1, the first region 8 is of concave design while the second region 9 which adjoins the latter in the radial direction 7 is of convex design. The third region 10 in turn adjoining the second convex region 9 is of concave design while the fourth region 11 is in turn of convex design. In FIG. 1, the original profile of the wheel back in the case of conventional compressor wheels is denoted by reference sign 12, while reference sign 13 denotes the undulating profile according to the invention.

(6) The first concave region 8 here is rounded with a radius R1 which lies between 3.125% and 6% of the diameter D of the compressor wheel 1, while the second convex region 9 is rounded with a radius R2 which approximately corresponds to the diameter D of the compressor wheel 1. The first concave region 8 begins in the radial direction 7 at P1 and ends at P2. In this case, a radial distance between the points P1 and P2 is aP2=0.77R1.

(7) The third region 10 merges here into the second convex region 9 via a tangent 17 applied at point P2. A radial distance between the points P2 and P3 is aP3=0.225R.sub.2. At the same time, the third region 10 merges into the fourth convex region 11 via a tangent which is applied at the point P4 and is not shown.

(8) A bulge in the fourth convex region 11 has an axial height here of approx. 0.15 mm. The axial height h refers here to the height in the axial direction of the compressor wheel 1. With reference to a diameter of the compressor wheel 1, a bulge radius R4 in the fourth convex region 11 is a quarter of the diameter D of the compressor wheel (R4D/4=R/2). The circle formed by the radius R4 intersects the point P5, which is located at the outer diameter, and at the same time determines the position of the point P4 by a vertical intersection through the central point M of the circle and the undulating profile 13.

(9) All embodiments have in common, that there are no depressions in the wheel back 6 extending in the direction of the blades 5 which are axially deeper than the point P5 on the outside diameter. Thus an outer contour of the wheel back 6 does not intersect at any point a radial line 18 passing through the point P5, but may only be tangent to this line. Thus, no strength-reducing depressions exist.

(10) Looking further at FIG. 1, it can be seen that the hub 4 reaches from an axis of rotation 14 as far as the first region 8 and has a flat annular end surface 15. Said flat end surface 15 has in this case a radial extent of approx. 15% of the radius R of the compressor wheel 1.

(11) The first concave region 8 in turn has a radial extent of approx. 7% of the radius R of the compressor wheel 1, while the second convex region 9 has a radial extent of approx. 25% of the radius R of the compressor wheel 1. Looking at the third concave region 10, it can be seen that the latter has a radial extent of approx. 30% of the radius R of the compressor wheel 1, while the radial extent of the fourth convex region 11 is approx. 20% of the radius R. The radial extents of the end surface 15 and of the individual regions 8 to 11 together produce approx. 97% of the radius R of the compressor wheel 1, since a blade tip 16 still protrudes slightly in the radial direction over the wheel back 6.

(12) Looking at the profile 12 of a wheel back of a compressor wheel known from the prior art with the profile 13 according to the invention of the wheel back 6 of the compressor wheel 1 according to the invention, it can be seen that the wheel back 6 is thickened in particular in the two convex regions 9 and 11 since the stress loading and therefore also the tendency to cracking are at the greatest in said regions. By means of the local thickening of the wheel back 6 in the two convex regions 9, 11, a reinforcement of the wheel back 6 can therefore be obtained exclusively in the required stress-loaded regions and, as a result, a minimizing of the tendency to cracking can be achieved with minimal additional weight. In addition, of course, the hub 4 can also be thickened by approx. 0.9<H<1.2 mm in the region of the end surface 15. The height H of the thickening or of the step in the region of the hub 4 corresponds here to
H0.016D.

(13) The high stress in this area can thus be better absorbed. It is particularly advantageous that a through hole 19 for receiving a shaft extends directly to the end surface 15 without any widening of the through hole. Only a small bevel is provided.

(14) With the undulating profile 13 according to the invention of the wheel back 6, the life expectancy can be increased by 50 to 100% in comparison to previous compressor wheels.