ROTARY ATOMIZER TURBINE

Abstract

A rotary atomizer turbine is provided, the turbine including a turbine wheel with multiple turbine blades, a blade duct containing the turbine blades and being delimited radially by a duct wall, a braking air nozzle, a driving air nozzle and an outlet region at the outlet of the driving air nozzle. The outlet region is delimited at the outside by the duct wall of the blade duct and at the inside by the turbine blade respectively passing through it. The blade duct is delimited radially at the inside opposite the braking air nozzle by a stationary flow barrier. Furthermore, the outlet region of the individual driving air nozzles is a divergent cross-sectional region which widens in the flow direction and rotates with that turbine blade passing the driving air nozzle.

Claims

1.-10. (canceled)

11. A radial turbine for driving a spraying body in a rotary atomizer, the turbine comprising: a turbine wheel rotatably coupled about an axis, the turbine wheel having a plurality of turbine blades extending axially from the turbine wheel, the plurality of turbine blades being annularly arranged on the turbine wheel at a perimeter of the turbine wheel, the arrangement of the plurality of turbine blades defining a driving direction of the turbine wheel about the axis and a braking direction of the turbine wheel counter to the driving direction about the axis; a duct wall radially encircling the turbine wheel and axially extending over the turbine blades and defining a blade duct over the turbine wheel, the blade duct being coaxially arranged with the turbine wheel; at least one driving air nozzle opening into the blade duct and axially overlapping the turbine blades, the at least one driving air nozzle configured to direct a flow of driving air along the driving direction, the at least one driving air nozzle defining an outlet region between a circumference of the blade duct and a portion of the duct wall open to the at least one driving air nozzle; at least one braking air nozzle opening into the blade duct and axially overlapping the turbine blades, the at least one braking air nozzle being configured to direct a flow of braking air to the plurality of turbine blades along the braking direction; and a flow barrier fixed relative to the duct wall within the blade duct, the flow barrier being radially inside of the turbine blades and axially overlapped with the turbine blades, the flow barrier opposing the outlet region of the at least one braking air nozzle, the flow barrier configured to retain braking air within the blade duct.

12. The radial turbine according to claim 11, wherein the flow barrier extends over a circumferential angle of greater than 5° and less than 90°.

13. The radial turbine according to claim 11, wherein the turbine wheel defines an open region radially inside of the turbine blades.

14. The radial turbine according to claim 11, wherein, upon rotation of the turbine blades respectively along the outlet region of the at least one driving air nozzle, each of the turbine blades respectively defines a divergent cross-sectional region between the portion of the duct wall open to the at least one driving air nozzle and a front surface of the respective turbine blade, the divergent cross-sectional regions each maintaining a shape that widens along the flow of driving air while passing the at least one driving air nozzle.

15. The radial turbine according to claim 14, wherein each of the divergent cross-sectional regions angularly widens at least 2° along the flow of driving air.

16. The radial turbine according to claim 11, wherein, in the outlet region of the at least one driving air nozzle, the portion of the duct wall open to the at least one driving air nozzle includes a recess arched radially outwardly and configured to form the divergent cross sections with the turbine blades, respectively.

17. The radial turbine according to claim 16, wherein the recess circumferentially extends over an angle of at least 10° and at most 90°.

18. The radial turbine according to claim 11, wherein each of the turbine blades is curved such that the outer end thereof is directed counter to the driving direction of the turbine wheel.

19. The radial turbine according to claim 18, wherein a front surface at the outer end of each of the turbine blades extends radially inwardly at an angle of at least 2° from the circumference of the blade duct.

20. The radial turbine according to claim 11, wherein the driving air nozzle is a de Laval nozzle.

21. A radial turbine for driving a spraying body in a rotary atomizer, comprising: a turbine wheel having multiple turbine blades annularly distributed over the circumference, the turbine wheel configured to rotates about an axis in a driving direction; a duct wall coaxially encircling the turbine blades to define a blade duct therewithin; at least one braking air nozzle opening into the blade duct, the at least one braking air nozzle configured to direct a flow of braking air counter to the driving direction of the turbine wheel; and at least one driving air nozzle opening into the blade duct, the at least one driving air nozzle configured to direct a flow of driving air along the driving direction of the turbine wheel, the at least one driving air nozzle defining an outlet region between a portion of the duct wall open to the at least one driving air nozzle and a circumference of the blade duct, wherein, upon rotation of the turbine wheel in the driving direction, and while each of the turbine blades respectively passes the at least one driving air nozzle, each of the turbine blades defines a divergent cross-sectional region between the portion of the duct wall open to the at least one driving air nozzle and a front surface of the respective turbine blade, the divergent cross-sectional regions each maintaining a shape that widens along the flow of driving air.

22. The radial turbine according to claim 21, a flow barrier fixed relative to the duct wall within the blade duct, the flow barrier being radially inside of the turbine blades and axially overlapped with the turbine blades, the flow barrier opposing the outlet region of the at least one braking air nozzle, the flow barrier configured to retain braking air within the blade duct.

23. The radial turbine according to claim 22, wherein the flow barrier extends over a circumferential angle of greater than 5° and less than 90°.

24. The radial turbine according to claim 21, wherein the turbine wheel defines an open region radially inside of the turbine blades.

25. The radial turbine according to claim 21, wherein each of the divergent cross-sectional regions angularly widens at least 2° along the flow of driving air.

26. The radial turbine according to claim 21, wherein, in the outlet region of the at least one driving air nozzle, the portion of the duct wall open to the at least one driving air nozzle includes a recess arched radially outwardly and configured to form the divergent cross sections with the turbine blades, respectively.

27. The radial turbine according to claim 26, wherein the recess circumferentially extends over an angle of at least 10° and at most 90°.

28. The radial turbine according to claim 21, wherein each of the turbine blades is curved such that the outer end thereof is directed counter to the driving direction of the turbine wheel.

29. The radial turbine according to claim 28, wherein a front surface at the outer end of each of the turbine blades extends radially inwardly at an angle of at least 2° from the circumference of the blade duct.

30. The radial turbine according to claim 21, wherein the driving air nozzle is a de Laval nozzle.

Description

DRAWINGS

[0035] Other advantageous refinements of the present disclosure are explained in more detail below together with the description of the exemplary implementations of the present disclosure on the basis of the figures, in which:

[0036] FIG. 1 shows a side view of a rotary atomizer turbine,

[0037] FIG. 2 shows an exploded side view of the rotary atomizer turbine from FIG. 1,

[0038] FIGS. 3A-3F are schematic illustrations of the divergent cross-sectional region at the outlet of the driving air nozzles for different, successive angular positions of the turbine wheel,

[0039] FIG. 4 is a detail illustration of the divergent cross-sectional region,

[0040] FIG. 5 shows a cross-sectional view illustrating a flow barrier opposite the braking air nozzle,

[0041] FIG. 6 is a schematic illustration of the disruptive convergent-divergent cross-sectional region in the case of the prior art.

DETAILED DESCRIPTION

[0042] Referring to FIGS. 1-2, a rotary atomizer turbine 1 for driving a bell plate according to the present disclosure is shown, which rotary atomizer turbine 1 may be screwed onto a bell plate shaft 2, wherein the bell plate shaft 2 rotates about an axis of rotation 3 during operation.

[0043] The bell plate shaft 2 bears a turbine wheel 4, i.e., the turbine wheel 4 is mounted to the bell plate shaft 2. Numerous turbine blades 5 are attached to the turbine wheel 4 so as to be distributed over the circumference and project axially from the turbine wheel 4, e.g., the turbine blades 5 are formed on a side of the turbine wheel 4. The turbine wheel 4 presents a circular disk 17 extending to a peripheral rim. The turbine blades 5 extend radially relative to the axis 3 and are spaced annularly about the circular disk 17. The individual turbine blades 5 project in this case into a blade duct 6 (shown in FIGS. 3A-5), which is delimited radially at the outside by an annularly encircling duct wall 7.

[0044] The housing 16 of the rotational atomizer turbine 1 has several housing parts, as shown in FIGS. 1 and 2. The rotary atomizer turbine 1 includes a first end component 25, a nozzle ring 26, a distance ring 27 and a second end component 28. The first and second end components 25, 28, the nozzle ring 26 and the distance ring 27 are axially and radially coupled to one another, e.g., with fastening pins 30, about the bell plate shaft 2 to for a housing assembly for the rotary atomizer turbine 1, such that the bell plate shaft 2 may rotate about the axis 3 when encased in the housing (FIG. 1). The nozzle ring 26 surrounds the turbine wheel 4, as shown in FIG. 5, so that the interior of the nozzle ring 26 forms a cylindrical turbine chamber 25, in which the turbine wheel 4 is rotated.

[0045] Multiple driving air nozzles 8 issue into the blade duct 6 from the outside, as can be seen from FIGS. 3A-3F and 4. The air nozzles 8 are defined in the nozzle ring 26. It should be understood that the nozzle ring 26 may define any suitable number of air nozzles 8. The individual driving air nozzles 8 each discharge a driving air flow substantially tangentially, in the direction of the arrow shown in FIGS. 3A-5, into the blade duct 6 in order to rotate the turbine wheel 4. In this case, at the outlet region of the driving air nozzles 8, the driving air flows initially through a divergent cross-sectional region 9.

[0046] The divergent cross-sectional region 9 is formed at the inside by an arched front side 10 of the turbine blade 5 that is presently passing through and at the outside by an arched recess 11 in the duct wall 7. The divergent cross-sectional region 9 thus rotates in the direction of rotation with that turbine blade 5 which is respectively presently passing the outlet region of the respective driving air nozzle 8.

[0047] By contrast to the known rotary atomizers described in the introduction, however, no convergent-divergent cross-sectional region similar to a de Laval nozzle is formed at the outlet of the individual driving air nozzles 8, because this would lead to high-loss compression shocks. The absence of such a disruptive convergent-divergent cross-sectional region thus advantageously leads to an increase in drive power of the rotary atomizer turbine 1 according to the present disclosure.

[0048] Referring again to FIG. 2, of the pair of pins 30 may extend through openings defined in the first and second end components 25, 28, the nozzle ring 26 and the distance ring 27 to lock these parts together in assembled mode and prevent side movement of the first and second end components 25, 28, the nozzle ring 26 and the distance ring 27 relative to one another.

[0049] The annular intermediate chamber 12 is covered by the distance ring 27, to cover the opening in the mounted state.

[0050] The fixed nozzle itself is a Laval nozzle. This is characterized by a convergent channel which accelerates the flow to sonic speed up to the narrowest cross section. From the narrowest cross-section, the channel is divergent, whereby an acceleration to supersonic speed is carried out. The divergent channel between the housing and the blade is a supersonic nozzle when the flow enters at supersonic speed. This divergent channel between the housing and the rotating blade can also be viewed as an extension of the Laval nozzle.

[0051] Downstream of the individual driving air nozzles 8, the arched recess 11 extends in the circumferential direction in each case over an angle β in the range of 15°-30°. Specifically, as shown in FIG. 4, the driving air nozzles 8 include an edge 32 and an end 33 spaced along the circumference of the duct wall 7, i.e., along an arc of the duct wall 7. The path of the circumference of the duct wall 7 across the air nozzle 8 from the edge 32 to the end 33, i.e., an ideal circumference of the duct wall 7, is identified with reference numeral 12 in FIG. 4. The angle β extends along the path 12 from the edge 32 to the end 33. The angle β shown in FIG. 4 is shown for example, and it should be appreciated that the angle β may be between 15°-30°, as set forth above.

[0052] With continued reference to FIG. 4, the front side 10 of the individual turbine blades 5 encloses in each case, at its outer, free end 33, an angle α=15°-30° with the path 12 of the circumference of the duct wall 7. Specifically, the tangent 34 of the front side 10 of the turbine blade 5 at the free end 33 is shown in FIG. 4. The angle α is defined between the tangent 34 of the front side 10 and the path 12 of the circumference of the duct wall 7, as shown in FIG. 4.

[0053] Referring to FIG. 5, a braking air nozzle 13 opens out into the blade duct 6 in order to subject the turbine blades 5 to a flow of working air, wherein the braking air flow is directed counter to the direction of rotation of the turbine wheel 4.

[0054] In this case, at the inner side of the blade duct 6, there is situated a flow barrier 14 which prevents the braking air from the braking air nozzle 13 from simply flowing in a radial direction through the annularly encircling blade arrangement and then emerging from the blade duct 6 again at the inside. Referring in particular FIG. 2, the flow barrier 14 is fixed to the distance ring 27, and extends axially toward the turbine wheel 4. When assembled, as shown, e.g., in FIG. 1, the flow barrier 14 is radially inward of the turbine blades 5 and the blade duct 6. In this way, the braking air that emerges from the braking air nozzle 13 is retained within the blade duct 6 and thus contributes in a significantly more efficient manner to the braking of the turbine wheel 4.

[0055] The flow barrier 14 may extend in the circumferential direction over an angle of 20°-40°, wherein, in one example, an angle of 33° is preferred.

[0056] Finally, FIG. 6 shows, for comparison, the outlet region of the driving air nozzle 8 in the case of a conventional rotary atomizer turbine. It can be seen from the drawing that, upstream of the divergent cross-sectional region 9, there is initially a convergent cross-sectional region 15. The convergent cross-sectional region 15 thus forms, together with the subsequent divergent cross-sectional region 9, a nozzle similar to a de Laval nozzle, which leads to undesired compression shocks, whereby the drive power of the rotary atomizer turbine is reduced.

[0057] It should be understood that the present disclosure is not restricted to the exemplary description herein. Rather, numerous variants and modifications are possible according to the principles of the present disclosure.