Impeller, in particular for a side channel machine

Abstract

The invention relates to an impeller (1), in particular for a side channel machine, comprising blades (5) arranged distributed in the circumferential direction and formed in each case by a blade wall (6), which blades form open blade chambers (4) in a plan view onto the impeller (1), wherein a blade wall (6) in the plan view starts at a first radius dimension (r.sub.1) related to the geometrical impeller rotation axis (x), which first radius dimension (r.sub.1) corresponds to half or more than half of a second radius dimension (r.sub.2), which second radius dimension (r.sub.2) defines a circumferential rim edge (9) of the impeller (1), and wherein the radius dimension (r.sub.1) defines a radially inner boundary wall (7) of the blade chamber (4), wherein furthermore a blade wall (6) comprises an exposed upper terminating edge, which runs correspondingly radially on the inside into the inner boundary wall (7) and ends radially on the outside in plan view, wherein an imaginary connecting line (V) can be drawn between a run-in point of the terminating edge (12) into the inner boundary wall (7) and a radially outer end of the terminating edge (12) and the terminating edge runs normal to the connecting line (V) with a different offset dimension, wherein a greatest offset dimension results. For the advantageous development, in particular with regard to improved efficiency, it is proposed that the greatest offset dimension corresponds to 0.1 times or more the difference between the second (r.sub.2) and the first radius dimension (r.sub.1).

Claims

1. An impeller comprising blades arranged distributed in the circumferential direction and formed in each case by a blade wall, wherein each blade forms an open blade chamber in a plan view onto the impeller, in which plan view a geometrical impeller rotation axis is depicted in a point-like manner, wherein the blade wall in the plan view starts at a first radius dimension related to the geometrical impeller rotation axis, which first radius dimension corresponds to half or more than half of a second radius dimension, which second radius dimension defines a circumferential rim edge of the impeller, and wherein the first radius dimension defines a radially inner boundary wall of the blade chamber, wherein furthermore a blade wall comprises an exposed upper terminating edge, which runs correspondingly radially on the inside into the inner boundary wall and ends radially on the outside in plan view, wherein an imaginary connecting line can be drawn between a run-in point of the terminating edge into the inner boundary wall and a radially outer end of the terminating edge and the terminating edge runs normal to the connecting line with a different offset dimension, wherein a greatest result of the different offset dimension corresponds to 0.1 times or more the difference between the second and the first radius dimension.

2. The impeller according to claim 1, wherein the greatest result of the different offset dimension corresponds to 0.1 up to 0.6 times the difference between the first and second radius dimension.

3. The impeller according to claim 1, wherein the terminating edge of the blade wall extends radially on the inside in the direction of the impeller rotation axis and defines the size of second radius dimension.

4. The impeller according to claim 1, wherein the blade wall transforms radially at the outside into a circumferential terminating wall and wherein an outer edge of terminating wall defines the second radius.

5. The impeller according to claim 1, wherein the connecting line runs in the extension in the direction of the geometrical impeller rotation axis with a perpendicular spacing dimension with respect to the geometrical impeller rotation axis.

6. The impeller according to claim 5, wherein the perpendicular spatial dimension of the connecting line with respect to the geometrical impeller rotation axis lies in the range from 40% to +40% of the radius dimension.

7. The impeller according to claim 1, wherein the radially outer end of the terminating edge, optionally a tangent passing through the point of intersection of the terminating edge and the terminating wall, forms with the connecting line an acute angle of up to 90.

8. The impeller according to claim 1, wherein the terminating edge at least partially comprises straight segments.

9. The impeller according to claim 1, wherein the terminating edge runs continuously curved between the first and the second radius dimension.

10. The impeller according to claim 1, wherein the terminating edge essentially follows a radius line.

11. The impeller according to claim 10, wherein a radius of the terminating edge is measured from a circle center-point, which lies in the blade chamber following in the circumferential direction.

12. The impeller according to claim 1, wherein the blade wall is enlarged with regard to a wall thickness proceeding from the terminating edge in the direction of the geometrical impeller rotation axis.

13. The impeller according to claim 12, wherein the increase in the wall thickness is different relative to the circumferential direction.

14. The impeller according to claim 1, wherein, relative to a cross-section through the blade wall between the inner run-in point and the outer end, for example in a midpoint between the first radius dimension and the second radius dimension, the blade wall edges form different acute angles with a straight line running parallel to the geometrical impeller rotation axis.

15. The impeller according to claim 14, wherein an acute angle of the blade wall edge is greater against the direction of rotation than an acute angle of the blade wall edge in the direction of rotation.

16. The impeller according to claim 1, wherein the blade wall runs in a convex manner in the direction of rotation.

17. The impeller according to claim 1, wherein a chamber floor of the blade chamber runs in a circular or elliptical form in a cross-section in the connecting line or parallel thereto, wherein the circular or elliptical line runs at any rate radially on the inside into an upper edge of the inner terminating wall.

18. The impeller according to claim 1, wherein a greatest depth of a chamber floor corresponds to 0.25 to 0.75 times the radius difference.

Description

(1) The invention is explained below with the aid of the appended drawing, which however solely represents examples of embodiment. A part which is explained only in relation to one of the examples of embodiment and in a further example of embodiment is not (directly) replaced by another part on account of the particular feature highlighted there is therefore also described for this further example of embodiment as a part that may in any case be present:

(2) FIG. 1 shows an impeller in plan view;

(3) FIG. 2 shows the cross-section according to line II-II in FIG. 1;

(4) FIG. 3 shows the view of the impeller from beneath;

(5) FIG. 4 shows the detail enlargement of region IV in FIG. 1, relating to a first embodiment of a blade wall;

(6) FIG. 5 shows a representation corresponding to FIG. 4, relating to an alternative embodiment of the blade wall;

(7) FIG. 6 shows the cross-section according to line VI-VI in FIG. 3;

(8) FIG. 7 shows the cross-section according to line VII-VII in FIG. 6;

(9) FIG. 8 shows a cross-sectional representation according to FIG. 7, but relating to a further embodiment of the blade wall;

(10) FIG. 9 shows a representation corresponding to FIG. 6 relating to a further embodiment;

(11) FIG. 10 shows a further representation corresponding to FIG. 6 in a further embodiment.

(12) With regard to FIG. 1, an impeller 1, in particular a side channel machine, such as a side channel compressor or a side channel vacuum pump, is first represented and described.

(13) Impeller 1 comprises a hub 2 lying in the centre with a through-hole 3, which serves to fix impeller 1 to a drive shaft (not represented) of a side channel machine.

(14) Impeller 1 comprises, distributed uniformly in the circumferential direction, blade chambers 4 open towards an upper opening plane E with reference to FIG. 2. Said blade chambers, viewed in the circumferential direction, are laterally bordered by blade walls 6 forming blades 5.

(15) Blades 5 and also blade chambers 4 are formed in a radially outer region of impeller 1. Preferably, and in the example of embodiment, blades 5 form, possibly with the exception of a terminating wall, as explained below, the radially outer boundary of impeller 1.

(16) The embodiments represented in particular in FIGS. 1 to 9 relate to an impeller 1 for constituting a two-stage side channel machine. With reference to a central plane running parallel to opening plane E, which central plane intersects geometrical impeller rotation axis x at right angles, blades 5 are accordingly constituted for the formation of blade chambers 4 on both sides of the central plane.

(17) Blade chambers 4 are limited radially on the inside by inner circumferential boundary wall 7. Related to a cross-section, the latter ends with the formation of a boundary wall edge 8 in opening plane E.

(18) A terminating wall 10 is formed circumferentially along circumferential rim edge 9, preferably also forming the latter. According to FIG. 6 for example, said terminating wall also extends into opening plane E with the formation of a terminating wall edge 11 running in opening plane E.

(19) Inner boundary wall 7 runs along a first, inner radius dimension r.sub.1. This radius dimension r.sub.1 preferably relates to a radial inner edge of boundary wall 7 and, in the represented examples of embodiment, preferably corresponds to two thirds of a radius dimension r.sub.2 of a radially outer edge of terminating wall 10.

(20) Blade walls 6 extend between radially inner boundary wall 7 and radially outer terminating wall 10, said blade walls each running in a convex form viewed in direction of rotation d (viewed from a preceding blade wall onto the following blade wall in the direction of rotation).

(21) Thirty to forty five blades 5 can for example be provided distributed uniformly over the circumference, thus for example thirty five blades 5.

(22) Each blade wall 6 comprises an exposed upper terminating edge 12 which extends in opening plane E. This terminating edge 12 runs radially on the inside into the inner boundary wall, in particular into boundary wall edge 8, and ends radially on the outside in circumferential rim edge 9, in particular in terminating wall edge 11 of terminating wall 10.

(23) An imaginary connecting line V can be drawn between the radially inner run-in point of blade wall 6 into boundary wall 7 and the radially outer end of blade wall 6, for example the end of blade wall 6 running into terminating wall 10 (see for example FIG. 4).

(24) Connecting line V runs here in opening plane E or in a plane parallel thereto.

(25) In particular, terminating edge 12 of each blade wall 6 runs normal to connecting line V with a different offset dimension a. Greatest offset dimension a preferably arises midway between radially inner boundary wall 7 and radially outer terminating wall 10 or circumferential rim edge 9.

(26) In the examples of embodiment represented, offset dimension a roughly corresponds to a third of difference dimension c between second radius dimension r.sub.2 and first radius dimension r.sub.1.

(27) Blade walls 6 of the embodiment represented in FIGS. 1 to 4 are constituted such that terminating edges 12 essentially follow a radius line. Radius r.sub.3related to the inner rim edge of the terminating rim edge facing the radius centre-pointis measured from circle centre-point P, which lies in a blade chamber 4 located upstream in direction of rotation d or in blade wall 6 separating preceding blade chamber 4 from described blade chamber 4.

(28) Furthermore, with reference in particular to the rim edge of terminating edge 12 facing circle centre-point P in the horizontal section according to FIG. 4, the ends of terminating edge 12 preferably run tangentially into facing boundary wall 7 or terminating wall 10. For this purpose, the end sections of terminating edge 12 can be provided with a changed radius with respect to radius r.sub.3, in particular with a smaller radius with respect to the latter, the circle centre-point whereof lies in blade chamber 4 bordered by described blade wall 6.

(29) Circle centre-point P of radius r.sub.3 can lie on radius line r.sub.4 bisecting blade chamber 4 in the radial direction between boundary wall 7 and terminating wall 10.

(30) In one embodiment, circle centre-point P is offset radially outwards in the radial direction towards geometrical impeller rotation axis x by dimension z with respect to radius r.sub.4. Dimension z roughly corresponds to a tenth up to a fifth of difference dimension c.

(31) Blade wall 6, in particular terminating edge 12, can also at least partially comprise straight segments 13, which in the horizontal section according to FIG. 5 each assume different acute angles with respect to a radial line. Straight segments 13 are disposed as a whole such that an overall convex course arises as viewed in direction of rotation d of impeller 1.

(32) At each end, a terminating edge 12 thus constituted can run with a radius line tangentially into boundary wall 7 and into circumferential rim edge 9 or into terminating wall 10.

(33) The radially outer end of terminating edge 12, optionally a tangent T passing through the point of intersection of terminating edge 12 and terminating wall 10, can preferably form with connecting line V an acute angle of approx. 70 (see FIG. 4). The radially outer end of terminating edge 12, in a planar embodiment of terminating edge 12, as is preferably and also given for the examples of embodiment, is given by a curvature rim line of terminating edge 12.

(34) Connecting line V runs in the extension in the direction of geometrical impeller rotation axis x with a spacing b (see for example FIG. 1) with respect to geometrical impeller rotation axis x, which perpendicular spacing dimension b roughly corresponds to a twentieth up to a fifteenth of outer radius r2.

(35) Chamber floor 14 arising between two blade walls 6 arranged one behind the other viewed in direction of rotation a and inner boundary wall 7 and, in an embodiment, also radially outer terminating wall 10, runs in the form of a circle segment in a cross-section, in which cross-section impeller rotation axis x is represented as a line (see FIG. 6). The circle centre-point of the circular line describing chamber floor 14 preferably lies within opening plane E.

(36) The circular line describing chamber floor 14 runs in particular radially on the inside into boundary rim edge 8.

(37) In an embodiment with blade chambers 4 closed radially on the outside according to the representations in FIGS. 1 to 9, this circular line also runs preferably radially outwards into terminating rim edge 11 extending in opening plane E.

(38) Alternatively, chamber floor 14 according to the representation in FIG. 9 can also be constituted in the form of a half rectangle with rounded corners 15. Chamber floor 14 is preferably constituted here running parallel to opening plane E. Wall sections extend from the regions of rounded corners 15 facing away from chamber floor 14 into opening plane E, which wall sections run parallel to impeller rotation axis x or form an acute angle therewith.

(39) Greatest depth u of a blade chamber 4 viewed in the direction of impeller rotation axis xmeasured proceeding from opening plane Ecan correspond to 0.5 times difference dimension c between second radius dimension r.sub.2 and first radius dimension r.sub.1.

(40) With reference to a cross-section through blade wall 6 according to the representation in FIG. 7, it can be seen that blade wall 6 is enlarged with regard to wall thickness w proceeding from opening plane E and therefore from terminating edge 12 proceeding in the direction of chamber floor 14. Thus, in the transition to chamber floor 14, a wall thickness w is indicated which roughly corresponds to 3 times thickness w in the region of terminating edge 12.

(41) With respect to a straight line passing centrally through terminating edge 12 in cross-section and running parallel to impeller rotation axis x, blade wall edges 16, especially in the region of radius line r.sub.4, form equal acute angles with respect to the straight line.

(42) FIG. 8 shows an alternative embodiment.

(43) Here, related to a cross-section through blade wall 6 between the inner run-in point and the outer end, for example the midpoint between first radius dimension r.sub.1 and second radius dimension r.sub.2, blade wall edges 16 form different acute angles with respect to the straight line. Thus, blade wall edge 16 pointing against direction of rotation d forms an acute angle .sub.1 of for example 15 to 30, in particular approx. 20 with respect to the straight line, whilst blade wall edge 16 pointing in direction of rotation d forms an acute angle .sub.2 with respect to the straight line of for example 2 to 5.

(44) According to the representation in FIG. 10, blade chambers 4 can also be constituted open radially outwards. Blade wall 6 ending radially exposed at the outside extends radially on the outside in the direction of impeller rotation axis d and defines the size of second radius dimension r.sub.2.

(45) The above comments serve to explain the inventions covered as a whole by the application, said inventions each independently developing the prior art at least by the following combinations of features, namely:

(46) An impeller, which is characterised in that greatest offset dimension z corresponds to 0.1 times or more the difference between second r.sub.2 and first radius dimension r.sub.1.

(47) An impeller, which is characterised in that the greatest offset dimension corresponds to 0.1 to 0.6 times difference c between second r.sub.2 and first radius dimension r.sub.1.

(48) An impeller, which is characterised in that terminating edge 12 of a blade wall 6 also extends radially on the outside in the direction of impeller rotation axis x and defines the size of second radius dimension r.sub.2.

(49) An impeller, which is characterised in that blade wall 6 transforms radially on the outside into a circumferential terminating wall 10 and that an outer edge of terminating wall 10 defines second radius r.sub.2.

(50) An impeller, which is characterised in that connecting line V in the extension in the direction of geometrical impeller rotation axis x runs with a perpendicular spacing dimension b with respect to geometrical impeller rotation axis x.

(51) An impeller, which is characterised in that perpendicular spacing dimension b of connecting line V with respect to geometrical impeller rotation axis x lies in the range from 40% to +40 of outer radius dimension r.sub.2.

(52) An impeller, which is characterised in that the radially outer end of terminating edge 12, optionally a tangent T passing through the point of intersection of terminating edge 12 and terminating wall 10, forms with connecting line V an acute angle of up to 90.

(53) An impeller, which is characterised in that terminating edge 12 at least partially comprises straight segments 13.

(54) An impeller, which is characterised in that terminating edge 12 runs continuously curved between the first r.sub.1 and second radius dimension r.sub.2.

(55) An impeller, which is characterised in that terminating edge 12 essentially follows a radius line.

(56) An impeller, which is characterised in that a radius r.sub.3 of terminating edge 12 is measured from a circle centre-point P, which lies in a blade chamber 4 following in the circumferential direction.

(57) An impeller, which is characterised in that blade wall 6 is enlarged with respect to a wall thickness w proceeding from terminating edge 12 in the direction of geometrical impeller rotation axis x.

(58) An impeller, which is characterised in that the increase in wall thickness w is different related to the circumferential direction.

(59) An impeller, which is characterised in that, related to a cross-section through blade wall 6 between the inner run-in point and the outer end, for example in a midpoint between first radius dimension r.sub.1 and second radius dimension r.sub.2, blade wall edges 16 form different acute angles with respect to a straight line running parallel to geometrical impeller rotation axis x.

(60) An impeller, characterised in that acute angle .sub.1 of blade wall edge 16 is greater against the direction of rotation than acute angle .sub.2 of blade wall edge 16 in the direction of rotation.

(61) An impeller, characterised in that a blade floor 6 runs in a convex manner in direction of rotation d.

(62) An impeller, characterised in that a chamber floor 14 of a blade chamber 4 runs in a circular or elliptical form in a cross-section in connecting line V or parallel thereto, wherein the circular or elliptical line runs at any rate radially on the inside into an upper edge of inner terminating wall 10.

(63) An impeller, which is characterised in that a greatest depth u of a chamber floor 14 corresponds to 0.25 to 0.75 times radius difference c.

(64) TABLE-US-00001 Reference List 1 Impeller Angle 2 Hub .sub.1 Angle 3 Through-hole .sub.2 Angle 4 Blade chamber a Offset dimension 5 Blade b Spacing 6 Blade wall c Difference dimension 7 Boundary wall d Direction of rotation 8 Boundary wall edge r.sub.1 Radius dimension 9 Circumferential rim edge r.sub.2 Radius dimension 10 Terminating wall r.sub.3 Radius 11 Terminating wall edge r.sub.4 Radius line 12 Terminating edge u Depth 13 Straight segment w Wall thickness 14 Chamber floor x Impeller rotation axis 15 Corner z Dimension 16 Blade wall edge E Opening plane P Circle centre-point T Tangent V Connecting line