Canned motor having a high-pressure-resistant can
View Patent ↗A pump having a canned motor which has a stator with an internal rotor disposed therein, the stator and the internal rotor being mutually separated fluid-tightly by a can disposed between stator and internal rotor, the stator having stator teeth which extend radially in the direction of the internal rotor and define with appurtenant stator-tooth end faces a receiving space for the internal rotor and the can, the can lying against the stator-tooth end faces, the can having on its surface facing the stator, in stator-tooth gaps which are respectively defined by two mutually adjacent stator teeth, ribs fitted in in a form-locking manner which taper in the radial direction, starting out from a rib root disposed on the can, with regard to a rib thickness defined in the circumferential direction of the can.
1. A pump comprising:
a canned motor having a stator with an internal rotor disposed in the stator,
wherein the stator and the internal rotor are mutually separated, fluid-tightly, by a can formed from a non-metal material which is disposed between the stator and the internal rotor,
wherein the stator has stator teeth which extend radially in the direction of the internal rotor and define with appurtenant stator-tooth end faces a receiving space for the internal rotor and the can,
wherein the can lies against the stator-tooth end faces and has ribs on its surface that face the stator, and are arranged in stator-tooth gaps which are respectively defined by two mutually adjacent stator teeth,
wherein the ribs are fitted in the stator-tooth gaps in a form-locking manner and taper in the radial direction, starting out from a rib root that is disposed on the can, with regard to a thickness of the ribs, said thickness being defined in the circumferential direction of the can,
wherein each stator tooth consists respectively of a stator tooth shank and a stator tooth head having two stator-tooth-head members which respectively protrude beyond the stator tooth shank in both circumferential directions of the can,
wherein rib flanks formed by side lines of the ribs are respectively in contact, over the region of the height of the ribs, with a contour of the stator-tooth-head members which are shaped complementarily to the side lines, as bearing points fixed against shearing-off,
wherein the stator-tooth contour and thus the height of the ribs is so designed that equivalent stresses in the can are always smaller than the breaking point of the can material in the total region of the can under operating pressure load;
wherein a cross-sectional profile of the ribs has at least one trapezoidal portion with a base line and a roof line, wherein the base line lying against the can and extending in the circumferential direction of the can, and the roof line is disposed in the stator-tooth gap;
wherein the cross-sectional profile of the trapezoidal portion is further determined by the two side lines extending mutually symmetrically and substantially straight, wherein the side lines extend respectively at an angle in the range of 5° to 60° with regard to the radius of the can; and
wherein the side lines pass from the rib into the can in a rounded manner, wherein a first transition between the outer can surface and one of the side lines follows at least one radius from the range of 0.8 to 10 times the wall thickness of the can.
2. The pump according to claim 1 , wherein the height of the ribs starting out from the rib root is greater than the wall thickness of the can.
3. The pump according to claim 2 , wherein:
the can has a wall thickness of 0.1 mm to 2 mm, or
the ribs have a height corresponding to 1 to 10 times the wall thickness of the can.
4. The pump according to claim 1 , wherein
the base line lying against the can and extending in the circumferential direction of the can has a first length of 4.5 to 10 times the wall thickness of the can, and
the roof line disposed in the stator-tooth gap has a shorter second length of 0.5 to 6 times the wall thickness of the can.
5. The pump according to claim 1 , wherein the at least one cross-sectional profile of the ribs further has at least one rectangular portion with a second base line and a second roof line.
6. The pump according to claim 5 , wherein the second base line lies on the first roof line and is shorter such that the rectangular portion forms with the trapezoidal portion a step at the end of each side line.
7. The pump according to claim 6 , wherein the side lines respectively pass from one of the side lines into the roof line in a rounded manner.
8. The pump according to claim 7 , wherein a second transition between one of the side lines and the first roof line follows a radius from the range of 0.8 to 10 times the wall thickness of the can.
9. The pump according to claim 5 , wherein the second base line and second roof line extending in the circumferential direction of the can respectively have a length of 0.4 to 8 times the wall thickness of the can.
10. The pump according to claim 1 , wherein the can is made of a pressure-resistant and high-temperature-resistant material having low electrical conductance, less than 10E−10 S/m.
11. The pump according to claim 10 , wherein the can is made of a plastic.
12. The pump according to claim 11 , wherein the plastic is fiber reinforced.
13. The pump according to claim 11 , wherein the plastic is fiber reinforced and has an index of expansion, in a temperature range of 40° C. to 120° C., similar to that of the material of the stator.
14. The pump according to claim 1 , wherein the can is configured as a single part separate from the pump.
15. The pump according to claim 1 , wherein the can is closed at one end fluid-tightly in a material-locking manner, to form a can-pot.