Centrifuge including a frame and a bearing device having a pair of cantilevers and a pair of spring elements located between the cantilevers and the frame
A screw centrifuge including a drum having a rotor, the drum having two axial ends and a horizontal axis of rotation, and a screw arranged in the drum and configured to rotate relative to the drum at a speed different from a rotation speed of the drum. Also included is a bearing device located at each axial end of the drum and configured to bear the drum. Each bearing device includes a housing and a pair of cantilevers extending in opposite directions away from the housing. Further included is a pair of spring elements associated with each bearing device and configured for sprung support of the drum. Each spring is arranged between one of the cantilevers and a frame, the spring elements being located at each axial end of the drum.
1. A screw centrifuge comprising:
a drum including a rotor, the drum having two axial ends and a horizontal axis of rotation;
a screw arranged in the drum and configured to rotate relative to the drum at a speed different from a rotation speed of the drum;
a bearing device located at each axial end of the drum and configured to bear the drum;
each bearing device including a housing and a pair of cantilevers extending in opposite directions away from the housing; and
a pair of spring elements associated with each bearing device and configured for sprung support of the drum and each spring is arranged between one of the cantilevers and a frame, spring elements being located at each axial end of the drum.
2. The screw centrifuge of claim 1 , wherein a ratio between a length of the drum to a diameter of the drum is greater than 2.
3. The screw centrifuge of claim 2 , wherein the spring elements are configured as combined spring and damping elements.
4. The screw centrifuge of claim 3 , wherein a damping of the separate damping elements is a function of a rotation speed such that a high damping level is produced even at low rotation speeds by driving through a rotor natural shape, while a lower damping level is provided at an operating rotation speed above a resonant frequency.
5. The screw centrifuge of claim 1 , wherein the spring elements are configured as combined spring and damping elements.
6. The screw centrifuge of claim 1 , further comprising at least one damping element separate from the pair of spring elements.
7. The screw centrifuge of claim 1 , wherein the spring elements act as compression elements for the sprung support of the drum on the frame in a non-radial direction.
8. The screw centrifuge claim 1 , wherein the spring elements include helical springs, and longitudinal axes of the helical springs are aligned at an angle of 0 to 30° from the vertical.
9. The screw centrifuge of claim 8 , wherein the helical springs are aligned at an angle of 0 to 15° from the vertical.
10. The screw centrifuge of claim 8 , wherein each helical spring is loaded in compression in the vertical direction and is loaded in shear in the axial direction.
11. The screw centrifuge of claim 1 , wherein the spring elements have a tunable spring stiffness in at least two mutually perpendicular directions.
12. The screw centrifuge of claim 1 , wherein the spring elements have a horizontal spring stiffness of 30% to 100% of a vertical spring stiffness when longitudinal axes of the spring elements are aligned vertically in an installed state.
13. The screw centrifuge of claim 1 , wherein the spring elements have a horizontal spring stiffness of 50%-100% of a vertical spring stiffness when longitudinal axes of the spring elements are aligned vertically.
14. The screw centrifuge of claim 1 , further comprising a pair of damping elements which are arranged physically separately from the spring elements and are configured to support the drum.
15. The screw centrifuge of claim 14 , wherein a damping of the separate damping elements is a function of a rotation speed such that a high damping level is produced even at low rotation speeds by driving through a rotor natural shape, while a lower damping level is provided at an operating rotation speed above a resonant frequency.
16. The screw centrifuge of claim 1 , wherein the spring elements are arranged alongside the drum.
17. The screw centrifuge of claim 1 , wherein the two cantilevers are aligned in a common plane.
18. The screw centrifuge of claim 1 , wherein the two cantilevers are aligned at an angle to a horizontal plane of the frame.
19. The screw centrifuge of claim 1 , wherein the two cantilevers are arranged above the axis of rotation of the drum.
20. The screw centrifuge of claim 1 , wherein the bearing devices each have two bearings and the spring elements are arranged on a plane at right angles to the axis of rotation, which axis of rotation is located between the bearings.
21. The screw centrifuge of claim 20 , wherein a center of the spring elements in an axial direction alongside the bearings is located at a height which corresponds to a height of a center of the bearings.
22. The screw centrifuge of claim 20 , wherein one of the two bearings is a grooved ball bearing and the other bearing is a cylindrical roller bearing, and the two bearings are arranged in a respective one of the bearing housings.
23. The screw centrifuge of claim 1 , wherein a distance between the two bearings is at least half of an internal diameter of the bearings.
24. The screw centrifuge of claim 1 , wherein a damping of the spring elements at resonance is at least 3%.
25. The screw centrifuge of claim 1 , wherein a ratio between a length of the drum to a diameter of the drum is greater than 2.5.
26. The screw centrifuge of claim 1 , wherein a ratio between a length of the drum to a diameter of the drum is greater than 3.
27. The screw centrifuge of claim 1 , wherein a damping of the spring elements at resonance is at least between 10% and 30%.