Centrifugal separator having a system for detecting rotation

Patent metadata

Field	Value
Publication number	US-10955432-B2
Application number	US-201615561848-A
Country	US
Kind code	B2
Filing date	Mar 21, 2016
Priority date	Mar 27, 2015
Publication date	Mar 23, 2021
Grant date	Mar 23, 2021

Abstract

A centrifugal separator includes a frame and a drive member configured to rotate a rotating part in relation to the frame around an axis of rotation. The rotating part includes a spindle and a centrifuge rotor enclosing a separation space. The rotating part is supported by the frame by at least one bearing device. The centrifugal separator further includes a system for detecting rotation of the rotating part. The system includes at least one first type of sector each occupying a first length of the perimeter of a member arranged for rotation with the rotating part, and at least one second type of sector each occupying a second length of the perimeter of the member arranged for rotation. The at least one second type of sector is spaced apart from the at least one first type of sector. The second length is different compared to the first length. The at least one first and second types of sectors are irregularly spaced around the perimeter of the member arranged for rotation. The system further includes an inductive sensor arranged to detect the at least one first and second types of sectors and give rise to a binary pulse sequence upon rotation of the member arranged for rotation. The temporal widths of the binary pulses correspond to the lengths of the at least one first and the at least one second types of sectors, respectively.

First claim

The invention claimed is:

1. A centrifugal separator comprising:
a frame;
a drive member configured to rotate a rotating part in relation to the frame around an axis of rotation, wherein the rotating part comprises a spindle and a centrifuge rotor enclosing a separation space, said rotating part being supported by the frame by at least one bearing device; and
a system for detecting rotation of said rotating part, said system comprising:
at least one first type of sector, each at least one first type of sector occupying a first length of a perimeter of a member arranged for rotation with said rotating part and having a distance in a radial direction;
at least one second type of sector, each at least one second type of sector occupying a second length of the perimeter of said member arranged for rotation and having a distance in the radial direction, wherein the at least one second type of sector is spaced apart from said at least one first type of sector, wherein the second length is different compared to said first length, wherein the distance in the radial direction of the at least one first type of sector and the distance in the radial direction of the at least one second type of sector are different than remaining parts of the rotating part, and wherein said at least one first and second types sectors are irregularly spaced around the perimeter of said member arranged for rotation; and
an inductive sensor arranged to detect said at least one first and second types of sectors and give rise to a binary pulse sequence upon rotation of said member arranged for rotation, and wherein the temporal widths of the binary pulses correspond to the lengths of said at least one first and said at least one second types of sectors, respectively.

2. The centrifugal separator according to claim 1 , wherein the system comprises a single inductive sensor.

3. The centrifugal separator according to claim 1 , wherein the member arranged for rotation is a disc arranged around said spindle.

4. The centrifugal separator according to claim 3 , in which the sectors protrude more in the axial direction as compared to the other portions of the disc.

5. The centrifugal separator according to claim 3 , wherein the sectors of the disc have a larger radius compared to the other portions of the disc.

6. The centrifugal separator according to claim 3 , wherein the at least one first type of sector is of the same material as the at least one second type of sector.

7. The centrifugal separator according to claim 3 , wherein the disc comprises a single first type of sector and a single second type of sector.

8. The centrifugal separator according to claim 3 , wherein the spindle is supported by at least one bottom bearing and at least one top bearing, and the top bearing is arranged closer to the centrifuge rotor as compared to the bottom bearing, and
wherein the disc is located at the top bearing and the inductive sensor is located radially outside the disc.

9. The centrifugal separator according to claim 1 , wherein the member arranged for rotation is the spindle.

10. A system for detecting rotation of a rotating axis, said system comprising:
a disc arranged to rotate with said rotating axis, said disc comprising:
at least one first type of sector, each at least one first type of sector occupying a first length of a perimeter of said disc and having a distance in a radial direction; and
at least one second type of sector, each at least one second type of sector occupying a second length of the perimeter of said disc and having a distance in the radial direction, wherein the at least one second type of sector is spaced apart from said at least one first type of sector, wherein the second length is different compared to said first length, wherein the distance in the radial direction of the at least one first type of sector and the distance in the radial direction of the at least one second type of sector are different than remaining parts of the disc and wherein said at least one first and second types sectors are irregularly spaced around the perimeter of said disc; and

an inductive sensor arranged to detect said at least one first and second types of sectors and give rise to a binary pulse sequence upon rotation of said disc, and wherein the temporal widths of the binary pulses correspond to the lengths of said at least one first and said at least one second types of sectors, respectively.

11. A disc for a system for detecting the rotation direction of a rotating axis, said disc comprising:
at least one first type of sector, each at least one first type of sector occupying a first length of the perimeter of said disc;
at least one second type of sector, each at least one second type of sector occupying a second length of the perimeter of said disc,
wherein the at least one second type of sector is spaced apart from said at least one first type of sector,
wherein the second length is different compared to said first length,
wherein said at least one first and second types sectors are irregularly spaced around the perimeter of said disc, and
wherein the sectors of the disc have a larger radius compared to the other portions of the disc;
a through hole adapted for the rotating axis; and
an inductive sensor arranged to detect said at least one first and second types of sectors and give rise to a binary pulse sequence upon rotation of said shaft, and wherein the temporal widths of the binary pulses correspond to the lengths of said at least one first and said at least one second types of sectors, respectively.

12. A method for detecting the rotational speed of a centrifugal separator comprising the steps of:
a) providing the centrifugal separator according to claim 1 ;
b) rotating said rotating part of said separator and recording the binary pulse sequence from said sensor;
c) detecting a repetitive pattern in said binary pulse sequence and calculating the time for the disc and rotating part of the separator to rotate a full turn as the time of a cycle in the repetitive pattern; and
d) using the time of a cycle calculated in step c) for calculating the rotational speed of the separator.

13. The method according to claim 12 , wherein the disc of the separator of step a) comprises a single first type of sector and a single second type of sector and step c) comprises calculating the time between every second pulse in the binary pulse sequence.

14. A method for detecting the rotational direction of a rotating part of a centrifugal separator comprising the steps of:
a) providing the centrifugal separator according to claim 1 ;
b) rotating said rotating part of said separator and recording the binary pulse sequence from said sensor; and
c) comparing the pulse sequence from step b) with the shape of the member to conclude the rotational direction of the rotating part of the centrifugal separator.

15. The centrifugal separator according to claim 2 , wherein the member arranged for rotation is a disc arranged around said spindle.

16. The centrifugal separator according to claim 4 , wherein the at least one first type of sector is of the same material as the at least one second type of sector.

17. The centrifugal separator according to claim 5 , wherein the at least one first type of sector is of the same material as the at least one second type of sector.

18. The centrifugal separator according to claim 4 , wherein the disc comprises a single first type of sector and a single second type of sector.

Assignees

• Alfa Laval Corp Ab

Inventors

• Karlsson Per

Classifications

• G01P3/481 Primary

  of pulse signals · CPC title

• G01P3/487 Primary

  delivered by rotating magnets · CPC title

• B04B9/10

  Control of the drive; Speed regulating {(for solid bowl screw centrifuges B04B1/2016)} · CPC title

• G01P13/045

  with speed indication · CPC title

• B04B2005/125

  the rotors comprising separating walls · CPC title