US3687359A

US3687359A - Centrifuge rotor

Info

Publication number: US3687359A
Application number: US104599A
Authority: US
Inventors: Michael J Scanlon
Original assignee: Damon Corp
Current assignee: Damon Corp
Priority date: 1971-01-07
Filing date: 1971-01-07
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29
Also published as: GB1335110A; FR2121624A1; DE2159868A1; FR2121624B1; JPS5632029B1; DE2159868C2

Abstract

A centrifuge rotor having a plurality of chambers each comprising (1) a socket extending through the top surface of the rotor having an inside cylindrical surface terminating in a spherical surface, (2) a slot extending through the peripheral and bottom surfaces of the rotor that is formed by a cylindrical section extending through an arc of 90* with a center along the vertical axis of the socket and below the center of the socket spherical section and (3) a spherical seat connecting the slot and the socket having its center along the horizontal axis of the slot so that the angle between the vertical axis of the rotor and a line between the center of the spherical socket section and the seat is between 55* and 90*. Buckets adapted to fit into the chambers and move between a vertical and horizontal position comprise a top spherical flanged section and a bottom tubular section.

Description

United States Patent Scanlon 1 Aug. 29, 1972 [54] CENTRIFUGE ROTOR [57] ABSTRACT [72] Inventor: Mic -L S 0 .M A centrifuge rotor having a plurality of chambers each 73 A 1 D C N comprising (1) a socket extending through the top sslgnee 2:22: g j t eedham surface of the rotor having an inside cylindrical surface terminating in a spherical surface, (2) a slot exl Flled! J 1971 tending through the peripheral and bottom surfaces of Appl. No.: 104,599

Primary Examiner-Jordan Franklin Assistant ExaminerGeorge H. Krizmanich Att0rneyKenway, Jenney & Hildreth the rotor that is fonncd by a cylindrical section extending through an arc of 90 with a center along the vertical axis of the socket and below the center of the socket spherical section and (3) a spherical seat connecting the slot and the socket having its center along the horizontal axis of the slot so that the angle between the vertical axis of the rotor and a line between the center of the spherical socket section and the seat is between 55 and 90. Buckets adapted to fit into the chambers and move between a vertical and horizontal position comprise a top spherical flanged section and a bottom tubular section.

4 Claims, 3 Drawing Figures Patented Aug. 29, 1972 INVENTOR MICHAEL F. SCANLON TORNEYS CENTRIFUGE ROTOR This invention relates to a centrifuge rotor and to a combination of the centrigue rotor and detachably mounted buckets.

In present centrifuge rotors, buckets are pivotally mounted on the rotors to permit their movement to a horizontal position when the rotor is spinning and back to the vertical position when the rotor is at rest. In one type, the rotor periphery is formed with an outwardly disposed flange having circumferentially spaced vertical slots shaped to accommodate a bucket. The buckets are provided with trunnions having a removable closure that fits into undercut shoulders of the slot to confine them during centrifugation. Proposals for increasing the strength of the pivotal connections have led to increased weight in the rotor which reduces the safe operational rotor speed.

It has been proposed to eliminate this additional construction by providing slots within the rotor shaped to retain buckets while permitting them to pivot between the vertical and horizontal positions. These sockets extend vertically from the bottom surface of the rotor a sufficient distance to permit insertion of the bucket having a spherical shaped flange. A seat, that accommodates the spherical flanged portion of the bucket, extends radially outwardly from the socket to the rotor periphery and is shaped to permit horizontal movement of the bucket. The buckets are placed into the rotor through the bottom surface upwardly into the socket and then outwardly onto the seat. It is difficult for the operator to see whether the bucket has been placed correctly into the seat which results in frequent incorrect placement. When incorrectly placed, the bucket will be jarred into the correct position after rotor startup, rather than moving smoothly between the vertical and horizontal positions, thereby disturbing the sample and gradient, increasing the time needed for the desired separation and disturbing any interface formed during centrifugation. A further undesirable aspect of incorrect placement is the danger that the bucket will be detached from the rotor.

In accordance with the present invention, there is provided a rotor having a socket construction which permits visual observance of bucket loading. The buckets comprises a lower tubular portion and an upper flanged portion having an outer spherical surface with its center coaxial with the vertical axis of the tubular portion. The socket comprises a cylindrical hole extending vertically from the top surface of the rotor and terminating into a spherical surface having the same diameter as the cylinder. The socket is intersected by a slot extending through the peripheral and bottom surfaces of the rotor and is formed by a cylindrical section extending through an arc of 90 with the center of the are being along the vertical axis of the socket and below the center of the socket spherical section. The diameter of the slot is sufficiently large to accommodate the tubular portion of the bucket but smaller than the bucket flange. A spherical seat connecting the slot and the socket has its center along the horizontal axis of the slot, and has the same or slightly smaller diameter as the spherical surface of the socket. The center of the spherical seat is slightly below the center of the spherical section of the socket so that an angle formed by the line between the two centers and the vertical axis of the rotor is between about 55 and about 90; preferably between and The cavities in the rotor are evenly spaced around its circumference so that the rotor is balanced when fully loaded. The buckets are placed in the rotor sockets by inserting the buckets, tubular portion down, through the socket and the slot so that the spherical flange is seated in the spherical section of the sockets. When the rotor is spun, the flanged portion of the bucket slides along the spherical seat allowing the bucket to pivot from the vertical to the horizontal position.

The invention will be more fully described herein with reference to the accompanying drawings.

FIG. 1 is a top plan view, in partial cross section, of a rotor of this invention.

FIG. 2 is a vertical cross-sectional view of the rotor of FIG. 1 taken along line 22.

FIG. 3 is a cross sectional view of a bucket employed in conjunction with the rotor of this invention.

The buckets shown in the figures are generally indicated at 10. Each bucket 10 includes a tubular portion 11 closed at one end and having its other end counter bored to provide a seat 12 for a seal 13 and threaded to receive a cap 14. The bucket 10 is provided with a spherical flange 15 with an outer surface that converges toward the center of the bucket 10. Each tubular portion 11 can be externally tapered to achieve an optimum strength to weight ratio. The taper is slight since the bucket walls are relatively thin and the inside diameter of the tubular portion 11 is constant. However, the use of a tapered bucket is not essential to this invention.

The rotor 16 has central bore 17 to receive a centrifuge spindle, not shown. The bore 17 can be modified in any manner to accommodate a driving means, such as the diametrically disposed channels 17a shown in the figures. The rotor 16 has a plurality of evenly spaced sockets 18 that extend into the rotor 16. The bottom portion of the socket 18 is open to a slot 19 that extends from the peripheral surface 20 of the rotor 16. The diameter of the slot 19 is slightly larger than the outside diameter of the tubular portion 11 of the bucket 10 at the intersection of the flange l5 and the tubular portion 11. Thus, when the rotor is at rest, the tubular portion 11 of the bucket 10 hangs freely through the slot 19 while the spherical flange 15 rests in spherical seat 26. When the rotor 16 is spun, the bucket 10 is pivoted about the spherical flange 15 to the horizontal position as shown in FIG. 2 by the dotted lines.

The socket 18 is formed with a spherical cutting tool to cut a cylindrical hole which terminates in a hemisphere 25. The slot 19 then is formed with a spherical cutting tool which develops a continuous clearance from the bottom surface of the rotor to the periphery of the rotor and intersects the socket. After the slot is formed, a spherical cutting tool of slightly smaller radius than the socket spherical cutting tool is inserted in the socket and moved radially outward and down at a constant angle to form the seat 26.

As shown in FIG. 2, the cylindrical socket 18 has a vertical axis 27 and at the bottom thereof a spherical section 25 which spherical section has a center 28 along the vertical axis 27. A slot 19 extending from the perpherical and bottom surfaces of the rotor 16 comprises a cylindrical section extending through an arc of about which cylindrical section has a center 29 on the vertical axis 27 of socket 18. A spherical seat 26 connects the socket 18 and the slot 19. The spherical seat has a center 30 on the horizontal axis 31 of the slot. The line between

centers

28 and 30 forms an angle, a, between about 55 and 90 with the vertical axis 32 of the rotor 16.

The rotor of the present invention provides substantial advantages in that the buckets can be placed in proper position easily and quickly so that a smooth transition of the bucket is attained when moving between the vertical and horizontal positions when the rotor is driven.

I claim:

1. A rotor having a top surface, a bottom surface and a peripheral surface, a plurality of chambers evenly spaced around the circumference of said top surface and said bottom surface and being equidistant from the vertical axis of said rotor, each of said chambers comprising a. a socket extending through the top surface having an inside cylindrical surface terminating in a spherical section b. a slot extending from said peripheral and bottom surfaces, said slot comprising a cylindrical section extending through an arc of about 90 with a center along the vertical axis of the socket and below the center of the socket spherical section, and

c. a spherical seat connecting the slot and the socket having its center along the horizontal axis of the slot so that the angle between the vertical axis of the rotor and a line between the centers of the spherical section and the seat is between 55 and 90.

said rotor having a top surface, a bottom surface and a peripheral surface, a plurality of chambers evenly spaced around the circumference of said top surface and said bottom surface and being equidistant from the vertical axis of said rotor, each of said chambers comprising a. a socket extending through the top surface having an inside cylindrical surface terminating in a spherical section b. a slot extending from said peripheral and bottom surfaces, said slot comprising a cylindrical section extending through an arc of about 90 with a center along the vertical axis of the socket and below the center of the socket spherical section,

d. buckets having a tubular portion closed at one end and a flange at the other end, said flange having an outside spherical surface that fits into the spherical sections of said socket and said slot and said tubular portion extending through the peripheral and bottom surfaces of said rotor.

3. The rotor of claim 1 wherein the angle between the vertical axis of the rotor and a line between the centers of the spherical section and the seat is between and 4. The rotor of claim 2 wherein the angle between the vertical axis of the rotor and a line between the centers of the spherical section and the seat is between 70 and 75.

Claims

1. A rotor having a top surface, a bottom surface and a peripheral surface, a plurality of chambers evenly spaced around the circumference of said top surface and said bottom surface and being equidistant from the vertical axis of said rotor, each of said chambers comprising a. a socket extending through the top surface having an inside cylindrical surface terminating in a spherical section b. a slot extending from said peripheral and bottom surfaces, said slot comprising a cylindrical section extending through an arc of about 90* with a center along the vertical axis of the socket and below the center of the socket spherical section, and c. a spherical seat connecting the slot and the socket having its center along the horizontal axis of the slot so that the angle between the vertical axis of the rotor and a line between the centers of the spherical section and the seat is between 55* and 90* .

2. In combination, a centrifuge rotor and buckets, said rotor having a top surface, a bottom surface and a peripheral surface, a plurality of chambers evenly spaced around the circumference of said top surface and said bottom surface and being equidistant from the vertical axis of said rotor, each of said chambers comprising a. a socket extending through the top surface having an inside cylindrical surface terminating in a spherical section b. a slot extending from said peripheral and bottom surfaces, said slot comprising a cylindrical section extending through an arc of about 90* with a center along the vertical axis of the socket and below the center of the socket spherical section, c. a spherical seat connecting the slot and the socket having its center along the horizontal axis of the slot so that the angle between the vertical axis of the rotor and a line between the centers of the spherical section and the seat is between 55* and 90* . d. buckets having a tubular portion closed at one end and a flange at the other end, said flange having an outside spherical surface that fits into the spherical sections of said socket and said slot and said tubular portion extending through the peripheral and bottom surfaces of said rotor.

3. The rotor of claim 1 wherein the angle between the vertical axis of the rotor and a line between the centers of the spherical section and the seat is between 70* and 75* .

4. The rotor of claim 2 wherein the angle between the vertical axis of the rotor and a line between the centers of the spherical section and the seat is between 70* and 75* .